The Microstructure and Gamma Prime Distributions in Inertia Friction Welded Joint of P/M Superalloy FGH96

NASA Astrophysics Data System (ADS)

Zhang, Chi; Shen, Wenfei; Zhang, Liwen; Xia, Yingnan; Li, Ruiqin

2017-04-01

A gamma prime ( γ') precipitation ( 35% in volume)-hardened powder metallurgy (P/M) superalloy FGH96 was welded using inertia friction welding (IFW). The microstructure and γ' distributions in the joints in two conditions, hot isostatic pressed state and solution-treated and aged state, were characterized. The recrystallization of grains, the dissolution and re-precipitation of γ' in the joints were discussed in terms of the temperature evolutions which were calculated by finite element model analysis. Regardless of the initial states, fully recrystallized fine grain structure formed at welded zone. Meanwhile, very fine γ' precipitations were re-precipitated at the welded zone. These recrystallized grain structure and fine re-precipitated γ' resulted in increasing hardness of IFW joint while making the hardness dependent on the microstructure and γ' precipitation.

Luminescence and Absorption Spectra of C sub 60 Films

DTIC Science & Technology

1991-02-01

J. McKeirnan, J.L Zink, R. Stanley Williams, W.M. Tong, D.A.A. Ohlberg and R.L. Whetten Submitted t DTIC Physical Review Letters ELECT E SFEB 2? 7,19...range at 20K. A 1400 cm"& progression in the a soccerball inflation mode is observed. The low-temperature absorption spectrum exhibits similar fine...ag soccerball inflation mode is observed. The low temperature absorption spectrum exhibits similar fine structure. The characterization of vibronic

Capturing local structure modulations of photoexcited BiVO4 by ultrafast transient XAFS.

PubMed

Uemura, Yohei; Kido, Daiki; Koide, Akihiro; Wakisaka, Yuki; Niwa, Yasuhiro; Nozawa, Shunsuke; Ichiyanagi, Kohei; Fukaya, Ryo; Adachi, Shin-Ichi; Katayama, Tetsuo; Togashi, Tadashi; Owada, Shigeki; Yabashi, Makina; Hatada, Keisuke; Iwase, Akihide; Kudo, Akihiko; Takakusagi, Satoru; Yokoyama, Toshihiko; Asakura, Kiyotaka

2017-06-29

Ultrafast excitation of photocatalytically active BiVO 4 was characterized by femto- and picosecond transient X-ray absorption fine structure spectroscopy. An initial photoexcited state (≪500 fs) changed to a metastable state accompanied by a structural change with a time constant of ∼14 ps. The structural change might stabilize holes on oxygen atoms since the interaction between Bi and O increases.

Solar Cycle Fine Structure and Surface Rotation from Ca II K-Line Time Series Data

NASA Technical Reports Server (NTRS)

Scargle, Jeff; Keil, Steve; Worden, Pete

2011-01-01

Analysis of three and a half decades of data from the NSO/AFRL/Sac Peak K-line monitoring program yields evidence for four components to the variation: (a) the solar cycle, with considerable fine structure and a quasi-periodicity of 122.4 days; (b) a stochastic process, faster than (a) and largely independent of it, (c) a quasi-periodic signal due to rotational modulation, and of course (d) observational errors (shown to be quite small). Correlation and power spectrum analyses elucidate periodic and aperiodic variation of these chromospheric parameters. Time-frequency analysis is especially useful for extracting information about differential rotation, and in particular elucidates the connection between its behavior and fine structure of the solar cycle on approximately one-year time scales. These results further suggest that similar analyses will be useful at detecting and characterizing differential rotation in stars from stellar light-curves such as those being produced at NASA's Kepler observatory.

Characterization of pentavalent and hexavalent americium complexes in nitric acid using X-ray absorption fine structure spectroscopy and first-principles modeling

DOE PAGES

Riddle, Catherine; Czerwinski, Kenneth; Kim, Eunja; ...

2016-01-18

We studied the speciation of pentavalent and hexavalent americium (Am) complexes in nitric acidicby X-ray absorption fine structure spectroscopy (XAFS), UV-visible spectroscopy, and density functional theory (DFT). Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) results were consistent with the presence of a mixture of AmO 2 + and AmO 2 2+ with only a small amount AmO 2 present. The resulting average bond distances we found were 1.71 Å for Am=O and 2.44 Å for Am-O. All-electron scalar relativistic calculations were also carried out using DFT to predict the equilibrium geometries and properties ofmore » the AmO 2 + and AmO 2 2+ aquo complexes. Calculated bond distances for the Am(VI) complex are in reasonable agreement with EXAFS data and the computed energy gaps between frontier molecular orbitals suggest a slightly higher kinetic stability and chemical hardness of Am(VI) compared to Am(V).« less

Changes in fine structure of pericytes and novel desmin-immunopositive perivascular cells during postnatal development in rat anterior pituitary gland.

PubMed

Jindatip, Depicha; Fujiwara, Ken; Horiguchi, Kotaro; Tsukada, Takehiro; Kouki, Tom; Yashiro, Takashi

2013-09-01

Pericytes are perivascular cells associated with capillaries. We previously demonstrated that pericytes, identified by desmin immunohistochemistry, produce type I and III collagens in the anterior pituitary gland of adult rats. In addition, we recently used desmin immunoelectron microscopy to characterize a novel type of perivascular cell, dubbed a desmin-immunopositive perivascular cell, in the anterior pituitary. These two types of perivascular cells differ in fine structure. The present study attempted to characterize the morphological features of pituitary pericytes and novel desmin-immunopositive perivascular cells during postnatal development, in particular their role in collagen synthesis. Desmin immunostaining revealed numerous perivascular cells at postnatal day 5 (P5) and P10. Transmission electron microscopy showed differences in the fine structure of the two cell types, starting at P5. Pericytes had well-developed rough endoplasmic reticulum and Golgi apparatus at P5 and P10. The novel desmin-immunopositive perivascular cells exhibited dilated cisternae of rough endoplasmic reticulum at P5-P30. In addition, during early postnatal development in the gland, a number of type I and III collagen-expressing cells were observed, as were high expression levels of these collagen mRNAs. We conclude that pituitary pericytes and novel desmin-immunopositive perivascular cells contain well-developed cell organelles and that they actively synthesize collagens during the early postnatal period.

Strength characterization of open-graded aggregates for structural backfills

DOT National Transportation Integrated Search

2015-06-01

Open-graded aggregates are common in road and bridge construction because they are easy to place, and they have the advantages of very low fine content, free-draining characteristics, low frost heave potential, and simple quality assurance testing. T...

Coupling fine-scale root and canopy structure using ground-based remote sensing

DOE PAGES

Hardiman, Brady S.; Gough, Christopher M.; Butnor, John R.; ...

2017-02-21

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation) at multiple spatialmore » scales 10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Lastly, our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.« less

Coupling fine-scale root and canopy structure using ground-based remote sensing

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

Hardiman, Brady S.; Gough, Christopher M.; Butnor, John R.

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation) at multiple spatialmore » scales 10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Lastly, our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.« less

Recent Advances in the Synthesis, Characterization and Application of Zn+-containing Heterogeneous Catalysts.

PubMed

Chen, Guangbo; Zhao, Yufei; Shang, Lu; Waterhouse, Geoffrey I N; Kang, Xiaofeng; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

2016-07-01

Monovalent Zn + (3d 10 4s 1 ) systems possess a special electronic structure that can be exploited in heterogeneous catalysis and photocatalysis, though it remains challenge to synthesize Zn + -containing materials. By careful design, Zn + -related species can be synthesized in zeolite and layered double hydroxide systems, which in turn exhibit excellent catalytic potential in methane, CO and CO 2 activation. Furthermore, by utilizing advanced characterization tools, including electron spin resonance, X-ray absorption fine structure and density functional theory calculations, the formation mechanism of the Zn + species and their structure-performance relationships can be understood. Such advanced characterization tools guide the rational design of high-performance Zn + -containing catalysts for efficient energy conversion.

Joint the active source and passive source seismic to research the fine crustal structure of the Lushan area

NASA Astrophysics Data System (ADS)

Chen, Q.; Yu, C.

2017-12-01

On April 20, 2013, Ms7.0 strong earthquake (Lushan earthquake) occurred in Lanshan County Ya'an City, Sichuan Province. It is another earthquake that occurred in the Longmenshan fault zone after the Wenchuan earthquake. However, there is still no conclusive conclusion in relationship between the fine structure of the Lushan area and triggering seismic fault . In this study, the crustal structure, the shallow structure and the hidden faults and the focal mechanism of the Lushan earthquake were analyzed by using the deep seismic reflection profile and the broadband seismic array data. Combined with the surface geological information, the structure and fracture cause of the Lishan earthquake were discussed.We have synthetic analyzed the seismic precursors, fine locating, focal mechanism analysis and time-tomographic imaging of the broadband seismic data before and after the earthquake in Lushan earthquake, and obtained the seismic distribution, the focal mechanism and the crustal fine structure in the Lushan area. And we use these results to detailed interpreted the deep reflection seismic section of the Lushan earthquake zone.The results show that the crust of the Lushan area is characterized by a distinct structure of upper crust with thickness about 14.75km. The nature of the faults is inferred to be thrusting in the region due to the pushing of the crustal material of the Tibetan plateau into the southeast part of the rigid Sichuan basin. The shuangshi-Dachuan fault stretches from the surface to the deep crust at a low angle, and is dominated by thrusting in a form of imbricate structure with small-scale faults nearby. Whereas the Guangyuan-Dayi fault is a positive flower structure with a listric shape, consisting of six branches. Its movement is dominated by thrusting with gentle horizontal slip.

Fine structure characterization of martensite/austenite constituent in low-carbon low-alloy steel by transmission electron forward scatter diffraction.

PubMed

Li, C W; Han, L Z; Luo, X M; Liu, Q D; Gu, J F

2016-11-01

Transmission electron forward scatter diffraction and other characterization techniques were used to investigate the fine structure and the variant relationship of the martensite/austenite (M/A) constituent of the granular bainite in low-carbon low-alloy steel. The results demonstrated that the M/A constituents were distributed in clusters throughout the bainitic ferrite. Lath martensite was the main component of the M/A constituent, where the relationship between the martensite variants was consistent with the Nishiyama-Wassermann orientation relationship and only three variants were found in the M/A constituent, suggesting that the variants had formed in the M/A constituent according to a specific mechanism. Furthermore, the Σ3 boundaries in the M/A constituent were much longer than their counterparts in the bainitic ferrite region. The results indicate that transmission electron forward scatter diffraction is an effective method of crystallographic analysis for nanolaths in M/A constituents. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Characterization and fine mapping of qkc7.03: a major locus for kernel cracking in maize.

PubMed

Yang, Mingtao; Chen, Lin; Wu, Xun; Gao, Xing; Li, Chunhui; Song, Yanchun; Zhang, Dengfeng; Shi, Yunsu; Li, Yu; Li, Yong-Xiang; Wang, Tianyu

2018-02-01

A major locus conferring kernel cracking in maize was characterized and fine mapped to an interval of 416.27 kb. Meanwhile, combining the results of transcriptomic analysis, the candidate gene was inferred. Seed development requires a proper structural and physiological balance between the maternal tissues and the internal structures of the seeds. In maize, kernel cracking is a disorder in this balance that seriously limits quality and yield and is characterized by a cracked pericarp at the kernel top and endosperm everting. This study elucidated the genetic basis and characterization of kernel cracking. Primarily, a near isogenic line (NIL) with a B73 background exhibited steady kernel cracking across environments. Therefore, deprived mapping populations were developed from this NIL and its recurrent parent B73. A major locus on chromosome 7, qkc7.03, was identified to be associated with the cracking performance. According to a progeny test of recombination events, qkc7.03 was fine mapped to a physical interval of 416.27 kb. In addition, obvious differences were observed in embryo development and starch granule arrangement within the endosperm between the NIL and its recurrent parent upon the occurrence of kernel cracking. Moreover, compared to its recurrent parent, the transcriptome of the NIL showed a significantly down-regulated expression of genes related to zeins, carbohydrate synthesis and MADS-domain transcription factors. The transcriptomic analysis revealed ten annotated genes within the target region of qkc7.03, and only GRMZM5G899476 was differently expressed between the NIL and its recurrent parent, indicating that this gene might be a candidate gene for kernel cracking. The results of this study facilitate the understanding of the potential mechanism underlying kernel cracking in maize.

Fluidized Bed Asbestos Sampler Design and Testing

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

Karen E. Wright; Barry H. O'Brien

A large number of samples are required to characterize a site contaminated with asbestos from previous mine or other industrial operations. Current methods, such as EPA Region 10’s glovebox method, or the Berman Elutriator method are time consuming and costly primarily because the equipment is difficult to decontaminate between samples. EPA desires a shorter and less costly method for characterizing soil samples for asbestos. The objective of this was to design and test a qualitative asbestos sampler that operates as a fluidized bed. The proposed sampler employs a conical spouted bed to vigorously mix the soil and separate fine particulatemore » including asbestos fibers on filters. The filters are then analyzed using transmission electron microscopy for presence of asbestos. During initial testing of a glass prototype using ASTM 20/30 sand and clay fines as asbestos surrogates, fine particulate adhered to the sides of the glass vessel and the tubing to the collection filter – presumably due to static charge on the fine particulate. This limited the fines recovery to ~5% of the amount added to the sand surrogate. A second prototype was constructed of stainless steel, which improved fines recovery to about 10%. Fines recovery was increased to 15% by either humidifying the inlet air or introducing a voltage probe in the air space above the sample. Since this was not a substantial improvement, testing using the steel prototype proceeded without using these techniques. Final testing of the second prototype using asbestos suggests that the fluidized bed is considerably more sensitive than the Berman elutriator method. Using a sand/tremolite mixture with 0.005% tremolite, the Berman elutriator did not segregate any asbestos structures while the fluidized bed segregated an average of 11.7. The fluidized bed was also able to segregate structures in samples containing asbestos at a 0.0001% concentration, while the Berman elutriator method did not detect any fibers at this concentration. Opportunities for improvement with the fluidized bed include improving reproducibility among replicates, increasing mass recovery, improving the lid gasket seal.« less

Statistical properties of exciton fine structure splitting and polarization angles in quantum dot ensembles

NASA Astrophysics Data System (ADS)

Gong, Ming; Hofer, B.; Zallo, E.; Trotta, R.; Luo, Jun-Wei; Schmidt, O. G.; Zhang, Chuanwei

2014-05-01

We develop an effective model to describe the statistical properties of exciton fine structure splitting (FSS) and polarization angle in quantum dot ensembles (QDEs) using only a few symmetry-related parameters. The connection between the effective model and the random matrix theory is established. Such effective model is verified both theoretically and experimentally using several rather different types of QDEs, each of which contains hundreds to thousands of QDs. The model naturally addresses three fundamental issues regarding the FSS and polarization angels of QDEs, which are frequently encountered in both theories and experiments. The answers to these fundamental questions yield an approach to characterize the optical properties of QDEs. Potential applications of the effective model are also discussed.

R-Matrix Analysis of Structures in Economic Indices: from Nuclear Reactions to High-Frequency Trading

NASA Astrophysics Data System (ADS)

Firk, Frank W. K.

2014-03-01

It is shown that the R-matrix theory of nuclear reactions is a viable mathematical theory for the description of the fine, intermediate and gross structure observed in the time-dependence of economic indices in general, and the daily Dow Jones Industrial Average in particular. A Lorentzian approximation to R-matrix theory is used to analyze the complex structures observed in the Dow Jones Industrial Average on a typical trading day. Resonant structures in excited nuclei are characterized by the values of their fundamental strength function, (average total width of the states)/(average spacing between adjacent states). Here, values of the ratios (average lifetime of individual states of a given component of the daily Dow Jones Industrial Average)/(average interval between the adjacent states) are determined. The ratios for the observed fine and intermediate structure of the index are found to be essentially constant throughout the trading day. These quantitative findings are characteristic of the highly statistical nature of many-body, strongly interacting systems, typified by daily trading. It is therefore proposed that the values of these ratios, determined in the first hour-or-so of trading, be used to provide valuable information concerning the likely performance of the fine and intermediate components of the index for the remainder of the trading day.

A TEM Investigation of the Fine-Grained Matrix of the Martian Basaltic Breccia NWA 7034

NASA Technical Reports Server (NTRS)

Muttik, N.; Keller, L. P.; Agee, C. B.; McCubbin, F. M.; Santos, A. R.; Rahman, Z.

2014-01-01

The martian basaltic breccia NWA 7034 is characterized by fine-grained groundmass containing several different types of mineral grains and lithologic clasts. The matrix composition closely resembles Martian crustal rock and soil composition measured by recent rover and orbiter missions. The first results of NWA 7034 suggest that the brecciation of this martian meteorite may have formed due to eruptive volcanic processes; however, impact related brecciation processes have been proposed for paired meteorites NWA 7533 and NWA 7475]. Due to the very fine grain size of matrix, its textural details are difficult to resolve by optical and microprobe observations. In order to examine the potential nature of brecciation, transmission electron microscopy (TEM) studies combined with focused ion-beam technique (FIB) has been undertaken. Here we present the preliminary observations of fine-grained groundmass of NWA 7034 from different matrix areas by describing its textural and mineralogical variations and micro-structural characteristics.

Relative resolution: A hybrid formalism for fluid mixtures.

PubMed

Chaimovich, Aviel; Peter, Christine; Kremer, Kurt

2015-12-28

We show here that molecular resolution is inherently hybrid in terms of relative separation. While nearest neighbors are characterized by a fine-grained (geometrically detailed) model, other neighbors are characterized by a coarse-grained (isotropically simplified) model. We notably present an analytical expression for relating the two models via energy conservation. This hybrid framework is correspondingly capable of retrieving the structural and thermal behavior of various multi-component and multi-phase fluids across state space.

Relative resolution: A hybrid formalism for fluid mixtures

NASA Astrophysics Data System (ADS)

Chaimovich, Aviel; Peter, Christine; Kremer, Kurt

2015-12-01

We show here that molecular resolution is inherently hybrid in terms of relative separation. While nearest neighbors are characterized by a fine-grained (geometrically detailed) model, other neighbors are characterized by a coarse-grained (isotropically simplified) model. We notably present an analytical expression for relating the two models via energy conservation. This hybrid framework is correspondingly capable of retrieving the structural and thermal behavior of various multi-component and multi-phase fluids across state space.

Carbon and nitrogen cycling in southwestern ponderosa fine forests

Treesearch

Stephen C. Hart; Paul C. Selmants; Sarah I. Boyle; Steven T. Overby

2007-01-01

Ponderosa pine forests of the southwestern United States were historically characterized by relatively open, parklike stands with a bunchgrass-dominated understory. This forest structure was maintained by frequent, low-intensity surface fires. Heavy livestock grazing, fire suppression, and favorable weather conditions following Euro-American settlement in the late 19th...

Keratin sponge/hydrogel part 1. fabrication and characterization

USDA-ARS?s Scientific Manuscript database

Keratin sponge/hydrogel products formed by either the oxidation or reduction of U.S. domestic fine- or coarse-grade wool exhibited distinctively different topologies and molecular weights of 6- 8 kDa and 40-60 kDa, each with unique macro-porous structure and microstructural behaviors. The sponge/ ...

Neural network approach for characterizing structural transformations by X-ray absorption fine structure

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

Timoshenko, Janis; Frenkel, Anatoly I.; Cintins, Arturs

The knowledge of coordination environment around various atomic species in many functional materials provides a key for explaining their properties and working mechanisms. Many structural motifs and their transformations are difficult to detect and quantify in the process of work (operando conditions), due to their local nature, small changes, low dimensionality of the material, and/or extreme conditions. Here we use artificial neural network approach to extract the information on the local structure and its in-situ changes directly from the X-ray absorption fine structure spectra. We illustrate this capability by extracting the radial distribution function (RDF) of atoms in ferritic andmore » austenitic phases of bulk iron across the temperature-induced transition. Integration of RDFs allows us to quantify the changes in the iron coordination and material density, and to observe the transition from body-centered to face-centered cubic arrangement of iron atoms. Furthermore, this method is attractive for a broad range of materials and experimental conditions« less

Neural network approach for characterizing structural transformations by X-ray absorption fine structure

DOE PAGES

Timoshenko, Janis; Frenkel, Anatoly I.; Cintins, Arturs; ...

2018-05-25

The knowledge of coordination environment around various atomic species in many functional materials provides a key for explaining their properties and working mechanisms. Many structural motifs and their transformations are difficult to detect and quantify in the process of work (operando conditions), due to their local nature, small changes, low dimensionality of the material, and/or extreme conditions. Here we use artificial neural network approach to extract the information on the local structure and its in-situ changes directly from the X-ray absorption fine structure spectra. We illustrate this capability by extracting the radial distribution function (RDF) of atoms in ferritic andmore » austenitic phases of bulk iron across the temperature-induced transition. Integration of RDFs allows us to quantify the changes in the iron coordination and material density, and to observe the transition from body-centered to face-centered cubic arrangement of iron atoms. Furthermore, this method is attractive for a broad range of materials and experimental conditions« less

Neural Network Approach for Characterizing Structural Transformations by X-Ray Absorption Fine Structure Spectroscopy

NASA Astrophysics Data System (ADS)

Timoshenko, Janis; Anspoks, Andris; Cintins, Arturs; Kuzmin, Alexei; Purans, Juris; Frenkel, Anatoly I.

2018-06-01

The knowledge of the coordination environment around various atomic species in many functional materials provides a key for explaining their properties and working mechanisms. Many structural motifs and their transformations are difficult to detect and quantify in the process of work (operando conditions), due to their local nature, small changes, low dimensionality of the material, and/or extreme conditions. Here we use an artificial neural network approach to extract the information on the local structure and its in situ changes directly from the x-ray absorption fine structure spectra. We illustrate this capability by extracting the radial distribution function (RDF) of atoms in ferritic and austenitic phases of bulk iron across the temperature-induced transition. Integration of RDFs allows us to quantify the changes in the iron coordination and material density, and to observe the transition from a body-centered to a face-centered cubic arrangement of iron atoms. This method is attractive for a broad range of materials and experimental conditions.

Some Cenozoic hydrocarbon basins on the continental shelf of Vietnam

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

Dien, P.T.

1994-07-01

The formation of the East Vietnam Sea basins was related to different geodynamic processes. The pre-Oligocene basement consists of igneous, metamorphic, and metasediment complexes. The Cretaceous-Eocene basement formations are formed by convergence of continents after destruction of the Tethys Ocean. Many Jurassic-Eocene fractured magmatic highs of the Cuulong basin basement constitute important reservoirs that are producing good crude oil. The Paleocene-Eocene formations are characterized by intramountain metamolasses, sometimes interbedded volcanic rocks. Interior structures of the Tertiary basins connect with rifted branches of the widened East Vietnam Sea. Bacbo (Song Hong) basin is predominated by alluvial-rhythmic clastics in high-constructive deltas, whichmore » developed on the rifting and sagging structures of the continental branch. Petroleum plays are constituted from Type III source rocks, clastic reservoirs, and local caprocks. Cuulong basin represents sagging structures and is predominated by fine clastics, with tidal-lagoonal fine sandstone and shalestone in high-destructive deltas that are rich in Type II source rocks. The association of the pre-Cenozoic fractured basement reservoirs and the Oligocene-Miocene clastic reservoir sequences with the Oligocene source rocks and the good caprocks is frequently met in petroleum plays of this basin. Nan Conson basin was formed from complicated structures that are related to spreading of the oceanic branch. This basin is characterized by Oligocene epicontinental fine clastics and Miocene marine carbonates that are rich in Types I, II, and III organic matter. There are both pre-Cenozoic fractured basement reservoirs, Miocene buildup carbonate reservoir rocks and Oligocene-Miocene clastic reservoir sequences, in this basin. Pliocene-Quaternary sediments are sand and mud carbonates in the shelf facies of the East Vietnam Sea back-arc basin. Their great thickness provides good conditions for maturation and trapping.« less

Transition from two-dimensional photonic crystals to dielectric metasurfaces in the optical diffraction with a fine structure

PubMed Central

Rybin, Mikhail V.; Samusev, Kirill B.; Lukashenko, Stanislav Yu.; Kivshar, Yuri S.; Limonov, Mikhail F.

2016-01-01

We study experimentally a fine structure of the optical Laue diffraction from two-dimensional periodic photonic lattices. The periodic photonic lattices with the C4v square symmetry, orthogonal C2v symmetry, and hexagonal C6v symmetry are composed of submicron dielectric elements fabricated by the direct laser writing technique. We observe surprisingly strong optical diffraction from a finite number of elements that provides an excellent tool to determine not only the symmetry but also exact number of particles in the finite-length structure and the sample shape. Using different samples with orthogonal C2v symmetry and varying the lattice spacing, we observe experimentally a transition between the regime of multi-order diffraction, being typical for photonic crystals to the regime where only the zero-order diffraction can be observed, being is a clear fingerprint of dielectric metasurfaces characterized by effective parameters. PMID:27491952

Dopant activation mechanism of Bi wire-δ-doping into Si crystal, investigated with wavelength dispersive fluorescence x-ray absorption fine structure and density functional theory.

PubMed

Murata, Koichi; Kirkham, Christopher; Shimomura, Masaru; Nitta, Kiyofumi; Uruga, Tomoya; Terada, Yasuko; Nittoh, Koh-Ichi; Bowler, David R; Miki, Kazushi

2017-04-20

We successfully characterized the local structures of Bi atoms in a wire-δ-doped layer (1/8 ML) in a Si crystal, using wavelength dispersive fluorescence x-ray absorption fine structure at the beamline BL37XU, in SPring-8, with the help of density functional theory calculations. It was found that the burial of Bi nanolines on the Si(0 0 1) surface, via growth of Si capping layer at 400 °C by molecular beam epitaxy, reduced the Bi-Si bond length from [Formula: see text] to [Formula: see text] Å. We infer that following epitaxial growth the Bi-Bi dimers of the nanoline are broken, and the Bi atoms are located at substitutional sites within the Si crystal, leading to the shorter Bi-Si bond lengths.

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

Wang, Yiyu; Kannan, Rangasayee; Li, Leijun, E-mail

Non-equilibrium microstructure of the heat-affected zone (HAZ) in the as-welded modified 9Cr–1Mo–V–Nb pipe steel (P91) weldment deposited by gas tungsten arc welding (GTAW) and flux core arc welding (FCAW) has been characterized by field-emission scanning electron microscope (FESEM) and electron backscatter diffraction (EBSD). The heterogeneous structures in the sub-layers of the as-welded HAZ are attributable to phase transformations caused by the welding thermal cycles and the local structure variations in the as-received base metal. Coarse-grained heat-affected zone (CGHAZ) has a prior austenite grain (PAG) size of 20 μm. Fine uniformly-distributed precipitates and a higher fraction of MX carbonitrides are observedmore » in the CGHAZ. Fine-grained heat-affected zone (FGHAZ) consists of the finest grains (1.22 μm measured by EBSD, 5 μm PAG size), coarse undissolved M{sub 23}C{sub 6} carbides within the PAG boundaries and fine nucleated M{sub 23}C{sub 6} particles within the martensite laths. Inter-critical heat-affected zone (ICHAZ) consists of partially austenitized grains and over-tempered martensite laths. EBSD kernel average misorientation (KAM) map in the FGHAZ close to the ICHAZ illustrates the greatest local strain variations with a moderate normalized KAM value of 0.92°. The majority (88.1%) of the matrix grains in the CGHAZ are classified as deformed grains by EBSD grain average misorientation (GAM) evaluation. The FGHAZ close to the ICHAZ has the most recrystallized grains with an area fraction of 14.4%. The highest density variation of precipitates within grains in the FGHAZ originates from the inhomogeneous chemistry in the base metal. - Highlights: •A comprehensive characterization of the as-welded HAZ of P91 weldment is conducted. •Structural features in the each layer of the HAZ are quantified by EBSD. •Structural heterogenities in HAZ are due to welding cycle and base metal structure. •FGHAZ contains the finest grain structure and largest precipitate density variation.« less

Recent Advances in the Synthesis, Characterization and Application of Zn+‐containing Heterogeneous Catalysts

PubMed Central

Chen, Guangbo; Zhao, Yufei; Shang, Lu; Waterhouse, Geoffrey I. N.; Kang, Xiaofeng; Wu, Li‐Zhu; Tung, Chen‐Ho

2016-01-01

Monovalent Zn+ (3d104s1) systems possess a special electronic structure that can be exploited in heterogeneous catalysis and photocatalysis, though it remains challenge to synthesize Zn+‐containing materials. By careful design, Zn+‐related species can be synthesized in zeolite and layered double hydroxide systems, which in turn exhibit excellent catalytic potential in methane, CO and CO2 activation. Furthermore, by utilizing advanced characterization tools, including electron spin resonance, X‐ray absorption fine structure and density functional theory calculations, the formation mechanism of the Zn+ species and their structure‐performance relationships can be understood. Such advanced characterization tools guide the rational design of high‐performance Zn+‐containing catalysts for efficient energy conversion. PMID:27818902

Some issues for blast from a structural reactive material solid

NASA Astrophysics Data System (ADS)

Zhang, F.

2018-07-01

Structural reactive material (SRM) is consolidated from a mixture of micro- or nanometric reactive metals and metal compounds to the mixture theoretical maximum density. An SRM can thus possess a higher energy density, relying on various exothermic reactions, and higher mechanical strength and heat resistance than that of conventional CHNO explosives. Progress in SRM solid studies is reviewed specifically as an energy source for air blast through the reaction of fine SRM fragments under explosive loading. This includes a baseline SRM solid explosion characterization, material properties of an SRM solid, and its dynamic fine fragmentation mechanisms and fragment reaction mechanisms. The overview is portrayed mainly from the author's own experimental studies combined with theoretical and numerical explanation. These advances have laid down some fundamentals for the next stage of developments.

Telecom wavelength single quantum dots with very small excitonic fine-structure splitting

NASA Astrophysics Data System (ADS)

Kors, Andrei; Reithmaier, Johann Peter; Benyoucef, Mohamed

2018-04-01

We report on molecular beam epitaxy growth of symmetric InAs/InP quantum dots (QDs) emitting at a telecom C-band (1.55 μm) with an ultra-small excitonic fine-structure splitting of ˜2 μeV. The QDs are grown on a distributed Bragg reflector (DBR) and systematically characterized by micro-photoluminescence (μ-PL) measurements. One order of magnitude of QD PL intensity enhancement is observed in comparison to the samples without DBR. A combination of power-dependent and polarization-resolved measurements reveals background-free exciton, biexciton, and dark exciton emission with a resolution-limited linewidth below 35 μeV and a biexciton binding energy of ˜1 meV. The results are confirmed by statistical measurements of about 20 QDs.

Absence of bundle structure in the neocortex of the reeler mouse at the embryonic stage. Studies by scanning electron microscopic fractography.

PubMed

Mikoshiba, K; Nishimura, Y; Tsukada, Y

The reeler mutant mouse is characterized by a derangement of the cerebral cortical structure due to abnormalities during the migration step at the embryonic stage. We have analyzed both the control and reeler cerebral cortex by means of scanning electron microscopic fractography. In the control cerebral cortex, the bundle formation was composed of fine fibers on which the migrating neuroblasts were attached perpendicular to the pial surface, whereas no bundle formation was observed in the reeler; instead, there was a fine meshwork of fibers surrounding the neuroblasts. The possible role of bundle formation in the normal cerebral cortex and the correlation between the inability of cells to migrate and the absence of bundle formation in the reeler is discussed.

Some issues for blast from a structural reactive material solid

NASA Astrophysics Data System (ADS)

Zhang, F.

2018-03-01

Structural reactive material (SRM) is consolidated from a mixture of micro- or nanometric reactive metals and metal compounds to the mixture theoretical maximum density. An SRM can thus possess a higher energy density, relying on various exothermic reactions, and higher mechanical strength and heat resistance than that of conventional CHNO explosives. Progress in SRM solid studies is reviewed specifically as an energy source for air blast through the reaction of fine SRM fragments under explosive loading. This includes a baseline SRM solid explosion characterization, material properties of an SRM solid, and its dynamic fine fragmentation mechanisms and fragment reaction mechanisms. The overview is portrayed mainly from the author's own experimental studies combined with theoretical and numerical explanation. These advances have laid down some fundamentals for the next stage of developments.

Reactor for tracking catalyst nanoparticles in liquid at high temperature under a high-pressure gas phase with X-ray absorption spectroscopy.

PubMed

Nguyen, Luan; Tao, Franklin Feng

2018-02-01

Structure of catalyst nanoparticles dispersed in liquid phase at high temperature under gas phase of reactant(s) at higher pressure (≥5 bars) is important for fundamental understanding of catalytic reactions performed on these catalyst nanoparticles. Most structural characterizations of a catalyst performing catalysis in liquid at high temperature under gas phase at high pressure were performed in an ex situ condition in terms of characterizations before or after catalysis since, from technical point of view, access to the catalyst nanoparticles during catalysis in liquid phase at high temperature under high pressure reactant gas is challenging. Here we designed a reactor which allows us to perform structural characterization using X-ray absorption spectroscopy including X-ray absorption near edge structure spectroscopy and extended X-ray absorption fine structure spectroscopy to study catalyst nanoparticles under harsh catalysis conditions in terms of liquid up to 350 °C under gas phase with a pressure up to 50 bars. This reactor remains nanoparticles of a catalyst homogeneously dispersed in liquid during catalysis and X-ray absorption spectroscopy characterization.

Genomic structural differences between cattle and river buffalo identified through a combination and genomic and transcriptomic analysis

USDA-ARS?s Scientific Manuscript database

Water buffalo (Bubalus bubalis L.) is an important livestock species worldwide. Like many other livestock species, water buffalo lacks high quality and continuous reference genome assembly required for fine-scale comparative genomics studies. In this work, we present a dataset, which characterizes g...

Fine-scale population structure and the era of next-generation sequencing.

PubMed

Henn, Brenna M; Gravel, Simon; Moreno-Estrada, Andres; Acevedo-Acevedo, Suehelay; Bustamante, Carlos D

2010-10-15

Fine-scale population structure characterizes most continents and is especially pronounced in non-cosmopolitan populations. Roughly half of the world's population remains non-cosmopolitan and even populations within cities often assort along ethnic and linguistic categories. Barriers to random mating can be ecologically extreme, such as the Sahara Desert, or cultural, such as the Indian caste system. In either case, subpopulations accumulate genetic differences if the barrier is maintained over multiple generations. Genome-wide polymorphism data, initially with only a few hundred autosomal microsatellites, have clearly established differences in allele frequency not only among continental regions, but also within continents and within countries. We review recent evidence from the analysis of genome-wide polymorphism data for genetic boundaries delineating human population structure and the main demographic and genomic processes shaping variation, and discuss the implications of population structure for the distribution and discovery of disease-causing genetic variants, in the light of the imminent availability of sequencing data for a multitude of diverse human genomes.

Development of fine-resolution analyses and expanded large-scale forcing properties. Part I: Methodology and evaluation

DOE PAGES

Li, Zhijin; Vogelmann, Andrew M.; Feng, Sha; ...

2015-01-20

We produce fine-resolution, three-dimensional fields of meteorological and other variables for the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Southern Great Plains site. The Community Gridpoint Statistical Interpolation system is implemented in a multiscale data assimilation (MS-DA) framework that is used within the Weather Research and Forecasting model at a cloud-resolving resolution of 2 km. The MS-DA algorithm uses existing reanalysis products and constrains fine-scale atmospheric properties by assimilating high-resolution observations. A set of experiments show that the data assimilation analysis realistically reproduces the intensity, structure, and time evolution of clouds and precipitation associated with a mesoscale convective system.more » Evaluations also show that the large-scale forcing derived from the fine-resolution analysis has an overall accuracy comparable to the existing ARM operational product. For enhanced applications, the fine-resolution fields are used to characterize the contribution of subgrid variability to the large-scale forcing and to derive hydrometeor forcing, which are presented in companion papers.« less

Accurate mode characterization of two-mode optical fibers by in-fiber acousto-optics.

PubMed

Alcusa-Sáez, E; Díez, A; Andrés, M V

2016-03-07

Acousto-optic interaction in optical fibers is exploited for the accurate and broadband characterization of two-mode optical fibers. Coupling between LP 01 and LP 1m modes is produced in a broadband wavelength range. Difference in effective indices, group indices, and chromatic dispersions between the guided modes, are obtained from experimental measurements. Additionally, we show that the technique is suitable to investigate the fine modes structure of LP modes, and some other intriguing features related with modes' cut-off.

Acoustic fine structure may encode biologically relevant information for zebra finches.

PubMed

Prior, Nora H; Smith, Edward; Lawson, Shelby; Ball, Gregory F; Dooling, Robert J

2018-04-18

The ability to discriminate changes in the fine structure of complex sounds is well developed in birds. However, the precise limit of this discrimination ability and how it is used in the context of natural communication remains unclear. Here we describe natural variability in acoustic fine structure of male and female zebra finch calls. Results from psychoacoustic experiments demonstrate that zebra finches are able to discriminate extremely small differences in fine structure, which are on the order of the variation in acoustic fine structure that is present in their vocal signals. Results from signal analysis methods also suggest that acoustic fine structure may carry information that distinguishes between biologically relevant categories including sex, call type and individual identity. Combined, our results are consistent with the hypothesis that zebra finches can encode biologically relevant information within the fine structure of their calls. This study provides a foundation for our understanding of how acoustic fine structure may be involved in animal communication.

Polymorphic transition of solid-fats dispersed systems — its characterization by a novel method and scanning electron microscopy observation

NASA Astrophysics Data System (ADS)

Hirokawa, Norio; Ueda, Masahiro; Harano, Yoshio

1994-08-01

Solid-fats dispersed systems, such as margarine, butter and cacao-butter, were characterized by a novel method based on liquid permeation under pressure, for the simultaneous measurement of a solid-content ɛ p and an average diameter dp of solid particles (fats crystals) in them. Further, micro-structures of these systems were observed by a scanning electron microscope (SEM). As the result, it has been clarified that the spherical fats crystals of several μm in size appeared in the initial solid-fats products are agglomerates of fine particles of ca. 0.1 μm and that these fine particles are uniformly redispersed during an annealing treatment accompanying the reduction of ɛ p and dp. It is strongly suggested that this phenomenon is caused by a transition of fat crystals into a more stable polymorph.

Fabrication, characterization and fracture study of a machinable hydroxyapatite ceramic.

PubMed

Shareef, M Y; Messer, P F; van Noort, R

1993-01-01

In this study the preparation of a machinable hydroxyapatite from mixtures of a fine, submicrometer powder and either a coarse powder composed of porous aggregates up to 50 microns or a medium powder composed of dense particles of 3 microns median size is described. These were characterized using X-ray diffraction, transmission and scanning electron microscopy and infra-red spectroscopy. Test-pieces were formed by powder pressing and slip casting mixtures of various combinations of the fine, medium and coarse powders. The fired test-pieces were subjected to measurements of firing shrinkage, porosity, bulk density, tensile strength and fracture toughness. The microstructure and composition were examined using scanning electron microscopy and X-ray diffraction. For both processing methods, a uniform interconnected microporous structure was produced of a high-purity hydroxyapatite. The maximum tensile strength and fracture toughness that could be attained while retaining machinability were 37 MPa and 0.8 MPa m1/2 respectively.

Evaluation of multiple-scale 3D characterization for coal physical structure with DCM method and synchrotron X-ray CT.

PubMed

Wang, Haipeng; Yang, Yushuang; Yang, Jianli; Nie, Yihang; Jia, Jing; Wang, Yudan

2015-01-01

Multiscale nondestructive characterization of coal microscopic physical structure can provide important information for coal conversion and coal-bed methane extraction. In this study, the physical structure of a coal sample was investigated by synchrotron-based multiple-energy X-ray CT at three beam energies and two different spatial resolutions. A data-constrained modeling (DCM) approach was used to quantitatively characterize the multiscale compositional distributions at the two resolutions. The volume fractions of each voxel for four different composition groups were obtained at the two resolutions. Between the two resolutions, the difference for DCM computed volume fractions of coal matrix and pores is less than 0.3%, and the difference for mineral composition groups is less than 0.17%. This demonstrates that the DCM approach can account for compositions beyond the X-ray CT imaging resolution with adequate accuracy. By using DCM, it is possible to characterize a relatively large coal sample at a relatively low spatial resolution with minimal loss of the effect due to subpixel fine length scale structures.

Fine-scale spatial genetic structure of common and declining bumble bees across an agricultural landscape.

PubMed

Dreier, Stephanie; Redhead, John W; Warren, Ian A; Bourke, Andrew F G; Heard, Matthew S; Jordan, William C; Sumner, Seirian; Wang, Jinliang; Carvell, Claire

2014-07-01

Land-use changes have threatened populations of many insect pollinators, including bumble bees. Patterns of dispersal and gene flow are key determinants of species' ability to respond to land-use change, but have been little investigated at a fine scale (<10 km) in bumble bees. Using microsatellite markers, we determined the fine-scale spatial genetic structure of populations of four common Bombus species (B. terrestris, B. lapidarius, B. pascuorum and B. hortorum) and one declining species (B. ruderatus) in an agricultural landscape in Southern England, UK. The study landscape contained sown flower patches representing agri-environment options for pollinators. We found that, as expected, the B. ruderatus population was characterized by relatively low heterozygosity, number of alleles and colony density. Across all species, inbreeding was absent or present but weak (FIS  = 0.01-0.02). Using queen genotypes reconstructed from worker sibships and colony locations estimated from the positions of workers within these sibships, we found that significant isolation by distance was absent in B. lapidarius, B. hortorum and B. ruderatus. In B. terrestris and B. pascuorum, it was present but weak; for example, in these two species, expected relatedness of queens founding colonies 1 m apart was 0.02. These results show that bumble bee populations exhibit low levels of spatial genetic structure at fine spatial scales, most likely because of ongoing gene flow via widespread queen dispersal. In addition, the results demonstrate the potential for agri-environment scheme conservation measures to facilitate fine-scale gene flow by creating a more even distribution of suitable habitats across landscapes. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Characterization of nanoscale oxide and oxyhydroxide powders using EXAFS spectroscopy

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

Darab, J.G.; Linehan, J.C.; Matson, D.W.

1993-06-01

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to determine the structural environment local to iron(HI) and zircorium(IV) cations in respectively, nanoscale iron oxyhydroxide and nanoscale zirconium oxide powders. The iron oxyhydroxide powder, produced by the modified reverse micelle (MRM) technology, was found to have a short-range structure most similar to that of goethite ([alpha]-FeOOH). The short-range structure of the zirconium oxide powder, produced using the rapid thermal decomposition of solutes (RTDS) technology, was found to be a mixture of monoclinic zirconia and cubic zirconia environments.

Characterization of nanoscale oxide and oxyhydroxide powders using EXAFS spectroscopy

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

Darab, J.G.; Linehan, J.C.; Matson, D.W.

1993-06-01

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to determine the structural environment local to iron(HI) and zircorium(IV) cations in respectively, nanoscale iron oxyhydroxide and nanoscale zirconium oxide powders. The iron oxyhydroxide powder, produced by the modified reverse micelle (MRM) technology, was found to have a short-range structure most similar to that of goethite ({alpha}-FeOOH). The short-range structure of the zirconium oxide powder, produced using the rapid thermal decomposition of solutes (RTDS) technology, was found to be a mixture of monoclinic zirconia and cubic zirconia environments.

T-RMSD: a fine-grained, structure-based classification method and its application to the functional characterization of TNF receptors.

PubMed

Magis, Cedrik; Stricher, François; van der Sloot, Almer M; Serrano, Luis; Notredame, Cedric

2010-07-16

This study addresses the relation between structural and functional similarity in proteins. We introduce a novel method named tree based on root mean square deviation (T-RMSD), which uses distance RMSD (dRMSD) variations to build fine-grained structure-based classifications of proteins. The main improvement of the T-RMSD over similar methods, such as Dali, is its capacity to produce the equivalent of a bootstrap value for each cluster node. We validated our approach on two domain families studied extensively for their role in many biological and pathological pathways: the small GTPase RAS superfamily and the cysteine-rich domains (CRDs) associated with the tumor necrosis factor receptors (TNFRs) family. Our analysis showed that T-RMSD is able to automatically recover and refine existing classifications. In the case of the small GTPase ARF subfamily, T-RMSD can distinguish GTP- from GDP-bound states, while in the case of CRDs it can identify two new subgroups associated with well defined functional features (ligand binding and formation of ligand pre-assembly complex). We show how hidden Markov models (HMMs) can be built on these new groups and propose a methodology to use these models simultaneously in order to do fine-grained functional genomic annotation without known 3D structures. T-RMSD, an open source freeware incorporated in the T-Coffee package, is available online. 2010 Elsevier Ltd. All rights reserved.

Relating binaural pitch perception to the individual listener's auditory profile.

PubMed

Santurette, Sébastien; Dau, Torsten

2012-04-01

The ability of eight normal-hearing listeners and fourteen listeners with sensorineural hearing loss to detect and identify pitch contours was measured for binaural-pitch stimuli and salience-matched monaurally detectable pitches. In an effort to determine whether impaired binaural pitch perception was linked to a specific deficit, the auditory profiles of the individual listeners were characterized using measures of loudness perception, cognitive ability, binaural processing, temporal fine structure processing, and frequency selectivity, in addition to common audiometric measures. Two of the listeners were found not to perceive binaural pitch at all, despite a clear detection of monaural pitch. While both binaural and monaural pitches were detectable by all other listeners, identification scores were significantly lower for binaural than for monaural pitch. A total absence of binaural pitch sensation coexisted with a loss of a binaural signal-detection advantage in noise, without implying reduced cognitive function. Auditory filter bandwidths did not correlate with the difference in pitch identification scores between binaural and monaural pitches. However, subjects with impaired binaural pitch perception showed deficits in temporal fine structure processing. Whether the observed deficits stemmed from peripheral or central mechanisms could not be resolved here, but the present findings may be useful for hearing loss characterization.

The dispersion of fine chitosan particles by beads-milling

NASA Astrophysics Data System (ADS)

Rochima, Emma; Utami, Safira; Hamdani, Herman; Azhary, Sundoro Yoga; Praseptiangga, Danar; Joni, I. Made; Panatarani, Camellia

2018-02-01

This research aimed to produce fine chitosan particles from a crab shell waste by beads-milling method by two different concentration of PEG as dispersing agent (150 and 300 wt. %). The characterization was performed to obtain the size and size distribution, the characteristics of functional groups and the degree of deacetylation. The results showed that the chitosan fine particles was obtained with a milling time 120 minutes with the best concentration of PEG 400 150 wt. %. The average particle size of the as-prepared suspension is 584 nm after addition of acetic acid solution (1%, v/v). Beads milling process did not change the glucosamine and N-acetylglucosamine content on chitosan structure which is indicated by degree of deacetylation higher than 70%. It was concluded that beads milling process can be applied to prepare chitosan fineparticles by proper adjustment in the milling time, pH and dosage of dispersing agent.

Enhanced Efficiency in Fullerene-Free Polymer Solar Cell by Incorporating Fine-designed Donor and Acceptor Materials.

PubMed

Ye, Long; Sun, Kai; Jiang, Wei; Zhang, Shaoqing; Zhao, Wenchao; Yao, Huifeng; Wang, Zhaohui; Hou, Jianhui

2015-05-06

Among the diverse nonfullerene acceptors, perylene bisimides (PBIs) have been attracting much attention due to their excellent electron mobility and tunable molecular and electronic properties by simply engineering the bay and head linkages. Herein, guided by two efficient small molecular acceptors, we designed, synthesized, and characterized a new nonfullerene small molecule PPDI with fine-tailored alkyl chains. Notably, a certificated PCE of 5.40% is realized in a simple structured fullerene-free polymer solar cell comprising PPDI as the electron acceptor and a fine-tailored 2D-conjugated polymer PBDT-TS1 as the electron donor. Moreover, the device behavior, morphological feature, and origin of high efficiency in PBDT-TS1/PPDI-based fullerene-free PSC were investigated. The synchronous selection and design of donor and acceptor materials reported here offer a feasible strategy for realizing highly efficient fullerene-free organic photovoltaics.

An ethanol-based fixation method for anatomical and micro-morphological characterization of leaves of various tree species.

PubMed

Chieco, C; Rotondi, A; Morrone, L; Rapparini, F; Baraldi, R

2013-02-01

The use of formalin constitutes serious health hazards for laboratory workers. We investigated the suitability and performance of the ethanol-based fixative, FineFIX, as a substitute for formalin for anatomical and cellular structure investigations of leaves by light microscopy and for leaf surface and ultrastructural analysis by scanning electron microscopy (SEM). We compared the anatomical features of leaf materials prepared using conventional formalin fixation with the FineFIX. Leaves were collected from ornamental tree species commonly used in urban areas. FineFIX was also compared with glutaraldehyde fixation and air drying normally used for scanning electron microscopy to develop a new method for evaluating leaf morphology and microstructure in three ornamental tree species. The cytological features of the samples processed for histological analysis were well preserved by both fixatives as demonstrated by the absence of nuclear swelling or shrinkage, cell wall detachment or tissue flaking, and good presentation of cytoplasmic vacuolization. In addition, good preservation of surface details and the absence of shrinkage artefacts confirmed the efficacy of FineFIX fixation for SEM analysis. Cuticular wax was preserved only in air dried samples. Samples treated with chemical substances during the fixation and dehydration phases showed various alterations of the wax structures. In some air dried samples a loss of turgidity of the cells was observed that caused general wrinkling of the epidermal surfaces. Commercial FineFIX is an adequate substitute for formalin in histology and it can be applied successfully also for SEM investigation, while reducing the health risks of glutaraldehyde or other toxic fixatives. To investigate the potential for plants to absorb and capture particulates in air, which requires preservation of the natural morphology of trichomes and epicuticular waxes, a combination of FineFIX fixation and air drying is recommended.

Synthesis and characterization of a novel porous titanium silicate/g-C{sub 3}N{sub 4} hybrid nanocomposite catalyst for environmental applications

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

Adepu, Ajay Kumar; Narayanan, Venkatathri, E-mail: venkatathrin@yahoo.com, E-mail: ajay.kumar553@gmail.com

2016-04-13

Herein we developed a novel porous Titanium silicate/g-C{sub 3}N{sub 4} (TSCN) hybrid composite with a inorganic-organic heterojunction. The synthesized porous TSCN were well characterized by various analytical techniques for structural and chemical properties evaluation. FESEM results shows the growth of finely distributed porous titanium silicate on the surface of the g-C{sub 3}N{sub 4}. Porous TSCN hybrid nanocomposite has a great influence on the electronic and optical properties.

Imaging spectroscopy of solar radio burst fine structures.

PubMed

Kontar, E P; Yu, S; Kuznetsov, A A; Emslie, A G; Alcock, B; Jeffrey, N L S; Melnik, V N; Bian, N H; Subramanian, P

2017-11-15

Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the Low Frequency Array, an instrument with high-time resolution that also permits imaging at scales much shorter than those corresponding to radio wave propagation in the corona. The observations demonstrate that radio wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.

The effective fine-structure constant of freestanding graphene measured in graphite.

PubMed

Reed, James P; Uchoa, Bruno; Joe, Young Il; Gan, Yu; Casa, Diego; Fradkin, Eduardo; Abbamonte, Peter

2010-11-05

Electrons in graphene behave like Dirac fermions, permitting phenomena from high-energy physics to be studied in a solid-state setting. A key question is whether or not these fermions are critically influenced by Coulomb correlations. We performed inelastic x-ray scattering experiments on crystals of graphite and applied reconstruction algorithms to image the dynamical screening of charge in a freestanding graphene sheet. We found that the polarizability of the Dirac fermions is amplified by excitonic effects, improving screening of interactions between quasiparticles. The strength of interactions is characterized by a scale-dependent, effective fine-structure constant, α(g)* (k,ω), the value of which approaches 0.14 ± 0.092 ~ 1/7 at low energy and large distances. This value is substantially smaller than the nominal α(g) = 2.2, suggesting that, on the whole, graphene is more weakly interacting than previously believed.

Probing Sub-atomistic Free-Volume Imperfections in Dry-Milled Nanoarsenicals with PAL Spectroscopy.

PubMed

Shpotyuk, Oleh; Ingram, Adam; Bujňáková, Zdenka; Baláž, Peter; Shpotyuk, Yaroslav

2016-12-01

Structural transformations caused by coarse-grained powdering and fine-grained mechanochemical milling in a dry mode were probed in high-temperature modification of tetra-arsenic tetra-sulfide known as β-As4S4. In respect to X-ray diffraction analysis, the characteristic sizes of β-As4S4 crystallites in these coarse- and fine-grained powdered pellets were 90 and 40 nm, respectively. Positron annihilation lifetime spectroscopy was employed to characterize transformations occurred in free-volume structure of these nanoarsenicals. Experimentally measured positron lifetime spectra were parameterized in respect to three- or two-term fitting procedures and respectively compared with those accumulated for single crystalline realgar α-As4S4 polymorph. The effect of coarse-grained powdering was found to result in generation of large amount of positron and positronium Ps trapping sites inside arsenicals in addition to existing ones. In fine-grained powdered β-As4S4 pellets, the positron trapping sites with characteristic free volumes close to bi- and tri-atomic vacancies were evidently dominated. These defects were supposed to originate from grain boundary regions and interfacial free volumes near aggregated β-As4S4 crystallites. Thus, the cumulative production of different positron traps with lifetimes close to defect-related lifetimes in realgar α-As4S4 polymorph was detected in fine-grained milled samples.

Characterization of local atomic structure in Co/Zn based ZIFs by XAFS

NASA Astrophysics Data System (ADS)

Podkovyrina, Yulia; Butova, Vera; Bulanova, Elena; Budnyk, Andriy; Kremennaya, Maria; Soldatov, Alexander; Lamberti, Carlo

2018-03-01

The local atomic structure in bimetallic Co/Zn zeolitic imidazolate frameworks (ZIFs) was studied using X-ray Absorption Fine Structure (XAFS) spectroscopy and theoretical calculations. The experimental Co K-edge and Zn K-edge XANES (X-ray Absorption Near Edge Structure) spectra of Zn1-xCoxC8H10N4 samples (x = 0.05, 0.25, 0.75) synthesized by microwave synthesis were compared with the data for the ZIF-67 (x=1) and ZIF-8 (x=0). Theoretical XANES spectra for the bimetallic ZIFs were calculated. It was shown that in bimetallic ZIFs the Co and Zn atoms have the similar local environment.

Novel arabinan and galactan oligosaccharides from dicotyledonous plants

NASA Astrophysics Data System (ADS)

Wefers, Daniel; Tyl, Catrin; Bunzel, Mirko

2014-11-01

Arabinans and galactans are neutral pectic side chains and an important part of the cell walls of dicotyledonous plants. To get a detailed insight into their fine structure, various oligosaccharides were isolated from quinoa, potato galactan, and sugar beet pulp after enzymatic treatment. LC-MS2 and one- and two-dimensional NMR spectroscopy were used for unambiguous structural characterization. It was demonstrated that arabinans contain β-(1→3)-linked arabinobiose as a side chain in quinoa seeds, while potato galactan was comprised of β-(1→4)-linked galactopyranoses which are interspersed with α-(1→4)-linked arabinopyranoses. Additionally, an oligosaccharide with two adjacent arabinofuranose units O2-substituted with two ferulic acid monomers was characterized. The isolated oligosaccharides gave further insight into the structures of pectic side chains and may have an impact on plant physiology and dietary fiber fermentation.

The role of yttrium and titanium during the development of ODS ferritic steels obtained through the STARS route: TEM and XAS study

NASA Astrophysics Data System (ADS)

Ordás, Nerea; Gil, Emma; Cintins, Arturs; de Castro, Vanessa; Leguey, Teresa; Iturriza, Iñigo; Purans, Juris; Anspoks, Andris; Kuzmin, Alexei; Kalinko, Alexandr

2018-06-01

Oxide Dispersion Strengthened Ferritic Steels (ODS FS) are candidate materials for structural components in future fusion reactors. Their high strength and creep resistance at elevated temperatures and their good resistance to neutron radiation damage is obtained through extremely fine microstructures containing a high density of nanometric precipitates, generally yttrium and titanium oxides. This work shows transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) characterization of Fe-14Cr-2W-0.3Ti-0.24Y ODS FS obtained by the STARS route (Surface Treatment of gas Atomized powder followed by Reactive Synthesis), an alternative method to obtain ODS alloys that avoids the mechanical alloying to introduce Y2O3 powder particles. In this route, FS powders already containing Ti and Y, precursors of the nanometric oxides, are obtained by gas atomization. Then, a metastable Cr- and Fe-rich oxide layer is formed on the surface of the powder particles. During consolidation by HIP at elevated temperatures, and post-HIP heat treatments above the HIP temperature, this oxide layer at Prior Particle Boundaries (PPBs) dissociates, the oxygen diffuses, and Y-Ti-O nano-oxides precipitate in the ferritic matrix. TEM characterization combined with XAFS and XANES analyses have proven to be suitable tools to follow the evolution of the nature of the different oxides present in the material during the whole processing route and select appropriate HIP and post-HIP parameters to promote profuse and fine Y-Ti-O nanometric precipitates.

M553 sphere forming experiment: Pure nickel specimen evaluation

NASA Technical Reports Server (NTRS)

Johnson, P. C.; Peters, E. T.

1973-01-01

A region or cap of very fine two-dimensional surface growth structure was observed at the top of three of the six pure nickel flight specimens. Such two-dimensional surface growth structures have been observed both on the ground-based specimens and on other surface areas of the flight specimens. However, the fine structures observed on the three flight samples are at least an order of magnitude finer than those previously observed, and resemble similar localized, fine, two-dimensional surface structures observed in both ground and flight specimens for the nickel alloys. The two-dimensional growth areas consist primarily of fine equiaxed grains, specimen SL-2.6, fine dendrites, specimen SL-2.5, or a core of fine equiaxed grains surrounded by a ring of fine dendrites, specimen SL-1.9.

Cations Form Sequence Selective Motifs within DNA Grooves via a Combination of Cation-Pi and Ion-Dipole/Hydrogen Bond Interactions

PubMed Central

Stewart, Mikaela; Dunlap, Tori; Dourlain, Elizabeth; Grant, Bryce; McFail-Isom, Lori

2013-01-01

The fine conformational subtleties of DNA structure modulate many fundamental cellular processes including gene activation/repression, cellular division, and DNA repair. Most of these cellular processes rely on the conformational heterogeneity of specific DNA sequences. Factors including those structural characteristics inherent in the particular base sequence as well as those induced through interaction with solvent components combine to produce fine DNA structural variation including helical flexibility and conformation. Cation-pi interactions between solvent cations or their first hydration shell waters and the faces of DNA bases form sequence selectively and contribute to DNA structural heterogeneity. In this paper, we detect and characterize the binding patterns found in cation-pi interactions between solvent cations and DNA bases in a set of high resolution x-ray crystal structures. Specifically, we found that monovalent cations (Tl+) and the polarized first hydration shell waters of divalent cations (Mg2+, Ca2+) form cation-pi interactions with DNA bases stabilizing unstacked conformations. When these cation-pi interactions are combined with electrostatic interactions a pattern of specific binding motifs is formed within the grooves. PMID:23940752

Cations form sequence selective motifs within DNA grooves via a combination of cation-pi and ion-dipole/hydrogen bond interactions.

PubMed

Stewart, Mikaela; Dunlap, Tori; Dourlain, Elizabeth; Grant, Bryce; McFail-Isom, Lori

2013-01-01

The fine conformational subtleties of DNA structure modulate many fundamental cellular processes including gene activation/repression, cellular division, and DNA repair. Most of these cellular processes rely on the conformational heterogeneity of specific DNA sequences. Factors including those structural characteristics inherent in the particular base sequence as well as those induced through interaction with solvent components combine to produce fine DNA structural variation including helical flexibility and conformation. Cation-pi interactions between solvent cations or their first hydration shell waters and the faces of DNA bases form sequence selectively and contribute to DNA structural heterogeneity. In this paper, we detect and characterize the binding patterns found in cation-pi interactions between solvent cations and DNA bases in a set of high resolution x-ray crystal structures. Specifically, we found that monovalent cations (Tl⁺) and the polarized first hydration shell waters of divalent cations (Mg²⁺, Ca²⁺) form cation-pi interactions with DNA bases stabilizing unstacked conformations. When these cation-pi interactions are combined with electrostatic interactions a pattern of specific binding motifs is formed within the grooves.

Development of a Linear Ion Trap Mass Spectrometer (LITMS) Investigation for Future Planetary Surface Missions

NASA Technical Reports Server (NTRS)

Brinckerhoff, W.; Danell, R.; Van Ameron, F.; Pinnick, V.; Li, X.; Arevalo, R.; Glavin, D.; Getty, S.; Mahaffy, P.; Chu, P.;

Flux Quantization in Aperiodic and Periodic Networks

NASA Astrophysics Data System (ADS)

Behrooz, Angelika

The normal - superconducting phase boundary, T_{c}(H), of a periodic wire network shows periodic oscillations with period H _{o} = phi_ {o}/A due to flux quantization around the individual plaquettes (of area A) of the network. The magnetic flux quantum is phi_{o } = hc/2e. The phase boundary also shows fine structure at fields H = (p/q)H_{o} (p,q integers), where the flux vortices can form commensurate superlattices on the periodic substrate. We have studied the phase boundary of quasicrystalline, quasiperiodic and random networks. We have found that if a network is composed of two different tiles, whose areas are relatively irrational then the T_ {c}(H) curve shows large scale structure at fields that approximate flux quantization around the tiles, i.e. when the ratio of fluxoids contained in the large tiles to those in the small tiles is a rational approximant to the irrational area ratio. The phase boundaries of quasicrystalline and quasiperiodic networks show fine structure indicating the existence of commensurate vortex superlattices on these networks. No such fine structure is found on the random array. For a quasicrystal whose quasiperiodic long-range order is characterized by the irrational number tau the commensurate vortex lattices are all found at H = H_{o}| n + mtau| (n,m integers). We have found that the commensurate superlattices on quasicrystalline as well as on crystalline networks are related to the inflation symmetry. We propose a general definition of commensurability.

Quantitative characterization of porosity in stainless steel LENS powders and deposits

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

Susan, D.F.; Puskar, J.D.; Brooks, J.A.

2006-07-15

Laser Engineered Net Shaping (LENS) utilizes a laser beam to melt fine powders to produce three-dimensional engineering structures line by line and layer by layer. When building these structures, defects including lack-of-fusion (LOF) at interlayer boundaries and intralayer porosity are sometimes observed. LOF defects can be minimized by adjusting processing parameters, but the sources of intralayer porosity are less apparent. In this paper, the amount and size distributions of 17-4PH and 304L powders and pores within the powder were characterized in parallel with the intralayer porosity in LENS deposits fabricated from the same materials. Intralayer porosity increased with increased powdermore » porosity; but was not well correlated with deposition parameters. The results demonstrate the importance of careful characterization and specification of starting powders on the quality of the final LENS deposits.« less

Solar Cycle Fine Structure and Surface Rotation from Ca II K-Line Time Series Data

NASA Astrophysics Data System (ADS)

Scargle, Jeff; Keil, Steve; Worden, Pete

2011-10-01

Analysis of three and a half decades of data from the NSO/AFRL/Sac Peak K-line monitoring program yields evidence for four components to the variation: (a) the solar cycle, with considerable fine structure and a quasi-periodicity of 122.4 days; (b) a stochastic process, faster than (a) and largely independent of it, (c) a quasi-periodic signal due to rotational modulation, and of course (d) observational errors (shown to be quite small). Correlation and power spectrum analyses elucidate periodic and aperiodic variation of these chromospheric parameters. Time-frequency analysis is especially useful for extracting information about differential rotation, and in particular elucidates the connection between its behavior and fine structure of the solar cycle on approximately one-year time scales. These results further suggest that similar analyses will be useful at detecting and characterizing differential rotation in stars from stellar light-curves such as those being produced by NASA's Kepler observatory. Component (b) consists of variations over a range of timescales, in the manner of a "1/f" random process. A time-dependent Wilson-Bappu effect appears to be present in the solar cycle variations (a), but not in the stochastic process (b). The data can be found at the National Solar Observatory web site http://nsosp.nso.edu/data/cak_mon.html, or by file transfer protocol at ftp://ftp.nso.edu/idl/cak.parameters.

Fine Specificity and Cross-Reactions of Monoclonal Antibodies to Group B Streptococcal Capsular Polysaccharide Type III

PubMed Central

Pincus, Seth H.; Moran, Emily; Maresh, Grace; Jennings, Harold J.; Pritchard, David G.; Egan, Marianne L.; Blixt, Ola

2012-01-01

Group B streptococcus (GBS) is a major cause of neonatal sepsis and meningitis. Despite aggressive campaigns using antenatal prophylactic antibiotic therapy, infections continue. Developing an effective maternal vaccine is a public health priority. Antibody (Ab) to the capsular polysaccharide (CPS) is considered the dominant “protective” immune mediator. Here we study the fine specificity and potential host reactivity of a panel of well-characterized murine monoclonal Abs against the type III CPS by examining the binding of the Abs to intact and neuraminidase-digested GBS, purified CPS, synthetic carbohydrate structures, and cells. The results showed marked differences in the fine specificity among these mAbs to a single carbohydrate structure. Cross-reactions with synthetic GD3 and GT3 carbohydrates, representing structures found on surfaces of neural and developing cells, were demonstrated using carbohydrate array technology. The anti-CPSIII mAbs did not react with cells expressing GD3 and GT3, nor did mAbs specific for the host carbohydrates cross-react with GBS, raising questions about the physiological relevance of this cross-reaction. But in the process of these investigations, we serendipitously demonstrated cross-reactions of some anti-CPSIII mAbs with antigens, likely carbohydrates, found on human leukocytes. These studies suggest caution in the development of a maternal vaccine to prevent infection by this important human pathogen. PMID:22634296

Fine specificity and cross-reactions of monoclonal antibodies to group B streptococcal capsular polysaccharide type III.

