Magnetic circular dichroism of CdTe nanoparticles

NASA Astrophysics Data System (ADS)

Malakhovskii, A. V.; Sokolov, A. E.; Tsipotan, A. S.; Zharkov, S. M.; Zabluda, V. N.

2018-04-01

Magnetic circular dichroism (MCD) of water-soluble CdTe nanoparticles was observed in the visible spectral range for the first time. Diameter of nanoparticles varied from 2.3 to 4.5 nm. Absorption and photoluminescence spectra were also recorded. Absorption line at 19400 cm-1 and luminescent line at 18200 cm-1 were observed. Splitting of value 960 cm-1 was revealed in the MCD spectrum. Approximately the same splitting was extracted from the absorption spectrum. The MCD was identified as the temperature independent paramagnetic mixing effect. Nature of the absorption line and of its splitting are discussed.

Detection of delamination defects in CFRP materials using ultrasonic signal processing.

PubMed

Benammar, Abdessalem; Drai, Redouane; Guessoum, Abderrezak

2008-12-01

In this paper, signal processing techniques are tested for their ability to resolve echoes associated with delaminations in carbon fiber-reinforced polymer multi-layered composite materials (CFRP) detected by ultrasonic methods. These methods include split spectrum processing (SSP) and the expectation-maximization (EM) algorithm. A simulation study on defect detection was performed, and results were validated experimentally on CFRP with and without delamination defects taken from aircraft. Comparison of the methods for their ability to resolve echoes are made.

A multiple-scale turbulence model for incompressible flow

NASA Technical Reports Server (NTRS)

Duncan, B. S.; Liou, W. W.; Shih, T. H.

1993-01-01

A multiple-scale eddy viscosity model is described in this paper. This model splits the energy spectrum into a high wave number regime and a low wave number regime. Dividing the energy spectrum into multiple regimes simplistically emulates the cascade of energy through the turbulence spectrum. The constraints on the model coefficients are determined by examining decaying turbulence and homogeneous turbulence. A direct link between the partitioned energies and the energy transfer process is established through the coefficients. This new model has been calibrated and tested for boundary-free turbulent shear flows. Calculations of mean and turbulent properties show good agreement with experimental data for two mixing layers, a plane jet and a round jet.

Three junction holographic micro-scale PV system

NASA Astrophysics Data System (ADS)

Wu, Yuechen; Vorndran, Shelby; Ayala Pelaez, Silvana; Kostuk, Raymond K.

2016-09-01

In this work a spectrum splitting micro-scale concentrating PV system is evaluated to increase the conversion efficiency of flat panel PV systems. In this approach, the dispersed spectrum splitting concentration systems is scaled down to a small size and structured in an array. The spectrum splitting configuration allows the use of separate single bandgap PV cells that increase spectral overlap with the incident solar spectrum. This results in an overall increase in the spectral conversion efficiency of the resulting system. In addition other benefits of the micro-scale PV system are retained such reduced PV cell material requirements, more versatile interconnect configurations, and lower heat rejection requirements that can lead to a lower cost system. The system proposed in this work consists of two cascaded off-axis holograms in combination with a micro lens array, and three types of PV cells. An aspherical lens design is made to minimize the dispersion so that higher concentration ratios can be achieved for a three-junction system. An analysis methodology is also developed to determine the optical efficiency of the resulting system, the characteristics of the dispersed spectrum, and the overall system conversion efficiency for a combination of three types of PV cells.

Outdoor measurements of a photovoltaic system using diffractive spectrum-splitting and concentration

DOE PAGES

Mohammad, N.; Schulz, M.; Wang, P.; ...

2016-09-16

In a single-bandgap absorber, photons having energy less than the bandgap are not absorbed, while those having energy larger than the bandgap lose the excess energy via thermalization. We present outdoor measurements of a photovoltaic system that overcomes these losses via spectrum splitting and concentration using a planar diffractive optic. The system was comprised of the diffractive optic coupled with GaInP and CIGS solar cells. The optic provides a geometric concentration of 3X for each solar cell. It is easily fabricated by single-step grayscale lithography and it is ultra-thin with a maximum thickness of only 2.5μm. Electrical measurements under directmore » sunlight demonstrated an increase of ~25% in total output power compared to the reference case without spectrum splitting and concentration. Since different bandgaps are in the same plane, the proposed photovoltaic system successfully circumvents the lattice-matching and current-matching issues in conventional tandem multi-junction solar cells. As a result, this system is also tolerant to solar spectrum variation and fill-factor degradation of constitutive solar cells.« less

Outdoor measurements of a photovoltaic system using diffractive spectrum-splitting and concentration

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

Mohammad, N.; Schulz, M.; Wang, P.

In a single-bandgap absorber, photons having energy less than the bandgap are not absorbed, while those having energy larger than the bandgap lose the excess energy via thermalization. We present outdoor measurements of a photovoltaic system that overcomes these losses via spectrum splitting and concentration using a planar diffractive optic. The system was comprised of the diffractive optic coupled with GaInP and CIGS solar cells. The optic provides a geometric concentration of 3X for each solar cell. It is easily fabricated by single-step grayscale lithography and it is ultra-thin with a maximum thickness of only 2.5μm. Electrical measurements under directmore » sunlight demonstrated an increase of ~25% in total output power compared to the reference case without spectrum splitting and concentration. Since different bandgaps are in the same plane, the proposed photovoltaic system successfully circumvents the lattice-matching and current-matching issues in conventional tandem multi-junction solar cells. As a result, this system is also tolerant to solar spectrum variation and fill-factor degradation of constitutive solar cells.« less

Strong valley Zeeman effect of dark excitons in monolayer transition metal dichalcogenides in a tilted magnetic field

NASA Astrophysics Data System (ADS)

Van der Donck, M.; Zarenia, M.; Peeters, F. M.

2018-02-01

The dependence of the excitonic photoluminescence (PL) spectrum of monolayer transition metal dichalcogenides (TMDs) on the tilt angle of an applied magnetic field is studied. Starting from a four-band Hamiltonian we construct a theory which quantitatively reproduces the available experimental PL spectra for perpendicular and in-plane magnetic fields. In the presence of a tilted magnetic field, we demonstrate that the dark exciton PL peaks brighten due to the in-plane component of the magnetic field and split for light with different circular polarizations as a consequence of the perpendicular component of the magnetic field. This splitting is more than twice as large as the splitting of the bright exciton peaks in tungsten-based TMDs. We propose an experimental setup that will allow for accessing the predicted splitting of the dark exciton peaks in the PL spectrum.

Ab initio calculations of torsionally mediated hyperfine splittings in E states of acetaldehyde

NASA Astrophysics Data System (ADS)

Xu, Li-Hong; Reid, E. M.; Guislain, B.; Hougen, J. T.; Alekseev, E. A.; Krapivin, I.

2017-12-01

Quantum chemistry packages can be used to predict with reasonable accuracy spin-rotation hyperfine interaction constants for methanol, which contains one methyl-top internal rotor. In this work we use one of these packages to calculate components of the spin-rotation interaction tensor for acetaldehyde. We then use torsion-rotation wavefunctions obtained from a fit to the acetaldehyde torsion-rotation spectrum to calculate the expected magnitude of hyperfine splittings analogous to those observed at relatively high J values in the E symmetry states of methanol. We find that theory does indeed predict doublet splittings at moderate J values in the acetaldehyde torsion-rotation spectrum, which closely resemble those seen in methanol, but that the factor of three decrease in hyperfine spin-rotation constants compared to methanol puts the largest of the acetaldehyde splittings a factor of two below presently available Lamb-dip resolution.

Holographic spectrum-splitting optical systems for solar photovoltaics

NASA Astrophysics Data System (ADS)

Zhang, Deming

Solar energy is the most abundant source of renewable energy available. The relatively high cost prevents solar photovoltaic (PV) from replacing fossil fuel on a larger scale. In solar PV power generation the cost is reduced with more efficient PV technologies. In this dissertation, methods to improve PV conversion efficiency with holographic optical components are discussed. The tandem multiple-junction approach has achieved very high conversion efficiency. However it is impossible to manufacture tandem PV cells at a low cost due to stringent fabrication standards and limited material types that satisfy lattice compatibility. Current produced by the tandem multi-junction PV cell is limited by the lowest junction due to series connection. Spectrum-splitting is a lateral multi-junction concept that is free of lattice and current matching constraints. Each PV cell can be optimized towards full absorption of a spectral band with tailored light-trapping schemes. Holographic optical components are designed to achieve spectrum-splitting PV energy conversion. The incident solar spectrum is separated onto multiple PV cells that are matched to the corresponding spectral band. Holographic spectrum-splitting can take advantage of existing and future low-cost technologies that produces high efficiency thin-film solar cells. Spectrum-splitting optical systems are designed and analyzed with both transmission and reflection holographic optical components. Prototype holograms are fabricated and high optical efficiency is achieved. Light-trapping in PV cells increases the effective optical path-length in the semiconductor material leading to improved absorption and conversion efficiency. It has been shown that the effective optical path length can be increased by a factor of 4n2 using diffusive surfaces. Ultra-light-trapping can be achieved with optical filters that limit the escape angle of the diffused light. Holographic reflection gratings have been shown to act as angle-wavelength selective filters that can function as ultra-light-trapping filters. Results from an experimental reflection hologram are used to model the absorption enhancement factor for a silicon solar cell and light-trapping filter. The result shows a significant improvement in current generation for thin-film silicon solar cells under typical operating conditions.

[Study on the Emission Spectrum of Hydrogen Production with Microwave Discharge Plasma in Ethanol Solution].

PubMed

Sun, Bing; Wang, Bo; Zhu, Xiao-mei; Yan, Zhi-yu; Liu, Yong-jun; Liu, Hui

2016-03-01

Hydrogen is regarded as a kind of clean energy with high caloricity and non-pollution, which has been studied by many experts and scholars home and abroad. Microwave discharge plasma shows light future in the area of hydrogen production from ethanol solution, providing a new way to produce hydrogen. In order to further improve the technology and analyze the mechanism of hydrogen production with microwave discharge in liquid, emission spectrum of hydrogen production by microwave discharge plasma in ethanol solution was being studied. In this paper, plasma was generated on the top of electrode by 2.45 GHz microwave, and the spectral characteristics of hydrogen production from ethanol by microwave discharge in liquid were being studied using emission spectrometer. The results showed that a large number of H, O, OH, CH, C2 and other active particles could be produced in the process of hydrogen production from ethanol by microwave discharge in liquid. The emission spectrum intensity of OH, H, O radicals generated from ethanol is far more than that generated from pure water. Bond of O-H split by more high-energy particles from water molecule was more difficult than that from ethanol molecule, so in the process of hydrogen production by microwave discharge plasma in ethanol solution; the main source of hydrogen was the dehydrogenation and restructuring of ethanol molecules instead of water decomposition. Under the definite external pressure and temperature, the emission spectrum intensity of OH, H, O radicals increased with the increase of microwave power markedly, but the emission spectrum intensity of CH, C2 active particles had the tendency to decrease with the increase of microwave power. It indicated that the number of high energy electrons and active particles high energy electron energy increased as the increase of microwave power, so more CH, C2 active particles were split more thoroughly.

A frequency standard via spectrum analysis and direct digital synthesis

NASA Astrophysics Data System (ADS)

Li, Dawei; Shi, Daiting; Hu, Ermeng; Wang, Yigen; Tian, Lu; Zhao, Jianye; Wang, Zhong

2014-11-01

We demonstrated a frequency standard based on a detuned coherent population beating phenomenon. In this phenomenon, the beat frequency of the radio frequency for laser modulation and the hyperfine splitting can be obtained by digital signal processing technology. After analyzing the spectrum of the beat frequency, the fluctuation information is obtained and applied to compensate for the frequency shift to generate the standard frequency by the digital synthesis method. Frequency instability of 2.6 × 1012 at 1000 s is observed in our preliminary experiment. By eliminating the phase-locking loop, the method will enable us to achieve a full-digital frequency standard with remarkable stability.

Ultra-small v-shaped gold split ring resonators for biosensing using fundamental magnetic resonance in the visible spectrum

NASA Astrophysics Data System (ADS)

Mauluidy Soehartono, Alana; Mueller, Aaron David; Tobing, Landobasa Yosef Mario; Chan, Kok Ken; Zhang, Dao Hua; Yong, Ken-Tye

2017-10-01

Strong light localization within metal nanostructures occurs by collective oscillations of plasmons in the form of electric and magnetic resonances. This so-called localized surface plasmon resonance (LSPR) has gained much interest in the development of low-cost sensing platforms in the visible spectrum. However, demonstrations of LSPR-based sensing are mostly limited to electric resonances due to the technological limitations for achieving magnetic resonances in the visible spectrum. In this work, we report the first demonstration of LSPR sensing based on fundamental magnetic resonance in the visible spectrum using ultrasmall gold v-shaped split ring resonators. Specifically, we show the ability for detecting adsorption of bovine serum albumin and cytochrome c biomolecules at monolayer levels, and the selective binding of protein A/G to immunoglobulin G.

A compact spectrum splitting concentrator for high concentration photovoltaics based on the dispersion of a lens

NASA Astrophysics Data System (ADS)

He, J.; Flowers, C. A.; Yao, Y.; Atwater, H. A.; Rockett, A. A.; Nuzzo, R. G.

2018-06-01

Photovoltaic devices used in conjunction with functional optical elements for light concentration and spectrum splitting are known to be a viable approach for highly efficient photovoltaics. Conventional designs employ discrete optical elements, each with the task of either performing optical concentration or separating the solar spectrum. In the present work, we examine the performance of a compact photovoltaic architecture in which a single lens plays a dual role as both a concentrator and a spectrum splitter, the latter made possible by exploiting its intrinsic dispersion. A four-terminal two-junction InGaP/GaAs device is prepared to validate the concept and illustrates pathways for improvements. A spectral separation in the visible range is demonstrated at the focal point of a plano-convex lens with a geometric concentration ratio of 1104X with respect to the InGaP subcell.

Discriminative and Criterion Validity of the Autism Spectrum Identity Scale (ASIS)

ERIC Educational Resources Information Center

McDonald, T. A. M.

2017-01-01

Individuals on the autism spectrum face stigma that can influence identity development. Previous research on the 22-item Autism Spectrum Identity Scale (ASIS) reported a four-factor structure with strong split-sample cross-validation and good internal consistency. This study reports the discriminative and criterion validity of the ASIS with other…

Active spectroscopic measurements of the bulk deuterium properties in the DIII-D tokamak (invited).

PubMed

Grierson, B A; Burrell, K H; Chrystal, C; Groebner, R J; Kaplan, D H; Heidbrink, W W; Muñoz Burgos, J M; Pablant, N A; Solomon, W M; Van Zeeland, M A

2012-10-01

The neutral-beam induced D(α) emission spectrum contains a wealth of information such as deuterium ion temperature, toroidal rotation, density, beam emission intensity, beam neutral density, and local magnetic field strength magnitude |B| from the Stark-split beam emission spectrum, and fast-ion D(α) emission (FIDA) proportional to the beam-injected fast ion density. A comprehensive spectral fitting routine which accounts for all photoemission processes is employed for the spectral analysis. Interpretation of the measurements to determine physically relevant plasma parameters is assisted by the use of an optimized viewing geometry and forward modeling of the emission spectra using a Monte-Carlo 3D simulation code.

Split-spectrum processing technique for SNR enhancement of ultrasonic guided wave.

PubMed

Pedram, Seyed Kamran; Fateri, Sina; Gan, Lu; Haig, Alex; Thornicroft, Keith

2018-02-01

Ultrasonic guided wave (UGW) systems are broadly used in several branches of industry where the structural integrity is of concern. In those systems, signal interpretation can often be challenging due to the multi-modal and dispersive propagation of UGWs. This results in degradation of the signals in terms of signal-to-noise ratio (SNR) and spatial resolution. This paper employs the split-spectrum processing (SSP) technique in order to enhance the SNR and spatial resolution of UGW signals using the optimized filter bank parameters in real time scenario for pipe inspection. SSP technique has already been developed for other applications such as conventional ultrasonic testing for SNR enhancement. In this work, an investigation is provided to clarify the sensitivity of SSP performance to the filter bank parameter values for UGWs such as processing bandwidth, filter bandwidth, filter separation and a number of filters. As a result, the optimum values are estimated to significantly improve the SNR and spatial resolution of UGWs. The proposed method is synthetically and experimentally compared with conventional approaches employing different SSP recombination algorithms. The Polarity Thresholding (PT) and PT with Minimization (PTM) algorithms were found to be the best recombination algorithms. They substantially improved the SNR up to 36.9dB and 38.9dB respectively. The outcome of the work presented in this paper paves the way to enhance the reliability of UGW inspections. Copyright © 2017 Elsevier B.V. All rights reserved.

Analytical spectrum for a Hamiltonian of quantum dots with Rashba spin-orbit coupling

NASA Astrophysics Data System (ADS)

Dossa, Anselme F.; Avossevou, Gabriel Y. H.

2014-12-01

We determine the analytical solution for a Hamiltonian describing a confined charged particle in a quantum dot, including Rashba spin-orbit coupling and Zeeman splitting terms. The approach followed in this paper is straightforward and uses the symmetrization of the wave function's components. The eigenvalue problem for the Hamiltonian in Bargmann's Hilbert space reduces to a system of coupled first-order differential equations. Then we exploit the symmetry in the system to obtain uncoupled second-order differential equations, which are found to be the Whittaker-Ince limit of the confluent Heun equations. Analytical expressions as well as numerical results are obtained for the spectrum. One of the main features of such models, namely, the level splitting, is present through the spectrum obtained in this paper.

Electron-electron interaction and spin-orbit coupling in InAs/AlSb heterostructures with a two-dimensional electron gas

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

Gavrilenko, V. I.; Krishtopenko, S. S., E-mail: ds_a-teens@mail.ru; Goiran, M.

2011-01-15

The effect of electron-electron interaction on the spectrum of two-dimensional electron states in InAs/AlSb (001) heterostructures with a GaSb cap layer with one filled size-quantization subband. The energy spectrum of two-dimensional electrons is calculated in the Hartree and Hartree-Fock approximations. It is shown that the exchange interaction decreasing the electron energy in subbands increases the energy gap between subbands and the spin-orbit splitting of the spectrum in the entire region of electron concentrations, at which only the lower size-quantization band is filled. The nonlinear dependence of the Rashba splitting constant at the Fermi wave vector on the concentration of two-dimensionalmore » electrons is demonstrated.« less

Harmonic Composition of the Currents of Power Windings in 500 KV Thyristor Controlled Shunt Reactor with Split Valveside Windings

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

Matinyan, A. M., E-mail: al-drm@mail.ru; Peshkov, M. V.; Karpov, V. N.

2016-09-15

The design and current spectrum of a thyristor valve controlled shunt reactor (TCSR) with split valveside windings are described. The dependence of the amplitudes of higher-order harmonics of the power winding current on the TCSR operating regime are presented for this TCSR design.

A robust power spectrum split cancellation-based spectrum sensing method for cognitive radio systems

NASA Astrophysics Data System (ADS)

Qi, Pei-Han; Li, Zan; Si, Jiang-Bo; Gao, Rui

2014-12-01

Spectrum sensing is an essential component to realize the cognitive radio, and the requirement for real-time spectrum sensing in the case of lacking prior information, fading channel, and noise uncertainty, indeed poses a major challenge to the classical spectrum sensing algorithms. Based on the stochastic properties of scalar transformation of power spectral density (PSD), a novel spectrum sensing algorithm, referred to as the power spectral density split cancellation method (PSC), is proposed in this paper. The PSC makes use of a scalar value as a test statistic, which is the ratio of each subband power to the full band power. Besides, by exploiting the asymptotic normality and independence of Fourier transform, the distribution of the ratio and the mathematical expressions for the probabilities of false alarm and detection in different channel models are derived. Further, the exact closed-form expression of decision threshold is calculated in accordance with Neyman—Pearson criterion. Analytical and simulation results show that the PSC is invulnerable to noise uncertainty, and can achive excellent detection performance without prior knowledge in additive white Gaussian noise and flat slow fading channels. In addition, the PSC benefits from a low computational cost, which can be completed in microseconds.

Many-body and spin-orbit aspects of the alternating current phenomena

NASA Astrophysics Data System (ADS)

Glenn, Rachel M.

The thesis reports on research in the general field of light interaction with matter. According to the topics addressed, it can be naturally divided into two parts: Part I, many-body aspects of the Rabi oscillations which a two-level systems undergoes under a strong resonant drive; and Part II, absorption of the ac field between the spectrum branches of two-dimensional fermions that are split by the combined action of Zeeman and spin-orbit (SO) fields. The focus of Part I is the following many-body effects that modify the conventional Rabi oscillations: Chapter 1, coupling of a two-level system to a single vibrational mode of the environment. Chapter 2, correlated Rabi oscillations in two electron-hole systems coupled by tunneling with strong electron-hole attraction. In Chapter 1, a new effect of Rabi-vibronic resonance is uncovered. If the frequency of the Rabi oscillations, OR, is close to the frequency o0 of the vibrational mode, the oscillations acquire a collective character. It is demonstrated that the actual frequency of the collective oscillations exhibits a bistable behavior as a function of OR - o0. The main finding in Chapter 2 is, that the Fourier spectrum of the Rabi oscillations in two coupled electron-hole systems undergoes a strong transformation with increasing O R. For OR smaller than the tunneling frequency, the spectrum is dominated by a low-frequency (<< OR ) component and contains two additional weaker lines; conventional Rabi oscillations are restored only as OR exceeds the electron-hole attraction strength. The highlight of Part II is a finding that, while the spectrum of absorption between either Zeeman-split branches or SO-split branches is close to a delta-peak, in the presence of both, it transforms into a broad line with singular behavior at the edges. In particular, when the magnitudes of Zeeman and SO are equal, absorption of very low (much smaller than the splitting) frequencies become possible. The shape of the absorption spectrum is highly anisotropic with respect to the exciting field. This peculiar behavior of the absorption is also studied in wire geometry, where the interplay between two couplings (Zeeman and spin-orbit splitting) affects the shape of numerous absorption peaks.

Flux vector splitting of the inviscid equations with application to finite difference methods

NASA Technical Reports Server (NTRS)

Steger, J. L.; Warming, R. F.

1979-01-01

The conservation-law form of the inviscid gasdynamic equations has the remarkable property that the nonlinear flux vectors are homogeneous functions of degree one. This property readily permits the splitting of flux vectors into subvectors by similarity transformations so that each subvector has associated with it a specified eigenvalue spectrum. As a consequence of flux vector splitting, new explicit and implicit dissipative finite-difference schemes are developed for first-order hyperbolic systems of equations. Appropriate one-sided spatial differences for each split flux vector are used throughout the computational field even if the flow is locally subsonic. The results of some preliminary numerical computations are included.

Efficient tungsten oxide/bismuth oxyiodide core/shell photoanode for photoelectrochemical water splitting

NASA Astrophysics Data System (ADS)

Ma, Haipeng; Zhang, Jing; Liu, Zhifeng

2017-11-01

The novel WO3 nanorods (NRs)/BiOI core/shell structure composite is used as an efficient photoanode applied in photoelectrochemical (PEC) water splitting for the first time. It is synthesized via facile hydrothermal method and, successive ionic layer adsorption and reaction (SILAR) process. This facile synthesis route can achieve uniform WO3/BiOI core/shell composite nanostructures and obtain varied BiOI morphologies simultaneously. The WO3 NRs/BiOI-20 composite exhibits enhanced PEC activity compared to pristine WO3 with a photocurrent density of 0.79 mA cm-2 measured at 0.8 V vs. RHE under AM 1.5G. This excellent performance benefits from the broader absorption spectrum and suppressed electron-hole recombination. This novel core/shell composite may provide insight in developing more efficient solar driven photoelectrodes.

Surface Plasmon Enhanced Sensitive Detection for Possible Signature of Majorana Fermions via a Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

PubMed Central

Chen, Hua-Jun; Zhu, Ka-Di

2015-01-01

In the present work, we theoretically propose an optical scheme to detect the possible signature of Majorana fermions via the optical pump-probe spectroscopy, which is very different from the current tunneling measurement based on electrical methods. The scheme consists of a metal nanoparticle and a semiconductor quantum dot coupled to a hybrid semiconductor/superconductor heterostructures. The results show that the probe absorption spectrum of the quantum dot presents a distinct splitting due to the existence of Majorana fermions. Owing to surface plasmon enhanced effect, this splitting will be more obvious, which makes Majorana fermions more easy to be detectable. The technique proposed here open the door for new applications ranging from robust manipulation of Majorana fermions to quantum information processing based on Majorana fermions. PMID:26310929

Spectrum splitting using multi-layer dielectric meta-surfaces for efficient solar energy harvesting

NASA Astrophysics Data System (ADS)

Yao, Yuhan; Liu, He; Wu, Wei

2014-06-01

We designed a high-efficiency dispersive mirror based on multi-layer dielectric meta-surfaces. By replacing the secondary mirror of a dome solar concentrator with this dispersive mirror, the solar concentrator can be converted into a spectrum-splitting photovoltaic system with higher energy harvesting efficiency and potentially lower cost. The meta-surfaces are consisted of high-index contrast gratings (HCG). The structures and parameters of the dispersive mirror (i.e. stacked HCG) are optimized based on finite-difference time-domain and rigorous coupled-wave analysis method. Our numerical study shows that the dispersive mirror can direct light with different wavelengths into different angles in the entire solar spectrum, maintaining very low energy loss. Our approach will not only improve the energy harvesting efficiency, but also lower the cost by using single junction cells instead of multi-layer tandem solar cells. Moreover, this approach has the minimal disruption to the existing solar concentrator infrastructures.

Graphene-based terahertz metasurface with tunable spectrum splitting.

PubMed

Su, Zhaoxian; Chen, Xuan; Yin, Jianbo; Zhao, Xiaopeng

2016-08-15

We design a tunable terahertz metasurface, which consists of two different trapezoid graphene ribbons patterned in opposite directions on a gold film, separated by a thin dielectric spacer. The two kinds of graphene ribbons can cover a nearly 2π phase shift with high reflection efficiency in different spectral regions so that the metasurface can reflect different frequency waves to totally different directions. By changing the Fermi level of the graphene ribbons, the response frequency of the proposed metasurface can be adjusted, and as a result, tunable spectrum splitting can be realized. The present metasurface provides a powerful way to control terahertz waves and has potential applications in wide-angle beam splitters.

Objectively discriminating the optical analogy of electromagnetically induced transparency from Autler-Townes splitting in a side coupled graphene-based waveguide system

NASA Astrophysics Data System (ADS)

Wei, Buzheng; Jian, Shuisheng

2017-11-01

A mid-infrared side coupled graphene nanotube waveguide system is proposed to investigate the origin discerning from electromagnetically induced transparency (EIT) to Autler-Townes splitting (ATS). The analytic transmission analysis seeks an evolution tendency of transmission spectrum from ATS to EIT, which is numerically verified by the simulation results. The origin of transparency is mainly attributed to ATS effect in the strong coupling regime while EIT is favored in the weak coupling condition. We plot the field distribution to help understand the underlying physics of the interference process. The high group index of 5000 indicates that a slow light effect is successfully observed and Fano resonance is presented by varying the Fermi energy of the dark mode. These ideas may provide potential views in filters, optical buffers, light storage and on chip metamaterials.

Environmental stability study of holographic solar spectrum splitting materials

NASA Astrophysics Data System (ADS)

Chrysler, Benjamin D.; Ayala Pelaez, Silvana; Wu, Yuechen; Vorndran, Shelby D.; Kostuk, Raymond K.

2016-09-01

In this study the impact of outdoor temperature variations and solar illumination exposure on spectral filter material and holographic optical elements is examined. Although holographic components have been shown to be useful for solar spectrum splitting designs, relatively little quantitative data exist to demonstrate the extent to which these materials can withstand outdoor conditions. As researchers seek to investigate practical spectrum splitting designs, the environmental stability of holographic materials should be considered as an important factor. In the experiment presented, two holographic materials, Covestro Bayfol HX photopolymer and dichromated gelatin, and 3M reflective polymer filter materials are exposed to outdoor conditions for a period of several months. The environmental effect on absorption, spectral and angular bandwidth, peak efficiency, and Bragg matching conditions for the holograms are examined. Spectral bandwidth and transmittance of the 3M reflective filter material are also monitored. Holographic gratings are recorded, measured, and mounted on glass substrates and then sealed with a glass cover plate. The test samples are then mounted on a photovoltaic panel to simulate realistic temperature conditions and placed at an outdoor test facility in Tucson, Arizona. A duplicate set of holograms and 3M filter material is stored as a control group and periodically compared over the test period.

Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

PubMed

Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

2016-09-20

This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm.

New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting.

PubMed

Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

2016-09-01

Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed.

Time-dependent wave splitting and source separation

NASA Astrophysics Data System (ADS)

Grote, Marcus J.; Kray, Marie; Nataf, Frédéric; Assous, Franck

2017-02-01

Starting from classical absorbing boundary conditions, we propose a method for the separation of time-dependent scattered wave fields due to multiple sources or obstacles. In contrast to previous techniques, our method is local in space and time, deterministic, and avoids a priori assumptions on the frequency spectrum of the signal. Numerical examples in two space dimensions illustrate the usefulness of wave splitting for time-dependent scattering problems.

Enhancing photovoltaic output power by 3-band spectrum-splitting and concentration using a diffractive micro-optic

DOE PAGES

Mohammad, Nabil; Wang, Peng; Friedman, Daniel J.; ...

2014-09-17

We report the enhancement of photovoltaic output power by separating the incident spectrum into 3 bands, and concentrating these bands onto 3 different photovoltaic cells. The spectrum-splitting and concentration is achieved via a thin, planar micro-optical element that demonstrates high optical efficiency over the entire spectrum of interest. The optic (which we call a polychromat) was designed using a modified version of the direct-binary-search algorithm. The polychromat was fabricated using grayscale lithography. Rigorous optical characterization demonstrates excellent agreement with simulation results. Electrical characterization of the solar cells made from GaInP, GaAs and Si indicate increase in the peak output powermore » density of 43.63%, 30.84% and 30.86%, respectively when compared to normal operation without the polychromat. This represents an overall increase of 35.52% in output power density. As a result, the potential for cost-effective large-area manufacturing and for high system efficiencies makes our approach a strong candidate for low cost solar power.« less

Energy production advantage of independent subcell connection for multijunction photovoltaics

DOE PAGES

Warmann, Emily C.; Atwater, Harry A.

2016-07-07

Increasing the number of subcells in a multijunction or "spectrum splitting" photovoltaic improves efficiency under the standard AM1.5D design spectrum, but it can lower efficiency under spectra that differ from the standard if the subcells are connected electrically in series. Using atmospheric data and the SMARTS multiple scattering and absorption model, we simulated sunny day spectra over 1 year for five locations in the United States and determined the annual energy production of spectrum splitting ensembles with 2-20 subcells connected electrically in series or independently. While electrically independent subcells have a small efficiency advantage over series-connected ensembles under the AM1.5Dmore » design spectrum, they have a pronounced energy production advantage under realistic spectra over 1 year. Simulated energy production increased with subcell number for the electrically independent ensembles, but it peaked at 8-10 subcells for those connected in series. As a result, electrically independent ensembles with 20 subcells produce up to 27% more energy annually than the series-connected 20-subcell ensemble. This energy production advantage persists when clouds are accounted for.« less

Energy production advantage of independent subcell connection for multijunction photovoltaics

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

Warmann, Emily C.; Atwater, Harry A.

Increasing the number of subcells in a multijunction or "spectrum splitting" photovoltaic improves efficiency under the standard AM1.5D design spectrum, but it can lower efficiency under spectra that differ from the standard if the subcells are connected electrically in series. Using atmospheric data and the SMARTS multiple scattering and absorption model, we simulated sunny day spectra over 1 year for five locations in the United States and determined the annual energy production of spectrum splitting ensembles with 2-20 subcells connected electrically in series or independently. While electrically independent subcells have a small efficiency advantage over series-connected ensembles under the AM1.5Dmore » design spectrum, they have a pronounced energy production advantage under realistic spectra over 1 year. Simulated energy production increased with subcell number for the electrically independent ensembles, but it peaked at 8-10 subcells for those connected in series. As a result, electrically independent ensembles with 20 subcells produce up to 27% more energy annually than the series-connected 20-subcell ensemble. This energy production advantage persists when clouds are accounted for.« less

Using a biased qubit to probe complex systems

NASA Astrophysics Data System (ADS)

Pollock, Felix A.; Checińska, Agata; Pascazio, Saverio; Modi, Kavan

2016-09-01

Complex mesoscopic systems play increasingly important roles in modern science, from understanding biological functions at the molecular level to designing solid-state information processing devices. The operation of these systems typically depends on their energetic structure, yet probing their energy landscape can be extremely challenging; they have many degrees of freedom, which may be hard to isolate and measure independently. Here, we show that a qubit (a two-level quantum system) with a biased energy splitting can directly probe the spectral properties of a complex system, without knowledge of how they couple. Our work is based on the completely positive and trace-preserving map formalism, which treats any unknown dynamics as a "black-box" process. This black box contains information about the system with which the probe interacts, which we access by measuring the survival probability of the initial state of the probe as function of the energy splitting and the process time. Fourier transforming the results yields the energy spectrum of the complex system. Without making assumptions about the strength or form of its coupling, our probe could determine aspects of a complex molecule's energy landscape as well as, in many cases, test for coherent superposition of its energy eigenstates.

Processing of transparent polycrystalline AlON:Ce 3+ scintillators

DOE PAGES

Chen, Ching -Fong; Yang, Pin; King, Graham; ...

2015-10-23

A new polycrystalline ceramic scintillator is reported for potential use in radiation detection and medical imaging applications. The goal was to develop cerium-activated aluminum oxynitride (AlON:Ce 3+) ceramics, which can be produced using ceramic processes in comparison to the high-cost, low-yield single-crystal growth technique. A phase pure AlON:Ce 3+ powder with cubic symmetry was successfully synthesized at high temperature under a reducing atmosphere to convert Ce 4+ to Ce 3+ in the solid solution. We explored two different activator concentrations (0.5 and 1.0 mol%). Fully dense and transparent AlON:Ce 3+ ceramics were produced by a liquid-phase-assisted pressureless sintering. The crystalmore » field splitting around the Ce 3+ activator in the AlON was comparable to the splitting induced by Br₋ and the Cl₋ ligands, which produced an emission spectrum perfectly matching the maximum quantum efficiency range of the photomultiplier tube for radiation detection. Both optical excitation and radiation ionizations in AlON:Ce 3+ were demonstrated. Lastly, challenges and mechanisms related to the radioluminescence efficiency are discussed.« less

Dual-energy imaging using a photon counting detector with electronic spectrum-splitting

NASA Astrophysics Data System (ADS)

Bornefalk, Hans; Lundqvist, Mats

2006-03-01

This paper presents a dual-energy imaging technique optimized for contrast-enhanced mammography using a photon counting detector. Each photon pulse is processed separately in the detector and the addition of an electronic threshold near the middle of the energy range of the x-ray spectrum allows discrimination of high and low energy photons. This effectively makes the detector energy sensitive, and allows the acquisition of high- and low-energy images simultaneously. These high- and low-energy images can be combined to dual-energy images where the anatomical clutter has been suppressed. By setting the electronic threshold close to 33.2 keV (the k-edge of iodine) the system is optimized for dual-energy contrast-enhanced imaging of breast tumors. Compared to other approaches, this method not only eliminates the need for separate exposures that might lead to motion artifacts, it also eliminates the otherwise deteriorating overlap between high- and low-energy spectra. We present phantom dual-energy images acquired on a prototype system to illustrate that the technique is already operational, albeit in its infancy. We also present a theoretical estimation of the potential gain in tumor signal-difference-to-noise ratio when using this electronic spectrum-splitting method as opposed to acquiring the high- and low-energy images separately with double exposures with separate x-ray spectra. Assuming ideal energy sensitive photon counting detectors, we arrive at the conclusion that the signal-difference-to-noise ratio could be increased by 145% at constant dose. We also illustrate our results on synthetic images.

Quasi-particle spectrum in trilayer graphene: Role of onsite coulomb interaction and interlayer coupling

NASA Astrophysics Data System (ADS)

Kumar, Sanjay; Ajay

2015-01-01

Stacking dependent quasi-particle spectrum and density of states (DOS) in trilayer (ABC-, ABA- and AAA-stacked) graphene are analyzed using mean-field Green's function equations of motion method. Interlayer coupling (t1) is found to be responsible for the splitting of quasi-particle peaks in each stacking order. Coulomb interaction suppresses the trilayer splitting and generates a finite gap at Fermi level in ABC- while a tiny gap in ABA-stacked trilayer graphene. Influence of t⊥ is prominent for AAA-stacking as compared to ABC- and ABA-stacking orders. The theoretically obtained quasi-particle energies and DOS has been viewed in terms of recent angle resolved photoemission spectroscopic (ARPES) and scanning tunneling microscopic (STM) data available on these systems.

Improved Coal-Thickness Measurement

NASA Technical Reports Server (NTRS)

Barr, T. A.

1984-01-01

Summed signals and dielectric-filled antenna improve measurement. Improved FM radar for measuring thickness of coal seam eliminates spectrum splitting and reduces magnitude of echo from front coal surface.

What is and what is not electromagnetically induced transparency in whispering-gallery microcavities.

PubMed

Peng, Bo; Özdemir, Sahin Kaya; Chen, Weijian; Nori, Franco; Yang, Lan

2014-10-24

There has been an increasing interest in all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting. Despite the differences in their underlying physics, both electromagnetically induced transparency and Autler-Townes splitting are quantified by a transparency window in the absorption or transmission spectrum, which often leads to a confusion about its origin. While the transparency window in electromagnetically induced transparency is a result of Fano interference among different transition pathways, in Autler-Townes splitting it is the result of strong field-driven interactions leading to the splitting of energy levels. Being able to tell objectively whether an observed transparency window is because of electromagnetically induced transparency or Autler-Townes splitting is crucial for applications and for clarifying the physics involved. Here we demonstrate the pathways leading to electromagnetically induced transparency, Fano resonances and Autler-Townes splitting in coupled whispering-gallery-mode resonators. Moreover, we report the application of the Akaike Information Criterion discerning between all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting and clarifying the transition between them.

[Research on improving spectrum resolution of optimized Wollaston prism array].

PubMed

Zhang, Peng; Wang, Jian-Rong; Zhang, Guo-Chen; Hou, Wen

2011-11-01

In order to not affect the image quality of interference fringes on the basis of the structure by increasing the structure angle of Wollaston prism to improve spectrum resolution, the authors optimized the structure of Wollaston prism. Calculating the function of the splitting angle and the structure angle, analysis indicated that taking the isosceles triangle prism with the same nature of the second wedge-shaped prism after the Wollaston prism, which makes the o and e light parallel to the optical axis, and alpha=0 degrees, the imaging interference fringes are no longer affected by changes in the splitting angle. Several optimized Wollaston prisms were made as an array to improve the spectral resolution. Experiments used traditional and optimized Wollaston prism array to detect the spectrum of the 980 nm laser. Experimental data showed that using optimized Wollaston prism array gets a clearer contrast of interference fringes, and the spectral data with Fourier transform are more accurate with DSP.

AGILE OBSERVATIONS OF THE 'SOFT' GAMMA-RAY PULSAR PSR B1509 - 58

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

Pilia, M.; Pellizzoni, A.; Esposito, P.

2010-11-01

We present the results of new AGILE observations of PSR B1509 - 58 performed over a period of {approx}2.5 years following the detection obtained with a subset of the present data. The modulation significance of the light curve above 30 MeV is at a 5{sigma} confidence level and the light curve is similar to those found earlier by COMPTEL up to 30 MeV: a broad asymmetric first peak reaching its maximum 0.39 {+-} 0.02 cycles after the radio peak plus a second peak at 0.94 {+-} 0.03. The gamma-ray spectral energy distribution of the pulsed flux detected by COMPTEL andmore » AGILE is well described by a power law (photon index {alpha} = 1.87 {+-} 0.09) with a remarkable cutoff at E{sub c} = 81 {+-} 20 MeV, representing the softest spectrum observed among gamma-ray pulsars so far. The pulsar luminosity at E > 1 MeV is L{sub {gamma}} = 4.2{sup +0.5}{sub -0.2} x 10{sup 35} erg s{sup -1}, assuming a distance of 5.2 kpc, which implies a spin-down conversion efficiency to gamma rays of {approx}0.03. The unusual soft break in the spectrum of PSR B1509 - 58 has been interpreted in the framework of polar cap models as a signature of the exotic photon-splitting process in the strong magnetic field of this pulsar. In this interpretation, our spectrum constrains the magnetic altitude of the emission point(s) at 3 km above the neutron star surface, implying that the attenuation may not be as strong as formerly suggested because pair production can substitute photon splitting into regions of the magnetosphere where the magnetic field becomes too low to sustain photon splitting. In the case of an outer-gap scenario or the two-pole caustic model, better constraints on the geometry of the emission would be needed from the radio band in order to establish whether the conditions required by the models to reproduce AGILE light curves and spectra match the polarization measurements.« less

High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system

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

Uzu, Hisashi, E-mail: Hisashi.Uzu@kaneka.co.jp, E-mail: npark@skku.edu; Ichikawa, Mitsuru; Hino, Masashi

2015-01-05

We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an “optical splitter.” An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cellmore » or a CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells.« less

Landau level splitting due to graphene superlattices

NASA Astrophysics Data System (ADS)

Pal, G.; Apel, W.; Schweitzer, L.

2012-06-01

The Landau level spectrum of graphene superlattices is studied using a tight-binding approach. We consider noninteracting particles moving on a hexagonal lattice with an additional one-dimensional superlattice made up of periodic square potential barriers, which are oriented along the zigzag or along the armchair directions of graphene. In the presence of a perpendicular magnetic field, such systems can be described by a set of one-dimensional tight-binding equations, the Harper equations. The qualitative behavior of the energy spectrum with respect to the strength of the superlattice potential depends on the relation between the superlattice period and the magnetic length. When the potential barriers are oriented along the armchair direction of graphene, we find for strong magnetic fields that the zeroth Landau level of graphene splits into two well-separated sublevels, if the width of the barriers is smaller than the magnetic length. In this situation, which persists even in the presence of disorder, a plateau with zero Hall conductivity can be observed around the Dirac point. This Landau level splitting is a true lattice effect that cannot be obtained from the generally used continuum Dirac-fermion model.

Reliability of the Matson Evaluation of Social Skills with Youngsters (MESSY) for Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Matson, Johnny L.; Horovitz, Max; Mahan, Sara; Fodstad, Jill

2013-01-01

The purpose of this paper was to update the psychometrics of the "Matson Evaluation of Social Skills for Youngsters" ("MESSY") with children with Autism Spectrum Disorders (ASD), specifically with respect to internal consistency, split-half reliability, and inter-rater reliability. In Study 1, 114 children with ASD (Autistic Disorder, Asperger's…

Broadband Gerchberg-Saxton algorithm for freeform diffractive spectral filter design.

PubMed

Vorndran, Shelby; Russo, Juan M; Wu, Yuechen; Pelaez, Silvana Ayala; Kostuk, Raymond K

2015-11-30

A multi-wavelength expansion of the Gerchberg-Saxton (GS) algorithm is developed to design and optimize a surface relief Diffractive Optical Element (DOE). The DOE simultaneously diffracts distinct wavelength bands into separate target regions. A description of the algorithm is provided, and parameters that affect filter performance are examined. Performance is based on the spectral power collected within specified regions on a receiver plane. The modified GS algorithm is used to design spectrum splitting optics for CdSe and Si photovoltaic (PV) cells. The DOE has average optical efficiency of 87.5% over the spectral bands of interest (400-710 nm and 710-1100 nm). Simulated PV conversion efficiency is 37.7%, which is 29.3% higher than the efficiency of the better performing PV cell without spectrum splitting optics.

Visible near-infrared light scattering of single silver split-ring structure made by nanosphere lithography.

PubMed

Okamoto, Toshihiro; Fukuta, Tetsuya; Sato, Shuji; Haraguchi, Masanobu; Fukui, Masuo

2011-04-11

We succeeded in making a silver split-ring (SR) structure of approximately 130 nm in diameter on a glass substrate using a nanosphere lithography technique. The light scattering spectrum in visible near-infrared region of a single, isolated SR was measured using a microscope spectroscopy optical system. The electromagnetic field enhancement spectrum and distribution of the SR structure were simulated by the finite-difference time-domain method, and the excitation modes were clarified. The long wavelength peak in the light scattering spectra corresponded to a fundamental LC resonance mode excited by an incident electric field. It was shown that a single SR structure fabricated as abovementioned can operate as a resonator and generate a magnetic dipole. © 2011 Optical Society of America

Shock Mitigation in Open-Celled TiNi Foams

NASA Astrophysics Data System (ADS)

Jardine, A. Peter

2018-05-01

High-energy shock events generated by impacts are effectively mitigated by Nitinol materials. Initial evidence of this capability was suggested by the dramatically superior cavitation-erosion performance of Nitinol coatings made by plasma spray processes, over steels and brasses. A fast acting hysteretic stress-strain response mechanism was proposed to explain this result, transforming the shock energy into heat. Extending this work to bulk TiNi, dynamic load characterization using Split Rod Hopkinson Bar techniques on solid porous TiNi confirmed that the mechanical response to high strain rates below 4200 s-1 were indeed hysteretic. This paper reports on dynamical load characterization on TiNi foams made by Self-Propagating High-Temperature Synthesis (SHS) using Split Rod Hopkinson Bar and gas-gun impact characterization to compare these foams to alternative materials. This work verified that SHS-derived TiNi foams were indeed hysteretic at strain rates from 180 to 2300 s-1. In addition, Shock Spectrum Analysis demonstrated that TiNi foams were very effective in mitigating the shock spectrum range below 5 kHz, and that increasing porosity increased the amount of shock attenuation in that spectral range. Finally under impact loading, 55% porous TiNi foams were a factor of 7 superior to steel and a factor of 4 better than Al 6061 or Cu in mitigating peak g-loads and this attenuation improved with bilayer structures of 57 and 73% porous TiNi foam article.

Preparation of cauliflower-like CdS/ZnS/ZnO nanostructure and its photoelectric properties

NASA Astrophysics Data System (ADS)

Liu, Zhifeng; Guo, Keying; Wang, Yun; Zheng, Xuerong; Ya, Jing; Li, Junwei; Han, Li; Liu, Zhichao; Han, Jianhua

2014-06-01

Cauliflower-like CdS/ZnS/ZnO nanostructure is fabricated via a simple hydrothermal method. Factors such as concentration of reaction solution, reaction temperature, as well as reaction time in the synthetic process are investigated, and the working mechanism of the nanostructure is suggested. Hydrogen generation efficiency of 4.69 % at 0.29 V versus saturated calomel electrode is achieved using synthesized nanostructure as electrode due to the improved absorption and appropriate energy gap structure, which is confirmed by enhanced absorption spectrum. The expected products have potential application in photoelectrochemical water splitting.

Evaluating Sensory Processing in Fragile X Syndrome: Psychometric Analysis of the Brain Body Center Sensory Scales (BBCSS).

PubMed

Kolacz, Jacek; Raspa, Melissa; Heilman, Keri J; Porges, Stephen W

2018-06-01

Individuals with fragile X syndrome (FXS), especially those co-diagnosed with autism spectrum disorder (ASD), face many sensory processing challenges. However, sensory processing measures informed by neurophysiology are lacking. This paper describes the development and psychometric properties of a parent/caregiver report, the Brain-Body Center Sensory Scales (BBCSS), based on Polyvagal Theory. Parents/guardians reported on 333 individuals with FXS, 41% with ASD features. Factor structure using a split-sample exploratory-confirmatory design conformed to neurophysiological predictions. Internal consistency, test-retest, and inter-rater reliability were good to excellent. BBCSS subscales converged with the Sensory Profile and Sensory Experiences Questionnaire. However, data also suggest that BBCSS subscales reflect unique features related to sensory processing. Individuals with FXS and ASD features displayed more sensory challenges on most subscales.

The rotational spectrum of the water-hydroperoxy radical (H2O-HO2) complex.

PubMed

Suma, Kohsuke; Sumiyoshi, Yoshihiro; Endo, Yasuki

2006-03-03

Peroxy radicals and their derivatives are elusive but important intermediates in a wide range of oxidation processes. We observed pure rotational transitions of the water-hydroperoxy radical complex, H2O-HO2, in a supersonic jet by means of a Fourier transform microwave spectrometer combined with a double-resonance technique. The observed rotational transitions were found to split into two components because of the internal rotation of the water moiety. The molecular constants for the two components were determined precisely, supporting a molecular structure in which HO2 acts as a proton donor to form a nearly planar five-membered ring, and one hydrogen atom of water sticks out from the ring plane. The structure and the spectral splittings due to internal rotation provide information on the nature of the bonding interaction between open- and closed-shell species, and they also provide accurate transition frequencies that are applicable to remote sensing of this complex, which may elucidate its potential roles in atmospheric and combustion chemistry.

Mg I absorption features in the solar spectrum near 9 and 12 microns

NASA Technical Reports Server (NTRS)

Glenar, David A.; Reuter, Dennis C.; Deming, Drake; Chang, Edward S.

1988-01-01

High-resolution FTS observations from the Kitt Peak National Solar Observatory and the Spacelab 3 ATMOS experiment have revealed additional infrared transitions due to Mg I in the spectra of both quiet sun and sunspot penumbra. In contrast to previous observations, these transitions are seen in absorption, not emission. Absorption intensities range from 1 to 7 percent of the continuum in the quiet sun. In the penumbra, the same features appear to show Zeeman splitting. Modeling of the line profiles in the photospheric spectrum shows evidence for a factor of three overabundance in the n = 5 or more levels of Mg I in the upper photosphere, but with no deviations from a Planck source function. It is concluded that whatever the process that produces the emission (including the Lemke and Holweger mechanism), it must occur well above the tau(5000) = 0.01 level.

Neutrino mass hierarchy and three-flavor spectral splits of supernova neutrinos

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

Dasgupta, Basudeb; Mirizzi, Alessandro; Tomas, Ricard

2010-05-01

It was recently realized that three-flavor effects could peculiarly modify the development of spectral splits induced by collective oscillations, for supernova neutrinos emitted during the cooling phase of a protoneutron star. We systematically explore this case, explaining how the impact of these three-flavor effects depends on the ordering of the neutrino masses. In inverted mass hierarchy, the solar mass splitting gives rise to instabilities in regions of the (anti)neutrino energy spectra that were otherwise stable under the leading two-flavor evolution governed by the atmospheric mass splitting and by the 1-3 mixing angle. As a consequence, the high-energy spectral splits foundmore » in the electron (anti)neutrino spectra disappear, and are transferred to other flavors. Imperfect adiabaticity leads to smearing of spectral swap features. In normal mass hierarchy, the three-flavor and the two-flavor instabilities act in the same region of the neutrino energy spectrum, leading to only minor departures from the two-flavor treatment.« less

Prediction of the bottomonium D-wave spectrum from full lattice QCD.

PubMed

Daldrop, J O; Davies, C T H; Dowdall, R J

2012-03-09

We calculate the full spectrum of D-wave states in the Υ system in lattice QCD for the first time, by using an improved version of nonrelativistic QCD on coarse and fine "second-generation" gluon field configurations from the MILC Collaboration that include the effect of up, down, strange, and charm quarks in the sea. By taking the 2S-1S splitting to set the lattice spacing, we determine the (3)D2-1S splitting to 2.3% and find agreement with experiment. Our prediction of the fine structure relative to the (3)D2 gives the (3)D3 at 10.181(5) GeV and the (3)D1 at 10.147(6) GeV. We also discuss the overlap of (3)D1 operators with (3)S1 states.

The EPR study of Mn(2+) ion doped DADT single crystal produced under high pressure and temperature.

PubMed

Ceylan, Ümit; Tapramaz, Recep

2016-01-05

An EPR study on Cu(2+) and VO(2+) doped di ammonium d-tartrate single crystals has been reported in previous papers, but the same host did not accept Mn(2+) ion at the same reaction conditions in previous trials. In this study EPR study of Mn(2+) ion doped di ammonium d tartrate single crystal, (DADT) [(NH4)2C4H4O6], produced in a reactor under high pressure and high temperature. The electronic transitions were determined by the optical absorption spectrum. Hyperfine splitting and g values of the Mn(2+) ion forming a complex in the lattice were measured from experimental spectra and spin-spin dipolar splitting parameters D and E were found by the spectrum simulation techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

Brief Report: IQ Split Predicts Social Symptoms and Communication Abilities in High-Functioning Children with Autism Spectrum Disorders

PubMed Central

Wallace, Gregory L.; Sokoloff, Jennifer L.; Kenworthy, Lauren

2011-01-01

We investigated the relationship of discrepancies between VIQ and NVIQ (IQ split) to autism symptoms and adaptive behavior in a sample of high-functioning (mean FSIQ = 98.5) school-age children with autism spectrum disorders divided into three groups: discrepantly high VIQ (n = 18); discrepantly high NVIQ (n = 24); and equivalent VIQ and NVIQ (n = 36). Discrepantly high VIQ and NVIQ were associated with autism social symptoms but not communication symptoms or repetitive behaviors. Higher VIQ and NVIQ were associated with better adaptive communication but not socialization or Daily Living Skills. IQ discrepancy may be an important phenotypic marker in autism. Although better verbal abilities are associated with better functional outcomes in autism, discrepantly high VIQ in high-functioning children may also be associated with social difficulties. PMID:19572193

Laser induced fluorescence of BaS: Sm phosphor and energy level splitting of Sm 3+ ion

NASA Astrophysics Data System (ADS)

Thomas, Reethamma; Nampoori, V. P. N.

1990-03-01

Fluorescence of BaS: Sm phosphor has been studied using a pulsed Nitrogen laser (337.1 nm) as the excitation source. The spectrum consists of a broad band in the region 540-660nm superposed by the characteristic Sm 3+ lines. Energy level splitting pattern of Sm 3+ due to crystal field effects has been calculated and relevent field parameters are evaluated. Analysis shows that Sm 3+ takes up Ba 2+ substitutional sites.

International Conference on Quantum Chemical Calculations of NMR and EPR Parameters Held in Castle Smolenice, Slovak Republic on September 14-18 1998

DTIC Science & Technology

1998-10-21

site. The electric-field- induced linear shift is also observed in the hyperfine splitting of nuclear quadrupole resonance ( NQR ) spectrum of a nucleus...located at a noncentrosymmetric site in a molecule or in crystal lattice. Thus, the linear electric field effect on the ESR and NQR hyperfine splitting...the electric field effects on ESR and NQR hyperfine couplings. Theoretical methods to calculate the electric field effects within Hartree-Fock

Fine-structure-resolution for Rovibrational Excitation of CN Due to H2

NASA Astrophysics Data System (ADS)

Byrd, Nat; Yang, Benhui H.; Stancil, Phillip C.

2018-06-01

Diatomic molecules can be readily excited in interstellar environments exposed to intense UV radiation, such as the inner rim of a protoplanetary disk. Non-thermal populations of excited rovibrational levels can result, for example, following decay from electronically excited states to the electronic ground state. Competition between radiative decay and collisional processes, mostly due to H2, determine the resulting rovibrational emission spectrum. For CN, and other open-shell molecules, the resulting spectrum will be complicated due to fine-structure splitting of the rotational levels. In some cases, fine-structure resolution has been previously computed for rotational transitions in atom- or diatom-diatom collisional processes. Here we present the first fine-structure resolution for vibrational deexcitation for CN colliding with H2. The collisional cross sections were computed using a 6D potential energy surface with a full close-coupling approach. Fine-structure resolution is obtained by adopting an angular momentum recoupling scheme to transform the scattering matrices to a recoupled basis. Here we present low-energy calculations for the v=1 to 0 transition.This work was supported by NASA Grant NNX16AF09G.

Missing Links Between Genetically Inherited Molecules in Split Cord Malformation and Other Anomaly: A Bench to Bedside Approach

PubMed Central

Barik, Mayadhar; Mishra, Pravash R.; Mohapatra, Ashok Kumar

2018-01-01

Aim: Split cord malformation (SCM) is associated with extensive vertebral fusions (Klippel–Feil anomaly). In light of previous embryological theories and recent research findings, we attempt to document the origin of split cord, and vertebral fusions involvement of spectrum of genes is necessary to know better the etiopathogenesis of SCM and its associated diseases. Materials and Methods: We used the various databases such as PubMed/MEDLINE, Cochrane Review, Hinari, and Google Scholar for the recently published medical literature. The women had been living and still born infants had SCM. The relative risk (RR) and possible molecular mechanism are described details of major genes and its variants in details. Although molecular genetics involvement including with recent advances of study add an evidence of both Mendelian and Non-Mendelian fashion is discussed with all genetic components. We mentioned our earlier experience and responsibility of SCM and its associated diseases. Results: Although different mechanisms are suggested for the development of SCM observed in our experience, there is a midline lesion bisecting the neuroepithelium and the notochordal plate, which is responsible for complete splitting of the cervical cord with anterior bony defect. The localized disturbance of cervical neural tube closure accounts for SCM with partial dorsal splitting of the cord with posterior vertebral defect and associated diseases. Conclusions: According to the best of our knowledge, this report is the first one to be documented by wider spectrum of variants from (experimental studies to human subject). This add a complex interaction of mutant variants drive toward an additional second-hit alterations for the SCM. The up-to-date information, documented in proper order, derived the bench-to-bedside approach to overcome this burden of SCM, which is globally noticed with other additional diseases. PMID:29899771

Missing Links Between Genetically Inherited Molecules in Split Cord Malformation and Other Anomaly: A Bench to Bedside Approach.

PubMed

Barik, Mayadhar; Mishra, Pravash R; Mohapatra, Ashok Kumar

2018-01-01

Split cord malformation (SCM) is associated with extensive vertebral fusions (Klippel-Feil anomaly). In light of previous embryological theories and recent research findings, we attempt to document the origin of split cord, and vertebral fusions involvement of spectrum of genes is necessary to know better the etiopathogenesis of SCM and its associated diseases. We used the various databases such as PubMed/MEDLINE, Cochrane Review, Hinari, and Google Scholar for the recently published medical literature. The women had been living and still born infants had SCM. The relative risk (RR) and possible molecular mechanism are described details of major genes and its variants in details. Although molecular genetics involvement including with recent advances of study add an evidence of both Mendelian and Non-Mendelian fashion is discussed with all genetic components. We mentioned our earlier experience and responsibility of SCM and its associated diseases. Although different mechanisms are suggested for the development of SCM observed in our experience, there is a midline lesion bisecting the neuroepithelium and the notochordal plate, which is responsible for complete splitting of the cervical cord with anterior bony defect. The localized disturbance of cervical neural tube closure accounts for SCM with partial dorsal splitting of the cord with posterior vertebral defect and associated diseases. According to the best of our knowledge, this report is the first one to be documented by wider spectrum of variants from (experimental studies to human subject). This add a complex interaction of mutant variants drive toward an additional second-hit alterations for the SCM. The up-to-date information, documented in proper order, derived the bench-to-bedside approach to overcome this burden of SCM, which is globally noticed with other additional diseases.

Theoretical analysis of polarization-coupled mode splitting in a single microfiber knot-ring resonator

NASA Astrophysics Data System (ADS)

Qiu, Weiqia; Zhou, Junjie; Yu, Jianhui; Xiao, Yi; Lu, Huihui; Guan, Heyuan; Zhong, Yongchun; Zhang, Jun; Chen, Zhe

2016-06-01

We established a theoretical model for a single knot-ring resonator and investigated the transmission spectrum by Jones matrix. The numerical results show that two orthogonal polarization modes of knot-ring, which are originally resonated at the same wavelength, will split into two resonant modes with different wavelengths. The mode splitting is due to the coupling between the two orthogonal polarization modes in the knot-ring when the twisted angle of the twist coupler is not exactly equal to 2mπ (m is an integer). It is also found that the separation of the mode splitting is linearly proportional to the deviation angle δθ with a high correlation coefficient of 99.6% and a slope of 3.17 nm/rad. Furthermore, a transparency phenomenon analogous to coupled-resonator-induced transparency was also predicted by the model. These findings may have potential applications in lasers and sensors.

A quantum mechanical approach to establishing the magnetic field orientation from a maser Zeeman profile

NASA Astrophysics Data System (ADS)

Green, J. A.; Gray, M. D.; Robishaw, T.; Caswell, J. L.; McClure-Griffiths, N. M.

2014-06-01

Recent comparisons of magnetic field directions derived from maser Zeeman splitting with those derived from continuum source rotation measures have prompted new analysis of the propagation of the Zeeman split components, and the inferred field orientation. In order to do this, we first review differing electric field polarization conventions used in past studies. With these clearly and consistently defined, we then show that for a given Zeeman splitting spectrum, the magnetic field direction is fully determined and predictable on theoretical grounds: when a magnetic field is oriented away from the observer, the left-hand circular polarization is observed at higher frequency and the right-hand polarization at lower frequency. This is consistent with classical Lorentzian derivations. The consequent interpretation of recent measurements then raises the possibility of a reversal between the large-scale field (traced by rotation measures) and the small-scale field (traced by maser Zeeman splitting).

The ground state infrared spectrum of the MnH radical ( 7Σ) from diode laser spectroscopy

NASA Astrophysics Data System (ADS)

Urban, Rolf-Dieter; Jones, Harold

1989-11-01

The infrared spectrum of the manganese hydride radical ( 55MnH) in its ground electronic state ( 7Σ) has been observed using a diode laser spectrometer. The wavenumbers of twelve transitions of the v=1→0 band, five of the v=2→1 band and seven of the v=3→2 band have been measured with a nominal accuracy of ±0.001 cm -1. Coupling between the electronic spin ( S=3) and the overall molecular rotation causes each ro-vibrational transition with N>3 to be split (γ splitting) into seven components each separated by a few hundredths of a wavenumber. In most cases the complete structure was resolved. Correction terms arising from spin-spin coupling had to be included in the analysis. This work has produced the most accurate set of ground-state parameters available for MnH.

Multi-Channel Capacitive Sensor Arrays

PubMed Central

Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

2016-01-01

In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

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

Head, J.; Turner, J.A.

2006-01-01

Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable ofmore » splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 to 4.0 eV. Corrosion measurements reveal that the silicon nitride samples exhibit both p-type and n-type behavior. Photocurrent over a range of potentials was greater in samples that were submerged in acidic electrolyte. Silicon nitride shows good stability in acidic, neutral, and basic solutions, indicative of a good material for corrosion mitigation.« less

Hyperpolarized 131Xe NMR spectroscopy

PubMed Central

Stupic, Karl F.; Cleveland, Zackary I.; Pavlovskaya, Galina E.; Meersmann, Thomas

2011-01-01

Hyperpolarized (hp) 131Xe with up to 2.2% spin polarization (i.e., 5000-fold signal enhancement at 9.4 T) was obtained after separation from the rubidium vapor of the spin-exchange optical pumping (SEOP) process. The SEOP was applied for several minutes in a stopped-flow mode, and the fast, quadrupolar-driven T1 relaxation of this spin I = 3/2 noble gas isotope required a rapid subsequent rubidium removal and swift transfer into the high magnetic field region for NMR detection. Because of the xenon density dependent 131Xe quadrupolar relaxation in the gas phase, the SEOP polarization build-up exhibits an even more pronounced dependence on xenon partial pressure than that observed in 129Xe SEOP. 131Xe is the only stable noble gas isotope with a positive gyromagnetic ratio and shows therefore a different relative phase between hp signal and thermal signal compared to all other noble gases. The gas phase 131Xe NMR spectrum displays a surface and magnetic field dependent quadrupolar splitting that was found to have additional gas pressure and gas composition dependence. The splitting was reduced by the presence of water vapor that presumably influences xenon-surface interactions. The hp 131Xe spectrum shows differential line broadening, suggesting the presence of strong adsorption sites. Beyond hp 131Xe NMR spectroscopy studies, a general equation for the high temperature, thermal spin polarization, P, for spin I⩾1/2 nuclei is presented. PMID:21051249

A multiple-time-scale turbulence model based on variable partitioning of turbulent kinetic energy spectrum

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Chen, C.-P.

1988-01-01

The paper presents a multiple-time-scale turbulence model of a single point closure and a simplified split-spectrum method. Consideration is given to a class of turbulent boundary layer flows and of separated and/or swirling elliptic turbulent flows. For the separated and/or swirling turbulent flows, the present turbulence model yielded significantly improved computational results over those obtained with the standard k-epsilon turbulence model.

Weak coupling limit of F-theory models with MSSM spectrum and massless U(1)'s

NASA Astrophysics Data System (ADS)

Mayorga Peña, Damián Kaloni; Valandro, Roberto

2018-03-01

We consider the Sen limit of several global F-theory compactifications, some of which exhibit an MSSM-like spectrum. We show that these indeed have a consistent limit where they can be viewed as resulting from an intersecting brane configuration in type IIB. We discuss the match of the fluxes and the chiral spectrum in detail. We find that some D5-tadpole canceling gauge fluxes do not lift to harmonic vertical four-form fluxes in the resolved F-theory manifold. We discuss the connection between splitting of curves at weak coupling and remnant discrete symmetries.

