Time-resolved luminescent spectroscopy of YAG:Ce single crystal and single crystalline films

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Vozniak, T.; Puzikov, V.; Danko, A.; Nizhankovski, S.

2010-01-01

The peculiarities of the luminescence and energy transfer from YAG host to the emission centers formed by the Y Al antisite defects and Ce 3+ ions have been studied in YAG:Ce single crystals, grown from the melt by modified Bridgman method in Ar and CO 2 + H 2 atmospheres, and YAG:Ce single crystalline film, grown by liquid phase epitaxy method, using the comparative time-resolved luminescent spectroscopy under excitation by synchrotron radiation in the range of fundamental adsorption of this garnet.

Broadband time-resolved elliptical crystal spectrometer for X-ray spectroscopic measurements in laser-produced plasmas

International Nuclear Information System (INIS)

Wang Rui-Rong; Jia Guo; Fang Zhi-Heng; Wang Wei; Meng Xiang-Fu; Xie Zhi-Yong; Zhang Fan

2014-01-01

The X-ray spectrometer used in high-energy-density plasma experiments generally requires both broad X-ray energy coverage and high temporal, spatial, and spectral resolutions for overcoming the difficulties imposed by the X-ray background, debris, and mechanical shocks. By using an elliptical crystal together with a streak camera, we resolve this issue at the SG-II laser facility. The carefully designed elliptical crystal has a broad spectral coverage with high resolution, strong rejection of the diffuse and/or fluorescent background radiation, and negligible source broadening for extended sources. The spectra that are Bragg reflected (23° < θ < 38°) from the crystal are focused onto a streak camera slit 18 mm long and about 80 μm wide, to obtain a time-resolved spectrum. With experimental measurements, we demonstrate that the quartz(1011) elliptical analyzer at the SG-II laser facility has a single-shot spectral range of (4.64–6.45) keV, a typical spectral resolution of E/ΔE = 560, and an enhanced focusing power in the spectral dimension. For titanium (Ti) data, the lines of interest show a distribution as a function of time and the temporal variations of the He-α and Li-like Ti satellite lines and their spatial profiles show intensity peak red shifts. The spectrometer sensitivity is illustrated with a temporal resolution of better than 25 ps, which satisfies the near-term requirements of high-energy-density physics experiments. (atomic and molecular physics)

Crystallization and melting behavior of poly(ethylene oxide) and its blend with styrene-based ionomer using time-resolved SAXS/WAXS experiments

Energy Technology Data Exchange (ETDEWEB)

Slusarczyk, CzesLaw, E-mail: cslusarczyk@ath.bielsko.pl [Institute of Textile Engineering and Polymer Materials, University of Bielsko-BiaLa, ul. Willowa 2, 43-309 Bielsko-BiaLa (Poland)

2011-10-15

Time-resolved synchrotron wide- and small-angle X-ray scattering experiments were used to investigate the crystallization behavior and microstructure development of neat poly(ethylene oxide) (PEO) and its 50/50 blend with ionomer containing 6.4 mol% of sodium acrylate. The apparent lateral crystal sizes D{sub (120)} and D{sub (112)/(004)} were derived from the WAXS profiles. It was found that D{sub (120)} and D{sub (112)/(004)} of PEO in the blend are almost independent of temperature and are smaller when compared to those of neat PEO sample. The evolution of morphological parameters extracted from time-resolved SAXS profiles such as the long period L, the lamellar crystal thickness l{sub C} and the amorphous layer thickness l{sub A}, shows that the crystallization process of neat PEO follows the nucleation theory. The lamellar crystal thickness l{sub C} shows a single linear dependence on inverse supercooling, over the whole temperature range investigated. In contrast, the crystallization process of PEO in the blend (i.e. in the presence of interactions with the ionomer) follows the nucleation theory only in the narrow supercooling range. It was found also that the morphology of the blend consists of a broad population of lamellar crystal thicknesses. During heating lamellae melt in the reversed sequence of their formation.

Energetics of hydrogen bonding in proteins: a model compound study.

OpenAIRE

Habermann, S. M.; Murphy, K. P.

1996-01-01

Differences in the energetics of amide-amide and amide-hydroxyl hydrogen bonds in proteins have been explored from the effect of hydroxyl groups on the structure and dissolution energetics of a series of crystalline cyclic dipeptides. The calorimetrically determined energetics are interpreted in light of the crystal structures of the studied compounds. Our results indicate that the amide-amide and amide-hydroxyl hydrogen bonds both provide considerable enthalpic stability, but that the amide-...

Mechanisms and energetics of surface atomic processes

International Nuclear Information System (INIS)

Tsong, T.T.

1991-01-01

The energies involved in various surface atomic processes such as surface diffusion, the binding of small atomic clusters on the surface, the interaction between two adsorbed atoms, the dissociation of an atom from a small cluster or from a surface layer, the binding of kink size atoms or atoms at different adsorption sites to the surface etc., can be derived from an analysis of atomically resolved field ion microscope images and a kinetic energy measurement of low temperature field desorbed ions using the time-of-flight atom-probe field ion microscope. These energies can be used to compare with theories and to understand the transport of atoms on the surface in atomic reconstructions, epitaxial growth of surface layers and crystal growth, adsorption layer superstructure formation, and also why an atomic ordering or atomic reconstruction at the surface is energetically favored. Mechanisms of some of the surface atomic processes are also clarified from these quantitative, atomic resolution studies. In this paper work in this area is bris briefly reviewed

Energetically Unfavorable Amide Conformations for N6-Acetyllysine Side Chains in Refined Protein Structures

Science.gov (United States)

Genshaft, Alexander; Moser, Joe-Ann S.; D'Antonio, Edward L.; Bowman, Christine M.; Christianson, David W.

2013-01-01

The reversible acetylation of lysine to form N6-acetyllysine in the regulation of protein function is a hallmark of epigenetics. Acetylation of the positively charged amino group of the lysine side chain generates a neutral N-alkylacetamide moiety that serves as a molecular “switch” for the modulation of protein function and protein-protein interactions. We now report the analysis of 381 N6-acetyllysine side chain amide conformations as found in 79 protein crystal structures and 11 protein NMR structures deposited in the Protein Data Bank (PDB) of the Research Collaboratory for Structural Bioinformatics. We find that only 74.3% of N6-acetyllysine residues in protein crystal structures and 46.5% in protein NMR structures contain amide groups with energetically preferred trans or generously trans conformations. Surprisingly, 17.6% of N6-acetyllysine residues in protein crystal structures and 5.3% in protein NMR structures contain amide groups with energetically unfavorable cis or generously cis conformations. Even more surprisingly, 8.1% of N6-acetyllysine residues in protein crystal structures and 48.2% in NMR structures contain amide groups with energetically prohibitive twisted conformations that approach the transition state structure for cis-trans isomerization. In contrast, 109 unique N-alkylacetamide groups contained in 84 highly-accurate small molecule crystal structures retrieved from the Cambridge Structural Database exclusively adopt energetically preferred trans conformations. Therefore, we conclude that cis and twisted N6-acetyllysine amides in protein structures deposited in the PDB are erroneously modeled due to their energetically unfavorable or prohibitive conformations. PMID:23401043

A crossover in anisotropic nanomechanochemistry of van der Waals crystals

International Nuclear Information System (INIS)

Shimamura, Kohei; Misawa, Masaaki; Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya; Shimojo, Fuyuki

2015-01-01

In nanoscale mechanochemistry, mechanical forces selectively break covalent bonds to essentially control chemical reactions. An archetype is anisotropic detonation of layered energetic molecular crystals bonded by van der Waals (vdW) interactions. Here, quantum molecular dynamics simulations reveal a crossover of anisotropic nanomechanochemistry of vdW crystal. Within 10 −13 s from the passage of shock front, lateral collision produces NO 2 via twisting and bending of nitro-groups and the resulting inverse Jahn-Teller effect, which is mediated by strong intra-layer hydrogen bonds. Subsequently, as we transition from heterogeneous to homogeneous mechanochemical regimes around 10 −12 s, shock normal to multilayers becomes more reactive, producing H 2 O assisted by inter-layer N-N bond formation. These time-resolved results provide much needed atomistic understanding of nanomechanochemistry that underlies a wider range of technologies

A crossover in anisotropic nanomechanochemistry of van der Waals crystals

Energy Technology Data Exchange (ETDEWEB)

Shimamura, Kohei [Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Graduate School of System Informatics, Kobe University, Kobe 657-8501 (Japan); Misawa, Masaaki [Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Li, Ying [Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Shimojo, Fuyuki [Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan)

2015-12-07

In nanoscale mechanochemistry, mechanical forces selectively break covalent bonds to essentially control chemical reactions. An archetype is anisotropic detonation of layered energetic molecular crystals bonded by van der Waals (vdW) interactions. Here, quantum molecular dynamics simulations reveal a crossover of anisotropic nanomechanochemistry of vdW crystal. Within 10{sup −13} s from the passage of shock front, lateral collision produces NO{sub 2} via twisting and bending of nitro-groups and the resulting inverse Jahn-Teller effect, which is mediated by strong intra-layer hydrogen bonds. Subsequently, as we transition from heterogeneous to homogeneous mechanochemical regimes around 10{sup −12} s, shock normal to multilayers becomes more reactive, producing H{sub 2}O assisted by inter-layer N-N bond formation. These time-resolved results provide much needed atomistic understanding of nanomechanochemistry that underlies a wider range of technologies.

Energetic mid-IR femtosecond pulse generation by self-defocusing soliton-induced dispersive waves in a bulk quadratic nonlinear crystal

DEFF Research Database (Denmark)

Zhou, Binbin; Guo, Hairun; Bache, Morten

2015-01-01

Generating energetic femtosecond mid-IR pulses is crucial for ultrafast spectroscopy, and currently relies on parametric processes that, while efficient, are also complex. Here we experimentally show a simple alternative that uses a single pump wavelength without any pump synchronization and with...... by using large-aperture crystals. The technique can readily be implemented with other crystals and laser wavelengths, and can therefore potentially replace current ultrafast frequency-conversion processes to the mid-IR....... and without critical phase-matching requirements. Pumping a bulk quadratic nonlinear crystal (unpoled LiNbO3 cut for noncritical phase-mismatched interaction) with sub-mJ near-IR 50-fs pulses, tunable and broadband (∼ 1,000 cm−1) mid-IR pulses around 3.0 μm are generated with excellent spatio-temporal pulse...... quality, having up to 10.5 μJ energy (6.3% conversion). The mid-IR pulses are dispersive waves phase-matched to near-IR self-defocusing solitons created by the induced self-defocusing cascaded nonlinearity. This process is filament-free and the input pulse energy can therefore be scaled arbitrarily...

Electronic structure of superconducting Bi2212 crystal by angle resolved ultra violet photoemission

International Nuclear Information System (INIS)

Saini, N.L.; Shrivastava, P.; Garg, K.B.

1993-01-01

The electronic structure of a high quality superconducting Bi 2 Sr 2 CaCu 2 Osub(8+δ) (Bi2212) single crystal is studied by angle resolved ultra violet photoemission (ARUPS) using He I (21.2 eV). Our results appear to show two bands crossing the Fermi level in ΓX direction of the Brillouin zone as reported by Takahashi et al. The bands at higher binding energy do not show any appreciable dispersion. The nature of the states near the Fermi level is discussed and the observed band structure is compared with the band structure calculations. (author)

Scintillator Based Energetic Ion Loss Diagnostic for the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Darrow, D.S.

2007-01-01

A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss to several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera

Scintillator Based Energetic Ion Loss Diagnostic for the National Spherical Torus Experiment

Energy Technology Data Exchange (ETDEWEB)

D.S. Darrow

2007-07-02

A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss to several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera.

Energetic materials under high pressures and temperatures: stability, polymorphism and decomposition of RDX

International Nuclear Information System (INIS)

Dreger, Z A

2012-01-01

A recent progress in understanding the response of energetic crystal of cyclotrimethylene trinitramine (RDX) to high pressures and temperatures is summarized. The optical spectroscopy and imaging studies under static compression and high temperatures provided new insight into phase diagram, polymorphism and decomposition mechanisms at pressures and temperatures relevant to those under shock compression. These results have been used to aid the understanding of processes under shock compression, including the shock-induced phase transition and identification of the crystal phase at decomposition. This work demonstrates that studies under static compression and high temperatures provide important complementary route for elucidating the physical and chemical processes in shocked energetic crystals.

Time-resolved broadband analysis of slow-light propagation and superluminal transmission of electromagnetic waves in three-dimensional photonic crystals

NARCIS (Netherlands)

Gómez Rivas, J.; Farré Benet, A.; Niehusmann, J.; Haring Bolivar, P.; Kurz, H.

2005-01-01

A time-resolved analysis of the amplitude and phase of THz pulses propagating through three-dimensional photonic crystals is presented. Single-cycle pulses of THz radiation allow measurements over a wide frequency range, spanning more than an octave below, at and above the bandgap of strongly

Study of the Bulk Charge Carrier Dynamics in Anatase and Rutile TiO2 Single Crystals by Femtosecond Time Resolved Spectroscopy

KAUST Repository

Maity, Partha; Mohammed, Omar F.; Katsiev, Khabiboulakh; Idriss, Hicham

2018-01-01

as the best model for fundamental studies. Their ultrafast charge carrier dynamics especially on TiO2 anatase single crystal (the most active phase) are unresolved. Here femtosecond time resolved spectroscopy (TRS) was carried out to explore the dynamics

Crystallization Formulation Lab

Data.gov (United States)

Federal Laboratory Consortium — The Crystallization Formulation Lab fills a critical need in the process development and optimization of current and new explosives and energetic formulations. The...

Phase-resolved pulse propagation through metallic photonic crystal slabs: plasmonic slow light

Science.gov (United States)

Schönhardt, Anja; Nau, Dietmar; Bauer, Christina; Christ, André; Gräbeldinger, Hedi; Giessen, Harald

2017-03-01

We characterized the electromagnetic field of ultra-short laser pulses after propagation through metallic photonic crystal structures featuring photonic and plasmonic resonances. The complete pulse information, i.e. the envelope and phase of the electromagnetic field, was measured using the technique of cross-correlation frequency resolved optical gating. In good agreement, measurements and scattering matrix simulations show a dispersive behaviour of the spectral phase at the position of the resonances. Asymmetric Fano-type resonances go along with asymmetric phase characteristics. Furthermore, the spectral phase is used to calculate the dispersion of the sample and possible applications in dispersion compensation are investigated. Group refractive indices of 700 and 70 and group delay dispersion values of 90 000 fs2 and 5000 fs2 are achieved in transverse electric and transverse magnetic polarization, respectively. The behaviour of extinction and spectral phase can be understood from an intuitive model using the complex transmission amplitude. An associated depiction in the complex plane is a useful approach in this context. This method promises to be valuable also in photonic crystal and filter design, for example, with regards to the symmetrization of the resonances. This article is part of the themed issue 'New horizons for nanophotonics'.

Time-resolved X-ray diffraction studies of laser-induced acoustic wave propagation in bilayer metallic thin crystals

Energy Technology Data Exchange (ETDEWEB)

Er, Ali Oguz [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, Kentucky 42101 (United States); Tang, Jau, E-mail: jautang@gate.sinica.edu.tw, E-mail: prentzepis@ece.tamu.edu [Research Center for Applied Sciences Academia Sinica, Taipei, Taiwan (China); Chen, Jie [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Rentzepis, Peter M., E-mail: jautang@gate.sinica.edu.tw, E-mail: prentzepis@ece.tamu.edu [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843 (United States)

2014-09-07

Phonon propagation across the interface of a Cu/Ag(111) bilayer and transient lattice disorder, induced by a femtosecond 267 nm pulse, in Ag(111) crystal have been measured by means of time resolved X-ray diffraction. A “blast” force due to thermal stress induced by suddenly heated electrons is formed within two picoseconds after excitation and its “blast wave” propagation through the interface and Ag (111) crystal was monitored by the shift and broadening of the rocking curve, I vs. ω, as a function of time after excitation. Lattice disorder, contraction and expansion as well as thermal strain formation and wave propagation have also been measured. The experimental data and mechanism proposed are supported by theoretical simulations.

Investigation of the cluster formation in lithium niobate crystals by computer modeling method

Energy Technology Data Exchange (ETDEWEB)

Voskresenskii, V. M.; Starodub, O. R., E-mail: ol-star@mail.ru; Sidorov, N. V.; Palatnikov, M. N. [Russian Academy of Sciences, Tananaev Institute of Chemistry and Technology of Rare Earth Elements and Mineral Raw Materials, Kola Science Centre (Russian Federation)

2017-03-15

The processes occurring upon the formation of energetically equilibrium oxygen-octahedral clusters in the ferroelectric phase of a stoichiometric lithium niobate (LiNbO{sub 3}) crystal have been investigated by the computer modeling method within the semiclassical atomistic model. An energetically favorable cluster size (at which a structure similar to that of a congruent crystal is organized) is shown to exist. A stoichiometric cluster cannot exist because of the electroneutrality loss. The most energetically favorable cluster is that with a Li/Nb ratio of about 0.945, a value close to the lithium-to-niobium ratio for a congruent crystal.

Time resolved X-ray micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectric liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Yumiko; Iida, Atuso E-mail: atsuo.iida@kek.jp; Takanishi, Yoichi; Ogasawara, Toyokazu; Takezoe, Hideo

2001-07-21

The time-resolved synchrotron X-ray microbeam diffraction experiment has been carried out to reveal the local layer response to the electric field in the antiferroelectric liquid crystal. The X-ray microbeam of a few {mu}m spatial resolution was obtained with Kirkpatrick-Baez optics. The time-resolved small angle diffraction experiment was performed with a time resolution ranging from 10 {mu}s to a few ms. The reversible local layer change between the horizontal chevron and the quasi-bookshelf structure was confirmed by the triangular wave form. The transient layer response for the step form electric field was observed. The layer response closely related with an electric field induced antiferroelectric to ferroelectric phase transition.

Time resolved X-ray micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectric liquid crystals

International Nuclear Information System (INIS)

Takahashi, Yumiko; Iida, Atuso; Takanishi, Yoichi; Ogasawara, Toyokazu; Takezoe, Hideo

2001-01-01

The time-resolved synchrotron X-ray microbeam diffraction experiment has been carried out to reveal the local layer response to the electric field in the antiferroelectric liquid crystal. The X-ray microbeam of a few μm spatial resolution was obtained with Kirkpatrick-Baez optics. The time-resolved small angle diffraction experiment was performed with a time resolution ranging from 10 μs to a few ms. The reversible local layer change between the horizontal chevron and the quasi-bookshelf structure was confirmed by the triangular wave form. The transient layer response for the step form electric field was observed. The layer response closely related with an electric field induced antiferroelectric to ferroelectric phase transition

First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments

Directory of Open Access Journals (Sweden)

Maxime Deutsch

2014-05-01

Full Text Available Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed.

First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments.

Science.gov (United States)

Deutsch, Maxime; Gillon, Béatrice; Claiser, Nicolas; Gillet, Jean-Michel; Lecomte, Claude; Souhassou, Mohamed

2014-05-01

Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density) and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT) calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed.

Multiphase Combustion of Metalized Nanocomposite Energetic Materials

Science.gov (United States)

2014-12-19

on thermal conductivity and absorption coefficient for consolidated aluminum nanoparticles, International Journal of Heat and Mass Transfer, (06...28. Stacy, S.C., Zhang, X., Pantoya, M.L., Weeks, B., Effect of Density on Thermal Conductivity and Absorption Coefficient for Consolidated Aluminum...energetic powder to ESD stimuli generated from a piezo electric crystal ( PZT ). Results show that a high PZT dielectric strength leads to faster

Structural energetics of noble metals

International Nuclear Information System (INIS)

Mujibur Rahman, S.M.

1982-06-01

Structural energetics of the noble metals, namely Cu, Ag, and Au are investigated by employing a single-parameter pseudopotential. The calculations show that the lowest energy for all of these metals corresponds to FCC - their observed crystal structure. The one-electron contribution to the free energy is found to dominate the structural prediction for these metals. The present investigation strongly emphasizes that the effects due to band hybridization and core-core exchange play a significant role on the structural stability of the noble metals. (author)

Photoelectron spectroscopy at a free-electron laser. Investigation of space-charge effects in angle-resolved and core-level spectroscopy and realizaton of a time-resolved core-level photoemission experiment

International Nuclear Information System (INIS)

Marczynski-Buehlow, Martin

2012-01-01

intensities using the transition metal dichalcogenides 1T-TiTe 2 and 1T-TaS 2 as reference systems. ARPES at FLASH is in principle feasible below the SCE limit and triangular structured radiation damages (in accordance with the crystal structure) occured only at highest FEL pulse intensities not usable for PES. With increasing photoelectron densities, increasing energetic shifts and broadenings in the range of several eV were observed. Intensity dependent XPS measurements on 1T-TaS 2 could be reproduced by the simulations with the Treecode Algorithm and a linear behavior of the energetic shift and broadening as a function of the electron number was found. Finally, the results of first time.resolved XPS measurements on the Ta 4f core levels of 1T-TaS 2 in the CDW-insulating phase using a - in comparison with HHG sources - high photon energy of ∼175 eV are presented for the first time. A time-dependent evolution of the low binding energy edge of the Ta 4f core levels was observed. This effect could almost certainly be attributed to varying FEL intensities indicating that induced SCEs interfere with possible physical effects. However, with the same setup, our research group repeated the experiment with significantly better temporal resolution and succeeded in measuring directly the charge order dynamics in the complex material 1T-TaS 2 with a temporal resolution of 700 fs and atomic-site sensitivity for the first time.

Photoelectron spectroscopy at a free-electron laser. Investigation of space-charge effects in angle-resolved and core-level spectroscopy and realizaton of a time-resolved core-level photoemission experiment

Energy Technology Data Exchange (ETDEWEB)

Marczynski-Buehlow, Martin

2012-01-30

FEL pulse intensities using the transition metal dichalcogenides 1T-TiTe{sub 2} and 1T-TaS{sub 2} as reference systems. ARPES at FLASH is in principle feasible below the SCE limit and triangular structured radiation damages (in accordance with the crystal structure) occured only at highest FEL pulse intensities not usable for PES. With increasing photoelectron densities, increasing energetic shifts and broadenings in the range of several eV were observed. Intensity dependent XPS measurements on 1T-TaS{sub 2} could be reproduced by the simulations with the Treecode Algorithm and a linear behavior of the energetic shift and broadening as a function of the electron number was found. Finally, the results of first time.resolved XPS measurements on the Ta 4f core levels of 1T-TaS{sub 2} in the CDW-insulating phase using a - in comparison with HHG sources - high photon energy of {approx}175 eV are presented for the first time. A time-dependent evolution of the low binding energy edge of the Ta 4f core levels was observed. This effect could almost certainly be attributed to varying FEL intensities indicating that induced SCEs interfere with possible physical effects. However, with the same setup, our research group repeated the experiment with significantly better temporal resolution and succeeded in measuring directly the charge order dynamics in the complex material 1T-TaS{sub 2} with a temporal resolution of 700 fs and atomic-site sensitivity for the first time.

Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

Directory of Open Access Journals (Sweden)

Klaus Mann

2009-11-01

Full Text Available Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm. The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs. Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.

The energetics and structure of nickel clusters: Size dependence

International Nuclear Information System (INIS)

Cleveland, C.L.; Landman, U.

1991-01-01

The energetics of nickel clusters over a broad size range are explored within the context of the many-body potentials obtained via the embedded atom method. Unconstrained local minimum energy configurations are found for single crystal clusters consisting of various truncations of the cube or octahedron, with and without (110) faces, as well as some monotwinnings of these. We also examine multitwinned structures such as icosahedra and various truncations of the decahedron, such as those of Ino and Marks. These clusters range in size from 142 to over 5000 atoms. As in most such previous studies, such as those on Lennard-Jones systems, we find that icosahedral clusters are favored for the smallest cluster sizes and that Marks' decahedra are favored for intermediate sizes (all our atomic systems larger than about 2300 atoms). Of course very large clusters will be single crystal face-centered-cubic (fcc) polyhedra: the onset of optimally stable single-crystal nickel clusters is estimated to occur at 17 000 atoms. We find, via comparisons to results obtained via atomistic calculations, that simple macroscopic expressions using accurate surface, strain, and twinning energies can usefully predict energy differences between different structures even for clusters of much smaller size than expected. These expressions can be used to assess the relative energetic merits of various structural motifs and their dependence on cluster size

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

Science.gov (United States)

Bromberger, H.; Ermolov, A.; Belli, F.; Liu, H.; Calegari, F.; Chávez-Cervantes, M.; Li, M. T.; Lin, C. T.; Abdolvand, A.; Russell, P. St. J.; Cavalleri, A.; Travers, J. C.; Gierz, I.

2015-08-01

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few μJ energy generate vacuum ultraviolet radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi2Se3 with a signal to noise ratio comparable to that obtained with high order harmonics from a gas jet. The two-order-of-magnitude gain in efficiency promises time-resolved ARPES measurements at repetition rates of hundreds of kHz or even MHz, with photon energies that cover the first Brillouin zone of most materials.

X-ray spectrometer having 12 000 resolving power at 8 keV energy

Science.gov (United States)

Seely, John F.; Hudson, Lawrence T.; Henins, Albert; Feldman, Uri

2017-10-01

An x-ray spectrometer employing a thin (50 μm) silicon transmission crystal was used to record high-resolution Cu Kα spectra from a laboratory x-ray source. The diffraction was from the (331) planes that were at an angle of 13.26° to the crystal surface. The components of the spectral lines resulting from single-vacancy (1s) and double-vacancy (1s and 3d) transitions were observed. After accounting for the natural lifetime widths from reference double-crystal spectra and the spatial resolution of the image plate detector, the intrinsic broadening of the transmission crystal was measured to be as small as 0.67 eV and the resolving power 12 000, the highest resolving power achieved by a compact (0.5 m long) spectrometer employing a single transmission crystal operating in the hard x-ray region. By recording spectra with variable source-to-crystal distances and comparing to the calculated widths from various geometrical broadening mechanisms, the primary contributions to the intrinsic crystal broadening were found to be the source height at small distances and the crystal apertured height at large distances. By reducing these two effects, using a smaller source size and vignetting the crystal height, the intrinsic crystal broadening is then limited by the crystal thickness and the rocking curve width and would be 0.4 eV at 8 keV energy (20 000 resolving power).

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

Energy Technology Data Exchange (ETDEWEB)

Bromberger, H., E-mail: Hubertus.Bromberger@mpsd.mpg.de; Liu, H.; Chávez-Cervantes, M.; Gierz, I. [Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg (Germany); Ermolov, A.; Belli, F.; Abdolvand, A.; Russell, P. St. J.; Travers, J. C. [Max Planck Institute for the Science of Light, Günther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Calegari, F. [Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg (Germany); Institute for Photonics and Nanotechnologies, IFN-CNR, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Li, M. T.; Lin, C. T. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Cavalleri, A. [Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg (Germany); Clarendon Laboratory, Department of Physics, University of Oxford, Parks Rd. Oxford OX1 3PU (United Kingdom)

2015-08-31

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few μJ energy generate vacuum ultraviolet radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi{sub 2}Se{sub 3} with a signal to noise ratio comparable to that obtained with high order harmonics from a gas jet. The two-order-of-magnitude gain in efficiency promises time-resolved ARPES measurements at repetition rates of hundreds of kHz or even MHz, with photon energies that cover the first Brillouin zone of most materials.

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

International Nuclear Information System (INIS)

Bromberger, H.; Liu, H.; Chávez-Cervantes, M.; Gierz, I.; Ermolov, A.; Belli, F.; Abdolvand, A.; Russell, P. St. J.; Travers, J. C.; Calegari, F.; Li, M. T.; Lin, C. T.; Cavalleri, A.

2015-01-01

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few μJ energy generate vacuum ultraviolet radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi 2 Se 3 with a signal to noise ratio comparable to that obtained with high order harmonics from a gas jet. The two-order-of-magnitude gain in efficiency promises time-resolved ARPES measurements at repetition rates of hundreds of kHz or even MHz, with photon energies that cover the first Brillouin zone of most materials

Computational strain gradient crystal plasticity

DEFF Research Database (Denmark)

Niordson, Christian Frithiof; Kysar, Jeffrey W.

2014-01-01

A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

Time-resolved Femtosecond Photon Echo Probes Bimodal Solvent Dynamics

NARCIS (Netherlands)

Pshenichnikov, M.S; Duppen, K.; Wiersma, D. A.

1995-01-01

We report on time-resolved femtosecond photon echo experiments of a dye molecule in a polar solution. The photon echo is time resolved by mixing the echo with a femtosecond gate pulse in a nonlinear crystal. It is shown that the temporal profile of the photon echo allows separation of the

Design parameters of transmission curved crystal spectrometer for hard X-ray diagnoses

International Nuclear Information System (INIS)

Qian Feng; Cao Leifeng; Zhou Weimin; Zhao Zongqing; Gu Yuqiu; Yan Yonghong; Wei Lai; Xiao Shali

2013-01-01

The high resolving measurement of hard X-ray spectra generated in laser-produced plasma is usually performed using a cylindrically curved crystal spectrometer. In this paper, theoretical analysis and numerical simulation are performed to investigate the dependence of the energy range and resolving power on various design parameters, including crystal bending radius, source to crystal standoff distance, source size, location of the detector, etc. The investigation provides a means to design and develop cylindrically transmission curved crystal spectrometer which is used in hard X-ray diagnostics. The results show that crystal bending radius has a great influence on energy range of spectra and resolving power, and the separation between the spectral lines increases with the distance behind the focal circle faster than the line width, resulting in increased resolving power with distance. (authors)

Low temperature time resolved photoluminescence in ordered and disordered Cu{sub 2}ZnSnS{sub 4} single crystals

Energy Technology Data Exchange (ETDEWEB)

Raadik, Taavi, E-mail: taavi.raadik@ttu.ee [Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Krustok, Jüri; Kauk-Kuusik, M.; Timmo, K.; Grossberg, M. [Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Ernits, K. [crystalsol OÜ, Akadeemia tee 15a, 12618 Tallinn (Estonia); Bleuse, J. [CEA-CNRS-UGA group “Nanophysique et Semiconducteurs”, Univ. Grenoble Alpes, INAC-PHELIQS, CEA, INAC-PHELIQS, CNRS, PLUM, F-38000 Grenoble (France)

2017-03-01

In this work we performed time-resolved micro-photoluminescence (TRPL) studies of Cu{sub 2}ZnSnS{sub 4} (CZTS) single crystals grown in molten KI salt. The order/disorder degree of CZTS was varied by the thermal post treatment temperature. Photoluminescence spectra measured at T=8 K showed an asymmetric band with a peak position of 1.33 eV and 1.27 eV for partially ordered and disordered structures, respectively. Thermal activation energies were found to be E{sub T} {sub (PO)} =65±9 meV for partially ordered and E{sub T(PD)} =27±4 meV for partially disordered. These low activation energy values indicating to the defect cluster recombination model for both partially ordered and disordered structures. TRPL was measured for both crystals and their decay curves were fitted with a stretched exponential function, in order to describe the charge carriers’ recombination dynamics at low temperature.

Roles of kinetics and energetics in the growth of AlN by plasma-assisted molecular beam epitaxy

International Nuclear Information System (INIS)

Im, I. H.; Minegishi, T.; Hanada, T.; Lee, S. W.; Cho, M. W.; Yao, T.; Oh, D. C.; Chang, J. H.

2006-01-01

The roles of kinetics and energetics in the growth processes of AlN on c-sapphire by plasma assisted molecular beam epitaxy are investigated by varying the growth rate from 1 to 31 A/min and the substrate temperature from 800 to 1000 .deg. C. The energetics is found to govern the growth of AlN in the low-growth rate region even at a low substrate temperature of 800 .deg. C owing to the enhanced residence time of adatoms, thereby increasing the surface migration length. As the growth rate increases, the growth tends to be governed by kinetics because of a reduction in the residence time of adatoms. Consequently, the surface roughness and crystal quality are greatly improved for the low-growth-rate case. In addition, the lattice strain relaxation is completed from the beginning of epitaxy for energetics-limiting growth while lattice strain relaxation is retarded for kinetics-limiting growth because of pre-existing partial strain relaxation. Energetics becomes more favorable as the substrate temperature is raised because of an increase in the surface diffusion length owing to an enhanced diffusion coefficient. Consequently high-crystal-quality AlN layers are grown under the energetics-limiting growth condition with a screw dislocation density of 7.4 x 10 8 cm -2 even for a thin 42-nm thick film.

Atomic structures and mechanical properties of single-crystal GaN nanotubes

International Nuclear Information System (INIS)

Xu, B.; Lu, A.J.; Pan, B.C.; Yu, Q.X.

2005-01-01

An approach is proposed to theoretically construct a realistic single-crystal GaN nanotube at atomic scale. The generated atomic structures of the single-crystal GaN nanotubes match the structural aspects from experiment very well. Our energetic calculations show that a single-crystal GaN nanotube with [100]-oriented lateral facets is more stable than that with [110]-oriented lateral facets, when they have around the same wall thickness. For a specified orientation of the lateral facets on the single-crystal GaN nanotubes, the energetic stabilities of the tubes obey a P rule, in which P is the ratio of the number of four-coordinated atoms to the number of three-coordinated atoms. Furthermore, the Young's modulus of the considered GaN nanotubes decrease with increasing the ratio of the number of bulk atoms to the number of surface atoms in each type of tube. Our calculations and analysis demonstrate that the surface effect of a single-crystal nanotube enhances its Young's modulus significantly

Energetic band structure of Zn3P2 crystals

Science.gov (United States)

Stamov, I. G.; Syrbu, N. N.; Dorogan, A. V.

2013-01-01

Optical functions n, k, ε1, ε2 and d2ε2/dE2 have been determined from experimental reflection spectra in the region of 1-10 eV. The revealed electronic transitions are localized in the Brillouin zone. The magnitude of valence band splitting caused by the spin-orbital interaction ΔSO is lower than the splitting caused by the crystal field ΔCR in the center of Brillouin zone and L and X points. The switching effects are investigated in Zn3P2 crystals. The characteristics of experimental samples with electric switching, adjustable resistors, and time relays based on Zn3P2 are presented.

Nanostructured energetic materials derived from sol-gel chemistry

International Nuclear Information System (INIS)

Simpson, R L; Tillotson, T M; Hrubesh, L W; Gash, A E

2000-01-01

Initiation and detonation properties are dramatically affected by an energetic material's microstructural properties. Sol-gel chemistry allows intimacy of mixing to be controlled and dramatically improved over existing methodologies. One material goal is to create very high power energetic materials which also have high energy densities. Using sol-gel chemistry we have made a nanostructured composite energetic material. Here a solid skeleton of fuel, based on resorcinol-formaldehyde, has nanocrystalline ammonium perchlorate, the oxidizer, trapped within its pores. At optimum stoichiometry it has approximately the energy density of HMX. Transmission electron microscopy indicated no ammonium perchlorate crystallites larger than 20 nm while near-edge soft x-ray absorption microscopy showed that nitrogen was uniformly distributed, at least on the scale of less than 80 nm. Small-angle neutron scattering studies were conducted on the material. Those results were consistent with historical ones for this class of nanostructured materials. The average skeletal primary particle size was on the order of 2.7 nm, while the nanocomposite showed the growth of small 1 nm size crystals of ammonium perchlorate with some clustering to form particles greater than 10 nm

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

OpenAIRE

Bromberger, H.; Ermolov, A.; Belli, F.; Liu, H.; Calegari, F.; Chavez-Cervantes, M.; Li, M. T.; Lin, C. T.; Abdolvand, A.; Russell, P. St. J.; Cavalleri, A.; Travers, J. C.; Gierz, I.

2015-01-01

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few {\\mu}J energy generate vacuum ultraviolet (VUV) radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi2Se3 with a signal to noise ratio comparable to ...

Structural evolution in the isothermal crystallization process of the molten nylon 10/10 traced by time-resolved infrared spectral measurements and synchrotron SAXS/WAXD measurements

International Nuclear Information System (INIS)

Tashiro, Kohji; Nishiyama, Asami; Tsuji, Sawako; Hashida, Tomoko; Hanesaka, Makoto; Takeda, Shinichi; Weiyu, Cao; Reddy, Kummetha Raghunatha; Masunaga, Hiroyasu; Sasaki, Sono; Takata, Masaki; Ito, Kazuki

2009-01-01

The structural evolution in the isothermal crystallization process of nylon 10/10 from the melt has been clarified concretely on the basis of the time-resolved infrared spectral measurement as well as the synchrotron wide-angle and small-angle X-ray scattering measurements. Immediately after the temperature jump from the melt to the crystallization point, the isolated domains consisting of the hydrogen-bonded random coils were formed in the melt, as revealed by Guinier plot of SAXS data and the infrared spectral data. With the passage of time these domains approached each other with stronger correlation as analyzed by Debye-Bueche equation. These domains transformed finally to the stacked crystalline lamellae, in which the conformationally-regularized methylene segments of the CO sides were connected each other by stronger intermolecular hydrogen bonds to form the crystal lattice.

Crystal morphology variation in inkjet-printed organic materials

Science.gov (United States)

Ihnen, Andrew C.; Petrock, Anne M.; Chou, Tsengming; Samuels, Phillip J.; Fuchs, Brian E.; Lee, Woo Y.

2011-11-01

The recent commercialization of piezoelectric-based drop-on-demand inkjet printers provides an additive processing platform for producing and micropatterning organic crystal structures. We report an inkjet printing approach where macro- and nano-scale energetic composites composed of cyclotrimethylenetrinitramine (RDX) crystals dispersed in a cellulose acetate butyrate (CAB) matrix are produced by direct phase transformation from organic solvent-based all-liquid inks. The characterization of printed composites illustrates distinct morphological changes dependent on ink deposition parameters. When 10 pL ink droplets rapidly formed a liquid pool, a coffee ring structure containing dendritic RDX crystals was produced. By increasing the substrate temperature, and consequently the evaporation rate of the pooled ink, the coffee ring structure was mitigated and shorter dendrites from up to ∼1 to 0.2 mm with closer arm spacing from ∼15 to 1 μm were produced. When the nucleation and growth of RDX and CAB were confined within the evaporating droplets, a granular structure containing nanoscale RDX crystals was produced. The results suggest that evaporation rate and microfluidic droplet confinement can effectively be used to tailor the morphology of inkjet-printed energetic composites.

Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

Energy Technology Data Exchange (ETDEWEB)

Kuehnel, Matthias

2014-02-15

This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are

Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

International Nuclear Information System (INIS)

Kuehnel, Matthias

2014-02-01

This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are

Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

Energy Technology Data Exchange (ETDEWEB)

Kuehnel, Matthias

2014-02-15

This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are

Study of the Bulk Charge Carrier Dynamics in Anatase and Rutile TiO2 Single Crystals by Femtosecond Time Resolved Spectroscopy

KAUST Repository

Maity, Partha

2018-04-02

Understanding of the fundamentals behind charge carriers of photo-catalytic materials are still illusive hindering progress in our quest for renewable energy. TiO2 anatase and rutile are the most understood phases in photo-catalysis and serve as the best model for fundamental studies. Their ultrafast charge carrier dynamics especially on TiO2 anatase single crystal (the most active phase) are unresolved. Here femtosecond time resolved spectroscopy (TRS) was carried out to explore the dynamics of photo-excited charge carriers’ recombination in anatase single crystal, for the first time using pump fluence effects, and compares it to that of the rutile single crystal. A significant difference in charge carrier recombination rates between both crystals is observed. We found that the time constants for carrier recombination are two orders of magnitude slower for anatase (101) when compared to those of rutile (110). Moreover, bulk defects introduced by reduction of the samples via annealing in ultra-high vacuum resulted in faster recombination rates for both polymorphs. Both states (fresh and reduced) probed by pump fluence dependence measurements revealed that the major recombination channel in fresh and reduced anatase and reduced rutile is the first-order Shockley–Reed mediated. However, for fresh rutile, third-body Auger recombination was observed, attributed to the presence of higher density of intrinsic charge carriers. At all excitation wavelengths and fluence investigated, anatase (101) single crystal show longer charge carrier lifetime when compared to rutile (110) single. This may explain the superiority of the anatase phase for the electron transfer H+ reduction to molecular hydrogen.

Surface Thermometry of Energetic Materials by Laser-Induced Fluorescence

Science.gov (United States)

1989-09-01

at 34 yttrium- aluminum -garnet (Dy:YAG). The simplified energy diagram of Dy:YAG is shown in Fig. 1. Absorbed laser light (at 355 nrm) can 5 excite the...the thermometric technique on a surface similar to that of an energetic material, a thermal-setting plastic supplied by Buehler, Ltd., was employed...temperature over the temperature range of interest. The rare-earth ion dysprosium (Dy) doped into a yttrium- aluminum -garnet (YAG) crystal was I determined

Molecular Weight and Crystallization Temperature Effects on Poly(ethylene terephthalate (PET Homopolymers, an Isothermal Crystallization Analysis

Directory of Open Access Journals (Sweden)

Leonardo A. Baldenegro-Perez

2014-02-01

Full Text Available The isothermal crystallization of poly(ethylene terephthalate (PET homopolymers with different molecular weight was studied in a wide temperature range (140–230 °C using different experimental techniques. Three different morphological regions, labeled r1, r2 and r3, were distinguished as a function of crystallization temperature (Tc. In r1 (low Tc crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals. In r2 (intermediate Tc samples showed medium size spherulites composed of two distinct crystalline families (thin and thick crystals. In this temperature range, the crystallization exhibited a maximum value and it was associated with a high content of secondary crystals. In r3 (high Tc, samples presented considerable amorphous zones and regions consisting of oversized spherulites containing only thick crystals. Time-resolved wide-angle X-ray diffraction measurements, using synchrotron radiation, indicated a rapid evolution of the crystalline degree within the second region, in contrast with the quite slow evolution observed in the third region. On the other hand, by small-angle X-ray scattering (SAXS and time-resolved SAXS experiment, it was found that the long period (L as well as the lamellar thickness (lc increase as a function of Tc, corroborating the formation of the thickest crystals in the third region. From all these observations, a morphological model was proposed for each region.

Energetic Systems

Data.gov (United States)

Federal Laboratory Consortium — The Energetic Systems Division provides full-spectrum energetic engineering services (project management, design, analysis, production support, in-service support,...

Dynamics of Spontaneous Emission Controlled by Local Density of States in Photonic Crystals

DEFF Research Database (Denmark)

Lodahl, Peter; Nikolaev, Ivan S.; van Driel, A. Floris

2006-01-01

We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter.......We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter....

Inulin isoforms differ by repeated additions of one crystal unit cell

Science.gov (United States)

Cooper, Peter D.; Barclay, Thomas G.; Ginic-Markovic, Milena; Gerson, Andrea R.; Petrovsky, Nikolai

2014-01-01

Inulin isoforms, especially delta inulin, are important biologically as immune activators and clinically as vaccine adjuvants. In exploring action mechanisms, we previously found regular increments in thermal properties of the seven-member inulin isoform series that suggested regular additions of some energetic structural unit. Because the previous isolates carried additional longer chains that masked defining ranges, these were contrasted with new isoform isolates comprising only inulin chain lengths defining that isoform. The new series began with 19 fructose units per chain (alpha-1 inulin), increasing regularly by 6 fructose units per isoform. Thus the ‘energetic unit’ equates to 6 fructose residues per chain. All isoforms showed indistinguishable X-ray diffraction patterns that were also identical with known inulin crystals. We conclude that an ‘energetic unit’ equates to one helix turn of 6 fructose units per chain as found in one unit cell of the inulin crystal. Each isoform chain comprised progressively more helix turns plus one additional fructose and glucose residues per chain. PMID:24528745

Time Resolved Deposition Measurements in NSTX

International Nuclear Information System (INIS)

Skinner, C.H.; Kugel, H.; Roquemore, A.L.; Hogan, J.; Wampler, W.R.

2004-01-01

Time-resolved measurements of deposition in current tokamaks are crucial to gain a predictive understanding of deposition with a view to mitigating tritium retention and deposition on diagnostic mirrors expected in next-step devices. Two quartz crystal microbalances have been installed on NSTX at a location 0.77m outside the last closed flux surface. This configuration mimics a typical diagnostic window or mirror. The deposits were analyzed ex-situ and found to be dominantly carbon, oxygen, and deuterium. A rear facing quartz crystal recorded deposition of lower sticking probability molecules at 10% of the rate of the front facing one. Time resolved measurements over a 4-week period with 497 discharges, recorded 29.2 (micro)g/cm 2 of deposition, however surprisingly, 15.9 (micro)g/cm 2 of material loss occurred at 7 discharges. The net deposited mass of 13.3 (micro)g/cm 2 matched the mass of 13.5 (micro)g/cm 2 measured independently by ion beam analysis. Monte Carlo modeling suggests that transient processes are likely to dominate the deposition

Bipolarons in nonmetallic crystals

International Nuclear Information System (INIS)

Vinetskii, V.L.; Pashitskii, E.A.; Yanchuk, V.A.

1987-01-01

The binding energy of a bipolaron in an ionic crystal increases substantially in the case of strong anisotropy of the effective masses of the free carriers of the easy plane type or easy axis type. In the second case the polaron is cigar-like in shape and the coaxial configuration of bipolarons is energetically favorable. In this case a significant gain in the binding energy and in the width of the region of existence of the bipolaron, with respect to the dielectric constant and the magnitude of the electron-phonon interaction constant, compared with an isotropic crystal, is obtained only for quasi-two-dimensional, or layered, and quasi-one-dimensional, or chainlike, crystals. This work shows that a significant gain in the binding energy can be obtained by taking into account the anisotropy of the dielectric constant of the crystal and localization of the electron wave functions in directions perpendicular to the layers and chains of atoms

Time-resolved protein nano-crystallography using an X-ray free-electron laser

International Nuclear Information System (INIS)

Aquila, Andrew; Hunter, Mark S.; Fromme, Petra; Fromme, Raimund; Grotjohann, Ingo; Doak, R. Bruce; Kirian, Richard A.; Schmidt, Kevin E.; Wang, Xiaoyu; Weierstall, Uwe; Spence, John C.H.; White, Thomas A.; Caleman, Carl; DePonte, Daniel P.; Fleckenstein, Holger; Gumprecht, Lars; Liang, Mengning; Martin, Andrew V.; Schulz, Joachim; Stellato, Francesco; Stern, Stephan; Barty, Anton; Andreasson, Jakob; Davidsson, Jan; Hajdu, Janos; Maia, Filipe R.N.C.; Seibert, M. Marvin; Timneanu, Nicusor; Arnlund, David; Johansson, Linda; Malmerberg, Erik; Neutze, Richard; Bajt, Sasa; Barthelmess, Miriam; Graafsma, Heinz; Hirsemann, Helmut; Wunderer, Cornelia; Barends, Thomas R.M.; Foucar, Lutz; Krasniqi, Faton; Lomb, Lukas; Rolles, Daniel; Schlichting, Ilme; Schmidt, Carlo; Bogan, Michael J.; Hampton, Christina Y.; Sierra, Raymond; Starodub, Dmitri; Bostedt, Christoph; Bozek, John D.; Messerschmidt, Marc; Williams, Garth J.; Bottin, Herve

2012-01-01

We demonstrate the use of an X-ray free electron laser synchronized with an optical pump laser to obtain X-ray diffraction snapshots from the photo-activated states of large membrane protein complexes in the form of nano-crystals flowing in a liquid jet. Light-induced changes of Photosystem I-Ferredoxin co-crystals were observed at time delays of 5 to 10 μs after excitation. The result correlates with the microsecond kinetics of electron transfer from Photosystem I to ferredoxin. The undocking process that follows the electron transfer leads to large rearrangements in the crystals that will terminally lead to the disintegration of the crystals. We describe the experimental setup and obtain the first time resolved femtosecond serial X-ray crystallography results from an irreversible photo-chemical reaction at the Linac Coherent Light Source. This technique opens the door to time-resolved structural studies of reaction dynamics in biological systems. (authors)

Energetic dislocation interactions and thermodynamical aspects of strain gradient crystal plasticity theories

NARCIS (Netherlands)

Ertürk, I.; Dommelen, van J.A.W.; Geers, M.G.D.

2009-01-01

This paper focuses on the unification of two frequently used and apparently different strain gradient crystal plasticity frameworks: (i) the physicallymotivated strain gradient crystal plasticity models proposed by Evers et al. (2004a,b) and Bayley et al. (2006, 2007) (here referred to as

Screening in crystalline liquids protects energetic carriers in hybrid perovskites

Science.gov (United States)

Zhu, Haiming; Miyata, Kiyoshi; Fu, Yongping; Wang, Jue; Joshi, Prakriti; Niesner, Daniel; Williams, Kristopher; Jin, Song; Zhu, Xiaoyang

Hybrid lead halide perovskites exhibit carrier properties that resemble those of pristine nonpolar semiconductors despite static and dynamic disorder, but how carriers are protected from efficient scattering with charged defects and optical phonons is unknown. Here, we reveal the carrier protection mechanism by comparing three single-crystal lead bromide perovskites: CH3NH3PbBr3, CH(NH2)2PbBr3, and CsPbBr3. We observed hot fluorescence emission from energetic carriers with 102 picosecond lifetimes in CH3NH3PbBr3 or CH(NH,SUB>2)2PbBr3, but not in CsPbBr3. The hot fluorescence is correlated with liquid-like molecular reorientational motions, suggesting that dynamic screening protects energetic carriers via solvation or large polaron formation on time scales competitive with that of ultrafast cooling. Similar protections likely exist for band-edge carriers. The long-lived energetic carriers may enable hot-carrier solar cells with efficiencies exceeding the Shockley-Queisser limit. This work was supported by U.S. Department of Energy Grant ER46980, National Science Foundation, Grant DMR 1420634 (MRSEC), and Department of Energy Award DE-FG02-09ER46664.

Trapping crystal nucleation of cholesterol monohydrate

DEFF Research Database (Denmark)

Solomonov, I.; Weygand, M.J.; Kjær, K.

2005-01-01

Crystalline nucleation of cholesterol at the air-water interface has been studied via grazing incidence x-ray diffraction using synchrotron radiation. The various stages of cholesterol molecular assembly from monolayer to three bilayers incorporating interleaving hydrogen-bonded water layers......, at least initially, an intralayer cholesterol rearrangement in a single-crystal-to-single-crystal transition. The preferred nucleation of the monoclinic phase of cholesterol . H2O followed by transformation to the stable monohydrate phase may be associated with an energetically more stable cholesterol...... bilayer arrangement of the former and a more favorable hydrogen-bonding arrangement of the latter. The relevance of this nucleation process of cholesterol monohydrate to pathological crystallization of cholesterol from cell biomembranes is discussed....

Spatially-resolved measurement of optically stimulated luminescence and time-resolved luminescence

International Nuclear Information System (INIS)

Bailiff, I.K.; Mikhailik, V.B.

2003-01-01

Spatially-resolved measurements of optically stimulated luminescence (OSL) were performed using a two-dimensional scanning system designed for use with planar samples. The scanning system employs a focused laser beam to stimulate a selected area of the sample, which is moved under the beam by a motorised stage. Exposure of the sample is controlled by an electronic shutter. Mapping of the distribution of OSL using a continuous wave laser source was obtained with sub-millimeter resolution for samples of sliced brick, synthetic single crystal quartz, concrete and dental ceramic. These revealed sporadic emission in the case of brick or concrete and significant spatial variation of emission for quartz and dental ceramic slices. Determinations of absorbed dose were performed for quartz grains within a slice of modern brick. Reconfiguration of the scanner with a pulsed laser source enabled quartz and feldspathic minerals within a ceramic sample to be thinner region. about 6 nm from the extrapolation of themeasuring the time-resolved luminescence spectrum

Effect of Defects on Mechanisms of Initiation and Energy Release in Energetic Molecular Crystals

Science.gov (United States)

2011-02-10

also examined other energetic and reactive materials such as 1,3,5,7 cyclooctatetraene (COT) and potassium chlorate (KClO3) and ringed hydrocarbons...the space charge induced by the diffusive separation of potassium and fluoride ions in the shock wave affects polarization currents and depends on

Anomalous maximum and minimum for the dissociation of a geminate pair in energetically disordered media

Science.gov (United States)

Govatski, J. A.; da Luz, M. G. E.; Koehler, M.

2015-01-01

We study the geminated pair dissociation probability φ as function of applied electric field and temperature in energetically disordered nD media. Regardless nD, for certain parameters regions φ versus the disorder degree (σ) displays anomalous minimum (maximum) at low (moderate) fields. This behavior is compatible with a transport energy which reaches a maximum and then decreases to negative values as σ increases. Our results explain the temperature dependence of the persistent photoconductivity in C60 single crystals going through order-disorder transitions. They also indicate how an energetic disorder spatial variation may contribute to higher exciton dissociation in multicomponent donor/acceptor systems.

Mapping the nanoscale energetic landscape in conductive polymer films with spatially super-resolved exciton dynamics

Science.gov (United States)

Ginsberg, Naomi

2015-03-01

The migration of Frenkel excitons, tightly-bound electron-hole pairs, in polymeric organic semiconducting films is critical to the efficiency of bulk heterojunction solar cells. While these materials exhibit a high degree of structural heterogeneity on the nanoscale, traditional measurements of exciton diffusion lengths are performed on bulk samples. Since both the characteristic length scales of structural heterogeneity and the reported bulk diffusion lengths are smaller than the optical diffraction limit, we adapt far-field super-resolution fluorescence imaging to uncover the correlations between the structural and energetic landscapes that the excitons explore.

Contribution to time resolved X-ray fluence and differential spectra measurement method improvement in 5-200 KeV range. Application to pulsed emission sources

International Nuclear Information System (INIS)

Vie, M.

1983-09-01

Two types of sensors have been developed to measure locally the time-resolved fluence and differential energetic spectrum of pulsed X-ray in the energy range 5 to 200 keV. Rise time of these sensors is very short (10 ns) in order to permit time-resolved measurements. Fluence sensors have been developed by putting filters in front of detector in order to make sensor response independent of X-ray energy and proportional to X-ray fluence. The energetic differential spectrum was calculated by way of a method similar to the ROSS method but using filters separated within a pair defining adjacent spectral width. A detailed analysis of uncertainties affecting calculated fluence and spectrum has been done [fr

Large-Scale Reactive Atomistic Simulation of Shock-induced Initiation Processes in Energetic Materials

Science.gov (United States)

Thompson, Aidan

2013-06-01

Initiation in energetic materials is fundamentally dependent on the interaction between a host of complex chemical and mechanical processes, occurring on scales ranging from intramolecular vibrations through molecular crystal plasticity up to hydrodynamic phenomena at the mesoscale. A variety of methods (e.g. quantum electronic structure methods (QM), non-reactive classical molecular dynamics (MD), mesoscopic continuum mechanics) exist to study processes occurring on each of these scales in isolation, but cannot describe how these processes interact with each other. In contrast, the ReaxFF reactive force field, implemented in the LAMMPS parallel MD code, allows us to routinely perform multimillion-atom reactive MD simulations of shock-induced initiation in a variety of energetic materials. This is done either by explicitly driving a shock-wave through the structure (NEMD) or by imposing thermodynamic constraints on the collective dynamics of the simulation cell e.g. using the Multiscale Shock Technique (MSST). These MD simulations allow us to directly observe how energy is transferred from the shockwave into other processes, including intramolecular vibrational modes, plastic deformation of the crystal, and hydrodynamic jetting at interfaces. These processes in turn cause thermal excitation of chemical bonds leading to initial chemical reactions, and ultimately to exothermic formation of product species. Results will be presented on the application of this approach to several important energetic materials, including pentaerythritol tetranitrate (PETN) and ammonium nitrate/fuel oil (ANFO). In both cases, we validate the ReaxFF parameterizations against QM and experimental data. For PETN, we observe initiation occurring via different chemical pathways, depending on the shock direction. For PETN containing spherical voids, we observe enhanced sensitivity due to jetting, void collapse, and hotspot formation, with sensitivity increasing with void size. For ANFO, we

Energetic materials and methods of tailoring electrostatic discharge sensitivity of energetic materials

Energy Technology Data Exchange (ETDEWEB)

Daniels, Michael A.; Heaps, Ronald J.; Wallace, Ronald S.; Pantoya, Michelle L.; Collins, Eric S.

2016-11-01

An energetic material comprising an elemental fuel, an oxidizer or other element, and a carbon nanofiller or carbon fiber rods, where the carbon nanofiller or carbon fiber rods are substantially homogeneously dispersed in the energetic material. Methods of tailoring the electrostatic discharge sensitivity of an energetic material are also disclosed.

Time-Resolved WAXD and SAXS Investigations on Butyl Branched Alkane at Elevated Pressures

NARCIS (Netherlands)

Rastogi, A.; Hobbs, J.K.; Rastogi, S.