PubMed

Pincus, Seth H; Moran, Emily; Maresh, Grace; Jennings, Harold J; Pritchard, David G; Egan, Marianne L; Blixt, Ola

2012-07-06

Group B streptococcus (GBS) is a major cause of neonatal sepsis and meningitis. Despite aggressive campaigns using antenatal prophylactic antibiotic therapy, infections continue. Developing an effective maternal vaccine is a public health priority. Antibody (Ab) to the capsular polysaccharide (CPS) is considered the dominant "protective" immune mediator. Here we study the fine specificity and potential host reactivity of a panel of well-characterized murine monoclonal Abs against the type III CPS by examining the binding of the Abs to intact and neuraminidase-digested GBS, purified CPS, synthetic carbohydrate structures, and cells. The results showed marked differences in the fine specificity among these mAbs to a single carbohydrate structure. Cross-reactions with synthetic GD3 and GT3 carbohydrates, representing structures found on surfaces of neural and developing cells, were demonstrated using carbohydrate array technology. The anti-CPS(III) mAbs did not react with cells expressing GD3 and GT3, nor did mAbs specific for the host carbohydrates cross-react with GBS, raising questions about the physiological relevance of this cross-reaction. But in the process of these investigations, we serendipitously demonstrated cross-reactions of some anti-CPS(III) mAbs with antigens, likely carbohydrates, found on human leukocytes. These studies suggest caution in the development of a maternal vaccine to prevent infection by this important human pathogen. Copyright © 2012 Elsevier Ltd. All rights reserved.

Manufacturing an advanced process characterization reticle incorporating halftone biasing

NASA Astrophysics Data System (ADS)

Nakagawa, Kent H.; Van Den Broeke, Douglas J.; Chen, J. Fung; Laidig, Thomas L.; Wampler, Kurt E.; Caldwell, Roger F.

1999-04-01

As the semiconductor roadmap continues to require imaging of smaller feature son wafers, we continue to explore new approaches in OPC strategies to extend the lifespan of existing technology. In this paper, we study a new OPC technology, called halftone biasing, and its application on an OPC characterization reticle, designed by MicroUnity Systems Engineering, Inc. The RTP9 test reticle is the latest in a series of 'LineSweeper' characterization reticles. Each reticle contains a wide range of line width sand pitches, each with several alternative OPC treatments, including references cases, scattering bars, and fine biasing. One of RTP9's design requirements was to support very fine, incremental biases for densely-pitched lines. Ordinarily, this would dictate a reduced address unit and with it the costly penalty of a square-law increase in e- beam write time. RTP9 incorporates a new OPC strategy, called halftone biasing, which has been proposed to address this problem. Taking advantage of optical reduction printing, this technique applies a sub-resolution halftone screen to the edges of figures to accomplish fine biasing equivalent to using an address unit one-fourth of the size of the actual e-beam writing grid. The resulting edge structure has some of the characteristics of aggressive OPC structures, but can be used in areas where traditional scattering bars cannot be placed. The trade-off between the faster write times achieved and the inflation of pattern file size is examined. The manufacturability and inspectability of halftone-biased lines on the RTP9 test reticle are explored. Pattern fidelity is examined using both optical and SEM tools. Printed 0.18 micrometers DUV resist line edge profiles are compared for both halftone and non- halftone feature edges. The CD uniformity of the OPC features, and result of die-to-database inspection are reported. The application of halftone biasing to real circuits, including the impact of data volume and saved write time, is also discussed.

Molecular rheology of branched polymers: decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling.

PubMed

van Ruymbeke, E; Lee, H; Chang, T; Nikopoulou, A; Hadjichristidis, N; Snijkers, F; Vlassopoulos, D

2014-07-21

An emerging challenge in polymer physics is the quantitative understanding of the influence of a macromolecular architecture (i.e., branching) on the rheological response of entangled complex polymers. Recent investigations of the rheology of well-defined architecturally complex polymers have determined the composition in the molecular structure and identified the role of side-products in the measured samples. The combination of different characterization techniques, experimental and/or theoretical, represents the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use statistical tools in order to relate the information available from the synthesis protocols of a sample and its experimental molar mass distribution (typically obtained from size exclusion chromatography), and hence obtain precise information about its structural composition, i.e. enhance the existing sensitivity limit. We critically discuss the use of linear rheology as a reliable quantitative characterization tool, along with the recently developed temperature gradient interaction chromatography. The latter, which has emerged as an indispensable characterization tool for branched architectures, offers unprecedented sensitivity in detecting the presence of different molecular structures in a sample. Combining these techniques is imperative in order to quantify the molecular composition of a polymer and its consequences on the macroscopic properties. We validate this approach by means of a new model asymmetric comb polymer which was synthesized anionically. It was thoroughly characterized and its rheology was carefully analyzed. The main result is that the rheological signal reveals fine molecular details, which must be taken into account to fully elucidate the viscoelastic response of entangled branched polymers. It is important to appreciate that, even optimal model systems, i.e., those synthesized with high-vacuum anionic methods, need thorough characterization via a combination of techniques. Besides helping to improve synthetic techniques, this methodology will be significant in fine-tuning mesoscopic tube-based models and addressing outstanding issues such as the quantitative description of the constraint release mechanism.

Quantitative phase imaging of arthropods

PubMed Central

Sridharan, Shamira; Katz, Aron; Soto-Adames, Felipe; Popescu, Gabriel

2015-01-01

Abstract. Classification of arthropods is performed by characterization of fine features such as setae and cuticles. An unstained whole arthropod specimen mounted on a slide can be preserved for many decades, but is difficult to study since current methods require sample manipulation or tedious image processing. Spatial light interference microscopy (SLIM) is a quantitative phase imaging (QPI) technique that is an add-on module to a commercial phase contrast microscope. We use SLIM to image a whole organism springtail Ceratophysella denticulata mounted on a slide. This is the first time, to our knowledge, that an entire organism has been imaged using QPI. We also demonstrate the ability of SLIM to image fine structures in addition to providing quantitative data that cannot be obtained by traditional bright field microscopy. PMID:26334858

Application of x-ray absorption fine structure (XAFS) to local-order analysis in Fe-Cr maghemite-like materials

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

Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx; Fuentes-Cobas, L. E.; Macías-Ríos, E.

2015-07-23

The maghemite-like oxide system γ-Fe{sub 2-x}Cr{sub x}O{sub 3} (x=0.75, 1 and 1.25) was studied by X-ray absorption fine structure (XAFS) and by synchrotron radiation X-ray diffraction (XRD). Measurements were performed at the Stanford Synchrotron Radiation Lightsource at room temperature, at beamlines 2-1, 2-3 and 4-3. High-resolution XRD patterns were processed by means of the Rietveld method. In cases of atoms being neighbors in the Periodic Table, the order/disorder degree of the considered solutions is indiscernible by “normal” (absence of “anomalous scattering”) diffraction experiments. Thus, maghemite-like materials were investigated by XAFS in both Fe and Cr K-edges to clarify, via short-rangemore » structure characterization, the local ordering of the investigated system. Athena and Artemis graphic user interfaces for IFEFFIT and FEFF8.4 codes were employed for XAFS spectra interpretation. Pre-edge decomposition and theoretical modeling of X-ray absorption near edge structure (XANES) transitions were performed. By analysis of the Cr K-edge XANES, it has been confirmed that Cr is located in an octahedral environment. Fitting of the extended X-ray absorption fine structure (EXAFS) spectra was performed under the consideration that the central atom of Fe is allowed to occupy octa- and tetrahedral positions, while Cr occupies only octahedral ones. Coordination number of neighboring atoms, interatomic distances and their quadratic deviation average were determined for x=1, by fitting simultaneously the EXAFS spectra of both Fe and Cr K-edges. The results of fitting the experimental spectra with theoretical standards showed that the cation vacancies tend to follow a regular pattern within the structure of the iron-chromium maghemite (FeCrO{sub 3})« less

Fine structure of heliumlike ions and determination of the fine structure constant.

PubMed

Pachucki, Krzysztof; Yerokhin, Vladimir A

2010-02-19

We report a calculation of the fine-structure splitting in light heliumlike atoms, which accounts for all quantum electrodynamical effects up to order alpha{5} Ry. For the helium atom, we resolve the previously reported disagreement between theory and experiment and determine the fine-structure constant with an accuracy of 31 ppb. The calculational results are extensively checked by comparison with the experimental data for different nuclear charges and by evaluation of the hydrogenic limit of individual corrections.

Flux quantization in aperiodic and periodic networks

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

Behrooz, A.

1987-01-01

The phase boundary of quasicrystalline, quasi-periodic, and random networks, was studied. It was found that if a network is composed of two different tiles, whose areas are relatively irrational, then the T/sub c/ (H) curve shows large-scale structure at fields that approximate flux quantization around the tiles, i.e., when the ratio of fluxoids contained in the large tiles to those in the small tiles is a rational approximant to the irrational area ratio. The phase boundaries of quasi-crystalline and quasi-periodic networks show fine structure indicating the existence of commensurate vortex superlattices on these networks. No such fine structure is foundmore » on the random array. For a quasi-crystal whose quasi-periodic long-range order is characterized by the irrational number of tau, the commensurate vortex lattices are all found at H = H/sub 0/ absolute value n + m tau (n,m integers). It was found that the commensurate superlattices on quasicrystalline as well as on crystalline networks are related to the inflation symmetry. A general definition of commensurability is proposed.« less

An integrated approach using orthogonal analytical techniques to characterize heparan sulfate structure.

PubMed

Beccati, Daniela; Lech, Miroslaw; Ozug, Jennifer; Gunay, Nur Sibel; Wang, Jing; Sun, Elaine Y; Pradines, Joël R; Farutin, Victor; Shriver, Zachary; Kaundinya, Ganesh V; Capila, Ishan

2017-02-01

Heparan sulfate (HS), a glycosaminoglycan present on the surface of cells, has been postulated to have important roles in driving both normal and pathological physiologies. The chemical structure and sulfation pattern (domain structure) of HS is believed to determine its biological function, to vary across tissue types, and to be modified in the context of disease. Characterization of HS requires isolation and purification of cell surface HS as a complex mixture. This process may introduce additional chemical modification of the native residues. In this study, we describe an approach towards thorough characterization of bovine kidney heparan sulfate (BKHS) that utilizes a variety of orthogonal analytical techniques (e.g. NMR, IP-RPHPLC, LC-MS). These techniques are applied to characterize this mixture at various levels including composition, fragment level, and overall chain properties. The combination of these techniques in many instances provides orthogonal views into the fine structure of HS, and in other instances provides overlapping / confirmatory information from different perspectives. Specifically, this approach enables quantitative determination of natural and modified saccharide residues in the HS chains, and identifies unusual structures. Analysis of partially digested HS chains allows for a better understanding of the domain structures within this mixture, and yields specific insights into the non-reducing end and reducing end structures of the chains. This approach outlines a useful framework that can be applied to elucidate HS structure and thereby provides means to advance understanding of its biological role and potential involvement in disease progression. In addition, the techniques described here can be applied to characterization of heparin from different sources.

Characterization of CuHal-intercalated carbon nanotubes with x-ray absorption spectroscopy combined with x-ray photoelectron and resonant photoemission spectroscopies

NASA Astrophysics Data System (ADS)

Brzhezinskaya, M.; Generalov, A.; Vinogdradov, A.; Eliseev, A.

2013-04-01

Encapsulated single-walled carbon nanotubes (SWCNTs) with inner channels filled by different compounds present the new class of composite materials. Such CNTs give opportunity to form 1D nanocrystals as well as quantum nanowires with new physical and chemical properties inside the tubes. The present study is aimed to characterize the possible chemical interaction between CuHal (Hal=I, Cl, Br) and SWCNTs in CuHal@SWCNTs and electronic structure of the latter using high-resolution near edge X-ray absorption fine structure (NEXAFS) spectroscopy combined with high-resolution X-ray photoelectron spectroscopy and resonant photoemission spectroscopy. The present study has shown that there is a chemical interaction between the filler and π-electron subsystem of CNTs which is accompanied by changes of the atomic and electronic structure of the filler during the encapsulating it inside CNTs.

Electronic structure and magnetic properties of Ni-doped SnO2 thin films

NASA Astrophysics Data System (ADS)

Sharma, Mayuri; Kumar, Shalendra; Alvi, P. A.

2018-05-01

This paper reports the electronic structure and magnetic properties of Ni-doped SnO2 thin film which were grown on Si (100) substrate by PLD (pulse laser deposition) technique under oxygen partial pressure (PO2). For getting electronic structure and magnetic behavior, the films were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DC magnetization measurements. The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni2+ ions in the system.

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

Li, Shuning; Roy, Amitava; Lichtenberg, Henning

The micro-segmented flow technique was applied for continuous synthesis of ZnO micro- and nanoparticles with short residence times of 9.4 s and 21.4 s, respectively. The obtained particles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Small angle X-ray scattering (SAXS) and photoluminescence spectroscopy were used to determine the size and optical properties of ZnO nanoparticles. In addition, extended X-ray absorption fine structure (EXAFS) spectroscopy was employed to investigate local structural properties. The EXAFS measurements reveal a larger degree of structural disorder in the nanoparticles than the microparticles. These structural changes should be taken into considerationmore » while evaluating the size-dependent visible emission of ZnO nanoparticles.« less

Infrared laser spectroscopy of jet-cooled carbon clusters: structure of triplet C6

NASA Technical Reports Server (NTRS)

Hwang, H. J.; Van Orden, A.; Tanaka, K.; Kuo, E. W.; Heath, J. R.; Saykally, R. J.

1993-01-01

We report the first structural characterization of the triplet isomer of C6. Forty-one rovibrational/fine structure transitions in the nu 4(sigma u) antisymmetric stretch fundamental of the C6 cluster have been measured by diode laser absorption spectroscopy of a supersonic carbon cluster beam. The observed spectrum is characteristic of a centrosymmetric linear triplet state with cumulene-type bonding. The measured ground state rotational constant B0 = 0.048 479 (10)cm-1 and the effective bond length r(eff) = 1.2868 (1) angstroms are in good agreement with ab initio predictions for the linear triplet (3 sigma g-) state of C6.

Synthesis and x-ray characterization of cobalt phosphide (Co₂P) nanorods for the oxygen reduction reaction

DOE PAGES

Doan-Nguyen, Vicky V.T.; Su, Dong; Zhang, Sen; ...

2015-07-14

Low temperature fuel cells are clean, effective alternative fuel conversion technology. Oxygen reduction reaction (ORR) at the fuel cell cathode has required Pt as the electrocatalyst for high activity and selectivity of the four-electron reaction pathway. Targeting a less expensive, earth abundant alternative, we have developed the synthesis of cobalt phosphide (Co₂P) nanorods for ORR. Characterization techniques that include total X-ray scattering and extended X-ray absorption fine structure revealed a deviation of the nanorods from bulk crystal structure with a contraction along the b orthorhombic lattice parameter. The carbon supported nanorods have comparable activity but are remarkably more stable thanmore » conventional Pt catalysts for the oxygen reduction reaction in alkaline environments.« less

CHARACTERIZATION OF FINE PARTICULATE MATTER

EPA Science Inventory

Size distribution data processing and fitting
Ultrafine, very fine and fine PM were collected nearly continuously from December 2000 through March 2003 at a Washington State Department of Ecology site on Beacon Hill in Seattle. Particle size distributio...

Bimetallic iron and cobalt incorporated MFI/MCM-41 composite and its catalytic properties

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

Li, Baoshan, E-mail: bsli@mail.buct.edu.cn; Xu, Junqing; Li, Xiao

2012-05-15

Graphical abstract: The formation of FeCo-MFI/MCM-41 composite is based on two steps, the first step of synthesizing the MFI-type proto-zeolite unites under hydrothermal conditions. The second step of assembling these zeolite fragment together new silica and heteroatom source on the CTAB surfactant micelle to synthesize the mesoporous product with hexagonal structure. Highlights: Black-Right-Pointing-Pointer Bimetallic iron and cobalt incorporated MFI/MCM-41 composite was prepared using templating method. Black-Right-Pointing-Pointer FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of meso- and micro-porous structures. Black-Right-Pointing-Pointer Iron and cobalt ions incorporated into the silica framework with tetrahedral coordination. -- Abstract: The MFI/MCM-41 composite material with bimetallic Fe andmore » Co incorporation was prepared using templating method via a two-step hydrothermal crystallization procedure. The obtained products were characterized by a series of techniques including powder X-ray diffraction, N{sub 2} sorption, transmission electron microscopy, scanning electron microscope, H{sub 2} temperature programmed reduction, thermal analyses, and X-ray absorption fine structure spectroscopy of the Fe and Co K-edge. The catalytic properties of the products were investigated by residual oil hydrocracking reactions. Characterization results showed that the FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of stable meso- and micro-porous structures. Iron and cobalt ions were incorporated into the silicon framework, which was confirmed by H{sub 2} temperature programmed reduction and X-ray absorption fine structure spectroscopy. This composite presented excellent activities in hydrocracking of residual oil, which was superior to the pure materials of silicate-1/MCM-41.« less

Multi-scale Multi-dimensional Imaging and Characterization of Oil Shale Pyrolysis

NASA Astrophysics Data System (ADS)

Gao, Y.; Saif, T.; Lin, Q.; Al-Khulaifi, Y.; Blunt, M. J.; Bijeljic, B.

2017-12-01

The microstructural evaluation of fine grained rocks is challenging which demands the use of several complementary methods. Oil shale, a fine-grained organic-rich sedimentary rock, represents a large and mostly untapped unconventional hydrocarbon resource with global reserves estimated at 4.8 trillion barrels. The largest known deposit is the Eocene Green River Formation in Western Colorado, Eastern Utah, and Southern Wyoming. An improved insight into the mineralogy, organic matter distribution and pore network structure before, during and after oil shale pyrolysis is critical to understanding hydrocarbon flow behaviour and improving recovery. In this study, we image Mahogany zone oil shale samples in two dimensions (2-D) using scanning electron microscopy (SEM), and in three dimensions (3-D) using focused ion beam scanning electron microscopy (FIB-SEM), laboratory-based X-ray micro-tomography (µCT) and synchrotron X-ray µCT to reveal a complex and variable fine grained microstructure dominated by organic-rich parallel laminations which are tightly bound in a highly calcareous and heterogeneous mineral matrix. We report the results of a detailed µCT study of the Mahogany oil shale with increasing pyrolysis temperature. The physical transformation of the internal microstructure and evolution of pore space during the thermal conversion of kerogen in oil shale to produce hydrocarbon products was characterized. The 3-D volumes of pyrolyzed oil shale were reconstructed and image processed to visualize and quantify the volume and connectivity of the pore space. The results show a significant increase in anisotropic porosity associated with pyrolysis between 300-500°C with the formation of micron-scale connected pore channels developing principally along the kerogen-rich lamellar structures.

Grain refinement of 7075Al alloy microstructures by inoculation with Al-Ti-B master alloy

NASA Astrophysics Data System (ADS)

Hotea, V.; Juhasz, J.; Cadar, F.

2017-05-01

This paper aims to bring some clarification on grain refinement and modification of high strength alloys used in aerospace technique. In this work it was taken into account 7075 Al alloy, and the melt treatment was carried out by placing in the form of master alloy wire ternary AlTiB the casting trough at 730°C. The morphology of the resulting microstructures was characterized by optical microscopy. Micrographs unfinished and finished with pre-alloy containing ternary Al5Ti1B evidence fine crystals, crystal containing no columnar structure and highlights the size of the dendrites, and intermetallic phases occurring at grain boundaries in Al-Zn-Mg-Cu alloy. It has been found that these intermetallic compounds are MgZn2 type. AlTiB master alloys finishing ensures a fine eutectic structure, which determines the properties of hardware and improving the mechanical properties of aluminum alloys used in aeronautical engineering.

Fine root dynamics and trace gas fluxes in two lowland tropical forest soils.

Treesearch

WHENDEE L. SILVER; ANDREW W. THOMPSON; MEGAN E . MCGRODDY; RUTH K. VARNER; JADSON D. DIAS; HUDSON SILVA; CRILL PATRICK M.; MICHAEL KELLER

2005-01-01

Fine root dynamics have the potential to contribute significantly to ecosystem-scale biogeochemical cycling, including the production and emission of greenhouse gases. This is particularly true in tropical forests which are often characterized as having large fine root biomass and rapid rates of root production and decomposition. We examined patterns in fine root...

Morphological assessment of bone mineralization in tibial metaphyses of ascorbic acid-deficient ODS rats.

PubMed

Hasegawa, Tomoka; Li, Minqi; Hara, Kuniko; Sasaki, Muneteru; Tabata, Chihiro; de Freitas, Paulo Henrique Luiz; Hongo, Hiromi; Suzuki, Reiko; Kobayashi, Masatoshi; Inoue, Kiichiro; Yamamoto, Tsuneyuki; Oohata, Noboru; Oda, Kimimitsu; Akiyama, Yasuhiro; Amizuka, Norio

2011-08-01

Osteogenic disorder shionogi (ODS) rats carry a hereditary defect in ascorbic acid synthesis, mimicking human scurvy when fed with an ascorbic acid-deficient (aa-def) diet. As aa-def ODS rats were shown to feature disordered bone formation, we have examined the bone mineralization in this rat model. A fibrous tissue layer surrounding the trabeculae of tibial metaphyses was found in aa-def ODS rats, and this layer showed intense alkaline phosphatase activity and proliferating cell nuclear antigen-immunopositivity. Many osteoblasts detached from the bone surfaces and were characterized by round-shaped rough endoplasmic reticulum (rER), suggesting accumulation of malformed collagen inside the rER. Accordingly, fine, fragile fibrillar collagenous structures without evident striation were found in aa-def bones, which may result from misassembling of the triple helices of collagenous α-chains. Despite a marked reduction in bone formation, ascorbic acid deprivation seemed to have no effect on mineralization: while reduced in number, normal matrix vesicles and mineralized nodules could be seen in aa-def bones. Fine needle-like mineral crystals extended from these mineralized nodules, and were apparently bound to collagenous fibrillar structures. In summary, collagen mineralization seems unaffected by ascorbic acid deficiency in spite of the fine, fragile collagenous fibrils identified in the bones of our animal model.

Complex Ancient Genetic Structure and Cultural Transitions in Southern African Populations.

PubMed

Montinaro, Francesco; Busby, George B J; Gonzalez-Santos, Miguel; Oosthuitzen, Ockie; Oosthuitzen, Erika; Anagnostou, Paolo; Destro-Bisol, Giovanni; Pascali, Vincenzo L; Capelli, Cristian

2017-01-01

The characterization of the structure of southern African populations has been the subject of numerous genetic, medical, linguistic, archaeological, and anthropological investigations. Current diversity in the subcontinent is the result of complex events of genetic admixture and cultural contact between early inhabitants and migrants that arrived in the region over the last 2000 years. Here, we analyze 1856 individuals from 91 populations, comprising novel and published genotype data, to characterize the genetic ancestry profiles of 631 individuals from 51 southern African populations. Combining both local ancestry and allele frequency based analyses, we identify a tripartite, ancient, Khoesan-related genetic structure. This structure correlates neither with linguistic affiliation nor subsistence strategy, but with geography, revealing the importance of isolation-by-distance dynamics in the area. Fine-mapping of these components in southern African populations reveals admixture and cultural reversion involving several Khoesan groups, and highlights that Bantu speakers and Coloured individuals have different mixtures of these ancient ancestries. Copyright © 2017 Montinaro et al.

Laboratory characterization of shale pores

NASA Astrophysics Data System (ADS)

Nur Listiyowati, Lina

2018-02-01

To estimate the potential of shale gas reservoir, one needs to understand the characteristics of pore structures. Characterization of shale gas reservoir microstructure is still a challenge due to ultra-fine grained micro-fabric and micro level heterogeneity of these sedimentary rocks. The sample used in the analysis is a small portion of any reservoir. Thus, each measurement technique has a different result. It raises the question which methods are suitable for characterizing pore shale. The goal of this paper is to summarize some of the microstructure analysis tools of shale rock to get near-real results. The two analyzing pore structure methods are indirect measurement (MIP, He, NMR, LTNA) and direct observation (SEM, TEM, Xray CT). Shale rocks have a high heterogeneity; thus, it needs multiscale quantification techniques to understand their pore structures. To describe the complex pore system of shale, several measurement techniques are needed to characterize the surface area and pore size distribution (LTNA, MIP), shapes, size and distribution of pore (FIB-SEM, TEM, Xray CT), and total porosity (He pycnometer, NMR). The choice of techniques and methods should take into account the purpose of the analysis and also the time and budget.

An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

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

Song, Zhen; Kenney, Janice P.L.; Fein, Jeremy B.

2015-02-09

Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has beenmore » observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.« less

An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

NASA Astrophysics Data System (ADS)

Song, Zhen; Kenney, Janice P. L.; Fein, Jeremy B.; Bunker, Bruce A.

2012-06-01

Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has been observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.

Structural Characterization of Sm(III)(EDTMP).

PubMed

Yang, Y; Pushie, M J; Cooper, D M L; Doschak, M R

2015-11-02

Samarium-153 ethylenediamine-N,N,N',N'-tetrakis(methylenephosphonic acid) ((153)Sm-EDTMP, or samarium lexidronam), also known by its registered trademark name Quadramet, is an approved therapeutic radiopharmaceutical used in the palliative treatment of painful bone metastases. Typically, patients with prostate, breast, or lung cancer are most likely to go on to require bone pain palliation treatment due to bone metastases. Sm(EDTMP) is a bone-seeking drug which accumulates on rapidly growing bone, thereby delivering a highly region-specific dose of radiation, chiefly through β particle emission. Even with its widespread clinical use, the structure of Sm(EDTMP) has not yet been characterized at atomic resolution, despite attempts to crystallize the complex. Herein, we prepared a 1:1 complex of the cold (stable isotope) of Sm(EDTMP) under alkaline conditions and then isolated and characterized the complex using conventional spectroscopic techniques, as well as with extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional structure calculations, using natural abundance Sm. We present the atomic resolution structure of [Sm(III)(EDTMP)-8H](5-) for the first time, supported by the EXAFS data and complementary spectroscopic techniques, which demonstrate that the samarium coordination environment in solution is in agreement with the structure that has long been conjectured.

Fine structural features of nanoscale zero-valent iron characterized by spherical aberration corrected scanning transmission electron microscopy (Cs-STEM).

PubMed

Liu, Airong; Zhang, Wei-xian

2014-09-21

An angstrom-resolution physical model of nanoscale zero-valent iron (nZVI) is generated with a combination of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) on the Fe L-edge. Bright-field (BF), high-angle annular dark-field (HAADF) and secondary electron (SE) imaging of nZVI acquired by a Hitachi HD-2700 STEM show near atomic resolution images and detailed morphological and structural information of nZVI. The STEM-EDS technique confirms that the fresh nZVI comprises of a metallic iron core encapsulated with a thin layer of iron oxides or oxyhydroxides. SAED patterns of the Fe core suggest the polycrystalline structure in the metallic core and amorphous nature of the oxide layer. Furthermore, Fe L-edge of EELS shows varied structural features from the innermost Fe core to the outer oxide shell. A qualitative analysis of the Fe L(2,3) edge fine structures reveals that the shell of nZVI consists of a mixed Fe(II)/Fe(III) phase close to the Fe (0) interface and a predominantly Fe(III) at the outer surface of nZVI.

Cortico-Cerebellar Structural Connectivity Is Related to Residual Motor Output in Chronic Stroke.

PubMed

Schulz, Robert; Frey, Benedikt M; Koch, Philipp; Zimerman, Maximo; Bönstrup, Marlene; Feldheim, Jan; Timmermann, Jan E; Schön, Gerhard; Cheng, Bastian; Thomalla, Götz; Gerloff, Christian; Hummel, Friedhelm C

2017-01-01

Functional imaging studies have argued that interactions between cortical motor areas and the cerebellum are relevant for motor output and recovery processes after stroke. However, the impact of the underlying structural connections is poorly understood. To investigate this, diffusion-weighted brain imaging was conducted in 26 well-characterized chronic stroke patients (aged 63 ± 1.9 years, 18 males) with supratentorial ischemic lesions and 26 healthy participants. Probabilistic tractography was used to reconstruct reciprocal cortico-cerebellar tracts and to relate their microstructural integrity to residual motor functioning applying linear regression modeling. The main finding was a significant association between cortico-cerebellar structural connectivity and residual motor function, independent from the level of damage to the cortico-spinal tract. Specifically, white matter integrity of the cerebellar outflow tract, the dentato-thalamo-cortical tract, was positively related to both general motor output and fine motor skills. Additionally, the integrity of the descending cortico-ponto-cerebellar tract contributed to rather fine motor skills. A comparable structure-function relationship was not evident in the controls. The present study provides first tract-related structural data demonstrating a critical importance of distinct cortico-cerebellar connections for motor output after stroke. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Understanding Superfine Graphite Iron Solidification Through Interrupted Solidification Experiments

NASA Astrophysics Data System (ADS)

Alonso, G.; Stefanescu, D. M.; Larrañaga, P.; De la Fuente, E.; Aguado, E.; Suarez, R.

The tensile strength of near-eutectic gray iron can be increased from 230-300 to 300-345MPa, without a significant increase in hardness, through 0.3-0.4%Ti addition to low sulfur (<0.01%S) iron. This is due to the combination of higher primary austenite/eutectic ratio and the precipitation of superfine-interdendritic-graphite (SIG), characterized by a fine (10-20μm) and highly branched fibrous structure.

Fabrication of High-Performance Polymer Bulk-Heterojunction Solar Cells by the Interfacial Modifications III

DTIC Science & Technology

2011-04-30

University of Tennessee) 3. "An ambipolar to n-type transformation in pentacene -based organic field-effect transistors" Org. Electron. 12, 509 (2011...OFETs). An ambipolar to n-type transformation in pentacene -based organic field-effect transistors (OFETs) of Al source-drain electrodes had been...correlated with the interfacial interactions between Al electrodes and pentacene , as characterized by analyzing Near-edge X-ray absorption fine structure

Synthesis, characterization and magnetic properties of MFe2O4 (M=Co, Mg, Mn, Ni) nanoparticles using ricin oil as capping agent

NASA Astrophysics Data System (ADS)

Gherca, Daniel; Pui, Aurel; Cornei, Nicoleta; Cojocariu, Alina; Nica, Valentin; Caltun, Ovidiu

2012-11-01

We focused on obtaining MFe2O4 nanoparticles using ricin oil solution as surfactant and on their structural characterization and magnetic properties. The annealed samples at 500 °C in air for 6 h were analyzed for the crystal phase identification by powder X-ray diffraction using CuKα radiation. The particle size, the chemical composition and the morphology of the calcinated powders were characterized by scanning electron microscopy. All sintered samples contain only one phase, which has a cubic structure with crystallite sizes of 12-21 nm. From the infrared spectra of all samples were observed two strong bands around 600 and 400 cm-1, which correspond to the intrinsic lattice vibrations of octahedral and tetrahedral sites of the spinel structure, respectively, and characteristic vibration for capping agent. The magnetic properties of fine powders were investigated at room temperature by using a vibrating sample magnetometer. The room temperature M-H hysteresis loops show ferromagnetic behavior of the calcined samples, with specific saturation magnetization (Ms) values ranging between 11 and 53 emu/g.

Effects of interaural time differences in fine structure and envelope on lateral discrimination in electric hearing.

PubMed

Majdak, Piotr; Laback, Bernhard; Baumgartner, Wolf-Dieter

2006-10-01

Bilateral cochlear implant (CI) listeners currently use stimulation strategies which encode interaural time differences (ITD) in the temporal envelope but which do not transmit ITD in the fine structure, due to the constant phase in the electric pulse train. To determine the utility of encoding ITD in the fine structure, ITD-based lateralization was investigated with four CI listeners and four normal hearing (NH) subjects listening to a simulation of electric stimulation. Lateralization discrimination was tested at different pulse rates for various combinations of independently controlled fine structure ITD and envelope ITD. Results for electric hearing show that the fine structure ITD had the strongest impact on lateralization at lower pulse rates, with significant effects for pulse rates up to 800 pulses per second. At higher pulse rates, lateralization discrimination depended solely on the envelope ITD. The data suggest that bilateral CI listeners benefit from transmitting fine structure ITD at lower pulse rates. However, there were strong interindividual differences: the better performing CI listeners performed comparably to the NH listeners.

A New Maraging Stainless Steel with Excellent Strength-Toughness-Corrosion Synergy.

PubMed

Tian, Jialong; Wang, Wei; Babar Shahzad, M; Yan, Wei; Shan, Yiyin; Jiang, Zhouhua; Yang, Ke

2017-11-10

A new maraging stainless steel with superior strength-toughness-corrosion synergy has been developed based on an innovative concept of alloy design. The high strength-toughness combination is achieved by forming dispersive nano-sized intermetallic compounds in the soft lath martensitic matrix with a slight amount of residual austenite. The good corrosion resistance is guaranteed by exactly controlling the Co content based on understanding the synergistic effect between Co and Cr. The fine structure characteristics of two dominant strengthening precipitations including Ni₃Ti and Mo-rich phases were finely characterized associated with transmission electron microscope (TEM) and atom probe tomography (APT) analyses. The relationship among microstructure, strength and toughness is discussed. The precipitation mechanism of different precipitates in the new maraging stainless steel is revealed based on the APT analysis.

Fine motor skills predict performance in the Jebsen Taylor Hand Function Test after stroke.

PubMed

Allgöwer, Kathrin; Hermsdörfer, Joachim

2017-10-01

To determine factors characterizing the differences in fine motor performance between stroke patients and controls. To confirm the relevance of the factors by analyzing their predictive power with regard to the Jebsen Taylor Hand Function Test (JTHFT), a common clinical test of fine motor control. Twenty-two people with slight paresis in an early chronic phase following stroke and twenty-two healthy controls were examined. Performance on the JTHFT, Nine-Hole Peg Test and 2-point discrimination was evaluated. To analyze object manipulation skills, grip forces and temporal measures were examined during (1) lifting actions with variations of weight and surface (2) cyclic movements (3) predictive/reactive catching tasks. Three other aspects of force control included (4) visuomotor tracking (5) fast force changes and (6) grip strength. Based on 9 parameters which significantly distinguished fine motor performance in the two groups, we identified three principal components (factors): grip force scaling, motor coordination and speed of movement. The three factors are shown to predict JTHFT scores via linear regression (R 2 =0.687, p<0.001). We revealed a factor structure behind fine motor impairments following stroke and showed that it explains JTHFT results to a large extend. This result can serve as a basis for improving diagnostics and enabling more targeted therapy. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

[The role of temporal fine structure in tone recognition and music perception].

PubMed

Zhou, Q; Gu, X; Liu, B

2017-11-07

The sound signal can be decomposed into temporal envelope and temporal fine structure information. The temporal envelope information is crucial for speech perception in quiet environment, and the temporal fine structure information plays an important role in speech perception in noise, Mandarin tone recognition and music perception, especially the pitch and melody perception.

Willis Lamb, Jr., the Hydrogen Atom, and the Lamb Shift

Science.gov Websites

1955, Lamb won the Nobel Prize in Physics for his discoveries concerning "the fine structure of , May 7 - September 30, 1979 Fine Structure of the Hydrogen Atom, Part I; Part II; Part III; Part IV ; Part V; Part VI (from Physical Review 1950-1953) Microwave Technique for Determining the Fine Structure

Atomic force microscopy based nanoassay: a new method to study α-Synuclein-dopamine bioaffinity interactions

NASA Astrophysics Data System (ADS)

Corvaglia, Stefania; Sanavio, Barbara; Sorce, Barbara; Bosco, Alessandro; Sabella, Stefania; Pompa, Pierpaolo; Scoles, Giacinto; Casalis, Loredana

2015-03-01

Intrinsically Disordered Proteins (IDPs) are characterized by the lack of well-defined 3-D structure and show high conformational plasticity. For this reason, they are a strong challenge for the traditional characterization of structure, supramolecular assembly and biorecognition phenomena. We show here how the fine tuning of protein orientation on a surface turns useful in the reliable testing of biorecognition interactions of IDPs, in particular α-Synuclein. We exploited atomic force microscopy (AFM) for the selective, nanoscale confinement of α-Synuclein on gold to study the early stages of α-Synuclein aggregation and the effect of small molecules, like dopamine, on the aggregation process. Capitalizing on the high sensitivity of AFM topographic height measurements we determined, for the first time in the literature, the dissociation constant of dopamine- α-Synuclein adducts.

Atomic force microscopy based nanoassay: a new method to study α-Synuclein-dopamine bioaffinity interactions

NASA Astrophysics Data System (ADS)

Corvaglia, Stefania; Sanavio, Barbara; Hong Enriquez, Rolando P.; Sorce, Barbara; Bosco, Alessandro; Scaini, Denis; Sabella, Stefania; Pompa, Pier Paolo; Scoles, Giacinto; Casalis, Loredana

2014-06-01

Intrinsically Disordered Proteins (IDPs) are characterized by the lack of well-defined 3-D structure and show high conformational plasticity. For this reason, they are a strong challenge for the traditional characterization of structure, supramolecular assembly and biorecognition phenomena. We show here how the fine tuning of protein orientation on a surface turns useful in the reliable testing of biorecognition interactions of IDPs, in particular α-Synuclein. We exploited atomic force microscopy (AFM) for the selective, nanoscale confinement of α-Synuclein on gold to study the early stages of α-Synuclein aggregation and the effect of small molecules, like dopamine, on the aggregation process. Capitalizing on the high sensitivity of AFM topographic height measurements we determined, for the first time in the literature, the dissociation constant of dopamine-α-Synuclein adducts.

A Novel Method for Measurement and Characterization of Soil Macroporosity

Treesearch

Christopher Barton; Tasos Karathanasis

2002-01-01

Quantitative macropore characterizations were performed in large zero-tension soil lysimeters of a Maury silt loam (fine, mixed, mesic Typic Paleudalf) and a Loradale silt loam (fine, silty, mixed, mesic Typic Axgiudoll) soil in an effort to assess potential colloid transport. Steel pipe sections (50 cm diameter X 100 cm length) were hydraulically driven into the soil...

CHARACTERIZING THE SOURCES OF HUMAN EXPOSURE TO MUTAGENIC AND CARCINOGENIC CHEMICALS IN AIRBORNE FINE PARTICLES

EPA Science Inventory

Personal and ambient exposures to airborne fine particles, polycyclic aromatic hydrocarbons (PAH), and genotoxic activity has been studied in populations in the US, Japan, China, and the Czech Republic. Personal exposure monitors used to collect fine particles were extracted f...

Interdisciplinary research and development on the effects of the nature and properties of ceramic materials in the design of advanced structural components

NASA Technical Reports Server (NTRS)

1978-01-01

An educational development and supportive research program on ceramic materials established to advance design methodology, improve materials, and develop engineers knowledgable in design with and use of high performance ceramic materials is described. Emphasis is on the structures and related materials problems in a ceramic turbine engine, but applications in coal gasification, solar conversion, and magnetohydrodynamic technologies are considered. Progress of various research projects in the areas of new materials, processing, characterization, and nondestructive testing is reported. Fracture toughness determination, extended X-ray absorption fine structure measurements, and grain boundary effects in beta-alumina are among the topics covered.

Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

PubMed Central

Lu, Man; Wang, Xingxing; Sun, Guowei; Qin, Bing; Xiao, Jinzhou; Yan, Shuling; Pan, Yingjie; Wang, Yongjie

2014-01-01

Tibetan kefir grains (TKGs), a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i) yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii) the diversity of yeasts is relatively low on genus level with three dominant species – Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii) S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic associations between S. cerevisiae and Lactobacillus bacteria in TKGs. PMID:24977409

Structural Characterization of Poorly-Crystalline Scorodite, Iron (III)-arsenate Co-precipitates and Uranium Millneutralized Raffinate Solids using X-ray Absorption Fine Structure Spectroscopy

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

Chen, N.; Jiang, D; Cutler, J

X-ray absorption fine structure (XAFS) is used to characterize the mineralogy of the iron(III)-arsenate(V) precipitates produced during the raffinate (aqueous effluent) neutralization process at the McClean Lake uranium mill in northern Saskatchewan, Canada. To facilitate the structural characterization of the precipitated solids derived from the neutralized raffinate, a set of reference compounds were synthesized and analyzed. The reference compounds include crystalline scorodite, poorly-crystalline scorodite, iron(III)-arsenate co-precipitates obtained under different pH conditions, and arsenate-adsorbed on goethite. The poorly-crystalline scorodite (prepared at pH 4 with Fe/As = 1) has similar As local structure as that of crystalline scorodite. Both As and Femore » K-edge XAFS of poorly-crystalline scorodite yield consistent results on As-Fe (or Fe-As) shell. From As K-edge analysis the As-Fe shell has an inter-atomic distance of 3.33 {+-} 0.02 A and coordination number of 3.2; while from Fe K-edge analysis the Fe-As distance and coordination number are 3.31 {+-} 0.02 A and 3.8, respectively. These are in contrast with the typical arsenate adsorption on bidentate binuclear sites on goethite surfaces, where the As-Fe distance is 3.26 {+-} 0.03 A and coordination number is close to 2. A similar local structure identified in the poorly-crystalline scorodite is also found in co-precipitation solids (Fe(III)/As(V) = 3) when precipitated at the same pH (pH = 4): As-Fe distance 3.30 {+-} 0.03 A and coordination number 3.9; while at pH = 8 the co-precipitate has As-Fe distance of 3.27 {+-} 0.03 A and coordination number about 2, resembling more closely the adsorption case. The As local structure in the two neutralized raffinate solid series (precipitated at pH values up to 7) closely resembles that in the poorly-crystalline scorodite. All of the raffinate solids have the same As-Fe inter-atomic distance as that in the poorly-crystalline scorodite, and a systematic decrease in the As-Fe coordination is observed when pH is progressively increased; the basic poorly-crystalline scorodite structural feature remains in the raffinate solid up to pH 7.« less

Structural characterization of poorly-crystalline scorodite, iron(III)-arsenate co-precipitates and uranium mill neutralized raffinate solids using X-ray absorption fine structure spectroscopy

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

Chen, N; Jiang, D T; Cutler, J

X-ray absorption fine structure (XAFS) is used to characterize the mineralogy of the iron(III)-arsenate(V) precipitates produced during the raffinate (aqueous effluent) neutralization process at the McClean Lake uranium mill in northern Saskatchewan, Canada. To facilitate the structural characterization of the precipitated solids derived from the neutralized raffinate, a set of reference compounds were synthesized and analyzed. The reference compounds include crystalline scorodite, poorly-crystalline scorodite, iron(III)-arsenate co-precipitates obtained under different pH conditions, and arsenate-adsorbed on goethite. The poorly-crystalline scorodite (prepared at pH 4 with Fe/As = 1) has similar As local structure as that of crystalline scorodite. Both As and Femore » K-edge XAFS of poorly-crystalline scorodite yield consistent results on As-Fe (or Fe-As) shell. From As K-edge analysis the As-Fe shell has an inter-atomic distance of 3.33 ± 0.02 Å and coordination number of 3.2; while from Fe K-edge analysis the Fe-As distance and coordination number are 3.31 ± 0.02 Å and 3.8, respectively. These are in contrast with the typical arsenate adsorption on bidentate binuclear sites on goethite surfaces, where the As-Fe distance is 3.26 ± 0.03 Å and coordination number is close to 2. A similar local structure identified in the poorly-crystalline scorodite is also found in co-precipitation solids (Fe(III)/As(V) = 3) when precipitated at the same pH (pH = 4): As-Fe distance 3.30 ± 0.03 Å and coordination number 3.9; while at pH = 8 the co-precipitate has As-Fe distance of 3.27 ± 0.03 Å and coordination number about 2, resembling more closely the adsorption case. The As local structure in the two neutralized raffinate solid series (precipitated at pH values up to 7) closely resembles that in the poorly-crystalline scorodite. All of the raffinate solids have the same As-Fe inter-atomic distance as that in the poorly-crystalline scorodite, and a systematic decrease in the As-Fe coordination is observed when pH is progressively increased; the basic poorly-crystalline scorodite structural feature remains in the raffinate solid up to pH 7.« less

Protecting Secure Facilities From Underground Intrusion Using Seismic/Acoustic Sensor Arrays

DTIC Science & Technology

2009-08-01

the upper 6 meters of sediments were deposited as part of a delta during a time of higher sea level, when low-gradient rivers carried fine-grained...geological site characterization and stratigraphy and sedimentation processes. Dr. Jason R. McKenna is a geophysicist at the United States Army Engineer...doctrine is being revised to address the engineer force structure at all levels to ensure that emerging lessons learned from Iraq and Afghanistan are

Microstructural characterization of Ni-based self-fluxing alloy after selective surface-engineering using diode laser

NASA Astrophysics Data System (ADS)

Chun, Eun-Joon; Park, Changkyoo; Nishikawa, Hiroshi; Kim, Min-Su

2018-06-01

The microstructural characterization of thermal-sprayed Ni-based self-fluxing alloy (Metco-16C®) after laser-assisted homogenization treatment was performed. To this end, a high-power diode laser system was used. This supported the real-time control of the target homogenization temperature at the substrate surface. Non-homogeneities of the macrosegregation of certain elements (C and Cu) and the local concentration of Cr-based carbides and borides in certain regions in the as-sprayed state could be enhanced with the application of homogenization. After homogenization at 1423 K, the hardness of the thermal-sprayed layer was found to have increased by 1280 HV from the as-sprayed state (750 HV). At this homogenization temperature, the microstructure of the thermal-sprayed layer consisted of a lamellar structuring of the matrix phase (austenite and Ni3Si) with fine (<5 μm) carbides and borides (the rod-like phase of Cr5B3, the lumpy phase of M23C6, and the extra-fine phase of M7C3). Despite the formation of several kinds of carbides and borides during homogenization at 1473 K, the lowest hardness level was found to be less than that of the as-sprayed state, because of the liquid-state homogenization treatment without formation of lamellar structuring between austenite and Ni3Si.

Fine-Scale Analysis Reveals Cryptic Landscape Genetic Structure in Desert Tortoises

PubMed Central

Latch, Emily K.; Boarman, William I.; Walde, Andrew; Fleischer, Robert C.

2011-01-01

Characterizing the effects of landscape features on genetic variation is essential for understanding how landscapes shape patterns of gene flow and spatial genetic structure of populations. Most landscape genetics studies have focused on patterns of gene flow at a regional scale. However, the genetic structure of populations at a local scale may be influenced by a unique suite of landscape variables that have little bearing on connectivity patterns observed at broader spatial scales. We investigated fine-scale spatial patterns of genetic variation and gene flow in relation to features of the landscape in desert tortoise (Gopherus agassizii), using 859 tortoises genotyped at 16 microsatellite loci with associated data on geographic location, sex, elevation, slope, and soil type, and spatial relationship to putative barriers (power lines, roads). We used spatially explicit and non-explicit Bayesian clustering algorithms to partition the sample into discrete clusters, and characterize the relationships between genetic distance and ecological variables to identify factors with the greatest influence on gene flow at a local scale. Desert tortoises exhibit weak genetic structure at a local scale, and we identified two subpopulations across the study area. Although genetic differentiation between the subpopulations was low, our landscape genetic analysis identified both natural (slope) and anthropogenic (roads) landscape variables that have significantly influenced gene flow within this local population. We show that desert tortoise movements at a local scale are influenced by features of the landscape, and that these features are different than those that influence gene flow at larger scales. Our findings are important for desert tortoise conservation and management, particularly in light of recent translocation efforts in the region. More generally, our results indicate that recent landscape changes can affect gene flow at a local scale and that their effects can be detected almost immediately. PMID:22132143

Fine-scale analysis reveals cryptic landscape genetic structure in desert tortoises.

PubMed

Latch, Emily K; Boarman, William I; Walde, Andrew; Fleischer, Robert C

2011-01-01

Characterizing the effects of landscape features on genetic variation is essential for understanding how landscapes shape patterns of gene flow and spatial genetic structure of populations. Most landscape genetics studies have focused on patterns of gene flow at a regional scale. However, the genetic structure of populations at a local scale may be influenced by a unique suite of landscape variables that have little bearing on connectivity patterns observed at broader spatial scales. We investigated fine-scale spatial patterns of genetic variation and gene flow in relation to features of the landscape in desert tortoise (Gopherus agassizii), using 859 tortoises genotyped at 16 microsatellite loci with associated data on geographic location, sex, elevation, slope, and soil type, and spatial relationship to putative barriers (power lines, roads). We used spatially explicit and non-explicit Bayesian clustering algorithms to partition the sample into discrete clusters, and characterize the relationships between genetic distance and ecological variables to identify factors with the greatest influence on gene flow at a local scale. Desert tortoises exhibit weak genetic structure at a local scale, and we identified two subpopulations across the study area. Although genetic differentiation between the subpopulations was low, our landscape genetic analysis identified both natural (slope) and anthropogenic (roads) landscape variables that have significantly influenced gene flow within this local population. We show that desert tortoise movements at a local scale are influenced by features of the landscape, and that these features are different than those that influence gene flow at larger scales. Our findings are important for desert tortoise conservation and management, particularly in light of recent translocation efforts in the region. More generally, our results indicate that recent landscape changes can affect gene flow at a local scale and that their effects can be detected almost immediately.

Glycan shield and fusion activation of a deltacoronavirus spike glycoprotein fine-tuned for enteric infections.

PubMed

Xiong, Xiaoli; Tortorici, M Alejandra; Snijder, Joost; Yoshioka, Craig; Walls, Alexandra C; Li, Wentao; McGuire, Andrew T; Rey, Félix A; Bosch, Berend-Jan; Veesler, David

2017-11-01

Coronaviruses recently emerged as major human pathogens causing outbreaks of severe acute respiratory syndrome and Middle-East respiratory syndrome. They utilize the spike (S) glycoprotein anchored in the viral envelope to mediate host attachment and fusion of the viral and cellular membranes to initiate infection. The S protein is a major determinant of the zoonotic potential of coronaviruses and is also the main target of the host humoral immune response. We report here the 3.5 Å resolution cryo-electron microscopy structure of the S glycoprotein trimer from the pathogenic porcine deltacoronavirus (PDCoV), which belongs to the recently identified delta genus. Structural and glycoproteomics data indicate that the glycans of PDCoV S are topologically conserved when compared with the human respiratory coronavirus HCoV-NL63 S, resulting in similar surface areas being shielded from neutralizing antibodies and implying that both viruses are under comparable immune pressure in their respective hosts. The structure further reveals a shortened S 2 ' activation loop, containing a reduced number of basic amino acids, which participates to rendering the spike largely protease-resistant. This property distinguishes PDCoV S from recently characterized betacoronavirus S proteins and suggests that the S protein of enterotropic PDCoV has evolved to tolerate the protease-rich environment of the small intestine and to fine-tune its fusion activation to avoid premature triggering and reduction of infectivity. IMPORTANCE Coronaviruses use transmembrane spike (S) glycoprotein trimers to promote host attachment and fusion of the viral and cellular membranes. We determined a near-atomic resolution cryo-electron microscopy structure of the S ectodomain trimer from the pathogenic porcine deltacoronavirus (PDCoV), which is responsible for diarrhea in piglets and has had devastating consequences for the swine industry worldwide. Structural and glycoproteomics data reveal that PDCoV S is decorated with 78 N-linked glycans obstructing the protein surface to limit accessibility to neutralizing antibodies in a way reminiscent of what has recently been described for a human respiratory coronavirus. PDCoV S is largely protease-resistant which distinguishes it from most other characterized coronavirus S glycoproteins and suggests that enteric coronaviruses have evolved to fine-tune fusion activation in the protease-rich environment of the small intestine of infected hosts. Copyright © 2017 American Society for Microbiology.

Statistical Fine Structure in the Inhomogeneously Broadened Electronic Origin of Pentacene in p-Terphenyl.

DTIC Science & Technology

1988-01-29

Electronic Origin of Pentacene in p-Terphenyl by T. P. Carter, M. Manavi, and W. E. Moerner Prepared for Publication inDTIC Journal of Chemical Physics...Classification) Statistical Fine Structure in the Inhomogeneously Broadened Electronic Origin of Pentacene in p-Terphenyl 12. PERSONAL AUTHOR(S) T. P...of pentacene in p-terphenyl using laser FM spectroscopy. Statistical fine structure is time-independent structure on the inhomogeneous line caused by

Statistical Fine Structure of Inhomogeneously Broadened Absorption Lines.

DTIC Science & Technology

1987-07-31

inhomogeneously broadened optical absorption of pentacene n p-terphenyl at liquid helium temperatures... SFS is the actual frequency- ependent, time...statistical fine structure (SFS) in the inhomogeneously broadened optical absorption of pentacene in p-terphenyl at liquid helium temperatures. SFS is the...quite difficult . -2- We have observed for the first time statistical fine structure in the inhomogeneously broadened optical absorption of pentacene

Large local disorder in superconducting K(0.8)Fe(1.6)Se2 studied by extended x-ray absorption fine structure.

PubMed

Iadecola, A; Joseph, B; Simonelli, L; Puri, A; Mizuguchi, Y; Takeya, H; Takano, Y; Saini, N L

2012-03-21

We have measured the local structure of superconducting K(0.8)Fe(1.6)Se(2) chalcogenide (T(c) = 31.8 K) by temperature dependent polarized extended x-ray absorption fine structure (EXAFS) at the Fe and Se K-edges. We find that the system is characterized by a large local disorder. The Fe-Se and Fe-Fe distances are found to be shorter than the distances measured by diffraction, while the corresponding mean square relative displacements reveal large Fe-site disorder and relatively large c-axis disorder. The local force constant for the Fe-Se bondlength (k ~ 5.8 eV Å(-2)) is similar to the one found in the binary FeSe superconductor, however, the Fe-Fe bondlength appears to be flexible (k ~ 2.1 eV Å(-2)) in comparison to the binary FeSe (k ~ 3.5 eV Å(-2)), an indication of partly relaxed Fe-Fe networks in K(0.8)Fe(1.6)Se(2). The results suggest a glassy nature for the title system, with the superconductivity being similar to that in the granular materials. © 2012 IOP Publishing Ltd

Reservoir characterization of Mesaverde (Campanian) bedload fluvial meanderbelt sandstones, northwestern Colorado

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

Jones, J.R. Jr.

1984-04-01

Reservoir characterization of Mesaverde meanderbelt sandstones is used to determined directional continuity of permeable zones. A 500-m (1600 ft) wide fluvial meanderbelt in the Mesaverde Group is exposed as laterally continuous 3-10-m (10-33-ft) high sandstone cliffs north of Rangely, Colorado. Forty-eight detailed measured sections through 3 point bar complexes oriented at right angles to the long axis of deposition and 1 complex oriented parallel to deposition were prepared. Sections were tied together by detailed sketches delineating and tracing major bounding surfaces such as scours and clay drapes. These complexes contain 3 to 8 multilateral sandstone packages separated by 5-20 cmmore » (2-8 in.) interbedded siltstone and shale beds. Component facies are point bars, crevasse splays, chute bars, and floodplain/overbank deposits. Two types of lateral accretion surfaces are recognized in the point bar facies. Gently dipping lateral accretions containing fining-upward sandstone packages. Large scale trough cross-bedding at the base grades upward into ripples and plane beds. Steeply dipping lateral accretion surfaces enclose beds characterized by climbing ripple cross laminations. Bounding surfaces draped by shale lags can seal vertically stacked point bars from reservoir communication. Scoured boundaries allow communication in some stacked point bars. Crevasse splays showing climbing ripples form tongues of very fine-grained sandstone which flank point bars. Chute channels commonly cut upper point bar surfaces at their downstream end. Chute facies are upward-fining with small scale troughs and common dewatering structures. Siltstones and shales underlie the point bar complexes and completely encase the meanderbelt system. Bounding surfaces at the base of the complexes are erosional and contain large shale rip-up clasts.« less

Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks

USGS Publications Warehouse

Kanno, Yoichiro; Vokoun, Jason C.; Letcher, Benjamin H.

2011-01-01

Linear and heterogeneous habitat makes headwater stream networks an ideal ecosystem in which to test the influence of environmental factors on spatial genetic patterns of obligatory aquatic species. We investigated fine-scale population structure and influence of stream habitat on individual-level genetic differentiation in brook trout (Salvelinus fontinalis) by genotyping eight microsatellite loci in 740 individuals in two headwater channel networks (7.7 and 4.4 km) in Connecticut, USA. A weak but statistically significant isolation-by-distance pattern was common in both sites. In the field, many tagged individuals were recaptured in the same 50-m reaches within a single field season (summer to fall). One study site was characterized with a hierarchical population structure, where seasonal barriers (natural falls of 1.5–2.5 m in height during summer base-flow condition) greatly reduced gene flow and perceptible spatial patterns emerged because of the presence of tributaries, each with a group of genetically distinguishable individuals. Genetic differentiation increased when pairs of individuals were separated by high stream gradient (steep channel slope) or warm stream temperature in this site, although the evidence of their influence was equivocal. In a second site, evidence for genetic clusters was weak at best, but genetic differentiation between individuals was positively correlated with number of tributary confluences. We concluded that the population-level movement of brook trout was limited in the study headwater stream networks, resulting in the fine-scale population structure (genetic clusters and clines) even at distances of a few kilometres, and gene flow was mitigated by ‘riverscape’ variables, particularly by physical barriers, waterway distance (i.e. isolation-by-distance) and the presence of tributaries.

Atomic Fine-Structure Diagnostic and Cooling Transitions for Far Infrared and Submillimeter Observations

NASA Astrophysics Data System (ADS)

Balance, Connor

Some of the strongest emission lines observed from a variety of astronomical sources originate from transitions between fine-structure levels in the ground term of neutral atoms and lowly-charged ions. These fine-structure levels are populated due to collisions with -, H+, H, He, and/or H2 depending on the temperature and ionization fraction of e the environment. As fine-structure excitation measurements are rare, modeling applications depend on theoretically determined rate coefficients. However, for many ions electron collision studies have not been performed for a decade or more, while over that time period the theoretical/computational methodology has significantly advanced. For heavy-particle collisions, very few systems have been studied. As a result, most models rely on estimates or on low-quality collisional data for fine-structure excitation. To significantly advance the state of fine-structure data for astrophysical models, we propose a collaborative effort in electron collisions, heavy-particle collisions, and quantum chemistry. Using the R-matrix method, fine-structure excitation due to electron collisions will be investigated for C, O, Ne^+, Ne^2+, Ar^+, Ar^2+, Fe, Fe^+, and Fe^2+. Fine-structure excitation due to heavy-particle collisions will be studied with a fully quantum molecular-orbital approach using potential energy surfaces computed with a multireference configuration-interaction method. The systems to be studied include: C/H^+, C/H2, O/H^+, O/H2, Ne^+/H, Ne^+/H2, Ne^2+/H, Ne^2+/H2, Fe/H^+, Fe^+/H, and Fe^2+/H. 2D rigid-rotor surfaces will be constructed for H2 collisions, internuclear distance dependent spin-orbit coupling will be computed in some cases, and all rate coefficients will be obtained for the temperature range 10-2000 K. The availability the proposed fine-structure excitation data will lead to deeper examination and understanding of the properties of many astrophysical environments, including young stellar objects, protoplanetary disks, planetary nebulae, photodissociation regions, active galactic nuclei, and x-ray dominated regions, hence elevating the scientific return from current (SOFIA, Spitzer, Herschel, HST) and upcoming (JWST) NASA IR/Submm astrophysics missions, as well as from ground-based telescopes.

A New Maraging Stainless Steel with Excellent Strength–Toughness–Corrosion Synergy

PubMed Central

Tian, Jialong; Wang, Wei; Babar Shahzad, M.; Yan, Wei; Shan, Yiyin; Jiang, Zhouhua; Yang, Ke

2017-01-01

A new maraging stainless steel with superior strength–toughness–corrosion synergy has been developed based on an innovative concept of alloy design. The high strength–toughness combination is achieved by forming dispersive nano-sized intermetallic compounds in the soft lath martensitic matrix with a slight amount of residual austenite. The good corrosion resistance is guaranteed by exactly controlling the Co content based on understanding the synergistic effect between Co and Cr. The fine structure characteristics of two dominant strengthening precipitations including Ni3Ti and Mo-rich phases were finely characterized associated with transmission electron microscope (TEM) and atom probe tomography (APT) analyses. The relationship among microstructure, strength and toughness is discussed. The precipitation mechanism of different precipitates in the new maraging stainless steel is revealed based on the APT analysis. PMID:29125550

Determination of the fine structure constant using helium fine structure.

PubMed

Smiciklas, Marc; Shiner, David

2010-09-17

We measure 31,908,131.25(30) kHz for the 2(3)}P J=0 to 2 fine structure interval in helium. The difference between this and theory to order mα7 (20 Hz numerical uncertainty) implies 0.22(30) kHz for uncalculated terms. The measurement is performed by using atomic beam and electro-optic laser techniques. Various checks include a 3He 2{3}S hyperfine measurement. We can obtain an independent value for the fine structure constant α with a 5 ppb experimental uncertainty. However, dominant mα8 terms (potentially 1.2 kHz) limit the overall uncertainty to a less competitive 20 ppb in α.

g-Factor of heavy ions: a new access to the fine structure constant.

PubMed

Shabaev, V M; Glazov, D A; Oreshkina, N S; Volotka, A V; Plunien, G; Kluge, H-J; Quint, W

2006-06-30

A possibility for a determination of the fine structure constant in experiments on the bound-electron g-factor is examined. It is found that studying a specific difference of the g-factors of B- and H-like ions of the same spinless isotope in the Pb region to the currently accessible experimental accuracy of 7 x 10(-10) would lead to a determination of the fine structure constant to an accuracy which is better than that of the currently accepted value. Further improvements of the experimental and theoretical accuracy could provide a value of the fine structure constant which is several times more precise than the currently accepted one.

Probing the influence of the center atom coordination structure in iron phthalocyanine multi-walled carbon nanotube-based oxygen reduction reaction catalysts by X-ray absorption fine structure spectroscopy

NASA Astrophysics Data System (ADS)

Peng, Yingxiang; Li, Zhipan; Xia, Dingguo; Zheng, Lirong; Liao, Yi; Li, Kai; Zuo, Xia

2015-09-01

Three different pentacoordinate iron phthalocyanine (FePc) electrocatalysts with an axial ligand (pyridyl group, Py) anchored to multi-walled carbon nanotubes (MWCNTs) are prepared by a microwave method as high performance composite electrocatalysts (FePc-Py/MWCNTs) for the oxygen reduction reaction (ORR). For comparison, tetracoordinate FePc electrocatalysts without an axial ligand anchored to MWCNTs (FePc/MWCNTs) are assembled in the same way. Ultraviolet-visible spectrophotometry (UV-Vis), Raman spectroscopy (RS), and high-resolution transmission electron microscopy (HRTEM) are used to characterize the obtained electrocatalysts. The electrocatalytic activity of the samples is measured by linear sweep voltammetry (LSV), and the onset potential of all of the FePc-Py/MWCNTs electrocatalysts is found to be more positive than that of their FePc/MWCNTs counterparts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy are employed to elucidate the relationship between molecular structure and electrocatalytic activity. XPS indicates that higher concentrations of Fe3+ and pyridine-type nitrogen play critical roles in determining the electrocatalytic ORR activity of the samples. XAFS spectroscopy reveals that the FePc-Py/MWCNTs electrocatalysts have a coordination geometry around Fe that is closer to the square pyramidal structure, a higher concentration of Fe3+, and a smaller phthalocyanine ring radius compared with those of FePc/MWCNTs.

XAFS SPECTROSCOPY ANALYSIS OF SELECTED HAP ELEMENTS IN FINE PM DERIVED FROM COAL COMBUSTION

EPA Science Inventory

X-ray absorption fine structure (XAFS) spectroscopy has been used to investigate the valence states and molecular structures of sulfur (S), chromium (Cr), arsenic (As), and zinc (Zn) in fine particulate matter (PM) separated from coal flyash produced in a realistic combustion sys...

High-Performance Polymer Solar Cells Based on a Wide-Bandgap Polymer Containing Pyrrolo[3,4- f ]benzotriazole-5,7-dione with a Power Conversion Efficiency of 8.63%

DOE PAGES

Lan, Liuyuan; Chen, Zhiming; Hu, Qin; ...

