Directed flow fluid rinse trough

DOEpatents

Kempka, S.N.; Walters, R.N.

1996-07-02

Novel rinse troughs accomplish thorough uniform rinsing. The tanks are suitable for one or more essentially planar items having substantially the same shape. The troughs ensure that each surface is rinsed uniformly. The new troughs also require less rinse fluid to accomplish a thorough rinse than prior art troughs. 9 figs.

Organimetallic Fluorescent Complex Polymers For Light Emitting Applications

DOEpatents

Shi, Song Q.; So, Franky

1997-10-28

A fluorescent complex polymer with fluorescent organometallic complexes connected by organic chain spacers is utilized in the fabrication of light emitting devices on a substantially transparent planar substrate by depositing a first conductive layer having p-type conductivity on the planar surface of the substrate, depositing a layer of a hole transporting and electron blocking material on the first conductive layer, depositing a layer of the fluorescent complex polymer on the layer of hole transporting and electron blocking material as an electron transporting emissive layer and depositing a second conductive layer having n-type conductivity on the layer of fluorescent complex polymer.

Planar multijunction high voltage solar cells

NASA Technical Reports Server (NTRS)

Evans, J. C., Jr.; Chai, A. T.; Goradia, C.

1980-01-01

Technical considerations, preliminary results, and fabrication details are discussed for a family of high-voltage planar multi-junction (PMJ) solar cells which combine the attractive features of planar cells with conventional or interdigitated back contacts and the vertical multijunction (VMJ) solar cell. The PMJ solar cell is internally divided into many voltage-generating regions, called unit cells, which are internally connected in series. The key to obtaining reasonable performance from this device was the separation of top surface field regions over each active unit cell. Using existing solar cell fabricating methods, output voltages in excess of 20 volts per linear centimeter are possible. Analysis of the new device is complex, and numerous geometries are being studied which should provide substantial benefits in both normal sunlight usage as well as with concentrators.

The planar multijunction cell - A new solar cell for earth and space

NASA Technical Reports Server (NTRS)

Evans, J. C., Jr.; Chai, A.-T.; Goradia, C.

1980-01-01

A new family of high-voltage solar cells, called the planar multijunction (PMJ) cell is being developed. The new cells combine the attractive features of planar cells with conventional or interdigitated back contacts and the vertical multijunction (VMJ) solar cell. The PMJ solar cell is internally divided into many voltage-generating regions, called unit cells, which are internally connected in series. The key to obtaining reasonable performance from this device was the separation of top surface field regions over each active unit cell area. Using existing solar cell fabricating methods, output voltages in excess of 20 volts per linear centimeter are possible. Analysis of the new device is complex, and numerous geometries are being studied which should provide substantial benefits in both normal sunlight usage as well as with concentrators.

[DNA complexes, formed on aqueous phase surfaces: new planar polymeric and composite nanostructures].

PubMed

Antipina, M N; Gaĭnutdinov, R V; Rakhnianskaia, A A; Sergeev-Cherenkov, A N; Tolstikhina, A L; Iurova, T V; Kislov, V V; Khomutov, G B

2003-01-01

The formation of DNA complexes with Langmuir monolayers of the cationic lipid octadecylamine (ODA) and the new amphiphilic polycation poly-4-vinylpyridine with 16% of cetylpyridinium groups (PVP-16) on the surface of an aqueous solution of native DNA of low ionic strength was studied. Topographic images of Langmuir-Blodgett films of DNA/ODA and DNA/PVP-16 complexes applied to micaceous substrates were investigated by the method of atomic force microscopy. It was found that films of the amphiphilic polycation have an ordered planar polycrystalline structure. The morphology of planar DNA complexes with the amphiphilic cation substantially depended on the incubation time and the phase state of the monolayer on the surface of the aqueous DNA solution. Complex structures and individual DNA molecules were observed on the surface of the amphiphilic monolayer. Along with quasi-linear individual bound DNA molecules, characteristic extended net-like structures and quasi-circular toroidal condensed conformations of planar DNA complexes were detected. Mono- and multilayer films of DNA/PVP-16 complexes were used as templates and nanoreactors for the synthesis of inorganic nanostructures via the binding of metal cations from the solution and subsequent generation of the inorganic phase. As a result, ultrathin polymeric composite films with integrated DNA building blocks and quasi-linear arrays of inorganic semiconductor (CdS) and iron oxide nanoparticles and nanowires were obtained. The nanostructures obtained were characterized by scanning probe microscopy and transmission electron microscopy techniques. The methods developed are promising for investigating the mechanisms of structural organization and transformation in DNA and polyelectrolyte complexes at the gas-liquid interface and for the design of new extremely thin highly ordered planar polymeric and composite materials, films, and coatings with controlled ultrastructure for applications in nanoelectronics and nanobiotechnology.

On-line, continuous monitoring in solar cell and fuel cell manufacturing using spectral reflectance imaging

DOEpatents

Sopori, Bhushan; Rupnowski, Przemyslaw; Ulsh, Michael

2016-01-12

A monitoring system 100 comprising a material transport system 104 providing for the transportation of a substantially planar material 102, 107 through the monitoring zone 103 of the monitoring system 100. The system 100 also includes a line camera 106 positioned to obtain multiple line images across a width of the material 102, 107 as it is transported through the monitoring zone 103. The system 100 further includes an illumination source 108 providing for the illumination of the material 102, 107 transported through the monitoring zone 103 such that light reflected in a direction normal to the substantially planar surface of the material 102, 107 is detected by the line camera 106. A data processing system 110 is also provided in digital communication with the line camera 106. The data processing system 110 is configured to receive data output from the line camera 106 and further configured to calculate and provide substantially contemporaneous information relating to a quality parameter of the material 102, 107. Also disclosed are methods of monitoring a quality parameter of a material.

Method and apparatus for fabrication of high gradient insulators with parallel surface conductors spaced less than one millimeter apart

DOEpatents

Sanders, David M.; Decker, Derek E.

1999-01-01

Optical patterns and lithographic techniques are used as part of a process to embed parallel and evenly spaced conductors in the non-planar surfaces of an insulator to produce high gradient insulators. The approach extends the size that high gradient insulating structures can be fabricated as well as improves the performance of those insulators by reducing the scale of the alternating parallel lines of insulator and conductor along the surface. This fabrication approach also substantially decreases the cost required to produce high gradient insulators.

Frame-mounted wire management device

DOEpatents

Grushkowitz, Tyler; Fischer, Kevin; Danning, Matthew

2016-09-20

A wire management device is disclosed. The device comprises a clip comprising an upper planar member and a lower planar member, each planar member having an inner and outer surface, wherein the inner surface of the upper planar member includes a post extending toward the inner surface of the lower planar member, a stem extending from the outer surface of the lower planar member, the stem including two outwardly-extending flanges, each of the first and second outwardly-extending flanges including an edge portion extending toward the outer surface of the lower planar member, and a transverse passage extending along the outer surface of the lower planar member, the transverse passage extending across the stem, wherein the stem has a recessed portion along the transverse passage.

Generalized non-local surface susceptibility model and Fresnel coefficients for the characterization of periodic metafilms with bianisotropic scatterers

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

Dimitriadis, Alexandros I., E-mail: aldimitr@ee.auth.gr; Kantartzis, Nikolaos V., E-mail: kant@auth.gr; Tsiboukis, Theodoros D., E-mail: tsibukis@auth.gr

2015-01-15

Highlights: •Formulas for E/M fields radiated by continuous surface polarization distributions. •Non-local effective surface susceptibility model for periodic metafilms. •Generalized reflection and transmission coefficients for an arbitrary metafilm. •Successful treatment of non-planar scatterer arrays and spatial dispersion effects. -- Abstract: A non-local surface susceptibility model for the consistent description of periodic metafilms formed by arbitrarily-shaped, electrically-small, bianisotropic scatterers is developed in this paper. The rigorous scheme is based on the point-dipole approximation technique and is valid for any polarization and propagation direction of an electromagnetic wave impinging upon the metafilm, unlike existing approaches whose applicability is practically confined to verymore » specific cases of incidence. Next, the universal form of the resulting surface susceptibility matrix is employed for the derivation of the generalized Fresnel coefficients for such surfaces, which enable the comprehensive interpretation of several significant, yet relatively unexamined, physical interactions. Essentially, these coefficients include eight distinct terms, corresponding to the co-polarized and cross-polarized reflection and transmission coefficients for the two orthogonal eigenpolarizations of a linearly-polarized incident plane wave. The above formulas are, then, utilized for the prediction of the scattering properties of metafilms with different planar and non-planar resonators, which are characterized via the featured model and two previously reported local ones. Their comparison with numerical simulation outcomes substantiates the merits of the proposed method, reveals important aspects of the underlying physics, and highlights the differences between the various modeling procedures.« less

Dielectric Covered Planar Antennas

NASA Technical Reports Server (NTRS)

Llombart Juan, Nuria (Inventor); Lee, Choonsup (Inventor); Chattopadhyay, Goutam (Inventor); Gill, John J. (Inventor); Skalare, Anders J. (Inventor); Siegel, Peter H. (Inventor)

2014-01-01

An antenna element suitable for integrated arrays at terahertz frequencies is disclosed. The antenna element comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g. silicon, antenna fed by a leaky wave waveguide feed. The extended spherical lens comprises a substantially spherical lens adjacent a substantially planar lens extension. A couple of TE/TM leaky wave modes are excited in a resonant cavity formed between a ground plane and the substantially planar lens extension by a waveguide block coupled to the ground plane. Due to these modes, the primary feed radiates inside the lens with a directive pattern that illuminates a small sector of the lens. The antenna structure is compatible with known semiconductor fabrication technology and enables production of large format imaging arrays.