Physics of the infrared spectrum

NASA Technical Reports Server (NTRS)

Deming, Drake; Jennings, Donald E.; Jefferies, John; Lindsey, Charles

1991-01-01

The IR bandpass is attractive for solar magnetic field studies in virtue of the proportionality to wavelength of the ratio of Zeeman splitting to line width. The large Zeeman splitting and optical thinness of the 12-micron observations render them especially useful for vector magnetic field derivations. The IR continuum, and many IR spectral lines, are formed in LTE and are useful in studies of the temperature structure of the solar atmosphere from the deepest observable photospheric layers to chromospheric altitudes. The far-IR continuum is an excellent thermometer for the upper photosphere and chromosphere.

Systematic Bandgap Engineering of Graphene Quantum Dots and Applications for Photocatalytic Water Splitting and CO2 Reduction.

PubMed

Yan, Yibo; Chen, Jie; Li, Nan; Tian, Jingqi; Li, Kaixin; Jiang, Jizhou; Liu, Jiyang; Tian, Qinghua; Chen, Peng

2018-04-24

Graphene quantum dots (GQDs), which is the latest addition to the nanocarbon material family, promise a wide spectrum of applications. Herein, we demonstrate two different functionalization strategies to systematically tailor the bandgap structures of GQDs whereby making them snugly suitable for particular applications. Furthermore, the functionalized GQDs with a narrow bandgap and intramolecular Z-scheme structure are employed as the efficient photocatalysts for water splitting and carbon dioxide reduction under visible light. The underlying mechanisms of our observations are studied and discussed.

Emergence of a spectral gap in a class of random matrices associated with split graphs

NASA Astrophysics Data System (ADS)

Bassler, Kevin E.; Zia, R. K. P.

2018-01-01

Motivated by the intriguing behavior displayed in a dynamic network that models a population of extreme introverts and extroverts (XIE), we consider the spectral properties of ensembles of random split graph adjacency matrices. We discover that, in general, a gap emerges in the bulk spectrum between -1 and 0 that contains a single eigenvalue. An analytic expression for the bulk distribution is derived and verified with numerical analysis. We also examine their relation to chiral ensembles, which are associated with bipartite graphs.

The Far Infrared Vibration-Rotation Spectrum of the Ammonia Dimer.

NASA Astrophysics Data System (ADS)

Loeser, Jennifer Gertrud

1995-11-01

The ammonia dimer has been shown to exhibit unusual weak bonding properties relative to those of the other prototypical second row systems, the hydrogen fluoride dimer and the water dimer. The ultimate goal of the work initiated in this dissertation is to determine a complete intermolecular potential energy surface for the ammonia dimer. It is first necessary to observe its far infrared vibration-rotation-tunneling (VRT) spectrum and to develop a group theoretical model that explains this spectrum in terms of the internal dynamics of the ammonia dimer. These first steps are the subject of this dissertation. First, the current understanding of the ammonia dimer system is reviewed. Group theoretical descriptions of the nature of the ammonia dimer VRT states are explained in detail. An overview of the experimental and theoretical studies of the ammonia dimer made during the last decade is presented. Second, progress on the analysis of the microwave and far infrared spectrum of (ND_3)_2 below 13 cm^{-1} is reported. These spectra directly measure the 'donor -acceptor' interchange splittings in (ND_3) _2, and determine some of the monomer umbrella inversion tunneling splittings. Third, new 80-90 cm^{-1} far infrared spectra of (NH_3)_2 are presented and a preliminary analysis is proposed. Most of the new excited VRT states have been assigned as tunneling sublevels of an out-of-plane intermolecular vibration.

High performance, high bandgap, lattice-mismatched, GaInP solar cells

DOEpatents

Wanlass, Mark W; Carapella, Jeffrey J; Steiner, Myles A

2016-11-01

High performance, high bandgap, lattice-mismatched, photovoltaic cells (10), both transparent and non-transparent to sub-bandgap light, are provided as devices for use alone or in combination with other cells in split spectrum apparatus or other applications.

High performance, high bandgap, lattice-mismatched, GaInP solar cells

DOEpatents

Wanlass, Mark W.; Carapella, Jeffrey J.; Steiner, Myles A.

2014-07-08

High performance, high bandgap, lattice-mismatched, photovoltaic cells (10), both transparent and non-transparent to sub-bandgap light, are provided as devices for use alone or in combination with other cells in split spectrum apparatus or other applications.

Spectra of Lorentz-violating Dirac bound states in a cylindrical well

NASA Astrophysics Data System (ADS)

Xiao, Zhi

2016-12-01

In the presence of the Lorentz-violating bμ coefficient, the spectra of bound states for a Dirac particle in a cylindric well are changed. Compared to the Lorentz invariant (LI) spectrum, the Lorentz violation deviation becomes significant when eigenenergy E is sufficiently close to the critical values ±m , where m is the particle's mass. The detailed profile of the deviation depends on the observer Lorentz nature of bμ. We discussed three types of bμ configuration. When bμ=(0 ,0 ,0 ,bZ) is parallel to the well axis, the would be degenerate LI spectra split into two subspectra, reminiscent of the Zeeman splitting in the presence of a weak magnetic field. Depending on the relative sign of bZ accompanying mass m in the dispersion relation, the spectrum extends or shrinks in the allowed eigenenergy region. When bμ is a radial [bμ=(0 ,b cos ϕ ,b sin ϕ ,0 ) ] or purely timelike vector [bμ=(bT,0 →)], the spin-up and down components are coupled together, and there is no splitting. However, the monotonic increasing behavior of well depth V0 with the decrease of eigenenergy E is slightly changed when E is sufficiently close to -m .

Temporal self-splitting of optical pulses

NASA Astrophysics Data System (ADS)

Ding, Chaoliang; Koivurova, Matias; Turunen, Jari; Pan, Liuzhan

2018-05-01

We present mathematical models for temporally and spectrally partially coherent pulse trains with Laguerre-Gaussian and Hermite-Gaussian Schell-model statistics as extensions of the standard Gaussian Schell model for pulse trains. We derive propagation formulas of both classes of pulsed fields in linearly dispersive media and in temporal optical systems. It is found that, in general, both types of fields exhibit time-domain self-splitting upon propagation. The Laguerre-Gaussian model leads to multiply peaked pulses, while the Hermite-Gaussian model leads to doubly peaked pulses, in the temporal far field (in dispersive media) or at the Fourier plane of a temporal system. In both model fields the character of the self-splitting phenomenon depends both on the degree of temporal and spectral coherence and on the power spectrum of the field.

Vacuum-induced Autler-Townes splitting in a superconducting artificial atom

NASA Astrophysics Data System (ADS)

Peng, Z. H.; Ding, J. H.; Zhou, Y.; Ying, L. L.; Wang, Z.; Zhou, L.; Kuang, L. M.; Liu, Yu-xi; Astafiev, O. V.; Tsai, J. S.

2018-06-01

We experimentally study a vacuum-induced Autler-Townes doublet in a superconducting three-level artificial atom strongly coupled to a coplanar waveguide resonator and simultaneously to a transmission line. The Autler-Townes splitting is observed in the reflection spectrum from the three-level atom in a transition between the ground state and the second excited state when the transition between the two excited states is resonant with a resonator. By applying a driving field to the resonator, we observe a change in the regime of the Autler-Townes splitting from quantum (vacuum-induced) to classical (with many resonator photons). Furthermore, we show that the reflection of propagating microwaves in a transmission line could be controlled by different frequency microwave fields at the single-photon level in a resonator.

Vibration-Rotation Spectrum of Formic Acid Dimer in the 7.3μm Region

NASA Astrophysics Data System (ADS)

Duan, Chuanxi

2016-06-01

The vibration-rotation-tunneling spectrum of formic acid dimer, (HCOOH)2, in the spectral region 1369-1375 wn has been measured by a multi-step rapid-can method in a slit jet expansion using a distributed-feedback quantum cascade laser. The observed spectrum is assigned to the O-C-H bending fundamental band. The tunneling splitting in the vibrational excited state is determined to be about 0.005 wn, which is much smaller than that in the ground state, 0.0165 wn (Goroya et al.,J. Chem. Phys. 140, 164311 (2014)). Strong local perturbations involving transitions with J > 9, K = 0 and 1 are identified in the observed spectrum. The deperturbation analysis will be presented.

Rotational Spectrum of 1,1-Difluoroethane: Internal Rotation Analysis and Structure

NASA Astrophysics Data System (ADS)

Villamanan, R. M.; Chen, W. D.; Wlodarczak, G.; Demaison, J.; Lesarri, A. G.; Lopez, J. C.; Alonso, J. L.

1995-05-01

The rotational spectrum of CH3CHF2 in its ground state was measured up to 653 GHz. Accurate rotational and centrifugal distortion constants were determined. The internal rotation splittings were analyzed using the internal axis method. An ab initio structure has been calculated and a near-equilibrium structure has been estimated using offsets derived empirically. This structure was compared to an experimental r0 structure. The four lowest excited states (including the methyl torsion) have also been assigned.

Pointwise regularity of parameterized affine zipper fractal curves

NASA Astrophysics Data System (ADS)

Bárány, Balázs; Kiss, Gergely; Kolossváry, István

2018-05-01

We study the pointwise regularity of zipper fractal curves generated by affine mappings. Under the assumption of dominated splitting of index-1, we calculate the Hausdorff dimension of the level sets of the pointwise Hölder exponent for a subinterval of the spectrum. We give an equivalent characterization for the existence of regular pointwise Hölder exponent for Lebesgue almost every point. In this case, we extend the multifractal analysis to the full spectrum. In particular, we apply our results for de Rham’s curve.

PARTIAL REVISION: ABSORPTION SPECTRUM AND QUANTUM STATES OF THE PRASEODYMIUM ION. I. SINGLE CRYSTALS OF PRASEODYMIUM CHLORIDE

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

Sayre, E.V.; Sancier, K.M.; Freed, S.

1958-07-01

In an analysis of term splitting in the absorption spectrum of 24 samples of praseodymium chloride, Judd (Proc. Roy. Soc. (London) A241, 414(1957)) found all but two of the authors' results to be constant with his. A discussion of reconciliation is presentrd, and the authors point out that the error is due to a mistake in descrimination between electronic transitions and the weak vibrationally coupled lines. (J.R.D.)

Spectroscopy of triply charmed baryons from lattice QCD

DOE PAGES

Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; ...

2014-10-14

The spectrum of excitations of triply-charmed baryons is computed using lattice QCD including dynamical light quark fields. The spectrum obtained has baryonic states with well-defined total spin up to 7/2 and the low-lying states closely resemble the expectation from models with an SU(6) x O(3) symmetry. As a result, energy splittings between extracted states, including those due to spin-orbit coupling in the heavy quark limit are computed and compared against data at other quark masses.

Scattering theory of efficient quantum transport across finite networks

NASA Astrophysics Data System (ADS)

Walschaers, Mattia; Mulet, Roberto; Buchleitner, Andreas

2017-11-01

We present a scattering theory for the efficient transmission of an excitation across a finite network with designed disorder. We show that the presence of randomly positioned network sites allows significant acceleration of the excitation transfer processes as compared to a dimer structure, but only if the disordered Hamiltonians are constrained to be centrosymmetric and exhibit a dominant doublet in their spectrum. We identify the cause of this efficiency enhancement to be the constructive interplay between disorder-induced fluctuations of the dominant doublet’s splitting and the coupling strength between the input and output sites to the scattering channels. We find that the characteristic strength of these fluctuations together with the channel coupling fully control the transfer efficiency.

QX MAN: Q and X file manipulation

NASA Technical Reports Server (NTRS)

Krein, Mark A.

1992-01-01

QX MAN is a grid and solution file manipulation program written primarily for the PARC code and the GRIDGEN family of grid generation codes. QX MAN combines many of the features frequently encountered in grid generation, grid refinement, the setting-up of initial conditions, and post processing. QX MAN allows the user to manipulate single block and multi-block grids (and their accompanying solution files) by splitting, concatenating, rotating, translating, re-scaling, and stripping or adding points. In addition, QX MAN can be used to generate an initial solution file for the PARC code. The code was written to provide several formats for input and output in order for it to be useful in a broad spectrum of applications.

DETECTION OF FLUX EMERGENCE, SPLITTING, MERGING, AND CANCELLATION OF NETWORK FIELD. I. SPLITTING AND MERGING

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

Iida, Y.; Yokoyama, T.; Hagenaar, H. J.

2012-06-20

Frequencies of magnetic patch processes on the supergranule boundary, namely, flux emergence, splitting, merging, and cancellation, are investigated through automatic detection. We use a set of line-of-sight magnetograms taken by the Solar Optical Telescope (SOT) on board the Hinode satellite. We found 1636 positive patches and 1637 negative patches in the data set, whose time duration is 3.5 hr and field of view is 112'' Multiplication-Sign 112''. The total numbers of magnetic processes are as follows: 493 positive and 482 negative splittings, 536 positive and 535 negative mergings, 86 cancellations, and 3 emergences. The total numbers of emergence and cancellationmore » are significantly smaller than those of splitting and merging. Further, the frequency dependence of the merging and splitting processes on the flux content are investigated. Merging has a weak dependence on the flux content with a power-law index of only 0.28. The timescale for splitting is found to be independent of the parent flux content before splitting, which corresponds to {approx}33 minutes. It is also found that patches split into any flux contents with the same probability. This splitting has a power-law distribution of the flux content with an index of -2 as a time-independent solution. These results support that the frequency distribution of the flux content in the analyzed flux range is rapidly maintained by merging and splitting, namely, surface processes. We suggest a model for frequency distributions of cancellation and emergence based on this idea.« less

Psychometric Properties of the Autism-Spectrum Quotient for Assessing Low and High Levels of Autistic Traits in College Students.

PubMed

Stevenson, Jennifer L; Hart, Kari R

2017-06-01

The current study systematically investigated the effects of scoring and categorization methods on the psychometric properties of the Autism-Spectrum Quotient. Four hundred and three college students completed the Autism-Spectrum Quotient at least once. Total scores on the Autism-Spectrum Quotient had acceptable internal consistency and test-retest reliability using a binary or Likert scoring method, but the results were more varied for the subscales. Overall, Likert scoring yielded higher internal consistency and test-retest reliability than binary scoring. However, agreement in categorization of low and high autistic traits was poor over time (except for a median split on Likert scores). The results support using Likert scoring and administering the Autism-Spectrum Quotient at the same time as the task of interest with neurotypical participants.

Transition from an optical precursor in coupled-resonator-induced transparency to coherent energy exchange in Autler-Townes splitting

NASA Astrophysics Data System (ADS)

Oishi, Tohru; Suzuki, Ryuta; Talukder, Aminul I.; Tomita, Makoto

2013-08-01

We investigated the transient responses of coupled optical resonators, after they were injected with square modulated temporal pulses. A sharp spike, attributed to the optical precursor in coupled-resonator-induced transparency, appeared when the coupling between the resonators was weak. As the coupling strength increased, the resonance spectrum developed clearly separated double dips of Autler-Townes splitting, and the precursor spike transformed into an oscillatory structure. These temporal oscillations were attributed to the coherent energy exchange between two resonators. Theoretical calculations were in good agreement with the experimental observations.

Giant Rashba splitting in 2D organic-inorganic halide perovskites measured by transient spectroscopies

DOE PAGES

Zhai, Yaxin; Baniya, Sangita; Zhang, Chuang; ...

2017-07-28

Two-dimensional (2D) layered hybrid organic-inorganic halide perovskite semiconductors form natural “multiple quantum wells” that have strong spin-orbit coupling due to the heavy elements in their building blocks. This may lead to “Rashba splitting” close to the extrema in the electron bands. We have used a plethora of ultrafast transient, nonlinear optical spectroscopies and theoretical calculations to study the primary (excitons) and long-lived (free carriers) photoexcitations in thin films of 2D perovskite, namely, (C 6H 5C 2H 4NH 3) 2PbI 4. The density functional theory calculation shows the occurrence of Rashba splitting in the plane perpendicular to the 2D barrier. Frommore » the electroabsorption spectrum and photoinduced absorption spectra from excitons and free carriers, we obtain a giant Rashba splitting in this compound, with energy splitting of (40 ± 5) meV and Rashba parameter of (1.6 ± 0.1) eV·Å, which are among the highest Rashba splitting size parameters reported so far. In conclusion, this finding shows that 2D hybrid perovskites have great promise for potential applications in spintronics.« less

Spectral split in a prompt supernova neutrino burst: Analytic three-flavor treatment

NASA Astrophysics Data System (ADS)

Dasgupta, Basudeb; Dighe, Amol; Mirizzi, Alessandro; Raffelt, Georg G.

2008-06-01

The prompt νe burst from a core-collapse supernova is subject to both matter-induced flavor conversions and strong neutrino-neutrino refractive effects. For the lowest-mass progenitors, leading to O-Ne-Mg core supernovae, the matter density profile can be so steep that the usual Mikheyev-Smirnov-Wolfenstein matter effects occur within the dense-neutrino region close to the neutrino sphere. In this case a “split” occurs in the emerging spectrum, i.e., the νe flavor survival probability shows a steplike feature. We explain this feature analytically as a spectral split prepared by the Mikheyev-Smirnov-Wolfenstein effect. In a three-flavor treatment, the steplike feature actually consists of two narrowly spaced splits. They are determined by two combinations of flavor-lepton numbers that are conserved under collective oscillations.

Opportunistic Capacity-Based Resource Allocation for Chunk-Based Multi-Carrier Cognitive Radio Sensor Networks

PubMed Central

Huang, Jie; Zeng, Xiaoping; Jian, Xin; Tan, Xiaoheng; Zhang, Qi

2017-01-01

The spectrum allocation for cognitive radio sensor networks (CRSNs) has received considerable research attention under the assumption that the spectrum environment is static. However, in practice, the spectrum environment varies over time due to primary user/secondary user (PU/SU) activity and mobility, resulting in time-varied spectrum resources. This paper studies resource allocation for chunk-based multi-carrier CRSNs with time-varied spectrum resources. We present a novel opportunistic capacity model through a continuous time semi-Markov chain (CTSMC) to describe the time-varied spectrum resources of chunks and, based on this, a joint power and chunk allocation model by considering the opportunistically available capacity of chunks is proposed. To reduce the computational complexity, we split this model into two sub-problems and solve them via the Lagrangian dual method. Simulation results illustrate that the proposed opportunistic capacity-based resource allocation algorithm can achieve better performance compared with traditional algorithms when the spectrum environment is time-varied. PMID:28106803

Resonance hybridization and near field properties of strongly coupled plasmonic ring dimer-rod nanosystem

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

Koya, Alemayehu Nana; Ji, Boyu; Hao, Zuoqiang

2015-09-21

Combined effects of polarization, split gap, and rod width on the resonance hybridization and near field properties of strongly coupled gold dimer-rod nanosystem are comparatively investigated in the light of the constituent nanostructures. By aligning polarization of the incident light parallel to the long axis of the nanorod, introducing small split gaps to the dimer walls, and varying width of the nanorod, we have simultaneously achieved resonance mode coupling, huge near field enhancement, and prolonged plasmon lifetime. As a result of strong coupling between the nanostructures and due to an intense confinement of near fields at the split and dimer-rodmore » gaps, the extinction spectrum of the coupled nanosystem shows an increase in intensity and blueshift in wavelength. Consequently, the near field lifespan of the split-nanosystem is prolonged in contrast to the constituent nanostructures and unsplit-nanosystem. On the other hand, for polarization of the light perpendicular to the long axis of the nanorod, the effect of split gap on the optical responses of the coupled nanosystem is found to be insignificant compared to the parallel polarization. These findings and such geometries suggest that coupling an array of metallic split-ring dimer with long nanorod can resolve the huge radiative loss problem of plasmonic waveguide. In addition, the Fano-like resonances and immense near field enhancements at the split and dimer-rod gaps imply the potentials of the nanosystem for practical applications in localized surface plasmon resonance spectroscopy and sensing.« less

Discovery of novel solid solution Ca3Si3-x O3+x N4-2x : Eu2+ phosphors: structural evolution and photoluminescence tuning.

PubMed

Wang, Baochen; Liu, Yan-Gai; Huang, Zhaohui; Fang, Minghao; Wu, Xiaowen

2017-12-22

Discovery of novel phosphors is one of the main issues for improving the color rendering index (CRI) and correlated color temperature (CCT) of white light-emitting diodes (w-LEDs). This study mainly presents a systematic research on the synthesis, crystal structure variation and photoluminescence tuning of novel (oxy)nitride solid solution Ca 3 Si 3-x O 3+x N 4-2x : Eu 2+ phosphors. XRD refinements show that lattice distortion occurs when x value diverges the optimum one (x = 1). The lattice distortion causes a widening of emission spectrum and an increase of Stokes shift (ΔSS), which leads to a bigger thermal quenching. With decrease of x value, the emission spectrum shows an obvious red-shift from 505.2 to 540.8 nm, which is attributed to the crystal field splitting. The enhanced crystal field splitting also broadens the excitation spectrum, making it possible to serve as the phosphor for near ultraviolet (n-UV) LEDs. A 3-phosphor-conversion w-LED lamp was fabricated with the as-prepared phosphor, which exhibits high CRI (Ra = 85.29) and suitable CCT (4903.35 K). All these results indicate that the Ca 3 Si 3-x O 3+x N 4-2x : Eu 2+ phosphor can serve as the green phosphor for n-UV w-LEDs, with a tunable spectrum by controlling the crystal structure and morphology.

Update on Heavy-Meson Spectrum Tests of the Oktay--Kronfeld Action

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

Bailey, Jon A.; Jang, Yong-Chull; Lee, Weonjong

2016-01-18

We present updated results of a numerical improvement test with heavy-meson spectrum for the Oktay--Kronfeld (OK) action. The OK action is an extension of the Fermilab improvement program for massive Wilson fermions including all dimension-six and some dimension-seven bilinear terms. Improvement terms are truncated by HQET power counting atmore » $$\\mathrm{O}(\\Lambda^3/m_Q^3)$$ for heavy-light systems, and by NRQCD power counting at $$\\mathrm{O}(v^6)$$ for quarkonium. They suffice for tree-level matching to QCD to the given order in the power-counting schemes. To assess the improvement, we generate new data with the OK and Fermilab action that covers both charm and bottom quark mass regions on a MILC coarse $$(a \\approx 0.12~\\text{fm})$$ $2+1$ flavor, asqtad-staggered ensemble. We update the analyses of the inconsistency quantity and the hyperfine splittings for the rest and kinetic masses. With one exception, the results clearly show that the OK action significantly reduces heavy-quark discretization effects in the meson spectrum. The exception is the hyperfine splitting of the heavy-light system near the $$B_s$$ meson mass, where statistics are too low to draw a firm conclusion, despite promising results.« less

Features of the Percolation Scheme of Vibrational Spectrum Reconstruction in the Ga1 - x Al x P Alloy

NASA Astrophysics Data System (ADS)

Kozyrev, S. P.

2018-04-01

Specific features of the properties of Ga-P lattice vibrations have been investigated using the percolation model of a mixed Ga1 - x Al x P crystal (alloy) with zero lattice mismatch between binary components of the alloy. In contrast to other two-mode alloy systems, in Ga1 - x Al x P a percolation splitting of δ 13 cm-1 is observed for the low-frequency mode of GaP-like vibrations. An additional GaP mode (one of the percolation doublet components) split from the fundamental mode is observed for the GaP-rich alloy, which coincides in frequency with the gap corresponding to the zero density of one-phonon states of the GaP crystal. The vibrational spectrum of impurity Al in the GaP crystal has been calculated using the theory of crystal lattice dynamics. Upon substitution of lighter Al for the Ga atom, the calculated spectrum includes, along with the local mode, a singularity near the gap with the zero density of phonon states of the GaP crystal, which coincides with the mode observed experimentally at a frequency of 378 cm-1 in the Ga1 - x Al x P ( x < 0.4) alloy.

Contrast-enhanced dual-energy subtraction imaging using electronic spectrum-splitting and multi-prism x-ray lenses

NASA Astrophysics Data System (ADS)

Fredenberg, Erik; Cederström, Björn; Lundqvist, Mats; Ribbing, Carolina; Åslund, Magnus; Diekmann, Felix; Nishikawa, Robert; Danielsson, Mats

2008-03-01

Dual-energy subtraction imaging (DES) is a method to improve the detectability of contrast agents over a lumpy background. Two images, acquired at x-ray energies above and below an absorption edge of the agent material, are logarithmically subtracted, resulting in suppression of the signal from the tissue background and a relative enhancement of the signal from the agent. Although promising, DES is still not widely used in clinical practice. One reason may be the need for two distinctly separated x-ray spectra that are still close to the absorption edge, realized through dual exposures which may introduce motion unsharpness. In this study, electronic spectrum-splitting with a silicon-strip detector is theoretically and experimentally investigated for a mammography model with iodinated contrast agent. Comparisons are made to absorption imaging and a near-ideal detector using a signal-to-noise ratio that includes both statistical and structural noise. Similar to previous studies, heavy absorption filtration was needed to narrow the spectra at the expense of a large reduction in x-ray flux. Therefore, potential improvements using a chromatic multi-prism x-ray lens (MPL) for filtering were evaluated theoretically. The MPL offers a narrow tunable spectrum, and we show that the image quality can be improved compared to conventional filtering methods.

Large object investigation by digital holography with effective spectrum multiplexing under single-exposure approach

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

Liu, Ning, E-mail: coolboy006@sohu.com; Zhang, Yingying; Xie, Jun

2014-10-13

We present a method to investigate large object by digital holography with effective spectrum multiplexing under single-exposure approach. This method splits the original reference beam and redirects one of its branches as a second object beam. Through the modified Mach-Zehnder interferometer, the two object beams can illuminate different parts of the large object and create a spectrum multiplexed hologram onto the focal plane array of the charge-coupled device/complementary metal oxide semiconductor camera. After correct spectrum extraction and image reconstruction, the large object can be fully observed within only one single snap-shot. The flexibility and great performance make our method amore » very attractive and promising technique for large object investigation under common 632.8 nm illumination.« less

Metabolic engineering to expand the substrate spectrum of Pseudomonas putida toward sucrose.

PubMed

Löwe, Hannes; Schmauder, Lukas; Hobmeier, Karina; Kremling, Andreas; Pflüger-Grau, Katharina

2017-08-01

Sucrose is an important disaccharide used as a substrate in many industrial applications. It is a major component of molasses, a cheap by-product of the sugar industry. Unfortunately, not all industrially relevant organisms, among them Pseudomonas putida, are capable of metabolizing sucrose. We chose a metabolic engineering approach to circumvent this blockage and equip P. putida with the activities necessary to consume sucrose. Therefore, we constructed a pair of broad-host range mini-transposons (pSST - sucrose splitting transposon), carrying either cscA, encoding an invertase able to split sucrose into glucose and fructose, or additionally cscB, encoding a sucrose permease. Introduction of cscA was sufficient to convey sucrose consumption and the additional presence of cscB had no further effect, though the sucrose permease was built and localized to the membrane. Sucrose was split extracellularly by the activity of the invertase CscA leaking out of the cell. The transposons were also used to confer sucrose consumption to Cupriavidus necator. Interestingly, in this strain, CscB acted as a glucose transporter, such that C. necator also gained the ability to grow on glucose. Thus, the pSST transposons are functional tools to extend the substrate spectrum of Gram-negative bacterial strains toward sucrose. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Microwave Spectroscopy of 2-PENTANONE

NASA Astrophysics Data System (ADS)

Andresen, Maike; Nguyen, Ha Vinh Lam; Kleiner, Isabelle; Stahl, Wolfgang

2017-06-01

Methyl propyl ketone (MPK) or 2-Pentanone is known to be an alarm pheroromone released by the mandibular glands of the bees. It is a highly volatile compound. This molecule was studied by a combination of quantum chemical calculations and microwave spectroscopy in order to get informations about the lowest energy conformers and their structures.The rotational spectrum of 2-pentanone was measured using the molecular beam Fourier transform microwave spectrometer in Aachen operating between 2 and 26.5 GHz. Ab initio calculations determine 4 conformers but only two of them are observed in our jet-beam conditions.The lowest conformer has a C_{1} structure and its spectrum shows internal rotation splittings arising from two methyl groups. The internal splittings of 305 transitions for this conformer were analyzed using the XIAM code It led to the determination of the values for the barrier heights hindering the internal rotation of two methyl groups of 239 cm^{-1} and 980 cm^{-1} respectively. The next energy conformer has a C_{s} structure and the analysis of the internal splittings of 134 transitions using the XIAM code and the BELGI code led to the determination of internal rotation barrier height of 186 cm^{-1}. Comparisons of quantum chemistry and experimental results will be discussed. H. Hartwig, H. Dreizler, Z. Naturforsch. 51a, 923 (1996). J. T. Hougen, I. Kleiner and M. Godefroid, J. Mol. Spectrosc., 163, 559-586 (1994).

Magneto-optical spectrum and the effective excitonic Zeeman splitting energies of Mn and Co-doped CdSe nanowires

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

Xiong, Wen, E-mail: wenxiong@cqu.edu.cn; Chen, Wensuo

2013-12-21

The electronic structure of Mn and Co-doped CdSe nanowires are calculated based on the six-band k·p effective-mass theory. Through the calculation, it is found that the splitting energies of the degenerate hole states in Mn-doped CdSe nanowires are larger than that in Co-doped CdSe nanowires when the concentration of these two kinds of magnetic ions is the same. In order to analysis the magneto-optical spectrum of Mn and Co-doped CdSe nanowires, the four lowest electron states and the four highest hole states are sorted when the magnetic field is applied, and the 10 lowest optical transitions between the conduction subbandsmore » and the valence subbands at the Γ point in Mn and Co-doped CdSe nanowires are shown in the paper, it is found that the order of the optical transitions at the Γ point almost do not change although two different kinds of magnetic ions are doped in CdSe nanowires. Finally, the effective excitonic Zeeman splitting energies at the Γ point are found to increase almost linearly with the increase of the concentration of the magnetic ions and the magnetic field; meanwhile, the giant positive effective excitonic g factors in Mn and Co-doped CdSe nanowires are predicted based on our theoretical calculation.« less

Electronic spectrum of trilayer graphene

NASA Astrophysics Data System (ADS)

Kumar, S.; Ajay

2014-08-01

Present work deals with the analysis of the single particle electronic spectral function in trilayer (ABC-, ABA- and AAA-stacked) graphene. Tight binding Hamiltonian containing intralayer nearest-neighbor and next-nearest neighbor hopping along-with the interlayer coupling parameter within two triangular sub-lattice approach for trilayer graphene has been employed. The expression of single particle spectral functions A(kw) is obtained within mean-field Green's function equations of motion approach. Spectral function at Γ, M and K points of the Brillouin zone has been numerically computed. It is pointed out that the nature of electronic states at different points of Brillouin zone is found to be influenced by stacking order and Coulomb interactions. At Γ and M points, a trilayer splitting is predicted while at K point a bilayer splitting effect is observed due to crossing of two bands (at K point). Interlayer coupling ( t_{ bot } ) is found to be responsible for the splitting of quasi-particle peaks at each point of Brillouin zone. The influence of t_{ bot } in trilayer graphene is prominent for AAA-stacking compared to ABC- and ABA-stacking. On the other hand, onsite Coulomb interaction reduces the trilayer splitting effect into bilayer splitting at Γ and M points of Brillouin zone and bilayer splitting into single peak spectral function at K point with a shifting of the peak away from Fermi level.

The EEG Split Alpha Peak: Phenomenological Origins and Methodological Aspects of Detection and Evaluation.

PubMed

Olejarczyk, Elzbieta; Bogucki, Piotr; Sobieszek, Aleksander

2017-01-01

Electroencephalographic (EEG) patterns were analyzed in a group of ambulatory patients who ranged in age and sex using spectral analysis as well as Directed Transfer Function, a method used to evaluate functional brain connectivity. We tested the impact of window size and choice of reference electrode on the identification of two or more peaks with close frequencies in the spectral power distribution, so called "split alpha." Together with the connectivity analysis, examination of spatiotemporal maps showing the distribution of amplitudes of EEG patterns allowed for better explanation of the mechanisms underlying the generation of split alpha peaks. It was demonstrated that the split alpha spectrum can be generated by two or more independent and interconnected alpha wave generators located in different regions of the cerebral cortex, but not necessarily in the occipital cortex. We also demonstrated the importance of appropriate reference electrode choice during signal recording. In addition, results obtained using the original data were compared with results obtained using re-referenced data, using average reference electrode and reference electrode standardization techniques.

Investigation of the Presence of Charge Order in Magnetite by Measurement of the Sprin Wave Spectrum

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

McQueeny, R. J.; Yethiraj, Mohana; Montfrooij, W.

Inelastic neutron scattering results on magnetite (Fe{sub 3}O{sub 4}) show a large splitting in the acoustic spin wave branch, producing a 7 meV gap midway to the Brillouin zone boundary at q = (0,0,1/2) and {h_bar}{omega} = 43 meV. The splitting occurs below the Verwey transition temperature, where a metal-insulator transition occurs simultaneously with a structural transformation, supposedly caused by the charge ordering on the iron sublattice. The wavevector (0,0,1/2) corresponds to the superlattice peak in the low symmetry structure. The dependence of the magnetic superexchange on changes in the crystal structure and ionic configurations that occur below the Verweymore » transition affect the spin wave dispersion. To better understand the origin of the observed splitting, several Heisenberg models intended to reproduce the pair-wise variation of the magnetic superexchange arising from both small crystalline distortions and charge ordering were studied. None of the models studied predicts the observed splitting, whose origin may arise from charge-density wave formation or magnetoelastic coupling.« less

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

Zhai, Yaxin; Baniya, Sangita; Zhang, Chuang

Two-dimensional (2D) layered hybrid organic-inorganic halide perovskite semiconductors form natural “multiple quantum wells” that have strong spin-orbit coupling due to the heavy elements in their building blocks. This may lead to “Rashba splitting” close to the extrema in the electron bands. We have used a plethora of ultrafast transient, nonlinear optical spectroscopies and theoretical calculations to study the primary (excitons) and long-lived (free carriers) photoexcitations in thin films of 2D perovskite, namely, (C 6H 5C 2H 4NH 3) 2PbI 4. The density functional theory calculation shows the occurrence of Rashba splitting in the plane perpendicular to the 2D barrier. Frommore » the electroabsorption spectrum and photoinduced absorption spectra from excitons and free carriers, we obtain a giant Rashba splitting in this compound, with energy splitting of (40 ± 5) meV and Rashba parameter of (1.6 ± 0.1) eV·Å, which are among the highest Rashba splitting size parameters reported so far. In conclusion, this finding shows that 2D hybrid perovskites have great promise for potential applications in spintronics.« less

EPR, optical and modeling of Mn(2+) doped sarcosinium oxalate monohydrate.

PubMed

Kripal, Ram; Singh, Manju

2015-01-25

Electron paramagnetic resonance (EPR) study of Mn(2+) ions doped in sarcosinium oxalate monohydrate (SOM) single crystal is done at liquid nitrogen temperature (LNT). EPR spectrum shows a bunch of five fine structure lines and further they split into six hyperfine components. Only one interstitial site was observed. With the help of EPR spectra the spin Hamiltonian parameters including zero field splitting (ZFS) parameters are evaluated. The optical absorption study at room temperature is also done in the wavelength range 195-1100 nm. From this study cubic crystal field splitting parameter, Dq=730 cm(-1) and Racah inter-electronic repulsion parameters B=792 cm(-1), C=2278 cm(-1) are determined. ZFS parameters D and E are also calculated using crystal field parameters from superposition model and microscopic spin Hamiltonian theory. The calculated ZFS parameter values are in good match with the experimental values obtained by EPR. Copyright © 2014 Elsevier B.V. All rights reserved.

A search for muon neutrino to electron neutrino oscillation mediated by sterile neutrinos in MINOS+

NASA Astrophysics Data System (ADS)

Germani, Stefano; Schreckenberger, Adam P.

2017-09-01

The MINOS experiment made precision measurements of the neutrino oscillation parameters that are governed by the atmospheric mass-squared splitting. These measurements were made with data that were collected while the NuMI muon neutrino beam operated in a low energy mode that peaks around 3 GeV. Today the NuMI beam is running with a higher energy mode that produces a neutrino energy spectrum that peaks around 7 GeV, allowing the MINOS+ experiment to probe neutrino oscillation phenomena that could potentially be governed by a fourth mass-squared splitting. If observed, the presence of a fourth mass-squared splitting would be compelling evidence for a sterile neutrino state. In this analysis, we will present the results of a search for νµ → νe oscillation mediated by sterile neutrinos in MINOS+. The results will be contrasted against the measurements made by the LSND experiment.

Robust exciton-polariton Rabi splitting in graphene nano ribbons: the means of two-coupled semiconductor microcavities

NASA Astrophysics Data System (ADS)

Imannezhad, Sanaz; Shojaei, Saeid

2018-04-01

Recent work on the exciton-photon coupling is presented. The proposed structure is a two-coupled semiconductor microcavity, composed of distributed Bragg reflectors, each consists of Si3N4 / SiO2, AlAs / Al0.1Ga0.9As, and GaAs/AlAs. Assuming that armchair graphene nanoribbon is located in the maximum of electric field amplitude inside the first semiconductor microcavity, the transfer matrix method is used to obtain the upper and lower polariton (UP and LP) branches and angle-dependent reflectance spectrum. A clear anticrossing between the neutral excitons and the cavity modes is observed for different polarization states. The obtained magnitude of splitting from the results is 10 to 12 meV, which indicates the possibility of enhancing the vacuum Rabi splitting for the proposed structure. This can pave the ways toward implementation of graphene in polaritonic devices.

Polarized fine structure in the photoluminescence excitation spectrum of a negatively charged quantum dot.

PubMed

Ware, M E; Stinaff, E A; Gammon, D; Doty, M F; Bracker, A S; Gershoni, D; Korenev, V L; Bădescu, S C; Lyanda-Geller, Y; Reinecke, T L

2005-10-21

We report polarized photoluminescence excitation spectroscopy of the negative trion in single charge-tunable quantum dots. The spectrum exhibits a p-shell resonance with polarized fine structure arising from the direct excitation of the electron spin triplet states. The energy splitting arises from the axially symmetric electron-hole exchange interaction. The magnitude and sign of the polarization are understood from the spin character of the triplet states and a small amount of quantum dot asymmetry, which mixes the wave functions through asymmetric e-e and e-h exchange interactions.

Proceedings of the RADC Spectrum Estimation Workshop (2nd) held 3, 4, & 5 October 1979, Griffiss AFB, NY

DTIC Science & Technology

1979-10-01

However, this author’s ex- perience has shown that most order selection rules , including Akaike’s, are not enough to be effeutive against the line splitting...and reduced spectral peak frequency estimation biases. A set of sensitive stopping rules for order se- L lection has been found for the algorithm...7] as the rule for order selection, the minimum FPE of the 41-point sequence with tne Burg algorithm was found at order 23. The AR spectrum based on

Raman-Ramsey multizone spectroscopy in a pure rubidium vapor cell

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

Failache, H.; Lenci, L.; Lezama, A.

2010-02-15

In view of application to a miniaturized spectroscopy system, we consider an optical setup that splits a laser beam into several parallel narrow light sheets allowing an effective beam expansion and consequently longer atom-light interaction times. We analyze the multizone coherent population trapping (MZCPT) spectroscopy of alkali-metal-vapor atoms, without buffer gas, in the presence of a split light beam. We show that the MZCPT signal is largely insensitive to intensity broadening. Experimentally observed spectra are in qualitative agreement with the predictions of a simplified model that describes each spectrum as an integral over the atomic velocity distribution of Ramsey multizonemore » spectra.« less

Deep subwavelength fourfold rotationally symmetric split-ring-resonator metamaterials for highly sensitive and robust biosensing platform

PubMed Central

Tobing, Landobasa Y. M.; Tjahjana, Liliana; Zhang, Dao Hua; Zhang, Qing; Xiong, Qihua

2013-01-01

Metamaterials provide a good platform for biochemical sensing due to its strong field localization at nanoscale. In this work, we show that electric and magnetic resonant modes in split-ring-resonator (SRR) can be efficiently excited under unpolarized light illumination when the SRRs are arranged in fourfold rotationally symmetric lattice configuration. The fabrication and characterization of deep subwavelength (~λ/15) gold-based SRR structures with resonator size as small as ~ 60 nm are reported with magnetic resonances in Vis-NIR spectrum range. The feasibility for sensing is demonstrated with refractive index sensitivity as high as ~ 636 nm/RIU. PMID:23942416

Study of distorted octahedral structure in 3d transition metal complexes using XAFS

NASA Astrophysics Data System (ADS)

Gaur, A.; Nitin Nair, N.; Shrivastava, B. D.; Das, B. K.; Chakrabortty, Monideepa; Jha, S. N.; Bhattacharyya, D.

2018-01-01

Distortion in octahedral structure of 3d transition metal complexes (Mn, Fe, Co, Ni, Cu, Zn) has been studied using XAFS showing divergent nature of Cu complex. EXAFS analysis showed elongated metal-oxygen bonds for Cu complex leading to more distorted structure. Derivative XANES spectrum at Cu K-edge exhibits splitting of main edge which is correlated to elongated Cu-O bond length. Using these coordination geometry around metal centers, theoretical XANES spectra have been generated and features observed have been correlated to the corresponding metals p-DOS. It has been shown that distorted octahedral field in Cu complex is responsible for splitting of p-DOS.

Determination of Torsional Barriers of Itaconic Acid and N-Acetylethanolamine Using Chirped-Pulsed Ftmw Spectroscopy

NASA Astrophysics Data System (ADS)

Bailey, Josiah R.; McMahon, Timothy J.; Bird, Ryan G.; Pratt, David

2015-06-01

The ground state rotational spectrum of itaconic acid (methylenesuccinic acid) and N-acetylethanolamine (AEA) have been collected and analyzed over the frequency range of 7-17.5 GHz. Both molecules displayed an unexpected tunneling splitting pattern caused by a V2 and V3 barriers, respectively. AEA's methyl rotor is directly connected to a carbonyl and is expected to have too high of a barrier to internal motion. Itaconic acid contains no methyl groups or any symmetry, yet a torsional splitting was observed. The origin of this motion as well their barrier heights and lowest energy conformations will be discussed.

Highly Active GaN-Stabilized Ta3 N5 Thin-Film Photoanode for Solar Water Oxidation.

PubMed

Zhong, Miao; Hisatomi, Takashi; Sasaki, Yutaka; Suzuki, Sayaka; Teshima, Katsuya; Nakabayashi, Mamiko; Shibata, Naoya; Nishiyama, Hiroshi; Katayama, Masao; Yamada, Taro; Domen, Kazunari

2017-04-18

Ta 3 N 5 is a very promising photocatalyst for solar water splitting because of its wide spectrum solar energy utilization up to 600 nm and suitable energy band position straddling the water splitting redox reactions. However, its development has long been impeded by poor compatibility with electrolytes. Herein, we demonstrate a simple sputtering-nitridation process to fabricate high-performance Ta 3 N 5 film photoanodes owing to successful synthesis of the vital TaO δ precursors. An effective GaN coating strategy is developed to remarkably stabilize Ta 3 N 5 by forming a crystalline nitride-on-nitride structure with an improved nitride/electrolyte interface. A stable, high photocurrent density of 8 mA cm -2 was obtained with a CoPi/GaN/Ta 3 N 5 photoanode at 1.2 V RHE under simulated sunlight, with O 2 and H 2 generated at a Faraday efficiency of unity over 12 h. Our vapor-phase deposition method can be used to fabricate high-performance (oxy)nitrides for practical photoelectrochemical applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectroscopic Characterization, Computational Investigation, and Comparisons of ECX – (E = As, P, and N; X = S and O) Anions

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

Hou, Gao-Lei; Chen, Bo; Transue, Wesley J.

Three newly-synthesized [Na+(221-kryptofix)] salts containing AsCO–, PCO–, and PCS– anions were successfully electrosprayed into the vacuum, and the ECX– (E = As, P; X = O, S) anions were investigated by negative ion photoelectron spectroscopy (NIPES) and high resolution photoelectron imaging spectroscopy. For each ECX– anion, a well-resolved NIPE spectrum was obtained, in which every major peak is split into a doublet. The splittings are attributed to spin-orbit coupling (SOC) in the ECX• radicals. Vibrational progressions in the NIPE spectra of ECX– were assigned to the symmetric and antisymmetric stretching modes in ECX• radicals. The electron affinities (EAs) and SOCmore » splittings of ECX• are determined from the NIPE spectra to be: AsCO•: EA = 2.414 ± 0.002 eV, SOC splitting = 988 cm-1; PCO•: EA = 2.670 ± 0.005 eV, SOC splitting = 175 cm-1; PCS•: EA = 2.850 ± 0.005 eV, SOC splitting = 300 cm-1. Calculations using the B3LYP, CASPT2, and CCSD(T) methods all predict linear geometries for both the anions and neutral radicals. The calculated EAs and SOC splittings for ECX• are in excellent agreement with the experimentally-measured values. The simulated NIPE spectra, based on the calculated Franck-Condon factors, and SOC splittings nicely reproduce all of the observed spectral peaks, thus allowing unambiguous spectral assignments. The finding that PCS has the greatest EA of the three triatomic molecules considered here is counterintuitive based upon electronegativity considerations, but understandable in terms of the HOMO of PCS– having the greatest degree of delocalization onto both terminal atoms.« less

Techniques and Tools for Estimating Ionospheric Effects in Interferometric and Polarimetric SAR Data

NASA Technical Reports Server (NTRS)

Rosen, P.; Lavalle, M.; Pi, X.; Buckley, S.; Szeliga, W.; Zebker, H.; Gurrola, E.

2011-01-01

The InSAR Scientific Computing Environment (ISCE) is a flexible, extensible software tool designed for the end-to-end processing and analysis of synthetic aperture radar data. ISCE inherits the core of the ROI_PAC interferometric tool, but contains improvements at all levels of the radar processing chain, including a modular and extensible architecture, new focusing approach, better geocoding of the data, handling of multi-polarization data, radiometric calibration, and estimation and correction of ionospheric effects. In this paper we describe the characteristics of ISCE with emphasis on the ionospheric modules. To detect ionospheric anomalies, ISCE implements the Faraday rotation method using quadpolarimetric images, and the split-spectrum technique using interferometric single-, dual- and quad-polarimetric images. The ability to generate co-registered time series of quad-polarimetric images makes ISCE also an ideal tool to be used for polarimetric-interferometric radar applications.

Quadrupole splittings in the near-infrared spectrum of 14NH 3

DOE PAGES

Twagirayezu, Sylvestre; Hall, Gregory E.; Sears, Trevor J.

2016-10-13

Sub-Doppler, saturation dip, spectra of lines in the v 1 + v 3, v 1 + 2v 4 and v 3 + 2v 4 bands of 14NH 3 have been measured by frequency comb-referenced diode laser absorption spectroscopy. The observed spectral line widths are dominated by transit time broadening, and show resolved or partially-resolved hyperfine splittings that are primarily determined by the 14N quadrupole coupling. Modeling of the observed line shapes based on the known hyperfine level structure of the ground state of the molecule shows that, in nearly all cases, the excited state level has hyperfine splittings similar tomore » the same rotational level in the ground state. The data provide accurate frequencies for the line positions and easily separate lines overlapped in Doppler-limited spectra. The observed hyperfine splittings can be used to make and confirm rotational assignments and ground state combination differences obtained from the measured frequencies are comparable in accuracy to those obtained from conventional microwave spectroscopy. Furthermore, several of the measured transitions do not show the quadrupole hyperfine splittings expected based on their existing rotational assignments. Either the assignments are incorrect or the upper levels involved are perturbed in a way that affects the nuclear hyperfine structure.« less

Intraband magneto-optical absorption in InAs/GaAs quantum dots: Orbital Zeeman splitting and the Thomas-Reiche-Kuhn sum rule

NASA Astrophysics Data System (ADS)

Zhang, J.-Z.; Galbraith, I.

2008-05-01

Using perturbation theory, intraband magneto-optical absorption is calculated for InAs/GaAs truncated pyramidal quantum dots in a magnetic field applied parallel to the growth direction z . The effects of the magnetic field on the electronic states as well as the intraband transitions are systematically studied. Selection rules governing the intraband transitions are discussed based on the symmetry properties of the electronic states. While the broadband z -polarized absorption is almost insensitive to the magnetic field, the orbital Zeeman splitting is the dominant feature in the in-plane polarized spectrum. Strong in-plane polarized magneto-absorption features are located in the far-infrared region, while z -polarized absorption occurs at higher frequencies. This is due to the dot geometry (the base length is much larger than the height) yielding different quantum confinement in the vertical and lateral directions. The Thomas-Reiche-Kuhn sum rule, including the magnetic field effect, is applied together with the selection rules to the absorption spectra. The orbital Zeeman splitting depends on both the dot size and the confining potential—the splitting decreases as the dot size or the confining potential decreases. Our calculated Zeeman splittings are in agreement with experimental data.

Splitting algorithm for numerical simulation of Li-ion battery electrochemical processes

NASA Astrophysics Data System (ADS)

Iliev, Oleg; Nikiforova, Marina A.; Semenov, Yuri V.; Zakharov, Petr E.

2017-11-01

In this paper we present a splitting algorithm for a numerical simulation of Li-ion battery electrochemical processes. Liion battery consists of three domains: anode, cathode and electrolyte. Mathematical model of electrochemical processes is described on a microscopic scale, and contains nonlinear equations for concentration and potential in each domain. On the interface of electrodes and electrolyte there are the Lithium ions intercalation and deintercalation processes, which are described by Butler-Volmer nonlinear equation. To approximate in spatial coordinates we use finite element methods with discontinues Galerkin elements. To simplify numerical simulations we develop the splitting algorithm, which split the original problem into three independent subproblems. We investigate the numerical convergence of the algorithm on 2D model problem.

Analysis of operator splitting errors for near-limit flame simulations

NASA Astrophysics Data System (ADS)

Lu, Zhen; Zhou, Hua; Li, Shan; Ren, Zhuyin; Lu, Tianfeng; Law, Chung K.

2017-04-01

High-fidelity simulations of ignition, extinction and oscillatory combustion processes are of practical interest in a broad range of combustion applications. Splitting schemes, widely employed in reactive flow simulations, could fail for stiff reaction-diffusion systems exhibiting near-limit flame phenomena. The present work first employs a model perfectly stirred reactor (PSR) problem with an Arrhenius reaction term and a linear mixing term to study the effects of splitting errors on the near-limit combustion phenomena. Analysis shows that the errors induced by decoupling of the fractional steps may result in unphysical extinction or ignition. The analysis is then extended to the prediction of ignition, extinction and oscillatory combustion in unsteady PSRs of various fuel/air mixtures with a 9-species detailed mechanism for hydrogen oxidation and an 88-species skeletal mechanism for n-heptane oxidation, together with a Jacobian-based analysis for the time scales. The tested schemes include the Strang splitting, the balanced splitting, and a newly developed semi-implicit midpoint method. Results show that the semi-implicit midpoint method can accurately reproduce the dynamics of the near-limit flame phenomena and it is second-order accurate over a wide range of time step size. For the extinction and ignition processes, both the balanced splitting and midpoint method can yield accurate predictions, whereas the Strang splitting can lead to significant shifts on the ignition/extinction processes or even unphysical results. With an enriched H radical source in the inflow stream, a delay of the ignition process and the deviation on the equilibrium temperature are observed for the Strang splitting. On the contrary, the midpoint method that solves reaction and diffusion together matches the fully implicit accurate solution. The balanced splitting predicts the temperature rise correctly but with an over-predicted peak. For the sustainable and decaying oscillatory combustion from cool flames, both the Strang splitting and the midpoint method can successfully capture the dynamic behavior, whereas the balanced splitting scheme results in significant errors.

Analysis of operator splitting errors for near-limit flame simulations

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

Lu, Zhen; Zhou, Hua; Li, Shan

High-fidelity simulations of ignition, extinction and oscillatory combustion processes are of practical interest in a broad range of combustion applications. Splitting schemes, widely employed in reactive flow simulations, could fail for stiff reaction–diffusion systems exhibiting near-limit flame phenomena. The present work first employs a model perfectly stirred reactor (PSR) problem with an Arrhenius reaction term and a linear mixing term to study the effects of splitting errors on the near-limit combustion phenomena. Analysis shows that the errors induced by decoupling of the fractional steps may result in unphysical extinction or ignition. The analysis is then extended to the prediction ofmore » ignition, extinction and oscillatory combustion in unsteady PSRs of various fuel/air mixtures with a 9-species detailed mechanism for hydrogen oxidation and an 88-species skeletal mechanism for n-heptane oxidation, together with a Jacobian-based analysis for the time scales. The tested schemes include the Strang splitting, the balanced splitting, and a newly developed semi-implicit midpoint method. Results show that the semi-implicit midpoint method can accurately reproduce the dynamics of the near-limit flame phenomena and it is second-order accurate over a wide range of time step size. For the extinction and ignition processes, both the balanced splitting and midpoint method can yield accurate predictions, whereas the Strang splitting can lead to significant shifts on the ignition/extinction processes or even unphysical results. With an enriched H radical source in the inflow stream, a delay of the ignition process and the deviation on the equilibrium temperature are observed for the Strang splitting. On the contrary, the midpoint method that solves reaction and diffusion together matches the fully implicit accurate solution. The balanced splitting predicts the temperature rise correctly but with an over-predicted peak. For the sustainable and decaying oscillatory combustion from cool flames, both the Strang splitting and the midpoint method can successfully capture the dynamic behavior, whereas the balanced splitting scheme results in significant errors.« less

Roll splitting for field processing of biomass

Treesearch

Dennis T. Curtin; Donald L. Sirois; John A. Sturos

1987-01-01

The concept of roll splitting wood originated in 1967 when the Tennessee Valley Authority (TVA) forest products specialists developed a wood fibrator. The objective of that work was to produce raw materials for reconstituted board products. More recently, TVA focused on roll splitting as a field process to accelerate drying of small trees (3-15 cm diameter), much...

Robust frequency diversity based algorithm for clutter noise reduction of ultrasonic signals using multiple sub-spectrum phase coherence

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

Gongzhang, R.; Xiao, B.; Lardner, T.

2014-02-18

This paper presents a robust frequency diversity based algorithm for clutter reduction in ultrasonic A-scan waveforms. The performance of conventional spectral-temporal techniques like Split Spectrum Processing (SSP) is highly dependent on the parameter selection, especially when the signal to noise ratio (SNR) is low. Although spatial beamforming offers noise reduction with less sensitivity to parameter variation, phased array techniques are not always available. The proposed algorithm first selects an ascending series of frequency bands. A signal is reconstructed for each selected band in which a defect is present when all frequency components are in uniform sign. Combining all reconstructed signalsmore » through averaging gives a probability profile of potential defect position. To facilitate data collection and validate the proposed algorithm, Full Matrix Capture is applied on the austenitic steel and high nickel alloy (HNA) samples with 5MHz transducer arrays. When processing A-scan signals with unrefined parameters, the proposed algorithm enhances SNR by 20dB for both samples and consequently, defects are more visible in B-scan images created from the large amount of A-scan traces. Importantly, the proposed algorithm is considered robust, while SSP is shown to fail on the austenitic steel data and achieves less SNR enhancement on the HNA data.« less

Anisotropic magnetohydrodynamic turbulence in a strong external magnetic field

NASA Technical Reports Server (NTRS)

Montgomery, D.; Turner, L.

1981-01-01

A strong external dc magnetic field introduces a basic anisotropy into incompressible magnetohydrodynamic turbulence. The modifications that this is likely to produce in the properties of the turbulence are explored for the high Reynolds number case. The conclusion is reached that the turbulent spectrum splits into two parts: an essentially two dimensional spectrum with both the velocity field and magnetic fluctuations perpendicular to the dc magnetic field, and a generally weaker and more nearly isotropic spectrum of Alfven waves. A minimal characterization of the spectral density tensors is given. Similarities to measurements from the Culham-Harwell Zeta pinch device and the UCLA Macrotor Tokamak are remarked upon, as are certain implications for the Belcher and Davis measurements of magnetohydrodynamic turbulence in the solar wind.

Retrofitted supersymmetric models

NASA Astrophysics Data System (ADS)

Bose, Manatosh

This thesis explores several models of metastable dynamic supersymmetry breaking (MDSB) and a supersymmetric model of hybrid inflation. All of these models possess discrete R-symmetries. We specially focus on the retrofitted models for supersymmetry breaking models. At first we construct retrofitted models of gravity mediation. In these models we explore the genericity of the so-called "split supersymmetry." We show that with the simplest models, where the goldstino multiplet is neutral under the discrete R-symmetry, a split spectrum is not generic. However if the goldstino superfield is charged under some symmetry other than the R-symmetry, then a split spectrum is achievable but not generic. We also present a gravity mediated model where the fine tuning of the Z-boson mass is dictated by a discrete choice rather than a continuous tuning. Then we construct retrofitted models of gauge mediated SUSY breaking. We show that, in these models, if the approximate R-symmetry of the theory is spontaneously broken, the messenger scale is fixed; if explicitly broken by retrofitted couplings, a very small dimensionless number is required; if supergravity corrections are responsible for the symmetry breaking, at least two moderately small couplings are required, and that there is a large range of possible messenger scales. Finally we switch our attention to small field hybrid inflation. We construct a model that yields a spectral index ns = 0.96. Here, we also briefly discuss the possibility of relating the scale of inflation with the dynamics responsible for supersymmetry breaking.

Quantum plasmon and Rashba-like spin splitting in self-assembled Co x C60 composites with enhanced Co content (x > 15)

NASA Astrophysics Data System (ADS)

Lavrentiev, Vasily; Chvostova, Dagmar; Stupakov, Alexandr; Lavrentieva, Inna; Vacik, Jiri; Motylenko, Mykhaylo; Barchuk, Mykhailo; Rafaja, David; Dejneka, Alexandr

2018-04-01

Driving by interplay between plasmonic and magnetic effects in organic composite semiconductors is a challenging task with a huge potential for practical applications. Here, we present evidence of a quantum plasmon excited in the self-assembled Co x C60 nanocomposite films with x > 15 (interval of the Co cluster coalescence) and analyse it using the optical absorption (OA) spectra. In the case of Co x C60 film with x = 16 (LF sample), the quantum plasmon generated by the Co/CoO clusters is found as the 1.5 eV-centred OA peak. This finding is supported by the establishment of four specific C60-related OA lines detected at the photon energies E p > 2.5 eV. Increase of the Co content up to x = 29 (HF sample) leads to pronounced enhancement of OA intensity in the energy range of E p > 2.5 eV and to plasmonic peak downshift of 0.2 eV with respect to the peak position in the LF spectrum. Four pairs of the OA peaks evaluated in the HF spectrum at E p > 2.5 eV reflect splitting of the C60-related lines, suggesting great change in the microscopic conditions with increasing x. Analysis of the film nanostructure and the plasmon-induced conditions allows us to propose a Rashba-like spin splitting effect that suggests valuable sources for spin polarization.

Single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides as promising photocatalysts.

PubMed

Bai, Yujie; Luo, Gaixia; Meng, Lijuan; Zhang, Qinfang; Xu, Ning; Zhang, Haiyang; Wu, Xiuqiang; Kong, Fanjie; Wang, Baolin

2018-05-30

Searching for two-dimensional semiconductor materials that are suitable for visible-light photocatalytic water splitting provides a sustainable solution to deal with the future energy crisis and environmental problems. Herein, based on first-principles calculations, single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides are proposed as efficient photocatalysts for water splitting. Stability analyses show that the single-layer ZnMN2 zinc nitrides exhibit energetic and dynamical stability. The electronic properties reveal that all of the single-layer ZnMN2 zinc nitrides are semiconductors. Interestingly, single-layer ZnSnN2 is a direct band gap semiconductor with a desirable band gap (1.74 eV), and the optical adsorption spectrum confirms its optical absorption in the visible light region. The hydrogen evolution reaction (HER) calculations show that the catalytic activity for single-layer ZnMN2 (M = Ge, Sn) is better than that of single-layer ZnSiN2. Furthermore, the band gaps and band edge positions for the single-layer ZnMN2 zinc nitrides can be effectively tuned by biaxial strain. Especially, single-layer ZnGeN2 can be effectively tuned to match better with the redox potentials of water and enhance the light absorption in the visible light region at a tensile strain of 5%, which is confirmed by the corresponding optical absorption spectrum. Our results provide guidance for experimental synthesis efforts and future searches for single-layer materials suitable for photocatalytic water splitting.

Localized states in an arbitrarily bent quantum wire (bend-imitating approach)

NASA Astrophysics Data System (ADS)

Vakhnenko, Oleksity O.

1996-02-01

The bend-imitating matching technique is proposed to simplify the quantum mechanical treatment of singly and multiply bent 2D quantum wires of constant width, arbitrary bending angles, arbitrary bending radii and arbitrary distances between the bends. The spectrum of one-electron localized states and its dependence on the bending angle and the bending radius in a singly bent wire is explicitly calculated. Doubly bent wires are shown to possess doubly split localized states. The splitting energies as a function of the distance between the bends and the bending angles and bending radii have also been obtained. A similar description of bent 3D quantum wires and bent optical fibers is expected to be possible.

Atomic-scale distortion of optically activated Sm dopants identified with site-selective X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Ishii, Masashi; Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce; Hu, Yongfeng; Sham, Tsun-Kong; Harako, Susumu; Zhao, Xin-Wei; Komuro, Shuji

2013-10-01

The local structure of luminescent Sm dopants was investigated using an X-ray absorption fine-structure technique with X-ray-excited optical luminescence. Because this technique evaluates X-ray absorption from luminescence, only optically active sites are analyzed. The Sm L3 near-edge spectrum contains split 5d states and a shake-up transition that are specific to luminescent Sm. Theoretical calculations using cluster models identified an atomic-scale distortion that can reproduce the split 5d states. The model with C4v local symmetry and compressive bond length of Sm-O of a six-fold oxygen (SmO6) cluster is most consistent with the experimental results.

Effects of spin-orbit coupling and many-body correlations in STM transport through copper phthalocyanine.

PubMed

Siegert, Benjamin; Donarini, Andrea; Grifoni, Milena

2015-01-01

The interplay of exchange correlations and spin-orbit interaction (SOI) on the many-body spectrum of a copper phtalocyanine (CuPc) molecule and their signatures in transport are investigated. We first derive a minimal model Hamiltonian in a basis of frontier orbitals that is able to reproduce experimentally observed singlet-triplet splittings. In a second step SOI effects are included perturbatively. Major consequences of the SOI are the splitting of former degenerate levels and a magnetic anisotropy, which can be captured by an effective low-energy spin Hamiltonian. We show that scanning tunneling microscopy-based magnetoconductance measurements can yield clear signatures of both these SOI-induced effects.

Matter distribution and spin-orbit force in spherical nuclei

NASA Astrophysics Data System (ADS)

Co', G.; Anguiano, M.; De Donno, V.; Lallena, A. M.

2018-03-01

We investigate the possibility that some nuclei show density distributions with a depletion in the center, a semibubble structure, by using a Hartree-Fock plus Bardeen-Cooper-Schrieffer approach. We separately study the proton, neutron, and matter distributions in 37 spherical nuclei mainly in the s -d shell region. We found a relation between the semibubble structure and the energy splitting of spin-orbit partner single particle levels. The presence of semibubble structure reduces this splitting, and we study its consequences on the excitation spectrum of the nuclei under investigation by using a quasiparticle random-phase-approximation approach. The excitation energies of the low-lying 4+ states can be related to the presence of semibubble structure in nuclei.

Polarized Fine Structure in the Photoluminescence Excitation Spectrum of a Negatively Charged Quantum Dot

NASA Astrophysics Data System (ADS)

Ware, M. E.; Stinaff, E. A.; Gammon, D.; Doty, M. F.; Bracker, A. S.; Gershoni, D.; Korenev, V. L.; Bădescu, Ş. C.; Lyanda-Geller, Y.; Reinecke, T. L.

2005-10-01

We report polarized photoluminescence excitation spectroscopy of the negative trion in single charge-tunable InAs/GaAs quantum dots. The spectrum exhibits a p-shell resonance with polarized fine structure arising from the direct excitation of the electron spin triplet states. The energy splitting arises from the axially symmetric electron-hole exchange interaction. The magnitude and sign of the polarization are understood from the spin character of the triplet states and a small amount of quantum dot asymmetry, which mixes the wave functions through asymmetric e-e and e-h exchange interactions.