2016-04-25

In article 1600032, an efficient new wide-bandgap polymer based on a novel moiety of pyrrolo[3,4-f]benzotriazole-5,7-dione (TZBI) is developed by Lei Ying, Feng Lui, Thomas P. Russel, Fei Huang, and co-workers. The new chemistry enables fine electronic structure tuning and solution-processed single-junction polymer solar cells provided a remarkable power conversion efficiency of 8.63%. Full electrical and structural characterization reveales that TZBI is a promising building block for the application in highly efficient organic photovoltaics.

Ultrafast exciton fine structure relaxation dynamics in lead chalcogenide nanocrystals.

PubMed

Johnson, Justin C; Gerth, Kathrine A; Song, Qing; Murphy, James E; Nozik, Arthur J; Scholes, Gregory D

2008-05-01

The rates of fine structure relaxation in PbS, PbSe, and PbTe nanocrystals were measured on a femtosecond time scale as a function of temperature with no applied magnetic field by cross-polarized transient grating spectroscopy (CPTG) and circularly polarized pump-probe spectroscopy. The relaxation rates among exciton fine structure states follow trends with nanocrystal composition and size that are consistent with the expected influence of material dependent spin-orbit coupling, confinement enhanced electron-hole exchange interaction, and splitting between L valleys that are degenerate in the bulk. The size dependence of the fine structure relaxation rate is considerably different from what is observed for small CdSe nanocrystals, which appears to result from the unique material properties of the highly confined lead chalcogenide quantum dots. Modeling and qualitative considerations lead to conclusions about the fine structure of the lowest exciton absorption band, which has a potentially significant bearing on photophysical processes that make these materials attractive for practical purposes.

Polygamy and an absence of fine-scale structure in Dendroctonus ponderosae (Hopk.) (Coleoptera: Curcilionidae) confirmed using molecular markers

PubMed Central

Janes, J K; Roe, A D; Rice, A V; Gorrell, J C; Coltman, D W; Langor, D W; Sperling, F A H

2016-01-01

An understanding of mating systems and fine-scale spatial genetic structure is required to effectively manage forest pest species such as Dendroctonus ponderosae (mountain pine beetle). Here we used genome-wide single-nucleotide polymorphisms to assess the fine-scale genetic structure and mating system of D. ponderosae collected from a single stand in Alberta, Canada. Fine-scale spatial genetic structure was absent within the stand and the majority of genetic variation was best explained at the individual level. Relatedness estimates support previous reports of pre-emergence mating. Parentage assignment tests indicate that a polygamous mating system better explains the relationships among individuals within a gallery than the previously reported female monogamous/male polygynous system. Furthermore, there is some evidence to suggest that females may exploit the galleries of other females, at least under epidemic conditions. Our results suggest that current management models are likely to be effective across large geographic areas based on the absence of fine-scale genetic structure. PMID:26286666

Polarization-Dependent Interference of Coherent Scattering from Orthogonal Dipole Moments of a Resonantly Excited Quantum Dot.

PubMed

Chen, Disheng; Lander, Gary R; Solomon, Glenn S; Flagg, Edward B

2017-01-20

Resonant photoluminescence excitation (RPLE) spectra of a neutral InGaAs quantum dot show unconventional line shapes that depend on the detection polarization. We characterize this phenomenon by performing polarization-dependent RPLE measurements and simulating the measured spectra with a three-level quantum model. The spectra are explained by interference between fields coherently scattered from the two fine structure split exciton states, and the measurements enable extraction of the steady-state coherence between the two exciton states.

Solution Structures of Highly Active Molecular Ir Water-Oxidation Catalysts from Density Functional Theory Combined with High-Energy X-ray Scattering and EXAFS Spectroscopy.

PubMed

Yang, Ke R; Matula, Adam J; Kwon, Gihan; Hong, Jiyun; Sheehan, Stafford W; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H; Tiede, David M; Chen, Lin X; Batista, Victor S

2016-05-04

The solution structures of highly active Ir water-oxidation catalysts are elucidated by combining density functional theory, high-energy X-ray scattering (HEXS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. We find that the catalysts are Ir dimers with mono-μ-O cores and terminal anionic ligands, generated in situ through partial oxidation of a common catalyst precursor. The proposed structures are supported by (1)H and (17)O NMR, EPR, resonance Raman and UV-vis spectra, electrophoresis, etc. Our findings are particularly valuable to understand the mechanism of water oxidation by highly reactive Ir catalysts. Importantly, our DFT-EXAFS-HEXS methodology provides a new in situ technique for characterization of active species in catalytic systems.

Synthesis and characterization of novel low density polyethylene-multiwall carbon nanotube porous composites

NASA Astrophysics Data System (ADS)

Rizvi, Reza; Kim, Jae-Kyung; Naguib, Hani

2009-10-01

This study details the synthesis and characterization of novel porous composites of low density polyethylene (PE) and multiwalled carbon nanotubes (MWNT). PE-MWNT composites were prepared by melt blending the components in a twin screw compounder and porous structures were produced by a batch technique using CO2 as the solvent. The composites were characterized for dispersion using scanning electron microscopy and transmission electron microscopy; the results indicate a finely dispersed MWNT phase in PE. Thermal, rheological, electrical and mechanical properties of the composites were characterized and results indicate an electrical and rheological percolation threshold concentration of between 1 and 2 wt% MWNT in PE. Substantial improvements in the mechanical and electrical properties of PE were observed with the addition of 5 wt% MWNT. The porous PE-MWNT composites fabricated in this study were found to be conductive and have potential applications as anti-static materials for electrostatic discharge prevention.

Synthesis and Characterization of SF-PPV-I

NASA Technical Reports Server (NTRS)

Wang, Y.; Fan, Z.; Taft, C.; Sun, S.

2001-01-01

Conjugated electro-active polymers find their potential applications in developing variety inexpensive and flexible shaped electronic and photonic devices, such as photovoltaic or photo/electro light emitting devices. In many of these opto-electronic polymeric materials, certain electron rich donors and electron deficient acceptors are needed in order to fine-tune the electronic or photonic properties of the desired materials and structures. While many donor type of conjugated polymers have been widely studied and developed in the past decades, there are relatively fewer acceptor type of conjugated polymers have been developed. Key acceptor type conjugated polymers developed so far include C60 and CN-PPV, and each has its limitations. Due to the complexity and diversity of variety future electronic materials and structural needs, alternative and synthetically amenable acceptor conjugated polymers need to be developed. In this paper, we present the synthesis and characterization of a new acceptor conjugated polymer, a sulfone derivatized polyphenylenevinylene "SF-PPV".

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

Liu, Zhi-jie; Dai, Le-yang; Yang, De-zheng

Highlights: • A novel and high efficiency synthesizing AlN powders method combining mechanical ball milling and DBDP has been developed. • The particle size, the crystallite size, the lattice distortion, the morphology of Al{sub 2}O{sub 3} powders, and the AlN conversion rate are investigated and compared under the ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP. • The ball milled Al{sub 2}O{sub 3} powders with DBDP have small spherical structure morphology with very fine particles size and high specific surface area, which result in a higher chemical efficiency and a higher AlN conversion rate at lower thermalmore » temperature. - Abstract: In this paper, aluminum nitride (AlN) powers have been produced with a novel and high efficiency method by thermal annealing at 1100–1600 °C of alumina (Al{sub 2}O{sub 3}) powders which were previously ball milled for various time up to 40 h with and without the assistant of dielectric barrier discharge plasma (DBDP). The ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP and the corresponding synthesized AlN powers are characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. From the characteristics of the ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP, it can be seen that the ball milled Al{sub 2}O{sub 3} powders with DBDP have small spherical structure morphology with very fine particles size and high specific surface area, which result in a higher chemical efficiency and a higher AlN conversion rate at lower thermal temperature. Meanwhile, the synthesized AlN powders can be known as hexagonal AlN with fine crystal morphology and irregular lump-like structure, and have uniform distribution with the average particle size of about between 500 nm and 1000 nm. This provides an important method for fabricating ultra fine powders and synthesizing nitrogen compounds.« less

Nanoclusters of α-Fe naturally formed in twinned martensite after martensitic transformation

NASA Astrophysics Data System (ADS)

Liu, X.; Ping, D. H.; Xiang, H. P.; Lu, X.; Shen, J.

2018-05-01

Various Fe-C binary alloys with the carbon content from 0.05 to 2.0 (wt. %) have been prepared and water-quenched at austenitizing temperatures. The fine structure of the twinned martensite in the quenched samples has been investigated by means of transmission electron microscopy (TEM) in order to understand the initial products during the formation of the martensite structure. In the twinned structure (body-centered-cubic {112}⟨111⟩-type twin), TEM dark field observations have revealed that both matrix and twinned crystal regions are fully composed of ultra-fine particles (α-Fe nano-crystallites). The particles tend to have the same preferred direction (or texture) in the twinned martensite and the size is almost the same (1-2 nm). The ultra-fine particle structure has been commonly observed regardless of the carbon content; however, such a fine particle structure has been observed only in the martensite with the twinning structure. After in-situ TEM heating, recrystallization occurred and the fine particles merged into larger α-Fe grains; at the same time, the twinned relationship also disappeared.

Advances in Ultra High Temperature Ceramics for Hot Structures

NASA Astrophysics Data System (ADS)

Scatteia, Luigi; Monteverde, Federico; Alfano, Davide; Cantoni, Stefania

The objective of this paper is to describe the current state of the art of the research on Ultra High Temperature Ceramic materials with particular reference to their space applications, and also to report on the activities performed on UHTC in the past decade by the Italian Aerospace Research Centre in the specific technological field of structural thermal protection systems. Within several internal research project, various UHTC composition, mainly based upon Zirconium Diboride and Hafnium Diboride with added secondary phases and sintering aid were examined characterized in their mechanical properties and oxidation resistance. Two main composition were selected as the most promising for hot structure manufacturing: these materials were extensively characterized in order to obtain a comprehensive database of properties to feed the thermomechanical design of prototype hot structures. Technological demonstrators were manufactured by hot pressing followed by further fine machining with Electrical Discharge methods, and then tested at high temperature for long times in a plasma torch facility. The main outstanding results obtained are discussed in this paper. Future outlooks related to the UHTC technology and its further development are also provided.

Microstructure, Morphology, and Nanomechanical Properties Near Fine Holes Produced by Electro-Discharge Machining

NASA Astrophysics Data System (ADS)

Blau, P. J.; Howe, J. Y.; Coffey, D. W.; Trejo, R. M.; Kenik, E. D.; Jolly, B. C.; Yang, N.

2012-08-01

Fine holes in metal alloys are employed for many important technological purposes, including cooling and the precise atomization of liquids. For example, they play an important role in the metering and delivery of fuel to the combustion chambers in energy-efficient, low-emission diesel engines. Electro-discharge machining (EDM) is one process employed to produce such holes. Since the hole shape and bore morphology can affect fluid flow, and holes also represent structural discontinuities in the tips of the spray nozzles, it is important to understand the microstructures adjacent to these holes, the features of the hole walls, and the nanomechanical properties of the material that was in some manner altered by the EDM hole-making process. Several techniques were used to characterize the structure and properties of spray-holes in a commercial injector nozzle. These include scanning electron microscopy, cross sectioning and metallographic etching, bore surface roughness measurements by optical interferometry, scanning electron microscopy, and transmission electron microscopy of recast EDM layers extracted with the help of a focused ion beam.

Optimized ultra-thin manganin alloy passivated fine-pitch damascene compatible bump-less Cu-Cu bonding at sub 200 °C for three-dimensional Integration applications

NASA Astrophysics Data System (ADS)

Panigrahi, Asisa Kumar; Hemanth Kumar, C.; Bonam, Satish; Ghosh, Tamal; Rama Krishna Vanjari, Siva; Govind Singh, Shiv

2018-02-01

Enhanced Cu diffusion, Cu surface passivation, and smooth surface at the bonding interface are the key essentials for high quality Cu-Cu bonding. Previously, we have demonstrated optimized 3 nm thin Manganin metal-alloy passivation from oxidation and also helps to reduce the surface roughness to about 0.8 nm which substantially led to high quality Cu-Cu bonding. In this paper, we demonstrated an ultra fine-pitch (<25 µm) Cu-Cu bonding using an optimized Manganin metal-alloy passivation. This engineered surface passivation approach led to high quality bonding at sub 200 °C temperature and 0.4 MPa. Very low specific contact resistance of 1.4 × 10-7 Ω cm2 and the defect free bonded interface is clear indication of high quality bonding for future multilayer integrations. Furthermore, electrical characterization of the bonded structure was performed under various robust conditions as per International Technology Roadmap for Semiconductors (ITRS Roadmap) in order to satisfy the stability of the bonded structure.

Characterization of Fine Particulate Matter (PM) and Secondary PM Precursor Gases in the Mexico City Metropolitan Area

DOE R&D Accomplishments Database

Molina, Luisa T.; Volkamer, Rainer; de Foy, Benjamin; Lei, Wenfang; Zavala, Miguel; Velasco, Erik; Molina; Mario J.

2008-10-31

This project was one of three collaborating grants funded by DOE/ASP to characterize the fine particulate matter (PM) and secondary PM precursors in the Mexico City Metropolitan Area (MCMA) during the MILAGRO Campaign. The overall effort of MCMA-2006, one of the four components, focused on i) examination of the primary emissions of fine particles and precursor gases leading to photochemical production of atmospheric oxidants and secondary aerosol particles; ii) measurement and analysis of secondary oxidants and secondary fine PM production, with particular emphasis on secondary organic aerosol (SOA), and iii) evaluation of the photochemical and meteorological processes characteristic of the Mexico City Basin. The collaborative teams pursued the goals through three main tasks: i) analyses of fine PM and secondary PM precursor gaseous species data taken during the MCMA-2002/2003 campaigns and preparation of publications; ii) planning of the MILAGRO Campaign and deployment of the instrument around the MCMA; and iii) analysis of MCMA-2006 data and publication preparation.

Hubble Space Telescope images and follow-up spectroscopy of the Orion nebula

NASA Technical Reports Server (NTRS)

O'Dell, C. R.; Wen, Zheng; Hester, J. J.

1991-01-01

Recently published HST images of the Orion nebula reveal elephant-trunk structures, an apparent jet of material, and fine-scale structure in the Herbig-Haro object HH2, which is located at the base of an elephant trunk. High-resolution spectroscopy shows that the apparent jet is actually an ionization front seen edge-on. HH2 shows a complex structure in the several stages of ionization observed. There seem to be two velocity systems characterized by a bright central region and an accompanying shell-like emission. These two systems are most likely to be the result of a bow shock and corresponding Mach disk formed from the interaction of a collimated jet and the ambient gas of the nebula.

The mechanical properties of austenite stainless steel 304 after structural deformation through cold work

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

Mubarok, Naila; Manaf, Azwar, E-mail: azwar@ui.ac.id; Notonegoro, Hamdan Akbar

The 304 stainless steel (SS) type is widely used in oil and gas operations due to its excellent corrosion resistance. However, the presence of the fine sand particles and H{sub 2}S gas contained in crude oil could lead the erosion and abrasion in steel. In this study, cold rolled treatments were conducted to the 304 SS in order to increase the wear resistance of the steel. The cold work has resulted in thickness reduction to 20%, 40% and 60% of the original. Various microstructural characterizations were used to analyze the effect of deformation. The hardness characterization showed that the initialmore » hardness value increased from 145 HVC to 395 HVC as the level of deformation increase. Further, the wear resistance increased with the deformation rate from 0% to 40% and subsequently decreased from 40% to 60% deformation rate. Microstructural characterization shows that the boundary change to coincide by 56 µm, 49 µm, 45 µm, and 43 µm width and the grain go to flatten and being folded like needles. The effect of deformation on the grain morphology and structure was also studied by optical metallography and X-Ray Diffraction. It is shown that the deformation by means of a cold rolled process has transformed the austenite structure into martensitic structure.« less

Probing the Detailed Seismic Velocity Structure of Subduction Zones Using Advanced Seismic Tomography Methods

NASA Astrophysics Data System (ADS)

Zhang, H.; Thurber, C. H.

2005-12-01

Subduction zones are one of the most important components of the Earth's plate tectonic system. Knowing the detailed seismic velocity structure within and around subducting slabs is vital to understand the constitution of the slab, the cause of intermediate depth earthquakes inside the slab, the fluid distribution and recycling, and tremor occurrence [Hacker et al., 2001; Obara, 2002].Thanks to the ability of double-difference tomography [Zhang and Thurber, 2003] to resolve the fine-scale structure near the source region and the favorable seismicity distribution inside many subducting slabs, it is now possible to characterize the fine details of the velocity structure and earthquake locations inside the slab, as shown in the study of the Japan subduction zone [Zhang et al., 2004]. We further develop the double-difference tomography method in two aspects: the first improvement is to use an adaptive inversion mesh rather than a regular inversion grid and the second improvement is to determine a reliable Vp/Vs structure using various strategies rather than directly from Vp and Vs [see our abstract ``Strategies to solve for a better Vp/Vs model using P and S arrival time'' at Session T29]. The adaptive mesh seismic tomography method is based on tetrahedral diagrams and can automatically adjust the inversion mesh according to the ray distribution so that the inversion mesh nodes are denser where there are more rays and vice versa [Zhang and Thurber, 2005]. As a result, the number of inversion mesh nodes is greatly reduced compared to a regular inversion grid with comparable spatial resolution, and the tomographic system is more stable and better conditioned. This improvement is quite valuable for characterizing the fine structure of the subduction zone considering the highly uneven distribution of earthquakes within and around the subducting slab. The second improvement, to determine a reliable Vp/Vs model, lies in jointly inverting Vp, Vs, and Vp/Vs using P, S, and S-P times in a manner similar to double-difference tomography. Obtaining a reliable Vp/Vs model of the subduction zone is more helpful for understanding its mechanical and petrologic properties. Our applications of the original version of double-difference tomography to several subduction zones beneath northern Honshu, Japan, the Wellington region, New Zealand, and Alaska, United States, have shown evident velocity variations within and around the subducting slab, which likely is evidence of dehydration reactions of various hydrous minerals that are hypothesized to be responsible for intermediate depth earthquakes. We will show the new velocity models for these subduction zones by applying our advanced tomographic methods.

Genome-wide SNPs lead to strong signals of geographic structure and relatedness patterns in the major arbovirus vector, Aedes aegypti.

PubMed

Rašić, Gordana; Filipović, Igor; Weeks, Andrew R; Hoffmann, Ary A

2014-04-11

Genetic markers are widely used to understand the biology and population dynamics of disease vectors, but often markers are limited in the resolution they provide. In particular, the delineation of population structure, fine scale movement and patterns of relatedness are often obscured unless numerous markers are available. To address this issue in the major arbovirus vector, the yellow fever mosquito (Aedes aegypti), we used double digest Restriction-site Associated DNA (ddRAD) sequencing for the discovery of genome-wide single nucleotide polymorphisms (SNPs). We aimed to characterize the new SNP set and to test the resolution against previously described microsatellite markers in detecting broad and fine-scale genetic patterns in Ae. aegypti. We developed bioinformatics tools that support the customization of restriction enzyme-based protocols for SNP discovery. We showed that our approach for RAD library construction achieves unbiased genome representation that reflects true evolutionary processes. In Ae. aegypti samples from three continents we identified more than 18,000 putative SNPs. They were widely distributed across the three Ae. aegypti chromosomes, with 47.9% found in intergenic regions and 17.8% in exons of over 2,300 genes. Pattern of their imputed effects in ORFs and UTRs were consistent with those found in a recent transcriptome study. We demonstrated that individual mosquitoes from Indonesia, Australia, Vietnam and Brazil can be assigned with a very high degree of confidence to their region of origin using a large SNP panel. We also showed that familial relatedness of samples from a 0.4 km2 area could be confidently established with a subset of SNPs. Using a cost-effective customized RAD sequencing approach supported by our bioinformatics tools, we characterized over 18,000 SNPs in field samples of the dengue fever mosquito Ae. aegypti. The variants were annotated and positioned onto the three Ae. aegypti chromosomes. The new SNP set provided much greater resolution in detecting population structure and estimating fine-scale relatedness than a set of polymorphic microsatellites. RAD-based markers demonstrate great potential to advance our understanding of mosquito population processes, critical for implementing new control measures against this major disease vector.

An Action-Based Fine-Grained Access Control Mechanism for Structured Documents and Its Application

PubMed Central

Su, Mang; Li, Fenghua; Tang, Zhi; Yu, Yinyan; Zhou, Bo

2014-01-01

This paper presents an action-based fine-grained access control mechanism for structured documents. Firstly, we define a describing model for structured documents and analyze the application scenarios. The describing model could support the permission management on chapters, pages, sections, words, and pictures of structured documents. Secondly, based on the action-based access control (ABAC) model, we propose a fine-grained control protocol for structured documents by introducing temporal state and environmental state. The protocol covering different stages from document creation, to permission specification and usage control are given by using the Z-notation. Finally, we give the implementation of our mechanism and make the comparisons between the existing methods and our mechanism. The result shows that our mechanism could provide the better solution of fine-grained access control for structured documents in complicated networks. Moreover, it is more flexible and practical. PMID:25136651

An action-based fine-grained access control mechanism for structured documents and its application.

PubMed

Su, Mang; Li, Fenghua; Tang, Zhi; Yu, Yinyan; Zhou, Bo

2014-01-01

This paper presents an action-based fine-grained access control mechanism for structured documents. Firstly, we define a describing model for structured documents and analyze the application scenarios. The describing model could support the permission management on chapters, pages, sections, words, and pictures of structured documents. Secondly, based on the action-based access control (ABAC) model, we propose a fine-grained control protocol for structured documents by introducing temporal state and environmental state. The protocol covering different stages from document creation, to permission specification and usage control are given by using the Z-notation. Finally, we give the implementation of our mechanism and make the comparisons between the existing methods and our mechanism. The result shows that our mechanism could provide the better solution of fine-grained access control for structured documents in complicated networks. Moreover, it is more flexible and practical.

InAs Band-Edge Exciton Fine Structure

DTIC Science & Technology

2015-07-29

Chapter 1 InAs Band-Edge Exciton Fine Structure 1.1 Contributions This work was carried out in collaboration with Oscar Sandoval, a summer student at...diffusion,1,2 charg- ing,2,3 and excitonic fine structure.1,3–9 While spectral diffusion and charging are most likely photoinduced effects and thus can be...unavoidable. A complete understanding of the excitonic 1 Distribution A: Public Release energy landscape enables us to determine dephasing rates

Atomic sulfur: Frequency measurement of the J = 0 left arrow 1 fine-structure transition at 56.3 microns by laser magnetic resonance

NASA Technical Reports Server (NTRS)

Brown, John M.; Evenson, Kenneth M.; Zink, Lyndon R.

1994-01-01

The J = 0 left arrow 1 fine-structure transition in atomic sulfur (S I) in its ground (3)P state has been detected in the laboratory by far-infrared laser magnetic resonance. The fine-structure interval has been measured accurately as 5,322,492.9 +/- 2.8 MHz which corresponds to a wavelength of 56.325572 +/- 0.000030 micrometers.

Effects of fluidization of the host sediment on peperite textures: A field example from the Cretaceous Buan Volcanics, SW Korea

NASA Astrophysics Data System (ADS)

Gihm, Yong Sik; Kwon, Chang Woo

2017-04-01

In the Cretaceous Buan Volcanics (SW Korea), blocky and fluidal peperites are hosted in a massive pumiceous lapilli tuff intruded by intermediate dikes. Blocky peperites, the most abundant species, are characterized by polyhedral or platy juvenile clasts and a jigsaw-crack texture. Fluidal peperites occur only along dike margins, where the host sediments are composed of well sorted, fine to very fine ash (fine-grained zone), and are characterized by fluidal or globular juvenile clasts with irregular or ragged margins. The fine-grained zone is interpreted to form by grain size segregation caused by upward moving pore water (fluidization) that has resulted from heat transfer from intruding magma toward waterlogged host sediments during intrusion. With the release of pore water and the selective entrainment of fine-grained ash, fine-grained zones formed within the host sediments. Subsequent interactions between the fine-grained zone and the intruding magma resulted in ductile deformation of the magma before fragmentation, which generated fluidal peperites. Outside the fine-grained zone, intruding magma fragmented in a brittle manner because of the relative deficiency of both pore water and fine-grained ash, resulting in the formation of blocky peperites. The results of this study suggest that redistribution of constituent particles (ash) and interstitial fluids during fluidization resulted in heterogeneous physical conditions of the host sediments, which influenced peperite-forming processes, as reflected by the different peperite textures.

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

Gustavson, T.C.; Holliday, V.T.

Eolian sediments have accumulated as non-glacigenic loess and thin sand sheets on the Central and Southern High Plains grasslands of Texas and new mexico since the late Miocene. Locally as much as 110 m of eolian sediments with numerous paleosols are preserved in the Quaternary Blackwater Draw formation and the upper part of the Miocene-Pleiocene Ogallala formation. These sediments and paleosols, which cover more than 130,000 km{sup 2}, are similar to recent surface sediments and soils and record a long period of episodic eolian transport and sedimentation, and pedogenesis on a stable low-relief grass-covered landscape. Eolian sections, which comprise themore » fine sand to coarse silt lithofacies of the Ogallala formation, and the very fine to fine sand and sandy mud lithofacies of the Blackwater Draw formation, generally lack primary sedimentary structures. Grain size of Ogallala sediments decreases from west to east and grain size of Blackwater Draw sediments decreases from southwest to northeast. Soil horizonation is well developed in most sections, and buried calcic and argillic horizons are common. Calcic horizons are characterized by sharply increased CaCO{sub 3} content in the form of filaments, nodules, and petrocalcic horizons (calcretes). Argillic horizons are characterized by increased illuvial clay, pedogenic structure, and darker reddish hues. Rhizocretions are common locally. Open root tubules, which are typically less than 1 mm in diameter and characteristic of small plants like grasses, are present in all Ogallala and Blackwater Draw eolian sediments. Paleosols preserved in eolian sediments of the High Plains reflect periods of sedimentation followed by episodes of landscape stability and pedogenesis, and negligible sedimentation. Episodes of sedimentation and soil development likely resulted from cyclic decreases and increases in available moisture and vegetative cover. Eolian sediments were eroded and transported eastward during dry periods when vegetation was sparse in source areas, such as the western High Plains and the Pecos Valley. During humid periods more abundant vegetation probably protected source areas from deflation, and resulted in landscape stability across the High Plains.« less

Fine reservoir structure modeling based upon 3D visualized stratigraphic correlation between horizontal wells: methodology and its application

NASA Astrophysics Data System (ADS)

Chenghua, Ou; Chaochun, Li; Siyuan, Huang; Sheng, James J.; Yuan, Xu

2017-12-01

As the platform-based horizontal well production mode has been widely applied in petroleum industry, building a reliable fine reservoir structure model by using horizontal well stratigraphic correlation has become very important. Horizontal wells usually extend between the upper and bottom boundaries of the target formation, with limited penetration points. Using these limited penetration points to conduct well deviation correction means the formation depth information obtained is not accurate, which makes it hard to build a fine structure model. In order to solve this problem, a method of fine reservoir structure modeling, based on 3D visualized stratigraphic correlation among horizontal wells, is proposed. This method can increase the accuracy when estimating the depth of the penetration points, and can also effectively predict the top and bottom interfaces in the horizontal penetrating section. Moreover, this method will greatly increase not only the number of points of depth data available, but also the accuracy of these data, which achieves the goal of building a reliable fine reservoir structure model by using the stratigraphic correlation among horizontal wells. Using this method, four 3D fine structure layer models have been successfully built of a specimen shale gas field with platform-based horizontal well production mode. The shale gas field is located to the east of Sichuan Basin, China; the successful application of the method has proven its feasibility and reliability.

Morphology, stability, and X-ray absorption spectroscopic study of iron oxide (Hematite) nanoparticles prepared by micelle nanolithography

NASA Astrophysics Data System (ADS)

Bera, Anupam; Bhattacharya, Atanu; Tiwari, N.; Jha, S. N.; Bhattacharyya, D.

2018-03-01

Currently, considerable effort is being made towards synthesis and characterization of iron oxide nanoparticles. In this article, we report on the preparation and characterization of iron oxide nanoparticle (NP) arrays supported on natively oxidized Si(100) surface. The NPs are synthesized by reverse micelle nanolithography technique and are then deposited onto natively oxidized Si(100) surface via spin-coating. Plasma oxidation followed by high temperature annealing results in a unimodal size distribution of pseudohexagonally-ordered array of iron oxide NPs (with ∼14 nm mean diameter and ∼5 nm mean height). High temperature annealing does not fragment the NPs. Particles are sinter-resistant: the unimodal arrays are robust with respect to thermal treatment. X-ray absorption spectroscopy (XAS), including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS), reveals that structure of the iron oxide particle resembles closely the hematite α-Fe2O3 structure. Furthermore, with the help of EXAFS spectra, we eliminate the possibility of γ-Fe2O3, Fe3O4, FeO and FeO(OH) structures for the NPs.

A new comprehensive approach to characterizing carbonaceous aerosol with an application to wintertime Fresno, California PM2.5

USGS Publications Warehouse

Herckes, P.; Leenheer, J.A.; Collett, J.L.

2007-01-01

Fine particulate matter (PM2.5) samples were collected during a three week winter period in Fresno (CA). A composite sample was characterized by isolating several distinct fractions and characterizing them by infrared and nuclear magnetic resonance (NMR) spectroscopy. More than 80% of the organic matter in the aerosol samples was recovered and characterized. Only 35% of the organic matter was water soluble with another third soluble in dichloromethane and the remainder insoluble. Within the isolated water soluble material, hydrophobic acid and hydrophilic acids plus neutrals fractions contained the largest amounts of carbon. The hydrophobic acids fraction appears to contain significant amounts of lignin type structures, spectra of the hydrophilic acids plus neutrals fraction are indicative of carbohydrates and secondary organic material. The dichloromethane soluble fraction contains a variety of organic compound families typical of many previous studies of organic aerosol speciation, including alkanes, alkanols, alkanals and alkanoic acids. Finally the water and solvent insoluble fraction exhibits a strong aromaticity as one would expect from black or elemental carbon like material; however, these spectra also show a substantial amount of aliphaticity consistent with linear side chains on the aromatic structures.

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

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

The impact of cochlear fine structure on hearing thresholds and DPOAE levels

NASA Astrophysics Data System (ADS)

Lee, Jungmee; Long, Glenis; Talmadge, Carrick L.

2004-05-01

Although otoacoustic emissions (OAE) are used as clinical and research tools, the correlation between OAE behavioral estimates of hearing status is not large. In normal-hearing individuals, the level of OAEs can vary as much as 30 dB when the frequency is changed less than 5%. These pseudoperiodic variations of OAE level with frequency are known as fine structure. Hearing thresholds measured with high-frequency resolution reveals a similar (up to 15 dB) fine structure. We examine the impact of OAE and threshold fine structures on the prediction of auditory thresholds from OAE levels. Distortion product otoacoustic emissions (DPOAEs) were measured with sweeping primary tones. Psychoacoustic detection thresholds were measured using pure tones, sweep tones, FM tones, and narrow-band noise. Sweep DPOAE and narrow-band threshold estimates provide estimates that are less influenced by cochlear fine structure and should lead to a higher correlation between OAE levels and psychoacoustic thresholds. [Research supported by PSC CUNY, NIDCD, National Institute on Disability and Rehabilitation Research in U.S. Department of Education, and The Ministry of Education in Korea.

CONSTRAINTS ON SPATIAL VARIATIONS IN THE FINE-STRUCTURE CONSTANT FROM PLANCK

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

O'Bryan, Jon; Smidt, Joseph; De Bernardis, Francesco

2015-01-01

We use the cosmic microwave background (CMB) anisotropy data from Planck to constrain the spatial fluctuations of the fine-structure constant α at a redshift of 1100. We use a quadratic estimator to measure the four-point correlation function of the CMB temperature anisotropies and extract the angular power spectrum fine-structure constant spatial variations projected along the line of sight at the last scattering surface. At tens of degree angular scales and above, we constrain the fractional rms fluctuations of the fine-structure constant to be (δα/α){sub rms} < 3.4 × 10{sup –3} at the 68% confidence level. We find no evidence formore » a spatially varying α at a redshift of 10{sup 3}.« less

Fine structural dependence of ultraviolet reflections in the King Penguin beak horn.

PubMed

Dresp, Birgitta; Langley, Keith

2006-03-01

The visual perception of many birds extends into the near-ultraviolet (UV) spectrum and ultraviolet is used by some to communicate. The beak horn of the King Penguin (Aptenodytes patagonicus) intensely reflects in the ultraviolet and this appears to be implicated in partner choice. In a preliminary study, we recently demonstrated that this ultraviolet reflectance has a structural basis, resulting from crystal-like photonic structures, capable of reflecting in the near-UV. The present study attempted to define the origin of the photonic elements that produce the UV reflectance and to better understand how the UV signal is optimized by their fine structure. Using light and electron microscopic analysis combined with new spectrophotometric data, we describe here in detail the fine structure of the entire King Penguin beak horn in addition to that of its photonic crystals. The data obtained reveal a one-dimensional structural periodicity within this tissue and demonstrate a direct relationship between its fine structure and its function. In addition, they suggest how the photonic structures are produced and how they are stabilized. The measured lattice dimensions of the photonic crystals, together with morphological data on its composition, permit predictions of the wavelength of reflected light. These correlate well with experimentally observed values. The way the UV signal is optimized by the fine structure of the beak tissue is discussed with regard to its putative biological role.

Integration of ALOS/PALSAR backscatter with a LiDAR-derived canopy height map to quantify forest fragmentation

NASA Astrophysics Data System (ADS)

Pinto, N.; Dubayah, R.; Simard, M.; Fatoyinbo, T. E.

2011-12-01

Habitat loss is the main predictor of species extinctions and must be characterized in high-biodiversity ecosystems where land cover change is pervasive. Forests' ability to support viable animal populations is typically modeled as a function of the presence of linkages or corridors, and quantified with fragmentation metrics. In this scenario, small forest patches and linear (e.g. riparian) zones can act as keystone structures. Fine-resolution, all-weather Synthetic Aperture Radar (SAR) data from ALOS/PALSAR is well-suited to resolve forest fragments in tropical sites. This study summarizes a technique for integrating fragmentation metrics from ALOS/PALSAR with vertical structure data from ICESat/GLAS to produce fine-resolution (30 m) forest habitat metrics that capture both local quality (canopy height) as well as spatial context and multi-scale connectivity. We illustrate our approach with backscatter images acquired over the Brazilian Atlantic Forest, a biodiversity hotspot. ALOS/PALSAR 1.1 images acquired over the dry season were calibrated to calculate gamma naught and map forest cover via tresholding. We employ network algorithms to locate dispersal bottlenecks between conservation units. The location of keystone structures is compared against a model that uses coarse (500m) percent tree cover as an input.

Dynamics of brain activity in motor and frontal cortical areas during music listening: a magnetoencephalographic study.

PubMed

Popescu, Mihai; Otsuka, Asuka; Ioannides, Andreas A

2004-04-01

There are formidable problems in studying how 'real' music engages the brain over wide ranges of temporal scales extending from milliseconds to a lifetime. In this work, we recorded the magnetoencephalographic signal while subjects listened to music as it unfolded over long periods of time (seconds), and we developed and applied methods to correlate the time course of the regional brain activations with the dynamic aspects of the musical sound. We showed that frontal areas generally respond with slow time constants to the music, reflecting their more integrative mode; motor-related areas showed transient-mode responses to fine temporal scale structures of the sound. The study combined novel analysis techniques designed to capture and quantify fine temporal sequencing from the authentic musical piece (characterized by a clearly defined rhythm and melodic structure) with the extraction of relevant features from the dynamics of the regional brain activations. The results demonstrated that activity in motor-related structures, specifically in lateral premotor areas, supplementary motor areas, and somatomotor areas, correlated with measures of rhythmicity derived from the music. These correlations showed distinct laterality depending on how the musical performance deviated from the strict tempo of the music score, that is, depending on the musical expression.

[CuCl(n)](2-n) ion-pair species in 1-ethyl-3-methylimidazolium chloride ionic liquid-water mixtures: ultraviolet-visible, X-ray absorption fine structure, and density functional theory characterization.

PubMed

Li, Guosheng; Camaioni, Donald M; Amonette, James E; Zhang, Z Conrad; Johnson, Timothy J; Fulton, John L

2010-10-07

We studied the coordination environment about Cu(II) in a pure ionic liquid, 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl), and in binary mixtures of this compound with water across the entire range of compositions, using a combination of X-ray absorption fine structure (XAFS), ultraviolet-visible (UV-vis) spectroscopy, and electronic structure calculations. Our results show a series of stages in the ion pairing of the divalent cation, Cu(II), including the contact ion pairing of Cu(2+) with multiple Cl(-) ligands to form various CuCl(n)((2-n)) polyanions, as well as the subsequent solvation and ion pairing of the polychlorometallate anion with the EMIM(+) cation. Ion-pair formation is strongly promoted in [EMIM]Cl by the low dielectric constant and by the extensive breakdown of the water hydrogen-bond network in [EMIM]Cl-water mixtures. The CuCl(4)(2-) species dominates in the [EMIM]Cl solvent, and calculations along with spectroscopy show that its geometry distorts to C(2) symmetry compared to D(2d) in the gas phase. These results are important in understanding catalysis and separation processes involving transition metals in ionic liquid systems.

Microstructure and Microhardness of 17-4PH Deposited with Co-based Alloy Hardfacing Coating

NASA Astrophysics Data System (ADS)

Deng, D. W.; Zhang, C. P.; Chen, R.; Xia, H. F.

Hardfacing is widely used to improve the performance of components exposed to severe service conditions. In this paper, the surface modification was evaluated for precipitation hardening martensitic stainless steel 17-4PH deposited with Co-based alloy stellite12 by the plasma-transferred arc welding (PTAW). The microstructure and microhardness of coating and heat affected zone(HAZ) of base metal were characterized by optical microscope (OM), scanning electron scanning microscope (SEM), X-ray diffractometer and hardness tester. The results show that the interface between weld metal and base metal is favorable without pore and crack, at the same time elements diffusion is observed in the fusion area. However, as the distance from the interface increases, HAZ comprises three different microstructural zones, namely, zones of coarse overheated structures, quenching martensite and martensite, ferrite. The microhardness decreases gradually from the HAZ near interface to the base metal, except the zone of coarse overheated structures. The microhardness of the coating improves a lot and fluctuates in a definitive range, and microstructural gradient is observed including the fusion area (the planar region and the bulky dendrite in a direction perpendicular to the weld interface), the transition zone (the dendrite in a multi-direction way) and the fine grain zone near the surface in the coating (fine equiaxial structure).

Atmospheric fate and transport of fine volcanic ash: Does particle shape matter?

NASA Astrophysics Data System (ADS)

White, C. M.; Allard, M. P.; Klewicki, J.; Proussevitch, A. A.; Mulukutla, G.; Genareau, K.; Sahagian, D. L.

2013-12-01

Volcanic ash presents hazards to infrastructure, agriculture, and human and animal health. In particular, given the economic importance of intercontinental aviation, understanding how long ash is suspended in the atmosphere, and how far it is transported has taken on greater importance. Airborne ash abrades the exteriors of aircraft, enters modern jet engines and melts while coating interior engine parts causing damage and potential failure. The time fine ash stays in the atmosphere depends on its terminal velocity. Existing models of ash terminal velocities are based on smooth, quasi-spherical particles characterized by Stokes velocity. Ash particles, however, violate the various assumptions upon which Stokes flow and associated models are based. Ash particles are non-spherical and can have complex surface and internal structure. This suggests that particle shape may be one reason that models fail to accurately predict removal rates of fine particles from volcanic ash clouds. The present research seeks to better parameterize predictive models for ash particle terminal velocities, diffusivity, and dispersion in the atmospheric boundary layer. The fundamental hypothesis being tested is that particle shape irreducibly impacts the fate and transport properties of fine volcanic ash. Pilot studies, incorporating modeling and experiments, are being conducted to test this hypothesis. Specifically, a statistical model has been developed that can account for actual volcanic ash size distributions, complex ash particle geometry, and geometry variability. Experimental results are used to systematically validate and improve the model. The experiments are being conducted at the Flow Physics Facility (FPF) at UNH. Terminal velocities and dispersion properties of fine ash are characterized using still air drop experiments in an unconstrained open space using a homogenized mix of source particles. Dispersion and sedimentation dynamics are quantified using particle image velocimetry (PIV). Scanning Electron Microscopy (SEM) of ash particles collected in localized deposition areas is used to correlate the PIV results to particle shape. In addition, controlled wind tunnel experiments are used to determine particle fate and transport in a turbulent boundary layer for a mixed particle population. Collectively, these studies will provide an improved understanding of the effects of particle shape on sedimentation and dispersion, and foundational data for the predictive modeling of the fate and transport of fine ash particles suspended in the atmosphere.

Spin fine structure of optically excited quantum dot molecules

NASA Astrophysics Data System (ADS)

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

2007-06-01

The interaction between spins in coupled quantum dots is revealed in distinct fine structure patterns in the measured optical spectra of InAs/GaAs double quantum dot molecules containing zero, one, or two excess holes. The fine structure is explained well in terms of a uniquely molecular interplay of spin-exchange interactions, Pauli exclusion, and orbital tunneling. This knowledge is critical for converting quantum dot molecule tunneling into a means of optically coupling not just orbitals but also spins.

Structure and optical properties of silica-supported Ag-Au nanoparticles.

PubMed

Barreca, Davide; Gasparotto, Alberto; Maragno, Cinzia; Tondello, Eugenio; Gialanella, Stefano

2007-07-01

Bimetallic Ag-Au nanoparticles are synthesized by sequential deposition of Au and Ag on amorphous silica by Radio Frequency (RF)-sputtering under mild conditions. Specimens are thoroughly characterized by a multi-technique approach, aimed at investigating the system properties as a function of the Ag/Au content, as well as the evolution induced by ex-situ annealing under inert (N2) or reducing (4% H2/N2) atmospheres. The obtained results demonstrate the possibility to obtain Ag-Au alloyed nanoparticles with controllable size, shape, structure, and dispersion under mild conditions, so that the optical properties can be finely tuned as a function of the synthesis and thermal treatment conditions.

Analysis of Local Structure, Chemistry and Bonding by Electron Energy Loss Spectroscopy

NASA Astrophysics Data System (ADS)

Mayer, Joachim

In the present chapter, the reader will first be introduced briefly to the basic principles of analytical transmission electron microscopy (ATEM) with special emphasis on electron energy-loss spectroscopy (EELS) and energy-filtering TEM. The quantification of spectra to obtain chemical information and the origin and interpretation of near-edge fine structures in EELS (ELNES) are discussed. Special attention will be given to the characterization of internal interfaces and the literature in this area will be reviewed. Selected examples of the application of ATEM in the investigation of internal interfaces will be given. These examples include both EELS in the energy-filtering TEM and in the scanning transmission electron microscope (STEM).

Stress-induced nematicity in EuFe 2 As 2 studied by Raman spectroscopy

DOE PAGES

Zhang, W. -L.; Sefat, Athena S.; Ding, H.; ...

2016-07-18

Here, we use polarized Raman scattering to study the structural phase transition in EuFe 2 As 2 , the parent compound of the 122-ferropnictide superconductors. The in-plane lattice anisotropy is characterized by measurements of the side surface with different strains induced by different preparation methods. We also show that while a fine surface polishing leaves the samples free of residual internal strain, in which case the onset of the C 4 symmetry breaking is observed at the nominal structural phase transition temperature T S , cutting the side surface induces a permanent fourfold rotational symmetry breaking spanning tens ofmore » degrees above T S .« less

Memory-Intensive Benchmarks: IRAM vs. Cache-Based Machines

NASA Technical Reports Server (NTRS)

Biswas, Rupak; Gaeke, Brian R.; Husbands, Parry; Li, Xiaoye S.; Oliker, Leonid; Yelick, Katherine A.; Biegel, Bryan (Technical Monitor)

2002-01-01

The increasing gap between processor and memory performance has lead to new architectural models for memory-intensive applications. In this paper, we explore the performance of a set of memory-intensive benchmarks and use them to compare the performance of conventional cache-based microprocessors to a mixed logic and DRAM processor called VIRAM. The benchmarks are based on problem statements, rather than specific implementations, and in each case we explore the fundamental hardware requirements of the problem, as well as alternative algorithms and data structures that can help expose fine-grained parallelism or simplify memory access patterns. The benchmarks are characterized by their memory access patterns, their basic control structures, and the ratio of computation to memory operation.

Multilayer porous structures of HVPE and MOCVD grown GaN for photonic applications

NASA Astrophysics Data System (ADS)

Braniste, T.; Ciers, Joachim; Monaico, Ed.; Martin, D.; Carlin, J.-F.; Ursaki, V. V.; Sergentu, V. V.; Tiginyanu, I. M.; Grandjean, N.

2017-02-01

In this paper we report on a comparative study of electrochemical processes for the preparation of multilayer porous structures in hydride vapor phase epitaxy (HVPE) and metal organic chemical vapor phase deposition (MOCVD) grown GaN. It was found that in HVPE-grown GaN, multilayer porous structures are obtained due to self-organization processes leading to a fine modulation of doping during the crystal growth. However, these processes are not totally under control. Multilayer porous structures with a controlled design have been produced by optimizing the technological process of electrochemical etching in MOCVD-grown samples, consisting of five pairs of thin layers with alternating-doping profiles. The samples have been characterized by SEM imaging, photoluminescence spectroscopy, and micro-reflectivity measurements, accompanied by transfer matrix analysis and simulations by a method developed for the calculation of optical reflection spectra. We demonstrate the applicability of the produced structures for the design of Bragg reflectors.

Fine Root Growth Phenology, Production, and Turnover in a Northern Hardwood Forest Ecosystem

Treesearch

Dudley J. Raynal

1994-01-01

A large part of the nutrient flux in deciduous forests is through fine root turnover, yet this process is seldom measured. As part of a nutrient cycling study, fine root dynamics were studied for two years at Huntington Forest in the Adirondack Mountain region of New York, USA. Root growth phenology was characterized using field rhizotrons, three methods were used to...

The wildland fuel cell concept: an approach to characterize fine-scale variation in fuels and fire in frequently burned longleaf pine forests

Treesearch

J. Kevin Hiers; Joseph J. O’Brien; R. J. Mitchell; John M. Grego; E. Louise Loudermilk

2009-01-01

In ecosystems with frequent surface fire regimes, fire and fuel heterogeneity has been largely overlookedowing to the lack of unburned patches and the difficulty in measuring fire behavior at fine scales (0.1–10 m). The diversevegetation in these ecosystems varies at these fine scales. This diversity could be...

A Compendium of Scale Surface Microstructures: Ni(pt)al Coatings Oxidized at 1150 C for 2000 1-h Cycles

NASA Technical Reports Server (NTRS)

Smialek, James L.; Garg, Anita

2010-01-01

The surface structure of scales formed on Ni(Pt)Al coatings was characterized by SEM/EDS/BSE in plan view. Two nominally identical {100} samples of aluminide coated CMSX4 single crystal were oxidized at 1150 C for 2000 1-h cycles and were found to produce somewhat disparate behavior. One sample, with less propensity for coating grain boundary ridge deformation, presented primarily alpha-Al2O3 scale structures, with minimal weight loss and spallation. The original scale structure, still retained over most of the sample, consisted of the classic theta-alpha transformation-induced ridge network structure, with approx. 25 nm crystallographic steps and terraces indicative of surface rearrangement to low energy alumina planes. The scale grain boundary ridges were often decorated with a fine, uniform distribution of (Hf,Ti)O2 particles. Another sample, producing steady state weight losses, exhibited much interfacial spallation and a complex assortment of different structures. Broad areas of interfacial spalling, crystallographically-faceted (Ni,Co)(Al,Cr)2O4 spinel, with an alpha-Al2O3 base scale, were the dominant features. Other regions exhibited nodular spinel grains, with fine or (Ta,Ti)-rich (rutile) particles decorating or interspersed with the spinel. While these features were consistent with a coating that presented more deformation at extruded grain boundaries, the root cause of the different behavior between the duplicate samples could not be conclusively identified.

Factors influencing phase compositions and structure of plasma sprayed hydroxyapatite coatings during heat treatment

NASA Astrophysics Data System (ADS)

Lu, Yu-Peng; Song, Yi-Zhong; Zhu, Rui-Fu; Li, Mu-Sen; Lei, Ting-Quan

2003-02-01

Heat treatment was expected to enhance the long-term reliability of hydroxyapatite (HA) coatings on metal substrates. In this study, factors influencing phase compositions and structure of plasma sprayed hydroxyapatite coatings during heat treatment were carefully analyzed. The phases were characterized by using X-ray diffraction (XRD), the OH - ion contents were determined by Fourier transform infrared (FTIR) spectroscopy. Of the involved factors, heating temperature is of more importance. The appropriate heat treatments is (600- 700 ° C)×2 h for coatings made from fine particles (10-20 μm) and 600 ° C×2 h for coatings made from coarse particles (50-80 μm). The excessive high temperatures and long holding times were unfavorable for the structural integrity of HA.

Electronic structure of nickel silicide in subhalf-micron lines and blanket films: An x-ray absorption fine structures study at the Ni and Si L3,2 edge

NASA Astrophysics Data System (ADS)

Naftel, S. J.; Coulthard, I.; Sham, T. K.; Xu, D.-X.; Erickson, L.; Das, S. R.

1999-05-01

We report a Ni and Si L3,2-edge x-ray absorption near edge structures (XANES) study of nickel-silicon interaction in submicron (0.15 and 0.2 μm) lines on a n-Si(100) wafer as well as a series of well characterized Ni-Si blanket films. XANES measurements recorded in both total electron yield and soft x-ray fluorescence yield indicate that under the selected silicidation conditions, the more desirable low resistivity phase, NiSi, is indeed the dominant phase in the subhalf-micron lines although the formation of this phase is less complete as the line becomes narrower and this is accompanied by a Ni rich surface.

Tailoring properties of reticulated vitreous carbon foams with tunable density

NASA Astrophysics Data System (ADS)

Smorygo, Oleg; Marukovich, Alexander; Mikutski, Vitali; Stathopoulos, Vassilis; Hryhoryeu, Siarhei; Sadykov, Vladislav

2016-06-01

Reticulated vitreous carbon (RVC) foams were manufactured by multiple replications of a polyurethane foam template structure using ethanolic solutions of phenolic resin. The aims were to create an algorithm of fine tuning the precursor foam density and ensure an open-cell reticulated porous structure in a wide density range. The precursor foams were pyrolyzed in inert atmospheres at 700°C, 1100°C and 2000°C, and RVC foams with fully open cells and tunable bulk densities within 0.09-0.42 g/cm3 were synthesized. The foams were characterized in terms of porous structure, carbon lattice parameters, mechanical properties, thermal conductivity, electric conductivity, and corrosive resistance. The reported manufacturing approach is suitable for designing the foam microstructure, including the strut design with a graded microstructure.

Congenital amusia: a cognitive disorder limited to resolved harmonics and with no peripheral basis.

PubMed

Cousineau, Marion; Oxenham, Andrew J; Peretz, Isabelle

2015-01-01

Pitch plays a fundamental role in audition, from speech and music perception to auditory scene analysis. Congenital amusia is a neurogenetic disorder that appears to affect primarily pitch and melody perception. Pitch is normally conveyed by the spectro-temporal fine structure of low harmonics, but some pitch information is available in the temporal envelope produced by the interactions of higher harmonics. Using 10 amusic subjects and 10 matched controls, we tested the hypothesis that amusics suffer exclusively from impaired processing of spectro-temporal fine structure. We also tested whether the inability of amusics to process acoustic temporal fine structure extends beyond pitch by measuring sensitivity to interaural time differences, which also rely on temporal fine structure. Further tests were carried out on basic intensity and spectral resolution. As expected, pitch perception based on spectro-temporal fine structure was impaired in amusics; however, no significant deficits were observed in amusics' ability to perceive the pitch conveyed via temporal-envelope cues. Sensitivity to interaural time differences was also not significantly different between the amusic and control groups, ruling out deficits in the peripheral coding of temporal fine structure. Finally, no significant differences in intensity or spectral resolution were found between the amusic and control groups. The results demonstrate a pitch-specific deficit in fine spectro-temporal information processing in amusia that seems unrelated to temporal or spectral coding in the auditory periphery. These results are consistent with the view that there are distinct mechanisms dedicated to processing resolved and unresolved harmonics in the general population, the former being altered in congenital amusia while the latter is spared. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Fine stereo structure for natural organic molecules, a preliminary study. II. Melting point influenced by structure factors].

PubMed

Lu, Y; Zheng, Q; Lu, D; Ma, P; Chen, Y

1995-06-01

Crystal structures of two compounds from Tripterygium wilfordii Hook f. have been determined by X-ray diffraction method. Structure factors influencing melting point of solid state have been analysed. Crystal class (or space group), recrystallization solvent, force between molecules and fine changes of molecular structures will all cause melting point changes of crystal substance.

Laser marking on soda-lime glass by laser-induced backside wet etching with two-beam interference

NASA Astrophysics Data System (ADS)

Nakazumi, Tomoka; Sato, Tadatake; Narazaki, Aiko; Niino, Hiroyuki

2016-09-01

For crack-free marking of glass materials, a beam-scanning laser-induced backside wet etching (LIBWE) process by a beam spot with a fine periodic structure was examined. The fine periodic structure was produced within a beam spot by means of a Mach-Zehnder interferometer incorporated to the optical setup for the beam-scanning LIBWE. A fine structure with a period of 9 µm was observed within the microstructures with a diameter of ca. 40 µm fabricated by a laser shot under double-beam irradiation, and they could be homogeneously fabricated within an area of 800  ×  800 µm. The area filled with the microstructures, including fine periodic structures, could be observed in high contrast under a diffuse, on-axis illumination that was used in commercial QR code readers.

3D WHOLE-PROMINENCE FINE STRUCTURE MODELING

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

Gunár, Stanislav; Mackay, Duncan H.

2015-04-20

We present the first 3D whole-prominence fine structure model. The model combines a 3D magnetic field configuration of an entire prominence obtained from nonlinear force-free field simulations, with a detailed description of the prominence plasma. The plasma is located in magnetic dips in hydrostatic equilibrium and is distributed along multiple fine structures within the 3D magnetic model. Through the use of a novel radiative transfer visualization technique for the Hα line such plasma-loaded magnetic field model produces synthetic images of the modeled prominence comparable with high-resolution observations. This allows us for the first time to use a single technique tomore » consistently study, in both emission on the limb and absorption against the solar disk, the fine structures of prominences/filaments produced by a magnetic field model.« less

[Ultraviolet spectroscopic study on the fine structures in the solar polar hole].

PubMed

Zhang, Min; Wang, Dong; Liu, Guo-Hong

2014-07-01

Fine structures in the south solar polar coronal hole were observed by N IV line of SOHO/SUMER spectrograph. The scales of the fine structures range spatially range from 1 arcsec to several arcsecs, temporally from 1 min to several minutes, and parts of them are in strip shape along the slit direction. The line-of-sight velocity of them is up to tens of km x s(-1) with red and blue shift intercrossed occasionally, which appear periodically as long as 100 minutes in some regions. Part of the fine structures can be clearly observed at the Ne V III line with higher formation temperature in the same spectral window. The time and location of some fine structures with high velocity in the Ne V III spectrum are almost the same as that in N IV spectrum, but they are extended and diffused in the Ne V III spectrum. Some fine structures have non-Gaussian profiles with the line-of-sight Doppler velocities up to 150 km x s(-1) in the N IV blue/red wings, which is similar with the explosive events in the transition region. In the past, explosive events are small-scale dynamic phenomena often observed in the quiet-sun (QS) region, while their properties in coronal holes (CHs) remain unclear. Here, we find the EE-like events with strong dynamics in the south solar polar coronal hole by N IV line of SOHO/SUMER spectrograph.

Fabrication and characterization of dichroic fine crystals by the reprecipitation method

NASA Astrophysics Data System (ADS)

Iino, Tatsuya; Mori, Shunsuke; Shito, Keiji; Kimura, Ayaka; Morishita, Yoshii; Chiba, Takayuki; Katagiri, Hiroshi; Okada, Shuji; Masuhara, Akito

2018-06-01

Suspended particle devices can rapidly switch from a dark blue state to a clear state by applying AC voltage, but their maximum transmittance has to be improved. In this work, we have targeted dichroic dyes and applied the reprecipitation method to KPD-503, a trisazo dye showing little dichroism in bulk crystals despite the dye molecules having large dichroism. As a result, microcrystals showing large dichroism were obtained. These microcrystals were considered to have a kinetically stable structure and oriented by voltage in a dispersing medium.

Identifying the Atomic-Level Effects of Metal Composition on the Structure and Catalytic Activity of Peptide-Templated Materials

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

Merrill, Nicholas A.; McKee, Erik M.; Merino, Kyle C.

2015-10-12

Bioinspired approaches for the formation of metallic nanomaterials have been extensively employed for a diverse range of applications including diagnostics and catalysis. These materials can often be used under sustainable conditions; however, it is challenging to control the material size, morphology, and composition simultaneously. Here we have employed the R5 peptide, which forms a 3D scaffold to direct the size and linear shape of bimetallic PdAu nanomaterials for catalysis. The materials were prepared at varying Pd:Au ratios to probe optimal compositions to achieve maximal catalytic efficiency. These materials were extensively characterized at the atomic level using transmission electron microscopy, extendedmore » X-ray absorption fine structure spectroscopy, and atomic pair distribution function analysis derived from high-energy X-ray diffraction patterns to provide highly resolved structural information. The results confirmed PdAu alloy formation, but also demonstrated that significant surface structural disorder was present. The catalytic activity of the materials was studied for olefin hydrogenation, which demonstrated enhanced reactivity from the bimetallic structures.These results present a pathway to the bioinspired production of multimetallic materials with enhanced properties, which can be assessed via a suite of characterization methods to fully ascertain structure/function relationships.« less

Variations in Grain-Scale Sediment Structure in a Gravel-Bed Channel as a Function of Fine Sediment Content and Morphological Location

NASA Astrophysics Data System (ADS)

Voepel, H.; Ahmed, S. I.; Hodge, R. A.; Leyland, J.; Sear, D. A.

2016-12-01

One of the major causes of uncertainty in estimates of bedload transport rates in gravel bed rivers is a lack of understanding of grain-scale sediment structure, and the impact that this structure has on bed stability. Furthermore, grain-scale structure varies throughout a channel and over time in ways that have not been fully quantified. Our research aims to quantify variations in sediment structure caused by two key variables; morphological location within a riffle-pool sequence (reflecting variation in hydraulic conditions), and the fine sediment content of the gravel bed (sand and clay). We report results from a series of flume experiments in which we water-worked a gravel bed with a riffle-pool morphology. The fine sediment content of the bed was incrementally increased over a series of runs from gravel only, to coarse sand, fine sand and two concentrations of clay. After each experimental run intact samples of the bed at different locations were extracted and the internal structure of the bed was measured using non-destructive, micro-focus X-ray computed tomography (CT) imaging. The CT images were processed to measure the properties of individual grains, including volume, center of mass, dimension, and contact points. From these data we were able to quantify the sediment structure through metrics including measurement of grain pivot angles, grain exposure and protrusion, and vertical variation in bed porosity and fine sediment content. Metrics derived from the CT data were verified using data from grain counts and tilt-table measurements on co-located samples. Comparison of the metrics across different morphological locations and fine sediment content demonstrates how these factors affect the bed structure. These results have implications for the development of sediment entrainment models for gravel bed rivers.

Fine Structure of Anomalously Intense Pulses of PSR J0814+7429 Radio Emission in the Decameter Range

NASA Astrophysics Data System (ADS)

Skoryk, A. O.; Ulyanov, O. M.; Zakharenko, V. V.; Shevtsova, A. I.; Vasylieva, I. Y.; Plakhov, M. S.; Kravtsov, I. M.

2017-06-01

Purpose: The fine structure of the anomalously intense pulses of PSR J0814+7429 (B0809+74) has been studied. The pulsar radio emission fine structure is investigated to determine its parameters in the lowest part of spectrum available for groundbased observations. Design/methodology/approach: The scattering measure in the interstellar plasma have been estimated using the spectral and correlation analyses of pulsar data recorded by the UTR-2 radio telescope. Results: Two characteristic time scales of the anomalously intense pulses fine structure of the PSR J0814+7429 radio emission have been found. The strongest pulses of this pulsar in the decameter range can have a duration of about t 2÷3 ms. These pulses are emitted in short series. In some cases, they are emitted over the low-intensity plateau consisting of the “long” subpulse component. Conclusions: The narrowest correlation scale of pulsar J0814+7429 radio emission corresponds to the doubled scattering time constant of the interstellar medium impulse response. Broader scale of the fine structure of its radio emission can be explained by the radiation of a short series of narrow pulses or relatively broad pulses inside this pulsar magnetosphere.

Chimaeric sounds reveal dichotomies in auditory perception

PubMed Central

Smith, Zachary M.; Delgutte, Bertrand; Oxenham, Andrew J.

2008-01-01

By Fourier's theorem1, signals can be decomposed into a sum of sinusoids of different frequencies. This is especially relevant for hearing, because the inner ear performs a form of mechanical Fourier transform by mapping frequencies along the length of the cochlear partition. An alternative signal decomposition, originated by Hilbert2, is to factor a signal into the product of a slowly varying envelope and a rapidly varying fine time structure. Neurons in the auditory brainstem3–6 sensitive to these features have been found in mammalian physiological studies. To investigate the relative perceptual importance of envelope and fine structure, we synthesized stimuli that we call ‘auditory chimaeras’, which have the envelope of one sound and the fine structure of another. Here we show that the envelope is most important for speech reception, and the fine structure is most important for pitch perception and sound localization. When the two features are in conflict, the sound of speech is heard at a location determined by the fine structure, but the words are identified according to the envelope. This finding reveals a possible acoustic basis for the hypothesized ‘what’ and ‘where’ pathways in the auditory cortex7–10. PMID:11882898

The Effect of Quantum-Mechanical Interference on Precise Measurements of the n = 2 Triplet P Fine Structure of Helium

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

Marsman, A.; Horbatsch, M.; Hessels, E. A., E-mail: hessels@yorku.ca

2015-09-15

For many decades, improvements in both theory and experiment of the fine structure of the n = 2 triplet P levels of helium have allowed for an increasingly precise determination of the fine-structure constant. Recently, it has been observed that quantum-mechanical interference between neighboring resonances can cause significant shifts, even if such neighboring resonances are separated by thousands of natural widths. The shifts depend in detail on the experimental method used for the measurement, as well as the specific experimental parameters employed. Here, we review how these shifts apply for the most precise measurements of the helium 2{sup 3}P fine-structuremore » intervals.« less

Formation of fine {gamma} grain structure through fine {alpha}{sub 2}/{gamma} lamellar structure in Ti-rich TiAl alloy

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

Kumagai, T.; Abe, E.; Nakamura, M.

1997-12-31

Microstructural development of an extremely fine {alpha}{sub 2}-Ti{sub 32}Al/{gamma}-TiAl lamellar structure, which was formed by ice water quenching after solution-treatment in a high-temperature {alpha}-Ti phase field for a long period of time, was examined during isothermal treatment. In an as-quenched Ti-48at.%Al alloy, the massively transformed {gamma} ({gamma}{sub m}) and untransformed (meaning massively untransformed) fine {alpha}{sub 2}/{gamma} lamellar regions were observed. Fine {gamma} grains, which were similar to {gamma}{sub m}, were generated both within the fine {alpha}{sub 2}/{gamma} lamellae and at the boundary area between the {gamma}{sub m} and the fine {alpha}{sub 2}/{gamma} lamellar regions by aging at low-temperature (1,173 K)more » for a short time (180s). Further aging (1.8ks) caused the coarsening of these newly generated fine {gamma} grains. On the other hand, the coarsening of the {gamma} grains occurred by a high-temperature (1,323 K) aging treatment even for 180s. Fine {alpha}{sub 2} plates and particles, which were aligned to a particular direction, were observed in the {gamma} grain interiors, indicating that the newly generated {gamma} grains grew at the expense of the fine {alpha}{sub 2}/{gamma} lamellae. It can be considered that the {gamma} grain formation through the fine {alpha}{sub 2}/{gamma} lamellae is closely related to the {alpha}{sub 2}{yields}{gamma} reaction of the {alpha}{sub 2} plates sandwiched by the {gamma} plates, and needs the fast heating rate enough to overcome the {alpha}{sub 2}/{gamma}{yields}{gamma}/{gamma} lamellae reaction.« less

The Apollo 15 coarse fines (4-10 mm)

NASA Technical Reports Server (NTRS)

Ryder, Graham; Sherman, Sarah Bean

1989-01-01

A new catalog of the Apollo 15 coarse fines particles is presented. Powell's macroscopic descriptions, resulting from his 1972 particle by particle binocular examination of all of the Apollo 15 4 to 10 mm fines samples, are retained. His groupings are also retained, but petrographic, chemical, and other data from later analyses are incorporated into this catalog to better characterize individual particles and describe the groups. A large number of particles have no characterization beyond that done by Powell. Complete descriptions of the particles and all known references are provided. The catalog is intended for anyone interested in the rock types collected by Dave Scott and Jim Irwin in the Hadley-Appenine region, and particularly for researchers requiring sample allocations.

