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Sample records for nanometer-scale mass transport

  1. Membranes for nanometer-scale mass fast transport

    DOEpatents

    Bakajin, Olgica; Holt, Jason; Noy, Aleksandr; Park, Hyung Gyu

    2011-10-18

    Nanoporous membranes comprising single walled, double walled, and multiwalled carbon nanotubes embedded in a matrix material were fabricated for fluid mechanics and mass transfer studies on the nanometer scale and commercial applications. Average pore size can be 2 nm to 20 nm, or seven nm or less, or two nanometers or less. The membrane can be free of large voids spanning the membrane such that transport of material such as gas or liquid occurs exclusively through the tubes. Fast fluid, vapor, and liquid transport are observed. Versatile micromachining methods can be used for membrane fabrication. A single chip can comprise multiple membranes. These membranes are a robust platform for the study of confined molecular transport, with applications in liquid and gas separations and chemical sensing including desalination, dialysis, and fabric formation.

  2. Fabrication of a Carbon Nanotube-Embedded Silicon Nitride Membrane for Studies of Nanometer-Scale Mass Transport

    SciTech Connect

    Holt, J K; Noy, A; Huser, T; Eaglesham, D; Bakajin, O

    2004-08-25

    A membrane consisting of multiwall carbon nanotubes embedded in a silicon nitride matrix was fabricated for fluid mechanics studies on the nanometer scale. Characterization by tracer diffusion and scanning electron microscopy suggests that the membrane is free of large voids. An upper limit to the diffusive flux of D{sub 2}O of 2.4x10-{sup 8} mole/m{sup 2}-s was determined, indicating extremely slow transport. By contrast, hydrodynamic calculations of water flow across a nanotube membrane of similar specifications predict a much higher molar flux of 1.91 mole/m{sup 2}-s, suggesting that the nanotubes produced possess a 'bamboo' morphology. The carbon nanotube membranes were used to make nanoporous silicon nitride membranes, fabricated by sacrificial removal of the carbon. Nitrogen flow measurements on these structures give a membrane permeance of 4.7x10{sup -4} mole/m{sup 2}-s-Pa at a pore density of 4x10{sup 10} cm{sup -2}. Using a Knudsen diffusion model, the average pore size of this membrane is estimated to be 66 nm, which agrees well with TEM observations of the multiwall carbon nanotube outer diameter. These membranes are a robust platform for the study of confined molecular transport, with applications inseparations and chemical sensing.

  3. Mass-producible and efficient optical antennas with CMOS-fabricated nanometer-scale gap.

    PubMed

    Seok, Tae Joon; Jamshidi, Arash; Eggleston, Michael; Wu, Ming C

    2013-07-15

    Optical antennas have been widely used for sensitive photodetection, efficient light emission, high resolution imaging, and biochemical sensing because of their ability to capture and focus light energy beyond the diffraction limit. However, widespread application of optical antennas has been limited due to lack of appropriate methods for uniform and large area fabrication of antennas as well as difficulty in achieving an efficient design with small mode volume (gap spacing < 10nm). Here, we present a novel optical antenna design, arch-dipole antenna, with optimal radiation efficiency and small mode volume, 5 nm gap spacing, fabricated by CMOS-compatible deep-UV spacer lithography. We demonstrate strong surface-enhanced Raman spectroscopy (SERS) signal with an enhancement factor exceeding 108 from the arch-dipole antenna array, which is two orders of magnitude stronger than that from the standard dipole antenna array fabricated by e-beam lithography. Since the antenna gap spacing, the critical dimension of the antenna, can be defined by deep-UV lithography, efficient optical antenna arrays with nanometer-scale gap can be mass-produced using current CMOS technology. PMID:23938507

  4. Pseudopotential-based electron quantum transport: Theoretical formulation and application to nanometer-scale silicon nanowire transistors

    NASA Astrophysics Data System (ADS)

    Fang, Jingtian; Vandenberghe, William G.; Fu, Bo; Fischetti, Massimo V.

    2016-01-01

    We present a formalism to treat quantum electronic transport at the nanometer scale based on empirical pseudopotentials. This formalism offers explicit atomistic wavefunctions and an accurate band structure, enabling a detailed study of the characteristics of devices with a nanometer-scale channel and body. Assuming externally applied potentials that change slowly along the electron-transport direction, we invoke the envelope-wavefunction approximation to apply the open boundary conditions and to develop the transport equations. We construct the full-band open boundary conditions (self-energies of device contacts) from the complex band structure of the contacts. We solve the transport equations and present the expressions required to calculate the device characteristics, such as device current and charge density. We apply this formalism to study ballistic transport in a gate-all-around (GAA) silicon nanowire field-effect transistor with a body-size of 0.39 nm, a gate length of 6.52 nm, and an effective oxide thickness of 0.43 nm. Simulation results show that this device exhibits a subthreshold slope (SS) of ˜66 mV/decade and a drain-induced barrier-lowering of ˜2.5 mV/V. Our theoretical calculations predict that low-dimensionality channels in a 3D GAA architecture are able to meet the performance requirements of future devices in terms of SS swing and electrostatic control.

  5. A switchable DNA origami nanochannel for regulating molecular transport at the nanometer scale

    NASA Astrophysics Data System (ADS)

    Wang, Dianming; Zhang, Yiyang; Wang, Miao; Dong, Yuanchen; Zhou, Chao; Isbell, Mark Antonin; Yang, Zhongqiang; Liu, Huajie; Liu, Dongsheng

    2016-02-01

    A nanochannel with a shutter at one end was built by DNA nanotechnology. Using DNA hybridization the shutter could be opened or closed, influencing the transport of materials through the channel. This process was visualized by an enzyme cascade reaction occurring in the structure.A nanochannel with a shutter at one end was built by DNA nanotechnology. Using DNA hybridization the shutter could be opened or closed, influencing the transport of materials through the channel. This process was visualized by an enzyme cascade reaction occurring in the structure. Electronic supplementary information (ESI) available: Experimental details including methods, materials, ESI figures and DNA sequences. See DOI: 10.1039/c5nr08206d

  6. Combined Atomic Force Microscope-Based Topographical Imaging and Nanometer Scale Resolved Proximal Probe Thermal Desorption/Electrospray Ionization-Mass Spectrometry

    SciTech Connect

    Ovchinnikova, Olga S; Nikiforov, Maxim; Bradshaw, James A; Jesse, Stephen; Van Berkel, Gary J

    2011-01-01

    Nanometer scale proximal probe thermal desorption/electrospray ionization mass spectrometry (TD/ESI-MS) was demonstrated for molecular surface sampling of caffeine from a thin film using a 30 nm diameter nano-thermal analysis (nano-TA) probe tip in an atomic force microscope (AFM) coupled via a vapor transfer line and ESI interface to a MS detection platform. Using a probe temperature of 350 C and a spot sampling time of 30 s, conical desorption craters 250 nm in diameter and 100 nm deep were created as shown through subsequent topographical imaging of the surface within the same system. Automated sampling of a 5 x 2 array of spots, with 2 m spacing between spots, and real time selective detection of the desorbed caffeine using tandem mass spectrometry was also demonstrated. Estimated from the crater volume (~2x106 nm3), only about 10 amol (2 fg) of caffeine was liberated from each thermal desorption crater in the thin film. These results illustrate a relatively simple experimental setup and means to acquire in automated fashion sub-micrometer scale spatial sampling resolution and mass spectral detection of materials amenable to TD. The ability to achieve MS-based chemical imaging with 250 nm scale spatial resolution with this system is anticipated.

  7. Nanometer scale marker for fluorescent microscopy

    SciTech Connect

    Hiraga, Takashi; Iketaki, Yoshinori; Watanabe, Takeshi; Ohyi, Hideyuki; Kobayashi, Kazumasa; Yamamoto, Noritaka; Mizokuro, Toshiko; Fujii, Masaaki

    2005-07-15

    To establish a calibration method of optical performance in fluorescence microscopy, we fabricated a fluorescent nanometer-scale marker by combining a dry dye method for polymer film and fine lithography. The marker has a 50 nm line-and-space fluorescent pattern, finer than the optical diffraction limit. A spin-coated poly(methyl methacrylate) thin film on a silicon wafer was densely doped with Rhodamine 6G using a simple vacuum process, named the vapor-transportation method, and then the pattern was formed on the film using electron-beam lithography. The figure accuracy of the fabricated marker was calibrated by electron microscopes. Using this marker, one can quantitatively evaluate the optical properties; i.e., the contrast-transfer function, the point-spread function, magnification, and so on. To show practical use of the marker, we demonstrated the evaluation of a fluorescent microscope system.

  8. Placement of oppositely charged aminoacids at a polypeptide termini determines the voltage-controlled braking of polymer transport through nanometer-scale pores.

    PubMed

    Asandei, Alina; Chinappi, Mauro; Lee, Jong-Kook; Ho Seo, Chang; Mereuta, Loredana; Park, Yoonkyung; Luchian, Tudor

    2015-01-01

    Protein and solid-state nanometer-scale pores are being developed for the detection, analysis, and manipulation of single molecules. In the simplest embodiment, the entry of a molecule into a nanopore causes a reduction in the latter's ionic conductance. The ionic current blockade depth and residence time have been shown to provide detailed information on the size, adsorbed charge, and other properties of molecules. Here we describe the use of the nanopore formed by Staphylococcus aureus α-hemolysin and polypeptides with oppositely charged segments at the N- and C-termini to increase both the polypeptide capture rate and mean residence time of them in the pore, regardless of the polarity of the applied electrostatic potential. The technique provides the means to improve the signal to noise of single molecule nanopore-based measurements. PMID:26029865

  9. Placement of oppositely charged aminoacids at a polypeptide termini determines the voltage-controlled braking of polymer transport through nanometer-scale pores

    PubMed Central

    Asandei, Alina; Chinappi, Mauro; Lee, Jong-kook; Ho Seo, Chang; Mereuta, Loredana; Park, Yoonkyung; Luchian, Tudor

    2015-01-01

    Protein and solid-state nanometer-scale pores are being developed for the detection, analysis, and manipulation of single molecules. In the simplest embodiment, the entry of a molecule into a nanopore causes a reduction in the latter’s ionic conductance. The ionic current blockade depth and residence time have been shown to provide detailed information on the size, adsorbed charge, and other properties of molecules. Here we describe the use of the nanopore formed by Staphylococcus aureus α-hemolysin and polypeptides with oppositely charged segments at the N- and C-termini to increase both the polypeptide capture rate and mean residence time of them in the pore, regardless of the polarity of the applied electrostatic potential. The technique provides the means to improve the signal to noise of single molecule nanopore-based measurements. PMID:26029865

  10. Functional nanometer-scale structures

    NASA Astrophysics Data System (ADS)

    Chan, Tsz On Mario

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

  11. Electrochemistry at Nanometer-Scaled Electrodes

    ERIC Educational Resources Information Center

    Watkins, John J.; Bo Zhang; White, Henry S.

    2005-01-01

    Electrochemical studies using nanometer-scaled electrodes are leading to better insights into electrochemical kinetics, interfacial structure, and chemical analysis. Various methods of preparing electrodes of nanometer dimensions are discussed and a few examples of their behavior and applications in relatively simple electrochemical experiments…

  12. Nanometer-scale temperature measurements of phase change memory and carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Grosse, Kyle Lane

    This work investigates nanometer-scale thermometry and thermal transport in new electronic devices to mitigate future electronic energy consumption. Nanometer-scale thermal transport is integral to electronic energy consumption and limits current electronic performance. New electronic devices are required to improve future electronic performance and energy consumption, but heat generation is not well understood in these new technologies. Thermal transport deviates significantly at the nanometer-scale from macroscopic systems as low dimensional materials, grain structure, interfaces, and thermoelectric effects can dominate electronic performance. This work develops and implements an atomic force microscopy (AFM) based nanometer-scale thermometry technique, known as scanning Joule expansion microscopy (SJEM), to measure nanometer-scale heat generation in new graphene and phase change memory (PCM) devices, which have potential to improve performance and energy consumption of future electronics. Nanometer-scale thermometry of chemical vapor deposition (CVD) grown graphene measured the heat generation at graphene wrinkles and grain boundaries (GBs). Graphene is an atomically-thin, two dimensional (2D) carbon material with promising applications in new electronic devices. Comparing measurements and predictions of CVD graphene heating predicted the resistivity, voltage drop, and temperature rise across the one dimensional (1D) GB defects. This work measured the nanometer-scale temperature rise of thin film Ge2Sb2Te5 (GST) based PCM due to Joule, thermoelectric, interface, and grain structure effects. PCM has potential to reduce energy consumption and improve performance of future electronic memory. A new nanometer-scale thermometry technique is developed for independent and direct observation of Joule and thermoelectric effects at the nanometer-scale, and the technique is demonstrated by SJEM measurements of GST devices. Uniform heating and GST properties are observed for

  13. Nanometer scale thermometry in a living cell

    PubMed Central

    Kucsko, G.; Maurer, P. C.; Yao, N. Y.; Kubo, M.; Noh, H. J.; Lo, P. K.; Park, H.; Lukin, M. D.

    2014-01-01

    Sensitive probing of temperature variations on nanometer scales represents an outstanding challenge in many areas of modern science and technology1. In particular, a thermometer capable of sub-degree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool for many areas of biological, physical and chemical research; possibilities range from the temperature-induced control of gene expression2–5 and tumor metabolism6 to the cell-selective treatment of disease7,8 and the study of heat dissipation in integrated circuits1. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the sub-cellular level2–5. Here, we demonstrate a new approach to nanoscale thermometry that utilizes coherent manipulation of the electronic spin associated with nitrogen-vacancy (NV) color centers in diamond. We show the ability to detect temperature variations down to 1.8 mK (sensitivity of 9mK/Hz) in an ultra-pure bulk diamond sample. Using NV centers in diamond nanocrystals (nanodiamonds, NDs), we directly measure the local thermal environment at length scales down to 200 nm. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the sub-cellular level, enabling unique potential applications in life sciences. PMID:23903748

  14. Imaging nanometer-scale beamlets arrays of relativistic electron beams

    SciTech Connect

    Li, R. K.; To, H.; Musumeci, P.

    2012-12-21

    In this paper we study the evolution of nanometer scale transverse density modulation of a high brightness electron beam through a drift and simple focusing channel. With the help of particle tracking simulations we analyze the effects of space charge forces, emittance and energy spread on the feasibility of recovering an initial nm-scale transverse modulation after transport through a magnifying optical system. These studies are relevant for applications such as time-resolved MeV transmission electron microscopy and in the high brightness electron beam community due to the recent developments of nano-structured cathodes and due to the possibility of taking advantage of nm-structures in the beam for coherent radiation generation.

  15. Cell biology of the future: Nanometer-scale cellular cartography

    PubMed Central

    2015-01-01

    Understanding cellular structure is key to understanding cellular regulation. New developments in super-resolution fluorescence imaging, electron microscopy, and quantitative image analysis methods are now providing some of the first three-dimensional dynamic maps of biomolecules at the nanometer scale. These new maps—comprehensive nanometer-scale cellular cartographies—will reveal how the molecular organization of cells influences their diverse and changeable activities. PMID:26483557

  16. Cell biology of the future: Nanometer-scale cellular cartography.

    PubMed

    Taraska, Justin W

    2015-10-26

    Understanding cellular structure is key to understanding cellular regulation. New developments in super-resolution fluorescence imaging, electron microscopy, and quantitative image analysis methods are now providing some of the first three-dimensional dynamic maps of biomolecules at the nanometer scale. These new maps--comprehensive nanometer-scale cellular cartographies--will reveal how the molecular organization of cells influences their diverse and changeable activities. PMID:26483557

  17. Flow and evaporation in single micrometer and nanometer scale pipes

    SciTech Connect

    Velasco, A. E.; Yang, C.; Siwy, Z. S.; Taborek, P.; Toimil-Molares, M. E.

    2014-07-21

    We report measurements of pressure driven flow of fluids entering vacuum through a single pipe of micrometer or nanometer scale diameter. Nanopores were fabricated by etching a single ion track in polymer or mica foils. A calibrated mass spectrometer was used to measure the flow rates of nitrogen and helium through pipes with diameter ranging from 10 μm to 31 nm. The flow of gaseous and liquid nitrogen was studied near 77 K, while the flow of helium was studied from the lambda point (2.18 K) to above the critical point (5.2 K). Flow rates were controlled by changing the pressure drop across the pipe in the range 0–31 atm. When the pressure in the pipe reached the saturated vapor pressure, an abrupt flow transition was observed. A simple viscous flow model is used to determine the position of the liquid/vapor interface in the pipe. The observed mass flow rates are consistent with no slip boundary conditions.

  18. Substrate comprising a nanometer-scale projection array

    DOEpatents

    Cui, Yi; Zhu, Jia; Hsu, Ching-Mei; Connor, Stephen T; Yu, Zongfu; Fan, Shanhui; Burkhard, George

    2012-11-27

    A method for forming a substrate comprising nanometer-scale pillars or cones that project from the surface of the substrate is disclosed. The method enables control over physical characteristics of the projections including diameter, sidewall angle, and tip shape. The method further enables control over the arrangement of the projections including characteristics such as center-to-center spacing and separation distance.

  19. Nanometer-scale complexity, growth, and diagenesis in desert varnish

    NASA Astrophysics Data System (ADS)

    Garvie, Laurence A. J.; Burt, Donald M.; Buseck, Peter R.

    2008-03-01

    Nanometer-scale element mapping and spectroscopy of desert varnishfrom the northern Sonoran Desert in southwestern Arizona reveala dynamic disequilibrium system characterized by postdepositionalmineralogical, chemical, and structural changes activated byliquid water. Lack of equilibrium is suggested by the largevariety of coexisting Mn phases. Sparse secondary Ba and Srsulfates also occur, as do carbonaceous particles. IndividualMn-oxide particles contain variable concentrations of Ba andCe, reflecting their role as repositories of trace elements,presumably derived from atmospheric aerosols. Desert varnishis analogous to more familiar sediments in displaying authigenicand diagenetic structures, but with total sediment thicknesses<1 mm and structures at the nanometer scale. As such, itis neither a weathering rind nor patina, but a unique subaerialsediment that is in dynamic disequilibrium. Our results suggestcontinuing adjustment of varnish to changing environmental conditions.

  20. Programmable nanometer-scale electrolytic metal deposition and depletion

    DOEpatents

    Lee, James Weifu [Oak Ridge, TN; Greenbaum, Elias [Oak Ridge, TN

    2002-09-10

    A method of nanometer-scale deposition of a metal onto a nanostructure includes the steps of: providing a substrate having thereon at least two electrically conductive nanostructures spaced no more than about 50 .mu.m apart; and depositing metal on at least one of the nanostructures by electric field-directed, programmable, pulsed electrolytic metal deposition. Moreover, a method of nanometer-scale depletion of a metal from a nanostructure includes the steps of providing a substrate having thereon at least two electrically conductive nanostructures spaced no more than about 50 .mu.m apart, at least one of the nanostructures having a metal disposed thereon; and depleting at least a portion of the metal from the nanostructure by electric field-directed, programmable, pulsed electrolytic metal depletion. A bypass circuit enables ultra-finely controlled deposition.

  1. Nanometer scale imaging with table top extreme ultraviolet sources

    NASA Astrophysics Data System (ADS)

    Wachulak, Przemyslaw W.; Sandberg, Richard L.; Isoyan, Artak; Urbanski, Lukasz; Bartnik, Andrzej; Bartels, Randy A.; Menoni, Carmen S.; Fiedorowicz, Henryk; Rocca, Jorge J.; Marconi, Mario C.

    2010-12-01

    Decreasing the illumination wavelength allows to improve the spatial resolution in photon-based imaging systems and enables a nanometer-scale spatial resolution. Due to a significant interest in nanometer-scale spatial resolution imaging short wavelengths from extreme ultraviolet (EUV) region are often used. A few examples of various imaging techniques, such as holography, zone plate EUV microscopy, computer generated hologram EUV reconstruction, lens-less diffraction imaging and generalized Talbot self-imaging will be presented utilizing coherent and incoherent EUV sources. Some of these EUV imaging techniques lead to the high spatial resolution, better than 50nm in a very short exposure time. The techniques, presented herein, have potential to be used in actinic mask inspection for EUV lithography, mask-less lithographic processes in the nanofabrication, in material science or biology.

  2. Dewetting of evaporating thin films over nanometer-scale topographies

    NASA Astrophysics Data System (ADS)

    Akbarzadeh, A. M.; Moosavi, A.; Moghimi Kheirabadi, A.

    2014-07-01

    A lubrication model is used to study dewetting of an evaporating thin film layer over a solid substrate with a nanometer-scale topography. The effects of the geometry of the topography, the contact angle, the film thickness, and the slippage on the dewetting have been studied. Our results reveal that the evaporation enhances the dewetting process and reduces the depinning time over the topography. Also it is shown that the depinning time is inversely proportional to the slippage and increasing the contact angle may considerably reduce the depinning time, while the film thickness increases the depinning time.

  3. Carbon Nanotubules: Building Blocks for Nanometer-Scale Engineering

    NASA Technical Reports Server (NTRS)

    Sinnott, Susan B.

    1999-01-01

    The proposed work consisted of two projects: the investigation of fluid permeation and diffusion through ultrafiltration membranes composed of carbon nanotubules and the design and study of molecular transistors composed of nanotubules. The progress made on each project is summarized and also discussion about additional projects, one of which is a continuation of work supported by another grant, is included. The first project was Liquid Interactions within a Nanotubule Membrane. The second was the design of nanometer-scale hydrocarbon electronic devices. The third was the investigation of Mechanical properties of Nanotubules and Nanotubule bundles. The fourth project was to investigate the growth mechanisms of Carbon Nanotubules.

  4. Sample method for formation of nanometer scale holes in membranes

    SciTech Connect

    Schenkel, T.; Stach, E.A.; Radmilovic, V.; Park, S.-J.; Persaud, A.

    2003-02-24

    When nanometer scale holes (diameters of 50 to a few hundred nm) are imaged in a scanning electron microscope (SEM) at pressures in the 10{sup -5} to 10{sup -6} torr range, hydrocarbon deposits built up and result in the closing of holes within minutes of imaging. Additionally, electron beam deposition of material from a gas source allows the closing of holes with films of platinum or TEOS oxide. In an instrument equipped both with a focused ion beam (FIB), and an SEM, holes can be formed and then covered with a thin film to form nanopores with controlled openings, ranging down to only a few nanometers.

  5. Quantitative nanometer-scale mapping of dielectric tunability

    SciTech Connect

    Tselev, Alexander; Klein, Andreas; Gassmann, Juergen; Jesse, Stephen; Li, Qian; Kalinin, Sergei V.; Wisinger, Nina Balke

    2015-08-21

    Two scanning probe microscopy techniques—near-field scanning microwave microscopy (SMM) and piezoresponse force microscopy (PFM)—are used to characterize and image tunability in a thin (Ba,Sr)TiO3 film with nanometer scale spatial resolution. While sMIM allows direct probing of tunability by measurement of the change in the dielectric constant, in PFM, tunability can be extracted via electrostrictive response. The near-field microwave imaging and PFM provide similar information about dielectric tunability with PFM capable to deliver quantitative information on tunability with a higher spatial resolution close to 15 nm. This is the first time that information about the dielectric tunability is available on such length scales.

  6. Quantitative nanometer-scale mapping of dielectric tunability

    DOE PAGESBeta

    Tselev, Alexander; Klein, Andreas; Gassmann, Juergen; Jesse, Stephen; Li, Qian; Kalinin, Sergei V.; Wisinger, Nina Balke

    2015-08-21

    Two scanning probe microscopy techniques—near-field scanning microwave microscopy (SMM) and piezoresponse force microscopy (PFM)—are used to characterize and image tunability in a thin (Ba,Sr)TiO3 film with nanometer scale spatial resolution. While sMIM allows direct probing of tunability by measurement of the change in the dielectric constant, in PFM, tunability can be extracted via electrostrictive response. The near-field microwave imaging and PFM provide similar information about dielectric tunability with PFM capable to deliver quantitative information on tunability with a higher spatial resolution close to 15 nm. This is the first time that information about the dielectric tunability is available on suchmore » length scales.« less

  7. Mechanical Properties of Materials with Nanometer Scale Microstructures

    SciTech Connect

    William D. Nix

    2004-10-31

    We have been engaged in research on the mechanical properties of materials with nanometer-scale microstructural dimensions. Our attention has been focused on studying the mechanical properties of thin films and interfaces and very small volumes of material. Because the dimensions of thin film samples are small (typically 1 mm in thickness, or less), specialized mechanical testing techniques based on nanoindentation, microbeam bending and dynamic vibration of micromachined structures have been developed and used. Here we report briefly on some of the results we have obtained over the past three years. We also give a summary of all of the dissertations, talks and publications completed on this grant during the past 15 years.

  8. Carbon Nanotubules: Building Blocks for Nanometer-Scale Engineering

    NASA Technical Reports Server (NTRS)

    Sinnott, Susan B.

    1997-01-01

    Proximal probe technology has provided researchers with new ways to investigate and manipulate matter on the nanometer scale. We have studied, through molecular dynamics simulations, using a many-body empirical potential, the indentation of a hydrogen-terminated, diamond (111 ) surface, with a proximal probe tip that consists of an open, hydrogen-terminated, (10,10) carbon nanotubule. The simulations showed that upon indenting 1.8 A, the tubule deforms but returns to its original shape upon retraction. The Young's modulus of the tubule was determined using the predicted Euler buckling force and was found to be comparable to measured and calculated values. In a second series of simulations, an open (10, 10) nanotubule was heated to 4500 K and allowed to close. We find that at this temperature the resulting cap contains numerous imperfections, including some not mentioned previously in the literature.

  9. Magnetic structures of nanometer scale Dy, Cr and Ni

    SciTech Connect

    Fitzsimmons, M.R.; Robinson, R.A.; Lawson, A.C.; Kwei, G.H.; Sickafus, K.E.; Eastman, J.A.; Burkel, E.

    1992-10-01

    Materials composed of nanometer-sized structures are becoming technologically relevant as the sizes of electronic devices approach the nanometer scale. Questions as to the performance and durability of these devices can be partially addressed through the characterization and understanding of the magnetic structures and properties of nanometer-sized materials. The purpose of the present work is to understand the relationship between the microstructure of nanocrystalline materials and their magnetic structures and properties. This paper summarizes three separate experiments: (1) an X-ray diffraction and anomalous absorption (XANES) study of nanocrystalline Dy, (2) neutron diffraction measurements of the magnetic structure of nanocrystalline Cr, and (3) the measurement of the magnetization density of a single twist grain boundary in Ni.

  10. Understanding batteries on the micro- and nanometer scale

    SciTech Connect

    2013-07-22

    In order to understand performance limitations and failure mechanisms of batteries, one has to investigate processes on the micro- and nanometer scale. A typical failure mechanism in lithium metal batteries is dendritic growth. During discharge, lithium is stripped of the anode surface and migrates to the cathode. During charge, lithium is deposited back on the anode. Repeated cycling can result in stripping and re-deposition that roughens the surface. The roughening of the surface changes the electric field and draws more metal to spikes that are beginning to grow. These can grow with tremendous mechanical force, puncture the separator, and directly connect the anode with the cathode which can create an internal short circuit. This can lead to an uncontrolled discharge reaction, which heats the cell and causes additional exothermic reactions leading to what is called thermal runaway. ORNL has developed a new technology called liquid electron microscopy. In a specially designed sample holder micro-chamber with electron-transparent windows, researchers can hold a liquid and take images of structures and particles at nanometer size. It's the first microscope holder of its kind used to investigate the inside of a battery while cycled.

  11. Nanometer Scale Hard/Soft Bilayer Magnetic Antidots.

    PubMed

    Béron, Fanny; Kaidatzis, Andreas; Velo, Murilo F; Arzuza, Luis C C; Palmero, Ester M; Del Real, Rafael P; Niarchos, Dimitrios; Pirota, Kleber R; García-Martín, José Miguel

    2016-12-01

    The effect of arrays of nanometer scale pores on the magnetic properties of thin films has been analyzed. Particularly, we investigated the influence of the out-of-plane magnetization component created by the nanopores on the in-plane magnetic behavior of patterned hard/soft magnetic thin films in antidot morphology. Its influence on the coupling in Co/Py bilayers of few tens of nanometer thick is compared for disordered and ordered antidots of 35-nm diameter. The combination of magneto-optical Kerr effect (MOKE) and first-order reversal curve (FORC) technique allows probing the effects of the induced perpendicular magnetization component on the bilayer magnetic behavior, while magnetic force microscopy (MFM) is used to image it. We found that ordered antidots yield a stronger out-of-plane component than disordered ones, influencing in a similar manner the hard layer global in-plane magnetic behavior if with a thin or without soft layer. However, its influence changes with a thicker soft layer, which may be an indication of a weaker coupling. PMID:26873261

  12. Understanding batteries on the micro- and nanometer scale

    ScienceCinema

    None

    2014-06-03

    In order to understand performance limitations and failure mechanisms of batteries, one has to investigate processes on the micro- and nanometer scale. A typical failure mechanism in lithium metal batteries is dendritic growth. During discharge, lithium is stripped of the anode surface and migrates to the cathode. During charge, lithium is deposited back on the anode. Repeated cycling can result in stripping and re-deposition that roughens the surface. The roughening of the surface changes the electric field and draws more metal to spikes that are beginning to grow. These can grow with tremendous mechanical force, puncture the separator, and directly connect the anode with the cathode which can create an internal short circuit. This can lead to an uncontrolled discharge reaction, which heats the cell and causes additional exothermic reactions leading to what is called thermal runaway. ORNL has developed a new technology called liquid electron microscopy. In a specially designed sample holder micro-chamber with electron-transparent windows, researchers can hold a liquid and take images of structures and particles at nanometer size. It's the first microscope holder of its kind used to investigate the inside of a battery while cycled.

  13. Mechanical properties of materials with nanometer scale microstructures

    SciTech Connect

    Nix, W.D.

    1991-07-01

    For the past two years we have been engaged in a program of research on the mechanical properties of a variety of new materials with nanometer scale microstructures. These materials have been developed recently using vapor phase synthesis techniques and are available in the form of compositionally-modulated (multilayered) thin film materials and ultrafine-grained (nanocrystalline) solids. They have interesting microstructures and mechanical properties that may lead to new applications for these materials. In this report we give a brief summary of some of the results we have obtained to date in the course of this research. Other, more detailed, descriptions of some of this work can be found in the papers that we have published. These are listed at the end of this report along with a listing of the oral presentations we have given. We report briefly on our studies of the elastic properties of metallic multilayered thin films. Using indentation and microbeam deflection techniques, we have found that Au/Ni multilayers do not show supermodulus effects, contrary to some previous reports based on bulge test results. However, we have discovered large and significant substrate interaction stresses in these films which depend systematically on the composition modulation wavelength. We believe that these residual stresses may have led to bulge testing errors which in turn led to erroneous reports of supermodulus effects.

  14. Observing Optical Plasmons on a Single Nanometer Scale

    PubMed Central

    Cohen, Moshik; Shavit, Reuven; Zalevsky, Zeev

    2014-01-01

    The exceptional capability of plasmonic structures to confine light into deep subwavelength volumes has fashioned rapid expansion of interest from both fundamental and applicative perspectives. Surface plasmon nanophotonics enables to investigate light - matter interaction in deep nanoscale and harness electromagnetic and quantum properties of materials, thus opening pathways for tremendous potential applications. However, imaging optical plasmonic waves on a single nanometer scale is yet a substantial challenge mainly due to size and energy considerations. Here, for the first time, we use Kelvin Probe Force Microscopy (KPFM) under optical illumination to image and characterize plasmonic modes. We experimentally demonstrate unprecedented spatial resolution and measurement sensitivity both on the order of a single nanometer. By comparing experimentally obtained images with theoretical calculation results, we show that KPFM maps may provide valuable information on the phase of the optical near field. Additionally, we propose a theoretical model for the relation between surface plasmons and the material workfunction measured by KPFM. Our findings provide the path for using KPFM for high resolution measurements of optical plasmons, prompting the scientific frontier towards quantum plasmonic imaging on submolecular scales. PMID:24556874

  15. Strategies for Probing Nanometer-Scale Electrocatalysts: From Single Particles to Catalyst-Membrane Architectures

    SciTech Connect

    Korzeniewski, Carol

    2014-01-20

    The project primary objectives are to prepare and elucidate the promoting properties of materials that possess high activity for the conversion of hydrogen and related small molecules (water, oxygen, carbon monoxide and methanol) in polymer electrolyte fuel cells. One area of research has focused on the study of catalyst materials. Protocols were developed for probing the structure and benchmarking the activity of Pt and Pt bimetallic nanometer-scale catalyst against Pt single crystal electrode standards. A second area has targeted fuel cell membrane and the advancement of simple methods mainly based on vibrational spectroscopy that can be applied broadly in the study of membrane structure and transport properties. Infrared and Raman methods combined with least-squares data modeling were applied to investigate and assist the design of robust, proton conductive membranes, which resist reactant crossover.

  16. Nanometer-scale flow of molten polyethylene from a heated atomic force microscope tip.

    PubMed

    Felts, Jonathan R; Somnath, Suhas; Ewoldt, Randy H; King, William P

    2012-06-01

    We investigate the nanometer-scale flow of molten polyethylene from a heated atomic force microscope (AFM) cantilever tip during thermal dip-pen nanolithography (tDPN). Polymer nanostructures were written for cantilever tip temperatures and substrate temperatures controlled over the range 100-260 °C and while the tip was either moving with speed 0.5-2.0 µm s(-1) or stationary and heated for 0.1-100 s. We find that polymer flow depends on surface capillary forces and not on shear between tip and substrate. The polymer mass flow rate is sensitive to the temperature-dependent polymer viscosity. The polymer flow is governed by thermal Marangoni forces and non-equilibrium wetting dynamics caused by a solidification front within the feature. PMID:22551550

  17. Nanometer-scale flow of molten polyethylene from a heated atomic force microscope tip

    NASA Astrophysics Data System (ADS)

    Felts, Jonathan R.; Somnath, Suhas; Ewoldt, Randy H.; King, William P.

    2012-06-01

    We investigate the nanometer-scale flow of molten polyethylene from a heated atomic force microscope (AFM) cantilever tip during thermal dip-pen nanolithography (tDPN). Polymer nanostructures were written for cantilever tip temperatures and substrate temperatures controlled over the range 100-260 °C and while the tip was either moving with speed 0.5-2.0 µm s-1 or stationary and heated for 0.1-100 s. We find that polymer flow depends on surface capillary forces and not on shear between tip and substrate. The polymer mass flow rate is sensitive to the temperature-dependent polymer viscosity. The polymer flow is governed by thermal Marangoni forces and non-equilibrium wetting dynamics caused by a solidification front within the feature.