Numerical investigation on splitting of ferrofluid microdroplets in T-junctions using an asymmetric magnetic field with proposed correlation

NASA Astrophysics Data System (ADS)

Aboutalebi, Mohammad; Bijarchi, Mohamad Ali; Shafii, Mohammad Behshad; Kazemzadeh Hannani, Siamak

2018-02-01

The studies surrounding the concept of microdroplets have seen a dramatic increase in recent years. Microdroplets have applications in different fields such as chemical synthesis, biology, separation processes and micro-pumps. This study numerically investigates the effect of different parameters such as Capillary number, Length of droplets, and Magnetic Bond number on the splitting process of ferrofluid microdroplets in symmetric T-junctions using an asymmetric magnetic field. The use of said field that is applied asymmetrically to the T-junction center helps us control the splitting of ferrofluid microdroplets. During the process of numerical simulation, a magnetic field with various strengths from a dipole located at a constant distance from the center of the T-junction was applied. The main advantage of this design is its control over the splitting ratio of daughter droplets and reaching various microdroplet sizes in a T-junction by adjusting the magnetic field strength. The results showed that by increasing the strength of the magnetic field, the possibility of asymmetric splitting of microdroplets increases in a way that for high values of field strength, high splitting ratios can be reached. Also, by using the obtained results at various Magnetic Bond numbers and performing curve fitting, a correlation is derived that can be used to accurately predict the borderline between splitting and non-splitting zones of microdroplets flow in micro T-junctions.

Peculiarities of FeSi phonon spectrum induced by a change of atomic volume

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

Parshin, P. P., E-mail: Parshin-PP@nrcki.ru, E-mail: neupar45@yandex.ru; Chumakov, A. I.; Alekseev, P. A.

2016-12-15

We analyze in detail the results of experimental investigations of the evolution of the thermal vibration spectra for iron atoms in iron monosilicide FeSi depending on two external parameters, viz., temperature T (in the range 46–297 K at pressure P = 0.1 MPa) and pressure P (in the range 0.1 MPa–43 GPa at temperature T = 297 K), obtained by nuclear inelastic scattering of synchrotron radiation. The decrease of the atomic volume is accompanied by a rearrangement of the phonon spectrum, which is manifested, in particular, in the splitting of the low-energy peak in the spectrum and in an increasemore » of the energy for all phonons. The changes of the average energy of the iron atom vibrational spectrum and of the Debye energy with decreasing atomic volume are analyzed. Different versions of FeSi electron spectrum variation, which can be used to explain the observed phonon anomalies, are considered.« less

Influenza Vaccine Manufacturing: Effect of Inactivation, Splitting and Site of Manufacturing. Comparison of Influenza Vaccine Production Processes

PubMed Central

Kon, Theone C.; Onu, Adrian; Berbecila, Laurentiu; Lupulescu, Emilia; Ghiorgisor, Alina; Kersten, Gideon F.; Cui, Yi-Qing; Amorij, Jean-Pierre; Van der Pol, Leo

2016-01-01

The aim of this study was to evaluate the impact of different inactivation and splitting procedures on influenza vaccine product composition, stability and recovery to support transfer of process technology. Four split and two whole inactivated virus (WIV) influenza vaccine bulks were produced and compared with respect to release criteria, stability of the bulk and haemagglutinin recovery. One clarified harvest of influenza H3N2 A/Uruguay virus prepared on 25.000 fertilized eggs was divided equally over six downstream processes. The main unit operation for purification was sucrose gradient zonal ultracentrifugation. The inactivation of the virus was performed with either formaldehyde in phosphate buffer or with beta-propiolactone in citrate buffer. For splitting of the viral products in presence of Tween®, either Triton™ X-100 or di-ethyl-ether was used. Removal of ether was established by centrifugation and evaporation, whereas removal of Triton-X100 was performed by hydrophobic interaction chromatography. All products were sterile filtered and subjected to a 5 months real time stability study. In all processes, major product losses were measured after sterile filtration; with larger losses for split virus than for WIV. The beta-propiolactone inactivation on average resulted in higher recoveries compared to processes using formaldehyde inactivation. Especially ether split formaldehyde product showed low recovery and least stability over a period of five months. PMID:26959983

Femtosecond laser-induced subwavelength ripples formed by asymmetrical grating splitting

NASA Astrophysics Data System (ADS)

Feng, Pin; Jiang, Lan; Li, Xin; Zhang, Kaihu; Shi, Xuesong; Li, Bo; Lu, Yongfeng

2016-05-01

The formation process and mechanism of subwavelength ripples were studied upon irradiation of ZnO by a femtosecond laser (800 nm, 50 fs, 1 kHz). An abnormally asymmetrical grating-splitting phenomenon was discovered. At relatively high laser fluences (F = 0.51-0.63 J/cm2), near-wavelength ripples were split asymmetrically to create subwavelength laser-induced periodic surface structures (LIPSS) with dual gaps (˜230 nm and ˜430 nm) on the primary grooves. At relatively low laser fluences (F = 0.4-0.45 J/cm2), near-wavelength ripples were split symmetrically, leading to the formation of uniform subwavelength structures with a period of ˜340 nm. The splitting phenomena are related to the varying laser beam dose induced by the overlapping during line scanning. The two grating-splitting types further imply that the dominated mechanism for LIPSS formation may be changed under different processing conditions.

Occurrence of a 'bad' split and success of initial mandibular healing: a review of 524 sagittal ramus osteotomies in 262 patients.

PubMed

Posnick, J C; Choi, E; Liu, S

2016-10-01

The purpose of this study was to assess the prevalence of a 'bad' split after sagittal ramus osteotomies (SRO) and report the results of initial mandibular healing. A retrospective cohort study derived from patients treated by a single surgeon at one institution between 2004 and 2013 was performed. An index group consisting of a series of subjects with a spectrum of bimaxillary dentofacial deformities also involving the chin and symptomatic chronic obstructive nasal breathing was identified. The SRO design, bicortical screw fixation technique, and perioperative management were consistent. Outcome variables included the occurrence of a 'bad' split and the success of initial SRO healing. Two hundred sixty-two subjects undergoing 524 SROs met the inclusion criteria. Their average age was 25 years (range 13-63 years) and 134 were female (51%). Simultaneous removal of a third molar was performed during 209 of the SROs (40%). There were no 'bad' splits. All subjects achieved successful bone union, the planned occlusion, and return to a chewing diet and physical activities by 5 weeks after surgery. The presence of a third molar removed during SRO was not associated with an increased frequency of a 'bad' split or delayed mandibular healing. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

En face projection imaging of the human choroidal layers with tracking SLO and swept source OCT angiography methods

NASA Astrophysics Data System (ADS)

Gorczynska, Iwona; Migacz, Justin; Zawadzki, Robert J.; Sudheendran, Narendran; Jian, Yifan; Tiruveedhula, Pavan K.; Roorda, Austin; Werner, John S.

2015-07-01

We tested and compared the capability of multiple optical coherence tomography (OCT) angiography methods: phase variance, amplitude decorrelation and speckle variance, with application of the split spectrum technique, to image the choroiretinal complex of the human eye. To test the possibility of OCT imaging stability improvement we utilized a real-time tracking scanning laser ophthalmoscopy (TSLO) system combined with a swept source OCT setup. In addition, we implemented a post- processing volume averaging method for improved angiographic image quality and reduction of motion artifacts. The OCT system operated at the central wavelength of 1040nm to enable sufficient depth penetration into the choroid. Imaging was performed in the eyes of healthy volunteers and patients diagnosed with age-related macular degeneration.

Measuring the Dispersion Curve of a PMMA-Fibre Optic Cable Using a Dye Laser

ERIC Educational Resources Information Center

Zorba, Serkan; Farah, Constantine; Pant, Ravi

2010-01-01

An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

Stereoregularity of poly (lactic acid) and their model compounds as studied by NMR and quantum chemical calculations

USDA-ARS?s Scientific Manuscript database

In order to understand the origin of the tacticity splitting in the NMR spectrum of poly(lactic acid), monomer model compound and dimer model compounds (both isotactic and syndiotactic) were synthesized and their 1H and 13C NMR chemical shifts observed. Two energetically stable conformations were o...

Solar thermochemical splitting of water to generate hydrogen

PubMed Central

Rao, C. N. R.; Dey, Sunita

2017-01-01

Solar photochemical means of splitting water (artificial photosynthesis) to generate hydrogen is emerging as a viable process. The solar thermochemical route also promises to be an attractive means of achieving this objective. In this paper we present different types of thermochemical cycles that one can use for the purpose. These include the low-temperature multistep process as well as the high-temperature two-step process. It is noteworthy that the multistep process based on the Mn(II)/Mn(III) oxide system can be carried out at 700 °C or 750 °C. The two-step process has been achieved at 1,300 °C/900 °C by using yttrium-based rare earth manganites. It seems possible to render this high-temperature process as an isothermal process. Thermodynamics and kinetics of H2O splitting are largely controlled by the inherent redox properties of the materials. Interestingly, under the conditions of H2O splitting in the high-temperature process CO2 can also be decomposed to CO, providing a feasible method for generating the industrially important syngas (CO+H2). Although carbonate formation can be addressed as a hurdle during CO2 splitting, the problem can be avoided by a suitable choice of experimental conditions. The choice of the solar reactor holds the key for the commercialization of thermochemical fuel production. PMID:28522461

Exciton Absorption in Semiconductor Quantum Wells Driven by a Strong Intersubband Pump Field

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Ning, Cun-Zheng

1999-01-01

Optical interband excitonic absorption of semiconductor quantum wells (QW's) driven by a coherent pump field is investigated based on semiconductor Bloch equations. The pump field has a photon energy close to the intersubband spacing between the first two conduction subbands in the QW's. An external weak optical field probes the interband transition. The excitonic effects and pump-induced population redistribution within the conduction subbands in the QW system are included. When the density of the electron-hole pairs in the QW structure is low, the pump field induces an Autler-Townes splitting of the exciton absorption spectrum. The split size and the peak positions of the absorption doublet depend not only on the pump frequency and intensity but also on the carrier density. As the density of the electron-hole pairs is increased, the split contrast (the ratio between the maximum and minimum values) is decreased because the exciton effect is suppressed at higher densities due to the many-body screening.

From the tunneling dimer to the onset of microsolvation: Infrared spectroscopy of allyl radical water aggregates in helium nanodroplets

NASA Astrophysics Data System (ADS)

Leicht, Daniel; Kaufmann, Matin; Pal, Nitish; Schwaab, Gerhard; Havenith, Martina

2017-03-01

The infrared spectrum of allyl:water clusters embedded in helium nanodroplets was recorded. Allyl radicals were produced by flash vacuum pyrolysis and trapped in helium droplets. Deuterated water was added to the doped droplets, and the infrared spectrum of the radical water aggregates was recorded in the frequency range 2570-2820 cm-1. Several absorption bands are observed and assigned to 1:1 and 1:2 allyl:D2O clusters, based on pressure dependent measurements and accompanying quantum chemical calculations. The analysis of the 1:1 cluster spectrum revealed a tunneling splitting as well as a combination band. For the 1:2 cluster, we observe a water dimer-like motif that is bound by one π-hydrogen bond to the allyl radical.

Multiplet Splitting Effects on Core-Level Photoemission and Inverse-Photoemission Spectra of Uranium Intermetallic Compounds

NASA Astrophysics Data System (ADS)

Okada, Kozo

1999-03-01

The present paper discusses the role of U 5f-5f exchange interaction (J) in the inverse photoemission spectrum (IPES) and the U 4f x-ray photoemission spectrum (XPS) of uranium intermetallic compounds. The origin of the broad main peak in the IPES of UPd3 and UPd2Al3, for instance, is ascribed to the exchange coupling effects of 5f electrons. In other words, whether the ground state is of high-spin or of low-spin is directly reflected in the width of the IPES. On the other hand, the interpretation for the U 4f photoemission spectrum is not so greatly influenced by J. The full-multiplet calculations are also performed for an U4+ ion for comparison.

Distinct Retinal Capillary Plexuses in Normal Eyes as Observed in Optical Coherence Tomography Angiography Axial Profile Analysis.

PubMed

Hirano, Takao; Chanwimol, Karntida; Weichsel, Julian; Tepelus, Tudor; Sadda, Srinivas

2018-06-20

Optical coherence tomography angiography (OCTA) allows the retinal microvasculature to be visualized at various retinal depths. Previous studies introduced OCTA axial profile analysis and showed regional variations in the number and location of axially distinct vascular retinal plexuses. OCTA acquisition and processing approaches, however, vary in terms of their resulting transverse and axial resolutions, and especially the latter could potentially influence the profile analysis results. Our study imaged normal eyes using the Spectralis OCT2 with a full-spectrum, probabilistic OCTA algorithm, that, in marked contrast to split-spectrum approaches, preserves the original high OCT axial resolution also within the resulting OCTA signal. En face OCTA images are generally created by averaging flow signals over a finite axial depth window. However, we assessed regional OCTA signal profiles at each depth position at full axial resolution. All regions had two sharp vessel density peaks near the inner and outer boundaries of the inner nuclear layer, indicating separate intermediate and deep capillary plexuses. The superficial vascular plexus (SVP) separated into two distinct peaks within the ganglion cell layer in the parafoveal zone. The nasal, superior, and inferior perifovea had a deeper SVP peak that was shifted anteriorly compared to the parafoveal zone. Axial vascular density analysis with high-resolution, full spectrum OCTA thus allows healthy retinal vasculature to be precisely reconstructed and may be useful for clinically assessing retinal pathology.

Effect of Processing on the in Vitro and in Vivo Protein Quality of Yellow and Green Split Peas (Pisum sativum).

PubMed

Nosworthy, Matthew G; Franczyk, Adam J; Medina, Gerardo; Neufeld, Jason; Appah, Paulyn; Utioh, Alphonsus; Frohlich, Peter; House, James D

2017-09-06

In order to determine the effect of extrusion, baking, and cooking on the protein quality of yellow and green split peas, a rodent bioassay was conducted and compared to an in vitro method of protein quality determination. The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) of green split peas (71.4%) was higher than that of yellow split peas (67.8%), on average. Similarly, the average Digestible Indispensable Amino Acid Score (DIAAS) of green split peas (69%) was higher than that of yellow split peas (67%). Cooked green pea flour had lower PDCAAS and DIAAS values (69.19% and 67%) than either extruded (73.61%, 70%) or baked (75.22%, 70%). Conversely, cooked yellow split peas had the highest PDCCAS value (69.19%), while extruded yellow split peas had the highest DIAAS value (67%). Interestingly, a strong correlation was found between in vivo and in vitro analysis of protein quality (R 2 = 0.9745). This work highlights the differences between processing methods on pea protein quality and suggests that in vitro measurements of protein digestibility could be used as a surrogate for in vivo analysis.

Spectral splitting of optical pulses inside a dispersive medium at a temporal boundary

DOE PAGES

Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

2016-11-07

We show numerically that the spectrum of an optical pulse splits into multiple, widely separated, spectral bands when it arrives at a temporal boundary across which refractive index changes suddenly. At the same time, the pulse breaks into several temporally separated pulses traveling at different speeds. The number of such pulses depends on the dispersive properties of the medium. We study the effect of second- and third-order dispersion in detail but also consider briefly the impact of other higher-order terms. As a result, a temporal waveguide formed with two temporal boundaries can reflect the temporally separated pulses again and again,more » increasing the number of pulses trapped within the temporal waveguide.« less

Line shape analysis of the K β transition in muonic hydrogen

NASA Astrophysics Data System (ADS)

Covita, Daniel S.; Anagnostopoulos, Dimitrios F.; Fuhrmann, Hermann; Gorke, Hubert; Gotta, Detlev; Gruber, Alexander; Hirtl, Albert; Ishiwatari, Tomoichi; Indelicato, Paul; Jensen, Thomas S.; Le Bigot, Eric-Olivier; Markushin, Valeri E.; Nekipelov, Michael; Pomerantsev, Vladimir N.; Popov, Vladimir P.; dos Santos, Joaquim M. F.; Schmid, Philipp; Simons, Leopold M.; Theisen, Marian; Trassinelli, Martino; Veloso, Joao F. C. A.; Zmeskal, Johann

2018-04-01

The K β transition in muonic hydrogen was measured with a high-resolution crystal spectrometer. The spectrum is shown to be sensitive to the ground-state hyperfine splitting, the corresponding triplet-to-singlet ratio, and the kinetic energy distribution in the 3 p state. The hyperfine splitting and triplet-to-singlet ratio are found to be consistent with the values expected from theoretical and experimental investigations and, therefore, were fixed accordingly in order to reduce the uncertainties in the further reconstruction of the kinetic energy distribution. The presence of high-energetic components was established and quantified in both a phenomenological, i.e. cascade-model-free fit, and in a direct deconvolution of the Doppler broadening based on the Bayesian method.

Microtia Combined With Split Sole of Feet, Deformed Middle Fingers and Café -au-lait Spots on the Trunk: A New Association.

PubMed

Yu, Yan; Hu, Jintian; Liu, Tun; Cao, Yilin; Zhang, Qingguo

2015-11-01

Microtia is a spectrum of congenital deformities. Approximately, half of the patients are associated with hemifacial microtia. The birth rate of microtia ranges from 2 per 10,000 to 17.4 per 10,000. Microtia and limb deformities sometimes occurred simultaneously as described in the literature. In this report, the patient was found to be with unilateral microtia combined with bilateral split sole of feet, deformed middle fingers on both hands, and café-au-lait spots on the trunk. Despite a thorough literature search, the authors could not achieve a satisfactory diagnosis for the current case with respect to the type of anomalies seen in the case.

Rotational spectrum of 14N 2 · H 35Cl and 14N 2 · H 37Cl: electric field gradients at the nitrogen nuclei

NASA Astrophysics Data System (ADS)

Kisiel, Z.; Pszczólkowski, L.; Fowler, P. W.; Legon, A. C.

1997-09-01

Rotational spectra of the most abundant isotopic species of the weakly bound dimer formed between dinitrogen and hydrogen chloride were investigated. Spectroscopic constants for 14N 2 · H 37Cl were determined for the first time and those for 14N 2 · H 35Cl improved. Analysis of observed nuclear quadrupole spliting patterns within the framework of coupling of three nonequivalent nuclear spins allowed determination of splitting constants for both nuclei in the complexed dinitrogen molecule. Electric field gradient calculations at the SCF supermolecule level for the dimer are presented and account for the observed values of the nitrogen splitting constants.

Unveiling the photonic spin Hall effect of freely propagating fan-shaped cylindrical vector vortex beams.

PubMed

Zhang, Yi; Li, Peng; Liu, Sheng; Zhao, Jianlin

2015-10-01

An intriguing photonic spin Hall effect (SHE) for a freely propagating fan-shaped cylindrical vector (CV) vortex beam in a paraxial situation is theoretically and experimentally studied. A developed model to describe this kind of photonic SHE is proposed based on angular spectrum diffraction theory. With this model, the close dependences of spin-dependent splitting on the azimuthal order of polarization, the topological charge of the spiral phase, and the propagation distance are accurately revealed. Furthermore, it is demonstrated that the asymmetric spin-dependent splitting of a fan-shaped CV beam can be consciously managed, even with a constant azimuthal order of polarization. Such a controllable photonic SHE is experimentally verified by measuring the Stokes parameters.

Ca 3d unoccupied states in Bi2Sr2CaCu2O8 investigated by Ca L2,3 x-ray-absorption near-edge structure

NASA Astrophysics Data System (ADS)

Borg, A.; King, P. L.; Pianetta, P.; Lindau, I.; Mitzi, D. B.; Kapitulnik, A.; Soldatov, A. V.; della Longa, S.; Bianconi, A.

1992-10-01

The high-resolution Ca L2,3 x-ray-absorption near-edge-structure (XANES) spectrum of a Bi2Sr2CaCu2O8 single crystal has been measured by use of a magnetic-projection x-ray microscope probing a surface area of 200×200 μm2. The Ca L2,3 XANES spectrum is analyzed by performing a multiple-scattering XANES calculation in real space and comparing the results with the spectrum of CaF2. Good agreement between the calculated and experimental crystal-field splitting Δf of the Ca 3d final states is found and the splitting is shown to be smaller by 0.5 eV than in the initial state. The Ca 3d partial density of states is found to be close to the Fermi level in the initial state. The Ca-O(in plane) distance is shown to be a critical parameter associated with the shift of the Ca 3d states relative to the Fermi level; in particular, we have studied the effect of the out-of-plane dimpling mode of the in-plane oxygen atoms O(in plane) that will move the Ca 3d states on or off the Fermi level. This mode can therefore play a role in modulating the charge transfer between the two CuO2 planes separated by the Ca ions.

Characteristics of the gait adaptation process due to split-belt treadmill walking under a wide range of right-left speed ratios in humans.

PubMed

Yokoyama, Hikaru; Sato, Koji; Ogawa, Tetsuya; Yamamoto, Shin-Ichiro; Nakazawa, Kimitaka; Kawashima, Noritaka

2018-01-01

The adaptability of human bipedal locomotion has been studied using split-belt treadmill walking. Most of previous studies utilized experimental protocol under remarkably different split ratios (e.g. 1:2, 1:3, or 1:4). While, there is limited research with regard to adaptive process under the small speed ratios. It is important to know the nature of adaptive process under ratio smaller than 1:2, because systematic evaluation of the gait adaptation under small to moderate split ratios would enable us to examine relative contribution of two forms of adaptation (reactive feedback and predictive feedforward control) on gait adaptation. We therefore examined a gait behavior due to on split-belt treadmill adaptation under five belt speed difference conditions (from 1:1.2 to 1:2). Gait parameters related to reactive control (stance time) showed quick adjustments immediately after imposing the split-belt walking in all five speed ratios. Meanwhile, parameters related to predictive control (step length and anterior force) showed a clear pattern of adaptation and subsequent aftereffects except for the 1:1.2 adaptation. Additionally, the 1:1.2 ratio was distinguished from other ratios by cluster analysis based on the relationship between the size of adaptation and the aftereffect. Our findings indicate that the reactive feedback control was involved in all the speed ratios tested and that the extent of reaction was proportionally dependent on the speed ratio of the split-belt. On the contrary, predictive feedforward control was necessary when the ratio of the split-belt was greater. These results enable us to consider how a given split-belt training condition would affect the relative contribution of the two strategies on gait adaptation, which must be considered when developing rehabilitation interventions for stroke patients.

StackSplit - a plugin for multi-event shear wave splitting analyses in SplitLab

NASA Astrophysics Data System (ADS)

Grund, Michael

2017-04-01

The SplitLab package (Wüstefeld et al., Computers and Geosciences, 2008), written in MATLAB, is a powerful and widely used tool for analysing seismological shear wave splitting of single event measurements. However, in many cases, especially temporary station deployments close to seaside or for recordings affected by strong anthropogenic noise, only multi-event approaches provide stable and reliable splitting results. In order to extend the original SplitLab environment for such analyses, I present the StackSplit plugin that can easily be implemented within the well accepted main program. StackSplit grants easy access to several different analysis approaches within SplitLab, including a new multiple waveform based inversion method as well as the most established standard stacking procedures. The possibility to switch between different analysis approaches at any time allows the user for the most flexible processing of individual multi-event splitting measurements for a single recording station. Besides the provided functions of the plugin, no other external program is needed for the multi-event analyses since StackSplit performs within the available SplitLab structure.

Midlatitude sporadic-E episodes viewed by L-band split-spectrum InSAR

NASA Astrophysics Data System (ADS)

Furuya, Masato; Suzuki, Takato; Maeda, Jun; Heki, Kosuke

2017-12-01

Sporadic-E (Es) is a layer of ionization that irregularly appears within the E region of the ionosphere and is known to generate an unusual propagation of very high frequency waves over long distances. The detailed spatial structure of Es remains unclear due to the limited spatial resolution in the conventional ionosonde observations. We detect midlatitude Es by interferometric synthetic aperture radar (InSAR), which can clarify the spatial structure of Es with unprecedented resolution. Moreover, we use the range split-spectrum method (SSM) to separate dispersive and nondispersive components in the InSAR image. While InSAR SSM largely succeeds in decomposing into dispersive and nondispersive signals, our results indicate that small-scale dispersive signals due to the total electron content anomalies are accompanied by nondispersive signals with similar spatial scale at the same locations. We also examine the effects of higher-order terms in the refractive index for dispersive media. Both of these detected Es episodes indicate that smaller-scale dispersive effects originate from higher-order effects. We interpret that the smaller-scale nondispersive signals could indicate the emergence of nitric oxide (NO) generated by the reactions of metals, Mg and Fe, with nitric oxide ion (NO+) during the Es.

Fourier transformation microwave spectroscopy of the methyl glycolate-H2O complex

NASA Astrophysics Data System (ADS)

Fujitake, Masaharu; Tanaka, Toshihiro; Ohashi, Nobukimi

2018-01-01

The rotational spectrum of one conformer of the methyl glycolate-H2O complex has been measured by means of the pulsed jet Fourier transform microwave spectrometer. The observed a- and b-type transitions exhibit doublet splittings due to the internal rotation of the methyl group. On the other hand, most of the c-type transitions exhibit quartet splittings arising from the methyl internal rotation and the inversion motion between two equivalent conformations. The spectrum was analyzed using parameterized expressions of the Hamiltonian matrix elements derived by applying the tunneling matrix formalism. Based on the results obtained from ab initio calculation, the observed complex of methyl glycolate-H2O was assigned to the most stable conformer of the insertion complex, in which a non-planer seven membered-ring structure is formed by the intermolecular hydrogen bonds between methyl glycolate and H2O subunits. The inversion motion observed in the c-type transitions is therefore a kind of ring-inversion motion between two equivalent conformations. Conformational flexibility, which corresponds to the ring-inversion between two equivalent conformations and to the isomerization between two possible conformers of the insertion complex, was investigated with the help of the ab initio calculation.

Free-form Fresnel RXI Köhler design with spectrum-splitting for photovoltaics

NASA Astrophysics Data System (ADS)

Buljan, M.; Benítez, P.; Mohedano, R.; Miñano, J. C.; Sun, Y.; Falicoff, W.; Vilaplana, J.; Chaves, J.; Biot, G.; López, J.

2011-10-01

Here we present a novel optical design of the high concentration photovoltaics (HPCV) nonimaging concentrator (>500x) with built-in spectrum splitting concept. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded in it, both POE and SOE performing Köhler integration to produce light homogenization on the target. It uses the combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-Point-Contact (BPC) silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell's reflection. Design targets equivalent cell efficiency ~46% using commercial 39% 3J and 26% Si cells, and CPV module efficiency greater than 38%, achieved at a concentration level larger than 500X and wide acceptance angle (+/-1°). A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ~100x and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J with peak efficiency of 36.9%.

Fee Splitting among General Practitioners: A Cross-Sectional Study in Iran.

PubMed

Parsa, Mojtaba; Larijani, Bagher; Aramesh, Kiarash; Nedjat, Saharnaz; Fotouhi, Akbar; Yekaninejad, Mir Saeed; Ebrahimian, Nejatollah; Kandi, Mohamad Jafar

2016-12-01

Fee splitting is a process whereby a physician refers a patient to another physician or a healthcare facility and receives a portion of the charge in return. This survey was conducted to study general practitioners' (GPs) attitudes toward fee splitting as well as the prevalence, causes, and consequences of this process. This is a cross-sectional study on 223 general practitioners in 2013. Concerning the causes and consequences of fee splitting, an unpublished qualitative study was conducted by interviewing a number of GPs and specialists and the questionnaire options were the results of the information obtained from this study. Of the total 320 GPs, 247 returned the questionnaires. The response rate was 77.18%. Of the 247 returned questionnaires, 223 fulfilled the inclusion criteria. Among the participants, 69.1% considered fee splitting completely wrong and 23.2% (frequently or rarely) practiced fee splitting. The present study showed that the prevalence of fee splitting among physicians who had positive attitudes toward fee splitting was 4.63 times higher than those who had negative attitudes. In addition, this study showed that, compared to private hospitals, fee splitting is less practiced in public hospitals. The major cause of fee splitting was found to be unrealistic/unfair tariffs and the main consequence of fee splitting was thought to be an increase in the number of unnecessary patient referrals. Fee splitting is an unethical act, contradicts the goals of the medical profession, and undermines patient's best interest. In Iran, there is no code of ethics on fee splitting, but in this study, it was found that the majority of GPs considered it unethical. However, among those who had negative attitudes toward fee splitting, there were physicians who did practice fee splitting. The results of the study showed that physicians who had a positive attitude toward fee splitting practiced it more than others. Therefore, if physicians consider fee splitting unethical, its rate will certainly decrease. The study claims that to decrease such practice, the healthcare system has to revise the tariffs.

Coupled-resonator waveguide perfect transport single-photon by interatomic dipole-dipole interaction

NASA Astrophysics Data System (ADS)

Yan, Guo-an; Lu, Hua; Qiao, Hao-xue; Chen, Ai-xi; Wu, Wan-qing

2018-06-01

We theoretically investigate single-photon coherent transport in a one-dimensional coupled-resonator waveguide coupled to two quantum emitters with dipole-dipole interactions. The numerical simulations demonstrate that the transmission spectrum of the photon depends on the two atoms dipole-dipole interactions and the photon-atom couplings. The dipole-dipole interactions may change the dip positions in the spectra and the coupling strength may broaden the frequency band width in the transmission spectrum. We further demonstrate that the typical transmission spectra split into two dips due to the dipole-dipole interactions. This phenomenon may be used to manufacture new quantum waveguide devices.

Perovskite nanocomposites as effective CO2-splitting agents in a cyclic redox scheme

PubMed Central

Zhang, Junshe; Haribal, Vasudev; Li, Fanxing

2017-01-01

We report iron-containing mixed-oxide nanocomposites as highly effective redox materials for thermochemical CO2 splitting and methane partial oxidation in a cyclic redox scheme, where methane was introduced as an oxygen “sink” to promote the reduction of the redox materials followed by reoxidation through CO2 splitting. Up to 96% syngas selectivity in the methane partial oxidation step and close to complete conversion of CO2 to CO in the CO2-splitting step were achieved at 900° to 980°C with good redox stability. The productivity and production rate of CO in the CO2-splitting step were about seven times higher than those in state-of-the-art solar-thermal CO2-splitting processes, which are carried out at significantly higher temperatures. The proposed approach can potentially be applied for acetic acid synthesis with up to 84% reduction in CO2 emission when compared to state-of-the-art processes. PMID:28875171

Travelling and splitting of a wave of hedgehog expression involved in spider-head segmentation.

PubMed

Kanayama, Masaki; Akiyama-Oda, Yasuko; Nishimura, Osamu; Tarui, Hiroshi; Agata, Kiyokazu; Oda, Hiroki

2011-10-11

During development segmentation is a process that generates a spatial periodic pattern. Peak splitting of waves of gene expression is a mathematically predicted, simple strategy accounting for this type of process, but it has not been well characterized biologically. Here we show temporally repeated splitting of gene expression into stripes that is associated with head axis growth in the spider Achaearanea embryo. Preceding segmentation, a wave of hedgehog homologue gene expression is observed to travel posteriorly during development stage 6. This stripe, co-expressing an orthodenticle homologue, undergoes two cycles of splitting and shifting accompanied by convergent extension, serving as a generative zone for the head segments. The two orthodenticle and odd-paired homologues are identified as targets of Hedgehog signalling, and evidence suggests that their activities mediate feedback to maintain the head generative zone and to promote stripe splitting in this zone. We propose that the 'stripe-splitting' strategy employs genetic components shared with Drosophila blastoderm subdivision, which are required for participation in an autoregulatory signalling network.

Real-Time Fault Classification for Plasma Processes

PubMed Central

Yang, Ryan; Chen, Rongshun

2011-01-01

Plasma process tools, which usually cost several millions of US dollars, are often used in the semiconductor fabrication etching process. If the plasma process is halted due to some process fault, the productivity will be reduced and the cost will increase. In order to maximize the product/wafer yield and tool productivity, a timely and effective fault process detection is required in a plasma reactor. The classification of fault events can help the users to quickly identify fault processes, and thus can save downtime of the plasma tool. In this work, optical emission spectroscopy (OES) is employed as the metrology sensor for in-situ process monitoring. Splitting into twelve different match rates by spectrum bands, the matching rate indicator in our previous work (Yang, R.; Chen, R.S. Sensors 2010, 10, 5703–5723) is used to detect the fault process. Based on the match data, a real-time classification of plasma faults is achieved by a novel method, developed in this study. Experiments were conducted to validate the novel fault classification. From the experimental results, we may conclude that the proposed method is feasible inasmuch that the overall accuracy rate of the classification for fault event shifts is 27 out of 28 or about 96.4% in success. PMID:22164001

Eavesdropping on spin waves inside the domain-wall nanochannel via three-magnon processes

NASA Astrophysics Data System (ADS)

Zhang, Beining; Wang, Zhenyu; Cao, Yunshan; Yan, Peng; Wang, X. R.

2018-03-01

One recent breakthrough in the field of magnonics is the experimental realization of reconfigurable spin-wave nanochannels formed by a magnetic domain wall with a width of 10-100 nm [Wagner et al., Nat. Nano. 11, 432 (2016), 10.1038/nnano.2015.339]. This remarkable progress enables an energy-efficient spin-wave propagation with a well-defined wave vector along its propagating path inside the wall. In the mentioned experiment, a microfocus Brillouin light scattering spectroscopy was taken in a line-scans manner to measure the frequency of the bounded spin wave. Due to their localization nature, the confined spin waves can hardly be detected from outside the wall channel, which guarantees the information security to some extent. In this work, we theoretically propose a scheme to detect/eavesdrop on the spin waves inside the domain-wall nanochannel via nonlinear three-magnon processes. We send a spin wave (ωi,ki) in one magnetic domain to interact with the bounded mode (ωb,kb) in the wall, where kb is parallel with the domain-wall channel defined as the z ̂ axis. Two kinds of three-magnon processes, i.e., confluence and splitting, are expected to occur. The confluence process is conventional: conservation of energy and momentum parallel with the wall indicates a transmitted wave in the opposite domain with ω (k ) =ωi+ωb and (ki+kb-k ) .z ̂=0 , while the momentum perpendicular to the domain wall is not necessary to be conserved due to the nonuniform internal field near the wall. We predict a stimulated three-magnon splitting (or "magnon laser") effect: the presence of a bound magnon propagating along the domain wall channel assists the splitting of the incident wave into two modes, one is ω1=ωb,k1=kb identical to the bound mode in the channel, and the other one is ω2=ωi-ωb with (ki-kb-k2) .z ̂=0 propagating in the opposite magnetic domain. Micromagnetic simulations confirm our theoretical analysis. These results demonstrate that one is able to uniquely infer the spectrum of the spin wave in the domain-wall nanochannel once we know both the injection and the transmitted waves.

Performance Models for Split-execution Computing Systems

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

Humble, Travis S; McCaskey, Alex; Schrock, Jonathan

Split-execution computing leverages the capabilities of multiple computational models to solve problems, but splitting program execution across different computational models incurs costs associated with the translation between domains. We analyze the performance of a split-execution computing system developed from conventional and quantum processing units (QPUs) by using behavioral models that track resource usage. We focus on asymmetric processing models built using conventional CPUs and a family of special-purpose QPUs that employ quantum computing principles. Our performance models account for the translation of a classical optimization problem into the physical representation required by the quantum processor while also accounting for hardwaremore » limitations and conventional processor speed and memory. We conclude that the bottleneck in this split-execution computing system lies at the quantum-classical interface and that the primary time cost is independent of quantum processor behavior.« less

Duplication of the pituitary gland associated with multiple blastogenesis defects: Duplication of the pituitary gland (DPG)-plus syndrome. Case report and review of literature.

PubMed

Manjila, Sunil; Miller, Erin A; Vadera, Sumeet; Goel, Rishi K; Khan, Fahd R; Crowe, Carol; Geertman, Robert T

2012-01-01

Duplication of the pituitary gland (DPG) is a rare craniofacial developmental anomaly occurring during blastogenesis with postulated etiology such as incomplete twinning, teratogens, median cleft face syndrome or splitting of the notochord. The complex craniocaudal spectrum of blastogenesis defects associated with DPG is examined with an illustrative case. We report for the first time in the medical literature some unique associations with DPG, such as a clival encephalocele, third cerebral peduncle, duplicate odontoid process and a double tongue with independent volitional control. This patient also has the previously reported common associations such as duplicated sella, cleft palate, hypertelorism, callosal agenesis, hypothalamic enlargement, nasopharyngeal teratoma, fenestrated basilar artery and supernumerary teeth. This study also reviews 37 cases of DPG identified through MEDLINE literature search from 1880 to 2011. It provides a detailed analysis of the current case through physical examination and imaging. The authors propose that the developmental deformities associated with duplication of pituitary gland (DPG) occur as part of a developmental continuum, not as chance associations. Considering the fact that DPG is uniquely and certainly present throughout the spectrum of these blastogenesis defects, we suggest the term DPG-plus syndrome.

First principles studies on the redox ability of (Ga(1-x)Zn(x))N(1-x)O(x) solid solutions and thermal reactions for H2 and O2 production on their surfaces.

PubMed

Du, Yaojun A; Chen, Yun-Wen; Kuo, Jer-Lai

2013-12-07

The (Ga1-xZnx)N1-xOx solid solution has been emerging as an effective photocatalyst for water splitting utilizing the visible solar spectrum, regarded as a host GaN bulk doped with ZnO impurities. H2 and O2 production occur simultaneously and stoichiometrically on the surface of (Ga1-xZnx)N1-xOx particles. In this work, we characterize the redox ability of (Ga1-xZnx)N1-xOx and find that a solid solution with a ZnO concentration of 0.125 < x < 0.250 is optimal for water splitting. This is consistent with the experimental finding that the maximum photocatalytic activity of (Ga1-xZnx)N1-xOx is achieved at x = 0.13. The thermal reactions of water splitting are modeled on both the GaN and an idealized (Ga1-xZnx)N1-xOx (101[combining macron]0) surface. The computed activation barriers allow us to gain some clues on the efficiency of water splitting on a specific photocatalyst surface. Our results suggest that the non-polar (101[combining macron]0) and polar (0001) surfaces may play different roles in water splitting, i.e., the (101[combining macron]0) surface is responsible for O2 production, while hydroxyl groups could dissociate on the (0001) surface.

Analysis and modeling of wafer-level process variability in 28 nm FD-SOI using split C-V measurements

NASA Astrophysics Data System (ADS)

Pradeep, Krishna; Poiroux, Thierry; Scheer, Patrick; Juge, André; Gouget, Gilles; Ghibaudo, Gérard

2018-07-01

This work details the analysis of wafer level global process variability in 28 nm FD-SOI using split C-V measurements. The proposed approach initially evaluates the native on wafer process variability using efficient extraction methods on split C-V measurements. The on-wafer threshold voltage (VT) variability is first studied and modeled using a simple analytical model. Then, a statistical model based on the Leti-UTSOI compact model is proposed to describe the total C-V variability in different bias conditions. This statistical model is finally used to study the contribution of each process parameter to the total C-V variability.

Absence of a dose-fractionation effect on neoplastic transformation induced by fission-spectrum neutrons in C3H 10T1/2 cells

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

Saran, A.; Pazzaglia, S.; Coppola, M.

1991-06-01

We have investigated the effect of fission-spectrum neutron dose fractionation on neoplastic transformation of exponentially growing C3H 10T1/2 cells. Total doses of 10.8, 27, 54, and 108 cGy were given in single doses or in five equal fractions delivered at 24-h intervals in the biological channel of the RSV-TAPIRO reactor at CRE-Casaccia. Both cell inactivation and neoplastic transformation were more effectively induced by fission neutrons than by 250-kVp X rays. No significant effect on cell survival or neoplastic transformation was observed with split doses compared to single doses of fission-spectrum neutrons. Neutron RBE values relative to X rays determined frommore » data for survival and neoplastic transformation were comparable.« less

The far-infrared laser magnetic resonance spectrum of the SiH radical and determination of ground state parameters

NASA Technical Reports Server (NTRS)

Brown, J. M.; Curl, R. F.; Evenson, K. M.

1984-01-01

The far-infrared laser magnetic resonance spectrum of the SiH radical in the v = O level of its X2Pi state has been recorded. The signals are rather weak. The molecules were generated in the reaction between fluorine atoms and SiH4. Rotational transitions have been detected in both 2Pi1/2 and 2Pi3/2 spin components but no fine structure transitions between the spin components were observed. Proton hyperfine splittings were resolved on some lines. The measurements have been analyzed, subjected to a least-squares fit using an effective Hamiltonian, and the appropriate molecular parameters determined. The weakness of the spectrum and the failure of attempts to power saturate favorable lines are both consistent with a small value for the electric dipole moment for SiH.

Post-Impact Fatigue Damage Monitoring Using Fiber Bragg Grating Sensors

PubMed Central

Shin, Chow-Shing; Liaw, Shien-Kuei; Yang, Shi-Wei

2014-01-01

It has been shown that impact damage to composite materials can be revealed by embedded Fiber Bragg Gratings (FBG) as a broadening and splitting of the latter's characteristic narrow peak reflected spectrum. The current work further subjected the impact damaged composite to cyclic loading and found that the FBG spectrum gradually submerged into a rise of background intensity as internal damages progressed. By skipping the impact, directing the impact to positions away from the FBG and examining the extracted fibers, we concluded that the above change is not a result of deterioration/damage of the sensor. It is caused solely by the damages initiated in the composite by the impact and aggravated by fatigue loading. Evolution of the grating spectrum may therefore be used to monitor qualitatively the development of the incurred damages. PMID:24594609

Spin interactions in InAs quantum dots

NASA Astrophysics Data System (ADS)

Doty, M. F.; Ware, M. E.; Stinaff, E. A.; Scheibner, M.; Bracker, A. S.; Gammon, D.; Ponomarev, I. V.; Reinecke, T. L.; Korenev, V. L.

2006-03-01

Fine structure splittings in optical spectra of self-assembled InAs quantum dots (QDs) generally arise from spin interactions between particles confined in the dots. We present experimental studies of the fine structure that arises from multiple charges confined in a single dot [1] or in molecular orbitals of coupled pairs of dots. To probe the underlying spin interactions we inject particles with a known spin orientation (by using polarized light to perform photoluminescence excitation spectroscopy experiments) or use a magnetic field to orient and/or mix the spin states. We develop a model of the spin interactions that aids in the development of quantum information processing applications based on controllable interactions between spins confined to QDs. [1] Polarized Fine Structure in the Photoluminescence Excitation Spectrum of a Negatively Charged Quantum Dot, Phys. Rev. Lett. 95, 177403 (2005)

Tunneling dynamics of double proton transfer in formic acid and benzoic acid dimers

NASA Astrophysics Data System (ADS)

Smedarchina, Zorka; Fernández-Ramos, Antonio; Siebrand, Willem

2005-04-01

Direct dynamics calculations based on instanton techniques are reported of tunneling splittings due to double proton transfer in formic and benzoic acid dimers. The results are used to assign the observed splittings to levels for which the authors of the high-resolution spectra could not provide a definitive assignment. In both cases the splitting is shown to be due mainly to the zero-point level rather than to the vibrationally or electronically excited level whose spectrum was investigated. This leads to zero-point splittings of 375MHz for (DCOOH)2 and 1107MHz for the benzoic acid dimer. Thus, contrary to earlier calculations, it is found that the splitting is considerably larger in the benzoic than in the formic acid dimer. The calculations are extended to solid benzoic acid where the asymmetry of the proton-transfer potential induced by the crystal can be overcome by suitable doping. This has allowed direct measurement of the interactions responsible for double proton transfer, which were found to be much larger than those in the isolated dimer. To account for this observation both static and dynamic effects of the crystal forces on the intradimer hydrogen bonds are included in the calculations. The same methodology, extended to higher temperatures, is used to calculate rate constants for HH, HD, and DD transfers in neat benzoic acid crystals. The results are in good agreement with reported experimental rate constants measured by NMR relaxometry and, if allowance is made for small structural changes induced by doping, with the transfer matrix elements observed in doped crystals. Hence the method used allows a unified description of tunneling splittings in the gas phase and in doped crystals as well as of transfer rates in neat crystals.

Influence of the large-small split effect on strategy choice in complex subtraction.

PubMed

Xiang, Yan Hui; Wu, Hao; Shang, Rui Hong; Chao, Xiaomei; Ren, Ting Ting; Zheng, Li Ling; Mo, Lei

2018-04-01

Two main theories have been used to explain the arithmetic split effect: decision-making process theory and strategy choice theory. Using the inequality paradigm, previous studies have confirmed that individuals tend to adopt a plausibility-checking strategy and a whole-calculation strategy to solve large and small split problems in complex addition arithmetic, respectively. This supports strategy choice theory, but it is unknown whether this theory also explains performance in solving different split problems in complex subtraction arithmetic. This study used small, intermediate and large split sizes, with each split condition being further divided into problems requiring and not requiring borrowing. The reaction times (RTs) for large and intermediate splits were significantly shorter than those for small splits, while accuracy was significantly higher for large and middle splits than for small splits, reflecting no speed-accuracy trade-off. Further, RTs and accuracy differed significantly between the borrow and no-borrow conditions only for small splits. This study indicates that strategy choice theory is suitable to explain the split effect in complex subtraction arithmetic. That is, individuals tend to choose the plausibility-checking strategy or the whole-calculation strategy according to the split size. © 2016 International Union of Psychological Science.

StackSplit - a plugin for multi-event shear wave splitting analyses in SplitLab

NASA Astrophysics Data System (ADS)

Grund, Michael

2017-08-01

SplitLab is a powerful and widely used tool for analysing seismological shear wave splitting of single event measurements. However, in many cases, especially temporary station deployments close to the noisy seaside, ocean bottom or for recordings affected by strong anthropogenic noise, only multi-event approaches provide stable and reliable splitting results. In order to extend the original SplitLab environment for such analyses, I present the StackSplit plugin that can easily be implemented within the well accepted main program. StackSplit grants easy access to several different analysis approaches within SplitLab, including a new multiple waveform based inversion method as well as the most established standard stacking procedures. The possibility to switch between different analysis approaches at any time allows the user for the most flexible processing of individual multi-event splitting measurements for a single recording station. Besides the provided functions of the plugin, no other external program is needed for the multi-event analyses since StackSplit performs within the available SplitLab structure which is based on MATLAB. The effectiveness and use of this plugin is demonstrated with data examples of a long running seismological recording station in Finland.

Tablet splitting of a narrow therapeutic index drug: a case with levothyroxine sodium.

PubMed

Shah, Rakhi B; Collier, Jarrod S; Sayeed, Vilayat A; Bryant, Arthur; Habib, Muhammad J; Khan, Mansoor A

2010-09-01

Levothyroxine is a narrow therapeutic index, and to avoid adverse effect associated with under or excessive dosage, the dose response is carefully titrated. The tablets are marketed with a score providing an option to split. However, there are no systematic studies evaluating the effect of splitting on dose accuracy, and current study was undertaken to evaluate effects of splitting and potential causes for uniformity failures by measuring assay and content uniformity in whole and split tablets. Stability was evaluated by assaying drug for a period of 8 weeks. Effect of formulation factors on splittability was evaluated by a systematic investigation of formulation factors by preparing levothyroxine tablets in house by varying the type of excipients (binder, diluent, disintegrant, glidant) or by varying the processing factors (granulating liquid, mixing type, compression pressure). The tablets were analyzed using novel analytical tool such as near infrared chemical imaging to visualize the distribution of levothyroxine. Assay was not significantly different for whole versus split tablets irrespective of method of splitting (hand or splitter), and splitting also had no measurable impact on the stability. Split tablets either by hand or splitter showed higher rate of content uniformity failures as compared to whole tablets. Tablet splitter produced more fragmentation and, hence, more content uniformity and friability failures. Chemical imaging data revealed that the distribution of levothyroxine was heterogeneous and was dependent on type of binder and the process used in the manufacture of tablets. Splitting such tablets could prove detrimental if sub- or super-potency becomes an issue.

Transforming White Light into Rainbows: Segmentation Strategies for Successful School Tax Elections

ERIC Educational Resources Information Center

Senden, J. Bradford; Lifto, Don E.

2009-01-01

In the late 1600s, British physicist Sir Isaac Newton first demonstrated refraction and dispersion in a triangular prism. He discovered that a prism could decompose white light into a spectrum. Hold a prism up to the light at the correct angle and white light magically splits into vivid colors of the rainbow! So what do prisms and rainbows have to…

Initial Test Bed for Very High Efficiency Solar Cells

DTIC Science & Technology

2008-05-01

efficiency, both at the solar cell and module levels. The optical system consists of a tiled nonimaging concentrating system, coupled with a spectral...Benítez, P. (2005). Nonimaging Optics . Boston: Elsevier Academic Press. [6] Luque, A.L. & Andreev, V.M. (2007). Concentrator Photovoltaics. New York: Springer. ...lateral optical concentrating system, which splits the incident solar spectrum into several bands and allows different optical and photovoltaic

Electronic spectrum of non-tetrahedral acceptors in CdTe:Cl and CdTe:Bi,Cl single crystals

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

Krivobok, V. S., E-mail: krivobok@lebedev.ru; Moscow Institute of Physics and Technology; Nikolaev, S. N.

2016-02-07

The electronic spectra of complex acceptors in compensated CdTe:Cl, CdTe:Ag,Cl, and CdTe:Bi,Cl single crystals are studied using low-temperature photoluminescence (PL) measurements under both nonresonant and resonant excitation of distant donor–acceptor pairs (DAP). The wavelength modulation of the excitation source combined with the analysis of the differential PL signal is used to enhance narrow spectral features obscured because of inhomogeneous line broadening and/or excitation transfer for selectively excited DAPs. For the well-known tetrahedral (T{sub D}) Ag{sub Cd} acceptor, the energies of four excited states are measured, and the values obtained are shown to be in perfect agreement with the previous data.more » Moreover, splitting between the 2P{sub 3/2} (Γ{sub 8}) and 2S{sub 3/2} (Γ{sub 8}) states is clearly observed for Ag{sub Cd} centers located at a short distance (5–7 nm) from a hydrogen-like donor (Cl{sub Te}). This splitting results from the reduction of the T{sub D} symmetry taking place when the acceptor is a member of a donor–acceptor pair. For the Cl-related complex acceptor with an activation energy of ∼121 meV (A-center), the energies of eight excited states are measured. It is shown that this defect produces low-symmetry central-cell correction responsible for the strong splitting of S-like T{sub D} shells. The energy spectrum of the Bi-related shallow acceptor with an activation energy of ∼36 meV is measured as well. The spectrum obtained differs drastically from the hydrogen-like set of levels, which indicates the existence of repulsive low-symmetry perturbation of the hydrogen-like Coulomb potential. It is also shown that the spectra of selectively excited PL recorded for a macroscopic ensemble of distant donor–acceptor pairs allow one to detect the low symmetry of acceptors of a given type caused by their complex nature or by the Jahn–Teller distortion. This method does not require any additional (external) field and is applicable to acceptors in diverse zinc-blende compound semiconductors.« less

Resolving the Magnetic Asymmetry of the Inner Space in Self-assembled Dimeric Capsules Based on Tetraurea-calix[4]pyrrole Components.

PubMed

Espelt, Mónica; Aragay, Gemma; Ballester, Pablo

2015-01-01

The encapsulation of N,N, N',N'-tetramethyl-1,5-pentanediamine-N,N'-dioxide 2 in a non-chiral capsular assembly formed by dimerization of tetraurea-calix[4]pyrrole 1a produced the observation of the N-methyl groups of the encapsulated guest as two separated singlets resonating highly upfield in the (1)H NMR spectrum. In order to clarify the origin of the observed signal splitting we assembled and studied a series of structurally related dimeric capsules. We used the tetraurea-calix[4]pyrrole 1a , the enantiomerically pure tetraurea-calix[4] pyrrole R-1b and the tetraurea-bisloop calix[4]pyrrole 1c as components of the produced assemblies. The (1)H NMR spectra of the assembled encapsulation complexes with bis-N-oxide 2 evidenced diverse splitting patterns of the N-methyl groups. In addition, 2D EXSY/ROESY NMR experiments revealed the existence of chemical exchange processes involving the separated methyl signals of the encapsulated guest. The capsular assemblies were mainly stabilized by a belt of eight head-to-tail hydrogen-bonded urea groups. The interconversion between the two senses of rotation of the unidirectionally oriented urea groups was slow on the (1)H NMR timescale. These characteristics determined the appearance of a new asymmetry element (supramolecular conformational chirality) in the assemblies that accounted for some of the magnetic asymmetries featured by the capsule's inner space. The racemization of the supramolecular chirality element was fast on the EXSY timescale and produced the chemical exchange processes detected for the encapsulation complexes.

Activation of response force by self-splitting objects: where are the limits of feedforward Gestalt processing?

PubMed

Schmidt, Filipp; Weber, Andreas; Schmidt, Thomas

2014-08-21

Most objects can be recognized easily even when they are partly occluded. This also holds when several overlapping objects share the same surface features (self-splitting objects) which is an illustration of the grouping principle of Good Gestalt. We employed outline and filled contour stimuli in a primed flanker task to test whether the processing of self-splitting objects is in accordance with a simple feedforward model. We obtained priming effects in response time and response force for both types of stimuli, even when increasing the number of occluders up to three. The results for outline contours were in full accordance with a feedforward account. This was not the case for the results for filled contours (i.e., for self-splitting objects), especially under conditions of strong occlusion. We conclude that the implementation of the Good Gestalt principle is fast but still based on recurrent processing. © 2014 ARVO.

Using Symmetry Group Correlation Tables to Explain why Erham (and Other Programs) cannot BE Used to Analyze Torsional Splittings of Some Molecules

NASA Astrophysics Data System (ADS)

Groner, Peter

2016-06-01

ERHAM has been used to analyze rotational spectra of many molecules with torsional splitting caused by one or two internal rotors. The gauche form of dimethyl ether-d1 whose equilibrium structure has C1 symmetry is an example of a molecule for which ERHAM could not model additional small splittings resolvable for many transitions, whereas the spectrum of the symmetric (anti, trans) form with a C{_s} equilibrium structure could be analyzed successfully with ERHAM. A more recent example where ERHAM failed is pinacolone CH_3-CO-C(CH_3)_3. In this case, the barriers to internal rotation of the methyl groups within the -C(CH_3)_3 unit are too high to produce observable internal rotation splittings, but the splittings due to the CH_3-CO methyl group could not be modeled correctly with ERHAM nor with any other available program (XIAM, BELGI-Cs, BELGI-C1, RAM36). In the paper, it was speculated that BELGI-Cs-2tops might be able to the job, but arguments against this possibility have also been put forward. The correlation between irreducible representations of groups and their subgroups according to Watson can be used not only to determine the total number of substates (components) to be expected but also to help decide which particular program has a chance for a successful analysis. As it turns out, the number of components of split lines depends on the molecular symmetry at equilibrium in relation to the highest possible symmetry for a given molecular symmetry group. Therefore, for pinacolone, the vibrational ground state is split into 10 torsional substates. P. Groner, J. Mol. Spectrosc. 278 (2012) 52-67. C. Richard et al. A&A 552 (2013), A117. Y. Zhao et al., J. Mol. Spectrosc. 318 (2015) 91-100, with references to all other programs mentioned in the abstract. J. K. G. Watson, Can. J. Physics 43 (1965) 1996-2007.

Measuring 20-100 T B-fields using Zeeman splitting of sodium emission lines on a 500 kA pulsed power machine

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

Banasek, J. T., E-mail: jtb254@cornell.edu; Engelbrecht, J. T.; Pikuz, S. A.

2016-11-15

We have shown that Zeeman splitting of the sodium (Na) D-lines at 5890 and 5896 Å can be used to measure the magnetic field (B-field) produced in high current pulsed power experiments. We have measured the B-field next to a return current conductor in a hybrid X-pinch experiment near a peak current of about 500 kA. Na is deposited on the conductor and then is desorbed and excited by radiation from the hybrid X-pinch. The D-line emission spectrum implies B-fields of about 20 T with a return current post of 4 mm diameter or up to 120 T with amore » return current wire of 0.455 mm diameter. These measurements were consistent or lower than the expected B-field, thereby showing that basic Zeeman splitting can be used to measure the B-field in a pulsed-power-driven high-energy-density (HED) plasma experiment. We hope to extend these measurement techniques using suitable ionized species to measurements within HED plasmas.« less

Analysis of mobile fronthaul bandwidth and wireless transmission performance in split-PHY processing architecture.

PubMed

Miyamoto, Kenji; Kuwano, Shigeru; Terada, Jun; Otaka, Akihiro

2016-01-25

We analyze the mobile fronthaul (MFH) bandwidth and the wireless transmission performance in the split-PHY processing (SPP) architecture, which redefines the functional split of centralized/cloud RAN (C-RAN) while preserving high wireless coordinated multi-point (CoMP) transmission/reception performance. The SPP architecture splits the base stations (BS) functions between wireless channel coding/decoding and wireless modulation/demodulation, and employs its own CoMP joint transmission and reception schemes. Simulation results show that the SPP architecture reduces the MFH bandwidth by up to 97% from conventional C-RAN while matching the wireless bit error rate (BER) performance of conventional C-RAN in uplink joint reception with only 2-dB signal to noise ratio (SNR) penalty.

A Split-Attention Effect in Multimedia Learning: Evidence for Dual Processing Systems in Working Memory.

ERIC Educational Resources Information Center

Mayer, Richard E.; Moreno, Roxana

1998-01-01

Multimedia learners (n=146 college students) were able to integrate words and computer-presented pictures more easily when the words were presented aurally rather than visually. This split-attention effect is consistent with a dual-processing model of working memory. (SLD)

Characteristics of the gait adaptation process due to split-belt treadmill walking under a wide range of right-left speed ratios in humans

PubMed Central

Ogawa, Tetsuya; Yamamoto, Shin-Ichiro; Nakazawa, Kimitaka

2018-01-01

The adaptability of human bipedal locomotion has been studied using split-belt treadmill walking. Most of previous studies utilized experimental protocol under remarkably different split ratios (e.g. 1:2, 1:3, or 1:4). While, there is limited research with regard to adaptive process under the small speed ratios. It is important to know the nature of adaptive process under ratio smaller than 1:2, because systematic evaluation of the gait adaptation under small to moderate split ratios would enable us to examine relative contribution of two forms of adaptation (reactive feedback and predictive feedforward control) on gait adaptation. We therefore examined a gait behavior due to on split-belt treadmill adaptation under five belt speed difference conditions (from 1:1.2 to 1:2). Gait parameters related to reactive control (stance time) showed quick adjustments immediately after imposing the split-belt walking in all five speed ratios. Meanwhile, parameters related to predictive control (step length and anterior force) showed a clear pattern of adaptation and subsequent aftereffects except for the 1:1.2 adaptation. Additionally, the 1:1.2 ratio was distinguished from other ratios by cluster analysis based on the relationship between the size of adaptation and the aftereffect. Our findings indicate that the reactive feedback control was involved in all the speed ratios tested and that the extent of reaction was proportionally dependent on the speed ratio of the split-belt. On the contrary, predictive feedforward control was necessary when the ratio of the split-belt was greater. These results enable us to consider how a given split-belt training condition would affect the relative contribution of the two strategies on gait adaptation, which must be considered when developing rehabilitation interventions for stroke patients. PMID:29694404

Spectroscopy of collective excitations in interacting low-dimensional many-body systems using quench dynamics.

PubMed

Gritsev, Vladimir; Demler, Eugene; Lukin, Mikhail; Polkovnikov, Anatoli

2007-11-16

We study the problem of rapid change of the interaction parameter (quench) in a many-body low-dimensional system. It is shown that, measuring the correlation functions after the quench, the information about a spectrum of collective excitations in a system can be obtained. This observation is supported by analysis of several integrable models and we argue that it is valid for nonintegrable models as well. Our conclusions are supplemented by performing exact numerical simulations on finite systems. We propose that measuring the power spectrum in a dynamically split 1D Bose-Einsten condensate into two coupled condensates can be used as an experimental test of our predictions.

Broadband multiple responses of surface modes in quasicrystalline plasmonic structure

PubMed Central

Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

2016-01-01

We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum. PMID:27492782

Plasmons in N-doped graphene nanostructures tuned by Au/Ag films: a time-dependent density functional theory study.

PubMed

Shu, Xiaoqin; Cheng, Xinlu; Zhang, Hong

2018-04-18

The energy resonance point of the prominent peak of the absorption spectrum of nitrogen-doped graphene is in the ultraviolet region. This limits its application as a co-catalyst in renewable hydrogen evolution through photocatalytic water splitting in the visible light region. It is well known that noble metal films show active absorption in the visible region due to the existence of the unique feature known as surface plasmon resonance. Here we report tunable plasmons in nitrogen-doped graphene nanostructures using noble metal (Au/Ag) films. The energy resonance point of the prominent peak of the composite nanostructure is altered by changing the separation space of two-layered nanostructures. We found the strength of the absorption spectrum of the composite nanostructure is much stronger than the isolated N-doped graphene monolayer. When the separation space is decreased, the prominent peak of the absorption spectrum is red-shifted to the visible light region. Moreover, currents of several microamperes exist above the surface of the N-doped graphene and Au film composite nanostructure. In addition, the field enhancement exceeds 1000 when an impulse excitation polarized in the armchair-edge direction (X-axis) when the separation space is decreased to 3 Å and is close to 100 when an impulse excitation polarized in the zigzag-edge direction (Y-axis). The N-doped graphene and noble metal film composite nanostructure is a good candidate material as a co-catalyst in renewable hydrogen production by photocatalytic water splitting in the visible light region.

Tuning the electrical and optical anisotropy of a monolayer black phosphorus magnetic superlattice

NASA Astrophysics Data System (ADS)

Li, X. J.; Yu, J. H.; Luo, K.; Wu, Z. H.; Yang, W.

2018-04-01

We investigate theoretically the effects of modulated periodic perpendicular magnetic fields on the electronic states and optical absorption spectrum in monolayer black phosphorus (phosphorene). We demonstrate that different phosphorene magnetic superlattice (PMS) orientations can give rise to distinct energy spectra, i.e. tuning the intrinsic electronic anisotropy. Rashba spin-orbit coupling (RSOC) develops a spin-splitting energy dispersion in this phosphorene magnetic superlattice. Anisotropic momentum-dependent carrier distributions along/perpendicular to the magnetic strips are demonstrated. The manipulations of these exotic electronic properties by tuning superlattice geometry, magnetic field and the RSOC term are addressed systematically. Accordingly, we find bright-to-dark transitions in the ground-state electron-hole pair transition rate spectrum and the PMS orientation-dependent anisotropic optical absorption spectrum. This feature offers us a practical way of modulating the electronic anisotropy in phosphorene by magnetic superlattice configurations and detecting this modulation capability by using an optical technique.

Full-spectrum volumetric solar thermal conversion via photonic nanofluids.

PubMed

Liu, Xianglei; Xuan, Yimin

2017-10-12

Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i.e., Janus nanoparticles. The solar thermal conversion efficiency can be improved by 10.8% compared with core-shell nanofluids. The extinction coefficient of Janus dimers with various configurations is also investigated to unveil the effects of particle couplings. This work provides the possibility to achieve full-spectrum volumetric solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

Lyman-α forest constraints on decaying dark matter

NASA Astrophysics Data System (ADS)

Wang, Mei-Yu; Croft, Rupert A. C.; Peter, Annika H. G.; Zentner, Andrew R.; Purcell, Chris W.

2013-12-01

We present an analysis of high-resolution N-body simulations of decaying dark matter cosmologies focusing on the statistical properties of the transmitted Lyman-α (Lyα) forest flux in the high-redshift intergalactic medium (IGM). In this type of model a dark matter particle decays into a slightly less massive stable dark matter daughter particle and a comparably light particle. The small mass splitting provides a nonrelativistic kick velocity Vk=cΔM/M to the daughter particle resulting in free-streaming and subsequent damping of small-scale density fluctuations. Current Lyα forest power spectrum measurements probe comoving scales up to ˜2-3h-1Mpc at redshifts z˜2-4, providing one of the most robust ways to probe cosmological density fluctuations on relatively small scales. The suppression of structure growth due to the free-streaming of dark matter daughter particles also has a significant impact on the neutral hydrogen cloud distribution, which traces the underlying dark matter distribution well at high redshift. We exploit Lyα forest power spectrum measurements to constrain the amount of free-streaming of dark matter in such models and thereby place limits on decaying dark matter based only on the dynamics of cosmological perturbations without any assumptions about the interactions of the decay products. We use a suite of dark-matter-only simulations together with the fluctuating Gunn-Peterson approximation to derive the Lyα flux distribution. We argue that this approach should be sufficient for our main purpose, which is to demonstrate the power of the Lyα forest to constrain decaying dark matter models. We find that Sloan Digital Sky Survey 1D Lyα forest power spectrum data place a lifetime-dependent upper limit Vk≲30-70km/s for decay lifetimes ≲10Gyr. This is the most stringent model-independent bound on invisible dark matter decays with small mass splittings. For larger mass splittings (large Vk), Lyα forest data restrict the dark matter lifetime to Γ-1≳40Gyr. We leave the calibration of IGM properties using high-resolution hydrodynamic simulations for future work, which might become necessary if we consider data with higher precision such as the Baryon Oscillation and Spectroscopic Survey (BOSS) Lyα data. Forthcoming BOSS data should be able to provide more stringent constraints on exotic dark matter, mainly because the larger BOSS quasar spectrum sample will significantly reduce statistical errors.

The GA sulfur-iodine water-splitting process - A status report

NASA Astrophysics Data System (ADS)

Besenbruch, G. E.; Chiger, H. D.; McCorkle, K. H.; Norman, J. H.; Rode, J. S.; Schuster, J. R.; Trester, P. W.