Fine Structure of Trious and Excitons in Single GaAs Quantum Dots

DTIC Science & Technology

2002-08-30

RAPID COMMUNICATIONS PHYSICAL REVIEW B 66, 081310~R! ~2002!Fine structure of trions and excitons in single GaAs quantum dots J. G. Tischler, A. S ...fine structure of single localized excitons and trions. DOI: 10.1103/PhysRevB.66.081310 PACS number~ s !: 78.67.Hc, 73.21.2b, 71.35.2yAlthough the...AUTHOR( S ) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) Naval Research Laboratory

A fine structure genomic map of the region of 12q13 containing SAS and CDK4

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

Linder, C.Y.; Elkahloun, A.G.; Su, Y.A.

1994-09-01

We have recently adapted a method, originally described by Rackwitz, to the rapid restriction mapping of multiple cosmid DNA samples. Linearization of the cosmids at the lambda cohesive site using lambda terminase is followed by partial digestion with selected restriction enzymes and hybridization to oligonucleotides specific for the right or left hand termini. Partial digestions are performed in a microtiter plate thus allowing up to 12 cosmid clones to be digested with one restriction enzyme. We have applied this rapid restriction mapping method to cosmids derived from a region of chromosome 12q13 that has recently been shown to be amplifiedmore » in a variety of cancers including malignant fibrous histiocytoma, fibrosarcoma, liposarcoma, osteosarcoma and brain tumors. A small segment of this amplification unit containing three genes, SAS (a membrane protein), CDK4 (a cyclin dependent kinase) and OS-9 (a recently described cDNA) has been analyzed with the system described above. This fine structure genomic map will be useful for completing the expression map of this region as well as characterizing its pattern of amplification in tumor specimens.« less

New limits on variation of the fine-structure constant using atomic dysprosium.

PubMed

Leefer, N; Weber, C T M; Cingöz, A; Torgerson, J R; Budker, D

2013-08-09

We report on the spectroscopy of radio-frequency transitions between nearly degenerate, opposite-parity excited states in atomic dysprosium (Dy). Theoretical calculations predict that these states are very sensitive to variation of the fine-structure constant α owing to large relativistic corrections of opposite sign for the opposite-parity levels. The near degeneracy reduces the relative precision necessary to place constraints on variation of α, competitive with results obtained from the best atomic clocks in the world. Additionally, the existence of several abundant isotopes of Dy allows isotopic comparisons that suppress common-mode systematic errors. The frequencies of the 754-MHz transition in 164Dy and 235-MHz transition in 162Dy are measured over the span of two years. The linear variation of α is α·/α=(-5.8±6.9([1σ]))×10(-17)  yr(-1), consistent with zero. The same data are used to constrain the dimensionless parameter kα characterizing a possible coupling of α to a changing gravitational potential. We find that kα=(-5.5±5.2([1σ]))×10(-7), essentially consistent with zero and the best constraint to date.

Hippocampal maturity promotes memory distinctiveness in childhood and adolescence

PubMed Central

Keresztes, Attila; Bender, Andrew R.; Bodammer, Nils C.; Shing, Yee Lee

2017-01-01

Adaptive learning systems need to meet two complementary and partially conflicting goals: detecting regularities in the world versus remembering specific events. The hippocampus (HC) keeps a fine balance between computations that extract commonalities of incoming information (i.e., pattern completion) and computations that enable encoding of highly similar events into unique representations (i.e., pattern separation). Histological evidence from young rhesus monkeys suggests that HC development is characterized by the differential development of intrahippocampal subfields and associated networks. However, due to challenges in the in vivo investigation of such developmental organization, the ontogenetic timing of HC subfield maturation remains controversial. Delineating its course is important, as it directly influences the fine balance between pattern separation and pattern completion operations and, thus, developmental changes in learning and memory. Here, we relate in vivo, high-resolution structural magnetic resonance imaging data of HC subfields to behavioral memory performance in children aged 6–14 y and in young adults. We identify a multivariate profile of age-related differences in intrahippocampal structures and show that HC maturity as captured by this pattern is associated with age differences in the differential encoding of unique memory representations. PMID:28784801

Mercury Speciation by X-ray Absorption Fine Structure Spectroscopy and Sequential Chemical Extractions: A Comparison of Speciation Methods

USGS Publications Warehouse

Kim, C.S.; Bloom, N.S.; Rytuba, J.J.; Brown, Gordon E.

2003-01-01

Determining the chemical speciation of mercury in contaminated mining and industrial environments is essential for predicting its solubility, transport behavior, and potential bioavailability as well as for designing effective remediation strategies. In this study, two techniques for determining Hg speciation-X-ray absorption fine structure (XAFS) spectroscopy and sequential chemical extractions (SCE)-are independently applied to a set of samples with Hg concentrations ranging from 132 to 7539 mg/kg to determine if the two techniques provide comparable Hg speciation results. Generally, the proportions of insoluble HgS (cinnabar, metacinnabar) and HgSe identified by XAFS correlate well with the proportion of Hg removed in the aqua regia extraction demonstrated to remove HgS and HgSe. Statistically significant (> 10%) differences are observed however in samples containing more soluble Hg-containing phases (HgCl2, HgO, Hg3S2O 4). Such differences may be related to matrix, particle size, or crystallinity effects, which could affect the apparent solubility of Hg phases present. In more highly concentrated samples, microscopy techniques can help characterize the Hg-bearing species in complex multiphase natural samples.

Ecosystem structure and function in the SPRUCE chambers at fine resolution

NASA Astrophysics Data System (ADS)

Glenn, N. F.; Graham, J.; Spaete, L.; Hanson, P. J.

2017-12-01

The Spruce and Peatland Responses Under Climatic and Environmental change (SPRUCE; operated by DOE's Oak Ridge National Laboratory) aims to assess biological and ecological responses in a peat bog to a range of increased temperatures and the presence of elevated atmospheric CO2 concentrations. We are using terrestrial laser scanning (TLS) to monitor vegetation productivity and hummock-hollow structure at cm-scale in the SPRUCE plots to complement in-situ measurements of gross and net primary production. The hummock-hollow peatland microtopography is associated with fluctuating water levels and sphagnum mosses, and ultimately controls C and methane cycling. We estimate tree growth by calculating increases in tree height and canopy voxel volume between years with the TLS data. Microtopography is also characterized over time with TLS but by using gridded cells to classify regions into hummocks or hollows. Spectroscopy to quantify water content in the sphagnum is used to further classify these microtopographic regions. As multiple years of data collection occur, we will couple our fine-scale remote sensing measurements with in-situ measurements of CO2 and CH4 flux measures to capture species-specific productivity responses to warming and increased CO2.

Monte Carlo Simulations of Electron Energy-Loss Spectra with the Addition of Fine Structure from Density Functional Theory Calculations.

PubMed

Attarian Shandiz, Mohammad; Guinel, Maxime J-F; Ahmadi, Majid; Gauvin, Raynald

2016-02-01

A new approach is presented to introduce the fine structure of core-loss excitations into the electron energy-loss spectra of ionization edges by Monte Carlo simulations based on an optical oscillator model. The optical oscillator strength is refined using the calculated electron energy-loss near-edge structure by density functional theory calculations. This approach can predict the effects of multiple scattering and thickness on the fine structure of ionization edges. In addition, effects of the fitting range for background removal and the integration range under the ionization edge on signal-to-noise ratio are investigated.

Multilayer photosensitive structures based on porous silicon and rare-earth-element compounds: Study of spectral characteristics

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

Kirsanov, N. Yu.; Latukhina, N. V., E-mail: natalat@yandex.ru; Lizunkova, D. A.

2017-03-15

The spectral characteristics of the specular reflectance, photosensitivity, and photoluminescence (PL) of multilayer structures based on porous silicon with rare-earth-element (REE) ions are investigated. It is shown that the photosensitivity of these structures in the wavelength range of 0.4–1.0 μm is higher than in structures free of REEs. The structures with Er{sup 3+} ions exhibit a luminescence response at room temperature in the spectral range from 1.1 to 1.7 μm. The PL spectrum of the erbium impurity is characterized by a fine line structure, which is determined by the splitting of the {sup 4}I{sub 15/2} multiplet of the Er{sup 3+}more » ion. It is shown that the structures with a porous layer on the working surface have a much lower reflectance in the entire spectral range under study (0.2–1.0 μm).« less

A simulation for gravity fine structure recovery from high-low GRAVSAT SST data

NASA Technical Reports Server (NTRS)

Estes, R. H.; Lancaster, E. R.

1976-01-01

Covariance error analysis techniques were applied to investigate estimation strategies for the high-low SST mission for accurate local recovery of gravitational fine structure, considering the aliasing effects of unsolved for parameters. Surface density blocks of 5 deg x 5 deg and 2 1/2 deg x 2 1/2 deg resolution were utilized to represent the high order geopotential with the drag-free GRAVSAT configured in a nearly circular polar orbit at 250 km. altitude. GEOPAUSE and geosynchronous satellites were considered as high relay spacecraft. It is demonstrated that knowledge of gravitational fine structure can be significantly improved at 5 deg x 5 deg resolution using SST data from a high-low configuration with reasonably accurate orbits for the low GRAVSAT. The gravity fine structure recoverability of the high-low SST mission is compared with the low-low configuration and shown to be superior.

Revisiting place and temporal theories of pitch

PubMed Central

2014-01-01

The nature of pitch and its neural coding have been studied for over a century. A popular debate has revolved around the question of whether pitch is coded via “place” cues in the cochlea, or via timing cues in the auditory nerve. In the most recent incarnation of this debate, the role of temporal fine structure has been emphasized in conveying important pitch and speech information, particularly because the lack of temporal fine structure coding in cochlear implants might explain some of the difficulties faced by cochlear implant users in perceiving music and pitch contours in speech. In addition, some studies have postulated that hearing-impaired listeners may have a specific deficit related to processing temporal fine structure. This article reviews some of the recent literature surrounding the debate, and argues that much of the recent evidence suggesting the importance of temporal fine structure processing can also be accounted for using spectral (place) or temporal-envelope cues. PMID:25364292

The uniformity study of non-oxide thin film at device level using electron energy loss spectroscopy

NASA Astrophysics Data System (ADS)

Li, Zhi-Peng; Zheng, Yuankai; Li, Shaoping; Wang, Haifeng

2018-05-01

Electron energy loss spectroscopy (EELS) has been widely used as a chemical analysis technique to characterize materials chemical properties, such as element valence states, atoms/ions bonding environment. This study provides a new method to characterize physical properties (i.e., film uniformity, grain orientations) of non-oxide thin films in the magnetic device by using EELS microanalysis on scanning transmission electron microscope. This method is based on analyzing white line ratio of spectra and related extended energy loss fine structures so as to correlate it with thin film uniformity. This new approach can provide an effective and sensitive method to monitor/characterize thin film quality (i.e., uniformity) at atomic level for thin film development, which is especially useful for examining ultra-thin films (i.e., several nanometers) or embedded films in devices for industry applications. More importantly, this technique enables development of quantitative characterization of thin film uniformity and it would be a remarkably useful technique for examining various types of devices for industrial applications.

Usage of Crushed Concrete Fines in Decorative Concrete

NASA Astrophysics Data System (ADS)

Pilipenko, Anton; Bazhenova, Sofia

2017-10-01

The article is devoted to the questions of usage of crushed concrete fines from concrete scrap for the production of high-quality decorative composite materials based on mixed binder. The main problem in the application of crushed concrete in the manufacture of decorative concrete products is extremely low decorative properties of crushed concrete fines itself, as well as concrete products based on them. However, crushed concrete fines could have a positive impact on the structure of the concrete matrix and could improve the environmental and economic characteristics of the concrete products. Dust fraction of crushed concrete fines contains non-hydrated cement grains, which can be opened in screening process due to the low strength of the contact zone between the hydrated and non-hydrated cement. In addition, the screening process could increase activity of the crushed concrete fines, so it can be used as a fine aggregate and filler for concrete mixes. Previous studies have shown that the effect of the usage of the crushed concrete fines is small and does not allow to obtain concrete products with high strength. However, it is possible to improve the efficiency of the crushed concrete fines as a filler due to the complex of measures prior to mixing. Such measures may include a preliminary mechanochemical activation of the binder (cement binder, iron oxide pigment, silica fume and crushed concrete fines), as well as the usage of polycarboxylate superplasticizers. The development of specific surface area of activated crushed concrete fines ensures strong adhesion between grains of binder and filler during the formation of cement stone matrix. The particle size distribution of the crushed concrete fines could achieve the densest structure of cement stone matrix and improve its resistance to environmental effects. The authors examined the mechanisms of structure of concrete products with crushed concrete fines as a filler. The results of studies of the properties of the crushed concrete fines were provided. It is shown that the admixture of the crushed concrete fines has little effect on the colour characteristics of the decorative concrete products. The preferred options to improve the surfaces of decorative concrete are also proposed.

Persistent fine-scale fault structures control rupture development in Parkfield, CA.

NASA Astrophysics Data System (ADS)

Perrin, C.; Waldhauser, F.; Scholz, C. H.

2016-12-01

We investigate the fine-scale geometry and structure of the San Andreas Fault (SAF) near Parkfield, CA, and their role in the development of the 1966 and 2004 M6 earthquakes. Both events broke the fault mainly unilaterally with similar length ( 30 km) but in opposite directions. Seismic slip occurred in a narrow zone between 5 and 10 km depth, as outlined by the concentration of aftershocks along the edge of the slip area. Across fault distribution of the 2004 aftershocks show a rapid decrease of event density away from the fault core. The damage zone is narrower in the Parkfield section (few 100 meters) than in the creeping section ( 1 km). We observe a similar but broader distribution during the interseismic periods. This implies that stress accumulates in a volume around the fault during interseismic periods, whereas coseismic deformation is more localized on the mature SAF. Large aftershocks are concentrated at both rupture tips, characterized by strong heterogeneities in the fault structure at the surface and at depth: i) in the south near Gold Hill-Cholame, a large releasing bend (>25°) separates the Parkfield section from the southern section of the SAF; ii) in the north at Middle Mountain, the surface fault trace goes through an ancient restraining step-over connecting the Parkfield and creeping sections. Fine-scale analysis of the 2004 aftershocks reveals a change in the fault dip and local variations of the fault strike (up to 25°) beneath Middle Mountain, in good agreement with focal mechanisms, which show oblique normal and reverse faulting. We observe these variations during the interseismic periods before and after the 2004 event, suggesting that the structural heterogeneities persisted through at least two earthquake cycles. These heterogeneities act as barriers to rupture propagation of moderate size earthquakes at Parkfield, but also as stress concentrations where rupture initiates.

Sequence of structures in fine-grained turbidites: Comparison of recent deep-sea and ancient flysch sediments

NASA Astrophysics Data System (ADS)

Stow, Dorrik A. V.; Shanmugam, Ganapathy

1980-01-01

A comparative study of the sequence of sedimentary structures in ancient and modern fine-grained turbidites is made in three contrasting areas. They are (1) Holocene and Pleistocene deep-sea muds of the Nova Scotian Slope and Rise, (2) Middle Ordovician Sevier Shale of the Valley and Ridge Province of the Southern Appalachians, and (3) Cambro-Ordovician Halifax Slate of the Meguma Group in Nova Scotia. A standard sequence of structures is proposed for fine-grained turbidites. The complete sequence has nine sub-divisions that are here termed T 0 to T 8. "The lower subdivision (T 0) comprises a silt lamina which has a sharp, scoured and load-cast base, internal parallel-lamination and cross-lamination, and a sharp current-lineated or wavy surface with 'fading-ripples' (= Type C etc. …)." (= Type C ripple-drift cross-lamination, Jopling and Walker, 1968). The overlying sequence shows textural and compositional grading through alternating silt and mud laminae. A convolute-laminated sub-division (T 1) is overlain by low-amplitude climbing ripples (T 2), thin regular laminae (T 3), thin indistinct laminae (T 4), and thin wipsy or convolute laminae (T 5). The topmost three divisions, graded mud (T 6), ungraded mud (T 7) and bioturbated mud (T 8), do not have silt laminae but rare patchy silt lenses and silt pseudonodules and a thin zone of micro-burrowing near the upper surface. The proposed sequence is analogous to the Bouma (1962) structural scheme for sandy turbidites and is approximately equivalent to Bouma's (C)DE divisions. The repetition of partial sequences characterizes different parts of the slope/base-of-slope/basin plain environment, and represents deposition from different stages of evolution of a large, muddy, turbidity flow. Microstructural detail and sequence are well preserved in ancient and even slightly metamorphosed sediments. Their recognition is important for determining depositional processes and for palaeoenvironmental interpretation.

Maltose conjugation to PCL: Advanced structural characterization and preliminary biological properties

NASA Astrophysics Data System (ADS)

Secchi, Valeria; Guizzardi, Roberto; Russo, Laura; Pastori, Valentina; Lecchi, Marzia; Franchi, Stefano; Iucci, Giovanna; Battocchio, Chiara; Cipolla, Laura

2018-05-01

The emerging trends in regenerative medicine rely among others on biomaterial-based therapies, with the use of biomaterials as a central delivery system for biochemical and physical cues to manipulate transplanted or ingrowth cells and to orchestrate tissue regeneration. Cell adhesion properties of a biomaterial strongly depend on its surface characteristics. Among others poly(ε-caprolactone) (PCL) is a biocompatible and biodegradable material with low cytotoxicity that is widely adopted as synthetic polymer in several applications. However, it is hydrophobic, which limits its use in tissue engineering. In order to improve its hydrophilicity and cellular compatibility, PCL surface was grafted with maltose through a two-step procedure in which controlled aminolysis of PCL ester bonds by hexanediamine was followed by reductive amination with the carbohydrate reducing end. The modified PCL surface was then characterized in detail by x-ray Photoelectron Spectroscopy (XPS) and Near Edge x-ray Absorption Fine Structure (NEXAFS) spectroscopies. In addition, the biocompatibility of the proposed biomaterial was investigated in preliminary biological assays.

P-polarized reflectance spectroscopy: A high sensitive real-time monitoring technique to study surface kinetics under steady state epitaxial deposition conditions

NASA Technical Reports Server (NTRS)

Dietz, Nikolaus; Bachmann, Klaus J.

1995-01-01

This paper describes the results of real-time optical monitoring of epitaxial growth processes by p-polarized reflectance spectroscopy (PRS) using a single wavelength application under pulsed chemical beam epitaxy (PCBE) condition. The high surface sensitivity of PRS allows the monitoring of submonolayer precursors coverage on the surface as shown for GaP homoepitaxy and GaP on Si heteroepitaxy as examples. In the case of heteroepitaxy, the growth rate and optical properties are revealed by PRS using interference oscillations as they occur during growth. Super-imposed on these interference oscillations, the PRS signal exhibits a fine structure caused by the periodic alteration of the surface chemistry by the pulsed supply of chemical precursors. This fine structure is modeled under conditions where the surface chemistry cycles between phosphorus supersaturated and phosphorus depleted surfaces. The mathematical model describes the fine structure using a surface layer that increases during the tertiarybutyl phosphine (TBP) supply and decreases during and after the triethylgallium (TEG) pulse, which increases the growing GaP film thickness. The imaginary part of the dielectric function of the surface layer is revealed from the turning points in the fine structure, where the optical response to the first precursor pulse in the cycle sequence changes sign. The amplitude of the fine structure is determined by the surface layer thickness and the complex dielectric functions for the surface layer with the underlying bulk film. Surface kinetic data can be obtained by analyzing the rise and decay transients of the fine structure.

Imaging the atomic structure and local chemistry of platelets in natural type Ia diamond

NASA Astrophysics Data System (ADS)

Olivier, E. J.; Neethling, J. H.; Kroon, R. E.; Naidoo, S. R.; Allen, C. S.; Sawada, H.; van Aken, P. A.; Kirkland, A. I.

2018-03-01

In the past decades, many efforts have been devoted to characterizing {001} platelet defects in type Ia diamond. It is known that N is concentrated at the defect core. However, an accurate description of the atomic structure of the defect and the role that N plays in it is still unknown. Here, by using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy we have determined the atomic arrangement within platelet defects in a natural type Ia diamond and matched it to a prevalent theoretical model. The platelet has an anisotropic atomic structure with a zigzag ordering of defect pairs along the defect line. The electron energy-loss near-edge fine structure of both carbon K- and nitrogen K-edges obtained from the platelet core is consistent with a trigonal bonding arrangement at interstitial sites. The experimental observations support an interstitial aggregate mode of formation for platelet defects in natural diamond.

Imaging the atomic structure and local chemistry of platelets in natural type Ia diamond.

PubMed

Olivier, E J; Neethling, J H; Kroon, R E; Naidoo, S R; Allen, C S; Sawada, H; van Aken, P A; Kirkland, A I

2018-03-01

In the past decades, many efforts have been devoted to characterizing {001} platelet defects in type Ia diamond. It is known that N is concentrated at the defect core. However, an accurate description of the atomic structure of the defect and the role that N plays in it is still unknown. Here, by using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy we have determined the atomic arrangement within platelet defects in a natural type Ia diamond and matched it to a prevalent theoretical model. The platelet has an anisotropic atomic structure with a zigzag ordering of defect pairs along the defect line. The electron energy-loss near-edge fine structure of both carbon K- and nitrogen K-edges obtained from the platelet core is consistent with a trigonal bonding arrangement at interstitial sites. The experimental observations support an interstitial aggregate mode of formation for platelet defects in natural diamond.

Dependence of CO2 Reactivity of Carbon Anodes on Pore Structure

NASA Astrophysics Data System (ADS)

Chen, Tong; Xue, Jilai; Lang, Guanghui; Liu, Rui; Gao, Shoulei; Wang, Zengjie

2017-09-01

The correlation between the CO2 reactivity and pore structure of carbon anodes was experimentally investigated. The pore structures of the anodes before and after CO2 oxidation were characterized using image analysis. The porosity, mean pore diameter, and the number of micro-cracks decreased with increasing anode forming pressure, while they increased with over-compaction. With prolonged CO2 oxidation time, the porosity, pore density, mean pore diameter, pore aspect ratio, and the number of micro-cracks increased due to the merging of small pores, increased pore connectivity, and generation of new pores. The activation energy decreased with increasing porosity of the anodes' pitch phase due to easier CO2 penetration and reaction within the anodes. The results confirm that the fine pitch-coke phase of anodes is preferentially consumed, a cause of carbon dusting. Optimization of the pore structures to balance the pitch, coke, and butt phases may potentially further reduce carbon dusting.

Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

PubMed

Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

2015-11-01

Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

Evolution of twinning in extruded AZ31 alloy with bimodal grain structure

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

Garcés, G., E-mail: ggarces@cenim.csic.es

2017-04-15

Twinning in extruded AZ31 alloy with a bimodal grain structure is studied under compression along the extrusion direction. This study has combined in-situ measurements during the compression tests by Synchrotron Radiation Diffraction and Acoustic Emission techniques and the evaluation of the microstructure and texture in post-mortem compression samples deformed at different strains. The microstructure of the alloy is characterized by the coexistence of large areas of fine dynamic recrystallized grains and coarse non-recrystallized grains elongated along extrusion direction. Twinning occurs initially in large elongated grains before the macroscopic yield stress which is controlled by the twinning in equiaxed dynamically recrystallizedmore » grains. - Highlights: • The AZ31 extruded at low temperature exhibits a bimodal grains structure. • Twinning takes place before macroscopic yielding in coarse non-DRXed grains. • DRXed grains controls the beginning of plasticity in magnesium alloys with bimodal grain structure.« less

Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

Treesearch

Gretchen H. Roffler; Sandra L. Talbot; Gordon Luikart; George K. Sage; Kristy L. Pilgrim; Layne G. Adams; Michael K. Schwartz

2014-01-01

Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale...

Energy, fine structure, hyperfine structure, and radiative transition rates of the high-lying multi-excited states for B-like neon

NASA Astrophysics Data System (ADS)

Zhang, Chun Mei; Chen, Chao; Sun, Yan; Gou, Bing Cong; Shao, Bin

2015-04-01

The Rayleigh-Ritz variational method with multiconfiguration interaction wave functions is used to obtain the energies of high-lying multi-excited quartet states 1 s 22 s2 pnl and 1 s 22 p 2 nl 4Pe,o ( n ≥ 2) in B-like neon, including the mass polarization and relativistic corrections. The fine structure and hyperfine structure of the excited quartet states for this system are investigated. Configuration structures of the high-lying multi-excited series are further identified by relativistic corrections and fine structure splittings. The transition rates and wavelengths are also calculated. Calculated wavelengths include the quantum electrodynamic effects. The results are compared with other theoretical and experimental data in the literature.

Designing fine aggregate mixtures to evaluate fatigue crack-growth in asphalt mixtures.

DOT National Transportation Integrated Search

2011-04-01

Fatigue cracking is a significant form of pavement distress in flexible pavements. The properties of the : sand-asphalt mortars or fine aggregate matrix (FAM) can be used to characterize the evolution of fatigue : crack growth and self-healing in asp...

Direct identification of trace metals in fine and ultrafine particles in the Detroit urban atmosphere.

PubMed

Utsunomiya, Satoshi; Jensen, Keld A; Keeler, Gerald J; Ewing, Rodney C

2004-04-15

Exposure to airborne particulates containing low concentrations of heavy metals, such as Pb, As, and Se, may have serious health effects. However, little is known about the speciation and particle size of these airborne metals. Fine- and ultrafine particles with heavy metals in aerosol samples from the Detroit urban area, Michigan, were examined in detail to investigate metal concentrations and speciation. The characterization of individual particles was completed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with conventional high-resolution TEM techniques. The trace elements, Pb, As, La, Ce, Sr, Zn, Cr, Se, Sn, Y, Zr, Au, and Ag, were detected, and the elemental distributions were mapped in situ atthe nanoscale. The crystal structures of the particles containing Pb, Sr, Zn, and Au were determined from their electron diffraction patterns. Based on the characterization of the representative trace element particles, the potential health effects are discussed. Most of the trace element particles detected in this study were within a range of 0.01-1.0 microm in size, which has the longest atmospheric residence time (approximately 100 days). Increased chemical reactivity owing to the size of nanoparticles may be expected for most of the trace metal particles observed.

Note: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin films

DOE PAGES

Pröller, Stephan; Moseguí González, Daniel; Zhu, Chenhuii; ...

2017-06-01

In order to tailor the assembling of polymers and organic molecules, a deeper understanding of the kinetics involved in thin film production is necessary. While post-production characterization only provides insight on the final film structure, more sophisticated experimental setups are needed to probe the structure formation processes in situ during deposition. The drying kinetics of a deposited organic thin film strongly influences the assembling process on the nanometer scale. Lastly, this work presents an experimental setup that enables fine control of the atmosphere composition surrounding the sample during slot die coating, while simultaneously probing the film formation kinetics using inmore » situ grazing incidence X-ray scattering and spectroscopy.« less

Microstructure characterization and corrosion resistance properties of Pb-Sb alloys for lead acid battery spine produced by different casting methods.

PubMed

Seikh, Asiful H; Sherif, El-Sayed M; Khan Mohammed, Sohail M A; Baig, Muneer; Alam, Mohammad Asif; Alharthi, Nabeel

2018-01-01

The aim of this study is to find out the microstructure, hardness, and corrosion resistance of Pb-5%Sb spine alloy. The alloy has been produced by high pressure die casting (HPDC), medium pressure die casting (AS) and low pressure die casting (GS) methods, respectively. The microstructure was characterized by using optical microscopy and scanning electron microscopy (SEM). The hardness was also reported. The corrosion resistance of the spines in 0.5M H2SO4 solution has been analyzed by measuring the weight loss, impedance spectroscopy and the potentiodynamic polarization techniques. It has been found that the spine produced by HPDC has defect-free fine grain structure resulting improvement in hardness and excellent corrosion resistance.

Microstructure characterization and corrosion resistance properties of Pb-Sb alloys for lead acid battery spine produced by different casting methods

PubMed Central

Baig, Muneer; Alam, Mohammad Asif; Alharthi, Nabeel

2018-01-01

The aim of this study is to find out the microstructure, hardness, and corrosion resistance of Pb-5%Sb spine alloy. The alloy has been produced by high pressure die casting (HPDC), medium pressure die casting (AS) and low pressure die casting (GS) methods, respectively. The microstructure was characterized by using optical microscopy and scanning electron microscopy (SEM). The hardness was also reported. The corrosion resistance of the spines in 0.5M H2SO4 solution has been analyzed by measuring the weight loss, impedance spectroscopy and the potentiodynamic polarization techniques. It has been found that the spine produced by HPDC has defect-free fine grain structure resulting improvement in hardness and excellent corrosion resistance. PMID:29668709

Precision measurement of the three 2(3)P(J) helium fine structure intervals.

PubMed

Zelevinsky, T; Farkas, D; Gabrielse, G

2005-11-11

The three 2(3)P fine structure intervals of 4H are measured at an improved accuracy that is sufficient to test two-electron QED theory and to determine the fine structure constant alpha to 14 parts in 10(9). The more accurate determination of alpha, to a precision higher than attained with the quantum Hall and Josephson effects, awaits the reconciliation of two inconsistent theoretical calculations now being compared term by term. A low pressure helium discharge presents experimental uncertainties quite different than for earlier measurements and allows direct measurements of light pressure shifts.

Collisional excitation of CH2 rotational/fine-structure levels by helium

NASA Astrophysics Data System (ADS)

Dagdigian, P. J.; Lique, F.

2018-02-01

Accurate determination of the abundance of CH2 in interstellar media relies on both radiative and collisional rate coefficients. We investigate here the rotational/fine-structure excitation of CH2 induced by collisions with He. We employ a recoupling technique to generate fine-structure-resolved cross-sections and rate coefficients from close coupling spin-free scattering calculations. The calculations are based on a recent, high-accuracy CH2-He potential energy surface computed at the coupled clusters level of theory. The collisional cross-section calculations are performed for all fine-structure transitions among the first 22 and 24 energy levels of ortho- and para-CH2, respectively, and for temperatures up to 300 K. As a first application, we simulate the excitation of CH2 in typical molecular clouds. The excitation temperatures of the CH2 lines are found to be small at typical densities of molecular clouds, showing that the non-local thermodynamic equilibrium approach has to be used to analyse interstellar spectra. We also found that the fine-structure lines connected with the 404 - 313 and 505 - 414 rotational transitions show possible maser emissions so that they can be easily seen in emission. These calculations show that CH2 may have to be detected mainly through absorption spectra.

Fine structure in plasma waves and radiation near the plasma frequency in Earth's foreshock

NASA Technical Reports Server (NTRS)

Cairns, Iver H.

1994-01-01

Novel observations are presented of intrunsic fine structure in the frequency spectrum of electomagnetic (EM) radiation and plasma waves near the electron plasma frequency f(sub p) during a period of unusually high interplanetary magnetic field strength. Measured using the wideband receiver on the International Sun-Earth Explorer (ISEE) 1 spacecraft, fine-structured emissions are observed both in the solar wind and the foreshock, The fine structure is shown to correspond to emissions spaced above f(sub p) near half harmonies of the electon cyclotron frequency f(sub ce), i.e., near f(sub p) + nf(sub ce)/2. These appear to be the first space physics observations of emissions spaced by f(sub ce)/2. Indirect but strong arguments are used to discriminate between EM and electrostatic (ES) signals, to identify whether ISEE 1 is in the solar wind or the foreshock, and to determine the relative frequencies of the emissions and the local f(sub p). The data are consistent with generation of the ES and EM emissions in the foreshock, with subsequent propagation of the EM emissions into the solar wind. It remains possible that some emissions currently identified as ES have significant EM character. The ES and EM emisions often merge into one another with minimal changes in frequency, arguing that their source regions and generation mechanisms are related and imposing significant constraints on theories. The f(sub ce)/2 ES and EM fine structures observed may be intrinsic to the emission mechanisms or to superposition of two series of signals with f(sub ce) spacing that differ in starting frequency by f(sub ce)/2. Present theories for nonlinear wave coupling processes, cyclotron maser emission, and other linear instability processes are all unable to explain multiple EM and/or ES components spaced by approximately f(sub ce)/2 above f(sub p) for f(sub p)/f(sub ce) much greater than 1 and typical for shock beams parameters. Suitable avenues for further theoretical research are identified. Empirically, the observed fine structures appear very similar to those in split bnad and multiple-lane type II solar radio bursts; interpretation of both these type II fine structures in terms of f(sub ce)/2 splitting is suggested, thereby supporting and generalizing a suggestion by Wild (1950). A possible application to continuum radiation is mentioned. The ubiquity of these fine structures in the Earth's f(sub p) radiation and foreshock waves remains unknown. Only the ISEE 1 wideband receiver has sufficient frequency resolution (approximately less than or equal to 100 Hz) to perform a dedicated search. Further study of the ubiquity of these fine structures, of how reliably the splitting corresponds to f(sub ce)/2, and of the other interpretations above is necessary.

Alternative Fluoropolymers to Avoid the Challenges Associated with Perfluorooctanoic Acid

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

Guo,J.; Resnick, P.; Efimenko, K.

2008-01-01

The degradation of stain-resistant coating materials leads to the release of biopersistent perfluorooctanoic acid (PFOA) to the environment. In order to find the environmentally friendly substitutes, we have designed and synthesized a series of nonbiopersistant fluorinated polymers containing perfluorobutyl groups in the side chains. The surface properties of the new coating materials were characterized by static and dynamic contact angle measurements. The new coating materials demonstrate promising hydrophobic and oleophobic properties with low surfaces tensions. The wetting properties and surface structure of the polymers were tuned by varying the 'spacer' structures between the polymer backbones and the perfluorinated groups ofmore » the side chains. The relationship between orientations of the fluorinated side chains and performances of polymer surfaces were further investigated by near-edge X-ray fine absorption structure (NEXAFS) experiments and differential scanning calorimetry (DSC).« less

A Modeling Framework for Improved Characterization of Near-Road Exposure at Fine Scales

EPA Science Inventory

Traffic-related air pollutants could cause adverse health impact to communities near roadways. To estimate the population risk and locate "hotspots" in the near-road environment, quantifying the exposure at a fine spatial resolution is essential. A new state-of-the-art ...

Synthesis, characterization and study of arsenate adsorption from aqueous solution by {alpha}- and {delta}-phase manganese dioxide nanoadsorbents

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

Singh, Mandeep; Thanh, Dong Nguyen, E-mail: Dong.Nguyen.Thanh@vscht.c; Ulbrich, Pavel

2010-12-15

Single-phase {alpha}-MnO{sub 2} nanorods and {delta}-MnO{sub 2} nano-fiber clumps were synthesized using manganese pentahydrate in an aqueous solution. These nanomaterials were characterized using the Transmission Electron Microscope (TEM), Field Emission Scanning Electron Microscope (FE-SEM), Powder X-ray diffraction (XRD) and the Brunauer-Elmet-Teller nitrogen adsorption technique (BET-N{sub 2} adsorption). The structural analysis shows that {alpha}-MnO{sub 2} (2x2 tunnel structure) has the form of needle-shaped nanorods and {delta}-MnO{sub 2} (2D-layered structure) consists of fine needle-like fibers arranged in ball-like aggregates. Batch adsorption experiments were carried out to determine the effect of pH on adsorption kinetics and adsorption capacity for the removal of As(V)more » from aqueous solution onto these two types of nanoadsorbents. The adsorption capacity of As(V) was found to be highly pH dependent. The adsorption of As(V) onto {alpha}-MnO{sub 2} reached equilibrium more rapidly with higher adsorption capacity compared to {delta}-MnO{sub 2}. -- Graphical abstract: {alpha}-MnO{sub 2} (2x2 tunnel structure) nanorods and {delta}-MnO{sub 2} (2-D layered structure) nano-fiber clumps were synthesized in a facile way in an aqueous solution and characterized by TEM, FE-SEM, XRD and BET-N{sub 2} adsorption techniques. The structural analysis shows that {alpha}-MnO{sub 2} is needle shaped nanorods and {delta}-MnO{sub 2} consists of 2-D platelets of fine needle-like fibers arranged in ball-like aggregates. Further batch experiments confirmed that both nanoadsorbents are potential candidates for the adsorption of As(V) with a capacity of 19.41 and 15.33 mg g{sup -1} for {alpha}-MnO{sub 2} and {delta}-MnO{sub 2}, respectively. The presence of As3d peak in XPS study indicates that arsenic on the surface of nanoadsorbents is in the stable form of As(V) with a percentage of arsenate onto {alpha}-MnO{sub 2} is 0.099% as compared to 0.021% onto {delta}-MnO{sub 2}, clearly indicating the higher adsorption of As(V) in case of {alpha}-MnO{sub 2} as compared to {delta}-MnO{sub 2}, which is in good agreement with the adsorption studies results. Display Omitted« less

Structural, microstructural and magnetic evolution in cryo milled carbon doped MnAl.

PubMed

Fang, Hailiang; Cedervall, Johan; Hedlund, Daniel; Shafeie, Samrand; Deledda, Stefano; Olsson, Fredrik; von Fieandt, Linus; Bednarcik, Jozef; Svedlindh, Peter; Gunnarsson, Klas; Sahlberg, Martin

2018-02-06

The low cost, rare earth free τ-phase of MnAl has high potential to partially replace bonded Nd 2 Fe 14 B rare earth permanent magnets. However, the τ-phase is metastable and it is experimentally difficult to obtain powders suitable for the permanent magnet alignment process, which requires the fine powders to have an appropriate microstructure and high τ-phase purity. In this work, a new method to make high purity τ-phase fine powders is presented. A high purity τ-phase Mn 0.55 Al 0.45 C 0.02 alloy was synthesized by the drop synthesis method. The drop synthesized material was subjected to cryo milling and  followed by a flash heating process. The crystal structure and microstructure of the drop synthesized, cryo milled and flash heated samples were studied by X-ray in situ powder diffraction, scanning electron microscopy, X-ray energy dispersive spectroscopy and electron backscatter diffraction. Magnetic properties and magnetic structure of the drop synthesized, cryo milled, flash heated  samples were characterized by magnetometry and neutron powder diffraction, respectively. The results reveal that the 2 and 4 hours cryo milled and flash heated samples both exhibit high τ-phase purity and micron-sized round particle shapes. Moreover, the flash heated samples display high saturation magnetization as well as increased coercivity.

High Resolutions Studies of the Structure of the Solar Atmosphere

DTIC Science & Technology

1992-06-30

Pairs in the Solar Wind", submitted to J. Geophys. Res., July 20, 1992. M. Karovska , F. Blundell and S. R. Habbal, "Fine Scale Structure of Active...Regions", manuscript in preparation. M. Karovska , F. Blundell and S. R. Habbal, "Fine Scale Structure of the Solar Limb in a Coronal Hole", manuscript in

Fine-scale genetic structure of whitebark pine (Pinus albicaulis) associations with watershed and growth form

Treesearch

Deborah L. Rogers; Constance I. Millar; Robert D. Westfall

1999-01-01

The fine-scale genetic structure of a subalpine conifer, whitebark pine (Pinus albicaulis Engelm.), was studied at nested geographic levels from watershed to adjacent stems in the eastern Sierra Nevada Range of California. A combination of several characteristics contributed to unpredicted genetic structure in this species. This includes being one of...

Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization.

PubMed

Germann, Matthias; Willitsch, Stefan

2016-07-28

We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O2 reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ions produced by photoionization.

Sedimentary Parameters Controlling Occurrence and Preservation of Microbial Mats in Siliciclastic Depositional Systems

NASA Technical Reports Server (NTRS)

Noffke, Nora; Knoll, Andrew H.

2001-01-01

Shallow-marine, siliciclastic depositional systems are governed by physical sedimentary processes. Mineral precipitation or penecontemporaneous cementation play minor roles. Today, coastal siliciclastic environments may be colonized by a variety of epibenthic, mat-forming cyanobacteria. Studies on microbial mats showed that they are not randomly distributed in modern tidal environments. Distribution and abundancy is mainly function of a particular sedimentary facies. Fine-grained sands composed of "clear" (translucent) quartz particles constitute preferred substrates for cyanobacteria. Mat-builders also favor sites characterized by moderate hydrodynamic flow regimes, which permit biomass enrichment and construction of mat fabrics without lethal burial of mat populations by fine sediments. A comparable facies relationship can be observed in ancient siliciclastic shelf successions from the terminal Neoproterozoic Nama Group, Namibia. Wrinkle structures that record microbial mats are present but sparsely distributed in mid- to inner shelf sandstones of the Nudaus Formation. The sporadic distribution of these structures reflects both the narrow ecological window that governs mat development and the distinctive taphonomic conditions needed to preserve the structures. These observations caution that statements about changing mat abundance across the Proterozoic-Cambrian boundary must be firmly rooted in paleoenvironmental and taphonomic analysis. Understanding the factors that influence the formation and preservation of microbial structures in siliciclastic regimes can facilitate exploration for biological signatures in Earth's oldest rocks. Moreover, insofar as these structures can be preserved on bedding surfaces and are not easily mimicked by physical processes, they constitute a set of biological markers that can be searched for on Mars by remotely controlled rovers.

Structural characterization of anion-calcium-humate complexes in phosphate-based fertilizers.

PubMed

Baigorri, Roberto; Urrutia, Oscar; Erro, Javier; Mandado, Marcos; Pérez-Juste, Ignacio; Garcia-Mina, José María

2013-07-01

Fertilizers based on phosphate-metal-humate complexes are a new family of compounds that represents a more sustainable and bioavailable phosphorus source. The characterization of this type of complex by using solid (31)P NMR in several fertilizers, based on single superphosphate (SSP) and triple superphosphate (TSP) matrices, yielded surprising and unexpected trends in the intensity and fine structure of the (31)P NMR peaks. Computational chemistry methods allowed the characterization of phosphate-calcium-humate complexes in both SSP and TSP matrices, but also predicted the formation of a stable sulfate-calcium-humate complex in the SSP fertilizers, which has not been described previously. The stability of this complex has been confirmed by using ultrafiltration techniques. Preference towards the humic substance for the sulfate-metal phase in SSP allowed the explanation of the opposing trends that were observed in the experimental (31)P NMR spectra of SSP and TSP samples. Additionally, computational chemistry has provided an assignment of the (31)P NMR signals to different phosphate ligands as well as valuable information about the relative strength of the phosphate-calcium interactions within the crystals. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The contribution of visual information to the perception of speech in noise with and without informative temporal fine structure

PubMed Central

Stacey, Paula C.; Kitterick, Pádraig T.; Morris, Saffron D.; Sumner, Christian J.

2017-01-01

Understanding what is said in demanding listening situations is assisted greatly by looking at the face of a talker. Previous studies have observed that normal-hearing listeners can benefit from this visual information when a talker's voice is presented in background noise. These benefits have also been observed in quiet listening conditions in cochlear-implant users, whose device does not convey the informative temporal fine structure cues in speech, and when normal-hearing individuals listen to speech processed to remove these informative temporal fine structure cues. The current study (1) characterised the benefits of visual information when listening in background noise; and (2) used sine-wave vocoding to compare the size of the visual benefit when speech is presented with or without informative temporal fine structure. The accuracy with which normal-hearing individuals reported words in spoken sentences was assessed across three experiments. The availability of visual information and informative temporal fine structure cues was varied within and across the experiments. The results showed that visual benefit was observed using open- and closed-set tests of speech perception. The size of the benefit increased when informative temporal fine structure cues were removed. This finding suggests that visual information may play an important role in the ability of cochlear-implant users to understand speech in many everyday situations. Models of audio-visual integration were able to account for the additional benefit of visual information when speech was degraded and suggested that auditory and visual information was being integrated in a similar way in all conditions. The modelling results were consistent with the notion that audio-visual benefit is derived from the optimal combination of auditory and visual sensory cues. PMID:27085797

FINE SCALE AIR QUALITY MODELING USING DISPERSION AND CMAQ MODELING APPROACHES: AN EXAMPLE APPLICATION IN WILMINGTON, DE

EPA Science Inventory

Characterization of spatial variability of air pollutants in an urban setting at fine scales is critical for improved air toxics exposure assessments, for model evaluation studies and also for air quality regulatory applications. For this study, we investigate an approach that su...

Microstructural Characterization of Red Mud as Affected by Inorganic and Organic Chemicals Permeation

NASA Astrophysics Data System (ADS)

Rubinos, David A.; Valcárcel, Víctor; Spagnoli, Giovanni; Barral, María Teresa

2017-09-01

The microstructural characteristics of red mud (RM), especially specific surface area (SSA) and mesoporosity, and the effects of various representative fluids, namely methanol (80% v/v), trichloroethylene (TCE) (1100 mg/L), acetic acid (pH 2), and CaCl2 (5% w/v) aqueous solutions, were studied using N2-gas adsorption. The effect of compaction was also assessed. RM powder exhibited a moderate Brunauer-Emmet-Teller (BET)-SSA and is mostly a mesoporous (large mesopores, 200-500 Å) and a macroporous material. Compaction affected the macro and large, but not the fine, mesopores. Among the fluids, CaCl2 and acetic acid induced notable and opposing changes in RM microstructural characteristics. CaCl2 decreased SSA and suppressed fine mesoporosity, whereas acetic acid greatly enhanced them. Fractal analysis further indicated increasing surface roughness and heterogeneity of pore structure during acid exposure, altogether envisaging an improvement of adsorption capacity and a decrease of permeability of the RM.

A nanobuffer reporter library for fine-scale imaging and perturbation of endocytic organelles

PubMed Central

Wang, Chensu; Wang, Yiguang; Li, Yang; Bodemann, Brian; Zhao, Tian; Ma, Xinpeng; Huang, Gang; Hu, Zeping; DeBerardinis, Ralph J.; White, Michael A.; Gao, Jinming

2015-01-01

Endosomes, lysosomes and related catabolic organelles are a dynamic continuum of vacuolar structures that impact a number of cell physiological processes such as protein/lipid metabolism, nutrient sensing and cell survival. Here we develop a library of ultra-pH-sensitive fluorescent nanoparticles with chemical properties that allow fine-scale, multiplexed, spatio-temporal perturbation and quantification of catabolic organelle maturation at single organelle resolution to support quantitative investigation of these processes in living cells. Deployment in cells allows quantification of the proton accumulation rate in endosomes; illumination of previously unrecognized regulatory mechanisms coupling pH transitions to endosomal coat protein exchange; discovery of distinct pH thresholds required for mTORC1 activation by free amino acids versus proteins; broad-scale characterization of the consequence of endosomal pH transitions on cellular metabolomic profiles; and functionalization of a context-specific metabolic vulnerability in lung cancer cells. Together, these biological applications indicate the robustness and adaptability of this nanotechnology-enabled ‘detection and perturbation' strategy. PMID:26437053

Schedule of Spermatogenesis in the Pulmonate Snail Helix aspersa, with Special Reference to Histone Transition

PubMed Central

Bloch, David P.; Hew, Howard Y. C.

1960-01-01

The schedule of spermatogenesis is determined from the times necessary for cells labeled with tritium thymidine during premeiotic DNA synthesis to pass through the successive spermatogenic stages. A transition from a typically somatic histone rich in lysine, to a histone rich in arginine is shown to occur during spermatid stages. A later shift to a protamine is observed in the maturing sperm. These changes are characterized by the use of in situ staining methods. The transition to an arginine-rich histone is accompanied by incorporation of tritium-labeled arginine, hence reflects synthesis of new protein. Comparison of the timing of arginine and thymidine incorporation, and independent measurements of DNA, show that in contrast to the case of premitotic chromosome duplication, the histone synthesis in the spermatid is unaccompanied by DNA synthesis. During the initial histone change, fine filaments are formed within the nucleus, which aggregate to form lamellae. This fine structure is lost during maturation of the sperm. PMID:13801496

Fine Structure in Helium-like Fluorine by Fast-Beam Laser Spectroscopy

NASA Astrophysics Data System (ADS)

Myers, E. G.; Thompson, J. K.; Silver, J. D.

1998-05-01

With the aim of providing an additional precise test of higher-order corrections to high precision calculations of fine structure in helium and helium-like ions(T. Zhang, Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 77), 1715 (1996)., a measurement of the 2^3P_2,F - 2^3P_1,F' fine structure in ^19F^7+ is in progress. The method involves doppler-tuned laser spectroscopy using a CO2 laser on a foil-stripped fluorine ion beam. We aim to achieve a higher precision, compared to an earlier measurement(E.G. Myers, P. Kuske, H.J. Andrae, I.A. Armour, H.A. Klein, J.D. Silver, and E. Traebert, Phys. Rev. Lett. 47), 87 (1981)., by using laser beams parallel and anti-parallel to the ion beam, to obtain partial cancellation of the doppler shift(J.K. Thompson, D.J.H. Howie and E.G. Myers, Phys. Rev. A 57), 180 (1998).. A calculation of the hyperfine structure, allowing for relativistic, QED and nuclear size effects, will be required to obtain the ``hyperfine-free'' fine structure interval from the measurements.

Doppler-free spectroscopy of the atomic rubidium fine structure using ultrafast spatial coherent control method

NASA Astrophysics Data System (ADS)

Kim, Minhyuk; Kim, Kyungtae; Lee, Woojun; Kim, Hyosub; Ahn, Jaewook

2017-04-01

Spectral programming solutions for the ultrafast spatial coherent control (USCC) method to resolve the fine-structure energy levels of atomic rubidium are reported. In USCC, a pair of counter-propagating ultrashort laser pulses are programmed to make a two-photon excitation pattern specific to particular transition pathways and atom species, thus allowing the involved transitions resolvable in space simultaneously. With a proper spectral phase and amplitude modulation, USCC has been also demonstrated for the systems with many intermediate energy levels. Pushing the limit of system complexity even further, we show here an experimental demonstration of the rubidium fine-structure excitation pattern resolvable by USCC. The spectral programming solution for the given USCC is achieved by combining a double-V-shape spectral phase function and a set of phase steps, where the former distinguishes the fine structure and the latter prevents resonant transitions. The experimental results will be presented along with its application in conjunction with the Doppler-free frequency-comb spectroscopy for rubidium hyperfine structure measurements. Samsung Science and Technology Foundation [SSTFBA1301-12].

Characterization of structures of the Nankai Trough accretionary prism from integrated analyses of LWD log response, resistivity images and clay mineralogy of cuttings: Expedition 338 Site C0002

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Schleicher, Anja

2014-05-01

The objective of our research is a detailed characterization of structures on the basis of LWD oriented images and logs,and clay mineralogy of cuttings from Hole C0002F of the Nankai Trough accretionary prism. Our results show an integrated interpretation of structures derived from borehole images, petrophysical characterization on LWD logs and cuttings mineralogy. The geometry of the structure intersected at Hole C0002F has been characterized by the interpretation of oriented borehole resistivity images acquired during IODP Expedition 338. The characterization of structural features, faults and fracture zones is based on a detailed post-cruise interpretation of bedding and fractures on borehole images and also on the analysis of Logging While Drilling (LWD) log response (gamma radioactivity, resistivity and sonic logs). The interpretation and complete characterization of structures (fractures, fracture zones, fault zones, folds) was achieved after detailed shorebased reprocessing of resistivity images, which allowed to enhance bedding and fracture's imaging for geometry and orientation interpretation. In order to characterize distinctive petrophysical properties based on LWD log response, it could be compared with compositional changes derived from cuttings analyses. Cuttings analyses were used to calibrate and to characterize log response and to verify interpretations in terms of changes in composition and texture at fractures and fault zones defined on borehole images. Cuttings were taken routinely every 5 m during Expedition 338, indicating a clay-dominated lithology of silty claystone with interbeds of weakly consolidated, fine sandstones. The main mineralogical components are clay minerals, quartz, feldspar and calcite. Selected cuttings were taken from areas of interest as defined on LWD logs and images. The clay mineralogy was investigated on the <2 micron clay-size fraction, with special focus on smectite and illite minerals. Based on X-ray diffraction analysis measured at room temperature and a relative humidity of ~30%, we compared the shape and size of illite and smectite, as well as their water content and their polytypes. The comparison of cuttings mineralogy with logging while drilling (LWD) data allowed us to characterize structural, petrophysical and mineralogical properties at fracture and fault zones. We also analyzed the relationship between deformation structures and compositional and mineralogical changes. We established a correlation between observed results on clay mineralogy and log responses in relation with the structures and trends characterized on logging data. In general, the log data provide a good correlation with the actual mineralogy and the relative abundance of clay. In particular we analyzed trends characterized by smectite water layers as indication of compaction. These trends were correlated with log response (on sonic velocity) within Unit IV. Our results show the integration of logging data and cutting sample analyses as a valuable tool for characterization of petrophysical and mineralogical changes of the structures of the Nankai accretionary prism.

Soft X-ray characterization technique for Li batteries under operating conditions.

PubMed

Petersburg, Cole F; Daniel, Robert C; Jaye, Cherno; Fischer, Daniel A; Alamgir, Faisal M

2009-09-01

O K-edge and Co L-edge near-edge X-ray absorption fine structure has been used to examine the cathode of an intact solid-state lithium ion battery. The novel technique allowed for the simultaneous acquisition of partial electron yield and fluorescence yield data during the first charge cycle of a LiCoO(2)-based battery below the intercalation voltage. The chemical environments of oxygen and cobalt at the surface are shown to differ chemically from those in the bulk. The present design enables a wide variety of in situ spectroscopies, microscopies and scattering techniques.

Stepwise Bay Annulation of Indigo for the Synthesis of Desymmetrized Electron Acceptors and Donor–Acceptor Constructs

DOE PAGES

Kolaczkowski, Matthew A.; He, Bo; Liu, Yi

2016-10-10

In this work, a selective stepwise annulation of indigo has been demonstrated as a means of providing both monoannulated and differentially double-annulated indigo derivatives. Disparate substitution of the electron accepting bay-annulated indigo system allows for fine control over both the electronic properties as well as donor-acceptor structural architectures. Optical and electronic properties were characterized computationally as well as through UV-vis absorption spectroscopy and cyclic voltammetry. Finally, this straightforward method provides a modular approach for the design of indigo-based materials with tailored optoelectronic properties.

Characterization of fossil remains using XRF, XPS and XAFS spectroscopies

NASA Astrophysics Data System (ADS)

Zougrou, I. M.; Katsikini, M.; Pinakidou, F.; Brzhezinskaya, M.; Papadopoulou, L.; Vlachos, E.; Tsoukala, E.; Paloura, E. C.

2016-05-01

Synchrotron radiation micro-X-Ray Fluorescence (μ-XRF), X-ray photoelectron (XPS) and X-ray Absorption Fine Structure (XAFS) spectroscopies are applied for the study of paleontological findings. More specifically the costal plate of a gigantic terrestrial turtle Titanochelon bacharidisi and a fossilized coprolite of the cave spotted hyena Crocuta crocuta spelaea are studied. Ca L 2,3-edge NEXAFS and Ca 2p XPS are applied for the identification and quantification of apatite and Ca containing minerals. XRF mapping and XAFS are employed for the study of the spatial distribution and speciation of the minerals related to the deposition environment.

Unravelling the hidden ancestry of American admixed populations.

PubMed

Montinaro, Francesco; Busby, George B J; Pascali, Vincenzo L; Myers, Simon; Hellenthal, Garrett; Capelli, Cristian

2015-03-24

The movement of people into the Americas has brought different populations into contact, and contemporary American genomes are the product of a range of complex admixture events. Here we apply a haplotype-based ancestry identification approach to a large set of genome-wide SNP data from a variety of American, European and African populations to determine the contributions of different ancestral populations to the Americas. Our results provide a fine-scale characterization of the source populations, identify a series of novel, previously unreported contributions from Africa and Europe and highlight geohistorical structure in the ancestry of American admixed populations.

Mechanical energy storage performance of an aluminum fumarate metal–organic framework† †Electronic supplementary information (ESI) available: Experimental procedures, X-ray diffraction, and molecular simulation. See DOI: 10.1039/c5sc02794b

PubMed Central

Vanduyfhuys, Louis; Alvarez, Elsa; Rodriguez, Julien; Itié, Jean-Paul; Fabry, Paul; Guillou, Nathalie; Devic, Thomas; Beurroies, Isabelle; Llewellyn, Philip L.; Van Speybroeck, Veronique; Serre, Christian; Maurin, Guillaume

2016-01-01

The aluminum fumarate MOF A520 or MIL-53–FA is revealed to be a promising material for mechanical energy-related applications with performances in terms of work and heat energies which surpass those of any porous solids reported so far. Complementary experimental and computational tools are deployed to finely characterize and understand the pressure-induced structural transition at the origin of these unprecedented levels of performance. PMID:29861993

Designing, producing, and constructing fine-graded hot mix asphalt on Illinois roadways.

DOT National Transportation Integrated Search

2015-04-01

Fine-graded (F-G) asphalt concrete mixtures are composed of an aggregate structure in which the fine fraction controls the : load-carrying capacity of the mix. Other states have reported benefits in using F-G mixtures, including improved compaction, ...

Fungal biomineralization of montmorillonite and goethite to short-range-ordered minerals

NASA Astrophysics Data System (ADS)

Li, Huan; Hu, Shuijin; Polizzotto, Matthew L.; Chang, Xiaoli; Shen, Qirong; Ran, Wei; Yu, Guanghui

2016-10-01

Highly reactive nano-scale minerals, e.g., short-range-ordered minerals (SROs) and other nanoparticles, play an important role in soil carbon (C) retention. Yet, the mechanisms that govern biomineralization from bulk minerals to highly reactive nano-scale minerals remain largely unexplored, which critically hinders our efforts toward managing nano-scale minerals for soil C retention. Here we report the results from a study that explores structural changes during Aspergillus fumigatus Z5 transformation of montmorillonite and goethite to SROs. We examined the morphology and structure of nano-scale minerals, using high-resolution transmission electron microscopy, time-resolved solid-state 27Al and 29Si NMR, and Fe K-edge X-ray absorption fine structure spectroscopy combined with two dimensional correlation spectroscopy (2D COS) analysis. Our results showed that after a 48-h cultivation of montmorillonite and goethite with Z5, new biogenic intracellular and extracellular reactive nano-scale minerals with a size of 3-5 nm became abundant. Analysis of 2D COS further suggested that montmorillonite and goethite were the precursors of the dominant biogenic nano-scale minerals. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectra and their deconvolution results demonstrated that during fungus Z5 growth, carboxylic C (288.4-289.1 eV) was the dominant organic group, accounting for approximately 34% and 59% in the medium and aggregates, respectively. This result suggested that high percentage of the production of organic acids during the growth of Z5 was the driving factor for structural changes during biomineralization. This is, to the best of our knowledge, the first report of the structural characterization of nano-scale minerals by 2D COS, highlighting its potential to elucidate biomineralization pathways and thus identify the precursors of nano-scale minerals.

Applications of x ray absorption fine structure to the in situ study of the effect of cobalt in nickel hydrous oxide electrodes for fuel cells and rechargeable batteries

NASA Technical Reports Server (NTRS)

Kim, Sunghyun; Tryk, Donald A.; Scherson, Daniel A.; Antonio, Mark R.

1993-01-01

Electronic and structural aspects of composite nickel-cobalt hydrous oxides have been examined in alkaline solutions using in situ X-ray absorption fine structure (XAFS). The results obtained have indicated that cobalt in this material is present as cobaltic ions regardless of the oxidation state of nickel in the lattice. Furthermore, careful analysis of the Co K-edge Extended X-ray absorption fine structure data reveals that the co-electrodeposition procedure generates a single phase, mixed metal hydrous oxide, in which cobaltic ions occupy nickel sites in the NiO2 sheet-like layers and not two intermixed phases each consisting of a single metal hydrous oxide.

Variations in the fine-structure constant constraining gravity theories

NASA Astrophysics Data System (ADS)

Bezerra, V. B.; Cunha, M. S.; Muniz, C. R.; Tahim, M. O.; Vieira, H. S.

2016-08-01

In this paper, we investigate how the fine-structure constant, α, locally varies in the presence of a static and spherically symmetric gravitational source. The procedure consists in calculating the solution and the energy eigenvalues of a massive scalar field around that source, considering the weak-field regime. From this result, we obtain expressions for a spatially variable fine-structure constant by considering suitable modifications in the involved parameters admitting some scenarios of semi-classical and quantum gravities. Constraints on free parameters of the approached theories are calculated from astrophysical observations of the emission spectra of a white dwarf. Such constraints are finally compared with those obtained in the literature.

Fine Structure Study of the Plasma Coatings B4C-Ni-P

NASA Astrophysics Data System (ADS)

Kornienko, E. E.; Bezrukova, V. A.; Kuz'min, V. I.; Lozhkin, V. S.; Tutunkova, M. K.

2017-12-01

The article considers structure of coatings formed of the B4C-Ni-P powder. The coatings were deposited using air-plasma spraying with the unit for annular injection of powder. The pipes from steel 20 (0.2 % C) were used as a substrate. The structure and phase composition of the coatings were studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. It is shown that high-density composite coatings consisting of boron carbide particles distributed in the nickel boride metal matrix are formed using air-plasma spraying. The areas with round inclusions characterized by the increased amount of nickel, phosphorus and boron are located around the boron carbide particles. Boron oxides and nickel oxides are also present in the coatings. Thin interlayers with amorphous-crystalline structure are formed around the boron carbide particles. The thickness of these interlayers does not exceed 1 μm. The metal matrix material represents areas with nanocrystalline structure and columnar crystals.

Fine Structure of Diffuse Scattering Rings in Al-Li-Cu Quasicrystal: A Comparative X-ray and Electron Diffraction Study

NASA Astrophysics Data System (ADS)

Donnadieu, P.; Dénoyer, F.

1996-11-01

A comparative X-ray and electron diffraction study has been performed on Al-Li-Cu icosahedral quasicrystal in order to investigate the diffuse scattering rings revealed by a previous work. Electron diffraction confirms the existence of rings but shows that the rings have a fine structure. The diffuse aspect on the X-ray diffraction patterns is then due to an averaging effect. Recent simulations based on the model of canonical cells related to the icosahedral packing give diffractions patterns in agreement with this fine structure effect. Nous comparons les diagrammes de diffraction des rayon-X et des électrons obtenus sur les mêmes échantillons du quasicristal icosaèdrique Al-Li-Cu. Notre but est d'étudier les anneaux de diffusion diffuse mis en évidence par un travail précédent. Les diagrammes de diffraction électronique confirment la présence des anneaux mais ils montrent aussi que ces anneaux possèdent une structure fine. L'aspect diffus des anneaux révélés par la diffraction des rayons X est dû à un effet de moyenne. Des simulations récentes basées sur la décomposition en cellules canoniques de l'empilement icosaédrique produisent des diagrammes de diffraction en accord avec ces effects de structure fine.

Local Fine Structural Insight into Mechanism of Electrochemical Passivation of Titanium.

PubMed

Wang, Lu; Yu, Hongying; Wang, Ke; Xu, Haisong; Wang, Shaoyang; Sun, Dongbai

2016-07-20

Electrochemically formed passive film on titanium in 1.0 M H2SO4 solution and its thickness, composition, chemical state, and local fine structure are examined by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure. AES analysis reveals that the thickness and composition of oxide film are proportional to the reciprocal of current density in potentiodynamic polarization. XPS depth profiles of the chemical states of titanium exhibit the coexistence of various valences cations in the surface. Quantitative X-ray absorption near edge structure analysis of the local electronic structure of the topmost surface (∼5.0 nm) shows that the ratio of [TiO2]/[Ti2O3] is consistent with that of passivation/dissolution of electrochemical activity. Theoretical calculation and analysis of extended X-ray absorption fine structure spectra at Ti K-edge indicate that both the structures of passivation and dissolution are distorted caused by the appearance of two different sites of Ti-O and Ti-Ti. And the bound water in the topmost surface plays a vital role in structural disorder confirmed by XPS. Overall, the increase of average Ti-O coordination causes the electrochemical passivation, and the dissolution is due to the decrease of average Ti-Ti coordination. The structural variations of passivation in coordination number and interatomic distance are in good agreement with the prediction of point defect model.

Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization

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

Germann, Matthias; Willitsch, Stefan, E-mail: stefan.willitsch@unibas.ch

2016-07-28

We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O{sub 2} reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ionsmore » produced by photoionization.« less

Extraction and characterization of pectins from primary cell walls of edible açaí (Euterpe oleraceae) berries, fruits of a monocotyledon palm.