Method for laser welding a fin and a tube

DOEpatents

Fuerschbach, Phillip W.; Mahoney, A. Roderick; Milewski, John O

2001-01-01

A method of laser welding a planar metal surface to a cylindrical metal surface is provided, first placing a planar metal surface into approximate contact with a cylindrical metal surface to form a juncture area to be welded, the planar metal surface and cylindrical metal surface thereby forming an acute angle of contact. A laser beam, produced, for example, by a Nd:YAG pulsed laser, is focused through the acute angle of contact at the juncture area to be welded, with the laser beam heating the juncture area to a welding temperature to cause welding to occur between the planar metal surface and the cylindrical metal surface. Both the planar metal surface and cylindrical metal surface are made from a reflective metal, including copper, copper alloys, stainless steel alloys, aluminum, and aluminum alloys.

Strained-layer superlattice focal plane array having a planar structure

DOEpatents

Kim, Jin K [Albuquerque, NM; Carroll, Malcolm S [Albuquerque, NM; Gin, Aaron [Albuquerque, NM; Marsh, Phillip F [Lowell, MA; Young, Erik W [Albuquerque, NM; Cich, Michael J [Albuquerque, NM

2010-07-13

An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

Strained layer superlattice focal plane array having a planar structure

DOEpatents

Kim, Jin K; Carroll, Malcolm S; Gin, Aaron; Marsh, Phillip F; Young, Erik W; Cich, Michael J

2012-10-23

An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

Permanent magnet edge-field quadrupole

DOEpatents

Tatchyn, R.O.

1997-01-21

Planar permanent magnet edge-field quadrupoles for use in particle accelerating machines and in insertion devices designed to generate spontaneous or coherent radiation from moving charged particles are disclosed. The invention comprises four magnetized rectangular pieces of permanent magnet material with substantially similar dimensions arranged into two planar arrays situated to generate a field with a substantially dominant quadrupole component in regions close to the device axis. 10 figs.

Permanent magnet edge-field quadrupole

DOEpatents

Tatchyn, Roman O.

1997-01-01

Planar permanent magnet edge-field quadrupoles for use in particle accelerating machines and in insertion devices designed to generate spontaneous or coherent radiation from moving charged particles are disclosed. The invention comprises four magnetized rectangular pieces of permanent magnet material with substantially similar dimensions arranged into two planar arrays situated to generate a field with a substantially dominant quadrupole component in regions close to the device axis.

Carbon Nanotube Tower-Based Supercapacitor

NASA Technical Reports Server (NTRS)

Meyyappan, Meyya (Inventor)

2012-01-01

A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

D-section structural tubes

NASA Technical Reports Server (NTRS)

Leete, II, John H. (Inventor); Skinner, William J. (Inventor)

1989-01-01

Structural members for a frame or truss are formed of two substantially identical elongated tubular like members each having a planar extending wall with the tubular members joined together along the planar wall, back to back, and end portions of the joined planar walls form extending lugs. A complementary joint fitting includes a clevis having a slot for receiving the lug.

Site-Control of InAs/GaAs Quantum Dots with Indium-Assisted Deoxidation

PubMed Central

Hussain, Sajid; Pozzato, Alessandro; Tormen, Massimo; Zannier, Valentina; Biasiol, Giorgio

2016-01-01

Site-controlled epitaxial growth of InAs quantum dots on GaAs substrates patterned with periodic nanohole arrays relies on the deterministic nucleation of dots into the holes. In the ideal situation, each hole should be occupied exactly by one single dot, with no nucleation onto planar areas. However, the single-dot occupancy per hole is often made difficult by the fact that lithographically-defined holes are generally much larger than the dots, thus providing several nucleation sites per hole. In addition, deposition of a thin GaAs buffer before the dots tends to further widen the holes in the [110] direction. We have explored a method of native surface oxide removal by using indium beams, which effectively prevents hole elongation along [110] and greatly helps single-dot occupancy per hole. Furthermore, as compared to Ga-assisted deoxidation, In-assisted deoxidation is efficient in completely removing surface contaminants, and any excess In can be easily re-desorbed thermally, thus leaving a clean, smooth GaAs surface. Low temperature photoluminescence showed that inhomogeneous broadening is substantially reduced for QDs grown on In-deoxidized patterns, with respect to planar self-assembled dots. PMID:28773333

Seasonal control skylight glazing panel with passive solar energy switching

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

Miller, J.V.

1983-10-25

A substantially transparent one-piece glazing panel is provided for generally horizontal mounting in a skylight. The panel is comprised of an repeated pattern of two alternating and contiguous linear optical elements; a first optical element being an upstanding generally right-triangular linear prism, and the second optical element being an upward-facing plano-cylindrical lens in which the planar surface is reflectively opaque and is generally in the same plane as the base of the triangular prism.

Thin film hydrogen sensor

DOEpatents

Cheng, Yang-Tse; Poli, Andrea A.; Meltser, Mark Alexander

1999-01-01

A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

Method of fabricating a photovoltaic module of a substantially transparent construction

NASA Technical Reports Server (NTRS)

Dillard, P. A.; Fritz, W. M.; Lott, D. R. (Inventor)

1980-01-01

A method characterized by the steps of positioning a plurality of uniformly dimensioned photovoltaic cells in registered relation with a plurality of openings formed in a planar tool is disclosed. The method allows acess to the P contact surface of each of the cells. The steps of the method are: (1) connecting the N contact surface of alternate cells to the P contact surface of the cells interposed therebetween, (2) removing therefrom residue of solder flux, (3) applying to the N contact surfaces of the cells a transparent adhesive, (4) placing a common transparent cover plate in engaged relation with the adhesive, (5) placing a film over the circular openings for hermetically sealing the openings, and (6) establishing a vacuum between the film and the cover plate.

Apparatus for checking the direction of polarization of shear-wave ultrasonic transducers

DOEpatents

Karplus, Henry H. B.

1980-01-01

An apparatus for checking the direction of polarization of shear-wave ultrasonic transducers comprises a first planar surface for mounting the shear-wave transducer, a second planar surface inclined at a predetermined angle to the first surface to generate longitudinal waves by mode conversion, and a third planar surface disposed at a second predetermined angle to the first for mounting a longitudinal-wave ultrasonic transducer. In an alternate embodiment, two second planar surfaces at the predetermined angle are placed at an angle to each other. The magnitude of the shear wave is a function of the angle between the direction of polarization of the transducer and the mode-conversion surface.

Apparatus for checking the direction of polarization of shear-wave ultrasonic transducers

DOEpatents

Karplus, H.H.B.; Forster, G.A.

An apparatus for checking the direction of polarization of shear-wave ultrasonic transducers comprises a first planar surface for mounting the shear-wave transducer, a second planar surface inclined at a predetermined angle to the first surface to generate longitudinal waves by mode conversion, and a third planar surface disposed at a second predetermined angle to the first for mounting a longitudinal-wave ultransonic transducer. In an alternate embodiment, two second planar surfaces at the predetermined angle are placed at an angle to each other. The magnitude of the shear wave is a function of the angle between the direction of polarization of the transducer and the mode-conversion surface.

Ceramic tip cast in valve rocker arm

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

Tashiro, K.

1986-12-09

This patent describes a cast ceramic tip for a rocker arm of an automotive engine, a slipper block having a contoured cam engaging surface extending longitudinally of one face thereof, and having a retainer block formed integrally with the slipper block and extending substantially perpendicular to an opposite face of the slipper block. The retainer block has opposite longitudinally extending faces and opposite laterally extending faces. The improvement described here comprises: radiused fillets extending laterally of the opposite faces of the slipper block, and providing transitions between the opposite face thereof and the opposite laterally extending faces of the retainermore » block; and, retaining channels formed exclusively in the longitudinally extending faces of the retainer block, the laterally extending faces being substantially planar.« less

Thin film hydrogen sensor

DOEpatents

Cheng, Y.T.; Poli, A.A.; Meltser, M.A.

1999-03-23

A thin film hydrogen sensor includes a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end. 5 figs.

Photovoltaic Cell Having A P-Type Polycrystalline Layer With Large Crystals

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes R.