The development of a sulfur-iodine thermal water splitting cycle is described. The process features a 50% thermal efficiency, plus all liquid and gas handling. Basic chemical investigations comprised the development of multitemperature and multistage sulfuric acid boost reactors, defining the phase behavior of the HI/I2/H2O/H3PO4 mixtures, and development of a decomposition process for hydrogen iodide in the liquid phase. Initial process engineering studies have led to a 47% efficiency, improvements of 2% projected, followed by coupling high-temperature solar concentrators to the splitting processes to reduce power requirements. Conceptual flowsheets developed from bench models are provided; materials investigations have concentrated on candidates which can withstand corrosive mixtures at temperatures up to 400 deg K, with Hastelloy C-276 exhibiting the best properties for containment and heat exchange to I2.

The GA sulfur-iodine water-splitting process - A status report

NASA Technical Reports Server (NTRS)

Besenbruch, G. E.; Chiger, H. D.; Mccorkle, K. H.; Norman, J. H.; Rode, J. S.; Schuster, J. R.; Trester, P. W.

1981-01-01

The development of a sulfur-iodine thermal water splitting cycle is described. The process features a 50% thermal efficiency, plus all liquid and gas handling. Basic chemical investigations comprised the development of multitemperature and multistage sulfuric acid boost reactors, defining the phase behavior of the HI/I2/H2O/H3PO4 mixtures, and development of a decomposition process for hydrogen iodide in the liquid phase. Initial process engineering studies have led to a 47% efficiency, improvements of 2% projected, followed by coupling high-temperature solar concentrators to the splitting processes to reduce power requirements. Conceptual flowsheets developed from bench models are provided; materials investigations have concentrated on candidates which can withstand corrosive mixtures at temperatures up to 400 deg K, with Hastelloy C-276 exhibiting the best properties for containment and heat exchange to I2.

Attosecond twin-pulse control by generalized kinetic heterodyne mixing.

PubMed

Raith, Philipp; Ott, Christian; Pfeifer, Thomas

2011-01-15

Attosecond double-pulse (twin-pulse) production in high-order harmonic generation is manipulated by a combination of two-color and carrier-envelope phase-control methods. As we show in numerical simulations, both relative amplitude and phase of the double pulse can be independently set by making use of multidimensional parameter control. Two technical implementation routes are discussed: kinetic heterodyning using second-harmonic generation and split-spectrum phase-step control.

Investigation of the multiplet features of SrTiO 3 in X-ray absorption spectra based on configuration interaction calculations

DOE PAGES

Wu, M.; Xin, Houlin L.; Wang, J. O.; ...

2018-04-24

Synchrotron-based L 2,3-edge absorption spectra show strong sensitivities to the local electronic structure and chemical environment. However, detailed physical information cannot be extracted easily without computational aids. Here in this study using the experimental Ti L 2,3-edges absorption spectrum of SrTiO 3as a fingerprint and considering full multiplet effects, calculations yield different energy parameters characterizing local ground state properties. The peak splitting and intensity ratios of the L 3 and L 2 set of peaks are carefully analyzed quantitatively, giving rise to a small hybridization energy around 1.2 eV, and the different hybridization energy values reported in the literature aremore » further addressed. Finally, absorption spectra with different linearly polarized photons under various tetragonal crystal fields are investigated, revealing a non-linear orbital–lattice interaction, and a theoretical guidance for material engineering of SrTiO 3-based thin films and heterostructures is offered. Finally, detailed analysis of spectrum shifts with different tetragonal crystal fields suggests that the e g crystal field splitting is a necessary parameter for a thorough analysis of the spectra, even though it is not relevant for the ground state properties.« less

Investigation of the multiplet features of SrTiO 3 in X-ray absorption spectra based on configuration interaction calculations

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

Wu, M.; Xin, Houlin L.; Wang, J. O.

Synchrotron-based L 2,3-edge absorption spectra show strong sensitivities to the local electronic structure and chemical environment. However, detailed physical information cannot be extracted easily without computational aids. Here in this study using the experimental Ti L 2,3-edges absorption spectrum of SrTiO 3as a fingerprint and considering full multiplet effects, calculations yield different energy parameters characterizing local ground state properties. The peak splitting and intensity ratios of the L 3 and L 2 set of peaks are carefully analyzed quantitatively, giving rise to a small hybridization energy around 1.2 eV, and the different hybridization energy values reported in the literature aremore » further addressed. Finally, absorption spectra with different linearly polarized photons under various tetragonal crystal fields are investigated, revealing a non-linear orbital–lattice interaction, and a theoretical guidance for material engineering of SrTiO 3-based thin films and heterostructures is offered. Finally, detailed analysis of spectrum shifts with different tetragonal crystal fields suggests that the e g crystal field splitting is a necessary parameter for a thorough analysis of the spectra, even though it is not relevant for the ground state properties.« less

CO2 in solid para-hydrogen: spectral splitting and the CO2···(o-H2)n clusters.

PubMed

Du, Jun-He; Wan, Lei; Wu, Lei; Xu, Gang; Deng, Wen-Ping; Liu, An-Wen; Chen, Yang; Hu, Shui-Ming

2011-02-17

Complicated high-resolution spectral structures are often observed for molecules doped in solid molecular hydrogen. The structures can result from miscellaneous effects and are often interpreted differently in references. The spectrum of the ν(3) band of CO(2) in solid para-H(2) presents a model system which exhibits rich spectral structures. With the help of the potential energy simulation of the CO(2) molecule doped in para-hydrogen matrix, and extensive experiments with different CO(2) isotopologues and different ortho-hydrogen concentrations in the matrix, the spectral features observed in p-H(2) matrix are assigned to the CO(2)···(o-H(2))(n) clusters and also to energy level splitting that is due to different alignments of the doped CO(2) molecules in the matrix. The assignments are further supported by the dynamics analysis and also by the spectrum recorded with sample codoped with O(2) which serves as catalyst transferring o-H(2) to p-H(2) in the matrix at 4 K temperature. The observed spectral features of CO(2)/pH(2) can potentially be used as an alternative readout of the temperature and orthohydrogen concentration in the solid para-hydrogen.

Charge Splitting In Situ Recorder (CSIR) for Real-Time Examination of Plasma Charging Effect in FinFET BEOL Processes

NASA Astrophysics Data System (ADS)

Tsai, Yi-Pei; Hsieh, Ting-Huan; Lin, Chrong Jung; King, Ya-Chin

2017-09-01

A novel device for monitoring plasma-induced damage in the back-end-of-line (BEOL) process with charge splitting capability is first-time proposed and demonstrated. This novel charge splitting in situ recorder (CSIR) can independently trace the amount and polarity of plasma charging effects during the manufacturing process of advanced fin field-effect transistor (FinFET) circuits. Not only does it reveal the real-time and in situ plasma charging levels on the antennas, but it also separates positive and negative charging effect and provides two independent readings. As CMOS technologies push for finer metal lines in the future, the new charge separation scheme provides a powerful tool for BEOL process optimization and further device reliability improvements.

Eye-fixation behavior, lexical storage, and visual word recognition in a split processing model.

PubMed

Shillcock, R; Ellison, T M; Monaghan, P

2000-10-01

Some of the implications of a model of visual word recognition in which processing is conditioned by the anatomical splitting of the visual field between the two hemispheres of the brain are explored. The authors investigate the optimal processing of visually presented words within such an architecture, and, for a realistically sized lexicon of English, characterize a computationally optimal fixation point in reading. They demonstrate that this approach motivates a range of behavior observed in reading isolated words and text, including the optimal viewing position and its relationship with the preferred viewing location, the failure to fixate smaller words, asymmetries in hemisphere-specific processing, and the priority given to the exterior letters of words. The authors also show that split architectures facilitate the uptake of all the letter-position information necessary for efficient word recognition and that this information may be less specific than is normally assumed. A split model of word recognition captures a range of behavior in reading that is greater than that covered by existing models of visual word recognition.

Towards ultrafast dynamics with split-pulse X-ray photon correlation spectroscopy at free electron laser sources

DOE PAGES

Roseker, W.; Hruszkewycz, S. O.; Lehmkuhler, F.; ...

2018-04-27

One of the important challenges in condensed matter science is to understand ultrafast, atomic-scale fluctuations that dictate dynamic processes in equilibrium and non-equilibrium materials. Here, we report an important step towards reaching that goal by using a state-of-the-art perfect crystal based split-and-delay system, capable of splitting individual X-ray pulses and introducing femtosecond to nanosecond time delays. We show the results of an ultrafast hard X-ray photon correlation spectroscopy experiment at LCLS where split X-ray pulses were used to measure the dynamics of gold nanoparticles suspended in hexane. We show how reliable speckle contrast values can be extracted even from verymore » low intensity free electron laser (FEL) speckle patterns by applying maximum likelihood fitting, thus demonstrating the potential of a split-and-delay approach for dynamics measurements at FEL sources. This will enable the characterization of equilibrium and, importantly also reversible non-equilibrium processes in atomically disordered materials.« less

Towards ultrafast dynamics with split-pulse X-ray photon correlation spectroscopy at free electron laser sources

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

Roseker, W.; Hruszkewycz, S. O.; Lehmkuhler, F.

One of the important challenges in condensed matter science is to understand ultrafast, atomic-scale fluctuations that dictate dynamic processes in equilibrium and non-equilibrium materials. Here, we report an important step towards reaching that goal by using a state-of-the-art perfect crystal based split-and-delay system, capable of splitting individual X-ray pulses and introducing femtosecond to nanosecond time delays. We show the results of an ultrafast hard X-ray photon correlation spectroscopy experiment at LCLS where split X-ray pulses were used to measure the dynamics of gold nanoparticles suspended in hexane. We show how reliable speckle contrast values can be extracted even from verymore » low intensity free electron laser (FEL) speckle patterns by applying maximum likelihood fitting, thus demonstrating the potential of a split-and-delay approach for dynamics measurements at FEL sources. This will enable the characterization of equilibrium and, importantly also reversible non-equilibrium processes in atomically disordered materials.« less

Physical preparation and optical properties of CuSbS2 nanocrystals by mechanical alloying process

NASA Astrophysics Data System (ADS)

Zhang, Huihui; Xu, Qishu; Tan, Guolong

2016-09-01

CuSbS2 nanocrystals have been synthesized through mechanical alloying Cu, Sb and S elemental powders for 40 hs. The optical spectrum of as-milled CuSbS2 nano-powders demonstrates a direct gap of 1.35 eV and an indirect gap of 0.36 eV, which are similar to that of silicon and reveals the evidence for the indirect semiconductor characterization of CuSbS2. Afterwards, CuSbS2 nanocrystals were capped with trioctylphosphine oxide/trioctylphosphine/pyridine (TOPO/TOP). There appear four sharp absorption peaks within the region of 315 to 355 nm for the dispersion solution containing the capped nanocrystals. The multiple peaks are proposed to be originating from the energy level splitting of 1S electronic state into four discrete sub-levels, where electrons were excited into the conduction band and thus four exciton absorption peaks were produced.

Superconducting Solenoid for Superfast THz Spectroscopy

NASA Astrophysics Data System (ADS)

Bragin, A. V.; Khrushchev, S. V.; Kubarev, V. V.; Mezencev, N. A.; Tsukanov, V. M.; Sozinov, G. I.; Shkaruba, V. A.

This project is related to new spectroscopy method in little-developed THz range. The method is founded on using of a free electron laser (NovoFEL) with high spectral power radiation which can be smoothly tuned in desirable range of spectrum. The objects of research of this method are fast processes in physics, chemical and biological reactions. Uniform magnetic field of 6 T value in the research area can considerably increase possibilities of this method. The magnetic field will modulate radiation of free molecules induction on characteristic frequencies of the Zeeman splitting that gives more possibilities of identification of molecules having even weak magnetic momentum. Moreover, the use of magnetic field allows essentially increase sensitivity of this method due to almost complete separation of weak measuring signals from powerful radiation of the laser. A superconducting solenoid was developed for this method. Its design and peculiarities are described in this paper.

Three dimensional chiral plasmon rulers based on silver nanorod trimers.

PubMed

Han, Chunrui; Yang, Lechen; Ye, Piao; Parrott, Edward P J; Pickwell-Macpherson, Emma; Tam, Wing Yim

2018-04-16

The symmetry dependences of plasmon excitation modes are studied in 3D silver nanorod trimers. The degenerate plasmon modes split into chiral modes by breaking the inversion and mirror symmetry of the nanorod trimer through translation and/or rotation of the middle rod. With a translation operation, successive evolution of the circular dichroism (CD) spectrum can be achieved through gradual breaking of the inversion symmetry. An additional rotation operation produces even dramatic spectral changes due to breaking a quasi-mirror symmetry resulted from the same angular distance of the middle rod to the top and bottom rods. Especially, pairs of new chiral modes can be excited due to the contact of the middle rod with the top-bottom rod pair. The spectral changes in the simulations, which are also demonstrated experimentally, envision the 3D chiral nanorod trimer system as plasmon ruler for spatial configuration retrieval and dynamic bio-process analysis at the single molecule level.

Airy pulse shaping using time-dependent power-law potentials

NASA Astrophysics Data System (ADS)

Han, Tianwen; Chen, Hao; Qin, Chengzhi; Li, Wenwan; Wang, Bing; Lu, Peixiang

2018-06-01

We investigate the temporal and spectral evolutions of finite-energy Airy pulses in the presence of power-law optical potentials. The potentials are generated by the time-dependent pumped light, which propagates together with the Airy pulses in a highly nonlinear optical fiber. We show that the intrinsic acceleration of Airy pulses can be modified by an external force that stems from a linear potential, and hence unidirectional frequency shift can be realized. When a triangle potential is employed, the pulse will exhibit self-splitting both in temporal and spectral domains. Additionally, as a parabolic potential is utilized, both the temporal waveform and frequency spectrum of the Airy pulse will exchange alternately between the Airy and Gaussian profiles. By using higher-order power-law potentials, we also realize both revival and antirevival effects for the Airy pulses. The study may find wide applications in pulse reshaping and spectral-temporal imaging for both optical communication and signal processing.

Multi-octave supercontinuum generation from mid-infrared filamentation in a bulk crystal

PubMed Central

Silva, F.; Austin, D.R.; Thai, A.; Baudisch, M.; Hemmer, M.; Faccio, D.; Couairon, A.; Biegert, J.

2012-01-01

In supercontinuum generation, various propagation effects combine to produce a dramatic spectral broadening of intense ultrashort optical pulses. With a host of applications, supercontinuum sources are often required to possess a range of properties such as spectral coverage from the ultraviolet across the visible and into the infrared, shot-to-shot repeatability, high spectral energy density and an absence of complicated pulse splitting. Here we present an all-in-one solution, the first supercontinuum in a bulk homogeneous material extending from 450 nm into the mid-infrared. The spectrum spans 3.3 octaves and carries high spectral energy density (2 pJ nm−1–10 nJ nm−1), and the generation process has high shot-to-shot reproducibility and preserves the carrier-to-envelope phase. Our method, based on filamentation of femtosecond mid-infrared pulses in the anomalous dispersion regime, allows for compact new supercontinuum sources. PMID:22549836

Effect of relativity on the ionization spectra of the xenon fluorides XeFn (n=2, 4, 6).

PubMed

Pernpointner, Markus; Cederbaum, Lorenz S

2005-06-01

Noble gas compounds exhibit special chemical bonding situations and have been investigated by various spectroscopic and theoretical techniques. In this work we calculate the ionization spectra of the xenon fluorides (XeF2,XeF4, and XeF6) in the valence and subvalence (down to Xe 4d) areas by application of the recently developed Dirac-Hartree-Fock one-particle propagator technique. In this technique, the relativistic (four-component) and electron correlation effects are computed simultaneously. The xenon compounds show considerable spin-orbit splitting strongly influencing the photoelectron spectrum not reproducible in prior calculations. Comparison to one-component methods is made and the occurring satellite structures are interpreted. The satellite structures can be attributed either to the breakdown of the one-particle picture or to a reflection of intra-atomic and interatomic Auger decay processes within the molecule.

Electronic and Optical Properties of a Semiconducting Spinel (Fe 2 CrO 4 )

DOE PAGES

Chambers, Scott A.; Droubay, Timothy C.; Kaspar, Tiffany C.; ...

2017-01-13

Epitaxial chromium ferrite (Fe 2CrO 4), prepared by state-of-the-art oxygen plasma assisted molecular beam epitaxy, is shown to exhibit unusual electronic transport properties driven by the crystallographic structure and composition of the material. By replacing 1/3 of the Fe cations with Cr converts the host ferrimagnet from a metal into a semiconductor by virtue of its fixed valence (3+); Cr substitutes for Fe at B sites in the spinel lattice. Conversely, replacing 2/3 of the Fe cations with Cr results in an insulator. Three candidate conductive paths, all involving electron hopping between Fe 2+ and Fe 3+, are identified inmore » Fe 2CrO 4. Moreover, Fe 2CrO 4 is shown to be photoconductive across the visible portion of the electromagnetic spectrum. As a result, this material is of potential interest for important photo-electrochemical processes such as water splitting.« less

Colored ultrathin hybrid photovoltaics with high quantum efficiency

DOE PAGES

Lee, Kyu -Tae; Lee, Jae Yong; Seo, Sungyong; ...

2014-10-24

Most current solar panels are fabricated via complex processes using expensive semiconductor materials, and they are rigid and heavy with a dull, black appearance. As a result of their non-aesthetic appearance and weight, they are primarily installed on rooftops to minimize their negative impact on building appearance. The large surfaces and interiors of modern buildings are not efficiently utilized for potential electric power generation. Here, we introduce dual-function solar cells based on ultrathin dopant-free amorphous silicon embedded in an optical cavity that not only efficiently extract the photogenerated carriers but also display distinctive colors with the desired angle-insensitive appearances. Light-energy-harvestingmore » colored signage is demonstrated. Furthermore, a cascaded photovoltaics scheme based on tunable spectrum splitting can be employed to increase power efficiency by absorbing a broader band of light energy. Furthermore, this study pioneers a new approach to architecturally compatible and decorative thin-film photovoltaics.« less

Colored ultrathin hybrid photovoltaics with high quantum efficiency

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

Lee, Kyu -Tae; Lee, Jae Yong; Seo, Sungyong

Most current solar panels are fabricated via complex processes using expensive semiconductor materials, and they are rigid and heavy with a dull, black appearance. As a result of their non-aesthetic appearance and weight, they are primarily installed on rooftops to minimize their negative impact on building appearance. The large surfaces and interiors of modern buildings are not efficiently utilized for potential electric power generation. Here, we introduce dual-function solar cells based on ultrathin dopant-free amorphous silicon embedded in an optical cavity that not only efficiently extract the photogenerated carriers but also display distinctive colors with the desired angle-insensitive appearances. Light-energy-harvestingmore » colored signage is demonstrated. Furthermore, a cascaded photovoltaics scheme based on tunable spectrum splitting can be employed to increase power efficiency by absorbing a broader band of light energy. Furthermore, this study pioneers a new approach to architecturally compatible and decorative thin-film photovoltaics.« less

Splitting of turbulent spot in transitional pipe flow

NASA Astrophysics Data System (ADS)

Wu, Xiaohua; Moin, Parviz; Adrian, Ronald J.

2017-11-01

Recent study (Wu et al., PNAS, 1509451112, 2015) demonstrated the feasibility and accuracy of direct computation of the Osborne Reynolds' pipe transition problem without the unphysical, axially periodic boundary condition. Here we use this approach to study the splitting of turbulent spot in transitional pipe flow, a feature first discovered by E.R. Lindgren (Arkiv Fysik 15, 1959). It has been widely believed that spot splitting is a mysterious stochastic process that has general implications on the lifetime and sustainability of wall turbulence. We address the following two questions: (1) What is the dynamics of turbulent spot splitting in pipe transition? Specifically, we look into any possible connection between the instantaneous strain rate field and the spot splitting. (2) How does the passive scalar field behave during the process of pipe spot splitting. In this study, the turbulent spot is introduced at the inlet plane through a sixty degree wide numerical wedge within which fully-developed turbulent profiles are assigned over a short time interval; and the simulation Reynolds numbers are 2400 for a 500 radii long pipe, and 2300 for a 1000 radii long pipe, respectively. Numerical dye is tagged on the imposed turbulent spot at the inlet. Splitting of the imposed turbulent spot is detected very easily. Preliminary analysis of the DNS results seems to suggest that turbulent spot slitting can be easily understood based on instantaneous strain rate field, and such spot splitting may not be relevant in external flows such as the flat-plate boundary layer.

Evaluating a Split Processing Model of Visual Word Recognition: Effects of Orthographic Neighborhood Size

ERIC Educational Resources Information Center

Lavidor, Michal; Hayes, Adrian; Shillcock, Richard; Ellis, Andrew W.

2004-01-01

The split fovea theory proposes that visual word recognition of centrally presented words is mediated by the splitting of the foveal image, with letters to the left of fixation being projected to the right hemisphere (RH) and letters to the right of fixation being projected to the left hemisphere (LH). Two lexical decision experiments aimed to…

Numerical analyses for thinned fiber Bragg grating under uneven surrounding refractive index environment

NASA Astrophysics Data System (ADS)

Luo, Bin-bin; Zhao, Ming-fu; Zhou, Xiao-jun; Huang, De-yi; Wang, Shao-fei; Cao, Xue-mei

2011-12-01

Based on the fiber waveguide models, a modified transfer matrix method was utilized to calculate the reflection spectrum of the thinned fiber Bragg grating (ThFBG) under the uneven surrounding refractive index (SRI) environment. Tow SRI ranges, including the high SRI region (from 1.42 to the fiber cladding index) and the low ones (from 1.33 to about 1.36), were considered. Numerical results showed that the responsive characteristics of the reflectance spectrum of the ThFBG were closely related to the properties of the SRI distribution, first, the original reflection spectrum of the ThFBG would split into many tinny resonant peaks and the reflectance spectrums are asymmetric since the uneven SRI distributions, second, the number of the resonant peaks, the decline of the amplitude, and the degree of the asymmetric of the reflectance spectrums would increase as the increase in the SRI gradient and the D-value of the SRI between the tow ends of the ThFBG. The same numerical approach could be used to analyze the responsive characteristics of the ThFBG under the uneven medium environment where the SRI distribution was any other functions.

[Study on the vibrational spectra and XRD characters of Huanglong jade from Longling County, Yunnan Province].

PubMed

Pei, Jing-cheng; Fan, Lu-wei; Xie, Hao

2014-12-01

Based on the conventional test methods, the infrared absorption spectrum, Raman spectrum and X-ray diffraction (XRD) were employed to study the characters of the vibration spectrum and mineral composition of Huanglong jade. The testing results show that Huanglong jade shows typical vibrational spectrum characteristics of quartziferous jade. The main infrared absorption bands at 1162, 1076, 800, 779, 691, 530 and 466 cm(-1) were induced by the asymmetric stretching vibration, symmetrical stretching vibration and bending vibration of Si-O-Si separately. Especially the absorption band near 800 cm(-1) is split, which indicates that Huanglong jade has good crystallinity. In Raman spectrum, the main strong vibration bands at 463 and 355 cm(-1) were attributed to bending vibration of Si-O-Si. XRD test confirmed that Quartz is main mineral composition of Huanglong jade and there is a small amount of hematite in red color samples which induced the red color of Huanglong jade. This is the first report on the infrared, Raman and XRD spectra feature of Huanglong jade. It will provide a scientific basis for the identification, naming and other research for huanglong jade.

Experimental study of the embryogenesis of gastrointestinal duplication and enteric cyst.

PubMed

Emura, Takaki; Hashizume, Kohei; Asashima, Makoto

2003-05-01

The theory of gastrointestinal duplication and enteric cyst embryogenesis was verified by examining the developmental process of this experimentally induced anomaly. In Cynopus pyrrhogaster (amphibian) embryos (stage 18), the dorsal midline structures (including the neural plate and notochord) were split regionally to induce partial separation of the notochord and gut anlage endoderm herniation between the split elements of the notochord. Following this procedure, the embryonic development was traced morphologically and histologically. Control embryos were cultured without the procedure. Following the incubation and breeding period, gastrointestinal duplication and enteric cysts were observed with vertebral anomaly, spina bifida, split cord malformation and subcutaneous manifestations in the mature animals. The combination of anomalies that was observed in these experimental animals is consistent with that found in "split notochord syndrome." No abnormal morphology or histology was observed in the control group. The embryogenetic theory of gastrointestinal duplication and enteric cysts was thus verified by simulating the partial separation of the notochord, which induced split notochord syndrome in laboratory animals. The results indicate that gastrointestinal duplication and enteric cysts may arise through a process of herniation of the gut anlage endoderm between split elements of the notochord.

Complex seismic anisotropy beneath Germany from shear wave splitting and surface wave models

NASA Astrophysics Data System (ADS)

Campbell, L.; Long, M. D.; Becker, T. W.; Lebedev, S.

2013-12-01

Seismic anisotropy beneath stable continental interiors likely reflects a host of processes, including deformation in the lower crust, frozen anisotropy from past deformation processes in the lithospheric mantle, and present-day mantle flow in the asthenosphere. Because the anisotropic structure beneath continental interiors is generally complicated and often exhibits heterogeneity both laterally and with depth, a complete characterization of anisotropy and its interpretation in terms of deformational processes is challenging. In this study, we aim to expand our understanding of continental anisotropy by characterizing in detail the geometry and strength of azimuthal anisotropy beneath Germany and the surrounding region, using a combination of shear wave splitting and surface wave constraints. We utilize data from long-running broadband stations in and around Germany, collected from a variety of national and temporary European networks. We measure the splitting of SKS, SKKS, and PKS phases, with the aim of obtaining the best possible backazimuthal coverage. Preliminary results indicate that anisotropy beneath Germany is generally complex; we observe shear wave splitting patterns that are complicated and are inconsistent with a single horizontal layer of anisotropy beneath the station. Observed delay times are generally small (<1 sec), and there is a preponderance of null *KS arrivals in the dataset, with null measurements detected over a fairly large range of backazimuths. We also observe dramatic differences in splitting patterns over relatively short horizontal distances. Although we note backazimuthal variations in splitting at several stations, we do not observe a clear 90-degree periodicity that one would expect for the case of multiple anisotropic layers. We are currently carrying out comparisons between our observed splitting patterns and those predicted from tomographic models of azimuthal anisotropy derived from surface wave observations. The ultimate goal of this work is to combine different types of observations (shear wave splitting, surface wave models, and eventually anisotropic receiver function analysis) to place precise constraints on the anisotropic structure beneath Germany, and to interpret this structure in terms of on-going and past deformational processes in the crust and mantle.

Optical study of a spectrum splitting solar concentrator based on a combination of a diffraction grating and a Fresnel lens

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

Michel, Céline, E-mail: cmichel@ulg.ac.be; Habraken, Serge; Hololab, University of Liège, Allée du 6 Août, 17

2015-09-28

This paper presents recent improvements of our new solar concentrator design for space application. The concentrator is based on a combination of a diffraction grating (blazed or lamellar) coupled with a Fresnel lens. Thanks to this diffractive/refractive combination, this optical element splits spatially and spectrally the light and focus approximately respectively visible light and IR light onto electrically independent specific cells. It avoid the use of MJs cells and then also their limitations like current matching and lattice matching conditions, leading theoretically to a more tolerant system. The concept is reminded, with recent optimizations, ideal and more realistic results, andmore » the description of an experimental realization highlighting the feasibility of the concept and the closeness of theoretical and experimental results.« less

Direct observation of the discrete energy spectrum of two lanthanide-based single-chain magnets by far-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Haas, Sabrina; Heintze, Eric; Zapf, Sina; Gorshunov, Boris; Dressel, Martin; Bogani, Lapo

2014-05-01

The far-infrared optical transmission has been studied for two lanthanide-based single-chain magnets DyPhOPh and TbPhOPh in the frequency range between 3 and 80 cm-1. The spectra were acquired at temperatures between 2 and 80 K and magnetic fields up to 6 T. Based on their magnetic field dependence in DyPhOPh two of the observed absorption lines are identified as transitions inside the crystal field split Dy3+ ground multiplet 6H15/2, coupled to the neighboring spins. In TbPhOPh one transition was observed inside the crystal-field-split Tb3+ ground multiplet 7F6. The results allow a spectroscopic investigation of the role of single-ion anisotropy and exchange in Glauber dynamics.

Antiferromagnetic Ordering in Organic Conductor λ-(BEDT-TTF)2GaCl4 Probed by 13C NMR

NASA Astrophysics Data System (ADS)

Saito, Yohei; Fukuoka, Shuhei; Kobayashi, Takuya; Kawamoto, Atsushi; Mori, Hatsumi

2018-01-01

The ground state of λ-(BEDT-TTF)2GaCl4, which has the same structure as the organic superconductor λ-(BETS)2GaCl4, was investigated by magnetic susceptibility and 13C NMR measurements. The temperature dependence of the magnetic susceptibility revealed an antiferromagnetic (AF) correlation with J/kB ≃ 98 K. NMR spectrum splitting and the divergence of 1/T1 were observed at approximately 13 K, which is associated with the AF transition. We found that the AF structure is commensurate according to discrete NMR peak splitting, suggesting that the ground state of λ-(BEDT-TTF)2GaCl4 is an AF dimer-Mott insulating state. Our results suggest that the superconducting phase of λ-type salts would be located near the AF insulating phase.

Photocatalytic water splitting: Materials design and high-throughput screening of molecular compositions

NASA Astrophysics Data System (ADS)

Khnayzer, Rony S.

Due to the expected increases on energy demand in the near future, the development of new catalytic molecular compositions and materials capable of directly converting water, with the aid of solar photons, into hydrogen becomes obviated. Hydrogen is a combustible fuel and precious high-energy feedstock chemical. However, for the water-splitting reaction to proceed efficiently and economically enough for large-scale application, efficient light-absorbing sensitizers and water splitting catalysts are required. To study the kinetics of the water reduction reaction, we have used titania (TiO2) nanoparticles as a robust scaffold to photochemically grow platinum (Pt) nanoparticles from a unique surface-anchored molecular precursor Pt(dcbpy)Cl2 [dcbpy = 4,4'-dicarboxylic acid-2,2'-bipyridine]. The hybrid Pt/TiO 2 nanomaterials obtained were shown to be a superior water reduction catalyst (WRC) in aqueous suspensions when compared with the benchmark platinized TiO2. In addition, cobalt phosphate (CoPi) water oxidation catalyst (WOC) was photochemically assembled on the surface of TiO2, and its structure and mechanism of activity showed resemblance to the established electrochemically grown CoPi material. Both WRC and WOC described above possessed near unity Faradaic efficiency for hydrogen and oxygen production respectively, and were fully characterized by electron microscopy, x-ray absorption spectroscopy, electrochemistry and photochemistry. While there are established materials and molecules that are able to drive water splitting catalysis, some of these efficient semiconductors, including titanium dioxide (TiO2) and tungsten trioxide (WO3), are only able to absorb high-energy (ultraviolet or blue) photons. This high-energy light represents merely a fraction of the solar spectrum that strikes the earth and the energy content of those remaining photons is simply wasted. A strategy to mitigate this problem has been developed over the years in our laboratory. Briefly, photons of low energy are converted into higher energy light using a process termed photon upconversion. Using this technique, low energy photons supplied by the sun can be converted into light of appropriate energy to trigger electronic transitions in high energy absorbing photoactive materials without any chemical modification of the latter. We have shown, that this technology is capable of upconverting visible sunlight to sensitize wide-bandgap semiconductors such as WO3, subsequently extending the photoaction of these materials to cover a larger portion of the solar spectrum. Besides the engineering of different compositions that serve as either sensitizers or catalysts in these solar energy conversion schemes, we have designed an apparatus for parallel high-throughput screening of these photocatalytic compositions. This combinatorial approach to solar fuels photocatalysis has already led to unprecedented fundamental understanding of the generation of hydrogen gas from pure water. The activity of a series of new Ru(II) sensitizers along with Co(II) molecular WRCs were optimized under visible light excitation utilizing different experimental conditions. The multi-step mechanism of activity of selected compositions was further elucidated by pump-probe transient absorption spectroscopy.

Numerical simulation and experiment on split tungsten carbide cylinder of high pressure apparatus

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

Yang, Yunfei; Li, Mingzhe, E-mail: limz@jlu.edu.cn; Wang, Bolong

2015-12-15

A new high pressure device with a split cylinder was investigated on the basis of the belt-type apparatus. The belt-type die is subjected to excessive tangential tensile stress and the tungsten carbide cylinder is easily damaged in the running process. Taking into account the operating conditions and material properties of the tungsten carbide cylinder, it is divided into 6 blocks to eliminate the tangential tensile stress. We studied two forms of the split type: radial split and tangential split. Simulation results indicate that the split cylinder has more uniform stress distribution and smaller equivalent stress compared with the belt-type cylinder.more » The inner wall of the tangential split cylinder is in the situation that compressive stress is distributed in the axial, radial, and tangential directions. It is similar to the condition of hydrostatic pressure, and it is the best condition for tungsten carbide materials. The experimental results also verify that the tangential split die can bear the highest chamber pressure. Therefore, the tangential split structure can increase the pressure bearing capacity significantly.« less

Quasi-Fermi level splitting and sub-bandgap absorptivity from semiconductor photoluminescence

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

Katahara, John K.; Hillhouse, Hugh W., E-mail: h2@uw.edu

A unified model for the direct gap absorption coefficient (band-edge and sub-bandgap) is developed that encompasses the functional forms of the Urbach, Thomas-Fermi, screened Thomas-Fermi, and Franz-Keldysh models of sub-bandgap absorption as specific cases. We combine this model of absorption with an occupation-corrected non-equilibrium Planck law for the spontaneous emission of photons to yield a model of photoluminescence (PL) with broad applicability to band-band photoluminescence from intrinsic, heavily doped, and strongly compensated semiconductors. The utility of the model is that it is amenable to full-spectrum fitting of absolute intensity PL data and yields: (1) the quasi-Fermi level splitting, (2) themore » local lattice temperature, (3) the direct bandgap, (4) the functional form of the sub-bandgap absorption, and (5) the energy broadening parameter (Urbach energy, magnitude of potential fluctuations, etc.). The accuracy of the model is demonstrated by fitting the room temperature PL spectrum of GaAs. It is then applied to Cu(In,Ga)(S,Se){sub 2} (CIGSSe) and Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) to reveal the nature of their tail states. For GaAs, the model fit is excellent, and fitted parameters match literature values for the bandgap (1.42 eV), functional form of the sub-bandgap states (purely Urbach in nature), and energy broadening parameter (Urbach energy of 9.4 meV). For CIGSSe and CZTSSe, the model fits yield quasi-Fermi leveling splittings that match well with the open circuit voltages measured on devices made from the same materials and bandgaps that match well with those extracted from EQE measurements on the devices. The power of the exponential decay of the absorption coefficient into the bandgap is found to be in the range of 1.2 to 1.6, suggesting that tunneling in the presence of local electrostatic potential fluctuations is a dominant factor contributing to the sub-bandgap absorption by either purely electrostatic (screened Thomas-Fermi) or a photon-assisted tunneling mechanism (Franz-Keldysh). A Gaussian distribution of bandgaps (local E{sub g} fluctuation) is found to be inconsistent with the data. The sub-bandgap absorption of the CZTSSe absorber is found to be larger than that for CIGSSe for materials that yield roughly equivalent photovoltaic devices (8% efficient). Further, it is shown that fitting only portions of the PL spectrum (e.g., low energy for energy broadening parameter and high energy for quasi-Fermi level splitting) may lead to significant errors for materials with substantial sub-bandgap absorption and emission.« less

Creating ensembles of oblique decision trees with evolutionary algorithms and sampling

DOEpatents

Cantu-Paz, Erick [Oakland, CA; Kamath, Chandrika [Tracy, CA

2006-06-13

A decision tree system that is part of a parallel object-oriented pattern recognition system, which in turn is part of an object oriented data mining system. A decision tree process includes the step of reading the data. If necessary, the data is sorted. A potential split of the data is evaluated according to some criterion. An initial split of the data is determined. The final split of the data is determined using evolutionary algorithms and statistical sampling techniques. The data is split. Multiple decision trees are combined in ensembles.

Tablet Splitting of Antiepileptic Drugs in Pediatric Epilepsy: Potential Effect on Plasma Drug Concentrations.

PubMed

Nidanapu, Ravi Prasad; Rajan, Sundaram; Mahadevan, Subramanian; Gitanjali, Batmanabane

2016-12-01

Tablet splitting is the process of dividing a tablet into portions to obtain a prescribed dose of medication. Very few studies have investigated whether split parts of a tablet deliver the expected amount of drug to patients. Our objectives were to evaluate the split parts of adult-dose tablet formulations for percentage of weight deviation, weight uniformity, weight loss, drug content, and the content uniformity of four antiepileptic drugs (AEDs) prescribed to pediatric patients. We also measured AED plasma concentrations in the children. We chose to study first-line AEDs (phenytoin sodium [PHE], sodium valproate [SVA], carbamazepine, and phenobarbitone) as they are routinely prescribed in India. We asked caregivers to perform the same splitting process they follow in their homes on three whole tablets during their routine visit to the outpatient department. After caregivers split the tablets, we studied the weight and content of the split parts. We also used high-performance liquid chromatography to study plasma drug concentrations in children who had received split AEDs for at least 4 months. A total of 168 caregivers participated in the study, and we analyzed 1098 split tablet parts. In total, 539 (49.0 %) split parts were above the specified limit of the 2010 Indian Pharmacopeia (IP) acceptable percentage weight deviation (PHE 169 [48.8 %], SVA 187 [51.9 %], carbamazepine 56 [41.1 %], phenobarbitone 127 [49.6 %]); 456 (41.5 %) split parts were outside the proxy IP specification for drug content (PHE 135 [39.0 %], SVA 140 [38.8 %], carbamazepine 51 [37.5 %], phenobarbitone 130 [50.7 %]), and 253 split parts were outside the acceptable content uniformity range of <85 % and >115 % (PHE 85 [24.5 %], SVA 98 [27.2 %], carbamazepine 14 [10.2 %], phenobarbitone 56 [21.8 %]). In total, 130 (72.2 %) patients had plasma drug concentrations outside the therapeutic range (PHE 36 [72.0 %], SVA 39 [78.0 %], carbamazepine 34 [68.0 %], phenobarbitone 21 [70.0 %]). Splitting adult-dosage formulations of AEDs results in patients not receiving the optimal dose. Plasma drug concentrations are also not optimal. Pediatric dosage formulations should be preferred to splitting adult-dosage formulations in pediatric epilepsy.

40 CFR 425.90 - Applicability; description of the retan-wet finish-splits subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE... resulting from any tannery which processes previously unhaired and tanned splits into finished leather by...

Duplication of the pituitary gland associated with multiple blastogenesis defects: Duplication of the pituitary gland (DPG)-plus syndrome. Case report and review of literature

PubMed Central

Manjila, Sunil; Miller, Erin A.; Vadera, Sumeet; Goel, Rishi K.; Khan, Fahd R.; Crowe, Carol; Geertman, Robert T.

2012-01-01

Background: Duplication of the pituitary gland (DPG) is a rare craniofacial developmental anomaly occurring during blastogenesis with postulated etiology such as incomplete twinning, teratogens, median cleft face syndrome or splitting of the notochord. The complex craniocaudal spectrum of blastogenesis defects associated with DPG is examined with an illustrative case. Case Description: We report for the first time in the medical literature some unique associations with DPG, such as a clival encephalocele, third cerebral peduncle, duplicate odontoid process and a double tongue with independent volitional control. This patient also has the previously reported common associations such as duplicated sella, cleft palate, hypertelorism, callosal agenesis, hypothalamic enlargement, nasopharyngeal teratoma, fenestrated basilar artery and supernumerary teeth. This study also reviews 37 cases of DPG identified through MEDLINE literature search from 1880 to 2011. It provides a detailed analysis of the current case through physical examination and imaging. Conclusion: The authors propose that the developmental deformities associated with duplication of pituitary gland (DPG) occur as part of a developmental continuum, not as chance associations. Considering the fact that DPG is uniquely and certainly present throughout the spectrum of these blastogenesis defects, we suggest the term DPG-plus syndrome. PMID:22439114

Tunneling-thermally activated vacancy diffusion mechanism in quantum crystals

NASA Astrophysics Data System (ADS)

Natsik, V. D.; Smirnov, S. N.

2017-10-01

We consider a quasiparticle model of a vacancy in a quantum crystal, with metastable quantum states localized at the lattice sites in potential wells of the crystal field. It is assumed that the quantum dynamics of such vacancies can be described in the semi-classical approximation, where its spectrum consists of a broad band with several split-off levels. The diffusive movement of the vacancy in the crystal volume is reduced to a sequence of tunneling and thermally activated hops between the lattice cites. The temperature dependence of the vacancy diffusion coefficient shows a monotonic decrease during cooling with a sharp transition from an exponential dependence that is characteristic of a high-temperature thermally activated diffusion, to a non-thermal tunneling process in the region of extremely low temperatures. Similar trends have been recently observed in an experimental study of mass-transfer in the 4He and 3He crystals [V. A. Zhuchkov et al., Low Temp. Phys. 41, 169 (2015); Low Temp. Phys. 42, 1075 (2016)]. This mechanism of vacancy diffusion and its analysis complement the concept of a diffusional flow of a defection-quasiparticle quantum gas with a band energy spectrum proposed by Andreev and Lifshitz [JETP 29, 1107 (1969)] and Andreev [Sov. Phys. Usp. 19, 137 (1976)].

Analysis of mercerization process based on the intensity change of deconvoluted resonances of (13)C CP/MAS NMR: Cellulose mercerized under cooling and non-cooling conditions.

PubMed

Miura, Kento; Nakano, Takato

2015-08-01

The area intensity change of C1, C4, and C6 in spectrum obtained by (13)C CP/MAS NMR and the mutual relationship between their changes were examined for cellulose samples treated with various concentrations of aqueous NaOH solutions under non-cooling and cooling conditions. The area intensity of C1-up and C6-down changed cooperatively with that of C4-down which corresponds to the crystallinity of samples: "-up" and "-down" are the up- and down- field component in a splitting peak of NMR spectrum, respectively. The intensity change of C1-up starts to decrease with decreasing in that of C4-down after that of C6-down is almost complete. These changes were more clearly observed for samples treated under cooling condition. It can be suggested that their characteristic change relates closely to the change in conformation of cellulose chains by induced decrystallization and the subsequent crystallization of cellulose II, and presumed that their changes at microscopic level relate to the macroscopic morphological changes such as contraction along the length of cellulose chains and recovery along the length. Copyright © 2015 Elsevier B.V. All rights reserved.

The application of experimental data to blade wake interaction noise prediction

NASA Technical Reports Server (NTRS)

Glegg, Stewart A. L.; Devenport, William J.

1991-01-01

Blade wake interaction noise (BWI) has been defined as the broadband noise generated by the ingestion of turbulent trailing tip vortices by helicopter rotors. This has been shown to be the dominant contributor to the subjectively important part of the acoustic spectrum for the approach stage of a helicopter flyover. A prediction method for BWI noise based on the calculated trailing vortex trajectories has been developed and estimates of the vortex turbulence have been made. These measurements were made on a trailing vortex from a split wing arrangement and did not give the spectrum of the velocity fluctuations. A recent experiment carried out to measure the turbulence associated with a trailing vortex and the application of the results to BWI noise prediction is described.

IUE spectrum of the IO torus - Identification of the 5S2-3P2,1 transition of S III

NASA Technical Reports Server (NTRS)

Moos, H. W.; Durrance, S. T.; Skinner, T. E.; Feldman, P. D.; Bertaux, J.-L.; Festou, M. C.

1983-01-01

A spectrum of a much higher quality than previously available has been obtained which shows emission features arising from S(+), S(++), S(+++), and an upper limit for O(++). The well-defined splitting of the 1729 A feature is seen as confirming its tentative identification as semiforbidden S III 5S2(0)-3P2,1. The lower contamination of S III 1199 A by H I 1216 A than in most previous IUE spectra of the Io torus makes possible an estimate of the S III 1729 A collision strength. The variation of these features with temperature and their possible presence in spectra of nebulae are discussed.

Spectrophotovoltaic orbital power generation

NASA Technical Reports Server (NTRS)

Onffroy, J. R.

1980-01-01

The feasibilty of a spectrophotovoltaic orbital power generation system that optically concentrates solar energy is demonstrated. A dichroic beam-splitting mirror is used to divide the solar spectrum into two wavebands. Absorption of these wavebands by GaAs and Si solar cell arrays with matched energy bandgaps increases the cell efficiency while decreasing the amount of heat that must be rejected. The projected cost per peak watt if this system is $2.50/W sub p.

Vertically integrated visible and near-infrared metasurfaces enabling an ultra-broadband and highly angle-resolved anomalous reflection.

PubMed

Gao, Song; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2018-06-21

An optical device with minimized dimensions, which is capable of efficiently resolving an ultra-broad spectrum into a wide splitting angle but incurring no spectrum overlap, is of importance in advancing the development of spectroscopy. Unfortunately, this challenging task cannot be easily addressed through conventional geometrical or diffractive optical elements. Herein, we propose and demonstrate vertically integrated visible and near-infrared metasurfaces which render an ultra-broadband and highly angle-resolved anomalous reflection. The proposed metasurface capitalizes on a supercell that comprises two vertically concatenated trapezoid-shaped aluminum antennae, which are paired with a metallic ground plane via a dielectric layer. Under normal incidence, reflected light within a spectral bandwidth of 1000 nm ranging from λ = 456 nm to 1456 nm is efficiently angle-resolved to a single diffraction order with no spectrum overlap via the anomalous reflection, exhibiting an average reflection efficiency over 70% and a substantial angular splitting of 58°. In light of a supercell pitch of 1500 nm, to the best of our knowledge, the micron-scale bandwidth is the largest ever reported. It is noted that the substantially wide bandwidth has been accomplished by taking advantage of spectral selective vertical coupling effects between antennae and ground plane. In the visible regime, the upper antenna primarily renders an anomalous reflection by cooperating with the lower antenna, which in turn cooperates with the ground plane and produces phase variations leading to an anomalous reflection in the near-infrared regime. Misalignments between the two antennae have been particularly inspected to not adversely affect the anomalous reflection, thus guaranteeing enhanced structural tolerance of the proposed metasurface.

Strain induced novel quantum magnetotransport properties of topological insulators

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

Ma, Ning, E-mail: maning@stu.xjtu.edu.cn; Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong University, Xi’an 710049; Zhang, Shengli, E-mail: zhangsl@mail.xjtu.edu.cn

Recent theoretical and experimental researches have revealed that the strained bulk HgTe can be regarded as a three-dimensional topological insulator (TI). Motivated by this, we explore the strain effects on the transport properties of the HgTe surface states, which are modulated by a weak 1D in-plane electrostatic periodic potential in the presence of a perpendicular magnetic field. We analytically derive the zero frequency (dc) diffusion conductivity for the case of quasielastic scattering in the Kubo formalism, and find that, in strong magnetic field regime, the Shubnikov–de Haas oscillations are superimposed on top of the Weiss oscillations due to the electricmore » modulation for null and finite strain. Furthermore, the strain is shown to remove the degeneracy in inversion symmetric Dirac cones on the top and bottom surfaces. This accordingly gives rise to the splitting and mixture of Landau levels, and the asymmetric spectrum of the dc conductivity. These phenomena, not known in a conventional 2D electron gas and even in a strainless TI and graphene, are a consequence of the anomalous spectrum of surface states in a fully stained TI. These results should be valuable for electronic and spintronic applications of TIs, and thus we fully expect to see them in the further experiment. - Highlights: • The strain removes the degeneracy in inversion symmetric Dirac cones. • The strain gives rise to the splitting and mixture of the Landau levels. • The strain leads to the asymmetric spectrum of the dc conductivity. • Shubnikov de Haas oscillations are shown to be superimposed on Weiss oscillations. • Interplay between strain and electric field causes different occupancy of TI states.« less

Effects of flavor-symmetry violation from staggered fermion lattice simulations of graphene

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

Giedt, Joel; Nayak, Saroj; Skinner, Andrew

2011-01-15

We analyze the effects of flavor splitting from staggered fermion lattice simulations of a low-energy effective theory for graphene. Both the unimproved action and the tadpole-improved action with a Naik term show significant flavor-symmetry breaking in the spectrum of the Dirac operator. Note that this is true even in the vicinity of the second-order phase transition point where it has been argued that the flavor-symmetry breaking should be small due to the continuum limit being approached. We show that at weaker couplings the flavor splitting is drastically reduced by stout link smearing, while this mechanism is ineffective at the strongermore » couplings relevant to suspended graphene. We also measure the average plaquette and describe how it calls for a reinterpretation of previous lattice Monte Carlo simulation results, due to tadpole improvement. After taking into account these effects, we conclude that previous lattice simulations are possibly indicative of an insulating phase, although the effective number of light flavors could be effectively less than two due to the flavor-splitting effects. If that is true, then simulations with truly chiral fermions (such as overlap fermions) are needed in order to settle the question.« less

Particulate photocatalysts for overall water splitting

NASA Astrophysics Data System (ADS)

Chen, Shanshan; Takata, Tsuyoshi; Domen, Kazunari

2017-10-01

The conversion of solar energy to chemical energy is a promising way of generating renewable energy. Hydrogen production by means of water splitting over semiconductor photocatalysts is a simple, cost-effective approach to large-scale solar hydrogen synthesis. Since the discovery of the Honda-Fujishima effect, considerable progress has been made in this field, and numerous photocatalytic materials and water-splitting systems have been developed. In this Review, we summarize existing water-splitting systems based on particulate photocatalysts, focusing on the main components: light-harvesting semiconductors and co-catalysts. The essential design principles of the materials employed for overall water-splitting systems based on one-step and two-step photoexcitation are also discussed, concentrating on three elementary processes: photoabsorption, charge transfer and surface catalytic reactions. Finally, we outline challenges and potential advances associated with solar water splitting by particulate photocatalysts for future commercial applications.

Integrating a Semitransparent, Fullerene-Free Organic Solar Cell in Tandem with a BiVO4 Photoanode for Unassisted Solar Water Splitting.

PubMed

Peng, Yuelin; Govindaraju, Gokul V; Lee, Dong Ki; Choi, Kyoung-Shin; Andrew, Trisha L

2017-07-12

We report an unassisted solar water splitting system powered by a diketopyrrolopyrrole (DPP)-containing semitransparent organic solar cell. Two major merits of this fullerene-free solar cell enable its integration with a BiVO 4 photoanode. First is the high open circuit voltage and high fill factor displayed by this single junction solar cell, which yields sufficient power to effect water splitting when serially connected to an appropriate electrode/catalyst. Second, the wavelength-resolved photoaction spectrum of the DPP-based solar cell has minimal overlap with that of the BiVO 4 photoanode, thus ensuring that light collection across these two components can be optimized. The latter feature enables a new water splitting device configuration wherein the solar cell is placed first in the path of incident light, before the BiVO 4 photoanode, although BiVO 4 has a wider bandgap. This configuration is accessed by replacing the reflective top electrode of the standard DPP-based solar cell with a thin metal film and an antireflection layer, thus rendering the solar cell semitransparent. In this configuration, incident light does not travel through the aqueous electrolyte to reach the solar cell or photoanode, and therefore, photon losses due to the scattering of water are reduced. Moreover, this new configuration allows the BiVO 4 photoanode to be back-illuminated, i.e., through the BiVO 4 /back contact interface, which leads to higher photocurrents compared to front illumination. The combination of a semitransparent single-junction solar cell and a BiVO 4 photoanode coated with oxygen evolution catalysts in a new device configuration yielded an unassisted solar water splitting system with a solar-to-hydrogen conversion efficiency of 2.2% in water.

Single and multi-band electromagnetic induced transparency-like metamaterials with coupled split ring resonators

NASA Astrophysics Data System (ADS)

Bagci, Fulya; Akaoglu, Baris

2017-08-01

We present a metamaterial configuration exhibiting single and multi-band electromagnetic induced transparency (EIT)-like properties. The unit cell of the single band EIT-like metamaterial consists of a multi-split ring resonator surrounded by a split ring resonator. The multi-split ring resonator acts as a quasi-dark or dark resonator, depending on the polarization of the incident wave, and the split ring resonator serves as the bright resonator. Combination of these two resonators results in a single band EIT-like transmission inside the stop band. EIT-like transmission phenomenon is also clearly observed in the measured transmission spectrum at almost the same frequencies for vertical and horizontal polarized waves, and the numerical results are verified for normal incidence. Moreover, multi-band transmission windows are created within a wide band by combining the two slightly different single band EIT-like metamaterial unit cells that exhibit two different coupling strengths inside a supercell configuration. Group indices as high as 123 for single band and 488 for tri-band transmission, accompanying with high transmission rates (over 80%), are achieved, rendering the metamaterial very suitable for multi-band slow light applications. It is shown that the group delay of the propagating wave can be increased and dynamically controlled by changing the polarization angle. Multi-band EIT-like transmission is also verified experimentally, and a good agreement with simulations is obtained. The proposed novel methodology for obtaining multi-band EIT, which takes advantage of a supercell configuration by hosting slightly different configured unit cells, can be utilized for easily formation and manipulation of multi-band transmission windows inside a stop band.

SplitRacer - a new Semi-Automatic Tool to Quantify And Interpret Teleseismic Shear-Wave Splitting

NASA Astrophysics Data System (ADS)

Reiss, M. C.; Rumpker, G.

2017-12-01

We have developed a semi-automatic, MATLAB-based GUI to combine standard seismological tasks such as the analysis and interpretation of teleseismic shear-wave splitting. Shear-wave splitting analysis is widely used to infer seismic anisotropy, which can be interpreted in terms of lattice-preferred orientation of mantle minerals, shape-preferred orientation caused by fluid-filled cracks or alternating layers. Seismic anisotropy provides a unique link between directly observable surface structures and the more elusive dynamic processes in the mantle below. Thus, resolving the seismic anisotropy of the lithosphere/asthenosphere is of particular importance for geodynamic modeling and interpretations. The increasing number of seismic stations from temporary experiments and permanent installations creates a new basis for comprehensive studies of seismic anisotropy world-wide. However, the increasingly large data sets pose new challenges for the rapid and reliably analysis of teleseismic waveforms and for the interpretation of the measurements. Well-established routines and programs are available but are often impractical for analyzing large data sets from hundreds of stations. Additionally, shear wave splitting results are seldom evaluated using the same well-defined quality criteria which may complicate comparison with results from different studies. SplitRacer has been designed to overcome these challenges by incorporation of the following processing steps: i) downloading of waveform data from multiple stations in mseed-format using FDSNWS tools; ii) automated initial screening and categorizing of XKS-waveforms using a pre-set SNR-threshold; iii) particle-motion analysis of selected phases at longer periods to detect and correct for sensor misalignment; iv) splitting analysis of selected phases based on transverse-energy minimization for multiple, randomly-selected, relevant time windows; v) one and two-layer joint-splitting analysis for all phases at one station by simultaneously minimizing their transverse energy - this includes the analysis of null measurements. vi) comparison of results with theoretical splitting parameters determined for one, two, or continuously-varying anisotropic layer(s). Examples for the application of SplitRacer will be presented.

Signal processing for a single detector MOEMS based NIR micro spectrometer

NASA Astrophysics Data System (ADS)

Heberer, Andreas; Grüger, Heinrich; Zimmer, Fabian; Schenk, Harald; Kenda, Andreas; Frank, Albert; Scherf, Werner

2005-10-01

The examination of spectra in the NIR range is necessary for applications like process control, element analysis or medical systems. Typically integrated NIR spectrometers are based on optical setups with diffraction grating and detector arrays. The main disadvantage is price and availability of NIR array InGaAs-based detectors. The implementation of a scanning grating chip realized in a MOEMS technology which integrates the diffractive element makes it possible to detect spectra with single detectors time resolved. Either simple InGaAs photodiodes or cooled detectors may be used. The set up is a shrinked Czerny-Turner spectrometer. The light is coupled in by an optical fibre. After focussing the light passes the scanning grating moving at 150-500 Hz in a sinusoidal way. There it is split off in the different wavelength, the monochrome intensity is caught by a second mirror and led to the detector. The detector signal is amplified by a transimpedance stage and converted to digital with 12 bit resolution. The main part of the signal processing is done by a digital signal processor, which is used to unfold the sinusoidal position and calculate the final spectra. The data rate can be up to 3 MHz, then a spectrum is acquired every 2ms by using a 500Hz Mirror. Using the DSP, the spectrometer can operate autarkic without any PC. Then the spectrum is display on a 160 x 80 pixel graphic LCD. A keypad is used to control the functions. For communication a USB port is included, additional interfaces can be realized by a 16-pin expansion port, which is freely programmable, by the system firmware.

The turbulent cascade of individual eddies

NASA Astrophysics Data System (ADS)

Huertas-Cerdeira, Cecilia; Lozano-Durán, Adrián; Jiménez, Javier

2014-11-01

The merging and splitting processes of Reynolds-stress carrying structures in the inertial range of scales are studied through their time-resolved evolution in channels at Reλ = 100 - 200 . Mergers and splits coexist during the whole life of the structures, and are responsible for a substantial part of their growth and decay. Each interaction involves two or more eddies and results in little overall volume loss or gain. Most of them involve a small eddy that merges with, or splits from, a significantly larger one. Accordingly, if merge and split indexes are respectively defined as the maximum number of times that a structure has merged from its birth or will split until its death, the mean eddy volume grows linearly with both indexes, suggesting an accretion process rather than a hierarchical fragmentation. However, a non-negligible number of interactions involve eddies of similar scale, with a second probability peak of the volume of the smaller parent or child at 0.3 times that of the resulting or preceding structure. Funded by the Multiflow project of the ERC.

External quantum efficiency exceeding 100% in a singlet-exciton-fission-based solar cell

NASA Astrophysics Data System (ADS)

Baldo, Marc

2013-03-01

Singlet exciton fission can be used to split a molecular excited state in two. In solar cells, it promises to double the photocurrent from high energy photons, thereby breaking the single junction efficiency limit. We demonstrate organic solar cells that exploit singlet exciton fission in pentacene to generate more than one electron per incident photon in the visible spectrum. Using a fullerene acceptor, a poly(3-hexylthiophene) exciton confinement layer, and a conventional optical trapping scheme, the peak external quantum efficiency is (109 +/-1)% at λ = 670 nm for a 15-nm-thick pentacene film. The corresponding internal quantum efficiency is (160 +/-10)%. Independent confirmation of the high internal efficiency is obtained by analysis of the magnetic field effect on photocurrent, which determines that the triplet yield approaches 200% for pentacene films thicker than 5 nm. To our knowledge, this is the first solar cell to generate quantum efficiencies above 100% in the visible spectrum. Alternative multiple exciton generation approaches have been demonstrated previously in the ultraviolet, where there is relatively little sunlight. Singlet exciton fission differs from these other mechanisms because spin conservation disallows the usual dominant loss process: a thermal relaxation of the high-energy exciton into a single low-energy exciton. Consequently, pentacene is efficient in the visible spectrum at λ = 670 nm because only the collapse of the singlet exciton into twotriplets is spin-allowed. Supported as part of the Center for Excitonics, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001088.

Materials-Related Aspects of Thermochemical Water and Carbon Dioxide Splitting: A Review

PubMed Central

Roeb, Martin; Neises, Martina; Monnerie, Nathalie; Call, Friedemann; Simon, Heike; Sattler, Christian; Schmücker, Martin; Pitz-Paal, Robert

2012-01-01

Thermochemical multistep water- and CO2-splitting processes are promising options to face future energy problems. Particularly, the possible incorporation of solar power makes these processes sustainable and environmentally attractive since only water, CO2 and solar power are used; the concentrated solar energy is converted into storable and transportable fuels. One of the major barriers to technological success is the identification of suitable active materials like catalysts and redox materials exhibiting satisfactory durability, reactivity and efficiencies. Moreover, materials play an important role in the construction of key components and for the implementation in commercial solar plants. The most promising thermochemical water- and CO2-splitting processes are being described and discussed with respect to further development and future potential. The main materials-related challenges of those processes are being analyzed. Technical approaches and development progress in terms of solving them are addressed and assessed in this review.

The Rotational Spectrum of Singly and Doubly 13C-SUBSTITUTED Dimethylether

NASA Astrophysics Data System (ADS)

Koerber, Monika; Endres, Christian P.; Lewen, Frank; Giesen, Thomas F.; Schlemmer, Stephan; Pohl, Roland; Klein, Axel

2010-06-01

Dimethylether (DME) is a nearly prolate asymmetric top with two internal rotors (methyl groups) which undergo periodic large amplitude motions and show a complicated torsional splitting of each rotational energy level. Due to its complex spectrum and its high abundance in hot cores such as Orion KL or Sagittarius B2 at temperatures exceeding 100 K, DME is very prominent in astronomical line surveys and contributes to spectral line confusion of such sources. The interpretation of astronomical observations therefore depends on the knowledge of accurate rest frequencies and reliable intensities. Precise predictions for the ground state of DME's main isotopologue are now available up to 2.1 THz In contrast, very little is known about 13C-substituted DME. Only a few data are available on singly 13C-substituted DME, 12CH_3O13CH_3. However, no data are available on doubly 13C-substituted DME, (13CH_3)_2O, yet. While in (13CH_3)_2O the two internal rotating methyl groups are equivalent and the splitting of rotational energy levels into four substates is comparable to the main isotopologue, singly 13C-substituted DME has two non-equivalent internal rotors resulting in torsional splitting of rotational energy levels into five substates. The purpose of our new laboratory measurements is to extend the knowledge on the astrophysically relevant species 12CH_3O13CH_3. To analyze the complicated spectrum resulting from a 13C-enriched sample of DME, containing all different 13C-substituted species as well as the main isotopologue, also precise data on doubly 13C-substituted DME are inevitable. We performed measurements in the frequency region 35-120 GHz using an all solid state spectrometer. Rotational as well as torsional parameters have been obtained for (13CH_3)_2O as well as 12CH_3O13CH_3 by fitting the assigned transitions to an effective rotational Hamiltonian introduced by Peter Groner. C. Comito et al., Astrophys. J. Suppl. Ser. 156, 127-167 (2005) C. P. Endres et al., Astronomy & Astrophysics 504, 635-640 (2009) Y. Niide and M. Hayashi, J. Mol. Spectrosc. 220, 65-79 (2003) P. Groner, J. Chem. Phys. 107, 4483-4498 (1997).

Flux-split algorithms for flows with non-equilibrium chemistry and vibrational relaxation

NASA Technical Reports Server (NTRS)

Grossman, B.; Cinnella, P.

1990-01-01

The present consideration of numerical computation methods for gas flows with nonequilibrium chemistry thermodynamics gives attention to an equilibrium model, a general nonequilibrium model, and a simplified model based on vibrational relaxation. Flux-splitting procedures are developed for the fully-coupled inviscid equations encompassing fluid dynamics and both chemical and internal energy-relaxation processes. A fully coupled and implicit large-block structure is presented which embodies novel forms of flux-vector split and flux-difference split algorithms valid for nonequilibrium flow; illustrative high-temperature shock tube and nozzle flow examples are given.

Microcracking, microcrack-induced delamination, and longitudinal splitting of advanced composite structures

NASA Technical Reports Server (NTRS)

Nairn, John A.

1992-01-01

A combined analytical and experimental study was conducted to analyze microcracking, microcrack-induced delamination, and longitudinal splitting in polymer matrix composites. Strain energy release rates, calculated by a variational analysis, were used in a failure criterion to predict microcracking. Predictions and test results were compared for static, fatigue, and cyclic thermal loading. The longitudinal splitting analysis accounted for the effects of fiber bridging. Test data are analyzed and compared for longitudinal splitting and delamination under mixed-mode loading. This study emphasizes the importance of using fracture mechanics analyses to understand the complex failure processes that govern composite strength and life.

The LPM effect in sequential bremsstrahlung 2: factorization

DOE PAGES

Arnold, Peter; Chang, Han-Chih; Iqbal, Shahin

2016-09-13

The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g. overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is themore » case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; q approximation; large N c; and neglect for the moment of processes involving 4-gluon ver-tices) and explicitly compute the correction Δ dΓ/dx dy due to overlapping formation times.« less

Lithographically Patterned Nanoscale Electrodeposition of Plasmonic, Bimetallic, Semiconductor, Magnetic, and Polymer Nanoring Arrays

PubMed Central

2015-01-01

Large area arrays of magnetic, semiconducting, and insulating nanorings were created by coupling colloidal lithography with nanoscale electrodeposition. This versatile nanoscale fabrication process allows for the independent tuning of the spacing, diameter, and width of the nanorings with typical values of 1.0 μm, 750 nm, and 100 nm, respectively, and was used to form nanorings from a host of materials: Ni, Co, bimetallic Ni/Au, CdSe, and polydopamine. These nanoring arrays have potential applications in memory storage, optical materials, and biosensing. A modified version of this nanoscale electrodeposition process was also used to create arrays of split gold nanorings. The size of the split nanoring opening was controlled by the angle of photoresist exposure during the fabrication process and could be varied from 50% down to 10% of the ring circumference. The large area (cm2 scale) gold split nanoring array surfaces exhibited strong polarization-dependent plasmonic absorption bands for wavelengths from 1 to 5 μm. Plasmonic nanoscale split ring arrays are potentially useful as tunable dichroic materials throughout the infrared and near-infrared spectral regions. PMID:25553204

Mössbauer and XRD study of novel quaternary Sn-Fe-Co-Ni electroplated alloy

NASA Astrophysics Data System (ADS)

Kuzmann, E.; Sziráki, L.; Stichleutner, S.; Homonnay, Z.; Lak, G. B.; El-Sharif, M.; Chisholm, C. U.