PubMed

Cantu-Jungles, Thaisa Moro; Iacomini, Marcello; Cipriani, Thales R; Cordeiro, Lucimara M C

2017-02-20

Açaí berries (Euterpe oleracea) are greatly consumed in Brazil and exported to other countries as a nutritional supplement, due to health benefits attributed to its consumption. However, the complete chemical structure of bioactive polysaccharides was not fully elucidated yet. In this work, we characterize pectic polysaccharides from açaí berries through monosaccharide composition, HPSEC, methylation and 13 C and 1 H/ 13 C HSQC-DEPT-NMR analyses. A highly methoxylated homogalacturonan with a DM of 88% and Mw of 22kDa together with small amounts of a mannoglucan were found. Moreover, a type II arabinogalactan (Mw=45kDa) containing a backbone with high portions of 6-O-linked and 3,6-O-linked Galp chains rather than 3-O-linked Galp was also isolated and structurally characterized. The type II arabinogalactan was found as a side chain of a type I rhamnogalacturonan. These findings contribute to correlate the fine chemical structure with the previously reported action of açaí polysaccharides on innate immune response. Moreover, from the taxonomic point of view, the results bring new information about polysaccharide composition of primary cell walls of palms (Arecaceae), that despite being commelinid monocots, have a distinct cell wall composition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Sintering Temperature to Physical, Magnetic Properties and Crystal Structure on Permanent Magnet BaFe12O19 Prepared From Mill Scale

NASA Astrophysics Data System (ADS)

Ramlan; Muljadi; Sardjono, Priyo; Gulo, Fakhili; Setiabudidaya, Dedi

2017-07-01

Permanent magnet of Barium hexa Ferrite with formula BaFe12O19 has been made by metallurgy powder method from raw materials : Barium carbonate (BaCO3 E-merck) and Iron Oxide (Fe2O3 from mill scale). Both of raw materials have been mixed with stoichiometry composition by using a ball mill for 24 hours. The fine powder obtained from milling process was formed by using a hydraulic press at pressure 50 MPa and continued with sintering process. The sintering temperature was varied : 1150°C, 1200°C, 1250°C and 1300°C with holding time for 1 hour. The sintered samples were characterized such as : physical properties (bulk density, porosity and shrinkage), magnetic properties (flux density, remanence, coercivity and magnetic saturation) by using VSM and crystal structure by using XRD. According characterization results show that the crystal structure of BaFe12O19 does not change after sintering process, but the grain size tends to increase. The optimum condition is achieved at temperature 1250°C, and at this condition, the sample has characterization such as : bulk density = 4.35 g/cm3, porosity = 1.03% and firing shrinkage = 11.63%, flux density = 681.1 Gauss, remanence (σr) = 20.78 emu/g, coercivity (Hc) = 2058 Oe and magnetic saturation (σs) 45.16 emu/g.

Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

NASA Astrophysics Data System (ADS)

Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

2016-08-01

The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape. Overall, the study demonstrates a substantial value of polarimetric data for improving aerosol characterization.

Characterizing the spatial structure of endangered species habitat using geostatistical analysis of IKONOS imagery

USGS Publications Warehouse

Wallace, C.S.A.; Marsh, S.E.

2005-01-01

Our study used geostatistics to extract measures that characterize the spatial structure of vegetated landscapes from satellite imagery for mapping endangered Sonoran pronghorn habitat. Fine spatial resolution IKONOS data provided information at the scale of individual trees or shrubs that permitted analysis of vegetation structure and pattern. We derived images of landscape structure by calculating local estimates of the nugget, sill, and range variogram parameters within 25 ?? 25-m image windows. These variogram parameters, which describe the spatial autocorrelation of the 1-m image pixels, are shown in previous studies to discriminate between different species-specific vegetation associations. We constructed two independent models of pronghorn landscape preference by coupling the derived measures with Sonoran pronghorn sighting data: a distribution-based model and a cluster-based model. The distribution-based model used the descriptive statistics for variogram measures at pronghorn sightings, whereas the cluster-based model used the distribution of pronghorn sightings within clusters of an unsupervised classification of derived images. Both models define similar landscapes, and validation results confirm they effectively predict the locations of an independent set of pronghorn sightings. Such information, although not a substitute for field-based knowledge of the landscape and associated ecological processes, can provide valuable reconnaissance information to guide natural resource management efforts. ?? 2005 Taylor & Francis Group Ltd.

Evaluation of Methods for Physical Characterization of the Fine Particle Emissions from Two Residential Wood Combustion Appliances

EPA Science Inventory

The fine particulate matter (PM) emissions from a U. S. certified non-catalytic wood stove and a zero clearance fireplace burning Quercus rubra L. (northern red oak) and Pseudotsuga menziesii (Douglas fir) cordwood each at two different moisture levels were determined. Emission t...

DEVELOPMENT OF A NEW MOBILE LABORATORY FOR CHARACTERIZATION OF THE FINE PARTICULATE EMISSIONS FROM HEAVY-DUTY DIESEL TRUCKS.

EPA Science Inventory

This paper describes the development of a new mobile laboratory for the determination of the fine particle and gaseous emissions from a Class 8 diesel tractor-trailer research vehicle. The new laboratory (Diesel Emissions Aerosol Laboratory or DEAL) incorporates plume sampling ca...

CHARACTERIZATION OF FINE PARTICLE ASSOCIATED ORGANIC COMPOUNDS: INTERLABORATORY COMPARISON AND DEVELOPMENT OF STANDARD REFERENCE MATERIALS

EPA Science Inventory

Organic chemicals adsorbed to fine particulate matter (PM) in the ambient air account for a major component of the mass and include source tracers as well as toxic compounds that may contribute to adverse human health effects. The US EPA has established a PM 2.5 research progr...

Characterization of the fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge generated by the stainless steelmaking industry.

PubMed

Majuste, Daniel; Mansur, Marcelo Borges

2008-05-01

The argon oxygen decarburization with lance (AOD-L) sludge generated by the stainless steelmaking industry is a hazardous waste due to the presence of chromium. While its coarse fraction is usually recycled into the own industrial process, the fine fraction is normally disposed in landfills. Techniques such as briquetting or magnetic separation were found to be inadequate to treat it for reuse purposes. So, in this work, the fine fraction of the AOD-L sludge was characterized aiming to find alternative methods to treat it. This sludge consists of a fine powder (mean diameter of 1 microm) containing 34 +/- 2% (w/w) of iron, 10.2 +/- 0.9% (w/w) of chromium and 1.4 +/- 0.1% (w/w) of nickel. The main crystalline phases identified in this study were chromite (FeCr(2)O(4)), magnetite (Fe(3)O(4)), hematite (Fe(2)O(3)) and calcite (CaCO(3)). In the digestion tests, the addition of HClO(4) has favored the dissolution of chromite which is a very stable oxide in aqueous media. Nickel was found in very fine particles, probably in the metallic form or associated with iron and oxygen. The sludge was classified as hazardous waste, so its disposal in landfills should be avoided.

a Measurement of the Fine Structure Constant

NASA Astrophysics Data System (ADS)

Hensley, Joel M.; Wicht, Andreas; Sarajlic, Edina; Chu, Steven

2002-06-01

Using an atom interferometer method, we measure the recoil velocity of cesium due to the coherent scattering of a photon. This measurement is used to obtain a preliminary value of ħ/MCs and the fine structure constant, α, with an uncertainty Δα/α = 7.3 × 10-9.

Geometrical Properties of Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Cremades, Hebe; Bothmer, Volker

Based on the SOHO/LASCO dataset, a collection of "structured" coronal mass ejections (CMEs) has been compiled within the period 1996-2002, in order to analyze their three-dimensional configuration. These CME events exhibit white-light fine structures, likely indicative of their possible 3D topology. From a detailed investigation of the associated low coronal and photospheric source regions, a generic scheme has been deduced, which considers the white-light topology of a CME projected in the plane of the sky as being primarily dependent on the orientation and position of the source region's neutral line on the solar disk. The obtained results imply that structured CMEs are essentially organized along a symmetry axis, in a cylindrical manner. The measured dimensions of the cylinder's base and length yield a ratio of 1.6. These CMEs seem to be better approximated by elliptic cones, rather than by the classical ice cream cone, characterized by a circular cross section.

The (111) Surface of NaAu 2. Structure, Composition, and Stability

DOE PAGES

Kwolek, Emma J.; Widmer, Roland; Gröning, Oliver; ...

2014-12-17

The (111) surface of single-crystal NaAu 2 is a model for catalytically active, powdered NaAu 2. We prepare and characterize this surface with a broad suite of techniques. Preparation in ultrahigh vacuum consists of the traditional approach of ion bombardment (to remove impurities) and thermal annealing (to restore surface order). Both of these steps cause loss of sodium (Na), and repeated treatments eventually trigger conversion of the surface and near-surface regions to crystalline gold. The bulk has a limited ability to repopulate the surface Na. Under conditions where Na depletion is minimized, electron diffraction patterns are consistent with the bulk-terminatedmore » structure, and scanning tunneling microscopy reveals mesa-like features with lateral dimensions of a few tens of nanometers. The tops of the mesas do not possess fine structure characteristic of a periodic lattice, suggesting that the surface layer is disordered under the conditions of these experiments.« less

Palm Oil Fuel Ash (POFA) and Eggshell Powder (ESP) as Partial Replacement for Cement in Concrete

NASA Astrophysics Data System (ADS)

Ezdiani Mohamad, Mazizah; Mahmood, Ali A.; Min, Alicia Yik Yee; Nur Nadhira A., R.

2018-03-01

This study is an attempt to partially replace Ordinary Portland cement (OPC) in concrete with palm oil fuel ash (POFA) and eggshell powder (ESP). The mix proportions of POFA and ESP were varied at 10% of cement replacement and compared with OPC concrete as control specimen. The fineness of POFA is characterized by passing through 300 μm sieve and ESP by passing through 75 μm sieve. Compressive strength testing was conducted on concrete specimens to determine the optimum mix proportion of POFA and ESP. Generally the compressive strength of OPC concrete is higher compared to POFA-ESP concrete. Based on the results of POFA-ESP concrete overall, it shows that the optimum mix proportion of concrete is 6%POFA:4% ESP achieved compressive strength of 38.60 N/mm2 at 28 days. The compressive strength of OPC concrete for the same period was 42.37 N/mm2. Higher water demand in concrete is needed due to low fineness of POFA that contributing to low compressive strength of POFA-ESP concrete. However, the compressive strength and workability of the POFA-ESP concrete were within the ranges typically encountered in regular concrete mixtures indicating the viability of this replacement procedure for structural and non-structural applications.

Photopatterned materials in bioanalytical microfluidic technology

PubMed Central

Tentori, Augusto M.; Herr, Amy E.

2011-01-01

Microfluidic technologies are playing an increasingly important role in biological inquiry. Sophisticated approaches to the microanalysis of biological specimens rely, in part, on the fine fluid and material control offered by microtechnology, as well as a sufficient capacity for systems integration. A suite of techniques that utilize photopatterning of polymers on fluidic surfaces, within fluidic volumes, and as primary device structures underpins recent technological innovation in bioanalysis. Well-characterized photopatterning approaches enable previously fabricated or commercially fabricated devices to be customized by the user in a straight-forward manner, making the tools accessible to laboratories that do not focus on microfabrication technology innovation. In this review of recent advances, we summarize reported microfluidic devices with photopatterned structures and regions as platforms for a diverse set of biological measurements and assays. PMID:21857772

NASAL FILTERING OF FINE PARTICLES IN CHILDREN VS. ADULTS

EPA Science Inventory

Nasal efficiency for removing fine particles may be affected by developmental changes in nasal structure associated with age. In healthy Caucasian children (age 6-13, n=17) and adults (age 18-28, n=11) we measured the fractional deposition (DF) of fine particles (1 and 2um MMAD)...

Fine Structure of Dark Energy and New Physics

DOE PAGES

Jejjala, Vishnu; Kavic, Michael; Minic, Djordje

2007-01-01

Following our recent work on the cosmological constant problem, in this letter we make a specific proposal regarding the fine structure (i.e., the spectrum) of dark energy. The proposal is motivated by a deep analogy between the blackbody radiation problem, which led to the development of quantum theory, and the cosmological constant problem, for which we have recently argued calls for a conceptual extension of the quantum theory. We argue that the fine structure of dark energy is governed by a Wien distribution, indicating its dual quantum and classical nature. We discuss observational consequences of such a picture of darkmore » energy and constrain the distribution function.« less

Quantum-gravity predictions for the fine-structure constant

NASA Astrophysics Data System (ADS)

Eichhorn, Astrid; Held, Aaron; Wetterich, Christof

2018-07-01

Asymptotically safe quantum fluctuations of gravity can uniquely determine the value of the gauge coupling for a large class of grand unified models. In turn, this makes the electromagnetic fine-structure constant calculable. The balance of gravity and matter fluctuations results in a fixed point for the running of the gauge coupling. It is approached as the momentum scale is lowered in the transplanckian regime, leading to a uniquely predicted value of the gauge coupling at the Planck scale. The precise value of the predicted fine-structure constant depends on the matter content of the grand unified model. It is proportional to the gravitational fluctuation effects for which computational uncertainties remain to be settled.

Excitonic fine-structure splitting in telecom-wavelength InAs/GaAs quantum dots: Statistical distribution and height-dependence

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

Goldmann, Elias, E-mail: goldmann@itp.uni-bremen.de; Barthel, Stefan; Florian, Matthias

The variation of the excitonic fine-structure splitting is studied for semiconductor quantum dots under the influence of a strain-reducing layer, utilized to shift the emission wavelength of the excitonic transition into the telecom-wavelength regime of 1.3–1.5 μm. By means of a sp{sup 3}s{sup *}-tight-binding model and configuration interaction, we calculate wavelength shifts and fine-structure splittings for various quantum dot geometries. We find the splittings remaining small and even decreasing with strain-reducing layer composition for quantum dots with large height. Combined with an observed increased emission efficiency, the applicability for generation of entanglement photons is persistent.

Characterization of Synthetic and Natural Manganese Oxides as Martian Analogues

NASA Technical Reports Server (NTRS)

Fox, V. K.; Arvidson, R. E.; Jolliff, B. L.; Carpenter, P. K.; Catalano, J. G.; Hinkle, M. A. G.; Morris, R. V.

2015-01-01

Recent discoveries of highly concentrated manganese oxides in Gale Crater and on the rim of Endeavour Crater by the Mars Science Laboratory Curiosity and Mars Exploration Rover Opportunity, respectively, imply more highly oxidizing aqueous conditions than previously recognized. Manganese oxides are a significant environmental indicator about ancient aqueous conditions, provided the phases can be characterized reliably. Manganese oxides are typically fine-grained and poorly crystalline, making the mineral structures difficult to determine, and they generally have very low visible reflectance with few distinctive spectral features in the visible to near infrared, making them a challenge for interpretation from remote sensing data. Therefore, these recent discoveries motivate better characterization using methods available on Mars, particularly visible to near infrared (VNIR) spectroscopy, X-ray diffractometry (XRD), and compositional measurements. Both rovers have complementary instruments in this regard. Opportunity is equipped with its multispectral visible imager, Pancam, and an Alpha Particle X-ray Spectrometer (APXS), and Curiosity has the multispectral Mastcam, ChemCam (laser-induced breakdown spectroscopy and passive spectroscopy), and APXS for in situ characterization, and ChemMin (XRD) for collected samples.

Experimental study of canvas characterization for paintings

NASA Astrophysics Data System (ADS)

Cornelis, Bruno; Dooms, Ann; Munteanu, Adrian; Cornelis, Jan; Schelkens, Peter

2010-02-01

The work described here fits in the context of a larger project on the objective and relevant characterization of paintings and painting canvas through the analysis of multimodal digital images. We captured, amongst others, X-ray images of different canvas types, characterized by a variety of textures and weave patterns (fine and rougher texture; single thread and multiple threads per weave), including raw canvas as well as canvas processed with different primers. In this paper, we study how to characterize the canvas by extracting global features such as average thread width, average distance between successive threads (i.e. thread density) and the spatial distribution of primers. These features are then used to construct a generic model of the canvas structure. Secondly, we investigate whether we can identify different pieces of canvas coming from the same bolt. This is an important element for dating, authentication and identification of restorations. Both the global characteristics mentioned earlier and some local properties (such as deviations from the average pattern model) are used to compare the "fingerprint" of different pieces of cloth coming from the same or different bolts.

Fine structures of wing scales in Sasakia charonda butterflies as photonic crystals.

PubMed

Matejková-Plskova, J; Shiojiri, S; Shiojiri, M

2009-11-01

We investigate the microstructure of scales in the wings of male Sasakia charonda charonda butterflies by scanning electron microscopy with the aid of optical microscopy. Six types of scales are identified: B1, W1 and R1 in brown background yellow spots and red spots, respectively; B2 in iridescent purple-blue and W2 in white pearl, both of which characterize the male and B3 in the wing edges. The B1, W1 and R1 scales are almost the same in structure and the B2 and W2 scales are almost the same. The difference among the B, W and R scales is in species and content of pigment. The B1, W1 and R1 scales have only two layers of cuticle lapped on the ridges. In contrast with them, the B2 and W2 scales have seven multilayers of cuticle piled on the ridge. The multiple interference of light that occurs among these cuticle layers, spaced with air layers, generates the significant iridescence of the B2 and W2 scales. Thus, the characteristic purple-blue of the male wings is ascribed to the combination of the structural and chemical colouration in the B2 scales with melanin. The photonic crystals of these scales may be applicable to fine light manipulators such as reflection elements in laser diodes. B3 has many holes between the ridges and no multilayers of cuticle on the ridges. These structures may play any role in aerodynamically easy flight and/or in drainage of wet wings.

Flow unit modeling and fine-scale predicted permeability validation in Atokan sandstones: Norcan East Kansas

USGS Publications Warehouse

Bhattacharya, S.; Byrnes, A.P.; Watney, W.L.; Doveton, J.H.

2008-01-01

Characterizing the reservoir interval into flow units is an effective way to subdivide the net-pay zone into layers for reservoir simulation. Commonly used flow unit identification techniques require a reliable estimate of permeability in the net pay on a foot-by-foot basis. Most of the wells do not have cores, and the literature is replete with different kinds of correlations, transforms, and prediction methods for profiling permeability in pay. However, for robust flow unit determination, predicted permeability at noncored wells requires validation and, if necessary, refinement. This study outlines the use o f a spreadsheet-based permeability validation technique to characterize flow units in wells from the Norcan East field, Clark County, Kansas, that produce from Atokan aged fine- to very fine-grained quartzarenite sandstones interpreted to have been deposited in brackish-water, tidally dominated restricted tidal-flat, tidal-channel, tidal-bar, and estuary bay environments within a small incised-valley-fill system. The methodology outlined enables the identification of fieldwide free-water level and validates and refines predicted permeability at 0.5-ft (0.15-m) intervals by iteratively reconciling differences in water saturation calculated from wire-line log and a capillary-pressure formulation that models fine- to very fine-grained sandstone with diagenetic clay and silt or shale laminae. The effectiveness of this methodology was confirmed by successfully matching primary and secondary production histories using a flow unit-based reservoir model of the Norcan East field without permeability modifications. The methodologies discussed should prove useful for robust flow unit characterization of different kinds of reservoirs. Copyright ?? 2008. The American Association of Petroleum Geologists. All rights reserved.

A tale of two pectins: Diverse fine structures can result from identical processive PME treatments on similar high DM subtrates

USDA-ARS?s Scientific Manuscript database

The effects of a processive pectin-methylesterase treatment on two different pectins, both possessing a high degree of methylesterification, were investigated. While the starting samples were purportedly very similar in fine structure, and even though the sample-averaged degree of methylesterificati...

Temporal Fine Structure and Applications to Cochlear Implants

ERIC Educational Resources Information Center

Li, Xing

2013-01-01

Complex broadband sounds are decomposed by the auditory filters into a series of relatively narrowband signals, each of which conveys information about the sound by time-varying features. The slow changes in the overall amplitude constitute envelope, while the more rapid events, such as zero crossings, constitute temporal fine structure (TFS).…

Laser Spectroscopy of the Fine-Structure Splitting in the 2^{3}P_{J} Levels of ^{4}He.

PubMed

Zheng, X; Sun, Y R; Chen, J-J; Jiang, W; Pachucki, K; Hu, S-M

2017-02-10

The fine-structure splitting in the 2^{3}P_{J} (J=0, 1, 2) levels of ^{4}He is of great interest for tests of quantum electrodynamics and for the determination of the fine-structure constant α. The 2^{3}P_{0}-2^{3}P_{2} and 2^{3}P_{1}-2^{3}P_{2} intervals are measured by laser spectroscopy of the ^{3}P_{J}-2^{3}S_{1} transitions at 1083 nm in an atomic beam, and are determined to be 31 908 130.98±0.13  kHz and 2 291 177.56±0.19  kHz, respectively. Compared with calculations, which include terms up to α^{5}Ry, the deviation for the α-sensitive interval 2^{3}P_{0}-2^{3}P_{2} is only 0.22 kHz. It opens the window for further improvement of theoretical predictions and an independent determination of the fine-structure constant α with a precision of 2×10^{-9}.

QUIESCENT PROMINENCES IN THE ERA OF ALMA: SIMULATED OBSERVATIONS USING THE 3D WHOLE-PROMINENCE FINE STRUCTURE MODEL

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

Gunár, Stanislav; Heinzel, Petr; Mackay, Duncan H.

2016-12-20

We use the detailed 3D whole-prominence fine structure model to produce the first simulated high-resolution ALMA observations of a modeled quiescent solar prominence. The maps of synthetic brightness temperature and optical thickness shown in the present paper are produced using a visualization method for synthesis of the submillimeter/millimeter radio continua. We have obtained the simulated observations of both the prominence at the limb and the filament on the disk at wavelengths covering a broad range that encompasses the full potential of ALMA. We demonstrate here extent to which the small-scale and large-scale prominence and filament structures will be visible inmore » the ALMA observations spanning both the optically thin and thick regimes. We analyze the relationship between the brightness and kinetic temperature of the prominence plasma. We also illustrate the opportunities ALMA will provide for studying the thermal structure of the prominence plasma from the cores of the cool prominence fine structure to the prominence–corona transition region. In addition, we show that detailed 3D modeling of entire prominences with their numerous fine structures will be important for the correct interpretation of future ALMA observations of prominences.« less

Fine mode aerosol chemistry over a rural atmosphere near the north-east coast of Bay of Bengal in India

NASA Astrophysics Data System (ADS)

Adak, Anandamay; Chatterjee, Abhijit; Ghosh, Sanjay; Raha, Sibaji; Roy, Arindam

2016-07-01

A study was conducted on the chemical characterization of fine mode aerosol or PM2.5 over a rural atmosphere near the coast of Bay of Bengal in eastern India. Samples were collected and analyzed during March 2013 - February 2014. The concentration of PM2.5 was found span over a wide range from as low as 3 µg m-3 to as high as 180 µg m-3. The average concentration of PM2.5 was 62 µg m-3. Maximum accumulation of fine mode aerosol was observed during winter whereas minimum was observed during monsoon. Water soluble ionic species of fine mode aerosol were characterized over this rural atmosphere. In spite of being situated near the coast of Bay of Bengal, we observed significantly higher concentrations for anthropogenic species like ammonium and sulphate. The concentrations of these two species were much higher than the sea-salt aerosols. Ammonium and sulphate contributed around 30 % to the total fine mode aerosols. Even dust aerosol species like calcium also showed higher concentrations. Chloride to sodium ratio was found to be much less than that in standard sea-water indicating strong interaction between sea-salt and anthropogenic aerosols. Use of fertilizers in various crop fields and human and animal wastes significantly increased ammonium in fine mode aerosols. Dust aerosol species were accumulated in the atmosphere which could be due to transport of finer dust species from nearby metropolis or locally generated. Non-sea-sulphate and nitrate showed significant contributions in fine mode aerosols having both local and transported sources. Source apportionment shows prominent emission sources of anthropogenic aerosols from local anthropogenic activities and transported from nearby Kolkata metropolis as well.

Toward a suitable structural analysis of gene delivery carrier based on polycationic carbohydrates by electron transfer dissociation tandem mass spectrometry.

PubMed

Przybylski, Cédric; Benito, Juan M; Bonnet, Véronique; Mellet, Carmen Ortiz; García Fernández, José M

2016-12-15

Polycationic carbohydrates represent an attractive class of biomolecules for several applications and particularly as non viral gene delivery vectors. In this case, the establishment of structure-biological activity relationship requires sensitive and accurate characterization tools to both control and achieve fine structural deciphering. Electrospray-tandem mass spectrometry (ESI-MS/MS) appears as a suitable approach to address these questions. In the study herein, we have investigated the usefulness of electron transfer dissociation (ETD) to get structural data about five polycationic carbohydrates demonstrated as promising gene delivery agents. A particular attention was paid to determine the influence of charge states as well as both fluoranthene reaction time and supplementary activation (SA) on production of charge reduced species, fragmentation yield, varying from 2 to 62%, as well as to obtain the most higher both diversity and intensity of fragments, according to charge states and targeted compounds. ETD fragmentation appeared to be mainly directed toward pending group rather than carbohydrate cyclic scaffold leading to a partial sequencing for building blocks when amino groups are close to carbohydrate core, but allowing to complete structural deciphering of some of them, such as those including dithioureidocysteaminyl group which was not possible with CID only. Such findings clearly highlight the potential to help the rational choice of the suitable analytical conditions, according to the nature of the gene delivery molecules exhibiting polycationic features. Moreover, our ETD-MS/MS approach open the way to a fine sequencing/identification of grafted groups carried on various sets of oligo-/polysaccharides in various fields such as glycobiology or nanomaterials, even with unknown or questionable extraction, synthesis or modification steps. Copyright © 2016 Elsevier B.V. All rights reserved.

Correlated randomness and switching phenomena

NASA Astrophysics Data System (ADS)

Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

2010-08-01

One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

Demonstrating the Uneven Importance of Fine-Scale Forest Structure on Snow Distributions using High Resolution Modeling

NASA Astrophysics Data System (ADS)

Broxton, P. D.; Harpold, A. A.; van Leeuwen, W.; Biederman, J. A.

2016-12-01

Quantifying the amount of snow in forested mountainous environments, as well as how it may change due to warming and forest disturbance, is critical given its importance for water supply and ecosystem health. Forest canopies affect snow accumulation and ablation in ways that are difficult to observe and model. Furthermore, fine-scale forest structure can accentuate or diminish the effects of forest-snow interactions. Despite decades of research demonstrating the importance of fine-scale forest structure (e.g. canopy edges and gaps) on snow, we still lack a comprehensive understanding of where and when forest structure has the largest impact on snowpack mass and energy budgets. Here, we use a hyper-resolution (1 meter spatial resolution) mass and energy balance snow model called the Snow Physics and Laser Mapping (SnowPALM) model along with LIDAR-derived forest structure to determine where spatial variability of fine-scale forest structure has the largest influence on large scale mass and energy budgets. SnowPALM was set up and calibrated at sites representing diverse climates in New Mexico, Arizona, and California. Then, we compared simulations at different model resolutions (i.e. 1, 10, and 100 m) to elucidate the effects of including versus not including information about fine scale canopy structure. These experiments were repeated for different prescribed topographies (i.e. flat, 30% slope north, and south-facing) at each site. Higher resolution simulations had more snow at lower canopy cover, with the opposite being true at high canopy cover. Furthermore, there is considerable scatter, indicating that different canopy arrangements can lead to different amounts of snow, even when the overall canopy coverage is the same. This modeling is contributing to the development of a high resolution machine learning algorithm called the Snow Water Artificial Network (SWANN) model to generate predictions of snow distributions over much larger domains, which has implications for improving land surface models that do not currently resolve or parameterize fine-scale canopy structure. In addition, these findings have implications for understanding the potential of different forest management strategies (i.e. thinning) based on local topography and climate to maximize the amount and retention of snow.

Chemical characterization of the fine particle emissions from commercial aircraft engines during the Aircraft Particle Emissions eXperiment (APEX) 1 to 3

EPA Science Inventory

This paper addresses the need for detailed chemical information on the fine particulate matter (PM2.5) generated by commercial aviation engines. The exhaust plumes of nine engine models were sampled during the three test campaigns of the Aircraft Particle Emissions eXperiment (AP...

Scanning tunneling microscopy of atomically precise graphene nanoribbons exfoliated onto H:Si(100)

NASA Astrophysics Data System (ADS)

Radocea, Adrian; Mehdi Pour, Mohammad; Vo, Timothy; Shekhirev, Mikhail; Sinitskii, Alexander; Lyding, Joseph

Atomically precise graphene nanoribbons (GNRs) are promising materials for next generation transistors due to their well-controlled bandgaps and the high thermal conductivity of graphene. The solution synthesis of graphene nanoribbons offers a pathway towards scalable manufacturing. While scanning tunneling microscopy (STM) can access size scales required for characterization, solvent residue increases experimental difficulty and precludes band-gap determination via scanning tunneling spectroscopy (STS). Our work addresses this challenge through a dry contact transfer method that cleanly transfers solution-synthesized GNRs onto H:Si(100) under UHV using a fiberglass applicator. The semiconducting silicon surface avoids problems with image charge screening enabling intrinsic bandgap measurements. We characterize the nanoribbons using STM and STS. For chevron GNRs, we find a 1.6 eV bandgap, in agreement with computational modeling, and map the electronic structure spatially with detailed spectra lines and current imaging tunneling spectroscopy. Mapping the electronic structure of graphene nanoribbons is an important step towards taking advantage of the ability to form atomically precise nanoribbons and finely tune their properties.

Nanoscale Hollow Spheres: Microemulsion-Based Synthesis, Structural Characterization and Container-Type Functionality

PubMed Central

Gröger, Henriette; Kind, Christian; Leidinger, Peter; Roming, Marcus; Feldmann, Claus

2010-01-01

A wide variety of nanoscale hollow spheres can be obtained via a microemulsion approach. This includes oxides (e.g., ZnO, TiO2, SnO2, AlO(OH), La(OH)3), sulfides (e.g., Cu2S, CuS) as well as elemental metals (e.g., Ag, Au). All hollow spheres are realized with outer diameters of 10−60 nm, an inner cavity size of 2−30 nm and a wall thickness of 2−15 nm. The microemulsion approach allows modification of the composition of the hollow spheres, fine-tuning their diameter and encapsulation of various ingredients inside the resulting “nanocontainers”. This review summarizes the experimental conditions of synthesis and compares them to other methods of preparing hollow spheres. Moreover, the structural characterization and selected properties of the as-prepared hollow spheres are discussed. The latter is especially focused on container-functionalities with the encapsulation of inorganic salts (e.g., KSCN, K2S2O8, KF), biomolecules/bioactive molecules (e.g., phenylalanine, quercetin, nicotinic acid) and fluorescent dyes (e.g., rhodamine, riboflavin) as representative examples. PMID:28883333

High-resolution mapping, characterization, and optimization of autonomously replicating sequences in yeast

PubMed Central

Liachko, Ivan; Youngblood, Rachel A.; Keich, Uri; Dunham, Maitreya J.

2013-01-01

DNA replication origins are necessary for the duplication of genomes. In addition, plasmid-based expression systems require DNA replication origins to maintain plasmids efficiently. The yeast autonomously replicating sequence (ARS) assay has been a valuable tool in dissecting replication origin structure and function. However, the dearth of information on origins in diverse yeasts limits the availability of efficient replication origin modules to only a handful of species and restricts our understanding of origin function and evolution. To enable rapid study of origins, we have developed a sequencing-based suite of methods for comprehensively mapping and characterizing ARSs within a yeast genome. Our approach finely maps genomic inserts capable of supporting plasmid replication and uses massively parallel deep mutational scanning to define molecular determinants of ARS function with single-nucleotide resolution. In addition to providing unprecedented detail into origin structure, our data have allowed us to design short, synthetic DNA sequences that retain maximal ARS function. These methods can be readily applied to understand and modulate ARS function in diverse systems. PMID:23241746

End of the chain? Rugosity and fine-scale bathymetry from existing underwater digital imagery using structure-from-motion (SfM) technology

USGS Publications Warehouse

Storlazzi, Curt; Dartnell, Peter; Hatcher, Gerry; Gibbs, Ann E.

2016-01-01

The rugosity or complexity of the seafloor has been shown to be an important ecological parameter for fish, algae, and corals. Historically, rugosity has been measured either using simple and subjective manual methods such as ‘chain-and-tape’ or complicated and expensive geophysical methods. Here, we demonstrate the application of structure-from-motion (SfM) photogrammetry to generate high-resolution, three-dimensional bathymetric models of a fringing reef from existing underwater video collected to characterize the seafloor. SfM techniques are capable of achieving spatial resolution that can be orders of magnitude greater than large-scale lidar and sonar mapping of coral reef ecosystems. The resulting data provide finer-scale measurements of bathymetry and rugosity that are more applicable to ecological studies of coral reefs than provided by the more expensive and time-consuming geophysical methods. Utilizing SfM techniques for characterizing the benthic habitat proved to be more effective and quantitatively powerful than conventional methods and thus might portend the end of the ‘chain-and-tape’ method for measuring benthic complexity.

Surface microstructure of bitumen characterized by atomic force microscopy.

PubMed

Yu, Xiaokong; Burnham, Nancy A; Tao, Mingjiang

2015-04-01

Bitumen, also called asphalt binder, plays important roles in many industrial applications. It is used as the primary binding agent in asphalt concrete, as a key component in damping systems such as rubber, and as an indispensable additive in paint and ink. Consisting of a large number of hydrocarbons of different sizes and polarities, together with heteroatoms and traces of metals, bitumen displays rich surface microstructures that affect its rheological properties. This paper reviews the current understanding of bitumen's surface microstructures characterized by Atomic Force Microscopy (AFM). Microstructures of bitumen develop to different forms depending on crude oil source, thermal history, and sample preparation method. While some bitumens display surface microstructures with fine domains, flake-like domains, and dendrite structuring, 'bee-structures' with wavy patterns several micrometers in diameter and tens of nanometers in height are commonly seen in other binders. Controversy exists regarding the chemical origin of the 'bee-structures', which has been related to the asphaltene fraction, the metal content, or the crystallizing waxes in bitumen. The rich chemistry of bitumen can result in complicated intermolecular associations such as coprecipitation of wax and metalloporphyrins in asphaltenes. Therefore, it is the molecular interactions among the different chemical components in bitumen, rather than a single chemical fraction, that are responsible for the evolution of bitumen's diverse microstructures, including the 'bee-structures'. Mechanisms such as curvature elasticity and surface wrinkling that explain the rippled structures observed in polymer crystals might be responsible for the formation of 'bee-structures' in bitumen. Despite the progress made on morphological characterization of bitumen using AFM, the fundamental question whether the microstructures observed on bitumen surfaces represent its bulk structure remains to be addressed. In addition, critical technical challenges associated with AFM characterization of bitumen surface structures are discussed, with possible solutions recommended. For future work, combining AFM with other chemical analysis tools that can generate comparable high resolution to AFM would provide an avenue to linking bitumen's chemistry to its microscopic morphological and mechanical properties and consequently benefit the efforts of developing structure-related models for bituminous materials across the different length scales. Copyright © 2015 Elsevier B.V. All rights reserved.

Relaxation of the structure of simple metal ion complexes in aqueous solutions at up to supercritical conditions

USGS Publications Warehouse

Mayanovic, Robert A.; Jayanetti, Sumedha; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2003-01-01

Recently x-ray absorption fine structure (XAFS) studies of various ions in aqueous solutions showed a variation of cation-ligand bond lengths, often coupled with other structure changes, with increasing temperatures. Thus, the variations of the structure of several metal ion complexes with temperature based on observations from the X-ray absorption fine structure (XAFS) studies in the hope that it will stimulate the development of either first- principles theory or molecular dynamics simulations that might adequately describes these results are discussed.

Quantitative characterization of microstructure of asphalt mixtures

DOT National Transportation Integrated Search

2010-10-01

The microstructure of the fine aggregate matrix has a significant influence on the : mechanical properties and evolution of damage in an asphalt mixture. However, very little : work has been done to define and quantitatively characterize the microstr...

Laser characterization of fine aggregate.

DOT National Transportation Integrated Search

2012-12-01

This report describes the results of a research effort to establish the feasibility of using a laser monitoring system to provide real-time data to characterize aggregate properties in a laboratory or field environment. This was accomplished by using...

Characterisation and Processing of Some Iron Ores of India

NASA Astrophysics Data System (ADS)

Krishna, S. J. G.; Patil, M. R.; Rudrappa, C.; Kumar, S. P.; Ravi, B. P.

2013-10-01

Lack of process characterization data of the ores based on the granulometry, texture, mineralogy, physical, chemical, properties, merits and limitations of process, market and local conditions may mislead the mineral processing entrepreneur. The proper implementation of process characterization and geotechnical map data will result in optimized sustainable utilization of resource by processing. A few case studies of process characterization of some Indian iron ores are dealt with. The tentative ascending order of process refractoriness of iron ores is massive hematite/magnetite < marine black iron oxide sands < laminated soft friable siliceous ore fines < massive banded magnetite quartzite < laminated soft friable clayey aluminous ore fines < massive banded hematite quartzite/jasper < massive clayey hydrated iron oxide ore < manganese bearing iron ores massive < Ti-V bearing magnetite magmatic ore < ferruginous cherty quartzite. Based on diagnostic process characterization, the ores have been classified and generic process have been adopted for some Indian iron ores.

Combinatorial selection of molecular conformations and supramolecular synthons in quercetin cocrystal landscapes: a route to ternary solids

PubMed Central

Dubey, Ritesh; Desiraju, Gautam R.

2015-01-01

The crystallization of 28 binary and ternary cocrystals of quercetin with dibasic coformers is analyzed in terms of a combinatorial selection from a solution of preferred molecular conformations and supramolecular synthons. The crystal structures are characterized by distinctive O—H⋯N and O—H⋯O based synthons and are classified as nonporous, porous and helical. Variability in molecular conformation and synthon structure led to an increase in the energetic and structural space around the crystallization event. This space is the crystal structure landscape of the compound and is explored by fine-tuning the experimental conditions of crystallization. In the landscape context, we develop a strategy for the isolation of ternary cocrystals with the use of auxiliary template molecules to reduce the molecular and supramolecular ‘confusion’ that is inherent in a molecule like quercetin. The absence of concomitant polymorphism in this study highlights the selectivity in conformation and synthon choice from the virtual combinatorial library in solution. PMID:26175900

Cobalt Oxide Nanoclusters on Rutile Titania as Bifunctional Units for Water Oxidation Catalysis and Visible Light Absorption: Understanding the Structure-Activity Relationship.

PubMed

Maeda, Kazuhiko; Ishimaki, Koki; Okazaki, Megumi; Kanazawa, Tomoki; Lu, Daling; Nozawa, Shunsuke; Kato, Hideki; Kakihana, Masato

2017-02-22

The structure of cobalt oxide (CoO x ) nanoparticles dispersed on rutile TiO 2 (R-TiO 2 ) was characterized by X-ray diffraction, UV-vis-NIR diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, X-ray absorption fine-structure spectroscopy, and X-ray photoelectron spectroscopy. The CoO x nanoparticles were loaded onto R-TiO 2 by an impregnation method from an aqueous solution containing Co(NO 3 ) 2 ·6H 2 O followed by heating in air. Modification of the R-TiO 2 with 2.0 wt % Co followed by heating at 423 K for 1 h resulted in the highest photocatalytic activity with good reproducibility. Structural analyses revealed that the activity of this photocatalyst depended strongly on the generation of Co 3 O 4 nanoclusters with an optimal distribution. These nanoclusters are thought to interact with the R-TiO 2 surface, resulting in visible light absorption and active sites for water oxidation.

Characterization of Fractures in the Chicxulub Peak Ring: Preliminary Results from IODP/ICDP Expedition 364

NASA Astrophysics Data System (ADS)

McCall, N.; Gulick, S. P. S.; Morgan, J. V.; Hall, B. J.; Jones, L.; Expedition 364 Science Party, I. I.

2017-12-01

During Expedition 364, IODP/ICDP drilled the peak ring of the Chicxulub impact crater at Site M0077, recovering core from 505.7 to 1334.7 mbsf. The core has been imaged via X-ray Computer Tomography (CT) as a noninvasive method to create a 3-dimensional model of the core, providing information on the density and internal structure at a 0.3 mm resolution. Results from the expedition show that from 748 mbsf and deeper the peak ring is largely composed of uplifted and fractured granitic basement rocks originally sourced from approximately 8-10 km depth. Impact crater modeling suggests the peak ring was formed through dynamic collapse of a rebounding central peak within 10 minutes of impact, requiring the target rocks to temporarily behave as a viscous fluid. The newly recovered core provides a rare opportunity to investigate the cratering process, specifically how the granite was weakened, as well as the extent of the hydrothermal system created after the impact. Based on the CT data, we identify four classes of fractures based on their CT facies deforming the granitoids: pervasive fine fractures, discrete fine fractures, discrete filled fractures, and discrete open fractures. Pervasive fine fractures were most commonly found proximal to dikes and impact melt rock. Discrete filled fractures often displayed a cataclastic texture. We present density trends for the different facies and compare these to petrophysical properties (density, NGR, P-wave seismic velocity). Fractured areas have a lower density than the surrounding granite, as do most filled fractures. This reduction suggests that fluid migrating through the peak ring in the wake of the impact either deposited lower density minerals within the fractures and/or altered the original fracture fill. The extent and duration of fluid flow recorded in these fractures will assist in the characterization of the post-impact hydrothermal system. Future work includes combining information from CT images with thin sections and plug samples at similar depths, refinement of CT facies characterization, examining cross-cutting relationships to determine timing constraints of deformation processes, and measurement of the orientation of the fractures.

Local Structure and Anisotropy in the Amorphous Precursor= to Ba-Hexaferrite Thin Films

NASA Astrophysics Data System (ADS)

Snyder, J. E.; Harris, V. G.; Koon, N. C.; Sui, X.; Kryder, M. H.

1996-03-01

Ba-hexaferrite thin-films for recording media applications are commonly fabricated by a two-step process: sputter-deposition of an amorphous precursor, followed by annealing to crystallize the BaFe_12O_19 phase. The magnetic anisotropy of the crystalline films can be either in-plane or perpendicular, depending on the sputtering process used in the first step. However, conventional characterization techniques (x-ray diffraction and TEM) have been unable to observe any structure in the amorphous precursor films. In this study, such films are investigated by PD-EXAFS (polarization-dependent extended x-ray absorption fine structure). An anisotropic local ordered structure is observed around both Fe and Ba atoms in the "amorphous" films. This anisotropic local structure appears to determine the orientation of the fast-growing basal plane directions during crystallization, and thus the directions of the c-axes and the magnetic anisotropy. Results suggest that the structure of the amorphous films consists of networks made up of units of Fe atoms surrounded by their O nearest neighbors, that are connected together. Ba atoms appear to fit into in-between spaces as network-modifiers.

Adequate mathematical modelling of environmental processes

NASA Astrophysics Data System (ADS)

Chashechkin, Yu. D.

2012-04-01

In environmental observations and laboratory visualization both large scale flow components like currents, jets, vortices, waves and a fine structure are registered (different examples are given). The conventional mathematical modeling both analytical and numerical is directed mostly on description of energetically important flow components. The role of a fine structures is still remains obscured. A variety of existing models makes it difficult to choose the most adequate and to estimate mutual assessment of their degree of correspondence. The goal of the talk is to give scrutiny analysis of kinematics and dynamics of flows. A difference between the concept of "motion" as transformation of vector space into itself with a distance conservation and the concept of "flow" as displacement and rotation of deformable "fluid particles" is underlined. Basic physical quantities of the flow that are density, momentum, energy (entropy) and admixture concentration are selected as physical parameters defined by the fundamental set which includes differential D'Alembert, Navier-Stokes, Fourier's and/or Fick's equations and closing equation of state. All of them are observable and independent. Calculations of continuous Lie groups shown that only the fundamental set is characterized by the ten-parametric Galilelian groups reflecting based principles of mechanics. Presented analysis demonstrates that conventionally used approximations dramatically change the symmetries of the governing equations sets which leads to their incompatibility or even degeneration. The fundamental set is analyzed taking into account condition of compatibility. A high order of the set indicated on complex structure of complete solutions corresponding to physical structure of real flows. Analytical solutions of a number problems including flows induced by diffusion on topography, generation of the periodic internal waves a compact sources in week-dissipative media as well as numerical solutions of the same problems are constructed. They include regular perturbed function describing large scale component and a rich family of singular perturbed function corresponding to fine flow components. Solutions are compared with data of laboratory experiments performed on facilities USU "HPC IPMec RAS" under support of Ministry of Education and Science RF (Goscontract No. 16.518.11.7059). Related problems of completeness and accuracy of laboratory and environmental measurements are discussed.

Simple preparation of magnetic field-responsive structural colored Janus particles.

PubMed

Teshima, Midori; Seki, Takahiro; Takeoka, Yukikazu

2018-03-08

We established a simple method for preparing Janus particles displaying different structural colors using submicron-sized fine silica particles and magnetic nanoparticles composed of Fe 3 O 4 . A w/o emulsion is prepared by vortex-stirring a mixed aqueous solution of suspended fine silica particles and magnetic nanoparticles and of hexadecane containing an emulsifier. Subsequent drying of the emulsion on a hot plate using a magnetic stirrer provides a polydisperse particle aggregate displaying two different structural colors according to the ratio of the amount of fine silica particles to the amount of magnetic nanoparticles. This polydisperse particle aggregate can be converted into monodisperse particles simply by using a sieve made of stainless steel. In the presence of a magnet, the monodisperse Janus particles can change their orientation and can switch between two different structural colors.

The fine-structure intervals of (N-14)+ by far-infrared laser magnetic resonance

NASA Technical Reports Server (NTRS)

Brown, John M.; Varberg, Thomas D.; Evenson, Kenneth M.; Cooksy, Andrew L.

1994-01-01

The far-infrared laser magnetic resonance spectra associated with both fine-structure transitions in (N-14)+ in its ground P-3 state have been recorded. This is the first laboratory observation of the J = 1 left arrow 0 transition and its frequency has been determined two orders of magnitude more accurately than previously. The remeasurement of the J = 2 left arrow 1 spectrum revealed a small error in the previous laboratory measurements. The fine-structure splittings (free of hyperfine interactions) determined in this work are (delta)E(sub 10) = 1461.13190 (61) GHz, (delta)E(sub 21) = 2459.38006 (37) GHz. Zero-field transition frequencies which include the effects of hyperfine structure have also been calculated. Refined values for the hyperfine constants and the g(sub J) factors have been obtained.

Dynamical Study of Femtosecond-Laser-Ablated Liquid-Aluminum Nanoparticles Using Spatiotemporally Resolved X-Ray-Absorption Fine-Structure Spectroscopy

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

Oguri, Katsuya; Okano, Yasuaki; Nishikawa, Tadashi

2007-10-19

We study the temperature evolution of aluminum nanoparticles generated by femtosecond laser ablation with spatiotemporally resolved x-ray-absorption fine-structure spectroscopy. We successfully identify the nanoparticles based on the L-edge absorption fine structure of the ablation plume in combination with the dependence of the edge structure on the irradiation intensity and the expansion velocity of the plume. In particular, we show that the lattice temperature of the nanoparticles is estimated from the L-edge slope, and that its spatial dependence reflects the cooling of the nanoparticles during plume expansion. The results reveal that the emitted nanoparticles travel in a vacuum as a condensedmore » liquid phase with a lattice temperature of about 2500 to 4200 K in the early stage of plume expansion.« less

Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

NASA Astrophysics Data System (ADS)

Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

Surfaces of Fluorinated Pyridinium Block Copolymers with Enhanced Antibacterial Activity

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

Krishnan,S.; Ward, R.; Hexemer, A.

2006-01-01

Polystyrene-b-poly(4-vinylpyridine) copolymers were quaternized with 1-bromohexane and 6-perfluorooctyl-1-bromohexane. Surfaces prepared from these polymers were characterized by contact angle measurements, near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy. The fluorinated pyridinium surfaces showed enhanced antibacterial activity compared to their nonfluorinated counterparts. Even a polymer with a relatively low molecular weight pyridinium block showed high antimicrobial activity. The bactericidal effect was found to be related to the molecular composition and organization in the top 2-3 nm of the surface and increased with increasing hydrophilicity and pyridinium concentration of the surface.

The prominent photoinduced voltage effect of as-prepared macroscopically long Ag core/Ni shell nanoheterojunctions.

PubMed

Sun, Jia-Lin; Zhao, Xingchen; Zhu, Jia-Lin

2008-02-27

Macroscopically long Ag core/Ni shell nanoheterojunctions have been well prepared by a dynamic growth approach. The structure characterized in detail by scanning electron microscopy reveals that the Ag nanowire bundles are wrapped in Ni nanoshields and form multicore coaxial cable frames. Notable photoinduced voltage with a fine repeatability, for irradiation with a laser, is exhibited compared with the case for bulk Ag pole/Ni shell heterojunctions and Ag nanowire bundle/bulk Ni heterojunctions. The prominent photoinduced voltage and the substantial metal nanoscale Ohmic interconnects provided by this kind of nanoheterojunction may have a wide range of applications in the future.

Electron microscopy of a Gd-Ba-Cu-O superconductor

NASA Technical Reports Server (NTRS)

Ramesh, R.; Thomas, G.; Meng, R. L.; Hor, P. H.; Chu, C. W.

1989-01-01

An electron microscopy study has been carried out to characterize the microstructure of a sintered Gd-Ba-Cu-O superconductor alloy. The GdBa2Cu3O(7-x) phase in the oxygen annealed sample is orthorhombic, while in the vacuum annealed sample it is tetragonal. It is shown that the details of the fine structure in the 001-line zone axis convergent beam patterns can be used to distinguish between the orthorhombic form and the tetragonal form. In addition to this matrix phase, an amorphous phase is frequently observed at the triple grain junctions. Gd-rich inclusions have been observed inside the matrix phase.

Friction stir weld tools having fine grain structure

DOEpatents

Grant, Glenn J.; Frye, John G.; Kim, Jin Yong; Lavender, Curt A.; Weil, Kenneth Scott

2016-03-15

Tools for friction stir welding can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes by utilizing improved compositions and processes of fabrication. Furthermore, the tools resulting from the improved compositions and processes of fabrication can exhibit better distribution and homogeneity of chemical constituents, greater strength, and/or increased durability. In one example, a friction stir weld tool includes tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter.

A simple approach to hybrid inorganic–organic step-growth hydrogels with scalable control of physicochemical properties and biodegradability† †Electronic supplementary information (ESI) available: Experimental details and characterization data as mentioned in the text. See DOI: 10.1039/c4py01789g Click here for additional data file.

PubMed Central

Alves, F.

2015-01-01

We prepared new and scalable, hybrid inorganic–organic step-growth hydrogels with polyhedral oligomeric silsesquioxane (POSS) network knot construction elements and hydrolytically degradable poly(ethylene glycol) (PEG) di-ester macromonomers by in situ radical-mediated thiol–ene photopolymerization. The physicochemical properties of the gels are fine-tailored over orders of magnitude including functionalization of their interior, a hierarchical gel structure, and biodegradability. PMID:25821524

Adaptive root foraging strategies along a boreal-temperate forest gradient.

PubMed

Ostonen, Ivika; Truu, Marika; Helmisaari, Heljä-Sisko; Lukac, Martin; Borken, Werner; Vanguelova, Elena; Godbold, Douglas L; Lõhmus, Krista; Zang, Ulrich; Tedersoo, Leho; Preem, Jens-Konrad; Rosenvald, Katrin; Aosaar, Jürgen; Armolaitis, Kęstutis; Frey, Jane; Kabral, Naima; Kukumägi, Mai; Leppälammi-Kujansuu, Jaana; Lindroos, Antti-Jussi; Merilä, Päivi; Napa, Ülle; Nöjd, Pekka; Parts, Kaarin; Uri, Veiko; Varik, Mats; Truu, Jaak

2017-08-01

The tree root-mycorhizosphere plays a key role in resource uptake, but also in the adaptation of forests to changing environments. The adaptive foraging mechanisms of ectomycorrhizal (EcM) and fine roots of Picea abies, Pinus sylvestris and Betula pendula were evaluated along a gradient from temperate to subarctic boreal forest (38 sites between latitudes 48°N and 69°N) in Europe. Variables describing tree resource uptake structures and processes (absorptive fine root biomass and morphology, nitrogen (N) concentration in absorptive roots, extramatrical mycelium (EMM) biomass, community structure of root-associated EcM fungi, soil and rhizosphere bacteria) were used to analyse relationships between root system functional traits and climate, soil and stand characteristics. Absorptive fine root biomass per stand basal area increased significantly from temperate to boreal forests, coinciding with longer and thinner root tips with higher tissue density, smaller EMM biomass per root length and a shift in soil microbial community structure. The soil carbon (C) : N ratio was found to explain most of the variability in absorptive fine root and EMM biomass, root tissue density, N concentration and rhizosphere bacterial community structure. We suggest a concept of absorptive fine root foraging strategies involving both qualitative and quantitative changes in the root-mycorrhiza-bacteria continuum along climate and soil C : N gradients. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Characterization of fine volcanic ash from explosive eruption from Sakurajima volcano, South Japan

NASA Astrophysics Data System (ADS)

Nanayama, F.; Furukawa, R.; Ishizuka, Y.; Yamamoto, T.; Geshi, N.; Oishi, M.

2013-12-01

Explosive volcanic eruptions can affect infrastructure and ecosystem by their dispersion of the volcanic particle. Characterization of volcanic particle expelled by explosive eruption is crucial for evaluating for quantitative hazard assessment by future volcanic eruption. Especially for fine volcanic ash less than 64 micron in diameter, it can disperse vast area from the source volcano and be easily remobilized by surface wind and precipitation after the deposition. As fine volcanic ash is not preserved well at the earth surface and in strata except for enormously large scale volcanic eruption. In order to quantify quantitative characteristics of fine volcanic ash particle, we sampled volcanic ash directly falling from the eruption cloud from Showa crater, the most active vent of Sakurajima volcano, just before landing on ground. We newly adopted high precision digital microscope and particle grain size analyzer to develop hazard evaluation method of fine volcanic ash particle. Field survey was performed 5 sequential days in January, 2013 to take tamper-proof volcanic ash samples directly obtained from the eruption cloud of the Sakurajima volcano using disposable paper dishes and plastic pails. Samples were taken twice a day with time-stamp in 40 localities from 2.5 km to 43 km distant from the volcano. Japan Meteorological Agency reported 16 explosive eruptions of vulcanian style occurred during our survey and we took 140 samples of volcanic ash. Grain size distribution of volcanic ash was measured by particle grain size analyzer (Mophologi G3S) detecting each grain with parameters of particle diameter (0.3 micron - 1 mm), perimeter, length, area, circularity, convexity, solidity, and intensity. Component of volcanic ash was analyzed by CCD optical microscope (VHX-2000) which can take high resolution optical image with magnifying power of 100-2500. We discriminated each volcanic ash particle by color, texture of surface, and internal structure. Grain size distributions of volcanic ash from Sakurajima volcano have basically characteristics of unimodal and gaussian. Mode of distributions are 150 - 200 micron at 5 km and 70-80 micron at 20 km respectively from the Showa crater. Mode and deviation of the grain size distribution are function of distance from the source. Fine volcanic ash less than 1 micron in diameter is few and exists in every samples. Component of volcanic ash samples are dark-colored dense glass shard (ca. 50%), light-colored dense glass shard (10%), variously colored and vesiculated glass shard (10%), free crystal (20%), lithic fragment (10%), and altered fragment (less than 5%) which are mostly having similar ratio in every location suggesting single source process of the eruption. We also found fine volcanic ash samples less than 10 micron are frequently aggregated. The present study includes the result of "Research and Development of Margin Assessment Methodology of Decay Heat Removal Function against External Hazards" entrusted to Japan Atomic Energy Agency by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).

A preliminary investigation of projectile shape effects in hypervelocity impact of a double-sheet structure

NASA Technical Reports Server (NTRS)

Morrison, R. H.

1972-01-01

Impact tests of a sphere and several cylinders of various masses and fineness ratios, all of aluminum, fired into an aluminum double-sheet structure at velocities near 7 km/sec, show that a cylinder, impacting in the direction of its axis, is considerably more effective as a penetrator than a sphere. Impacts of three cylinders of equal mass, but different fineness ratios, produced holes through the structures' rear sheet, whereas impact of a sphere of the same mass did not. Moreover, it was found that to prevent rear-sheet penetration, the mass of the 1/2-fineness-ratio cylinder had to be reduced by a factor greater than three. Further tests wherein the cylinder diameter was held constant while the cylinder length was systematically reduced showed that a cylinder with a fineness ratio of 0.07 and a mass of only 1/7 that of the sphere was still capable of producing a hole in the rear sheet.

Clonal growth and fine-scale genetic structure in tanoak (Notholithocarpus densiflorus: Fagaceae)

Treesearch

Richard S. Dodd; Wasima Mayer; Alejandro Nettel; Zara Afzal-Rafii

2013-01-01

The combination of sprouting and reproduction by seed can have important consequences on fine-scale spatial distribution of genetic structure (SGS). SGS is an important consideration for species’ restoration because it determines the minimum distance among seed trees to maximize genetic diversity while not prejudicing locally adapted genotypes. Local environmental...

Cation distribution in NiZn-ferrite films via extended x-ray absorption fine structure

NASA Astrophysics Data System (ADS)

Harris, V. G.; Koon, N. C.; Williams, C. M.; Zhang, Q.; Abe, M.; Kirkland, J. P.

1996-04-01

We have applied extended x-ray absorption fine structure (EXAFS) spectroscopy to study the cation distribution in a series of spin-sprayed NiZn-ferrite films. A least-squares fitting of experimental EXAFS data with theoretical, multiple-scattering, EXAFS data allowed the quantitative determination of site distributions for all transition metal cations.

Precision microwave measurement of the 2(3)P(1)-2(3)P(0) interval in atomic helium: a determination of the fine-structure constant.

PubMed

George, M C; Lombardi, L D; Hessels, E A

2001-10-22

The 2(3)P(1)-to- 2(3)P(0) interval in atomic helium is measured using a thermal beam of metastable helium atoms excited to the 2(3)P state using a 1.08-microm diode laser. The 2(3)P(1)-to- 2(3)P(0) transition is driven by 29.6-GHz microwaves in a rectangular waveguide cavity. Our result of 29,616,950.9+/-0.9 kHz is the most precise measurement of helium 2(3)P fine structure. When compared to precise theory for this interval, this measurement leads to a determination of the fine-structure constant of 1/137.0359864(31).

Fine Structure of Reovirus Type 2

PubMed Central

Loh, Philip C.; Hohl, H. R.; Soergel, M.

1965-01-01

Loh, Philip C. (University of Hawaii, Honolulu), H. R. Hohl, and M. Soergel. Fine structure of reovirus type 2. J. Bacteriol. 89:1140–1144. 1965.—The fine structure reovirus type 2 was studied by electron microscopy with the negative-staining method. The virus has a mean diameter of 772 A and shows evidence of icosahedral shape and 5:3:2 symmetry. The particle is composed of a core, an inner layer, and a capsid composed of 92 elongated hollow capsomeres. These capsomeres have mean dimensions of 116 A × 110 A and a central hole 48 A in diameter. In size and architecture, reovirus type 2 is very similar to the other members (reoviruses types 1 and 3) of this group of animal viruses. Images PMID:14276109

Nine Years of Irrigation Cause Vegetation and Fine Root Shifts in a Water-Limited Pine Forest

PubMed Central

Herzog, Claude; Steffen, Jan; Graf Pannatier, Elisabeth; Hajdas, Irka; Brunner, Ivano

2014-01-01

Scots pines (Pinus sylvestris L.) in the inner-Alpine dry valleys of Switzerland have suffered from increased mortality during the past decades, which has been caused by longer and more frequent dry periods. In addition, a proceeding replacement of Scots pines by pubescent oaks (Quercus pubescens Willd.) has been observed. In 2003, an irrigation experiment was performed to track changes by reducing drought pressure on the natural pine forest. After nine years of irrigation, we observed major adaptations in the vegetation and shifts in Scots pine fine root abundance and structure. Irrigation permitted new plant species to assemble and promote canopy closure with a subsequent loss of herb and moss coverage. Fine root dry weight increased under irrigation and fine roots had a tendency to elongate. Structural composition of fine roots remained unaffected by irrigation, expressing preserved proportions of cellulose, lignin and phenolic substances. A shift to a more negative δ13C signal in the fine root C indicates an increased photosynthetic activity in irrigated pine trees. Using radiocarbon (14C) measurement, a reduced mean age of the fine roots in irrigated plots was revealed. The reason for this is either an increase in newly produced fine roots, supported by the increase in fine root biomass, or a reduced lifespan of fine roots which corresponds to an enhanced turnover rate. Overall, the responses belowground to irrigation are less conspicuous than the more rapid adaptations aboveground. Lagged and conservative adaptations of tree roots with decadal lifespans are challenging to detect, hence demanding for long-term surveys. Investigations concerning fine root turnover rate and degradation processes under a changing climate are crucial for a complete understanding of C cycling. PMID:24802642

Uniform 2 nm gold nanoparticles supported on iron oxides as active catalysts for CO oxidation reaction: structure-activity relationship

NASA Astrophysics Data System (ADS)

Guo, Yu; Gu, Dong; Jin, Zhao; Du, Pei-Pei; Si, Rui; Tao, Jing; Xu, Wen-Qian; Huang, Yu-Ying; Senanayake, Sanjaya; Song, Qi-Sheng; Jia, Chun-Jiang; Schüth, Ferdi

2015-03-01

Uniform Au nanoparticles (~2 nm) with narrow size-distribution (standard deviation: 0.5-0.6 nm) supported on both hydroxylated (Fe_OH) and dehydrated iron oxide (Fe_O) have been prepared by either deposition-precipitation (DP) or colloidal-deposition (CD) methods. Different structural and textural characterizations were applied to the dried, calcined and used gold-iron oxide samples. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) showed high homogeneity in the supported Au nanoparticles. The ex situ and in situ X-ray absorption fine structure (XAFS) characterization monitored the electronic and short-range local structure of active gold species. The synchrotron-based in situ X-ray diffraction (XRD), together with the corresponding temperature-programmed reduction by hydrogen (H2-TPR), indicated a structural evolution of the iron-oxide supports, correlating to their reducibility. An inverse order of catalytic activity between DP (Au/Fe_OH < Au/Fe_O) and CD (Au/Fe_OH > Au/Fe_O) was observed. Effective gold-support interaction results in a high activity for gold nanoparticles, locally generated by the sintering of dispersed Au atoms on the oxide support in the DP synthesis, while a hydroxylated surface favors the reactivity of externally introduced Au nanoparticles on Fe_OH support for the CD approach. This work reveals why differences in the synthetic protocol translate to differences in the catalytic performance of Au/FeOx catalysts with very similar structural characteristics in CO oxidation.

Uniform 2 nm gold nanoparticles supported on iron oxides as active catalysts for CO oxidation reaction: Structure-activity relationship

DOE PAGES

Guo, Yu; Senanayake, Sanjaya; Gu, Dong; ...

2015-01-12

Uniform Au nanoparticles (~2 nm) with narrow size-distribution (standard deviation: 0.5–0.6 nm) supported on both hydroxylated (Fe_OH) and dehydrated iron oxide (Fe_O) have been prepared by either deposition-precipitation (DP) or colloidal-deposition (CD) methods. Different structural and textural characterizations were applied to the dried, calcined and used gold-iron oxide samples. The transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) described the high homogeneity in the supported Au nanoparticles. The ex-situ and in-situ X-ray absorption fine structure (XAFS) characterization monitored the electronic and short-range local structure of active gold species. The synchrotron-based in-situ X-ray diffraction (XRD), together with the corresponding temperature-programmed reductionmore » by hydrogen (H₂-TPR), indicated a structural evolution of the iron-oxide supports, correlating to their reducibility. An inverse order of catalytic activity between DP (Au/Fe_OH < Au/Fe_O) and CD (Au/Fe_OH > Au/Fe_O) was observed. Effective gold-support interaction results in a high activity for gold nanoparticles, locally generated by the sintering of dispersed Au atoms on the oxide support in the DP synthesis, while a hydroxylated surface favors the reactivity of externally introduced Au nanoparticles on Fe_OH support for the CD approach. This work reveals why differences in the synthetic protocol translate to differences in the catalytic performance of Au/FeO x catalysts with very similar structural characteristics in CO oxidation.« less

Temporal changes in the structure of a plant-frugivore network are influenced by bird migration and fruit availability

PubMed Central

Andresen, Ellen; Díaz-Castelazo, Cecilia

2016-01-01

Background. Ecological communities are dynamic collections whose composition and structure change over time, making up complex interspecific interaction networks. Mutualistic plant–animal networks can be approached through complex network analysis; these networks are characterized by a nested structure consisting of a core of generalist species, which endows the network with stability and robustness against disturbance. Those mutualistic network structures can vary as a consequence of seasonal fluctuations and food availability, as well as the arrival of new species into the system that might disorder the mutualistic network structure (e.g., a decrease in nested pattern). However, there is no assessment on how the arrival of migratory species into seasonal tropical systems can modify such patterns. Emergent and fine structural temporal patterns are adressed here for the first time for plant-frugivorous bird networks in a highly seasonal tropical environment. Methods. In a plant-frugivorous bird community, we analyzed the temporal turnover of bird species comprising the network core and periphery of ten temporal interaction networks resulting from different bird migration periods. Additionally, we evaluated how fruit abundance and richness, as well as the arrival of migratory birds into the system, explained the temporal changes in network parameters such as network size, connectance, nestedness, specialization, interaction strength asymmetry and niche overlap. The analysis included data from 10 quantitative plant-frugivorous bird networks registered from November 2013 to November 2014. Results. We registered a total of 319 interactions between 42 plant species and 44 frugivorous bird species; only ten bird species were part of the network core. We witnessed a noteworthy turnover of the species comprising the network periphery during migration periods, as opposed to the network core, which did not show significant temporal changes in species composition. Our results revealed that migration and fruit richness explain the temporal variations in network size, connectance, nestedness and interaction strength asymmetry. On the other hand, fruit abundance only explained connectance and nestedness. Discussion. By means of a fine-resolution temporal analysis, we evidenced for the first time how temporal changes in the interaction network structure respond to the arrival of migratory species into the system and to fruit availability. Additionally, few migratory bird species are important links for structuring networks, while most of them were peripheral species. We showed the relevance of studying bird–plant interactions at fine temporal scales, considering changing scenarios of species composition with a quantitative network approach. PMID:27330852

Formation of fine sediment deposit from a flash flood river in the Mediterranean Sea

USGS Publications Warehouse

Grifoll, Manel; Gracia, Vicenç; Aretxabaleta, Alfredo L.; Guillén, Jorge; Espino, Manuel; Warner, John C.