2002-01-01

The crystallization behavior and the morphological aspect of the butyl branched alkane C96H193CH(C4H9)C94H189 have been investigated using time-resolved wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) at atmospheric and elevated pressures. The solution crystallized sample

The Modeling of Coupled Electromagnetic-Thermo-Mechanical Laser Interactions and Microstructural Behavior of Energetic Aggregates

Science.gov (United States)

2015-01-01

analytical Beer - Lambert absorption profile to model laser heating of pure energetic crystals without considering any EM wave propagation effects...temperature. These aggregates were studied using both an analytical distribution for laser heating following Beer - Lambert absorption and the full EM finite...surface (ysurface - y) and material absorption coefficient, α, following a Beer - Lambert absorption relation given by , = !()

Experimental Investigation of the Role of Defects in Detonation Sensitivity of Energetic Materials: Development of Techniques for Characterization

Science.gov (United States)

2009-12-31

materials. The initial work was focused on design and construction of an apparatus for injecting defects into the crystals using PZT ceramics ...in the energy partitioning (Table 2), which offers some insight into the nature of the energetic texture of crystalline materials not apparent in

Energetics Conditioning Facility

Data.gov (United States)

Federal Laboratory Consortium — The Energetics Conditioning Facility is used for long term and short term aging studies of energetic materials. The facility has 10 conditioning chambers of which 2...

Time-resolved x-ray line diagnostics of laser-produced plasmas

International Nuclear Information System (INIS)

Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D.; Lee, R.W.

1982-11-01

We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 μm light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers, whose Z's range from 13 to 22, are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasms is changed from SiO 2 to PbO or In. Spectra will be presented along with preliminary analysis of the data

Time-resolved x-ray line diagnostics of laser-produced plasmas

International Nuclear Information System (INIS)

Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D.; Lee, R.W.

1982-01-01

We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 μm light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers whose Z's range from 13 to 22 are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasma is changed from SiO 2 to PbO or In. Spectra will be presented along with preliminary analysis of the data

Synthesis, crystal structure and catalytic effect on thermal decomposition of RDX and AP: An energetic coordination polymer [Pb{sub 2}(C{sub 5}H{sub 3}N{sub 5}O{sub 5}){sub 2}(NMP)·NMP]{sub n}

Energy Technology Data Exchange (ETDEWEB)

Liu, Jin-jian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yancheng Teachers College, Yancheng 224002 (China); Liu, Zu-Liang, E-mail: liuzl@mail.njust.edu.cn [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Cheng, Jian [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yancheng Teachers College, Yancheng 224002 (China); Fang, Dong, E-mail: fangdong106@163.com [Yancheng Teachers College, Yancheng 224002 (China)

2013-04-15

An energetic lead(II) coordination polymer based on the ligand ANPyO has been synthesized and its crystal structure has been got. The polymer was characterized by FT-IR spectroscopy, elemental analysis, DSC and TG-DTG technologies. Thermal analysis shows that there are one endothermic process and two exothermic decomposition stages in the temperature range of 50–600 °C with final residues 57.09%. The non-isothermal kinetic has also been studied on the main exothermic decomposition using the Kissinger's and Ozawa–Doyle's methods, the apparent activation energy is calculated as 195.2 KJ/mol. Furthermore, DSC measurements show that the polymer has significant catalytic effect on the thermal decomposition of ammonium perchlorate. - Graphical abstract: An energetic lead(II) coordination polymer of ANPyO has been synthesized, structurally characterized and properties tested. Highlights: ► We have synthesized and characterized an energetic lead(II) coordination polymer. ► We have measured its molecular structure and thermal decomposition. ► It has significant catalytic effect on thermal decomposition of AP.

Chemistry and structure of giant molecular clouds in energetic environments

Science.gov (United States)

Anderson, Crystal Nicole

2016-09-01

Throughout the years many studies on Galactic star formation have been conducted. This resulted in the idea that giant molecular clouds (GMCs) are hierarchical in nature with substructures spanning a large range of sizes. The physical processes that determine how molecular clouds fragment, form clumps/cores and then stars depends strongly on both recent radiative and mechanical feed- back from massive stars and, on longer term, from enhanced cooling due to the buildup of metals. Radiative and mechanical energy input from stellar populations can alter subsequent star formation over a large part of a galaxy and hence is relevant to the evolution of galaxies. Much of our knowledge of star formation on galaxy wide scales is based on scaling laws and other parametric descriptions. But to understand the overall evolution of star formation in galaxies we need to watch the feedback processes at work on giant molecular cloud (GMC) scales. By doing this we can begin to answer how strong feedback environments change the properties of the substructure in GMCs. Tests of Galactic star formation theory to other galaxies has been a challenging process due to the lack of resolution with current instruments. Thus, only the nearest galaxies allow us to resolve GMCs and their substructures. The Large Magellanic Cloud (LMC), is one of the closest low metallicity dwarf galaxies (D˜ 50 kpc) and is close enough that current instruments can resolve the sub- structure of its GMCs to molecular gas tracers (e.g. HCO+, HCN, HNC, CS, C2H, N2H+) detected in the LMC at 1.5-40 pc scales and in NGC 5253 at 40 pc scales. I then compare the molecular gas detections to the Central Molecular Zone in our Galaxy. Dense molecular gas was detected in all of the sources. For the regions in the LMC, molecular lines of CS, N2H+, C 2H, HNC, HCO+ and HCN were all detected in N159W and N113 while only HCN, HCO+, HNC, and C2H were detected in 30Dor-10. Toward NGC 5253 only HCO+, HCN, C2H and CS were detected. I

Phenomenon of ''self-cleaning'' of crystals

International Nuclear Information System (INIS)

Matveev, O.A.; Arkad'eva, E.N.; Goncharov, L.A.

1975-01-01

Crystals of germanium and cadmium telluride have been produced having the characteristics corresponding to the low content of electrically active impurities and crystal defects. The crystals have been grown under conditions of an equilibrium diffusion-concentration interaction of the impurities and crystal defects, with the donor alloying and controlling the acceptors concentration. These crystals have been studied with the help of the mass-spectral analysis, the Hall effect, photoelectroscopy, spectral photoconductivity and losses of collection of a charge from an ionizing particle on gamma-detectors fabricated of the crystals. Herein the doped composition of the crystals has been determined, the concentrations of the shallow and deep acceptors and donors have been measured separately, the life-times of the electrons and holes have been measured, the energetic position and the concentration of the carrier capture levels have been determined. The crystals grown possess all the characteristic features of rather pure crystals. The results of the mass-spectral analysis have shown that in the cadmium telluride crystals the impurities are present within 10 14 to 10 17 cm -3 . Therefore, a deep ''self-refining'' of the crystal takes place, which proceeds by means of deactivation of the electrically active centers with their associating into electrically inactive complexes. Thus a fact of the deep ''self-refining'' of germanium- and cadmium telluride crystals is stated. It is presumed that such a ''self-refining'' can actually proceed practically in all the crystals

Gamma induced atom displacements in LYSO and LuYAP crystals as used in medical imaging applications

Energy Technology Data Exchange (ETDEWEB)

Piñera, Ibrahin, E-mail: ipinera@ceaden.edu.cu [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, CEADEN, 30 St. 502, Playa 11300, Havana (Cuba); Cruz, Carlos M.; Abreu, Yamiel; Leyva, Antonio [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, CEADEN, 30 St. 502, Playa 11300, Havana (Cuba); Van Espen, Piet [University of Antwerp, CGB, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Díaz, Angelina; Cabal, Ana E. [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, CEADEN, 30 St. 502, Playa 11300, Havana (Cuba); Van Remortel, Nick [University of Antwerp, CGB, Groenenborgerlaan 171, 2020 Antwerpen (Belgium)

2015-08-01

The radiation damage, in terms of atom displacements, induced by gamma irradiation in LYSO and LuYAP crystals is presented. {sup 44}Sc, {sup 22}Na and {sup 48}V are used as gamma sources for this study. The energy of gammas from the electron–positron annihilation processes (511 keV) is also included in the study. The atom displacements distributions inside each material are calculated following the Monte Carlo assisted Classical Method introduced by the authors. This procedure also allows to study the atom displacements in-depth distributions inside each crystal. The atom displacements damage in LYSO crystals is found to be higher than in LuYAP crystals, mainly provoked by the displacements of silicon and oxygen atoms. But the difference between atom displacements produced in LYSO and LuYAP decreases when more energetic sources are used. On the other hand, the correlation between the atom displacements and energy deposition in-depth distributions is excellent. The atom displacements to energy deposition ratio is found to increases with more energetic photon sources. LYSO crystals are then more liable to the atom displacements damage than LuYAP crystals.

Spatially resolved analysis of short-range structure perturbations in a plastically bent molecular crystal

Science.gov (United States)

Panda, Manas K.; Ghosh, Soumyajit; Yasuda, Nobuhiro; Moriwaki, Taro; Mukherjee, Goutam Dev; Reddy, C. Malla; Naumov, Panče

2015-01-01

The exceptional mechanical flexibility observed with certain organic crystals defies the common perception of single crystals as brittle objects. Here, we describe the morphostructural consequences of plastic deformation in crystals of hexachlorobenzene that can be bent mechanically at multiple locations to 360° with retention of macroscopic integrity. This extraordinary plasticity proceeds by segregation of the bent section into flexible layers that slide on top of each other, thereby generating domains with slightly different lattice orientations. Microscopic, spectroscopic and diffraction analyses of the bent crystal showed that the preservation of crystal integrity when stress is applied on the (001) face requires sliding of layers by breaking and re-formation of halogen-halogen interactions. Application of stress on the (100) face, in the direction where π···π interactions dominate the packing, leads to immediate crystal disintegration. Within a broader perspective, this study highlights the yet unrecognized extraordinary malleability of molecular crystals with strongly anisotropic supramolecular interactions.

Formulation and Testing of Paraffin-Based Solid Fuels Containing Energetic Additives for Hybrid Rockets

Science.gov (United States)

Larson, Daniel B.; Boyer, Eric; Wachs,Trevor; Kuo, Kenneth K.; Story, George

2012-01-01

Many approaches have been considered in an effort to improve the regression rate of solid fuels for hybrid rocket applications. One promising method is to use a fuel with a fast burning rate such as paraffin wax; however, additional performance increases to the fuel regression rate are necessary to make the fuel a viable candidate to replace current launch propulsion systems. The addition of energetic and/or nano-sized particles is one way to increase mass-burning rates of the solid fuels and increase the overall performance of the hybrid rocket motor.1,2 Several paraffin-based fuel grains with various energetic additives (e.g., lithium aluminum hydride (LiAlH4) have been cast in an attempt to improve regression rates. There are two major advantages to introducing LiAlH4 additive into the solid fuel matrix: 1) the increased characteristic velocity, 2) decreased dependency of Isp on oxidizer-to-fuel ratio. The testing and characterization of these solid-fuel grains have shown that continued work is necessary to eliminate unburned/unreacted fuel in downstream sections of the test apparatus.3 Changes to the fuel matrix include higher melting point wax and smaller energetic additive particles. The reduction in particle size through various methods can result in more homogeneous grain structure. The higher melting point wax can serve to reduce the melt-layer thickness, allowing the LiAlH4 particles to react closer to the burning surface, thus increasing the heat feedback rate and fuel regression rate. In addition to the formulation of LiAlH4 and paraffin wax solid-fuel grains, liquid additives of triethylaluminum and diisobutylaluminum hydride will be included in this study. Another promising fuel formulation consideration is to incorporate a small percentage of RDX as an additive to paraffin. A novel casting technique will be used by dissolving RDX in a solvent to crystallize the energetic additive. After dissolving the RDX in a solvent chosen for its compatibility

Absence of Quantum Time Crystals.

Science.gov (United States)

Watanabe, Haruki; Oshikawa, Masaki

2015-06-26

In analogy with crystalline solids around us, Wilczek recently proposed the idea of "time crystals" as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state or in the canonical ensemble of a general Hamiltonian, which consists of not-too-long-range interactions.

Energetic band structure of Zn{sub 3}P{sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Stamov, I.G. [Tiraspol State Corporative University, Lablocicin Street 5, 2069 Tiraspol (Moldova, Republic of); Syrbu, N.N., E-mail: sirbunn@yahoo.com [Technical University of Moldova, 168 Stefan cel Mare Avenue, 2004 Chisinau (Moldova, Republic of); Dorogan, A.V. [Technical University of Moldova, 168 Stefan cel Mare Avenue, 2004 Chisinau (Moldova, Republic of)

2013-01-01

Optical functions n, k, {epsilon}{sub 1}, {epsilon}{sub 2} and d{sup 2}{epsilon}{sub 2}/dE{sup 2} have been determined from experimental reflection spectra in the region of 1-10 eV. The revealed electronic transitions are localized in the Brillouin zone. The magnitude of valence band splitting caused by the spin-orbital interaction {Delta}{sub SO} is lower than the splitting caused by the crystal field {Delta}{sub CR} in the center of Brillouin zone and L and X points. The switching effects are investigated in Zn{sub 3}P{sub 2} crystals. The characteristics of experimental samples with electric switching, adjustable resistors, and time relays based on Zn{sub 3}P{sub 2} are presented.

Optical Cherenkov radiation by cascaded nonlinear interaction: an efficient source of few-cycle energetic near- to mid-IR pulses

DEFF Research Database (Denmark)

Bache, Morten; Bang, Ole; Zhou, Binbin

2011-01-01

When ultrafast noncritical cascaded second-harmonic generation of energetic femtosecond pulses occur in a bulk lithium niobate crystal optical Cherenkov waves are formed in the near- to mid-IR. Numerical simulations show that the few-cycle solitons radiate Cherenkov (dispersive) waves in the λ = 2...

Resolving ultrafast exciton migration in organic solids at the nanoscale

Science.gov (United States)

Ginsberg, Naomi

The migration of Frenkel excitons, tightly-bound electron-hole pairs, in photosynthesis and in organic semiconducting films is critical to the efficiency of natural and artificial light harvesting. While these materials exhibit a high degree of structural heterogeneity on the nanoscale, traditional measurements of exciton migration lengths are performed on bulk samples. Since both the characteristic length scales of structural heterogeneity and the reported bulk diffusion lengths are smaller than the optical diffraction limit, we adapt far-field super-resolution fluorescence imaging to uncover the correlations between the structural and energetic landscapes that the excitons explore. By combining the ultrafast super-resolved measurements with exciton hopping simulations we furthermore specify the nature (in addition to the extent) of exciton migration as a function of the intrinsic and ensemble chromophore energy scales that determine a spatio-energetic landscape for migration. In collaboration with: Samuel Penwell, Lucas Ginsberg, University of California, Berkeley and Rodrigo Noriega University of Utah.

Energetic Mapping of Ni Catalysts by Detailed Kinetic Modeling

DEFF Research Database (Denmark)

Bjørgum, Erlend; Chen, De; Bakken, Mari G.

2005-01-01

Temperature-programmed desorption (TPD) of CO has been performed on supported and unsupported nickel catalysts. The unsupported Ni catalyst consists of a Ni(14 13 13) single crystal which has been studied under ultrahigh vacuum conditions. The desorption energy for CO at low CO surface coverage...... was found to be 119 kJ/mol, and the binding energy of C to the Ni(111) surface of the crystal was 703 kJ/mol. The supported catalysts consist of nickel supported on hydrotalcite-like compounds with three different Mg2+/Al3+ ratios. The experimental results show that for the supported Ni catalysts TPD of CO...... precursor seems to result in more steplike sites, kinks, and defects for carbon monoxide dissociation. A detailed kinetic modeling of the TPO results based on elementary reaction steps has been conducted to give an energetic map of supported Ni catalysts. Experimental results from the ideal Ni surface fit...

X-ray streak crystal spectography

International Nuclear Information System (INIS)

Kauffman, R.L.; Brown, T.; Medecki, H.

1983-01-01

We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11 0 to 38 0 and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/δE > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given

Spatially resolved observation of crystal-face-dependent catalysis by single turnover counting

Science.gov (United States)

Roeffaers, Maarten B. J.; Sels, Bert F.; Uji-I, Hiroshi; de Schryver, Frans C.; Jacobs, Pierre A.; de Vos, Dirk E.; Hofkens, Johan

2006-02-01

Catalytic processes on surfaces have long been studied by probing model reactions on single-crystal metal surfaces under high vacuum conditions. Yet the vast majority of industrial heterogeneous catalysis occurs at ambient or elevated pressures using complex materials with crystal faces, edges and defects differing in their catalytic activity. Clearly, if new or improved catalysts are to be rationally designed, we require quantitative correlations between surface features and catalytic activity-ideally obtained under realistic reaction conditions. Transmission electron microscopy and scanning tunnelling microscopy have allowed in situ characterization of catalyst surfaces with atomic resolution, but are limited by the need for low-pressure conditions and conductive surfaces, respectively. Sum frequency generation spectroscopy can identify vibrations of adsorbed reactants and products in both gaseous and condensed phases, but so far lacks sensitivity down to the single molecule level. Here we adapt real-time monitoring of the chemical transformation of individual organic molecules by fluorescence microscopy to monitor reactions catalysed by crystals of a layered double hydroxide immersed in reagent solution. By using a wide field microscope, we are able to map the spatial distribution of catalytic activity over the entire crystal by counting single turnover events. We find that ester hydrolysis proceeds on the lateral {1010} crystal faces, while transesterification occurs on the entire outer crystal surface. Because the method operates at ambient temperature and pressure and in a condensed phase, it can be applied to the growing number of liquid-phase industrial organic transformations to localize catalytic activity on and in inorganic solids. An exciting opportunity is the use of probe molecules with different size and functionality, which should provide insight into shape-selective or structure-sensitive catalysis and thus help with the rational design of new or

Solar wind heavy ions from energetic coronal events

International Nuclear Information System (INIS)

Bame, S.J.

1978-01-01

Ions heavier than those of He can be resolved in the solar wind with electrostatic E/q analyzers when the local thermal temperatures are low. Ordinarily this condition prevails in the low speed solar wind found between high speed streams, i.e. the interstream, IS, solar wind. Various ions of O, Si and Fe are resolved in IS heavy ion spectra. Relative ion peak intensities indicate that the O ionization state is established in the IS coronal source regions at approx. 2.1 x 10 6 K while the state of Fe is frozen in at approx. 1.5 x 10 6 K farther out. Occasionally, anomalous spectra are observed in which the usually third most prominent ion peak, O 8+ , is depressed as are the Fe peaks ranging from Fe 12+ to Fe 7+ . A prominent peak in the usual Si 8+ position of IS spectra is self-consistently shown to be Fe 16+ . These features demonstrate that the ionization states were frozen in at higher than usual coronal temperatures. The source regions of these hot heavy ion spectra are identified as energetic coronal events including flares and nonflare coronal mass ejections. 24 references

Simultaneously time- and space-resolved spectroscopic characterization of laser-produced plasmas

International Nuclear Information System (INIS)

Charatis, G.; Young, B.K.F.; Busch, G.E.

1988-01-01

The CHROMA laser facility at KMS Fusion has been used to irradiate a variety of microdot targets. These include aluminum dots and mixed bromine dots doped with K-shell (magnesium) emitters. Simultaneously time- and space-resolved K-shell and L-shell spectra have been measured and compared to dynamic model predictions. The electron density profiles are measured using holographic interferometry. Temperatures, densities, and ionization distributions are determined using K-shell and L-shell spectral techniques. Time and spatial gradients are resolved simultaneously using three diagnostics: a framing crystal x-ray spectrometer, an x-ray streaked crystal spectrometer with a spatial imaging slit, and a 4-frame holographic interferometer. Significant differences have been found between the interferometric and the model-dependent spectral measurements of plasma density. Predictions by new non-stationary L-shell models currently being developed are also presented. 14 refs., 10 figs

Theoretical study of Cherenkov radiation emission in anisotropic uniaxial crystals

Energy Technology Data Exchange (ETDEWEB)

Delbart, A; Derre, J

1996-04-01

A theoretical review of the Cherenkov radiation emission in uniaxial crystals is presented. The formalism of C. Muzicar in terms of energetic properties of the emitted waves are corrected. This formalism is used to simulate the Cherenkov radiation emission in a strongly birefringent sodium nitrate crystal (NaNO{sub 3}) and to investigate the consequences of the slight anisotropy of sapphire (Al{sub 2}O{sub 3}) on the design of the Optical Trigger. (author). 12 refs. Submitted to Physical Review, D (US).

An x-ray detector for time-resolved studies

International Nuclear Information System (INIS)

Rodricks, B.; Brizard, C.; Clarke, R.; Lowe, W.

1992-01-01

The development of ultrahigh-brightness x-ray sources makes time-resolved x-ray studies more and more feasible. Improvements in x-ray optics components are also critical for obtaining the appropriate beam for a particular type of experiment. Moreover, fast parallel detectors will be essential in order to exploit the combination of high intensity x-ray sources and novel optics for time-resolved experiments. A CCD detector with a time resolution of microseconds has been developed at the Advanced Photon Source (APS). This detector is fully programmable using CAMAC electronics and a Micro Vax computer. The techniques of time-resolved x-ray studies, which include scattering, microradiography, microtomography, stroboscopy, etc., can be applied to a range of phenomena (including rapid thermal annealing, surface ordering, crystallization, and the kinetics of phase transition) in order to understand these time-dependent microscopic processes. Some of these applications will be illustrated by recent results performed at synchrotrons. New powerful x-ray sources now under construction offer the opportunity to apply innovative approaches in time-resolved work

Mix and Inject: Reaction Initiation by Diffusion for Time-Resolved Macromolecular Crystallography

Directory of Open Access Journals (Sweden)

Marius Schmidt

2013-01-01

Full Text Available Time-resolved macromolecular crystallography unifies structure determination with chemical kinetics, since the structures of transient states and chemical and kinetic mechanisms can be determined simultaneously from the same data. To start a reaction in an enzyme, typically, an initially inactive substrate present in the crystal is activated. This has particular disadvantages that are circumvented when active substrate is directly provided by diffusion. However, then it is prohibitive to use macroscopic crystals because diffusion times become too long. With small micro- and nanocrystals diffusion times are adequately short for most enzymes and the reaction can be swiftly initiated. We demonstrate here that a time-resolved crystallographic experiment becomes feasible by mixing substrate with enzyme nanocrystals which are subsequently injected into the X-ray beam of a pulsed X-ray source.

Computational Study on Substituted s-Triazine Derivatives as Energetic Materials

Directory of Open Access Journals (Sweden)

Vikas D. Ghule

2012-01-01

Full Text Available s-Triazine is the essential candidate of many energetic compounds due to its high nitrogen content, enthalpy of formation and thermal stability. The present study explores s-triazine derivatives in which different -NO2, -NH2 and -N3 substituted azoles are attached to the triazine ring via C-N linkage. The density functional theory is used to predict geometries, heats of formation and other energetic properties. Among the designed compounds, -N3 derivatives show very high heats of formation. The densities for designed compounds were predicted by using the crystal packing calculations. Introduction of -NO2 group improves density as compared to -NH2 and -N3, their order of increasing density can be given as NO2>N3>NH2. Analysis of the bond dissociation energies for C-NO2, C-NH2 and C-N3 bonds indicates that substitutions of the -N3 and -NH2 group are favorable for enhancing the thermal stability of s-triazine derivatives. The nitro and azido derivatives of triazine are found to be promising candidates for the synthetic studies.

Electrical initiation of an energetic nanolaminate film

Science.gov (United States)

Tringe, Joseph W.; Gash, Alexander E.; Barbee, Jr., Troy W.

2010-03-30

A heating apparatus comprising an energetic nanolaminate film that produces heat when initiated, a power source that provides an electric current, and a control that initiates the energetic nanolaminate film by directing the electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature. Also a method of heating comprising providing an energetic nanolaminate film that produces heat when initiated, and initiating the energetic nanolaminate film by directing an electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature.

Twinning of Polymer Crystals Suppressed by Entropy

Directory of Open Access Journals (Sweden)

Nikos Ch. Karayiannis

2014-09-01

Full Text Available We propose an entropic argument as partial explanation of the observed scarcity of twinned structures in crystalline samples of synthetic organic polymeric materials. Polymeric molecules possess a much larger number of conformational degrees of freedom than low molecular weight substances. The preferred conformations of polymer chains in the bulk of a single crystal are often incompatible with the conformations imposed by the symmetry of a growth twin, both at the composition surfaces and in the twin axis. We calculate the differences in conformational entropy between chains in single crystals and chains in twinned crystals, and find that the reduction in chain conformational entropy in the twin is sufficient to make the single crystal the stable thermodynamic phase. The formation of cyclic twins in molecular dynamics simulations of chains of hard spheres must thus be attributed to kinetic factors. In more realistic polymers this entropic contribution to the free energy can be canceled or dominated by nonbonded and torsional energetics.

The role of crystal orientation and surface proximity in the self-similar behavior of deformed Cu single crystals

Energy Technology Data Exchange (ETDEWEB)

Pang, Judy W.L., E-mail: pangj@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Behtel Valley Road, Oak Ridge, TN 37831 (United States); Ice, Gene E. [Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Behtel Valley Road, Oak Ridge, TN 37831 (United States); Liu Wenjun [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2010-11-25

We report on novel 3D spatially resolved X-ray diffraction microscopy studies of self-affine behavior in deformed single crystals. This study extends surface profile measurements of self-affined morphology changes in single crystals during deformation to include local lattice rotations and sub-surface behavior. Investigations were made on the spatial correlation of the local lattice rotations in 8% tensile deformed Cu single crystals oriented with [1 2 3], [1 1 1] and [0 0 1] axes parallel to the tensile axis. The nondestructive depth-resolved measurements were made over a length scale of one to hundreds of micrometers. Self-affined correlation was found both at the surface and below the surface of the samples. A universal exponent for the power-law similar to that observed with surface profile methods is found at the surface of all samples but crystallographically sensitive changes are observed as a function of depth. Correlation lengths of the self-affine behavior vary with the [1 2 3] crystal exhibiting the longest self-affine length scale of 70 {mu}m with only 18 {mu}m for the [1 1 1] and [0 0 1] crystals. These measurements illuminate the transition from surface-like to bulk-like deformation behavior and provide new quantitative information to guide emerging models of self-organized structures in plasticity.

Life-time resolved emission spectra in CdI2 crystals

International Nuclear Information System (INIS)

Kawabata, Seiji; Nakagawa, Hideyuki

2007-01-01

The emission spectrum of CdI 2 is composed of ultraviolet (UV), green (G) and yellow (Y and Y') bands peaking at 3.38, 2.50, 2.16 and 2.25 eV, respectively. In order to determine the initial states of the Y- and G-luminescence, decay curves have been measured at 6 and 80 K by varying emission energy. The observed decay curves are composed of two or three exponential components. These decay components were named τ 1 , τ 2 , τ 3 , τ 3' and τ 4 . The emission spectrum for each decay component, i.e., the life-time resolved emission spectrum, was constructed from the observed decay curves. At 6 K, three bands at 2.12, 2.49 and 2.64 eV are obtained for τ 1 , τ 2 and τ 3 components, respectively. At 80 K, a dominant band for the τ 4 component and a weak band for the τ 3' component appear on the same energy position at 2.25 eV. The origin of each emission band in the life-time resolved emission spectra will be briefly discussed

Molecular dynamics calculations of defect energetics in β-SiC

International Nuclear Information System (INIS)

Huang, H.; El-Azab, A.; Ghoniem, N.

1993-01-01

The Molecular Dynamics (MD) method is used to calculate defect energetics in β-silicon carbide. Many-body interaction effects in this covalent material are accounted for by using a hybrid of two-body and three-body potentials. Calculated bulk properties of β-SiC based on this potential are in agreement with experimental data to within 17%. A micro-crystal is constructed to represent the computational cell and external forces are applied to the micro-crystal so that it behaves as a part of an infinite medium. The potential energy for the unperturbed computational cell is first calculated. The cell is then set at a defect configuration and relaxed, and the potential energy of the relaxed cell is calculated. The difference between the potential energy of the unperturbed cell and that of the defect-containing cell is used to calculate the formation and binding energies of point defects, defect clusters and helium-vacancy clusters in SiC

Sensitivity Characterization of Pressed Energetic Materials using Flyer Plate Mesoscale Simulations

Science.gov (United States)

Rai, Nirmal; Udaykumar, H. S.

Heterogeneous energetic materials like pressed explosives have complicated microstructure and contain various forms of heterogeneities such as pores, micro-cracks, energetic crystals etc. It is widely accepted that the presence of these heterogeneities can affect the sensitivity of these materials under shock load. The interaction of shock load with the microstructural heterogeneities may leads to the formation of local heated regions known as ``hot spots''. Chemical reaction may trigger at the hot spot regions depending on the hot spot temperature and the duration over which the temperature can be maintained before phenomenon like heat conduction, rarefaction waves withdraws energy from it. There are different mechanisms which can lead to the formation of hot spots including void collapse. The current work is focused towards the sensitivity characterization of two HMX based pressed energetic materials using flyer plate mesoscale simulations. The aim of the current work is to develop mesoscale numerical framework which can perform simulations by replicating the laboratory based flyer plate experiments. The current numerical framework uses an image processing approach to represent the microstructural heterogeneities incorporated in a massively parallel Eulerian code SCIMITAR3D. The chemical decomposition of HMX is modeled using Henson-Smilowitz reaction mechanism. The sensitivity characterization is aimed towards obtaining James initiation threshold curve and comparing it with the experimental results.

Co-crystallization: An approach to improve the performance characteristics of active pharmaceutical ingredients

OpenAIRE

Jignasa Ketan Savjani

2015-01-01

Co-crystal chemistry has recently attracted supramolecular scientists. Co-crystals are comprising of hydrogen boding assembly between different molecules. Many issues related to performance characteristics of an active pharmaceutical ingredient (API) can be resolved using co-crystallization approach. Proper understanding of crystal structure of an API is required for successful formation of co-crystals with the selected co-former. This review article focus on explanation about co-crystals, in...

Use of Resolving Equation to Define the Lower Critical Reynolds Number

Directory of Open Access Journals (Sweden)

Alexander A. Solovyev

2014-09-01

Full Text Available Although the issue of streams with non-crossing trajectories of particle motions ranging from chaotic, random with irregular current lines, has been given a lot of attention, it still remains unresolved. The study features a relevant issue for hydromechanics, which is precise values determination of the Lower Critical Reynolds Number. It is suggested to put forward an updated approach to the use of energetic analysis for analytical calculation of the Reynolds Resolving Equation. The assessment of transition to mean motion from pulsation to the direction of laminar flows was fulfilled.

Helium Energetic Neutral Atoms from the Heliosphere: Perspectives for Future Observations

Energy Technology Data Exchange (ETDEWEB)

Swaczyna, Paweł; Grzedzielski, Stan; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl [Space Research Centre of the Polish Academy of Sciences (CBK PAN), Bartycka 18A, 00-716 Warsaw (Poland)

2017-05-10

Observations of energetic neutral atoms (ENAs) allow for remote sensing of plasma properties in distant regions of the heliosphere. So far, most of the observations have concerned only hydrogen atoms. In this paper, we present perspectives for observations of helium energetic neutral atoms (He ENAs). We calculated the expected intensities of He ENAs created by the neutralization of helium ions in the inner heliosheath and through the secondary ENA mechanism in the outer heliosheath. We found that the dominant source region for He ENAs is the inner heliosheath. The obtained magnitudes of intensity spectra suggest that He ENAs can be observed with future ENA detectors, as those planned on Interstellar Mapping and Acceleration Probe . Observing He ENAs is most likely for energies from a few to a few tens of keV/nuc. Estimates of the expected count rates show that the ratio of helium to hydrogen atoms registered in the detectors can be as low as 1:10{sup 4}. Consequently, the detectors need to be equipped with an appropriate mass spectrometer capability, allowing for recognition of chemical elements. Due to the long mean free paths of helium ions in the inner heliosheath, He ENAs are produced also in the distant heliospheric tail. This implies that observations of He ENAs can resolve its structure, which seems challenging from observations of hydrogen ENAs since energetic protons are neutralized before they progress deeper in the heliospheric tail.

About Russian nuclear energetic perspectives

International Nuclear Information System (INIS)

Laletin, N.I.

2003-01-01

My particular view about Russian nuclear energetics perspectives is presented. The nearest and the further perspectives are considered. The arguments are adduced that the most probable scenario of nuclear energetic development is its stabilization in the near future. Fur further development the arguments of supporters and opponents of nuclear energetics are analyzed. Three points of view are considered. The first point of view that there is not alternative for nuclear energetics. My notes are the following ones. a) I express a skeptic opinion about a statement of quick exhaustion of fossil organic fuel recourses and corresponding estimations are presented. b) It is expressed skeptic opinion about the statement that nuclear energetics can have a visual influence on ''steam effect''. c) I agree that nuclear energetics is the most ecological technology for normal work but however we can't disregard possibilities of catastrophic accidents. The second point of view that the use of nuclear energetics can't have the justification. I adduce the arguments contrary to this statement. The third point of view that nuclear energetics is a usual technology and the only criteria for discussions about what dimension and where one ought develop it is total cost of its unit. Expressed an opinion that the deceived for the choose of a way the skill of the estimate correctly and optimized so named the external parts of the unit energy costs for different energy technologies. (author)

A diagnostic for time-resolved spatial profiles measurements on the ion temperature on JET

International Nuclear Information System (INIS)

Brocken, H.J.B.M.; Ven, H.W van der.

1980-05-01

A neutral particle scattering experiment for a continuous measurement of the ion temperature and ion density of the JET plasma in the hydrogen and deuterium phase is proposed. Space- and time-resolved measurements are possible by injection of a mono-energetic particle beam into the plasma and from the analysis of the velocity distribution of the scattered particles. The requirements on the injection system are specified and a suitable analyzer system is described

Observation of enhanced radial transport of energetic ion due to energetic particle mode destabilized by helically-trapped energetic ion in the Large Helical Device

Science.gov (United States)

Ogawa, K.; Isobe, M.; Kawase, H.; Nishitani, T.; Seki, R.; Osakabe, M.; LHD Experiment Group

2018-04-01

A deuterium experiment was initiated to achieve higher-temperature and higher-density plasmas in March 2017 in the Large Helical Device (LHD). The central ion temperature notably increases compared with that in hydrogen experiments. However, an energetic particle mode called the helically-trapped energetic-ion-driven resistive interchange (EIC) mode is often excited by intensive perpendicular neutral beam injections on high ion-temperature discharges. The mode leads to significant decrease of the ion temperature or to limiting the sustainment of the high ion-temperature state. To understand the effect of EIC on the energetic ion confinement, the radial transport of energetic ions is studied by means of the neutron flux monitor and vertical neutron camera newly installed on the LHD. Decreases of the line-integrated neutron profile in core channels show that helically-trapped energetic ions are lost from the plasma.

Analysis of the energetic sector through the national energetic matrix

International Nuclear Information System (INIS)

Garzon Lozano, Enrique

2007-01-01

The author shows the results of the national energetic balance 1975-2005, through the energetic matrix of the country, giving an annual growth of 5.1% in this period of offer of primary energy, where the mineral coal participates with 9,6%, the hydraulic energy with 4,8%, natural gas with 4,2%, trash with 2,4% and petroleum with 2,2%, while the firewood fell in 0,5%

Energetics and crystal chemistry of Ruddlesden-Popper type structures in high T(sub c) ceramic superconductors

Science.gov (United States)

Dwivedi, Anurag; Cormack, A. N.

1990-01-01

The formation of Ruddlesden-Popper type layers (alternating slabs of rocksalt and perovskite structures) is seen in these oxides which is similar in many respects to what is seen in the system Sr-Ti-O. However, it was observed that there are some significant differences, for example the rocksalt and perovskite blocks in new superconducting compounds are not necessarily electrically, unlike in Sr-Ti-O systems. This will certainly render an additional coulombic bonding energy between two different types of blocks and may well lead to significant differences in their structural chemistry. In the higher order members of the various homologous series, additional Cu-O planes are inserted in the perovskite blocks. In order for the unit cell to electrically neutral the net positive charge on rocksalt block (which remains constant throughout the homologous series) should be balanced by an equal negative charge on perovskite block. It, thus becomes necessary to create oxygen vacancies in the basic perovskite structure, when width of the perovskite slab changes on addition of extra Cu-O planes. Results of atomistic simulations suggest that these missing oxygen ions allow the Cu-O planes to buckle in these compounds. This is also supported by the absence of buckling in the first member of Bi-containing compounds in which there are no missing oxygen ions and the Sr-Ti-O series of compounds. Additional results are presented on the phase stability of polytypoid structures in these crystal chemically complex systems. The studies will focus on the determination of the location of Cu(3+) in the structures of higher order members of the La-Cu-O system and whether Cu(3+) ions or oxygen vacancies are energetically more favorable charge compensating mechanism.

Infrared dispersion analysis and Raman scattering spectra of taurine single crystals

Science.gov (United States)

Moreira, Roberto L.; Lobo, Ricardo P. S. M.; Dias, Anderson

2018-01-01

A comprehensive set of optical vibrational modes of monoclinic taurine crystals was determined by Raman scattering, and infrared reflectivity and transmission spectroscopies. By using appropriate scattering/reflection geometries, the vibrational modes were resolved by polarization and the most relevant modes of the crystal could be assigned. In particular, we were able to review the symmetry of the gerade modes and to resolve ambiguities in the literature. Owing to the non-orthogonal character of Bu modes in monoclinic crystals (lying on the optic axial plane), we carried out a generalized Lorentz dispersion analysis consisting of simultaneous adjust of infrared-reflectivity spectra at various light polarization angles. The Au modes (parallel to the C2-axis) were treated within the classical Lorentz model. The behavior of off-diagonal and diagonal terms of the complex dielectric tensors and the presence of anomalous dispersion were discussed as consequences of the low symmetry of the crystal.

Crystallization behavior of polyethylene on silicon wafers in solution casting processes traced by time-resolved measurements of synchrotron grazing-incidence small-angle and wide-angle X-ray scattering

International Nuclear Information System (INIS)

Sasaki, S; Masunaga, H; Takata, M; Itou, K; Tashiro, K; Okuda, H; Takahara, A

2009-01-01

Crystallization behavior of polyethylene (PE) on silicon wafers in solution casting processes has been successfully traced by time-resolved grazing-incidence small-angle and wide-angle X-ray scattering (GISWAXS) measurements utilizing synchrotron radiation. A p-xylene solution of PE kept at ca. 343 K was dropped on a silicon wafer at ca. 298 K. While the p-xylene evaporated naturally from the dropped solution sample, PE chains crystallized to be a thin film. Raman spectral measurements were performed simultaneously with the GISWAXS measurements to evaluate quantitatively the p-xylene the dropped solution contained. Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns indicated nucleation and crystal growth in the dropped solution and the following as-cast film. GIWAXS and Raman spectral data revealed that crystallization of PE was enhanced after complete evaporation of the p-xylene from the dropped solution. The [110] and [200] directions of the orthorhombic PE crystal became relatively parallel to the wafer surface with time, which implied that the flat-on lamellae with respect to the wafer surface were mainly formed in the as-cast film. On the other hand, grazing-incidence small-angle X-ray scattering (GISAXS) patterns implied formation of isolated lamellae in the dropped solution. The lamellae and amorphous might alternatively be stacked in the preferred direction perpendicular to the wafer surface. The synchrotron GISWAXS experimental method could be applied for kinetic study on hierarchical structure of polymer thin films.

Design and operation of the pellet charge exchange diagnostic for measurement of energetic confined alphas and tritons on TFTR

International Nuclear Information System (INIS)

Medley, S.S.; Duong, H.H.

1996-05-01

Radially-resolved energy and density distributions of the energetic confined alpha particles in D-T experiments on TFTR are being measured by active neutral particle analysis using low-Z impurity pellet injection. When injected into a high temperature plasma, an impurity pellet (e.g. Lithium or Boron) rapidly ablates forming an elongated cloud which is aligned with the magnetic field and moves with the pellet. This ablation cloud provides a dense target with which the alpha particles produced in D-T fusion reactions can charge exchange. A small fraction of the alpha particles incident on the pellet ablation cloud will be converted to helium neutrals whose energy is essentially unchanged by the charge transfer process. By measuring the resultant helium neutrals escaping from the plasma using a mass and energy resolving charge exchange analyzer, this technique offers a direct measurement of the energy distribution of the incident high-energy alpha particles. Other energetic ion species can be detected as well, such as tritons generated in D-D plasmas and H or He 3 RF-driven minority ion tails. The diagnostic technique and its application on TFTR are described in detail

Flare energetics

Science.gov (United States)

Wu, S. T.; Dejager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.

1986-01-01

In this investigation of flare energetics, researchers sought to establish a comprehensive and self-consistent picture of the sources and transport of energy within a flare. To achieve this goal, they chose five flares in 1980 that were well observed with instruments on the Solar Maximum Mission, and with other space-borne and ground-based instruments. The events were chosen to represent various types of flares. Details of the observations available for them and the corresponding physical parameters derived from these data are presented. The flares were studied from two perspectives, the impulsive and gradual phases, and then the results were compared to obtain the overall picture of the energics of these flares. The role that modeling can play in estimating the total energy of a flare when the observationally determined parameters are used as the input to a numerical model is discussed. Finally, a critique of the current understanding of flare energetics and the methods used to determine various energetics terms is outlined, and possible future directions of research in this area are suggested.

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

International Nuclear Information System (INIS)

Rutherford, Michael E.; Chapman, David J.; White, Thomas G.; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E.

2016-01-01

Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

Energy Technology Data Exchange (ETDEWEB)

Rutherford, Michael E.; Chapman, David J.; White, Thomas G. [Imperial College London, London (United Kingdom); Drakopoulos, Michael [Diamond Light Source, I12 Joint Engineering, Environmental, Processing (JEEP) Beamline, Didcot, Oxfordshire (United Kingdom); Rack, Alexander [European Synchrotron Radiation Facility, Grenoble (France); Eakins, Daniel E., E-mail: d.eakins@imperial.ac.uk [Imperial College London, London (United Kingdom)

2016-03-24

Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

Development of soft x-ray time-resolved photoemission spectroscopy system with a two-dimensional angle-resolved time-of-flight analyzer at SPring-8 BL07LSU

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Manami; Yamamoto, Susumu; Nakamura, Fumitaka; Yukawa, Ryu; Fukushima, Akiko; Harasawa, Ayumi; Kakizaki, Akito; Matsuda, Iwao [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581 (Japan); Kousa, Yuka; Kondoh, Hiroshi [Department of Chemistry, Keio University, Yokohama 223-8522 (Japan); Tanaka, Yoshihito [RIKEN/SPring-8 Center, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2012-02-15

We have developed a soft x-ray time-resolved photoemission spectroscopy system using synchrotron radiation (SR) at SPring-8 BL07LSU and an ultrashort pulse laser system. Two-dimensional angle-resolved measurements were performed with a time-of-flight-type analyzer. The photoemission spectroscopy system is synchronized to light pulses of SR and laser using a time control unit. The performance of the instrument is demonstrated by mapping the band structure of a Si(111) crystal over the surface Brillouin zones and observing relaxation of the surface photo-voltage effect using the pump (laser) and probe (SR) method.

Recent trends in spin-resolved photoelectron spectroscopy

Science.gov (United States)

Okuda, Taichi

2017-12-01

Since the discovery of the Rashba effect on crystal surfaces and also the discovery of topological insulators, spin- and angle-resolved photoelectron spectroscopy (SARPES) has become more and more important, as the technique can measure directly the electronic band structure of materials with spin resolution. In the same way that the discovery of high-Tc superconductors promoted the development of high-resolution angle-resolved photoelectron spectroscopy, the discovery of this new class of materials has stimulated the development of new SARPES apparatus with new functions and higher resolution, such as spin vector analysis, ten times higher energy and angular resolution than conventional SARPES, multichannel spin detection, and so on. In addition, the utilization of vacuum ultra violet lasers also opens a pathway to the realization of novel SARPES measurements. In this review, such recent trends in SARPES techniques and measurements will be overviewed.

Enzyme reactions and their time resolved measurements

International Nuclear Information System (INIS)

Hajdu, Janos

1990-01-01

This paper discusses experimental strategies in data collection with the Laue method and summarises recent results using synchrotron radiation. Then, an assessment is made of the progress towards time resolved studies with protein crystals and the problems that remain. The paper consists of three parts which respectively describe some aspects of Laue diffraction, recent examples of structural results from Laue diffraction, and kinetic Laue crystallography. In the first part, characteristics of Laue diffraction is discussed first, focusing on the harmonics problems, spatials problem, wavelength normalization, low resolution hole, data completeness, and uneven coverage of reciprocal space. Then, capture of the symmetry unique reflection set is discussed focusing on the effect of wavelength range on the number of reciprocal lattice points occupying diffracting positions, effect of crystal to film distance and the film area and shape on the number of reflections captured, and effect of crystal symmetry on the number of unique reflections within the number of reflections captured. The second part addresses the determination of the structure of turkey egg white lysozyme, and calcium binding in tomato bushy stunt virus. The third part describes the initiation of reactions in enzyme crystals, picosecond Laue diffraction at high energy storage rings, and detectors. (N.K.)

Temperature dependence of critical resolved shear stress for cubic metals

International Nuclear Information System (INIS)

Rashid, H.; Fazal-e-Aleem; Ali, M.

1996-01-01

The experimental measurements for critical resolved shear stress of various BCC and FCC metals have been explained by using Radiation Model. The temperature dependence of CRSS for different cubic metals is found to the first approximation, to upon the type of the crystal. A good agreement between experimental observations and predictions of the Radiation Model is found. (author)

Nonlinear spin wave coupling in adjacent magnonic crystals

Energy Technology Data Exchange (ETDEWEB)

Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

2016-07-25

We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

Nonlinear spin wave coupling in adjacent magnonic crystals

International Nuclear Information System (INIS)

Sadovnikov, A. V.; Nikitov, S. A.; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Grishin, S. V.; Sheshukova, S. E.

2016-01-01

We have experimentally studied the coupling of spin waves in the adjacent magnonic crystals. Space- and time-resolved Brillouin light-scattering spectroscopy is used to demonstrate the frequency and intensity dependent spin-wave energy exchange between the side-coupled magnonic crystals. The experiments and the numerical simulation of spin wave propagation in the coupled periodic structures show that the nonlinear phase shift of spin wave in the adjacent magnonic crystals leads to the nonlinear switching regime at the frequencies near the forbidden magnonic gap. The proposed side-coupled magnonic crystals represent a significant advance towards the all-magnonic signal processing in the integrated magnonic circuits.

Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy.

Science.gov (United States)

Chen, Ming-Wei; You, Sizhu; Suslick, Kenneth S; Dlott, Dana D

2014-02-01

We have observed and characterized hot spot formation and hot-spot ignition of energetic materials (EM), where hot spots were created by ultrasonic or long-wavelength infrared (LWIR) exposure, and were detected by high-speed thermal microscopy. The microscope had 15-20 μm spatial resolution and 8.3 ms temporal resolution. LWIR was generated by a CO2 laser (tunable near 10.6 μm or 28.3 THz) and ultrasound by a 20 kHz acoustic horn. Both methods of energy input created spatially homogeneous energy fields, allowing hot spots to develop spontaneously due to the microstructure of the sample materials. We observed formation of hot spots which grew and caused the EM to ignite. The EM studied here consisted of composite solids with 1,3,5-trinitroperhydro-1,3,5-triazine crystals and polymer binders. EM simulants based on sucrose crystals in binders were also examined. The mechanisms of hot spot generation were different with LWIR and ultrasound. With LWIR, hot spots were most efficiently generated within the EM crystals at LWIR wavelengths having longer absorption depths of ∼25 μm, suggesting that hot spot generation mechanisms involved localized absorbing defects within the crystals, LWIR focusing in the crystals or LWIR interference in the crystals. With ultrasound, hot spots were primarily generated in regions of the polymer binder immediately adjacent to crystal surfaces, rather than inside the EM crystals.

Musical Tasks and Energetic Arousal.

Science.gov (United States)

Lim, Hayoung A; Watson, Angela L

2018-03-08

Music is widely recognized as a motivating stimulus. Investigators have examined the use of music to improve a variety of motivation-related outcomes; however, these studies have focused primarily on passive music listening rather than active participation in musical activities. To examine the influence of participation in musical tasks and unique participant characteristics on energetic arousal. We used a one-way Welch's ANOVA to examine the influence of musical participation (i.e., a non-musical control and four different musical task conditions) upon energetic arousal. In addition, ancillary analyses of participant characteristics including personality, age, gender, sleep, musical training, caffeine, nicotine, and alcohol revealed their possible influence upon pretest and posttest energetic arousal scores. Musical participation yielded a significant relationship with energetic arousal, F(4, 55.62) = 44.38, p = .000, estimated ω2 = 0.60. Games-Howell post hoc pairwise comparisons revealed statistically significant differences between five conditions. Descriptive statistics revealed expected differences between introverts' and extraverts' energetic arousal scores at the pretest, F(1, 115) = 6.80, p = .010, partial η2= .06; however, mean differences failed to reach significance at the posttest following musical task participation. No other measured participant characteristics yielded meaningful results. Passive tasks (i.e., listening to a story or song) were related to decreased energetic arousal, while active musical tasks (i.e., singing, rhythm tapping, and keyboard playing) were related to increased energetic arousal. Musical task participation appeared to have a differential effect for individuals with certain personality traits (i.e., extroverts and introverts).

Dispersive waves induced by self-defocusing temporal solitons in a beta-barium-borate crystal

DEFF Research Database (Denmark)

Zhou, Binbin; Bache, Morten

2015-01-01

We experimentally observe dispersive waves in the anomalous dispersion regime of a beta-barium-borate (BBO) crystal, induced by a self-defocusing few-cycle temporal soliton. Together the soliton and dispersive waves form an energetic octave-spanning supercontinuum. The soliton was excited...

Light exiting from real photonic band gap crystals is diffuse and strongly directional

NARCIS (Netherlands)

Koenderink, A.F.; Vos, Willem L.

2003-01-01

Any photonic crystal is in practice periodic with some inevitable fabricational imperfections. We have measured angle-resolved transmission of photons that are multiply scattered by this disorder in strongly photonic crystals. Peculiar non-Lambertian distributions occur as a function of frequency:

Life-time resolved emission spectra in CdCl2 crystals

International Nuclear Information System (INIS)

Kawabata, S.; Nakagawa, H.; Kitaura, M.

2005-01-01

The emission spectrum of CdCl 2 is composed of ultraviolet (UV) and yellow (Y) bands peaking at 3.70 and 2.30 eV, respectively. In order to determine the initial states of the Y-luminescence, decay curves of the Y-emission were measured at 8K by varying emission energy in the range from 1.64 eV to 3.13 eV. The observed decay curves are composed of two or three exponential components. The values of lifetime for them were 900, 460 and 60 μs. The emission spectrum for each decay component, i.e., life-time resolved emission spectrum, was analyzed by the observed decay curves. The emission spectrum for the component of 460 μs lifetime exhibits a dominant band at 2.30 eV and a satellite band at 3.03 eV. The emission spectrum for the component of 60 μs lifetime is reproduced by the three Gaussian bands peaking at 2.21, 2.65 and 2.87 eV. For the component of 900 μs lifetime, only a single band appears at 1.73 eV. The origin of the emission bands in life-time resolved emission spectra is briefly discussed, and the initial states of Y-luminescence are explained by the excited states of a [Cd 2+ Cl - 6 ] 4- complex molecular ion. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

SIMULATION OF ENERGETIC NEUTRAL ATOMS FROM SOLAR ENERGETIC PARTICLES

Energy Technology Data Exchange (ETDEWEB)

Wang, Linghua [Institute of Space Physics and Applied Technology, Peking University, Beijing 100871 (China); Li, Gang [Department of Space Science and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Shih, Albert Y. [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20770 (United States); Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States); Wimmer-Schweingruber, Robert F., E-mail: wanglhwang@gmail.com [Institut fuer Experimentelle und Angewandte Physik, University of Kiel, Leibnizstrasse 11, D-24118 Kiel (Germany)

2014-10-01

Energetic neutral atoms (ENAs) provide the only way to observe the acceleration site of coronal-mass-ejection-driven (CME-driven) shock-accelerated solar energetic particles (SEPs). In gradual SEP events, energetic protons can charge exchange with the ambient solar wind or interstellar neutrals to become ENAs. Assuming a CME-driven shock with a constant speed of 1800 km s{sup –1} and compression ratio of 3.5, propagating from 1.5 to 40 R{sub S} , we calculate the accelerated SEPs at 5-5000 keV and the resulting ENAs via various charge-exchange interactions. Taking into account the ENA losses in the interplanetary medium, we obtain the flux-time profiles of these solar ENAs reaching 1 AU. We find that the arriving ENAs at energies above ∼100 keV show a sharply peaked flux-time profile, mainly originating from the shock source below 5 R{sub S} , whereas the ENAs below ∼20 keV have a flat-top time profile, mostly originating from the source beyond 10 R{sub S} . Assuming the accelerated protons are effectively trapped downstream of the shock, we can reproduce the STEREO ENA fluence observations at ∼2-5 MeV/nucleon. We also estimate the flux of ENAs coming from the charge exchange of energetic storm protons, accelerated by the fast CME-driven shock near 1 AU, with interstellar hydrogen and helium. Our results suggest that appropriate instrumentation would be able to detect ENAs from SEPs and to even make ENA images of SEPs at energies above ∼10-20 keV.

Radiation effects of energetic thorium ions in monocrystalline Mg O and Si O2

International Nuclear Information System (INIS)

Abuassy, M.K.

1995-01-01

Radiation effects of energetic thorium ions in the energy range ∼ (100-1200) eV in both Mg O and Si O 2 single crystal have been investigated with program MARLOWE which simulate the collision cascades using the binary collision approximation. The effect of binding parameters on the radiation effects have been studied. The calculations covered the range, energy loss and Frenkel pair production. The results of MARLOWE have been compared with results of program TRIM and with the energy-partition theory of lindhard

Photoactive energetic materials

Science.gov (United States)

Chavez, David E.; Hanson, Susan Kloek; Scharff, Robert Jason; Veauthier, Jacqueline Marie; Myers, Thomas Winfield

2018-02-27

Energetic materials that are photoactive or believed to be photoactive may include a conventional explosive (e.g. PETN, nitroglycerine) derivatized with an energetic UV-absorbing and/or VIS-absorbing chromophore such as 1,2,4,5-tetrazine or 1,3,5-triazine. Absorption of laser light having a suitably chosen wavelength may result in photodissociation, decomposition, and explosive release of energy. These materials may be used as ligands to form complexes. Coordination compounds include such complexes with counterions. Some having the formula M(L).sub.n.sup.2+ were synthesized, wherein M is a transition metal and L is a ligand and n is 2 or 3. These may be photoactive upon exposure to a laser light beam having an appropriate wavelength of UV light, near-IR and/or visible light. Photoactive materials also include coordination compounds bearing non-energetic ligands; in this case, the counterion may be an oxidant such as perchlorate.

Time-dependent first-principles study of angle-resolved secondary electron emission from atomic sheets

Science.gov (United States)

Ueda, Yoshihiro; Suzuki, Yasumitsu; Watanabe, Kazuyuki

2018-02-01

Angle-resolved secondary electron emission (ARSEE) spectra were analyzed for two-dimensional atomic sheets using a time-dependent first-principles simulation of electron scattering. We demonstrate that the calculated ARSEE spectra capture the unoccupied band structure of the atomic sheets. The excitation dynamics that lead to SEE have also been revealed by the time-dependent Kohn-Sham decomposition scheme. In the present study, the mechanism for the experimentally observed ARSEE from atomic sheets is elucidated with respect to both energetics and the dynamical aspects of SEE.

Differential charge-transfer cross sections for systems with energetically degenerate or near-degenerate channels

International Nuclear Information System (INIS)

Nguyen, H.; Bredy, R.; Camp, H.A.; DePaola, B.D.; Awata, T.

2004-01-01

Resolution plays a vital role in spectroscopic studies. In the usual recoil-ion momentum spectroscopy (RIMS), Q-value resolution is relied upon to distinguish between different collision channels: The better the Q-value resolution, the better one is able to resolve energetically similar channels. Although traditional COLTRIMS greatly improves Q-value resolution by cooling the target and thus greatly reducing the initial target momentum spread, the resolution of the technique is still limited by target temperature. However, with the recent development in RIMS, namely, magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) superior recoil ion momentum resolution as well as charge transfer measurements with laser excited targets have become possible. Through MOTRIMS, methods for the measurements of target excited state fraction and kinematically complete relative charge transfer cross sections have been developed, even for some systems having energetically degenerate or nearly degenerate channels. In the present work, the systems of interest having energy degeneracies or near degeneracies are Rb + , K + , and Li + colliding with trapped Rb(5l), where l=s and p

Continuous engineering of nano-cocrystals for medical and energetic applications

Science.gov (United States)

Spitzer, D.; Risse, B.; Schnell, F.; Pichot, V.; Klaumünzer, M.; Schaefer, M. R.

2014-10-01

Cocrystals, solid mixtures of different molecules on molecular scale, are supposed to be tailor made materials with improved employability compared to their pristine individual components in domains such as medicine and explosives. In medicine, cocrystals are obtained by crystallization of active pharmaceutical ingredients with precisely chosen coformers to design medicaments that demonstrate enhanced stability, high solubility, and therefore high bioavailability and optimized drug up-take. Nanoscaling may further advance these characteristica compared to their micronsized counterparts - because of a larger surface to volume ratio of nanoparticles. In the field of energetic materials, cocrystals offer the opportunity to design smart explosives, combining high reactivity with significantly reduced sensitivity, nowadays essential for a safe manipulation and handling. Furthermore, cocrystals are used in ferroelectrics, non-linear material response and electronic organics. However, state of the art batch processes produce low volume of cocrystals of variable quality and only have produced micronsized cocrystals so far, no nano-cocrystals. Here we demonstrate the continuous preparation of pharmaceutical and energetic micro- and nano-cocrystals using the Spray Flash Evaporation process. Our laboratory scale pilot plant continuously prepared up to 8 grams per hour of Caffeine/Oxalic acid 2:1, Caffeine/Glutaric acid 1:1, TNT/CL-20 1:1 and HMX/Cl-20 1:2 nano- and submicronsized cocrystals.

