Science.gov

Sample records for active layer morphology

  1. Grain sorting in the morphological active layer of a braided river physical model

    NASA Astrophysics Data System (ADS)

    Leduc, P.; Ashmore, P.; Gardner, J. T.

    2015-07-01

    A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer aggregated over the width of the river. This vertical sorting is important for analyzing braided river sedimentology, for numerical modeling of braided river morpho-dynamics and for measuring and predicting bed load transport rate. We define the morphological active layer as the bed material between the maximum and minimum bed elevations at a point over extended time periods sufficient for braiding processes to re-work the river bed. The vertical extent of the active layer was measured using 40 hourly high-resolution DEMs of the model river bed. An image texture algorithm was used to map bed material grain size of each DEM. Analysis of the 40 DEMs and texture maps provides data on the geometry of the morphological active layer and variation in grain size in three-dimensions. Normalizing active layer thickness and dividing into 10 sub-layers we show that all grain sizes occur with almost equal frequency in all sub-layers. Occurrence of patches and strings of coarser (or finer) material relates to preservation of particular morpho-textural features within the active layer. For numerical modeling and bed load prediction a morphological active layer that is fully mixed with respect to grain size is a reliable approximation.

  2. Grain sorting in the morphological active layer of a braided river physical model

    NASA Astrophysics Data System (ADS)

    Leduc, P.; Ashmore, P.; Gardner, J. T.

    2015-12-01

    A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer aggregated over the width of the river. This vertical sorting is important for analyzing braided river sedimentology, for numerical modeling of braided river morphodynamics, and for measuring and predicting bedload transport rate. We define the morphological active layer as the bed material between the maximum and minimum bed elevations at a point over extended time periods sufficient for braiding processes to rework the river bed. The vertical extent of the active layer was measured using 40 hourly high-resolution DEMs (digital elevation models) of the model river bed. An image texture algorithm was used to map bed material grain size of each DEM. Analysis of the 40 DEMs and texture maps provides data on the geometry of the morphological active layer and variation in grain size in three dimensions. By normalizing active layer thickness and dividing into 10 sublayers, we show that all grain sizes occur with almost equal frequency in all sublayers. Occurrence of patches and strings of coarser (or finer) material relates to preservation of particular morpho-textural features within the active layer. For numerical modeling and bedload prediction, a morphological active layer that is fully mixed with respect to grain size is a reliable approximation.

  3. Design of Bicontinuous Donor/Acceptor Morphologies for Use as Organic Solar Cell Active Layers

    NASA Astrophysics Data System (ADS)

    Kipp, Dylan; Mok, Jorge; Verduzco, Rafael; Ganesan, Venkat

    Two of the primary challenges limiting the marketability of organic solar cells are i) the smaller device efficiency of the organic solar cell relative to the conventional silicon-based solar cell and ii) the long term thermal instability of the device active layer. The achievement of equilibrium donor/acceptor morphologies with the characteristics believed to yield high device performance characteristics could address each of these two challenges. In this work, we present the results of a combined simulations and experiments-based approach to investigate if a conjugated BCP additive can be used to control the self-assembled morphologies taken on by conjugated polymer/PCBM mixtures. First, we use single chain in mean field Monte Carlo simulations to identify regions within the conjugated polymer/PCBM composition space in which addition of copolymers can lead to bicontinuous equilibrium morphologies with high interfacial areas and nanoscale dimensions. Second, we conduct experiments as directed by the simulations to achieve such morphologies in the PTB7 + PTB7- b-PNDI + PCBM model blend. We characterize the results of our experiments via a combination of transmission electron microscopy and X-ray scattering techniques and demonstrate that the morphologies from experiments agree with those predicted in simulations. Accordingly, these results indicate that the approach utilized represents a promising approach to intelligently design the morphologies taken on by organic solar cell active layers.

  4. Nanocomposites of polymers with layered inorganic nanofillers: Antimicrobial activity, thermo-mechanical properties, morphology, and dispersion

    NASA Astrophysics Data System (ADS)

    Songtipya, Ponusa

    In the first part of the thesis, polyethylene/layered silicate nanocomposites that exhibit an antimicrobial activity were synthesized and studied. Their antimicrobial activity was designed to originate from non-leaching, novel cationic modifiers---amine-based surfactants---used as the organic-modification of the fillers. Specifically, PE/organically-modified montmorillonite ( mmt) nanocomposites were prepared via melt-processing, and simultaneous dispersion and antimicrobial activity was designed by proper choice of the fillers' organic modification. The antimicrobial activity was measured against three micotoxinogen fungal strains (Penicillium roqueforti and claviforme, and Fusarium graminearum ). Various mmt-based organofillers, which only differ in the type or amount of their organic modification, were used to exemplify how these surfactants can be designed to render antifungal activity to the fillers themselves and the respective nanocomposites. A comparative discussion of the growth of fungi on unfilled PE and nanocomposite PE films is used to demonstrate how the antimicrobial efficacy is dictated by the surfactant chemistry and, further, how the nanocomposites' inhibitory activity compares to that of the organo-fillers and the surfactants. An attempt to improve the thermomechanical reinforcement of PE/mmt nanocomposites while maintaining their antimicrobial activity, was also carried out by combining two different organically modified montmorillonites. However, a uniform microscopic dispersion could not be achieved through this approach. In the second part of this thesis, a number of fundamental studies relating to structure-property relations in nanocomposites were carried out, towards unveiling strategies that can concurrently optimize selected properties of polymers by the addition of nanofillers. Specifically, the dispersion-crystallinity-reinforcement relations in HDPE/mmt nanocomposites was investigated. The influence of a functional HDPE compatibilizer

  5. Unpinning the Open-Circuit Voltage in Organic Solar Cells through Tuning Ternary Blend Active Layer Morphology

    NASA Astrophysics Data System (ADS)

    Khlyabich, Petr; Thompson, Barry; Loo, Yueh-Lin

    2015-03-01

    The use of ternary, as opposed to binary, blends having complementary absorption in active layers of organic bulk heterojunction solar cells is a simple approach to increase overall light absorption. While the open-circuit voltage (Voc) of such solar cells have generally been shown to be pinned by the smallest energy level difference between the donor and acceptor constituents, there have been materials systems, that when incorporated into active layers of solar cells, exhibit composition dependent and tunable Voc. Herein, we demonstrate that this Voc tunability in ternary blend solar cells is correlated with the morphology of the active layer. Chemical compatibility between the constituents in the blend, as probed by grazing-incidence X-ray diffraction (GIXD) measurements, affords Voc tuning. The constituents need not ``co-crystallize'' limited miscibility between the constituents in the active layers of solar cells affords Voc tunability. Poor physical interactions between the constituent domains within the active layers, on the other hand, result in devices that exhibit an invariant Voc that is pinned by the smallest energy level difference between the donor(s) and the acceptor(s). Our morphological studies thus support the proposed alloying model that was put forth originally.

  6. Investigating the effect of solvent boiling temperature on the active layer morphology of diffusive bilayer solar cells

    NASA Astrophysics Data System (ADS)

    Vohra, Varun; Dörling, Bernhard; Higashimine, Koichi; Murata, Hideyuki

    2016-01-01

    Using chlorobenzene as a base solvent for the deposition of the poly(3-hexylthiophene-2,5-diyl) (P3HT) layer in P3HT:phenyl-C61-butyric acid methyl ester diffusive bilayer solar cells, we investigate the effect of adding of small amounts of high-boiling-point solvents with similar chemical structures on the resulting active layer morphologies. The results demonstrate that the crystallinity of the P3HT films as well as the vertical donor-acceptor gradient in the active layer can be tuned by this approach. The use of high-boiling-point solvents improved all photovoltaic parameters and resulted in a 32% increase in power conversion efficiency.

  7. Aminosilane layers on the plasma activated thermoplastics: influence of solvent on its structure and morphology.

    PubMed

    Sunkara, Vijaya; Cho, Yoon-Kyoung

    2013-12-01

    The chemistry and the structure of aminosilane layer on the plasma activated thermoplastic substrates, e.g., polycarbonate (PC), polystyrene (PS), poly(methyl methacrylate) (PMMA), and cyclic olefin co-polymer (COC) were investigated at the molecular level. The nature of the surface functional groups of the silane layers prepared by solution phase deposition in aqueous and anhydrous solvents were studied using various techniques including ellipsometry, goniometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance infrared spectroscopy (ATR-IR). The XPS analyses revealed the presence of various oxygen functionalities on the plasma activated thermoplastics. Considerable differences were observed for the structure of aminosilane depending on the solvent used for the reaction. Deposition from aqueous solution resulted in relatively flat and smooth surfaces with consistent thickness compared to the anhydrous solution deposition. In the former case, 33% of the total nitrogen accounted for protonated amine and 16% for the free amino groups. In the latter, only 6% accounted for the protonated amine. The point of zero charge (pzc), on the aminosilane modified PC was found to be around 7, indicated that the surface is positively charged below pH 7 and negatively charged above pH 7. The surface analysis data suggested that various interactions are possible between the plasma activated thermoplastic surface and the aminosilane. In general, they are bound to the surface through covalent bond formation between the oxygen functionalities on the thermoplastic surface and the amino or the silanol groups of the aminosilane.

  8. Effect of Copolymer Chain Architecture on Active Layer Morphology and Device Performance

    NASA Astrophysics Data System (ADS)

    Amonoo, Jojo; Li, Anton; Sykes, Matthew; Huang, Bingyuan; Palermo, Edmund; McNeil, Anne; Shtein, Max; Green, Peter

    2014-03-01

    The optimum morphological structure that determines the device performance of bulk heterojunction thin film polymer solar cells is greatly influenced by the extent of phase separation between the polymer and fullerene components, which ultimately defines the length scales and purity of the donor- and acceptor-rich phases. Block copolymer thin films have been widely studied for their ability to microphase separate into well-defined nanostructures. Nickel-catalyzed chain-growth copolymerizations of thiophene and selenophene derivatives afforded well-defined π-conjugated copolymers of poly(3-hexylthiophene) (P3HT) and poly(3-hexylselenophene) (P3HS) to achieve diblock, random and gradient copolymer chain architectures. This allowed us to study the effect of copolymer sequence and nanoscale morphology of P3HT-P3HS copolymer/[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) on device performance. With the use of energy-filtered transmission electron microscopy and conductive and photoconductive atomic force microscopy we found that copolymer sequence strongly influences the phase separation capabilities of the copolymer-fullerene blend in bulk heterojunction organic photovoltaic devices.

  9. New Insights into Dynamics and Morphology of P3HT:PCBM Active Layers in Bulk Heterojunctions

    SciTech Connect

    Carrillo, Jan-Michael Y.; Kumar, Rajeev; Goswami, Monojoy; Sumpter, Bobby G.; Brown, W. Michael

    2013-08-30

    Organic photovoltaics (OPVs) are topic of extensive research for their potential application in solar cells. Recent work has led to the development of a coarse-grained model for studying poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends with molecular simulations. Here we provide further validation of the force field and use it to study the thermal annealing process of P3HT:PCBM blends. A key finding of our study is that, in contrast to a previous report, the annealing process does not converge at the short time scales reported. Rather, we find that the self assembly of the blends is characterized by three rate dependent stages that require much longer simulations to approach convergence. Using state-of-the- art high performance computing, we are able to study annealing at length and time scales commensurate with devices used in experiments. Our simulations show different phase segregated morphologies dependent on the P3HT chain length and PCBM volume fraction in the blend. For short chain lengths, we observed a smectic morphology containing alternate P3HT and PCBM domains. In contrast, a phase segregated morphology containing domains of P3HT and PCBM distributed randomly in space is found for longer chain lengths. Theoretical arguments justifying stabilization of these morphologies due to shape anisotropy of P3HT (rod-like) and PCBM (sphere-like) are presented. Furthermore, results on structure factor, miscibility of P3HT and PCBM, domain spacing and kinetics of phase segregation in the blends are presented in detail. Qualitative comparison of these results with small-angle neutron scattering experiments from literature is presented and an excellent agreement is found.

  10. Surface modification of nanoporous alumina layers by deposition of Ag nanoparticles. Effect of alumina pore diameter on the morphology of silver deposit and its influence on SERS activity

    NASA Astrophysics Data System (ADS)

    Pisarek, Marcin; Nowakowski, Robert; Kudelski, Andrzej; Holdynski, Marcin; Roguska, Agata; Janik-Czachor, Maria; Kurowska-Tabor, Elżbieta; Sulka, Grzegorz D.

    2015-12-01

    Self-organized Al2O3 nanoporous/nanotubular (Al2O3-NP) oxide layers decorated with silver nanoparticles (Ag-NPs) exhibiting specific properties may serve as attractive SERS substrates for investigating the interactions between an adsorbate and adsorbent, or as stable platforms for detecting various organic compounds. This article presents the influence of the size of the alumina nanopores with a deposit of silver nanoparticles obtained by the magnetron sputtering technique on the morphology of silver film. Moreover, the effect of pore diameter on the intensity of SERS spectra in Ag-NPs/Al2O3-NP/Al composites has also been estimated. For such investigations we used pyridine as a probe molecule, since it has a large cross-section for Raman scattering. To characterize the morphology of the composite oxide layer Ag-NPs/Al2O3-NP/Al, before and after deposition of Ag-NPs by PVD methods (Physical Vapor Deposition), we used scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface analytical technique of surface-enhanced Raman spectroscopy (SERS) was used to investigate the surface activity of the composite. The results obtained show that, for a carefully controlled amount of Ag (0.020 mg/cm2 - deposited on the top of alumina nanopores whose average size varies from ∼86 nm up to ∼320 nm) in the composites investigated, pore size significantly affects SERS enhancement. We obtained distinctly higher intensities of SERS spectra for substrates with an Ag-NPs deposit having a larger diameter of the alumina nanopores. AFM results suggest that both the lateral and perpendicular distribution of Ag-NPs within and on the top of the largest pores is responsible for the highest SERS activity of the resulting Ag-NPs/Al2O3-NP/Al composite layer, since it produces a variety of cavities and slits which function as resonators for the adsorbed molecules. The Ag-NPs/MeOx-NP/Me composite layers obtained ensure a good reproducibility of the SERS measurements. a

  11. Structural Characterization of Layered Morphologies in Precise Copolymers

    NASA Astrophysics Data System (ADS)

    Trigg, Edward; Gaines, Taylor; Wagener, Kenneth; Winey, Karen

    2015-03-01

    Layered morphologies have been observed in precise polyethylene-based copolymers that contain acid, charged, or polar functional groups precisely spaced along a linear alkane chain. Sufficiently long alkane segments form structures resembling orthorhombic polyethylene crystals, while the functional groups form 2-D layers that disrupt the alkane crystal structure to varying degrees. Here, layered morphologies in precise copolymers containing acrylic acid, phosphonic acid, imidazolium bromide, and sulfone groups are studied via X-ray scattering. Specifically, the composition profiles of the layered structures are obtained by Fourier synthesis, and the coherence length is investigated using peak width analysis. This analysis indicates that the layers of functional groups are frequently bordered by two crystallites, which suggests different dynamics relative to layers bordered by one crystalline and one amorphous microdomain. Detailed understanding of the structure of the layered morphologies will allow for a systematic investigation of proton and ion conductivity mechanisms, which are expected to occur through the high-dielectric layers.

  12. Investigation of the pore structure and morphology of cellulose acetate membranes using small-angle neutron scattering. 1: Cellulose acetate active layer membranes

    SciTech Connect

    Kulkarni, S.; Krause, S. ); Wignall, G.D. . Solid State Div.); Hammouda, B. . Center for High Resolution Neutron Scattering)

    1994-11-07

    The structure of ultrathin cellulose acetate membranes, known as active layer membranes, has been investigated using small-angle neutron scattering. These membranes are known to have structural and functional similarity to the surface or skin layer in commercial reverse-osmosis (RO) membranes and hence are useful model systems for understanding the structure of the RO membrane skin layer. Active layer membranes were studied after swelling them with either D[sub 2]O or CD[sub 3]OD. The results in both cases clearly indicated the presence of very small (10--20 [angstrom]) porous structures in the membrane. The presence of such pores has been a subject of long-standing controversy in this area. The data were analyzed using a modified Debye-Bueche analysis and the resultant membrane structure was seen to agree well with structural information from electron microscopic studies. Finally, a possible explanation for the differences in scattering observed between the D[sub 2]O swollen membranes and the CD[sub 3]OD swollen membranes has been presented.

  13. Interrelation of the construction of the metamorphic InAlAs/InGaAs nanoheterostructures with the InAs content in the active layer of 76-100% with their surface morphology and electrical properties

    SciTech Connect

    Vasil'evskii, I. S.; Galiev, G. B.; Klimov, E. A.; Kvanin, A. L.; Pushkarev, S. S. Pushkin, M. A.

    2011-09-15

    The influence of the construction of a metamorphic buffer on the surface morphology and electrical properties of InAlAs/InGaAs/InAlAs nanoheterostructures with InAs content in the active layer from 76 to 100% with the use of the GaAs and InP substrates is studied. It is shown that such parameters as the electron mobility and the concentration, as well as the root-mean-square surface roughness, substantially depend on the construction of the metamorphic buffer. It is established experimentally that these parameters largely depend on the maximal local gradient of the lattice constant of the metamorphic buffer in the growth direction of the layers rather than on its average value. It is shown that, with selection of the construction of the metamorphic buffer, it is possible to form nanostructured surfaces with a large-periodic profile.

  14. Morphology Control of Zinc Oxide Nanostructure on Single Layer Graphene.

    PubMed

    Ahn, Seungbae; Vijayarangamuthu, K; Jeon, Ki-Jeon

    2016-05-01

    Various morphologies of zinc oxide (ZnO) nanostructures on single layer graphene were synthesized by electrodeposition method. The current density was utilized to control the morphology of the ZnO. The Scanning Electron Microscope (SEM) was used to examine the surface morphology of the samples. SEM analysis shows morphology changes to nanorod, flower, and flakes with increase in the current density from 0.1, 0.2, and 0.3 mA/cm(-1) respectively. The XRD, XPS, and Raman spectroscopy were adopted to characterize the ZnO nanostructure and to understand the formation of various morphologies. The Raman result clearly shows extra modes due to for flakes structure caused by c-axis orientation along the substrate direction. Further, XPS data also supports formation of ZnO without any other intermediate compound such as Zn(OH)2. The formation of various morphologies was correlated to the formation different ratio of Zn2+ and OH- ions and the change in growth direction due to various current densities. PMID:27483766

  15. Morphology of thermal oxide layers on GaAs

    NASA Astrophysics Data System (ADS)

    Beserman, R.; Schwarz, S. A.; Hwang, D. M.; Chen, C. Y.

    1991-08-01

    The oxidation process of pure GaAs has been studied with use of several complementary experimental techniques: Raman scattering, electrical conductivity, transmission electron microscopy, and secondary-ion mass spectrometry. The morphology of the oxide layer and the oxide-GaAs interface evolve as a function of oxidation time. A high density of well-oriented As microcrystallites penetrates into the substrate, forming a conductive interfacial layer in the early stages of the oxidation process. After longer oxidation times, when the Raman As intensity and the interfacial conductivity are reduced, As is distributed into the oxide layer, forming crystallites that are no longer well oriented. Simultaneously, the crystalline gallium oxide breaks up to into microcrystallites that could provide channels for the outdiffusion of As. From the experimental evidence, we deduce that the interfacial density of crystalline As is reduced for long oxidation times.

  16. Simultaneous spin-coating and solvent annealing: Manipulating the active layer morphology to a power conversion efficiency of 9.6% in polymer solar cells

    DOE PAGES

    He, Zhicai; Liu, Feng; Wang, Cheng; Chen, Jihua; He, Lilin; Nordlund, Dennis; Wu, Hongbin; Russell, Thomas P.; Cao, Yong

    2015-08-20

    Here, we developed a simultaneous spin-coating/solvent-annealing process and demonstrated morphology optimization for PTB7 based organic photovoltaics. This novel processing method enhances the edge-on crystalline content in thin films and induces the formation of weak PCBM aggregates. As a result, the efficiency of polymer solar cells increased from 9.2% to a certified high efficiency of 9.61%, owing to an enhanced short-circuit current (Jsc, 18.4 mA cm–2vs. 17. 5 mA cm–2) and an improved fill factor.

  17. Simultaneous spin-coating and solvent annealing: Manipulating the active layer morphology to a power conversion efficiency of 9.6% in polymer solar cells

    SciTech Connect

    He, Zhicai; Liu, Feng; Wang, Cheng; Chen, Jihua; He, Lilin; Nordlund, Dennis; Wu, Hongbin; Russell, Thomas P.; Cao, Yong

    2015-08-20

    Here, we developed a simultaneous spin-coating/solvent-annealing process and demonstrated morphology optimization for PTB7 based organic photovoltaics. This novel processing method enhances the edge-on crystalline content in thin films and induces the formation of weak PCBM aggregates. As a result, the efficiency of polymer solar cells increased from 9.2% to a certified high efficiency of 9.61%, owing to an enhanced short-circuit current (Jsc, 18.4 mA cm–2vs. 17. 5 mA cm–2) and an improved fill factor.

  18. Surface morphological evolution during annealing of epitaxial Cu(001) layers

    SciTech Connect

    Purswani, J. M.; Gall, D.

    2008-08-15

    Single crystal Cu(001) layers were grown on MgO(001) by ultrahigh vacuum magnetron sputtering at T{sub s}=100 deg. C. Quantitative surface morphological analyses by in situ scanning tunneling microscopy show that the surfaces exhibit self-affine mound structures with a scaling exponent of 0.82{+-}0.03 and a mound radius r{sub c} that increases from 31{+-}8 to 39{+-}6 nm for increasing layer thickness t=24-120 nm. In situ annealing at 200 and 300 deg. C leads to a thermodynamically driven mass transport that minimizes the surface step density, resulting in broader mounds and a smaller root mean square surface roughness {sigma}. This effect is most pronounced for t=24 nm, for which r{sub c} increases from 31{+-}8 to 70{+-}20 nm and {sigma} decreases from 1.3{+-}0.1 to 0.74{+-}0.08 nm, resulting in a decrease in the average surface slope from {chi}=7 deg. to 2 deg. and an increase in the average terrace width w{sub T} by more than a factor of 4. In contrast, w{sub T} increases by only 20% for t=120 nm. This remarkable difference between 'thin' and 'thick' layers is attributed to diverging surface morphological pathways during annealing: The strong smoothening for t=24 nm is due to a competitive coalescence process where some mounds grow laterally at the expense of their smaller neighbors, which die out. In contrast, the initially wider mounds of thicker layers (t=120 nm) combine to form a quasistable surface morphology that exhibits anisotropic mound structures, which limit mass transport and stabilize the surface step density.

  19. Crack layer morphology and toughness characterization in steels

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.; Bessendorf, M.

    1983-01-01

    Both the macro studies of crack layer propagation are presented. The crack extension resistance parameter R sub 1 based on the morphological study of microdefects is introduced. Experimental study of the history dependent nature of G sub c supports the representation of G sub c as a product of specific enthalpy of damage (material constant) and R sub 1. The latter accounts for the history dependence. The observation of nonmonotonic crack growth under monotonic changes of J as well as statistical features of the critical energy release rate (variance of G sub c) indicate the validity of the proposed damage characterization.

  20. Surface morphological evolution of epitaxial CrN(001) layers

    SciTech Connect

    Frederick, J.R.; Gall, D.

    2005-09-01

    CrN layers, 57 and 230 nm thick, were grown on MgO(001) at T{sub s}=600-800 deg. C by ultrahigh-vacuum magnetron sputter deposition in pure N{sub 2} discharges from an oblique deposition angle {alpha}=80 deg. . Layers grown at 600 deg. C nucleate as single crystals with a cube-on-cube epitaxial relationship with the substrate. However, rough surfaces with cauliflower-type morphologies cause the nucleation of misoriented CrN grains that develop into cone-shaped grains that protrude out of the epitaxial matrix to form triangular faceted surface mounds. The surface morphology of epitaxial CrN(001) grown at 700 deg. C is characterized by dendritic ridge patterns extending along the orthogonal <110> directions superposed by square-shaped super mounds with <100> edges. The ridge patterns are attributed to a Bales-Zangwill instability while the supermounds form due to atomic shadowing which leads to the formation of epitaxial inverted pyramids that are separated from the surrounding layer by tilted nanovoids. Growth at 800 deg. C yields complete single crystals with smooth surfaces. The root-mean-square surface roughness for 230-nm-thick layers decreases from 18.8 to 9.3 to 1.1 nm as T{sub s} is raised from 600 to 700 to 800 deg. C. This steep decrease is due to a transition in the roughening mechanism from atomic shadowing to kinetic roughening. Atomic shadowing is dominant at 600 and 700 deg. C, where misoriented grains and supermounds, respectively, capture a larger fraction of the oblique deposition flux in comparison to the surrounding epitaxial matrix, resulting in a high roughening rate that is described by a power law with an exponent {beta}>0.5. In contrast, kinetic roughening controls the surface morphology for T{sub s}=800 deg. C, as well as the epitaxial fraction of the layers grown at 600 and 700 deg. C, yielding relatively smooth surfaces and {beta}{<=}0.27.

  1. Structural complexities in the active layers of organic electronics.

    PubMed

    Lee, Stephanie S; Loo, Yueh-Lin

    2010-01-01

    The field of organic electronics has progressed rapidly in recent years. However, understanding the direct structure-function relationships between the morphology in electrically active layers and the performance of devices composed of these materials has proven difficult. The morphology of active layers in organic electronics is inherently complex, with heterogeneities existing across multiple length scales, from subnanometer to micron and millimeter range. A major challenge still facing the organic electronics community is understanding how the morphology across all of the length scales in active layers collectively determines the device performance of organic electronics. In this review we highlight experiments that have contributed to the elucidation of structure-function relationships in organic electronics and also point to areas in which knowledge of such relationships is still lacking. Such knowledge will lead to the ability to select active materials on the basis of their inherent properties for the fabrication of devices with prespecified characteristics.

  2. Surface morphology and Raman spectroscopy of thin layers of antimony and bismuth chalcogenides

    NASA Astrophysics Data System (ADS)

    Luk'yanova, L. N.; Bibik, A. Yu.; Aseev, V. A.; Usov, O. A.; Makarenko, I. V.; Petrov, V. N.; Nikonorov, N. V.; Kutasov, V. A.

    2016-07-01

    The phonon spectra in thin layers of bismuth telluride and solid solutions of Bi2- x Sb x Te3- y Se y of different composition, belonging to three-dimensional topological insulators, have been investigated by micro-Raman spectroscopy, and the morphology of an interlayer van der Waals (0001) surface in them has been studied by semicontact atomic force microscopy at room temperature. The analysis of the Raman spectra and the intensity ratio of active and inactive longitudinal optical modes depending on the composition, morphology of the interlayer surface, and thickness of the layers enabled the estimation of the effect of topological surface states of Dirac fermions, associated with the strengthening of the electron-phonon interaction as a result of resonance Raman scattering, and the identification of the compositions, in which the contribution of topological surface states becomes dominant.

  3. Morphology and atomic-scale structure of single-layer WS2 nanoclusters.

    PubMed

    Füchtbauer, Henrik G; Tuxen, Anders K; Moses, Poul G; Topsøe, Henrik; Besenbacher, Flemming; Lauritsen, Jeppe V

    2013-10-14

    Two-dimensional sheets of transition metal (Mo and W) sulfides are attracting strong attention due to the unique electronic and optical properties associated with the material in its single-layer form. The single-layer MoS2 and WS2 are already in widespread commercial use in catalytic applications as both hydrotreating and hydrocracking catalysts. Consequently, characterization of the morphology and atomic structure of such particles is of utmost importance for the understanding of the catalytic active phase. However, in comparison with the related MoS2 system only little is known about the fundamental properties of single-layer WS2 (tungstenite). Here, we use an interplay of atom-resolved Scanning Tunneling Microscopy (STM) studies of Au(111)-supported WS2 nanoparticles and calculated edge structures using Density Functional Theory (DFT) to reveal the equilibrium morphology and prevalent edge structures of single-layer WS2. The STM results reveal that the single layer S-W-S sheets adopt a triangular equilibrium shape under the sulfiding conditions of the synthesis, with fully sulfided edges. The predominant edge structures are determined to be the (101[combining macron]0) W-edge, but for the smallest nanoclusters also the (1[combining macron]010) S-edges become important. DFT calculations are used to construct phase diagrams of the WS2 edges, and describe their sulfur and hydrogen coordination under different conditions, and in this way shed light on the catalytic role of WS2 edges.

  4. Swelling and morphology of the skin layer of polyamide composite membranes: an atomic force microscopy study.

    PubMed

    Freger, Viatcheslav

    2004-06-01

    The paper introduces a new methodology for studying polyamide composite membranes for reverse osmosis (RO) and nanofiltration (NF) in liquid environments. The methodology is based on atomic force microscopy of the active layer, which had been separated from the support and placed on a solid substrate. The approach was employed to determine the thickness, interfacial morphology, and dimensional changes in solution (swelling) of polyamide films. The face (active) and back (facing the support) surfaces of the RO films appeared morphologically similar, in agreement with the recently proposed model of skin formation. Measured thickness and swelling data in conjunction with the intrinsic permeability of the membranes suggest that the selective barrier in RO membrane constitutes only a fraction of the polyamide skin, whereas NF membranes behave as nearly uniform films. For NF membranes, there was reasonable correlation between the changes in the swelling and in the permeability of the membrane and the salinity and pH of the feed.

  5. Morphology and dynamics of the upper cloud layer of Venus.

    PubMed

    Markiewicz, W J; Titov, D V; Limaye, S S; Keller, H U; Ignatiev, N; Jaumann, R; Thomas, N; Michalik, H; Moissl, R; Russo, P

    2007-11-29

    Venus is completely covered by a thick cloud layer, of which the upper part is composed of sulphuric acid and some unknown aerosols. The cloud tops are in fast retrograde rotation (super-rotation), but the factors responsible for this super-rotation are unknown. Here we report observations of Venus with the Venus Monitoring Camera on board the Venus Express spacecraft. We investigate both global and small-scale properties of the clouds, their temporal and latitudinal variations, and derive wind velocities. The southern polar region is highly variable and can change dramatically on timescales as short as one day, perhaps arising from the injection of SO2 into the mesosphere. The convective cells in the vicinity of the subsolar point are much smaller than previously inferred, which we interpret as indicating that they are confined to the upper cloud layer, contrary to previous conclusions, but consistent with more recent study.

  6. Molecular layer interneurons of the cerebellum: developmental and morphological aspects.

    PubMed

    Sotelo, Constantino

    2015-10-01

    During the past 25 years, our knowledge on the development of basket and stellate cells (molecular layer interneurons [MLIs]) has completely changed, not only regarding their origin from the ventricular zone, corresponding to the primitive cerebellar neuroepithelium, instead of the external granular layer, but above all by providing an almost complete account of the genetic regulations (transcription factors and other genes) involved in their differentiation and synaptogenesis. Moreover, it has been shown that MLIs' precursors (dividing neuroblasts) and not young postmitotic neurons, as in other germinal neuroepithelia, leave the germinative zone and migrate all along a complex and lengthy path throughout the presumptive cerebellar white matter, which provides suitable niches exerting epigenetic influences on their ultimate neuronal identities. Recent studies carried out on the anatomical-functional properties of adult MLIs emphasize the importance of these interneurons in regulating PC inhibition, and point out the crucial role played by electrical synaptic transmission between MLIs as well as ephaptic interactions between them and Purkinje cells at the pinceaux level, in the regulation of this inhibition.

  7. Hydrothermal regimes of the dry active layer

    NASA Astrophysics Data System (ADS)

    Ishikawa, Mamoru; Zhang, Yinsheng; Kadota, Tsutomu; Ohata, Tetsuo

    2006-04-01

    Evaporation and condensation in the soil column clearly influence year-round nonconductive heat transfer dynamics in the dry active layer underlying semiarid permafrost regions. We deduced this from heat flux components quantified using state-of-the-art micrometeorological data sets obtained in dry and moist summers and in winters with various snow cover depths. Vapor moves easily through large pores, some of which connect to the atmosphere, allowing (1) considerable active layer warming driven by pipe-like snowmelt infiltration, and (2) direct vapor linkage between atmosphere and deeper soils. Because of strong adhesive forces, water in the dry active layer evaporates with great difficulty. The fraction of latent heat to total soil heat storage ranged from 26 to 45% in dry and moist summers, respectively. These values are not negligible, despite being smaller than those of arctic wet active layer, in which only freezing and thawing were considered.

  8. Hybrid layer thickness and morphology: Influence of cavity preparation with air abrasion.

    PubMed

    Barceleiro, Marcos Oliveira; de Mello, Jose Benedicto; Porto, Celso Luis de Angelis; Dias, Katia Regina Hostilio Cervantes; de Miranda, Mauro Sayao

    2011-01-01

    Dentinal surfaces prepared with air abrasion have considerably different characteristics from those prepared with conventional instruments. Different hybrid layer morphology and thickness occur, which can result in differences in the quality of restorations placed on dentinal surfaces prepared with a diamond bur compared to surfaces prepared using air abrasion. The objective of this study was to compare the hybrid layer thickness and morphology formed utilizing Scotchbond Multi-Purpose Plus (SBMP) on dentin prepared with a diamond bur in a high-speed handpiece and on dentin prepared using air abrasion. Flat dentin surfaces obtained from five human teeth were prepared using each method, then treated with the dentin adhesive system according to manufacturer's instructions. After a layer of composite was applied, specimens were sectioned, flattened, polished, and prepared for scanning electron microscopy. Ten different measurements of hybrid layer thickness were obtained along the bonded surface in each specimen. SBMP produced a 3.43 ± 0.75 µm hybrid layer in dentin prepared with diamond bur. This hybrid layer was regular and found consistently. In the air abrasion group, SBMP produced a 4.94 ± 1.28 µm hybrid layer, which was regular and found consistently. Statistical ANOVA (P = 0.05) indicated that there was a statistically significant difference between the groups. These data indicate that the air abrasion, within the parameters used in this study, provides a thick hybrid layer formation.

  9. Hybrid layer thickness and morphology: Influence of cavity preparation with air abrasion.

    PubMed

    Barceleiro, Marcos Oliveira; de Mello, Jose Benedicto; Porto, Celso Luis de Angelis; Dias, Katia Regina Hostilio Cervantes; de Miranda, Mauro Sayao

    2011-01-01

    Dentinal surfaces prepared with air abrasion have considerably different characteristics from those prepared with conventional instruments. Different hybrid layer morphology and thickness occur, which can result in differences in the quality of restorations placed on dentinal surfaces prepared with a diamond bur compared to surfaces prepared using air abrasion. The objective of this study was to compare the hybrid layer thickness and morphology formed utilizing Scotchbond Multi-Purpose Plus (SBMP) on dentin prepared with a diamond bur in a high-speed handpiece and on dentin prepared using air abrasion. Flat dentin surfaces obtained from five human teeth were prepared using each method, then treated with the dentin adhesive system according to manufacturer's instructions. After a layer of composite was applied, specimens were sectioned, flattened, polished, and prepared for scanning electron microscopy. Ten different measurements of hybrid layer thickness were obtained along the bonded surface in each specimen. SBMP produced a 3.43 ± 0.75 µm hybrid layer in dentin prepared with diamond bur. This hybrid layer was regular and found consistently. In the air abrasion group, SBMP produced a 4.94 ± 1.28 µm hybrid layer, which was regular and found consistently. Statistical ANOVA (P = 0.05) indicated that there was a statistically significant difference between the groups. These data indicate that the air abrasion, within the parameters used in this study, provides a thick hybrid layer formation. PMID:22313931

  10. Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

    SciTech Connect

    Abbott, Robert; Knox, Hunter Anne; James, Stephanie; Lee, Rebekah; Cole, Chris

    2016-01-01

    We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.

  11. Layer-by-layer nanoencapsulation of camptothecin with improved activity.

    PubMed

    Parekh, Gaurav; Pattekari, Pravin; Joshi, Chaitanya; Shutava, Tatsiana; DeCoster, Mark; Levchenko, Tatyana; Torchilin, Vladimir; Lvov, Yuri

    2014-04-25

    160 nm nanocapsules containing up to 60% of camptothecin in the core and 7-8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-l-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell. PMID:24508806

  12. Layer-by-layer nanoencapsulation of camptothecin with improved activity

    PubMed Central

    Parekh, Gaurav; Pattekari, Pravin; Joshi, Chaitanya; Shutava, Tatsiana; DeCoster, Mark; Levchenko, Tatyana; Torchilin, Vladimir; Lvov, Yuri

    2014-01-01

    160 nm nanocapsules containing up to 60% of camptothecin in the core and 7–8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-L-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell. PMID:24508806

  13. Morphological and optical data of AgNW embedded transparent conductive layer.

    PubMed

    Kim, Hong-Sik; Patel, Dipal B; Patel, Malkeshkumar; Kim, Joondong

    2016-12-01

    In this data article, morphological and optical data of AgNW encapsulated between ITO layers are presented to get insights into our article (DOI:10.1016/j.solmat.2016.04.038; Hong-Sik Kim, Pankaj Yadav, Malkeshkumar Patel, Hyunki Kim, Kavita Pandey, Joondong Kim, 2016) [1]. SEM images for the formation of AgNWs networks by number of spin coating are also presented. SEM photographs showing the surface morphologies before and after rapid thermal treatment of prepared samples have been presented. Apart from morphological data set, optical characteristics of this type of samples are given. The comparison plots of optical reflectance from AgNW encapsulated between ITO layers and bare ITO are given between the wavelength ranges from 300 to 1100 nm. At the end, transmittance and reflectance curves of native glass substrates used in this study are presented. PMID:27656670

  14. Characteristics of colored passive layers on titanium: morphology, optical properties, and corrosion resistance.

    PubMed

    Holmberg, Rebecca J; Beauchemin, Diane; Jerkiewicz, Gregory

    2014-12-10

    Electrochemically formed colored passive layers on titanium and their optical, surface morphology, and corrosion properties are presented and discussed. With the application of progressively higher AC voltages (VAC) during preparation of these passive layers, they are found to become more protective of the underlying metal, as determined from corrosion resistance measurements employing electrochemical polarization curve and inductively coupled plasma mass spectrometry experiments. The passive layers on titanium were found to be uniform in their surface morphology with no apparent cracks or pits. Surface morphology, and its relation to optical properties, was also investigated using visible light microscopy, profilometry, and near-infrared ultraviolet visible reflectance spectroscopy measurements. A correlation between the light reflected from the entire sample surface and the coloration of surface grains was also observed through these measurements. The reflectance spectra showed a red-shift of wavelength maxima (λmax) values as AC voltages and, therefore, thicknesses were increased. Overall, these passive layers are protective of an already remarkable metal, and with greater knowledge of the properties of colored protective layers, their potential may be employed in a wide range of applications. PMID:25401285

  15. Characteristics of colored passive layers on titanium: morphology, optical properties, and corrosion resistance.

    PubMed

    Holmberg, Rebecca J; Beauchemin, Diane; Jerkiewicz, Gregory

    2014-12-10

    Electrochemically formed colored passive layers on titanium and their optical, surface morphology, and corrosion properties are presented and discussed. With the application of progressively higher AC voltages (VAC) during preparation of these passive layers, they are found to become more protective of the underlying metal, as determined from corrosion resistance measurements employing electrochemical polarization curve and inductively coupled plasma mass spectrometry experiments. The passive layers on titanium were found to be uniform in their surface morphology with no apparent cracks or pits. Surface morphology, and its relation to optical properties, was also investigated using visible light microscopy, profilometry, and near-infrared ultraviolet visible reflectance spectroscopy measurements. A correlation between the light reflected from the entire sample surface and the coloration of surface grains was also observed through these measurements. The reflectance spectra showed a red-shift of wavelength maxima (λmax) values as AC voltages and, therefore, thicknesses were increased. Overall, these passive layers are protective of an already remarkable metal, and with greater knowledge of the properties of colored protective layers, their potential may be employed in a wide range of applications.

  16. Bisphenol A affects placental layers morphology and angiogenesis during early pregnancy phase in mice.

    PubMed

    Tait, Sabrina; Tassinari, Roberta; Maranghi, Francesca; Mantovani, Alberto

    2015-11-01

    Bisphenol A (BPA) is a widespread endocrine disrupter mainly used in food contact plastics. Much evidence supports the adverse effects of BPA, particularly on susceptible groups such as pregnant women. The present study considered placental development - relevant for pregnancy outcomes and fetal nutrition/programming - as a potential target of BPA. Pregnant CD-1 mice were administered per os with vehicle, 0.5 (BPA05) or 50 mg kg(-1) (BPA50) body weight day(-1) of BPA, from gestational day (GD) 1 to GD11. At GD12, BPA50 induced significant degeneration and necrosis of giant cells, increased vacuolization in the junctional zone in the absence of glycogen accumulation and reduction of the spongiotrophoblast layer. In addition, BPA05 induced glycogen depletion as well as significant nuclear accumulation of β-catenin in trophoblasts of labyrinthine and spongiotrophoblast layers, supporting the activation of the Wnt/β-catenin pathway. Transcriptomic analysis indicated that BPA05 promoted and BPA50 inhibited blood vessel development and branching; morphologically, maternal vessels were narrower in BPA05 placentas, whereas embryonic and maternal vessels were irregularly dilated in the labyrinth of BPA50 placentas. Quantitative polymerase chain reaction evidenced an estrogen receptor β induction by BPA50, which did not correspond to downstream genes activation; indeed, the transcription factor binding sites analysis supported the AhR/Arnt complex as regulator of BPA50-modulated genes. Conversely, Creb appeared as the main transcription factor regulating BPA05-modulated genes. Embryonic structures (head, forelimb) showed divergent perturbations upon BPA05 or BPA50 exposure, potentially related to unbalanced embryonic nutrition and/or to modulation of genes involved in embryo development. Our findings support placenta as an important target of BPA, even at environmentally relevant dose levels. PMID:26063408

  17. Morphology and wettability of ZnO nanostructures prepared by hydrothermal method on various buffer layers

    NASA Astrophysics Data System (ADS)

    Li, Bao-jia; Huang, Li-jing; Zhou, Ming; Ren, Nai-fei

    2013-12-01

    Zinc oxide (ZnO) nanostructures were prepared by hydrothermal method on glass substrates with various buffer layers: Ag, Al, aluminum-doped zinc oxide (AZO) and tin-doped indium oxide (ITO). The structure, morphology and wettability of the ZnO nanostructured surfaces were investigated by using X-ray diffraction, scanning electron microscopy and water contact angle (WCA) analysis methods, respectively. All the nanostructures grown on glass with various buffer layers exhibited strong growth orientation along the (1 0 1) plane. The nature of the buffer layer was found to have remarkable effect on the morphology and wettability of the ZnO nanostructures. Whether the buffer layers were hydrophilic or low hydrophobic, all the ZnO nanostructures grown on the various buffer layers showed high hydrophobic property, and that grown on the AZO buffer layer even exhibited superhydrophobicity with a WCA of 151.1°. This work may provide a scientific basis for self-cleaning ZnO-based optoelectronic device applications.

  18. Morphology of Organically-Modified Layered Silicates (ols) in Binary Solvents: Model System for Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Vaia, Richard; Farmer, Barry; Lui, Weidong; Bharadwaj, Rishi

    2001-03-01

    Critical to forwarding nanocomposite technology is development of a detailed understanding of the spatial distribution of the various constituents (inorganic, polymeric and additives) and associated influence on thermodynamic and kinetic (rheological) aspects of the system. With regard to these issues, in-situ small angle x-ray scattering, associated scattering models, coarse grain simulations, and rheology have been used to examine the phase behavior of organically modified layered silicates (OLS) suspended in pure and binary solvent mixtures. These serve as model systems for examining aspects of morphology development and phase behavior in thermoset and thermoplastic nanocomposites. The phase structure of solvent - OLS system is qualitatively described by Onsager arguments modified to include a crystal-solvate (intercalated phase) and a gelation point. Ternary behavior (binary solvent mixtures) provides evidence for preferential segregation of the polar component to the inorganic surface. The chemical structure of the organic surfactant modifier has a negligible influence on the structure of the intercalated phase, but has a marked effect on the extent and concentration of the dispersed phase. These studies provide insight into the use of polar activators for organosilicate rheolgical control agents and additives to enhance nanocomposite formation (e.g. H20 addition for optimal exfoliated PDMS nanocomposites and incorporation of malic anhydride to produce polypropylene nanocomposites).

  19. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    SciTech Connect

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-15

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed. - Graphical abstract: Dependence of ZnAl LDH Morphology on SDS concentration. Highlights: Black-Right-Pointing-Pointer In-situ intercalation of SDS in ZnAl LDH was achieved via urea hydrolysis method. Black-Right-Pointing-Pointer Morphology of ZnAl LDH intercalated with SDS depended on the SDS concentration. Black-Right-Pointing-Pointer Ring like morphology for SDS intercalated ZnAl LDH was obtained for the first time. Black-Right-Pointing-Pointer Growth mechanism was discussed. Black-Right-Pointing-Pointer Template assisted growth of ZnAl LDH was proposed.

  20. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    NASA Astrophysics Data System (ADS)

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-01

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed.

  1. Polymer-layered silicate nanocomposite materials: Morphological studies and potential applications

    NASA Astrophysics Data System (ADS)

    Kurian, Mary

    Polymer-layered silicate nanocomposites, materials where layered silicates are molecularly dispersed in suitable polymer matrices, are of both scientific and commercial significance. The dramatic enhancements in tensile strength, heat and solvent resistance, as well as the decrease in gas permeability of the neat polymer matrix that can be achieved through the incorporation of small amounts of a suitable layered silicate are intricately linked to the nanocomposite morphology. In the current work, the morphological behavior of nanocomposite materials has been investigated by the fabrication and extensive characterization of a series of model experimental systems. The results from the experimental systems that were developed based on one of the theoretical models for morphology prediction in nanocomposites, provide useful insight into controlling nanocomposite morphology by tailoring various system parameters. The unique properties of nanocomposites also make them promising materials for use as electrolytes in lithium polymer batteries. Though an all-solid-state lithium polymer battery is attractive due to characteristics such as low safety risks in comparison with the conventional systems that contain liquid electrolytes, several challenges related to materials design have to be overcome in order to create materials that have good mechanical properties. Our work focuses on the development of a new class of nanocomposite electrolytes where the incorporation of lithium cation-exchanged nanoscale clay sheets into a suitable polymer matrix is expected to impart the inherent favorable characteristics of nanocomposites to the electrolyte. Additionally, this modification is expected to substantially eliminate the need for lithium salt dopants that are currently used to achieve significant conductivities and form what are essentially single-ion conductors. Extensive characterization of these electrolytes showed that properties were strongly dependent on nanocomposite

  2. Morphological instability of Ag films caused by phase transition in the underlying Ta barrier layer

    SciTech Connect

    Mardani, Shabnam Vallin, Örjan; Wätjen, Jörn Timo; Norström, Hans; Olsson, Jörgen; Zhang, Shi-Li

    2014-08-18

    Wide-bandgap (WBG) semiconductor technologies are maturing and may provide increased device performance in many fields of applications, such as high-temperature electronics. However, there are still issues regarding the stability and reliability of WBG devices. Of particular importance is the high-temperature stability of interconnects for electronic systems based on WBG-semiconductors. For metallization without proper encapsulation, morphological degradation can occur at elevated temperatures. Sandwiching Ag films between Ta and/or TaN layers in this study is found to be electrically and morphologically stabilize the Ag metallization up to 800 °C, compared to 600 °C for uncapped films. However, the barrier layer plays a key role and TaN is found to be superior to Ta, resulting in the best achieved stability, whereas the difference between Ta and TaN caps is negligible. The β-to-α phase transition in the underlying Ta barrier layer is identified as the major cause responsible for the morphological instability observed above 600 °C. It is shown that this phase transition can be avoided using a stacked Ta/TaN barrier.

  3. Morphological Characteristics of Electrophysiologically Characterized Layer Vb Pyramidal Cells in Rat Barrel Cortex

    PubMed Central

    Loucif, Alexandre J. C.; Schubert, Dirk; Möck, Martin

    2016-01-01

    Layer Vb pyramidal cells are the major output neurons of the neocortex and transmit the outcome of cortical columnar signal processing to distant target areas. At the same time they contribute to local tactile information processing by emitting recurrent axonal collaterals into the columnar microcircuitry. It is, however, not known how exactly the two types of pyramidal cells, called slender-tufted and thick-tufted, contribute to the local circuitry. Here, we investigated in the rat barrel cortex the detailed quantitative morphology of biocytin-filled layer Vb pyramidal cells in vitro, which were characterized for their intrinsic electrophysiology with special emphasis on their action potential firing pattern. Since we stained the same slices for cytochrome oxidase, we could also perform layer- and column-related analyses. Our results suggest that in layer Vb the unambiguous action potential firing patterns "regular spiking (RS)" and "repetitive burst spiking (RB)" (previously called intrinsically burst spiking) correlate well with a distinct morphology. RS pyramidal cells are somatodendritically of the slender-tufted type and possess numerous local intralaminar and intracolumnar axonal collaterals, mostly reaching layer I. By contrast, their transcolumnar projections are less well developed. The RB pyramidal cells are somatodendritically of the thick-tufted type and show only relatively sparse local axonal collaterals, which are preferentially emitted as long horizontal or oblique infragranular collaterals. However, contrary to many previous slice studies, a substantial number of these neurons also showed axonal collaterals reaching layer I. Thus, electrophysiologically defined pyramidal cells of layer Vb show an input and output pattern which suggests RS cells to be more "locally segregating" signal processors whereas RB cells seem to act more on a "global integrative" scale. PMID:27706253

  4. Global morphology of ionospheric F-layer scintillations using FS3/COSMIC GPS radio occultation data

    NASA Astrophysics Data System (ADS)

    Tsai, Lung-Chih; Su, Shin-Yi

    2016-07-01

    The FormoSat-3/ Constellation Observing System for Meteorology, Ionosphere and Climate (FS3/COSMIC) has been proven a successful mission on profiling and modeling of ionospheric electron density by the radio occultation (RO) technique. In this study we report FS3/COSMIC limb-viewing observations of the GPS L-band scintillation since mid 2006 and propose to study F-layer irregularity morphology. Generally the FS3/COSMIC has performed >1000 ionospheric RO observations per day. Most of these observations can provide limb-viewing profiles of S4 scintillation index at dual L-band frequencies. There are a few percentage of FS3/COSMIC RO observations having >0.08 S4 values on average. However, seven identified areas at Central Pacific Area (-20∘~ 20∘dip latitude, 160∘E~130∘W), South American Area (-20∘~ 20∘dip latitude, 100∘W~30∘W), African Area (-20∘~ 20∘dip latitude, 30∘W~50∘E), European Area (30∘~55∘N, 0∘~55∘E), Japan See Area (35∘~55∘N, 120∘~150∘E), Arctic Area (> 65∘dip latitude), and Antarctic Area (< -65∘dip latitude) have been designated to have much higher percentage of strong L-band RO scintillation. During these years in most of the last sunspot cycle from mid 2006 to end 2014 the climatology of scintillations, namely, its variations with each identified area, season, local time, magnetic activity and solar activity have been documented.

  5. Morphological architecture of dual-layer hollow fiber for membrane distillation with higher desalination performance.

    PubMed

    Wang, Peng; Teoh, May May; Chung, Tai-Shung

    2011-11-01

    A new strategy to enhance the desalination performance of polyvinylidene fluoride (PVDF) hollow fiber membrane for membrane distillation (MD) via architecture of morphological characteristics is explored in this study. It is proposed that a dual-layer hollow fiber consisting of a fully finger-like macrovoid inner-layer and a sponge-like outer-layer may effectively enhance the permeation flux while maintaining the wetting resistance. Dual-layer fibers with the proposed morphology have been fabricated by the dry-jet wet spinning process via careful choice of dopes composition and coagulation conditions. In addition to high energy efficiency (EE) of 94%, a superior flux of 98.6 L m(-2) h(-1) is obtained during the direct contact membrane distillation (DCMD) desalination experiments. Moreover, the liquid entry pressure (LEP) and long-term DCMD performance test show high wetting resistance and long-term stability. Mathematical modeling has been conducted to investigate the membrane mass transfer properties in terms of temperature profile and apparent diffusivity of the membranes. It is concluded that the enhancement in permeation flux arises from the coupling effect of two mechanisms; namely, a higher driving force and a lower mass transfer resistance, while the later is the major contribution. This work provides an insight on MD fundamentals and strategy to tailor making ideal membranes for DCMD application in desalination industry.

  6. Fine control of perovskite-layered morphology and composition via sequential deposition crystallization process towards improved perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Luo, Yi; Meng, Fanli; Zhao, Erfei; Zheng, Yan-Zhen; Zhou, Yali; Tao, Xia

    2016-04-01

    The ability to prepare high coverage and compact perovskite films via solution-based crystallization manipulation processes still represents a vital issue towards improving the ultimate photoelectric conversion efficiency of devices. In this work, we prepare the active perovskite layer by means of sequential deposition crystallization process i.e. dipping PbI2-infiltrated TiO2 film within CH3NH3I solution from 20s to 60s. The morphology and thickness of the as-prepared perovskite layer, and its overall performance superiority are investigated. X-ray diffraction (XRD) reveals that a maximum conversion of PbI2 to perovskite is completed upon applying a sequential deposition crystallization process of 40s. Field emission scanning electron microscope (FESEM) demonstrates that the coverage of the perovskite capping layer exhibits a trend from rise to decline in the whole dipping time from 20s to 60s. By fine control of the dipping time, a 620 nm-thickness compact perovskite active layer is obtained at the optimized dipping time of 40s and is verified to possess strong light absorption and high electron extraction efficiency, leading to a higher photocurrent. By further optimizing the mesoporous TiO2 film thickness, a high photocurrent of 23.98 mA cm-2 and an efficiency of 13.47% are achieved.

  7. Sensitivity of mesoscale model urban boundary layer meteorology to urban morphology

    NASA Astrophysics Data System (ADS)

    Flagg, D. D.; Taylor, P. A.

    2010-11-01

    Mesoscale modeling of the urban boundary layer requires careful parameterization of the surface due to its heterogeneous morphology. Model estimated meteorological quantities, including the surface energy budget and canopy layer variables, will respond accordingly to the scale of representation. This study examines the sensitivity of the surface energy balance, canopy layer and boundary layer meteorology to the scale of urban surface representation in a real urban area (Detroit-Windsor (USA-Canada)) during several dry, cloud-free summer periods. The model used is the Weather Research and Forecasting (WRF) model with its coupled single-layer urban canopy model. Some model verification is presented using measurements from the Border Air Quality and Meteorology Study (BAQS-Met) 2007 field campaign and additional sources. Case studies span from "neighborhood" (10 s ~ 30 m) to very coarse (120 s ~ 3.7 km) resolution. Small changes in scale can affect the classification of the surface, affecting both the local and grid-average meteorology. Results indicate high sensitivity in turbulent latent heat flux from the natural surface and sensible heat flux from the urban canopy. Small scale change is also shown to delay timing of a lake-breeze front passage and can affect the timing of local transition in static stability.

  8. Isolation of tissue layers in hermatypic corals by N-acetylcysteine: morphological and proteomic examinations

    NASA Astrophysics Data System (ADS)

    Peng, S.-E.; Luo, Y.-J.; Huang, H.-J.; Lee, I.-T.; Hou, L.-S.; Chen, W.-N. U.; Fang, L.-S.; Chen, C.-S.

    2008-03-01

    Corals are diploblastic in body pattern and include two tissue layers, the epidermis and gastrodermis, interconnected by an acellular matrix mesoglea. During development, cells in these tissue layers differentiate morphologically and functionally. In most hermatypic corals, the gastrodermis further develops an ability to associate with microalgae dinoflagellates. This endosymbiosis occurs inside specific host gastrodermal cells, and its mechanism still remains unclear notwithstanding decades of research. The delay in progress is partly due to the difficulty in separating the gastrodermis and its symbionts from the epidermis for detailed cellular and biochemical investigations. The present study reports a simple method to separate these two tissue layers in hermatypic corals using the reducing agent, N-acetylcysteine (NAC). Efficient tissue and proteomic isolations are demonstrated by microscopy and two-dimensional SDS polyacrylamide gel electrophoresis (2D SDS-PAGE). The NAC treatment was able to separate tissue layers without inducing protein degradation. Furthermore, the sensitivity of protein detection greatly increases in the isolated tissue layers. The application of the present technique provides future research on endosymbiosis and coral development with a tool for higher accuracy and sensitivity.

  9. Morphological/Chemical Imaging of Demineralized Dentin Layer in Its Natural, Wet State

    PubMed Central

    Wang, Yong; Yao, Xiaomei

    2010-01-01

    Objective Measuring the structure, composition or suitability for bonding of the acid etched dentin substrate, especially in its hydrated state, has been a formidable problem. The purpose of this study was to determine the morphological and structural profiles of the dentin demineralized layer measured in its natural wet state using environmental scanning electron microscopy (ESEM) and micro-Raman imaging. Materials and methods The occlusal 1/3 of the crown was removed from 9 extracted, unerupted human third molars. Dentin surfaces were abraded with 600 grit SiC sandpaper under water to create smear layers. The prepared dentin surfaces were randomly selected for treatment with the self-etching agent (Adper™ Prompt L-Pop) or the total etching agent 35% H3PO4 gel (with/without agitation). Micro-Raman spectra and imaging were acquired at 1-1.5 μm spatial resolution at positions perpendicular to the treated surfaces; since this technique is non-destructive, the same specimens were also imaged with ESEM. Specimens were kept wet throughout spectral acquisition and ESEM observations. Results ESEM could be used to reveal demineralized layers in acid-etched dentin, but the resolution was low and no collagen fibrils were disclosed. The detailed chemical maps/profiles of demineralized dentin layers under wet conditions could be obtained using Raman imaging. It was shown that the mineral existed in the superficial layer of all etched dentin covered with smear layers. The mineral was much easier to be removed underneath the superficial layer. The depth, degree, and profile of dentin demineralization were dependent on the types of acids (self-etching vs. total etching) and application procedures (with vs. without agitation). Significance Most current adhesives are applied using wet bonding techniques in which the dentin is kept fully hydrated throughout the bonding. Our ability to fully characterize the hydrated, etched dentin substrates is very important for understanding

  10. Electronic Structure and Morphology of Graphene Layers on SiC

    NASA Astrophysics Data System (ADS)

    Ohta, Taisuke

    2008-03-01

    Recent years have witnessed the discovery and the unique electronic properties of graphene, a sheet of carbon atoms arranged in a honeycomb lattice. The unique linear dispersion relation of charge carriers near the Fermi level (``Dirac Fermions'') lead to exciting transport properties, such as an unusual quantum Hall effect, and have aroused scientific and technological interests. On the way towards graphene-based electronics, a knowledge of the electronic band structure and the morphology of epitaxial graphene films on silicon carbide substrates is imperative. We have studied the evolution of the occupied band structure and the morphology of graphene layers on silicon carbide by systematically increasing the layer thickness. Using angle-resolved photoemission spectroscopy (ARPES), we examine this unique 2D system in its development from single layer to multilayers, by characteristic changes in the π band, the highest occupied state, and the dispersion relation in the out-of-plane electron wave vector in particular. The evolution of the film morphology is evaluated by the combination of low-energy electron microscopy and ARPES. By exploiting the sensitivity of graphene's electronic states to the charge carrier concentration, changes in the on-site Coulomb potential leading to a change of π and π* bands can be examined using ARPES. We demonstrate that, in a graphene bilayer, the gap between π and π* bands can be controlled by selectively adjusting relative carrier concentrations, which suggests a possible application of the graphene bilayer for switching functions in electronic devices. This work was done in collaboration with A. Bostwick, J. L. McChesney, and E. Rotenberg at Advanced Light Source, Lawrence Berkeley National Laboratory, K. Horn at Fritz-Haber-Institut, K. V. Emtsev and Th. Seyller at Lehrstuhl für Technische Physik, Universität Erlangen-Nürnberg, and F. El Gabaly and A. K. Schmid at National Center for Electron Microscopy, Lawrence Berkeley

  11. Morphology and Mineralogy of Libya Montes Layered Delta Deposits, Mars: Implications for Long-Term Aqueous Alteration

    NASA Astrophysics Data System (ADS)

    Erkeling, G.; Reiss, D.; Poulet, F.; Carter, J.; Loizeau, D.; Hiesinger, H.; Ivanov, M. A.; Hauber, E.; Jaumann, R.

    2011-03-01

    We present the first results of our morphologic and mineralogic investigation of layered delta-deposits in the Libya Montes, where our observations suggest long-term availability of water and aqueous alteration.

  12. Current-driven morphological evolution of single-layer epitaxial islands on crystalline substrates

    NASA Astrophysics Data System (ADS)

    Dasgupta, Dwaipayan; Sfyris, Georgios I.; Maroudas, Dimitrios

    2013-12-01

    We develop and validate a nonlinear model for the current-driven dynamics of single-layer epitaxial islands on crystalline substrates. Simulations based on the model show that the dependence of the stable steady island migration speed vm on the inverse of the island size is not linear for larger-than-critical island sizes. In this nonlinear regime, we report morphological transitions, Hopf bifurcations, and instabilities for various surface crystallographic orientations and island misfit strains. Proper rescaling of vm gives a universal linear relationship for its dependence on island size.

  13. Morphological and electrophysiological properties of atypically oriented layer 2 pyramidal cells of the juvenile rat neocortex.

    PubMed

    van Brederode, J F; Foehring, R C; Spain, W J

    2000-01-01

    We used whole-cell patch clamp recordings combined with intracellular dye-filling to examine the morphological and electrophysiological properties of atypically oriented pyramidal cells located at the layer 1/2 border of the juvenile rat neocortex. Orientation of the apical dendrite varied from oblique (>20 degrees from vertical) to truly horizontal (90 degrees from vertical). The length of the apical dendrite ranged from 150 to 400 microm. The total horizontal domain of the dendritic tree (including basal dendrites) of the longest horizontal pyramids exceeded 500 microm, but we also found short horizontal cells with horizontal dendritic domains of less than 300 microm. In addition, atypically oriented pyramids had long horizontal axon collaterals in layer 1/2. Electrophysiologically, atypically oriented pyramidal cells had intrinsic membrane properties similar to regularly oriented pyramids that have been described in the superficial layers at this age in the rat. Cells that fired repetitively were all regular spiking. In addition, we identified a subgroup of neurons (20%) in this sample, which were unable to fire more than a few spikes at the beginning of the current pulse. We suggest that the unique orientation and size of their dendritic trees and the length and arrangement of their local axons collaterals make atypically oriented pyramids in layer 2 ideally suited to perform horizontal integration of synaptic inputs in the neocortex.

  14. Exploring interface morphology of a deeply buried layer in periodic multilayer

    NASA Astrophysics Data System (ADS)

    Das, Gangadhar; Khooha, Ajay; Singh, A. K.; Srivastava, A. K.; Tiwari, M. K.

    2016-06-01

    Long-term durability of a thin film device is strongly correlated with the nature of interface structure associated between different constituent layers. Synthetic periodic multilayer structures are primarily employed as artificial X-ray Bragg reflectors in many applications, and their reflection efficiency is predominantly dictated by the nature of the buried interfaces between the different layers. Herein, we demonstrate the applicability of the combined analysis approach of the X-ray reflectivity and grazing incidence X-ray fluorescence measurements for the reliable and precise determination of a buried interface structure inside periodic X-ray multilayer structures. X-ray standing wave field (XSW) generated under Bragg reflection condition is used to probe the different constituent layers of the W- B4C multilayer structure at 10 keV and 12 keV incident X-ray energies. Our results show that the XSW assisted fluorescence measurements are markedly sensitive to the location and interface morphology of a buried layer structure inside a periodic multilayer structure. The cross sectional transmission electron microscopy results obtained on the W-B4C multilayer structure provide a deeper look on the overall reliability and accuracy of the XSW method. The method described here would also be applicable for nondestructive characterization of a wide range of thin film based semiconductor and optical devices.

  15. Neuronal firing sensitivity to morphologic and active membrane parameters.

    PubMed

    Weaver, Christina M; Wearne, Susan L

    2008-01-01

    Both the excitability of a neuron's membrane, driven by active ion channels, and dendritic morphology contribute to neuronal firing dynamics, but the relative importance and interactions between these features remain poorly understood. Recent modeling studies have shown that different combinations of active conductances can evoke similar firing patterns, but have neglected how morphology might contribute to homeostasis. Parameterizing the morphology of a cylindrical dendrite, we introduce a novel application of mathematical sensitivity analysis that quantifies how dendritic length, diameter, and surface area influence neuronal firing, and compares these effects directly against those of active parameters. The method was applied to a model of neurons from goldfish Area II. These neurons exhibit, and likely contribute to, persistent activity in eye velocity storage, a simple model of working memory. We introduce sensitivity landscapes, defined by local sensitivity analyses of firing rate and gain to each parameter, performed globally across the parameter space. Principal directions over which sensitivity to all parameters varied most revealed intrinsic currents that most controlled model output. We found domains where different groups of parameters had the highest sensitivities, suggesting that interactions within each group shaped firing behaviors within each specific domain. Application of our method, and its characterization of which models were sensitive to general morphologic features, will lead to advances in understanding how realistic morphology participates in functional homeostasis. Significantly, we can predict which active conductances, and how many of them, will compensate for a given age- or development-related structural change, or will offset a morphologic perturbation resulting from trauma or neurodegenerative disorder, to restore normal function. Our method can be adapted to analyze any computational model. Thus, sensitivity landscapes, and the

  16. Morphological modelling of three-phase microstructures of anode layers using SEM images.

    PubMed

    Abdallah, Bassam; Willot, François; Jeulin, Dominique

    2016-07-01

    A general method is proposed to model 3D microstructures representative of three-phases anode layers used in fuel cells. The models are based on SEM images of cells with varying morphologies. The materials are first characterized using three morphological measurements: (cross-)covariances, granulometry and linear erosion. They are measured on segmented SEM images, for each of the three phases. Second, a generic model for three-phases materials is proposed. The model is based on two independent underlying random sets which are otherwise arbitrary. The validity of this model is verified using the cross-covariance functions of the various phases. In a third step, several types of Boolean random sets and plurigaussian models are considered for the unknown underlying random sets. Overall, good agreement is found between the SEM images and three-phases models based on plurigaussian random sets, for all morphological measurements considered in the present work: covariances, granulometry and linear erosion. The spatial distribution and shapes of the phases produced by the plurigaussian model are visually very close to the real material. Furthermore, the proposed models require no numerical optimization and are straightforward to generate using the covariance functions measured on the SEM images.

  17. Effect of ZnO seed layer on the morphology and optical properties of ZnO nanorods grown on GaN buffer layers

    SciTech Connect

    Nandi, R. Mohan, S. Major, S. S.; Srinivasa, R. S.

    2014-04-24

    ZnO nanorods were grown by chemical bath deposition on sputtered, polycrystalline GaN buffer layers with and without ZnO seed layer. Scanning electron microscopy and X-ray diffraction show that the ZnO nanorods on GaN buffer layers are not vertically well aligned. Photoluminescence spectrum of ZnO nanorods grown on GaN buffer layer, however exhibits a much stronger near-band-edge emission and negligible defect emission, compared to the nanorods grown on ZnO buffer layer. These features are attributed to gallium incorporation at the ZnO-GaN interface. The introduction of a thin (25 nm) ZnO seed layer on GaN buffer layer significantly improves the morphology and vertical alignment of ZnO-NRs without sacrificing the high optical quality of ZnO nanorods on GaN buffer layer. The presence of a thick (200 nm) ZnO seed layer completely masks the effect of the underlying GaN buffer layer on the morphology and optical properties of nanorods.

  18. Surface morphology of molecular-beam epitaxially grown Si(1-x)Ge(x) layers on (100) and (110) Si

    NASA Technical Reports Server (NTRS)

    Pike, W. T.; Fathauer, R. W.; Anderson, M. S.

    1992-01-01

    The surface morphology and dislocation structure of Si(1-x)Ge(x) layers grown on (100) and (110) Si substrates have been investigated using atomic force microscopy, and scanning and transmission electron microscopy. The layers, which have up to a 1.2 percent lattice mismatch with the substrates, were grown by molecular-beam epitaxy at 550 C at thicknesses above those required for the introduction of dislocations. Si(1-x)Ge(x) layers grown on (100) show a crosshatch morphology which is correlated to the underlying misfit dislocation network. Annealing greatly enhances the surface roughness producing a partial islanding growing on the preexisting crosshatch morphology. On the (110) substrates no annealing is necessary to produce a roughened surface. The roughened surface morphology is analyzed as a strain-reducing growth mode which enables partial relaxation of the near-surface atomic planes.

  19. Melanin as an active layer in biosensors

    SciTech Connect

    Piacenti da Silva, Marina Congiu, Mirko Oliveira Graeff, Carlos Frederico de; Fernandes, Jéssica Colnaghi Biziak de Figueiredo, Natália Mulato, Marcelo

    2014-03-15

    The development of pH sensors is of great interest due to its extensive application in several areas such as industrial processes, biochemistry and particularly medical diagnostics. In this study, the pH sensing properties of an extended gate field effect transistor (EGFET) based on melanin thin films as active layer are investigated and the physical mechanisms related to the device operation are discussed. Thin films were produced from different melanin precursors on indium tin oxide (ITO) and gold substrates and were investigated by Atomic Force Microscopy and Electrochemical Impedance Spectroscopy. Experiments were performed in the pH range from 2 to 12. EGFETs with melanin deposited on ITO and on gold substrates showed sensitivities ranging from 31.3 mV/pH to 48.9 mV/pH, depending on the melanin precursor and the substrate used. The pH detection is associated with specific binding sites in its structure, hydroxyl groups and quinone imine.

  20. Dynamics of active layer in wooded palsas of northern Quebec

    NASA Astrophysics Data System (ADS)

    Jean, Mélanie; Payette, Serge

    2014-02-01

    Palsas are organic or mineral soil mounds having a permafrost core. Palsas are widespread in the circumpolar discontinuous permafrost zone. The annual dynamics and evolution of the active layer, which is the uppermost layer over the permafrost table and subjected to the annual freeze-thaw cycle, are influenced by organic layer thickness, snow depth, vegetation type, topography and exposure. This study examines the influence of vegetation types, with an emphasis on forest cover, on active layer dynamics of palsas in the Boniface River watershed (57°45‧ N, 76°00‧ W). In this area, palsas are often colonized by black spruce trees (Picea mariana (Mill.) B.S.P.). Thaw depth and active layer thickness were monitored on 11 wooded or non-wooded mineral and organic palsas in 2009, 2010 and 2011. Snow depth, organic layer thickness, and vegetation types were assessed. The mapping of a palsa covered by various vegetation types and a large range of organic layer thickness were used to identify the factors influencing the spatial patterns of thaw depth and active layer. The active layer was thinner and the thaw rate slower in wooded palsas, whereas it was the opposite in more exposed sites such as forest openings, shrubs and bare ground. Thicker organic layers were associated with thinner active layers and slower thaw rates. Snow depth was not an important factor influencing active layer dynamics. The topography of the mapped palsa was uneven, and the environmental factors such as organic layer, snow depth, and vegetation types were heterogeneously distributed. These factors explain a part of the spatial variation of the active layer. Over the 3-year long study, the area of one studied palsa decreased by 70%. In a context of widespread permafrost decay, increasing our understanding of factors that influence the dynamics of wooded and non-wooded palsas and understanding of the role of vegetation cover will help to define the response of discontinuous permafrost landforms

  1. Structure, composition and morphology of bioactive titanate layer on porous titanium surfaces

    NASA Astrophysics Data System (ADS)

    Li, Jinshan; Wang, Xiaohua; Hu, Rui; Kou, Hongchao

    2014-07-01

    A bioactive coating was produced on pore surfaces of porous titanium samples by an amendatory alkali-heat treatment method. Porous titanium was prepared by powder metallurgy and its porosity and average size were 45% and 135 μm, respectively. Coating morphology, coating structure and phase constituents were examined by SEM, XPS and XRD. It was found that a micro-network structure with sizes of <200 nm mainly composed of bioactive sodium titanate and rutile phases of TiO2 covered the interior and exterior of porous titanium cells, and redundant Ca ion was detected in the titanate layer. The concentration distribution of Ti, O, Ca and Na in the coating showed a compositional gradient from the intermediate layer toward the outer surface. These compositional gradients indicate that the coating bonded to Ti substrate without a distinct interface. After immersion into the SBF solution for 3 days, a bone-like carbonate-hydroxylapatite showing a good biocompatibility was detected on the coating surface. And the redundant Ca advanced the bioactivity of the coating. Thus, the present modification is expected to allow the use of the bioactive porous titanium as artificial bones even under load-bearing conditions.

  2. Seasonal activity and morphological changes in martian gullies

    USGS Publications Warehouse

    Dundas, Colin M.; Diniega, Serina; Hansen, Candice J.; Byrne, Shane; McEwen, Alfred S.

    2012-01-01

    Recent studies of martian dune and non-dune gullies have suggested a seasonal control on present-day gully activity. The timing of current gully activity, especially activity involving the formation or modification of channels (which commonly have been taken as evidence of fluvial processes), has important implications regarding likely gully formation processes and necessary environmental conditions. In this study, we describe the results of frequent meter-scale monitoring of several active gully sites by the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). The aim is to better assess the scope and nature of current morphological changes and to provide improved constraints on timing of gully activity on both dune and non-dune slopes. Our observations indicate that (1) gully formation on Mars is ongoing today and (2) the most significant morphological changes are strongly associated with seasonal frost and defrosting activity. Observed changes include formation of all major components of typical gully landforms, although we have not observed alcove formation in coherent bedrock. These results reduce the need to invoke recent climate change or present-day groundwater seepage to explain the many martian gullies with pristine appearance.

  3. Two types of positive disturbances in the daytime mid-latitude F2-layer: Morphology and formation mechanisms

    NASA Astrophysics Data System (ADS)

    Mikhailov, A. V.; Perrone, L.; Smirnova, N. V.