1996-03-26

A photovoltaic cell has an n-type polycrystalline layer and a p-type polycrystalline layer adjoining the n-type polycrystalline layer to form a photovoltaic junction. The p-type polycrystalline layer comprises a substantially planar layer portion having relatively large crystals adjoining the n-type polycrystalline layer. The planar layer portion includes oxidized impurities which contribute to obtainment of p-type electrical properties in the planar layer portion.

Predicting optical and thermal characteristics of transparent single-glazed domed skylights

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

Laouadi, A.; Atif, M.R.

1999-07-01

Optical and thermal characteristics of domed skylights are important to solve the trade-off between daylighting and thermal design. However, there is a lack of daylighting and thermal design tools for domed skylights. Optical and thermal characteristics of transparent single-glazed hemispherical domed skylights under sun and sky light are evaluated based on an optical model for domed skylights. The optical model is based on tracing the beam and diffuse radiation transmission through the dome surface. A simple method is proposed to replace single-glazed hemispherical domed skylights by optically and thermally equivalent single-glazed planar skylights to accommodate limitations of energy computer programs.more » Under sunlight, single-glazed hemispherical domed skylights yield slightly lower equivalent solar transmittance and solar heat gain coefficient (SHGC) at near normal zenith angles than those of single-glazed planar skylights. However, single-glazed hemispherical domed skylights yield substantially higher equivalent solar transmittance and SHGC at high zenith angles and around the horizon. Under isotropic skylight, single-glazed hemispherical domed skylights yield slightly lower equivalent solar transmittance and SHGC than those of single-glazed planar skylights. Daily solar heat gains of single-glazed hemispherical domed skylights are higher than those of single-glazed horizontal planar skylights in both winter and summer. In summer, the solar heat gain of single-glazed hemispherical domed skylights can reach 3% to 9% higher than those of horizontal single-glazed planar skylights for latitudes varying between 0 and 55{degree} (north/south). In winter, however, the solar heat gains of single-glazed hemispherical domed skylights increase significantly with the increase of the site latitude and can reach 232% higher than those of horizontal single-glazed planar skylights, particularly for high latitude countries.« less

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

Sun, Liang; Akgun, Bulent; Narayanan, Suresh

Swollen polymer brushes are found in many systems where the brush is intended to mediate interactions with the surroundings. The surface height fluctuations of planar polystyrene brushes (0.04 – 0.63 chains/nm2) highly swollen in toluene vapor are so strongly slowed by the tethering of the chains that they are unobservable in the current experimental window of length and time. This is the case despite the fact that the segmental dynamics of the brush chains should be very fast due to the substantial plasticization by the solvent. With respect to thermally stimulated fluctuations, the surfaces of these swollen brushes are solid-likemore » on time scales and length scales pertinent to many practical applications.« less

Process Of Bonding A Metal Brush Structure To A Planar Surface Of A Metal Substrate

DOEpatents

Slattery, Kevin T.; Driemeyer, Daniel E.; Wille; Gerald W.

1999-11-02

Process for bonding a metal brush structure to a planar surface of a metal substrate in which an array of metal rods are retained and immobilized at their tips by a common retention layer formed of metal, and the brush structure is then joined to a planar surface of a metal substrate via the retention layer.

Planar Impacts in Rollover Crashes: Significance, Distribution and Injury Epidemiology

PubMed Central

Bose, Dipan; Kerrigan, Jason R.; Foster, Jonathan B.; Crandall, Jeff R.; Tobaru, Shigeo

2011-01-01

While one third of all fatal motor vehicle crashes involve rollover of the vehicle, a substantially large portion of these rollover crashes involve planar impacts (e.g., frontal, side or rear impact) that influence the crash kinematics and subsequently the injury outcome. The objective of the study was to evaluate the distribution of planar impacts in rollover crashes, and in particular, to describe the differences in the underlying crash kinematics, injury severity and the regional distribution of injuries when compared to the rollover-dominated crashes without significant planar impact (i.e., primary rollovers). Sampled cases (n=6,900) from the U.S. National Automotive Sampling System – Crashworthiness Data System, representing approximately 3.3 million belted drivers involved in a rollover crash in years 1998–2008, were analyzed. Single vehicle rollover crashes with significant planar impact (21% of all rollover crashes) were in general more likely to result in occupant fatality and involved higher incidence of moderate to severe injuries compared to single vehicle primary rollovers (p<0.05). A substantial proportion of the planar impact rollovers ended in single quarter turn crashes (30%), mostly resulting from a frontal impact (59%). While chest was the most frequently injured body region among all rollover victims sustaining severe injuries, severe injuries sustained in primary rollovers were more isolated (single body region) in comparison to the ones sustained in rollovers with planar impacts. The results emphasize the higher risk of rollover victims sustaining an injury and the differences in distribution of injuries sustained when a planar impact is associated with the rollover crash. PMID:22105400

Ion-damage-free planarization or shallow angle sectioning of solar cells for mapping grain orientation and nanoscale photovoltaic properties

DOE PAGES

Kutes, Yasemin; Luria, Justin; Sun, Yu; ...

2017-04-11

Ion beam milling is the most common modern method for preparing specific features for microscopic analysis, even though concomitant ion implantation and amorphization remain persistent challenges, particularly as they often modify materials properties of interest. Atomic force microscopy (AFM), on the other hand, can mechanically mill specific nanoscale regions in plan-view without chemical or high energy ion damage, due to its resolution, directionality, and fine load control. As an example, AFM-nanomilling (AFM-NM) is implemented for top-down planarization of polycrystalline CdTe thin film solar cells, with a resulting decrease in the root mean square (RMS) roughness by an order of magnitude,more » even better than for a low incidence FIB polished surface. Subsequently AFM-based property maps reveal a substantially stronger contrast, in this case of the short-circuit current or open circuit voltage during light exposure. Furthermore, electron back scattering diffraction (EBSD) imaging also becomes possible upon AFM-NM, enabling direct correlations between the local materials properties and the polycrystalline microstructure. Smooth shallow-angle cross-sections are demonstrated as well, based on targeted oblique milling. As expected, this reveals a gradual decrease in the average short-circuit current and maximum power as the underlying CdS and electrode layers are approached, but a relatively consistent open-circuit voltage through the diminishing thickness of the CdTe absorber. AFM-based nanomilling is therefore a powerful tool for material characterization, uniquely providing ion-damage free, selective area, planar smoothing or low-angle sectioning of specimens while preserving their functionality. This then enables novel, co-located advanced AFM measurements, EBSD analysis, and investigations by related techniques that are otherwise hindered by surface morphology or surface damage.« less

Ion-damage-free planarization or shallow angle sectioning of solar cells for mapping grain orientation and nanoscale photovoltaic properties

NASA Astrophysics Data System (ADS)

Kutes, Yasemin; Luria, Justin; Sun, Yu; Moore, Andrew; Aguirre, Brandon A.; Cruz-Campa, Jose L.; Aindow, Mark; Zubia, David; Huey, Bryan D.

2017-05-01

Ion beam milling is the most common modern method for preparing specific features for microscopic analysis, even though concomitant ion implantation and amorphization remain persistent challenges, particularly as they often modify materials properties of interest. Atomic force microscopy (AFM), on the other hand, can mechanically mill specific nanoscale regions in plan-view without chemical or high energy ion damage, due to its resolution, directionality, and fine load control. As an example, AFM-nanomilling (AFM-NM) is implemented for top-down planarization of polycrystalline CdTe thin film solar cells, with a resulting decrease in the root mean square (RMS) roughness by an order of magnitude, even better than for a low incidence FIB polished surface. Subsequent AFM-based property maps reveal a substantially stronger contrast, in this case of the short-circuit current or open circuit voltage during light exposure. Electron back scattering diffraction (EBSD) imaging also becomes possible upon AFM-NM, enabling direct correlations between the local materials properties and the polycrystalline microstructure. Smooth shallow-angle cross-sections are demonstrated as well, based on targeted oblique milling. As expected, this reveals a gradual decrease in the average short-circuit current and maximum power as the underlying CdS and electrode layers are approached, but a relatively consistent open-circuit voltage through the diminishing thickness of the CdTe absorber. AFM-based nanomilling is therefore a powerful tool for material characterization, uniquely providing ion-damage free, selective area, planar smoothing or low-angle sectioning of specimens while preserving their functionality. This enables novel, co-located advanced AFM measurements, EBSD analysis, and investigations by related techniques that are otherwise hindered by surface morphology or surface damage.

Inkjet-based adaptive planarization (Conference Presentation)

NASA Astrophysics Data System (ADS)

Singhal, Shrawan; Grigas, Michelle M.; Khusnatdinov, Niyaz; Sreenivasan, Srinivasan V.