2016 Energetic Materials Gordon Research Conference and Gordon Research Seminar Research Area 7: Chemical Sciences 7.0 Chemical Sciences (Dr. James K. Parker)

Science.gov (United States)

2016-08-10

Energetic Materials" 8:45 pm - 8:55 pm Discussion 8:55 pm - 9:20 pm Michael Zdilla (Temple University, USA) "Expedition to Breach the CHNO Ceiling by...Introduction by Discussion Leader 9:15 am - 9:45 am Ryan Austin (Lawrence Livermore National Laboratory, USA) "Investigating the Crystal -Level

Study on penetration-induced initiation of energetic fragment

Science.gov (United States)

Qiao, Xiangxin; Xu, Heyang

2017-09-01

In order to investigate penetration-induced initiation of energetic fragment penetrating target, PTFE/Al (mass ratio 73.5/26.5) pressed and sintered into a Ф8mm × 8mm cylinder. To form energetic fragment, the cylinder was put into a closed container made by 35CrMnSiA. The container is 12mm long, 2mm thick. Energetic fragments were launched by a 14.5mm ballistic gun with a series of velocities and the penetrate process was simulated by AUTODYN-3D. The results show that the stress peak of energetic material exceed the initiation threshold, and energetic material will deflagrate, when energetic fragments impact velocity more than 800 m/s. The research results can provide reference for designs of energetic warhead.

Dynamic fracture and hot-spot modeling in energetic composites

Science.gov (United States)

Grilli, Nicolò; Duarte, Camilo A.; Koslowski, Marisol

2018-02-01

Defects such as cracks, pores, and particle-matrix interface debonding affect the sensitivity of energetic materials by reducing the time-to-ignition and the threshold pressure to initiate an explosion. Frictional sliding of preexisting cracks is considered to be one of the most important causes of localized heating. Therefore, understanding the dynamic fracture of crystalline energetic materials is of extreme importance to assess the reliability and safety of polymer-bonded explosives. Phase field damage model simulations, based on the regularization of the crack surface as a diffuse delta function, are used to describe crack propagation in cyclotetramethylene-tetranitramine crystals embedded in a Sylgard matrix. A thermal transport model that includes heat generation by friction at crack interfaces is coupled to the solution of crack propagation. 2D and 3D dynamic compression simulations are performed with different boundary velocities and initial distributions of cracks and interface defects to understand their effect on crack propagation and heat generation. It is found that, at an impact velocity of 400 m/s, localized damage at the particle-binder interface is of key importance and that the sample reaches temperatures high enough to create a hot-spot that will lead to ignition. At an impact velocity of 10 m/s, preexisting cracks advanced inside the particle, but the increase of temperature will not cause ignition.

Mammalian energetics. Flexible energetics of cheetah hunting strategies provide resistance against kleptoparasitism.

Science.gov (United States)

Scantlebury, David M; Mills, Michael G L; Wilson, Rory P; Wilson, John W; Mills, Margaret E J; Durant, Sarah M; Bennett, Nigel C; Bradford, Peter; Marks, Nikki J; Speakman, John R

2014-10-03

Population viability is driven by individual survival, which in turn depends on individuals balancing energy budgets. As carnivores may function close to maximum sustained power outputs, decreased food availability or increased activity may render some populations energetically vulnerable. Prey theft may compromise energetic budgets of mesopredators, such as cheetahs and wild dogs, which are susceptible to competition from larger carnivores. We show that daily energy expenditure (DEE) of cheetahs was similar to size-based predictions and positively related to distance traveled. Theft at 25% only requires cheetahs to hunt for an extra 1.1 hour per day, increasing DEE by just 12%. Therefore, not all mesopredators are energetically constrained by direct competition. Other factors that increase DEE, such as those that increase travel, may be more important for population viability. Copyright © 2014, American Association for the Advancement of Science.

Watching proteins function with time-resolved x-ray crystallography

Science.gov (United States)

Šrajer, Vukica; Schmidt, Marius

2017-09-01

Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol. 305 115-54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201-41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol. 22 651-9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237-51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5-20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242-6, Barends et al 2015 Science 350 445-50, Pande et al 2016 Science 352 725-9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs. We also outline

A coordinated two-satellite study of energetic electron precipitation events

International Nuclear Information System (INIS)

Imhof, W.L.; Nakano, G.H.; Gaines, E.E.; Reagan, J.B.

1975-01-01

A new technique for studying the spatial/temporal variations of energetic electron precipitation events is investigated. Data are presented in which precipitating electrons were measured simultaneously on two coordinated polar-orbiting satellites and the bremsstrahlung produced by the electrons precipitating into the atmosphere was observed from one of the satellites. Two electron spectrometers measuring the intensities and energy spectra of electrons of >130 keV were located on the oriented satellite 1971-089A (altitude, approx. =800 km), whereas a single similar spectrometer measuring electrons of >160 keV was located on the spinning low-altitude (approx.750 km) satellite 1972-076B. The X rays of >50 keV were measured with a 50-cm 3 germanium spectrometer placed on the 1972-076B satellite. With the coordinated data a study is made of events in which large fluctuations were observed in the precipitating energetic electron intensities. In the examples presented the satellite X ray data alone demonstrate that the spatially integrated electron influx was constant in time, and when the X ray data are combined with the direct electron measurements from the two satellites, the resulting data suggest that the major features in the flux profiles were primarily spatial in nature. The combination of X ray and electron measurements from two satellites is shown to provide an important method for studying and attempting to resolve spatial and temporal effects

Liquid-crystal laser optics: design, fabrication, and performance

International Nuclear Information System (INIS)

Jacobs, S.D.; Cerqua, K.A.; Marshall, K.L.; Schmid, A.; Guardalben, M.J.; Skerrett, K.J.

1988-01-01

We describe the development of laser optics utilizing liquid crystals. Devices discussed constitute passive optical elements for both low-power and high-power laser systems, operating in either the pulsed or cw mode. Designs and fabrication methods are given in detail for wave plates, circular polarizers, optical isolators, laser-blocking notch filters, and soft apertures. Performance data in the visible to near infrared show these devices to be useful alternatives to other technologies based on conventional glasses, crystals, or thin films. The issue of laser damage is examined on the basis of off-line threshold testing and daily use in OMEGA, the 24-beam Nd:glass laser system at the Laboratory for Laser Energetics. Results demonstrate that long-term survivability has been achieved

Vacancy defect and defect cluster energetics in ion-implanted ZnO

Science.gov (United States)

Dong, Yufeng; Tuomisto, F.; Svensson, B. G.; Kuznetsov, A. Yu.; Brillson, Leonard J.

2010-02-01

We have used depth-resolved cathodoluminescence, positron annihilation, and surface photovoltage spectroscopies to determine the energy levels of Zn vacancies and vacancy clusters in bulk ZnO crystals. Doppler broadening-measured transformation of Zn vacancies to vacancy clusters with annealing shifts defect energies significantly lower in the ZnO band gap. Zn and corresponding O vacancy-related depth distributions provide a consistent explanation of depth-dependent resistivity and carrier-concentration changes induced by ion implantation.

A 2D nickel-based energetic MOFs incorporating 3,5-diamino-1,2,4-triazole and malonic acid: Synthesis, crystal structure and thermochemical study

International Nuclear Information System (INIS)

Yang, Qi; Song, Xiaxia; Ge, Jing; Zhao, Guowei; Zhang, Wendou; Xie, Gang; Chen, Sanping; Gao, Shengli

2016-01-01

Highlights: • An energetic MOFs with dinuclear nickel unit has been synthesized and characterized. • The Arrhenius equation, derived from kinetics analysis, is ln k = 55.89 − 332.01 × 10 3 /RT. • The standard molar enthalpy of formation of the compound is determined by a thermochemical cycle. • The molar heat capacity at T = 298.15 K is determined to be 1.42 ± 0.11 J · K −1 · g −1 . - Abstract: A new energetic MOFs, {[Ni 2 (C 2 H 5 N 5 ) 2 (C 3 H 2 O 4 ) 2 (H 2 O)]·3H 2 O} n (Hdatrz (C 2 H 5 N 5 ) = 3,5-diamino-1,2,4-triazole, H 2 mal (C 3 H 4 O 4 ) = malonic acid), has been synthesized and characterized by element analysis, chemical analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analysis confirmed that the compound featured a 2D layer structure with dinuclear Ni(II) unit. Thermal analysis demonstrated that the compound after dehydration have good thermostability with decomposition temperature up to 633 K. The non-isothermal kinetics for the compound was studied by Kissinger’s and Ozawa’s methods. The Arrhenius equation of initial thermal decomposition process of compound can be expressed as ln k = 55.89 − 332.01 × 10 3 /RT. Furthermore, a reasonable thermochemical cycle was designed based on the preparation reaction of the compound, and standard molar enthalpy of dissolution of reactants and products were measured by RD496-2000 calorimeter. Finally, the standard molar enthalpy of formation of the compound was determined to be −(2766.3 ± 2.3) kJ · mol −1 in accordance with Hess’s law. In addition, the specific heat capacity of the compound at T = 298.15 K was determined to be 1.42 ± 0.11 J · K −1 · g −1 by RD496-2000 calorimeter.

Resolved sidebands in a strain-coupled hybrid spin-oscillator system

OpenAIRE

Teissier, Jean; Barfuss, Arne; Appel, Patrick; Neu, Elke; Maletinsky, P.

2014-01-01

We report on single electronic spins coupled to the motion of mechanical resonators by a novel mechanism based on crystal strain. Our device consists of single-crystalline diamond cantilevers with embedded Nitrogen-Vacancy center spins. Using optically detected electron spin resonance, we determine the unknown spin-strain coupling constants and demonstrate that our system resides well within the resolved sideband regime. We realize coupling strengths exceeding ten MHz under mechanical driving...

Strain relaxation of GaAs/Ge crystals on patterned Si substrates

International Nuclear Information System (INIS)

Taboada, A. G.; Kreiliger, T.; Falub, C. V.; Känel, H. von; Isa, F.; Isella, G.; Salvalaglio, M.; Miglio, L.; Wewior, L.; Fuster, D.; Alén, B.; Richter, M.; Uccelli, E.; Niedermann, P.; Neels, A.; Dommann, A.; Mancarella, F.

2014-01-01

We report on the mask-less integration of GaAs crystals several microns in size on patterned Si substrates by metal organic vapor phase epitaxy. The lattice parameter mismatch is bridged by first growing 2-μm-tall intermediate Ge mesas on 8-μm-tall Si pillars by low-energy plasma enhanced chemical vapor deposition. We investigate the morphological evolution of the GaAs crystals towards full pyramids exhibiting energetically stable (111) facets with decreasing Si pillar size. The release of the strain induced by the mismatch of thermal expansion coefficients in the GaAs crystals has been studied by X-ray diffraction and photoluminescence measurements. The strain release mechanism is discussed within the framework of linear elasticity theory by Finite Element Method simulations, based on realistic geometries extracted from scanning electron microscopy images

Strain relaxation of GaAs/Ge crystals on patterned Si substrates

Energy Technology Data Exchange (ETDEWEB)

Taboada, A. G., E-mail: gonzalez@phys.ethz.ch; Kreiliger, T.; Falub, C. V.; Känel, H. von [Laboratory for Solid State Physics, ETH Zürich, Otto-Stern-Weg 1, CH-8093 Zürich (Switzerland); Isa, F.; Isella, G. [L-NESS, Department of Physics, Politecnico di Milano, via Anzani 42, I-22100 Como (Italy); Salvalaglio, M.; Miglio, L. [L-NESS, Department of Materials Science, Università di Milano-Bicocca, via Cozzi 55, I-20125 Milano (Italy); Wewior, L.; Fuster, D.; Alén, B. [IMM, Instituto de Microelectrónica de Madrid (CNM, CSIC), C/Isaac Newton 8, E-28760 Tres Cantos, Madrid (Spain); Richter, M.; Uccelli, E. [Functional Materials Group, IBM Research-Zürich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Niedermann, P.; Neels, A.; Dommann, A. [Centre Suisse d' Electronique et Microtechnique, Jaquet-Droz 1, CH-2002 Neuchatel (Switzerland); Mancarella, F. [CNR-IMM of Bologna, Via Gobetti 101, I-40129 Bologna (Italy)

2014-01-13

We report on the mask-less integration of GaAs crystals several microns in size on patterned Si substrates by metal organic vapor phase epitaxy. The lattice parameter mismatch is bridged by first growing 2-μm-tall intermediate Ge mesas on 8-μm-tall Si pillars by low-energy plasma enhanced chemical vapor deposition. We investigate the morphological evolution of the GaAs crystals towards full pyramids exhibiting energetically stable (111) facets with decreasing Si pillar size. The release of the strain induced by the mismatch of thermal expansion coefficients in the GaAs crystals has been studied by X-ray diffraction and photoluminescence measurements. The strain release mechanism is discussed within the framework of linear elasticity theory by Finite Element Method simulations, based on realistic geometries extracted from scanning electron microscopy images.

Rural energetic development: cuban experience

International Nuclear Information System (INIS)

Aguilera Barciela, M.

1994-01-01

The development of electro energetic national system in Cuba has been directed to the following objectives: to brake the rural population's exodus toward the cities, electrification of dairy farm, interconnection to the system electro energetic of all the sugar central production, these improves the rural population's conditions life

Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser

Energy Technology Data Exchange (ETDEWEB)

Wu, Wenting; Nogly, Przemyslaw; Rheinberger, Jan; Kick, Leonhard M.; Gati, Cornelius; Nelson, Garrett; Deupi, Xavier; Standfuss, Jörg; Schertler, Gebhard; Panneels, Valérie, E-mail: valerie.panneels@psi.ch [Paul Scherrer Institute, OFLC/103, 5232 Villigen-PSI (Switzerland)

2015-06-27

A new batch preparation method is presented for high-density micrometre-sized crystals of the G protein-coupled receptor rhodopsin for use in time-resolved serial femtosecond crystallography at an X-ray free-electron laser using a liquid jet. Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup.

Nitrogen-Rich Energetic Metal-Organic Framework: Synthesis, Structure, Properties, and Thermal Behaviors of Pb(II Complex Based on N,N-Bis(1H-tetrazole-5-yl-Amine

Directory of Open Access Journals (Sweden)

Qiangqiang Liu

2016-08-01

Full Text Available The focus of energetic materials is on searching for a high-energy, high-density, insensitive material. Previous investigations have shown that 3D energetic metal–organic frameworks (E-MOFs have great potential and advantages in this field. A nitrogen-rich E-MOF, Pb(bta·2H2O [N% = 31.98%, H2bta = N,N-Bis(1H-tetrazole-5-yl-amine], was prepared through a one-step hydrothermal reaction in this study. Its crystal structure was determined through single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, and elemental analysis. The complex has high heat denotation (16.142 kJ·cm−3, high density (3.250 g·cm−3, and good thermostability (Tdec = 614.9 K, 5 K·min−1. The detonation pressure and velocity obtained through theoretical calculations were 43.47 GPa and 8.963 km·s−1, respectively. The sensitivity test showed that the complex is an impact-insensitive material (IS > 40 J. The thermal decomposition process and kinetic parameters of the complex were also investigated through thermogravimetry and differential scanning calorimetry. Non-isothermal kinetic parameters were calculated through the methods of Kissinger and Ozawa-Doyle. Results highlighted the nitrogen-rich MOF as a potential energetic material.

The location of energetic compartments affects energetic communication in cardiomyocytes

Directory of Open Access Journals (Sweden)

Rikke eBirkedal

2014-09-01

Full Text Available The heart relies on accurate regulation of mitochondrial energy supply to match energy demand. The main regulators are Ca2+ and feedback of ADP and Pi. Regulation via feedback has intrigued for decades. First, the heart exhibits a remarkable metabolic stability. Second, diffusion of ADP and other molecules is restricted specifically in heart and red muscle, where a fast feedback is needed the most. To explain the regulation by feedback, compartmentalization must be taken into account. Experiments and theoretical approaches suggest that cardiomyocyte energetic compartmentalization is elaborate with barriers obstructing diffusion in the cytosol and at the level of the mitochondrial outer membrane (MOM. A recent study suggests the barriers are organized in a lattice with dimensions in agreement with those of intracellular structures. Here, we discuss the possible location of these barriers. The more plausible scenario includes a barrier at the level of MOM. Much research has focused on how the permeability of MOM itself is regulated, and the importance of the creatine kinase system to facilitate energetic communication. We hypothesize that at least part of the diffusion restriction at the MOM level is not by MOM itself, but due to the close physical association between the sarcoplasmic reticulum (SR and mitochondria. This will explain why animals with a disabled creatine kinase system exhibit rather mild phenotype modifications. Mitochondria are hubs of energetics, but also ROS production and signaling. The close association between SR and mitochondria may form a diffusion barrier to ADP added outside a permeabilised cardiomyocyte. But in vivo, it is the structural basis for the mitochondrial-SR coupling that is crucial for the regulation of mitochondrial Ca2+-transients to regulate energetics, and for avoiding Ca2+-overload and irreversible opening of the mitochondrial permeability transition pore.

Grain Boundaries Act as Solid Walls for Charge Carrier Diffusion in Large Crystal MAPI Thin Films.

Science.gov (United States)

Ciesielski, Richard; Schäfer, Frank; Hartmann, Nicolai F; Giesbrecht, Nadja; Bein, Thomas; Docampo, Pablo; Hartschuh, Achim

2018-03-07

Micro- and nanocrystalline methylammonium lead iodide (MAPI)-based thin-film solar cells today reach power conversion efficiencies of over 20%. We investigate the impact of grain boundaries on charge carrier transport in large crystal MAPI thin films using time-resolved photoluminescence (PL) microscopy and numerical model calculations. Crystal sizes in the range of several tens of micrometers allow for the spatially and time resolved study of boundary effects. Whereas long-ranged diffusive charge carrier transport is observed within single crystals, no detectable diffusive transport occurs across grain boundaries. The observed PL transients are found to crucially depend on the microscopic geometry of the crystal and the point of observation. In particular, spatially restricted diffusion of charge carriers leads to slower PL decay near crystal edges as compared to the crystal center. In contrast to many reports in the literature, our experimental results show no quenching or additional loss channels due to grain boundaries for the studied material, which thus do not negatively affect the performance of the derived thin-film devices.

Interaction Heterogeneity can Favorably Impact Colloidal Crystal Nucleation

Science.gov (United States)

Jenkins, Ian C.; Crocker, John C.; Sinno, Talid

2017-10-01

Colloidal particles with short-ranged attractions, e.g., micron-scale spheres functionalized with single-stranded DNA oligomers, are susceptible to becoming trapped in disordered configurations even when a crystalline arrangement is the ground state. Moreover, for reasons that are not well understood, seemingly minor variations in the particle formulation can lead to dramatic changes in the crystallization outcome. We demonstrate, using a combination of equilibrium and nonequilibrium computer simulations, that interaction heterogeneity—variations in the energetic interactions among different particle pairs in the population—may favorably impact crystal nucleation. Specifically, interaction heterogeneity is found to lower the free energy barrier to nucleation via the formation of clusters comprised preferentially of strong-binding particle pairs. Moreover, gelation is inhibited by "spreading out over time" the nucleation process, resulting in a reduced density of stable nuclei, allowing each to grow unhindered and larger. Our results suggest a simple and robust approach for enhancing colloidal crystallization near the "sticky sphere" limit, and support the notion that differing extents of interaction heterogeneity arising from various particle functionalization protocols may contribute to the otherwise unexplained variations in crystallization outcomes reported in the literature.

Quantum technology past, present, future: quantum energetics (Conference Presentation)

Science.gov (United States)

Choi, Sang H.

2017-04-01

Since the development of quantum physics in the early part of the 1900s, this field of study has made remarkable contributions to our civilization. Some of these advances include lasers, light-emitting diodes (LED), sensors, spectroscopy, quantum dots, quantum gravity and quantum entanglements. In 1998, the NASA Langley Research Center established a quantum technology committee to monitor the progress in this area and initiated research to determine the potential of quantum technology for future NASA missions. The areas of interest in quantum technology at NASA included fundamental quantum-optics materials associated with quantum dots and quantum wells, device-oriented photonic crystals, smart optics, quantum conductors, quantum information and computing, teleportation theorem, and quantum energetics. A brief review of the work performed, the progress made in advancing these technologies, and the potential NASA applications of quantum technology will be presented.

Time-resolved methods in biophysics. 6. Time-resolved Laue crystallography as a tool to investigate photo-activated protein dynamics.

Science.gov (United States)

Bourgeois, Dominique; Schotte, Friedrich; Brunori, Maurizio; Vallone, Beatrice

2007-10-01

When polychromatic X-rays are shined onto crystalline material, they generate a Laue diffraction pattern. At third generation synchrotron radiation sources, a single X-ray pulse of approximately 100 ps duration is enough to produce interpretable Laue data from biomolecular crystals. Thus, by initiating biological turnover in a crystalline protein, structural changes along the reaction pathway may be filmed by ultra-fast Laue diffraction. Using laser-light as a trigger, transient species in photosensitive macromolecules can be captured at near atomic resolution with sub-nanosecond time-resolution. Such pump-probe Laue experiments have now reached an outstanding level of sophistication and have found a domain of excellence in the investigation of light-sensitive proteins undergoing cyclic photo-reactions and producing stiff crystals. The main theoretical concepts of Laue diffraction and the challenges associated with time-resolved experiments on biological crystals are recalled. The recent advances in the design of experiments are presented in terms of instrumental choices, data collection strategy and data processing, and some of the inherent difficulties of the method are highlighted. The discussion is based on the example of myoglobin, a protein that has traversed the whole history of pump-probe Laue diffraction, and for which a massive amount of data have provided considerable insight into the understanding of protein dynamics.

The Principle of Energetic Consistency

Science.gov (United States)

Cohn, Stephen E.

2009-01-01

A basic result in estimation theory is that the minimum variance estimate of the dynamical state, given the observations, is the conditional mean estimate. This result holds independently of the specifics of any dynamical or observation nonlinearity or stochasticity, requiring only that the probability density function of the state, conditioned on the observations, has two moments. For nonlinear dynamics that conserve a total energy, this general result implies the principle of energetic consistency: if the dynamical variables are taken to be the natural energy variables, then the sum of the total energy of the conditional mean and the trace of the conditional covariance matrix (the total variance) is constant between observations. Ensemble Kalman filtering methods are designed to approximate the evolution of the conditional mean and covariance matrix. For them the principle of energetic consistency holds independently of ensemble size, even with covariance localization. However, full Kalman filter experiments with advection dynamics have shown that a small amount of numerical dissipation can cause a large, state-dependent loss of total variance, to the detriment of filter performance. The principle of energetic consistency offers a simple way to test whether this spurious loss of variance limits ensemble filter performance in full-blown applications. The classical second-moment closure (third-moment discard) equations also satisfy the principle of energetic consistency, independently of the rank of the conditional covariance matrix. Low-rank approximation of these equations offers an energetically consistent, computationally viable alternative to ensemble filtering. Current formulations of long-window, weak-constraint, four-dimensional variational methods are designed to approximate the conditional mode rather than the conditional mean. Thus they neglect the nonlinear bias term in the second-moment closure equation for the conditional mean. The principle of

Second School of Nuclear Energetics

International Nuclear Information System (INIS)

2009-01-01

At 3-5 Nov 2009 Institute of Nuclear Energy POLATOM, Association of Polish Electrical Engineers (SEP) and Polish Nuclear Society have organized Second School of Nuclear Energetics. 165 participants have arrived from all Poland and represented both different central institutions (e.g. ministries) and local institutions (e.g. Office of Technical Inspection, The Voivodship Presidential Offices, several societies, consulting firms or energetic enterprises). Students from the Warsaw Technical University and Gdansk Technical University, as well as the PhD students from the Institute of Nuclear Chemistry and Technology (Warsaw) attended the School. 20 invited lectures presented by eminent Polish specialists concerned basic problems of nuclear energetics, nuclear fuel cycle and different problems of the NPP construction in Poland. [pl

New Generation Agent Defeat Weapons: Energetic N,N'-Ethylene-Bridged Polyiodoazoles.

Science.gov (United States)

Zhao, Gang; Kumar, Dheeraj; He, Chunlin; Hooper, Joseph P; Imler, Gregory H; Parrish, Damon A; Shreeve, Jean'ne M

2017-11-27

Sodium salts of iodine-rich pyrazole and imidazole with 1-(2-bromoethyl)-5-aminotetrazole are useful precursors for energetic N,N'-ethylene-bridged polyiodoazoles. Compounds 1-3 were characterized with IR, and 1 H and 13 C NMR spectroscopy as well as elemental analyses. The molecular structures of 1 and 2 were confirmed by using single crystal X-ray diffraction. Heats of formation were calculated using Gaussian 03 and detonation properties and biocidal efficiency were calculated with CHEETAH 7. The decomposition products of 1-3 destroy microbes more effectively than some previously reported biocides since the thermal decomposition occurs at below 400 °C without addition of oxidizer or combustion adjuvant. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Duty-cycle and energetics of remnant radio-loud AGN

Science.gov (United States)

Turner, Ross J.

2018-05-01

Deriving the energetics of remnant and restarted active galactic nuclei (AGNs) is much more challenging than for active sources due to the complexity in accurately determining the time since the nucleus switched-off. I resolve this problem using a new approach that combines spectral ageing and dynamical models to tightly constrain the energetics and duty-cycles of dying sources. Fitting the shape of the integrated radio spectrum yields the fraction of the source age the nucleus is active; this, in addition to the flux density, source size, axis ratio, and properties of the host environment, provides a constraint on dynamical models describing the remnant radio source. This technique is used to derive the intrinsic properties of the well-studied remnant radio source B2 0924+30. This object is found to spend 50_{-12}^{+14} Myr in the active phase and a further 28_{-5}^{+6} Myr in the quiescent phase, have a jet kinetic power of 3.6_{-1.7}^{+3.0}× 10^{37} W, and a lobe magnetic field strength below equipartition at the 8σ level. The integrated spectra of restarted and intermittent radio sources are found to yield a `steep-shallow' shape when the previous outburst occurred within 100 Myr. The duty-cycle of B2 0924+30 is hence constrained to be δ < 0.15 by fitting the shortest time to the previous comparable outburst that does not appreciably modify the remnant spectrum. The time-averaged feedback energy imparted by AGNs into their host galaxy environments can in this manner be quantified.

Energetic map

International Nuclear Information System (INIS)

2012-01-01

This report explains the energetic map of Uruguay as well as the different systems that delimits political frontiers in the region. The electrical system importance is due to the electricity, oil and derived , natural gas, potential study, biofuels, wind and solar energy

Angle-resolved effective potentials for disk-shaped molecules

Energy Technology Data Exchange (ETDEWEB)

Heinemann, Thomas, E-mail: thomas.heinemann@tu-berlin.de; Klapp, Sabine H. L., E-mail: klapp@physik.tu-berlin.de [Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Palczynski, Karol, E-mail: karol.palczynski@helmholtz-berlin.de; Dzubiella, Joachim, E-mail: joachim.dzubiella@helmholtz-berlin.de [Institut für Physik, Humboldt Universität zu Berlin, Newtonstraße 15, 12489 Berlin (Germany); Helmholtz Zentrum Berlin (HZB), Institute of Soft Matter and Functional Materials, Hahn-Meitner Platz 1, 14109 Berlin (Germany)

2014-12-07

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.

Angle-resolved diffraction grating biosensor based on porous silicon

Energy Technology Data Exchange (ETDEWEB)

Lv, Changwu; Li, Peng [School of Physical Science and Technology, Xinjiang University, Urumqi 830046 (China); Jia, Zhenhong, E-mail: jzhh@xju.edu.cn; Liu, Yajun; Mo, Jiaqing; Lv, Xiaoyi [College of Information Science and Engineering, Xinjiang University, Urumqi 830046 (China)

2016-03-07

In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

Economical aspects of nuclear energetics

International Nuclear Information System (INIS)

Celinski, Z.

2000-01-01

The economical aspects of nuclear power generation in respect to costs of conventional energetics have been discussed in detail. The costs and competitiveness of nuclear power have been considered on the base of worldwide trends taking into account investment and fuel costs as well as 'social' costs being result of impact of different types of energetics on environment, human health etc

Signature of crystal symmetry in positron annihilation data

International Nuclear Information System (INIS)

Adam, G.; Adam, S.

1994-12-01

While the technique of two-dimensional angular correlation of the electron-positron annihilation radiation (2D-ACAR) yields data in a reference frame related to detectors, data interpretation is made in a reference frame related to the crystal. The paper shows that consistent reformulation of the 2D-ACAR data in the crystal frame can be obtained from the knowledge of the signature of crystal symmetry (SCS) in the data. Derivation of the SCS over variations M-Umklapp areas of the reciprocal lattice from a rigorous definition also results in an improved a posteriori criterion concerning the twinned or untwinned nature of the crystal under investigation. The analysis of a c-projected 2D-ACAR spectrum on Y Ba 2 Cu 3 O 7-δ , accurately establishes the untwinned nature of the used crystals and yields better resolved Fermi surface ridge signatures at 2- and 3- Umklapp processes. (author). 32 refs, 4 figs, 2 tabs

Space resolved x-ray diffraction measurements of the supercooled state of polymers

International Nuclear Information System (INIS)

Asano, Tsutomu; Yoshida, Shinya; Nishida, Akira; Mina, M.F.

2002-01-01

In order to measure an ordering process of polymers, the supercooled state near the crystallizing surface was observed by a space resolved X-ray diffraction method at Photon Factory (PF). Using temperature slope crystallization, low density polyethylene and even-number paraffins were examined during crystallization from the melt state. The results indicate that polyethylene shows a sharp b-axis orientation where the lamellar normal and crystalline c-axis are perpendicular to the temperature slope. The crystalline lamellae are well-developed with lamellar thickness of 180 A. The supercooled melt state just above the crystallizing plane shows some diffraction in the small angle region without any crystalline reflection in the wide angle. This fact suggests that a long-range ordering (lamellar structure) appears prior to the short-range one (crystalline structure). The in-situ crystallizing surface was observed by an optical microscope connected to a TV system. The crystallizing surface of even-number paraffins moves to upwards in the temperature slope. In-situ X-ray measurements at PF revealed that the crystalline c-axis and lamellar normal of the even number paraffins are parallel to the temperature slope. From these results, the crystalline ordering and the surface movement of even number paraffins are explained using special nucleation mechanism including a screw dislocation. (author)

Energetic Sustainability and the Environment: A Transdisciplinary, Economic–Ecological Approach

Directory of Open Access Journals (Sweden)

Ioan G. Pop

2017-05-01

Full Text Available The paper combines original concepts about eco-energetic systems, in a transdisciplinary sustainable context. Firstly, it introduces the concept of M.E.N. (Mega-Eco-Nega-Watt, the eco-energetic paradigm based on three different but complementary ecological economic spaces: the Megawatt as needed energy, the Ecowatt as ecological energy, and the Negawatt as preserved energy. The paper also deals with the renewable energies and technologies in the context of electrical energy production. Secondly, in the context of the M.E.N. eco-energetic paradigm, comprehensive definitions are given about eco-energetic systems and for pollution. Thirdly, the paper introduces a new formula for the eco-energetic efficiency which correlates the energetic efficiency of the system and the necessary newly defined ecological coefficient. The proposed formula for eco-energetic efficiency enables an interesting form of relating to different situations in which the input energy, output energy, lost energy, and externalities involved in an energetic process, interact to produce energy in a specific energetic system, in connection with the circular resilient economy model. Finally, the paper presents an original energetic diagram to explain different channels to produce electricity in a resilience regime, with high eco-energetic efficiency from primary external energetic sources (gravitation and solar sources, fuels (classical and radioactive, internal energetic sources (geothermal, volcanoes and other kind of sources. Regardless the kind of energetic sources used to obtain electricity, the entire process should be sustainable in what concerns the transdisciplinary integration of the different representative spheres as energy, socio-economy, and ecology (environment.

Watching proteins function with time-resolved x-ray crystallography

Energy Technology Data Exchange (ETDEWEB)

Šrajer, Vukica; Schmidt, Marius

2017-08-22

Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol. 305 115–54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201–41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol. 22 651–9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237–51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5–20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242–6, Barends et al 2015 Science 350 445–50, Pande et al 2016 Science 352 725–9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs. We

Watching proteins function with time-resolved x-ray crystallography

International Nuclear Information System (INIS)

Šrajer, Vukica; Schmidt, Marius

2017-01-01

Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol . 305 115–54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201–41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol . 22 651–9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237–51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5–20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242–6, Barends et al 2015 Science 350 445–50, Pande et al 2016 Science 352 725–9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs

Energetic and Spatial Bonding Properties from Angular Distributions of Ultraviolet Photoelectrons: Application to the GaAs(110) Surface

International Nuclear Information System (INIS)

Fadley, C.S.; Fadley, C.S.; Van Hove, M.A.

1997-01-01

Angle-resolved ultraviolet photoemission spectra are interpreted by combining the energetics and spatial properties of the contributing states. One-step calculations are in excellent agreement with new azimuthal experimental data for GaAs(110). Strong variations caused by the dispersion of the surface bands permit an accurate mapping of the electronic structure. The delocalization of the valence states is discussed analogous to photoelectron diffraction. The spatial origin of the electrons is determined, and found to be strongly energy dependent, with uv excitation probing the bonding region. copyright 1997 The American Physical Society

A simple approach to spectrally resolved fluorescence and bright field microscopy over select regions of interest.

Science.gov (United States)

Dahlberg, Peter D; Boughter, Christopher T; Faruk, Nabil F; Hong, Lu; Koh, Young Hoon; Reyer, Matthew A; Shaiber, Alon; Sherani, Aiman; Zhang, Jiacheng; Jureller, Justin E; Hammond, Adam T

2016-11-01

A standard wide field inverted microscope was converted to a spatially selective spectrally resolved microscope through the addition of a polarizing beam splitter, a pair of polarizers, an amplitude-mode liquid crystal-spatial light modulator, and a USB spectrometer. The instrument is capable of simultaneously imaging and acquiring spectra over user defined regions of interest. The microscope can also be operated in a bright-field mode to acquire absorption spectra of micron scale objects. The utility of the instrument is demonstrated on three different samples. First, the instrument is used to resolve three differently labeled fluorescent beads in vitro. Second, the instrument is used to recover time dependent bleaching dynamics that have distinct spectral changes in the cyanobacteria, Synechococcus leopoliensis UTEX 625. Lastly, the technique is used to acquire the absorption spectra of CH 3 NH 3 PbBr 3 perovskites and measure differences between nanocrystal films and micron scale crystals.

A simple approach to spectrally resolved fluorescence and bright field microscopy over select regions of interest

Science.gov (United States)

Dahlberg, Peter D.; Boughter, Christopher T.; Faruk, Nabil F.; Hong, Lu; Koh, Young Hoon; Reyer, Matthew A.; Shaiber, Alon; Sherani, Aiman; Zhang, Jiacheng; Jureller, Justin E.; Hammond, Adam T.

2016-11-01

A standard wide field inverted microscope was converted to a spatially selective spectrally resolved microscope through the addition of a polarizing beam splitter, a pair of polarizers, an amplitude-mode liquid crystal-spatial light modulator, and a USB spectrometer. The instrument is capable of simultaneously imaging and acquiring spectra over user defined regions of interest. The microscope can also be operated in a bright-field mode to acquire absorption spectra of micron scale objects. The utility of the instrument is demonstrated on three different samples. First, the instrument is used to resolve three differently labeled fluorescent beads in vitro. Second, the instrument is used to recover time dependent bleaching dynamics that have distinct spectral changes in the cyanobacteria, Synechococcus leopoliensis UTEX 625. Lastly, the technique is used to acquire the absorption spectra of CH3NH3PbBr3 perovskites and measure differences between nanocrystal films and micron scale crystals.

Safer energetic materials by a nanotechnological approach

Science.gov (United States)

Siegert, Benny; Comet, Marc; Spitzer, Denis

2011-09-01

Energetic materials - explosives, thermites, populsive powders - are used in a variety of military and civilian applications. Their mechanical and electrostatic sensitivity is high in many cases, which can lead to accidents during handling and transport. These considerations limit the practical use of some energetic materials despite their good performance. For industrial applications, safety is one of the main criteria for selecting energetic materials. The sensitivity has been regarded as an intrinsic property of a substance for a long time. However, in recent years, several approaches to lower the sensitivity of a given substance, using nanotechnology and materials engineering, have been described. This feature article gives an overview over ways to prepare energetic (nano-)materials with a lower sensitivity.Energetic materials - explosives, thermites, populsive powders - are used in a variety of military and civilian applications. Their mechanical and electrostatic sensitivity is high in many cases, which can lead to accidents during handling and transport. These considerations limit the practical use of some energetic materials despite their good performance. For industrial applications, safety is one of the main criteria for selecting energetic materials. The sensitivity has been regarded as an intrinsic property of a substance for a long time. However, in recent years, several approaches to lower the sensitivity of a given substance, using nanotechnology and materials engineering, have been described. This feature article gives an overview over ways to prepare energetic (nano-)materials with a lower sensitivity. Electronic supplementary information (ESI) available: Experimental details for the preparation of the V2O5@CNF/Al nanothermite; X-ray diffractogram of the V2O5@CNF/Al combustion residue; installation instructions and source code for the nt-timeline program. See DOI: 10.1039/c1nr10292c

Neurosurgery contact handheld probe based on sapphire shaped crystal

Science.gov (United States)

Shikunova, I. A.; Stryukov, D. O.; Rossolenko, S. N.; Kiselev, A. M.; Kurlov, V. N.

2017-01-01

A handheld contact probe based on sapphire shaped crystal is developed for intraoperative spectrally-resolved optical diagnostics, laser coagulation and aspiration of malignant brain tissue. The technology was integrated into the neurosurgical workflow for intraoperative real-time identification and removing of invasive brain cancer.

Optimization of some eco-energetic systems

International Nuclear Information System (INIS)

Purica, I.; Pavelescu, M.; Stoica, M.

1976-01-01

An optimization problem of two eco-energetic systems is described. The first one is close to the actual eco-energetic system in Romania, while the second is a new one, based on nuclear energy as primary source and hydrogen energy as secondary source. The optimization problem solved is to find the optimal structure of the systems so that the objective functions adopted, namely unitary energy cost C and total pollution P, to be minimum at the same time. The problem can be modelated with a bimatrix cooperative mathematical game without side payments. We demonstrate the superiority of the new eco-energetic system. (author)

Two types of amorphous protein particles facilitate crystal nucleation.

Science.gov (United States)

Yamazaki, Tomoya; Kimura, Yuki; Vekilov, Peter G; Furukawa, Erika; Shirai, Manabu; Matsumoto, Hiroaki; Van Driessche, Alexander E S; Tsukamoto, Katsuo

2017-02-28

Nucleation, the primary step in crystallization, dictates the number of crystals, the distribution of their sizes, the polymorph selection, and other crucial properties of the crystal population. We used time-resolved liquid-cell transmission electron microscopy (TEM) to perform an in situ examination of the nucleation of lysozyme crystals. Our TEM images revealed that mesoscopic clusters, which are similar to those previously assumed to consist of a dense liquid and serve as nucleation precursors, are actually amorphous solid particles (ASPs) and act only as heterogeneous nucleation sites. Crystalline phases never form inside them. We demonstrate that a crystal appears within a noncrystalline particle assembling lysozyme on an ASP or a container wall, highlighting the role of heterogeneous nucleation. These findings represent a significant departure from the existing formulation of the two-step nucleation mechanism while reaffirming the role of noncrystalline particles. The insights gained may have significant implications in areas that rely on the production of protein crystals, such as structural biology, pharmacy, and biophysics, and for the fundamental understanding of crystallization mechanisms.

Dosimetry for Crystals Irradiation

CERN Document Server

Lecomte, Pierre

2005-01-01

Before shipment to CMS, all PbWO4 crystals produced in China are irradiated there with 60 Co , in order to insure that the induced absorption coefficient is within specifications. Acceptance tests at CERNand at ENEA also include irradiation with gamma rays from 60 Co sources. There were initially discrepancies in quoted doses and doserates as well as in induced absorption coefficients. The present work resolves the discrepancies in irradiation measurements and defines common dosimetry methods for consistency checks between irradiation facilities.

Energetics Laboratory Facilities

Data.gov (United States)

Federal Laboratory Consortium — These energetic materials laboratories are equipped with explosion proof hoods with blow out walls for added safety, that are certified for safe handling of primary...

Fine structure of fields in 2D photonic crystal waveguides

DEFF Research Database (Denmark)

Lavrinenko, Andrei; Volkov, V. S.; Bozhevolnyi, S. I.

2006-01-01

We resolve fine structure of fields in a single-row missing photonic crystal waveguide by finite-difference time-domain modelling and SNOM measurements. Both linear dispersion and slow-light regimes in proximity of the cutoff are addressed in the analysis....

Modeling of the effect of intentionally introduced traps on hole transport in single-crystal rubrene

KAUST Repository

Dacuñ a, Javier; Desai, Amit; Xie, Wei; Salleo, Alberto

2014-01-01

Defects have been intentionally introduced in a rubrene single crystal by means of two different mechanisms: ultraviolet ozone (UVO) exposure and x-ray irradiation. A complete drift-diffusion model based on the mobility edge (ME) concept, which takes into account asymmetries and nonuniformities in the semiconductor, is used to estimate the energetic and spatial distribution of trap states. The trap distribution for pristine devices can be decomposed into two well defined regions: a shallow region ascribed to structural disorder and a deeper region ascribed to defects. UVO and x ray increase the hole trap concentration in the semiconductor with different energetic and spatial signatures. The former creates traps near the top surface in the 0.3-0.4 eV region, while the latter induces a wider distribution of traps extending from the band edge with a spatial distribution that peaks near the top and bottom interfaces. In addition to inducing hole trap states in the transport gap, both processes are shown to reduce the mobility with respect to a pristine crystal. © 2014 American Physical Society.

Modeling of the effect of intentionally introduced traps on hole transport in single-crystal rubrene

KAUST Repository

Dacuña, Javier

2014-06-05

Defects have been intentionally introduced in a rubrene single crystal by means of two different mechanisms: ultraviolet ozone (UVO) exposure and x-ray irradiation. A complete drift-diffusion model based on the mobility edge (ME) concept, which takes into account asymmetries and nonuniformities in the semiconductor, is used to estimate the energetic and spatial distribution of trap states. The trap distribution for pristine devices can be decomposed into two well defined regions: a shallow region ascribed to structural disorder and a deeper region ascribed to defects. UVO and x ray increase the hole trap concentration in the semiconductor with different energetic and spatial signatures. The former creates traps near the top surface in the 0.3-0.4 eV region, while the latter induces a wider distribution of traps extending from the band edge with a spatial distribution that peaks near the top and bottom interfaces. In addition to inducing hole trap states in the transport gap, both processes are shown to reduce the mobility with respect to a pristine crystal. © 2014 American Physical Society.

Crystallization Kinetics of GeSbTe Phase-Change Nanoparticles Resolved by Ultrafast Calorimetry

NARCIS (Netherlands)

Chen, Bin; Brink, ten Gert; Palasantzas, Georgios; Kooi, Bart J.

2017-01-01

Although nanostructured phase-change materials (PCMs) are considered as the building blocks of next-generation phase-change memory and other emerging optoelectronic applications, the kinetics of the crystallization, the central property in switching, remains ambiguous in the high-temperature regime.

Steady-state and time-resolved spectroscopic investigations on intramolecular electron transfer processes within a synthesized methoxynaphthalene dyad by using a nematic liquid crystal medium

International Nuclear Information System (INIS)

Bardhan, Munmun; Mandal, Paulami; De, Asish; Kumar De, Avijit; Chowdhury, Joydeep; Ganguly, Tapan

2010-01-01

UV-vis, steady state and time-resolved spectroscopic investigations were made on photoinduced charge separation and thermal charge recombination processes involved within a novel synthesized dyad, 1-(4-chloro-phenyl)-3-(4-methoxy-naphthalen-1-yl)-propenone (MNCA) where the donor 1-methoxynaphthalene (MNT) and the acceptor p-choloroacetophenone (PCA) moieties are connected by a short unsaturated olefinic bond. The measurements were made within the pseudo-ordered domain (just above nematic-isotropic (N-I) phase transition temperature, >308 K) of a nematic liquid crystal, 4-(n-pentyl)-4'-cyanobiphenyl (5CB). Results observed are compared with those obtained from the similar measurements in isotropic media. The charge separation and recombination rates remain more-or-less unchanged within the experimental error irrespective of the polarity of the environment, whether in pseudo-ordered domain (ε S ∼10.5) of a nematic liquid crystal 5CB or in highly polar isotropic medium ACN (ε S ∼37.5). The structural rigidity of the dyad MNCA having stable elongated form both in the ground as well as in the photoexcited states seems to be the reason for this unique behavior of solvent insensitivity. The theoretical predictions done by ab initio method density functional theory (DFT) with B3LYP/6-311 G (d, p) basis function correlate well with experimental observations of formations of only one stable elongated (E-type) conformer both in the ground and electronic excited state.

Steady-state and time-resolved spectroscopic investigations on intramolecular electron transfer processes within a synthesized methoxynaphthalene dyad by using a nematic liquid crystal medium

Energy Technology Data Exchange (ETDEWEB)

Bardhan, Munmun; Mandal, Paulami; De, Asish; Kumar De, Avijit [Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal (India); Chowdhury, Joydeep [Sammilani Mahavidyalaya Baghajatin Station, West Bengal (India); Ganguly, Tapan, E-mail: sptg@mahendra.iacs.res.i [Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal (India)

2010-06-15

UV-vis, steady state and time-resolved spectroscopic investigations were made on photoinduced charge separation and thermal charge recombination processes involved within a novel synthesized dyad, 1-(4-chloro-phenyl)-3-(4-methoxy-naphthalen-1-yl)-propenone (MNCA) where the donor 1-methoxynaphthalene (MNT) and the acceptor p-choloroacetophenone (PCA) moieties are connected by a short unsaturated olefinic bond. The measurements were made within the pseudo-ordered domain (just above nematic-isotropic (N-I) phase transition temperature, >308 K) of a nematic liquid crystal, 4-(n-pentyl)-4'-cyanobiphenyl (5CB). Results observed are compared with those obtained from the similar measurements in isotropic media. The charge separation and recombination rates remain more-or-less unchanged within the experimental error irrespective of the polarity of the environment, whether in pseudo-ordered domain (epsilon{sub S}approx10.5) of a nematic liquid crystal 5CB or in highly polar isotropic medium ACN (epsilon{sub S}approx37.5). The structural rigidity of the dyad MNCA having stable elongated form both in the ground as well as in the photoexcited states seems to be the reason for this unique behavior of solvent insensitivity. The theoretical predictions done by ab initio method density functional theory (DFT) with B3LYP/6-311 G (d, p) basis function correlate well with experimental observations of formations of only one stable elongated (E-type) conformer both in the ground and electronic excited state.

Crystal diffraction lens for medical imaging

International Nuclear Information System (INIS)

Smither, R. K.; Roa, D. E.

2000-01-01

A crystal diffraction lens for focusing energetic gamma rays has been developed at Argonne National Laboratory for use in medical imaging of radioactivity in the human body. A common method for locating possible cancerous growths in the body is to inject radioactivity into the blood stream of the patient and then look for any concentration of radioactivity that could be associated with the fast growing cancer cells. Often there are borderline indications of possible cancers that could be due to statistical functions in the measured counting rates. In order to determine if these indications are false or real, one must resort to surgical means and take tissue samples in the suspect area. They are developing a system of crystal diffraction lenses that will be incorporated into a 3-D imaging system with better sensitivity (factors of 10 to 100) and better spatial resolution (a few mm in both vertical and horizontal directions) than most systems presently in use. The use of this new imaging system will allow one to eliminate 90% of the false indications and both locate and determine the size of the cancer with mm precision. The lens consists of 900 single crystals of copper, 4 mm x 4 mm on a side and 2--4 mm thick, mounted in 13 concentric rings

1-Amine-1,2,3-triazolium salts with oxidizing anions: A new family of energetic materials with good performance

Science.gov (United States)

Zhang, Zhi-Bin; Zhang, Jian-Guo

2018-04-01

A series of 1-amino-1,2,3-triazole (ATZ) based energetic nitrogen-rich salts are prepared by using acid-base neutralization reaction (1:1 M ratio), and fully characterized. Structures of the salts are recrystallized and determined by single-crystal X-ray diffraction, which dominated by a strong hydrogen-bond influence with the densities ranging from 1.692 to 1.868 g cm-3. Thermal behaviors have characterized by using the DSC and TG-DTG technologies. The enthalpies of formation have calculated by using Gaussian 03. The detonation parameters of the salts are determined by using the K-J method, and most salts show promising detonation performances (D: 6699-8231 m s-1, P: 19.2-30.7 GPa), among which the salt of 1-amino-1,2,3-triazolium trinitrophloroglucinate has a detonation properties comparable to RDX. The sensitivities results provided the salts as insensitive energetic materials.

Difference structures from time-resolved small-angle and wide-angle x-ray scattering

Science.gov (United States)

Nepal, Prakash; Saldin, D. K.

2018-05-01

Time-resolved small-angle x-ray scattering/wide-angle x-ray scattering (SAXS/WAXS) is capable of recovering difference structures directly from difference SAXS/WAXS curves. It does so by means of the theory described here because the structural changes in pump-probe detection in a typical time-resolved experiment are generally small enough to be confined to a single residue or group in close proximity which is identified by a method akin to the difference Fourier method of time-resolved crystallography. If it is assumed, as is usual with time-resolved structures, that the moved atoms lie within the residue, the 100-fold reduction in the search space (assuming a typical protein has about 100 residues) allows the exaction of the structure by a simulated annealing algorithm with a huge reduction in computing time and leads to a greater resolution by varying the positions of atoms only within that residue. This reduction in the number of potential moved atoms allows us to identify the actual motions of the individual atoms. In the case of a crystal, time-resolved calculations are normally performed using the difference Fourier method, which is, of course, not directly applicable to SAXS/WAXS. The method developed in this paper may be thought of as a substitute for that method which allows SAXS/WAXS (and hence disordered molecules) to also be used for time-resolved structural work.

Continuous wave ultraviolet radiation induced frustration of etching in lithium niobate single crystals

Energy Technology Data Exchange (ETDEWEB)

Mailis, S.; Riziotis, C.; Smith, P.G.R.; Scott, J.G.; Eason, R.W

2003-02-15

Illumination of the -z face of congruent lithium niobate single crystals with continuous wave (c.w.) ultraviolet (UV) laser radiation modifies the response of the surface to subsequent acid etching. A frequency doubled Ar{sup +} laser ({lambda}=244 nm) was used to illuminate the -z crystal face making it resistive to HF etching and thus transforming the illuminated tracks into ridge structures. This process enables the fabrication of relief patterns in a photolithographic manner. Spatially resolved Raman spectroscopy indicates preservation of the good crystal quality after irradiation.

Rocket measurements of energetic particles in the midlatitude precipitation zone

Science.gov (United States)

Voss, H. D.; Smith, L. G.; Braswell, F. M.

1980-01-01

Measurements of energetic ion and electron properties as a function of altitude in the midlatitude zone of nighttime energetic particle precipitation are reported. The measurements of particle fluxes, energy spectra and pitch angle distributions were obtained by a Langmuir probe, six energetic particle spectrometers and an electrostatic analyzer on board a Nike Apache rocket launched near the center of the midlatitude zone during disturbed conditions. It is found that the incident flux was primarily absorbed rather than backscattered, and consists of mainly energetic hydrogen together with some helium and a small energetic electron component. Observed differential energy spectra of protons having an exponential energy spectrum, and pitch angle distributions at various altitudes indicate that the energetic particle flux decreases rapidly for pitch angles less than 70 deg. An energetic particle energy flux of 0.002 ergs/sq cm per sec is calculated which indicates the significance of energetic particles as a primary nighttime ionization source for altitudes between 120 and 200 km in the midlatitude precipitation zone.

Terahertz spectroscopic analysis of crystal orientation in polymers

Science.gov (United States)

Azeyanagi, Chisato; Kaneko, Takuya; Ohki, Yoshimichi

2018-05-01

Terahertz time-domain spectroscopy (THz-TDS) is attracting keen attention as a new spectroscopic tool for characterizing various materials. In this research, the possibility of analyzing the crystal orientation in a crystalline polymer by THz-TDS is investigated by measuring angle-resolved THz absorption spectra for sheets of poly(ethylene terephthalate), poly(ethylene naphthalate), and poly(phenylene sulfide). The resultant angle dependence of the absorption intensity of each polymer is similar to that of the crystal orientation examined using pole figures of X-ray diffraction. More specifically, THz-TDS can indicate the alignment of molecules in polymers.

Experimental realization of highly efficient broadband coupling of single quantum dots to a photonic crystal waveguide

DEFF Research Database (Denmark)

Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian

2008-01-01

We present time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides. Quantum dots that couple to a photonic crystal waveguide are found to decay up to 27 times faster than uncoupled quantum dots. From these measurements -factors of up to 0.89 ...... taking into account that the light-matter coupling is strongly enhanced due to the significant slow-down of light in the photonic crystal waveguides....

Polymorphic crystallization of metal-metalloid-glasses above the glass transition temperature

International Nuclear Information System (INIS)

Koster, U.; Schunemann, U.; Stephenson, G.B.; Brauer, S.; Sutton, M.

1992-01-01

Crystallization of metal-metalloid glasses is known to proceed by nucleation and growth processes. Using crystallization statistics in partially crystallized glasses, at temperatures below the glass transition temperature, time-dependent heterogeneous nucleation has been found to occur at a number of quenched-in nucleation sites. Close to the glass transition temperature crystallization proceeds so rapidly that partially crystallized microstructures could not be obtained. Initial results form fully crystallized glasses exhibit evidence for a transient homogeneous nucleation process at higher temperatures. These conclusions are derived post mortem. At there may be some change of the microstructure after crystallization is finished or during he subsequent quenching, it is desirable to directly obtain information during the early stages of crystallization. Recently reported work by Sutton et al. showed that structural changes can be observed in situ during crystallization by time-resolved x-ray diffraction on time scales as short as milliseconds. The aim o the paper is to present the authors study of the crystallization behavior at temperatures near the glass transition by in-situ x-ray diffraction studies and by microstructural analysis after rapid heating experiments. The results are compared to those derived from a computer model of the crystallization process

Continuous API-crystal coating via coacervation in a tubular reactor.

Science.gov (United States)

Besenhard, M O; Thurnberger, A; Hohl, R; Faulhammer, E; Rattenberger, J; Khinast, J G

2014-11-20

We present a proof-of-concept study of a continuous coating process of single API crystals in a tubular reactor using coacervation as a microencapsulation technique. Continuous API crystal coating can have several advantages, as in a single step (following crystallization) individual crystals can be prepared with a functional coating, either to change the release behavior, to protect the API from gastric juice or to modify the surface energetics of the API (i.e., to tailor the hydrophobic/hydrophilic characteristics, flowability or agglomeration tendency, etc.). The coating process was developed for the microencapsulation of a lipophilic core material (ibuprofen crystals of 20 μm- to 100 μm-size), with either hypromellose phthalate (HPMCP) or Eudragit L100-55. The core material was suspended in an aqueous solution containing one of these enteric polymers, fed into the tubing and mixed continuously with a sodium sulfate solution as an antisolvent to induce coacervation. A subsequent temperature treatment was applied to optimize the microencapsulation of crystals via the polymer-rich coacervate phase. Cross-linking of the coating shell was achieved by mixing the processed material with an acidic solution (pH<3). Flow rates, temperature profiles and polymer-to-antisolvent ratios had to be tightly controlled to avoid excessive aggregation, leading to pipe plugging. This work demonstrates the potential of a tubular reactor design for continuous coating applications and is the basis for future work, combining continuous crystallization and coating. Copyright © 2014 Elsevier B.V. All rights reserved.

Deuteron NMR resolved mesogen vs. crosslinker molecular order and reorientational exchange in liquid single crystal elastomers

Czech Academy of Sciences Publication Activity Database

Milavec, J.; Domenici, V.; Zupančič, B.; Rešetič, A.; Bubnov, Alexej; Zalar, B.

2016-01-01

Roč. 18, č. 5 (2016), s. 4071-4077 ISSN 1463-9076 R&D Projects: GA ČR GA15-02843S; GA MŠk(CZ) LD14007 Grant - others:EU - ICT(XE) COST Action IC1208 Institutional support: RVO:68378271 Keywords : liquid single crystal elastomer * NMR * liquid crystal * molecular order * monomers Subject RIV: JJ - Other Materials Impact factor: 4.123, year: 2016

Structure of Energetic Particle Mediated Shocks Revisited

International Nuclear Information System (INIS)

Mostafavi, P.; Zank, G. P.; Webb, G. M.