    2012-06-01

    Morphological analysis of foF2 variations for the periods of daytime positive disturbances over three ionospheric stations St. Petersburg (sub-auroral zone), Slough (middle latitudes), and Alma-Ata (middle-low latitudes) has confirmed the existence of two types of positive F2-layer disturbances with different morphology. Type I is referred to those followed by quiet or positively disturbed ionospheric conditions. They occur under low or moderate level of geomagnetic activity. Positive disturbances of type II are related to strong geomagnetic storms and they are followed by negative ionospheric disturbances. The two types manifest different occurrence frequency distribution and its dependence on latitude and level of geomagnetic activity. They also exhibit different duration and magnitude. This tells that two types of disturbances belong to different classes of events and may have different formation mechanisms. Millstone Hill ISR and digisonde hmF2 and foF2 observations for some selected periods of F2-layer positive disturbances of both types were analyzed. The original earlier developed self-consistent method to extract thermospheric parameters from ISR observations was used to estimate the contribution of various aeronomic parameters to the observed storm time F2-layer variations. Our analysis of a well-pronounced positive disturbances of type II on December 14, 2006 has confirmed the well-known concept by Prölss (1993a,b, 1995)—daytime midlatitude positive disturbances of type II are mainly produced by TADs and following them disturbed equatorward winds. However our calculations have shown that about half of the observed positive storm effect may be attributed to thermospheric parameter (neutral composition and temperature) variations. The type II of positive disturbances presents the first phase of a two-phase (positive/negative) ionospheric storm. For this reason their occurrence frequency distribution is similar to that for negative disturbances. The

  4. Thin-Layer Chromatography: Four Simple Activities for Undergraduate Students.

    ERIC Educational Resources Information Center

    Anwar, Jamil; And Others

    1996-01-01

    Presents activities that can be used to introduce thin-layer chromatography at the undergraduate level in relatively less developed countries and that can be performed with very simple and commonly available apparati in high schools and colleges. Activities include thin-layer chromatography with a test-tube, capillary feeder, burette, and rotating…

  5. Sporadic E-Layers and Meteor Activity

    NASA Astrophysics Data System (ADS)

    Alimov, Obid

    2016-07-01

    In average width it is difficult to explain variety of particularities of the behavior sporadic layer Es ionospheres without attraction long-lived metallic ion of the meteoric origin. Mass spectrometric measurements of ion composition using rockets indicate the presence of metal ions Fe+, Mg+, Si+, Na+, Ca+, K+, Al+ and others in the E-region of the ionosphere. The most common are the ions Fe+, Mg+, Si+, which are primarily concentrated in the narrow sporadic layers of the ionosphere at altitudes of 90-130 km. The entry of meteoric matter into the Earth's atmosphere is a source of meteor atoms (M) and ions (M +) that later, together with wind shear, produce midlatitude sporadic Es layer of the ionosphere. To establish the link between sporadic Es layer and meteoroid streams, we proceeded from the dependence of the ionization coefficient of meteors b on the velocity of meteor particles in different meteoroid streams. We investigated the dependence of the critical frequency f0Es of sporadic E on the particle velocity V of meteor streams and associations. It was established that the average values of f0Es are directly proportional to the velocity V of meteor streams and associations, with the correlation coefficient of 0.53 < R < 0.74. Thus, the critical frequency of the sporadic layer Es increases with the increase of particle velocity V in meteor streams, which indicates the direct influence of meteor particles on ionization of the lower ionosphere and formation of long-lived metal atoms M and ions M+ of meteoric origin.

  6. Silver ions/ovalbumin films layer-by-layer self-assembled polyacrylonitrile nanofibrous mats and their antibacterial activity.

    PubMed

    Song, Rukun; Yan, Jinjiao; Xu, Shasha; Wang, Yuntao; Ye, Ting; Chang, Jing; Deng, Hongbing; Li, Bin

    2013-08-01

    The CN groups of polyacrylonitrile (PAN) can strongly adsorb silver ions. The possibility of using this attraction as a layer-by-layer (LBL) self-assembly driving force was investigated. Firstly, the surface of the PAN nanofibrous mats was modified by silver ions to make sure it was positively charged. Then oppositely charged ovalbumin (OVA) and silver ions in aqueous media were alternatively deposited onto the surface of the obtained composite mats by layer-by-layer self-assembly technique. The morphology of the LBL films coating mats was observed by field emission scanning electron microscope (FE-SEM). The deposition of silver ions and OVA was confirmed by X-ray photoelectron spectroscopy (XPS) and wide-angle X-ray diffraction (XRD). The thermal degradation properties were investigated by thermo-gravimetric analysis (TGA). Besides these, the cytotoxicity and antibacterial activity of the prepared mats were studied via flow cytometry (FCM) and inhibition zone test, respectively. The results showed that the composite mats after LBL self-assembly processing exhibited improved thermal stability, slightly decreased cytotoxicity, and excellent antibacterial activity against Escherichia coil and Staphylococcus aureus. PMID:23563300

  7. Interaction Forces and Morphology of a Protein-Resistant Poly(ethylene glycol) Layer

    PubMed Central

    Heuberger, M.; Drobek, T.; Spencer, N. D.

    2005-01-01

    The molecular interactions on a protein-resistant surface coated with low-molecular-weight poly(ethylene glycol) (PEG) copolymer brushes are investigated using the extended surface forces apparatus. The observed interaction force is predominantly repulsive and nearly elastic. The chains are extended with respect to the Flory radius, which is in agreement with qualitative predictions of scaling theory. Comparison with theory allows the determination of relevant quantities such as brush length and adsorbed mass. Based on these results, we propose a molecular model for the adsorbed copolymer morphology. Surface-force isotherms measured at high resolution allow distinctive structural forces to be detected, suggesting the existence of a weak equilibrium network between poly(ethylene glycol) and water—a finding in accordance with the remarkable solution properties of PEG. The occurrence of a fine structure is interpreted as a water-induced restriction of the polymer's conformational space. This restriction is highly relevant for the phenomenon of PEG protein resistance. Protein adsorption requires conformational transitions, both in the protein as well as in the PEG layer, which are energetically and kinetically unfavorable. PMID:15501935

  8. Cross-linked hybrid nanofiltration membrane with antibiofouling properties and self-assembled layered morphology.

    PubMed

    Singh, Ajay K; Prakash, S; Kulshrestha, Vaibhav; Shahi, Vinod K

    2012-03-01

    A new siloxane monomer, 3-(3-(diethoxy(2-(5-(4-(10-ethoxy-4-hydroxy-2,2-dimethyl-11-oxa-2-ammonio-6-aza-10-silatridecan-10-yl)phenyl)-1,3,4-oxadi azol-2-ylthio)ethyl)silyl)propylamino)-2-hydroxy-N,N,N-trimethylpropan-1-aminium chloride (OA), was synthesized by reported 3-((4-(5-(2-((3-aminopropyl) diethoxysilyl)ethylthio)-1,3,4-oxadiazol-2-yl)phenyl) diethoxysilyl)propan-1-amine (APDSMO) and glycidyltrimethylammonium chloride (GDTMAC) by epoxide ring-opening reaction. OA-poly(vinyl alcohol) (PVA) hybrid antibiofouling nanofilter (NF) membranes were prepared by acid-catalyzed sol-gel followed by formal cross-linking. Membranes showed wormlike arrangement and self-assembled layered morphology with varying OA content. Hybrid NF membrane, especially OA-6, showed low surface roughness, high hydrophilic nature, low biofouling, high cross-linking density, thermal and mechanical stablility, solvent- and chlorine-tolerant nature, along with good permeability and salt rejection. Prepared OA-6 hybrid NF membrane can be used efficiently for desalting and purification of water with about 2.0 g/L salt content (groundwater in major part of India). The described method provides novel route for producing antibiofouling membranes of diversified applications. PMID:22360398

  9. Morphology and physiology of excitatory neurons in layer 6b of the somatosensory rat barrel cortex.

    PubMed

    Marx, Manuel; Feldmeyer, Dirk

    2013-12-01

    Neocortical lamina 6B (L6B) is a largely unexplored layer with a very heterogeneous cellular composition. To date, only little is known about L6B neurons on a systematic and quantitative basis. We investigated the morphological and electrophysiological properties of excitatory L6B neurons in the rat somatosensory barrel cortex using whole-cell patch-clamp recordings and simultaneous biocytin fillings. Subsequent histological processing and computer-assisted 3D reconstructions provided the basis for a classification of excitatory L6B neurons according to their structural and functional characteristics. Three distinct clusters of excitatory L6B neurons were identified: (C1) pyramidal neurons with an apical dendrite pointing towards the pial surface, (C2) neurons with a prominent, "apical"-like dendrite not oriented towards the pia, and (C3) multipolar spiny neurons without any preferential dendritic orientation. The second group could be further subdivided into three categories termed inverted, "tangentially" oriented and "horizontally" oriented neurons. Furthermore, based on the axonal domain two subcategories of L6B pyramidal cells were identified that had either a more barrel-column confined or an extended axonal field. The classification of excitatory L6B neurons provided here may serve as a basis for future studies on the structure, function, and synaptic connectivity of L6B neurons.

  10. A study on the morphology and catalytic activity of gold nanoparticles by the kinetic Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    He, Xiang; Chen, Zhao-Xu

    2016-05-01

    We studied the thermal-stability of supported Au nanoparticles on the substrates of different binding strength to gold by Monte Carlo simulations. It has been revealed that the stable Au morphology is determined by the temperature and the binding strength. When heated on the strongly-binding substrates, the Au nanoparticles would wet the substrate completely and form monolayer. The stable Au layered structure of few layers can be formed by the incomplete wetting of clusters on the intermediate-binding substrates. The simulation results are in good agreement with pertinent experimental and theoretical results. Based on the simulation results and experimental observations, we find the strong linkage between the top edge sites and the activity TOF of low-temperature CO oxidation. We conclude that the top edges sites of Au layered structures are possible reactive sites. This study may provide new perspective for controlling morphology and understanding catalytic activity of supported metallic clusters.

  11. Effect of Morphology Control of Light Absorbing Layer on CH3NH3PbI3 Perovskite Solar Cells.

    PubMed

    Lei, Binglong; Eze, Vincent Obiozo; Mori, Tatsuo

    2016-04-01

    As one of the most significant components of perovskite solar cells, the perovskite light absorbing layer demands high quality to guarantee extraordinary power conversion efficiency (PCE). We have fabricated series of CH3NH3PbI3 perovskite solar cells by virtue of gas-flowing assisting (GFA), spin coating twice for the Pbl2 layer and dipping the semi-samples in a thermal CH3NH3I solution, by which some undesirable perovskite morphologies can be effectively avoided. The modified conductions have also dramatically improved the perovskite layer and elevated the coverage ratio from 53.6% to 79.5%. All the fabrication processes, except the steps for deposition of the hole transport material (HTM) and back gold electrode, have been conducted in air and an average PCE of 6.6% has been achieved by initiatively applying N,N'-bis(1-naphtyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) doped by MoO3 as HTM. The CH3NH3PbI3 perovskite's morphology and its coverage ratio to the underneath TiO2 mesoporic layer are evaluated to account for the cells' performance. It has demonstrated that higher homogeneity and coverage ratio of the CH3NH3PbI3 layer have most significantly contributed to the solar cells' light conversion efficiency. Keywords: Perovskite, Solar Cell, Morphology, Coverage Ratio, Hole Transport Material. PMID:27451600

  12. Observing the morphology of single-layered embedded silicon nanocrystals by using temperature-stable TEM membranes

    PubMed Central

    Hiller, Daniel; Laube, Jan; Zacharias, Margit; Kübel, Christian

    2015-01-01

    Summary We use high-temperature-stable silicon nitride membranes to investigate single layers of silicon nanocrystal ensembles by energy filtered transmission electron microscopy. The silicon nanocrystals are prepared from the precipitation of a silicon-rich oxynitride layer sandwiched between two SiO2 diffusion barriers and subjected to a high-temperature annealing. We find that such single layers are very sensitive to the annealing parameters and may lead to a significant loss of excess silicon. In addition, these ultrathin layers suffer from significant electron beam damage that needs to be minimized in order to image the pristine sample morphology. Finally we demonstrate how the silicon nanocrystal size distribution develops from a broad to a narrow log-normal distribution, when the initial precipitation layer thickness and stoichiometry are below a critical value. PMID:25977867

  13. Observing the morphology of single-layered embedded silicon nanocrystals by using temperature-stable TEM membranes.

    PubMed

    Gutsch, Sebastian; Hiller, Daniel; Laube, Jan; Zacharias, Margit; Kübel, Christian

    2015-01-01

    We use high-temperature-stable silicon nitride membranes to investigate single layers of silicon nanocrystal ensembles by energy filtered transmission electron microscopy. The silicon nanocrystals are prepared from the precipitation of a silicon-rich oxynitride layer sandwiched between two SiO2 diffusion barriers and subjected to a high-temperature annealing. We find that such single layers are very sensitive to the annealing parameters and may lead to a significant loss of excess silicon. In addition, these ultrathin layers suffer from significant electron beam damage that needs to be minimized in order to image the pristine sample morphology. Finally we demonstrate how the silicon nanocrystal size distribution develops from a broad to a narrow log-normal distribution, when the initial precipitation layer thickness and stoichiometry are below a critical value. PMID:25977867

  14. Absence of the granular layer and keratohyalin define a morphologically distinct subset of individuals with ichthyosis vulgaris.

    PubMed

    Fleckman, Philip; Brumbaugh, Steven

    2002-08-01

    The clinical diagnosis of ichthyosis vulgaris (IV) can be difficult. Abnormalities in the granular layer and the ultrastructure of keratohyalin granules (KHG) suggest that morphology may be helpful. To clarify morphologic findings in IV, 41 clinically affected individuals and 21 unaffected family members or age- and sex-matched controls were studied by light microscopy. In these, the granular layer was totally absent in approximately 50% of affected individuals, while present in all controls. Forty-seven individuals in the light microscopy group were also studied by electron microscopy. Keratohyalin granules were absent in all affected individuals lacking the granular layer by light microscopy. Clinical severity usually correlated with the lack of a granular layer and KHG. Absence of the granular layer was consistent in different anatomic sites and in serial biopsies taken over a 1-3-year period. In a subset of clinically affected, unrelated subjects with moderate to severe involvement, four out of 11 (36%) had similar findings. Keratinocytes cultured from affected individuals with no KHG expressed virtually no detectable profilaggrin protein in vitro. The data suggest that a subset of individuals with moderate to severe IV have a consistently absent granular layer and KHG. Absence of the granular layer and lack of KHG correlated almost perfectly; thus light microscopy offers a convenient means of identifying this subtype of IV. However, both morphologic types of IV were observed within single families. Therefore, the relationship between granular layer abnormalities and IV is complex and requires the study of more affected families. One interpretation of the data is that IV is a multigenic disorder in which one of the genes alters profilaggrin expression. We propose this clinical and histologic phenotype as useful for identifying the gene(s) involved and also for determining whether it represents a modifier or a major locus of the disorder.

  15. Pore morphology: a vital factor in determining electrochemical properties of electrical double layer capacitors.

    PubMed

    Liang, Yeru; Li, Zhenghui; Yang, Xiaoqing; Fu, Ruowen; Wu, Dingcai

    2013-11-01

    The ordered 2D reverse hexagonal pore morphology facilitates rapid ion diffusion more than the disordered wormhole-like pore morphology, thus leading to superior electrochemical properties such as rate capabilities.

  16. Active unjamming of confluent cell layers

    NASA Astrophysics Data System (ADS)

    Marchetti, M. Cristina

    Cell motion inside dense tissues governs many biological processes, including embryonic development and cancer metastasis, and recent experiments suggest that these tissues exhibit collective glassy behavior. Motivated by these observations, we have studied a model of dense tissues that combines self-propelled particle models and vertex models of confluent cell layers. In this model, referred to as self-propelled Voronoi (SPV), cells are described as polygons in a Voronoi tessellation with directed noisy cell motility and interactions governed by a shape energy that incorporates the effects of cell volume incompressibility, contractility and cell-cell adhesion. Using this model, we have demonstrated a new density-independent solid-liquid transition in confluent tissues controlled by cell motility and a cell-shape parameter measuring the interplay of cortical tension and cell-cell adhesion. An important insight of this work is that the rigidity and dynamics of cell layers depends sensitively on cell shape. We have also used the SPV model to test a new method developed by our group to determine cellular forces and tissue stresses from experimentally accessible cell shapes and traction forces, hence providing the spatio-temporal distribution of stresses in motile dense tissues. This work was done with Dapeng Bi, Lisa Manning and Xingbo Yang. MCM was supported by NSF-DMR-1305184 and by the Simons Foundation.

  17. Atomic layer deposition of epitaxial layers of anatase on strontium titanate single crystals: Morphological and photoelectrochemical characterization

    SciTech Connect

    Kraus, Theodore J.; Nepomnyashchii, Alexander B.; Parkinson, B. A.

    2015-01-15

    Atomic layer deposition was used to grow epitaxial layers of anatase (001) TiO{sub 2} on the surface of SrTiO{sub 3} (100) crystals with a 3% lattice mismatch. The epilayers grow as anatase (001) as confirmed by x-ray diffraction. Atomic force microscope images of deposited films showed epitaxial layer-by-layer growth up to about 10 nm, whereas thicker films, of up to 32 nm, revealed the formation of 2–5 nm anatase nanocrystallites oriented in the (001) direction. The anatase epilayers were used as substrates for dye sensitization. The as received strontium titanate crystal was not sensitized with a ruthenium-based dye (N3) or a thiacyanine dye (G15); however, photocurrent from excited state electron injection from these dyes was observed when adsorbed on the anatase epilayers. These results show that highly ordered anatase surfaces can be grown on an easily obtained substrate crystal.

  18. Kinetics of Ion Transport in Perovskite Active Layers and Its Implications for Active Layer Stability.

    PubMed

    Bag, Monojit; Renna, Lawrence A; Adhikari, Ramesh Y; Karak, Supravat; Liu, Feng; Lahti, Paul M; Russell, Thomas P; Tuominen, Mark T; Venkataraman, D

    2015-10-14

    Solar cells fabricated using alkyl ammonium metal halides as light absorbers have the right combination of high power conversion efficiency and ease of fabrication to realize inexpensive but efficient thin film solar cells. However, they degrade under prolonged exposure to sunlight. Herein, we show that this degradation is quasi-reversible, and that it can be greatly lessened by simple modifications of the solar cell operating conditions. We studied perovskite devices using electrochemical impedance spectroscopy (EIS) with methylammonium (MA)-, formamidinium (FA)-, and MA(x)FA(1-x) lead triiodide as active layers. From variable temperature EIS studies, we found that the diffusion coefficient using MA ions was greater than when using FA ions. Structural studies using powder X-ray diffraction (PXRD) show that for MAPbI3 a structural change and lattice expansion occurs at device operating temperatures. On the basis of EIS and PXRD studies, we postulate that in MAPbI3 the predominant mechanism of accelerated device degradation under sunlight involves thermally activated fast ion transport coupled with a lattice-expanding phase transition, both of which are facilitated by absorption of the infrared component of the solar spectrum. Using these findings, we show that the devices show greatly improved operation lifetimes and stability under white-light emitting diodes, or under a solar simulator with an infrared cutoff filter or with cooling. PMID:26414066

  19. Electrophysiological and morphological properties of neurons in layer 5 of the rat postrhinal cortex.

    PubMed

    Sills, Joseph B; Connors, Barry W; Burwell, Rebecca D

    2012-09-01

    The postrhinal (POR) cortex of the rat is homologous to the parahippocampal cortex of the primate based on connections and other criteria. POR provides the major visual and visuospatial input to the hippocampal formation, both directly to CA1 and indirectly through connections with the medial entorhinal cortex. Although the cortical and hippocampal connections of the POR cortex are well described, the physiology of POR neurons has not been studied. Here, we examined the electrical and morphological characteristics of layer 5 neurons from POR cortex of 14- to 16-day-old rats using an in vitro slice preparation. Neurons were subjectively classified as regular-spiking (RS), fast-spiking (FS), or low-threshold spiking (LTS) based on their electrophysiological properties and similarities with neurons in other regions of neocortex. Cells stained with biocytin included pyramidal cells and interneurons with bitufted or multipolar dendritic patterns. Similarity analysis using only physiological data yielded three clusters that corresponded to FS, LTS, and RS classes. The cluster corresponding to the FS class was composed entirely of multipolar nonpyramidal cells, and the cluster corresponding to the RS class was composed entirely of pyramidal cells. The third cluster, corresponding to the LTS class, was heterogeneous and included both multipolar and bitufted dendritic arbors as well as one pyramidal cell. We did not observe any intrinsically bursting pyramidal cells, which is similar to entorhinal cortex but unlike perirhinal cortex. We conclude that POR includes at least two major classes of neocortical inhibitory interneurons, but has a functionally restricted cohort of pyramidal cells.

  20. Peptide isolated from Cry1Ab16 toxin present in Bacillus thuringiensis: Synthesis and morphology data for layer-by-layer films studied by atomic force microscopy.

    PubMed

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Gomes Vasconcelos, Andreanne; Leite, José R S A; Delerue-Matos, Cristina

    2016-09-01

    The peptide PcL342-354C was obtained from the Cry1Ab16 toxin present in Bacillus thuringiensis ("Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from B. thuringiensis AC11" (Kashyap, 2012) [1]). In this data article, we report the synthesis and characterization of the PcL342-354C peptide by MALDI-TOF/TOF mass spectrometry. In addition, the preparation of layer-by-layer films is shown based on interspersion of this peptide with both polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS), self-assembled on ITO (indium tin oxide) electrodes. The morphology of the ITO/PEI/PSS/PcL342-354C film was analyzed using atomic force microscopy (AFM). We also evaluated the effect of the number of bilayers in ITO/PEI/(PSS/PcL342-354C) n on the morphology of the film using AFM amplitude images. Further details about this study were published elsewhere, "Layer-by-layer films containing peptides of the Cry1Ab16 toxin from B. thuringiensis for potential biotechnological applications," (Plácido et al., 2016) [2]. PMID:27294178

  1. Peptide isolated from Cry1Ab16 toxin present in Bacillus thuringiensis: Synthesis and morphology data for layer-by-layer films studied by atomic force microscopy.

    PubMed

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Gomes Vasconcelos, Andreanne; Leite, José R S A; Delerue-Matos, Cristina

    2016-09-01

    The peptide PcL342-354C was obtained from the Cry1Ab16 toxin present in Bacillus thuringiensis ("Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from B. thuringiensis AC11" (Kashyap, 2012) [1]). In this data article, we report the synthesis and characterization of the PcL342-354C peptide by MALDI-TOF/TOF mass spectrometry. In addition, the preparation of layer-by-layer films is shown based on interspersion of this peptide with both polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS), self-assembled on ITO (indium tin oxide) electrodes. The morphology of the ITO/PEI/PSS/PcL342-354C film was analyzed using atomic force microscopy (AFM). We also evaluated the effect of the number of bilayers in ITO/PEI/(PSS/PcL342-354C) n on the morphology of the film using AFM amplitude images. Further details about this study were published elsewhere, "Layer-by-layer films containing peptides of the Cry1Ab16 toxin from B. thuringiensis for potential biotechnological applications," (Plácido et al., 2016) [2].

  2. Photocatalytic activity of layered perovskite-like oxides in practically valuable chemical reactions

    NASA Astrophysics Data System (ADS)

    Rodionov, I. A.; Zvereva, I. A.

    2016-03-01

    The photocatalytic properties of layered perovskite-like oxides corresponding to the Ruddlesen–Popper, Dion–Jacobson and Aurivillius phases are considered. Of the photocatalytic reactions, the focus is on the reactions of water splitting, hydrogen evolution from aqueous solutions of organic substances and degradation of model organic pollutants. Possibilities to conduct these reactions under UV and visible light in the presence of layered perovskite-like oxides and composite photocatalysts based on them are shown. The specific surface area, band gap energy, particle morphology, cation and anion doping and surface modification are considered as factors that affect the photocatalytic activity. Special attention is paid to the possibilities to enhance the photocatalytic activity by intercalation, ion exchange and exfoliation, which are inherent in this class of compounds. Conclusions are made about the prospects for the use of layered perovskite-like oxides in photocatalysis. The bibliography includes 253 references.

  3. Photocatalytic activity of layered perovskite-like oxides in practically valuable chemical reactions

    NASA Astrophysics Data System (ADS)

    Rodionov, I. A.; Zvereva, I. A.

    2016-03-01

    The photocatalytic properties of layered perovskite-like oxides corresponding to the Ruddlesen-Popper, Dion-Jacobson and Aurivillius phases are considered. Of the photocatalytic reactions, the focus is on the reactions of water splitting, hydrogen evolution from aqueous solutions of organic substances and degradation of model organic pollutants. Possibilities to conduct these reactions under UV and visible light in the presence of layered perovskite-like oxides and composite photocatalysts based on them are shown. The specific surface area, band gap energy, particle morphology, cation and anion doping and surface modification are considered as factors that affect the photocatalytic activity. Special attention is paid to the possibilities to enhance the photocatalytic activity by intercalation, ion exchange and exfoliation, which are inherent in this class of compounds. Conclusions are made about the prospects for the use of layered perovskite-like oxides in photocatalysis. The bibliography includes 253 references.

  4. Activity recognition from video using layered approach

    NASA Astrophysics Data System (ADS)

    McPherson, Charles A.; Irvine, John M.; Young, Mon; Stefanidis, Anthony

    2012-01-01

    The adversary in current threat situations can no longer be identified by what they are, but by what they are doing. This has lead to a large increase in the use of video surveillance systems for security and defense applications. With the quantity of video surveillance at the disposal of organizations responsible for protecting military and civilian lives comes issues regarding the storage and screening the data for events and activities of interest. Activity recognition from video for such applications seeks to develop automated screening of video based upon the recognition of activities of interest rather than merely the presence of specific persons or vehicle classes developed for the Cold War problem of "Find the T72 Tank". This paper explores numerous approaches to activity recognition, all of which examine heuristic, semantic, and syntactic methods based upon tokens derived from the video. The proposed architecture discussed herein uses a multi-level approach that divides the problem into three or more tiers of recognition, each employing different techniques according to their appropriateness to strengths at each tier using heuristics, syntactic recognition, and HMM's of token strings to form higher level interpretations.

  5. Mesoporous layer-by-layer ordered nanohybrids of layered double hydroxide and layered metal oxide: highly active visible light photocatalysts with improved chemical stability.

    PubMed

    Gunjakar, Jayavant L; Kim, Tae Woo; Kim, Hyo Na; Kim, In Young; Hwang, Seong-Ju

    2011-09-28

    Mesoporous layer-by-layer ordered nanohybrids highly active for visible light-induced O(2) generation are synthesized by self-assembly between oppositely charged 2D nanosheets of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) and layered titanium oxide. The layer-by-layer ordering of two kinds of 2D nanosheets is evidenced by powder X-ray diffraction and cross-sectional high resolution-transmission electron microscopy. Upon the interstratification process, the original in-plane atomic arrangements and electronic structures of the component nanosheets remain intact. The obtained heterolayered nanohybrids show a strong absorption of visible light and a remarkably depressed photoluminescence signal, indicating an effective electronic coupling between the two component nanosheets. The self-assembly between 2D inorganic nanosheets leads to the formation of highly porous stacking structure, whose porosity is controllable by changing the ratio of layered titanate/Zn-Cr-LDH. The resultant heterolayered nanohybrids are fairly active for visible light-induced O(2) generation with a rate of ∼1.18 mmol h(-1) g(-1), which is higher than the O(2) production rate (∼0.67 mmol h(-1) g(-1)) by the pristine Zn-Cr-LDH material, that is, one of the most effective visible light photocatalysts for O(2) production, under the same experimental condition. This result highlights an excellent functionality of the Zn-Cr-LDH-layered titanate nanohybrids as efficient visible light active photocatalysts. Of prime interest is that the chemical stability of the Zn-Cr-LDH is significantly improved upon the hybridization, a result of the protection of the LDH lattice by highly stable titanate layer. The present findings clearly demonstrate that the layer-by-layer-ordered assembly between inorganic 2D nanosheets is quite effective not only in improving the photocatalytic activity of the component semiconductors but also in synthesizing novel porous LDH-based hybrid materials with improved chemical

  6. Sporadic Layer es and Siesmic Activity

    NASA Astrophysics Data System (ADS)

    Alimov, Obid; Blokhin, Alexandr; Kalashnikova, Tatyana

    2016-07-01

    To determine the influence of seismogenic disturbances on the calm state of the iono-sphere and assess the impact of turbulence development in sporadic-E during earthquake prepa-ration period we calculated the variation in the range of semitransparency ∆fES = f0ES - fbES. The study was based primarily on the ionograms obtained by vertical sounding of the ionosphere at Dushanbe at nighttime station from 15 to 29 August 1986. In this time period four successive earthquakes took place, which serves the purpose of this study of the impact of seis-mogenic processes on the intensity of the continuous generation of ionospheric turbulence. Analysis of the results obtained for seismic-ionospheric effects of 1986 earthquakes at station Dushanbe has shown that disturbance of ionospheric parameters during earthquake prepa-ration period displays a pronounced maximum with a duration of t = 1-6 hours. Ionospheric effects associated with the processes of earthquake preparation emerge quite predictably, which verifies seismogenic disturbances in the ionosphere. During the preparation of strong earthquakes, ionograms of vertical sounding produced at station Dushanbe - near the epicenter area - often shown the phenomenon of spreading traces of sporadic Es. It is assumed that the duration of manifestation of seismic ionospheric precursors in Du-shanbe τ = 1 - 6 hours may be associated with deformation processes in the Earth's crust and var-ious faults, as well as dissimilar properties of the environment of the epicentral area. It has been shown that for earthquakes with 4.5 ≤ M ≤ 5.5 1-2 days prior to the event iono-spheric perturbations in the parameters of the sporadic layer Es and an increase in the value of the range of semitransparency Es - ΔfEs were observed, which could lead to turbulence at altitudes of 100-130 km.

  7. Van der Waals Layered Materials: Surface Morphology, Interlayer Interaction, and Electronic Structure

    NASA Astrophysics Data System (ADS)

    Yeh, Po-Chun

    The search for new ultrathin materials as the "new silicon" has begun. In this dissertation, I examine (1) the surface structure, including the growth, the crystal quality, and thin film surface corrugation of a monolayer sample and a few layers of MoS2 and WSe2, and (2) their electronic structure. The characteristics of these electronic systems depend intimately on the morphology of the surfaces they inhabit, and their interactions with the substrate or within layers. These physical properties will be addressed in each chapter. This thesis has dedicated to the characterization of mono- and a few layers of MoS2 and WSe2 that uses surface-sensitive probes such as low-energy electron microscopy and diffraction (LEEM and LEED). Prior to our studies, the characterization of monolayer MoS2 and WSe2 has been generally limited to optical and transport probes. Furthermore, the heavy use of thick silicon oxide layer as the supporting substrate has been important in order to allow optical microscopic characterization of the 2D material. Hence, to the best of our knowledge, this has prohibited studies of this material on other surfaces, and it has precluded the discovery of potentially rich interface interactions that may exist between MoS 2 and its supporting substrate. Thus, in our study, we use a so-called SPELEEM system (Spectroscopic Photo-Emission and Low Energy Electron Microscopy) to address these imaging modalities: (1) real-space microscopy, which would allow locating of monolayer MoS2 samples, (2) spatially-resolved low-energy diffraction which would allow confirmation of the crystalline quality and domain orientation of MoS2 samples, and, (3) spatially-resolved spectroscopy, which would allow electronic structure mapping of MoS2 samples. Moreover, we have developed a preparation procedure for samples that yield, a surface-probe ready, ultra-clean, and can be transferred on an arbitrary substrate. To fully understand the physics in MoS2 such as direct

  8. Orientation in multi-layer chitosan hydrogel: morphology, mechanism, and design principle

    PubMed Central

    Nie, Jingyi; Lu, Wentao; Ma, Jianjun; Yang, Ling; Wang, Zhengke; Qin, An; Hu, Qiaoling

    2015-01-01

    Hydrogels with organized structure have attracted remarkable attentions for bio-related applications. Among the preparation of hierarchical hydrogel materials, fabrication of hydrogel with multi-layers is an important branch. Although the generation mechanism of layers had been fully discussed, sub-layer structure was not sufficiently studied. In this research, multi-layered chitosan hydrogel with oriented structure was constructed, and the formation mechanism of orientation was proposed, based on gelation behavior and entanglement of polymer chains in the hydrogel-solution system. Employing the layered-oriented characteristic, chitosan hydrogel materials with various shapes and structure can be designed and fabricated. PMID:25559867

  9. Effects of interfacial layer wettability and thickness on the coating morphology and sirolimus release for drug-eluting stent.

    PubMed

    Bedair, Tarek M; Yu, Seung Jung; Im, Sung Gap; Park, Bang Ju; Joung, Yoon Ki; Han, Dong Keun

    2015-12-15

    Drug-eluting stents (DESs) have been used to treat coronary artery diseases by placing in the arteries. However, current DESs still suffer from polymer coating defects such as delamination and peeling-off that follows stent deployment. Such coating defects could increase the roughness of DES and might act as a source of late or very late thrombosis and might increase the incident of restenosis. In this regard, we modified the cobalt-chromium (Co-Cr) alloy surface with hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) or hydrophobic poly(2-hydroxyethyl methacrylate)-grafted-poly(caprolactone) (PHEMA-g-PCL) brushes. The resulting surfaces were biocompatible and biodegradable, which could act as anchoring layer for the drug-in-polymer matrix coating. The two modifications were characterized by ATR-FTIR, XPS, water contact angle measurements, SEM and AFM. On the control and modified Co-Cr samples, a sirolimus (SRL)-containing poly(D,L-lactide) (PDLLA) were ultrasonically spray-coated, and the drug release was examined for 8weeks under physiological conditions. The results demonstrated that PHEMA as a primer coating improved the coating stability and degradation morphology, and drug release profile for short-term as compared to control Co-Cr, but fails after 7weeks in physiological buffer. On the other hand, the hydrophobic PHEMA-g-PCL brushes not only enhanced the stability and degradation morphology of the PDLLA coating layer, but also sustained SRL release for long-term. At 8-week of release test, the surface morphologies and release profiles of coated PDLLA layers verified the beneficial effect of hydrophobic PCL brushes as well as their thickness on coating stability. Our study concludes that 200nm thickness of PHEMA-g-PCL as interfacial layer affects the stability and degradation morphology of the biodegradable coating intensively to be applied for various biodegradable-based DESs. PMID:26319336

  10. Effects of interfacial layer wettability and thickness on the coating morphology and sirolimus release for drug-eluting stent.

    PubMed

    Bedair, Tarek M; Yu, Seung Jung; Im, Sung Gap; Park, Bang Ju; Joung, Yoon Ki; Han, Dong Keun

    2015-12-15

    Drug-eluting stents (DESs) have been used to treat coronary artery diseases by placing in the arteries. However, current DESs still suffer from polymer coating defects such as delamination and peeling-off that follows stent deployment. Such coating defects could increase the roughness of DES and might act as a source of late or very late thrombosis and might increase the incident of restenosis. In this regard, we modified the cobalt-chromium (Co-Cr) alloy surface with hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) or hydrophobic poly(2-hydroxyethyl methacrylate)-grafted-poly(caprolactone) (PHEMA-g-PCL) brushes. The resulting surfaces were biocompatible and biodegradable, which could act as anchoring layer for the drug-in-polymer matrix coating. The two modifications were characterized by ATR-FTIR, XPS, water contact angle measurements, SEM and AFM. On the control and modified Co-Cr samples, a sirolimus (SRL)-containing poly(D,L-lactide) (PDLLA) were ultrasonically spray-coated, and the drug release was examined for 8weeks under physiological conditions. The results demonstrated that PHEMA as a primer coating improved the coating stability and degradation morphology, and drug release profile for short-term as compared to control Co-Cr, but fails after 7weeks in physiological buffer. On the other hand, the hydrophobic PHEMA-g-PCL brushes not only enhanced the stability and degradation morphology of the PDLLA coating layer, but also sustained SRL release for long-term. At 8-week of release test, the surface morphologies and release profiles of coated PDLLA layers verified the beneficial effect of hydrophobic PCL brushes as well as their thickness on coating stability. Our study concludes that 200nm thickness of PHEMA-g-PCL as interfacial layer affects the stability and degradation morphology of the biodegradable coating intensively to be applied for various biodegradable-based DESs.

  11. Controlling Edge Morphology in Graphene Layers Using Electron Irradiation: From Sharp Atomic Edges to Coalesced Layers Forming Loops

    SciTech Connect

    Cruz-Silva, E.; Botello-Mendez, A.R.; Barnett, Zachary M; Jia, Xiaoting; Dresselhaus, M; Terrones, H.; Terrones, M.; Sumpter, Bobby G; Meunier, Vincent

    2010-01-01

    Recent experimental reports indicate that Joule heating can atomically sharpen the edges of chemical vapor deposition grown graphitic nanoribbons. The absence or presence of loops between adjacent layers in the annealed materials is the topic of a growing debate that this Letter aims to put to rest. We offer a rationale explaining why loops do form if Joule heating is used alone, and why adjacent nanoribbon layers do not coalesce when Joule heating is applied after high-energy electrons first irradiate the sample. Our work, based on large-scale quantum molecular dynamics and electronic-transport calculations, shows that vacancies on adjacent graphene sheets, created by electron irradiation, inhibit the formation of edge loops.

  12. [Effects of water stress and nitrogen fertilization on peanut root morphological development and leaf physiological activities].

    PubMed

    Ding, Hong; Zhang, Zhi-meng; Dai, Liang-xiang; Ci, Dun-wei; Qin, Fei-fei; Song, Wen-wu; Liu, Meng-juan; Fu, Xiao

    2015-02-01

    Taking 'Huayu 22' peanut as test material, effect of soil water content and nitrogen fertilization on the leaf physiological activities and root morphological characteristics of peanut plants were analyzed. Two levels of soil water condition were: (1) well-watered condition and (2) moderate water stress, and three levels of nitrogen were: (1) none nitrogen (N0), (2) moderate nitrogen (N1, 90 kg · hm(-2)) and (3) high nitrogen (N2, 180 kg · hm(-2)). The results showed that N1 significantly increased the peanut yield under two water conditions, but showed no significant effect on harvest index compared with N0. Under water stress condition, N1 had no significant effects on total root biomass and total root length, but the total root surface area was remarkably increased. The nitrogen fertilization significantly increased the root length and root surface area in 20-40 cm soil layer, and N2 significantly increased the root biomass and root surface area in the soil layer below 40 cm. The application of nitrogen remarkably increased CAT and POD activities in leaf, while MDA content was decreased with the increase of nitrogen level. Under well-watered condition, the root biomass, root length and root surface area in the soil layer below 40 cm and total root surface area were significantly reduced by nitrogen application, however, only N1 could increase leaf protective enzyme activities. Correlation analysis showed that the root length in 20-40 cm soil layer and SOD, CAT, POD activities in leaf were highly significantly related with peanut yield. PMID:26094460

  13. [Effects of water stress and nitrogen fertilization on peanut root morphological development and leaf physiological activities].

    PubMed

    Ding, Hong; Zhang, Zhi-meng; Dai, Liang-xiang; Ci, Dun-wei; Qin, Fei-fei; Song, Wen-wu; Liu, Meng-juan; Fu, Xiao

    2015-02-01

    Taking 'Huayu 22' peanut as test material, effect of soil water content and nitrogen fertilization on the leaf physiological activities and root morphological characteristics of peanut plants were analyzed. Two levels of soil water condition were: (1) well-watered condition and (2) moderate water stress, and three levels of nitrogen were: (1) none nitrogen (N0), (2) moderate nitrogen (N1, 90 kg · hm(-2)) and (3) high nitrogen (N2, 180 kg · hm(-2)). The results showed that N1 significantly increased the peanut yield under two water conditions, but showed no significant effect on harvest index compared with N0. Under water stress condition, N1 had no significant effects on total root biomass and total root length, but the total root surface area was remarkably increased. The nitrogen fertilization significantly increased the root length and root surface area in 20-40 cm soil layer, and N2 significantly increased the root biomass and root surface area in the soil layer below 40 cm. The application of nitrogen remarkably increased CAT and POD activities in leaf, while MDA content was decreased with the increase of nitrogen level. Under well-watered condition, the root biomass, root length and root surface area in the soil layer below 40 cm and total root surface area were significantly reduced by nitrogen application, however, only N1 could increase leaf protective enzyme activities. Correlation analysis showed that the root length in 20-40 cm soil layer and SOD, CAT, POD activities in leaf were highly significantly related with peanut yield.

  14. Cardiac modeling using active appearance models and morphological operators

    NASA Astrophysics Data System (ADS)

    Pfeifer, Bernhard; Hanser, Friedrich; Seger, Michael; Hintermueller, Christoph; Modre-Osprian, Robert; Fischer, Gerald; Muehlthaler, Hannes; Trieb, Thomas; Tilg, Bernhard

    2005-04-01

    We present an approach for fast reconstructing of cardiac myocardium and blood masses of a patient's heart from morphological image data, acquired either MRI or CT, in order to estimate numerically the spread of electrical excitation in the patient's atria and ventricles. The approach can be divided into two main steps. During the first step the ventricular and atrial blood masses are extracted employing Active Appearance Models (AAM). The left and right ventricular blood masses are segmented automatically after providing the positions of the apex cordis and the base of the heart. Because of the complex geometry of the atria the segmentation process of the atrial blood masses requires more information as the ventricular blood mass segmentation process of the ventricles. We divided, for this reason, the left and right atrium into three divisions of appearance. This proved sufficient for the 2D AAM model to extract the target blood masses. The base of the heart, the left upper and left lower pulmonary vein from its first up to its last appearance in the image stack, and the right upper and lower pulmonary vein have to be marked. After separating the volume data into these divisions the 2D AAM search procedure extracts the blood masses which are the main input for the second and last step in the myocardium extraction pipeline. This step uses morphologically-based operations in order to extract the ventricular and atrial myocardium either directly by detecting the myocardium in the volume block or by reconstructing the myocardium using mean model information, in case the algorithm fails to detect the myocardium.

  15. Efficient C–C bond splitting on Pt monolayer and sub-monolayer catalysts during ethanol electro-oxidation: Pt layer strain and morphology effects

    SciTech Connect

    Loukrakpam, Rameshwori; Yuan, Qiuyi; Petkov, Valeri; Gan, Lin; Rudi, Stefan; Yang, Ruizhi; Huang, Yunhui; Brankovic, Stanko R.; Strasser, Peter

    2014-07-23

    Efficient catalytic C–C bond splitting coupled with complete 12-electron oxidation of the ethanol molecule to CO2 is reported on nanoscale electrocatalysts comprised of a Pt monolayer (ML) and sub-monolayer (sML) deposited on Au nanoparticles (Au@Pt ML/sML). The Au@Pt electrocatalysts were synthesized using surface limited redox replacement (SLRR) of an underpotentially deposited (UPD) Cu monolayer in an electrochemical cell reactor. Au@Pt ML showed improved catalytic activity for ethanol oxidation reaction (EOR) and, unlike their Pt bulk and Pt sML counterparts, was able to generate CO2 at very low electrode potentials owing to efficient C–C bond splitting. To explain this, we explore the hypothesis that competing strain effects due to the Pt layer coverage/morphology (compressive) and the Pt–Au lattice mismatch (tensile) control surface chemisorption and overall activity. Control experiments on well-defined model Pt monolayer systems are carried out involving a wide array of methods such as high-energy X-ray diffraction, pair-distribution function (PDF) analysis, in situ electrochemical FTIR spectroscopy, and in situ scanning tunneling microscopy. The vibrational fingerprints of adsorbed CO provide compelling evidence on the relation between surface bond strength, layer strain and morphology, and catalytic activity.

  16. Tremendous effect of the morphology of birnessite-type manganese oxide nanostructures on catalytic activity.

    PubMed

    Hou, Jingtao; Li, Yuanzhi; Mao, Mingyang; Ren, Lu; Zhao, Xiujian

    2014-09-10

    The octahedral layered birnessite-type manganese oxide (OL-1) with the morphologies of nanoflowers, nanowires, and nanosheets were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric/differential scanning calorimetry (TG/DSC), Brunnauer-Emmett-Teller (BET), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS). The OL-1 nanoflowers possess the highest concentration of oxygen vacancies or Mn(3+), followed by the OL-1 nanowires and nanosheets. The result of catalytic tests shows that the OL-1 nanoflowers exhibit a tremendous enhancement in the catalytic activity for benzene oxidation as compared to the OL-1 nanowires and nanosheets. Compared to the OL-1 nanosheets, the OL-1 nanoflowers demonstrate an enormous decrease (ΔT(50) = 274 °C; ΔT(90) > 248 °C) in reaction temperatures T50 and T90 (corresponding to 50 and 90% benzene conversion, respectively) for benzene oxidation. The origin of the tremendous effect of morphology on the catalytic activity for the nanostructured OL-1 catalysts is experimentally and theoretically studied via CO temperature-programmed reduction (CO-TPR) and density functional theory (DFT) calculation. The tremendous catalytic enhancement of the OL-1 nanoflowers compared to the OL-1 nanowires and nanosheets is attributed to their highest surface area as well as their highest lattice oxygen reactivity due to their higher concentration of oxygen vacancies or Mn(3+), thus tremendously improving the catalytic activity for the benzene oxidation.

  17. Double-layered ejecta craters on Mars: morphology, formation, and a comparison with the Ries ejecta blanket

    NASA Astrophysics Data System (ADS)

    Kenkmann, Thomas; Wulf, Gerwin; Sturm, Sebastian; Pietrek, Alexa

    2015-04-01

    The ejecta blankets of impact craters in volatile-rich environments often show characteristic layered ejecta morphologies. The so-called double-layer ejecta (DLE) craters are probably the most confusing crater types showing two ejecta layers with distinct morphologies. A phenomenological ejecta excavation and emplacement model for DLE craters is proposed based on a detailed case study of the Martian crater Steinheim - a textbook like, pristine DLE crater - and studies of other DLE craters [1]. The observations show that DLE craters on Mars are the result of an impact event into a rock/ice mixture that produces large amounts of shock-induced vaporization and melting of ground ice. The deposits of the ejecta curtain are wet in the distal part and dryer in composition in the proximal part. As a result, the outer ejecta layer is emplaced as medial and distal ejecta that propagate outwards in a fluid saturated debris flow mode after landing overrunning previously formed secondary craters. In contrast, the inner ejecta layer is formed by a translational slide of the proximal ejecta deposits. This slide overruns and superimposes parts of the outer ejecta layer. Basal melting of the ice components of the ejecta volumes at the transient crater rim is induced by frictional heating and the enhanced pressure at depth. The results indicate similar processes also for other planetary bodies with volatile-rich environments, such as Ganymede, Europa or the Earth. The Ries crater on Earth has a similar ejecta thickness distribution as DLE craters on Mars [2]. Here basal sliding and fluidization of the ejecta increases outward by the entrainment of locally derived Tertiary sands and clays, that are saturated with groundwater. References: [1] Wulf, G. & Kenkmann, T. (2015) Met. Planet. Sci. (in press); [2] Sturm, S., Wulf. G., Jung, D. & Kenkmann, T. (2013) Geology 41, 531-534.

  18. Role of 4-tert-Butylpyridine as a Hole Transport Layer Morphological Controller in Perovskite Solar Cells.

    PubMed

    Wang, Shen; Sina, Mahsa; Parikh, Pritesh; Uekert, Taylor; Shahbazian, Brian; Devaraj, Arun; Meng, Ying Shirley

    2016-09-14

    Hybrid organic-inorganic materials for high-efficiency, low-cost photovoltaic devices have seen rapid progress since the introduction of lead based perovskites and solid-state hole transport layers. Although majority of the materials used for perovskite solar cells (PSC) are introduced from dye-sensitized solar cells (DSSCs), the presence of a perovskite capping layer as opposed to a single dye molecule (in DSSCs) changes the interactions between the various layers in perovskite solar cells. 4-tert-Butylpyridine (tBP), commonly used in PSCs, is assumed to function as a charge recombination inhibitor, similar to DSSCs. However, the presence of a perovskite capping layer calls for a re-evaluation of its function in PSCs. Using TEM (transmission electron microscopy), we first confirm the role of tBP as a HTL morphology controller in PSCs. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of Li salt. We also study degradation pathways by using FTIR (Fourier transform infrared spectroscopy) and APT (atom probe tomography) to investigate and visualize in 3-dimensions the moisture content associated with the Li salt. Long-term effects, over 1000 h, due to evaporation of tBP have also been studied. Based on our findings, a PSC failure mechanism associated with the morphological change of the HTL is proposed. tBP, the morphology controller in HTL, plays a key role in this process, and thus this study highlights the need for additive materials with higher boiling points for consistent long-term performance of PSCs. PMID:27547991

  19. Role of 4-tert-Butylpyridine as a Hole Transport Layer Morphological Controller in Perovskite Solar Cells.

    PubMed

    Wang, Shen; Sina, Mahsa; Parikh, Pritesh; Uekert, Taylor; Shahbazian, Brian; Devaraj, Arun; Meng, Ying Shirley

    2016-09-14

    Hybrid organic-inorganic materials for high-efficiency, low-cost photovoltaic devices have seen rapid progress since the introduction of lead based perovskites and solid-state hole transport layers. Although majority of the materials used for perovskite solar cells (PSC) are introduced from dye-sensitized solar cells (DSSCs), the presence of a perovskite capping layer as opposed to a single dye molecule (in DSSCs) changes the interactions between the various layers in perovskite solar cells. 4-tert-Butylpyridine (tBP), commonly used in PSCs, is assumed to function as a charge recombination inhibitor, similar to DSSCs. However, the presence of a perovskite capping layer calls for a re-evaluation of its function in PSCs. Using TEM (transmission electron microscopy), we first confirm the role of tBP as a HTL morphology controller in PSCs. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of Li salt. We also study degradation pathways by using FTIR (Fourier transform infrared spectroscopy) and APT (atom probe tomography) to investigate and visualize in 3-dimensions the moisture content associated with the Li salt. Long-term effects, over 1000 h, due to evaporation of tBP have also been studied. Based on our findings, a PSC failure mechanism associated with the morphological change of the HTL is proposed. tBP, the morphology controller in HTL, plays a key role in this process, and thus this study highlights the need for additive materials with higher boiling points for consistent long-term performance of PSCs.

  20. Toward Efficient Thick Active PTB7 Photovoltaic Layers Using Diphenyl Ether as a Solvent Additive.

    PubMed

    Zheng, Yifan; Goh, Tenghooi; Fan, Pu; Shi, Wei; Yu, Junsheng; Taylor, André D

    2016-06-22

    The development of thick organic photovoltaics (OPV) could increase absorption in the active layer and ease manufacturing constraints in large-scale solar panel production. However, the efficiencies of most low-bandgap OPVs decrease substantially when the active layers exceed ∼100 nm in thickness (because of low crystallinity and a short exciton diffusion length). Herein, we report the use of solvent additive diphenyl ether (DPE) that facilitates the fabrication of thick (180 nm) active layers and triples the power conversion efficiency (PCE) of conventional thienothiophene-co-benzodithiophene polymer (PTB7)-based OPVs from 1.75 to 6.19%. These results demonstrate a PCE 20% higher than those of conventional (PTB7)-based OPV devices using 1,8-diiodooctane. Morphology studies reveal that DPE promotes the formation of nanofibrillar networks and ordered packing of PTB7 in the active layer that facilitate charge transport over longer distances. We further demonstrate that DPE improves the fill factor and photocurrent collection by enhancing the overall optical absorption, reducing the series resistance, and suppressing bimolecular recombination.

  1. Toward Efficient Thick Active PTB7 Photovoltaic Layers Using Diphenyl Ether as a Solvent Additive.

    PubMed

    Zheng, Yifan; Goh, Tenghooi; Fan, Pu; Shi, Wei; Yu, Junsheng; Taylor, André D

    2016-06-22

    The development of thick organic photovoltaics (OPV) could increase absorption in the active layer and ease manufacturing constraints in large-scale solar panel production. However, the efficiencies of most low-bandgap OPVs decrease substantially when the active layers exceed ∼100 nm in thickness (because of low crystallinity and a short exciton diffusion length). Herein, we report the use of solvent additive diphenyl ether (DPE) that facilitates the fabrication of thick (180 nm) active layers and triples the power conversion efficiency (PCE) of conventional thienothiophene-co-benzodithiophene polymer (PTB7)-based OPVs from 1.75 to 6.19%. These results demonstrate a PCE 20% higher than those of conventional (PTB7)-based OPV devices using 1,8-diiodooctane. Morphology studies reveal that DPE promotes the formation of nanofibrillar networks and ordered packing of PTB7 in the active layer that facilitate charge transport over longer distances. We further demonstrate that DPE improves the fill factor and photocurrent collection by enhancing the overall optical absorption, reducing the series resistance, and suppressing bimolecular recombination. PMID:27253271

  2. Ultrastructural study on the morphological changes in indigenous bacteria of mucous layer and chyme throughout the rat intestine.

    PubMed

    Mantani, Youhei; Ito, Eri; Nishida, Miho; Yuasa, Hideto; Masuda, Natsumi; Qi, Wang-Mei; Kawano, Junichi; Yokoyama, Toshifumi; Hoshi, Nobuhiko; Kitagawa, Hiroshi

    2015-09-01

    Indigenous bacteria in the alimentary tract are exposed to various bactericidal peptides and digestive enzymes, but the viability status and morphological changes of indigenous bacteria are unclear. Therefore, the present study aimed to ultrastructurally clarify the degeneration and viability status of indigenous bacteria in the rat intestine. The majority of indigenous bacteria in the ileal mucous layer possessed intact cytoplasm, but the cytoplasm of a few bacteria contained vacuoles. The vacuoles were more frequently found in bacteria of ileal chyme than in those of ileal mucous layer and were found in a large majority of bacteria in both the mucous layer and chyme throughout the large intestine. In the dividing bacteria of the mucous layer and chyme throughout the intestine, the ratio of area occupied by vacuoles was almost always less than 10%. Lysis or detachment of the cell wall in the indigenous bacteria was more frequently found in the large intestine than in the ileum, whereas bacterial remnants, such as cell walls, were distributed almost evenly throughout the intestine. In an experimental control of long-time-cultured Staphylococcus epidermidis on agar, similar vacuoles were also found, but cell-wall degeneration was never observed. From these findings, indigenous bacteria in the mucous layer were ultrastructurally confirmed to be the source of indigenous bacteria in the chyme. Furthermore, the results suggested that indigenous bacteria were more severely degenerated toward the large intestine and were probably degraded in the intestine.

  3. Ultrastructural study on the morphological changes in indigenous bacteria of mucous layer and chyme throughout the rat intestine.

    PubMed

    Mantani, Youhei; Ito, Eri; Nishida, Miho; Yuasa, Hideto; Masuda, Natsumi; Qi, Wang-Mei; Kawano, Junichi; Yokoyama, Toshifumi; Hoshi, Nobuhiko; Kitagawa, Hiroshi

    2015-09-01

    Indigenous bacteria in the alimentary tract are exposed to various bactericidal peptides and digestive enzymes, but the viability status and morphological changes of indigenous bacteria are unclear. Therefore, the present study aimed to ultrastructurally clarify the degeneration and viability status of indigenous bacteria in the rat intestine. The majority of indigenous bacteria in the ileal mucous layer possessed intact cytoplasm, but the cytoplasm of a few bacteria contained vacuoles. The vacuoles were more frequently found in bacteria of ileal chyme than in those of ileal mucous layer and were found in a large majority of bacteria in both the mucous layer and chyme throughout the large intestine. In the dividing bacteria of the mucous layer and chyme throughout the intestine, the ratio of area occupied by vacuoles was almost always less than 10%. Lysis or detachment of the cell wall in the indigenous bacteria was more frequently found in the large intestine than in the ileum, whereas bacterial remnants, such as cell walls, were distributed almost evenly throughout the intestine. In an experimental control of long-time-cultured Staphylococcus epidermidis on agar, similar vacuoles were also found, but cell-wall degeneration was never observed. From these findings, indigenous bacteria in the mucous layer were ultrastructurally confirmed to be the source of indigenous bacteria in the chyme. Furthermore, the results suggested that indigenous bacteria were more severely degenerated toward the large intestine and were probably degraded in the intestine. PMID:25890991

  4. Surface morphology and subsurface damaged layer of various glasses machined by 193-nm ArF excimer laser

    NASA Astrophysics Data System (ADS)

    Liao, Yunn-shiuan; Chen, Ying-Tung; Chao, Choung-Lii; Liu, Yih-Ming

    2005-01-01

    Owing to the high bonding energy, most of the glasses are removed by photo-thermal rather than photo-chemical effect when they are ablated by the 193 or 248nm excimer lasers. Typically, the machined surface is covered by re-deposited debris and the sub-surface, sometimes surface as well, is scattered with micro-cracks introduced by thermal stress generated during the process. This study aimed to investigate the nature and extent of the surface morphology and sub-surface damaged (SSD) layer induced by the laser ablation. The effects of laser parameters such as fluence, shot number and repetition rate on the morphology and SSD were discussed. An ArF excimer laser (193 nm) was used in the present study to machine glasses such as soda-lime, Zerodur and BK-7. It is found that the melt ejection and debris deposition tend to pile up higher and become denser in structure under a higher energy density, repetition rate and shot number. There are thermal stress induced lateral cracks when the debris covered top layer is etched away. Higher fluence and repetition rate tend to generate more lateral and median cracks which propagate into the substrate. The changes of mechanical properties of the SSD layer were also investigated.

  5. Temperature-activated layer-breathing vibrations in few-layer graphene.

    PubMed

    Lui, Chun Hung; Ye, Zhipeng; Keiser, Courtney; Xiao, Xun; He, Rui

    2014-08-13

    We investigated the low-frequency Raman spectra of freestanding few-layer graphene (FLG) at varying temperatures (400-900 K) controlled by laser heating. At high temperature, we observed the fundamental Raman mode for the lowest-frequency branch of rigid-plane layer-breathing mode (LBM) vibration. The mode frequency redshifts dramatically from 81 cm(-1) for bilayer to 23 cm(-1) for 8-layer. The thickness dependence is well described by a simple model of coupled oscillators. Notably, the LBM Raman response is unobservable at room temperature, and it is turned on at higher temperature (>600 K) with a steep increase of Raman intensity. The observation suggests that the LBM vibration is strongly suppressed by molecules adsorbed on the graphene surface but is activated as desorption occurs at high temperature.

  6. Active Galactic Nucleus Host Galaxy Morphologies in COSMOS

    NASA Astrophysics Data System (ADS)

    Gabor, J. M.; Impey, C. D.; Jahnke, K.; Simmons, B. D.; Trump, J. R.; Koekemoer, A. M.; Brusa, M.; Cappelluti, N.; Schinnerer, E.; Smolčić, V.; Salvato, M.; Rhodes, J. D.; Mobasher, B.; Capak, P.; Massey, R.; Leauthaud, A.; Scoville, N.

    2009-01-01

    We use Hubble Space Telescope/Advanced Camera for Surveys images and a photometric catalog of the Cosmic Evolution Survey (COSMOS) field to analyze morphologies of the host galaxies of ~400 active galactic nucleus (AGN) candidates at redshifts 0.3 < z < 1.0. We compare the AGN hosts with a sample of nonactive galaxies drawn from the COSMOS field to match the magnitude and redshift distribution of the AGN hosts. We perform two-dimensional surface brightness modeling with GALFIT to yield host galaxy and nuclear point source magnitudes. X-ray-selected AGN host galaxy morphologies span a substantial range that peaks between those of early-type, bulge-dominated and late-type, disk-dominated systems. We also measure the asymmetry and concentration of the host galaxies. Unaccounted for, the nuclear point source can significantly bias results of these measured structural parameters, so we subtract the best-fit point source component to obtain images of the underlying host galaxies. Our concentration measurements reinforce the findings of our two-dimensional morphology fits, placing X-ray AGN hosts between early- and late-type inactive galaxies. AGN host asymmetry distributions are consistent with those of control galaxies. Combined with a lack of excess companion galaxies around AGN, the asymmetry distributions indicate that strong interactions are no more prevalent among AGN than normal galaxies. In light of recent work, these results suggest that the host galaxies of AGN at these X-ray luminosities may be in a transition from disk-dominated to bulge-dominated, but that this transition is not typically triggered by major mergers. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc, under NASA contract NAS 5-26555; also based on data collected at: the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with

  7. Passive and active control of boundary layer transition

    NASA Astrophysics Data System (ADS)

    Nosenchuck, Daniel Mark

    It is well known that laminar-turbulent boundary layer transition is initiated by the formation of Tollmien-Schlichting laminar instability waves. The amplification rates of these waves are strongly dependent on the shape of the boundary layer velocity profile. Consequently, the transition process can be controlled by modifying the velocity profile. This can be accomplished by controlling the pressure gradient (dp/dx), using boundary layer suction, installing surface roughness elements, or by surface heating or cooling. Methods used to modify the transition process through changes in the mean velocity profile are called "passive" in this paper. There exists a large set of experiments and theory on the application of passive methods for boundary layer control. In the present work only surface heating will be addressed.Transition measurements were made on a heated flat plate in water. Results are presented for several plate wall temperature distributions. An increase by a factor of 2.5 in transition Reynolds number was observed for a 5°C isothermal wall overheat. Buoyancy effects on transition were minimal due to the small Richardson and Grashof numbers encountered in the experiments.The amplification of laminar instability waves is comparatively to process, taking place over many boundary layer thicknesses. After the slow amplification of the laminar instability waves, transition occurs by a strong three dimensional dynamic instability. It appears possible to attenuate (or reinforce) the instability waves by introducing amplitude-and phase-controlled perturbations into the laminar boundary layer using feedback control system. This method is called "active" control and forms the larger part of the research reported in this thesis.A combination of sensors, activators and feedback control electronics is required for active control. The sensors used in the experiments are flush-mounted hot film wall shear robes. A new type of activator was developed using thin, flush

  8. Estimating Active Layer Thickness from Remotely Sensed Surface Deformation

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Zhang, T.; Wahr, J. M.

    2010-12-01

    We estimate active layer thickness (ALT) from remotely sensed surface subsidence during thawing seasons derived from interferometric synthetic aperture radar (InSAR) measurements. Ground ice takes up more volume than ground water, so as the soil thaws in summer and the active layer deepens, the ground subsides. The volume of melted ground water during the summer thaw determines seasonal subsidence. ALT is defined as the maximum thaw depth at the end of a thawing season. By using InSAR to measure surface subsidence between the start and end of summer season, one can estimate the depth of thaw over a large area (typically 100 km by 100 km). We developed an ALT retrieval algorithm integrating InSAR-derived surface subsidence, observed soil texture, organic matter content, and moisture content. We validated this algorithm in the continuous permafrost area on the North Slope of Alaska. Based on InSAR measurements using ERS-1/2 SAR data, our estimated values match in situ measurements of ALT within 1--10 cm at Circumpolar Active Layer Monitoring (CALM) sites within the study area. The active layer plays a key role in land surface processes in cold regions. Current measurements of ALT using mechanical probing, frost/thaw tubes, or inferred from temperature measurements are of high quality, but limited in spatial coverage. Using InSAR to estimate ALT greatly expands the spatial coverage of ALT observations.

  9. EMG activity across gait and incline: The impact of muscular activity on human morphology

    PubMed Central

    Wall-Scheffler, Cara M.; Chumanov, Elizabeth; Steudel-Numbers, Karen; Heiderscheit, Bryan

    2010-01-01

    The study of human evolution depends upon a fair assessment of the ability of hominin individuals to gain access to necessary resources. We expect that the morphology of extant and extinct populations represents a successful locomotory system that allowed individuals to move across the environment gaining access to food, water and mates while still maintaining excess energy to allocate to reproduction. Our assessment of locomotor morphology must then incorporate tests of fitness within realistic environments—environments that themselves vary in terrain and whose negotiation requires a variety of gait and speeds. This study assesses muscular activity (measured as the integrated signal from surface electromyography) of seven thigh and hip muscle groups during walking and running across a wide range of speeds and inclines, in order to systematically assess the role that morphology can play in minimizing muscular activity and thus energy expenditure. Our data suggest that humans are better adapted to walking than running at any slope, as evidenced by small confidence intervals and even trends across speed and incline. We find that while increasing task intensity unsurprisingly increases muscular activity in the lower limb, individuals with longer limbs show significantly reduced activity during both walking and running, especially in the hip adductors, gluteus maximus and hamstring muscles. People with a broader pelvis show significantly reduced activity while walking in the hip adductor and hamstring muscles. PMID:20623603

  10. Morphology-dependent stimulated Raman scattering imaging. II. Experimental studies of solvent structure in the diffuse electric double layer

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Xiang; Moortgat, Philip A.; Aker, Pamela M.

    1996-11-01

    Experimental confirmation that morphology-dependent stimulated Raman scattering can be used as an optical imaging technique is given. The water structure variations present at a charged water/air interface have been mapped. The measured structure variations track precisely that given by the Gouy-Chapman theory. We present, to our knowledge, the first experimental investigations of water solvent response in the diffuse part of the electric double layer. Imaging experiments on droplets charged to both positive and negative values have enabled us to determine the neutral water/air interface potential.

  11. Morphology-dependent stimulated Raman scattering imaging. II. Experimental studies of solvent structure in the diffuse electric double layer

    SciTech Connect

    Zhang, J.; Moortgat, P.A.; Aker, P.M.

    1996-11-01

    Experimental confirmation that morphology-dependent stimulated Raman scattering can be used as an optical imaging technique is given. The water structure variations present at a charged water/air interface have been mapped. The measured structure variations track precisely that given by the Gouy{endash}Chapman theory. We present, to our knowledge, the first experimental investigations of water solvent response in the diffuse part of the electric double layer. Imaging experiments on droplets charged to both positive and negative values have enabled us to determine the neutral water/air interface potential. {copyright} {ital 1996 American Institute of Physics.}

  12. A method based on iterative morphological filtering and multiple scattering for detecting layer boundaries and extinction coefficients with LIDAR

    NASA Astrophysics Data System (ADS)

    Li, Meng; Jiang, Li-Hui; Xiong, Xing-Long; Ma, Yu-Zhao; Liu, Jie-Sheng

    2016-08-01

    Layer boundaries detection with LIDAR is of great significance for the meteorological and environmental research. Apart from the background noise, multiple scattering can also seriously affect the detection results in LIDAR signal processing. To alleviate these issues, a novel approach was proposed based upon morphological filtering and multiple scattering correction with multiple iterations, which essentially acts as a weighted algorithm with multiple scattering factors in different filtering scales, and applies integral extinction coefficients as media to perform correction. Simulations on artificial signals and real LIDAR signals support this approach.

  13. Carbon nanotubes supported cerium dioxide and platinum nanohybrids: Layer-by-layer synthesis and enhanced electrocatalytic activity for methanol oxidation

    NASA Astrophysics Data System (ADS)

    Lou, Xinyuan; Chen, Jiayi; Wang, Mengdi; Gu, Jialei; Wu, Ping; Sun, Dongmei; Tang, Yawen

    2015-08-01

    We successfully synthesize carbon nanotubes (CNTs) supported cerium dioxide and platinum (Pt/CeO2/CNTs) nanohybrids via layer-by-layer assembly. The composition, morphology and structure of the as-prepared Pt/CeO2/CNTs nanohybrids are characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDX), selected-area electron diffraction (SAED), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and inductively coupled plasma atomic emission spectrometry (ICP-AES). By comparison of the electrocatalytic properties of the Pt/CeO2/CNTs with the Pt/CNTs, we systematically investigate the promotion effect of CeO2 on the Pt/CeO2/CNTs catalysts towards methanol oxidation. It is found that the introduction of CeO2 not only enhances the electrocatalytic activity and stability of the Pt/CeO2/CNTs catalyst for methanol oxidation but also minimizes the CO poisoning, probably accounting for the good oxygen carrying capacity of CeO2 and its high stability in acidic solution.

  14. Morphology and Transport Properties of Novel Polymer Nanocomposites Resulted from Melt Processing of Polyvinylacetate Substrates Coated with Layer-by-Layer Assemblies

    NASA Astrophysics Data System (ADS)

    Soltani, Iman; Spontak, Richard J.

    Novel polymer nanocomposites (PNCs) were processed through layer-by-layer (LBL) deposition of clay and polyethylene terephthalate ionomer layers on polyvinylacetate (PVAc) substrates, followed by repetitive melt pressing of coated samples to crush LBL assemblies into the polymeric matrix. The increase in the clay content in resulted PNCs prepared through similar LBL coatings, relative to previously studied hydrophobic polystyrene-based nanocomposites, postulated superiority of PVAc, with relatively higher hydrophilicity, to interact with LBL assemblies. Also, these PNCs showed relatively good barrier improvement against transport of oxygen and carbon dioxide gases, proposing the scavenging effect of LBL assemblies crushed portions as highly tortuous labyrinths with high aspect ratios, comprising edge-edge flocculated exfoliated clay platelets, observed through transmission electron micrographs. However, combinative morphological investigations through optical microscopy, x-ray diffractometry, and transmission electron microscopy proposed low global dispersion of clay throughout polymeric matrix, conjecturing insufficient intensity of stress applied through cyclic melt pressing, and/or slight thermal degradation of samples via extended times of processing at high temperatures.

  15. Morphological changes in the blastocyst of the western spotted skunk during activation from delayed implantation.

    PubMed

    Enders, A C; Schlafke, S; Hubbard, N E; Mead, R A

    1986-03-01

    Blastocysts collected from the spotted skunk during delay of implantation, early activation and late activation demonstrate three-tiered growth and developmental changes. The slow-growing blastocyst from the several months of delay is small (less than 1.1 mm) with a rounded inner cell mass consisting of clusters of rounded, lipid-filled cells. During the several days of early activation, the lipid in both inner cell mass and trophoblast diminishes, polyribosomes increase in number, and the endodermal layer differentiates as the blastocyst grows (1.2-1.6 mm). At activation the inner cell mass flattens, becomes uncovered by polar trophoblast, and forms a disc of columnar epiblast cells. The blastocyst expands rapidly during the last 24-48 h prior to implantation to 1.7-2.0 mm, and the trophoblast becomes cuboidal with a marked endocytotic apparatus. The morphological evidence, together with previous studies of protein and RNA synthesis, suggests a tooling-up period during early activation with progressive increases in rates of growth and differentiation in the last hours as implantation approaches.

  16. Comparative morphology of three types of projection-identified pyramidal neurons in the superficial layers of cat visual cortex.

    PubMed

    Matsubara, J A; Chase, R; Thejomayen, M

    1996-02-26

    The morphology and dendritic organization of corticocortical neurons in the superficial layers of area 18 that project to area 17 were studied by intracellular injection of lucifer yellow in the fixed-slice preparation. This corticocortical population contains primarily standard pyramidal cells, but occasional nonpyramidal, modified, fusiform, star, and inverted pyramidal cells were also seen. All cell types were present throughout layer 2 and in the upper and middle parts of layer 3. Standard pyramidal cells were found exclusively in lower layer 3. The mean somatic area of the area 17 projecting neurons was 251 microns 2. The width of basal dendritic fields was correlated to cell size for standard pyramidal cells but not for the other cell types. Next, the morphology and dendritic organization of the area 17 projecting neurons were compared to the pyramidal cells of the local horizontal patch networks and of the callosal system. The depth profile of the area 17 projecting and callosal pyramidal groups was virtually identical, peaking at 400 microns from the pial surface, whereas the local patch pyramidal group peaked at 281 microns. The local patch, area 17 projecting, and callosal pyramidal cells displayed increasingly larger mean somatic areas and basilar dendritic field width measurements. The number of basal dendritic branch points was greatest for callosal cells, and it was indistinguishable between local patch and area 17 projecting neurons. In the tangential plane, circular dendritic fields were observed on all callosal cells, but they were found on only approximately half of the local patch and area 17 projecting neurons. The remaining local patch and area 17 projecting neurons displayed mediolaterally and anteroposteriorly elongated basal dendritic fields, respectively. PMID:8866848

  17. Active microwave remote sensing of an anisotropic random medium layer

    NASA Technical Reports Server (NTRS)

    Lee, J. K.; Kong, J. A.

    1985-01-01

    A two-layer anisotropic random medium model has been developed to study the active remote sensing of the earth. The dyadic Green's function for a two-layer anisotropic medium is developed and used in conjunction with the first-order Born approximation to calculate the backscattering coefficients. It is shown that strong cross-polarization occurs in the single scattering process and is indispensable in the interpretation of radar measurements of sea ice at different frequencies, polarizations, and viewing angles. The effects of anisotropy on the angular responses of backscattering coefficients are also illustrated.

  18. Synthesis of Zn/Co/Fe-layered double hydroxide nanowires with controllable morphology in a water-in-oil microemulsion

    SciTech Connect

    Wu Hongyu; Jiao Qingze; Zhao Yun; Huang Silu; Li Xuefei; Liu Hongbo; Zhou Mingji

    2010-02-15

    The Zn/Co/Fe-layered double hydroxide nanowires were synthesized via a reverse microemulsion method by using cetyltrimethyl ammonium bromide (CTAB) /n-hexane/n-hexanol/water as Soft-Template. ZnSO{sub 4}, CoSO{sub 4}, Fe{sub 2}(SO{sub 4}){sub 3} and urea were used as raw materials. The influence of reaction temperature, time, urea concentration and Cn (molar ratio of cetyltrimethyl ammonium bromide to water) on the structure and morphology of Zn/Co/Fe-layered double hydroxides was investigated. The samples were characterized using Transmission Electron Microscopy (TEM), Inductively Coupled Plasma (ICP), X-ray Diffraction (XRD) and Infrared Absorption Spectrum (IR). The results indicate that higher temperature is beneficial to the formation of layered double hydroxides, but particles apart from nanowires could be produced if temperature is up to 120 deg. C. By varying the temperature, reaction time, urea concentration and Cn, we got the optimum conditions of synthesizing uniform Zn/Co/Fe-layered double hydroxide nanowires: 100 deg. C, more than 12 h, Cn: 30-33, urea concentration: 0.3 M.

  19. Critical heat flux maxima resulting from the controlled morphology of nanoporous hydrophilic surface layers

    NASA Astrophysics Data System (ADS)

    Tetreault-Friend, Melanie; Azizian, Reza; Bucci, Matteo; McKrell, Thomas; Buongiorno, Jacopo; Rubner, Michael; Cohen, Robert

    2016-06-01

    Porous hydrophilic surfaces have been shown to enhance the critical heat flux (CHF) in boiling heat transfer. In this work, the separate effects of pore size and porous layer thickness on the CHF of saturated water at atmospheric pressure were experimentally investigated using carefully engineered surfaces. It was shown that, for a fixed pore diameter (˜20 nm), there is an optimum layer thickness (˜2 μm), for which the CHF value is maximum, corresponding to ˜115% enhancement over the value for uncoated surfaces. Similarly, a maximum CHF value (˜100% above the uncoated surface CHF) was observed while changing the pore size at a constant layer thickness (˜1 μm). To explain these CHF maxima, we propose a mechanistic model that can capture the effect of pore size and pore thickness on CHF. The good agreement found between the model and experimental data supports the hypothesis that CHF is governed by the competition between capillary wicking, viscous pressure drop and evaporation, as well as conduction heat transfer within the porous layer. The model can be used to guide the development of engineered surfaces with superior boiling performance.