2017-03-01

Planarization is a critical unit step in the lithography process because it enables patterning of surfaces with versatile pattern density without compromising on the stringent planarity and depth-of-focus requirements. In addition to nanoscale pattern density variation, parasitics such as pre-existing wafer topography, can corrupt the desired process output after planarization. The topography of any surface can be classified in three broad categories, depending upon the amplitude and spatial wavelength of the same [1], [2]: (i) nominal shape, (ii) nanotopography and (iii) roughness. The nominal shape is given by the largest spatial wavelengths, typically < 20mm. For spatial length scales of 1-20mm, height variations at this spatial wavelength range are classified as nanotopography. Roughness usually has lower spatial wavelengths. While the nominal shape of a substrate surface is usually decided by the nature of wafer preparation and the tooling and chucking infrastructure used in the same, roughness is usually mitigated by standard polishing techniques. It is the intermediate nanotopography that is probably the most critical surface topography parameter. This is because most traditional polishing techniques cannot selectively address pre-existing substrate topography, without introducing a parasitic signature at the scale of nanotopography. Moreover, fields with pattern density variation typically also have length scales that are commensurate with nanotopography. It is thus instructive to summarize existing planarization technology to understand current limitations. Spin on Glass and Etch back is one technique used for micron scale device manufacturing [3]. As the name implies, a glass dielectric is spin-coated on the substrate followed by etching in a chemistry that ensures equal etching rates for both the sacrificial glass and the underlying film or substrate material. Photoresists may also be used instead of glass. However, the global planarity that can be achieved by this technique is limited. Also, planarization over a large isolated topographical feature has been studied for the reverse-tone Jet-and-Flash Imprint Lithography process, also known as JFIL-R [4]. This relies on surface tension and capillary effects to smoothen a spin-coated Si containing film that can be etched to obtain a smooth profile. To meet the stringent requirement of planarity in submicron device technologies Chemical Mechanical Planarization (CMP) is the most widely used planarization technology [5], [6]. It uses a combination of abrasive laden chemical slurry and a mechanical pad for achieving planar profiles. The biggest concern with CMP is the dependence of material removal rate on the pattern density of material, leading to the formation of a step between the high density and low-density. The step shows up as a long-range thickness variation in the planarized film, similar in scale to pre-existing substrate topography that should have been polished away. Preventive techniques like dummy fill and patterned resist can be used to reduce the variation in pattern density. These techniques increase the complexity of the planarization process and significantly limit the device design flexibility. Contact Planarization (CP) has also been reported as an alternative to the CMP processing [7], [8]. A substrate is spin coated with a photo curable material and pre baked to remove residual solvent. An ultra-flat surface or an optical flat is pressed on the spin-coated wafer. The material is forced to reflow. Pressure is used to spread out material evenly and achieve global planarization. The substrate is then exposed to UV radiation to harden the photo curable material. Although attractive, this process is not adaptive as it does not account for differences in surface topography of the wafer and the optical flat, nor can it address all the parasitics that arise during the process itself. The optical flat leads to undesirable planarization of even the substrate nominal shape and nanotopography, which corrupts the final film thickness profile. Hence, it becomes extremely difficult to eliminate this signature to a desirable extent without introducing other parasitic signatures. An example of this is shown in Figure 1. In this paper, a novel adaptive planarization process has been presented that potentially addresses the problems associated with planarization of varying pattern density, even in the presence of pre-existing substrate topography [9]. This process is called Inkjet-enabled Adaptive Planarization (IAP). The IAP process uses an inverse optimization scheme, built around a validated fluid mechanics-based forward model [10], that takes the pre-existing substrate topography and pattern layout as inputs. It then generates an inkjet drop pattern with a material distribution that is correlated with the desired planarization film profile. This allows a contiguous film to be formed with the desired thickness variation to cater to the topography and any parasitic signatures caused by the pattern layout. This film is formed by the coercing action of a compliant superstrate, which forces the drops to spread and merge and eliminates any bubble trapping. Then, the film is cured using blanket UV exposure and the superstrate separated to reveal the desired planarized film. The use of an inverse optimization algorithm allows substrate topography to be addressed adaptively. In other words, the algorithm can generate a drop pattern that does not disturb the pre-existing substrate topography substantially, but only caters to the pattern density variation. This process has potential advantages over other planarization techniques because of its adaptive nature. Hence, the IAP process can cater to substrates of varying topographies and pattern densities by changing the inkjetted material distribution, without any changes in hardware. The IAP process can also address pre-existing substrate topography selectively by conforming to the nominal shape while planarizing over the pattern layout. A schematic of the IAP process is shown in Figure 2. The goal of this paper is to present some preliminary results from the IAP process. A test pattern layout has been generated with the help of photolithography, and is shown in Figure 3. For the purpose of this trial, the nanoscale features have not been patterned, as it is expected that the planarization process will be blind to their presence. Thus, areas with nanoscale patterns have been patterned as a single feature of SiO2 with height equal to 100 nm. These features are adjacent to pattern-less areas, thus marking a drastic change in pattern density. As can be seen in Figure 4, the smallest length scale across which pattern density changes, is 70 microns. The goal of the IAP process is to be able to planarize this pattern with a film that conforms to pre-existing substrate topography. The targeted planarity of the film is 95% 3sigma, while the targeted film thickness at the tallest feature is less than 30 nm. In another trial, the inverse tone of the same layout will also be tested. This pattern has features of height equal to 100 nm where the previous pattern did not. The targeted metrics for the inverse layout are the same as the nominal layout.

Electrolytic Cell For Production Of Aluminum Employing Planar Anodes.

DOEpatents

Barnett, Robert J.; Mezner, Michael B.; Bradford, Donald R

2004-10-05

A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising providing a molten salt electrolyte having alumina dissolved therein in an electrolytic cell. A plurality of anodes and cathodes having planar surfaces are disposed in a generally vertical orientation in the electrolyte, the anodes and cathodes arranged in alternating or interleaving relationship to provide anode planar surfaces disposed opposite cathode planar surfaces, the anode comprised of carbon. Electric current is passed through anodes and through the electrolyte to the cathodes depositing aluminum at the cathodes and forming carbon containing gas at the anodes.

Multiple Optical Traps with a Single-Beam Optical Tweezer Utilizing Surface Micromachined Planar Curved Grating

NASA Astrophysics Data System (ADS)

Kuo, Ju-Nan; Chen, Kuan-Yu

2010-11-01

In this paper, we present a single-beam optical tweezer integrated with a planar curved diffraction grating for microbead manipulation. Various curvatures of the surface micromachined planar curved grating are systematically investigated. The planar curved grating was fabricated using multiuser micro-electro-mechanical-system (MEMS) processes (MUMPs). The angular separation and the number of diffracted orders were determined. Experimental results indicate that the diffraction patterns and curvature of the planar curved grating are closely related. As the curvature of the planar curved grating increases, the vertical diffraction angle increases, resulting in the strip patterns of the planar curved grating. A single-beam optical tweezer integrated with a planar curved diffraction grating was developed. We demonstrate a technique for creating multiple optical traps from a single laser beam using the developed planar curved grating. The strip patterns of the planar curved grating that resulted from diffraction were used to trap one row of polystyrene beads.

Focusing corner cube

DOEpatents

Monjes, J.A.

1985-09-12

This invention retortreflects and focuses a beam of light. The invention comprises a modified corner cube reflector wherein one reflective surface is planar, a second reflective surface is spherical, and the third reflective surface may be planar or convex cylindrical.

Fluorescence-correlation spectroscopy study of molecular transport within reversed-phase chromatographic particles compared to planar model surfaces.

PubMed

Cooper, Justin; Harris, Joel M

2014-12-02

Reversed-phase liquid chromatography (RPLC) is a widely used technique for molecular separations. Stationary-phase materials for RPLC generally consist of porous silica-gel particles functionalized with n-alkane ligands. Understanding motions of molecules within the interior of these particles is important for developing efficient chromatographic materials and separations. To characterize these dynamics, time-resolved spectroscopic methods (photobleach recovery, fluorescence correlation, single-molecule imaging) have been adapted to measure molecular diffusion rates, typically at n-alkane-modified planar silica surfaces, which serve as models of chromatographic interfaces. A question arising from these studies is how dynamics of molecules on a planar surface relate to motions of molecules within the interior of a porous chromatographic particle. In this paper, imaging-fluorescence-correlation spectroscopy is used to measure diffusion rates of a fluorescent probe molecule 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI) within authentic RPLC porous silica particles and compared with its diffusion at a planar C18-modified surface. The results show that surface diffusion on the planar C18 substrate is much faster than the diffusion rate of the probe molecule through a chromatographic particle. Surface diffusion within porous particles, however, is governed by molecular trajectories along the tortuous contours of the interior surface of the particles. By accounting for the greater surface area that a molecule must explore to diffuse macroscopic distances through the particle, the molecular-scale diffusion rates on the two surfaces can be compared, and they are virtually identical. These results provide support for the relevance of surface-diffusion measurements made on planar model surfaces to the dynamic behavior of molecules on the internal surfaces of porous chromatographic particles.

