In-situ observation of structure formation in polymer processing

International Nuclear Information System (INIS)

Murase, Hiroki

2009-01-01

In-situ X-ray scattering in polymer processing is a crucial method to elucidate the mechanism of structure formation in the process. Fiber spinning is one such process primarily imposing extensional deformation on polymeric melt at the spin-line during rapid cooling. In-situ small-angle X-ray scattering using synchrotron radiation on the spinning process allows direct observation of the transient structure developing in the process. (author)

Towards functionalization of graphene: in situ study of the nucleation of copper-phtalocyanine on graphene

OpenAIRE

Schwarz, Daniel; Henneke, Caroline; Kumpf, Christian

2016-01-01

Molecular films present an elegant way for the uniform functionalization or doping of graphene. Here, we present an in situ study on the initial growth of copper phthalocyanine (CuPc) on epitaxial graphene on Ir(111). We followed the growth up to a closed monolayer with low energy electron microscopy and selected area electron diffraction (μLEED). The molecules coexist on graphene in a disordered phase without long-range order and an ordered crystalline phase. The local topography of the grap...

The adsorption of methanol and water on SAPO-34: in situ and ex situ X-ray diffraction studies

DEFF Research Database (Denmark)

Wragg, David S.; Johnsen, Rune; Norby, Poul

2010-01-01

The adsorption of methanol on SAPO-34 has been studied using a combination of in situ synchrotron powder X-ray diffraction to follow the process and ex situ high resolution powder diffraction to determine the structure. The unit cell volume of SAPO-34 is found to expand by 0.5% during methanol ad...

In-situ studies of bulk deformation structures: Static properties under load and dynamics during deformation

DEFF Research Database (Denmark)

Jakobsen, Bo

2006-01-01

The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (model system for cell forming pure fcc metals. Anovel synchrotron...... grains in polycrystalline samples during tensile deformation. We have shown that the resulting 3D reciprocal space maps from tensile deformed copper comprise a pronounced structure, consisting of bright sharp peaks superimposed on a cloud of enhanced intensity. Based on the integrated intensity......, the width of the peaks, and spatial scanning experiments it is concluded that the individual peaks arise from individual dislocation-free regions (the subgrains) in the dislocation structure. The cloud is attributed to the dislocation rich walls. Samples deformed to 2% tensile strain were investigated under...

In Situ Atomic Force Microscopy Studies on Nucleation and Self-Assembly of Biogenic and Bio-Inspired Materials

Directory of Open Access Journals (Sweden)

Cheng Zeng

2017-08-01

Full Text Available Through billions of years of evolution, nature has been able to create highly sophisticated and ordered structures in living systems, including cells, cellular components and viruses. The formation of these structures involves nucleation and self-assembly, which are fundamental physical processes associated with the formation of any ordered structure. It is important to understand how biogenic materials self-assemble into functional and highly ordered structures in order to determine the mechanisms of biological systems, as well as design and produce new classes of materials which are inspired by nature but equipped with better physiochemical properties for our purposes. An ideal tool for the study of nucleation and self-assembly is in situ atomic force microscopy (AFM, which has been widely used in this field and further developed for different applications in recent years. The main aim of this work is to review the latest contributions that have been reported on studies of nucleation and self-assembly of biogenic and bio-inspired materials using in situ AFM. We will address this topic by introducing the background of AFM, and discussing recent in situ AFM studies on nucleation and self-assembly of soft biogenic, soft bioinspired and hard materials.

Study of quark structure functions

International Nuclear Information System (INIS)

Dao, F.T.; Flaminio, E.; Lai, K.; Metcalf, M.; Wang, L.

1977-01-01

The quark structure functions of the proton are determined through a combined analysis of the reactions pN → ll-barX and eN → eX. The valence-quark structure function of the pion is also given by analyzing the πN → μμ-barX data measured by the Branson et al

In-situ TEM studies of microstructure evolution under ion irradiation for nuclear engineering applications

International Nuclear Information System (INIS)

Kaoumi, D.

2011-01-01

One of the difficulties of studying processes occurring under irradiation (in a reactor environment) is the lack of kinetics information since usually samples are examined ex situ (i.e. after irradiation) so that only snapshots of the process are available. Given the dynamic nature of the phenomena, direct in situ observation is invaluable for better understanding the mechanisms, kinetics and driving forces of the processes involved. This can be done using in situ ion irradiation in a TEM at the IVEM facility at Argonne National Laboratory which, in the USA, is a unique facility. To predict the in reactor behavior of alloys, it is essential to understand the basic mechanisms of radiation damage formation (loop density, defect interactions) and accumulation (loop evolution, precipitation or dissolution of second phases etc.). In-situ Ion-irradiation in a TEM has proven a very good tool for that purpose as it allows for the direct determination of the formation and evolution of irradiation-induced damage and the spatial correlation of the defect structures with the pre-existing microstructure (including lath boundaries, network dislocations and carbides) as a function of dose, dose rate, temperature and ion type. Using this technique, different aspects of microstructure evolution under irradiation were studied, such as defect cluster formation and evolution as a function of dose in advanced Ferritic/Martensitic (F/M) steels, the irradiation stability of precipitates in Oxide Dispersion Strengthened (ODS) steels, and irradiation-induced grain-growth. Such studies will be reported in this presentation

In-Situ TEM Study of Interface Sliding and Migration in an Ultrafine Lamellar Structure

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L M

2005-12-06

The instability of interfaces in an ultrafine TiAl-({gamma})/Ti{sub 3}Al-({alpha}{sub 2}) lamellar structure by straining at room temperature has been investigated using in-situ straining techniques performed in a transmission electron microscope. The purpose of this study is to obtain experimental evidence to support the creep mechanisms based upon the interface sliding in association with a cooperative movement of interfacial dislocations previously proposed to interpret the nearly linear creep behavior observed from ultrafine lamellar TiAl alloys. The results have revealed that both the sliding and migration of lamellar interfaces can take place simultaneously as a result of the cooperative movement of interfacial dislocations.

Determining the in situ concrete strength of existing structures for assessing their structural safety

NARCIS (Netherlands)

Steenbergen, R.D.J.M.; Vervuurt, A.H.J.M.

2012-01-01

EN 13791 applies when assessing the in situ compressive strength of structures and precast concrete components. According to the code itself, it may be adopted when doubt arises about the compressive strength of a concrete. For assessing the structural safety of existing structures, however, the

A density functional study of backbone structures of polydiacetylene: destabilization of butatriene structure

International Nuclear Information System (INIS)

Katagiri, Hideki; Shimoi, Yukihiro; Abe, Shuji

2004-01-01

Backbone structures of polydiacetylene are studied with first-principles electronic structure method using plane-waves within generalized gradient approximation (GGA) of density functional theory. In spin-restricted calculations a coarse k-point sampling gives a potential energy curve with two local minima corresponding to acetylene and butatriene structures. However, the potential barrier between the two structures rapidly decreases with increasing number of k-points, which results in destabilization of the butatriene structure. Spin polarization effects also destabilize the butatriene structure, inducing atom-centered spin-density-wave state. These potential energies were compared with those obtained by Hartree-Fock, density functional within local density approximation (LDA) and GGA, and hybrid density functional methods using a gaussian basis set. The comparison shows that the density functional methods within LDA and GGA favor the destabilization of the butatriene structure in contrast to the Hartree-Fock method

In-situ oxidation study of Pd(100) by surface x-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Kilic, Volkan; Franz, Dirk; Stierle, Andreas [AG Grenzflaechen, Universitaet Siegen (Germany); Martin, Natalia; Lundgren, Edvin [Department of Synchrotron Radiation Research, Lund University (Sweden); Mantilla, Miguel [MPI fuer Metallforschung, Stuttgart (Germany)

2011-07-01

The oxidation of the Pd(100) surface at oxygen pressures in the 10{sup -6} mbar to 10{sup 3} mbar range and temperatures up to 1000 K has been studied in-situ by surface x-ray diffraction (SXRD). The SXRD experiments were performed at the MPI beamline at the Angstrom Quelle Karlsruhe (ANKA). We present the surface and crystal truncation rod (CTR) data from the ({radical}(5) x {radical}(5)) surface layer. We show that the transformation from the surface oxide to PdO bulk oxide can be observed in-situ under specific pressure and temperature conditions. We compare our results with previously proposed structure models based on low energy electron diffraction (LEED) I(V) curves and density functional theory calculations. Finally, we elucidate the question of commensurability of the surface oxide layer with respect to the Pd(100) substrate.

Desorption of hydrogen from magnesium hydride: in-situ electron diffraction study

International Nuclear Information System (INIS)

Paik, B.; Jones, I.P.; Walton, A.; Mann, V.; Book, D.; Harris, I.R.

2009-01-01

The dynamics of a phase change has been studied where electron beam in Transmission Electron Microscope (TEM) has been used to transform MgH 2 into magnesium. A combination of in-situ Electron Diffraction (ED) and an in-situ Electron Energy Loss Spectroscopy (EELS) study under ED mode describes the phase transformation in terms of, respectively, change in the crystal structure and Plasmon energy shift. The orientation relation [001] MgH2 //[-2110] Mg and (-110) MgH2 //(0001) Mg , obtained from the ED study, has been used to propose a model for the movements of magnesium atoms in the structural change to describe the dynamics of the process. The in-situ EELS study has been compared with the existing H-desorption model. The study aims to describe the sorption dynamics of hydrogen in MgH 2 which is a base material for a number of promising hydrogen storage systems. (author)

High throughput in situ scattering of roll-to-roll coated functional polymer films

DEFF Research Database (Denmark)

Andreasen, Jens Wenzel

2017-01-01

The development of conjugated polymers for organic electronics and photovoltaics has relied heavily on advanced X-ray scattering techniques almost since the earliest studies in the field. Almost from the beginning, structural studies focused on how the polymers self-organize in thin films......, and the relation between chemical configuration of the polymer, structure and performance. This chapter presents the latest developments where structural analysis is applied as in situ characterization of structure formation during roll-to-roll coating of photoactive layers for solar cells....

Enhanced functional connectivity properties of human brains during in-situ nature experience.

Science.gov (United States)

Chen, Zheng; He, Yujia; Yu, Yuguo

2016-01-01

In this study, we investigated the impacts of in-situ nature and urban exposure on human brain activities and their dynamics. We randomly assigned 32 healthy right-handed college students (mean age = 20.6 years, SD = 1.6; 16 males) to a 20 min in-situ sitting exposure in either a nature (n = 16) or urban environment (n = 16) and measured their Electroencephalography (EEG) signals. Analyses revealed that a brief in-situ restorative nature experience may induce more efficient and stronger brain connectivity with enhanced small-world properties compared with a stressful urban experience. The enhanced small-world properties were found to be correlated with "coherent" experience measured by Perceived Restorativeness Scale (PRS). Exposure to nature also induces stronger long-term correlated activity across different brain regions with a right lateralization. These findings may advance our understanding of the functional activities during in-situ environmental exposures and imply that a nature or nature-like environment may potentially benefit cognitive processes and mental well-being.

The growth and electronic structure of azobenzene-based functional molecules on layered crystals

International Nuclear Information System (INIS)

Iwicki, J; Ludwig, E; Buck, J; Kalläne, M; Kipp, L; Rossnagel, K; Köhler, F; Herges, R

2012-01-01

In situ ultraviolet photoelectron spectroscopy is used to study the growth of ultrathin films of azobenzene-based functional molecules (azobenzene, Disperse Orange 3 and a triazatriangulenium platform with an attached functional azo-group) on the layered metal TiTe 2 and on the layered semiconductor HfS 2 at liquid nitrogen temperatures. Effects of intermolecular interactions, of the substrate electronic structure, and of the thermal energy of the sublimated molecules on the growth process and on the adsorbate electronic structure are identified and discussed. A weak adsorbate-substrate interaction is particularly observed for the layered semiconducting substrate, holding the promise of efficient molecular photoswitching.

Studying Membrane Protein Structure and Function Using Nanodiscs

DEFF Research Database (Denmark)

Huda, Pie

The structure and dynamic of membrane proteins can provide valuable information about general functions, diseases and effects of various drugs. Studying membrane proteins are a challenge as an amphiphilic environment is necessary to stabilise the protein in a functionally and structurally relevant...... form. This is most typically achieved through the use of detergent based reconstitution systems. However, time and again such systems fail to provide a suitable environment causing aggregation and inactivation. Nanodiscs are self-assembled lipoproteins containing two membrane scaffold proteins...... and a lipid bilayer in defined nanometer size, which can act as a stabiliser for membrane proteins. This enables both functional and structural investigation of membrane proteins in a detergent free environment which is closer to the native situation. Understanding the self-assembly of nanodiscs is important...

In Situ Structural Characterization of Ferric Iron Dimers in Aqueous Solutions

DEFF Research Database (Denmark)

Zhu, Mengqiang; Puls, Brendan W.; Frandsen, Cathrine

2013-01-01

The structure of ferric iron (Fe3+) dimers in aqueous solutions has long been debated. In this work, we have determined the dimer structure in situ in aqueous solutions using extended X-ray absorption fine structure (EXAFS) spectroscopy. An Fe K-edge EXAFS analysis of 0.2 M ferric nitrate solutions...... at pH 1.28–1.81 identified a Fe–Fe distance at ∼3.6 Å, strongly indicating that the dimers take the μ-oxo form. The EXAFS analysis also indicates two short Fe–O bonds at ∼1.80 Å and ten long Fe–O bonds at ∼2.08 Å, consistent with the μ-oxo dimer structure. The scattering from the Fe–Fe paths interferes...... confirmed by Mössbauer analyses of analogous quick frozen solutions. This work also explores the electronic structure and the relative stability of the μ-oxo dimer in a comparison to the dihydroxo dimer using density function theory (DFT) calculations. The identification of such dimers in aqueous solutions...

Modular in situ-Functionalization Strategy: Multicomponent Polymerization via Palladium/Norbornene Cooperative Catalysis.

Science.gov (United States)

Yoon, Ki-Young; Dong, Guangbin

2018-05-23

Herein, we report the palladium/norbornene cooperatively catalyzed polymerization, which simplifies synthesis of functional aromatic polymers, including conjugated polymers. Specifically, an A2B2C-type multicomponent polymerization is developed using ortho-amination/ipso-alkynylation reaction for preparing various amine-functionalized arylacetylene-containing polymers. Within a single catalytic cycle, the amine side-chains are site-selectively installed in situ via C-H activation during the polymerization process, which represents a major difference from conventional cross-coupling polymerizations. This in situ-functionalization strategy enables modular incorporation of functional side-chains from simple monomers, thereby conveniently affording a diverse range of functional polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-situ poling and structurization of piezoelectric particulate composites.

Science.gov (United States)

Khanbareh, H; van der Zwaag, S; Groen, W A

2017-11-01

Composites of lead zirconate titanate particles in an epoxy matrix are prepared in the form of 0-3 and quasi 1-3 with different ceramic volume contents from 10% to 50%. Two different processing routes are tested. Firstly a conventional dielectrophoretic structuring is used to induce a chain-like particle configuration, followed by curing the matrix and poling at a high temperature and under a high voltage. Secondly a simultaneous combination of dielectrophoresis and poling is applied at room temperature while the polymer is in the liquid state followed by subsequent curing. This new processing route is practiced in an uncured thermoset system while the polymer matrix still possess a relatively high electrical conductivity. Composites with different degrees of alignment are produced by altering the magnitude of the applied electric field. A significant improvement in piezoelectric properties of quasi 1-3 composites can be achieved by a combination of dielectrophoretic alignment of the ceramic particles and poling process. It has been observed that the degree of structuring as well as the functional properties of the in-situ structured and poled composites enhance significantly compared to those of the conventionally manufactured structured composites. Improving the alignment quality enhances the piezoelectric properties of the particulate composites.

Si{sub 3}N{sub 4} layers for the in-situ passivation of GaN-based HEMT structures

Energy Technology Data Exchange (ETDEWEB)

Yunin, P. A., E-mail: yunin@ipmras.ru; Drozdov, Yu. N.; Drozdov, M. N.; Korolev, S. A.; Okhapkin, A. I.; Khrykin, O. I.; Shashkin, V. I. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2015-11-15

A method for the in situ passivation of GaN-based structures with silicon nitride in the growth chamber of a metal organic vapor phase epitaxy (MOVPE) reactor is described. The structural and electrical properties of the obtained layers are investigated. The in situ and ex situ passivation of transistor structures with silicon nitride in an electron-beam-evaporation device are compared. It is shown that ex situ passivation changes neither the initial carrier concentration nor the mobility. In situ passivation makes it possible to protect the structure surface against uncontrollable degradation upon the finishing of growth and extraction to atmosphere. In the in situ passivated structure, the carrier concentration increases and the mobility decreases. This effect should be taken into account when manufacturing passivated GaN-based transistor structures.

Enhanced functional connectivity properties of human brains during in-situ nature experience

Directory of Open Access Journals (Sweden)

Zheng Chen

2016-07-01

Full Text Available In this study, we investigated the impacts of in-situ nature and urban exposure on human brain activities and their dynamics. We randomly assigned 32 healthy right-handed college students (mean age = 20.6 years, SD = 1.6; 16 males to a 20 min in-situ sitting exposure in either a nature (n = 16 or urban environment (n = 16 and measured their Electroencephalography (EEG signals. Analyses revealed that a brief in-situ restorative nature experience may induce more efficient and stronger brain connectivity with enhanced small-world properties compared with a stressful urban experience. The enhanced small-world properties were found to be correlated with “coherent” experience measured by Perceived Restorativeness Scale (PRS. Exposure to nature also induces stronger long-term correlated activity across different brain regions with a right lateralization. These findings may advance our understanding of the functional activities during in-situ environmental exposures and imply that a nature or nature-like environment may potentially benefit cognitive processes and mental well-being.

Structural evaluation of reduced graphene oxide in graphene oxide during ion irradiation: X-ray absorption spectroscopy and in-situ sheet resistance studies

Science.gov (United States)

Saravanan, K.; Jayalakshmi, G.; Suresh, K.; Sundaravel, B.; Panigrahi, B. K.; Phase, D. M.

2018-03-01

We report the structural evolution of reduced graphene oxide (rGO) in graphene oxide (GO) flakes during 1 MeV Si+ ion irradiation. In-situ electrical resistivity measurements facilitate monitoring the sheet resistance with the increase in the fluence. The electrical sheet resistance of the GO flake shows the exponential decay behaviour with the increasing ion fluence. Raman spectra of the GO flake reveal the increase in the ID/IG ratio, indicating restoration of the sp2 network upon irradiation. The C/O ratio estimated from resonant Rutherford backscattering spectrometry analysis directly evidenced the reduction of oxygen moieties upon irradiation. C K-edge X-ray absorption near edge structure spectra reveal the restoration of C=C sp2-hybridized carbon atoms and the removal of oxygen-containing functional groups in the GO flake. STM data reveal the higher conductance in the rGO regime in comparison with the regime, where the oxygen functional groups are present. The experimental investigation demonstrates that the ion irradiation can be employed for efficient reduction of GO with tunable electrical and structural properties.

In Situ Studies of the Temperature-Dependent Surface Structure and Chemistry of Single-Crystalline (001)-Oriented La 0.8 Sr 0.2 CoO 3−δ Perovskite Thin Films

KAUST Repository

Feng, Zhenxing; Crumlin, Ethan J.; Hong, Wesley T.; Lee, Dongkyu; Mutoro, Eva; Biegalski, Michael D.; Zhou, Hua; Bluhm, Hendrik; Christen, Hans M.; Shao-Horn, Yang

2013-01-01

Perovskites are used to promote the kinetics of oxygen electrocatalysis in solid oxide fuel cells and oxygen permeation membranes. Little is known about the surface structure and chemistry of perovskites at high temperatures and partial oxygen pressures. Combining in situ X-ray reflectivity (XRR) and in situ ambient pressure X-ray photoelectron spectroscopy (APXPS), we report, for the first time, the evolution of the surface structure and chemistry of (001)-oriented perovskite La0.8Sr0.2CoO 3-δ (LSC113) and (La0.5Sr 0.5)2CoO4+δ (LSC214)-decorated LSC113 (LSC113/214) thin films as a function of temperature. Heating the (001)-oriented LSC113 surface leads to the formation of surface LSC214-like particles, which is further confirmed by ex situ Auger electron spectroscopy (AES). In contrast, the LSC113/214 surface, with activities much higher than that of LSC 113, is stable upon heating. Combined in situ XRR and APXPS measurements support that Sr enrichment may occur at the LSC113 and LSC214 interface, which can be responsible for its markedly enhanced activities. © 2013 American Chemical Society.

In Situ Studies of the Temperature-Dependent Surface Structure and Chemistry of Single-Crystalline (001)-Oriented La 0.8 Sr 0.2 CoO 3−δ Perovskite Thin Films

KAUST Repository

Feng, Zhenxing

2013-05-02

Perovskites are used to promote the kinetics of oxygen electrocatalysis in solid oxide fuel cells and oxygen permeation membranes. Little is known about the surface structure and chemistry of perovskites at high temperatures and partial oxygen pressures. Combining in situ X-ray reflectivity (XRR) and in situ ambient pressure X-ray photoelectron spectroscopy (APXPS), we report, for the first time, the evolution of the surface structure and chemistry of (001)-oriented perovskite La0.8Sr0.2CoO 3-δ (LSC113) and (La0.5Sr 0.5)2CoO4+δ (LSC214)-decorated LSC113 (LSC113/214) thin films as a function of temperature. Heating the (001)-oriented LSC113 surface leads to the formation of surface LSC214-like particles, which is further confirmed by ex situ Auger electron spectroscopy (AES). In contrast, the LSC113/214 surface, with activities much higher than that of LSC 113, is stable upon heating. Combined in situ XRR and APXPS measurements support that Sr enrichment may occur at the LSC113 and LSC214 interface, which can be responsible for its markedly enhanced activities. © 2013 American Chemical Society.

In Situ X-ray Diffraction Studies of Cathode Materials in Lithium Batteries

International Nuclear Information System (INIS)

Yang, X. Q.; Sun, X.; McBreen, J.; Mukerjee, S.; Gao, Yuan; Yakovleva, M. V.; Xing, X. K.; Daroux, M. L.

1998-01-01

There is an increasing interest in lithiated transition metal oxides because of their use as cathodes in lithium batteries. LiCoO 2 , LiNiO 2 and LiMn 2 O 4 are the three most widely used and studied materials, At present, although it is relative expensive and toxic, LiCoO 2 is the material of choice in commercial lithium ion batteries because of its ease of manufacture, better thermal stability and cycle life. However, the potential use of lithium ion batteries with larger capacity for power tools and electric vehicles in the future will demand new cathode materials with higher energy density, lower cost and better thermal stability. LiNiO 2 is isostructural with LiCoO 2 . It offers lower cost and high energy density than LiCoO 2 . However, it has much poorer thermal stability than LiCoO 2 , in the charged (delithiated) state. Co, Al, and other elements have been used to partially replace Ni in LiNiO 2 system in order to increase the thermal stability. LiMn 2 O 4 has the highest thermal stability and lowest cost and toxicity. However, the low energy density and poor cycle life at elevated temperature are the major obstacles for this material. In order to develop safer, cheaper, and better performance cathode materials, the in-depth understanding of the relationships between the thermal stability and structure, performance and structure are very important. The performance here includes energy density and cycle life of the cathode materials. X-ray diffraction (XRD) is one of the most powerful tools to study these relationships. The pioneer ex situ XRD work on cathode materials for lithium batteries was done by Ohzuku. His XRD studies on LiMn 2 O 4 , LiCoO 2 , LiNiO 2 , LiNi 0.5 Co 0.5 O 2 , and LiAl x Ni 1-x O 2 cathodes at different states of charge have provided important guidelines for the development of these new materials. However, the kinetic nature of the battery system definitely requires an in situ XRD technique to study the detail structural changes of the

Functional and structural responses to marine urbanisation

Science.gov (United States)

Mayer-Pinto, M.; Cole, V. J.; Johnston, E. L.; Bugnot, A.; Hurst, H.; Airoldi, L.; Glasby, T. M.; Dafforn, K. A.

2018-01-01

Urban areas have broad ecological footprints with complex impacts on natural systems. In coastal areas, growing populations are advancing their urban footprint into the ocean through the construction of seawalls and other built infrastructure. While we have some understanding of how urbanisation might drive functional change in terrestrial ecosystems, coastal systems have been largely overlooked. This study is one of the first to directly assess how changes in diversity relate to changes in ecosystem properties and functions (e.g. productivity, filtration rates) of artificial and natural habitats in one of the largest urbanised estuaries in the world, Sydney Harbour. We complemented our surveys with an extensive literature search. We found large and important differences in the community structure and function between artificial and natural coastal habitats. However, differences in diversity and abundance of organisms do not necessarily match observed functional changes. The abundance and composition of important functional groups differed among habitats with rocky shores having 40% and 70% more grazers than seawalls or pilings, respectively. In contrast, scavengers were approximately 8 times more abundant on seawalls than on pilings or rocky shores and algae were more diverse on natural rocky shores and seawalls than on pilings. Our results confirm previous findings in the literature. Oysters were more abundant on pilings than on rocky shores, but were also smaller. Interestingly, these differences in oyster populations did not affect in situ filtration rates between habitats. Seawalls were the most invaded habitats while pilings supported greater secondary productivity than other habitats. This study highlights the complexity of the diversity-function relationship and responses to ocean sprawl in coastal systems. Importantly, we showed that functional properties should be considered independently from structural change if we are to design and manage artificial

Properties and Structure of In Situ Transformed PAN-Based Carbon Fibers

Directory of Open Access Journals (Sweden)

Jingjing Cao

2018-06-01

Full Text Available Carbon fibers in situ prepared during the hot-pressed sintering in a vacuum is termed in situ transformed polyacrylonitrile-based (PAN-based carbon fibers, and the fibrous precursors are the pre-oxidized PAN fibers. The properties and structure of in situ transformed PAN-based carbon fibers are investigated by Nano indenter, SEM, TEM, XRD, and Raman. The results showed that the microstructure of the fiber surface layer was compact, while the core was loose, with evenly-appearing microvoids. The elastic modulus and nanohardness of the fiber surface layer (303.87 GPa and 14.82 GPa were much higher than that of the core (16.57 GPa and 1.54 GPa, and its interlayer spacing d002 and crystallinity were about 0.347 nm and 0.97 respectively. It was found that the preferred orientation of the surface carbon layers with ordered carbon atomic arrangement tended to be parallel to the fiber axis, whereas the fiber core in the amorphous region exhibited a random texture and the carbon atomic arrangement was in a disordered state. It indicates that the in situ transformed PAN-based carbon fibers possess significantly turbostratic structure and anisotropy.

Revised description of the fine structure of in situ "zooxanthellae" genus Symbiodinium.

Science.gov (United States)

Wakefield, T S; Farmer, M A; Kempf, S C

2000-08-01

The fine structure of the symbiotic dinoflagellate genus Symbiodinium has been well described. All of the published descriptions are based on tissue that was fixed in standard aldehyde and osmium fixatives and dehydrated in an ethanol series before embedding. When the technique of freeze-substitution was used to fix tissue from Cassiopeia xamachana, Aiptasia pallida, and Phyllactis flosculifera and prepare it for embedding, thecal vesicles were revealed within the in situ symbionts of all three species. Although these structures have been identified in cultured symbionts, they have never been described in the in situ symbionts. A review of the literature has revealed several instances where thecal vesicles were either overlooked or identified incorrectly. Thus the formal description of the genus Symbiodinium, which describes the in situ symbionts, contains information that is based on artifact and should be revised. A revision of the genus is suggested, and the true nature of these structures and their significance in the symbiotic association are discussed.

Effects of thermal annealing on C/FePt granular multilayers: in situ and ex situ studies

International Nuclear Information System (INIS)

Babonneau, D; Abadias, G; Toudert, J; Girardeau, T; Fonda, E; Micha, J S; Petroff, F

2008-01-01

The comprehensive study of C/FePt granular multilayers prepared by ion-beam sputtering at room temperature and subsequent annealing is reported. The as-deposited multilayers consist of carbon-encapsulated FePt nanoparticles (average size ∼3 nm) with a disordered face-centered-cubic structure. The effects of thermal annealing on the structural and magnetic properties are investigated by using dedicated ex situ and in situ techniques, including high-resolution transmission electron microscopy, extended x-ray absorption fine structure, magnetometry, and coupled grazing incidence small-angle x-ray scattering and x-ray diffraction. Our structural data show that the particle size and interparticle distance increase slightly with annealing at temperatures below 790 K by thermally activated migration of Fe and Pt atoms. We find that thermal annealing at temperatures above 870 K results in the dramatic growth of the FePt nanoparticles by coalescence and their gradual L1 0 ordering. In addition, we observe a preferential graphitization of the carbon matrix, which provides protection against oxidation for the FePt nanoparticles. Magnetization measurements indicate that progressive magnetic hardening occurs after annealing. The dependences of the blocking temperature, saturation magnetization, coercivity, and magnetocrystalline anisotropy energy on the annealing temperature are discussed on the basis of the structural data

In situ synthesis of N and Cu functionalized mesoporous FDU-14 resins and carbons for electrochemical hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Kong, AiGuo; Wang, WenJuan; Yang, Fan; Ding, HanMing; Shan, YongKui [Department of Chemistry, East China Normal University, ShangHai 200062 (China)

2010-07-15

N and Cu cooperatively functionalized mesoporous resin and carbon materials with bicontinuous cubic structure (FDU-14) were obtained by a novel synthesis method. In this method, block copolymers were used as the templates as well as the precursors for the preparation of these modifying mesoporous materials. The CuC{sub 2}O{sub 4} in the channels of mesoporous FDU-14 resins was gotten by in situ oxidation of the templates in a catalytic redox system containing Cu{sup 2+}, Al{sup 3+}, NO{sub 3}{sup -}, PO{sub 4}{sup 3-}, SO{sub 4}{sup 2-} ions. Simultaneously, the phenol-formaldehyde resin frameworks were in situ functionalized by the amine group resulting from the reduction of NO{sub 3}{sup -}, leading to the formation of N and CuC{sub 2}O{sub 4} modified mesoporous FDU-14 resin materials. Its pyrolysis at the different temperatures resulted in the production of N and Cu cooperatively functionalized mesoporous FDU-14 resin and carbon materials. The structure and composition of these materials were characterized by the X-ray power diffraction, transmission electron microscopy, N{sub 2} adsorption-desorption analysis, X-ray photoelectron spectroscopy, infrared spectroscopy, thermogravimetry analysis, and inductive coupled plasma emission spectroscopy. The electrochemical measurement indicated that N and Cu cooperatively functionalized mesoporous FDU-14 carbon materials possessed the enhanced electrochemical hydrogen storage performance. (author)

Combining in situ transmission electron microscopy irradiation experiments with cluster dynamics modeling to study nanoscale defect agglomeration in structural metals

International Nuclear Information System (INIS)

Xu Donghua; Wirth, Brian D.; Li Meimei; Kirk, Marquis A.

2012-01-01

We present a combinatorial approach that integrates state-of-the-art transmission electron microscopy (TEM) in situ irradiation experiments and high-performance computing techniques to study irradiation defect dynamics in metals. Here, we have studied the evolution of visible defect clusters in nanometer-thick molybdenum foils under 1 MeV krypton ion irradiation at 80 °C through both cluster dynamics modeling and in situ TEM experiments. The experimental details are reported elsewhere; we focus here on the details of model construction and comparing the model with the experiments. The model incorporates continuous production of point defects and/or small clusters, and the accompanying interactions, which include clustering, recombination and loss to the surfaces that result from the diffusion of the mobile defects. To account for the strong surface effect in thin TEM foils, the model includes one-dimensional spatial dependence along the foil depth, and explicitly treats the surfaces as black sinks. The rich amount of data (cluster number density and size distribution at a variety of foil thickness, irradiation dose and dose rate) offered by the advanced in situ experiments has allowed close comparisons with computer modeling and permitted significant validation and optimization of the model in terms of both physical model construct (damage production mode, identities of mobile defects) and parameterization (diffusivities of mobile defects). The optimized model exhibits good qualitative and quantitative agreement with the in situ TEM experiments. The combinatorial approach is expected to bring a unique opportunity for the study of radiation damage in structural materials.

In Situ Structure-Function Studies of Oxide Supported Rhodium Catalysts by Combined Energy Dispersive XAFS and DRIFTS Spectroscopies

International Nuclear Information System (INIS)

Evans, John; Dent, Andrew J.; Diaz-Moreno, Sofia; Fiddy, Steven G.; Jyoti, Bhrat; Tromp, Moniek; Newton, Mark A.

2007-01-01

The techniques of energy dispersive EXAFS (EDE), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and mass spectrometry (MS) have been combined to study the structure and function of an oxide supported metal catalyst, namely 5 wt% Rh/Al2O3. Using a FreLoN camera as the EDE detector and a rapid-scanning IR spectrometer, experiments could be performed with a repetition rate of 50 ms. The results show that the nature of the rhodium centers is a function of the partial pressures of the reacting gases (CO and NO) and also temperature. This combination of gases oxidizes metallic rhodium particles to Rh(CO)2 at room temperature. The proportion of the rhodium adopting this site increases as the temperature is raised (up to 450 K). Above that temperature the dicarbonyl decomposes and the metal reclusters. Once this condition is met, catalysis ensues. Gas switching techniques show that at 573 K with NO in excess, the clusters can be oxidized rapidly to afford a linear nitrosyl complex; re-exposure to CO also promotes reclustering and the CO adopts terminal (atop) and bridging (2-fold) sites

Nanoparticles of the superconductor MgB2: structural characterization and in situ study of synthesis kinetics

International Nuclear Information System (INIS)

Cui Chunxiang; Liu Debao; Shen Yutian; Sun Jinbin; Meng Fanbin; Wang Ru; Liu Shuangjin; Greer, A.L.; Chen, S.K.; Glowacki, B.A.

2004-01-01

Single-crystal MgB 2 nanoparticles, with diameters in the range 20-100 nm, have been synthesized in situ in the sample chamber of an X-ray diffractometer. The reaction kinetics are analyzed and related to the atomic-level structure of the particles as observed by high-resolution electron microscopy. Synthesis conditions may have a significant influence on microstructure and superconducting properties

Structure determination of an integral membrane protein at room temperature from crystals in situ

International Nuclear Information System (INIS)

Axford, Danny; Foadi, James; Hu, Nien-Jen; Choudhury, Hassanul Ghani; Iwata, So; Beis, Konstantinos; Evans, Gwyndaf; Alguel, Yilmaz

2015-01-01

The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samples and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines

Structure determination of an integral membrane protein at room temperature from crystals in situ

Energy Technology Data Exchange (ETDEWEB)

Axford, Danny [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Foadi, James [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Hu, Nien-Jen; Choudhury, Hassanul Ghani [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Iwata, So [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Kyoto University, Kyoto 606-8501 (Japan); Beis, Konstantinos [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Evans, Gwyndaf, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Alguel, Yilmaz, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom)

2015-05-14

The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samples and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines.

In situ surface X-ray diffraction studies of the copper-electrolyte interface. Atomic structure and homoepitaxial grwoth

Energy Technology Data Exchange (ETDEWEB)

Golks, Frederik

2011-05-19

electrolyte revealed a hexagonal, rotated adlayer structure, which was not reported before for this system. In comparison to other halide-metal(111) systems, the potential dependence of this structure suggests a strong adsorbate-adsorbate interaction. Operating under diffusion-limited conditions, i.e., at constant deposition rate, homoepitaxial growth of the Cu(001) single crystal electrode in chloride-containing solution has been investigated in situ for 1 and 5 mM Cu ion concentrations as a function of deposition overpotential. Detailed insight into the complex relationship between the atomic-scale structure of the solid-liquid interface, the growth behavior, and the resulting surface morphology was gained, revealing a pronounced mutual interaction of the Cu growth process and the Cl adlayer order. Depending on the latter, transitions from step-flow to layer-by-layer to 3D growth are observed, attributed to a reduction in the Cu surface mobility with increasing order. The kinetics of the c(2 x 2) adlayer ordering, in turn, are strongly affected during Cu deposition as compared to results obtained in Cu-free solution. Moreover, an oscillatory average strain in the surface layer is observed during layer-by-layer growth, indicating an expansion of the topmost layer occurring periodically for fractional coverages. Addition of polyethylene glycol (PEG), a commonly used inhibitor in the industrial damascene process, considerably changes the growth conditions. The chloride ordering kinetics are influenced such that the c(2 x 2) covered phase is stabilized in a widened potential regime. The onset of the transition to 3D growth is observed at more negative potentials, limiting the occurrence of layering oscillations to a narrower potential regime. Compared to the PEG-free electrolyte, the deposition rate is notably slowed down by a factor of approximately 3. The present study reports new direct experimental observations of the growth mechanisms at electrochemical interfaces on the

In situ surface X-ray diffraction studies of the copper-electrolyte interface. Atomic structure and homoepitaxial grwoth

Energy Technology Data Exchange (ETDEWEB)

Golks, Frederik

2011-05-19

hexagonal, rotated adlayer structure, which was not reported before for this system. In comparison to other halide-metal(111) systems, the potential dependence of this structure suggests a strong adsorbate-adsorbate interaction. Operating under diffusion-limited conditions, i.e., at constant deposition rate, homoepitaxial growth of the Cu(001) single crystal electrode in chloride-containing solution has been investigated in situ for 1 and 5 mM Cu ion concentrations as a function of deposition overpotential. Detailed insight into the complex relationship between the atomic-scale structure of the solid-liquid interface, the growth behavior, and the resulting surface morphology was gained, revealing a pronounced mutual interaction of the Cu growth process and the Cl adlayer order. Depending on the latter, transitions from step-flow to layer-by-layer to 3D growth are observed, attributed to a reduction in the Cu surface mobility with increasing order. The kinetics of the c(2 x 2) adlayer ordering, in turn, are strongly affected during Cu deposition as compared to results obtained in Cu-free solution. Moreover, an oscillatory average strain in the surface layer is observed during layer-by-layer growth, indicating an expansion of the topmost layer occurring periodically for fractional coverages. Addition of polyethylene glycol (PEG), a commonly used inhibitor in the industrial damascene process, considerably changes the growth conditions. The chloride ordering kinetics are influenced such that the c(2 x 2) covered phase is stabilized in a widened potential regime. The onset of the transition to 3D growth is observed at more negative potentials, limiting the occurrence of layering oscillations to a narrower potential regime. Compared to the PEG-free electrolyte, the deposition rate is notably slowed down by a factor of approximately 3. The present study reports new direct experimental observations of the growth mechanisms at electrochemical interfaces on the atomic-scale.

Structural and chemical reactivity modifications of a cobalt perovskite induced by Sr-substitution. An in situ XAS study

International Nuclear Information System (INIS)

Hueso, Jose L.; Holgado, Juan P.; Pereñíguez, Rosa; Gonzalez-DelaCruz, V.M.; Caballero, Alfonso

2015-01-01

LaCoO 3 and La 0.5 Sr 0.5 CoO 3−δ perovskites have been studied by in situ Co K-edge XAS. Although the partial substitution of La(III) by Sr(II) species induces an important increase in the catalytic oxidation activity and modifies the electronic state of the perovskite, no changes could be detected in the oxidation state of cobalt atoms. So, maintaining the electroneutrality of the perovskite requires the generation of oxygen vacancies in the network. The presence of these vacancies explains that the substituted perovskite is now much more reducible than the original LaCoO 3 perovskite. As detected by in situ XAS, after a consecutive reduction and oxidation treatment, the original crystalline structure of the LaCoO 3 perovskite is maintained, although in a more disordered state, which is not the case for the Sr doped perovskite. So, the La 0.5 Sr 0.5 CoO 3−δ perovskite submitted to the same hydrogen reduction treatment produces metallic cobalt, while as determined by in situ XAS spectroscopy the subsequent oxidation treatment yields a Co(III) oxide phase with spinel structure. Surprisingly, no Co(II) species are detected in this new spinel phase. - Highlights: • A Sr-substituted lanthanum cobalt perovskite has been prepared by spray pyrolysis. • It has been established that Co(III) cations are present in both perovskites. • LaCoO 3 is a less reducible phase than the substituted La 0.5 Sr 0.5 CoO 3−δ . • After reoxidation of reduced La 0.5 Sr 0.5 CoO 3−δ , a 100% Co(III) spinel is obtained

A multilayered supramolecular self-assembled structure from soybean oil by in situ polymerization and its applications.

Science.gov (United States)

Kavitha, Varadharajan; Gnanamani, Arumugam

2013-05-01

The present study emphasizes in situ transformation of soybean oil to self-assembled supramolecular multilayered biopolymer material. The said polymer material was characterized and the entrapment efficacy of both hydrophilic and hydrophobic moieties was studied. In brief, soybean oil at varying concentration was mixed with mineral medium and incubated under agitation (200 rpm) at 37 degrees C for 240 h. Physical observations were made till 240 h and the transformed biopolymer was separated and subjected to physical, chemical and functional characterization. The maximum size of the polymer material was measured as 2 cm in diameter and the cross sectional view displayed the multilayered onion rings like structures. SEM analysis illustrated the presence of multilayered honeycomb channeled structures. Thermal analysis demonstrated the thermal stability (200 degrees C) and high heat enthalpy (1999 J/g). Further, this multilayered assembly was able to entrap both hydrophilic and hydrophobic components simultaneously, suggesting the potential industrial application of this material.

Structural design and analysis of the multi-function waste tanks

International Nuclear Information System (INIS)

Farnworth, S.K.; Stine, M.D.; Miller, L.K.

1993-10-01

This paper describes structural design and analysis procedures to be used for the Multi-function Waste Tank Facility underground waste storage tanks proposed for the Hanford Site. The Multi-function Waste Tank Facility will consist of four one-million-gallon nominal capacity, double-shell, underground waste storage tanks and will include the associated process and control systems and aboveground structures. The tanks will consist of an inner primary steel tank and an outer secondary reinforced-concrete steel-lined tank. The primary tank head will be structurally attached to the concrete dome. A supporting layer of material will be placed between the bottom of the primary steel tank and the bottom of the steel liner on the secondary tank. The tank analysis is undertaken jointly by a team of engineers and analysts representing Kaiser Engineers Hanford, the site architect/engineer, and Westinghouse Hanford Company, the site management and operating contractor. This analysis is planned in several phases. Heat transfer solutions will address the anticipated mixing pump and cyclic fill/drain environment to provide steel and concrete temperature distributions. With this information, an in situ static analysis of the reinforced-concrete secondary tank will be carried out over the structure design life and will give material states and deformations along with strength and stability checks. Seismic analysis, accounting for soil-structure interaction and liquid loads, will be conducted with the most conservative material state, and the in situ deformations will be incorporated. Finally, penetrations and other components will be analyzed

Structural design and analysis of the multi-function waste tanks

International Nuclear Information System (INIS)

Farnworth, S.K.; Stine, M.D.; Miller, L.K.

1993-01-01

This paper describes structural design and analysis procedures to be used for the Multi-function Waste Tank Facility underground waste storage tanks proposed for the Hanford Site. The Multi-function Waste Tank Facility will consist of four one-million-gallon nominal capacity, double-shell, underground waste storage tanks and will include the associated process and control systems and aboveground structures. The tanks will consist of an inner primary steel tank and an outer secondary reinforced-concrete steel-linked tank. The primary tank head will be structurally attached to the concrete dome. A supporting layer of material will be placed between the bottom of the primary steel tank and the bottom of the steel linear on the secondary tank. The tank analysis is undertaken jointly by a team of engineers and analysts representing Kaiser Engineers Hanford, the site architect/engineer, and Westinghouse Hanford Company, the site management and operating contractor. This analysis is planned in several phases. Heat transfer solutions will address the anticipated mixing pump and cyclic fill/drain environment to provide steel and concrete temperature distributions. With this information, an in situ static analysis of the reinforced-concrete secondary tank will be carried out over the structure design life and will give material states and deformations along with strength and stability checks. Seismic analysis, accounting for soil-structure interaction and liquid loads, will be conducted with the most conservative material state, and the in situ deformations will be incorporated. Finally, penetrations and other components will be analyzed

SOFC anode reduction studied by in situ TEM

DEFF Research Database (Denmark)

Simonsen, Søren Bredmose; Wagner, Jakob Birkedal; Hansen, Thomas Willum

The Solid Oxide Fuel Cell (SOFC) is a promising part of future energy approaches due to a relatively high energy conversion efficiency and low environmental pollution. SOFCs are typically composed of ceramic materials which are highly complex at the nanoscale. TEM is routinely applied ex situ...... for studying these nanoscale structures, but only few SOFC studies have applied in situ TEM to observe the ceramic nanostructures in a reactive gas environment at elevated temperatures. The present contribution focuses on the reduction of an SOFC anode which is a necessary process to form the catalytically...... active Ni surface before operating the fuel cells. The reduction process was followed in the TEM while exposing a NiO/YSZ (YSZ = Y2O3-stabilized ZrO2) model anode to H2 at T = 250-1000⁰C. Pure NiO was used in reference experiments. Previous studies have shown that the reduction of pure Ni...

Thermal expansion behavior study of Co nanowire array with in situ x-ray diffraction and x-ray absorption fine structure techniques

Science.gov (United States)

Mo, Guang; Cai, Quan; Jiang, Longsheng; Wang, Wei; Zhang, Kunhao; Cheng, Weidong; Xing, Xueqing; Chen, Zhongjun; Wu, Zhonghua

2008-10-01

In situ x-ray diffraction and x-ray absorption fine structure techniques were used to study the structural change of ordered Co nanowire array with temperature. The results show that the Co nanowires are polycrystalline with hexagonal close packed structure without phase change up until 700 °C. A nonlinear thermal expansion behavior has been found and can be well described by a quadratic equation with the first-order thermal expansion coefficient of 4.3×10-6/°C and the second-order thermal expansion coefficient of 5.9×10-9/°C. The mechanism of this nonlinear thermal expansion behavior is discussed.

In-situ kinetics of modifications induced by swift heavy ions in Al2O3: Colour centre formation, structural modification and amorphization

International Nuclear Information System (INIS)

Grygiel, C.; Moisy, F.; Sall, M.; Lebius, H.; Balanzat, E.; Madi, T.; Been, T.; Marie, D.; Monnet, I.

2017-01-01

This paper details in-situ studies of modifications induced by swift heavy ion irradiation in α-Al2O3. This complex behaviour is intermediary between the behaviour of amorphizable and non-amorphizable materials, respectively. A unique combination of irradiation experiments was performed at the IRRSUD beam line of the GANIL facility, with three different characterisation techniques: in-situ UV–Vis absorption, in-situ grazing incidence X-Ray diffraction and ex-situ transmission electron microscopy. This allows a complete study of point defects, and by depth profile of structural and microstructural modifications created on the trajectory of the incident ion. The α-Al2O3 crystals have been irradiated by 92 MeV Xenon and 74 MeV Krypton ions, the irradiation conditions have been chosen rather similar with an energy range where the ratio between electronic and nuclear stopping power changes dramatically as function of depth penetration. The main contribution of electronic excitation, above the threshold for track formation, is present beneath the surface to finally get almost only elastic collisions at the end of the projected range. Amorphization kinetics by the overlapping of multiple ion tracks is observed. In the crystalline matrix, long range strains, unit-cell swelling, local microstrain, domain size decrease, disordering of oxygen sublattice as well as colour centre formation are found. This study highlights the relationship between ion energy losses into a material and its response. While amorphization requires electronic stopping values above a certain threshold, point defects are predominantly induced by elastic collisions, while some structural modifications of the crystalline matrix, such as unit-cell swelling, are due to contribution of both electronic and nuclear processes.

Photon structure function

International Nuclear Information System (INIS)

Bardeen, W.A.

1980-11-01

Theoretical understanding of the photon structure function is reviewed. As an illustration of the pointlike component, the parton model is briefly discussed. However, the systematic study of the photon structure function is presented through the framework of the operator product expansion. Perturbative QCD is used as the theoretical basis for the calculation of leading contributions to the operator product expansion. The influence of higher order QCD effects on these results is discussed. Recent results for the polarized structure functions are discussed

In Situ X‐Ray Diffraction Studies on Structural Changes of a P2 Layered Material during Electrochemical Desodiation/Sodiation

DEFF Research Database (Denmark)

Jung, Young Hwa; Christiansen, Ane Sælland; Johnsen, Rune E.

2015-01-01

for understanding the relationship between layered structures and electrochemical properties. A combination of in situ diffraction and ex situ X‐ray absorption spectroscopy reveals the phase transition mechanism for the ternary transition metal system (Fe–Mn–Co) with P2 stacking. In situ synchrotron X‐ray...... in a volumetric contraction of the lattice toward a fully charged state. Observations on the redox behavior of each transition metal in P2–Na0.7Fe0.4Mn0.4Co0.2O2 using X‐ray absorption spectroscopy indicate that all transition metals are involved in the reduction/oxidation process.......Sodium layered oxides with mixed transition metals have received significant attention as positive electrode candidates for sodium‐ion batteries because of their high reversible capacity. The phase transformations of layered compounds during electrochemical reactions are a pivotal feature...

An in situ USAXS-SAXS-WAXS study of precipitate size distribution evolution in a model Ni-based alloy.

Science.gov (United States)

Andrews, Ross N; Serio, Joseph; Muralidharan, Govindarajan; Ilavsky, Jan

2017-06-01

Intermetallic γ' precipitates typically strengthen nickel-based superalloys. The shape, size and spatial distribution of strengthening precipitates critically influence alloy strength, while their temporal evolution characteristics determine the high-temperature alloy stability. Combined ultra-small-, small- and wide-angle X-ray scattering (USAXS-SAXS-WAXS) analysis can be used to evaluate the temporal evolution of an alloy's precipitate size distribution (PSD) and phase structure during in situ heat treatment. Analysis of PSDs from USAXS-SAXS data employs either least-squares fitting of a preordained PSD model or a maximum entropy (MaxEnt) approach, the latter avoiding a priori definition of a functional form of the PSD. However, strong low- q scattering from grain boundaries and/or structure factor effects inhibit MaxEnt analysis of typical alloys. This work describes the extension of Bayesian-MaxEnt analysis methods to data exhibiting structure factor effects and low- q power law slopes and demonstrates their use in an in situ study of precipitate size evolution during heat treatment of a model Ni-Al-Si alloy.