2017-11-01

Constant current electrochemical deposition technique was used to obtain quaternary alloys of Sn-Fe-Co-Ni from a gluconate electrolyte, which to date have not been reported in the literature. For the characterization of electroplated alloys, 57Fe and 119Sn Conversion Electron Mössbauer Spectroscopy (CEMS), XRD and SEM/EDAX were used. XRD revealed the amorphous character of the novel Sn-Fe-Co-Ni electrodeposited alloys. 57Fe Mössbauer spectrum of quaternary deposit with composition of 37.0 at% Sn, 38.8 at% Fe, 16.8 at% Co and 7.4 at% Ni displayed a magnetically split sextet (B = 28.9T) with broad lines typical of iron bearing ferromagnetic amorphous alloys. Magnetically split 119Sn spectra reflecting a transferred hyperfine field (B = 2.3T) were also observed. New quaternary Sn-Fe-Co-Ni alloys were successfully prepared.

Loss for photoemission versus gain for Auger: Direct experimental evidence of crystal-field splitting and charge transfer in photoelectron spectroscopy

DOE PAGES

Woicik, J. C.; Weiland, C.; Rumaiz, A. K.

2015-05-29

Here, we find a 5 eV satellite in the Ti1s photoelectron spectrum of the transition-metal oxide SrTiO 3. This satellite appears in addition to the well-studied 13 eV structure that is typically associated with the Ti2p core line. We give direct experimental evidence that the presence of two satellites is due to the crystal-field splitting of the metal 3d orbitals. They originate from ligand 2pt 2g → metal3dt 2g and ligand 2pe g → metal 3de g monopole charge-transfer excitations within the sudden approximation of quantum mechanics. This assignment is made by the energetics of the resonant and high-energy thresholdmore » behaviors of the TiK–L 2L 3 Auger decay that follows Ti1s photoionization.« less

Unification and new particles at the LHC

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

Arkani-Hamed, Nima; D’Agnolo, Raffaele Tito; Low, Matthew

Precision gauge coupling uni cation is one of the primary quantitative successes of low energy or split supersymmetry. Preserving this success puts severe restrictions on possible matter and gauge sectors that might appear at collider-accessible energies. In this study we enumerate new gauge sectors which are compatible with uni cation, consisting of horizontal gauge groups acting on vector-like matter charged under the Standard Model. Interestingly, almost all of these theories are in the supersymmetric conformal window at high energies and con ne quickly after the superpartners are decoupled. For a range of scalar masses compatible with both moderately tuned andmore » minimally split supersymmetry, the con ning dynamics happen at the multi-TeV scale, leading to a spectrum of multiple spin-0 and spin-1 resonances accessible to the LHC, with unusual quantum numbers and striking decay patterns.« less

Parallel independent evolution of pathogenicity within the genus Yersinia

PubMed Central

Reuter, Sandra; Connor, Thomas R.; Barquist, Lars; Walker, Danielle; Feltwell, Theresa; Harris, Simon R.; Fookes, Maria; Hall, Miquette E.; Petty, Nicola K.; Fuchs, Thilo M.; Corander, Jukka; Dufour, Muriel; Ringwood, Tamara; Savin, Cyril; Bouchier, Christiane; Martin, Liliane; Miettinen, Minna; Shubin, Mikhail; Riehm, Julia M.; Laukkanen-Ninios, Riikka; Sihvonen, Leila M.; Siitonen, Anja; Skurnik, Mikael; Falcão, Juliana Pfrimer; Fukushima, Hiroshi; Scholz, Holger C.; Prentice, Michael B.; Wren, Brendan W.; Parkhill, Julian; Carniel, Elisabeth; Achtman, Mark; McNally, Alan; Thomson, Nicholas R.

2014-01-01

The genus Yersinia has been used as a model system to study pathogen evolution. Using whole-genome sequencing of all Yersinia species, we delineate the gene complement of the whole genus and define patterns of virulence evolution. Multiple distinct ecological specializations appear to have split pathogenic strains from environmental, nonpathogenic lineages. This split demonstrates that contrary to hypotheses that all pathogenic Yersinia species share a recent common pathogenic ancestor, they have evolved independently but followed parallel evolutionary paths in acquiring the same virulence determinants as well as becoming progressively more limited metabolically. Shared virulence determinants are limited to the virulence plasmid pYV and the attachment invasion locus ail. These acquisitions, together with genomic variations in metabolic pathways, have resulted in the parallel emergence of related pathogens displaying an increasingly specialized lifestyle with a spectrum of virulence potential, an emerging theme in the evolution of other important human pathogens. PMID:24753568

Nonlinear Midinfrared Photothermal Spectroscopy Using Zharov Splitting and Quantum Cascade Lasers.

PubMed

Mertiri, Alket; Altug, Hatice; Hong, Mi K; Mehta, Pankaj; Mertz, Jerome; Ziegler, Lawrence D; Erramilli, Shyamsunder

2014-08-20

We report on the mid-infrared nonlinear photothermal spectrum of the neat liquid crystal 4-octyl-4'-cyanobiphenyl (8CB) using a tunable Quantum Cascade Laser (QCL). The nonequilibrium steady state characterized by the nonlinear photothermal infrared response undergoes a supercritical bifurcation. The bifurcation, observed in heterodyne two-color pump-probe detection, leads to ultrasharp nonlinear infrared spectra similar to those reported in the visible region. A systematic study of the peak splitting as a function of absorbed infrared power shows the bifurcation has a critical exponent of 0.5. The observation of an apparently universal critical exponent in a nonequilibrium state is explained using an analytical model analogous of mean field theory. Apart from the intrinsic interest for nonequilibrium studies, nonlinear photothermal methods lead to a dramatic narrowing of spectral lines, giving rise to a potential new contrast mechanism for the rapidly emerging new field of mid-infrared microspectroscopy using QCLs.

Optical properties of BaY2F8:Ce3+

NASA Astrophysics Data System (ADS)

Fabeni, P.; di Martino, D.; Nikl, M.; Pazzi, G. P.; Sani, E.; Toncelli, A.; Tonelli, M.; Vedda, A.

2005-01-01

The optical properties of Ce3+-doped BaY2F8 crystals were investigated under selective laser excitation and X-ray irradiation. In both cases, the emission spectrum is dominated by the characteristic doublet transition from the lowest energy level of the 5d configuration to the spin-orbit split 2F ground state of Ce3+. Excitation bands at 4.1, 5.0, 5.9 and 6.2 eV, due to transitions between 4f and split 5d levels were observed. The emission time decay was satisfactorily analyzed by a single exponential component, characterized by a decay time of approximately 28 ns at 10 K and slightly increasing with temperature. A monotonic temperature quenching of the photo-luminescence intensity was observed; on the other hand, the temperature dependence of radio-luminescence intensity is modulated by the presence of shallow traps competing with Ce3+ ions in carrier trapping during irradiation.

Spin eigen-states of Dirac equation for quasi-two-dimensional electrons

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

Eremko, Alexander, E-mail: eremko@bitp.kiev.ua; Brizhik, Larissa, E-mail: brizhik@bitp.kiev.ua; Loktev, Vadim, E-mail: vloktev@bitp.kiev.ua

Dirac equation for electrons in a potential created by quantum well is solved and the three sets of the eigen-functions are obtained. In each set the wavefunction is at the same time the eigen-function of one of the three spin operators, which do not commute with each other, but do commute with the Dirac Hamiltonian. This means that the eigen-functions of Dirac equation describe three independent spin eigen-states. The energy spectrum of electrons confined by the rectangular quantum well is calculated for each of these spin states at the values of energies relevant for solid state physics. It is shownmore » that the standard Rashba spin splitting takes place in one of such states only. In another one, 2D electron subbands remain spin degenerate, and for the third one the spin splitting is anisotropic for different directions of 2D wave vector.« less

Nonlinear Midinfrared Photothermal Spectroscopy Using Zharov Splitting and Quantum Cascade Lasers

PubMed Central

2015-01-01

We report on the mid-infrared nonlinear photothermal spectrum of the neat liquid crystal 4-octyl-4′-cyanobiphenyl (8CB) using a tunable Quantum Cascade Laser (QCL). The nonequilibrium steady state characterized by the nonlinear photothermal infrared response undergoes a supercritical bifurcation. The bifurcation, observed in heterodyne two-color pump–probe detection, leads to ultrasharp nonlinear infrared spectra similar to those reported in the visible region. A systematic study of the peak splitting as a function of absorbed infrared power shows the bifurcation has a critical exponent of 0.5. The observation of an apparently universal critical exponent in a nonequilibrium state is explained using an analytical model analogous of mean field theory. Apart from the intrinsic interest for nonequilibrium studies, nonlinear photothermal methods lead to a dramatic narrowing of spectral lines, giving rise to a potential new contrast mechanism for the rapidly emerging new field of mid-infrared microspectroscopy using QCLs. PMID:25541620

Unification and new particles at the LHC

DOE PAGES

Arkani-Hamed, Nima; D’Agnolo, Raffaele Tito; Low, Matthew; ...

2016-11-14

Precision gauge coupling uni cation is one of the primary quantitative successes of low energy or split supersymmetry. Preserving this success puts severe restrictions on possible matter and gauge sectors that might appear at collider-accessible energies. In this study we enumerate new gauge sectors which are compatible with uni cation, consisting of horizontal gauge groups acting on vector-like matter charged under the Standard Model. Interestingly, almost all of these theories are in the supersymmetric conformal window at high energies and con ne quickly after the superpartners are decoupled. For a range of scalar masses compatible with both moderately tuned andmore » minimally split supersymmetry, the con ning dynamics happen at the multi-TeV scale, leading to a spectrum of multiple spin-0 and spin-1 resonances accessible to the LHC, with unusual quantum numbers and striking decay patterns.« less

The Zeeman splitting of bulk 2H-MoTe2 single crystal in high magnetic field

NASA Astrophysics Data System (ADS)

Sun, Yan; Zhang, Junpei; Ma, Zongwei; Chen, Cheng; Han, Junbo; Chen, Fangchu; Luo, Xuan; Sun, Yuping; Sheng, Zhigao

2017-03-01

A high magnetic field magneto-optical spectrum is utilized to study the A exciton of bulk 2H-MoTe2 single crystal. A clear Zeeman splitting of the A exciton is observed under high magnetic fields up to 41.68 T, and the g-factor (-2.09 ± 0.08) is deduced. Moreover, a high magnetic field enables us to obtain the quadratic diamagnetic shifts of the A exciton (0.486 μeV T-2). Accordingly, the binding energy, reduced mass, and radius of the A exciton were obtained by using both two and three dimensional models. Compared with other transition metal dichalcogenides (TMDs), the A exciton of bulk 2H-MoTe2 has a relatively small binding energy and larger exciton radius, which provide fundamental parameters for comprehensive understanding of excitons in TMDs as well as their future applications.

Theoretical study of high-Q Fano resonance and extrinsic chirality in an ultrathin Babinet-inverted metasurface

NASA Astrophysics Data System (ADS)

Wang, Feng; Wang, Zhengping; Shi, Jinhui

2014-10-01

A high-Q Fano resonance and giant extrinsic chirality have been demonstrated in an ultrathin Babinet-inverted metasurface composed of asymmetrical split ring apertures (ASRAs) perforated through a metal plate based on the full-wave simulations. The performance of the Fano resonance at normal incidence strongly depends on the asymmetry of the ASRA. The quality factor is larger than 1000 and the local field enhancement is an order of 104. For oblique incidence, giant extrinsic chirality can be achieved in the Babinet-inverted metasurface. It reveals a cross-polarization transmission band with a ripple-free peak and also a spectrum split for large angles of incidence. The electromagnetic response of the metasurface can be easily tuned via angles of incidence and asymmetry. The proposed ASRA metasurface is of importance to develop many metamaterial-based devices, such as filters and circular polarizers.

Water pair potential of near spectroscopic accuracy. II. Vibration-rotation-tunneling levels of the water dimer

NASA Astrophysics Data System (ADS)

Groenenboom, G. C.; Wormer, P. E. S.; van der Avoird, A.; Mas, E. M.; Bukowski, R.; Szalewicz, K.

2000-10-01

Nearly exact six-dimensional quantum calculations of the vibration-rotation-tunneling (VRT) levels of the water dimer for values of the rotational quantum numbers J and K ⩽2 show that the SAPT-5s water pair potential presented in the preceding paper (paper I) gives a good representation of the experimental high-resolution far-infrared spectrum of the water dimer. After analyzing the sensitivity of the transition frequencies with respect to the linear parameters in the potential we could further improve this potential by using only one of the experimentally determined tunneling splittings of the ground state in (H2O)2. The accuracy of the resulting water pair potential, SAPT-5st, is established by comparison with the spectroscopic data of both (H2O)2 and (D2O)2: ground and excited state tunneling splittings and rotational constants, as well as the frequencies of the intermolecular vibrations.

Structure and Rotation of the Solar Interior: Initial Results from the MDI Medium-L Program

NASA Technical Reports Server (NTRS)

Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.; DeForest, C.;

First High Resolution Analysis of the ν21 Band of Propane at 921.4 wn: Evidence of Large-Amplitude Tunnelling Effects

NASA Astrophysics Data System (ADS)

Perrin, Agnes; Kwabia Tchana, F.; Flaud, Jean-Marie; Manceron, Laurent; Demaison, Jean; Vogt, Natalja; Groner, Peter; Lafferty, Walter

2015-06-01

A high resolution (0.0015 wn) IR spectrum of propane, C_3H_8, has been recorded with synchrotron radiation at the French light source facility at SOLEIL coupled to a Bruker IFS-125 Fourier transform spectrometer. A preliminary analysis of the ν21 fundamental band (B1, CH3 rock) near 921.4 wn reveals that the rotational energy levels of 211 are split by interactions with the internal rotations of the methyl groups. Conventional analysis of this A-type band yielded band centers at 921.3724(38), 921.3821(33) and 921.3913(44) wn for the AA, EE and AE+EA tunneling splitting components, respectively. These torsional splittings most probably are due to anharmonic and/or Coriolis resonance coupling with nearby highly excited states of both internal rotations of the methyl groups. In addition, several vibrational-rotational resonances were observed that affect the torsional components in different ways. The analysis of the B-type band near 870 wn (ν8, sym. C-C stretch) which also contains split rovibrational transitions due to internal rotation is in progress. It is performed by using the effective rotational Hamiltonian method ERHAM with a code that allows prediction and least-squares fitting of such vibration-rotation spectra. A. Perrin et al., submitted to J. Mol. Spectrosc. P. Groner, J. Chem. Phys. 107 (1997) 4483; J. Mol. Spectrosc. 278 (2012) 52.

Nanoscale orbital excitations and the infrared spectrum of a molecular Mott insulator: A15-Cs3C60.

PubMed

Naghavi, S S; Fabrizio, M; Qin, T; Tosatti, E

2016-10-14

The quantum physics of ions and electrons behind low-energy spectra of strongly correlated molecular conductors, superconductors and Mott insulators is poorly known, yet fascinating especially in orbitally degenerate cases. The fulleride insulator Cs 3 C 60 (A15), one such system, exhibits infrared (IR) spectra with low temperature peak features and splittings suggestive of static Jahn-Teller distortions with a breakdown of orbital symmetry in the molecular site. That is puzzling, since there is no detectable static distortion, and because the features and splittings disappear upon modest heating, which they should not. Taking advantage of the Mott-induced collapse of electronic wavefunctions from lattice-extended to nanoscale localized inside a caged molecular site, we show that the unbroken spin and orbital symmetry of the ion multiplets explains the IR spectrum without adjustable parameters. This demonstrates the importance of a fully quantum treatment of nuclear positions and orbital momenta in the Mott insulator sites, dynamically but not statically distorted. The observed demise of these features with temperature is explained by the thermal population of a multiplet term whose nuclear positions are essentially undistorted, but whose energy is very low-lying. That term is in fact a scaled-down orbital excitation analogous to that of other Mott insulators, with the same spin 1/2 as the ground state, but with a larger orbital momentum of two instead of one.

Near sulfur L-edge X-ray absorption spectra of methanethiol in isolation and adsorbed on a Au(111) surface: a theoretical study using the four-component static exchange approximation.

PubMed

Villaume, Sebastien; Ekström, Ulf; Ottosson, Henrik; Norman, Patrick

2010-06-07

The relativistic four-component static exchange approach for calculation of near-edge X-ray absorption spectra has been reviewed. Application of the method is made to the Au(111) interface and the adsorption of methanethiol by a study of the near sulfur L-edge spectrum. The binding energies of the sulfur 2p(1/2) and 2p(3/2) sublevels in methanethiol are determined to be split by 1.2 eV due to spin-orbit coupling, and the binding energy of the 2p(3/2) shell is lowered from 169.2 eV for the isolated system to 167.4 and 166.7-166.8 eV for methanethiol in mono- and di-coordinated adsorption sites, respectively (with reference to vacuum). In the near L-edge X-ray absorption fine structure spectrum only the sigma*(S-C) peak at 166 eV remains intact by surface adsorption, whereas transitions of predominantly Rydberg character are largely quenched in the surface spectra. The sigma*(S-H) peak of methanethiol is replaced by low-lying, isolated, sigma*(S-Au) peak(s), where the number of peaks in the latter category and their splittings are characteristic of the local bonding situation of the sulfur.

Randomized, Split-Face/Décolleté Comparative Trial of Procedure Enhancement System for Fractional non-Ablative Laser Resurfacing Treatment.

PubMed

Robinson, Deanne Mraz; Frulla, Ashton P

2017-07-01

INTRODUCTION: A topical proprietary procedural enhancement system (PES) containing a combination of active ingredients including a tripeptide and hexapeptide (TriHex Technology™, Alastin Procedure Enhancement Invasive System, ALASTIN Skincare™, Inc., Carlsbad, CA) has been used successfully to aid in healing and improve symptomatology following resurfacing procedures.

METHODS: PES (Gentle Cleanser, Regenerating Skin Nectar with TriHex Technology™, Ultra Nourishing Moisturizer with TriHex Technology™, Soothe + Protect Recovery Balm, Broad Spectrum 30+ Sunscreen) was compared to a basic regimen (Aquaphor™, Cerave™ cleanser, Vanicream™, Alastin Broad Spectrum 30+ Sunscreen) in a split face/ décolleté trial following fractional non-ablative thulium-doped resurfacing treatment to the face or décolleté. The skin was pre-conditioned and treated during and after the procedure using the two regimens.

RESULTS: A blinded investigator rated the PES statistically superior to the basic regimen on healing post-laser treatment on day 4 based on lentigines, texture, and Global Skin Quality. Subjects also reported 'better looking and feeling' skin on the PES side.

CONCLUSION: PES appears to improve healing post-non ablative thulium-doped resurfacing treatment to the face/décolleté in comparison with standard of care.

J Drugs Dermatol. 2017;16(7):707-710.

Free-form Fresnel RXI-RR Köhler design for high-concentration photovoltaics with spectrum-splitting

NASA Astrophysics Data System (ADS)

Buljan, M.; Benítez, P.; Mohedano, R.; Miñano, J. C.; Sun, Y.; Falicoff, W.; Vilaplana, J.; Chaves, J.; Biot, G.; López, J.

2011-10-01

Development of a novel HCPV nonimaging concentrator with high concentration (>500x) and built-in spectrum splitting concept is presented. It uses the combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-Point-Contact (BPC) silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell's reflection. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded in it - Both the POE and SOE performing Köhler integration to produce light homogenization on the receiver. The band-pass filter transmits the IR photons in the 900-1200 nm band to the silicon cell. A design target of an "equivalent" cell efficiency ~46% is predicted using commercial 39% 3J and 26% Si cells. A projected CPV module efficiency of greater than 38% is achievable at a concentration level larger than 500X with a wide acceptance angle of +/-1°. A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ~100x and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J cell with a peak efficiency of 36.9%.

Excitons in strongly correlated oxide nanocrystals NicMg1-cO

NASA Astrophysics Data System (ADS)

Sokolov, V. I.; Churmanov, V. N.; Pustovarov, V. A.; Gruzdev, N. B.; Uimin, M. A.; Byzov, I. V.; Zatsepin, A. F.; Kuznetsova, J. A.

2018-05-01

This paper reports about excitons in strongly correlated oxide nanocrystals NicMg1-cO (c = 0.008 and c = 1). At 8 K two weak peaks were firstly observed in the optical density spectrum of NiO nanocrystals at the energies of 3.510 eV and 3.543 eV. The intensity of the peaks subsides with an increase of temperature and a decrease of nanoparticle sizes from 25 nm to 10 nm. The peaks were attributed to the formation of p-d charge transfer excitons {d9h}. A tunneling annihilation for {d9h} excitons diminishes their lifetime drastically, even at low temperatures. This fact is considered as an inherent feature in the p-d charge transfer excitons {d9h}, which makes them significantly different from the Wannier-Mott excitons for semiconductors with direct allowed transitions. We believe that energy shift between two peaks originates due to the spin-orbit splitting of the top of the valence band, equals 33 meV. In p-d charge transfer photoluminescence excitation spectrum of NicMg1-cO (c = 0.008), we have revealed two [d9h] exciton lines near the charge transfer band edge. Energy shift of these lines (equals 25 meV) is due to the spin-orbit splitting of MgO valence band top.

Rotational Spectrum of Sarin.

PubMed

Walker, A. R. Hight; Suenram, R. D.; Samuels, Alan; Jensen, James; Ellzy, Michael W.; Lochner, J. Michael; Zeroka, Daniel

2001-05-01

As part of an effort to examine the possibility of using molecular-beam Fourier-transform microwave spectroscopy to unambiguously detect and monitor chemical warfare agents, we report the first observation and assignment of the rotational spectrum of the nerve agent Sarin (GB) (Methylphosphonofluoridic acid 1-methyl-ethyl ester, CAS #107-44-8) at frequencies between 10 and 22 GHz. Only one of the two low-energy conformers of this organophosphorus compound (C(4)H(10)FO(2)P) was observed in the rotationally cold (T(rot)<2 K) molecular beam. The experimental asymmetric-rotor ground-state rotational constants of this conformer are A=2874.0710(9) MHz, B=1168.5776(4) MHz, C=1056.3363(4) MHz (Type A standard uncertainties are given, i.e., 1sigma), as obtained from a least-squares analysis of 74 a-, b-, and c-type rotational transitions. Several of the transitions are split into doublets due to the internal rotation of the methyl group attached to the phosphorus. The three-fold-symmetry barrier to internal rotation estimated from these splittings is 677.0(4) cm(-1). Ab initio electronic structure calculations using Hartree-Fock, density functional, and Moller-Plesset perturbation theories have also been made. The structure of the lowest-energy conformer determined from a structural optimization at the MP2/6-311G(**) level of theory is consistent with our experimental findings. Copyright 2001 Academic Press.

Rotational Spectrum of Sarin

NASA Astrophysics Data System (ADS)

Walker, A. R. Hight; Suenram, R. D.; Samuels, Alan; Jensen, James; Ellzy, Michael W.; Lochner, J. Michael; Zeroka, Daniel

2001-05-01

As part of an effort to examine the possibility of using molecular-beam Fourier-transform microwave spectroscopy to unambiguously detect and monitor chemical warfare agents, we report the first observation and assignment of the rotational spectrum of the nerve agent Sarin (GB) (Methylphosphonofluoridic acid 1-methyl-ethyl ester, CAS #107-44-8) at frequencies between 10 and 22 GHz. Only one of the two low-energy conformers of this organophosphorus compound (C4H10FO2P) was observed in the rotationally cold (Trot<2 K) molecular beam. The experimental asymmetric-rotor ground-state rotational constants of this conformer are A=2874.0710(9) MHz, B=1168.5776(4) MHz, C=1056.3363(4) MHz (Type A standard uncertainties are given, i.e., 1σ), as obtained from a least-squares analysis of 74 a-, b-, and c-type rotational transitions. Several of the transitions are split into doublets due to the internal rotation of the methyl group attached to the phosphorus. The three-fold-symmetry barrier to internal rotation estimated from these splittings is 677.0(4) cm-1. Ab initio electronic structure calculations using Hartree-Fock, density functional, and Moller-Plesset perturbation theories have also been made. The structure of the lowest-energy conformer determined from a structural optimization at the MP2/6-311G** level of theory is consistent with our experimental findings.

Electron spin relaxation governed by Raman processes both for Cu2+ ions and carbonate radicals in KHCO3 crystals: EPR and electron spin echo studies

NASA Astrophysics Data System (ADS)

Hoffmann, Stanislaw K.; Goslar, Janina; Lijewski, Stefan

2012-08-01

EPR studies of Cu2+ and two free radicals formed by γ-radiation were performed for KHCO3 single crystal at room temperature. From the rotational EPR results we concluded that Cu2+ is chelated by two carbonate molecules in a square planar configuration with spin-Hamiltonian parameters g|| = 2.2349 and A|| = 18.2 mT. Free radicals were identified as neutral HOCOrad with unpaired electron localized on the carbon atom and a radical anion CO3·- with unpaired electron localized on two oxygen atoms. The hyperfine splitting of the EPR lines by an interaction with a single hydrogen atom of HOCOrad was observed with isotropic coupling constants ao = 0.31 mT. Two differently oriented radical sites were identified in the crystal unit cell. Electron spin-lattice relaxation measured by electron spin echo methods shows that both Cu2+ and free radicals relax via two-phonon Raman processes with almost the same relaxation rate. The temperature dependence of the relaxation rate 1/T1 is well described with the effective Debye temperature ΘD = 175 K obtained from a fit to the Debye-type phonon spectrum. We calculated a more realistic Debye temperature value from available elastic constant values of the crystal as ΘD = 246 K. This ΘD-value and the Debye phonon spectrum approximation give a much worse fit to the experimental results. Possible contributions from a local mode or an optical mode are considered and it is suggested that the real phonon spectrum should be used for the relaxation data interpretation. It is unusual that free radicals in KHCO3 relax similarly to the well localized Cu2+ ions, which suggests a small destruction of the host crystal lattice by the ionizing irradiation allowing well coupling between radical and lattice dynamics.

Vector Beam Polarization State Spectrum Analyzer.

PubMed

Moreno, Ignacio; Davis, Jeffrey A; Badham, Katherine; Sánchez-López, María M; Holland, Joseph E; Cottrell, Don M

2017-05-22

We present a proof of concept for a vector beam polarization state spectrum analyzer based on the combination of a polarization diffraction grating (PDG) and an encoded harmonic q-plate grating (QPG). As a result, a two-dimensional polarization diffraction grating is formed that generates six different q-plate channels with topological charges from -3 to +3 in the horizontal direction, and each is split in the vertical direction into the six polarization channels at the cardinal points of the corresponding higher-order Poincaré sphere. Consequently, 36 different channels are generated in parallel. This special polarization diffractive element is experimentally demonstrated using a single phase-only spatial light modulator in a reflective optical architecture. Finally, we show that this system can be used as a vector beam polarization state spectrum analyzer, where both the topological charge and the state of polarization of an input vector beam can be simultaneously determined in a single experiment. We expect that these results would be useful for applications in optical communications.

The millimeter wave spectrum of methyl cyanate: a laboratory study and astronomical search in space^.

PubMed

Kolesniková, L; Alonso, J L; Bermúdez, C; Alonso, E R; Tercero, B; Cernicharo, J; Guillemin, J-C

2016-07-01

The recent discovery of methyl isocyanate (CH 3 NCO) in Sgr B2(N) and Orion KL makes methyl cyanate (CH 3 OCN) a potential molecule in the interstellar medium. The aim of this work is to fulfill the first requirement for its unequivocal identification in space, i.e. the availability of transition frequencies with high accuracy. The room-temperature rotational spectrum of methyl cyanate was recorded in the millimeter wave domain from 130 to 350 GHz. All rotational transitions revealed A - E splitting owing to methyl internal rotation and were globally analyzed using the ERHAM program. The data set for the ground torsional state of methyl cyanate exceeds 700 transitions within J″ = 10 - 35 and [Formula: see text] and newly derived spectroscopic constants reproduce the spectrum close to the experimental uncertainty. Spectral features of methyl cyanate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of methyl cyanate are provided.

On the Effective Mass of the Electron Neutrino in Beta Decay

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

Farzan, Yasaman

2002-12-20

In the presence of mixing between massive neutrino states, the distortion of the electron spectrum in beta decay is, in general, a function of several masses and mixing angles. For 3{nu}-schemes which describe the solar and atmospheric neutrino data, this distortion can be described by a single effective mass, under certain conditions. In the literature, two different definitions for the effective mass have been suggested. We show that for quasi-degenerate mass schemes (with an overall mass scale m and splitting {Delta}m{sup 2}) the two definitions coincide up to ({Delta}m{sup 2}){sup 2}/m{sup 4} corrections. We consider the impact of different effectivemore » masses on the integral energy spectrum. We show that the spectrum with a single mass can be used also to fit the data in the case of 4{nu}-schemes motivated, in particular, by the LSND results. In this case the accuracy of the mass determination turns out to be better than (10-15)%.« less

Influence of Stationary Crossflow Modulation on Secondary Instability

NASA Technical Reports Server (NTRS)

Choudhari, Meelan M.; Li, Fei; Paredes, Pedro

2016-01-01

A likely scenario for swept wing transition on subsonic aircraft with natural laminar flow involves the breakdown of stationary crossflow vortices via high frequency secondary instability. A majority of the prior research on this secondary instability has focused on crossflow vortices with a single dominant spanwise wavelength. This paper investigates the effects of the spanwise modulation of stationary crossflow vortices at a specified wavelength by a subharmonic stationary mode. Secondary instability of the modulated crossflow pattern is studied using planar, partial-differential-equation based eigenvalue analysis. Computations reveal that weak modulation by the first subharmonic of the input stationary mode leads to mode splitting that is particularly obvious for Y-type secondary modes that are driven by the wall-normal shear of the basic state. Thus, for each Y mode corresponding to the fundamental wavelength of results in unmodulated train of crossflow vortices, the modulated flow supports a pair of secondary modes with somewhat different amplification rates. The mode splitting phenomenon suggests that a more complex stationary modulation such as that induced by natural surface roughness would yield a considerably richer spectrum of secondary instability modes. Even modest levels of subharmonic modulation are shown to have a strong effect on the overall amplification of secondary disturbances, particularly the Z-modes driven by the spanwise shear of the basic state. Preliminary computations related to the nonlinear breakdown of these secondary disturbances provide interesting insights into the process of crossflow transition in the presence of the first subharmonic of the dominant stationary vortex.

Oxygen related recombination defects in Ta{sub 3}N{sub 5} water splitting photoanode

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

Fu, Gao; Yu, Tao, E-mail: yscfei@nju.edu.cn, E-mail: yutao@nju.edu.cn; Zou, Zhigang

2015-10-26

A key route to improving the performance of Ta{sub 3}N{sub 5} photoelectrochemical film devices in solar driving water splitting to hydrogen is to understand the nature of the serious recombination of photo-generated carriers. Here, by using the temperature-dependent photoluminescence (PL) spectrum, we confirmed that for the Ta{sub 3}N{sub 5} films prepared by nitriding Ta{sub 2}O{sub 5} precursor, one PL peak at 561 nm originates from deep-level defects recombination of the oxygen-enriched Ta{sub 3}N{sub 5} phases, and another one at 580 nm can be assigned to band recombination of Ta{sub 3}N{sub 5} itself. Both of the two bulk recombination processes may decrease themore » photoelectrochemical performance of Ta{sub 3}N{sub 5}. It was difficult to remove the oxygen-enriched impurities in Ta{sub 3}N{sub 5} films by increasing the nitriding temperatures due to their high thermodynamically stability. In addition, a broadening PL peak between 600 and 850 nm resulting from oxygen related surface defects was observed by the low-temperature PL measurement, which may induce the surface recombination of photo-generated carriers and can be removed by increasing the nitridation temperature. Our results provided direct experimental evidence to understand the effect of oxygen-related crystal defects in Ta{sub 3}N{sub 5} films on its photoelectric performance.« less

Spectral Characteristics of the Unitary Critical Almost-Mathieu Operator

NASA Astrophysics Data System (ADS)

Fillman, Jake; Ong, Darren C.; Zhang, Zhenghe

2017-04-01

We discuss spectral characteristics of a one-dimensional quantum walk whose coins are distributed quasi-periodically. The unitary update rule of this quantum walk shares many spectral characteristics with the critical Almost-Mathieu Operator; however, it possesses a feature not present in the Almost-Mathieu Operator, namely singularity of the associated cocycles (this feature is, however, present in the so-called Extended Harper's Model). We show that this operator has empty absolutely continuous spectrum and that the Lyapunov exponent vanishes on the spectrum; hence, this model exhibits Cantor spectrum of zero Lebesgue measure for all irrational frequencies and arbitrary phase, which in physics is known as Hofstadter's butterfly. In fact, we will show something stronger, namely, that all spectral parameters in the spectrum are of critical type, in the language of Avila's global theory of analytic quasiperiodic cocycles. We further prove that it has empty point spectrum for each irrational frequency and away from a frequency-dependent set of phases having Lebesgue measure zero. The key ingredients in our proofs are an adaptation of Avila's Global Theory to the present setting, self-duality via the Fourier transform, and a Johnson-type theorem for singular dynamically defined CMV matrices which characterizes their spectra as the set of spectral parameters at which the associated cocycles fail to admit a dominated splitting.

The millimeter and submillimeter rotational spectrum of the MgCN radical (X (sup 2) Sigma(+))

NASA Technical Reports Server (NTRS)

Anderson, M. A.; Steimle, T. C.; Ziurys, L. M.

1994-01-01

The pure rotational spectrum of the MgCN radical has been recorded in the laboratory using millimeter/submillimeter direct absorption spectroscopy. Twenty-seven rotational transitions of the species were observed in the range 101-376 GHz and indicate that the molecule is linear with a (sup 2)Sigma(+) ground electronic state, as predicted by theory. Spin rotation interactions were resolved in the spectra, but no hyperfine splittings were observed, which would originate with the nitrogen nuclear spin. The rotational and fine-structure constants were determined for this radical from a nonlinear least-squares fit to the data using a (sup 2)Sigma Hamiltonian. MgCN is of astrophysical interest because it is the metastable isomer of MgNC, which recently has been detected toward IRC +10216

Rotational spectrum of 1,1-difluoroethane-argon: influence of the interaction with the Ar atom on the V 3 barrier to internal rotation of the methyl group

NASA Astrophysics Data System (ADS)

Velino, Biagio; Melandri, Sonia; Favero, Paolo G.; Dell'Erba, Adele; Caminati, Walther

2000-01-01

The free-jet millimeter-wave absorption spectrum of 1,1-difluoroethane-Ar is reported. Most of the measured lines are split due to internal rotation of the methyl group and the tunnelling motion of Ar connecting two equivalent potential energy minima. The Ar atom, close to the CHF 2 group, eclipses one of the methylic hydrogens in the symmetryless geometry of the complex, reducing in this way the barrier to the internal rotation of the methyl group with respect to isolated 1,1-difluoroethane. For high J levels the distance of Ar from the molecule increases, however, due to the centrifugal distortion, and the barrier increases towards the value for 1,1-difluoroethane.

Brief Report: A Gaming Approach to the Assessment of Attention Networks in Autism Spectrum Disorder and Typical Development.

PubMed

Mash, Lisa E; Klein, Raymond M; Townsend, Jeanne

2018-06-12

Attentional impairments are among the earliest identifiable features of autism spectrum disorders (ASDs). Three attention networks have been extensively studied using the attention network test (ANT), but this long and repetitive task may pose challenges for individuals with ASDs. The AttentionTrip was developed as a more engaging measure of attention network efficiency. In 20 adults with ASDs and 20 typically developing controls, both tasks produced typical network scores (all p < .003, all Cohen's d > 0.78). Reaction time was less variable in the AttentionTrip than the ANT, possibly reflecting improved task engagement. Although the AttentionTrip elicited more consistent responses throughout an experimental session, anomalously low split-half reliability for its executive control network suggests that some changes may be needed.

Birefringent breakup of Dirac fermions on a square optical lattice

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

Kennett, Malcolm P.; Komeilizadeh, Nazanin; Kaveh, Kamran

2011-05-15

We introduce a lattice model for fermions in a spatially periodic magnetic field that also has spatially periodic hopping amplitudes. We discuss how this model might be realized with cold atoms in an artificial magnetic field on a square optical lattice. When there is an average flux of half a flux quantum per plaquette, the spectrum of low-energy excitations can be described by massless Dirac fermions in which the usually doubly degenerate Dirac cones split into cones with different ''speeds of light.'' These gapless birefringent Dirac fermions arise because of broken chiral symmetry in the kinetic energy term of themore » effective low-energy Hamiltonian. We characterize the effects of various perturbations to the low-energy spectrum, including staggered potentials, interactions, and domain-wall topological defects.« less

Terahertz laser vibration-rotation-tunneling spectrum of the water pentamer-d 10. . Constraints on the bifurcation tunneling dynamics

NASA Astrophysics Data System (ADS)

Cruzan, Jeff D.; Viant, Mark R.; Brown, Mac G.; Lucas, Don D.; Liu, Kun; Saykally, Richard J.

1998-08-01

The vibration-rotation-tunneling (VRT) spectrum of a low-frequency intermolecular vibration of (D 2O) 5 was recorded near 0.9 THz (30.2 cm -1). From an analysis of the relative intensities in the compact Q-branch region, the ground-state C-rotational constant is estimated to be 975±60 MHz, consistent with ab initio structural predictions. The precisely determined B-rotational constant ( B=1750.96±0.20 MHz) agrees well with previous results. Efforts to resolve possible bifurcation tunneling fine structure, such as that observed in VRT spectra of (D 2O) 3, revealed no such effects. This constrains the splittings to be less than 450 kHz, or roughly 3 times smaller than required by previous results.

A methodology for double patterning compliant split and design

NASA Astrophysics Data System (ADS)

Wiaux, Vincent; Verhaegen, Staf; Iwamoto, Fumio; Maenhoudt, Mireille; Matsuda, Takashi; Postnikov, Sergei; Vandenberghe, Geert

2008-11-01

Double Patterning allows to further extend the use of water immersion lithography at its maximum numerical aperture NA=1.35. Splitting of design layers to recombine through Double Patterning (DP) enables an effective resolution enhancement. Single polygons may need to be split up (cut) depending on the pattern density and its 2D content. The split polygons recombine at the so-called 'stitching points'. These stitching points may affect the yield due to the sensitivity to process variations. We describe a methodology to ensure a robust double patterning by identifying proper split- and design- guidelines. Using simulations and experimental data, we discuss in particular metal1 first interconnect layers of random LOGIC and DRAM applications at 45nm half-pitch (hp) and 32nm hp where DP may become the only timely patterning solution.

New laboratory atomic data for neutral, singly and doubly ionised iron group elements for astrophysics applications

NASA Astrophysics Data System (ADS)

Pickering, Juliet C.; Nave, Gillian; Liggins, Florence; Clear, Christian; Ruffoni, Matthew; Sansonetti, Craig

2015-08-01

We present new laboratory spectroscopic measurements to produce atomic data for astrophysically important species: neutral, singly and doubly ionised iron group elements.We use high resolution Fourier Transform Spectrometry (FTS) (resolving power up to 2x106 at 200nm) to measure atomic spectra, giving accurate line wavelengths (to a few parts in 108), atomic energy levels, hyperfine structure splitting and log gfs (accurate to a few %) (Ruffoni et al this meeting). These data are vital for astrophysical spectral analyses for: line identification, spectrum synthesis, elemental abundance determinations [eg 1], and disentangling of blends etc. It is not possible to theoretically calculate these atomic data to the accuracy needed for modern astrophysics applications.At Imperial College we have a unique visible-VUV FT spectrometer with short wavelength cut-off of 135nm. We supplement FTS data at shorter wavelengths with spectra recorded on the NIST 10.7m grating spectrograph (with phosphor image or photographic plates) and at longer wavelengths in the IR we use the NIST IR FT spectrometer.An elemental spectrum may contain thousands of spectral lines from the IR to VUV. We use these wavelengths to correct known atomic energy levels, and search for new atomic levels. The result is a classified linelist and accurate atomic energy levels.We present progress on iron group element atomic energy levels and wavelengths for V I and V II [2,3], Co III [4], Cr I, Mn I and Mn II, and Ni II.This work is supported by STFC(UK), The Leverhulme Trust, The Royal Society and NASA.References[1] Bergemann M, Pickering JC & Gehren T,“NLTE analysis of Co I/Co II lines in spectra of cool stars with new laboratory hyperfine splitting constants",MNRAS 401(2) 1334 (2010)[2] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V II”, ApJS 207,13 (2013)[3] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V I",ApJS 192,11 (2011)[4] Smillie DG, Pickering JC, Nave G & Smith PL,“The Spectrum and Term Analysis of Co III Measured using Fourier Transform and Grating Spectroscopy”,ApJS submitted

Application of particle splitting method for both hydrostatic and hydrodynamic cases in SPH

NASA Astrophysics Data System (ADS)

Liu, W. T.; Sun, P. N.; Ming, F. R.; Zhang, A. M.

2018-01-01

Smoothed particle hydrodynamics (SPH) method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid-solid interaction problems. However, in most simulations, uniform particle distributions are used and the multi-resolution, which can obviously improve the local accuracy and the overall computational efficiency, has seldom been applied. In this paper, a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems. The splitting algorithm is that, when a coarse (mother) particle enters the splitting region, it will be split into four daughter particles, which inherit the physical parameters of the mother particle. In the particle splitting process, conservations of mass, momentum and energy are ensured. Based on the error analysis, the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases. Finally, the scheme is validated by five basic cases, which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic problems.

Tablet splitting: a review of the clinical and economic outcomes and patient acceptance. Second of a 2-part series. Part 1 was published in May 2012 (Consult Pharm 2012;27:239-53).

PubMed

Freeman, Maisha Kelly; White, Whitney; Iranikhah, Maryam

2012-06-01

To describe the clinical outcomes, patient acceptance, and economic effect associated with tablet splitting. PubMed (1966-June 2011) and International Pharmaceutical Abstract (1975-June 2011) searches were conducted using tablet splitting as the search terms. All studies that evaluated the clinical outcome (n = 4), patient acceptance (n = 5), and economic effects (n = 8) of tablet splitting were included. The American Pharmacists Association guidelines, recommendations from the Food and Drug Administration, and clinical trial data were evaluated. The majority of trials conducted evaluating clinical outcomes associated with tablet splitting were evaluated in patients receiving statins and antihypertensives. Clinical outcomes associated with risperidone were assessed. No adverse clinical outcomes were observed with therapy. Most studies evaluating the economic effects of tablet splitting have revealed a cost savings associated with this process; however, many studies were subject to limitations. The first part of this two-part series reviewed the weight and content uniformity in tablet splitting. Tablet splitting does not seem to significantly affect clinical outcomes related to management of hypertension, cholesterol, or psychiatric disorders, nor influence overall patient adherence.

Isoscalar-isovector mass splittings in excited mesons

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

Geiger, P.

1994-06-01

Mass splittings between the isovector and isoscalar members of meson nonets arise in part from hadronic loop diagrams which violate the Okubo-Zweig-Iizuka rule. Using a model for these loop processes which works qualitatively well in the established nonets, I tabulate predictions for the splittings and associated isoscalar mixing angles in the remaining nonets below about 2 GeV, and explain some of their systematic features. The model predicts significant deviations from ideal mixing in the excited vector nonets.

Angular-split/temporal-delay approach to ultrafast protein dynamics at XFELs.

PubMed

Ren, Zhong; Yang, Xiaojing

2016-07-01

X-ray crystallography promises direct insights into electron-density changes that lead to and arise from structural changes such as electron and proton transfer and the formation, rupture and isomerization of chemical bonds. The ultrashort pulses of hard X-rays produced by free-electron lasers present an exciting opportunity for capturing ultrafast structural events in biological macromolecules within femtoseconds after photoexcitation. However, shot-to-shot fluctuations, which are inherent to the very process of self-amplified spontaneous emission (SASE) that generates the ultrashort X-ray pulses, are a major source of noise that may conceal signals from structural changes. Here, a new approach is proposed to angularly split a single SASE pulse and to produce a temporal delay of picoseconds between the split pulses. These split pulses will allow the probing of two distinct states before and after photoexcitation triggered by a laser pulse between the split X-ray pulses. The split pulses originate from a single SASE pulse and share many common properties; thus, noise arising from shot-to-shot fluctuations is self-canceling. The unambiguous interpretation of ultrafast structural changes would require diffraction data at atomic resolution, as these changes may or may not involve any atomic displacement. This approach, in combination with the strategy of serial crystallography, offers a solution to study ultrafast dynamics of light-initiated biochemical reactions or biological processes at atomic resolution.

Shrinking plastic tubing and nonstandard diameters

NASA Technical Reports Server (NTRS)

Ruiz, W. V.; Thatcher, C. S.

1980-01-01

Process allows larger-than-normal postshrink diameters without splitting. Tetrafluoroethylene tubing on mandrel is supported within hot steel pipe by several small diameter coil sections. Rising temperature of mandrel is measured via thermocouple so assembly can be removed without overshrinking (and splitting) of tubing.

Noninvasive hemoglobin measurement using dynamic spectrum

NASA Astrophysics Data System (ADS)

Yi, Xiaoqing; Li, Gang; Lin, Ling

2017-08-01

Spectroscopy methods for noninvasive hemoglobin (Hgb) measurement are interfered by individual difference and particular weak signal. In order to address these problems, we have put forward a series of improvement methods based on dynamic spectrum (DS), including instrument design, spectrum extraction algorithm, and modeling approach. The instrument adopts light sources composed of eight laser diodes with the wavelength range from 600 nm to 1100 nm and records photoplethysmography signals at eight wavelengths synchronously. In order to simplify the optical design, we modulate the light sources with orthogonal square waves and design the corresponding demodulation algorithm, instead of adopting a beam-splitting system. A newly designed algorithm named difference accumulation has been proved to be effective in improving the accuracy of dynamic spectrum extraction. 220 subjects are involved in the clinical experiment. An extreme learning machine calibration model between the DS data and the Hgb levels is established. Correlation coefficient and root-mean-square error of prediction sets are 0.8645 and 8.48 g/l, respectively. The results indicate that the Hgb level can be derived by this approach noninvasively with acceptable precision and accuracy. It is expected to achieve a clinic application in the future.

Photoelectron Spectroscopy Study of Quinonimides

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

Hossain, Ekram; Deng, Shihu M.; Gozem, Samer

Structures and energetics of o-, m- and p-quinonimide anions (OC6H4N) and quinoniminyl radicals have been investigated by using negative ion photoelectron spectroscopy. Modeling of the photoelectron spectrum of the ortho isomer shows that the ground state of the anion is a triplet, while the quinoniminyl radical has a doublet ground state with a doublet-quartet splitting of 35.5 kcal/mol. The para radical has doublet ground state, but a band for a quartet state is missing from the photoelectron spectrum indicating that the anion has a singlet ground state, in contrast to previously reported calculations. The theoretical modeling is revisited here, andmore » it is shown that accurate predictions for the electronic structure of the para quinonimide anion require both an accurate account of electron correlation and a sufficiently diffuse basis set. Electron affinities of o- and p-quinoniminyl radicals are measured to be 1.715 ± 0.010 and 1.675 ± 0.010 eV, respectively. The photoelectron spectrum of the m-quinonimide anion shows that the ion undergoes several different rearrangements, including a rearrangement to the energetically favorable para isomer. Such rearrangements preclude a meaningful analysis of the experimental spectrum.« less

The spectra of rectangular lattices of quantum waveguides

NASA Astrophysics Data System (ADS)

Nazarov, S. A.

2017-02-01

We obtain asymptotic formulae for the spectral segments of a thin (h\\ll 1) rectangular lattice of quantum waveguides which is described by a Dirichlet problem for the Laplacian. We establish that the structure of the spectrum of the lattice is incorrectly described by the commonly accepted quantum graph model with the traditional Kirchhoff conditions at the vertices. It turns out that the lengths of the spectral segments are infinitesimals of order O(e-δ/h), δ> 0, and O(h) as h\\to+0, and gaps of width O(h-2) and O(1) arise between them in the low- frequency and middle- frequency spectral ranges respectively. The first spectral segment is generated by the (unique) eigenvalue in the discrete spectrum of an infinite cross-shaped waveguide \\Theta. The absence of bounded solutions of the problem in \\Theta at the threshold frequency means that the correct model of the lattice is a graph with Dirichlet conditions at the vertices which splits into two infinite subsets of identical edges- intervals. By using perturbations of finitely many joints, we construct any given number of discrete spectrum points of the lattice below the essential spectrum as well as inside the gaps.

VizieR Online Data Catalog: Sgr B2(N) and Sgr B2(M) IRAM 30m line survey (Belloche+, 2013)

NASA Astrophysics Data System (ADS)

Belloche, A.; Mueller, H. S. P.; Menten, K. M.; Schilke, P.; Comito, C.

2013-08-01

The list of line identifications corresponding to the blue labels in Figs. 2 to 7 where the labels are often too crowded to be easily readable are available in ASCII format. The lists are split into six files, three for Sgr B2(N) and three for Sgr B2(M). For each source, there is one file per atmospheric window (3, 2, and 1mm). Each file is ordered by increasing frequency. The observed and synthetic spectra of Sgr B2(N) and Sgr B2(M) between 80 and 116GHz are available both in ASCII and FITS formats. The synthetic spectra were resampled to the same frequency channels as the observed spectra. The blanking value is -1000K for the ASCII files. There is one ASCII file per source. There are two FITS files per source, one for the observed spectrum and one for the synthetic spectrum. The intensities are in main-beam temperature scale in K. The blanking value is 42.75234K for the observed spectrum of SgrB2(N) and 53.96533K for the observed spectrum of SgrB2(M). (9 data files).

A multiple-time-scale turbulence model based on variable partitioning of turbulent kinetic energy spectrum

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Chen, C.-P.

1987-01-01

A multiple-time-scale turbulence model of a single point closure and a simplified split-spectrum method is presented. In the model, the effect of the ratio of the production rate to the dissipation rate on eddy viscosity is modeled by use of the multiple-time-scales and a variable partitioning of the turbulent kinetic energy spectrum. The concept of a variable partitioning of the turbulent kinetic energy spectrum and the rest of the model details are based on the previously reported algebraic stress turbulence model. Example problems considered include: a fully developed channel flow, a plane jet exhausting into a moving stream, a wall jet flow, and a weakly coupled wake-boundary layer interaction flow. The computational results compared favorably with those obtained by using the algebraic stress turbulence model as well as experimental data. The present turbulence model, as well as the algebraic stress turbulence model, yielded significantly improved computational results for the complex turbulent boundary layer flows, such as the wall jet flow and the wake boundary layer interaction flow, compared with available computational results obtained by using the standard kappa-epsilon turbulence model.

A multiple-time-scale turbulence model based on variable partitioning of the turbulent kinetic energy spectrum

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Chen, C.-P.

1989-01-01

A multiple-time-scale turbulence model of a single point closure and a simplified split-spectrum method is presented. In the model, the effect of the ratio of the production rate to the dissipation rate on eddy viscosity is modeled by use of the multiple-time-scales and a variable partitioning of the turbulent kinetic energy spectrum. The concept of a variable partitioning of the turbulent kinetic energy spectrum and the rest of the model details are based on the previously reported algebraic stress turbulence model. Example problems considered include: a fully developed channel flow, a plane jet exhausting into a moving stream, a wall jet flow, and a weakly coupled wake-boundary layer interaction flow. The computational results compared favorably with those obtained by using the algebraic stress turbulence model as well as experimental data. The present turbulence model, as well as the algebraic stress turbulence model, yielded significantly improved computational results for the complex turbulent boundary layer flows, such as the wall jet flow and the wake boundary layer interaction flow, compared with available computational results obtained by using the standard kappa-epsilon turbulence model.

The Millimeter-Wave Spectrum of Propanal

NASA Astrophysics Data System (ADS)

Zingsheim, Oliver; Müller, Holger S. P.; Lewen, Frank; Schlemmer, Stephan

2017-06-01

The microwave spectrum of propanal, also known as propionaldehyde, CH_3CH_2CHO, has been investigated in the laboratory already since 1964^1 and has also been detected in space^2. Recently, propanal was detected with the Atacama Large Millimeter/submillimeter Array (ALMA), Protostellar Interferometric Line Survey (PILS)^3. The high sensitivity and resolution of ALMA indicated small discrepancies between observed and predicted rotational spectra of propanal. As higher accuracies are desired the spectrum of propanal was measured up to 500 GHz with the Cologne (Sub-)Millimeter spectrometer. Propanal has two stable conformers, syn and gauche, which differ mainly in the rotation of the aldehyd group with respect to the rigid C-atom framework of the molecule. We extensively studied both of them. The lower syn-conformer shows small splittings caused by the internal rotation of the methyl group, whereas the spectrum of gauche-propanal is complicated due to the tunneling rotation interaction from two stable degenerate conformers. Additionally, we analyzed vibrationally excited states. ^1 Butcher et al., J. Chem. Phys. 40 6 (1964) ^2 Hollis et al., Astrophys. J. 610 L21 (2004) ^3 Lykke et al., A&A 597 A53 (2017)

Analysis of the S{sub 2}←S{sub 0} vibronic spectrum of the ortho-cyanophenol dimer using a multimode vibronic coupling approach

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

Kopec, Sabine; Köppel, Horst; Ottiger, Philipp

2015-02-28

The S{sub 2}←S{sub 0} vibronic spectrum of the ortho-cyanophenol dimer (oCP){sub 2} is analyzed in a joint experimental and theoretical investigation. Vibronic excitation energies up to 750 cm{sup −1} are covered, which extends our previous analysis of the quenching of the excitonic splitting in this and related species [Kopec et al., J. Chem. Phys. 137, 184312 (2012)]. As we demonstrate, this necessitates an extension of the coupling model. Accordingly, we compute the potential energy surfaces of the ortho-cyanophenol dimer (oCP){sub 2} along all relevant normal modes using the approximate second-order coupled cluster method RI-CC2 and extract the corresponding coupling constantsmore » using the linear and quadratic vibronic coupling scheme. These serve as the basis to calculate the vibronic spectrum. The theoretical results are found to be in good agreement with the experimental highly resolved resonant two-photon ionization spectrum. This allows to interpret key features of the excitonic and vibronic interactions in terms of nodal patterns of the underlying vibronic wave functions.« less

Rydberg State Stark Spectroscopy and Applications to Plasma Diagnostics

DTIC Science & Technology

1990-03-01

Bayfield47 provides an excellent review of the AC Stark effect, in which the primary effect is Rabi splitting. Several authors48 , 49, 50 have...purity of the spectrum indicates that the field present is dominantly anisotropic . 53 n:26NEON LINE n=35 0 n= 40 p.- n=45 IL 0 31975 31950 31925 31900...applied (axial) electric field which is anisotropic , so pure polarization spectra can be recorded. The intensity profile of the Am = 0 polarization is

Microwave spectrum, structure, dipole moment, and Coriolis coupling of 1,1-difluoroallene

NASA Technical Reports Server (NTRS)

Durig, J. R.; Li, Y. S.; Tong, C. C.; Zens, A. P.; Ellis, P. D.

1974-01-01

Microwave spectra from 12.4 to 40.0 GHz were recorded for five isotopic species of 1,1-difluoroallene. A-type transitions were observed and R-branch assignments were made for the ground state and two vibrationally excited states. Several structural parameters of the compounds were determined. The dipole moment value obtained from Stark splitting was 2.07 plus or minus 0.03 D. A Coriolis coupling was observed between the two-low-frequency C = C = C bending modes.

A non-isotropic multiple-scale turbulence model

NASA Technical Reports Server (NTRS)

Chen, C. P.

1990-01-01

A newly developed non-isotropic multiple scale turbulence model (MS/ASM) is described for complex flow calculations. This model focuses on the direct modeling of Reynolds stresses and utilizes split-spectrum concepts for modeling multiple scale effects in turbulence. Validation studies on free shear flows, rotating flows and recirculating flows show that the current model perform significantly better than the single scale k-epsilon model. The present model is relatively inexpensive in terms of CPU time which makes it suitable for broad engineering flow applications.

Quantifying Hydrogen Bond Cooperativity in Water: VRT Spectroscopy of the Water Tetramer

NASA Astrophysics Data System (ADS)

Cruzan, J. D.; Braly, L. B.; Liu, Kun; Brown, M. G.; Loeser, J. G.; Saykally, R. J.

1996-01-01

Measurement of the far-infrared vibration-rotation tunneling spectrum of the perdeuterated water tetramer is described. Precisely determined rotational constants and relative intensity measurements indicate a cyclic quasi-planar minimum energy structure, which is in agreement with recent ab initio calculations. The O-O separation deduced from the data indicates a rapid exponential convergence to the ordered bulk value with increasing cluster size. Observed quantum tunneling splittings are interpreted in terms of hydrogen bond rearrangements connecting two degenerate structures.

Dispersive Phase in the L-band InSAR Image Associated with Heavy Rain Episodes

NASA Astrophysics Data System (ADS)

Furuya, M.; Kinoshita, Y.

2017-12-01

Interferometric synthetic aperture radar (InSAR) is a powerful geodetic technique that allows us to detect ground displacements with unprecedented spatial resolution, and has been used to detect displacements due to earthquakes, volcanic eruptions, and glacier motion. In the meantime, due to the microwave propagation through ionosphere and troposphere, we often encounter non-negligible phase anomaly in InSAR data. Correcting for the ionsphere and troposphere is therefore a long-standing issue for high-precision geodetic measurements. However, if ground displacements are negligible, InSAR image can tell us the details of the atmosphere.Kinoshita and Furuya (2017, SOLA) detected phase anomaly in ALOS/PALSAR InSAR data associated with heavy rain over Niigata area, Japan, and performed numerical weathr model simulation to reproduce the anomaly; ALOS/PALSAR is a satellite-based L-band SAR sensor launched by JAXA in 2006 and terminated in 2011. The phase anomaly could be largely reproduced, using the output data from the weather model. However, we should note that numerical weather model outputs can only account for the non-dispersive effect in the phase anomaly. In case of severe weather event, we may expect dispersive effect that could be caused by the presence of free-electrons.In Global Navigation Satellite System (GNSS) positioning, dual frequency measurements allow us to separate the ionospheric dispersive component from tropospheric non-dispersive components. In contrast, SAR imaging is based on a single carrier frequency, and thus no operational ionospheric corrections have been performed in InSAR data analyses. Recently, Gomba et al (2016) detailed the processing strategy of split spectrum method (SSM) for InSAR, which splits the finite bandwidth of the range spectrum and virtually allows for dual-frequency measurements.We apply the L-band InSAR SSM to the heavy rain episodes, in which more than 50 mm/hour precipitations were reported. We report the presence of phase anomaly in both dispersive and non-dispersive components. While the original phase anomaly turns out to be mostly due to the non-dispersive effect, we could recognize local anomalies in the dispersive component as well. We will discuss its geophysical implications, and may show several case studies.

All solution-processed lead halide perovskite-BiVO4 tandem assembly for photolytic solar fuels production.

PubMed

Chen, Yong-Siou; Manser, Joseph S; Kamat, Prashant V

2015-01-21

The quest for economic, large-scale hydrogen production has motivated the search for new materials and device designs capable of splitting water using only energy from the sun. Here we introduce an all solution-processed tandem water splitting assembly composed of a BiVO4 photoanode and a single-junction CH3NH3PbI3 hybrid perovskite solar cell. This unique configuration allows efficient solar photon management, with the metal oxide photoanode selectively harvesting high energy visible photons, and the underlying perovskite solar cell capturing lower energy visible-near IR wavelengths in a single-pass excitation. Operating without external bias under standard AM 1.5G illumination, the photoanode-photovoltaic architecture, in conjunction with an earth-abundant cobalt phosphate catalyst, exhibits a solar-to-hydrogen conversion efficiency of 2.5% at neutral pH. The design of low-cost tandem water splitting assemblies employing single-junction hybrid perovskite materials establishes a potentially promising new frontier for solar water splitting research.

Facile formation of 2D Co2P@Co3O4 microsheets through in-situ toptactic conversion and surface corrosion: Bifunctional electrocatalysts towards overall water splitting

NASA Astrophysics Data System (ADS)

Yao, Lihua; Zhang, Nan; Wang, Yin; Ni, Yuanman; Yan, Dongpeng; Hu, Changwen

2018-01-01

Exploring efficient non-precious electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for many renewable energy conversion processes. In this work, we report that 2D Co2P@Co3O4 microsheets can be prepared through an in-situ toptactic conversion from single-crystal β-Co(OH)2 microplatelets, associated with a surface phosphatization and corrosion process. The resultant Co2P@Co3O4 2D hybrid materials can further serve as self-supported bifunctional catalytic electrodes to drive the overall water splitting for HER and OER simultaneously, with low overpotentials and high long-term stability. Furthermore, a water electrolyzer based on Co2P@Co3O4 hybrid as both anode and cathode is fabricated, which achieves 10 mA cm-2 current at only 1.57 V during water splitting process. Therefore, this work provides a facile strategy to obtain 2D Co2P-based micro/nanostructures, which act as low-cost and highly active electrocatalysts towards overall water splitting application.

Dopant profile modeling by rare event enhanced domain-following molecular dynamics

DOEpatents

Beardmore, Keith M.; Jensen, Niels G.

2002-01-01

A computer-implemented molecular dynamics-based process simulates a distribution of ions implanted in a semiconductor substrate. The properties of the semiconductor substrate and ion dose to be simulated are first initialized, including an initial set of splitting depths that contain an equal number of virtual ions implanted in each substrate volume determined by the splitting depths. A first ion with selected velocity is input onto an impact position of the substrate that defines a first domain for the first ion during a first timestep, where the first domain includes only those atoms of the substrate that exert a force on the ion. A first position and velocity of the first ion is determined after the first timestep and a second domain of the first ion is formed at the first position. The first ion is split into first and second virtual ions if the first ion has passed through a splitting interval. The process then follows each virtual ion until all of the virtual ions have come to rest. A new ion is input to the surface and the process repeats until all of the ion dose has been input. The resulting ion rest positions form the simulated implant distribution.

Closed-Loop Acoustic Control of Reverberant Room for Satellite Environmental Testing

NASA Astrophysics Data System (ADS)

Janssens, Karl; Bianciardi, Fabio; Sabbatini, Danilo; Debille, Jan; Carrella, Alex

2012-07-01

The full satellite acoustic test is an important milestone in a satellite launch survivability verification campaign. This test is required to verify the satellite’s mechanical design against the high-level acoustic loads induced by the launch vehicle during the atmospheric flight. During the test, the satellite is subjected to a broadband diffuse acoustic field, reproducing the pressure levels observed during launch. The excitation is in most cases provided by a combination of horns for the low frequencies and noise generators for the higher frequencies. Acoustic control tests are commonly performed in reverberant rooms, controlling the sound pressure levels in third octave bands over the specified target spectrum. This paper discusses an automatic feedback control system for acoustic control of large reverberation rooms for satellite environmental testing. The acoustic control system consists of parallel third octave PI (Proportional Integral) feedback controllers that take the reverberation characteristics of the room into consideration. The drive output of the control system is shaped at every control step based on the comparison of the average third octave noise spectrum, measured from a number of microphones in the test room, with the target spectrum. Cross-over filters split the output drive into band- limited signals to feed each of the horns. The control system is realized in several steps. In the first phase, a dynamic process model is developed, including the non-linear characteristics of the horns and the reverberant properties of the room. The model is identified from dynamic experiments using system identification techniques. In the next phase, an adequate control strategy is designed which is capable of reaching the target spectrum in the required time period without overshoots. This control strategy is obtained from model-in-the-loop (MIL) simulations, evaluating the performance of various potential strategies. Finally, the proposed strategy is implemented in real-time and its control performance tested and validated.

ZnO/CuO/M (M = Ag, Au) Hierarchical Nanostructure by Successive Photoreduction Process for Solar Hydrogen Generation.

PubMed

Kwon, Jinhyeong; Cho, Hyunmin; Jung, Jinwook; Lee, Habeom; Hong, Sukjoon; Yeo, Junyeob; Han, Seungyong; Ko, Seung Hwan

2018-05-12

To date, solar energy generation devices have been widely studied to meet a clean and sustainable energy source. Among them, water splitting photoelectrochemical cell is regarded as a promising energy generation way for splitting water molecules and generating hydrogen by sunlight. While many nanostructured metal oxides are considered as a candidate, most of them have an improper bandgap structure lowering energy transition efficiency. Herein, we introduce a novel wet-based, successive photoreduction process that can improve charge transfer efficiency by surface plasmon effect for a solar-driven water splitting device. The proposed process enables to fabricate ZnO/CuO/Ag or ZnO/CuO/Au hierarchical nanostructure, having an enhanced electrical, optical, photoelectrochemical property. The fabricated hierarchical nanostructures are demonstrated as a photocathode in the photoelectrochemical cell and characterized by using various analytic tools.