Piezoelectric resonator assembly with thin molybdenum mounting clips

DOEpatents

Peters, R. Donald

1981-01-01

A resonator mounting assembly wherein the resonator blank is mounted agai an essentially planar surface presented by a plurality of peripherally disposed mounting clips and bonded to this surface to provide substantially all the mechanical support for the blank in a direction normal to the major faces of the resonator blank, while being flexible in the directions parallel to said major faces so as to minimize radial stresses on the resonator blank, particularly during thermal cycling of the resonator assembly. The clips are fabricated of a low thermal expansion material, such as molybdenum, which also has considerable yield strength after exposure to processing temperatures; the bonding of the clips to the edges of the resonator blank can be achieved by a polyimide containing electrically conductive particles.

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

DOEpatents

Leung, Ka-Ngo; Gordon, K.C.; Kippenhan, D.O.; Purgalis, P.; Moussa, D.; Williams, M.D.; Wilde, S.B.; West, M.W.

1987-10-16

A large area directly heated lanthanum hexaboride (LaB/sub 6/) cathode system is disclosed. The system comprises a LaB/sub 6/ cathode element generally circular in shape about a central axis. The cathode element has a head with an upper substantially planar emission surface, and a lower downwardly and an intermediate body portion which diminishes in cross-section from the head towards the base of the cathode element. A central rod is connected to the base of the cathode element and extends along the central axis. Plural upstanding spring fingers are urged against an outer peripheral contact surface of the head end to provide a mechanical and electrical connection to the cathode element. 7 figs

Ion-beam-induced planarization, densification, and exfoliation of low-density nanoporous silica

NASA Astrophysics Data System (ADS)

Kucheyev, S. O.; Shin, S. J.

2017-09-01

Planarization of low-density nanoporous solids is challenging. Here, we demonstrate that ion bombardment to doses of ˜1015 cm-2 results in significant smoothing of silica aerogels, yielding mirror-like surfaces after metallization. The surface smoothing efficiency scales with the ion energy loss component leading to local lattice heating. Planarization is accompanied by sub-surface monolith densification, resulting in surface exfoliation with increasing ion dose. These findings have implications for the fabrication of graded-density nanofoams, aerogel-based lightweight optical components, and meso-origami.

Control of target-normal-sheath-accelerated protons from a guiding cone

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

Zou, D. B.; Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf, Düsseldorf 40225; Zhuo, H. B., E-mail: hongbin.zhuo@gmail.com

2015-06-15

It is demonstrated through particle-in-cell simulations that target-normal-sheath-accelerated protons can be well controlled by using a guiding cone. Compared to a conventional planar target, both the collimation and number density of proton beams are substantially improved, giving a high-quality proton beam which maintained for a longer distance without degradation. The effect is attributed to the radial electric field resulting from the charge due to the hot target electrons propagating along the cone surface. This electric field can effectively suppress the spatial spread of the protons after the expansion of the hot electrons.

Gamma ray detector modules

NASA Technical Reports Server (NTRS)

Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

2009-01-01

A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.

Dynamical analysis of surface-insulated planar wire array Z-pinches

NASA Astrophysics Data System (ADS)

Li, Yang; Sheng, Liang; Hei, Dongwei; Li, Xingwen; Zhang, Jinhai; Li, Mo; Qiu, Aici

2018-05-01

The ablation and implosion dynamics of planar wire array Z-pinches with and without surface insulation are compared and discussed in this paper. This paper first presents a phenomenological model named the ablation and cascade snowplow implosion (ACSI) model, which accounts for the ablation and implosion phases of a planar wire array Z-pinch in a single simulation. The comparison between experimental data and simulation results shows that the ACSI model could give a fairly good description about the dynamical characteristics of planar wire array Z-pinches. Surface insulation introduces notable differences in the ablation phase of planar wire array Z-pinches. The ablation phase is divided into two stages: insulation layer ablation and tungsten wire ablation. The two-stage ablation process of insulated wires is simulated in the ACSI model by updating the formulas describing the ablation process.

Study of curved and planar frequency-selective surfaces with nonplanar illumination

NASA Technical Reports Server (NTRS)

Caroglanian, Armen; Webb, Kevin J.

1991-01-01

A locally planar technique (LPT) is investigated for determining the forward-scattered field from a generally shaped inductive frequency-selective surface (FSS) with nonplanar illumination. The results of an experimental study are presented to assess the LPT accuracy. The effects of a nonplanar incident field are determined by comparing the LPT numerical results with a series of experiments with the feed source placed at varying distances from the planar FSS. The limitations of the LPT model due to surface curvature are investigated in an experimental study of the scattered fields from a set of hyperbolic cylinders of different curvatures. From these comparisons, guidelines for applying the locally planar technique are developed.

Registration of immunoglobuline AB/AG reaction with planar polarization interferometer

NASA Astrophysics Data System (ADS)

Nabok, Alexei V.; Starodub, Nickolaj F.; Ray, Asim K.; Hassan, Aseel K.

2000-12-01

Immobilization of human immunoglobuline (IgG) (AG) and goat on human IGG antibodies (AB) as well as AB/AG specific reaction were studied with planar polarization interferometry (PPI). In this novel method, polarized laser beam was coupled into the planar waveguide made on silicon wafer and consisted of 20nm Si3N4 layer sandwiched between two 1.5 micrometers SiO2 layers with the sensing window etched in the top SIO2 layer. One of the immune components was deposited by means of polyelectrolyte self- assembly on top of the Si3N3 layer within the sensing window, P-component of the polarized light is sensitive to adsorption, while s-component serves as a reference. Thus the outcoming light intensity depends on the phase shift between s- and p-components. Different sequences of immobilization of the immune components were studied with both surface plasmon resonance (SPR) and PPI methods. It was shown that predeposition of a monolayer of protein A, which is believed to affect the orientation of the immune components, causes an additional increase in the sensitivity. PPI method allowed us to improve substantially the sensitivity towards AB/AG reaction as compared to traditional SPR method. Particularly, of specific binding of 3ng/ml AG was registered.

Planar regions of GaAs (001) prepared by Ga droplet motion

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

Zheng, Changxi, E-mail: changxi.zheng@monash.edu; Tang, Wen-Xin; Jesson, David E., E-mail: jessonDE@cardiff.ac.uk

2016-07-15

The authors describe a simple method for obtaining planar regions of GaAs (001) suitable for surface science studies. The technique, which requires no buffer layer growth, atomic hydrogen source, or the introduction of As flux, employs controllable Ga droplet motion to create planar trail regions during Langmuir evaporation. Low-energy electron microscopy/diffraction techniques are applied to monitor the droplet motion and characterize the morphology and the surface reconstruction. It is found that the planar regions exhibit atomic flatness at the level of a high-quality buffer layer.

Isolated planar gyroscope with internal radial sensing and actuation

NASA Technical Reports Server (NTRS)

Challoner, A. Dorian (Inventor); Shcheglov, Kirill V. (Inventor)

2006-01-01

The present invention discloses an inertial sensor comprising a planar mechanical resonator with embedded sensing and actuation for substantially in-plane vibration and having a central rigid support for the resonator. At least one excitation or torquer electrode is disposed within an interior of the resonator to excite in-plane vibration of the resonator and at least one sensing or pickoff electrode is disposed within the interior of the resonator for sensing the motion of the excited resonator. In one embodiment, the planar resonator includes a plurality of slots in an annular pattern; in another embodiment, the planar mechanical resonator comprises four masses; each embodiment having a simple degenerate pair of in-plane vibration modes.

Multi-projector auto-calibration and placement optimization for non-planar surfaces

NASA Astrophysics Data System (ADS)

Li, Dong; Xie, Jinghui; Zhao, Lu; Zhou, Lijing; Weng, Dongdong

2015-10-01

Non-planar projection has been widely applied in virtual reality and digital entertainment and exhibitions because of its flexible layout and immersive display effects. Compared with planar projection, a non-planar projection is more difficult to achieve because projector calibration and image distortion correction are difficult processes. This paper uses a cylindrical screen as an example to present a new method for automatically calibrating a multi-projector system in a non-planar environment without using 3D reconstruction. This method corrects the geometric calibration error caused by the screen's manufactured imperfections, such as an undulating surface or a slant in the vertical plane. In addition, based on actual projection demand, this paper presents the overall performance evaluation criteria for the multi-projector system. According to these criteria, we determined the optimal placement for the projectors. This method also extends to surfaces that can be parameterized, such as spheres, ellipsoids, and paraboloids, and demonstrates a broad applicability.

Support assembly having three dimension position adjustment capabilities

DOEpatents

Cutburth, Ronald W.; House, F. Allen

1987-01-01

An assembly for supporting an apparatus such as a microscope or laser to and against a planar surface is disclosed herein. This apparatus includes three specific arrangements for adjusting the positions of three segments of the apparatus so as to adjust the position of the overall apparatus with respect to the planar surface in the x-, y-and z-directions, where the x-direction and the y-direction are both parallel with the planar surface and perpendicular to one another and where the z-direction is perpendicular to the planar surface and the x-and y-directions. Each of two of the three arrangements includes its own means for providing x-, y- and z-adjustments (which includes rotation in the x, y plane) while it is only necessary for the third arrangement to provide adjustments in the z-direction.