  20. Basal cell carcinoma develops in contact with the epidermal basal cell layer - a three-dimensional morphological study.

    PubMed

    Pirici, Ionica; Ciurea, Marius Eugen; Mîndrilă, Ion; Avrămoiu, Ioan; Pirici, Alexandru; Nicola, Monica Georgiana; Rogoveanu, Otilia Constantina

    2016-01-01

    Basal cell carcinoma is the most common malignant tumor of the skin, and it develops most frequently on the areas of the body that make its treatment and care extremely difficult, especially in cases of neglecting or aggressive growth and invasion. Both typical mild cases as well as locally aggressive tumor types do not tend to metastasize, and it has been postulated that they should share some common biological and morphological features that might explain this behavior. In this study, we have utilized a high-resolution three-dimensional reconstruction technique on pathological samples from 15 cases of common aggressive (fibrosing and adenoid types) and mild (superficial type) basal cell carcinomas, and showed that all these types shared contact points and bridges with the underlying basal cell layer of the epidermis or with the outmost layer of the hair follicle. The connections found had in fact the highest number for fibrosing type (100%), compared to the superficial (85.71%) and adenoid (55%) types. The morphology of the connection bridges was also different, adjacent moderate to abundant inflammatory infiltrate seeming to lead to a loss of basaloid features in these areas. For the adenoid type, tumor islands seemed to be connected also to each other more strongly, forming a common "tumor lace", and while it has been showed that superficial and fibrosing types have higher recurrence risks, all together these data might iterate a connection between the number of bridging points and the biological and clinical manifestation of this skin tumor. PMID:27151694

  1. Nondestructive dislocation delineation using topographically enhanced imaging of surface morphologies in 4H-SiC epitaxial layers

    NASA Astrophysics Data System (ADS)

    Picard, Yoosuf N.; Liu, Kendrick X.; Stahlbush, Robert E.; Twigg, Mark E.; Zhang, Xuan; Skowronski, Marek

    2008-04-01

    The morphology of surface features generated by dislocations present at 4H-SiC epitaxial layer surfaces was investigated by forescattered electron detection (FED) inside a conventional scanning electron microscope. Various growth pit morphologies were correlated to dislocation types using molten KOH etching. Specifically, sharp-apex pits and stripe-shaped pits were consistently linked to screw and edge dislocations, respectively. The size and depth of these growth pits were measured by atomic force microscopy (AFM). Tail-like features were observed by FED emanating from sharp-apex pits and verified by Nomarski optical microscopy (NOM). A mechanism is proposed to explain the FED contrast exhibited by these tail-like features. This mechanism relates the nature of step-flow and spiral growth in the wake of a screw dislocation to the surface distortions resulting in such tail-like features. The Burgers vector direction can thus be determined based on a purely morphological analysis of these tail-like features. The results of this study illustrate the various capabilities of FED for surface imaging as compared to AFM and NOM. The potential for utilizing FED to map dislocation-associated growth pits is discussed.

  2. Graphene as transparent conducting electrodes in organic photovoltaics: studies in graphene morphology, hole transporting layers, and counter electrodes.

    PubMed

    Park, Hyesung; Brown, Patrick R; Bulović, Vladimir; Kong, Jing

    2012-01-11

    In this work, organic photovoltaics (OPV) with graphene electrodes are constructed where the effect of graphene morphology, hole transporting layers (HTL), and counter electrodes are presented. Instead of the conventional poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) PEDOT:PSS HTL, an alternative transition metal oxide HTL (molybdenum oxide (MoO(3))) is investigated to address the issue of surface immiscibility between graphene and PEDOT:PSS. Graphene films considered here are synthesized via low-pressure chemical vapor deposition (LPCVD) using a copper catalyst and experimental issues concerning the transfer of synthesized graphene onto the substrates of OPV are discussed. The morphology of the graphene electrode and HTL wettability on the graphene surface are shown to play important roles in the successful integration of graphene films into the OPV devices. The effect of various cathodes on the device performance is also studied. These factors (i.e., suitable HTL, graphene surface morphology and residues, and the choice of well-matching counter electrodes) will provide better understanding in utilizing graphene films as transparent conducting electrodes in future solar cell applications. PMID:22107487

  3. Morphological expression of active tectonics in the Southern Alps

    NASA Astrophysics Data System (ADS)

    Robl, Jörg; Heberer, Bianca; Neubauer, Franz; Hergarten, Stefan

    2015-04-01

    rates are not well constrained for the entire domain. Despite of that, extensive karstification in some areas limits the validity of a morphometric analysis in particular of the upper reaches of the drainage system and leads to a long term persistence of landforms (e.g. plateaus). In this study we focus on the drainage pattern of the eastern Southern Alps and the adjacent southern foreland basin. We use a high-resolution digital elevation model and a novel numerical approach to extract characteristic parameters of the morphology for the entire eastern Southern Alps with a high spatial resolution. We explore deviations in the steepness of channels from an equilibrium state and knick-points in longitudinal channel profiles and interpret these features in terms of (a) active tectonics, and variable uplift rates, (b) lithological effects like erodibility contrasts and karstification, and (c) base level lowering caused by glacial erosion and Messinian preconditioning. The drainage system of the Adige shows the most significant deviations from a fluvial equilibrium. This is documented in the normalized steepness index of the main channel and all tributaries as well as in the longitudinal channel profile. The main channel shows several sections of downstream steepening and extremely low channel gradients in the lower reach. Similar deviations are also observed in the Brenta catchment situated east of the Adige drainage system. In contrast to the two large western catchments of the study region, the Piave and particularly the Tagliamento catchment show well graded channel profiles and uniform normalized steepness indices despite of the glacial history. This clear west to east trend from highly disturbed to overall well graded channels has never been documented before and may be explained in the light of increased uplift rates in the east and differences in onset and timing of topography formation between the western and eastern sector of the study region.

  4. Layer-by-layer assembly of TiO2 nanowire/carbon nanotube films and characterization of their photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Darányi, Mária; Csesznok, Tamás; Kukovecz, Ákos; Kónya, Zoltán; Kiricsi, Imre; Ajayan, Pulickel M.; Vajtai, Robert

    2011-05-01

    We report on the layer-by-layer (LbL) formation of TiO2-MWNT-TiO2 coatings on quartz with either trititanate derived TiO2 nanowires or Degussa P25 as the photocatalytically active material. The optimized deposition sequence is discussed in detail and the morphology of the prepared coatings is analyzed by SEM and XRD. The heterogeneous photocatalytic performance of the coatings was tested in the methyl orange oxidation reaction. The apparent first order rate constant fell in the 0.01-0.20 h - 1 range over a 2.5 × 2.5 cm2 film depending on the type and the thickness of the titanate coating. Building a multiwall carbon nanotube layer into the middle of the layer improved the photocatalytic activity for each material for all of the studied thicknesses. P25 based films performed 2-5 times better than TiO2 nanowire films; however, the pores in the P25 based films were largely blocked because the isotropic P25 nanoparticles form closely packed layers by themselves and even more so with the comparably sized multiwall carbon nanotubes. Therefore, films derived from titanate nanowires appear to be more suitable for use as multifunctional, photocatalytically active filtration media.

  5. Effects of flow and colony morphology on the thermal boundary layer of corals.

    PubMed

    Jimenez, Isabel M; Kühl, Michael; Larkum, Anthony W D; Ralph, Peter J

    2011-12-01

    The thermal microenvironment of corals and the thermal effects of changing flow and radiation are critical to understanding heat-induced coral bleaching, a stress response resulting from the destruction of the symbiosis between corals and their photosynthetic microalgae. Temperature microsensor measurements at the surface of illuminated stony corals with uneven surface topography (Leptastrea purpurea and Platygyra sinensis) revealed millimetre-scale variations in surface temperature and thermal boundary layer (TBL) that may help understand the patchy nature of coral bleaching within single colonies. The effect of water flow on the thermal microenvironment was investigated in hemispherical and branching corals (Porites lobata and Stylophora pistillata, respectively) in a flow chamber experiment. For both coral types, the thickness of the TBL decreased exponentially from 2.5 mm at quasi-stagnant flow (0.3 cm s(-1)), to 1 mm at 5 cm s(-1), with an exponent approximately 0.5 consistent with predictions from the heat transfer theory for simple geometrical objects and typical of laminar boundary layer processes. Measurements of mass transfer across the diffusive boundary layer using O(2) microelectrodes revealed a greater exponent for mass transfer when compared with heat transfer, indicating that heat and mass transfer at the surface of corals are not exactly analogous processes.

  6. Effects of flow and colony morphology on the thermal boundary layer of corals

    PubMed Central

    Jimenez, Isabel M.; Kühl, Michael; Larkum, Anthony W. D.; Ralph, Peter J.

    2011-01-01

    The thermal microenvironment of corals and the thermal effects of changing flow and radiation are critical to understanding heat-induced coral bleaching, a stress response resulting from the destruction of the symbiosis between corals and their photosynthetic microalgae. Temperature microsensor measurements at the surface of illuminated stony corals with uneven surface topography (Leptastrea purpurea and Platygyra sinensis) revealed millimetre-scale variations in surface temperature and thermal boundary layer (TBL) that may help understand the patchy nature of coral bleaching within single colonies. The effect of water flow on the thermal microenvironment was investigated in hemispherical and branching corals (Porites lobata and Stylophora pistillata, respectively) in a flow chamber experiment. For both coral types, the thickness of the TBL decreased exponentially from 2.5 mm at quasi-stagnant flow (0.3 cm s−1), to 1 mm at 5 cm s−1, with an exponent approximately 0.5 consistent with predictions from the heat transfer theory for simple geometrical objects and typical of laminar boundary layer processes. Measurements of mass transfer across the diffusive boundary layer using O2 microelectrodes revealed a greater exponent for mass transfer when compared with heat transfer, indicating that heat and mass transfer at the surface of corals are not exactly analogous processes. PMID:21602322

  7. Influence of active layer and support layer surface structures on organic fouling propensity of thin-film composite forward osmosis membranes.

    PubMed

    Lu, Xinglin; Arias Chavez, Laura H; Romero-Vargas Castrillón, Santiago; Ma, Jun; Elimelech, Menachem

    2015-02-01

    In this study, we investigate the influence of surface structure on the fouling propensity of thin-film composite (TFC) forward osmosis (FO) membranes. Specifically, we compare membranes fabricated through identical procedures except for the use of different solvents (dimethylformamide, DMF and N-methyl-2-pyrrolidinone, NMP) during phase separation. FO fouling experiments were carried out with a feed solution containing a model organic foulant. The TFC membranes fabricated using NMP (NMP-TFC) had significantly less flux decline (7.47 ± 0.15%) when compared to the membranes fabricated using DMF (DMF-TFC, 12.70 ± 2.62% flux decline). Water flux was also more easily recovered through physical cleaning for the NMP-TFC membrane. To determine the fundamental cause of these differences in fouling propensity, the active and support layers of the membranes were extensively characterized for physical and chemical characteristics relevant to fouling behavior. Polyamide surface roughness was found to dominate all other investigated factors in determining the fouling propensities of our membranes relative to each other. The high roughness polyamide surface of the DMF-TFC membrane was also rich in larger leaf-like structures, whereas the lower roughness NMP-TFC membrane polyamide layer contained more nodular and smaller features. The support layers of the two membrane types were also characterized for their morphological properties, and the relation between support layer surface structure and polyamide active layer formation was discussed. Taken together, our findings indicate that support layer structure has a significant impact on the fouling propensity of the active layer, and this impact should be considered in the design of support layer structures for TFC membranes.

  8. Influence of active layer and support layer surface structures on organic fouling propensity of thin-film composite forward osmosis membranes.

    PubMed

    Lu, Xinglin; Arias Chavez, Laura H; Romero-Vargas Castrillón, Santiago; Ma, Jun; Elimelech, Menachem

    2015-02-01

    In this study, we investigate the influence of surface structure on the fouling propensity of thin-film composite (TFC) forward osmosis (FO) membranes. Specifically, we compare membranes fabricated through identical procedures except for the use of different solvents (dimethylformamide, DMF and N-methyl-2-pyrrolidinone, NMP) during phase separation. FO fouling experiments were carried out with a feed solution containing a model organic foulant. The TFC membranes fabricated using NMP (NMP-TFC) had significantly less flux decline (7.47 ± 0.15%) when compared to the membranes fabricated using DMF (DMF-TFC, 12.70 ± 2.62% flux decline). Water flux was also more easily recovered through physical cleaning for the NMP-TFC membrane. To determine the fundamental cause of these differences in fouling propensity, the active and support layers of the membranes were extensively characterized for physical and chemical characteristics relevant to fouling behavior. Polyamide surface roughness was found to dominate all other investigated factors in determining the fouling propensities of our membranes relative to each other. The high roughness polyamide surface of the DMF-TFC membrane was also rich in larger leaf-like structures, whereas the lower roughness NMP-TFC membrane polyamide layer contained more nodular and smaller features. The support layers of the two membrane types were also characterized for their morphological properties, and the relation between support layer surface structure and polyamide active layer formation was discussed. Taken together, our findings indicate that support layer structure has a significant impact on the fouling propensity of the active layer, and this impact should be considered in the design of support layer structures for TFC membranes. PMID:25564877

  9. The energy components of stacked chromatin layers explain the morphology, dimensions and mechanical properties of metaphase chromosomes.

    PubMed

    Daban, Joan-Ramon

    2014-03-01

    The measurement of the dimensions of metaphase chromosomes in different animal and plant karyotypes prepared in different laboratories indicates that chromatids have a great variety of sizes which are dependent on the amount of DNA that they contain. However, all chromatids are elongated cylinders that have relatively similar shape proportions (length to diameter ratio approx. 13). To explain this geometry, it is considered that chromosomes are self-organizing structures formed by stacked layers of planar chromatin and that the energy of nucleosome-nucleosome interactions between chromatin layers inside the chromatid is approximately 3.6 × 10(-20) J per nucleosome, which is the value reported by other authors for internucleosome interactions in chromatin fibres. Nucleosomes in the periphery of the chromatid are in contact with the medium; they cannot fully interact with bulk chromatin within layers and this generates a surface potential that destabilizes the structure. Chromatids are smooth cylinders because this morphology has a lower surface energy than structures having irregular surfaces. The elongated shape of chromatids can be explained if the destabilizing surface potential is higher in the telomeres (approx. 0.16 mJ m(-2)) than in the lateral surface (approx. 0.012 mJ m(-2)). The results obtained by other authors in experimental studies of chromosome mechanics have been used to test the proposed supramolecular structure. It is demonstrated quantitatively that internucleosome interactions between chromatin layers can justify the work required for elastic chromosome stretching (approx. 0.1 pJ for large chromosomes). The high amount of work (up to approx. 10 pJ) required for large chromosome extensions is probably absorbed by chromatin layers through a mechanism involving nucleosome unwrapping. PMID:24402918

  10. The energy components of stacked chromatin layers explain the morphology, dimensions and mechanical properties of metaphase chromosomes.

    PubMed

    Daban, Joan-Ramon

    2014-03-01

    The measurement of the dimensions of metaphase chromosomes in different animal and plant karyotypes prepared in different laboratories indicates that chromatids have a great variety of sizes which are dependent on the amount of DNA that they contain. However, all chromatids are elongated cylinders that have relatively similar shape proportions (length to diameter ratio approx. 13). To explain this geometry, it is considered that chromosomes are self-organizing structures formed by stacked layers of planar chromatin and that the energy of nucleosome-nucleosome interactions between chromatin layers inside the chromatid is approximately 3.6 × 10(-20) J per nucleosome, which is the value reported by other authors for internucleosome interactions in chromatin fibres. Nucleosomes in the periphery of the chromatid are in contact with the medium; they cannot fully interact with bulk chromatin within layers and this generates a surface potential that destabilizes the structure. Chromatids are smooth cylinders because this morphology has a lower surface energy than structures having irregular surfaces. The elongated shape of chromatids can be explained if the destabilizing surface potential is higher in the telomeres (approx. 0.16 mJ m(-2)) than in the lateral surface (approx. 0.012 mJ m(-2)). The results obtained by other authors in experimental studies of chromosome mechanics have been used to test the proposed supramolecular structure. It is demonstrated quantitatively that internucleosome interactions between chromatin layers can justify the work required for elastic chromosome stretching (approx. 0.1 pJ for large chromosomes). The high amount of work (up to approx. 10 pJ) required for large chromosome extensions is probably absorbed by chromatin layers through a mechanism involving nucleosome unwrapping.

  11. Evolution & Phylogenetic Analysis: Classroom Activities for Investigating Molecular & Morphological Concepts

    ERIC Educational Resources Information Center

    Franklin, Wilfred A.

    2010-01-01

    In a flexible multisession laboratory, students investigate concepts of phylogenetic analysis at both the molecular and the morphological level. Students finish by conducting their own analysis on a collection of skeletons representing the major phyla of vertebrates, a collection of primate skulls, or a collection of hominid skulls.

  12. Active layer hydrology for Imnavait Creek, Toolik, Alaska

    SciTech Connect

    Kane, D.L.

    1986-01-01

    In the annual hydrologic cycle, snowmelt is the most significant event at Imnavait Creek located near Toolik Lake, Alaska. Precipitation that has accumulated for more than 6 months on the surface melts in a relatively short period of 7 to 10 days once sustained melting occurs. During the ablation period, runoff dominates the hydrologic cycle. Some meltwater goes to rewetting the organic soils in the active layer. The remainder is lost primarily because of evaporation, since transpiration is not a very active process at this time. Following the snowmelt period, evapotranspiration becomes the dominate process, with base flow contributing the other watershed losses. It is important to note that the water initally lost by evapotranspiration entered the organic layer during melt. This water from the snowpack ensures that each year the various plant communities will have sufficient water to start a new summer of growth.

  13. How Orthography Modulates Morphological Priming: Subliminal Kanji Activation in Japanese

    PubMed Central

    Nakano, Yoko; Ikemoto, Yu; Jacob, Gunnar; Clahsen, Harald

    2016-01-01

    The current study investigates to what extent masked morphological priming is modulated by language-particular properties, specifically by its writing system. We present results from two masked priming experiments investigating the processing of complex Japanese words written in less common (moraic) scripts. In Experiment 1, participants performed lexical decisions on target verbs; these were preceded by primes which were either (i) a past-tense form of the same verb, (ii) a stem-related form with the epenthetic vowel -i, (iii) a semantically-related form, and (iv) a phonologically-related form. Significant priming effects were obtained for prime types (i), (ii), and (iii), but not for (iv). This pattern of results differs from previous findings on languages with alphabetic scripts, which found reliable masked priming effects for morphologically related prime/target pairs of type (i), but not for non-affixal and semantically-related primes of types (ii), and (iii). In Experiment 2, we measured priming effects for prime/target pairs which are neither morphologically, semantically, phonologically nor - as presented in their moraic scripts—orthographically related, but which—in their commonly written form—share the same kanji, which are logograms adopted from Chinese. The results showed a significant priming effect, with faster lexical-decision times for kanji-related prime/target pairs relative to unrelated ones. We conclude that affix-stripping is insufficient to account for masked morphological priming effects across languages, but that language-particular properties (in the case of Japanese, the writing system) affect the processing of (morphologically) complex words. PMID:27065895

  14. How Orthography Modulates Morphological Priming: Subliminal Kanji Activation in Japanese.

    PubMed

    Nakano, Yoko; Ikemoto, Yu; Jacob, Gunnar; Clahsen, Harald

    2016-01-01

    The current study investigates to what extent masked morphological priming is modulated by language-particular properties, specifically by its writing system. We present results from two masked priming experiments investigating the processing of complex Japanese words written in less common (moraic) scripts. In Experiment 1, participants performed lexical decisions on target verbs; these were preceded by primes which were either (i) a past-tense form of the same verb, (ii) a stem-related form with the epenthetic vowel -i, (iii) a semantically-related form, and (iv) a phonologically-related form. Significant priming effects were obtained for prime types (i), (ii), and (iii), but not for (iv). This pattern of results differs from previous findings on languages with alphabetic scripts, which found reliable masked priming effects for morphologically related prime/target pairs of type (i), but not for non-affixal and semantically-related primes of types (ii), and (iii). In Experiment 2, we measured priming effects for prime/target pairs which are neither morphologically, semantically, phonologically nor - as presented in their moraic scripts-orthographically related, but which-in their commonly written form-share the same kanji, which are logograms adopted from Chinese. The results showed a significant priming effect, with faster lexical-decision times for kanji-related prime/target pairs relative to unrelated ones. We conclude that affix-stripping is insufficient to account for masked morphological priming effects across languages, but that language-particular properties (in the case of Japanese, the writing system) affect the processing of (morphologically) complex words. PMID:27065895

  15. Layered shielding design for an active neutron interrogation system

    NASA Astrophysics Data System (ADS)

    Whetstone, Zachary D.; Kearfott, Kimberlee J.

    2016-08-01

    The use of source and detector shields in active neutron interrogation can improve detector signal. In simulations, a shielded detector with a source rotated π/3 rad relative to the opening decreased neutron flux roughly three orders of magnitude. Several realistic source and detector shield configurations were simulated. A layered design reduced neutron and secondary photon flux in the detector by approximately one order of magnitude for a deuterium-tritium source. The shield arrangement can be adapted for a portable, modular design.

  16. Morphology and surface-plasmon resonance of silver nanoparticles sandwiched between Si3N4 and BN layers

    NASA Astrophysics Data System (ADS)

    Toudert, J.; Camelio, S.; Babonneau, D.; Denanot, M.-F.; Girardeau, T.; Espiños, J. P.; Yubero, F.; Gonzalez-Elipe, A. R.

    2005-12-01

    Nanocermet trilayered thin films consisting of silver nanoclusters sandwiched between two dielectric layers (the buffer and the cap) have been synthesized by ion-beam sputtering with an alternate deposition of the metal and the dielectric species. The influence of the amount of silver, the nature of the buffer and the cap (BN or Si3N4), and a time delay before the cap deposition on clusters morphology and repartition have been investigated by transmission electron microscopy. It has been observed that the clusters display truncated ellipsoidal shapes in which the height to diameter ratio H /D decreases as the amount of deposited silver increases. For a given amount of silver, this ratio is lower in the case of a Si3N4 cap, whatever the nature of the buffer. Two explanations are proposed to account for this "cap effect" on clusters morphology: the first one is based on a calculation of the H /D minimizing the surface free energy of the clusters embedded between the buffer and the cap; the second one holds on the shape relaxation of the coalesced nonequilibrium clusters towards their equilibrium shape with the buffer, this process occurring until clusters are fully covered with the cap. Because of the higher deposition rate of Si3N4 compared to BN, a Si3N4 cap would allow a less efficient reshaping and consequently lead to flatter clusters. This explanation is supported by the temporal evolution of clusters morphology and repartition observed during the time delay before deposition of the cap. The evolution of the spectral position of the surface-plasmon resonance (SPR) of the trilayers as a function of their structure has also been investigated by optical transmittance measurements. The influence of cluster morphology, as well as the nature of the buffer and the cap on the SPR spectral position are discussed.

  17. Investigation of the asymmetric misfit dislocation morphology in epitaxial layers with the zinc-blende structure

    NASA Technical Reports Server (NTRS)

    Fox, Bradley A.; Jesser, William A.

    1990-01-01

    The source of the asymmetry in the dislocation morphology exhibited in the epitaxial growth of compound semiconductors on (100) was investigated. A thickness wedge of p- and n-type GaAs(0.95)P(0.05) was grown on GaAs by metalorganic chemical vapor deposition, and the effect of misorientation on the resolved shear stress for each slip system was calculated and eliminated as the source of the asymmetry. Another potential source of asymmetry, the thickness gradient, was also eliminated. Results show that the substrate misorientation and the thickness gradient do not significantly contribute to the asymmetry and that the dominant contributor to the asymmetry of misfit dislocations in the (001) epitaxial interface can be attributed to the differences in the Peierls barriers between the two types of dilocations in GaAsP/GaAs.

  18. Self-assembly Columnar Structure in Active Layer of Bulk Heterojunction Solar Cell

    NASA Astrophysics Data System (ADS)

    Pan, Cheng; Segui, Jennifer; Yu, Yingjie; Li, Hongfei; Akgun, Bulent; Satijia, Sushil. K.; Gersappe, Dilip; Nam, Chang-Yong; Rafailovich, Miriam

    2012-02-01

    Bulk Heterojunction (BHJ) polymer solar cells are an area of intense interest due to their flexibility and relatively low cost. However, due to the disordered inner structure in active layer, the power conversion efficiency of BHJ solar cell is relatively low. Our research provides the method to produce ordered self-assembly columnar structure within active layer of bulk heterojunction (BHJ) solar cell by introducing polystyrene (PS) into the active layer. The blend thin film of polystyrene, poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) at different ratio are spin coated on substrate and annealed in vacuum oven for certain time. Atomic force microscopy (AFM) images show uniform phase segregation on the surface of polymer blend thin film and highly ordered columnar structure is then proven by etching the film with ion sputtering. TEM cross-section technology is also used to investigate the column structure. Neutron reflectometry was taken to establish the confinement of PCBM at the interface of PS and P3HT. The different morphological structures formed via phase segregation will be correlated with the performance of the PEV cells to be fabricated at the BNL-CFN.

  19. How does the flow within the boundary layer influence morphological stability of a vicinal face?

    NASA Astrophysics Data System (ADS)

    Chernov, A. A.

    1992-04-01

    Imagine parallel growth steps forming a vacinal face and moving in the same direction. Since the diffusion fields of these steps overlap, the steps decelerate one another and spontaneously form macroscopic bunches. Such instability is known always to develop in supersaturated solutions and supercooled melts despite capillarity. The corresponding stability problems were analyzed previously with the assumption that the fuid within the boundary layer is stagnant. In this paper, the effect of solution flow within the boundary layer on the stability is considered for the first time. The analytical solution found describes the drift of diffusion clouds (enriched or improverished regions of solution) surrounding spontaneously appearing slight step bunches. This drift turns out to enhance instability if the fluid flow direction is the same as the step motion direction. However, if these directions are antiparallel, the drift is a very strong stabilizing factor which keeps the interface stable up to large (many cm) size. This stability is provided by the drift, in cooperation with the growth rate anisotropy. For isotropic growth kinetics, this flow-kinetic stabilization is absent. The flow-kinetic stabilization is several orders of magnitude stronger than the stabilization by capillarity. In solutions, very low flow rates, just exceeding the step growth rates, are sufficient for the stabilization. In melts, the step motion is very fast and is equivalent to the opposite fluid flow thus providing kinetic stabilization per se. The analytical solution obtained may be used in other crystal growth problems.

  20. Morphological features of the copper surface layer under sliding with high density electric current

    NASA Astrophysics Data System (ADS)

    Fadin, V. V.; Aleutdinova, M. I.; Rubtsov, V. Ye.; Aleutdinova, V. A.

    2015-10-01

    Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm2 are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.

  1. Morphological features of the copper surface layer under sliding with high density electric current

    SciTech Connect

    Fadin, V. V.; Aleutdinova, M. I.; Rubtsov, V. Ye.; Aleutdinova, V. A.

    2015-10-27

    Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm{sup 2} are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.

  2. Surface activation of CNT Webs towards layer by layer assembly of biosensors.

    PubMed

    Musameh, Mustafa; Huynh, Chi P; Hickey, Mark; Kyratzis, Ilias Louis

    2016-04-25

    Several surface activation methods such as chemical, electrochemical and plasma have been used for enhancing the electrochemical performance of carbon based electrodes for various applications. However, some of these surface activation methods may not be useful depending on the chemical and physical properties of the activated surface. Herein we investigate the surface activation of carbon nanotube (CNT) webs by electrochemical and plasma techniques to enhance their electrochemical performance and enable the fabrication of a biosensor using the layer-by-layer (LBL) approach. The pretreated CNT webs were characterized by SEM, TEM, Raman, XPS and electrochemical methods. TEM images and Raman analysis showed an increase in the level of surface defects upon pretreatment with higher number of defects after electrochemical pretreatment. XPS analysis showed an increase in the level of oxygen functional groups after pretreatment (4 to 5 times increase) which resulted in enhanced water wettability especially for plasma pretreated CNT webs. The pretreated CNT web electrodes also showed an enhanced electrochemical activity towards the oxidation and reduction of different redox probes with higher sensitivity for the electrochemically pretreated CNT web electrode that was accompanied by a higher level of noise in amperometric measurements. A highly linear response was obtained for the untreated and the electrochemically pretreated CNT web electrodes towards the amperometric detection of NADH (R(2) of 0.9996 and 0.9986 respectively) while a non-linear response was observed for the plasma pretreated CNT web electrode (R(2) of 0.8538). The pretreated CNT web electrodes enabled the fabrication of a LBL biosensor for alcohol detection with highest operational stability obtained for the plasma pretreated CNT web surface.

  3. Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: linking biofouling layer morphology with flux stabilization.

    PubMed

    Akhondi, Ebrahim; Wu, Bing; Sun, Shuyang; Marxer, Brigit; Lim, Weikang; Gu, Jun; Liu, Linbo; Burkhardt, Michael; McDougald, Diane; Pronk, Wouter; Fane, Anthony G

    2015-03-01

    In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range of 3.6 L/m(2) h (21 ± 1 °C, 40 mbar) to 7.3 L/m(2) h (29 ± 1 °C, 100 mbar) after slight fluctuations and remained constant for the duration of the experiments (almost 3 months). An increase in biofouling layer thickness and a variable biofouling layer structure were observed over time by optical coherence tomography and confocal laser scanning microscopy. The presence of eukaryotic organisms in the biofouling layer was observed by light microscopy and the microbial community structure of the biofouling layer was analyzed by sequences of 16S rRNA genes. The magnitude of permeate flux was associated with the combined effect of the biofouling layer thickness and structure. Changes in the biofouling layer structure were attributed to (1) the movement and predation behaviour of the eukaryotic organisms which increased the heterogeneous nature of the biofouling layer; (2) the bacterial debris generated by eukaryotic predation activity which reduced porosity; (3) significant shifts of the dominant bacterial species over time that may have influenced the biofouling layer structure. As expected, most of the particles and colloids in the feed seawater were removed by the GDM process, which led to a lower RO fouling potential. However, the dissolved organic carbon in the

  4. Cux1 and Cux2 regulate dendritic branching, spine morphology and synapses of the upper layer neurons of the cortex

    PubMed Central

    Cubelos, Beatriz; Sebastián-Serrano, Alvaro; Beccari, Leonardo; Calcagnotto, Maria Elisa; Cisneros, Elsa; Kim, Seonhee; Dopazo, Ana; Alvarez-Dolado, Manuel; Redondo, Juan Miguel; Bovolenta, Paola; Walsh, Christopher A.; Nieto, Marta

    2010-01-01

    Summary Dendrite branching and spine formation determines the function of morphologically distinct and specialized neuronal subclasses. However, little is known about the programs instructing specific branching patterns in vertebrate neurons and whether such programs influence dendritic spines and synapses. Using knockout and knockdown studies combined with morphological, molecular and electrophysiological analysis we show that the homeobox Cux1 and Cux2 are intrinsic and complementary regulators of dendrite branching, spine development and synapse formation in layer II–III neurons of the cerebral cortex. Cux genes control the number and maturation of dendritic spines partly through direct regulation of the expression of Xlr3b and Xlr4b, chromatin remodeling genes previously implicated in cognitive defects. Accordingly, abnormal dendrites and synapses in Cux2−/− mice correlate with reduced synaptic function and defects in working memory. These demonstrate critical roles of Cux in dendritogenesis and highlight novel subclass-specific mechanisms of synapse regulation that contribute to the establishment of cognitive circuits. PMID:20510857

  5. Morphologies developed by the drying of droplets containing dispersed and aggregated layered double hydroxide platelets.

    PubMed

    Zhang, Yan; Evans, Julian R G

    2013-04-01

    Despite much interest in the structures formed from droplets of suspension as they dry, there are few studies involving plate-like particles. Layered double hydroxide suspensions were prepared with pH adjusted to give well-dispersed and flocculated variants that were characterised by sedimentation and rheology measurements. In the well-dispersed suspension, the three-phase boundary was pinned and radial flow created a peripheral wall. The platelet structure involved local flat packing but was replete with scrolls that result from the recirculation flows in the droplets as they dry. In contrast, the flocculating suspension produced flatter droplet relics and the microstructure consisted of ordered domains which were disoriented with respect to each other. Although of scientific interest, the control of these structures will make it possible to use direct ink-jet printing to build 3D shapes for the preparation of aligned, ordered nanocomposites based on plate-like particles in which platelet preferred orientation mimics the structures found in nacre.

  6. Changes in morphology and optical properties of sclera and choroidal layers due to hyperosmotic agent.

    PubMed

    Zaman, Raiyan T; Rajaram, Narasimhan; Nichols, Brandon S; Rylander, Henry G; Wang, Tianyi; Tunnell, James W; Welch, Ashley J

    2011-07-01

    Light scattering in the normally white sclera prevents diagnostic imaging or delivery of a focused laser beam to a target in the underlying choroid layer. In this study, we examine optical clearing of the sclera and changes in blood flow resulting from the application of glycerol to the sclera of rabbits. Recovery dynamics are monitored after the application of saline. The speed of clearing for injection delivery is compared to the direct application of glycerol through an incision in the conjunctiva. Although, the same volume of glycerol was applied, the sclera cleared much faster (5 to 10 s) with the topical application of glycerol compared to the injection method (3 min). In addition, the direct topical application of glycerol spreads over a larger area in the sclera than the latter method. A diffuse optical spectroscopy system provided spectral analysis of the remitted light every two minutes during clearing and rehydration. Comparison of measurements to those obtained from phantoms with various absorption and scattering properties provided estimates of the absorption coefficient and reduced scattering coefficient of rabbit eye tissue. PMID:21806288

  7. Changes in morphology and optical properties of sclera and choroidal layers due to hyperosmotic agent

    NASA Astrophysics Data System (ADS)

    Zaman, Raiyan T.; Rajaram, Narasimhan; Nichols, Brandon S.; Rylander, Henry G.; Wang, Tianyi; Tunnell, James W.; Welch, Ashley J.

    2011-07-01

    Light scattering in the normally white sclera prevents diagnostic imaging or delivery of a focused laser beam to a target in the underlying choroid layer. In this study, we examine optical clearing of the sclera and changes in blood flow resulting from the application of glycerol to the sclera of rabbits. Recovery dynamics are monitored after the application of saline. The speed of clearing for injection delivery is compared to the direct application of glycerol through an incision in the conjunctiva. Although, the same volume of glycerol was applied, the sclera cleared much faster (5 to 10 s) with the topical application of glycerol compared to the injection method (3 min). In addition, the direct topical application of glycerol spreads over a larger area in the sclera than the latter method. A diffuse optical spectroscopy system provided spectral analysis of the remitted light every two minutes during clearing and rehydration. Comparison of measurements to those obtained from phantoms with various absorption and scattering properties provided estimates of the absorption coefficient and reduced scattering coefficient of rabbit eye tissue.

  8. Adjustment of the summertime marine atmospheric boundary layer to the western Iberia coastal morphology

    NASA Astrophysics Data System (ADS)

    Monteiro, Isabel T.; Santos, Aires J.; Belo-Pereira, Margarida; Oliveira, Paulo B.

    2016-04-01

    During summer (June, July, and August), northerly winds driven by the Azores anticyclone are prevalent over western Iberia. The Quick Scatterometer Satellite 2000 to 2009 summertime estimates reveal a broad high wind speed (≥7 ms-1) area extending about 300 km from shore and along the entire Iberian west coast. Nested in this large high-speed region, preferred maximum regions anchored in the Iberian major capes, Finisterre, Roca, and S. Vicente, are found. Composite analyses of wind maxima were performed to diagnose the typical summertime synoptic-scale pressure distribution associated with these smaller size high-speed regions. The flow low-level structure was further studied with a mesoscale numerical prediction model for three northerly events characterized by typical summertime synoptic conditions. A low-level coastal jet, setting the background conditions to the marine atmospheric boundary layer (MABL) response to topography, was found in the three cases. The causes for wind maximum downwind capes were investigated, focusing on the hypothesis that western Iberia MABL responds to hydraulic forcing. For the three events supercritical and transcritical flow conditions were identified and expansion fan signatures were found downwind each cape. Aircraft measurements, performed during one of the events, gave additional evidence of the expansion fan leeward Cape Roca. The importance of other forcing mechanisms was also assessed by considering the hypothesis of downslope wind acceleration and found to be in direct conflict with soundings and surface observations.

  9. Preparation of three-layered porous PLA/PEG scaffold: relationship between morphology, mechanical behavior and cell permeability.

    PubMed

    Scaffaro, R; Lopresti, F; Botta, L; Rigogliuso, S; Ghersi, G

    2016-02-01

    Interface tissue engineering (ITE) is used to repair or regenerate interface living tissue such as for instance bone and cartilage. This kind of tissues present natural different properties from a biological and mechanical point of view. With the aim to imitating the natural gradient occurring in the bone-cartilage tissue, several technologies and methods have been proposed over recent years in order to develop polymeric functionally graded scaffolds (FGS). In this study three-layered scaffolds with a pore size gradient were developed by melt mixing polylactic acid (PLA) and two water-soluble porogen agents: sodium chloride (NaCl) and polyethylene glycol (PEG). Pore dimensions were controlled by NaCl granulometry while PEG solvation created a micropores network within the devices. Scaffolds were characterized from a morphological and mechanical point of view in order to find a correlation between the preparation method, the pore architecture and compressive mechanical behavior. Biological tests were also performed in order to study the effect of pore size gradient on the permeation of different cell lines in co-culture. To imitate the physiological work condition, compressive tests were also performed in phosphate buffered saline (PBS) solution at 37°C. The presented preparation method permitted to prepare three-layered scaffolds with high control of porosity and pore size distribution. Furthermore mechanical behaviors were found to be strongly affected by pore architecture of tested devices as well as the permeation of osteoblast and fibroblast in-vitro. PMID:26410761

  10. Preparation of three-layered porous PLA/PEG scaffold: relationship between morphology, mechanical behavior and cell permeability.

    PubMed

    Scaffaro, R; Lopresti, F; Botta, L; Rigogliuso, S; Ghersi, G

    2016-02-01

    Interface tissue engineering (ITE) is used to repair or regenerate interface living tissue such as for instance bone and cartilage. This kind of tissues present natural different properties from a biological and mechanical point of view. With the aim to imitating the natural gradient occurring in the bone-cartilage tissue, several technologies and methods have been proposed over recent years in order to develop polymeric functionally graded scaffolds (FGS). In this study three-layered scaffolds with a pore size gradient were developed by melt mixing polylactic acid (PLA) and two water-soluble porogen agents: sodium chloride (NaCl) and polyethylene glycol (PEG). Pore dimensions were controlled by NaCl granulometry while PEG solvation created a micropores network within the devices. Scaffolds were characterized from a morphological and mechanical point of view in order to find a correlation between the preparation method, the pore architecture and compressive mechanical behavior. Biological tests were also performed in order to study the effect of pore size gradient on the permeation of different cell lines in co-culture. To imitate the physiological work condition, compressive tests were also performed in phosphate buffered saline (PBS) solution at 37°C. The presented preparation method permitted to prepare three-layered scaffolds with high control of porosity and pore size distribution. Furthermore mechanical behaviors were found to be strongly affected by pore architecture of tested devices as well as the permeation of osteoblast and fibroblast in-vitro.

  11. Experiments on the active control of transitional boundary layers

    NASA Astrophysics Data System (ADS)

    Nelson, P. A.; Rioual, J.-L.; Fisher, M. J.

    Experimental results are presented which demonstrate that the streamwise position of the transition region of a flat plate boundary layer can be actively controlled. The means of control is through the application of suction through the surface of the plate, a progressive increase in suction rate being capable of producing transition at progressively larger distances downstream from the plate leading edge. A simple digital feedback regulator based on an integral control law is shown to be most effective in regulating the position of transition, an error signal being derived from measurements of pressure fluctuations on the surface of the plate.

  12. Mineralogy, morphology and stratigraphy of the light-toned interior layered deposits at Juventae Chasma

    NASA Astrophysics Data System (ADS)

    Noel, Alicia; Bishop, Janice L.; Al-Samir, Muna; Gross, Christoph; Flahaut, Jessica; McGuire, Patrick C.; Weitz, Catherine M.; Seelos, Frank; Murchie, Scott

    2015-05-01

    Juventae Chasma is a deep depression located north of Valles Marineris on Mars, with four bright mounds or light-toned interior layered deposits (ILDs) extending upwards from the Canyon floor. We present here the results of long-term imaging of Juventae Chasma including mounds A, B, C, and D using multiple datasets. Monohydrated sulfates (MHS) were deposited first on the canyon floor, followed by polyhydrated sulfates (PHS). The upper PHS-dominated units are largely eroded away at Juventae Chasma, but this material is still present in significant abundance at mound B. PHS are observed mixed with MHS in some areas of mounds A and C. Terraces are observed at the upper elevations of mound B that contain PHS at the steeper slopes and appear to be covered with dust on the horizontal surfaces. Current analyses of the MHS-rich unit indicate that kieserite (MgSO4ṡH2O) is the primary sulfate component, rather than szomolnokite (FeSO4ṡH2O) as previously thought. Formation of kieserite at Juventae Chasma likely required temperatures in the 150-200 °C range. Geochemical modeling is most consistent with dissolution of mafic materials followed by precipitation of kieserite from solution. The dust exhibits ferric signatures and the sand is largely mafic material. Outcrops of olivine- and pyroxene-bearing rocks are best observed along the base of mound C and in the chaotic terrain surrounding mound D. This study summarizes the current understanding of Juventae Chasma and its ILDs using HRSC, HiRISE and CTX data, an expanded laboratory spectral library, and the latest calibrations available for CRISM.

  13. Atomic layer deposition encapsulated activated carbon electrodes for high voltage stable supercapacitors.

    PubMed

    Hong, Kijoo; Cho, Moonkyu; Kim, Sang Ouk

    2015-01-28

    Operating voltage enhancement is an effective route for high energy density supercapacitors. Unfortunately, widely used activated carbon electrode generally suffers from poor electrochemical stability over 2.5 V. Here we present atomic layer deposition (ALD) encapsulation of activated carbons for high voltage stable supercapacitors. Two-nanometer-thick Al2O3 dielectric layers are conformally coated at activated carbon surface by ALD, well-maintaining microporous morphology. Resultant electrodes exhibit excellent stability at 3 V operation with 39% energy density enhancement from 2.5 V operation. Because of the protection of surface functional groups and reduction of electrolyte degradation, 74% of initial voltage was maintained 50 h after full charge, and 88% of capacitance was retained after 5000 cycles at 70 °C accelerated test, which correspond to 31 and 17% improvements from bare activated carbon, respectively. This ALD-based surface modification offers a general method to enhance electrochemical stability of carbon materials for diverse energy and environmental applications.

  14. Stratigraphy and Morphology of Drumlins within the Múlajökull Active Drumlin Field, Iceland

    NASA Astrophysics Data System (ADS)

    Benediktsson, I. O.; Jonsson, S. A.; Schomacker, A.; Johnson, M. D.; Ingolfsson, O.

    2014-12-01

    Our current understanding of drumlin formation is largely based on investigations of individual drumlins either within Pleistocene drumlin fields or within the forefields of contemporary glaciers, showing variable composition and structure resulting in different models for drumlin genesis. The stratigraphy and morphology of drumlins within the active drumlin field at the Múlajökull surge-type piedmont glacier, Iceland, have been studied in order to shed light on their formation. A total of 110 drumlins where mapped and measured and their internal stratigraphy and composition were documented in three exposures. The exposures all revealed several till units where the youngest till truncates the older ones on the flanks of the drumlins and at the proximal side. A geomorphological study shows that drumlins within the 1992 surge end moraine are relatively long and narrow whilst drumlins further away from the current ice margin are wider and slightly shorter. Three models are proposed to explain the stratigraphy and morphological evolution of the drumlins within the Múlajökull drumlin field. Firstly, we suggest that radial crevasses in the glacier terminus lead to spatial differences in normal pressure at the base so that deposition is favoured beneath and erosion in between the crevasses and, consequently, the crevasse pattern of the glacier controls the location of the drumlins. Secondly, sediment accumulating beneath the crevasses acts as an obstacle to the ice, which decreases the ice flow and facilitates sedimentation. Simultaneously and subsequently, the accumulation of sediments is shaped by the ice flow into a drumlin. Thirdly we conclude that the drumlins are evolving from being wide and low to in the distal part to narrow and high in the proximal part. The drumlins are then maintained and their relief increases as the glacier erodes the sides and the proximal end of the drumlin and drapes new till layer over the landform.

  15. Optical activity of transparent polymer layers characterized by spectral means

    NASA Astrophysics Data System (ADS)

    Cosutchi, Andreea Irina; Dimitriu, Dan Gheorghe; Zelinschi, Carmen Beatrice; Breaban, Iuliana; Dorohoi, Dana Ortansa

    2015-06-01

    The method based on the channeled spectrum, validated for inorganic optical active layers, is used now to determine the optical activity of some transparent polymer solutions in different solvents. The circular birefringence, the dispersion parameter and the specific rotation were estimated in the visible range by using the measurements of wavelengths in the channeled spectra of Hydroxypropyl cellulose in water, methanol and acetic acid. The experiments showed the specific rotation dependence on the polymer concentration and also on the solvent nature. The decrease of the specific rotation in the visible range with the increase in wavelength was evidenced. The method has some advantages as the rapidity of the experiments and the large spectral range in which it can be applied. One disadvantage is the fact that the channeled spectrum does not allow to establish the rotation sense of the electric field intensity.

  16. Effect of pore morphology on the electrochemical properties of electric double layer carbon cryogel supercapacitors

    NASA Astrophysics Data System (ADS)

    Batalla García, Betzaida; Feaver, Aaron M.; Zhang, Qifeng; Champion, Richard D.; Cao, Guozhong; Fister, Tim T.; Nagle, Ken P.; Seidler, Gerald T.

    2008-07-01

    In this study, a group of carbon cryogels have been synthesized using resorcinol formaldehyde as precursors, and altered via catalysis and activation, to obtain varied nanostructures and pore size distributions. To understand the relation between structure and electrochemical properties, an alternate approach to de Levi's cylindrical pore, transmission line method was utilized. Using electrochemical impedance spectroscopy, the capacitor can be studied as a dielectric system composed of a porous electrode and the electrolyte (tetraethylammonium tetrafluoroborate in propylene carbonate). The complex capacitance and power are used to study the behavior of the system below the relaxation frequency f0 (φ=-45°). Therefore, the relaxation of the capacitor system at the low frequency range, f

  17. Locomotor activity influences muscle architecture and bone growth but not muscle attachment site morphology

    PubMed Central

    Rabey, Karyne N.; Green, David J.; Taylor, Andrea B.; Begun, David R.; Richmond, Brian G.; McFarlin, Shannon C.

    2014-01-01

    The ability to make behavioural inferences from skeletal remains is critical to understanding the lifestyles and activities of past human populations and extinct animals. Muscle attachment site (enthesis) morphology has long been assumed to reflect muscle strength and activity during life, but little experimental evidence exists to directly link activity patterns with muscle development and the morphology of their attachments to the skeleton. We used a mouse model to experimentally test how the level and type of activity influences forelimb muscle architecture of spinodeltoideus, acromiodeltoideus, and superficial pectoralis, bone growth rate and gross morphology of their insertion sites. Over an 11-week period, we collected data on activity levels in one control group and two experimental activity groups (running, climbing) of female wild-type mice. Our results show that both activity type and level increased bone growth rates influenced muscle architecture, including differences in potential muscular excursion (fibre length) and potential force production (physiological cross-sectional area). However, despite significant influences on muscle architecture and bone development, activity had no observable effect on enthesis morphology. These results suggest that the gross morphology of entheses is less reliable than internal bone structure for making inferences about an individual’s past behaviour. PMID:25467113

  18. Morphological effects of lipopeptides against Aspergillus fumigatus correlate with activities against (1,3)-beta-D-glucan synthase.

    PubMed Central

    Kurtz, M B; Heath, I B; Marrinan, J; Dreikorn, S; Onishi, J; Douglas, C

    1994-01-01

    The lipopeptide antifungal agents, echinocandins, papulacandins, and pneumocandins, kill Candida albicans by inhibiting glucan synthesis. For this fungus, there is a good correlation of in vitro enzyme inhibition with in vitro assays of MICs. Semisynthetic lipopeptides such as cilofungin, LY303366, L-693,989, and L-733,560 have activity in vivo against Aspergillus infections but appear to be inactive in broth dilution in vitro tests (MICs, > 128 micrograms/ml). To understand how compounds which lack activity in vitro can have good in vivo activity, we monitored the effect of pneumocandins on the morphology of Aspergillus fumigatus and A, flavus strains by light microscopy and electron microscopy and related the changes in growth to inhibition of glucan synthesis. Pneumocandin B0 caused profound changes in hyphal growth; light micrographs showed abnormally swollen germ tubes, highly branched hyphal tips, and many cells with distended balloon shapes. Aspergillus electron micrographs confirmed that lipopeptides produce changes in cell walls; drug-treated germlings showed very stubby growth with thick walls and a conspicuous dark outer layer which was much thicker in the subapical regions. The rest of the hyphal tip ultrastructure was unaffected by the drug, indicating considerable specificity for the primary target. The drug-induced growth alteration produced very compact clumps in broth dilution wells, making it possible to score the morphological effect macroscopically. The morphological changes could be assayed quantitatively by using conventional broth microdilution susceptibility assay conditions. We defined the endpoint as the lowest concentration required to produce the morphological effect and called it the minimum effective concentration to distinguish it from the no-growth endpoints used in MIC determinations. The minimum effective concentration assay was related to inhibition of glucan synthase activity in vitro and may provide a starting point for

  19. Active Flow Control on a Boundary-Layer-Ingesting Inlet

    NASA Technical Reports Server (NTRS)

    Gorton, Susan Althoff; Owens, Lewis R.; Jenkins, Luther N.; Allan, Brian G.; Schuster, Ernest P.

    2004-01-01

    Boundary layer ingestion (BLI) is explored as means to improve overall system performance for Blended Wing Body configuration. The benefits of BLI for vehicle system performance benefit are assessed with a process derived from first principles suitable for highly-integrated propulsion systems. This performance evaluation process provides framework within which to assess the benefits of an integrated BLI inlet and lays the groundwork for higher-fidelity systems studies. The results of the system study show that BLI provides a significant improvement in vehicle performance if the inlet distortion can be controlled, thus encouraging the pursuit of active flow control (AFC) as a BLI enabling technology. The effectiveness of active flow control in reducing engine inlet distortion was assessed using a 6% scale model of a 30% BLI offset, diffusing inlet. The experiment was conducted in the NASA Langley Basic Aerodynamics Research Tunnel with a model inlet designed specifically for this type of testing. High mass flow pulsing actuators provided the active flow control. Measurements were made of the onset boundary layer, the duct surface static pressures, and the mass flow through the duct and the actuators. The distortion was determined by 120 total pressure measurements located at the aerodynamic interface plane. The test matrix was limited to a maximum freestream Mach number of 0.15 with scaled mass flows through the inlet for that condition. The data show that the pulsed actuation can reduce distortion from 29% to 4.6% as measured by the circumferential distortion descriptor DC60 using less than 1% of inlet mass flow. Closed loop control of the actuation was also demonstrated using a sidewall surface static pressure as the response sensor.

  20. Morphology, composition, age and spatial extent of a layered superficial formation covering the plains around Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Le Deit, L.; Bourgeois, O.; Le Mouélic, S.; Quantin-Nataf, C.; Mège, D.; Sotin, C.; Massé, M.; Sarago, V.

    2008-09-01

    Introduction An extensive light-toned layered formation covers the plains surrounding Valles Marineris on Mars. It is particularly visible south of Ius Chasma and of Melas Chasma [1], southwest of Juventae Chasma [2,3], north of Tithonium Chasma and west of Ganges Chasma. Some deposits of this formation may be enriched in hydrated silicates such as hydrated glasses, chalcedony, opal or other hydrated Si-rich phases according to CRISM data [1]. From an analysis of HRSC, THEMIS, MOC, HiRISE, MOLA PEDR, OMEGA and CRISM data, we discuss the morphology, the composition, the age, the spatial extent and the emplacement processes of these layered deposits (LDs). Here we focus on two regions where the LDs are particularly spectacular: Ganges Chasma and Juventae Chasma. Regional map We have compiled a regional map of the LDs around Valles Marineris (orange in Fig. 1a). In some cases their spatial extent is unclear due to their being covered either by dark material or by dust that appears yellow on IRB color HiRISE images (Fig 1b). Dashed contours on Fig. 1a outline these poorly constrained boundaries, whereas plain contours correspond to regions where the stratigraphic contact between the LDs and the underlying basement is unambiguous. The light-toned LDs are located stratigraphically and topographically above the basaltic basement that constitutes the plains surrounding Valles Marineris. The total thickness of the LDs does not exceed a hundred meters on average. They consist of subparallel light-toned layers of various thicknesses that are apparently interbedded with darker beds (Fig. 1b). This difference in albedo can be due to variations in mineralogical composition, topographic slope, roughness, grain size or state of erosion of the different layers, or to partial covering of certain layers by a dark mantle. Ganges Chasma West of Ganges Chasma, the LDs rest topographically and stratigraphically above the Noachian plains that have been defined as the Npl2 unit [4] (Fig. 1

  1. Active Morphology Control for Concomitant Long Distance Spin Transport and Photoresponse in a Single Organic Device.

    PubMed

    Sun, Xiangnan; Bedoya-Pinto, Amilcar; Mao, Zupan; Gobbi, Marco; Yan, Wenjing; Guo, Yunlong; Atxabal, Ainhoa; Llopis, Roger; Yu, Gui; Liu, Yunqi; Chuvilin, Andrey; Casanova, Felix; Hueso, Luis E

    2016-04-01

    Long distance spin transport and photoresponse are demonstrated in a single F16 CuPc spin valve. By introducing a low-temperature strategy for controlling the morphology of the organic layer during the fabrication of a molecular spin valve, a large spin-diffusion length up to 180 nm is achieved at room temperature. Magnetoresistive and photoresponsive signals are simultaneously observed even in an air atmosphere. PMID:26823157

  2. Characterization of cathode keeper wear by surface layer activation

    NASA Technical Reports Server (NTRS)

    Polk, James E.

    2003-01-01

    In this study, the erosion rates of the discharge cathode keeper in a 30 cm NSTAR configuration ion thruster were measured using a technique known as Surface Layer Activation (SLA). This diagnostic technique involves producing a radioactive tracer in a given surface by bombardment with high energy ions. The decrease in activity of the tracer material may be monitored as the surface is subjected to wear processes and correlated to a depth calibration curve, yielding the eroded depth. Analysis of the activities was achieved through a gamma spectroscopy system. The primary objectives of this investigation were to reproduce erosion data observed in previous wear studies in order to validate the technique, and to determine the effect of different engine operating parameters on erosion rate. The erosion profile at the TH 15 (23 kw) setting observed during the 8200 hour Life Demonstration Test (LDT) was reproduced. The maximum keeper erosion rate at this setting was determined to be 0.085 pm/hr. Testing at the TH 8 (1.4 kw) setting demonstrated lower erosion rates than TH 15, along with a different wear profile. Varying the keeper voltage was shown to have a significant effect on the erosion, with a positive bias with respect to cathode potential decreasing the erosion rate significantly. Accurate measurements were achieved after operating times of only 40 to 70 hours, a significant improvement over other erosion diagnostic methods.

  3. Organic matrix morphology and distribution in the palisade layer of eggshells sampled at selected periods during lay.

    PubMed

    Fraser, A C; Bain, M M; Solomon, S E

    1998-05-01

    1. 1 cm2 pieces of eggshells from a commercial battery flock were plasma etched to remove the outer shell membranes. 2. They were decalcified using EDTA (200 g/l, pH 6.9 to 7.0) in paraformaldehyde (20 g/l) and 25% gluteraldehyde (20 ml in 0.98 l) in phosphate buffer, then prepared for light and transmission electron microscopy. 3. Light microscopy revealed a differential distribution of matrix material within all 3 regions of the palisade layer at the beginning of lay. 4. Transmission electron microscopy revealed a more even distribution of matrix at the beginning of lay, although morphological differences were observed. At the end of lay all 3 regions showed an increase in % matrix and vesicles/10 cm2 of micrograph compared to the middle and beginning of lay periods. 5. It is hypothesised that matrix vesicles are involved in the regulation of the physiochemical environment within the forming eggshell and that the decline in shell quality associated with the end of lay is related to a concomitant change in matrix quality.

  4. Morphology, star formation, and nuclear activity in void galaxies

    NASA Astrophysics Data System (ADS)

    Wiedmann, Sophia; Miller, Brendan; Gallo, Elena; Pazar, Beni; Alfvin, Erik

    2015-01-01

    We report on new Chandra observations of six early-type galaxies located within cosmic voids, from a program examining the influence of Mpc-scale environment upon star formation and low-level supermassive black hole activity. Simple feedback prescriptions are predicted to operate independently of the surrounding density once outside the dark matter halo, and further link star formation quenching to black hole activity. Alternatively, mediation of the cold gas supply by the large-scale environment, for example through increased cold-stream accretion and reduced harassment or stripping within more isolated regions, could mutually enhance star formation and (perhaps indirectly) low-level supermassive black hole activity. The six targeted early-type galaxies have comparable stellar masses of 6-9e10 solar, chosen to be near the predicted "critical value" for efficient feedback, but span a wide range of star-formation rates. Specifically, they have SFRs of 6.5, 1.4, 0.45, 0.10, 0.04, and 0.03 solar masses per year. All galaxies are detected in the Chandra ACIS-S observations with 0.3-8 keV X-ray luminosities ranging from 2e39 to 1e41 erg/s. Specifically, they have log Lx values of 40.4, 41.1, 41.1, 39.3, 39.2, and 39.2, again ordered by decreasing SFR. The three galaxies with moderate-to-high star formation rates have nuclear X-ray luminosities that are significantly greater than those of the three galaxies with low star formation rates. This result is more consistent with a symbiotic relationship between current low-level star formation and supermassive black hole activity than with simple feedback quenching models. We additionally situate these galaxies in the context of void and cluster galaxies in the local universe, model their optical surface brightness profiles and color gradients, discuss caveats including the possibility of X-ray binary contamination, and consider other supermassive black hole activity indicators.

  5. Activity-dependent regulation of synapse and dendritic spine morphology in developing barrel cortex requires phospholipase C-beta1 signalling.

    PubMed

    Spires, Tara L; Molnár, Zoltán; Kind, Peter C; Cordery, Patricia M; Upton, A Louise; Blakemore, Colin; Hannan, Anthony J

    2005-04-01

    The phospholipase C-beta1 (PLC-beta1) signalling pathway, activated via metabotropic glutamate receptors (mGluRs), is implicated in activity-dependent development of the cerebral cortex, as both PLC-beta1 and mGluR5 knockout mice exhibit disrupted barrel formation in somatosensory cortex. To characterize the effects of this signalling system on development of synaptic circuitry in barrel cortex, we have examined neuronal ultrastructure, synapse formation and dendritic spine morphology in PLC-beta1 knockout mice. Qualitative ultrastructure of neurons and synapse density in layers 2-4 of barrel cortex were unchanged in PLC-beta1 knockout mice during development [postnatal day (P) 5] and in mature cortex (P19-21). We found a decrease in the proportion of synapses with symmetric morphology at P5 that was gone by P19-21, indicating a transient imbalance in excitatory and inhibitory circuitry. We also investigated dendritic spines by back-labelling layer 5 pyramidal neurons with carbocyanine. We observed normal dendritic spine densities on apical dendrites as they passed through layer 4 of barrel cortex, but spine morphology was altered in PLC-beta1 knockout mice at P9. These observations indicate that the PLC-beta1 signalling pathway plays a role in the development of normal cortical circuitry. Interrupting this regulation leads to changes in synapse and dendritic spine morphology, possibly altering post-synaptic integration of signal.

  6. Effect of solvents on morphology and photocatalytic activity of BiOBr synthesized by solvothermal method

    SciTech Connect

    Liu, ZhangSheng; Wu, BianTao; Xiang, DongHu; Zhu, YaBo

    2012-11-15

    Graphical abstract: Display Omitted Highlight: ► BiOBr photocatalysts with various morphologies were synthesized. ► The choice of organic solvents was first extended to glycerol. ► Morphologies are greatly dependant on the solvent used. ► GR-mediated BiOBr has the highest photocatalytic activity. -- Abstract: BiOBr photocatalysts with various morphologies have been synthesized via a solvothermal method in ethanol-, ethylene glycol (EG)- and glycerol (GR)-mediated conditions, respectively. The effects of different solvents on the size and morphology of BiOBr crystal are investigated in detail. Viscosity of the solvents is believed to be a key factor in determining morphology of BiOBr crystal, which leads to the different formation mechanisms. In addition, it is found that the photocatalytic activities of BiOBr samples for the degradation of methyl orange (MO) under visible light irradiation are dependent on the solvent used in the synthesis. The differences in the photocatalytic activities are mainly attributed to the different morphologies, which further results in the difference in Brunauer–Emmett–Teller (BET) surface areas, bandgaps, the exposed crystal facets and porous structures.

  7. Spectroelectrochemical evidence for the effect of phase structure and interface on charge behavior in poly(3-hexylthiophene): Fullerene active layer

    NASA Astrophysics Data System (ADS)

    Hu, Rong; Ni, Haitao; Wang, Zhaodong; Liu, Yurong; Liu, Hongdong; Yang, Xin; Cheng, Jiang

    2016-09-01

    To investigate the correlation between morphology of active layer and performance of polymer solar cells (PSCs). Poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) were selected as research object and five PSCs based on active layers with varied morphology were fabricated. The results showed that P3HT crystalline phase and donor-acceptor (D-A) interface had an important influence on PSCs performance, which was revealed by structure characterization and J-V measurement. To further understanding the effect of phase structure and D-A interface on charge behavior. Spectroelectrochemistry measurement (SEC) was performed to characterize the steady-state optical absorption of P3HT, PCBM cation and anion in varied active layers, and the spectra difference of cations and anions was analyzed. The results were found that D-A interface could promote charge generation. P3HT crystalline phase and PCBM aggregation phase were beneficial for improving the charge transport ability. Meanwhile, the non-equilibrium transport of electron and hole in PSCs was corroborated by SEC.

  8. Improved performance of polymer solar cells using PBDTT-F-TT:PC71BM blend film as active layer

    NASA Astrophysics Data System (ADS)

    Zang, Yue; Gao, Xiumin; Lu, Xinmiao; Xin, Qing; Lin, Jun; Zhao, Jufeng

    2016-07-01

    A detailed study of high-efficiency polymer solar cells (PSCs) based on a low bandgap polymer PBDTT-F-TT and PC71BM as the bulk heterojunction (BHJ) layer is carried out. By using 1,8-diiodooctane (DIO) as solvent additive to control the morphology of active layer and comparing different device architecture to optimize the optical field distribution, the power conversion efficiency (PCE) of the resulted devices can be reached as high as 9.34%. Comprehensive characterization and optical modeling of the resulting devices is performed to understand the effect of DIO and device geometry on photovoltaic performance. It was found that the addition of DIO can significantly improve the nanoscale morphology and increased electron mobility in the BHJ layer. The inverted device architecture was chosen because the results from optical modeling shows that it offers better optical field distribution and exciton generation profile. Based on these results, a low-temperature processed ZnO was finally introduced as an electron transport layer to facility the fabrication on flexible substrates and showed comparable performance with the device based on conventional ZnO interlayer prepared by sol-gel process.

  9. Novel biohybrids of layered double hydroxide and lactate dehydrogenase enzyme: Synthesis, characterization and catalytic activity studies

    NASA Astrophysics Data System (ADS)

    Djebbi, Mohamed Amine; Braiek, Mohamed; Hidouri, Slah; Namour, Philippe; Jaffrezic-Renault, Nicole; Ben Haj Amara, Abdesslem

    2016-02-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biomolecule such as enzyme to produce bioinorganic system. Lactate dehydrogenase (Lac Deh) has been chosen as a model enzyme, being immobilized onto MgAl and ZnAl LDH materials via direct ion-exchange (adsorption) and co-precipitation methods. The immobilization efficiency was largely dependent upon the immobilization methods. A comparative study shows that the co-precipitation method favors the immobilization of great and tunable amount of enzyme. The structural behavior, chemical bonding composition and morphology of the resulting biohybrids were determined by X-ray diffraction (XRD) study, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM), respectively. The free and immobilized enzyme activity and kinetic parameters were also reported using UV-Visible spectroscopy. However, the modified LDH materials showed a decrease in crystallinity as compared to the unmodified LDH. The change in activity of the immobilized lactate dehydrogenase was considered to be due, to the reduced accessibility of substrate molecules to the active sites of the enzyme and the partial conformational change of the Lac Deh molecules as a result of the immobilization way. Finally, it was proven that there is a correlation between structure/microstructure and enzyme activity dependent on the immobilization process.

  10. Antibacterial activity of silver nanoparticles with different morphologies as well as their possible antibacterial mechanism

    NASA Astrophysics Data System (ADS)

    Hu, Guansong; Jin, Wenxiu; Chen, Qingyuan; Cai, Yuchun; Zhu, Qiuhua; Zhang, Wanzhong

    2016-10-01

    Silver nanoparticles (AgNPs) have good antibacterial activity and their morphologies have important influence on their activity. The relationship between their bactericidal property and morphology has not been studied thoroughly. Silver triangular nanoplates have basic {111} surface, nanospheres and nanocubes mainly have {100} planes, and nanorods have {100} side surfaces and {111} end facets. It was said that {111} crystal plane of AgNPs may play a prime role in antibacterial progress. Moreover, the antibacterial activity of nanocubes is not very clear when compared to nanoparticles with other morphologies. In this paper, we studied the antibacterial activity of nanocubes and attempted to confirm whether nanoparticles with {111} crystal facet truly had stronger antibacterial activity than other nanoparticles. We prepared four kinds of AgNPs and found silver triangle nanoplates had the best antibacterial activity, while nanospheres, nanocubes and short nanorods showed similar efficacy. It may provide a reference for safe application of AgNPs with different morphologies in the medical field.

  11. Induction and modulation of persistent activity in a layer V PFC microcircuit model

    PubMed Central

    Papoutsi, Athanasia; Sidiropoulou, Kyriaki; Cutsuridis, Vassilis; Poirazi, Panayiota

    2013-01-01

    Working memory refers to the temporary storage of information and is strongly associated with the prefrontal cortex (PFC). Persistent activity of cortical neurons, namely the activity that persists beyond the stimulus presentation, is considered the cellular correlate of working memory. Although past studies suggested that this type of activity is characteristic of large scale networks, recent experimental evidence imply that small, tightly interconnected clusters of neurons in the cortex may support similar functionalities. However, very little is known about the biophysical mechanisms giving rise to persistent activity in small-sized microcircuits in the PFC. Here, we present a detailed biophysically—yet morphologically simplified—microcircuit model of layer V PFC neurons that incorporates connectivity constraints and is validated against a multitude of experimental data. We show that (a) a small-sized network can exhibit persistent activity under realistic stimulus conditions. (b) Its emergence depends strongly on the interplay of dADP, NMDA, and GABAB currents. (c) Although increases in stimulus duration increase the probability of persistent activity induction, variability in the stimulus firing frequency does not consistently influence it. (d) Modulation of ionic conductances (Ih, ID, IsAHP, IcaL, IcaN, IcaR) differentially controls persistent activity properties in a location dependent manner. These findings suggest that modulation of the microcircuit's firing characteristics is achieved primarily through changes in its intrinsic mechanism makeup, supporting the hypothesis of multiple bi-stable units in the PFC. Overall, the model generates a number of experimentally testable predictions that may lead to a better understanding of the biophysical mechanisms of persistent activity induction and modulation in the PFC. PMID:24130519

  12. Towards NOAA Forecasts of Permafrost Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Livezey, M. M.; Jonassen, R. G.; Horsfall, F. M. C.; Jafarov, E. E.; Schaefer, K. M.

    2014-12-01

    NOAA's implementation of its 2014 Arctic Action Plan (AAP) lacks services related to permafrost change yet the Interagency Working Group on Coordination of Domestic Energy Development and Permitting in Alaska noted that warming permafrost challenges land-based development and calls for agencies to provide focused information needed by decision-makers. To address this we propose to link NOAA's existing seasonal forecasts of temperature and precipitation with a high-resolution model of the thermal state of permafrost (Jafarov et al., 2012) to provide near-term (one year ahead) forecasts of active layer thickness (ALT). Such forecasts would be an official NOAA statement of the expected thermal state of permafrost ALT in Alaska and would require: (1) long-term climate outlooks, (2) a permafrost model, (3) detailed specification of local spatial and vertical controls upon soil thermal state, (4) high-resolution vertical measurements of that thermal state, and (5) demonstration of forecast skill in pilot studies. Pilot efforts should focus on oil pipelines where the cost can be justified. With skillful forecasts, engineers could reduce costs of monitoring and repair as well as ecosystem damage by positioning equipment to more rapidly respond to predicted disruptions.

  13. Active Layer Soil Carbon and Nutrient Mineralization, Barrow, Alaska, 2012

    DOE Data Explorer

    Stan D. Wullschleger; Holly M. Vander Stel; Colleen Iversen; Victoria L. Sloan; Richard J. Norby; Mallory P. Ladd; Jason K. Keller; Ariane Jong; Joanne Childs; Deanne J. Brice

    2015-10-29

    This data set consists of bulk soil characteristics as well as carbon and nutrient mineralization rates of active layer soils manually collected from the field in August, 2012, frozen, and then thawed and incubated across a range of temperatures in the laboratory for 28 day periods in 2013-2015. The soils were collected from four replicate polygons in each of the four Areas (A, B, C, and D) of Intensive Site 1 at the Next-Generation Ecosystem Experiments (NGEE) Arctic site near Barrow, Alaska. Soil samples were coincident with the established Vegetation Plots that are located in center, edge, and trough microtopography in each polygon. Data included are 1) bulk soil characteristics including carbon, nitrogen, gravimetric water content, bulk density, and pH in 5-cm depth increments and also by soil horizon, 2) carbon, nitrogen, and phosphorus mineralization rates for soil horizons incubated aerobically (and in one case both aerobically and anaerobically) for 28 days at temperatures that included 2, 4, 8, and 12 degrees C. Additional soil and incubation data are forthcoming. They will be available when published as part of another paper that includes additional replicate analyses.

  14. Active millimeter wave detection of concealed layers of dielectric material

    NASA Astrophysics Data System (ADS)

    Bowring, N. J.; Baker, J. G.; Rezgui, N. D.; Southgate, M.; Alder, J. F.

    2007-04-01

    Extensive work has been published on millimetre wave active and passive detection and imaging of metallic objects concealed under clothing. We propose and demonstrate a technique for revealing the depth as well as the outline of partially transparent objects, which is especially suited to imaging layer materials such as explosives and drugs. The technique uses a focussed and scanned FMCW source, swept through many GHz to reveal this structure. The principle involved is that a parallel sided dielectric slab produces reflections at both its upper and lower surfaces, acting as a Fabry-Perot interferometer. This produces a pattern of alternating reflected peaks and troughs in frequency space. Fourier or Burg transforming this pattern into z-space generates a peak at the thickness of the irradiated sample. It could be argued that though such a technique may work for single uniform slabs of dielectric material, it will give results of little or no significance when the sample both scatters the incident radiation and gives erratic reflectivities due to its non-uniform thickness and permittivity . We show results for a variety of materials such as explosive simulants, powder and drugs, both alone and concealed under clothing or in a rucksack, which display strongly directional reflectivities at millimeter wavelengths, and whose location is well displayed by a varying thickness parameter as the millimetre beam is scanned across the target. With this system we find that samples can easily be detected at standoff distances of at least 4.6m.

  15. Active layer hydrology for Imnavait Creek, Toolik, Alaska

    SciTech Connect

    Hinzman, L.D.; Kane, D.L.

    1987-04-01

    The hydrology of the active layer of a watershed is described. In the annual hydrologic cycle, snowmelt is the most significant event at Imnavait Creek located near Toolik Lake, Alaska. Precipitation that has accumulated for more than 6 months on the surface melts in a relatively short period of 7 to 10 days once sustained melting occurs. Significant runoff events are few. Convective storms covering relatively small areas on the North Slope of Alaska can produce significant small-scale events in a small watershed scale,but these events are rapidly attenuated outside the basin. Data collection began in August 1984. We have continuously monitored the hydrologic, the meteorologic, and the soil`s physical conditions. Information was collected through implementation of four snowmelt runoff plots and measurements of essential microclimate parameters. Soil moisture and temperature profiles were measured adjacent to each snowmelt runoff plot, and heat flux is collected adjacent to one of these plots. Meteorological parameters were measured locally. The water content of the snowpack prior to snowmelt was measured throughout the watershed and measured daily adjacent to each plot during snowmelt. The stream draining the basin was measured regularly during the spring melt event to provide information on watershed runoff rates and the volume of snowmelt.

  16. Active layer hydrology for Imnavait Creek, Toolik, Alaska

    SciTech Connect

    Hinzman, L.D.; Kane, D.L.

    1987-04-01

    The hydrology of the active layer of a watershed is described. In the annual hydrologic cycle, snowmelt is the most significant event at Imnavait Creek located near Toolik Lake, Alaska. Precipitation that has accumulated for more than 6 months on the surface melts in a relatively short period of 7 to 10 days once sustained melting occurs. Significant runoff events are few. Convective storms covering relatively small areas on the North Slope of Alaska can produce significant small-scale events in a small watershed scale,but these events are rapidly attenuated outside the basin. Data collection began in August 1984. We have continuously monitored the hydrologic, the meteorologic, and the soil's physical conditions. Information was collected through implementation of four snowmelt runoff plots and measurements of essential microclimate parameters. Soil moisture and temperature profiles were measured adjacent to each snowmelt runoff plot, and heat flux is collected adjacent to one of these plots. Meteorological parameters were measured locally. The water content of the snowpack prior to snowmelt was measured throughout the watershed and measured daily adjacent to each plot during snowmelt. The stream draining the basin was measured regularly during the spring melt event to provide information on watershed runoff rates and the volume of snowmelt.

  17. Effects of Soil Property Uncertainty on Projected Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Harp, D. R.; Atchley, A. L.; Coon, E.; Painter, S. L.; Wilson, C. J.; Romanovsky, V. E.; Liljedahl, A.