2017-01-01

The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

Structure of Energetic Particle Mediated Shocks Revisited

Energy Technology Data Exchange (ETDEWEB)

Mostafavi, P.; Zank, G. P. [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Webb, G. M. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

2017-05-20

The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

Energetic consumption levels and human development indexes

International Nuclear Information System (INIS)

Boa Nova, Antonio Carlos

1999-01-01

The article overviews the energetic consumption levels and human development indexes. The human development indexes are described based on the United Nations Development Programme. A comparison between the energetic consumption levels and human development indexes is also presented

Light-assisted, templated self-assembly using a photonic-crystal slab.

Science.gov (United States)

Jaquay, Eric; Martínez, Luis Javier; Mejia, Camilo A; Povinelli, Michelle L

2013-05-08

We experimentally demonstrate the technique of light-assisted, templated self-assembly (LATS). We excite a guided-resonance mode of a photonic-crystal slab with 1.55 μm laser light to create an array of optical traps. We demonstrate assembly of a square lattice of 520 nm diameter polystyrene particles spaced by 860 nm. Our results demonstrate how LATS can be used to fabricate reconfigurable structures with symmetries different from traditional colloidal self-assembly, which is limited by free energetic constraints.

Coherent Dynamics of Quantum Dots in Photonic-Crystal Cavities

DEFF Research Database (Denmark)

Madsen, Kristian Høeg

deviations. Similar measurements on a quantum dot in a photonic-crystal cavity sow a Rabi splitting on resonance, while time-resolved measurements prove that the system is in the weak coupling regime. Whle tuning the quantum dot through resonance of the high-Q mode we observe a strong and surprisingly...

Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas.

Science.gov (United States)

Hill, K W; Bitter, M; Delgado-Aparacio, L; Pablant, N A; Beiersdorfer, P; Schneider, M; Widmann, K; Sanchez del Rio, M; Zhang, L

2012-10-01

High resolution (λ∕Δλ ∼ 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-μm (55)Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10(-8)-10(-6) times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

X-ray crystal spectroscopy of JET - a design study

International Nuclear Information System (INIS)

Bateman, J.E.; Hobby, M.G.; Peacock, N.J.

1980-02-01

This study describes the design and specification of a diagnostic system to measure the space- and time-resolved x-ray spectrum from JET discharges with high-resolution crystal spectrometers operating in the wavelength region 1 - 15A. The specification is given in terms of sensitivity, resolving power, detector, and data handling requirements, special attention being given to the problems encountered in interfacing the spectrometer arrays to the torus vacuum system and in their disposition to the machine. Shielding requirements during the active mode are evaluated and a staged diagnostic is proposed to accommodate D - T operation. (U.K.)

Nonperturbative effects of energetic ions on Alfven eigenmodes

International Nuclear Information System (INIS)

Todo, Y.; Nakajima, N.; Shinohara, K.; Takechi, M.; Ishikawa, M.; Yamamoto, S.

2005-01-01

Linear properties and nonlinear evolutions of an energetic-ion driven instability in a JT-60U plasma were investigated using a simulation code for magnetohydrodynamics and energetic particles. The spatial profile of the unstable mode peaks near the plasma center where the safety factor profile is flat. The unstable mode is not a toroidal Alfven eigenmode (TAE) because the spatial profile deviates from the expected location of TAE and the spatial profile consists of a single primary harmonic m/n = 2/1 where m, n are poloidal and toroidal mode numbers. The real frequency of the unstable mode is close to the experimental starting frequency of the fast frequency sweeping mode. The simulation results demonstrate that the energetic ion orbit width and the energetic ion pressure significantly broaden radial profile of the unstable mode. For the smallest value among the investigated energetic ion orbit width, the unstable mode is localized within 20% of the minor radius. This gives an upper limit of the spatial profile width of the unstable mode which the magnetohydrodynamic effects alone can induce. For the experimental condition of the JT-60U plasma, the energetic ions broaden the spatial profile of the unstable mode by a factor of 3 compared with the smallest orbit width case. The unstable mode is primarily induced by the energetic particles. It is demonstrated that the frequency shifts both upward and downward in the nonlinear evolution at the rate close to that of the fast frequency sweeping mode. In addition to the energetic particle mode in the JT-60U plasma, an investigation of TAE in an LHD-like plasma using the simulation code for the helical coordinate system is reported. (author)

Nonperturbative effects of energetic ions on Alfven eigenmodes

International Nuclear Information System (INIS)

Todo, Y.; Nakajima, N.; Shinohara, Kouji; Takechi, Manabu; Ishikawa, Masao

2005-01-01

Linear properties and nonlinear evolutions of an energetic-ion driven instability in a JT-60U plasma were investigated using a simulation code for magnetohydrodynamics and energetic particles. The spatial profile of the unstable mode peaks near the plasma center where the safety factor profile is flat. The unstable mode is not a toroidal Alfven eigenmode (TAE) because the spatial profile deviates from the expected location of TAE and the spatial profile consists of a single primary harmonic m/n=2/1 where m, n are poloidal and toroidal mode numbers. The real frequency of the unstable mode is close to the experimental starting frequency of the fast frequency sweeping mode. The simulation results demonstrate that the energetic ion orbit width and the energetic ion pressure significantly broaden radial profile of the unstable mode. For the smallest value among the investigated energetic ion orbit width, the unstable mode is localized within 20% of the minor radius. This gives an upper limit of the spatial profile width of the unstable mode which the magnetohydrodynamic effects alone can induce. For the experimental condition of the JT-60U plasma, the energetic ions broaden the spatial profile of the unstable mode by a factor of 3 compared with the smallest orbit width case. The unstable mode is primarily induced by the energetic particles. It is demonstrated that the frequency shifts both upward and downward in the nonlinear evolution at the rate close to that of the fast frequency sweeping mode. In addition to the energetic particle mode in the JT-60U plasma, an investigation of TAE in an LHD-like plasma using the simulation code for the helical coordinate system is reported. (author)

Ecological problems of thermonuclear energetics. Review

Energy Technology Data Exchange (ETDEWEB)

Sivintsev, Yu V

1980-01-01

A review of preliminary quantitative estimates of radiation hazard of thermonuclear reactors is presented. Main attention is given to three aspects: nonradiation effect on environment, radionuclide blow-ups at normal operation and emergency situations with their consequences. The given data testify to great radiological advantages of thermonuclear energetics as compared with the modern nuclear energetics with thermal and prospective fast reactors.

Photonic Crystal Sensors Based on Porous Silicon

Directory of Open Access Journals (Sweden)

Claudia Pacholski

2013-04-01

Full Text Available Porous silicon has been established as an excellent sensing platform for the optical detection of hazardous chemicals and biomolecular interactions such as DNA hybridization, antigen/antibody binding, and enzymatic reactions. Its porous nature provides a high surface area within a small volume, which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochemial etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Pérot based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential.

Photonic Crystal Sensors Based on Porous Silicon

Science.gov (United States)

Pacholski, Claudia

2013-01-01

Porous silicon has been established as an excellent sensing platform for the optical detection of hazardous chemicals and biomolecular interactions such as DNA hybridization, antigen/antibody binding, and enzymatic reactions. Its porous nature provides a high surface area within a small volume, which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochemial etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Pérot based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential. PMID:23571671

Quantitative characterization of new supramolecular synthons involving fluorine atoms in the crystal structures of di- and tetrafluorinated benzamides.

Science.gov (United States)

Mondal, Pradip Kumar; Yadav, Hare Ram; Choudhury, Angshuman Roy; Chopra, Deepak

2017-10-01

Strong hydrogen bonds play a significant role in crystal packing. In particular, the involvement of interactions involving fluorine in controlling the crystal packing requires appropriate attention, especially in the presence of other strong hydrogen bonds. In the present study, a detailed quantitative assessment has been performed of the nature, energetics and topological properties derived from the electron density in model compounds based on fluorinated benzamides (a total of 46 fluorine-substituted benzamides containing multiple fluorine atoms) in the solid state. The primary motivation in the design of such molecules is to enhance the acidity of the interacting H atoms in the presence of an increasing number of F atoms on the molecular scaffold, resulting in increased propensity towards the formation of intermolecular interactions involving organic fluorine. This exercise has resulted in the identification of new and frequently occurring supramolecular synthons involving F atoms in the packing of molecules in the solid state. The energetics associated with short and directional intermolecular Csp 2 -H...F-Csp 2 interactions with significantly high electrostatic contributions is noteworthy, and the topological analysis reveals the bonding character of these ubiquitous interactions in crystal packing in addition to the presence of Csp 2 -F...F-Csp 2 contacts.

Spatially-resolved luminescence spectroscopy of CdSe quantum dots synthesized in ionic liquid crystal matrices

Energy Technology Data Exchange (ETDEWEB)

Magaryan, K.A., E-mail: xmagaros@gmail.com [Moscow State Pedagogical University, 29 Malaya Pirogovskaya Str., Moscow 119992 (Russian Federation); Mikhailov, M.A. [Moscow State Pedagogical University, 29 Malaya Pirogovskaya Str., Moscow 119992 (Russian Federation); Karimullin, K.R. [Moscow State Pedagogical University, 29 Malaya Pirogovskaya Str., Moscow 119992 (Russian Federation); Institute for Spectroscopy of RAS, 5 Fizicheskaya Str., Troitsk, Moscow 142190 (Russian Federation); E.K. Zavoyski Kazan Physical-Technical Institute of RAS, 10/7 Sibirski trakt Str., Kazan 420029 (Russian Federation); Knyazev, M.V.; Eremchev, I.Y. [Institute for Spectroscopy of RAS, 5 Fizicheskaya Str., Troitsk, Moscow 142190 (Russian Federation); Naumov, A.V. [Moscow State Pedagogical University, 29 Malaya Pirogovskaya Str., Moscow 119992 (Russian Federation); Institute for Spectroscopy of RAS, 5 Fizicheskaya Str., Troitsk, Moscow 142190 (Russian Federation); Vasilieva, I.A. [Moscow State Pedagogical University, 29 Malaya Pirogovskaya Str., Moscow 119992 (Russian Federation); Klimusheva, G.V. [Institute of Physics, NAS of Ukraine, 46 Prospect Nauki, Kiev 03028 (Ukraine)

2016-01-15

The paper is devoted to investigation of luminescence properties of new quantum dot (QD)-doped materials. We studied CdSe QDs (1.8 nm and 2.3 nm) grown inside of a liquid crystalline cadmium alcanoate matrix. Temperature dependence of parameters of fluorescence spectra obtained in a wide temperature range using epi-luminescence microscopy technique was analyzed. Spatially-resolved luminescence images were measured for the areas of the samples of 150×150 µm{sup 2}. Strong correlation between fluorescence spectra and sample structure was observed. - Highlights: • Glassy matrix with CdSe quantum dots inside fabricated in liquid crystalline mesophase. • Study of luminescence properties in a wide range of low temperatures. • Strong dependence of the luminescence spectra on spatial inhomogeneities. • Spatially-resolved luminescence imaging of quantum dots in liquid crystalline matrix.

Spatially-resolved luminescence spectroscopy of CdSe quantum dots synthesized in ionic liquid crystal matrices

International Nuclear Information System (INIS)

Magaryan, K.A.; Mikhailov, M.A.; Karimullin, K.R.; Knyazev, M.V.; Eremchev, I.Y.; Naumov, A.V.; Vasilieva, I.A.; Klimusheva, G.V.

2016-01-01

The paper is devoted to investigation of luminescence properties of new quantum dot (QD)-doped materials. We studied CdSe QDs (1.8 nm and 2.3 nm) grown inside of a liquid crystalline cadmium alcanoate matrix. Temperature dependence of parameters of fluorescence spectra obtained in a wide temperature range using epi-luminescence microscopy technique was analyzed. Spatially-resolved luminescence images were measured for the areas of the samples of 150×150 µm 2 . Strong correlation between fluorescence spectra and sample structure was observed. - Highlights: • Glassy matrix with CdSe quantum dots inside fabricated in liquid crystalline mesophase. • Study of luminescence properties in a wide range of low temperatures. • Strong dependence of the luminescence spectra on spatial inhomogeneities. • Spatially-resolved luminescence imaging of quantum dots in liquid crystalline matrix.

Energy-resolved photoemission studies of Be-containing surfaces for fusion; Energievariierte Photoemissionsstudien an berylliumhaltigen Oberflaechen fuer die Fusion

Energy Technology Data Exchange (ETDEWEB)

Koeppen, Martin

2013-02-04

Fusion research aims at the exploitation of the deuterium-tritium reaction for energy production. Next step on the roadmap is the construction of the experimental reactor ITER. The three elements beryllium, carbon and tungsten are to be used as armour materials for the vacuum vessel. After erosion due to plasma processes, these materials are transported and redeposited together with plasma impurities like oxygen from surface oxides. This leads to the formation of compounds by chemical reactions and diffusive processes, induced both by elevated temperatures and implantation of energetic particles. Due to the complexity of the induced surface processes, a method is required which is capable of both qualitative and quantitative analysis of the involved chemical species. X-ray photoelectron spectroscopy (XPS) provides the chemical analysis. Since diffusive processes play an important role in solid-state reactions, a depth-resolved method is required. In this work, energy-resolved XPS using synchrotron radiation with variable photon energies is extended towards a quantitative depth-resolved analysis. For the quantitative analysis a new model is derived which calculates the depth-resolved composition and the respective composition-dependent electron inelastic mean free path in a self-consistent way. Input is the XPS data which is normalized with all parameters influencing the photoelectron intensities. This fully quantitative model is applied to describe the interaction of energetic oxygen ions with the beryllium-tungsten alloy Be{sub 2}W. Oxygen ions from the plasma are able to interact with plasma facing materials. Formation of Be{sub 2}W is to be expected at the first wall and in the divertor region of ITER. Irradiation of this alloy leads to its decompositions. After decomposition, formation of beryllium oxide BeO is preferred compared to formation of tungsten oxides. Heating to 600K leads to chemical reduction of tungsten oxides. Metallic Be acts as reduction agent

Multiscale Modeling of Grain Boundaries in ZrB2: Structure, Energetics, and Thermal Resistance

Science.gov (United States)

Lawson, John W.; Daw, Murray S.; Squire, Thomas H.; Bauschlicher, Charles W., Jr.

2012-01-01

A combination of ab initio, atomistic and finite element methods (FEM) were used to investigate the structures, energetics and lattice thermal conductance of grain boundaries for the ultra high temperature ceramic ZrB2. Atomic models of idealized boundaries were relaxed using density functional theory. Information about bonding across the interfaces was determined from the electron localization function. The Kapitza conductance of larger scale versions of the boundary models were computed using non-equilibrium molecular dynamics. The interfacial thermal parameters together with single crystal thermal conductivities were used as parameters in microstructural computations. FEM meshes were constructed on top of microstructural images. From these computations, the effective thermal conductivity of the polycrystalline structure was determined.

Crystal spectroscopy of silicon aero-gel end-caps driven by a dynamic hohlraum on Z

International Nuclear Information System (INIS)

Nash, T.J.; Sanford, T.W.L.; Mock, R.C.; Leeper, R.J.; Chandler, G.A.; Bailey, J.E.; McKenney, J.L.; Mehlhorn, T.A.; Seaman, J.F.; McGurn, J.; Schroen, D.; Russell, C.; Lake, P.E.; Jobe, D.O.; Gilliland, T.; Nielsen, D.S.; Lucas, J.; Moore, T.; Torres, J.A.; MacFarlane, J.J.; Apruzese, J.P.; Chrien, R.; Idzorek, G.; Peterson, D.L.; Watt, R.

2005-01-01

We present results from crystal spectroscopic analysis of silicon aero-gel foams heated by dynamic hohlraums on Z. The dynamic hohlraum on Z creates a radiation source with a 230-eV average temperature over a 2.4-mm diameter. In these experiments silicon aero-gel foams with 10-mg/cm3 densities and 1.7-mm lengths were placed on both ends of the dynamic hohlraum. Several crystal spectrometers were placed both above and below the z-pinch to diagnose the temperature of the silicon aero-gel foam using the K-shell lines of silicon. The crystal spectrometers were (1) temporally integrated and spatially resolved, (2) temporally resolved and spatially integrated, and (3) both temporally and spatially resolved. The results indicate that the dynamic hohlraum heats the silicon aero-gel to approximately 150-eV at peak power. As the dynamic hohlraum source cools after peak power the silicon aero-gel continues to heat and jets axially at an average velocity of approximately 50-cm/μs. The spectroscopy has also shown that the reason for the up/down asymmetry in radiated power on Z is that tungsten enters the line-of-sight on the bottom of the machine much more than on the top

Segregation and redistribution of end-of-process energetic materials

International Nuclear Information System (INIS)

McCabe, R.A.; Cummins, B.; Gonzalez, M.A.

1993-03-01

A system recovering then recycling or reusing end-of-process energetic materials has been developed at the Lawrence Livermore National Laboratory (LLNL). The system promotes separating energetic materials with high potential for reuse or recycling from those that have no further value. A feature of the system is a computerized electronic bulletin board for advertising the availability of surplus and recovered energetic materials and process chemicals to LLNL researchers, and for posting energetic materials, ''want ads.'' The system was developed and implemented to promote waste minimization and pollution prevention at LLNL

Assessment of accident energetics in LMFBR core-disruptive accidents

International Nuclear Information System (INIS)

Fauske, H.K.

1977-01-01

An assessment of accident energetics in LMFBR core-disruptive accidents is given with emphasis on the generic issues of energetic recriticality and energetic fuel-coolant interaction events. Application of a few general behavior principles to the oxide-fueled system suggests that such events are highly unlikely following a postulated core meltdown event

The X-ray crystal bichromator – possible modifications and applications

Energy Technology Data Exchange (ETDEWEB)

Hrdý, Jaromír, E-mail: hrdy@fzu.cz

2017-05-11

The X-ray crystal bichromator is a device which delivers two arbitrarily chosen wavelengths in one beam. The principle and alignment was described in our previous work (Hrdý et al., 2016). With some modifications this device may be used for time-resolved experiments and dual energy imaging.

Heliospheric Observations of Energetic Particles

Science.gov (United States)

Summerlin, Errol J.

2011-01-01

Heliospheric observations of energetic particles have shown that, on long time averages, a consistent v^-5 power-law index arises even in the absence of transient events. This implies an ubiquitous acceleration process present in the solar wind that is required to generate these power-law tails and maintain them against adiabatic losses and coulomb-collisions which will cool and thermalize the plasma respectively. Though the details of this acceleration process are being debated within the community, most agree that the energy required for these tails comes from fluctuations in the magnetic field which are damped as the energy is transferred to particles. Given this source for the tail, is it then reasonable to assume that the turbulent LISM should give rise to such a power-law tail as well? IBEX observations clearly show a power-law tail of index approximately -5 in energetic neutral atoms. The simplest explanation for the origins of these ENAs are that they are energetic ions which have charge-exchanged with a neutral atom. However, this would imply that energetic ions possess a v^-5 power-law distribution at keV energies at the source of these ENAs. If the source is presumed to be the LISM, it provides additional options for explaining the, so called, IBEX ribbon. This presentation will discuss some of these options as well as potential mechanisms for the generation of a power-law spectrum in the LISM.

Physics of energetic ions

International Nuclear Information System (INIS)

1999-01-01

Physics knowledge (theory and experiment) in energetic particles relevant to design of a reactor scale tokamak is reviewed, and projections for ITER are provided in this Chapter of the ITER Physics Basis. The review includes single particle effects such as classical alpha particle heating and toroidal field ripple loss, as well as collective instabilities that might be generated in ITER plasmas by energetic alpha particles. The overall conclusion is that fusion alpha particles are expected to provide an efficient plasma heating for ignition and sustained burn in the next step device. The major concern is localized heat loads on the plasma facing components produced by alpha particle loss, which might affect their lifetime in a tokamak reactor. (author)

Energetic particle observations at the subsolar magnetopause

Directory of Open Access Journals (Sweden)

A. A. Eccles

Full Text Available The pitch-angle distributions (PAD of energetic particles are examined as the ISEE-1 satellite crosses the Earth’s magnetopause near the subsolar point. The investigation focuses on the possible existence of a particular type of distribution that would be associated with a source of energetic particles in the high-latitude magnetosphere. PADs, demonstrating broad, persistent field-aligned fluxes filling a single hemisphere (upper/northern or lower/southern, were observed just sunward of the magnetopause current layer for an extended period of many minutes. These distributions are a direct prediction of a possible source of energetic particles located in the high altitude dayside cusp and we present five examples in detail of the three-dimensional particle distributions to demonstrate their existence. From these results, other possible causes of such PADs are examined.

Key words. Magnetospheric physics (energetic particles, precipitating; magnetopause, cusp and boundary layers; magnetospheric configuration and dynamics

Time-resolved SAXS studies of morphological changes in a blend of linear polyethylene with homogeneous ethylene-1-octene copolymer

Energy Technology Data Exchange (ETDEWEB)

Ślusarczyk, Czesław, E-mail: cslusarczyk@ath.bielsko.pl

2015-12-01

Isothermal melt crystallization in the 15/85 (m/m) blend of a high density polyethylene (HDPE) and a homogeneous ethylene copolymer with 5.5 mol% 1-octene was studied by time-resolved SAXS method with synchrotron radiation over a wide-range of crystallization temperatures. The SAXS profile was analyzed by means of the correlation function which allows to elucidate the evolution of the morphological parameters of polyethylene lamellar structure (long period (LP), thicknesses of crystalline (L{sub C}) and amorphous (L{sub A}) layers) during a crystallization process. It was found that for the samples crystallized at 100 °C, 120 °C and 122 °C L{sub C} increases with time. The lamellar thickening rate strongly depends on crystallization temperature. At 40 °C thickening of the crystalline layers does not occur. The time evolution of the lamellar structure in the blend studied confirms the role of hexyl branches of homogeneous copolymer in the crystallization process of polyethylene. The branches introduce steric constraints which hinder the crystallization of HDPE, thus decreasing the size of the HDPE lamellar crystals.

Electron excitations in BeAl2O4, Be2SiO4 and Be3Al2Si6O18 crystals

International Nuclear Information System (INIS)

Ivanov, V.Yu.; Pustovarov, V.A.; Shlygin, E.S.; Korotaev, A.V.; Kruzhalov, A.V.

2005-01-01

Low-temperature (T = 7 K) time-resolved selectively photoexcited luminescence spectra (2-6 eV) and luminescence excitation spectra (8-35 eV) of wide-bandgap chrysoberyl BeAl 2 O 4 , phenacite Be 2 SiO 4 , and beryl Be 3 Al 2 Si 6 O 18 crystals have been studied using time-resolved VUV spectroscopy. Both the intrinsic luminescence of the crystals and the luminescence associated with structural defects were assigned. Energy transfer to impurity luminescence centers in alexandrite and emerald was investigated. Luminescence characteristics of stable crystal lattice defects were probed by 3.6-MeV accelerated helium ion beams [ru

Fixed target matrix for femtosecond time-resolved and in situ serial micro-crystallography

Directory of Open Access Journals (Sweden)

C. Mueller

2015-09-01

Full Text Available We present a crystallography chip enabling in situ room temperature crystallography at microfocus synchrotron beamlines and X-ray free-electron laser (X-FEL sources. Compared to other in situ approaches, we observe extremely low background and high diffraction data quality. The chip design is robust and allows fast and efficient loading of thousands of small crystals. The ability to load a large number of protein crystals, at room temperature and with high efficiency, into prescribed positions enables high throughput automated serial crystallography with microfocus synchrotron beamlines. In addition, we demonstrate the application of this chip for femtosecond time-resolved serial crystallography at the Linac Coherent Light Source (LCLS, Menlo Park, California, USA. The chip concept enables multiple images to be acquired from each crystal, allowing differential detection of changes in diffraction intensities in order to obtain high signal-to-noise and fully exploit the time resolution capabilities of XFELs.

Local layer structure of smectic liquid crystals by X-ray micro-diffraction

CERN Document Server

Takanishi, Y

2003-01-01

The local layer structure of smectic liquid crystal has been measured using time-resolved synchrotron X-ray micro-diffraction. Typical layer disorders observed in surface stabilized (anti-) ferroelectric liquid crystals, i.e. a stripe texture, a needed-like defect and a zigzag defect, are directly analyzed. The detailed analysis slows that the surface anchoring force due to the interaction between the liquid crystal molecule and the alignment thin film plays an important role to realize both the static and dynamic local layer structures. The layer structure of the circular domain observed in the liquid crystal of bent-shaped molecules found to depend on the applied electric field though the optical micrograph shows little difference. The frustrated, double and single layer structures of the bent-shaped molecule liquid crystal are determined depending on the terminal alkyl chain length. (author)

Energetic policies 2005-2030

International Nuclear Information System (INIS)

2008-01-01

This power point exhibition shows the following topics: energy analysis, production and use, supply and demand, consumption, energy sources, energetic prospective of Uruguay country, medium and long term perspectives.

Nonlocal continuum electrostatic theory predicts surprisingly small energetic penalties for charge burial in proteins.

Science.gov (United States)

Bardhan, Jaydeep P

2011-09-14

We study the energetics of burying charges, ion pairs, and ionizable groups in a simple protein model using nonlocal continuum electrostatics. Our primary finding is that the nonlocal response leads to markedly reduced solvent screening, comparable to the use of application-specific protein dielectric constants. Employing the same parameters as used in other nonlocal studies, we find that for a sphere of radius 13.4 Å containing a single +1e charge, the nonlocal solvation free energy varies less than 18 kcal/mol as the charge moves from the surface to the center, whereas the difference in the local Poisson model is ∼35 kcal/mol. Because an ion pair (salt bridge) generates a comparatively more rapidly varying Coulomb potential, energetics for salt bridges are even more significantly reduced in the nonlocal model. By varying the central parameter in nonlocal theory, which is an effective length scale associated with correlations between solvent molecules, nonlocal-model energetics can be varied from the standard local results to essentially zero; however, the existence of the reduction in charge-burial penalties is quite robust to variations in the protein dielectric constant and the correlation length. Finally, as a simple exploratory test of the implications of nonlocal response, we calculate glutamate pK(a) shifts and find that using standard protein parameters (ε(protein) = 2-4), nonlocal results match local-model predictions with much higher dielectric constants. Nonlocality may, therefore, be one factor in resolving discrepancies between measured protein dielectric constants and the model parameters often used to match titration experiments. Nonlocal models may hold significant promise to deepen our understanding of macromolecular electrostatics without substantially increasing computational complexity. © 2011 American Institute of Physics

Advances in magnetospheric physics, 1971--1974: energetic particles

International Nuclear Information System (INIS)

West, H.I. Jr.

1974-12-01

An account is given of energetic particle research in magnetospheric physics for the time period 1971--1974. Emphasis is on relating the various aspects of energetic particles to magnetospheric processes. 458 refs. (U.S.)

Sol-Gel Manufactured Energetic Materials

Science.gov (United States)

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

A versatile, highly-efficient, high-resolution von Hamos Bragg crystal x-ray spectrometer

International Nuclear Information System (INIS)

Vane, C.R.; Smith, M.S.; Raman, S.

1988-01-01

An efficient, high-resolution, vertical-focusing, Bragg crystal x-ray spectrometer has been specifically designed and constructed for use in measurements of x rays produced in collisions of energetic heavy ions. In this report the design and resulting operational characteristics of the final instrument are fully described. A wide variety of sample data is also included to illustrate the utility of this device in several areas of research. 14 refs., 38 figs

Structure and Stability of Molecular Crystals with Many-Body Dispersion-Inclusive Density Functional Tight Binding.

Science.gov (United States)

Mortazavi, Majid; Brandenburg, Jan Gerit; Maurer, Reinhard J; Tkatchenko, Alexandre

2018-01-18

Accurate prediction of structure and stability of molecular crystals is crucial in materials science and requires reliable modeling of long-range dispersion interactions. Semiempirical electronic structure methods are computationally more efficient than their ab initio counterparts, allowing structure sampling with significant speedups. We combine the Tkatchenko-Scheffler van der Waals method (TS) and the many-body dispersion method (MBD) with third-order density functional tight-binding (DFTB3) via a charge population-based method. We find an overall good performance for the X23 benchmark database of molecular crystals, despite an underestimation of crystal volume that can be traced to the DFTB parametrization. We achieve accurate lattice energy predictions with DFT+MBD energetics on top of vdW-inclusive DFTB3 structures, resulting in a speedup of up to 3000 times compared with a full DFT treatment. This suggests that vdW-inclusive DFTB3 can serve as a viable structural prescreening tool in crystal structure prediction.

Event localization in bulk scintillator crystals using coded apertures

Energy Technology Data Exchange (ETDEWEB)

Ziock, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN (United States); Braverman, J.B. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN (United States); Fabris, L.; Harrison, M.J.; Hornback, D.; Newby, J. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2015-06-01

The localization of radiation interactions in bulk scintillators is generally limited by the size of the light distribution at the readout surface of the crystal/light-pipe system. By finding the centroid of the light spot, which is typically of order centimeters across, practical single-event localization is limited to ~2 mm/cm of crystal thickness. Similar resolution can also be achieved for the depth of interaction by measuring the size of the light spot. Through the use of near-field coded-aperture techniques applied to the scintillation light, light transport simulations show that for 3-cm-thick crystals, more than a five-fold improvement (millimeter spatial resolution) can be achieved both laterally and in event depth. At the core of the technique is the requirement to resolve the shadow from an optical mask placed in the scintillation light path between the crystal and the readout. In this paper, experimental results are presented that demonstrate the overall concept using a 1D shadow mask, a thin-scintillator crystal and a light pipe of varying thickness to emulate a 2.2-cm-thick crystal. Spatial resolutions of ~1 mm in both depth and transverse to the readout face are obtained over most of the crystal depth.

Event localization in bulk scintillator crystals using coded apertures

International Nuclear Information System (INIS)

Ziock, K.P.; Braverman, J.B.; Fabris, L.; Harrison, M.J.; Hornback, D.; Newby, J.

2015-01-01

The localization of radiation interactions in bulk scintillators is generally limited by the size of the light distribution at the readout surface of the crystal/light-pipe system. By finding the centroid of the light spot, which is typically of order centimeters across, practical single-event localization is limited to ~2 mm/cm of crystal thickness. Similar resolution can also be achieved for the depth of interaction by measuring the size of the light spot. Through the use of near-field coded-aperture techniques applied to the scintillation light, light transport simulations show that for 3-cm-thick crystals, more than a five-fold improvement (millimeter spatial resolution) can be achieved both laterally and in event depth. At the core of the technique is the requirement to resolve the shadow from an optical mask placed in the scintillation light path between the crystal and the readout. In this paper, experimental results are presented that demonstrate the overall concept using a 1D shadow mask, a thin-scintillator crystal and a light pipe of varying thickness to emulate a 2.2-cm-thick crystal. Spatial resolutions of ~1 mm in both depth and transverse to the readout face are obtained over most of the crystal depth

Nano-crystal growth in cordierite glass ceramics studied with X-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Bras, Wim; Clark, Simon M.; Greaves, G. N.; Kunz, Martin; van Beek, W.; Radmilovic, V.

2009-01-16

The development of monodisperse crystalline particles in cordierite glass doped with Cr3+ after a two-step heat treatment is elucidated by a combination of time-resolved small and wide angle x-ray scattering (SAXS/WAXS) experiments with electron microscopy. The effects of bulk and surface crystallization can clearly be distinguished, and the crystallization kinetics of the bulk phase is characterized. The internal pressure due to structural differences between the crystalline and amorphous phase is measured but the physical cause of this pressure can not unambiguously be attributed. The combined measurements comprise a nearly full characterization of the crystallization processes and the resulting sample morphology.

The role of aging in resolving the ferrocyanide safety issue

International Nuclear Information System (INIS)

Babad, H.; Meacham, J.E.; Simpson, B.C.; Cash, R.J.

1993-08-01

A chemical process called aging, in which stored ferrocyanide waste could be dissolved and dispersed among waste tanks, or destroyed by radiolysis and hydrolysis, has been proposed at the Hanford Site. This paper summarizes the results of applied research, characterization, and modeling activities on Hanford Site ferrocyanide waste material that support the existence of a chemical aging mechanism. Test results from waste simulants and actual waste tank materials are presented and compared with theoretical estimates. Chemical and energetic behavior of the materials are the key indicators of destruction or dispersion. Screening experiments on vendor-prepared sodium nickel ferrocyanide and the initial results from core sampling support the concept that aging of ferrocyanide is taking place in the waste tanks at the Hanford Site. This report defines the concept of waste aging and explains the role that aging could play in resolving the Hanford Site ferrocyanide safety issue

Energetic matrix of Rio de Janeiro State, Brazil - 1994/2004

International Nuclear Information System (INIS)

1996-01-01

This book has been structured into three parts and three appendices. In the first part, named Energetic matrix of Rio de Janeiro State, the most important economic and social aspects of the State and the methodology for elaboration of economic and energetic scenarios has been detailed. In the second part, an analysis of seven consumption sectors components of the energetic matrix structure ( industrial, transports, residential, commercial, energetic, agriculture and cattle-breeding, non energetic) has been performed, with the objective of providing information on the present status and future prospects of energy consumption by sectors up to 2004. Finally, in the third part, the energy supply of Rio de Janeiro State for the consumption sectors has been discussed

Pilot tests of a PET detector using the TOF-PET ASIC based on monolithic crystals and SiPMs

International Nuclear Information System (INIS)

Aguilar, A.; González-Montoro, A.; González, A.J.; Hernández, L.; Monzó, J.M.; Benlloch, J.M.; Bugalho, R.; Ferramacho, L.

2016-01-01

In this work we show pilot tests of PET detector blocks using the TOF-PET ASIC, coupled to SiPM detector arrays and different crystal configurations. We have characterized the main ASIC features running calibration processes to compensate the time dispersion among the different ASIC/SiPM paths as well as for the time walk on the arrival of optical photons. The aim of this work is to use of LYSO monolithic crystals and explore their photon Depth of Interaction (DOI) capabilities, keeping good energy and spatial resolutions. First tests have been carried out with crystal arrays. Here we made it possible to reach a coincidence resolving times (CRT) of 370 ps FWHM, with energy resolutions better than 20% and resolving well 2 mm sized crystal elements. When using monolithic crystals, a single-pixel LYSO reference crystal helped to explore the CRT performance. We studied different strategies to provide the best timestamp determination in the monolithic scintillator. Times around 1 ns FWHM have been achieved in these pilot studies. In terms of spatial and energy resolution, values of about 3 mm and better than 30% were found, respectively. We have also demonstrated the capability of this system (monolithic and ASIC) to return accurate DOI information.

Time-resolving electron temperature diagnostic for ALCATOR C

International Nuclear Information System (INIS)

Fairfax, S.A.

1984-05-01

A diagnostic that provides time-resolved central electron temperatures has been designed, built, and tested on the ALCATOR C Tokamak. The diagnostic uses an array of fixed-wavelength x-ray crystal monochromators to sample the x-ray continuum and determine the absolute electron temperature. The resolution and central energy of each channel were chosen to exclude any contributions from impurity line radiation. This document describes the need for such a diagnostic, the design methodology, and the results with typical ALCATOR C plasmas. Sawtooth (m = 1) temperature oscillations were observed after pellet fueling of the plasma. This is the first time that such oscillations have been observed with an x-ray temperature diagnostic

Energetic magnetospheric protons in the plasma depletion layer

International Nuclear Information System (INIS)

Fuselier, S.A.

1992-01-01

Interplanetary magnetic field draping against the Earth's dayside subsolar magnetopause creates a region of reduced plasma density and increased magnetic field called the plasma depletion layer. In this region, leakage of energetic ions from the Earth's magnetosphere onto magnetic field lines in the plasma depletion layer can be studied without interference from ions accelerated at the Earth's quasi-parallel bow shock. Active Magnetospheric Particle Tracer Experiment/Charge Composition Explorer (AMPTE/CCE) observations for 13 plasma depletion layer events are used to determine the characteristics of energetic protons between a few keV/e and ∼100keV/e leaked from the magnetosphere. Results indicate that the leaked proton distributions resemble those in the magnetosphere except that they have lower densities and temperatures and much higher velocities parallel (or antiparallel) and perpendicular to the magnetic field. Compared to the low-energy magnetosheath proton distributions present in the depletion layer, the leaked energetic proton distributions typically have substantially higher flow velocities along the magnetic field indicate that the leaked energetic proton distributions to contribute to the energetic proton population seen upstream and downstream from the quasi-parallel bow shock. However, their contribution is small compared to the contribution from acceleration of protons at the bow shock because the leaked proton densities are on the order of 10 times smaller than the energetic proton densities typically observed in the vicinity of the quasi-parallel bow shock

Spectrally resolved thermally stimulated luminescence of irradiated anion-defective alumina single crystals

Energy Technology Data Exchange (ETDEWEB)

Kortov, V., E-mail: vskortov@mail.ru [Ural Federal University, Mira Str. 19, 620002 Ekaterinburg (Russian Federation); Lushchik, A.; Nagirnyi, V. [Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu (Estonia); Ananchenko, D. [Ural Federal University, Mira Str. 19, 620002 Ekaterinburg (Russian Federation); Romet, I. [Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu (Estonia)

2017-06-15

Thermally stimulated luminescence (TSL) spectra in the 313–580 K temperature range have been studied in anion-defective alumina crystals (named in literature as Al{sub 2}O{sub 3}:C) exposed to different irradiation doses. The TSL curve features two peaks with the maxima at T{sub m1}=437 K and T{sub m2}=565 K. The TSL spectrum of the first peak contains the emission of F centers and the R line of Cr{sup 3+} impurity ions. The absence of the emission of F{sup +} centers indicates that electron traps are responsible for the first dosimetric TSL peak. The TSL spectrum of the second peak features emission bands of F, F{sup +} centers, R line as well as a wide band centered at 550 nm and associated with the formation of aggregate centers (F{sub 2} and F{sub 2}{sup 2+}) under irradiation. Possible excitation mechanisms of the TSL emission bands that involve both electron and hole traps related to anion vacancies and impurities are discussed. - Highlights: •TSL curve of alumina crystals features peaks at 437 and 565 K. •There are emission bands of 410 and 695 nm in the TSL spectrum of the first peak. •TSL spectrum of the second peak features bands of F, F{sub 2}-type centers and the R line of trivalent chromium. •Excitation mechanisms of the emission bands in TSL spectra are discussed.

Growth, optical and EPR studies of {sup 151}Eu{sup 2+}:YAG single crystals

Energy Technology Data Exchange (ETDEWEB)

Petrosyan, A.G., E-mail: pet@ipr.sci.am [Institute for Physical Research, National Academy of Sciences, Ashtarak, 0203 (Armenia); Asatryan, H.R. [Ioffe Physical-Technical Institute, Politekhnicheskaya ul. 26, St. Petersburg, 194021 (Russian Federation); Hovhannesyan, K.L.; Derdzyan, M.V. [Institute for Physical Research, National Academy of Sciences, Ashtarak, 0203 (Armenia); Feofilov, S.P. [Ioffe Physical-Technical Institute, Politekhnicheskaya ul. 26, St. Petersburg, 194021 (Russian Federation); Eganyan, A.V.; Sargsyan, R.S. [Institute for Physical Research, National Academy of Sciences, Ashtarak, 0203 (Armenia)

2017-01-01

Single crystals of {sup 151}Eu:YAG were grown by the vertical Bridgman method using Eu{sub 2}O{sub 3} with isotopic enrichment of {sup 151}Eu of 97.5%. Additional Hf{sup 4+}or Si{sup 4+} ions were introduced to favor a high concentrations of Eu{sup 2+}. As compared to Eu:YAG with natural isotope composition, the EPR spectra of YAG doped with {sup 151}Eu isotope show a reduced number of hyperfine structure components and a well-resolved structure of a bigger number of electronic transitions. Optical properties of obtained crystals and the effects of heat treatments under oxidizing and reducing conditions are reported. Based on the analysis of Eu{sup 3+} distribution in oxidized Eu,Hf:YAG, in comparison to that in Eu:YAG, the concentration of Eu{sup 2+} in as-grown Eu,Hf:YAG is determined. - Highlights: • YAG:Eu,Hf single crystals containing only {sup 151}Eu isotopes were prepared. • isotopic enriched crystals gave a well-resolved EPR hyperfine structure of Eu{sup 2+} centers. • the redox ratio was followed through the Eu{sup 2+} associated absorption band at 250 nm. • the band intensities at 378 nm correlate with the Eu{sup 2+} concentration.

Cutting and machining energetic materials with a femtosecond laser

Energy Technology Data Exchange (ETDEWEB)

Roeske, Frank; Benterou, Jerry; Lee, Ronald; Roos, Edward [Energetic Materials Center, Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA 94550 (United States)

2003-04-01

A femtosecond (fs) laser has been used as a tool for solving many problems involving access, machining, disassembly, inspection and avoidance of undesirable hazardous waste streams in systems containing energetic materials. Because of the unique properties of the interaction of ultrashort laser pulses with matter, the femtosecond laser can be used to safely cut these energetic materials in a precise manner without creating an unacceptable waste stream. Many types of secondary high explosives (HE) and propellants have been cut with the laser for a variety of applications ranging from disassembly of aging conventional weapons (demilitarization), inspection of energetic components of aging systems to creating unique shapes of HE for purposes of initiation and detonation physics studies. Hundreds of samples of energetic materials have been cut with the fs laser without ignition and, in most cases, without changing the surface morphology of the cut surfaces. The laser has also been useful in cutting nonenergetic components in close proximity to energetic materials. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Observation of plastic deformation in freestanding single crystal Au nanowires

International Nuclear Information System (INIS)

Lee, Dongyun; Zhao Manhong; Wei Xiaoding; Chen Xi; Jun, Seong C.; Hone, James; Herbert, Erik G.; Oliver, Warren C.; Kysar, Jeffrey W.

2006-01-01

Freestanding single crystal nanowires of gold were fabricated from a single grain of pure gold leaf by standard lithographic techniques, with center section of 7 μm in length, 250 nm in width, and 100 nm in thickness. The ends remained anchored to a silicon substrate. The specimens were deflected via nanoindenter until plastic deformation was achieved. Nonlocalized and localized plastic deformations were observed. The resulting force-displacement curves were simulated using continuum single crystal plasticity. A set of material parameters which closely reproduce the experimental results suggests that the initial critical resolved shear stress was as high as 135 MPa

Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps

Energy Technology Data Exchange (ETDEWEB)

Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, Bamberg 96049 (Germany); Beiersdorfer, P.; Magee, E. W.; Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2016-11-15

We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5°–3° spectral range at Bragg angles around 51.3°. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (>10 000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument’s spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in the first and second order and derived the ion temperatures from these lines. We have also made use of the 50 μm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.

Microphase Separation Controlled beta-Sheet Crystallization Kinetics in Fibrous Proteins

International Nuclear Information System (INIS)

Hu, X.; Lu, Q.; Kaplan, D.; Cebe, P.

2009-01-01

Silk is a naturally occurring fibrous protein with a multiblock chain architecture. As such, it has many similarities with synthetic block copolymers, including the possibility for e-sheet crystallization restricted within the crystallizable blocks. The mechanism of isothermal crystallization kinetics of e-sheet crystals in silk multiblock fibrous proteins is reported in this study. Kinetics theories, such as Avrami analysis which was established for studies of synthetic polymer crystal growth, are for the first time extended to investigate protein self-assembly in e-sheet rich Bombyx mori silk fibroin samples, using time-resolved Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and synchrotron real-time wide-angle X-ray scattering (WAXS). The Avrami exponent, n, was close to 2 for all methods and crystallization temperatures, indicating formation of e-sheet crystals in silk proteins is different from the 3-D spherulitic crystal growth found in synthetic polymers. Observations by scanning electron microscopy support the view that the protein structures vary during the different stages of crystal growth, and show a microphase separation pattern after chymotrypsin enzyme biodegradation. We present a model to explain the crystallization of the multiblock silk fibroin protein, by analogy to block copolymers: crystallization of e-sheets occurs under conditions of geometrical restriction caused by phase separation of the crystallizable and uncrystallizable blocks. This crystallization model could be widely applicable in other proteins with multiblock (i.e., crystallizable and noncrystallizable) domains.

Energetic particle physics with applications in fusion and space plasmas

International Nuclear Information System (INIS)

Cheng, C.Z.

1997-01-01

Energetic particle physics is the study of the effects of energetic particles on collective electromagnetic (EM) instabilities and energetic particle transport in plasmas. Anomalously large energetic particle transport is often caused by low frequency MHD instabilities, which are driven by these energetic particles in the presence of a much denser background of thermal particles. The theory of collective energetic particle phenomena studies complex wave-particle interactions in which particle kinetic physics involving small spatial and fast temporal scales can strongly affect the MHD structure and long-time behavior of plasmas. The difficulty of modeling kinetic-MHD multiscale coupling processes stems from the disparate scales which are traditionally analyzed separately: the macroscale MHD phenomena are studied using the fluid MHD framework, while microscale kinetic phenomena are best described by complicated kinetic theories. The authors have developed a kinetic-MHD model that properly incorporates major particle kinetic effects into the MHD fluid description. For tokamak plasmas a nonvariational kinetic-MHD stability code, the NOVA-K code, has been successfully developed and applied to study problems such as the excitation of fishbone and Toroidal Alfven Eigenmodes (TAE) and the sawtooth stabilization by energetic ions in tokamaks. In space plasmas the authors have employed the kinetic-MHD model to study the energetic particle effects on the ballooning-mirror instability which explains the multisatellite observation of the stability and field-aligned structure of compressional Pc 5 waves in the magnetospheric ring current plasma

Time-resolved pump-probe X-ray absorption fine structure spectroscopy of Gaq3

International Nuclear Information System (INIS)

Dicke, Benjamin

2013-01-01

of Gaq 3 was analyzed and presents one of the first time-resolved measurements at PETRA III. In addition to pump-probe XAFS spectroscopy, different phases of Gaq 3 and Alq 3 in form of powder, crystal, film and solution were analyzed by means of UV-VIS and fluorescence spectroscopy. Electronic and optical differences of the molecules related to the particular form could be revealed. Gaq 3 in benzyl alcohol solution and Gaq 3 in crystalline form exhibit very similar optical features, indicating similar structural properties. The various preparation techniques used to obtain the sample forms are presented in this thesis. Analyzing the differences among the diverse sample forms helps to answer the question on how the conclusions extracted from sample systems in liquid form can be transferred to the ones in crystal form or film form, the latter appearing in organic light emitting diodes. The future goal of this research project is the direct measurement of the excited state structure of Alq 3 as well as Gaq 3 , and similar sample systems by time-resolved X-ray crystallography. The sample crystals have to fulfill specific requirements especially for the laser induced photoexcitation process. In this thesis a newly developed preparation method for low roughness singe crystal slices is presented. These crystal slices can be used for future perspective time-resolved X-ray crystallography experiments.

Neoclassical transport of energetic beam ions in the Large Helical Device

International Nuclear Information System (INIS)

Murakami, Sadayoshi; Yamada, Hiroshi; Kaneko, Osamu

2000-01-01

The neoclassical (collisional) transport of energetic ions is investigated by the global neoclassical transport simulation in the Large Helical Device (LHD). The steady state distributions of energetic ions are evaluated assuming an energetic particle source by NBI heating (tangentally injected). Significant radial transport of energetic ions can be seen due to the radial motion of trapped particles in the velocity region below near critical velocity. Our simulation results show relatively good agreements with the experimental results of fast particle measurements in the LHD. This suggests an important role of neoclassical transport in the radial transport process of energetic ions in heliotrons. (author)

High-energy e- /e+ spectrometer via coherent interaction in a bent crystal

Science.gov (United States)

Bagli, Enrico; Guidi, Vincenzo; Howard, Alexander

2018-01-01

We propose a novel spectrometer based on the crystal channeling effect capable of discriminating between positive and negative particles well beyond the TeV energy scale. The atomic order of a crystalline structure generates an electrostatic field built up by all the atoms in the crystals, which confines charged particle trajectories between neighbouring atomic planes. Through such an interaction in a tiny curved crystal, the same dynamical action on the highest energy particles as that of a huge superconducting magnet is achieved. Depending on the charge sign, points of equilibrium of the oscillatory motion under channeling lie between or on atomic planes for positive and negative particles, respectively, forcing positive particles to stably oscillate far from the planes, while negative ones repeatedly cross them. The different interaction rate with atomic planes causes a tremendous discrepancy between the deflection efficiency of positive and negative particles under channeling. We suggest the use of interactions between charged particles and oriented bent crystals as a novel non-cryogenic passive charge spectrometer to aid the search for dark matter in the Universe in satellite-borne experiment. The limited angular acceptance makes this technique particularly suited for directional local sources of energetic charged particles.

Life cycles of energetic systems

International Nuclear Information System (INIS)

Adnot, Jerome; Marchio, Dominique; Riviere, Philippe; Duplessis, B.; Rabl, A.; Glachant, M.; Aggeri, F.; Benoist, A.; Teulon, H.; Daude, J.

2012-01-01

This collective publication aims at being a course for students in engineering of energetic systems, i.e. at learning how to decide to accept or discard a project, to select the most efficient system, to select the optimal system, to select the optimal combination of systems, and to classify independent systems. Thus, it presents methods to analyse system life cycle from an energetic, economic and environmental point of view, describes how to develop an approach to the eco-design of an energy consuming product, how to understand the importance of hypotheses behind abundant and often contradicting publicised results, and to be able to criticise or to put in perspective one's own analysis. The first chapters thus recall some aspects of economic calculation, introduce the assessment of investment and exploitation costs of energetic systems, describe how to assess and internalise environmental costs, present the territorial carbon assessment, discuss the use of the life cycle assessment, and address the issue of environmental management at a product scale. The second part proposes various case studies: an optimal fleet of thermal production of electric power, the eco-design of a refrigerator, the economic and environmental assessment of wind farms

Nuclear energetics all over the world

International Nuclear Information System (INIS)

Wojcik, T.

2000-01-01

The actual state and tendencies of nuclear power further development for different world regions have been presented and discussed. The problem of safety of energetic nuclear reactors, radioactive waste management and related problems have been discussed in respect of regulations in different countries. The economical aspects of nuclear energetics in comparison with different fossil fuel power plants exploitation costs has been presented as well. The official state of international organizations (IAEA, WANO, HASA etc.) have been also shown in respect to subject presented

Radhard optical patchcords and packaging for satellites using liquid crystal polymers

Science.gov (United States)

O'Riorden, S.; Mahapatra, A.

2017-11-01

There are many advantages to employing fiber optics for high capacity satellite communication. However, optical cables can be susceptible to high radiation, temperature extremes and vacuum environment. Any hardware used in these systems must be rugged, durable and immune to the detrimental effects of the aforementioned conditions. Standard COTS optical fiber will darken when exposed to high levels of radiation limiting the effectiveness of the communications system. Of particular concern to satellites in GEO are energetic electrons, bursts of heavy particles due to solar storms which can cause total dose and single event effects (SEE). Conventional fiber optic cables have several issues performing in high radiation environments. Linden has patented and developed a novel cable using an extruded layer of Liquid Crystal Polymer (LCP) applied to commercially available fiber. Total dose effects are minimized by shielding with Liquid Crystal Polymer jacketing. It is a simple, inexpensive way to increase the radiation shielding and mechanical performance of cables in satellites while concomitantly providing hermeticity and thus increased fatigue factor for optical glass. • LCPs exposed to 5000 Mrad dose of gamma rays retain in excess of 90% of their mechanical properties. • LCPs exposed to 1 Mrad radiation dose with energetic protons retain almost 100% of their mechanical strength. Tensile modulus increases with exposure to the radiation. • Weight for weight the proton absorbing power of LCP is 25% better than that of aluminum. We will present experimental data on radhard optical patchcords.

Energetic certification in Europe

International Nuclear Information System (INIS)

1998-01-01

At community level the problem of energy quality control in a building was introduced by EEC recommendation n. 93/76 in 1993. In this item are reported some notes on energetic certification in European countries [it

Experimental study and numerical simulation of the plastic deformation of zirconium single crystals

International Nuclear Information System (INIS)

Lebon, C.

2011-01-01

There is only few experimental data in the literature on the zirconium single crystals and no constitutive laws for this single crystal material are provided. The goal of this work is then to create an experimental database like the Critical Resolved Shear Stress (CRSS) for the prismatic slip, the strain-hardening, the activation of the prismatic glide system and the activation volumes. We determine theses parameters from image correlation method. Then, we develop a new multi-scale approach using dislocations dynamics concept and finite element computations. Finally, a first single crystal constitutive law for the zirconium is proposed and a good agreement with the experimental data is obtained. (author) [fr

Energetic Particles Dynamics in Mercury's Magnetosphere

Science.gov (United States)

Walsh, Brian M.; Ryou, A.S.; Sibeck, D. G.; Alexeev, I. I.

2013-01-01

We investigate the drift paths of energetic particles in Mercury's magnetosphere by tracing their motion through a model magnetic field. Test particle simulations solving the full Lorentz force show a quasi-trapped energetic particle population that gradient and curvature drift around the planet via "Shabansky" orbits, passing though high latitudes in the compressed dayside by equatorial latitudes on the nightside. Due to their large gyroradii, energetic H+ and Na+ ions will typically collide with the planet or the magnetopause and will not be able to complete a full drift orbit. These simulations provide direct comparison for recent spacecraft measurements from MESSENGER. Mercury's offset dipole results in an asymmetric loss cone and therefore an asymmetry in particle precipitation with more particles precipitating in the southern hemisphere. Since the planet lacks an atmosphere, precipitating particles will collide directly with the surface of the planet. The incident charged particles can kick up neutrals from the surface and have implications for the formation of the exosphere and weathering of the surface

Energetic Materials Effects on Essential Soil Processes: Decomposition of Orchard Grass (Dactylis glomerata) Litter in Soil Contaminated with Energetic Materials

Science.gov (United States)

2014-02-01

availabilities of their respective food sources (bacteria and fungi ), were also unaffected-or-increasing in soil with CL-20 treatments. This is...ENERGETIC MATERIALS EFFECTS ON ESSENTIAL SOIL PROCESSES: DECOMPOSITION OF ORCHARD...GRASS (DACTYLIS GLOMERATA) LITTER IN SOIL CONTAMINATED WITH ENERGETIC MATERIALS ECBC-TR-1199 Roman G. Kuperman Ronald T. Checkai Michael Simini

Computational studies on energetic properties of nitrogen-rich ...

Indian Academy of Sciences (India)

Computational studies on energetic properties of nitrogen-rich energetic materials with ditetrazoles. LI XIAO-HONGa,b,∗ and ZHANG RUI-ZHOUa. aCollege of Physics and Engineering, Henan University of Science and Technology, Luoyang 471 003, China. bLuoyang Key Laboratory of Photoelectric Functional Materials, ...

The Energetics of Economics (Money as access to Energy)

OpenAIRE

Ternyik, Stephen I.

2013-01-01

Money is being portrayed as temporal access to energy and a new methodical approach to the energetics of the human economy is introduced.The economic evolution of world system energetics is put into the historical focus of all global monetary civilization, reaching back to Sumerian city states.This long wave energetics of human economic action clearly points to the biophysical boundaries of the globalized monetary production economy which is also based on natural law.The future perspective of...

Interaction in the large energetic companies in the Republic of Macedonia

International Nuclear Information System (INIS)

Janevski, Risto

1999-01-01

After disintegration of former power energetic system of Yugoslavia 1991, the Republic of Macedonia has faced enormous problems in the energetic field. It was necessary to realize all options in order to secure enough electric power for normal economic capacities function. In that course a direct involvement of five large companies, which represent very significant energetic subjects, will largely determine the future energetic conditions and circumstances in our country. These are the following companies: P.E. Electric Power Company Of Macedonia; OKTA Crude Oil Refinery; Heat Power Company; HEK Jugohrom; Fenimak. The paper presents the electric power consumption of these macro energetic companies during the period 1991-1998

Observations of Energetic Particle Escape at the Magnetopause: Early Results from the MMS Energetic Ion Spectrometer (EIS)

Science.gov (United States)

Cohen, I. J.; Mauk, B. H.; Anderson, B. J.; Westlake, J. H.; Sibeck, David Gary; Giles, Barbara L.; Pollock, C. J.; Turner, D. L.; Fennell, J. F.; Blake, J. B.;

Generation of pulsed far-infrared radiation and its application for far-infrared time-resolved spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kondo, Yasuhiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1996-07-01

So-called time-resolved spectroscopy technique has been used from old time as the means for studying the dynamic optical property, light-induced reaction and so on of matters. As an example, there is the method called pump and probe, and here, the wavelength of this probe light is the problem. If the object energy region is limited to about 0.1 eV, fast time-resolved spectroscopy is feasible relatively easily. However, energy region is extended to low energy region, the light source which is available as the pulsed probe light having sufficient intensity is limited. In this paper, the attempt of time-resolved spectroscopy utilizing coherent radiation, which has ended in failure, and the laser pulse-induced far-infrared radiation which can be utilized as new far-infrared probe light are reported. The reason why far-infrared radiation is used is explained. The attempt of time-resolved spectroscopy using NaCl crystals is reported on the equipment, the method of measuring absorption spectra and the results. Laser pulse-induced far-infrared radiation and the method of generating it are described. The multi-channel detector for far-infrared radiation which was made for trial is shown. (K.I.)