SFG characterization of a cationic ONLO dye in biological thin films

NASA Astrophysics Data System (ADS)

Johnson, Lewis E.; Casford, Michael T.; Elder, Delwin L.; Davies, Paul B.; Johal, Malkiat S.

2013-10-01

Biopolymer-based thin films, such as those composed of CTMA-DNA, can be used as a host material for NLOactive dyes for applications such as electro-optic (EO) switching and second harmonic generation. Previous work by Heckman et al. (Proc. SPIE 6401, 640108-2) has demonstrated functioning DNA-based EO modulators. Improved performance requires optimization of both the first hyperpolarizabilities (β) and degree of acentric ordering exhibited by the chromophores. The cationic dye DANPY-1 (Proc. SPIE 8464, 846409-D) has a high affinity for DNA and a substantial hyperpolarizability; however, its macroscopic ordering has not been previously characterized. We have characterized the acentric ordering of the dye using sum-frequency generation (SFG) vibrational spectroscopy in surface-immobilized DNA and on planar metal and dielectric surfaces.

Compact ion chamber based neutron detector

DOEpatents

Derzon, Mark S.; Galambos, Paul C.; Renzi, Ronald F.

2015-10-27

A directional neutron detector has an ion chamber formed in a dielectric material; a signal electrode and a ground electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; readout circuitry which is electrically coupled to the signal and ground electrodes; and a signal processor electrically coupled to the readout circuitry. The ion chamber has a pair of substantially planar electrode surfaces. The chamber pressure of the neutron absorbing material is selected such that the reaction particle ion trail length for neutrons absorbed by the neutron absorbing material is equal to or less than the distance between the electrode surfaces. The signal processor is adapted to determine a path angle for each absorbed neutron based on the rise time of the corresponding pulse in a time-varying detector signal.

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

DOEpatents

Leung, Ka-Ngo; Gordon, Keith C.; Kippenham, Dean O.; Purgalis, Peter; Moussa, David; Williams, Malcom D.; Wilde, Stephen B.; West, Mark W.

1989-01-01

A large area directly heated lanthanum hexaboride (LaB.sub.6) cathode system (10) is disclosed. The system comprises a LaB.sub.6 cathode element (11) generally circular in shape about a central axis. The cathode element (11) has a head (21) with an upper substantially planar emission surface (23), and a lower downwardly and an intermediate body portion (26) which diminishes in cross-section from the head (21) towards the base (22) of the cathode element (11). A central rod (14) is connected to the base (22) of the cathode element (11) and extends along the central axis. Plural upstanding spring fingers (37) are urged against an outer peripheral contact surface (24) of the head end (21) to provide a mechanical and electrical connection to the cathode element (11).

An incremental double-layer capacitance of a planar nano gap and its application in cardiac-troponin T detection.

PubMed

Hsueh, Hsiao-Ting; Lin, Chih-Ting

2016-05-15

Surface potential is one of the most important properties at solid-liquid interfaces. It can be modulated by the voltage applied on the electrode or by the surface properties. Hence, surface potential is a good indicator for surface modifications, such as biomolecular bindings. In this work, we proposed a planar nano-gap structure for surface-potential difference monitoring. Based on the proposed architecture, the variance of surface-potential difference can be determined by electrical double layer capacitance (EDLC) between the nano-gap electrodes. Using cyclic voltammetry method, in this work, we demonstrated a relationship between surface potential and EDLC by chemically modifying surface properties. Finally, we also showed the proposed planar nano-gap device provides the capability for cardiac-troponin T (cTnT) measurements with co-existed 10 µg/ml BSA interference. The detection dynamic range is from 100 pg/ml to 1 µg/ml. Based on experimental results and extrapolation, the detection limit is less than 100 pg/ml in diluted PBS buffer (0.01X PBS). These results demonstrated the planar nano-gap architecture having potentials on biomolecular detection through monitoring of surface-potential variation. Copyright © 2015 Elsevier B.V. All rights reserved.

Triple bar, high efficiency mechanical sealer

DOEpatents

Pak, Donald J.; Hawkins, Samantha A.; Young, John E.

2013-03-19

A clamp with a bottom clamp bar that has a planar upper surface is provided. The clamp may also include a top clamp bar connected to the bottom clamp bar, and a pressure distribution bar between the top clamp bar and the bottom clamp bar. The pressure distribution bar may have a planar lower surface in facing relation to the upper surface of the bottom clamp bar. An object is capable of being disposed in a clamping region between the upper surface and the lower surface. The width of the planar lower surface may be less than the width of the upper surface within the clamping region. Also, the pressure distribution bar may be capable of being urged away from the top clamp bar and towards the bottom clamp bar.

Dynamics of collision of a vortex ring and a planar surface

NASA Astrophysics Data System (ADS)

McErlean, Michael; Krane, Michael; Fontaine, Arnold

2008-11-01

The dynamics of the impact between a vortex ring and a planar surface is presented. The vortex rings, generated by piston injection of a slug of water into a quiescent water tank, collide with a surface oriented normally to the ring's direction of travel. The time evolution of both the force imparted to a planar surface and the wall pressure are presented. These are supplemented by DPIV measurements of the evolution of ring strength and structure, before and during impact. The relation between changes in ring structure during collision and the waveforms of impact force and wall pressure will be discussed.

A high figure of merit localized surface plasmon sensor based on a gold nanograting on the top of a gold planar film

NASA Astrophysics Data System (ADS)

Zhang, Zu-Yin; Wang, Li-Na; Hu, Hai-Feng; Li, Kang-Wen; Ma, Xun-Peng; Song, Guo-Feng

2013-10-01

We investigate the sensitivity and figure of merit (FOM) of a localized surface plasmon (LSP) sensor with gold nanograting on the top of planar metallic film. The sensitivity of the localized surface plasmon sensor is 317 nm/RIU, and the FOM is predicted to be above 8, which is very high for a localized surface plasmon sensor. By employing the rigorous coupled-wave analysis (RCWA) method, we analyze the distribution of the magnetic field and find that the sensing property of our proposed system is attributed to the interactions between the localized surface plasmon around the gold nanostrips and the surface plasmon polarition on the surface of the gold planar metallic film. These findings are important for developing high FOM localized surface plasmon sensors.

Development of advanced second-generation micromirror devices fabricated in a four-level planarized surface-micromachined polycrystalline silicon process

NASA Astrophysics Data System (ADS)

Michalicek, M. Adrian; Comtois, John H.; Schriner, Heather K.

1998-04-01

This paper describes the design and characterization of several types of micromirror devices to include process capabilities, device modeling, and test data resulting in deflection versus applied potential curves and surface contour measurements. These devices are the first to be fabricated in the state-of-the-art four-level planarized polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology. This enabling process permits the development of micromirror devices with near-ideal characteristics which have previously been unrealizable in standard three-layer polysilicon processes. This paper describes such characteristics which have previously been unrealizable in standard three-layer polysilicon processes. This paper describes such characteristics as elevated address electrodes, various address wiring techniques, planarized mirror surfaces suing Chemical Mechanical Polishing, unique post-process metallization, and the best active surface area to date.

Optical fiber head for providing lateral viewing

DOEpatents

Everett, Matthew J.; Colston, Billy W.; James, Dale L.; Brown, Steve; Da Silva, Luiz

2002-01-01

The head of an optical fiber comprising the sensing probe of an optical heterodyne sensing device includes a planar surface that intersects the perpendicular to axial centerline of the fiber at a polishing angle .theta.. The planar surface is coated with a reflective material so that light traveling axially through the fiber is reflected transverse to the fiber's axial centerline, and is emitted laterally through the side of the fiber. Alternatively, the planar surface can be left uncoated. The polishing angle .theta. must be no greater than 39.degree. or must be at least 51.degree.. The emitted light is reflected from adjacent biological tissue, collected by the head, and then processed to provide real-time images of the tissue. The method for forming the planar surface includes shearing the end of the optical fiber and applying the reflective material before removing the buffer that circumscribes the cladding and the core.

Asymmetries in surface waves and reflection/transmission characteristics associated with topological insulators

NASA Astrophysics Data System (ADS)

Mackay, Tom G.; Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio; Lakhtakia, Akhlesh

2017-08-01

Three numerical studies were undertaken involving the interactions of plane waves with topological insulators. In each study, the topologically insulating surface states of the topological insulator were represented through a surface admittance. Canonical boundary-value problems were solved for the following cases: (i) Dyakonov surface-wave propagation guided by the planar interface of a columnar thin film and an isotropic dielectric topological insulator; (ii) Dyakonov-Tamm surface-wave propagation guided by the planar interface of a structurally chiral material and an isotropic dielectric topological insulator; and (iii) reflection and transmission due to the planar interface of a topologically insulating columnar thin film and vacuum. The nonzero surface admittance resulted in asymmetries in the wave speeds and decay constants of the surface waves in studies (i) and (ii). The nonzero surface admittance resulted in asymmetries in the reflectances and transmittances in study (iii).