    2014-12-01

    Uncertainty in future climate is often assumed to contribute the largest uncertainty to active layer thickness (ALT) projections. However, the impact of soil property uncertainty on these projections may be significant. In this research, we evaluate the contribution of soil property uncertainty on ALT projections at the Barrow Environmental Observatory, Alaska. The effect of variations in porosity, thermal conductivity, saturation, and water retention properties of peat and mineral soil are evaluated. The micro-topography of ice wedge polygons present at the site is included in the analysis using three 1D column models to represent polygon center, rim and trough features. The Arctic Terrestrial Simulator (ATS) is used to model multiphase thermal and hydrological processes in the subsurface. We apply the Null-Space Monte Carlo (NSMC) algorithm to identify an ensemble of soil property combinations that produce simulated temperature profiles that are consistent with temperature measurements available from the site. ALT is simulated for the ensemble of soil property combinations for four climate scenarios. The uncertainty in ALT due to soil properties within and across climate scenarios is evaluated. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and Environmental Research in the DOE Office of Science.

  18. Improved surface morphology of stacked 1.3 μm InAs/GaAs quantum dot active regions by introducing annealing processes

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Tatebayashi, Jun; Nishioka, Masao; Arakawa, Yasuhiko

    2006-08-01

    The authors report a simple but effective way to improve the surface morphology of stacked 1.3μm InAs /GaAs quantum dot (QD) active regions grown by metal-organic chemical vapor deposition (MOCVD), in which GaAs middle spacer and top separate confining heterostructure (SCH) layers are deposited at a low temperature of 560°C to suppress postgrowth annealing effect that can blueshift emission wavelength of QDs. By introducing annealing processes just after depositing the GaAs spacer layers, the authors demonstrate that the surface morphology of the top GaAs SCH layer can be dramatically improved. For a model structure of five-layer QDs, the surface roughness with the introduced annealing processes (IAPs) is reduced to about 1.3nm (5×5μm2 area), much less than 4.2nm without the IAPs. Furthermore, photoluminescence measurements show that inserting the annealing steps does not induce any changes in emission wavelength. This dramatic improvement in surface morphology results from the improved GaAs spacer surfaces due to the IAPs. The technique reported here has important implications for realizing stacked 1.3μm InAs /GaAs QD lasers based on MOCVD.

  19. Engineering the Morphology and Configuration of Ternary Heterostructures for Improving Their Photocatalytic Activity.

    PubMed

    Li, Kui; Chen, Rong; Li, Shun-Li; Xie, Shuai-Lei; Cao, Xue-Li; Dong, Long-Zhang; Bao, Jian-Chun; Lan, Ya-Qian

    2016-02-01

    Heteronanomaterials composed of suitable semiconductors enable the direct conversion from solar power into clean and renewable energy. Ternary heterostructures with appropriate configuration and morphology possess rich and varied properties, especially for improving the photocatalytic activity and stability synchronously. However, suitable ternary heterostructure prototypes and facile while effective strategy for modulating their morphology and configuration are still scarce. Herein, various ternary ZnS-CdS-Zn(1-x)Cd(x)S heterostructures with tunable morphology (0 to 2 D) and semiconductor configurations (randomly distributed, interface mediated, and quantum dots sensitized core@shell heterostructures) were facilely synthesized via one-pot hydrothermal method resulting from the different molecular structures of the amine solvents. Semiconductor morphology, especially configuration of the ternary heterostructure, shows dramatic effect on their photocatalytic activity. The CdS sensitized porous Zn(1-x)CdxS@ZnS core@shell takes full advantage of ZnS, Zn(1-x)Cd(x)S and CdS and shows the maximal photocatalytic H2-production rate of 100.2 mmol/h/g and excellent stability over 30 h. This study provides some guidelines for the design and synthesis of high-performance ternary heterostructure via modulation of semiconductor configuration and morphology using one-pot method.

  20. Engineering the Morphology and Configuration of Ternary Heterostructures for Improving Their Photocatalytic Activity.

    PubMed

    Li, Kui; Chen, Rong; Li, Shun-Li; Xie, Shuai-Lei; Cao, Xue-Li; Dong, Long-Zhang; Bao, Jian-Chun; Lan, Ya-Qian

    2016-02-01

    Heteronanomaterials composed of suitable semiconductors enable the direct conversion from solar power into clean and renewable energy. Ternary heterostructures with appropriate configuration and morphology possess rich and varied properties, especially for improving the photocatalytic activity and stability synchronously. However, suitable ternary heterostructure prototypes and facile while effective strategy for modulating their morphology and configuration are still scarce. Herein, various ternary ZnS-CdS-Zn(1-x)Cd(x)S heterostructures with tunable morphology (0 to 2 D) and semiconductor configurations (randomly distributed, interface mediated, and quantum dots sensitized core@shell heterostructures) were facilely synthesized via one-pot hydrothermal method resulting from the different molecular structures of the amine solvents. Semiconductor morphology, especially configuration of the ternary heterostructure, shows dramatic effect on their photocatalytic activity. The CdS sensitized porous Zn(1-x)CdxS@ZnS core@shell takes full advantage of ZnS, Zn(1-x)Cd(x)S and CdS and shows the maximal photocatalytic H2-production rate of 100.2 mmol/h/g and excellent stability over 30 h. This study provides some guidelines for the design and synthesis of high-performance ternary heterostructure via modulation of semiconductor configuration and morphology using one-pot method. PMID:26835705

  1. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  2. Nanosecond laser-induced selective removal of the active layer of CuInGaSe2 solar cells by stress-assisted ablation

    NASA Astrophysics Data System (ADS)

    Buzás, András; Geretovszky, Zsolt

    2012-06-01

    We demonstrate that laser pulses of nanosecond duration (λ=1064 nm, τ=25 ns, PRR =5 kHz) are capable of the clean removal of the CuInGaSe2 (CIGS) and ZnO:Al layers in the layer structure of chalcogenide-based solar cells, leaving the underlying Mo layer undamaged and producing excellent crater morphology. Our results prove that the material removal process is governed by the thermomechanical stress developing in the CIGS layer due to rapid laser heating. In the mechanical ablation of the active layer, three phenomena play a crucial role, namely, delamination, buckling, and fracture. Morphological and compositional analysis of the laser-processed areas is used to identify the experimental parameters where clean mechanical ablation can be achieved. Numerical calculations, performed in the comsol software environment, are also presented to complement the experimental tendencies and verify the proposed model. Our calculation proves the development of a stress distribution that drives the delamination of the CIGS and Mo layers. As the delamination front proceeds radially outward, the separation of the layers ceases in the colder outer regions according to the Griffith's criterion and defines the size of the craters produced afterwards. The free-standing chalcogenide layer continues to deform, and buckling results in a growing tensile stress at the perimeter of the delaminated area, where ultimately fracture will finalize the removal process and facilitate the clean ablation of the laser-irradiated area.

  3. Long-Term Global Morphology of Gravity Wave Activity Using UARS Data

    NASA Technical Reports Server (NTRS)

    Eckermann, Stephen D.; Bacmeister, Julio T.; Wu, Dong L.

    1998-01-01

    Progress in research into the global morphology of gravity wave activity using UARS data is described for the period March-June, 1998. Highlights this quarter include further progress in the analysis and interpretation of CRISTA temperature variances; model-generated climatologies of mesospheric gravity wave activity using the HWM-93 wind and temperature model; and modeling of gravity wave detection from space-based platforms. Preliminary interpretations and recommended avenues for further analysis are also described.

  4. Photocatalytic activity of ZNO with different morphologies synthesized by a sonochemical method

    NASA Astrophysics Data System (ADS)

    Phuruangrat, Anukorn; Yayapao, Oranuch; Thongtem, Somchai; Thongtem, Titipun

    2016-05-01

    Different morphologies of ZnO structures were successfully synthesized in precursor solutions with the pH of 8, 9, 10, 11, and 12 by a sonochemical method at room temperature. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) and Raman spectroscopy. The photocatalytic activities of ZnO samples with different morphologies were evaluated via the degradation of methylene blue (C16H18ClN3S). In this research, the flower-like ZnO sample of densely assembled nanoplates exhibited the highest photodegradation of 64% under UV light irradiation within 300 min.

  5. Morphological analysis of activity-reduced adult-born neurons in the mouse olfactory bulb.

    PubMed

    Dahlen, Jeffrey E; Jimenez, Daniel A; Gerkin, Richard C; Urban, Nathan N

    2011-01-01

    Adult-born neurons (ABNs) are added to the olfactory bulb (OB) throughout life in rodents. While many factors have been identified as regulating the survival and integration of ABNs into existing circuitry, the understanding of how these factors affect ABN morphology and connectivity is limited. Here we compare how cell intrinsic [small interfering RNA (siRNA) knock-down of voltage gated sodium channels Na(V)1.1-1.3] and circuit level (naris occlusion) reductions in activity affect ABN morphology during integration into the OB. We found that both manipulations reduce the number of dendritic spines (and thus likely the number of reciprocal synaptic connections) formed with the surrounding circuitry and inhibited dendritic ramification of ABNs. Further, we identified regions of ABN apical dendrites where the largest and most significant decreases occur following siRNA knock-down or naris occlusion. In siRNA knock-down cells, reduction of spines is observed in proximal regions of the apical dendrite. This suggests that distal regions of the dendrite may remain active independent of Na(V)1.1-1.3 channel expression, perhaps facilitated by activation of T-type calcium channels and NMDA receptors. By contrast, circuit level reduction of activity by naris occlusion resulted in a global depression of spine number. Together, these results indicate that ABNs retain the ability to develop their typical overall morphological features regardless of experienced activity, and activity modulates the number and location of formed connections.

  6. Putative role of border cells in generating spontaneous morphological activity within Kölliker's organ.

    PubMed

    Dayaratne, M W Nishani; Vlajkovic, Srdjan M; Lipski, Janusz; Thorne, Peter R

    2015-12-01

    Kölliker's organ is a transient epithelial structure, comprising a major part of the organ of Corti during pre-hearing stages of development. The auditory system is spontaneously active during development, which serves to retain and refine neural connections. Kölliker's organ is considered a key candidate for generating such spontaneous activity, most likely through purinergic (P2 receptor) signalling and inner hair cell (IHC) activation. Associated with the spontaneous neural activity, ATP released locally by epithelial cells induces rhythmic morphological changes within Kölliker's organ, the purpose of which is not understood. These changes are accompanied by a shift in cellular refractive index, allowing optical detection of this activity in real-time. Using this principle, we investigated the origin of spontaneous morphological activity within Kölliker's organ. Apical turns of Wistar rat cochleae (P9-11) were dissected, and the purinergic involvement was studied following acute tissue exposure to a P2 receptor agonist (ATPγS) and antagonist (suramin). ATPγS induced a sustained darkening throughout Kölliker's organ, reversed by suramin. This effect was most pronounced in the region closest to the inner hair cells, which also displayed the highest frequency of intrinsic morphological events. Additionally, suramin alone induced swelling of this region, suggesting a tight regulation of cell volume by ATP-mediated mechanisms. Histological analysis of cochlear tissues demonstrates the most profound volume changes in the border cell region immediately adjacent to the IHCs. Together, these results underline the role of purinergic signalling in initiating morphological events within Kölliker's organ, and suggest a key involvement of border cells surrounding IHCs in regulating this spontaneous activity.

  7. Microglia in mouse retina contralateral to experimental glaucoma exhibit multiple signs of activation in all retinal layers

    PubMed Central

    2014-01-01

    Background Glaucomatous optic neuropathy, a leading cause of blindness, can progress despite control of intraocular pressure - currently the main risk factor and target for treatment. Glaucoma progression shares mechanisms with neurodegenerative disease, including microglia activation. In the present model of ocular hypertension (OHT), we have recently described morphological signs of retinal microglia activation and MHC-II upregulation in both the untreated contralateral eyes and OHT eyes. By using immunostaining, we sought to analyze and quantify additional signs of microglia activation and differences depending on the retinal layer. Methods Two groups of adult Swiss mice were used: age-matched control (naïve, n = 12), and lasered (n = 12). In the lasered animals, both OHT eyes and contralateral eyes were analyzed. Retinal whole-mounts were immunostained with antibodies against Iba-1, MHC-II, CD68, CD86, and Ym1. The Iba-1+ cell number in the plexiform layers (PL) and the photoreceptor outer segment (OS), Iba-1+ arbor area in the PL, and area of the retina occupied by Iba-1+ cells in the nerve fiber layer-ganglion cell layer (NFL-GCL) were quantified. Results The main findings in contralateral eyes and OHT eyes were: i) ameboid microglia in the NFL-GCL and OS; ii) the retraction of processes in all retinal layers; iii) a higher level of branching in PL and in the OS; iv) soma displacement to the nearest cell layers in the PL and OS; v) the reorientation of processes in the OS; vi) MHC-II upregulation in all retinal layers; vii) increased CD68 immunostaining; and viii) CD86 immunolabeling in ameboid cells. In comparison with the control group, a significant increase in the microglial number in the PL, OS, and in the area occupied by Iba-1+ cells in the NFL-GCL, and significant reduction of the arbor area in the PL. In addition, rounded Iba-1+ CD86+ cells in the NFL-GCL, OS and Ym1+ cells, and rod-like microglia in the NFL-GCL were restricted to OHT eyes

  8. Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano

    NASA Astrophysics Data System (ADS)

    Thal, Janis; Tivey, Maurice; Yoerger, Dana R.; Bach, Wolfgang

    2016-09-01

    North Su is a double-peaked active andesite submarine volcano located in the eastern Manus Basin of the Bismarck Sea that reaches a depth of 1154 m. It hosts a vigorous and varied hydrothermal system with black and white smoker vents along with several areas of diffuse venting and deposits of native sulfur. Geologic mapping based on ROV observations from 2006 and 2011 combined with morphologic features identified from repeated bathymetric surveys in 2002 and 2011 documents the emplacement of a volcanic cryptodome between 2006 and 2011. We use our observations and rock analyses to interpret an eruption scenario where highly viscous, crystal-rich andesitic magma erupted slowly into the water-saturated, gravel-dominated slope of North Su. An intense fragmentation process produced abundant blocky clasts of a heterogeneous magma (olivine crystals within a rhyolitic groundmass) that only rarely breached through the clastic cover onto the seafloor. Phreatic and phreatomagmatic explosions beneath the seafloor cause mixing of juvenile and pre-existing lithic clasts and produce a volcaniclastic deposit. This volcaniclastic deposit consists of blocky, non-altered clasts next, variably (1-100%) altered clasts, hydrothermal precipitates and crystal fragments. The usually applied parameters to identify juvenile subaqueous lava fragments, i.e. fluidal shape or chilled margin, were not applicable to distinguish between pre-existing non-altered clasts and juvenile clasts. This deposit is updomed during further injection of magma and mechanical disruption. Gas-propelled turbulent clast-recycling causes clasts to develop variably rounded shapes. An abundance of blocky clasts and the lack of clasts typical for the contact of liquid lava with water is interpreted to be the result of a cooled, high-viscosity, crystal-rich magma that failed as a brittle solid upon stress. The high viscosity allows the lava to form blocky and short lobes. The pervasive volcaniclastic cover on North Su is

  9. Tuning photocatalytic activity of In2S3 broadband spectrum photocatalyst based on morphology

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Liu, Wenxia; Gao, Wenwen

    2016-04-01

    Efficient utilization of full solar light especially near-infrared light (NIR) is still a great challenge. Herein three In2S3 nanomaterials with cubic phase and different morphologies were synthesized via hydrothermal methods by using sodium sulfide (Na2S), thiosemicarbazide (TSC) and thioacetamide (TAA) as sulfur sources, respectively. All the as-synthesized In2S3 samples were found to be photo-active under either UV, visible or NIR light irradiation although they possess very different morphologies. The In2S3 sample with irregular and plate-like nanoparticles synthesized by using Na2S as sulfur source shows the highest activity on photodegradation of methyl orange due to its exposure of more photoactive (311) plane than the other two In2S3 samples and the occurrence of lattice oxygen. The samples that synthesized by using TSC and TAA as sulfur sources possess the morphology of hollow microspheres, which are hierarchically constructed by thinner nanosheets and cumulated by thicker platelets, respectively. The microsphere sample constructed by thinner nanosheets shows even lower photocatalytic activity than that accumulated by thicker platelets under all the tested light regions especially under longer irradiation time because of its less exposed (311) plane and lower sulfur vacancies although it possesses a far larger specific surface area than the latter. These results suggest that the exposure of more photoactive (311) plane and occurrence of lattice oxygen deserve more attention to improve the photocatalytic activity of In2S3.

  10. Photocatalytic and antibacterial activity of cadmium sulphide/zinc oxide nanocomposite with varied morphology.

    PubMed

    Jana, T K; Maji, S K; Pal, A; Maiti, R P; Dolai, T K; Chatterjee, K

    2016-10-15

    Nanocomposites with multifunctional application prospects have already dragged accelerating interests of materials scientists. Here we present CdS/ZnO nanocomposites with different morphology engineering the precursor molar ratio in a facile wet chemical synthesis route. The materials were structurally and morphologically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX) and high-resolution transmission electron microscopy (HRTEM). The growth mechanism of the composite structure with varying molar ratio is delineated with oriented attachment self assemble techniques. Photocatalytic activity of CdS/ZnO nanocomposites with varying morphology were explored for the degradation of rhodamine B (RhB) dye in presence of visible light irradiation and the results reveal that the best catalytic performance arises in CdS/ZnO composite with 1: 1 ratio. The antibacterial efficiency of all nanocomposites were investigated on Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia without light irradiation. Antibacterial activity of CdS/ZnO nanocomposites were studied using the bacteriological test-well diffusion agar method and results showed significant antibacterial activity in CdS/ZnO composite with 1:3 ratio. Overall, CdS/ZnO nanocomposites excel in different potential applications, such as visible light photocatalysis and antimicrobial activity with their tuneable structure.

  11. In situ derivation of sulfur activated TiO{sub 2} nano porous layers through pulse-micro arc oxidation technology

    SciTech Connect

    Bayati, M.R.; Golestani-Fard, F.; Moshfegh, A.Z.; Molaei, Roya

    2011-10-15

    Highlights: {yields} S-TiO{sub 2} layers were grown by MAO technique under pulse current for the first time. {yields} Effect of growth parameters on chemical composition, topography, and morphology of the layers was studied. {yields} A correlation between photocatalytic performance and growth conditions was proposed. -- Abstract: Micro arc oxidation technique, as a facile and efficient process, was employed to grow sulfur doped titania porous layers. This research sheds light on the photocatalytic performance of the micro arc oxidized S-TiO{sub 2} nano-porous layers fabricated under pulse current. Morphological and topographical studies, performed by SEM and AFM techniques, revealed that increasing the frequency and/or decreasing the duty cycle resulted in formation of finer pores and smoother surfaces. XRD and XPS results showed that the layers consisted of anatase and rutile phases whose fraction was observed to change depending on the synthesis conditions. The highest anatase relative content was obtained at the frequency of 500 Hz and the duty cycle of 5%. Furthermore, photocatalytic activity of the layers was examined by measuring the decomposition rate of methylene blue under both ultraviolet and visible photo irradiations. Maximum photodegradation reaction rate constants over the pulse-grown S-TiO{sub 2} layers were respectively measured as 0.0202 and 0.0110 min{sup -1} for ultraviolet and visible irradiations.

  12. Effects of spatial variation of skull and cerebrospinal fluid layers on optical mapping of brain activities

    NASA Astrophysics Data System (ADS)

    Wang, Shuping; Shibahara, Nanae; Kuramashi, Daishi; Okawa, Shinpei; Kakuta, Naoto; Okada, Eiji; Maki, Atsushi; Yamada, Yukio

    2010-07-01

    In order to investigate the effects of anatomical variation in human heads on the optical mapping of brain activity, we perform simulations of optical mapping by solving the photon diffusion equation for layered-models simulating human heads using the finite element method (FEM). Particularly, the effects of the spatial variations in the thicknesses of the skull and cerebrospinal fluid (CSF) layers on mapping images are investigated. Mapping images of single active regions in the gray matter layer are affected by the spatial variations in the skull and CSF layer thicknesses, although the effects are smaller than those of the positions of the active region relative to the data points. The increase in the skull thickness decreases the sensitivity of the images to active regions, while the increase in the CSF layer thickness increases the sensitivity in general. The images of multiple active regions are also influenced by their positions relative to the data points and by their depths from the skin surface.

  13. Layer-by-layer engineered nanocapsules of curcumin with improved cell activity.

    PubMed

    Kittitheeranun, Paveenuch; Sajomsang, Warayuth; Phanpee, Sarunya; Treetong, Alongkot; Wutikhun, Tuksadon; Suktham, Kunat; Puttipipatkhachorn, Satit; Ruktanonchai, Uracha Rungsardthong

    2015-08-15

    Nanocarriers based on electrostatic Layer-by-layer (LbL) assembly of CaCO3 nanoparticles (CaCO3 NPs) was investigated. These inorganic nanoparticles was used as templates to construct nanocapsules made from films based on two oppositely charged polyelectrolytes, poly(diallyldimethylammonium chloride), and poly (sodium 4-styrene-sulfonate sodium salt), followed by core dissolution. The naked CaCO3 NPs, CaCO3 NPs coated with the polyelectrolytes and hollow nanocapsules were found with hexagonal shape with average sizes of 350-400 nm. A reversal of the surface charge between positive to negative zeta potential values was found, confirming the adsorption of polyelectrolytes. The loading efficiency and release of curcumin were controlled by the hydrophobic interactions between the drug and the polyelectrolyte matrix of the hollow nanocapsules. The quantity of curcumin released from hollow nanocapsules was found to increase under acidic environments, which is a desirable for anti-cancer drug delivery. The hollow nanocapsules were found to localize in the cytoplasm and nucleus compartment of Hela cancer cells after 24 h of incubation. Hollow nanocapsules were non-toxic to human fibroblast cells. Furthermore, curcumin loaded hollow nanocapsules exhibited higher in vitro cell inhibition against Hela cells than that of free curcumin, suggesting that polyelectrolyte based-hollow nanocapsules can be utilized as new carriers for drug delivery. PMID:26143232

  14. Direct impact of nonequilibrium aggregates on the structure and morphology of Pdadmac/SDS layers at the air/water interface.

    PubMed

    Campbell, Richard A; Yanez Arteta, Marianna; Angus-Smyth, Anna; Nylander, Tommy; Noskov, Boris A; Varga, Imre

    2014-07-29

    We discuss different nonequilibrium mechanisms by which bulk aggregates directly modify, and can even control, the interfacial structure and morphology of an oppositely charged polyelectrolyte/surfactant (P/S) mixture. Samples are categorized at the air/water interface with respect to the dynamic changes in the bulk phase behavior, the bulk composition, and the sample history using complementary surface-sensitive techniques. First, we show that bulk aggregates can spontaneously interact with the adsorption layer and are retained in it and that this process occurs most readily for positively charged aggregates with an expanded structure. In this case, key nonequilibrium issues of aggregate dissociation and spreading of surface-active material at the interface have a marked influence on the macroscopic interfacial properties. In a second distinct mechanism, aggregates inherently become trapped at the interface during its creation and lateral flocculation occurs. This irreversible process is most pronounced for aggregates with the lowest charge. A third mechanism involves the deposition of aggregates at interfaces due to their transport under gravity. The specificity of this process at an interface depends on its location and is mediated by density effects in the bulk. The prevalence of each mechanism critically depends on a number of different factors, which are outlined systematically here for the first time. This study highlights the sheer complexity by which aggregates can directly impact the interfacial properties of a P/S mixture. Our findings offer scope for understanding seemingly mysterious irreproducible effects which can compromise the performance of formulations in wide-ranging applications from foams to emulsions and lubricants.

  15. 2D double-layer-tube-shaped structure Bi2S3/ZnS heterojunction with enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Gao, Xiaoming; Wang, Zihang; Fu, Feng; Li, Xiang; Li, Wenhong

    2015-10-01

    Bi2S3/ZnS heterojunction with 2D double-layer-tube-shaped structures was prepared by the facile synthesis method. The corresponding relationship was obtained among loaded content to phase, morphology, and optical absorption property of Bi2S3/ZnS composite. The results shown that Bi2S3 loaded could evidently change the crystallinity of ZnS, enhance the optical absorption ability for visible light of ZnS, and improve the morphologies and microstructure of ZnS. The photocatalytic activities of the Bi2S3/ZnS sample were evaluated for the photodegradation of phenol and desulfurization of thiophene under visible light irradiation. The results showed that Bi2S3 loaded greatly improved the photocatalytic activity of ZnS, and the content of loaded Bi2S3 had an impact on the catalytic activity of ZnS. Moreover, the mechanism of enhanced photocatalytic activity was also investigated by analysis of relative band positions of Bi2S3 and ZnS, and photo-generated hole was main active radicals during photocatalytic oxidation process.

  16. Morphological and numerical analysis of synaptic interactions between neurons in deep and superficial layers of the entorhinal cortex of the rat.

    PubMed

    van Haeften, Theo; Baks-te-Bulte, Luciënne; Goede, Peter H; Wouterlood, Floris G; Witter, Menno P

    2003-01-01

    Neurons providing connections between the deep and superficial layers of the entorhinal cortex (EC) constitute a pivotal link in the network underlying reverberation and gating of neuronal activity in the entorhinal-hippocampal system. To learn more of these deep-to-superficial neurons and their targets, we applied the tracer Neurobiotin pericellularly in layer V of the medial EC of 12 rats. Labeled axons in the superficial layers were studied with light and electron microscopy, and their synaptic organization recorded. Neurobiotin-labeled layer V neurons displayed "Golgi-like" staining. Two major cell types were distinguished among these neurons: (1) pyramidal neurons with apical spiny dendrites traversing all layers and ramifying in layer I, and (2) horizontal neurons with dendrites confined to the deep layers. Labeled axons ramified profusely in layer III, superficially in layer II and deep in layer I. Analysis of labeled axon terminals in layers I-II and III showed that most synapses (95%) were asymmetrical. Of these synapses, 56% occurred with spines (presumably belonging to principal neurons) and 44% with dendritic shafts (presumably interneurons). A small fraction of the synapses (5%) was of the symmetrical type. Such synapses were mainly seen on dendritic shafts. We found in two sections a symmetrical synapse on a spine. These findings suggest that the deep to superficial projection is mainly excitatory in nature, and that these fibers subserve both excitation and feed-forward inhibition. There is an additional, much weaker, inhibitory component in this projection, which may have a disinhibitory effect on the entorhinal network in the superficial layers.

  17. Microscale X-ray tomographic investigation of the interfacial morphology between the catalyst and micro porous layers in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Prass, Sebastian; Hasanpour, Sadegh; Sow, Pradeep Kumar; Phillion, André B.; Mérida, Walter

    2016-07-01

    The interfacial morphology between the catalyst layer (CL) and micro porous layer (MPL) influences the performance of proton exchange membrane fuel cells (PEMFCs). Here we report a direct method to investigate the CL-MPL interfacial morphology of stacked and compressed gas diffusion layer (GDL with MPL)-catalyst coated membrane (CCM) assemblies. The area, origin and dimensions of interfacial gaps are studied with high-resolution X-ray micro computed tomography (X-μCT). The projected gap area (fraction of the CL-MPL interface separated by gaps) is higher for GDL-CCM assemblies with large differences in the surface roughness between CL and MPL but reduces with increasing compression and similarity in roughness. Relatively large continuous gaps are found in proximity to cracks in the MPL. These are hypothesized to form due to the presence of large pores on the surface of the GDL. Smaller gaps are induced by the surface roughness features throughout the CL-MPL interface. By modification of the pore sizes on the GDL surface serving as substrate for the MPL, the number and dimension of MPL crack induced gaps can be manipulated. Moreover, adjusting the CL and MPL surface roughness parameters to achieve similar orders of roughness can improve the surface mating characteristics of these two components.

  18. Comparison of submarine gully morphologies in passive and active margin settings

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Shumaker, L.; Johnstone, S.; Graham, S. A.

    2015-12-01

    Passive and active tectonic margins have inherently different hypsometry, due to local patterns of deformation and subsequent impacts on the style of sedimentation. One way we can analyze and compare the two settings is through observation of submarine gullies, which are small channel features that form along the continental slope as it descends to the ocean floor. By documenting the geometries of gullies that have formed on passive margins and gullies that have formed on active margins, we attempt to distinguish differences in gully morphologies in these two settings. We manually mapped over 600 gullies and interfluves from shaded relief and contour maps generated from bathymetric data across the globe, including the coast of California, the Beaufort Sea, and the Black Sea. We extrapolated and plotted elevation profiles of the gullies along their downslope distance, and compared a range of gully properties, such as length, spacing, and slope, to look at the correlations among those elements of gullies and their tectonic setting. We find that gullies forming on active margins show the greatest variability in their slopes, exhibiting both the steepest and the shallowest slopes of the dataset. The slopes of the passive margin gullies fall within the range of the active margin gully slopes, but interestingly, we note patterns in the ranges of gully steepness at different localities. These results differ from our our anticipation that active margin gullies are steeper than passive margin gullies, but suggest that gullies in all settings display a variety of morphologies. Additional mapping of active margin gullies will better determine if there are morphological differences between the two settings.

  19. High temperature microbial activity in upper soil layers.

    PubMed

    Santana, M M; Gonzalez, J M

    2015-11-01

    Biomineralization at high temperatures in upper soil layers has been largely ignored, although desertification and global warming have led to increasing areas of soils exposed to high temperatures. Recent publications evidenced thermophilic bacteria ubiquity in soils as viable cells, and their role in nutrient cycling and seedling development. High temperature events, frequently observed at medium and low latitudes, locate temporal niches for thermophiles to grow in soils. There, at temperatures inhibitory for common mesophiles, thermophilic bacteria could perform biogeochemical reactions important to the soil food web. Nutrient cycling analyses in soils at medium and low latitudes would benefit from considering the potential role of thermophiles.

  20. Voluntary exercise partially reverses neonatal alcohol-induced deficits in mPFC layer II/III dendritic morphology of male adolescent rats.

    PubMed

    Hamilton, G F; Criss, K J; Klintsova, A Y

    2015-08-01

    Developmental alcohol exposure in humans can produce a wide range of deficits collectively referred to as fetal alcohol spectrum disorders (FASD). FASD-related impairments in executive functioning later in life suggest long-term damage to the prefrontal cortex (PFC). In rodent neonates, moderate to high levels of alcohol exposure decreased frontal lobe brain size and altered medial PFC pyramidal neuron dendritic morphology. Previous research in our lab demonstrated that neonatal alcohol exposure decreased basilar dendritic complexity but did not affect spine density in Layer II/III pyramidal neurons in 26- to 30-day-old rats. The current study adds to the literature by evaluating the effect of neonatal alcohol exposure on mPFC Layer II/III basilar dendritic morphology in adolescent male rats. Additionally, it examines the potential for voluntary exercise to mitigate alcohol-induced deficits on mPFC dendritic complexity. An animal model of binge drinking during the third trimester of pregnancy was used. Rats were intubated with alcohol (alcohol-exposed, AE; 5.25 g kg(-1) day(-1)) on postnatal days (PD) 4-9; two control groups were included (suckle control and sham-intubated). Rats were anesthetized and perfused with heparinized saline solution on PD 42, and brains were processed for Golgi-Cox staining. Developmental alcohol exposure decreased spine density and dendritic complexity of basilar dendrites of Layer II/III neurons in the medial PFC (mPFC) compared to dendrites of control animals. Voluntary exercise increased spine density and dendritic length in AE animals resulting in elimination of the differences between AE and SH rats. Thus, voluntary exercise during early adolescence selectively rescued alcohol-induced morphological deficits in the mPFC. PMID:25967699

  1. Evidences of correlation between the DAN active mode measurements variability and local surface micro-morphology diversity along the rover Curiosity traverse in the Gale crater

    NASA Astrophysics Data System (ADS)

    Kuzmin, Ruslan

    The Dynamic Albedo of Neutrons (DAN) instrument has been operational second year since almost immediately after the landing of the Mars Science Laboratory (MSL) on August 6, 2012 at the bottom of Gale Crater. In the report we present the result of the DAN measurement analysis, accumulated during 297-398 sols along the MSL rover Curiosity traverse from Yellowknife Bay (YKB) up to Darwin outcrop area (DOA). Along the part of the rover traverse the DAN instrument conducted 140 local active mode measurements of the thermal and epithermal neutrons counts in the top ~60 cm of the Martian subsurface with horizontal sensing “footprint” of about 3 m. As it well seen based on Navcam and Mastcam images, the modern dominant micro-morphology of the rover traverse area is characteristic of surface shaped by strong aeolian deflation processes. It was found that the thermal and epithermal neutron counts measured along the rover traverse show distinct variability from one rover location to another. At that, a water equivalent of H (WEH) distribution in 60-cm subsurface layer along the rover traverse are fit by a two-layers model, where the top layer (with varied thickness) has less WEH (“dry”) than the bottom layer (“wet”). It is notably that two-layer model of the water distribution in the subsurface layer corresponds well to both outcrops spots and deflated surfaces with variable top layer thickness, that is composed of finely granulated and coarse, rocky soil. This suggests that the boundary between the top and bottom layer may not represent a lithological difference but rather it is related with a level of surface regolith desiccation at the modern climatic conditions in the Gale crater area. In places where the surface regolith has been exposed for a longer period of time, the contrast in WEH between the top and bottom layers is essentially lower than in the cases of more recent surface regolith exposure by an aeolian erosion.

  2. Morphology and oxygen incorporation effect on antimicrobial activity of silver thin films

    NASA Astrophysics Data System (ADS)

    Rebelo, Rita; Manninen, N. K.; Fialho, Luísa; Henriques, Mariana; Carvalho, Sandra

    2016-05-01

    Ag and AgxO thin films were deposited by non-reactive and reactive pulsed DC magnetron sputtering, respectively, with the final propose of functionalizing the SS316L substrate with antibacterial properties. The coatings were characterized chemically, physically and structurally. The coatings nanostructure was assessed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the coatings morphology was determined by scanning electron microscopy (SEM). The XRD and XPS analyses suggested that Ag thin film is composed by metallic Ag, which crystallizes in fcc-Ag phase, while the AgxO thin film showed both metallic Ag and Agsbnd O bonds, which crystalize in fcc-Ag and silver oxide phases. The SEM results revealed that Ag thin film formed a continuous layer, while AgxO layer was composed of islands with hundreds of nanometers surrounded by small nanoparticles with tens of nanometers. The surface wettability and surface tension parameters were determined by contact angle measurements, being found that Ag and AgxO surfaces showed very similar behavior, with all the surfaces showing a hydrophobic character. In order to verify the antibacterial behavior of the coatings, halo inhibition zone tests were realized for Staphylococcus epidermidis and Staphylococcus aureus. Ag coatings did not show antibacterial behavior, contrarily to AgxO coating, which presented antibacterial properties against the studied bacteria. The presence of silver oxide phase along with the development of different morphology was pointed as the main factors in the origin of the antibacterial effect found in AgxO thin film. The present study demonstrated that AgxO coating presented antibacterial behavior and its application in cardiovascular stents is promising.

  3. Platelet morphologic changes and fibrinogen receptor localization. Initial responses in ADP-activated human platelets.

    PubMed

    Hensler, M E; Frojmovic, M; Taylor, R G; Hantgan, R R; Lewis, J C

    1992-09-01

    Platelet exposure to agonists results in rapid morphologic changes paralleled by fibrinogen binding and platelet aggregation. The current study used standardized stereology in conjunction with immunogold electron microscopy to correlate the initial morphologic changes with fibrinogen receptor localization on the surfaces of ADP-activated human platelets. A 45% increase in platelet circumference was observed after 3 seconds of activation (P = 0.001). Virtually all of this increase was due to a 13-fold increase in projection membrane, and the projections observed by stereo microscopy at this time were mostly blunt. Both blunt and long projections also accounted for the increase in platelet-platelet contacts at 10 seconds of activation. Immunogold electron microscopy using the monoclonal antibodies P2 and AP-2 against the fibrinogen receptor, glycoprotein IIb/IIIa (GP IIb/IIIa), showed relatively equivalent immunogold densities on projections compared with cell body during 30 seconds of activation. The activation-dependent anti-GP IIb/IIIa monoclonal antibody, 7E3, showed an immunogold density 37% greater on projections compared with cell body (P = 0.0001). Colocalization studies using 7E3 with a polyclonal antifibrinogen antibody showed bound fibrinogen in close proximity to the GP IIb/IIIa localized by 7E3 on projections. These studies support an important role for platelet projections during the earliest stages of fibrinogen binding and ADP-induced aggregation.

  4. Application of Satellite SAR Imagery in Mapping the Active Layer of Arctic Permafrost

    NASA Technical Reports Server (NTRS)

    Zhang, Ting-Jun; Li, Shu-Sun

    2003-01-01

    The objective of this project is to map the spatial variation of the active layer over the arctic permafrost in terms of two parameters: (i) timing and duration of thaw period and (ii) differential frost heave and thaw settlement of the active layer. To achieve this goal, remote sensing, numerical modeling, and related field measurements are required. Tasks for the University of Colorado team are to: (i) determine the timing of snow disappearance in spring through changes in surface albedo (ii) simulate the freezing and thawing processes of the active layer and (iii) simulate the impact of snow cover on permafrost presence.

  5. Morphology, input-output relations and synaptic connectivity of Cajal-Retzius cells in layer 1 of the developing neocortex of CXCR4-EGFP mice.

    PubMed

    Anstötz, Max; Cosgrove, Kathleen E; Hack, Iris; Mugnaini, Enrico; Maccaferri, Gianmaria; Lübke, Joachim H R

    2014-11-01

    Layer 1 (L1) neurons, in particular Cajal-Retzius (CR) cells are among the earliest generated neurons in the neocortex. However, their role and that of L1 GABAergic interneurons in the establishment of an early cortical microcircuit are still poorly understood. Thus, the morphology of whole-cell recorded and biocytin-filled CR cells was investigated in postnatal day (P) 7-11 old CXCR4-EGFP mice where CR cells can be easily identified by their fluorescent appearance. Confocal-, light- and subsequent electron microscopy was performed to investigate their developmental regulation, morphology, synaptic input-output relationships and electrophysiological properties. CR cells reached their peak in occurrence between P4 to P7 and from thereon declined to almost complete disappearance at P14 by undergoing selective cell death through apoptosis. CR cells formed a dense and long-range horizontal network in layer 1 with a remarkable high density of synaptic boutons along their axons. They received dense GABAergic and non-GABAergic synaptic input and in turn provided synaptic output preferentially with spines or shafts of terminal tuft dendrites of pyramidal neurons. Interestingly, no dye-coupling between CR cells with other cortical neurons was observed as reported for other species, however, biocytin-labeling of individual CR cells leads to co-staining of L1 end foot astrocytes. Electrophysiologically, CR cells are characterized by a high input resistance and a characteristic firing pattern. Increasing depolarizing currents lead to action potential of decreasing amplitude and increasing half width, often terminated by a depolarization block. The presence of membrane excitability, the high density of CR cells in layer 1, their long-range horizontal axonal projection together with a high density of synaptic boutons and their synaptic input-output relationship suggest that they are an integral part of an early cortical network important not only in layer 1 but also for the

  6. Orexin-dependent activation of layer VIb enhances cortical network activity and integration of non-specific thalamocortical inputs.

    PubMed

    Hay, Y Audrey; Andjelic, Sofija; Badr, Sammy; Lambolez, Bertrand

    2015-11-01

    Neocortical layer VI is critically involved in thalamocortical activity changes during the sleep/wake cycle. It receives dense projections from thalamic nuclei sensitive to the wake-promoting neuropeptides orexins, and its deepest part, layer VIb, is the only cortical lamina reactive to orexins. This convergence of wake-promoting inputs prompted us to investigate how layer VIb can modulate cortical arousal, using patch-clamp recordings and optogenetics in rat brain slices. We found that the majority of layer VIb neurons were excited by nicotinic agonists and orexin through the activation of nicotinic receptors containing α4-α5-β2 subunits and OX2 receptor, respectively. Specific effects of orexin on layer VIb neurons were potentiated by low nicotine concentrations and we used this paradigm to explore their intracortical projections. Co-application of nicotine and orexin increased the frequency of excitatory post-synaptic currents in the ipsilateral cortex, with maximal effect in infragranular layers and minimal effect in layer IV, as well as in the contralateral cortex. The ability of layer VIb to relay thalamocortical inputs was tested using photostimulation of channelrhodopsin-expressing fibers from the orexin-sensitive rhomboid nucleus in the parietal cortex. Photostimulation induced robust excitatory currents in layer VIa neurons that were not pre-synaptically modulated by orexin, but exhibited a delayed, orexin-dependent, component. Activation of layer VIb by orexin enhanced the reliability and spike-timing precision of layer VIa responses to rhomboid inputs. These results indicate that layer VIb acts as an orexin-gated excitatory feedforward loop that potentiates thalamocortical arousal.

  7. Molecular mechanisms of activity-dependent changes in dendritic morphology: role of RGK proteins

    PubMed Central

    Ghiretti, Amy E.; Paradis, Suzanne

    2014-01-01

    The nervous system has the amazing capacity to transform sensory experience from the environment into changes in neuronal activity that, in turn, cause long-lasting alterations in neuronal morphology. Recent findings illustrate a somewhat surprising result: sensory experience concurrently activates molecular signaling pathways that both promote and inhibit dendritic complexity. Historically, a number of positive regulators of activity-dependent dendritic complexity have been described, while the list of identified negative regulators of this process is much shorter. In recent years, there has been an emerging appreciation of the importance of the Rad/Rem/Rem2/Gem/Kir (RGK) GTPases as mediators of activity-dependent structural plasticity. In the following review, we discuss the traditional view of RGK proteins, as well as our evolving understanding of the role of these proteins in instructing structural plasticity. PMID:24910262

  8. Active Tectonics in crossroads of an evolving orogen and morphological consequences: Anatolia

    NASA Astrophysics Data System (ADS)

    Koral, Hayrettin

    2016-04-01

    Anatolia lies in a curved setting of the active Alpine Mountain Range and is located in crossroads of the European and Asian terrains. It is one of the fastest deforming land in the world, manifested by seismicity, characteristic landforms and GPS measurements. Active tectonics in Anatolia provides not only a comparable geological model for the past orogens, but also a laboratory case for morphological consequences of an orogenic processes. Anatolia comprise different tectonic subsettings with its own characteristics. Northern part is influenced by tectonic characteristics of the Black Sea Basin, the Pontides and the Caucasian Range; northwestern part by the Balkanides; eastern-southeastern part by the Bitlis-Zagros suture; and south-southwestern part by the eastern Mediterranean subduction setting. Much of its present tectonic complexity was inherited from the convergence dominant plate tectonic setting of the platelets prior to the Middle-Neogene. Beginning about 11 Ma ago, the deformed and uplifted landmass unable to accommodate further deformation in Anatolia and ongoing tectonic activity gave rise to rearrangement of tectonic forces and westerly translational movements. Formation of major strike-slip faults in Anatolia including the North and East Anatolian Faults and a new platelet called the Anatolian Plate are the consequences of this episode. Such change in the tectonic regime has led to modification of previously-formed landscape, modification and sometimes termination of previously-formed basins. Evidence is present in the Plio-Quaternary stratigraphy, tectonic characteristics and morphology of the well-studied areas. This presentation will discuss active tectonic features of the northwestern, southwestern and eastern Anatolian subsettings and their influence on morphology that is closely related to sites of pre-historical human settlement.

  9. Morphological and metabolic changes in the cortex of mice lacking the functional presynaptic active zone protein bassoon: a combined 1H-NMR spectroscopy and histochemical study.

    PubMed

    Angenstein, Frank; Hilfert, Liane; Zuschratter, Werner; Altrock, Wilko D; Niessen, Heiko G; Gundelfinger, Eckart D

    2008-04-01

    Mice lacking functional presynaptic active zone protein Bassoon are characterized by an enlarged cerebral cortex and an altered cortical activation pattern. This morphological and functional phenotype is associated with defined metabolic distortions as detected by a metabonomic approach using high-field (14.1 T) high-resolution 1H-nuclear magnetic resonance spectroscopy (MRS) in conjunction with statistical pattern recognition. Within the cortex but not in the cerebellum, concentrations of N-acetyl aspartate, glutamine, and glutamate are significantly reduced, whereas the majority of all other detectable low molecular metabolites are unchanged. The reduction of the neuron-specific metabolite N-acetyl aspartate in the cortex coincides with a significant decrease in neuronal density in cortical layer V. Comparing the neuron with glia cell densities across the cortex reveals cortex layer-dependent alterations in the ratio between both cell types. Whereas the ratio shifts significantly toward neurons in the cortical input layers IV, the ratio is reversed in cortical layer V. Consequently, the previously observed altered neuronal activation pattern in the cortex is reflected not only in defined cytoarchitectural anomalies but also in metabolic disturbances in the glutamine-glutamate and N-acetyl aspartate metabolism.

  10. Creation of freestanding wrinkled nano-films with desired deformation properties by controlling the surface morphology of a sacrificial layer

    NASA Astrophysics Data System (ADS)

    Hirakata, Hiroyuki; Maruyama, Tomohiro; Yonezu, Akio; Minoshima, Kohji

    2013-05-01

    Various wrinkle patterns can be formed due to the buckling of a stiff thin film on a compliant substrate. However, most wrinkled films previously reported were fixed on a large deformable substrate and thereby the potential deformability of the film was mechanically constrained by the substrate. In this study, we developed a technique for forming various wrinkled structures on the surface of a sacrificial resin layer. Since the sacrificial layer can be subsequently removed with a solvent, freestanding wrinkled films are created using the sacrificial layer. We found that a wrinkled structure is formed on the surface of the layer by applying a compressive strain to the resin layer at the appropriate moment during the hardening process. The wrinkle pattern depends on the curing time and the timing of the straining in two in-plane orthogonal directions. In addition to conventional stripe and labyrinth patterns by simple uniaxial and equi-biaxial strains, respectively, it was found that independent biaxial strains induce interesting structures, such as an orthogonally ordered wrinkle pattern and a nonsymmetrical buckling structure, in which the stripe array produced by the first straining remains and many finer wrinkles appear in each stripe by the second straining in the orthogonal direction. We conducted tensile experiments for 300-nm-thick freestanding Cu films having these wrinkled structures. The wrinkled nano-films have a variety of mechanical properties: the stripe structure has extremely high deformability (more than 10% strain) and reversibility, the labyrinth structure shows planar isotropic deformation, and the nonsymmetrical buckling structure has an anisotropic modulus and strength. Finite element analysis on the wrinkle structures revealed that the local stress concentration dominates the fracture limits.

  11. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. II - NOAA active region 5747 (1989 October)

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Canfield, Richard C.; Mcclymont, A. N.; De La Beaujardiere, J.-F.; Fan, Yuhong; Tang, F.

    1993-01-01

    The paper describes October 1989 observations in NOAA Active Region 5747 of the morphology of energetic electron precipitation and high-pressure coronal flare plasmas of three flares and their relation to the vector magnetic field and vertical electric currents. The H-alpha spectroheliograms were coaligned with the vector magnetograms using continuum images of sunspots, enabling positional accuracy of a few arcsec. It was found that, during the gradual phase, the regions of the H-alpha flare that show the effects of enhanced pressure in the overlying corona often encompass extrema of the vertical current density, consistent with earlier work showing a close relationship between H-alpha emission and line-of-sight currents. The data are also consistent with the overall morphology and evolution described by erupting-filament models such as those of Kopp and Pneuman (1976) and Sturrock (1989).

  12. The Role of Organic Capping Layers of Platinum Nanoparticles in Catalytic Activity of CO Oxidation

    SciTech Connect

    Park, Jeong Y.; Aliaga, Cesar; Renzas, J. Russell; Lee, Hyunjoo; Somorjai, Gabor A.

    2008-12-17

    We report the catalytic activity of colloid platinum nanoparticles synthesized with different organic capping layers. On the molecular scale, the porous organic layers have open spaces that permit the reactant and product molecules to reach the metal surface. We carried out CO oxidation on several platinum nanoparticle systems capped with various organic molecules to investigate the role of the capping agent on catalytic activity. Platinum colloid nanoparticles with four types of capping layer have been used: TTAB (Tetradecyltrimethylammonium Bromide), HDA (hexadecylamine), HDT (hexadecylthiol), and PVP (poly(vinylpyrrolidone)). The reactivity of the Pt nanoparticles varied by 30%, with higher activity on TTAB coated nanoparticles and lower activity on HDT, while the activation energy remained between 27-28 kcal/mol. In separate experiments, the organic capping layers were partially removed using ultraviolet light-ozone generation techniques, which resulted in increased catalytic activity due to the removal of some of the organic layers. These results indicate that the nature of chemical bonding between organic capping layers and nanoparticle surfaces plays a role in determining the catalytic activity of platinum colloid nanoparticles for carbon monoxide oxidation.

  13. Cobalt on rhenium(0001) an example of thermally activated layer intermixing and surface alloying

    NASA Astrophysics Data System (ADS)

    Parschau, M.; Christmann, K.

    1999-03-01

    The growth and morphology of cobalt thin films deposited onto a Re(0001) surface at 300, 400 and 550 K were followed in the coverage range 0 ML< Θ<6 ML by combined low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The interaction phenomena are complex and depend strongly on temperature. At 300 K, cobalt nucleates homogeneously on terraces and heterogeneously at steps forming dendritic islands. Larger cobalt coverages lead to incomplete layer growth. Interdiffusion and alloying play a minor role only at 300 K, but become dominant for T>400 K in that different (2×2) phases form within the first Re-Co bilayer, one within the rhenium substrate surface, the others within the cobalt islands. The (2×2) phases can be associated with Re/Co surface alloys of different stoichiometry, depending on cobalt coverage. As the cobalt coverages exceed two monolayers (ML), genuine but incomplete cobalt layers grow. Within the third and fourth cobalt layer, periodic triangular features with a lattice constant of ~28 Å appear in STM, followed by a Moiré pattern for Θ>4 ML. Both structures produce an incomplete (10×10) LEED pattern. After growth of the fifth or sixth layer the lattice misfit is overcome, and cobalt essentially grows layer-by-layer in a pseudo Frank-van der Merwe mechanism, the details being strongly temperature-dependent.

  14. Application of Satellite SAR Imagery in Mapping the Active Layer of Arctic Permafrost

    NASA Technical Reports Server (NTRS)

    Li, Shu-Sun; Romanovsky, V.; Lovick, Joe; Wang, Z.; Peterson, Rorik

    2003-01-01

    A method of mapping the active layer of Arctic permafrost using a combination of conventional synthetic aperture radar (SAR) backscatter and more sophisticated interferometric SAR (INSAR) techniques is proposed. The proposed research is based on the sensitivity of radar backscatter to the freeze and thaw status of the surface soil, and the sensitivity of INSAR techniques to centimeter- to sub-centimeter-level surface differential deformation. The former capability of SAR is investigated for deriving the timing and duration of the thaw period for surface soil of the active layer over permafrost. The latter is investigated for the feasibility of quantitative measurement of frost heaving and thaw settlement of the active layer during the freezing and thawing processes. The resulting knowledge contributes to remote sensing mapping of the active layer dynamics and Arctic land surface hydrology.

  15. Influence of wastewater treatment plants' operational conditions on activated sludge microbiological and morphological characteristics.

    PubMed

    Amanatidou, Elisavet; Samiotis, Georgios; Trikoilidou, Eleni; Tzelios, Dimitrios; Michailidis, Avraam

    2016-01-01

    The effect of wastewater composition and operating conditions in activated sludge (AS) microbiological and morphological characteristics was studied in three AS wastewater treatment plants (WWTPs): (a) a high organic load slaughterhouse AS WWTP, operating at complete solids retention, monitored from its start-up and for 425 days; (b) a seasonally operational, low nitrogen load fruit canning industry AS WWTP, operating at complete solids retention, monitored from its start-up and until the end of the season (87 days); (c) a municipal AS WWTP, treating wastewater from a semi-combined sewer system, monitored during the transitions from dry to rainy and again to dry periods of operation. The sludge microbiological and morphological characteristics were correlated to nutrients' availability, solids retention time, hydraulic retention time, dissolved oxygen, mixed liquor suspended solids (MLVSS), organic load (F/M) and substrate utilization rate. The AS WWTPs' operation was distinguished in periods based on biomass growth phase, characterized by different biological and morphological characteristics and on operational conditions. An anoxic/aerobic selector minimizes the readily biodegradable compounds in influent, inhibiting filamentous growth. Plant performance controlling is presented in a logic flowchart in which operational parameters are linked to microbial manipulation, resulting in a useful tool for researchers and engineers. PMID:26145184

  16. Effect of substrate (ZnO) morphology on enzyme immobilization and its catalytic activity

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Wu, Haixia; Huang, Xuelei; Zhang, Jingyan; Guo, Shouwu

    2011-07-01

    In this study, zinc oxide (ZnO) nanocrystals with different morphologies were synthesized and used as substrates for enzyme immobilization. The effects of morphology of ZnO nanocrystals on enzyme immobilization and their catalytic activities were investigated. The ZnO nanocrystals were prepared through a hydrothermal procedure using tetramethylammonium hydroxide as a mineralizing agent. The control on the morphology of ZnO nanocrystals was achieved by varying the ratio of CH3OH to H2O, which were used as solvents in the hydrothermal reaction system. The surface of as-prepared ZnO nanoparticles was functionalized with amino groups using 3-aminopropyltriethoxysilane and tetraethyl orthosilicate, and the amino groups on the surface were identified and calculated by FT-IR and the Kaiser assay. Horseradish peroxidase was immobilized on as-modified ZnO nanostructures with glutaraldehyde as a crosslinker. The results showed that three-dimensional nanomultipod is more appropriate for the immobilization of enzyme used further in catalytic reaction.

  17. Influence of wastewater treatment plants' operational conditions on activated sludge microbiological and morphological characteristics.

    PubMed

    Amanatidou, Elisavet; Samiotis, Georgios; Trikoilidou, Eleni; Tzelios, Dimitrios; Michailidis, Avraam

    2016-01-01

    The effect of wastewater composition and operating conditions in activated sludge (AS) microbiological and morphological characteristics was studied in three AS wastewater treatment plants (WWTPs): (a) a high organic load slaughterhouse AS WWTP, operating at complete solids retention, monitored from its start-up and for 425 days; (b) a seasonally operational, low nitrogen load fruit canning industry AS WWTP, operating at complete solids retention, monitored from its start-up and until the end of the season (87 days); (c) a municipal AS WWTP, treating wastewater from a semi-combined sewer system, monitored during the transitions from dry to rainy and again to dry periods of operation. The sludge microbiological and morphological characteristics were correlated to nutrients' availability, solids retention time, hydraulic retention time, dissolved oxygen, mixed liquor suspended solids (MLVSS), organic load (F/M) and substrate utilization rate. The AS WWTPs' operation was distinguished in periods based on biomass growth phase, characterized by different biological and morphological characteristics and on operational conditions. An anoxic/aerobic selector minimizes the readily biodegradable compounds in influent, inhibiting filamentous growth. Plant performance controlling is presented in a logic flowchart in which operational parameters are linked to microbial manipulation, resulting in a useful tool for researchers and engineers.

  18. Dynamics of the Thermal State of Active Layer at the Alaska North Slope and Northern Yakutia

    NASA Astrophysics Data System (ADS)

    Kholodov, A. L.; Romanovsky, V. E.; Marchenko, S.; Shiklomanov, N. I.; Fedorov-Davydov, D.

    2010-12-01

    Dynamics of the active layer is one of the most important indexes, reflecting permafrost response to the modern climate changes. Monitoring of active layer thickness dynamics is the main goal of CALM (Circumpolar Active Layer Monitoring) project. But, from different points of view, it is very important to know not only maximal depth of seasonal thawing but also dynamics of thermal field of active layer and duration of its staying in the unfrozen state. Current research was aimed on the analyzing data of temperature measurements have been done during the more then 10 years at the North Slope of Brooks Range (Alaska) and 2 years at the selected sites at the Northern Yakutia (Russia) and its comparison with the 17 to 10 years records of active layer thickness dynamics at the corresponding sites (http://www.udel.edu/Geography/calm/data/north.html). The area of investigation characterized by the typical tundra landscape and different kinds of micro topography. Reported observation sites located at the latitudinal range from 68.5 to 70.3N in Alaska and 70.5 to 71.75N in the Northern Yakutia. Observation have been done using the 1 meter long MRC probe with 11 sensors (every 10 cm) and single Campbell SCI A107 sensors in Alaska and 2-channel HOBO U23 data loggers with TMC-HD thermistors in the Northern Yakutia. Analyses of CALM data show what most observation sites in Alaska (except located near the Brooks Range and at the Arctic Ocean coast) do not subjected to the significant sustainable changes of active layer thickness over the last 10 years. At the same time active layer thickness at the Yakutian sites was increasing. Temperature observations show decreasing of the mean annual temperature at the average depth of active layer bottom at the Alaskan sites. But, because of general trend to increasing of period of thawing it does not lead to the decreasing of active layer thickness. Recent equipment deployment at the Tiksi and Allaikha sites (Northern Yakutia) does not

  19. Linking morphology with activity through the lifetime of pretreated PtNi nanostructured thin film catalysts

    DOE PAGES

    Cullen, David A.; Lopez-Haro, Miguel; Bayle-Guillemaud, Pascale; Debe, Mark; Steinbach, Andrew J.; Guetaz, L.

    2015-04-10

    In this study, the nanoscale morphology of highly active Pt3Ni7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by high resolution imaging, elemental mapping and tomography. The dissolution of Ni during fuel cell conditioning leads to highly complex, porous structures which were visualized in 3D by electron tomography. Quantification of the rendered surfaces following catalyst pretreatment, conditioning, and cycling shows the important role pore structure plays in surfacemore » area, activity, and durability.« less

  20. Linking morphology with activity through the lifetime of pretreated PtNi nanostructured thin film catalysts

    SciTech Connect

    Cullen, David A.; Lopez-Haro, Miguel; Bayle-Guillemaud, Pascale; Debe, Mark; Steinbach, Andrew J.; Guetaz, L.

    2015-04-10

    In this study, the nanoscale morphology of highly active Pt3Ni7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by high resolution imaging, elemental mapping and tomography. The dissolution of Ni during fuel cell conditioning leads to highly complex, porous structures which were visualized in 3D by electron tomography. Quantification of the rendered surfaces following catalyst pretreatment, conditioning, and cycling shows the important role pore structure plays in surface area, activity, and durability.

  1. Impact of streambed morphology on the abundance and activity of ammonia-oxidizing bacteria.

    PubMed

    Yanuka-Golub, Keren; Arnon, Shai; Nejidat, Ali

    2014-10-01

    Ammonia oxidizers catalyze the first step of nitrification. Combined microbial nitrification-denitrification activities are essential for the removal of excess nitrogen from water bodies. In sandy streambeds, bed form structures are created by water flow and lead to the creation of heterogeneous microenvironments. The objective of this study, therefore, was to investigate the effect of bed form morphology on the abundance and activity of ammonia-oxidizing bacteria (AOB) within a benthic biofilm. An 8-month-old benthic biofilm was established in a recirculating laboratory flume under controlled flow conditions and frequent amendment with ammonium. The sand bed was arranged into bed form structures. The highest concentrations of chlorophyll a (indicative of algae) were measured on the upstream side of the bed forms. The biofilm was dominated by Nitrosospira species, and amoA gene abundance was higher on the downstream sides of the bed forms with no significant difference in oxygen consumption between the upstream and downstream sections of the bed form. In contrast, potential ammonium oxidation rates were higher on the upstream sides of the bed forms. The results suggest that bed form morphology can affect the spatial distribution and activity of AOB, possibly through the creation of distinct microhabitats. These results contribute to our understanding of nitrogen transformations and removal from streams. PMID:25056670

  2. Improving ice nucleation activity of zein film through layer-by-layer deposition of extracellular ice nucleators.

    PubMed

    Shi, Ke; Yu, Hailong; Lee, Tung-Ching; Huang, Qingrong

    2013-11-13

    Zein protein has been of scientific interest in the development of biodegradable functional food packaging. This study aimed at developing a novel zein-based biopolymer film with ice nucleation activity through layer-by-layer deposition of biogenic ice nucleators, that is, extracellular ice nucleators (ECINs) isolated from Erwinia herbicola , onto zein film surface. The adsorption behaviors and mechanisms were investigated using quartz crystal microbalance with dissipation monitoring (QCM-D). On unmodified zein surface, the highest ECINs adsorption occurred at pH 5.0; on UV/ozone treated zein surface followed by deposition of poly(diallyldimethylammonium chloride) (PDADMAC) layer, the optimum condition for ECINs adsorption occurred at pH 7.0 and I 0.05 M, where the amount of ECINs adsorbed was also higher than that on unmodified zein surface. QCM-D analyses further revealed a two-step adsorption process on unmodified zein surfaces, compared to a one-step adsorption process on PDADMAC-modified zein surface. Also, significantly, in order to quantify the ice nucleation activity of ECINs-coated zein films, an empirical method was developed to correlate the number of ice nucleators with the ice nucleation temperature measured by differential scanning calorimetry. Calculated using this empirical method, the highest ice nucleation activity of ECINs on ECINs-modified zein film reached 64.1 units/mm(2), which was able to elevate the ice nucleation temperature of distilled water from -15.5 °C to -7.3 °C.

  3. Analysis of LiDAR-derived topographic information for characterizing and differentiating landslide morphology and activity

    NASA Astrophysics Data System (ADS)

    Glenn, Nancy F.; Streutker, David R.; Chadwick, D. John; Thackray, Glenn D.; Dorsch, Stephen J.

    2006-01-01

    This study used airborne laser altimetry (LiDAR) to examine the surface morphology of two canyon-rim landslides in southern Idaho. The high resolution topographic data were used to calculate surface roughness, slope, semivariance, and fractal dimension. These data were combined with historical movement data (Global Positioning Systems (GPS) and laser theodolite) and field observations for the currently active landslide, and the results suggest that topographic elements are related to the material types and the type of local motion of the landslide. Weak, unconsolidated materials comprising the toe of the slide, which were heavily fractured and locally thrust upward, had relatively high surface roughness, high fractal dimension, and high vertical and lateral movement. The body of the slide, which predominantly moved laterally and consists mainly of undisturbed, older canyon floor materials, had relatively lower surface roughness than the toe. The upper block, consisting of a down-dropped section of the canyon rim that has remained largely intact, had a low surface roughness on its upper surface and high surface roughness along fractures and on its west face (unrelated to landslide motion). The upper block also had a higher semivariance than the toe and body. The topographic data for a neighboring, older and larger landslide complex, which failed in 1937, are similarly used to understand surface morphology, as well as to compare to the morphology of the active landslide and to understand scale-dependent processes. The morphometric analyses demonstrate that the active landslide has a similar failure mechanism and is topographically more variable than the 1937 landslide, especially at scales > 20 m. Weathering and the larger scale processes of the 1937 slide are hypothesized to cause the lower semivariance values of the 1937 slide. At smaller scales (< 10 m) the topographic components of the two landslides have similar roughness and semivariance. Results demonstrate

  4. Evolution of surface morphology and electronic structure of few layer graphene after low energy Ar{sup +} ion irradiation

    SciTech Connect

    Al-Harthi, S. H.; Kara'a, A.; Elzain, M.; Hysen, T.; Al-Hinai, A. T.; Myint, M. T. Z.

    2012-11-19

    We report on co-existing dual anisotropy ripple formation, sp bonding transformation, and variation in the delocalized {pi} electron system in 1 keV Ar{sup +} ion irradiated few-layer graphene surfaces. Ripples in directions, perpendicular and parallel to the ion beam were found. The irradiation effect and the transition from the sp{sup 2}-bonding to sp{sup 3}-hybridized state were analyzed from the deconvolution of the C (1s) peak and from the shape of the derivative of the Auger transition spectra. The results suggest a plausible mechanism for tailoring of few-layer graphene electronic band structure with interlayer coupling tuned by the ion irradiation.

  5. Depth heterogeneity of fully aromatic polyamide active layers in reverse osmosis and nanofiltration membranes.

    PubMed

    Coronell, Orlando; Mariñas, Benito J; Cahill, David G

    2011-05-15

    We studied the depth heterogeneity of fully aromatic polyamide (PA) active layers in commercial reverse osmosis (RO) and nanofiltration (NF) membranes by quantifying near-surface (i.e., top 6 nm) and volume-averaged properties of the active layers using X-ray photoelectron spectrometry (XPS) and Rutherford backscattering spectrometry (RBS), respectively. Some membranes (e.g., ESPA3 RO) had active layers that were depth homogeneous with respect to the concentration and pK(a) distribution of carboxylic groups, degree of polymer cross-linking, concentration of barium ion probe that associated with ionized carboxylic groups, and steric effects experienced by barium ion. Other membranes (e.g., NF90 NF) had active layers that were depth heterogeneous with respect to the same properties. Our results therefore support the existence of both depth-homogeneous and depth-heterogeneous active layers. It remains to be assessed whether the depth heterogeneity consists of gradually changing properties throughout the active layer depth or of distinct sublayers with different properties.

  6. Activity of lactoperoxidase when adsorbed on protein layers.

    PubMed

    Haberska, Karolina; Svensson, Olof; Shleev, Sergey; Lindh, Liselott; Arnebrant, Thomas; Ruzgas, Tautgirdas

    2008-09-15

    Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9mg/m(2). A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.

  7. Electrical and morphological properties of conducting layers formed from the silver-glass composite conducting powders prepared by spray pyrolysis.

    PubMed

    Jung, D S; Koo, H Y; Kang, Y C

    2010-03-01

    Ag-glass composite powders with various glass contents and excellent conducting properties were prepared by spray pyrolysis. Irrespective of the glass content, all the prepared powders were found to comprise spherical particles with nonaggregation characteristics. The crystal structure of the powder particles resembled that of pure Ag particles, irrespective of the glass content. Conducting layers formed from pure Ag did not melt even when sintered at 400 degrees C. On the other hand, conducting layers formed from composite powders containing 3 and 5 wt% glass melted when sintered at 400 degrees C. The optimum glass content of the composite powders was 3 wt% at sintering temperatures of 400 and 450 degrees C. However, the optimum glass content decreased to 1 wt% when the sintering temperature was increased to 550 degrees C. The lowest specific resistances of the conducting layers formed from the composite powders were 5.3 and 2.3 microohms-cm at sintering temperatures of 400 and 550 degrees C, respectively. PMID:20036371

  8. Overexpression of Guanylate Cyclase Activating Protein 2 in Rod Photoreceptors In Vivo Leads to Morphological Changes at the Synaptic Ribbon

    PubMed Central

    López-Begines, Santiago; Fernández-Sánchez, Laura; Cuenca, Nicolás; Llorens, Jordi; de la Villa, Pedro; Méndez, Ana

    2012-01-01

    Guanylate cyclase activating proteins are EF-hand containing proteins that confer calcium sensitivity to retinal guanylate cyclase at the outer segment discs of photoreceptor cells. By making the rate of cGMP synthesis dependent on the free intracellular calcium levels set by illumination, GCAPs play a fundamental role in the recovery of the light response and light adaptation. The main isoforms GCAP1 and GCAP2 also localize to the synaptic terminal, where their function is not known. Based on the reported interaction of GCAP2 with Ribeye, the major component of synaptic ribbons, it was proposed that GCAP2 could mediate the synaptic ribbon dynamic changes that happen in response to light. We here present a thorough ultrastructural analysis of rod synaptic terminals in loss-of-function (GCAP1/GCAP2 double knockout) and gain-of-function (transgenic overexpression) mouse models of GCAP2. Rod synaptic ribbons in GCAPs−/− mice did not differ from wildtype ribbons when mice were raised in constant darkness, indicating that GCAPs are not required for ribbon early assembly or maturation. Transgenic overexpression of GCAP2 in rods led to a shortening of synaptic ribbons, and to a higher than normal percentage of club-shaped and spherical ribbon morphologies. Restoration of GCAP2 expression in the GCAPs−/− background (GCAP2 expression in the absence of endogenous GCAP1) had the striking result of shortening ribbon length to a much higher degree than overexpression of GCAP2 in the wildtype background, as well as reducing the thickness of the outer plexiform layer without affecting the number of rod photoreceptor cells. These results indicate that preservation of the GCAP1 to GCAP2 relative levels is relevant for maintaining the integrity of the synaptic terminal. Our demonstration of GCAP2 immunolocalization at synaptic ribbons at the ultrastructural level would support a role of GCAPs at mediating the effect of light on morphological remodeling changes of synaptic

  9. Crystallinity Modulation of Layered Carbon Nitride for Enhanced Photocatalytic Activities.

    PubMed

    Wang, Jianhai; Shen, Yanfei; Li, Ying; Liu, Songqin; Zhang, Yuanjian

    2016-08-22

    As an emerging metal-free semiconductor, covalently bonded carbon nitride (CN) has attracted much attention in photocatalysis. However, drawbacks such as a high recombination rate of excited electrons and holes hinder its potential applications. Tailoring the crystallinity of semiconductors is an important way to suppress unwanted charge recombination, but has rarely been applied to CN so far. Herein, a simple method to synthesize CN of high crystallinity by protonation of specific intermediate species during conventional polymerization is reported. Interestingly, the as-obtained CN exhibited improved photocatalytic activities of up to seven times those of the conventional bulk CN. This approach, with only a slight change to the conventional method, provides a facile way to effectively regulate the crystallinity of bulk CN to improve its photocatalytic activities and sheds light on large-scale industrial applications of CN with high efficiency for sustainable energy. PMID:27436164

  10. Crystallinity Modulation of Layered Carbon Nitride for Enhanced Photocatalytic Activities.

    PubMed

    Wang, Jianhai; Shen, Yanfei; Li, Ying; Liu, Songqin; Zhang, Yuanjian

    2016-08-22

    As an emerging metal-free semiconductor, covalently bonded carbon nitride (CN) has attracted much attention in photocatalysis. However, drawbacks such as a high recombination rate of excited electrons and holes hinder its potential applications. Tailoring the crystallinity of semiconductors is an important way to suppress unwanted charge recombination, but has rarely been applied to CN so far. Herein, a simple method to synthesize CN of high crystallinity by protonation of specific intermediate species during conventional polymerization is reported. Interestingly, the as-obtained CN exhibited improved photocatalytic activities of up to seven times those of the conventional bulk CN. This approach, with only a slight change to the conventional method, provides a facile way to effectively regulate the crystallinity of bulk CN to improve its photocatalytic activities and sheds light on large-scale industrial applications of CN with high efficiency for sustainable energy.

  11. Soot Aerosol Particles as Cloud Condensation Nuclei: from Ice Nucleation Activity to Ice Crystal Morphology

    NASA Astrophysics Data System (ADS)

    Pirim, Claire; Ikhenazene, Raouf; Ortega, Isamel Kenneth; Carpentier, Yvain; Focsa, Cristian; Chazallon, Bertrand; Ouf, François-Xavier

    2016-04-01

    Emissions of solid-state particles (soot) from engine exhausts due to incomplete fuel combustion is considered to influence ice and liquid water cloud droplet activation [1]. The activity of these aerosols would originate from their ability to be important centers of ice-particle nucleation, as they would promote ice formation above water homogeneous freezing point. Soot particles are reported to be generally worse ice nuclei than mineral dust because they activate nucleation at higher ice-supersaturations for deposition nucleation and at lower temperatures for immersion freezing than ratios usually expected for homogeneous nucleation [2]. In fact, there are still numerous opened questions as to whether and how soot's physico-chemical properties (structure, morphology and chemical composition) can influence their nucleation ability. Therefore, systematic investigations of soot aerosol nucleation activity via one specific nucleation mode, here deposition nucleation, combined with thorough structural and compositional analyzes are needed in order to establish any association between the particles' activity and their physico-chemical properties. In addition, since the morphology of the ice crystals can influence their radiative properties [3], we investigated their morphology as they grow over both soot and pristine substrates at different temperatures and humidity ratios. In the present work, Combustion Aerosol STandart soot samples were produced from propane using various experimental conditions. Their nucleation activity was studied in deposition mode (from water vapor), and monitored using a temperature-controlled reactor in which the sample's relative humidity is precisely measured with a cryo-hygrometer. Formation of water/ice onto the particles is followed both optically and spectroscopically, using a microscope coupled to a Raman spectrometer. Vibrational signatures of hydroxyls (O-H) emerge when the particle becomes hydrated and are used to characterize ice

  12. Salix polaris growth responses to active layer detachment and solifluction processes in High Arctic.

    NASA Astrophysics Data System (ADS)

    Siekacz, Liliana

    2015-04-01

    The work is dedicated to demonstrate the potential of Salix polaris grow properties in the dendrogemorphologic image, analyzing periglacially induced slope processes in the high Arctic.. Observed anatomical and morphological plants responses to solifluction and active layer detachment processes are presented qualitatively and quantitatively as a summary of presented features frequency. The results are discussed against the background of the other research results in this field. The investigations was performed in Ebba valley, in the vicinity of Petunia Bay, northernmost part of Billefjorden in central Spitsbergen (Svalbard). Environmental conditions are characterized by annual precipitation sum lower than 200 mm (Hagen et al.,1993) and average summer temperature of about 5°C, with maximum daily temperatures rarely exceeding 10°C (Rachlewicz, 2009). Collected shrub material was prepared according to the methods presented by Schweingruber and Poschlod (2005). Thin (approx. 15-20μm) sections of the whole cross-section were prepared with a sledge microtome, stained with Safranine and Astra blue and finally permanently fixed on microslides with Canada balsam and dried. Snapshots were taken partially for each cross-section with digital camera (ColorView III, Olympus) connected to a microscope (Olympus BX41) and merged into one, high resolution image. After all, ring widths were measured in 3-4 radii in every single cross-section using ImageJ software. Analyzed plants revealed extremely harsh environmental conditions of their growth. Buchwał et al. (2013) provided quantitative data concerning missing rings and partially missing rings in shrubs growing on Ebba valley floor. Mean ring width at the level of 79μm represents one of the smallest values of yearly growth ever noted. The share of missing rings and partially missing rings was 11,2% and 13,6% respectively. Plants growing on Ebba valley slope indicate almost twice smaller values of ring width (41μm), and higher

  13. Contribution of S-Layer Proteins to the Mosquitocidal Activity of Lysinibacillus sphaericus

    PubMed Central

    Allievi, Mariana Claudia; Palomino, María Mercedes; Prado Acosta, Mariano; Lanati, Leonardo; Ruzal, Sandra Mónica; Sánchez-Rivas, Carmen

    2014-01-01

    Lysinibacillus sphaericus strains belonging the antigenic group H5a5b produce spores with larvicidal activity against larvae of Culex mosquitoes. C7, a new isolated strain, which presents similar biochemical characteristics and Bin toxins in their spores as the reference strain 2362, was, however, more active against larvae of Culex mosquitoes. The contribution of the surface layer protein (S-layer) to this behaviour was envisaged since this envelope protein has been implicated in the pathogenicity of several bacilli, and we had previously reported its association to spores. Microscopic observation by immunofluorescence detection with anti S-layer antibody in the spores confirms their attachment. S-layers and BinA and BinB toxins formed high molecular weight multimers in spores as shown by SDS-PAGE and western blot detection. Purified S-layer from both L. sphaericus C7 and 2362 strain cultures was by itself toxic against Culex sp larvae, however, that from C7 strain was also toxic against Aedes aegypti. Synergistic effect between purified S-layer and spore-crystal preparations was observed against Culex sp. and Aedes aegypti larvae. This effect was more evident with the C7 strain. In silico analyses of the S-layer sequence suggest the presence of chitin-binding and hemolytic domains. Both biochemical characteristics were detected for both S-layers strains that must justify their contribution to pathogenicity. PMID:25354162

  14. The Effect of Detergents on the Morphology and Immunomodulatory Activity of Malassezia furfur

    PubMed Central

    Kim, Su-Han; Ko, Hyun-Chang; Kwon, Kyung-Sool; Oh, Chang-Keun

    2009-01-01

    Background Several workers have found that Malassezia are capable of suppressing cytokine release and downregulating the phagocytic function of monocytes. But lipid-depleted Malassezia furfur (M. furfur) extracts have also been shown to induce increased production of TNF-α, IL-6 and IL-1β in monocytes. We thought that the detergents in shampoos or soaps could change the composition of the lipid in the M. furfur cell wall. Objective We studied whether detergents affect the morphology of M. furfur and if the inflammatory cytokine profiles change in the monocytes treated with detergent-treated M. furfur. Methods Commonly used detergents such as sodium lauryl sulfate, ammonium lauryl sulfate and tween-80 were respectively added to the modified Leeming-Notman's media. M. furfur was cultivated in each media (detergent-added or untreated). Thereafter, the surface morphology of the yeast was evaluated by scanning and transmission electron microscopy. The cytokine profiles of monocytes, which were treated by M. furfur with or without detergents, were also evaluated. Results The detergent-treated M. furfur were similar to the lipid-extracted form of M. furfur on the electron microscopic study, with a recessed, withered surface and with thinner and rather electron transparent cell walls than the detergent-untreated M. furfur. The levels of TNF-α were higher in monocytes treated with detergent-treated Malassezia than that in the monocytes treated with the detergent-untreated Malassezia (p<0.05). Conclusion According to the findings in this study, it could be inferred that the detergents in shampoos or soaps affect the lipid layers of the Malassezia cell wall and these lipid-extracted Malassezia induce or aggravate some inflammatory conditions. But to correlate the relationship between detergents and Malassezia-associated diseases, in vivo experiments that will focus on short-term contact with detergents in real life conditions should be done. PMID:20523770

  15. Dynamic myosin activation promotes collective morphology and migration by locally balancing oppositional forces from surrounding tissue

    PubMed Central

    Aranjuez, George; Burtscher, Ashley; Sawant, Ketki; Majumder, Pralay; McDonald, Jocelyn A.