In situ Raman spectroscopy studies of bulk and surface metal

NARCIS (Netherlands)

Weckhuysen, B.M.; Wachs, I.E.; Jehng, J.M.; Deo, G.; Guliants, V.V.; Benziger, J.B.

1996-01-01

Bulk V-P-O and model supported vanadia catalysts were investigated with in situ Raman spectroscopy during n-butane oxidation to maleic anhydride in order to determine the fundamental molecular structure-reactivity/selectivity insights that can be obtained from such experiments. The in situ Raman

In situ study of hydrothermal MnO2 formation

DEFF Research Database (Denmark)

Birgisson, Steinar; Shen, Yanbin; Iversen, Bo Brummerstedt

Our group has designed and successfully implemented an experimental setup capable of in situ measurements of solvothermal reactions. The setup uses synchrotron radiation and a time resolution in the range 1-10 seconds can be acquired [1]. The experiments can be optimized either to measure powder X......-ray diffraction (PXRD) data or total scattering (TS) data. From PXRD data properties such as what crystalline phases are present and their weight fractions, structural parameters (e.g. unit cell parameters, site occupancies, bond lengths), crystallite sizes and morphologies are extracted as a function of reaction...... time using Rietveld refinements [2]. TS data gives information about all the material in the solution; from complexes to amorphous particles to crystalline particles. Properties such as bond lengths, scale factors and particle sizes as a function of reaction time can be extracted via real space...

In-situ preparation of functionalized molecular sieve material and a methodology to remove template

Science.gov (United States)

Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

2016-03-01

A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, 13C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol.

In-situ preparation of functionalized molecular sieve material and a methodology to remove template.

Science.gov (United States)

Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

2016-03-10

A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, (13)C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol.

Electronic structure of low work function electrodes modified by C{sub 16}H{sub 33}SH

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyunbok [Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003 (United States); Cho, Sang Wan, E-mail: dio8027@yonsei.ac.kr [Department of Physics, Yonsei University, 1 Yonseidae-gil, Wonju-si, Gangwon-do, 220-710 (Korea, Republic of); Park, Sang Han; Cho, Mann-Ho; Yi, Yeonjin [Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemoon-Gu, Seoul, 120-749 (Korea, Republic of)

2014-10-15

Highlights: • The electronic structure of pentacene/C{sub 16}H{sub 33}SH/Au is investigated. • The work function of Au is significantly decreased with C{sub 16}H{sub 33}SH treatment. • The reduced work function is attributed to its permanent dipole moment. - Abstract: Organic and printed electronics technologies require electrodes with low work functions to facilitate the transport of electrons in and out of various optoelectronic devices. We show that the surface modifier of 1-hexadecanethiol reduces the work function of conductors using in situ ultraviolet photoemission spectroscopy, and we combine experimental and theoretical methods to investigate the origin of the work function changes. The interfacial electronic structures of pentacene/1-hexadecanethiol/Au were investigated via in situ ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy in order to understand the change in the carrier injection barrier and chemical reactions upon surface modification. Theoretical calculations using density functional theory were also performed to understand the charge distribution of 1-hexadecanethiol, which affects the reduction of the work function. The 1-hexadecanethiol surface modifier is processed in air from solution, providing an appealing alternative to chemically-reactive low-work-function metals.

Development of Additive Construction Technologies for Application to Development of Lunar/Martian Surface Structures Using In-Situ Materials

Science.gov (United States)

Werkheiser, Niki J.; Fiske, Michael R.; Edmunson, Jennifer E.; Khoshnevis, Berokh

2015-01-01

For long-duration missions on other planetary bodies, the use of in situ materials will become increasingly critical. As human presence on these bodies expands, so must the breadth of the structures required to accommodate them including habitats, laboratories, berms, radiation shielding for natural radiation and surface reactors, garages, solar storm shelters, greenhouses, etc. Planetary surface structure manufacturing and assembly technologies that incorporate in situ resources provide options for autonomous, affordable, pre-positioned environments with radiation shielding features and protection from micrometeorites, exhaust plume debris, and other hazards. The ability to use in-situ materials to construct these structures will provide a benefit in the reduction of up-mass that would otherwise make long-term Moon or Mars structures cost prohibitive. The ability to fabricate structures in situ brings with it the ability to repair these structures, which allows for the self-sufficiency and sustainability necessary for long-duration habitation. Previously, under the auspices of the MSFC In-Situ Fabrication and Repair (ISFR) project and more recently, under the jointly-managed MSFC/KSC Additive Construction with Mobile Emplacement (ACME) project, the MSFC Surface Structures Group has been developing materials and construction technologies to support future planetary habitats with in-situ resources. One such additive construction technology is known as Contour Crafting. This paper presents the results to date of these efforts, including development of novel nozzle concepts for advanced layer deposition using this process. Conceived initially for rapid development of cementitious structures on Earth, it also lends itself exceptionally well to the automated fabrication of planetary surface structures using minimally processed regolith as aggregate, and binders developed from in situ materials as well. This process has been used successfully in the fabrication of

Density functional study of molecular interactions in secondary structures of proteins.

Science.gov (United States)

Takano, Yu; Kusaka, Ayumi; Nakamura, Haruki

2016-01-01

Proteins play diverse and vital roles in biology, which are dominated by their three-dimensional structures. The three-dimensional structure of a protein determines its functions and chemical properties. Protein secondary structures, including α-helices and β-sheets, are key components of the protein architecture. Molecular interactions, in particular hydrogen bonds, play significant roles in the formation of protein secondary structures. Precise and quantitative estimations of these interactions are required to understand the principles underlying the formation of three-dimensional protein structures. In the present study, we have investigated the molecular interactions in α-helices and β-sheets, using ab initio wave function-based methods, the Hartree-Fock method (HF) and the second-order Møller-Plesset perturbation theory (MP2), density functional theory, and molecular mechanics. The characteristic interactions essential for forming the secondary structures are discussed quantitatively.

Real time nanoscale structural evaluation of gold structures on Si (100) surface using in-situ transmission electron microscopy

International Nuclear Information System (INIS)

Rath, A.; Juluri, R. R.; Satyam, P. V.

2014-01-01

Transport behavior of gold nanostructures on Si(100) substrate during annealing under high vacuum has been investigated using in-situ real time transmission electron microscopy (TEM). A comparative study has been done on the morphological changes due to annealing under different vacuum environments. Au thin films of thickness ∼2.0 nm were deposited on native oxide covered silicon substrate by using thermal evaporation system. In-situ real time TEM measurements at 850 °C showed the isotropic growth of rectangular/square shaped gold-silicon alloy structures. During the growth, it is observed that the alloying occurs in liquid phase followed by transformation into the rectangular shapes. For similar system, ex-situ annealing in low vacuum (10 −2 millibars) at 850 °C showed the spherical gold nanostructures with no Au-Si alloy formation. Under low vacuum annealing conditions, the rate of formation of the oxide layer dominates the oxide desorption rate, resulting in the creation of a barrier layer between Au and Si, which restricts the inter diffusion of Au in to Si. This work demonstrates the important role of interfacial oxide layer on the growth of nanoscale Au-Si alloy structures during the initial growth. The time dependent TEM images are presented to offer a direct insight into the fundamental dynamics of the sintering process at the nanoscale

Dry Sliding Wear Behavior of A356 Alloy/Mg2Sip Functionally Graded in-situ Composites: Effect of Processing Conditions

Directory of Open Access Journals (Sweden)

S.C. Ram

2016-09-01

Full Text Available In present study, the effect of dry sliding wear conditions of A356 alloy/Mg2Sip functionally graded in-situ composites developed by centrifugal casting method has been studied. A pure commercial A356 alloy (Al–7.5Si–0.3Mg was selected to be the matrix of the composites and primary Mg2Sip reinforcing particles were formed by in-situ chemical reaction with an average grain size of 40-47.8 µm. The Al–(Mg2Sip functionally graded metal matrix composites (FGMMC’s were synthesized by centrifugal casting technique with radial geometry, using two different mould rotating speeds ( 1200 and 1600 rpm. The X-ray diffraction (XRD characterization technique was carried out to confirm the in-situ formed Mg2Si particles in composites. Optical microscopy examination was carried out to reveals the grain refinement of Al-rich grains due to in-situ formed Mg2Si particles. Scanning electron microscope (SEM and Energy dispersive X-ray spectroscopy (EDS techniques were carried out to reveal the distribution of phases, morphological characteristics and confirmation of primary Mg2Si particles in the matrix. The sliding wear behavior was studied using a Pin-on-Disc set-up machine with sliding wear parameters: effect of loads (N, effect of sliding distances (m and effect of Mg on wear at room temperature with a high-carbon chromium steel disc (HRC-64 as counter surfaces. A good correlation was evidenced between the dry sliding behaviour of functionally graded in-situ composites and the distribution of Mg2Si reinforcing particles. Beside the above processing conditions, the dominant wear mechanisms of functionally graded in-situ composites have been correlated with the microstructures. The hardness and wear resistance properties of these composites increase with increasing volume percent of reinforced primary Si/Mg2Si particles toward inner zone of cast cylindrical shapes. The objective of this works was to study the tribological characteristics under dry sliding

Dynamical properties of nano-structured catalysts for methane conversion: an in situ scattering study

DEFF Research Database (Denmark)

Kehres, Jan

/NiO particles in a fresh catalyst sample showed a Ni/NiO core shell structure. The Ni lattice parameter decreased during the reduction due to the release of stress between the Ni core and the NiO shell. Ni particles sintered during heating in hydrogen after the reduction of the NiO shell. Dry reforming......The reactivity of catalyst particles can be radically enhanced by decreasing their size down to the nanometer range. The nanostructure of a catalyst can have an enormous and positive influence on the reaction rate, for example strong structure sensitivity was observed for methane reforming...... range from 298 - 1023 K. Correlated crystallite and particle growth due to sintering were observed after the decomposition of the surfactant. Furthermore transformations from rod to spherical particle shape were observed. In situ reduction experiments of a Ni/MgAl2O4 catalyst were performed. The Ni...

Advanced In Situ I-V Measurements Used in the Study of Porous Structures Growth on Silicon

Directory of Open Access Journals (Sweden)

Amare Benor

2017-01-01

Full Text Available The rate of oxide formation during growth of pores structures on silicon was investigated by in situ I-V measurements. The measurements were designed to get two I-V curves in a short time (total time for the two measurements was 300 seconds taking into account the gap (in mA/cm2 for each corresponding voltage. The in situ I-V measurements were made at different pore depth/time, at the electrolyte-pore tip interface, while etching takes place based on p-type Si. The results showed increasing, decreasing, and constant I-V gap in time, for macropores, nanopores, and electropolishing regimes, respectively. This was related to the expected diffusion limitation of oxide forming (H2O molecules reaching the electrolyte-pore tip and the anodizing current, while etching takes place. The method can be developed further and has the potential to be applied in other electrochemically etched porous semiconductor materials.

New Pyrazole-Hydrazone Derivatives: X-ray Analysis, Molecular Structure Investigation via Density Functional Theory (DFT) and Their High In-Situ Catecholase Activity.

Science.gov (United States)

Karrouchi, Khalid; Yousfi, El Bekkaye; Sebbar, Nada Kheira; Ramli, Youssef; Taoufik, Jamal; Ouzidan, Younes; Ansar, M'hammed; Mabkhot, Yahia N; Ghabbour, Hazem A; Radi, Smaail

2017-10-25

The development of low-cost catalytic systems that mimic the activity of tyrosinase enzymes (Catechol oxidase) is of great promise for future biochemistry technologic demands. Herein, we report the synthesis of new biomolecules systems based on hydrazone derivatives containing a pyrazole moiety ( L1 - L6 ) with superior catecholase activity. Crystal structures of L1 and L2 biomolecules were determined by X-ray single crystal diffraction (XRD). Optimized geometrical parameters were calculated by density functional theory (DFT) at B3LYP/6-31G (d, p) level and were found to be in good agreement with single crystal XRD data. Copper (II) complexes of the compounds ( L1 - L6 ), generated in-situ, were investigated for their catalytic activities towards the oxidation reaction of catechol to ortho -quinone with the atmospheric dioxygen, in an attempt to model the activity of the copper containing enzyme tyrosinase. The studies showed that the activities depend on four parameters: the nature of the ligand, the nature of counter anion, the nature of solvent and the concentration of ligand. The Cu(II)-ligands, given here, present the highest catalytic activity (72.920 μmol·L -1 ·min -1 ) among the catalysts recently reported in the existing literature.

Thermal analysis of in-situ curing for thermoset, hoop-wound structures using infrared heating: Part II. Dependent scattering effect

International Nuclear Information System (INIS)

Chern, B.C.; Moon, T.J.; Howell, J.R.

1995-01-01

The volume fraction of the fibers present in commercial filament wound structures, formed from either epoxy-impregnated tapes (open-quotes prepregclose quotes) or fiber strands pulled through an epoxy bath, approaches 60 percent. Such close-packed structures are near the region that may cause dependent scattering effects to be important; that is, the scattering characteristics of one fiber may be affected by the presence of nearby fibers. This dependent scattering may change the single-fiber extinction coefficient and phase function, and thus may change the radiative transfer in such materials. This effect is studied for unidirectional fibers dispersed in a matrix with nonunity refractive index, and with large size parameter (fiber diameter to wavelength ratio) typical of commercial fiber-matrix composites. Only the case of radiation incident normal to the cylinder axes is considered, as this maximizes the dependent effects. The dependent extinction efficiency is found by solving the dispersion relations for the complex effective propagation constant of the composites. An estimation of this dependent scattering effect on the infrared in-situ curing of thermoset-hoop-wound structures is also conducted. It is found that the wave interference effect is significant for S-glass/3501-6 composite, and neglect of this effect tends to overestimate the temperature and cure state within the materials during IR in-situ curing. 23 refs., 8 figs

Structural Investigation of Sodium Layered Oxides Via in Situ Synchrotron X-Ray Diffraction

DEFF Research Database (Denmark)

Jung, Young Hwa; Christiansen, Ane Sælland; Johnsen, Rune

2015-01-01

electrochemical reaction is generally considered to be a pivotal feature for understanding the relationship between layered structures and electrochemical properties. Here the structure, phase stability, and electrochemical properties of two kinds of layered oxides, P2 and O3, are investigated through in......-situ synchrotron XRD experiments. A capillary Na-based cell is designed to minimize interference in other substances such as a separator or external battery parts. This approach could give us to obtain clear diffraction patterns with high intensity during electrochemical reaction in a short period of time without...... further relaxation step. We carefully scrutinized reversible structural phase transformations during electrochemical reaction of P2 and O3-layered compounds based on in situ analysis, and detailed results will be discussed....

Structure observation of single solidified droplet by in situ controllable quenching based on nanocalorimetry

International Nuclear Information System (INIS)

Zhao, Bingge; Li, Linfang; Yang, Bin; Yan, Ming; Zhai, Qijie; Gao, Yulai

2013-01-01

Highlights: •Controllable quenching rate up to 15,000 K/s was realized by FSC. •FSC sample was novelly characterized by FIB and HRTEM. •Solidification structure with undercooling of 110.9 K was investigated. •This study opens a new approach in rapid solidification and FSC measurement. -- Abstract: Fast scanning calorimetry (FSC) based on nanocalorimetry and thin film technique is a newly developed attractive tool to investigate the solidification behavior of single droplet by in situ controllable ultrafast cooling. In this paper, we introduced this novel technique to in situ control the quenching of single Sn3.5Ag metallic droplet at cooling rate up to 15,000 K/s with corresponding undercooling of 110.9 K. In particular, the solidification structure of this real time quenched single droplet was observed and analyzed with focused ion beam (FIB), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). This research proposed a new approach to research the solidification structure of single droplet with precisely controlled size and extreme cooling rate

In Situ Guided Wave Structural Health Monitoring System

Science.gov (United States)

Zhao, George; Tittmann, Bernhard R.

2011-01-01

Aircraft engine rotating equipment operates at high temperatures and stresses. Noninvasive inspection of microcracks in those components poses a challenge for nondestructive evaluation. A low-cost, low-profile, high-temperature ultrasonic guided wave sensor was developed that detects cracks in situ. The transducer design provides nondestructive evaluation of structures and materials. A key feature of the sensor is that it withstands high temperatures and excites strong surface wave energy to inspect surface and subsurface cracks. The sol-gel bismuth titanate-based surface acoustic wave (SAW) sensor can generate efficient SAWs for crack inspection. The sensor is very thin (submillimeter) and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. The sensor can be implemented on structures of various shapes. With a spray-coating process, the sensor can be applied to the surface of large curvatures. It has minimal effect on airflow or rotating equipment imbalance, and provides good sensitivity.

Calcium exchange, structure, and function in cultured adult myocardial cells

International Nuclear Information System (INIS)

Langer, G.A.; Frank, J.S.; Rich, T.L.; Orner, F.B.

1987-01-01

Cells digested from adult rat heart and cultured for 14 days demonstrate all the structural elements, in mature form, associated with the process of excitation-contraction (EC) coupling. The transverse tubular (TT) system is well developed with an extensive junctional sarcoplasmic reticulum (JSR). In nonphosphate-containing buffer contraction of the cells is lost as rapidly as zero extracellular Ca concentration ([Ca] 0 ) solution is applied and a negative contraction staircase is produced on increase of stimulation frequency. Structurally and functionally the cells have the characteristics of adult cells in situ. 45 Ca exchange and total 45 Ca measurement in N-2-hydroxyethylpiperazine N'-2-ethanesulfonic acid (HEPES)-buffered perfusate define three components of cellular Ca: 1) a rapidly exchangeable component accounting for 36% of total Ca, 2) a slowly exchangeable component (t/sub 1/2/ 53 min) accounting for 7% total Ca, and 3) the remaining 57% cellular Ca is inexchangeable (demonstrates no significant exchange within 60 min). The slowly exchangeable component can be increased 10-fold within 60 min by addition of phosphate to the perfusate. The Ca distribution and exchange characteristics are little different from those of 3-day cultures of neonatal rat heart previously studied. The results suggest that the cells are representative of adult cells in situ and that both sarcolemmal-bound and sarcoplasmic reticular Ca contribute to the component of Ca that is rapidly exchangeable

Towards functionalization of graphene: in situ study of the nucleation of copper-phtalocyanine on graphene

Science.gov (United States)

Schwarz, Daniel; Henneke, Caroline; Kumpf, Christian

2016-02-01

Molecular films present an elegant way for the uniform functionalization or doping of graphene. Here, we present an in situ study on the initial growth of copper phthalocyanine (CuPc) on epitaxial graphene on Ir(111). We followed the growth up to a closed monolayer with low energy electron microscopy and selected area electron diffraction (μLEED). The molecules coexist on graphene in a disordered phase without long-range order and an ordered crystalline phase. The local topography of the graphene substrate plays an important role in the nucleation process of the crystalline phase. Graphene flakes on Ir(111) feature regions that are under more tensile stress than others. We observe that the CuPc molecules form ordered domains initially on those graphene regions that are closest to the fully relaxed lattice. We attribute this effect to a stronger influence of the underlying Ir(111) substrate for molecules adsorbed on those relaxed regions.

Towards functionalization of graphene: in situ study of the nucleation of copper-phtalocyanine on graphene

International Nuclear Information System (INIS)

Schwarz, Daniel; Henneke, Caroline; Kumpf, Christian

2016-01-01

Molecular films present an elegant way for the uniform functionalization or doping of graphene. Here, we present an in situ study on the initial growth of copper phthalocyanine (CuPc) on epitaxial graphene on Ir(111). We followed the growth up to a closed monolayer with low energy electron microscopy and selected area electron diffraction (μLEED). The molecules coexist on graphene in a disordered phase without long-range order and an ordered crystalline phase. The local topography of the graphene substrate plays an important role in the nucleation process of the crystalline phase. Graphene flakes on Ir(111) feature regions that are under more tensile stress than others. We observe that the CuPc molecules form ordered domains initially on those graphene regions that are closest to the fully relaxed lattice. We attribute this effect to a stronger influence of the underlying Ir(111) substrate for molecules adsorbed on those relaxed regions. (paper)

Nanoparticle Metamorphosis: An in Situ High-Temperature Transmission Electron Microscopy Study of the Structural Evolution of Heterogeneous Au:Fe 2 O 3 Nanoparticles

KAUST Repository

Baumgardner, William J.

2014-05-27

High-temperature in situ electron microscopy and X-ray diffraction have revealed that Au and Fe2O3 particles fuse in a fluid fashion at temperatures far below their size-reduced melting points. With increasing temperature, the fused particles undergo a sequence of complex structural transformations from surface alloy to phase segregated and ultimately core-shell structures. The combination of in situ electron microscopy and spectroscopy provides insights into fundamental thermodynamic and kinetic aspects governing the formation of heterogeneous nanostructures. The observed structural transformations present an interesting analogy to thin film growth on the curved surface of a nanoparticle. Using single-particle observations, we constructed a phase diagram illustrating the complex relationships among composition, morphology, temperature, and particle size. © 2014 American Chemical Society.

Nanoparticle Metamorphosis: An in Situ High-Temperature Transmission Electron Microscopy Study of the Structural Evolution of Heterogeneous Au:Fe 2 O 3 Nanoparticles

KAUST Repository

Baumgardner, William J.; Yu, Yingchao; Hovden, Robert; Honrao, Shreyas; Hennig, Richard G.; Abruñ a, Hé ctor D.; Muller, David; Hanrath, Tobias

2014-01-01

High-temperature in situ electron microscopy and X-ray diffraction have revealed that Au and Fe2O3 particles fuse in a fluid fashion at temperatures far below their size-reduced melting points. With increasing temperature, the fused particles undergo a sequence of complex structural transformations from surface alloy to phase segregated and ultimately core-shell structures. The combination of in situ electron microscopy and spectroscopy provides insights into fundamental thermodynamic and kinetic aspects governing the formation of heterogeneous nanostructures. The observed structural transformations present an interesting analogy to thin film growth on the curved surface of a nanoparticle. Using single-particle observations, we constructed a phase diagram illustrating the complex relationships among composition, morphology, temperature, and particle size. © 2014 American Chemical Society.

In-situ synchrotron PXRD study of spinel LiMn2O4 formation

DEFF Research Database (Denmark)

Birgisson, Steinar; Jensen, Kirsten Marie Ørnsbjerg; Christiansen, Troels Lindahl

structural properties for the reaction being studied. Normally the reactions are started by heating and a constant temperature is kept throughout the experiment. In this study the hydrothermal reaction previously shown to produce spinel LiMn2O4 nanoparticles is studied in-situ to learn more about the phase......O4, depending on the initial concentration if Li-ions. An impurity phase, identified as Mn3O4, is also detected in different concentrations depending on reaction time and temperature. We have developed an experimental technique for in-situ measurements of solvothermal reactions under sub...... in the in-situ measurements it gives a unique opportunity to study reaction kinetics and thermodynamic quantities of the reactions. A temperature study of the reaction has been conducted to see how the formation rate and particle growth is affected by temperature while the precursor concentration is kept...

Irradiation-related amorphization and crystallization: In situ transmission electron microscope studies

International Nuclear Information System (INIS)

Allen, C.W.

1994-01-01

Interfacing an ion accelerator to a transmission electron microscope (TEM) allows the analytical functions of TEM imaging and diffraction to be employed during ion-irradiation effects studies. At present there are twelve such installations in Japan, one in France and one in the US. This paper treats several aspects of in situ studies involving electron and ion beam induced and enhanced phase transformations and presents results of several in situ experiments to illustrate the dynamics of this approach in the materials science of irradiation effects. The paper describes the ion- and electron-induced amorphization of CuTi; the ion-irradiation-enhanced transformation of TiCr 2 ; and the ion- and electron-irradiation-enhanced crystallization of CoSi 2

Simulation of salt behavior using in situ response

International Nuclear Information System (INIS)

Li, W.T.

1986-01-01

The time-dependent nonlinear structural behavior in a salt formation around the openings can be obtained by either performing computational analysis of measuring in situ responses. However, analysis using laboratory test data may often deviate from the actual in situ conditions and geomechanical instruments can provide information only up to the time when the measurements were taken. A method has been suggested for simulating the salt behavior by utilizing the steady-state portion of in situ response history. Governing equations for computational analysis were normalized to the creep constant, the equations were solved, and the analytical response history was then computed in terms of normalized time. By synchronizing the response history obtained from the analysis to the one measured at the site, the creep constant was determined. Then the structural response of the salt was computed. This paper presents an improved method for simulating the salt behavior. In this method, the governing equations are normalized to the creep function, which represents the transient and the steady-state creep behavior. Both the transient and the steady-state portions of in situ response history are used in determining the creep function. Finally, a nonlinear mapping process relating the normalized and real time domains determines the behavior of the salt

Rheological studies of creams. I. Rheological functions and structure of creams.

Science.gov (United States)

Erös, I; Thaleb, A

1994-05-01

Large number of washable (o/w type) creams were prepared for rheological investigation. The rheological functions known from the literature were determined in our studies. Rheological constants were determined by measurements and calculations. From these, we selected those ones which were applicable to characterize the energy status of the coherent structure and which gave the most information for practical work, elaboration of composition and evaluation of stability. These functions and parameters are the following: flow curves, viscosity vs shear time and viscosity vs temperature functions, Bingham-type yield value, plastic viscosity, structure breakdown rate constant, activation energy.

A light-assisted in situ embedment of silver nanoparticles to prepare functionalized fabrics

Directory of Open Access Journals (Sweden)

Toh HS

2017-11-01

Full Text Available Her Shuang Toh,1 Roxanne Line Faure,2 Liyana Bte Mohd Amin,1 Crystal Yu Fang Hay,1 Saji George1,3 1Centre of Sustainable Nanotechnology, School of Chemical and Life Sciences, Nanyang Polytechnic, Singapore, Singapore; 2DUT Analyses Biologiques et Biochimiques, IUT Génie Biologique, Dijon, France; 3Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Sainte-Anne-de-Bellevue, QC, Canada Abstract: This article presents a simple, one-step, in situ generation of silver nanoparticle-functionalized fabrics with antibacterial properties, circumventing the conventional, multistep, time-consuming methods. Silver nanoparticle formation was studied with a library of capping agents (branched polyethylenimine [BPEI] of molecular weight [Mw] 10,000 and 25,000, polyvinylpyrrolidone, polyethylene glycol, polyvinylalcohol and citrate mixed with silver nitrate. The mixture was then exposed to an assortment of light wavelengths (ultraviolet, infrared and simulated solar light for studying the light-assisted synthesis of nanoparticles. The formation of nanoparticles corresponded with the reducing capabilities of the polymers wherein BPEI gave the best response. Notably, the irradiation wavelengths had little effect on the formation of the nanoparticle when the total irradiation energy was kept constant. The feasibility of utilizing this method for in situ nanoparticle synthesis on textile fabrics (towel [100% cotton], gauze [100% cotton], rayon, felt [100% polyester] and microfiber [15% nylon, 85% polyester] was verified by exposing the fabrics soaked in an aqueous solution of 1% (w/v AgNO3 and 1% (w/v BPEI (Mw 25,000 to light. The formation of nanoparticles on fabrics and their retention after washing was verified using scanning electron microscopy and quantified by inductively coupled plasma optical emission spectrometry. The functional property of the fabric as an antibacterial surface was successfully demonstrated using

Chemoselective Reduction and Alkylation of Carbonyl Functions Using Phosphonium Salts as an in Situ Protecting Groups.

Science.gov (United States)

Ohta, Reiya; Fujioka, Hiromichi

2017-01-01

Recent progress in the chemoselective reduction and alkylation of carbonyl functions using our in situ protection method is described. Methods that enable reversal or control of the reactivity of a carbonyl functional group are potentially useful. They open up new areas of synthetic organic chemistry and change the concept of retrosynthesis because they remove the need for complicated protection/deprotection sequences. In this account, we discuss the strategy and applications of our in situ protection method using phosphonium salts.

Density functional theory studies of screw dislocation core structures in bcc metals

DEFF Research Database (Denmark)

Frederiksen, Søren Lund; Jacobsen, Karsten Wedel

2003-01-01

The core structures of (I 11) screw dislocations in bee metals are studied using density functional theory in the local-density approximation. For Mo and Fe, direct calculations of the core structures show the cores to be symmetric with respect to 180degrees rotations around an axis perpendicular...... to symmetric core structures for all the studied metals....

Phenomenological study of the nucleon structure functions; Etude phenomenologique des fonctions de structure du nucleon

Energy Technology Data Exchange (ETDEWEB)

Bertini, M

1995-05-12

This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F{sub 2}) and polarized (g{sub 1}) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F{sub 2} and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions g{sup p,n,d} and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends.

Differentiating between bipolar and unipolar depression in functional and structural MRI studies.

Science.gov (United States)

Han, Kyu-Man; De Berardis, Domenico; Fornaro, Michele; Kim, Yong-Ku

2018-03-28

Distinguishing depression in bipolar disorder (BD) from unipolar depression (UD) solely based on clinical clues is difficult, which has led to the exploration of promising neural markers in neuroimaging measures for discriminating between BD depression and UD. In this article, we review structural and functional magnetic resonance imaging (MRI) studies that directly compare UD and BD depression based on neuroimaging modalities including functional MRI studies on regional brain activation or functional connectivity, structural MRI on gray or white matter morphology, and pattern classification analyses using a machine learning approach. Numerous studies have reported distinct functional and structural alterations in emotion- or reward-processing neural circuits between BD depression and UD. Different activation patterns in neural networks including the amygdala, anterior cingulate cortex (ACC), prefrontal cortex (PFC), and striatum during emotion-, reward-, or cognition-related tasks have been reported between BD and UD. A stronger functional connectivity pattern in BD was pronounced in default mode and in frontoparietal networks and brain regions including the PFC, ACC, parietal and temporal regions, and thalamus compared to UD. Gray matter volume differences in the ACC, hippocampus, amygdala, and dorsolateral prefrontal cortex (DLPFC) have been reported between BD and UD, along with a thinner DLPFC in BD compared to UD. BD showed reduced integrity in the anterior part of the corpus callosum and posterior cingulum compared to UD. Several studies performed pattern classification analysis using structural and functional MRI data to distinguish between UD and BD depression using a supervised machine learning approach, which yielded a moderate level of accuracy in classification. Copyright © 2018 Elsevier Inc. All rights reserved.

In situ neutron diffraction studies of high density amorphous ice under pressure

International Nuclear Information System (INIS)

Klotz, Stefan; Straessle, Th; Saitta, A M; Rousse, G; Hamel, G; Nelmes, R J; Loveday, J S; Guthrie, M

2005-01-01

We review recent in situ neutron diffraction studies on the structural pressure dependence and the recrystallization of dense amorphous ices up to 2 GPa. Progress in high pressure techniques and data analysis methods allows the reliable determination of all three partial structure factors of amorphous ice under pressure. The strong pressure dependence of the g OO (r) correlation function shows that the isothermal compression of high density amorphous ice (HDA) at 100 K is achieved by a contraction (∼ 20%) of the second-neighbour coordination shell leading to a strong increase in coordination. The g DD (r) and g OD (r) structure factors are, in contrast, only weakly sensitive to pressure. These data allow a comparison with structural features of the recently reported 'very high density amorphous ice' (VHDA) which indicates that VHDA at ambient pressure is very similar to compressed HDA, at least up to the second-neighbour shell. The recrystallization of HDA has been investigated in the range 0.3-2 GPa. It is shown that hydrogen-disordered phases are produced which normally grow only from the liquid, such as ice XII, and in particular ice IV. These findings are in good agreement with results on quench-recovered samples

A multi-functional guanine derivative for studying the DNA G-quadruplex structure.

Science.gov (United States)

Ishizuka, Takumi; Zhao, Pei-Yan; Bao, Hong-Liang; Xu, Yan

2017-10-23

In the present study, we developed a multi-functional guanine derivative, 8F G, as a G-quadruplex stabilizer, a fluorescent probe for the detection of G-quadruplex formation, and a 19 F sensor for the observation of the G-quadruplex. We demonstrate that the functional nucleoside bearing a 3,5-bis(trifluoromethyl)benzene group at the 8-position of guanine stabilizes the DNA G-quadruplex structure and fluoresces following the G-quadruplex formation. Furthermore, we show that the functional sensor can be used to directly observe DNA G-quadruplexes by 19 F-NMR in living cells. To our knowledge, this is the first study showing that the nucleoside derivative simultaneously allows for three kinds of functions at a single G-quadruplex DNA. Our results suggest that the multi-functional nucleoside derivative can be broadly used for studying the G-quadruplex structure and serves as a powerful tool for examining the molecular basis of G-quadruplex formation in vitro and in living cells.

Introgression from cultivated rice alters genetic structures of wild relative populations: implications for in situ conservation

Science.gov (United States)

Jin, Xin; Chen, Yu; Liu, Ping; Li, Chen; Cai, Xingxing; Rong, Jun

2018-01-01

Abstract Maintaining genetic integrity is essential for in situ and ex situ conservation of crop wild relative (CWR) species. However, introgression of crop alleles into CWR species/populations may change their genetic structure and diversity, resulting in more invasive weeds or, in contrast, the extinction of endangered populations. To determine crop-wild introgression and its consequences, we examined the genetic structure and diversity of six wild rice (Oryza rufipogon) populations under in situ conservation in China. Thirty-four simple sequence repeat (SSR) and 34 insertion/deletion markers were used to genotype the wild rice populations and two sets of rice cultivars (O. sativa), corresponding to the two types of molecular markers. Shared alleles and STRUCTURE analyses suggested a variable level of crop-wild introgression and admixture. Principal coordinates and cluster analyses indicated differentiation of wild rice populations, which was associated with the spatial distances to cultivated rice fields. The level of overall genetic diversity was comparable between wild rice populations and rice cultivars, but a great number of wild-specific alleles was detected in the wild populations. We conclude based on the results that crop-wild introgression can considerably alter the pattern of genetic structure and relationships of CWR populations. Appropriate measures should be taken for effective in situ conservation of CWR species under the scenario of crop-wild introgression. PMID:29308123

In-situ EC-STM studies on the influence of halide anions on structure and reactivity of dibenzylviologen on Cu(100)

Energy Technology Data Exchange (ETDEWEB)

Gentz, Knud; Wandelt, Klaus [Institute of Physical and Theoretical Chemistry, Bonn University (Germany); Broekmann, Peter [University of Bern (Switzerland)

2009-07-01

Copper has become a focus of research activities over the last two decades due to its use as interconnect material in microchip design. Nitrogen-containing cationic organic molecules have been studied as additives for the so-called copper damascene process. In the present investigation the structures and reactivity of a dibenzylviologen (DBV) layer adsorbed on a bromide-modified Cu(100) surface have been studied by in-situ electrochemical STM and will be compared to the results on the chloride-modified substrate and the related Diphenylviologen (DPV). N,N'-dibenzyl-4,4'-bipyridinium molecules (dibenzylviologen, DBV) spontaneously adsorb on a halide-modified Cu(100)-surface, forming distinctive patterns, which have been characterized by in-situ scanning tunneling microscopy. Depending on the adsorption potential a striped phase, a cavitand phase and an amorphous phase have been identified. Cyclic voltammetry indicates that even more processes take place on the surface, because if the potential is decreased beyond a range of fully reversible processes, an irreversible surface phase formation is observed at -450 mV vs. RHE. This surface phase passivates the surface against adsorption of the dicationic phase, so the charge reversal of the interface in the outer Helmholtz layer seems to be reduced.

Prion structure investigated in situ, ex vivo, and in vitro by FTIR spectroscopy

Science.gov (United States)

Kneipp, Janina; Miller, Lisa M.; Spassov, Sashko; Sokolowski, Fabian; Lasch, Peter; Beekes, Michael; Naumann, Dieter

2004-07-01

Syrian hamster nervous tissue was investigated by FTIR microspectroscopy with conventional and synchrotron infrared light sources. Various tissue structures from the cerebellum and medulla oblongata of scrapie-infected and control hamsters were investigated at a spatial resolution of 50 μm. Single neurons in dorsal root ganglia of scrapie-infected hamsters were analyzed by raster scan mapping at 6 μm spatial resolution. These measurements enabled us to (i) scrutinize structural differences between infected and non-infected tissue and (ii) analyze for the first time the distribution of different protein structures in situ within single nerve cells. Single nerve cells exhibited areas of increased β-sheet content, which co-localized consistently with accumulations of the pathological prion protein (PrPSc). Spectral data were also obtained from purified, partly proteinase K digested PrPSc isolated from scrapie-infected nervous tissue of hamsters to elucidate similarities/dissimilarities between prion structure in situ and ex vivo. A further comparison is drawn to the recombinant Syrian hamster prion protein SHaPrP90-232, whose in vitro transition from the predominantly a-helical isoform to β-sheet rich oligomeric structures was also investigated by FTIR spectroscopy.

[Study of the phase transformation of TiO2 with in-situ XRD in different gas].

Science.gov (United States)

Ma, Li-Jing; Guo, Lie-Jin

2011-04-01

TiO2 sample was prepared by sol-gel method from chloride titanium. The phase transformation of the prepared TiO2 sample was studied by in-situ XRD and normal XRD in different gas. The experimental results showed that the phase transformation temperatures of TiO2 were different under in-situ or normal XRD in different kinds of gas. The transformation of amorphous TiO2 to anatase was controlled by kinetics before 500 degrees C. In-situ XRD showed that the growth of anatase was inhibited, but the transformation of anatase to rutile was accelerated under inactive nitrogen in contrast to air. Also better crystal was obtained under hydrogen than in argon. These all showed that external oxygen might accelerate the growth of TiO2, but reduced gas might partly counteract the negative influence of lack of external oxygen. The mechanism of phase transformation of TiO2 was studied by in-situ XRD in order to control the structure in situ.

[Neutron scatter studies of chromatin structure related to function

International Nuclear Information System (INIS)

Bradbury, E.M.

1990-01-01

This study is concerned with the application of neutron scatter techniques to the different structural states of nucleosomes and chromatin with the long term objective of understanding how the enormous lengths of DNA are folded into chromosomes. Micrococcal nuclease digestion kinetics have defined two subnucleosome particles; the chromatosome with 168 bp DNA, the histone octamer and one H1 and the nucleosome core particle with 146 bp DNA and the histone octamer. As will be discussed, the structure of the 146 bp DNA core particle is known in solution at low resolution from neutron scatter studies and in crystals. Based on this structure, the authors have a working model for the chromatosome and the mode of binding of H1. In order to define the structure of the nucleosome and also the different orders of chromatin structures they need to know the paths of DNA that link nucleosomes and the factors associated with chromosome functions that act on those DNA paths. The major region for this situation is the inherent variabilities in nucleosome DNA sequences, in the histone subtypes and their states of chemical modification and in the precise locations of nucleosomes. Such variabilities obscure the underlying principles that govern the packaging of DNA into the different structural states of nucleosomes and chromatin. The only way to elucidate these principles is to study the structures of nucleosomes and oligonucleosomes that are fully defined. They have largely achieved these objectives

A propagation tool to connect remote-sensing observations with in-situ measurements of heliospheric structures

Science.gov (United States)

Rouillard, A. P.; Lavraud, B.; Génot, V.; Bouchemit, M.; Dufourg, N.; Plotnikov, I.; Pinto, R. F.; Sanchez-Diaz, E.; Lavarra, M.; Penou, M.; Jacquey, C.; André, N.; Caussarieu, S.; Toniutti, J.-P.; Popescu, D.; Buchlin, E.; Caminade, S.; Alingery, P.; Davies, J. A.; Odstrcil, D.; Mays, L.

2017-11-01

The remoteness of the Sun and the harsh conditions prevailing in the solar corona have so far limited the observational data used in the study of solar physics to remote-sensing observations taken either from the ground or from space. In contrast, the 'solar wind laboratory' is directly measured in situ by a fleet of spacecraft measuring the properties of the plasma and magnetic fields at specific points in space. Since 2007, the solar-terrestrial relations observatory (STEREO) has been providing images of the solar wind that flows between the solar corona and spacecraft making in-situ measurements. This has allowed scientists to directly connect processes imaged near the Sun with the subsequent effects measured in the solar wind. This new capability prompted the development of a series of tools and techniques to track heliospheric structures through space. This article presents one of these tools, a web-based interface called the 'Propagation Tool' that offers an integrated research environment to study the evolution of coronal and solar wind structures, such as Coronal Mass Ejections (CMEs), Corotating Interaction Regions (CIRs) and Solar Energetic Particles (SEPs). These structures can be propagated from the Sun outwards to or alternatively inwards from planets and spacecraft situated in the inner and outer heliosphere. In this paper, we present the global architecture of the tool, discuss some of the assumptions made to simulate the evolution of the structures and show how the tool connects to different databases.

IFMIF - Design Study for in Situ Creep Fatigue Tests

International Nuclear Information System (INIS)

Gordeev, S.; Heinzel, V.; Simakov, St.; Stratmanns, E.; Vladimirov, P.; Moeslang, A.

2006-01-01

While the high flux volume (20-50 dpa/fpy) of the International Fusion Materials Irradiation Facility (IFMIF) is dedicated to the irradiation of ∼ 1100 qualified specimens that will be post irradiation examined after disassembling in dedicated Hot Cells, various in situ experiments are foreseen in the medium flux volume (1-20 dpa/fpy). Of specific importance for structural lifetime assessments of fusion power reactors are instrumented in situ creep-fatigue experiments, as they can simulate realistically a superposition of thermal fatigue or creep fatigue and irradiation with fusion relevant neutrons. Based on former experience with in situ fatigue tests under high energy light ion irradiation, a design study has been performed to evaluate the feasibility of in situ creep fatigue tests in the IFMIF medium flux position. The vertically arranged test module for such experiments consists basically of a frame similar to a universal testing machine, but equipped with three pulling rods, driven by independent step motors, instrumentation systems and specimen cooling systems. Therefore, three creep fatigue specimens may be tested at one time in this apparatus. Each specimen is a hollow tube with coolant flow in the specimen interior to maintain individual specimen temperatures. The recently established IFMIF global 3D geometry model was used together the latest McDeLicious code for the neutral and charged particle transport calculations. These comprehensive neutronics calculations have been performed with a fine special resolution of 0.25 cm 3 , showing among others that the specimens will be irradiated with a homogeneous damage rate of up to 13(∼ 9%) dpa/fpy and a fusion relevant damage to helium ratio of 10-12 appm He/dpa. In addition, damage and gas production rates as well as the heat deposition in structural parts of the test module have been calculated. Despite of the vertical gradients in the nuclear heating, CFD code calculations with STAR-CD revealed very

Spin dependent photon structure functions

International Nuclear Information System (INIS)

Manohar, A.V.; Massachusetts Inst. of Tech., Cambridge

1989-01-01

Spin dependent structure functions of the photon are studied using the operator product expansion. There are new twist-two photon and gluon operators which contribute. The structure functions g 1 and F 3 are calculable in QCD, but differ from their free quark values. The corrections to F 3 are suppressed by 1/log Q 2 . The calculation is an extension of the analysis of Witten for the spin averaged structure functions F 1 and F 2 . (orig.)

Structural study on Ni nanowires in an anodic alumina membrane by using in situ heating extended x-ray absorption fine structure and x-ray diffraction techniques

International Nuclear Information System (INIS)

Cai Quan; Chen Xing; Chen Zhongjun; Wang Wei; Mo Guang; Wu Zhonghua; Zhang Junxi; Zhang Lide; Pan Wei

2008-01-01

Polycrystalline Ni nanowires have been prepared by electrochemical deposition in an anodic alumina membrane template with a nanopore size of about 60 nm. In situ heating extended x-ray absorption fine structure and x-ray diffraction techniques are used to probe the atomic structures. The nanowires are identified as being mixtures of nanocrystallites and amorphous phase. The nanocrystallites have the same thermal expansion coefficient, of 1.7 x 10 -5 K -1 , as Ni bulk; however, the amorphous phase has a much larger thermal expansion coefficient of 3.5 x 10 -5 K -1 . Details of the Ni nanowire structures are discussed in this paper

"In Situ Vascular Nerve Graft" for Restoration of Intrinsic Hand Function: An Anatomical Study.

Science.gov (United States)

Mozaffarian, Kamran; Zemoodeh, Hamid Reza; Zarenezhad, Mohammad; Owji, Mohammad

2018-06-01

In combined high median and ulnar nerve injury, transfer of the posterior interosseous nerve branches to the motor branch of the ulnar nerve (MUN) is previously described in order to restore intrinsic hand function. In this operation a segment of sural nerve graft is required to close the gap between the donor and recipient nerves. However the thenar muscles are not innervated by this nerve transfer. The aim of the present study was to evaluate whether the superficial radial nerve (SRN) can be used as an "in situ vascular nerve graft" to connect the donor nerves to the MUN and the motor branch of median nerve (MMN) at the same time in order to address all denervated intrinsic and thenar muscles. Twenty fresh male cadavers were dissected in order to evaluate the feasibility of this modification of technique. The size of nerve branches, the number of axons and the tension at repair site were evaluated. This nerve transfer was technically feasible in all specimens. There was no significant size mismatch between the donor and recipient nerves Conclusions: The possible advantages of this modification include innervation of both median and ulnar nerve innervated intrinsic muscles, preservation of vascularity of the nerve graft which might accelerate the nerve regeneration, avoidance of leg incision and therefore the possibility of performing surgery under regional instead of general anesthesia. Briefly, this novel technique is a viable option which can be used instead of conventional nerve graft in some brachial plexus or combined high median and ulnar nerve injuries when restoration of intrinsic hand function by transfer of posterior interosseous nerve branches is attempted.

Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure

Science.gov (United States)

May, Matthias M.; Lewerenz, Hans-Joachim; Lackner, David; Dimroth, Frank; Hannappel, Thomas

2015-09-01

Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.

In situ macromolecular crystallography using microbeams.

Science.gov (United States)

Axford, Danny; Owen, Robin L; Aishima, Jun; Foadi, James; Morgan, Ann W; Robinson, James I; Nettleship, Joanne E; Owens, Raymond J; Moraes, Isabel; Fry, Elizabeth E; Grimes, Jonathan M; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S; Stuart, David I; Evans, Gwyndaf

2012-05-01

Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams. © 2012 International Union of Crystallography

Nucleation and growth of elastin-like peptide fibril multilayers: an in situ atomic force microscopy study

International Nuclear Information System (INIS)

Yang Guocheng; Yip, Christopher M; Wong, Michael K; Lin, Lauren E

2011-01-01

Controlling how molecules assemble into complex supramolecular architectures requires careful consideration of the subtle inter- and intra-molecular interactions that control their association. This is particularly crucial in the context of assembly at interfaces, where both surface chemistry and structure can play a role in directing structure formation. We report here the results of a study into the self-assembly of the elastin-like peptide EP I on structurally modified highly ordered pyrolytic graphite, including the role of spatial confinement on fibril nucleation and the growth of oriented fibril multilayers. In situ atomic force microscopy performed in fluid and at elevated temperature provided direct evidence of frustrated fibril nuclei and oriented growth of independent fibril domains. These results portend the application of this in situ strategy for studies of the nucleation and growth mechanisms of other fibril- and amyloid-forming proteins.

Sphingomyelinase D activity in model membranes: structural effects of in situ generation of ceramide-1-phosphate.

Directory of Open Access Journals (Sweden)

Roberto P Stock

Full Text Available The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1 ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2 the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3 in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes.

In Situ Thermal Generation of Silver Nanoparticles in 3D Printed Polymeric Structures

Science.gov (United States)

Fantino, Erika; Chiappone, Annalisa; Calignano, Flaviana; Fontana, Marco; Pirri, Fabrizio; Roppolo, Ignazio

2016-01-01

Polymer nanocomposites have always attracted the interest of researchers and industry because of their potential combination of properties from both the nanofillers and the hosting matrix. Gathering nanomaterials and 3D printing could offer clear advantages and numerous new opportunities in several application fields. Embedding nanofillers in a polymeric matrix could improve the final material properties but usually the printing process gets more difficult. Considering this drawback, in this paper we propose a method to obtain polymer nanocomposites by in situ generation of nanoparticles after the printing process. 3D structures were fabricated through a Digital Light Processing (DLP) system by disolving metal salts in the starting liquid formulation. The 3D fabrication is followed by a thermal treatment in order to induce in situ generation of metal nanoparticles (NPs) in the polymer matrix. Comprehensive studies were systematically performed on the thermo-mechanical characteristics, morphology and electrical properties of the 3D printed nanocomposites. PMID:28773716

In Situ Thermal Generation of Silver Nanoparticles in 3D Printed Polymeric Structures

Directory of Open Access Journals (Sweden)

Erika Fantino

2016-07-01

Full Text Available Polymer nanocomposites have always attracted the interest of researchers and industry because of their potential combination of properties from both the nanofillers and the hosting matrix. Gathering nanomaterials and 3D printing could offer clear advantages and numerous new opportunities in several application fields. Embedding nanofillers in a polymeric matrix could improve the final material properties but usually the printing process gets more difficult. Considering this drawback, in this paper we propose a method to obtain polymer nanocomposites by in situ generation of nanoparticles after the printing process. 3D structures were fabricated through a Digital Light Processing (DLP system by disolving metal salts in the starting liquid formulation. The 3D fabrication is followed by a thermal treatment in order to induce in situ generation of metal nanoparticles (NPs in the polymer matrix. Comprehensive studies were systematically performed on the thermo-mechanical characteristics, morphology and electrical properties of the 3D printed nanocomposites.

In situ macromolecular crystallography using microbeams

International Nuclear Information System (INIS)

Axford, Danny; Owen, Robin L.; Aishima, Jun; Foadi, James; Morgan, Ann W.; Robinson, James I.; Nettleship, Joanne E.; Owens, Raymond J.; Moraes, Isabel; Fry, Elizabeth E.; Grimes, Jonathan M.; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S.; Stuart, David I.; Evans, Gwyndaf

2012-01-01

A sample environment for mounting crystallization trays has been developed on the microfocus beamline I24 at Diamond Light Source. The technical developments and several case studies are described. Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams

In situ macromolecular crystallography using microbeams

Energy Technology Data Exchange (ETDEWEB)

Axford, Danny; Owen, Robin L.; Aishima, Jun [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Foadi, James [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Imperial College, London SW7 2AZ (United Kingdom); Morgan, Ann W.; Robinson, James I. [University of Leeds, Leeds LS9 7FT (United Kingdom); Nettleship, Joanne E.; Owens, Raymond J. [Research Complex at Harwell, Rutherford Appleton Laboratory R92, Didcot, Oxfordshire OX11 0DE (United Kingdom); Moraes, Isabel [Imperial College, London SW7 2AZ (United Kingdom); Fry, Elizabeth E.; Grimes, Jonathan M.; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S. [University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Stuart, David I. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Evans, Gwyndaf, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

2012-04-17

A sample environment for mounting crystallization trays has been developed on the microfocus beamline I24 at Diamond Light Source. The technical developments and several case studies are described. Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams.