  18. Nanometer-scale free surface flow of molten polyethylene from a heated atomic force microscope tip

    NASA Astrophysics Data System (ADS)

    Ewoldt, Randy; Felts, Jonathan; Somnath, Suhas; King, William

    2012-11-01

    We experimentally investigate nanometer-scale free surface flow of molten polyethylene from a heated atomic force microscope (AFM) cantilever, a nanofabrication process known as thermal dip-pen nanolithography (tDPN). Fluid is deposited from the AFM tip onto non-porous substrates whether the tip is moving or fixed. We find that polymer flow depends on surface capillary forces and not on shear between tip and substrate. The polymer mass flow rate is sensitive to the temperature-dependent polymer viscosity. Additionally, the flow rate increases when a temperature gradient exists between the tip and substrate. We hypothesize that the polymer flow is governed by thermal Marangoni forces and non-equilibrium wetting dynamics caused by a solidification front within the feature.

  19. Decoupling Electrochemical Reaction and Diffusion Processes in Ionically-Conductive Solids on the Nanometer Scale

    SciTech Connect

    Balke, Nina; Jesse, Stephen; Kim, Yoongu; Adamczyk, Leslie A; Ivanov, Ilia N; Dudney, Nancy J; Kalinin, Sergei V

    2010-01-01

    We have developed a scanning probe microscopy approach to explore voltage-controlled ion dynamics in ionically conductive solids and decouple transport and local electrochemical reactivity on the nanometer scale. Electrochemical strain microscopy allows detection of bias-induced ionic motion through the dynamic (0.1-1 MHz) local strain. Spectroscopic modes based on low-frequency ({approx}1 Hz) voltage sweeps allow local ion dynamics to be probed locally. The bias dependence of the hysteretic strain response accessed through first-order reversal curve (FORC) measurements demonstrates that the process is activated at a certain critical voltage and is linear above this voltage everywhere on the surface. This suggests that FORC spectroscopic ESM data separates local electrochemical reaction and transport processes. The relevant parameters such as critical voltage and effective mobility can be extracted for each location and correlated with the microstructure. The evolution of these behaviors with the charging of the amorphous Si anode in a thin-film Li-ion battery is explored. A broad applicability of this method to other ionically conductive systems is predicted.

  20. Decoupling electrochemical reaction and diffusion processes in ionically-conductive solids on the nanometer scale

    SciTech Connect

    Balke, N.; Jesse, S.; Kim, Y.; Adamczyk, L.; Ivanov, I.; Dudney, N. J.; Kalinin, S. V.

    2010-12-28

    We have developed a scanning probe microscopy approach to explore voltage-controlled ion dynamics in ionically conductive solids and decouple transport and local electrochemical reactivity on the nanometer scale. Electrochemical strain microscopy allows detection of bias-induced ionic motion through the dynamic (0.1-1 MHz) local strain. Spectroscopic modes based on low-frequency (~1 Hz) voltage sweeps allow local ion dynamics to be probed locally. The bias dependence of the hysteretic strain response accessed through first-order reversal curve (FORC) measurements demonstrates that the process is activated at a certain critical voltage and is linear above this voltage everywhere on the surface. This suggests that FORC spectroscopic ESM data separates local electrochemical reaction and transport processes. The relevant parameters such as critical voltage and effective mobility can be extracted for each location and correlated with the microstructure. The evolution of these behaviors with the charging of the amorphous Si anode in a thin-film Li-ion battery is explored. A broad applicability of this method to other ionically conductive systems is predicted.

  1. Bioreactor Mass Transport Studies

    NASA Technical Reports Server (NTRS)

    Kleis, Stanley J.; Begley, Cynthia M.

    1997-01-01

    The objectives of the proposed research efforts were to develop both a simulation tool and a series of experiments to provide a quantitative assessment of mass transport in the NASA rotating wall perfused vessel (RWPV) bioreactor to be flown on EDU#2. This effort consisted of a literature review of bioreactor mass transport studies, the extension of an existing scalar transport computer simulation to include production and utilization of the scalar, and the evaluation of experimental techniques for determining mass transport in these vessels. Since mass transport at the cell surface is determined primarily by the relative motion of the cell assemblage and the surrounding fluid, a detailed assessment of the relative motion was conducted. Results of the simulations of the motion of spheres in the RWPV under microgravity conditions are compared with flight data from EDU#1 flown on STS-70. The mass transport across the cell membrane depends upon the environment, the cell type, and the biological state of the cell. Results from a literature review of cell requirements of several scalars are presented. As a first approximation, a model with a uniform spatial distribution of utilization or production was developed and results from these simulations are presented. There were two candidate processes considered for the experimental mass transport evaluations. The first was to measure the dissolution rate of solid or gel beads. The second was to measure the induced fluorescence of beads as a stimulant (for example hydrogen peroxide) is infused into the vessel. Either technique would use video taped images of the process for recording the quantitative results. Results of preliminary tests of these techniques are discussed.

  2. Automated transportable mass spectrometer

    NASA Astrophysics Data System (ADS)

    Echo, M. W.

    1981-09-01

    The need was identified for a mass spectrometer (MS) which can be conveniently transported among several facilities for rapid verification of the isotopic composition of special nuclear material. This requirement for a light weight, transportable MS for U and Pu mass analysis was met by deleting the gas chromograph (GC) portions of a Hewlett-Packard Model 5992 Quadrupole GCMS and substituting a vacuum lock sample entry system. A programmable power supply and vacuum gauge were added and circuitry modifications were made to enable use of the supplied software.

  3. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    SciTech Connect

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  4. Optical spectroscopy at the nanometer scale: Carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yin, Yan

    Resonant Raman scattering (RRS) and photoluminescence (PL) are two important optical methods to understand the underlying physics of carbon nanotubes (CNT). Using a tunable Raman and photoluminescence excitation (PLE) spectroscopy microscope, we are able to measure RRS excitation profiles for isolated CNTs and small ropes suspended in air. Analysis reveals the optical transition energy E22, the broadening eta, and for the first time directly yields the electron-phonon coupling matrix elements | Me-ph| and the electron-photon coupling matrix elements |Me-op|. The electron-phonon coupling is critical to understanding transport and optical phenomenon and yields new insight into nanotube physics. Direct measurement of |Me-ph| is proposed and demonstrated experimentally by combining the first and second harmonics of the radial breathing mode (RBM) Raman scattering profiles. |M e-ph| values are quantitatively measured for individual CNTs in small ropes and isolated in air. The results show that the matrix elements in both cases satisfy S. V. Goupalov and coworker's theory, where | Me-ph|2 = ad2t +ubdtcos 3q2 but with different a and b values. The quantitative value for the isolated CNT is in good agreement with ab initio calculations. The matrix elements |Me-ph| for a CNT in a small rope are only about half of that for an isolated CNT. In addition, |Me-ph| values for other Raman modes, the iTA, LA, D, G- and G+, are also obtained from CNTs in small ropes. G+, which shows strongest coupling (0.030eV) of all measured Raman modes, is also 1.8 times weaker than the calculated value for graphene. Most of the measured CNTs do not exhibit PL and are suspected to be in small ropes. They show 33-93meV E22 red shifts compared to results for CNTs in sodium dodecyl sulfate solution. Such large energy shifts are believed to be due to bundling effects which reduce the band gaps. The one measured CNT with PL, believed to be an individual CNT, only shows a minor red shift 8meV. We find

  5. Mass Transport within Soils

    SciTech Connect

    McKone, Thomas E.

    2009-03-01

    Contaminants in soil can impact human health and the environment through a complex web of interactions. Soils exist where the atmosphere, hydrosphere, geosphere, and biosphere converge. Soil is the thin outer zone of the earth's crust that supports rooted plants and is the product of climate and living organisms acting on rock. A true soil is a mixture of air, water, mineral, and organic components. The relative proportions of these components determine the value of the soil for agricultural and for other human uses. These proportions also determine, to a large extent, how a substance added to soil is transported and/or transformed within the soil (Spositio, 2004). In mass-balance models, soil compartments play a major role, functioning both as reservoirs and as the principal media for transport among air, vegetation, surface water, deeper soil, and ground water (Mackay, 2001). Quantifying the mass transport of chemicals within soil and between soil and atmosphere is important for understanding the role soil plays in controlling fate, transport, and exposure to multimedia pollutants. Soils are characteristically heterogeneous. A trench dug into soil typically reveals several horizontal layers having different colors and textures. As illustrated in Figure 1, these multiple layers are often divided into three major horizons: (1) the A horizon, which encompasses the root zone and contains a high concentration of organic matter; (2) the B horizon, which is unsaturated, lies below the roots of most plants, and contains a much lower organic carbon content; and (3) the C horizon, which is the unsaturated zone of weathered parent rock consisting of bedrock, alluvial material, glacial material, and/or soil of an earlier geological period. Below these three horizons lies the saturated zone - a zone that encompasses the area below ground surface in which all interconnected openings within the geologic media are completely filled with water. Similarly to the unsaturated zone

  6. Survey of plasmonic gaps tuned at sub-nanometer scale in self-assembled arrays

    NASA Astrophysics Data System (ADS)

    Qian, Li-Hua; Yi, Li-Zhi; Wang, Gui-Sheng; Zhang, Chao; Yuan, Song-Liu

    2016-04-01

    Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the optical spectrum and the gap size, the ability to tune these nanoscale gaps at the sub-nanometer scale is particularly desirable. Many nanofabrication methodologies, including electron beam lithography, self-assembly, and focused ion beams, have been tested for creating nanoscale gaps that can deliver significant field enhancement. Here, we survey recent progress in both the reliable creation of nanoscale gaps in nanoparticle arrays using self-assemblies and in the in-situ tuning techniques at the sub-nanometer scale. Precisely tunable gaps, as we expect, will be good candidates for future investigations of surface-enhanced Raman scattering, non-linear optics, and quantum plasmonics.

  7. Formation and properties of 3D metamaterial composites fabricated using nanometer scale laser lithography (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Prokes, Sharka M.; Perkins, Frank K.; Glembocki, Orest J.

    2015-08-01

    Metamaterials designed for the visible or near IR wavelengths require patterning on the nanometer scale. To achieve this, e-beam lithography is used, but it is extremely difficult and can only produce 2D structures. A new alternative technique to produce 2D and 3D structures involves laser fabrication using the Nanoscribe 3D laser lithography system. This is a direct laser writing technique which can form arbitrary 3D nanostructures on the nanometer scale and is based on multi-photon polymerization. We are creating 2D and 3D metamaterials via this technique, and subsequently conformally coating them using Atomic Layer Deposition of oxides and Ag. We will discuss the optical properties of these novel composite structures and their potential for dual resonant metamaterials.

  8. Growth of single diamond crystallites around nanometer-scale silicon wires

    SciTech Connect

    Dennig, P.A.; Liu, H.I.; Stevenson, D.A.; Pease, R.F.W.

    1995-08-14

    Diamond crystallites were nucleated and grown from the vapor phase on silicon substrates previously processed into arrays of nanometer-scale silicon wires. We found that the nanowires did not aid nucleation, and that the nucleation density on the nanowire base was very low ({lt}10{sup 4} cm{sup {minus}2}). Most importantly, we discovered that single diamond crystallites grew around the nanowires, infiltrating the nanowire arrays, forming new composite structures. This discovery clearly shows how inclusions can be trapped in vapor grown diamond crystallites, and challenges the common assumption that growth precursors on the diamond surface are relatively immobile. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  9. Shape Reconstruction Based on a New Blurring Model at the Micro/Nanometer Scale.

    PubMed

    Wei, Yangjie; Wu, Chengdong; Wang, Wenxue

    2016-01-01

    Real-time observation of three-dimensional (3D) information has great significance in nanotechnology. However, normal nanometer scale observation techniques, including transmission electron microscopy (TEM), and scanning probe microscopy (SPM), have some problems to obtain 3D information because they lack non-destructive, intuitive, and fast imaging ability under normal conditions, and optical methods have not widely used in micro/nanometer shape reconstruction due to the practical requirements and the imaging limitations in micro/nano manipulation. In this paper, a high resolution shape reconstruction method based on a new optical blurring model is proposed. Firstly, the heat diffusion physics equation is analyzed and the optical diffraction model is modified to directly explain the basic principles of image blurring resulting from depth variation. Secondly, a blurring imaging model is proposed based on curve fitting of a 4th order polynomial curve. The heat diffusion equations combined with the blurring imaging are introduced, and their solution is transformed into a dynamic optimization problem. Finally, the experiments with a standard nanogrid, an atomic force microscopy (AFM) cantilever and a microlens have been conducted. The experiments prove that the proposed method can reconstruct 3D shapes at the micro/nanometer scale, and the minimal reconstruction error is 3 nm. PMID:26927129

  10. Shape Reconstruction Based on a New Blurring Model at the Micro/Nanometer Scale

    PubMed Central

    Wei, Yangjie; Wu, Chengdong; Wang, Wenxue

    2016-01-01

    Real-time observation of three-dimensional (3D) information has great significance in nanotechnology. However, normal nanometer scale observation techniques, including transmission electron microscopy (TEM), and scanning probe microscopy (SPM), have some problems to obtain 3D information because they lack non-destructive, intuitive, and fast imaging ability under normal conditions, and optical methods have not widely used in micro/nanometer shape reconstruction due to the practical requirements and the imaging limitations in micro/nano manipulation. In this paper, a high resolution shape reconstruction method based on a new optical blurring model is proposed. Firstly, the heat diffusion physics equation is analyzed and the optical diffraction model is modified to directly explain the basic principles of image blurring resulting from depth variation. Secondly, a blurring imaging model is proposed based on curve fitting of a 4th order polynomial curve. The heat diffusion equations combined with the blurring imaging are introduced, and their solution is transformed into a dynamic optimization problem. Finally, the experiments with a standard nanogrid, an atomic force microscopy (AFM) cantilever and a microlens have been conducted. The experiments prove that the proposed method can reconstruct 3D shapes at the micro/nanometer scale, and the minimal reconstruction error is 3 nm. PMID:26927129

  11. Nanometer-scale fabrication of hydrogen silsesquioxane (HSQ) films with post exposure baking.

    PubMed

    Kim, Dong-Hyun; Kang, Se-Koo; Yeom, Geun-Young; Jang, Jae-Hyung

    2013-03-01

    A nanometer-scale grating structure with a 60-nm-wide gap and 200-nm-wide ridge has been successfully demonstrated on a silicon-on-insulator substrate by using a 220-nm-thick hydrogen silsesquioxane (HSQ) negative tone electron beam resist. A post exposure baking (PEB) process and hot development process with low concentration (3.5 wt%) of tetramethylammonium hydroxide (TMAH) solution were introduced to realize the grating pattern. To study the effects of post exposure baking on the HSQ resist, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses were carried out. From the FT-IR and XPS analyses, it was verified that a thin SiO2 with high cross-linked network structure was formed on the HSQ surface during the PEB step. This SiO2 layer prevents the formation of unwanted bonds on the HSQ surface, which results in clearly defined grating structures with a 60-nm-gap and 200-nm-wide-ridge on the 220-nm-thick HSQ resist. The nanometer-scale grating pattern was successfully transfered to the 280-nm-thick silicon layer of a silicon-on-insulator (SOI) substrate by using inductively-coupled-plasma-reactive-ion-etching (ICP-RIE). PMID:23755620

  12. Shape and Effective Spring Constant of Liquid Interfaces Probed at the Nanometer Scale: Finite Size Effects.

    PubMed

    Dupré de Baubigny, Julien; Benzaquen, Michael; Fabié, Laure; Delmas, Mathieu; Aimé, Jean-Pierre; Legros, Marc; Ondarçuhu, Thierry

    2015-09-15

    We investigate the shape and mechanical properties of liquid interfaces down to nanometer scale by atomic force microscopy (AFM) and scanning electron microscopy (SEM) combined with in situ micromanipulation techniques. In both cases, the interface is probed with a cylindrical nanofiber with radius R of the order of 25-100 nm. The effective spring constant of the nanomeniscus oscillated around its equilibrium position is determined by static and frequency-modulation (FM) AFM modes. In the case of an unbounded meniscus, we find that the effective spring constant k is proportional to the surface tension γ of the liquid through k = (0.51 ± 0.06)γ, regardless of the excitation frequency from quasi-static up to 450 kHz. A model based on the equilibrium shape of the meniscus reproduces well the experimental data. Electron microscopy allowed to visualize the meniscus profile around the fiber with a lateral resolution of the order of 10 nm and confirmed its catenary shape. The influence of a lateral confinement of the interface is also investigated. We showed that the lateral extension L of the meniscus influences the effective spring constant following a logarithmic evolution k ∼ 2πγ/ln(L/R) deduced from the model. This comprehensive study of liquid interface properties over more than 4 orders of magnitude in meniscus size shows that advanced FM-AFM and SEM techniques are promising tools for the investigation of mechanical properties of liquids down to nanometer scale. PMID:26295187

  13. Mechanical properties of organic matter in shales mapped at the nanometer scale

    NASA Astrophysics Data System (ADS)

    Eliyahu, M.; Emmanuel, S.; Day-Stirrat, R. J.; Macaulay, C.

    2014-12-01

    The mechanical properties of organic matter strongly influence the way in which shales deform and fracture. However, the response of organic matter to mechanical stresses is not well understood, representing a critical obstacle to assessing oil and gas production in shale formations. Little is known about the mechanical properties of organic matter in fine grained rocks primarily because it often occupies tiny nanometer-scale voids between the mineral grains which cannot be accessed using standard mechanical testing techniques. Here, we report on the use of a new atomic force microscopy technique (PeakForce QNM) to map the mechanical properties of organic and inorganic components at the nanometer scale. We find that the method can identify different phases such as pyrite, quartz, clays, and organic matter. Furthermore, within the organic component Young's modulus values ranged from 0 - 25 GPa; in 3 different samples - all of which come from thermally mature Type II/III source rocks in the dry gas window - a modal value of 15-16 GPa was measured, with additional peaks measured at ≤ 10 GPa. In addition, the maps suggest that some porous organic macerals possess a soft core surrounded by a harder outer shell 50 - 100 nm thick. Our results demonstrate that the method represents a powerful new petrographic tool with which to characterize the mechanical properties of organic-rich sedimentary rocks.

  14. Urban Mass Transportation.

    ERIC Educational Resources Information Center

    Mervine, K. E.

    This bibliography is part of a series of Environmental Resource Packets prepared under a grant from EXXON Education Foundation. The most authoritative and accessible references in the urban transportation field are reviewed. The authors, publisher, point of view, level, and summary are given for each reference. The references are categorized…

  15. Mass transport contamination study

    NASA Technical Reports Server (NTRS)

    Robertson, S. J.

    1972-01-01

    A theoretical analysis was performed to determine the effects of outgassing and waste dumping on the contamination field around an orbiting spacecraft. The spacecraft was assumed to be spherical in shape with the mass flow emitting uniformly from the spherical surface at a constant rate and in a D'Lambertian spatial distribution. The outflow of gases were assumed to be neutrally charged and of a single species with a molecular weight characteristic of a composite of the actual species involved in the mass flow. The theoretical analysis showed that, for outgassing only, less than 1.5 percent of the outgas products will return to the Skylab spacecraft as a result of intermolecular collisions. When the total mass flow from the spacecraft, including waste dumps and reaction control motor firings, was considered, it was estimated that about 30 percent will return to the spacecraft.

  16. Aerobic microbial dolomite at the nanometer scale: Implications for the geologic record

    NASA Astrophysics Data System (ADS)

    Sánchez-Román, Mónica; Vasconcelos, Crisógono; Schmid, Thomas; Dittrich, Maria; McKenzie, Judith A.; Zenobi, Renato; Rivadeneyra, Maria A.

    2008-11-01

    Microbial experiments are the only proven approach to produceexperimental dolomite under Earth's surface conditions. Althoughmicrobial metabolisms are known to induce dolomite precipitationby favoring dolomite growth kinetics, the involvement of microbesin the dolomite nucleation process is poorly understood. Inparticular, the nucleation of microbially mediated dolomiteremains a matter for investigation because the metabolic diversityinvolved in this process has not been fully explored. Hereinwe demonstrate that Halomonas meridiana and Virgibacillus marismortui,two moderately halophilic aerobic bacteria, mediate primaryprecipitation of dolomite at low temperatures (25, 35 °C).This report emphasizes the biomineralogical implications fordolomite formation at the nanometer scale. We describe nucleationof dolomite on nanoglobules in intimate association with thebacterial cell surface. A combination of both laboratory cultureexperiments and natural samples reveals that these nanoglobulestructures may be: (1) the initial step for dolomite nucleation,(2) preserved in the geologic record, and (3) used as microbialtracers through time and/or as a proxy for ancient microbialdolomite, as well as other carbonate minerals.

  17. Field mapping with nanometer-scale resolution for the next generation of electronic devices.

    PubMed

    Cooper, David; de la Peña, Francisco; Béché, Armand; Rouvière, Jean-Luc; Servanton, Germain; Pantel, Roland; Morin, Pierre

    2011-11-01

    In order to improve the performance of today's nanoscaled semiconductor devices, characterization techniques that can provide information about the position and activity of dopant atoms and the strain fields are essential. Here we demonstrate that by using a modern transmission electron microscope it is possible to apply multiple techniques to advanced materials systems in order to provide information about the structure, fields, and composition with nanometer-scale resolution. Off-axis electron holography has been used to map the active dopant potentials in state-of-the-art semiconductor devices with 1 nm resolution. These dopant maps have been compared to electron energy loss spectroscopy maps that show the positions of the dopant atoms. The strain fields in the devices have been measured by both dark field electron holography and nanobeam electron diffraction. PMID:21972919

  18. Optical sensing of current dynamics in organic light-emitting devices at the nanometer scale.

    PubMed

    Nothaft, Maximilian; Höhla, Steffen; Nicolet, Aurélien; Jelezko, Fedor; Frühauf, Norbert; Pflaum, Jens; Wrachtrup, Jörg

    2011-10-01

    Photoluminescence quenching of single dibenzoterrylene (DBT) dye molecules in a polymeric organic light-emitting diode was utilized to analyze the current dynamics at nanometer resolution. The quenching mechanism of single DBT molecules results from an increase in the triplet-state population induced by charge carrier recombination on individual guest molecules. As a consequence of the long triplet-state relaxation time, its population results in a reduced photoluminescence of the dispersed fluorescent dyes. From the decrease in photoluminescence together with photon correlation measurements, we could quantify the local current density and its time-dependent evolution in the vicinity of the single-molecule probe. This optical technique establishes a non-invasive approach to map the time-resolved current density in organic light-emitting diodes on the nanometer scale. PMID:21830293

  19. Nanometer-scale surface modification of Ti6Al4V alloy for orthopedic applications.

    PubMed

    Xie, Jianhui; Luan, Ben Li

    2008-01-01

    This communication presents a novel technology to enhance the biocompatibility of bioinert Ti6Al4V alloy as implant materials for orthopaedic application. The surface of Ti6Al4V alloy was electrochemically activated in NaOH solution to create a porous structure with nanometer topographic features and an alkaline environment, thus promoting the formation of bone-like hydroxyapatite coating and enhancing the bonding strength of the coating. This innovative activation process was proved to be effective and essential. The activated surface was confirmed to be pure TiO2 and the formed coating was characterized of pure hydroxyapatite with a nanometer-scaled grain size structure by means of XPS, FESEM/SEM/EDX, XRD, and TEM techniques. PMID:17600328

  20. Toward Nanometer-Scale Optical Photolithography: Utilizing the Near-Field of Bowtie Optical Nanoantennas

    PubMed Central

    Sundaramurthy, Arvind; Kino, Gordon S.; Schuck, P. James; Conley, Nicholas R.; Fromm, David P.; Moerner, W. E.

    2006-01-01

    Optically resonant metallic bowtie nanoantennas are utilized as fabrication tools for the first time, resulting in the production of polymer resist nanostructures <30 nm in diameter at record low incident multiphoton energy densities. The nanofabrication is accomplished via nonlinear photopolymerization, which is initiated by the enhanced, confined optical fields surrounding the nanoantenna. The position, size, and shape of the resist nanostructures directly correlate with rigorous finite-difference time-domain computations of the field distribution, providing a nanometer-scale measurement of the actual field confinement offered by single optical nanoantennas. In addition, the size of the photoresist regions yields strong upper bounds on photoacid diffusion and resist resolution in SU-8, demonstrating a technique that can be generalized to the study of many current and yet-to-be-developed photoresist systems. PMID:16522022

  1. Process Control in Laser Material Processing for the Micro and Nanometer Scale Domains

    NASA Astrophysics Data System (ADS)

    Helvajian, Henry

    An array of laser material processing techniques is presented for fabricating structures in the micro and nanometer scale length domains. For the past 20 years, processes have been demonstrated where the use of the inherent properties of lasers has led to increased fidelity in the processing of materials. These demonstrated processes often use inventive approaches that rely on derivative aspects of established primary principles that govern laser/material interaction phenomena. The intent of this overview is to explore the next generation of processes and techniques that could be applied in industry because of the need for better precision, higher resolution, smaller feature size, true 3D fabrication, and higher piece-part fabrication throughput.

  2. Imaging of Optoelectronic Processes in Nanometer-Scale Structures and Composites

    NASA Astrophysics Data System (ADS)

    Adams, David M.

    2001-03-01

    There is growing interest in the underlying physical processes in optoelectronic devices based on composites of organic and inorganic electronic materials, including low-cost large-area solid-state solar cell and light emitting devices, photodetectors, and optical memories. Such devices are often thin-film multilayer structures involving nanostructured polymeric and/or crystalline organic layers and inorganic layers supported on conducting/transparent indium tin oxide glass electrodes. The unique electrooptic behavior of these devices and essential physical processes such as charge injection/separation at interfaces, charge and exciton mobilities, exciton decay processes, and exciton/charge-carrier interactions are often intimately controlled by the detailed nanostructured morphologies of the system. There is a need for experimental tools that allow for imaging (spatial resolution) of the physical properties and processes associated with nanometer scale structures. Ideally, simultaneous imaging of the layer morphology and physical processes would ultimately allow for a direct correlation of morphology and device physics in a functional device, device prototype, or isolated nanostructure. Nanometer scale structures are expected to impact broad areas of electronics and optics technology. The realization of the technological applications requires a greater understanding of how nanostructures are synthesized and fabricated and importantly requires a greater understanding of the intrinsic and potentially unique physical properties of nanostructures. Here we present recent results where two complimentary new methods are used to spatially and temporally resolve optoelectronic properties and processes in nanostructured thin films. Electric field modulated near-field scanning optical microscopy (NSOM) and light-modulated scanning electrostatic potential microscopy (SEPM) are used to investigate self-organizing liquid crystalline molecular semiconductors and photoconductors

  3. Nanometer-Scale Pore Characteristics of Lacustrine Shale, Songliao Basin, NE China

    PubMed Central

    Wang, Min; Yang, Jinxiu; Wang, Zhiwei; Lu, Shuangfang

    2015-01-01

    In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale pores or fractures, so the pore types and PSDs (pore size distributions) play a major role in the shale oil occurrence (free or absorbed state), amount of oil, and flow features. The pore types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale pores and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope) observations, low pressure CO2 and N2 adsorption, and high-pressure mercury injection experiments. Analysis results indicate that: (1) Pore types in the lacustrine shale include inter-matrix pores, intergranular pores, organic matter pores, and dissolution pores, and these pores are dominated by mesopores and micropores; (2) There is no apparent correlation between pore volumes and clay content, however, a weak negative correlation is present between total pore volume and carbonate content; (3) Pores in lacustrine shale are well developed when the organic matter maturity (Ro) is >1.0% and the pore volume is positively correlated with the TOC (total organic carbon) content. The statistical results suggest that oil in lacustrine shale mainly occurs in pores with diameters larger than 40 nm. However, more research is needed to determine whether this minimum pore diameter for oil occurrence in lacustrine shale is widely applicable. PMID:26285123

  4. Nanometer-Scale Pore Characteristics of Lacustrine Shale, Songliao Basin, NE China.

    PubMed

    Wang, Min; Yang, Jinxiu; Wang, Zhiwei; Lu, Shuangfang

    2015-01-01

    In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale pores or fractures, so the pore types and PSDs (pore size distributions) play a major role in the shale oil occurrence (free or absorbed state), amount of oil, and flow features. The pore types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale pores and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope) observations, low pressure CO2 and N2 adsorption, and high-pressure mercury injection experiments. Analysis results indicate that: (1) Pore types in the lacustrine shale include inter-matrix pores, intergranular pores, organic matter pores, and dissolution pores, and these pores are dominated by mesopores and micropores; (2) There is no apparent correlation between pore volumes and clay content, however, a weak negative correlation is present between total pore volume and carbonate content; (3) Pores in lacustrine shale are well developed when the organic matter maturity (Ro) is >1.0% and the pore volume is positively correlated with the TOC (total organic carbon) content. The statistical results suggest that oil in lacustrine shale mainly occurs in pores with diameters larger than 40 nm. However, more research is needed to determine whether this minimum pore diameter for oil occurrence in lacustrine shale is widely applicable. PMID:26285123

  5. Superhydrophilic TiO2 thin film by nanometer scale surface roughness and dangling bonds

    NASA Astrophysics Data System (ADS)

    Bharti, Bandna; Kumar, Santosh; Kumar, Rajesh

    2016-02-01

    A remarkable enhancement in the hydrophilic nature of titanium dioxide (TiO2) films is obtained by surface modification in DC-glow discharge plasma. Thin transparent TiO2 films were coated on glass substrate by sol-gel dip coating method, and exposed in DC-glow discharge plasma. The plasma exposed TiO2 film exhibited a significant change in its wetting property contact angle, which is a representative of wetting property, has reduced to considerable limits 3.02° and 1.85° from its initial value 54.40° and 48.82° for deionized water and ethylene glycol, respectively. It is elucidated that the hydrophilic property of plasma exposed TiO2 films dependent mainly upon nanometer scale surface roughness. Variation, from 4.6 nm to 19.8 nm, in the film surface roughness with exposure time was observed by atomic force microscopy (AFM). Analysis of variation in the values of contact angle and surface roughness with increasing plasma exposure time reveal that the surface roughness is the main factor which makes the modified TiO2 film superhydrophilic. However, a contribution of change in the surface states, to the hydrophilic property, is also observed for small values of the plasma exposure time. Based upon nanometer scale surface roughness and dangling bonds, a variation in the surface energy of TiO2 film from 49.38 to 88.92 mJ/m2 is also observed. X-ray photoelectron spectroscopy (XPS) results show change in the surface states of titanium and oxygen. The observed antifogging properties are the direct results of the development of the superhydrophilic wetting characteristics to TiO2 films.

  6. Laser velocimetry for measurement of non-sinusoidal vibration in sub-nanometer scale without lock-in amplifiers

    NASA Astrophysics Data System (ADS)

    Chen, How-foo; Lin, Rung-Fu; Chiang, Wei-Lun

    2015-08-01

    Laser velocimetry capable of measuring nanoscale motion or displacement normal to vibrational surface is always important in industry and scientific applications. However, measurement sensitivity down to sub-nanometer scale is always a challenge, and utilization of lock-in amplifiers is unavoidable. Measurement is then also limited to single-point detection. Here we report a laser Doppler velocimetry capable of non-contact detection in sub-nanometer scale down to sub-Hertz frequency in a Mach-Zehnder configuration without lock-in amplifiers. Environment perturbation in tens of nanometer scale can be removed by empirical mode decomposition. Lack of lock-in amplifiers promises this technology not limited to single-point detection.

  7. Nanometer-scale manipulator and ultrasonic cutter using an atomic force microscope controlled by a haptic device

    NASA Astrophysics Data System (ADS)

    Iwata, F.; Kawanishi, S.; Sasaki, A.; Aoyama, H.; Ushiki, T.

    2008-10-01

    We describe a nanometer-scale manipulatoion and cutting method using ultrasonic oscillation scratching. The system is based on a modified atomic force microscope (AFM) coupled with a haptic device as a human interface. By handling the haptic device, the operator can directly move the AFM probe to manipulate nanometer scale objects and cut a surface while feeling the reaction from the surface in his or her fingers. As for manipulation using the system, nanometer-scale spheres were controllably moved by feeling the sensation of the AFM probe touching the spheres. As for cutting performance, the samples were prepared on an AT-cut quartz crystal resonator (QCR) set on an AFM sample holder. The QCR oscillates at its resonance frequency (9 MHz) with an amplitude of a few nanometers. Thus it is possible to cut the sample surface smoothly by the interaction between the AFM probe and the oscillating surface, even when the samples are viscoelastics such as polymers and biological samples. The ultrasonic nano-manipulation and cutting system would be a very useful and effective tool in the fields of nanometer-scale engineering and biological sciences.

  8. Virtual rough samples to test 3D nanometer-scale scanning electron microscopy stereo photogrammetry

    NASA Astrophysics Data System (ADS)

    Villarrubia, J. S.; Tondare, V. N.; Vladár, A. E.

    2016-03-01

    The combination of scanning electron microscopy for high spatial resolution, images from multiple angles to provide 3D information, and commercially available stereo photogrammetry software for 3D reconstruction offers promise for nanometer-scale dimensional metrology in 3D. A method is described to test 3D photogrammetry software by the use of virtual samples—mathematical samples from which simulated images are made for use as inputs to the software under test. The virtual sample is constructed by wrapping a rough skin with any desired power spectral density around a smooth near-trapezoidal line with rounded top corners. Reconstruction is performed with images simulated from different angular viewpoints. The software's reconstructed 3D model is then compared to the known geometry of the virtual sample. Three commercial photogrammetry software packages were tested. Two of them produced results for line height and width that were within close to 1 nm of the correct values. All of the packages exhibited some difficulty in reconstructing details of the surface roughness.

  9. Nanometer Scale Titanium Surface Texturing Are Detected by Signaling Pathways Involving Transient FAK and Src Activations

    PubMed Central

    Zambuzzi, Willian F.; Bonfante, Estevam A.; Jimbo, Ryo; Hayashi, Mariko; Andersson, Martin; Alves, Gutemberg; Takamori, Esther R.; Beltrão, Paulo J.; Coelho, Paulo G.; Granjeiro, José M.