    2016-01-01

    Migrating cells need to overcome physical constraints from the local microenvironment to navigate their way through tissues. Cells that move collectively have the additional challenge of negotiating complex environments in vivo while maintaining cohesion of the group as a whole. The mechanisms by which collectives maintain a migratory morphology while resisting physical constraints from the surrounding tissue are poorly understood. Drosophila border cells represent a genetic model of collective migration within a cell-dense tissue. Border cells move as a cohesive group of 6−10 cells, traversing a network of large germ line–derived nurse cells within the ovary. Here we show that the border cell cluster is compact and round throughout their entire migration, a shape that is maintained despite the mechanical pressure imposed by the surrounding nurse cells. Nonmuscle myosin II (Myo-II) activity at the cluster periphery becomes elevated in response to increased constriction by nurse cells. Furthermore, the distinctive border cell collective morphology requires highly dynamic and localized enrichment of Myo-II. Thus, activated Myo-II promotes cortical tension at the outer edge of the migrating border cell cluster to resist compressive forces from nurse cells. We propose that dynamic actomyosin tension at the periphery of collectives facilitates their movement through restrictive tissues. PMID:27122602

  16. Estimating 3D variation in active-layer thickness beneath arctic streams using ground-penetrating radar

    USGS Publications Warehouse

    Brosten, T.R.; Bradford, J.H.; McNamara, J.P.; Gooseff, M.N.; Zarnetske, J.P.; Bowden, W.B.; Johnston, M.E.

    2009-01-01

    We acquired three-dimensional (3D) ground-penetrating radar (GPR) data across three stream sites on the North Slope, AK, in August 2005, to investigate the dependence of thaw depth on channel morphology. Data were migrated with mean velocities derived from multi-offset GPR profiles collected across a stream section within each of the 3D survey areas. GPR data interpretations from the alluvial-lined stream site illustrate greater thaw depths beneath riffle and gravel bar features relative to neighboring pool features. The peat-lined stream sites indicate the opposite; greater thaw depths beneath pools and shallower thaw beneath the connecting runs. Results provide detailed 3D geometry of active-layer thaw depths that can support hydrological studies seeking to quantify transport and biogeochemical processes that occur within the hyporheic zone.

  17. Citral exerts its antifungal activity against Penicillium digitatum by affecting the mitochondrial morphology and function.

    PubMed

    Zheng, Shiju; Jing, Guoxing; Wang, Xiao; Ouyang, Qiuli; Jia, Lei; Tao, Nengguo

    2015-07-01

    This work investigated the effect of citral on the mitochondrial morphology and function of Penicillium digitatum. Citral at concentrations of 2.0 or 4.0 μL/mL strongly damaged mitochondria of test pathogen by causing the loss of matrix and increase of irregular mitochondria. The deformation extent of the mitochondria of P. digitatum enhanced with increasing concentrations of citral, as evidenced by a decrease in intracellular ATP content and an increase in extracellular ATP content of P. digitatum cells. Oxygen consumption showed that citral resulted in an inhibition in the tricarboxylic acid cycle (TCA) pathway of P. digitatum cells, induced a decrease in activities of citrate synthetase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinodehydrogenase and the content of citric acid, while enhancing the activity of malic dehydrogenase in P. digitatum cells. Our present results indicated that citral could damage the mitochondrial membrane permeability and disrupt the TCA pathway of P. digitatum.

  18. Active shoreline of Ontario Lacus, Titan: A morphological study of the lake and its surroundings

    USGS Publications Warehouse

    Wall, S.; Hayes, A.; Bristow, C.; Lorenz, R.; Stofan, E.; Lunine, J.; Le, Gall A.; Janssen, M.; Lopes, R.; Wye, L.; Soderblom, L.; Paillou, P.; Aharonson, O.; Zebker, H.; Farr, Tom; Mitri, G.; Kirk, R.; Mitchell, Ken; Notarnicola, C.; Casarano, D.; Ventura, B.

    2010-01-01

    Of more than 400 filled lakes now identified on Titan, the first and largest reported in the southern latitudes is Ontario Lacus, which is dark in both infrared and microwave. Here we describe recent observations including synthetic aperture radar (SAR) images by Cassini's radar instrument (??= 2 cm) and show morphological evidence for active material transport and erosion. Ontario Lacus lies in a shallow depression, with greater relief on the southwestern shore and a gently sloping, possibly wave-generated beach to the northeast. The lake has a closed internal drainage system fed by Earth-like rivers, deltas and alluvial fans. Evidence for active shoreline processes, including the wave-modified lakefront and deltaic deposition, indicates that Ontario is a dynamic feature undergoing typical terrestrial forms of littoral modification. Copyright ?? 2010 by the American Geophysical Union.

  19. Nanofibrous mats layer-by-layer assembled by HTCC/layered silicate composites with in vitro antitumor activity against SMMC-7721 cells.

    PubMed

    Huang, Rong; Zhou, Xue; Liu, Xinqin; Zhang, Qi; Jin, Huan'guang; Shi, Xiaowen; Luo, Wenjing; Deng, Hongbing

    2014-03-01

    Organic rectorite (OREC) was used to prepare the intercalated nanocomposites with N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC), and then the immobilization of the positively charged HTCC-OREC nanocomposites and the negatively charged sodium alginate (ALG) on cellulose nanofibrous mats was performed through layer-by-layer (LBL) technique. Fiber diameter distribution results from Field Emission Scanning Electron Microscopy (FE-SEM) images showed that the average fiber diameter of (HTCC-OREC/ALG)(n) films coating obviously increased from 433 to 608 nm. Moreover, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results further confirmed the interaction between HTCC and OREC and their successful immobilization on cellulose template. MTT assay indicated that the prepared nanofibrous mats exhibited strong inhibitory activity against human hepatocellular carcinoma cells (SMMC-7721) but a little cytotoxic effect on human Chang liver (CCL-13) cells. Furthermore, the experimental results from FE-SEM and Inverted Fluorescence Microscope of SMMC-7721 cells cultured on LBL structured nanofibrous mats demonstrated the significant antitumor activity of prepared samples. The developed approach to immobilize nanocomposites onto polymer nanofibers with controllable thickness may also be utilized to tumor therapy. PMID:24730244

  20. Morphologies of Radio-, X-ray-, and Mid-infrared-selected Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Griffith, Roger L.; Stern, Daniel

    2010-08-01

    We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 active galactic nucleus (AGN) host galaxies from Very Large Array, XMM-Newton, and Spitzer Space Telescope observations of the COSMOS field, respectively. We investigate both quantitative (GALFIT) and qualitative (visual) morphologies of these AGN host galaxies, split by brightness in their selection band. We find that the samples are largely distinct, though extensive overlap exists between certain samples, most particularly for the X-ray- and mid-IR-selected sources with unresolved optical morphologies. We find that the radio-selected AGNs are most distinct, with a very low incidence of having unresolved optical morphologies and a high incidence of being hosted by early-type galaxies. In comparison to X-ray-selected AGNs, mid-IR-selected AGNs have a slightly higher incidence of being hosted by disk galaxies. These morphological results conform to the results of Hickox et al. who studied the colors and large-scale clustering of AGNs and found a general association of radio-selected AGNs with "red sequence" galaxies, mid-IR-selected AGNs with "blue cloud" galaxies, and X-ray-selected AGNs straddling these samples in the "green valley." We also find that optical brightness scales with X-ray and mid-IR brightnesses, while little correlation is evident between optical and radio brightnesses. This suggests that X-ray- and mid-IR-selected AGNs have similar Eddington ratios, while radio-selected AGNs represent a different accretion mechanism with a lower and wider range of Eddington ratios. In the general scenario where AGN activity marks and regulates the transition from late-type disk galaxies into massive elliptical galaxies, this work suggests that the earlier stages are most evident as mid-IR-selected AGNs. Mid-IR emission is less susceptible to

  1. Permafrost and Active Layer Monitoring in the Maritime Antarctic: A Contribution to TSP and ANTPAS projects

    NASA Astrophysics Data System (ADS)

    Vieira, G.; Ramos, M.; Batista, V.; Caselli, A.; Correia, A.; Fragoso, M.; Gruber, S.; Hauck, C.; Kenderova, R.; Lopez-Martinez, J.; Melo, R.; Mendes-Victor, L. A.; Miranda, P.; Mora, C.; Neves, M.; Pimpirev, C.; Rocha, M.; Santos, F.; Blanco, J. J.; Serrano, E.; Trigo, I.; Tome, D.; Trindade, A.

    2008-12-01

    Permafrost and active layer monitoring in the Maritime Antarctic (PERMANTAR) is a Portuguese funded International Project that, in cooperation with the Spanish project PERMAMODEL, will assure the installation and the maintenance of a network of boreholes and active layer monitoring sites, in order to characterize the spatial distribution of the physical and thermal properties of permafrost, as well as the periglacial processes in Livingston and Deception Islands (South Shetlands). The project is part of the International Permafrost Association IPY projects Thermal State of Permafrost (TSP) and Antarctic and Sub-Antarctic Permafrost, Soils and Periglacial Environments (ANTPAS). It contributes to GTN-P and CALM-S networks. The PERMANTAR-PERMAMODEL permafrost and active layer monitoring network includes several boreholes: Reina Sofia hill (since 2000, 1.1m), Incinerador (2000, 2.3m), Ohridski 1 (2008, 5m), Ohridski 2 (2008, 6m), Gulbenkian-Permamodel 1 (2008, 25m) and Gulbenkian- Permamodel 2 (2008, 15m). For active layer monitoring, several CALM-S sites have been installed: Crater Lake (2006), Collado Ramos (2007), Reina Sofia (2007) and Ohridski (2007). The monitoring activities are accompanied by detailed geomorphological mapping in order to identify and map the geomorphic processes related to permafrost or active layer dynamics. Sites will be installed in early 2009 for monitoring rates of geomorphological activity in relation to climate change (e.g. solifluction, rockglaciers, thermokarst). In order to analyse the spatial distribution of permafrost and its ice content, electrical resistivity tomography (ERT), and seismic refraction surveys have been performed and, in early 2009, continuous ERT surveying instrumentation will be installed for monitoring active layer evolution. The paper presents a synthesis of the activities, as well as the results obtained up to the present, mainly relating to ground temperature monitoring and from permafrost characteristics and

  2. Intermittent rhythmic delta activity (IRDA) morphology cannot distinguish between focal and diffuse brain disturbances.

    PubMed

    Neufeld, M Y; Chistik, V; Chapman, J; Korczyn, A D

    1999-03-15

    IRDA (intermittent rhythmic delta activity) is an abnormal generalized EEG pattern that is not specific to any single etiology and can occur with diffuse or focal cerebral disturbances. To determine whether different electrographic features of IRDA and associated EEG findings can differentiate underlying focal from diffuse brain disturbances, we performed a blind analysis of 58 consecutive EEGs with an IRDA pattern, recorded from 1993 until 1996, in which we evaluated posterior background activity, focal slowing and IRDA characteristics (frequency, distribution, duration, symmetry and abundance). The clinical diagnosis, state of consciousness and CT brain findings were retrieved from the patients' hospital records. There were 58 patients (33 females; mean age, 58+/-21 years). Twelve (21%) had only focal brain lesions, while 46 (79%) had diffuse brain abnormalities, (15 diffuse structural, 19 metabolic abnormalities, 12 postictal). Normal consciousness and focal EEG slowing were more frequent in patients with focal abnormalities, however, this was not statistically significant. Of the patients with focal abnormality, 11 (92%) had normal posterior background activity either bilaterally (n=4) or contralateral to the focal lesion (n=7). Bilaterally normal posterior background activity was observed in about 30% in both groups. Bilaterally abnormal posterior background activity was apparent in one patient (8%) with focal brain lesion and in 31 patients (67%) with diffuse brain abnormalities (P<0.0001). There were no significant differences in IRDA electrographic features between the focal group and the group with diffuse brain disturbances. We conclude that IRDA morphology cannot distinguish between focal and diffuse brain abnormalities.

  3. Studies of morphological optical and electrical properties of the MEH-PPV/azo-calix[4]arene composite layers

    NASA Astrophysics Data System (ADS)

    Rouis, A.; Davenas, J.; Bonnamour, I.; Ben Ouada, H.

    2015-10-01

    Thin films of poly[2-methoxy-5-(20-ethylhexyloxy)-1,4 phenylenevinylene] (MEH-PPV), 5,17-bis(4-nitrophenylazo)-26,28-dihydroxy-25,27-di(ethoxycarbonylmethoxy)-calix[4]arene (azo-calix[4]arene) and MEH-PPV doped azo-calix[4]arene, with 30 wt% and 70 wt% doping ratios, were prepared from chloroform solution by spin coating technique on quartz and ITO substrates. Morphological and optical properties of the samples were investigated by scanning electron microscopy (SEM) and UV-visible spectrophotometry techniques, respectively. Further, the charge carrier transport properties and conduction mechanism of the composite MEH-PPV:azo-calix[4]arene thin films based junction were studied by using current-voltage (I-V) characteristics and dielectric spectroscopy technique. I-V characteristic of ITO/MEH-PPV:azo-calix[4]arene/Al devices showed that the space charge limited conduction (SCLC) dominates in the high voltage region. Moreover, frequency dependence of ac conductivity obeys Jonscher's universal power law. Finally, dielectric constant (ε‧), dielectric loss (ε″) and loss tangent (tan δ) were investigated as function of amount of azo-calix[4]arene in the MEH-PPV polymer matrix.

  4. Morphology and phase structures of CW laser-induced oxide layers on iron surface with evolving reflectivity and colors

    NASA Astrophysics Data System (ADS)

    Wu, Taotao; Wang, Lijun; Wei, Chenghua; Zhou, Menglian; He, Minbo; Wu, Lixiong

    2016-11-01

    Laser-induced oxidation will change the laser reflectivity and color features of metal surface. Both changes can be theoretically calculated based on the oxidation kinetics and the optical constants of oxides. For the purpose of calculation, the laser-induced oxidation process of pure polycrystalline iron was studied. Samples with various color features were obtained by continuous wave Nd:YAG fiber laser (1.06 μm) irradiation depending on progressive durations in the intensity of 1.90 W/cm2. The real-time reflectivity and temperature were measured with integral sphere and thermocouples. The irradiated surface morphology and phase structures were characterized by microscope, X-ray diffraction and Raman spectrum. It was found that the first formed magnetite made the surface reflectivity decline rapidly and caused the "positive feedback" effect because of molecular absorption. The later formed hematite oscillated the reflectivity by interference effect. The oxide films were thin, orientated and badly crystallized. The oxidation process was influenced by the grain orientation of the metal substrate. These results made the mechanism of laser-induced oxidation of iron clear and provided available experimental data for accurate modeling of the oxidation kinetics.

  5. Isolation of biologically active and morphologically intact exosomes from plasma of patients with cancer

    PubMed Central

    Hong, Chang-Sook; Funk, Sonja; Muller, Laurent; Boyiadzis, Michael; Whiteside, Theresa L.

    2016-01-01

    Objective Isolation from human plasma of exosomes that retain functional and morphological integrity for probing their protein, lipid and nucleic acid content is a priority for the future use of exosomes as biomarkers. A method that meets these criteria and can be scaled up for patient monitoring is thus desirable. Methods Plasma specimens (1 mL) of patients with acute myeloid leukaemia (AML) or a head and neck squamous cell carcinoma (HNSCC) were differentially centrifuged, ultrafiltered and fractionated by size exclusion chromatography in small disposable columns (mini-SEC). Exosomes were eluted in phosphate-buffered saline and were evaluated by qNano for particle size and counts, morphology by transmission electron microscopy, protein content, molecular profiles by western blots, and for ability to modify functions of immune cells. Results Exosomes eluting in fractions #3–5 had a diameter ranging from 50 to 200 nm by qNano, with the fraction #4 containing the bulk of clean, unaggregated exosomes. The exosome elution profiles remained constant for repeated runs of the same plasma. Larger plasma volumes could be fractionated running multiple mini-SEC columns in parallel. Particle concentrations per millilitre of plasma in #4 fractions of AML and HNSCC were comparable and were higher (p<0.003) than those in normal controls. Isolated AML exosomes co-incubated with normal human NK cells inhibited NKG2D expression levels (p<0.004), and HNSCC exosomes suppressed activation (p<0.01) and proliferation of activated T lymphocytes (p<0.03). Conclusions Mini-SEC allows for simple and reproducible isolation from human plasma of exosomes retaining structural integrity and functional activity. It enables molecular/functional analysis of the exosome content in serial specimens of human plasma for clinical applications. PMID:27018366

  6. Body Morphology, Energy Stores, and Muscle Enzyme Activity Explain Cricket Acoustic Mate Attraction Signaling Variation

    PubMed Central

    Thomson, Ian R.; Darveau, Charles-A.; Bertram, Susan M.

    2014-01-01

    High mating success in animals is often dependent on males signalling attractively with high effort. Since males should be selected to maximize their reproductive success, female preferences for these traits should result in minimal signal variation persisting in the population. However, extensive signal variation persists. The genic capture hypothesis proposes genetic variation persists because fitness-conferring traits depend on an individual's basic processes, including underlying physiological, morphological, and biochemical traits, which are themselves genetically variable. To explore the traits underlying signal variation, we quantified among-male differences in signalling, morphology, energy stores, and the activities of key enzymes associated with signalling muscle metabolism in two species of crickets, Gryllus assimilis (chirper: <20 pulses/chirp) and G. texensis (triller: >20 pulses/chirp). Chirping G. assimilis primarily fuelled signalling with carbohydrate metabolism: smaller individuals and individuals with increased thoracic glycogen stores signalled for mates with greater effort; individuals with greater glycogen phosphorylase activity produced more attractive mating signals. Conversely, the more energetic trilling G. texensis fuelled signalling with both lipid and carbohydrate metabolism: individuals with increased β-hydroxyacyl-CoA dehydrogenase activity and increased thoracic free carbohydrate content signalled for mates with greater effort; individuals with higher thoracic and abdominal carbohydrate content and higher abdominal lipid stores produced more attractive signals. Our findings suggest variation in male reproductive success may be driven by hidden physiological trade-offs that affect the ability to uptake, retain, and use essential nutrients, although the results remain correlational in nature. Our findings indicate that a physiological perspective may help us to understand some of the causes of variation in behaviour. PMID:24608102

  7. Fullerenol Nanoparticles with Structural Activity Induce Variable Intracellular Actin Filament Morphologies.

    PubMed

    Jin, Junjiang; Dong, Ying; Wang, Ying; Xia, Lin; Gu, Weihong; Bai, Xue; Chang, Yanan; Zhang, Mingyi; Chen, Kui; Li, Juan; Zhao, Lina; Xing, Gengmei

    2016-06-01

    Fullerenol nanoparticles are promising for various biological applications; many studies have shown that they induce variable and diverse biological effects including side effects. Separation and purification of two fractions of fullerenols has demonstrated that they have varied chemical structures on the surfaces of their carbon cages. Actin is an important structural protein that is able to transform functional structures under varied physiological conditions. We assessed the abilities of the two fractions of fullerenols to attach to actin and induce variable morphological features in actin filament structures. Specifically the fullerenol fraction with a surface electric charge of -1.913 ± 0.008q (x10(-6) C) has percentages of C-OH and C=O on the carbon cage of 16.14 ± 0.60 and 17.55 ± 0.69. These features allow it to form intermolecular hydrogen bonds with actin at a stoichiometric ratio of four fullerenols per actin subunit. Molecular simulations revealed these specific binding sites and binding modes in atomic details in the interaction between the active fullerenol and actin filament. Conversely, these interactions were not possible for the other fraction of fullerenol with that percentages of C-OH and C=O on the carbon cage were 15.59 ± 0.01 and 1.94 ± 0.11. Neither sample induced appreciable cytotoxicity or acute cell death. After entering cells, active fullerenol binding to actin induces variable morphological features and may transform ATP-actin to ADP-actin. These changes facilitate the binding of ADF/cofilin, allowing cofilin to sever actin filaments to form cofilin/actin/fullerenol rods. Our findings suggest that fullerenol with structural activity binding disturbs actin filament structure, which may inhibit locomotion of cell or induce chronic side effects in to cells. PMID:27319217

  8. The Effects of Oxygen Plasma on the Chemical Composition and Morphology of the Ru Capping Layer of the Extreme Ultraviolet (EUV) Mask Blanks

    SciTech Connect

    Belau, Leonid; Park, Jeong Y.; Liang, Ted; Somorjai, Gabor A.

    2008-06-07

    Contamination removal from extreme ultraviolet (EUV) mask surfaces is one of the most important aspects to improve reliability for the next generation of EUV lithography. We report chemical and morphological changes of the ruthenium (Ru) mask surface after oxygen plasma treatment using surface sensitive analytical methods: X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Chemical analysis of the EUV masks shows an increase in the subsurface oxygen concentration, Ru oxidation and surface roughness. XPS spectra at various photoelectron takeoff angles suggest that the EUV mask surface was covered with chemisorbed oxygen after oxygen plasma treatment. It is proposed that the Kirkendall effect is the most plausible mechanism that explains the Ru surface oxidation. The etching rate of the Ru capping layer by oxygen plasma was estimated to be 1.5 {+-} 0.2 {angstrom}/min, based on TEM cross sectional analysis.

  9. Accurate Morphology Preserving Segmentation of Overlapping Cells based on Active Contours.

    PubMed

    Molnar, Csaba; Jermyn, Ian H; Kato, Zoltan; Rahkama, Vesa; Östling, Päivi; Mikkonen, Piia; Pietiäinen, Vilja; Horvath, Peter

    2016-01-01

    The identification of fluorescently stained cell nuclei is the basis of cell detection, segmentation, and feature extraction in high content microscopy experiments. The nuclear morphology of single cells is also one of the essential indicators of phenotypic variation. However, the cells used in experiments can lose their contact inhibition, and can therefore pile up on top of each other, making the detection of single cells extremely challenging using current segmentation methods. The model we present here can detect cell nuclei and their morphology even in high-confluency cell cultures with many overlapping cell nuclei. We combine the "gas of near circles" active contour model, which favors circular shapes but allows slight variations around them, with a new data model. This captures a common property of many microscopic imaging techniques: the intensities from superposed nuclei are additive, so that two overlapping nuclei, for example, have a total intensity that is approximately double the intensity of a single nucleus. We demonstrate the power of our method on microscopic images of cells, comparing the results with those obtained from a widely used approach, and with manual image segmentations by experts. PMID:27561654

  10. Accurate Morphology Preserving Segmentation of Overlapping Cells based on Active Contours

    PubMed Central

    Molnar, Csaba; Jermyn, Ian H.; Kato, Zoltan; Rahkama, Vesa; Östling, Päivi; Mikkonen, Piia; Pietiäinen, Vilja; Horvath, Peter

    2016-01-01

    The identification of fluorescently stained cell nuclei is the basis of cell detection, segmentation, and feature extraction in high content microscopy experiments. The nuclear morphology of single cells is also one of the essential indicators of phenotypic variation. However, the cells used in experiments can lose their contact inhibition, and can therefore pile up on top of each other, making the detection of single cells extremely challenging using current segmentation methods. The model we present here can detect cell nuclei and their morphology even in high-confluency cell cultures with many overlapping cell nuclei. We combine the “gas of near circles” active contour model, which favors circular shapes but allows slight variations around them, with a new data model. This captures a common property of many microscopic imaging techniques: the intensities from superposed nuclei are additive, so that two overlapping nuclei, for example, have a total intensity that is approximately double the intensity of a single nucleus. We demonstrate the power of our method on microscopic images of cells, comparing the results with those obtained from a widely used approach, and with manual image segmentations by experts. PMID:27561654

  11. Relation between vertical facial morphology and jaw muscle activity in healthy young men.

    PubMed

    Serrao, Graziano; Sforza, Chiarella; Dellavia, Claudia; Antinori, Marco; Ferrario, Virgilio F

    2003-01-01

    The aim of the current investigation was to quantitatively analyze the relation between the activity of masticatory muscles and the inclination of the mandibular plane in a group of 73 healthy white men aged 20-36 years. The three-dimensional coordinates of soft-tissue landmarks gnathion and left and right gonion were digitized using an electromagnetic computerized instrument, the orientation of mandibular plane relative to the true vertical was computed and projected on the anatomical sagittal plane. The electromyographic (EMG) potentials of left and right masseter and temporalis anterior during maximum voluntary teeth clenching were recorded, and the mean EMG amplitude calculated. Two groups of men with opposite facial morphology were then selected: all men with a steep mandibular plane (higher than the mean plus one standard deviation) entered a first group (10 'long face' subjects), while all men with a relatively more horizontal mandibular plane (lower than the mean minus one standard deviation) entered a second group (13 'short face' subjects). Mean EMG potentials computed in the two groups were compared by using Student's t -test for independent samples. All the EMG potentials recorded during maximum voluntary clench in the 'long face' men were lower than that recorded in the 'short face' men, with statistically significant differences for all four analyzed muscles (p < 0.05). In conclusion, a non-invasive three-dimensional method confirmed that facial morphology and muscular function are significantly related, at least in men with a sound stomatognathic apparatus.

  12. Layer-by-layer carbon nanotube bio-templates for in situ monitoring of the metabolic activity of nitrifying bacteria

    NASA Astrophysics Data System (ADS)

    Loh, Kenneth J.; Guest, Jeremy S.; Ho, Genevieve; Lynch, Jerome P.; Love, Nancy G.

    2009-03-01

    Despite the wide variety of effective disinfection and wastewater treatment techniques for removing organic and inorganic wastes, pollutants such as nitrogen remain in wastewater effluents. If left untreated, these nitrogenous wastes can adversely impact the environment by promoting the overgrowth of aquatic plants, depleting dissolved oxygen, and causing eutrophication. Although nitrification/denitrification processes are employed during advanced wastewater treatment, effective and efficient operation of these facilities require information of the pH, dissolved oxygen content, among many other parameters, of the wastewater effluent. In this preliminary study, a biocompatible CNT-based nanocomposite is proposed and validated for monitoring the biological metabolic activity of nitrifying bacteria in wastewater effluent environments (i.e., to monitor the nitrification process). Using carbon nanotubes and a pH-sensitive conductive polymer (i.e., poly(aniline) emeraldine base), a layer-by-layer fabrication technique is employed to fabricate a novel thin film pH sensor that changes its electrical properties in response to variations in ambient pH environments. Laboratory studies are conducted to evaluate the proposed nanocomposite's biocompatibility with wastewater effluent environments and its pH sensing performance.

  13. Rapid electrostatics-assisted layer-by-layer assembly of near-infrared-active colloidal photonic crystals.

    PubMed

    Askar, Khalid; Leo, Sin-Yen; Xu, Can; Liu, Danielle; Jiang, Peng

    2016-11-15

    Here we report a rapid and scalable bottom-up technique for layer-by-layer (LBL) assembling near-infrared-active colloidal photonic crystals consisting of large (⩾1μm) silica microspheres. By combining a new electrostatics-assisted colloidal transferring approach with spontaneous colloidal crystallization at an air/water interface, we have demonstrated that the crystal transfer speed of traditional Langmuir-Blodgett-based colloidal assembly technologies can be enhanced by nearly 2 orders of magnitude. Importantly, the crystalline quality of the resultant photonic crystals is not compromised by this rapid colloidal assembly approach. They exhibit thickness-dependent near-infrared stop bands and well-defined Fabry-Perot fringes in the specular transmission and reflection spectra, which match well with the theoretical calculations using a scalar-wave approximation model and Fabry-Perot analysis. This simple yet scalable bottom-up technology can significantly improve the throughput in assembling large-area, multilayer colloidal crystals, which are of great technological importance in a variety of optical and non-optical applications ranging from all-optical integrated circuits to tissue engineering. PMID:27494632

  14. Transfection activity of layer-by-layer plasmid DNA/poly(ethylenimine) films deposited on PLGA microparticles

    PubMed Central

    Kakade, Sandeep; Manickam, Devika Soundara; Handa, Hitesh; Mao, Guangzhao; Oupický, David

    2009-01-01

    Layer-by-layer (LbL) assemblies of DNA and polycations on the surface of colloidal templates can be used for gene delivery. Plasmid DNA encoding for secreted alkaline phosphatase (SEAP) was used to deposit LbL films with poly(ethylenimine) (PEI) on the surface of polystyrene and poly(lactide-co-glycolide) microparticles. The formation of LBL films was confirmed by zeta potential analysis and fluorescence and atomic force microscopy techniques. The LbL particles were rapidly internalized in a dose-dependent manner by J774.1 murine macrophages. Transfection activity of the LbL particles was evaluated in J774.1 cells using three different doses (5, 10, 25 particle per cell). The levels of SEAP expression increased with increasing dose but were lower than transfection levels mediated by control PEI/DNA polyplexes at corresponding DNA doses. The LbL particles reported here present a promising platform for delivery of DNA to phagocytic cells. PMID:18786622

  15. Rapid electrostatics-assisted layer-by-layer assembly of near-infrared-active colloidal photonic crystals.

    PubMed

    Askar, Khalid; Leo, Sin-Yen; Xu, Can; Liu, Danielle; Jiang, Peng

    2016-11-15

    Here we report a rapid and scalable bottom-up technique for layer-by-layer (LBL) assembling near-infrared-active colloidal photonic crystals consisting of large (⩾1μm) silica microspheres. By combining a new electrostatics-assisted colloidal transferring approach with spontaneous colloidal crystallization at an air/water interface, we have demonstrated that the crystal transfer speed of traditional Langmuir-Blodgett-based colloidal assembly technologies can be enhanced by nearly 2 orders of magnitude. Importantly, the crystalline quality of the resultant photonic crystals is not compromised by this rapid colloidal assembly approach. They exhibit thickness-dependent near-infrared stop bands and well-defined Fabry-Perot fringes in the specular transmission and reflection spectra, which match well with the theoretical calculations using a scalar-wave approximation model and Fabry-Perot analysis. This simple yet scalable bottom-up technology can significantly improve the throughput in assembling large-area, multilayer colloidal crystals, which are of great technological importance in a variety of optical and non-optical applications ranging from all-optical integrated circuits to tissue engineering.

  16. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    SciTech Connect

    Rosikhin, Ahmad Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto

    2015-12-29

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO{sub 2} in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO{sub 2} layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices.

  17. Physical Activity and Prostate Tumor Vessel Morphology: Data from the Health Professionals Follow-up Study.

    PubMed

    Van Blarigan, Erin L; Gerstenberger, John P; Kenfield, Stacey A; Giovannucci, Edward L; Stampfer, Meir J; Jones, Lee W; Clinton, Steven K; Chan, June M; Mucci, Lorelei A

    2015-10-01

    Vigorous activity is associated with lower risk of prostate cancer progression, but the biologic mechanisms are unknown. Exercise affects vascularization of tumors in animal models, and small, irregularly shaped vessels in prostate tumors are associated with fatal prostate cancer. We hypothesized that men who engaged in vigorous activity or brisk walking would have larger, more regularly shaped vessels in their prostate tumors. We prospectively examined whether physical activity was associated with prostate tumor microvessel morphology among 571 men in the Health Professionals Follow-up Study using ordinal logistic regression. Vessel size (μm(2)), vessel lumen regularity (perimeter(2)/4 · Π · area), and microvessel density (number/high-powered field) were ascertained in tumor sections stained for endothelial cell marker CD34. Vigorous activity [metabolic equivalent task (MET) ≥ 6], nonvigorous activity (MET < 6), and walking pace were assessed a median of 14 months before diagnosis. Prostate tumors from men who reported a brisk walking pace (3+ mph) had larger, more regularly shaped blood vessels compared with those of men who walked at a less than brisk pace [vessel regularity OR, 1.59; 95% confidence interval (CI), 1.11-2.27; P value, 0.01; vessel size OR, 1.48; 95% CI, 1.04-2.12; P value, 0.03]. Brisk walking was not associated with microvessel density; total vigorous and nonvigorous activities were not associated with vessel size, shape, or number. Brisk walking may be associated with larger, more regularly shaped vessels in prostate tumors. Additional research elucidating the effect of physical activity on prostate tumor biology is needed. PMID:26276753

  18. Physical activity and prostate tumor vessel morphology: data from the Health Professionals Follow-up Study

    PubMed Central

    Kenfield, Stacey A.; Giovannucci, Edward L.; Stampfer, Meir J.; Jones, Lee W.; Clinton, Steven K.

    2015-01-01

    Vigorous activity is associated with lower risk of prostate cancer progression, but the biologic mechanisms are unknown. Exercise affects vascularization of tumors in animal models, and small, irregularly shaped vessels in prostate tumors are associated with fatal prostate cancer. We hypothesized that men who engaged in vigorous activity or brisk walking would have larger, more regularly shaped vessels in their prostate tumors. We prospectively examined whether physical activity was associated with prostate tumor microvessel morphology among 571 men in the Health Professionals Follow-up Study using ordinal logistic regression. Vessel size (μm2), vessel lumen regularity (perimeter2 / 4 · Π · area), and microvessel density (number per high powered field) were ascertained in tumor sections stained for endothelial cell marker CD34. Vigorous activity [metabolic equivalent task (MET) ≥ 6], non-vigorous activity (MET <6), and walking pace were assessed a median of 14 months prior to diagnosis. Prostate tumors from men who reported a brisk walking pace (3+ mph) had larger, more regularly shaped blood vessels compared to those of men who walked at a less than brisk pace [vessel regularity odds ratio (OR): 1.59; 95% confidence interval (CI): 1.11, 2.27; p-value: 0.01; vessel size OR: 1.48; 95% CI: 1.04, 2.12; p-value: 0.03]. Brisk walking was not associated with microvessel density; total vigorous and non-vigorous activities were not associated with vessel size, shape, or number. Brisk walking may be associated with larger, more regularly shaped vessels in prostate tumors. Additional research elucidating the effect of physical activity on prostate tumor biology is needed. PMID:26276753

  19. Physical Activity and Prostate Tumor Vessel Morphology: Data from the Health Professionals Follow-up Study.

    PubMed

    Van Blarigan, Erin L; Gerstenberger, John P; Kenfield, Stacey A; Giovannucci, Edward L; Stampfer, Meir J; Jones, Lee W; Clinton, Steven K; Chan, June M; Mucci, Lorelei A

    2015-10-01

    Vigorous activity is associated with lower risk of prostate cancer progression, but the biologic mechanisms are unknown. Exercise affects vascularization of tumors in animal models, and small, irregularly shaped vessels in prostate tumors are associated with fatal prostate cancer. We hypothesized that men who engaged in vigorous activity or brisk walking would have larger, more regularly shaped vessels in their prostate tumors. We prospectively examined whether physical activity was associated with prostate tumor microvessel morphology among 571 men in the Health Professionals Follow-up Study using ordinal logistic regression. Vessel size (μm(2)), vessel lumen regularity (perimeter(2)/4 · Π · area), and microvessel density (number/high-powered field) were ascertained in tumor sections stained for endothelial cell marker CD34. Vigorous activity [metabolic equivalent task (MET) ≥ 6], nonvigorous activity (MET < 6), and walking pace were assessed a median of 14 months before diagnosis. Prostate tumors from men who reported a brisk walking pace (3+ mph) had larger, more regularly shaped blood vessels compared with those of men who walked at a less than brisk pace [vessel regularity OR, 1.59; 95% confidence interval (CI), 1.11-2.27; P value, 0.01; vessel size OR, 1.48; 95% CI, 1.04-2.12; P value, 0.03]. Brisk walking was not associated with microvessel density; total vigorous and nonvigorous activities were not associated with vessel size, shape, or number. Brisk walking may be associated with larger, more regularly shaped vessels in prostate tumors. Additional research elucidating the effect of physical activity on prostate tumor biology is needed.

  20. Discrete-Layer Piezoelectric Plate and Shell Models for Active Tip-Clearance Control

    NASA Technical Reports Server (NTRS)

    Heyliger, P. R.; Ramirez, G.; Pei, K. C.

    1994-01-01

    The objectives of this work were to develop computational tools for the analysis of active-sensory composite structures with added or embedded piezoelectric layers. The targeted application for this class of smart composite laminates and the analytical development is the accomplishment of active tip-clearance control in turbomachinery components. Two distinct theories and analytical models were developed and explored under this contract: (1) a discrete-layer plate theory and corresponding computational models, and (2) a three dimensional general discrete-layer element generated in curvilinear coordinates for modeling laminated composite piezoelectric shells. Both models were developed from the complete electromechanical constitutive relations of piezoelectric materials, and incorporate both displacements and potentials as state variables. This report describes the development and results of these models. The discrete-layer theories imply that the displacement field and electrostatic potential through-the-thickness of the laminate are described over an individual layer rather than as a smeared function over the thickness of the entire plate or shell thickness. This is especially crucial for composites with embedded piezoelectric layers, as the actuating and sensing elements within these layers are poorly represented by effective or smeared properties. Linear Lagrange interpolation polynomials were used to describe the through-thickness laminate behavior. Both analytic and finite element approximations were used in the plane or surface of the structure. In this context, theoretical developments are presented for the discrete-layer plate theory, the discrete-layer shell theory, and the formulation of an exact solution for simply-supported piezoelectric plates. Finally, evaluations and results from a number of separate examples are presented for the static and dynamic analysis of the plate geometry. Comparisons between the different approaches are provided when

  1. Active/Passive Control of Sound Radiation from Panels using Constrained Layer Damping

    NASA Technical Reports Server (NTRS)

    Gibbs, Gary P.; Cabell, Randolph H.

    2003-01-01

    A hybrid passive/active noise control system utilizing constrained layer damping and model predictive feedback control is presented. This system is used to control the sound radiation of panels due to broadband disturbances. To facilitate the hybrid system design, a methodology for placement of constrained layer damping which targets selected modes based on their relative radiated sound power is developed. The placement methodology is utilized to determine two constrained layer damping configurations for experimental evaluation of a hybrid system. The first configuration targets the (4,1) panel mode which is not controllable by the piezoelectric control actuator, and the (2,3) and (5,2) panel modes. The second configuration targets the (1,1) and (3,1) modes. The experimental results demonstrate the improved reduction of radiated sound power using the hybrid passive/active control system as compared to the active control system alone.

  2. Morphological and ultrastructural aspects of the activation of avian medullary bone osteoclasts by parathyroid hormone.

    PubMed

    Miller, S C; Bowman, B M; Myers, R L

    1984-02-01

    The activation of physiologically inactive medullary bone osteoclasts by parathyroid hormone (PTH) was examined using light and electron microscopy and histomorphometric methods. Medullary bone osteoclasts are functionally inactive during the avian egg-laying cycle when an egg shell is not being calcified in the shell gland. Japanese quail hens were given 0.5 IU/g PTH and the medullary bone osteoclasts were examined up to 90 min later. Administration of PTH results in rapid changes in osteoclast morphology and ultrastructure. Within 10 min ectoplasmic regions containing condensed-appearing material are evident in areas of the cell adjacent to bone surfaces. In tannic acid-fixed specimens, these ectoplasmic regions contain bundles of filaments extending perpendicularly from the osteoclast plasma membrane into the cytoplasm. It is in these areas that ruffled border development is initiated. Even at 10 min after PTH administration, mineral crystals are seen between the developing cell surface invaginations and folds. By 15 min after PTH administration, ruffled borders have appeared next to bone surfaces. The rapid development of ruffled borders on medullary bone osteoclasts after PTH is confirmed by electron microscope histomorphometry. By 30 min after PTH administration, ruffled borders are well developed and large endocytic vacuoles are beginning to appear in the osteoclast cytoplasm. Light microscope histomorphometric measurements indicate that osteoclasts are also increasing in size and spreading along bone surfaces with time after PTH administration. This study provides a morphologic and ultrastructural description of osteoclast activation by PTH. The results indicate that osteoclasts may effect rapid changes in bone resorption and mineral metabolism due to exogenous PTH in hens.

  3. Effects of surface morphology of ZnO seed layers on growth of ZnO nanostructures prepared by hydrothermal method and annealing.

    PubMed

    Yim, Kwang Gug; Kim, Min Su; Leem, Jae-Young

    2013-05-01

    ZnO nanostructures were grown on Si (111) substrates by a hydrothermal method. Prior to growing the ZnO nanostructures, ZnO seed layers with different post-heat temperatures were prepared by a spin-coating process. Then, the ZnO nanostructures were annealed at 500 degrees C for 20 min under an Ar atmosphere. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out at room temperature (RT) to investigate the structural and optical properties of the as-grown and annealed ZnO nanostructures. The surface morphologies of the seed layers changed from a smooth surface to a mountain chain-like structure as the post-heating temperatures increased. The as-grown and annealed ZnO nanostructures exhibited a strong (002) diffraction peak. Compared to the as-grown ZnO nanostructures, the annealed ZnO nanostructures exhibited significantly strong enhancement in the PL intensity ratio by almost a factor of 2.

  4. Effects of high-flux low-energy ion bombardment on the low-temperature growth morphology of TiN(001) epitaxial layers

    SciTech Connect

    Karr, Brian W.; Cahill, David G.; Petrov, I.; Greene, J. E.

    2000-06-15

    Ultrahigh vacuum scanning tunneling microscopy (STM) is used to characterize the surface morphology of TiN(001) epitaxial layers grown by dc reactive magnetron sputtering at growth temperatures of T{sub s}=650 and T{sub s}=750 degree sign C. An auxiliary anode is used to bias the N{sub 2} plasma and produce a large flux of low-energy N{sub 2}{sup +} ions that bombard the film surface during growth: the ratio of the N{sub 2}{sup +} flux to the Ti growth flux is {approx_equal}25. At ion energies E{sub i} near the threshold for the production of bulk defects (E{sub i}=43 eV and T{sub s}=650 degree sign C), ion bombardment decreases the amplitude of the roughness, decreases the average distance between growth mounds, and reduces the sharpness of grooves between growth mounds. The critical island radius for second layer nucleation R{sub c} is approximately 12 and 17 nm at growth temperatures of 650 and 750 degree sign C respectively; at 650 degree sign C, R{sub c} is reduced to (approx =)10 nm by ion bombardment. (c) 2000 The American Physical Society.

  5. The activity of the Colima volcano and morphological changes in the summit between 2004 and 2007.

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nuñez-Cornu, F. J.; Sanchez-Aguilar, J.; Arriaga, F.

    2007-12-01

    Colima Volcano, located in the West of the Volcanic Mexican Belt, has shown a new cycle of explosive activity beginning May 30 1999, and reaching its maximum in March and April of 2005. This year the explosive activity increased gradually, having the largest event on May 23, when a new dome was created. Hours later this dome was destroyed by a strong explosion, forming an ash column 5.6 km high with subsequent pyroclastic flows that reached a distance of 4.2 km flowing along the ravines of the South sector. On May 30 the most intense explosion in 1999 occurred, when the plume reached heights in excess of 4.4 km above the crater, and piroclastic flows were created. On the same year in July two explosive events occurred of characteristics similar to those in May. These constant explosions caused continuos morphological changes in the summit, the most significant being the collapse of the North and South walls of the crater, in the first week of June of 2005, and the creation of a new crater in July. In 2006 the most significant explosive activity took place during April, May and July, when the eruptive columns reached heights of more than 1500 meters above the crater, occasionally forming small pyroclastic flows. In May of 2007 morphological changes were observed in the summit. Among them a crater explosion on the East side, a new dome was formed on the West side, with 20 m in high and 50 m in diameter. The explosive events continue to date, but they have diminished in size and intensity. This activity was similar to the one observed in 1902-1903 and reported by Severo Diaz (1906), but without reaching the maximum levels of activity reported for 1903, where it had levels of three to five maximum explosive events per day. The photographs and the digital mapping have provided detailed information to quantify the dynamic evolution of the volcanic structures that developed on the summit of the volcano in the course of the last for years.

  6. Activation and aponeurosis morphology affect in vivo muscle tissue strains near the myotendinous junction.

    PubMed

    Fiorentino, Niccolo M; Epstein, Frederick H; Blemker, Silvia S

    2012-02-23

    Hamstring strain injury is one of the most common injuries in athletes, particularly for sports that involve high speed running. The aims of this study were to determine whether muscle activation and internal morphology influence in vivo muscle behavior and strain injury susceptibility. We measured tissue displacement and strains in the hamstring muscle injured most often, the biceps femoris long head muscle (BFLH), using cine DENSE dynamic magnetic resonance imaging. Strain measurements were used to test whether strain magnitudes are (i) larger during active lengthening than during passive lengthening and (ii) larger for subjects with a relatively narrow proximal aponeurosis than a wide proximal aponeurosis. Displacement color maps showed higher tissue displacement with increasing lateral distance from the proximal aponeurosis for both active lengthening and passive lengthening, and higher tissue displacement for active lengthening than passive lengthening. First principal strain magnitudes were averaged in a 1cm region near the myotendinous junction, where injury is most frequently observed. It was found that strains are significantly larger during active lengthening (0.19 SD 0.09) than passive lengthening (0.13 SD 0.06) (p<0.05), which suggests that elevated localized strains may be a mechanism for increased injury risk during active as opposed to passive lengthening. First principal strains were higher for subjects with a relatively narrow aponeurosis width (0.26 SD 0.15) than wide (0.14 SD 0.04) (p<0.05). This result suggests that athletes who have BFLH muscles with narrow proximal aponeuroses may have an increased risk for BFLH strain injuries.

  7. Active layer thermal monitoring at Fildes Peninsula, King George Island, Maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Michel, R. F. M.; Schaefer, C. E. G. R.; Simas, F. N. B.; Francelino M., R.; Fernandes-Filho, E. I.; Lyra, G. B.; Bockheim, J. G.

    2014-07-01

    International attention to the climate change phenomena has grown in the last decade; the active layer and permafrost are of great importance in understanding processes and future trends due to their role in energy flux regulation. The objective of the this paper is to present active layer temperature data for one CALM-S site located at Fildes Peninsula, King George Island, Maritime Antarctica over an fifth seven month period (2008-2012). The monitoring site was installed during the summer of 2008 and consists of thermistors (accuracy of ± 0.2 °C), arranged vertically with probes at different depths, recording data at hourly intervals in a~high capacity data logger. A series of statistical analysis were performed to describe the soil temperature time series, including a linear fit in order to identify global trend and a series of autoregressive integrated moving average (ARIMA) models were tested in order to define the best fit for the data. The controls of weather on the thermal regime of the active layer have been identified, providing insights about the influence of climate chance over the permafrost. The active layer thermal regime in the studied period was typical of periglacial environment, with extreme variation at the surface during summer resulting in frequent freeze and thaw cycles. The active layer thickness (ALT) over the studied period showed variability related to different annual weather conditions, reaching a maximum of 117.5 cm in 2009. The ARIMA model was considered appropriate to treat the dataset, enabling more conclusive analysis and predictions when longer data sets are available. Despite the variability when comparing temperature readings and active layer thickness over the studied period, no warming trend was detected.

  8. Active-layer thermal monitoring on the Fildes Peninsula, King George Island, maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Michel, R. F. M.; Schaefer, C. E. G. R.; Simas, F. M. B.; Francelino, M. R.; Fernandes-Filho, E. I.; Lyra, G. B.; Bockheim, J. G.

    2014-12-01

    International attention to climate change phenomena has grown in the last decade; the active layer and permafrost are of great importance in understanding processes and future trends due to their role in energy flux regulation. The objective of this paper is to present active-layer temperature data for one Circumpolar Active Layer Monitoring South hemisphere (CALM-S) site located on the Fildes Peninsula, King George Island, maritime Antarctica over an 57-month period (2008-2012). The monitoring site was installed during the summer of 2008 and consists of thermistors (accuracy of ±0.2 °C), arranged vertically with probes at different depths, recording data at hourly intervals in a high-capacity data logger. A series of statistical analyses was performed to describe the soil temperature time series, including a linear fit in order to identify global trends, and a series of autoregressive integrated moving average (ARIMA) models was tested in order to define the best fit for the data. The affects of weather on the thermal regime of the active layer have been identified, providing insights into the influence of climate change on permafrost. The active-layer thermal regime in the studied period was typical of periglacial environments, with extreme variation in surface during the summer resulting in frequent freeze and thaw cycles. The active-layer thickness (ALT) over the studied period shows a degree of variability related to different annual weather conditions, reaching a maximum of 117.5 cm in 2009. The ARIMA model could describe the data adequately and is an important tool for more conclusive analysis and predictions when longer data sets are available. Despite the variability when comparing temperature readings and ACT over the studied period, no trend can be identified.

  9. Activation Layer Stabilization of High Polarization Photocathodes in Sub-Optimal RF Gun Environments

    SciTech Connect

    Gregory A. Mulhollan

    2010-11-16

    Specific activation recipes for bulk, 100 nm thick MBE grown and high polarization III-V photocathode material have been developed which mitigate the effects of exposure to background gasses. Lifetime data using four representative gasses were acquired for bulk GaAs, 100 nm unstrained GaAs and strained superlattice GaAs/GaAsP, all activated both with Cs and then Cs and Li (bi-alkali). Each photoemitter showed marked resilience improvement when activated using the bi-alkali recipe compared to the standard single alkali recipe. A dual alkali activation system at SLAC was constructed, baked and commissioned with the purpose of performing spin-polarization measurements on electrons emitted from the bi-alkali activated surfaces. An end station at SSRL was configured with the required sources for energy resolved photoemission measurements on the bi-alkali activated and CO2 dosed surfaces. The bi-alkali recipes were successfully implemented at SLAC/SSRL. Measurements at SLAC of the photoelectron spin-polarization from the modified activation surface showed no sign of a change in value compared to the standard activated material, i.e., no ill effects. Analysis of photoemission data indicates that the addition of Li to the activation layer results in a multi-layer structure. The presence of Li in the activation layer also acts as an inhibitor to CO2 absorption, hence better lifetimes in worse vacuum were achieved. The bi-alkali activation has been tested on O2 activated GaAs for comparison with NF3 activated surfaces. Comparable resilience to CO2 exposure was achieved for the O2 activated surface. An RF PECVD amorphous silicon growth system was modified to allow high temperature heat cleaning of GaAs substrates prior to film deposition. Growth versus thickness data were collected. Very thin amorphous silicon germanium layers were optimized to exhibit good behavior as an electron emitter. Growth of the amorphous silicon germanium films on the above substrates was fine tuned

  10. MAPLE prepared heterostructures with arylene based polymer active layer for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Stanculescu, F.; Rasoga, O.; Catargiu, A. M.; Vacareanu, L.; Socol, M.; Breazu, C.; Preda, N.; Socol, G.; Stanculescu, A.

    2015-05-01

    This paper presents some studies about the preparation by matrix-assisted pulsed laser evaporation (MAPLE) technique of heterostructures with single layer of arylene based polymer, poly[N-(2-ethylhexyl)2.7-carbazolyl vinylene]/AMC16 and poly[N-(2-ethylhexyl)2.7-carbazolyl 1.4-phenylene ethynylene]/AMC22, and with layers of these polymers mixed with Buckminsterfullerene/C60 in the weight ratio of 1:2 (AMC16:C60) and 1:3 (AMC22:C60). The deposited layers have been characterized by spectroscopic (UV-Vis-NIR, PL, FTIR) and microscopic (SEM, AFM) methods. The effect of the polymer particularities on the optical and electrical properties of the structures based on polymer and polymer:C60 mixed layer has been analyzed. The study of the electrical properties has revealed typical solar cell behavior for the heterostructure prepared by MAPLE on glass/ITO/PEDOT-PSS with AMC16, AMC22 and AMC22:C60 layer, confirming that this method is adequate for the preparation of polymeric and mixed active layers for solar cells applications. The highest photovoltaic effect was shown by the solar cell structure realized with single layer of AMC16 polymer: glass/ITO/PEDOT-PSS/AMC16/Al.

  11. Morphology, stratigraphy, and mineralogical composition of a layered formation covering the plateaus around Valles Marineris, Mars: Implications for its geological history

    NASA Astrophysics Data System (ADS)

    Le Deit, L.; Bourgeois, O.; Mège, D.; Hauber, E.; Le Mouélic, S.; Massé, M.; Jaumann, R.; Bibring, J.-P.

    2010-08-01

    An extensive layered formation covers the high plateaus around Valles Marineris. Mapping based on HiRISE, CTX and HRSC images reveals these layered deposits (LDs) crop out north of Tithonium Chasma, south of Ius Chasma, around West Candor Chasma, and southwest of Juventae Chasma and Ganges Chasma. The estimated area covered by LDs is ˜42,300 km 2. They consist of a series of alternating light and dark beds, a 100 m in total thickness that is covered by a dark unconsolidated mantle possibly resulting from their erosion. Their stratigraphic relationships with the plateaus and the Valles Marineris chasmata indicate that the LDs were deposited during the Early- to Late Hesperian, and possibly later depending on the region, before the end of the backwasting of the walls near Juventae Chasma, and probably before Louros Valles sapping near Ius Chasma. Their large spatial coverage and their location mainly on highly elevated plateaus lead us to conclude that LDs correspond to airfall dust and/or volcanic ash. The surface of LDs is characterized by various morphological features, including lobate ejecta and pedestal craters, polygonal fractures, valleys and sinuous ridges, and a pitted surface, which are all consistent with liquid water and/or water ice filling the pores of LDs. LDs were episodically eroded by fluvial processes and were possibly modified by sublimation processes. Considering that LDs correspond to dust and/or ash possibly mixed with ice particles in the past, LDs may be compared to Dissected Mantle Terrains currently observed in mid- to high latitudes on Mars, which correspond to a mantle of mixed dust and ice that is partially or totally dissected by sublimation. The analysis of CRISM and OMEGA hyperspectral data indicates that the basal layer of LDs near Ganges Chasma exhibits spectra with absorption bands at ˜1.4 μm, and ˜1.9 μm and a large deep band between ˜2.21 and ˜2.26 μm that are consistent with previous spectral analysis in other regions

  12. Efficacy of different final irrigant activation protocols on smear layer removal by EDTA and citric acid.

    PubMed

    Herrera, Daniel R; Santos, Zarina T; Tay, Lidia Y; Silva, Emmanuel J; Loguercio, Alessandro D; Gomes, Brenda P F A

    2013-04-01

    The aim of this study was to evaluate the influence of different activation protocols for chelating agents used after chemo-mechanical preparation (CMP), for smear layer (SL) removal. Forty-five single-rooted human premolars with straight canals and fully formed apex were selected. The specimens were randomly divided into three groups depending on the chelating agent used for smear layer removal: distilled water (DW, control group); 17% ethylenediaminetetraacetic acid (EDTA); and 10% citric acid (CA). Each group was further divided into three subgroups according to the activation protocol used: no-activation (NA), manual dynamic activation (MDA), or sonic activation (SA). After CMP, all specimens were sectioned and processed for observation of the apical thirds by using scanning electron microscopy (SEM). Two calibrated evaluators attributed scores to each specimen. The differences between activation protocols were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Friedman and Wilcoxon signed rank tests were used for comparison between each root canal third. When chelating agents were activated, either by MDA or SA, it was obtained the best cleaning results with no significant difference between EDTA and CA (P > 0.05). Sonic activation showed the best results when root canal thirds were analyzed, in comparison to MDA and NA groups (P < 0.05). The activation of chelating agents, independent of the protocol used, benefits smear layer removal from root canals.

  13. Antimicrobial Activity Evaluation on Silver Doped Hydroxyapatite/Polydimethylsiloxane Composite Layer

    PubMed Central

    Ciobanu, C. S.; Groza, A.; Iconaru, S. L.; Popa, C. L.; Chapon, P.; Chifiriuc, M. C.; Hristu, R.; Stanciu, G. A.; Negrila, C. C.; Ghita, R. V.; Ganciu, M.; Predoi, D.

    2015-01-01

    The goal of this study was the preparation, physicochemical characterization, and microbiological evaluation of novel hydroxyapatite doped with silver/polydimethylsiloxane (Ag:HAp-PDMS) composite layers. In the first stage, the deposition of polydimethylsiloxane (PDMS) polymer layer on commercially pure Si disks has been produced in atmospheric pressure corona discharges. Finally, the new silver doped hydroxyapatite/polydimethylsiloxane composite layer has been obtained by the thermal evaporation technique. The Ag:HAp-PDMS composite layers were characterized by various techniques, such as Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The antimicrobial activity of the Ag:HAp-PDMS composite layer was assessed against Candida albicans ATCC 10231 (ATCC—American Type Culture Collection) by culture based and confirmed by SEM and Confocal Laser Scanning Microscopy (CLSM) methods. This is the first study reporting the antimicrobial effect of the Ag:HAp-PDMS composite layer, which proved to be active against Candida albicans biofilm embedded cells. PMID:26504849

  14. Antimicrobial Activity Evaluation on Silver Doped Hydroxyapatite/Polydimethylsiloxane Composite Layer.

    PubMed

    Ciobanu, C S; Groza, A; Iconaru, S L; Popa, C L; Chapon, P; Chifiriuc, M C; Hristu, R; Stanciu, G A; Negrila, C C; Ghita, R V; Ganciu, M; Predoi, D

    2015-01-01

    The goal of this study was the preparation, physicochemical characterization, and microbiological evaluation of novel hydroxyapatite doped with silver/polydimethylsiloxane (Ag:HAp-PDMS) composite layers. In the first stage, the deposition of polydimethylsiloxane (PDMS) polymer layer on commercially pure Si disks has been produced in atmospheric pressure corona discharges. Finally, the new silver doped hydroxyapatite/polydimethylsiloxane composite layer has been obtained by the thermal evaporation technique. The Ag:HAp-PDMS composite layers were characterized by various techniques, such as Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-ray photoelectron spectroscopy (XPS). The antimicrobial activity of the Ag:HAp-PDMS composite layer was assessed against Candida albicans ATCC 10231 (ATCC-American Type Culture Collection) by culture based and confirmed by SEM and Confocal Laser Scanning Microscopy (CLSM) methods. This is the first study reporting the antimicrobial effect of the Ag:HAp-PDMS composite layer, which proved to be active against Candida albicans biofilm embedded cells. PMID:26504849

  15. Link of local micro-morphology diversity with variability of the DAN active mode measurements along the rover Curiosity traverse in the Gale crater

    NASA Astrophysics Data System (ADS)

    Kuzmin, Ruslan

    2014-05-01

    The rover Curiosity traverse from the Yellowknife Bay (YKB) up to the Darwin outcrop area (DOA) crossed mainly the Smooth Hummocky unit and in places - the Rugged unit spots. Whereas the Smooth Hummocky unit is characterized by low surface roughness and uniform tone, the Rugged unit is typically represented by outcrops with rougher surface texture. As it well seen based on Navcam and Mastcam images, the modern dominant micro-morphology of the landing site area is characteristic of surface shaped by strong aeolian deflation processes. Blowout shallow depressions and wind erosion remnants (in forms of mounds and ridges) are widespread along the rover traverse. As result, in most cases the surface texture of the regolith in the traverse area represents a desert pavement - a surface of tightly packed gravels and pebbles that armor lower more fine material below. Conglomerate outcrops are also exposed within both the Smooth Hummocky unit and the Rugged unit spots and aeolian accumulation features (aeolian drifts, small dunes and ripples) are relatively rare occurring mainly on local leeward slopes of mounds and ridges. During the traverse from the YKB to DOA the Dynamic Albedo of Neutrons (DAN) instrument conducted 140 local active mode measurements of the thermal and epithermal neutrons counts in the top ~60 cm of the Martian subsurface with horizontal sensing "footprint" of about 3 m. Based on the active mode of the DAN measurements it was found that the thermal and epithermal neutron counts measured along the rover traverse show distinct variability from one rover location to another. It was found that a water equivalent of H (WEH) distribution in 60-cm subsurface layer along the rover traverse are fit by a two-layers model, where the top layer (with varied thickness) has less WEH ("dry") than the bottom layer ("wet"). It is distinct that spatial distribution of WEH within the top layer (1-2.5 wt. %) are chiefly homogeneous along the traverse, whereas the range of

  16. Morphology transition of raft-model membrane induced by osmotic pressure: Formation of double-layered vesicle similar to an endo- and/or exocytosis

    NASA Astrophysics Data System (ADS)

    Onai, Teruaki; Hirai, Mitsuhiro

    2010-10-01

    The effect of osmotic pressure on the structure of large uni-lamellar vesicle (LUV) of the lipid mixtures of monosialoganglioside (GM1)-cholesterol-dioleoyl-phosphatidylcholine (DOPC) was studies by using wide-angle X-ray scattering (WAXS) method. The molar ratios of the mixtures were 0.1/0.1/1, 0/0.1/1, and 0/0/1. The ternary lipid mixture is a model of lipid rafts. The value of osmotic pressure was varied from 0 to 4.16×105 N/m2 by adding the polyvinylpyrrolidone (PVP) in the range from 0 to 25 % w/v. In the case of the mixtures without GM1, the rise of the osmotic pressure just enhances the multi-lamellar stacking with deceasing the inter-lamellar spacing. On the other hand, the mixture containing GM1 shows the structural transition from a uni-lamellar vesicle to a double-layered vesicle (a liposome including a smaller one inside) by the rise of osmotic pressure. In this morphology transition the total surface area of the double-layered vesicle is mostly as same as that of the LUV at the initial state. The polar head region of GM1 is bulky and highly hydrophilic due to the oligosaccharide chain containing a sialic acid residue. Then, the present results suggest that the existence of GM1 in the outer-leaflet of the LUV is essentially important for such a double-layered vesicle formation. Alternatively, a phenomenon similar to an endo- and/or exocytosis in cells can be caused simply by a variation of osmotic pressure.

  17. Plasma Corticosterone Activates SGK1 and Induces Morphological Changes in Oligodendrocytes in Corpus Callosum

    PubMed Central

    Miyata, Shingo; Koyama, Yoshihisa; Takemoto, Kana; Yoshikawa, Keiko; Ishikawa, Toshiko; Taniguchi, Manabu; Inoue, Kiyoshi; Aoki, Miwa; Hori, Osamu; Katayama, Taiichi; Tohyama, Masaya

    2011-01-01

    Repeated stressful events are known to be associated with onset of depression. Further, stress activates the hypothalamic–pituitary–adrenocortical (HPA) system by elevating plasma cortisol levels. However, little is known about the related downstream molecular pathway. In this study, by using repeated water-immersion and restraint stress (WIRS) as a stressor for mice, we attempted to elucidate the molecular pathway induced by elevated plasma corticosterone levels. We observed the following effects both, in vivo and in vitro: (1) repeated exposure to WIRS activates the 3-phosphoinositide-dependent protein kinase (PDK1)–serum glucocorticoid regulated kinase (SGK1)–N-myc downstream-regulated gene 1 (NDRG1)–adhesion molecule (i.e., N-cadherin, α-catenin, and β-catenin) stabilization pathway via an increase in plasma corticosterone levels; (2) the activation of this signaling pathway induces morphological changes in oligodendrocytes; and (3) after recovery from chronic stress, the abnormal arborization of oligodendrocytes and depression-like symptoms return to the control levels. Our data strongly suggest that these abnornalities of oligodendrocytes are possibly related to depression-like symptoms. PMID:21655274

  18. Modeling the gain and bandwidth of submicron active layer n+-i-p+ avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Majumder, Kanishka; Das, N. R.

    2012-10-01

    The electron initiated avalanche gain and bandwidth are calculated for thin submicron GaAs n+-i-p+ avalanche photodiode. A model is used to estimate the avalanche build-up of carriers in the active multiplication layer considering the dead-space effect. In the model, the carriers are identified both by their energy and position in the multiplication region. The excess energy of the carriers above threshold is assumed to be equally distributed among the carriers generated after impact ionization. The gain versus bias and bandwidth versus gain characteristics of the device are also demonstrated for different active layer thicknesses of the APD.

  19. Microbial diversity of active layer and permafrost in an acidic wetland from the Canadian High Arctic.

    PubMed

    Wilhelm, Roland C; Niederberger, Thomas D; Greer, Charles; Whyte, Lyle G

    2011-04-01

    The abundance and structure of archaeal and bacterial communities from the active layer and the associated permafrost of a moderately acidic (pH < 5.0) High Arctic wetland (Axel Heiberg Island, Nunavut, Canada) were investigated using culture- and molecular-based methods. Aerobic viable cell counts from the active layer were ∼100-fold greater than those from the permafrost (2.5 × 10(5) CFU·(g soil dry mass)(-1)); however, a greater diversity of isolates were cultured from permafrost, as determined by 16S rRNA gene sequencing. Isolates from both layers demonstrated growth characteristics of a psychrotolerant, halotolerant, and acidotolerant community. Archaea constituted 0.1% of the total 16S rRNA gene copy number and, in the 16S rRNA gene clone library, predominantly (71% and 95%) consisted of Crenarchaeota related to Group I. 1b. In contrast, bacterial communities were diverse (Shannon's diversity index, H = ∼4), with Acidobacteria constituting the largest division of active layer clones (30%) and Actinobacteria most abundant in permafrost (28%). Direct comparisons of 16S rRNA gene sequence data highlighted significant differences between the bacterial communities of each layer, with the greatest differences occurring within Actinobacteria. Comparisons of 16S rRNA gene sequences with those from other Arctic permafrost and cold-temperature wetlands revealed commonly occurring taxa within the phyla Chloroflexi, Acidobacteria, and Actinobacteria (families Intrasporangiaceae and Rubrobacteraceae). PMID:21491982

  20. Study of dopant activation in biaxially compressively strained SiGe layers using excimer laser annealing

    NASA Astrophysics Data System (ADS)

    Luong, G. V.; Wirths, S.; Stefanov, S.; Holländer, B.; Schubert, J.; Conde, J. C.; Stoica, T.; Breuer, U.; Chiussi, S.; Goryll, M.; Buca, D.; Mantl, S.

    2013-05-01

    Excimer Laser Annealing (ELA) with a wavelength of 248 nm is used to study doping of biaxialy compressively strained Si1-xGex/Si heterostructures. The challenge is to achieve a high activation of As in SiGe, while conserving the elastic strain and suppressing dopant diffusion. Doping of 20 nm Si0.64Ge0.36 layers by ion implantation of 1 × 1015 As+/cm2 and subsequent laser annealing using single 20 ns pulse with an energy density of 0.6 J/cm2 leads to an As activation of about 20% and a sheet resistance of 650 Ω/sq. At this laser energy density, the entire SiGe layer melts and the subsequent fast recrystallization on a nanosecond time scale allows high As incorporation into the lattice. Moreover, using these annealing parameters, the SiGe layer exhibits epitaxial regrowth with negligible strain relaxation. ELA at energy densities greater than 0.6 J/cm2 resembles Pulsed Lased Induced Epitaxy, leading to an intermixing of the SiGe layer with the Si substrate, thus to thicker single-crystalline strained SiGe layers with sheet resistance down to 62 Ω/sq. Effects of energy densities on composition, crystal quality, activation of As and co-doping with B are discussed and related to the spatial and temporal evolution of the temperature in the irradiated zone, as simulated by Finite Element Methods.

  1. Electrospun nanofiber layers with incorporated photoluminescence indicator for chromatography and detection of ultraviolet-active compounds.

    PubMed

    Kampalanonwat, Pimolpun; Supaphol, Pitt; Morlock, Gertrud E

    2013-07-19

    For the first time, electrospun nanofiber phases were fabricated with manganese-activated zinc silicate as photoluminescent indicator (UV254) to transfer and enlarge its application to the field of UV-active compounds. By integration of such an indicator, UV-active compounds got visible on the chromatogram. The separation of 7 preservatives and a beverage sample were studied on the novel luminescent polyacrylonitrile layers. The mat thickness and mean fiber diameters were calculated for additions of different UV254 indicator concentrations. The separation efficiency on the photoluminescent layers was characterized by comparison to HPTLC layers and calculation of the plate numbers and resolutions. Some benefits were the reduction in migration distance (3cm), migration time (12min), analyte (10-nL volumes) and mobile phase volumes (1mL). As ultrathin stationary phase, such layers are suited for their integration into the Office Chromatography concept. For the first time, electrospun nanofiber layers were hyphenated with mass spectrometry and the confirmation of compounds was successfully performed using the elution-head based TLC-MS Interface.

  2. Microbial Activity in Active and Upper Permafrost Layers in Axel Heiberg Island

    NASA Astrophysics Data System (ADS)

    Vishnivetskaya, T. A.; Allan, J.; Cheng, K.; Chourey, K.; Hettich, R. L.; Layton, A.; Liu, X.; Murphy, J.; Mykytczuk, N. C.; Phelps, T. J.; Pfiffner, S. M.; Saarunya, G.; Stackhouse, B. T.; Whyte, L.; Onstott, T. C.

    2011-12-01

    Data on microbial communities and their metabolic activity in Arctic wetlands and underlying permafrost sediments is lacking. Samples were collected from different depths of a cryosol (D1, D2) and upper permafrost (D3) at the Axel Heiberg Island in July 2009. Upper cryosol has lower H2O but higher C and N content when compared to deeper horizons including upper permafrost layer. Deep cryosol and upper permafrost contained SO42- (155 and 132 ppm) and NO3- (0.12 and 0.10 ppm), respectively. The phylogenetic analyses of the environmental 16S rRNA genes showed the putative SRB were more abundant in permafrost (8%) than in cryosols, D1 (0.2%) and D2 (1.1%). Putative denitrifying bacteria varied along depth with near 0.1% in D1 and a significant increase in D2 (2.7%) and D3 (2.2%). Methanogens were not detected; methanotrophs were present at low levels in D3 (1%). Two sets of microcosms were set up. Firstly, anaerobic microcosms, amended with 10 mM glucose, sulfate or nitrate, were cultivated at varying temperatures (15o, 6o, and 0o C) for 10 months. Metabolic activity was monitored by measuring CO2 and CH4 every 3 months. A total of 89.5% of the D3-originated microcosms showed higher activity in comparison to cryosols in first 3 months. CH4 was not detected in these microcosms, whereas CO2 production was higher at 15o C or with glucose. Metaproteomics analyses of microcosms with higher levels of CO2 production indicated the presence of stress responsive proteins (e.g. DnaK, GroEL) and proteins essential for energy production and survival under carbon starvation (e.g. F0F1 ATP synthase, acyl-CoA dehydrogenase). These proteins have been previously shown to be up-regulated at low temperatures by permafrost bacteria. Metaproteomics data based on the draft sequences indicated the presence of proteins from the genera Bradyrhizobium, Sphingomonas, Lysinibacillus and Methylophilaceae and these bacteria were also detected by pyrosequencing. Secondly, a duplicate set of anaerobic

  3. Activity induces traveling waves, vortices and spatiotemporal chaos in a model actomyosin layer

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Rajesh; Jülicher, Frank

    2016-02-01

    Inspired by the actomyosin cortex in biological cells, we investigate the spatiotemporal dynamics of a model describing a contractile active polar fluid sandwiched between two external media. The external media impose frictional forces at the interface with the active fluid. The fluid is driven by a spatially-homogeneous activity measuring the strength of the active stress that is generated by processes consuming a chemical fuel. We observe that as the activity is increased over two orders of magnitude the active polar fluid first shows spontaneous flow transition followed by transition to oscillatory dynamics with traveling waves and traveling vortices in the flow field. In the flow-tumbling regime, the active polar fluid also shows transition to spatiotemporal chaos at sufficiently large activities. These results demonstrate that level of activity alone can be used to tune the operating point of actomyosin layers with qualitatively different spatiotemporal dynamics.