Structural and functional intermetallics - an overview

International Nuclear Information System (INIS)

Varin, R.A.

2000-01-01

This overview presents the current status of the research and development of both structural and functional intermetallics. On the one hand, the discussion is focused on commercialization and existing industrial applications of intermetallics. Within this frame the applications of titanium aluminides (TiAl) for turbocharger rotors and exhaust valves in automotive industry are being discussed. Advances in the applications of TiAl alloys for the next generation of turbine blades in aerospace/aircraft segment are also presented. The entire spectrum of nickel and iron aluminide alloys developed commercially by the Oak Ridge national Laboratory (USA) and the examples of their application in various segments of industry are thoroughly discussed. Some inroads made in the application of directionally solidified (DS) multiphase niobium silicides (Nb 3 Si+Nb 5 Si 3 ) in situ intermetallic composites with the goal of pushing the service temperature envelope of turbine blades to ∼ 1200-1300 o C are also discussed. On the other hand, various topics in basic or curiosity driven research of titanium aluminides and trialuminides, iron aluminides and high temperature structural silicides are discussed. Some very recent findings on the improvements in fracture toughness and strength of titanium trialuminides and magnetic behaviour of unconventionally cold - worked iron aluminides are highlighted. The topic of functional intermetallics is limited to the systems must suitable for hydrogen storage applications. A perspective on the directions of future research and development of intermetallics is also provided. (author)

From Structure to Circuits: The Contribution of MEG Connectivity Studies to Functional Neurosurgery.

Science.gov (United States)

Pang, Elizabeth W; Snead Iii, O C

2016-01-01

New advances in structural neuroimaging have revealed the intricate and extensive connections within the brain, data which have informed a number of ambitious projects such as the mapping of the human connectome. Elucidation of the structural connections of the brain, at both the macro and micro levels, promises new perspectives on brain structure and function that could translate into improved outcomes in functional neurosurgery. The understanding of neuronal structural connectivity afforded by these data now offers a vista on the brain, in both healthy and diseased states, that could not be seen with traditional neuroimaging. Concurrent with these developments in structural imaging, a complementary modality called magnetoencephalography (MEG) has been garnering great attention because it too holds promise for being able to shed light on the intricacies of functional brain connectivity. MEG is based upon the elemental principle of physics that an electrical current generates a magnetic field. Hence, MEG uses highly sensitive biomagnetometers to measure extracranial magnetic fields produced by intracellular neuronal currents. Put simply then, MEG is a measure of neurophysiological activity, which captures the magnetic fields generated by synchronized intraneuronal electrical activity. As such, MEG recordings offer exquisite resolution in the time and oscillatory domain and, as well, when co-registered with magnetic resonance imaging (MRI), offer excellent resolution in the spatial domain. Recent advances in MEG computational and graph theoretical methods have led to studies of connectivity in the time-frequency domain. As such, MEG can elucidate a neurophysiological-based functional circuitry that may enhance what is seen with MRI connectivity studies. In particular, MEG may offer additional insight not possible by MRI when used to study complex eloquent function, where the precise timing and coordination of brain areas is critical. This article will review the

In situ synchrotron X-ray studies during metal-organic chemical vapor deposition of semiconductors

Energy Technology Data Exchange (ETDEWEB)

Thompson, Carol [Northern Illinois Univ., DeKalb, IL (United States); Argonne National Lab., Argonne, IL (United States); Highland, Matthew J.; Perret, Edith; Fuoss, Paul H.; Streiffer, Stephen K.; Stephenson, G. Brian [Argonne National Lab., Argonne, IL (United States); Richard, Marie-Ingrid [Universite Paul Cezanne Aix-Marseille, Marseille (France)

2012-07-01

In-situ, time-resolved techniques provide valuable insight into the complex interplay of surface structural and chemical evolution occurring during materials synthesis and processing of semiconductors. Our approach is to observe the evolution of surface structure and morphology at the atomic scale in real-time during metal organic vapor phase deposition (MOCVD) by using grazing incidence x-ray scattering and X-ray fluorescence, coupled with visible light scattering. Our vertical-flow MOCVD chamber is mounted on a 'z-axis' surface diffractometer designed specifically for these studies of the film growth, surface evolution and the interactions within a controlled growth environment. These techniques combine the ability of X-rays to penetrate a complex environment for measurements during growth and processing, with the sensitivity of surface scattering techniques to atomic and nanoscale structure. In this talk, we outline our program and discuss examples from our in-situ and real-time X-ray diffraction and fluorescence studies of InN, GaN, and InGaN growth on GaN(0001).

Structural and functional organization of ribosomal genes within the mammalian cell nucleolus.

Science.gov (United States)

Derenzini, Massimo; Pasquinelli, Gianandrea; O'Donohue, Marie-Françoise; Ploton, Dominique; Thiry, Marc

2006-02-01

Data on the in situ structural-functional organization of ribosomal genes in the mammalian cell nucleolus are reviewed here. Major findings on chromatin structure in situ come from investigations carried out using the Feulgen-like osmium ammine reaction as a highly specific electron-opaque DNA tracer. Intranucleolar chromatin shows three different levels of organization: compact clumps, fibers ranging from 11 to 30 nm, and loose agglomerates of extended DNA filaments. Both clumps and fibers of chromatin exhibit a nucleosomal organization that is lacking in the loose agglomerates of extended DNA filaments. In fact, these filaments constantly show a thickness of 2-3 nm, the same as a DNA double-helix molecule. The loose agglomerates of DNA filaments are located in the fibrillar centers, the interphase counterpart of metaphase NORs, therefore being constituted by ribosomal DNA. The extended, non-nucleosomal configuration of this rDNA has been shown to be independent of transcriptional activity and characterizes ribosome genes that are either transcribed or transcriptionally silent. Data reviewed are consistent with a model of control for ribosome gene activity that is not mediated by changes in chromatin structure. The presence of rDNA in mammalian cells always structurally ready for transcription might facilitate a more rapid adjustment of the ribosome production in response to the metabolic needs of the cell.

In Situ TEM Electrical Measurements

DEFF Research Database (Denmark)

Canepa, Silvia; Alam, Sardar Bilal; Ngo, Duc-The

2016-01-01

understanding of complex physical and chemical interactions in the pursuit to optimize nanostructure function and device performance. Recent developments of sample holder technology for TEM have enabled a new field of research in the study of functional nanomaterials and devices via electrical stimulation...... influence the sample by external stimuli, e.g. through electrical connections, the TEM becomes a powerful laboratory for performing quantitative real time in situ experiments. Such TEM setups enable the characterization of nanostructures and nanodevices under working conditions, thereby providing a deeper...... and measurement of the specimen. Recognizing the benefits of electrical measurements for in situ TEM, many research groups have focused their effort in this field and some of these methods have transferred to ETEM. This chapter will describe recent advances in the in situ TEM investigation of nanostructured...

In-situ Transmission Electron Microscopy and Spectroscopy Studies of Interfaces in Li-ion Batteries: Challenges and Opportunities

International Nuclear Information System (INIS)

Wang, Chong M.; Xu, Wu; Liu, Jun; Choi, Daiwon; Arey, Bruce W.; Saraf, Laxmikant V.; Zhang, Jiguang; Yang, Zhenguo; Thevuthasan, Suntharampillai; Baer, Donald R.; Salmon, Norman

2010-01-01

The critical challenge facing the lithium ion battery development is the basic understanding of the structural evolution during the cyclic operation of the battery and the consequence of the structural evolution on the properties of the battery. Although transmission electron microscopy (TEM) and spectroscopy have been evolved to a stage such that it can be routinely used to probe into both the structural and chemical composition of the materials with a spatial resolution of a single atomic column, a direct in-situ TEM observation of structural evolution of the materials in lithium ion battery during the dynamic operation of the battery has never been reported. This is related to three factors: high vacuum operation of a TEM; electron transparency requirement of the region to be observed, and the difficulties dealing with the liquid electrolyte of lithium ion battery. In this paper, we report the results of exploring the in-situ TEM techniques for observation of the interface in lithium ion battery during the operation of the battery. A miniature battery was fabricated using a nanowire and an ionic liquid electrolyte. The structure and chemical composition of the interface across the anode and the electrolyte was studied using TEM imaging, electron diffraction, and electron energy loss spectroscopy. In addition, we also explored the possibilities of carrying out in-situ TEM studies of lithium ion batteries with a solid state electrolyte.

Influence of Structural Defects on Biomineralized ZnS Nanoparticle Dissolution: An In-Situ Electron Microscopy Study

Energy Technology Data Exchange (ETDEWEB)

Eskelsen, Jeremy R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Xu, Jie [Univ. of Texas, El Paso, TX (United States). Geological Sciences; Chiu, Michelle Y. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Moon, Ji-Won [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division; Wilkins, Branford O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Graham, David E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division; Gu, Baohua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division; Pierce, Eric M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division

2017-12-19

The dissolution of metal sulfides, such as ZnS, plays an important role in the fate of metal contaminants in the environment. Here we have examined the dissolution behavior of ZnS nanoparticles synthesized via several abiotic and biological pathways. Specifically, the biogenic ZnS nanoparticles were produced by an anaerobic, metal-reducing bacterium Thermoanaerobacter sp. X513 in a Zn-amended, thiosulfate-containing growth medium, whereas the abiogenic ZnS nanoparticles were produced by mixing an aqueous Zn solution with either H₂S-rich gas or Na₂S solution. For biogenic synthesis, we prepared two types of samples, in the presence or absence of trace silver (Ag). The size distribution, crystal structure, aggregation behavior, and internal defects of the synthesized ZnS nanoparticles were primarily examined using high-resolution transmission electron microscopy coupled with X-ray energy dispersive spectroscopy. The characterization results show that both the biogenic and abiogenic samples were dominantly composed of sphalerite. In the absence of Ag, the biogenic ZnS nanoparticles were significantly larger (i.e., ~10 nm) than the abiogenic ones (i.e., ~3–5 nm) and contained structural defects (e.g., twins and stacking faults). The presence of trace Ag showed a restraining effect on the particle size of the biogenic ZnS, resulting in quantum-dot-sized nanoparticles (i.e., ~3 nm). In situ dissolution experiments for the synthesized ZnS were conducted with a liquid-cell coupled to a transmission electron microscope (LCTEM), and the primary factors (i.e., the presence or absence structural defects) were evaluated for their effects on the dissolution behavior using the biogenic and abiogenic ZnS nanoparticle samples with the largest average particle size. Analysis of the dissolution results (i.e., change in particle radius with time) using the Kelvin equation shows that the defect-bearing biogenic ZnS nanoparticles (γ = 0.799 J/m²) have

In situ X-ray study of the structural evolution of gold nano-domains by spray deposition on thin conductive P3HT films.

Science.gov (United States)

Al-Hussein, M; Schindler, M; Ruderer, M A; Perlich, J; Schwartzkopf, M; Herzog, G; Heidmann, B; Buffet, A; Roth, S V; Müller-Buschbaum, P

2013-02-26

Gold (Au) nanoparticles are deposited from aqueous solution onto one of the most used conductive polymers, namely poly(3-hexylthiophene) (P3HT), using airbrush deposition. We report on the structure formation and packing of the Au nanoparticles after a 5 s spray cycle. In situ grazing incidence small-angle X-ray scattering (GISAXS) measurements with 20 ms time resolution allow a real-time observation of the emergence and evolution of the microstructure during a spray cycle and subsequent solvent evaporation. The results reveal multistage nanoscale ordering of the Au nanoparticles during the spray cycle. Further ex situ atomic force microscopy measurements of the sprayed films showed the formation of Au monolayer islands on top of the polymer film. Our study suggests that the solvent-substrate interaction as well as solvent evaporation kinetics are important factors that need to be taken into consideration in order to grow a compact uniform monolayer film for the fabrication of ultrathin films using airbrush deposition.

In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

KAUST Repository

Avila-Avendano, Jesus

2016-04-09

In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

KAUST Repository

Avila-Avendano, Jesus; Mejia, Israel; Alshareef, Husam N.; Guo, Zaibing; Young, Chadwin; Quevedo-Lopez, Manuel

2016-01-01

In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

Spectrum-to-dose conversion operator value function of a Ge(Li) in-situ environmental gamma-ray spectrometer

International Nuclear Information System (INIS)

Terada, Hiromi; Sakai, Eiji; Katagiri, Masaki

1976-05-01

A spectrum-to-dose conversion operator value function was obtained for a 73cm 3 closed-end coaxial Ge(Li) in-situ environmental gamma-ray spectrometer; factors influencing the function are considered. (auth.)

Structure and Structure-activity Relationship of Functional Organic Molecules

Institute of Scientific and Technical Information of China (English)

2011-01-01

@@ Research theme The group is made up of junior scientists from the State Key Laboratory of Elemento-organic Chemistry, Nankai University.The scientists focus their studis on the structure and structure-activity relationship of functional organic molecules not only because it has been the basis of their research, but also because the functional study of organic compounds is now a major scientific issue for organic chemists around the world.

Structural and microstructural changes during anion exchange of CoAl layered double hydroxides. An in situ X-ray powder diffraction study

International Nuclear Information System (INIS)

Johnsen, Rune E.; Krumeich, Frank; Norby, Poul

2010-01-01

Anion-exchange processes in cobalt-aluminium layered double hydroxides (LDHs) were studied by in situ synchrotron X-ray powder diffraction (XRPD). The processes investigated were CoAl-CO 3 →CoAl-Cl →CoAl-CO 3 , CoAl-Cl→CoAl-NO 3 and CoAl-CO 3 →CoAl-SO 4 . The XRPD data show that the CoAl-CO 3 →CoAl-Cl process is a two-phase transformation, where the amount of the CoAl-CO 3 phase decreases exponentially while that of the CoAl-Cl phase increases exponentially. Energy-dispersive X-ray spectroscopy (EDXS) studies of a partially chloride-exchanged CoAl-CO 3 LDH sample along with in situ XRPD data suggested that the individual particles in the CoAl-CO 3 sample are generally anion-exchanged with chloride one at a time. In contrast with the CoAl-CO 3 →CoAl-Cl transformation, the XRPD data show that the reverse CoAl-Cl→CoAl-CO 3 process is a one-phase transformation. Rietveld refinements indicate that the occupancy factors of the carbon and oxygen sites of the carbonate group increase, while that of the chloride site decreases. In the CoAl-Cl→CoAl-NO 3 anion-exchange reaction, the XRPD patterns reveal the existence of two intermediate phases in addition to the initial CoAl-Cl and final CoAl-NO 3 phases. The in situ data indicate that one of these intermediates is a mixed nitrate- and chloride-based LDH phase, where the disorder decreases as the nitrate content increases. The XRPD data of the partial CoAl-CO 3 →CoAl-SO 4 anion-exchange reaction show that the process is a two-phase transformation involving a sulfate-containing LDH with a 1H polytype structure. (orig.)

The Pronominal System of the Soqotri Dialects: A structural and functional Study

Directory of Open Access Journals (Sweden)

Khaled Awadh Bin Mukhashin

2016-12-01

Full Text Available This study aims at describing structurally and functionally the pronominal system of the three main dialects of Soqotri, an endangered Modern south Arabian language spoken in the Island of Soqotra, Yemen. A part of the data presented in the study has been taken from my PhD thesis written in 2009. New data were collected from the field in 2012 and added to the study. The Study follows a descriptive method, therefore, showing no argumentation. The study reveals the structure and functions of the Soqotri rich pronominal system. It shows that the three Soqotri dialects (Eastern Soqotri Dialect, Central Soqotri Dialect and Western Soqotri Dialect have personal pronouns, possessive pronouns, demonstrative pronoun, reflexive pronouns, reciprocal pronouns, relative pronouns and interrogative pronouns. It also shows that these pronouns are usually of two types (independent and dependent inflecting for person, number and gender.

Subjective Cognitive Decline: Mapping Functional and Structural Brain Changes-A Combined Resting-State Functional and Structural MR Imaging Study.

Science.gov (United States)

Sun, Yu; Dai, Zhengjia; Li, Yuxia; Sheng, Can; Li, Hongyan; Wang, Xiaoni; Chen, Xiaodan; He, Yong; Han, Ying

2016-10-01

Purpose To determine whether individuals with subjective cognitive decline (SCD) exhibit functional and structural brain alterations by using resting-state functional and structural magnetic resonance (MR) imaging. Materials and Methods This study received institutional review board approval, and all participants gave informed consent. Resting-state functional MR imaging and structural MR imaging techniques were used to measure amplitude of low-frequency fluctuations (ALFF) and regional gray matter volume in 25 subjects with SCD (mean age, 65.52 years ± 6.12) and 61 control subjects (mean age, 64.11 years ± 8.59). Voxel-wise general linear model analyses were used to examine between-group differences in ALFF or in gray matter volume and to further determine the brain-behavioral relationship. Results Subjects with SCD exhibited higher ALFF values than did control subjects in the bilateral inferior parietal lobule (left: 0.44 ± 0.25 vs 0.27 ± 0.18, respectively; P = .0003; right: 1.46 ± 0.45 vs 1.10 ± 0.37, respectively; P = .0015), right inferior (0.45 ± 0.15 vs 0.37 ± 0.08, repectively; P = .0106) and middle (1.03 ± 0.32 vs 0.83 ± 0.20, respectively; P = .0008) occipital gyrus, right superior temporal gyrus (0.11 ± 0.07 vs 0.07 ± 0.04, respectively; P = .0016), and right cerebellum posterior lobe (0.51 ± 0.27 vs 0.39 ± 0.15, respectively; P = .0010). In the SCD group, significant correlations were found between Auditory Verbal Learning Test recognition scores and ALFF in the left inferior parietal lobe (r = -0.79, P Learning Test immediate recall scores and ALFF values in the right middle occipital gyrus (r = -0.64, P = .002). Nonsignificant group differences were found in gray matter volume (P > .05, corrected). Conclusion Individuals with SCD had altered spontaneous functional activity, suggesting that resting-state functional MR imaging may be a noninvasive method for characterizing SCD. (©) RSNA, 2016 Online supplemental material is available for

In-situ Spectroscopic Studies and Modelling of Crystallization Processes of Sulphuric Acid Catalysts

DEFF Research Database (Denmark)

Oehlers, C.; Fehrmann, Rasmus; Masters, Stephen Grenville

1996-01-01

Deactivation of commercial and prototype sulphuric acid catalysts has been investigated in-situ by ESR spectroscopy. The influence of support pore structure,and the chemical composition of the catalyst and the gas phase was dicussed.A statistical lattice model was applied to describe the crystall......Deactivation of commercial and prototype sulphuric acid catalysts has been investigated in-situ by ESR spectroscopy. The influence of support pore structure,and the chemical composition of the catalyst and the gas phase was dicussed.A statistical lattice model was applied to describe...

In-situ measurement of mechanical properties of structural components using cyclic ball indentation technique

International Nuclear Information System (INIS)

Chatterjee, S.; Madhusoodanan, K.; Panwar, Sanjay; Rupani, B.B.

2007-01-01

Material properties of components change during service due to environmental conditions. Measurement of mechanical properties of the components is important for assessing their fitness for service. In many instances, it is not possible to remove sizable samples from the component for doing the measurement in laboratory. In-situ technique for measurement of mechanical properties has great significance in such cases. One of the nondestructive methods that can be adopted for in-situ application is based on cyclic ball indentation technique. It involves multiple indentation cycles (at the same penetration location) on a metallic surface by a spherical indenter. Each cycle consists of indentation, partial unload and reload sequences. Presently, commercial systems are available for doing indentation test on structural component for limited applications. But, there is a genuine need of remotely operable compact in-situ property measurement system. Considering the importance of such applications Reactor Engineering Division of BARC has developed an In-situ Property Measurement System (IProMS), which can be used for in-situ measurement of mechanical properties of a flat or tubular component. This paper highlights the basic theory of measurement, qualification tests on IProMS and results from tests done on flat specimens and tubular component. (author)

Structural investigations of LiFePO4 electrodes and in situ studies by Fe X-ray absorption spectroscopy

International Nuclear Information System (INIS)

Deb, Aniruddha; Bergmann, Uwe; Cramer, S.P.; Cairns, Elton J.

2005-01-01

Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on electrodes containing LiFePO 4 to determine the local atomic and electronic structure and their stability with electrochemical cycling. A versatile electrochemical in situ cell has been constructed for long-term soft and hard X-ray experiments for the structural investigation on battery electrodes during the lithium-insertion/extraction processes. The device is used here for an X-ray absorption spectroscopic study of lithium insertion/extraction in a LiFePO 4 electrode, where the electrode contained about 7.7 mg of LiFePO 4 on a 20 μm thick Al-foil. Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on this electrode to determine the local atomic and electronic structure and their stability with electrochemical cycling. The initial state (LiFePO 4 ) showed iron to be in the Fe 2+ state corresponding to the initial state (0.0 mAh) of the cell, whereas in the delithiated state (FePO 4 ) iron was found to be in the Fe 3+ state corresponding to the final charged state (3 mAh). XANES region of the XAS spectra revealed a high spin configuration for the two states (Fe (II), d 6 and Fe (III), d 5 ). The results confirm that the olivine structure of the LiFePO 4 and FePO 4 is retained by the electrodes in agreement with the XRD observations reported previously. These results confirm that LiFePO 4 cathode material retains good structural short-range order leading to superior cycling capability

High spin structure functions

International Nuclear Information System (INIS)

Khan, H.

1990-01-01

This thesis explores deep inelastic scattering of a lepton beam from a polarized nuclear target with spin J=1. After reviewing the formation for spin-1/2, the structure functions for a spin-1 target are defined in terms of the helicity amplitudes for forward compton scattering. A version of the convolution model, which incorporates relativistic and binding energy corrections is used to calculate the structure functions of a neutron target. A simple parameterization of these structure functions is given in terms of a few neutron wave function parameters and the free nucleon structure functions. This allows for an easy comparison of structure functions calculated using different neutron models. (author)

Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

International Nuclear Information System (INIS)

McGinnis, M. J.; Pessiki, S.

2006-01-01

The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement

Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

Science.gov (United States)

McGinnis, M. J.; Pessiki, S.

2006-03-01

The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement.

Structure functions from chiral soliton models

International Nuclear Information System (INIS)

Weigel, H.; Reinhardt, H.; Gamberg, L.

1997-01-01

We study nucleon structure functions within the bosonized Nambu-Jona-Lasinio (NJL) model where the nucleon emerges as a chiral soliton. We discuss the model predictions on the Gottfried sum rule for electron-nucleon scattering. A comparison with a low-scale parametrization shows that the model reproduces the gross features of the empirical structure functions. We also compute the leading twist contributions of the polarized structure functions g 1 and g 2 in this model. We compare the model predictions on these structure functions with data from the E143 experiment by GLAP evolving them from the scale characteristic for the NJL-model to the scale of the data

When structure affects function--the need for partial volume effect correction in functional and resting state magnetic resonance imaging studies.

Science.gov (United States)

Dukart, Juergen; Bertolino, Alessandro

2014-01-01

Both functional and also more recently resting state magnetic resonance imaging have become established tools to investigate functional brain networks. Most studies use these tools to compare different populations without controlling for potential differences in underlying brain structure which might affect the functional measurements of interest. Here, we adapt a simulation approach combined with evaluation of real resting state magnetic resonance imaging data to investigate the potential impact of partial volume effects on established functional and resting state magnetic resonance imaging analyses. We demonstrate that differences in the underlying structure lead to a significant increase in detected functional differences in both types of analyses. Largest increases in functional differences are observed for highest signal-to-noise ratios and when signal with the lowest amount of partial volume effects is compared to any other partial volume effect constellation. In real data, structural information explains about 25% of within-subject variance observed in degree centrality--an established resting state connectivity measurement. Controlling this measurement for structural information can substantially alter correlational maps obtained in group analyses. Our results question current approaches of evaluating these measurements in diseased population with known structural changes without controlling for potential differences in these measurements.

Mechanical Anisotropy and Pressure Induced Structural Changes in Piroxicam Crystals Probed by In Situ Indentation and Raman Spectroscopy

Science.gov (United States)

Manimunda, Praveena; Hintsala, Eric; Asif, Syed; Mishra, Manish Kumar

2017-01-01

The ability to correlate mechanical and chemical characterization techniques in real time is both lacking and powerful tool for gaining insights into material behavior. This is demonstrated through use of a novel nanoindentation device equipped with Raman spectroscopy to explore the deformation-induced structural changes in piroxicam crystals. Mechanical anisotropy was observed in two major faces ( 0bar{1}1 ) and (011), which are correlated to changes in the interlayer interaction from in situ Raman spectra recorded during indentation. The results of this study demonstrate the considerable potential of an in situ Raman nanoindentation instrument for studying a variety of topics, including stress-induced phase transformation mechanisms, mechanochemistry, and solid state reactivity under mechanical forces that occur in molecular and pharmaceutical solids.

NMR Studies of the Structure and Function of the HIV-1 5′-Leader

Directory of Open Access Journals (Sweden)

Sarah C. Keane

2016-12-01

Full Text Available The 5′-leader of the human immunodeficiency virus type 1 (HIV-1 genome plays several critical roles during viral replication, including differentially establishing mRNA versus genomic RNA (gRNA fates. As observed for proteins, the function of the RNA is tightly regulated by its structure, and a common paradigm has been that genome function is temporally modulated by structural changes in the 5′-leader. Over the past 30 years, combinations of nucleotide reactivity mapping experiments with biochemistry, mutagenesis, and phylogenetic studies have provided clues regarding the secondary structures of stretches of residues within the leader that adopt functionally discrete domains. More recently, nuclear magnetic resonance (NMR spectroscopy approaches have been developed that enable direct detection of intra- and inter-molecular interactions within the intact leader, providing detailed insights into the structural determinants and mechanisms that regulate HIV-1 genome packaging and function.

Solution spectroelectrochemical cell for in situ X-ray absorption fine structure

International Nuclear Information System (INIS)

Antonio, M.R.; Soderholm, L.

1995-01-01

A purpose-built spectroelectrochemical cell for in situ fluorescence XAFS (X-ray Absorption Fine Structure) measurements of bulk solution species during constant-potential electrolysis is described. The cell performance was demonstrated by the collection of europium L 3 -edge XANES (X-ray Absorption Near Edge Structure) throughout the course of electrolysis of an aqueous solution of EuCl 3 ·6H 2 O in 1 M H 2 SO 4 . The europium L 3 -edge resonances reported here for the Eu III and Eu II ions demonstrate that their 2p 3/2 → 5d electronic transition probabilities are not the same

Hadron structure functions

International Nuclear Information System (INIS)

Martin, F.

1981-03-01

The x dependence of hadron structure functions is investigated. If quarks can exist in very low mass states (10 MeV for d and u quarks) the pion structure function is predicted to behave like (1-x) and not (1-x) 2 in a x-region around 1. Relativistic and non-relativistic quark bound state pictures of hadrons are considered together with their relation with the Q 2 evolution of structure functions. Good agreement with data is in general obtained

Growth studies of CVD-MBE by in-situ diagnostics

Science.gov (United States)

Maracas, George N.; Steimle, Timothy C.

1992-10-01

This is the final technical report for the three year DARPA-URI program 'Growth Studies of CVD-MBE by in-situ Diagnostics'. The goals of the program were to develop non-invasive, real time epitaxial growth monitoring techniques and combine them to gain an understanding of processes that occur during MBE growth from gas sources. We have adapted these techniques to a commercially designed gas source MBE system (Vacuum Generators Inc.) to facilitate technology transfer out of the laboratory into industrial environments. The in-situ measurement techniques of spectroscopic ellipsometry (SE) and laser induced fluorescence (LIF) have been successfully implemented to monitor the optical and chemical properties of the growing epitaxial film and the gas phase reactants. The ellipsometer was jointly developed with the J. Woolam Co. and has become a commercial product. The temperature dependence of group 3 and 5 desorption from GaAs and InP has been measured as well as the incident effusion cell fluxes. The temporal evolution of the growth has also been measured both by SE and LIF to show the smoothing of heterojunction surfaces during growth interruption. Complicated microcavity optical device structures have been monitored by ellipsometry in real time to improve device quality. This data has been coupled with the structural information obtained from reflection high energy electron diffraction (RHEED) to understand the growth processes in binary and ternary bulk 3-5 semiconductors and heterojunctions.

Structure of spinel at high temperature using in-situ XANES study at the Al and Mg K-edge

Energy Technology Data Exchange (ETDEWEB)

Ligny, D de [Universite Claude Bernard Lyon 1, LPCML, 69622 Villeurbanne (France); Neuville, D R [Physique des Mineraux et Magmas, Geochimie-Cosmochimie, CNRS-IPGP, 4 place Jussieu, 75005 Paris (France); Flank, A-M; Lagarde, P, E-mail: deligny@pcml.univ-lyon1.f [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 France (France)

2009-11-15

We present structural information obtained on spinel at high temperature (298-2400 K) using in situ XANES at the Mg and Al K-edge. Spinel, {sup [4]}(Al{sub x},Mg{sub 1-x}){sup [6]}(Al{sub 2-x},Mg{sub x})O{sub 4}, with increasing temperature, show a substitution of Mg by Al and Al by Mg in their respective sites. This substitution corresponds to an inversion of the Mg and Al sites. Furthermore, both experiments at the Al and Mg K-edges are in good agreement with XANES calculation made using FDMNES code.

In situ studies of oxide nucleation, growth, and transformation using slow electrons

Science.gov (United States)

Flege, Jan Ingo; Grinter, David C.

2018-05-01

Surface processes such as metal oxidation and metal oxide growth invariably influence the physical and chemical properties of materials and determine their interaction with their surroundings and hence their functionality in many technical applications. On a fundamental level, these processes are found to be governed by a complex interplay of thermodynamic variables and kinetic constraints, resulting in a rich variety of material-specific phenomena. In this review article, we discuss recent results and insights on transition metal oxidation and rare-earth oxide growth acquired by low-energy electron microscopy and related techniques. We demonstrate that the use of in situ surface sensitive methods is a prerequisite to gaining a deeper understanding of the underlying concepts and the mechanisms responsible for the emerging oxide structure and morphology. Furthermore, examples will be provided on how structural and chemical modifications of the oxide films and nanostructures can be followed in real-time and analyzed in terms of local reactivity and cooperative effects relevant for heterogeneous model catalysis.

Surface structure and properties of functionalized nanodiamonds: a first-principles study

International Nuclear Information System (INIS)

Datta, Aditi; Kirca, Mesut; Fu Yao; To, Albert C

2011-01-01

The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest. First, the structure of NDs of technologically relevant size (∼5 nm) was optimized using classical mechanics based molecular mechanics simulations. Quantum mechanics based density functional theory (DFT) was then employed to analyse the properties of smaller relevant parts of the optimized cluster further to address the effect of functionalization on the stability of the cluster and reactivity at its surface. It is found that functionalization is preferred over reconstruction at the (100) surface and promotes graphitization in the (111) surface for NDs functionalized with the carbonyl oxygen (C = O) group. It is also seen that the edges of ND are the preferred sites for functionalization with the carboxyl group (-COOH) vis-a-vis the corners of ND.

Surface structure and properties of functionalized nanodiamonds: a first-principles study

Energy Technology Data Exchange (ETDEWEB)

Datta, Aditi; Kirca, Mesut; Fu Yao; To, Albert C, E-mail: albertto@pitt.edu [Department of Mechanical Engineering and Materials Science and Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

2011-02-11

The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest. First, the structure of NDs of technologically relevant size ({approx}5 nm) was optimized using classical mechanics based molecular mechanics simulations. Quantum mechanics based density functional theory (DFT) was then employed to analyse the properties of smaller relevant parts of the optimized cluster further to address the effect of functionalization on the stability of the cluster and reactivity at its surface. It is found that functionalization is preferred over reconstruction at the (100) surface and promotes graphitization in the (111) surface for NDs functionalized with the carbonyl oxygen (C = O) group. It is also seen that the edges of ND are the preferred sites for functionalization with the carboxyl group (-COOH) vis-a-vis the corners of ND.

In situ reduction of antibacterial silver ions to metallic silver nanoparticles on bioactive glasses functionalized with polyphenols

Energy Technology Data Exchange (ETDEWEB)

Ferraris, S., E-mail: sara.ferraris@polito.it [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy); Miola, M. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy); Department of Health Sciences, Università del Piemonte Orientale UPO, Via Solaroli 17, 28100, Novara (Italy); Cochis, A.; Azzimonti, B.; Rimondini, L. [Department of Health Sciences, Università del Piemonte Orientale UPO, Via Solaroli 17, 28100, Novara (Italy); Prenesti, E. [Department of Chemistry, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, 10125 (Italy); Vernè, E. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy)

2017-02-28

Highlights: • Gallic acid and natural polyphenols were grafted onto bioactive glasses. • Grafting ability was dependent on glass reactivity. • In situ reduction of silver nanoparticles was performed onto functionalized glasses. • Bioactive glasses decorated with silver nanoparticles showed antibacterial activity. - Abstract: The realization of surfaces with antibacterial properties due to silver nanoparticles loaded through a green approach is a promising research challenge of the biomaterial field. In this research work, two bioactive glasses have been doubly surface functionalized with polyphenols (gallic acid or natural polyphenols extracted from red grape skins and green tea leaves) and silver nanoparticles deposited by in situ reduction from a silver nitrate aqueous solution. The presence of biomolecules – showing reducing ability to directly obtain in situ metallic silver – and silver nanoparticles was investigated by means of UV–vis spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM). The antibacterial activity of the modified surfaces was tested against a multidrug resistant Staphylococcus aureus bacterial strain.

Influence of Magnesium Content on the Local Structure of Amorphous Calcium Carbonate (ACC): Real Time Determination by In Situ PDF Analysis

Science.gov (United States)

Mergelsberg, S. T.; Ulrich, R. N.; Michel, F. M.; Dove, P. M.

2016-12-01

Calcium carbonate minerals are an essential component in the exoskeletons of crustaceans and mollusks. The onset of exoskeleton mineralization includes the precipitation of amorphous calcium carbonate (ACC) as a reactive intermediate that later transforms to produce diverse structures. Despite the importance of ACC as a critical phase during skeleton formation, the chemical and physical properties are not well characterized at conditions that approximate biological environments. Of particular interest are the solubility of ACC, the short-range structure at the time of formation, and the evolution of ACC structure to final products. Recent advances showing the widespread occurrence of multistep pathways to mineralization in biological and geological settings (De Yoreo et al., 2015) underline the importance of understanding amorphous intermediates. Using quantitative laboratory techniques developed by our research group (Blue et al., 2013; Blue and Dove, 2015; Blue et al., in press), this experimental study quantifies the solubility of ACC in parallel with the physical characterization of the corresponding structure. We measured ACC solubility at specific time points during the precipitation and during its subsequent evolution under the mild pH conditions that approximate biological and environmental conditions. In parallel experiments, structural data were collected from in situ pair distribution function (PDF) analyses were conducted to follow the evolution of individual samples from initial precipitation to final product. The measurements are leading to a quantitative solubility function for ACC with variable Mg contents and an x-ray based understanding of ACC structure in the same particles. We are also finding temporal changes in the short-range order of ACC after precipitation and this order is dependent upon Mg content. Moreover, the data show Mg distribution through the ACC particles is dependent upon total alkalinity. Insights from this study hold promise

An in situ study of the adsorption behavior of functionalized particles on selfassembled monolayers via different chemical interactions

NARCIS (Netherlands)

Ling, X.Y.; Malaquin, Laurent; Reinhoudt, David; Wolf, Heiko; Huskens, Jurriaan

2007-01-01

The formation of particle monolayers by convective assembly was studied in situ with three different kinds of particle-surface interactions: adsorption onto native surfaces, with additional electrostatic interactions, and with supramolecular host-guest interactions. In the first case

Functional nanometer-scale structures

Science.gov (United States)

Chan, Tsz On Mario

Nanometer-scale structures have properties that are fundamentally different from their bulk counterparts. Much research effort has been devoted in the past decades to explore new fabrication techniques, model the physical properties of these structures, and construct functional devices. The ability to manipulate and control the structure of matter at the nanoscale has made many new classes of materials available for the study of fundamental physical processes and potential applications. The interplay between fabrication techniques and physical understanding of the nanostructures and processes has revolutionized the physical and material sciences, providing far superior properties in materials for novel applications that benefit society. This thesis consists of two major aspects of my graduate research in nano-scale materials. In the first part (Chapters 3--6), a comprehensive study on the nanostructures based on electrospinning and thermal treatment is presented. Electrospinning is a well-established method for producing high-aspect-ratio fibrous structures, with fiber diameter ranging from 1 nm--1 microm. A polymeric solution is typically used as a precursor in electrospinning. In our study, the functionality of the nanostructure relies on both the nanostructure and material constituents. Metallic ions containing precursors were added to the polymeric precursor following a sol-gel process to prepare the solution suitable for electrospinning. A typical electrospinning process produces as-spun fibers containing both polymer and metallic salt precursors. Subsequent thermal treatments of the as-spun fibers were carried out in various conditions to produce desired structures. In most cases, polymer in the solution and the as-spun fibers acted as a backbone for the structure formation during the subsequent heat treatment, and were thermally removed in the final stage. Polymers were also designed to react with the metallic ion precursors during heat treatment in some

Hierarchically structured transparent hybrid membranes by in situ growth of mesostructured organosilica in host polymer

Science.gov (United States)

Vallé, Karine; Belleville, Philippe; Pereira, Franck; Sanchez, Clément

2006-02-01

The elaborate performances characterizing natural materials result from functional hierarchical constructions at scales ranging from nanometres to millimetres, each construction allowing the material to fit the physical or chemical demands occurring at these different levels. Hierarchically structured materials start to demonstrate a high input in numerous promising applied domains such as sensors, catalysis, optics, fuel cells, smart biologic and cosmetic vectors. In particular, hierarchical hybrid materials permit the accommodation of a maximum of elementary functions in a small volume, thereby optimizing complementary possibilities and properties between inorganic and organic components. The reported strategies combine sol-gel chemistry, self-assembly routes using templates that tune the material's architecture and texture with the use of larger inorganic, organic or biological templates such as latex, organogelator-derived fibres, nanolithographic techniques or controlled phase separation. We propose an approach to forming transparent hierarchical hybrid functionalized membranes using in situ generation of mesostructured hybrid phases inside a non-porogenic hydrophobic polymeric host matrix. We demonstrate that the control of the multiple affinities existing between organic and inorganic components allows us to design the length-scale partitioning of hybrid nanomaterials with tuned functionalities and desirable size organization from ångström to centimetre. After functionalization of the mesoporous hybrid silica component, the resulting membranes have good ionic conductivity offering interesting perspectives for the design of solid electrolytes, fuel cells and other ion-transport microdevices.

Covalent functionalization of carbon nanotube forests grown in situ on a metal-silicon chip

KAUST Repository

Johansson, Johan R.

2012-03-12

We report on the successful covalent functionalization of carbon nanotube (CNT) forests, in situ grown on a silicon chip with thin metal contact film as the buffer layer between the CNT forests and the substrate. The CNT forests were successfully functionalized with active amine and azide groups, which can be used for further chemical reactions. The morphology of the CNT forests was maintained after the functionalization. We thus provide a promising foundation for a miniaturized biosensor arrays system that can be easily integrated with Complementary Metal-Oxide Semiconductor (CMOS) technology.

Covalent functionalization of carbon nanotube forests grown in situ on a metal-silicon chip

KAUST Repository

Johansson, Johan R.; Bosaeus, Niklas; Kann, Nina; Å kerman, Bjö rn; Nordé n, Bengt; Khalid, Waqas

2012-01-01

We report on the successful covalent functionalization of carbon nanotube (CNT) forests, in situ grown on a silicon chip with thin metal contact film as the buffer layer between the CNT forests and the substrate. The CNT forests were successfully functionalized with active amine and azide groups, which can be used for further chemical reactions. The morphology of the CNT forests was maintained after the functionalization. We thus provide a promising foundation for a miniaturized biosensor arrays system that can be easily integrated with Complementary Metal-Oxide Semiconductor (CMOS) technology.

In situ ice and structure thickness monitoring using integrated and flexible ultrasonic transducers

International Nuclear Information System (INIS)

Liu, Q; Wu, K-T; Kobayashi, M; Jen, C-K; Mrad, N

2008-01-01

Two types of ultrasonic sensors are presented for in situ capability development of ice detection and structure thickness measurement. These piezoelectric film based sensors have been fabricated by a sol–gel spray technique for aircraft environments and for temperatures ranging from −80 to 100 °C. In one sensor type, piezoelectric films of thickness greater than 40 µm are deposited directly onto the interior of a 1.3 mm thick aluminum (Al) alloy control surface (stabilizer) of an aircraft wing structure as integrated ultrasonic transducers (UTs). In the other sensor type, piezoelectric films are coated onto a 50 µm thick polyimide membrane as flexible UTs. These were subsequently glued onto similar locations at the same control surfaces. In situ monitoring of stabilizer outer skin thickness was performed. Ice build-up ranging from a fraction of 1 mm to less than 1.5 mm was also detected on a 3 mm thick Al plate. Measurements using these ultrasonic sensors agreed well with those obtained by a micrometer. Tradeoffs of these two approaches are presented

A Mapping Between Structural and Functional Brain Networks.

Science.gov (United States)

Meier, Jil; Tewarie, Prejaas; Hillebrand, Arjan; Douw, Linda; van Dijk, Bob W; Stufflebeam, Steven M; Van Mieghem, Piet

2016-05-01

The relationship between structural and functional brain networks is still highly debated. Most previous studies have used a single functional imaging modality to analyze this relationship. In this work, we use multimodal data, from functional MRI, magnetoencephalography, and diffusion tensor imaging, and assume that there exists a mapping between the connectivity matrices of the resting-state functional and structural networks. We investigate this mapping employing group averaged as well as individual data. We indeed find a significantly high goodness of fit level for this structure-function mapping. Our analysis suggests that a functional connection is shaped by all walks up to the diameter in the structural network in both modality cases. When analyzing the inverse mapping, from function to structure, longer walks in the functional network also seem to possess minor influence on the structural connection strengths. Even though similar overall properties for the structure-function mapping are found for different functional modalities, our results indicate that the structure-function relationship is modality dependent.

Multi-functional composite structures

Science.gov (United States)

Mulligan, Anthony C.; Halloran, John; Popovich, Dragan; Rigali, Mark J.; Sutaria, Manish P.; Vaidyanathan, K. Ranji; Fulcher, Michael L.; Knittel, Kenneth L.

2004-10-19

Fibrous monolith processing techniques to fabricate multifunctional structures capable of performing more than one discrete function such as structures capable of bearing structural loads and mechanical stresses in service and also capable of performing at least one additional non-structural function.

Cost accounting method for in-situ leaching mines and its application

International Nuclear Information System (INIS)

Cheng Zongfang; Yang Yihan; Liu Zhanxiang; Lai Yongchun

2008-01-01

Cost structures and accounting method for in-situ leaching mines are studied according to the technical characteeristics of in-situ leaching. A method of cost forecast for in-situ leaching deposit or mine area is presented, and the application of this method is illustrated with examples. (authors)

Polarized DIS Structure Functions from Neural Networks

International Nuclear Information System (INIS)

Del Debbio, L.; Guffanti, A.; Piccione, A.

2007-01-01

We present a parametrization of polarized Deep-Inelastic-Scattering (DIS) structure functions based on Neural Networks. The parametrization provides a bias-free determination of the probability measure in the space of structure functions, which retains information on experimental errors and correlations. As an example we discuss the application of this method to the study of the structure function g 1 p (x,Q 2 )

Case study of the gradient features of in situ concrete

Directory of Open Access Journals (Sweden)

Pengkun Hou

2014-01-01

Full Text Available The recognition of gradient features of the properties of in situ concrete is important for the interpretation/prediction of service life. In this work, the gradient features: water absorption, porosity, mineralogy, morphology and micromechanical properties were studied on two in situ road concretes (15 and 5 years old, respectively by weighing, MIP, XRD, IR, SEM/EDS and micro-indentation techniques. Results showed that a coarsening trend of the pores of the concrete leads to a gradual increase of liquid transport property from inside to outside. Although the carbonation of the exposed surface results in a compact microstructure of the paste, its combined action with calcium-leaching leads to a comparable porosity of different concrete layers. Moreover, the combining factors result in three morphological features, i.e. a porous and granular exposed-layer, a fibrous and porous subexposed-layer and a compact inner-layer. Micro-indentation test results showed that a hard layer that moves inward with aging exists due to the alterations of the mineralogy, the pore and the gel structure.

In situ functionalization and PEO coating of iron oxide nanocrystals using seeded emulsion polymerization.

Science.gov (United States)

Kloust, Hauke; Schmidtke, Christian; Feld, Artur; Schotten, Theo; Eggers, Robin; Fittschen, Ursula E A; Schulz, Florian; Pöselt, Elmar; Ostermann, Johannes; Bastús, Neus G; Weller, Horst

2013-04-16

Herein we demonstrate that seeded emulsion polymerization is a powerful tool to produce multiply functionalized PEO coated iron oxide nanocrystals. Advantageously, by simple addition of functional surfactants, functional monomers, or functional polymerizable linkers-solely or in combinations thereof-during the seeded emulsion polymerization process, a broad range of in situ functionalized polymer-coated iron oxide nanocrystals were obtained. This was demonstrated by purposeful modulation of the zeta potential of encapsulated iron oxide nanocrystals and conjugation of a dyestuff. Successful functionalization was unequivocally proven by TXRF. Furthermore, the spatial position of the functional groups can be controlled by choosing the appropriate spacers. In conclusion, this methodology is highly amenable for combinatorial strategies and will spur rapid expedited synthesis and purposeful optimization of a broad scope of nanocrystals.

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

Science.gov (United States)

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.

In situ Low-temperature Pair Distribution Function (PDF) Analysis of CH4 and CO2 Hydrates

Science.gov (United States)

Cladek, B.; Everett, M.; McDonnell, M.; Tucker, M.; Keffer, D.; Rawn, C.

2017-12-01

Gas hydrates occur in ocean floor and sub-surface permafrost deposits and are stable at moderate to high pressures and low temperatures. They are a clathrate structure composed of hydrogen bonded water cages that accommodate a wide variety of guest molecules. CO2 and CH4 hydrates both crystallize as the cubic sI hydrate and can form a solid solution. Natural gas hydrates are interesting as a potential methane source and for CO2 sequestration. Long-range diffraction studies on gas hydrates give valuable structural information but do not provide a detailed understanding of the disordered gas molecule interactions with the host lattice. In-situ low temperature total scattering experiments combined with pair distribution function (PDF) analysis are used to investigate the gas molecule motions and guest-cage interactions. CO2 and methane hydrates exhibit different decomposition behavior, and CO2 hydrate has a smaller lattice parameter despite it being a relatively larger molecule. Total scattering studies characterizing both the short- and long-range order simultaneously help to elucidate the structural source of these phenomena. Low temperature neutron total scattering data were collected using the Nanoscale Ordered MAterials Diffractometer (NOMAD) beamline at the Spallation Neutron Source (SNS) on CO2 and CH4 hydrates synthesized with D2O. Guest molecule motion within cages and interactions between gases and cages are investigated through the hydrate stability and decomposition regions. Data were collected from 2-80 K at a pressure of 55 mbar on CO2 and CH4 hydrates, and from 80-270 K at 25 bar on CH4 hydrate. The hydrate systems were modeled with classical molecular dynamic (MD) simulations to provide an analysis of the total energy into guest-guest, guest-host and host-host contributions. Combined Reitveld and Reverse Monte Carlo (RMC) structure refinement were used to fit models of the data. This combined modeling and simulation characterizes the effects of CO2 and

In situ transmission electron microscopy for magnetic nanostructures

DEFF Research Database (Denmark)

Ngo, Duc-The; Kuhn, Luise Theil

2016-01-01

Nanomagnetism is a subject of great interest because of both application and fundamental aspects in which understanding of the physical and electromagnetic structure of magnetic nanostructures is essential to explore the magnetic properties. Transmission electron microscopy (TEM) is a powerful tool...... that allows understanding of both physical structure and micromagnetic structure of the thin samples at nanoscale. Among TEM techniques, in situ TEM is the state-of-the-art approach for imaging such structures in dynamic experiments, reconstructing a real-time nanoscale picture of the properties......-structure correlation. This paper aims at reviewing and discussing in situ TEM magnetic imaging studies, including Lorentz microscopy and electron holography in TEM, applied to the research of magnetic nanostructures....

Unpolarized Structure Functions

International Nuclear Information System (INIS)

Christy, M.E.; Melnitchouk, W.

2011-01-01

Over the past decade measurements of unpolarized structure functions with unprecedented precision have significantly advanced our knowledge of nucleon structure. These have for the first time allowed quantitative tests of the phenomenon of quark-hadron duality, and provided a deeper understanding of the transition from hadron to quark degrees of freedom in inclusive scattering. Dedicated Rosenbluth-separation experiments have yielded high-precision transverse and longitudinal structure functions in regions previously unexplored, and new techniques have enabled the first glimpses of the structure of the free neutron, without contamination from nuclear effects.

Neural correlates of emotional personality: a structural and functional magnetic resonance imaging study.

Directory of Open Access Journals (Sweden)

Stefan Koelsch

Full Text Available Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called E κ value (computed from the electrocardiogram which has previously been related to tender emotionality. Questionnaire scores and E κ values were related to both functional (eigenvector centrality mapping, ECM and structural (voxel-based morphometry, VBM neuroimaging data. Functional magnetic resonance imaging (fMRI data were obtained from 22 individuals (12 females while listening to music (joy, fear, or neutral music. ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens. Individuals with higher E κ values (indexing higher tender emotionality showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher E κ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher E κ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (E κ correlates with both function (increased network centrality and structure (grey matter volume of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for

Neural correlates of emotional personality: a structural and functional magnetic resonance imaging study.