Radiative flux from a planar multiple point source within a cylindrical enclosure reaching a coaxial circular plane

NASA Astrophysics Data System (ADS)

Tryka, Stanislaw

2007-04-01

A general formula and some special integral formulas were presented for calculating radiative fluxes incident on a circular plane from a planar multiple point source within a coaxial cylindrical enclosure perpendicular to the source. These formula were obtained for radiation propagating in a homogeneous isotropic medium assuming that the lateral surface of the enclosure completely absorbs the incident radiation. Exemplary results were computed numerically and illustrated with three-dimensional surface plots. The formulas presented are suitable for determining fluxes of radiation reaching planar circular detectors, collectors or other planar circular elements from systems of laser diodes, light emitting diodes and fiber lamps within cylindrical enclosures, as well as small biological emitters (bacteria, fungi, yeast, etc.) distributed on planar bases of open nontransparent cylindrical containers.

Effects of planar and non-planar driver-side mirrors on age-related discomfort-glare responses

PubMed Central

Lockhart, Thurmon E.; Atsumi, Bunji; Ghosh, Arka; Mekaroonreung, Haruetai; Spaulding, Jeremy

2010-01-01

In this study, we evaluated subjective nighttime discomfort-glare responses on three different types of planar and non-planar driver-side mirrors on two age groups. Fifty-six individuals (28 young [18–35 years] and 28 old [65 years and over]) participated in this experiment. Subjective discomfort-glare rating scores on three different types of driver-side mirrors were assessed utilizing De Boer's rating scale in a controlled nighttime driving environment (laboratory ambient illuminant level—l lux with headlight turned off). Three driver-side mirrors included planar “flat mirror”: radius of curvature 242650.92 mm, reflectivity 0.60114, and surface reflectance 0.60568; “curved mirror”: radius of curvature 1433.3 mm, reflectivity 0.21652, and surface reflectance 0.58092; “blue mirror”: radius of curvature 1957.1 mm, reflectivity 0.25356, and surface reflectance 0.54585. The results indicated that with the same glare level (as measured by angle of incidence and illuminance in front of the eyes), older adults reported worse feelings of glare than their younger counterparts. Furthermore, the results indicated that both young and older adults reported worse feelings of glare for planar driver-side mirror than non-planar driver-side mirrors. These results suggest that older adults' criterion of discomfort-glare is more sensitive than their younger counterparts, and importantly, the non-planar driver-side mirrors can be beneficial in terms of reducing nighttime discomfort-glare for both the young and the elderly. PMID:20582252

LPI studies with grazing incidence irradiation at the Nike laser

NASA Astrophysics Data System (ADS)

Weaver, J.; Kehne, D.; Schmitt, A.; Obenschain, S.; Serlin, V.; Oh, J.; Lehmberg, R.; Seely, J.

2013-10-01

Studies of laser plasma instabilities (LPI) at the Nike laser facility at NRL have previously concentrated on planar targets irradiated with their surface normal aligned to the central axis of the laser. Shots with planar targets rotated up 60° to the laser have shown changes in thresholds for the two-plasmon decay instability and stimulated Raman scattering near the quarter critical region. In the case of rotated low-Z targets, spectra were observed to shift to lower wavelength and were substantially stronger in the visible and ultraviolet spectral ranges. The low-Z target data show growth at an incident intensity slightly below (~30%) the threshold values observed at normal incidence. A rapid rise in signal level over the same laser intensities was also observed in the hard x-ray data which serve as an overall indicator of LPI activity. Shots with rotated planar high-Z targets showed that the visible and ultraviolet emissions dropped significantly when compared to low-Z targets in the same geometry. This presentation will include results from upcoming experiments to determine the LPI signal for low-Z, high-Z, and high-Z coated targets at lower laser intensities for several angles of target rotation. Shots with widely separated laser beams are also planned to explore cross beam energy transport at Nike. Work supported by DoE/NNSA.

Highly sensitive surface-enhanced Raman scattering substrate made from superaligned carbon nanotubes.

PubMed

Sun, Yinghui; Liu, Kai; Miao, Jiao; Wang, Zheyao; Tian, Baozhong; Zhang, Lina; Li, Qunqing; Fan, Shoushan; Jiang, Kaili

2010-05-12

Surface-enhanced Raman scattering (SERS) has attracted wide attention because it can enhance normally weak Raman signal by several orders of magnitude and facilitate the sensitive detection of molecules. Conventional SERS substrates are constructed by placing metal nanoparticles on a planar surface. Here we show that, if the planar surface was substituted by a unique nanoporous surface, the enhancement effect can be dramatically improved. The nanoporous surface can be easily fabricated in batches and at low costs by cross stacking superaligned carbon nanotube films. The as-prepared transparent and freestanding SERS substrate is capable of detecting ambient trinitrotoluene vapor, showing much higher Raman enhancement than ordinary planar substrates because of the extremely large surface area and the unique zero-dimensional at one-dimensional nanostructure. These results not only provide a new approach to ultrasensitive SERS substrates, but also are helpful for improving the fundamental understanding of SERS phenomena.

Acoustic propagation operators for pressure waves on an arbitrarily curved surface in a homogeneous medium

NASA Astrophysics Data System (ADS)

Sun, Yimin; Verschuur, Eric; van Borselen, Roald

2018-03-01

The Rayleigh integral solution of the acoustic Helmholtz equation in a homogeneous medium can only be applied when the integral surface is a planar surface, while in reality almost all surfaces where pressure waves are measured exhibit some curvature. In this paper we derive a theoretically rigorous way of building propagation operators for pressure waves on an arbitrarily curved surface. Our theory is still based upon the Rayleigh integral, but it resorts to matrix inversion to overcome the limitations faced by the Rayleigh integral. Three examples are used to demonstrate the correctness of our theory - propagation of pressure waves acquired on an arbitrarily curved surface to a planar surface, on an arbitrarily curved surface to another arbitrarily curved surface, and on a spherical cap to a planar surface, and results agree well with the analytical solutions. The generalization of our method for particle velocities and the calculation cost of our method are also discussed.

Optimized micromirror arrays for adaptive optics

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

Michalicek, M. Adrian

This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 {mu}m minimum feature sizes and 0.1 {mu}m mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces canmore » be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2{endash}3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98{percent} or better. Combining the process planarization with a {open_quotes}planarized-by-design{close_quotes} approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics. {copyright} {ital 1999 American Institute of Physics.}« less

Geometrically induced surface polaritons in planar nanostructured metallic cavities

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

Davids, P. S.; Intravia, F; Dalvit, Diego A.

2014-01-14

We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer atmore » short separations.« less

Enhanced and tunable electric dipole-dipole interactions near a planar metal film

NASA Astrophysics Data System (ADS)

Zhou, Lei-Ming; Yao, Pei-Jun; Zhao, Nan; Sun, Fang-Wen

2017-08-01

We investigate the enhanced electric dipole-dipole interaction of surface plasmon polaritons (SPPs) supported by a planar metal film waveguide. By taking two nitrogen-vacancy (NV) center electric dipoles in diamond as an example, both the coupling strength and collective relaxation of two dipoles are studied with the numerical Green Function method. Compared to two-dipole coupling on a planar surface, metal film provides stronger and tunable coupling coefficients. Enhancement of the interaction between coupled NV center dipoles could have applications in both quantum information and energy transfer investigation. Our investigation provides systematic results for experimental applications based on a dipole-dipole interaction mediated with SPPs on a planar metal film.

Summing Feynman graphs by Monte Carlo: Planar ϕ3-theory and dynamically triangulated random surfaces

NASA Astrophysics Data System (ADS)

Boulatov, D. V.; Kazakov, V. A.

1988-12-01

New combinatorial identities are suggested relating the ratio of (n - 1)th and nth orders of (planar) perturbation expansion for any quantity to some average over the ensemble of all planar graphs of the nth order. These identities are used for Monte Carlo calculation of critical exponents γstr (string susceptibility) in planar ϕ3-theory and in the dynamically triangulated random surface (DTRS) model near the convergence circle for various dimensions. In the solvable case D = 1 the exact critical properties of the theory are reproduced numerically. After August 3, 1988 the address will be: Cybernetics Council, Academy of Science, ul. Vavilova 40, 117333 Moscow, USSR.

A magnetic resonance (MR) microscopy system using a microfluidically cryo-cooled planar coil.

PubMed

Koo, Chiwan; Godley, Richard F; Park, Jaewon; McDougall, Mary P; Wright, Steven M; Han, Arum

2011-07-07

We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (-196 °C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: (1) the small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. (2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0 °C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system resulted in an average image SNR enhancement of 1.47 ± 0.11 times relative to similar room-temperature coils. This journal is © The Royal Society of Chemistry 2011

A Magnetic Resonance (MR) Microscopy System using a Microfluidically Cryo-Cooled Planar Coil

PubMed Central

Koo, Chiwan; Godley, Richard F.; Park, Jaewon; McDougall, Mary P.; Wright, Steven M.; Han, Arum

2011-01-01

We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (−196°C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: 1) The small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. 2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0°C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system resulted in an average image SNR enhancement of 1.47 ± 0.11 times relative to similar room-temperature coils. PMID:21603723

Ultra-high density diffraction grating

DOEpatents

Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.