ZnO/CuO/M (M = Ag, Au) Hierarchical Nanostructure by Successive Photoreduction Process for Solar Hydrogen Generation

PubMed Central

Kwon, Jinhyeong; Cho, Hyunmin; Jung, Jinwook; Lee, Habeom; Han, Seungyong

2018-01-01

To date, solar energy generation devices have been widely studied to meet a clean and sustainable energy source. Among them, water splitting photoelectrochemical cell is regarded as a promising energy generation way for splitting water molecules and generating hydrogen by sunlight. While many nanostructured metal oxides are considered as a candidate, most of them have an improper bandgap structure lowering energy transition efficiency. Herein, we introduce a novel wet-based, successive photoreduction process that can improve charge transfer efficiency by surface plasmon effect for a solar-driven water splitting device. The proposed process enables to fabricate ZnO/CuO/Ag or ZnO/CuO/Au hierarchical nanostructure, having an enhanced electrical, optical, photoelectrochemical property. The fabricated hierarchical nanostructures are demonstrated as a photocathode in the photoelectrochemical cell and characterized by using various analytic tools. PMID:29757225

Imaging nanobubble nucleation and hydrogen spillover during electrocatalytic water splitting.

PubMed

Hao, Rui; Fan, Yunshan; Howard, Marco D; Vaughan, Joshua C; Zhang, Bo

2018-06-05

Nucleation and growth of hydrogen nanobubbles are key initial steps in electrochemical water splitting. These processes remain largely unexplored due to a lack of proper tools to probe the nanobubble's interfacial structure with sufficient spatial and temporal resolution. We report the use of superresolution microscopy to image transient formation and growth of single hydrogen nanobubbles at the electrode/solution interface during electrocatalytic water splitting. We found hydrogen nanobubbles can be generated even at very early stages in water electrolysis, i.e., ∼500 mV before reaching its thermodynamic reduction potential. The ability to image single nanobubbles on an electrode enabled us to observe in real time the process of hydrogen spillover from ultrathin gold nanocatalysts supported on indium-tin oxide.

Black hole meiosis

NASA Astrophysics Data System (ADS)

van Herck, Walter; Wyder, Thomas

2010-04-01

The enumeration of BPS bound states in string theory needs refinement. Studying partition functions of particles made from D-branes wrapped on algebraic Calabi-Yau 3-folds, and classifying states using split attractor flow trees, we extend the method for computing a refined BPS index, [1]. For certain D-particles, a finite number of microstates, namely polar states, exclusively realized as bound states, determine an entire partition function (elliptic genus). This underlines their crucial importance: one might call them the ‘chromosomes’ of a D-particle or a black hole. As polar states also can be affected by our refinement, previous predictions on elliptic genera are modified. This can be metaphorically interpreted as ‘crossing-over in the meiosis of a D-particle’. Our results improve on [2], provide non-trivial evidence for a strong split attractor flow tree conjecture, and thus suggest that we indeed exhaust the BPS spectrum. In the D-brane description of a bound state, the necessity for refinement results from the fact that tachyonic strings split up constituent states into ‘generic’ and ‘special’ states. These are enumerated separately by topological invariants, which turn out to be partitions of Donaldson-Thomas invariants. As modular predictions provide a check on many of our results, we have compelling evidence that our computations are correct.

Inter-band optoelectronic properties in quantum dot structure of low band gap III-V semiconductors

NASA Astrophysics Data System (ADS)

Dey, Anup; Maiti, Biswajit; Chanda Sarkar, Debasree

2014-04-01

A generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k→) dependence of the optical transition matrix element. The band structures of these low band gap semiconducting materials with sufficiently separated split-off valance band are frequently described by the three energy band model of Kane. This has been adopted for analysis of the IOAC and MG taking InAs, InSb, Hg1-xCdxTe, and In1-xGaxAsyP1-y lattice matched to InP, as example of III-V compound semiconductors, having varied split-off energy band compared to their bulk band gap energy. It has been found that magnitude of the IOAC for quantum dots increases with increasing incident photon energy and the lines of absorption are more closely spaced in the three band model of Kane than those with parabolic energy band approximations reflecting the direct the influence of energy band parameters. The results show a significant deviation to the MG spectrum of narrow-gap materials having band nonparabolicity compared to the parabolic band model approximations. The results reflect the important role of valence band split-off energies in these narrow gap semiconductors.

Advances in Mössbauer data analysis

NASA Astrophysics Data System (ADS)

de Souza, Paulo A.

1998-08-01

The whole Mössbauer community generates a huge amount of data in several fields of human knowledge since the first publication of Rudolf Mössbauer. Interlaboratory measurements of the same substance may result in minor differences in the Mössbauer Parameters (MP) of isomer shift, quadrupole splitting and internal magnetic field. Therefore, a conventional data bank of published MP will be of limited help in identification of substances. Data bank search for exact information became incapable to differentiate the values of Mössbauer parameters within the experimental errors (e.g., IS = 0.22 mm/s from IS = 0.23 mm/s), but physically both values may be considered the same. An artificial neural network (ANN) is able to identify a substance and its crystalline structure from measured MP, and its slight variations do not represent an obstacle for the ANN identification. A barrier to the popularization of Mössbauer spectroscopy as an analytical technique is the absence of a full automated equipment, since the analysis of a Mössbauer spectrum normally is time-consuming and requires a specialist. In this work, the fitting process of a Mössbauer spectrum was completely automated through the use of genetic algorithms and fuzzy logic. Both software and hardware systems were implemented turning out to be a fully automated Mössbauer data analysis system. The developed system will be presented.

[Work organization of the Civic Hospital in Split during the Second World War (1941-1945)].

PubMed

Brisky, Livia

2011-01-01

In the first half of the 20th century, Civic Hospital in Split intensified its formation towards health institution in the modern sense. The need for competent physicians and specialized experts, heads of the individual hospital departments, also became in Split Hospital the part of the global process of disintegration of medicine into the direction of medical specializations. The aim of this study was to investigate the function of the Civic Hospital in Split during the Second World War on the basis of the archival sources preserved in the State Archives in Split. The work organization, the names of the physicians and detailed arrangements of hospital beds were presented, as well as the increase of its capacity during analyzed period.Great attention was also dedicated to the foundation of new hospital departments. This study revealed the development of the Civic Hospital in Split between 1941 and 1945 which could offer complete medical care to the sick and wounded persons.

Small-bubble transport and splitting dynamics in a symmetric bifurcation.

PubMed

Qamar, Adnan; Warnez, Matthew; Valassis, Doug T; Guetzko, Megan E; Bull, Joseph L

2017-08-01

Simulations of small bubbles traveling through symmetric bifurcations are conducted to garner information pertinent to gas embolotherapy, a potential cancer treatment. Gas embolotherapy procedures use intra-arterial bubbles to occlude tumor blood supply. As bubbles pass through bifurcations in the blood stream nonhomogeneous splitting and undesirable bioeffects may occur. To aid development of gas embolotherapy techniques, a volume of fluid method is used to model the splitting process of gas bubbles passing through artery and arteriole bifurcations. The model reproduces the variety of splitting behaviors observed experimentally, including the bubble reversal phenomenon. Splitting homogeneity and maximum shear stress along the vessel walls is predicted over a variety of physical parameters. Small bubbles, having initial length less than twice the vessel diameter, were found unlikely to split in the presence of gravitational asymmetry. Maximum shear stresses were found to decrease exponentially with increasing Reynolds number. Vortex-induced shearing near the bifurcation is identified as a possible mechanism for endothelial cell damage.

Solubilization of flurbiprofen within non-ionic Tween 20 surfactant micelles: a 19F and 1H NMR study.

PubMed

Saveyn, Pieter; Cocquyt, Ellen; Zhu, Wuxin; Sinnaeve, Davy; Haustraete, Katrien; Martins, José C; Van der Meeren, Paul

2009-07-14

The solubilization of the poorly water soluble anti-inflammatory drug flurbiprofen in non-ionic Tween 20 surfactant micellar solutions was studied by both (19)F and (1)H NMR spectroscopy in an acidic environment. These non-destructive techniques allowed us to investigate the effect of temperature cycling in situ. Using (19)F NMR, an increased solubilisation capacity was observed as the temperature increased. This effect became more pronounced above the cloud point, which was reduced by more than 30 degrees C in the presence of an excess of flurbiprofen. Upon clouding, peak splitting was observed in the (19)F spectrum, which indicates that two pools of solubilised flurbiprofen exist that are in slow exchange on the NMR frequency timescale. The clouding and solubilization processes were found to be reversible, albeit with slow kinetics. Based on chemical shift differences of both Tween 20 and flurbiprofen, as well as NOESY experiments, the flurbiprofen was found to be accumulated within the palisade layer of the Tween 20 micelles.

Population Genomic Analysis Reveals a Rich Speciation and Demographic History of Orang-utans (Pongo pygmaeus and Pongo abelii)

PubMed Central

Ma, Xin; Kelley, Joanna L.; Eilertson, Kirsten; Musharoff, Shaila; Degenhardt, Jeremiah D.; Martins, André L.; Vinar, Tomas; Kosiol, Carolin; Siepel, Adam; Gutenkunst, Ryan N.; Bustamante, Carlos D.

2013-01-01

To gain insights into evolutionary forces that have shaped the history of Bornean and Sumatran populations of orang-utans, we compare patterns of variation across more than 11 million single nucleotide polymorphisms found by previous mitochondrial and autosomal genome sequencing of 10 wild-caught orang-utans. Our analysis of the mitochondrial data yields a far more ancient split time between the two populations (∼3.4 million years ago) than estimates based on autosomal data (0.4 million years ago), suggesting a complex speciation process with moderate levels of primarily male migration. We find that the distribution of selection coefficients consistent with the observed frequency spectrum of autosomal non-synonymous polymorphisms in orang-utans is similar to the distribution in humans. Our analysis indicates that 35% of genes have evolved under detectable negative selection. Overall, our findings suggest that purifying natural selection, genetic drift, and a complex demographic history are the dominant drivers of genome evolution for the two orang-utan populations. PMID:24194868

Population genomic analysis reveals a rich speciation and demographic history of orang-utans (Pongo pygmaeus and Pongo abelii).

PubMed

Ma, Xin; Kelley, Joanna L; Eilertson, Kirsten; Musharoff, Shaila; Degenhardt, Jeremiah D; Martins, André L; Vinar, Tomas; Kosiol, Carolin; Siepel, Adam; Gutenkunst, Ryan N; Bustamante, Carlos D

2013-01-01

To gain insights into evolutionary forces that have shaped the history of Bornean and Sumatran populations of orang-utans, we compare patterns of variation across more than 11 million single nucleotide polymorphisms found by previous mitochondrial and autosomal genome sequencing of 10 wild-caught orang-utans. Our analysis of the mitochondrial data yields a far more ancient split time between the two populations (~3.4 million years ago) than estimates based on autosomal data (0.4 million years ago), suggesting a complex speciation process with moderate levels of primarily male migration. We find that the distribution of selection coefficients consistent with the observed frequency spectrum of autosomal non-synonymous polymorphisms in orang-utans is similar to the distribution in humans. Our analysis indicates that 35% of genes have evolved under detectable negative selection. Overall, our findings suggest that purifying natural selection, genetic drift, and a complex demographic history are the dominant drivers of genome evolution for the two orang-utan populations.

Measurement and Mitigation of the Ionosphere in L-Band Interferometric SAR Data

NASA Technical Reports Server (NTRS)

Rosen, Paul A.; Hensley, Scott; Chen, Curtis

2010-01-01

Satellite-based repeat-pass Interferometric Synthetic Aperture Radar (InSAR) provides a synoptic high spatial resolution perspective of Earth's changing surface, permitting one to view large areas quickly and efficiently. By measuring relative phase change from one observation to the next on a pixel-by-pixel basis, maps of deformation and change can be derived. Variability of the atmosphere and the ionosphere leads to phase/time delays that are present in the data that can mask many of the subtle deformation signatures of interest, so methods for mitigation of these effects are important. Many of these effects have been observed in existing ALOS PALSAR data, and studies are underway to characterize and mitigate the ionosphere using these data. Since the ionosphere is a dispersive medium, it is possible in principle distinguish the ionospheric signatures from the non-dispersive effects of deformation and the atmosphere. In this paper, we describe a method for mapping the ionosphere in InSAR data based on a multi-frequency split-spectrum processing technique.

Local environment of iron in garden soil Vs Plants

NASA Astrophysics Data System (ADS)

Dehipawala, Sunil; Dong, Chaojung; Smith, Stephen; Schneider, Patricia; Gafney, Harry

2015-03-01

Iron is an essential nutrient not only for humans, but also for all types of plants. Plants use iron for chlorophyll formation, RNA metabolism, and transpiration process regulation. Iron is one of the most abundant metals in the soil and occurs in a wide range of chemical forms. The correlation between the iron species presents in soil and in Petroselinum crispum (parsley) plants were investigated using the room temperature Mossbauer spectroscopy. Mossbauer spectrum of garden soil consists of two doublets. Based on the established isomer shift and quadrupole splitting values of iron, these doublets can be identified as due to octahedrally coordinated Fe3+ and tetrahedrally coordinated Fe2+. Most of the iron present in the parsley has the form Fe3+ or electron density at the site of the iron nucleus similar to that of Fe3+. These findings will help establish soil conditions necessary to increase Fe2+ intake by plants similar to the form of iron present in most supplements. Sunil Dehipawala acknowledges financial support provided by PSC-CUNY.

Plasmon resonance and perfect light absorption in subwavelength trench arrays etched in gallium-doped zinc oxide film

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

Hendrickson, Joshua R., E-mail: joshua.hendrickson.4@us.af.mil; Leedy, Kevin; Cleary, Justin W.

Near-perfect light absorption in subwavelength trench arrays etched in highly conductive gallium-doped zinc oxide films was experimentally observed in the mid infrared regime. At wavelengths corresponding to the resonant excitation of surface plasmons, up to 99% of impinging light is efficiently trapped and absorbed in the periodic trenches. Scattering cross sectional calculations reveal that each individual trench acts like a vertical split ring resonator with a broad plasmon resonance spectrum. The coupling of these individual plasmon resonators in the grating structure leads to enhanced photon absorption and significant resonant spectral linewidth narrowing. Ellipsometry measurements taken before and after device fabricationmore » result in different permittivity values for the doped zinc oxide material, indicating that localized annealing occurred during the plasma etching process due to surface heating. Simulations, which incorporate a 50 nm annealed region at the zinc oxide surface, are in a good agreement with the experimental results.« less

Anomalous torsional tripling in the ν9 and ν10 CH3-deformation modes of ethane 12CH313CH3

NASA Astrophysics Data System (ADS)

Lattanzi, F.; di Lauro, C.

2017-12-01

We have investigated the anomalous torsional behavior in the coupled ν9 and ν10 vibrational fundamentals of 12CH313CH3, both states exhibiting a splitting into three components, instead of two, only in those rotational levels which are very close to resonance. We conclude that the intrinsic additional splitting, which occurs in the E-torsional components, for these two vibrational states is too small to be detected in the high resolution infrared spectrum, but it is substantively enhanced by their coupling. It is shown that this effect requires the simultaneous action of torsion independent operators, such as Fermi-type and z-Coriolis, not allowed in the more symmetric isotopologue 12CH312CH3, and torsion dependent operators, such as torsional-Coriolis, connecting the two vibrational states. Our conclusions lead to a simple model for the coupling of ν9 and ν10, with effective Fermi-type matrix elements W for the A-torsional components, and W ± w for the two pairs of E-torsional components. This causes the additional splitting in the E-pairs. This model is consistent with the mechanism causing the Coriolis-dependent decrease of the A-E torsional splitting in degenerate vibrational states. Exploratory calculations were performed making use of results from a normal mode analysis, showing that the effects predictable by the proposed model are of the correct order of magnitude compared to the observed features, with coupling parameter values reasonably consistent with those determined by the least squares fit of the observed transition wavenumbers.

Interplay of oxygen-evolution kinetics and photovoltaic power curves on the construction of artificial leaves

PubMed Central

Surendranath, Yogesh; Bediako, D. Kwabena; Nocera, Daniel G.

2012-01-01

An artificial leaf can perform direct solar-to-fuels conversion. The construction of an efficient artificial leaf or other photovoltaic (PV)-photoelectrochemical device requires that the power curve of the PV material and load curve of water splitting, composed of the catalyst Tafel behavior and cell resistances, be well-matched near the thermodynamic potential for water splitting. For such a condition, we show here that the current density-voltage characteristic of the catalyst is a key determinant of the solar-to-fuels efficiency (SFE). Oxidic Co and Ni borate (Co-Bi and Ni-Bi) thin films electrodeposited from solution yield oxygen-evolving catalysts with Tafel slopes of 52 mV/decade and 30 mV/decade, respectively. The consequence of the disparate Tafel behavior on the SFE is modeled using the idealized behavior of a triple-junction Si PV cell. For PV cells exhibiting similar solar power-conversion efficiencies, those displaying low open circuit voltages are better matched to catalysts with low Tafel slopes and high exchange current densities. In contrast, PV cells possessing high open circuit voltages are largely insensitive to the catalyst’s current density-voltage characteristics but sacrifice overall SFE because of less efficient utilization of the solar spectrum. The analysis presented herein highlights the importance of matching the electrochemical load of water-splitting to the onset of maximum current of the PV component, drawing a clear link between the kinetic profile of the water-splitting catalyst and the SFE efficiency of devices such as the artificial leaf. PMID:22689962

Strategies to achieve high-solids enzymatic hydrolysis of dilute-acid pretreated corn stover.

PubMed

Geng, Wenhui; Jin, Yongcan; Jameel, Hasan; Park, Sunkyu

2015-01-01

Three strategies were presented to achieve high solids loading while maximizing carbohydrate conversion, which are fed-batch, splitting/thickening, and clarifier processes. Enzymatic hydrolysis was performed at water insoluble solids (WIS) of 15% using washed dilute-acid pretreated corn stover. The carbohydrate concentration increased from 31.8 to 99.3g/L when the insoluble solids content increased from 5% to 15% WIS, while the final carbohydrate conversion was decreased from 78.4% to 73.2%. For the fed-batch process, a carbohydrate conversion efficiency of 76.8% was achieved when solid was split into 60:20:20 ratio, with all enzymes added first. For the splitting/thickening process, a carbohydrate conversion of 76.5% was realized when the filtrate was recycled to simulate a steady-state process. Lastly, the clarifier process was evaluated and the highest carbohydrate conversion of 81.4% was achieved. All of these results suggests the possibility of enzymatic hydrolysis at high solids to make the overall conversion cost-competitive. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of selected volatile organic compounds in split and nonsplit swiss cheese samples using selected-ion flow tube mass spectrometry (SIFT-MS).

PubMed

Castada, Hardy Z; Wick, Cheryl; Taylor, Kaitlyn; Harper, W James

2014-04-01

Splits/cracks are recurring product defects that negatively affect the Swiss cheese industry. Investigations to understand the biophysicochemical aspects of these defects, and thus determine preventive measures against their occurrence, are underway. In this study, selected-ion, flow tube mass spectrometry was employed to determine the volatile organic compound (VOC) profiles present in the headspace of split compared with nonsplit cheeses. Two sampling methodologies were employed: split compared with nonsplit cheese vat pair blocks; and comparison of blind, eye, and split segments within cheese blocks. The variability in VOC profiles was examined to evaluate the potential biochemical pathway chemistry differences within and between cheese samples. VOC profile inhomogeneity was most evident in cheeses between factories. Evaluation of biochemical pathways leading to the formation of key VOCs differentiating the split from the blind and eye segments within factories indicated release of additional carbon dioxide by-product. These results suggest a factory-dependent cause of split formation that could develop from varied fermentation pathways in the blind, eye, and split areas within a cheese block. The variability of VOC profiles within and between factories exhibit varied biochemical fermentation pathways that could conceivably be traced back in the making process to identify parameters responsible for split defect. © 2014 Institute of Food Technologists®

Zinc oxide nanostructures and its nano-compounds for efficient visible light photo-catalytic processes

NASA Astrophysics Data System (ADS)

Adam, Rania E.; Alnoor, Hatim; Elhag, Sami; Nur, Omer; Willander, Magnus

2017-02-01

Zinc oxide (ZnO) in its nanostructure form is a promising material for visible light emission/absorption and utilization in different energy efficient photocatalytic processes. We will first present our recent results on the effect of varying the molar ratio of the synthesis nutrients on visible light emission. Further we will use the optimized conditions from the molar ration experiments to vary the synthesis processing parameters like stirring time etc. and the effect of all these parameters in order to optimize the efficiency and control the emission spectrum are investigated using different complementary techniques. Cathodoluminescence (CL) is combined with photoluminescence (PL) and electroluminescence (EL) as the techniques to investigate and optimizes visible light emission from ZnO/GaN light emitting diodes. We will then show and discuss our recent finding of the use of high quality ZnO nanoparticles (NPs) for efficient photo-degradation of toxic dyes using the visible spectra, namely with a wavelength up to 800 nm. In the end, we show how ZnO nanorods (NRs) are used as the first template to be transferred to bismuth zinc vanadate (BiZn2VO6). The BiZn2VO6 is then used to demonstrate efficient and cost effective hydrogen production through photoelectrochemical water splitting using solar radiation.

TH-CD-202-04: Evaluation of Virtual Non-Contrast Images From a Novel Split-Filter Dual-Energy CT Technique

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

Huang, J; Szczykutowicz, T; Bayouth, J

Purpose: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. Methods: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7–20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between themore » acquisition of low- and high-energy data. Additionally, VNC images were generated with the sequential-scan technique (80 and 140kVp) for comparison. CT number accuracy was evaluated for all materials at 15, 25, and 35mGy CTDIvol. Results: The spectral separation was greater for the sequential-scan technique than the split-filter technique with dual-energy ratios of 2.18 and 1.26, respectively. Both techniques successfully removed iodine contrast, resulting in mean CT numbers within 60HU of 0HU (split-filter) and 40HU of 0HU (sequential-scan) for all iodine concentrations. Additionally, for iodine vials of varying diameter (2–20 mm) with the same concentration (9.9 mg I /mL), the system accurately detected iodine for all sizes investigated. Both dual-energy techniques resulted in reduced CT numbers for bone materials (by >400HU for the densest bone). Increasing the imaging dose did not improve the CT number accuracy for bone in VNC images. Conclusion: VNC images from the split-filter technique successfully removed iodine contrast. These results demonstrate a potential for improving dose calculation accuracy and reducing patient imaging dose, while achieving superior temporal resolution in comparison sequential scans. For both techniques, inaccuracies in CT numbers for bone materials necessitate consideration for radiation therapy treatment planning.« less

The microwave spectrum of a triplet carbene: HCCN in the X 3Sigma - state

NASA Astrophysics Data System (ADS)

Saito, Shuji; Endo, Yasuki; Hirota, Eizi

1984-02-01

A simple carbene, the HCCN radical, has been identified in the gas phase using a microwave spectroscopic method. The HCCN molecule was generated in a free space absorption cell by the reaction of CH3CN with the microwave discharge products of CF4. Five rotational transitions, each split into three fine structure components, were observed in the region of 110 to 198 GHz. No hyperfine structure was resolved, although some of the observed lines showed broadening. The rotational constant, the centrifugal distortion constant, the spin-spin coupling constant, and the spin-rotation coupling constant were determined with good precision. The observed spectrum is completely consistent with that expected for a linear molecule in a 3Σ state, in agreement with an earlier matrix EPR study of Bernheim et al. [J. Chem. Phys. 43, 196 (1965)].

THE HYPERFINE STRUCTURE OF THE ROTATIONAL SPECTRUM OF HDO AND ITS EXTENSION TO THE THz REGION: ACCURATE REST FREQUENCIES AND SPECTROSCOPIC PARAMETERS FOR ASTROPHYSICAL OBSERVATIONS

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

Cazzoli, Gabriele; Lattanzi, Valerio; Puzzarini, Cristina

2015-06-10

The rotational spectrum of the mono-deuterated isotopologue of water, HD{sup 16}O, has been investigated in the millimeter- and submillimeter-wave frequency regions, up to 1.6 THz. The Lamb-dip technique has been exploited to obtain sub-Doppler resolution and to resolve the hyperfine (hf) structure due to the deuterium and hydrogen nuclei, thus enabling the accurate determination of the corresponding hf parameters. Their experimental determination has been supported by high-level quantum-chemical calculations. The Lamb-dip measurements have been supplemented by Doppler-limited measurements (weak high-J and high-frequency transitions) in order to extend the predictive capability of the available spectroscopic constants. The possibility of resolving hfmore » splittings in astronomical spectra has been discussed.« less

The torsional barriers of two equivalent methyl internal rotations in 2,5-dimethylfuran investigated by microwave spectroscopy

NASA Astrophysics Data System (ADS)

Van, Vinh; Bruckhuisen, Jonas; Stahl, Wolfgang; Ilyushin, Vadim; Nguyen, Ha Vinh Lam

2018-01-01

The microwave spectrum of 2,5-dimethylfuran was recorded using two pulsed molecular jet Fourier transform microwave spectrometers which cover the frequency range from 2 to 40 GHz. The internal rotations of two equivalent methyl tops with a barrier height of approximately 439.15 cm-1 introduce torsional splittings of all rotational transitions in the spectrum. For the spectral analysis, two different computer programs were applied and compared, the PAM-C2v-2tops code based on the principal axis method which treats several torsional states simultaneously, and the XIAM code based on the combined axis method, yielding accurate molecular parameters. The experimental work was supplemented by quantum chemical calculations. Two-dimensional potential energy surfaces depending on the torsional angles of both methyl groups were calculated and parametrized.

The Movement of Conflict in Organizations: The Joint Dynamics of Splitting and Triangulation.

ERIC Educational Resources Information Center

Smith, Kenwyn K.

1989-01-01

Based on a long-term public school system study, the paper examines the sociopsychological process through which conflicts move around in organizations and are transported from one place to another. The conceptualization draws on "triangulation" from social psychology and family therapy and "splitting," developed in…

Split-remerge method for eliminating processing window artifacts in recursive hierarchical segmentation

NASA Technical Reports Server (NTRS)

Tilton, James C. (Inventor)

2010-01-01

A method, computer readable storage, and apparatus for implementing recursive segmentation of data with spatial characteristics into regions including splitting-remerging of pixels with contagious region designations and a user controlled parameter for providing a preference for merging adjacent regions to eliminate window artifacts.

Structural, (197)Au Mössbauer and solid state (31)P CP/MAS NMR studies on bis (cis-bis(diphenylphosphino)ethylene) gold(I) complexes [Au(dppey)(2)]X for X = PF(6), I.

PubMed

Healy, Peter C; Loughrey, Bradley T; Bowmaker, Graham A; Hanna, John V

2008-07-28

(197)Au Mössbauer spectra for the d(10) gold(i) phosphine complexes, [Au(dppey)(2)]X (X = PF(6), I; dppey = (cis-bis(diphenylphosphino)ethylene), and the single crystal X-ray structure and solid state (31)P CPMAS NMR spectrum of [Au(dppey)(2)]I are reported here. In [Au(dppey)(2)]I the AuP(4) coordination geometry is distorted from the approximately D(2) symmetry observed for the PF(6)(-) complex with Au-P bond lengths 2.380(2)-2.426(2) A and inter-ligand P-Au-P angles 110.63(5)-137.71(8) degrees . Quadrupole splitting parameters derived from the Mössbauer spectra are consistent with the increased distortion of the AuP(4) coordination sphere with values of 1.22 and 1.46 mm s(-1) for the PF(6)(-) and I(-) complexes respectively. In the solid state (31)P CP MAS NMR spectrum of [Au(dppey)(2)]I, signals for each of the four crystallographically independent phosphorus nuclei are observed, with the magnitude of the (197)Au quadrupole coupling being sufficiently large to produce a collapse of (1)J(Au-P) splitting from quartets to doublets. The results highlight the important role played by the counter anion in the determination of the structural and spectroscopic properties of these sterically crowded d(10) complexes.

Structure, internal mobility, and spectrum of the ammonia dimer: Calculation of the vibration-rotation-tunneling states

NASA Astrophysics Data System (ADS)

Olthof, E. H. T.; van der Avoird, A.; Wormer, P. E. S.

1994-11-01

We have obtained a potential for (NH3)2 by calculating the six-dimensional vibra- tion-rotation-tunneling (VRT) states from a model potential with some variable parameters, and adjusting some calculated transition frequencies to the observed far-infrared spectrum. The equilibrium geometry is strongly bent away from a linear hydrogen bonded structure. Equivalent minima with the proton donor and acceptor interchanged are separated by a barrier of only 7 cm-1. The barriers to rotation of the monomers about their C3 axes are much higher. The VRT levels from this potential agree to about 0.25 cm-1 with all far-infrared frequencies of (NH3)2 observed for K=0, ‖K‖=1, and ‖K‖=2 and for all the symmetry species: Ai=ortho-ortho, Ei=para-para, and G=ortho-para. Moreover, the dipole moments and the nuclear quadrupole splittings agree well with the values that are observed for the G states. The potential has been explicitly transformed to the center-of-mass coordinates of (ND3)2 and used to study the effects of the deuteration on the VRT states. The observed decrease of the dipole moment and the (small) changes in the nuclear quadrupole splittings are well reproduced. It follows from our calculations that the ammonia dimer is highly nonrigid and that vibrational averaging effects are essential. Seemingly contradictory effects of this averaging on its properties are the consequence of the different hindered rotor behavior of ortho and para monomers.

[Glossary of terms used by radiologists in image processing].

PubMed

Rolland, Y; Collorec, R; Bruno, A; Ramée, A; Morcet, N; Haigron, P

1995-01-01

We give the definition of 166 words used in image processing. Adaptivity, aliazing, analog-digital converter, analysis, approximation, arc, artifact, artificial intelligence, attribute, autocorrelation, bandwidth, boundary, brightness, calibration, class, classification, classify, centre, cluster, coding, color, compression, contrast, connectivity, convolution, correlation, data base, decision, decomposition, deconvolution, deduction, descriptor, detection, digitization, dilation, discontinuity, discretization, discrimination, disparity, display, distance, distorsion, distribution dynamic, edge, energy, enhancement, entropy, erosion, estimation, event, extrapolation, feature, file, filter, filter floaters, fitting, Fourier transform, frequency, fusion, fuzzy, Gaussian, gradient, graph, gray level, group, growing, histogram, Hough transform, Houndsfield, image, impulse response, inertia, intensity, interpolation, interpretation, invariance, isotropy, iterative, JPEG, knowledge base, label, laplacian, learning, least squares, likelihood, matching, Markov field, mask, matching, mathematical morphology, merge (to), MIP, median, minimization, model, moiré, moment, MPEG, neural network, neuron, node, noise, norm, normal, operator, optical system, optimization, orthogonal, parametric, pattern recognition, periodicity, photometry, pixel, polygon, polynomial, prediction, pulsation, pyramidal, quantization, raster, reconstruction, recursive, region, rendering, representation space, resolution, restoration, robustness, ROC, thinning, transform, sampling, saturation, scene analysis, segmentation, separable function, sequential, smoothing, spline, split (to), shape, threshold, tree, signal, speckle, spectrum, spline, stationarity, statistical, stochastic, structuring element, support, syntaxic, synthesis, texture, truncation, variance, vision, voxel, windowing.

Non-destructive splitter of twisted light based on modes splitting in a ring cavity.

PubMed

Li, Yan; Zhou, Zhi-Yuan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

2016-02-08

Efficiently discriminating beams carrying different orbital angular momentum (OAM) is of fundamental importance for various applications including high capacity optical communication and quantum information processing. We design and experimentally verify a distinguished method for effectively splitting different OAM-carried beams by introducing Dove prisms in a ring cavity. Because of rotational symmetry broken of two OAM-carried beams with opposite topological charges, their transmission spectra will split. When mode and impedance matches between the cavity and one OAM-carried beam are achieved, this beam will transmit through the cavity and other beam will be reflected, both beams keep their spatial shapes. In this case, the cavity acts like a polarized beam splitter. Besides, the transmitting beam can be selected at your will, the splitting efficiency can reach unity if the cavity is lossless and it completely matches the beam. Furthermore, beams carry multi-OAMs can also be split by cascading ring cavities.

Obsessive-compulsive disorder spectrum as a scientific "metaphor".

PubMed

Pallanti, Stefano; Hollander, Eric

2008-09-01

As a result of clinical, epidemiological, neuroimaging, and therapy studies that took place in the late 1980s, obsessive-compulsive disorder (OCD) has been well-characterized in the field of anxiety disorders. Other disorders attracted attention for their similarities to OCD, and were located in the orbit of the disorder. OCD has become known as the "primary domain" of a scientific "metaphor" comprising the putative cluster of OCD-related disorders (OCRDs). It is a "paradigm" with which to explore basal ganglia dysfunction. The OCRDs share common phenomenology, comorbidities, lifetime course, demographics, possible genetics, and frontostriatal dysfunction (particularly caudate hyperactivity.) The adoption of this metaphor analogy has proven useful. However, 15 years since its emergence, the spectrum of obsessive-compulsive disorders remains controversial. Questions under debate include whether OCD is a unitary or split condition, whether it is an anxiety disorder, and whether there exists only one spectrum or several possible spectrums. Further work is needed to clarify obsessive-compulsive symptoms, subtypes, and endophenotypes. There is need to integrate existing databases, better define associated symptom domains, and create a more comprehensive endophenotyping protocol for OCRDs. There is also a need to integrate biological and psychological perspectives, concepts, and data to drive this evolution. By increasing research in this field, the OCD spectrum may evolve from a fragmented level of conceptualization as a "metaphor" to one that is more comprehensive and structured.

Introducing inducible fluorescent split cholesterol oxidase to mammalian cells.

PubMed

Chernov, Konstantin G; Neuvonen, Maarit; Brock, Ivonne; Ikonen, Elina; Verkhusha, Vladislav V

2017-05-26

Cholesterol oxidase (COase) is a bacterial enzyme catalyzing the first step in the biodegradation of cholesterol. COase is an important biotechnological tool for clinical diagnostics and production of steroid drugs and insecticides. It is also used for tracking intracellular cholesterol; however, its utility is limited by the lack of an efficient temporal control of its activity. To overcome this we have developed a regulatable fragment complementation system for COase cloned from Chromobacterium sp. The enzyme was split into two moieties that were fused to FKBP (FK506-binding protein) and FRB (rapamycin-binding domain) pair and split GFP fragments. The addition of rapamycin reconstituted a fluorescent enzyme, termed split GFP-COase, the fluorescence level of which correlated with its oxidation activity. A rapid decrease of cellular cholesterol induced by intracellular expression of the split GFP-COase promoted the dissociation of a cholesterol biosensor D4H from the plasma membrane. The process was reversible as upon rapamycin removal, the split GFP-COase fluorescence was lost, and cellular cholesterol levels returned to normal. These data demonstrate that the split GFP-COase provides a novel tool to manipulate cholesterol in mammalian cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Direct variational data assimilation algorithm for atmospheric chemistry data with transport and transformation model

NASA Astrophysics Data System (ADS)

Penenko, Alexey; Penenko, Vladimir; Nuterman, Roman; Baklanov, Alexander; Mahura, Alexander

2015-11-01

Atmospheric chemistry dynamics is studied with convection-diffusion-reaction model. The numerical Data Assimilation algorithm presented is based on the additive-averaged splitting schemes. It carries out ''fine-grained'' variational data assimilation on the separate splitting stages with respect to spatial dimensions and processes i.e. the same measurement data is assimilated to different parts of the split model. This design has efficient implementation due to the direct data assimilation algorithms of the transport process along coordinate lines. Results of numerical experiments with chemical data assimilation algorithm of in situ concentration measurements on real data scenario have been presented. In order to construct the scenario, meteorological data has been taken from EnviroHIRLAM model output, initial conditions from MOZART model output and measurements from Airbase database.

Coherent and dynamic beam splitting based on light storage in cold atoms

PubMed Central

Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho

2016-01-01

We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing. PMID:27677457

Interim results of quality-control sampling of surface water for the Upper Colorado River National Water-Quality Assessment Study Unit, water years 1995-96

USGS Publications Warehouse

Spahr, N.E.; Boulger, R.W.

1997-01-01

Quality-control samples provide part of the information needed to estimate the bias and variability that result from sample collection, processing, and analysis. Quality-control samples of surface water collected for the Upper Colorado River National Water-Quality Assessment study unit for water years 1995?96 are presented and analyzed in this report. The types of quality-control samples collected include pre-processing split replicates, concurrent replicates, sequential replicates, post-processing split replicates, and field blanks. Analysis of the pre-processing split replicates, concurrent replicates, sequential replicates, and post-processing split replicates is based on differences between analytical results of the environmental samples and analytical results of the quality-control samples. Results of these comparisons indicate that variability introduced by sample collection, processing, and handling is low and will not affect interpretation of the environmental data. The differences for most water-quality constituents is on the order of plus or minus 1 or 2 lowest rounding units. A lowest rounding unit is equivalent to the magnitude of the least significant figure reported for analytical results. The use of lowest rounding units avoids some of the difficulty in comparing differences between pairs of samples when concentrations span orders of magnitude and provides a measure of the practical significance of the effect of variability. Analysis of field-blank quality-control samples indicates that with the exception of chloride and silica, no systematic contamination of samples is apparent. Chloride contamination probably was the result of incomplete rinsing of the dilute cleaning solution from the outlet ports of the decaport sample splitter. Silica contamination seems to have been introduced by the blank water. Sampling and processing procedures for water year 1997 have been modified as a result of these analyses.

Development of the tongue coating analyzer based on concave grating monochrometer and virtual instrument

NASA Astrophysics Data System (ADS)

Ren, Zhong; Liu, Guodong; Zeng, Lvming; Huang, Zhen; Zeng, Wenping

2010-10-01

The tongue coating diagnosis is an important part in tongue diagnosis of traditional Chinese medicine (TCM).The change of the thickness and color of the tongue coating can reflect the pathological state for the patient. By observing the tongue coating, a Chinese doctor can determine the nature or severity of disease. Because some limitations existed in the tongue diagnosis method of TCM and the method based on the digital image processing, a novel tongue coating analyzer(TCA) based on the concave grating monochrometer and virtual instrument is developed in this paper. This analyzer consists of the light source system, check cavity, optical fiber probe, concave grating monochrometer, spectrum detector system based on CCD and data acquisition (DAQ) card, signal processing circuit system, computer and data analysis software based on LabVIEW, etc. Experimental results show that the novel TCA's spectral range can reach 300-1000 nm, its wavelength resolution can reach 1nm, and this TCA uses the back-split-light technology and multi-channel parallel analysis. Compared with the TCA based on the image processing technology, this TCA has many advantages, such as, compact volume, simpler algorithm, faster processing speed, higher accuracy, cheaper cost and real-time handle data and display the result, etc. Therefore, it has the greatly potential values in the fields of the tongue coating diagnosis for TCM.

Understanding charge transfer dynamics in QDs-TiO2 nanorod array photoanodes for solar fuel generation

NASA Astrophysics Data System (ADS)

Li, Jiangtian; McClure, Joshua P.; Fu, Richard; Jiang, Rongzhong; Chu, Deryn

2018-01-01

Harvesting light to drive water splitting for hydrogen generation is an attractive approach to satisfy the urgent energy demands. The design and fabrication of photoelectrode materials that are able to harvest sunlight is an important scientific undertaking. In this study, a two-quantum-dot (QD) layer is developed to decorate one-dimensional TiO2 nanorod arrays, which are subsequently utilized as photoanodes to harvest the wide-spectrum sunlight for water splitting. The QD-coated TiO2 nanorod arrays extend the light absorption range from the UV into the visible region yielding increased solar-to-hydrogen efficiencies. Transient photocurrent decay measurements demonstrate that the multi-layer CdSe-CdS QDs deposited onto the TiO2 nanorod arrays result in a stepwise band alignment that not only improves the hole extraction but also facilitates electron injection from the QDs to TiO2 rods. Moreover, the multi-heterojunction photoanode introduces interfacial states that act as recombination centers to trap the photogenerated electrons.

ScanIndel: a hybrid framework for indel detection via gapped alignment, split reads and de novo assembly.

PubMed

Yang, Rendong; Nelson, Andrew C; Henzler, Christine; Thyagarajan, Bharat; Silverstein, Kevin A T

2015-12-07

Comprehensive identification of insertions/deletions (indels) across the full size spectrum from second generation sequencing is challenging due to the relatively short read length inherent in the technology. Different indel calling methods exist but are limited in detection to specific sizes with varying accuracy and resolution. We present ScanIndel, an integrated framework for detecting indels with multiple heuristics including gapped alignment, split reads and de novo assembly. Using simulation data, we demonstrate ScanIndel's superior sensitivity and specificity relative to several state-of-the-art indel callers across various coverage levels and indel sizes. ScanIndel yields higher predictive accuracy with lower computational cost compared with existing tools for both targeted resequencing data from tumor specimens and high coverage whole-genome sequencing data from the human NIST standard NA12878. Thus, we anticipate ScanIndel will improve indel analysis in both clinical and research settings. ScanIndel is implemented in Python, and is freely available for academic use at https://github.com/cauyrd/ScanIndel.

Precision measurement of the local bias of dark matter halos

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

Lazeyras, Titouan; Wagner, Christian; Schmidt, Fabian

2016-02-01

We present accurate measurements of the linear, quadratic, and cubic local bias of dark matter halos, using curved 'separate universe' N-body simulations which effectively incorporate an infinite-wavelength overdensity. This can be seen as an exact implementation of the peak-background split argument. We compare the results with the linear and quadratic bias measured from the halo-matter power spectrum and bispectrum, and find good agreement. On the other hand, the standard peak-background split applied to the Sheth and Tormen (1999) and Tinker et al. (2008) halo mass functions matches the measured linear bias parameter only at the level of 10%. The predictionmore » from the excursion set-peaks approach performs much better, which can be attributed to the stochastic moving barrier employed in the excursion set-peaks prediction. We also provide convenient fitting formulas for the nonlinear bias parameters b{sub 2}(b{sub 1}) and b{sub 3}(b{sub 1}), which work well over a range of redshifts.« less

Nematicity and magnetism in LaFeAsO single crystals probed by 75As nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Ok, J. M.; Baek, S.-H.; Efremov, D. V.; Kappenberger, R.; Aswartham, S.; Kim, J. S.; van den Brink, Jeroen; Büchner, B.

2018-05-01

We report a 75As nuclear magnetic resonance study in LaFeAsO single crystals, which undergoes nematic and antiferromagnetic transitions at Tnem˜156 K and TN˜138 K, respectively. Below Tnem, the 75As spectrum splits sharply into two for an external magnetic field parallel to the orthorhombic a or b axis in the FeAs planes. Our analysis of the data demonstrates that the NMR line splitting arises from an electronically driven rotational symmetry breaking. The 75As spin-lattice relaxation rate as a function of temperature shows that spin fluctuations are strongly enhanced just below Tnem. These NMR findings indicate that nematic order promotes spin fluctuations in magnetically ordered LaFeAsO, as observed in nonmagnetic and superconducting FeSe. We conclude that the origin of nematicity is identical in both FeSe and LaFeAsO regardless of whether or not a long-range magnetic order develops in the nematic state.

Tandem luminescent solar concentrators based on engineered quantum dots

NASA Astrophysics Data System (ADS)

Wu, Kaifeng; Li, Hongbo; Klimov, Victor I.

2018-02-01

Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors for terrestrial and space-based photovoltaics. Due to their high emission efficiencies and readily tunable emission and absorption spectra, colloidal quantum dots have emerged as a new and promising type of LSC fluorophore. Spectral tunability of the quantum dots also facilitates the realization of stacked multilayered LSCs, where enhanced performance is obtained through spectral splitting of incident sunlight, as in multijunction photovoltaics. Here, we demonstrate a large-area (>230 cm2) tandem LSC based on two types of nearly reabsorption-free quantum dots spectrally tuned for optimal solar-spectrum splitting. This prototype device exhibits a high optical quantum efficiency of 6.4% for sunlight illumination and solar-to-electrical power conversion efficiency of 3.1%. The efficiency gains due to the tandem architecture over single-layer devices quickly increase with increasing LSC size and can reach more than 100% in structures with window sizes of more than 2,500 cm2.

A mechanism for plasma waves at the harmonics of the plasma frequency foreshock boundary

NASA Technical Reports Server (NTRS)

Klimas, A. J.

1982-01-01

A bump-on-tail unstable reduced velocity distribution, constructed from data obtained at the upstream boundary of the electron foreshock by the GSFC electron spectrometer experiment on the ISEE-1 satellite, is used as the initial plasma state for a numerical integration of the 1D-Vlasov-Maxwell system of equations. The integration is carried through the growth of the instability, beyond its saturation, and well into the stabilized plasma regime. A power spectrum computed for the electric field of the stabilized plasma is dominated by a narrow peak at the Bohm-Gross frequency of the unstable field mode but also contains significant power at the harmonics of the Bohm-Gross frequency. The harmonic power is in sharp peaks which are split into closely spaced doublets. The fundamental peak at the Bohm-Gross frequency is split into a closely spaced triplet. The mechanism for excitation of the second harmonic is shown to be second order wave-wave coupling.

Wave-packet formation at the zero-dispersion point in the Gardner-Ostrovsky equation.

PubMed

Whitfield, A J; Johnson, E R

2015-05-01

The long-time effect of weak rotation on an internal solitary wave is the decay into inertia-gravity waves and the eventual emergence of a coherent, steadily propagating, nonlinear wave packet. There is currently no entirely satisfactory explanation as to why these wave packets form. Here the initial value problem is considered within the context of the Gardner-Ostrovsky, or rotation-modified extended Korteweg-de Vries, equation. The linear Gardner-Ostrovsky equation has maximum group velocity at a critical wave number, often called the zero-dispersion point. It is found here that a nonlinear splitting of the wave-number spectrum at the zero-dispersion point, where energy is shifted into the modulationally unstable regime of the Gardner-Ostrovsky equation, is responsible for the wave-packet formation. Numerical comparisons of the decay of a solitary wave in the Gardner-Ostrovsky equation and a derived nonlinear Schrödinger equation at the zero-dispersion point are used to confirm the spectral splitting.

Characterization of azimuthal and longitudinal modes in rolled-up InGaAs/GaAs microtubes at telecom wavelengths.

PubMed

Zhong, Qiuhang; Tian, Zhaobing; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

2013-08-12

We report on theoretical and experimental investigation of azimuthal and longitudinal modes in rolled-up microtubes at telecom wavelengths. These microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs bilayer. We apply planar waveguide method and a quasi-potential model to analyze the azimuthal and longitudinal modes in the microtubes near 1550 nm. Then we demonstrate these modes in transmission spectrum by evanescent light coupling. The experimental observations agree well with the calculated results. Surface-scattering-induced mode splitting is also observed in both transmission and reflection spectra at ~1600 nm. The mode splitting is in essence the non-degeneracy of clockwise and counter-clockwise whispering-gallery modes of the microtubes. This study is significant for understanding the physics of modes in microtubes and other microcavities with three-dimensional optical confinement, as well as for potential applications such as microtube-based photonic integrated devices and sensing purposes.

Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling

PubMed Central

Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

2016-01-01

Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation. PMID:27324578

Effects of Rashba spin-orbit coupling, Zeeman splitting and gyrotropy in two-dimensional cavity polaritons under the influence of the Landau quantization

NASA Astrophysics Data System (ADS)

Moskalenko, Sveatoslav A.; Podlesny, Igor V.; Dumanov, Evgheni V.; Liberman, Michael A.

2015-09-01

We consider the energy spectrum of the two-dimensional cavity polaritons under the influence of a strong magnetic and electric fields perpendicular to the surface of the GaAs-type quantum wells (QWs) with p-type valence band embedded into the resonators. As the first step in this direction the Landau quantization (LQ) of the electrons and heavy-holes (hh) was investigated taking into account the Rashba spin-orbit coupling (RSOC) with third-order chirality terms for hh and with nonparabolicity terms in their dispersion low including as well the Zeeman splitting (ZS) effects. The nonparabolicity term is proportional to the strength of the electric field and was introduced to avoid the collapse of the semiconductor energy gap under the influence of the third order chirality terms. The exact solutions for the eigenfunctions and eigenenergies were obtained using the Rashba method [E.I. Rashba, Fiz. Tverd. Tela 2, 1224 (1960) [Sov. Phys. Solid State 2, 1109 (1960)

Comprehensive investigation of noble metal nanoparticles shape, size and material on the optical response of optimal plasmonic Y-splitter waveguides

NASA Astrophysics Data System (ADS)

Ahmadivand, Arash; Golmohammadi, Saeed

2014-01-01

With the purpose of guiding and splitting of optical power at C-band spectrum, we studied Y-shape splitters based on various shapes of nanoparticles as a plasmon waveguide. We applied different configurations of Gold (Au) and Silver (Ag) nanoparticles including spheres, rods and rings, to optimize the efficiency and losses of two and four-branch splitters. The best performance in light transportation specifically at telecom wavelength (λ≈1550 nm) is achieved by nanorings, due to an extra degree of freedom in their geometrical components. In addition, comparisons of several values for offset distance (doffset) of examined structures shows that Au nanoring splitters with feasible lower doffset have high quality in guiding and splitting of light through the structure. Finally, we studied four-branch Y-splitters based on Au and Ag nanorings with least possible offset distances to optimize the splitter performance. The power transmission as a key element is calculated for examined structures.

Attosecond transient absorption probing of electronic superpositions of bound states in neon. Detection of quantum beats

DOE PAGES

Beck, Annelise R; Bernhardt, Birgitta; Warrick, Erika R.; ...

2014-11-07

Electronic wavepackets composed of multiple bound excited states of atomic neon lying between 19.6 and 21.5 eV are launched using an isolated attosecond pulse. Individual quantum beats of the wavepacket are detected by perturbing the induced polarization of the medium with a time-delayed few-femtosecond near-infrared (NIR) pulse via coupling the individual states to multiple neighboring levels. All of the initially excited states are monitored simultaneously in the attosecond transient absorption spectrum, revealing Lorentzian to Fano lineshape spectral changes as well as quantum beats. The most prominent beating of the several that were observed was in the spin–orbit split 3d absorptionmore » features, which has a 40 femtosecond period that corresponds to the spin–orbit splitting of 0.1 eV. The few-level models and multilevel calculations confirm that the observed magnitude of oscillation depends strongly on the spectral bandwidth and tuning of the NIR pulse and on the location of possible coupling states.« less

Hyperfine interaction in K 2Ba[Fe(NO 2) 6

NASA Astrophysics Data System (ADS)

Padmakumar, K.; Manoharan, P. T.

2000-04-01

Magnetic hyperfine splitting observed in the low temperature Mössbauer spectrum of potassium barium hexanitro ferrate(II), in the absence of any external field, is attributed to the 5T 2g state of the central metal atom further split into a ground 5E g state and a first excited 5B 2g state under a distorted octahedral symmetry in contrast to the earlier prediction of 1A 1g ground state on the basis of room temperature Mössbauer spectral and other properties. The central iron atom is co-ordianted to six nitrito groups (NO 2-), having an oxidation state of +2. The temperature dependence of Mössbauer spectra is explained on the basis of electronic relaxation among the spin-orbit coupled levels of the 5E g ground state. Various kinds of electronic relaxation mechanisms have been compared to explain the proposed mechanism. The observed temperature dependent spectra with varying internal magnetic field and line width can be explained by simple spin lattice relaxation.

Solving the multiple-set split equality common fixed-point problem of firmly quasi-nonexpansive operators.

PubMed

Zhao, Jing; Zong, Haili

2018-01-01

In this paper, we propose parallel and cyclic iterative algorithms for solving the multiple-set split equality common fixed-point problem of firmly quasi-nonexpansive operators. We also combine the process of cyclic and parallel iterative methods and propose two mixed iterative algorithms. Our several algorithms do not need any prior information about the operator norms. Under mild assumptions, we prove weak convergence of the proposed iterative sequences in Hilbert spaces. As applications, we obtain several iterative algorithms to solve the multiple-set split equality problem.

Materials and systems for unassisted photoelectrochemical solar fuels production (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, Jae Sung

2016-10-01

About 400 semiconductor solids are known to have photocatalytic activity for water splitting. Yet there is no single material that could satisfy all the requirements for desired photocatalysts: i) suitable band gap energy (1.7 eV< Eg < 2.3 eV) for high efficiency, ii) proper band position for reduction and/or oxidation of water, iii) long-term stability in aqueous solutions, iv) low cost, v) high crystallinity, and vi) high conductivity. Hence, in the selection of photocatalytic materials, we better start from intrinsically stable materials made of earth-abundant elements. The band bap energy is also the primary consideration to absorb ample amount of solar energy of wide wavelength spectrum. It sets the limit of theoretically maximum efficiency and it could also be extended by band engineering techniques. Upon selection of the candidate materials, we can also modify the materials for full utilization their potentials. The main path of efficiency loss in PEC water splitting process is recombination of photoelectrons and holes. We discuss the material designs including i) p-n heterojunction photoanodes for effective electron-hole separation, ii) electron highway to facilitate interparticle electron transfer, iii) metal or anion doping to improve conductivity of the semiconductor and to extend the range of light absorption, iv) one-dimensional nanomaterials to secure a short hole diffusion distance and vectoral electron transfer, and v) loading co-catalysts for facile charge separation. High efficiency has been demonstrated for all these examples due to efficient electron-hole separation. Finally, total systems for unassisted solar fuel production are demonstrated.

Energy spectrum and electrical conductivity of graphene with a nitrogen impurity

NASA Astrophysics Data System (ADS)

Repetskii, S. P.; Vyshivanaya, I. G.; Skotnikov, V. A.; Yatsenyuk, A. A.

2015-04-01

The electronic structure of graphene with a nitrogen impurity has been studied based on the model of tight binding using exchange-correlation potentials in the density-functional theory. Wave functions of 2 s and 2 p states of neutral noninteracting carbon atoms have been chosen as the basis. When studying the matrix elements of the Hamiltonian, the first three coordination shells have been taken into account. It has been established that the hybridization of electron-energy bands leads to the splitting of the electron energy spectrum near the Fermi level. Due to the overlap of the energy bands, the arising gap behaves as a quasi-gap, in which the density of the electron levels is much lower than in the rest of the spectrum. It has been established that the conductivity of graphene decreases with increasing nitrogen concentration. Since the increase in the nitrogen concentration leads to an increase in the density of states at the Fermi level, the decrease in the conductivity is due to a sharper decrease in the time of relaxation of the electron sates.

Electron spin resonance spectral analysis of irradiated royal jelly.

PubMed

Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

2014-01-15

The analysis of unpaired electron components in royal jelly was carried out using electron spin resonance (ESR) with the aim to develop a detection method for irradiated royal jelly. The ESR spectrum of royal jelly had natural signals derived from transition metals, including Fe(3+) and Cu(2+), and a signal line near g=2.00. After irradiation, a new splitting asymmetric spectrum with overall spectrum width ca. 10mT at g=2.004 was observed. The intensities of the signals at g=2.004 increased in proportion to the absorbed dose in samples under different storage conditions: fresh frozen royal jelly and dried royal jelly powder at room temperature. The signal intensity of the fresh frozen sample was stable after irradiation. One year after 10kGy irradiation of dried powder, the signal intensity was sevenfold greater than before irradiation, although the intensity continued to steadily decrease with time. This stable radiation-induced radical component was derived from the poorly soluble constituent of royal jelly. Copyright © 2013 Elsevier Ltd. All rights reserved.

Electron spin resonance identification di-carbon-related centers in irradiated silicon

NASA Astrophysics Data System (ADS)

Hayashi, S.; Saito, H.; Itoh, K. M.; Vlasenko, M. P.; Vlasenko, L. S.

2018-04-01

A previously unreported electron spin resonance (ESR) spectrum was found in γ-ray irradiated silicon by the detection of the change in microwave photoconductivity arising from spin-dependent recombination (SDR). In the specially prepared silicon crystals doped by 13C isotope, a well resolved hyperfine structure of SDR-ESR lines due to the interaction between electrons and two equivalent carbon atoms having nuclear spin I = 1/2 was observed. The Si-KU4 spectrum is described by spin Hamiltonian for spin S = 1 and of g and D tensors of orthorhombic symmetry with principal values g1 = 2.008, g2 = 2.002, and g3 =2.007; and D1 = ± 103 MHz, D2 = ∓170 MHz, and D3 = ± 67 MHz where axes 1, 2, and 3 are parallel to the [1 1 ¯ 0 ], [110], and [001] crystal axes, respectively. The hyperfine splitting arising from 13C nuclei is about 0.35 mT. A possible microstructure of the detect leading to the Si-KU4 spectrum is discussed.

The millimeter wave spectrum of methyl cyanate: a laboratory study and astronomical search in space ⋆,⋆⋆

PubMed Central

Kolesniková, L.; Alonso, J. L.; Bermúdez, C.; Alonso, E. R.; Tercero, B.; Cernicharo, J.; Guillemin, J.-C.

2016-01-01

Aims The recent discovery of methyl isocyanate (CH3NCO) in Sgr B2(N) and Orion KL makes methyl cyanate (CH3OCN) a potential molecule in the interstellar medium. The aim of this work is to fulfill the first requirement for its unequivocal identification in space, i.e. the availability of transition frequencies with high accuracy. Methods The room-temperature rotational spectrum of methyl cyanate was recorded in the millimeter wave domain from 130 to 350 GHz. All rotational transitions revealed A-E splitting owing to methyl internal rotation and were globally analyzed using the ERHAM program. Results The data set for the ground torsional state of methyl cyanate exceeds 700 transitions within J″ = 10 – 35 and Ka″=0−13 and newly derived spectroscopic constants reproduce the spectrum close to the experimental uncertainty. Spectral features of methyl cyanate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of methyl cyanate are provided. PMID:27721514

Spectroscopic Measurements of Hydrogen Ion Temperature During Divertor Recombination

NASA Astrophysics Data System (ADS)

Stotler, D. P.; Skinner, C. H.; Karney, C. F. F.

1998-11-01

We explore the possibility of using the neutral H_α spectral line profile to measure the ion temperature Ti in a recombining plasma. Since the H_α emissions due to recombination are larger than those due to other mechanisms, interference from non-recombining regions contributing to the chord integrated data is insignificant. A chord integrated, Doppler and Stark broadened H_α spectrum is simulated by the DEGAS 2 Monte Carlo neutral transport code(D. Stotler and C. Karney, Contrib. Plasma Phys.) 34, 392 (1994). using assumed plasma conditions. The application of a simple fitting procedure to this spectrum yields an average electron density ne and Ti consistent with the assumed plasma parameters if the spectrum is dominated by recombination from a region of modest ne variation. The interpretation of experimental data is complicated by Zeeman splitting and light reflection off surfaces. Ion temperature measurements by H_α spectroscopy appear feasible within the context of a model for the entire divertor plasma that takes these effects into account.

Classification of cognitive systems dedicated to data sharing

NASA Astrophysics Data System (ADS)

Ogiela, Lidia; Ogiela, Marek R.

2017-08-01

In this paper will be presented classification of new cognitive information systems dedicated to cryptographic data splitting and sharing processes. Cognitive processes of semantic data analysis and interpretation, will be used to describe new classes of intelligent information and vision systems. In addition, cryptographic data splitting algorithms and cryptographic threshold schemes will be used to improve processes of secure and efficient information management with application of such cognitive systems. The utility of the proposed cognitive sharing procedures and distributed data sharing algorithms will be also presented. A few possible application of cognitive approaches for visual information management and encryption will be also described.

Photoelectron spectrum of PrO{sup −}

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

Kafader, Jared O.; Ray, Manisha; Jarrold, Caroline Chick

The photoelectron (PE) spectrum of PrO{sup −} exhibits a short 835 ± 20 cm{sup −1} vibrational progression of doublets (210 ± 30 cm{sup −1} splitting) assigned to transitions from the 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s}{sup 2} Ω = 4 anion ground state to the 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s} Ω = 3.5 and 4.5 neutral states. This assignment is analogous to that of the recently reported PE spectrum of CeO{sup −}, though the 82 cm{sup −1} splitting between the 4f [{sup 2}F{sub 2.5}] σ{sub 6s} Ω = 2 and Ω = 3 CeO neutral states couldmore » not be resolved [Ray et al., J. Chem. Phys. 142, 064305 (2015)]. The origin of the transition to the Ω = 3.5 neutral ground state is 0.96 ± 0.01 eV, which is the adiabatic electron affinity of PrO. Density functional theory calculations on the anion and neutral molecules support the assignment. The appearance of multiple, irregularly spaced and low-intensity features observed ca. 1 eV above the ground state cannot be reconciled with low-lying electronic states of PrO that are accessible via one-electron detachment. However, neutral states correlated with the 4f{sup 2} [{sup 3}H{sub 4}] 5d superconfiguration are predicted to be approximately 1 eV above the 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s} Ω = 3.5 neutral ground state, leading to the assignment of these features to shake-up transitions to the excited neutral states. Based on tentative hot band transition assignments, the term energy of the previously unobserved 4f{sup 2} [{sup 3}H{sub 4}] σ{sub 6s} Ω = 2.5 neutral state is determined to be 1840 ± 110 cm{sup −1}.« less

Method for increasing steam decomposition in a coal gasification process

DOEpatents

Wilson, Marvin W.

1988-01-01

The gasification of coal in the presence of steam and oxygen is significantly enhanced by introducing a thermochemical water-splitting agent such as sulfuric acid, into the gasifier for decomposing the steam to provide additional oxygen and hydrogen usable in the gasification process for the combustion of the coal and enrichment of the gaseous gasification products. The addition of the water-splitting agent into the gasifier also allows for the operation of the reactor at a lower temperature.

Method for increasing steam decomposition in a coal gasification process

DOEpatents

Wilson, M.W.

1987-03-23

The gasification of coal in the presence of steam and oxygen is significantly enhanced by introducing a thermochemical water- splitting agent such as sulfuric acid, into the gasifier for decomposing the steam to provide additional oxygen and hydrogen usable in the gasification process for the combustion of the coal and enrichment of the gaseous gasification products. The addition of the water-splitting agent into the gasifier also allows for the operation of the reactor at a lower temperature.

Postscript: Split Spatial Attention? The Data Remain Difficult to Interpret

ERIC Educational Resources Information Center

Jans, Bert; Peters, Judith C.; De Weerd, Peter

2010-01-01

A growing number of studies claim that spatial attention can be split "on demand" into several, segregated foci of enhanced processing. Intrigued by the theoretical ramifications of this proposal, we analyzed 19 relevant sets of experiments using four methodological criteria. We typically found several methodological limitations in each study that…

Detection of the valvular split within the second heart sound using the reassigned smoothed pseudo Wigner–Ville distribution

PubMed Central

2013-01-01

Background In this paper, we developed a novel algorithm to detect the valvular split between the aortic and pulmonary components in the second heart sound which is a valuable medical information. Methods The algorithm is based on the Reassigned smoothed pseudo Wigner–Ville distribution which is a modified time–frequency distribution of the Wigner–Ville distribution. A preprocessing amplitude recovery procedure is carried out on the analysed heart sound to improve the readability of the time–frequency representation. The simulated S2 heart sounds were generated by an overlapping frequency modulated chirp–based model at different valvular split durations. Results Simulated and real heart sounds are processed to highlight the performance of the proposed approach. The algorithm is also validated on real heart sounds of the LGB–IRCM (Laboratoire de Génie biomédical–Institut de recherches cliniques de Montréal) cardiac valve database. The A2–P2 valvular split is accurately detected by processing the obtained RSPWVD representations for both simulated and real data. PMID:23631738

Reinforcement Learning Trees

PubMed Central

Zhu, Ruoqing; Zeng, Donglin; Kosorok, Michael R.