2014-01-01

We identify the mechanisms controlling fine deposits on the inner-shelf in front of the Besòs River, in the northwestern Mediterranean Sea. This river is characterized by a flash flood regime discharging large amounts of water (more than 20 times the mean water discharge) and sediment in very short periods lasting from hours to few days. Numerical model output was compared with bottom sediment observations and used to characterize the multiple spatial and temporal scales involved in offshore sediment deposit formation. A high-resolution (50 m grid size) coupled hydrodynamic-wave-sediment transport model was applied to the initial stages of the sediment dispersal after a storm-related flood event. After the flood, sediment accumulation was predominantly confined to an area near the coastline as a result of preferential deposition during the final stage of the storm. Subsequent reworking occurred due to wave-induced bottom shear stress that resuspended fine materials, with seaward flow exporting them toward the midshelf. Wave characteristics, sediment availability, and shelf circulation determined the transport after the reworking and the final sediment deposition location. One year simulations of the regional area revealed a prevalent southwestward average flow with increased intensity downstream. The circulation pattern was consistent with the observed fine deposit depocenter being shifted southward from the river mouth. At the southern edge, bathymetry controlled the fine deposition by inducing near-bottom flow convergence enhancing bottom shear stress. According to the short-term and long-term analyses, a seasonal pattern in the fine deposit formation is expected.

Characterization and Cytotoxicity of PM<0.2, PM0.2–2.5 and PM2.5–10 around MSWI in Shanghai, China

PubMed Central

Cao, Lingling; Zeng, Jianrong; Liu, Ke; Bao, Liangman; Li, Yan

2015-01-01

Background: The potential impact of municipal solid waste incineration (MSWI), which is an anthropogenic source of aerosol emissions, is of great public health concern. This study investigated the characterization and cytotoxic effects of ambient ultrafine particles (PM<0.2), fine particles (PM0.2–2.5) and coarse particles (PM2.5–10) collected around a municipal solid waste incineration (MSWI) plant in the Pudong district of Shanghai. Methods: Mass concentrations of trace elements in particulate matter (PM) samples were determined using ICP-MS (Inductively Coupled Plasma Mass Spectrometry). The cytotoxicity of sampled atmospheric PM was evaluated by cell viability and reactive oxygen species (ROS) levels in A549 cells. Result: The mass percentage of PM0.2–2.5 accounted for 72.91% of the total mass of PM. Crustal metals (Mg, Al, and Ti) were abundant in the coarse particles, while the anthropogenic elements (V, Ni, Cu, Zn, Cd, and Pb) were dominant in the fine particles. The enrichment factors of Zn, Cd and Pb in the fine and ultrafine particles were extremely high (>100). The cytotoxicity of the size-resolved particles was in the order of coarse particles < fine particles < ultrafine particles. Conclusions: Fine particles dominated the MSWI ambient particles. Emissions from the MSWI could bring contamination of anthropogenic elements (Zn, Cd and Pb) into ambient environment. The PM around the MSWI plant displayed an additive toxic effect, and the ultrafine and fine particles possessed higher biological toxicity than the coarse particles. PMID:25985309

Iron solubility related to particle sulfur content in source emission and ambient fine particles.

PubMed

Oakes, M; Ingall, E D; Lai, B; Shafer, M M; Hays, M D; Liu, Z G; Russell, A G; Weber, R J

2012-06-19

The chemical factors influencing iron solubility (soluble iron/total iron) were investigated in source emission (e.g., biomass burning, coal fly ash, mineral dust, and mobile exhaust) and ambient (Atlanta, GA) fine particles (PM2.5). Chemical properties (speciation and mixing state) of iron-containing particles were characterized using X-ray absorption near edge structure (XANES) spectroscopy and micro-X-ray fluorescence measurements. Bulk iron solubility (soluble iron/total iron) of the samples was quantified by leaching experiments. Major differences were observed in iron solubility in source emission samples, ranging from low solubility (<1%, mineral dust and coal fly ash) up to 75% (mobile exhaust and biomass burning emissions). Differences in iron solubility did not correspond to silicon content or Fe(II) content. However, source emission and ambient samples with high iron solubility corresponded to the sulfur content observed in single particles. A similar correspondence between bulk iron solubility and bulk sulfate content in a series of Atlanta PM2.5 fine particle samples (N = 358) further supported this trend. In addition, results of linear combination fitting experiments show the presence of iron sulfates in several high iron solubility source emission and ambient PM2.5 samples. These results suggest that the sulfate content (related to the presence of iron sulfates and/or acid-processing mechanisms by H(2)SO(4)) of iron-containing particles is an important proxy for iron solubility.

Fine motor skills in adult Tourette patients are task-dependent.

PubMed

Neuner, Irene; Arrubla, Jorge; Ehlen, Corinna; Janouschek, Hildegard; Nordt, Carlos; Fimm, Bruno; Schneider, Frank; Shah, N Jon; Kawohl, Wolfram

2012-10-11

Tourette syndrome is a neuropsychiatric disorder characterized by motor and phonic tics. Deficient motor inhibition underlying tics is one of the main hypotheses in its pathophysiology. Therefore the question arises whether this supposed deficient motor inhibition affects also voluntary movements. Despite severe motor tics, different personalities who suffer from Tourette perform successfully as neurosurgeon, pilot or professional basketball player. For the investigation of fine motor skills we conducted a motor performance test battery in an adult Tourette sample and an age matched group of healthy controls. The Tourette patients showed a significant lower performance in the categories steadiness of both hands and aiming of the right hand in comparison to the healthy controls. A comparison of patients' subgroup without comorbidities or medication and healthy controls revealed a significant difference in the category steadiness of the right hand. Our results show that steadiness and visuomotor integration of fine motor skills are altered in our adult sample but not precision and speed of movements. This alteration pattern might be the clinical vignette of complex adaptations in the excitability of the motor system on the basis of altered cortical and subcortical components. The structurally and functionally altered neuronal components could encompass orbitofrontal, ventrolateral prefrontal and parietal cortices, the anterior cingulate, amygdala, primary motor and sensorimotor areas including altered corticospinal projections, the corpus callosum and the basal ganglia.

Multiple Time Series Node Synchronization Utilizing Ambient Reference

DTIC Science & Technology

2014-12-31

assessment, is the need for fine scale synchronization among communicating nodes and across multiple domains. The severe requirements that Special...processing targeted to performance assessment, is the need for fine scale synchronization among communicating nodes and across multiple domains. The...research community and it is well documented and characterized. The datasets considered from this project (listed below) were used to derive the

Photographic techniques for characterizing streambed particle sizes

USGS Publications Warehouse

Whitman, Matthew S.; Moran, Edward H.; Ourso, Robert T.

2003-01-01

We developed photographic techniques to characterize coarse (>2-mm) and fine (≤2-mm) streambed particle sizes in 12 streams in Anchorage, Alaska. Results were compared with current sampling techniques to assess which provided greater sampling efficiency and accuracy. The streams sampled were wadeable and contained gravel—cobble streambeds. Gradients ranged from about 5% at the upstream sites to about 0.25% at the downstream sites. Mean particle sizes and size-frequency distributions resulting from digitized photographs differed significantly from those resulting from Wolman pebble counts for five sites in the analysis. Wolman counts were biased toward selecting larger particles. Photographic analysis also yielded a greater number of measured particles (mean = 989) than did the Wolman counts (mean = 328). Stream embeddedness ratings assigned from field and photographic observations were significantly different at 5 of the 12 sites, although both types of ratings showed a positive relationship with digitized surface fines. Visual estimates of embeddedness and digitized surface fines may both be useful indicators of benthic conditions, but digitizing surface fines produces quantitative rather than qualitative data. Benefits of the photographic techniques include reduced field time, minimal streambed disturbance, convenience of postfield processing, easy sample archiving, and improved accuracy and replication potential.

Characterization of fine abrasive particles for optical fabrication

NASA Astrophysics Data System (ADS)

Funkenbusch, Paul D.; Zhou, Y. Y.; Takahashi, Toshio; Quesnel, David J.; Lambropoulos, John C.

1995-08-01

Material removal during fine grinding operations is accomplished primarily by the action of individual abrasive particles on the glass surface. The mechanical properties of the abrasive are therefore important. Unfortunately it is difficult to directly measure the mechanical response of abrasives once they reach the scale of approximately 10 microns. As a result mechanical properties of fine abrasives are sometimes characterized in terms of an empirical `friability', based on the response of the abrasive to crushing by a metal ball in a vial. In this paper we report on modeling/experiments designed to more precisely quantify the mechanical properties of fine abrasives and ultimately to relate them to the conditions experienced by bound particles during grinding. Experiments have been performed on various types and sizes of diamond abrasives. The response of the particles is a strong function of the loading conditions and can be tracked by changing the testing parameters. Diamond size is also found to play a critical role, with finer diamonds less susceptible to fracture. A micromechanical model from the literature is employed estimate the forces likely to be seen during testing. We are also developing dynamic models to better predict the forces experienced during `friability' testing as a function of the testing parameters.

Fine structure transitions in Fe XIV

NASA Astrophysics Data System (ADS)

Nahar, Sultana N.

2013-07-01

Results are reported for Fe XIV energy levels and transitions obtained from the ab initio relativistic Breit-Pauli R-matrix (BPRM) method. BPRM method developed under the Iron Project is capable of calculating very large number of fine structure energy levels and corresponding transitions. However, unlike in the atomic structure calculations, where levels are identified spectroscopically based on the leading percentage contributions of configurations, BPRM is incapable of such identification of the levels and hence the transitions. The main reason for it is that the percentage contributions can not be determined exactly from the large number of channels in the R-matrix space. The present report describes an identification method that uses considerations of quantum defects of channels, contributions of channel from outer regions, Hund's rule, and angular momenta algebra for addition and completeness of fine structure components. The present calculations are carried out using a close coupling wave function expansion that included 26 core excitations from configurations 2s22p63s2, 2s22p63s3p,2s22p63p2,2s22p63s3d, and 2s22p63p3d. A total of 1002 fine structure levels with n ⩽ 10, l⩽9, and 0.5 ⩽J⩽ 9.5 with even and odd parities and the corresponding 130,520 electric dipole allowed (E1) fine structure transitions, a most complete set for astrophysical modelings of spectral analysis and opacities, is presented. Large number of new energy levels are found and identified. The energies agree very well, mostly in less than 1% with the highest being 1.9%, with the 68 observed fine structure levels. While the high lying levels may have some uncertainty, an overall accuracy of energy levels should be within 10%. BPRM transitions have been benchmarked with the existing most accurate calculated transition probabilities with very good agreement for most cases. Based on the accuracy of the method and comparisons, most of the transitions can be rated with A (⩽10%) to C (⩽30%).

Size structure of marine soft-bottom macrobenthic communities across natural habitat gradients: implications for productivity and ecosystem function.

PubMed

Macdonald, Tara A; Burd, Brenda J; van Roodselaar, Albert

2012-01-01

Size distributions of biotic assemblages are important modifiers of productivity and function in marine sediments. We investigated the distribution of proportional organic biomass among logarithmic size classes (2(-6)J to 2(16)J) in the soft-bottom macrofaunal communities of the Strait of Georgia, Salish Sea on the west coast of Canada. The study examines how size structure is influenced by 3 fundamental habitat descriptors: depth, sediment percent fines, and organic flux (modified by quality). These habitat variables are uncorrelated in this hydrographically diverse area, thus we examine their effects in combination and separately. Cluster analyses and cumulative biomass size spectra reveal clear and significant responses to each separate habitat variable. When combined, habitat factors result in three distinct assemblages: (1) communities with a high proportion of biomass in small organisms, typical of shallow areas (<10 m) with coarse sediments (<10% fines) and low accumulation of organic material (<3.0 gC/m(2)/yr/δ(15)N); (2) communities with high proportion of biomass in the largest organisms found in the Strait, typical of deep, fine sediments with high modified organic flux (>3 g C/m(2)/yr/δ(15)N) from the Fraser River; and (3) communities with biomass dominated by moderately large organisms, but lacking the smallest and largest size classes, typical of deep, fine sediments experiencing low modified organic flux (<3.0 gC/m(2)/yr/δ(15)N). The remaining assemblages had intermediate habitat types and size structures. Sediment percent fines and flux appear to elicit threshold responses in size structure, whereas depth has the most linear influence on community size structure. The ecological implications of size structure in the Strait of Georgia relative to environmental conditions, secondary production and sediment bioturbation are discussed.

Size Structure of Marine Soft-Bottom Macrobenthic Communities across Natural Habitat Gradients: Implications for Productivity and Ecosystem Function

PubMed Central

Macdonald, Tara A.; Burd, Brenda J.; van Roodselaar, Albert

2012-01-01

Size distributions of biotic assemblages are important modifiers of productivity and function in marine sediments. We investigated the distribution of proportional organic biomass among logarithmic size classes (2−6J to 216J) in the soft-bottom macrofaunal communities of the Strait of Georgia, Salish Sea on the west coast of Canada. The study examines how size structure is influenced by 3 fundamental habitat descriptors: depth, sediment percent fines, and organic flux (modified by quality). These habitat variables are uncorrelated in this hydrographically diverse area, thus we examine their effects in combination and separately. Cluster analyses and cumulative biomass size spectra reveal clear and significant responses to each separate habitat variable. When combined, habitat factors result in three distinct assemblages: (1) communities with a high proportion of biomass in small organisms, typical of shallow areas (<10 m) with coarse sediments (<10% fines) and low accumulation of organic material (<3.0 gC/m2/yr/δ15N); (2) communities with high proportion of biomass in the largest organisms found in the Strait, typical of deep, fine sediments with high modified organic flux (>3 g C/m2/yr/δ15N) from the Fraser River; and (3) communities with biomass dominated by moderately large organisms, but lacking the smallest and largest size classes, typical of deep, fine sediments experiencing low modified organic flux (<3.0 gC/m2/yr/δ15N). The remaining assemblages had intermediate habitat types and size structures. Sediment percent fines and flux appear to elicit threshold responses in size structure, whereas depth has the most linear influence on community size structure. The ecological implications of size structure in the Strait of Georgia relative to environmental conditions, secondary production and sediment bioturbation are discussed. PMID:22911694

Nitriding of AISI 4140 steel by a low energy broad ion source

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

Ochoa, E. A.; Figueroa, C. A.; Alvarez, F.

2006-11-15

A comprehensive study of the thermochemical nitriding process of steel AISI 4140 by low energy ion implantation (Kaufmann cell) is reported. Different times of implantation were employed and the studied samples were characterized by x-ray diffraction, in situ photoemission electron spectroscopy, scanning electron microscopy, and hardness (nanoindentation) measurements. The linear relationship between nitrogen content and hardness was verified. The structure of the nitrided layer was characterized yielding that the compound layer is formed by coarse precipitates, around small grains, constituted principally by {epsilon}-Fe{sub 2-3}N and {gamma}-Fe{sub 4}N phases and the diffusion zone is formed by fine precipitates, around big grainsmore » of the original martensitic phase, constituted principally by {gamma}-Fe{sub 4}N phase. Finally, a diffusion model for multiphase systems was applied to determine effective diffusion coefficients of nitrogen in the different phases.« less

Spectroscopic characterization of N = 9 armchair graphene nanoribbons

DOE PAGES

Senkovskiy, B. V.; Haberer, D.; Usachov, D. Yu.; ...

2017-07-03

In this study, we investigate the N = 9 atoms wide armchair-type graphene nanoribbons (9-AGNRs) by performing a comprehensive spectroscopic and microscopic characterization of this novel material. In particular, we use X-ray photoelectron, near edge X-ray absorption fine structure, scanning tunneling, polarized Raman and angle-resolved photoemission (ARPES) spectroscopies. The ARPES measurements are aided by calculations of the photoemission matrix elements which yield the position in k space having the strongest photoemission cross section. Comparison with well-studied narrow N = 7 AGNRs shows that the effective electron mass in 9-AGNRs is reduced by two times and the valence band maximum ismore » shifted to lower binding energy by ~0.6 eV. In polarized Raman measurements of the aligned 9-AGNR, we reveal anisotropic signal depending upon the phonon symmetry. To conclude, our results indicate the 9-AGNRs are a novel 1D semiconductor with a high potential in nanoelectronic applications.« less

XFAS SPECTROSCOPY ANALYSIS OF SELECTED HAP ELEMENTS IN FINE PM DERIVED FROM COAL COMBUSTION: JOURNAL ARTICLE

EPA Science Inventory

NRMRL-RTP-P-646 Shoji, T., Huggins, F.E., Huffman, G.P., Linak*, W.P., and Miller*, C.A. XFAS Spectroscopy Analysis of Selected HAP Elements in Fine PM Derived from Coal Combustion. Energy and Fuels 16 (2): (2002). 11/30/2001 X-ray absorption fine structure (XAFS) spectroscop...

Enhanced dielectric properties of Fe-substituted TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ali, T.; Ahmed, Ateeq; Naseem siddique, M.; Tripathi, P.

2018-04-01

We report the structural and dielectric properties Ti1-xFexO2 (0.00 < x < 0.10) nanoparticles (NPs) synthesized by sol-gel method. The synthesized material has been characterized by soft X-ray absorption spectroscopy (SXAS) in order to investigate the fine structure and electronic valence state. SXAS analysis reveals that Fe-ions exist only in 3+ valance state in all the samples. The dielectric properties were studied by the use of LCR impedance spectroscopy. The dielectric constants, dielectric loss and A.C. conductivity have been determined as a function of frequency and composition of iron. At higher frequencies, the materials exhibited high AC Conductivity and low dielectric constant. The above theory could be explained by 'Maxwell Wagner Model' and may provide a new insight to fabricate nanomaterials having possible electrical application.

Selective separation of americium from europium using 2,9-bis(triazine)-1,10-phenanthrolines in ionic liquids: a new twist on an old story

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

Williams, Neil J.; Dehaudt, Jeremy; Bryantsev, Vyacheslav S.

Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, their limited solubility in traditional solvents remains a technological bottleneck. Here in this paper we report our recent work using a simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved in an ionic liquid (IL), demonstrating the efficacy of IL extraction systems for the selective separation of americium from europium, achieving separation factors in excess of 7500 and selectively removing up to 99% of the americium. Characterization of the coordination environment was performed using a combination ofmore » X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations.« less

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

NASA Astrophysics Data System (ADS)

Wu, Liang; Salehi, M.; Koirala, N.; Moon, J.; Oh, S.; Armitage, N. P.

2016-12-01

Topological insulators have been proposed to be best characterized as bulk magnetoelectric materials that show response functions quantized in terms of fundamental physical constants. Here, we lower the chemical potential of three-dimensional (3D) Bi2Se3 films to ~30 meV above the Dirac point and probe their low-energy electrodynamic response in the presence of magnetic fields with high-precision time-domain terahertz polarimetry. For fields higher than 5 tesla, we observed quantized Faraday and Kerr rotations, whereas the dc transport is still semiclassical. A nontrivial Berry’s phase offset to these values gives evidence for axion electrodynamics and the topological magnetoelectric effect. The time structure used in these measurements allows a direct measure of the fine-structure constant based on a topological invariant of a solid-state system.

Subcommunities and Their Mutual Relationships in a Transaction Network

NASA Astrophysics Data System (ADS)

Iino, T.; Iyetomi, H.

We investigate a Japanese transaction network consisting ofabout 800 thousand firms (nodes) and four million business relations (links) with focus on its modular structure. Communities detected by maximizing modularity often are dominated by firms with common features or behaviors in the network, such as characterized by regions or industry sectors. However, it is well known that the modularity optimization approach has a resolution limit problem, that is, it fails in identifying fine communities buried in large communities. To unfold such hidden structures, we apply the community detection to each of subnetworks formed by isolating those communities from the whole body. Subcommunities thus identified are composed of firms with finer regions, more specified sectors or business affiliations. Also we introduce a new idea of reduced modularity matrix to measure the strength of relations between (sub)communities.

Selective separation of americium from europium using 2,9-bis(triazine)-1,10-phenanthrolines in ionic liquids: a new twist on an old story

DOE PAGES

Williams, Neil J.; Dehaudt, Jeremy; Bryantsev, Vyacheslav S.; ...

2017-02-10

Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, their limited solubility in traditional solvents remains a technological bottleneck. Here in this paper we report our recent work using a simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved in an ionic liquid (IL), demonstrating the efficacy of IL extraction systems for the selective separation of americium from europium, achieving separation factors in excess of 7500 and selectively removing up to 99% of the americium. Characterization of the coordination environment was performed using a combination ofmore » X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations.« less

Development of eighteen microsatellite loci in walleye (Sander vitreus)

USGS Publications Warehouse

Coykendall, D. Katharine; Morrison, Cheryl L.; Stott, Wendylee; Springmann, Marcus J.

2014-01-01

A suite of tri- and tetra-nucleotide microsatellite loci were developed for walleye (Sander vitreus) from 454 pyrosequencing data. Eighteen of the 50 primer sets tested amplified consistently in 35 walleye from two lakes on Isle Royale, Lake Superior: Chickenbone Lake and Whittlesey Lake. The loci displayed moderate levels of allelic diversity (average 5.5 alleles/locus) and heterozygosity (average 35.8 %). Levels of genetic diversity were sufficient to produce unique multi-locus genotypes and detect phylogeographic structuring as individuals assigned back to their population of origin. Cross-species amplification within S. canadensis(sauger) was successful for 15 loci, and 11 loci were diagnostic to species. The loci characterized here will be useful for detecting fine-scale spatial structuring, resolving the taxonomic status of Sander species and sub-species, and detecting walleye/sauger hybrids.

Chemical Fucosylation of a Polysaccharide: A Semisynthetic Access to Fucosylated Chondroitin Sulfate.

PubMed

Laezza, Antonio; Iadonisi, Alfonso; Castro, Cristina De; De Rosa, Mario; Schiraldi, Chiara; Parrilli, Michelangelo; Bedini, Emiliano

2015-07-13

Chemical O-glycosylation of polysaccharides is an almost unexplored reaction. This is mainly due to the difficulties in derivatizing such complex biomacromolecules in a quantitative manner and with a fine control of the obtained structural parameters. In this work, chondroitin raw material from a microbial source was chemo- and regioselectively protected to give two polysaccharide intermediates, that acted in turn as glycosyl acceptors in fucosylation reactions. Further manipulations on the fucosylated polysaccharides, including multiple de-O-benzylation and sulfation, furnished for the first time nonanimal sourced fucosylated chondroitin sulfates (fCSs)-polysaccharides obtained so far exclusively from sea cucumbers (Echinoidea, Holothuroidea) and showing several very interesting biological activities. A semisynthetic fCS was characterized from a structural point of view by means of 2D-NMR techniques, and preliminarily assayed in an anticoagulant test.

Regional haze case studies in the southwestern U.S—I. Aerosol chemical composition

NASA Astrophysics Data System (ADS)

Macias, Edward S.; Zwicker, Judith O.; Ouimette, James R.; Hering, Susanne V.; Friedlander, Sheldon K.; Cahill, Thomas A.; Kuhlmey, Gregory A.; Richards, L. Willard

Aerosol chemical composition as a function of particle size was determined in the southwestern U.S.A. during four weeks of sampling in June, July and December, 1979 as a part of project VISITA. Samples were collected at two ground stations about 80 km apart near Page (AZ) and in two aircraft flying throughout the region. Several different size separating aerosol samplers and chemical analysis procedures were intercompared and were used in determining the size distribution and elemental composition of the aerosol. Sulfur was shown to be in the form of water soluable sulfate, highly correlated with ammonium ion, and with an average [NH +4]/[SO 2-4] molar ratio of 1.65. During the summer sampling period, three distinct regimes were observed, each with a different aerosol composition. The first, 24 h sampling ending 30 June, was characterized by a higher than average value of light scattering due to particles (b sp) of 24 × 10 -6m-1 and a fine particulate mass ( Mf) of 8.5 μg m -1. The fine particle aerosol was dominated by sulfate and carbon. Aircraft measurements showed the aerosol was homogeneous throughout the region at that time. The second regime, 5 July, had the highest average bsp of 51 × 10 -6m -1 during the sampling period with Mf of 3.2 μgm -3. The fine particle aerosol had nearly equal concentrations of carbon and ammonium sulfate. For all three regimes, enrichment factor analysis indicated fine and coarse particle Cu, Zn, Cl, Br, and Pb and fine particle K were enriched above crustal concentrations relative to Fe, indicating that these elements were present in the aerosol from sources other than wind blown dust. Particle extinction budgets calculated for the three regimes indicated that fine particles contributed most significantly, with carbon and (NH 4) 2SO 4 making the largest contributions. Fine particle crustal elements including Si did not contribute significantly to the extinction budget during this study. The December sampling was characterized by very light fine particle loading with two regimes identified. One regime had higher fine mass and sulfate concentrations while the other had low values for all species measured.

Studies on the wintertime current structure and T-S fine-structure in the Taiwan Strait

NASA Astrophysics Data System (ADS)

Hu, Jianyu; Fu, Zilang; Wu, Lianxing

1990-12-01

A cruise through the western sea area of the Taiwan Strait was carried out by the R/V Dong Fang Hong in December, 1987. Eight anchored and 10 not anchored stations were set up. Over 25 time-series current observations were made at each station and CTD (Conductivity-temperature-depth) measurements were made at 5 anchored and 10 not anchored stations. Based on the measured data. fine-structures and step-like vertical structures of temperature and salinity were analysed and a tentative wintertime current structure in the Taiwan Strait was described.

Mechanical properties of a Gum-type Ti-Nb-Zr-Fe-O alloy

NASA Astrophysics Data System (ADS)

Nocivin, Anna; Cinca, Ion; Raducanu, Doina; Cojocaru, Vasile Danut; Popovici, Ion Alexandru

2017-08-01

A new Gum-type alloy (Ti-Nb-Zr-Fe-O) in which Fe is used instead of Ta was subjected to a particular thermomechanical processing scheme to assess whether its mechanical characteristics (fine β-grains with high strength and low modulus) render it suitable as a biomedical implant material. After a homogenization treatment followed by cold-rolling with 50% reduction, the specimens were subjected to one of three different recrystallization treatments at 1073, 1173, and 1273 K. The structural and mechanical properties of all of the treated specimens were analyzed. The mechanical characterization included tensile tests, microhardness determinations, and fractography by scanning electron microscopy. The possible deformation mechanisms were discussed using the \\overline {Bo} - \\overline {Md} diagram. By correlating all of the experimental results, we concluded that the most promising processing variant corresponds to recrystallization at 1073 K, which can provide suitable mechanical characteristics for this type of alloys: high yield and ultimate tensile strengths (1038 and 1083 MPa, respectively), a low modulus of elasticity (62 GPa), and fine crystalline grain size (approximately 50 μm).

Effects of a suppressor tone on distortion product otoacoustic emissions fine structure: why a universal suppressor level is not a practical solution to obtaining single-generator DP-grams.

PubMed

Dhar, Sumitrajit; Shaffer, Lauren A

2004-12-01

The use of a suppressor tone has been proposed as the method of choice in obtaining single-generator distortion product (DP) grams, the speculation being that such DP grams will be more predictive of hearing thresholds. Current distortion product otoacoustic emissions (DPOAE) theory points to the ear canal DPOAE signal being a complex interaction between multiple components. The effectiveness of a suppressor tone is predicted to be dependent entirely on the relative levels of these components. We examine the validity of using a suppressor tone through a detailed examination of the effects of a suppressor on DPOAE fine structure in individual ears. DPOAE fine structure, recorded in 10 normal-hearing individuals with a suppressor tone at 45, 55, and 65 dB SPL, was compared with recordings without a suppressor. Behavioral hearing thresholds were also measured in the same subjects, using 2-dB steps. The effect of the suppressor tone on DPOAE fine structure varied between ears and was dependent on frequency within ears. Correlation between hearing thresholds and DPOAE level measured without a suppressor was similar to previous reports. The effects of the suppressor are explained in the theoretical framework of a model involving multiple DPOAE components. Our results suggest that a suppressor tone can have highly variable effects on fine structure across individuals or even across frequency within one ear, thereby making the use of a suppressor less viable as a clinical tool for obtaining single-generator DP grams.

Imaging the Fine-Scale Structure of the San Andreas Fault in the Northern Gabilan Range with Explosion and Earthquake Sources

NASA Astrophysics Data System (ADS)

Xin, H.; Thurber, C. H.; Zhang, H.; Wang, F.

2014-12-01

A number of geophysical studies have been carried out along the San Andreas Fault (SAF) in the Northern Gabilan Range (NGR) with the purpose of characterizing in detail the fault zone structure. Previous seismic research has revealed the complex structure of the crustal volume in the NGR region in two-dimensions (Thurber et al., 1996, 1997), and there has been some work on the three-dimensional (3D) structure at a coarser scale (Lin and Roecker, 1997). In our study we use earthquake body-wave arrival times and differential times (P and S) and explosion arrival times (only P) to image the 3D P- and S-wave velocity structure of the upper crust along the SAF in the NGR using double-difference (DD) tomography. The earthquake and explosion data types have complementary strengths - the earthquake data have good resolution at depth and resolve both Vp and Vs structure, although only where there are sufficient seismic rays between hypocenter and stations, whereas the explosions contribute very good near-surface resolution but for P waves only. The original dataset analyzed by Thurber et al. (1996, 1997) included data from 77 local earthquakes and 8 explosions. We enlarge the dataset with 114 more earthquakes that occurred in the study area, obtain improved S-wave picks using an automated picker, and include absolute and cross-correlation differential times. The inversion code we use is the algorithm tomoDD (Zhang and Thurber, 2003). We assess how the P and S velocity models and earthquake locations vary as we alter the inversion parameters and the inversion grid. The new inversion results show clearly the fine-scale structure of the SAF at depth in 3D, sharpening the image of the velocity contrast from the southwest side to the northeast side.

Gravity Wave Interactions with Fine Structures in the Mesosphere and Lower Thermosphere

NASA Astrophysics Data System (ADS)

Mixa, Tyler; Fritts, David; Bossert, Katrina; Laughman, Brian; Wang, Ling; Lund, Thomas; Kantha, Lakshmi

2017-04-01

An anelastic numerical model is used to probe the influences of fine layering structures on gravity wave propagation in the Mesosphere and Lower Thermosphere (MLT). Recent lidar observations confirm the presence of persistent layered structures in the MLT that have sharp stratification and vertical scales below 1km. Gravity waves propagating through finely layered environments can excite and modulate the evolution of small scale instabilities that redefine the layering structure in these regions. Such layers in turn filter the outgoing wave spectra, promote ducting or reflection, hasten the onset of self-acceleration dynamics, and encourage wave/mean-flow interactions via energy and momentum transport. Using high resolution simulations of a localized gravity wave packet in a deep atmosphere, we identify the relative impacts of various wave and mean flow parameters to improve our understanding of these dynamics and complement recent state-of-the-art observations.

Strained spiral vortex model for turbulent fine structure

NASA Technical Reports Server (NTRS)

Lundgren, T. S.

1982-01-01

A model for the intermittent fine structure of high Reynolds number turbulence is proposed. The model consists of slender axially strained spiral vortex solutions of the Navier-Stokes equation. The tightening of the spiral turns by the differential rotation of the induced swirling velocity produces a cascade of velocity fluctuations to smaller scale. The Kolmogorov energy spectrum is a result of this model.

Photoionization modeling of the LWS fine-structure lines in IR bright galaxies

NASA Technical Reports Server (NTRS)

Satyapal, S.; Luhman, M. L.; Fischer, J.; Greenhouse, M. A.; Wolfire, M. G.

1997-01-01

The long wavelength spectrometer (LWS) fine structure line spectra from infrared luminous galaxies were modeled using stellar evolutionary synthesis models combined with photoionization and photodissociation region models. The calculations were carried out by using the computational code CLOUDY. Starburst and active galactic nuclei models are presented. The effects of dust in the ionized region are examined.

Study of the Role of Vortex Annihilation in the Mechanism of Neutron and X-Ray Production in the Plasma Focus.

DTIC Science & Technology

This paper shows that an understanding of the nature of the x-ray and neutron producing processes in the plasma focus requires a study of the ’fine...structure’ of the plasma focus and that this fine structure study requires diagnostic techniques with spacial resolution down to 50 micrometers and

Titanium dioxide fine structures by RF magnetron sputter method deposited on an electron-beam resist mask

NASA Astrophysics Data System (ADS)

Hashiba, Hideomi; Miyazaki, Yuta; Matsushita, Sachiko

2013-09-01

Titanium dioxide (TiO2) has been draw attention for wide range of applications from photonic crystals for visible light range by its catalytic characteristics to tera-hertz range by its high refractive index. We present an experimental study of fabrication of fine structures of TiO2 with a ZEP electron beam resist mask followed by Ti sputter deposition techniques. A TiO2 thin layer of 150 nm thick was grown on an FTO glass substrate with a fine patterned ZEP resist mask by a conventional RF magnetron sputter method with Ti target. The deposition was carried out with argon-oxygen gases at a pressure of 5.0 x 10 -1 Pa in a chamber. During the deposition, ratio of Ar-O2 gas was kept to the ratio of 2:1 and the deposition ratio was around 0.5 Å/s to ensure enough oxygen to form TiO2 and low temperature to avoid deformation of fine pattern of the ZPU resist mask. Deposited TiO2 layers are white-transparent, amorphous, and those roughnesses are around 7 nm. Fabricated TiO2 PCs have wider TiO2 slabs of 112 nm width leaving periodic 410 x 410 nm2 air gaps. We also studied transformation of TiO2 layers and TiO2 fine structures by baking at 500 °C. XRD measurement for TiO2 shows that the amorphous TiO2 transforms to rutile and anatase forms by the baking while keeping the same profile of the fine structures. Our fabrication method can be one of a promising technique to optic devices on researches and industrial area.

Effective Collision Strengths for Fine-structure Transitions in Si VII

NASA Astrophysics Data System (ADS)

Sossah, A. M.; Tayal, S. S.

2014-05-01

The effective collision strengths for electron-impact excitation of fine-structure transitions in Si VII are calculated as a function of electron temperature in the range 5000-2,000,000 K. The B-spline Breit-Pauli R-matrix method has been used to calculate collision strengths by electron impact. The target wave functions have been obtained using the multi-configuration Hartree-Fock method with term-dependent non-orthogonal orbitals. The 92 fine-structure levels belonging to the 46 LS states of 2s 22p 4, 2s2p 5, 2p 6, 2s 22p 33s, 2s 22p 33p, 2s 22p 33d, and 2s2p 43s configurations are included in our calculations of oscillator strengths and collision strengths. There are 4186 possible fine-structure allowed and forbidden transitions among the 92 levels. The present excitation energies, oscillator strengths, and collision strengths have been compared with previous theoretical results and available experimental data. Generally, a good agreement is found with the 6 LS-state close-coupling approximation results of Butler & Zeippen and the 44 LS-state distorted wave calculation of Bhatia & Landi.

Rotational and fine structure of open-shell molecules in nearly degenerate electronic states

NASA Astrophysics Data System (ADS)

Liu, Jinjun

2018-03-01

An effective Hamiltonian without symmetry restriction has been developed to model the rotational and fine structure of two nearly degenerate electronic states of an open-shell molecule. In addition to the rotational Hamiltonian for an asymmetric top, this spectroscopic model includes the energy separation between the two states due to difference potential and zero-point energy difference, as well as the spin-orbit (SO), Coriolis, and electron spin-molecular rotation (SR) interactions. Hamiltonian matrices are computed using orbitally and fully symmetrized case (a) and case (b) basis sets. Intensity formulae and selection rules for rotational transitions between a pair of nearly degenerate states and a nondegenerate state have also been derived using all four basis sets. It is demonstrated using real examples of free radicals that the fine structure of a single electronic state can be simulated with either a SR tensor or a combination of SO and Coriolis constants. The related molecular constants can be determined precisely only when all interacting levels are simulated simultaneously. The present study suggests that analysis of rotational and fine structure can provide quantitative insights into vibronic interactions and related effects.

Lyapunov exponents for one-dimensional aperiodic photonic bandgap structures

NASA Astrophysics Data System (ADS)

Kissel, Glen J.

2011-10-01

Existing in the "gray area" between perfectly periodic and purely randomized photonic bandgap structures are the socalled aperoidic structures whose layers are chosen according to some deterministic rule. We consider here a onedimensional photonic bandgap structure, a quarter-wave stack, with the layer thickness of one of the bilayers subject to being either thin or thick according to five deterministic sequence rules and binary random selection. To produce these aperiodic structures we examine the following sequences: Fibonacci, Thue-Morse, Period doubling, Rudin-Shapiro, as well as the triadic Cantor sequence. We model these structures numerically with a long chain (approximately 5,000,000) of transfer matrices, and then use the reliable algorithm of Wolf to calculate the (upper) Lyapunov exponent for the long product of matrices. The Lyapunov exponent is the statistically well-behaved variable used to characterize the Anderson localization effect (exponential confinement) when the layers are randomized, so its calculation allows us to more precisely compare the purely randomized structure with its aperiodic counterparts. It is found that the aperiodic photonic systems show much fine structure in their Lyapunov exponents as a function of frequency, and, in a number of cases, the exponents are quite obviously fractal.

Distinct local structure of superconducting Ca10M4As8(Fe2As2)5 (M =Pt ,Ir)

NASA Astrophysics Data System (ADS)

Paris, E.; Wakita, T.; Proux, O.; Yokoya, T.; Kudo, K.; Mitsuoka, D.; Kimura, T.; Fujimura, K.; Nishimoto, N.; Ioka, S.; Nohara, M.; Mizokawa, T.; Saini, N. L.

2017-12-01

We have studied the local structure of superconducting Ca10Pt4As8(Fe2As2)5 (Pt10418) and Ca10Ir4As8(Fe2As2)5 (Ir10418) iron arsenides, showing different transition temperatures (Tc=38 and 16 K, respectively), by polarized Fe K -edge extended x-ray absorption fine-structure measurements. Despite the similar average crystal structures, the local structures of the FeAs4 tetrahedra in the two compounds are found to be very different. The FeAs4 in Pt10418 is close to a regular tetrahedron, while it deviates largely in Ir10418. The Fe-Fe correlations in the two compounds are characterized by similar bond-length characteristics; however, the static disorder in Pt10418 is significantly lower than that in Ir10418. The results suggest that the optimized local structure and reduced disorder are the reasons for higher Tc and well-defined electronic states in Pt10418 unlike Ir10418 showing the coexistence of glassy and normal electrons at the Fermi surface, and hence provide direct evidence of the local-structure-driven optimization of the electronic structure and superconductivity in iron arsenides.

Metal Ion Dependence of the Matrix Metalloproteinase-1 Mechanism.

PubMed

Yang, Hao; Makaroff, Katherine; Paz, Nicholas; Aitha, Mahesh; Crowder, Michael W; Tierney, David L

2015-06-16

Matrix metalloproteinase-1 (MMP-1) plays crucial roles in disease-related physiologies and pathological processes in the human body. We report here solution studies of MMP-1, including characterization of a series of mutants designed to bind metal in either the catalytic site or the structural site (but not both). Circular dichroism and fluorescence spectroscopy of the mutants demonstrate the importance of the structural Zn(II) in maintaining both secondary and tertiary structure, while UV-visible, nuclear magnetic resonance, electron paramagnetic resonance, and extended X-ray absorption fine structure show its presence influences the catalytic metal ion's coordination number. The mutants allow us to demonstrate convincingly the preparation of a mixed-metal analogue, Co(C)Zn(S)-MMP-1, with Zn(II) in the structural site and Co(II) in the catalytic site. Stopped-flow fluorescence of the native form, Zn(C)Zn(S)-MMP-1, and the mixed-metal Co(C)Zn(S)-MMP-1 analogue shows that the internal fluorescence of a nearby Trp residue is modulated with catalysis and can be used to monitor reactivity under a number of conditions, opening the door to substrate profiling.

Mealybug species from Chilean agricultural landscapes and main factors influencing the genetic structure of Pseudococcus viburni

PubMed Central

Correa, Margarita C. G.; Lombaert, Eric; Malausa, Thibaut; Crochard, Didier; Alvear, Andrés; Zaviezo, Tania; Palero, Ferran

2015-01-01

The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader. PMID:26559636

Nanoscale structural and electronic characterization of α-RuCl3 layered compound

NASA Astrophysics Data System (ADS)

Ziatdinov, Maxim; Maksov, Artem; Banerjee, Arnab; Zhou, Wu; Berlijn, Tom; Yan, Jiaqiang; Nagler, Stephen; Mandrus, David; Baddorf, Arthur; Kalinin, Sergei

The exceptional interplay of spin-orbit effects, Coulomb interaction, and electron-lattice coupling is expected to produce an elaborate phase space of α-RuCl3 layered compound, which to date remains largely unexplored. Here we employ a combination of scanning transmission electron microscopy (STEM) and scanning tunneling microscopy (STM) for detailed evaluation of the system's microscopic structural and electronic orders with a sub-nanometer precision. The STM and STEM measurements are further supported by neutron scattering, X-Ray diffraction, density functional theory (DFT), and multivariate statistical analysis. Our results show a trigonal distortion of Cl octahedral ligand cage along the C3 symmetry axes in each RuCl3 layer. The lattice distortion is limited mainly to the Cl subsystem leaving the Ru honeycomb lattice nearly intact. The STM topographic and spectroscopic characterization reveals an intra unit cell electronic symmetry breaking in a spin-orbit coupled Mott insulating phase on the Cl-terminated surface of α-RuCl3. The associated long-range charge order (CO) pattern is linked to a surface component of Cl cage distortion. We finally discuss a fine structure of CO and its potential relation to variations of average unit cell geometries found in multivariate analysis of STEM data. The research was sponsored by the U.S. Department of Energy.

Structural Coloration of a Colloidal Amorphous Array is Intensified by Carbon Nanolayers.

PubMed

Takeoka, Yukikazu; Iwata, Masanori; Seki, Takahiro; Nueangnoraj, Khanin; Nishihara, Hirotomo; Yoshioka, Shinya

2018-04-10

In this study, we introduce the possibility of applying a colloidal amorphous array composed of fine silica particles as a structural-color material to invisible information technology. The appearance of a thick filmlike colloidal amorphous array formed from fine silica particles is considerably influenced by incoherent light scattering across the entire visible region. Therefore, regardless of the diameter of the fine silica particles, the thick colloidal amorphous array exhibits a white color to the naked eye. When carbon is uniformly deposited in the colloidal amorphous array by a pressure-pulsed chemical vapor deposition method, incoherent light scattering in the colloidal amorphous array is suppressed. As a result, coherent light scattering due to the short-range order in the colloidal amorphous array becomes conspicuous and the array exhibits a vivid structural color. As structures, such as letters and pictures, can be drawn using this technology, the colloidal amorphous array as a structural-colored material may also be applicable for invisible information technology.

Human brain detects short-time nonlinear predictability in the temporal fine structure of deterministic chaotic sounds

NASA Astrophysics Data System (ADS)

Itoh, Kosuke; Nakada, Tsutomu

2013-04-01

Deterministic nonlinear dynamical processes are ubiquitous in nature. Chaotic sounds generated by such processes may appear irregular and random in waveform, but these sounds are mathematically distinguished from random stochastic sounds in that they contain deterministic short-time predictability in their temporal fine structures. We show that the human brain distinguishes deterministic chaotic sounds from spectrally matched stochastic sounds in neural processing and perception. Deterministic chaotic sounds, even without being attended to, elicited greater cerebral cortical responses than the surrogate control sounds after about 150 ms in latency after sound onset. Listeners also clearly discriminated these sounds in perception. The results support the hypothesis that the human auditory system is sensitive to the subtle short-time predictability embedded in the temporal fine structure of sounds.

The fine structure of human germ layers in vivo: clues to the early differentiation of embryonic stem cells in vitro.

PubMed

Sathananthan, Henry; Selvaraj, Kamala; Clark, Joan

2011-08-01

The fine structure of the three germ layers in human ectopic embryos (stage 7) have been documented by digital light and electron microscopy. The formation of ectoderm, endoderm and mesoderm and notochordal cells, and also the extraembryonic membranes, amnion and yolk sac, are imaged. The germ layers give rise to all the cells and tissues of the human body. Possible clues to the early differentiation of embryonic stem cells (ESC) in vitro were obtained, since these events are more or less mimicked in cultures of ESC derived from the inner cell mass of human blastocysts. The findings are discussed with reference to previous studies on the fine structure of ESC using the same technique. Copyright © 2011. Published by Elsevier Ltd.

21-cm radiation: a new probe of variation in the fine-structure constant.

PubMed

Khatri, Rishi; Wandelt, Benjamin D

2007-03-16

We investigate the effect of variation in the value of the fine-structure constant (alpha) at high redshifts (recombination > z > 30) on the absorption of the cosmic microwave background (CMB) at 21 cm hyperfine transition of the neutral atomic hydrogen. We find that the 21 cm signal is very sensitive to the variations in alpha and it is so far the only probe of the fine-structure constant in this redshift range. A change in the value of alpha by 1% changes the mean brightness temperature decrement of the CMB due to 21 cm absorption by >5% over the redshift range z < 50. There is an effect of similar magnitude on the amplitude of the fluctuations in the brightness temperature. The redshift of maximum absorption also changes by approximately 5%.

Measuring the fine structure constant with Bragg diffraction and Bloch oscillations

NASA Astrophysics Data System (ADS)

Parker, Richard; Yu, Chenghui; Zhong, Weicheng; Estey, Brian; Müller, Holger

2017-04-01

We have demonstrated a new scheme for atom interferometry based on large-momentum-transfer Bragg beam splitters and Bloch oscillations. In this new scheme, we have achieved a resolution of δÎ+/-/Î+/-=0.25ppb in the fine structure constant measurement, which gives over 10 million radians of phase difference between freely evolving matter waves. We have suppressed many systematic effects known in most atom interferometers with Raman beam splitters such as light shift, Zeeman effect shift as well as vibration. We have also simulated multi-atom Bragg diffraction to understand sub-ppb systematic effects, and implemented spatial filtering to further suppress systematic effects. We present our recent progress toward a measurement of the fine structure constant, which will provide a stringent test of the standard model of particle physics.

Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

USGS Publications Warehouse

Wright, S.A.; Kaplinski, M.

2011-01-01

In canyon rivers, debris fan constrictions create rapids and downstream pools characterized by secondary flow structures that are closely linked to channel morphology. In this paper we describe detailed measurements of the three-dimensional flow structure and sandbar dynamics of two pools along the Colorado River in the Grand Canyon during a controlled flood release from Glen Canyon Dam. Results indicate that the pools are characterized by large lateral recirculation zones (eddies) resulting from flow separation downstream from the channel constrictions, as well as helical flow structures in the main channel and eddy. The lateral recirculation zones are low-velocity areas conducive to fine sediment deposition, particularly in the vicinity of the separation and reattachment points and are thus the dominant flow structures controlling sandbar dynamics. The helical flow structures also affect morphology but appear secondary in importance to the lateral eddies. During the controlled flood, sandbars in the separation and reattachment zones at both sites tended to build gradually during the rising limb and peak flow. Deposition in shallow water on the sandbars was accompanied by erosion in deeper water along the sandbar slope at the interface with the main channel. Erosion occurred via rapid mass failures as well as by gradual boundary shear stress driven processes. The flow structures and morphologic links at our study sites are similar to those identified in other river environments, in particular sharply curved meanders and channel confluences where the coexistence of lateral recirculation and helical flows has been documented. Copyright 2011 by the American Geophysical Union.

Improving disease resistance of butternut (Juglans cinerea), a threatened fine hardwood: a case for single-tree selection through genetic improvement and deployment.

PubMed

Michler, Charles H; Pijut, Paula M; Jacobs, Douglass F; Meilan, Richard; Woeste, Keith E; Ostry, Michael E

2006-01-01

Approaches for the development of disease-resistant butternut (Juglans cinerea L.) are reviewed. Butternut is a threatened fine hardwood throughout its natural range in eastern North America because of the invasion of the exotic fungus, Sirococcus clavigignenti-juglandacearum Nair, Kostichka and Kuntz, which causes butternut canker. Early efforts were made to identify and collect putatively resistant germ plasm, identify vectors and to characterize the disease. More recently, molecular techniques have been employed to genetically characterize both the pathogen and the resistant germ plasm. Much of the host resistance may originate from hybridization with a close Asian relative, Japanese walnut (Juglans ailanthifolia Carr.), and from a few natural phenotypic variants. Further genetic characterization is needed before classical breeding or genetic modification can be used to produce canker-resistant trees.

VERSATILE AEROSOL CONCENTRATION ENRICHMENT SYSTEM (VACES) FOR SIMULTANEOUS IN VIVO AND IN VITRO EVALUATION OF TOXIC EFFECTS OF ULTRAFINE, FINE AND COARSE AMBIENT PARTICLES. PART I: DEVELOPMENT AND LABORATORY CHARACTERIZATION. (R827352C001)

EPA Science Inventory

This study presents the development and bench-testing of a versatile aerosol concentration enrichment system (VACES) capable of simultaneously concentrating ambient particles of the coarse, fine and ultrafine size fractions for conducting in vivo and in vitro studies. The VACE...

Relationship of Species and Site Index to Habitat in the White Mountains of New Hampshire

Treesearch

W. B. Leak

1978-01-01

Eleven forest habitats, representing distinct differences in soil materials or substrate, were defined for areas of granitic drift in the White Mountains of New Hampshire. Beech/sugar maple/yellow birch characterize successional stands on the fine tills and the enriched or cove sites (where white ash also is common). Washed fine till and coarse till are dominated...

The Kara and Ust-Kara impact structures (USSR) and their relevance to the K/T boundary event

NASA Technical Reports Server (NTRS)

Koeberl, Christian; Nazarov, M. A.; Harrison, T. M.; Sharpton, V. L.; Murali, A. V.; Burke, K.

1988-01-01

The Kara and Ust-Kara craters are twin impact structures situated at about 69 deg 10 min N; 65 deg 00 min E at the Kara Sea. For Kara a diameter of about 55 km would be a very conservative estimate, and field observations indicate a maximum current diameter of about 60 km. The diameter of Ust-Kara has to be larger than 16 km. A better estimate might be 25 km but in all likelihood it is even larger. Suevites and impactites from the Kara area have been known since the beginning of the century, but had been misidentified as glacial deposits. Only about 15 years ago the impact origin of the two structures was demonstrated, following the recognition of shock metamorphism in the area. The composition of the target rocks is mirrored by the composition of the clasts within the suevites. In the southern part of Kara, Permian shales and limestones are sometimes accompanied by diabasic dykes, similar to in the central uplift. Due to the high degree of shock metamorphism the shocked magmatic rocks are not easily identified, although most of them seem to be of diabasic or dioritic composition. The impact melts (tagamites) are grey to dark grey fine grained crystallized rocks showing very fine mineral components and are the product of shock-melting with later recrystallization. The impact glasses show a layered structure, inclusions, and vesicles, and have colors ranging from translucent white over brown and grey to black. A complete geochemical characterization of the Kara and Ust-Kara impact craters was attempted by analyzing more than 40 samples of target rocks, shocked rocks, suevites, impact melts, and impact glasses for major and trace elements.

Sorption behavior of the Pt(II) complex anion on manganese dioxide (δ-MnO2): a model reaction to elucidate the mechanism by which Pt is concentrated into a marine ferromanganese crust

NASA Astrophysics Data System (ADS)

Maeno, Mamiko Yamashita; Ohashi, Hironori; Yonezu, Kotaro; Miyazaki, Akane; Okaue, Yoshihiro; Watanabe, Koichiro; Ishida, Tamao; Tokunaga, Makoto; Yokoyama, Takushi

2016-02-01

It is difficult to directly investigate the chemical state of Pt in marine ferromanganese crusts (a mixture of hydrous iron(III) oxide and manganese dioxide (δ-MnO2)) because it is present at extremely low concentration levels. This paper attempts to elucidate the mechanism by which Pt is concentrated into marine ferromanganese crust from the Earth's continental crust through ocean water. In this investigation, the sorption behavior of the Pt(II) complex ions on the surface of the δ-MnO2 that is a host of Pt was examined as a model reaction. The δ-MnO2 sorbing Pt was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) to determine the chemical state of the Pt. Hydrolytic Pt(II) complex ions were specifically sorbed above pH 6 by the formation of a Mn-O-Pt bond. XPS spectra and XANES spectra for δ-MnO2 sorbing Pt showed that the sorbed Pt(II) was oxidized to Pt(IV) on δ-MnO2. The extended X-ray absorption fine structure (EXAFS) analysis showed that the coordination structure of Pt sorbed on δ-MnO2 is almost the same as that of the [Pt(OH)6]2- complex ion used as a standard. Therefore, the mechanism for the concentration of Pt in marine ferromanganese crust may be an oxidative substitution (penetration of Pt(IV) into structure of δ-MnO2) by a reduction-oxidation reaction between Pt(II) in [PtCl4-n(OH)n]2- and Mn(IV) in δ-MnO2 through a Mn-O-Pt bond.

Spectroscopic studies of U(VI) sorption at the kaolinite-water interface. Final report

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

Thompson, H.A.; Parks, G.A.; Brown, G.E. Jr.

Efficient use of U as a resource and safe handling, recycling and disposal of U-containing wastes require an understanding of the factors controlling the fate of U, where fate refers to the destination of U, typically expressed as an environmental medium or a process phase. The sorption process constitutes a change in elemental fate. Partitioning of an element from solution to a solid phase, or sorption, can be divided into three broad categories: adsorption, surface precipitation, and absorption. Extended X-ray absorption fine structure (EXAFS), a type of X-ray absorption spectroscopy (XAS), offers the possibility for distinguishing among different modes ofmore » sorption by characterizing the atomic environment of the sorbing element. In this study, the authors use EXAFS to determine the structure of U(VI) sorption complexes at the kaolinite-water interface. In Chapter One, they present an overview of selected aspects of U structural chemistry as a basis for considering the structural environment of U at the solid-water interface. To evaluate the utility of XAS for characterization of the structural environment of U(VI) at the solid-water interface, they have carried out an in-depth analysis of XAS data from U(VI)-containing solid and solution model compounds, which they describe in Chapter Two. In Chapter three, they consider sorption of U by kaolinite as a means of effecting the removal of U from surface collection pond waters on the Rocky Flats Plant site in northern Colorado.« less

Effects of Fine-Scale Landscape Variability on Satellite-Derived Land Surface Temperature Products Over Sparse Vegetation Canopies

NASA Astrophysics Data System (ADS)

Powell, R. L.; Goulden, M.; Peterson, S.; Roberts, D. A.; Still, C. J.

2015-12-01

Temperature is a primary environmental control on biological systems and processes at a range of spatial and temporal scales, from controlling biochemical processes such as photosynthesis to influencing continental-scale species distribution. The Landsat satellite series provides a long record (since the mid-1980s) of relatively high spatial resolution thermal infrared (TIR) imagery, from which we derive land surface temperature (LST) grids. Here, we investigate fine spatial resolution factors that influence Landsat-derived LST over a spectrally and spatially heterogeneous landscape. We focus on paired sites (inside/outside a 1994 fire scar) within a pinyon-juniper scrubland in Southern California. The sites have nearly identical micro-meteorology and vegetation species composition, but distinctly different vegetation abundance and structure. The tower at the unburned site includes a number of in-situ imaging tools to quantify vegetation properties, including a thermal camera on a pan-tilt mount, allowing hourly characterization of landscape component temperatures (e.g., sunlit canopy, bare soil, leaf litter). We use these in-situ measurements to assess the impact of fine-scale landscape heterogeneity on estimates of LST, including sensitivity to (i) the relative abundance of component materials, (ii) directional effects due to solar and viewing geometry, (iii) duration of sunlit exposure for each compositional type, and (iv) air temperature. To scale these properties to Landsat spatial resolution (~100-m), we characterize the sub-pixel composition of landscape components (in addition to shade) by applying spectral mixture analysis (SMA) to the Landsat Operational Land Imager (OLI) spectral bands and test the sensitivity of the relationships established with the in-situ data at this coarser scale. The effects of vegetation abundance and cover height versus other controls on satellite-derived estimates of LST will be assessed by comparing estimates at the burned vs. unburned sites across multiple seasons (~30 dates).

Fine-Scale Skeletal Banding Can Distinguish Symbiotic from Asymbiotic Species among Modern and Fossil Scleractinian Corals.

PubMed

Frankowiak, Katarzyna; Kret, Sławomir; Mazur, Maciej; Meibom, Anders; Kitahara, Marcelo V; Stolarski, Jarosław

2016-01-01

Understanding the evolution of scleractinian corals on geological timescales is key to predict how modern reef ecosystems will react to changing environmental conditions in the future. Important to such efforts has been the development of several skeleton-based criteria to distinguish between the two major ecological groups of scleractinians: zooxanthellates, which live in symbiosis with dinoflagellate algae, and azooxanthellates, which lack endosymbiotic dinoflagellates. Existing criteria are based on overall skeletal morphology and bio/geo-chemical indicators-none of them being particularly robust. Here we explore another skeletal feature, namely fine-scale growth banding, which differs between these two groups of corals. Using various ultra-structural imaging techniques (e.g., TEM, SEM, and NanoSIMS) we have characterized skeletal growth increments, composed of doublets of optically light and dark bands, in a broad selection of extant symbiotic and asymbiotic corals. Skeletons of zooxanthellate corals are characterized by regular growth banding, whereas in skeletons of azooxanthellate corals the growth banding is irregular. Importantly, the regularity of growth bands can be easily quantified with a coefficient of variation obtained by measuring bandwidths on SEM images of polished and etched skeletal surfaces of septa and/or walls. We find that this coefficient of variation (lower values indicate higher regularity) ranges from ~40 to ~90% in azooxanthellate corals and from ~5 to ~15% in symbiotic species. With more than 90% (28 out of 31) of the studied corals conforming to this microstructural criterion, it represents an easy and robust method to discriminate between zooxanthellate and azooxanthellate corals. This microstructural criterion has been applied to the exceptionally preserved skeleton of the Triassic (Norian, ca. 215 Ma) scleractinian Volzeia sp., which contains the first example of regular, fine-scale banding of thickening deposits in a fossil coral of this age. The regularity of its growth banding strongly suggests that the coral was symbiotic with zooxanthellates.

Fine-Scale Skeletal Banding Can Distinguish Symbiotic from Asymbiotic Species among Modern and Fossil Scleractinian Corals

PubMed Central

Frankowiak, Katarzyna; Kret, Sławomir; Mazur, Maciej; Meibom, Anders; Kitahara, Marcelo V.; Stolarski, Jarosław

2016-01-01

Understanding the evolution of scleractinian corals on geological timescales is key to predict how modern reef ecosystems will react to changing environmental conditions in the future. Important to such efforts has been the development of several skeleton-based criteria to distinguish between the two major ecological groups of scleractinians: zooxanthellates, which live in symbiosis with dinoflagellate algae, and azooxanthellates, which lack endosymbiotic dinoflagellates. Existing criteria are based on overall skeletal morphology and bio/geo-chemical indicators—none of them being particularly robust. Here we explore another skeletal feature, namely fine-scale growth banding, which differs between these two groups of corals. Using various ultra-structural imaging techniques (e.g., TEM, SEM, and NanoSIMS) we have characterized skeletal growth increments, composed of doublets of optically light and dark bands, in a broad selection of extant symbiotic and asymbiotic corals. Skeletons of zooxanthellate corals are characterized by regular growth banding, whereas in skeletons of azooxanthellate corals the growth banding is irregular. Importantly, the regularity of growth bands can be easily quantified with a coefficient of variation obtained by measuring bandwidths on SEM images of polished and etched skeletal surfaces of septa and/or walls. We find that this coefficient of variation (lower values indicate higher regularity) ranges from ~40 to ~90% in azooxanthellate corals and from ~5 to ~15% in symbiotic species. With more than 90% (28 out of 31) of the studied corals conforming to this microstructural criterion, it represents an easy and robust method to discriminate between zooxanthellate and azooxanthellate corals. This microstructural criterion has been applied to the exceptionally preserved skeleton of the Triassic (Norian, ca. 215 Ma) scleractinian Volzeia sp., which contains the first example of regular, fine-scale banding of thickening deposits in a fossil coral of this age. The regularity of its growth banding strongly suggests that the coral was symbiotic with zooxanthellates. PMID:26751803

Quercetagetin-Loaded Zein-Propylene Glycol Alginate Ternary Composite Particles Induced by Calcium Ions: Structure Characterization and Formation Mechanism.

PubMed

Sun, Cuixia; Wei, Yang; Li, Ruirui; Dai, Lei; Gao, Yanxiang

2017-05-17

The complexation of zein and propylene glycol alginate (PGA) was confirmed to improve the entrapment efficiency and loading capacity of quercetagetin (Q) in our previous study. The present work focused on the influence and induction mechanism of calcium ions on structures of Q-loaded zein-PGA ternary composite particles. The incorporation of Ca 2+ resulted in the formation of aggregates with a large dimension between zein particles, led to obvious conformational, secondary, and tertiary structural changes of zein, and caused the disappearance of crystalline structure of zein. PGA exhibited a fine filamentous network structure and became much thicker and stronger in the presence of Ca 2+ . The presence of Q promoted the affinity and binding capacity of Ca 2+ to zein and PGA. An interwoven network structure with enhanced firmness and density was observed in Q-loaded zein-PGA composite particles, leading to improved thermal stability. Three potential mechanisms were proposed to explain the structural characteristics induced by Ca 2+ , including particle-particle collision for zein particles, chain-chain association for PGA molecules, and simultaneous cross-linking coupled with aggregating for Q-loaded zein-PGA composite particles.

The use of C-near edge X-ray absorption fine structure spectroscopy for the elaboration of chemistry in lignocellulosics

Treesearch

Lucian A. Lucia; Hiroki Nanko; Alan W. Rudie; Doug G. Mancosky; Sue Wirick

2006-01-01

The research presented elucidates the oxidation chemistry occurring in hydrogen peroxide bleached kraft pulp fibers by employing carbon near edge x-ray absorption fine structure spectroscopy (C-NEXAFS). C-NEXAFS is a soft x-ray technique that selectively interrogates atomic moieties using photoelectrons (Xrays) of variable energies. The X1A beam line at the National...

A New Multibeam Sonar Technique for Evaluating Fine-Scale Fish Behavior Near Hydroelectric Dam Guidance Structures

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

Johnson, Robert L.; Simmons, Mary Ann; Simmons, Carver S.

2002-03-07

This book chapter describes a Dual-Head Multibeam Sonar (DHMS) system developed by Battelle and deployed at two dam sites on the Snake and Columbia rivers in Washington State to evaluate the fine-scale (

Simple Model with Time-Varying Fine-Structure ``Constant''

NASA Astrophysics Data System (ADS)

Berman, M. S.

2009-10-01

Extending the original version written in colaboration with L.A. Trevisan, we study the generalisation of Dirac's LNH, so that time-variation of the fine-structure constant, due to varying electrical and magnetic permittivities is included along with other variations (cosmological and gravitational ``constants''), etc. We consider the present Universe, and also an inflationary scenario. Rotation of the Universe is a given possibility in this model.

Accuracy of mapping the Earth's gravity field fine structure with a spaceborne gravity gradiometer mission

NASA Technical Reports Server (NTRS)

Kahn, W. D.

1984-01-01

The spaceborne gravity gradiometer is a potential sensor for mapping the fine structure of the Earth's gravity field. Error analyses were performed to investigate the accuracy of the determination of the Earth's gravity field from a gravity field satellite mission. The orbital height of the spacecraft is the dominating parameter as far as gravity field resolution and accuracies are concerned.

Structural Changes Correlated with Magnetic Spin State Isomorphism in the S2 State of the Mn4CaO5 Cluster in the Oxygen-Evolving Complex of Photosystem II

PubMed Central

Chatterjee, Ruchira; Han, Guangye; Kern, Jan; Gul, Sheraz; Fuller, Franklin D.; Garachtchenko, Anna; Young, Iris; Weng, Tsu-Chien; Nordlund, Dennis; Alonso-Mori, Roberto; Bergmann, Uwe; Sokaras, Dimosthenis; Hatakeyama, Makoto; Yachandra, Vittal K.; Yano, Junko

2016-01-01

The Mn4CaO5 cluster in Photosystem II catalyzes the four-electron redox reaction of water oxidation in natural photosynthesis. This catalytic reaction cycles through four intermediate states (Si, i = 0 to 4), involving changes in the redox state of the four Mn atoms in the cluster. Recent studies suggest the presence and importance of isomorphous structures within the same redox/intermediate S-state. It is highly likely that geometric and electronic structural flexibility play a role in the catalytic mechanism. Among the catalytic intermediates that have been identified experimentally thus far, there is clear evidence of such isomorphism in the S2 state, with a high-spin (5/2) (HS) and a low spin (1/2) (LS) form, identified and characterized by their distinct electron paramagnetic resonance (EPR spectroscopy) signals. We studied these two S2 isomers with Mn extended X-ray absorption fine structure (EXAFS) and absorption and emission spectroscopy (XANES/XES) to characterize the structural and electronic structural properties. The geometric and electronic structure of the HS and LS S2 states are different as determined using Mn EXAFS and XANES/XES, respectively. The Mn K-edge XANES and XES for the HS form are different from the LS and indicate a slightly lower positive charge on the Mn atoms compared to the LS form. Based on the EXAFS results which are clearly different, we propose possible structural differences between the two spin states. Such structural and magnetic redox-isomers if present at room temperature, will likely play a role in the mechanism for water-exchange/oxidation in photosynthesis. PMID:28044099

Structural changes correlated with magnetic spin state isomorphism in the S 2 state of the Mn 4CaO 5 cluster in the oxygen-evolving complex of photosystem II

DOE PAGES

Chatterjee, Ruchira; Han, Guangye; Kern, Jan; ...