    2014-01-01

    Background It is known that physico/chemical alterations on biomaterial surfaces have the capability to modulate cellular behavior, affecting early tissue repair. Such surface modifications are aimed to improve early healing response and, clinically, offer the possibility to shorten the time from implant placement to functional loading. Since FAK and Src are intracellular proteins able to predict the quality of osteoblast adhesion, this study evaluated the osteoblast behavior in response to nanometer scale titanium surface texturing by monitoring FAK and Src phosphorylations. Methodology Four engineered titanium surfaces were used for the study: machined (M), dual acid-etched (DAA), resorbable media microblasted and acid-etched (MBAA), and acid-etch microblasted (AAMB). Surfaces were characterized by scanning electron microscopy, interferometry, atomic force microscopy, x-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. Thereafter, those 4 samples were used to evaluate their cytotoxicity and interference on FAK and Src phosphorylations. Both Src and FAK were investigated by using specific antibody against specific phosphorylation sites. Principal Findings The results showed that both FAK and Src activations were differently modulated as a function of titanium surfaces physico/chemical configuration and protein adsorption. Conclusions It can be suggested that signaling pathways involving both FAK and Src could provide biomarkers to predict osteoblast adhesion onto different surfaces. PMID:24999733

  10. Nanometer-scale ionic reservoir based on ion-responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Kazakov, Sergey V.; Kaholek, Marian; Levon, Kalle

    2002-07-01

    The applicability of the concept of ionic reservoir for the description of hydrogel behavior was demonstrated by potentiometric titration of poly(N-isopropylacrylamide-co-1- vinylimidazole) hydrogel suspension. Four different regions of pH-changes of the microgel suspensions were identified on the titration curve in comparison with pure water. Particularly, at 10.5>pH>6.5 a hydrogel accumulates or releases H+ and Cl- ions without significant swelling/deswelling whereas at 6.5>pH>4 the storage of the ions occurs both due to their binding with ionizable groups on polymer network and due to strong swelling. The mechanical response of hydrogel (swelling/deswelling) is assumed to be a faster process than the electrochemical response (equilibration of ion concentrations interior and exterior to the hydrogel). The size of hydrogel spheres should be diminished to fasten an ionic reservoir response of the hydrogel. A novel protocol for preparation of polymer hydrogel spherical particles on a nanometer scale (nanogels) has been developed. Temperature- and pH-sensitive nanogels were detected and characterized by the dynamic light scattering technique and atomic force microscopy. Ptoentiometric titration of the obtained nanogels shows that the decrease in the ionic reservoir size gains the efficiency and, presumably, the rate of the electrochemical response. These findings indicate the necessity of time-resolved pH-measurements of the hydrogel suspensions for the characterization of the rate of the solute diffusion through the gel/water surface.

  11. Nanometer-scale imaging and pore-scale fluid flow modeling inchalk

    SciTech Connect

    Tomutsa, Liviu; Silin, Dmitriy; Radmilovich, Velimir

    2005-08-23

    For many rocks of high economic interest such as chalk,diatomite, tight gas sands or coal, nanometer scale resolution is neededto resolve the 3D-pore structure, which controls the flow and trapping offluids in the rocks. Such resolutions cannot be achieved with existingtomographic technologies. A new 3D imaging method, based on serialsectioning and using the Focused Ion Beam (FIB) technology has beendeveloped. FIB allows for the milling of layers as thin as 10 nanometersby using accelerated Ga+ ions to sputter atoms from the sample surface.After each milling step, as a new surface is exposed, a 2D image of thissurface is generated. Next, the 2D images are stacked to reconstruct the3D pore or grain structure. Resolutions as high as 10 nm are achievableusing this technique. A new image processing method uses directmorphological analysis of the pore space to characterize thepetrophysical properties of diverse formations. In addition to estimationof the petrophysical properties (porosity, permeability, relativepermeability and capillary pressures), the method is used for simulationof fluid displacement processes, such as those encountered in variousimproved oil recovery (IOR) approaches. Computed with the new methodcapillary pressure curves are in good agreement with laboratory data. Themethod has also been applied for visualization of the fluid distributionat various saturations from the new FIB data.

  12. Ultra-high density single nanometer-scale anodic alumina nanofibers fabricated by pyrophosphoric acid anodizing.

    PubMed

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O

    2014-01-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (10(10) nanofibers/cm(2)) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices. PMID:25491282

  13. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    NASA Astrophysics Data System (ADS)

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-12-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

  14. Nanometer Scale Manipulation of Pristine and Functionalized Freestanding Graphene Using Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Ackerman, Matthew

    Over the past ten years the 2D material graphene has attracted an enourmous amount of attention from researchers from across diciplines and all over the world. Many of its outstanding electronic properties are present only when it is not interacting with a substrate but is instead freestanding. In this work I demonstrate that pristine and functionalized freestanding graphene can be imaged using a scanning tunneling microscope (STM) and that imaging a flexible 2D surface is fundamentally different from imaging a bulk material due to the attraction between the STM tip and the sample. This attraction can be used to manipulate the graphene sample on atomic and even nanometer scales. I first show that the electrostatic attraction between the tip and sample during imaging results in enhanced corrugation in the image. Next, I introduce constant-current spectroscopy measurements and demonstrate the ability to perpendicularly displace the graphene sheet at a single point over a range of tens of nanometers. An electrostatic model is then developed which characterizes the electrostatic force that is used to displace the sheet. Finally, STM images and spectroscopy measurements, along with electron microscope images and molecular dynamics simulations, are used to characterize freestanding graphene sheets functionalized with platinum nanoparticles. It is shown that the platinum particles are self-organized but are not encapsulated by the graphene. Instead the nanoparticles are anchored to the sheet by a small number of covalent bonds. In the future the techniques shown here could be used to characterize other functionalized graphene systems.

  15. Significant enhancement of magnetoresistance with the reduction of particle size in nanometer scale

    PubMed Central

    Das, Kalipada; Dasgupta, P.; Poddar, A.; Das, I.

    2016-01-01

    The Physics of materials with large magnetoresistance (MR), defined as the percentage change of electrical resistance with the application of external magnetic field, has been an active field of research for quite some times. In addition to the fundamental interest, large MR has widespread application that includes the field of magnetic field sensor technology. New materials with large MR is interesting. However it is more appealing to vast scientific community if a method describe to achieve many fold enhancement of MR of already known materials. Our study on several manganite samples [La1−xCaxMnO3 (x = 0.52, 0.54, 0.55)] illustrates the method of significant enhancement of MR with the reduction of the particle size in nanometer scale. Our experimentally observed results are explained by considering model consisted of a charge ordered antiferromagnetic core and a shell having short range ferromagnetic correlation between the uncompensated surface spins in nanoscale regime. The ferromagnetic fractions obtained theoretically in the nanoparticles has been shown to be in the good agreement with the experimental results. The method of several orders of magnitude improvement of the magnetoresistive property will have enormous potential for magnetic field sensor technology. PMID:26837285

  16. Probing Rubber Cross-Linking Generation of Industrial Polymer Networks at Nanometer Scale.

    PubMed

    Gabrielle, Brice; Gomez, Emmanuel; Korb, Jean-Pierre

    2016-06-23

    We present improved analyses of rheometric torque measurements as well as (1)H double-quantum (DQ) nuclear magnetic resonance (NMR) buildup data on polymer networks of industrial compounds. This latter DQ NMR analysis allows finding the distribution of an orientation order parameter (Dres) resulting from the noncomplete averaging of proton dipole-dipole couplings within the cross-linked polymer chains. We investigate the influence of the formulation (filler and vulcanization systems) as well as the process (curing temperature) ending to the final polymer network. We show that DQ NMR follows the generation of the polymer network during the vulcanization process from a heterogeneous network to a very homogeneous one. The time variations of microscopic Dres and macroscopic rheometric torques present power-law behaviors above a threshold time scale with characteristic exponents of the percolation theory. We observe also a very good linear correlation between the kinetics of Dres and rheometric data routinely performed in industry. All these observations confirm the description of the polymer network generation as a critical phenomenon. On the basis of all these results, we believe that DQ NMR could become a valuable tool for investigating in situ the cross-linking of industrial polymer networks at the nanometer scale. PMID:27254797

  17. Interface characterization of nanometer scale CdS buffer layer in chalcopyrite solar cell

    NASA Astrophysics Data System (ADS)

    Lin, Shih-Hung; Cheng, Tzu-Huan

    2016-06-01

    The buffer layer of a chalcopyrite solar cell plays an important role in optical responses of open circuit voltage (V oc) and short circuit current (J sc). A CdS buffer layer is applicable on the nanometer scale owing to its high carrier concentration and n-type semiconductor behavior in chalcopyrite solar cells. The thin buffer layer also contributes to the passivation of the absorber surface to reduce defect recombination loss. Non-destructive metrological parameters such as photoluminescence (PL) intensity, external quantum efficiency (EQE), and depth-resolved photovoltage are used to characterize the interface quality of CdS/chalcopyrite. The defects and dangling bonds at the absorber surface will cause interface recombination and reduce the cell performance in build-in voltage distribution. Post annealing can improve Cd ion diffusion from the buffer layer to the absorber surface and reduce the density of defects and dangling bonds. After thermal annealing, the EQE, PL intensity, and minority carrier lifetime are improved.

  18. Thermal and ultrasonic influence in the formation of nanometer scale hydroxyapatite bio-ceramic

    PubMed Central

    Poinern, GJE; Brundavanam, R; Le, X Thi; Djordjevic, S; Prokic, M; Fawcett, D

    2011-01-01

    Hydroxyapatite (HAP) is a widely used biocompatible ceramic in many biomedical applications and devices. Currently nanometer-scale forms of HAP are being intensely investigated due to their close similarity to the inorganic mineral component of the natural bone matrix. In this study nano-HAP was prepared via a wet precipitation method using Ca(NO3)2 and KH2PO4 as the main reactants and NH4OH as the precipitator under ultrasonic irradiation. The Ca/P ratio was set at 1.67 and the pH was maintained at 9 during the synthesis process. The influence of the thermal treatment was investigated by using two thermal treatment processes to produce ultrafine nano-HAP powders. In the first heat treatment, a conventional radiant tube furnace was used to produce nano-particles with an average size of approximately 30 nm in diameter, while the second thermal treatment used a microwave-based technique to produce particles with an average diameter of 36 nm. The crystalline structure and morphology of all nanoparticle powders produced were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Both thermal techniques effectively produced ultrafine powders with similar crystalline structure, morphology and particle sizes. PMID:22114473

  19. Mechanical properties of materials with nanometer scale microstructures. Progress report, 1 April 1989 to Present

    SciTech Connect

    Nix, W.D.

    1991-07-01

    For the past two years we have been engaged in a program of research on the mechanical properties of a variety of new materials with nanometer scale microstructures. These materials have been developed recently using vapor phase synthesis techniques and are available in the form of compositionally-modulated (multilayered) thin film materials and ultrafine-grained (nanocrystalline) solids. They have interesting microstructures and mechanical properties that may lead to new applications for these materials. In this report we give a brief summary of some of the results we have obtained to date in the course of this research. Other, more detailed, descriptions of some of this work can be found in the papers that we have published. These are listed at the end of this report along with a listing of the oral presentations we have given. We report briefly on our studies of the elastic properties of metallic multilayered thin films. Using indentation and microbeam deflection techniques, we have found that Au/Ni multilayers do not show supermodulus effects, contrary to some previous reports based on bulge test results. However, we have discovered large and significant substrate interaction stresses in these films which depend systematically on the composition modulation wavelength. We believe that these residual stresses may have led to bulge testing errors which in turn led to erroneous reports of supermodulus effects.

  20. Positive feedback can lead to dynamic nanometer-scale clustering on cell membranes

    NASA Astrophysics Data System (ADS)

    Wehrens, Martijn; ten Wolde, Pieter Rein; Mugler, Andrew

    2014-11-01

    Clustering of molecules on biological membranes is a widely observed phenomenon. A key example is the clustering of the oncoprotein Ras, which is known to be important for signal transduction in mammalian cells. Yet, the mechanism by which Ras clusters form and are maintained remains unclear. Recently, it has been discovered that activated Ras promotes further Ras activation. Here we show using particle-based simulation that this positive feedback is sufficient to produce persistent clusters of active Ras molecules at the nanometer scale via a dynamic nucleation mechanism. Furthermore, we find that our cluster statistics are consistent with experimental observations of the Ras system. Interestingly, we show that our model does not support a Turing regime of macroscopic reaction-diffusion patterning, and therefore that the clustering we observe is a purely stochastic effect, arising from the coupling of positive feedback with the discrete nature of individual molecules. These results underscore the importance of stochastic and dynamic properties of reaction diffusion systems for biological behavior.

  1. Significant enhancement of magnetoresistance with the reduction of particle size in nanometer scale.

    PubMed

    Das, Kalipada; Dasgupta, P; Poddar, A; Das, I

    2016-01-01

    The Physics of materials with large magnetoresistance (MR), defined as the percentage change of electrical resistance with the application of external magnetic field, has been an active field of research for quite some times. In addition to the fundamental interest, large MR has widespread application that includes the field of magnetic field sensor technology. New materials with large MR is interesting. However it is more appealing to vast scientific community if a method describe to achieve many fold enhancement of MR of already known materials. Our study on several manganite samples [La(1-x)Ca(x)MnO3 (x = 0.52, 0.54, 0.55)] illustrates the method of significant enhancement of MR with the reduction of the particle size in nanometer scale. Our experimentally observed results are explained by considering model consisted of a charge ordered antiferromagnetic core and a shell having short range ferromagnetic correlation between the uncompensated surface spins in nanoscale regime. The ferromagnetic fractions obtained theoretically in the nanoparticles has been shown to be in the good agreement with the experimental results. The method of several orders of magnitude improvement of the magnetoresistive property will have enormous potential for magnetic field sensor technology. PMID:26837285

  2. Selenate and Selenite Reduction by Nanometer-Scale Zerovalent Iron Particles

    NASA Astrophysics Data System (ADS)

    Olegario, J. T.; Yee, N. Y.; Manning, B. A.

    2007-12-01

    Selenium oxyanions can be present in agricultural drainage waters, coal mining effluent, and as fission products in radioactive wastes. The objective of this work was to evaluate the effectiveness of both nanometer scale zerovalent iron (nano-Fe) and 100 mesh Fe filings for reduction and immobilization of aqueous selenate Se(VI) and selenite Se(IV). The uptake of Se(VI) and Se(IV) using batch equilibrium, kinetics, and X-ray absorption spectroscopic (XAS) techniques was investigated. In addition, a thorough investigation of the solid phase corrosion products by X-ray diffraction was conducted. The crystalline corrosion product was similar to magnetite, though some distinct differences in the XRD results were noted between Se(IV)- and Se(VI)-treated samples. Application of quantitative X-ray absorption near edge spectroscopy (XANES) revealed that both Se(VI) and Se(IV) were reduced to a mixture of elemental Se(0) plus iron(II) selenide (Se(-II)). The Se local atomic structure in Se(VI)- and Se(IV)-treated nano-Fe was determined using extended x-ray absorption fine structure spectroscopy (EXAFS) and a Se-Se interatomic distance of 2.44 angstroms was revealed. This work suggests that nano-Fe is an efficient material for removing dissolved Se(VI) and Se(IV) from waste waters by formation of an insoluble, reduced FeSe product.

  3. Positive feedback can lead to dynamic nanometer-scale clustering on cell membranes

    SciTech Connect

    Wehrens, Martijn; Rein ten Wolde, Pieter; Mugler, Andrew

    2014-11-28

    Clustering of molecules on biological membranes is a widely observed phenomenon. A key example is the clustering of the oncoprotein Ras, which is known to be important for signal transduction in mammalian cells. Yet, the mechanism by which Ras clusters form and are maintained remains unclear. Recently, it has been discovered that activated Ras promotes further Ras activation. Here we show using particle-based simulation that this positive feedback is sufficient to produce persistent clusters of active Ras molecules at the nanometer scale via a dynamic nucleation mechanism. Furthermore, we find that our cluster statistics are consistent with experimental observations of the Ras system. Interestingly, we show that our model does not support a Turing regime of macroscopic reaction-diffusion patterning, and therefore that the clustering we observe is a purely stochastic effect, arising from the coupling of positive feedback with the discrete nature of individual molecules. These results underscore the importance of stochastic and dynamic properties of reaction diffusion systems for biological behavior.

  4. Significant enhancement of magnetoresistance with the reduction of particle size in nanometer scale

    NASA Astrophysics Data System (ADS)

    Das, Kalipada; Dasgupta, P.; Poddar, A.; Das, I.

    2016-02-01

    The Physics of materials with large magnetoresistance (MR), defined as the percentage change of electrical resistance with the application of external magnetic field, has been an active field of research for quite some times. In addition to the fundamental interest, large MR has widespread application that includes the field of magnetic field sensor technology. New materials with large MR is interesting. However it is more appealing to vast scientific community if a method describe to achieve many fold enhancement of MR of already known materials. Our study on several manganite samples [La1-xCaxMnO3 (x = 0.52, 0.54, 0.55)] illustrates the method of significant enhancement of MR with the reduction of the particle size in nanometer scale. Our experimentally observed results are explained by considering model consisted of a charge ordered antiferromagnetic core and a shell having short range ferromagnetic correlation between the uncompensated surface spins in nanoscale regime. The ferromagnetic fractions obtained theoretically in the nanoparticles has been shown to be in the good agreement with the experimental results. The method of several orders of magnitude improvement of the magnetoresistive property will have enormous potential for magnetic field sensor technology.

  5. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    PubMed Central

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-01-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices. PMID:25491282

  6. Three-dimensional integrated circuits for lab-on-chip dielectrophoresis of nanometer scale particles

    NASA Astrophysics Data System (ADS)

    Dickerson, Samuel J.; Noyola, Arnaldo J.; Levitan, Steven P.; Chiarulli, Donald M.

    2007-01-01

    In this paper, we present a mixed-technology micro-system for electronically manipulating and optically detecting virusscale particles in fluids that is designed using 3D integrated circuit technology. During the 3D fabrication process, the top-most chip tier is assembled upside down and the substrate material is removed. This places the polysilicon layer, which is used to create geometries with the process' minimum feature size, in close proximity to a fluid channel etched into the top of the stack. By taking advantage of these processing features inherent to "3D chip-stacking" technology, we create electrode arrays that have a gap spacing of 270 nm. Using 3D CMOS technology also provides the ability to densely integrate analog and digital control circuitry for the electrodes by using the additional levels of the chip stack. We show simulations of the system with a physical model of a Kaposi's sarcoma-associated herpes virus, which has a radius of approximately 125 nm, being dielectrophoretically arranged into striped patterns. We also discuss how these striped patterns of trapped nanometer scale particles create an effective diffraction grating which can then be sensed with macro-scale optical techniques.

  7. Real-Time Imaging of Plant Cell Wall Structure at Nanometer Scale, with Respect to Cellulase Accessibility and Degradation Kinetics (Presentation)

    SciTech Connect

    Ding, S. Y.

    2012-05-01

    Presentation on real-time imaging of plant cell wall structure at nanometer scale. Objectives are to develop tools to measure biomass at the nanometer scale; elucidate the molecular bases of biomass deconstruction; and identify factors that affect the conversion efficiency of biomass-to-biofuels.

  8. Nanometer-scale characterization of exceptionally preserved bacterial fossils in Paleocene phosphorites from Ouled Abdoun (Morocco).

    PubMed

    Cosmidis, J; Benzerara, K; Gheerbrant, E; Estève, I; Bouya, B; Amaghzaz, M

    2013-03-01

    Micrometer-sized spherical and rod-shaped forms have been reported in many phosphorites and often interpreted as microbes fossilized by apatite, based on their morphologic resemblance with modern bacteria inferred by scanning electron microscopy (SEM) observations. This interpretation supports models involving bacteria in the formation of phosphorites. Here, we studied a phosphatic coprolite of Paleocene age originating from the Ouled Abdoun phosphate basin (Morocco) down to the nanometer-scale using focused ion beam milling, transmission electron microscopy (TEM), and scanning transmission x-ray microscopy (STXM) coupled with x-ray absorption near-edge structure spectroscopy (XANES). The coprolite, exclusively composed of francolite (a carbonate-fluroapatite), is formed by the accumulation of spherical objects, delimited by a thin envelope, and whose apparent diameters are between 0.5 and 3 μm. The envelope of the spheres is composed of a continuous crown dense to electrons, which measures 20-40 nm in thickness. It is surrounded by two thinner layers that are more porous and transparent to electrons and enriched in organic carbon. The observed spherical objects are very similar with bacteria encrusting in hydroxyapatite as observed in laboratory experiments. We suggest that they are Gram-negative bacteria fossilized by francolite, the precipitation of which started within the periplasm of the cells. We discuss the role of bacteria in the fossilization mechanism and propose that they could have played an active role in the formation of francolite. This study shows that ancient phosphorites can contain fossil biological subcellular structures as fine as a bacterial periplasm. Moreover, we demonstrate that while morphological information provided by SEM analyses is valuable, the use of additional nanoscale analyses is a powerful approach to help inferring the biogenicity of biomorphs found in phosphorites. A more systematic use of this approach could considerably

  9. Magnetic characterization of noninteracting, randomly oriented, nanometer-scale ferrimagnetic particles

    NASA Astrophysics Data System (ADS)

    Cao, Changqian; Tian, Lanxiang; Liu, Qingsong; Liu, Weifeng; Chen, Guanjun; Pan, Yongxin

    2010-07-01

    Studying the magnetic properties of ultrafine nanometer-scale ferrimagnetic particles (<10 nm) is vital to our understanding of superparamagnetism and its applications to environmental magnetism, biogeomagnetism, iron biomineralization, and biomedical technology. However, magnetic properties of the ultrafine nanometer-sized ferrimagnetic grains are very poorly constrained because of ambiguities caused by particle magnetostatic interactions and unknown size distributions. To resolve these problems, we synthesized magnetoferritins using the recombinant human H chain ferritin (HFn). These ferrimagnetic HFn were further purified through size exclusion chromatography to obtain monodispersed ferrimagnetic HFn. Transmission electron microscopy revealed that the purified ferrimagnetic HFn are monodispersed and each consists of an iron oxide core (magnetite or maghemite) with an average core diameter of 3.9 ± 1.1 nm imbedded in an intact protein shell. The R value of the Wohlfarth-Cisowski test measured at 5 K is 0.5, indicating no magnetostatic interactions. The saturation isothermal remanent magnetization acquired at 5 K decreased rapidly with increasing temperature with a median unblocking temperature of 8.2 K. The preexponential frequency factor f0 determined by AC susceptibility is (9.2 ± 7.9) × 1010 Hz. The extrapolated Mrs/Ms and Bcr/Bc at 0 K are 0.5 and 1.12, respectively, suggesting that the ferrimagnetic HFn cores are dominated by uniaxial anisotropy. The calculated effective magnetic anisotropy energy constant Keff = 1.2 × 105 J/m3, which is larger than previously reported values for bulk magnetite and/or maghemite or magnetoferritin and is attributed to the effect of surface anisotropy. These data provide useful insights into superparamagnetism as well as biomineralization of ultrafine ferrimagnetic particles.

  10. The creation, manipulation and evolution of nanometer-scale structures in the Ag/Cu(111) system

    NASA Astrophysics Data System (ADS)

    York, Mike; Leibsle, Fred; Goedken, Aaron

    2001-03-01

    We demonstrate how we can use scanning tunneling microscopy to create nanometer-scale pits several layers deep on Ag(111) films grown on a Cu(111) substrate. The creation of these pits is accompanied by the formation of multilayer high islands. We also demonstrate the ability to manipulate small one-layer deep pits. In addition, the evolution of the islands and pits is also studied. Images show island and pit coalescence and instances of rapid and gradual decay.

  11. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

    SciTech Connect

    Grosse, Kyle L.; Pop, Eric; King, William P.

    2014-09-15

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K{sup −1}. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  12. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

    PubMed

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-03-01

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  13. TEM Study of Intergranular Fluid Distributions in Rocks at a Nanometer Scale

    NASA Astrophysics Data System (ADS)

    Hiraga, T.; Anderson, I. M.; Kohlstedt, D. L.

    2002-12-01

    The distribution of intergranular fluids in rocks plays an essential role in fluid migration and rock rheology. Structural and chemical analyses with sub-nanometer resolution is possible with transmission and scanning-transmission electron microscopy; therefore, it is possible to perform the fine-scale structural analyses required to determine the presence or absence of very thin fluid films along grain boundaries. For aqueous fluids in crustal rocks, Hiraga et al. (2001) observed a fluid morphology controlled by the relative values of the solid-solid and solid-fluid interfacial energies, which resulted in well-defined dihedral angles. Their high-resolution transmission electron microscopy (TEM) observations demonstrate that grain boundaries are tight even at a nanometer scale, consistent with the absence of aqueous fluid films. For partially molten ultra-mafic rocks, two conflicting conclusions have been reached: nanometer-thick melt films wet grain boundaries (Drury and Fitz Gerald 1996; De Kloe et al. 2000) versus essentially all grain boundaries are melt-free (Vaughan et al. 1982; Kohlstedt 1990). To resolve this conflict, Hiraga et al. (2002) examined grain boundaries in quenched partially molten peridotites. Their observations demonstrate the following: (i) Although a small fraction of the grains are separated by relatively thick (~1 μm) layers of melt, lattice fringe images obtained with a high-resolution TEM reveal that most of the remaining boundaries do not contain a thin amorphous phase. (ii) In addition, the composition of olivine-olivine grain boundaries was analyzed with a nano-beam analytical scanning TEM with a probe size of <2 nm. Although the grain boundaries contained no melt film, the concentration of Ca, Al and Ti were enhanced near the boundaries. The segregation of these elements to the grain boundaries formed enriched regions <7 nm wide. A similar pattern of chemical segregation was detected in subsolidus systems. Creep experiments on the

  14. Superresolution microscopy reveals nanometer-scale reorganization of inhibitory natural killer cell receptors upon activation of NKG2D.

    PubMed

    Pageon, Sophie V; Cordoba, Shaun-Paul; Owen, Dylan M; Rothery, Stephen M; Oszmiana, Anna; Davis, Daniel M

    2013-07-23

    Natural killer (NK) cell responses are regulated by a dynamic equilibrium between activating and inhibitory receptor signals at the immune synapse (or interface) with target cells. Although the organization of receptors at the immune synapse is important for appropriate integration of these signals, there is little understanding of this in detail, because research has been hampered by the limited resolution of light microscopy. Through the use of superresolution single-molecule fluorescence microscopy to reveal the organization of the NK cell surface at the single-protein level, we report that the inhibitory receptor KIR2DL1 is organized in nanometer-scale clusters at the surface of human resting NK cells. Nanoclusters of KIR2DL1 became smaller and denser upon engagement of the activating receptor NKG2D, establishing an unexpected crosstalk between activating receptor signals and the positioning of inhibitory receptors. These rearrangements in the nanoscale organization of surface NK cell receptors were dependent on the actin cytoskeleton. Together, these data establish that NK cell activation involves a nanometer-scale reorganization of surface receptors, which in turn affects models for signal integration and thresholds that control NK cell effector functions and NK cell development. PMID:23882121

  15. Combining Atomic Force Microscopy and Depth-Sensing Instruments for the Nanometer-Scale Mechanical Characterization of Soft Matter

    NASA Astrophysics Data System (ADS)

    Tranchida, Davide; Piccarolo, Stefano

    Complex materials exhibit a hierarchical structure where a gradient of features on nanometer scale is induced by the synthetic route eventually enhanced by the loading condition. The nanometer scale at which individual components arrange, determining their properties, is a current challenge of mechanical testing. In this work, a survey on nanoindentation is outlined based on the comparison of results obtained by Atomic Force Microscopy and Depth-Sensing Instruments and their combination. An Atomic Force Microscope equipped with a Force Transducer gives indeed the possibility to scan the sample surface in contact mode, thereby allowing one to choose a suitable position for the nanoindentation, as well as imaging the residual imprint left on the sample. The analysis of the applied load vs. penetration depth curve, also called force curve, shows the limitations of current approaches to determine elastic moduli of compliant viscoelastic materials. Significant deviations from the expected values are observed even after optimizing testing conditions, so as to minimize the artifacts like viscoelastic effects or pile-up. As rigorous approaches are yet to be applied to the interpretation of force curves accounting also of viscoelastic material behavior, an empirical calibration recently proposed by the authors is verified against a set of data on model samples spanning a range of moduli, typical of compliant materials and close to each other, so as to challenge the resolution potential of this method, as well as others in use in the literature.

  16. Bridging the Gap between the Nanometer-Scale Bottom-Up and Micrometer-Scale Top-Down Approaches for Site-Defined InP/InAs Nanowires.

    PubMed

    Zhang, Guoqiang; Rainville, Christophe; Salmon, Adrian; Takiguchi, Masato; Tateno, Kouta; Gotoh, Hideki

    2015-11-24

    This work presents a method that bridges the gap between the nanometer-scale bottom-up and micrometer-scale top-down approaches for site-defined nanostructures, which has long been a significant challenge for applications that require low-cost and high-throughput manufacturing processes. We realized the bridging by controlling the seed indium nanoparticle position through a self-assembly process. Site-defined InP nanowires were then grown from the indium-nanoparticle array in the vapor-liquid-solid mode through a "seed and grow" process. The nanometer-scale indium particles do not always occupy the same locations within the micrometer-scale open window of an InP exposed substrate due to the scale difference. We developed a technique for aligning the nanometer-scale indium particles on the same side of the micrometer-scale window by structuring the surface of a misoriented InP (111)B substrate. Finally, we demonstrated that the developed method can be used to grow a uniform InP/InAs axial-heterostructure nanowire array. The ability to form a heterostructure nanowire array with this method makes it possible to tune the emission wavelength over a wide range by employing the quantum confinement effect and thus expand the application of this technology to optoelectronic devices. Successfully pairing a controllable bottom-up growth technique with a top-down substrate preparation technique greatly improves the potential for the mass-production and widespread adoption of this technology. PMID:26348087

  17. Processing considerations for adding nanometer-scale oxides to enhance flux pinning in high-temperature superconductors

    SciTech Connect

    Xu, Y. |; Goretta, K.C.; Cuber, M.M.; Burdt, M.L.; Feng, L.R.; Chen, N.; Balachandran, U.; Xu, M.

    1997-07-01

    Several nanometer-scale oxide inclusions were added to Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} high-temperature superconductors to determine their effectiveness in creating intragranular flux-pinning sites. Powder pellets were fabricated and heat treated by partial-melt processing. Effects of the additives on melting response, superconducting properties, and microstructural development were examined. Al{sub 2}O{sub 3} additions exhibited the most promise for forming stable pinning centers, ZrO{sub 2} and SnO{sub 2} additions were moderately promising, TiO{sub 2}, Fe{sub 2}O{sub 3}, and ZnO additions were less promising, and Y{sub 2}O{sub 3} additions destroyed superconductivity.

  18. Heterogeneous nanometer-scale Joule and Peltier effects in sub-25 nm thin phase change memory devices

    NASA Astrophysics Data System (ADS)

    Grosse, Kyle L.; Pop, Eric; King, William P.

    2014-09-01

    We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ˜0.2 K temperature resolution. The heterogeneous Joule and Peltier effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.

  19. Oxide thickness mapping of ultrathin Al2O3 at nanometer scale with conducting atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Olbrich, Alexander; Ebersberger, Bernd; Boit, Christian; Vancea, Johann; Hoffmann, Horst; Altmann, Hans; Gieres, Guenther; Wecker, Joachim

    2001-05-01

    In this work, we introduce conducting atomic force microscopy (C-AFM) for the quantitative electrical characterization of ultrathin Al2O3 films on a nanometer scale length. By applying a voltage between the AFM tip and the conductive Co substrate direct tunneling currents in the sub pA range are measured simultaneously to the oxide surface topography. From the microscopic I-V characteristics the local oxide thickness can be obtained with an accuracy of 0.03 nm. A conversion scheme was developed, which allows the calculation of three-dimensional maps of the local electrical oxide thickness with sub-angstrom thickness resolution and nanometer lateral resolution from the tunneling current images. Local tunneling current variations of up to three decades are correlated with the topography and local variations of the electrical oxide thickness of only a few angstroms.

  20. Low pressure hand made PVD system for high crystalline metal thin film preparation in micro-nanometer scale

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    High crystalline metal thin film preparation in application both for catalyst substrate or electrode in any electronic devices always to be considered in material functional material research and development. As a substrate catalyst, this metal take a role as guidance for material growth in order to resulted in proper surface structure although at the end it will be removed via etching process. Meanwhile as electrodes, it will dragging charges to be collected inside. This brief discussion will elaborate general fundamental principle of physical vapor deposition (PVD) system for metal thin film preparation in micro-nanometer scale. The influence of thermodynamic parameters and metal characteristic such as melting point and particle size will be elucidated. Physical description of deposition process in the chamber can be simplified by schematic evaporation phenomena which is supported by experimental measurement such as SEM and XRD.

  1. Characterization of nanometer-scale porosity in reservoir carbonate rock by focused ion beam-scanning electron microscopy.

    PubMed

    Bera, Bijoyendra; Gunda, Naga Siva Kumar; Mitra, Sushanta K; Vick, Douglas

    2012-02-01

    Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam-scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50-300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2-5 μm) that were observed to further link with bulk pores outside the matrix. PMID:22214656

  2. Impacts of test factors on heavy ion single event multiple-cell upsets in nanometer-scale SRAM

    NASA Astrophysics Data System (ADS)

    Yinhong, Luo; Fengqi, Zhang; Hongxia, Guo; Yao, Xiao; Wen, Zhao; Lili, Ding; Yuanming, Wang

    2015-11-01

    Single event multiple-cell upsets (MCU) increase sharply with the semiconductor devices scaling. The impacts of several test factors on heavy ion single event MCU in 65 nm SRAM are studied based on the buildup of MCU test data acquiring and processing technique, including the heavy ion LET, the tilt angle, the device orientation, the test pattern and the supply voltage; the MCU physical bitmaps are extracted correspondingly. The dependencies of parameters such as the MCU percentage, MCU mean and topological pattern on these factors are summarized and analyzed. This work is meaningful for developing a more reasonable single event test method and assessing the effectiveness of anti-MCU strategies on nanometer-scale devices.

  3. Efficient mass transport by optical advection

    NASA Astrophysics Data System (ADS)

    Kajorndejnukul, Veerachart; Sukhov, Sergey; Dogariu, Aristide

    2015-10-01

    Advection is critical for efficient mass transport. For instance, bare diffusion cannot explain the spatial and temporal scales of some of the cellular processes. The regulation of intracellular functions is strongly influenced by the transport of mass at low Reynolds numbers where viscous drag dominates inertia. Mimicking the efficacy and specificity of the cellular machinery has been a long time pursuit and, due to inherent flexibility, optical manipulation is of particular interest. However, optical forces are relatively small and cannot significantly modify diffusion properties. Here we show that the effectiveness of microparticle transport can be dramatically enhanced by recycling the optical energy through an effective optical advection process. We demonstrate theoretically and experimentally that this new advection mechanism permits an efficient control of collective and directional mass transport in colloidal systems. The cooperative long-range interaction between large numbers of particles can be optically manipulated to create complex flow patterns, enabling efficient and tunable transport in microfluidic lab-on-chip platforms.