  4. Activity induces traveling waves, vortices and spatiotemporal chaos in a model actomyosin layer

    PubMed Central

    Ramaswamy, Rajesh; Jülicher, Frank

    2016-01-01

    Inspired by the actomyosin cortex in biological cells, we investigate the spatiotemporal dynamics of a model describing a contractile active polar fluid sandwiched between two external media. The external media impose frictional forces at the interface with the active fluid. The fluid is driven by a spatially-homogeneous activity measuring the strength of the active stress that is generated by processes consuming a chemical fuel. We observe that as the activity is increased over two orders of magnitude the active polar fluid first shows spontaneous flow transition followed by transition to oscillatory dynamics with traveling waves and traveling vortices in the flow field. In the flow-tumbling regime, the active polar fluid also shows transition to spatiotemporal chaos at sufficiently large activities. These results demonstrate that level of activity alone can be used to tune the operating point of actomyosin layers with qualitatively different spatiotemporal dynamics. PMID:26877263

  5. The Effect of Cellulose Crystal Structure and Solid-State Morphology on the Activity of Cellulases

    SciTech Connect

    Stipanovic, Arthur J

    2014-11-17

    Consistent with the US-DOE and USDA “Roadmap” objective of producing ethanol and chemicals from cellulosic feedstocks more efficiently, a three year research project entitled “The Effect of Cellulose Crystal Structure and Solid-State Morphology on the Activity of Cellulases” was initiated in early 2003 under DOE sponsorship (Project Number DE-FG02-02ER15356). A three year continuation was awarded in June 2005 for the period September 15, 2005 through September 14, 2008. The original goal of this project was to determine the effect of cellulose crystal structure, including allomorphic crystalline form (Cellulose I, II, III, IV and sub-allomorphs), relative degree of crystallinity and crystallite size, on the activity of different types of genetically engineered cellulase enzymes to provide insight into the mechanism and kinetics of cellulose digestion by “pure” enzymes rather than complex mixtures. We expected that such information would ultimately help enhance the accessibility of cellulose to enzymatic conversion processes thereby creating a more cost-effective commercial process yielding sugars for fermentation into ethanol and other chemical products. Perhaps the most significant finding of the initial project phase was that conversion of native bacterial cellulose (Cellulose I; BC-I) to the Cellulose II (BC-II) crystal form by aqueous NaOH “pretreatment” provided an increase in cellulase conversion rate approaching 2-4 fold depending on enzyme concentration and temperature, even when initial % crystallinity values were similar for both allomorphs.

  6. Methyl jasmonate affects morphology, number and activity of endoplasmic reticulum bodies in Raphanus sativus root cells.

    PubMed

    Gotté, Maxime; Ghosh, Rajgourab; Bernard, Sophie; Nguema-Ona, Eric; Vicré-Gibouin, Maïté; Hara-Nishimura, Ikuko; Driouich, Azeddine

    2015-01-01

    The endoplasmic reticulum (ER) bodies are ER-derived structures that are found in Brassicaceae species and thought to play a role in defense. Here, we have investigated the occurrence, distribution and function of ER bodies in root cells of Raphanus sativus using a combination of microscopic and biochemical methods. We have also assessed the response of ER bodies to methyl jasmonate (MeJA), a phytohormone that mediates plant defense against wounding and pathogens. Our results show that (i) ER bodies do occur in different root cell types from the root cap region to the differentiation zone; (ii) they do accumulate a PYK10-like protein similar to the major marker protein of ER bodies that is involved in defense in Arabidopsis thaliana; and (iii) treatment of root cells with MeJA causes a significant increase in the number of ER bodies and the activity of β-glucosidases. More importantly, MeJA was found to induce the formation of very long ER bodies that results from the fusion of small ones, a phenomenon that has not been reported in any other study so far. These findings demonstrate that MeJA impacts the number and morphology of functional ER bodies and stimulates ER body enzyme activities, probably to participate in defense responses of radish root. They also suggest that these structures may provide a defensive system specific to root cells.

  7. Methyl jasmonate affects morphology, number and activity of endoplasmic reticulum bodies in Raphanus sativus root cells.

    PubMed

    Gotté, Maxime; Ghosh, Rajgourab; Bernard, Sophie; Nguema-Ona, Eric; Vicré-Gibouin, Maïté; Hara-Nishimura, Ikuko; Driouich, Azeddine

    2015-01-01

    The endoplasmic reticulum (ER) bodies are ER-derived structures that are found in Brassicaceae species and thought to play a role in defense. Here, we have investigated the occurrence, distribution and function of ER bodies in root cells of Raphanus sativus using a combination of microscopic and biochemical methods. We have also assessed the response of ER bodies to methyl jasmonate (MeJA), a phytohormone that mediates plant defense against wounding and pathogens. Our results show that (i) ER bodies do occur in different root cell types from the root cap region to the differentiation zone; (ii) they do accumulate a PYK10-like protein similar to the major marker protein of ER bodies that is involved in defense in Arabidopsis thaliana; and (iii) treatment of root cells with MeJA causes a significant increase in the number of ER bodies and the activity of β-glucosidases. More importantly, MeJA was found to induce the formation of very long ER bodies that results from the fusion of small ones, a phenomenon that has not been reported in any other study so far. These findings demonstrate that MeJA impacts the number and morphology of functional ER bodies and stimulates ER body enzyme activities, probably to participate in defense responses of radish root. They also suggest that these structures may provide a defensive system specific to root cells. PMID:25305245

  8. [Effects of human engineering activities on permafrost active layer and its environment in northern Qinghai-Tibetan plateau].

    PubMed

    Guo, Zhenggang; Wu, Qingbo; Niu, Fujun

    2006-11-01

    With disturbed and undisturbed belts during the construction of Qinghai-Tibet highway as test objectives, this paper studied the effects of human engineering activities on the permafrost ecosystem in northern Qinghai-Tibetan plateau. The results showed that the thickness of permafrost active layer was smaller in disturbed than in undisturbed belt, and decreased with increasing altitude in undisturbed belt while no definite pattern was observed in disturbed belt. Different vegetation types had different effects on the thickness of permafrost active layer, being decreased in the order of steppe > shrub > meadow. In the two belts, altitude was the main factor affecting the vertical distribution of soil moisture, but vegetation type was also an important affecting factor if the altitude was similar. Due to the human engineering activities, soil temperature in summer was lower in disturbed than in undisturbed belt.

  9. Diversity of aerobic methanotrophic bacteria in a permafrost active layer soil of the Lena Delta, Siberia.

    PubMed

    Liebner, Susanne; Rublack, Katja; Stuehrmann, Torben; Wagner, Dirk

    2009-01-01

    With this study, we present first data on the diversity of aerobic methanotrophic bacteria (MOB) in an Arctic permafrost active layer soil of the Lena Delta, Siberia. Applying denaturing gradient gel electrophoresis and cloning of 16S ribosomal ribonucleic acid (rRNA) and pmoA gene fragments of active layer samples, we found a general restriction of the methanotrophic diversity to sequences closely related to the genera Methylobacter and Methylosarcina, both type I MOB. In contrast, we revealed a distinct species-level diversity. Based on phylogenetic analysis of the 16S rRNA gene, two new clusters of MOB specific for the permafrost active layer soil of this study were found. In total, 8 out of 13 operational taxonomic units detected belong to these clusters. Members of these clusters were closely related to Methylobacter psychrophilus and Methylobacter tundripaludum, both isolated from Arctic environments. A dominance of MOB closely related to M. psychrophilus and M. tundripaludum was confirmed by an additional pmoA gene analysis. We used diversity indices such as the Shannon diversity index or the Chao1 richness estimator in order to compare the MOB community near the surface and near the permafrost table. We determined a similar diversity of the MOB community in both depths and suggest that it is not influenced by the extreme physical and geochemical gradients in the active layer. PMID:18592300

  10. Active Layer and Moisture Measurements for Intensive Site 0 and 1, Barrow, Alaska

    DOE Data Explorer

    John Peterson

    2015-04-17

    These are measurements of Active Layer Thickness collected along several lines beginning in September, 2011 to the present. The data were collected at several time periods along the Site0 L2 Line, the Site1 AB Line, and an ERT Monitoring Line near Area A in Site1.

  11. Extending the Diffuse Layer Model of Surface Acidity Behavior: III. Estimating Bound Site Activity Coefficients

    EPA Science Inventory

    Although detailed thermodynamic analyses of the 2-pK diffuse layer surface complexation model generally specify bound site activity coefficients for the purpose of accounting for those non-ideal excess free energies contributing to bound site electrochemical potentials, in applic...

  12. Groundwater hydrochemistry in the active layer of the proglacial zone, Finsterwalderbreen, Svalbard

    USGS Publications Warehouse

    Cooper, R.J.; Wadham, J.L.; Tranter, M.; Hodgkins, R.; Peters, N.E.

    2002-01-01

    Glacial bulk meltwaters and active-layer groundwaters were sampled from the proglacial zone of Finsterwalderbreen during a single melt season in 1999, in order to determine the geochemical processes that maintain high chemical weathering rates in the proglacial zone of this glacier. Results demonstrate that the principle means of solute acquisition is the weathering of highly reactive moraine and fluvial active-layer sediments by supra-permafrost groundwaters. Active-layer groundwater derives from the thaw of the proglacial snowpack, buried ice and glacial bulk meltwaters. Groundwater evolves by sulphide oxidation and carbonate dissolution. Evaporation- and freeze-concentration of groundwater in summer and winter, respectively produce Mg-Ca-sulphate salts on the proglacial surface. Re-dissolution of these salts in early summer produces groundwaters that are supersaturated with respect to calcite. There is a pronounced spatial pattern to the geochemical evolution of groundwater. Close to the main proglacial channel, active layer sediments are flushed diurnally by bulk meltwaters. Here, Mg-Ca-sulphate deposits become exhausted in the early season and geochemical evolution proceeds by a combination of sulphide oxidation and carbonate dissolution. At greater distances from the channel, the dissolution of Mg-Ca-sulphate salts is a major influence and dilution by the bulk meltwaters is relatively minor. The influence of sulphate salt dissolution decreases during the sampling season, as these salts are exhausted and waters become increasingly routed by subsurface flowpaths. ?? 2002 Elsevier Science B.V. All rights reserved.

  13. Activation of ethylenediaminetetraacetic acid by a 940 nm diode laser for enhanced removal of smear layer.

    PubMed

    Lagemann, Manfred; George, Roy; Chai, Lei; Walsh, Laurence J

    2014-08-01

    Laser enhancement of ethylenediaminetetraacetic acid with cetrimide (EDTAC) has previously been shown to increase removal of smear layer, for middle-infrared erbium lasers. This study evaluated the efficiency of EDTAC activation using a near-infrared-pulsed 940 nm laser delivered by plain fibre tips into 15% EDTAC or 3% hydrogen peroxide. Root canals in 4 groups of 10 single roots were prepared using rotary files, with controls for the presence and absence of smear layer. After laser treatment (80 mJ pulse(-1) , 50 Hz, 6 cycles of 10 s), roots were split and the apical, middle and coronal thirds of the canal were examined using scanning electron microscopy, with the area of dentine tubules determined by a validated quantitative image analysis method. Lasing EDTAC considerably improved smear layer removal, while lasing into peroxide gave minimal smear layer removal. The laser protocol used was more effective for smear layer removal than the 'gold standard' protocol using EDTAC with sodium hypochlorite (NaOCl). In addition, lasers may also provide a benefit through photothermal disinfection. Further research is needed to optimise irrigant activation protocols using near-infrared diode lasers of other wavelengths.

  14. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes

    PubMed Central

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-01-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them. PMID:27561546

  15. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes

    NASA Astrophysics Data System (ADS)

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-08-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them.

  16. A Novel Surface Structure Consisting of Contact-active Antibacterial Upper-layer and Antifouling Sub-layer Derived from Gemini Quaternary Ammonium Salt Polyurethanes.

    PubMed

    He, Wei; Zhang, Yi; Li, Jiehua; Gao, Yunlong; Luo, Feng; Tan, Hong; Wang, Kunjie; Fu, Qiang

    2016-01-01

    Contact-active antibacterial surfaces play a vital role in preventing bacterial contamination of artificial surfaces. In the past, numerous researches have been focused on antibacterial surfaces comprising of antifouling upper-layer and antibacterial sub-layer. In this work, we demonstrate a reversed surface structure which integrate antibacterial upper-layer and antifouling sub-layer. These surfaces are prepared by simply casting gemini quaternary ammonium salt waterborne polyurethanes (GWPU) and their blends. Due to the high interfacial energy of gemini quaternary ammonium salt (GQAS), chain segments containing GQAS can accumulate at polymer/air interface to form an antibacterial upper-layer spontaneously during the film formation. Meanwhile, the soft segments composed of polyethylene glycol (PEG) formed the antifouling sub-layer. Our findings indicate that the combination of antibacterial upper-layer and antifouling sub-layer endow these surfaces strong, long-lasting antifouling and contact-active antibacterial properties, with a more than 99.99% killing efficiency against both gram-positive and gram-negative bacteria attached to them. PMID:27561546

  17. Influence of the nanofibrous morphology on the catalytic activity of NiO nanostructures: an effective impact toward methanol electrooxidation

    PubMed Central

    2013-01-01

    In this study, the influence of the morphology on the electrocatalytic activity of nickel oxide nanostructures toward methanol oxidation is investigated. Two nanostructures were utilized: nanoparticles and nanofibers. NiO nanofibers have been synthesized by using the electrospinning technique. Briefly, electrospun nanofiber mats composed of polyvinylpyrolidine and nickel acetate were calcined at 700°C for 1 h. Interestingly, compared to nanoparticles, the nanofibrous morphology strongly enhanced the electrocatalytic performance. The corresponding current densities for the NiO nanofibers and nanoparticles were 25 and 6 mA/cm2, respectively. Moreover, the optimum methanol concentration increased to 1 M in case of the nanofibrous morphology while it was 0.1 M for the NiO nanoparticles. Actually, the one-dimensional feature of the nanofibrous morphology facilitates electrons' motion which enhances the electrocatalytic activity. Overall, this study emphasizes the distinct positive impact of the nanofibrous morphology on the electrocatalytic activity which will open a new avenue for modification of the electrocatalysts. PMID:24074313

  18. Cross-language activation of morphological relatives in cognates: the role of orthographic overlap and task-related processing.

    PubMed

    Mulder, Kimberley; Dijkstra, Ton; Baayen, R Harald

    2015-01-01

    We considered the role of orthography and task-related processing mechanisms in the activation of morphologically related complex words during bilingual word processing. So far, it has only been shown that such morphologically related words (i.e., morphological family members) are activated through the semantic and morphological overlap they share with the target word. In this study, we investigated family size effects in Dutch-English identical cognates (e.g., tent in both languages), non-identical cognates (e.g., pil and pill, in English and Dutch, respectively), and non-cognates (e.g., chicken in English). Because of their cross-linguistic overlap in orthography, reading a cognate can result in activation of family members both languages. Cognates are therefore well-suited for studying mechanisms underlying bilingual activation of morphologically complex words. We investigated family size effects in an English lexical decision task and a Dutch-English language decision task, both performed by Dutch-English bilinguals. English lexical decision showed a facilitatory effect of English and Dutch family size on the processing of English-Dutch cognates relative to English non-cognates. These family size effects were not dependent on cognate type. In contrast, for language decision, in which a bilingual context is created, Dutch and English family size effects were inhibitory. Here, the combined family size of both languages turned out to better predict reaction time than the separate family size in Dutch or English. Moreover, the combined family size interacted with cognate type: the response to identical cognates was slowed by morphological family members in both languages. We conclude that (1) family size effects are sensitive to the task performed on the lexical items, and (2) depend on both semantic and formal aspects of bilingual word processing. We discuss various mechanisms that can explain the observed family size effects in a spreading activation framework.

  19. The activity of the Colima volcano and morphological changes in the summit between 2004 and 2013

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Camarena Garcia, M. A.

    2013-05-01

    Colima Volcano, located in the West of the Volcanic Mexican Belt (19° 30.696 N, 103° 37.026 W), has shown a new cycle of explosive activity beginning May 30 1999, and reaching its maximum in March-April of 2005 and January 2013. In the 2005 the explosive activity increased gradually, having the largest event on May 23, when a new dome was created. Hours later this dome was destroyed by a strong explosion, forming an ash column 5.6 km high with subsequent pyroclastic flows that reached a distance of 4.2 km flowing along the ravines of the South sector. On May 30 the most intense explosion in 1999 occurred, when the plume reached heights in excess of 4.4 km above the crater, and pyroclastic flows were created. On the same year in July two explosive events occurred of characteristics similar to those in May. These constant explosions caused continuous morphological changes in the summit, the most significant being the collapse of the North and South walls of the crater, in the first week of June of 2005, and the creation of a new crater in July. In 2006 the most significant explosive activity took place during April, May and July, when the eruptive columns reached heights of more than 1500 meters above the crater, occasionally forming small pyroclastic flows. In May of 2007 morphological changes were observed in the summit. Among them a crater explosion on the East side, a dome was formed on the West side, with 20 m in high and 50 m in diameter. Since the end of 2008 to December of 2012 the volcano remained calm, with a dome diameter of 220 m and height of 60 m, in January 2013 three explosions occurred, destroying the dome and throwing a volume of 1.5 million cubic meters. The eruptive column reached a height of 3000 above the crater. It reported light ashfall to the NE to 100 km away from the volcano. The explosive events continue to date, but they have diminished in size and intensity. This activity was similar to the one observed in 1902-1903 and reported by

  20. Wild Sicilian rosemary: phytochemical and morphological screening and antioxidant activity evaluation of extracts and essential oils.

    PubMed

    Napoli, Edoardo M; Siracusa, Laura; Saija, Antonella; Speciale, Antonio; Trombetta, Domenico; Tuttolomondo, Teresa; La Bella, Salvatore; Licata, Mario; Virga, Giuseppe; Leone, Raffaele; Leto, Claudio; Rubino, Laura; Ruberto, Giuseppe

    2015-07-01

    To identify the best biotypes, an extensive survey of Sicilian wild rosemary was carried out by collecting 57 samples from various sites, followed by taxonomic characterization from an agronomic perspective. All the biotypes collected were classified as Rosmarinus officinalis L. A cluster analysis based on the morphological characteristics of the plants allowed the division of the biotypes into seven main groups, although the characteristics examined were found to be highly similar and not area-dependent. Moreover, all samples were analyzed for their phytochemical content, applying an extraction protocol to obtain the nonvolatile components and hydrodistillation to collect the essential oils for the volatile components. The extracts were characterized by LC-UV-DAD/ESI-MS, and the essential oils by GC-FID and GC/MS analyses. In the nonvolatile fractions, 18 components were identified, namely, 13 flavones, two organic acids, and three diterpenes. In the volatile fractions, a total of 82 components were found, with as predominant components α-pinene and camphene among the monoterpene hydrocarbons and 1,8-cineole, camphor, borneol, and verbenone among the oxygenated monoterpenes. Cluster analyses were carried out on both phytochemical profiles, allowing the separation of the rosemary samples into different chemical groups. Finally, the total phenol content and the antioxidant activity of the essential oils and extracts were determined with the Folin-Ciocalteu (FC) colorimetric assay, the UV radiation-induced peroxidation in liposomal membranes (UV-IP test), and the scavenging activity of the superoxide radical (O$\\rm{{_{2}^{{^\\cdot} -}}}$). The present study confirmed that the essential oils and organic extracts of the Sicilian rosemary samples analyzed showed a considerable antioxidant/free radical-scavenging activity.

  1. GBF-dependent family genes morphologically suppress the partially active Dictyostelium STATa strain.

    PubMed

    Shimada, Nao; Kanno-Tanabe, Naoko; Minemura, Kakeru; Kawata, Takefumi

    2008-02-01

    Transcription factor Dd-STATa, a functional Dictyostelium homologue of metazoan signal transducers and activators of transcription proteins, is necessary for culmination during development. We have isolated more than 18 putative multicopy suppressors of Dd-STATa using genetic screening. One was hssA gene, whose expression is known to be G-box-binding-factor-dependent and which was specific to prestalk A (pstA) cells, where Dd-STATa is activated. Also, hssA mRNA was expressed in pstA cells in the Dd-STATa-null mutant. At least 40 hssA-related genes are present in the genome and constitute a multigene family. The tagged HssA protein was translated; hssA encodes an unusually high-glycine-serine-rich small protein (8.37 kDa), which has strong homology to previously reported cyclic-adenosine-monophosphate-inducible 2C and 7E proteins. Overexpression of hssA mRNA as well as frame-shifted versions of hssA RNA suppressed the phenotype of the partially active Dd-STATa strain, suggesting that translation is not necessary for suppression. Although overexpression of prespore-specific genes among the family did not suppress the parental phenotype, prestalk-specific family members did. Although overexpression of the hssA did not revert the expression of Dd-STATa target genes, and although its suppression mechanism remains unknown, morphological reversion implies functional relationships between Dd-STATa and hssA.

  2. Electrical and mechanical characterization of nanoscale-layered cellulose-based electro-active paper.

    PubMed

    Yun, Gyu-Young; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

    2011-01-01

    In order to understand the electro-mechanical behavior of piezoelectric electro active paper (EAPap), the converse and direct piezoelectric characterization of cellulose EAPap was studied and compared. A delay between the electrical field and the induced strain of EAPap was observed due to the inner nano-voids or the localized amorphous regions in layer-by-layered structure to capture or hold the electrical charges and remnant ions. The linear relation between electric field and induced strain is also observed. The electro-mechanical performance of EAPap is discussed in detail in this paper.

  3. Thermal regime of active layer at two lithologically contrasting sites on James Ross Island, Antarctic Peninsula.

    NASA Astrophysics Data System (ADS)

    Hrbáček, Filip; Nývlt, Daniel; Láska, Kamil

    2016-04-01

    Antarctic Peninsula region (AP) represents one of the most rapidly warming parts of our planet in the last 50 years. Despite increasing research activities along both western and eastern sides of AP in last decades, there is still a lot of gaps in our knowledge relating to permafrost, active layer and its thermal and physical properties. This study brings new results of active layer monitoring on James Ross Island, which is the largest island in northern AP. Its northern part, Ulu Peninsula, is the largest ice-free area (more than 200 km2) in the region. Due its large area, we focused this study on sites located in different lithologies, which would affect local thermal regime of active layer. Study site (1) at Abernethy Flats area (41 m a.s.l.) lies ~7 km from northern coast. Lithologically is formed by disintegrated Cretaceous calcareous sandstones and siltstones of the Santa Marta Formation. Study site (2) is located at the northern slopes of Berry Hill (56 m a.s.l.), about 0.4 km from northern coastline. Lithology is composed of muddy to intermediate diamictites, tuffaceous siltstones to fine grained sandstones of the Mendel Formation. Data of air temperature at 2 meters above ground and the active layer temperatures at 75 cm deep profiles were obtained from both sites in period 1 January 2012 to 31 December 2014. Small differences were found when comparing mean air temperatures and active temperatures at 5 and 75 cm depth in the period 2012-2014. While the mean air temperatures varied between -7.7 °C and -7.0 °C, the mean ground temperatures fluctuated between -6.6 °C and -6.1 °C at 5 cm and -6.9 °C and -6.0 °C at 75 cm at Abernethy Flats and Berry Hill slopes respectively. Even though ground temperature differences along the profiles weren't pronounced during thawing seasons, the maximum active layer thickness was significantly larger at Berry Hill slopes (80 to 82 cm) than at Abernethy Flats (52 to 64 cm). We assume this differences are affected by

  4. Heterostructured Au/Pd-M (M = Au, Pd, Pt) nanoparticles with compartmentalized composition, morphology, and electrocatalytic activity.

    PubMed

    Lutz, Patrick S; Bae, In-Tae; Maye, Mathew M

    2015-10-14

    The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had high activity attributed to the porous nature of the platinum domains. PMID:26351824

  5. Photocatalytic activity of porous multiwalled carbon nanotube-TiO2 composite layers for pollutant degradation.

    PubMed

    Zouzelka, Radek; Kusumawati, Yuly; Remzova, Monika; Rathousky, Jiri; Pauporté, Thierry

    2016-11-01

    TiO2 nanoparticles are suitable building blocks nanostructures for the synthesis of porous functional thin films. Here we report the preparation of films using brookite, P25 titania and anatase pristine nanoparticles and of nanocomposite layers combining anatase nanoparticles and multi-walled carbon nanotube (MWCNT) at various concentrations. The structure and phase composition of the layers were characterized by X-ray diffraction and Raman spectroscopy. Their morphology and texture properties were determined by scanning electron microscopy and krypton adsorption experiments, respectively. Additionally to a strong absorption in the UV range, the composites exhibited light absorption in the visible range as well. The photocatalytic performance of the layers was tested in the degradation of aqueous solutions of 4-chlorophenol serving as a model of an eco-persistent pollutant. Besides the determination of the decrease in the concentration of 4-chlorophenol, also the formation of intermediate degradation products, namely hydroquinone and benzoquinone, was followed. The presence of MWCNTs had a beneficial effect on the photocatalytic performance, a marked increase in the photocatalytic degradation rate constant being observed even at very low concentrations of MWCNTs. Compared to a P25 reference layer, the first order rate reaction constant increased by about 100% for the composite films containing MWCNTs at concentrations above 0.6 wt%. The key parameters for the enhancement of the photocatalytic performance are discussed. The presence of carbon nanotubes influences beneficially the degradation of 4-chlorophenol by an attack of the primarily photoproduced hydroxyl radicals onto the 4-chlorophenol molecules. The degradation due to the direct charge transfer is practically not influenced at all.

  6. Photocatalytic activity of porous multiwalled carbon nanotube-TiO2 composite layers for pollutant degradation.

    PubMed

    Zouzelka, Radek; Kusumawati, Yuly; Remzova, Monika; Rathousky, Jiri; Pauporté, Thierry

    2016-11-01

    TiO2 nanoparticles are suitable building blocks nanostructures for the synthesis of porous functional thin films. Here we report the preparation of films using brookite, P25 titania and anatase pristine nanoparticles and of nanocomposite layers combining anatase nanoparticles and multi-walled carbon nanotube (MWCNT) at various concentrations. The structure and phase composition of the layers were characterized by X-ray diffraction and Raman spectroscopy. Their morphology and texture properties were determined by scanning electron microscopy and krypton adsorption experiments, respectively. Additionally to a strong absorption in the UV range, the composites exhibited light absorption in the visible range as well. The photocatalytic performance of the layers was tested in the degradation of aqueous solutions of 4-chlorophenol serving as a model of an eco-persistent pollutant. Besides the determination of the decrease in the concentration of 4-chlorophenol, also the formation of intermediate degradation products, namely hydroquinone and benzoquinone, was followed. The presence of MWCNTs had a beneficial effect on the photocatalytic performance, a marked increase in the photocatalytic degradation rate constant being observed even at very low concentrations of MWCNTs. Compared to a P25 reference layer, the first order rate reaction constant increased by about 100% for the composite films containing MWCNTs at concentrations above 0.6 wt%. The key parameters for the enhancement of the photocatalytic performance are discussed. The presence of carbon nanotubes influences beneficially the degradation of 4-chlorophenol by an attack of the primarily photoproduced hydroxyl radicals onto the 4-chlorophenol molecules. The degradation due to the direct charge transfer is practically not influenced at all. PMID:27262272

  7. New metal based drugs: spectral, electrochemical, DNA-binding, surface morphology and anticancer activity properties.

    PubMed

    Çeşme, Mustafa; Gölcü, Aysegul; Demirtaş, Ibrahim

    2015-01-25

    The NSAID piroxicam (PRX) drug was used for complex formation reactions with Cu(II), Zn(II) and Pt(II) metal salts have been synthesized. Then, these complexes have been characterized by spectroscopic and analytical techniques. Thermal behavior of the complexes were also investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to fish sperm double strand DNA (FSFSdsDNA) with UV spectroscopy. UV studies of the interaction of the PRX and its complexes with FSdsDNA have shown that these compounds can bind to FSdsDNA. The binding constants of the compounds with FSdsDNA have also been calculated. The morphology of the FSdsDNA, PRX, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with FSdsDNA has been studied by means of differential pulse voltammetry (DPV) at FSdsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism. The effect of proliferation PRX and complexes were examined on the HeLA and C6 cells using real-time cell analyzer with four different concentrations.

  8. New metal based drugs: Spectral, electrochemical, DNA-binding, surface morphology and anticancer activity properties

    NASA Astrophysics Data System (ADS)

    Çeşme, Mustafa; Gölcü, Aysegul; Demirtaş, Ibrahim

    2015-01-01

    The NSAID piroxicam (PRX) drug was used for complex formation reactions with Cu(II), Zn(II) and Pt(II) metal salts have been synthesized. Then, these complexes have been characterized by spectroscopic and analytical techniques. Thermal behavior of the complexes were also investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to fish sperm double strand DNA (FSFSdsDNA) with UV spectroscopy. UV studies of the interaction of the PRX and its complexes with FSdsDNA have shown that these compounds can bind to FSdsDNA. The binding constants of the compounds with FSdsDNA have also been calculated. The morphology of the FSdsDNA, PRX, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with FSdsDNA has been studied by means of differential pulse voltammetry (DPV) at FSdsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism. The effect of proliferation PRX and complexes were examined on the HeLA and C6 cells using real-time cell analyzer with four different concentrations.

  9. Active layer temperature in two Cryosols from King George Island, Maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Michel, Roberto F. M.; Schaefer, Carlos Ernesto G. R.; Poelking, Everton L.; Simas, Felipe N. B.; Fernandes Filho, Elpidio I.; Bockheim, James G.

    2012-06-01

    This study presents soil temperature and moisture regimes from March 2008 to January 2009 for two active layer monitoring (CALM-S) sites at King George Island, Maritime Antarctica. The monitoring sites were installed during the summer of 2008 and consist of thermistors (accuracy of ± 0.2 °C), arranged vertically with probes at different depths and one soil moisture probe placed at the bottommost layer at each site (accuracy of ± 2.5%), recording data at hourly intervals in a high capacity datalogger. The active layer thermal regime in the studied period for both soils was typical of periglacial environments, with extreme variation in surface temperature during summer resulting in frequent freeze and thaw cycles. The great majority of the soil temperature readings during the eleven month period was close to 0 °C, resulting in low values of freezing and thawing degree days. Both soils have poor thermal apparent diffusivity but values were higher for the soil from Fildes Peninsula. The different moisture regimes for the studied soils were attributed to soil texture, with the coarser soil presenting much lower water content during all seasons. Differences in water and ice contents may explain the contrasting patterns of freezing of the studied soils, being two-sided for the coarser soil and one-sided for the loamy soil. The temperature profile of the studied soils during the eleven month period indicates that the active layer reached a maximum depth of approximately 92 cm at Potter and 89 cm at Fildes. Longer data sets are needed for more conclusive analysis on active layer behaviour in this part of Antarctica.

  10. Influences and interactions of inundation, peat, and snow on active layer thickness

    NASA Astrophysics Data System (ADS)

    Atchley, Adam L.; Coon, Ethan T.; Painter, Scott L.; Harp, Dylan R.; Wilson, Cathy J.

    2016-05-01

    Active layer thickness (ALT), the uppermost layer of soil that thaws on an annual basis, is a direct control on the amount of organic carbon potentially available for decomposition and release to the atmosphere as carbon-rich Arctic permafrost soils thaw in a warming climate. We investigate how key site characteristics affect ALT using an integrated surface/subsurface permafrost thermal hydrology model. ALT is most sensitive to organic layer thickness followed by snow depth but is relatively insensitive to the amount of water on the landscape with other conditions held fixed. The weak ALT sensitivity to subsurface saturation suggests that changes in Arctic landscape hydrology may only have a minor effect on future ALT. However, surface inundation amplifies the sensitivities to the other parameters and under large snowpacks can trigger the formation of near-surface taliks.

  11. Influences and interactions of inundation, peat, and snow on active layer thickness

    DOE PAGES

    Atchley, Adam L.; Coon, Ethan T.; Painter, Scott L.; Harp, Dylan R.; Wilson, Cathy J.

    2016-05-18

    The effect of three environmental conditions: 1) thickness of organic soil, 2) snow depth, and 3) soil moisture content or water table height above and below the soil surface, on active layer thickness (ALT) are investigated using an ensemble of 1D thermal hydrology models. Sensitivity analyses of the ensemble exposed the isolated influence of each environmental condition on ALT and their multivariate interactions. The primary and interactive influences are illustrated in the form of color maps of ALT change. Results show that organic layer acts as a strong insulator, and its thickness is the dominant control of ALT, but themore » strength of the effect of organic layer thickness is dependent on the saturation state. Snow depth, subsurface saturation, and ponded water depth are strongly codependent and positively correlated to ALT.« less

  12. Realizing the full potential of Remotely Sensed Active Layer Thickness (ReSALT) Products

    NASA Astrophysics Data System (ADS)

    Schaefer, K. M.; Chen, A.; Liu, L.; Parsekian, A.; Jafarov, E. E.; Panda, S. K.; Zebker, H. A.

    2015-12-01

    The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence, active layer thickness (ALT), and thermokarst activity in permafrost regions. ReSALT supports research for the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential Nasa-Isro Synthetic Aperture Radar (NISAR) product. ALT is a critical parameter for monitoring the status of permafrost and thermokarst activity is one of the key drivers of change in permafrost regions. The ReSALT product currently includes 1) long-term subsidence trends resulting from the melting and subsequent drainage of excess ground ice in permafrost-affected soils, 2) seasonal subsidence resulting from the expansion of soil water into ice as the active layer freezes and thaws, and 3) ALT estimated from the seasonal subsidence assuming a vertical profile of water within the soil column. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. We present high resolution ReSALT products on the North Slope of Alaska: Prudhoe Bay, Barrow, Toolik Lake, Happy Valley, and the Anaktuvuk fire zone. We believe that the ReSALT product could be expanded to include maps of individual thermokarst features identified as spatial anomalies in the subsidence trends, with quantified expansion rates. We illustrate the technique with multiple examples of thermokarst features on the North Slope of Alaska. Knowing the locations and expansion rates for individual features allows us to evaluate risks to human infrastructure. Our results highlight the untapped potential of the InSAR technique to remotely sense ALT and thermokarst dynamics over large areas of the Arctic.

  13. A Scale-Adaptive Approach for Spatially-Varying Urban Morphology Characterization in Boundary Layer Parametrization Using Multi-Resolution Analysis

    NASA Astrophysics Data System (ADS)

    Mouzourides, P.; Kyprianou, A.; Neophytou, M. K.-A.

    2013-12-01

    Urban morphology characterization is crucial for the parametrization of boundary-layer development over urban areas. One complexity in such a characterization is the three-dimensional variation of the urban canopies and textures, which are customarily reduced to and represented by one-dimensional varying parametrization such as the aerodynamic roughness length and zero-plane displacement . The scope of the paper is to provide novel means for a scale-adaptive spatially-varying parametrization of the boundary layer by addressing this 3-D variation. Specifically, the 3-D variation of urban geometries often poses questions in the multi-scale modelling of air pollution dispersion and other climate or weather-related modelling applications that have not been addressed yet, such as: (a) how we represent urban attributes (parameters) appropriately for the multi-scale nature and multi-resolution basis of weather numerical models, (b) how we quantify the uniqueness of an urban database in the context of modelling urban effects in large-scale weather numerical models, and (c) how we derive the impact and influence of a particular building in pre-specified sub-domain areas of the urban database. We illustrate how multi-resolution analysis (MRA) addresses and answers the afore-mentioned questions by taking as an example the Central Business District of Oklahoma City. The selection of MRA is motivated by its capacity for multi-scale sampling; in the MRA the "urban" signal depicting a city is decomposed into an approximation, a representation at a higher scale, and a detail, the part removed at lower scales to yield the approximation. Different levels of approximations were deduced for the building height and planar packing density . A spatially-varying characterization with a scale-adaptive capacity is obtained for the boundary-layer parameters (aerodynamic roughness length and zero-plane displacement ) using the MRA-deduced results for the building height and the planar packing

  14. Premature Aging Phenotype in Mice Lacking High-Affinity Nicotinic Receptors: Region-Specific Changes in Layer V Pyramidal Cell Morphology.

    PubMed

    Konsolaki, Eleni; Skaliora, Irini

    2015-08-01

    The mechanisms by which aging leads to alterations in brain structure and cognitive deficits are unclear. Α deficient cholinergic system has been implicated as one of the main factors that could confer a heightened vulnerability to the aging process, and mice lacking high-affinity nicotinic receptors (β2(-/-)) have been proposed as an animal model of accelerated cognitive aging. To date, however, age-related changes in neuronal microanatomy have not been studied in these mice. In the present study, we examine the neuronal structure of yellow fluorescent protein (YFP(+)) layer V neurons in 2 cytoarchitectonically distinct cortical regions in wild-type (WT) and β2(-/-) animals. We find that (1) substantial morphological differences exist between YFP(+) cells of the anterior cingulate cortex (ACC) and primary visual cortex (V1), in both genotypes; (2) in WT animals, ACC cells are more susceptible to aging compared with cells in V1; and (3) β2 deletion is associated with a regionally and temporally specific increase in vulnerability to aging. ACC cells exhibit a prematurely aged phenotype already at 4-6 months, whereas V1 cells are spared in adulthood but strongly affected in old animals. Collectively, our data reveal region-specific synergistic effects of aging and genotype and suggest distinct vulnerabilities in V1 and ACC neurons.

  15. Crosslanguage Lexical Activation: A Test of the Revised Hierarchical and Morphological Decomposition Models in Arabic-English Bilinguals

    ERIC Educational Resources Information Center

    Qasem, Mousa; Foote, Rebecca

    2010-01-01

    This study tested the predictions of the revised hierarchical (RHM) and morphological decomposition (MDM) models with Arabic-English bilinguals. The RHM (Kroll & Stewart, 1994) predicts that the amount of activation of first language translation equivalents is negatively correlated with second language (L2) proficiency. The MDM (Frost, Forster, &…

  16. Activated carbon made from cow dung as electrode material for electrochemical double layer capacitor

    NASA Astrophysics Data System (ADS)

    Bhattacharjya, Dhrubajyoti; Yu, Jong-Sung

    2014-09-01

    Cow dung is one of the most abundant wastes generated on earth and has been traditionally used as fertilizer and fuel in most of the developing countries. In this study activated carbon is synthesized from cow dung by a modified chemical activation method, where partially carbonized cow dung is treated with KOH in different ratio. The synthesized activated carbon possesses irregular surface morphology with high surface area in the range of 1500-2000 m2 g-1 with proper amount of micropore and mesopore volume. In particular, we demonstrate that the surface morphology and porosity parameters change with increase in KOH ratio. These activated carbons are tested as electrode material in two-electrode symmetric supercapacitor system in non-aqueous electrolyte and found to exhibit high specific capacitance with excellent retention of it at high current density and for long term operation. In particular, the activated carbon synthesized at 2:1 ratio of KOH and the pre-carbonized char shows the best performance with specific capacitance of 124 F g-1 at 0.1 A g-1 and retains up to 117 F g-1 at 1.0 A g-1 current density. The performance is attributed to high surface area along with optimum amount of micropore and mesopore volume.

  17. Air-coupled piezoelectric transducers with active polypropylene foam matching layers.

    PubMed

    Gómez Alvarez-Arenas, Tomás E

    2013-05-10

    This work presents the design, construction and characterization of air-coupled piezoelectric transducers using 1-3 connectivity piezocomposite disks with a stack of matching layers being the outer one an active quarter wavelength layer made of polypropylene foam ferroelectret film. This kind of material has shown a stable piezoelectric response together with a very low acoustic impedance (<0.1 MRayl). These features make them a suitable candidate for the dual use or function proposed here: impedance matching layer and active material for air-coupled transduction. The transducer centre frequency is determined by the l/4 resonance of the polypropylene foam ferroelectret film (0.35 MHz), then, the rest of the transducer components (piezocomposite disk and passive intermediate matching layers) are all tuned to this frequency. The transducer has been tested in several working modes including pulse-echo and pitch-catch as well as wide and narrow band excitation. The performance of the proposed novel transducer is compared with that of a conventional air-coupled transducers operating in a similar frequency range.

  18. Activation of Extrasynaptic NMDARs at Individual Parallel Fiber–Molecular Layer Interneuron Synapses in Cerebellum

    PubMed Central

    Nahir, Ben

    2013-01-01

    NMDA receptors (NMDARs) expressed by cerebellar molecular layer interneurons (MLIs) are not activated by single exocytotic events but can respond to glutamate spillover following coactivation of adjacent parallel fibers (PFs), indicating that NMDARs are perisynaptic. Several types of synaptic plasticity rely on these receptors but whether they are activated at isolated synapses is not known. Using a combination of electrophysiological and optical recording techniques in acute slices of rat cerebellum, along with modeling, we find that repetitive activation of single PF–MLI synapses can activate NMDARs in MLIs. High-frequency stimulation, multivesicular release (MVR), or asynchronous release can each activate NMDARs. Frequency facilitation was found at all PF–MLI synapses but, while some showed robust MVR with increased release probability, most were limited to univesicular release. Together, these results reveal a functional diversity of PF synapses, which use different mechanisms to activate NMDARs. PMID:24107963

  19. Influence of the Halogen Activation on the Ozone Layer in XXIst Century

    NASA Astrophysics Data System (ADS)

    Larin, Igor; Aloyan, Artash; Yermakov, Alexandr

    2016-04-01

    The aim of the work is to evaluate a possible effect of heterophase chemical reactions (HCR) with participation of reservoir gases (ClONO2, HCl) and sulfate particles of the Junge layer on the ozone layer at mid-latitudes in the XXI century, which could be relevant for more accurate predicting a recovery of the ozone layer, taking into account that just these processes were the main cause of the ozone depletion at the end of XXth century. Required for calculating the dynamics of GHR data on the specific volume/surface of the sulfate aerosols in the lower stratosphere were taken from the data of field experiments. Their physico-chemical properties (chemical composition, density, water activity and free protons activity et al.) have been obtained with help of thermodynamic calculations (Atmospheric Inorganic Model, AIM). Altitude concentration profiles of individual gas components, as well as temperature and relative humidity (RH) at a given geographic location and season have been calculated using a two-dimensional model SOCRATES. The calculations have been made for the conditions of June 1995, 2040 and 2080 at 15 km altitude and 50° N latitude. It has been shown that the rate of ozone depletion as a result of processes involving halogen activation for the given conditions in 2040, 2080 is about 35% lower than a corresponding value in 1995 (a year of maximum effect of halogen activation). From this we can conclude that in the XXI century, despite the natural decline of ozone-depleting chlorofluorocarbons. processes of halogen activation of the ozone depletion with participation of sulfate aerosols should be taken into account in the calculations of the recovery of the ozone layer at mid-latitudes.

  20. Activity retention after nisin entrapment in a polyethylene oxide brush layer.

    PubMed

    Auxier, Julie A; Schilke, Karl F; McGuire, Joseph

    2014-09-01

    The cationic, amphiphilic peptide nisin is an effective inhibitor of gram-positive bacteria whose mode of action does not encourage pathogenic resistance, and its proper incorporation into food packaging could enhance food stability, safety, and quality in a number of circumstances. Sufficiently small peptides have been shown to integrate into otherwise nonfouling polyethylene oxide (PEO) brush layers in accordance with their amphiphilicity and ordered structure, including nisin, and we have recently shown that nisin entrapment within a PEO layer does not compromise the nonfouling character of that layer. In this work we test the hypothesis that surface-bound, pendant PEO chains will inhibit displacement of entrapped nisin by competing proteins and, in this way, prolong retention of nisin activity at the interface. For this purpose, the antimicrobial activity of nisinloaded, PEO-coated surfaces was evaluated against the gram-positive indicator strain, Pediococcus pentosaceous. The retained antimicrobial activity of nisin layers was evaluated on uncoated and PEO-coated surfaces after incubation in the presence of bovine serum albumin for contact periods up to 1 week. Nisin-loaded, uncoated and PEO-coated samples were withdrawn at selected times and were incubated on plates inoculated with P. pentosaceous to quantify nisin activity by determination of kill zone radii. Our results indicate that nisin activity is retained at a higher level for a longer period of time after entrapment within PEO than after direct adsorption in the absence of PEO, owing to inhibition of nisin exchange with dissolved protein afforded by the pendant PEO chains.

  1. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. III - NOAA active region 6233 (1990 August)

    NASA Technical Reports Server (NTRS)

    De La Beaujardiere, J.-F.; Canfield, Richard C.; Leka, K. D.

    1993-01-01

    We investigate the spatial relationship between vertical electric currents and flare phenomena in NOAA Active Region 6233, which was observed 1990, August 28-31 at Mees Solar Observatory. The two flares studied are the 1N/M1.8 flare on August 28, 22:30 UT and the 1N/M1.6 flare on August 29, 20:35 UT. Using Stokes polarimetry we make magnetograms of the region and compute the vertical current density. Using H-alpha imaging spectroscopy we identify sites of intense nonthermal electron precipitation or of high coronal pressure. The precipitation in these flares is barely strong enough to be detectable. We find that both precipitation and high pressure tend to occur near vertical currents, but that neither phenomenon is cospatial with current maxima. In contrast with the conclusion of other authors, we argue that these observations do not support a current-interruption model for flares, unless the relevant currents are primarily horizontal. The magnetic morphology and temporal evolution of these flares suggest that an erupting filament model may be relevant, but this model does not explicitly predict the relationship between precipitation, high pressure, and vertical currents.

  2. Phase- and morphology-controlled synthesis of cobalt sulfide nanocrystals and comparison of their catalytic activities for hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Pan, Yuan; Liu, Yunqi; Liu, Chenguang

    2015-12-01

    Colalt sulfide nanocrystals (NCs), including dandelion-like Co9S8 and sphere-like Co3S4, have been synthesized via a thermal decomposition approach using cobalt acetylacetonate as the cobalt source, 1-dodecanethiol as the sulfur source and oleic acid or oleylamine as the high boiling organic solvent. It is found that the molar ratio of the Co:S precursor and the species of solvent play an important role in the control of phase and morphology of cobalt sulfide nanostructures. The phase structure and morphology of the as-synthesized nickel sulfide NCs are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive spectrum (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption. Then we further compare the electrocatalytic activity and stability of as-synthesized cobalt sulfide NCs for hydrogen evolution reaction (HER). The results show that sphere-like Co3S4 exhibits better electrocatalytic activity than the dandelion-like Co9S8 NCs for HER, which can be attributed to the difference of phase structure and morphology. The sphere-like Co3S4 NCs have large surface area and high electrical conductivity, both are beneficial to enhance the catalytic activity. This study indicates that the crystalline phase structure and morphology of cobalt sulfide NCs are important for designing HER electrocatalysts with high efficiency and good stability.

  3. Active layer hydrology for Imnavait Creek, Toolik, Alaska. Annual progress report, July 1984--January 1986

    SciTech Connect

    Kane, D.L.

    1986-12-31

    In the annual hydrologic cycle, snowmelt is the most significant event at Imnavait Creek located near Toolik Lake, Alaska. Precipitation that has accumulated for more than 6 months on the surface melts in a relatively short period of 7 to 10 days once sustained melting occurs. During the ablation period, runoff dominates the hydrologic cycle. Some meltwater goes to rewetting the organic soils in the active layer. The remainder is lost primarily because of evaporation, since transpiration is not a very active process at this time. Following the snowmelt period, evapotranspiration becomes the dominate process, with base flow contributing the other watershed losses. It is important to note that the water initally lost by evapotranspiration entered the organic layer during melt. This water from the snowpack ensures that each year the various plant communities will have sufficient water to start a new summer of growth.

  4. Microtopographic and depth controls on active layer chemistry in Arctic polygonal ground

    SciTech Connect

    Newman, Brent D.; Throckmorton, Heather M.; Graham, David E.; Gu, Baohua; Hubbard, Susan S.; Liang, Liyuan; Wu, Yuxin; Heikoop, J. M.; Herndon, Elizabeth M.; Phelps, Tommy J.; Wilson, Cathy; Wullschleger, Stan D.

    2015-03-24

    Polygonal ground is a signature characteristic of Arctic lowlands, and carbon release from permafrost thaw can alter feedbacks to Arctic ecosystems and climate. This study describes the first comprehensive spatial examination of active layer biogeochemistry that extends across high- and low-centered, ice wedge polygons, their features, and with depth. Water chemistry measurements of 54 analytes were made on surface and active layer pore waters collected near Barrow, Alaska, USA. Significant differences were observed between high- and low-centered polygons suggesting that polygon types may be useful for landscape-scale geochemical classification. However, differences were found for polygon features (centers and troughs) for analytes that were not significant for polygon type, suggesting that finer-scale features affect biogeochemistry differently from polygon types. Depth variations were also significant, demonstrating important multidimensional aspects of polygonal ground biogeochemistry. These results have major implications for understanding how polygonal ground ecosystems function, and how they may respond to future change.

  5. Dual Gate Thin Film Transistors Based on Indium Oxide Active Layers

    SciTech Connect

    Kekuda, Dhananjaya; Rao, K. Mohan; Tolpadi, Amita; Chu, C. W.

    2011-07-15

    Polycrystalline Indium Oxide (In{sub 2}O{sub 3}) thin films were employed as an active channel layer for the fabrication of bottom and top gate thin film transistors. While conventional SiO{sub 2} served as a bottom gate dielectric, cross-linked poly-4-vinylphenol (PVP) was used a top gate dielectric. These nano-crystalline TFTs exhibited n-channel behavior with their transport behavior highly dependent on the thickness of the channel. The correlation between the thickness of the active layer and TFT parameters such as on/off ratio, field-effect mobility, threshold voltage were carried out. The optical spectra revealed a high transmittance in the entire visible region, thus making them promising candidates for the display technology.

  6. Microtopographic and depth controls on active layer chemistry in Arctic polygonal ground

    NASA Astrophysics Data System (ADS)

    Newman, B. D.; Throckmorton, H. M.; Graham, D. E.; Gu, B.; Hubbard, S. S.; Liang, L.; Wu, Y.; Heikoop, J. M.; Herndon, E. M.; Phelps, T. J.; Wilson, C. J.; Wullschleger, S. D.

    2015-03-01

    Polygonal ground is a signature characteristic of Arctic lowlands, and carbon release from permafrost thaw can alter feedbacks to Arctic ecosystems and climate. This study describes the first comprehensive spatial examination of active layer biogeochemistry that extends across high- and low-centered, ice wedge polygons, their features, and with depth. Water chemistry measurements of 54 analytes were made on surface and active layer pore waters collected near Barrow, Alaska, USA. Significant differences were observed between high- and low-centered polygons suggesting that polygon types may be useful for landscape-scale geochemical classification. However, differences were found for polygon features (centers and troughs) for analytes that were not significant for polygon type, suggesting that finer-scale features affect biogeochemistry differently from polygon types. Depth variations were also significant, demonstrating important multidimensional aspects of polygonal ground biogeochemistry. These results have major implications for understanding how polygonal ground ecosystems function, and how they may respond to future change.

  7. Coma Morphology Due to an Extended Active Region and Implications for the Spin State of Comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Samarasinha, Nalin H.

    2000-01-01

    We show that the circular character of continuum structures observed in the coma of comet Hale-Bopp around the perihelion passage is most likely due to a dust jet from a large extended active region on the surface. Coma morphology due to a wide jet is different from that due to a narrow jet. The latter shows foreshortening effects due to observing geometry, wider jet produces more circular features. This circularization effect provides a self-consistent explanation for the evolution of near-perihelion coma morphology. No changes in the direction of the rotational angular momentum vector are required during this period in contrast to the models of Schleicher et al. This circularization effect also enables us to produce near-circular coma features in the S-E quadrant during 1997 late February and therefore questions the basic premise on which Sekanina bases his morphological arguments for a gravitationally bound satellite nucleus.

  8. The morphology of an active zone near Enceladus' south pole and implications

    NASA Astrophysics Data System (ADS)

    Giese, Bernd; Helfenstein, Paul; Thomas, Peter C.; Ingersoll, Andrew P.; Perry, Jason; Wagner, Roland; Neukum, Gerhard; Porco, Carolyn C.

    2010-05-01

    On Cassini's 121st orbit, the onboard ISS camera acquired high-resolution (15-30 m/pxl) images in Enceladus' south polar province. The imaging sequence was specifically designed to study one of the source regions of Enceladus' erupting plumes, Baghdad Sulcus. To facilitate the analysis, we derived a digital elevation model in an active section (76°S/323°E) across Baghdad Sulcus. The model reveals that there is a V-shaped trough up to 500 m deep in the center of this section, with flanking slopes of 30° (SW-facing) and > 32° (NE-facing, this slope is in shadow). The slopes do approach angle of repose, but the morphology on the SW slope (blocky terrain with lineation patterns and even benches at angles to the maximum slope) suggests that this is not a slope undergoing angle-of-repose control. The trough, therefore, may owe its shape primarily to faulting, with only some modification by deposition of icy particles by the plume-forming gas. Blocky covering, which includes block sizes of up to 50 m, is not restricted to the trough but also occurs at about the same size and frequency distribution away from it. This suggests that the blocks are not related to the venting process, which concentrates in the trough. Rather, the association of the blocky surfaces with multiple patterns of lineations (presumably fractures and faults) suggests they are outcrops of fault-related ice blocks or lithified detritus undergoing some form of erosion. A potential erosion process may include seismic shaking. The V-shaped trough is partly accompanied by an elevated flanking ridge, which is indicative for rift zones and hints at an extensional origin of Baghdad Sulcus. Alternatively, fault-block rotation at large strains could have led to the elevated ridge.

  9. Modulation of Hepatocarcinoma Cell Morphology and Activity by Parylene-C Coating on PDMS

    PubMed Central

    Guimard, Denis; Arakawa, Yasuhiko; Sakai, Yasuyuki; Fujii, Teruo

    2010-01-01

    Background The ability to understand and locally control the morphogenesis of mammalian cells is a fundamental objective of cell and developmental biology as well as tissue engineering research. We present parylene-C (ParC) deposited on polydimethylsiloxane (PDMS) as a new substratum for in vitro advanced cell culture in the case of Human Hepatocarcinoma (HepG2) cells. Principal Findings Our findings establish that the intrinsic properties of ParC-coated PDMS (ParC/PDMS) influence and modulate initial extracellular matrix (ECM; here, type-I collagen) surface architecture, as compared to non-coated PDMS substratum. Morphological changes induced by the presence of ParC on PDMS were shown to directly affect liver cell metabolic activity and the expression of transmembrane receptors implicated in cell adhesion and cell-cell interaction. These changes were characterized by atomic force microscopy (AFM), which elucidated differences in HepG2 cell adhesion, spreading, and reorganization into two- or three-dimensional structures by neosynthesis of ECM components. Local modulation of cell aggregation was successfully performed using ParC/PDMS micropatterns constructed by simple microfabrication. Conclusion/Significance We demonstrated for the first time the modulation of HepG2 cells' behavior in relation to the intrinsic physical properties of PDMS and ParC, enabling the local modulation of cell spreading in a 2D or 3D manner by simple microfabrication techniques. This work will provide promising insights into the development of cell-based platforms that have many applications in the field of in vitro liver tissue engineering, pharmacology and therapeutics. PMID:20300511

  10. Mechanisms for quenching star formation activities in green valley galaxies and its depends on morphologies

    NASA Astrophysics Data System (ADS)

    Kong, Xu; Pan, Zhizheng; Lian, Jianhui

    2015-08-01

    Galaxies are categorized into two main populations, red quiescent galaxies and blue star-forming galaxies. One of the key questions is which physical mechanisms are responsible for quenching star formation activities in blue galaxies and the resulting transformation? In this talk, we present research on the morphologies, spectra, and environments of "green valley" galaxies in the COSMOS field and low redshift "green valley" galaxies in SDSS. Our findings suggest that environmental conditions, most likely starvation and harassment, significantly affect the transformation of M* < 10^10.0 Msun blue galaxies into red galaxies, especially at z < 0.5. Using image from SDSS and GALEX, we analyze the radial ultraviolet-optical color distributions in a sample of low redshift green valley galaxies, and investigate how quenching is processing in a galaxy. The early-type "green valley" galaxies (ETGs) have dramatically different radial NUV-r color distributions compared to late-type "green valley" galaxies (LTGs), most of ETGs have blue cores, nearly all LTGs have uniform color profiles that can be well-interpreted as red bulges plus blue disk components. These results suggest that the LTGs follow a general model by which quenching first occurs in the core regions, and then finally extend to the rest of the galaxy; for ETGs, their star formations are centrally concentrated. Our results can be re-examined and have important implications for the IFU surveys, such as MaNGA and SAMI (2013ApJ...776...14P, 2014ApJ...792L...4P, 2015MNRAS.446.1449L).

  11. Changes in lysosomal morphology and enzyme activities during the development of adriamycin-induced cardiomyopathy.

    PubMed

    Singal, P K; Segstro, R J; Singh, R P; Kutryk, M J

    1985-03-01

    Morphologic and enzymic changes in heart lysosomes were studied following a chronic treatment of animals with a cumulative dose of 15 mg/kg of adriamycin. Myocardial cell damage due to adriamycin included lysosomal changes, sarcotubular swelling, vacuolization and myofibrillar drop-out. These structural changes were more pronounced in the 6-week treated group as opposed to the 3-week treated group. The number of lysosomes per unit area increased from a control value of 3.6 +/- 1.7 to 17.8 +/- 4.0 in the 3-week treated group and 35.9 +/- 9.2 in the 6-week treated groups, respectively. The scatter in the size distribution of lysosomes was much wider in treated animals. Lysosomal hydrolases in the 3-week and 6-week adriamycin-treated group changed as follows: N acetyl beta-glucosaminidase activity fell in the homogenate (H) and nonsedimentable (NS) and rose in the serum (Ser) fractions; a drop in alpha-mannosidase was seen in the sedimentable (S) and Ser fractions; an increase in beta-galactosidase was noted in the H, S and Ser fractions; acid phosphatase was increased in H, S, NS and Ser fractions. Lanthanum staining, used as a cytochemical probe for normal membrane permeability, revealed intracytoplasmic localization of the tracer only in the 6-week group. Malondialdehyde content was increased significantly in the 3-week and 6-weed treated groups. These results show lysosomal changes in adriamycin-treated hearts which precede as well as accompany nonspecific permeability changes in the sarcolemma.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3931886

  12. Fluvial morphology of Naktong Vallis, Mars: A late activity with multiple processes

    NASA Astrophysics Data System (ADS)

    Bouley, S.; Ansan, V.; Mangold, N.; Masson, Ph.; Neukum, G.

    2009-07-01

    The morphology of fluvial valleys on Mars provides insight into surface and subsurface hydrology, as well as to Mars' past climate. In this study, Naktong Vallis and its tributaries were examined from high-resolution stereoscopic camera (HRSC) images, thermal emission imaging system (THEMIS) daytime IR images, and mars orbiter laser altimeter (MOLA) data. Naktong Vallis is the southern part of a very large fluvial basin composed by Mamers, Scamander, and Naktong Vallis with a total length of 4700 km, and is one of the largest fluvial system on Mars. Naktong Vallis incised along its path a series of smooth intercrater plains. Naktong's main valley cut smooth plains during the Early Hesperian period, estimated ˜3.6-3.7 Gyr, implying a young age for the valley when compared to usual Noachian-aged valley networks. Branching valleys located in degraded terrains south of the main Naktong valley have sources inside a large plateau located at more than 2000 m elevation. Connections between these valleys and Naktong Vallis have been erased by the superimposition of late intercrater plains of Early to Late Hesperian age, but it is likely that this plateau represents the main source of water. Small re-incisions of these late plains show that there was at least one local reactivation. In addition, valley heads are often amphitheatre-shaped. Despite the possibility of subsurface flows, the occurrence of many branching valleys upstream of Naktong's main valley indicate that runoff may have played an important role in Naktong Vallis network formation. The importance of erosional landforms in the Naktong Vallis network indicates that fluvial activity was important and not necessarily lower in the Early Hesperian epoch than during the Noachian period. The relationships between overland flows and sapping features suggest a strong link between the two processes, rather than a progressive shift from surface to subsurface flow.

  13. A Comparison of Active and Passive Methods for Control of Hypersonic Boundary Layers on Airbreathing Configurations

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Nowak, Robert J.

    2003-01-01

    Active and passive methods for control of hypersonic boundary layers have been experimentally examined in NASA Langley Research Center wind tunnels on a Hyper-X model. Several configurations for forcing transition using passive discrete roughness elements and active mass addition, or blowing, methods were compared in two hypersonic facilities, the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air tunnels. Heat transfer distributions, obtained via phosphor thermography, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. The comparisons between the active and passive methods for boundary layer control were conducted at test conditions that nearly match the nominal Mach 7 flight trajectory of an angle-of-attack of 2-deg and length Reynolds number of 5.6 million. For the passive roughness examination, the primary parametric variation was a range of trip heights within the calculated boundary layer thickness for several trip concepts. The prior passive roughness study resulted in a swept ramp configuration being selected for the Mach 7 flight vehicle that was scaled to be roughly 0.6 of the calculated boundary layer thickness. For the active jet blowing study, the blowing manifold pressure was systematically varied for each configuration, while monitoring the mass flow, to determine the jet penetration height with schlieren and transition movement with the phosphor system for comparison to the passive results. All the blowing concepts tested were adequate for providing transition onset near the trip location with manifold stagnation pressures on the order of 40 times the model static pressure or higher.

  14. Acoustic radiation from the submerged circular cylindrical shell treated with active constrained layer damping

    NASA Astrophysics Data System (ADS)

    Yuan, Li-Yun; Xiang, Yu; Lu, Jing; Jiang, Hong-Hua

    2015-12-01

    Based on the transfer matrix method of exploring the circular cylindrical shell treated with active constrained layer damping (i.e., ACLD), combined with the analytical solution of the Helmholtz equation for a point source, a multi-point multipole virtual source simulation method is for the first time proposed for solving the acoustic radiation problem of a submerged ACLD shell. This approach, wherein some virtual point sources are assumed to be evenly distributed on the axial line of the cylindrical shell, and the sound pressure could be written in the form of the sum of the wave functions series with the undetermined coefficients, is demonstrated to be accurate to achieve the radiation acoustic pressure of the pulsating and oscillating spheres respectively. Meanwhile, this approach is proved to be accurate to obtain the radiation acoustic pressure for a stiffened cylindrical shell. Then, the chosen number of the virtual distributed point sources and truncated number of the wave functions series are discussed to achieve the approximate radiation acoustic pressure of an ACLD cylindrical shell. Applying this method, different radiation acoustic pressures of a submerged ACLD cylindrical shell with different boundary conditions, different thickness values of viscoelastic and piezoelectric layer, different feedback gains for the piezoelectric layer and coverage of ACLD are discussed in detail. Results show that a thicker thickness and larger velocity gain for the piezoelectric layer and larger coverage of the ACLD layer can obtain a better damping effect for the whole structure in general. Whereas, laying a thicker viscoelastic layer is not always a better treatment to achieve a better acoustic characteristic. Project supported by the National Natural Science Foundation of China (Grant Nos. 11162001, 11502056, and 51105083), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2012GXNSFAA053207), the Doctor Foundation of Guangxi

  15. Origin of photogenerated carrier recombination at the metal-active layer interface in polymer solar cells.

    PubMed

    Kumar, Mukesh; Dubey, Ashish; Reza, Khan Mamun; Adhikari, Nirmal; Qiao, Qiquan; Bommisetty, Venkat

    2015-11-01

    The role of the metal-active layer interface in photogenerated recombination has been investigated using nanoscale current sensing atomic force microscopy (CS-AFM) and intensity modulated photocurrent spectroscopy (IMPS) in as-deposited, pre-annealed and post-annealed bulk heterojunction (BHJ) solar cells. Aluminum (Al) confined post-annealed BHJ solar cells exhibited a significantly improved device efficiency compared to pre-annealed BHJ solar cells having similar photocarrier harvesting ability in the active layer. The nanoscale topography and CS-AFM results indicate a uniform PCBM rich phase at the metal-active layer interface in the post-annealed cells, but PCBM segregation in the pre-annealed cells. These two different annealing processes showed different carrier dynamics revealed using IMPS under various light intensities. The IMPS results suggest reduced photo generated carrier recombination in uniform PCBM rich post-annealed BHJ solar cells. This study reveals the importance of the metal-bend interface in BHJ solar cells in order to obtain efficient charge carrier extraction for high efficiency. PMID:26431263

  16. Architectural evolution of the Nojima fault and identification of the activated slip layer by Kobe earthquake

    NASA Astrophysics Data System (ADS)

    Tanaka, Hidemi; Omura, Kentaro; Matsuda, Tatsuo; Ikeda, Ryuji; Kobayashi, Kenta; Murakami, Masaki; Shimada, Koji

    2007-07-01

    Evolutionary history of Nojima Fault zone is clarified by comprehensive examinations of petrological, geophysical, and geochemical characterizations on a fault zone in deep-drilled core penetrating the Nojima Fault. On the basis of the results, we reconstruct a whole depth profile of the architecture of the Nojima Fault and identify the primal slip layer activated by 1995 Kobe earthquake. The deepest part (8- to 12-km depth) of the fault zone is composed of thin slip layers of pseudotachylite (5 to 10 mm thick each, 10 cm in total). Middle depth (4- to 8-km depth) of the fault zone is composed of fault core (6 to 10 m thick), surrounded by thick (100 m thick) damage zone, characterized by zeolite precipitation. The shallow part of the fault zone (1- to 4-km depth) is composed of distributed narrow shear zones, which are characterized by combination of thin (0.5 cm thick each, 10 cm in total) ultracataclasite layers at the core of shear zones, surrounded by thicker (1 to 3 m thick) damage zones associated with carbonate precipitation. An extremely thin ultracataclasite layer (7 mm thick), activated by the 1995 Kobe earthquake, is clearly identified from numerous past slip layers, overprinting one of the shear zones, as evidenced by conspicuous geological and geophysical anomalies. The Nojima Fault zone was 10 to 100 times thicker at middle depth than that of shallower and deeper depths. The thickening would be explained as a combination of physical and chemical effects as follows. (1) Thickening of "fault core" at middle depth would be attributed to normal stress dependence on thickness of the shear zone and (2) an extreme thickening of "damage zone" in middle depth of the crust would result from the weakening of the fault zone due to super hydrostatic fluid pressure at middle depths. The high fluid pressure would result from faster sealing with low-temperature carbonate at the shallower fault zone.

  17. Bioavailable Carbon and the Relative Degradation State of Organic Matter in Active Layer and Permafrost Soils

    NASA Astrophysics Data System (ADS)

    Jastrow, J. D.; Burke, V. J.; Vugteveen, T. W.; Fan, Z.; Hofmann, S. M.; Lederhouse, J. S.; Matamala, R.; Michaelson, G. J.; Mishra, U.; Ping, C. L.

    2015-12-01

    The decomposability of soil organic carbon (SOC) in permafrost regions is a key uncertainty in efforts to predict carbon release from thawing permafrost and its impacts. The cold and often wet environment is the dominant factor limiting decomposer activity, and soil organic matter is often preserved in a relatively undecomposed and uncomplexed state. Thus, the impacts of soil warming and permafrost thaw are likely to depend at least initially on the genesis and past history of organic matter degradation before its stabilization in permafrost. We compared the bioavailability and relative degradation state of SOC in active layer and permafrost soils from Arctic tundra in Alaska. To assess readily bioavailable SOC, we quantified salt (0.5 M K2SO4) extractable organic matter (SEOM), which correlates well with carbon mineralization rates in short-term soil incubations. To assess the relative degradation state of SOC, we used particle size fractionation to isolate fibric (coarse) from more degraded (fine) particulate organic matter (POM) and separated mineral-associated organic matter into silt- and clay-sized fractions. On average, bulk SOC concentrations in permafrost were lower than in comparable active layer horizons. Although SEOM represented a very small proportion of the bulk SOC, this proportion was greater in permafrost than in comparable active layer soils. A large proportion of bulk SOC was found in POM for all horizons. Even for mineral soils, about 40% of bulk SOC was in POM pools, indicating that organic matter in both active layer and permafrost mineral soils was relatively undecomposed compared to typical temperate soils. Not surprisingly, organic soils had a greater proportion of POM and mineral soils had greater silt- and clay-sized carbon pools, while cryoturbated soils were intermediate. For organic horizons, permafrost organic matter was generally more degraded than in comparable active layer horizons. However, in mineral and cryoturbated horizons

  18. Real-time monitoring of enzyme activity in a mesoporous silicon double layer

    NASA Astrophysics Data System (ADS)

    Orosco, Manuel M.; Pacholski, Claudia; Sailor, Michael J.

    2009-04-01

    The activity of certain proteolytic enzymes is often an indicator of disease states such as cancer, stroke and neurodegeneracy, so there is a need for rapid assays that can characterize the kinetics and substrate specificity of enzymatic reactions. Nanostructured membranes can efficiently separate biomolecules, but coupling a sensitive detection method to such a membrane remains difficult. Here, we demonstrate a single mesoporous nanoreactor that can isolate and quantify in real time the reaction products of proteases. The reactor consists of two layers of porous films electrochemically prepared from crystalline silicon. The upper layer, with large pore sizes (~100 nm in diameter), traps the protease and acts as the reactor. The lower layer, with smaller pore sizes (~6 nm), excludes the proteases and other large proteins and captures the reaction products. Infiltration of the digested fragments into the lower layer produces a measurable change in optical reflectivity, and this allows label-free quantification of enzyme kinetics in real time within a volume of ~5 nl.

  19. Electrical and morphological characterization of transfer-printed Au/Ti/TiOx/p+-Si nano- and microstructures with plasma-grown titanium oxide layers

    NASA Astrophysics Data System (ADS)

    Weiler, Benedikt; Nagel, Robin; Albes, Tim; Haeberle, Tobias; Gagliardi, Alessio; Lugli, Paolo

    2016-04-01

    Highly-ordered, sub-70 nm-MOS-junctions of Au/Ti/TiOx/p+-Si were efficiently and reliably fabricated by nanotransfer-printing (nTP) over large areas and their functionality was investigated with respect to their application as MOS-devices. First, we used a temperature-enhanced nTP process and integrated the plasma-oxidation of a nm-thin titanium film being e-beam evaporated directly on the stamp before the printing step without affecting the p+-Si substrate. Second, morphological investigations (scanning electron microscopy) of the nanostructures confirm the reliable transfer of Au/Ti/TiOx-pillars of 50 nm, 75 nm, and 100 nm size of superior quality on p+-Si by our transfer protocol. Third, the fabricated nanodevices are also characterized electrically by conductive AFM. Fourth, the results are compared to probe station measurements on identically processed, i.e., transfer-printed μm-MOS-structures including a systematic investigation of the oxide formation. The jV-characteristics of these MOS-junctions demonstrate the electrical functionality as plasma-grown tunneling oxides and the effectivity of the transfer-printing process for their large-scale fabrication. Next, our findings are supported by fits to the jV-curves of the plasma-grown titanium oxide by kinetic-Monte-Carlo simulations. These fits allowed us to determine the dominant conduction mechanisms, the material parameters of the oxides and, in particular, a calibration of the thickness depending on applied plasma time and power. Finally, also a relative dielectric permittivity of 12 was found for such plasma-grown TiOx-layers.

  20. Microbial activities at the benthic boundary layer in the Aegean Sea

    NASA Astrophysics Data System (ADS)

    Bianchi, A.; Tholosan, O.; Garcin, J.; Polychronaki, T.; Tselepides, A.; Buscail, R.; Duineveld, G.

    2003-05-01

    During the Aegean Sea component of the EU MTP-MATER project, benthic samples were acquired along a depth gradient from two continental margins in the Aegean Sea. Sampling was undertaken during spring and summer 1997 and the microbial metabolic activities measured (Vmax for aminopeptidase activity, 14C-glutamate respiration and assimilation) displayed seasonal variability even in deep-sea conditions. The metabolic rates encountered in the North Aegean (average depth 566±234 m), were approximately five-fold higher than in the deeper (1336±140 m) Southern part of the Aegean. The aminopeptidase rates, however, were the exception with higher values recorded in the more oligotrophic sediments of the Southern stations (1383±152 vs. 766±297 nmol MCA cm -2 h -1). A discrepancy in bacterial metabolism also appeared in the near bottom waters. In the Southern stations, 80% of the glutamate uptake was used for energy yielding processes and only 20% devoted to biomass production, while in the North Aegean, most of the used glutamate was incorporated into bacterial cells. During the early burial stages, bacterial mineralization rates estimated from 14C-glutamate respiration decreased drastically compared to the rates of biopolymer hydrolysis estimated by aminopeptidase assays. Thus, at the 2-cm depth layer, these rates were only 32 and up to 77% of the corresponding average values, respectively, in the superficial layer. Such a discrepancy between the evolution of these two metabolic activities is possibly due to the rapid removal of readily utilizable monomers in the surface deposits. The correlation between bacterial respiration and total organic carbon, or total organic nitrogen, is higher in the surficial sediment (0-2 and 2-4 cm) than in the underlying layer. Conversely, it is only at 4-cm depth layer that the hydrolysis rates appear correlated with organic carbon and nitrogen concentrations. This pattern confirms the drastic degradation of organic matter during the

  1. Active layer thermal regime at different vegetation covers at Lions Rump, King George Island, Maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Almeida, Ivan C. C.; Schaefer, Carlos Ernesto G. R.; Fernandes, Raphael B. A.; Pereira, Thiago T. C.; Nieuwendam, Alexandre; Pereira, Antônio Batista

    2014-11-01

    Climate change impacts the biotic and abiotic components of polar ecosystems, affecting the stability of permafrost, active layer thickness, vegetation, and soil. This paper describes the active layer thermal regimes of two adjacent shallow boreholes, under the same soil but with two different vegetations. The study is location in Lions Rump, at King George Island, Maritime Antarctic, one of the most sensitive regions to climate change, located near the climatic limit of Antarctic permafrost. Both sites are a Turbic Cambic Cryosol formed on andesitic basalt, one under moss vegetation (Andreaea gainii, at 85 m a.s.l.) and another under lichen (Usnea sp., at 86 m a.s.l.), located 10 m apart. Ground temperature at same depths (10, 30 and 80 cm), water content at 80 cm depth and air temperature were recorded hourly between March 2009 and February 2011. The two sites showed significant differences in mean annual ground temperature for all depths. The lichen site showed a higher soil temperature amplitude compared to the moss site, with ground surface (10 cm) showing the highest daily temperature in January 2011 (7.3 °C) and the lowest daily temperature in August (- 16.5 °C). The soil temperature at the lichen site closely followed the air temperature trend. The moss site showed a higher water content at the bottommost layer, consistent with the water-saturated, low landscape position. The observed thermal buffering effect under mosses is primarily associated with higher moisture onsite, but a longer duration of the snowpack (not monitored) may also have influenced the results. Active layer thickness was approximately 150 cm at low-lying moss site, and 120 cm at well-drained lichen site. This allows to classify these soils as Cryosols (WRB) or Gelisols (Soil Taxonomy), with evident turbic features.