2016-05-09

The Mn 4CaO 5 cluster in photosystem II catalyzes the four-electron redox reaction of water oxidation in natural photosynthesis. This catalytic reaction cycles through four intermediate states (S i, i = 0 to 4), involving changes in the redox state of the four Mn atoms in the cluster. Recent studies suggest the presence and importance of isomorphous structures within the same redox/intermediate S-state. It is highly likely that geometric and electronic structural flexibility play a role in the catalytic mechanism. Among the catalytic intermediates that have been identified experimentally thus far, there is clear evidence of such isomorphism in themore » S2 state, with a high-spin (5/2) (HS) and a low spin (1/2) (LS) form, identified and characterized by their distinct electron paramagnetic resonance (EPR spectroscopy) signals. We studied these two S2 isomers with Mn extended X-ray absorption fine structure (EXAFS) and absorption and emission spectroscopy (XANES/XES) to characterize the structural and electronic structural properties. The geometric and electronic structure of the HS and LS S2 states are different as determined using Mn EXAFS and XANES/XES, respectively. The Mn K-edge XANES and XES for the HS form are different from the LS and indicate a slightly lower positive charge on the Mn atoms compared to the LS form. Based on the EXAFS results which are clearly different, we propose possible structural differences between the two spin states. As a result, such structural and magnetic redox-isomers if present at room temperature, will likely play a role in the mechanism for water-exchange/oxidation in photosynthesis.« less

Mechanical Characterization of High-Performance Steel-Fiber Reinforced Cement Composites with Self-Healing Effect

PubMed Central

Kim, Dong Joo; Kang, Seok Hee; Ahn, Tae-Ho

2014-01-01

The crack self-healing behavior of high-performance steel-fiber reinforced cement composites (HPSFRCs) was investigated. High-strength deformed steel fibers were employed in a high strength mortar with very fine silica sand to decreasing the crack width by generating higher interfacial bond strength. The width of micro-cracks, strongly affected by the type of fiber and sand, clearly produced the effects on the self-healing behavior. The use of fine silica sand in HPSFRCs with high strength deformed steel fibers successfully led to rapid healing owing to very fine cracks with width less than 20 μm. The use of very fine silica sand instead of normal sand produced 17%–19% higher tensile strength and 51%–58% smaller width of micro-cracks. PMID:28788471

Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

PubMed Central

Moritake, Y.; Kanamori, Y.; Hane, K.

2016-01-01

We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers. PMID:27622503

The impact of mating systems and dispersal on fine-scale genetic structure at maternally, paternally and biparentally inherited markers.

PubMed

Shaw, Robyn E; Banks, Sam C; Peakall, Rod

2018-01-01

For decades, studies have focused on how dispersal and mating systems influence genetic structure across populations or social groups. However, we still lack a thorough understanding of how these processes and their interaction shape spatial genetic patterns over a finer scale (tens-hundreds of metres). Using uniparentally inherited markers may help answer these questions, yet their potential has not been fully explored. Here, we use individual-level simulations to investigate the effects of dispersal and mating system on fine-scale genetic structure at autosomal, mitochondrial and Y chromosome markers. Using genetic spatial autocorrelation analysis, we found that dispersal was the major driver of fine-scale genetic structure across maternally, paternally and biparentally inherited markers. However, when dispersal was restricted (mean distance = 100 m), variation in mating behaviour created strong differences in the comparative level of structure detected at maternally and paternally inherited markers. Promiscuity reduced spatial genetic structure at Y chromosome loci (relative to monogamy), whereas structure increased under polygyny. In contrast, mitochondrial and autosomal markers were robust to differences in the specific mating system, although genetic structure increased across all markers when reproductive success was skewed towards fewer individuals. Comparing males and females at Y chromosome vs. mitochondrial markers, respectively, revealed that some mating systems can generate similar patterns to those expected under sex-biased dispersal. This demonstrates the need for caution when inferring ecological and behavioural processes from genetic results. Comparing patterns between the sexes, across a range of marker types, may help us tease apart the processes shaping fine-scale genetic structure. © 2017 John Wiley & Sons Ltd.

13C NMR spectroscopy characterization of particle-size fractionated soil organic carbon in subalpine forest and grassland ecosystems.

PubMed

Shiau, Yo-Jin; Chen, Jenn-Shing; Chung, Tay-Lung; Tian, Guanglong; Chiu, Chih-Yu

2017-12-01

Soil organic carbon (SOC) and carbon (C) functional groups in different particle-size fractions are important indicators of microbial activity and soil decomposition stages under wildfire disturbances. This research investigated a natural Tsuga forest and a nearby fire-induced grassland along a sampling transect in Central Taiwan with the aim to better understand the effect of forest wildfires on the change of SOC in different soil particle scales. Soil samples were separated into six particle sizes and SOC was characterized by solid-state 13 C nuclear magnetic resonance spectroscopy in each fraction. The SOC content was higher in forest than grassland soil in the particle-size fraction samples. The O-alkyl-C content (carbohydrate-derived structures) was higher in the grassland than the forest soils, but the alkyl-C content (recalcitrant substances) was higher in forest than grassland soils, for a higher humification degree (alkyl-C/O-alkyl-C ratio) in forest soils for all the soil particle-size fractions. High humification degree was found in forest soils. The similar aromaticity between forest and grassland soils might be attributed to the fire-induced aromatic-C content in the grassland that offsets the original difference between the forest and grassland. High alkyl-C content and humification degree and low C/N ratios in the fine particle-size fractions implied that undecomposed recalcitrant substances tended to accumulate in the fine fractions of soils.

Photoionization of ground and excited levels of P II

NASA Astrophysics Data System (ADS)

Nahar, Sultana N.

2017-01-01

Photoionization cross section (σPI) of P II, (hν + P II → P III + e), from ground and a large number of excited levels are presented. The study includes the resonant structures and the characteristics of the background in photoionization cross sections. The present calculations were carried out in the Breit-Pauli R-matrix (BPRM) method that includes relativistic effects. The autoionizing resonances are delineated with a fine energy mesh to observe the fine structure effects. A singular resonance, formed by the coupling of channels in fine structure but not allowed in LS coupling, is seen at the ionization threshold of photoionization for the ground and many excited levels. The background cross section is seen enhanced compared to smooth decay for the excited levels. Examples are presented to illustrate the enhanced background cross sections at the energies of the core levels, 4P3/2 and 2D3/2, that are allowed for electric dipole transitions by the core ground level 2 P1/2o. In addition strong Seaton or photo-excitation-of-core (PEC) resonances are found in the photoionization of single valence electron excited levels. Calculations used a close coupling wave function expansion that included 18 fine structure levels of core P III from configurations 3s23p, 3s3p2, 3s23d, 3s24s, 3s24p and 3p3. Photoionization cross sections are presented for all 475 fine structure levels of P II found with n ≤ 10 and l ≤ 9. The present results will provide high precision parameters of various applications involving this less studied ion.

Counting individual sulfur atoms in a protein by ultrahighresolution Fourier transform ion cyclotron resonance mass spectrometry: Experimental resolution of isotopic fine structure in proteins

PubMed Central

Shi, Stone D.-H.; Hendrickson, Christopher L.; Marshall, Alan G.

1998-01-01

A typical molecular ion mass spectrum consists of a sum of signals from species of various possible isotopic compositions. Only the monoisotopic peak (e.g., all carbons are 12C; all nitrogens are 14N, etc.) has a unique elemental composition. Every other isotope peak at approximately integer multiples of ∼1 Da higher in nominal mass represents a sum of contributions from isotope combinations differing by a few mDa (e.g., two 13C vs. two 15N vs. one 13C and one 15N vs. 34S, vs. 18O, etc., at ∼2 Da higher in mass than the monoisotopic mass). At sufficiently high mass resolving power, each of these nominal-mass peaks resolves into its isotopic fine structure. Here, we report resolution of the isotopic fine structure of proteins up to 15.8 kDa (isotopic 13C,15N doubly depleted tumor suppressor protein, p16), made possible by electrospray ionization followed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass analysis at 9.4 tesla. Further, a resolving power of m/Δm50% ≈8,000,000 has been achieved on bovine ubiquitin (8.6 kDa). These results represent a 10-fold increase in the highest mass at which isotopic fine structure previously had been observed. Finally, because isotopic fine structure reveals elemental composition directly, it can be used to confirm or determine molecular formula. For p16, for example, we were able to determine (5.1 ± 0.3) the correct number (five) of sulfur atoms solely from the abundance ratio of the resolved 34S peak to the monoisotopic peak. PMID:9751700

Determinants of fish assemblage structure in Northwestern Great Plains streams

USGS Publications Warehouse

Mullen, J.A.; Bramblett, R.G.; Guy, C.S.; Zale, A.V.; Roberts, D.W.

2011-01-01

Prairie streams are known for their harsh and stochastic physical conditions, and the fish assemblages therein have been shown to be temporally variable. We assessed the spatial and temporal variation in fish assemblage structure in five intermittent, adventitious northwestern Great Plains streams representing a gradient of watershed areas. Fish assemblages and abiotic conditions varied more spatially than temporally. The most important variables explaining fish assemblage structure were longitudinal position and the proportion of fine substrates. The proportion of fine substrates increased proceeding upstream, approaching 100% in all five streams, and species richness declined upstream with increasing fine substrates. High levels of fine substrate in the upper reaches appeared to limit the distribution of obligate lithophilic fish species to reaches further downstream. Species richness and substrates were similar among all five streams at the lowermost and uppermost sites. However, in the middle reaches, species richness increased, the amount of fine substrate decreased, and connectivity increased as watershed area increased. Season and some dimensions of habitat (including thalweg depth, absolute distance to the main-stem river, and watershed size) were not essential in explaining the variation in fish assemblages. Fish species richness varied more temporally than overall fish assemblage structure did because common species were consistently abundant across seasons, whereas rare species were sometimes absent or perhaps not detected by sampling. The similarity in our results among five streams varying in watershed size and those from other studies supports the generalization that spatial variation exceeds temporal variation in the fish assemblages of prairie and warmwater streams. Furthermore, given longitudinal position, substrate, and stream size, general predictions regarding fish assemblage structure and function in prairie streams are possible. ?? American Fisheries Society 2011.

Microstructural and petrophysical characterization of a "structurally oversimplified" fault zone in poorly lithified sands: evidence for a coseismic rupture?

NASA Astrophysics Data System (ADS)

Balsamo, Fabrizio; Storti, Fabrizio

2010-05-01

We studied an extensional fault zone developed in poorly lithified, quartz-rich high porosity sandy sediments of the seismically active Crotone basin (southern Italy). The fault zone cuts across interlayered fine- to coarse-grained sands and consists of a cm-thick, discrete fault core embedded in virtually undeformed wall sediments. Consequently, it can be described as "structurally oversimplified" due to the lack of footwall and hanging wall damage zones. We acquired microstructural, grain size, grain shape, porosity, mineralogical and permeability data to investigate the influence of initial sedimentological characteristics of sands on the final faulted granular products and related hydrologic properties. Faulting evolves by a general grain size and porosity reduction with a combination of intragranular fracturing, spalling, and flaking of grain edges, irrespective of grain mineralogy. The dominance of cataclasis, also confirmed by fractal dimensions >2.6, is generally not expected at a deformation depth <1 km. Coarse-grained sand shows a much higher comminution intensity, grain shape variations and permeability drop than fine-grained sands. This is because coarser aggregates have (i) fewer grain-to-grain contacts for a given area, which results in higher stress concentration at contact points, and (ii) a higher probability of pre-existing intragranular microstructural defects that result in a lower grain strength. The peculiar structural architecture, the dominance of cataclasis over non-destructive particulate flow, and the compositional variations of clay minerals in the fault core, strongly suggest that the studied fault zone developed by a coseismic rupture.

Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy.

PubMed

Lin, Liang; Pang, Zhiyong; Fang, Shaojie; Wang, Fenggong; Song, Shumei; Huang, Yuying; Wei, Xiangjun; Yu, Haisheng; Han, Shenghao

2011-02-10

The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.

Structure and mechanical characterization of Mg-Nd-Zn alloys prepared by different processes

NASA Astrophysics Data System (ADS)

Dvorský, D.; Kubásek, J.; Vojtěch, D.; Voňavková, I.; Veselý, M.; Čavojský, M.

2017-02-01

Magnesium alloys containing about 3 wt. % of Nd and 0.5 wt. % of Zn are considered as promising materials for application in transport and medical industry. Properly treated materials can reach ultimate tensile strength (UTS) higher than 300 MPa. Also the corrosion resistance of these alloys is superior to many other magnesium-based materials. Present work is focused on the preparation of Mg-3Nd-0.5Zn magnesium alloy by classical casting and subsequent thermal treatment. As-cast material was extruded at 400 °C, with extrusion ratio equal to 16 and velocity of 0.2 mm/s. The effect of thermal treatment and also strong plastic deformation during extrusion on final structure conditions and mechanical properties is specified. Present results confirm significant improvement of tensile yield strength (TYS) and UTS after extrusion process as a consequence of fine-grained structure combined with precipitation strengthening. Beside, texture strengthening in the direction parallel to the extrusion has been observed too.

Ab initio studies of isolated boron substitutional defects in graphane

NASA Astrophysics Data System (ADS)

Mapasha, R. E.; Chetty, N.

2017-10-01

We have systematically studied energetics, structural and electronic properties of different configurations of the B atoms substituting C-H pairs located on a single hexagonal ring in a graphane system using the first-principles density functional theory (DFT). A total number of 12 distinct B dopants configurations were identified and characterized. Based on the formation energy analysis, we found that relative stability of B dopants depends greatly on the defect configurations. Our results suggest that the B substitutions prefer to be distributed randomly but avoiding the formation of homo-elemental B-B bonds in a graphane system, at any concentration. Generally, the values of band gap decrease as the number of B dopants increases, but the low energy configurations have large band gaps compared to those that have homo-elemental bonds. As a result, the band gap of graphane can be fine tuned through the change in the structural arrangement of B atoms. The adequate control of the electronic structure of graphane through doping should be essential for technological device applications.

Spin interactions in InAs quantum dots

NASA Astrophysics Data System (ADS)

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

2006-03-01

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

Measuring h /mCs and the Fine Structure Constant with Bragg Diffraction and Bloch Oscillations

NASA Astrophysics Data System (ADS)

Parker, Richard

2016-05-01

We have demonstrated a new scheme for atom interferometry based on large-momentum-transfer Bragg beam splitters and Bloch oscillations. In this new scheme, we have achieved a resolution of δα / α =0.25ppb in the fine structure constant measurement, which gives up to 4.4 million radians of phase difference between freely evolving matter waves. We suppress many systematic effects, e.g., Zeeman shifts and effects from Earth's gravity and vibrations, use Bloch oscillations to increase the signal and reduce the diffraction phase, simulate multi-atom Bragg diffraction to understand sub-ppb systematic effects, and implement spatial filtering to further suppress systematic effects. We present our recent progress toward a measurement of the fine structure constant, which will provide a stringent test of the standard model of particle physics.

Porous-electrode preparation method

DOEpatents

Arons, R.M.; Dusek, J.T.

1981-09-17

A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity.

Porous electrode preparation method

DOEpatents

Arons, Richard M.; Dusek, Joseph T.

1983-01-01

A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity.

Porous electrode preparation method

DOEpatents

Arons, R.M.; Dusek, J.T.

1983-10-18

A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity. 2 figs.

Optimal Design of Experiments by Combining Coarse and Fine Measurements

NASA Astrophysics Data System (ADS)

Lee, Alpha A.; Brenner, Michael P.; Colwell, Lucy J.

2017-11-01

In many contexts, it is extremely costly to perform enough high-quality experimental measurements to accurately parametrize a predictive quantitative model. However, it is often much easier to carry out large numbers of experiments that indicate whether each sample is above or below a given threshold. Can many such categorical or "coarse" measurements be combined with a much smaller number of high-resolution or "fine" measurements to yield accurate models? Here, we demonstrate an intuitive strategy, inspired by statistical physics, wherein the coarse measurements are used to identify the salient features of the data, while the fine measurements determine the relative importance of these features. A linear model is inferred from the fine measurements, augmented by a quadratic term that captures the correlation structure of the coarse data. We illustrate our strategy by considering the problems of predicting the antimalarial potency and aqueous solubility of small organic molecules from their 2D molecular structure.

Preparation and characterization of collagen-hydroxyapatite/pectin composite.

PubMed

Wenpo, Feng; Gaofeng, Liang; Shuying, Feng; Yuanming, Qi; Keyong, Tang

2015-03-01

Pectin, a kind of plant polysaccharide, was introduced into collagen-hydroxyapatite composite system, and prepared collagen-hydroxyapatite/pectin (Col-HA/pectin) composite in situ. The structure of the composite was investigated by XRD, SEM, and FT-IR. The mechanical properties, water absorption, enzyme degradation, and cytotoxicity of the composite were investigated as well. The results show that the inorganic substance in the composite materials is hydroxyapatite in relatively low crystallinity. A new interface appeared by the interaction among hydroxyapatite and collagen-pectin, and formed smooth fine particles. The mechanical properties, water absorption, enzyme degradation, and cytotoxicity indicate a potential use in bone replacement for the new composite. Copyright © 2014 Elsevier B.V. All rights reserved.

Studies of the Si/SiO2 interface using synchrotron radiation

NASA Technical Reports Server (NTRS)

Hecht, M. H.; Grunthaner, F. J.

1985-01-01

Synchrotron radiation photoemission spectroscopy (SRPS) in the 1-4 KeV photon energy range is a useful tool for interface characterization. Results are presented of a series of studies of the near-interface region of Si/SiO2 which confirm that a bond strain gradient exists in the oxide as a result of lattice mismatch. These experiments include measurement of photoemission lineshape changes as a function of photon energy, corresponding changes in the electron escape depth near the interface, and surface extended X-ray absorption fine structure (SEXAFS) measurements directly indicating the shortening of the Si-Si second nearest neighbor distance in the near-interface region of the oxide.

A genetic atlas of human admixture history.

PubMed

Hellenthal, Garrett; Busby, George B J; Band, Gavin; Wilson, James F; Capelli, Cristian; Falush, Daniel; Myers, Simon

2014-02-14

Modern genetic data combined with appropriate statistical methods have the potential to contribute substantially to our understanding of human history. We have developed an approach that exploits the genomic structure of admixed populations to date and characterize historical mixture events at fine scales. We used this to produce an atlas of worldwide human admixture history, constructed by using genetic data alone and encompassing over 100 events occurring over the past 4000 years. We identified events whose dates and participants suggest they describe genetic impacts of the Mongol empire, Arab slave trade, Bantu expansion, first millennium CE migrations in Eastern Europe, and European colonialism, as well as unrecorded events, revealing admixture to be an almost universal force shaping human populations.

On groupoid gradings

NASA Astrophysics Data System (ADS)

Calderón Martín, Antonio Jesús; Martín González, Cándido; Ndoye, Daouda

2018-01-01

We introduce the notion of groupoid grading, give some nontrivial examples and prove that groupoid gradings on simple commutative or anti-commutative algebras are necessarily group gradings. We also take advantage of the structure of groupoids to prove some results about groupoid gradings and certain coarsenings of these which turn out to be group gradings. We also study set gradings on arbitrary algebras, by characterizing their homogeneous semisimplicity and their homogeneous simplicity in terms of a property satisfied by the supports of the gradings, and also relate set gradings with groupoid gradings via coarsenings. Finally we study a class of set gradings on Mn(C) , the orthogonal gradings, and show that all of them which are fine are necessarily groupoid gradings.

An EXAFS study of zinc coordination in microbial cells.

PubMed

Webb, S M; Gaillard, J F; Jackson, B E; Stahl, D A

2001-03-01

Five microbes were isolated from metal amended enrichment cultures derived from the sediments of a lake contaminated by a zinc smelter. Each of these organisms was grown in pure culture in the presence of zinc. Quick Extended X-ray Absorption Fine Structure (QEXAFS) spectroscopy was used to investigate the average coordination environment of the zinc associated with the microbial biomass. Fitting of the first coordination shell of zinc shows that significant differences exist for each microbial species examined. The coordination environment of zinc varies between sulfurs to six-fold nitrogen/oxygen. with two microbial strains showing mixed coordination shells. Further study is required in order to characterize these sites and their locations within the cell.

Fine mapping and characterization of candidate genes that control resistance to Cercospora Sojina K. Hara in two soybean germplasm accessions

USDA-ARS?s Scientific Manuscript database

In order to fine map the novel FLS resistance gene(s) in two PIs, PI 594891 and PI 594774, F2:3 seeds from the crosses Blackhawk (FLS susceptible genotype) ×PI 594891, and Blackhawk ×PI 594774 were genotyped with KASP markers that were designed based on the SoySNP 50k Infinium Chip data to identi...

In Situ Characterization of Point-of-Discharge Fine Particulate Emissions

DTIC Science & Technology

2008-07-01

of Point- of -Discharge Fine Particulate Emissions 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6... NUMBER OF PAGES 163 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form... number of weapons systems. A number of Ft. Sill’s training ranges were projected to be in use during the last half of March, 2007 through

Fine Scale Baleen Whale Behavior Observed Via Tagging Over Daily Time Scales

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Fine Scale Baleen Whale Behavior Observed Via Tagging...followed over time scales of days from an oceanographic vessel so that environmental sampling can be conducted in proximity to the tagged whale ...characterize the relationship between diel variability in the foraging behavior of baleen whales (North Atlantic right whales and sei whales ) and the

High-performance Chinese multiclass traffic sign detection via coarse-to-fine cascade and parallel support vector machine detectors

NASA Astrophysics Data System (ADS)

Chang, Faliang; Liu, Chunsheng

2017-09-01

The high variability of sign colors and shapes in uncontrolled environments has made the detection of traffic signs a challenging problem in computer vision. We propose a traffic sign detection (TSD) method based on coarse-to-fine cascade and parallel support vector machine (SVM) detectors to detect Chinese warning and danger traffic signs. First, a region of interest (ROI) extraction method is proposed to extract ROIs using color contrast features in local regions. The ROI extraction can reduce scanning regions and save detection time. For multiclass TSD, we propose a structure that combines a coarse-to-fine cascaded tree with a parallel structure of histogram of oriented gradients (HOG) + SVM detectors. The cascaded tree is designed to detect different types of traffic signs in a coarse-to-fine process. The parallel HOG + SVM detectors are designed to do fine detection of different types of traffic signs. The experiments demonstrate the proposed TSD method can rapidly detect multiclass traffic signs with different colors and shapes in high accuracy.

Limited Effects of Variable-Retention Harvesting on Fungal Communities Decomposing Fine Roots in Coastal Temperate Rainforests.

PubMed

Philpott, Timothy J; Barker, Jason S; Prescott, Cindy E; Grayston, Sue J

2018-02-01

Fine root litter is the principal source of carbon stored in forest soils and a dominant source of carbon for fungal decomposers. Differences in decomposer capacity between fungal species may be important determinants of fine-root decomposition rates. Variable-retention harvesting (VRH) provides refuge for ectomycorrhizal fungi, but its influence on fine-root decomposers is unknown, as are the effects of functional shifts in these fungal communities on carbon cycling. We compared fungal communities decomposing fine roots (in litter bags) under VRH, clear-cut, and uncut stands at two sites (6 and 13 years postharvest) and two decay stages (43 days and 1 year after burial) in Douglas fir forests in coastal British Columbia, Canada. Fungal species and guilds were identified from decomposed fine roots using high-throughput sequencing. Variable retention had short-term effects on β-diversity; harvest treatment modified the fungal community composition at the 6-year-postharvest site, but not at the 13-year-postharvest site. Ericoid and ectomycorrhizal guilds were not more abundant under VRH, but stand age significantly structured species composition. Guild composition varied by decay stage, with ruderal species later replaced by saprotrophs and ectomycorrhizae. Ectomycorrhizal abundance on decomposing fine roots may partially explain why fine roots typically decompose more slowly than surface litter. Our results indicate that stand age structures fine-root decomposers but that decay stage is more important in structuring the fungal community than shifts caused by harvesting. The rapid postharvest recovery of fungal communities decomposing fine roots suggests resiliency within this community, at least in these young regenerating stands in coastal British Columbia. IMPORTANCE Globally, fine roots are a dominant source of carbon in forest soils, yet the fungi that decompose this material and that drive the sequestration or respiration of this carbon remain largely uncharacterized. Fungi vary in their capacity to decompose plant litter, suggesting that fungal community composition is an important determinant of decomposition rates. Variable-retention harvesting is a forestry practice that modifies fungal communities by providing refuge for ectomycorrhizal fungi. We evaluated the effects of variable retention and clear-cut harvesting on fungal communities decomposing fine roots at two sites (6 and 13 years postharvest), at two decay stages (43 days and 1 year), and in uncut stands in temperate rainforests. Harvesting impacts on fungal community composition were detected only after 6 years after harvest. We suggest that fungal community composition may be an important factor that reduces fine-root decomposition rates relative to those of above-ground plant litter, which has important consequences for forest carbon cycling. Copyright © 2018 American Society for Microbiology.

Effects of Al(3+) doping on the structure and properties of goethite and its adsorption behavior towards phosphate.

PubMed

Li, Wei; Wang, Longjun; Liu, Fan; Liang, Xiaoliang; Feng, Xionghan; Tan, Wenfeng; Zheng, Lirong; Yin, Hui

2016-07-01

Al substitution in goethite is common in soils, and has strong influence on the structure and physicochemical properties of goethite. In this research, a series of Al-doped goethites were synthesized, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The adsorption behavior of these samples towards PO4(3-) was also investigated. Characterization results demonstrated that increasing Al content in goethite led to a reduction in crystallinity, increase in specific surface area (SSA), and morphology change from needle-like to granular. Rietveld structure refinement revealed that the lattice parameter a remained almost constant and b slightly decreased, but c was significantly reduced, and the calculated crystal density increased. EXAFS analysis demonstrated that the Fe(Al)-O distance in the structure of the doped goethites was almost the same, but the Fe-Fe(Al) distance decreased with increasing Al content. Surface analysis showed that, with increasing Al content, the content of OH groups on the mineral surface increased. The adsorption of phosphate per unit mass of Al-doped goethite increased, while adsorption per unit area decreased owing to the decrease of the relative proportion of (110) facets in the total surface area of the minerals. The results of this research facilitate better understanding of the effect of Al substitution on the structure and properties of goethite and the cycling of phosphate in the environment. Copyright © 2016. Published by Elsevier B.V.

Atomic oxygen fine-structure splittings with tunable far-infrared spectroscopy

NASA Technical Reports Server (NTRS)

Zink, Lyndon R.; Evenson, Kenneth M.; Matsushima, Fusakazu; Nelis, Thomas; Robinson, Ruth L.

1991-01-01

Fine-structure splittings of atomic oxygen (O-16) in the ground state have been accurately measured using a tunable far-infrared spectrometer. The 3P0-3pl splitting is 2,060,069.09 (10) MHz, and the 3Pl-3P2 splitting is 4,744,777.49 (16) MHz. These frequencies are important for measuring atomic oxygen concentration in earth's atmosphere and the interstellar medium.

Novel visualization studies of lignocellulosic oxidation chemistry by application of C-near edge X-ray absorption fine structure spectroscopy

Treesearch

Douglas G. Mancosky; Lucian A. Lucia; Hiroki Nanko; Sue Wirick; Alan W. Rudie; Robert Braun

2005-01-01

The research presented herein is the first attempt to probe the chemical nature of lignocellulosic samples by the application of carbon near edge X-ray absorption fine structure spectroscopy (C-NEXAFS). C-NEXAFS is a soft X-ray technique that principally provides selective interrogation of discrete atomic moieties using photoelectrons of variable energies. The X1A beam...

A correlational method to concurrently measure envelope and temporal fine structure weights: effects of age, cochlear pathology, and spectral shaping.

PubMed

Fogerty, Daniel; Humes, Larry E

2012-09-01

The speech signal may be divided into spectral frequency-bands, each band containing temporal properties of the envelope and fine structure. This study measured the perceptual weights for the envelope and fine structure in each of three frequency bands for sentence materials in young normal-hearing listeners, older normal-hearing listeners, aided older hearing-impaired listeners, and spectrally matched young normal-hearing listeners. The availability of each acoustic property was independently varied through noisy signal extraction. Thus, the full speech stimulus was presented with noise used to mask six different auditory channels. Perceptual weights were determined by correlating a listener's performance with the signal-to-noise ratio of each acoustic property on a trial-by-trial basis. Results demonstrate that temporal fine structure perceptual weights remain stable across the four listener groups. However, a different weighting typography was observed across the listener groups for envelope cues. Results suggest that spectral shaping used to preserve the audibility of the speech stimulus may alter the allocation of perceptual resources. The relative perceptual weighting of envelope cues may also change with age. Concurrent testing of sentences repeated once on a previous day demonstrated that weighting strategies for all listener groups can change, suggesting an initial stabilization period or susceptibility to auditory training.

Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation

NASA Astrophysics Data System (ADS)

Fauchais, P.; Vardelle, M.; Goutier, S.

2016-12-01

The plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional plasma spraying key points. The second part presents the current knowledge in plasma spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.

Structural study of the ammonium octafluoroneptunate, [NH 4] 4NpF 8

DOE PAGES

Poineau, Frederic; Silva, Chinthaka M.; Yeamans, Charles B.; ...

2016-04-21

The [NH 4] 4NpF 8 salt was prepared from the solid-state reaction of NpO 2 with NH 4HF 2 and characterized by powder X-ray diffraction and X-ray absorption fine structure spectroscopy. The diffraction results confirm the compound to be isostructural to [NH 4] 4UF 8 with the following lattice parameter (a = 13.054(4) Å, b = 6.681(2) Å, c = 13.676(5) Å, ß = 121.14 Å). For the first time, a Neptunium fluoride complex has been characterized by XAFS spectroscopy. The energy position of the white line and inflection of the XANES spectra of [NH 4] 4NpF 8 are consistentmore » with the presence of Np(IV). Adjustment of the EXAFS spectra indicates that the coordination number (7.4±1.5) and the average Np-F distance (2.26(1) Å) are consistent with the presence of the NpF8 dodecahedron. The average Np-F distance is ~0.02 Å shorter than the U-F distance in [NH 4] 4UF 8 and is a result of the actinide contraction.« less

Zebrafish skeleton development: High resolution micro-CT and FIB-SEM block surface serial imaging for phenotype identification

PubMed Central

Silvent, Jeremie; Akiva, Anat; Brumfeld, Vlad; Reznikov, Natalie; Rechav, Katya; Yaniv, Karina; Addadi, Lia; Weiner, Steve

2017-01-01

Although bone is one of the most studied living materials, many questions about the manner in which bones form remain unresolved, including fine details of the skeletal structure during development. In this study, we monitored skeleton development of zebrafish larvae, using calcein fluorescence, high-resolution micro-CT 3D images and FIB-SEM in the block surface serial imaging mode. We compared calcein staining of the skeletons of the wild type and nacre mutants, which are transparent zebrafish, with micro-CT for the first 30 days post fertilization embryos, and identified significant differences. We quantified the bone volumes and mineral contents of bones, including otoliths, during development, and showed that such developmental differences, including otolith development, could be helpful in identifying phenotypes. In addition, high-resolution imaging revealed the presence of mineralized aggregates in the notochord, before the formation of the first bone in the axial skeleton. These structures might play a role in the storage of the mineral. Our results highlight the potential of these high-resolution 3D approaches to characterize the zebrafish skeleton, which in turn could prove invaluable information for better understanding the development and the characterization of skeletal phenotypes. PMID:29220379

Synthesis, characterization and DFT-modeling of novel agents for the protection and restoration of historical calcareous stone substrates.

PubMed

Maiore, Laura; Aragoni, M Carla; Carcangiu, Gianfranco; Cocco, Ombretta; Isaia, Francesco; Lippolis, Vito; Meloni, Paola; Murru, Arianna; Tuveri, Enrica; Arca, Massimiliano

2015-06-15

The ammonium salts of oxamate (AmOxam) and monomethyloxalate (AmMeox), structurally related to ammonium oxalate (AmOx), were synthesized and characterized as protecting agents/filler for calcareous stone substrates. Both compounds featured an improved solubility in water and alcoholic-water mixtures with respect to AmOx. While AmOxam is stable in aqueous solution and reacts with calcite to afford the corresponding insoluble calcium oxamate (CaOxam), AmMeox spontaneously undergoes hydrolysis to give ammonium monohydrogen oxalate hemihydrate (AmBiox) and calcium oxalate (CaOx). Both compounds have been tested for the restoration of naturally weathered marble and biomicritic limestone. The formation of a superficial layer of CaOxam and CaOx was observed on stone samples treated with AmOxam and AmMeox, respectively, depending on the solvent mixture. A quantum-mechanical study was carried out at DFT level in order to investigate the nature of the interactions occurring between the lithic substrate (calcite) and the passivating agents, showing how the structural modifications on oxalic acid derivatives can be exploited to fine-tune their interaction with the calcite surface. Copyright © 2015 Elsevier Inc. All rights reserved.

Characterizing and controlling industrial dust: a case study in small particle measurement.

PubMed

Combes, Richard S; Warren, D Alan

2005-07-01

Instrumentation used to measure characteristics of fine particles entrained in gas or suspended in aerosols provides information needed to develop valid regulations for emission sources and to support the design of control technologies. This case study offers a brief history of "micromeritics," a term used by early researchers to describe the science of small particles, and the related invention of laboratory instruments for characterizing very fine particles. The historical view provides insights into the role that Progressive Era government agencies played in advancing esoteric science and applying this knowledge to the regulation of workplace air pollution. Micromeritics instrumentation developed in conjunction with federal research now has many commercial applications worldwide, with characterizing airborne pollutants only a minor one. However, the continuing advances in the micromeritics field provide important laboratory measurement capabilities to environmental research organizations, such as the National Institute for Occupational Safety and Health (NIOSH).

Clustering of 770,000 genomes reveals post-colonial population structure of North America

NASA Astrophysics Data System (ADS)

Han, Eunjung; Carbonetto, Peter; Curtis, Ross E.; Wang, Yong; Granka, Julie M.; Byrnes, Jake; Noto, Keith; Kermany, Amir R.; Myres, Natalie M.; Barber, Mathew J.; Rand, Kristin A.; Song, Shiya; Roman, Theodore; Battat, Erin; Elyashiv, Eyal; Guturu, Harendra; Hong, Eurie L.; Chahine, Kenneth G.; Ball, Catherine A.

2017-02-01

Despite strides in characterizing human history from genetic polymorphism data, progress in identifying genetic signatures of recent demography has been limited. Here we identify very recent fine-scale population structure in North America from a network of over 500 million genetic (identity-by-descent, IBD) connections among 770,000 genotyped individuals of US origin. We detect densely connected clusters within the network and annotate these clusters using a database of over 20 million genealogical records. Recent population patterns captured by IBD clustering include immigrants such as Scandinavians and French Canadians; groups with continental admixture such as Puerto Ricans; settlers such as the Amish and Appalachians who experienced geographic or cultural isolation; and broad historical trends, including reduced north-south gene flow. Our results yield a detailed historical portrait of North America after European settlement and support substantial genetic heterogeneity in the United States beyond that uncovered by previous studies.

Clustering of 770,000 genomes reveals post-colonial population structure of North America

PubMed Central

Han, Eunjung; Carbonetto, Peter; Curtis, Ross E.; Wang, Yong; Granka, Julie M.; Byrnes, Jake; Noto, Keith; Kermany, Amir R.; Myres, Natalie M.; Barber, Mathew J.; Rand, Kristin A.; Song, Shiya; Roman, Theodore; Battat, Erin; Elyashiv, Eyal; Guturu, Harendra; Hong, Eurie L.; Chahine, Kenneth G.; Ball, Catherine A.

2017-01-01

Despite strides in characterizing human history from genetic polymorphism data, progress in identifying genetic signatures of recent demography has been limited. Here we identify very recent fine-scale population structure in North America from a network of over 500 million genetic (identity-by-descent, IBD) connections among 770,000 genotyped individuals of US origin. We detect densely connected clusters within the network and annotate these clusters using a database of over 20 million genealogical records. Recent population patterns captured by IBD clustering include immigrants such as Scandinavians and French Canadians; groups with continental admixture such as Puerto Ricans; settlers such as the Amish and Appalachians who experienced geographic or cultural isolation; and broad historical trends, including reduced north-south gene flow. Our results yield a detailed historical portrait of North America after European settlement and support substantial genetic heterogeneity in the United States beyond that uncovered by previous studies. PMID:28169989

IR-spectroscopical investigations on the glass structure of porous and sintered compacts of colloidal silica gels

NASA Astrophysics Data System (ADS)

Clasen, Rolf; Hornfeck, M.; Theiss, Wolfgang

1991-08-01

The forming and sintering of fumed silica powders is an interesting route for the preparation of large, very pure or doped silica glasses with a precise geometry. The processing from the shaping of a porous compact to the sintering of transparent silica glass can be successfully investigated with optical spectroscopy. As only the dielectric function DF (a dielectric function is the square root of the complex refractive index) characterizes the material, the vibrational bands were calculated from reflectance measurements. In compacts of fine particles, the topology cannot be neglected. Therefore, the models describing topological effects are briefly reviewed. With these model calculations it could be proven that new bands in the compacts and the significant shifts in the reflectance spectra during sintering are mainly caused by topological effects and that changes in the glass structure play only a secondary role.

Raman and X-Ray Investigation of High-Temperature Methane in the Diamond Anvil Cell

NASA Astrophysics Data System (ADS)

Spaulding, D.; Weck, G.; Loubeyre, P.; Mezouar, M.

2016-12-01

The chemistry and equations of state of simple molecular systems are of extreme importance to planetary astrophysics and for accurate characterization of reaction products and pathways at high pressures and temperatures. Simple molecules such as H2O, CO2 and CH4 are model systems for understanding the effects of pressure on chemical bonding. Here we present recent work to conduct fine-scale studies of the vibrational, chemical and structural properties of CH4 at pressures and temperatures up to 12 GPa and 1000K, with particular attention to behavior in the vicinity of the melting curve. We present results from resistive and laser-heating experiments, coupled with Raman spectroscopy. In addition, high P/T synchrotron powder x-ray diffraction provides tight constraints on melting and solid structure. Our results favor a somewhat higher melting curve and lower dissociative stability limit for the CH4 molecule than other recent work.

Development of ten microsatellite loci in the invasive giant African land snail, Achatina (=Lissachatina) fulica Bowdich, 1822

USGS Publications Warehouse

Morrison, Cheryl L.; Springmann, Marcus J.; Iwanowicz, Deborah D.; Wade, Christopher M.

2015-01-01

A suite of tetra-nucleotide microsatellite loci were developed for the invasive giant African land snail, Achatina (=Lissachatina) fulica Bowdich, 1822, from Ion Torrent next-generation sequencing data. Ten of the 96 primer sets tested amplified consistently in 30 snails from Miami, Florida, plus 12 individuals representative of their native East Africa, Indian and Pacific Ocean regions. The loci displayed moderate levels of allelic diversity (average 5.6 alleles/locus) and heterozygosity (average 42 %). Levels of genetic diversity were sufficient to produce unique multi-locus genotypes and detect phylogeographic structuring among regional samples. The invasive A. fulica can cause extensive damage to important food crops and natural resources, including native flora and fauna. The loci characterized here will be useful for determining the origins and tracking the spread of invasions, detecting fine-scale spatial structuring and estimating demographic parameters.

Clustering of 770,000 genomes reveals post-colonial population structure of North America.

PubMed

Han, Eunjung; Carbonetto, Peter; Curtis, Ross E; Wang, Yong; Granka, Julie M; Byrnes, Jake; Noto, Keith; Kermany, Amir R; Myres, Natalie M; Barber, Mathew J; Rand, Kristin A; Song, Shiya; Roman, Theodore; Battat, Erin; Elyashiv, Eyal; Guturu, Harendra; Hong, Eurie L; Chahine, Kenneth G; Ball, Catherine A

2017-02-07

Despite strides in characterizing human history from genetic polymorphism data, progress in identifying genetic signatures of recent demography has been limited. Here we identify very recent fine-scale population structure in North America from a network of over 500 million genetic (identity-by-descent, IBD) connections among 770,000 genotyped individuals of US origin. We detect densely connected clusters within the network and annotate these clusters using a database of over 20 million genealogical records. Recent population patterns captured by IBD clustering include immigrants such as Scandinavians and French Canadians; groups with continental admixture such as Puerto Ricans; settlers such as the Amish and Appalachians who experienced geographic or cultural isolation; and broad historical trends, including reduced north-south gene flow. Our results yield a detailed historical portrait of North America after European settlement and support substantial genetic heterogeneity in the United States beyond that uncovered by previous studies.

Unexpected materials in a Rembrandt painting characterized by high spatial resolution cluster-TOF-SIMS imaging.

PubMed

Sanyova, Jana; Cersoy, Sophie; Richardin, Pascale; Laprévote, Olivier; Walter, Philippe; Brunelle, Alain

2011-02-01

The painting materials of the Portrait of Nicolaes van Bambeeck (Royal Museums of Fine Arts of Belgium, Brussels, inv. 155) painted by Rembrandt van Rijn in 1641 has been studied using high resolution cluster-TOF-SIMS imaging. In the first step, a moderate spatial resolution (2 μm) was used to characterize the layer structure and the chemical composition of each layer on account of a high mass resolution. Then, in the second step, and despite a low mass resolution, the cluster primary ion beam was focused well below 1 μm in order to reveal smaller structures in the painting sample. The study confirmed the presence of starch in the second ground layer, which is quite surprising and, at least for Rembrandt paintings, has never been reported before. TOF-SIMS also indicated the presence of proteins, which, added to the size and shape of lake particles, suggests that it was manufactured from shearings (waste of textile manufacturing) of dyed wool, used as the source of the dyestuff. The analyses have also shown various lead carboxylates, being the products of the interaction between lead white and the oil of the binding medium. These findings considerably contribute to the understanding of Rembrandt's studio practice and thus demonstrate the importance and potential of cluster-TOF-SIMS imaging in the characterization on a submicrometer scale of artist painting materials.

Identification of a t(3;4)(p1.3;q1.5) translocation breakpoint in pigs using somatic cell hybrid mapping and high-resolution mate-pair sequencing

PubMed Central

Fève, Katia; Foissac, Sylvain; Pinton, Alain; Mompart, Florence; Esquerré, Diane; Faraut, Thomas; Yerle, Martine

2017-01-01

Reciprocal translocations are the most frequently occurring constitutional structural rearrangements in mammalian genomes. In phenotypically normal pigs, an incidence of 1/200 is estimated for such rearrangements. Even if constitutional translocations do not necessarily induce defects and diseases, they are responsible for significant economic losses in domestic animals due to reproduction failures. Over the last 30 years, advances in molecular and cytogenetic technologies have led to major improvements in the resolution of the characterization of translocation events. Characterization of translocation breakpoints helps to decipher the mechanisms that lead to such rearrangements and the functions of the genes that are involved in the translocation. Here, we describe the fine characterization of a reciprocal translocation t(3;4) (p1.3;q1.5) detected in a pig line. The breakpoint was identified at the base-pair level using a positional cloning and chromosome walking strategy in somatic cell hybrids that were generated from an animal that carries this translocation. We show that this translocation occurs within the ADAMTSL4 gene and results in a loss of expression in homozygous carriers. In addition, by taking this translocation as a model, we used a whole-genome next-generation mate-pair sequencing approach on pooled individuals to evaluate this strategy for high-throughput screening of structural rearrangements. PMID:29121641

Synthesis, spectroscopic characterization, DFT optimization and biological activities of Schiff bases and their metal (II) complexes

NASA Astrophysics Data System (ADS)

Rauf, Abdur; Shah, Afzal; Munawar, Khurram Shahzad; Khan, Abdul Aziz; Abbasi, Rashda; Yameen, Muhammad Arfat; Khan, Asad Muhammad; Khan, Abdur Rahman; Qureshi, Irfan Zia; Kraatz, Heinz-Bernhard; Zia-ur-Rehman

2017-10-01

A Novel Schiff base, 3-(((4-chlorophenyl)imino)methyl)benzene-1,2-diol (HL1) was successfully synthesized along with a structurally similar Schiff base 3-(((4-bromophenyl)imino)methyl)benzene-1,2-diol (HL2). Both the Schiff bases were used to synthesize their zinc (II) and cobalt (II) complexes. These compounds were characterized by FTIR, 1H NMR, 13C NMR and elemental analysis. Metal complexes were confirmed by TGA. Crystals of Schiff bases were also characterized by X-ray analysis and experimental parameters were found in line with the theoretical parameters. Quantum mechanical approach was also used to fine useful structural parameters and to ensure the geometry of metal complexes. The photometric behaviors of all the synthesized compounds were investigated in a wide pH range using BR buffers. The appearance of isosbestic points indicated the existence of Schiff bases in more than one isomeric form. Moreover, these compounds were screened for enzyme inhibition; antibacterial, cytotoxic and in vivo antidiabetic activities and compounds were found active against one or other activity. Results indicate that ZnL22 is a good inhibitor of alkaline phosphatase enzyme and possess highest potential against diabetes, blood cholesterol level and cancer cells. This effort just provides preliminary data for some biological properties. Further investigations are required to precisely determine mechanistic pathways of their use towards drug development.

Structural and Lithologic Characterization of the SAFOD Pilot Hole and Phase One Main Hole

NASA Astrophysics Data System (ADS)

Barton, D. C.; Bradbury, K.; Solum, J. G.; Evans, J. P.

2005-12-01

Petrological and microstructural analyses of drill cuttings were conducted for the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole and Main Hole projects. Grain mounts were produced at ~30 m (100 ft) intervals from drill cuttings collected from the Pilot Hole to a depth of 2164 m (7100 ft) and from Phase 1 of the SAFOD main hole to a depth of 3067 m (10062 ft). . Thin-section grain mount analysis included identification of mineral composition, alteration, and deformation within individual grains, measured at .5 mm increments on an equally spaced, 300 point grid pattern. Lithologic features in the Quaternary/Tertiary deposits from 30 - 640 m (100-2100 ft) in the Pilot Hole, and 670 - 792 m (2200 - 2600 ft) in the Phase 1 main hole, include fine-grained, thinly bedded sediments with clasts of fine-grained volcanic groundmass. Preliminary grain mount analysis from 1920 - 3067 m (6300 - 10062) in the Phase 1 main hole, indicates a sedimentary sequence consisting of fine-grained lithic fragments of very fine-grained shale. Deformation mechanisms observed within the cuttings of granitic rocks from 914 - 1860 m (3000 - 6100 ft.) include intracrystalline plasticity and cataclasis. Intracrystalline plastic deformation within quartz and feldspar grains is indicated by undulatory extinction, ribbon grains, chessboard patterns, and deformation twins and lamellae. Cataclastic deformation is characterized by intra- and intergranular microfractures, angular grains, gouge zones, iron-oxide banding, and comminution. Mineral and cataclasite abundances were plotted as a function of weight percent vs. depth. Plots of quartz and feldspar abundances are also correlated with XRD weight percent data from 1160 - 1890 m (3800 - 6200 ft.) in the granitic and granodioritic sequences of the Phase 1 main hole. Regions of the both of the drill holes with cataclasite abundances ranging from 20 - 30 wt% are interpreted as shear zones. Shear zones identified in this study from 1150 - 1420 m (3773 - 4659 ft.) in the Pilot Hole occur in the same location as shear zones recognized by Boness and Zoback (2004) using borehole geophysical data. These shear zones may possibly be correlated to shear zones identified in the Phase I main hole from 1615 - 2012 m (5300 - 6600 ft). If this is the case, it can be explained by steeply dipping subsidiary fault zones, likely associated with the San Andreas Fault system.

High-resolution observations of active region moss and its dynamics

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

Morton, R. J.; McLaughlin, J. A., E-mail: richard.morton@northumbria.ac.uk

2014-07-10

The High Resolution Coronal Imager has provided the sharpest view of the EUV corona to date. In this paper, we exploit its impressive resolving power to provide the first analysis of the fine-scale structure of moss in an active region. The data reveal that the moss is made up of a collection of fine threads that have widths with a mean and standard deviation of 440 ± 190 km (FWHM). The brightest moss emission is located at the visible head of the fine-scale structure and the fine structure appears to extend into the lower solar atmosphere. The emission decreases alongmore » the features, implying that the lower sections are most likely dominated by cooler transition region plasma. These threads appear to be the cool, lower legs of the hot loops. In addition, the increased resolution allows for the first direct observation of physical displacements of the moss fine structure in a direction transverse to its central axis. Some of these transverse displacements demonstrate periodic behavior, which we interpret as a signature of kink (Alfvénic) waves. Measurements of the properties of the transverse motions are made and the wave motions have means and standard deviations of 55 ± 37 km for the transverse displacement amplitude, 77 ± 33 s for the period, and 4.7 ± 2.5 km s{sup –1} for the velocity amplitude. The presence of waves in the transition region of hot loops could have important implications for the heating of active regions.« less

Structural changes of starch during baking and staling of rye bread.

PubMed

Mihhalevski, Anna; Heinmaa, Ivo; Traksmaa, Rainer; Pehk, Tõnis; Mere, Arvo; Paalme, Toomas

2012-08-29

Rye sourdough breads go stale more slowly than wheat breads. To understand the peculiarities of bread staling, rye sourdough bread, wheat bread, and a number of starches were studied using wide-angle X-ray diffraction, nuclear magnetic resonance ((13)C CP MAS NMR, (1)H NMR, (31)P NMR), polarized light microscopy, rheological methods, microcalorimetry, and measurement of water activity. The degree of crystallinity of starch in breads decreased with hydration and baking to 3% and increased during 11 days of storage to 21% in rye sourdough bread and to 26% in wheat bread. (13)C NMR spectra show that the chemical structures of rye and wheat amylopectin and amylose contents are very similar; differences were found in the starch phospholipid fraction characterized by (31)P NMR. The (13)C CP MAS NMR spectra demonstrate that starch in rye sourdough breads crystallize in different forms than in wheat bread. It is proposed that different proportions of water incorporation into the crystalline structure of starch during staling and changes in starch fine structure cause the different rates of staling of rye and wheat bread.

Polyhedral Serpentine Grains in CM Chondrites

NASA Technical Reports Server (NTRS)

Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Stroud, Rhonda M.; Buseck, Peter R.

2005-01-01

CM chondrites are primitive rocks that experienced aqueous alteration in the early solar system. Their matrices and fine-grained rims (FGRs) sustained the effects of alteration, and the minerals within them hold clues to the aqueous reactions. Sheet silicates are an important product of alteration, and those of the serpentine group are abundant in the CM2 chondrites. Here we expand on our previous efforts to characterize the structure and chemistry of serpentines in CM chondrites and report results on a polyhedral form that is structurally similar to polygonal serpentine. Polygonal serpentine consists of tetrahedral (T) sheets joined to M(2+)-centered octahedral (O) sheets (where (M2+) is primarily Mg(2+) and Fe(2+)), which give rise to a 1:1 (TO) layered structure with a 0.7-nm layer periodicity. The structure is similar to chrysotile in that it consists of concentric lizardite layers wrapped around the fiber axis. However, unlike the rolled-up chrysotile, the tetrahedral sheets of the lizardite layers are periodically inverted and kinked, producing sectors. The relative angles between sectors result in 15- and 30-sided polygons in terrestrial samples.

Determination of local order in the amorphous precursor to Ba-hexaferrite thin-film recording media

NASA Astrophysics Data System (ADS)

Snyder, J. E.; Harris, V. G.; Das, B. N.; Koon, N. C.; Sui, X.; Kryder, M. H.

1996-04-01

Ba-hexaferrite thin films for recording media applications are often fabricated by a two-step process: sputter deposition of an amorphous precursor, followed by annealing to crystallize the BaFe12O19 phase. The magnetic anisotropy of the crystalline films can be either in-plane or perpendicular, depending on the sputtering process used in the first step. However, conventional structural characterization techniques have not been able to distinguish between different as-sputtered films. Using polarization-dependent extended x-ray absorption fine structure (PD-EXAFS), we have observed anisotropic local structure around both Ba and Fe atoms in the amorphous precursor films. Comparison of the results suggests that the amorphous films consist of networks of Fe atoms surrounded by their O nearest neighbors, with Ba atoms fitting into in-between spaces as network modifiers (there might also be some minor Fe network modifying contribution). The local structural anisotropy of the amorphous films appears to determine the orientation of the fast-growing basal plane directions during annealing, and thus the directions of the c axes and the magnetic anisotropy.

Chemical Bonding and Structural Information of Black CarbonReference Materials and Individual Carbonaceous AtmosphericAerosols

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

Hopkins, Rebecca J.; Tivanski, Alexei V.; Marten, Bryan D.

2007-04-25

The carbon-to-oxygen ratios and graphitic nature of a rangeof black carbon standard reference materials (BC SRMs), high molecularmass humic-like substances (HULIS) and atmospheric particles are examinedusing scanning transmission X-ray microscopy (STXM) coupled with nearedge X-ray absorption fine structure (NEXAFS) spectroscopy. UsingSTXM/NEXAFS, individual particles with diameter>100 nm are studied,thus the diversity of atmospheric particles collected during a variety offield missions is assessed. Applying a semi-quantitative peak fittingmethod to the NEXAFS spectra enables a comparison of BC SRMs and HULIS toparticles originating from anthropogenic combustion and biomass burns,thus allowing determination of the suitability of these materials forrepresenting atmospheric particles. Anthropogenic combustion andmore » biomassburn particles can be distinguished from one another using both chemicalbonding and structural ordering information. While anthropogeniccombustion particles are characterized by a high proportion ofaromatic-C, the presence of benzoquinone and are highly structurallyordered, biomass burn particles exhibit lower structural ordering, asmaller proportion of aromatic-C and contain a much higher proportion ofoxygenated functional groups.« less

Detection of fibrils associated with Rickettsia rickettsii.

PubMed

Todd, W J; Burgdorfer, W; Wray, G P

1983-09-01

The ultrastructural appearance of the "halozone" formed at the interface between the spotted fever agent Rickettsia rickettsii and the cytoplasm of persistently infected cultured vole cells (Microtus pennsylvanicus) was studied by transmission electron microscopy. In sections of epoxy-embedded specimens stained with uranyl acetate and lead citrate, the halozone appeared clear and devoid of ultrastructural features. However, when unembedded preparations of whole infected cells were examined at 1,000 kV, fine structural features were observed within the halozone. These features, associated with the rickettsial outer membrane, were more clearly detectable when the infected cells were extracted with the detergent Triton X-100 before fixation. Under such conditions, long extensions of the rickettsial outer membrane, microfilament-like structures attached to that membrane, and extensive attachments between adjacent rickettsiae were seen. The fine structural features within the rickettsial halozone were also seen at 75 kV when unembedded sections were prepared from polyethylene glycol-embedded specimens. Thus, epoxy-embedding medium obscures the fine structural features within the halozone surrounding the rickettsiae in infected cells.

Detection of fibrils associated with Rickettsia rickettsii.

PubMed Central

Todd, W J; Burgdorfer, W; Wray, G P

1983-01-01

The ultrastructural appearance of the "halozone" formed at the interface between the spotted fever agent Rickettsia rickettsii and the cytoplasm of persistently infected cultured vole cells (Microtus pennsylvanicus) was studied by transmission electron microscopy. In sections of epoxy-embedded specimens stained with uranyl acetate and lead citrate, the halozone appeared clear and devoid of ultrastructural features. However, when unembedded preparations of whole infected cells were examined at 1,000 kV, fine structural features were observed within the halozone. These features, associated with the rickettsial outer membrane, were more clearly detectable when the infected cells were extracted with the detergent Triton X-100 before fixation. Under such conditions, long extensions of the rickettsial outer membrane, microfilament-like structures attached to that membrane, and extensive attachments between adjacent rickettsiae were seen. The fine structural features within the rickettsial halozone were also seen at 75 kV when unembedded sections were prepared from polyethylene glycol-embedded specimens. Thus, epoxy-embedding medium obscures the fine structural features within the halozone surrounding the rickettsiae in infected cells. Images PMID:6411620

Julius Edgar Lilienfeld Prize Talk: Measuring the Electron Magnetic Moment and the Fine Structure Constant

NASA Astrophysics Data System (ADS)

Gabrielse, Gerald

2011-05-01

The electron magnetic moment in Bohr magnetons has been measured to a precision of 3 parts in 1013. This measurement, with quantum electrodynamics (AED) theory, provides the most precise value of the fine structure constant. This measurement, with a value of the fine structure from other measurements, also tests QED and sets a limit on the internal structure of the electron. A one-electron quantum cyclotron is at the heart of the measurement -- an electron suspended in a magnetic field and cooled enough that its lowest cyclotron and spin quantum states can be deduced with quantum nondemolition (QND) measurements. A cylindrical Penning trap cavity inhibits spontaneous emission and feedback methods make the electron excite and sustain its own motion for detection. A new apparatus is being commissioned in pursuit of more precise measurements. Adapted methods are promising for observing a proton spin flip, which should make it possible to compare the antiproton and proton magnetic moments a million times more accurately than is currently possible.

New determination of the fine structure constant from the electron value and QED.

PubMed

Gabrielse, G; Hanneke, D; Kinoshita, T; Nio, M; Odom, B

2006-07-21

Quantum electrodynamics (QED) predicts a relationship between the dimensionless magnetic moment of the electron (g) and the fine structure constant (alpha). A new measurement of g using a one-electron quantum cyclotron, together with a QED calculation involving 891 eighth-order Feynman diagrams, determine alpha(-1)=137.035 999 710 (96) [0.70 ppb]. The uncertainties are 10 times smaller than those of nearest rival methods that include atom-recoil measurements. Comparisons of measured and calculated g test QED most stringently, and set a limit on internal electron structure.

Large, high-intensity fire events in southern California shrublands: debunking the fine-grain age patch model.

PubMed

Keeley, Jon E; Zedler, Paul H

2009-01-01

We evaluate the fine-grain age patch model of fire regimes in southern California shrublands. Proponents contend that the historical condition was characterized by frequent small to moderate size, slow-moving smoldering fires, and that this regime has been disrupted by fire suppression activities that have caused unnatural fuel accumulation and anomalously large and catastrophic wildfires. A review of more than 100 19th-century newspaper reports reveals that large, high-intensity wildfires predate modern fire suppression policy, and extensive newspaper coverage plus first-hand accounts support the conclusion that the 1889 Santiago Canyon Fire was the largest fire in California history. Proponents of the fine-grain age patch model contend that even the very earliest 20th-century fires were the result of fire suppression disrupting natural fuel structure. We tested that hypothesis and found that, within the fire perimeters of two of the largest early fire events in 1919 and 1932, prior fire suppression activities were insufficient to have altered the natural fuel structure. Over the last 130 years there has been no significant change in the incidence of large fires greater than 10,000 ha, consistent with the conclusion that fire suppression activities are not the cause of these fire events. Eight megafires (> or = 50,000 ha) are recorded for the region, and half have occurred in the last five years. These burned through a mosaic of age classes, which raises doubts that accumulation of old age classes explains these events. Extreme drought is a plausible explanation for this recent rash of such events, and it is hypothesized that these are due to droughts that led to increased dead fine fuels that promoted the incidence of firebrands and spot fires. A major shortcoming of the fine-grain age patch model is that it requires age-dependent flammability of shrubland fuels, but seral stage chaparral is dominated by short-lived species that create a dense surface layer of fine fuels. Results from the Behave Plus fire model with a custom fuel module for young chaparral shows that there is sufficient dead fuel to spread fire even under relatively little winds. Empirical studies of fuel ages burned in recent fires illustrate that young fuels often comprise a major portion of burned vegetation, and there is no difference between evergreen chaparral and semi-deciduous sage scrub. It has also been argued that the present-day fire size distribution in northern Baja California is a model of the historical patterns that were present on southern California landscapes. Applying this model with historical fire frequencies shows that the Baja model is inadequate to maintain these fire-prone ecosystems and further demonstrates that fire managers in southern California are not likely to learn much from studying modern Baja California fire regimes. Further supporting this conclusion are theoretical cellular automata models of fire spread, which show that, even in systems with age dependent flammability, landscapes evolve toward a complex age mosaic with a plausible age structure only when there is a severe stopping rule that constrains fire size, and only if ignitions are saturating.

Large, high-intensity fire events in Southern California shrublands: Debunking the fine-grain age patch model

USGS Publications Warehouse

Keeley, J.E.; Zedler, P.H.

2009-01-01

We evaluate the fine-grain age patch model of fire regimes in southern California shrublands. Proponents contend that the historical condition was characterized by frequent small to moderate size, slow-moving smoldering fires, and that this regime has been disrupted by fire suppression activities that have caused unnatural fuel accumulation and anomalously large and catastrophic wildfires. A review of more than 100 19th-century newspaper reports reveals that large, high-intensity wildfires predate modern fire suppression policy, and extensive newspaper coverage plus first-hand accounts support the conclusion that the 1889 Santiago Canyon Fire was the largest fire in California history. Proponents of the fine-grain age patch model contend that even the very earliest 20th-century fires were the result of fire suppression disrupting natural fuel structure. We tested that hypothesis and found that, within the fire perimeters of two of the largest early fire events in 1919 and 1932, prior fire suppression activities were insufficient to have altered the natural fuel structure. Over the last 130 years there has been no significant change in the incidence of large fires greater than 10000 ha, consistent with the conclusion that fire suppression activities are not the cause of these fire events. Eight megafires (???50 000 ha) are recorded for the region, and half have occurred in the last five years. These burned through a mosaic of age classes, which raises doubts that accumulation of old age classes explains these events. Extreme drought is a plausible explanation for this recent rash of such events, and it is hypothesized that these are due to droughts that led to increased dead fine fuels that promoted the incidence of firebrands and spot fires. A major shortcoming of the fine-grain age patch model is that it requires age-dependent flammability of shrubland fuels, but seral stage chaparral is dominated by short-lived species that create a dense surface layer of fine fuels. Results from the Behave Plus fire model with a custom fuel module for young chaparral shows that there is sufficient dead fuel to spread fire even under relatively little winds. Empirical studies of fuel ages burned in recent fires illustrate that young fuels often comprise a major portion of burned vegetation, and there is no difference between evergreen chaparral and semi-deciduous sage scrub. It has also been argued that the present-day fire size distribution in northern Baja California is a model of the historical patterns that were present on southern California landscapes. Applying this model with historical fire frequencies shows that the Baja model is inadequate to maintain these fire-prone ecosystems and further demonstrates that fire managers in southern California are not likely to learn much from studying modern Baja California fire regimes. Further supporting this conclusion are theoretical cellular automata models of fire spread, which show that, even in systems with age dependent flammability, landscapes evolve toward a complex age mosaic with a plausible age structure only when there is a severe stopping rule that constrains fire size, and only if ignitions are saturating. ?? 2009 by the Ecological Society of America.

Image Texture Predicts Avian Density and Species Richness

PubMed Central

Wood, Eric M.; Pidgeon, Anna M.; Radeloff, Volker C.; Keuler, Nicholas S.

2013-01-01

For decades, ecologists have measured habitat attributes in the field to understand and predict patterns of animal distribution and abundance. However, the scale of inference possible from field measured data is typically limited because large-scale data collection is rarely feasible. This is problematic given that conservation and management typical require data that are fine grained yet broad in extent. Recent advances in remote sensing methodology offer alternative tools for efficiently characterizing wildlife habitat across broad areas. We explored the use of remotely sensed image texture, which is a surrogate for vegetation structure, calculated from both an air photo and from a Landsat TM satellite image, compared with field-measured vegetation structure, characterized by foliage-height diversity and horizontal vegetation structure, to predict avian density and species richness within grassland, savanna, and woodland habitats at Fort McCoy Military Installation, Wisconsin, USA. Image texture calculated from the air photo best predicted density of a grassland associated species, grasshopper sparrow (Ammodramus savannarum), within grassland habitat (R2 = 0.52, p-value <0.001), and avian species richness among habitats (R2 = 0.54, p-value <0.001). Density of field sparrow (Spizella pusilla), a savanna associated species, was not particularly well captured by either field-measured or remotely sensed vegetation structure variables, but was best predicted by air photo image texture (R2 = 0.13, p-value = 0.002). Density of ovenbird (Seiurus aurocapillus), a woodland associated species, was best predicted by pixel-level satellite data (mean NDVI, R2 = 0.54, p-value <0.001). Surprisingly and interestingly, remotely sensed vegetation structure measures (i.e., image texture) were often better predictors of avian density and species richness than field-measured vegetation structure, and thus show promise as a valuable tool for mapping habitat quality and characterizing biodiversity across broad areas. PMID:23675463

The influence of clay fineness upon sludge recycling in a ceramic matrix

NASA Astrophysics Data System (ADS)

Szőke, A. M.; Muntean, M.; Sándor, M.; Brotea, L.