Science.gov (United States)

Koelsch, Stefan; Skouras, Stavros; Jentschke, Sebastian

2013-01-01

Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called E κ value (computed from the electrocardiogram) which has previously been related to tender emotionality. Questionnaire scores and E κ values were related to both functional (eigenvector centrality mapping, ECM) and structural (voxel-based morphometry, VBM) neuroimaging data. Functional magnetic resonance imaging (fMRI) data were obtained from 22 individuals (12 females) while listening to music (joy, fear, or neutral music). ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens). Individuals with higher E κ values (indexing higher tender emotionality) showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females) showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher E κ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher E κ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (E κ) correlates with both function (increased network centrality) and structure (grey matter volume) of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for

Application of in situ diffraction in high-throughput structure determination platforms.

Science.gov (United States)

Aller, Pierre; Sanchez-Weatherby, Juan; Foadi, James; Winter, Graeme; Lobley, Carina M C; Axford, Danny; Ashton, Alun W; Bellini, Domenico; Brandao-Neto, Jose; Culurgioni, Simone; Douangamath, Alice; Duman, Ramona; Evans, Gwyndaf; Fisher, Stuart; Flaig, Ralf; Hall, David R; Lukacik, Petra; Mazzorana, Marco; McAuley, Katherine E; Mykhaylyk, Vitaliy; Owen, Robin L; Paterson, Neil G; Romano, Pierpaolo; Sandy, James; Sorensen, Thomas; von Delft, Frank; Wagner, Armin; Warren, Anna; Williams, Mark; Stuart, David I; Walsh, Martin A

2015-01-01

Macromolecular crystallography (MX) is the most powerful technique available to structural biologists to visualize in atomic detail the macromolecular machinery of the cell. Since the emergence of structural genomics initiatives, significant advances have been made in all key steps of the structure determination process. In particular, third-generation synchrotron sources and the application of highly automated approaches to data acquisition and analysis at these facilities have been the major factors in the rate of increase of macromolecular structures determined annually. A plethora of tools are now available to users of synchrotron beamlines to enable rapid and efficient evaluation of samples, collection of the best data, and in favorable cases structure solution in near real time. Here, we provide a short overview of the emerging use of collecting X-ray diffraction data directly from the crystallization experiment. These in situ experiments are now routinely available to users at a number of synchrotron MX beamlines. A practical guide to the use of the method on the MX suite of beamlines at Diamond Light Source is given.

In-situ real-time x-ray scattering for probing the processing-structure-performance relation

KAUST Repository

Smilgies, Detlef-M.

2014-01-01

© 2014 Materials Research Society. In-situ X-ray scattering methodology is discussed, in order to analyze the microstructure development of soft functional materials during coating, annealing, and drying processes in real-time. The relevance of a fundamental understanding of coating processes for future industrial production is pointed out.

The study of virus structure and function: a personal history

Science.gov (United States)

Rossmann, Michael G.

2014-09-01

I describe my gradually evolving role as a scientist from my birth in Frankfurt (Germany) to my education in the UK, my post-doc years and my experiences as an independent investigator at Purdue University1. I discuss the significance of my post-doctoral work in Minnesota where I had my first encounter with an electronic computer and subsequently in Cambridge where I participated in the first structure determination of proteins. After six years back in England my family moved to Indiana (USA) where my home remains to this day. At Purdue University I first studied the structure of enzymes and in the process I discovered the organization and slow evolution of protein domains, each with a specific function. With this success I started what had been on my mind already for a long time, namely the structural analysis of viruses. Initially we studied plant viruses but then switched to small RNA animal viruses, discovering that some plant and animal RNA viruses have closely similar structures and therefore presumably had a common evolutionary origin. Next I became interested in somewhat larger viruses that had lipid membrane envelopes. In turn that has led to the study of very large dsDNA viruses as big as small bacteria as well as studies of bacterial viruses that require complex molecular motors for different parts of their life cycle. While developing crystallographic techniques for the study of viruses it has become progressively more apparent that electron microscopy is an important new tool that is likely to eclipse x-ray crystallography in the next decade.

Density functional study of the electronic structure of dye-functionalized fullerenes and their model donor-acceptor complexes containing P3HT

International Nuclear Information System (INIS)

Baruah, Tunna; Garnica, Amanda; Paggen, Marina; Basurto, Luis; Zope, Rajendra R.

2016-01-01

We study the electronic structure of C 60 fullerenes functionalized with a thiophene-diketo-pyrrolopyrrole-thiophene based chromophore using density functional theory combined with large polarized basis sets. As the attached chromophore has electron donor character, the functionalization of the fullerene leads to a donor-acceptor (DA) system. We examine in detail the effect of the linker and the addition site on the electronic structure of the functionalized fullerenes. We further study the electronic structure of these DA complexes with a focus on the charge transfer excitations. Finally, we examine the interface of the functionalized fullerenes with the widely used poly(3-hexylthiophene-2,5-diyl) (P3HT) donor. Our results show that all functionalized fullerenes with an exception of the C 60 -pyrrolidine [6,6], where the pyrrolidine is attached at a [6,6] site, have larger electron affinities relative to the pristine C 60 fullerene. We also estimate the quasi-particle gap, lowest charge transfer excitation energy, and the exciton binding energies of the functionalized fullerene-P3MT model systems. Results show that the exciton binding energies in these model complexes are slightly smaller compared to a similarly prepared phenyl-C 61 -butyric acid methyl ester (PCBM)-P3MT complex.

Evaluating in situ thermal transmittance of green buildings masonries—A case study

Directory of Open Access Journals (Sweden)

Francesco Asdrubali

2014-01-01

The paper presents the results of a measurement campaign of in situ thermal transmittance, performed in some buildings in the Umbria Region (Italy, designed implementing bio-architecture solutions. The analyzed walls were previously monitored with thermographic surveys in order to assess the correct application of the sensors. Results of the investigation show that in situ thermal transmittance measurements and theoretical calculated U-value are not in perfect agreement. The mismatch becomes important for monolithic structures such as walls made of thermal blocks without insulating layers.

On The Development of Additive Construction Technologies for Application to Development of Lunar/Martian Surface Structures Using In-Situ Materials

Science.gov (United States)

Werkheiser, Niki; Fiske, Michael; Edmunson, Jennifer; Khoshnevis, Behrokh

2015-01-01

For long-duration missions on other planetary bodies, the use of in-situ materials will become increasingly critical. As man's presence on these bodies expands, so must the breadth of the structures required to accommodate them including habitats, laboratories, berms, radiation shielding for natural radiation and surface reactors, garages, solar storm shelters, greenhouses, etc. Planetary surface structure manufacturing and assembly technologies that incorporate in-situ resources provide options for autonomous, affordable, pre-positioned environments with radiation shielding features and protection from micrometeorites, exhaust plume debris, and other hazards. This is important because gamma and particle radiation constitute a serious but reducible threat to long-term survival of human beings, electronics, and other materials in space environments. Also, it is anticipated that surface structures will constitute the primary mass element of lunar or Martian launch requirements. The ability to use in-situ materials to construct these structures will provide a benefit in the reduction of up-mass that would otherwise make long-term Moon or Mars structures cost prohibitive. The ability to fabricate structures in situ brings with it the ability to repair these structures, which allows for self-sufficiency necessary for long-duration habitation. Previously, under the auspices of the MSFC In Situ Fabrication and Repair (ISFR) project and more recently, under the joint MSFC/KSC Additive Construction with Mobile Emplacement (ACME) project, the MSFC Surface Structures Group has been developing materials and construction technologies to support future planetary habitats with in situ resources. One such technology, known as Contour Crafting (additive construction), is shown in Figure 1, along with a typical structure fabricated using this technology. This paper will present the results to date of these efforts, including development of novel nozzle concepts for advanced layer

Ultrahigh-vacuum in situ electrochemistry with solid polymer electrolyte and x-ray photoelectron spectroscopy studies of polypyrrole

International Nuclear Information System (INIS)

Skotheim, T.A.; Florit, M.I.; Melo, A.; O'Grady, W.E.

1984-01-01

A new in situ combined electrochemistry and x-ray-photoelectron-spectroscopy (XPS) technique using solid polymer electrolytes has been used to characterize electrically conducting films of polypyrrole perchlorate. The technique allows in situ electrochemical oxidation and reduction (doping and undoping) in ultrahigh vacuum and the simultaneous study of the polymer with XPS as a function of its electrochemical potential. We demonstrate that some anion species interact strongly electrostatically with the nitrogen heteroatoms. We also show conclusively that the electrochemistry of polypyrrole is highly irreversible

In situ and ex situ modifications of bacterial cellulose for applications in tissue engineering.

Science.gov (United States)

Stumpf, Taisa Regina; Yang, Xiuying; Zhang, Jingchang; Cao, Xudong

2018-01-01

Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use as a biomaterial for scaffolds in tissue engineering. To extend its applications in tissue engineering, native BC is normally modified to enhance its properties. Generally, BC modifications can be made by either in situ modification during cell culture or ex situ modification of existing BC microfibers. In this review we will first provide a brief introduction of BC and its attributes; this will set the stage for in-depth and up-to-date discussions on modified BC. Finally, the review will focus on in situ and ex situ modifications of BC and its applications in tissue engineering, particularly in bone regeneration and wound dressing. Copyright © 2016. Published by Elsevier B.V.

Metagenomics insights into Cr(VI effects on structural and functional diversity of bacterial community in chromite mine soils of Sukinda Valley, Odisha

Directory of Open Access Journals (Sweden)

Sukanta Kumar Pradhan

2017-12-01

Full Text Available Soil contamination with heavy metal like chromium is a wide-spread environmental problem in mining and its periphery areas causing hazard to the plant, animal and human. Bacterial communities which resist the toxic effect of Cr(VI can only survive under this hostile condition. In the study assessment of structural diversity of bacterial communities from four different locations of chromite mines area of Sukinda, Odisha (India were carried out with 16S rRNA amplicon sequencing of V3 regions using illuminaMiSeq and functional diversity analysis from in situ mining site with whole genome metagenomics using illuminaHiSeq. The taxonomic classification was carried out through QIIME program. The samples differed from each other, both in terms of level of contamination and soil characteristics. The variations in pH were small (6.67-7.32 between the mine soils from in situ and overburden sites in comparison to forest soil (5.08. The forest soil contains higher amount of available N and K as well as organic carbon as compared to both the mine soils. Heavy metals like Fe, Cr, Ni, and Cd have been detected in higher concentrations in in situ sites than both overburden and forest soil samples. Whereas concentration of other heavy metals like Co and Mn is high in overburden than in situ and forest soil. In spite of the differences between the samples, they shared many common operational taxonomic units (OTUs and it was possible to delineate the core microbiome of the soil samples. In general, Actinobacteria were the most dominant phyla with abundance of Deltaproteobacteria, Alphaproteobacteria, and Gammaproteobacteria within the soils. Certain bacterial genera like Acinetobacter, Pseudomonas, Lactobacillus, Bacillus, Clostridium and Corynebacterium were found to be predominant in in situ mining sites, whereas genera like Nitrospira, DA101, JG37-AG-70 and Nitrospira and DA101 were found to be abundant in overburden and forest soil respectively. In in situ soil

In situ synchrotron X-ray diffraction study on epitaxial-growth dynamics of III–V semiconductors

Science.gov (United States)

Takahasi, Masamitu

2018-05-01

The application of in situ synchrotron X-ray diffraction (XRD) to the molecular-beam epitaxial (MBE) growth of III–V semiconductors is overviewed along with backgrounds of the diffraction theory and instrumentation. X-rays are sensitive not only to the surface of growing films but also to buried interfacial structures because of their large penetration depth. Moreover, a spatial coherence length up to µm order makes X-rays widely applicable to the characterization of low-dimensional structures, such as quantum dots and wires. In situ XRD studies during growth were performed using an X-ray diffractometer, which was combined with an MBE chamber. X-ray reciprocal space mapping at a speed matching a typical growth rate was achieved using intense X-rays available from a synchrotron light source and an area detector. The importance of measuring the three-dimensional distribution of XRD intensity in a reciprocal space map is demonstrated for the MBE growth of two-, one-, and zero-dimensional structures. A large amount of information about the growth process of two-dimensional InGaAs/GaAs(001) epitaxial films has been provided by three-dimensional X-ray reciprocal mappings, including the anisotropic strain relaxation, the compositional inhomogeneity, and the evolution of surface and interfacial roughness. For one-dimensional GaAs nanowires grown in a Au-catalyzed vapor-liquid–solid mode, the relationship between the diameter of the nanowires and the formation of polytypes has been suggested on the basis of in situ XRD measurements. In situ three-dimensional X-ray reciprocal space mapping is also shown to be useful for determining the lateral and vertical sizes of self-assembled InAs/GaAs(001) quantum dots as well as their internal strain distributions during growth.

Structural and functional responses of benthic invertebrates to imidacloprid in outdoor stream mesocosms

International Nuclear Information System (INIS)

Pestana, J.L.T.; Alexander, A.C.; Culp, J.M.; Baird, D.J.; Cessna, A.J.; Soares, A.M.V.M.

2009-01-01

Structural and functional responses of a benthic macroinvertebrate assemblage to pulses of the insecticide imidacloprid were assessed in outdoor stream mesocosms. Imidacloprid pulses reduced invertebrate abundance and community diversity in imidacloprid-dosed streams compared to control streams. These results correlated well with effects of imidacloprid on leaf litter decomposition and feeding rates of Pteronarcys comstocki, a stonefly, in artificial streams. Reductions in oxygen consumption of stoneflies exposed to imidacloprid were also observed in laboratory experiments. Our findings suggest that leaf litter degradation and single species responses can be sensitive ecotoxicological endpoints that can be used as early warning indicators and biomonitoring tools for pesticide contamination. The data generated illustrates the value of mesocosm experiments in environmental assessment and how the consideration of functional and structural endpoints of natural communities together with in situ single species bioassays can improve the evaluation and prediction of pesticide effects on stream ecosystems. - Combining organism-level responses with community-level processes for the evaluation and prediction of pesticide effects on stream ecosystems.

Structural and functional responses of benthic invertebrates to imidacloprid in outdoor stream mesocosms

Energy Technology Data Exchange (ETDEWEB)

Pestana, J.L.T., E-mail: jpestana@ua.p [CESAM and Departamento de Biologia, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Environment Canada at Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB (Canada); Alexander, A.C., E-mail: alexa.alexander@unb.c [Environment Canada at Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB (Canada); Culp, J.M., E-mail: jculp@unb.c [Environment Canada at Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB (Canada); Baird, D.J., E-mail: djbaird@unb.c [Environment Canada at Canadian Rivers Institute, Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB (Canada); Cessna, A.J., E-mail: asoares@ua.p [Environment Canada, National Hydrology Research Centre, 11 Innovation Boulevard, Saskatoon, SK (Canada); Soares, A.M.V.M., E-mail: asoares@ua.p [CESAM and Departamento de Biologia, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

2009-08-15

Structural and functional responses of a benthic macroinvertebrate assemblage to pulses of the insecticide imidacloprid were assessed in outdoor stream mesocosms. Imidacloprid pulses reduced invertebrate abundance and community diversity in imidacloprid-dosed streams compared to control streams. These results correlated well with effects of imidacloprid on leaf litter decomposition and feeding rates of Pteronarcys comstocki, a stonefly, in artificial streams. Reductions in oxygen consumption of stoneflies exposed to imidacloprid were also observed in laboratory experiments. Our findings suggest that leaf litter degradation and single species responses can be sensitive ecotoxicological endpoints that can be used as early warning indicators and biomonitoring tools for pesticide contamination. The data generated illustrates the value of mesocosm experiments in environmental assessment and how the consideration of functional and structural endpoints of natural communities together with in situ single species bioassays can improve the evaluation and prediction of pesticide effects on stream ecosystems. - Combining organism-level responses with community-level processes for the evaluation and prediction of pesticide effects on stream ecosystems.

The structure of phosphate and borosilicate glasses and their structural evolution at high temperatures as studied with solid state NMR spectroscopy: Phase separation, crystallisation and dynamic species exchange

International Nuclear Information System (INIS)

Wegner, S.; Van Wullen, L.; Tricot, G.; Tricot, G.

2010-01-01

In this contribution we present an in-depth study of the network structure of different phosphate based and borosilicate glasses and its evolution at high temperatures. Employing a range of advanced solid state NMR methodologies, complemented by the results of XPS, the structural motifs on short and intermediate length scales are identified. For the phosphate based glasses, at temperatures above the glass transition temperature Tg, structural relaxation processes and the devitrification of the glasses were monitored in situ employing MAS NMR spectroscopy and X-ray diffraction. Dynamic species exchange involving rapid P-O-P and P-O-Al bond breaking and reforming was observed employing in situ 27 Al and 31 P MAS NMR spectroscopy and could be linked to viscous flow. For the borosilicate glasses, an atomic scale investigation of the phase separation processes was possible in a combined effort of ex situ NMR studies on glass samples with different thermal histories and in situ NMR studies using high temperature MAS NMR spectroscopy including 11 B MAS, 29 Si MAS and in situ 29 Si{ 11 B} REAPDOR NMR spectroscopy. (authors)

Recent density functional studies of hydrodesulfurization catalysts: insight into structure and mechanism

International Nuclear Information System (INIS)

Hinnemann, Berit; Moses, Poul Georg; Noerskov, Jens K

2008-01-01

The present article will highlight some recent density functional theory (DFT) studies of hydrodesulfurization (HDS) catalysts. It will be summarized how DFT in combination with experimental studies can give a detailed picture of the structure of the active phase. Furthermore, we have used DFT to investigate the reaction pathway for thiophene HDS, and we find that the reaction entails a complex interplay of different active sites, depending on reaction conditions. An investigation of pyridine inhibition confirmed some of these results. These fundamental insights constitute a basis for rational improvement of HDS catalysts, as they have provided important structure-activity relationships

In Situ Live-Cell Nucleus Fluorescence Labeling with Bioinspired Fluorescent Probes.

Science.gov (United States)

Ding, Pan; Wang, Houyu; Song, Bin; Ji, Xiaoyuan; Su, Yuanyuan; He, Yao

2017-08-01

Fluorescent imaging techniques for visualization of nuclear structure and function in live cells are fundamentally important for exploring major cellular events. The ideal cellular labeling method is capable of realizing label-free, in situ, real-time, and long-term nucleus labeling in live cells, which can fully obtain the nucleus-relative information and effectively alleviate negative effects of alien probes on cellular metabolism. However, current established fluorescent probes-based strategies (e.g., fluorescent proteins-, organic dyes-, fluorescent organic/inorganic nanoparticles-based imaging techniques) are unable to simultaneously realize label-free, in situ, long-term, and real-time nucleus labeling, resulting in inevitable difficulties in fully visualizing nuclear structure and function in live cells. To this end, we present a type of bioinspired fluorescent probes, which are highly efficacious for in situ and label-free tracking of nucleus in long-term and real-time manners. Typically, the bioinspired polydopamine (PDA) nanoparticles, served as fluorescent probes, can be readily synthesized in situ within live cell nucleus without any further modifications under physiological conditions (37 °C, pH ∼7.4). Compared with other conventional nuclear dyes (e.g., propidium iodide (PI), Hoechst), superior spectroscopic properties (e.g., quantum yield of ∼35.8% and high photostability) and low cytotoxicity of PDA-based probes enable long-term (e.g., 3 h) fluorescence tracking of nucleus. We also demonstrate the generality of this type of bioinspired fluorescent probes in different cell lines and complex biological samples.

In situ single molecule imaging of cell membranes: linking basic nanotechniques to cell biology, immunology and medicine

Science.gov (United States)

Pi, Jiang; Jin, Hua; Yang, Fen; Chen, Zheng W.; Cai, Jiye

2014-10-01

The cell membrane, which consists of a viscous phospholipid bilayer, different kinds of proteins and various nano/micrometer-sized domains, plays a very important role in ensuring the stability of the intracellular environment and the order of cellular signal transductions. Exploring the precise cell membrane structure and detailed functions of the biomolecules in a cell membrane would be helpful to understand the underlying mechanisms involved in cell membrane signal transductions, which could further benefit research into cell biology, immunology and medicine. The detection of membrane biomolecules at the single molecule level can provide some subtle information about the molecular structure and the functions of the cell membrane. In particular, information obtained about the molecular mechanisms and other information at the single molecule level are significantly different from that detected from a large amount of biomolecules at the large-scale through traditional techniques, and can thus provide a novel perspective for the study of cell membrane structures and functions. However, the precise investigations of membrane biomolecules prompts researchers to explore cell membranes at the single molecule level by the use of in situ imaging methods, as the exact conformation and functions of biomolecules are highly controlled by the native cellular environment. Recently, the in situ single molecule imaging of cell membranes has attracted increasing attention from cell biologists and immunologists. The size of biomolecules and their clusters on the cell surface are set at the nanoscale, which makes it mandatory to use high- and super-resolution imaging techniques to realize the in situ single molecule imaging of cell membranes. In the past few decades, some amazing imaging techniques and instruments with super resolution have been widely developed for molecule imaging, which can also be further employed for the in situ single molecule imaging of cell membranes. In

A economic evaluation system software on in-situ leaching mining sandstone uranium deposits

International Nuclear Information System (INIS)

Yao Yixuan; Su Xuebin; Xie Weixing; Que Weimin

2001-01-01

The author presents the study results of applying computer technology to evaluate quantitatively the technical-economic feasibility of in-situ leaching mining sandstone uranium deposits. A computer system software have been developed. Under specifying deposit conditions and given production size per year, the application of the software will generate total capital and mine life operating costs as well as solve for the movable and static financial assessment targets through discounted cash flow analysis. According to the characters of two kinds of sandstone uranium deposits, a data bases of economic and technique parameters of in-situ leaching have been designed. Also the system software can be used to study the economic value of deposits and to optimize the key project parameters. Its features, data input method and demand, main functions, structure and operating environments are described

Study on the fabrication of Al matrix composites strengthened by combined in-situ alumina particle and in-situ alloying elements

International Nuclear Information System (INIS)

Huang Zanjun; Yang Bin; Cui Hua; Zhang Jishan

2003-01-01

A new idea to fabricate aluminum matrix composites strengthened by combined in-situ particle strengthening and in-situ alloying has been proposed. Following the concept of in-situ alloying and in-situ particle strengthening, aluminum matrix composites reinforced by Cu and α-Al 2 O 3 particulate (material I) and the same matrix reinforced by Cu, Si alloying elements and α-Al 2 O 3 particulate (material II) have been obtained. SEM observation, EDS and XRD analysis show that the alloy elements Cu and Si exist in the two materials, respectively. In-situ Al 2 O 3 particulates are generally spherical and their mean size is less than 0.5 μm. TEM observation shows that the in-situ α-Al 2 O 3 particulates have a good cohesion with the matrix. The reaction mechanism of the Al 2 O 3 particulate obtained by this method was studied. Thermodynamic considerations are given to the in-situ reactions and the distribution characteristic of in-situ the α-Al 2 O 3 particulate in the process of solidification is also discussed

Electrochemical studies, in-situ and ex-situ characterizations of different manganese compounds electrodeposited in aerated solutions

International Nuclear Information System (INIS)

Peulon, S.; Lacroix, A.; Chausse, A.; Larabi-Gruet, N.

2007-01-01

This work deals with the electrodeposition of manganese compounds. A systematic study of the synthesis experimental conditions has been carried out, and the obtained depositions have been characterized by different ex-situ analyses methods (XRD, FTIR, SEM). The in-situ measurements of mass increase with a quartz microbalance during the syntheses have allowed to estimate the growth mechanisms which are in agreement with the ex-situ characterizations. The cation has an important role in the nature of the electrodeposited compounds. In presence of sodium, a mixed lamellar compound Mn(III)/Mn(IV), the birnessite, is deposited, whereas in presence of potassium, bixbyite is formed (Mn 2 O 3 ), these two compounds having a main role in the environment. The substrate can also influence the nature of the formed intermediary compounds. Little studied compounds such as feitkneichtite (β-MnOOH) and groutite (α-MnOOH) have been revealed. (O.M.)

Planning, developing, and fielding of thermal/structural interactions in situ tests for the Waste Isolation Pilot Plant (WIPP)

International Nuclear Information System (INIS)

Munson, D.E.; Matalucci, R.V.

1986-01-01

Large-scale, well-instrumented underground tests to determine in situ thermal/structural response of bedded salt are being constructed in the WIPP facility in southeastern New Mexico. These tests are an essential component of a broad research and development program to resolve thermal/structural issues, to validate long-term prediction methods, and to develop a design basis for a future repository. They are the result of an extensive planning and evaluation procedure to determine the appropriate test configuration. All details of the tests, including background, decisions, design, site operations, and testing organization are explained. These procedures may be useful in developing other in situ tests

Clustering aspects in nuclear structure functions

International Nuclear Information System (INIS)

Hirai, M.; Saito, K.; Watanabe, T.; Kumano, S.

2011-01-01

For understanding an anomalous nuclear effect experimentally observed for the beryllium-9 nucleus at the Thomas Jefferson National Accelerator Facility, clustering aspects are studied in structure functions of deep inelastic lepton-nucleus scattering by using momentum distributions calculated in antisymmetrized (or fermionic) molecular dynamics (AMD) and also in a simple shell model for comparison. According to AMD, the 9 Be nucleus consists of two α-like clusters with a surrounding neutron. The clustering produces high-momentum components in nuclear wave functions, which affects nuclear modifications of the structure functions. We investigated whether clustering features could appear in the structure function F 2 of 9 Be along with studies for other light nuclei. We found that nuclear modifications of F 2 are similar in both AMD and shell models within our simple convolution description although there are slight differences in 9 Be. It indicates that the anomalous 9 Be result should be explained by a different mechanism from the nuclear binding and Fermi motion. If nuclear-modification slopes d(F 2 A /F 2 D )/dx are shown by the maximum local densities, the 9 Be anomaly can be explained by the AMD picture, namely by the clustering structure, whereas it certainly cannot be described in the simple shell model. This fact suggests that the large nuclear modification in 9 Be should be explained by large densities in the clusters. For example, internal nucleon structure could be modified in the high-density clusters. The clustering aspect of nuclear structure functions is an unexplored topic which is interesting for future investigations.

Multiphoton microscopy: an efficient tool for in-situ study of cultural heritage artifacts

Science.gov (United States)

Latour, Gaël.; Echard, Jean-Philippe; Didier, Marie; Schanne-Klein, Marie-Claire

2013-05-01

We present multimodal nonlinear optical imaging of historical artifacts by combining Two-Photon Excited Fluorescence (2PEF) and Second Harmonic Generation (SHG) microscopies. Three-dimensional (3D) non-contact laser-scanning imaging with micrometer resolution is performed without any preparation of the objects under study. 2PEF signals are emitted by a wide range of fluorophores such as pigments and binder, which can be discriminated thanks to their different emission spectral bands by using suitable spectral filters in the detection channel. SHG signals are specific for dense non-centrosymmetric organizations such as the crystalline cellulose within the wood cell walls. We also show that plaster particles exhibit SHG signals. These particles are bassanite crystals with a non-centrosymmetric crystalline structure, while the other types of calcium sulphates exhibit a centrosymmetric crystalline structure with no SHG signal. In our study, we first characterize model single-layered samples: wood, gelatin-based films containing plaster or cochineal lake and sandarac film containing cochineal lake. We then study multilayered coating systems on wood and show that multimodal nonlinear microscopy successfully reveals the 3D distribution of all components within the stratified sample. We also show that the fine structure of the wood can be assessed, even through a thick multilayered varnish coating. Finally, in situ multimodal nonlinear imaging is demonstrated in a historical violin. SHG/2PEF imaging thus appears as an efficient non-destructive and contactless 3D imaging technique for in situ investigation of historical coatings and more generally for wood characterization and coating analysis at micrometer scale.

Study of the hadronic photon structure function $F^\\gamma_2$ at LEP

CERN Document Server

Acciarri, M; Aguilar-Benítez, M; Ahlen, S P; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Baksay, L; Ball, R C; Banerjee, S; Banerjee, Sw; Banicz, K; Barczyk, A; Barillère, R; Barone, L; Bartalini, P; Baschirotto, A; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Bilei, G M; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böck, R K; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Boutigny, D; Braccini, S; Branson, J G; Brigljevic, V; Brock, I C; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Busenitz, J K; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chen, M; Chiefari, G; Chien, C Y; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colijn, A P; Colino, N; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Dai, T S; D'Alessandro, R; De Asmundis, R; Degré, A; Deiters, K; Denes, P; De Notaristefani, F; Diemoz, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Drago, E; Duchesneau, D; Duinker, P; Durán, I; Easo, S; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ernenwein, J P; Extermann, Pierre; Fabre, M; Faccini, R; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Fredj, L; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gerald, J; Gheordanescu, N; Giagu, S; Goldfarb, S; Goldstein, J; Gong, Z F; Gougas, Andreas; Gratta, Giorgio; Grünewald, M W; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hartmann, B; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Van Hoek, W C; Hofer, H; Hoorani, H; Hou, S R; Hu, G; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Kasser, A; Khan, R A; Kamrad, D; Kapustinsky, J S; Karyotakis, Yu; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, D H; Kim, J K; Kim, S C; Kinnison, W W; Kirkby, A; Kirkby, D; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopp, A; Korolko, I; Koutsenko, V F; Krämer, R W; Krenz, W; Kunin, A; Lacentre, P E; Ladrón de Guevara, P; Landi, G; Lapoint, C; Lassila-Perini, K M; Laurikainen, P; Lavorato, A; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Leggett, C; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lu, W; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Majumder, G; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Marchesini, P A; Marian, G; Marin, A; Martin, J P; Marzano, F; Massaro, G G G; Mazumdar, K; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mi, Y; Migani, D; Mihul, A; Van Mil, A J W; Milcent, H; Mirabelli, G; Mnich, J; Molnár, P; Monteleoni, B; Moore, R; Moulik, T; Mount, R; Muheim, F; Muijs, A J M; Nahn, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nippe, A; Nisati, A; Nowak, H; Oh, Yu D; Organtini, G; Ostonen, R; Palit, S; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Park, H K; Park, I H; Pascale, G; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Peach, D; Pei, Y J; Pensotti, S; Perret-Gallix, D; Petersen, B; Petrak, S; Pevsner, A; Piccolo, D; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Produit, N; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Raja, N; Rancoita, P G; Rattaggi, M; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Van Rhee, T; Riemann, S; Riles, K; Rind, O; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosier-Lees, S; Rosselet, P; Roth, S; Rubio, Juan Antonio; Ruschmeier, D; Rykaczewski, H; Salicio, J; Sánchez, E; Sanders, M P; Sarakinos, M E; Sauvage, G; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schneegans, M; Scholz, N; Schopper, Herwig Franz; Schotanus, D J; Schwenke, J; Schwering, G; Sciacca, C; Sciarrino, D; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shukla, J; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Soulimov, V; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, H; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Susinno, G F; Suter, H; Swain, J D; Tang, X W; Tauscher, Ludwig; Taylor, L; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Viertel, Gert M; Vivargent, M; Vlachos, S; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, J C; Wang, X L; Wang, Z M; Weber, A; Wu, S X; Wynhoff, S; Xu, J; Xu, Z Z; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Ye, J B; Yeh, S C; You, J M; Zalite, A; Zalite, Yu; Zemp, P; Zeng, Y; Zhang, Z P; Zhou, B; Zhou, Y; Zhu, G Y; Zhu, R Y; Zichichi, Antonino; Ziegler, F; Zilizi, G

1998-01-01

The hadronic photon structure function $F^\\gamma_2$ is studied in the reaction $\\mathrm{e^+e^-} \\rightarrow \\mathrm{e^+e^-hadrons}$ at LEP with the L3 detector. The data, collected from 1991 to 1995 at a centre-of-mass energy $\\sqrt{s} \\simeq 91 \\GeV$, correspond to an integrated luminosity of 140~pb$^{-1}$. The photon structure function $F^\\gamma_2$ is measured in the $Q^2$ interval $1.2 \\GeV^2 \\leq Q^2 \\leq 9.0 \\GeV^2$ and the $x$ interval $0.002 < x < 0.2$. $\\FF$ shows a linear growth with $\\ln Q^2$. The value of the slope $\\alpha^{-1}\\mathrm{d}\\FF(Q^2)/\\mathrm{d}\\ln{Q^2}$ is measured to be $0.079 \\pm 0.011 \\pm 0.009$.

In-situ, real-time, studies of film growth processes using ion scattering and direct recoil spectroscopy techniques.

Energy Technology Data Exchange (ETDEWEB)

Smentkowski, V. S.

1999-04-22

Time-of-flight ion scattering and recoil spectroscopy (TOF-ISARS) enables the characterization of the composition and structure of surfaces with 1-2 monolayer specificity. It will be shown that surface analysis is possible at ambient pressures greater than 3 mTorr using TOF-ISARS techniques; allowing for real-time, in situ studies of film growth processes. TOF-ISARS comprises three analytical techniques: ion scattering spectroscopy (ISS), which detects the backscattered primary ion beam; direct recoil spectroscopy (DRS), which detects the surface species recoiled into the forward scattering direction; and mass spectroscopy of recoiled ions (MSRI), which is 3 variant of DRS capable of isotopic resolution for all surface species--including H and He. The advantages and limitations of each of these techniques will be discussed. The use of the three TOF-ISARS methods for real-time, in situ film growth studies at high ambient pressures will be illustrated. It will be shown that MSRI analysis is possible during sputter deposition. It will be also be demonstrated that the analyzer used for MSRI can also be used for time of flight secondary ion mass spectroscopy (TOF-SIMS) under high vacuum conditions. The use of a single analyzer to perform the complimentary surface analytical techniques of MSRI and SIMS is unique. The dwd functionality of the MSRI analyzer provides surface information not obtained when either MSRI or SIMS is used independently.

In-Situ Studies of Structure Transformation and Al Coordination of KAl(MoO42 during Heating by High Temperature Raman and 27Al NMR Spectroscopies

Directory of Open Access Journals (Sweden)

Min Wang

2017-03-01

Full Text Available Recent interest in optimizing composition and synthesis conditions of functional crystals, and the further exploration of new possible candidates for tunable solid-state lasers, has led to significant research on compounds in this family MIMIII(MVIO42 (MI = alkali metal, MIII = Al, In, Sc, Fe, Bi, lanthanide; MVI = Mo, W. The vibrational modes, structure transformation, and Al coordination of crystalline, glassy, and molten states of KAl(MoO42 have been investigated by in-situ high temperature Raman scattering and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR spectroscopy, together with first principles density functional simulation of room temperature Raman spectrum. The results showed that, under the present fast quenching conditions, Al is present predominantly in [AlO6] octahedra in both KAl(MoO42 glass and melt, with the tetrahedrally coordinated Al being minor at approximately 2.7%. The effect of K+, from ordered arrangement in the crystal to random distribution in the melt, on the local chemical environment of Al, was also revealed. The distribution and quantitative analysis of different Al coordination subspecies are final discussed and found to be dependent on the thermal history of the glass samples.

Structural study on the gas adsorption phenomena in porous coordination polymers by synchrotron powder diffraction method

International Nuclear Information System (INIS)

Kubota, Yoshiki

2017-01-01

In situ synchrotron powder diffraction measurement of gas adsorption and crystal structure analysis for porous coordination polymers (PCPs) were performed. From the obtained accurate crystal structure in both atomic and charge density levels, not only the position and orientation of adsorbed gas molecules but also the interaction between the adsorbed gas molecule and host framework were found. The information enables us to understand the mechanism of gas adsorption phenomena and functions of PCPs. It will give us the guiding principles for the novel functional materials design. (author)

In situ degradation studies of two-dimensional WSe₂-graphene heterostructures.

Science.gov (United States)

Wang, B; Eichfield, S M; Wang, D; Robinson, J A; Haque, M A

2015-09-14

Heterostructures of two-dimensional materials can be vulnerable to thermal degradation due to structural and interfacial defects as well as thermal expansion mismatch, yet a systematic study does not exist in the literature. In this study, we investigate the degradation of freestanding WSe2-graphene heterostructures due to heat and charge flow by performing in situ experiments inside a transmission electron microscope. Experimental results show that purely thermal loading requires higher temperatures (>850 °C), about 150 °C higher than that under combined electrical and thermal loading. In both cases, selenium is the first element to decompose and migration of silicon atoms from the test structure to the freestanding specimen initiates rapid degradation through the formation of tungsten disilicide and silicon carbide. The role of the current flow is to enhance the migration of silicon from the sample holder and to knock-out the selenium atoms. The findings of this study provide fundamental insights into the degradation of WSe2-graphene heterostructures and inspire their application in electronics for use in harsh environments.

Sphingomyelinase D activity in model membranes: structural effects of in situ generation of ceramide-1-phosphate

DEFF Research Database (Denmark)

Stock, Roberto; Brewer, Jonathan R.; Wagner, Kerstin

2012-01-01

The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model...... membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy...... and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing...

In Situ Preparation of Polyether Amine Functionalized MWCNT Nanofiller as Reinforcing Agents

Directory of Open Access Journals (Sweden)

Ayber Yıldrım

2014-01-01

Full Text Available In situ preparation of polyether amine functionalized cross-linked multiwalled carbon nanotube (MWCNT nanofillers may improve the thermal and mechanical properties of the composites in which they are used as reinforcing agents. The reduction and functionalization of MWCNT using ethylenediamine in the presence of polyether amine produced stitched MWCNT's due to the presence of two amine (–NH2 functionalities on both sides of the polymer. Polyether amine was chosen to polymerize the carboxylated MWCNT due to its potential to form bonds with the amino groups and carboxyl groups of MWCNT which produces a resin used as polymeric matrix for nanocomposite materials. The attachment of the polyether amine (Jeffamine groups was verified by TGA, FT-IR, XRD, SEM, and Raman spectroscopy. The temperature at which the curing enthalpy is maximum, observed by DSC, was shifted to higher values by adding functionalized MWCNT. SEM images show the polymer formation between MWCNT sheets.

Understanding the Thermal Stability of Palladium-Platinum Core-Shell Nanocrystals by In Situ Transmission Electron Microscopy and Density Functional Theory.

Science.gov (United States)

Vara, Madeline; Roling, Luke T; Wang, Xue; Elnabawy, Ahmed O; Hood, Zachary D; Chi, Miaofang; Mavrikakis, Manos; Xia, Younan

2017-05-23

Core-shell nanocrystals offer many advantages for heterogeneous catalysis, including precise control over both the surface structure and composition, as well as reduction in loading for rare and costly metals. Although many catalytic processes are operated at elevated temperatures, the adverse impacts of heating on the shape and structure of core-shell nanocrystals are yet to be understood. In this work, we used ex situ heating experiments to demonstrate that Pd@Pt 4L core-shell nanoscale cubes and octahedra are promising for catalytic applications at temperatures up to 400 °C. We also used in situ transmission electron microscopy to monitor the thermal stability of the core-shell nanocrystals in real time. Our results demonstrate a facet dependence for the thermal stability in terms of shape and composition. Specifically, the cubes enclosed by {100} facets readily deform shape at a temperature 300 °C lower than that of the octahedral counterparts enclosed by {111} facets. A reversed trend is observed for composition, as alloying between the Pd core and the Pt shell of an octahedron occurs at a temperature 200 °C lower than that for the cubic counterpart. Density functional theory calculations provide atomic-level explanations for the experimentally observed behaviors, demonstrating that the barriers for edge reconstruction determine the relative ease of shape deformation for cubes compared to octahedra. The opposite trend for alloying of the core-shell structure can be attributed to a higher propensity for subsurface Pt vacancy formation in octahedra than in cubes.

In-Situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes

Science.gov (United States)

2010-12-28

DATES COVERED (From - To) 1/29/10-9/30/10 4. TITLE AND SUBTITLE In situ optical studies of oxidation/reduction kinetics on SOFC cermet anodes 5a...0572 In-situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes Department of Chemistry and Biochemistry Montana State University...of Research In-situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes Principal Investigator Robert Walker Organization

Low Temperature Regolith Bricks for In-Situ Structural Material

Science.gov (United States)

Grossman, Kevin; Sakthivel, Tamil S.; Mantovani, James; Seal, Sudipta

2016-01-01

Current technology for producing in-situ structural materials on future missions to Mars or the moon relies heavily on energy-intensive sintering processes to produce solid bricks from regolith. This process requires heating the material up to temperatures in excess of 1000 C and results in solid regolith pieces with compressive strengths in the range of 14000 to 28000 psi, but are heavily dependent on the porosity of the final material and are brittle. This method is currently preferred over a low temperature cementation process to prevent consumption of precious water and other non-renewable materials. A high strength structural material with low energy requirements is still needed for future colonization of other planets. To fulfill these requirements, a nano-functionalization process has been developed to produce structural bricks from regolith simulant and shows promising mechanical strength results. Functionalization of granular silicate particles into alkoxides using a simple low temperature chemical process produces a high surface area zeolite particles that are held together via inter-particle oxygen bonding. Addition of water in the resulting zeolite particles produces a sol-gel reaction called "inorganic polymerization" which gives a strong solid material after a curing process at 60 C. The aqueous solution by-product of the reaction is currently being investigated for its reusability; an essential component of any ISRU technology. For this study, two batches of regolith bricks are synthesized from JSC-1A; the first batch from fresh solvents and chemicals, the second batch made from the water solution by-product of the first batch. This is done to determine the feasibility of recycling necessary components of the synthesis process, mainly water. Characterization including BET surface area, SEM, and EDS has been done on the regolith bricks as well as the constituent particles,. The specific surface area of 17.53 sq m/g (average) of the granular regolith

Network structure shapes spontaneous functional connectivity dynamics.

Science.gov (United States)

Shen, Kelly; Hutchison, R Matthew; Bezgin, Gleb; Everling, Stefan; McIntosh, Anthony R

2015-04-08

The structural organization of the brain constrains the range of interactions between different regions and shapes ongoing information processing. Therefore, it is expected that large-scale dynamic functional connectivity (FC) patterns, a surrogate measure of coordination between brain regions, will be closely tied to the fiber pathways that form the underlying structural network. Here, we empirically examined the influence of network structure on FC dynamics by comparing resting-state FC (rsFC) obtained using BOLD-fMRI in macaques (Macaca fascicularis) to structural connectivity derived from macaque axonal tract tracing studies. Consistent with predictions from simulation studies, the correspondence between rsFC and structural connectivity increased as the sample duration increased. Regions with reciprocal structural connections showed the most stable rsFC across time. The data suggest that the transient nature of FC is in part dependent on direct underlying structural connections, but also that dynamic coordination can occur via polysynaptic pathways. Temporal stability was found to be dependent on structural topology, with functional connections within the rich-club core exhibiting the greatest stability over time. We discuss these findings in light of highly variable functional hubs. The results further elucidate how large-scale dynamic functional coordination exists within a fixed structural architecture. Copyright © 2015 the authors 0270-6474/15/355579-10$15.00/0.

Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy

OpenAIRE

Jin-Rong Zhong; Xin-Yang Zeng; Feng-He Zhou; Qi-Dong Ran; Chang-Yu Sun; Rui-Qin Zhong; Lan-Ying Yang; Guang-Jin Chen; Carolyn A. Koh

2016-01-01

The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15?K), as determined by the stable C-H region Raman peaks and A L/A S value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to sm...

In Situ Observation of the Dislocation Structure Evolution During a Strain Path Change in Copper

DEFF Research Database (Denmark)

Wejdemann, Christian; Poulsen, Henning Friis; Lienert, Ulrich

2013-01-01

The evolution of deformation structures in individual grains embedded in polycrystalline copper specimens during strain path changes is observed in situ by high-resolution reciprocal space mapping with high-energy synchrotron radiation. A large number of individual subgrains is resolved; their be......The evolution of deformation structures in individual grains embedded in polycrystalline copper specimens during strain path changes is observed in situ by high-resolution reciprocal space mapping with high-energy synchrotron radiation. A large number of individual subgrains is resolved...... and orientation of the resolved subgrains change only slightly, while their elastic stresses are significantly altered. This indicates the existence of a microplastic regime during which only the subgrains deform plastically and no yielding of the dislocation walls occurs. After reloading above 0.3% strain......, the elastic stresses of individual subgrains are about the same as in unidirectionally deformed reference specimens. They increase only slightly during further straining—accompanied by occasional emergence of new subgrains, abundant orientation changes, and disappearance of existing subgrains....

Groundbreaking technology: in-situ anaerobic bioremediation for treatment of contaminated soil and groundwater

International Nuclear Information System (INIS)

Fernandes, K.A.

2002-01-01

Anaerobic in-situ bioremediation is a technique often used to cleanse contaminated soil and groundwater. 'Anaerobic in-situ bioremediation' is a phrase with distinct terms all having relevance in the application of this technique. Anaerobic implies the absence of dissolved oxygen, while 'in-situ' simply means that the environmental cleansing occurs with out removing, displacing, or significantly disturbing the specimen or surrounding area. 'Bioremediation' is a term used to describe the biological use of microbes or plants to detoxify the environment. In order to properly implement this complex process, one must have an understanding of microbiology, biochemistry, genetics, metabolic processes, and structure and function of natural microbial communities. (author)

In situ visualization of Ni-Nb bulk metallic glasses phase transition

OpenAIRE

Oreshkin, A. I.; Mantsevich, V. N.; Savinov, S. V.; Oreshkin, S. I.; Panov, V. I.; Yavari, A. R.; Miracle, D. B.; Louzguine-Luzgin, D. V.

2013-01-01

We report the results of the Ni-based bulk metallic glass structural evolution and crystallization behavior in situ investigation. The X-ray diffraction (XRD), transmission electron microscopy (TEM), nano-beam diffraction (NBD), differential scanning calorimetry (DSC), radial distribution function (RDF) and scanning probe microscopy/spectroscopy (STM/STS) techniques were applied to analyze the structure and electronic properties of Ni63.5Nb36.5 glasses before and after crystallization. It was...

In situ investigation of formation of self-assembled nanodomain structure in lithium niobate after pulse laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Shur, V. Ya.; Kuznetsov, D. K.; Mingaliev, E. A.; Yakunina, E. M.; Lobov, A. I.; Ievlev, A. V. [Ferroelectric Laboratory, Institute of Physics and Applied Mathematics, Ural State University, Lenin Ave. 51, Ekaterinburg 620083 (Russian Federation)

2011-08-22

The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation was studied by in situ optical observation. The average periods of the structures are much less than the sizes of the laser spots. The polarization reversal occurs through covering of the whole irradiated area by the nets of the spatially separated nanodomain chains and microdomain rays--''hatching effect.'' The main stages of the anisotropic nanodomain kinetics: nucleation, growth, and branching, have been singled out. The observed abnormal domain kinetics was attributed to the action of the pyroelectric field arising during cooling after laser heating.

Beamline electrostatic levitator for in situ high energy x-ray diffraction studies of levitated solids and liquids

Energy Technology Data Exchange (ETDEWEB)

Gangopadhyay, A.K.; Lee, G.W.; Kelto, K.F.; Rogers, J.R.; Goldman, A.I.; Robinson, D.S.; Rathz, T.J.; Hyers, R.W. (WU); (UAB); (NASA); (UMASS, Amherst)

2010-07-19

Determinations of the phase formation sequence, crystal structures and the thermo-physical properties of materials at high temperatures are hampered by contamination from the sample container and environment. Containerless processing techniques, such as electrostatic (ESL), electromagnetic, aerodynamic, and acoustic levitation, are most suitable for these studies. An adaptation of ESL for in situ structural studies of a wide range of materials using high energy (30-130 keV) x rays at a synchrotron source is described here. This beamline ESL (BESL) allows the in situ determination of the atomic structures of equilibrium solid and liquid phases, undercooled liquids and time-resolved studies of solid-solid and liquid-solid phase transformations. The use of area detectors enables the rapid acquisition of complete diffraction patterns over a wide range (0.5-14 {angstrom}{sup -1}) of reciprocal space. The wide temperature range (300-2500 K), containerless processing environment under high vacuum (10{sup -7}-10{sup -8} Torr), and fast data acquisition capability, make BESL particularly well suited for phase stability studies of high temperature solids and liquids. An additional, but important, feature of BESL is the capability for simultaneous measurements of a host of thermo-physical properties including the specific heat, enthalpy of transformation, solidus and liquidus temperatures, density, viscosity, and surface tension, all on the same sample during the structural measurements.

Application of Genomic In Situ Hybridization in Horticultural Science

Directory of Open Access Journals (Sweden)

Fahad Ramzan

2017-01-01

Full Text Available Molecular cytogenetic techniques, such as in situ hybridization methods, are admirable tools to analyze the genomic structure and function, chromosome constituents, recombination patterns, alien gene introgression, genome evolution, aneuploidy, and polyploidy and also genome constitution visualization and chromosome discrimination from different genomes in allopolyploids of various horticultural crops. Using GISH advancement as multicolor detection is a significant approach to analyze the small and numerous chromosomes in fruit species, for example, Diospyros hybrids. This analytical technique has proved to be the most exact and effective way for hybrid status confirmation and helps remarkably to distinguish donor parental genomes in hybrids such as Clivia, Rhododendron, and Lycoris ornamental hybrids. The genome characterization facilitates in hybrid selection having potential desirable characteristics during the early hybridization breeding, as this technique expedites to detect introgressed sequence chromosomes. This review study epitomizes applications and advancements of genomic in situ hybridization (GISH techniques in horticultural plants.

Recent Advances on In Situ SEM Mechanical and Electrical Characterization of Low-Dimensional Nanomaterials.

Science.gov (United States)

Jiang, Chenchen; Lu, Haojian; Zhang, Hongti; Shen, Yajing; Lu, Yang

2017-01-01

In the past decades, in situ scanning electron microscopy (SEM) has become a powerful technique for the experimental study of low-dimensional (1D/2D) nanomaterials, since it can provide unprecedented details for individual nanostructures upon mechanical and electrical stimulus and thus uncover the fundamental deformation and failure mechanisms for their device applications. In this overview, we summarized recent developments on in situ SEM-based mechanical and electrical characterization techniques including tensile, compression, bending, and electrical property probing on individual nanostructures, as well as the state-of-the-art electromechanical coupling analysis. In addition, the advantages and disadvantages of in situ SEM tests were also discussed with some possible solutions to address the challenges. Furthermore, critical challenges were also discussed for the development and design of robust in situ SEM characterization platform with higher resolution and wider range of samples. These experimental efforts have offered in-depth understanding on the mechanical and electrical properties of low-dimensional nanomaterial components and given guidelines for their further structural and functional applications.