  4. Mass partitioning effects in diffusion transport.

    PubMed

    Kojic, Milos; Milosevic, Miljan; Wu, Suhong; Blanco, Elvin; Ferrari, Mauro; Ziemys, Arturas

    2015-08-28

    Frequent mass exchange takes place in a heterogeneous environment among several phases, where mass partitioning may occur at the interface of phases. Analytical and computational methods for diffusion do not usually incorporate molecule partitioning masking the true picture of mass transport. Here we present a computational finite element methodology to calculate diffusion mass transport with a partitioning phenomenon included and the analysis of the effects of partitioning. Our numerical results showed that partitioning controls equilibrated mass distribution as expected from analytical solutions. The experimental validation of mass release from drug-loaded nanoparticles showed that partitioning might even dominate in some cases with respect to diffusion itself. The analysis of diffusion kinetics in the parameter space of partitioning and diffusivity showed that partitioning is an extremely important parameter in systems, where mass diffusivity is fast and that the concentration of nanoparticles can control payload retention inside nanoparticles. The computational and experimental results suggest that partitioning and physiochemical properties of phases play an important, if not crucial, role in diffusion transport and should be included in the studies of mass transport processes. PMID:26204522

  5. Mass Transport in Global Geophysical Fluids

    NASA Technical Reports Server (NTRS)

    Chao, B. F.

    1999-01-01

    Mass transports occurring in the atmosphere-hydrosphere-solid Earth-core system (the "global geophysical fluids") are important geophysical phenomena. They occur on all temporal and spatial scales. Examples include air mass and ocean circulations, tides, hydrological water redistribution, mantle processes such as post-glacial rebound, earthquakes and tectonic motions, and core geodynamo activities. With only a few exceptions on the Earth surface, the temporal history and spatial pattern of such mass transport are often not amenable to direct observations. Space geodesy techniques, however, have the capability of monitoring certain direct consequences of the mass transport, including Earth's rotation variations, gravitational field variations, and the geocenter motion. These techniques include the very-long-baseline interferometry, satellite laser ranging and Doppler tracking, and the Global Positioning System, all entail global observational networks. While considerable advances have been made in observing and understanding of the dynamics of Earth's rotation, only the lowest-degree gravitational variations have been observed and limited knowledge of geocenter motion obtained. New space missions, projects and initiatives promise to further improve the measurements and hence our knowledge about the global mass transports. The latter contributes to our understanding and modeling capability of the geophysical processes that produce and regulate the mass transports, as well as the solid Earth's response to such changes in constraining the modeling of Earth's mechanical properties.

  6. Proximity biotinylation provides insight into the molecular composition of focal adhesions at the nanometer scale.

    PubMed

    Dong, Jing-Ming; Tay, Felicia Pei-Ling; Swa, Hannah Lee-Foon; Gunaratne, Jayantha; Leung, Thomas; Burke, Brian; Manser, Ed

    2016-01-01

    Focal adhesions are protein complexes that link metazoan cells to the extracellular matrix through the integrin family of transmembrane proteins. Integrins recruit many proteins to these complexes, referred to as the "adhesome." We used proximity-dependent biotinylation (BioID) in U2OS osteosarcoma cells to label proteins within 15 to 25 nm of paxillin, a cytoplasmic focal adhesion protein, and kindlin-2, which directly binds β integrins. Using mass spectrometry analysis of the biotinylated proteins, we identified 27 known adhesome proteins and 8 previously unknown components close to paxillin. However, only seven of these proteins interacted directly with paxillin, one of which was the adaptor protein Kank2. The proteins in proximity to β integrin included 15 of the adhesion proteins identified in the paxillin BioID data set. BioID also correctly established kindlin-2 as a cell-cell junction protein. By focusing on this smaller data set, new partners for kindlin-2 were found, namely, the endocytosis-promoting proteins liprin β1 and EFR3A, but, contrary to previous reports, not the filamin-binding protein migfilin. A model adhesome based on both data sets suggests that focal adhesions contain fewer components than previously suspected and that paxillin lies away from the plasma membrane. These data not only illustrate the power of using BioID and stable isotope-labeled mass spectrometry to define macromolecular complexes but also enable the correct identification of therapeutic targets within the adhesome. PMID:27303058

  7. Surface and grain boundary interdiffusion in nanometer-scale LSMO/BFO bilayer

    NASA Astrophysics Data System (ADS)

    Kumar, Virendra; Gaur, Anurag; Choudhary, R. J.; Gupta, Mukul

    2016-05-01

    Epitaxial 150 nm thick LSMO/BFO bilayer is deposited on STO (100) substrate by pulsed laser deposition, to study magnetoelectric effect. Unexpected low value of room temperature magnetization in bilayer indicates towards the possibility of interdiffusion. Further, sharp fall in the value of TC (53 K) also added our anxiety towards possible interdiffusion in BFO/LSMO system. Low-angle x-ray diffraction technique is used to investigate interdiffusion phenomena, and the temperature-dependent interdiffusivity is obtained by accurately monitoring the decay of the first-order modulation peak as a function of annealing time. It has been found that the diffusivity at different temperatures follows Arrhenius-type behavior. X-ray reflection (XRR) pattern obtained for the bilayer could not be fitted in the Parratt's formalism, which confirms the interdiffusion in it. Depth profiles of 209Bi, 56Fe ions measured by secondary ion mass spectroscope (SIMS) further substantiate the diffusion of these ions from upper BFO layer into lower LSMO layer.

  8. Nanometer scale elemental analysis in the helium ion microscope using time of flight spectrometry.

    PubMed

    Klingner, N; Heller, R; Hlawacek, G; von Borany, J; Notte, J; Huang, J; Facsko, S

    2016-03-01

    Time of flight backscattering spectrometry (ToF-BS) was successfully implemented in a helium ion microscope (HIM). Its integration introduces the ability to perform laterally resolved elemental analysis as well as elemental depth profiling on the nm scale. A lateral resolution of ≤54nm and a time resolution of Δt≤17ns(Δt/t≤5.4%) are achieved. By using the energy of the backscattered particles for contrast generation, we introduce a new imaging method to the HIM allowing direct elemental mapping as well as local spectrometry. In addition laterally resolved time of flight secondary ion mass spectrometry (ToF-SIMS) can be performed with the same setup. Time of flight is implemented by pulsing the primary ion beam. This is achieved in a cost effective and minimal invasive way that does not influence the high resolution capabilities of the microscope when operating in standard secondary electron (SE) imaging mode. This technique can thus be easily adapted to existing devices. The particular implementation of ToF-BS and ToF-SIMS techniques are described, results are presented and advantages, difficulties and limitations of this new techniques are discussed. PMID:26725148

  9. Texture mapping via optimal mass transport.

    PubMed

    Dominitz, Ayelet; Tannenbaum, Allen

    2010-01-01

    In this paper, we present a novel method for texture mapping of closed surfaces. Our method is based on the technique of optimal mass transport (also known as the "earth-mover's metric"). This is a classical problem that concerns determining the optimal way, in the sense of minimal transportation cost, of moving a pile of soil from one site to another. In our context, the resulting mapping is area preserving and minimizes angle distortion in the optimal mass sense. Indeed, we first begin with an angle-preserving mapping (which may greatly distort area) and then correct it using the mass transport procedure derived via a certain gradient flow. In order to obtain fast convergence to the optimal mapping, we incorporate a multiresolution scheme into our flow. We also use ideas from discrete exterior calculus in our computations. PMID:20224137

  10. Electron and proton transfer assemblies and new porous materials from nanometer-scale building blocks

    NASA Astrophysics Data System (ADS)

    Johnson, Stacy Ann

    Elegant examples of molecular engineering are found in nature that make our current small devices seem primitive. By using naturally occurring examples we can better imagine how to construct useful three dimensional nanoscaled devices. Electron and proton transfer composites were prepared using a multilayer film growth technique, in which single anionic sheets derived from inorganic solids are interleaved with cationic polyelectrolytes. This method allows for the growth of concentric monolayers of redox-active polymers on high-surface-area silica supports, and for vectorial electron transfer reactions through the layers of the "onion." Photoinduced charge separation has been observed in composites consisting of an inner polycationic layer of poly(styrene- co-N-vinylbenzyl-N'-methyl-4,4 '-bipyridine), and an outer polycationic layer of poly[Ru(bpy) 2(vbpy)]2+, vbpy = 4-vinyl-4'-methyl- 2,2'-bipyridine, bpy = 2,2' -bipyridine, which are separated by a thin inorganic sheet of Zr(HOPO 3)2·H2O. Following the logic of the proton transport mechanism found in biological membranes, a photosensitive proton pump was constructed using the same electrostatic adsorption technique. This composite was prepared with a polymeric form of a luminescent ruthenium complex, poly[Ru(bpy) 2(bpm)]2+, bpy = 2,2'-bipyridine bpm = 2,2'-bipyrimidine. The pH of a solution in which the composites were suspended changed reversibly when irradiated with visible light. A series of microporous polymer replicas were synthesized using inorganic templates. Zeolites were used as templates to prepare microporous polymer replicas with nanometer sized pore networks. Phenol-formaldehyde polymers were synthesized and cured within the channel networks of zeolites Y, beta, and L. Dissolution of the aluminosilicate framework in aqueous IHF yields an organic replica. The zeolite template exerts important topological effects on the structure and physical properties of the replica. A similar process is described

  11. Experimental studies of fundamental issues in electron transfer through nanometer scale devices

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiromichi

    Electron transfer reactions constitute many of the primary events in materials science, chemistry, physics, and biochemistry, e.g. the electron transport properties and photoexcited processes in solids and molecules, chemical reactions, corrosion, photosynthesis, respiration, and so forth. A self-assembled monolayer (SAM) film provides us with a unique environment not only to understand and manipulate the surface electronic properties of a solid, but also to control electron transfer processes at the interface. The first topic in this thesis describes the structure and electron tunneling characterization of alkanethiol SAMs on InP(100). Angle-resolved X-ray photoelectron spectroscopy was used to characterize the bonding of alkanethiols to n-InP surfaces and to measure the monolayer thickness. The results showed that the sulfur binds to In atoms on the surface, and provided film thicknesses of 6.4 A for C8H17SH, 11.1 A for C12H25SH, and 14.9 A for C16H 33SH, resulting in an average tilt angle of 55°. The analysis indicated that super-exchange coupling between the alkane chains plays an important role in defining electron tunneling barriers, especially for highly tilted chains. The second topic describes studies of cytochrome c bound to pure and mixed SAMs of o-terminated alkanethiol (terminated with pyridine, imidazole or nitrile groups) and alkanethiol on gold. Electrochemical methods are used to determine electron transfer rate constants of cytochrome c, and scanning tunneling microscopy to observe the cytochrome c on the SAM. Detailed analysis revealed direct association of the heme of cytochrome c with the terminal groups of the SAMs and a 'turning-over' of the electron transfer of cytochrome c from adiabatic to non-adiabatic regime. The third topic describes studies of oxidation and reduction of cytochrome c in solution through eleven different self-assembled monolayers (SAMs) on gold electrodes by cyclic voltammetry. Electron transfer rate constants of

  12. Nanometer-Scale Manipulation and Ultrasonic Cutting Using an Atomic Force Microscope Controlled by a Haptic Device as a Human Interface

    NASA Astrophysics Data System (ADS)

    Iwata, Futoshi; Ohara, Kouhei; Ishizu, Yuichi; Sasaki, Akira; Aoyama, Hisayuki; Ushiki, Tatsuo

    2008-07-01

    We describe a nanometer-scale manipulation and cutting method using ultrasonic oscillation scratching. The system is based on a modified atomic force microscope (AFM) coupled with a haptic device as a human interface. By handling the haptic device, the operator can directly move the AFM probe to manipulate nanometer scale objects and cut a surface while feeling the reaction from the surface in his or her fingers. As for manipulation using the system, nanometer-scale spheres were controllably moved by feeling the sensation of the AFM probe touching the spheres. As for cutting performance, the samples were prepared on an AT-cut quartz crystal resonator (QCR) set on an AFM sample holder. The QCR oscillates at its resonance frequency (9 MHz) with an amplitude of a few nanometers. Thus it is possible to cut the sample surface smoothly by the interaction between the AFM probe and the oscillating surface, even when the samples are viscoelastics such as polymers and biological samples. The ultrasonic nano-manipulation and cutting system would be a very useful and effective tool in the fields of nanometer-scale engineering and biological sciences.

  13. Oceanic mass transport by mesoscale eddies.

    PubMed

    Zhang, Zhengguang; Wang, Wei; Qiu, Bo

    2014-07-18

    Oceanic transports of heat, salt, fresh water, dissolved CO2, and other tracers regulate global climate change and the distribution of natural marine resources. The time-mean ocean circulation transports fluid as a conveyor belt, but fluid parcels can also be trapped and transported discretely by migrating mesoscale eddies. By combining available satellite altimetry and Argo profiling float data, we showed that the eddy-induced zonal mass transport can reach a total meridionally integrated value of up to 30 to 40 sverdrups (Sv) (1 Sv = 10(6) cubic meters per second), and it occurs mainly in subtropical regions, where the background flows are weak. This transport is comparable in magnitude to that of the large-scale wind- and thermohaline-driven circulation. PMID:25035491

  14. New single-molecule speckle microscopy reveals modification of the retrograde actin flow by focal adhesions at nanometer scales.

    PubMed

    Yamashiro, Sawako; Mizuno, Hiroaki; Smith, Matthew B; Ryan, Gillian L; Kiuchi, Tai; Vavylonis, Dimitrios; Watanabe, Naoki

    2014-04-01

    Speckle microscopy directly visualizes the retrograde actin flow, which is believed to promote cell-edge protrusion when linked to focal adhesions (FAs). However, it has been argued that, due to rapid actin turnover, the use of green fluorescent protein-actin, the lack of appropriate analysis algorithms, and technical difficulties, speckle microscopy does not necessarily report the flow velocities of entire actin populations. In this study, we developed a new, user-friendly single-molecule speckle (SiMS) microscopy using DyLight dye-labeled actin. Our new SiMS method enables in vivo nanometer-scale displacement analysis with a low localization error of ±8-8.5 nm, allowing accurate flow-velocity measurement for actin speckles with lifetime <5 s. In lamellipodia, both short- and long-lived F-actin molecules flow with the same speed, indicating they are part of a single actin network. These results do not support coexistence of F-actin populations with different flow speeds, which is referred to as the lamella hypothesis. Mature FAs, but not nascent adhesions, locally obstruct the retrograde flow. Interestingly, the actin flow in front of mature FAs is fast and biased toward FAs, suggesting that mature FAs attract the flow in front and actively remodel the local actin network. PMID:24501425

  15. Fast live cell imaging at nanometer scale using annihilating filter-based low-rank Hankel matrix approach

    NASA Astrophysics Data System (ADS)

    Min, Junhong; Carlini, Lina; Unser, Michael; Manley, Suliana; Ye, Jong Chul

    2015-09-01

    Localization microscopy such as STORM/PALM can achieve a nanometer scale spatial resolution by iteratively localizing fluorescence molecules. It was shown that imaging of densely activated molecules can accelerate temporal resolution which was considered as major limitation of localization microscopy. However, this higher density imaging needs to incorporate advanced localization algorithms to deal with overlapping point spread functions (PSFs). In order to address this technical challenges, previously we developed a localization algorithm called FALCON1, 2 using a quasi-continuous localization model with sparsity prior on image space. It was demonstrated in both 2D/3D live cell imaging. However, it has several disadvantages to be further improved. Here, we proposed a new localization algorithm using annihilating filter-based low rank Hankel structured matrix approach (ALOHA). According to ALOHA principle, sparsity in image domain implies the existence of rank-deficient Hankel structured matrix in Fourier space. Thanks to this fundamental duality, our new algorithm can perform data-adaptive PSF estimation and deconvolution of Fourier spectrum, followed by truly grid-free localization using spectral estimation technique. Furthermore, all these optimizations are conducted on Fourier space only. We validated the performance of the new method with numerical experiments and live cell imaging experiment. The results confirmed that it has the higher localization performances in both experiments in terms of accuracy and detection rate.

  16. Influence of nanometer scale film structure of ZDDP tribofilm on Its mechanical properties: A computational chemistry study

    NASA Astrophysics Data System (ADS)

    Onodera, Tasuku; Kuriaki, Takanori; Morita, Yusuke; Suzuki, Ai; Koyama, Michihisa; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Del Carpio, Carlos A.; Kubo, Momoji; Minfray, Clotilde; Martin, Jean-Michel; Miyamoto, Akira

    2009-11-01

    We investigated the influence of a nanometer scale film structure of a tribofilm generated from zinc dialkyldithiophosphate (ZDDP) anti-wear additive on its mechanical properties using a combined molecular dynamics (MD) and finite element (FE) method. The frictional behavior of an interface between a native iron oxide layer on steel surface and zinc metaphosphate - regarded as a model material of ZDDP tribofilm - was firstly studied using the MD method. The results showed that the iron atoms in the oxide layer diffused into the phosphate layer during the friction process. The zinc atoms in the phosphate layer also diffused into the oxide layer. Significant interdiffusion of iron and zinc atoms was observed with increasing simulation time. Thus, metallic phosphate with a gradient composition of iron and zinc atoms was formed on the phosphate/oxide interface. We then constructed an axisymmetric nanoindentation simulation model from the MD-derived structures at a certain simulation time and carried out a FE calculation. As a result, we found that the rubbed ZDDP tribofilm, including the phosphate with the gradient composition of metallic atoms, showed larger contact stiffness and hardness. The combined MD/FE simulation indicates that the tribofilm becomes stiffer and harder due to the interdiffusion of iron and zinc atoms on the tribofilm/oxide interface. We have found that the gradient composition formation in ZDDP tribofilm during friction process influences on its mechanical properties.

  17. Nanometer-scale Mechanical/Structural Properties of Molybdenum Dithiocarbamate and Zinc Dialkylsithiophosphate Tribofilms and Friction Reduction Mechanism

    NASA Astrophysics Data System (ADS)

    Ye, Jiping; Araki, Sawa; Kano, Makoto; Yasuda, Yoshiteru

    2005-07-01

    Nanometer-scale differences in mechanical and structural properties between the molybdenum- dithiocarbamate/zinc-dialkylsithiophosphate (MoDTC/ZDDP) tribofilm and ZDDP tribofilm were successfully evaluated by using atomic force microscopic phase-image techniques, Auger electron spectroscopy and X-ray photo spectroscopy. It is well known that the MoDTC/ZDDP tribofilm exhibits markedly lower friction behavior than the ZDDP tribofilm. To elucidate the mechanism of friction reduction originating from the MoDTC additive, attention was focused on property differences in the surface area in particular, from the uppermost surface to an underlying region of less than 10 nm in depth. It was found that the friction reduction due to the MoDTC/ZDDP additives originates from an inner skin layer formed by MoS2 nanostrips just below the surface. The MoS2 nanostrips were oriented in the sliding direction, had low yield strength and acted as a solid lubricant in lowering the friction coefficient of the MoDTC/ZDDP tribofilm.

  18. Efficient mass transport by optical advection

    PubMed Central

    Kajorndejnukul, Veerachart; Sukhov, Sergey; Dogariu, Aristide

    2015-01-01

    Advection is critical for efficient mass transport. For instance, bare diffusion cannot explain the spatial and temporal scales of some of the cellular processes. The regulation of intracellular functions is strongly influenced by the transport of mass at low Reynolds numbers where viscous drag dominates inertia. Mimicking the efficacy and specificity of the cellular machinery has been a long time pursuit and, due to inherent flexibility, optical manipulation is of particular interest. However, optical forces are relatively small and cannot significantly modify diffusion properties. Here we show that the effectiveness of microparticle transport can be dramatically enhanced by recycling the optical energy through an effective optical advection process. We demonstrate theoretically and experimentally that this new advection mechanism permits an efficient control of collective and directional mass transport in colloidal systems. The cooperative long-range interaction between large numbers of particles can be optically manipulated to create complex flow patterns, enabling efficient and tunable transport in microfluidic lab-on-chip platforms. PMID:26440069

  19. Delft Mass Transport model DMT-2

    NASA Astrophysics Data System (ADS)

    Ditmar, Pavel; Hashemi Farahani, Hassan; Inacio, Pedro; Klees, Roland; Zhao, Qile; Guo, Jing; Liu, Xianglin; Sun, Yu; Riva, Ricardo; Ran, Jiangjun

    2013-04-01

    Gravity Recovery And Climate Experiment (GRACE) satellite mission has enormously extended our knowledge of the Earth's system by allowing natural mass transport of various origin to be quantified. This concerns, in particular, the depletion and replenishment of continental water stocks; shrinking of polar ice sheets; deformation of the Earth's crust triggered by large earthquakes, and isostatic adjustment processes. A number of research centers compute models of temporal gravity field variations and mass transport, using GRACE data as input. One of such models - Delft Mass Transport model - is being produced at the Delft University of Technology in collaboration with the GNSS Research Center of Wuhan University. A new release of this model, DMT-2, has been produced on the basis of a new (second) release of GRACE level-1b data. This model consists of a time-series of monthly solutions spanning a time interval of more than 8 years, starting from Feb. 2003. Each solution consists of spherical harmonic coefficients up to degree 120. Both unconstrained and optimally filtered solutions are obtained. The most essential improvements of the DMT-2 model, as compared to its predecessors (DMT-1 and DMT-1b), are as follows: (i) improved estimation and elimination of low-frequency noise in GRACE data, so that strong mass transport signals are not damped; (ii) computation of accurate stochastic models of data noise for each month individually with a subsequent application of frequency-dependent data weighting, which allows statistically optimal solutions to be compiled even if data noise is colored and gradually changes in time; (iii) optimized estimation of accelerometer calibration parameters; (iv) incorporation of degree 1 coefficients estimated with independent techniques; (v) usage of state-of-the-art background models to de-alias GRACE data from rapid mass transport signals (this includes the EOT11a model of ocean tides and the latest release of the AOD1B product describing

  20. Nanometer-scale features on micrometer-scale surface texturing: a bone histological, gene expression, and nanomechanical study.

    PubMed

    Coelho, Paulo G; Takayama, Tadahiro; Yoo, Daniel; Jimbo, Ryo; Karunagaran, Sanjay; Tovar, Nick; Janal, Malvin N; Yamano, Seiichi

    2014-08-01

    Micro- and nanoscale surface modifications have been the focus of multiple studies in the pursuit of accelerating bone apposition or osseointegration at the implant surface. Here, we evaluated histological and nanomechanical properties, and gene expression, for a microblasted surface presenting nanometer-scale texture within a micrometer-scale texture (MB) (Ossean Surface, Intra-Lock International, Boca Raton, FL) versus a dual-acid etched surface presenting texture at the micrometer-scale only (AA), in a rodent femur model for 1, 2, 4, and 8weeks in vivo. Following animal sacrifice, samples were evaluated in terms of histomorphometry, biomechanical properties through nanoindentation, and gene expression by real-time quantitative reverse transcription polymerase chain reaction analysis. Although the histomorphometric, and gene expression analysis results were not significantly different between MB and AA at 4 and 8 weeks, significant differences were seen at 1 and 2 weeks. The expression of the genes encoding collagen type I (COL-1), and osteopontin (OPN) was significantly higher for MB than for AA at 1 week, indicating up-regulated osteoprogenitor and osteoblast differentiation. At 2 weeks, significantly up-regulated expression of the genes for COL-1, runt-related transcription factor 2 (RUNX-2), osterix, and osteocalcin (OCN) indicated progressive mineralization in newly formed bone. The nanomechanical properties tested by the nanoindentation presented significantly higher-rank hardness and elastic modulus for the MB compared to AA at all time points tested. In conclusion, the nanotopographical featured surfaces presented an overall higher host-to-implant response compared to the microtextured only surfaces. The statistical differences observed in some of the osteogenic gene expression between the two groups may shed some insight into the role of surface texture and its extent in the observed bone healing mechanisms. PMID:24813260

  1. Three-dimensional nanometer scale analyses of precipitate structures and local compositions in titanium aluminide engineering alloys

    NASA Astrophysics Data System (ADS)

    Gerstl, Stephan S. A.

    Titanium aluminide (TiAl) alloys are among the fastest developing class of materials for use in high temperature structural applications. Their low density and high strength make them excellent candidates for both engine and airframe applications. Creep properties of TiAl alloys, however, have been a limiting factor in applying the material to a larger commercial market. In this research, nanometer scale compositional and structural analyses of several TiAl alloys, ranging from model Ti-Al-C ternary alloys to putative commercial alloys with 10 components are investigated utilizing three dimensional atom probe (3DAP) and transmission electron microscopies. Nanometer sized borides, silicides, and carbide precipitates are involved in strengthening TiAl alloys, however, chemical partitioning measurements reveal oxygen concentrations up to 14 at. % within the precipitate phases, resulting in the realization of oxycarbide formation contributing to the precipitation strengthening of TiAl alloys. The local compositions of lamellar microstructures and a variety of precipitates in the TiAl system, including boride, silicide, binary carbides, and intermetallic carbides are investigated. Chemical partitioning of the microalloying elements between the alpha2/gamma lamellar phases, and the precipitate/gamma-matrix phases are determined. Both W and Hf have been shown to exhibit a near interfacial excess of 0.26 and 0.35 atoms nm-2 respectively within ca. 7 nm of lamellar interfaces in a complex TiAl alloy. In the case of needle-shaped perovskite Ti3AlC carbide precipitates, periodic domain boundaries are observed 5.3+/-0.8 nm apart along their growth axis parallel to the TiAl[001] crystallographic direction with concomitant composition variations after 24 hrs. at 800°C.

  2. MEMS Actuators for Tuning Nanometer-scale Airgaps in Heterostructures and Optical Instrumentation for Glacier Ice Studies

    NASA Astrophysics Data System (ADS)

    Chan, Wing Shan

    MEMS Actuators for Tuning Nanometer-scale Airgaps in Heterostructures: We developed a new actuator microstructure to control the spacing between closely spaced surfaces. Creating and controlling nanometer gaps is of interest in areas such as plasmonics and quantum electronics. For example, energy states in quantum well heterostructures can be tuned by adjusting the physical coupling distance between wells. Unfortunately, such an application calls for active control of a nano-scale air gap between surfaces which are orders of magnitude larger, which is difficult due to stiction forces. A vertical electrostatic wedge actuator was designed to control the air gap between two closely spaced quantum wells in a collapsed cantilever structure. A six-mask fab- rication process was developed and carried out on an InGaAs/InP quantum well het- erostructure on an InP substrate. Upon actuation, the gap spacing between the surfaces was tuned over a maximum range of 55 nm from contact with an applied voltage of 60 V. Challenges in designing and fabricating the device are discussed. Optical Instrumentation for Glacier Ice Studies: We explored new optical instrumentation for glacier ice studies. Glacier ice, such as that of the Greenland and Antarctic ice sheets, is formed by the accumulation of snowfall over hundreds of thousands of years. Not all snowfalls are the same. Their isotopic compositions vary according to the planet's climate at the time, and may contain part of the past atmosphere. The physical properties and chemical content of the ice are therefore proxies of Earth's climate history. In this work, new optical methods and instrumentation based on light scattering and polarization were developed to more efficiently study glacier ice. Field deployments in Antarctica of said instrumentation and results acquired are presented.

  3. Friction characteristics of Cd-rich carbonate films on calcite surfaces: implications for compositional differentiation at the nanometer scale

    PubMed Central

    2009-01-01

    Lateral Force Microscopy (LFM) studies were carried out on cleaved calcite sections in contact with solutions supersaturated with respect to otavite (CdCO3) or calcite-otavite solid solutions (SS) as a means to examine the potential for future application of LFM as a nanometer-scale mineral surface composition mapping technique. Layer-by-layer growth of surface films took place either by step advancement or by a surface nucleation and step advancement mechanisms. Friction vs. applied load data acquired on the films and the calcite substrate were successfully fitted to the Johnson Kendall Roberts (JKR) model for single asperity contacts. Following this model, friction differences between film and substrate at low loads were dictated by differences in adhesion, whereas at higher load they reflect differences in contact shear strength. In most experiments at fixed load, the film showed higher friction than the calcite surface, but the friction-load dependence for the different surfaces revealed that at low loads (0–40 nN), a calcian otavite film has lower friction than calcite; a result that is contrary to earlier LFM reports of the same system. Multilayer films of calcian-otavite displayed increasing friction with film thickness, consistent with the expectation that the film surface composition will become increasingly Cd-rich with increasing thickness. Both load- and thickness-dependence trends support the hypothesis that the contact shear strength correlates with the hydration enthalpy of the surface ions, thereby imparting friction sensitivity in the LFM to mineral-water interface composition. PMID:19549312

  4. Photoinduced mass transport in azo compounds

    NASA Astrophysics Data System (ADS)

    Klismeta, K.; Teteris, J.; Aleksejeva, J.

    2013-12-01

    The photoinduced changes of optical properties in azobenzene containing compound thin films were studied under influence of polarized and non-polarized 532 nm laser light. Under influence of light azo compounds experience trans-cis isomerisation process, that can be observed in the absorbance spectrum of the sample. If the light is linearly polarized, molecules align perpendicularly to the electric field vector and as a result photoinduced dichroism and birefringence is obtained. If a known lateral polarization modulation of the light beam is present, mass transport of the azobenzene containing compound occurs. By measuring the surface relief with a profilometer the direction of mass transport can be determined. The studies of this work show that direct holographic recording of surface relief gratings can be used in optoelectronics, telecommunications and data storage.

  5. Resolving three-dimensional shape of sub-50 nm wide lines with nanometer-scale sensitivity using conventional optical microscopes

    SciTech Connect

    Attota, Ravikiran Dixson, Ronald G.

    2014-07-28

    We experimentally demonstrate that the three-dimensional (3-D) shape variations of nanometer-scale objects can be resolved and measured with sub-nanometer scale sensitivity using conventional optical microscopes by analyzing 4-D optical data using the through-focus scanning optical microscopy (TSOM) method. These initial results show that TSOM-determined cross-sectional (3-D) shape differences of 30 nm–40 nm wide lines agree well with critical-dimension atomic force microscope measurements. The TSOM method showed a linewidth uncertainty of 1.22 nm (k = 2). Complex optical simulations are not needed for analysis using the TSOM method, making the process simple, economical, fast, and ideally suited for high volume nanomanufacturing process monitoring.

  6. Nanometer-scale chemical heterogeneities of black carbon materials and their impacts on PCB sorption properties: soft X-ray spectromicroscopy study

    SciTech Connect

    Tae Hyun Yoon; Karim Benzerara; Sungwoo Ahn; Richard G. Luthy; Tolek Tyliszczak; Gordon E. Brown, Jr.

    2006-10-01

    Synchrotron-based soft X-ray spectromicroscopy was used to probe nanometer-scale chemical heterogeneities of black carbon (BC) materials, including anthracite coal, coke, and activated carbon (AC), and to study their impact on the partitioning of one type of polychlorinated biphenyls (PCB-166: 2,3,4,4',5,6 hexachloro biphenyl) onto AC particles. Various carbon species (e.g., aromatic, ketonic/phenolic, and carboxylic functional groups) were found in all of the BC materials examined, and impurities (e.g., carbonate and potassium ions in anthracite coal) were identified in nanometer-scale regions of these samples. The show that these chemical heterogeneities in AC particles influence their sorption of hydrophobic organic compounds (HOCs). PCB-166 was found to accumulate preferentially on AC particles with the highest content of aromatic functionalities. These new findings from X-ray spectromicroscopy have the following implications for the role of BC materials in the environment: (1) the functional groups of BC materials vary on a 25-nanometer scale, and so does the abundance of the HOCs; (2) molecular-level characterization of HOC sorption preferences on AC will lead to an improved understanding of AC sorption properties for the remediation of HOCs in soils and sediments. 40 refs., 3 figs.

  7. Nanometer-Scale Epitaxial Strain Release in Perovskite Heterostructures Using 'SrAlOx' Sliding Buffer Layers

    SciTech Connect

    Bell, Christopher

    2011-08-11

    relative crystalline orientation between the filmand the substrate. For 4 uc or greater, the perovskite epitaxial template is lost and the LAO filmis amorphous. These results suggest that metastable interlayers can be used for strain release on the nanometer scale.

  8. Energy and mass transport in the thermosphere

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.; Spencer, N. W.

    1979-01-01

    Examples illustrating the effects of large scale energy and mass transport in the thermosphere discussed include: (1) The seasonal variations reveal temperature, composition, and ionospheric anomalies involving energy exchange between the thermosphere and mesosphere. (2) The midnight temperature maximum in the thermosphere is interpreted as a signature of tidal waves emanating from the mesosphere and momentum coupling associated with ion drag. (3) The ionospheric storm in the F region illustrates the intricate effects of large scale atmospheric winds driven by magnetospheric energization processes. (4) Atmospheric signatures of Joule heating and electric field momentum coupling are markedly different.

  9. In-situ, nanometer-scale visualization of nanoparticle phase transitions and light-matter interactions in 2- and 3-D

    NASA Astrophysics Data System (ADS)

    Dionne, Jennifer

    2015-03-01

    We present new spectroscopic techniques that enable visualization of nanoparticle phase transitions in reactive environments and light-matter interactions with nanometer-scale resolution. First, we directly monitor hydrogen absorption and desorption in individual palladium nanocrystals. Our approach is based on in-situ electron energy-loss spectroscopy (EELS) in an environmental transmission electron microscope. By probing hydrogen-induced shifts of the palladium plasmon resonance, we find that hydrogen loading and unloading isotherms are characterized by abrupt phase transitions and macroscopic hysteresis gaps. These results suggest that alpha and beta phases do not coexist in single-crystalline nanoparticles, in striking contrast with conventional phase transitions and ensemble measurements of Pd nanoparticles. Then, we then extend these techniques to monitor nanoparticle reactions in a liquid environment. By constructing a flow chamber, we directly monitor growth and assembly of colloidal plasmonic metamaterial constituents induced by chemical catalysts. Lastly, we introduce a novel tomographic technique, cathodoluminescence spectroscopic tomography, to probe optical properties in three dimensions with nanometer-scale spatial and spectral resolution. Particular attention is given to reconstructing a 3D metamaterial resonator supporting broadband electric and magnetic resonances at optical frequencies. Our tomograms allow us to locate regions of efficient cathodoluminescence across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. The experimental signal can further be correlated with the radiative local density of optical states in particular regions of the reconstruction. Our results provide a general framework for visualizing chemical reactions and light-matter interactions in plasmonic materials and metamaterials, with sub-nanometer-scale resolution, and in three-dimensions.