2015-01-01

In this paper, we introduce a new type of tree-based method, reinforcement learning trees (RLT), which exhibits significantly improved performance over traditional methods such as random forests (Breiman, 2001) under high-dimensional settings. The innovations are three-fold. First, the new method implements reinforcement learning at each selection of a splitting variable during the tree construction processes. By splitting on the variable that brings the greatest future improvement in later splits, rather than choosing the one with largest marginal effect from the immediate split, the constructed tree utilizes the available samples in a more efficient way. Moreover, such an approach enables linear combination cuts at little extra computational cost. Second, we propose a variable muting procedure that progressively eliminates noise variables during the construction of each individual tree. The muting procedure also takes advantage of reinforcement learning and prevents noise variables from being considered in the search for splitting rules, so that towards terminal nodes, where the sample size is small, the splitting rules are still constructed from only strong variables. Last, we investigate asymptotic properties of the proposed method under basic assumptions and discuss rationale in general settings. PMID:26903687

Shot noise as a measure of the lifetime and energy splitting of Majorana bound states

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

Lü, Hai-Feng; Guo, Zhen; Ke, Sha-Sha

We propose a scheme to measure the lifetime and energy splitting of a pair of Majorana bound states at the ends of a superconducting nanowire by using the shot noise in a dynamical channel blockade system. A quantum dot is coupled to one end of the wire and connected with two electron reservoirs. It is found that a finite Majorana energy splitting tends to produce a super-Poissonian shot noise, while Majorana relaxation process relieves the dynamical channel blockade and suppresses the noise Fano factor. When the dot energy level locates in the middle of the gap of topological superconductor, themore » Fano factor is independent on Majorana lifetime and Majorana energy splitting is thus extracted. For a finite energy splitting, we could evaluate the Majorana relaxation rate from the suppression of Fano factor. Under a realistic condition, the expected resolution of Majorana energy splitting and its relaxation rate calculated from our model are about 1μeV and 0.01−1μeV, respectively.« less

Rotational characterization of methyl methacrylate: Internal dynamics and structure determination

NASA Astrophysics Data System (ADS)

Herbers, Sven; Wachsmuth, Dennis; Obenchain, Daniel A.; Grabow, Jens-Uwe

2018-01-01

Rotational constants, Watson's S centrifugal distortion coefficients, and internal rotation parameters of the two most stable conformers of methyl methacrylate were retrieved from the microwave spectrum. Splittings of rotational energy levels were caused by two non equivalent methyl tops. Constraining the centrifugal distortion coefficients and internal rotation parameters to the values of the main isotopologues, the rotational constants of all single substituted 13C and 18O isotopologues were determined. From these rotational constants the substitution structures and semi-empirical zero point structures of both conformers were precisely determined.

Noisy Spins and the Richardson-Gaudin Model

NASA Astrophysics Data System (ADS)

Rowlands, Daniel A.; Lamacraft, Austen

2018-03-01

We study a system of spins (qubits) coupled to a common noisy environment, each precessing at its own frequency. The correlated noise experienced by the spins implies long-lived correlations that relax only due to the differing frequencies. We use a mapping to a non-Hermitian integrable Richardson-Gaudin model to find the exact spectrum of the quantum master equation in the high-temperature limit and, hence, determine the decay rate. Our solution can be used to evaluate the effect of inhomogeneous splittings on a system of qubits coupled to a common bath.

The hydrogen tunneling splitting in malonaldehyde: A full-dimensional time-independent quantum mechanical method

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

Wu, Feng; Ren, Yinghui; Bian, Wensheng, E-mail: bian@iccas.ac.cn

The accurate time-independent quantum dynamics calculations on the ground-state tunneling splitting of malonaldehyde in full dimensionality are reported for the first time. This is achieved with an efficient method developed by us. In our method, the basis functions are customized for the hydrogen transfer process which has the effect of greatly reducing the size of the final Hamiltonian matrix, and the Lanczos method and parallel strategy are used to further overcome the memory and central processing unit time bottlenecks. The obtained ground-state tunneling splitting of 24.5 cm{sup −1} is in excellent agreement with the benchmark value of 23.8 cm{sup −1}more » computed with the full-dimensional, multi-configurational time-dependent Hartree approach on the same potential energy surface, and we estimate that our reported value has an uncertainty of less than 0.5 cm{sup −1}. Moreover, the role of various vibrational modes strongly coupled to the hydrogen transfer process is revealed.« less

Computer program for analysis of split-Stirling-cycle cryogenic coolers

NASA Technical Reports Server (NTRS)

Brown, M. T.; Russo, S. C.

1983-01-01

A computer program for predicting the detailed thermodynamic performance of split-Stirling-cycle refrigerators has been developed. The mathematical model includes the refrigerator cold head, free-displacer/regenerator, gas transfer line, and provision for modeling a mechanical or thermal compressor. To allow for dynamic processes (such as aerodynamic friction and heat transfer) temperature, pressure, and mass flow rate are varied by sub-dividing the refrigerator into an appropriate number of fluid and structural control volumes. Of special importance to modeling of cryogenic coolers is the inclusion of real gas properties, and allowance for variation of thermo-physical properties such as thermal conductivities, specific heats and viscosities, with temperature and/or pressure. The resulting model, therefore, comprehensively simulates the split-cycle cooler both spatially and temporally by reflecting the effects of dynamic processes and real material properties.

Photon merging and splitting in electromagnetic field inhomogeneities

NASA Astrophysics Data System (ADS)

Gies, Holger; Karbstein, Felix; Seegert, Nico

2016-04-01

We investigate photon merging and splitting processes in inhomogeneous, slowly varying electromagnetic fields. Our study is based on the three-photon polarization tensor following from the Heisenberg-Euler effective action. We put special emphasis on deviations from the well-known constant field results, also revisiting the selection rules for these processes. In the context of high-intensity laser facilities, we analytically determine compact expressions for the number of merged/split photons as obtained in the focal spots of intense laser beams. For the parameter range of typical petawatt class laser systems as pump and probe, we provide estimates for the numbers of signal photons attainable in an actual experiment. The combination of frequency upshifting, polarization dependence and scattering off the inhomogeneities renders photon merging an ideal signature for the experimental exploration of nonlinear quantum vacuum properties.

Film and television in Croatia today: production, new technologies and the relationship with visual anthropology.

PubMed

Svilicić, Niksa; Vidacković, Zlatko

2013-03-01

This paper seeks to explain some of the most important recent production and technological changes that have affected the relationship between television and film, especially in Croatia, from the aspect of the development of visual anthropology. In the production segment, special attention was given to the role of Croatian television stations in the production of movies, "splitting" the movies into mini-series, interrupting movies with commercial breaks, and to television movies turned into feature films. This paper tries to perceive and define the structure of methodical processes of visual anthropology (reactive process). The development of photographic and film technology and the events which led to the rapid development of visual culture also point to the inseparable duality of observing visual anthropology within reactive and proactive processes, which are indirectly closely related to the technical aspects of these processes. Defining the technical aspect of visual anthropology as such "service" necessarily interferes with the author's approach in the domain of the script and direction related procedures during pre-production, on the field and during post-production of the movie. The author's approach is important because in dependence on it, the desired spectrum of information "output", susceptible to subsequent scientific analysis, is achieved. Lastly, another important segment is the "distributive-technological process" because, regardless of the approach to the anthropologically relevant phenomenon which is being dealt with in an audio-visual piece of work, it is essential that the work be presented and viewed adequately.

Internal rotation in halogenated toluenes: Rotational spectrum of 2,3-difluorotoluene

NASA Astrophysics Data System (ADS)

Nair, K. P. Rajappan; Herbers, Sven; Grabow, Jens-Uwe; Lesarri, Alberto

2018-07-01

The microwave rotational spectrum of 2,3-difluorotoluene has been studied by pulsed supersonic jet using Fourier transform microwave spectroscopy. The tunneling splitting due to the methyl internal rotation in the ground torsional state could be unambiguously identified and the three-fold (V3) potential barrier hindering the internal rotation of the methyl top was determined as 2518.70(15) J/mol. The ground-state rotational parameters for the parent and seven 13C isotopic species in natural abundance were determined with high accuracy, including all quartic centrifugal distortion constants. The molecular structure was derived using the substitution (rs) method. From the rotational constants of the different isotopic species the rs structure as well as the r0 structure was determined. Supporting ab initio (MP2) and DFT (B3LYP) calculations provided comparative values for the potential barrier and molecular parameters.

Heavy-Meson Spectrum Tests of the Oktay--Kronfeld Action

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

Bailey, Jon A.; Jang, Yong-Chull; Lee, Weonjong

2014-11-07

We present heavy-meson spectrum results obtained using the Oktay--Kronfeld (OK) action on MILC asqtad lattices. The OK action was designed to improve the heavy-quark action of the Fermilab formulation, such that heavy-quark discretization errors are reduced. The OK action includes dimension-6 and -7 operators necessary for tree-level matching to QCD through ordermore » $$\\mathrm{O}(\\Lambda^3/m_Q^3)$$ for heavy-light mesons and $$\\mathrm{O}(v^6)$$ for quarkonium, or, equivalently, through $$\\mathrm{O}(a^2)$$ with some $$\\mathrm{O}(a^3)$$ terms with Symanzik power counting. To assess the improvement, we extend previous numerical tests with heavy-meson masses by analyzing data generated on a finer ($$a \\approx 0.12\\;$$fm) lattice with the correct tadpole factors for the $$c_5$$ term in the action. We update the analyses of the inconsistency parameter and the hyperfine splittings for the rest and kinetic masses.« less

A Decentralized Eigenvalue Computation Method for Spectrum Sensing Based on Average Consensus

NASA Astrophysics Data System (ADS)

Mohammadi, Jafar; Limmer, Steffen; Stańczak, Sławomir

2016-07-01

This paper considers eigenvalue estimation for the decentralized inference problem for spectrum sensing. We propose a decentralized eigenvalue computation algorithm based on the power method, which is referred to as generalized power method GPM; it is capable of estimating the eigenvalues of a given covariance matrix under certain conditions. Furthermore, we have developed a decentralized implementation of GPM by splitting the iterative operations into local and global computation tasks. The global tasks require data exchange to be performed among the nodes. For this task, we apply an average consensus algorithm to efficiently perform the global computations. As a special case, we consider a structured graph that is a tree with clusters of nodes at its leaves. For an accelerated distributed implementation, we propose to use computation over multiple access channel (CoMAC) as a building block of the algorithm. Numerical simulations are provided to illustrate the performance of the two algorithms.

Effects of an electric field on the electronic and optical properties of zigzag boron nitride nanotubes

NASA Astrophysics Data System (ADS)

Chegel, Raad; Behzad, Somayeh

2011-02-01

We have investigated the electro-optical properties of zigzag BNNTs, under an external electric field, using the tight binding approximation. It is found that an electric field modifies the band structure and splits the band degeneracy. Also the large electric strength leads to coupling the neighbor subbands which these effects reflect in the DOS and JDOS spectrum. It has been shown that, unlike CNTs, the band gap of BNNTs can be reduced linearly by applying a transverse external electric field. Also we show that the larger diameter tubes are more sensitive than small ones. The semiconducting metallic transition can be achieved through increasing the applied fields. The number and position of peaks in the JDOS spectrum are dependent on electric field strength. It is found that at a high electric field, the two lowest subbands are oscillatory with multiple nodes at the Fermi level.

Representation of high frequency Space Shuttle data by ARMA algorithms and random response spectra

NASA Technical Reports Server (NTRS)

Spanos, P. D.; Mushung, L. J.

1990-01-01

High frequency Space Shuttle lift-off data are treated by autoregressive (AR) and autoregressive-moving-average (ARMA) digital algorithms. These algorithms provide useful information on the spectral densities of the data. Further, they yield spectral models which lend themselves to incorporation to the concept of the random response spectrum. This concept yields a reasonably smooth power spectrum for the design of structural and mechanical systems when the available data bank is limited. Due to the non-stationarity of the lift-off event, the pertinent data are split into three slices. Each of the slices is associated with a rather distinguishable phase of the lift-off event, where stationarity can be expected. The presented results are rather preliminary in nature; it is aimed to call attention to the availability of the discussed digital algorithms and to the need to augment the Space Shuttle data bank as more flights are completed.

Lattice dynamics of Cs2NaYbF6 and Cs2NaYF6 elpasolites: Ab initio calculation

NASA Astrophysics Data System (ADS)

Chernyshev, V. A.; Petrov, V. P.; Nikiforov, A. E.; Zakir'yanov, D. O.

2015-06-01

The ab initio calculations of the crystal structure and the phonon spectrum of Cs2NaYbF6 and Cs2NaYF6 crystals with the elpasolite structure have been performed. The frequencies and types of fundamental vibrations have been determined. The calculations have been performed in the framework of the density functional theory using the molecular orbital method with hybrid functionals in the CRYSTAL09 program developed for the simulation of periodic structures. The outer 5 s and 5 p shells of the rare-earth ion have been described in Gaussian-type basis sets. The influence of inner shells, including 4 f electron shells, on the outer shells has been described using the pseudopotential. It has been shown that this approach allows the description of the phonon spectrum with the inclusion of the splitting of the longitudinal and transverse optical modes.

A HeI photoelectron spectrum of the [Al(CH 3) 3] 2 dimer

NASA Astrophysics Data System (ADS)

Wang, Dianxun; Qian, Ximei; Zheng, Shijun; Shi, Yizhong

1997-10-01

The HeI photoelectron spectrum (PES) of the [Al(CH 3) 3] 2 dimer is recorded for the first time. To assign the PES bands, an ab initio SCF MO calculation for the dimer has also been performed. The four splitting peaks of the first PE band are respectively designated to electron ionization of the four frontier 8b u, 13a g, 7b g, and 7b u orbitals of the dimer. They originate from the recombination of the two HOMO (5e') of the two monomers in the forming of the dimer. That is to say, during the formation of the dimer from the two monomers, the reduction of molecular symmetry (from the C 3h symmetry of the monomer to the C 2h symmetry of the dimer) leads to the undegeneration of the degenerate orbitals.

Charge transfer transitions in optical spectra of NicMg1-cO oxides

NASA Astrophysics Data System (ADS)

Churmanov, V. N.; Sokolov, V. I.; Pustovarov, V. A.; Gruzdev, N. B.; Uimin, M. A.; Byzov, I. V.; Druzhinin, A. V.; Korolyov, A. V.; Kim, G. A.; Zatsepin, A. F.; Kuznetsova, J. A.

2017-04-01

Radiative recombination with charge transfer was observed in NicMg1-cO (c = 0.008) oxides over the 8-300 K temperature range. This recombination occurs as a result of strong hybridization of the Ni2+ ion 3d-states and the band states. The charge transfer radiation excitation spectrum shows vibrational LO repeats of two exciton lines having charge transfer energy intervals of about 35 meV. The NiO nanocrystal absorption spectrum shows two weak peaks with energies of 3.510 and 3.543 eV, which are highly dependent on temperature. They are interpreted as charge transfer excitons at the edge of NiO fundamental absorption. The distance between the charge transfer exciton lines in the NicMg1-cO oxide spectra are caused by spin-orbit splitting of the valence band peak that was formed by the p-states of the oxygen ion.

Contribution of double scattering to structural coloration in quasiordered nanostructures of bird feathers

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

Noh, Heeso; Liew, Seng Fatt; Saranathan, Vinodkumar

2010-07-28

We measured the polarization- and angle-resolved optical scattering and reflection spectra of the quasiordered nanostructures in the bird feather barbs. In addition to the primary peak that originates from single scattering, we observed a secondary peak which exhibits depolarization and distinct angular dispersion. We explained the secondary peak in terms of double scattering, i.e., light is scattered successively twice by the structure. The two sequential single-scattering events are considered uncorrelated. Using the Fourier power spectra of the nanostructures obtained from the small-angle x-ray scattering experiment, we calculated the double scattering of light in various directions. The double-scattering spectrum is broadermore » than the single-scattering spectrum, and it splits into two subpeaks at larger scattering angle. The good agreement between the simulation results and the experimental data confirms that double scattering of light makes a significant contribution to the structural color.« less

Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides.

PubMed

Drees, Y; Li, Z W; Ricci, A; Rotter, M; Schmidt, W; Lamago, D; Sobolev, O; Rütt, U; Gutowski, O; Sprung, M; Piovano, A; Castellan, J P; Komarek, A C

2014-12-23

The magnetic excitations in the cuprate superconductors might be essential for an understanding of high-temperature superconductivity. In these cuprate superconductors the magnetic excitation spectrum resembles an hour-glass and certain resonant magnetic excitations within are believed to be connected to the pairing mechanism, which is corroborated by the observation of a universal linear scaling of superconducting gap and magnetic resonance energy. So far, charge stripes are widely believed to be involved in the physics of hour-glass spectra. Here we study an isostructural cobaltate that also exhibits an hour-glass magnetic spectrum. Instead of the expected charge stripe order we observe nano phase separation and unravel a microscopically split origin of hour-glass spectra on the nano scale pointing to a connection between the magnetic resonance peak and the spin gap originating in islands of the antiferromagnetic parent insulator. Our findings open new ways to theories of magnetic excitations and superconductivity in cuprate superconductors.

Antiferromagnetic Ordering in Quasi-Triangular Localized Spin System, β'-Et2Me2P[Pd(dmit)2]2, Studied by 13C NMR

NASA Astrophysics Data System (ADS)

Otsuka, Kei; Iikubo, Hideaki; Kogure, Takayuki; Takano, Yoshiki; Hiraki, Ko-ichi; Takahashi, Toshihiro; Cui, Hengbo; Kato, Reizo

2014-05-01

We performed 13C NMR measurements of a selectively 13C isotope-labeled single-crystal sample of a frustrated spin system, β'-Et2Me2P[Pd(dmit)2]2. A long-range antiferromagnetic (AF) ordering below 17 K was confirmed by the observation of NMR spectrum broadening and well split resonance lines at lower temperatures. NMR spectra in the AF state can be well explained by a two sublattice model. From the analysis of the angular dependence of the NMR spectrum, we clarified the magnetic structure in the AF state, where the easy and hard axes are the crystallographic c*- and b-axes, respectively, and the effective localized moments are quite small, ˜0.28 μB/dimer. This suggests a strong quantum fluctuation effect due to magnetic frustrations in a quasi-triangular spin-1/2 system.

Antimicrobial-impregnated dressing combined with negative-pressure wound therapy increases split-thickness skin graft engraftment: a simple effective technique.

PubMed

Wu, Cheng-Chun; Chew, Khong-Yik; Chen, Chien-Chang; Kuo, Yur-Ren

2015-01-01

Immobilization and adequate surface contact to wounds are critical for skin graft take. Techniques such as the tie-over dressing, cotton bolster, and vacuum-assisted closure are used to address this, but each has its limitations. This study is designed to assess the effect of antimicrobial-impregnated dressing (AMD) combined with negative-pressure wound therapy (NPWT) on skin graft survival. Retrospective case-control study : Patients with chronic or contaminated wounds treated with split-thickness skin graft. A broad spectrum of wounds was included, from causes such as trauma, burns, chronic diabetic ulcers, and infection. Antimicrobial-impregnated dressing, which contains 0.2% polyhexamethylene biguanide, with NPWT MAIN OUTCOME MEASURE:: Success of skin graft : In the AMD group, all skin grafts achieved 100% take without secondary intervention. No infection or graft failure was observed in any patients, and no complications, such as hematoma or seroma formation, were noted, although in the control group partial loss of skin grafts was noted in 3 patients. Infection and inadequate immobilization were thought to be the main reasons. There were no hematoma or seroma formations in the control group. Use of an AMD dressing with NPWT after split-thickness skin grafting can be an effective method to ensure good graft to wound contact and enhances skin graft take in chronic and contaminated wounds.

Localization enhanced and degraded topological order in interacting p -wave wires

NASA Astrophysics Data System (ADS)

Kells, G.; Moran, N.; Meidan, D.

2018-02-01

We numerically study the effect of disorder on the stability of the many-body zero mode in a Kitaev chain with local interactions. Our numerical procedure allows us to resolve the position space and multiparticle structure of the zero modes, as well as providing estimates for the mean energy splitting between pairs of states of opposite fermion parity, over the full many-body spectrum. We find that the parameter space of a clean system can be divided into regions where interaction induced decay transitions are suppressed (region I) and where they are not (region II). In region I we observe that disorder has an adverse effect on the zero mode, which extends further into the bulk and is accompanied by an increased energy splitting between pairs of states of opposite parity. Conversely region II sees a more intricate effect of disorder, showing an enhancement of localization at the system's end accompanied by a reduction in the mean pairwise energy splitting. We discuss our results in the context of the many-body localization (MBL). We show that while the mechanism that drives the MBL transition also contributes to the fock-space localization of the many-body zero modes, measures that characterize the degree of MBL do not necessarily correlate with an enhancement of the zero mode or an improved stability of the topological region.

Modulation of auroras by Pc5 pulsations in the dawn sector in association with reappearance of energetic particles at geosynchronous orbit

NASA Astrophysics Data System (ADS)

Saka, O.; Hayashi, K.; Klimushkin, D. Yu.; Mager, P. N.

2014-04-01

Geomagnetic Pc5 pulsations were observed in the dawn sector of the auroral zone on 17 January 1994 in association with increased energetic ion fluxes at geosynchronous orbit 10 min after the Pi2 onset. The characteristic properties of auroras associated with these pulsations were studied using movies taken by an all-sky imager. It was found that a pulsating aurora (PA) can be an optical manifestation of the Pc5 waves by a strong poloidal component observed with ground-based magnetometers. Goes7 observations showed compressional pulsations with the same period which can be attributed to the influence of the finite pressure of plasma and field line curvature on the poloidally polarized Alfvén waves. These poloidal pulsations may be generated by the ion injection observed with the LANL 1989-046 satellite. Two auroral arcs were observed north of the PA with optical features characteristic for the toroidal field line resonances: strong localization across L-shells, 180° phase change across the resonance, poleward phase propagation. Thus the Pc5 oscillations split into the toroidal and poloidal mode and oscillated coherently at latitudes from 62°N to 70°N. This study provides observational evidence of polarization splitting of the Alfven oscillation spectrum. Such a polarization splitting would occur in association with the reappearance of the energetic particles at geosynchronous orbit.

Redirection and Splitting of Sound Waves by a Periodic Chain of Thin Perforated Cylindrical Shells

NASA Astrophysics Data System (ADS)

Bozhko, Andrey; Sánchez-Dehesa, José; Cervera, Francisco; Krokhin, Arkadii

2017-06-01

The scattering of sound by finite and infinite chains of equally spaced perforated metallic cylindrical shells in an ideal (inviscid) and viscous fluid is theoretically studied using rigorous analytical and numerical approaches. Because of perforations, a chain of thin shells is practically transparent for sound within a wide range of frequencies. It is shown that strong scattering and redirection of sound by 90° may occur only for a discrete set of frequencies (Wood's anomalies) where the leaky eigenmodes are excited. The spectrum of eigenmodes consists of antisymmetric and symmetric branches with normal and anomalous dispersion, respectively. The antisymmetric eigenmode turns out to be a deaf mode, since it cannot be excited at normal incidence. However, at slightly oblique incidence, both modes can be resonantly excited at different but close frequencies. The symmetric mode, due to its anomalous dispersion, scatters sound in the "wrong" direction. This property may find an application for the splitting of the two resonant harmonics of the incoming signal into two beams propagating along the chain in the opposite directions. A chain of perforated cylinders may also be used as a passive antenna that detects the direction to the incoming signal by measuring the frequencies of the waves excited in the chain. Calculations are presented for aluminum shells in viscous air where the effects of anomalous scattering, redirection, and signal splitting are well manifested.

Sharp phase variations from the plasmon mode causing the Rabi-analogue splitting

NASA Astrophysics Data System (ADS)

Wang, Yujia; Sun, Chengwei; Gan, Fengyuan; Li, Hongyun; Gong, Qihuang; Chen, Jianjun

2017-06-01

The Rabi-analogue splitting in nanostructures resulting from the strong coupling of different resonant modes is of importance for lasing, sensing, switching, modulating, and quantum information processes. To give a clearer physical picture, the phase analysis instead of the strong coupling is provided to explain the Rabi-analogue splitting in the Fabry-Pérot (FP) cavity, of which one end mirror is a metallic nanohole array and the other is a thin metal film. The phase analysis is based on an analytic model of the FP cavity, in which the reflectance and the reflection phase of the end mirrors are dependent on the wavelength. It is found that the Rabi-analogue splitting originates from the sharp phase variation brought by the plasmon mode in the FP cavity. In the experiment, the Rabi-analogue splitting is realized in the plasmonic-photonic coupling system, and this splitting can be continually tuned by changing the length of the FP cavity. These experimental results agree well with the analytic and simulation data, strongly verifying the phase analysis based on the analytic model. The phase analysis presents a clear picture to understand the working mechanism of the Rabi-analogue splitting; thus, it may facilitate the design of the plasmonic-photonic and plasmonic-plasmonic coupling systems.

"Split Cast Mounting: Review and New Technique".

PubMed

Gundawar, S M; Pande, Neelam A; Jaiswal, Priti; Radke, U M

2014-12-01

For the fabrication of a prosthesis, the Prosthodontist meticulously performs all the steps. The laboratory technician then make every effort/strives to perform the remaining lab procedures. However when the processed dentures are remounted on the articulator, some changes are seen. These changes may be divided into two categories: Pre-insertion and post-insertion changes, which deal with the physical properties of the materials involved (Parker, J Prosthet Dent 31:335-342, 1974). Split cast mounting is the method of mounting casts on the articulator. It is essentially a maxillary cast constructed in two parts with a horizontal division. The procedure allows for the verification of the accuracy of the initial mounting and the ease of removal and replacement of the cast. This provides a precise means of correcting the changes in occlusion occurring as a result of the processing technique (Nogueira et al., J Prosthet Dent 91:386-388, 2004). Instability of the split mounting has always been a problem to the Prosthodontist thereby limiting its use. There are various materials mentioned in the literature. The new technique by using Dowel pins and twill thread is very easy, cheaper and simple way to stabilize the split mounting. It is useful and easy in day to day laboratory procedures. The article presents different methods of split cast mounting and the new procedure using easily available materials in prosthetic laboratory.

Getting into Teams in Physical Education and Exclusion Processes among Students

ERIC Educational Resources Information Center

Grimminger, Elke

2014-01-01

Although splitting up a class into teams is a consistent didactical element in physical education (PE), it is under-investigated in terms of how students handle the social dynamics in these situations. Therefore, the present study examines the strategies of exclusion as markers for non-recognition when students are split up into teams/pairs. The…

Secure Communications in CIoT Networks with a Wireless Energy Harvesting Untrusted Relay

PubMed Central

Hu, Hequn; Liao, Xuewen

2017-01-01

The Internet of Things (IoT) represents a bright prospect that a variety of common appliances can connect to one another, as well as with the rest of the Internet, to vastly improve our lives. Unique communication and security challenges have been brought out by the limited hardware, low-complexity, and severe energy constraints of IoT devices. In addition, a severe spectrum scarcity problem has also been stimulated by the use of a large number of IoT devices. In this paper, cognitive IoT (CIoT) is considered where an IoT network works as the secondary system using underlay spectrum sharing. A wireless energy harvesting (EH) node is used as a relay to improve the coverage of an IoT device. However, the relay could be a potential eavesdropper to intercept the IoT device’s messages. This paper considers the problem of secure communication between the IoT device (e.g., sensor) and a destination (e.g., controller) via the wireless EH untrusted relay. Since the destination can be equipped with adequate energy supply, secure schemes based on destination-aided jamming are proposed based on power splitting (PS) and time splitting (TS) policies, called intuitive secure schemes based on PS (Int-PS), precoded secure scheme based on PS (Pre-PS), intuitive secure scheme based on TS (Int-TS) and precoded secure scheme based on TS (Pre-TS), respectively. The secure performances of the proposed schemes are evaluated through the metric of probability of successfully secure transmission (PSST), which represents the probability that the interference constraint of the primary user is satisfied and the secrecy rate is positive. PSST is analyzed for the proposed secure schemes, and the closed form expressions of PSST for Pre-PS and Pre-TS are derived and validated through simulation results. Numerical results show that the precoded secure schemes have better PSST than the intuitive secure schemes under similar power consumption. When the secure schemes based on PS and TS polices have similar PSST, the average transmit power consumption of the secure scheme based on TS is lower. The influences of power splitting and time slitting ratios are also discussed through simulations. PMID:28869540

Silicon technology compatible photonic molecules for compact optical signal processing

NASA Astrophysics Data System (ADS)

Barea, Luis A. M.; Vallini, Felipe; Jarschel, Paulo F.; Frateschi, Newton C.

2013-11-01

Photonic molecules (PMs) based on multiple inner coupled microring resonators allow to surpass the fundamental constraint between the total quality factor (QT), free spectral range (FSR), and resonator size. In this work, we use a PM that presents doublets and triplets resonance splitting, all with high QT. We demonstrate the use of the doublet splitting for 34.2 GHz signal extraction by filtering the sidebands of a modulated optical signal. We also demonstrate that very compact optical modulators operating 2.75 times beyond its resonator linewidth limit may be obtained using the PM triplet splitting, with separation of ˜55 GHz.

Novel approach using DNA-RNA hybrids in RNA nanotechnology | Center for Cancer Research

Cancer.gov

Developing simple approaches to detect interactions, modifications, and cellular locations of macromolecules is essential for understanding biochemical processes. The use of protein fragment complementation assays, also called split-protein systems, is a highly sensitive approach for studying protein interactions in biological systems. In this approach, functional proteins are split into non-functional fragments, and when attached to possible interacting partners, can reassemble and become functional again. Use of split-protein assays can establish differences between a healthy and a diseased state in the cell as well as determine the outcome of a therapeutic intervention.

Pair cascades in the magnetospheres of strongly magnetized neutron stars

NASA Astrophysics Data System (ADS)

Medin, Zach; Lai, Dong

2010-08-01

We present numerical simulations of electron-positron pair cascades in the magnetospheres of magnetic neutron stars for a wide range of surface fields (Bp = 1012-1015 G), rotation periods (0.1-10 s) and field geometries. This has been motivated by the discovery in recent years of a number of radio pulsars with inferred magnetic fields comparable to those of magnetars. Evolving the cascade generated by a primary electron or positron after it has been accelerated in the inner gap of the magnetosphere, we follow the spatial development of the cascade until the secondary photons and electron-positron pairs leave the magnetosphere, and we obtain the pair multiplicity and the energy spectra of the cascade pairs and photons under various conditions. Going beyond previous works, which were restricted to weaker fields (B <~ afew × 1012 G), we have incorporated in our simulations detailed treatments of physical processes that are potentially important (especially in the high-field regime) but were either neglected or crudely treated before, including photon splitting with the correct selection rules for photon polarization modes, one-photon pair production into low Landau levels for the e+/-, and resonant inverse Compton scattering from polar cap hotspots. We find that even for B >> BQ = 4 × 1013 G, photon splitting has a small effect on the multiplicity of the cascade since a majority of the photons in the cascade cannot split. One-photon decay into e+ e- pairs at low Landau levels, however, becomes the dominant pair production channel when B >~ 3 × 1012 G; this tends to suppress synchrotron radiation so that the cascade can develop only at a larger distance from the stellar surface. Nevertheless, we find that the total number of pairs and their energy spectrum produced in the cascade depend mainly on the polar cap voltage BpP-2, and are weakly dependent on Bp (and P) alone. We discuss the implications of our results for the radio pulsar death line and for the hard X-ray emission from magnetized neutron stars.

A Method to Analyze and Optimize the Load Sharing of Split Path Transmissions

NASA Technical Reports Server (NTRS)

Krantz, Timothy L.

1996-01-01

Split-path transmissions are promising alternatives to the common planetary transmissions for rotorcraft. Heretofore, split-path designs proposed for or used in rotorcraft have featured load-sharing devices that add undesirable weight and complexity to the designs. A method was developed to analyze and optimize the load sharing in split-path transmissions without load-sharing devices. The method uses the clocking angle as a design parameter to optimize for equal load sharing. In addition, the clocking angle tolerance necessary to maintain acceptable load sharing can be calculated. The method evaluates the effects of gear-shaft twisting and bending, tooth bending, Hertzian deformations within bearings, and movement of bearing supports on load sharing. It was used to study the NASA split-path test gearbox and the U.S. Army's Comanche helicopter main rotor gearbox. Acceptable load sharing was found to be achievable and maintainable by using proven manufacturing processes. The analytical results compare favorably to available experimental data.

Layer Splitting in a Complex Plasma

NASA Astrophysics Data System (ADS)

Smith, Bernard; Hyde, Truell; Matthews, Lorin; Johnson, Megan; Cook, Mike; Schmoke, Jimmy

2009-11-01

Dust particle clouds are found in most plasma processing environments and many astrophysical environments. Dust particles suspended within such plasmas often acquire an electric charge from collisions with free electrons in the plasma. Depending upon the ratio of interparticle potential energy to average kinetic energy, charged dust particles can form a gaseous, liquid or crystalline structure with short to longer range ordering. An interesting facet of complex plasma behavior is that particle layers appear to split as the DC bias is increased. This splitting of layers points to a phase transition differing from the normal phase transitions found in two-dimensional solids. In 1993, Dubin noted that as the charged particle density of an initially two-dimensional Coulomb crystal increases the system's layers split at specific charge densities. This work modeled ions in a Paul or Penning trap, but may be applicable to dusty plasma systems as well. This work will discuss this possibility along with splitting observed in the CASPER GEC rf Reference Cell at specific pressures and powers.

Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

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

Skytt, P.; Glans, P.; Gunnelin, K.

1997-04-01

The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons couldmore » not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.« less

Electroweak splitting functions and high energy showering

NASA Astrophysics Data System (ADS)

Chen, Junmou; Han, Tao; Tweedie, Brock

2017-11-01

We derive the electroweak (EW) collinear splitting functions for the Standard Model, including the massive fermions, gauge bosons and the Higgs boson. We first present the splitting functions in the limit of unbroken SU(2) L × U(1) Y and discuss their general features in the collinear and soft-collinear regimes. These are the leading contributions at a splitting scale ( k T ) far above the EW scale ( v). We then systematically incorporate EW symmetry breaking (EWSB), which leads to the emergence of additional "ultra-collinear" splitting phenomena and naive violations of the Goldstone-boson Equivalence Theorem. We suggest a particularly convenient choice of non-covariant gauge (dubbed "Goldstone Equivalence Gauge") that disentangles the effects of Goldstone bosons and gauge fields in the presence of EWSB, and allows trivial book-keeping of leading power corrections in v/ k T . We implement a comprehensive, practical EW showering scheme based on these splitting functions using a Sudakov evolution formalism. Novel features in the implementation include a complete accounting of ultra-collinear effects, matching between shower and decay, kinematic back-reaction corrections in multi-stage showers, and mixed-state evolution of neutral bosons ( γ/ Z/ h) using density-matrices. We employ the EW showering formalism to study a number of important physical processes at O (1-10 TeV) energies. They include (a) electroweak partons in the initial state as the basis for vector-boson-fusion; (b) the emergence of "weak jets" such as those initiated by transverse gauge bosons, with individual splitting probabilities as large as O (35%); (c) EW showers initiated by top quarks, including Higgs bosons in the final state; (d) the occurrence of O (1) interference effects within EW showers involving the neutral bosons; and (e) EW corrections to new physics processes, as illustrated by production of a heavy vector boson ( W ') and the subsequent showering of its decay products.

Constraints on mirror models of dark matter from observable neutron-mirror neutron oscillation

NASA Astrophysics Data System (ADS)

Mohapatra, Rabindra N.; Nussinov, Shmuel

2018-01-01

The process of neutron-mirror neutron oscillation, motivated by symmetric mirror dark matter models, is governed by two parameters: n -n‧ mixing parameter δ and n -n‧ mass splitting Δ. For neutron mirror neutron oscillation to be observable, the splitting between their masses Δ must be small and current experiments lead to δ ≤ 2 ×10-27 GeV and Δ ≤10-24 GeV. We show that in mirror universe models where this process is observable, this small mass splitting constrains the way that one must implement asymmetric inflation to satisfy the limits of Big Bang Nucleosynthesis on the number of effective light degrees of freedom. In particular we find that if asymmetric inflation is implemented by inflaton decay to color or electroweak charged particles, the oscillation is unobservable. Also if one uses SM singlet fields for this purpose, they must be weakly coupled to the SM fields.

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

García, Abraham; Cotto, María; Duconge, José

The use of hydrogen as replacement for fossil fuels, on which we depend today, is a matter of great relevance. The sustainable generation of hydrogen as fuel is relevant from an environmental and economic point of view. In this study we have explored new synthetic routes for developing new photocatalysts to be used in water splitting, for hydrogen production. Different techniques have been used to produce hydrogen, such as electrolysis, even though these processes have been found to be energetically non suitable. In this research various photocatalytic materials were presented as possible alternatives for using in water splitting processes. Characterizationmore » of the new synthesized materials has been done by using different experimental techniques including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), surface area BET, and X-ray Diffraction (XRD). The efficiency of the synthesized photocatalysts was determined by evaluating the hydrogen evolution by the photocatalytic water splitting reaction.« less

About one counterexample of applying method of splitting in modeling of plating processes

NASA Astrophysics Data System (ADS)

Solovjev, D. S.; Solovjeva, I. A.; Litovka, Yu V.; Korobova, I. L.

2018-05-01

The paper presents the main factors that affect the uniformity of the thickness distribution of plating on the surface of the product. The experimental search for the optimal values of these factors is expensive and time-consuming. The problem of adequate simulation of coating processes is very relevant. The finite-difference approximation using seven-point and five-point templates in combination with the splitting method is considered as solution methods for the equations of the model. To study the correctness of the solution of equations of the mathematical model by these methods, the experiments were conducted on plating with a flat anode and cathode, which relative position was not changed in the bath. The studies have shown that the solution using the splitting method was up to 1.5 times faster, but it did not give adequate results due to the geometric features of the task under the given boundary conditions.

The Multiplicity of the Mitotic Centers and the Time-Course of Their Duplication and Separation

PubMed Central

Mazia, Daniel; Harris, Patricia J.; Bibring, Thomas

1960-01-01

In this study, the reproduction of the mitotic centers in the eggs of a sea urchin, Strongylocentrotus purpuratus and a sand dollar Dendraster excentricus has been studied by means of experimental designs that do not depend on the actual visualization of centrioles. The centers are defined in operational terms as potential poles. Blockage of mitosis by mercaptoethanol, it was found, inhibits the duplication of the centers, but does not inhibit the splitting and separation of centers that have already duplicated and thus potential poles could be realized as actual poles in multipolar divisions. At all times, the center is at least a duplex structure; that is, it contains two potential poles. The actual duplication process is the earliest event in a given mitotic cycle, taking place at very early interphase or in late telophase of the previous division. The splitting of the centers following duplication is a distinct process, dissociable from the duplication as such. Duplication and splitting normally occur at about the same time in the mitotic cycle, with a precession of the former. That is, as the two members of a pair of "old" centers split, each one gives rise to a new one, which remains associated with it until the next phase of splitting and duplication occurs. The results are consistent with what is termed a "generative" model of the self-reproduction of an intracellular body. According to this, the body does not immediately produce a full-fledged copy of itself, with simultaneous fission, but the primary duplication event involves only a part of the parent structure. This gives rise to a "germ" or "seed" which then grows to be equivalent to the parent body, and finally splits from it. PMID:19866563

Data fusion for food authentication. Combining rare earth elements and trace metals to discriminate "Fava Santorinis" from other yellow split peas using chemometric tools.

PubMed

Drivelos, Spiros A; Higgins, Kevin; Kalivas, John H; Haroutounian, Serkos A; Georgiou, Constantinos A

2014-12-15

"Fava Santorinis", is a protected designation of origin (PDO) yellow split pea species growing only in the island of Santorini in Greece. Due to its nutritional quality and taste, it has gained a high monetary value. Thus, it is prone to adulteration with other yellow split peas. In order to discriminate "Fava Santorinis" from other yellow split peas, four classification methods utilising rare earth elements (REEs) measured through inductively coupled plasma-mass spectrometry (ICP-MS) are studied. The four classification processes are orthogonal projection analysis (OPA), Mahalanobis distance (MD), partial least squares discriminant analysis (PLS-DA) and k nearest neighbours (KNN). Since it is known that trace elements are often useful to determine geographical origin of food products, we further quantitated for trace elements using ICP-MS. Presented in this paper are results using the four classification processes based on the fusion of the REEs data with the trace element data. Overall, the OPA method was found to perform best with up to 100% accuracy using the fused data. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Split-Path Schema-Based RFID Data Storage Model in Supply Chain Management

PubMed Central

Fan, Hua; Wu, Quanyuan; Lin, Yisong; Zhang, Jianfeng

2013-01-01

In modern supply chain management systems, Radio Frequency IDentification (RFID) technology has become an indispensable sensor technology and massive RFID data sets are expected to become commonplace. More and more space and time are needed to store and process such huge amounts of RFID data, and there is an increasing realization that the existing approaches cannot satisfy the requirements of RFID data management. In this paper, we present a split-path schema-based RFID data storage model. With a data separation mechanism, the massive RFID data produced in supply chain management systems can be stored and processed more efficiently. Then a tree structure-based path splitting approach is proposed to intelligently and automatically split the movement paths of products. Furthermore, based on the proposed new storage model, we design the relational schema to store the path information and time information of tags, and some typical query templates and SQL statements are defined. Finally, we conduct various experiments to measure the effect and performance of our model and demonstrate that it performs significantly better than the baseline approach in both the data expression and path-oriented RFID data query performance. PMID:23645112

Numerical study on the splitting of a vapor bubble in the ultrasonic assisted EDM process with the curved tool and workpiece.

PubMed

Shervani-Tabar, M T; Seyed-Sadjadi, M H; Shabgard, M R

2013-01-01

Electrical discharge machining (EDM) is a powerful and modern method of machining. In the EDM process, a vapor bubble is generated between the tool and the workpiece in the dielectric liquid due to an electrical discharge. In this process dynamic behavior of the vapor bubble affects machining process. Vibration of the tool surface affects bubble behavior and consequently affects material removal rate (MRR). In this paper, dynamic behavior of the vapor bubble in an ultrasonic assisted EDM process after the appearance of the necking phenomenon is investigated. It is noteworthy that necking phenomenon occurs when the bubble takes the shape of an hour-glass. After the appearance of the necking phenomenon, the vapor bubble splits into two parts and two liquid jets are developed on the boundaries of the upper and lower parts of the vapor bubble. The liquid jet developed on the upper part of the bubble impinges to the tool and the liquid jet developed on the lower part of the bubble impinges to the workpiece. These liquid jets cause evacuation of debris from the gap between the tool and the workpiece and also cause erosion of the workpiece and the tool. Curved tool and workpiece affect the shape and the velocity of the liquid jets during splitting of the vapor bubble. In this paper dynamics of the vapor bubble after its splitting near the curved tool and workpiece is investigated in three cases. In the first case surfaces of the tool and the workpiece are flat, in the second case surfaces of the tool and the workpiece are convex and in the third case surfaces of the tool and workpiece are concave. Numerical results show that in the third case, the velocity of liquid jets which are developed on the boundaries of the upper and lower parts of the vapor bubble after its splitting have the highest magnitude and their shape are broader than the other cases. Copyright © 2012 Elsevier B.V. All rights reserved.

One‐dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting

PubMed Central

Ge, Mingzheng; Li, Qingsong; Cao, Chunyan; Huang, Jianying; Li, Shuhui; Zhang, Songnan; Chen, Zhong; Zhang, Keqin; Al‐Deyab, Salem S.

2016-01-01

Hydrogen production from water splitting by photo/photoelectron‐catalytic process is a promising route to solve both fossil fuel depletion and environmental pollution at the same time. Titanium dioxide (TiO2) nanotubes have attracted much interest due to their large specific surface area and highly ordered structure, which has led to promising potential applications in photocatalytic degradation, photoreduction of CO2, water splitting, supercapacitors, dye‐sensitized solar cells, lithium‐ion batteries and biomedical devices. Nanotubes can be fabricated via facile hydrothermal method, solvothermal method, template technique and electrochemical anodic oxidation. In this report, we provide a comprehensive review on recent progress of the synthesis and modification of TiO2 nanotubes to be used for photo/photoelectro‐catalytic water splitting. The future development of TiO2 nanotubes is also discussed. PMID:28105391

Strain Measurements within Fibreboard. Part III: Analyzing the Process Zone at the Crack Tip of Medium Density Fiberboards (MDF) Double Cantilever I-Beam Specimens

PubMed Central

Rathke, Jörn; Müller, Ulrich; Konnerth, Johannes; Sinn, Gerhard

2012-01-01

This paper is the third part of a study dealing with the mechanical and fracture mechanical characterization of Medium Density Fiberboards (MDF). In the first part, an analysis of internal bond strength testing was performed and in the second part MDF was analyzed by means of the wedge splitting experiment; this part deals with the double cantilever I beam test, which is designed for measuring the fracture energy as well as stress intensity factor in Mode I. For a comparison of isotropic and orthotropic material behavior, finite element modeling was performed. In addition to the calculation of fracture energy the stress intensity factor was analyzed by means of finite elements simulation and calculation. In order to analyze strain deformations and the process zone, electronic speckle pattern interferometry measurements were performed. The results revealed an elongated process zone and lower results for KIC if compared to the wedge splitting experiment. The Gf numbers are higher compared to the wedge splitting results and can be explained by the thicker process zone formed during the crack propagation. The process zone width on its part is influenced by the stiff reinforcements and yields a similar crack surface as with the internal bond test.

Bound states, scattering states, and resonant states in PT -symmetric open quantum systems

NASA Astrophysics Data System (ADS)

Garmon, Savannah; Gianfreda, Mariagiovanna; Hatano, Naomichi

2015-08-01

We study a simple open quantum system with a PT -symmetric defect potential as a prototype in order to illustrate a number of general features of PT -symmetric open quantum systems; however, the potential itself could be mimicked by a number of PT systems that have been experimentally studied quite recently. One key feature is the resonance in continuum (RIC), which appears in both the discrete spectrum and the scattering spectrum of such systems. The RIC wave function forms a standing wave extending throughout the spatial extent of the system and in this sense represents a resonance between the open environment associated with the leads of our model and the central PT -symmetric potential. We also illustrate that as one deforms the system parameters, the RIC may exit the continuum by splitting into a bound state and a virtual bound state at the band edge, a process which should be experimentally observable. We also study the exceptional points appearing in the discrete spectrum at which two eigenvalues coalesce; we categorize these as either EP2As, at which two real-valued solutions coalesce before becoming complex-valued, and EP2Bs, for which the two solutions are complex on either side of the exceptional point. The EP2As are associated with PT -symmetry breaking; we argue that these are more stable against parameter perturbation than the EP2Bs. We also study complex-valued solutions of the discrete spectrum for which the wave function is nevertheless spatially localized, something that is not allowed in traditional open quantum systems; we illustrate that these may form quasibound states in continuum under some circumstances. We also study the scattering properties of the system, including states that support invisible propagation and some general features of perfect transmission states. We finally use our model as a prototype for the construction of scattering states that satisfy PT -symmetric boundary conditions; while these states do not conserve the traditional probability current, we introduce the PT current which is preserved. The perfect transmission states appear as a special case of the PT -symmetric scattering states.

CMOS-compatible 2-bit optical spectral quantization scheme using a silicon-nanocrystal-based horizontal slot waveguide

PubMed Central

Kang, Zhe; Yuan, Jinhui; Zhang, Xianting; Wu, Qiang; Sang, Xinzhu; Farrell, Gerald; Yu, Chongxiu; Li, Feng; Tam, Hwa Yaw; Wai, P. K. A.

2014-01-01

All-optical analog-to-digital converters based on the third-order nonlinear effects in silicon waveguide are a promising candidate to overcome the limitation of electronic devices and are suitable for photonic integration. In this paper, a 2-bit optical spectral quantization scheme for on-chip all-optical analog-to-digital conversion is proposed. The proposed scheme is realized by filtering the broadened and split spectrum induced by the self-phase modulation effect in a silicon horizontal slot waveguide filled with silicon-nanocrystal. Nonlinear coefficient as high as 8708 W−1/m is obtained because of the tight mode confinement of the horizontal slot waveguide and the high nonlinear refractive index of the silicon-nanocrystal, which provides the enhanced nonlinear interaction and accordingly low power threshold. The results show that a required input peak power level less than 0.4 W can be achieved, along with the 1.98-bit effective-number-of-bit and Gray code output. The proposed scheme can find important applications in on-chip all-optical digital signal processing systems. PMID:25417847

CMOS-compatible 2-bit optical spectral quantization scheme using a silicon-nanocrystal-based horizontal slot waveguide.

PubMed

Kang, Zhe; Yuan, Jinhui; Zhang, Xianting; Wu, Qiang; Sang, Xinzhu; Farrell, Gerald; Yu, Chongxiu; Li, Feng; Tam, Hwa Yaw; Wai, P K A

2014-11-24

All-optical analog-to-digital converters based on the third-order nonlinear effects in silicon waveguide are a promising candidate to overcome the limitation of electronic devices and are suitable for photonic integration. In this paper, a 2-bit optical spectral quantization scheme for on-chip all-optical analog-to-digital conversion is proposed. The proposed scheme is realized by filtering the broadened and split spectrum induced by the self-phase modulation effect in a silicon horizontal slot waveguide filled with silicon-nanocrystal. Nonlinear coefficient as high as 8708 W(-1)/m is obtained because of the tight mode confinement of the horizontal slot waveguide and the high nonlinear refractive index of the silicon-nanocrystal, which provides the enhanced nonlinear interaction and accordingly low power threshold. The results show that a required input peak power level less than 0.4 W can be achieved, along with the 1.98-bit effective-number-of-bit and Gray code output. The proposed scheme can find important applications in on-chip all-optical digital signal processing systems.

POLARIZED SCATTERING OF LIGHT FOR ARBITRARY MAGNETIC FIELDS WITH LEVEL-CROSSINGS FROM THE COMBINATION OF HYPERFINE AND FINE STRUCTURE SPLITTINGS

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

Sowmya, K.; Nagendra, K. N.; Sampoorna, M.

2015-12-01

Interference between magnetic substates of the hyperfine structure states belonging to different fine structure states of the same term influences the polarization for some of the diagnostically important lines of the Sun's spectrum, like the sodium and lithium doublets. The polarization signatures of this combined interference contain information on the properties of the solar magnetic fields. Motivated by this, in the present paper, we study the problem of polarized scattering on a two-term atom with hyperfine structure by accounting for the partial redistribution in the photon frequencies arising due to the Doppler motions of the atoms. We consider the scatteringmore » atoms to be under the influence of a magnetic field of arbitrary strength and develop a formalism based on the Kramers–Heisenberg approach to calculate the scattering cross section for this process. We explore the rich polarization effects that arise from various level-crossings in the Paschen–Back regime in a single scattering case using the lithium atomic system as a concrete example that is relevant to the Sun.« less

Easy synthesis of bismuth iron oxide nanoparticles as photocatalyst for solar hydrogen generation from water

NASA Astrophysics Data System (ADS)

Deng, Jinyi

In this study, high purity bismuth iron oxide (BiFeO3/BFO) nanoparticles of size 50-80 nm have been successfully synthesized by a simple sol-gel method using urea and polyvinyl alcohol at low temperature. X-ray diffraction (XRD) measurement is used to optimize the synthetic process to get highly crystalline and pure phase material. Diffuse reflectance ultraviolet-visible (DRUV-Vis) spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about 620 nm, corresponding to an energy band gap of 2.1 eV. Compared to BaTiO3, BFO has a better degradation of methyl orange under light radiation. Also, photocatalytic tests prove this material to be efficient towards water splitting under simulated solar light to generate hydrogen. The simple synthetic methodology adopted in this paper will be useful in developing low-cost semiconductor materials as effective photocatalysts for hydrogen generation. Photocatalytic tests followed by gas chromatography (GC) analyses show that BiFeO3 generates three times more hydrogen than commercial titania P25 catalyst under the same experimental conditions.

Development of a collinear laser spectrometer facility at VECC: First test result

NASA Astrophysics Data System (ADS)

Ali, Md Sabir; Ray, Ayan; Raja, Waseem; Bandyopadhyay, Arup; Naik, Vaishali; Polley, Asish; Chakrabarti, Alok

2018-04-01

We report here the development of collinear laser spectroscopy (CLS) system at VECC for the study of hyperfine spectrum and isotopic shift of stable and unstable isotopes. The facility is first of its kind in the country allowing measurement of hyperfine splitting of atomic levels using atomic beams. The CLS system is installed downstream of the focal plane of the existing isotope separator online (ISOL) facility at VECC and is recently commissioned by successfully resolving the fluorescence spectrum of the hyperfine levels in ^{85,87}Rb. The atomic beams of Rb were produced by charge exchange of 8 keV Rb ion beam which were produced, extracted and transported to the charge exchange cell using the ion sources, extractor and the beam-line magnets of the ISOL facility. The laser propagating opposite to the ion / atom beam direction was allowed to interact with the atom beam and fluorescence spectrum was recorded. The experimental set-up and the experiment conducted are reported in detail. The measures needed to be carried out for improving the sensitivity to a level necessary for studying short-lived exotic nuclei have also been discussed.

Hybrid solar collector using nonimaging optics and photovoltaic components

NASA Astrophysics Data System (ADS)

Winston, Roland; Yablonovitch, Eli; Jiang, Lun; Widyolar, Bennett K.; Abdelhamid, Mahmoud; Scranton, Gregg; Cygan, David; Kozlov, Alexandr

2015-08-01

The project team of University of California at Merced (UC-M), Gas Technology Institute, and Dr. Eli Yablonovitch of University of California at Berkeley developed a novel hybrid concentrated solar photovoltaic thermal (PV/T) collector using nonimaging optics and world record single-junction Gallium arsenide (GaAs) PV components integrated with particle laden gas as thermal transfer and storage media, to simultaneously generate electricity and high temperature dispatchable heat. The collector transforms a parabolic trough, commonly used in CSP plants, into an integrated spectrum-splitting device. This places a spectrum-sensitive topping element on a secondary reflector that is registered to the thermal collection loop. The secondary reflector transmits higher energy photons for PV topping while diverting the remaining lower energy photons to the thermal media, achieving temperatures of around 400°C even under partial utilization of the solar spectrum. The collector uses the spectral selectivity property of Gallium arsenide (GaAs) cells to maximize the exergy output of the system, resulting in an estimated exergy efficiency of 48%. The thermal media is composed of fine particles of high melting point material in an inert gas that increases heat transfer and effectively stores excess heat in hot particles for later on-demand use.

Particle-hole symmetry, many-body localization, and topological edge modes

NASA Astrophysics Data System (ADS)

Vasseur, Romain; Friedman, Aaron J.; Parameswaran, S. A.; Potter, Andrew C.

We study the excited states of interacting fermions in one dimension with particle-hole symmetric disorder (equivalently, random-bond XXZ chains) using a combination of renormalization group methods and exact diagonalization. Absent interactions, the entire many-body spectrum exhibits infinite-randomness quantum critical behavior with highly degenerate excited states. We show that though interactions are an irrelevant perturbation in the ground state, they drastically affect the structure of excited states: even arbitrarily weak interactions split the degeneracies in favor of thermalization (weak disorder) or spontaneously broken particle-hole symmetry, driving the system into a many-body localized spin glass phase (strong disorder). In both cases, the quantum critical properties of the non-interacting model are destroyed, either by thermal decoherence or spontaneous symmetry breaking. This system then has the interesting and counterintuitive property that edges of the many-body spectrum are less localized than the center of the spectrum. We argue that our results rule out the existence of certain excited state symmetry-protected topological orders. Supported by the Gordon and Betty Moore Foundation's EPiQS Initiative (Grant GBMF4307 (ACP), the Quantum Materials Program at LBNL (RV), NSF Grant DMR-1455366 and UCOP Research Catalyst Award No. CA-15-327861 (SAP).

Spectrum and energy levels of kryptonlike ion Nb VI

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

Reader, J.; Ekberg, J.O.

1993-05-01

The spectrum of five-times ionized niobium, Nb, VI, was observed from 238 to 2700 {angstrom} with sliding spark discharges on 10.7-m normal- and grazing-incidence spectrographs. Experimental energies were determined for all levels of the 4s{sup 2}4p{sup 6}, 4s{sup 2}4p{sup 6}, 4s{sup 2}4p{sup 5}4d, 4f, 5s, 5p, 5g, 6s, and 4s4p{sup 6}4d configurations as well as some levels of 4p{sup 5}6g. A total of 291 lines were classified as transitions between 88 observed levels. A previous analysis of this spectrum was found to be totally erroneous. Large hyperfine splittings were found for several levels of the 4p{sup 5}5s and 5p configurations.more » The observed configurations were theoretically interpreted by means of Hartree-Fock calculations and least squares fits of the energy parameters to the observed levels. A revised value of the ionization energy was obtained from the 4p{sup 5}5g and 6g configurations.« less

Simultaneous topography imaging and broadband nanomechanical mapping on atomic force microscope

NASA Astrophysics Data System (ADS)

Li, Tianwei; Zou, Qingze

2017-12-01

In this paper, an approach is proposed to achieve simultaneous imaging and broadband nanomechanical mapping of soft materials in air by using an atomic force microscope. Simultaneous imaging and nanomechanical mapping are needed, for example, to correlate the morphological and mechanical evolutions of the sample during dynamic phenomena such as the cell endocytosis process. Current techniques for nanomechanical mapping, however, are only capable of capturing static elasticity of the material, or the material viscoelasticity in a narrow frequency band around the resonant frequency(ies) of the cantilever used, not competent for broadband nanomechanical mapping, nor acquiring topography image of the sample simultaneously. These limitations are addressed in this work by enabling the augmentation of an excitation force stimuli of rich frequency spectrum for nanomechanical mapping in the imaging process. Kalman-filtering technique is exploited to decouple and split the mixed signals for imaging and mapping, respectively. Then the sample indentation generated is quantified online via a system-inversion method, and the effects of the indentation generated and the topography tracking error on the topography quantification are taken into account. Moreover, a data-driven feedforward-feedback control is utilized to track the sample topography. The proposed approach is illustrated through experimental implementation on a polydimethylsiloxane sample with a pre-fabricated pattern.

Determination of rheological parameters of liquid crystals with zero anisotropy of diamagnetic susceptibility

NASA Astrophysics Data System (ADS)

Korotey, E. V.; Sinyavskii, N. Ya.

2007-07-01

A new method for determination of rheological parameters of liquid crystals with zero anisotropy of diamagnetic susceptibility is proposed, which is based on the measurement of the quadrupole splitting line of the NMR 2H spectrum. The method provides higher information content of the experiments, with the shear flow discarded from consideration, compared to that obtained by the classical Leslie-Ericksen theory. A comparison with the experiment is performed, the coefficients of anisotropic viscosity of lecithin/D2O/cyclohexane are determined, and a conclusion is drawn as concerns the domain shapes.

Design and analysis of all-dielectric broadband nonpolarizing parallel-plate beam splitters.

PubMed

Wang, Wenliang; Xiong, Shengming; Zhang, Yundong

2007-06-01

Past research on the all-dielectric nonpolarizing beam splitter is reviewed. With the aid of the needle thin-film synthesis method and the conjugate graduate refine method, three different split ratio nonpolarizing parallel-plate beam splitters over a 200 nm spectral range centered at 550 nm with incidence angles of 45 degrees are designed. The chosen materials component and the initial stack are based on the Costich and Thelen theories. The results of design and analysis show that the designs maintain a very low polarization ratio in the working range of the spectrum and has a reasonable angular field.

All-dielectric broadband non-polarizing parallel plate beam splitter operating between 450-650nm

NASA Astrophysics Data System (ADS)

Wang, Wenliang; Xiong, Shenming; Zhang, Yundong

2007-12-01

Past research on all-dielectric non-polarizing beam splitter is reviewed. With the aid of needle thin film synthesis method and conjugate graduate refining method, three non-polarizing parallel plate beam splitters with different split ratios over a 200nm spectral range centered at 550nm with incidence angle 45° are designed. Selection of material components and initial stack are based on Costich and Thelen's theory. The results of design and analysis show that it maintains a very low polarization ratio in the working range of spectrum and has a reasonable angular field.

The clustering of primordial black holes

NASA Astrophysics Data System (ADS)

Chisholm, James R.

2005-12-01

We investigate the spatial clustering properties of primordial black holes (PBHs). With minimal assumptions, we show that PBHs are created highly clustered. They constitute an isocurvature perturbation that is non-linear upon horizon entry. Using the peak-background split model of bias, we compute the PBH two-point correlation function and power spectrum. A consequence of this is that PBHs cannot serve as the majority of dark matter in the universe. We show that this clustering leads to PBH mergers which spoil the mass-creation time relation. We examine the prospect of PBHs being the seeds of Supermassive Black Holes as well.

Structural transition in lanthanum gallate and transformation of the fine structure of the EPR spectrum of a Gd3+ impurity center

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Guseva, V. B.; Fokin, A. V.; Potapov, A. P.; Artyomov, M. Yu.

2011-04-01

Abrupt changes in resonance positions, hysteretic temperature behavior, and coexistence of phases, which indicate a first-order phase transition, have been revealed from measurements of temperature dependences of the EPR spectra of Gd3+ and Mn4+ centers in the vicinity of the structural transition of lanthanum gallate. The transformation of monoclinic Gd3+ centers into trigonal Gd3+ centers upon the phase transition has been used to estimate the adequacy of two approximations of the superposition model for parameters of the zero-field splitting of the ground state.

Coulomb versus spin-orbit interaction in few-electron carbon-nanotube quantum dots

NASA Astrophysics Data System (ADS)

Secchi, Andrea; Rontani, Massimo

2009-07-01

Few-electron states in carbon-nanotube quantum dots are studied by means of the configuration-interaction method. The peculiar noninteracting feature of the tunneling spectrum for two electrons, recently measured by F. Kuemmeth, S. Ilani, D. C. Ralph, and P. L. McEuen [Nature (London) 452, 448 (2008)], is explained by the splitting of a low-lying isospin multiplet due to spin-orbit interaction. Nevertheless, the strongly interacting ground state forms a “Wigner molecule” made of electrons localized in space. Signatures of the electron molecule may be seen in tunneling spectra by varying the tunable dot confinement potential.

One-Shot Determination of Residual Dipolar Couplings: Application to the Structural Discrimination of Small Molecules Containing Multiple Stereocenters.

PubMed

Castañar, Laura; Garcia, Manuela; Hellemann, Erich; Nolis, Pau; Gil, Roberto R; Parella, Teodor

2016-11-18

A novel approach for the fast and efficient structural discrimination of molecules containing multiple stereochemical centers is described. A robust J-resolved HSQC experiment affording highly resolved 1 J CH / 1 T CH splittings along the indirect dimension and homodecoupled 1 H signals in the detected dimension is proposed. The experiment enables in situ distinction of both isotropic and anisotropic components of molecules dissolved in compressed PMMA gels, allowing a rapid and direct one-shot determination of accurate residual dipolar coupling constants from a single NMR spectrum.

Kinetic and spectroscopic characterization of tungsten-substituted DMSO reductase from Rhodobacter sphaeroides.

PubMed

Pacheco, Josué; Niks, Dimitri; Hille, Russ

2018-03-01

We have examined the kinetic and spectroscopic properties of a tungsten-substituted form of DMSO reductase from Rhodobacter sphaeroides, an enzyme that normally possesses molybdenum. Partial reduction with sodium dithionite yields a well-resolved W(V) EPR signal of the so-called "high-g split" type that exhibits markedly greater g-anisotropy than the corresponding Mo(V) signal of the native form of the enzyme, with the g values shifted to higher magnetic field by as much as Δg ave  = 0.056. Deuteration of the enzyme confirms that the coupled proton is solvent-exchangeable, allowing us to accurately simulate the tungsten hyperfine coupling. Global curve-fitting analysis of UV/vis absorption spectra observed in the course of the reaction of the tungsten-substituted enzyme with sodium dithionite affords a well-defined absorption spectrum for the W(V) species. Surprisingly, the absorption spectrum for this species exhibits significantly larger molar extinction coefficients than either the reduced or the oxidized spectrum. This spectrum, in conjunction with those for fully oxidized W(VI) and fully reduced W(IV) enzyme, has been used to deconvolute the absorption spectra seen in the course of turnover, in the which enzyme is reacted with sodium dithionite and DMSO, demonstrating that the W(V) is an authentic catalytic intermediate that accumulates to approximately 50% of the total enzyme in the steady state.

Role of the d -d interaction in the antiferromagnetic phase of λ -(BEDT-STF ) 2FeCl4

NASA Astrophysics Data System (ADS)

Minamidate, Takaaki; Shindo, Hironori; Ihara, Yoshihiko; Kawamoto, Atsushi; Matsunaga, Noriaki; Nomura, Kazushige

2018-03-01

Magnetic susceptibility and proton nuclear magnetic resonance (1H-NMR ) measurements were performed for the quasi-two-dimensional π -d interacting system λ -(BEDT-STF ) 2FeCl4 at ambient pressure. Magnetic susceptibility arising from the 3 d spins of the FeCl4 anion show an anisotropy at low temperature and its temperature dependence for the external field parallel to the c axis is described as a broad peak structure at 8 K. A sharp peak in the temperature dependence of T1-1 associated with the antiferromagnetic (AF) transition is observed at TAF=16 K, together with the drastic splitting of the NMR spectrum below TAF. The relation between the static susceptibility and the splitting of the NMR shift suggests the existence of the relatively strong d -d AF interaction. These results can be explained by the model considering the AF-coupled d -spin system in the AF long-range-ordered π -spin system. We find that the AF phases in λ -type salts can be universally explained by this model.

Efficient single-pixel multispectral imaging via non-mechanical spatio-spectral modulation.

PubMed

Li, Ziwei; Suo, Jinli; Hu, Xuemei; Deng, Chao; Fan, Jingtao; Dai, Qionghai

2017-01-27

Combining spectral imaging with compressive sensing (CS) enables efficient data acquisition by fully utilizing the intrinsic redundancies in natural images. Current compressive multispectral imagers, which are mostly based on array sensors (e.g, CCD or CMOS), suffer from limited spectral range and relatively low photon efficiency. To address these issues, this paper reports a multispectral imaging scheme with a single-pixel detector. Inspired by the spatial resolution redundancy of current spatial light modulators (SLMs) relative to the target reconstruction, we design an all-optical spectral splitting device to spatially split the light emitted from the object into several counterparts with different spectrums. Separated spectral channels are spatially modulated simultaneously with individual codes by an SLM. This no-moving-part modulation ensures a stable and fast system, and the spatial multiplexing ensures an efficient acquisition. A proof-of-concept setup is built and validated for 8-channel multispectral imaging within 420~720 nm wavelength range on both macro and micro objects, showing a potential for efficient multispectral imager in macroscopic and biomedical applications.