Quinquennial National Program (1990-1994) for the Energetic Modernization

International Nuclear Information System (INIS)

1990-01-01

The Mexican Energetics Sector currently has the eighth possition regarding reserves of hydrocarbons and the sixth regarding oil production, the installed capacity in electricity matters is among the first 20 of the world. The Program established first, a general balance of the situation in which the energetics sector lays today. It also points out the strategic role that this sector holds, as well an on the solutions to the problems faced. This Program establishes the objectives pursued by the energetics sector and that are as follows: to guarantee enough supply of energetics, to strenghten the link between the energetics sector and economy, society and environmental protection, to consolidate an energetics sector that is more current and better integrated. This Program presents the proposal to tend to five priorities: productivity, saving and effective use of energy, financing of the development and expansion of the offer, to diversify sources, as well as an efficient participation in international markets. In the chapter the effort regarding supply and demand of energy, it is evident that the effort made to expand the offer must be great, facing the total demand of energy demonstrated by the figures. For 1994 this demmand is of 31 - 36 % greater to that observed in 1988. Lastly, two statistic documents are enclosed, one historic, with general pointers of the sector, and another with the basic variables for national energy balance

The energetic significance of cooking.

Science.gov (United States)

Carmody, Rachel N; Wrangham, Richard W

2009-10-01

While cooking has long been argued to improve the diet, the nature of the improvement has not been well defined. As a result, the evolutionary significance of cooking has variously been proposed as being substantial or relatively trivial. In this paper, we evaluate the hypothesis that an important and consistent effect of cooking food is a rise in its net energy value. The pathways by which cooking influences net energy value differ for starch, protein, and lipid, and we therefore consider plant and animal foods separately. Evidence of compromised physiological performance among individuals on raw diets supports the hypothesis that cooked diets tend to provide energy. Mechanisms contributing to energy being gained from cooking include increased digestibility of starch and protein, reduced costs of digestion for cooked versus raw meat, and reduced energetic costs of detoxification and defence against pathogens. If cooking consistently improves the energetic value of foods through such mechanisms, its evolutionary impact depends partly on the relative energetic benefits of non-thermal processing methods used prior to cooking. We suggest that if non-thermal processing methods such as pounding were used by Lower Palaeolithic Homo, they likely provided an important increase in energy gain over unprocessed raw diets. However, cooking has critical effects not easily achievable by non-thermal processing, including the relatively complete gelatinisation of starch, efficient denaturing of proteins, and killing of food borne pathogens. This means that however sophisticated the non-thermal processing methods were, cooking would have conferred incremental energetic benefits. While much remains to be discovered, we conclude that the adoption of cooking would have led to an important rise in energy availability. For this reason, we predict that cooking had substantial evolutionary significance.

The influence of ion energy, target temperature, dose rate and crystal order on the shape of bombardment induced pyramids on copper crystals

International Nuclear Information System (INIS)

Tanovic, L.; Whitton, J.L.; Kofod, S.

1978-01-01

Following recent studies of energetic ion bombardment of copper, which established the conditions necessary for the production of cones/pyramids, investigations have been extended to include the effects of change in ion energy, target temperature and dose rate. In addition, the authors have attempted a detailed analysis of the influence of sample crystal orientation on the final form of pyramids and have investigated the stability of the pyramids as a function of the total dose. These experiments, as in earlier work, have been done using very pure copper, mass-analyzed ion beams and free of any metal contamination from, for example, defining apertures. (Auth.)

Sawteeth stabilization by energetic trapped ions

International Nuclear Information System (INIS)

Samain, A.; Edery, D.; Garbet, X.; Roubin, J.P.

1991-01-01

The analysis of a possible stabilization of sawteeth by a population of energetic ions is performed by using the Lagrangian of the electromagnetic perturbation. It is shown that the trapped component of such a population has a small influence compared to that of the passing component. The stabilization threshold is calculated assuming a non linear regime in the q=1 resonant layer. The energetic population must create a stable tearing structure if the average curvature effect on thermal particles in the layer is small. However, this effect decreases the actual threshold

Very energetic photons at HERA

International Nuclear Information System (INIS)

Bawa, A.C.; Krawczyk, M.

1991-01-01

We show that every energetic photons in the backward direction can be produced in deep inelastic Compton scattering at HERA. Assuming a fixed energy of 9 GeV for the initial photons and 820 GeV for the protons a high rate is found for the production of final photons with a transverse momentum equal to 5 GeV/c and energy between 40 GeV and 300 GeV. These energetic photons arise mainly from the scattering of the soft gluonic constituents of the initial photon with quarks from the proton. They are produced in the backward direction in coincidence with a photon beam jet of energy ∝ 9 GeV in the forward direction. (orig.)

The indexing ambiguity in serial femtosecond crystallography (SFX) resolved using an expectation maximization algorithm.

Science.gov (United States)

Liu, Haiguang; Spence, John C H

2014-11-01

Crystallographic auto-indexing algorithms provide crystal orientations and unit-cell parameters and assign Miller indices based on the geometric relations between the Bragg peaks observed in diffraction patterns. However, if the Bravais symmetry is higher than the space-group symmetry, there will be multiple indexing options that are geometrically equivalent, and hence many ways to merge diffraction intensities from protein nanocrystals. Structure factor magnitudes from full reflections are required to resolve this ambiguity but only partial reflections are available from each XFEL shot, which must be merged to obtain full reflections from these 'stills'. To resolve this chicken-and-egg problem, an expectation maximization algorithm is described that iteratively constructs a model from the intensities recorded in the diffraction patterns as the indexing ambiguity is being resolved. The reconstructed model is then used to guide the resolution of the indexing ambiguity as feedback for the next iteration. Using both simulated and experimental data collected at an X-ray laser for photosystem I in the P63 space group (which supports a merohedral twinning indexing ambiguity), the method is validated.

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources.

Science.gov (United States)

Rutherford, Michael E; Chapman, David J; White, Thomas G; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E

2016-05-01

The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

Pair creation by very high-energy photons in gamma-ray bursts a unified picture for the energetics of GRBs

CERN Document Server

Totani, T

1999-01-01

The extreme energetics of the gamma-ray burst (GRB) 990123 have revealed that some GRBs emit quite a large amount of energy, and the total energy release from GRBs seems to change from burst to burst by a factor of 10/sup 2/-10/sup $9 3/ as E/sub gamma , iso/~10/sup 52-55/ erg, where E/sub gamma , iso/ is the observed GRB energy when the radiation is isotropic. If all GRBs are triggered by similar events, such a wide dispersion in energy release seems odd. The $9 author proposes a unified picture for the energetics of GRBs, in which all GRB events release roughly the same amount of energy E/sub iso/~10 /sup 55-56/ erg relativistic motion, with the baryon load problem almost resolved. A mild $9 dispersion in the initial Lorentz factor ( Gamma ) results in a difference of E/sub gamma , iso/ by up to a factor of m/sub p//m/sub e/~10/sup 3/. Protons work as `a hidden energy reservoir' of the total GRB energy, and E/sub gamma , $9 iso/ depends on the energy transfer efficiency from protons into electrons (or posit...

Study of energetic dependence of LiF TLDs for photons

International Nuclear Information System (INIS)

Cavalieri, Tassio A.; Antunes, Paula C.G.; Paiva, Fabio; Branco, Isabela S.; Sena, Michelle K.S.; Siqueira, Paulo T.D.; Yoriyaz, Helio

2015-01-01

The LiF TLDs are widely used for photon dosimetry. However, in the most case the energetic dependence of these TLDs are not taken into account. This work is a preliminary study of energetic photon dependence in LiF TLD (TLD 700, enriched with 7 Li). For this study it was utilized a methodology already used in others works that seek understand the dependence energetic of TLD. It was utilized three different X-ray spectrum and a 137 Cs source; Beyond the calculus utilized in previous works, it was built the calibration curve for each spectrum to see the difference in dosimetry that the energetic dependence could cause. (author)

Study of energetic dependence of LiF TLDs for photons

Energy Technology Data Exchange (ETDEWEB)

Cavalieri, Tassio A.; Antunes, Paula C.G.; Paiva, Fabio; Branco, Isabela S.; Sena, Michelle K.S.; Siqueira, Paulo T.D.; Yoriyaz, Helio, E-mail: tcavalieri@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

The LiF TLDs are widely used for photon dosimetry. However, in the most case the energetic dependence of these TLDs are not taken into account. This work is a preliminary study of energetic photon dependence in LiF TLD (TLD 700, enriched with {sup 7}Li). For this study it was utilized a methodology already used in others works that seek understand the dependence energetic of TLD. It was utilized three different X-ray spectrum and a {sup 137}Cs source; Beyond the calculus utilized in previous works, it was built the calibration curve for each spectrum to see the difference in dosimetry that the energetic dependence could cause. (author)

Energetics Manufacturing Technology Center (EMTC)

Data.gov (United States)

Federal Laboratory Consortium — The Energetics Manufacturing Technology Center (EMTC), established in 1994 by the Office of Naval Research (ONR) Manufacturing Technology (ManTech) Program, is Navy...

High power laser research and development at the Laboratory for Laser Energetics

International Nuclear Information System (INIS)

Soures, J.M.; McCrory, R.L.; Cerqua, K.A.

1986-01-01

As part of its research mission - to investigate the interaction of intense radiation with matter - the Laboratory for Laser Energetics (LLE) of the University of Rochester is developing a number of high-peak power and high-average-power laser systems. In this paper we highlight some of the LLE work on solid-state laser research, development and applications. Specifically, we discuss the performance and operating characteristics of Omega, a twenty-four beam, 4000 Joule, Nd:glass laser system which is frequently tripled using the polarization mismatch scheme. We also discuss progress in efforts to develop high-average-power solid-state laser systems with active-mirror and slab geometries and to implement liquid-crystal devices in high-power Nd:glass lasers. Finally we present results from a program to develop a compact, ultrahigh-peak-power solid-state laser using the concept of frequency chirped pulse amplification

Energy and Biocides Storage Compounds: Synthesis and Characterization of Energetic Bridged Bis(triiodoazoles).

Science.gov (United States)

He, Chunlin; Zhao, Gang; Hooper, Joseph P; Shreeve, Jean'ne M

2017-11-06

Energetic bridged triiodopyrazoles and triiodoimidazoles were designed and synthsized by reacting potassium triiodopyrazolate or triiodoimidazolate with corresponding dichloro compounds. All compounds were fully characterized by 1 H and 13 C NMR spectroscopy, IR spectroscopy, and elemental analyses. The structure of compound 1 was further confirmed by single-crystal X-ray diffraction. All of the compounds exhibit good thermal stability with decomposition temperatures between 199 and 270 °C and high densities ranging from 2.804 to 3.358 g/cm 3 . The detonation performances and the detonation products were calculated by CHEETAH 7. Compound 3 (D v = 4765 m s -1 ; P = 17.9 GPa) and compound 7 (D v = 4841 m s -1 ; P = 18.5 GPa) show comparable detonation pressure to TNT, and high iodine content makes them promising as energy and biocides storage compounds.

Forecast of nuclear energetics

Energy Technology Data Exchange (ETDEWEB)

Sikora, W

1976-01-01

The forecast concerning the development of nuclear energetics is presented. Some information on economics of nuclear power plants is given. The nuclear fuel reserves are estimated on the background of power resources of the world. The safety and environment protection problems are mentioned.

Energetic particle pressure in intense ESP events

Science.gov (United States)

Lario, D.; Decker, R. B.; Roelof, E. C.; Viñas, A.-F.

2015-09-01

We study three intense energetic storm particle (ESP) events in which the energetic particle pressure PEP exceeded both the pressure of the background thermal plasma Pth and the pressure of the magnetic field PB. The region upstream of the interplanetary shocks associated with these events was characterized by a depression of the magnetic field strength coincident with the increase of the energetic particle intensities and, when plasma measurements were available, a depleted solar wind density. The general feature of cosmic-ray mediated shocks such as the deceleration of the upstream background medium into which the shock propagates is generally observed. However, for those shocks where plasma parameters are available, pressure balance is not maintained either upstream of or across the shock, which may result from the fact that PEP is not included in the calculation of the shock parameters.

Measuring the diffraction properties of an imaging quartz(211) crystal

Energy Technology Data Exchange (ETDEWEB)

Haugh, M. J.; Jacoby, K. D.; Koch, J. A. [National Security Technologies, LLC, Livermore, California 94550 (United States); Chen, H.; Schneider, M. B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Hill, K. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2016-06-15

A dual goniometer X-ray system was used to measure the reflectivity curve for a spherically bent quartz(211) crystal. An analysis of the dual goniometer instrument response function for the rocking curve width measurement was developed and tested against the actual measurements. The rocking curve was measured at 4510.8 eV using the Ti Kα1 characteristic spectral line. The crystal is the dispersion element for a high resolution spectrometer used for plasma studies. It was expected to have a very narrow rocking curve width. The analysis showed that we could measure the upper bound for the rocking curve width of the Qz(211) crystal. The upper bound was 58 μrad giving a lower bound for the instrument resolving power E/ΔE = 34 000. Greatly improved insight into the dual goniometer operation and its limitations was achieved.

Nuclear energy I, Non-energetic applications

International Nuclear Information System (INIS)

Lartigue G, J.; Navarrete T, M.; Cabrera M, L.; Arandia, P.A.; Arriola S, H.

1986-01-01

The nuclear energy is defined as the energy produced or absorbed in the nuclear reactions, therefore, these are divided in endothermic and exothermic. The exothermic nuclear reactions present more interest from the point of view of its applications and they can show in four main forms: radioactivity (from 0 to 4 MeV/reaction; light nucleus fusion ( ∼ 20 MeV/reaction), heavy nucleus fusion (∼ 200 MeV/reaction) and nucleons annihilation ( ∼ 2000 MeV/reaction). Nowadays only the fission has reached the stage of profitable energetic application, finding the other three forms in research and development. The non-energetic applications of the nuclear energy are characterized by they do not require of prior conversion to another form of energy and they are made through the use of radioisotopes as well as through the use of endothermic reaction caused in particle accelerators. In this work are presented some of the non-energetic applications with its theoretical and experimental basis as well as its benefits of each one. (Author)

Fibre Coupled Photonic Crystal Cavity Arrays on Transparent Substrates for Spatially Resolved Sensing

Directory of Open Access Journals (Sweden)

Mark G. Scullion

2014-11-01

Full Text Available We introduce a photonic crystal cavity array realised in a silicon thin film and placed on polydimethlysiloxane (PDMS as a new platform for the in-situ sensing of biomedical processes. Using tapered optical fibres, we show that multiple independent cavities within the same waveguide can be excited and their resonance wavelength determined from camera images without the need for a spectrometer. The cavity array platform combines sensing as a function of location with sensing as a function of time.

Picosecond laser pulse-driven crystallization behavior of SiSb phase change memory thin films

International Nuclear Information System (INIS)

Huang Huan; Li Simian; Zhai Fengxiao; Wang Yang; Lai Tianshu; Wu Yiqun; Gan Fuxi

2011-01-01

Highlights: → We reported crystallization dynamics of a novel SiSb phase change material. → We measured optical constants of as-deposited and irradiated SiSb areas. → Optical properties of as-deposited and irradiated SiSb thin film were compared. → Crystallization of irradiated SiSb was confirmed by using AFM and micro-Raman spectra. → The heat conduction effect of lower metal layer of multi-layer films was studied. - Abstract: Transient phase change crystallization process of SiSb phase change thin films under the irradiation of picosecond (ps) laser pulse was studied using time-resolved reflectivity measurements. The ps laser pulse-crystallized domains were characterized by atomic force microscope, Raman spectra and ellipsometrical spectra measurements. A reflectivity contrast of about 15% can be achieved by ps laser pulse-induced crystallization. A minimum crystallization time of 11 ns was achieved by a low-fluence single ps laser pulse after pre-irradiation. SiSb was shown to be very promising for fast phase change memory applications.

Structural and energetic characterization of anhydrous and hemihydrated 2-mercaptoimidazole: Calorimetric, X-ray diffraction, and computational studies

International Nuclear Information System (INIS)

Silva, Ana L.R.; Morais, Victor M.F.; Ribeiro da Silva, Maria D.M.C.; Simões, Ricardo G.; Bernardes, Carlos E.S.

2016-01-01

Highlights: • Rotating-bomb combustion calorimetry was used to obtain the enthalpy of formation of crystalline 2-mercaptoimidazole. • Enthalpy of sublimation of 2-mercaptoimidazole was measured by Calvet microcalorimetry. • Enthalpy of interaction between substituents is calculated using isodesmic reactions. • Crystal X-ray diffraction determinations for anhydrous and hemihydrate 2-mercaptoimidazole forms were carried. • Gas-phase enthalpies of formation of 2-mercaptoimidazole and 1,3-dihydro-2H-imidazole-2-thione estimated by the G3 method. - Abstract: This paper reports an experimental and theoretical study on the structural and energetic characterization of the 2-mercaptoimidazole (2-MI) in the solid and in the gaseous phases. The single crystal X-ray diffraction determinations on the anhydrous and hemihydrate 2-MI forms were carried out at T = (296 ± 2) K and T = (150 ± 2) K, respectively, and suggest that in both forms the 2-MI molecule is closer to the thione conformation, albeit some single bond character is possible. The energy of combustion of the title compound was measured by rotating-bomb combustion calorimetry, being used to derive the corresponding enthalpy of formation in the crystalline-phase. The enthalpy of sublimation of 2-MI, at T = 298.15 K, was obtained from high temperature Calvet microcalorimetry measurements. These two parameters yielded the gas-phase enthalpy of formation, allowing the inherent energetic analysis of the molecule. This result was discussed together with the corresponding predictions for 2-MI and its tautomer, 1,3-dihydro-2H-imidazole-2-thione, by the G3 method. The dehydration reaction of 2-MI · 0.5H_2O(cr) was also investigated and the corresponding enthalpy of dehydration was determined by Calvet microcalorimetry.

Time-resolved spectroscopy of nonequilibrium ionization in laser-produced plasmas

International Nuclear Information System (INIS)

Marjoribanks, R.S.

1988-01-01

The highly transient ionization characteristic of laser-produced plasmas at high energy densities has been investigated experimentally, using x-ray spectroscopy with time resolution of less than 20 ps. Spectroscopic diagnostics of plasma density and temperature were used, including line ratios, line profile broadening and continuum emission, to characterize the plasma conditions without relying immediately on ionization modeling. The experimentally measured plasma parameters were used as independent variables, driving an ionization code, as a test of ionization modeling, divorced from hydrodynamic calculations. Several state-of-the-art streak spectrographs, each recording a fiducial of the laser peak along with the time-resolved spectrum, characterized the laser heating of thin signature layers of different atomic numbers imbedded in plastic targets. A novel design of crystal spectrograph, with a conically curved crystal, was developed. Coupled with a streak camera, it provided high resolution (λ/ΔΛ > 1000) and a collection efficiency roughly 20-50 times that of planar crystal spectrographs, affording improved spectra for quantitative reduction and greater sensitivity for the diagnosis of weak emitters. Experimental results were compared to hydrocode and ionization code simulations, with poor agreement. The conclusions question the appropriateness of describing electron velocity distributions by a temperature parameter during the time of laser illumination and emphasis the importance of characterizing the distribution more generally

Energetic assessment of soybean biodiesel obtainment in West ...

African Journals Online (AJOL)

SAM

2014-07-16

Jul 16, 2014 ... Energetic outputs added up to 3,003.75 MJ and energy balance was 57,132.54 MJ. ... biodiesel, the study was divided into three stages: soybean farming, ... considering energetic consumptions with labor, seeds, diesel oil, ... model MF 283(4X2 TDA), power 63.2 kW (86 cv) in the engine, board weight.

Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasmas

International Nuclear Information System (INIS)

Du, X.D.; Toi, K.; Osakabe, M.

2014-10-01

A resistive interchange mode with bursting behavior and rapid frequency chirping in the range less than 10 kHz is observed for the first time in the magnetic hill region of net current-free, low beta LHD (Large Helical Device) plasmas during high power injection of perpendicular neutral beams. The mode resonates with the precession motion of helically trapped energetic beam ions, following the resonant condition. The radial mode structure is found to be very similar to that of usual pressure-driven interchange mode, of which radial displacement eigenfunction has an even function around the rational surface. This beam driven mode is excited when the beta value of helically trapped energetic ions exceed a certain threshold. The radial transport of helically trapped energetic ions induced by the mode transiently generates significant radial electric field near the plasma peripheral region. Thus generated radial electric field clearly suppresses micro turbulence and improves bulk plasma confinement, suggesting strong flow shear generation. (author)

Streaming reversal of energetic particles in the magnetotail during a substorm

Science.gov (United States)

Lui, A. T. Y.; Williams, D. J.; Eastman, T. E.; Frank, L. A.; Akasofu, S.-I.

1984-01-01

A case of reversal in the streaming anisotropy of energetic ions and in the plasma flow observed from the IMP 8 spacecraft during a substorm on February 8, 1978 is studied in detail using measurements of energetic particles, plasma, and magnetic field. Four new features emerge when high time resolution data are examined in detail. The times of streaming reversal of energetic particles in different energy ranges do not coincide with the time of plasma flow reversal. Qualitatively different velocity distributions are observed in earthward and tailward plasma flows during the observed flow reversal intervals. Strong tailward streaming of energetic particles can be detected during northward magnetic field environments and, conversely, earthward streaming in southward field environments. During the period of tailward streaming of energetic particles, earthward streaming fluxes are occasionally detected.

3D equilibrium crystal shapes in the new light of STM and AFM

International Nuclear Information System (INIS)

Bonzel, H.P.

2003-01-01

A systematic study of 3D equilibrium crystal shapes (ECS) can yield important surface energetic quantities, such as step, kink, surface and step-step interaction free energies. Observations of the ECS, especially of flat facets and adjacent vicinal regions, will provide primarily relative step and surface free energies. An advanced goal is to determine absolute step free energies, kink formation and step interaction energies. Absolute values of these energies are important in governing crystal growth morphologies, high temperature phase changes and kinetic processes associated with shape changes. Furthermore, absolute step and kink energies are the key to absolute surface free energies of well defined low-index orientations. We review new experiments where sections of the ECS are monitored as a function of temperature to extract characteristic morphological parameters, yielding absolute surface energetic quantities. Attention will be paid to the question of attaining true 3D equilibrium of an ensemble of crystallites. The special role of scanning tunneling and atomic force microscopies will be stressed. New ways of overcoming the problem of the activation barrier for facet growth (or shrinkage) through the study of dislocated crystallites will be demonstrated. In the general context of 3D crystallites, the study of 2D nano-crystals, in the form of adatom or vacancy islands on extended flat surfaces, will be discussed. In particular, the connection between the temperature dependent shape of 2D islands and the absolute step and kink formation energies of the bounding steps, complementary to facet shape changes of 3D crystallites, has emerged as an important topic of recent research. Finally, high temperature phase changes, such as surface roughening and surface melting, as they have been observed by scanning electron microscopy on 3D crystallites, will be briefly reviewed

Energetic Ion Loss Diagnostic for the Wendelstein 7-AS Stellarator

International Nuclear Information System (INIS)

Darrow, D. S.; Werner, A.; Weller, A.

2000-01-01

A diagnostic to measure the loss of energetic ions from the Wendelstein 7-AS (W7-AS) stellarator has been built. It is capable of measuring losses of both neutral beam ions and energetic ions arising from ion cyclotron resonant heating. The probe can measure losses of both clockwise and counterclockwise-going energetic ions simultaneously, and accepts a wide range of pitch angles in both directions. Initial measurements by the diagnostic are reported

Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas

Energy Technology Data Exchange (ETDEWEB)

Chen, Liu [Univ. of California, Irvine, CA (United States)

2017-12-20

This report summarizes major theoretical findings in the linear as well as nonlinear physics of Alfvén waves and energetic particles in magnetically confined fusion plasmas. On the linear physics, a variational formulation, based on the separation of singular and regular spatial scales, for drift-Alfvén instabilities excited by energetic particles is established. This variational formulation is then applied to derive the general fishbone-like dispersion relations corresponding to the various Alfvén eigenmodes and energetic-particle modes. It is further employed to explore in depth the low-frequency Alfvén eigenmodes and demonstrate the non-perturbative nature of the energetic particles. On the nonlinear physics, new novel findings are obtained on both the nonlinear wave-wave interactions and nonlinear wave-energetic particle interactions. It is demonstrated that both the energetic particles and the fine radial mode structures could qualitatively affect the nonlinear evolution of Alfvén eigenmodes. Meanwhile, a theoretical approach based on the Dyson equation is developed to treat self-consistently the nonlinear interactions between Alfvén waves and energetic particles, and is then applied to explain simulation results of energetic-particle modes. Relevant list of journal publications on the above findings is also included.

Spatially resolved micro-Raman observation on the phase separation of effloresced sea salt droplets.

Science.gov (United States)

Xiao, Han-Shuang; Dong, Jin-Ling; Wang, Liang-Yu; Zhao, Li-Jun; Wang, Feng; Zhang, Yun-Hong

2008-12-01

We report on the investigation of the phase separation of individual seawater droplets in the efflorescence processes with the spatially resolved Raman system. Upon decreasing the relative humidity (RH), CaSO4.0.5H2O separated out foremost fromthe droplet atan unexpectedly high RH of approcimately 90%. Occasionally, CaSO4.2H2O substituted for CaSO4.O.5H2O crystallizing first at approximately 78% RH. Relatively large NaCI solids followed to crystallize at approximately 55% RH and led to the great loss of the solution. Then, the KMgCl3.6H2O crystallites separated out from the residual solutions, adjacentto NaCl at approximately 44% RH. Moreover, a shell structure of dried sea salt particle was found to form at low RHs, with the NaCl crystals in the core and minor supersaturated solutions covered with MgSO4 gel coating on the surface. Ultimately, the shielded solution partly effloresced into MgSO4 hydrates at very dry state (<5% RH).

Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

International Nuclear Information System (INIS)

Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

2005-01-01

We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This work provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum optics in photonic-band-gap crystals and for applications wherein directional emission and total emission power are controlled

Atomic motion of resonantly vibrating quartz crystal visualized by time-resolved X-ray diffraction

International Nuclear Information System (INIS)

Aoyagi, Shinobu; Osawa, Hitoshi; Sugimoto, Kunihisa; Fujiwara, Akihiko; Takeda, Shoichi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

2015-01-01

Transient atomic displacements during a resonant thickness-shear vibration of AT-cut α-quartz are revealed by time-resolved X-ray diffraction under an alternating electric field. The lattice strain resonantly amplified by the alternating electric field is ∼10 4 times larger than that induced by a static electric field. The resonantly amplified lattice strain is achieved by fast displacements of oxygen anions and collateral resilient deformation of Si−O−Si angles bridging rigid SiO 4 tetrahedra, which efficiently transduce electric energy into elastic energy

Energetic charged particles above thunderclouds

International Nuclear Information System (INIS)

Fullekrug, Martin; Diver, Declan; Pincon, Jean-Louis; Renard, Jean-Baptiste; Phelps, Alan D.R.; Bourdon, Anne; Helling, Christiane; Blanc, Elisabeth; Honary, Farideh; Kosch, Mike; Harrison, Giles; Sauvaud, Jean-Andre; Lester, Mark; Rycroft, Michael; Kosch, Mike; Horne, Richard B.; Soula, Serge; Gaffet, Stephane

2013-01-01

The French government has committed to launch the satellite TARANIS to study transient coupling processes between the Earth's atmosphere and near-Earth space. The prime objective of TARANIS is to detect energetic charged particles and hard radiation emanating from thunderclouds. The British Nobel prize winner C. T. R. Wilson predicted lightning discharges from the top of thunderclouds into space almost a century ago. However, new experiments have only recently confirmed energetic discharge processes which transfer energy from the top of thunderclouds into the upper atmosphere and near-Earth space; they are now denoted as transient luminous events, terrestrial gamma-ray flashes and relativistic electron beams. This meeting report builds on the current state of scientific knowledge on the physics of plasmas in the laboratory and naturally occurring plasmas in the Earth's atmosphere to propose areas of future research. The report specifically reflects presentations delivered by the members of a novel Franco-British collaboration during a meeting at the French Embassy in London held in November 2011. The scientific subjects of the report tackle ionization processes leading to electrical discharge processes, observations of transient luminous events, electromagnetic emissions, energetic charged particles and their impact on the Earth's atmosphere. The importance of future research in this area for science and society, and towards spacecraft protection, is emphasized. (authors)

Compton polarimetry with position-resolving X-ray detectors

International Nuclear Information System (INIS)

Hess, Sebastian

2010-02-01

In the present thesis the prototype of a novel position-resolving and multi-hit able 2D Si(Li) strip detector is characterized, the planar detector crystal of which is simultaneously applied both as scatterer and as absorber. In the framework of this thesis the Si(Li) polarimeter could be applied in different experiments on the radiative electron capture and on the characteristic radiation at the experimental storage ring of the GSI. The characterization of the detector pursued by means of the highly polarized radiation of the electron capture into the K shell of naked xenon. In the following in two further experiments new values on the polarization of the electron capture into the K shell both of the naked and of the hydrogen-like uranium were performed.

Random laser action in stoichiometric Nd3Ga5O12 garnet crystal powder

International Nuclear Information System (INIS)

Iparraguirre, I; Azkargorta, J; Barredo-Zuriarrain, M; Balda, R; Fernández, J; Kamada, K; Yoshikawa, A; Rodríguez-Mendoza, U R; Lavín, V

2016-01-01

This work explores the room temperature infrared random laser (RL) performance of Nd 3+ ions in a new stoichiometric Nd 3 Ga 5 O 12 crystal powder. The time-resolved measurements show that the RL pulse is able to follow the subnanosecond oscillations of the pump pulse profile. The pump threshold energy and the absolute stimulated emission energy have been measured using a method developed by the authors. The laser slope efficiency is the highest compared to other Nd 3+ stoichiometric RL crystals. (letter)

Bulk crystal growth and electronic characterization of the 3D Dirac semimetal Na3Bi

Directory of Open Access Journals (Sweden)

Satya K. Kushwaha

2015-04-01

Full Text Available High quality hexagon plate-like Na3Bi crystals with large (001 plane surfaces were grown from a molten Na flux. The freshly cleaved crystals were analyzed by low temperature scanning tunneling microscopy and angle-resolved photoemission spectroscopy, allowing for the characterization of the three-dimensional (3D Dirac semimetal (TDS behavior and the observation of the topological surface states. Landau levels were observed, and the energy-momentum relations exhibited a linear dispersion relationship, characteristic of the 3D TDS nature of Na3Bi. In transport measurements on Na3Bi crystals, the linear magnetoresistance and Shubnikov-de Haas quantum oscillations are observed for the first time.

Electrical resistance of flaky crystals in the longitudinal quantizing magnetic field

International Nuclear Information System (INIS)

Askerov, B.M.; Figarova, S.R.; Makhmudov, M.M.

2005-01-01

Specific resistance of the quasi-two-dimensional electrical gas in the longitudinal quantizing magnetic field is investigated in this work. Common expression for resistivity in the flaky crystals was received. In quantum limit was analyzed dependence of the resistivity from the size of magnetic field and parameters energetic spectra in case of strong degenerate gas. It was tagged that, the conduct of specific resistance is formed by the dependence of chemical potential from the size of magnetic field. At the defined value of the chemical potential and size of magnetic field obtains inflation of the specific resistance. (author)

Energetic lanthanide complexes: coordination chemistry and explosives applications

International Nuclear Information System (INIS)

Manner, V W; Barker, B J; Sanders, V E; Laintz, K E; Scott, B L; Preston, D N; Sandstrom, M; Reardon, B L

2014-01-01

Metals are generally added to organic molecular explosives in a heterogeneous composite to improve overall heat and energy release. In order to avoid creating a mixture that can vary in homogeneity, energetic organic molecules can be directly bonded to high molecular weight metals, forming a single metal complex with Angstrom-scale separation between the metal and the explosive. To probe the relationship between the structural properties of metal complexes and explosive performance, a new series of energetic lanthanide complexes has been prepared using energetic ligands such as NTO (5-nitro-2,4-dihydro-1,2,4-triazole-3-one). These are the first examples of lanthanide NTO complexes where no water is coordinated to the metal, demonstrating novel control of the coordination environment. The complexes have been characterized by X-ray crystallography, NMR and IR spectroscopies, photoluminescence, and sensitivity testing. The structural and energetic properties are discussed in the context of enhanced blast effects and detection. Cheetah calculations have been performed to fine-tune physical properties, creating a systematic method for producing explosives with 'tailor made' characteristics. These new complexes will be benchmarks for further study in the field of metalized high explosives.

Alignment and experiment of the HL-1 X-ray bent-crystal spectrometer

International Nuclear Information System (INIS)

Chen Jiefu; Yuan Chengji; Zhang Shuxun; Lu Jie; Yie Gaoying; Zhang Li

1993-04-01

An X-ray bent-crystal spectrometer, which is developed by Southwestern Institute of Physics, has been aligned and experimental on the HL-1 Tokamak device. It has been used to acquire experimental spectrum. This spectrometer has time resolution function and is a high through-put and high resolution Bragg crystal spectrometer with Johann configuration. It uses a large quartz lamina, its effective area is 11 x 5 cm 2 , with a radius of curvature of 377 cm as the dispersion element. The detector is a large size (10 x 10 cm 2 ) one-dimensional resolving multiwire proportional counter, and the spectral resolving power is R ≅ 18000. Under the injection of Ar into hydrogen plasma, the He-like Ar ion satellite spectra at some wavelength ranges are obtained. The central ion temperature has been given out from the Doppler broadening of He-like Ar x VII 3.9457 angstrom resonance line. This shows the success of spectrometer developed. The experimental results and the further improvement of this spectrometer are also discussed

Biogas - energetical and environmental point of view

International Nuclear Information System (INIS)

Skele, A.; Upitis, A.; Kristapsons, M.; Goizevskis, O.; Ziemelis, I.

2003-01-01

Energy sector has been one of the most important priorities since reestablishment of independence of Latvia. The deficiency of energy resources in Latvia has created a need to assess all the possibilities to utilise all possibilities to utilise all the energy resources, including the biological ones, to motivate the trends in the development of energetic in Latvia. A huge non-utilised reserve in Latvia is methane fermentation of organic agricultural and municipal residue and sewage from food industry. The organic mass of solid and liquid waste of different origin and its energetic potential for rural region have been investigated. The work deals with an integrated system of the utilisation of agricultural waste with the anaerobic (biogas) and the thermal processes. Presently the anaerobic waste utilisation, in combination with the production of biogas and organic fertiliser, is considered as one of the energetically most efficient and environment-friendly ways of organic fertiliser utilisation (authors)

Propagation of biochirality: crossovers and nonclassical crystallization kinetics of aspartic acid in water.

Science.gov (United States)

Lee, Tu; Lin, Yu Kun; Tsai, Ya Chung; Lee, Hung Lin

2013-11-01

All experimental procedures discussed could be treated as a screening tool for probing the existence of molecular association among the chiral molecules and the solvent system. The molecular association phases of a racemic conglomerate solution (CS) and a racemic compound solution (RCS), and the templating effect of aspartic acid solid surface were observed to minimize the chance of redissolving racemic conglomerate and racemic compound aspartic acid in water and reforming an RCS in crossovers experiments. Only 1 %wt% of l-aspartic acid was adequate enough to induce a transformation from a racemic compound aspartic acid to a racemic conglomerate aspartic acid. This would make the propagation of biochirality more feasible and sound. However, tetrapeptide, (l-aspartic acid)4 , failed to induce enantioseparation as templates purely by crystallization. Nonclassical crystallization theory was needed to take into account the existence of a CS. Fundamental parameters of the crystallization kinetics such as the induction time, interfacial energy, Gibbs energetic barrier, nucleation rate, and critical size of stable nuclei of: (i) racemic compound aspartic acid, (ii) racemic compound aspartic acid seeded with 1 %wt% l-aspartic acid, (iii) racemic conglomerate aspartic acid, and (iv) l-aspartic acid were evaluated and compared with different initial supersaturation ratios. Morphological studies of crystals grown from the crystallization kinetics were also carried out. © 2013 Wiley Periodicals, Inc.

Imaging of THz waves in 2D photonic crystal structures embedded in a slab waveguide

International Nuclear Information System (INIS)

Peier, P; Merbold, H; Feurer, T; Pahinin, V; Nelson, K A

2010-01-01

We present space- and time-resolved simulations and measurements of single-cycle terahertz (THz) waves propagating through two-dimensional (2D) photonic crystal structures embedded in a slab waveguide. Specifically, we use a plane wave expansion technique to calculate the band structure and a time-dependent finite-element method to simulate the temporal evolution of the THz waves. Experimentally, we measure the space-time evolution of the THz waves through a coherent time-resolved imaging method. Three different structures are laser machined in LiNbO 3 crystal slabs and analyzing the transmitted as well as the reflected THz waveforms allows determination of the bandgaps. Comparing the results with the calculated band diagrams and the time-dependent simulations shows that the experiments are consistent with 3D simulations, which include the slab waveguide geometry, the birefringence of the material, and a careful analysis of the excited modes within the band diagrams.

Determining the diffraction properties of a cylindrically bent KAP(001) crystal from 1 to 5 keV

Energy Technology Data Exchange (ETDEWEB)

Haugh, Michael [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Lee, Joshua [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Jacoby, Kenneth [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Christensen, C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Loisel, G. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States), Livermore Operations

2015-08-31

Various crystals are used for the dispersive component of X-ray spectrometers. The crystals are usually bent to meet the desired measurement needs, such as focusing. The bending can change the crystal diffraction properties, thus altering the spectrometer throughput and resolving power. This work concerns measuring the diffraction properties of a potassium acid phthalate (001) [KAP(001)] crystal bent into a circular cylinder segment. The measurement methods using a diode source and a synchrotron source are described. The multi-lamellar model for calculating the diffraction properties of a bent crystal is described. The measurement results are compared to the multi-lamellar model and show qualitative agreement. The measurements show how to make the multi-lamellar calculations a useful estimate. A method is given to make useful estimates of the diffraction properties of the KAP(001) crystal bent into a circular cylinder segment.

Measuring the critical resolved shear stresses in Mg alloys by instrumented nanoindentation

International Nuclear Information System (INIS)

Sánchez-Martín, R.; Pérez-Prado, M.T.; Segurado, J.; Bohlen, J.; Gutiérrez-Urrutia, I.; Llorca, J.; Molina-Aldareguia, J.M.

2014-01-01

One of the main limiting factors in the development of new magnesium (Mg) alloys with enhanced mechanical behavior is the need to use vast experimental campaigns for microstructure and property screening. For example, the influence of new alloying additions on the critical resolved shear stresses (CRSSs) is currently evaluated by a combination of macroscopic single-crystal experiments and crystal plasticity finite-element simulations (CPFEM). This time-consuming process could be considerably simplified by the introduction of high-throughput techniques for efficient property testing. The aim of this paper is to propose a new and fast, methodology for the estimation of the CRSSs of hexagonal close-packed metals which, moreover, requires small amounts of material. The proposed method, which combines instrumented nanoindentation and CPFEM modeling, determines CRSS values by comparison of the variation of hardness (H) for different grain orientations with the outcome of CPFEM. This novel approach has been validated in a rolled and annealed pure Mg sheet, whose H variation with grain orientation has been successfully predicted using a set of CRSSs taken from recent crystal plasticity simulations of single-crystal experiments. Moreover, the proposed methodology has been utilized to infer the effect of the alloying elements of an MN11 (Mg–1% Mn–1% Nd) alloy. The results support the hypothesis that selected rare earth intermetallic precipitates help to bring the CRSS values of basal and non-basal slip systems closer together, thus contributing to the reduced plastic anisotropy observed in these alloys

Color centers in heavily irradiated CsI(Tl) crystals

International Nuclear Information System (INIS)

Yakovlev, V.; Meleshko, A.; Trefilova, L.

2008-01-01

The absorption and luminescence properties of CsI(Tl) crystals colored by irradiation are studied by the method of the time-resolved spectroscopy. The scheme of the electron transitions in CsI(Tl) crystal is suggested to explain the appearance of the color centers under exposure to the near-UV light. It is established that either of the two types activator color centers holds the charge carrier with opposite sign. The model of the hole Tl 2+ v c - activator color center is suggested. According to the model the positive charge of Tl 2+ ion is compensated by the negative charge of a close cation vacancy v c - . The color center emission reveals in the cathode-luminescence spectrum of the colored CsI(Tl) crystal. The high-dose irradiation of CsI(Tl) crystal results in the reduction of the decay time of the near-thallium self-trapped excitons (STE) emission. The decay kinetics of Tl 2+ v c - emission contains the time components typical for the decay kinetics of near-thallium STE emission. The reason of the observed effects is the energy transfer from the near-thallium STE excitons to the color centers via the inductive-resonant mechanism

Energetic ions and electrons and their acceleration processes in the magnetotail

International Nuclear Information System (INIS)

Scholer, M.

1984-01-01

Observations of energetic particle fluxes in the geomagnetic tail show that these particles exhibit a bursty appearance on all time scales. Often, however, the bursty appearance is merely due to multiple entries and exits of the spacecraft into and out of the plasma sheet which always contains varying fluxes of energetic particles. Observations of the suprathermal and high-energy component of the plasma sheet are discussed, and observations are presented of energetic particle bursts in the plasma sheet proper, which may be due to a locally ongoing acceleration process. Also discussed are energetic particle phenomena occurring near the edge of the plasma sheet, either during thinning or during recovery. Some recent results from the ISEE 3 deep tail mission bearing on energetic particle acceleration are presented, and the present status of the theory of particle acceleration within the magnetotail is briefly reviewed. 40 references

Recent progress of hybrid simulation for energetic particles and MHD

International Nuclear Information System (INIS)

Todo, Y.

2013-01-01

Several hybrid simulation models have been constructed to study the evolution of Alfven eigenmodes destabilized by energetic particles. Recent hybrid simulation results of energetic particle driven instabilities are presented in this paper. (J.P.N.)

Direct observation of spin-resolved full and empty electron states in ferromagnetic surfaces

Energy Technology Data Exchange (ETDEWEB)

Berti, G., E-mail: giulia.berti@polimi.it; Calloni, A.; Brambilla, A.; Bussetti, G.; Duò, L.; Ciccacci, F. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy)

2014-07-15

We present a versatile apparatus for the study of ferromagnetic surfaces, which combines spin-polarized photoemission and inverse photoemission spectroscopies. Samples can be grown by molecular beam epitaxy and analyzed in situ. Spin-resolved photoemission spectroscopy analysis is done with a hemispherical electron analyzer coupled to a 25 kV-Mott detector. Inverse photoemission spectroscopy experiments are performed with GaAs crystals as spin-polarized electron sources and a UV bandpass photon detector. As an example, measurements on the oxygen passivated Fe(100)-p(1×1)O surface are presented.

Determination of electronic states in crystalline semiconductors and metals by angle-resolved photoemission

International Nuclear Information System (INIS)

Mills, K.A.

1979-08-01

An important part of the theoretical description of the solid state is band structure, which relies on the existence of dispersion relations connecting the electronic energy and wavevector in materials with translational symmetry. These relations determine the electronic behavior of such materials. The elaboration of accurate band structures, therefore, is of considerable fundamental and practical importance. Angle-resolved photoemission (ARP) spectroscopy provides the only presently available method for the detailed experimental investigation of band structures. This work is concerned with its application to both semiconducting and metallic single crystals

Direct determination of exciton wavefunction amplitudes by the momentum-resolved photo-electron emission experiment

Science.gov (United States)

Ohnishi, Hiromasa; Tomita, Norikazu; Nasu, Keiichiro

2018-03-01

We study conceptional problems of a photo-electron emission (PEE) process from a free exciton in insulating crystals. In this PEE process, only the electron constituting the exciton is suddenly emitted out of the crystal, while the hole constituting the exciton is still left inside and forced to be recoiled back to its original valence band. This recoil on the hole is surely reflected in the spectrum of the PEE with a statistical distribution along the momentum-energy curve of the valence band. This distribution is nothing but the square of the exciton wavefunction amplitude, since it shows how the electron and the hole are originally bound together. Thus, the momentum-resolved PEE can directly determine the exciton wavefunction. These problems are clarified, taking the Γ and the saddle point excitons in GaAs, as typical examples. New PEE experiments are also suggested.

Internal Transport Barrier Driven by Redistribution of Energetic Ions

International Nuclear Information System (INIS)

Wong, K.L.; Heidbrink, W.W.; Ruskov, E.; Petty, C.C.; Greenfield, C.M.; Nazikian, R.; Budny, R.

2004-01-01

Alfven instabilities excited by energetic ions are used as a means to reduce the central magnetic shear in a tokamak via redistribution of energetic ions. When the central magnetic shear is low enough, ballooning modes become stable for any plasma pressure gradient and an internal transport barrier (ITB) with a steep pressure gradient can exist. This mechanism can sustain a steady-state ITB as demonstrated by experimental data from the DIII-D tokamak. It can also produce a shear in toroidal and poloidal plasma rotation. Possible application of this technique to use the energetic alpha particles for improvement of burning plasma performance is discussed

Dynamic transition in the structure of an energetic crystal during chemical reactions at shock front prior to detonation.

Science.gov (United States)

Nomura, Ken-Ichi; Kalia, Rajiv K; Nakano, Aiichiro; Vashishta, Priya; van Duin, Adri C T; Goddard, William A

2007-10-05

Mechanical stimuli in energetic materials initiate chemical reactions at shock fronts prior to detonation. Shock sensitivity measurements provide widely varying results, and quantum-mechanical calculations are unable to handle systems large enough to describe shock structure. Recent developments in reactive force-field molecular dynamics (ReaxFF-MD) combined with advances in parallel computing have paved the way to accurately simulate reaction pathways along with the structure of shock fronts. Our multimillion-atom ReaxFF-MD simulations of l,3,5-trinitro-l,3,5-triazine (RDX) reveal that detonation is preceded by a transition from a diffuse shock front with well-ordered molecular dipoles behind it to a disordered dipole distribution behind a sharp front.

Grotthuss Transport of Iodide in EMIM/I3 Ionic Crystal.

Science.gov (United States)

McDaniel, Jesse G; Yethiraj, Arun

2018-01-11

Highly ionic environments can mediate unusual chemical reactions that would otherwise be considered impossible based on chemical intuition. For example, the formation of a chemical bond between two iodide anions to form a divalent polyiodide anion is seemingly prohibited due to Coulombic repulsion. Using ab initio molecular dynamics simulations, we show that in the 1-ethyl-3-methylimidazolium (EMIM)/I 3 ionic crystal, the reactive formation of divalent and even trivalent polyiodide anions occurs with extremely small energetic barriers, due to the electrostatic field of the ionic lattice. A practical consequence of this anomalous reactivity is that iodide anions are efficiently transported within the crystal through a "Grotthuss-exchange" mechanism involving bond-breaking and forming events. We characterize two distinct transport pathways, involving both I 4 2- and I 7 3- intermediates, with fast transport of iodide resulting from the release of an I - anion on the opposite side of the intermediate species from the initial bond formation. The ordered cation arrangement in the crystal provides the necessary electrostatic screening for close approach of anions, suggesting a new counterintuitive approach to obtain high ionic conductivity. This new design principle could be used to develop better solid-state electrolytes for batteries, fuel cells, and supercapacitors.

Energetic Particles: From Sun to Heliosphere - and vice versa

Science.gov (United States)

Wimmer-Schweingruber, R. F.; Rodriguez-Pacheco, J.; Boden, S.; Boettcher, S. I.; Cernuda, I.; Dresing, N.; Drews, C.; Droege, W.; Espinosa Lara, F.; Gomez-Herrero, R.; Heber, B.; Ho, G. C.; Klassen, A.; Kulkarni, S. R.; Mann, G. J.; Martin-Garcia, C.; Mason, G. M.; Panitzsch, L.; Prieto, M.; Sanchez, S.; Terasa, C.; Eldrum, S.

2017-12-01

Energetic particles in the heliosphere can be measured at their elevated energetic status after three processes: injection, acceleration, and transport. Suprathermal seed particles have speeds well above the fast magnetosonic speed in the solar wind frame of reference and can vary from location to location and within the solar activity cycle. Acceleration sites include reconnecting current sheets in solar flares or magnetspheric boundaries, shocks in the solar corona, heliosphere and a planetary obstacles, as well as planetary magnetospheres. Once accelerated, particles are transported from the acceleration site into and through the heliosphere. Thus, by investigating properties of energetic particles such as their composition, energy spectra, pitch-angle distribution, etc. one can attempt to distinguish their origin or injection and acceleration site. This in turn allows us to better understand transport effects whose underlying microphysics is also a key ingredient in the acceleration of particles. In this presentation we will present some clear examples which link energetic particles from their observing site to their source locations. These include Jupiter electrons, singly-charged He ions from CIRs, and 3He from solar flares. We will compare these examples with the measurement capabilities of the Energetic Particle Detector (EPD) on Solar Orbiter and consider implications for the key science goal of Solar Orbiter and Solar Proble Plus - How the Sun creates and controls the heliosphere.

Optical Investigation of Nanoconfined Crystal Growth

Science.gov (United States)

Kohler, F.; Dysthe, D. K.

2015-12-01

Crystals growing in a confined space exert forces on their surroundings. This crystallization force causes deformation of solids and is therefore particularly relevant for the comprehension of geological processes such as replacement and weathering [1]. In addition, these forces are relevant for the understanding of damages in porous building materials caused by crystallization, which is of great economical importance and fundamental for methods that can help to preserve our cultural heritage [2,3]. However, the exact behavior of the growth and the dissolution process in close contact to an interface are still not known in detail. The crystallization, the dissolution and the transport of material is mediated by a nanoconfined water film. We observe brittle NaClO3 crystals growing against a glass surface by optical methods such as reflective interference contrast microscopy (RICM) [4]. In order to carefully control the supersaturation of the fluid close to the crystal interface, a temperature regulated microfluidic system is used (fig. A). The interference based precision of RICM enables to resolve distance variations down to the sub nanometer range without any unwanted disturbances by the measuring method. The combination of RICM with a sensitive camera allows us to observe phenomena such as periodic, wavelike growth of atomic layers. These waves are particularly obvious when observing the difference between two consecutive images (fig. B). In contradiction to some theoretical results, which predict a smooth interface, some recent experiments have shown that the nanoconfined growth surfaces are rough. In combination with theoretical studies and Kinetic Monte Carlo simulations we aim at providing more realistic descriptions of surface energies and energy barriers which are able to explain the discrepancies between experiments and current theory. References:[1] Maliva, Diagenetic replacement controlled by force of crystallization, Geology, August (1988), v. 16 [2] G

Energy transfer between the Eu2+ dipole and aggregate centers in CsBr:Eu crystals

International Nuclear Information System (INIS)

Zorenko, Yu.; Turchak, R.; Voznjak, T.

2007-01-01

The energy transfer between the Eu 2+ -V Cs dipole centers and presumable CsEuBr 3 aggregate centers has been studied in CsBr:Eu crystals by means of investigation of their time-resolved emission spectra and luminescence decay kinetics at 300 K

The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite.

Science.gov (United States)

Rodriguez-Blanco, Juan Diego; Shaw, Samuel; Benning, Liane G

2011-01-01

The kinetics and mechanisms of nanoparticulate amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range of environmentally relevant temperatures (7.5-25 °C) using synchrotron-based in situ time-resolved Energy Dispersive X-ray Diffraction (ED-XRD) in conjunction with high-resolution electron microscopy, ex situ X-ray diffraction and infrared spectroscopy. The crystallization process occurs in two stages; firstly, the particles of ACC rapidly dehydrate and crystallize to form individual particles of vaterite; secondly, the vaterite transforms to calcite via a dissolution and reprecipitation mechanism with the reaction rate controlled by the surface area of calcite. The second stage of the reaction is approximately 10 times slower than the first. Activation energies of calcite nucleation and crystallization are 73±10 and 66±2 kJ mol(-1), respectively. A model to calculate the degree of calcite crystallization from ACC at environmentally relevant temperatures (7.5-40 °C) is also presented.

A simple approach to spectrally resolved fluorescence and bright field microscopy over select regions of interest

OpenAIRE

Dahlberg, Peter D.; Boughter, Christopher T.; Faruk, Nabil F.; Hong, Lu; Koh, Young Hoon; Reyer, Matthew A.; Shaiber, Alon; Sherani, Aiman; Zhang, Jiacheng; Jureller, Justin E.; Hammond, Adam T.

2016-01-01

A standard wide field inverted microscope was converted to a spatially selective spectrally resolved microscope through the addition of a polarizing beam splitter, a pair of polarizers, an amplitude-mode liquid crystal-spatial light modulator, and a USB spectrometer. The instrument is capable of simultaneously imaging and acquiring spectra over user defined regions of interest. The microscope can also be operated in a bright-field mode to acquire absorption spectra of micron scale objects. Th...

Growth, Faraday and inverse Faraday characteristics of Tb2Ti2O7 crystal.

Science.gov (United States)

Guo, Feiyun; Sun, Yilin; Yang, Xiongsheng; Chen, Xin; Zhao, Bin; Zhuang, Naifeng; Chen, Jianzhong

2016-03-21

Tb2Ti2O7 (TTO) single crystal with dimensions of 20 × 20 × 16 mm3 was grown by the Czochralski method. Rietveld structure refinement of X-ray diffraction (XRD) data confirms that the compound crystallizes in the cubic system with pyrochlore structure. Transmission spectra, Magnetic circular dichroism (MCD) spectra, Faraday and inverse Faraday characteristics of TTO crystal have been measured and analyzed in detail. The results demonstrate that TTO crystal has high transmittance at 700-1400 nm waveband and a larger Verdat constant than that of TGG reported. Magnetic circular dichroism (MCD) spectra showed that the 4f→4f transitions of Tb3+ have significant contributions to the magneto-optical activity (MOA). In the time-resolved pump-probe spectroscopy, the rotation signals of the probe beam based on the inverse Faraday effect in magneto-optical crystal were observed at zero time delay, the full width at half maximum of the rotation and ellipticity signals can be as fast as ~500 fs, which indicates that TTO crystal can be a promising material for ultrafast all-optical magnetic switching.

Energetics of dislocation transformations in hcp metals

International Nuclear Information System (INIS)

Wu, Zhaoxuan; Yin, Binglun; Curtin, W.A.

2016-01-01

Dislocation core structures of hcp metals are highly complex and differ significantly among the hcp family. Some dislocations undergo unconventional transformations that have significant effects on the material plastic flow. Here, the energetics of dislocation dissociations are analyzed in a general anisotropic linear elastic theory framework for transformations in which changes in the partial Burgers vectors are small. Quantitative analyses on various transformations are made using DFT-computed stacking fault energies and partial Burgers vectors. Specifically, possible transformations of the mixed, edge, and screw 〈c+a〉 and screw 〈a〉 dislocations in 6 hcp metals (Mg, Ti, Zr, Re, Zn, Cd) are studied. Climb dissociation of mixed or edge 〈c+a〉 dislocations to the Basal plane is energetically favorable in all 6 metals and thus only limited by thermal activation. The 〈c+a〉 screw dislocation is energetically preferable on Pyramidal I for Ti, Zr, and Re, and on Pyramidal II for Zn and Cd. In Mg, the energy difference between screw 〈c+a〉 on Pyramidal I and II planes is small, suggesting relatively easy cross-slip. For the screw 〈a〉, Basal dissociation is energetically favorable in Mg, Re, Zn and Cd, while Prism dissociation is strongly favorable in Ti and Zr. Only Ti, Zr and Re show a metastable state for dissociation on the Prism plane, and the energy difference between screw 〈a〉 on the Prism and Pyramidal I planes is relatively small in all systems, suggesting relatively easy cross-slip of 〈a〉 in Ti and Zr. The elastic analysis thus provides a single framework able to capture the controlling energetics for different dissociations and slip systems in hcp metals. When the calculated energy differences are very small, the results point to the need for detailed modeling of the atomistic core structure. Moreover, the analyses rationalize broad experimental observations on dominant slip systems and dislocation behaviours, and provide

Full melting of a two-dimensional complex plasma crystal triggered by localized pulsed laser heating

Science.gov (United States)

Couëdel, L.; Nosenko, V.; Rubin-Zuzic, M.; Zhdanov, S.; Elskens, Y.; Hall, T.; Ivlev, A. V.

2018-04-01

The full melting of a two-dimensional plasma crystal was induced in a principally stable monolayer by localized laser stimulation. Two distinct behaviors of the crystal after laser stimulation were observed depending on the amount of injected energy: (i) below a well-defined threshold, the laser melted area recrystallized; (ii) above the threshold, it expanded outwards in a similar fashion to mode-coupling instability-induced melting, rapidly destroying the crystalline order of the whole complex plasma monolayer. The reported experimental observations are due to the fluid mode-coupling instability, which can pump energy into the particle monolayer at a rate surpassing the heat transport and damping rates in the energetic localized melted spot, resulting in its further growth. This behavior exhibits remarkable similarities with impulsive spot heating in ordinary reactive matter.