  10. The collimation of intense relativistic electron beams generated by ultra-intense femtosecond laser in nanometer-scale solid fiber array

    SciTech Connect

    Liao, Leng; Wu, Weidong; Wang, Chaoyang; Zhou, Minjie; Fu, Zhibing; Tang, Yongjian

    2014-02-24

    A scheme to collimate the ultra-intense laser generated MeV electrons by nanometer-scale solid fiber array is proposed. Unlike previous resistivity-structured target schemes, not the magnetic field but the electric field due to the anisotropic resistivity acts to collimate the divergent fast electrons. This concept is well supported by analytical estimation and numerical calculation. The measurements of collimated MeV electron beams at rear of carbon nanotube arrays irradiated by intense femtosecond laser show the viability of this scheme. These results indicate that potential applications include radiography, fast electron beam focusing, and perhaps the electron collimation for fast ignition of inertial confined fusion.

  11. The collimation of intense relativistic electron beams generated by ultra-intense femtosecond laser in nanometer-scale solid fiber array

    NASA Astrophysics Data System (ADS)

    Liao, Leng; Wu, Weidong; Wang, Chaoyang; Zhou, Minjie; Fu, Zhibing; Tang, Yongjian

    2014-02-01

    A scheme to collimate the ultra-intense laser generated MeV electrons by nanometer-scale solid fiber array is proposed. Unlike previous resistivity-structured target schemes, not the magnetic field but the electric field due to the anisotropic resistivity acts to collimate the divergent fast electrons. This concept is well supported by analytical estimation and numerical calculation. The measurements of collimated MeV electron beams at rear of carbon nanotube arrays irradiated by intense femtosecond laser show the viability of this scheme. These results indicate that potential applications include radiography, fast electron beam focusing, and perhaps the electron collimation for fast ignition of inertial confined fusion.

  12. Lower nanometer-scale size limit for the deformation of a metallic glass by shear transformations revealed by quantitative AFM indentation

    PubMed Central

    Bennewitz, Roland

    2015-01-01

    Summary We combine non-contact atomic force microscopy (AFM) imaging and AFM indentation in ultra-high vacuum to quantitatively and reproducibly determine the hardness and deformation mechanisms of Pt(111) and a Pt57.5Cu14.7Ni5.3P22.5 metallic glass with unprecedented spatial resolution. Our results on plastic deformation mechanisms of crystalline Pt(111) are consistent with the discrete mechanisms established for larger scales: Plasticity is mediated by dislocation gliding and no rate dependence is observed. For the metallic glass we have discovered that plastic deformation at the nanometer scale is not discrete but continuous and localized around the indenter, and does not exhibit rate dependence. This contrasts with the observation of serrated, rate-dependent flow of metallic glasses at larger scales. Our results reveal a lower size limit for metallic glasses below which shear transformation mechanisms are not activated by indentation. In the case of metallic glass, we conclude that the energy stored in the stressed volume during nanometer-scale indentation is insufficient to account for the interfacial energy of a shear band in the glassy matrix. PMID:26425424

  13. Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a fiber tip of scanning near-field optical microscopy

    SciTech Connect

    Atie, Elie M.; Xie, Zhihua; El Eter, Ali; Salut, Roland; Baida, Fadi I.; Grosjean, Thierry; Nedeljkovic, Dusan; Tannous, Tony

    2015-04-13

    Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nanometer scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e., in contact to the nanostructures. In this paper, we demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of “remote” (non contact) sensing on the nanometer scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM (Scanning Near-field Optical Microscopy) fiber tip, we introduce an ultra-compact, moveable, and background-free optical nanosensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nanometer accuracy. This work paves the way towards an alternative class of nanopositioning techniques, based on the monitoring of diffraction-free plasmon resonance, that are alternative to nanomechanical and diffraction-limited optical interference-based devices.

  14. GROUNDWATER MASS TRANSPORT AND EQUILIBRIUM CHEMISTRY MODEL FOR MULTICOMPONENT SYSTEMS

    EPA Science Inventory

    A mass transport model, TRANQL, for a multicomponent solution system has been developed. The equilibrium interaction chemistry is posed independently of the mass transport equations which leads to a set of algebraic equations for the chemistry coupled to a set of differential equ...

  15. Direct observation of nanometer-scale strain field around CoSi{sub 2}/Si interface using scanning moiré fringe imaging

    SciTech Connect

    Kim, Suhyun; Jung, Younheum; Jung Kim, Joong; Byun, Gwangseon; Lee, Sunyoung; Lee, Heabum

    2014-04-21

    We report the use of scanning moiré fringe (SMF) imaging through high-angle annular dark-field scanning transmission electron microscopy (STEM) to measure the strain field around a CoSi{sub 2} contact embedded in the source and drain (S/D) region of a transistor. The atomic arrangement of the CoSi{sub 2}/Si (111) interface was determined from the high-resolution (HR)-STEM images, and the strain field formed around the S/D region was revealed by nanometer-scale SMFs appearing in the STEM image. In addition, we showed that the strain field in the S/D region measured by SMF imaging agreed with results obtained via peak-pairs analysis of HR-STEM images.

  16. Electric current induced forward and anomalous backward mass transport

    NASA Astrophysics Data System (ADS)

    Somaiah, Nalla; Sharma, Deepak; Kumar, Praveen

    2016-05-01

    Multilayered test samples were fabricated in form of standard Blech structure, where W was used as the interlayer between SiO2 substrate and Cu film. Electromigration test was performed at 250 °C by passing an electric current with a nominal density of 3.9  ×  1010 A m‑2. In addition to the regular electromigration induced mass transport ensuing from the cathode towards the anode, we also observed anomalous mass transport from the anode to the cathode, depleting Cu from the anode as well. We propose an electromigration-thermomigration coupling based reasoning to explain the observed mass transport.

  17. Mass transport by mode-2 internal solitary-like waves

    NASA Astrophysics Data System (ADS)

    Deepwell, David; Stastna, Marek

    2016-05-01

    We present the first three-dimensional numerical simulations of the mass transport capabilities of mode-2 waves formed by a lock-release mechanism with both single and double pycnocline stratifications. Single pycnoclines and double pycnoclines with a small spacing between the pycnocline centres were found to exhibit large Lee instabilities which formed during the collapse of the intermediate density region. These instabilities led to the generation of vorticity dipoles across the mid-depth, and thereby contributed to the reduction in the mass transported by the wave. A double pycnocline with a separation of approximately 12% of the depth between the two pycnocline centres was found to transport a passive tracer optimally for the longest time-period. Increasing Schmidt number correlated with increasing mass transport, while decreasing the tracer diffusivity led to increasing mass transport, but only when a trapped core existed. Contrasted two-dimensional simulations reveal that in certain cases, most noticeably the optimal transport case, the mass transport is significantly different from the corresponding three-dimensional simulation.

  18. Dynamics of a surface-modified miniaturized SiN mechanical resonator via a nanometer-scale pore array.

    PubMed

    Lee, Eun Joong; Cho, Myung Rae; Kim, Seunghwan; Park, Yun Daniel; Kouh, Taejoon

    2016-05-13

    We have fabricated porous miniaturized SiN resonators with various dimensions and studied their mechanical dynamics at their resonant modes. The surface modification of the resonators has been achieved by etching through a thin porous anodic aluminum oxide (AAO) mask, prepared by two-step anodization. Even though these porous resonators show well-defined Lorentzian line-shapes at their resonant modes, the corresponding fundamental flexural resonance frequencies are lower than those from typical non-porous resonators. The change in the resonance frequency is due to the presence of the pores on the surface, which reduces the effective tensile stress across the beam structure, as shown from both experimental measurements and the computational model. In addition, the observed quality factor reveals the level of dissipation originating from the surface modification. The principal dissipation mechanism is found to be gas damping in the free molecular flow regime. Based on the dissipation measurement, one can see an increase in the surface-to-mass ratio, which is responsible for the increased dissipation in the porous beam structure. The work presented here demonstrates simple integration of mechanical elements with a nanopatterning technique based on an AAO as well as the tuning of mechanics via surface modification at a small scale. Such a scheme could provide an additional degree of freedom in developing a mechanical sensing element with enhanced effective surface area. PMID:27039942

  19. Dynamics of a surface-modified miniaturized SiN mechanical resonator via a nanometer-scale pore array

    NASA Astrophysics Data System (ADS)

    Lee, Eun Joong; Cho, Myung Rae; Kim, Seunghwan; Park, Yun Daniel; Kouh, Taejoon

    2016-05-01

    We have fabricated porous miniaturized SiN resonators with various dimensions and studied their mechanical dynamics at their resonant modes. The surface modification of the resonators has been achieved by etching through a thin porous anodic aluminum oxide (AAO) mask, prepared by two-step anodization. Even though these porous resonators show well-defined Lorentzian line-shapes at their resonant modes, the corresponding fundamental flexural resonance frequencies are lower than those from typical non-porous resonators. The change in the resonance frequency is due to the presence of the pores on the surface, which reduces the effective tensile stress across the beam structure, as shown from both experimental measurements and the computational model. In addition, the observed quality factor reveals the level of dissipation originating from the surface modification. The principal dissipation mechanism is found to be gas damping in the free molecular flow regime. Based on the dissipation measurement, one can see an increase in the surface-to-mass ratio, which is responsible for the increased dissipation in the porous beam structure. The work presented here demonstrates simple integration of mechanical elements with a nanopatterning technique based on an AAO as well as the tuning of mechanics via surface modification at a small scale. Such a scheme could provide an additional degree of freedom in developing a mechanical sensing element with enhanced effective surface area.

  20. MODELLING SEDIMENT TRANSPORT FOR THE LAKE MICHIGAN MASS BALANCE PROJECT

    EPA Science Inventory

    A sediment transport model is one component of the overall ensemble of models being developed for the Lake Michigan Mass Balance. The SEDZL model is being applied to simulate the fine-grained sediment transport in Lake Michigan for the 1982-1983 and 1994-1995 periods. Model perf...

  1. Mass Transportation Operators' Beliefs about Visual Impairment.

    ERIC Educational Resources Information Center

    Almon, Pamela A.

    2001-01-01

    A study investigated 171 mass transit operators' beliefs about blindness and the factors that may influence their beliefs. There were statistically significant differences among transit operators' beliefs on the basis of the operators' ethnicity. White participants had significantly fewer irrational beliefs about blindness than Hispanic and…

  2. Cell-free synthesis of a functional G protein-coupled receptor complexed with nanometer scale bilayer discs

    PubMed Central

    2011-01-01

    Background G protein coupled receptors (GPCRs) represent the largest family of membrane proteins in the human genome and the richest source of targets for the pharmaceutical industry. A major limitation to characterizing GPCRs has been the difficulty in developing high-level heterologous expression systems that are cost effective. Reasons for these difficulties include inefficient transport and insertion in the plasma membrane and cytotoxicity. Additionally, GPCR purification requires detergents, which have a negative effect on receptor yields and stability. Results Here we report a detergent-free cell-free protein expression-based method to obtain pharmacologically active GPCRs in about 2 hours. Our strategy relies on the co-translational insertion of modified GPCRs into nanometer-sized planar membranes. As a model we employed an engineered β2-adrenergic receptor in which the third intracellular loop has been replaced with T4 lysozyme (β2AR -T4L). We demonstrated that nanolipoprotein particles (NLPs) are necessary for expression of active β2AR -T4L in cell-free systems. The binding specificity of the NLP- β2AR-T4L complex has been determined by competitive assays. Our results demonstrate that β2AR-T4L synthesized in vitro depends on similar oxidative conditions as those required by an in vivo-expressed receptor. Conclusions Although the activation of β2AR-T4L requires the insertion of the T4 lysozyme sequence and the yield of that active protein limited, our results conceptually prove that cell-free protein expression could be used as a fast approach to express these valuable and notoriously difficult-to-express proteins. PMID:21605442

  3. Mass Distribution and Mass Transport in the Earth System: Recent Scientific Progress Due to Interdisciplinary Research

    NASA Astrophysics Data System (ADS)

    Kusche, Jürgen; Klemann, Volker; Sneeuw, Nico

    2014-11-01

    This Special Issue on "Mass Distribution and Mass Transport in the Earth System: Recent Scientific Progress due to Interdisciplinary Research" reports a number of findings resulting from a collaborative effort run from 2006 until 2013, in the framework of the DFG Priority Program 1257 "Mass Distribution and Mass Transport in the Earth System". Contributions have been arranged along five lines, i.e. (1) improvements in geodesy: satellite mass monitoring through gravimetry and altimetry, (2) applications in large-scale hydrology, (3) applications in solid Earth research, (4) applications in cryospheric research, (5) applications in ocean sciences.

  4. Mass-Transport Properties In Growth Of Crystals From Vapors

    NASA Technical Reports Server (NTRS)

    Wiedemeier, H.

    1992-01-01

    Brief report summarizes results of experimental and theoretical studies of mass-transport properties of GeSe/Gel4 and Hg0.8Cd0.2Te systems in connection with growth of crystals in closed ampoules. Primary emphasis in studies was on thermochemical analyses, on development of mathematical models to predict diffusion-limited mass transport, and on comparison of theoretically predicted with experimental fluxes. Results applied to design, preparation, performance, and analysis of crystal-growth experiments of semiconducting materials on Earth and in outer space. Model extended to predict mass flux and overall composition of transport products of Hg0.8Cd0.2Te transport system.

  5. Space Geodesy Monitoring Mass Transport in Global Geophysical Fluids

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    2004-01-01

    Mass transports occurring in the atmosphere-hydrosphere-cryosphere-solid Earth-core system (the 'global geophysical fluids') are important geophysical phenomena. They occur on all temporal and spatial scales. Examples include air mass and ocean circulations, oceanic and solid tides, hydrological water and idsnow redistribution, mantle processes such as post-glacial rebound, earthquakes and tectonic motions, and core geodynamo activities. The temporal history and spatial pattern of such mass transport are often not amenable to direct observations. Space geodesy techniques, however, have proven to be an effective tool in monitorihg certain direct consequences of the mass transport, including Earth's rotation variations, gravitational field variations, and the geocenter motion. Considerable advances have been made in recent years in observing and understanding of these geodynamic effects. This paper will use several prominent examples to illustrate the triumphs in research over the past years under a 'Moore's law' in space geodesy. New space missions and projects promise to further advance our knowledge about the global mass transports. The latter contributes to our understanding of the geophysical processes that produce and regulate the mass transports, as well as of the solid Earth's response to such changes in terms of Earth's mechanical properties.

  6. Lithium mass transport in ceramic breeder materials

    SciTech Connect

    Blackburn, P.E.; Johnson, C.E.

    1990-01-01

    The objective of this activity is to measure the lithium vaporization from lithium oxide breeder material under differing temperature and moisture partial pressure conditions. Lithium ceramics are being investigated for use as tritium breeding materials. The lithium is readily converted to tritium after reacting with a neutron. With the addition of 1000 ppM H{sub 2} to the He purge gas, the bred tritium is readily recovered from the blanket as HT and HTO above 400{degree}C. Within the solid, tritium may also be found as LiOT which may transport lithium to cooler parts of the blanket. The pressure of LiOT(g), HTO(g), or T{sub 2}O(g) above Li{sub 2}O(s) is the same as that for reactions involving hydrogen. In our experiments we were limited to the use of hydrogen. The purpose of this work is to investigate the transport of LiOH(g) from the blanket material. 8 refs., 1 fig., 3 tabs.

  7. An easy-to-use single-molecule speckle microscopy enabling nanometer-scale flow and wide-range lifetime measurement of cellular actin filaments.

    PubMed

    Yamashiro, Sawako; Mizuno, Hiroaki; Watanabe, Naoki

    2015-01-01

    Single-molecule speckle (SiMS) microscopy has been a powerful method to analyze actin dynamics in live cells by tracking single molecule of fluorescently labeled actin. Recently we developed a new SiMS method, which is easy-to-use for inexperienced researchers and achieves high spatiotemporal resolution. In this method, actin labeled with fluorescent DyLight dye on lysines is employed as a probe. Electroporation-mediated delivery of DyLight-actin (DL-actin) into cells enables to label cells with 100% efficiency at the optimal density. DL-actin labels cellular actin filaments including formin-based structures with improved photostability and brightness compared to green fluorescent protein-actin. These favorable properties of DL-actin extend time window of the SiMS analysis. Furthermore, the new SiMS method enables nanometer-scale displacement analysis with a low localization error of ±8-8.5 nm. With these advantages, our new SiMS microscopy method will help researchers to investigate various actin remodeling processes. In this chapter, we introduce the methods for preparation of DL-actin probes, electroporation to deliver DL-actin, the SiMS imaging and data analysis. PMID:25640423

  8. Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

    NASA Astrophysics Data System (ADS)

    Hollander, R. W.; Bom, V. R.; van Eijk, C. W. E.; Faber, J. S.; Hoevers, H.; Kruit, P.

    1994-09-01

    The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 10 5 Events per second, 90% of which are accidental. In the histograms the "true" to "accidental" ratio will be 5. The dead time is 15%.

  9. Mass transport limitation in implantable defibrillator batteries

    NASA Astrophysics Data System (ADS)

    Schmidt, C.; Tam, G.; Scott, E.; Norton, J.; Chen, K.

    Using cells with lithium reference electrodes, the power-limiting behavior in the lithium-SVO cell was shown to be due to a rapid voltage transition at the anode. A novel test cell was developed to explore the influence of current density, bulk LiAsF 6 concentration, separator type and separator proximity to the anode on the time to onset ( τ) of the anode polarization. The results were found to follow a relationship, iτ1/2∝ Cbulk, consistent with the Sand equation. This relationship also predicts that the critical concentration of LiAsF 6, at which onset of the anode polarization occurs, is near the solubility limit of LiAsF 6 in our system (around 3.5-4.0 M). This general phenomenon was found to be quantitatively similar for two dissimilar separator types, and the anode polarization could also be induced in the absence of separator at high concentration and current density. However, it appears that τ decreases with closer proximity of the separator to the anode surface (i.e. cell stack pressure), suggesting that the effect of separator is to inhibit convective transport to and from the Li surface.

  10. Frontiers in Cancer Nanomedicine: Directing Mass Transport through Biological Barriers

    PubMed Central

    Ferrari, Mauro

    2010-01-01

    The physics of mass transport within body compartments and across biological barriers differentiates cancers from healthy tissues. Variants of nanoparticles can be manufactured in combinatorially large sets, varying only one transport-affecting design parameter at a time. Nanoparticles can also be used as building blocks for systems that perform sequences of coordinated actions, in accordance to a prescribed logic. These are referred to as Logic-Embedded Vectors “(LEV)” in the following. Nanoparticles and LEVs are ideal probes for the determination of mass transport laws in tumors, acting as imaging contrast enhancers, and can be employed for the lesion-selective delivery of therapy. Their size, shape, density and surface chemistry dominate convective transport in the blood stream, margination, cell adhesion, selective cellular uptake, as well as sub-cellular trafficking and localization. As argued here, the understanding of transport differentials in cancer, termed ‘transport oncophysics’ unveils a new promising frontier in oncology: the development of lesion-specific delivery particulates that exploit mass transport differentials to deploy treatment of greater efficacy and reduced side effects. PMID:20079548

  11. Diffusion mass transport in liquid phase epitaxial growth of semiconductors

    SciTech Connect

    Dost, S.; Qin, Z.; Kimura, M.

    1996-12-01

    A numerical simulation model for the mass transport occurring during the liquid phase epitaxial growth of AlGaAs is presented. The mass transport equations in the liquid and solid phases, and the relationships between concentrations and temperature obtained from the phase diagram constitute the governing equations. These equations together with appropriate interface and boundary conditions were solved numerically by the Finite Element Method. Numerical results show the importance of diffusion into the solid phase, affecting the composition of grown layers. Simulation results agree with experiments.

  12. Mass and Momentum Turbulent Transport Experiments with Confined Coaxial Jets

    NASA Technical Reports Server (NTRS)

    Johnson, B. V.; Bennett, J. C.

    1981-01-01

    Downstream mixing of coaxial jets discharging in an expanded duct was studied to obtain data for the evaluation and improvement of turbulent transport models currently used in a variety of computational procedures throughout the propulsion community for combustor flow modeling. Flow visualization studies showed four major shear regions occurring; a wake region immediately downstream of the inlet jet inlet duct; a shear region further downstream between the inner and annular jets; a recirculation zone; and a reattachment zone. A combination of turbulent momentum transport rate and two velocity component data were obtained from simultaneous measurements with a two color laser velocimeter (LV) system. Axial, radial and azimuthal velocities and turbulent momentum transport rate measurements in the r-z and r-theta planes were used to determine the mean value, second central moment (or rms fluctuation from mean), skewness and kurtosis for each data set probability density function (p.d.f.). A combination of turbulent mass transport rate, concentration and velocity data were obtained system. Velocity and mass transport in all three directions as well as concentration distributions were used to obtain the mean, second central moments, skewness and kurtosis for each p.d.f. These LV/LIF measurements also exposed the existence of a large region of countergradient turbulent axial mass transport in the region where the annular jet fluid was accelerating the inner jet fluid.

  13. A multi-resolution approach for optimal mass transport

    NASA Astrophysics Data System (ADS)

    Dominitz, Ayelet; Angenent, Sigurd; Tannenbaum, Allen

    2007-09-01

    Optimal mass transport is an important technique with numerous applications in econometrics, fluid dynamics, automatic control, statistical physics, shape optimization, expert systems, and meteorology. Motivated by certain problems in image registration and medical image visualization, in this note, we describe a simple gradient descent methodology for computing the optimal L2 transport mapping which may be easily implemented using a multiresolution scheme. We also indicate how the optimal transport map may be computed on the sphere. A numerical example is presented illustrating our ideas.

  14. Degree-1 Surface Mass Transport and Geocenter Motion

    NASA Astrophysics Data System (ADS)

    Wu, X.

    2015-12-01

    The longest-wavelength and hemisphere asymmetric surface mass transport is characterized by three degree-one spherical harmonic components. Such mass transport modes cause geocenter motion between the center-of-mass of the total Earth system (CM) and the center-of-figure of the solid Earth surface (CF), and deforms the solid Earth. GRACE's K-band ranging data system is not sensitive to these three variation modes. For a complete spherical harmonic spectral coverage of mass transport, degree-1 surface mass changes estimated through geocenter motion or degree-1 mass/deformation signatures from other space geodetic techniques should be combined with GRACE's time-variable gravity data. The degree-1 coefficients are critically important for mass variation assessments over large regions. For example, 1 mm error in geocenter motion can result in an error of 190 gigatons of global oceanic water mass change or, equivalently, an error of 0.5 mm of global mean sea level change when the geocenter motion is converted to degree-1 mass and combined with GRACE data. Yet, several different methods of geocenter motion estimation differ in results by more than 1 mm in annual amplitude. These differences have to be resolved after 13 years of successful GRACE operation. Recently, the difference between results from direct satellite laser ranging (SLR) determination and from a global inversion of Global Navigation Satellite System (GNSS) deformation measurements, GRACE, and an ocean bottom pressure (OBP) model has been largely reconciled as due to SLR's sparse station distribution. This result and our current efforts to examine possible systematic errors in GNSS data and the OBP model will be discussed along with a future perspective.

  15. Mass transfer and transport in a geologic environment

    SciTech Connect

    Chambre, P.L.; Pigford, T.H.; Lee, W.W.L.; Ahn, J.; Kajiwara, S.; Kim, C.L.; Kimura, H.; Lung, H.; Williams, W.J.; Zavoshy, S.J.

    1985-04-01

    This report is in a continuing series of reports that present analytic solutions for the dissolution and hydrogeologic transport of radionuclides from geologic repositories of nuclear waste. Previous reports have dealt mainly with radionuclide transport in the far-field, away from the effects of the repository. In the present report, the emphasis is on near-field processes, the transfer and transport of radionuclides in the vicinity of the waste packages. The primary tool used in these analyses is mass transfer theory from chemical engineering. The thrust of our work is to develop methods for predicting the performance of geologic repositories. The subjects treated in the present report are: radionuclide transport from a spherical-equivalent waste form through a backfill; analysis of radionuclide transport through a backfill using a non-linear sorption isotherm; radionuclide transport from a prolate spheroid-equivalent waste form with a backfill; radionuclide transport from a spherical-equivalent waste form through a backfill, where the solubility, diffusivity and retardation coefficients are temperature dependent; a coupled near-field, far-field analysis where dissolution and migration rates are temperature dependent; transport of radionuclides from a point source in a three-dimensional flow field; and a general solution for the transport of radioactive chains in geologic media. There are several important results from the numerical evaluations. First, radioactive decay, higher sorption in the rock and the backfill steepens the gradient for mass transfer, and lead to higher dissolution rates. This is contrary to what was expected by some other workers, but is shown clearly in the analytical solutions. Second, the backfill serves to provide sorption sites so that there is a delay in the arrival of radionuclides in the rock, although this effect is not so important for the steady-state transport of long-lived radionuclides.

  16. Numerical simulation of mass transport in internal solitary waves

    NASA Astrophysics Data System (ADS)

    Salloum, Maher; Knio, Omar M.; Brandt, Alan

    2012-01-01

    A computational study of mass transport by large-amplitude, mode-2 internal solitary waves propagating on a pycnocline between two layers of different densities was conducted. The numerical model is based on the simulation of a vorticity-based formulation of the two-dimensional Navier-Stokes equations in the Boussinesq limit. Numerical experiments are conducted of the collapse of an initially mixed region, which leads to the generation of a train of internal solitary waves. The peak wave amplitude, a, is achieved by the leading wave, which encloses an intrusional bulge. The wave amplitude decays as it moves away from the collapsing mixing region. When the amplitude drops below a critical value, the wave is no longer able to transport mass and sharp-nosed intrusion is left behind. Mass transport by the leading wave, and by the trailing wave train and intrusion, is analyzed by tracking the motion of Lagrangian particles initially concentrated in the mixed region. Results indicate that for moderate wave amplitudes, a gradual decay in the wave amplitude occurs as the wave propagates, but the structure of the bulge is essentially maintained during this process. In contrast, for large-amplitude waves, the motion around the bulge is substantially more complex, exhibiting periodic shedding of vortex structures in the wake of the bulge and entrainment of external fluid into its core. It is shown that these motions have substantial impact on mass transport by the wave train, which is quantified through detailed analysis of the Lagrangian particle distributions.

  17. Mass Transport Through Carbon Nanotube-Polystyrene Bundles

    NASA Astrophysics Data System (ADS)

    Lin, Rongzhou; Tran, Tuan

    2016-05-01

    Carbon nanotubes have been widely used as test channels to study nanofluidic transport, which has been found to have distinctive properties compared to transport of fluids in macroscopic channels. A long-standing challenge in the study of mass transport through carbon nanotubes (CNTs) is the determination of flow enhancement. Various experimental investigations have been conducted to measure the flow rate through CNTs, mainly based on either vertically aligned CNT membranes or individual CNTs. Here, we proposed an alternative approach that can be used to quantify the mass transport through CNTs. This is a simple method relying on the use of carbon nanotube-polystyrene bundles, which are made of CNTs pulled out from a vertically aligned CNT array and glued together by polystyrene. We experimentally showed by using fluorescent tagging that the composite bundles allowed measureable and selective mass transport through CNTs. This type of composite bundle may be useful in various CNT research areas as they are simple to fabricate, less likely to form macroscopic cracks, and offer a high density of CNT pores while maintaining the aligned morphology of CNTs.

  18. Direct observation of the symmetry breaking of the nanometer-scale local structure in the paraelectric cubic phase of BaTiO3 using convergent-beam electron diffraction

    NASA Astrophysics Data System (ADS)

    Tsuda, Kenji; Tanaka, Michiyoshi

    2016-07-01

    Nanometer-scale local structures of the cubic phase of barium titanate (BaTiO3) are investigated by convergent-beam electron diffraction (CBED) using a nanometer-size electron probe. Breaking of the cubic symmetry has been discovered in the nanometer-scale areas of the cubic phase. This indicates the existence of local polarization clusters as a precursor of the phase transition. Symmetry-breaking index maps for the fourfold rotation symmetry are given at different temperatures with the combined use of scanning transmission electron microscopy and CBED methods (STEM-CBED). A spatially hierarchical structure of the cubic phase is proposed, which may explain different local symmetries reported using different experimental probes.

  19. Optimal mass transport for shape matching and comparison.

    PubMed

    Su, Zhengyu; Wang, Yalin; Shi, Rui; Zeng, Wei; Sun, Jian; Luo, Feng; Gu, Xianfeng

    2015-11-01

    Surface based 3D shape analysis plays a fundamental role in computer vision and medical imaging. This work proposes to use optimal mass transport map for shape matching and comparison, focusing on two important applications including surface registration and shape space. The computation of the optimal mass transport map is based on Monge-Brenier theory, in comparison to the conventional method based on Monge-Kantorovich theory, this method significantly improves the efficiency by reducing computational complexity from O(n(2)) to O(n) . For surface registration problem, one commonly used approach is to use conformal map to convert the shapes into some canonical space. Although conformal mappings have small angle distortions, they may introduce large area distortions which are likely to cause numerical instability thus resulting failures of shape analysis. This work proposes to compose the conformal map with the optimal mass transport map to get the unique area-preserving map, which is intrinsic to the Riemannian metric, unique, and diffeomorphic. For shape space study, this work introduces a novel Riemannian framework, Conformal Wasserstein Shape Space, by combing conformal geometry and optimal mass transport theory. In our work, all metric surfaces with the disk topology are mapped to the unit planar disk by a conformal mapping, which pushes the area element on the surface to a probability measure on the disk. The optimal mass transport provides a map from the shape space of all topological disks with metrics to the Wasserstein space of the disk and the pullback Wasserstein metric equips the shape space with a Riemannian metric. We validate our work by numerous experiments and comparisons with prior approaches and the experimental results demonstrate the efficiency and efficacy of our proposed approach. PMID:26440265

  20. Mass transport by buoyant bubbles in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Pope, Edward C. D.; Babul, Arif; Pavlovski, Georgi; Bower, Richard G.; Dotter, Aaron

    2010-08-01

    We investigate the effect of three important processes by which active galactic nuclei (AGN)-blown bubbles transport material: drift, wake transport and entrainment. The first of these, drift, occurs because a buoyant bubble pushes aside the adjacent material, giving rise to a net upward displacement of the fluid behind the bubble. For a spherical bubble, the mass of upwardly displaced material is roughly equal to half the mass displaced by the bubble and should be ~ 107-9 Msolar depending on the local intracluster medium (ICM) and bubble parameters. We show that in classical cool-core clusters, the upward displacement by drift may be a key process in explaining the presence of filaments behind bubbles. A bubble also carries a parcel of material in a region at its rear, known as the wake. The mass of the wake is comparable to the drift mass and increases the average density of the bubble, trapping it closer to the cluster centre and reducing the amount of heating it can do during its ascent. Moreover, material dropping out of the wake will also contribute to the trailing filaments. Mass transport by the bubble wake can effectively prevent the buildup of cool material in the central galaxy, even if AGN heating does not balance ICM cooling. Finally, we consider entrainment, the process by which ambient material is incorporated into the bubble. Studies of observed bubbles show that they subtend an opening angle much larger than predicted by simple adiabatic expansion. We show that bubbles that entrain ambient material as they rise will expand faster than the adiabatic prediction; however, the entrainment rate required to explain the observed opening angle is large enough that the density contrast between the bubble and its surroundings would disappear rapidly. We therefore conclude that entrainment is unlikely to be a dominant mass transport process. Additionally, this also suggests that the bubble surface is much more stable against instabilities that promote

  1. Thermodynamically coupled mass transport processes in a saturated clay

    SciTech Connect

    Carnahan, C.L.

    1984-11-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table.

  2. Characterizing saturated mass transport in fractured cementitious materials

    NASA Astrophysics Data System (ADS)

    Akhavan, Alireza

    Concrete, when designed and constructed properly, is a durable material. However in aggressive environments concrete is prone to gradual deterioration which is due to penetration of water and aggressive agents (e.g., chloride ions) into concrete. As such, the rate of mass transport is the primary factor, controlling the durability of cementitious materials. Some level of cracking is inevitable in concrete due to brittle nature of the material. While mass transport can occur through concrete’s porous matrix, cracks can significantly accelerate the rate of mass transport and effectively influence the service life of concrete structures. To allow concrete service life prediction models to correctly account for the effect of cracks on concrete durability, mass transport thru cracks must be characterized. In this study, transport properties of cracks are measured to quantify the saturated hydraulic permeability and diffusion coefficient of cracks as a function of crack geometry (i.e.; crack width, crack tortuosity and crack wall roughness). Saturated permeability and diffusion coefficient of cracks are measured by constant head permeability test, electrical migration test, and electrical impedance spectroscopy. Plain and fiber reinforced cement paste and mortar as well as simulated crack samples are tested. The results of permeability test showed that the permeability of a crack is a function of crack width squared and can be predicted using Louis formula when crack tortuosity and surface roughness of the crack walls are accounted for. The results of the migration and impedance tests showed that the diffusion coefficient of the crack is not dependent on the crack width, but is primarily a function of volume fraction of cracks. The only parameter that is changing with the crack width is the crack connectivity. Crack connectivity was found to be linearly dependent on crack width for small crack and constant for large cracks (i.e.; approximately larger than 80 µm). The

  3. The role of mass transport in protein crystallization.

    PubMed

    García-Ruiz, Juan Manuel; Otálora, Fermín; García-Caballero, Alfonso

    2016-02-01

    Mass transport takes place within the mesoscopic to macroscopic scale range and plays a key role in crystal growth that may affect the result of the crystallization experiment. The influence of mass transport is different depending on the crystallization technique employed, essentially because each technique reaches supersaturation in its own unique way. In the case of batch experiments, there are some complex phenomena that take place at the interface between solutions upon mixing. These transport instabilities may drastically affect the reproducibility of crystallization experiments, and different outcomes may be obtained depending on whether or not the drop is homogenized. In diffusion experiments with aqueous solutions, evaporation leads to fascinating transport phenomena. When a drop starts to evaporate, there is an increase in concentration near the interface between the drop and the air until a nucleation event eventually takes place. Upon growth, the weight of the floating crystal overcomes the surface tension and the crystal falls to the bottom of the drop. The very growth of the crystal then triggers convective flow and inhomogeneities in supersaturation values in the drop owing to buoyancy of the lighter concentration-depleted solution surrounding the crystal. Finally, the counter-diffusion technique works if, and only if, diffusive mass transport is assured. The technique relies on the propagation of a supersaturation wave that moves across the elongated protein chamber and is the result of the coupling of reaction (crystallization) and diffusion. The goal of this review is to convince protein crystal growers that in spite of the small volume of the typical protein crystallization setup, transport plays a key role in the crystal quality, size and phase in both screening and optimization experiments. PMID:26841759

  4. The negative role of turbulence in estuarine mass transport

    NASA Astrophysics Data System (ADS)

    Nunes Vaz, Richard A.; Lennon, Geoffrey W.; de Silva Samarasinghe, Jayantha R.