Recent Advances on In Situ SEM Mechanical and Electrical Characterization of Low-Dimensional Nanomaterials

Directory of Open Access Journals (Sweden)

Chenchen Jiang

2017-01-01

Full Text Available In the past decades, in situ scanning electron microscopy (SEM has become a powerful technique for the experimental study of low-dimensional (1D/2D nanomaterials, since it can provide unprecedented details for individual nanostructures upon mechanical and electrical stimulus and thus uncover the fundamental deformation and failure mechanisms for their device applications. In this overview, we summarized recent developments on in situ SEM-based mechanical and electrical characterization techniques including tensile, compression, bending, and electrical property probing on individual nanostructures, as well as the state-of-the-art electromechanical coupling analysis. In addition, the advantages and disadvantages of in situ SEM tests were also discussed with some possible solutions to address the challenges. Furthermore, critical challenges were also discussed for the development and design of robust in situ SEM characterization platform with higher resolution and wider range of samples. These experimental efforts have offered in-depth understanding on the mechanical and electrical properties of low-dimensional nanomaterial components and given guidelines for their further structural and functional applications.

Photon structure function - theory

International Nuclear Information System (INIS)

Bardeen, W.A.

1984-12-01

The theoretical status of the photon structure function is reviewed. Particular attention is paid to the hadronic mixing problem and the ability of perturbative QCD to make definitive predictions for the photon structure function. 11 references

A flow-through hydrothermal cell for in situ neutron diffraction studies of phase transformations

International Nuclear Information System (INIS)

O'Neill, Brian; Tenailleau, Christophe; Nogthai, Yung; Studer, Andrew; Brugger, Joel; Pring, Allan

2006-01-01

A flow-through hydrothermal cell for the in situ neutron diffraction study of crystallisation and phase transitions has been developed. It can be used for kinetic studies on materials that exhibit structural transformations under hydrothermal conditions. It is specifically designed for use on the medium-resolution powder diffractometer (MRPD) at ANSTO, Lucas Heights, Sydney. But it is planned to adapt the design for the Polaris beamline at ISIS and the new high-intensity powder diffractometer (Wombat) at the new Australian reactor Opal. The cell will operate in a flow-through mode over the temperature range from 25-300 deg. C and up to pressures of 100 bar. The first results of a successful transformation of pentlandite (Fe,Ni) 9 S 8 to violarite (Fe,Ni) 3 S 4 under mild conditions (pH∼4) at 120 deg. C and 3 bar using in situ neutron diffraction measurements are presented

Nuclear correlations and structure functions

International Nuclear Information System (INIS)

Hu Guoju; Irvine, J.M.

1989-01-01

It is argued that the search for a mass number dependence of the nuclear structure function per nucleon is profitably directed to the region of Bjorken scaling variable x > 1. We show that in the convolution model of the nuclear structure function the nuclear momentum distribution and energy spectrum generated by cluster expansion techniques, here realised in the correlated basis function method, invoking tensor correlations and short-range density-dependent repulsions adequately describes the structure function for 12 C in the region x > 1. The results of structure functions for a number of light-, medium- and heavy-mass nuclei are presented. (author)

Mind, brain, structure and function

Energy Technology Data Exchange (ETDEWEB)

Aleksander, I

1982-01-01

The author discusses the type of problem one encounters when trying to formalise the nature of a state structure associated with the brain and the origins of this state structure. The paper first defines in broad terms the nature of the structure function problem, and then goes on to separate out those parts of a structure that lead to the variational and adaptive nature of the state structure. It is argued that the relationship between the structure that leads to adaptation and its embedding in an external environment are crucial areas for further study. 4 references.

Structure-based inference of molecular functions of proteins of unknown function from Berkeley Structural Genomics Center

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung-Hou; Shin, Dong Hae; Hou, Jingtong; Chandonia, John-Marc; Das, Debanu; Choi, In-Geol; Kim, Rosalind; Kim, Sung-Hou

2007-09-02

Advances in sequence genomics have resulted in an accumulation of a huge number of protein sequences derived from genome sequences. However, the functions of a large portion of them cannot be inferred based on the current methods of sequence homology detection to proteins of known functions. Three-dimensional structure can have an important impact in providing inference of molecular function (physical and chemical function) of a protein of unknown function. Structural genomics centers worldwide have been determining many 3-D structures of the proteins of unknown functions, and possible molecular functions of them have been inferred based on their structures. Combined with bioinformatics and enzymatic assay tools, the successful acceleration of the process of protein structure determination through high throughput pipelines enables the rapid functional annotation of a large fraction of hypothetical proteins. We present a brief summary of the process we used at the Berkeley Structural Genomics Center to infer molecular functions of proteins of unknown function.

Magnetic monolayers on semiconducting substrates. An in situ FMR study of Fe-based heterostructures

Energy Technology Data Exchange (ETDEWEB)

Zakeri Lori, K.

2007-10-18

The growth, magnetic anisotropy, g-factor, and magnetization of Fe monolayers grown on GaAs(001), InAs(001), and InP(001) are investigated by a combination of in situ ferromagnetic resonance and SQUID magnetometry as a function of temperature and film thickness. The effect of stress caused by the lattice mismatch and the surface reconstruction on the magnetic anisotropy is quantified. An in-plane spin reorientation transition as a function of film thickness is observed at room temperature for all systems. A magneto-elastic model is used to explain the direction of the easy axis, the spin reorientation transition, and the contributions to the magnetic anisotropy terms using the stress components measured directly by in situ IV-low-energy electron diffraction. While the model gives a quantitative explanation of the out-of-plane magnetic anisotropy, changes of the electronic interface structure have to be taken into account for the in-plane magnetic anisotropy. The influence of Ag and Au buffer and cap layers on the magnetic anisotropy terms are determined. The temperature dependence of the total magnetic anisotropy, as well as the surface-interface and volume contribution to the magnetic anisotropy are determined for Fe monolayers on GaAs(001). It is demonstrated that the temperature dependence of the magnetic anisotropy is correlated with the temperature dependence of the magnetization according to the Callen-Callen model. The temperature dependence of the volume contribution to the perpendicular magnetic anisotropy is fully explained by the temperature dependence of the magneto-elastic anisotropy. A temperature-driven morphological transformation occurring at a temperature higher than 550 K depending on the film thickness is observed. The thin Fe3Si binary Heusler structure epitaxially grown on MgO(001) is investigated. In addition to the structural properties, magnetic anisotropy, magnetization, g-factor, spin, and orbital magnetism, the magnetic relaxation

Structure, thermal and mechanical properties of in situ Al-based metal matrix composite reinforced with Al2O3 and TiC submicron particles

International Nuclear Information System (INIS)

Yu Peng; Mei Zhi; Tjong, S.C.

2005-01-01

We report herein the structure and characterization of in situ Al-based metal matrix composites (MMCs) prepared from the Al-10 wt.% TiO 2 and Al-10 wt.% TiO 2 -1.5 wt.% C systems via hot isostatic pressing (HIP) at 1000 deg C and 100 MPa. The structure, morphology and thermal behavior of HIPed samples were studied by means of the X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicated that fined Al 2 O 3 particles and large intermetallic Al 3 Ti plates were in situ formed in the Al-10 wt.% TiO 2 sample during HIPing. However, the introduction of C to the Al-TiO 2 system was beneficial to eliminate large intermetallic Al 3 Ti plates. In this case, Al 2 O 3 and TiC submicron particles were in situ formed in the Al-10 wt.% TiO 2 -1.5 wt.% C sample. Three-point-bending test showed that the strength and the strain-at-break of the HIPed Al-10 wt.% TiO 2 -1.5 wt.% C sample were significantly higher than those of its Al-10 wt.% TiO 2 counterpart. The improvement was derived from the elimination of bulk Al 3 Ti intermetallic plates and from the formation of TiC submicron particles. DSC measurements and thermodynamic analyses were carried out to reveal the reaction formation mechanisms of in situ reinforcing phases. The DSC results generally correlated well with the theoretical predictions. Finally, the correlation between the structure-property relationships of in situ composites is discussed

Structural optimization and structure-functional selectivity relationship studies of G protein-biased EP2 receptor agonists.

Science.gov (United States)

Ogawa, Seiji; Watanabe, Toshihide; Moriyuki, Kazumi; Goto, Yoshikazu; Yamane, Shinsaku; Watanabe, Akio; Tsuboi, Kazuma; Kinoshita, Atsushi; Okada, Takuya; Takeda, Hiroyuki; Tani, Kousuke; Maruyama, Toru

2016-05-15

The modification of the novel G protein-biased EP2 agonist 1 has been investigated to improve its G protein activity and develop a better understanding of its structure-functional selectivity relationship (SFSR). The optimization of the substituents on the phenyl ring of 1, followed by the inversion of the hydroxyl group on the cyclopentane moiety led to compound 9, which showed a 100-fold increase in its G protein activity compared with 1 without any increase in β-arrestin recruitment. Furthermore, SFSR studies revealed that the combination of meta and para substituents on the phenyl moiety was crucial to the functional selectivity. Copyright © 2016 Elsevier Ltd. All rights reserved.

In situ deposition of hydroxyapatite on graphene nanosheets

International Nuclear Information System (INIS)

Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

2013-01-01

Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH 4 etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HA was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.

In situ deposition of hydroxyapatite on graphene nanosheets

Energy Technology Data Exchange (ETDEWEB)

Neelgund, Gururaj M. [Department of Chemistry, Prairie View A and M University, Prairie View, TX 77446 (United States); Oki, Aderemi, E-mail: aroki@pvamu.edu [Department of Chemistry, Prairie View A and M University, Prairie View, TX 77446 (United States); Luo, Zhiping [Microscopy and Imaging Center and Materials Science and Engineering Program, Texas A and M University, College Station, TX 77843 (United States)

2013-02-15

Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH{sub 4} etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HA was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.

In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications.

Science.gov (United States)

Wan, Mimi; Zhang, Jin; Wang, Qi; Zhan, Shuyue; Chen, Xudong; Mao, Chun; Liu, Yuhong; Shen, Jian

2017-06-07

Mesoporous silica has been developed for the modification of titanium surfaces that are used as implant materials. Yet, the traditional modification methods failed to effectively construct mesoporous silica on the titanium surface evenly and firmly, in which the interaction between mesoporous silica and titanium was mainly physical. Here, in situ growth of mesoporous silica on a titanium surface was performed using a simple evaporation-induced self-assembly strategy. Meantime, in situ introduction of drugs (heparin and vancomycin) to mesoporous silica was also adopted to improve the drug-loading amount. Both the above-mentioned processes were completed at the same time. Transmission electron microscopy, N 2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle measurements were used to characterize the structure of the mesoporous silica film. Results indicated that the mesoporous silica film that in situ grew on the titanium surface was smooth, thin, transparent, and stable. Cytotoxicity, proliferation performance of osteoblast cells, and in vitro and in vivo studies of the antibacterial activity of the coating were tested. This is the first study to modify the titanium surface by the in situ growth of a mesoporous silica coating with two kinds of drugs. The stability of the mesoporous silica coating can be attributed to the chemical bonding between dopamine and silicon hydroxyl of the mesoporous silica coating, and the smooth surface of mesoporous silica is a result of the method of in situ growth. The large amount of drug-loading also could be ascribed to the in situ introduction of drugs during the synthetic process. The strategy proposed in this work will bring more possibilities for the preparation of advanced functional materials based on the combination of mesoporous structure and metallic materials.

Study of the Wigner function at the device boundaries in one-dimensional single- and double-barrier structures

International Nuclear Information System (INIS)

Savio, Andrea; Poncet, Alain

2011-01-01

In this work, we compute the Wigner distribution function on one-dimensional devices from wave functions generated by solving the Schroedinger equation. Our goal is to investigate certain issues that we encountered in implementing Wigner transport equation solvers, such as the large discrepancies observed between the boundary conditions and the solution in the neighborhood of the boundaries. By evaluating the Wigner function without solving the Wigner transport equation, we intend to ensure that the actual boundary conditions are consistent with those commonly applied in literature. We study both single- and double-barrier unbiased structures. We use simple potential profiles, so that we can compute the wave functions analytically for better accuracy. We vary a number of structure geometry, material, meshing, and numerical parameters, among which are the contact length, the barrier height, the number of incident wave functions, and the numerical precision used for the computations, and we observe how the Wigner function at the device boundaries is affected. For the double-barrier structures, we look at the density matrix function and we study a model for the device transmission spectrum which helps explain the lobelike artifacts that we observe on the Wigner function.

Functional materials discovery using energy-structure-function maps.

Science.gov (United States)

Pulido, Angeles; Chen, Linjiang; Kaczorowski, Tomasz; Holden, Daniel; Little, Marc A; Chong, Samantha Y; Slater, Benjamin J; McMahon, David P; Bonillo, Baltasar; Stackhouse, Chloe J; Stephenson, Andrew; Kane, Christopher M; Clowes, Rob; Hasell, Tom; Cooper, Andrew I; Day, Graeme M

2017-03-30

Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal-organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy-structure-function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy-structure-function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

Deep pelagic food web structure as revealed by in situ feeding observations.

Science.gov (United States)

Choy, C Anela; Haddock, Steven H D; Robison, Bruce H

2017-12-06

Food web linkages, or the feeding relationships between species inhabiting a shared ecosystem, are an ecological lens through which ecosystem structure and function can be assessed, and thus are fundamental to informing sustainable resource management. Empirical feeding datasets have traditionally been painstakingly generated from stomach content analysis, direct observations and from biochemical trophic markers (stable isotopes, fatty acids, molecular tools). Each approach carries inherent biases and limitations, as well as advantages. Here, using 27 years (1991-2016) of in situ feeding observations collected by remotely operated vehicles (ROVs), we quantitatively characterize the deep pelagic food web of central California within the California Current, complementing existing studies of diet and trophic interactions with a unique perspective. Seven hundred and forty-three independent feeding events were observed with ROVs from near-surface waters down to depths approaching 4000 m, involving an assemblage of 84 different predators and 82 different prey types, for a total of 242 unique feeding relationships. The greatest diversity of prey was consumed by narcomedusae, followed by physonect siphonophores, ctenophores and cephalopods. We highlight key interactions within the poorly understood 'jelly web', showing the importance of medusae, ctenophores and siphonophores as key predators, whose ecological significance is comparable to large fish and squid species within the central California deep pelagic food web. Gelatinous predators are often thought to comprise relatively inefficient trophic pathways within marine communities, but we build upon previous findings to document their substantial and integral roles in deep pelagic food webs. © 2017 The Authors.

Structure functions and correlations in nuclei

International Nuclear Information System (INIS)

Schiavilla, R.; Lewart, D.S.; Pandharipande, V.R.

1987-01-01

The static longitudinal structure function S l (k) and the static structure function S(k) of 3 H, 3 He and 4 He nuclei and nuclear matter are calculated using realistic wave functions obtained from Faddeev and variational calculations. In order to study the variation of the structure function with the number of particles in the system we also calculate S(k) of atomic helium liquid drops containing 4, 8, 20, 40, 70, 168 and 240 atoms. Monte Carlo integration is used to calculate the structure functions of finite systems, while those of nuclear matter are calculated with chain summation methods. The behaivior of S(k) and S l (k) at small values of k is discussed. We find that the recent Saclay data on S l (k) of the 3 He nucleus are in agreement with theory. Though the data indicate the the existence of correlations between the two protons in the 3 He nucleus, they are not accurate enough to draw interesting conclusions about the repulsive core in the nucleon-nucleon interaction. The structure functions of atomic helium liquid drops indicate a smooth variation of S(k) with the number of atoms in the drop. The S L (k) of the 4 He nucleus and nuclear matter are very similar for k > 1.5 fm -1 , and it appears plausible that S L (k) of nuclei having A > 3 may not depend significantly on A when k > 1.5 fm -1 . (orig.)

Atomic-resolution environmental TEM for quantitative in-situ microscopy in materials science.

Science.gov (United States)

Takeda, Seiji; Yoshida, Hideto

2013-02-01

We have compiled our recent in-situ quantitative environmental transmission electron microscopy (ETEM) studies on typical gold nanoparticulate catalysts for the low-temperature oxidation of CO to describe the issues surrounding the application of ETEM, with a special regard to catalyst chemistry. Thanks to the recent development of high-resolution environmental transmission electron microscopes that can work robustly to accumulate observation data in controlled environments, we can deal with the electron irradiation effects and heterogeneity of real catalysts. We established a structural evolution diagram that summarizes the structure of catalysts under electron irradiation as a function of the electron current density ϕ and the electron dose, D. By extrapolating to ϕ = 0, D = 0, we could deduce the intrinsic catalysis structure (without electron irradiation) in various environments, including reaction environments. By numerically and statistically analyzing a substantial number of ETEM images of gold nanoparticles, we established a morphology phase diagram that summarizes how the majority of gold nanoparticles change their morphology systematically as a function of the partial pressures of CO and O(2). Similar diagrams will be helpful in elucidating the phenomena that directly correlate with the catalytic activity determined from ETEM observations. Using these quantitative analyses, we could analyze Cs-corrected ETEM images of the catalysts. The surfaces of gold nanoparticles were structurally reconstructed under reaction conditions, via interactions with CO molecules. CO molecules were observed on the surfaces of catalysts under reaction conditions using high-resolution ETEM. Finally, we discuss the potential of environmental transmission electron microscopy for quantitative in-situ microscopy at the atomic scale.

The study of structural characteristic of yttrium(3+) aquaion by density functional methods

International Nuclear Information System (INIS)

Buz'ko, V.Yu.; Sukhno, I.V.; Polushin, A.A.; Panyushkin, V.T.

2006-01-01

Structural characteristics of the yttrium aquaion Y(H 2 O) 8 3+ are calculated by DFT technique using density functionals SVWN5, B3LYP, B3P86, O3LYP, B3PW91, B1LYP, B971, MPW1PW9, PBE1PBE, BHandH and BNandHLYP. All calculations are carried out by means of GAUSSIAN-03 code. Structural characteristics of the Y(H 2 O) 8 3+ aquaion obtained by the use of the density functional method agree satisfactorily with the experiment. Hybrid nonlocal GGA-functionals foretell worse the structural characteristics of the Y(H 2 O) 8 3+ aquaion as compared with the reasonable simple combined functional BHandH and the simplest functional SVWN5 of the LSDA theory [ru

A Structure-Function Study of RecA: The Structural Basis for ATP Specificity in the Strand Exchange Reaction

Science.gov (United States)

Gegner, Julie; Spruill, Natalie; Plesniak, Leigh A.

1999-11-01

The terms "structure" and "function" can assume a variety of meanings. In biochemistry, the "structure" of a protein can refer to its sequence of amino acids, the three-dimensional arrangement of atoms within a subunit, or the arrangement of subunits into a larger oligomeric or filamentous state. Likewise, the function of biological macromolecules can be examined at many levels. The function of a protein can be described by its role in an organism's survival or by a chemical reaction that it promotes. We have designed a three-part biochemical laboratory experiment that characterizes the structure and function of the Escherichia coli RecA protein. The first part examines the importance of RecA in the survival of bacteria that have been exposed to UV light. This is the broadest view of function of the enzyme. Second, the students use an in vitro assay of RecA whereby the protein promotes homologous recombination. Because RecA functions not catalytically, but rather stoichiometrically, in this recombination reaction, the oligomeric state of RecA in complex with DNA must also be discussed. Finally, through molecular modeling of X-ray crystallographic structures, students identify functionally important features of the ATP cofactor binding site of RecA.

A new in situ model to study erosive enamel wear, a clinical pilot study.

NARCIS (Netherlands)

Ruben, J.L.; Truin, G.J.; Bronkhorst, E.M.; Huysmans, M.C.D.N.J.M.

2017-01-01

OBJECTIVES: To develop an in situ model for erosive wear research which allows for more clinically relevant exposure parameters than other in situ models and to show tooth site-specific erosive wear effect of an acid challenge of orange juice on enamel. METHODS: This pilot study included 6

Structure function monitor

Science.gov (United States)

McGraw, John T [Placitas, NM; Zimmer, Peter C [Albuquerque, NM; Ackermann, Mark R [Albuquerque, NM

2012-01-24

Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.

In situ x-ray diffraction studies of three-dimensional C60 polymers

International Nuclear Information System (INIS)

Wood, R A; Lewis, M H; Bennington, S M; Cain, M G; Kitamura, N; Fukumi, A K

2002-01-01

In situ investigations into the P/T field of C 60 fullerene were performed using energy-dispersive x-ray diffraction techniques. Isobars were obtained at 11 and 9 GPa accompanied by isotherms at 750 and 800 K with pressure reaching 13 GPa. The P/T history and pressure isotropy were investigated with the aim of optimizing conditions for 3D polymer formation. Confirmation of the formation of 3D polymers was performed in situ; however, the reclaimed sample did not exhibit the expected high hardness value, due to depolymerization on pressure release. Isotropy in the pressure field promoted formation and retention of the face-centred-cubic structure

The structure and function of the pericellular matrix of articular cartilage.

Science.gov (United States)

Wilusz, Rebecca E; Sanchez-Adams, Johannah; Guilak, Farshid

2014-10-01

Chondrocytes in articular cartilage are surrounded by a narrow pericellular matrix (PCM) that is both biochemically and biomechanically distinct from the extracellular matrix (ECM) of the tissue. While the PCM was first observed nearly a century ago, its role is still under investigation. In support of early hypotheses regarding its function, increasing evidence indicates that the PCM serves as a transducer of biochemical and biomechanical signals to the chondrocyte. Work over the past two decades has established that the PCM in adult tissue is defined biochemically by several molecular components, including type VI collagen and perlecan. On the other hand, the biomechanical properties of this structure have only recently been measured. Techniques such as micropipette aspiration, in situ imaging, computational modeling, and atomic force microscopy have determined that the PCM exhibits distinct mechanical properties as compared to the ECM, and that these properties are influenced by specific PCM components as well as disease state. Importantly, the unique relationships among the mechanical properties of the chondrocyte, PCM, and ECM in different zones of cartilage suggest that this region significantly influences the stress-strain environment of the chondrocyte. In this review, we discuss recent advances in the measurement of PCM mechanical properties and structure that further increase our understanding of PCM function. Taken together, these studies suggest that the PCM plays a critical role in controlling the mechanical environment and mechanobiology of cells in cartilage and other cartilaginous tissues, such as the meniscus or intervertebral disc. Copyright © 2014 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.

In situ structural analysis of calcium aluminosilicate glasses under high pressure.

Science.gov (United States)

Muniz, R F; de Ligny, D; Martinet, C; Sandrini, M; Medina, A N; Rohling, J H; Baesso, M L; Lima, S M; Andrade, L H C; Guyot, Y

2016-08-10

In situ micro-Raman spectroscopy was used to investigate the structural evolution of OH(-)-free calcium aluminosilicate glasses, under high pressure and at room temperature. Evaluation was made of the role of the SiO2 concentration in percalcic join systems, for Al/(Al  +  Si) in the approximate range from 0.9 to 0.2. Under high pressure, the intensity of the main band related to the bending mode of bridging oxygen ([Formula: see text][T-O-T], where T  =  Si or Al) decreased gradually, suggesting that the bonds were severely altered or even destroyed. In Si-rich glasses, compression induced a transformation of Q (n) species to Q (n-1). In the case of Al-rich glass, the Al in the smallest Q (n) units evolved from tetrahedral to higher-coordinated Al (([5])Al and ([6])Al). Permanent structural changes were observed in samples recovered from the highest pressure of around 15 GPa and, particularly for Si-rich samples, the recovered structure showed an increase of three-membered rings in the Si/Al tetrahedral network.

Structure-function relationships during segregated and integrated network states of human brain functional connectivity.

Science.gov (United States)

Fukushima, Makoto; Betzel, Richard F; He, Ye; van den Heuvel, Martijn P; Zuo, Xi-Nian; Sporns, Olaf

2018-04-01

Structural white matter connections are thought to facilitate integration of neural information across functionally segregated systems. Recent studies have demonstrated that changes in the balance between segregation and integration in brain networks can be tracked by time-resolved functional connectivity derived from resting-state functional magnetic resonance imaging (rs-fMRI) data and that fluctuations between segregated and integrated network states are related to human behavior. However, how these network states relate to structural connectivity is largely unknown. To obtain a better understanding of structural substrates for these network states, we investigated how the relationship between structural connectivity, derived from diffusion tractography, and functional connectivity, as measured by rs-fMRI, changes with fluctuations between segregated and integrated states in the human brain. We found that the similarity of edge weights between structural and functional connectivity was greater in the integrated state, especially at edges connecting the default mode and the dorsal attention networks. We also demonstrated that the similarity of network partitions, evaluated between structural and functional connectivity, increased and the density of direct structural connections within modules in functional networks was elevated during the integrated state. These results suggest that, when functional connectivity exhibited an integrated network topology, structural connectivity and functional connectivity were more closely linked to each other and direct structural connections mediated a larger proportion of neural communication within functional modules. Our findings point out the possibility of significant contributions of structural connections to integrative neural processes underlying human behavior.

The notochord: structure and functions.

Science.gov (United States)

Corallo, Diana; Trapani, Valeria; Bonaldo, Paolo

2015-08-01

The notochord is an embryonic midline structure common to all members of the phylum Chordata, providing both mechanical and signaling cues to the developing embryo. In vertebrates, the notochord arises from the dorsal organizer and it is critical for proper vertebrate development. This evolutionary conserved structure located at the developing midline defines the primitive axis of embryos and represents the structural element essential for locomotion. Besides its primary structural function, the notochord is also a source of developmental signals that patterns surrounding tissues. Among the signals secreted by the notochord, Hedgehog proteins play key roles during embryogenesis. The Hedgehog signaling pathway is a central regulator of embryonic development, controlling the patterning and proliferation of a wide variety of organs. In this review, we summarize the current knowledge on notochord structure and functions, with a particular emphasis on the key developmental events that take place in vertebrates. Moreover, we discuss some genetic studies highlighting the phenotypic consequences of impaired notochord development, which enabled to understand the molecular basis of different human congenital defects and diseases.

In-situ burning: NIST studies

International Nuclear Information System (INIS)

Evans, D.D.

1992-01-01

In-situ burning of spilled oil has distinct advantages over other countermeasures. It offers the potential to convert rapidly large quantities of oil into its primary combustion products, carbon dioxide and water, with a small percentage of other unburned and residue byproducts. Because the oil is converted to gaseous products of combustion by burning, the need for physical collection, storage, and transport of recovered fluids is reduced to the few percent of the original spill volume that remains as residue after burning. Burning oil spills produces a visible smoke plume containing smoke particulate and other products of combustion which may persist for many kilometers from the burn. This fact gives rise to public health concerns, related to the chemical content of the smoke plume and the downwind deposition of particulate, which need to be answered. In 1985, a joint Minerals Management Service (MMS) and Environment Canada (EC) in-situ burning research program was begun at the National Institute of Standards and Technology (NIST). This research program was designed to study the burning of large crude oil spills on water and how this burning would affect air quality by quantifying the products of combustion and developing methods to predict the downwind smoke particulate deposition. To understand the important features of in-situ burning, it is necessary to perform both laboratory and mesoscale experiments. Finally, actual burns of spilled oil at sea will be necessary to evaluate the method at the anticipated scale of actual response operations. In this research program there is a continuing interaction between findings from measurements on small fire experiments performed in the controlled laboratory environments of NIST and the Fire Research Institute (FRI) in Japan, and large fire experiments at facilities like the USCG Fire Safety and Test Detachment in Mobile, Alabama where outdoor liquid fuel burns in large pans are possible

Massively Parallel Interrogation of Aptamer Sequence, Structure and Function

Energy Technology Data Exchange (ETDEWEB)

Fischer, N O; Tok, J B; Tarasow, T M

2008-02-08

Optimization of high affinity reagents is a significant bottleneck in medicine and the life sciences. The ability to synthetically create thousands of permutations of a lead high-affinity reagent and survey the properties of individual permutations in parallel could potentially relieve this bottleneck. Aptamers are single stranded oligonucleotides affinity reagents isolated by in vitro selection processes and as a class have been shown to bind a wide variety of target molecules. Methodology/Principal Findings. High density DNA microarray technology was used to synthesize, in situ, arrays of approximately 3,900 aptamer sequence permutations in triplicate. These sequences were interrogated on-chip for their ability to bind the fluorescently-labeled cognate target, immunoglobulin E, resulting in the parallel execution of thousands of experiments. Fluorescence intensity at each array feature was well resolved and shown to be a function of the sequence present. The data demonstrated high intra- and interchip correlation between the same features as well as among the sequence triplicates within a single array. Consistent with aptamer mediated IgE binding, fluorescence intensity correlated strongly with specific aptamer sequences and the concentration of IgE applied to the array. The massively parallel sequence-function analyses provided by this approach confirmed the importance of a consensus sequence found in all 21 of the original IgE aptamer sequences and support a common stem:loop structure as being the secondary structure underlying IgE binding. The microarray application, data and results presented illustrate an efficient, high information content approach to optimizing aptamer function. It also provides a foundation from which to better understand and manipulate this important class of high affinity biomolecules.

Massively parallel interrogation of aptamer sequence, structure and function.

Directory of Open Access Journals (Sweden)

Nicholas O Fischer

Full Text Available BACKGROUND: Optimization of high affinity reagents is a significant bottleneck in medicine and the life sciences. The ability to synthetically create thousands of permutations of a lead high-affinity reagent and survey the properties of individual permutations in parallel could potentially relieve this bottleneck. Aptamers are single stranded oligonucleotides affinity reagents isolated by in vitro selection processes and as a class have been shown to bind a wide variety of target molecules. METHODOLOGY/PRINCIPAL FINDINGS: High density DNA microarray technology was used to synthesize, in situ, arrays of approximately 3,900 aptamer sequence permutations in triplicate. These sequences were interrogated on-chip for their ability to bind the fluorescently-labeled cognate target, immunoglobulin E, resulting in the parallel execution of thousands of experiments. Fluorescence intensity at each array feature was well resolved and shown to be a function of the sequence present. The data demonstrated high intra- and inter-chip correlation between the same features as well as among the sequence triplicates within a single array. Consistent with aptamer mediated IgE binding, fluorescence intensity correlated strongly with specific aptamer sequences and the concentration of IgE applied to the array. CONCLUSION AND SIGNIFICANCE: The massively parallel sequence-function analyses provided by this approach confirmed the importance of a consensus sequence found in all 21 of the original IgE aptamer sequences and support a common stem:loop structure as being the secondary structure underlying IgE binding. The microarray application, data and results presented illustrate an efficient, high information content approach to optimizing aptamer function. It also provides a foundation from which to better understand and manipulate this important class of high affinity biomolecules.

Molecular Details of Olfactomedin Domains Provide Pathway to Structure-Function Studies.

Directory of Open Access Journals (Sweden)

Shannon E Hill

Full Text Available Olfactomedin (OLF domains are found within extracellular, multidomain proteins in numerous tissues of multicellular organisms. Even though these proteins have been implicated in human disorders ranging from cancers to attention deficit disorder to glaucoma, little is known about their structure(s and function(s. Here we biophysically, biochemically, and structurally characterize OLF domains from H. sapiens olfactomedin-1 (npoh-OLF, also called noelin, pancortin, OLFM1, and hOlfA, and M. musculus gliomedin (glio-OLF, also called collomin, collmin, and CRG-L2, and compare them with available structures of myocilin (myoc-OLF recently reported by us and R. norvegicus glio-OLF and M. musculus latrophilin-3 (lat3-OLF by others. Although the five-bladed β-propeller architecture remains unchanged, numerous physicochemical characteristics differ among these OLF domains. First, npoh-OLF and glio-OLF exhibit prominent, yet distinct, positive surface charges and copurify with polynucleotides. Second, whereas npoh-OLF and myoc-OLF exhibit thermal stabilities typical of human proteins near 55°C, and most myoc-OLF variants are destabilized and highly prone to aggregation, glio-OLF is nearly 20°C more stable and significantly more resistant to chemical denaturation. Phylogenetically, glio-OLF is most similar to primitive OLFs, and structurally, glio-OLF is missing distinguishing features seen in OLFs such as the disulfide bond formed by N- and C- terminal cysteines, the sequestered Ca2+ ion within the propeller central hydrophilic cavity, and a key loop-stabilizing cation-π interaction on the top face of npoh-OLF and myoc-OLF. While deciphering the explicit biological functions, ligands, and binding partners for OLF domains will likely continue to be a challenging long-term experimental pursuit, we used structural insights gained here to generate a new antibody selective for myoc-OLF over npoh-OLF and glio-OLF as a first step in overcoming the impasse in

Magneto-structural correlations in trinuclear Cu(II) complexes: a density functional study

CERN Document Server

Rodríguez-Forteá, A; Alvarez, S; Centre-De Recera-En-Quimica-Teorica; Alemany, P A; Centre-De Recera-En-Quimica-Teorica

2003-01-01

Density functional theoretical methods have been used to study magneto-structural correlations for linear trinuclear hydroxo-bridged copper(II) complexes. The nearest-neighbor exchange coupling constant shows very similar trends to those found earlier for dinuclear compounds for which the Cu-O-Cu angle and the out of plane displacement of the hydrogen atoms at the bridge are the two key structural factors that determine the nature of their magnetic behavior. Changes in these two parameters can induce variations of over 1000 cm sup - sup 1 in the value of the nearest-neighbor coupling constant. On the contrary, coupling between next-nearest neighbors is found to be practically independent of structural changes with a value for the coupling constant of about -60 cm sup - sup 1. The magnitude calculated for this coupling constant indicates that considering its value to be negligible, as usually done in experimental studies, can lead to considerable errors, especially for compounds in which the nearest-neighbor c...

In-situ investigations of structural changes during cyclic loading by high resolution reciprocal space mapping

DEFF Research Database (Denmark)

Diederichs, Annika M.; Thiel, Felix; Lienert, Ulrich

2017-01-01

dislocation structures can be identified using advanced electron microscopy and synchrotron techniques. A detailed characterization of the microstructure during cyclic loading by in-situ monitoring the internal structure within individual grains with high energy x-rays can help to understand and predict...... the materials behavior during cyclic deformation and to improve the material design. While monitoring macroscopic stress and strain during cyclic loading, reciprocal space maps of diffraction peaks from single grains are obtained with high resolution. High Resolution Reciprocal Space Mapping was applied...

Functional outcomes following syndesmotic fixation: A comparison of screws retained in situ versus routine removal - Is it really necessary?

Science.gov (United States)

Tucker, Adam; Street, Julia; Kealey, David; McDonald, Sinead; Stevenson, Mike

2013-12-01

Syndesmotic disruption can occur in up to 20% of ankle fractures and is more common in Weber Type C injuries. Syndesmotic repair aims to restore ankle stability. Routine removal of syndesmosis screws is advocated to avoid implant breakage and adverse functional outcome such as pain and stiffness, but conflicting evidence exists to support this. The aim of the current study is to determine whether functional outcome differs in patients who had syndesmosis screws routinely removed, compared to those who did not, and whether a cost benefit exists if removal of screws is not routinely necessary. A retrospective review of consecutive syndesmosis repairs was performed from 1 January 2008 to 31 December 2010 in a single regional trauma centre. We identified 91 patients who had undergone open reduction internal fixation of an ankle fracture with placement of a syndesmosis screw at index procedure. As many as 69 patients were eligible for the study as defined by the inclusion criteria and they completed a validated functional outcome questionnaire. The functional outcomes of patients with 'retained screws' and 'removed screws' were analysed and compared using the Olerud Molander Ankle Score (OMAS). A total of 63 patients responded with a mean follow-up period of 31 months (range 10-43 months). Of those patients, 43 underwent routine screw removal whilst 20 had screws left in situ. The groups were comparable considering age, gender and follow-up time. The 'retained' group scored higher mean OMAS scores, 81.5±19.3 compared to 75±12.9 in the 'removed' group (p=0.107). The retained group achieved higher functional scores in each of the OMAS domains as well as experiencing less pain. When adjusted for gender, the findings were found to be statistically significant (p=0.046). Our study has shown that retained-screw fixation does not significantly impair functional capacity, with additional cost-effectiveness. We therefore advocate that syndesmosis screws be left in situ and

Determination of the initial oxidation behavior of Zircaloy-4 by in-situ TEM

International Nuclear Information System (INIS)

Harlow, Wayne; Ghassemi, Hessam; Taheri, Mitra L.

2016-01-01

The corrosion behavior of Zircaloy-4 (Zry-4), specifically by oxidation, is a problem of great importance as this material is critical for current nuclear reactor cladding. The early formation behavior and structure of the oxide layer during oxidation was studied using in-situ TEM techniques that allowed for Zry-4 to be monitored during corrosion. These environmental exposure experiments were coupled with precession electron diffraction to identify and quantify the phases present in the samples before and after the oxidation. Following short-term, high temperature oxidation, the dominant phase was revealed to be monoclinic ZrO 2 in a columnar structure. These samples oxidized in-situ contained structures that correlated well with bulk Zry-4 subjected to autoclave treatment, which were used for comparison and validation of this technique. By using in-situ TEM the effect of microstructure features, such as grain boundaries, on oxidation behavior of an alloy can be studied. The technique presented herein holds the potential to be applied any alloy system to study these effects. - Highlights: • In-situ TEM was used to oxidize samples of Zircaloy-4. • Similar behavior was found in the in-situ oxidized and autoclave-oxidized samples. • Precession diffraction was used to characterize oxide phase and texture.

Atoms in Action: Observing Atomic Motion with Dynamic in situ X-ray Diffraction

Science.gov (United States)

Cox, Jordan Michael

environment is left static or data is not collected until after the material has equilibrated to its new environment. First, a unique ECC has been designed and constructed which allows continuous access to the local chemical environment of a single-crystal sample while maintaining ease of use, minimizing size, and which is easily adaptable to a wide variety of gaseous and liquid chemical stimuli. Novel methods have been developed and are herein described for utilizing this ECC and in situ X-ray diffraction methods in a dynamic manner for monitoring the structural responses of single crystals to changes in their local chemical environment. These methods provide the opportunity for the determination of changes in unit cell parameters and even complete crystal structures during adsorption, desorption, and exchange processes in MOF materials. The application of these methods to the determination of the dehydration process of a previously reported cobalt-based MOF have revealed surprising structural and dynamics data. Several new intermediate structures have been determined in this process, including one metastable species and several actively transitioning species during the dehydration process. Applying these methods to the ethanol solvation process in the same material again yielded results which were richer in structural information than the previously reported ex situ structures. A computational study of rotational potential energy surfaces in a family of photochromic MOF linkers revealed the important role rotational stereoisomers can play in maintaining light-activated functionality when these linkers are incorporated into next-generation functional MOF materials. Finally, the application of novel photocrystallography techniques were used in conjunction with spectroscopic methods to determine the nature of the anomalous behavior of a photochromic diarylethene single-crystal.

Optimized cryo-focused ion beam sample preparation aimed at in situ structural studies of membrane proteins.

Science.gov (United States)

Schaffer, Miroslava; Mahamid, Julia; Engel, Benjamin D; Laugks, Tim; Baumeister, Wolfgang; Plitzko, Jürgen M

2017-02-01

While cryo-electron tomography (cryo-ET) can reveal biological structures in their native state within the cellular environment, it requires the production of high-quality frozen-hydrated sections that are thinner than 300nm. Sample requirements are even more stringent for the visualization of membrane-bound protein complexes within dense cellular regions. Focused ion beam (FIB) sample preparation for transmission electron microscopy (TEM) is a well-established technique in material science, but there are only few examples of biological samples exhibiting sufficient quality for high-resolution in situ investigation by cryo-ET. In this work, we present a comprehensive description of a cryo-sample preparation workflow incorporating additional conductive-coating procedures. These coating steps eliminate the adverse effects of sample charging on imaging with the Volta phase plate, allowing data acquisition with improved contrast. We discuss optimized FIB milling strategies adapted from material science and each critical step required to produce homogeneously thin, non-charging FIB lamellas that make large areas of unperturbed HeLa and Chlamydomonas cells accessible for cryo-ET at molecular resolution. Copyright © 2016 Elsevier Inc. All rights reserved.

Fabrication of Nanocarbon Composites Using In Situ Chemical Vapor Deposition and Their Applications.

Science.gov (United States)

He, Chunnian; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun

2015-09-23

Nanocarbon (carbon nanotubes (CNTs) and graphene (GN)) composites attract considerable research interest due to their fascinating applications in many fields. Here, recent developments in the field of in situ chemical vapor deposition (CVD) for the design and controlled preparation of advanced nanocarbon composites are highlighted, specifically, CNT-reinforced bulk structural composites, as well as CNT, GN, and CNT/GN functional composites, together with their practical and potential applications. In situ CVD is a very attractive approach for the fabrication of composites because of its engaging features, such as its simplicity, low-cost, versatility, and tunability. The morphologies, structures, dispersion, and interface of the resulting nanocarbon composites can be easily modulated by varying the experimental parameters (such as temperature, catalysts, carbon sources, templates or template catalysts, etc.), which enables a great potential for the in situ synthesis of high-quality nanocarbons with tailored size and dimension for constructing high-performance composites, which has not yet been achieved by conventional methods. In addition, new trends of the in situ CVD toward nanocarbon composites are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Correlation of Theory and Function in Well-Defined Bimetallic Electrocatalysts - Final Report

Energy Technology Data Exchange (ETDEWEB)

Crooks, Richard M.

2014-06-05

The objective of this research proposal was to correlate the structure of nanoparticles that are comprised of ~100-200 atoms to their electrocatalytic function. This objective was based on the growing body of evidence suggesting that catalytic properties can be tailored through controlled synthesis of nanoparticles. What has been missing from many of these studies, and what we are contributing, is a model catalyst that is sufficiently small, structurally well-defined, and well-characterized that its function can be directly predicted by theory. Specifically, our work seeks to develop a fundamental and detailed understanding of the relationship between the structure of nanoscopic oxygen-reduction catalysts and their function. We assembled a team with expertise in theory, synthesis, and advanced characterization methods to address the primary objective of this project. We anticipated the outcomes of the study to be: (1) a better theoretical understanding of how nanoparticle structure affects catalytic properties; (2) the development of advanced, in-situ and ex-situ, atomic-scale characterization methods that are appropriate for particles containing about 100 atoms; and (3) improved synthetic methods that produce unique nanoparticle structures that can be used to test theoretical predictions. During the project period, we have made excellent progress on all three fronts.

Organizational Perspectives on Rapid Response Team Structure, Function, and Cost: A Qualitative Study.

Science.gov (United States)

Smith, Patricia L; McSweeney, Jean

Understanding how an organization determines structure and function of a rapid response team (RRT), as well as cost evaluation and implications, can provide foundational knowledge to guide decisions about RRTs. The objectives were to (1) identify influencing factors in organizational development of RRT structure and function and (2) describe evaluation of RRT costs. Using a qualitative, ethnographic design, nurse executives and experts in 15 moderate-size hospitals were interviewed to explore their decision-making processes in determining RRT structure and function. Face-to-face interviews were audio recorded and transcribed verbatim and verified for accurateness. Using content analysis and constant comparison, interview data were analyzed. Demographic data were analyzed using descriptive statistics. The sample included 27 participants from 15 hospitals in 5 south-central states. They described a variety of RRT responders and functions, with the majority of hospitals having a critical care charge nurse attending all RRT calls for assistance. Others described a designated RRT nurse with primary RRT duties as responder to all RRT calls. Themes of RRT development from the data included influencers, decision processes, and thoughts about cost. It is important to understand how hospitals determine optimal structure and function to enhance support of quality nursing care. Determining the impact of an RRT on costs and benefits is vital in balancing patient safety and limited resources. Future research should focus on clarifying differences between team structure and function in outcomes as well as the most effective means to estimate costs and benefits.

Functional Insights from Structural Genomics

Energy Technology Data Exchange (ETDEWEB)

Forouhar,F.; Kuzin, A.; Seetharaman, J.; Lee, I.; Zhou, W.; Abashidze, M.; Chen, Y.; Montelione, G.; Tong, L.; et al

2007-01-01

Structural genomics efforts have produced structural information, either directly or by modeling, for thousands of proteins over the past few years. While many of these proteins have known functions, a large percentage of them have not been characterized at the functional level. The structural information has provided valuable functional insights on some of these proteins, through careful structural analyses, serendipity, and structure-guided functional screening. Some of the success stories based on structures solved at the Northeast Structural Genomics Consortium (NESG) are reported here. These include a novel methyl salicylate esterase with important role in plant innate immunity, a novel RNA methyltransferase (H. influenzae yggJ (HI0303)), a novel spermidine/spermine N-acetyltransferase (B. subtilis PaiA), a novel methyltransferase or AdoMet binding protein (A. fulgidus AF{_}0241), an ATP:cob(I)alamin adenosyltransferase (B. subtilis YvqK), a novel carboxysome pore (E. coli EutN), a proline racemase homolog with a disrupted active site (B. melitensis BME11586), an FMN-dependent enzyme (S. pneumoniae SP{_}1951), and a 12-stranded {beta}-barrel with a novel fold (V. parahaemolyticus VPA1032).

Model for the analysis of sun radiation structures exposed to open air: consideration of its validity and usefulness based on its experimentation in situ

Science.gov (United States)

Bottoni, Mario; Fabretti, Giuseppe

2001-03-01

The definition of the thermal dynamics of a structure-work of cultural interest is important both from the microclimatic point of view and from the structural one. Elastic and plastic deformations, due to phenomena of heat exchange, influence, in a significant way, the mechanical behavior of the structure. Dealing with objects exposed to open air, one of the main sources of heat radiation is, obviously, the sun. Consequently, it is significant to evaluate the importance that solar radiation has in the global heating dynamics of the structure. Therefore, while studying the system Marcus Aurelius- Capitolium square, it was decided to support the investigations in situ (carried out by using thermovision and thermocouples) with the realization, on computer, of a system that could define the theoretical relationship existing between solar dynamics and the bronze monument. Correlation between information deduced from such a model and data obtained in situ, gave useful results and constituted a significant instrument for the analysis of the concrete thermal model of the investigated structure. The opportunity to deepen and improve such an experience arose when the Soprintendenza per i Beni Architettonici ed Ambientali di Firenze e Pistoia asked for a contribution to the studies and investigations aimed to define the thermal model of the Dome of Santa Maria del Fiore.

Removal of PCB and other halogenated organic contaminants found in ex situ structures

Science.gov (United States)

Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Geiger, Cherie L. (Inventor); Coon, Christina (Inventor); Filipek, Laura B. (Inventor); Berger, Cristina M. (Inventor); Milum, Kristen M. (Inventor)

2009-01-01

Emulsified systems of a surfactant-stabilized, biodegradable water-in-solvent emulsion with bimetallic particles contained with the emulsion droplets are useful at removing PCBs from ex situ structures. The hydrophobic emulsion system draws PCBs through the solvent/surfactant membrane. Once inside the membrane, the PCBs diffuse into the bimetallic particles and undergo degradation. The PCBs continue to enter, diffuse, degrade, and biphenyl will exit the particle maintaining a concentration gradient across the membrane and maintaining a driving force of the reaction.

Structure and Functions of Linker Histones.

Science.gov (United States)

Lyubitelev, A V; Nikitin, D V; Shaytan, A K; Studitsky, V M; Kirpichnikov, M P

2016-03-01

Linker histones such as variants H1, H5, and other similar proteins play an important role in regulation of chromatin structure and dynamics. However, interactions of linker histones with DNA and proteins, as well as specific functions of their different variants, are poorly studied. This is because they acquire tertiary structure only when interacting with a nucleosome, and because of limitations of currently available methods. However, deeper investigation of linker histones and their interactions with other proteins will address a number of important questions - from structure of compacted chromatin to regulation of early embryogenesis. In this review, structures of histone H1 variants and its interaction with chromatin DNA are considered. A possible functional significance of different H1 variants, a role of these proteins in maintaining interphase chromatin structure, and interactions of linker histones with other cellular proteins are also discussed.

In Situ Raman Spectroscopy of Supported Chromium Oxide Catalysts: Reactivity Studies with Methanol and Butane

NARCIS (Netherlands)

Weckhuysen, B.M.; Wachs, I.E.

1996-01-01

The interactions of methanol and butane with supported chromium oxide catalysts under oxidizing and reducing conditions were studied by in situ Raman spectroscopy as a function of the specific oxide support (Al2O3, ZrO2, TiO2, SiO2, Nb2O5, 3% SiO2/TiO2, 3% TiO2/SiO2, and a physical mixture of SiO2

In situ study of the growth and degradation processes in tetragonal lysozyme crystals on a silicon substrate by high-resolution X-ray diffractometry

Science.gov (United States)

Kovalchuk, M. V.; Prosekov, P. A.; Marchenkova, M. A.; Blagov, A. E.; D'yakova, Yu. A.; Tereshchenko, E. Yu.; Pisarevskii, Yu. V.; Kondratev, O. A.

2014-09-01

The results of an in situ study of the growth of tetragonal lysozyme crystals by high-resolution X-ray diffractometry are considered. The crystals are grown by the sitting-drop method on crystalline silicon substrates of different types: both on smooth substrates and substrates with artificial surface-relief structures using graphoepitaxy. The crystals are grown in a special hermetically closed crystallization cell, which enables one to obtain images with an optical microscope and perform in situ X-ray diffraction studies in the course of crystal growth. Measurements for lysozyme crystals were carried out in different stages of the crystallization process, including crystal nucleation and growth, developed crystals, the degradation of the crystal structure, and complete destruction.

Calculations of nucleon structure functions

International Nuclear Information System (INIS)

Signal, A.I.

1990-01-01

We present a method of calculating deep inelastic nucleon structure functions using bag model wavefunctions. Our method uses the Peierls - Yoccoz projection to form translation invariant bag states. We obtain the correct support for the structure functions and satisfy the positivity requirements for quark and anti-quark distribution functions. (orig.)