Investigation of energetic particle induced geodesic acoustic mode

Science.gov (United States)

Schneller, Mirjam; Fu, Guoyong; Chavdarovski, Ilija; Wang, Weixing; Lauber, Philipp; Lu, Zhixin

2017-10-01

Energetic particles are ubiquitous in present and future tokamaks due to heating systems and fusion reactions. Anisotropy in the distribution function of the energetic particle population is able to excite oscillations from the continuous spectrum of geodesic acoustic modes (GAMs), which cannot be driven by plasma pressure gradients due to their toroidally and nearly poloidally symmetric structures. These oscillations are known as energetic particle-induced geodesic acoustic modes (EGAMs) [G.Y. Fu'08] and have been observed in recent experiments [R. Nazikian'08]. EGAMs are particularly attractive in the framework of turbulence regulation, since they lead to an oscillatory radial electric shear which can potentially saturate the turbulence. For the presented work, the nonlinear gyrokinetic, electrostatic, particle-in-cell code GTS [W.X. Wang'06] has been extended to include an energetic particle population following either bump-on-tail Maxwellian or slowing-down [Stix'76] distribution function. With this new tool, we study growth rate, frequency and mode structure of the EGAM in an ASDEX Upgrade-like scenario. A detailed understanding of EGAM excitation reveals essential for future studies of EGAM interaction with micro-turbulence. Funded by the Max Planck Princeton Research Center. Computational resources of MPCDF and NERSC are greatefully acknowledged.

Time-resolved soft x-ray absorption setup using multi-bunch operation modes at synchrotrons

International Nuclear Information System (INIS)

Stebel, L.; Sigalotti, P.; Ressel, B.; Cautero, G.; Malvestuto, M.; Capogrosso, V.; Bondino, F.; Magnano, E.; Parmigiani, F.

2011-01-01

Here, we report on a novel experimental apparatus for performing time-resolved soft x-ray absorption spectroscopy in the sub-ns time scale using non-hybrid multi-bunch mode synchrotron radiation. The present setup is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ∼500 MHz x-ray synchrotron radiation bunches and on a detection system that discriminates and singles out the significant x-ray photon pulses by means of a custom made photon counting unit. The whole setup has been validated by measuring the time evolution of the L 3 absorption edge during the melting and the solidification of a Ge single crystal irradiated by an intense ultrafast laser pulse. These results pave the way for performing synchrotron time-resolved experiments in the sub-ns time domain with variable repetition rate exploiting the full flux of the synchrotron radiation.

The synthesis of di(aminoguanidine) 5-nitroiminotetrazolate: some diprotic or monoprotic acids as precursors of energetic salts.

Science.gov (United States)

Gao, Haixiang; Huang, Yangen; Ye, Chengfeng; Twamley, Brendan; Shreeve, Jean'ne M

2008-01-01

Syntheses of salts with 4,6-bis(nitroimino)-1,3,5-triazinan-2-one (DNAM), 3,5-dinitro-1,2,4-cyclopentanetrione (DDCP), 3-nitroiminotriazolate, and 5-nitroiminotetrazolate as anions yielded moderately dense nitro-containing energetic salts that are thermally stable to >200 degrees C (measured by thermogravimetric analysis). Di(aminoguanidine) 5-nitroiminotetrazolate (8) crystallizes in the monoclinic space group P2(1)/c with an essentially planar 5-nitroiminotetrazolate dianion. Based on experimental and calculated densities, and theoretical calculations carried out by using the Gaussian 03 suite of programs, all of the salts have calculated detonation pressures and velocities that exceed those of 2,4,6-trinitrotoluene (TNT) and a few have values that approach those of triaminotrinitrobenzene (TATB).

Comparison of approximations in density functional theory calculations: Energetics and structure of binary oxides

Science.gov (United States)

Hinuma, Yoyo; Hayashi, Hiroyuki; Kumagai, Yu; Tanaka, Isao; Oba, Fumiyasu

2017-09-01

High-throughput first-principles calculations based on density functional theory (DFT) are a powerful tool in data-oriented materials research. The choice of approximation to the exchange-correlation functional is crucial as it strongly affects the accuracy of DFT calculations. This study compares performance of seven approximations, six of which are based on Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) with and without Hubbard U and van der Waals corrections (PBE, PBE+U, PBED3, PBED3+U, PBEsol, and PBEsol+U), and the strongly constrained and appropriately normed (SCAN) meta-GGA on the energetics and crystal structure of elementary substances and binary oxides. For the latter, only those with closed-shell electronic structures are considered, examples of which include C u2O , A g2O , MgO, ZnO, CdO, SnO, PbO, A l2O3 , G a2O3 , I n2O3 , L a2O3 , B i2O3 , Si O2 , Sn O2 , Pb O2 , Ti O2 , Zr O2 , Hf O2 , V2O5 , N b2O5 , T a2O5 , Mo O3 , and W O3 . Prototype crystal structures are selected from the Inorganic Crystal Structure Database (ICSD) and cation substitution is used to make a set of existing and hypothetical oxides. Two indices are proposed to quantify the extent of lattice and internal coordinate relaxation during a calculation. The former is based on the second invariant and determinant of the transformation matrix of basis vectors from before relaxation to after relaxation, and the latter is derived from shifts of internal coordinates of atoms in the unit cell. PBED3, PBEsol, and SCAN reproduce experimental lattice parameters of elementary substances and oxides well with few outliers. Notably, PBEsol and SCAN predict the lattice parameters of low dimensional structures comparably well with PBED3, even though these two functionals do not explicitly treat van der Waals interactions. SCAN gives formation enthalpies and Gibbs free energies closest to experimental data, with mean errors (MEs) of 0.01 and -0.04 eV, respectively, and root

Analysis and verification of a prediction model of solar energetic proton events

Science.gov (United States)

Wang, J.; Zhong, Q.

2017-12-01

The solar energetic particle event can cause severe radiation damages near Earth. The alerts and summary products of the solar energetic proton events were provided by the Space Environment Prediction Center (SEPC) according to the flux of the greater than 10 MeV protons taken by GOES satellite in geosynchronous orbit. The start of a solar energetic proton event is defined as the time when the flux of the greater than 10 MeV protons equals or exceeds 10 proton flux units (pfu). In this study, a model was developed to predict the solar energetic proton events, provide the warning for the solar energetic proton events at least minutes in advance, based on both the soft X-ray flux and integral proton flux taken by GOES. The quality of the forecast model was measured against verifications of accuracy, reliability, discrimination capability, and forecast skills. The peak flux and rise time of the solar energetic proton events in the six channels, >1MeV, >5 MeV, >10 MeV, >30 MeV, >50 MeV, >100 MeV, were also simulated and analyzed.

Dual scattering foil design for poly-energetic electron beams

International Nuclear Information System (INIS)

Kainz, K K; Antolak, J A; Almond, P R; Bloch, C D; Hogstrom, K R

2005-01-01

The laser wakefield acceleration (LWFA) mechanism can accelerate electrons to energies within the 6-20 MeV range desired for therapy application. However, the energy spectrum of LWFA-generated electrons is broad, on the order of tens of MeV. Using existing laser technology, the therapeutic beam might require a significant energy spread to achieve clinically acceptable dose rates. The purpose of this work was to test the assumption that a scattering foil system designed for a mono-energetic beam would be suitable for a poly-energetic beam with a significant energy spread. Dual scattering foil systems were designed for mono-energetic beams using an existing analytical formalism based on Gaussian multiple-Coulomb scattering theory. The design criterion was to create a flat beam that would be suitable for fields up to 25 x 25 cm 2 at 100 cm from the primary scattering foil. Radial planar fluence profiles for poly-energetic beams with energy spreads ranging from 0.5 MeV to 6.5 MeV were calculated using two methods: (a) analytically by summing beam profiles for a range of mono-energetic beams through the scattering foil system, and (b) by Monte Carlo using the EGS/BEAM code. The analytic calculations facilitated fine adjustments to the foil design, and the Monte Carlo calculations enabled us to verify the results of the analytic calculation and to determine the phase-space characteristics of the broadened beam. Results showed that the flatness of the scattered beam is fairly insensitive to the width of the input energy spectrum. Also, results showed that dose calculated by the analytical and Monte Carlo methods agreed very well in the central portion of the beam. Outside the useable field area, the differences between the analytical and Monte Carlo results were small but significant, possibly due to the small angle approximation. However, these did not affect the conclusion that a scattering foil system designed for a mono-energetic beam will be suitable for a poly-energetic

Moessbauer determination of magnetic structure of Fe3BO6 crystal

International Nuclear Information System (INIS)

Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

1984-01-01

The magnetic structure of a Fe 3 BO 6 crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer γ-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV γ-quanta from the Fe 3 BO 6 monocrystal has been studied experimentally. A high sensitivity of the interference of γ-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe 3 BO 6 . Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail

Inferring repeat-protein energetics from evolutionary information.

Directory of Open Access Journals (Sweden)

Rocío Espada

2017-06-01

Full Text Available Natural protein sequences contain a record of their history. A common constraint in a given protein family is the ability to fold to specific structures, and it has been shown possible to infer the main native ensemble by analyzing covariations in extant sequences. Still, many natural proteins that fold into the same structural topology show different stabilization energies, and these are often related to their physiological behavior. We propose a description for the energetic variation given by sequence modifications in repeat proteins, systems for which the overall problem is simplified by their inherent symmetry. We explicitly account for single amino acid and pair-wise interactions and treat higher order correlations with a single term. We show that the resulting evolutionary field can be interpreted with structural detail. We trace the variations in the energetic scores of natural proteins and relate them to their experimental characterization. The resulting energetic evolutionary field allows the prediction of the folding free energy change for several mutants, and can be used to generate synthetic sequences that are statistically indistinguishable from the natural counterparts.

Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules.

Science.gov (United States)

Hendriks, Frank C; Schmidt, Joel E; Rombouts, Jeroen A; Lammertsma, Koop; Bruijnincx, Pieter C A; Weckhuysen, Bert M

2017-05-05

A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent mapping of the resulting fluorescence using confocal fluorescence microscopy reveal differences in structural integrity: the 90° intergrowth sections of MFI crystals are prone to develop structural imperfections, which act as entrance routes for the probes into the zeolite crystal. Polarization-dependent measurements provide evidence for the probe molecule's alignment within the MFI zeolite pore system. The developed method was extended to BEA (Beta) crystals, showing that the previously observed hourglass pattern is a general feature of BEA crystals with this morphology. Furthermore, the probes can accurately identify at which crystal faces of BEA straight or sinusoidal pores open to the surface. The results show this method can spatially resolve the architecture-dependent internal pore structure of microporous materials, which is difficult to assess using other characterization techniques such as X-ray diffraction. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Theoretical modeling of zircon's crystal morphology according to data of atomistic calculations

Science.gov (United States)

Gromalova, Natalia; Nikishaeva, Nadezhda; Eremin, Nikolay

2017-04-01

Zircon is an essential mineral that is used in the U-Pb dating. Moreover, zircon is highly resistant to radioactive exposure. It is of great interest in solving both fundamental and applied problems associated with the isolation of high-level radioactive waste. There is significant progress in forecasting of the most energetically favorable crystal structures at the present time. Unfortunately, the theoretical forecast of crystal morphology at high technological level is under-explored nowadays, though the estimation of crystal equilibrium habit is extremely important in studying the physical and chemical properties of new materials. For the first time, the thesis about relation of the equilibrium shape of a crystal with its crystal structure was put forward in the works by O.Brave. According to it, the idealized habit is determined in the simplest case by a correspondence with the reticular densities Rhkl of individual faces. This approach, along with all subsequent corrections, does not take into account the nature of atoms and the specific features of the chemical bond in crystals. The atomistic calculations of crystal surfaces are commonly performed using the energetic characteristics of faces, namely, the surface energy (Esurf), which is a measure of the thermodynamic stability of the crystal face. The stable crystal faces are characterized by small positive values of Esurf. As we know from our previous research (Gromalova et al.,2015) one of the constitutive factors affecting the value of the surface energy in calculations is a choice of potentials model. In this regard, we studied several sets of parameters of atomistic interatomic potentials optimized previously. As the first test model («Zircon 1») were used sets of interatomic potentials of interaction Zr-O, Si-O and O-O in the form of Buckingham potentials. To improve playback properties of zircon additionally used Morse potential for a couple of Zr-Si, as well as the three-particle angular harmonic

Low temperature deformation mechanisms in LiF single crystals

International Nuclear Information System (INIS)

Fotedar, H.L.; Stroebe, T.G.

1976-01-01

An analysis of the deformation behavior of high purity LiF single crystals is given using yielding and work hardening data and thermally activated deformation parameters obtained in the temperature range 77-423 0 K. It is found that while the Fleischer mechanism is apparently valid experimentally over the thermally activated temperature range, vacancies produced in large numbers at 77 0 K could also play a role in determining the critical resolved shear stress at that temperature

3D imaging of intrinsic crystalline defects in zinc oxide by spectrally resolved two-photon fluorescence microscopy

Science.gov (United States)

Al-Tabich, A.; Inami, W.; Kawata, Y.; Jablonski, R.; Worasawat, S.; Mimura, H.

2017-05-01

We present a method for three-dimensional intrinsic defect imaging in zinc oxide (ZnO) by spectrally resolved two-photon fluorescence microscopy, based on the previously presented method of observing a photoluminescence distribution in wide-gap semiconductor crystals [Noor et al., Appl. Phys. Lett. 92(16), 161106 (2008)]. A tightly focused light beam radiated by a titanium-sapphire laser is used to obtain a two-photon excitation of selected area of the ZnO sample. Photoluminescence intensity of a specific spectral range is then selected by optical band pass filters and measured by a photomultiplier tube. Reconstruction of the specimen image is done by scanning the volume of interest by a piezoelectric positioning stage and measuring the spectrally resolved photoluminescence intensity at each point. The method has been proved to be effective at locating intrinsic defects of the ZnO crystalline structure in the volume of the crystal. The method was compared with other defect imaging and 3D imaging techniques like scanning tunneling microscopy and confocal microscopy. In both cases, our method shows superior penetration abilities and, as the only method, allows location of the defects of the chosen type in 3D. In this paper, we present the results of oxygen vacancies and zinc antisites imaging in ZnO nanorods.

Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals

Energy Technology Data Exchange (ETDEWEB)

Armas-Pérez, Julio C. [Institute; División; Li, Xiao [Institute; Martínez-González, José A. [Institute; Smith, Coleman [Institute; Hernández-Ortiz, J. P. [Departamento; Nealey, Paul F. [Institute; Materials; de Pablo, Juan J. [Institute; Materials

2017-08-17

Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal. To do so, we adopt a tensorial description of the free energy of the hybrid liquidcrystal surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.

Modeling Thermal Ignition of Energetic Materials

National Research Council Canada - National Science Library

Gerri, Norman J; Berning, Ellen

2004-01-01

This report documents an attempt to computationally simulate the mechanics and thermal regimes created when a threat perforates an armor envelope and comes in contact with stowed energetic material...

Energetic adaptations persist after bariatric surgery in severely obese adolescents

Science.gov (United States)

Energetic adaptations induced by bariatric surgery have not been studied in adolescents or for extended periods postsurgery. Energetic, metabolic, and neuroendocrine responses to Roux-en-Y gastric bypass (RYGB) surgery were investigated in extremely obese adolescents. At baseline and at 1.5, 6, and...

Effect of Trapped Energetic Ions on MHD Activity in Spherical Tori

International Nuclear Information System (INIS)

White, R.B.; Kolesnichenko, Ya.I.; Lutsenko, V.V.; Marchenko, V.S.

2002-01-01

It is shown that the increase of beta (the ratio of plasma pressure to the magnetic field pressure) may change the character of the influence of trapped energetic ions on MHD stability in spherical tori. Namely, the energetic ions, which stabilize MHD modes (such as the ideal-kink mode, collisionless tearing mode, and semi-collisional tearing mode) at low beta, have a destabilizing influence at high beta unless the radial distribution of the energetic ions is very peaked

The HZE radiation problem. [highly-charged energetic galactic cosmic rays

Science.gov (United States)

Schimmerling, Walter

1990-01-01

Radiation-exposure limits have yet to be established for missions envisioned in the framework of the Space Exploration Initiative. The radiation threat outside the earth's magnetosphere encompasses protons from solar particle events and the highly charged energetic particles constituting galactic cosmic rays; radiation biology entails careful consideration of the extremely nonuniform patterns of such particles' energy deposition. The ability to project such biological consequences of exposure to energetic particles as carcinogenicity currently involves great uncertainties from: (1) different regions of space; (2) the effects of spacecraft structures; and (3) the dose-effect relationships of single traversals of energetic particles.

Convergence behavior of idealized convection-resolving simulations of summertime deep moist convection over land

Science.gov (United States)

Panosetti, Davide; Schlemmer, Linda; Schär, Christoph

2018-05-01

Convection-resolving models (CRMs) can explicitly simulate deep convection and resolve interactions between convective updrafts. They are thus increasingly used in numerous weather and climate applications. However, the truncation of the continuous energy cascade at scales of O (1 km) poses a serious challenge, as in kilometer-scale simulations the size and properties of the simulated convective cells are often determined by the horizontal grid spacing (Δ x ).In this study, idealized simulations of deep moist convection over land are performed to assess the convergence behavior of a CRM at Δ x = 8, 4, 2, 1 km and 500 m. Two types of convergence estimates are investigated: bulk convergence addressing domain-averaged and integrated variables related to the water and energy budgets, and structural convergence addressing the statistics and scales of individual clouds and updrafts. Results show that bulk convergence generally begins at Δ x =4 km, while structural convergence is not yet fully achieved at the kilometer scale, despite some evidence that the resolution sensitivity of updraft velocities and convective mass fluxes decreases at finer resolution. In particular, at finer grid spacings the maximum updraft velocity generally increases, and the size of the smallest clouds is mostly determined by Δ x . A number of different experiments are conducted, and it is found that the presence of orography and environmental vertical wind shear yields more energetic structures at scales much larger than Δ x , sometimes reducing the resolution sensitivity. Overall the results lend support to the use of kilometer-scale resolutions in CRMs, despite the inability of these models to fully resolve the associated cloud field.

Interaction in the large energetics companies in the Republic of Macedonia (Part 3)

International Nuclear Information System (INIS)

Janevski, Risto

2000-01-01

After the disintegration of former power energetic system of Yugoslavia 1991, the Republic of Macedonia has faced enormous problems in the energetic field. It was necessary to realize all options in order to secure enough electric power for normal economic capacities function. In that course a direct involvement of five large companies, which represent very significant energetic subjects, will largely determine the future energetic conditions and circumstances in our country. These are the following companies: P.E. Electric Power Co. of Macedonia; Heat Power Co.; HEK Jugohrom; Fenimak. In this paper the energetic system of the OKTA Crude Oil Refinery from 1991-1998 is analyzed, as well as its characteristics and plans for the future development

Streaming reversal of energetic particles in the magnetetail during a substorm

International Nuclear Information System (INIS)

Lui, A.T.Y.; Williams, D.J.; Eastman, T.E.; Frank, L.A.; Akasofu, S.

1984-01-01

Reversal from tailward streaming to earthward streaming of energetic ions at 0.29--0.50 MeV during a substorm on February 3, 1978, is studied with measurements of energetic particles, plasma, and magnetic field from that IMP 8 spacecraft near the dusk flank of the magnetotail. Four new features emerge when high time resolution data are examined in detail. The times of reversal from tailward to earthward streaming of energetic ions and from tailward to earthward plasma flow do not coincide. Second, the velocity distribution in the tailward flowing plasma has a cresent shape, whereas the velocity distribution in the earthward flowing plasma has a crescent shape, whereas the velocity distribution in the earthward flowing plasma resembles a convecting Maxwellian. Third, tailward streaming of energetic ions is sometime detected in northward magnetic field regions and conversely, earthward streaming in southward field environments. Fourth, energetic ions scattering earthward are occasionally present in conjunction with a strong tailward streaming population in the same energy range. These new features suggest that the streaming reversal of energetic ions and the plasma flow reversal in this event are due to the spacecraft traversing different plasma regions during the substorm-associated configurational change of the plasma sheet and the magnetotail and is unrelated to the motion of an acceleration region such as an X type neutral line moving past the spacecraft

Response of Seven Crystallographic Orientations of Sapphire Crystals to Shock Stresses of 16 to 86 GPa

OpenAIRE

Kanel, G. I.; Nellis, W. J.; Savinykh, A. S.; Razorenov, S. V.; Rajendran, A. M.

2009-01-01

Shock-wave profiles of sapphire (single-crystal Al2O3) with seven crystallographic orientations were measured with time-resolved VISAR interferometry at shock stresses in the range 16 to 86 GPa. Shock propagation was normal to the surface of each cut. The angle between the c-axis of the hexagonal crystal structure and the direction of shock propagation varied from 0 for c-cut up to 90 degrees for m-cut in the basal plane. Based on published shock-induced transparencies, shock-induced optical ...

Energetics, Biomechanics, and Performance in Masters' Swimmers: A Systematic Review.

Science.gov (United States)

Ferreira, Maria I; Barbosa, Tiago M; Costa, Mário J; Neiva, Henrique P; Marinho, Daniel A

2016-07-01

Ferreira, MI, Barbosa, TM, Costa, MJ, Neiva, HP, and Marinho, DA. Energetics, biomechanics, and performance in masters' swimmers: a systematic review. J Strength Cond Res 30(7): 2069-2081, 2016-This study aimed to summarize evidence on masters' swimmers energetics, biomechanics, and performance gathered in selected studies. An expanded search was conducted on 6 databases, conference proceedings, and department files. Fifteen studies were selected for further analysis. A qualitative evaluation of the studies based on the Quality Index (QI) was performed by 2 independent reviewers. The studies were thereafter classified into 3 domains according to the reported data: performance (10 studies), energetics (4 studies), and biomechanics (6 studies). The selected 15 articles included in this review presented low QI scores (mean score, 10.47 points). The biomechanics domain obtained higher QI (11.5 points), followed by energetics and performance (10.6 and 9.9 points, respectively). Stroke frequency (SF) and stroke length (SL) were both influenced by aging, although SF is more affected than SL. Propelling efficiency (ηp) decreased with age. Swimming performance declined with age. The performance declines with age having male swimmers deliver better performances than female counterparts, although this difference tends to be narrow in long-distance events. One single longitudinal study is found in the literature reporting the changes in performance over time. The remaining studies are cross-sectional designs focusing on the energetics and biomechanics. Overall, biomechanics parameters, such as SF, SL, and ηp, tend to decrease with age. This review shows the lack of a solid body of knowledge (reflected in the amount and quality of the articles published) on the changes in biomechanics, energetics, and performance of master swimmers over time. The training programs for this age-group should aim to preserve the energetics as much as possible and, concurrently, improve the

{CoIII2DyIII2} single molecule magnet with two resolved thermal activated magnetization relaxation pathways at zero field.

Science.gov (United States)

Funes, Alejandro V; Carrella, Luca; Rentschler, Eva; Alborés, Pablo

2014-02-14

The new complex [Co(III)2Dy(III)2(OMe)2(teaH)2(Piv)6] in the {Co(III)2Dy(III)2} family, shows two well resolved thermal activated magnetization relaxation pathways under AC experiments in zero DC field. Fitted crystal field parameters suggest that the origin of these two pathways relies on two different excited mJ sub-levels.

Atypical energetic particle events observed prior energetic particle enhancements associated with corotating interaction regions

Science.gov (United States)

Khabarova, Olga; Malandraki, Olga; Zank, Gary; Jackson, Bernard; Bisi, Mario; Desai, Mihir; Li, Gang; le Roux, Jakobus; Yu, Hsiu-Shan

2017-04-01

Recent studies of mechanisms of particle acceleration in the heliosphere have revealed the importance of the comprehensive analysis of stream-stream interactions as well as the heliospheric current sheet (HCS) - stream interactions that often occur in the solar wind, producing huge magnetic cavities bounded by strong current sheets. Such cavities are usually filled with small-scale magnetic islands that trap and re-accelerate energetic particles (Zank et al. ApJ, 2014, 2015; le Roux et al. ApJ, 2015, 2016; Khabarova et al. ApJ, 2015, 2016). Crossings of these regions are associated with unusual variations in the energetic particle flux up to several MeV/nuc near the Earth's orbit. These energetic particle flux enhancements called "atypical energetic particle events" (AEPEs) are not associated with standard mechanisms of particle acceleration. The analysis of multi-spacecraft measurements of energetic particle flux, plasma and the interplanetary magnetic field shows that AEPEs have a local origin as they are observed by different spacecraft with a time delay corresponding to the solar wind propagation from one spacecraft to another, which is a signature of local particle acceleration in the region embedded in expanding and rotating background solar wind. AEPEs are often observed before the arrival of corotating interaction regions (CIRs) or stream interaction regions (SIRs) to the Earth's orbit. When fast solar wind streams catch up with slow solar wind, SIRs of compressed heated plasma or more regular CIRs are created at the leading edge of the high-speed stream. Since coronal holes are often long-lived structures, the same CIR re-appears often for several consecutive solar rotations. At low heliographic latitudes, such CIRs are typically bounded by forward and reverse waves on their leading and trailing edges, respectively, that steepen into shocks at heliocentric distances beyond 1 AU. Energetic ion increases have been frequently observed in association with CIR

Resolving the Framework Position of Organic Structure-Directing Agents in Hierarchical Zeolites via Polarized Stimulated Raman Scattering.

Science.gov (United States)

Fleury, Guillaume; Steele, Julian A; Gerber, Iann C; Jolibois, F; Puech, P; Muraoka, Koki; Keoh, Sye Hoe; Chaikittisilp, Watcharop; Okubo, Tatsuya; Roeffaers, Maarten B J

2018-04-05

The direct synthesis of hierarchically intergrown silicalite-1 can be achieved using a specific diquaternary ammonium agent. However, the location of these molecules in the zeolite framework, which is critical to understand the formation of the material, remains unclear. Where traditional characterization tools have previously failed, herein we use polarized stimulated Raman scattering (SRS) microscopy to resolve molecular organization inside few-micron-sized crystals. Through a combination of experiment and first-principles calculations, our investigation reveals the preferential location of the templating agent inside the linear pores of the MFI framework. Besides illustrating the attractiveness of SRS microscopy in the field of material science to study and spatially resolve local molecular distribution as well as orientation, these results can be exploited in the design of new templating agents for the preparation of hierarchical zeolites.

Radiational and energetic characteristics of diatomic molecules (data base)

International Nuclear Information System (INIS)

Kuznetsova, L.A.; Pazyuk, E.A.; Stolyarov, A.V.

1993-01-01

Data base on radiational and energetic characteristics of diatomic molecules was created. The base consists of two parts: reference system and recommended data system. The reference system contains the information about studies of radiational and energetic parameters of more than 1500 electronic states and 1700 electron transfers for ∼ 350 diatomic molecules and their ions. The base bibliography includes ∼ 3000 publications. 11 refs., 1 figs

Gas-liquid reactive crystallization kinetics of 2,4,6-triamino-1,3,5-trinitrobenzene in the semi-batch procedure

Science.gov (United States)

Liu, Ruqin; Huang, Ming; Yao, Xiaolu; Chen, Shuang; Wang, Shucun; Suo, Zhirong

2018-06-01

2,4,6-Triamino-1,3,5-trinitrobenzene is the attractive insensitive high energetic material used extensively in the military and civil fields. Combined with the double-films theory, the global gas-liquid chemical reaction kinetics of 2,4,6-triamino-1,3,5-trinitrobenzene was developed by means of the infinitesimal material balance calculation. The raw material concentration and reactive temperature effects on the crystallization of 2,4,6-triamino-1,3,5-trinitrobenzene were investigated by the batch experiments. The reactive crystallization kinetics associated ammonia feeding rate of 2,4,6-triamino-1,3,5-trinitrobenzene, including nucleation as well as crystal growth, was systematically investigated in the heterogonous semi-batch procedure. The nucleation and crystal growth kinetic exponents were estimated by the linear least-squares method. The crystallization kinetic results indicated that nucleation rate strongly increased but liner growth rate decreased with the increasing of ammonia feeding rate. In terms of manufacturing coarse 2,4,6-triamino-1,3,5-trinitrobenzene, it was found that a slow ammonia feeding rate and a low raw material concentration were feasible under the present experimental conditions.

Energetic cost of communication.

Science.gov (United States)

Stoddard, Philip K; Salazar, Vielka L

2011-01-15

Communication signals may be energetically expensive or inexpensive to produce, depending on the function of the signal and the competitive nature of the communication system. Males of sexually selected species may produce high-energy advertisement signals, both to enhance detectability and to signal their size and body condition. Accordingly, the proportion of the energy budget allocated to signal production ranges from almost nothing for many signals to somewhere in excess of 50% for acoustic signals in short-lived sexually selected species. Recent data from gymnotiform electric fish reveal mechanisms that regulate energy allocated to sexual advertisement signals through dynamical remodeling of the excitable membranes in the electric organ. Further, males of the short-lived sexually selected species, Brachyhypopomus gauderio, trade off among different metabolic compartments, allocating energy to signal production while reducing energy used in other metabolic functions. Female B. gauderio, by contrast, do not trade off energy between signaling and other functions. To fuel energetically expensive signal production, we expect a continuum of strategies to be adopted by animals of different life history strategies. Future studies should explore the relation between life history and energy allocation trade-offs.

Stabilized super-thermite colloids: A new generation of advanced highly energetic materials

Science.gov (United States)

Elbasuney, Sherif; Gaber Zaky, M.; Radwan, Mostafa; Mostafa, Sherif F.

2017-10-01

One of the great impetus of nanotechnology on energetic materials is the achievement of nanothermites (metal-oxide/metal) which are characterized by massive heat output. Yet, full exploitation of super-thermites in highly energetic systems has not been achieved. This manuscript reports on the sustainable fabrication of colloidal Fe2O3 and CuO nanoparticles for thermite applications. TEM micrographs demonstrated mono-dispersed Fe2O3 and CuO with an average particle size of 3 and 15 nm respectively. XRD diffractograms demonstrated highly crystalline materials. SEM micrographs demonstrated a great tendency of the developed oxides to aggregate over drying process. The effective integration and dispersion of mono-dispersed colloidal thermite particles into energetic systems are vital for enhanced performance. Aluminum is of interest as highly energetic metal fuel. In this paper, synthesized Fe2O3 and CuO nanoparticles were re-dispersed in isopropyl alcohol (IPA) with aluminum nanoparticles using ultrasonic prope homogenizer. The colloidal thermite peraticles can be intgegrated into highly energetic system for subsequent nanocomposite development. Thanks to stabilization of colloidal CuO nanoparticles in IPA which could offer intimate mixing between oxidizer and metal fuel. The stabilization mechanism of CuO in IPA was correlated to steric stabilization with solvent molecules. This approach eliminated nanoparticle drying and the re-dispersion of dry aggregates into energetic materials. This manuscript shaded the light on the real development of colloidal thermite mixtures and their integration into highly energetic systems.

Plastic deformation of Ni3Nb single crystals

International Nuclear Information System (INIS)

Hagihara, Kouji; Nakano, Takayoshi; Umakoshi, Yukichi

1999-01-01

Temperature dependence of yield stress and operative slip system in Ni 3 Nb single crystals with the D0 a structure was investigated in comparison with that in an analogous L1 2 structure. Compression tests were performed at temperatures between 20 C and 1,200 C for specimens with loading axes perpendicular to (110), (331) and (270). (010)[100] slip was operative for three orientations, while (010)[001] slip for (331) and [211] twin for (270) orientations were observed, depending on deformation temperature. The critical resolved shear stress (CRSS) for the (010)[100] slip anomaly increased with increasing temperature showing a maximum peak between 400 C and 800 C depending on crystal orientation. The CRSS showed orientation dependence and no significant strain rate dependence in the temperature range for anomalous strengthening. The [100] dislocations with a screw character were aligned on the straight when the anomalous strengthening occurred. The anomalous strengthening mechanism for (010)[100] slip in Ni 3 Nb single crystals is discussed on the basis of a cross slip model which has been widely accepted for some L1 2 -type compounds

Crystallization process of a three-dimensional complex plasma

Science.gov (United States)

Steinmüller, Benjamin; Dietz, Christopher; Kretschmer, Michael; Thoma, Markus H.

2018-05-01

Characteristic timescales and length scales for phase transitions of real materials are in ranges where a direct visualization is unfeasible. Therefore, model systems can be useful. Here, the crystallization process of a three-dimensional complex plasma under gravity conditions is considered where the system ranges up to a large extent into the bulk plasma. Time-resolved measurements exhibit the process down to a single-particle level. Primary clusters, consisting of particles in the solid state, grow vertically and, secondarily, horizontally. The box-counting method shows a fractal dimension of df≈2.72 for the clusters. This value gives a hint that the formation process is a combination of local epitaxial and diffusion-limited growth. The particle density and the interparticle distance to the nearest neighbor remain constant within the clusters during crystallization. All results are in good agreement with former observations of a single-particle layer.

Digital silicon photomultiplier readout of a new fast and bright scintillation crystal (Ce:GFAG)

Energy Technology Data Exchange (ETDEWEB)

Lee, Yong-Seok [Department of Bio-convergence Engineering, Korea University, Seoul (Korea, Republic of); Leem, Hyun-Tae [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Yamamoto, Seiichi [Department of Medical Technology, Nagoya University Graduate School of Medicine, Nagoya (Japan); Choi, Yong, E-mail: ychoi@sogang.ac.kr [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Kamada, Kei [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); C& A corporation, Sendai (Japan); Yoshikawa, Akira [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); C& A corporation, Sendai (Japan); Institute for Material Research, Tohoku University, Sendai (Japan); Park, Sang-Geon [Department of Electrical & Electronics, Silla University, Pusan (Korea, Republic of); Yeom, Jung-Yeol, E-mail: jungyeol@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul (Korea, Republic of); School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of)

2016-10-01

A new Gadolinium Fine Aluminum Gallate (Ce:GFAG) scintillation crystal with both high energy resolution and fast timing properties has successfully been grown. Compared to Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG), this new inorganic scintillation crystal has a high luminosity similar to and a faster decay time. In this paper, we report on the timing and energy performance results of the new GFAG scintillation crystal read out with digital silicon photomultipliers (dSiPM) for positron emission tomography (PET) application. The best coincidence resolving time (FWHM) of polished 3×3×5 mm{sup 3} crystals was 223±6 ps for GFAG crystals compared to 396±28 ps for GAGG crystals and 131±3 ps for LYSO crystals respectively. An energy resolution (511 keV peak of Na-22) of 10.9±0.2% was attained with GFAG coupled to dSiPM after correcting for saturation effect, compared to 9.5±0.3% for Ce:GAGG crystals and 11.9±0.4% for LYSO crystals respectively. It is expected that this new scintillator may be competitive in terms of overall properties such as energy resolution, timing resolution and growing (raw material) cost, compared to existing scintillators for positron emission tomography (PET).

Structural and energetic effects of A2A adenosine receptor mutations on agonist and antagonist binding.

Directory of Open Access Journals (Sweden)

Henrik Keränen

Full Text Available To predict structural and energetic effects of point mutations on ligand binding is of considerable interest in biochemistry and pharmacology. This is not only useful in connection with site-directed mutagenesis experiments, but could also allow interpretation and prediction of individual responses to drug treatment. For G-protein coupled receptors systematic mutagenesis has provided the major part of functional data as structural information until recently has been very limited. For the pharmacologically important A(2A adenosine receptor, extensive site-directed mutagenesis data on agonist and antagonist binding is available and crystal structures of both types of complexes have been determined. Here, we employ a computational strategy, based on molecular dynamics free energy simulations, to rationalize and interpret available alanine-scanning experiments for both agonist and antagonist binding to this receptor. These computer simulations show excellent agreement with the experimental data and, most importantly, reveal the molecular details behind the observed effects which are often not immediately evident from the crystal structures. The work further provides a distinct validation of the computational strategy used to assess effects of point-mutations on ligand binding. It also highlights the importance of considering not only protein-ligand interactions but also those mediated by solvent water molecules, in ligand design projects.

Calculation of the energetics of chemical reactions

Energy Technology Data Exchange (ETDEWEB)

Dunning, T.H. Jr.; Harding, L.B.; Shepard, R.L.; Harrison, R.J.

1988-01-01

To calculate the energetics of chemical reactions we must solve the electronic Schroedinger equation for the molecular conformations of importance for the reactive encounter. Substantial changes occur in the electronic structure of a molecular system as the reaction progresses from reactants through the transition state to products. To describe these changes, our approach includes the following three elements: the use of multiconfiguration self-consistent field wave functions to provide a consistent zero-order description of the electronic structure of the reactants, transition state, and products; the use of configuration interaction techniques to describe electron correlation effects needed to provide quantitative predictions of the reaction energetics; and the use of large, optimized basis sets to provide the flexibility needed to describe the variations in the electronic distributions. With this approach we are able to study reactions involving as many as 5--6 atoms with errors of just a few kcal/mol in the predicted reaction energetics. Predictions to chemical accuracy, i.e., to 1 kcal/mol or less, are not yet feasible, although continuing improvements in both the theoretical methodology and computer technology suggest that this will soon be possible, at least for reactions involving small polyatomic species. 4 figs.

Picosecond excitation energy transfer of allophycocyanin studied in solution and in crystals.

Science.gov (United States)

Ranjbar Choubeh, Reza; Sonani, Ravi R; Madamwar, Datta; Struik, Paul C; Bader, Arjen N; Robert, Bruno; van Amerongen, Herbert

2018-03-01

Cyanobacteria perform photosynthesis with the use of large light-harvesting antennae called phycobilisomes (PBSs). These hemispherical PBSs contain hundreds of open-chain tetrapyrrole chromophores bound to different peptides, providing an arrangement in which excitation energy is funnelled towards the PBS core from where it can be transferred to photosystem I and/or photosystem II. In the PBS core, many allophycocyanin (APC) trimers are present, red-light-absorbing phycobiliproteins that covalently bind phycocyanobilin (PCB) chromophores. APC trimers were amongst the first light-harvesting complexes to be crystallized. APC trimers have two spectrally different PCBs per monomer, a high- and a low-energy pigment. The crystal structure of the APC trimer reveals the close distance (~21 Å) between those two chromophores (the distance within one monomer is ~51 Å) and this explains the ultrafast (~1 ps) excitation energy transfer (EET) between them. Both chromophores adopt a somewhat different structure, which is held responsible for their spectral difference. Here we used spectrally resolved picosecond fluorescence to study EET in these APC trimers both in crystallized and in solubilized form. We found that not all closely spaced pigment couples consist of a low- and a high-energy pigment. In ~10% of the cases, a couple consists of two high-energy pigments. EET to a low-energy pigment, which can spectrally be resolved, occurs on a time scale of tens of picoseconds. This transfer turns out to be three times faster in the crystal than in the solution. The spectral characteristics and the time scale of this transfer component are similar to what have been observed in the whole cells of Synechocystis sp. PCC 6803, for which it was ascribed to EET from C-phycocyanin to APC. The present results thus demonstrate that part of this transfer should probably also be ascribed to EET within APC trimers.

Energetic constraints, size gradients, and size limits in benthic marine invertebrates.

Science.gov (United States)

Sebens, Kenneth P

2002-08-01

Populations of marine benthic organisms occupy habitats with a range of physical and biological characteristics. In the intertidal zone, energetic costs increase with temperature and aerial exposure, and prey intake increases with immersion time, generating size gradients with small individuals often found at upper limits of distribution. Wave action can have similar effects, limiting feeding time or success, although certain species benefit from wave dislodgment of their prey; this also results in gradients of size and morphology. The difference between energy intake and metabolic (and/or behavioral) costs can be used to determine an energetic optimal size for individuals in such populations. Comparisons of the energetic optimal size to the maximum predicted size based on mechanical constraints, and the ensuing mortality schedule, provides a mechanism to study and explain organism size gradients in intertidal and subtidal habitats. For species where the energetic optimal size is well below the maximum size that could persist under a certain set of wave/flow conditions, it is probable that energetic constraints dominate. When the opposite is true, populations of small individuals can dominate habitats with strong dislodgment or damage probability. When the maximum size of individuals is far below either energetic optima or mechanical limits, other sources of mortality (e.g., predation) may favor energy allocation to early reproduction rather than to continued growth. Predictions based on optimal size models have been tested for a variety of intertidal and subtidal invertebrates including sea anemones, corals, and octocorals. This paper provides a review of the optimal size concept, and employs a combination of the optimal energetic size model and life history modeling approach to explore energy allocation to growth or reproduction as the optimal size is approached.

Crystallization and preliminary crystallographic analysis of human Ca2+-loaded calbindin-D28k

International Nuclear Information System (INIS)

Zhang, Chang; Sun, Yuna; Wang, Wei; Zhang, Yan; Ma, Ming; Lou, Zhiyong

2008-01-01

Human calbindin-D28k has been overexpressed in E. coli, purified and crystallized. Diffraction data were collected to 2.4 Å resolution. Calbindin-D28k is a calcium-binding protein that belongs to the troponin C superfamily. It is expressed in many tissues, including brain, intestine, kidney and pancreas, and performs roles as both a calcium buffer and a calcium sensor and carries out diverse physiological functions of importance. In order to resolve the crystal structure of human calbindin-D28k and to gain a better understanding of its biological functions, recombinant human calbindin-D28k was crystallized at 291 K using PEG 3350 as precipitant and a 2.4 Å resolution X-ray data set was collected from a single flash-cooled crystal (100 K). The crystal belonged to space group C2, with unit-cell parameters a = 108.1, b = 28.2, c = 70.6 Å, β = 107.8°. The presence of one molecule per asymmetric unit is presumed, corresponding to a Matthews coefficient of 1.75 Å 3 Da −1

Nonlinear Optical Characteristics of Crystal VioletDye Doped Polystyrene Films by Using Z-Scan Technique

Directory of Open Access Journals (Sweden)

Mahasin F. Hadi

2017-07-01

Full Text Available Z-scan technique was employed to study the nonlinear optical properties (nonlinear refractive index and nonlinear absorption coefficient for crystal violet doped polystyrene films as a function of doping ratio in chloroform solvent. Samples exhibits in closed aperture Z-scan positive nonlinear refraction (self-focusing. While in the open aperture Z-scan gives reverse saturation absorption (RSA (positive absorption for all film with different doping ratio making samples candidates for optical limiting devices for protection of sensors and eyes from energetic laser light pulses under the experimental conditions.

Reactive Energetic Plasticizers Utilizing Cu-Free Azide-Alkyne 1,3-Dipolar Cycloaddition for In-Situ Preparation of Poly(THF-co-GAP-Based Polyurethane Energetic Binders

Directory of Open Access Journals (Sweden)

Mingyang Ma

2018-05-01

Full Text Available Reactive energetic plasticizers (REPs coupled with hydroxy-telechelic poly(glycidyl azide-co-tetrahydrofuran (PGT-based energetic polyurethane (PU binders for use in solid propellants and plastic-bonded explosives (PBXs were investigated. The generation of gem-dinitro REPs along with a terminal alkyne stemmed from a series of finely designed approaches to not only satisfy common demands as conventional energetic plasticizers, but also to prevent the migration of plasticizers. The miscibility and rheological behavior of a binary mixture of PGT/REP with various REP fractions were quantitatively determined by differential scanning calorimetry (DSC and rheometer, respectively, highlighting the promising performance of REPs in the formulation process. The kinetics on the distinct reactivity of propargyl vs. 3-butynyl species of REPs towards the azide group of the PGT prepolymer in terms of Cu-free azide-alkyne 1,3-dipolar cycloaddition (1,3-DPCA was studied by monitoring 1H nuclear magnetic resonance spectroscopy and analyzing the activation energies (Ea obtained using DSC. The thermal stability of the finally cured energetic binders with the incorporation of REPs indicated that the thermal stability of the REP/PGT-based PUs was maintained independently of the REP content. The tensile strength and modulus of the PUs increased with an increase in the REP content. In addition, the energetic performance and sensitivity of REP and REP triazole species was predicted.

Thermal detection of single e-h pairs in a biased silicon crystal detector

Science.gov (United States)

Romani, R. K.; Brink, P. L.; Cabrera, B.; Cherry, M.; Howarth, T.; Kurinsky, N.; Moffatt, R. A.; Partridge, R.; Ponce, F.; Pyle, M.; Tomada, A.; Yellin, S.; Yen, J. J.; Young, B. A.

2018-01-01

We demonstrate that individual electron-hole pairs are resolved in a 1 cm2 by 4 mm thick silicon crystal (0.93 g) operated at ˜35 mK. One side of the detector is patterned with two quasiparticle-trap-assisted electro-thermal-feedback transition edge sensor arrays held near ground potential. The other side contains a bias grid with 20% coverage. Bias potentials up to ±160 V were used in the work reported here. A fiber optic provides 650 nm (1.9 eV) photons that each produce an electron-hole (e- h+) pair in the crystal near the grid. The energy of the drifting charges is measured with a phonon sensor noise σ ˜0.09 e- h+ pair. The observed charge quantization is nearly identical for h+s or e-s transported across the crystal.

International symposium 'Energetics 2004'. Symposium proceedings. Book 2

International Nuclear Information System (INIS)

2004-01-01

The holding of this Symposium was initiated by ZEMAK - Macedonian Energy Association that for the last tens of years established itself in the national and international scientific and professional circles as a competent association of professionals with the main goal to follow, promote and improve the energy sector in the country. Having in mind the fact that the power energy sector as a fundamental sector plays a main role in the development and the improvement of the rest of the industry, and in the same time has a tremendous impact on the sustainable development of the entire economy of a country, power energy sector in fact has the paramount importance in the business environment of our country. Thus, ZEMAK has historically important role as a responsible and permanent driver, promoter and initiator for resolving of all-important questions directly or indirectly interconnected with the power energy sector in the country, and therefore the entire economy in the country as well. Following the past, ZEMAK had and would always have needs of organizing national and international symposiums and workshops as a panel where directly at one place national and international power energy experts could initiate, debate and resolve all up-to-date questions in the present energy sector in Macedonia, could analyze the modern world trends in the energy sector and try to find appropriate models for their application for further development and improvement of the energy sector in our country. This international symposium has the main goal to concentrate on a single place everybody who has power energy as a permanent preoccupation and/or vocation and professional interest. To aggregate on one place various experts, from the Academy and Universities, from the business circles and companies who are preoccupied with power energy directly or indirectly in their everyday life and work. During the Symposium more than 90 scientific and/or professional papers were presented and discussed

Organization of the national energetic institutions

International Nuclear Information System (INIS)

Waltenberg, D.A.M.

1983-01-01

This text broaches, in a critical pourt of view, the organization of national energetic institutions, the need of a law revision, the problem of the rising of tariff and shows the decisions of GC01 [pt

Pulsations of Energetic Electron Pulsations In Association With Substorm Onset

Science.gov (United States)

Åsnes, A.; Stadsnes, J.; Bjordal, J.; Østgaard, N.; Haaland, S.; Rosenberg, T. J.; Detrick, D. L.

The Polar Ionospheric X-ray Imaging Experiment (PIXIE) is giving detailed images of the energetic electron precipitation when the POLAR satellite is near perigee over the Antarctica. In this area the PIXIE images have a spatial resolution of the order of 100 km, and a temporal resolution of 10 s can be obtained. In this paper we present the results of a study focusing on the onset and expansion of a substorm occuring on July 24, 1998. In this event we observe strong modulations of the energetic electron precipitation with period around 1 minute following substorm onset. The pulsations were restricted to a narrow magnetic local time sector in the pre-midnight region, about 0.5 hours wide, and showed movement towards higher latitudes and earlier lo- cal times. The event will be discussed in context of measurements from ground sta- tions and satellites in geosynchronous orbit. Precipitation of energetic electrons will be compared with VLF/ELF ground measurements. Features in the energetic elec- tron precipitation will be mapped to the magnetospheric equatorial plane by field line tracing.

Coordination chemistry and bioactivity of Ni2+, Cu2+, and Zn2+ complexes containing a bidentate NS ligand, β-N-phenyldithiocarbazic acid, and the crystal structure of β-hydroxy-β-phenylmethylene α-phenylimine

International Nuclear Information System (INIS)

Tarafder, M.T.H.; Ahmed Faizal Shamsuddin; Grouse, Karen A.; Yamin, B.M.; Ali, A.M.; Fun, H.-K.

2003-07-01

A bidentate ligand (PhDTCH) with NS donor sequence was prepared from the reaction between carbon disulfide and phenylhydrazine in ethanol. Complexes of this ligand with Ni(II), Cu(II) and Zn(II) were synthesized and characterized by elemental analyses, and various physicochemical techniques. The metal complexes were all four coordinated. In an attempt to resolve the crystal structure of PhDTCH, an ethanolic solution, after leaving for a few days gave bright crystals of PhD6, β-hydroxy-β-phenylmethylene α-phenylimine, the crystal structure of which has been resolved. The crystal packing indicated that it is monoclinic with a space group of P21/n. All of the compounds were tested against different bacteria and fungi, and also against leukemic cell lines. All of the compounds showed weak biological properties compared to standard drugs. (author)

ENERGETIC EXTREMES IN REEF FISH OCCUPYING HARSH HABITATS

DEFF Research Database (Denmark)

Steffensen, John Fleng

2009-01-01

document how relatively small changes in fin morphology has afforded some coral reef fish taxa with exceptional locomotor performance and energetic efficiency, and how this key attribute may have played a key role in the evolution and ecology of several diverse Indo-Pacific reef fish families. Using......-finned counterparts. We discuss how such differences in locomotor efficiency are pivotal to the habitat-use of these fishes, and how eco-energetic models may be used to provide new insights into spatial variations in fish demography and ecology among coral reef habitat zones....

Boron lattice location in room temperature ion implanted Si crystal

International Nuclear Information System (INIS)

Piro, A.M.; Romano, L.; Mirabella, S.; Grimaldi, M.G.

2005-01-01

The B lattice location in presence of a Si-self-interstitial (I Si ) supersaturation, controlled by energetic proton bombardment, has been studied by means of ion channelling and massive Monte Carlo simulations. B-doped layers of Si crystals with a B concentration of 1 x 10 2 B/cm 3 were grown by Molecular Beam Epitaxy. Point defect engineering techniques, with light energetic ion implants, have been applied to generate an I Si uniform injection in the electrically active layer. The displacement of B atoms out of substitutional lattice sites was induced by 650 keV proton irradiations at room temperature (R.T.) and the resultant defect configuration was investigated by ion channelling and Nuclear Reaction Analysis (NRA) techniques. Angular scans were measured both through and axes along the (1 0 0) plane using the 11 B(p,α) 8 Be nuclear reaction at 650 keV proton energy. Monte Carlo simulated angular scans were calculated considering a variety of theoretical defect configurations, supported by literature, and compared with experimental data. Our experimental scans can be fitted by a linear combination of small (0.3 A) and large B displacements (1.25 A) along the direction, compatible with the B-dumbbell oriented along as proposed by ab initio calculations

Solid-solid phase transformation via internal stress-induced virtual melting, significantly below the melting temperature. Application to HMX energetic crystal.

Science.gov (United States)

Levitas, Valery I; Henson, Bryan F; Smilowitz, Laura B; Asay, Blaine W

2006-05-25

We theoretically predict a new phenomenon, namely, that a solid-solid phase transformation (PT) with a large transformation strain can occur via internal stress-induced virtual melting along the interface at temperatures significantly (more than 100 K) below the melting temperature. We show that the energy of elastic stresses, induced by transformation strain, increases the driving force for melting and reduces the melting temperature. Immediately after melting, stresses relax and the unstable melt solidifies. Fast solidification in a thin layer leads to nanoscale cracking which does not affect the thermodynamics or kinetics of the solid-solid transformation. Thus, virtual melting represents a new mechanism of solid-solid PT, stress relaxation, and loss of coherence at a moving solid-solid interface. It also removes the athermal interface friction and deletes the thermomechanical memory of preceding cycles of the direct-reverse transformation. It is also found that nonhydrostatic compressive internal stresses promote melting in contrast to hydrostatic pressure. Sixteen theoretical predictions are in qualitative and quantitative agreement with experiments conducted on the PTs in the energetic crystal HMX. In particular, (a) the energy of internal stresses is sufficient to reduce the melting temperature from 551 to 430 K for the delta phase during the beta --> delta PT and from 520 to 400 K for the beta phase during the delta --> beta PT; (b) predicted activation energies for direct and reverse PTs coincide with corresponding melting energies of the beta and delta phases and with the experimental values; (c) the temperature dependence of the rate constant is determined by the heat of fusion, for both direct and reverse PTs; results b and c are obtained both for overall kinetics and for interface propagation; (d) considerable nanocracking, homogeneously distributed in the transformed material, accompanies the PT, as predicted by theory; (e) the nanocracking does not

Energetic ion driven Alfven eigenmodes in Large Helical Device plasmas with three-dimensional magnetic structure and their impact on energetic ion transport

International Nuclear Information System (INIS)

Toi, K; Yamamoto, S; Nakajima, N; Ohdachi, S; Sakakibara, S; Osakabe, M; Murakami, S; Watanabe, K Y; Goto, M; Kawahata, K; Kolesnichenko, Ya I; Masuzaki, S; Morita, S; Narihara, K; Narushima, Y; Takeiri, Y; Tanaka, K; Tokuzawa, T; Yamada, H; Yamada, I; Yamazaki, K

2004-01-01

In the Large Helical Device (LHD), energetic ion driven Alfven eigenmodes (AEs) and their impact on energetic ion transport have been studied. The magnetic configuration of the LHD is three-dimensional and has negative magnetic shear over a whole plasma radius in the low beta regime. These features introduce the characteristic structures of the shear Alfven spectrum. In particular, a core-localized type of toroidicity-induced AE (TAE) is most likely because the TAE gap frequency rapidly increases towards the plasma edge. Moreover, helicity-induced AEs (HAEs) can be generated through a toroidal mode coupling as well as poloidal one in the three-dimensional configuration. The following experimental results have been obtained in LHD plasmas heated by tangential neutral beam injection: (1) observation of core-localized TAEs having odd as well as even parity, (2) eigenmode transition of the core-localized TAE to global AEs (GAEs), which phenomenon is very similar to that in a reversed shear tokamak, (3) observation of HAEs of which the frequency is about eight times higher than the TAE gap frequency, (4) enhanced radial transport/loss of energetic ions caused by bursting TAEs in a relatively high beta regime, and (5) seed formation of internal transport barriers induced by TAE-induced energetic ion transport. These results will be important and interesting information for AE physics in toroidal plasmas

Energetic Electron Acceleration and Injection During Dipolarization Events in Mercury's Magnetotail

Science.gov (United States)

Dewey, Ryan M.; Slavin, James A.; Raines, Jim M.; Baker, Daniel N.; Lawrence, David J.

2017-12-01

Energetic particle bursts associated with dipolarization events within Mercury's magnetosphere were first observed by Mariner 10. The events appear analogous to particle injections accompanying dipolarization events at Earth. The Energetic Particle Spectrometer (3 s resolution) aboard MESSENGER determined the particle bursts are composed entirely of electrons with energies ≳ 300 keV. Here we use the Gamma-Ray Spectrometer high-time-resolution (10 ms) energetic electron measurements to examine the relationship between energetic electron injections and magnetic field dipolarization in Mercury's magnetotail. Between March 2013 and April 2015, we identify 2,976 electron burst events within Mercury's magnetotail, 538 of which are closely associated with dipolarization events. These dipolarizations are detected on the basis of their rapid ( 2 s) increase in the northward component of the tail magnetic field (ΔBz 30 nT), which typically persists for 10 s. Similar to those at Earth, we find that these dipolarizations appear to be low-entropy, depleted flux tubes convecting planetward following the collapse of the inner magnetotail. We find that electrons experience brief, yet intense, betatron and Fermi acceleration during these dipolarizations, reaching energies 130 keV and contributing to nightside precipitation. Thermal protons experience only modest betatron acceleration. While only 25% of energetic electron events in Mercury's magnetotail are directly associated with dipolarization, the remaining events are consistent with the Near-Mercury Neutral Line model of magnetotail injection and eastward drift about Mercury, finding that electrons may participate in Shabansky-like closed drifts about the planet. Magnetotail dipolarization may be the dominant source of energetic electron acceleration in Mercury's magnetosphere.

Magneto-Hydrodynamic Activity and Energetic Particles - Application to Beta Alfven Eigenmodes

International Nuclear Information System (INIS)

Nguyen, Ch.