2016-04-01

The feasibility of sludge recycling in the ceramic manufacture was evaluated through laboratory testing. Such residues have similar chemical and mineralogical composition with the raw mixture of the green ceramic body used in construction. Several ceramic masses with clay and various proportion of sludge have been synthesized and then characterized by their physical-mechanical properties. The fineness of the clay, the main component of the green ceramic body, has been considered for every raw mixture. The proportion of the sludge waste addition depends on the clay fineness and the sintering capacity also, increases with the clay fineness. The ceramic properties, particularly, the open porosity, and mechanical properties, in presence of small sludge proportion (7, 20%) shows small modification. The introduction of such waste into building ceramic matrix (bricks, tiles, and plates) has a very good perspective.

Identification of magnetic minerals in the fine-grain sediment on the Bengawan Solo River

NASA Astrophysics Data System (ADS)

Purnama, B.; Kusuma, R.; Legowo, B.; Suharyana; Wijayanta, A. T.

2018-03-01

The magnetic mineral content in the fine sediment of Bengawan Solo River is discussed. The fine sediment is obtained on the upper part of the tributary of Bengawan Solo River. Magnetic minerals are separated using permanent magnets. Furthermore the magnetic minerals are overnight dried using oven at 100°C. FTIR characterization indicate that the magnetic minerals in the fine sediment of Bengawan Solo River have the same characteristics as minerals in Cilacap and Purwokerto areas. Magnetic minerals are estimated to form at wave number k = 569.03 cm-1. This hematite content increase to 70.67% after anealling treatment at 600°C for 4 hours in atmosphere condition. This result is interesting because the heating process increases the hematite content. Within results, the magnetic properties of the sample will change.

Structural and electrical properties of In-implanted Ge

DOE PAGES

Feng, R.; Kremer, F.; Sprouster, D. J.; ...

2015-10-22

Here, we report on the effects of dopant concentration on the structural and electrical properties of In-implanted Ge. For In concentrations of ≤ 0.2 at. %, extended x-ray absorption fine structure and x-ray absorption near-edge structure measurements demonstrate that all In atoms occupy a substitutional lattice site while metallic In precipitates are apparent in transmission electron micrographs for In concentrations ≥0.6 at. %. Evidence of the formation of In-vacancy complexes deduced from extended x-ray absorption fine structure measurements is complimented by density functional theory simulations. Hall effect measurements of the conductivity, carrier density, and carrier mobility are then correlated withmore » the substitutional In fraction.« less

Riedel thyroiditis: Fine needle aspiration findings of a rare entity.

PubMed

Weidner, Anna-Sophie; Molina, David; DeSimone, Robert A; Cohen, Marc A; Giorgadze, Tamar; Scognamiglio, Theresa; Hoda, Rana S

2015-09-01

Riedel thyroiditis is a rare fibrosing disorder characterized by extension of the fibroinflammatory process beyond the thyroid capsule. Due to the nature of this lesion, fine-needle aspiration often yields scant material and may be interpreted as non-diagnostic. In this report, we describe cytologic features that allow the cytopathologist to favor a diagnosis of Riedel thyroiditis, thereby guiding appropriate further work-up and management. © 2015 Wiley Periodicals, Inc.

Structural and facies characterization of the Niobrara Formation in Goshen and Laramie counties, Wyoming

NASA Astrophysics Data System (ADS)

Kernan, Nicholas Devereux

The Niobrara Formation is a fine-grained marine rock deposited in the Western Interior Seaway during the Late Cretaceous. It is composed of fossil-rich interlayered shale, marls, and chalks. Recent interest in the Niobrara has grown due to the advent of lateral drilling and multi-stage hydraulic fracturing. This technology allows operators to economically extract hydrocarbons from chalkier Niobrara facies. Yet two aspects of the Niobrara Formation have remained enigmatic. The first is the occurrence of abundant, randomly oriented, layer-bound, normal faults. The second is the large degree of vertical heterogeneity. This research aimed to increase understanding in both these aspects of the Niobrara Formation. Randomly oriented normal faults have been observed in Niobrara outcrops for nearly a hundred years. Recent high resolution 3D seismic in the Denver Basin has allowed investigators to interpret these faults as part of a polygonal fault system (PFS). PFS are layer bound extensional structures that typically occur in fine-grained marine sediments. Though their genesis and development is still poorly understood, their almost exclusive occurrence in fine-grained rocks indicates their origin is linked to lithology. Interpretation of a 3D seismic cube in Southeast Wyoming found a tier of polygonal faulting within the Greenhorn-Carlile formations and another tier of polygonal faulting within the Niobrara and Pierre formations. This research also found that underlying structural highs influence fault growth and geometries within both these tiers. Core data and thin sections best describe vertical heterogeneity in fine-grained rocks. This investigation interpreted core data and thin sections in a well in Southeast Wyoming and identified 10 different facies. Most of these facies fall within a carbonate/clay spectrum with clay-rich facies deposited during periods of lower sea level and carbonate-rich facies deposited during periods of higher sea level. Because the average operator will typically have little core but abundant well logs, this investigation used three different methods of describing facies variability with logs. Facies interpreted with these methods are referred to as electrofacies. First, a conventional interpretation of Niobrara sub-units was done using gamma ray and resistivity logs. Then a cluster analysis was conducted on an extensive petrophysical log suite. Finally, a neural network was trained with the previous core interpretation so that it learned to identify facies from logs. The research found that when little core is available a cluster analysis method can capture significant amounts of vertical heterogeneity within the Niobrara Formation. But if core is available then a neural network method provides more meaningful and higher resolution interpretations.

Rocket observations of electron-density irregularities in the equatorial ionosphere below 200 km

NASA Technical Reports Server (NTRS)

Klaus, D. E.; Smith, L. G.

1978-01-01

Nike Apache rockets carring instrumentation to measure electron density and its fine structure in the equatorial ionosphere were launched from Chilca, Peru in May and June 1975. The fine structure experiment and the data reduction system are described. Results obtained from this system are presented and compared with those obtained by VHF radar and from other rocket studies. A description of the equatorial ionosphere and its features is also presented.

Effective collision strengths for the electron impact excitation of Mg

NASA Astrophysics Data System (ADS)

Hudson, C. E.; Ramsbottom, C. A.; Norrington, P. H.; Scott, M. P.

2008-05-01

Electron impact excitation collision strengths for fine structure transitions of Mg,have been determined by a Breit-Pauli R-matrix calculation. The target states are represented by configuration interaction wavefunctions and consist of the 19 lowest LS states, having configurations 2s^22p^4, 2s2p^5, 2p^6, 2s^22p^33s and 2s^22p^33p. These target states give rise to 37 fine structure levels and 666 possible transitions. The effective collision strengths are calculated by averaging the electron collision strengths over a Maxwellian distribution of electron velocities. Effective collision strengths for transitions between the fine structure levels are given for electron temperatures in the range 10Te(K) = 3.0 - 7.0. Results are compared with the previous R-matrix calculation of Butler & Zeippen (AASS, 1994) and the recent Distorted Wave evaluations of Bhatia, Landi & Eissner (ADNDT, 2006).

Annealing induced atomic rearrangements on (Ga,In) (N,As) probed by hard X-ray photoelectron spectroscopy and X-ray absorption fine structure.

PubMed

Ishikawa, Fumitaro; Higashi, Kotaro; Fuyuno, Satoshi; Morifuji, Masato; Kondow, Masahiko; Trampert, Achim

2018-04-13

We study the effects of annealing on (Ga 0.64 ,In 0.36 ) (N 0.045 ,As 0.955 ) using hard X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements. We observed surface oxidation and termination of the N-As bond defects caused by the annealing process. Specifically, we observed a characteristic chemical shift towards lower binding energies in the photoelectron spectra related to In. This phenomenon appears to be caused by the atomic arrangement, which produces increased In-N bond configurations within the matrix, as indicated by the X-ray absorption fine structure measurements. The reduction in the binding energies of group-III In, which occurs concomitantly with the atomic rearrangements of the matrix, causes the differences in the electronic properties of the system before and after annealing.

Dynamic Jahn-Teller effect: Calculation of fine structure spectrum, isotope shift and Zeeman behavior at deep center Ni2+ in CdS

NASA Astrophysics Data System (ADS)

Schoepp, Juergen

The internal transition of the deep center Ni2+ in II to IV semiconductor cadmium sulfide is examined with reference to crystal field theory. An algorithm was developed for calculation, in a basis fitted to trigonal symmetry, of fine structure operator matrix which is made of the sum of operators from spin trajectory coupling, trigonal field and electron phonon coupling. The dependence of energy level on the mass was calculated in order to examine the isotropy effect at Ni2+ transition. The mass dependence of phonon energy was estimated in an atomic cluster by using a valence force model from Keating for elastic energy. The Zeeman behavior of Ni2+ transition was examined for magnetic fields; the Zeeman operator was added to the fine structure operator and the resulting matrix was diagonalized. It is noticed that calculations are quantitatively and qualitatively in agreement with experiments.

Fine structure constant and quantized optical transparency of plasmonic nanoarrays.

PubMed

Kravets, V G; Schedin, F; Grigorenko, A N

2012-01-24

Optics is renowned for displaying quantum phenomena. Indeed, studies of emission and absorption lines, the photoelectric effect and blackbody radiation helped to build the foundations of quantum mechanics. Nevertheless, it came as a surprise that the visible transparency of suspended graphene is determined solely by the fine structure constant, as this kind of universality had been previously reserved only for quantized resistance and flux quanta in superconductors. Here we describe a plasmonic system in which relative optical transparency is determined solely by the fine structure constant. The system consists of a regular array of gold nanoparticles fabricated on a thin metallic sublayer. We show that its relative transparency can be quantized in the near-infrared, which we attribute to the quantized contact resistance between the nanoparticles and the metallic sublayer. Our results open new possibilities in the exploration of universal dynamic conductance in plasmonic nanooptics.

Fine Structure of Beta Decay Strength Function and Anisotropy of Isovector Nuclear Dencity Component Oscillations in Deformed Nuclei

NASA Astrophysics Data System (ADS)

Izosimov, I. N.; Solnyshkin, A. A.; Khushvaktov, J. H.; Vaganov, Yu. A.

2018-05-01

The experimental measurement data on the fine structure of beta-decay strength function S β( E) in spherical, transitional, and deformed nuclei are analyzed. Modern high-resolution nuclear spectroscopy methods made it possible to identify the splitting of peaks in S β( E) for deformed nuclei. By analogy with splitting of the peak of E1 giant dipole resonance (GDR) in deformed nuclei, the peaks in S β( E) are split into two components from the axial nuclear deformation. In this report, the fine structure of S β( E) is discussed. Splitting of the peaks connected with the oscillations of neutrons against protons (E1GDR), of proton holes against neutrons (peaks in S β( E) of β+/ EC-decay), and of protons against neutron holes (peaks in S β( E) of β--decay) is discussed.

Band-Edge Exciton Fine Structure and Recombination Dynamics in InP/ZnS Colloidal Nanocrystals.

PubMed

Biadala, Louis; Siebers, Benjamin; Beyazit, Yasin; Tessier, Mickaël D; Dupont, Dorian; Hens, Zeger; Yakovlev, Dmitri R; Bayer, Manfred

2016-03-22

We report on a temperature-, time-, and spectrally resolved study of the photoluminescence of type-I InP/ZnS colloidal nanocrystals with varying core size. By studying the exciton recombination dynamics we assess the exciton fine structure in these systems. In addition to the typical bright-dark doublet, the photoluminescence stems from an upper bright state in spite of its large energy splitting (∼100 meV). This striking observation results from dramatically lengthened thermalization processes among the fine structure levels and points to optical-phonon bottleneck effects in InP/ZnS nanocrystals. Furthermore, our data show that the radiative recombination of the dark exciton scales linearly with the bright-dark energy splitting for CdSe and InP nanocrystals. This finding strongly suggests a universal dangling bonds-assisted recombination of the dark exciton in colloidal nanostructures.

Reconstruction of vessel structures from serial whole slide sections of murine liver samples

NASA Astrophysics Data System (ADS)

Schwier, Michael; Hahn, Horst K.; Dahmen, Uta; Dirsch, Olaf

2013-03-01

Image-based analysis of the vascular structures of murine liver samples is an important tool for scientists to understand liver physiology and morphology. Typical assessment methods are MicroCT, which allows for acquiring images of the whole organ while lacking resolution for fine details, and confocal laser scanning microscopy, which allows detailed insights into fine structures while lacking the broader context. Imaging of histological serial whole slide sections is a recent technology able to fill this gap, since it provides a fine resolution up to the cellular level, but on a whole organ scale. However, whole slide imaging is a modality providing only 2D images. Therefore the challenge is to use stacks of serial sections from which to reconstruct the 3D vessel structures. In this paper we present a semi-automatic procedure to achieve this goal. We employ an automatic method that detects vessel structures based on continuity and shape characteristics. Furthermore it supports the user to perform manual corrections where required. With our methods we were able to successfully extract and reconstruct vessel structures from a stack of 100 and a stack of 397 serial sections of a mouse liver lobe, thus proving the potential of our approach.

Fine-scale genetic structure in populations of the Chagas' disease vector Triatoma infestans (Hemiptera, Reduvidae).

PubMed

Pérez de Rosas, Alicia R; Segura, Elsa L; Fusco, Octavio; Guiñazú, Adolfo L Bareiro; García, Beatriz A

2013-03-01

Fine scale patterns of genetic structure and dispersal in Triatoma infestans populations from Argentina was analysed. A total of 314 insects from 22 domestic and peridomestic sites from the locality of San Martín (Capayán department, Catamarca province) were typed for 10 polymorphic microsatellite loci. The results confirm subdivision of T. infestans populations with restricted dispersal among sampling sites and suggest inbreeding and/or stratification within the different domestic and peridomestic structures. Spatial correlation analysis showed that the scale of structuring is approximately of 400 m, indicating that active dispersal would occur within this distance range. It was detected difference in scale of structuring among sexes, with females dispersing over greater distances than males. This study suggests that insecticide treatment and surveillance should be extended within a radius of 400 m around the infested area, which would help to reduce the probability of reinfestation by covering an area of active dispersal. The inferences made from fine-scale spatial genetic structure analyses of T. infestans populations has demonstrated to be important for community-wide control programs, providing a complementary approach to help improve vector control strategies.

Systematic oxidation of polystyrene by ultraviolet-ozone, characterized by near-edge X-ray absorption fine structure and contact angle.

PubMed

Klein, Robert J; Fischer, Daniel A; Lenhart, Joseph L

2008-08-05

The process of implanting oxygen in polystyrene (PS) via exposure to ultraviolet-ozone (UV-O) was systematically investigated using the characterization technique of near-edge X-ray absorption fine structure (NEXAFS). Samples of PS exposed to UV-O for 10-300 s and washed with isopropanol were analyzed using the carbon and oxygen K-edge NEXAFS partial electron yields, using various retarding bias voltages to depth-profile the oxygen penetration into the surface. Evaluation of reference polymers provided a scale to quantify the oxygen concentration implanted by UV-O treatment. We find that ozone initially reacts with the double bonds on the phenyl rings, forming carbonyl groups, but within 1 min of exposure, the ratio of double to single oxygen bonds stabilizes at a lower value. Oxygen penetrates the film with relative ease, creating a fairly uniform distribution of oxygen within at least the first 4 nm (the effective depth probed by NEXAFS here). Before oxygen accumulates in large concentrations, however, it preferentially degrades the uppermost layer of the film by removing oxygenated low-molecular-weight oligomers. The failure to accumulate high concentrations of oxygen is seen in the nearly constant carbon edge jump, the low concentration of oxygen even at 5 min exposure (58% of that in poly(4-acetoxystyrene), the polymer with the most similarities to UV-O-treated PS), and the relatively high contact angles. At 5 min exposure the oxygen concentration contains ca. 7 atomic % oxygen. The oxygen species that are implanted consist predominantly of single O-C bonds and double O=C bonds but also include a small fraction of O-H. UV-O treatment leads a plateau after 2 min exposure in the water contact angle hysteresis, at a value of 67 +/- 2 degrees , due primarily to chemical heterogeneity. Annealing above T(g) allows oxygenated species to move short distances away from the surface but not diffuse further than 1-2 nm.

Neuronal Ensemble Synchrony during Human Focal Seizures

PubMed Central

Ahmed, Omar J.; Harrison, Matthew T.; Eskandar, Emad N.; Cosgrove, G. Rees; Madsen, Joseph R.; Blum, Andrew S.; Potter, N. Stevenson; Hochberg, Leigh R.; Cash, Sydney S.

2014-01-01

Seizures are classically characterized as the expression of hypersynchronous neural activity, yet the true degree of synchrony in neuronal spiking (action potentials) during human seizures remains a fundamental question. We quantified the temporal precision of spike synchrony in ensembles of neocortical neurons during seizures in people with pharmacologically intractable epilepsy. Two seizure types were analyzed: those characterized by sustained gamma (∼40–60 Hz) local field potential (LFP) oscillations or by spike-wave complexes (SWCs; ∼3 Hz). Fine (<10 ms) temporal synchrony was rarely present during gamma-band seizures, where neuronal spiking remained highly irregular and asynchronous. In SWC seizures, phase locking of neuronal spiking to the SWC spike phase induced synchrony at a coarse 50–100 ms level. In addition, transient fine synchrony occurred primarily during the initial ∼20 ms period of the SWC spike phase and varied across subjects and seizures. Sporadic coherence events between neuronal population spike counts and LFPs were observed during SWC seizures in high (∼80 Hz) gamma-band and during high-frequency oscillations (∼130 Hz). Maximum entropy models of the joint neuronal spiking probability, constrained only on single neurons' nonstationary coarse spiking rates and local network activation, explained most of the fine synchrony in both seizure types. Our findings indicate that fine neuronal ensemble synchrony occurs mostly during SWC, not gamma-band, seizures, and primarily during the initial phase of SWC spikes. Furthermore, these fine synchrony events result mostly from transient increases in overall neuronal network spiking rates, rather than changes in precise spiking correlations between specific pairs of neurons. PMID:25057195

Local structural and chemical ordering of nanosized Pt3±δCo probed by multiple-scattering x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Greco, Giorgia; Witkowska, Agnieszka; Principi, Emiliano; Minicucci, Marco; di Cicco, Andrea

2011-04-01

This work reports a detailed investigation of the local structure and chemical disorder of a Pt3±δCo thin film and Pt3±δCo nanoparticles. We have used a combination of techniques including x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and high-resolution transmission electron microscopy (TEM). High-quality XAS spectra at the Co K edge and Pt L3 edge have been analyzed using double-edge multiple-scattering data analysis. Structural extended x-ray absorption fine structure (EXAFS) refinements have been performed accounting for the reduction of the coordination numbers and degeneracy of three-atom configurations, resulting from the measured size distribution and stoichiometry. The important effect of chemical ordering on pair and three-atom configurations has been studied using computer simulations based on a simple model accounting for substitutional disorder, defined by an order parameter s. It has been found that individual EXAFS signals related to the minority species (Co) are extremely sensitive to substitutional disorder so their intensities, especially those of the collinear three-atom configurations, can be used as a measure of the ordering level. The thin film has been found to be chemically disordered (s⩽0.4), in agreement with previous estimates. The Pt3±δCo nanoalloy has been found to be partially ordered (s=0.6±0.1) while the local structure around Co atoms is characterized by a higher level of structural disorder as compared to the bulk-like thin film. The robust approach for nanomaterial characterization used in this work combining different techniques can, in principle, be applied for structural refinements of any binary nanocrystalline functional system.

Correlative multi-scale characterization of a fine grained Nd-Fe-B sintered magnet.

PubMed

Sasaki, T T; Ohkubo, T; Hono, K; Une, Y; Sagawa, M

2013-09-01

The Nd-rich phases in pressless processed fine grained Nd-Fe-B sintered magnets have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and three dimensional atom probe tomography (3DAP). The combination of the backscattered electron (BSE) and in-lens secondary electron (IL-SE) images in SEM led to an unambiguous identification of four types of Nd-rich phases, NdOx, Ia3 type phase, which is isostructural to Nd₂O₃, dhcp-Nd and Nd₁Fe₄B₄. In addition, the 3DAP analysis of thin Nd-rich grain boundary layer indicate that the coercivity has a close correlation with the chemistry of the grain boundary phase. Copyright © 2013 Elsevier B.V. All rights reserved.

Coupling physics and biogeochemistry thanks to high-resolution observations of the phytoplankton community structure in the northwestern Mediterranean Sea

NASA Astrophysics Data System (ADS)

Marrec, Pierre; Grégori, Gérald; Doglioli, Andrea M.; Dugenne, Mathilde; Della Penna, Alice; Bhairy, Nagib; Cariou, Thierry; Hélias Nunige, Sandra; Lahbib, Soumaya; Rougier, Gilles; Wagener, Thibaut; Thyssen, Melilotus

2018-03-01

Fine-scale physical structures and ocean dynamics strongly influence and regulate biogeochemical and ecological processes. These processes are particularly challenging to describe and understand because of their ephemeral nature. The OSCAHR (Observing Submesoscale Coupling At High Resolution) campaign was conducted in fall 2015 in which a fine-scale structure (1-10 km/1-10 days) in the northwestern Mediterranean Ligurian subbasin was pre-identified using both satellite and numerical modeling data. Along the ship track, various variables were measured at the surface (temperature, salinity, chlorophyll a and nutrient concentrations) with ADCP current velocity. We also deployed a new model of the CytoSense automated flow cytometer (AFCM) optimized for small and dim cells, for near real-time characterization of the surface phytoplankton community structure of surface waters with a spatial resolution of a few kilometers and an hourly temporal resolution. For the first time with this optimized version of the AFCM, we were able to fully resolve Prochlorococcus picocyanobacteria in addition to the easily distinguishable Synechococcus. The vertical physical dynamics and biogeochemical properties of the studied area were investigated by continuous high-resolution CTD profiles thanks to a moving vessel profiler (MVP) during the vessel underway associated with a high-resolution pumping system deployed during fixed stations allowing sampling of the water column at a fine resolution (below 1 m). The observed fine-scale feature presented a cyclonic structure with a relatively cold core surrounded by warmer waters. Surface waters were totally depleted in nitrate and phosphate. In addition to the doming of the isopycnals by the cyclonic circulation, an intense wind event induced Ekman pumping. The upwelled subsurface cold nutrient-rich water fertilized surface waters and was marked by an increase in Chl a concentration. Prochlorococcus and pico- and nano-eukaryotes were more abundant in cold core waters, while Synechococcus dominated in warm boundary waters. Nanoeukaryotes were the main contributors ( > 50 %) in terms of pigment content (red fluorescence) and biomass. Biological observations based on the mean cell's red fluorescence recorded by AFCM combined with physical properties of surface waters suggest a distinct origin for two warm boundary waters. Finally, the application of a matrix growth population model based on high-frequency AFCM measurements in warm boundary surface waters provides estimates of in situ growth rate and apparent net primary production for Prochlorococcus (μ = 0.21 d-1, NPP = 0.11 mg C m-3 d-1) and Synechococcus (μ = 0.72 d-1, NPP = 2.68 mg C m-3 d-1), which corroborate their opposite surface distribution pattern. The innovative adaptive strategy applied during OSCAHR with a combination of several multidisciplinary and complementary approaches involving high-resolution in situ observations and sampling, remote-sensing and model simulations provided a deeper understanding of the marine biogeochemical dynamics through the first trophic levels.

Lithosphere structure of the west Qinling orogenic belt revealed by deep seismic reflection profile

NASA Astrophysics Data System (ADS)

Wang, H.

2009-12-01

The west Qinling orogen located in the northeastern margin of the Qinghai-Tibet plateau, is transformation zone between the N-S-trending and E-W-trending tectonics in the Chinese continent. Further study of the fine crust structure of the west Qinling orogen and its relationships with surrounding basins have very important significance for understanding tectonic response of the northeastern margin of the plateau about collision convergence of the Indian block and Asian block and learning formation and evolution of the plateau. In 2009, we reprocessed the data of the Tangke-Hezuo deep seismic reflection profiles collected in 2004 across the west Qinling orogen and the northern Songpan block. The new results show the lithosphere fine structure of the west Qinling orogen. Reflection features indicate that an interface at 6.0-7.0s (TWT) divided the crust into the upper and lower crust, whose structural style and deformation are totally different. Integrating geological data, we deduce that the interface at 6.0-7.0s (depth with 18-21 km) was the basement detachment, which made deformation decoupled of the upper and lower crust. The multi-layered reflections in the upper crust reveal the sedimentary covers of the west Qinling orogen, disclose the thickness of the various structure layer and deformation degree, and provide a basis for the prospective evaluation of a multi-metallic mineral and energy exploration. The north dipping strong reflection characteristics of the lower crust in the west Qinling orogen constituted imbricate structure, such imbricate structural features provide seismology evidence for researching the west Qinling thrusting toward the northern Songpan block, and have great significance for studying formation and evolution of the Songpan-Garze structure. Moho reflections are observed around 17.0-17.2s, characterized by nearly horizontal reflections, which implies the west Qinling orogen underwent an intense extension post orogeny caused the lithosphere extensional thinning formed a nearly level Moho reflections. The study was financed by National Natural Science Foundation of china (No. 40830316 and 40604010),the Basic outlay of scientific research work from Ministry of Science and Technology of the People’s Republic of China and SINOPPROBE-02.

Structural control of ultra-fine CoPt nanodot arrays via electrodeposition process

NASA Astrophysics Data System (ADS)

Wodarz, Siggi; Hasegawa, Takashi; Ishio, Shunji; Homma, Takayuki

2017-05-01

CoPt nanodot arrays were fabricated by combining electrodeposition and electron beam lithography (EBL) for the use of bit-patterned media (BPM). To achieve precise control of deposition uniformity and coercivity of the CoPt nanodot arrays, their crystal structure and magnetic properties were controlled by controlling the diffusion state of metal ions from the initial deposition stage with the application of bath agitation. Following bath agitation, the composition gradient of the CoPt alloy with thickness was mitigated to have a near-ideal alloy composition of Co:Pt =80:20, which induces epitaxial-like growth from Ru substrate, thus resulting in the improvement of the crystal orientation of the hcp (002) structure from its initial deposition stages. Furthermore, the cross-sectional transmission electron microscope (TEM) analysis of the nanodots deposited with bath agitation showed CoPt growth along its c-axis oriented in the perpendicular direction, having uniform lattice fringes on the hcp (002) plane from the Ru underlayer interface, which is a significant factor to induce perpendicular magnetic anisotropy. Magnetic characterization of the CoPt nanodot arrays showed increase in the perpendicular coercivity and squareness of the hysteresis loops from 2.0 kOe and 0.64 (without agitation) to 4.0 kOe and 0.87 with bath agitation. Based on the detailed characterization of nanodot arrays, the precise crystal structure control of the nanodot arrays with ultra-high recording density by electrochemical process was successfully demonstrated.

Canopy rainfall partitioning across an urbanization gradient in forest structure as characterized by terrestrial LiDAR

NASA Astrophysics Data System (ADS)

Mesta, D. C.; Van Stan, J. T., II; Yankine, S. A.; Cote, J. F.; Jarvis, M. T.; Hildebrandt, A.; Friesen, J.; Maldonado, G.

2017-12-01

As urbanization expands, greater forest area is shifting from natural stand structures to urban stand structures, like forest fragments and landscaped tree rows. Changes in forest canopy structure have been found to drastically alter the amount of rainwater reaching the surface. However, stormwater management models generally treat all forest structures (beyond needle versus broadleaved) similarly. This study examines the rainfall partitioning of Pinus spp. canopies along a natural-to-urban forest gradient and compares these to canopy structural measurements using terrestrial LiDAR. Throughfall and meteorological observations were also used to estimate parameters of the commonly-used Gash interception model. Preliminary findings indicate that as forest structure changed from natural, closed canopy conditions to semi-closed canopy fragments and, ultimately, to exposed urban landscaping tree rows, the interchange between throughfall and rainfall interception also changed. This shift in partitioning between throughfall and rainfall interception may be linked to intuitive parameters, like canopy closure and density, as well as more complex metrics, like the fine-scale patterning of gaps (ie, lacunarity). Thus, results indicate that not all forests of the same species should be treated the same by stormwater models. Rather, their canopy structural characteristics should be used to vary their hydrometeorological interactions.

Structure and magnetism in Co/X, Fe/Si, and Fe/(FeSi) multilayers

NASA Astrophysics Data System (ADS)

Franklin, Michael Ray

Previous studies have shown that magnetic behavior in multilayers formed by repeating a bilayer unit comprised of a ferromagnetic layer and a non-magnetic spacer layer can be affected by small structural differences. For example, a macroscopic property such as giant magnetoresistance (GMR) is believed to depend significantly upon interfacial roughness. In this study, several complimentary structural probes were used to carefully characterize the structure of several sputtered multilayer systems-Co/Ag, Co/Cu, Co/Mo, Fe/Si, and Fe//[FeSi/]. X-ray diffraction (XRD) studies were used to examine the long-range structural order of the multilayers perpendicular to the plane of the layers. Transmission electron diffraction (TED) studies were used to probe the long-range order parallel to the layer plane. X-ray Absorption Fine Structure (XAFS) studies were used to determine the average local structural environment of the ferromagnetic atoms. For the Co/X systems, a simple correlation between crystal structure and saturation magnetization is discovered for the Co/Mo system. For the Fe/X systems, direct evidence of an Fe-silicide is found for the /[FeSi/] spacer layer but not for the Si spacer layer. Additionally, differences were observed in the magnetic behavior between the Fe in the nominally pure Fe layer and the Fe contained in the /[FeSi/] spacer layers.

A review of hybrid implicit explicit finite difference time domain method

NASA Astrophysics Data System (ADS)

Chen, Juan

2018-06-01

The finite-difference time-domain (FDTD) method has been extensively used to simulate varieties of electromagnetic interaction problems. However, because of its Courant-Friedrich-Levy (CFL) condition, the maximum time step size of this method is limited by the minimum size of cell used in the computational domain. So the FDTD method is inefficient to simulate the electromagnetic problems which have very fine structures. To deal with this problem, the Hybrid Implicit Explicit (HIE)-FDTD method is developed. The HIE-FDTD method uses the hybrid implicit explicit difference in the direction with fine structures to avoid the confinement of the fine spatial mesh on the time step size. So this method has much higher computational efficiency than the FDTD method, and is extremely useful for the problems which have fine structures in one direction. In this paper, the basic formulations, time stability condition and dispersion error of the HIE-FDTD method are presented. The implementations of several boundary conditions, including the connect boundary, absorbing boundary and periodic boundary are described, then some applications and important developments of this method are provided. The goal of this paper is to provide an historical overview and future prospects of the HIE-FDTD method.

Fine tuning and orientation control of surface Cu complexes on TiO2(110) premodified with mercapto compounds: the effect of different mercapto group positions.

PubMed

Takakusagi, Satoru; Nojima, Hirotaka; Ariga, Hiroko; Uehara, Hiromitsu; Miyazaki, Kotaro; Chun, Wang-Jae; Iwasawa, Yasuhiro; Asakura, Kiyotaka

2013-09-07

Three-dimensional structures of vacuum-deposited Cu species formed on TiO2(110) surfaces premodified with three mercaptobenzoic acid (MBA) isomers were studied using polarization-dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS). We explored the possibility of fine tuning and orientation control of the surface Cu structures, including their coordination and configuration against the surface, according to the different mercapto group positions of the three MBA isomers (o-, m-, and p-MBA). Almost linear S-Cu-O (lattice O of TiO2) surface compounds were formed on the three MBA-modified TiO2(110) surfaces; however, the orientation of the Cu species on the o- and m-MBA-modified TiO2(110) surfaces (40-45° inclined from the surface normal) was different from that on the p-MBA-modified TiO2(110) surface (60° from the surface normal). This work suggests that the selection of a different MBA isomer for premodification of a single crystal TiO2(110) surface enables fine tuning and orientation control of surface Cu complexes.

(1,3;1,4)-β-Glucan Biosynthesis by the CSLF6 Enzyme: Position and Flexibility of Catalytic Residues Influence Product Fine Structure.

PubMed

Dimitroff, George; Little, Alan; Lahnstein, Jelle; Schwerdt, Julian G; Srivastava, Vaibhav; Bulone, Vincent; Burton, Rachel A; Fincher, Geoffrey B

2016-04-05

Cellulose synthase-like F6 (CslF6) genes encode polysaccharide synthases responsible for (1,3;1,4)-β-glucan biosynthesis in cereal grains. However, it is not clear how both (1,3)- and (1,4)-linkages are incorporated into a single polysaccharide chain and how the frequency and arrangement of the two linkage types that define the fine structure of the polysaccharide are controlled. Through transient expression in Nicotiana benthamiana leaves, two CSLF6 orthologs from different cereal species were shown to mediate the synthesis of (1,3;1,4)-β-glucans with very different fine structures. Chimeric cDNA constructs with interchanged sections of the barley and sorghum CslF6 genes were developed to identify regions of the synthase enzyme responsible for these differences. A single amino acid residue upstream of the TED motif in the catalytic region was shown to dramatically change the fine structure of the polysaccharide produced. The structural basis of this effect can be rationalized by reference to a homology model of the enzyme and appears to be related to the position and flexibility of the TED motif in the active site of the enzyme. The region and amino acid residue identified provide opportunities to manipulate the solubility of (1,3;1,4)-β-glucan in grains and vegetative tissues of the grasses and, in particular, to enhance the solubility of dietary fibers that are beneficial to human health.

Wrinkle structures—a critical review

NASA Astrophysics Data System (ADS)

Porada, Hubertus; Bouougri, El Hafid

2007-04-01

In this paper, a variety of so-called 'wrinkle structures' is reviewed in an attempt to help distinguish between crinkly decorations arising from physical processes that acted on siliciclastic bedding surfaces, and true microbially induced 'wrinkle structures'. Two types of small-scale, microbially induced sedimentary structures are prominent due to their distinct geometry and mode of occurrence: (1) 'elephant skin' textures, characterized by reticulate patterns of sharp-crested ridges forming mm- to cm-scale polygons, occurring on argillite or argillaceous veneers above fine-grained sandstone and likely reflecting growth structures of microbial, mats (2) 'Kinneyia' structures, characterized by mm-scale flat-topped, winding ridges and intervening troughs and pits, sometimes resembling small-scale interference ripples. 'Kinneyia' structures usually occur on upper surfaces of siltstone/sandstone beds, themselves frequently event deposits, and are thought to have formed beneath microbial mats. Additionally, more linear variations of mat growth structures, partly resembling small-scale 'α-petees' may be developed. Finally, some wrinkly structures resulting from tractional mat deformation or mat slumping are occasionally preserved. These may appear as arcuate belts of non-penetrative, small-scale folds or as wrinkled bulges on otherwise flat surfaces. 'Wrinkle structures' as indicators for the former presence of mats gain in importance if other mat-related structures are additionally observed in the same clastic succession, e.g. 'sand chips' (sandy intraclasts) or spindle-shaped or sinuously curved to circular sand cracks, frequently combined in networks. Furthermore, appropriate lithologies and facies are required. For instance, if compared with the distribution of modern cohesive microbial mats, laminated siltstone/argillite with intercalated siltstone/sandstone beds representing event deposits in tidal flat successions would be compatible with microbial mat development. Within a variety of physically induced small-scale wrinkly structures, miniature load structures may, above all, be misinterpreted as microbially induced 'wrinkle structures', due to their similar size and appearance, and their comparatively frequent occurrence.

Inbreeding Avoidance Drives Consistent Variation of Fine-Scale Genetic Structure Caused by Dispersal in the Seasonal Mating System of Brandt’s Voles

PubMed Central

Liu, Xiao Hui; Yue, Ling Fen; Wang, Da Wei; Li, Ning; Cong, Lin

2013-01-01

Inbreeding depression is a major evolutionary and ecological force influencing population dynamics and the evolution of inbreeding-avoidance traits such as mating systems and dispersal. Mating systems and dispersal are fundamental determinants of population genetic structure. Resolving the relationships among genetic structure, seasonal breeding-related mating systems and dispersal will facilitate our understanding of the evolution of inbreeding avoidance. The goals of this study were as follows: (i) to determine whether females actively avoided mating with relatives in a group-living rodent species, Brandt’s voles (Lasiopodomys brandtii), by combined analysis of their mating system, dispersal and genetic structure; and (ii) to analyze the relationships among the variation in fine-genetic structure, inbreeding avoidance, season-dependent mating strategies and individual dispersal. Using both individual- and population-level analyses, we found that the majority of Brandt’s vole groups consisted of close relatives. However, both group-specific FISs, an inbreeding coefficient that expresses the expected percentage rate of homozygosity arising from a given breeding system, and relatedness of mates showed no sign of inbreeding. Using group pedigrees and paternity analysis, we show that the mating system of Brandt’s voles consists of a type of polygyny for males and extra-group polyandry for females, which may decrease inbreeding by increasing the frequency of mating among distantly-related individuals. The consistent variation in within-group relatedness, among-group relatedness and fine-scale genetic structures was mostly due to dispersal, which primarily occurred during the breeding season. Biologically relevant variation in the fine-scale genetic structure suggests that dispersal during the mating season may be a strategy to avoid inbreeding and drive the polygynous and extra-group polyandrous mating system of this species. PMID:23516435

Preliminary three-dimensional geohydrologic framework of the San Antonio Creek Groundwater Basin, Santa Barbara County, California

NASA Astrophysics Data System (ADS)

Cromwell, G.; Sweetkind, D. S.; O'leary, D. R.

2017-12-01

The San Antonio Creek Groundwater Basin is a rural agricultural area that is heavily dependent on groundwater to meet local water demands. The U.S. Geological Survey (USGS) is working cooperatively with Santa Barbara County and Vandenberg Air Force Base to assess the quantity and quality of the groundwater resources within the basin. As part of this assessment, an integrated hydrologic model that will help stakeholders to effectively manage the water resources in the basin is being developed. The integrated hydrologic model includes a conceptual model of the subsurface geology consisting of stratigraphy and variations in lithology throughout the basin. The San Antonio Creek Groundwater Basin is a relatively narrow, east-west oriented valley that is structurally controlled by an eastward-plunging syncline. Basin-fill material beneath the valley floor consists of relatively coarse-grained, permeable, marine and non-marine sedimentary deposits, which are underlain by fine-grained, low-permeability, marine sedimentary rocks. To characterize the system, surficial and subsurface geohydrologic data were compiled from geologic maps, existing regional geologic models, and lithology and geophysical logs from boreholes, including two USGS multiple-well sites drilled as part of this study. Geohydrologic unit picks and lithologic variations are incorporated into a three-dimensional framework model of the basin. This basin (model) includes six geohydrologic units that follow the structure and stratigraphy of the area: 1) Bedrock - low-permeability marine sedimentary rocks; 2) Careaga Formation - fine to coarse grained near-shore sandstone; 3) Paso Robles Formation, lower portion - sandy-gravely deposits with clay and limestone; 4) Paso Robles Formation, middle portion - clayey-silty deposits; 5) Paso Robles Formation, upper portion - sandy-gravely deposits; and 6) recent Quaternary deposits. Hydrologic data show that the upper and lower portions of the Paso Robles Formation are the primary grou­ndwater-bearing units within the basin, and that the fine-grained layer within this Formation locally restricts vertical groundwater flow.

Unlocking the Physiochemical Controls on Organic Carbon Dynamics from the Soil Pore- to Core-Scale

NASA Astrophysics Data System (ADS)

Smith, A. P.; Tfaily, M. M.; Bond-Lamberty, B. P.; Todd-Brown, K. E.; Bailey, V. L.

2015-12-01

The physical organization of soil includes pore networks of varying size and connectivity. These networks control microbial access to soil organic carbon (C) by spatially separating microorganisms and C by both distance and size exclusion. The extent to which this spatially isolated C is vulnerable to microbial transformation under hydrologically dynamic conditions is unknown, and limits our ability to predict the source and sink capacity of soils. We investigated the effects of shifting hydrologic connectivity and soil structure on greenhouse gas C emissions from surface soils collected from the Disney Wilderness Preserve (Florida, USA). We subjected intact soil cores and re-packed homogenized soil cores to simulated groundwater rise or precipitation, monitoring their CO2 and CH4 emissions over 24 hours. Soil pore water was then extracted from each core using different suctions to sample water retained by pore throats of different sizes and then characterized by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Greater respiration rates were observed from homogenized cores compared to intact cores, and from soils wet from below, in which the wetting front is driven by capillary forces, filling fine pores first. This suggests that C located in fine pores may turn over via diffusion processes that lead to the colocation of this C with other resources and microorganisms. Both the complexity and concentration of soluble-C increased with decreasing pore size domains. Pore water extracted from homogenized cores had greater C concentrations than from intact cores, with the greatest concentrations in pore waters sampled from very fine pores, highlighting the importance of soil structure in physically protecting C. These results suggest that the spatial separation of decomposers from C is a key mechanism stabilizing C in these soils. Further research is ongoing to accurately represent this protection mechanism, and the conditions under which it breaks down, in new and improved Earth system models.

Redefining fine roots improves understanding of belowground contributions to terrestrial biosphere processes

DOE PAGES

McCormack, M. Luke; Dickie, Ian A.; Eissenstat, David M.; ...

2015-03-10

Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain due to challenges in consistent measurement and interpretation of fine-root systems. We define fine roots as all roots less than or equal to 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. We demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, finemore » roots are separated into either individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine root pool. Furthermore, using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally a ca. 30% reduction from previous estimates assuming a single fine-root pool. In the future we hope to develop tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi in fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand belowground processes in the terrestrial biosphere.« less

Comparison of detonation spreading in pressed ultra-fine and nano-TATB

NASA Astrophysics Data System (ADS)

Olles, Joseph; Wixom, Ryan; Knepper, Robert; Yarrington, Cole; Patel, Rajen; Stepanov, Victor

2017-06-01

Detonation spreading behavior in insensitive high explosives is an important performance characteristic for initiation-train design. In the past, several variations of the floret test have been used to study this phenomenon. Commonly, dent blocks or multi-fiber optical probes were employed for reduced cost and complexity. We devised a floret-like test, using minimal explosive material, to study the detonation spreading in nano-TATB as compared to ultra-fine TATB. Our test uses a streak camera, combined with photonic Doppler velocimetry, to image the breakout timing and quantify the output particle velocity. The TATB acceptor pellets are initiated using an explosively-driven aluminum flyer with a well characterized velocity. We characterized the two types of TATB by assessing purity, particle morphology, and the microstructure of the consolidated pellets. Our results align with published data for ultra-fine TATB, however the nano-TATB shows a distinct difference where output has a strong dependence on density. The results indicate that control over pellet pore size and pressing density may be used to optimize detonation spreading behavior.

Development of flexible SAW sensors for non-destructive testing of structure

NASA Astrophysics Data System (ADS)

Takpara, R.; Duquennoy, M.; Courtois, C.; Gonon, M.; Ouaftouh, M.; Martic, G.; Rguiti, M.; Jenot, F.; Seronveaux, L.; Pelegris, C.

2016-02-01

In order to accurately examine structures surfaces, it is interesting to use surface SAW (Surface Acoustic Wave). Such waves are well suited for example to detect early emerging cracks or to test the quality of a coating. In addition, when coatings are thin or when emergent cracks are precocious, it is necessary to excite surface waves beyond 10MHz. Finally, when structures are not flat, it makes sense to have flexible or conformable sensors for their characterization. To address this problem, we propose to develop SAW type of interdigital sensors (or IDT for InterDigital Transducer), based on flexible piezoelectric plates. Initially, in order to optimize these sensors, we modeled the behavior of these sensors and identified the optimum characteristic sizes. In particular, the thickness of the piezoelectric plate and the width of the interdigital electrodes have been studied. Secondly, we made composites based on barium titanate foams in order to have flexible piezoelectric plates and to carry out thereafter sensors. Then, we studied several techniques in order to optimize the interdigitated electrodes deposition on this type of material. One of the difficulties concerns the fineness of these electrodes because the ratio between the length (typically several millimeters) and the width (a few tens of micrometers) of electrodes is very high. Finally, mechanical, electrical and acoustical characterizations of the sensors deposited on aluminum substrates were able to show the quality of our achievement.

Compact cell-centered discretization stencils at fine-coarse block structured grid interfaces

NASA Astrophysics Data System (ADS)

Pletzer, Alexander; Jamroz, Ben; Crockett, Robert; Sides, Scott

2014-03-01

Different strategies for coupling fine-coarse grid patches are explored in the context of the adaptive mesh refinement (AMR) method. We show that applying linear interpolation to fill in the fine grid ghost values can produce a finite volume stencil of comparable accuracy to quadratic interpolation provided the cell volumes are adjusted. The volume of fine cells expands whereas the volume of neighboring coarse cells contracts. The amount by which the cells contract/expand depends on whether the interface is a face, an edge, or a corner. It is shown that quadratic or better interpolation is required when the conductivity is spatially varying, anisotropic, the refinement ratio is other than two, or when the fine-coarse interface is concave.

Reproductive biology in Anophelinae mosquitoes (Diptera, Culicidae): Fine structure of the female accessory gland.

PubMed

Laghezza Masci, Valentina; Di Luca, Marco; Gambellini, Gabriella; Taddei, Anna Rita; Belardinelli, Maria Cristina; Guerra, Laura; Mazzini, Massimo; Fausto, Anna Maria

2015-07-01

The morphology and ultrastructure of female accessory reproductive glands of Anopheles maculipennis s.s., Anopheles labranchiae and Anopheles stephensi were investigated by light and electron microscopy. The reproductive system in these species is characterized by two ovaries, two lateral oviducts, a single spermatheca and a single accessory gland. The gland is globular and has a thin duct which empties into the vagina, near the opening of the spermathecal duct. Significant growth of the accessory reproductive gland is observed immediately after blood meal, but not at subsequent digestion steps. At ultrastructural level, the gland consists of functional glandular units belonging to type 3 ectodermal glands. The secretory cells are elongated and goblet shaped, with most of their cytoplasm and large nucleus in the basal part, close to the basement lamella. Finely fibrous electron-transparent material occupies the secretory cavity that is in contact with the end of a short efferent duct (ductule) emerging from the gland duct. The present study is the first detailed description of female accessory gland ultrastructure in Anophelinae and provides insights into the gland's functional role in the reproductive biology of these insects. Copyright © 2015 Elsevier Ltd. All rights reserved.

Humanoid Mobile Manipulation Using Controller Refinement

NASA Technical Reports Server (NTRS)

Platt, Robert; Burridge, Robert; Diftler, Myron; Graf, Jodi; Goza, Mike; Huber, Eric; Brock, Oliver

2006-01-01

An important class of mobile manipulation problems are move-to-grasp problems where a mobile robot must navigate to and pick up an object. One of the distinguishing features of this class of tasks is its coarse-to-fine structure. Near the beginning of the task, the robot can only sense the target object coarsely or indirectly and make gross motion toward the object. However, after the robot has located and approached the object, the robot must finely control its grasping contacts using precise visual and haptic feedback. This paper proposes that move-to-grasp problems are naturally solved by a sequence of controllers that iteratively refines what ultimately becomes the final solution. This paper introduces the notion of a refining sequence of controllers and characterizes this type of solution. The approach is demonstrated in a move-to-grasp task where Robonaut, the NASA/JSC dexterous humanoid, is mounted on a mobile base and navigates to and picks up a geological sample box. In a series of tests, it is shown that a refining sequence of controllers decreases variance in robot configuration relative to the sample box until a successful grasp has been achieved.

Humanoid Mobile Manipulation Using Controller Refinement

NASA Technical Reports Server (NTRS)

Platt, Robert; Burridge, Robert; Diftler, Myron; Graf, Jodi; Goza, Mike; Huber, Eric

2006-01-01

An important class of mobile manipulation problems are move-to-grasp problems where a mobile robot must navigate to and pick up an object. One of the distinguishing features of this class of tasks is its coarse-to-fine structure. Near the beginning of the task, the robot can only sense the target object coarsely or indirectly and make gross motion toward the object. However, after the robot has located and approached the object, the robot must finely control its grasping contacts using precise visual and haptic feedback. In this paper, it is proposed that move-to-grasp problems are naturally solved by a sequence of controllers that iteratively refines what ultimately becomes the final solution. This paper introduces the notion of a refining sequence of controllers and characterizes this type of solution. The approach is demonstrated in a move-to-grasp task where Robonaut, the NASA/JSC dexterous humanoid, is mounted on a mobile base and navigates to and picks up a geological sample box. In a series of tests, it is shown that a refining sequence of controllers decreases variance in robot configuration relative to the sample box until a successful grasp has been achieved.

Low-temperature formation of crystalline Si:H/Ge:H heterostructures by plasma-enhanced CVD in combination with Ni-nanodots seeding nucleation

NASA Astrophysics Data System (ADS)

Lu, Yimin; Makihara, Katsunori; Takeuchi, Daichi; Ikeda, Mitsuhisa; Ohta, Akio; Miyazaki, Seiichi

2017-06-01

Hydrogenated microcrystalline (µc) Si/Ge heterostructures were prepared on quartz substrates by plasma-enhanced chemical vapor deposition (CVD) from VHF inductively coupled plasma of SiH4 just after GeH4 employing Ni nanodots (NDs) as seeds for crystalline nucleation. The crystallinity of the films and the progress of grain growth were characterized by Raman scattering spectroscopy and atomic force microscopy (AFM), respectively. When the Ge films were grown on Ni-NDs at 250 °C, the growth of µc-Ge films with crystallinity as high as 80% was realized without an amorphous phase near the Ge film/quartz substrate interface. After the subsequent Si film deposition at 250 °C, fine grains were formed in the early stages of film growth on µc-Ge films with compositional mixing (µc-Si0.85Ge0.15:H) caused by the release of large lattice mismatch between c-Si and c-Ge. With further increase in Si:H film thickness, the formation of large grain structures accompanied by fine grains was promoted. These results suggest that crystalline Si/Ge heterojunctions can be used for efficient carrier collection in solar cell application.

Fine structure of the epicytoplasmic eimerid coccidium Acroeimeria pintoi Lainson & Paperna, 1999, a gut parasite of the lizard Ameiva ameiva in north Brazil.

PubMed

Paperna, L; Lainson, R

1999-12-01

An account is given of the fine structure of Acroeimerio pintoi, an epicytoplasmic coccidium infecting the small intestine of the teiid lizard Ameiva ameiva in north Brazil. The merozoile becomes encircled by outgrowths of the host-cell wall which then merge to form a parasitophorous sack in which the parasite continues to develop when this bulges out above the epithelium surface. The account includes a description of merozoites, young meronts and young and mature macrogamonts. The parasitophorous vacuole has a complex tubular system connected to its junction with the host-cell. The parasites are coated with a droplet-like glycocalyx and covered by a fine filamentous layer.

Quark mass variations of nuclear forces, BBN, and all that

NASA Astrophysics Data System (ADS)

Meissner, Ulf-G.

2014-03-01

In this talk, I discuss the modifications of the nuclear forces due to variations of the light quark masses and of the fine structure constant. This is based on the chiral nuclear effective field theory, that successfully describes a large body of data. The generation of the light elements in the Big Bang Nucleosynthesis provides important constraints on these modifications. In addition, I discuss the role of the anthropic principle in the triple-alpha process that underlies carbon and oxygen generation in hot stars. It appears that a fine-tuning of the quark masses and the fine structure constant within 2 to 3 per cent is required to make life on Earth viable. Supported in part by DFG, HGF and the BMBF.

Synergic application of spectroscopic and theoretical methods to the chlorogenic acid structure elucidation

NASA Astrophysics Data System (ADS)

Marković, Svetlana; Tošović, Jelena; Dimitrić Marković, Jasmina M.

2016-07-01

Although chlorogenic acid (5-O-caffeoylquinic acid, 5CQA) is a dietary polyphenol known for its pharmacological and nutritional properties, its structural features have not been completely elucidated. This is the first study whose aim is to contribute to clarification of the 5CQA structure by comparing the experimental and simulated IR, Raman, 1H NMR, 13C NMR, and UV spectra. For this purpose, a comprehensive conformational analysis of 5CQA was performed to reveal its most stable conformations in the gas-state and solution (DMSO and methanol). The lowest-energy conformers were used to predict the spectra at two levels of theory: B3LYP-D3/and M06-2X/6-311+G(d,p) in combination with the CPCM solvation model. Both methods provide very good agreement between all experimental and simulated spectra, thus indicating correct arrangement of the atoms in the 5CQA molecule. The quinic moiety is characterized with directed hydrogen bonds, where the carboxylic hydrogen is not oriented towards the carbonyl oxygen of the carboxylic group, but towards the oxygen of the proximate hydroxyl group. In the gas-state the lowest-energy conformers are characterized with the O4sbnd H4 ⋯ O9‧ hydrogen bond, whereas in the solvated state the structures with the O4sbnd H4 ⋯ O10‧ hydrogen bond prevail. Knowing the fine structural details, i.e. the proper conformation of 5CQA, provides a solid base for all further investigations related to this compound.

Rare variation facilitates inferences of fine-scale population structure in humans.

PubMed

O'Connor, Timothy D; Fu, Wenqing; Mychaleckyj, Josyf C; Logsdon, Benjamin; Auer, Paul; Carlson, Christopher S; Leal, Suzanne M; Smith, Joshua D; Rieder, Mark J; Bamshad, Michael J; Nickerson, Deborah A; Akey, Joshua M

2015-03-01

Understanding the genetic structure of human populations has important implications for the design and interpretation of disease mapping studies and reconstructing human evolutionary history. To date, inferences of human population structure have primarily been made with common variants. However, recent large-scale resequencing studies have shown an abundance of rare variation in humans, which may be particularly useful for making inferences of fine-scale population structure. To this end, we used an information theory framework and extensive coalescent simulations to rigorously quantify the informativeness of rare and common variation to detect signatures of fine-scale population structure. We show that rare variation affords unique insights into patterns of recent population structure. Furthermore, to empirically assess our theoretical findings, we analyzed high-coverage exome sequences in 6,515 European and African American individuals. As predicted, rare variants are more informative than common polymorphisms in revealing a distinct cluster of European-American individuals, and subsequent analyses demonstrate that these individuals are likely of Ashkenazi Jewish ancestry. Our results provide new insights into the population structure using rare variation, which will be an important factor to account for in rare variant association studies. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Rocket experiments for spectral estimation of electron density fine structure in the auroral and equatorial ionosphere and preliminary results

NASA Technical Reports Server (NTRS)

Tomei, B. A.; Smith, L. G.

1986-01-01

Sounding rockets equipped to monitor electron density and its fine structure were launched into the auroral and equatorial ionosphere in 1980 and 1983, respectively. The measurement electronics are based on the Langmuir probe and are described in detail. An approach to the spectral analysis of the density irregularities is addressed and a software algorithm implementing the approach is given. Preliminary results of the analysis are presented.

Re/Os constraint on the time variability of the fine-structure constant.

PubMed

Fujii, Yasunori; Iwamoto, Akira

2003-12-31

We argue that the accuracy by which the isochron parameters of the decay 187Re-->187Os are determined by dating iron meteorites may constrain the possible time dependence of the decay rate and hence of the fine-structure constant alpha, not directly but only in a model-dependent manner. From this point of view, some of the attempts to analyze the Oklo constraint and the results of the quasistellar-object absorption lines are reexamined.

A correlational method to concurrently measure envelope and temporal fine structure weights: Effects of age, cochlear pathology, and spectral shaping1

PubMed Central

Fogerty, Daniel; Humes, Larry E.

2012-01-01

The speech signal may be divided into spectral frequency-bands, each band containing temporal properties of the envelope and fine structure. This study measured the perceptual weights for the envelope and fine structure in each of three frequency bands for sentence materials in young normal-hearing listeners, older normal-hearing listeners, aided older hearing-impaired listeners, and spectrally matched young normal-hearing listeners. The availability of each acoustic property was independently varied through noisy signal extraction. Thus, the full speech stimulus was presented with noise used to mask six different auditory channels. Perceptual weights were determined by correlating a listener’s performance with the signal-to-noise ratio of each acoustic property on a trial-by-trial basis. Results demonstrate that temporal fine structure perceptual weights remain stable across the four listener groups. However, a different weighting typography was observed across the listener groups for envelope cues. Results suggest that spectral shaping used to preserve the audibility of the speech stimulus may alter the allocation of perceptual resources. The relative perceptual weighting of envelope cues may also change with age. Concurrent testing of sentences repeated once on a previous day demonstrated that weighting strategies for all listener groups can change, suggesting an initial stabilization period or susceptibility to auditory training. PMID:22978896

Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

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

Pentlehner, D.; Slenczka, A., E-mail: alkwin.slenczka@chemie.uni-regensburg.de

2015-01-07

Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broadmore » (Δν > 100 cm{sup −1}) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time.« less

Fine-scale human genetic structure in Western France.

PubMed

Karakachoff, Matilde; Duforet-Frebourg, Nicolas; Simonet, Floriane; Le Scouarnec, Solena; Pellen, Nadine; Lecointe, Simon; Charpentier, Eric; Gros, Françoise; Cauchi, Stéphane; Froguel, Philippe; Copin, Nane; Le Tourneau, Thierry; Probst, Vincent; Le Marec, Hervé; Molinaro, Sabrina; Balkau, Beverley; Redon, Richard; Schott, Jean-Jacques; Blum, Michael Gb; Dina, Christian

2015-06-01

The difficulties arising from association analysis with rare variants underline the importance of suitable reference population cohorts, which integrate detailed spatial information. We analyzed a sample of 1684 individuals from Western France, who were genotyped at genome-wide level, from two cohorts D.E.S.I.R and CavsGen. We found that fine-scale population structure occurs at the scale of Western France, with distinct admixture proportions for individuals originating from the Brittany Region and the Vendée Department. Genetic differentiation increases with distance at a high rate in these two parts of Northwestern France and linkage disequilibrium is higher in Brittany suggesting a lower effective population size. When looking for genomic regions informative about Breton origin, we found two prominent associated regions that include the lactase region and the HLA complex. For both the lactase and the HLA regions, there is a low differentiation between Bretons and Irish, and this is also found at the genome-wide level. At a more refined scale, and within the Pays de la Loire Region, we also found evidence of fine-scale population structure, although principal component analysis showed that individuals from different departments cannot be confidently discriminated. Because of the evidence for fine-scale genetic structure in Western France, we anticipate that rare and geographically localized variants will be identified in future full-sequence analyses.

Role of Microstructure on the Performance of UHTCs

NASA Technical Reports Server (NTRS)

Johnson, Sylvia M.; Gasch, Matthew J.; Lawson, John W.; Gusman, Michael I.; Stackpoole, Mairead

2010-01-01

We have investigated a number of methods to control microstructure. We have routes to form: a) in situ "composites" b) Very fine microstructures. Arcjet testing and other characterization of monolithic materials. Control oxidation through microstructure and composition. Beginning to incorporate these materials as matrices for composites. Modeling effort to facilitate material design and characterization.

Optimization of the EMI shielding effectiveness of fine and ultrafine POFA powder mix with OPC powder using Flower Pollination Algorithm

NASA Astrophysics Data System (ADS)

Narong, L. C.; Sia, C. K.; Yee, S. K.; Ong, P.; Zainudin, A.; Nor, N. H. M.; Kasim, N. A.

2017-01-01

In order to solve the electromagnetic interference (EMI) issue and provide a new application for palm oil fuel ash (POFA), POFA was used as the cement filler for enhancing the EMI absorption of cement-based composites. POFA was refined by using water precipitation for 24 hours to remove the filthiness and distinguish the layer 1 (floated) and layer 2 (sink) of POFA. Both layers POFA were dried for 24 hours at 100 ± 5 °C and grind separately for sieve at 140 μm (Fine) and 45 цш sizes (Ultrafine). The micro structure and element content of the both layers POFA were characterized by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) respectively. The results showed layer 1 POFA has potentialities for EMI shielding effectiveness (SE) due to its higher carbon content and porous structure. The study reveals that EMI SE also influenced by the particle size of POFA, where smaller particle size can increase 5 % to 13 % of EMI SE. When the specimen consists of 50% POFA with passing through 45 μm sieve, the EMI was shield -13.08 dB in between 50 MHz to 2 GHz range. Flower Pollination Algorithm (FPA) proves that POFA passing 45 μm sieve with 50% mixed to OPC is optimal parameter. The error between experimental and FPA simulation data is below 1.2 for both layers POFA.

Discovery of Finely Structured Dynamic Solar Corona Observed in the Hi-C Telescope

NASA Technical Reports Server (NTRS)

Winebarger, A.; Cirtain, J.; Golub, L.; DeLuca, E.; Savage, S.; Alexander, C.; Schuler, T.

2014-01-01

In the summer of 2012, the High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to be smoothly varying, i.e. have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70 percent of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent.

DISCOVERY OF FINELY STRUCTURED DYNAMIC SOLAR CORONA OBSERVED IN THE Hi-C TELESCOPE

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

Winebarger, Amy R.; Cirtain, Jonathan; Savage, Sabrina

In the Summer of 2012, the High-resolution Coronal Imager (Hi-C) flew on board a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to bemore » smoothly varying, i.e., have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70% of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent.« less

Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH( X ˜ / A ˜ ) products in the B-band photodissociation of H2O

NASA Astrophysics Data System (ADS)

Zhou, Linsen; Xie, Daiqian; Guo, Hua

2015-03-01

A detailed quantum mechanical characterization of the photodissociation dynamics of H2O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH( X ˜ / A ˜ ) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH( X ˜ , v = 0) exhibit very different characteristics. The A' states, produced mostly via the B ˜ → X ˜ conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B ˜ → A ˜ Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH( X ˜ ) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B ˜ → X ˜ non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH( A ˜ ) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

Signatures of non-adiabatic dynamics in the fine-structure state distributions of the OH(X̃/Ã) products in the B-band photodissociation of H2O.

PubMed

Zhou, Linsen; Xie, Daiqian; Guo, Hua

2015-03-28

A detailed quantum mechanical characterization of the photodissociation dynamics of H2O at 121.6 nm is presented. The calculations were performed using a full-dimensional wave packet method on coupled potential energy surfaces of all relevant electronic states. Our state-to-state model permits a detailed analysis of the OH(X̃/Ã) product fine-structure populations as a probe of the non-adiabatic dissociation dynamics. The calculated rotational state distributions of the two Λ-doublet levels of OH(X̃, v = 0) exhibit very different characteristics. The A' states, produced mostly via the B̃→X̃ conical intersection pathway, have significantly higher populations than the A″ counterparts, which are primarily from the B̃→Ã Renner-Teller pathway. The former features a highly inverted and oscillatory rotational state distribution, while the latter has a smooth distribution with much less rotational excitation. In good agreement with experiment, the calculated total OH(X̃) rotational state distribution and anisotropy parameters show clear even-odd oscillations, which can be attributed to a quantum mechanical interference between waves emanating from the HOH and HHO conical intersections in the B̃→X̃ non-adiabatic pathway. On the other hand, the experiment-theory agreement for the OH(Ã) fragment is also satisfactory, although some small quantitative differences suggest remaining imperfections of the ab initio based potential energy surfaces.

Fine structures of azimuthal correlations of two gluons in the glasma

NASA Astrophysics Data System (ADS)

Zhang, Hengying; Zhang, Donghai; Zhao, Yeyin; Xu, Mingmei; Pan, Xue; Wu, Yuanfang

2018-02-01

We investigate the azimuthal correlations of the glasma in p-p collisions at √{sNN}=7 TeV by using the color glass condensate (CGC) formalism. As expected, the azimuthal correlations show two peaks at Δ ϕ =0 and π , which represent collimation production in the CGC. Beyond that, azimuthal correlations show fine structures, i.e., bumps or shoulders between the two peaks, when at least one gluon has small x . The structures are demonstrated to be associated with saturation momentum and likely appear at transverse momentum around 2 Qsp=1.8 GeV /c .

Multi-modal STEM-based tomography of HT-9 irradiated in FFTF

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

Field, Kevin G.; Eftink, Benjamin Paul; Saleh, Tarik A.

Under irradiation, point defects and defect clusters can agglomerate to form extended two and three dimensional (2D/3D) defects. The formation of defects can be synergistic in nature with one defect or defect-type influencing the formation and/or evolution of another. The resul is a need exists to perform advanced characterization where microstructures are accurately reproduced in 3D. Here, HT-9 neutron irradiated in the FFTF was used to evaluate the ability of multi-tilt STEM-based tomography to reproduce the fine-scale radiation-induced microstructure. High-efficiency STEM-EDS was used to provide both structural and chemical information during the 3D reconstruction. The results show similar results tomore » a previous two-tilt tomography study on the same material; the α' phase is denuded around the Ni-Si-Mn rich G-phase and cavities. It is concluded both tomography reconstruction techniques are readily viable and could add significant value to the advanced characterization capabilities for irradiated materials.« less