    1989-04-01

    It is competition between the various stratifying and mixing influences which determines the character of stratification in an estuary. Borrowing concepts which have been successfully applied to the discussion of stratification in shelf seas, a quantitative basis for determining the potential energy associated with vertical structure in estuaries is derived. The formulation, along similar lines to that of Bowden (1981), provides a simple but comprehensive method of incorporating many relevant stratifying and mixing influences in a given problem, and is also shown to be capable of rearrangement into forms akin to the estuarine Richardson number which is commonly found in discussions of estuarine statification. The paper argues, based on a survey of the literature, that in wide, relatively well-mixed estuaries, the greatest longitudinal mass flux occurs at times when stratification is most developed, that is, when the turbulent kinetic energy in the water column is at a minimum. Modulation of turbulence, principally at various tidal frequencies, causes a pulsing of the mass flux in which the contribution of each pulse increases non-linearly as the period of the modulation increases. Some, possibly significant, changes to the state of stratification and to the corresponding mass transport may occur in association with slack water periods. However, the spring-neap cycle is proposed to have a far greater influence on stratification, mass transport and the long-term mass balance in estuaries, and recent observational studies lend support to this position.

  5. Optimum periodicity of repeated contractile actions applied in mass transport

    PubMed Central

    Ahn, Sungsook; Lee, Sang Joon

    2015-01-01

    Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications. PMID:25622949

  6. Optimum periodicity of repeated contractile actions applied in mass transport

    NASA Astrophysics Data System (ADS)

    Ahn, Sungsook; Lee, Sang Joon

    2015-01-01

    Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

  7. Miocene mass-transport sediments, Troodos Massif, Cyprus

    USGS Publications Warehouse

    Lord, A.R.; Harrison, R.W.; BouDagher-Fadel, M.; Stone, B.D.; Varol, O.

    2009-01-01

    Sediment mass-transport layers of submarine origin on the northern and southern flanks of the Troodos ophiolitic massif are dated biostratigraphically as early Miocene and late Miocene, respectively and therefore represent different seismogenic events in the uplift and erosional history of the Troodos terrane. Analysis of such events has potential for documenting Miocene seismic and uplift events regionally in the context of changing stress field directions and plate vectors through time. ?? 2009 The Geologists' Association.

  8. Rotational hydrodynamic diffusion system to study mass transport across boundaries.

    PubMed

    Mamidi, Sai Sree; Meas, Bo; Farhat, Tarek R

    2008-11-01

    The design and operation of a new mass transport technique is presented. Rotational hydrodynamic diffusion system (RHDS) is a method that can be adapted for analytical laboratory analysis as well as industrial-scale separation and purification. Although RHDS is not an electrochemical technique, its concept is derived from hydrodynamic rotating disk electrode voltammetry. A diffusion advantage gained using the RHDS is higher flux of probe molecules across the boundary (e.g., membrane or porous media) with increased rotation rate compared to the static two-half-cell (THC) method. The separation concept of RHDS differs from pressurized, agitated, electrodialysis, and reversed osmosis systems in design and theory. The detection mechanism of the RHDS opens the possibility to study mass transport properties of a large variety of molecules using different types of ultrathin membranes. Therefore, the RHDS is a potential alternative to classical mass transport detection methods such as THC, impedance spectroscopy, and cyclic and rotating disk electrode voltammetry. Theoretical analysis on the rotational hydrodynamic flux is derived and compared to experimental flux measured using HCl, KCl, KNO 3, Ni(NO 3) 2, LiCl, camphor sulfonic acid, and K 3Fe(CN) 6 ionic solutions. Values of effective diffusion coefficients of salts across Nucleopore membranes of thickness 6.0 and 10 mum with pore size 0.1 and 0.2 mum, respectively, are presented and discussed. PMID:18844370

  9. Vortical ciliary flows actively enhance mass transport in reef corals

    PubMed Central

    Shapiro, Orr H.; Fernandez, Vicente I.; Garren, Melissa; Guasto, Jeffrey S.; Debaillon-Vesque, François P.; Kramarsky-Winter, Esti; Vardi, Assaf; Stocker, Roman

    2014-01-01

    The exchange of nutrients and dissolved gasses between corals and their environment is a critical determinant of the growth of coral colonies and the productivity of coral reefs. To date, this exchange has been assumed to be limited by molecular diffusion through an unstirred boundary layer extending 1–2 mm from the coral surface, with corals relying solely on external flow to overcome this limitation. Here, we present direct microscopic evidence that, instead, corals can actively enhance mass transport through strong vortical flows driven by motile epidermal cilia covering their entire surface. Ciliary beating produces quasi-steady arrays of counterrotating vortices that vigorously stir a layer of water extending up to 2 mm from the coral surface. We show that, under low ambient flow velocities, these vortices, rather than molecular diffusion, control the exchange of nutrients and oxygen between the coral and its environment, enhancing mass transfer rates by up to 400%. This ability of corals to stir their boundary layer changes the way that we perceive the microenvironment of coral surfaces, revealing an active mechanism complementing the passive enhancement of transport by ambient flow. These findings extend our understanding of mass transport processes in reef corals and may shed new light on the evolutionary success of corals and coral reefs. PMID:25192936

  10. RWPV bioreactor mass transport: earth-based and in microgravity

    NASA Technical Reports Server (NTRS)

    Begley, Cynthia M.; Kleis, Stanley J.

    2002-01-01

    Mass transport and mixing of perfused scalar quantities in the NASA Rotating Wall Perfused Vessel bioreactor are studied using numerical models of the flow field and scalar concentration field. Operating conditions typical of both microgravity and ground-based cell cultures are studied to determine the expected vessel performance for both flight and ground-based control experiments. Results are presented for the transport of oxygen with cell densities and consumption rates typical of colon cancer cells cultured in the RWPV. The transport and mixing characteristics are first investigated with a step change in the perfusion inlet concentration by computing the time histories of the time to exceed 10% inlet concentration. The effects of a uniform cell utilization rate are then investigated with time histories of the outlet concentration, volume average concentration, and volume fraction starved. It is found that the operating conditions used in microgravity produce results that are quite different then those for ground-based conditions. Mixing times for microgravity conditions are significantly shorter than those for ground-based operation. Increasing the differential rotation rates (microgravity) increases the mixing and transport, while increasing the mean rotation rate (ground-based) suppresses both. Increasing perfusion rates enhances mass transport for both microgravity and ground-based cases, however, for the present range of operating conditions, above 5-10 cc/min there are diminishing returns as much of the inlet fluid is transported directly to the perfusion exit. The results show that exit concentration is not a good indicator of the concentration distributions in the vessel. In microgravity conditions, the NASA RWPV bioreactor with the viscous pump has been shown to provide an environment that is well mixed. Even when operated near the theoretical minimum perfusion rates, only a small fraction of the volume provides less than the required oxygen levels

  11. A global assessment of accelerations in surface mass transport

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoping; Heflin, Michael B.

    2015-08-01

    Water mass transport in the Earth's dynamic surface layer of atmosphere, cryosphere, and hydrosphere driven by various global change processes has complex spatiotemporal patterns. Here we determine global patterns and regional mean values of accelerations in surface mass variations during the Gravity Recovery and Climate Experiment (GRACE) mission's data span from 2002.2 to 2015.0. GRACE gravity data are supplemented by surface deformation from 607 Global Navigation Satellite System stations, an ocean bottom pressure model, satellite laser ranging, and loose a priori knowledge on mass variation regimes incorporating high-resolution geographic boundaries. While Greenland and West Antarctica have strong negative accelerations, Alaska and the Arctic Ocean show significant positive accelerations. In addition, the accelerations are not constant in time with some regions showing considerable variability due to irregular interannual changes. No evidence of significant nonsteric mean sea level acceleration has been found, but the uncertainty is quite large.

  12. On Matrix-Valued Monge–Kantorovich Optimal Mass Transport

    PubMed Central

    Ning, Lipeng; Georgiou, Tryphon T.; Tannenbaum, Allen

    2016-01-01

    We present a particular formulation of optimal transport for matrix-valued density functions. Our aim is to devise a geometry which is suitable for comparing power spectral densities of multivariable time series. More specifically, the value of a power spectral density at a given frequency, which in the matricial case encodes power as well as directionality, is thought of as a proxy for a “matrix-valued mass density.” Optimal transport aims at establishing a natural metric in the space of such matrix-valued densities which takes into account differences between power across frequencies as well as misalignment of the corresponding principle axes. Thus, our transportation cost includes a cost of transference of power between frequencies together with a cost of rotating the principle directions of matrix densities. The two endpoint matrix-valued densities can be thought of as marginals of a joint matrix-valued density on a tensor product space. This joint density, very much as in the classical Monge–Kantorovich setting, can be thought to specify the transportation plan. Contrary to the classical setting, the optimal transport plan for matrices is no longer supported on a thin zero-measure set. PMID:26997667

  13. Updated Delft Mass Transport model DMT-2: computation and validation

    NASA Astrophysics Data System (ADS)

    Hashemi Farahani, Hassan; Ditmar, Pavel; Inacio, Pedro; Klees, Roland; Guo, Jing; Guo, Xiang; Liu, Xianglin; Zhao, Qile; Didova, Olga; Ran, Jiangjun; Sun, Yu; Tangdamrongsub, Natthachet; Gunter, Brian; Riva, Ricardo; Steele-Dunne, Susan

    2014-05-01

    A number of research centers compute models of mass transport in the Earth's system using primarily K-Band Ranging (KBR) data from the Gravity Recovery And Climate Experiment (GRACE) satellite mission. These models typically consist of a time series of monthly solutions, each of which is defined in terms of a set of spherical harmonic coefficients up to degree 60-120. One of such models, the Delft Mass Transport, release 2 (DMT-2), is computed at the Delft University of Technology (The Netherlands) in collaboration with Wuhan University. An updated variant of this model has been produced recently. A unique feature of the computational scheme designed to compute DMT-2 is the preparation of an accurate stochastic description of data noise in the frequency domain using an Auto-Regressive Moving-Average (ARMA) model, which is derived for each particular month. The benefits of such an approach are a proper frequency-dependent data weighting in the data inversion and an accurate variance-covariance matrix of noise in the estimated spherical harmonic coefficients. Furthermore, the data prior to the inversion are subject to an advanced high-pass filtering, which makes use of a spatially-dependent weighting scheme, so that noise is primarily estimated on the basis of data collected over areas with minor mass transport signals (e.g., oceans). On the one hand, this procedure efficiently suppresses noise, which are caused by inaccuracies in satellite orbits and, on the other hand, preserves mass transport signals in the data. Finally, the unconstrained monthly solutions are filtered using a Wiener filter, which is based on estimates of the signal and noise variance-covariance matrices. In combination with a proper data weighting, this noticeably improves the spatial resolution of the monthly gravity models and the associated mass transport models.. For instance, the computed solutions allow long-term negative trends to be clearly seen in sufficiently small regions notorious

  14. Metal intercalation-induced selective adatom mass transport on graphene

    DOE PAGESBeta

    Liu, Xiaojie; Wang, Cai -Zhuang; Hupalo, Myron; Lin, Hai -Qing; Ho, Kai -Ming; Thiel, Patricia A.; Tringides, Michael C.

    2016-03-29

    Recent experiments indicate that metal intercalation is a very effective method to manipulate the graphene-adatom interaction and control metal nanostructure formation on graphene. A key question is mass transport, i.e., how atoms deposited uniformly on graphene populate different areas depending on the local intercalation. Using first-principles calculations, we show that partially intercalated graphene, with a mixture of intercalated and pristine areas, can induce an alternating electric field because of the spatial variations in electron doping, and thus, an oscillatory electrostatic potential. As a result, this alternating field can change normal stochastic adatom diffusion to biased diffusion, leading to selective massmore » transport and consequent nucleation, on either the intercalated or pristine areas, depending on the charge state of the adatoms.« less

  15. Angular momentum transport within evolved low-mass stars

    SciTech Connect

    Cantiello, Matteo; Bildsten, Lars; Paxton, Bill; Mankovich, Christopher; Christensen-Dalsgaard, Jørgen

    2014-06-10

    Asteroseismology of 1.0-2.0 M {sub ☉} red giants by the Kepler satellite has enabled the first definitive measurements of interior rotation in both first ascent red giant branch (RGB) stars and those on the helium burning clump. The inferred rotation rates are 10-30 days for the ≈0.2 M {sub ☉} He degenerate cores on the RGB and 30-100 days for the He burning core in a clump star. Using the Modules for Experiments in Stellar Evolution code, we calculate state-of-the-art stellar evolution models of low mass rotating stars from the zero-age main sequence to the cooling white dwarf (WD) stage. We include transport of angular momentum due to rotationally induced instabilities and circulations, as well as magnetic fields in radiative zones (generated by the Tayler-Spruit dynamo). We find that all models fail to predict core rotation as slow as observed on the RGB and during core He burning, implying that an unmodeled angular momentum transport process must be operating on the early RGB of low mass stars. Later evolution of the star from the He burning clump to the cooling WD phase appears to be at nearly constant core angular momentum. We also incorporate the adiabatic pulsation code, ADIPLS, to explicitly highlight this shortfall when applied to a specific Kepler asteroseismic target, KIC8366239.

  16. Mass Flux of ZnSe by Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Sha, Yi-Gao; Su, Ching-Hua; Palosz, W.; Volz, M. P.; Gillies, D. C.; Szofran, F. R.; Lehoczky, S. L.; Liu, Hao-Chieh; Brebrick, R. F.

    1995-01-01

    Mass fluxes of ZnSe by physical vapor transport (PVT) were measured in the temperature range of 1050 to 1160 C using an in-situ dynamic technique. The starting materials were either baked out or distilled under vacuum to obtain near-congruently subliming compositions. Using an optical absorption technique Zn and Se, were found to be the dominant vapor species. Partial pressures of Zn and Se, over the starting materials at temperatures between 960 and 1140 C were obtained by measuring the optical densities of the vapor phase at the wavelengths of 2138, 3405, 3508, 3613, and 3792 A. The amount and composition of the residual gas inside the experimental ampoules were measured after the run using a total pressure gauge. For the first time, the experimentally determined partial pressures of Zn and Se, and the amount and composition of the residual gas were used in a one-dimensional diffusion limited analysis of the mass transport rates for a PVT system. Reasonable agreement between the experimental and theoretical results was observed.

  17. Experimental Studies on Mass Transport of Cadmium-Zinc Telluride by Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Szofran, F. R.; Lehoczky, S. L.

    1995-01-01

    Experimental studies on mass transport of ternary compound, Cd(1-x)Zn(x)Te by physical vapor transport (PVT) for source compositions up to X = 0.21 are presented. The effect of thermochemical (temperatures, vapor composition) and other factors (preparation of the source, crystal growth rate, temperature gradient) on composition and composition profiles of the grown crystals were investigated. A steep decrease in the mass flux with an increase in X(crystal) for X less than 0.1, and a difference in composition between the source and the deposited material have been observed. The composition profiles of the crystals were found to depend on the density and pretreatment of the source, and on the temperature gradient in the source zone. The homogeneity of the crystals improves at low undercoolings and/or when an appropriate excess of metal constituents is present in the vapor phase. The experimental results are in good agreement with our thermochemical model of this system.

  18. Dusty air masses transport between Amazon Basin and Caribbean Islands

    NASA Astrophysics Data System (ADS)

    Euphrasie-Clotilde, Lovely; Molinie, Jack; Prospero, Joseph; Feuillard, Tony; Brute, Francenor; Jeannot, Alexis

    2015-04-01

    Depend on the month, African desert dust affect different parts of the North Atlantic Ocean. From December to April, Saharan dust outbreaks are often reported over the amazon basin and from May to November over the Caribbean islands and the southern regions of USA. This annual oscillation of Saharan dust presence, related to the ITCZ position, is perturbed some time, during March. Indeed, over Guadeloupe, the air quality network observed between 2007 and 2012 several dust events during March. In this paper, using HISPLIT back trajectories, we analyzed air masses trajectories for March dust events observed in Guadeloupe, from 2007 to 2012.We observed that the high pressure positions over the Atlantic Ocean allow the transport of dusty air masses from southern region of West Africa to the Caribbean Sea with a path crossing close to coastal region of French Guyana. Complementary investigations including the relationship between PM10 concentrations recorded in two sites Pointe-a-Pitre in the Caribbean, and Cayenne in French Guyana, have been done. Moreover we focus on the mean delay observed between the times arrival. All the results show a link between pathway of dusty air masses present over amazon basin and over the Caribbean region during several event of March. The next step will be the comparison of mineral dust composition for this particular month.

  19. Microwave sintering of MoSi{sub 2}-Mo{sub 5}Si{sub 3} to promote a final nanometer-scale microstructure and suppressing of pesting phenomenon

    SciTech Connect

    Arreguin-Zavala, J. Turenne, S.; Martel, A.; Benaissa, A.

    2012-06-15

    This work shows an innovative sintering process for molybdenum disilicide (MoSi{sub 2}) and molybdenum silicide (Mo{sub 5}Si{sub 3}) in order to have a final nanometer-scale microstructure. Sintered MoSi{sub 2}-Mo{sub 5}Si{sub 3} was fabricated by microwave sintering. The final material showed a significant reduction of pesting phenomena for MoSi{sub 2}. The final microstructure is a mix of micrometer-scale MoSi{sub 2} and nanometer-scale Mo{sub 5}Si{sub 3} immersed in an amorphous SiO{sub 2} phase. This material was characterized by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermal Gravimetric Analysis (TGA). - Highlights: Black-Right-Pointing-Pointer We sintered the MoSi{sub 2}-Mo{sub 5}Si{sub 3} by microwave and obtained high final density material. Black-Right-Pointing-Pointer We got a final nanostructured material. Black-Right-Pointing-Pointer We inhibited pesting phenomenon for MoSi{sub 2}.

  20. Mass transport measurements and modeling for chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Chiang, D.Y.; Fiadzo, O.G.; Hablutzel, N.

    1997-12-01

    This project involves experimental and modeling investigation of densification behavior and mass transport in fiber preforms and partially densified composites, and application of these results to chemical vapor infiltration (CVI) process modeling. This supports work on-going at ORNL in process development for fabrication of ceramic matrix composite (CMC) tubes. Tube-shaped composite preforms are fabricated at ORNL with Nextel{trademark} 312 fiber (3M Corporation, St. Paul, MN) by placing and compressing several layers of braided sleeve on a tubular mandrel. In terms of fiber architecture these preforms are significantly different than those made previously with Nicalon{trademark} fiber (Nippon Carbon Corp., Tokyo, Japan) square weave cloth. The authors have made microstructure and permeability measurements on several of these preforms and a few partially densified composites so as to better understand their densification behavior during CVI.

  1. Restricted mass transport effects on free radical reactions

    NASA Astrophysics Data System (ADS)

    Buchanan, A. C., III; Britt, P. F.; Thomas, K. B.

    Coal possesses a complex chemical and physical structure. The cross-linked, network structure can lead to alterations in normal thermally-induced, free-radical decay pathways as a consequence of restrictions on mass transport. Moreover, in coal liquefaction, access of an external hydrogen donor to a reactive radical site can be hindered by the substantial domains of microporosity present in coals. However, previous work indicates that diffusion effects do not appear to be playing an important role in this coal conversion chemistry. Several possible explanations for this phenomenon were advanced including the potential involvement of a hydrogen hopping/radical relay mechanism recently discovered model systems in the authors' laboratories. The authors have employed silica-anchored compounds to explore the effects of restricted mass transport on the pyrolysis mechanisms of coal model compounds. In studies of two-component systems, cases have been discovered where radical centers can be rapidly relocated in the diffusionally constrained environment as a consequence of rapid serial hydrogen atom transfers. This chemistry can have substantial effects on thermal decomposition rates and on product selectivities. In this study, the authors examine additional surfaces to systematically investigate the impact of molecular structure on the hydrogen atom transfer promoted radical relay mechanism. Silica-attached 1,3-diphenylpropane (approximately Ph(CH2)3Ph, or approximately DPP) was chosen as the thermally reactive component, since it can be considered prototypical of linkages in coal that do not contain weak bonds easily cleaved at coal liquefaction temperatures (ca. 4000 C), but which crack at reasonable rates if benzylic radicals can be generated by hydrogen abstraction. The rate of such hydrogen transfers under restricted diffusion will be highly dependent on the structure and proximity of neighboring molecules.

  2. Density Functional Theory Calculations of Mass Transport in UO2

    SciTech Connect

    Andersson, Anders D.; Dorado, Boris; Uberuaga, Blas P.; Stanek, Christopher R.

    2012-06-26

    In this talk we present results of density functional theory (DFT) calculations of U, O and fission gas diffusion in UO{sub 2}. These processes all impact nuclear fuel performance. For example, the formation and retention of fission gas bubbles induce fuel swelling, which leads to mechanical interaction with the clad thereby increasing the probability for clad breach. Alternatively, fission gas can be released from the fuel to the plenum, which increases the pressure on the clad walls and decreases the gap thermal conductivity. The evolution of fuel microstructure features is strongly coupled to diffusion of U vacancies. Since both U and fission gas transport rates vary strongly with the O stoichiometry, it is also important to understand O diffusion. In order to better understand bulk Xe behavior in UO{sub 2{+-}x} we first calculate the relevant activation energies using DFT techniques. By analyzing a combination of Xe solution thermodynamics, migration barriers and the interaction of dissolved Xe atoms with U, we demonstrate that Xe diffusion predominantly occurs via a vacancy-mediated mechanism. Since Xe transport is closely related to diffusion of U vacancies, we have also studied the activation energy for this process. In order to explain the low value of 2.4 eV found for U migration from independent damage experiments (not thermal equilibrium) the presence of vacancy clusters must be included in the analysis. Next we investigate species transport on the (111) UO{sub 2} surface, which is motivated by the formation of small voids partially filled with fission gas atoms (bubbles) in UO{sub 2} under irradiation. Surface diffusion could be the rate-limiting step for diffusion of such bubbles, which is an alternative mechanism for mass transport in these materials. As expected, the activation energy for surface diffusion is significantly lower than for bulk transport. These results are further discussed in terms of engineering-scale fission gas release models

  3. Materials with engineered mesoporosity for programmed mass transport

    NASA Astrophysics Data System (ADS)

    Gough, Dara V.

    Transport in nanostructured materials is of great interest for scientists in various fields, including molecular sequestration, catalysis, artificial photosynthesis and energy storage. This thesis will present work on the transport of molecular and ionic species in mesoporous materials (materials with pore sizes between 2 and 50 nm). Initially, discussion will focus on the synthesis of mesoporous ZnS nanorattles and the size selected mass transport of small molecules through the mesopores. Discussion will then shift of exploration of cation exchange and electroless plating of metals to alter the mesoporous hollow sphere (MHS) materials and properties. The focus of discussion will then shift to the transport of ions into and out of a hierarchically structured gold electrode. Finally, a model gamma-bactiophage was developed to study the electromigration of charged molecules into and out of a confined geometry. A catalytically active biomolecular species was encapsulated within the central cavity of ZnS MHS. Both the activity of the encapsulated enzyme and the size-selective transport through the wall of the MHS were verified through the use of a common fluorogen, hydrogen peroxide, and sodium azide. Additionally, the protection of the enzyme was shown through size-selected blocking of a protease. The mesoporous hollow sphere system introduces size-selectivity to catalyzed chemical reactions; future work may include variations in pore sizes, and pore wall chemical functionalization. The pore size in ZnS mesoporous hollow spheres is controlled between 2.5 and 4.1 nm through swelling of the lyotropic liquid crystal template. The incorporation of a swelling agent is shown to linearly vary the hexagonal lyotropic liquid crystalline phase, which templates the mesopores, while allowing the high fidelity synthesis of mesoporous hollow spheres. Fluorescnently labeled ssDNA was utilized as a probe to explore the change in mesopore permeability afforded by the swollen template

  4. Dynamic characterization of external and internal mass transport in heterotrophic biofilms from microsensors measurements.

    PubMed

    Guimerà, Xavier; Dorado, Antonio David; Bonsfills, Anna; Gabriel, Gemma; Gabriel, David; Gamisans, Xavier

    2016-10-01

    Knowledge of mass transport mechanisms in biofilm-based technologies such as biofilters is essential to improve bioreactors performance by preventing mass transport limitation. External and internal mass transport in biofilms was characterized in heterotrophic biofilms grown on a flat plate bioreactor. Mass transport resistance through the liquid-biofilm interphase and diffusion within biofilms were quantified by in situ measurements using microsensors with a high spatial resolution (<50 μm). Experimental conditions were selected using a mathematical procedure based on the Fisher Information Matrix to increase the reliability of experimental data and minimize confidence intervals of estimated mass transport coefficients. The sensitivity of external and internal mass transport resistances to flow conditions within the range of typical fluid velocities over biofilms (Reynolds numbers between 0.5 and 7) was assessed. Estimated external mass transfer coefficients at different liquid phase flow velocities showed discrepancies with studies considering laminar conditions in the diffusive boundary layer near the liquid-biofilm interphase. The correlation of effective diffusivity with flow velocities showed that the heterogeneous structure of biofilms defines the transport mechanisms inside biofilms. Internal mass transport was driven by diffusion through cell clusters and aggregates at Re below 2.8. Conversely, mass transport was driven by advection within pores, voids and water channels at Re above 5.6. Between both flow velocities, mass transport occurred by a combination of advection and diffusion. Effective diffusivities estimated at different biofilm densities showed a linear increase of mass transport resistance due to a porosity decrease up to biofilm densities of 50 g VSS·L(-1). Mass transport was strongly limited at higher biofilm densities. Internal mass transport results were used to propose an empirical correlation to assess the effective diffusivity

  5. Multigrid optimal mass transport for image registration and morphing

    NASA Astrophysics Data System (ADS)

    Rehman, Tauseef ur; Tannenbaum, Allen

    2007-02-01

    In this paper we present a computationally efficient Optimal Mass Transport algorithm. This method is based on the Monge-Kantorovich theory and is used for computing elastic registration and warping maps in image registration and morphing applications. This is a parameter free method which utilizes all of the grayscale data in an image pair in a symmetric fashion. No landmarks need to be specified for correspondence. In our work, we demonstrate significant improvement in computation time when our algorithm is applied as compared to the originally proposed method by Haker et al [1]. The original algorithm was based on a gradient descent method for removing the curl from an initial mass preserving map regarded as 2D vector field. This involves inverting the Laplacian in each iteration which is now computed using full multigrid technique resulting in an improvement in computational time by a factor of two. Greater improvement is achieved by decimating the curl in a multi-resolutional framework. The algorithm was applied to 2D short axis cardiac MRI images and brain MRI images for testing and comparison.

  6. Mass transport and element mobilisation during large-scale metasomatism

    NASA Astrophysics Data System (ADS)

    Putnis, C. V.; Austrheim, H.; Jamtveit, B.; Engvik, A. K.; Putnis, A.

    2009-04-01

    Replacement textures commonly occur in relation to fluid-driven large scale metasomatism and metamorphism and these processes are often related to mineralisation. For example, the albitisation of gabbroic rocks in the Bamble District, southern Norway is associated with ore deposits. Similar albitised rocks are also characteristic of the Curnamona Province, Australia, which includes large areas of mineralisation such as the Pb, Zn, Ag of the Broken Hill deposits as well as Cu, Au and U deposits. The main question addressed here is the mechanism of mass transport and hence element mobilisation. An indication of the former presence of fluids within a rock can be seen in mineral textures, such as porosity, replacement rims, replacement induced fracturing and crystallographic continuity across sharp compositional boundaries. Such textural observations from natural rocks as well as experimental products show that during mineral-fluid interaction, the crystallographic relations between parent and product phases control the nucleation of the product, and hence a coupling between dissolution and reprecipitation. If the rate of nucleation and growth of the product equals the dissolution rate, a pseudomorphic replacement takes place. The degree of epitaxy (or lattice misfit) at the interface, the relative solubility of parent and product phases and the molar volume changes control the microstructure of the product phase. The key observation is that these factors control the generation of porosity as well as reaction induced fracturing ahead of the main reaction interface. Porosity is generated whenever the amount of parent dissolved is greater than the amount of product reprecipitated, irrespective of the molar volume changes of the solid reactants and products. This porosity is occupied by the fluid phase during the reaction, and provides a mechanism of mass transport and fluid movement between reaction interface and the surrounding phases. The reaction-induced fracturing

  7. Turbulence and mass-transports in stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Ghate, Virendra P.

    Boundary layer (BL) stratocumulus clouds are an important factor in the earth's radiation budget due to their high albedo and low cloud top heights. Continental BL stratocumulus clouds are closely coupled to the diurnal cycle and the turbulence in the BL affecting the surface energy and moisture budgets. In this study the turbulence and mass-transport structures in continental BL stratocumulus clouds are studied using data from the Atmospheric Radiation Measurements (ARM)'s Southern Great Plains (SGP) observing facility located at Lamont, Oklahoma. High temporal (4 sec) and spatial (45 m) resolution observations from a vertically pointing 35 GHz cloud Doppler radar were used to obtain the in-cloud vertical velocity probability density function (pdf) in the absence of precipitation size hydrometeors. A total of 70 hours of radar data were analyzed to report half-hourly statistics of vertical velocity variance, skewness, updraft fraction, downdraft and velocity binned mass-flux at five cloud depth normalized levels. The variance showed a general decrease with increase in height in the cloud layer while the skewness is weakly positive in the cloud layer and negative near cloud top. The updraft fraction decreases with height with the decrease mainly occurring in the upper half of the cloud layer. The downdraft fraction increases with decrease in height with the increase being almost linear. The velocity of eddies responsible for maximum mass-transport decreases from of 0.4 ms-1 near cloud base to 0.2 ms-1 near cloud top. The half-hour periods were then classified based on the surface buoyancy flux as stable or unstable and it was found that the variance near cloud top is higher during the stable periods as compared to the unstable periods. Classification was also made based on the cloud depth to BL depth ratio (CBR) being greater or less than 0.3. The variance profile was similar for the classification while the skewness was almost zero during periods with CBR less 0

  8. Mass transport analysis in the near field of geologic repository

    NASA Astrophysics Data System (ADS)

    Lim, Doo-Hyun

    A two-dimensional model for the groundwater flow and the contaminant transport has been developed. A water-saturated, deep geologic repository for high-level radioactive wastes (HLW) is considered. The region containing a waste canister, a backfill material around the canister, and the near-field rock (NFR) surrounding the backfill is considered. Discrete-Fracture Network (DFN) is generated in the NFR based on distribution functions of the fracture geometry parameters by random sampling. Flow-bearing fracture network is identified, and is transformed into an equivalent continuous porous medium in two different ways without calculating flow rates through individual fractures. The first transformation is applied locally, generating a heterogeneous porous medium. The second transformation is applied for the entire NFR, resulting in a homogeneous porous medium. While the heterogeneous porous medium is considered to represent characteristics of water flow in DFN better than the homogeneous porous medium, the homogeneous porous medium was often used in previous performance assessment studies for its simplicity. After these transformations, the spatial distribution of groundwater flow rate is calculated by a finite element method. The numerical results for the total discharge at the outer boundary of the homogenized NFR after the second transformation are benchmarked by analytical solutions with a relative difference smaller than 0.55%. The contaminant transport is simulated by a random-walk particle-tracking method, based on the obtained flow-rate distribution. Previous study for a step equation that determines the movement of contaminant particles has been critically reviewed. Numerical results obtained by the first and second transformations have been compared. The second transformation gives smaller mean values of the residence time of particles in the NFR and greater mean values of the mass absorption rate at the outer boundary of NFR than the first one does. Thus

  9. Mass spectrometry on the nanoscale with ion sputtering based techniques: What is feasible

    NASA Astrophysics Data System (ADS)

    Veryovkin, Igor V.; Calaway, Wallis F.; Tripa, C. Emil; Pellin, Michael J.

    2007-08-01

    The potential of ion sputtering based mass spectrometry applied to materials characterization on the nanometer scale is discussed. Analytical approaches and required instrumental capabilities are outlined, and the current state-of-the-art is summarized. A new generation of analytical instruments specifically optimized for laser post-ionization secondary neutral mass spectrometry has been developed at Argonne National Laboratory (ANL). Experimentally verified (or anticipated after near-future upgrades) analytical capabilities of these instruments, capable of quantitative analysis at the nanometer-scale, are reported and compared to secondary ion mass spectrometry.

  10. A Mercury Transport and Fate Model for Mass Budget Assessment of Mercury Cycling in Lake Michigan

    EPA Science Inventory

    A mercury mass balance model was developed to describe and evaluate the fate, transport, and biogeochemical transformations of mercury in Lake Michigan. Coupling with total suspendable solids (TSS) and dissolved organic carbon (DOC), the mercury transport and fate model simulates...

  11. Mass transport, faceting and behavior of dislocations in GaN

    SciTech Connect

    Nitta, S.; Kashima, T.; Kariya, M.; Yukawa, Y.; Yamaguchi, S.; Amano, H.; Akasaki, I.

    2000-07-01

    The behavior of threading dislocations during mass transport of GaN was investigated in detail by transmission electron microscopy. Mass transport occurred at the surface. Therefore, growing species are supplied from the in-plane direction. The behavior of threading dislocations was found to be strongly affected by the mass transport process as well as the high crystallographic anisotropy of the surface energy of the facets particular to GaN.