Informing conservation management about structural versus functional connectivity: a case-study of Cross River gorillas.

Science.gov (United States)

Imong, Inaoyom; Robbins, Martha M; Mundry, Roger; Bergl, Richard; Kühl, Hjalmar S

2014-10-01

Connectivity among subpopulations is vital for the persistence of small and fragmented populations. For management interventions to be effective conservation planners have to make the critical distinction between structural connectivity (based on landscape structure) and functional connectivity (which considers both landscape structure and organism-specific behavioral attributes) which can differ considerably within a given context. We assessed spatial and temporal changes in structural and functional connectivity of the Cross River gorilla Gorilla gorilla diehli (CRG) population in a 12,000 km(2) landscape in the Nigeria-Cameroon border region over a 23-year period, comparing two periods: 1987-2000 and 2000-2010. Despite substantial forest connections between occupied areas, genetic evidence shows that only limited dispersal occurs among CRG subpopulations. We used remotely sensed land-cover data and simulated human pressure (using a spatially explicit agent-based model) to assess human impact on connectivity of the CRG population. We calculated cost-weighted distances between areas occupied by gorillas as measures of connectivity (structural based on land-cover only, functional based on both land-cover and simulated human pressure). Whereas structural connectivity decreased by 5% over the 23-year period, functional connectivity decreased by 11%, with both decreasing more during the latter compared to the earlier period. Our results highlight the increasing threat of isolation of CRG subpopulations due to human disturbance, and provide insight into how increasing human influence may lead to functional isolation of wildlife populations despite habitat continuity, a pressing and common issue in tropical Africa often not accounted for when deciding management interventions. In addition to quantifying threats to connectivity, our study provides crucial evidence for management authorities to identify actions that are more likely to be effective for conservation of

Functional and Structural Network Recovery after Mild Traumatic Brain Injury: A 1-Year Longitudinal Study

Directory of Open Access Journals (Sweden)

Patrizia Dall’Acqua

2017-05-01

Full Text Available Brain connectivity after mild traumatic brain injury (mTBI has not been investigated longitudinally with respect to both functional and structural networks together within the same patients, crucial to capture the multifaceted neuropathology of the injury and to comprehensively monitor the course of recovery and compensatory reorganizations at macro-level. We performed a prospective study with 49 mTBI patients at an average of 5 days and 1 year post-injury and 49 healthy controls. Neuropsychological assessments as well as resting-state functional and diffusion-weighted magnetic resonance imaging were obtained. Functional and structural connectome analyses were performed using network-based statistics. They included a cross-sectional group comparison and a longitudinal analysis with the factors group and time. The latter tracked the subnetworks altered at the early phase and, in addition, included a whole-brain group × time interaction analysis. Finally, we explored associations between the evolution of connectivity and changes in cognitive performance. The early phase of mTBI was characterized by a functional hypoconnectivity in a subnetwork with a large overlap of regions involved within the classical default mode network. In addition, structural hyperconnectivity in a subnetwork including central hub areas such as the cingulate cortex was found. The impaired functional and structural subnetworks were strongly correlated and revealed a large anatomical overlap. One year after trauma and compared to healthy controls we observed a partial normalization of both subnetworks along with a considerable compensation of functional and structural connectivity subsequent to the acute phase. Connectivity changes over time were correlated with improvements in working memory, divided attention, and verbal recall. Neuroplasticity-induced recovery or compensatory processes following mTBI differ between brain regions with respect to their time course and are

Nucleon structure functions

International Nuclear Information System (INIS)

Virchaux, M.

1992-11-01

The present status of experimental measurements of the nucleon structure functions is reviewed. The results from nearly all deep inelastic experiments are in good mutual agreement. Principles of the analysis of these structure function data in the framework of QCD are described. The specific features of the perturbative QCD predictions are observed in the data. This provides quantitative tests of the validity of QCD as well as determinations of the various parton distributions in the nucleon and some of the most precise measurements of the strong coupling constant αs. The future of this field of experimental physics is sketched

Insight into the structure of Pd/ZrO2 during the total oxidation of methane using combined in situ XRD, X.-ray absorption and Raman spectroscopy

DEFF Research Database (Denmark)

Grunwaldt, Jan-Dierk; van Vegten, Niels; Baiker, Alfons

2009-01-01

The structure of palladium during the total combustion of methane has been studied by a combination of the complementary in situ techniques X-ray absorption spectroscopy, Raman spectroscopy and X-ray diffraction. The study demonstrates that finely dispersed and oxidized palladium is most active f...

In-situ Non-destructive Studies on Biofouling Processes in Reverse Osmosis Membrane Systems

KAUST Repository

Farhat, Nadia

2016-12-01

Reverse osmosis (RO) and nanofiltration (NF) membrane systems are high-pressure membrane filtration processes that can produce high quality drinking water. Biofouling, biofilm formation that exceeds a certain threshold, is a major problem in spiral wound RO and NF membrane systems resulting in a decline in membrane performance, produced water quality, and quantity. In practice, detection of biofouling is typically done indirectly through measurements of performance decline. Existing direct biofouling detection methods are mainly destructive, such as membrane autopsies, where biofilm samples can be contaminated, damaged and resulting in biofilm structural changes. The objective of this study was to test whether transparent luminescent planar oxygen sensing optodes, in combination with a simple imaging system, can be used for in-situ, non-destructive biofouling characterization. Aspects of the study were early detection of biofouling, biofilm spatial patterning in spacer filled channels, and the effect of feed cross-flow velocity, and feed flow temperature. Oxygen sensing optode imaging was found suitable for studying biofilm processes and gave detailed spatial and quantitative biofilm development information enabling better understanding of the biofouling development process. The outcome of this study attests the importance of in-situ, non-destructive imaging in acquiring detailed knowledge on biofilm development in membrane systems contributing to the development of effective biofouling control strategies.

Synchrotron x-ray methods in studies of thin organic film structure

International Nuclear Information System (INIS)

Gentle, I.

2002-01-01

Full text: In recent years, the study of the structures of organic films as thin as a single monolayer has been revolutionized by methods that take advantage of the characteristics of synchrotron radiation. In particular, the methods of grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity have led to a number of valuable insights into structural aspects of thin films at molecular resolution. Our group has been studying films formed at the air/water interface as insoluble monolayers and subsequently transferred to solid substrates using either the vertical (Langmuir-Blodgett) or horizontal (Langmuir-Schaeffer) methods. The main aim of these experiments is to exert control over film structure in the direction parallel to the substrate surface. This is highly desirable in order to design devices that exploit the optical and electrooptical properties of functional materials, but is difficult to do. By varying the chemical structure of the film materials and controlling deposition conditions a degree of control is possible, but only using synchrotron methods can it be easily verified. We have also developed a novel method of rapidly collecting data from GIXD measurements by the application of area detection (imaging plates), which has made possible measurements of dynamic processes such as in-situ annealing. Such measurements are not possible using traditional scanning methods. One area of current interest is films composed of porphyrins as functional materials, either alone or as mixed films with fatty acids. We have been investigating ways of assembling porphyrins in such a way as to overcome the tendency to aggregate, and to produce patterning and ordered structures in the plane of the interface. Examples will be given of how film composition and deposition method affects the final structure, and of how X-ray methods can be used to elucidate both the structures and the mechanisms. Copyright (2002) Australian X-ray Analytical Association Inc

Chromatin Structure and Function

CERN Document Server

Wolffe, Alan P

1999-01-01

The Third Edition of Chromatin: Structure and Function brings the reader up-to-date with the remarkable progress in chromatin research over the past three years. It has been extensively rewritten to cover new material on chromatin remodeling, histone modification, nuclear compartmentalization, DNA methylation, and transcriptional co-activators and co-repressors. The book is written in a clear and concise fashion, with 60 new illustrations. Chromatin: Structure and Function provides the reader with a concise and coherent account of the nature, structure, and assembly of chromatin and its active

Using ATR-FT/IR to detect carbohydrate-related molecular structure features of carinata meal and their in situ residues of ruminal fermentation in comparison with canola meal

Science.gov (United States)

Xin, Hangshu; Yu, Peiqiang

2013-10-01

There is no information on the co-products from carinata bio-fuel and bio-oil processing (carinata meal) in molecular structural profiles mainly related to carbohydrate biopolymers in relation to ruminant nutrition. Molecular analyses with Fourier transform infrared spectroscopy (FT/IR) technique with attenuated total reflectance (ATR) and chemometrics enable to detect structural features on a molecular basis. The objectives of this study were to: (1) determine carbohydrate conformation spectral features in original carinata meal, co-products from bio-fuel/bio-oil processing; and (2) investigate differences in carbohydrate molecular composition and functional group spectral intensities after in situ ruminal fermentation at 0, 12, 24 and 48 h compared to canola meal as a reference. The molecular spectroscopic parameters of carbohydrate profiles detected were structural carbohydrates (STCHO, mainly associated with hemi-cellulosic and cellulosic compounds; region and baseline ca. 1483-1184 cm-1), cellulosic compounds (CELC, region and baseline ca. 1304-1184 cm-1), total carbohydrates (CHO, region and baseline ca. 1193-889 cm-1) as well as the spectral ratios calculated based on respective spectral intensity data. The results showed that the spectral profiles of carinata meal were significantly different from that of canola meal in CHO 2nd peak area (center at ca. 1091 cm-1, region: 1102-1083 cm-1) and functional group peak intensity ratios such as STCHO 1st peak (ca. 1415 cm-1) to 2nd peak (ca. 1374 cm-1) height ratio, CHO 1st peak (ca. 1149 cm-1) to 3rd peak (ca. 1032 cm-1) height ratio, CELC to total CHO area ratio and STCHO to CELC area ratio, indicating that carinata meal may not in full accord with canola meal in carbohydrate utilization and availability in ruminants. Carbohydrate conformation and spectral features were changed by significant interaction of meal type and incubation time and almost all the spectral parameters were significantly decreased (P

In situ transmission electron microscope observation of the formation of fuzzy structures on tungsten

International Nuclear Information System (INIS)

Miyamoto, M; Watanabe, T; Nagashima, H; Nishijima, D; Doerner, R P; Krasheninnikov, S I; Sagara, A; Yoshida, N

2014-01-01

To investigate the formation processes of tungsten nano-structures, so called fuzz, in situ transmission electron microscope observations during helium ion irradiation and high temperature annealing have been performed. The irradiation with 3 keV He + from room temperature to 1273 K is found to cause high-density helium bubbles in tungsten with no significant change in the surface structure. At higher temperatures, surface morphology changes were observed even without helium irradiation due probably to surface diffusion of tungsten atoms driven by surface tension. It is clearly shown that this morphology change is enhanced with helium irradiation, i.e. the formation of helium bubbles. (paper)

Heterologous expression of plasmodial proteins for structural studies and functional annotation

CSIR Research Space (South Africa)

Birkholtz, LM

2008-01-01

Full Text Available Malaria Journal Open AcceReview Heterologous expression of plasmodial proteins for structural studies and functional annotation Lyn-Marie Birkholtz1, Gregory Blatch2, Theresa L Coetzer3, Heinrich C Hoppe1,4, Esmaré Human1, Elizabeth J Morris1,5, Zoleka Ngcete..., Kwadlangezwa, South Africa Email: Lyn-Marie Birkholtz - lbirkholtz@up.ac.za; Gregory Blatch - G.Blatch@ru.ac.za; Theresa L Coetzer - theresa.coetzer@nhls.ac.za; Heinrich C Hoppe - hhoppe@csir.co.za; Esmaré Human - esmare.human@up.ac.za; Elizabeth J Morris...

Exposure to contaminated sediments induces alterations in the gill epithelia in juvenile Solea senegalensis: a comparative in situ and ex situ study

Directory of Open Access Journals (Sweden)

Carla Martins

2014-06-01

contaminated sediments. Hypertrophied chloride cells are a consequence of a hindered osmotic regulation by the impairment of ionic active transport, leading to loss-of-function and excessive fluid retention in the cytoplasm. On its turn, a reduction in number and size of gill mucous cells likely reduced the protection provided by mucous to these delicate structures. In general, the alterations were more pronounced in the ex situ study than in situ bioassays, which is probably linked to differences in contaminant bioavailability between laboratory and field scenarios. This variation is likely related to, for instance, estuarine hydrodynamics and sediment steady-state parameters. Interestingly, the results suggest that time of exposure is a key factor, since fewer alterations were observed in animals sampled at the end of the assay (28 days compared to the mid-term (14 days, revealing adaptation to toxicological challenge. In conclusion, mixed sediment contamination can cause physiological alterations in fish gill epithelia that can be determined histologically. These subtle changes may affect the health status of animals by impairing key vital functions such as osmotic balance. As such, physiological alterations to fish gill epithelia may reflect, as in the present case, estuarine sediment contamination even when severe gill lesions are reduced or absent, which mandates caution when interpreting histopathological data in fish for the purpose of environmental risk assessment.

A Pilot Study On A Moment Carrying Beam-column Connection For Precast Structures

OpenAIRE

Kaplan, Vedat

2010-01-01

In this study, a moment carrying beam-column connection detail for precast structures has been investigated in the experimental and analytical manner. The 1/2 scaled beam-column test specimen is representing a real exterior precast connection detail. The cast-in-situ welded connection is applied at bottom face of the beams and additional re-bars and cast-in-situ concrete is introduced at the upper part of the beams. The experimental study is conducted in the form of varying beam top diplaceme...

Two US EPA bioremediation field initiative studies: Evaluation of in-situ bioventing

International Nuclear Information System (INIS)

Sayles, G.D.; Brenner, R.C.; Hinchee, R.E.; Vogel, C.M.; Miller, R.N.

1992-01-01

Bioventing is the process of supplying oxygen in-situ to oxygen-deprived soil microbes by forcing air through contaminated soil at low air flow rates. Unlike soil venting or soil vacuum extraction technologies, bioventing attempts to stimulate biodegradative activity while minimizing stripping of volatile organics. The process destroys the toxic compounds in the ground. Bioventing technology is especially valuable for treating contaminated soils in areas where structures and utilities cannot be disturbed because the equipment needed (air injection/withdrawal wells, air blower, and soil gas monitoring wells) is relatively non-invasive. The US EPA Risk Reduction Engineering Laboratory, with resources from the US EPA Bioremediation Field Initiative, began two parallel 2-year field studies of in-situ of 1991 in collaboration with the US Air Force. The field sites are located at Eielson Air Force Base (AFB) near Fairbanks, Alaska, and Hill AFB near Salt Lake City, Utah. Each site has jet fuel JP-4 contaminated unsaturated soil where a spill has occurred in association with a fuel distribution network. With the pilot-scale experience gained in these studies and others, bioventing should be available in the very near future as an inexpensive, unobtrusive means of treating large quantities of organically contaminated soils. 5 figs

In-situ white beam microdiffraction study of the deformation behavior in polycrystalline magnesium alloy during uniaxial loading

International Nuclear Information System (INIS)

Advanced Light Source; Tamura, Nobumichi; Lynch, P.A.; Stevenson, A.W.; Liang, D.; Parry, D.; Wilkins, S.; Madsen, I.C.; Bettles, C.; Tamura, N.; Geandier, G.

2007-01-01

Scanning white beam X-ray microdiffraction has been used to study the heterogeneous grain deformation in a polycrystalline Mg alloy (MgAZ31). The high spatial resolution achieved on beamline 7.3.3 at the Advanced Light Source provides a unique method to measure the elastic strain and orientation of single grains as a function of applied load. To carry out in-situ measurements a light weight (∼0.5kg) tensile stage, capable of providing uniaxial loads of up to 600kg, was designed to collect diffraction data on the loading and unloading cycle. In-situ observation of the deformation process provides insight about the crystallographic deformation mode via twinning and dislocation slip

Function and Evolutionary Origin of Unicellular Camera-Type Eye Structure

KAUST Repository

Hayakawa, Shiho

2015-03-03

The ocelloid is an extraordinary eyespot organelle found only in the dinoflagellate family Warnowiaceae. It contains retina- and lens-like structures called the retinal body and the hyalosome. The ocelloid has been an evolutionary enigma because of its remarkable resemblance to the multicellular camera-type eye. To determine if the ocelloid is functionally photoreceptive, we investigated the warnowiid dinoflagellate Erythropsidinium. Here, we show that the morphology of the retinal body changed depending on different illumination conditions and the hyalosome manifests the refractile nature. Identifying a rhodopsin gene fragment in Erythropsidinium ESTs that is expressed in the retinal body by in situ hybridization, we also show that ocelloids are actually light sensitive photoreceptors. The rhodopsin gene identified is most closely related to bacterial rhodopsins. Taken together, we suggest that the ocelloid is an intracellular camera-type eye, which might be originated from endosymbiotic origin. © 2015 Hayakawa et al.

Function and Evolutionary Origin of Unicellular Camera-Type Eye Structure

KAUST Repository

Hayakawa, Shiho; Takaku, Yasuharu; Hwang, Jung Shan; Horiguchi, Takeo; Suga, Hiroshi; Gehring, Walter; Ikeo, Kazuho; Gojobori, Takashi

2015-01-01

The ocelloid is an extraordinary eyespot organelle found only in the dinoflagellate family Warnowiaceae. It contains retina- and lens-like structures called the retinal body and the hyalosome. The ocelloid has been an evolutionary enigma because of its remarkable resemblance to the multicellular camera-type eye. To determine if the ocelloid is functionally photoreceptive, we investigated the warnowiid dinoflagellate Erythropsidinium. Here, we show that the morphology of the retinal body changed depending on different illumination conditions and the hyalosome manifests the refractile nature. Identifying a rhodopsin gene fragment in Erythropsidinium ESTs that is expressed in the retinal body by in situ hybridization, we also show that ocelloids are actually light sensitive photoreceptors. The rhodopsin gene identified is most closely related to bacterial rhodopsins. Taken together, we suggest that the ocelloid is an intracellular camera-type eye, which might be originated from endosymbiotic origin. © 2015 Hayakawa et al.

Structure functions of hadrons in the QCD effective theory

International Nuclear Information System (INIS)

Shigetani, Takayuki

1996-01-01

We study the structure functions of hadrons with the low energy effective theory of QCD. We try to clarify a link between the low energy effective theory, where non-perturbative dynamics is essential, and the high energy deep inelastic scattering experiment. We calculate the leading twist matrix elements of the structure function at the low energy model scale within the effective theory. Calculated structure functions are evoluted to the high momentum scale with the help of the perturbative QCD, and compared with the experimental data. Through the comparison of the model calculations with the experiment, we discuss how the non-perturbative dynamics of the effective theory is reflected in the deep inelastic phenomena. We first evaluate the structure functions of the pseudoscalar mesons using the NJL model. The resulting structure functions show reasonable agreements with experiments. We study then the quark distribution functions of the nucleon using a covariant quark-diquark model. We calculate three leading twist distribution functions, spin-independent f 1 (x), longitudinal spin distribution g 1 (x), and chiral-odd transversity spin distribution h 1 (x). The results for f 1 (x) and g 1 (x) turn out to be consistent with available experiments because of the strong spin-0 diquark correlation. (author)

In situ X-ray and neutron diffraction study of Ba2In2O5

International Nuclear Information System (INIS)

Speakman, S.A.; Misture, S.T.

2001-01-01

Order-disorder transitions in barium indate, Ba 2 In 2 O 5 , have been studied using in-situ X-ray and neutron diffraction. At room temperature, the crystal structure is an orthorhombic brownmillerite structure. At 706 C, the crystal structure is orthorhombic, possibly of the Imma or Ibm2 space groups. At 900 C, oxygen vacancies begin to disorder. The order-disorder transition occurs slowly in two steps over a temperature range of 900 - 925 C. Above this temperature range, the crystal structure is tetragonal, most likely belonging to the space group I 4/mcm. A second order-disorder transition begins at 1040 C, and proceeds over the temperature range 1040 - 1065 C. Above this temperature range, the crystal structure is a cubic, oxygen-deficient perovskite structure, with space group Pm3m. At an undetermined temperature above 1200 C, Ba 2 In 2 O 5 begins to decompose. (orig.)

Transparent, flexible surface enhanced Raman scattering substrates based on Ag-coated structured PET (polyethylene terephthalate) for in-situ detection

International Nuclear Information System (INIS)

Zuo, Zewen; Zhu, Kai; Gu, Chuan; Wen, Yibing; Cui, Guanglei; Qu, Jun

2016-01-01

Highlights: • Transparent, flexible SERS substrates were prepared using techniques compatible with well-established silicon device technologies. • The SERS substrates exhibit high sensitivity and good reproducibility. • The high performance is related with the quasi-three-dimensional structure of the PET. • In-situ detection of analyte on irregular objects was achieved by this SERS substrate. - Abstract: Transparent, flexible surface-enhanced Raman scattering (SERS) substrates were fabricated by metalization of structured polyethylene terephthalate (PET) sheets. The resultant Ag-coated structured PET SERS substrates were revealed to be highly sensitive with good reproducibility and stability, an enhancement factor of 3 × 10 6 was acquired, which can be attributed mainly to the presence of plentiful multiple-type hot spots within the quasi-three-dimensional surface of the structured PET obtained by oxygen plasma etching. In addition, detections of model molecules on fruit skin were also carried out, demonstrating the great potential of the Ag-coated structured PET in in-situ detection of analyte on irregular objects. Importantly, the technique used for the preparation of such substrate is completely compatible with well-established silicon device technologies, and large-area fabrication with low cost can be readily realized.

Transparent, flexible surface enhanced Raman scattering substrates based on Ag-coated structured PET (polyethylene terephthalate) for in-situ detection

Energy Technology Data Exchange (ETDEWEB)

Zuo, Zewen, E-mail: zuozewen@mail.ahnu.edu.cn; Zhu, Kai; Gu, Chuan; Wen, Yibing; Cui, Guanglei; Qu, Jun

2016-08-30

Highlights: • Transparent, flexible SERS substrates were prepared using techniques compatible with well-established silicon device technologies. • The SERS substrates exhibit high sensitivity and good reproducibility. • The high performance is related with the quasi-three-dimensional structure of the PET. • In-situ detection of analyte on irregular objects was achieved by this SERS substrate. - Abstract: Transparent, flexible surface-enhanced Raman scattering (SERS) substrates were fabricated by metalization of structured polyethylene terephthalate (PET) sheets. The resultant Ag-coated structured PET SERS substrates were revealed to be highly sensitive with good reproducibility and stability, an enhancement factor of 3 × 10{sup 6} was acquired, which can be attributed mainly to the presence of plentiful multiple-type hot spots within the quasi-three-dimensional surface of the structured PET obtained by oxygen plasma etching. In addition, detections of model molecules on fruit skin were also carried out, demonstrating the great potential of the Ag-coated structured PET in in-situ detection of analyte on irregular objects. Importantly, the technique used for the preparation of such substrate is completely compatible with well-established silicon device technologies, and large-area fabrication with low cost can be readily realized.

Association of Weight and Body Composition on Cardiac Structure and Function in the ARIC Study (Atherosclerosis Risk in Communities).

Science.gov (United States)

Bello, Natalie A; Cheng, Susan; Claggett, Brian; Shah, Amil M; Ndumele, Chiadi E; Roca, Gabriela Querejeta; Santos, Angela B S; Gupta, Deepak; Vardeny, Orly; Aguilar, David; Folsom, Aaron R; Butler, Kenneth R; Kitzman, Dalane W; Coresh, Josef; Solomon, Scott D

2016-08-01

Obesity increases cardiovascular risk. However, the extent to which various measures of body composition are associated with abnormalities in cardiac structure and function, independent of comorbidities commonly affecting obese individuals, is not clear. This study sought to examine the relationship between body mass index, waist circumference, and percent body fat with conventional and advanced measures of cardiac structure and function. We studied 4343 participants of the ARIC study (Atherosclerosis Risk in Communities) who were aged 69 to 82 years, free of coronary heart disease and heart failure, and underwent comprehensive echocardiography. Increasing body mass index, waist circumference, and body fat were associated with greater left ventricular (LV) mass and left atrial volume indexed to height(2.7) in both men and women (Pheart disease or heart failure, obesity was associated with subclinical abnormalities in cardiac structure in both men and women and with adverse LV remodeling and impaired LV systolic function in women. These data highlight the association of obesity and subclinical abnormalities of cardiac structure and function, particularly in women. © 2016 American Heart Association, Inc.

Tailoring the Electrochemical Properties of Carbon Nanotube Modified Indium Tin Oxide via in Situ Grafting of Aryl Diazonium.

Science.gov (United States)

Hicks, Jacqueline M; Wong, Zhi Yi; Scurr, David J; Silman, Nigel; Jackson, Simon K; Mendes, Paula M; Aylott, Jonathan W; Rawson, Frankie J

2017-05-23

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling in situ grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insights into the in situ grafting of diazonium. We discovered that the connecting bond is a nitro group which is covalently linked to a carbon on the aryl amine. The increased understanding of the surface chemistry gained through these studies enabled us to fabricate surfaces with optimized electron transfer kinetics. The knowledge gained from these studies allows for the rational design and tuning of the electronic properties of ITO-based conducting surfaces important for development of various electronic applications.

Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study

OpenAIRE

Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

2015-01-01

Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural high-resolution T1-weighted MRI; fMRI image...

Brain structure and the relationship with neurocognitive functioning in schizophrenia and bipolar disorder : MRI studies

OpenAIRE

Hartberg, Cecilie Bhandari

2011-01-01

Brain structural abnormalities as well as neurocognitive dysfunction, are found in schizophrenia and in bipolar disorder. Based on the fact that both brain structure and neurocognitive functioning are significantly heritable and affected in both schizophrenia and bipolar disorder, relationships between them are expected. However, previous studies report inconsistent findings. Also, schizophrenia and bipolar disorder are classified as separate disease entities, but demonstrate overlap with reg...

The structural and electronic properties of amine-functionalized boron nitride nanotubes via ammonia plasmas: a density functional theory study

International Nuclear Information System (INIS)

Cao Fenglei; Ji Yuemeng; Zhao Cunyuan; Ren Wei

2009-01-01

The reaction behavior of the chemical modification of boron nitride nanotubes (BNNTs) with ammonia plasmas has been investigated by density functional theory (DFT) calculations. Unlike previously studied functionalization with NH 3 and amino functional groups, we found that NH 2 * radicals involved in the ammonia plasmas can be covalently incorporated to BNNTs through a strong single B-N bond. Subsequently, the H * radicals also involved in the ammonia plasmas would prefer to combine with the N atoms neighboring the NH 2 -functionalized B atoms. Our study revealed that this reaction behavior can be elucidated using the frontier orbital theory. The calculated band structures and density of states (DOS) indicate that this modification is an effective method to modulate the electronic properties of BNNTs. We have discussed various defects on the surface of BNNTs generated by collisions of N 2 + ions. For most defects considered, the reactivity of the functionalization of BNNTs with NH 2 * are enhanced. Our conclusions are independent of the chirality, and the diameter dependence of the reaction energies is presented.

In situ scanning tunneling microscopy study of Ca-modified rutile TiO2(110 in bulk water

Directory of Open Access Journals (Sweden)

Giulia Serrano

2015-02-01

Full Text Available Despite the rising technological interest in the use of calcium-modified TiO2 surfaces in biomedical implants, the Ca/TiO2 interface has not been studied in an aqueous environment. This investigation is the first report on the use of in situ scanning tunneling microscopy (STM to study calcium-modified rutile TiO2(110 surfaces immersed in high purity water. The TiO2 surface was prepared under ultrahigh vacuum (UHV with repeated sputtering/annealing cycles. Low energy electron diffraction (LEED analysis shows a pattern typical for the surface segregation of calcium, which is present as an impurity on the TiO2 bulk. In situ STM images of the surface in bulk water exhibit one-dimensional rows of segregated calcium regularly aligned with the [001] crystal direction. The in situ-characterized morphology and structure of this Ca-modified TiO2 surface are discussed and compared with UHV-STM results from the literature. Prolonged immersion (two days in the liquid leads to degradation of the overlayer, resulting in a disordered surface. X-ray photoelectron spectroscopy, performed after immersion in water, confirms the presence of calcium.

Purely Functional Structured Programming

OpenAIRE

Obua, Steven

2010-01-01

The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this proposal is that m...

A Comparative Study on Optimal Structural Dynamics Using Wavelet Functions

Directory of Open Access Journals (Sweden)

Seyed Hossein Mahdavi

2015-01-01

Full Text Available Wavelet solution techniques have become the focus of interest among researchers in different disciplines of science and technology. In this paper, implementation of two different wavelet basis functions has been comparatively considered for dynamic analysis of structures. For this aim, computational technique is developed by using free scale of simple Haar wavelet, initially. Later, complex and continuous Chebyshev wavelet basis functions are presented to improve the time history analysis of structures. Free-scaled Chebyshev coefficient matrix and operation of integration are derived to directly approximate displacements of the corresponding system. In addition, stability of responses has been investigated for the proposed algorithm of discrete Haar wavelet compared against continuous Chebyshev wavelet. To demonstrate the validity of the wavelet-based algorithms, aforesaid schemes have been extended to the linear and nonlinear structural dynamics. The effectiveness of free-scaled Chebyshev wavelet has been compared with simple Haar wavelet and two common integration methods. It is deduced that either indirect method proposed for discrete Haar wavelet or direct approach for continuous Chebyshev wavelet is unconditionally stable. Finally, it is concluded that numerical solution is highly benefited by the least computation time involved and high accuracy of response, particularly using low scale of complex Chebyshev wavelet.

Proton and neutron structure functions

International Nuclear Information System (INIS)

Rock, S.

1991-01-01

New result on charged lepton scattering from hydrogen and deuterium targets by the BCDMS, NMC and SLAC collaborations have greatly increased our knowledge of the structure functions of protons and neutrons. The disagreement between the high energy muon scattering cross sections obtained by the EMC and BCDMS collaborations have been almost completely resolved by comparison with a global analysis of old and new SLAC data and a reanalysis of EMC data. We now have a consistent set of structure functions which covers an approximate range 1 ≤ Q 2 ≤ 200 (GeV/c) 2 and 0.07 ≤ x ≤ 0.7. The ratio of neutron to proton structure functions decreases with increasing Q 2 for values of x ≥ 0.1. The difference between proton and neutron structure functions approaches zero as x decreases, consistent with the expected √x behavior. (orig.)

Ex-situ and in-situ mineral carbonation as a means to sequester carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Gerdemann, Stephen J.; Dahlin, David C.; O' Connor, William K.; Penner, Larry R.; Rush, G.E.

2004-01-01

The U. S. Department of Energy's Albany Research Center is investigating mineral carbonation as a method of sequestering CO2 from coal-fired-power plants. Magnesium-silicate minerals such as serpentine [Mg3Si2O5(OH)4] and olivine (Mg2SiO4) react with CO2 to produce magnesite (MgCO3), and the calcium-silicate mineral, wollastonite (CaSiO3), reacts to form calcite (CaCO3). It is possible to carry out these reactions either ex situ (above ground in a traditional chemical processing plant) or in situ (storage underground and subsequent reaction with the host rock to trap CO2 as carbonate minerals). For ex situ mineral carbonation to be economically attractive, the reaction must proceed quickly to near completion. The reaction rate is accelerated by raising the activity of CO2 in solution, heat (but not too much), reducing the particle size, high-intensity grinding to disrupt the crystal structure, and, in the case of serpentine, heat-treatment to remove the chemically bound water. All of these carry energy/economic penalties. An economic study illustrates the impact of mineral availability and process parameters on the cost of ex situ carbon sequestration. In situ carbonation offers economic advantages over ex situ processes, because no chemical plant is required. Knowledge gained from the ex situ work was applied to long-term experiments designed to simulate in situ CO2 storage conditions. The Columbia River Basalt Group (CRBG), a multi-layered basaltic lava formation, has potentially favorable mineralogy (up to 25% combined concentration of Ca, Fe2+, and Mg cations) for storage of CO2. However, more information about the interaction of CO2 with aquifers and the host rock is needed. Core samples from the CRBG, as well as samples of olivine, serpentine, and sandstone, were reacted in an autoclave for up to 2000 hours at elevated temperatures and pressures. Changes in core porosity, secondary mineralizations, and both solution and solid chemistry were measured.

COBRA: A prospective multimodal imaging study of dopamine, brain structure and function, and cognition.

Science.gov (United States)

Nevalainen, N; Riklund, K; Andersson, M; Axelsson, J; Ögren, M; Lövdén, M; Lindenberger, U; Bäckman, L; Nyberg, L

2015-07-01

Cognitive decline is a characteristic feature of normal human aging. Previous work has demonstrated marked interindividual variability in onset and rate of decline. Such variability has been linked to factors such as maintenance of functional and structural brain integrity, genetics, and lifestyle. Still, few, if any, studies have combined a longitudinal design with repeated multimodal imaging and a comprehensive assessment of cognition as well as genetic and lifestyle factors. The present paper introduces the Cognition, Brain, and Aging (COBRA) study, in which cognitive performance and brain structure and function are measured in a cohort of 181 older adults aged 64 to 68 years at baseline. Participants will be followed longitudinally over a 10-year period, resulting in a total of three equally spaced measurement occasions. The measurement protocol at each occasion comprises a comprehensive set of behavioral and imaging measures. Cognitive performance is evaluated via computerized testing of working memory, episodic memory, perceptual speed, motor speed, implicit sequence learning, and vocabulary. Brain imaging is performed using positron emission tomography with [(11)C]-raclopride to assess dopamine D2/D3 receptor availability. Structural magnetic resonance imaging (MRI) is used for assessment of white and gray-matter integrity and cerebrovascular perfusion, and functional MRI maps brain activation during rest and active task conditions. Lifestyle descriptives are collected, and blood samples are obtained and stored for future evaluation. Here, we present selected results from the baseline assessment along with a discussion of sample characteristics and methodological considerations that determined the design of the study. This article is part of a Special Issue entitled SI: Memory & Aging. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Cardiac structure and function predicts functional decline in the oldest old.

Science.gov (United States)

Leibowitz, David; Jacobs, Jeremy M; Lande-Stessman, Irit; Gilon, Dan; Stessman, Jochanan

2018-02-01

Background This study examined the association between cardiac structure and function and the deterioration in activities of daily living (ADLs) in an age-homogenous, community-dwelling population of patients born in 1920-1921 over a five-year follow-up period. Design Longitudinal cohort study. Methods Patients were recruited from the Jerusalem Longitudinal Cohort Study, which has followed an age-homogenous cohort of Jerusalem residents born in 1920-1921. Patients underwent home echocardiography and were followed up for five years. Dependence was defined as needing assistance with one or more basic ADL. Standard echocardiographic assessment of cardiac structure and function, including systolic and diastolic function, was performed. Reassessment of ADLs was performed at the five-year follow-up. Results A total of 459 patients were included in the study. Of these, 362 (79%) showed a deterioration in at least one ADL at follow-up. Patients with functional deterioration had a significantly higher left ventricular mass index and left atrial volume with a lower ejection fraction. There was no significant difference between the diastolic parameters the groups in examined. When the data were examined categorically, a significantly larger percentage of patients with functional decline had an abnormal left ventricular ejection fraction and left ventricular hypertrophy. The association between left ventricular mass index and functional decline remained significant in all multivariate models. Conclusions In this cohort of the oldest old, an elevated left ventricular mass index, higher left atrial volumes and systolic, but not diastolic dysfunction, were predictive of functional disability.

WIPP/SRL in-situ tests

International Nuclear Information System (INIS)

Mamsey, W.G.

1990-01-01

The Materials Interface Interactions Test (MIIT) is the only in-situ program involving the burial of simulated high-level waste forms operating in the United States. Fifteen glass and waste form compositions and their proposed package materials, supplied by 7 countries, are interred in salt at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. A joint effort between Sandia National Laboratories and Savannah River Laboratory, MIIT is the largest international cooperative in-situ venture yet undertaken. The objective of the current study is to document the waste form compositions used in the MIIT program and then to examine compositional correlations based on structural considerations, bonding energies, and surface layer formation. These correlations show important similarities between the many different waste glass compositions studied world wide and suggest that these glasses would be expected to perform well and in a similar manner

Structure of the Human Mitochondrial Ribosome Studied In Situ by Cryoelectron Tomography.

Science.gov (United States)

Englmeier, Robert; Pfeffer, Stefan; Förster, Friedrich

2017-10-03

Mitochondria maintain their own genome and its corresponding protein synthesis machine, the mitochondrial ribosome (mitoribosome). Mitoribosomes primarily synthesize highly hydrophobic proteins of the inner mitochondrial membrane. Recent studies revealed the complete structure of the isolated mammalian mitoribosome, but its mode of membrane association remained hypothetical. In this study, we used cryoelectron tomography to visualize human mitoribosomes in isolated mitochondria. The subtomogram average of the membrane-associated human mitoribosome reveals a single major contact site with the inner membrane, mediated by the mitochondria-specific protein mL45. A second rRNA-mediated contact site that is present in yeast is absent in humans, resulting in a more variable association of the human mitoribosome with the inner membrane. Despite extensive structural differences of mammalian and fungal mitoribosomal structure, the principal organization of peptide exit tunnel and the mL45 homolog remains invariant, presumably to align the mitoribosome with the membrane-embedded insertion machinery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Significance tests for functional data with complex dependence structure.

Science.gov (United States)

Staicu, Ana-Maria; Lahiri, Soumen N; Carroll, Raymond J

2015-01-01

We propose an L 2 -norm based global testing procedure for the null hypothesis that multiple group mean functions are equal, for functional data with complex dependence structure. Specifically, we consider the setting of functional data with a multilevel structure of the form groups-clusters or subjects-units, where the unit-level profiles are spatially correlated within the cluster, and the cluster-level data are independent. Orthogonal series expansions are used to approximate the group mean functions and the test statistic is estimated using the basis coefficients. The asymptotic null distribution of the test statistic is developed, under mild regularity conditions. To our knowledge this is the first work that studies hypothesis testing, when data have such complex multilevel functional and spatial structure. Two small-sample alternatives, including a novel block bootstrap for functional data, are proposed, and their performance is examined in simulation studies. The paper concludes with an illustration of a motivating experiment.

Significance tests for functional data with complex dependence structure

KAUST Repository

Staicu, Ana-Maria

2015-01-01

We propose an L (2)-norm based global testing procedure for the null hypothesis that multiple group mean functions are equal, for functional data with complex dependence structure. Specifically, we consider the setting of functional data with a multilevel structure of the form groups-clusters or subjects-units, where the unit-level profiles are spatially correlated within the cluster, and the cluster-level data are independent. Orthogonal series expansions are used to approximate the group mean functions and the test statistic is estimated using the basis coefficients. The asymptotic null distribution of the test statistic is developed, under mild regularity conditions. To our knowledge this is the first work that studies hypothesis testing, when data have such complex multilevel functional and spatial structure. Two small-sample alternatives, including a novel block bootstrap for functional data, are proposed, and their performance is examined in simulation studies. The paper concludes with an illustration of a motivating experiment.

In situ observation of structural change of nanostructured tungsten during annealing

International Nuclear Information System (INIS)

Yajima, Miyuki; Yoshida, Naoaki; Kajita, Shin; Tokitani, Masayuki; Baba, Tomotsugu; Ohno, Noriyasu

2014-01-01

Deformation of fiberform nanostructure and the dynamic behavior of helium (He) bubbles in fuzz tungsten (W) during annealing have been investigated by means of in situ cross-section observation using transmission electron microscopy and He desorption rate observation using thermal desorption spectroscopy (TDS). Thermal recovery of the nanostructure, such as shrinkage and coalescence of fine structure, annihilation of He bubbles, and large desorption of He gas, occurred around 1073–1173 K. The activation energy of He was estimated from a TDS peak that appeared around 300–400 K by using the Kissinger–Akahira–Sunose model-free-kinetics method. In addition, the TDS results of fiberform nanostructured tungsten were compared with those of tungsten samples irradiated with a high-energy He ion beam

Structure to function: Spider silk and human collagen

Science.gov (United States)

Rabotyagova, Olena S.

Nature has the ability to assemble a variety of simple molecules into complex functional structures with diverse properties. Collagens, silks and muscles fibers are some examples of fibrous proteins with self-assembling properties. One of the great challenges facing Science is to mimic these designs in Nature to find a way to construct molecules that are capable of organizing into functional supra-structures by self-assembly. In order to do so, a construction kit consisting of molecular building blocks along with a complete understanding on how to form functional materials is required. In this current research, the focus is on spider silk and collagen as fibrous protein-based biopolymers that can shed light on how to generate nanostructures through the complex process of self-assembly. Spider silk in fiber form offers a unique combination of high elasticity, toughness, and mechanical strength, along with biological compatibility and biodegrability. Spider silk is an example of a natural block copolymer, in which hydrophobic and hydrophilic blocks are linked together generating polymers that organize into functional materials with extraordinary properties. Since silks resemble synthetic block copolymer systems, we adopted the principles of block copolymer design from the synthetic polymer literature to build block copolymers based on spider silk sequences. Moreover, we consider spider silk to be an important model with which to study the relationships between structure and properties in our system. Thus, the first part of this work was dedicated to a novel family of spider silk block copolymers, where we generated a new family of functional spider silk-like block copolymers through recombinant DNA technology. To provide fundamental insight into relationships between peptide primary sequence, block composition, and block length and observed morphological and structural features, we used these bioengineered spider silk block copolymers to study secondary structure

Genomics and structure/function studies of Rhabdoviridae proteins involved in replication and transcription.

Science.gov (United States)

Assenberg, R; Delmas, O; Morin, B; Graham, S C; De Lamballerie, X; Laubert, C; Coutard, B; Grimes, J M; Neyts, J; Owens, R J; Brandt, B W; Gorbalenya, A; Tucker, P; Stuart, D I; Canard, B; Bourhy, H

2010-08-01

Some mammalian rhabdoviruses may infect humans, and also infect invertebrates, dogs, and bats, which may act as vectors transmitting viruses among different host species. The VIZIER programme, an EU-funded FP6 program, has characterized viruses that belong to the Vesiculovirus, Ephemerovirus and Lyssavirus genera of the Rhabdoviridae family to perform ground-breaking research on the identification of potential new drug targets against these RNA viruses through comprehensive structural characterization of the replicative machinery. The contribution of VIZIER programme was of several orders. First, it contributed substantially to research aimed at understanding the origin, evolution and diversity of rhabdoviruses. This diversity was then used to obtain further structural information on the proteins involved in replication. Two strategies were used to produce recombinant proteins by expression of both full length or domain constructs in either E. coli or insect cells, using the baculovirus system. In both cases, parallel cloning and expression screening at small-scale of multiple constructs based on different viruses including the addition of fusion tags, was key to the rapid generation of expression data. As a result, some progress has been made in the VIZIER programme towards dissecting the multi-functional L protein into components suitable for structural and functional studies. However, the phosphoprotein polymerase co-factor and the structural matrix protein, which play a number of roles during viral replication and drives viral assembly, have both proved much more amenable to structural biology. Applying the multi-construct/multi-virus approach central to protein production processes in VIZIER has yielded new structural information which may ultimately be exploitable in the derivation of novel ways of intervening in viral replication. Copyright 2010 Elsevier B.V. All rights reserved.

Altered contralateral sensorimotor system organization after experimental hemispherectomy: a structural and functional connectivity study.

Science.gov (United States)

Otte, Willem M; van der Marel, Kajo; van Meer, Maurits P A; van Rijen, Peter C; Gosselaar, Peter H; Braun, Kees P J; Dijkhuizen, Rick M

2015-08-01

Hemispherectomy is often followed by remarkable recovery of cognitive and motor functions. This reflects plastic capacities of the remaining hemisphere, involving large-scale structural and functional adaptations. Better understanding of these adaptations may (1) provide new insights in the neuronal configuration and rewiring that underlies sensorimotor outcome restoration, and (2) guide development of rehabilitation strategies to enhance recovery after hemispheric lesioning. We assessed brain structure and function in a hemispherectomy model. With MRI we mapped changes in white matter structural integrity and gray matter functional connectivity in eight hemispherectomized rats, compared with 12 controls. Behavioral testing involved sensorimotor performance scoring. Diffusion tensor imaging and resting-state functional magnetic resonance imaging were acquired 7 and 49 days post surgery. Hemispherectomy caused significant sensorimotor deficits that largely recovered within 2 weeks. During the recovery period, fractional anisotropy was maintained and white matter volume and axial diffusivity increased in the contralateral cerebral peduncle, suggestive of preserved or improved white matter integrity despite overall reduced white matter volume. This was accompanied by functional adaptations in the contralateral sensorimotor network. The observed white matter modifications and reorganization of functional network regions may provide handles for rehabilitation strategies improving functional recovery following large lesions.

Regge behaviour of structure functions and evolution of gluon structure function upto next-to-leading order at low-x

International Nuclear Information System (INIS)

Jamil, U.; Sarma, J.K.

2011-01-01

Evolution of gluon structure function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations upto next-to-leading order at low-x is presented assuming the Regge behaviour of structure functions. We compare our results of gluon structure function with GRV 98 global parameterization and show the compatibility of Regge behaviour of structure functions with PQCD. (author)

SERAT HARDAMUDHA IN JAVANESE LITERATURE: A STUDY OF STRUCTURE, FUNCTION AND MEANING

Directory of Open Access Journals (Sweden)

Kamidjan Kamidjan

2013-02-01

Full Text Available In this study Serat Hardamudha written by Kyai Secanitis is chosen as the object of the study. It is part of a collection at the Sonobudoyo Museum, Yogyakarta, with No. PB A 244 as its collection number. It contains symbols and signs which attracts the researcher’s attention. Such signs can be interpreted as social, moral, religious, and cultural teachings which are so great that they may be utilized as a learning medium in our lives. The problems in this study are formulated as follows: (1 what is the structure of Serta Hardamudha like; (2 what are its functions for our lives; and (3 what meanings it contains? This study aims at analyzing (1  the structure of Serat Hardamudha; (2  its functions for our lives; (3  its meanings. This study is classified as a qualitative one using qualitative data in the forms of words, sentences or concepts taken from the data sources.  The data were obtained from the primary and secondary sources. The primary data source in this study         is a literary work entitled Serat Hardamudha. The secondary data sources include references related to research. The data were collected using note taking technique completed with data cards and note books. The data were descriptively and interpretatively analyzed using hermeneutic approach. The novelties of the study are that (1 Serat Hardamudha deviated from conventions but contained innovations. From the form point of view, it, especially tembang Dhandhanggula, gatra 3, deviated from conventions. (2 The massage was symbolically and implicitly presented. (3 Serat Hardamudha presented the life of the Javanese people during colonial era. (4 Serat Hardamudha was written to give enlightenment to the community that ma lima should be eliminated.

A structural study for the optimisation of functional motifs encoded in protein sequences

Directory of Open Access Journals (Sweden)

Helmer-Citterich Manuela

2004-04-01

Full Text Available Abstract Background A large number of PROSITE patterns select false positives and/or miss known true positives. It is possible that – at least in some cases – the weak specificity and/or sensitivity of a pattern is due to the fact that one, or maybe more, functional and/or structural key residues are not represented in the pattern. Multiple sequence alignments are commonly used to build functional sequence patterns. If residues structurally conserved in proteins sharing a function cannot be aligned in a multiple sequence alignment, they are likely to be missed in a standard pattern construction procedure. Results Here we present a new procedure aimed at improving the sensitivity and/ or specificity of poorly-performing patterns. The procedure can be summarised as follows: 1. residues structurally conserved in different proteins, that are true positives for a pattern, are identified by means of a computational technique and by visual inspection. 2. the sequence positions of the structurally conserved residues falling outside the pattern are used to build extended sequence patterns. 3. the extended patterns are optimised on the SWISS-PROT database for their sensitivity and specificity. The method was applied to eight PROSITE patterns. Whenever structurally conserved residues are found in the surface region close to the pattern (seven out of eight cases, the addition of information inferred from structural analysis is shown to improve pattern selectivity and in some cases selectivity and sensitivity as well. In some of the cases considered the procedure allowed the identification of functionally interesting residues, whose biological role is also discussed. Conclusion Our method can be applied to any type of functional motif or pattern (not only PROSITE ones which is not able to select all and only the true positive hits and for which at least two true positive structures are available. The computational technique for the identification of

Solid oxide electrode kinetics in light of in situ surface studies

DEFF Research Database (Denmark)

Mogensen, Mogens Bjerg

2014-01-01

The combination of in situ and in particular in operando characterization methods such as electrochemical impedance spectroscopy (EIS) on both technical and model electrode are well known ways to gain some practical insight in electrode reaction kinetics. Yet, is has become clear that in spite...... of the strengths it is not sufficient to reveal much details of the electrode mechanisms mainly because it provide average values only. Therefore it has to be combined with surface science methods in order to reveal the interface structure and composition. Ex situ methods have been very useful over the latest....... Furthermore, it seems that detailed mathematical modeling using new tools like COMSOL is necessary for the synthesis of the large amount of data for a well-characterized electrode into one physical meaningful picture. A brief review of literature an own data will be presented with a practical example of SOFC...

"In situ preparation": new surgical procedure indicated for soft-tissue sarcoma of a lower limb in close proximity to major neurovascular structures.

Science.gov (United States)

Matsumoto, Seiichi; Kawaguchi, Noriyoshi; Manabe, Jun; Matsushita, Yasushi

2002-02-01

When soft-tissue sarcomas occur near neurovascular structures, preoperative images cannot always reveal the accurate relationship between the tumor and these structures. Therefore, in some patients, neurovascular structures are sacrificed unnecessarily. In other patients, neurovascular structures are preserved with an inappropriate margin, followed by local recurrence. The objective of this study was to evaluate a new surgical method, "in situ preparation" (ISP), which enables the preparation of neurovascular bundles and the intraoperative evaluation of the surgical margin without contamination by tumor cells. With this method, additional procedures, including pasteurization, alcohol soaking, and distilled water soaking of the preserved neurovascular bundle can also be performed to preserve the continuity of vessels. Between April 1992 and December 1998, 18 patients with soft-tissue sarcoma were operated on using ISP. The tumor and neurovascular structure were lifted en bloc from the surgical bed and separated from the field by the use of a vinyl sheet. The consistency of the neurovascular structures was preserved. The tissue block could be freely turned around and the neurovascular structure was separated from the block through the nearest approach. The margin between the tumor and neurovascular structure was evaluated, and an additional procedure, such as pasteurization, alcohol soaking or distilled water soaking, was performed, according to the safety of the surgical margin. Only one patient showed recurrence after ISP. Complications after ISP were arterial occlusion in two patients and nerve palsy in three patients. The main cause of these complications was the long period of pasteurization; modified additional procedures could prevent such complications. ISP is a useful method with which to ensure a safe surgical margin and good functional results.