  2. Active but inoperable thrombin is accumulated in a plasma protein layer surrounding Streptococcus pyogenes.

    PubMed

    Naudin, Clément; Hurley, Sinead M; Malmström, Erik; Plug, Tom; Shannon, Oonagh; Meijers, Joost C M; Mörgelin, Matthias; Björck, Lars; Herwald, Heiko

    2015-10-01

    Activation of thrombin is a critical determinant in many physiological and pathological processes including haemostasis and inflammation. Under physiological conditions many of these functions are involved in wound healing or eradication of an invading pathogen. However, when activated systemically, thrombin can contribute to severe and life-threatening conditions by causing complications such as multiple multi-organ failure and disseminated intravascular coagulation. In the present study we investigated how the activity of thrombin is modulated when it is bound to the surface of Streptococcus pyogenes. Our data show that S. pyogenes bacteria become covered with a proteinaceous layer when incubated with human plasma, and that thrombin is a constituent of this layer. Though the coagulation factor is found attached to the bacteria with a functional active site, thrombin has lost its capacity to interact with its natural substrates and inhibitors. Thus, the interaction of bacteria with human plasma renders thrombin completely inoperable at the streptococcal surface. This could represent a host defense mechanism to avoid systemic activation of coagulation which could be otherwise induced when bacteria enter the circulation and cause systemic infection.

  3. Superior Photostability and Photocatalytic Activity of ZnO Nanoparticles Coated with Ultrathin TiO2 Layers through Atomic-Layer Deposition.

    PubMed

    Sridharan, Kishore; Jang, Eunyong; Park, Young Min; Park, Tae Joo

    2015-12-21

    Atomic-layer deposition (ALD) is a thin-film growth technology that allows for conformal growth of thin films with atomic-level control over their thickness. Although ALD is successful in the semiconductor manufacturing industry, its feasibility for nanoparticle coating has been less explored. Herein, the ALD coating of TiO2 layers on ZnO nanoparticles by employing a specialized rotary reactor is demonstrated. The photocatalytic activity and photostability of ZnO nanoparticles coated with TiO2 layers by ALD and chemical methods were examined by the photodegradation of Rhodamine B dye under UV irradiation. Even though the photocatalytic activity of the presynthesized ZnO nanoparticles is higher than that of commercial P25 TiO2 nanoparticles, their activity tends to decline due to severe photocorrosion. The chemically synthesized TiO2 coating layer on ZnO resulted in severely declined photoactivity despite the improved photostability. However, ultrathin and conformal ALD TiO2 coatings (≈ 0.75-1.5 nm) on ZnO improved its photostability without degradation of photocatalytic activity. Surprisingly, the photostability is comparable to that of pure TiO2, and the photocatalytic activity to that of pure ZnO.

  4. Morphological changes of the filamentous fungus Mucor mucedo and inhibition of chitin synthase activity induced by anethole.

    PubMed

    Yutani, Masahiro; Hashimoto, Yukie; Ogita, Akira; Kubo, Isao; Tanaka, Toshio; Fujita, Ken-ichi

    2011-11-01

    trans-Anethole (anethole), a major component of anise oil, has a broad antimicrobial spectrum with antimicrobial activity relatively weaker than those of well-known antibiotics, and significantly enhances the antifungal activity of polygodial and dodecanol against the baker's yeast Saccharomyces cerevisiae and human pathogenic yeast Candida albicans. However, the antifungal mechanism of anethole is unresolved. Anethole demonstrated antifungal activity against the filamentous fungus, Mucor mucedo IFO 7684, accompanied by hyphal morphological changes such as swollen hyphae at the tips. Its minimum growth inhibitory concentration was 0.625 mM. A hyperosmotic condition (1.2 M sorbitol) restricted the induction of morphological changes, while hypoosmotic treatment (distilled water) induced bursting of hyphal tips and leakage of cytoplasmic constituents. Furthermore, anethole dose-dependently inhibited chitin synthase (CHS) activity in permeabilized hyphae in an uncompetitive manner. These results suggest that the morphological changes of M. mucedo could be explained by the fragility of cell walls caused by CHS inhibition.

  5. Study on Na layer response to geomagnetic activities based on Odin/OSIRIS Na density data

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo; Nakamura, Takuji; Hedin, Jonas; Gumbel, Jorg; Hosokawa, Keisuke; Ejiri, Mitsumu K.; Nishiyama, Takanori; Takahashi, Toru

    2016-07-01

    The Na layer is normally distributed from 80 to 110 km, and the height range is corresponding to the ionospheric D and E region. In the polar region, the energetic particles precipitating from the magnetosphere can often penetrate into the E region and even into the D region. Thus, the influence of the energetic particles to the Na layer is one of interests in the aspect of the atmospheric composition change accompanied with the auroral activity. There are several previous studies in this issue. For example, recently, we have reported an initial result on a clear relationship between the electron density increase (due to the energetic particles) and the Na density decrease from observational data sets obtained by Na lidar, EISCAT VHF radar, and optical instruments at Tromsoe, Norway on 24-25 January 2012. However, all of the previous studies had been carried out based on case studies by ground-based lidar observations. In this study, we have performed, for the first time, statistical analysis using Na density data from 2004 to 2009 obtained with the Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin satellite. In the presentation, we will show relationship between the Na density and geomagnetic activities, and its latitudinal variation. Based on these results, the Na layer response to the energetic particles will be discussed.

  6. Enhancing the performance of nanofiltration membranes by modifying the active layer with aramide dendrimers.

    PubMed

    de Jubera, Ana M Saenz; Gao, Yuan; Moore, Jeffrey S; Cahill, David G; Mariñas, Benito J

    2012-09-01

    The fully aromatic polyamide active layer of a commercial nanofiltration membrane was modified with three generations (G1, G2, and G3) of aramide dendrimers, all with oligoethylene glycol chains on their peripheries. Permeation experiments revealed that the rejection of Rhodamine WT, used as a surrogate for organic contaminants, improved 1-2 orders of magnitude for membranes modified with G2 and G3 dendrimers at loadings of 0.7-3.5 μg/cm(2) (dendrimer layer thicknesses of ~1-6 nm) compared to the performance of unmodified membranes. In contrast, the corresponding water permeability of dendrimer-modified membranes decreased by only ~30%. Although an enhancement in the rejection of H(3)AsO(3), NaCl, and BaCl(2) was also observed for dendritic membranes, the effect was less pronounced than that for rhodamine WT. Characterization of membranes modified with 3.5 μg/cm(2) dendrimers G2 and G3 by Rutherford backscattering spectrometry with the aid of heavy ion probes (Ag(+) and Ba(2+)) revealed that accessibility of the larger Ba(2+) probe to carboxylate groups on the active layer decreased for the membranes modified with dendrimers.

  7. Statistical analysis on Na layer response to geomagnetic activities using Odin/OSIRIS data

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo T.; Nakamura, Takuji; Ejiri, Mitsumu K.; Nishiyama, Takanori; Hosokawa, Keisuke; Takahashi, Toru; Gumbel, Jörg; Hedin, Jonas

    2016-04-01

    The Na layer is normally distributed from 80 to 110 km, and the height range is corresponding to the ionospheric D and E region. In the polar region, the energetic particles precipitating from the magnetosphere can often penetrate into the E region and even into the D region. Thus, the influence of the energetic particles to the Na layer is one of interests in the aspect of the atmospheric composition change accompanied with the auroral activity. There are several previous studies in this issue. For example, recently, we have reported an initial result on a clear relationship between the electron density increase (due to the energetic particles) and the Na density decrease from observational dataset obtained by Na lidar, EISCAT VHF radar, and optical instruments at Tromsoe, Norway on 24-25 January 2012. However, all of the previous studies had been carried out based on case studies by ground-based lidar observations. In this study, we have performed, for the first time, statistical analysis using Na density data from 2004 to 2009 obtained with the Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin satellite. In the presentation, we will show relationship between the Na density and geomagnetic activities, and its latitudinal variation. Based on these results, the Na layer response to the energetic particles will be discussed.

  8. Design method of the layered active magnetic regenerator (AMR) for hydrogen liquefaction by numerical simulation

    NASA Astrophysics Data System (ADS)

    Park, Inmyong; Kim, Youngkwon; Park, Jiho; Jeong, Sangkwon

    2015-09-01

    The design procedure of an active magnetic regenerator (AMR) operating between liquid nitrogen temperature and liquid hydrogen temperature is discussed with the selected magnetic refrigerants. Selected magnetic refrigerants (GdNi2, Dy0.85Er0.15Al2, Dy0.5Er0.5Al2, and Gd0.1Dy0.9Ni2) that have different transition temperatures are layered in an AMR to widen the temperature span. The optimum volume fraction of the layered refrigerants for the maximum COP with minimum volume is designed in a two-stage active magnetic regenerative refrigerator (AMRR) using one dimensional numerical simulation. The entropy generation in each stage of the AMR is calculated by the numerical simulation to optimize the proposed design. The main sources of the entropy generation in the AMR are pressure drop, convection and conduction heat transfers in the AMR. However, the entropy generation by the convective heat transfer is mostly dominant in the optimized cases. In this paper, the design parameters and the operating conditions such as the distribution of the selected refrigerants in the layered AMR, the intermediate temperature between two stages and the mass flow rate of heat transfer fluid are specifically determined to maximize the performance of the AMR. The proposed design method will facilitate the construction of AMR systems with various magnetic refrigerants and conditions such as AMR size, operating temperature range, and magnetic field variation.

  9. Layer V Perirhinal Cortical Ensemble Activity during Object Exploration: A Comparison between Young and Aged Rats

    PubMed Central

    Burke, S.N.; Hartzell, A.L.; Lister, J.P.; Hoang, L.T.; Barnes, C.A.

    2012-01-01

    Object recognition memory requires the perirhinal cortex (PRC) and this cognitive function declines during normal aging. Recent electrophysiological recordings from young rats have shown that neurons in layer V of the PRC are activated by 3-dimensional objects. Thus, it is possible that age-related object recognition deficits result from alterations in PRC neuron activity in older animals. To examine this, the present study used cellular compartment analysis of temporal activity by fluorescence in situ hybridization (catFISH) with confocal microscopy to monitor cellular distributions of activity-induced Arc RNA in layer V of the PRC. Activity was monitored during two distinct epochs of object exploration. In one group of rats (6 young/6 aged) animals were placed in a familiar testing arena and allowed to explore five different 3-dimensional objects for two 5-min sessions separated by a 20-min rest (AA). The second group of animals (6 young/6 aged) also explored the same objects for two 5-min sessions, but the environment was changed between the first and the second epoch (AB). Behavioral data showed that both age groups spent less time exploring objects during the second epoch, even when the environment changed, indicating successful recognition. Although the proportion of active neurons between epochs did not change in the AA group, in the AB group more neurons were active during epoch 2 of object exploration. This recruitment of neurons into the active neural ensemble could serve to signal that familiar stimuli are being encountered in a new context. When numbers of Arc positive neurons were compared between age groups, the old rats had significantly lower proportions of Arc-positive PRC neurons in both the AA and AB behavioral conditions. These data support the hypothesis that age-associated functional alterations in the PRC contribute to declines in stimulus recognition over the lifespan. PMID:22987683

  10. Layer V perirhinal cortical ensemble activity during object exploration: a comparison between young and aged rats.

    PubMed

    Burke, S N; Hartzell, A L; Lister, J P; Hoang, L T; Barnes, C A

    2012-10-01

    Object recognition memory requires the perirhinal cortex (PRC) and this cognitive function declines during normal aging. Recent electrophysiological recordings from young rats have shown that neurons in Layer V of the PRC are activated by three-dimensional objects. Thus, it is possible that age-related object recognition deficits result from alterations in PRC neuron activity in older animals. To examine this, the present study used cellular compartment analysis of temporal activity by fluorescence in situ hybridization (catFISH) with confocal microscopy to monitor cellular distributions of activity-induced Arc RNA in layer V of the PRC. Activity was monitored during two distinct epochs of object exploration. In one group of rats (6 young/6 aged) animals were placed in a familiar testing arena and allowed to explore five different three-dimensional objects for two 5-min sessions separated by a 20-min rest (AA). The second group of animals (6 young/6 aged) also explored the same objects for two 5-min sessions, but the environment was changed between the first and the second epoch (AB). Behavioral data showed that both age groups spent less time exploring objects during the second epoch, even when the environment changed, indicating successful recognition. Although the proportion of active neurons between epochs did not change in the AA group, in the AB group more neurons were active during epoch 2 of object exploration. This recruitment of neurons into the active neural ensemble could serve to signal that familiar stimuli are being encountered in a new context. When numbers of Arc positive neurons were compared between age groups, the old rats had significantly lower proportions of Arc-positive PRC neurons in both the AA and AB behavioral conditions. These data support the hypothesis that age-associated functional alterations in the PRC contribute to declines in stimulus recognition over the lifespan.

  11. Rosetta/OSIRIS: Nucleus morphology and activity of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Sierks, Holger

    2015-08-01

    Introduction: The Rosetta mission of the European Space Agency arrived on August 6, 2014, at the target comet 67P/Churyumov-Gerasimenko after 10 years of cruise. OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) is the scientific imaging system onboard Rosetta. It comprises a Narrow Angle Camera (NAC) for broad-band nucleus surface and dust studies and a Wide Angle Camera (WAC) for the wide field coma investigations.OSIRIS images the nucleus and the coma of comet 67P/C-G from the arrival throughout early mapping phase, PHILAE landing, and escort phase with close fly-by beginning of the year 2015.The team paper presents the surface morphology and activity of the nucleus as seen in gas, dust, and local jets and the larger scale coma studied by OSIRIS.Acknowledgements: OSIRIS was built by a consortium led by the Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany, in collaboration with CISAS, University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofísica de Andalucia, CSIC, Granada, Spain, the Scientific Support Office of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Técnica Aeroespacial, Madrid, Spain, the Universidad Politéchnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut für Datentechnik und Kommunikationsnetze der Technischen Universität Braunschweig, Germany.Additional Information: The OSIRIS team is H. Sierks, C. Barbieri, P. Lamy, R. Rodrigo, D. Koschny, H. Rickman, J. Agarwal, M. A'Hearn, I. Bertini, F. Angrilli, M. A. Barucci, J. L. Bertaux, G. Cremonese, V. Da Deppo, B. Davidsson, S. Debei, M. De Cecco, S. Fornasier, M. Fulle, O. Groussin, C. Güttler, P. Gutierrez, S. Hviid, W. Ip, L. Jorda, H. U. Keller, J. Knollenberg, R. Kramm, E. Kührt, M. Küppers, L. Lara, M. Lazzarin, J. J. Lopez, S. Lowry, S. Marchi, F. Marzari, H. Michalik, S. Mottola, G. Naletto, N. Oklay, L

  12. Low-noise encoding of active touch by layer 4 in the somatosensory cortex.

    PubMed

    Hires, Samuel Andrew; Gutnisky, Diego A; Yu, Jianing; O'Connor, Daniel H; Svoboda, Karel

    2015-08-06

    Cortical spike trains often appear noisy, with the timing and number of spikes varying across repetitions of stimuli. Spiking variability can arise from internal (behavioral state, unreliable neurons, or chaotic dynamics in neural circuits) and external (uncontrolled behavior or sensory stimuli) sources. The amount of irreducible internal noise in spike trains, an important constraint on models of cortical networks, has been difficult to estimate, since behavior and brain state must be precisely controlled or tracked. We recorded from excitatory barrel cortex neurons in layer 4 during active behavior, where mice control tactile input through learned whisker movements. Touch was the dominant sensorimotor feature, with >70% spikes occurring in millisecond timescale epochs after touch onset. The variance of touch responses was smaller than expected from Poisson processes, often reaching the theoretical minimum. Layer 4 spike trains thus reflect the millisecond-timescale structure of tactile input with little noise.

  13. On Active Layer Environments and Processes in Western Dronning Maud Land, Antarctica

    NASA Astrophysics Data System (ADS)

    Hansen, C. D.; Meiklejohn, I.; Nel, W.

    2012-12-01

    The current understanding of Antarctic permafrost is poor, particularly regarding its evolution, the current thermal characteristics, and relationships with pedogenesis, hydrology, geomorphic, dynamics, biotic activity and response to global changes. Results from borehole temperature measurements over a four-year period in Western Dronning Maud Land suggest that the active layer depth is dependent on the substrate, latitude, altitude and the volume of ground exposed; the latter alludes to the potential impact of surrounding ice on the ground thermal regime. The active layer depths at the monitoring sites, varied between 16 cm at Vesleskarvet, a small nunatak at 850 masl to 28 cm in granitic till at Jutulsessen (1 270 masl). The mean near surface (1.5 cm depth) ground temperatures from 2009 to 2012 in the region have a narrow range from -16.4°C at 850m to -17.5°C at 1270 masl. Permafrost temperatures for the same locations vary between -16.3°C and -18.3°C. While little variability exists between the mean temperatures at the study locations, each site is distinct and seasonal and shorter-term frost cycles have produced landforms that are characteristic of both permafrost and diurnal frost environments. One of the key aspects of investigation is the control that the active layer has on autochthonous blockfield development in the region. The, thus far, exploratory research is being used to understand controls on the landscape and the relationship between distribution and abundance of biota. Given the rapidly changing climates in the region, improving knowledge of what drives patterns of biodiversity at a local and regional scale is vital to assess consequences of environmental change.

  14. The Influence of Surface-Active Agent on the Micro-Morphology and Crystallinity of Spherical Hexagonal Boron Nitride.

    PubMed

    Zhang, Ning; Liu, Huan; Kan, Hongmin; Wang, Xiaoyang; Long, Haibo; Zhou, Yonghui

    2015-08-01

    This search used the low-cost boric acid and borax as a source of boron, urea as a nitrogen source, surface-active agent Dodecyl benzenesulfonic acid (SDBS) as a dispersant, and thus prepared different micro-morphology and crystallinity hexagonal boron nitride powders under a flowing ammonia atmosphere at a nitriding temperature of 900 °C. The effect of the surface-active agent (SDBS) content on the crystallinity and micro-morphology of hexagonal boron nitride powders was studied, and the corresponding relationship between micro-morphology and crystallinity was explored. The results showed that under a certain synthetic process (900 °C for 3 h), the surfactant content had affected the crystallinity and micro-morphology of h-BN powders. Without the added surfactant, the graphitization index (GI) was 3.61, and micro-morphology of h-BN powders. was spherical, the distribution of ball diameters was uneven, and there was also significant particle agglomeration, with some particles even exhibiting adhesion, sintering necks, and high sphericity and diameter. When the added SDBS percentages were 2%, 4% and 6%, the graphitization index (GI) decreased to 2.98, 2.58 and 2.41 respectively: the corresponding crystallinity improved significantly. When the surfactant SDBS content was higher (10%), the diameter distribution of the h-BN powders was even, but there was evidence of agglomeration of particles and particle adhesion. The crystallinity decreased when the GI value was increased to 4. When the surfactant SDBS content was 6%, the dispersion of h-BN powders was at its optimum, and the particle size distribution was at its most uniform. Meanwhile the GI value was at its lowest, and the crystallinity at its highest. PMID:26369229

  15. Effect of synthesis temperature on the morphology, structure and photocatalytic activity of TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Nayak, J.; Mohapatra, A. K.; Kim, Heeje

    2015-06-01

    Nanocrystals of TiO2 were synthesized by a single-step chemical reaction between oleic acid and titanium (IV) iso-propoxide. The morphology and structure of the crystals were studied by X-ray diffraction and transmission electron microscopy. The vibrational properties of the nanocrystals were studied by Raman spectroscopy. The ultraviolet photocatalytic activity of the TiO2 nanocrystals was investigated by studying the photodegradation of aqueous solution of protocatecheuic acid (3,4-dihydroxy benzoic acid).

  16. Heterostructured Au/Pd-M (M = Au, Pd, Pt) nanoparticles with compartmentalized composition, morphology, and electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Lutz, Patrick S.; Bae, In-Tae; Maye, Mathew M.

    2015-09-01

    The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had high activity attributed to the porous nature of the platinum domains.The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had

  17. Active layer thermal monitoring at Fildes Peninsula, King George Island, Maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Michel, Roberto; Schaefer, Carlos; Simas, Felipe; Pregesbauer, Michael; Bockheim, James

    2013-04-01

    International attention on the climate change phenomena has grown in the last decade, intense modelling of climate scenarios were carried out by scientific investigations searching the sources and trends of these changes. The cryosphere and its energy flux became the focus of many investigations, being recognised as a key element for the understanding of future trends. The active layer and permafrost are key components of the terrestrial cryosphere due to their role in energy flux regulation and high sensitivity to climate change (Kane et al., 2001; Smith and Brown, 2009). Compared with other regions of the globe, our understanding of Antarctic permafrost is poor, especially in relation to its thermal state and evolution, its physical properties, links to pedogenesis, hydrology, geomorphic dynamics and response to global change (Bockheim, 1995, Bockheim et al., 2008). The active layer monitoring site was installed in the summer of 2008, and consist of thermistors (accuracy ± 0.2 °C) arranged in a vertical array (Turbic Eutric Cryosol 600 m asl, 10.5 cm, 32.5 cm, 67.5 cm and 83.5 cm). King George Island experiences a cold moist maritime climate characterized by mean annual air temperatures of -2°C and mean summer air temperatures above 0°C for up to four months (Rakusa-Suszczewski et al., 1993, Wen et al., 1994). Ferron et al., (2004) found great variability when analysing data from 1947 to1995 and identified cycles of 5.3 years of colder conditions followed by 9.6 years of warmer conditions. All probes were connected to a Campbell Scientific CR 1000 data logger recording data at hourly intervals from March 1st 2008 until November 30th 2012. Meteorological data for Fildes was obtained from the near by stations. We calculated the thawing days, freezing days; thawing degree days and freezing degree days; all according to Guglielmin et al. (2008). The active lawyer thickness was calculated as the 0 °C depth by extrapolating the thermal gradient from the two

  18. CANDELS: THE CORRELATION BETWEEN GALAXY MORPHOLOGY AND STAR FORMATION ACTIVITY AT z {approx} 2

    SciTech Connect

    Lee, Bomee; Giavalisco, Mauro; Williams, Christina C.; Guo Yicheng; Faber, S. M.; Van der Wel, Arjen; Kocevski, Dale; Conselice, Christopher J.; Wuyts, Stijn; Dekel, Avishai; Kartaltepe, Jeyhan; Bell, Eric F.

    2013-09-01

    We discuss the state of the assembly of the Hubble sequence in the mix of bright galaxies at redshift 1.4 < z {<=} 2.5 with a large sample of 1671 galaxies down to H{sub AB} {approx} 26, selected from the HST/ACS and WFC3 images of the GOODS-South field obtained as part of the GOODS and CANDELS observations. We investigate the relationship between the star formation properties and morphology using various parametric diagnostics, such as the Sersic light profile, Gini (G), M{sub 20}, concentration (C), asymmetry (A), and multiplicity ({Psi}) parameters. Our sample clearly separates into massive, red, and passive galaxies versus less massive, blue, and star-forming ones, and this dichotomy correlates very well with the galaxies' morphological properties. Star-forming galaxies show a broad variety of morphological features, including clumpy structures and bulges mixed with faint low surface brightness features, generally characterized by disky-type light profiles. Passively evolving galaxies, on the other hand, very often have compact light distribution and morphology typical of today's spheroidal systems. We also find that artificially redshifted local galaxies have a similar distribution with z {approx} 2 galaxies in a G-M{sub 20} plane. Visual inspection between the rest-frame optical and UV images show that there is a generally weak morphological k-correction for galaxies at z {approx} 2, but the comparison with non-parametric measures show that galaxies in the rest-frame UV are somewhat clumpier than rest-frame optical. Similar general trends are observed in the local universe among massive galaxies, suggesting that the backbone of the Hubble sequence was already in place at z {approx} 2.

  19. Solution-processed flexible planar perovskite solar cells: A strategy to enhance efficiency by controlling the ZnO electron transfer layer, PbI2 phase, and CH3NH3PbI3 morphologies

    NASA Astrophysics Data System (ADS)

    Jung, Kyungeun; Lee, Jeongwon; Kim, Joosun; Chae, Weon-Sik; Lee, Man-Jong

    2016-08-01

    This paper reports a synergistic strategy to enhance the power conversion efficiency (PCE) of flexible planar perovskite solar cells (PSCs) by controlling the thickness of the ZnO electron transport layer (ETL), PbI2 phase, and size/morphology of the perovskite (MAPbI3) absorber layer. To optimize the size/morphology of MAPbI3 via a two-step spin coating process, various volumes of CH3NH3I precursor solutions with a constant concentration were continuously coated, which greatly affected the grain growth condition of the MAPbI3. In addition, the remnant PbI2 phase in the MAPbI3, which acted as a recombination barrier, was simultaneously controlled. This strategic method to synergistically combine the major factors affecting the final PCE resulted in the best efficiency of 12.3%, which is the highest efficiency among ZnO-ETL-based flexible planar PSCs to date.

  20. Role of interfacial friction for flow instabilities in a thin polar-ordered active fluid layer

    NASA Astrophysics Data System (ADS)

    Sarkar, Niladri; Basu, Abhik

    2015-11-01

    We construct a generic coarse-grained dynamics of a thin inflexible planar layer of polar-ordered suspension of active particles that is frictionally coupled to an embedding isotropic passive fluid medium with a friction coefficient Γ . Being controlled by Γ , our model provides a unified framework to describe the long-wavelength behavior of a variety of thin polar-ordered systems, ranging from wet to dry active matter and free-standing active films. Investigations of the linear instabilities around a chosen orientationally ordered uniform reference state reveal generic moving and static instabilities in the system that can depend sensitively on Γ . Based on our results, we discuss estimation of bounds on Γ in experimentally accessible systems.

  1. Hot-Film and Hot-Wire Anemometry for a Boundary Layer Active Flow Control Test

    NASA Technical Reports Server (NTRS)

    Lenahan, Keven C.; Schatzman, David M.; Wilson, Jacob Samuel

    2013-01-01

    Unsteady active flow control (AFC) has been used experimentally for many years to minimize bluff-body drag. This technology could significantly improve performance of rotorcraft by cleaning up flow separation. It is important, then, that new actuator technologies be studied for application to future vehicles. A boundary layer wind tunnel was constructed with a 1ft-x-3ft test section and unsteady measurement instrumentation to study how AFC manipulates the boundary layer to overcome adverse pressure gradients and flow separation. This unsteady flow control research requires unsteady measurement methods. In order to measure the boundary layer characteristics, both hot-wire and hot-film Constant Temperature Anemometry is used. A hot-wire probe is mounted in the flow to measure velocity while a hot-film array lays on the test surface to measure skin friction. Hot-film sensors are connected to an anemometer, a Wheatstone bridge circuit with an output that corresponds to the dynamic flow response. From this output, the time varying flow field, turbulence, and flow reversal can be characterized. Tuning the anemometers requires a fan test on the hot-film sensors to adjust each output. This is a delicate process as several variables drastically affect the data, including control resistance, signal input, trim, and gain settings.

  2. Evidence for reduced charge recombination in carbon nanotube/perovskite-based active layers

    NASA Astrophysics Data System (ADS)

    Bag, Monojit; Renna, Lawrence A.; Jeong, Seung Pyo; Han, Xu; Cutting, Christie L.; Maroudas, Dimitrios; Venkataraman, D.

    2016-10-01

    Using impedance spectroscopy and computation, we show that incorporation of multi-walled carbon nanotubes (MWCNTs) in the bulk of the active layer of perovskite-based solar cells reduces charge recombination and increases the open circuit voltage. An ∼87% reduction in recombination was achieved when MWCNTs were introduced in the planar-heterostructure perovskite solar cell containing mixed counterions. The open circuit voltage (Voc) of perovskite/MWCNTs devices was increased by 70 mV, while the short circuit current density (Jsc) and fill factor (FF) remained unchanged.

  3. Improved Power Conversion Efficiency of Inverted Organic Solar Cells by Incorporating Au Nanorods into Active Layer.

    PubMed

    He, Yeyuan; Liu, Chunyu; Li, Jinfeng; Zhang, Xinyuan; Li, Zhiqi; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2015-07-29

    This Research Article describes a cooperative plasmonic effect on improving the performance of organic solar cells. When Au nanorods(NRs) are incorporated into the active layers, the designed project shows superior enhanced light absorption behavior comparing with control devices, which leads to the realization of organic solar cell with power conversion efficiency of 6.83%, accounting for 18.9% improvement. Further investigations unravel the influence of plasmonic nanostructures on light trapping, exciton generation, dissociation, and charge recombination and transport inside the thin films devices. Moreover, the introduction of high-conductivity Au NRs improves electrical conductivity of the whole device, which contributes to the enhanced fill factor.

  4. Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 2--morphological and mineralogical features.

    PubMed

    Calabrese, S; D'Alessandro, W

    2015-01-01

    Volcanic emissions were studied at Mount Etna (Italy) by using moss-bags technique. Mosses were exposed around the volcano at different distances from the active vents to evaluate the impact of volcanic emissions in the atmosphere. Morphology and mineralogy of volcanic particulate intercepted by mosses were investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Particles emitted during passive degassing activity from the two active vents, Bocca Nuova and North East Crater (BNC and NEC), were identified as silicates, sulfates and halide compounds. In addition to volcanic particles, we found evidences also of geogenic, anthropogenic and marine spray input. The study has shown the robustness of this active biomonitoring technique to collect particles, very useful in active volcanic areas characterized by continuous degassing and often not easily accessible to apply conventional sampling techniques.

  5. Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 2--morphological and mineralogical features.

    PubMed

    Calabrese, S; D'Alessandro, W

    2015-01-01

    Volcanic emissions were studied at Mount Etna (Italy) by using moss-bags technique. Mosses were exposed around the volcano at different distances from the active vents to evaluate the impact of volcanic emissions in the atmosphere. Morphology and mineralogy of volcanic particulate intercepted by mosses were investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Particles emitted during passive degassing activity from the two active vents, Bocca Nuova and North East Crater (BNC and NEC), were identified as silicates, sulfates and halide compounds. In addition to volcanic particles, we found evidences also of geogenic, anthropogenic and marine spray input. The study has shown the robustness of this active biomonitoring technique to collect particles, very useful in active volcanic areas characterized by continuous degassing and often not easily accessible to apply conventional sampling techniques. PMID:25311770

  6. Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique

    SciTech Connect

    Hazra, Purnima; Singh, Satyendra Kumar; Jit, Satyabrata

    2015-01-01

    In this paper, the authors have investigated the structural, optical, and electrical characteristics of silicon nanowire (SiNW)/zinc oxide (ZnO) core–shell nanostructure heterojunctions and compared their characteristics with Si/ZnO planar heterojunctions to investigate the effect of surface morphology of Si substrate in the characteristics of Si/ZnO heterojunction devices. In this work, ZnO thin film was conformally deposited on both p-type 〈100〉 planar Si substrate and substrate with vertically aligned SiNW arrays by atomic layer deposition (ALD) method. The x-ray diffraction spectra show that the crystalline structures of Si/ZnO heterojunctions are having (101) preferred orientation, whereas vertically oriented SiNW/ZnO core–shell heterojunctions are having (002)-oriented wurtzite crystalline structures. The photoluminescence (PL) spectra of Si/ZnO heterojunctions show a very sharp single peak at 377 nm, corresponding to the bandgap of ZnO material with no other defect peaks in visible region; hence, these devices can have applications only in UV region. On the other hand, SiNW/ZnO heterojunctions are having band-edge peak at 378 nm along with a broad emission band, spreading almost throughout the entire visible region with a peak around 550 nm. Therefore, ALD-grown SiNW/ZnO heterojunctions can emit green and red light simultaneously. Reflectivity measurement of the heterojunctions further confirms the enhancement of visible region peak in the PL spectra of SiNW/ZnO heterojunctions, as the surface of the SiNW/ZnO heterojunctions exhibits extremely low reflectance (<3%) in the visible wavelength region compared to Si/ZnO heterojunctions (>20%). The current–voltage characteristics of both Si/ZnO and SiNW/ZnO heterojunctions are measured with large area ohmic contacts on top and bottom of the structure to compare the electrical characteristics of the devices. Due to large surface to-volume ratio of SiNW/ZnO core–shell heterojunction devices, the

  7. Active Layer Thawing and Freeze-Back in Svalbard using DC Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Oswald, A.; Juliussen, H.; Christiansen, H. H.

    2009-04-01

    The thawing of the active layer has an important impact on the permafrost below, since the state of the uppermost soil layers determines how large surface temperature fluctuations are translated to deeper ground. Latent heat and combined liquid water and energy transport during the thawing season influence the energy exchange between permafrost and atmosphere. A first step to a better understanding of these processes is to determine the depth of the active layer and its thermal state the best possible way. Borehole temperatures give a very accurate measure of the ground thermal state but are, like active layer depths from mechanical probing, single point measurements. Geophysical imaging methods, such as DC resistivity tomography, allow for a 2d-image of subsurface soil properties, but should be supplemented with point temperature measurements as the results might be ambiguous. In spring and late summer 2007 electrode arrays have been permanently installed in three different permafrost landforms in Svalbard (a gently sloping solifluction sheet, a valley bottom loess terrace and a vertical sandstone rockwall) as a part of the IPY-project - ‘Permafrost Observatory Project: A Contribution to the Thermal State of Permafrost in Norway and Svalbard' TSP Norway. With a spacing of 20cm and a total array length of 16m this allows for a maximum measurement depth of about 2.5m. During most parts of IPY measurements were carried on a more or less regular basis - ideally in a two weeks interval. While measurements in the rockwall suffered from permanent loosening of the electrodes in the brittle sandstone, the measurements on the loess terrace and the solifluction slope were only interrupted during the very cold spring conditions as grounding errors occurred. Hence field work focused on the loess terrace and the solifluction sheet - the former consisting of silt and fine clay; the latter characterized by its high water content and a rather heterogeneous grain size

  8. Plastic solar cell interface and morphological characterization

    NASA Astrophysics Data System (ADS)

    Guralnick, Brett W.

    Plastic solar cell research has become an intense field of study considering these devices may be lightweight, flexible and reduce the cost of photovoltaic devices. The active layer of plastic solar cells are a combination of two organic components which blend to form an internal morphology. Due to the poor electrical transport properties of the organic components it is important to understand how the morphology forms in order to engineer these materials for increased efficiency. The focus of this thesis is a detailed study of the interfaces between the plastic solar cell layers and the morphology of the active layer. The system studied in detail is a blend of P3HT and PCBM that acts as the primary absorber, which is the electron donor, and the electron acceptor, respectively. The key morphological findings are, while thermal annealing increases the crystallinity parallel to the substrate, the morphology is largely unchanged following annealing. The deposition and mixing conditions of the bulk heterojunction from solution control the starting morphology. The spin coating speed, concentration, solvent type, and solution mixing time are all critical variables in the formation of the bulk heterojunction. In addition, including the terminals or inorganic layers in the analysis is critical because the inorganic surface properties influence the morphology. Charge transfer in the device occurs at the material interfaces, and a highly resistive transparent conducting oxide layer limits device performance. It was discovered that the electron blocking layer between the transparent conducting oxide and the bulk heterojunction is compromised following annealing. The electron acceptor material can diffuse into this layer, a location which does not benefit device performance. Additionally, the back contact deposition is important since the organic material can be damaged by the thermal evaporation of Aluminum, typically used for plastic solar cells. Depositing a thin thermal and

  9. Morphology dependent catalytic activity of TiO{sub 2} nanostructures towards photodegradation of Rose Bengal

    SciTech Connect

    Malik, Ritu; Kumar, Ashok; Rana, Pawan S.; Nehra, S. P.

    2015-08-28

    This work deals with the synthesis of TiO{sub 2} nanostructures using sol-gel and hydrothermal method for evaluating their photodegradation performance towards decolorization of Rose Bengal (RB). A combination of characterization techniques including X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and UV–Vis spectroscopy were utilized to evaluate the structural, morphological and optical properties of the obtained nanostructures. It was observed that the TiO{sub 2} nanoparticles prepared using hydrothermal method were highly crystalline and possess higher band gap value, even when same conditions of temperature, pressure, precursor ratios and solvent amount was kept constant while synthesizing TiO{sub 2} nanostructures via sol-gel method. The obvious effect of porous morphology exhibited by TiO{sub 2} nanoparticles prepared using hydrothermal route is reflected in its decolorization performance whereby 92.5% of the RB dye solution was degraded in 70 min of irradiation time.

  10. Morphology dependent catalytic activity of TiO2 nanostructures towards photodegradation of Rose Bengal

    NASA Astrophysics Data System (ADS)

    Malik, Ritu; Kumar, Ashok; Nehra, S. P.; Rana, Pawan S.

    2015-08-01

    This work deals with the synthesis of TiO2 nanostructures using sol-gel and hydrothermal method for evaluating their photodegradation performance towards decolorization of Rose Bengal (RB). A combination of characterization techniques including X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy were utilized to evaluate the structural, morphological and optical properties of the obtained nanostructures. It was observed that the TiO2 nanoparticles prepared using hydrothermal method were highly crystalline and possess higher band gap value, even when same conditions of temperature, pressure, precursor ratios and solvent amount was kept constant while synthesizing TiO2 nanostructures via sol-gel method. The obvious effect of porous morphology exhibited by TiO2 nanoparticles prepared using hydrothermal route is reflected in its decolorization performance whereby 92.5% of the RB dye solution was degraded in 70 min of irradiation time.

  11. Morphology-dependent photocatalytic activity of octahedral anatase particles prepared by ultrasonication-hydrothermal reaction of titanates

    NASA Astrophysics Data System (ADS)

    Wei, Zhishun; Kowalska, Ewa; Verrett, Jonathan; Colbeau-Justin, Christophe; Remita, Hynd; Ohtani, Bunsho

    2015-07-01

    Octahedral anatase particles (OAPs) were prepared by an ultrasonication (US)-hydrothermal (HT) reaction of partially proton-exchanged potassium titanate nanowires (TNWs). The structural/physical properties of OAP-containing samples, including specific surface area, crystallinity, crystallite size, particle aspect ratio, composition and total OAP content, were analyzed. Photocatalytic activities of samples were measured under irradiation (>290 nm) for oxidative decomposition of acetic acid (CO2 system) and dehydrogenation of methanol (H2 system) under aerobic and deaerated conditions, respectively. Total density of electron traps (ETs) was measured by double-beam photoacoustic spectroscopy (DB-PAS). Mobility and lifetime of charge carriers (electrons) were investigated by the time-resolved microwave conductivity (TRMC) method. The effects of synthesis parameters, i.e., HT duration, HT temperature and US duration, on properties and photocatalytic activities of final products were examined in detail. The sample prepared with 1 h US duration and 6 h HT duration at 433 K using 267 mg of TNWs in 80 mL of Milli-Q water exhibited the highest photocatalytic activity. It was found that change in HT duration or HT temperature while keeping the other conditions the same resulted in changes in all properties and photocatalytic activity. On the other hand, duration of US treatment, before HT reaction, influenced the morphology of both the reagent (by TNWs breaking) and final products (change in total OAP content); samples prepared with various US durations exhibited almost the same structural/physical properties evaluated in this study but were different in morphology and photocatalytic activity. This enabled clarification of the correlation between morphology and photocatalytic activity, i.e., the higher the total OAP content was, the higher was the level of photocatalytic activity, especially in the CO2 system. Although the decay after maximum TRMC signal intensity (Imax) was

  12. Tuning the morphology, stability and photocatalytic activity of TiO{sub 2} nanocrystal colloids by tungsten doping

    SciTech Connect

    Xu, Haiping; Liao, Jianhua; Yuan, Shuai; Zhao, Yin; Zhang, Meihong; Wang, Zhuyi; Shi, Liyi

    2014-03-01

    Graphical abstract: - Highlights: • W{sup 6+}-doped TiO{sub 2} nanocrystal colloids were prepared by hydrothermal methods. • The properties of TiO{sub 2} nanocrystal colloids can be tuned by tungsten doping. • W{sup 6+}-doped TiO{sub 2} nanocrystal colloids show higher stability and dispersity. • W{sup 6+}-doped TiO{sub 2} nanocrystal colloids show higher photocatalytic activity. - Abstract: The effects of tungsten doping on the morphology, stability and photocatalytic activity of TiO{sub 2} nanocrystal colloids were investigated. The nanostructure, chemical state of Ti, W, O, and the properties of tungsten doped TiO{sub 2} samples were investigated carefully by TEM, XRD, XPS, UV–vis, PL and photocatalytic degradation experiments. And the structure–activity relationship was discussed according to the analysis and measurement results. The analysis results reveal that the morphology, zeta potential and photocatalytic activity of TiO{sub 2} nanocrystals can be easily tuned by changing the tungsten doping concentration. The tungsten doped TiO{sub 2} colloid combines the characters of high dispersity and high photocatalytic activity.

  13. Layer-by-layer grown scalable redox-active ruthenium-based molecular multilayer thin films for electrochemical applications and beyond.

    PubMed

    Kaliginedi, Veerabhadrarao; Ozawa, Hiroaki; Kuzume, Akiyoshi; Maharajan, Sivarajakumar; Pobelov, Ilya V; Kwon, Nam Hee; Mohos, Miklos; Broekmann, Peter; Fromm, Katharina M; Haga, Masa-aki; Wandlowski, Thomas

    2015-11-14

    Here we report the first study on the electrochemical energy storage application of a surface-immobilized ruthenium complex multilayer thin film with anion storage capability. We employed a novel dinuclear ruthenium complex with tetrapodal anchoring groups to build well-ordered redox-active multilayer coatings on an indium tin oxide (ITO) surface using a layer-by-layer self-assembly process. Cyclic voltammetry (CV), UV-Visible (UV-Vis) and Raman spectroscopy showed a linear increase of peak current, absorbance and Raman intensities, respectively with the number of layers. These results indicate the formation of well-ordered multilayers of the ruthenium complex on ITO, which is further supported by the X-ray photoelectron spectroscopy analysis. The thickness of the layers can be controlled with nanometer precision. In particular, the thickest layer studied (65 molecular layers and approx. 120 nm thick) demonstrated fast electrochemical oxidation/reduction, indicating a very low attenuation of the charge transfer within the multilayer. In situ-UV-Vis and resonance Raman spectroscopy results demonstrated the reversible electrochromic/redox behavior of the ruthenium complex multilayered films on ITO with respect to the electrode potential, which is an ideal prerequisite for e.g. smart electrochemical energy storage applications. Galvanostatic charge-discharge experiments demonstrated a pseudocapacitor behavior of the multilayer film with a good specific capacitance of 92.2 F g(-1) at a current density of 10 μA cm(-2) and an excellent cycling stability. As demonstrated in our prototypical experiments, the fine control of physicochemical properties at nanometer scale, relatively good stability of layers under ambient conditions makes the multilayer coatings of this type an excellent material for e.g. electrochemical energy storage, as interlayers in inverted bulk heterojunction solar cell applications and as functional components in molecular electronics applications

  14. Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study.

    PubMed

    Paytan, Adina; Lecher, Alanna L; Dimova, Natasha; Sparrow, Katy J; Kodovska, Fenix Garcia-Tigreros; Murray, Joseph; Tulaczyk, Slawomir; Kessler, John D

    2015-03-24

    Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 10(4) nM, 61.6 dpm⋅m(-3), and 4.5 × 10(5) dpm⋅m(-3) compared with 1.3 × 10(2) nM, 5.7 dpm⋅m(-3), and 4.4 × 10(3) dpm⋅m(-3), respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m(-2)⋅y(-1)) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r(2) > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs.

  15. Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

    PubMed Central

    Paytan, Adina; Lecher, Alanna L.; Dimova, Natasha; Sparrow, Katy J.; Kodovska, Fenix Garcia-Tigreros; Murray, Joseph; Tulaczyk, Slawomir; Kessler, John D.

    2015-01-01

    Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 104 nM, 61.6 dpm⋅m−3, and 4.5 × 105 dpm⋅m−3 compared with 1.3 × 102 nM, 5.7 dpm⋅m−3, and 4.4 × 103 dpm⋅m−3, respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m−2⋅y−1) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r2 > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs. PMID:25775530

  16. Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study.

    PubMed

    Paytan, Adina; Lecher, Alanna L; Dimova, Natasha; Sparrow, Katy J; Kodovska, Fenix Garcia-Tigreros; Murray, Joseph; Tulaczyk, Slawomir; Kessler, John D

    2015-03-24

    Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 10(4) nM, 61.6 dpm⋅m(-3), and 4.5 × 10(5) dpm⋅m(-3) compared with 1.3 × 10(2) nM, 5.7 dpm⋅m(-3), and 4.4 × 10(3) dpm⋅m(-3), respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m(-2)⋅y(-1)) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r(2) > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs. PMID:25775530

  17. Ultrahigh Enzyme Activity Assembled in Layered Double Hydroxides via Mg(2+)-Allosteric Effector.

    PubMed

    Wang, Min; Huang, Shu-Wan; Xu, Dan; Bao, Wen-Jing; Xia, Xing-Hua

    2015-06-01

    It is well-known that some metal ions could be allosteric effectors of allosteric enzymes to activate/inhibit the catalytic activities of enzymes. In nanobiocatalytic systems constructed based on the positive metal ion-induced allosteric effect, the incorporated enzymes will be activated and thus exhibit excellent catalytic performance. Herein, we present an environmentally friendly strategy to construct a novel allosteric effect-based β-galactosidase/Mg-Al layered double hydroxide (β-gal/Mg-Al-LDH) nanobiocatalytic system via the delamination-reconstruction method. The intercalated β-gal in the LDH galleries changes its conformation significantly due to the Mg(2+)-induced allosteric interactions and other weak interactions, which causes the activation of enzymatic activity. The β-gal/Mg-Al-LDH nanobiocatalytic system shows much higher catalytic activity and affinity toward its substrate and about 30 times higher catalytic reaction velocity than the free β-gal, which suggests that Mg(2+)-induced allosteric effect plays a vital role in the improvement of enzymatic performance.

  18. Comparative Metagenomic Analysis Of Microbial Communities From Active Layer And Permafrost After Short-Term Thaw

    NASA Astrophysics Data System (ADS)

    Vishnivetskaya, T. A.; Chauhan, A.; Saarunya, G.; Murphy, J.; Williams, D.; Layton, A. C.; Pfiffner, S. M.; Stackhouse, B. T.; Sanders, R.; Lau, C. M.; myneni, S.; Phelps, T. J.; Fountain, A. G.; Onstott, T. C.

    2012-12-01

    .Permafrost areas occupy 20-25% of the Earth and extend of 1 km depths. The total number of prokaryotes and their biomass in cold regions are estimated to be 1 x 1030 cells and 140 x1015 g of C, respectively. Thus these environments serve as a reservoir of microbial and biogeochemical activity, which is likely to increase upon thawing. We are currently performing long-term thawing experiments at 4o C on 18, geochemically well-characterized, 1 meter long, intact cores consisting of active-layer (0-70 cm depth) and permafrost, collected from a 7 meter diameter ice-wedge polygon located at the McGill Arctic Research Station on Axel Heiberg Island, Nunavut, Canada. The organic carbon content of these cores averages ~1% at depth but increases to 5.4% in the top 10 cm. The cores were subdivided into four treatment groups: saturated cores (thawed while receiving artificial rain), drained cores (being thawed under natural hydrological conditions), dark cores (thawed under natural hydrological conditions with no light input) and control cores (maintain permafrost table at 70 cm depth). Over the course of 10 weeks the cores were progressively thawed from -4oC to 4oC from the top down to simulate spring thaw conditions in the Arctic. The temperatures at 5 cm, 35 cm, 65 cm, and below the permafrost table in the core were recorded continuously. Pore water and gas samples from 4 depths in each core were collected every two weeks and analyzed for pH, anions, cations, H2, CH4, CO, O2, N2, CO2 and δ13C of CO2. Headspace gas samples were collected weekly and analyzed for the same gases as the pore gases. Sediment sub-samples from the 4 depths were collected and total community genomic DNA (gDNA) was isolated using FastDNA SPIN kit followed by Qiagen column purification. The average yield of gDNA was ~3.5 μg/g of soil for the upper 5 cm active layers and decreased to ~1.5 μg/g of soil in the permafrost. The bacterial 16S copy numbers estimated by real-time quantitative PCR

  19. Permafrost and active layer monitoring in the maritime Antarctic: Preliminary results from CALM sites on Livingston and Deception Islands

    USGS Publications Warehouse

    Ramos, M.; Vieira, G.; Blanco, J.J.; Hauck, C.; Hidalgo, M.A.; Tome, D.; Nevers, M.; Trindade, A.

    2007-01-01

    This paper describes results obtained from scientific work and experiments performed on Livingston and Deception Islands. Located in the South Shetland Archipelago, these islands have been some of the most sensitive regions over the last 50 years with respect to climate change with a Mean Annual Air Temperature (MAAT) close to -2 ºC. Three Circumpolar Active Layer Monitoring (CALM) sites were installed to record the thermal regime and the behaviour of the active layer in different places with similar climate, but with different soil composition, porosity, and water content. The study’s ultimate aim is to document the influence of climate change on permafrost degradation. Preliminary results, obtained in 2006, on maximum active-layer thickness (around 40 cm in the CALM of Deception Island), active layer temperature evolution, snow thickness, and air temperatures permit early characterization of energy exchange mechanisms between the ground and the atmosphere in the CALM-S sites.

  20. Supramolecular Approaches to Nanoscale Morphological Control in Organic Solar Cells.

    PubMed

    Haruk, Alexander M; Mativetsky, Jeffrey M

    2015-06-11

    Having recently surpassed 10% efficiency, solar cells based on organic molecules are poised to become a viable low-cost clean energy source with the added advantages of mechanical flexibility and light weight. The best-performing organic solar cells rely on a nanostructured active layer morphology consisting of a complex organization of electron donating and electron accepting molecules. Although much progress has been made in designing new donor and acceptor molecules, rational control over active layer morphology remains a central challenge. Long-term device stability is another important consideration that needs to be addressed. This review highlights supramolecular strategies for generating highly stable nanostructured organic photovoltaic active materials by design.

  1. Hydrogenated Amorphous Silicon Germanium Active Layer for Top Cell of a Multi Junction Cell Structure.

    PubMed

    Cho, Jaehyun; Iftiquar, S M; Kim, Minbum; Park, Jinjoo; Jung, Junhee; Kim, Jiwoong; Yi, Junsin

    2016-05-01

    Intrinsic hydrogenated amorphous silicon-germanium (a-SiGe:H) alloy is generally used in the bottom cell because of its low band gap. The a-SiGe:H has a higher photo conductivity in comparison to the a-Si:H; thus, it is expected that the a-SiGe:H can show better short circuit current density than that of the a-Si:H based solar cell. Therefore, we optimized a-SiGe:H active layer that can be a suitable choice for the front cell of a multi junction.solar cell. Furthermore, we carried out a comparative study of the solar cells that have a-SiGe:H and a-Si:H as respective active layers. The a-SiGe:H based solar cells show higher short circuit current density, while the a-Si:H based cells show higheropen circuit voltage. The current-voltage characteristics of these cells are as follows: (a) V(oc) = 770 mV, J(sc) = 15.0 mA/cm2, FF = 64.5%, and η = 7.47% for a-SiGe:H based cell; and (b) V(oc) = 826 mV, J(sc) = 13.63 mA/cm2, FF = 72.0%, and η = 8.1% for a-Si:H based cell.

  2. Mapping Active-Layer Thickness in an Urbanized Environment: The Barrow Urban Heat Island Study

    NASA Astrophysics Data System (ADS)

    Klene, A. E.; Hinkel, K. M.; Nelson, F. E.; Shiklomanov, N. I.

    2003-12-01

    Local and global changes in the Arctic climate may have profound impacts on hydrology, soil stability, and infrastructure, such as roads, buildings, and water, gas, or oil pipelines. These changes will be manifested in large part through permafrost, which can influence virtually all physical, chemical, and biological processes occurring in the soil. The "Barrow Urban Heat Island Study" (BUHIS) is an ongoing project in northern Alaska that examines the effects of urbanization on air and soil temperatures in and around Barrow. At 4600 residents, Barrow is the largest native settlement in the circumarctic region and the northernmost urban area in the United States. Initiated in summer 2001, BUHIS is recording temperature and thaw depth at more than 60 locations throughout the village, the developing suburbs, and surrounding undisturbed tundra. This paper describes one part of study examining the active layer and anthropogenic influences on its thickness. Summer air and soil temperature data, together with digital vegetation and soil maps, are used as input to a modified Stefan solution to map depth of thaw over an area of 100 square kilometers that includes both the village of Barrow and the surrounding tundra. Maps representing end-of-summer conditions for 2001 provide the first spatial/temporal representation of active-layer variability within an urbanized area. Increasing urban development in Arctic regions is causing information about changes accompanying industrial development and urbanization to become more vital, particularly given the possibility of a warming climate.

  3. Cooperation between adsorbates accounts for the activation of atomic layer deposition reactions.

    PubMed

    Shirazi, Mahdi; Elliott, Simon D

    2015-04-14

    Atomic layer deposition (ALD) is a technique for producing conformal layers of nanometre-scale thickness, used commercially in non-planar electronics and increasingly in other high-tech industries. ALD depends on self-limiting surface chemistry but the mechanistic reasons for this are not understood in detail. Here we demonstrate, by first-principle calculations of growth of HfO2 from Hf(N(CH3)2)4-H2O and HfCl4-H2O and growth of Al2O3 from Al(CH3)3-H2O, that, for all these precursors, co-adsorption plays an important role in ALD. By this we mean that previously-inert adsorbed fragments can become reactive once sufficient numbers of molecules adsorb in their neighbourhood during either precursor pulse. Through the calculated activation energies, this 'cooperative' mechanism is shown to have a profound influence on proton transfer and ligand desorption, which are crucial steps in the ALD cycle. Depletion of reactive species and increasing coordination cause these reactions to self-limit during one precursor pulse, but to be re-activated via the cooperative effect in the next pulse. This explains the self-limiting nature of ALD.

  4. Determinants of carbon release from the active layer and permafrost deposits on the Tibetan Plateau

    PubMed Central

    Chen, Leiyi; Liang, Junyi; Qin, Shuqi; Liu, Li; Fang, Kai; Xu, Yunping; Ding, Jinzhi; Li, Fei; Luo, Yiqi; Yang, Yuanhe

    2016-01-01

    The sign and magnitude of permafrost carbon (C)-climate feedback are highly uncertain due to the limited understanding of the decomposability of thawing permafrost and relevant mechanistic controls over C release. Here, by combining aerobic incubation with biomarker analysis and a three-pool model, we reveal that C quality (represented by a higher amount of fast cycling C but a lower amount of recalcitrant C compounds) and normalized CO2–C release in permafrost deposits were similar or even higher than those in the active layer, demonstrating a high vulnerability of C in Tibetan upland permafrost. We also illustrate that C quality exerts the most control over CO2–C release from the active layer, whereas soil microbial abundance is more directly associated with CO2–C release after permafrost thaw. Taken together, our findings highlight the importance of incorporating microbial properties into Earth System Models when predicting permafrost C dynamics under a changing environment. PMID:27703168

  5. Topology optimization of magnetorheological fluid layers in sandwich plates for semi-active vibration control

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaopeng; Kang, Zhan

    2015-08-01

    This paper investigates topology optimization of the magnetorheological (MR) fluid layer in a sandwich plate for improving the semi-active vibration control performance. Therein, a uniform magnetic field is applied across the MR fluid layer to provide a semi-active damping control effect. In the optimization model, the pseudo-densities describing the MR fluid material distribution are taken as design variables, and an artificial magneto-rheological fluid model (AMRF) with penalization is proposed to suppress intermediate density values. For reducing the vibration level under harmonic excitations, the dynamic compliance under a specific excitation frequency, or the frequency-aggregated dynamic compliance in a given frequency band, is taken as the objective function to be minimized. In this context, the adjoint-variable sensitivity analysis scheme is derived. The effectiveness and efficiency of the proposed method are demonstrated by numerical examples, in which the structural dynamic performance can be remarkably improved through optimization. The influences of several key factors on the optimal designs are also explored. It is shown that the AMRF model is effective in yielding clear boundaries in the final optimal solutions without use of additional regularization techniques.

  6. Blended Wing Body Systems Studies: Boundary Layer Ingestion Inlets With Active Flow Control

    NASA Technical Reports Server (NTRS)

    Geiselhart, Karl A. (Technical Monitor); Daggett, David L.; Kawai, Ron; Friedman, Doug

    2003-01-01

    A CFD analysis was performed on a Blended Wing Body (BWB) aircraft with advanced, turbofan engines analyzing various inlet configurations atop the aft end of the aircraft. The results are presented showing that the optimal design for best aircraft fuel efficiency would be a configuration with a partially buried engine, short offset diffuser using active flow control, and a D-shaped inlet duct that partially ingests the boundary layer air in flight. The CFD models showed that if active flow control technology can be satisfactorily developed, it might be able to control the inlet flow distortion to the engine fan face and reduce the powerplant performance losses to an acceptable level. The weight and surface area drag benefits of a partially submerged engine shows that it might offset the penalties of ingesting the low energy boundary layer air. The combined airplane performance of such a design might deliver approximately 5.5% better aircraft fuel efficiency over a conventionally designed, pod-mounted engine.

  7. Microtopographic and depth controls on active layer chemistry in Arctic polygonal ground

    DOE PAGES

    Newman, Brent D.; Throckmorton, Heather M.; Graham, David E.; Gu, Baohua; Hubbard, Susan S.; Liang, Liyuan; Wu, Yuxin; Heikoop, J. M.; Herndon, Elizabeth M.; Phelps, Tommy J.; et al

    2015-03-24

    Polygonal ground is a signature characteristic of Arctic lowlands, and carbon release from permafrost thaw can alter feedbacks to Arctic ecosystems and climate. This study describes the first comprehensive spatial examination of active layer biogeochemistry that extends across high- and low-centered, ice wedge polygons, their features, and with depth. Water chemistry measurements of 54 analytes were made on surface and active layer pore waters collected near Barrow, Alaska, USA. Significant differences were observed between high- and low-centered polygons suggesting that polygon types may be useful for landscape-scale geochemical classification. However, differences were found for polygon features (centers and troughs) formore » analytes that were not significant for polygon type, suggesting that finer-scale features affect biogeochemistry differently from polygon types. Depth variations were also significant, demonstrating important multidimensional aspects of polygonal ground biogeochemistry. These results have major implications for understanding how polygonal ground ecosystems function, and how they may respond to future change.« less

  8. Interplay of solvent additive concentration and active layer thickness on the performance of small molecule solar cells.

    PubMed

    Love, John A; Collins, Samuel D; Nagao, Ikuhiro; Mukherjee, Subhrangsu; Ade, Harald; Bazan, Guillermo C; Nguyen, Thuc-Quyen

    2014-11-19

    A relationship between solvent additive concentration and active layer thickness in small-molecule solar cells is investigated. Specifically, the additive concentration must scale with the amount of semiconductor material and not as absolute concentration in solution. Devices with a wide range of active layers with thickness up to 200 nm can readily achieve efficiencies close to 6% when the right concentration of additive is used.

  9. Threshold improvement in uniformly lying helix cholesteric liquid crystal laser using auxiliary π-conjugated polymer active layer

    NASA Astrophysics Data System (ADS)

    Yoshida, Hiroyuki; Shiozaki, Yusuke; Inoue, Yo; Takahashi, Masaya; Ogawa, Yasuhiro; Fujii, Akihiko; Ozaki, Masanori

    2013-05-01

    We propose a device structure to lower the lasing threshold of a uniformly lying helix cholesteric liquid crystal (ChLC) laser. We place a π-conjugated polymer active layer beneath the ChLC layer to provide auxiliary gain, and demonstrate an improvement in the lasing threshold by a factor of 2.3. We also perform finite difference time domain calculations coupled with rate equations for a four-level system, and clarify the effect of the additional active layer on both the photonic density of states and the inversion population density. Although the addition of an extra layer lowers the photonic density of states, the gain provided by the auxiliary layer is sufficient to overcome the losses and decrease the lasing threshold. Our concept is useful for obtaining high-performance ChLC lasers.

  10. Layer-by-layer evolution of structure, strain, and activity for the oxygen evolution reaction in graphene-templated Pt monolayers.

    PubMed

    Abdelhafiz, Ali; Vitale, Adam; Joiner, Corey; Vogel, Eric; Alamgir, Faisal M

    2015-03-25

    In this study, we explore the dimensional aspect of structure-driven surface properties of metal monolayers grown on a graphene/Au template. Here, surface limited redox replacement (SLRR) is used to provide precise layer-by-layer growth of Pt monolayers on graphene. We find that after a few iterations of SLRR, fully wetted 4-5 monolayer Pt films can be grown on graphene. Incorporating graphene at the Pt-Au interface modifies the growth mechanism, charge transfers, equilibrium interatomic distances, and associated strain of the synthesized Pt monolayers. We find that a single layer of sandwiched graphene is able to induce a 3.5% compressive strain on the Pt adlayer grown on it, and as a result, catalytic activity is increased due to a greater areal density of the Pt layers beyond face-centered-cubic close packing. At the same time, the sandwiched graphene does not obstruct vicinity effects of near-surface electron exchange between the substrate Au and adlayers Pt. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) techniques are used to examine charge mediation across the Pt-graphene-Au junction and the local atomic arrangement as a function of the Pt adlayer dimension. Cyclic voltammetry (CV) and the oxygen reduction reaction (ORR) are used as probes to examine the electrochemically active area of Pt monolayers and catalyst activity, respectively. Results show that the inserted graphene monolayer results in increased activity for the Pt due to a graphene-induced compressive strain, as well as a higher resistance against loss of the catalytically active Pt surface.

  11. Hypoxia Activates Calpains in the Nerve Fiber Layer of Monkey Retinal Explants

    PubMed Central

    Hirata, Masayuki; Shearer, Thomas R.; Azuma, Mitsuyoshi

    2015-01-01

    Purpose The vascular ischemic hypothesis attributes nerve damage in the retina to decreased blood flow in the ophthalmic artery, reduced oxygenation, and impaired axonal transport. Activation of calpain enzymes contributes to retinal cell death during hypoxia. However, we still do not know in which specific retinal layers calpains are activated. Thus, the purpose of the present study was to investigate where and when calpains are activated in an improved culture model of hypoxic monkey retina. Methods Monkey retinal explants were cultured on microporous membranes with the retinal ganglion cell (RGC) side facing up. Explants were incubated under hypoxic conditions, with or without additional reoxygenation. When it was used, the calpain inhibitor SNJ-1945 was maintained throughout the culture period. Immunohistochemistry and immunoblotting assays for α-spectrin, calpains 1 and 2, calpastatin, β-III tubulin, and γ-synuclein were performed with specific antibodies. Cell death was assessed by TUNEL staining. Results Under normoxic conditions, TUNEL-positive cells were minimal in our improved culture conditions. As early as 8 hours after hypoxia, the 150-kDa calpain-specific α-spectrin breakdown product appeared in the nerve fiber layer (NFL), where calpains 1 and 2 were localized. TUNEL-positive RGCs then increased at later time periods. The calpain inhibitor SNJ-1945 ameliorated changes induced by hypoxia or hypoxia/reoxygenation. Conclusions During hypoxia/reoxygenation in an improved, relevant monkey model, calpains were first activated in the NFL, followed by death of the parent RGCs. This observation suggest that calpain-induced degeneration of retinal nerve fibers may be an underlying mechanism for RGC death in hypoxic retinal neuropathies. PMID:26393472

  12. Morphological effects on the electrochemical performance of lithium-rich layered oxide cathodes, prepared by electrospinning technique, for lithium-ion battery applications

    SciTech Connect

    Min, Ji Won; Kalathil, Abdul Kareem; Yim, Chul Jin; Im, Won Bin

    2014-06-01

    Li-rich Li{sub 1.2}Ni{sub 0.17}Co{sub 0.17}Mn{sub 0.5}O{sub 2} cathode materials were synthesized by electrospinning technique with different polymers, and their structural, morphological, and electrochemical performances were investigated. It was found that the electrospinning process leads to the formation of a fiber and flower-like morphology, by using different polymers and heat treatment conditions. The nanostructured morphology provided these materials with high initial discharge capacity. The cycling stability was improved with agglomerated nano-particles, as compared with porous materials. - Highlights: • Fiber and flower-like Li-rich cathode was synthesized by simple electrospinning. • Polymer dependent morphology and electrochemical performance was investigated. • Well-organized porous structure facilitates the diffusion of lithium ions. • Technique could be applicable to other cathode materials as well.

  13. Actomyosin dynamics drive local membrane component organization in an in vitro active composite layer

    PubMed Central

    Husain, Kabir; Iljazi, Elda; Bhat, Abrar; Bieling, Peter; Mullins, R. Dyche; Rao, Madan; Mayor, Satyajit

    2016-01-01

    The surface of a living cell provides a platform for receptor signaling, protein sorting, transport, and endocytosis, whose regulation requires the local control of membrane organization. Previous work has revealed a role for dynamic actomyosin in membrane protein and lipid organization, suggesting that the cell surface behaves as an active composite composed of a fluid bilayer and a thin film of active actomyosin. We reconstitute an analogous system in vitro that consists of a fluid lipid bilayer coupled via membrane-associated actin-binding proteins to dynamic actin filaments and myosin motors. Upon complete consumption of ATP, this system settles into distinct phases of actin organization, namely bundled filaments, linked apolar asters, and a lattice of polar asters. These depend on actin concentration, filament length, and actin/myosin ratio. During formation of the polar aster phase, advection of the self-organizing actomyosin network drives transient clustering of actin-associated membrane components. Regeneration of ATP supports a constitutively remodeling actomyosin state, which in turn drives active fluctuations of coupled membrane components, resembling those observed at the cell surface. In a multicomponent membrane bilayer, this remodeling actomyosin layer contributes to changes in the extent and dynamics of phase-segregating domains. These results show how local membrane composition can be driven by active processes arising from actomyosin, highlighting the fundamental basis of the active composite model of the cell surface, and indicate its relevance to the study of membrane organization. PMID:26929326

  14. Identifying active functionalities on few-layered graphene catalysts for oxidative dehydrogenation of isobutane.

    PubMed

    Dathar, Gopi Krishna Phani; Tsai, Yu-Tung; Gierszal, Kamil; Xu, Ye; Liang, Chengdu; Rondinone, Adam J; Overbury, Steven H; Schwartz, Viviane

    2014-02-01

    The general consensus in the studies of nanostructured carbon catalysts for oxidative dehydrogenation (ODH) of alkanes to olefins is that the oxygen functionalities generated during synthesis and reaction are responsible for the catalytic activity of these nanostructured carbons. Identification of the highly active oxygen functionalities would enable engineering of nanocarbons for ODH of alkanes. Few-layered graphenes were used as model catalysts in experiments to synthesize reduced graphene oxide samples with varying oxygen concentrations, to characterize oxygen functionalities, and to measure the activation energies for ODH of isobutane. Periodic density functional theory calculations were performed on graphene nanoribbon models with a variety of oxygen functionalities at the edges to calculate their thermal stability and to model reaction mechanisms for ODH of isobutane. Comparing measured and calculated thermal stability and activation energies leads to the conclusion that dicarbonyls at the zigzag edges and quinones at armchair edges are appropriately balanced for high activity, relative to other model functionalities considered herein. In the ODH of isobutane, both dehydrogenation and regeneration of catalytic sites are relevant at the dicarbonyls, whereas regeneration is facile compared with dehydrogenation at quinones. The catalytic mechanism involves weakly adsorbed isobutane reducing functional oxygen and leaving as isobutene, and O2 in the feed, weakly adsorbed on the hydrogenated functionality, reacting with that hydrogen and regenerating the catalytic sites.

  15. Polyethylene/organically-modified layered-silicate nanocomposites with antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Songtipya, P.; Jimenez-Gasco, M. M.; Manias, E.

    2009-03-01

    Despite the very intensive research on polymer nanocomposites, the opportunities for new functionalities possible by nanofillers still remain largely untapped. Here, we present polyethylene/inorganic nanocomposites that exhibit strongly enhanced mechanical performance and, at the same time, also an antimicrobial activity originating from the organo-filler nature. Specifically, PE/organically-modified layered-silicate nanocomposites were prepared via melt-processing, and antimicrobial activity was designed by proper choice of their organic modification. Their antimicrobial activity was measured against three micotoxinogen fungal strains (Penicillium roqueforti and claviforme, and Fusarium graminearum) as model soil-borne plant and food contaminants. Montmorillonite-based organofillers, which only differ in their organic modification, were used to exemplify how these surfactants can be designed to render antifungal activity to the nanocomposites. The comparative discussion of the growth of fungi on unfilled PE and nanocomposite PE films is used to demonstrate how the antimicrobial efficacy is dictated by the surfactant chemistry and, further, how the nanocomposites' inhibitory activity compares to that of the organo-fillers and the surfactants.

  16. Active and Passive Galaxies at z ~ 2: Rest-frame Optical Morphologies with WFC3

    NASA Astrophysics Data System (ADS)

    Cameron, E.; Carollo, C. M.; Oesch, P. A.; Bouwens, R. J.; Illingworth, G. D.; Trenti, M.; Labbé, I.; Magee, D.

    2011-12-01

    We use the high angular resolution in the near-infrared of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope to determine YHVz color-color-selection criteria to identify and characterize 1.5 < z < 3.5 galaxies in the Hubble Ultra Deep Field 2009 (HUDF09) and Early Release Science (GOODS-South) fields. The WFC3 NIR images reveal galaxies at these redshifts that were undetected in the rest-frame UV HUDF/GOODS images, as well as true centers and regular disks in galaxies classified as highly irregular in rest-frame UV light. Across the 1.5 < z < 2.15 redshift range, regular disks are unveiled in the WFC3 images of ~25% of both intermediate and high mass galaxies, i.e., above 1010 M ⊙. Meanwhile, galaxies maintaining diffuse and/or irregular morphologies in the rest-frame optical light—i.e., not yet dynamically settled—at these epochs are almost entirely restricted to masses below 1011 M ⊙. In contrast at 2.25 < z < 3.5 these diffuse and/or irregular structures overwhelmingly dominate the morphological mix in both the intermediate and high mass regimes, while no regular disks, and only a small fraction (~25%) of smooth spheroids, are evident above 1011 M ⊙. Strikingly, by 1.5 < z < 2.25 roughly two out of every three galaxies at the highest masses are spheroids. In our small sample, the fraction of star-forming galaxies at these mass scales decreases concurrently from ~60% to ~5%. If confirmed, this indicates that z ~ 2 is the epoch of both the morphological transformation and quenching of star formation which assemble the first substantial population of massive ellipticals.

  17. Study on surface morphology and physicochemical properties of raw and activated South African coal and coal fly ash

    NASA Astrophysics Data System (ADS)

    Mishra, S. B.; Langwenya, S. P.; Mamba, B. B.; Balakrishnan, M.

    South African coal and coal fly ash were selected as the raw materials to be used for study of their morphology and physicochemical properties and their respective activated carbons for adsorption applications. Coal and fly ash were individually steam activated at a temperature range of 550-1000 °C for 1 h in a muffle furnace using cylindrical stainless steel containers. Scanning electron micrographs revealed a change in surface morphology with more mineral matter available on the surface of the coal particles due to increased devolatilization. However, in the case of fly ash, the macerals coalesced to form agglomerates and the presence of unburnt carbon constituted pores of diameter between 50 and 100 nm. The BET surface area of coal improved significantly from 5.31 to 52.12 m 2/g whereas in case of fly ash the surface area of the raw sample which was originally 0.59 m 2/g and upon activation increased only up to 2.04 m 2/g. The chemical composition of the fly ash confirmed that silica was the major component which was approximately 60% by weight fraction. The impact of this study was to highlight the importance of using raw materials such as coal and a waste product, in the form of coal ash, in order to produce affordable activated carbon that can be used in drinking water treatment. This would therefore ensure that the quality of water supplied to communities for drinking is not contaminated especially by toxic organic compounds.

  18. Ionization behavior, stoichiometry of association, and accessibility of functional groups in the active layers of reverse osmosis and nanofiltration membranes.

    PubMed

    Coronell, Orlando; González, Mari I; Mariñas, Benito J; Cahill, David G

    2010-09-01

    We characterized the fully aromatic polyamide (PA) active layers of six commercial reverse osmosis (RO) and nanofiltration (NF) membranes and found that in contrast to their similar elemental composition, total concentration of functional groups, and degree of polymerization, the ionization behavior and spatial distribution of carboxylic (R-COOH) groups within the active layers can be significantly different. We also studied the steric effects experienced by barium ion (Ba2+) in the active layers by determining the fraction of carboxylate (R-COO-) groups accessible to Ba2+; such fraction, referred to as the accessibility ratio (AR), was found to vary within the range AR=0.40-0.81, and to be generally independent of external solution pH. Additionally, we studied an NF membrane with a sulfonated polyethersulfone (SPES) active layer, and found that the concentration of sulfonate (R-SO3-) groups in the active layer was 1.67 M, independent of external solution pH and approximately three times higher than the maximum concentration (approximately 0.45+/-0.25 M) of R-COO- groups in PA active layers. The R-SO3- groups were found to be highly accessible to Ba2+ (AR=0.95+/-0.01).

  19. Contribution of Sp1 to Telomerase Expression and Activity in Skin Keratinocytes Cultured With a Feeder Layer.

    PubMed

    Bisson, Francis; Paquet, Claudie; Bourget, Jean-Michel; Zaniolo, Karine; Rochette, Patrick J; Landreville, Solange; Damour, Odile; Boudreau, François; Auger, François A; Guérin, Sylvain L; Germain, Lucie

    2015-02-01

    The growth of primary keratinocytes is improved by culturing them with a feeder layer. The aim of this study was to assess whether the feeder layer increases the lifespan of cultured epithelial cells by maintaining or improving telomerase activity and expression. The addition of an irradiated fibroblast feeder layer of either human or mouse origin (i3T3) helped maintain telomerase activity as well as expression of the transcription factor Sp1 in cultured keratinocytes. In contrast, senescence occurred earlier, together with a reduction of Sp1 expression and telomerase activity, in keratinocytes cultured without a feeder layer. Telomerase activity was consistently higher in keratinocytes grown on the three different feeder layers tested relative to cells grown without them. Suppression of Sp1 expression by RNA inhibition (RNAi) reduced both telomerase expression and activity in keratinocytes and also abolished their long-term growth capacity suggesting that Sp1 is a key regulator of both telomerase gene expression and cell cycle progression of primary cultured human skin keratinocytes. The results of the present study therefore suggest that the beneficial influence of the feeder layer relies on its ability to preserve telomerase activity in cultured human keratinocytes through the maintenance of stable levels of Sp1 expression.