2009-12-01

The goal of magnetic fusion research is to extract the power released by fusion reactions and carried by the product of these reactions, liberated at energies of the order of a few MeV. The feasibility of fusion energy production relies on our ability to confine these energetic particles, while keeping the thermonuclear plasma in safe operating conditions. For that purpose, it is necessary to understand and find ways to control the interaction between energetic particles and the thermonuclear plasma. Reaching these two goals is the general motivation for this work. More specifically, our focus is on one type of instability, the Beta Alfven Eigenmode (BAE), which can be driven by energetic particles and impact on the confinement of both energetic and thermal particles. In this work, we study the characteristics of BAEs analytically and derive its dispersion relation and structure. Next, we analyze the linear stability of the mode in the presence of energetic particles. First, a purely linear description is used, which makes possible to get an analytical linear criterion for BAE destabilization in the presence of energetic particles. This criterion is compared with experiments conducted in the Tore-Supra tokamak. Secondly, because the linear analysis reveals some features of the BAE stability which are subject to a strong nonlinear modification, the question is raised of the possibility of a sub-critical activity of the mode. We propose a simple scenario which makes possible the existence of meta-stable modes, verified analytically and numerically. Such a scenario is found to be relevant to the physics and scales characterizing BAEs. (author)

Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes

Energy Technology Data Exchange (ETDEWEB)

Gómez-Herrero, Raúl; Hidalgo, Miguel A.; Carcaboso, Fernando; Blanco, Juan J. [Dpto. de Física y Matemáticas, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid (Spain); Dresing, Nina; Klassen, Andreas; Heber, Bernd [Institut für Experimentelle und Angewandte Physik, University of Kiel, D-24118, Kiel (Germany); Temmer, Manuela; Veronig, Astrid [Institute of Physics/Kanzelhöhe Observatory, University of Graz, A-8010 Graz (Austria); Bučík, Radoslav [Institut für Astrophysik, Georg-August-Universität Göttingen, D-37077, Göttingen (Germany); Lario, David, E-mail: raul.gomezh@uah.es [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States)

2017-05-10

On 2013 December 2 and 3, the SEPT and STE instruments on board STEREO-A observed two solar energetic electron events with unusual sunward-directed fluxes. Both events occurred during a time interval showing typical signatures of interplanetary coronal mass ejections (ICMEs). The electron timing and anisotropies, combined with extreme-ultraviolet solar imaging and radio wave spectral observations, are used to confirm the solar origin and the injection times of the energetic electrons. The solar source of the ICME is investigated using remote-sensing observations and a three-dimensional reconstruction technique. In situ plasma and magnetic field data combined with energetic electron observations and a flux-rope model are used to determine the ICME magnetic topology and the interplanetary electron propagation path from the Sun to 1 au. Two consecutive flux ropes crossed the STEREO-A location and each electron event occurred inside a different flux rope. In both cases, the electrons traveled from the solar source to 1 au along the longest legs of the flux ropes still connected to the Sun. During the December 2 event, energetic electrons propagated along the magnetic field, while during the December 3 event they were propagating against the field. As found by previous studies, the energetic electron propagation times are consistent with a low number of field line rotations N < 5 of the flux rope between the Sun and 1 au. The flux rope model used in this work suggests an even lower number of rotations.

Behavior of water of crystallization in CuSO4·5H2O studied by the tritium tracer method

International Nuclear Information System (INIS)

Sato, Tetsuya; Jiao, Yurong; Imaizumi, Hiroshi; Kano, Naoki

2011-01-01

Tritium (T) is one of hydrogen isotopes, and its chemical behavior is similar to other hydrogen isotopes. Therefore tritium is used as one of tracers in chemical experimental tracer. As one of applications, we tried to apply this method to clarifying the behavior of water of crystallization in an inorganic material. The sample used was copper sulfate pentahydrate. First, this compound was tritiated, then desorbed the water of crystallization from the tritiated compound. Comparing the behavior of amount of substance with the specific activity, the following four matters have been found. (1) There is no relation between each T concentration of HTO water and the mass of the compound within the T concentration used. (2) It can be confirmed that copper sulfate pentahydrate has three kinds of energetically different water of crystallization by T tracer method. (3) Each T concentration of water of crystallization is different at the coordinate position, and the HTO molecule is hard to coordinate at the position having weak binding force. (4) The T tracer method is useful to analyze the behavior of the combined water in materials. (author)

Crystallization mechanisms of acicular crystals

Science.gov (United States)

Puel, François; Verdurand, Elodie; Taulelle, Pascal; Bebon, Christine; Colson, Didier; Klein, Jean-Paul; Veesler, Stéphane

2008-01-01

In this contribution, we present an experimental investigation of the growth of four different organic molecules produced at industrial scale with a view to understand the crystallization mechanism of acicular or needle-like crystals. For all organic crystals studied in this article, layer-by-layer growth of the lateral faces is very slow and clear, as soon as the supersaturation is high enough, there is competition between growth and surface-activated secondary nucleation. This gives rise to pseudo-twinned crystals composed of several needle individuals aligned along a crystallographic axis; this is explained by regular over- and inter-growths as in the case of twinning. And when supersaturation is even higher, nucleation is fast and random. In an industrial continuous crystallization, the rapid growth of needle-like crystals is to be avoided as it leads to fragile crystals or needles, which can be partly broken or totally detached from the parent crystals especially along structural anisotropic axis corresponding to weaker chemical bonds, thus leading to slower growing faces. When an activated mechanism is involved such as a secondary surface nucleation, it is no longer possible to obtain a steady state. Therefore, the crystal number, size and habit vary significantly with time, leading to troubles in the downstream processing operations and to modifications of the final solid-specific properties. These results provide valuable information on the unique crystallization mechanisms of acicular crystals, and show that it is important to know these threshold and critical values when running a crystallizer in order to obtain easy-to-handle crystals.

Energetics of edge oxidization of graphene nanoribbons

Science.gov (United States)

Yasuma, Airi; Yamanaka, Ayaka; Okada, Susumu

2018-06-01

On the basis of the density functional theory, we studied the geometries and energetics of O atoms adsorbed on graphene edges for simulating the initial stage of the edge oxidization of graphene. Our calculations showed that oxygen atoms are preferentially adsorbed onto the graphene edges with the zigzag portion, resulting in a large adsorption energy of about 5 eV. On the other hand, the edges with armchair shape are rarely oxidized, or the oxidization causes substantial structural reconstructions, because of the stable covalent bond at the armchair edge with the triple bond nature. Furthermore, the energetics sensitively depends on the edge angles owing to the inhomogeneity of the charge density at the edge atomic sites.

Energetic particles at venus: galileo results.

Science.gov (United States)

Williams, D J; McEntire, R W; Krimigis, S M; Roelof, E C; Jaskulek, S; Tossman, B; Wilken, B; Stüdemann, W; Armstrong, T P; Fritz, T A; Lanzerotti, L J; Roederer, J G

1991-09-27

At Venus the Energetic Particles Detector (EPD) on the Galileo spacecraft measured the differential energy spectra and angular distributions of ions >22 kiloelectron volts (keV) and electrons > 15 keV in energy. The only time particles were observed by EPD was in a series of episodic events [0546 to 0638 universal time (UT)] near closest approach (0559:03 UT). Angular distributions were highly anisotropic, ordered by the magnetic field, and showed ions arriving from the hemisphere containing Venus and its bow shock. The spectra showed a power law form with intensities observed into the 120- to 280-keV range. Comparisons with model bow shock calculations show that these energetic ions are associated with the venusian foreshock-bow shock region. Shock-drift acceleration in the venusian bow shock seems the most likely process responsible for the observed ions.

Controlling Chain Conformations of High-k Fluoropolymer Dielectrics to Enhance Charge Mobilities in Rubrene Single-Crystal Field-Effect Transistors.

Science.gov (United States)

Adhikari, Jwala M; Gadinski, Matthew R; Li, Qi; Sun, Kaige G; Reyes-Martinez, Marcos A; Iagodkine, Elissei; Briseno, Alejandro L; Jackson, Thomas N; Wang, Qing; Gomez, Enrique D

2016-12-01

A novel photopatternable high-k fluoropolymer, poly(vinylidene fluoride-bromotrifluoroethylene) P(VDF-BTFE), with a dielectric constant (k) between 8 and 11 is demonstrated in thin-film transistors. Crosslinking P(VDF-BTFE) reduces energetic disorder at the dielectric-semiconductor interface by controlling the chain conformations of P(VDF-BTFE), thereby leading to approximately a threefold enhancement in the charge mobility of rubrene single-crystal field-effect transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CIRCUMSOLAR ENERGETIC PARTICLE DISTRIBUTION ON 2011 NOVEMBER 3

Energy Technology Data Exchange (ETDEWEB)

Gómez-Herrero, R.; Blanco, J.J.; Rodríguez-Pacheco, J. [SRG, Universidad de Alcalá, E-28871 Alcalá de Henares (Spain); Dresing, N.; Klassen, A.; Heber, B.; Banjac, S. [IEAP, Christian-Albrechts-Universität zu Kiel, D-24118 Kiel (Germany); Lario, D. [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States); Agueda, N. [Departament d' Astronomia i Meteorologia. Institut de Ciències del Cosmos. Universitat de Barcelona, E-08028 Barcelona (Spain); Malandraki, O. E., E-mail: raul.gomezh@uah.es [IAASARS, National Observatory of Athens, GR-15236 Penteli (Greece)

2015-01-20

Late on 2011 November 3, STEREO-A, STEREO-B, MESSENGER, and near-Earth spacecraft observed an energetic particle flux enhancement. Based on the analysis of in situ plasma and particle observations, their correlation with remote sensing observations, and an interplanetary transport model, we conclude that the particle increases observed at multiple locations had a common single-source active region and the energetic particles filled a very broad region around the Sun. The active region was located at the solar backside (as seen from Earth) and was the source of a large flare, a fast and wide coronal mass ejection, and an EIT wave, accompanied by type II and type III radio emission. In contrast to previous solar energetic particle events showing broad longitudinal spread, this event showed clear particle anisotropies at three widely separated observation points at 1 AU, suggesting direct particle injection close to the magnetic footpoint of each spacecraft, lasting for several hours. We discuss these observations and the possible scenarios explaining the extremely broad particle spread for this event.

Deep energetic trap states in organic photovoltaic devices

KAUST Repository

Shuttle, Christopher G.; Treat, Neil D.; Douglas, Jessica D.; Frechet, Jean; Chabinyc, Michael L.

2011-01-01

The nature of energetic disorder in organic semiconductors is poorly understood. In photovoltaics, energetic disorder leads to reductions in the open circuit voltage and contributes to other loss processes. In this work, three independent optoelectronic methods were used to determine the long-lived carrier populations in a high efficiency N-alkylthieno[3,4-c]pyrrole-4,6-dione (TPD) based polymer: fullerene solar cell. In the TPD co-polymer, all methods indicate the presence of a long-lived carrier population of ∼ 10 15 cm -3 on timescales ≤100 μs. Additionally, the behavior of these photovoltaic devices under optical bias is consistent with deep energetic lying trap states. Comparative measurements were also performed on high efficiency poly-3-hexylthiophene (P3HT): fullerene solar cells; however a similar long-lived carrier population was not observed. This observation is consistent with a higher acceptor concentration (doping) in P3HT than in the TPD-based copolymer. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deep energetic trap states in organic photovoltaic devices

KAUST Repository

Shuttle, Christopher G.

2011-11-23

The nature of energetic disorder in organic semiconductors is poorly understood. In photovoltaics, energetic disorder leads to reductions in the open circuit voltage and contributes to other loss processes. In this work, three independent optoelectronic methods were used to determine the long-lived carrier populations in a high efficiency N-alkylthieno[3,4-c]pyrrole-4,6-dione (TPD) based polymer: fullerene solar cell. In the TPD co-polymer, all methods indicate the presence of a long-lived carrier population of ∼ 10 15 cm -3 on timescales ≤100 μs. Additionally, the behavior of these photovoltaic devices under optical bias is consistent with deep energetic lying trap states. Comparative measurements were also performed on high efficiency poly-3-hexylthiophene (P3HT): fullerene solar cells; however a similar long-lived carrier population was not observed. This observation is consistent with a higher acceptor concentration (doping) in P3HT than in the TPD-based copolymer. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigations of the energy and angular dependence of ultra-short radiation lengths in Si, Ge and W single crystals

CERN Multimedia

Very recently, experiments NA33 and WA81 have shown that pair production by energetic photons incident along crystalline directions is strongly enhanced as compared to the Bethe-Heitler value for amorphous targets. The enhanced pair production sets in at around 40 GeV in Ge crystals and rises almost linearly with photon energy up to a calculated maximum enhancement of around thirty. In Si, this maximum is expected to be nearly two orders of magnitude above the Bethe-Heitler value.\\\\ For GeV electrons/positrons incident along crystal axes, the radiation energy loss also shows a very large enhancement of approximately two orders of magnitude. In a 0.4 mm W crystal, a 100 GeV electron is expected to emit on average 70% of its total energy.\\\\ The combination of these two dramatic enhancements means that the electromagnetic shower develops much faster around crystalline directions, corresponding to ultrashort radiation lengths.\\\\ The aim of this experiment is to investigate the shower development in ...

Extreme UV and X-ray scattering measurements from a rough LiF crystal surface characterized by electron micrography

DEFF Research Database (Denmark)

Alehyane; Arbaoui; Barchewitz

1989-01-01

XUV and X-ray scattering by a LiF crystal is measured. The angular distribution of the scattered radiation (ADSR) reveals characteristic features, side peaks or asymmetry. The surface of the sample is statistically characterized by a microdensitometer analysis of electron micrographs resolving th...

Temperature-induced band shift in bulk γ-InSe by angle-resolved photoemission spectroscopy

Science.gov (United States)

Xu, Huanfeng; Wang, Wei; Zhao, Yafei; Zhang, Xiaoqian; Feng, Yue; Tu, Jian; Gu, Chenyi; Sun, Yizhe; Liu, Chang; Nie, Yuefeng; Edmond Turcu, Ion C.; Xu, Yongbing; He, Liang

2018-05-01

Indium selenide (InSe) has recently become popular research topics because of its unique layered crystal structure, direct band gap and high electron mobilities. In this work, we have acquired the electronic structure of bulk γ-InSe at various temperatures using angle-resolved photoemission spectroscopy (ARPES). We have also found that as the temperature decreases, the valence bands of γ-InSe exhibit a monotonic shift to lower binding energies. This band shift is attributed to the change of lattice parameters and has been validated by variable temperature X-ray diffraction measurements and theoretical calculations.

Time-resolved x-ray diffraction analysis of the experimental dehydration of serpentine at high pressure

International Nuclear Information System (INIS)

Inoue, Toru; Yoshimi, Isamu; Yamada, Akihiro; Kikegawa, Takumi

2009-01-01

Time-resolved, in situ X-ray diffraction analysis was used to determine the dehydration rate and kinetics of serpentine during experimental dehydration at high pressures. The capsule used comprises a diamond sleeve fitted with Au or Pt lids in order to provide high-quality, time-resolved X-ray diffraction data. Antigorite quickly dehydrated to enstatite + forsterite + fluid within 2 h at 650degC below ∼6 GPa. Avrami modeling of the results and SEM observations of the partially dehydrated sample revealed that the nucleation rate was quite high for enstatite but low for forsterite, showing incubation periods of ∼10 min before appearing. The crystallization of these minerals is controlled largely by the composition of the fluid generated from serpentine dehydration. The dehydration boundary determined below 6 GPa in the present study is consistent with the results of previous phase equilibrium studies. This study indicates that serpentine in a subducting slab dehydrates rapidly below 6 GPa when the slab intersects the dehydration boundary conditions. (author)

Energetic stress: The reciprocal relationship between energy availability and the stress response.

Science.gov (United States)

Harrell, C S; Gillespie, C F; Neigh, G N

2016-11-01

The worldwide epidemic of metabolic syndromes and the recognized burden of mental health disorders have driven increased research into the relationship between the two. A maladaptive stress response is implicated in both mental health disorders and metabolic disorders, implicating the hypothalamic-pituitary-adrenal (HPA) axis as a key mediator of this relationship. This review explores how an altered energetic state, such as hyper- or hypoglycemia, as may be manifested in obesity or diabetes, affects the stress response and the HPA axis in particular. We propose that changes in energetic state or energetic demands can result in "energetic stress" that can, if prolonged, lead to a dysfunctional stress response. In this review, we summarize the role of the hypothalamus in modulating energy homeostasis and then briefly discuss the relationship between metabolism and stress-induced activation of the HPA axis. Next, we examine seven mechanisms whereby energetic stress interacts with neuroendocrine stress response systems, including by glucocorticoid signaling both within and beyond the HPA axis; by nutrient-induced changes in glucocorticoid signaling; by impacting the sympathetic nervous system; through changes in other neuroendocrine factors; by inducing inflammatory changes; and by altering the gut-brain axis. Recognizing these effects of energetic stress can drive novel therapies and prevention strategies for mental health disorders, including dietary intervention, probiotics, and even fecal transplant. Copyright © 2015 Elsevier Inc. All rights reserved.

Of the crystal chemistry of Ruddlesden-Porter type structures in high Tc ceramic superconductors

International Nuclear Information System (INIS)

Dwivedi, A.; Cormack, A.N.

1990-01-01

This paper reports on atomistic computer simulation employed to examine the energetics and crystal chemistry of some Ruddlesden-Popper type oxide superconductors. Similar structural patterns have been noticed in the superconducting oxides. The formation of Ruddlesden-Popper type layers (alternating slabs of rocksalt and perovskite structures) is similar in many respects to that seen in the system Sr-Ti-O. However, there are some significant differences, for example, the rocksalt and perovskite blocks in the new superconducting compounds are not necessarily electrically neutral unlike in the Sr-Ti-O system and this may well lead to significant differences in their structural chemistry

Energetic aspects of diclofenac acid in crystal modifications and in solutions--mechanism of solvation, partitioning and distribution.

Science.gov (United States)

Perlovich, German L; Surov, Artem O; Hansen, Lars Kr; Bauer-Brandl, Annette

2007-05-01

Temperature dependency of saturated vapor pressure and heat capacity for the diclofenac acid (Form II) were measured and thermodynamic functions of sublimation calculated (DeltaG(sub)(298) = 49.3 kJ x mol(-1); DeltaH(sub)(298) = 115.6 +/- 1.3 kJ x mol(-1); DeltaS(sub)(298) = 222 +/- 4 J x mol(-1) x K(-1)). Crystal polymorphic Forms I (P2(1)/c) and II (C2/c) of diclofenac acid have been prepared and characterized by X-ray diffraction experiments. The difference between crystal lattice energies of the two forms were obtained by solution calorimetry: DeltaDeltaH(sol)(I --> II) = 1.6 +/- 0.4 kJ x mol(-1). Temperature dependencies of the solubility in buffers with pH 2.0 and 7.4, n-octanol and n-hexane were measured. The thermodynamic functions of solubility, solvation, and transfer processes were deduced. Specific and non-specific solvation terms were distinguished using the transfer from the "inert" n-hexane to the other solvents. The transfer of diclofenac acid molecules from the buffers to n-octanol (partitioning and distribution) is an entropy driven process. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Crystallization and preliminary crystallographic analysis of human Ca{sup 2+}-loaded calbindin-D28k

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chang [Tsinghua-Nankai-IBP Joint Research Group for Structural Biology, Tsinghua University, Beijing 100084 (China); Sun, Yuna [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing 100101 (China); Wang, Wei; Zhang, Yan [Tsinghua-Nankai-IBP Joint Research Group for Structural Biology, Tsinghua University, Beijing 100084 (China); Ma, Ming [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing 100101 (China); Lou, Zhiyong, E-mail: louzy@xtal.tsinghua.edu.cn [Tsinghua-Nankai-IBP Joint Research Group for Structural Biology, Tsinghua University, Beijing 100084 (China)

2008-02-01

Human calbindin-D28k has been overexpressed in E. coli, purified and crystallized. Diffraction data were collected to 2.4 Å resolution. Calbindin-D28k is a calcium-binding protein that belongs to the troponin C superfamily. It is expressed in many tissues, including brain, intestine, kidney and pancreas, and performs roles as both a calcium buffer and a calcium sensor and carries out diverse physiological functions of importance. In order to resolve the crystal structure of human calbindin-D28k and to gain a better understanding of its biological functions, recombinant human calbindin-D28k was crystallized at 291 K using PEG 3350 as precipitant and a 2.4 Å resolution X-ray data set was collected from a single flash-cooled crystal (100 K). The crystal belonged to space group C2, with unit-cell parameters a = 108.1, b = 28.2, c = 70.6 Å, β = 107.8°. The presence of one molecule per asymmetric unit is presumed, corresponding to a Matthews coefficient of 1.75 Å{sup 3} Da{sup −1}.

An automatic system to study sperm motility and energetics

OpenAIRE

Shi, LZ; Nascimento, JM; Chandsawangbhuwana, C; Botvinick, EL; Berns, MW

2008-01-01

An integrated robotic laser and microscope system has been developed to automatically analyze individual sperm motility and energetics. The custom-designed optical system directs near-infrared laser light into an inverted microscope to create a single-point 3-D gradient laser trap at the focal spot of the microscope objective. A two-level computer structure is described that quantifies the sperm motility (in terms of swimming speed and swimming force) and energetics (measuring mid-piece membr...

The source of multi spectral energy of solar energetic electron

Energy Technology Data Exchange (ETDEWEB)

Herdiwijaya, Dhani [Astronomy Division and Bosscha Observatory, Faculty Mathematics and Natural Sciences, Intitute Technology of Bandung, Ganesha 10, Bandung, Indonesia 40132 dhani@as.itb.ac.id (Indonesia)

2015-04-16

We study the solar energetic electron distribution obtained from ACE and GOES satellites which have different altitudes and electron spectral energy during the year 1997 to 2011. The electron spectral energies were 0.038–0.315 MeV from EPAM instrument onboard ACE satellite and >2 MeV from GOES satellite. We found that the low electron energy has no correlation with high energy. In spite of we have corrected to the altitude differences. It implied that they originated from time dependent events with different sources and physical processes at the solar atmosphere. The sources of multi spectral energetic electron were related to flare and CME phenomena. However, we also found that high energetic electron comes from coronal hole.

Capturing the most energetic cosmic rays

International Nuclear Information System (INIS)

Mantsch, P.

1999-01-01

The methods of energy measurement applied to the most energetic cosmic rays are described. The rays are so rare that two gigantic systems of detectors are proposed to detect at least some of them (the Pierre Auger Project ). (Z.J.)

High frequency fishbone driven by passing energetic ions in tokamak plasmas

Science.gov (United States)

Wang, Feng; Yu, L. M.; Fu, G. Y.; Shen, Wei

2017-05-01

High frequency fishbone instability driven by passing energetic ions was first reported in the Princeton beta experiment with tangential neutral-beam-injection (Heidbrink et al 1986 Phys. Rev. Lett. 57 835-8). It could play an important role for ITER-like burning plasmas, where α particles are mostly passing particles. In this work, a generalized energetic ion distribution function and finite drift orbit width effect are considered to improve the theoretical model for passing particle driving fishbone instability. For purely passing energetic ions with zero drift orbit width, the kinetic energy δ {{W}k} is derived analytically. The derived analytic expression is more accurate as compared to the result of previous work (Wang 2001 Phys. Rev. Lett. 86 5286-8). For a generalized energetic ion distribution function, the fishbone dispersion relation is derived and is solved numerically. Numerical results show that broad and off-axis beam density profiles can significantly increase the beam ion beta threshold {βc} for instability and decrease mode frequency.

Energetic costs of performance in trained and untrained Anolis carolinensis lizards.

Science.gov (United States)

Lailvaux, Simon P; Wang, Andrew Z; Husak, Jerry F

2018-03-12

The energetic costs of performance constitute a non-trivial component of animals' daily energetic budgets. However, we currently lack an understanding of how those costs are partitioned among the various stages of performance development, maintenance, and production. We manipulated individual investment in performance by training Anolis carolinensis lizards for endurance or sprinting ability. We then measured energetic expenditure both at rest and immediately following exercise to test whether such training alters the maintenance and production costs of performance. Trained lizards had lower resting metabolic rates than controls, suggestive of a maintenance saving associated with enhanced performance as opposed to a cost. Production costs also differed, with sprint-trained lizards incurring the largest energetic performance cost and experiencing the longest recovery times compared to endurance trained and control animals. Although performance training modifies metabolism, production costs are probably the key drivers of trade-offs between performance and other life-history traits in this species. © 2018. Published by The Company of Biologists Ltd.

Energetic proton generation in ultra-intense laser-solid interactions

International Nuclear Information System (INIS)

Wilks, S.C.; Langdon, A.B.; Cowan, T.E.; Roth, M.; Singh, M.; Hatchett, S.; Key, M. H.; Pennington, D.; MacKinnon, A.; Snavely, R.A.

2001-01-01

An explanation for the energetic ions observed in the PetaWatt experiments is presented. In solid target experiments with focused intensities exceeding 10 20 W/cm 2 , high-energy electron generation, hard bremsstrahlung, and energetic protons have been observed on the backside of the target. In this report, an attempt is made to explain the physical process present that will explain the presence of these energetic protons, as well as explain the number, energy, and angular spread of the protons observed in experiment. In particular, we hypothesize that hot electrons produced on the front of the target are sent through to the back off the target, where they ionize the hydrogen layer there. These ions are then accelerated by the hot electron cloud, to tens of MeV energies in distances of order tens of μm, whereupon they end up being detected in the radiographic and spectrographic detectors

Chemical rocket propulsion a comprehensive survey of energetic materials

CERN Document Server

Shimada, Toru; Sinditskii, Valery; Calabro, Max

2017-01-01

Developed and expanded from the work presented at the New Energetic Materials and Propulsion Techniques for Space Exploration workshop in June 2014, this book contains new scientific results, up-to-date reviews, and inspiring perspectives in a number of areas related to the energetic aspects of chemical rocket propulsion. This collection covers the entire life of energetic materials from their conceptual formulation to practical manufacturing; it includes coverage of theoretical and experimental ballistics, performance properties, as well as laboratory-scale and full system-scale, handling, hazards, environment, ageing, and disposal. Chemical Rocket Propulsion is a unique work, where a selection of accomplished experts from the pioneering era of space propulsion and current technologists from the most advanced international laboratories discuss the future of chemical rocket propulsion for access to, and exploration of, space. It will be of interest to both postgraduate and final-year undergraduate students in...

Field-controllable Spin-Hall Effect of Light in Optical Crystals: A Conoscopic Mueller Matrix Analysis.

Science.gov (United States)

Samlan, C T; Viswanathan, Nirmal K

2018-01-31

Electric-field applied perpendicular to the direction of propagation of paraxial beam through an optical crystal dynamically modifies the spin-orbit interaction (SOI), leading to the demonstration of controllable spin-Hall effect of light (SHEL). The electro- and piezo-optic effects of the crystal modifies the radially symmetric spatial variation in the fast-axis orientation of the crystal, resulting in a complex pattern with different topologies due to the symmetry-breaking effect of the applied field. This introduces spatially-varying Pancharatnam-Berry type geometric phase on to the paraxial beam of light, leading to the observation of SHEL in addition to the spin-to-vortex conversion. A wave-vector resolved conoscopic Mueller matrix measurement and analysis provides a first glimpse of the SHEL in the biaxial crystal, identified via the appearance of weak circular birefringence. The emergence of field-controllable fast-axis orientation of the crystal and the resulting SHEL provides a new degree of freedom for affecting and controlling the spin and orbital angular momentum of photons to unravel the rich underlying physics of optical crystals and aid in the development of active photonic spin-Hall devices.

Rural energetic development: cuban experience; El desarrollo energetico rural: experiencia cubana

Energy Technology Data Exchange (ETDEWEB)

Aguilera Barciela, M [Secretariado Ejecutivo, Comision Nacional de Energia, La Habana(Cuba)

1994-07-01

The development of electro energetic national system in Cuba has been directed to the following objectives: to brake the rural population's exodus toward the cities, electrification of dairy farm, interconnection to the system electro energetic of all the sugar central production, these improves the rural population's conditions life.

Energy transport by energetic electrons released during solar flares. I - Thermal versus nonthermal processes

Science.gov (United States)

Winglee, R. M.; Dulk, G. A.; Pritchett, P. L.

1988-01-01

The propagation of energetic electrons through a flaring flux tube is studied in an attempt to determine how the energy of the electrons is deposited in the flux tube. One-dimensional electrostatic particle simulations are used in the present investigation. As the energetic electrons propagate into the system, a return current of ambient plasma electrons and some of the energetic electrons is drawn into the energetic electron source. It is found that, as the ambient temperature relative to the ion temperature increases above about 3, the heated return-current electrons can excite ion-sound waves.

Introduction to global energetic problems

International Nuclear Information System (INIS)

Gicquel, R.

1992-01-01

This book gives a view on global energetic problems and proposes a thorough economic analysis on principle aspects taken into account: energy supply, depending energy sources and available technologic channels, relationships between macro-economy and energy demand, new size of energy problems (environmental effects, overcosts of renewable energy sources, necessity of an high technologic development...). 38 refs

About the wind energetics development

International Nuclear Information System (INIS)

Strebkov, D.S.; Kharitonov, V.P.; Murugov, V.P.; Sokol'skij, A.K.

1996-01-01

The review of wind power energetics state in USA, Europe, Russia is given. The data of EC on wind power plants production in different periods are presented. The directions of scientific-research works with the purpose of increasing the level of wind power industry of Russia corresponding to economics demands were elaborated. (author). 8 refs., 3 tabs

A comparison of energetic ions in the plasma depletion layer and the quasi-parallel magnetosheath

Science.gov (United States)

Fuselier, Stephen A.

1994-01-01

Energetic ion spectra measured by the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE) downstream from the Earth's quasi-parallel bow shock (in the quasi-parallel magnetosheath) and in the plasma depletion layer are compared. In the latter region, energetic ions are from a single source, leakage of magnetospheric ions across the magnetopause and into the plasma depletion layer. In the former region, both the magnetospheric source and shock acceleration of the thermal solar wind population at the quasi-parallel shock can contribute to the energetic ion spectra. The relative strengths of these two energetic ion sources are determined through the comparison of spectra from the two regions. It is found that magnetospheric leakage can provide an upper limit of 35% of the total energetic H(+) population in the quasi-parallel magnetosheath near the magnetopause in the energy range from approximately 10 to approximately 80 keV/e and substantially less than this limit for the energetic He(2+) population. The rest of the energetic H(+) population and nearly all of the energetic He(2+) population are accelerated out of the thermal solar wind population through shock acceleration processes. By comparing the energetic and thermal He(2+) and H(+) populations in the quasi-parallel magnetosheath, it is found that the quasi-parallel bow shock is 2 to 3 times more efficient at accelerating He(2+) than H(+). This result is consistent with previous estimates from shock acceleration theory and simulati ons.

Simulation study of energetic ion transport due to Alfven eigenmodes in LHD plasma

International Nuclear Information System (INIS)

Todo, Yasushi; Nakajima, Noriyoshi; Osakabe, Masaki; Yamamoto, Satoshi; Spong, Donald A.

2008-01-01

The creation of holes and clumps in an energetic ion energy spectrum associated with Alfven eigenmodes was examined using the neutral particle analyzer (NPA) on the LHD shot no.47645. The difference in slowing-down times between the holes and clumps suggested that the energetic ions were transported over 10% of the plasma minor radius. The spatial profile and frequency of the Alfven eigenmodes were analyzed with the AE3D code. The phase space structures of the energetic ions on the NPA line-of-sight were investigated with Poincare plots, where an oscillating Alfven eigenmode was employed for earth plot. The phase space regions trapped by the Alfven eigenmodes appeared as islands in the Poincare plots. The radial width of the islands corresponded to the transport distance of the energetic ions. Since island width depends on Alfven eigenmode amplitude, it was found that Alfven eigenmodes with amplitude δB r /B - 10 -3 transported energetic ions over 10% of the minor radius. (author)

High resolution monochromatic X-ray imaging system based on spherically bent crystals

International Nuclear Information System (INIS)

Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C. M.; Seely, J.; Feldman, U.; Holland, G.

1997-01-01

We have developed a new X-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. The imaging system is used for plasma diagnostics of the main target and for characterization of potential backlighters. A spherically curved quartz crystal (2d=6.687 A, R=200 mm) is used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the X-ray optical system is 3-4 μm. Time resolved backlit monochromatic images of CH planar targets driven by the Nike facility have been obtained with 6-7 μm spatial resolution

Strong non-radial propagation of energetic electrons in solar corona

Science.gov (United States)

Klassen, A.; Dresing, N.; Gómez-Herrero, R.; Heber, B.; Veronig, A.

2018-06-01

Analyzing the sequence of solar energetic electron events measured at both STEREO-A (STA) and STEREO-B (STB) spacecraft during 17-21 July 2014, when their orbital separation was 34°, we found evidence of a strong non-radial electron propagation in the solar corona below the solar wind source surface. The impulsive electron events were associated with recurrent flare and jet (hereafter flare/jet) activity at the border of an isolated coronal hole situated close to the solar equator. We have focused our study on the solar energetic particle (SEP) event on 17 July 2014, during which both spacecraft detected a similar impulsive and anisotropic energetic electron event suggesting optimal connection of both spacecraft to the parent particle source, despite the large angular separation between the parent flare and the nominal magnetic footpoints on the source surface of STA and STB of 68° and 90°, respectively. Combining the remote-sensing extreme ultraviolet (EUV) observations, in-situ plasma, magnetic field, and energetic particle data we investigated and discuss here the origin and the propagation trajectory of energetic electrons in the solar corona. We find that the energetic electrons in the energy range of 55-195 keV together with the associated EUV jet were injected from the flare site toward the spacecraft's magnetic footpoints and propagate along a strongly non-radial and inclined magnetic field below the source surface. From stereoscopic (EUV) observations we estimated the inclination angle of the jet trajectory and the respective magnetic field of 63° ± 11° relative to the radial direction. We show how the flare accelerated electrons reach very distant longitudes in the heliosphere, when the spacecraft are nominally not connected to the particle source. This example illustrates how ballistic backmapping can occasionally fail to characterize the magnetic connectivity during SEP events. This finding also provides an additional mechanism (one among others

'In situ' straining in the HVEM of neutron irradiated copper crystals

International Nuclear Information System (INIS)

Johnson, E.; Hirsch, P.B.

1976-01-01

High energy neutron irradiated copper single crystals strained 'in situ' in the high voltage electron microscope are observed to yield in relatively few strongly developed slip bands. The deformation in the slip bands is caused by glide of inclined dislocations close to screw orientation belonging to the primary slip system. Radiation induced point defect clusters are swept up by the dislocations whereby superjogs are formed. Some of the jogs will be sessile and act as pinning points for the gliding dislocations, which bow out under the applied stress to form perfect dipoles mainly of edge nature, as well as faulted dipoles, which are finally pinched off. The effective stress measured from the radius of curvature of the bowed-out dislocations is in agreement with resolved flow stress measurements from irradiated bulk crystals. (Auth.)

Energetic Cost of Ichthyophonus Infection in Juvenile Pacific Herring (Clupea pallasii

Directory of Open Access Journals (Sweden)

Johanna J. Vollenweider

2011-01-01

Full Text Available The energetic costs of fasting and Ichthyophonus infection were measured in juvenile Pacific herring (Clupea pallasii in a lab setting at three temperatures. Infected herring incurred significant energetic costs, the magnitude of which depended on fish condition at the time of infection (fat versus lean. Herring that were fed continually and were in relatively good condition at the time of infection (fat never stored lipid despite ad libitum feeding. In feeding herring, the energetic cost of infection was a 30% reduction in total energy content relative to controls 52 days post infection. Following food deprivation (lean condition, infection caused an initial delay in the compensatory response of herring. Thirty-one days after re-feeding, the energetic cost of infection in previously-fasted fish was a 32% reduction in total energy content relative to controls. Body composition of infected herring subsequently recovered to some degree, though infected herring never attained the same energy content as their continuously fed counterparts. Fifty-two days after re-feeding, the energetic cost of infection in previously-fasted fish was a 6% reduction in total energy content relative to controls. The greatest impacts of infection occurred in colder temperatures, suggesting Ichthyophonus-induced reductions in body condition may have greater consequences in the northern extent of herring's range, where juveniles use most of their energy reserves to survive their first winter.

Energetic Cost of Ichthyophonus Infection in Juvenile Pacific Herring (Clupea pallasii).

Science.gov (United States)

Vollenweider, Johanna J; Gregg, Jake L; Heintz, Ron A; Hershberger, Paul K

2011-01-01

The energetic costs of fasting and Ichthyophonus infection were measured in juvenile Pacific herring (Clupea pallasii) in a lab setting at three temperatures. Infected herring incurred significant energetic costs, the magnitude of which depended on fish condition at the time of infection (fat versus lean). Herring that were fed continually and were in relatively good condition at the time of infection (fat) never stored lipid despite ad libitum feeding. In feeding herring, the energetic cost of infection was a 30% reduction in total energy content relative to controls 52 days post infection. Following food deprivation (lean condition), infection caused an initial delay in the compensatory response of herring. Thirty-one days after re-feeding, the energetic cost of infection in previously-fasted fish was a 32% reduction in total energy content relative to controls. Body composition of infected herring subsequently recovered to some degree, though infected herring never attained the same energy content as their continuously fed counterparts. Fifty-two days after re-feeding, the energetic cost of infection in previously-fasted fish was a 6% reduction in total energy content relative to controls. The greatest impacts of infection occurred in colder temperatures, suggesting Ichthyophonus-induced reductions in body condition may have greater consequences in the northern extent of herring's range, where juveniles use most of their energy reserves to survive their first winter.

Energetic aspects of skeletal muscle contraction: implications of fiber types.

Science.gov (United States)

Rall, J A

1985-01-01

In this chapter fundamental energetic properties of skeletal muscles as elucidated from isolated muscle preparations are described. Implications of these intrinsic properties for the energetic characterization of different fiber types and for the understanding of locomotion have been considered. Emphasis was placed on the myriad of physical and chemical techniques that can be employed to understand muscle energetics and on the interrelationship of results from different techniques. The anaerobic initial processes which liberate energy during contraction and relaxation are discussed in detail. The high-energy phosphate (approximately P) utilized during contraction and relaxation can be distributed between actomyosin ATPase or cross-bridge cycling (70%) and the Ca2+ ATPase of the sacroplasmic reticulum (30%). Muscle shortening increases the rate of approximately P hydrolysis, and stretching a muscle during contraction suppresses the rate of approximately P hydrolysis. The economy of an isometric contraction is defined as the ratio of isometric mechanical response to energetic cost and is shown to be a fundamental intrinsic parameter describing muscle energetics. Economy of contraction varies across the animal kingdom by over three orders of magnitude and is different in different mammalian fiber types. In mammalian skeletal muscles differences in economy of contraction can be attributed mainly to differences in the specific actomyosin and Ca2+ ATPase of muscles. Furthermore, there is an inverse relationship between economy of contraction and maximum velocity of muscle shortening (Vmax) and maximum power output. This is a fundamental relationship. Muscles cannot be economical at developing and maintaining force and also exhibit rapid shortening. Interestingly, there appears to be a subtle system of unknown nature that modulates the Vmax and economy of contraction. Efficiency of a work-producing contraction is defined and contrasted to the economy of contraction

Los Alamos energetic particle sensor systems at geostationary orbit

International Nuclear Information System (INIS)

Baker, D.N.; Aiello, W.; Asbridge, J.R.; Belian, R.D.; Higbie, P.R.; Klebesadel, R.W.; Laros, J.G.; Tech, E.R.

1985-01-01

The Los Alamos National Laboratory has provided energetic particle sensors for a variety of spacecraft at the geostationary orbit (36,000 km altitude). The sensor system called the Charged Particle Analyzer (CPA) consists of four separate subsystems. The LoE and HiE subsystems measure electrons in the energy ranges 30 to 300 keV and 200 to 2000 keV, respectively. The LoP and HiP subsystems measure ions in the ranges 100 to 600 keV and 0.40 to 150 MeV, respectively. A separate sensor system called the spectrometer for energetic electrons (SEE) measures very high-energy electrons (2 to 15 MeV) using advanced scintillator design. In this paper we describe the relationship of operational anomalies and spacecraft upsets to the directly measured energetic particle environments at 6.6 R/sub E/. We also compare and contrast the CPA and SEE instrument design characteristics with the next generation of Los Alamos instruments to be flown at geostationary altitudes

Observation of energetic particle mode by using microwave reflectometer

International Nuclear Information System (INIS)

Tokuzawa, T.; Kawahata, K.; Sakakibara, S.; Toi, K.; Osakabe, M.; Yamamoto, S.

2006-01-01

Two heterodyne reflectometer systems are utilized for the fluctuation measurement in the Large Helical Device (LHD). By using the extraordinary polarized wave, we can measure the corresponding value to the combined fluctuation with the electron density and the magnetic field in the plasma core region even if the radial electron density profile is flat. E-band system has three channels of fixed frequencies of 78, 72, 65 GHz. The system is very convenient to observe magnetohydrodynamics (MHD) phenomena such as energetic particle driven Alfven eigenmodes, even if the system works as an interferometer mode. The detailed behaviour of the energetic particle mode is studied when low-n MHD burst is occurred. It seems to be caused that the spatial distribution of high energy particle is changed by such a MHD-burst. Also to know the radial distribution of MHD mode, frequency swept R-band reflectometer is applied for the first time. It seems to be successfully detected the energetic particle mode and toroidal Alfven eigenmode. (author)

Time-resolved two million year old supernova activity discovered in the earth's microfossil record

Energy Technology Data Exchange (ETDEWEB)

Bishop, Shawn; Ludwig, Peter; Chernenko, Valentina; Deveva, Boyana; Faestermann, Thomas; Famulok, Nicolai; Fimiani, Leticia; Gomez, Jose; Hain, Karin; Korschinek, Gunther [Physik Department, Technische Universitaet Muenchen, Garching (Germany); Egli, Ramon [Geomagnetism and Gravimetry, Central Institute for Metrology and Geodynamics, Vienna (Austria); Hanzlik, Marianne [Chemie Department, FG Elektronmikroskopie, Technische Universitaet Muenchen, Garching (Germany); Merchel, Silke; Rugel, Georg [Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Dresden (Germany)

2016-07-01

Using accelerator mass spectrometry, we have conducted a search for live, supernova-produced, {sup 60}Fe atoms within biogenically produced magnetite (Fe{sub 3}O{sub 4}) crystals contained in two Pacific Ocean sediment cores. We have found a time-resolved {sup 60}Fe signal in both sediment cores, above background, centered at approximately 2.1 Myr ago and spanning approximately 800 kyr duration (full width half maximum). The onset of this signal coincides with a known marine extinction event at the Pleiocene/Pleistocene boundary, and its shape will require eventual astrophysical interpretation to understand.

Assessment of In Situ Time Resolved Shock Experiments at Synchrotron Light Sources*

Science.gov (United States)

Belak, J.; Ilavsky, J.; Hessler, J. P.

2005-07-01

Prior to fielding in situ time resolved experiments of shock wave loading at the Advanced Photon Source, we have performed feasibility experiments assessing a single photon bunch. Using single and poly-crystal Al, Ti, V and Cu shock to incipient spallation on the gas gun, samples were prepared from slices normal to the spall plane of thickness 100-500 microns. In addition, single crystal Al of thickness 500 microns was shocked to incipient spallation and soft recovered using the LLNL e-gun mini-flyer system. The e-gun mini-flyer impacts the sample target producing a 10's ns flat-top shock transient. Here, we present results for imaging, small-angle scattering (SAS), and diffraction. In particular, there is little SAS away from the spall plane and significant SAS at the spall plane, demonstrating the presence of sub-micron voids. * Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38 and work performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Energetic materials standards – Chemical compatibility

NARCIS (Netherlands)

Tuukkanen, I.M.; Bouma, R.H.B.

2014-01-01

Subgroup A Energetic Materials Team, SG/A (EMT), develops and maintains standards that are relevant to all life-cycle phases of ammunition/weapon systems. STANAG 4147 is the standard regarding chemical compatibility of explosives with munition components, and is a document of prime importance.

An energetically consistent vertical mixing parameterization in CCSM4

DEFF Research Database (Denmark)

Nielsen, Søren Borg; Jochum, Markus; Eden, Carsten

2018-01-01

An energetically consistent stratification-dependent vertical mixing parameterization is implemented in the Community Climate System Model 4 and forced with energy conversion from the barotropic tides to internal waves. The structures of the resulting dissipation and diffusivity fields are compared......, however, depends greatly on the details of the vertical mixing parameterizations, where the new energetically consistent parameterization results in low thermocline diffusivities and a sharper and shallower thermocline. It is also investigated if the ocean state is more sensitive to a change in forcing...

Collective Thomson scattering in tokamaks having energetic ions

International Nuclear Information System (INIS)

Myer, R.C.; Woskov, P.P.; Machuzak, J.S.; Sigmar, D.J.; Cohn, D.R.; Bretz, N.L.; Efthimion, P.C.; Colestock, P.L.

1989-01-01

The authors discuss how collective Thomson scattering (CTS), using high power gyrotrons or long wavelength lasers,m shows promise as a powerful non-intrusive diagnostic of fast-ion transport as it may be capable of measuring the fast-ion velocity distribution and density profile with good spatial and temporal resolution. In addition, CTS may be used as a diagnostic for detecting localized power deposition in the background plasma. High power CTS systems are presently being planned for TFTR, JET, and CIT. Recent theoretical analysis suggests that an energetic (200-800 keV) He 3 minority can be produced in TFTR by ion cyclotron heating (ICH). Such an energetic population would be useful for simulating the energetic alpha-particles produced in a burning plasma. Since the ICH generated distribution is non-Maxwellian, the authors generalize the theoretical analysis of CTS to allow for particle distributions which can be represented by various orthogonal polynomial expansions. They evaluate the efficacy of CTS in detecting a fast He 3 component and determine the sensitivity of the diagnostic to the details of the ion distribution. In particular, the effectiveness of a planned 56 GHz gyrotron CTS diagnostic for TFTR is evaluated

Evaluating the Bulk Lorentz Factors of Outflow Material: Lessons Learned from the Extremely Energetic Outburst GRB 160625B

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuan-Zhu; Wang, Hao; Zhang, Shuai; Liang, Yun-Feng; Jin, Zhi-Ping; He, Hao-Ning; Liao, Neng-Hui; Fan, Yi-Zhong; Wei, Da-Ming, E-mail: liangyf@pmo.ac.cn, E-mail: jin@pmo.ac.cn, E-mail: dmwei@pmo.ac.cn [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Science, Nanjing, 210008 (China)

2017-02-10

GRB 160625B is an extremely bright outburst with well-monitored afterglow emission. The geometry-corrected energy is high, up to ∼5.2 × 10{sup 52} erg or even ∼8 × 10{sup 52} erg, rendering it the most energetic GRB prompt emission recorded so far. We analyzed the time-resolved spectra of the prompt emission and found that in some intervals there were likely thermal-radiation components and the high energy emission was characterized by significant cutoff. The bulk Lorentz factors of the outflow material are estimated accordingly. We found out that the Lorentz factors derived in the thermal-radiation model are consistent with the luminosity-Lorentz factor correlation found in other bursts, as well as in GRB 090902B for the time-resolved thermal-radiation components, while the spectral cutoff model yields much lower Lorentz factors that are in tension with the constraints set by the electron pair Compton scattering process. We then suggest that these spectral cutoffs are more likely related to the particle acceleration process and that one should be careful in estimating the Lorentz factors if the spectrum cuts at a rather low energy (e.g., ∼tens of MeV). The nature of the central engine has also been discussed, and a stellar-mass black hole is favored.

Spontaneous emission of quantum dots in disordered photonic crystal waveguides

DEFF Research Database (Denmark)

Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren

2010-01-01

We report on the enhancement of the spontaneous emission rate of single semiconductor quantum dots embedded in a photonic crystal waveguide with engineered disorder. Random high-Q cavities, that are signature of Anderson localization, are measured in photoluminescence experiments and appear...... in the slow light regime of the waveguide mode. Time resolved experiments show a 15-fold enhancement of the spontaneous emission rate, with coupling efficiencies of single photons into Anderson localized cavity modes of 94%. These results show that the performances of Anderson-localized cavities...

Analysis of phase transitions and crystal structures of novel benzothiophene derivatives

Science.gov (United States)

Zhang, Shuo

Although single crystal X-ray diffraction remains the most important technique for analyzing periodically ordered structures at atomic resolution, single crystal X-ray diffraction of organic macromolecules is challenged by difficulty in growing single crystals of desired size and quality. Electron crystallography of organic macromolecules, on the other hand, is limited by image resolution due to radiation damage and highly dependent on high-resolution instrumentation. Novel alkylated benzothiophene derivatives synthesized previously can be readily fabricated into semiconductor devices for various applications (photodetectors, explosive sensors, field-effect transistors, light-emitting diodes, etc.) via solution process. The object of this research is to identify phase transitions of organic macromolecules of this kind via differential scanning calorimetry and temperature-resolved wide angle X-ray diffraction, and to determine their lattice parameters and space groups by reconstruction of their reciprocal space via transmission electron microscopy/selected area electron diffraction followed by refinement with X-ray diffraction, supplemented by polarized light microscopy. Computer simulation was performed to rationalize the molecular packing schemes, so as to understand the origin of their electronic performance from crystallographic perspective.

Elements of the new energetic policy in Macedonia

International Nuclear Information System (INIS)

Tomovski, Aleksandar

1995-01-01

In the field of the energetic policy and development in both energy production and energy consumption in Macedonia, one can fill an uncertainty and development concept absence. It is clear that this is a result of the stress that Macedonian economy suffers from after the disintegration of the former Yugoslavia as a market and economic unit, as well as of the establishment of different economic and market norms. It is obvious that in the energetics, as one of the basic economic sectors,the situation has to be stabilized very soon as well as in advance analysed right decisions have to be made. (author). 1 ill

Synthesis and characterization of an energetic compound Cu(Mtta)2(NO3)2 and effect on thermal decomposition of ammonium perchlorate

International Nuclear Information System (INIS)

Yang, Qi; Chen, Sanping; Xie, Gang; Gao, Shengli

2011-01-01

Highlights: ► A new energetic compound Cu(Mtta) 2 (NO 3 ) 2 has been synthesized and structural characterized. ► Sensitivity tests reveal that the compound is insensitive to mechanical stimuli. ► Cu(Mtta) 2 (NO 3 ) 2 accelerates the decomposition of Ammonium perchlorate (AP), which is the key component of composite solid propellant. - Abstract: An energetic coordination compound Cu(Mtta) 2 (NO 3 ) 2 has been synthesized by using 1-methyltetrazole (Mtta) as ligand and its structure has been characterized by X-ray single crystal diffraction. The central copper (II) cation was coordinated by four O atoms from two Mtta ligands and two N atoms from two NO 3 − anions to form a six-coordinated and distorted octahedral structure. 2D superamolecular layer structure was formed by the extensive intermolecular hydrogen bonds between Mtta ligands and NO 3 − anions. Thermal decomposition process of the compound was predicted based on DSC and TG-DTG analyses results. The kinetic parameters of the first exothermic process of the compound were studied by the Kissinger's and Ozawa–Doyle's methods. Sensitivity tests revealed that the compound was insensitive to mechanical stimuli. In addition, compound was explored as additive to promote the thermal decomposition of ammonium perchlorate (AP) by differential scanning calorimetry.

Very High Performance High Nitrogen Energetic Ingredients and Energetic Polymers for Structural Components

Science.gov (United States)

2011-12-31

13. SUPPLEMENTARY NOTES SoUoWtoo^ 14. ABSTRACT This project investigated new energetic materials for use with a triazole cured binder system ...The reaction was repeated using two equivalents of KH. An even more insoluble product was obtained. Figure 8 and 9 show the C-13 and N-15 CP/MAS...Sonnenberg, M. Hada, M. Ehara, K. Toyota , R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda , O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr

Physics with energetic radioactive ion beams

International Nuclear Information System (INIS)

Henning, W.F.

1996-01-01

Beams of short-lived, unstable nuclei have opened new dimensions in studies of nuclear structure and reactions. Such beams also provide key information on reactions that take place in our sun and other stars. Status and prospects of the physics with energetic radioactive beams are summarized

Energetic Particle Estimates for Stellar Flares

Science.gov (United States)

Youngblood, Allison; Chamberlin, Phil; Woods, Tom

2018-01-01

In the heliosphere, energetic particles are accelerated away from the Sun during solar flares and/or coronal mass ejections where they frequently impact the Earth and other solar system bodies. Solar (or stellar) energetic particles (SEPs) not only affect technological assets, but also influence mass loss and chemistry in planetary atmospheres (e.g., depletion of ozone). SEPs are increasingly recognized as an important factor in assessing exoplanet habitability, but we do not yet have constraints on SEP emission from any stars other than the Sun. Until indirect measurements are available, we must assume solar-like particle production and apply correlations between solar flares and SEPs detected near Earth to stellar flares. We present improved scaling relations between solar far-UV flare flux and >10 MeV proton flux near Earth. We apply these solar scaling relations to far-UV flares from exoplanet host stars and discuss the implications for modeling chemistry and mass loss in exoplanet atmospheres.

Nematic liquid crystals on sinusoidal channels: the zigzag instability.

Science.gov (United States)

Silvestre, Nuno M; Romero-Enrique, Jose M; Telo da Gama, Margarida M

2017-01-11

Substrates which are chemically or topographically patterned induce a variety of liquid crystal textures. The response of the liquid crystal to competing surface orientations, typical of patterned substrates, is determined by the anisotropy of the elastic constants and the interplay of the relevant lengths scales, such as the correlation length and the surface geometrical parameters. Transitions between different textures, usually with different symmetries, may occur under a wide range of conditions. We use the Landau-de Gennes free energy to investigate the texture of nematics in sinusoidal channels with parallel anchoring bounded by nematic-air interfaces that favour perpendicular (hometropic) anchoring. In micron size channels 5CB was observed to exhibit a non-trivial texture characterized by a disclination line, within the channel, which is broken into a zigzag pattern. Our calculations reveal that when the elastic anisotropy of the nematic does not favour twist distortions the defect is a straight disclination line that runs along the channel, which breaks into a zigzag pattern with a characteristic period, when the twist elastic constant becomes sufficiently small when compared to the splay and bend constants. The transition occurs through a twist instability that drives the defect line to rotate from its original position. The interplay between the energetically favourable twist distortions that induce the defect rotation and the liquid crystal anchoring at the surfaces leads to the zigzag pattern. We investigate in detail the dependence of the periodicity of the zigzag pattern on the geometrical parameters of the sinusoidal channels, which in line with the experimental results is found to be non-linear.

Combined effects of space charge and energetic disorder on photocurrent efficiency loss of field-dependent organic photovoltaic devices

International Nuclear Information System (INIS)

Yoon, Sangcheol; Hwang, Inchan; Park, Byoungchoo

2015-01-01

The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole–Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers. (paper)

Energetics of Elementary Steps in Catalysis and Their Use to Search for New Catalysts

Science.gov (United States)

Wolcott, Christopher A.

We live in a society based upon the mass production of chemicals. Whether it is the fuel in a car, the fertilizers used to make food, or the plastics present in just about everything, these chemicals are so ubiquitous that it is difficult to imagine living in a world without them. Nearly all consumer chemicals are produced through a catalytic process, the vast majority of which are heterogeneous. On top of their current, massive presence, heterogeneous catalysts are also expected to play an important role in new emerging technologies such as fuel cells, hydrogen production, green chemistry, and more. Considering their ubiquity in the present and their potential uses in the future, it is no surprise that improving catalyst performance is a very active area of research. Yet despite their ubiquity, and despite their long history of active study, there remains much which is unknown about the fundamentals of catalysts on surfaces. One of the major gaps is in quantitative understanding of the energetics of elementary steps in catalytic reactions on surfaces. The stability or instability of molecules and molecular fragments adsorbed on surfaces in these elementary steps is KEY to understanding what makes one material an effective catalyst and another less effective. In general, one must use single-crystal model catalysts to produce well-defined adsorbates. Classic studies of the energetics of adsorbates on such surfaces have typically involved techniques (such as temperature programmed desorption or equilibrium adsorption experiments) which limit the types of systems which can be studied to those where adsorption is reversible. For most catalytic intermediates present in these elementary steps, this is not the case. Upon adsorption and heating many molecules fall apart and produce strongly bound adsorbates which further dissociate at higher temperatures, or will not leave the surface until they have reacted with something else. Single crystal adsorption calorimetry (SCAC

Local protoplanetary disk ionisation by T Tauri star energetic particles

Science.gov (United States)

Fraschetti, F.; Drake, J.; Cohen, O.; Garraffo, C.

2017-10-01

The evolution of protoplanetary disks is believed to be driven largely by viscosity. The ionization of the disk that gives rise to viscosity is caused by X-rays from the central star or by energetic particles released by shock waves travelling into the circumstellar medium. We have performed test-particle numerical simulations of GeV-scale protons traversing a realistic magnetised wind of a young solar mass star with a superposed small-scale turbulence. The large-scale field is generated via an MHD model of a T Tauri wind, whereas the isotropic (Kolmogorov power spectrum) turbulent component is synthesised along the particles' trajectories. We have combined Chandra observations of T Tauri flares with solar flare scaling for describing the energetic particle spectrum. In contrast with previous models, we find that the disk ionization is dominated by X-rays except within narrow regions where the energetic particles are channelled onto the disk by the strongly tangled and turbulent field lines; the radial thickness of such regions broadens with the distance from the central star (5 stellar radii or more). In those regions, the disk ionization due to energetic particles can locally dominate the stellar X-rays, arguably, out to large distances (10, 100 AU) from the star.

Assessment of CRBR core disruptive accident energetics

International Nuclear Information System (INIS)

Theofanous, T.G.; Bell, C.R.

1984-03-01

The results of an independent assessment of core disruptive accident energetics for the Clinch River Breeder Reactor are presented in this document. This assessment was performed for the Nuclear Regulatory Commission under the direction of the CRBR Program Office within the Office of Nuclear Reactor Regulation. It considered in detail the accident behavior for three accident initiators that are representative of three different classes of events; unprotected loss of flow, unprotected reactivity insertion, and protected loss of heat sink. The primary system's energetics accommodation capability was realistically, yet conservatively, determined in terms of core events. This accommodation capability was found to be equivalent to an isentropic work potential for expansion to one atmosphere of 2550 MJ or a ramp rate of about 200 $/s applied to a classical two-phase disassembly

Structural and biophysical characterization of an epitope-specific engineered Fab fragment and complexation with membrane proteins: implications for co-crystallization.