  12. The latent fingerprint in mass transport of polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Thirunavukarasu, Gopinath; Kundu, Sukumar; Chatterjee, Subrata

    2016-02-01

    Herein, a systematic investigation was carried out to reach a rational understanding and to provide information concerning the possible causes for a significant influence of pressure variation in the underlying processes of mass transport in polycrystalline materials. The authors focused their research in solid-state diffusion, a part of the subject "Mass Transport in Solids". Theories on diffusion are the subject by itself which exists as a latent fingerprint in every text of higher learning in interdisciplinary science. In this research, authors prepared sandwich samples of titanium alloy and stainless steel using nickel as an intermediate metal. The samples were processed at three different levels of bonding pressure (3, 4 and 5 MPa) while bonding temperature and bonding time was maintained at 750 °C and 1 h, respectively, throughout the experiments. It was observed that the net flux of atomic diffusion of nickel atoms into Ti-alloy at TiA/Ni interface increased by ~63 % with the rise in the bonding pressure from 3 to 4 MPa, but decreased by ~40 % with the rise in the bonding pressure from 4 to 5 MPa. At the same time, the net flux of atomic diffusion of nickel atoms into stainless steel at Ni/SS interface increased by ~19 % with the rise in the bonding pressure from 3 to 4 MPa, but increased by ~17 % with the rise in the bonding pressure from 4 to 5 MPa. Here authors showed that the pressure variations have different effects at the TiA/Ni interface and Ni/SS interface, and tried to explain the explicit mechanisms operating behind them. In general for sandwich samples processed irrespective of bonding pressure chosen, the net flux of Ni-atoms diffused into SS is greater than that of the net flux of Ni-atoms diffused in Ti-alloy matrix by four orders of magnitude. The calculated diffusivity of Ni-atoms into Ti-alloy reaches its highest value of ~5.083 × 10-19 m2/s for the sandwich sample processed using 4-MPa bonding-pressure, whereas the diffusivity of Ni

  13. Theoretical monochromatic-wave-induced currents in intermediate water with viscosity and nonzero mass transport

    NASA Technical Reports Server (NTRS)

    Talay, T. A.

    1975-01-01

    Wave-induced mass-transport current theories with both zero and nonzero net mass (or volume) transport of the water column are reviewed. A relationship based on the Longuet-Higgens theory is derived for wave-induced, nonzero mass-transport currents in intermediate water depths for a viscous fluid. The relationship is in a form useful for experimental applications; therefore, some design criteria for experimental wave-tank tests are also presented. Sample parametric cases for typical wave-tank conditions and a typical ocean swell were assessed by using the relation in conjunction with an equation developed by Unluata and Mei for the maximum wave-induced volume transport. Calculations indicate that substantial changes in the wave-induced mass-transport current profiles may exist dependent upon the assumed net volume transport. A maximum volume transport, corresponding to an infinite channel or idealized ocean condition, produces the largest wave-induced mass-transport currents. These calculations suggest that wave-induced mass-transport currents may have considerable effects on pollution and suspended-sediments transport as well as buoy drift, the surface and midlayer water-column currents caused by waves increasing with increasing net volume transports. Some of these effects are discussed.

  14. Magnetoelastic sensors in combination with nanometer-scale honeycombed thin film ceramic TiO2 for remote query measurement of humidity

    NASA Technical Reports Server (NTRS)

    Grimes, C. A.; Kouzoudis, D.; Dickey, E. C.; Qian, D.; Anderson, M. A.; Shahidain, R.; Lindsey, M.; Green, L.

    2000-01-01

    Ribbonlike magnetoelastic sensors can be considered the magnetic analog of an acoustic bell; in response to an externally applied magnetic field impulse the sensors emit magnetic flux with a characteristic resonant frequency. The magnetic flux can be detected external to the test area using a pick-up coil, enabling query remote monitoring of the sensor. The characteristic resonant frequency of a magnetoelastic sensor changes in response to mass loads. [L.D. Landau and E. M. Lifshitz, Theory of Elasticity, 3rd ed. (Pergamon, New York, 1986). p. 100].Therefore, remote query chemical sensors can be fabricated by combining the magnetoelastic sensors with a mass changing, chemically responsive layer. In this work magnetoelastic sensors are coated with humidity-sensitive thin films of ceramic, nanodimensionally porous TiO2 to make remote query humidity sensors. c2000 American Institute of Physics.

  15. Transport dynamics of mass failures along weakly cohesive clinoform foresets

    NASA Astrophysics Data System (ADS)

    Abeyta, A.; Paola, C.

    2012-12-01

    The initiation mechanisms of sediment gravity flows are poorly understood. Previous studies have created sediment gravity flows by releasing dense water-sediment mixtures into ambient water. One limitation to these studies is that the slurries are premixed and are injected into the water column such that the initial properties of the flow - density, composition and momentum flux - are predetermined. This precludes observation of the processes that initiate the flows and set these initial conditions. As a result, there is a gap in our understanding of how submarine gravity flows initiate and what sets their initial conditions. Here we use a new experimental method that allows a range of gravity flows to self-generate. Building a clinoform using a cohesive mixture of walnut-shell sand and kaolinte, allows the foreset to build up and fail episodically, generating spontaneous sediment gravity flows. Slopes undergo a series of morphological changes prior to failure. The slope develops a concave shape that becomes exaggerated as deposition continues. This morphology leaves the slope in a metastable state. Either of two mechanisms triggers destabilization of the slope: slumping or bed-load transport. Once the slope is destabilized, failure is initiated. We also investigated the influence of clinoform progradation rates on failure size and frequency. We conducted experiments over a range of water and sediment discharge rates (0.007 to 0.036 liters of water per second, 0.50 to 1.28 g/s sediment). Neither failure size nor failure frequency changes with discharge rate; instead, increases in sediment supply are taken up by changes in the partitioning of sediment between the steep upper foreset and the more gradual delta-front apron below. Sediment is delivered to the delta-front apron by a form of semi-continuous slow creep along the foreset. This slow creep is a failure mode that has been under-appreciated in the submarine mass-flow literature. The independence of failure

  16. MASS TRANSPORT EFFECTS ON THE KINETICS OF NITROBENZENE REDUCTION BY IRON METAL. (R827117)

    EPA Science Inventory

    To evaluate the importance of external mass transport on the overall rates of
    contaminant reduction by iron metal (Fe0), we have compared measured
    rates of surface reaction for nitrobenzene (ArNO2) to estimated rates
    of external mass transport...

  17. Nanometer-scale properties of metal/oxide interfaces and ``end-on'' metal contacts to Si nanowires studied by ballistic electron emission microscopy (BEEM)

    NASA Astrophysics Data System (ADS)

    Pelz, Jon

    2012-02-01

    BEEM is a hot-electron (HE) technique based on scanning tunneling microscopy that can probe buried metal/semiconductor and metal/dielectric interfaces with nm-scale spatial resolution and energy resolution of a few meV. BEEM is a three-terminal technique, so the HE energy and interface electric field can be varied independently. I will discuss two studies of interest for future transistor technologies. The first concerns the band structure and alignments in a 20 nm-thick film of the high-k dielectric material Sc2O3 grown epitaxially on Si(111). Sc2O3 and related rare-earth/transition metal oxide films on Si were found to have similar band alignments and bandgap, and also ``tailing'' conduction band (CB) states extending ˜1 eV below the primary CB. We combined BEEM with internal photoemission to measure the band alignment and to study electron transport through these ``tail'' states.ootnotetextW. Cai, S. E. Stone, J. P. Pelz, L. F. Edge, and D. G. Schlom, Appl. Phys. Lett 91, 042901 (2007). Surprisingly, these tail states were found to form a robust band of extended states that supports elastic hot-electron transport even against an applied electric field. The second study concerns HE injection and transport through ``end-on'' metal contacts made to ˜100 nm diameter vertical Si nanowires (NWs) embedded in a SiO2 dielectric. At low HE flux, We observed lateral variations of the local Schottky Barrier Height (SBH) across individual end-on Au Schottky contacts, with the SBH at the contact edge found to be ˜25 meV lower than at the contact center. Finite-element electrostatic simulations suggest that this is due to a larger interface electric field at the contact edge due to positively charged Si/native-oxide interface states near the Au/NW contact, with this (equilibrium) interface state charge induced by local band bending due to the high work function Au contact. We also observed a strong suppression of the hot-electron transmission efficiency at larger HE flux

  18. Integrated mass transportation system study/definition/implementation program definition

    NASA Technical Reports Server (NTRS)

    Ransone, R. K.; Deptula, D. A.; Yorke, G. G.

    1975-01-01

    Specific actions needed to plan and effect transportation system improvements are identified within the constraints of limited financial, energy and land use resources, and diverse community requirements. A specific program is described which would develop the necessary generalized methodology for devising improved transportation systems and evaluate them against specific criteria for intermodal and intramodal optimization. A consistent, generalized method is provided for study and evaluation of transportation system improvements.

  19. Nanometer-scale characterization of laser-driven plasmas, compression, shocks and phase transitions, by coherent small angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Kluge, Thomas

    2015-11-01

    Combining ultra-intense short-pulse and high-energy long-pulse lasers, with brilliant coherent hard X-ray FELs, such as the Helmholtz International Beamline for Extreme Fields (HIBEF) under construction at the HED Instrument of European XFEL, or MEC at LCLS, holds the promise to revolutionize our understanding of many High Energy Density Physics phenomena. Examples include the relativistic electron generation, transport, and bulk plasma response, and ionization dynamics and heating in relativistic laser-matter interactions, or the dynamics of laser-driven shocks, quasi-isentropic compression, and the kinetics of phase transitions at high pressure. A particularly promising new technique is the use of coherent X-ray diffraction to characterize electron density correlations, and by resonant scattering to characterize the distribution of specific charge-state ions, either on the ultrafast time scale of the laser interaction, or associated with hydrodynamic motion. As well one can image slight density changes arising from phase transitions inside of shock-compressed high pressure matter. The feasibility of coherent diffraction techniques in laser-driven matter will be discussed. including recent results from demonstration experiments at MEC. Among other things, very sharp density changes from laser-driven compression are observed, having an effective step width of 10 nm or smaller. This compares to a resolution of several hundred nm achievedpreviously with phase contrast imaging. and on behalf of HIBEF User Consortium, for the Helmholtz International Beamline for Extreme Fields at the European XFEL.

  20. Imaging the time-integrated cerebral metabolic activity with subcellular resolution through nanometer-scale detection of biosynthetic products deriving from (13)C-glucose.

    PubMed

    Takado, Yuhei; Knott, Graham; Humbel, Bruno M; Masoodi, Mojgan; Escrig, Stéphane; Meibom, Anders; Comment, Arnaud

    2015-11-01

    Glucose is the primary source of energy for the brain but also an important source of building blocks for proteins, lipids, and nucleic acids. Little is known about the use of glucose for biosynthesis in tissues at the cellular level. We demonstrate that local cerebral metabolic activity can be mapped in mouse brain tissue by quantitatively imaging the biosynthetic products deriving from [U-(13)C]glucose metabolism using a combination of in situ electron microscopy and secondary ion mass-spectroscopy (NanoSIMS). Images of the (13)C-label incorporated into cerebral ultrastructure with ca. 100 nm resolution allowed us to determine the timescale on which the metabolic products of glucose are incorporated into different cells, their sub-compartments and organelles. These were mapped in astrocytes and neurons in the different layers of the motor cortex. We see evidence for high metabolic activity in neurons via the nucleus (13)C enrichment. We observe that in all the major cell compartments, such as e.g. nucleus and Golgi apparatus, neurons incorporate substantially higher concentrations of (13)C-label than astrocytes. PMID:26409162

  1. Upscaling transport with mass transfer models: Mean behavior and propagation of uncertainty

    NASA Astrophysics Data System (ADS)

    Fernã Ndez-Garcia, D.; Llerar-Meza, G.; Gómez-HernáNdez, J. Jaime

    2009-10-01

    The choice of an adequate large-scale conceptual transport model constitutes a major challenge associated with the upscaling of solute transport. Among the different alternatives to the classical advection-dispersion model, the (multirate) mass transfer model has been proposed as a valuable and convenient alternative to model the large-scale behavior of solute transport. This paper evaluates the use of mass transfer models as a constitutive equation for upscaling solute transport. To achieve this, we compare Monte Carlo simulations of solute transport at two different support scales. Transport simulations performed at the smallest scale represent a set of reference transport solutions described at a high resolution, which are contrasted against transport simulations obtained using an upscaled model (low resolution). Several formulations of the multirate mass transfer model, which differ in the type of memory function (single rate, double rate, and truncated power law), are used as a constitutive transport equation. The large-scale scenario represents a simplified model obtained by partially homogenizing the reference solution. Results show that the double-rate and the truncated power law mass transfer models are capable of properly describing the ensemble average behavior of the main features associated with the integrated breakthrough curves. However, the uncertainty associated with the upscaled mass transfer models was substantially smaller than that attributed to the reference solution. Importantly, the cumulative distribution function of concentrations associated with the upscaled model follows a distribution similar to the reference solution but with smaller statistical dispersion. The reason is that while appropriate memory functions can be used to preserve the residence time distribution of mass particles during upscaling, the lack of memory in space prevents the model from reproducing mass fluxes in all directions. Specifically, the reproduction of mass

  2. A boundary element-Random walk model of mass transport in groundwater

    USGS Publications Warehouse

    Kemblowski, M.

    1986-01-01

    A boundary element solution to the convective mass transport in groundwater is presented. This solution produces a continuous velocity field and reduces the amount of data preparation time and bookkeeping. By combining this solution and the random walk procedure, a convective-dispersive mass transport model is obtained. This model may be easily used to simulate groundwater contamination problems. The accuracy of the boundary element model has been verified by reproducing the analytical solution to a two-dimensional convective mass transport problem. The method was also used to simulate a convective-dispersive problem. ?? 1986.

  3. Degradation of (La0.6Sr0.4)0.95(Co0.2Fe0.8)O3-δ Solid Oxide Fuel Cell Cathodes at the Nanometer Scale and below.

    PubMed

    Ni, Na; Cooper, Samuel J; Williams, Robert; Kemen, Nils; McComb, David W; Skinner, Stephen J

    2016-07-13

    The degradation of intermediate temperature solid oxide fuel cell (ITSOFC) cathodes has been identified as a major issue limiting the development of ITSOFCs as high efficiency energy conversion devices. In this work, the effect of Cr poisoning on (La0.6Sr0.4)0.95(Co0.2Fe0.8)O3-δ (LSCF6428), a particularly promising ITSOFC cathode material, was investigated on symmetrical cells using electrochemical impedance spectroscopy and multiscale structural/chemical analysis by advanced electron and ion microscopy. The systematic combination of bulk and high-resolution analysis on the same cells allows, for the first time, direct correlation of Cr induced performance degradation with subtle and localized structural/chemical changes of the cathode down to the atomic scale. Up to 2 orders of magnitude reduction in conductivity, oxygen surface exchange rate, and diffusivity were observed in Cr poisoned LSCF6428 samples. These effects are associated with the formation of nanometer size SrCrO4; grain boundary segregation of Cr; enhanced B-site element exsolution (both Fe and Co); and reduction in the Fe valence, the latter two being related to Cr substitution in LSCF. The finding that significant degradation of the cathode happens before obvious microscale change points to new critical SOFC degradation mechanisms effective at the nanometer scale and below. PMID:27336290

  4. Simultaneous depth-resolved imaging of sub-nanometer scale ossicular vibrations and morphological features of the human-cadaver middle ear with spectral-domain phase-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Subhash, Hrebesh M.; Nguyen-Huynh, Anh; Wang, Ruikang K.; Jacques, Steven L.; Nuttall, Alfred L.

    2012-02-01

    We describe a novel method for the detection of the tiny motions of the middle ear (ME) ossicles and their morphological features with a spectral-domain phase sensitive optical coherence tomography (PS-OCT). Laser Doppler Vibrometry (LDV) and its variations are the most extensively used methods for studding the vibrational modes of the ME. However, most techniques are limited to single point analysis methods, and do not have the ability to provide depth resolved simultaneous imaging of multiple points on the ossicles especially with the intact eardrum. Consequently, the methods have the limited ability to provide relative vibration information at these points. In this study, we demonstrated the feasibility of using PS-OCT for simultaneous depth resolved imaging of both vibration information and morphological features in a cadaver human middle ear with high sensitivity and resolution. This technique has the potential to provide meaningful vibration of ossicles with a vibration sensitivity of ~0.5nm at 1kHz acoustic stimulation. To the best of our knowledge, this is the first demonstration of depth-resolved vibration imaging of ossicles with a PS-OCT system at sub-nanometer scale.

  5. Subcontinuum mass transport of condensed hydrocarbons in nanoporous media

    NASA Astrophysics Data System (ADS)

    Falk, Kerstin; Coasne, Benoit; Pellenq, Roland; Ulm, Franz-Josef; Bocquet, Lydéric

    2015-04-01

    Although hydrocarbon production from unconventional reservoirs, the so-called shale gas, has exploded recently, reliable predictions of resource availability and extraction are missing because conventional tools fail to account for their ultra-low permeability and complexity. Here, we use molecular simulation and statistical mechanics to show that continuum description--Darcy's law--fails to predict transport in shales nanoporous matrix (kerogen). The non-Darcy behaviour arises from strong adsorption in kerogen and the breakdown of hydrodynamics at the nanoscale, which contradict the assumption of viscous flow. Despite this complexity, all permeances collapse on a master curve with an unexpected dependence on alkane length. We rationalize this non-hydrodynamic behaviour using a molecular description capturing the scaling of permeance with alkane length and density. These results, which stress the need for a change of paradigm from classical descriptions to nanofluidic transport, have implications for shale gas but more generally for transport in nanoporous media.

  6. Subcontinuum mass transport of condensed hydrocarbons in nanoporous media

    PubMed Central

    Falk, Kerstin; Coasne, Benoit; Pellenq, Roland; Ulm, Franz-Josef; Bocquet, Lydéric

    2015-01-01

    Although hydrocarbon production from unconventional reservoirs, the so-called shale gas, has exploded recently, reliable predictions of resource availability and extraction are missing because conventional tools fail to account for their ultra-low permeability and complexity. Here, we use molecular simulation and statistical mechanics to show that continuum description—Darcy's law—fails to predict transport in shales nanoporous matrix (kerogen). The non-Darcy behaviour arises from strong adsorption in kerogen and the breakdown of hydrodynamics at the nanoscale, which contradict the assumption of viscous flow. Despite this complexity, all permeances collapse on a master curve with an unexpected dependence on alkane length. We rationalize this non-hydrodynamic behaviour using a molecular description capturing the scaling of permeance with alkane length and density. These results, which stress the need for a change of paradigm from classical descriptions to nanofluidic transport, have implications for shale gas but more generally for transport in nanoporous media. PMID:25901931

  7. Subcontinuum mass transport of condensed hydrocarbons in nanoporous media.

    PubMed

    Falk, Kerstin; Coasne, Benoit; Pellenq, Roland; Ulm, Franz-Josef; Bocquet, Lydéric

    2015-01-01

    Although hydrocarbon production from unconventional reservoirs, the so-called shale gas, has exploded recently, reliable predictions of resource availability and extraction are missing because conventional tools fail to account for their ultra-low permeability and complexity. Here, we use molecular simulation and statistical mechanics to show that continuum description--Darcy's law--fails to predict transport in shales nanoporous matrix (kerogen). The non-Darcy behaviour arises from strong adsorption in kerogen and the breakdown of hydrodynamics at the nanoscale, which contradict the assumption of viscous flow. Despite this complexity, all permeances collapse on a master curve with an unexpected dependence on alkane length. We rationalize this non-hydrodynamic behaviour using a molecular description capturing the scaling of permeance with alkane length and density. These results, which stress the need for a change of paradigm from classical descriptions to nanofluidic transport, have implications for shale gas but more generally for transport in nanoporous media. PMID:25901931

  8. Measurements of the transport efficiency of the fragment mass analyzer

    SciTech Connect

    Back, B.B.; Blumenthal, D.J.; Davids, C.N.

    1995-08-01

    Extensive calculations of the transport of reaction products were carried out during the design phase of the instrument using the computer code GIOS. These show that the energy acceptance depends strongly on the angular deviation from the optical axis of the instrument. In order to reliably measure cross sections using this instrument it is therefore necessary to verify these calculations empirically.

  9. Cable Connected Spinning Spacecraft, 1. the Canonical Equations, 2. Urban Mass Transportation, 3

    NASA Technical Reports Server (NTRS)

    Sitchin, A.

    1972-01-01

    Work on the dynamics of cable-connected spinning spacecraft was completed by formulating the equations of motion by both the canonical equations and Lagrange's equations and programming them for numerical solution on a digital computer. These energy-based formulations will permit future addition of the effect of cable mass. Comparative runs indicate that the canonical formulation requires less computer time. Available literature on urban mass transportation was surveyed. Areas of the private rapid transit concept of urban transportation are also studied.

  10. Mass transport in salt repositories: Steady-state transport through interbeds

    SciTech Connect

    Hwang, Y.; Lee, W.W.-L.; Chambre, P.L.; Pigford, T.H. . Dept. of Nuclear Engineering)

    1989-03-01

    Salt has long been a candidate for geologic disposal of nuclear waste. Because salt is extremely soluble in water, the existence of rock salt in the ground atest to the long-term stability of the salt. Both bedded salt and salt domes have been considered for nuclear waste disposal in the United States and Europe. While the salt is known to be quite pure in salt domes, bedded salt is interlaced with beds of sediments. Traditionally rock salt has not been considered water-conducting, but sediments layers would be classical porous media, capable of conducting water. Therefore there is interest in determining whether interbeds in bedded salt constitute pathway for radionuclide migration. In this report we consider steady-state migration of radionuclides from a single waste cylinder into a single interbed. Two approaches are used. In 1982 Neretnieks proposed an approach for calculating the steady-state transport of oxidants to a copper container. We have adapted that approach for calculating steady-state radionuclide migration away from the waste package, as a first approximation. We have also analyzed the problem of time-dependent radionuclide diffusion from a container through a backfill layer into a fracture, and we used the steady-state solution from that problem for comparison. Section 2 gives a brief summary of the geology of interbeds in bedded salt. Section 3 presents the mass transfer resistances approach of Neretnieks, summarizing the formulation and giving numerical illustrations of the steady-state two-dimensional diffusion analysis. Section 4 gives a brief statement of the steady-state result from a related analysis. Conclusions are stated in Section 5. 13 refs., 5 figs., 2 tabs.

  11. Structural design of a double-layered porous hydrogel for effective mass transport

    PubMed Central

    Kim, Hyejeong; Kim, Hyeon Jeong; Huh, Hyung Kyu; Hwang, Hyung Ju; Lee, Sang Joon

    2015-01-01

    Mass transport in porous materials is universal in nature, and its worth attracts great attention in many engineering applications. Plant leaves, which work as natural hydraulic pumps for water uptake, have evolved to have the morphological structure for fast water transport to compensate large water loss by leaf transpiration. In this study, we tried to deduce the advantageous structural features of plant leaves for practical applications. Inspired by the tissue organization of the hydraulic pathways in plant leaves, analogous double-layered porous models were fabricated using agarose hydrogel. Solute transport through the hydrogel models with different thickness ratios of the two layers was experimentally observed. In addition, numerical simulation and theoretical analysis were carried out with varying porosity and thickness ratio to investigate the effect of structural factors on mass transport ability. A simple parametric study was also conducted to examine unveiled relations between structural factors. As a result, the porosity and thickness ratio of the two layers are found to govern the mass transport ability in double-layered porous materials. The hydrogel models with widely dispersed pores at a fixed porosity, i.e., close to a homogeneously porous structure, are mostly turned out to exhibit fast mass transport. The present results would provide a new framework for fundamental design of various porous structures for effective mass transport. PMID:25825619

  12. Surface chemistry at the nanometer scale

    NASA Astrophysics Data System (ADS)

    Cao, Peigen

    This thesis describes research towards understanding surface chemical and physical processes, as well as their effects on the underlying substrate properties, at the nanometer and atomic scales. We demonstrate a method to tune the density of etch pits on Si(111) during the chlorination process so as to change the surface reactivity. Subsequent grafting of an azide group to replace chlorine demonstrates an example of non-oxidative passivation of silicon surfaces with new functionalities. Depending upon the solvent used in the azidation process, it is shown to yield different azidation kinetic rates, different final azide coverages, and different surface-area distributions. Scanning tunneling spectroscopy studies show that both chlorination and azidation processes significantly modify the surface electronic structures, with the former leading to a non-zero density of states at the Fermi level. Our studies on a new class of corrugation, i.e., wrinkles, in exfoliated graphene on SiO2 show that a "three-for-six" triangular pattern of atoms is exclusively and consistently observed on wrinkles, suggesting the local curvature of the wrinkle is a perturbation that breaks the six-fold symmetry of the graphene lattice. Lower electrical conductance is also found on the top of wrinkles compared to other regions of graphene. The wrinkles are characterized by the presence of midgap states, which is in agreement with recent theoretical predictions. A general method is also reported for reliably fabricating ultrahigh-density graphene nanoribbon (GNR) arrays. We have clearly observed how the properties of GNRs evolve as a function of number of graphene layers. The band gap (and so the on-off ratio) decreases as the number of layers increases. These results suggest that, in addition to single layer graphene, properties of GNRs of different thicknesses can also be harnessed for engineering GNRs as different building blocks towards FET applications. A novel imaging technique, graphene-templated scanning probe microscopy, has been developed and applied for the study on the condensation process of water and small organic molecules on mica. We found that these molecular adlayers grow epitaxially on the mica substrate in a layer-by-layer fashion. In particular, submonolayers of water form atomically flat, faceted islands of height 0.37 plus or minus 0.02 nm, in agreement with the height of a monolayer of ice. The second adlayers also appear ice-like, and thicker layers appear liquid-like. This general mechanism, however, is not universal. Exclusively three-dimensional droplets of water are observed on chemically modified (hydrophobic) mica surfaces, suggesting a 3D growth mechanism. This thesis also includes my work on the design of a quartz-tuning-fork-based force sensor and related electronics for applications on low-temperature atomic force microscopy. Results show that the force-sensor-global-feedback circuit detector system induced lowest noise floor. The high detection sensitivity of this system demonstrates its ability to be used in frequency-modulated AFM at cryogenic temperatures. Surface topographic imaging of H-terminated Si(111) has been achieved at low temperatures.

  13. Thermoelectric device with multiple, nanometer scale, elements

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre (Inventor); Ryan, Margaret A. (Inventor); Borshchevsky, Alexander (Inventor); Herman, Jennifer (Inventor)

    2006-01-01

    A thermoelectric device formed of nanowires on the nm scale. The nanowires are preferably of a size that causes quantum confinement effects within the wires. The wires are connected together into a bundle to increase the power density.

  14. Jumping, snapping and popping at nanometer scale

    NASA Astrophysics Data System (ADS)

    Haviland, David

    2015-03-01

    The 'jump-to-contact' instability is well known in Atomic Force Microscopy. When a tip attached to a soft cantilever approaches a surface, the large attractive force gradient disrupts the quasi-static force balance and the tip snaps in to contact with the surface. Less appreciated is the converse instability, where a soft liquid-like polymer surface jumps to meet the tip. This nano-scale pop is inaudible, but it does leave a distinctive signature if one carefully monitors the cantilever's steady state dynamics when driven with multiple tones. The nonlinear tip-surface interaction causes intermodulation, or frequency mixing of the drive tones. When many intermodulation products are measured close to the cantilever resonance the spectrum can be transformed to reveal the in-phase and quadrature forces acting on the tip, as a function of oscillation amplitude. We present experimental measurements and theoretical modelling that reveal this surface-jump-to-tip instability.

  15. Polarization-multiplexed encoding at nanometer scales.

    PubMed

    Macias-Romero, C; Munro, P R T; Török, P

    2014-10-20

    Optical data storage was developed using binary encoding primarily due to signal to noise ratio considerations. We report on a multiplexing method that allows a seven fold storage increase, per storage layer, per side, and propose one that can yield theoretically a 20+ fold increase. Multiplexing is achieved by encoding information in polarization via appropriately oriented nanostructures that emit strongly polarized light when excited by unpolarized light. The storage increase is possible due to the significantly reduced crosstalk that results form using unpolarized light. PMID:25401656

  16. Dynamics of heat and mass transport in a quantum insulator

    NASA Astrophysics Data System (ADS)

    Łącki, Mateusz; Delande, Dominique; Zakrzewski, Jakub

    2015-04-01

    The real-time evolution of two pieces of quantum insulators, initially at different temperatures, is studied when they are glued together. Specifically, each subsystem is taken as a Bose-Hubbard model in a Mott insulator state. The process of temperature equilibration via heat transfer is simulated in real time using the minimally entangled typical thermal states algorithm. The analytic theory based on quasiparticle transport is also given.

  17. Mass spectrometer. [On Space Transportation System 2 Flight

    NASA Technical Reports Server (NTRS)

    Miller, E. R.; Carignan, G. R.

    1983-01-01

    The quadrupole Mass Spectrometer of the Induced Environment Contamination Monitor (IECM) operates in the range from 2 to 150 amu. It is pointed out that the Mass Spectrometer on STS-2 performed very well. It was found that the column density of H2O effluent from the Shuttle reached a maximum of 1 x 10 to the 13th per sq cm at 7 hr, 30 min and decreased by a factor of 7.5 during the subsequent 40 hrs. The count rate response of H2O could be correlated with mission-related events, taking into account the dumping of supply water, the operation of the Flash Evaporator System, and the firing of a primary reaction control system engine.

  18. Measurement and Visualization of Mass Transport for the Flowing Atmospheric Pressure Afterglow (FAPA) Ambient Mass-Spectrometry Source

    PubMed Central

    Pfeuffer, Kevin P.; Ray, Steven J.; Hieftje, Gary M.

    2014-01-01

    Ambient desorption/ionization mass spectrometry (ADI-MS) has developed into an important analytical field over the last nine years. The ability to analyze samples under ambient conditions while retaining the sensitivity and specificity of mass spectrometry has led to numerous applications and a corresponding jump in the popularity of this field. Despite the great potential of ADI-MS, problems remain in the areas of ion identification and quantification. Difficulties with ion identification can be solved through modified instrumentation, including accurate-mass or MS/MS capabilities for analyte identification. More difficult problems include quantification due to the ambient nature of the sampling process. To characterize and improve sample volatilization, ionization, and introduction into the mass-spectrometer interface, a method of visualizing mass transport into the mass spectrometer is needed. Schlieren imaging is a well-established technique that renders small changes in refractive index visible. Here, schlieren imaging was used to visualize helium flow from a plasma-based ADI-MS source into a mass spectrometer while ion signals were recorded. Optimal sample positions for melting-point capillary and transmission-mode (stainless steel mesh) introduction were found to be near (within 1 mm of) the mass spectrometer inlet. Additionally, the orientation of the sampled surface plays a significant role. More efficient mass transport resulted for analyte deposits directly facing the MS inlet. Different surfaces (glass slide and rough surface) were also examined; for both it was found that the optimal position is immediately beneath the MS inlet. PMID:24658804

  19. Modeling of diagenesis in relation to coupled mass and heat transport

    SciTech Connect

    Ondrak, R.

    1996-12-31

    Pore fluid flow is an important factor influencing the diagenetic evolution of rocks, as has been shown by various diagenetic studies, especially in connection with fluid inclusion measurements. A 3D- computer model is presented, which allows to simulate coupled mass and heat transport in porous rocks. The model is used to study the interaction of heat and mass transport with respect to the temporal and spatial evolution of sandstones. Mineral dissolution or precipitation change the mineralogical composition of rocks, and modify the physical properties at the same time. Altering the permeability of the rock affects the fluid flow system in the rock which determines the mass transport of the entire system. In addition to mass transport, fluid flow transports thermal energy, which may modify the temperature evolution of the rock. The model will be used to examine the effect of convective heat and mass transport on temperature and diagenetic evolution of clastic rocks. Although the model cannot claim to simulate nature, it can be used to study the effect of different mechanisms, and their interaction within the coupled system. For practical applications, the model may be used to determine possible flow rates, which are necessary to explain the observed diagenetic and thermal history of sandstones.

  20. Spatial correlations, additivity, and fluctuations in conserved-mass transport processes

    NASA Astrophysics Data System (ADS)

    Das, Arghya; Chatterjee, Sayani; Pradhan, Punyabrata

    2016-06-01

    We exactly calculate two-point spatial correlation functions in steady state in a broad class of conserved-mass transport processes, which are governed by chipping, diffusion, and coalescence of masses. We find that the spatial correlations are in general short-ranged and, consequently, on a large scale, these transport processes possess a remarkable thermodynamic structure in the steady state. That is, the processes have an equilibrium-like additivity property and, consequently, a fluctuation-response relation, which help us to obtain subsystem mass distributions in the limit of subsystem size large.

  1. On the optimum fields and bounds for heat and mass transport in two turbulent flows

    NASA Astrophysics Data System (ADS)

    Vitanov, Nikolay

    2011-12-01

    The optimum theory of turbulence is one of the few tools for obtaining analytical results for transport of heat, mass or momentum by turbulent flows. This is achieved by asymptotic theory which is valid for large values of the characteristic numbers of the investigated fluid system. For small and intermediate values of the Reynolds, Rayleigh or Taylor numbers we have to solve numerically the Euler-Lagrange equations of the corresponding variational problems. Below we discuss numerical results from the application of the Howard-Busse method of the optimum theory of turbulence to two problems: convective heat transport in non-rotating and rotating fluid layer and mass transport in pipe flow. We obtain profiles of the optimum fields and discuss the evolution of the thickness of the boundary layers as well as present our first results about the lower bound on the mass transport in a pipe flow.

  2. A Global Assessment of Accelerations in Mass Transport of Surface Geophysical Fluid

    NASA Astrophysics Data System (ADS)

    Wu, X.; Heflin, M. B.

    2015-12-01

    Mass transport in the Earth's surface geophysical fluid layer has complex spatiotemporal patterns. The GRACE gravity mission provides an unprecedented global capability to monitor this important process with high accuracy and resolution. Accurate assessments of global mass transport patterns and budget also depend critically on changes in degree-1 coefficients (geocenter motion) and in Earth's dynamic oblateness coefficient J2. We combine GRACE measurements, time series of GNSS data, JPL's ECCO ocean bottom pressure model, and high-resolution loose a priori models of mass variation regimes to derive complete spherical harmonic spectra of detrended mass variations up to degree and order 180. Mass accelerations are estimated along with linear, annual, semiannual, and the 161-day tidal aliasing components from coefficient time series. The appropriateness of a priori information and estimate uncertainties are further evaluated by variance component estimation and residual statistics of fitting the time series. During the GRACE data period of 2002.2-2015.0, accelerations in mass transport are geographically uneven with significant positive or negative accelerations in various parts of the world. While Greenland and West Antarctica show strong accelerated mass losses, Alaska and the Arctic Ocean have significant positive accelerations with reversals of earlier mass loss trends. No evidence of non-Arctic global mean sea level acceleration due to mass has been found. Depending on region, some estimated accelerations are also not steady over time due to large irregular and interannual variations.

  3. Transport of magnetic flux and mass in Saturn's inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Lai, H. R.; Russell, C. T.; Jia, Y. D.; Wei, H. Y.; Dougherty, M. K.