  20. Contribution of Sp1 to Telomerase Expression and Activity in Skin Keratinocytes Cultured With a Feeder Layer.

    PubMed

    Bisson, Francis; Paquet, Claudie; Bourget, Jean-Michel; Zaniolo, Karine; Rochette, Patrick J; Landreville, Solange; Damour, Odile; Boudreau, François; Auger, François A; Guérin, Sylvain L; Germain, Lucie

    2015-02-01

    The growth of primary keratinocytes is improved by culturing them with a feeder layer. The aim of this study was to assess whether the feeder layer increases the lifespan of cultured epithelial cells by maintaining or improving telomerase activity and expression. The addition of an irradiated fibroblast feeder layer of either human or mouse origin (i3T3) helped maintain telomerase activity as well as expression of the transcription factor Sp1 in cultured keratinocytes. In contrast, senescence occurred earlier, together with a reduction of Sp1 expression and telomerase activity, in keratinocytes cultured without a feeder layer. Telomerase activity was consistently higher in keratinocytes grown on the three different feeder layers tested relative to cells grown without them. Suppression of Sp1 expression by RNA inhibition (RNAi) reduced both telomerase expression and activity in keratinocytes and also abolished their long-term growth capacity suggesting that Sp1 is a key regulator of both telomerase gene expression and cell cycle progression of primary cultured human skin keratinocytes. The results of the present study therefore suggest that the beneficial influence of the feeder layer relies on its ability to preserve telomerase activity in cultured human keratinocytes through the maintenance of stable levels of Sp1 expression. PMID:24962522

  1. Layer-specific entrainment of gamma-band neural activity by the alpha rhythm in monkey visual cortex

    PubMed Central

    Spaak, Eelke; Bonnefond, Mathilde; Maier, Alexander; Leopold, David A.; Jensen, Ole

    2012-01-01

    Summary While the mammalian neocortex has a clear laminar organization, layer-specific neuronal computations remain to be uncovered. Several studies suggest that gamma band activity in primary visual cortex (V1) is produced in granular and superficial layers and is associated with the processing of visual input [1–3]. Oscillatory alpha band activity in deeper layers has been proposed to modulate neuronal excitability associated with changes in arousal and cognitive factors [4–7]. To investigate the layer-specific interplay between these two phenomena, we characterized the coupling between alpha and gamma band activity of the local field potential (LFP) in V1 of the awake macaque. Using multicontact laminar electrodes to measure spontaneous signals simultaneously from all layers of V1, we found a robust coupling between alpha phase in the deeper layers and gamma amplitude in granular and superficial layers. Moreover, the power in the two frequency bands was anticorrelated. Taken together, these findings demonstrate robust inter-laminar cross-frequency coupling in the visual cortex, supporting the view that neuronal activity in the alpha frequency range phasically modulates processing in the cortical microcircuit in a top-down manner [7]. PMID:23159599

  2. Atomic Layer-by-Layer Deposition of Pt on Pd Nanocubes for Catalysts with Enhanced Activity and Durability toward Oxygen Reduction

    SciTech Connect

    Xie, Shuifen; Choi, Sang; Lu, Ning; Roling, Luke T.; Herron, Jeffrey A.; Zhang, Lei; Park, Jinho; Wang, Jinguo; Kim, Moon J.; Xie, Zhaoxiong; Mavrikakis, Manos; Xia, Younan

    2014-06-11

    An effective strategy for reducing the Pt content while retaining the activity of a Pt-based catalyst is to deposit the Pt atoms as ultrathin skins of only a few atomic layers thick on nanoscale substrates made of another metal. During deposition, however, the Pt atoms often take an island growth mode because of a strong bonding between Pt atoms. Here we report a versatile route to the conformal deposition of Pt as uniform, ultrathin shells on Pd nanocubes in a solution phase. The introduction of the Pt precursor at a relatively slow rate and high temperature allowed the deposited Pt atoms to spread across the entire surface of a Pd nanocube to generate a uniform shell. The thickness of the Pt shell could be controlled from one to six atomic layers by varying the amount of Pt precursor added into the system. Compared to a commercial Pt/C catalyst, the Pd@PnL (n = 1-6) core-shell nanocubes showed enhancements in specific activity and durability toward the oxygen reduction reaction (ORR). Density functional theory (DFT) calculations on model (100) surfaces suggest that the enhancement in specific activity can be attributed to the weakening of OH binding through ligand and strain effects, which, in turn, increases the rate of OH hydrogenation. A volcano-type relationship between the ORR specific activity and the number of Pt atomic layers was derived, in good agreement with the experimental results. Both theoretical and experimental studies indicate that the ORR specific activity was maximized for the catalysts based on Pd@Pt2-3L nanocubes. Because of the reduction in Pt content used and the enhancement in specific activity, the Pd@Pt1L nanocubes showed a Pt mass activity with almost three-fold enhancement relative to the Pt/C catalyst.

  3. Dendritic Polyglycerol Sulfate Inhibits Microglial Activation and Reduces Hippocampal CA1 Dendritic Spine Morphology Deficits.

    PubMed

    Maysinger, Dusica; Gröger, Dominic; Lake, Andrew; Licha, Kai; Weinhart, Marie; Chang, Philip K-Y; Mulvey, Rose; Haag, Rainer; McKinney, R Anne

    2015-09-14

    Hyperactivity of microglia and loss of functional circuitry is a common feature of many neurological disorders including those induced or exacerbated by inflammation. Herein, we investigate the response of microglia and changes in hippocampal dendritic postsynaptic spines by dendritic polyglycerol sulfate (dPGS) treatment. Mouse microglia and organotypic hippocampal slices were exposed to dPGS and an inflammogen (lipopolysaccharides). Measurements of intracellular fluorescence and confocal microscopic analyses revealed that dPGS is avidly internalized by microglia but not CA1 pyramidal neurons. Concentration and time-dependent response studies consistently showed no obvious toxicity of dPGS. The adverse effects induced by proinflammogen LPS exposure were reduced and dendritic spine morphology was normalized with the addition of dPGS. This was accompanied by a significant reduction in nitrite and proinflammatory cytokines (TNF-α and IL-6) from hyperactive microglia suggesting normalized circuitry function with dPGS treatment. Collectively, these results suggest that dPGS acts anti-inflammatory, inhibits inflammation-induced degenerative changes in microglia phenotype and rescues dendritic spine morphology. PMID:26218295

  4. Transformation of organic-inorganic hybrid films obtained by molecular layer deposition to photocatalytic layers with enhanced activity.

    PubMed

    Ishchuk, Sergey; Taffa, Dereje Hailu; Hazut, Ori; Kaynan, Niv; Yerushalmi, Roie

    2012-08-28

    We present the transformation of organic-inorganic hybrid titanicone films formed by TiCl(4) as metal precursor and ethylene glycol (EG) using solvent-free MLD to highly active photocatalytic films. The photocatalytic activities of the films were investigated using hydroxyl-functionalized porphyrin as a spectroscopic marker. TEM imaging and electron diffraction, XPS, UV-vis spectroscopy, and spectroscsopic ellipsometry were employed for structural and composition analyses of the films. The photocatalytic activity of Ti-EG films was investigated for different anneal temperatures and compared to TiO(2) films prepared by ALD using TiCl(4) as metal precursor and H(2)O (TiO(2) films). Overall, our results indicate that the photocatalytic activity of the thermally annealed Ti-EG film is about 5-fold increased compared to that of the TiO(2) film prepared by ALD for optimal process conditions. The combined results indicate that the structural and photocatalytic properties can be assigned to three states: (I) amorphous state, intermediate dye loading, low photocatalytic activity, (II) intermediate film state with both crystalline and amorphous regions, high dye loading, high catalytic activity, and (III) highly crystalline film with low dye loading and low photocatalytic activity. The formation of photocatalytic nanotubes (NTs) is demonstrated using sacrificial Ge nanowires (NWs) scaffolds to yield Ti-EG NT structures with controllable wall thickness structures and enhanced dye loading capacity. Our results demonstrate the feasibility and high potential of MLD to form metal oxides with high photocatalytic activity. PMID:22768917

  5. Successful childbirth after intracytoplasmic morphologically selected sperm injection without assisted oocyte activation in a patient with globozoospermia.

    PubMed

    Sermondade, N; Hafhouf, E; Dupont, C; Bechoua, S; Palacios, C; Eustache, F; Poncelet, C; Benzacken, B; Lévy, R; Sifer, C

    2011-11-01

    We here report a successful pregnancy and healthy childbirth obtained in a case of total globozoospermia after intracytoplasmic morphologically selected sperm injection (IMSI) without assisted oocyte activation (AOA). Two semen analyses showed 100% globozoospermia on classic spermocytogram. Motile sperm organelle morphology examination (MSOME) analysis at ×10,000 magnification confirmed the round-headed aspect for 100% of sperm cells, but 1% of the spermatozoa seemed to present a small bud of acrosome. This particular aspect was confirmed by transmission electron microscopy and anti-CD46 staining analysis. Results from sperm DNA fragmentation and fluorescence in situ hybridization analyses were normal. The karyotype was 46XY, and no mutations or deletions in SPATA16 and DPY19L2 genes were detected. Considering these results, a single IMSI cycle was performed, and spermatozoa were selected for the absence of vacuoles and the presence of a small bud of acrosome. A comparable fertilization rate with or without calcium-ionophore AOA was observed. Two fresh top-quality embryos obtained without AOA were transferred at Day 2 after IMSI, leading to pregnancy and birth of a healthy baby boy. This successful outcome suggests that MSOME may be useful in cases of globozoospermia in order to carefully evaluate sperm morphology and to maximize the benefit of ICSI/IMSI.

  6. Absorption of the selenite anion from aqueous solutions by thermally activated layered double hydroxide.

    PubMed

    Liu, Rui; Frost, Ray L; Martens, Wayde N

    2009-03-01

    The presence of selenite or selenate in potable water is a health hazard especially when consumed over a long period of time. Its removal from potable water is of importance. This paper reports technology for the removal of selenite from water through the use of thermally activated layered double hydroxides. Mg/Al hydrotalcites with selenite in the interlayer were prepared at different times from 0.5 to 20 h through ion exchange. X-ray diffraction of the MgAlSeO3 hydrotalcites indicates that the selenite anion entered the interlayer spacing of Mg/Al hydrotalcite and MgAlSeO3 hydrotalcite was formed. Raman spectra proved the presence of selenite anion in the hydrotalcite interlayer as the counter anion. The band intensity and width of MgAlSeO3 hydrotalcite in the region of 3800-3000 cm(-1) increase with the adsorption of selenite by the Mg/Al hydrotalcite. The characteristic bands of free selenite anions in the MgAlSeO3 hydrotalcites are located between the region between 850 and 800 cm(-1). The Raman spectra of the lower wave number region of 550-500 cm(-1) show a shift toward higher wave numbers with adsorption of the selenite. An estimation of the amount of selenite anion removed by the thermally activated layered double hydroxide was obtained through the measurement of the intensity of the selenite Raman bands at 814 and 835 cm(-1) resulting from the amount of selenite anion remaining in solution. Thermally activated LDHs provide a mechanism for removing selenite anions from aqueous solutions.

  7. An Integrated Observational and Model Synthesis Approach to Examine Dominant Environmental Controls on Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Atchley, A. L.; Coon, E.; Painter, S. L.; Harp, D. R.; Wilson, C. J.

    2015-12-01

    The active layer thickness (ALT) - the annual maximum depth of soil with above 0°C temperatures - in part determines the volume of carbon-rich stores available for decomposition and therefore potential greenhouse gas release into the atmosphere from Arctic tundra. However, understanding and predicting ALT in polygonal tundra landscapes is difficult due to the complex nature of hydrothermal atmospheric-surface-subsurface interactions in freezing/thawing soil. Simply deconvolving effects of single environmental controls on ALT is not possible with measurements alone as processes act in concert to drive thaw depth formation. Process-rich models of thermal hydrological dynamics, conversely, are a valuable tool for understanding the dominant controls and uncertainties in predicting permafrost conditions. By integrating observational data with known physical relationships to form process-rich models, synthetic experiments can then be used to explore a breadth of environmental conditions encountered and the effect of each environmental attribute may be assessed. Here a process rich thermal hydrology model, The Advanced Terrestrial Simulator, has been created and calibrated using observed data from Barrow, AK. An ensemble of 1D thermal hydrologic models were simulated that span a range of three environmental factors 1) thickness of organic rich soil, 2) snow depth, and 3) soil moisture content, to investigate the role of each factor on ALT. Results show that organic layer thickness acts as a strong insulator and is the dominant control of ALT, but the strength of the effect of organic layer thickness is also dependent on the saturation state. Using the ensemble results, the effect of peat thickness on ALT was then examined on a 2D domain. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and

  8. PEMFC catalyst layers: the role of micropores and mesopores on water sorption and fuel cell activity.

    PubMed

    Soboleva, Tatyana; Malek, Kourosh; Xie, Zhong; Navessin, Titichai; Holdcroft, Steven

    2011-06-01

    The effects of carbon microstructure and ionomer loading on water vapor sorption and retention in catalyst layers (CLs) of PEM fuel cells are investigated using dynamic vapor sorption. Catalyst layers based on Ketjen Black and Vulcan XC-72 carbon blacks, which possess distinctly different surface areas, pore volumes, and microporosities, are studied. It is found that pores <20 nm diameter facilitate water uptake by capillary condensation in the intermediate range of relative humidities. A broad pore size distribution (PSD) is found to enhance water retention in Ketjen Black-based CLs whereas the narrower mesoporous PSD of Vulcan CLs is shown to have an enhanced water repelling action. Water vapor sorption and retention properties of CLs are correlated to electrochemical properties and fuel cell performance. Water sorption enhances electrochemical properties such as the electrochemically active surface area (ESA), double layer capacitance and proton conductivity, particularly when the ionomer content is very low. The hydrophilic properties of a CL on the anode and the cathode are adjusted by choosing the PSD of carbon and the ionomer content. It is shown that a reduction of ionomer content on either cathode or anode of an MEA does not necessarily have a significant detrimental effect on the MEA performance compared to the standard 30 wt % ionomer MEA. Under operation in air and high relative humidity, a cathode with a narrow pore size distribution and low ionomer content is shown to be beneficial due to its low water retention properties. In dry operating conditions, adequate ionomer content on the cathode is crucial, whereas it can be reduced on the anode without a significant impact on fuel cell performance.

  9. Hepatic P450 enzyme activity, tissue morphology and histology of mink (Mustela vison) exposed to polychlorinated dibenzofurans.

    PubMed

    Moore, Jeremy N; Newsted, John L; Hecker, Markus; Zwiernik, Matthew J; Fitzgerald, Scott D; Kay, Denise P; Zhang, Xiaowei; Higley, Eric B; Aylward, Lesa L; Beckett, Kerrie J; Budinsky, Robert A; Bursian, Steven J; Giesy, John P

    2009-08-01

    Dose- and time-dependent effects of environmentally relevant concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ) of 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of these two congeners on hepatic P450 enzyme activity and tissue morphology, including jaw histology, of adult ranch mink were determined under controlled conditions. Adult female ranch mink were fed either TCDF (0.98, 3.8, or 20 ng TEQ(TCDF)/kg bw/day) or PeCDF (0.62, 2.2, or 9.5 ng TEQ(PeCDF)/kg bw/day), or a mixture of TCDF and PeCDF (4.1 ng TEQ(TCDF)/kg bw/day and 2.8 ng TEQ(PeCDF)/kg bw/day, respectively) for 180 days. Doses used in this study were approximately eight times greater than those reported in a parallel field study. Activities of the cytochrome P450 1A enzymes, ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-deethylase (MROD) were significantly greater in livers of mink exposed to TCDF, PeCDF, and a mixture of the two congeners; however, there were no significant histological or morphological effects observed. It was determined that EROD and MROD activity can be used as sensitive biomarkers of exposure to PeCDF and TCDF in adult female mink; however, under the conditions of this study, the response of EROD/MROD induction occurred at doses that were less than those required to cause histological or morphological changes. PMID:19458992

  10. Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes.

    PubMed

    Hultman, Jenni; Waldrop, Mark P; Mackelprang, Rachel; David, Maude M; McFarland, Jack; Blazewicz, Steven J; Harden, Jennifer; Turetsky, Merritt R; McGuire, A David; Shah, Manesh B; VerBerkmoes, Nathan C; Lee, Lang Ho; Mavrommatis, Kostas; Jansson, Janet K

    2015-05-14

    Over 20% of Earth's terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing, permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils and a rapid shift in functional gene composition during short-term thaw experiments. However, the fate of permafrost carbon depends on climatic, hydrological and microbial responses to thaw at decadal scales. Here we use the combination of several molecular 'omics' approaches to determine the phylogenetic composition of the microbial communities, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy reveals a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost. PMID:25739499

  11. Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes

    NASA Astrophysics Data System (ADS)

    Hultman, Jenni; Waldrop, Mark P.; Mackelprang, Rachel; David, Maude M.; McFarland, Jack; Blazewicz, Steven J.; Harden, Jennifer; Turetsky, Merritt R.; McGuire, A. David; Shah, Manesh B.; Verberkmoes, Nathan C.; Lee, Lang Ho; Mavrommatis, Kostas; Jansson, Janet K.

    2015-05-01

    Over 20% of Earth's terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing, permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils and a rapid shift in functional gene composition during short-term thaw experiments. However, the fate of permafrost carbon depends on climatic, hydrological and microbial responses to thaw at decadal scales. Here we use the combination of several molecular `omics' approaches to determine the phylogenetic composition of the microbial communities, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy reveals a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost.

  12. Multi-omics of Permafrost, Active Layer and Thermokarst Bog Soil Microbiomes

    SciTech Connect

    Hultman, Jenni; Waldrop, Mark P.; Mackelprang, Rachel; David, Maude; McFarland, Jack; Blazewicz, Steven J.; Harden, Jennifer W.; Turetsky, Merritt; McGuire, A. David; Shah, Manesh B.; VerBerkmoes, Nathan C.; Lee, Lang Ho; Mavrommatis, Konstantinos; Jansson, Janet K.

    2015-03-04

    Over 20% of Earth’s terrestrial surface is underlain by permafrost with vast stores of carbon that, if thawed may represent the largest future transfer of C from the biosphere to the atmosphere 1. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils 2-4 and a rapid shift in functional gene composition during short-term thaw experiments 3. However, the fate of permafrost C depends on climatic, hydrologic, and microbial responses to thaw at decadal scales 5, 6. Here the combination of several molecular “omics” approaches enabled us to determine the phylogenetic composition of the microbial community, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy revealed a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost.

  13. Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes.

    PubMed

    Hultman, Jenni; Waldrop, Mark P; Mackelprang, Rachel; David, Maude M; McFarland, Jack; Blazewicz, Steven J; Harden, Jennifer; Turetsky, Merritt R; McGuire, A David; Shah, Manesh B; VerBerkmoes, Nathan C; Lee, Lang Ho; Mavrommatis, Kostas; Jansson, Janet K

    2015-05-14

    Over 20% of Earth's terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing, permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils and a rapid shift in functional gene composition during short-term thaw experiments. However, the fate of permafrost carbon depends on climatic, hydrological and microbial responses to thaw at decadal scales. Here we use the combination of several molecular 'omics' approaches to determine the phylogenetic composition of the microbial communities, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy reveals a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost.

  14. Particle size distribution and morphological changes in activated carbon-metal oxide hybrid catalysts prepared under different heating conditions.

    PubMed

    Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Gómez-Serrano, V

    2016-03-01

    In catalysis processes, activated carbon (AC) and metal oxides (MOs) are widely used either as catalysts or as catalyst supports because of their unique properties. A combination of AC and a MO in a single hybrid material entails changes not only in the composition, microstructure and texture but also in the morphology, which may largely influence the catalytic behaviour of the resulting product. This work is aimed at investigating the modifications in the morphology and particle size distribution (PSD) for AC-MO hybrid catalysts as a result of their preparation under markedly different heating conditions. From a commercial AC and six MO (Al2O3, Fe2O3, ZnO, SnO2, TiO2 and WO3) precursors, two series of such catalysts are prepared by wet impregnation, oven-drying at 120 ºC, and subsequent heat treatment at 200 ºC or 850 ºC in inert atmosphere. The resulting samples are characterized in terms of their morphology and PSD by scanning electron microscopy and ImageJ processing program. Obtained results indicate that the morphology, PSD and degree of dispersion of the supported catalysts are strongly dependent both on the MO precursor and the heat treatment temperature. With the temperature rise, trends are towards the improvement of crystallinity, the broadening of the PSD and the increase in the average particle size, thus suggesting the involvement of sintering mechanisms. Such effects are more pronounced for the Fe, Sn and W catalysts due to the reduction of the corresponding MOs by AC during the heat treatment at 850 ºC.

  15. SB203580 promotes EGF-stimulated early morphological differentiation in PC12 cell through activating ERK pathway.

    PubMed

    New, L; Li, Y; Ge, B; Zhong, H; Mansbridge, J; Liu, K; Han, J

    2001-01-01

    MAP kinases have important role in PC12 cell differentiation, since the activities of both extracellular regulated protein kinase (ERK) and p38 have been indicated as necessary signal for PC12 cell differentiation. Epidermal growth factor (EGF) and NGF both activate ERK and p38 in PC12 cells, but only NGF trigger differentiation. It has been proposed that the duration of ERK activation determines the switch from proliferation to differentiation, since EGF causes more transient activation of ERK than NGF in PC12 cells. Here we report that treatment of PC12 cells with EGF in the presence of SB203580, a widely used p38 inhibitor, caused differentiation. The pro-differentiation effect of SB203580 in EGF-treated PC12 cells was found to be independent of its function of p38 inhibition but was through an effect on the ERK pathway that has been recently reported (Kalmes et al. [1999] FEBS Lett. 444: 71-74; Hall-Jackson et al. [1999] Onc. 18: 2047-2054). We found that SB203580 by itself did not affect the activity of ERK1/2 but significantly extended EGF-induced ERK activation in PC12 cells, which resulted in early morphological differentiation. Our data indicated that although both ERK and p38 are required for PC12 cell differentiation, activation of p38 is not required when ERK is superactivated. Our data provided further evidence for the threshold theory that differentiation is determined by the duration of ERK activation.

  16. Geochemical drivers of organic matter decomposition in the active layer of Arctic tundra

    NASA Astrophysics Data System (ADS)

    Herndon, E.; Roy Chowdhury, T.; Mann, B.; Graham, D. E.; Wullschleger, S. D.; Gu, B.; Liang, L.

    2014-12-01

    Arctic tundra soils store large quantities of organic carbon that are susceptible to decomposition and release to the atmosphere as CO2 and CH4. Decomposition rates are limited by cold temperatures and widespread anoxia; however, ongoing changes in soil temperature, thaw depth, and water saturation are expected to influence rates and pathways of organic matter decomposition. In order to predict greenhouse gas releases from high-latitude ecosystems, it is necessary to identify how geochemical factors (e.g. terminal electron acceptors, carbon substrates) influence CO2 and CH4 production in tundra soils. This study evaluates spatial patterns of aqueous geochemistry in the active layer of low- to high-centered polygons located at the Barrow Environmental Observatory in northern Alaska. Pore waters from saturated soils were low in sulfate and nitrate but contained abundant Fe which may serve a major terminal electron acceptor for anaerobic microbial metabolism. Relatively high concentrations of soluble Fe accumulated in the middle of the active layer near the boundary between the organic and mineral horizon, and we infer that Fe-oxide reduction and dissolution in the mineral horizon produced soluble Fe that diffused upwards and was stabilized by complexation with dissolved organic matter. Fe concentrations in the bulk soil were higher in organic than mineral horizons due to the presence of these organic-Fe complexes and Fe-oxide precipitates. Dissolved CH4 increased with increasing proportions of dissolved Fe(III) in saturated soils from transitional and low-centered polygons. The opposite trend was observed in drier soils from flat- and high-centered polygons where deeper oxidation fronts may inhibit methanogenesis. Using multiple spectroscopic and molecular methods (e.g. UV-Vis, Fourier transform infrared, ultrahigh resolution mass spectrometry), we also observed that pore waters from the middle of the active layer contained more aromatic organics than in mineral

  17. Preparation and efficient visible light-induced photocatalytic activity of m-BiVO4 with different morphologies

    NASA Astrophysics Data System (ADS)

    Lu, Yanjie; Shang, Huishan; Shi, Fengjuan; Chao, Cong; Zhang, Xiang; Zhang, Bing

    2015-10-01

    The monoclinic scheelite BiVO4 crystals with peanut-like, oval, twin-quadrangle and twin-four-pointed star morphologies were synthesized via a facile one step hydrothermal method by using sodium citrate as the chelating agent. The X-ray diffraction and scanning electron microscopy were employed to elucidate the structures and mophologies of the as-prepared BiVO4 samples. The results showed that the formation of m-BiVO4 with different morphologies relied on the pH value of the precursor solution. The band gaps values (Eg) of all the BiVO4 samples were around 2.37-2.45 eV according to the UV-vis diffuse reflectance spectrum, which indicated that samples could strongly absorb in the visible light region. The photocatalytic activities of BiVO4 crystals were evaluated by degradation of MB in aqueous solution under artificial solar-light. The BiVO4 samples obtained at different pH values showed different photocatalytic activities during the sunlight-driven photodegradation of methylene blue (MB). The sample with peanut-like-shape prepared at pH=1 exhibited the highest activity, and the photocatalytic conversion could reach above 90% after 3 h of irradiation. The result suggested that m-BiVO4 with peanut-like-shape could be used as an effective photocatalyst in practical application for organic pollutants degradation.

  18. Gamma radiation affects active electrolyte transport by rabbit ileum. II. Correlation of alanine and theophylline response with morphology

    SciTech Connect

    Gunter-Smith, P.J.

    1989-03-01

    The response of ileal segments isolated from rabbits to an actively transported amino acid and a secretagogue was evaluated following exposure to 10 Gy whole-body gamma irradiation. The ability of ileal segments to respond to the actively transported amino acid, alanine, was not significantly diminished until 96 h postexposure. Decreased responsiveness to the secretagogue, theophylline, occurred earlier at 72 h. These effects did not appear to be accounted for by decreased food intake of irradiated animals alone. Examination of intestinal morphological changes with respect to these changes in electrolyte transport revealed that decreased amino acid transport coincides with loss of intestinal villi. Although a morphological correlate of decreased secretory response was not as striking as that for absorption, the theophylline response appeared to decline concomitant with the appearance of increased mitotic activity in the intestinal crypts. The results of this study indicate that, following a dose of 10 Gy, the inability of these tissues to respond to amino acids is due to a loss of mature villus absorptive cells subsequent to denudation of the intestinal mucosa. There appeared to be little impairment of cell membrane transport processes for alanine. In contrast, the decreased secretory response could not be correlated with the disappearance of any one cell type and perhaps results from increased proliferation in the crypts at the expense of differentiation.

  19. Gamma-radiation affects active electrolyte transport by rabbit ileum. 2. Correlation of alanine and theophylline response with morphology

    SciTech Connect

    Gunter-Smith, P.J.

    1989-01-01

    The response of ileal segments isolated from rabbits to an actively transported amino acid and a secretagogue was evaluated following exposure to 10-Gy whole-body gamma irradiation. The ability of ileal segments to respond to the actively transported amino acid, alanine, was not significantly diminished until 96 h postexposure. Decreased responsiveness to the secretagogue, theophylline, occurred earlier at 72 h. These effects did not appear to be accounted for by decreased food intake of irradiated animals alone. Examination of intestinal morphological changes with respect to these changes in electrolyte transport revealed that decreased amino acid transport coincides with loss of intestinal villi. Although a morphological correlate of decreased secretory response was not as striking as that for absorption, the theophylline response appeared to decline concomitant with the appearance of increased mitotic activity in the intestinal crypts. The result of this study indicate that, following a dose of 10 Gy, the inability of these tissues to respond to amino acids is due to a loss of mature villus absorptive cells subsequent to denudation of the intestinal mucosa. There appeared to be little impairment of cell membrane transport processes for alanine. In contrast, the decreased secretory response could not be correlated with the disappearance of any one cell type and perhaps results from increased proliferation in the crypts at the expense of differentiation.

  20. Effect of synthesis temperature on the morphology, structure and photocatalytic activity of TiO{sub 2} nanocrystals

    SciTech Connect

    Nayak, J. Mohapatra, A. K.; Kim, Heeje

    2015-06-24

    Nanocrystals of TiO{sub 2} were synthesized by a single-step chemical reaction between oleic acid and titanium (IV) iso-propoxide. The morphology and structure of the crystals were studied by X-ray diffraction and transmission electron microscopy. The vibrational properties of the nanocrystals were studied by Raman spectroscopy. The ultraviolet photocatalytic activity of the TiO{sub 2} nanocrystals was investigated by studying the photodegradation of aqueous solution of protocatecheuic acid (3,4-dihydroxy benzoic acid)

  1. Low-noise encoding of active touch by layer 4 in the somatosensory cortex

    PubMed Central

    Andrew Hires, Samuel; Gutnisky, Diego A; Yu, Jianing; O'Connor, Daniel H; Svoboda, Karel

    2015-01-01

    Cortical spike trains often appear noisy, with the timing and number of spikes varying across repetitions of stimuli. Spiking variability can arise from internal (behavioral state, unreliable neurons, or chaotic dynamics in neural circuits) and external (uncontrolled behavior or sensory stimuli) sources. The amount of irreducible internal noise in spike trains, an important constraint on models of cortical networks, has been difficult to estimate, since behavior and brain state must be precisely controlled or tracked. We recorded from excitatory barrel cortex neurons in layer 4 during active behavior, where mice control tactile input through learned whisker movements. Touch was the dominant sensorimotor feature, with >70% spikes occurring in millisecond timescale epochs after touch onset. The variance of touch responses was smaller than expected from Poisson processes, often reaching the theoretical minimum. Layer 4 spike trains thus reflect the millisecond-timescale structure of tactile input with little noise. DOI: http://dx.doi.org/10.7554/eLife.06619.001 PMID:26245232

  2. Vibration and damping characteristics of cylindrical shells with active constrained layer damping treatments

    NASA Astrophysics Data System (ADS)

    Zheng, Ling; Zhang, Dongdong; Wang, Yi

    2011-02-01

    In this paper, the application of active constrained layer damping (ACLD) treatments is extended to the vibration control of cylindrical shells. The governing equation of motion of cylindrical shells partially treated with ACLD treatments is derived on the basis of the constitutive equations of elastic, piezoelectric and visco-elastic materials and an energy approach. The damping of a visco-elastic layer is modeled by the complex modulus formula. A finite element model is developed to describe and predict the vibration characteristics of cylindrical shells partially treated with ACLD treatments. A closed-loop control system based on proportional and derivative feedback of the sensor voltage generated by the piezo-sensor of the ACLD patches is established. The dynamic behaviors of cylindrical shells with ACLD treatments such as natural frequencies, loss factors and responses in the frequency domain are further investigated. The effects of several key parameters such as control gains, location and coverage of ACLD treatments on vibration suppression of cylindrical shells are also discussed. The numerical results indicate the validity of the finite element model and the control strategy approach. The potential of ACLD treatments in controlling vibration and sound radiation of cylindrical shells used as major critical structures such as cabins of aircraft, hulls of submarines and bodies of rockets and missiles is thus demonstrated.

  3. Influence of quaternization of ammonium on antibacterial activity and cytocompatibility of thin copolymer layers on titanium.

    PubMed

    Waßmann, Marco; Winkel, Andreas; Haak, Katharina; Dempwolf, Wibke; Stiesch, Meike; Menzel, Henning

    2016-10-01

    Antimicrobial coatings are able to improve the osseointegration of dental implants. Copolymers are promising materials for such applications due to their combined properties of two different monomers. To investigate the influence of different monomer mixtures, we have been synthesized copolymers of dimethyl (methacryloxyethyl) phosphonate (DMMEP) and dipicolyl aminoethyl methacrylate in different compositions and have them characterized to obtain the r-parameters. Some of the copolymers with different compositions have also been alkylated with 1-bromohexane, resulting in quaternized ammonium groups. The copolymers have been deposited onto titanium surfaces resulting in ultrathin, covalently bound layers. These layers have been characterized by water contact angle measurements and ellipsometry. The influence of quaternary ammonium groups on antibacterial properties and cytocompatibility was studied: Activity against bacteria was tested with a gram positive Staphylococcus aureus strain. Cytocompatibility was tested with a modified LDH assay after 24 and 72 h to investigate adhesion and proliferation of human fibroblast cells on modified surfaces. The copolymer with the highest content of DMMEP showed a good reduction of S. aureus and in the alkylated version a very good reduction of about 95%. On the other hand, poor cytocompatibility is observed. However, our results show that this trend cannot be generalized for this copolymer system.

  4. Comparison of Plasma Activation of Thin Water Layers by Direct and Remote Plasma Sources

    NASA Astrophysics Data System (ADS)

    Kushner, Mark

    2014-10-01

    Plasma activation of liquids is now being investigated for a variety of biomedical applications. The plasma sources used for this activation can be generally classified as direct (the plasma is in contact with the surface of the liquid) or remote (the plasma does not directly touch the liquid). The direct plasma source may be a dielectric barrier discharge (DBD) where the surface of the liquid is a floating electrode or a plasma jet in which the ionization wave forming the plasma plume reaches the liquid. The remote plasma source may be a DBD with electrodes electrically isolated from the liquid or a plasma jet in which the ionization wave in the plume does not reach the liquid. In this paper, a comparison of activation of thin water layers on top of tissue, as might be encountered in wound healing, will be discussed using results from numerical investigations. We used the modeling platform nonPDPSIM to simulate direct plasma activation of thin water layers using DBDs and remote activation using plasma jets using up to hundreds of pulses. The DBDs are sustained in humid air while the plasma jets consist of He/O2 mixtures flowed into humid air. For similar number of pulses and energy deposition, the direct DBD plasma sources produce more acidification and higher production of nitrates/nitrites in the liquid. This is due to the accumulation of NxOy plasma jets, the convective flow removes many of these species prior to their diffusing into the water or reacting to form higher nitrogen oxides. This latter effect is sensitive to the repetition rate which determines whether reactive species formed during prior pulses overlap with newly produced reactive species. in the gas phase. In the plasma jets, the convective flow removes many of these species prior to their diffusing into the water or reacting to form higher nitrogen oxides. This latter effect is sensitive to the repetition rate which determines whether reactive species formed during prior pulses overlap with

  5. Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

    PubMed

    Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

    2016-05-24

    Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems. PMID:27124717

  6. Some enzyme activities associated with the chlorophyll containing layers of the immature barley pericarp.

    PubMed

    Duffus, C M; Rosie, R

    1973-09-01

    Some photosynthetic and biochemical properties of the chlorophyl containing layers of the pericarp of developing barley have been investigated. The tissue changes from pale green to bright green early in development, chlorophyll disappearing only at the later stages of maturity. It contains chloroplasts and probably amyloplasts and starch bearing chloroplasts. It is capable of high rates of light dependent oxygen evolution. It has been shown that the enzyme phosphoenol pyruvate carboxylase (EC 4.1.1.31) is present in the pericarp and is 100 times as active in carbon dioxide fixation as ribulose diphosphate carboxylase (EC 4.1.1.39). Other enzymes present in the pericarp are phosphoenol pyruvate synthetase, pyrophosphatase (EC 3.6.1.1), malate NAD and NADP dehydrogenases (EC 1.1.1.37), malic enzyme (EC 1.1.1.40), and fructose 1,6 diphosphatase (EC 3.1.3.11). PMID:24458756

  7. Influences and interactions of inundation, peat, and snow on active layer thickness: Modeling Archive

    DOE Data Explorer

    Scott Painter; Ethan Coon; Cathy Wilson; Dylan Harp; Adam Atchley

    2016-04-21

    This Modeling Archive is in support of an NGEE Arctic publication currently in review [4/2016]. The Advanced Terrestrial Simulator (ATS) was used to simulate thermal hydrological conditions across varied environmental conditions for an ensemble of 1D models of Arctic permafrost. The thickness of organic soil is varied from 2 to 40cm, snow depth is varied from approximately 0 to 1.2 meters, water table depth was varied from -51cm below the soil surface to 31 cm above the soil surface. A total of 15,960 ensemble members are included. Data produced includes the third and fourth simulation year: active layer thickness, time of deepest thaw depth, temperature of the unfrozen soil, and unfrozen liquid saturation, for each ensemble member. Input files used to run the ensemble are also included.

  8. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.

    PubMed

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

    2013-05-28

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

  9. Modeling of the polymer solar cell with a P3HT:PCBM active layer

    NASA Astrophysics Data System (ADS)

    Jelić, Ž.; Petrović, J.; Matavulj, P.; Melancon, J.; Sharma, A.; Zellhofer, C.; Živanović, S.

    2014-09-01

    In this paper we present a theoretical model for simulating the behavior of a polymer solar cell with a poly(3-hexylthiophene):1-(3-methoxycarbonyl) propyl-1-phenyl-[6, 6]-methanofullerene (P3HT:PCBM) active layer. Two different types of boundary conditions were considered, Dirichlet’s and mixed. For Dirichlet’s boundary conditions we have achieved an excellent agreement with the experiment. The influence of boundary conditions on the appearance of the s-shaped current-voltage characteristic (sometimes observed in experiments) has been investigated. When mixed boundary conditions are applied, calculated current-voltage characteristics are inevitably s-shaped. By altering the boundary carrier concentration, an s-shaped deformation in current-voltage characteristics is numerically simulated by using Dirichlet’s boundary conditions.

  10. Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

    PubMed

    Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

    2016-05-24

    Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems.

  11. Materials for the active layer of organic photovoltaics: ternary solar cell approach.

    PubMed

    Chen, Yung-Chung; Hsu, Chih-Yu; Lin, Ryan Yeh-Yung; Ho, Kuo-Chuan; Lin, Jiann T

    2013-01-01

    Power conversion efficiencies in excess of 7% have been achieved with bulk heterojunction (BHJ)-type organic solar cells using two components: p- and n-doped materials. The energy level and absorption profile of the active layer can be tuned by introduction of an additional component. Careful design of the additional component is required to achieve optimal panchromatic absorption, suitable energy-level offset, balanced electron and hole mobility, and good light-harvesting efficiency. This article reviews the recent progress on ternary organic photovoltaic systems, including polymer/small molecule/functional fullerene, polymer/polymer/functional fullerene, small molecule/small molecule/functional fullerene, polymer/functional fullerene I/functional fullerene II, and polymer/quantum dot or metal/functional fullerene systems.

  12. Reduction of Free Edge Peeling Stress of Laminated Composites Using Active Piezoelectric Layers

    PubMed Central

    Huang, Bin; Kim, Heung Soo

    2014-01-01

    An analytical approach is proposed in the reduction of free edge peeling stresses of laminated composites using active piezoelectric layers. The approach is the extended Kantorovich method which is an iterative method. Multiterms of trial function are employed and governing equations are derived by taking the principle of complementary virtual work. The solutions are obtained by solving a generalized eigenvalue problem. By this approach, the stresses automatically satisfy not only the traction-free boundary conditions, but also the free edge boundary conditions. Through the iteration processes, the free edge stresses converge very quickly. It is found that the peeling stresses generated by mechanical loadings are significantly reduced by applying a proper electric field to the piezoelectric actuators. PMID:25025088

  13. Influence of Plant Communities on Active Layer Depth in Boreal Forest

    NASA Astrophysics Data System (ADS)

    Fisher, James; Estop Aragones, Cristian; Thierry, Aaron; Hartley, Iain; Murton, Julian; Charman, Dan; Williams, Mathew; Phoenix, Gareth

    2015-04-01

    Vegetation plays a crucial role in determining active layer depth (ALD) and hence the extent to which permafrost may thaw under climate change. Such influences are multifaceted and include, for example, promotion of shallow ALD by insulation from moss or shading by plant canopies in summer, or trapping of snow in evergreen tree canopies that reduces snow insulation of soil in winter. However, while the role of different vegetation components are understood at a conceptual level, quantitative understanding of the relative importance of different vegetation components and how they interact to determine active layer depth is lacking. In addition, major abiotic factors such as fire and soil hydrological properties will considerably influence the role of vegetation in mediating ALD, though again this is not well understood. To address this we surveyed 60 plots across 4 sites of contrasting vegetation and fire status, encompassing a range of soil moisture and organic matter thickness, in the discontinuous permafrost zone near Yellowknife, NT, Canada. In each plot we measured ALD and a range of vegetation and soil parameters to understand how key characteristics of the understory and canopy vegetation, and soil properties influence ALD. Measurements included moss depth, tree canopy LAI, understory LAI, understory height, vegetation composition, soil organic matter depth, slope and soil moisture. By undertaking these surveys in sites with contrasting hydrological conditions in both burned and unburned areas we have also been able to determine which characteristics of the vegetation and soil are important for protecting permafrost, which characteristics emerge as the most important factors across sites (i.e. irrespective of site conditions) and which factors have site (ecosystem) specific influences. This work provides a major insight into how ecosystem properties influence ALD and therefore also how changes in ecosystems properties arising from climate change may influence

  14. Influence of Plant Communities on Active Layer Depth in Boreal Forest

    NASA Astrophysics Data System (ADS)

    Phoenix, G. K.; Fisher, J. P.; Estop-Aragones, C.; Thierry, A.; Hartley, I. P.; Murton, J.; Charman, D.; Williams, M.

    2014-12-01

    Vegetation plays a crucial role in determining active layer depth (ALD) and hence also the extent that permafrost may thaw under climate change. Such influences are multifaceted and include, for example, promotion of shallow ALD by insulation from moss or shading by plant canopies in summer, or trapping of snow in evergreen tree canopies that reduces snow insulation of soil in winter. However, while the role of different vegetation components are understood at a conceptual level, quantitative understanding of the relative importance of different vegetation components and how they interact to determine active layer depth is lacking. In addition, major abiotic factors such as fire and soil hydrological properties will considerably influence the role of vegetation in mediating ALD, though again this is not well understood. To address this we surveyed multiple plots across 4 sites of contrasting vegetation and fire status, including a range of soil moisture and organic matter thickness, in the discontinuous permafrost zone near Yellowknife, NT, Canada. In each plot we measured ALD and a range of vegetation and soil parameters to understand how key characteristics of the understory and canopy vegetation, and soil properties influence ALD. Measurements included moss depth, tree canopy LAI, understory LAI, understory height, vegetation composition, soil organic matter depth, slope and soil moisture. By undertaking these surveys in sites with contrasting hydrological conditions in both burned and unburned areas we have also been able to determine which characteristics of the vegetation and soil are important for protecting permafrost, which characteristics emerge as the most important factors across sites (i.e. irrespective of site conditions) and which factors have site (ecosystem) specific influences. This work provides a major insight into how ecosystem properties influence ALD and therefore also how changes in ecosystems properties arising from climate change may

  15. Many-body microhydrodynamics of colloidal particles with active boundary layers

    NASA Astrophysics Data System (ADS)

    Singh, Rajesh; Ghose, Somdeb; Adhikari, R.

    2015-06-01

    Colloidal particles with active boundary layers—regions surrounding the particles where non-equilibrium processes produce large velocity gradients—are common in many physical, chemical and biological contexts. The velocity or stress at the edge of the boundary layer determines the exterior fluid flow and, hence, the many-body interparticle hydrodynamic interaction. Here, we present a method to compute the many-body hydrodynamic interaction between N spherical active particles induced by their exterior microhydrodynamic flow. First, we use a boundary integral representation of the Stokes equation to eliminate bulk fluid degrees of freedom. Then, we expand the boundary velocities and tractions of the integral representation in an infinite-dimensional basis of tensorial spherical harmonics and, on enforcing boundary conditions in a weak sense on the surface of each particle, obtain a system of linear algebraic equations for the unknown expansion coefficients. The truncation of the infinite series, fixed by the degree of accuracy required, yields a finite linear system that can be solved accurately and efficiently by iterative methods. The solution linearly relates the unknown rigid body motion to the known values of the expansion coefficients, motivating the introduction of propulsion matrices. These matrices completely characterize hydrodynamic interactions in active suspensions just as mobility matrices completely characterize hydrodynamic interactions in passive suspensions. The reduction in the dimensionality of the problem, from a three-dimensional partial differential equation to a two-dimensional integral equation, allows for dynamic simulations of hundreds of thousands of active particles on multi-core computational architectures. In our simulation of 104 active colloidal particle in a harmonic trap, we find that the necessary and sufficient ingredients to obtain steady-state convective currents, the so-called ‘self-assembled pump’, are (a) one

  16. Morphology and optical properties of aluminum oxide formed into oxalic electrolyte with addition surface active agents

    NASA Astrophysics Data System (ADS)

    Kazarkin, B.; Stsiapanau, A.; Zhilinski, V.; Chernik, A.; Bezborodov, V.; Kozak, G.; Danilovich, S.; Smirnov, A.

    2016-08-01

    The article discusses the results of investigations of porous films of alumina, formed into oxalic electrolyte with addition surface active agents, in particular, ordering structure, roughness of a surface, the optical transparency of the electrolyte concentration and surface active agents. Also discusses the features of the formation of porous films of temperature and IR radiation.

  17. Favism: effect of divicine on rat erythrocyte sulfhydryl status, hexose monophosphate shunt activity, morphology, and membrane skeletal proteins.

    PubMed

    McMillan, D C; Bolchoz, L J; Jollow, D J

    2001-08-01

    Favism is an acute anemic crisis that can occur in susceptible individuals who ingest fava beans. The fava bean pyrimidine aglycone divicine has been identified as a hemotoxic constituent; however, its mechanism of toxicity remains unknown. We have shown recently that divicine can induce a favic-like response in rats and that divicine is directly toxic to rat red cells. In the present study, we have examined the effect of hemotoxic concentrations of divicine on rat erythrocyte sulfhydryl status, hexose monophosphate (HMP) shunt activity, morphology, and membrane skeletal proteins. In vitro exposure of rat red cells to divicine markedly stimulated HMP shunt activity and resulted in depletion of reduced glutathione with concomitant formation of glutathione-protein mixed-disulfides. Examination of divicine-treated red cells by scanning electron microscopy revealed transformation of the cells to an extreme echinocytic morphology. SDS-PAGE and immunoblotting analysis of the membrane skeletal proteins indicated that hemotoxicity was associated with the apparent loss of skeletal protein bands 2.1, 3, and 4.2, and the appearance of membrane-bound hemoglobin. Treatment of divicine-damaged red cells with dithiothreitol reversed the protein changes, which indicated that the observed alterations were due primarily to the formation of disulfide-linked hemoglobin-skeletal protein adducts. The data suggest that oxidative modification of hemoglobin and membrane skeletal proteins by divicine may be key events in the mechanism underlying favism. PMID:11452148

  18. Kinetic Monte Carlo simulations of thermally activated magnetization reversal in dual-layer Exchange Coupled Composite recording media

    NASA Astrophysics Data System (ADS)

    Plumer, M. L.; Almudallal, A. M.; Mercer, J. I.; Whitehead, J. P.; Fal, T. J.

    The kinetic Monte Carlo (KMC) method developed for thermally activated magnetic reversal processes in single-layer recording media has been extended to study dual-layer Exchange Coupled Composition (ECC) media used in current and next generations of disc drives. The attempt frequency is derived from the Langer formalism with the saddle point determined using a variant of Bellman Ford algorithm. Complication (such as stagnation) arising from coupled grains having metastable states are addressed. MH-hysteresis loops are calculated over a wide range of anisotropy ratios, sweep rates and inter-layer coupling parameter. Results are compared with standard micromagnetics at fast sweep rates and experimental results at slow sweep rates.

  19. Surface modification of polypropylene non-woven fibers with TiO2 nanoparticles via layer-by-layer self assembly method: Preparation and photocatalytic activity.

    PubMed

    Pavasupree, Suttipan; Dubas, Stephan T; Rangkupan, Ratthapol

    2015-11-01

    Polypropylene (PP) meltblown fibers were coated with titanium dioxide (TiO2) nanoparticles using layer-by-layer (LbL) deposition technique. The fibers were first modified with 3 layers of poly(4-styrenesulfonic acid) (PSS) and poly(diallyl-dimethylammonium chloride) (PDADMAC) to improve the anchoring of the TiO2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic TiO2 nanoparticles to construct TiO2/PDADMAC bilayer in the LbL fashion. The number of deposited TiO2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust TiO2 loading. The LbL technique showed higher TiO2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue (MB). Results showed that the TiO2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of TiO2 powder dispersed in solution. The deposition of TiO2 3 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4hr. TiO2-LbL constructions also preserved TiO2 adhesion on substrate surface after 1cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of TiO2 particles from the substrate outer surface. However, even in the third cycle, the TiO2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8hr of treatment. PMID:26574088

  20. Efficient solar photocatalytic activity of TiO2 coated nano-porous silicon by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Sampath, Sridhar; Maydannik, Philipp; Ivanova, Tatiana; Shestakova, Marina; Homola, Tomáš; Bryukvin, Anton; Sillanpää, Mika; Nagumothu, Rameshbabu; Alagan, Viswanathan

    2016-09-01

    In the present study, TiO2 coated nano-porous silicon (TiO2/PS) was prepared by atomic layer deposition (ALD) whereas porous silicon was prepared by stain etching method for efficient solar photocatalytic activity. TiO2/PS was characterized by FESEM, AFM, XRD, XPS and DRS UV-vis spectrophotometer. Absorbance spectrum revealed that TiO2/PS absorbs complete solar light with wave length range of 300 nm-800 nm and most importantly, it absorbs stronger visible light than UV light. The reason for efficient solar light absorption of TiO2/PS is that nanostructured TiO2 layer absorbs UV light and nano-porous silicon layer absorbs visible light which is transparent to TiO2 layer. The amount of visible light absorption of TiO2/PS directly increases with increase of silicon etching time. The effect of silicon etching time of TiO2/PS on solar photocatalytic activity was investigated towards methylene blue dye degradation. Layer by layer solar absorption mechanism was used to explain the enhanced photocatalytic activity of TiO2/PS solar absorber. According to this, the photo-generated electrons of porous silicon will be effectively injected into TiO2 via hetero junction interface which leads to efficient charge separation even though porous silicon is not participating in any redox reactions in direct.

  1. Antioxidant activity and phenolic profile of various morphological parts of underutilised Baccaurea angulata fruit.

    PubMed

    Ahmed, Idris Adewale; Mikail, Maryam Abimbola; Bin Ibrahim, Muhammad; Bin Hazali, Norazlanshah; Rasad, Mohammad Syaiful Bahari Abdul; Ghani, Radiah Abdul; Wahab, Ridhwan Abdul; Arief, Solachuddin Jahuari; Yahya, Mohammad Noor Adros

    2015-04-01

    Baccaurea angulata is an underutilised tropical fruit of Borneo Island of Malaysia. The effect of solvents was examined on yield, total phenolic (TPC), total flavonoids (TFC), total carotene content (TCC), free radical scavenging activities and lipid peroxidation inhibition activities. The results indicated that the pulp (edible portion) had the highest yield, while methanol extracts were significantly (p < 0.01) found to contain higher TPC, TFC and TCC than phosphate buffered saline (PBS) extracts for all the fruits parts. The methanol extracts also showed remarkable antiradical activity and significant lipid peroxidation inhibition activities, with their IC50 results highly comparable to that of commercial blueberry. The variations in the results among the extracts suggest different interactions, such as negative or antagonistic (interference), additive and synergistic effect interactions. The study indicated that B. angulata like other underutilised tropical fruits contained remarkable primary antioxidants. Thus, the fruit has the potential to be sources of antioxidant components. PMID:25442620

  2. Hippocampal morphology in a rat model of depression: the effects of physical activity.

    PubMed

    Sierakowiak, Adam; Mattsson, Anna; Gómez-Galán, Marta; Feminía, Teresa; Graae, Lisette; Aski, Sahar Nikkhou; Damberg, Peter; Lindskog, Mia; Brené, Stefan; Åberg, Elin

    2014-01-01

    Accumulating in vivo and ex vivo evidences show that humans suffering from depression have decreased hippocampal volume and altered spine density. Moreover, physical activity has an antidepressant effect in humans and in animal models, but to what extent physical activity can affect hippocampal volume and spine numbers in a model for depression is not known. In this study we analyzed whether physical activity affects hippocampal volume and spine density by analyzing a rodent genetic model of depression, Flinders Sensitive Line Rats (FSL), with Magnetic Resonance Imaging (MRI) and ex vivo Golgi staining. We found that physical activity in the form of voluntary wheel running during 5 weeks increased hippocampal volume. Moreover, runners also had larger numbers of thin spines in the dentate gyrus. Our findings support that voluntary wheel running, which is antidepressive in FSL rats, is associated with increased hippocampal volume and spine numbers. PMID:25674191

  3. Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm

    SciTech Connect

    Momblona, C.; Malinkiewicz, O.; Soriano, A.; Gil-Escrig, L.; Bandiello, E.; Scheepers, M.; Bolink, H. J.; Edri, E.

    2014-08-01

    Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging from 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively.

  4. Studies of surface morphology and optical properties of ZnO nanostructures grown on different molarities of TiO2 seed layer

    NASA Astrophysics Data System (ADS)

    Asib, N. A. M.; Afaah, A. N.; Aadila, A.; Rusop, M.; Khusaimi, Z.

    2016-07-01

    Titanium dioxide (TiO2) seed layer was prepared by using sol-gel spin-coating technique, followed by growth of 0.01 M of Zinc oxide (ZnO) nanostructures by solution-immersion. The molarities of TiO2 seed layer were varied from 1.1 M to 0.100 M on glass substrates. The nanostructures thin films were characterized by Field Emission Scanning Electrons Microscope (FESEM), Photoluminescence (PL) spectroscopy and Ultraviolet-Visible (UV-Vis) spectroscopy. FESEM images demonstrate that needle-like ZnO nanostructures are formed on all TiO2 seed layer. The smallest diameter of needle-like ZnO nanostructures (90.3 nm) were deposited on TiO2 seed layer of 0.100 M. PL spectra of the TiO2: ZnO nanostructures thin films show the blue shifted emissions in the UV regions compared to the ZnO thin film. Meanwhile, UV-vis spectra of films display high absorption in the UV region and high trasparency in the visible region. The highest absorbance at UV region was recorded for sample which has 0.100 M of TiO2 seed layer.

  5. Influence of feeding alternative fiber sources on the gastrointestinal fermentation, digestive enzyme activities and mucosa morphology of growing Greylag geese.

    PubMed

    He, L W; Meng, Q X; Li, D Y; Zhang, Y W; Ren, L P

    2015-10-01

    The objective of this trial was to study the influence of dietary fiber sources on the gastrointestinal fermentation, digestive enzyme activity, and mucosa morphology of growing Greylag geese. In total, 240 Greylag geese (28-day-old) were allocated to 4 treatments (15 pens/treatment) differing in dietary fiber source: corn straw silage (CSS group), steam-exploded corn straw (SECS group), steam-exploded wheat straw (SEWS group), or steam-exploded rice straw (SERS group). At 112 days of age, 15 birds per group were euthanized to collect samples. No difference (P > 0.05) was found on all the gastrointestinal pH values and ammonia-nitrogen concentrations between the groups. The CSS and SERS groups had a lower (P < 0.05) proportion of acetic acid in the gizzard than the SECS and SEWS groups. The CSS group had a higher VFA concentration in the jejunum (P < 0.05) and acetic acid proportion (P < 0.01) in the ceca, and a lower (P < 0.01) butyric acid proportion than the other groups except for the SECS group. The SECS group had a higher (P < 0.01) acetic acid proportion and lower (P < 0.05) proportions of propionic acid and valeric acid in the ceca than the SEWS and SERS groups. Different fiber sources resulted in different VFA profiles, especially in the gizzard and ceca. Almost all gastrointestinal protease activities of the CSS group were higher (P < 0.05) than the other groups, along with lower (P < 0.01) amylase activities in the duodenum, jejunum, ileum, and ceca. Lipase activity in proventriculus was highest (P < 0.01) in the SEWS group and its cecal activity was lower (P < 0.01) in the SECS and SEWS groups than the CSS and SERS groups with a higher (P < 0.01) lipase activity in the CSS group than the SERS group. The SECS and SERS groups had a higher cellulase activity in the ceca than the CSS and SEWS groups, with a higher (P < 0.01) rectal cellulase activity in the SERS group than the other groups. There was no

  6. Active control of turbulent boundary layer sound transmission into a vehicle interior

    NASA Astrophysics Data System (ADS)

    Caiazzo, A.; Alujević, N.; Pluymers, B.; Desmet, W.

    2016-09-01

    In high speed automotive, aerospace, and railway transportation, the turbulent boundary layer (TBL) is one of the most important sources of interior noise. The stochastic pressure distribution associated with the turbulence is able to excite significantly structural vibration of vehicle exterior panels. They radiate sound into the vehicle through the interior panels. Therefore, the air flow noise becomes very influential when it comes to the noise vibration and harshness assessment of a vehicle, in particular at low frequencies. Normally, passive solutions, such as sound absorbing materials, are used for reducing the TBL-induced noise transmission into a vehicle interior, which generally improve the structure sound isolation performance. These can achieve excellent isolation performance at higher frequencies, but are unable to deal with the low-frequency interior noise components. In this paper, active control of TBL noise transmission through an acoustically coupled double panel system into a rectangular cavity is examined theoretically. The Corcos model of the TBL pressure distribution is used to model the disturbance. The disturbance is rejected by an active vibration isolation unit reacting between the exterior and the interior panels. Significant reductions of the low-frequency vibrations of the interior panel and the sound pressure in the cavity are observed.

  7. Active Control of Turbulent Boundary Layer Induced Sound Radiation from Multiple Aircraft Panels

    NASA Technical Reports Server (NTRS)

    Gibbs, Gary P.; Cabell, Randolph H.

    2002-01-01

    The objective of this work is to experimentally investigate active structural acoustic control of turbulent boundary layer (TBL) induced sound radiation from multiple panels on an aircraft sidewall. One possible approach for controlling sound radiation from multiple panels is a multi-input/multi-output scheme which considers dynamic coupling between the panels. Unfortunately, this is difficult for more than a few panels, and is impractical for a typical aircraft which contains several hundred such panels. An alternative is to implement a large number of independent control systems. Results from the current work demonstrate the feasibility of reducing broadband radiation from multiple panels utilizing a single-input/single-output (SISO) controller per bay, and is the first known demonstration of active control of TBL induced sound radiation on more than two bays simultaneously. The paper compares sound reduction for fully coupled control of six panels versus independent control on each panel. An online adaptive control scheme for independent control is also demonstrated. This scheme will adjust for slow time varying dynamic systems such as fuselage response changes due to aircraft pressurization, etc.

  8. An electrochemical double layer capacitor using an activated carbon electrode with gel electrolyte binder

    SciTech Connect

    Osaka, Tetsuya, Liu, X.; Nojima, Masashi; Momma, Toshiyuki

    1999-05-01

    An electric double layer capacitor (EDLC) was prepared with an activated carbon powder electrode with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) based gel electrolyte. Ethylene carbonate (EC) and propylene carbonate (PC) were used as plasticizer and tetraethylammonium tetrafluoroborate (TEABF{sub 4}) was used as the supporting electrolyte. An optimized gel electrolyte of PVdF-HFP/PC/EC/TEABF{sub 4} - 23/31/35/11 mass ratio exhibited high ionic conductivity of 5 {times} 10{sup {minus}3} S/cm, high electrode capacitance, and good mechanical strength. An electrode consisting of activated carbon (AC) with the gel electrolyte as the binder (AC/PVdF-HFP based gel, 7/3 mass ratio) showed a higher specific capacitance and a lower ion diffusion resistance within the electrode than a carbon electrode, prepared with PVdF-HFP binder without plasticizer. This suggests that an electrode mixed with the gel electrolyte has a lower ion diffusion resistance inside the electrode. The highest specific capacitance of 123 F/g was achieved with an electrode containing AC with a specific surface area of 2500 m{sup 2}/g. A coin-type EDLC cell with optimized components showed excellent cycleability exceeding 10{sup 4} cycles with ca. 100% coulombic efficiency achieved when charging and discharging was repeated between 1.0 and 2.5 V at 1.66 mA/cm{sup 2}.

  9. [Aluminum coordination and active sites on aluminas, Y-zeolites and pillared layered silicates]. Progress report

    SciTech Connect

    Fripiat, J.J.

    1994-02-01

    This report is organized in four sections. In the first the authors will outline structural features which are common to all fine grained alumina, as well as to non-framework alumina in zeolites. This section will be followed by a study of the surface vs. bulk coordination of aluminum. The third section will deal with measurement of the number of acid sites and the scaling of their strength. The fourth and last section will describe three model reactions: the isomerization of 1-butene and of 2 cis-butene; the isomerization and disproportionation of oxtho-xylene; and the transformation of trichloroethane into vinyl chloride followed by the polymerization of the vinyl chloride. The relationship between chemical activity and selectivity and what is known of the local structure of the active catalytic sites will be underlined. Other kinds of zeolites besides Y zeolite have been studied. Instead of the aluminum pillared silicates they found it more interesting to study the substitution of silicon by aluminum in a layered structure containing a permanent porosity (aluminated sepiolite).

  10. [Effect of the atmospheric ozone layer on the biologically active ultraviolet radiation on the earth's surface].

    PubMed

    Schulze, R; Kasten, F

    1975-08-01

    Based on measurements of the spectral irradiation intensity of UV-B global radiation by Bener (1960) and on the curve of spectral skin erythema effects newly measured by Urbach and Berger (1972), the biologically active UV-radiation at earth's surface has been calculated as a function of sun's altitude and atmospheric ozone content in so-called "Biological Units": BE = mWh cm-2 times erythema efficacy. On the basis of these data, the total daily, monthly, and yearly amounts of biologically active UV-radiation have been determined for the different geographical latitudes and various ozone contents. Approximately two thirds of BU hit the equatorial zone from 35 degrees south to 35 degrees north. Provided that the stratospheric ozone layer would be reduced by ten per cent from the exhaust gases of supersonic planes flying at high-altitude, an increase of BU would result amounting to 18% at the equator, to 19% in middle latitudes, and to 22% at the poles.

  11. Characterization of purified human Bact spliceosomal complexes reveals compositional and morphological changes during spliceosome activation and first step catalysis

    PubMed Central

    Bessonov, Sergey; Anokhina, Maria; Krasauskas, Andrius; Golas, Monika M.; Sander, Bjoern; Will, Cindy L.; Urlaub, Henning; Stark, Holger; Lührmann, Reinhard

    2010-01-01

    To better understand the compositional and structural dynamics of the human spliceosome during its activation, we set out to isolate spliceosomal complexes formed after precatalytic B but prior to catalytically active C complexes. By shortening the polypyrimidine tract of the PM5 pre-mRNA, which lacks a 3′ splice site and 3′ exon, we stalled spliceosome assembly at the activation stage. We subsequently affinity purified human Bact complexes under the same conditions previously used to isolate B and C complexes, and analyzed their protein composition by mass spectrometry. A comparison of the protein composition of these complexes allowed a fine dissection of compositional changes during the B to Bact and Bact to C transitions, and comparisons with the Saccharomyces cerevisiae Bact complex revealed that the compositional dynamics of the spliceosome during activation are largely conserved between lower and higher eukaryotes. Human SF3b155 and CDC5L were shown to be phosphorylated specifically during the B to Bact and Bact to C transition, respectively, suggesting these modifications function at these stages of splicing. The two-dimensional structure of the human Bact complex was determined by electron microscopy, and a comparison with the B complex revealed that the morphology of the human spliceosome changes significantly during its activation. The overall architecture of the human and S. cerevisiae Bact complex is similar, suggesting that many of the higher order interactions among spliceosomal components, as well as their dynamics, are also largely conserved. PMID:20980672

  12. Enhanced Electrocatalytic Performance for Oxygen Reduction via Active Interfaces of Layer-By-Layered Titanium Nitride/Titanium Carbonitride Structures

    PubMed Central

    Jin, Zhaoyu; Li, Panpan; Xiao, Dan

    2014-01-01

    Cathode materials always limit the performance of fuel cells while the commercial platinum-based catalysts hardly meet the requirements of low cost, durable and stable. Here a non-precious metal oxygen reduction reaction (ORR) electocatalyst based on titanium nitride/titanium carbonitride hierarchical structures (TNTCNHS) is demonstrated as high activity as Pt/C. In alkaline condition, tuning interface/mass ratio of TiN/TiCN, we observed the onset potential of ~0.93 V vs. RHE and a limit diffusion current density of ~5.1 mA cm−2 (at a rotating speed of 1600 rpm) on TNTCNHS with a relative low catalyst loading of ~0.1 mg cm−2. The kinetic current, durability and tolerance to crossover effect studies reveal even more efficient than carbon-supported platinum. The architecture fabrication for such electrocatalyst is easy to realize in industrial-scale facilities, for the use of chemical vapor deposition (CVD) technique could support a huge area production (more than 10000 cm2 for one pot) to satisfy the enormous market requirements in the future. PMID:25335930

  13. Enhanced electrocatalytic performance for oxygen reduction via active interfaces of layer-by-layered titanium nitride/titanium carbonitride structures.

    PubMed

    Jin, Zhaoyu; Li, Panpan; Xiao, Dan

    2014-01-01

    Cathode materials always limit the performance of fuel cells while the commercial platinum-based catalysts hardly meet the requirements of low cost, durable and stable. Here a non-precious metal oxygen reduction reaction (ORR) electocatalyst based on titanium nitride/titanium carbonitride hierarchical structures (TNTCNHS) is demonstrated as high activity as Pt/C. In alkaline condition, tuning interface/mass ratio of TiN/TiCN, we observed the onset potential of ~0.93 V vs. RHE and a limit diffusion current density of ~5.1 mA cm(-2) (at a rotating speed of 1600 rpm) on TNTCNHS with a relative low catalyst loading of ~0.1 mg cm(-2). The kinetic current, durability and tolerance to crossover effect studies reveal even more efficient than carbon-supported platinum. The architecture fabrication for such electrocatalyst is easy to realize in industrial-scale facilities, for the use of chemical vapor deposition (CVD) technique could support a huge area production (more than 10000 cm(2) for one pot) to satisfy the enormous market requirements in the future. PMID:25335930

  14. p-GaAs(Cs,O)-photocathodes: Demarcation of domains of validity for practical models of the activation layer

    SciTech Connect

    Bakin, V. V.; Toropetsky, K. V.; Scheibler, H. E.; Terekhov, A. S.; Jones, L. B.; Militsyn, B. L.; Noakes, T. C. Q.

    2015-05-04

    The (Cs,O)-activation procedure for p-GaAs(Cs,O)-photocathodes was studied with the aim of demarcating the domains of validity for the two practical models of the (Cs,O)-activation layer: The dipole layer (DL) model and the heterojunction (HJ) model. To do this, the photocathode was activated far beyond the normal maximum of quantum efficiency, and several photocathode parameters were measured periodically during this process. In doing so, the data obtained enabled us to determine the domains of validity for the DL- and HJ-models, to define more precisely the characteristic parameters of the photocathode within both of these domains and thus to reveal the peculiarities of the influence of the (Cs,O)-layer on the photoelectron escape probability.

  15. Impact of active layer thickness in thin-film transistors based on Zinc Oxide by ultrasonic spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Dominguez, Miguel A.; Flores, Francisco; Luna, Adan; Martinez, Javier; Luna-Lopez, Jose A.; Alcantara, Salvador; Rosales, Pedro; Reyes, Claudia; Orduña, Abdu

    2015-07-01

    In this work, the preparation of Zinc Oxide (ZnO) films by ultrasonic spray pyrolysis at low-temperature and its application in thin-film transistors (TFTs) are presented, as well, the impact of the active layer thickness and gate dielectric thickness in the electrical performance of the ZnO TFTs. A thinner active layer resulted in better transfer characteristics such as higher on/off-current ratio, while a thicker active layer resulted in better output characteristics. The ZnO films were deposited from 0.2 M precursor solution of Zinc acetate in methanol, using air as carrier gas on a hotplate at 200 °C. The ZnO films obtained at 200 °C were characterized by optical transmittance, Photoluminescence spectroscopy and X-ray diffraction.

  16. Estimating 1992-2000 average active layer thickness on the Alaskan North Slope from remotely sensed surface subsidence

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Schaefer, Kevin; Zhang, Tingjun; Wahr, John

    2012-01-01

    The measurement of temporal changes in active layer thickness (ALT) is crucial to monitoring permafrost degradation in the Arctic. We develop a retrieval algorithm to estimate long-term average ALT using thaw-season surface subsidence derived from spaceborne interferometric synthetic aperture radar (InSAR) measurements. Our algorithm uses a model of vertical distribution of water content within the active layer accounting for soil texture, organic matter, and moisture. We determine the 1992-2000 average ALT for an 80 × 100 km study area of continuous permafrost on the North Slope of Alaska near Prudhoe Bay. We obtain an ALT of 30-50 cm over moist tundra areas, and a larger ALT of 50-80 cm over wet tundra areas. Our estimated ALT values match in situ measurements at Circumpolar Active Layer Monitoring (CALM) sites within uncertainties. Our results demonstrate that InSAR can provide ALT estimates over large areas at high spatial resolution.

  17. Wrinkled substrate and Indium Tin Oxide-free transparent electrode making organic solar cells thinner in active layer

    NASA Astrophysics Data System (ADS)

    Liu, Kong; Lu, Shudi; Yue, Shizhong; Ren, Kuankuan; Azam, Muhammad; Tan, Furui; Wang, Zhijie; Qu, Shengchun; Wang, Zhanguo

    2016-11-01

    To enable organic solar cells with a competent charge transport efficiency, reducing the thickness of active layer without sacrificing light absorption efficiency turns out to be of high feasibility. Herein, organic solar cells on wrinkled metal surface are designed. The purposely wrinkled Al/Au film with a smooth surface provides a unique scaffold for constructing thin organic photovoltaic devices by avoiding pinholes and defects around sharp edges in conventional nanostructures. The corresponding surface light trapping effect enables the thin active layer (PTB7-Th:PC71BM) with a high absorption efficiency. With the innovative MoO3/Ag/ZnS film as the top transparent electrode, the resulting Indium Tin Oxide-free wrinkled devices show a power conversion efficiency as 7.57% (50 nm active layer), higher than the planner counterparts. Thus, this paper provides a new methodology to improve the performance of organic solar cells by balancing the mutual restraint factors to a high level.

  18. Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: study of direct voltammetry and bioelectrocatalytic activity.

    PubMed

    Saadati, Shagayegh; Salimi, Abdollah; Hallaj, Rahman; Rostami, Amin

    2012-11-13

    A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH(2)-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH(2)-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH(2)-IL and negatively charged catalase a sensitive H(2)O(2) biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k(s)) and Michaelis-Menten constant (K(M)) of immobilized catalase were 3.32×10(-12) mol cm(-2), 5.28s(-1) and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 μA mM(-1)cm(-2) and low detection limit of 100 nM at concentration range up to 2.1 mM.

  19. High reliable and stable organic field-effect transistor nonvolatile memory with a poly(4-vinyl phenol) charge trapping layer based on a pn-heterojunction active layer

    NASA Astrophysics Data System (ADS)

    Xiang, Lanyi; Ying, Jun; Han, Jinhua; Zhang, Letian; Wang, Wei

    2016-04-01

    In this letter, we demonstrate a high reliable and stable organic field-effect transistor (OFET) based nonvolatile memory (NVM) with a polymer poly(4-vinyl phenol) (PVP) as the charge trapping layer. In the unipolar OFETs, the inreversible shifts of the turn-on voltage (Von) and severe degradation of the memory window (ΔVon) at programming (P) and erasing (E) voltages, respectively, block their application in NVMs. The obstacle is overcome by using a pn-heterojunction as the active layer in the OFET memory, which supplied a holes and electrons accumulating channel at the supplied P and E voltages, respectively. Both holes and electrons transferring from the channels to PVP layer and overwriting the trapped charges with an opposite polarity result in the reliable bidirectional shifts of Von at P and E voltages, respectively. The heterojunction OFET exhibits excellent nonvolatile memory characteristics, with a large ΔVon of 8.5 V, desired reading (R) voltage at 0 V, reliable P/R/E/R dynamic endurance over 100 cycles and a long retention time over 10 years.

  20. Active diagenetic formation of metal-rich layers in N. E. Atlantic sediments

    NASA Astrophysics Data System (ADS)

    Wallace, H. E.; Thomson, J.; Wilson, T. R. S.; Weaver, P. P. E.; Higgs, N. C.; Hydes, D. J.

    1988-06-01

    Sediment cores from the Porcupine Abyssal Plain exhibit an indurated layer 0.5-3 cm thick at depths of approximately 50 cm. This is some 15-20 cm below the glacial/Holocene transition as interpreted by radiocarbon dating and the palaeontological criteria of RUDDIMAN and MCINTYRE (1981). The layer is forming currently at the oxic/post-oxic boundary in the sediments, as revealed by pore water data: O 2 and NO -3 are present in solution above the layer, while Fe 2+, Mn 2+, PO 3-4 and NH +4 are present in solution below, and all these species show concentration gradients indicating fluxes into the layer. These data are consistent with the hypothesis for the initiation and sustained formation of such layers proposed by WILSONet al. (1986a,b). The elements Mn, Ni, Co, Fe, P, V, Cu, Zn and U are all enriched to varying degrees in the vicinity of the layer. Some differential stratification of these elements in the vertical, consistent with a redox control, is observed at one site with a 0.5 cm layer, with Mn, Ni and Co above, Fe, P, V and Cu in the layer, and U below. At another site the metal-rich layer has higher Fe and P concentrations and is more indurated. Here all enrichments except Co are contained within a single layer sample, 3 cm thick.

  1. Morphological evaluation of sperm from infertile men selected by magnetic activated cell sorting (MACS).

    PubMed

    Curti, Gianni; Skowronek, Fernanda; Vernochi, Rita; Rodriguez-Buzzi, Ana Laura; Rodriguez-Buzzi, Juan Carlos; Casanova, Gabriela; Sapiro, Rossana

    2014-12-01

    Electron microscopy analysis performed in five infertile human subjects after sperm selection by swim-up followed by magnetic activated cell sorting (MACS) demonstrated a decrease in the number of spermatozoa with characteristics compatible with cell death. However, no significant differences were found when the swim-up/MACS semen fraction was compared with swim-up fraction alone.

  2. Active Control of Panel Vibrations Induced by a Boundary Layer Flow

    NASA Technical Reports Server (NTRS)

    Chow, Pao-Liu

    1998-01-01

    In re