Setup for in situ X-ray diffraction studies of thin film growth by magnetron sputtering

CERN Document Server

Ellmer, K; Weiss, V; Rossner, H

2001-01-01

A novel method is described for the in situ-investigation of nucleation and growth of thin films during magnetron sputtering. Energy dispersive X-ray diffraction with synchrotron light is used for the structural analysis during film growth. An in situ-magnetron sputtering chamber was constructed and installed at a synchrotron radiation beam line with a bending magnet. The white synchrotron light (1-70 keV) passes the sputtering chamber through Kapton windows and hits one of the substrates on a four-fold sample holder. The diffracted beam, observed under a fixed diffraction angle between 3 deg. and 10 deg., is energy analyzed by a high purity Ge-detector. The in situ-EDXRD setup is demonstrated for the growth of tin-doped indium oxide (ITO) films prepared by reactive magnetron sputtering from a metallic target.

Electrochemical studies, in-situ and ex-situ characterizations of different manganese compounds electrodeposited in aerated solutions; Etudes electrochimiques, suivis in-situ et caracterisations ex-situ de divers composes de manganese electrodeposes dans des solutions aerees

Energy Technology Data Exchange (ETDEWEB)

Peulon, S.; Lacroix, A.; Chausse, A. [Univ. d' Evry-val-d' Essonne, Laboratoire Analyse et Modelisation pour la Biologie et l' Environnement (LAMBE CNRS UMR 8587), 91 - Evry (France); Larabi-Gruet, N. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SECR/L3MR), 91 - Gif sur Yvette (France)

2007-07-01

This work deals with the electrodeposition of manganese compounds. A systematic study of the synthesis experimental conditions has been carried out, and the obtained depositions have been characterized by different ex-situ analyses methods (XRD, FTIR, SEM). The in-situ measurements of mass increase with a quartz microbalance during the syntheses have allowed to estimate the growth mechanisms which are in agreement with the ex-situ characterizations. The cation has an important role in the nature of the electrodeposited compounds. In presence of sodium, a mixed lamellar compound Mn(III)/Mn(IV), the birnessite, is deposited, whereas in presence of potassium, bixbyite is formed (Mn{sub 2}O{sub 3}), these two compounds having a main role in the environment. The substrate can also influence the nature of the formed intermediary compounds. Little studied compounds such as feitkneichtite ({beta}-MnOOH) and groutite ({alpha}-MnOOH) have been revealed. (O.M.)

Cluster tool for in situ processing and comprehensive characteriza tion of thin films at high temperatures.

Science.gov (United States)

Wenisch, Robert; Lungwitz, Frank; Hanf, Daniel; Heller, Rene; Zscharschuch, Jens; Hübner, René; von Borany, Johannes; Abrasonis, Gintautas; Gemming, Sibylle; Escobar-Galindo, Ramon; Krause, Matthias

2018-05-31

A new cluster tool for in situ real-time processing and depth-resolved compositional, structural and optical characterization of thin films at temperatures from -100 to 800 °C is described. The implemented techniques comprise magnetron sputtering, ion irradiation, Rutherford backscattering spectrometry, Raman spectroscopy and spectroscopic ellipsometry. The capability of the cluster tool is demonstrated for a layer stack MgO/ amorphous Si (~60 nm)/ Ag (~30 nm), deposited at room temperature and crystallized with partial layer exchange by heating up to 650°C. Its initial and final composition, stacking order and structure were monitored in situ in real time and a reaction progress was defined as a function of time and temperature.

Structural and Functional Imaging Studies in Chronic Cannabis Users: A Systematic Review of Adolescent and Adult Findings

Science.gov (United States)

Batalla, Albert; Bhattacharyya, Sagnik; Yücel, Murat; Fusar-Poli, Paolo; Crippa, Jose Alexandre; Nogué, Santiago; Torrens, Marta; Pujol, Jesús; Farré, Magí; Martin-Santos, Rocio

2013-01-01

Background The growing concern about cannabis use, the most commonly used illicit drug worldwide, has led to a significant increase in the number of human studies using neuroimaging techniques to determine the effect of cannabis on brain structure and function. We conducted a systematic review to assess the evidence of the impact of chronic cannabis use on brain structure and function in adults and adolescents. Methods Papers published until August 2012 were included from EMBASE, Medline, PubMed and LILACS databases following a comprehensive search strategy and pre-determined set of criteria for article selection. Only neuroimaging studies involving chronic cannabis users with a matched control group were considered. Results One hundred and forty-two studies were identified, of which 43 met the established criteria. Eight studies were in adolescent population. Neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum. These effects may be related to the amount of cannabis exposure. Functional neuroimaging studies suggest different patterns of resting global and brain activity during the performance of several cognitive tasks both in adolescents and adults, which may indicate compensatory effects in response to chronic cannabis exposure. Limitations However, the results pointed out methodological limitations of the work conducted to date and considerable heterogeneity in the findings. Conclusion Chronic cannabis use may alter brain structure and function in adult and adolescent population. Further studies should consider the use of convergent methodology, prospective large samples involving adolescent to adulthood subjects, and data-sharing initiatives. PMID:23390554

Structural and functional imaging studies in chronic cannabis users: a systematic review of adolescent and adult findings.

Directory of Open Access Journals (Sweden)

Albert Batalla

Full Text Available The growing concern about cannabis use, the most commonly used illicit drug worldwide, has led to a significant increase in the number of human studies using neuroimaging techniques to determine the effect of cannabis on brain structure and function. We conducted a systematic review to assess the evidence of the impact of chronic cannabis use on brain structure and function in adults and adolescents.Papers published until August 2012 were included from EMBASE, Medline, PubMed and LILACS databases following a comprehensive search strategy and pre-determined set of criteria for article selection. Only neuroimaging studies involving chronic cannabis users with a matched control group were considered.One hundred and forty-two studies were identified, of which 43 met the established criteria. Eight studies were in adolescent population. Neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum. These effects may be related to the amount of cannabis exposure. Functional neuroimaging studies suggest different patterns of resting global and brain activity during the performance of several cognitive tasks both in adolescents and adults, which may indicate compensatory effects in response to chronic cannabis exposure.However, the results pointed out methodological limitations of the work conducted to date and considerable heterogeneity in the findings.Chronic cannabis use may alter brain structure and function in adult and adolescent population. Further studies should consider the use of convergent methodology, prospective large samples involving adolescent to adulthood subjects, and data-sharing initiatives.

Progress on nuclear modifications of structure functions

Directory of Open Access Journals (Sweden)

Kumano S.

2016-01-01

Full Text Available We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrinooscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function b1 is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010’s.

In situ and operando transmission electron microscopy of catalytic materials

DEFF Research Database (Denmark)

Crozier, Peter A.; Hansen, Thomas Willum

2015-01-01

measurements of gas-phase catalytic products. To overcome this deficiency, operando TEM techniques are being developed that combine atomic characterization with the simultaneous measurement of catalytic products. This article provides a short review of the current status and major developments......) is a powerful technique for revealing the atomic structures of materials at elevated temperatures in the presence of reactive gases. This approach can allow the structure-reactivity relations underlying catalyst functionality to be investigated. Thus far, ETEM has been limited by the absence of in situ...... in the application of ETEM to gas-phase catalysis over the past 10 years....

Altered structure-function relations of semantic processing in youths with high-functioning autism: a combined diffusion and functional MRI study.

Science.gov (United States)

Lo, Yu-Chun; Chou, Tai-Li; Fan, Li-Ying; Gau, Susan Shur-Fen; Chiu, Yen-Nan; Tseng, Wen-Yih Isaac

2013-12-01

Deficits in language and communication are among the core symptoms of autism, a common neurodevelopmental disorder with long-term impairment. Despite the striking nature of the autistic language impairment, knowledge about its corresponding alterations in the brain is still evolving. We hypothesized that the dual stream language network is altered in autism, and that this alteration could be revealed by changes in the relationships between microstructural integrity and functional activation. The study recruited 20 right-handed male youths with autism and 20 carefully matched individually, typically developing (TD) youths. Microstructural integrity of the left dorsal and left ventral pathways responsible for language processing and the functional activation of the connected brain regions were investigated by using diffusion spectrum imaging and functional magnetic resonance imaging of a semantic task, respectively. Youths with autism had significantly poorer language function, and lower functional activation in left dorsal and left ventral regions of the language network, compared with TD youths. The TD group showed a significant correlation of the functional activation of the left dorsal region with microstructural integrity of the left ventral pathway, whereas the autism group showed a significant correlation of the functional activation of the left ventral region with microstructural integrity of the left dorsal pathway, and moreover verbal comprehension index was correlated with microstructural integrity of the left ventral pathway. These altered structure-function relationships in autism suggest possible involvement of the dual pathways in supporting deficient semantic processing. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.

Analysis of Lamellar Structures with Application of Generalized Functions

Directory of Open Access Journals (Sweden)

Kipiani Gela

2016-12-01

Full Text Available Theory of differential equations in respect of the functional area is based on the basic concepts on generalized functions and splines. There are some basic concepts related to the theory of generalized functions and their properties are considered in relation to the rod systems and lamellar structures. The application of generalized functions gives the possibility to effectively calculate step-variable stiffness lamellar structures. There are also widely applied structures, in that several in which a number of parallel load bearing layers are interconnected by discrete-elastic links. For analysis of system under study, such as design diagrams, there are applied discrete and discrete-continual models.

First in situ plasma and neutral gas measurements at comet Halley: initial VEGA results

International Nuclear Information System (INIS)

Gringauz, K.I.; Remizov, A.P.; Gombosi, T.I.

1986-04-01

The first in situ observations and a description of the large scale behaviour of comet Halley's plasma environment are presented. The scientific objectives of the PLASMAG-1 experiment were as follows: to study the change of plasma parameters and distributions as a function of cometocentric distance; to investigate the existence and structure of the cometary bow shock; to determine the change in chemical composition of the heavily mass loaded plasma as the spacecraft approached the comet; and to measure the neutral gas distribution along the spacecraft trajectory. (author)

Brain function and structure and risk for incident diabetes: The Atherosclerosis Risk in Communities Study.

Science.gov (United States)

Bancks, Michael P; Alonso, Alvaro; Gottesman, Rebecca F; Mosley, Thomas H; Selvin, Elizabeth; Pankow, James S

2017-12-01

Diabetes is prospectively associated with cognitive decline. Whether lower cognitive function and worse brain structure are prospectively associated with incident diabetes is unclear. We analyzed data for 10,133 individuals with cognitive function testing (1990-1992) and 1212 individuals with brain magnetic resonance imaging (1993-1994) from the Atherosclerosis Risk in Communities cohort. We estimated hazard ratios for incident diabetes through 2014 after adjustment for traditional diabetes risk factors and cohort attrition. Higher level of baseline cognitive function was associated with lower risk for diabetes (per 1 standard deviation, hazard ratio = 0.94; 95% confidence interval = 0.90, 0.98). This association did not persist after accounting for baseline glucose level, case ascertainment methods, and cohort attrition. No association was observed between any brain magnetic resonance imaging measure and incident diabetes. This is one of the first studies to prospectively evaluate the association between both cognitive function and brain structure and the incidence of diabetes. Copyright © 2017 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Electron microscopic in situ study of phase and defect formation in Bi2Sr2CaCu2Oy single crystals in heating

International Nuclear Information System (INIS)

Goncharov, V.A.; Ignat'eva, E.Yu.; Osip'yan, Yu.A.; Suvorov, Eh.V.

1997-01-01

The nonthermal effect of electron irradiation on generating of new phases and structural defects has been uncovered during the investigation of structural variations of monocrystals Bi 2 Sr 2 CaCu 2 O y on heating in situ. The stability of the modulated structure and the package defects to heating under the electron beam action and in the absence of the irradiation has been studied

Proton structure functions at small x

International Nuclear Information System (INIS)

Hentschinski, Martin

2015-01-01

Proton structure functions are measured in electron-proton collision through inelastic scattering of virtual photons with virtuality Q on protons; x denotes the momentum fraction carried by the struck parton. Proton structure functions are currently described with excellent accuracy in terms of scale dependent parton distribution functions, defined in terms of collinear factorization and DGLAP evolution in Q. With decreasing x however, parton densities increase and are ultimately expected to saturate. In this regime DGLAP evolution will finally break down and non-linear evolution equations w.r.t x are expected to take over. In the first part of the talk we present recent result on an implementation of physical DGLAP evolution. Unlike the conventional description in terms of parton distribution functions, the former describes directly the Q dependence of the measured structure functions. It is therefore physical insensitive to factorization scheme and scale ambiguities. It therefore provides a more stringent test of DGLAP evolution and eases the manifestation of (non-linear) small x effects. It however requires a precise measurement of both structure functions F 2 and F L , which will be only possible at future facilities, such as an Electron Ion Collider. In the second part we present a recent analysis of the small x region of the combined HERA data on the structure function F 2 . We demonstrate that (linear) next-to-leading order BFKL evolution describes the effective Pomeron intercept, determined from the combined HERA data, once a resummation of collinear enhanced terms is included and the renormalization scale is fixed using the BLM optimal scale setting procedure. We also provide a detailed description of the Q and x dependence of the full structure functions F 2 in the small x region, as measured at HERA. Predictions for the structure function F L are found to be in agreement with the existing HERA data. (paper)

Structure, dynamics, and function of the monooxygenase P450 BM-3: insights from computer simulations studies

International Nuclear Information System (INIS)

Roccatano, Danilo

2015-01-01

The monooxygenase P450 BM-3 is a NADPH-dependent fatty acid hydroxylase enzyme isolated from soil bacterium Bacillus megaterium. As a pivotal member of cytochrome P450 superfamily, it has been intensely studied for the comprehension of structure–dynamics–function relationships in this class of enzymes. In addition, due to its peculiar properties, it is also a promising enzyme for biochemical and biomedical applications. However, despite the efforts, the full understanding of the enzyme structure and dynamics is not yet achieved. Computational studies, particularly molecular dynamics (MD) simulations, have importantly contributed to this endeavor by providing new insights at an atomic level regarding the correlations between structure, dynamics, and function of the protein. This topical review summarizes computational studies based on MD simulations of the cytochrome P450 BM-3 and gives an outlook on future directions. (topical review)

Monte Carlo study of four-spinon dynamic structure function in antiferromagnetic Heisenberg model

International Nuclear Information System (INIS)

Si-Lakhal, B.; Abada, A.

2003-11-01

Using Monte Carlo integration methods, we describe the behavior of the exact four-s pinon dynamic structure function S 4 in the antiferromagnetic spin 1/2 Heisenberg quantum spin chain as a function of the neutron energy ω and momentum transfer k. We also determine the fourspinon continuum, the extent of the region in the (k, ω) plane outside which S 4 is identically zero. In each case, the behavior of S 4 is shown to be consistent with the four-spinon continuum and compared to the one of the exact two-spinon dynamic structure function S 2 . Overall shape similarity is noted. (author)

Triplex in-situ hybridization

Science.gov (United States)

Fresco, Jacques R.; Johnson, Marion D.

2002-01-01

Disclosed are methods for detecting in situ the presence of a target sequence in a substantially double-stranded nucleic acid segment, which comprises: a) contacting in situ under conditions suitable for hybridization a substantially double-stranded nucleic acid segment with a detectable third strand, said third strand being capable of hybridizing to at least a portion of the target sequence to form a triple-stranded structure, if said target sequence is present; and b) detecting whether hybridization between the third strand and the target sequence has occured.

Photon structure functions at small x in holographic QCD

International Nuclear Information System (INIS)

Watanabe, Akira; Li, Hsiang-nan

2015-01-01

We investigate the photon structure functions at small Bjorken variable x in the framework of the holographic QCD, assuming dominance of the Pomeron exchange. The quasi-real photon structure functions are expressed as convolution of the Brower–Polchinski–Strassler–Tan (BPST) Pomeron kernel and the known wave functions of the U(1) vector field in the five-dimensional AdS space, in which the involved parameters in the BPST kernel have been fixed in previous studies of the nucleon structure functions. The predicted photon structure functions, as confronted with data, provide a clean test of the BPST kernel. The agreement between theoretical predictions and data is demonstrated, which supports applications of holographic QCD to hadronic processes in the nonperturbative region. Our results are also consistent with those derived from the parton distribution functions of the photon proposed by Glück, Reya, and Schienbein, implying realization of the vector meson dominance in the present model setup.

Nanoindentation studies of ex situ AlN/Al metal matrix nanocomposites

International Nuclear Information System (INIS)

Fale, Sandeep; Likhite, Ajay; Bhatt, Jatin

2014-01-01

Highlights: • Formation of in-situ phases nucleated on AlN particles strengthens the matrix. • Formation of in-situ phases increases with AlN content in nanocomposites. • Stronger in-situ phases results in increased hardness and modulus of elasticity. - Abstract: Nanocrystalline Aluminium nitride (AlN) powder is dispersed in different weight ratio in Aluminum matrix to fabricate metal matrix nanocomposite (MMNC) using ex situ melt metallurgy process. The synthesized Al–AlN nanocomposites are studied for phase analysis using high resolution scanning electron microscopy (FEG-SEM) and for hardness behavior using microindentation and nanoindentation tests. Quantitative analysis of the oxide phases is calculated from thermodynamic data and mass balance equation using elemental data obtained from energy dispersive spectroscopy (EDS) results. Role of oxide phases in association with AlN particles is investigated to understand the mechanical behavior of composites using nanoindentation tester. Load–displacement profile obtained from nanoindentation test reveals distribution of oxide phases along with AlN particle and their effect on indent penetration

In Situ Raman Study of Liquid Water at High Pressure.

Science.gov (United States)

Romanenko, Alexandr V; Rashchenko, Sergey V; Goryainov, Sergey V; Likhacheva, Anna Yu; Korsakov, Andrey V

2018-06-01

A pressure shift of Raman band of liquid water (H 2 O) may be an important tool for measuring residual pressures in mineral inclusions, in situ barometry in high-pressure cells, and as an indicator of pressure-induced structural transitions in H 2 O. However, there was no consensus as to how the broad and asymmetric water Raman band should be quantitatively described, which has led to fundamental inconsistencies between reported data. In order to overcome this issue, we measured Raman spectra of H 2 O in situ up to 1.2 GPa using a diamond anvil cell, and use them to test different approaches proposed for the description of the water Raman band. We found that the most physically meaningful description of water Raman band is the decomposition into a linear background and three Gaussian components, associated with differently H-bonded H 2 O molecules. Two of these components demonstrate a pronounced anomaly in pressure shift near 0.4 GPa, supporting ideas of structural transition in H 2 O at this pressure. The most convenient approach for pressure calibration is the use of "a linear background + one Gaussian" decomposition (the pressure can be measured using the formula P (GPa) = -0.0317(3)·Δν G (cm -1 ), where Δν G represents the difference between the position of water Raman band, fitted as a single Gaussian, in measured spectrum and spectrum at ambient pressure).

Diquarks and nucleon structure functions

International Nuclear Information System (INIS)

Linkevich, A.D.; Savrin, V.I.; Skachkov, N.B.

1982-01-01

Formulae for structure functions of the deep-inelastic lepton-nucleon scattering are obtained through relativistic wave functions of systems composed of particles with spins 0, 1/2 and 1, 1/2. These wave functions are solutions of covariant two-particle single-time equations describing the nucleon as a system formed out of a quark and a diquark. Diquark is considered as a boson with the spin 0 and 1. The expressions for the nucleon structure functions are obtained by using the matrix elements of the current operator corresponding to the elastic scattering of the photon on a quark and on a diquark [ru

Design of an electrochemical cell for in situ XAS studies

Energy Technology Data Exchange (ETDEWEB)

Watanabe, N. [Instituto de Quimica, Universidade Estadual de Campinas (UNICAMP), Box 6154, CEP 13083-970, Campinas, SP (Brazil); Morais, J. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15051, CEP 91501-970, Porto Alegre, RS (Brazil); Alves, M.C.M. [Instituto de Quimica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15003, CEP 91501-970, Porto Alegre, RS (Brazil)], E-mail: maria@iq.ufrgs.br

2007-05-15

In situ X-ray absorption spectroscopy (XAS) studies have been carried out on the electrochemical insertion of Co metal particles in polypyrrole. This has become possible due to the development of an electrochemical cell to allow XAS studies in fluorescence geometry under steady-state conditions. The experimental set-up allows the in situ monitoring of the structural and electronic changes of the selected atom in a matrix. The project of the electrochemical cell is presented with the results obtained at different stages of the electrochemical process. XANES and EXAFS results showed that the initial stage of the cobalt insertion in polypyrrole took place in an ionic form, like [-[(C{sub 4}H{sub 2}N){sub 3}CH{sub 3}(CH{sub 2}){sub 11}OSO{sub 3}{sup -}]{sub 6}Co{sup 2+}] with posterior reduction to a metallic form. The quantitative analysis of the first shell shows that, at -0.60 V, the cobalt atoms are surrounded by 6 ({+-}0.5) atoms located at 2.12 ({+-}0.05) A with a large Debye-Waller factor ({sigma}{sup 2}) value of 0.0368 ({+-}0.0074). At -0.80 V, two distances of R = 1.99 ({+-}0.01) and R = 2.50 ({+-}0.01) A show the coexistence of cobalt in the oxidized and reduced (Co{sup 0}) forms. The Co-Co distance corresponds to that of bulk cobalt. At -1.20 V, the obtained values of N = 12 ({+-}0.5) and R = 2.56 ({+-}0.01) A and a Debye-Waller factor of 0.0176 ({+-}0.0004) suggest the formation of metallic cobalt in a quite disordered form.

Relationships between structure and function: System structure matters whether you are in a wetland or a college classroom

Science.gov (United States)

Andrews, Sarah Elizabeth

Part I of this dissertation describes two research projects I undertook to understand how structure influences function in freshwater wetlands. In the first study I tested the hypothesis that wetland structure (created versus natural) would influence function (methane cycling). Created wetlands had reduced rates of potential methane production and potential methane oxidation compared to natural wetlands; this was most likely explained by differences in edaphic factors that characterized each wetland, particularly soil moisture and soil organic matter. In the second study (Andrews et al. 2013), I tested the hypothesis that plant community structure (functional group composition, richness, presence/absence) would influence function (methane and iron cycling) in wetland mesocosms. Plant functional group richness was less important than the type of vegetation present: the presence of perennial vegetation (reeds or tussocks) led to increased rates of potential iron reduction compared to when only annual vegetation was present. Part II of this dissertation describes research I undertook to understand how structure influences function in an undergraduate soil science course. In the first study I tested the hypothesis that course structure (traditional versus studio) would influence function (student performance) in the course. Students in the studio course outperformed students in the traditional course; there was also a decrease in the fail rate. In the second study I looked at students' perspectives on their learning and experiences (function) in the studio course and asked whether students' epistemological development influenced this function. Interviews with students revealed that active learning, the integrated nature of the course, community, and variety of learning and assessment methods helped student learning. Students' epistemological development (interpreted from the Measure of Epistemological Reflection) permeated much of what they spoke about during the

Summary of feasibility studies on in situ disposal as a decommissioning option for nuclear facilities

International Nuclear Information System (INIS)

Helbrecht, R.A.

2002-01-01

A scoping study was conducted over the period 1998-2000 to consider the feasibility of in situ disposal as a decommissioning option for AECL's Nuclear Power Demonstration Reactor located at Rolphton, Ontario. The results of a detailed assessment are summarized and the study concludes that in situ disposal appears feasible. Additional work required to confirm the results is also identified. A second in situ component, contaminated Winnipeg River sediments at AECL's Whiteshell Laboratory located in Manitoba, was also evaluated. That study concluded that in situ abandonment would have no adverse impact on aquatic life, humans and the environment. A summary of the study is presented as an appendix to the report. (author)

Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

International Nuclear Information System (INIS)

Bindi, Luca

2009-01-01

The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: α a = 1.5 x 10 -5 K -1 , α b = 3.0 x 10 -5 K -1 , α c = 2.2 x 10 -5 K -1 , and the bulk thermal expansion coefficient α V is 5.4 x 10 -5 K -1 for the temperature range 298-463 K

Bio-functions and molecular carbohydrate structure association study in forage with different source origins revealed using non-destructive vibrational molecular spectroscopy techniques.

Science.gov (United States)

Ji, Cuiying; Zhang, Xuewei; Yan, Xiaogang; Mostafizar Rahman, M; Prates, Luciana L; Yu, Peiqiang

2017-08-05

The objectives of this study were to: 1) investigate forage carbohydrate molecular structure profiles; 2) bio-functions in terms of CHO rumen degradation characteristics and hourly effective degradation ratio of N to OM (HED N/OM ), and 3) quantify interactive association between molecular structures, bio-functions and nutrient availability. The vibrational molecular spectroscopy was applied to investigate the structure feature on a molecular basis. Two sourced-origin alfalfa forages were used as modeled forages. The results showed that the carbohydrate molecular structure profiles were highly linked to the bio-functions in terms of rumen degradation characteristics and hourly effective degradation ratio. The molecular spectroscopic technique can be used to detect forage carbohydrate structure features on a molecular basis and can be used to study interactive association between forage molecular structure and bio-functions. Copyright © 2017 Elsevier B.V. All rights reserved.

Coral Reef Color: Remote and In-Situ Imaging Spectroscopy of Reef Structure and Function

Science.gov (United States)

Hochberg, E. J.

2016-02-01

Coral reefs are threatened at local to global scales by a litany of anthropogenic impacts, including overfishing, coastal development, marine and watershed pollution, rising ocean temperatures, and ocean acidification. However, available data for the primary indicator of coral reef condition — proportional cover of living coral — are surprisingly sparse and show patterns that contradict the prevailing understanding of how environment impacts reef condition. Remote sensing is the only available tool for acquiring synoptic, uniform data on reef condition at regional to global scales. Discrimination between coral and other reef benthos relies on narrow wavebands afforded by imaging spectroscopy. The same spectral information allows non-invasive quantification of photosynthetic pigment composition, which shows unexpected phenological trends. There is also potential to link biodiversity with optical diversity, though there has been no effort in that direction. Imaging spectroscopy underlies the light-use efficiency model for reef primary production by quantifying light capture, which in turn indicates biochemical capacity for CO2 assimilation. Reef calcification is strongly correlated with primary production, suggesting the possibility for an optics-based model of that aspect of reef function, as well. By scaling these spectral models for use with remote sensing, we can vastly improve our understanding of reef structure, function, and overall condition across regional to global scales. By analyzing those remote sensing products against ancillary environmental data, we can construct secondary models to predict reef futures in the era of global change. This final point is the objective of CORAL (COral Reef Airborne Laboratory), a three-year project funded under NASA's Earth Venture Suborbital-2 program to investigate the relationship between coral reef condition at the ecosystem scale and various nominal biogeophysical forcing parameters.

Altered Structural and Functional Connectivity of Juvenile Myoclonic Epilepsy: An fMRI Study

Directory of Open Access Journals (Sweden)

Chengqing Zhong

2018-01-01

Full Text Available The aim of this study was to investigate the structural and functional connectivity (FC of juvenile myoclonic epilepsy (JME using resting state functional magnetic resonance imaging (rs-fMRI. High-resolution T1-weighted magnetic resonance imaging (MRI and rs-fMRI data were collected in 25 patients with JME and in 24 control subjects. A FC analysis was subsequently performed, with seeding at the regions that demonstrated between-group differences in gray matter volume (GMV. Then, the observed structural and FCs were associated with the clinical manifestations. The decreased GMV regions were found in the bilateral anterior cerebellum, the right orbital superior frontal gyrus, the left middle temporal gyrus, the left putamen, the right hippocampus, the bilateral caudate, and the right thalamus. The changed FCs were mainly observed in the motor-related areas and the cognitive-related areas. The significant findings of this study revealed an important role for the cerebellum in motor control and cognitive regulation in JME patients, which also have an effect on the activity of the occipital lobe. In addition, the changed FCs were related to the clinical features of JME patients. The current observations may contribute to the understanding of the pathogenesis of JME.

The virtual photon structure functions and AdS/QCD correspondence

International Nuclear Information System (INIS)

Yoshida, Yutaka

2010-01-01

We study the virtual photons structure functions from gauge/string duality. If the Bjorken variable x is not small, supergravity approximation becomes good in dual string theory. We calculate the virtual photon structure functions at large 't Hooft coupling in a moderate x-region and determine x-behavior of the structure functions. We also show that the Callan-Gross relation F L =0 is satisfied to a good approximation in gravity calculation. (author)

In situ transmission electron microscopy studies of microstructure evolution in Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 piezoceramic

International Nuclear Information System (INIS)

Zakhozheva, Marina

2016-01-01

The purpose of this work is to understand the microstructural features which contribute to the strong electromechanical properties of the lead-free Ba (Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 (BZT-xBCT) piezoelectric ceramic. Detailed conventional transmission electron microscopy (TEM) studies on a broad variety of BZT - xBCT were performed in order to demonstrate the composition dependent structural changes. Moreover, several in situ TEM techniques, including in situ hot- and cold-stage, in situ electric field and in situ electric field with simultaneous cooling, were successfully applied in order to monitor the domain morphology evolution in real time. By means of in situ temperature dependent TEM experiments it was shown that during rhombohedral → orthorhombic → tetragonal phase transition the domain morphology changed according to the crystal structure present. During in situ electric field investigations the displacement of the domain walls and changes in the domain configuration during electrical poling were observed, which indicates a high extrinsic contribution to the piezoelectric response in all BZT - xBCT compositions studied. From the results of in situ electric field TEM experiments with simultaneous cooling, we obtained experimental evidence that the further the composition deviates from the polymorphic phase boundary, the higher the electric field required to fully pole the material.

Conflict between object structural and functional affordances in peripersonal space.

Science.gov (United States)

Kalénine, Solène; Wamain, Yannick; Decroix, Jérémy; Coello, Yann

2016-10-01

Recent studies indicate that competition between conflicting action representations slows down planning of object-directed actions. The present study aims to assess whether similar conflict effects exist during manipulable object perception. Twenty-six young adults performed reach-to-grasp and semantic judgements on conflictual objects (with competing structural and functional gestures) and non-conflictual objects (with similar structural and functional gestures) presented at difference distances in a 3D virtual environment. Results highlight a space-dependent conflict between structural and functional affordances. Perceptual judgments on conflictual objects were slower that perceptual judgments on non-conflictual objects, but only when objects were presented within reach. Findings demonstrate that competition between structural and functional affordances during object perception induces a processing cost, and further show that object position in space can bias affordance competition. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of silica particles modified by in-situ and ex-situ methods on the reinforcement of silicone rubber

International Nuclear Information System (INIS)

Song, Yingze; Yu, Jinhong; Dai, Dan; Song, Lixian; Jiang, Nan

2014-01-01

Highlights: • In-situ and ex-situ methods were applied to modify silica particles. • In-situ method was more beneficial to preparing silica particles with high BET surface area. • Silicone rubber filled with in-situ modified silica exhibits excellent mechanical and thermal properties. - Abstract: In-situ and ex-situ methods were applied to modify silica particles in order to investigate their effects on the reinforcement of silicone rubber. Surface area and pore analyzer, laser particle size analyzer, Fourier-transform infrared spectroscopy (FTIR), contact-angle instrument, and transmission electron microscope (TEM) were utilized to investigate the structure and properties of the modified silica particles. Dynamic mechanical thermal analyzer (DMTA) was employed to characterize the vulcanizing behavior and mechanical properties of the composites. Thermogravimetric analysis (TGA) was performed to test the thermal stability of the composites. FTIR and contact angle analysis indicated that silica particles were successfully modified by these two methods. The BET surface area and TEM results reflected that in-situ modification was more beneficial to preparing silica particles with irregular shape and higher BET surface area in comparison with ex-situ modification. The DMTA and TGA data revealed that compared with ex-situ modification, the in-situ modification produced positive influence on the reinforcement of silicone rubber

Population structure analysis using rare and common functional variants

Directory of Open Access Journals (Sweden)

Ding Lili

2011-11-01

Full Text Available Abstract Next-generation sequencing technologies now make it possible to genotype and measure hundreds of thousands of rare genetic variations in individuals across the genome. Characterization of high-density genetic variation facilitates control of population genetic structure on a finer scale before large-scale genotyping in disease genetics studies. Population structure is a well-known, prevalent, and important factor in common variant genetic studies, but its relevance in rare variants is unclear. We perform an extensive population structure analysis using common and rare functional variants from the Genetic Analysis Workshop 17 mini-exome sequence. The analysis based on common functional variants required 388 principal components to account for 90% of the variation in population structure. However, an analysis based on rare variants required 532 significant principal components to account for similar levels of variation. Using rare variants, we detected fine-scale substructure beyond the population structure identified using common functional variants. Our results show that the level of population structure embedded in rare variant data is different from the level embedded in common variant data and that correcting for population structure is only as good as the level one wishes to correct.

Sulfur X-Ray Absorption Spectroscopy of Living Mammalian Cells: An Enabling Tool for Sulfur Metabolomics. in Situ Observation of Uptake of Taurine Into MDCK Cells

Energy Technology Data Exchange (ETDEWEB)

Gnida, M.; Sneeden, E.Yu; Whitin, J.C.; Prince, R.C.; Pickering, I.J.; Korbas, M.; George, G.N.

2009-06-01

Sulfur is essential for life, with important roles in biological structure and function. However, because of a lack of suitable biophysical techniques, in situ information about sulfur biochemistry is generally difficult to obtain. Here, we present an in situ sulfur X-ray absorption spectroscopy (S-XAS) study of living cell cultures of the mammalian renal epithelial MDCK cell line. A great deal of information is retrieved from a characteristic sulfonate feature in the X-ray absorption spectrum of the cell cultures, which can be related to the amino acid taurine. We followed the time and dose dependence of uptake of taurine into MDCK cell monolayers. The corresponding uptake curves showed a typical saturation behavior with considerable levels of taurine accumulation inside the cells (as much as 40% of total cellular sulfur). We also investigated the polarity of uptake of taurine into MDCK cells, and our results confirmed that uptake in situ is predominantly a function of the basolateral cell surface.

Cardiac structure and function in Cushing's syndrome: a cardiac magnetic resonance imaging study.

Science.gov (United States)

Kamenický, Peter; Redheuil, Alban; Roux, Charles; Salenave, Sylvie; Kachenoura, Nadjia; Raissouni, Zainab; Macron, Laurent; Guignat, Laurence; Jublanc, Christel; Azarine, Arshid; Brailly, Sylvie; Young, Jacques; Mousseaux, Elie; Chanson, Philippe

2014-11-01

Patients with Cushing's syndrome have left ventricular (LV) hypertrophy and dysfunction on echocardiography, but echo-based measurements may have limited accuracy in obese patients. No data are available on right ventricular (RV) and left atrial (LA) size and function in these patients. The objective of the study was to evaluate LV, RV, and LA structure and function in patients with Cushing's syndrome by means of cardiac magnetic resonance, currently the reference modality in assessment of cardiac geometry and function. Eighteen patients with active Cushing's syndrome and 18 volunteers matched for age, sex, and body mass index were studied by cardiac magnetic resonance. The imaging was repeated in the patients 6 months (range 2-12 mo) after the treatment of hypercortisolism. Compared with controls, patients with Cushing's syndrome had lower LV, RV, and LA ejection fractions (P Cushing's syndrome is associated with subclinical biventricular and LA systolic dysfunctions that are reversible after treatment. Despite skeletal muscle atrophy, Cushing's syndrome patients have an increased LV mass, reversible upon correction of hypercortisolism.

In situ KPFM imaging of local photovoltaic characteristics of structured organic photovoltaic devices.

Science.gov (United States)

Watanabe, Satoshi; Fukuchi, Yasumasa; Fukasawa, Masako; Sassa, Takafumi; Kimoto, Atsushi; Tajima, Yusuke; Uchiyama, Masanobu; Yamashita, Takashi; Matsumoto, Mutsuyoshi; Aoyama, Tetsuya

2014-02-12

Here, we discuss the local photovoltaic characteristics of a structured bulk heterojunction, organic photovoltaic devices fabricated with a liquid carbazole, and a fullerene derivative based on analysis by scanning kelvin probe force microscopy (KPFM). Periodic photopolymerization induced by an interference pattern from two laser beams formed surface relief gratings (SRG) in the structured films. The surface potential distribution in the SRGs indicates the formation of donor and acceptor spatial distribution. Under illumination, the surface potential reversibly changed because of the generation of fullerene anions and hole transport from the films to substrates, which indicates that we successfully imaged the local photovoltaic characteristics of the structured photovoltaic devices. Using atomic force microscopy, we confirmed the formation of the SRG because of the material migration to the photopolymerized region of the films, which was induced by light exposure through photomasks. The structuring technique allows for the direct fabrication and the control of donor and acceptor spatial distribution in organic photonic and electronic devices with minimized material consumption. This in situ KPFM technique is indispensable to the fabrication of nanoscale electron donor and electron acceptor spatial distribution in the devices.

Network-level structure-function relationships in human neocortex

NARCIS (Netherlands)

Miŝic, Bratislav; Betzel, Richard F.; De Reus, Marcel A.; Van Den Heuvel, Martijn P.; Berman, Marc G.; McIntosh, Anthony R.; Sporns, Olaf

2016-01-01

The dynamics of spontaneous fluctuations in neural activity are shaped by underlying patterns of anatomical connectivity. While numerous studies have demonstrated edge-wise correspondence between structural and functional connections, much less is known about how large-scale coherent functional

Impaired testicular function in patients with carcinoma-in-situ of the testis

DEFF Research Database (Denmark)

Petersen, P M; Giwercman, A; Hansen, S W

1999-01-01

for testicular cancer. Biopsy of the contralateral testis had showed CIS in a group of 24 patients and no evidence of CIS in the other group of 30 patients. Semen quality and serum levels of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were compared in these two groups of men...... after orchidectomy but before further treatment for testicular cancer. RESULTS: Significantly higher LH levels (median, 8.1 IU/L v 4.8 IU/L; P ...PURPOSE: To elucidate the biologic association between germ cell neoplasia and testicular dysfunction, through investigation of Leydig cell function and semen quality in men with carcinoma-in-situ (CIS) of the testis. PATIENTS AND METHODS: We examined two groups of men, unilaterally orchidectomized...

In situ dehydration of yugawaralite

DEFF Research Database (Denmark)

Artioli, G.; Ståhl, Kenny; Cruciani, G.

2001-01-01

The structural response of the natural zeolite yugawaralite (CaAl2Si6O16. 4H(2)O) upon thermally induced dehydration has been studied by Rietveld analysis of temperature-resolved powder diffraction data collected in situ in the temperature range 315-791 K using synchrotron radiation. The room...... progressively disappearing as the dehydration proceeds. The yugawaralite structure reacts to the release of water molecules with small changes in the Ca-O bond distances and minor distortions of the tetrahedral framework up to about 695 K. Above this temperature the Ca coordination falls below 7 (four framework...

Crystal Structure Studies of Human Dental Apatite as a Function of Age

Directory of Open Access Journals (Sweden)

Th. Leventouri

2009-01-01

Full Text Available Studies of the average crystal structure properties of human dental apatite as a function of age in the range of 5–87 years are reported. The crystallinity of the dental hydroxyapatite decreases with the age. The a-lattice constant that is associated with the carbonate content in carbonate apatite decreases with age in a systematic way, whereas the c-lattice constant does not change significantly. Thermogravimetric measurements demonstrate an increase of the carbonate content with the age. FTIR spectroscopy reveals both B and A-type carbonate substitutions with the B-type greater than the A-type substitution by a factor up to ~5. An increase of the carbonate content as a function of age can be deduced from the ratio of the 2CO3 to the 1PO4 IR modes.

Structural and functional studies on human coagulation factor V

OpenAIRE

Neut Kolfschoten, Marijn van der

2005-01-01

The aim of this research was to obtain a better insight into the structure and functioning of clotting factor V (FV), a protein that plays an important role in the regulation of clotting. Congenital defects in FV can greatly disturb the coagulation system, and can lead to symptoms ranging from para-haemophilia to thrombosis. One example of a congenital defect in FV I is the R506Q mutation (an aminoacid change at position 506 in the aminoacid chain of FV). This deviating FV molecule (also know...

Influence of van der Waals forces on the adsorption structure of benzene on silicon studied using density functional theory

DEFF Research Database (Denmark)

Johnston, Karen; Kleis, Jesper; Lundqvist, Bengt

2008-01-01

Two different adsorption configurations of benzene on the Si(001)-(2×1) surface, the tight-bridge and butterfly structures, were studied using density functional theory. Several exchange and correlation functionals were used, including the recently developed van der Waals density functional (vd...

Altered resting brain function and structure in professional badminton players.

Science.gov (United States)

Di, Xin; Zhu, Senhua; Jin, Hua; Wang, Pin; Ye, Zhuoer; Zhou, Ke; Zhuo, Yan; Rao, Hengyi

2012-01-01

Neuroimaging studies of professional athletic or musical training have demonstrated considerable practice-dependent plasticity in various brain structures, which may reflect distinct training demands. In the present study, structural and functional brain alterations were examined in professional badminton players and compared with healthy controls using magnetic resonance imaging (MRI) and resting-state functional MRI. Gray matter concentration (GMC) was assessed using voxel-based morphometry (VBM), and resting-brain functions were measured by amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity. Results showed that the athlete group had greater GMC and ALFF in the right and medial cerebellar regions, respectively. The athlete group also demonstrated smaller ALFF in the left superior parietal lobule and altered functional connectivity between the left superior parietal and frontal regions. These findings indicate that badminton expertise is associated with not only plastic structural changes in terms of enlarged gray matter density in the cerebellum, but also functional alterations in fronto-parietal connectivity. Such structural and functional alterations may reflect specific experiences of badminton training and practice, including high-capacity visuo-spatial processing and hand-eye coordination in addition to refined motor skills.

In-Situ TEM Study of a Nanoporous Ni–Co Catalyst Used for the Dry Reforming of Methane

Directory of Open Access Journals (Sweden)

Takeshi Fujita

2017-10-01

Full Text Available We performed in-situ transmission electron microscopy (TEM on a dealloyed nanoporous NiCo catalyst used for the dry reforming of methane (DRM to investigate the origin of the catalytic activity and structural durability. The in-situ observations and local chemical analysis indicated that the DRM induced chemical demixing of Ni and Co accompanied by grain refinement, implying possible “synergic effects” in a general bimetallic NiCo catalyst when used for the DRM.

Structure functions and correlations in nuclei

International Nuclear Information System (INIS)

Fantoni, S.

1988-01-01

In this paper the results obtained for the static structure function S(k) and the longitudinal structure function S L (k) of 3 H, 3 He and 4 He nuclei and nuclear matter are presented and discussed. The calculations have been performed using realistic wave functions obtained from Faddeev and variational theories. The Monte Carlo method has been used to calculate the structure functions of finite systems, and the FHNC/SOC method for nuclear matter. The results for the 3 He nucleus are in agreement with the recent Saclay data. The results for nuclear matter are compared with the experimental data relative to heavier nuclei, like e.g. 40 Ca

Functional annotation by sequence-weighted structure alignments: statistical analysis and case studies from the Protein 3000 structural genomics project in Japan.

Science.gov (United States)

Standley, Daron M; Toh, Hiroyuki; Nakamura, Haruki

2008-09-01

A method to functionally annotate structural genomics targets, based on a novel structural alignment scoring function, is proposed. In the proposed score, position-specific scoring matrices are used to weight structurally aligned residue pairs to highlight evolutionarily conserved motifs. The functional form of the score is first optimized for discriminating domains belonging to the same Pfam family from domains belonging to different families but the same CATH or SCOP superfamily. In the optimization stage, we consider four standard weighting functions as well as our own, the "maximum substitution probability," and combinations of these functions. The optimized score achieves an area of 0.87 under the receiver-operating characteristic curve with respect to identifying Pfam families within a sequence-unique benchmark set of domain pairs. Confidence measures are then derived from the benchmark distribution of true-positive scores. The alignment method is next applied to the task of functionally annotating 230 query proteins released to the public as part of the Protein 3000 structural genomics project in Japan. Of these queries, 78 were found to align to templates with the same Pfam family as the query or had sequence identities > or = 30%. Another 49 queries were found to match more distantly related templates. Within this group, the template predicted by our method to be the closest functional relative was often not the most structurally similar. Several nontrivial cases are discussed in detail. Finally, 103 queries matched templates at the fold level, but not the family or superfamily level, and remain functionally uncharacterized. 2008 Wiley-Liss, Inc.

H electro-insertion into Pd/Pt(1 1 1) nanofilms: an original method for isotherm measurement coupled to in situ surface X-ray diffraction structural study

International Nuclear Information System (INIS)

Soldo-Olivier, Y.; Sibert, E.; Previdello, B.; Lafouresse, M.C.; Maillard, F.; De Santis, M.

2013-01-01

In order to get a thorough comprehension of the mechanisms governing hydrogen insertion into nanometric metallic films, we have studied ultra-thin Pd/Pt(1 1 1) layers. In this paper we propose an original method allowing the measurement of hydrogen insertion electrochemical isotherms. The use of a hanging meniscus rotating disc electrode and a new calculation approach permit to remove the contributions to the insertion charge of both hydrogen evolution and hydrogen oxidation reactions. Indeed, compared to hydrogen insertion such terms become non-negligible in the case of nanometric deposits, due to their large surface/bulk atom ratio. We have measured hydrogen insertion isotherms for Pd/Pt(1 1 1) films from 14 ML down to 4 ML. Independently from the film thickness, the maximum hydrogen insertion rate (H/Pd) max is smaller than that of bulk Pd. The so-called two-phase region is still present, but contrarily to bulk Pd it is characterized by a slope. Both hydrogen solubility and the two-phase domain width diminish with the decrease of the film thickness. In the present work the behaviour of hydrogen electrochemical insertion isotherms is interpreted in the light of the Pd nanofilms structure obtained with in situ surface X-ray diffraction. The lattice constraints induced by the substrate result in a lower insertion rate in the Pd deposit close to the Pt–Pd interface. Only the outermost region of the film is relaxed and behaves like bulk Pd. This description quantitatively accounts for the experimental behaviour of (H/Pd) max as a function of the film thickness. The obtained Pd/Pt(1 1 1) films structure also corresponds to the presence of non-equivalent hydrogen insertion sites, surely contributing to the slope observed in the two-phase domain

Puzzle Pieces: Neural Structure and Function in Prader-Willi Syndrome

Science.gov (United States)

Manning, Katherine E.; Holland, Anthony J.

2015-01-01

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder of genomic imprinting, presenting with a behavioural phenotype encompassing hyperphagia, intellectual disability, social and behavioural difficulties, and propensity to psychiatric illness. Research has tended to focus on the cognitive and behavioural investigation of these features, and, with the exception of eating behaviour, the neural physiology is currently less well understood. A systematic review was undertaken to explore findings relating to neural structure and function in PWS, using search terms designed to encompass all published articles concerning both in vivo and post-mortem studies of neural structure and function in PWS. This supported the general paucity of research in this area, with many articles reporting case studies and qualitative descriptions or focusing solely on the overeating behaviour, although a number of systematic investigations were also identified. Research to date implicates a combination of subcortical and higher order structures in PWS, including those involved in processing reward, motivation, affect and higher order cognitive functions, with both anatomical and functional investigations indicating abnormalities. It appears likely that PWS involves aberrant activity across distributed neural networks. The characterisation of neural structure and function warrants both replication and further systematic study. PMID:28943631

Puzzle Pieces: Neural Structure and Function in Prader-Willi Syndrome

Directory of Open Access Journals (Sweden)

Katherine E. Manning

2015-12-01

Full Text Available Prader-Willi syndrome (PWS is a neurodevelopmental disorder of genomic imprinting, presenting with a behavioural phenotype encompassing hyperphagia, intellectual disability, social and behavioural difficulties, and propensity to psychiatric illness. Research has tended to focus on the cognitive and behavioural investigation of these features, and, with the exception of eating behaviour, the neural physiology is currently less well understood. A systematic review was undertaken to explore findings relating to neural structure and function in PWS, using search terms designed to encompass all published articles concerning both in vivo and post-mortem studies of neural structure and function in PWS. This supported the general paucity of research in this area, with many articles reporting case studies and qualitative descriptions or focusing solely on the overeating behaviour, although a number of systematic investigations were also identified. Research to date implicates a combination of subcortical and higher order structures in PWS, including those involved in processing reward, motivation, affect and higher order cognitive functions, with both anatomical and functional investigations indicating abnormalities. It appears likely that PWS involves aberrant activity across distributed neural networks. The characterisation of neural structure and function warrants both replication and further systematic study.

In Situ Study of Thermal Stability of Copper Oxide Nanowires at Anaerobic Environment

Directory of Open Access Journals (Sweden)

Lihui Zhang

2014-01-01

Full Text Available Many metal oxides with promising electrochemical properties were developed recently. Before those metal oxides realize the use as an anode in lithium ion batteries, their thermal stability at anaerobic environment inside batteries should be clearly understood for safety. In this study, copper oxide nanowires were investigated as an example. Several kinds of in situ experiment methods including in situ optical microscopy, in situ Raman spectrum, and in situ transmission electron microscopy were adopted to fully investigate their thermal stability at anaerobic environment. Copper oxide nanowires begin to transform as copper(I oxide at about 250°C and finish at about 400°C. The phase transformation proceeds with a homogeneous nucleation.

Connectivity and functional profiling of abnormal brain structures in pedophilia.