    2016-04-01

    It is well accepted that cold plasma sourced by Enceladus is ultimately lost to the solar wind, while the magnetic flux convecting outward with the plasma must return to the inner magnetosphere. However, whether the interchange or reconnection, or a combination of the two processes is the dominant mechanism in returning the magnetic flux is still under debate. Initial Cassini observations have shown that the magnetic flux returns in the form of flux tubes in the inner magnetosphere. Here we investigate those events with 10 year Cassini magnetometer data and confirm that their magnetic signatures are determined by the background plasma environments: inside (outside) the plasma disk, the returning magnetic field is enhanced (depressed) in strength. The distribution, temporal variation, shape, and transportation rate of the flux tubes are also characterized. The flux tubes break into smaller ones as they convect in. The shape of their cross section is closer to circular than fingerlike as produced in the simulations based on the interchange mechanism. In addition, no sudden changes in any flux tube properties can be found at the "boundary" which has been claimed to separate the reconnection and interchange-dominant regions. On the other hand, reasonable cold plasma loss rate and outflow velocity can be obtained if the transport rate of the magnetic flux matches the reconnection rate, which supports reconnection alone as the dominant mechanism in unloading the cold plasma from the inner magnetosphere and returning the magnetic flux from the tail.

  4. Nanometer-scale separation of d(10) Zn(2+)-layers and twin-shift competition in Ba8ZnNb6O24-based 8-layered hexagonal perovskites.

    PubMed

    Lu, Fengqi; Wang, Xiaoming; Pan, Zhengwei; Pan, Fengjuan; Chai, Shiqiang; Liang, Chaolun; Wang, Quanchao; Wang, Jing; Fang, Liang; Kuang, Xiaojun; Jing, Xiping

    2015-08-01

    The 8-layered shifted hexagonal perovskite compound Ba8ZnNb6O24 was isolated via controlling the ZnO volatilization, which features long-range B-cation ordering with nanometer-scale separation by ∼1.9 nm of octahedral d(10) cationic (Zn(2+)) layers within the purely corner-sharing octahedral d(0) cationic (Nb(5+)) host. The long-range ordering of the B-site vacancy and out-of-center distortion of the highly-charged d(0) Nb(5+) that is assisted by the second-order Jahn-Teller effect contribute to this unusual B-cation ordering in Ba8ZnNb6O24. A small amount (∼15%) of d(10) Sb(5+) substitution for Nb(5+) in Ba8ZnNb6-xSbxO24 dramatically transformed the shifted structure to a twinned structure, in contrast with the Ba8ZnNb6-xTaxO24 case requiring 50% d(0) Ta(5+) substitution for Nb(5+) for such a shift-to-twin transformation. Multiple factors including B-cationic sizes, electrostatic repulsion forces, long-range ordering of B-site vacancies, and bonding preferences arising from a covalent contribution to the B-O bonding that includes out-of-center octahedral distortion and the B-O-B bonding angle could subtly contribute to the twin-shift phase competition of B-site deficient 8-layered hexagonal perovskites Ba8B7O24. The ceramics of new shifted Ba8ZnNb6O24 and twinned Ba8ZnNb5.1Sb0.9O24 compounds exhibited good microwave dielectric properties (εr ∼ 35, Qf ∼ 36 200-43 400 GHz and τf ∼ 38-44 ppm/°C). PMID:26110444

  5. Local pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit pore obtained by the perturbative method

    SciTech Connect

    Fujiwara, K.; Shibahara, M.

    2015-03-07

    A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal local thermodynamic states: local pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the local thermodynamic quantities from a molecular point of view. An instantaneous expression of the local pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the local pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative method. The results revealed that the local pressure components tangential to the solid surface in the vicinity of the 1st fluid layer from the solid surface are different in a two dimensional plane, and the difference became pronounced in the vicinity of the corner of the slit, for cases where the fluid-solid interaction intensities are relatively strong. The results for the local interfacial tensions of the fluid inside the slit suggested that the local interfacial tensions in the vicinity of the 2nd and 3rd layers of the solid atoms from the entrance of the slit act as a trigger for the transition between the two states under the influence of a varying fluid-solid interaction.

  6. Heat- and mass-transport in aqueous silica nanofluids

    NASA Astrophysics Data System (ADS)

    Turanov, A. N.; Tolmachev, Yuriy V.

    2009-10-01

    Using the transient hot wire and pulsed field gradient nuclear magnetic resonance methods we determined the thermal conductivity and the solvent self-diffusion coefficient (SDC) in aqueous suspensions of quasi-monodisperse spherical silica nanoparticles. The thermal conductivity was found to increase at higher volume fraction of nanoparticles in accordance with the effective medium theory albeit with a smaller slope. On the other hand, the SDC was found to decrease with nanoparticle volume fraction faster than predicted by the effective medium theory. These deviations can be explained by the presence of an interfacial heat-transfer resistance and water retention by the nanoparticles, respectively. We found no evidence for anomalous enhancement in the transport properties of nanofluids reported earlier by other groups.

  7. Mass-height profile and total mass transport of wind eroded aeolian sediments from rangelands of the Indian Thar Desert

    NASA Astrophysics Data System (ADS)

    Mertia, R. S.; Santra, Priyabrata; Kandpal, B. K.; Prasad, R.

    2010-11-01

    Wind erosion is an active land degradation process in the Indian Thar Desert and severe dust storm events during hot summer months in the region are very common. Assessment of soil loss due to dust storm events from major land use systems of the Indian Thar Desert is highly essential for proper environmental planning. Characterization of the mass-height profile of wind eroded aeolian sediment is an important step to compute soil loss/mass transport but was not previously studied in the region. In the present study, aeolian mass fluxes (kg m -2) at different heights from soil surface were measured at two major rangelands in the Indian Thar Desert: Overgrazing rangeland at Jaisalmer (26°55'N and 70°57'E), and controlled grazing rangeland at Chandan (27°01'N and 71°01'E). Evaluation of several mass-height profile models revealed that a power decay function [ q( z) = az-b, where q( z) is the measured mass flux at an height of z (m) from soil surface; a and b are parameters of the equation] was best to characterize the mass-height relationship of aeolian sediments from the Indian Thar Desert. The average mass transport rate (kg m -1 day -1) or the total soil loss during hot summer months was significantly higher at the overgrazed rangeland site than at the controlled grazing rangeland site. Therefore, protection of existing rangelands, which comprise about 80% geographical area of the Indian Thar Desert may check the land degradation process due to wind erosion.

  8. Mass Transport in Nanocomposite Materials for Membrane Separations

    NASA Astrophysics Data System (ADS)

    Galizia, Michele; Puccini, Ilaria; Messori, Massimo; Grazia De Angelis, Maria; Sarti, Giulio C.

    2010-06-01

    The vapor transport properties of nanocomposite materials obtained with different techniques and based on a high free volume glassy polymer suitable for membrane separations, poly[1-(trimethylsilyl)-1-propyne] (PTMSP), have been determined and modeled. The simple mixing in solution of hydrophobic fumed silica nanoparticles with PTMSP leads to mixed matrix membranes, which show higher free volume and higher values of diffusivity and permeability than the pure polymeric material. If a sol-gel route is followed, with PTMSP and Tetraethoxysylane (TEOS) as precursor of the silica phase, one obtains hybrid matrices characterized by lower vapor diffusion and sorption values with respect to the pure polymer. Although the trends observed are very regular functions of the silica content in the composite, none of the behavior observed obeys traditional models for composites permeability, such as the Maxwell's one. Both types of behaviors were modeled considering the variation of polymer fractional free volume induced by the inorganic phase: in the mixed matrices the poor interactions between silica and polymer chains favor the formation of nanovoids at the interface, increasing the free volume and the vapor diffusivity, while in the more interconnected hybrid matrices the inorganic domains act as constraints, reducing the volume occupied by the polymeric phase, which is naturally endowed with a very high excess free volume.

  9. Modification of the finite element heat and mass transfer code (FEHMN) to model multicomponent reactive transport

    SciTech Connect

    Viswanathan, H.S.

    1995-12-31

    The finite element code FEHMN is a three-dimensional finite element heat and mass transport simulator that can handle complex stratigraphy and nonlinear processes such as vadose zone flow, heat flow and solute transport. Scientists at LANL have been developed hydrologic flow and transport models of the Yucca Mountain site using FEHMN. Previous FEHMN simulations have used an equivalent K{sub d} model to model solute transport. In this thesis, FEHMN is modified making it possible to simulate the transport of a species with a rigorous chemical model. Including the rigorous chemical equations into FEHMN simulations should provide for more representative transport models for highly reactive chemical species. A fully kinetic formulation is chosen for the FEHMN reactive transport model. Several methods are available to computationally implement a fully kinetic formulation. Different numerical algorithms are investigated in order to optimize computational efficiency and memory requirements of the reactive transport model. The best algorithm of those investigated is then incorporated into FEHMN. The algorithm chosen requires for the user to place strongly coupled species into groups which are then solved for simultaneously using FEHMN. The complete reactive transport model is verified over a wide variety of problems and is shown to be working properly. The simulations demonstrate that gas flow and carbonate chemistry can significantly affect {sup 14}C transport at Yucca Mountain. The simulations also provide that the new capabilities of FEHMN can be used to refine and buttress already existing Yucca Mountain radionuclide transport studies.

  10. Fram Strait and Greenland Sea transports, water masses, and water mass transformations 1999-2010 (and beyond)

    NASA Astrophysics Data System (ADS)

    Marnela, Marika; Rudels, Bert; Goszczko, Ilona; Beszczynska-Möller, Agnieszka; Schauer, Ursula

    2016-04-01

    The exchanges between the Nordic Seas and the Arctic Ocean are important for the ocean circulation and climate. Transports are here estimated using summer hydrographic data from the Greenland Sea and the Fram Strait. Geostrophic transports are computed from hydrographic sections at 75°N in the Greenland Sea and at about 79°N in the Fram Strait. Geostrophic velocities are adjusted with summer velocities derived from Argo floats, and four conservation constraints are applied to a box closed by the two sections. The estimated net volume transports are 0.8 ± 1.5 Sv southward. Net freshwater transports through the Greenland Sea section are estimated at 54 ± 20 mSv and through the Fram Strait section at 66 ± 9 mSv. Heat loss in the area between the two sections is estimated at 9 ± 12 TW. Convection depths in the Greenland Sea are estimated from observations and vary between about 200 and 2000 dbar showing no trend. Water mass properties in the Greenland Sea are affected both by convection and lateral mixing. Vertical mixing is estimated from hydrography and based on it about 1 Sv of diluted Arctic Ocean waters are estimated to enter the Greenland Sea. The properties of Atlantic, intermediate, and deep waters are studied. Deep water properties are defined using water mass triangles and are subject to decadal changes.

  11. Temporal variability of mass transport across Canary Islands Channels

    NASA Astrophysics Data System (ADS)

    Marrero-Díaz, Ángeles; Rodríguez-Santana, Ángel; José Machín, Francisco; García-Weil, Luis; Sangrà, Pablo; Vélez-Belchí, Pedro; Fraile-Nuez, Eugenio

    2014-05-01

    The equatorward flowing Canary Current (CC) is the main feature of the circulation in the Canary Islands region. The CC flow perturbation by the Canary Islands originate the Canary Eddy Corridor which is the major pathway for long lived eddies in the subtropical North Atlantic (Sangrà et al., 2009, DSR). Therefore the variability of the CC passing through the Canary Archipelago will have both local and regional importance. Past studies on the CC variability trough the Canary Islands point out a clearly seasonal variability (Fraile-Nuez et al, 2010 (JGR); Hernández-Guerra et al, 2002 (DSR)). However those studies where focused on the eastern islands channels missing the variability through the western island channels which are the main source of long lived eddies. In order to fill this gap from November 2012 until September 2013 we conducted trimonthly surveys crossing the whole islands channels using opportunity ships (Naviera Armas Ferries). XBT and XCTD where launched along the cross channels transects. Additionally a closed box circling the Archipelago was performed on October 2013 as part of the cruise RAPROCAN-2013 (IEO) using also XBT and XCTD. Dynamical variables where derived inferring salinity from S(T,p) analytical relationships for the region updated with new XCTD data. High resolution, vertical sections of temperature, potential density, geostrophic velocity and transport where obtained. Our preliminary results suggest that the CC suffer a noticeable acceleration in those islands channels where eddy shedding is more frequent. They also indicate a clearly seasonal variability of the flows passing the islands channels. With this regard we observed significant differences on the obtained seasonal variability with respect the cited past studies on the eastern islands channel (Lanzarote / Fuerteventura - Africa coast). This work was co-funded by Canary Government (TRAMIC project: PROID20100092) and the European Union (FEDER).

  12. Mass transport at infinite regular arrays of microband electrodes submitted to natural convection: theory and experiments.

    PubMed

    Pebay, Cécile; Sella, Catherine; Thouin, Laurent; Amatore, Christian

    2013-12-17

    Mass transport at infinite regular arrays of microband electrodes was investigated theoretically and experimentally in unstirred solutions. Even in the absence of forced hydrodynamics, natural convection limits the convection-free domain up to which diffusion layers may expand. Hence, several regimes of mass transport may take place according to the electrode size, gap between electrodes, time scale of the experiment, and amplitude of natural convection. They were identified through simulation by establishing zone diagrams that allowed all relative contributions to mass transport to be delineated. Dynamic and steady-state regimes were compared to those achieved at single microband electrodes. These results were validated experimentally by monitoring the chronoamperometric responses of arrays with different ratios of electrode width to gap distance and by mapping steady-state concentration profiles above their surface through scanning electrochemical microscopy. PMID:24283775

  13. A PERFECT MATCH CONDITION FOR POINT-SET MATCHING PROBLEMS USING THE OPTIMAL MASS TRANSPORT APPROACH

    PubMed Central

    CHEN, PENGWEN; LIN, CHING-LONG; CHERN, I-LIANG

    2013-01-01

    We study the performance of optimal mass transport-based methods applied to point-set matching problems. The present study, which is based on the L2 mass transport cost, states that perfect matches always occur when the product of the point-set cardinality and the norm of the curl of the non-rigid deformation field does not exceed some constant. This analytic result is justified by a numerical study of matching two sets of pulmonary vascular tree branch points whose displacement is caused by the lung volume changes in the same human subject. The nearly perfect match performance verifies the effectiveness of this mass transport-based approach. PMID:23687536

  14. Recent Developments in Graphene-Based Membranes: Structure, Mass-Transport Mechanism and Potential Applications.

    PubMed

    Sun, Pengzhan; Wang, Kunlin; Zhu, Hongwei

    2016-03-01

    Significant achievements have been made on the development of next-generation filtration and separation membranes using graphene materials, as graphene-based membranes can afford numerous novel mass-transport properties that are not possible in state-of-art commercial membranes, making them promising in areas such as membrane separation, water desalination, proton conductors, energy storage and conversion, etc. The latest developments on understanding mass transport through graphene-based membranes, including perfect graphene lattice, nanoporous graphene and graphene oxide membranes are reviewed here in relation to their potential applications. A summary and outlook is further provided on the opportunities and challenges in this arising field. The aspects discussed may enable researchers to better understand the mass-transport mechanism and to optimize the synthesis of graphene-based membranes toward large-scale production for a wide range of applications. PMID:26797529

  15. Concentration and mass dependence of transport coefficients and correlation functions in binary mixtures with high mass asymmetry.

    PubMed

    Fenz, W; Mryglod, I M; Prytula, O; Folk, R

    2009-08-01

    Correlation functions and transport coefficients of self-diffusion and shear viscosity of a binary Lennard-Jones mixture with components differing only in their particle mass are studied up to high values of the mass ratio mu, including the limiting case mu = infinity, for different mole fractions x. Within a large range of x and mu the product of the diffusion coefficient of the heavy species D(2) and the total shear viscosity of the mixture eta(m) is found to remain constant, obeying a generalized Stokes-Einstein relation. At high liquid density, large mass ratios lead to a pronounced cage effect that is observable in the mean square displacement, the velocity autocorrelation function, and the van Hove correlation function. PMID:19792112

  16. Concentration and mass dependence of transport coefficients and correlation functions in binary mixtures with high mass asymmetry

    NASA Astrophysics Data System (ADS)

    Fenz, W.; Mryglod, I. M.; Prytula, O.; Folk, R.

    2009-08-01

    Correlation functions and transport coefficients of self-diffusion and shear viscosity of a binary Lennard-Jones mixture with components differing only in their particle mass are studied up to high values of the mass ratio μ , including the limiting case μ=∞ , for different mole fractions x . Within a large range of x and μ the product of the diffusion coefficient of the heavy species D2 and the total shear viscosity of the mixture ηm is found to remain constant, obeying a generalized Stokes-Einstein relation. At high liquid density, large mass ratios lead to a pronounced cage effect that is observable in the mean square displacement, the velocity autocorrelation function, and the van Hove correlation function.

  17. Intra-tumoral heterogeneity of gemcitabine delivery and mass transport in human pancreatic cancer.

    PubMed

    Koay, Eugene J; Baio, Flavio E; Ondari, Alexander; Truty, Mark J; Cristini, Vittorio; Thomas, Ryan M; Chen, Rong; Chatterjee, Deyali; Kang, Ya'an; Zhang, Joy; Court, Laurence; Bhosale, Priya R; Tamm, Eric P; Qayyum, Aliya; Crane, Christopher H; Javle, Milind; Katz, Matthew H; Gottumukkala, Vijaya N; Rozner, Marc A; Shen, Haifa; Lee, Jeffrey E; Wang, Huamin; Chen, Yuling; Plunkett, William; Abbruzzese, James L; Wolff, Robert A; Maitra, Anirban; Ferrari, Mauro; Varadhachary, Gauri R; Fleming, Jason B

    2014-01-01

    There is substantial heterogeneity in the clinical behavior of pancreatic cancer and in its response to therapy. Some of this variation may be due to differences in delivery of cytotoxic therapies between patients and within individual tumors. Indeed, in 12 patients with resectable pancreatic cancer, we previously demonstrated wide inter-patient variability in the delivery of gemcitabine as well as in the mass transport properties of tumors as measured by computed tomography (CT) scans. However, the variability of drug delivery and transport properties within pancreatic tumors is currently unknown. Here, we analyzed regional measurements of gemcitabine DNA incorporation in the tumors of the same 12 patients to understand the degree of intra-tumoral heterogeneity of drug delivery. We also developed a volumetric segmentation approach to measure mass transport properties from the CT scans of these patients and tested inter-observer agreement with this new methodology. Our results demonstrate significant heterogeneity of gemcitabine delivery within individual pancreatic tumors and across the patient cohort, with gemcitabine DNA incorporation in the inner portion of the tumors ranging from 38 to 74% of the total. Similarly, the CT-derived mass transport properties of the tumors had a high degree of heterogeneity, ranging from minimal difference to almost 200% difference between inner and outer portions of the tumor. Our quantitative method to derive transport properties from CT scans demonstrated less than 5% difference in gemcitabine prediction at the average CT-derived transport value across observers. These data illustrate significant inter-patient and intra-tumoral heterogeneity in the delivery of gemcitabine, and highlight how this variability can be reproducibly accounted for using principles of mass transport. With further validation as a biophysical marker, transport properties of tumors may be useful in patient selection for therapy and prediction of

  18. Intra-tumoral heterogeneity of gemcitabine delivery and mass transport in human pancreatic cancer

    PubMed Central

    Koay, Eugene J.; Baio, Flavio E.; Ondari, Alexander; Truty, Mark J.; Cristini, Vittorio; Thomas, Ryan M.; Chen, Rong; Chatterjee, Deyali; Kang, Ya’an; Zhang, Joy; Court, Laurence; Bhosale, Priya R.; Tamm, Eric P.; Qayyum, Aliya; Crane, Christopher H.; Javle, Milind; Katz, Matthew H.; Gottumukkala, Vijaya N.; Rozner, Marc A.; Shen, Haifa; Lee, Jeffrey E.; Wang, Huamin; Chen, Yuling; Plunkett, William; Abbruzzese, James L.; Wolff, Robert A.; Maitra, Anirban; Ferrari, Mauro; Varadhachary, Gauri R.; Fleming, Jason B.

    2014-01-01

    There is substantial heterogeneity in the clinical behavior of pancreatic cancer and in its response to therapy. Some of this variation may be due to differences in delivery of cytotoxic therapies between patients and within individual tumors. Indeed, in 12 patients with resectable pancreatic cancer, we previously demonstrated wide inter-patient variability in the delivery of gemcitabine as well as in the mass transport properties of tumors as measured by computed tomography (CT) scans. However, the variability of drug delivery and transport properties within pancreatic tumors is currently unknown. Here, we analyzed regional measurements of gemcitabine DNA incorporation in the tumors of the same 12 patients to understand the degree of intra-tumoral heterogeneity of drug delivery. We also developed a volumetric segmentation approach to measure mass transport properties from the CT scans of these patients and tested inter-observer agreement with this new methodology. Our results demonstrate significant heterogeneity of gemcitabine delivery within individual pancreatic tumors and across the patient cohort, with gemcitabine DNA incorporation in the inner portion of the tumors ranging from 38 to 74% of the total. Similarly, the CT-derived mass transport properties of the tumors had a high degree of heterogeneity, ranging from minimal difference to almost 200% difference between inner and outer portions of the tumor. Our quantitative method to derive transport properties from CT scans demonstrated less than 5% difference in gemcitabine prediction at the average CT-derived transport value across observers. These data illustrate significant inter-patient and intra-tumoral heterogeneity in the delivery of gemcitabine, and highlight how this variability can be reproducibly accounted for using principles of mass transport. With further validation as a biophysical marker, transport properties of tumors may be useful in patient selection for therapy and prediction of

  19. Intra-tumoral heterogeneity of gemcitabine delivery and mass transport in human pancreatic cancer

    NASA Astrophysics Data System (ADS)

    Koay, Eugene J.; Baio, Flavio E.; Ondari, Alexander; Truty, Mark J.; Cristini, Vittorio; Thomas, Ryan M.; Chen, Rong; Chatterjee, Deyali; Kang, Ya'an; Zhang, Joy; Court, Laurence; Bhosale, Priya R.; Tamm, Eric P.; Qayyum, Aliya; Crane, Christopher H.; Javle, Milind; Katz, Matthew H.; Gottumukkala, Vijaya N.; Rozner, Marc A.; Shen, Haifa; Lee, Jeffrey E.; Wang, Huamin; Chen, Yuling; Plunkett, William; Abbruzzese, James L.; Wolff, Robert A.; Maitra, Anirban; Ferrari, Mauro; Varadhachary, Gauri R.; Fleming, Jason B.

    2014-12-01

    There is substantial heterogeneity in the clinical behavior of pancreatic cancer and in its response to therapy. Some of this variation may be due to differences in delivery of cytotoxic therapies between patients and within individual tumors. Indeed, in 12 patients with resectable pancreatic cancer, we previously demonstrated wide inter-patient variability in the delivery of gemcitabine as well as in the mass transport properties of tumors as measured by computed tomography (CT) scans. However, the variability of drug delivery and transport properties within pancreatic tumors is currently unknown. Here, we analyzed regional measurements of gemcitabine DNA incorporation in the tumors of the same 12 patients to understand the degree of intra-tumoral heterogeneity of drug delivery. We also developed a volumetric segmentation approach to measure mass transport properties from the CT scans of these patients and tested inter-observer agreement with this new methodology. Our results demonstrate significant heterogeneity of gemcitabine delivery within individual pancreatic tumors and across the patient cohort, with gemcitabine DNA incorporation in the inner portion of the tumors ranging from 38 to 74% of the total. Similarly, the CT-derived mass transport properties of the tumors had a high degree of heterogeneity, ranging from minimal difference to almost 200% difference between inner and outer portions of the tumor. Our quantitative method to derive transport properties from CT scans demonstrated less than 5% difference in gemcitabine prediction at the average CT-derived transport value across observers. These data illustrate significant inter-patient and intra-tumoral heterogeneity in the delivery of gemcitabine, and highlight how this variability can be reproducibly accounted for using principles of mass transport. With further validation as a biophysical marker, transport properties of tumors may be useful in patient selection for therapy and prediction of

  20. Geomorphological characteristics and variability of Holocene mass-transport complexes, St. Lawrence River Estuary, Canada

    NASA Astrophysics Data System (ADS)

    Pinet, Nicolas; Brake, Virginia; Campbell, Calvin; Duchesne, Mathieu J.

    2015-01-01

    Recently acquired multibeam bathymetry data are used to investigate seafloor instability features along a 310 km-long segment of the St. Lawrence River Estuary. The analysis of this dataset indicates that submarine slides occur over a much larger area than previously recognized and that Holocene sediments are reworked by mass-transport along significant portions of both the northwest and southeast margins of the Laurentian Channel. In the surveyed area, 96 individual mass-transport complexes (MTCs) were identified representing 13% of the seabed. MTCs vary in area from less than 1 km2 to more than 40 km2 and exhibit various geomorphological signatures. Qualitative observation reveals an apparent disparity between MTCs that remain coherent and those that disintegrate during downslope transport evolving into a blocky morphological signature. For all MTCs, morphological parameters have been measured (area, length, and height) or calculated (slope and roughness). This quantitative analysis provides a unique opportunity to study these parameters in a statistically significant and homogeneous dataset located in a relatively small area that experienced a similar Quaternary history. In many cases, mass transport events appear to initiate in the vicinity of steep bedrock walls located along some segments of the estuary. The timing of mass-transport events was not constrained during this study. However, the fact that the region hosts the Charlevoix seismic zone, the most tectonically active area in eastern Canada, strongly suggests that earthquakes acted as a trigger for submarine landsliding.

  1. Mass Transport and Turbulence in Gravitationally Unstable Disk Galaxies. II: The Effects of Star Formation Feedback

    NASA Astrophysics Data System (ADS)

    Goldbaum, Nathan J.; Krumholz, Mark R.; Forbes, John C.

    2016-08-01

    Self-gravity and stellar feedback are capable of driving turbulence and transporting mass and angular momentum in disk galaxies, but the balance between them is not well understood. In the previous paper in this series, we showed that gravity alone can drive turbulence in galactic disks, regulate their Toomre Q parameters to ∼1, and transport mass inwards at a rate sufficient to fuel star formation in the centers of present-day galaxies. In this paper we extend our models to include the effects of star formation feedback. We show that feedback suppresses galaxies’ star formation rates by a factor of ∼5 and leads to the formation of a multi-phase atomic and molecular interstellar medium. Both the star formation rate and the phase balance produced in our simulations agree well with observations of nearby spirals. After our galaxies reach steady state, we find that the inclusion of feedback actually lowers the gas velocity dispersion slightly compared to the case of pure self-gravity, and also slightly reduces the rate of inward mass transport. Nevertheless, we find that, even with feedback included, our galactic disks self-regulate to Q ∼ 1, and transport mass inwards at a rate sufficient to supply a substantial fraction of the inner disk star formation. We argue that gravitational instability is therefore likely to be the dominant source of turbulence and transport in galactic disks, and that it is responsible for fueling star formation in the inner parts of galactic disks over cosmological times.

  2. Pesticide Transport with Runoff from Creeping Bentgrass Turf: Relationship of Pesticide Properties to Mass Transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The off-site transport of pesticides with runoff is both an agronomic and environmental concern resulting from reduced control of target pests in the area of application and contamination of surrounding ecosystems. Experiments were designed to measure the quantity of pesticides in runoff from creepi...

  3. Mass and momentum turbulent transport experiments with confined swirling coaxial jets

    NASA Technical Reports Server (NTRS)

    Roback, R.; Johnson, B. V.

    1983-01-01

    Swirling coaxial jets mixing downstream, discharging into an expanded duct was conducted to obtain data for the evaluation and improvement of turbulent transport models currently used in a variety of computational procedures throughout the combustion community. A combination of laser velocimeter (LV) and laser induced fluorescence (LIF) techniques was employed to obtain mean and fluctuating velocity and concentration distributions which were used to derive mass and momentum turbulent transport parameters currently incorporated into various combustor flow models. Flow visualization techniques were also employed to determine qualitatively the time dependent characteristics of the flow and the scale of turbulence. The results of these measurements indicated that the largest momentum turbulent transport was in the r-z plane. Peak momentum turbulent transport rates were approximately the same as those for the nonswirling flow condition. The mass turbulent transport process for swirling flow was complicated. Mixing occurred in several steps of axial and radial mass transport and was coupled with a large radial mean convective flux. Mixing for swirling flow was completed in one-third the length required for nonswirling flow.

  4. Mass transport properties of Pu/DT mixtures from orbital free molecular dynamics simulations

    SciTech Connect

    Kress, Joel David; Ticknor, Christopher; Collins, Lee A.

    2015-09-16

    Mass transport properties (shear viscosity and diffusion coefficients) for Pu/DT mixtures were calculated with Orbital Free Molecular Dynamics (OFMD). The results were fitted to simple functions of mass density (for ρ=10.4 to 62.4 g/cm3) and temperature (for T=100 up to 3,000 eV) for Pu/DT mixtures consisting of 100/0, 25/75, 50/50, and 75/25 by number.

  5. Determination of O₂ Mass Transport at the Pt | PFSA Ionomer Interface under Reduced Relative Humidity.

    PubMed

    Novitski, David; Holdcroft, Steven

    2015-12-16

    Oxygen mass transport resistance through the ionomer component in the cathode catalyst layer is considered to contribute overpotential losses in polymer electrolyte membrane fuel cells. Whereas it is known that water uptake, water transport, and proton conductivity are reduced upon reducing relative humidity, the effect on oxygen mass transport remains unknown. We report a two-electrode approach to determine mass transport coefficients for the oxygen reduction reaction in air at the Pt/perfluorosulfonic acid ionomer membrane interface between 90 and 30% RH at 70 °C using a Pt microdisk in a solid state electrochemical cell. Potential-step chronoamperometry was performed at specific mass-transport limiting potentials to allow for the elucidation of the oxygen diffusion coefficient (D(bO2)) and oxygen concentration (c(bO2)). In our efforts, novel approaches in data acquisition, as well as analysis, were examined because of the dynamic nature of the membrane under lowered hydration conditions. Linear regression analysis reveals a decrease in oxygen permeability (D(bO2c(bO2)) by a factor of 1.7 and 3.4 from 90 to 30% RH for Nafion 211 membrane and membranes cast from Nafion DE2020 ionomer solutions, respectively. Additionally, nonlinear curve fitting by way of the Shoup-Szabo equation is employed to analyze the entire current transient during potential step controlled ORR. We also report on the presence of an RH dependence of our previously reported time-dependency measurements for O2 mass transport coefficients. PMID:26583742

  6. Mass transport and alloying during InN growth on GaN by molecular-beam epitaxy

    SciTech Connect

    Liu, Y.; Xie, M.H.; Wu, H.S.; Tong, S.Y.

    2006-05-29

    During Stranski-Krastanov (SK) growth of InN on GaN by molecular-beam epitaxy, a mass transport is noted from the two-dimensional wetting layer and/or the surface excess metal adlayers to the SK islands when the excess nitrogen flux is used for deposition. The extent of mass transport depends on the material coverage. For growth under the excess indium flux condition, no such mass transport is observed.

  7. Modification of the finite element heat and mass transfer code (FEHM) to model multicomponent reactive transport

    SciTech Connect

    Viswanathan, H.S.

    1996-08-01

    The finite element code FEHMN, developed by scientists at Los Alamos National Laboratory (LANL), is a three-dimensional finite element heat and mass transport simulator that can handle complex stratigraphy and nonlinear processes such as vadose zone flow, heat flow and solute transport. Scientists at LANL have been developing hydrologic flow and transport models of the Yucca Mountain site using FEHMN. Previous FEHMN simulations have used an equivalent Kd model to model solute transport. In this thesis, FEHMN is modified making it possible to simulate the transport of a species with a rigorous chemical model. Including the rigorous chemical equations into FEHMN simulations should provide for more representative transport models for highly reactive chemical species. A fully kinetic formulation is chosen for the FEHMN reactive transport model. Several methods are available to computationally implement a fully kinetic formulation. Different numerical algorithms are investigated in order to optimize computational efficiency and memory requirements of the reactive transport model. The best algorithm of those investigated is then incorporated into FEHMN. The algorithm chosen requires for the user to place strongly coupled species into groups which are then solved for simultaneously using FEHMN. The complete reactive transport model is verified over a wide variety of problems and is shown to be working properly. The new chemical capabilities of FEHMN are illustrated by using Los Alamos National Laboratory`s site scale model of Yucca Mountain to model two-dimensional, vadose zone {sup 14}C transport. The simulations demonstrate that gas flow and carbonate chemistry can significantly affect {sup 14}C transport at Yucca Mountain. The simulations also prove that the new capabilities of FEHMN can be used to refine and buttress already existing Yucca Mountain radionuclide transport studies.

  8. Measurements of Combined Axial Mass and Heat Transport in He II.

    ERIC Educational Resources Information Center

    Johnson, Warren W.; Jones, Michael C.

    An experiment was performed that allowed measurements of both axial mass and heat transport of He-II (the superfluid phase of helium 4) in a long tube. The apparatus allowed the pressure difference and the temperature difference across the flow tube to each be independently adjusted, and the resulting steady-state values of net fluid velocity and…

  9. Mean Flow Velocities and Mass Transport for Equatorially-Trapped Water Waves with an Underlying Current

    NASA Astrophysics Data System (ADS)

    Henry, David; Sastre-Gomez, Silvia

    2016-04-01

    In this paper we present an analysis of the mean flow velocities, and related mass transport, which are induced by certain equatorially-trapped water waves. In particular, we examine a recently-derived exact and explicit solution to the geophysical governing equations in the {β} -plane approximation at the equator which incorporates a constant underlying current.

  10. Momentum and mass transport over a superhydrophobic bubble mattress: the influence of interface geometry

    NASA Astrophysics Data System (ADS)

    Tsai, Peichun Amy; Haase, A. Sander; Karatay, Elif; Lammertink, Rob; Soft Matter, Fluidics; Interfaces Group Team

    2013-11-01

    We numerically investigate the influence of interface geometry on momentum and mass transport on a partially slippery bubble mattress. The bubble mattress, forming a superhydrophobic substrate, consists of an array of slippery (shear-free) gas bubbles with (no-slip) solids walls in between. We consider steady pressure-driven laminar flow over the bubble mattress, with a solute being supplied from the gas bubbles. The results show that solute transport can be enhanced significantly due to effective slippage, compared to a fully saturated no-slip wall. The enhancement depends on the interface geometry of the bubble mattress, i.e. on the bubble size, protrusion angle, and surface porosity. In addition, we demonstrate that the mass transfer enhancement disappears below a critical bubble size. The effective slip vanishes for very small bubbles, whereby interfacial transport becomes diffusion dominated. For large bubbles, solute transport near the interface is greatly enhanced by convection. The results provide insight into the optimal design of ultra-hydrophobic bubble mattresses to enhance both momentum and mass transport.