Science.gov (United States)

Johnson, Jennifer L; Entzminger, Kevin C; Hyun, Jeongmin; Kalyoncu, Sibel; Heaner, David P; Morales, Ivan A; Sheppard, Aly; Gumbart, James C; Maynard, Jennifer A; Lieberman, Raquel L

2015-04-01

Crystallization chaperones are attracting increasing interest as a route to crystal growth and structure elucidation of difficult targets such as membrane proteins. While strategies to date have typically employed protein-specific chaperones, a peptide-specific chaperone to crystallize multiple cognate peptide epitope-containing client proteins is envisioned. This would eliminate the target-specific chaperone-production step and streamline the co-crystallization process. Previously, protein engineering and directed evolution were used to generate a single-chain variable (scFv) antibody fragment with affinity for the peptide sequence EYMPME (scFv/EE). This report details the conversion of scFv/EE to an anti-EE Fab format (Fab/EE) followed by its biophysical characterization. The addition of constant chains increased the overall stability and had a negligible impact on the antigen affinity. The 2.0 Å resolution crystal structure of Fab/EE reveals contacts with larger surface areas than those of scFv/EE. Surface plasmon resonance, an enzyme-linked immunosorbent assay, and size-exclusion chromatography were used to assess Fab/EE binding to EE-tagged soluble and membrane test proteins: namely, the β-barrel outer membrane protein intimin and α-helical A2a G protein-coupled receptor (A2aR). Molecular-dynamics simulation of the intimin constructs with and without Fab/EE provides insight into the energetic complexities of the co-crystallization approach.

MOISTURE HUMIDITY EQUILIBRIUM OF WOOD CHIPS FROM ENERGETIC CROPS

Directory of Open Access Journals (Sweden)

Jan Barwicki

2008-09-01

Full Text Available Processes occurring during storage of wood chips for energetic or furniture industry purposes were presented. As a result of carried out investigations, dependences of temperature and relative humidity changes of surrounding air were shown. Modified Henderson equation can be utilized for computer simulation of storing and drying processes concerning wood chips for energetic and furniture industry purposes. It reflects also obtained results from experiments carried out with above mentioned material. Using computer simulation program we can examine different wood chips storing conditions to avoid overheating and loss problems.

Global Positioning System (GPS) Energetic Particle Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Energetic particle data from the CXD and BDD instrument on the GPS constellation are available to the space weather research community. The release of these data...

Wrong directions of the energetic policy; Descaminhos da politica energetica

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Joaquim Francisco

1997-12-31

The energetic planning should take an important role in the formulation of the economic and social development policy of any country. This work presents the opinion of the author in relation to this issue in what concerns the Brazilian experience. Several actions considered wrong by the author, which were taken by the government in what concerns energetic policy are presented and their expected consequences in the near future are discussed 6 refs., 1 tab.

Strength and deformation of shocked diamond single crystals: Orientation dependence

Science.gov (United States)

Lang, J. M.; Winey, J. M.; Gupta, Y. M.

2018-03-01

Understanding and quantifying the strength or elastic limit of diamond single crystals is of considerable scientific and technological importance, and has been a subject of long standing theoretical and experimental interest. To examine the effect of crystalline anisotropy on strength and deformation of shocked diamond single crystals, plate impact experiments were conducted to measure wave profiles at various elastic impact stresses up to ˜120 GPa along [110] and [111] crystal orientations. Using laser interferometry, particle velocity histories and shock velocities in the diamond samples were measured and were compared with similar measurements published previously for shock compression along the [100] direction. Wave profiles for all three orientations showed large elastic wave amplitudes followed by time-dependent inelastic deformation. From the measured wave profiles, the elastic limits were determined under well characterized uniaxial strain loading conditions. The measured elastic wave amplitudes for the [110] and [111] orientations were lower for higher elastic impact stress (stress attained for an elastic diamond response), consistent with the result reported previously for [100] diamond. The maximum resolved shear stress (MRSS) on the {111}⟨110⟩ slip systems was determined for each orientation, revealing significant orientation dependence. The MRSS values for the [100] and [110] orientations (˜33 GPa) are 25%-30% of theoretical estimates; the MRSS value for the [111] orientation is significantly lower (˜23 GPa). Our results demonstrate that the MRSS depends strongly on the stress component normal to the {111} planes or the resolved normal stress (RNS), suggesting that the RNS plays a key role in inhibiting the onset of inelastic deformation. Lower elastic wave amplitudes at higher peak stress and the effect of the RNS are inconsistent with typical dislocation slip mechanisms of inelastic deformation, suggesting instead an inelastic response

The energetics of electric organ discharge generation in gymnotiform weakly electric fish.

Science.gov (United States)

Salazar, Vielka L; Krahe, Rüdiger; Lewis, John E

2013-07-01

Gymnotiform weakly electric fish produce an electric signal to sense their environment and communicate with conspecifics. Although the generation of such relatively large electric signals over an entire lifetime is expected to be energetically costly, supporting evidence to date is equivocal. In this article, we first provide a theoretical analysis of the energy budget underlying signal production. Our analysis suggests that wave-type and pulse-type species invest a similar fraction of metabolic resources into electric signal generation, supporting previous evidence of a trade-off between signal amplitude and frequency. We then consider a comparative and evolutionary framework in which to interpret and guide future studies. We suggest that species differences in signal generation and plasticity, when considered in an energetics context, will not only help to evaluate the role of energetic constraints in the evolution of signal diversity but also lead to important general insights into the energetics of bioelectric signal generation.

Study on Energetic Ions Behavior in Plasma Facing Materials at Lower Temperature

International Nuclear Information System (INIS)

Morimoto, Y.; Sugiyama, T.; Akahori, S.; Kodama, H.; Tega, E.; Sasaki, M.; Oyaidu, M.; Kimura, H.; Okuno, K.

2003-01-01

An apparatus equipped with X-ray Photoelectron Spectroscopy (XPS) and Thermal Desorption Spectroscopy (TDS) was constructed to study interactions of energetic hydrogen isotopes with plasma facing materials. It is a remarkable feature of the apparatus that energetic ion implantation is carried out at around 150K to study reactions of energetic ions with matrix by suppressing the reactions of thermalized ions. Using this apparatus, TDS experiments for pyrolytic graphite implanted with energetic D 2 ions at 173 and 373K were carried out. The experimental results suggest that the deuterium implanted was released through a four-step release processes, involving three D 2 and one CD x (x = 2, 3 and 4) desorption processes. Two deuterium and CD x desorption processes were observed in the temperature range from 700 to 1200 K. In addition, a new deuterium desorption process was observed for the deuterium-implanted sample at 173 K. This has never been observed for deuterium-implanted graphite implanted at temperatures higher than room temperature

Band gap control in a line-defect magnonic crystal waveguide

Energy Technology Data Exchange (ETDEWEB)

Morozova, M. A., E-mail: mamorozovama@yandex.ru; Grishin, S. V.; Sadovnikov, A. V.; Romanenko, D. V.; Sharaevskii, Yu. P.; Nikitov, S. A. [Laboratory ' Metamaterials,' Saratov State University, Astrakhanskaya 83, Saratov 410012 (Russian Federation)

2015-12-14

We report on the experimental observation of the spin wave spectrum control in a line-defect magnonic crystal (MC) waveguide. We demonstrate the possibility to control the forbidden frequency band (band gap) for spin waves tuning the line-defect width. In particular, this frequency may be greater or lower than the one of 1D MC waveguide without line-defect. By means of space-resolved Brillouin light scattering technique, we study the localization of magnetization amplitude in the line-defect area. We show that the length of this localization region depends on the line-defect width. These results agree well with theoretical calculations of spin wave spectrum using the proposed model of two coupled magnonic crystal waveguides. The proposed simple geometry of MC with line-defect can be used as a logic and multiplexing block for application in the novel field of magnonic devices.

Influence of temperature upon dislocation mobility and elastic limit of single crystal HgI2

International Nuclear Information System (INIS)

Milstein, F.; Farber, B.; Kim, K.; van den Berg, L.; Schnepple, W.

1982-01-01

The practical importance of studying mechanical properties and dislocation structure of HgI 2 is reviewed briefly. Specifically, the performance of single crystal HgI 2 radiation detectors is evidently sensitive to crystalline imperfections; the dislocation structure, in turn, can be altered during detector fabrication, depending upon the mechanical properties of the crystal and the stresses to which the crystal is subjected. The influence of temperature upon dislocation mobility and plasticity in vapor-grown crystals of mercuric iodide is examined. Dislocation mobiity is determined by measuring the lengths of the longest arms of dislocation etch pit rosettes on (001) surfaces following microhardness indentation and chemical etch. Measurements were made in the range from room temperature to the phase transition temperature of 127 0 C. Dislocation mobility was found to be an increasing function of temperature, with the effect accelerating as the phase transition is approached. Increasing temperature was also found to lower the critical resolved shear stress for plastic deformation on slip on (001) planes. In these contexts, the vapor-grown crystals are clearly softer at their elevated growth temperatures. The results are discussed in terms of a dislocation model involving soft and hard glide dislocations

Amorphous-tetrahedral diamondlike carbon layered structures resulting from film growth energetics

Science.gov (United States)

Siegal, M. P.; Barbour, J. C.; Provencio, P. N.; Tallant, D. R.; Friedmann, T. A.

1998-08-01

High-resolution transmission electron microscopy (HRTEM) shows that amorphous-tetrahedral diamondlike carbon (a-tC) films grown by pulsed-laser deposition on Si(100) consist of three-to-four layers, depending on the growth energetics. We estimate the density of each layer using both HRTEM image contrast and Rutherford backscattering spectrometry. The first carbon layer and final surface layer have relatively low density. The bulk of the film between these two layers has higher density. For films grown under the most energetic conditions, there exists a superdense a-tC layer between the interface and bulk layers. The density of all four layers, and the thickness of the surface and interfacial layers, correlate well with the energetics of the depositing carbon species.

Bio-energetic rehabilitation of human health with use of therapeutic fasting

International Nuclear Information System (INIS)

Kechutkina, E.M.; Inyushin, V.M.; Asanov, D.R.

2000-01-01

The work devoted to study of mothers' and children's coming from ecologically unfavorable regions rehabilitation measures effectiveness and health improvement in condition of sanatorium-resort conditions. Comprehensive approach was developed in this direction. The approach includes of bio-energetic, psychologic, clearing measures in combination with weight-out faltering and observation of health status with help of electro-physiological methods. In result of conducted study and following analysis positive influence of hunger (in complex with resonance photoactivation bio-energetic excesses, psycho-training) process of bio-energetic rehabilitation of human health. It is concluded that most powerful energizing of reserve opportunities of body takes place at complete refusal from food and transition on internal nourishment (endogenous) that was confirm at 7-day festering by indexes of homeostasis shift

Mathematical theories of classical particle channeling in perfect crystals

International Nuclear Information System (INIS)

Dumas, H. Scott

2005-01-01

We present an overview of our work on rigorous mathematical theories of channeling for highly energetic positive particles moving in classical perfect crystal potentials. Developed over the last two decades, these theories include: (i) a comprehensive, highly mathematical theory based on Nekhoroshev's theorem which embraces both axial and planar channeling as well as certain non-channeling particle motions (ii) a theory of axial channeling for relativistic particles based on a single-phase averaging method for ordinary differential equations and (iii) a theory of planar channeling for relativistic particles based on a two-phase averaging method for ordinary differential equations. Here we touch briefly on (i) and (ii), then focus on (iii). Together these theories place Lindhard's continuum model approximations on a firm mathematical foundation, and should serve as the starting point for more refined mathematical treatments of channeling

Optimization of a large-area detector-block based on SiPM and pixelated LYSO crystal arrays.

Science.gov (United States)

Calva-Coraza, E; Alva-Sánchez, H; Murrieta-Rodríguez, T; Martínez-Dávalos, A; Rodríguez-Villafuerte, M

2017-10-01

We present the performance evaluation of a large-area detector module based on the ArrayC-60035-64P, an 8×8 array of tileable, 7.2mm pitch, silicon photomultipliers (SiPM) by SensL, covering a total area of 57.4mm×57.4mm. We characterized the ArrayC-60035-64P, operating at room temperature, using LYSO pixelated crystal arrays of different pitch sizes (1.075, 1.430, 1.683, 2.080 and 2.280mm) to determine the resolvable crystal size. After an optimization process, a 7mm thick coupling light guide was used for all crystal pitches. To identify the interaction position a 16-channel (8 columns, 8 rows) symmetric charge division (SCD) readout board together with a center-of-gravity algorithm was used. Based on this, we assembled the detector modules using a 40×40 LYSO, 1.43mm pitch array, covering the total detector area. Calibration was performed using a 137 Cs source resulting in excellent crystal maps with minor geometric distortion, a mean 4.1 peak-to-valley ratio and 9.6% mean energy resolution for 662keV photons in the central region. The resolvability index was calculated in the x and y directions with values under 0.42 in all cases. We show that these large area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, without processing a big number of signals, attaining excellent energy resolution and detector uniformity. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Spectrally and Spatially Resolved Smith-Purcell Radiation in Plasmonic Crystals with Short-Range Disorder

Directory of Open Access Journals (Sweden)

I. Kaminer

2017-01-01

Full Text Available Electrons interacting with plasmonic structures can give rise to resonant excitations in localized plasmonic cavities and to collective excitations in periodic structures. We investigate the presence of resonant features and disorder in the conventional Smith-Purcell effect (electrons interacting with periodic structures and observe the simultaneous excitation of both the plasmonic resonances and the collective excitations. For this purpose, we introduce a new scanning-electron-microscope-based setup that allows us to probe and directly image new features of electron-photon interactions in nanophotonic structures like plasmonic crystals with strong disorder. Our work creates new possibilities for probing nanostructures with free electrons, with potential applications that include tunable sources of short-wavelength radiation and plasmonic-based particle accelerators.

High resolution monochromatic X-ray imaging system based on spherically bent crystals

International Nuclear Information System (INIS)

Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C.M.; Seely, J.; Feldman, U.; Holland, G.

1997-01-01

We have developed a new X-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser [1,2]. The imaging system is used for plasma diagnostics of the main target and for characterization of potential backlighters. A spherically curved quartz crystal (2d=6.687 Angstrom, R=200mm) is used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the X-ray optical system is 3 endash 4 μm. Time resolved backlit monochromatic images of CH planar targets driven by the Nike facility have been obtained with 6 endash 7 μm spatial resolution. copyright 1997 American Institute of Physics

Rapid decompression and desorption induced energetic failure in coal

Directory of Open Access Journals (Sweden)

Shugang Wang

2015-06-01

Full Text Available In this study, laboratory experiments are conducted to investigate the rapid decompression and desorption induced energetic failure in coal using a shock tube apparatus. Coal specimens are recovered from Colorado at a depth of 610 m. The coal specimens are saturated with the strong sorbing gas CO2 for a certain period and then the rupture disc is suddenly broken on top of the shock tube to generate a shock wave propagating upwards and a rarefaction wave propagating downwards through the specimen. This rapid decompression and desorption has the potential to cause energetic fragmentation in coal. Three types of behaviors in coal after rapid decompression are found, i.e. degassing without fragmentation, horizontal fragmentation, and vertical fragmentation. We speculate that the characteristics of fracture network (e.g. aperture, spacing, orientation and stiffness and gas desorption play a role in this dynamic event as coal can be considered as a dual porosity, dual permeability, dual stiffness sorbing medium. This study has important implications in understanding energetic failure process in underground coal mines such as coal gas outbursts.

Thickness determination of thin solid films by angle-resolved X-ray fluorescence spectrometry using monochromatized synchrotron radiation

Science.gov (United States)

Schmitt, W.; Drotbohm, P.; Rothe, J.; Hormes, J.; Ottermann, C. R.; Bange, K.

1995-05-01

Thickness measurements by the method of angle-resolved, self-ratio X-ray fluorescence spectrometry (AR/SR/XFS) have been carried out on thin solid films using monochromatized synchrotron radiation at the Bonn storage ring ELSA. Synchrotron radiation was monochromatized by means of a double-crystal monochromator and fluorescence radiation was detected by a Si(Li) semiconductor detector. The results for sample systems consisting of Au on Si, Cr on SiO2 and TiO2 on alkali-free glass are very satisfactory and agree well with results obtained by other methods.

Self-Detection of Leaking Pipes by One-Dimensional Photonic Crystals

International Nuclear Information System (INIS)

Zhou Yan; Yin Li-Qun

2012-01-01

We report a new self-detection control system for leaking pipes by making use of the surface defects of 1D photonic crystals, where the key concept is analog to the Bragg fiber structure. The current low costs and coating techniques of SiO 2 are beneficial to the applications, and its error is below the standard requirement. The problem of leaking pipes can be resolved by devising a remote pipeline control system which combines a long-distance pipeline and a signal transmission system. (fundamental areas of phenomenology(including applications))

Retrofit of a high power Nd:glass laser system with liquid crystal polarizers

International Nuclear Information System (INIS)

Jacobs, S.D.; Cerqua, K.A.; Kessler, T.J.; Seka, W.; Bahr, R.

1985-03-01

The glass development laser (GDL), has been operating at the Laboratory for Laser Energetics since 1978. This Nd:phosphate glass system produces high peak power optical radiation at lambda = 1054 nm or lambda = 351 nm for use in studying the interaction physics of intense laser beams with matter. The amplifier staging incorporates the propagation of linearly and circularly polarized light in rod amplifiers which vary in diameter from 16 mm to 90 mm. Numerous quartz or mica quarter waveplates and Brewster angle dielectric thin film polarizers are required to limit accumulated phase retardation between amplification stages and to accommodate interstage Pockels' cell isolation switches. We have recently replaced most of the waveplate-dielectric polarizer combinations in GDL with liquid crystal polarizers. Comprised of 11 μm thick cholesteric fluids sandwiched between optical quality glass plates, liquid crystal polarizers provide excellent polarization properties, low insertion loss, angular insensitivity, and laser damage resistance at lambda = 1054 nm. The design, fabrication, and performance of left-handed and right-handed circular polarizers will be discussed

Energetics and efficiency of a molecular motor model

International Nuclear Information System (INIS)

Fogedby, Hans C; Svane, Axel

2013-01-01

The energetics and efficiency of a linear molecular motor model proposed by Mogilner et al are analyzed from an analytical point of view. The model, which is based on protein friction with a track, is described by coupled Langevin equations for the motion in combination with coupled master equations for the ATP hydrolysis. Here the energetics and efficiency of the motor are addressed using a many body scheme with focus on the efficiency at maximum power (EMP). It is found that the EMP is reduced from about 10% in a heuristic description of the motor to about 1 per mille when incorporating the full motor dynamics, owing to the strong dissipation associated with the motor action. (paper)

Resolving the age of Wilson Creek Formation tephras and the Mono Lake excursion using high-resolution SIMS dating of allanite and zircon rims

Science.gov (United States)

Vazquez, J. A.; Lidzbarski, M. I.

2012-12-01

Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and interbedded rhyolitic tephras yield discordant 14C and 40Ar/39Ar results due to open-system effects, carbon reservoir uncertainties, as well as abundant xenocrysts entrained during eruption. Ion microprobe (SIMS) 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yields ages that effectively date eruption of key tephra beds and resolve age uncertainties about the Wilson Creek stratigraphy. To date the final several micrometers of crystal growth, individual allanite and zircon crystals were embedded in soft indium to allow sampling of unpolished rims. Isochron ages derived from rims on coexisting allanite and zircon (± glass) from hand-selected pumiceous pyroclasts delimit the timing of Wilson Creek sedimentation between Ashes 7 and 19 (numbering of Lajoie, 1968) to the interval between ca. 27 to ca. 62 ka. The interiors of individual allanite and zircon crystals sectioned in standard SIMS mounts yield model 238U-230Th ages that are mostly hydrologic responses in the Sierra Nevada and Mono Basin to climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation. Moreover, the results demonstrate that high-spatial resolution SIMS dating of accessory mineral rims is an alternative and promising approach for resolving the depositional ages of silicic tephras containing minerals that crystallized over protracted intervals or that are plagued by incorporation of xenocrysts

Nuclear energetics as environmentally affable source - present and and future

International Nuclear Information System (INIS)

Suchomel, J.

2002-01-01

In this paper the situation in nuclear energetics in the world in 2000 year is presented. Climatic changes initiated by burning of the fossil fuels an influence of nuclear energetics are discussed. Author informs that European Union and U.S.A. supports developing of nuclear energetics. Nuclear phobia from radiation risk of some inhabitants is compared with risks of other man activities. Possibilities of the electricity production by alternative sources are compared. Liability of the Slovak Republic for decommissioning of two reactor of the V-1 Jaslovske Bohunice NPP in 2006 and 2008, which is compared with the Program of safety improvement of these reactors are discussed. Author and Slovak Nuclear Society accept gladly the suggestion of government of the Slovak Republic that they reassess this liability. The best alternative for decommissioned Jaslovske Bohunice NPP will be the completion of the 3 rd and 4 th blocks of the Mochovce NPP

Long-lasting injection of solar energetic electrons into the heliosphere

Science.gov (United States)

Dresing, N.; Gómez-Herrero, R.; Heber, B.; Klassen, A.; Temmer, M.; Veronig, A.

2018-05-01

Context. The main sources of solar energetic particle (SEP) events are solar flares and shocks driven by coronal mass ejections (CMEs). While it is generally accepted that energetic protons can be accelerated by shocks, whether or not these shocks can also efficiently accelerate solar energetic electrons is still debated. In this study we present observations of the extremely widespread SEP event of 26 Dec 2013 To the knowledge of the authors, this is the widest longitudinal SEP distribution ever observed together with unusually long-lasting energetic electron anisotropies at all observer positions. Further striking features of the event are long-lasting SEP intensity increases, two distinct SEP components with the second component mainly consisting of high-energy particles, a complex associated coronal activity including a pronounced signature of a shock in radio type-II observations, and the interaction of two CMEs early in the event. Aims: The observations require a prolonged injection scenario not only for protons but also for electrons. We therefore analyze the data comprehensively to characterize the possible role of the shock for the electron event. Methods: Remote-sensing observations of the complex solar activity are combined with in situ measurements of the particle event. We also apply a graduated cylindrical shell (GCS) model to the coronagraph observations of the two associated CMEs to analyze their interaction. Results: We find that the shock alone is likely not responsible for this extremely wide SEP event. Therefore we propose a scenario of trapped energetic particles inside the CME-CME interaction region which undergo further acceleration due to the shock propagating through this region, stochastic acceleration, or ongoing reconnection processes inside the interaction region. The origin of the second component of the SEP event is likely caused by a sudden opening of the particle trap.

Moessbauer determination of magnetic structure of Fe/sub 3/BO/sub 6/ crystal

Energy Technology Data Exchange (ETDEWEB)

Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

1984-10-01

The magnetic structure of a Fe/sub 3/BO/sub 6/ crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer ..gamma..-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV ..gamma..-quanta from the Fe/sub 3/BO/sub 6/ monocrystal has been studied experimentally. A high sensitivity of the interference of ..gamma..-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe/sub 3/BO/sub 6/. Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail.

Hydro energetic inventory study from Chapecozinho river

International Nuclear Information System (INIS)

Pimenta, S.C.; Sureck, M.A.A.; Nascimento, P.R.; Kawasaki, M.; Silva Felipe, R. da.

1990-01-01

The Hydro energetic Inventory Study in Chapecozinho River Basin, Brazil is described, comparing the proposed results in 1979 with the actual review in 1989. An analysis for solution the socio-economic and environment problems is also presented. (author)

Ultrafast Vibrational Spectrometer for Engineered Nanometric Energetic Materials

National Research Council Canada - National Science Library

Dlott, Dana

2002-01-01

The proposer requested funding for laser equipment that would be used to study engineered nanometric energetic materials consisting of nanometer metal particles, passivation layers and oxidizing binders...

The composition of corotating energetic particle streams

International Nuclear Information System (INIS)

McGuire, R.E.; von Rosenvinge, T.T.; McDonald, F.B.

1978-01-01

The relative abundances of 1.5--23 MeV per nucleon ions in corotating nucleon streams are compared with ion abundances in particle events associated with solar flares and with solar and solar wind abundances. He/O and C/O ratios are found to be a factor of the order 2--3 greater in corotating streams than in flare-associated events. The distribution of H/He ratios in corotating streams is found to be much narrower and of lower average value than in flare-associated events. H/He in corotating energetic particle streams compares favorably in both lack of variability and numerical value with H/He in high-speed solar wind plasma streams. The lack of variability suggests that the source population for the corotating energetic particles is the solar wind, a suggestion consistent with acceleration of the corotating particles in interplanetary space

Green colorants based on energetic azole borates.

Science.gov (United States)

Glück, Johann; Klapötke, Thomas M; Rusan, Magdalena; Stierstorfer, Jörg

2014-11-24

The investigation of green-burning boron-based compounds as colorants in pyrotechnic formulations as alternative for barium nitrate, which is a hazard to health and to the environment, is reported. Metal-free and nitrogen-rich dihydrobis(5-aminotetrazolyl)borate salts and dihydrobis(1,3,4-triazolyl)borate salts have been synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and vibrational spectroscopy. Their thermal and energetic properties have been determined as well. Several pyrotechnic compositions using selected azolyl borate salts as green colorants were investigated. Formulations with ammonium dinitramide and ammonium nitrate as oxidizers and boron and magnesium as fuels were tested. The burn time, dominant wavelength, spectral purity, luminous intensity, and luminous efficiency as well as the thermal and energetic properties of these compositions were measured. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural-energetic interpretation of competition between complex forms in the UBr3-MBr systems

International Nuclear Information System (INIS)

Suglobova, I.G.; Chirkst, D.Eh.

1978-01-01

The calorimetric method has been used for determining standard enthalpy values of the formation of bromouranates of alkali metals (M 2 UBr 5 ) and for checking the enthalpy value of the uranium tribromide formation. ΔH 0 of UBr 3 formation is -182.2+-0.5 kcal/mol. Enthalpies of the formation of pentabromouranates from binary bromides (and from simple substances) are: -6.6(-384.3) for K 2 VBr 5 , -9.7(-390.9) for Rb 2 VBr 5 , -10.21(-395.0) kcal/mol for Cs 2 VBr 5 . The error is +-0.5(+-10) kcal/mol. For Cs 3 VBr 6 the enthalpy of the formation is -10+-2 (-496+-3) kcal/mol. The M 2 VBr 5 compounds have rhombic lattices of the Tl 2 AlF 5 type. Sizes of elementary cells and uranium-alkali metal distances in polycrystals of the complexes have been determined on the base of X-ray diffraction patterns. Obtained picnometric densities of 4.51 (M=K), 4.79 (M=Rb), and 4.86+-0.01 g/cm 3 (M=Cs) agree with calculated values. The energy of the V(3)-Br bond is 53+-2 kcal/mol when the uranium coordination number equals 6. A new method has been proposed for evaluating the energy of the crystal lattice of the complexes by interionic distance with the aid of linear extrapolation of expeimental data for binary compounds in logarythmic coordinates. The relationship has been shown between the values and the nature of outer-spherical energetic effects and crystal structure of the complexes

The Catalytic Conversion of Thiophenes over Large H-ZSM-5 Crystals: An X-Ray, UV/Vis, and Fluorescence Microspectroscopic Study

NARCIS (Netherlands)

Kox, M.H.F.; Mijovilovich, A.E.; S ättler, J.J.H.B.; Stavitski, I.; Weckhuysen, B.M.

2013-01-01

X-ray absorption, UV/Vis, and fluorescence microspectroscopy have been used to characterize the catalytic conversion of thiophene derivatives within the micropores of an individual H-ZSM-5 zeolite crystal. Space-resolved information into the Si/ Al ratios and sulfur content was provided by X-ray

The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Kraus, D.; Barbrel, B.; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Vorberger, J. [Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden (Germany); Helfrich, J.; Frydrych, S.; Ortner, A.; Otten, A.; Roth, F.; Schaumann, G.; Schumacher, D.; Siegenthaler, K.; Wagner, F.; Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt (Germany); Gericke, D. O.; Wünsch, K. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Bachmann, B.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Bagnoud, V.; Blažević, A. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); and others

2015-05-15

We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

Using high-intensity laser-generated energetic protons to radiograph directly driven implosions

International Nuclear Information System (INIS)

Zylstra, A. B.; Li, C. K.; Rinderknecht, H. G.; Seguin, F. H.; Petrasso, R. D.; Stoeckl, C.; Meyerhofer, D. D.; Nilson, P.; Sangster, T. C.; Le Pape, S.; Mackinnon, A.; Patel, P.

2012-01-01

The recent development of petawatt-class lasers with kilojoule-picosecond pulses, such as OMEGA EP [L. Waxer et al., Opt. Photonics News 16, 30 (2005)], provides a new diagnostic capability to study inertial-confinement-fusion (ICF) and high-energy-density (HED) plasmas. Specifically, petawatt OMEGA EP pulses have been used to backlight OMEGA implosions with energetic proton beams generated through the target normal sheath acceleration (TNSA) mechanism. This allows time-resolved studies of the mass distribution and electromagnetic field structures in ICF and HED plasmas. This principle has been previously demonstrated using Vulcan to backlight six-beam implosions [A. J. Mackinnon et al., Phys. Rev. Lett. 97, 045001 (2006)]. The TNSA proton backlighter offers better spatial and temporal resolution but poorer spatial uniformity and energy resolution than previous D 3 He fusion-based techniques [C. Li et al., Rev. Sci. Instrum. 77, 10E725 (2006)]. A target and the experimental design technique to mitigate potential problems in using TNSA backlighting to study full-energy implosions is discussed. The first proton radiographs of 60-beam spherical OMEGA implosions using the techniques discussed in this paper are presented. Sample radiographs and suggestions for troubleshooting failed radiography shots using TNSA backlighting are given, and future applications of this technique at OMEGA and the NIF are discussed.

Three-dimensional Mesoscale Simulations of Detonation Initiation in Energetic Materials with Density-based Kinetics

Science.gov (United States)

Jackson, Thomas; Jost, A. M.; Zhang, Ju; Sridharan, P.; Amadio, G.

2017-06-01

In this work we present three-dimensional mesoscale simulations of detonation initiation in energetic materials. We solve the reactive Euler equations, with the energy equation augmented by a power deposition term. The reaction rate at the mesoscale is modelled using a density-based kinetics scheme, adapted from standard Ignition and Growth models. The deposition term is based on previous results of simulations of pore collapse at the microscale, modelled at the mesoscale as hot-spots. We carry out three-dimensional mesoscale simulations of random packs of HMX crystals in a binder, and show that the transition between no-detonation and detonation depends on the number density of the hot-spots, the initial radius of the hot-spot, the post-shock pressure of an imposed shock, and the amplitude of the power deposition term. The trends of transition at lower pressure of the imposed shock for larger number density of pore observed in experiments is reproduced. Initial attempts to improve the agreement between the simulation and experiments through calibration of various parameters will also be made.

Simulations of the polarisation-dependent Raman intensity of β-carotene in photosystem II crystals

International Nuclear Information System (INIS)

Brose, K.; Zouni, A.; Müh, F.; Mroginski, M.A.; Maultzsch, J.

2013-01-01

Highlights: • First polarisation-dependent Raman spectroscopy on photosystem II crystals. • Orientation-dependent Raman intensity simulations for di- and monomeric crystals. • Simulations account for all β-carotenes (β-Car) in the unit cell for the first time. • Prediction for identificationy of the β-Car cation in side-path electron transport. - Abstract: In order to clarify possibilities to identify the β-carotene (β-Car) radicals in secondary electron transfer (ET) reactions in the photosystem II core complex (PSIIcc), Raman intensities of all 96 β-Car cofactors in the unit cell of PSIIcc-dimer crystals as a function of polarisation and crystal orientation were simulated based on the 2.9 Å resolution structure. The Raman-active symmetry A g in the C 2h group is assigned to the β-Car modes ν 66 and ν 67 . Simulations are in agreement with experiment for off-resonant excitation at 1064 nm. Resonant measurements at 476 and 532 nm excitation can not be explained, which is attributed to mode mixing in the excited state and the existence of different spectral pools. The identity of the β-Car oxidised in secondary ET can not be resolved by Raman measurements on PSIIcc-dimer crystals. Additional simulations show that similar measurements on PSIIcc-monomer crystals could provide a possible route to solve this issue

Simulations of the polarisation-dependent Raman intensity of β-carotene in photosystem II crystals

Energy Technology Data Exchange (ETDEWEB)

Brose, K., E-mail: katharina.brose@gmx.net [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin (Germany); Zouni, A. [Institut für Chemie, Max-Volmer-Laboratorium, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Müh, F. [Institut für Theoretische Physik, Johannes Kepler Universität Linz, Altenberger Straße 69, 4040 Linz (Austria); Mroginski, M.A. [Institut für Chemie, Max-Volmer-Laboratorium, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Maultzsch, J. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin (Germany)

2013-06-03

Highlights: • First polarisation-dependent Raman spectroscopy on photosystem II crystals. • Orientation-dependent Raman intensity simulations for di- and monomeric crystals. • Simulations account for all β-carotenes (β-Car) in the unit cell for the first time. • Prediction for identificationy of the β-Car cation in side-path electron transport. - Abstract: In order to clarify possibilities to identify the β-carotene (β-Car) radicals in secondary electron transfer (ET) reactions in the photosystem II core complex (PSIIcc), Raman intensities of all 96 β-Car cofactors in the unit cell of PSIIcc-dimer crystals as a function of polarisation and crystal orientation were simulated based on the 2.9 Å resolution structure. The Raman-active symmetry A{sub g} in the C{sub 2h} group is assigned to the β-Car modes ν{sub 66} and ν{sub 67}. Simulations are in agreement with experiment for off-resonant excitation at 1064 nm. Resonant measurements at 476 and 532 nm excitation can not be explained, which is attributed to mode mixing in the excited state and the existence of different spectral pools. The identity of the β-Car oxidised in secondary ET can not be resolved by Raman measurements on PSIIcc-dimer crystals. Additional simulations show that similar measurements on PSIIcc-monomer crystals could provide a possible route to solve this issue.

Progress Towards a Benchtop Energetics Capability (BRIEFING CHARTS)

National Research Council Canada - National Science Library

Fajardo, Mario E; Lewis, William K

2006-01-01

The incorporation of nanometric (sub-micron size) metal fuel and oxidizer particles into energetic materials is a promising approach to increasing significantly the systems-level performance of munitions...

Reflections on assumption of energetic politics. Viewpoint of a sceptial observer

International Nuclear Information System (INIS)

Taczanowski, S.; Pohorecki, W.

2000-01-01

The Polish assumptions of energetic politics up to 2020 have been critically assessed. Energy sources availability as well as predicted fuel prices have been discussed for interesting period. Fossil fuels and uranium have been taken into account. On the presented basis it has been concluded that rejection the nuclear option in Poland for energetics development plans up to 2020 seems to be a serious mistake

Structure and function of proteins investigated by crystallographic and spectroscopic time-resolved methods

Science.gov (United States)

Purwar, Namrta

crystal. Time-resolved X-ray data collected at pH's of 4, 7 and 9 demonstrate that pH alters the kinetics of the PYP photocycle dramatically. At pH 4 the photocycle lasts almost one order of magnitude longer in time compared to pH 7. The final intermediate that accumulates at both pH 7 and pH 4 is absent at pH 9. Results from the dose- and the pH-dependent time-resolved crystallographic experiments show that it is imperative to carefully control the conditions under which time-resolved data are collected. With these considerations we collected a comprehensive time-series from nanoseconds to seconds at 14 different temperature settings from -40 °C to 70 °C. Results from time-resolved crystallography are corroborated by employing time-resolved absorption spectroscopy. For this, absorption spectra on crystals and solution are collected by a fast micro-spectrophotometer custom-designed in our lab. We identify kinetic phases of the PYP photocycle at all 14 temperature settings. Relaxation times associated with these phases are temperature-dependent and can be fit by the Van't Hoff-Arrhenius equation. Kinetic modeling yields entropy and enthalpy values at the barriers of the activation solely from the time-resolved crystallographic data. With this, we advance crystallography to a new frontier: the determination of free energy surfaces. Investigating enzymatic reactions can be challenging, because they are non-cyclic. After one turnover product must be washed away and substrate must be reloaded. A promising approach for routine application can be envisioned at the new 4th generation X-ray sources, such as X-ray free electron lasers (XFELs). With our results we set the scene to comprehensively investigate all kinds of enzymatic reactions with these instruments.

The use of quasi-isothermal modulated temperature differential scanning calorimetry for the characterization of slow crystallization processes in lipid-based solid self-emulsifying systems.

Science.gov (United States)

Otun, Sarah O; Meehan, Elizabeth; Qi, Sheng; Craig, Duncan Q M

2015-04-01

Slow or incomplete crystallization may be a significant manufacturing issue for solid lipid-based dosage forms, yet little information is available on this phenomenon. In this investigation we suggest a novel means by which slow solidification may be monitored in Gelucire 44/14 using quasi-isothermal modulated temperature DSC (QiMTDSC). Conventional linear heating and cooling DSC methods were employed, along with hot stage microscopy (HSM), for basic thermal profiling of Gelucire 44/14. QiMTDSC experiments were performed on cooling from the melt, using a range of incremental decreases in temperature and isothermal measurement periods. DSC and HSM highlighted the main (primary) crystallization transition; solid fat content analysis and kinetic analysis were used to profile the solidification process. The heat capacity profile from QiMTDSC indicated that after an initial energetic primary crystallisation, the lipid underwent a slower period of crystallization which continued to manifest at much lower temperatures than indicated by standard DSC. We present evidence that Gelucire 44/14 undergoes an initial crystallization followed by a secondary, slower process. QIMTDSC appears to be a promising tool in the investigation of this secondary crystallization process.

Spectrophotometric and chromatographic determination of insensitive energetic materials: HNS and NTO, in the presence of sensitive nitro-explosives.

Science.gov (United States)

Can, Ziya; Uzer, Ayşem; Tekdemir, Yasemin; Erçağ, Erol; Türker, Lemi; Apak, Reşat

2012-02-15

As there are no molecular spectroscopic determination methods for the most widely used insensitive energetic materials, 2,2',4,4',6,6'-hexanitrostilbene (HNS) and 3-nitro-1,2,4-triazole-5-one (NTO), in the presence of sensitive nitro-explosives, two novel spectrophotometric methods were developed. For HNS and TNT mixtures, both analytes react with dicyclohexylamine (DCHA) forming different colored charge-transfer complexes, which can be resolved by derivative spectroscopy. The spectrophotometric method for NTO measures the 416-nm absorbance of its yellow-colored Na(+)NTO(-) salt formed with NaOH. TNT, if present, is pre-extracted into IBMK as its Meisenheimer anion forming an ion-pair with the cationic surfactant cetyl pyridinium (CP(+)) in alkaline medium, whereas the unextracted NTO is determined in the aqueous phase. The molar absorptivity (ε, L mol(-1)cm(-1)) and limit of quantification (LOQ, mg L(-1)) are as follows: for HNS, ε=2.75 × 10(4) and LOQ=0.48 (in admixture with TNT); for NTO, ε=6.83 × 10(3) and LOQ=0.73. These methods were not affected from nitramines and nitrate esters in synthetic mixtures or composite explosives. The developed methods were statistically validated against HPLC, and the existing chromatographic method was modified so as to enable NTO determination in the presence of TNT. These simple, low-cost, and versatile methods can be used in criminology, remediation/monitoring of contaminated sites, and kinetic stability modeling of munitions containing desensitized energetic materials. Copyright © 2012 Elsevier B.V. All rights reserved.

Kinetic and energetic analysis of lipid accumulation in batch culture of Rhodotorula glutinis

Energy Technology Data Exchange (ETDEWEB)

Pan, J.G.; Rhee, J.S.

1986-01-01

Kinetic and energetic analyses were made to describe the accumulation of lipid Rhodotorula glutinis more quantitatively. Accumulation of lipid in yeast was controlled by kinetic factors. The energetic efficiency of lipid formation was higher than that of growth. 18 references.

Probing the Dynamics of Ultra-Fast Condensed State Reactions in Energetic Materials

Science.gov (United States)

Piekiel, Nicholas William

2012-01-01

Energetic materials (EMs) are substances with a high amount of stored energy and the ability to release that energy at a rapid rate. Nanothermites and green organic energetics are two classes of EMs which have gained significant interest as they each have desirable properties over traditional explosives. These systems also possess downfalls, which…

Effect of Neoclassical Transport Optimization on Energetic Ion Confinement in LHD

International Nuclear Information System (INIS)

Murakami, S.; Yamada, H.; Sasao, M.

2004-01-01

Confinement of energetic ions from neutral beam injection heating is investigated by changing the magnetic field configuration of the Large Helical Device from a classical heliotron configuration to an optimized neoclassical transport configuration to a level typical of ''advanced stellarators.'' The experimental results show the highest count rate of fast neutral particles not in the optimized configuration but in the inward-shifted one. The GNET simulation results show a relatively good agreement with the experimental results, and they also show a lower energy loss rate in the optimized configuration. This contradiction can be explained by the radial profile of the energetic ions. The relatively good agreement between experimental and simulation results suggest that ripple transport (neoclassical) dominates the energetic ion confinement and that the optimization process is effective in improving confinement in helical systems

MESSENGER observations of transient bursts of energetic electrons in Mercury's magnetosphere.

Science.gov (United States)

Ho, George C; Krimigis, Stamatios M; Gold, Robert E; Baker, Daniel N; Slavin, James A; Anderson, Brian J; Korth, Haje; Starr, Richard D; Lawrence, David J; McNutt, Ralph L; Solomon, Sean C

2011-09-30

The MESSENGER spacecraft began detecting energetic electrons with energies greater than 30 kilo-electron volts (keV) shortly after its insertion into orbit about Mercury. In contrast, no energetic protons were observed. The energetic electrons arrive as bursts lasting from seconds to hours and are most intense close to the planet, distributed in latitude from the equator to the north pole, and present at most local times. Energies can exceed 200 keV but often exhibit cutoffs near 100 keV. Angular distributions of the electrons about the magnetic field suggest that they do not execute complete drift paths around the planet. This set of characteristics demonstrates that Mercury's weak magnetic field does not support Van Allen-type radiation belts, unlike all other planets in the solar system with internal magnetic fields.

THE EFFECT OF EXTERNAL TRANSPORT ON ENERGETIC EFFICIENCY OF BIODIESEL PRODUCTION

Directory of Open Access Journals (Sweden)

Olga Anna Orynycz

2017-03-01

Full Text Available In several our publications energetic efficiency of biofuel production was defined as a ratio of the amount of energy obtained in a form of biofuel to the sum of energy contributions necessary to conduct production processes on all the production stages. It was also shown that such a definition enables subsequent inclusion of production steps due to additivity of reciprocals of energetic efficiency determined separately for each step. In the present work, several scenarios of the transport of biomass between plantation and industrial facility converting biomass into biofuel are considered, appropriate values of energetic efficiency are computed and compared. The analysis is confined to biodiesel production based on rapeseed. The results show substantial differences caused by various approaches to that stage of transport.

Solar Energetic Particle Studies with PAMELA

Science.gov (United States)

Bravar, U.; Christian, E. R.; deNolfo, Georgia; Ryan, J. M.; Stochaj, S.

2011-01-01

The origin of the high-energy solar energetic particles (SEPs) may conceivably be found in composition signatures that reflect the elemental abundances of the low corona and chromosphere vs. the high corona and solar wind. The presence of secondaries, such as neutrons and positrons, could indicate a low coronal origin of these particles. Velocity dispersion of different species and over a wide energy range can be used to determine energetic particle release times at the Sun. Together with multi-wavelength imaging, in- situ observations of a variety of species, and coverage over a wide energy range provide a critical tool in identifying the origin of SEPs, understanding the evolution of these events within the context of solar active regions, and constraining the acceleration mechanisms at play. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA)instrument, successfully launched in 2006 and expected to remain operational until at least the beginning of 2012, measures energetic particles in the same energy range as ground-based neutron monitors, and lower energies as well. It thus bridges the gap between low energy in-situ observations and ground-based Ground Level Enhancements (GLE) observations. It can measure the charge (up to Z=6) and atomic number of the detected particles, and it can identify and measure positrons and detect neutrons-an unprecedented array of data channels that we can bring to bear on the origin of high-energy SEPs. We present prelimiary results on the for the 2006 December 13 solar flare and GLE and the 2011 March 21 solar flare, both registering proton and helium enhancements in PAMELA. Together with multi- spacecraft contextual data and modeling, we discuss the PAMELA results in the context of the different acceleration mechanisms at play.

Kinetic Simulation and Energetic Neutral Atom Imaging of the Magnetosphere

Science.gov (United States)

Fok, Mei-Ching H.

2011-01-01

Advanced simulation tools and measurement techniques have been developed to study the dynamic magnetosphere and its response to drivers in the solar wind. The Comprehensive Ring Current Model (CRCM) is a kinetic code that solves the 3D distribution in space, energy and pitch-angle information of energetic ions and electrons. Energetic Neutral Atom (ENA) imagers have been carried in past and current satellite missions. Global morphology of energetic ions were revealed by the observed ENA images. We have combined simulation and ENA analysis techniques to study the development of ring current ions during magnetic storms and substorms. We identify the timing and location of particle injection and loss. We examine the evolution of ion energy and pitch-angle distribution during different phases of a storm. In this talk we will discuss the findings from our ring current studies and how our simulation and ENA analysis tools can be applied to the upcoming TRIO-CINAMA mission.

Mode structure symmetry breaking of energetic particle driven beta-induced Alfvén eigenmode

Science.gov (United States)

Lu, Z. X.; Wang, X.; Lauber, Ph.; Zonca, F.

2018-01-01

The mode structure symmetry breaking of energetic particle driven Beta-induced Alfvén Eigenmode (BAE) is studied based on global theory and simulation. The weak coupling formula gives a reasonable estimate of the local eigenvalue compared with global hybrid simulation using XHMGC. The non-perturbative effect of energetic particles on global mode structure symmetry breaking in radial and parallel (along B) directions is demonstrated. With the contribution from energetic particles, two dimensional (radial and poloidal) BAE mode structures with symmetric/asymmetric tails are produced using an analytical model. It is demonstrated that the symmetry breaking in radial and parallel directions is intimately connected. The effects of mode structure symmetry breaking on nonlinear physics, energetic particle transport, and the possible insight for experimental studies are discussed.

Report for MaRIE Drivers Workshop on needs for energetic material's studies.

Energy Technology Data Exchange (ETDEWEB)

Specht, Paul Elliott [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2018-01-01

Energetic materials (i.e. explosives, propellants, and pyrotechnics) have complex mesoscale features that influence their dynamic response. Direct measurement of the complex mechanical, thermal, and chemical response of energetic materials is critical for improving computational models and enabling predictive capabilities. Many of the physical phenomena of interest in energetic materials cover time and length scales spanning several orders of magnitude. Examples include chemical interactions in the reaction zone, the distribution and evolution of temperature fields, mesoscale deformation in heterogeneous systems, and phase transitions. This is particularly true for spontaneous phenomena, like thermal cook-off. The ability for MaRIE to capture multiple length scales and stochastic phenomena can significantly advance our understanding of energetic materials and yield more realistic, predictive models.

Status, problems and perspectives of the education on nuclear energetics and nuclear safety within the Technical University of Sofia

International Nuclear Information System (INIS)

Lakov, M.; Bonev, B.; Stoyanov, S.; Velev, V.

2004-01-01

Education on nuclear energetic within the Technical University of Sofia is conducted since 1966 within the framework of the specialty 'Thermal energetic' at that time, and since 1973, within the specialty 'Thermal and nuclear energetic'. In 1986 is opened a college on nuclear energetic teaching on specialty 'Nuclear Energetic' and 'Automation in Energetic'. Since 1998 the department 'Thermal and nuclear energetic' is the only one within the Republic of Bulgaria having the legal rights to train 'engineers-bachelors' and 'engineers-master of science' on 'Thermal and nuclear energetic', as well as doctors - engineers of the same specialty. The bachelor course is graduated from between 40 and 60 students annually. The training within the bachelor level is 4 years and finishes by defending diploma thesis. Part of the graduated bachelors (between 20 and 30 students) are closely specialized in the area of Nuclear Energetic. The specialization is trained through preparation of diploma thesis within the nuclear area. The master course has 3 semesters including preparation of diploma thesis. Within the master level are prepared 25 students annually. Within the sub-division 'Nuclear Energetic' are promulgated between 2 and 4 competitions for preparation of doctoral thesis annually. At the moment 7 students are preparing doctoral thesis. Graduated engineers on 'Nuclear Energetic' are engaged as operative personnel mainly in Kozloduy NPP. The rest of them are engaged within the engineering and scientific organizations, connected to nuclear energetic

A new method for determining gas phase heat of formation of aromatic energetic compounds

Energy Technology Data Exchange (ETDEWEB)

Keshavarz, Mohammad H. [Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr P. O. Box 83145/115 (Iran); Tehrani, Masoud K. [Department of Physics, Malek-ashtar University of Technology, Shahin-shahr P. O. Box 83145/115 (Iran)

2007-04-15

A new correlation is introduced for desk calculation of gas phase heat of formation of aromatic energetic compounds that contain the elements of carbon, hydrogen, nitrogen and oxygen. Predicted gas phase heats of formation for 26 energetic compounds have a root mean square of deviation from experiment of 20.67 kJ/mol, which is in good agreement with respect to measured values of oxygen-lean and oxygen-rich aromatic energetic compounds. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Numerical analysis of energetic particle stabilization of ballooning modes in finite-aspect-ratio tokamaks

International Nuclear Information System (INIS)

He Qibing; Peng Qiyang; Qu Wenxiao

1993-09-01

The effect of energetic trapped particles on the stabilization of ballooning modes in finite-aspect-ratio tokamaks is numerically analyzed. The numerical solution of boundary value problem of an integro-differential equation is successfully obtained by RKF integral method with variable step size. The results show that the instability domain of ballooning modes becomes small along with the increase of energetic particles pressure. The energetic trapped particles can partially or completely suppress the instability of ballooning modes

Collective phenomena with energetic particles in fusion plasmas

International Nuclear Information System (INIS)

Breizman, B.N.; Berk, H.L.; Candy, J.

2001-01-01

Recent progress in the theory of collective modes driven by energetic particles, as well as interpretations of fast particle effects observed in fusion-related experiments, are described. New developments in linear theory include: (a) Alfven-mode frequency gap widening due to energetic trapped ions, (b) interpretation of JET results for plasma pressure effect on TAE modes, and (c) ''counter'' propagation of TAE modes due to trapped fast ion anisotropy. The new nonlinear results are: (a) theoretical explanation for the pitchfork splitting effect observed in TAE experiments on JET, (b) existence of coherent structures with strong frequency chirping due to kinetic instability, (c) self-consistent nonlinear theory for fishbone instabilities, and (d) intermittent quasilinear diffusion model for anomalous fast particle losses. (author)

Collective phenomena with energetic particles in fusion plasmas

International Nuclear Information System (INIS)

Breizman, B.N.; Berk, H.L.; Candy, J.

1999-01-01

Recent progress in the theory of collective modes driven by energetic particles, as well as interpretations of fast particle effects observed in fusion-related experiments, are described. New developments in linear theory include: (a) Alfven-mode frequency gap widening due to energetic trapped ions, (b) interpretation of JET results for plasma pressure effect on TAE modes, and (c) 'counter' propagation of TAE modes due to trapped fast ion anisotropy. The new nonlinear results are: (a) theoretical explanation for the pitchfork splitting effect observed in TAE experiments on JET, (b) existence of coherent structures with strong frequency chirping due to kinetic instability, (c) self-consistent nonlinear theory for fishbone instabilities, and (d) intermittent quasilinear diffusion model for anomalous fast particle losses. (author)

Erosion tests of materials by energetic particle beams

Energy Technology Data Exchange (ETDEWEB)

Schechter, D.E.; Tsai, C.C.; Sluss, F.; Becraft, W.R.; Hoffman, D.J.

1985-01-01

The internal components of magnetic fusion devices must withstand erosion from and high heat flux of energetic plasma particles. The selection of materials for the construction of these components is important to minimize contamination of the plasma. In order to study various materials' comparative resistance to erosion by energetic particles and their ability to withstand high heat flux, water-cooled copper swirl tubes coated or armored with various materials were subjected to bombardment by hydrogen and helium particle beams. Materials tested were graphite, titanium carbide (TiC), chromium, nickel, copper, silver, gold, and aluminum. Details of the experimental arrangement and methods of application or attachment of the materials to the copper swirl tubes are presented. Results including survivability and mass losses are discussed.

Energetic particles and ionization in the nighttime middle and low latitude ionosphere

International Nuclear Information System (INIS)

Voss, H.D.; Smith, L.G.

1977-01-01

Seven Nike Apache rockets, each equipped with an energetic particle spectrometer (12 E 80 keV) and electron-density experiments, were launched from Wallops Island, Virginia and Chilca, Peru, under varying geomagnetic conditions near midnight. At Wallops Island the energetic particle flux (E 40 keV) is found to be strongly dependent on Kp. The pitch-angle distribution is asymmetrical about a peak at 90 D signifying a predominately quasi-trapped flux and explaining the linear increase of count rate with altitute in the altitude region 120 to 200 km. The height-averaged ionization rates derived from the electron-density profiles are consistent with the rates calculated from the observed total particle flux for magnetic index Kp 3. In the region 90 to 110 km it is found that the nighttime ionization is primarily a result of Ly-beta radiation from the geocorona and interplanetary hydrogen for even very disturbed conditions. Below 90 km during rather disturbed conditions energetic electrons can be a significant ionization source. Two energetic particle precipitation zones have been identified at midlatitudes

Energetic particles and ionization in the nighttime middle and low latitude ionosphere

Science.gov (United States)

Voss, H. D.; Smith, L. G.

1977-01-01

Seven Nike Apache rockets, each equipped with an energetic particle spectrometer (12 E 80 keV) and electron-density experiments, were launched from Wallops Island, Virginia and Chilca, Peru, under varying geomagnetic conditions near midnight. At Wallops Island the energetic particle flux (E 40 keV) is found to be strongly dependent on Kp. The pitch-angle distribution is asymmetrical about a peak at 90 D signifying a predominately quasi-trapped flux and explaining the linear increase of count rate with altitute in the altitude region 120 to 200 km. The height-averaged ionization rates derived from the electron-density profiles are consistent with the rates calculated from the observed total particle flux for magnetic index Kp 3. In the region 90 to 110 km it is found that the nighttime ionization is primarily a result of Ly-beta radiation from the geocorona and interplanetary hydrogen for even very disturbed conditions. Below 90 km during rather disturbed conditions energetic electrons can be a significant ionization source. Two energetic particle precipitation zones have been identified at midlatitudes.

Energetic utilization of dietary fiber in pigs

NARCIS (Netherlands)

Rijnen, M.M.J.A.

2003-01-01

The energetic utilization of fermentable dietary fiber (fDF) of different fiber sources and its relation to physical activity and housing conditions was studied in three experiments. In all experiments the daily intake of digestible nutrients, nitrogen and energy balances, heat production, and

Scintillation response of CsI: Tl crystal under neutron, gamma, alpha particles and beta excitations

Energy Technology Data Exchange (ETDEWEB)

Pereira, Maria da Conceicao Costa; Madi Filho, Tufic; Lopes, Valdir Maciel; Berretta, Jose Roberto; Cardenas, Jose Patricio Nahuel, E-mail: macoper@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Among the converters of X and gamma radiation in light photons, known as scintillators, the one which is the most efficient emits photons with a wavelength near 400 nm. Particularly, among them, the cesium iodine doped with thallium (CsI:Tl) crystal is that which matches better between the light emission spectrum (peak at 540 nm) and the quantum sensitivity curve of the photodiodes and CCD (Charge Coupled Device). This explains the renewed interest in using this crystal as scintillator. Although the CsI:Tl crystal is commercially available, its local development would give the possibility to obtain it in different geometric configurations and coupling. Moreover, there is a special interest in studying new conditions that will alter the properties of this crystal in order to achieve a optimal level of its functional characteristics. Having an efficient national scintillator with low cost is a strategic opportunity to study the response of a detector applied to different types of radiation. The crystal of cesium iodide activated with thallium (CsI:Tl) has a high gamma detection efficiency per unit volume. In this paper, the CsI:Tl crystal, grown by the vertical Bridgman technique in evacuated silica ampoules and with the purpose of use as radiation detectors, is described. To evaluate the scintillator, measures of the thallium distribution in the crystal volume were taken, with overall efficiency score. The scintillator response was studied through gamma radiation from sources of {sup 137}Cs, {sup 60}Co, {sup 22}Na, {sup 54}Mn, {sup 131}I and {sup 99m}Tc; the beta radiation from source of {sup 90}Sr/{sup 90}Y, alpha particles from {sup 241}Am source and the scintillator response to neutrons from Am/Be source. The energetic resolution for {sup 137}Cs gamma rays (662 keV) was 10%. The results showed the validity of using the CsI:Tl crystal developed in our laboratory, in many applications in the area of radiation detectors. (author)