Science.gov (United States)

Poeppl, Timm B; Eickhoff, Simon B; Fox, Peter T; Laird, Angela R; Rupprecht, Rainer; Langguth, Berthold; Bzdok, Danilo

2015-06-01

Despite its 0.5-1% lifetime prevalence in men and its general societal relevance, neuroimaging investigations in pedophilia are scarce. Preliminary findings indicate abnormal brain structure and function. However, no study has yet linked structural alterations in pedophiles to both connectional and functional properties of the aberrant hotspots. The relationship between morphological alterations and brain function in pedophilia as well as their contribution to its psychopathology thus remain unclear. First, we assessed bimodal connectivity of structurally altered candidate regions using meta-analytic connectivity modeling (MACM) and resting-state correlations employing openly accessible data. We compared the ensuing connectivity maps to the activation likelihood estimation (ALE) maps of a recent quantitative meta-analysis of brain activity during processing of sexual stimuli. Second, we functionally characterized the structurally altered regions employing meta-data of a large-scale neuroimaging database. Candidate regions were functionally connected to key areas for processing of sexual stimuli. Moreover, we found that the functional role of structurally altered brain regions in pedophilia relates to nonsexual emotional as well as neurocognitive and executive functions, previously reported to be impaired in pedophiles. Our results suggest that structural brain alterations affect neural networks for sexual processing by way of disrupted functional connectivity, which may entail abnormal sexual arousal patterns. The findings moreover indicate that structural alterations account for common affective and neurocognitive impairments in pedophilia. The present multimodal integration of brain structure and function analyses links sexual and nonsexual psychopathology in pedophilia. © 2015 Wiley Periodicals, Inc.

In situ transmission electron microscopy study of the microstructural origins for the electric field-induced phenomena in ferroelectric perovskites

Energy Technology Data Exchange (ETDEWEB)

Guo, Hanzheng [Iowa State Univ., Ames, IA (United States)

2014-12-15

Ferroelectrics are important materials due to their extensive technological applications, such as non-volatile memories, field-effect transistors, ferroelectric tunneling junctions, dielectric capacitors, piezoelectric transducers, sensors and actuators. As is well known, the outstanding dielectric, piezoelectric, and ferroelectric properties of these functional oxides originate from their ferroelectric domain arrangements and the corresponding evolution under external stimuli (e.g. electric field, stress, and temperature). Electric field has been known as the most efficient stimulus to manipulate the ferroelectric domains through polarization switching and alignment. Therefore, direct observation of the dynamic process of electric field-induced domain evolution and crystal structure transformation is of significant importance to understand the microstructural mechanisms for the functional properties of ferroelectrics. In this dissertation, electric field in situ transmission electron microscopy (TEM) technique was employed to monitor the real-time evolution of the domain morphology and crystal structure during various electrical processes: (1) the initial poling process, (2) the electric field reversal process, and (3) the electrical cycling process. Two types of perovskite-structured ceramics, normal ferroelectrics and relaxor ferroelectrics, were used for this investigation. In addition to providing the microscopic insight for some wellaccepted phase transformation rules, discoveries of some new or even unexpected physical phenomena were also demonstrated.

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

Science.gov (United States)

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.

New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Polymer Complex.

Science.gov (United States)

Jerkovic, Ivona; Koncar, Vladan; Grancaric, Ana Marija

2017-10-10

Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart textile structures seems to be a very promising solution for in situ structural health monitoring of composite parts. In order to optimize composites' quality and their lifetime all the production steps have to be monitored in real time. Textile sensors embedded in the composite reinforcement and having the same mechanical properties as the yarns used to make the reinforcement exhibit actuating and sensing capabilities. This paper presents a new generation of textile fibrous sensors based on the conductive polymer complex poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) developed by an original roll to roll coating method. Conductive coating for yarn treatment was defined according to the preliminary study of percolation threshold of this polymer complex. The percolation threshold determination was based on conductive dry films' electrical properties analysis, in order to develop highly sensitive sensors. A novel laboratory equipment was designed and produced for yarn coating to ensure effective and equally distributed coating of electroconductive polymer without distortion of textile properties. The electromechanical properties of the textile fibrous sensors confirmed their suitability for in situ structural damages detection of textile reinforced thermoplastic composites in real time.

Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia, Universita di Firenze, Via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it

2009-04-03

The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: {alpha}{sub a} = 1.5 x 10{sup -5} K{sup -1}, {alpha}{sub b} = 3.0 x 10{sup -5} K{sup -1}, {alpha}{sub c} = 2.2 x 10{sup -5} K{sup -1}, and the bulk thermal expansion coefficient {alpha}{sub V} is 5.4 x 10{sup -5} K{sup -1} for the temperature range 298-463 K.

Resonance contribution to electromagnetic structure functions

International Nuclear Information System (INIS)

Bowling, A.L. Jr.

1974-01-01

The part of the pion and proton electromagnetic structure functions due to direct channel resonances in the virtual Compton amplitude is discussed. After a phenomenological discussion, based on the work of Bloom and Gilman, of resonance production in inelastic electroproduction, the single resonance contribution to the pion and proton structure functions is expressed in terms of transition form factors. Froissart-Gribov representations of the Compton amplitude partial waves are presented and are used to specify the spin dependence of the transition form factors. The dependence of the form factors on momentum transfer and resonance mass is assumed on the basis of the behavior of exclusive resonance electroproduction. The single resonance contributions are summed in the Bjorken limit, and the result exhibits Bjorken scaling. Transverse photons are found to dominate in the Bjorken limit, and the threshold behavior of the resonant part of the structure functions is related to the asymptotic behavior of exclusive form factors at large momentum transfer. The resonant parts of the annihilation structure functions are not in general given by simple analytic continuation in the scaling vari []ble ω' of the electroproduction structure functions. (Diss. Abstr. Int., B)

Age-related reorganization of functional networks for successful conflict resolution: a combined functional and structural MRI study.

Science.gov (United States)

Schulte, Tilman; Müller-Oehring, Eva M; Chanraud, Sandra; Rosenbloom, Margaret J; Pfefferbaum, Adolf; Sullivan, Edith V

2011-11-01

Aging has readily observable effects on the ability to resolve conflict between competing stimulus attributes that are likely related to selective structural and functional brain changes. To identify age-related differences in neural circuits subserving conflict processing, we combined structural and functional MRI and a Stroop Match-to-Sample task involving perceptual cueing and repetition to modulate resources in healthy young and older adults. In our Stroop Match-to-Sample task, older adults handled conflict by activating a frontoparietal attention system more than young adults and engaged a visuomotor network more than young adults when processing repetitive conflict and when processing conflict following valid perceptual cueing. By contrast, young adults activated frontal regions more than older adults when processing conflict with perceptual cueing. These differential activation patterns were not correlated with regional gray matter volume despite smaller volumes in older than young adults. Given comparable performance in speed and accuracy of responding between both groups, these data suggest that successful aging is associated with functional reorganization of neural systems to accommodate functionally increasing task demands on perceptual and attentional operations. Copyright © 2009 Elsevier Inc. All rights reserved.

Phenomenology of the electron structure function

International Nuclear Information System (INIS)

Slominski, W.; Szwed, J.

2001-01-01

The advantages of introducing the electron structure function (ESF) in electron induced processes are demonstrated. Contrary to the photon structure function it is directly measured in such processes. At present energies, a simultaneous analysis of both the electron and the photon structure functions gives an important test of the experimentally applied methods. Estimates of the ESF at LEP momenta are given. At very high momenta contributions from W and Z bosons together with γ-Z interference can be observed. Predictions for the next generation of experiments are given. (orig.)

Ability of nitrones of various structures to control the radical polymerization of styrene mediated by in situ formed nitroxides.

NARCIS (Netherlands)

Sciannamea, V.; Guerrero-Sanchez, C.A.; Schubert, U.S.; Catala, J.-M.; Jerome, R.; Detrembleur, C.

2005-01-01

The ability of several nitrones to control the radical polymerization of styrene at 110 °C has been investigated by high-throughput experimentation. The nitrone/free radical initiator pair dictates the structure of the nitroxide and the alkoxyamine formed in situ, which determines the position of

Edge-functionalization of armchair graphene nanoribbons with pentagonal-hexagonal edge structures.

Science.gov (United States)

Ryou, Junga; Park, Jinwoo; Kim, Gunn; Hong, Suklyun

2017-06-21

Using density functional theory calculations, we have studied the edge-functionalization of armchair graphene nanoribbons (AGNRs) with pentagonal-hexagonal edge structures. While the AGNRs with pentagonal-hexagonal edge structures (labeled (5,6)-AGNRs) are metallic, the edge-functionalized (5,6)-AGNRs with substitutional atoms opens a band gap. We find that the band structures of edge-functionalized (5,6)-N-AGNRs by substitution resemble those of defect-free (N-1)-AGNR at the Γ point, whereas those at the X point show the original ones of the defect-free N-AGNR. The overall electronic structures of edge-functionalized (5,6)-AGNRs depend on the number of electrons, supplied by substitutional atoms, at the edges of functionalized (5,6)-AGNRs.

Structure and function of mammalian cilia

DEFF Research Database (Denmark)

Satir, Peter; Christensen, Søren T

2008-01-01

In the past half century, beginning with electron microscopic studies of 9 + 2 motile and 9 + 0 primary cilia, novel insights have been obtained regarding the structure and function of mammalian cilia. All cilia can now be viewed as sensory cellular antennae that coordinate a large number...

In situ scanning probe spectroscopy at nanoscale solid/liquid interfaces

International Nuclear Information System (INIS)

Schindler, W.; Hugelmann, M.; Hugelmann, Ph.

2005-01-01

Electrochemistry provides unique features for the preparation of low-dimensional structures, but in situ spectroscopy with atomic/molecular resolution at such structures is at present not well established yet. This paper shows that in situ scanning probe spectroscopy at solid/liquid interfaces can be utilized to study electronic properties at nanoscale, if appropriate conditions are applied. Tunneling spectroscopy provides information about tunneling barrier heights and electronic states in the tunneling gap, as shown on Au(1 1 1) substrates, contact spectroscopy allows for transport measurements at single nanostructures, as shown at Au/n-Si(1 1 1) nanodiodes. The influence of the electrolytic environment on spectroscopic investigations is not a principal limitation, but offers additional degrees of freedom, which allow, for example, spectroscopic studies of potential dependent surface phenomena at solid/liquid interfaces

In situ analysis and structural elucidation of sainfoin (Onobrychis viciifolia) tannins for high-throughput germplasm screening.

Science.gov (United States)

Gea, An; Stringano, Elisabetta; Brown, Ron H; Mueller-Harvey, Irene

2011-01-26

A rapid thiolytic degradation and cleanup procedure was developed for analyzing tannins directly in chlorophyll-containing sainfoin ( Onobrychis viciifolia ) plants. The technique proved suitable for complex tannin mixtures containing catechin, epicatechin, gallocatechin, and epigallocatechin flavan-3-ol units. The reaction time was standardized at 60 min to minimize the loss of structural information as a result of epimerization and degradation of terminal flavan-3-ol units. The results were evaluated by separate analysis of extractable and unextractable tannins, which accounted for 63.6-113.7% of the in situ plant tannins. It is of note that 70% aqueous acetone extracted tannins with a lower mean degree of polymerization (mDP) than was found for tannins analyzed in situ. Extractable tannins had between 4 and 29 lower mDP values. The method was validated by comparing results from individual and mixed sample sets. The tannin composition of different sainfoin accessions covered a range of mDP values from 16 to 83, procyanidin/prodelphinidin (PC/PD) ratios from 19.2/80.8 to 45.6/54.4, and cis/trans ratios from 74.1/25.9 to 88.0/12.0. This is the first high-throughput screening method that is suitable for analyzing condensed tannin contents and structural composition directly in green plant tissue.

Lumbar muscle structure and function in chronic versus recurrent low back pain: a cross-sectional study.

Science.gov (United States)

Goubert, Dorien; De Pauw, Robby; Meeus, Mira; Willems, Tine; Cagnie, Barbara; Schouppe, Stijn; Van Oosterwijck, Jessica; Dhondt, Evy; Danneels, Lieven

2017-09-01

Heterogeneity exists within the low back pain (LBP) population. Some patients recover after every pain episode, whereas others suffer daily from LBP complaints. Until now, studies rarely make a distinction between recurrent low back pain (RLBP) and chronic low back pain (CLBP), although both are characterized by a different clinical picture. Clinical experiences also indicate that heterogeneity exists within the CLBP population. Muscle degeneration, like atrophy, fat infiltration, alterations in muscle fiber type, and altered muscle activity, compromises proper biomechanics and motion of the spinal units in LBP patients. The amount of alterations in muscle structure and muscle function of the paraspinal muscles might be related to the recurrence or chronicity of LBP. The aim of this experimental study is to evaluate differences in muscle structure (cross-sectional area and lean muscle fat index) and muscle activity of the multifidus (MF) and erector spinae (ES) during trunk extension, in patients with RLBP, non-continuous CLBP, and continuous CLBP. This cross-sectional study took place in the university hospital of Ghent, Belgium. Muscle structure characteristics and muscle activity were assessed by magnetic resonance imaging (MRI). Fifty-five adults with non-specific LBP (24 RLBP in remission, 15 non-continuous CLBP, 16 continuous CLBP) participated in this study. Total cross-sectional area, muscle cross-sectional area, fat cross-sectional area, lean muscle fat index, T2-rest and T2-shift were assessed. A T1-weighted Dixon MRI scan was used to evaluate spinal muscle cross-sectional area and fat infiltration in the lumbar MF and ES. Muscle functional MRI was used to evaluate the muscle activity of the lumbar MF and ES during a lumbar extension exercise. Before and after the exercise, a pain assessment was performed. This study was supported by grants from the Special Research Fund of Ghent University (DEF12/AOP/022) without potential conflict of interest

Correlative studies of structural and functional imaging in primary progressive aphasia.

Science.gov (United States)

Panegyres, P K; McCarthy, M; Campbell, A; Lenzo, N; Fallon, M; Thompson, J

2008-01-01

To compare and contrast structural and functional imaging in primary progressive aphasia (PPA). A cohort of 8 patients diagnosed with PPA presenting with nonfluency were prospectively evaluated. All patients had structural imaging in the form of MRI and in 1 patient CAT scanning on account of a cardiac pacemaker. All patients had single-photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging. SPECT and PET imaging had 100% correlation. Anatomical imaging was abnormal in only 6 of the 8 patients. Wernicke's area showed greater peak Z score reduction and extent of area affected than Broca's area (McNemar paired test: P = .008 for Z score reduction; P = .0003 for extent). PET scanning revealed significant involvement of the anterior cingulum. Functional imaging in PPA: (a) identified more patients correctly than anatomic imaging highlighting the importance of SPECT and PET in the diagnosis; and (b) demonstrated the heterogeneous involvement of disordered linguistic networks in PPA suggesting its syndromic nature.

Neuropsychological functioning and brain structure in schizophrenia.

Science.gov (United States)

Crespo-Facorro, Benedicto; Barbadillo, Laura; Pelayo-Terán, José Maria; Rodríguez-Sánchez, José Manuel

2007-08-01

Cognitive deficits are core features of schizophrenia that are already evident at early phases of the illness. The study of specific relationships between cognition and brain structure might provide valuable clues about neural basis of schizophrenia and its phenomenology. The aim of this article was to review the most consistent findings of the studies exploring the relationships between cognitive deficits and brain anomalies in schizophrenia. Besides several important methodological shortcomings to bear in mind before drawing any consistent conclusion from the revised literature, we have attempted to systematically summarize these findings. Thus, this review has revealed that whole brain volume tends to positively correlate with a range of cognitive domains in healthy volunteers and female patients. An association between prefrontal morphological characteristics and general inability to control behaviour seems to be present in schizophrenia patients. Parahippocampal volume is related to semantic cognitive functions. Thalamic anomalies have been associated with executive deficits specifically in patients. Available evidence on the relationship between cognitive functions and cerebellar structure is still contradictory. Nonetheless, a larger cerebellum appears to be associated with higher IQ in controls and in female patients. Enlarged ventricles, including lateral and third ventricles, are associated with deficits in attention, executive and premorbid cognitive functioning in patients. Several of these reported findings seem to be counterintuitive according to neural basis of cognitive functioning drawn from animal, lesion, and functional imaging investigations. Therefore, there is still a great need for more methodologically stringent investigations that would help in the advance of our understanding of the cognition/brain structure relationships in schizophrenia.

Renaissance of morphological studies: the examination of functional structures in living animal organs using the in vivo cryotechnique.

Science.gov (United States)

Ohno, Shinichi; Saitoh, Yurika; Ohno, Nobuhiko; Terada, Nobuo

2017-01-01

Medical and biological scientists wish to understand the in vivo structures of the cells and tissues that make up living animal organs, as well as the locations of their molecular components. Recently, the live imaging of animal cells and tissues with fluorescence-labeled proteins produced via gene manipulation has become increasingly common. Therefore, it is important to ensure that findings derived from histological or immunohistochemical tissue sections of living animal organs are compatible with those obtained from live images of the same organs, which can be assessed using recently developed digital imaging techniques. Over the past two decades, we have performed immunohistochemical and morphological studies of the cells and tissues in living animal organs using a novel in vivo cryotechnique. The use of a specially designed liquid cryogen system with or without a cryoknife during this cryotechnique solved the technical problems that inevitably arise during the conventional preparation methods employed prior to light or electron microscopic examinations. Our in vivo cryotechnique has been found to be extremely useful for arresting transient physiological processes in cells and tissues and for maintaining their functional components-such as rapidly changing signaling molecules, membrane channels, or receptors-in situ. The purpose of the present review is to describe the basic mechanism underlying cryotechniques and the significance of our in vivo cryotechnique. In addition, it describes various morphological or immunohistochemical findings, observations made using quantum dots, and a Raman cryomicroscopy-based method for assessing oxygen saturation in the erythrocytes flowing through intestinal tissues.

Long-term carbon exclusion alters soil microbial function but not community structure across forests of contrasting productivity

Science.gov (United States)

Hart, S. C.; Dove, N. C.; Stark, J.

2017-12-01

While it is well-documented that distinct heterotrophic microbial communities emerge under different conditions of carbon (C) availability, the response of soil microbial communities and their function to long-term conditions of C exclusion in situ has yet to be investigated. We evaluated the role of C in controlling soil microbial communities and function by experimentally excluding plant C inputs for nine years at four forest sites along a productivity gradient in Oregon, USA. Carbon exclusion treatments were implemented by root trenching to a depth of 30 cm using 25-cm diameter steel pipe, and minimizing aboveground inputs as plant litter by covering the pipe with a 1-mm mesh screen. After nine years, we measured rates of gross and net nitrogen (N) transformations and microbial respiration in situ in the upper 15-cm of mineral soil in both C excluded plots and undisturbed control soils. We measured the soil total C and N concentration and potential extracellular enzyme activities. We used phospholipid fatty acid (PLFA) analysis to determine potential changes in the microbial community structure. Nine years of C exclusion reduced soil total C by about 20%, except at the highest productivity site where no statistically significant change was observed. Although PLFA community structure and microbial C were unchanged, microbial respiration was reduced by 15-45% at all sites. Similarly, specific extracellular enzyme activities for all enzymes increased at these sites with C exclusion, suggesting that the microbial communities were substrate-limited. Although gross N mineralization decreased under C exclusion, decreases in gross N immobilization were greater, resulting in increased net N mineralization rates in all but the lowest productivity site. Furthermore, C exclusion only increased net nitrification in the highest productivity site. Although these field-based results are largely consistent with previous laboratory studies indicating a strong coupling between C

Plasmodesmata: Structure and Function

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Thomas David Geydan

2006-07-01

Full Text Available Plasmodesmata are channels that transverse the cell wall and membrane. These specialized and non passive channels act like gates that facilitate and regulate both communication and transportation of molecules such as water, nutrients, metabolites and macromolecules between plant cells. In the last decade a new point of view of plasmodesmata has emerged, and studies have  demonstrated that these channels are more complex. In this brief note, we pretend to expose the actual knowledge of plasmodesmata, focusing on their structure and function.

Low-temperature thermal reduction of graphene oxide: In situ correlative structural, thermal desorption, and electrical transport measurements

Science.gov (United States)

Lipatov, Alexey; Guinel, Maxime J.-F.; Muratov, Dmitry S.; Vanyushin, Vladislav O.; Wilson, Peter M.; Kolmakov, Andrei; Sinitskii, Alexander

2018-01-01

Elucidation of the structural transformations in graphene oxide (GO) upon reduction remains an active and important area of research. We report the results of in situ heating experiments, during which electrical, mass spectrometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) measurements were carried out correlatively. The simultaneous electrical and temperature programmed desorption measurements allowed us to correlate the onset of the increase in the electrical conductivity of GO by five orders of magnitude at about 150 °C with the maxima of the rates of desorption of H2O, CO, and CO2. Interestingly, this large conductivity change happens at an intermediate level of the reduction of GO, which likely corresponds to the point when the graphitic domains become large enough to enable percolative electronic transport. We demonstrate that the gas desorption is intimately related to (i) the changes in the chemical structure of GO detected by XPS and Raman spectroscopy and (ii) the formation of nanoscopic holes in GO sheets revealed by TEM. These in situ observations provide a better understanding of the mechanism of the GO thermal reduction.

Convergent Findings of Altered Functional and Structural Brain Connectivity in Individuals with High Functioning Autism: A Multimodal MRI Study.

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Sophia Mueller

Full Text Available Brain tissue changes in autism spectrum disorders seem to be rather subtle and widespread than anatomically distinct. Therefore a multimodal, whole brain imaging technique appears to be an appropriate approach to investigate whether alterations in white and gray matter integrity relate to consistent changes in functional resting state connectivity in individuals with high functioning autism (HFA. We applied diffusion tensor imaging (DTI, voxel-based morphometry (VBM and resting state functional connectivity magnetic resonance imaging (fcMRI to assess differences in brain structure and function between 12 individuals with HFA (mean age 35.5, SD 11.4, 9 male and 12 healthy controls (mean age 33.3, SD 9.0, 8 male. Psychological measures of empathy and emotionality were obtained and correlated with the most significant DTI, VBM and fcMRI findings. We found three regions of convergent structural and functional differences between HFA participants and controls. The right temporo-parietal junction area and the left frontal lobe showed decreased fractional anisotropy (FA values along with decreased functional connectivity and a trend towards decreased gray matter volume. The bilateral superior temporal gyrus displayed significantly decreased functional connectivity that was accompanied by the strongest trend of gray matter volume decrease in the temporal lobe of HFA individuals. FA decrease in the right temporo-parietal region was correlated with psychological measurements of decreased emotionality. In conclusion, our results indicate common sites of structural and functional alterations in higher order association cortex areas and may therefore provide multimodal imaging support to the long-standing hypothesis of autism as a disorder of impaired higher-order multisensory integration.

In situ rheology of yeast biofilms.

Science.gov (United States)

Brugnoni, Lorena I; Tarifa, María C; Lozano, Jorge E; Genovese, Diego

2014-01-01

The aim of the present work was to investigate the in situ rheological behavior of yeast biofilms growing on stainless steel under static and turbulent flow. The species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time, with a predominance of C. krusei under static and turbulent flow. Likewise, structural variations occurred, with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness at 11 weeks (p < 0.001) and cell morphology was governed by hyphal structures and rounded cells. Using the in situ growth method introduced here, yeast biofilms were determined to be viscoelastic materials with a predominantly solid-like behavior, and neither this nor the G'0 values were significantly affected by the flow conditions or the growth time, and at large deformations their weak structure collapsed beyond a critical strain of about 1.5-5%. The present work could represent a starting point for developing in situ measurements of yeast rheology and contribute to a thin body of knowledge about fungal biofilm formation.

Structural and functional abnormalities of default mode network in minimal hepatic encephalopathy: a study combining DTI and fMRI.

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Rongfeng Qi

Full Text Available BACKGROUND AND PURPOSE: Live failure can cause brain edema and aberrant brain function in cirrhotic patients. In particular, decreased functional connectivity within the brain default-mode network (DMN has been recently reported in overt hepatic encephalopathy (HE patients. However, so far, little is known about the connectivity among the DMN in the minimal HE (MHE, the mildest form of HE. Here, we combined diffusion tensor imaging (DTI and resting-state functional MRI (rs-fMRI to test our hypothesis that both structural and functional connectivity within the DMN were disturbed in MHE. MATERIALS AND METHODS: Twenty MHE patients and 20 healthy controls participated in the study. We explored the changes of structural (path length, tracts count, fractional anisotropy [FA] and mean diffusivity [MD] derived from DTI tractography and functional (temporal correlation coefficient derived from rs-fMRI connectivity of the DMN in MHE patients. Pearson correlation analysis was performed between the structural/functional indices and venous blood ammonia levels/neuropsychological tests scores of patients. All thresholds were set at P<0.05, Bonferroni corrected. RESULTS: Compared to the healthy controls, MHE patients showed both decreased FA and increased MD in the tract connecting the posterior cingulate cortex/precuneus (PCC/PCUN to left parahippocampal gyrus (PHG, and decreased functional connectivity between the PCC/PCUN and left PHG, and medial prefrontal cortex (MPFC. MD values of the tract connecting PCC/PCUN to the left PHG positively correlated to the ammonia levels, the temporal correlation coefficients between the PCC/PCUN and the MPFC showed positive correlation to the digital symbol tests scores of patients. CONCLUSION: MHE patients have both disturbed structural and functional connectivity within the DMN. The decreased functional connectivity was also detected between some regions without abnormal structural connectivity, suggesting that the

Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Tang, Mingyi [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Xu, Xiaoyang, E-mail: xiaoyangxu2012@163.com [School of Science, Tianjin University, Tianjin 30072 (China); Wu, Tao [School of Science, Tianjin University, Tianjin 30072 (China); Zhang, Sai; Li, Xianxian [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Li, Yi, E-mail: liyi@tju.edu.cn [School of Science, Tianjin University, Tianjin 30072 (China)

2014-12-15

Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide.

Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

International Nuclear Information System (INIS)

Tang, Mingyi; Xu, Xiaoyang; Wu, Tao; Zhang, Sai; Li, Xianxian; Li, Yi

2014-01-01

Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide

Factor structure of cognition and functional capacity in two studies of schizophrenia and bipolar disorder: Implications for genomic studies.

Science.gov (United States)

Harvey, Philip D; Aslan, Mihaela; Du, Mengtian; Zhao, Hongyu; Siever, Larry J; Pulver, Ann; Gaziano, J Michael; Concato, John

2016-01-01

Impairments in cognition and everyday functioning are common in schizophrenia and bipolar disorder (BPD). In this article, we present factor analyses of cognitive and functional capacity (FC) measures based on 2 studies of schizophrenia (SCZ) and bipolar I disorder (BPI) using similar methods. The overall goal of these analyses was to determine whether performance-based assessments should be examined individually, or aggregated on the basis of the correlational structure of the tests, as well as to evaluate the similarity of factor structures of SCZ and BPI. Veterans Affairs Cooperative Studies Program Study #572 (Harvey et al., 2014) evaluated cognitive and FC measures among 5,414 BPI and 3,942 SCZ patients. A 2nd study evaluated similar neuropsychological (NP) and FC measures among 368 BPI and 436 SCZ patients. Principal components analysis, as well as exploratory and CFAs, were used to examine the data. Analyses in both datasets suggested that NP and FC measures were explained by a single underlying factor in BPI and SCZ patients, both when analyzed separately or as in a combined sample. The factor structure in both studies was similar, with or without inclusion of FC measures; homogeneous loadings were observed for that single factor across cognitive and FC domains across the samples. The empirically derived factor model suggests that NP performance and FC are best explained as a single latent trait applicable to people with SCZ and BPD. This single measure may enhance the robustness of the analyses relating genomic data to performance-based phenotypes. (c) 2015 APA, all rights reserved).

Analytical study on model tests of soil-structure interaction

International Nuclear Information System (INIS)

Odajima, M.; Suzuki, S.; Akino, K.

1987-01-01

Since nuclear power plant (NPP) structures are stiff, heavy and partly-embedded, the behavior of those structures during an earthquake depends on the vibrational characteristics of not only the structure but also the soil. Accordingly, seismic response analyses considering the effects of soil-structure interaction (SSI) are extremely important for seismic design of NPP structures. Many studies have been conducted on analytical techniques concerning SSI and various analytical models and approaches have been proposed. Based on the studies, SSI analytical codes (computer programs) for NPP structures have been improved at JINS (Japan Institute of Nuclear Safety), one of the departments of NUPEC (Nuclear Power Engineering Test Center) in Japan. These codes are soil-spring lumped-mass code (SANLUM), finite element code (SANSSI), thin layered element code (SANSOL). In proceeding with the improvement of the analytical codes, in-situ large-scale forced vibration SSI tests were performed using models simulating light water reactor buildings, and simulation analyses were performed to verify the codes. This paper presents an analytical study to demonstrate the usefulness of the codes

Effects of chronic inflammatory bowel diseases on left ventricular structure and function: a study protocol

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Botti Fiorenzo

2002-09-01

Full Text Available Abstract Background Experimental evidences suggest an increased collagen deposition in inflammatory bowel diseases (IBD. In particular, large amounts of collagen type I, III and V have been described and correlated to the development of intestinal fibrotic lesions. No information has been available until now about the possible increased collagen deposition far from the main target organ. In the hypothesis that chronic inflammation and increased collagen metabolism are reflected also in the systemic circulation, we aimed this study to evaluate the effects on left ventricular wall structure by assessing splancnic and systemic collagen metabolism (procollagen III assay, deposition (ultrasonic tissue characterization, and cardiac function (echocardiography in patients with different long standing history of IBD, before and after surgery. Methods Thirty patients affected by active IBD, 15 with Crohn and 15 with Ulcerative Colitis, submitted to surgery will be enrolled in the study in a double blind fashion. They will be studied before the surgical operation and 6, 12 months after surgery. A control group of 15 healthy age and gender-matched subjects will also be studied. At each interval blood samples will be collected in order to assess the collagen metabolism; a transthoracic echocardiogram will be recorded for the subsequent determination of cardiac function and collagen deposition. Discussion From this study protocol we expect additional information about the association between IBD and cardiovascular disorders; in particular to address the question if chronic inflammation, through the altered collagen metabolism, could affect left ventricular structure and function in a manner directly related to the estimated duration of the disease.

Long-Term Structural and Functional Myocardial Adaptations in Healthy Living Kidney Donors: A Pilot Study.

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Diego Bellavia

Full Text Available Compensatory renal hypertrophy following unilateral nephrectomy (UNX occurs in the remaining kidney. However, the long-term cardiac adaptive process to UNX remains poorly defined in humans. Our goal was to characterize myocardial structure and function in living kidney donors (LKDs, approximately 12 years after UNX.Cardiac function and structure in 15 Italian LKDs, at least 5 years after UNX (median time from donation = 8.4 years was investigated and compared to those of age and sex matched U.S. citizens healthy controls (n = 15. Standard and speckle tracking echocardiography (STE was performed in both LKDs and controls. Plasma angiotensin II, aldosterone, atrial natriuretic peptide (ANP, N terminus pro B-type natriuretic peptide (NT-proBNP, cyclic guanylyl monophosphate (cGMP, and amino-terminal peptide of procollagen III (PIIINP were also collected. Median follow-up was 11.9 years. In LKDs, LV geometry and function by STE were similar to controls, wall thickness and volumes were within normal limits also by CMR. In LKDs, CMR was negative for myocardial fibrosis, but apical rotation and LV torsion obtained by STE were impaired as compared to controls (21.4 ± 7.8 vs 32.7 ± 8.9 degrees, p = 0.04. Serum creatinine and PIIINP levels were increased [1.1 (0.9-1.3 mg/dL, and 5.8 (5.4-7.6] μg/L, respectively, while urinary cGMP was reduced [270 (250-355 vs 581 (437-698 pmol/mL] in LKDs. No LKD developed cardiovascular or renal events during follow-up.Long-term kidney donors have no apparent structural myocardial abnormalities as assessed by contrast enhanced CMR. However, myocardial deformation of the apical segments, as well as apical rotation, and LV torsion are reduced. The concomitant increase in circulating PIIINP level is suggestive of fibrosis. Further studies, focused on US and EU patients are warranted to evaluate whether these early functional modifications will progress to a more compromised cardiac function and structure at a later time.

Functional and structural impact of linuron on a freshwater community of primary producers: the use of immobilized algae

NARCIS (Netherlands)

Slijkerman, D.M.E.; Moreira-Santos, M.; Jak, R.G.; Ribeiro, R.; Soares, A.M.V.M.; Straalen, van N.M.

2005-01-01

An approach in determining ecosystem integrity and stress on ecosystem level is to assess processes within ecosystems. The aim of the present study was to evaluate the potential use of an in situ assay with immobilized Chlorella vulgaris as an indicator of effects on ecosystem functioning with

In situ ATR FTIR studies of SO4 adsorption on goethite in the presence of copper ions.

Science.gov (United States)

Beattie, D A; Chapelet, J K; Gräfe, M; Skinner, W M; Smith, E

2008-12-15

Despite the existence of many single ion sorption studies on iron and aluminum oxides, fewer studies have been reported that describe cosorption reactions. In this work, we present an in situ ATR FTIR study of synergistic adsorption of sulfate (SO4) and copper (Cu) on goethite, which is representative of the minerals and ions present in mine wastes, acid sulfate soils, and other industrial and agricultural settings. Sulfate adsorption was studied as a function of varying pH, and as a function of increasing concentration in the absence and presence of Cu. The presence of Cu ions in solution had a complex effect on the ability of SO4 ions to be retained on the goethite surface with increasing pH, with complete desorption occurring near pH 7 and 9 in the absence and presence of Cu, respectively. In addition, Cu ions altered the balance of inner vs outer sphere adsorbed SO4. The solid phase partitioning of SO4 at pH 3 and pH 5 was elevated by the presence of Cu; in both cases Cu increased the affinity of SO4 for the goethite surface. Complementary ex situ sorption edge studies of Cu on goethite in the absence and presence of SO4 revealed that the Cu adsorption edge shifted to lower pH (6.3 --> 5.6) in the presence of SO4, consistent with a decrease of the electrostatic repulsion between the goethite surface and adsorbing Cu. Based on the ATR FTIR and bulk sorption data we surmise that the cosorption products of SO4 and Cu at the goethite-water interface were not in the nature of ternary complexes under the conditions studied here. This information is critical for the evaluation of the onset of surface precipitates of copper-hydroxy sulfates as a function of pH and solution concentration.

Study on tertiary in-situ leachable uranium mineralization conditions in South Songliao basin

International Nuclear Information System (INIS)

Zhang Zhenqiang; Li Guokuan; Zhao Zonghua; Zhang Jingxun

2001-01-01

Tertiary in-situ leachable mineralization in Songliao Basin was analyzed in theory in the past. Since 1998, regional investigation at 1:200000 scale has been done with about 120 holes drilled. Based on drill holes recording, section compiling and sample analysis, the authors investigate into the Tertiary in-situ leachable conditions including rock character, sedimentary facies, rock chemistry, organic substances, uranium content, sandstone porosity, sandstone bodies, interlayer oxidation, and hydro-dynamic value. The study would play important role in prospecting for in-situ leachable uranium in South Songliao basin

Interhemispheric Functional and Structural Disconnection in Alzheimer's Disease: A Combined Resting-State fMRI and DTI Study.

Directory of Open Access Journals (Sweden)

Zhiqun Wang

Full Text Available Neuroimaging studies have demonstrated that patients with Alzheimer's disease presented disconnection syndrome. However, little is known about the alterations of interhemispheric functional interactions and underlying structural connectivity in the AD patients. In this study, we combined resting-state functional MRI and diffusion tensor imaging (DTI to investigate interhemispheric functional and structural connectivity in 16 AD, 16 mild cognitive impairment (MCI, as well as 16 cognitive normal healthy subjects (CN. The pattern of the resting state interhemispheric functional connectivity was measured with a voxel-mirrored homotopic connectivity (VMHC method. Decreased VMHC was observed in AD and MCI subjects in anterior brain regions including the prefrontal cortices and subcortical regions with a pattern of ADfunctional connectivity changes in the AD and MCI, which can be significantly correlated with the integrity changes in the midline white matter structures. These results suggest that VMHC can be used as a biomarker for the degeneration of the interhemispheric connectivity in AD.

In situ vitrification: Application to buried waste

International Nuclear Information System (INIS)

Callow, R.A.; Thompson, L.E.

1991-01-01

Two in situ vitrification field tests were conducted in June and July 1990 at Idaho National Engineering Laboratory. In situ vitrification is a technology for in-place conversion of contaminated soils into a durable glass and crystalline waste form and is being investigated as a potential remediation technology for buried waste. The overall objective of the two tests was to assess the general suitability of the process to remediate buried waste structures found at Idaho National Engineering Laboratory. In particular, these tests were designed as part of a treatability study to provide essential information on field performance of the process under conditions of significant combustible and metal wastes, and to test a newly developed electrode feed technology. The tests were successfully completed, and the electrode feed technology provided valuable operational control for successfully processing the high metal content waste. The results indicate that in situ vitrification is a feasible technology for application to buried waste. 2 refs., 5 figs., 2 tabs

Photon structure functions with heavy particle mass effects

Energy Technology Data Exchange (ETDEWEB)

Uematsu, Tsuneo, E-mail: uematsu@scphys.kyoto-u.jp [Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto, 606-8502 (Japan); Maskawa Institute for Science and Culture, Kyoto Sangyo University, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)

2013-01-15

In the framework of the perturbative QCD we investigate heavy particle mass effects on the unpolarized and polarized photon structure functions, F{sub 2}{sup γ} and g{sub 1}{sup γ}, respectively. We present our basic formalism to treat heavy particle mass effects to NLO in perturbative QCD. We also study heavy quark effects on the QCD sum rule for the first moment of g{sub 1}{sup γ}, which is related to axial anomaly. The photon structure function in supersymmetric QCD is also briefly discussed.

Structural characterizaiton and gas reactions of small metal particles by high-resolution, in-situ TEM and TED

Science.gov (United States)

1984-01-01

The existing in-situ transmission electron microscopy (TEM) facility was improved by adding a separately pumped mini-specimen chamber. The chamber contains wire-evaporation sources for three metals and a specimen heater for moderate substrate temperatures. A sample introduction device was constructed, installed, and tested, facilitating rapid introduction of a specimen into the mini-chamber while maintaining the background pressure in that chamber in the 10(-9) millibar range. Small particles and clusters of Pd, grown by deposition from the vapor phase in an in-situ TEM facility on amorphous and crystalline support films of alumina and on ultra-thin carbon films, were analyzed by conventional high-resolution TEM and image analysis in terms of detectability, number density, and size distribution. The smallest particles that could be detected and counted contained no more than 6 atoms; size determinations could be made for particles 1 nm in diameter. The influence of various oxygen plasma treatments, annealing treatments, and of increasing the substrate temperature during deposition was investigated. The TEM technique was employed to demonstrate that under otherwise identica l conditions the lattice parameter of Pd particles in the 1 to 2 nm size range and supported in random orientation on ex-situ prepared mica films is expanded by some 3% when compared to 5 nm size particles. It is believed that this expansion is neither a small-particle diffraction effect nor due to pseudomorphism, but that it is due to a annealing-induced transformation of the small as-deposited particles with predominantly composite crystal structures into larger particles with true f.c.c. structure and thus inherently smaller lattice parameter.

Feasibility study of structured diagnosis methods for functional dyspepsia in Korean medicine clinics

Directory of Open Access Journals (Sweden)

Jeong Hwan Park

2017-12-01

Full Text Available Background: Functional dyspepsia (FD is the seventh most common disease encountered in Korean medicine (KM clinics. Despite the large number of FD patients visiting KM clinics, the accumulated medical records have no utility in evidence development, due to being unstructured. This study aimed to construct a standard operating procedure (SOP with appropriate structured diagnostic methods for FD, and assess the feasibility for use in KM clinics. Methods: Two rounds of professional surveys were conducted by 10 Korean internal medicine professors to select the representative diagnostic methods. A feasibility study was conducted to evaluate compliance and time required for using the structured diagnostic methods by three specialists in two hospitals. Results: As per the results of the professional survey, five questionnaires and one basic diagnostic method were selected. An SOP was constructed based on the survey results, and a feasibility study showed that the SOP compliance score (out of 5 was 3.45 among the subjects, and 3.25 among the practitioners. The SOP was acceptable and was not deemed difficult to execute. The total execution time was 136.5 minutes, out of which the gastric emptying test time was 129 minutes. Conclusion: This feasibility study of the SOP with structured diagnostic methods for FD confirmed it was adequate for use in KM clinics. It is expected that these study findings will be helpful to clinicians who wish to conduct observational studies as well as to generate quantitative medical records to facilitate Big Data research. Keywords: Big Data, Dyspepsia, Korean medicine, Feasibility studies, Observational study

A flexible multi-stimuli in situ (S)TEM: Concept, optical performance, and outlook

International Nuclear Information System (INIS)

Börrnert, Felix; Müller, Heiko; Riedel, Thomas; Linck, Martin; Kirkland, Angus I.; Haider, Max.; Büchner, Bernd; Lichte, Hannes

2015-01-01

The progress in (scanning) transmission electron microscopy development had led to an unprecedented knowledge of the microscopic structure of functional materials at the atomic level. Additionally, although not widely used yet, electron holography is capable to map the electric and magnetic potential distributions at the sub-nanometer scale. Nevertheless, in situ studies inside a (scanning) transmission electron microscope ((S)TEM) are extremely challenging because of the much restricted size and accessibility of the sample space. Here, we introduce a concept for a dedicated in situ (S)TEM with a large sample chamber for flexible multi-stimuli experimental setups and report about the electron optical performance of the instrument. We demonstrate a maximum resolving power of about 1 nm in conventional imaging mode and substantially better than 5 nm in scanning mode while providing an effectively usable “pole piece gap” of 70 mm. - Highlights: • A concept for a (S)TEM with a large sample chamber is outlined. • An actual microscope is modified and has now a 70 mm high sample space. • The resolving power is about 1 nm in TEM and better than 5 nm in STEM mode. • Possible dedicated in situ microscopes with present technology are discussed

A flexible multi-stimuli in situ (S)TEM: Concept, optical performance, and outlook

Energy Technology Data Exchange (ETDEWEB)

Börrnert, Felix, E-mail: felix.boerrnert@triebenberg.de [Speziallabor Triebenberg, Technische Universität Dresden, 01062 Dresden (Germany); IFW Dresden, PF 27 01 16, 01171 Dresden (Germany); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Müller, Heiko; Riedel, Thomas; Linck, Martin [CEOS GmbH, Englerstraße 28, 69126 Heidelberg (Germany); Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Haider, Max. [CEOS GmbH, Englerstraße 28, 69126 Heidelberg (Germany); Büchner, Bernd [IFW Dresden, PF 27 01 16, 01171 Dresden (Germany); Lichte, Hannes [Speziallabor Triebenberg, Technische Universität Dresden, 01062 Dresden (Germany)

2015-04-15

The progress in (scanning) transmission electron microscopy development had led to an unprecedented knowledge of the microscopic structure of functional materials at the atomic level. Additionally, although not widely used yet, electron holography is capable to map the electric and magnetic potential distributions at the sub-nanometer scale. Nevertheless, in situ studies inside a (scanning) transmission electron microscope ((S)TEM) are extremely challenging because of the much restricted size and accessibility of the sample space. Here, we introduce a concept for a dedicated in situ (S)TEM with a large sample chamber for flexible multi-stimuli experimental setups and report about the electron optical performance of the instrument. We demonstrate a maximum resolving power of about 1 nm in conventional imaging mode and substantially better than 5 nm in scanning mode while providing an effectively usable “pole piece gap” of 70 mm. - Highlights: • A concept for a (S)TEM with a large sample chamber is outlined. • An actual microscope is modified and has now a 70 mm high sample space. • The resolving power is about 1 nm in TEM and better than 5 nm in STEM mode. • Possible dedicated in situ microscopes with present technology are discussed.

The Structure-Function Linkage Database.

Science.gov (United States)

Akiva, Eyal; Brown, Shoshana; Almonacid, Daniel E; Barber, Alan E; Custer, Ashley F; Hicks, Michael A; Huang, Conrad C; Lauck, Florian; Mashiyama, Susan T; Meng, Elaine C; Mischel, David; Morris, John H; Ojha, Sunil; Schnoes, Alexandra M; Stryke, Doug; Yunes, Jeffrey M; Ferrin, Thomas E; Holliday, Gemma L; Babbitt, Patricia C

2014-01-01

The Structure-Function Linkage Database (SFLD, http://sfld.rbvi.ucsf.edu/) is a manually curated classification resource describing structure-function relationships for functionally diverse enzyme superfamilies. Members of such superfamilies are diverse in their overall reactions yet share a common ancestor and some conserved active site features associated with conserved functional attributes such as a partial reaction. Thus, despite their different functions, members of these superfamilies 'look alike', making them easy to misannotate. To address this complexity and enable rational transfer of functional features to unknowns only for those members for which we have sufficient functional information, we subdivide superfamily members into subgroups using sequence information, and lastly into families, sets of enzymes known to catalyze the same reaction using the same mechanistic strategy. Browsing and searching options in the SFLD provide access to all of these levels. The SFLD offers manually curated as well as automatically classified superfamily sets, both accompanied by search and download options for all hierarchical levels. Additional information includes multiple sequence alignments, tab-separated files of functional and other attributes, and sequence similarity networks. The latter provide a new and intuitively powerful way to visualize functional trends mapped to the context of sequence similarity.

In situ hydrogen loading on zirconium powder

Energy Technology Data Exchange (ETDEWEB)

Maimaitiyili, Tuerdi, E-mail: tuerdi.maimaitiyili@mah.se; Blomqvist, Jakob [Malmö University, Östra Varvsgatan 11 A, Malmö, Skane 20506 (Sweden); Steuwer, Axel [Lund University, Ole Römers väg, Lund, Skane 22100 (Sweden); Nelson Mandela Metropolitan University, Gardham Avenue, Port Elizabeth 6031 (South Africa); Bjerkén, Christina [Malmö University, Östra Varvsgatan 11 A, Malmö, Skane 20506 (Sweden); Zanellato, Olivier [Ensam - Cnam - CNRS, 151 Boulevard de l’Hôpital, Paris 75013 (France); Blackmur, Matthew S. [Materials Performance Centre, School of Materials, The University of Manchester, Manchester M1 7HS (United Kingdom); Andrieux, Jérôme [European Synchrotron Radiation Facility, 6 rue J Horowitz, Grenoble 38043 (France); Université de Lyon, 43 Bd du 11 novembre 1918, Lyon 69100 (France); Ribeiro, Fabienne [Institut de Radioprotection et Sûreté Nucléaire, IRSN, BP 3, 13115 Saint-Paul Lez Durance (France)

2015-06-26

Commercial-grade Zr powder loaded with hydrogen in situ and phase transformations between various Zr and ZrH{sub x} phases have been monitored in real time. For the first time, various hydride phases in a zirconium–hydrogen system have been prepared in a high-energy synchrotron X-ray radiation beamline and their transformation behaviour has been studied in situ. First, the formation and dissolution of hydrides in commercially pure zirconium powder were monitored in real time during hydrogenation and dehydrogenation, then whole pattern crystal structure analysis such as Rietveld and Pawley refinements were performed. All commonly reported low-pressure phases presented in the Zr–H phase diagram are obtained from a single experimental arrangement.

In situ hydrogen loading on zirconium powder

International Nuclear Information System (INIS)

Maimaitiyili, Tuerdi; Blomqvist, Jakob; Steuwer, Axel; Bjerkén, Christina; Zanellato, Olivier; Blackmur, Matthew S.; Andrieux, Jérôme; Ribeiro, Fabienne

2015-01-01

Commercial-grade Zr powder loaded with hydrogen in situ and phase transformations between various Zr and ZrH x phases have been monitored in real time. For the first time, various hydride phases in a zirconium–hydrogen system have been prepared in a high-energy synchrotron X-ray radiation beamline and their transformation behaviour has been studied in situ. First, the formation and dissolution of hydrides in commercially pure zirconium powder were monitored in real time during hydrogenation and dehydrogenation, then whole pattern crystal structure analysis such as Rietveld and Pawley refinements were performed. All commonly reported low-pressure phases presented in the Zr–H phase diagram are obtained from a single experimental arrangement

Concepts and Relations in Neurally Inspired In Situ Concept-Based Computing.

Science.gov (United States)

van der Velde, Frank

2016-01-01

In situ concept-based computing is based on the notion that conceptual representations in the human brain are "in situ." In this way, they are grounded in perception and action. Examples are neuronal assemblies, whose connection structures develop over time and are distributed over different brain areas. In situ concepts representations cannot be copied or duplicated because that will disrupt their connection structure, and thus the meaning of these concepts. Higher-level cognitive processes, as found in language and reasoning, can be performed with in situ concepts by embedding them in specialized neurally inspired "blackboards." The interactions between the in situ concepts and the blackboards form the basis for in situ concept computing architectures. In these architectures, memory (concepts) and processing are interwoven, in contrast with the separation between memory and processing found in Von Neumann architectures. Because the further development of Von Neumann computing (more, faster, yet power limited) is questionable, in situ concept computing might be an alternative for concept-based computing. In situ concept computing will be illustrated with a recently developed BABI reasoning task. Neurorobotics can play an important role in the development of in situ concept computing because of the development of in situ concept representations derived in scenarios as needed for reasoning tasks. Neurorobotics would also benefit from power limited and in situ concept computing.

Optimizing structure in nanodiamonds using in-situ strain-sensitive Bragg coherent diffraction imaging.

Science.gov (United States)

Hruszkewycz, Stephan; Cha, Wonsuk; Ulvestad, Andrew; Fuoss, Paul; Heremans, F. Joseph; Harder, Ross; Andrich, Paolo; Anderson, Christopher; Awschalom, David

The nitrogen-vacancy center in diamond has attracted considerable attention for nanoscale sensing due to unique optical and spin properties. Many of these applications require diamond nanoparticles which contain large amounts of residual strain due to the detonation or milling process used in their fabrication. Here, we present experimental, in-situ observations of changes in morphology and internal strain state of commercial nanodiamonds during high-temperature annealing using Bragg coherent diffraction imaging to reconstruct a strain-sensitive 3D image of individual sub-micron-sized crystals. We find minimal structural changes to the nanodiamonds at temperatures less than 650 C, and that at higher temperatures up to 750 C, the diamond-structured volume fraction of nanocrystals tend to shrink. The degree of internal lattice distortions within nanodiamond particles also decreases during the anneal. Our findings potentially enable the design of efficient processing of commercial nanodiamonds into viable materials suitable for device design. We acknowledge support from U.S. DOE, Office of Science, BES, MSE.