Split Dirac cones in HgTe/CdTe quantum wells due to symmetry-enforced level anticrossing at interfaces

NASA Astrophysics Data System (ADS)

Tarasenko, S. A.; Durnev, M. V.; Nestoklon, M. O.; Ivchenko, E. L.; Luo, Jun-Wei; Zunger, Alex

2015-02-01

HgTe is a band-inverted compound which forms a two-dimensional topological insulator if sandwiched between CdTe barriers for a HgTe layer thickness above the critical value. We describe the fine structure of Dirac states in the HgTe/CdTe quantum wells of critical and close-to-critical thicknesses and show that the necessary creation of interfaces brings in another important physical effect: the opening of a significant anticrossing gap between the tips of the Dirac cones. The level repulsion driven by the natural interface inversion asymmetry of zinc-blende heterostructures considerably modifies the electron states and dispersion but preserves the topological transition at the critical thickness. By combining symmetry analysis, atomistic calculations, and extended k .p theory with interface terms, we obtain a quantitative description of the energy spectrum and extract the interface mixing coefficient. We discuss how the fingerprints of the predicted zero-magnetic-field splitting of the Dirac cones could be detected experimentally by studying magnetotransport phenomena, cyclotron resonance, Raman scattering, and THz radiation absorption.

Automatic detection of cone photoreceptors in split detector adaptive optics scanning light ophthalmoscope images.

PubMed

Cunefare, David; Cooper, Robert F; Higgins, Brian; Katz, David F; Dubra, Alfredo; Carroll, Joseph; Farsiu, Sina

2016-05-01

Quantitative analysis of the cone photoreceptor mosaic in the living retina is potentially useful for early diagnosis and prognosis of many ocular diseases. Non-confocal split detector based adaptive optics scanning light ophthalmoscope (AOSLO) imaging reveals the cone photoreceptor inner segment mosaics often not visualized on confocal AOSLO imaging. Despite recent advances in automated cone segmentation algorithms for confocal AOSLO imagery, quantitative analysis of split detector AOSLO images is currently a time-consuming manual process. In this paper, we present the fully automatic adaptive filtering and local detection (AFLD) method for detecting cones in split detector AOSLO images. We validated our algorithm on 80 images from 10 subjects, showing an overall mean Dice's coefficient of 0.95 (standard deviation 0.03), when comparing our AFLD algorithm to an expert grader. This is comparable to the inter-observer Dice's coefficient of 0.94 (standard deviation 0.04). To the best of our knowledge, this is the first validated, fully-automated segmentation method which has been applied to split detector AOSLO images.

Plasmon inducing effects for enhanced photoelectrochemical water splitting: X-ray absorption approach to electronic structures.

PubMed

Chen, Hao Ming; Chen, Chih Kai; Chen, Chih-Jung; Cheng, Liang-Chien; Wu, Pin Chieh; Cheng, Bo Han; Ho, You Zhe; Tseng, Ming Lun; Hsu, Ying-Ya; Chan, Ting-Shan; Lee, Jyh-Fu; Liu, Ru-Shi; Tsai, Din Ping

2012-08-28

Artificial photosynthesis using semiconductors has been investigated for more than three decades for the purpose of transferring solar energy into chemical fuels. Numerous studies have revealed that the introduction of plasmonic materials into photochemical reaction can substantially enhance the photo response to the solar splitting of water. Until recently, few systematic studies have provided clear evidence concerning how plasmon excitation and which factor dominates the solar splitting of water in photovoltaic devices. This work demonstrates the effects of plasmons upon an Au nanostructure-ZnO nanorods array as a photoanode. Several strategies have been successfully adopted to reveal the mutually independent contributions of various plasmonic effects under solar irradiation. These have clarified that the coupling of hot electrons that are formed by plasmons and the electromagnetic field can effectively increase the probability of a photochemical reaction in the splitting of water. These findings support a new approach to investigating localized plasmon-induced effects and charge separation in photoelectrochemical processes, and solar water splitting was used herein as platform to explore mechanisms of enhancement of surface plasmon resonance.

The development of flux-split algorithms for flows with non-equilibrium thermodynamics and chemical reactions

NASA Technical Reports Server (NTRS)

Grossman, B.; Cinella, P.

1988-01-01

A finite-volume method for the numerical computation of flows with nonequilibrium thermodynamics and chemistry is presented. A thermodynamic model is described which simplifies the coupling between the chemistry and thermodynamics and also results in the retention of the homogeneity property of the Euler equations (including all the species continuity and vibrational energy conservation equations). Flux-splitting procedures are developed for the fully coupled equations involving fluid dynamics, chemical production and thermodynamic relaxation processes. New forms of flux-vector split and flux-difference split algorithms are embodied in a fully coupled, implicit, large-block structure, including all the species conservation and energy production equations. Several numerical examples are presented, including high-temperature shock tube and nozzle flows. The methodology is compared to other existing techniques, including spectral and central-differenced procedures, and favorable comparisons are shown regarding accuracy, shock-capturing and convergence rates.

Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics

NASA Technical Reports Server (NTRS)

Xu, Kun

1998-01-01

A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.

Effects of inorganic substances on water splitting in ion-exchange membranes; II. Optimal contents of inorganic substances in preparing bipolar membranes.

PubMed

Kang, Moon-Sung; Choi, Yong-Jin; Moon, Seung-Hyeon

2004-05-15

An approach to enhancing the water-splitting performance of bipolar membranes (BPMs) is introducing an inorganic substance at the bipolar (BP) junction. In this study, the immobilization of inorganic matters (i.e., iron hydroxides and silicon compounds) at the BP junction and the optimum concentration have been investigated. To immobilize these inorganic matters, novel methods (i.e., electrodeposition of the iron hydroxide and processing of the sol-gel to introduce silicon groups at the BP junction) were suggested. At optimal concentrations, the immobilized inorganic matters significantly enhanced the water-splitting fluxes, indicating that they provide alternative paths for water dissociation, but on the other hand possibly reduce the polarization of water molecules between the sulfonic acid and quaternary ammonium groups at high contents. Consequently, the amount of inorganic substances introduced should be optimized to obtain the maximum water splitting in the BPM.

Zeeman Splitting of Ferromagnetic GaMnAs on InP Observed by Magnetic Circular Dichroism in Reflection Mode

NASA Astrophysics Data System (ADS)

Tanaka, H.; Bsatee, M.; Jadwisienczak, W. M.

2016-08-01

Systematic investigations of Ga1- x Mn x As grown on InP with different Mn concentrations have been conducted using magnetic circular dichroism (MCD) in reflection mode. The MCD spectrum of Ga0.97Mn0.03As/InP was decomposed into two dispersion curves originating from E 1 and E 1 + Δ1 optical transitions using the energy derivative of a Gaussian function. The Zeeman splitting energy E 1 at the L critical point (0.6 meV) of ferromagnetic Ga0.97Mn0.03As/InP was estimated using a rigid band shift model. Based on the relationship between E 1 and E 0 (Γ critical point) observed in Cd1- x Mn x Te dilute magnetic semiconductor (DMS), the Zeeman splitting energy E 1 (9.6 meV) of ferromagnetic Ga1- x Mn x As/InP was calculated. In addition, it was established that the peaks in the MCD spectra at L critical points shift toward the lower energy side as the Mn concentration is increased, and the observed shift saturates for Mn content of x = 0.001. Furthermore, the measured absorption spectra for Ga1- x Mn x As/InP did not show noticeable peak shifts with increasing Mn content. This suggests that the s, p- d exchange interaction induced in Ga1- x Mn x As/InP has localized nature due to the presence of a Mn rigid sphere of influence.

Progress Towards a New Technique for Measuring Local Electric and Magnetic Field Fluctuations in High Temperature Plasmas

NASA Astrophysics Data System (ADS)

Burke, M. G.; Fonck, R. J.; McKee, G. R.; Winz, G. R.

2017-10-01

Local measurements of electrostatic and magnetic turbulence in fusion grade plasmas is a critical missing component in advancing our understanding of current experiments and validating nonlinear turbulence simulations. A novel diagnostic for measuring local electric and magnetic field fluctuations (Ẽ and B ) is being developed to address this need. It employs high-speed measurements of the spectral linewidth and/or line intensities of the Motional Stark Effect split neutral beam emission. This emission is split into several spectral components, with the amount of splitting being proportional to local magnetic and electric fields at the emission site. High spectral resolution ( 0.025 nm), high throughput ( 0.01 cm2str), and high speed (f 250 kHz) are required for the measurement of fast changes in the MSE spectrum. Spatial heterodyne spectroscopy (SHS) techniques coupled to a CMOS detector can meet these demands. A prototype SHS has been deployed to DIII-D for initial testing in the tokamak environment, SNR evaluation, and neutral beam efficacy. In addition, design studies of the SHS interferogram are ongoing to further optimize the measurement technique. One major contributor to loss of fringe contrast is line broadening arising from employing a large collection lens. This broadening can be mitigated by making the lens at the tokamak wall optically conjugate with the interference fringes image field. Work supported by US DOE Grant DE-FG02-89ER53296.

Tablet splitting: is it worthwhile? Analysis of drug content and weight uniformity for half tablets of 16 commonly used medications in the outpatient setting.

PubMed

Helmy, Sally A

2015-01-01

Tablet splitting is a well-established medical practice in clinical settings for multiple reasons, including cost savings and ease of swallowing. However, it does not necessarily result in weight-uniform half tablets. To (a) investigate the effect of tablet characteristics on weight and content uniformity of half tablets, resulting from splitting 16 commonly used medications in the outpatient setting and (b) provide recommendations for safe tablet-splitting prescribing practices. Ten random tablets from each of the selected medications were weighed and split by 5 volunteers (2 men and 3 women aged 25-44 years) using a knife. The selected medications were mirtazapine 30 mg, bromazepam 3 mg, oxcarbazepin 150 mg, sertraline 50 mg, carvedilol 25 mg, bisoprolol fumarate 10 mg, losartan 50 mg, digoxin 0.25 mg, amiodarone HCl 200 mg, metformin HCl 1,000 mg, glimepiride 4 mg, montelukast 10 mg, ibuprofen 600 mg, celecoxib 200 mg, meloxicam 15 mg, and sildenafil citrate 50 mg. The resulting half tablets were evaluated for weight and drug content uniformity in accordance with proxy United States Pharmacopeia (USP) specification (95%-105% for digoxin and 90%-110% for the other 15 drugs). Weight and drug content uniformity were assessed by comparing weight or drug content of the half tablets with one-half of the mean weight or drug content for all whole tablets in the sample. The percentages by which the weight and drug content of each whole tablet or half tablet differed from sample mean values were calculated. Other relevant physical characteristics of the 16 products were measured. A total of 52 of 320 half tablets (16.2%) and 48 of 320 half tablets (15.0%) fell outside of the proxy USP specification for weight and drug content, respectively. Bromazepam, carvedilol, bisoprolol, losartan, digoxin, and meloxicam half tablets failed the weight and content uniformity test; however, the half tablets for the rest of the medications passed the test. Mean percent weight loss after splitting was less than 1.5% for all drugs. Bromazepam, carvedilol, and digoxin showed the highest powdering loss during the tablet-splitting process. Tablet splitting could be safer and easier when drug- and patient-specific criteria have been met. Tablet size, shape, and hardness may also play a role in the decision to split a tablet or not. Tablets containing drugs with a wide therapeutic index and long half-life might be more suitable candidates for division. Dose variation exceeded a proxy USP specification for more than one-third of sampled half tablets of bromazepam, carvedilol, bisoprolol, and digoxin. Drug content variation in half tablets appeared to be attributed to weight variation due to fragment or powder loss during the splitting process.

49 CFR 40.153 - How does the MRO notify employees of their right to a test of the split specimen?

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 1 2013-10-01 2013-10-01 false How does the MRO notify employees of their right to a test of the split specimen? 40.153 Section 40.153 Transportation Office of the Secretary of Transportation PROCEDURES FOR TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Medical Review Officers and the Verification Process § 40.153 Ho...

A hybrid flowshop scheduling model considering dedicated machines and lot-splitting for the solar cell industry

NASA Astrophysics Data System (ADS)

Wang, Li-Chih; Chen, Yin-Yann; Chen, Tzu-Li; Cheng, Chen-Yang; Chang, Chin-Wei

2014-10-01

This paper studies a solar cell industry scheduling problem, which is similar to traditional hybrid flowshop scheduling (HFS). In a typical HFS problem, the allocation of machine resources for each order should be scheduled in advance. However, the challenge in solar cell manufacturing is the number of machines that can be adjusted dynamically to complete the job. An optimal production scheduling model is developed to explore these issues, considering the practical characteristics, such as hybrid flowshop, parallel machine system, dedicated machines, sequence independent job setup times and sequence dependent job setup times. The objective of this model is to minimise the makespan and to decide the processing sequence of the orders/lots in each stage, lot-splitting decisions for the orders and the number of machines used to satisfy the demands in each stage. From the experimental results, lot-splitting has significant effect on shortening the makespan, and the improvement effect is influenced by the processing time and the setup time of orders. Therefore, the threshold point to improve the makespan can be identified. In addition, the model also indicates that more lot-splitting approaches, that is, the flexibility of allocating orders/lots to machines is larger, will result in a better scheduling performance.

Multi-response optimization of Artemia hatching process using split-split-plot design based response surface methodology

PubMed Central

Arun, V. V.; Saharan, Neelam; Ramasubramanian, V.; Babitha Rani, A. M.; Salin, K. R.; Sontakke, Ravindra; Haridas, Harsha; Pazhayamadom, Deepak George

2017-01-01

A novel method, BBD-SSPD is proposed by the combination of Box-Behnken Design (BBD) and Split-Split Plot Design (SSPD) which would ensure minimum number of experimental runs, leading to economical utilization in multi- factorial experiments. The brine shrimp Artemia was tested to study the combined effects of photoperiod, temperature and salinity, each with three levels, on the hatching percentage and hatching time of their cysts. The BBD was employed to select 13 treatment combinations out of the 27 possible combinations that were grouped in an SSPD arrangement. Multiple responses were optimized simultaneously using Derringer’s desirability function. Photoperiod and temperature as well as temperature-salinity interaction were found to significantly affect the hatching percentage of Artemia, while the hatching time was significantly influenced by photoperiod and temperature, and their interaction. The optimum conditions were 23 h photoperiod, 29 °C temperature and 28 ppt salinity resulting in 96.8% hatching in 18.94 h. In order to verify the results obtained from BBD-SSPD experiment, the experiment was repeated preserving the same set up. Results of verification experiment were found to be similar to experiment originally conducted. It is expected that this method would be suitable to optimize the hatching process of animal eggs. PMID:28091611

Methods and circuitry for reconfigurable SEU/SET tolerance

NASA Technical Reports Server (NTRS)

Shuler, Jr., Robert L. (Inventor)

2010-01-01

A device is disclosed in one embodiment that has multiple identical sets of programmable functional elements, programmable routing resources, and majority voters that correct errors. The voters accept a mode input for a redundancy mode and a split mode. In the redundancy mode, the programmable functional elements are identical and are programmed identically so the voters produce an output corresponding to the majority of inputs that agree. In a split mode, each voter selects a particular programmable functional element output as the output of the voter. Therefore, in the split mode, the programmable functional elements can perform different functions, operate independently, and/or be connected together to process different parts of the same problem.

Exact Mesonic Eightfold Way From Dynamics and Confinement in Strongly Coupled Lattice QCD

NASA Astrophysics Data System (ADS)

Neto, A. Francisco; O'Carroll, M.; Faria da Veiga, P. A.

2009-01-01

We review our results on the exact determination of the mesonic eightfold way from first principles, directly from the quark-gluon dynamics. For this, we consider an imaginary-time functional integral formulation of 3 + 1 dimensional lattice QCD with Wilson action, three flavors, SU(3) f flavor symmetry and SU(3) c local gauge symmetry. We work in the strong coupling regime: a small hopping parameter κ>0 and a much smaller plaquette coupling β>0. By establishing a Feynman-Kac formula and a spectral representation to the two-meson correlation, we provide a rigorous connection between this correlation and the one-meson energy-momentum spectrum. The particle states can be labeled by the usual SU(3) f quantum numbers of total isospin I and its third-component I3, the quadratic Casimir C2 and, by a partial restoration of the continuous rotational symmetry on the lattice, as well as by the total spin J and its z-component Jz. We show that, up to near the two-meson energy threshold of ≈-4lnκ, the spectrum in the meson sector is given only by isolated dispersion curves of the eightfold way mesons. The mesons have all asymptotic mass of -2lnκ and, by deriving convergent expansions for the masses both in κ and β, we also show a κ mass splitting between the J=0,1 states. The splitting persists for β≠0. Our approach employs the decoupling of hyperplane method to uncover the basic excitations, complex analysis to determine the dispersion curves and a correlation subtraction method to show the curves are isolated. Using the latter and recalling our similar results for baryons, we also show confinement up to near the two-meson threshold.

Split-spectrum intensity-based optical fiber sensors for measurement of microdisplacement, strain, and pressure

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Plante, Angela J.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1996-05-01

A self-referencing technique compensating for fiber losses and source fluctuations in reflective air-gap intensity-based optical fiber sensors is described. A dielectric multilayer short-wave-pass filter is fabricated onto or attached to the output end face of the lead-in-lead-out multimode fiber. The incoming broadband light from a white light or a light-emitting diode is partially reflected at the filter. The transmitted light through the filter projects onto a mirror. The light returning from the reflecting mirror is recoupled into the lead-in-lead-out fiber. These two reflections from the filter and the reflecting mirror are spectrally separated at the detector end. The power ratio of these two reflections is insensitive to source fluctuations and fiber-bending loss. However, because the second optical signal depends on the air-gap separation between the end face of the lead-in-lead-out fiber and the reflecting mirror, the ratio provides the information on the air-gap length. A resolution of 0.13 mu m has been obtained over a microdisplacement measurement range of 0-254 mu m. The sensor is shown to be insensitive to both fiber-bending losses and variations in source power. Based on this approach, a fiber-strain sensor was fabricated with a multilayer interference filter directly fabricated on the end face of the fiber. A resolution of 13.4 microstrain was obtained over a measurement range of 0-20,000 microstrain with a gauge length of 10 mm. The split-spectrum method is also incorporated into a diaphragm displacement-based pressure sensor with a demonstrated resolution of 450 Pa over a measurement range of 0-0.8 MPa.

Zero field splitting fluctuations induced phase relaxation of Gd3+ in frozen solutions at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Raitsimring, A.; Dalaloyan, A.; Collauto, A.; Feintuch, A.; Meade, T.; Goldfarb, D.

2014-11-01

Distance measurements using double electron-electron resonance (DEER) and Gd3+ chelates for spin labels (GdSL) have been shown to be an attractive alternative to nitroxide spin labels at W-band (95 GHz). The maximal distance that can be accessed by DEER measurements and the sensitivity of such measurements strongly depends on the phase relaxation of Gd3+ chelates in frozen, glassy solutions. In this work, we explore the phase relaxation of Gd3+-DOTA as a representative of GdSL in temperature and concentration ranges typically used for W-band DEER measurements. We observed that in addition to the usual mechanisms of phase relaxation known for nitroxide based spin labels, GdSL are subjected to an additional phase relaxation mechanism that features an increase in the relaxation rate from the center to the periphery of the EPR spectrum. Since the EPR spectrum of GdSL is the sum of subspectra of the individual EPR transitions, we attribute this field dependence to transition dependent phase relaxation. Using simulations of the EPR spectra and its decomposition into the individual transition subspectra, we isolated the phase relaxation of each transition and found that its rate increases with |ms|. We suggest that this mechanism is due to transient zero field splitting (tZFS), where its magnitude and correlation time are scaled down and distributed as compared with similar situations in liquids. This tZFS induced phase relaxation mechanism becomes dominant (or at least significant) when all other well-known phase relaxation mechanisms, such as spectral diffusion caused by nuclear spin diffusion, instantaneous and electron spin spectral diffusion, are significantly suppressed by matrix deuteration and low concentration, and when the temperature is sufficiently low to disable spin lattice interaction as a source of phase relaxation.

Reduced TiO2-Graphene Oxide Heterostructure As Broad Spectrum-Driven Efficient Water-Splitting Photocatalysts.

PubMed

Li, Lihua; Yu, Lili; Lin, Zhaoyong; Yang, Guowei

2016-04-06

The reduced TiO2-graphene oxide heterostructure as an alternative broad spectrum-driven efficient water splitting photocatalyst has become a really interesting topic, however, its syntheses has many flaws, e.g., tedious experimental steps, time-consuming, small scale production, and requirement of various additives, for example, hydrazine hydrate is widely used as reductant to the reduction of graphene oxide, which is high toxicity and easy to cause the second pollution. For these issues, herein, we reported the synthesis of the reduced TiO2-graphene oxide heterostructure by a facile chemical reduction agent-free one-step laser ablation in liquid (LAL) method, which achieves extended optical response range from ultraviolet to visible and composites TiO(2-x) (reduced TiO2) nanoparticle and graphene oxide for promoting charge conducting. 30.64% Ti(3+) content in the reduced TiO2 nanoparticles induces the electronic reconstruction of TiO2, which results in 0.87 eV decrease of the band gap for the visible light absorption. TiO(2-x)-graphene oxide heterostructure achieved drastically increased photocatalytic H2 production rate, up to 23 times with respect to the blank experiment. Furthermore, a maximum H2 production rate was measured to be 16 mmol/h/g using Pt as a cocatalyst under the simulated sunlight irradiation (AM 1.5G, 135 mW/cm(2)), the quantum efficiencies were measured to be 5.15% for wavelength λ = 365 ± 10 nm and 1.84% for λ = 405 ± 10 nm, and overall solar energy conversion efficiency was measured to be 14.3%. These findings provided new insights into the broad applicability of this methodology for accessing fascinate photocatalysts.

New Photocatalysts for Hydrogen Production; Nuevos Fotocatalizadores para la Producción de Hidrógeno

DOE PAGES

García, Abraham; Cotto, María; Duconge, José; ...

2014-06-10

The use of hydrogen as replacement for fossil fuels, on which we depend today, is a matter of great relevance. The sustainable generation of hydrogen as fuel is relevant from an environmental and economic point of view. In this study we have explored new synthetic routes for developing new photocatalysts to be used in water splitting, for hydrogen production. Different techniques have been used to produce hydrogen, such as electrolysis, even though these processes have been found to be energetically non suitable. In this research various photocatalytic materials were presented as possible alternatives for using in water splitting processes. Characterizationmore » of the new synthesized materials has been done by using different experimental techniques including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), surface area BET, and X-ray Diffraction (XRD). The efficiency of the synthesized photocatalysts was determined by evaluating the hydrogen evolution by the photocatalytic water splitting reaction.« less

Fracturing And Liquid CONvection

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

2012-02-29

FALCON has been developed to enable simulation of the tightly coupled fluid-rock behavior in hydrothermal and engineered geothermal system (EGS) reservoirs, targeting the dynamics of fracture stimulation, fluid flow, rock deformation, and heat transport in a single integrated code, with the ultimate goal of providing a tool that can be used to test the viability of EGS in the United States and worldwide. Reliable reservoir performance predictions of EGS systems require accurate and robust modeling for the coupled thermal-hydrological-mechanical processes. Conventionally, these types of problems are solved using operator-splitting methods, usually by coupling a subsurface flow and heat transport simulatormore » with a solid mechanics simulator via input files. FALCON eliminates the need for using operator-splitting methods to simulate these systems, and the scalability of the underlying MOOSE architecture allows for simulating these tightly coupled processes at the reservoir scale, allowing for examination of the system as a whole (something the operator-splitting methodologies generally cannot do).« less

Photocatalytic hydrogen generation from hydriodic acid using methylammonium lead iodide in dynamic equilibrium with aqueous solution

NASA Astrophysics Data System (ADS)

Park, Sunghak; Chang, Woo Je; Lee, Chan Woo; Park, Sangbaek; Ahn, Hyo-Yong; Nam, Ki Tae

2017-01-01

The solar-driven splitting of hydrohalic acids (HX) is an important and fast growing research direction for H2 production. In addition to the hydrogen, the resulting chemicals (X2/X3-) can be used to propagate a continuous process in a closed cycle and are themselves useful products. Here we present a strategy for photocatalytic hydrogen iodide (HI) splitting using methylammonium lead iodide (MAPbI3) in an effort to develop a cost-effective and easily scalable process. Considering that MAPbI3 is a water-soluble ionic compound, we exploit the dynamic equilibrium of the dissolution and precipitation of MAPbI3 in saturated aqueous solutions. The I- and H+ concentrations of the aqueous solution are determined to be the critical parameters for the stabilization of the tetragonal MAPbI3 phase. Stable and efficient H2 production under visible light irradiation was demonstrated. The solar HI splitting efficiency of MAPbI3 was 0.81% when using Pt as a cocatalyst.

GEM: a dynamic tracking model for mesoscale eddies in the ocean

NASA Astrophysics Data System (ADS)

Li, Qiu-Yang; Sun, Liang; Lin, Sheng-Fu

2016-12-01

The Genealogical Evolution Model (GEM) presented here is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish between different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, the GEM first uses a two-dimensional (2-D) similarity vector (i.e., a pair of ratios of overlap area between two eddies to the area of each eddy) rather than a scalar to measure the similarity between eddies, which effectively solves the "missing eddy" problem (temporarily lost eddy in tracking). Second, for tracking when an eddy splits, the GEM uses both "parent" (the original eddy) and "child" (eddy split from parent) and the dynamic processes are described as the birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of eddies M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O(LM(N + 1)T). The tracking of each eddy is very smooth because we require that the snapshots of each eddy on adjacent days overlap one another. Although eddy splitting or merging is ubiquitous in the ocean, they have different geographic distributions in the North Pacific Ocean. Both the merging and splitting rates of the eddies are high, especially at the western boundary, in currents and in "eddy deserts". The GEM is useful not only for satellite-based observational data, but also for numerical simulation outputs. It is potentially useful for studying dynamic processes in other related fields, e.g., the dynamics of cyclones in meteorology.

Strong anisotropic optical conductivity in two-dimensional puckered structures: The role of the Rashba effect

NASA Astrophysics Data System (ADS)

Saberi-Pouya, S.; Vazifehshenas, T.; Salavati-fard, T.; Farmanbar, M.; Peeters, F. M.

2017-08-01

We calculate the optical conductivity of an anisotropic two-dimensional system with Rashba spin-flip excitation within the Kubo formalism. We show that the anisotropic Rashba effect caused by an external field significantly changes the magnitude of the spin splitting. Furthermore, we obtain an analytical expression for the longitudinal optical conductivity associated with interband transitions as a function of the frequency for arbitrary polarization angle. We find that the diagonal components of the optical conductivity tensor are direction dependent and the optical absorption spectrum exhibits a strongly anisotropic absorption window. The height and width of this absorption window are very sensitive to the anisotropy of the system. While the height of absorption peak increases with increasing effective mass anisotropy ratio, the peak intensity is larger when the light polarization is along the armchair direction. Moreover, the absorption peak width becomes broader as the density-of-states mass or Rashba interaction is enhanced. These features in the optical absorption spectrum can be used to determine parameters relevant for spintronics.

Resonant-Raman Intensities of N-layer Transition Metal Dichalcogenides from First Principles

NASA Astrophysics Data System (ADS)

Miranda, Henrique; Froehlicher, Guillaume; Lorchat, Ettienne; Fernique, François; Molina-Sánchez, Alejandro; Berciaud, Stéphane; Wirtz, Ludger

Transition metal dichalcogenides (TMDs) have interesting optical and electronic properties that make them good candidates for nano-engineering applications. Raman spectroscopy provides information about the vibrational modes and optical spectrum at the same time: when the laser energy is close to an electronic transition, the intensity is increased due to resonance. We investigate these effects combining different ab initio methods: we obtain ground-state and vibrational properties from density functional theory and the optical absorption spectrum using GW corrections and the Bethe-Salpeter equation to account for the excitonic effects which are known to play an important role in TMDs. Using a quasi-static finite differences approach, we calculate the dielectric susceptibility for different light polarizations and different phonon modes in order to determine the Raman tensor of TMDs, in particular of multi-layer and bulk MoTe2. We explain recent experimental results for the splitting of high-frequency modes and deviations from the non-resonant Raman model. We also give a brief outlook on possible improvements of the methodology.

Application of interferential correlation of spectrum to the detection of atmospheric pollutants

NASA Technical Reports Server (NTRS)

Fortunato, G.

1979-01-01

The general correlation principles for spectra and spectra derivatives are studied by using the Fourier transform of the spectral distribution of energy from a source illuminating a double beam interferometer with transverse splitting by dividing luminance. In this correlation technique, the use of such an interferometer has the advantage of greater luminosity as compared with a slit spectrometer. However, the correlation example indicates that it is necessary to adapt the correlator to the particular case considered, in order to obtain the best gain in the signal to noise ratio. In the case of sulfur dioxide detection, a very simple mounting which could be used in some interesting industrial applications was developed. This mounting can be used each time that the substance to be analyzed has a quasi-periodic absorption spectrum: in particular this is often the case with absorption spectra of gases, and a mounting identical to the one described for sulfur dioxide proved to be effective in the detection of nitrogen oxides.

Millimeter and submillimeter wave spectroscopy of propanal

NASA Astrophysics Data System (ADS)

Zingsheim, Oliver; Müller, Holger S. P.; Lewen, Frank; Jørgensen, Jes K.; Schlemmer, Stephan

2017-12-01

The rotational spectra of the two stable conformers syn- and gauche-propanal (CH3CH2CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first excited states associated with the aldehyde torsion and with the methyl torsion, respectively, of the syn-conformer were analyzed. The newly obtained spectroscopic parameters yield better predictions, thus fulfill sensitivity and resolution requirements in new astronomical observations in order to unambiguously assign pure rotational transitions of propanal. This is demonstrated on a radio astronomical spectrum from the Atacama Large Millimeter/submillimeter Array Protostellar Interferometric Line Survey (ALMA-PILS). In particular, an accurate description of observed splittings, caused by internal rotation of the methyl group in the syn-conformer and by tunneling rotation interaction from two stable degenerate gauche-conformers, is reported. The rotational spectrum of propanal is of additional interest because of its two large amplitude motions pertaining to the methyl and the aldehyde group, respectively.

Survey of contemporary trends in color image segmentation

NASA Astrophysics Data System (ADS)

Vantaram, Sreenath Rao; Saber, Eli

2012-10-01

In recent years, the acquisition of image and video information for processing, analysis, understanding, and exploitation of the underlying content in various applications, ranging from remote sensing to biomedical imaging, has grown at an unprecedented rate. Analysis by human observers is quite laborious, tiresome, and time consuming, if not infeasible, given the large and continuously rising volume of data. Hence the need for systems capable of automatically and effectively analyzing the aforementioned imagery for a variety of uses that span the spectrum from homeland security to elderly care. In order to achieve the above, tools such as image segmentation provide the appropriate foundation for expediting and improving the effectiveness of subsequent high-level tasks by providing a condensed and pertinent representation of image information. We provide a comprehensive survey of color image segmentation strategies adopted over the last decade, though notable contributions in the gray scale domain will also be discussed. Our taxonomy of segmentation techniques is sampled from a wide spectrum of spatially blind (or feature-based) approaches such as clustering and histogram thresholding as well as spatially guided (or spatial domain-based) methods such as region growing/splitting/merging, energy-driven parametric/geometric active contours, supervised/unsupervised graph cuts, and watersheds, to name a few. In addition, qualitative and quantitative results of prominent algorithms on several images from the Berkeley segmentation dataset are shown in order to furnish a fair indication of the current quality of the state of the art. Finally, we provide a brief discussion on our current perspective of the field as well as its associated future trends.

Connectivity-based parcellation reveals distinct cortico-striatal connectivity fingerprints in Autism Spectrum Disorder.

PubMed

Balsters, Joshua H; Mantini, Dante; Wenderoth, Nicole

2018-04-15

Autism Spectrum Disorder (ASD) has been associated with abnormal synaptic development causing a breakdown in functional connectivity. However, when measured at the macro scale using resting state fMRI, these alterations are subtle and often difficult to detect due to the large heterogeneity of the pathology. Recently, we outlined a novel approach for generating robust biomarkers of resting state functional magnetic resonance imaging (RS-fMRI) using connectivity based parcellation of gross morphological structures to improve single-subject reproducibility and generate more robust connectivity fingerprints. Here we apply this novel approach to investigating the organization and connectivity strength of the cortico-striatal system in a large sample of ASD individuals and typically developed (TD) controls (N=130 per group). Our results showed differences in the parcellation of the striatum in ASD. Specifically, the putamen was found to be one single structure in ASD, whereas this was split into anterior and posterior segments in an age, IQ, and head movement matched TD group. An analysis of the connectivity fingerprints revealed that the group differences in clustering were driven by differential connectivity between striatum and the supplementary motor area, posterior cingulate cortex, and posterior insula. Our approach for analysing RS-fMRI in clinical populations has provided clear evidence that cortico-striatal circuits are organized differently in ASD. Based on previous task-based segmentations of the striatum, we believe that the anterior putamen cluster present in TD, but not in ASD, likely contributes to social and language processes. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Kinetics and reaction coordinates of the reassembly of protein fragments via forward flux sampling.

PubMed

Borrero, Ernesto E; Contreras Martínez, Lydia M; DeLisa, Matthew P; Escobedo, Fernando A

2010-05-19

We studied the mechanism of the reassembly and folding process of two fragments of a split lattice protein by using forward flux sampling (FFS). Our results confirmed previous thermodynamics and kinetics analyses that suggested that the disruption of the critical core (of an unsplit protein that folds by a nucleation mechanism) plays a key role in the reassembly mechanism of the split system. For several split systems derived from a parent 48-mer model, we estimated the reaction coordinates in terms of collective variables by using the FFS least-square estimation method and found that the reassembly transition is best described by a combination of the total number of native contacts, the number of interchain native contacts, and the total conformational energy of the split system. We also analyzed the transition path ensemble obtained from FFS simulations using the estimated reaction coordinates as order parameters to identify the microscopic features that differentiate the reassembly of the different split systems studied. We found that in the fastest folding split system, a balanced distribution of the original-core amino acids (of the unsplit system) between protein fragments propitiates interchain interactions at early stages of the folding process. Only this system exhibits a different reassembly mechanism from that of the unsplit protein, involving the formation of a different folding nucleus. In the slowest folding system, the concentration of the folding nucleus in one fragment causes its early prefolding, whereas the second fragment tends to remain as a detached random coil. We also show that the reassembly rate can be either increased or decreased by tuning interchain cooperativeness via the introduction of a single point mutation that either strengthens or weakens one of the native interchain contacts (prevalent in the transition state ensemble). Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

A MEMS and agile optics-based dual-mode variable optical power splitter with no moving parts

NASA Astrophysics Data System (ADS)

Khwaja, Tariq S.; Suleman, Hamid; Reza, Syed Azer

2017-06-01

In this paper, we present a novel design of an optical power splitter. Owing to the inherent variable power split ratios that the proposed design delivers, it is ideal for use in communications, sensing and signal processing applications where variable power splitting is often quintessential. The proposed power splitter module is dual mode as it combines the use of a Micro-Electro-Mechanical Systems (MEMS) based Digital Micro-mirror Device (DMD) and an Electronically Controlled Tunable Lens (ECTL) to split the power of an input optical signal between two output ports - the designated port and the surplus port. The use of a reflective Digital Spatial Light Modulator (DSLM) such as the DMD provides a motion-free digital control of the split ratio between the two output ports. Although the digital step between two possible successive split ratios can be fairly minimal with the use of a high resolution DMD but it is a challenge to correctly ascertain the exact image pattern on the DMD to obtain any desired specific split ratio. To counter this challenge, we propose the synchronized use of a circular pattern on the DMD, which serves as a circular clear aperture with a tunable radius, and an ECTL. The radius of the circular pattern on the DMD provides a digital control of the split ratio between the two ports whereas the ECTL, depending on its controller, can provide either an analog or a digital control by altering the beam radius which is incident at the DMD circular pattern. The radius of the circular pattern on the DMD can be minimally changed by one micro-pixel thickness. Setting the radius of the circular pattern on the DMD to an appropriate value provides the closest "ball-park" split ratio whereas further tuning the ECTL aids in slightly altering from this digitally set value to obtain the exact desired split ratio in-between any two digitally-set successive split ratios that correspond to any clear aperture radius of the DMD pattern and its incremental minimal allowable change of one micropixel. We provide a detailed scheme to calculate the desired DMD aperture radius as well as the focal length setting of the ECTL to obtain any given split ratio. By setting tolerance limits on the split ratio, we also show that our method affords diversity by providing multiple possible solutions to achieve a desired optical power split ratio within the specified tolerances. We also demonstrate the validation of the proposed concept with initial experimental results and discussions. These experimental results show a repeatable splitter operation and the resulting power split ratios according to the theoretical predictions. With the experimental data, we also demonstrate the effectiveness of the method in obtaining any particular split ratio through different DMD and ECTL configurations with specific split ratio tolerance values.

Reactor Experiments at the University of Minnesota.

DTIC Science & Technology

1987-07-15

metallurgy; zinc, zinc oxide; solar thermal,’ solar Pi% thermoelectrochemical’ water splitting, separation devices; reactors e, ? 20. AeSiRACT (Continue oe...reported. Water splitting, recovery of hydrogen 4. and sulfur from hydrogen sulfide, electrolysis of zinc oxide in vapor and liquid phases, oil...CH4-CO2 reforming process. 2. Hydrogen production from water and the production of hydrogen and sulfur (or ammonia and sulfuric acid) from H2S. 3

Toward a High-Efficient Utilization of Solar Radiation by Quad-Band Solar Spectral Splitting.

PubMed

Cao, Feng; Huang, Yi; Tang, Lu; Sun, Tianyi; Boriskina, Svetlana V; Chen, Gang; Ren, Zhifeng

2016-12-01

The promising quad-band solar spectral splitter incorporates the properties of the optical filter and the spectrally selective solar thermal absorber can direct PV band to PV modules and absorb thermal band energy for thermal process with low thermal losses. It provides a new strategy for spectral splitting and offers potential ways for hybrid PVT system design. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dose Uniformity of Scored and Unscored Tablets: Application of the FDA Tablet Scoring Guidance for Industry.

PubMed

Ciavarella, Anthony B; Khan, Mansoor A; Gupta, Abhay; Faustino, Patrick J

This U.S. Food and Drug Administration (FDA) laboratory study examines the impact of tablet splitting, the effect of tablet splitters, and the presence of a tablet score on the dose uniformity of two model drugs. Whole tablets were purchased from five manufacturers for amlodipine and six for gabapentin. Two splitters were used for each drug product, and the gabapentin tablets were also split by hand. Whole and split amlodipine tablets were tested for content uniformity following the general chapter of the United States Pharmacopeia (USP) Uniformity of Dosage Units <905>, which is a requirement of the new FDA Guidance for Industry on tablet scoring. The USP weight variation method was used for gabapentin split tablets based on the recommendation of the guidance. All whole tablets met the USP acceptance criteria for the Uniformity of Dosage Units. Variation in whole tablet content ranged from 0.5 to 2.1 standard deviation (SD) of the percent label claim. Splitting the unscored amlodipine tablets resulted in a significant increase in dose variability of 6.5-25.4 SD when compared to whole tablets. Split tablets from all amlodipine drug products did not meet the USP acceptance criteria for content uniformity. Variation in the weight for gabapentin split tablets was greater than the whole tablets, ranging from 1.3 to 9.3 SD. All fully scored gabapentin products met the USP acceptance criteria for weight variation. Size, shape, and the presence or absence of a tablet score can affect the content uniformity and weight variation of amlodipine and gabapentin tablets. Tablet splitting produced higher variability. Differences in dose variability and fragmentation were observed between tablet splitters and hand splitting. These results are consistent with the FDA's concerns that tablet splitting can have an effect on the amount of drug present in a split tablet and available for absorption. Tablet splitting has become a very common practice in the United States and throughout the world. Tablets are often split to modify dose strength, make swallowing easier, and reduce cost to the consumer. To better address product quality for this widely used practice, the U.S. Food and Drug Administration (FDA) published a Guidance for Industry that addresses tablet splitting. The guidance provides testing criteria for scored tablets, which is a part of the FDA review process for drugs. The model drugs selected for this study were amlodipine and gabapentin, which have different sizes, shapes, and tablet scores. Whole and split amlodipine tablets were tested for drug content because of a concern that the low-dose strength may cause greater variability. Whole and split gabapentin tablets were tested for weight variation because of their higher dosage strength of 600 mg. All whole tablets met the acceptance criteria for the Uniformity of Dosage Units based on the guidance recommendations. When unscored amlodipine tablets were split by a splitter, all formulations did not meet the acceptance criteria. When fully scored gabapentin tablets were split by hand and by splitter, they met the acceptance criteria. The findings of this FDA study indicated physical characteristics such as size, shape, and tablet score can affect the uniformity of split tablets. © PDA, Inc. 2016.

Secure Communications in CIoT Networks with a Wireless Energy Harvesting Untrusted Relay.

PubMed

Hu, Hequn; Gao, Zhenzhen; Liao, Xuewen; Leung, Victor C M

2017-09-04

The Internet of Things (IoT) represents a bright prospect that a variety of common appliances can connect to one another, as well as with the rest of the Internet, to vastly improve our lives. Unique communication and security challenges have been brought out by the limited hardware, low-complexity, and severe energy constraints of IoT devices. In addition, a severe spectrum scarcity problem has also been stimulated by the use of a large number of IoT devices. In this paper, cognitive IoT (CIoT) is considered where an IoT network works as the secondary system using underlay spectrum sharing. A wireless energy harvesting (EH) node is used as a relay to improve the coverage of an IoT device. However, the relay could be a potential eavesdropper to intercept the IoT device's messages. This paper considers the problem of secure communication between the IoT device (e.g., sensor) and a destination (e.g., controller) via the wireless EH untrusted relay. Since the destination can be equipped with adequate energy supply, secure schemes based on destination-aided jamming are proposed based on power splitting (PS) and time splitting (TS) policies, called intuitive secure schemes based on PS (Int-PS), precoded secure scheme based on PS (Pre-PS), intuitive secure scheme based on TS (Int-TS) and precoded secure scheme based on TS (Pre-TS), respectively. The secure performances of the proposed schemes are evaluated through the metric of probability of successfully secure transmission ( P S S T ), which represents the probability that the interference constraint of the primary user is satisfied and the secrecy rate is positive. P S S T is analyzed for the proposed secure schemes, and the closed form expressions of P S S T for Pre-PS and Pre-TS are derived and validated through simulation results. Numerical results show that the precoded secure schemes have better P S S T than the intuitive secure schemes under similar power consumption. When the secure schemes based on PS and TS polices have similar P S S T , the average transmit power consumption of the secure scheme based on TS is lower. The influences of power splitting and time slitting ratios are also discussed through simulations.

The application of condensate water as an additional cooling media intermittently in condenser of a split air conditioning

NASA Astrophysics Data System (ADS)

Ardita, I. N.; Subagia, I. W. A.

2018-01-01

The condensate water produced by indoor a split air conditioning is usually not utilized and thrown away into the environment. The result of measurement shows that the temperature of condensate water produced by split air conditioning is quite low, that is 19-22 °C at the rate of 16-20 mL / min and it has PH balance. Under such conditions, Air Condensate produced by split air conditioning should still be recovered as an additional cooling medium on the condenser. This research will re-investigate the use of condensate water as an intermittent additional cooling of the condenser to increase the cooling capacity and performance of the air conditioning system. This research is done by experimental method whose implementation includes; designing and manufacturing of experimental equipment, mounting measuring tools, experimental data retrieval, data processing and yield analysis. The experimental results show that the use of condensate water as an intermittent additional cooling medium on split air conditioning condenser can increase the refrigeration effect about 2%, cooling capacity about 4% and 7% of COP system. Experimental results also show a decrease in power consumption in the system compressor about 3%

An Inexpensive Co-Intercalated Layered Double Hydroxide Composite with Electron Donor-Acceptor Character for Photoelectrochemical Water Splitting

PubMed Central

Zheng, Shufang; Lu, Jun; Yan, Dongpeng; Qin, Yumei; Li, Hailong; Evans, David G.; Duan, Xue

2015-01-01

In this paper, the inexpensive 4,4-diaminostilbene-2,2-disulfonate (DAS) and 4,4-dinitro-stilbene-2,2- disulfonate (DNS) anions with arbitrary molar ratios were successfully co-intercalated into Zn2Al-layered double hydroxides (LDHs). The DAS(50%)-DNS/LDHs composite exhibited the broad UV-visible light absorption and fluorescence quenching, which was a direct indication of photo-induced electron transfer (PET) process between the intercalated DAS (donor) and DNS (acceptor) anions. This was confirmed by the matched HOMO/LUMO energy levels alignment of the intercalated DAS and DNS anions, which was also compatible for water splitting. The DAS(50%)-DNS/LDHs composite was fabricated as the photoanode and Pt as the cathode. Under the UV-visible light illumination, the enhanced photo-generated current (4.67 mA/cm2 at 0.8 V vs. SCE) was generated in the external circuit, and the photoelectrochemical water split was realized. Furthermore, this photoelectrochemical water splitting performance had excellent crystalline, electrochemical and optical stability. Therefore, this novel inorganic/organic hybrid photoanode exhibited potential application prospect in photoelectrochemical water splitting. PMID:26174201

3D CFD Simulation of Plug Dynamics and Splitting through a Bifurcating Airway Model

NASA Astrophysics Data System (ADS)

Hoi, Cory; Raessi, Mehdi

2017-11-01

Respiratory distress syndrome (RDS) occurs because of pulmonary surfactant insufficiency in the lungs of preterm infants. The common medical procedure to treat RDS, called surfactant respiratory therapy (SRT), involves instilling liquid surfactant plugs into the pulmonary airways. SRT's effectiveness highly depends on the ability to deliver surfactant through the complex branching airway network. Experimental and computational efforts have been made to understand complex fluid dynamics of liquid plug motion through the lung airways in order to increase SRT's response rate. However, previous computational work used 2D airway model geometries and studied plug dynamics of a pre-split plug. In this work, we present CFD simulations of surfactant plug motion through a 3D bifurcating airway model. In our 3D y-tube geometry representing the lung airways, we are not limited by 2D or pre-split plug assumptions. The airway walls are covered with a pre-existing liquid film. Using a passive scalar marking the surfactant plug, the plug splitting and surfactant film deposition is studied under various airway orientations. Exploring the splitting process and liquid distribution in a 3D geometry will advance our understanding of surfactant delivery and will increase the effectiveness of SRT.

Library of synthetic transcriptional AND gates built with split T7 RNA polymerase mutants

PubMed Central

Shis, David L.; Bennett, Matthew R.

2013-01-01

The construction of synthetic gene circuits relies on our ability to engineer regulatory architectures that are orthogonal to the host’s native regulatory pathways. However, as synthetic gene circuits become larger and more complicated, we are limited by the small number of parts, especially transcription factors, that work well in the context of the circuit. The current repertoire of transcription factors consists of a limited selection of activators and repressors, making the implementation of transcriptional logic a complicated and component-intensive process. To address this, we modified bacteriophage T7 RNA polymerase (T7 RNAP) to create a library of transcriptional AND gates for use in Escherichia coli by first splitting the protein and then mutating the DNA recognition domain of the C-terminal fragment to alter its promoter specificity. We first demonstrate that split T7 RNAP is active in vivo and compare it with full-length enzyme. We then create a library of mutant split T7 RNAPs that have a range of activities when used in combination with a complimentary set of altered T7-specific promoters. Finally, we assay the two-input function of both wild-type and mutant split T7 RNAPs and find that regulated expression of the N- and C-terminal fragments of the split T7 RNAPs creates AND logic in each case. This work demonstrates that mutant split T7 RNAP can be used as a transcriptional AND gate and introduces a unique library of components for use in synthetic gene circuits. PMID:23479654

Production of arrays of chemically distinct nanolitre plugs via repeated splitting in microfluidic devices.

PubMed

Adamson, David N; Mustafi, Debarshi; Zhang, John X J; Zheng, Bo; Ismagilov, Rustem F

2006-09-01

This paper reports a method for the production of arrays of nanolitre plugs with distinct chemical compositions. One of the primary constraints on the use of plug-based microfluidics for large scale biological screening is the difficulty of fabricating arrays of chemically distinct plugs on the nanolitre scale. Here, using microfluidic devices with several T-junctions linked in series, a single input array of large (approximately 320 nL) plugs was split to produce 16 output arrays of smaller (approximately 20 nL) plugs; the composition and configuration of these arrays were identical to that of the input. This paper shows how the passive break-up of plugs in T-junction microchannel geometries can be used to produce a set of smaller-volume output arrays useful for chemical screening from a single large-volume array. A simple theoretical description is presented to describe splitting as a function of the Capillary number, the capillary pressure, the total pressure difference across the channel, and the geometric fluidic resistance. By accounting for these considerations, plug coalescence and plug-plug contamination can be eliminated from the splitting process and the symmetry of splitting can be preserved. Furthermore, single-outlet splitting devices were implemented with both valve- and volume-based methods for coordinating the release of output arrays. Arrays of plugs containing commercial sparse matrix screens were obtained from the presented splitting method and these arrays were used in protein crystallization trials. The techniques presented in this paper may facilitate the implementation of high-throughput chemical and biological screening.

Library of synthetic transcriptional AND gates built with split T7 RNA polymerase mutants.

PubMed

Shis, David L; Bennett, Matthew R

2013-03-26

The construction of synthetic gene circuits relies on our ability to engineer regulatory architectures that are orthogonal to the host's native regulatory pathways. However, as synthetic gene circuits become larger and more complicated, we are limited by the small number of parts, especially transcription factors, that work well in the context of the circuit. The current repertoire of transcription factors consists of a limited selection of activators and repressors, making the implementation of transcriptional logic a complicated and component-intensive process. To address this, we modified bacteriophage T7 RNA polymerase (T7 RNAP) to create a library of transcriptional AND gates for use in Escherichia coli by first splitting the protein and then mutating the DNA recognition domain of the C-terminal fragment to alter its promoter specificity. We first demonstrate that split T7 RNAP is active in vivo and compare it with full-length enzyme. We then create a library of mutant split T7 RNAPs that have a range of activities when used in combination with a complimentary set of altered T7-specific promoters. Finally, we assay the two-input function of both wild-type and mutant split T7 RNAPs and find that regulated expression of the N- and C-terminal fragments of the split T7 RNAPs creates AND logic in each case. This work demonstrates that mutant split T7 RNAP can be used as a transcriptional AND gate and introduces a unique library of components for use in synthetic gene circuits.

Multi-photon Rabi oscillations in high spin paramagnetic impurity

NASA Astrophysics Data System (ADS)

Bertaina, S.; Groll, N.; Chen, L.; Chiorescu, I.

2011-10-01

We report on multiple photon monochromatic quantum oscillations (Rabi oscillations) observed by pulsed EPR (Electron Paramagnetic Resonance) of Mn2+ (S = 5/2) impurities in MgO. We find that when the microwave magnetic field is similar or large than the anisotropy splitting, the Rabi oscillations have a spectrum made of many frequencies not predicted by the S = l/2 Rabi model. We show that these new frequencies come from multiple photon coherent manipulation of the multi-level spin impurity. We develop a model based on the crystal field theory and the rotating frame approximation, describing the observed phenomenon with a very good agreement.

Loss-compensation technique using a split-spectrum approach for optical fiber air-gap intensity-based sensors

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1993-03-01

A self-referencing technique compensating for fiber losses and source fluctuations in air-gap intensity-based optical fiber sensors is described and demonstrated. A resolution of 0.007 micron has been obtained over a measurement range of 0-250 microns for an intensity-based displacement sensor using this referencing technique. The sensor is shown to have minimal sensitivity to fiber bending losses and variations in the LED input power. A theoretical model for evaluation of step-index multimode optical fiber splice is proposed. The performance of the sensor as a displacement sensor agrees well with the theoretical analysis.

Application of optical coherence tomography attenuation imaging for quantification of optical properties in medulloblastoma

NASA Astrophysics Data System (ADS)

Vuong, Barry; Skowron, Patryk; Kiehl, Tim-Rasmus; Kyan, Matthew; Garzia, Livia; Genis, Helen; Sun, Cuiru; Taylor, Michael D.; Yang, Victor X. D.

2015-03-01

The hemodynamic environment is known to play a crucial role in the progression, rupture, and treatment of intracranial aneurysms. Currently there is difficulty assessing and measuring blood flow profiles in vivo. An emerging high resolution imaging modality known as split spectrum Doppler optical coherence tomography (ssDOCT) has demonstrated the capability to quantify hemodynamic patterns as well as arterial microstructural changes. In this study, we present a novel in vitro method to acquire precise blood flow patterns within a patient- specific aneurysm silicone flow models using ssDOCT imaging. Computational fluid dynamics (CFD) models were generated to verify ssDOCT results.

Unpaired Majorana modes in Josephson-Junction Arrays with gapless bulk excitations

DOE PAGES

Pino, M.; Tsvelik, A.; Ioffe, L. B.

2015-11-06

In this study, the search for Majorana bound states in solid-state physics has been limited to materials that display a gap in their bulk spectrum. We show that such unpaired states appear in certain quasi-one-dimensional Josephson-junction arrays with gapless bulk excitations. The bulk modes mediate a coupling between Majorana bound states via the Ruderman-Kittel-Yosida-Kasuya mechanism. As a consequence, the lowest energy doublet acquires a finite energy difference. For a realistic set of parameters this energy splitting remains much smaller than the energy of the bulk eigenstates even for short chains of length L~10.

Tunable Multiple Plasmon-Induced Transparencies Based on Asymmetrical Graphene Nanoribbon Structures

PubMed Central

Lu, Chunyu; Wang, Jicheng; Yan, Shubin; Hu, Zheng-Da; Zheng, Gaige; Yang, Liu

2017-01-01

We present plasmonic devices, consisting of periodic arrays of graphene nanoribbons (GNRs) and a graphene sheet waveguide, to achieve controllable plasmon-induced transparency (PIT) by numerical simulation. We analyze the bright and dark elements of the GNRs and graphene-sheet waveguide structure. Results show that applying the gate voltage can electrically tune the PIT spectrum. Adjusting the coupling distance and widths of GNRs directly results in a shift of transmission dips. In addition, increased angle of incidence causes the transmission to split into multiple PIT peaks. We also demonstrate that PIT devices based on graphene plasmonics may have promising applications as plasmonic sensors in nanophotonics. PMID:28773062

Spin wave spectra in perpendicularly magnetized permalloy rings

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

Zhou, X.; Ding, J.; Adeyeye, A. O., E-mail: eleaao@nus.edu.sg

2015-03-16

The dynamic behavior of perpendicularly magnetized permalloy circular rings is systematically investigated as a function of film thickness using broadband field modulated ferromagnetic resonance spectroscopy. We observed the splitting of one spin wave mode into a family of dense resonance peaks for the rings, which is markedly different from the single mode observed for continuous films of the same thickness. As the excitation frequency is increased, the mode family observed for the rings gradually converges into one mode. With the increase in the film thickness, a sparser spectrum of modes is observed. Our experimental results are in qualitative agreement withmore » the dynamic micromagnetic simulations.« less

Precision spectral manipulation of optical pulses using a coherent photon echo memory.

PubMed

Buchler, B C; Hosseini, M; Hétet, G; Sparkes, B M; Lam, P K

2010-04-01

Photon echo schemes are excellent candidates for high efficiency coherent optical memory. They are capable of high-bandwidth multipulse storage, pulse resequencing and have been shown theoretically to be compatible with quantum information applications. One particular photon echo scheme is the gradient echo memory (GEM). In this system, an atomic frequency gradient is induced in the direction of light propagation leading to a Fourier decomposition of the optical spectrum along the length of the storage medium. This Fourier encoding allows precision spectral manipulation of the stored light. In this Letter, we show frequency shifting, spectral compression, spectral splitting, and fine dispersion control of optical pulses using GEM.

Caudal Duplication Syndrome: the Vital Role of a Multidisciplinary Approach and Staged Correction

PubMed Central

Samuk, Inbal; Levitt, Marc; Dlugy, Elena; Kravarusic, Dragan; Ben-Meir, David; Rajz, Gustavo; Konen, Osnat; Freud, Enrique

2015-01-01

Caudal duplication syndrome is a rare entity that describes the association between congenital anomalies involving caudal structures and may have a wide spectrum of clinical manifestations. A full-term male presented with combination of anomalies including anorectal malformation, duplication of the colon and lower urinary tract, split of the lower spine, and lipomyelomeningocele with tethering of the cord. We report this exceptional case of caudal duplication syndrome with special emphasis on surgical strategy and approach combining all disciplines involved. The purpose of this report is to present the pathology, assessment, and management strategy of this complex case. PMID:28018799

Possible 6-qubit NMR quantum computer device material; simulator of the NMR line width

NASA Astrophysics Data System (ADS)

Hashi, K.; Kitazawa, H.; Shimizu, T.; Goto, A.; Eguchi, S.; Ohki, S.

2002-12-01

For an NMR quantum computer, splitting of an NMR spectrum must be larger than a line width. In order to find a best device material for a solid-state NMR quantum computer, we have made a simulation program to calculate the NMR line width due to the nuclear dipole field by the 2nd moment method. The program utilizes the lattice information prepared by commercial software to draw a crystal structure. By applying this program, we can estimate the NMR line width due to the nuclear dipole field without measurements and find a candidate material for a 6-qubit solid-state NMR quantum computer device.

Analysis of Heme Iron Coordination in DGCR8: The Heme-Binding Component of the Microprocessor Complex.

PubMed

Girvan, Hazel M; Bradley, Justin M; Cheesman, Myles R; Kincaid, James R; Liu, Yilin; Czarnecki, Kazimierz; Fisher, Karl; Leys, David; Rigby, Stephen E J; Munro, Andrew W

2016-09-13

DGCR8 is the RNA-binding partner of the nuclease Drosha. Their complex (the "Microprocessor") is essential for processing of long, primary microRNAs (pri-miRNAs) in the nucleus. Binding of heme to DGCR8 is essential for pri-miRNA processing. On the basis of the split Soret ultraviolet-visible (UV-vis) spectrum of ferric DGCR8, bis-thiolate sulfur (cysteinate, Cys(-)) heme iron coordination of DGCR8 heme iron was proposed. We have characterized DGCR8 heme ligation using the Δ276 DGCR8 variant and combined electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), electron nuclear double resonance, resonance Raman, and electronic absorption spectroscopy. These studies indicate DGCR8 bis-Cys heme iron ligation, with conversion from bis-thiolate (Cys(-)/Cys(-)) axial coordination in ferric DGCR8 to bis-thiol (CysH/CysH) coordination in ferrous DGCR8. Pri-miRNA binding does not perturb ferric DGCR8's optical spectrum, consistent with the axial ligand environment being separated from the substrate-binding site. UV-vis absorption spectra of the Fe(II) and Fe(II)-CO forms indicate discrete species exhibiting peaks with absorption coefficients substantially larger than those for ferric DGCR8 and that previously reported for a ferrous form of DGCR8. Electron-nuclear double resonance spectroscopy data exclude histidine or water as axial ligands for ferric DGCR8 and favor bis-thiolate coordination in this form. UV-vis MCD and near-infrared MCD provide data consistent with this conclusion. UV-vis MCD data for ferrous DGCR8 reveal features consistent with bis-thiol heme iron coordination, and resonance Raman data for the ferrous-CO form are consistent with a thiol ligand trans to the CO. These studies support retention of DGCR8 cysteine coordination upon reduction, a conclusion distinct from those of previous studies of a different ferrous DGCR8 isoform.

The Jet-Cooled High-Resolution IR Spectrum of Formic Acid Cyclic Dimer

NASA Astrophysics Data System (ADS)

Goubet, Manuel; Bteich, Sabath; Huet, Therese R.; Pirali, Olivier; Asselin, Pierre; Soulard, Pascale; Jabri, Atef; Roy, P.; Georges, Robert

2017-06-01

As the simplest carboxylic acid, formic acid (FA) is an excellent model molecule to investigate the general properties of carboxylic acids. FA is also an atmospherically and astrophysically relevant molecule. It is well known that its dimeric form is predominant in the gas phase at temperatures below 423 K. The cyclic conformation of the dimer (FACD) is an elementary system to be understood for the concerted hydrogen transfer through equivalent hydrogen bonds, an essential process within biomolecules. The IR range is a crucial spectral region, particularly the far-IR, as it gives a direct access to the intermolecular vibrational modes involved in this process. Moreover, due to its centrosymmetric conformation, the FACD exhibits no pure rotation spectrum and, due to spectral line congestion and Doppler broadening, IR bands cannot be rotationally resolved at room temperature. So far, only parts of the ν_{5}-GS band (C-O stretch) have been observed under jet-cooled conditions using laser techniques. We present here six rotationally resolved IR bands of FACD recorded under jet-cooled conditions using the Jet-AILES apparatus and the QCL spectrometer at MONARIS, including the far-IR ν_{24}-GS band (intermolecular in-plane bending). Splitting due to vibration-rotation-tunneling motions are clearly observed. A full spectral analysis is in progress starting from the GS constants obtained by Goroya et al. and with the support of electronic structure calculations. T. Miyazawa and K. S. Pitzer, J. Am. Chem. Soc. 81, 74, 1959 R. Georges, M. Freytes, D. Hurtmans, I. Kleiner, J. Vander Auwera, M. Herman, Chem. Phys. 305, 187, 2004 M. Ortlieb and M. Havenith, J. Phys. Chem. A 111, 7355, 2007; K. G. Goroya, Y. Zhu, P. Sun and C. Duan, J. Chem. Phys. 140, 164311, 2014 This work is supported by the CaPPA project (Chemical and Physical Properties of the Atmosphere) ANR-11-LABX-0005-01

Geometric & radiometric vignetting associated with a 72-facet, off-axis, polygon mirror for swept source optical coherence tomography (SS-OCT)

NASA Astrophysics Data System (ADS)

Everson, Michael; Duma, Virgil-Florin; Dobre, George

2017-01-01

Optical Coherence Tomography (OCT) has a broad range of applications in 2D and volumetric imaging of micron scale structures typically used on inaccessible objects such as the retina of the eye. This report focuses on Swept Source OCT (SS-OCT), favoured for its faster scanning speeds and therefore faster data acquisition (highly favourable when imaging live patients). SS-OCT relies on the scanning of a narrow laser line at speeds typically in excess of 100 kHz. We have employed ZemaxTM ray tracing software to simulate one method of splitting the spectrum of a broadband, near-infrared source, into its component wavelengths by reflecting the spectrum from an off-axis, 72-facet polygon mirror at a frequency of 48 kHz. We specifically addressed the geometric and radiometric vignetting associated with the reflected spectrum off an individual mirrored facet and how this may impose limitations to the incident beam size and hence lead to a loss in the power available from the source. It was found that for certain configurations up to 44% of the light was lost at the edges of the spectrum due to both radiometric and geometric vignetting, which may result in an effective swept range of <50 nm from an initial bandwidth of 100 nm. Our simulations account for real refractive errors and losses in the beam caused by lens aberrations, and produce a model of the sampling function of wavelength against time.

Yttrium oxide based three dimensional metamaterials for visible light cloaking

NASA Astrophysics Data System (ADS)

Rai, Pratyush; Kumar, Prashanth S.; Varadan, Vijay K.; Ruffin, Paul; Brantley, Christina; Edwards, Eugene

2014-04-01

Metamaterial with negative refractive index is the key phenomenon behind the concept of a cloaking device to hide an object from light in visible spectrum. Metamaterials made of two and three dimensional lattices of periodically placed electromagnetic resonant cells can achieve absorption and propagation of incident electromagnetic radiation as confined electromagnetic fields confined to a waveguide as surface plasmon polaritons, which can be used for shielding an object from in-tune electromagnetic radiation. The periodicity and dimensions of resonant cavity determine the frequency, which are very small as compared to the wavelength of incident light. Till now the phenomena have been demonstrated only for lights in near infrared spectrum. Recent advancements in fabrication techniques have made it possible to fabricate array of three dimensional nanostructures with cross-sections as small as 25 nm that are required for negative refractive index for wavelengths in visible light spectrum of 400-700 nm and for wider view angle. Two types of metamaterial designs, three dimensional concentric split ring and fishnet, are considered. Three dimensional structures consisted of metal-dielectric-metal stacks. The metal is silver and dielectric is yttrium oxide, other than conventional materials such as FR4 and Duroid. High κ dielectric and high refractive index as well as large crystal symmetry of Yttrium oxide has been investigated as encapsulating medium. Dependence of refractive index on wavelength and bandwidth of negative refractive index region are analyzed for application towards cloaking from light in visible spectrum.