2012-12-11

A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.

Theoretical and Experimental Analysis of an Induction Planar Actuator with Different Secondaries—A Planar Driver Application for Metallic Surface Inspection

PubMed Central

Treviso, Felipe; Silveira, Marilia A.; Flores Filho, Aly F.; Dorrell, David G.

2016-01-01

This paper presents a study on an induction planar actuator concept. The device uses the same principles as a linear induction motor in which the interaction between a travelling magnetic field and a conducting surface produces eddy currents that leads to the generation of a thrust force and can result in movement over a metallic surface. This can benefit the inspection of metallic surfaces based on the driving platform provided by the induction planar actuator. Equations of the magnetic and electric fields are presented and, by means of these equations, the forces involved were calculated. The behaviour of thrust and normal forces was analysed through the equations and by numerical models, and compared with the results obtained by measurements on a device prototype built in the laboratory as part of the study. With relation to the surface under inspection that forms the secondary, three cases were analysed: (1) a double-layered secondary formed by aluminium and ferromagnetic slabs; (2) a single aluminium layer and (3) a single ferromagnetic layer. Theoretical and measured values of thrust and normal forces showed good correlation. PMID:27007377

Sub-50-nm self-assembled nanotextures for enhanced broadband antireflection in silicon solar cells.

PubMed

Rahman, Atikur; Ashraf, Ahsan; Xin, Huolin; Tong, Xiao; Sutter, Peter; Eisaman, Matthew D; Black, Charles T

2015-01-21

Materials providing broadband light antireflection have applications as highly transparent window coatings, military camouflage, and coatings for efficiently coupling light into solar cells and out of light-emitting diodes. In this work, densely packed silicon nanotextures with feature sizes smaller than 50 nm enhance the broadband antireflection compared with that predicted by their geometry alone. A significant fraction of the nanotexture volume comprises a surface layer whose optical properties differ substantially from those of the bulk, providing the key to improved performance. The nanotexture reflectivity is quantitatively well-modelled after accounting for both its profile and changes in refractive index at the surface. We employ block copolymer self-assembly for precise and tunable nanotexture design in the range of ~10-70 nm across macroscopic solar cell areas. Implementing this efficient antireflection approach in crystalline silicon solar cells significantly betters the performance gain compared with an optimized, planar antireflection coating.

A pilot study comparing custom contoured and planar support surfaces for pressure ulcer risk over the heels for night time postural management using interface pressure mapping and discomfort scores.

PubMed

Hosking, J

2017-08-01

Custom contouring techniques are effective for reducing pressure ulcer risk in wheelchair seating. These techniques may assist the management of pressure ulcer risk during sleep for night time postural management. To investigate the effectiveness of custom contoured night time postural management components against planar support surfaces for pressure ulcer risk measures over the heels. Supine posture was captured from five healthy participants using vacuum consolidation and 3-dimensional laser scanning. Custom contoured abduction wedges were carved from polyurethane and chipped foams. Pressure mapping and the visual analog scale were used to evaluate the effectiveness of the contoured foams in reducing pressure and discomfort under the posterior heel against standard planar support surfaces. Custom contoured shapes significantly reduced interface pressures (p < 0.05) and discomfort scores (p < 0.05) when compared to planar support surfaces. Polyurethane foam was the most effective material but it did not differ significantly from chipped foam. Linear regression revealed a significant relationship between the Peak Pressure Index and discomfort scores (r = 0.997, p = 0.003). The findings of this pilot study suggested that custom contoured shapes were more effective than planar surfaces at reducing pressure ulcer risk surrogate measures over the posterior heels with polyurethane foam being the most effective material investigated. It is recommended that Evazote foam should not be used as a support surface material for night time postural management. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Liftings and stresses for planar periodic frameworks

PubMed Central

Borcea, Ciprian; Streinu, Ileana

2015-01-01

We formulate and prove a periodic analog of Maxwell’s theorem relating stressed planar frameworks and their liftings to polyhedral surfaces with spherical topology. We use our lifting theorem to prove deformation and rigidity-theoretic properties for planar periodic pseudo-triangulations, generalizing features known for their finite counterparts. These properties are then applied to questions originating in mathematical crystallography and materials science, concerning planar periodic auxetic structures and ultrarigid periodic frameworks. PMID:26973370

Method of producing an inertial sensor

NASA Technical Reports Server (NTRS)

Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor)

2008-01-01

The present invention discloses an inertial sensor comprising a planar mechanical resonator with embedded sensing and actuation for substantially in-plane vibration and having a central rigid support for the resonator. At least one excitation or torquer electrode is disposed within an interior of the resonator to excite in-plane vibration of the resonator and at least one sensing or pickoff electrode is disposed within the interior of the resonator for sensing the motion of the excited resonator. In one embodiment, the planar resonator includes a plurality of slots in an annular pattern; in another embodiment, the planar mechanical resonator comprises four masses; each embodiment having a simple degenerate pair of in-plane vibration modes.

Capacitance reduction for pillar structured devices

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

Shao, Qinghui; Conway, Adam; Nikolic, Rebecca J.

2017-05-09

In one embodiment, an apparatus includes: a first layer including a n+ dopant or p+ dopant; an intrinsic layer formed above the first layer, the intrinsic layer including a planar portion and pillars extending above the planar portion, cavity regions being defined between the pillars; and a second layer deposited on a periphery of the pillars thereby forming coated pillars, the second layer being substantially absent on the planar portion of the intrinsic layer between the coated pillars. The second layer includes an n+ dopant when the first layer includes a p+ dopant. The second layer includes a p+ dopantmore » when the first layer includes an n+ dopant. The apparatus includes a neutron sensitive material deposited between the coated pillars and above the planar portion of the intrinsic layer. In additional embodiments, an upper portion of each of the pillars includes a same type of dopant as the second layer.« less

Transparent selective illumination means suitable for use in optically activated electrical switches and optically activated electrical switches constructed using same

DOEpatents

Wilcox, R.B.

1991-09-10

A planar transparent light conducting means and an improved optically activated electrical switch made using the novel light conducting means are disclosed. The light conducting means further comprise light scattering means on one or more opposite planar surfaces thereof to transmit light from the light conducting means into adjacent media and reflective means on other surfaces of the light conducting means not containing the light scattering means. The optically activated electrical switch comprises at least two stacked photoconductive wafers, each having electrodes formed on both surfaces thereof, and separated by the planar transparent light conducting means. The light scattering means on the light conducting means face surfaces of the wafers not covered by the electrodes to transmit light from the light conducting means into the photoconductive wafers to uniformly illuminate and activate the switch. 11 figures.

Transparent selective illumination means suitable for use in optically activated electrical switches and optically activated electrical switches constructed using same

DOEpatents

Wilcox, Russell B.

1991-01-01

A planar transparent light conducting means and an improved optically activated electrical switch made using the novel light conducting means are disclosed. The light conducting means further comprise light scattering means on one or more opposite planar surfaces thereof to transmit light from the light conducting means into adjacent media and reflective means on other surfaces of the light conducting means not containing the light scattering means. The optically activated electrical switch comprises at least two stacked photoconductive wafers, each having electrodes formed on both surfaces thereof, and separated by the planar transparent light conducting means. The light scattering means on the light conducting means face surfaces of the wafers not covered by the electrodes to transmit light from the light conducting means into the photoconductive wafers to uniformly illuminate and activate the switch.

Characterizing hydrophobicity of amino acid side chains in a protein environment via measuring contact angle of a water nanodroplet on planar peptide network

PubMed Central

Zhu, Chongqin; Gao, Yurui; Li, Hui; Meng, Sheng; Li, Lei; Francisco, Joseph S.; Zeng, Xiao Cheng

2016-01-01

Hydrophobicity of macroscopic planar surface is conventionally characterized by the contact angle of water droplets. However, this engineering measurement cannot be directly extended to surfaces of proteins, due to the nanometer scale of amino acids and inherent nonplanar structures. To measure the hydrophobicity of side chains of proteins quantitatively, numerous parameters were developed to characterize behavior of hydrophobic solvation. However, consistency among these parameters is not always apparent. Herein, we demonstrate an alternative way of characterizing hydrophobicity of amino acid side chains in a protein environment by constructing a monolayer of amino acids (i.e., artificial planar peptide network) according to the primary and the β-sheet secondary structures of protein so that the conventional engineering measurement of the contact angle of a water droplet can be brought to bear. Using molecular dynamics simulations, contact angles θ of a water nanodroplet on the planar peptide network, together with excess chemical potentials of purely repulsive methane-sized Weeks−Chandler−Andersen solute, are computed. All of the 20 types of amino acids and the corresponding planar peptide networks are studied. Expectedly, all of the planar peptide networks with nonpolar amino acids are hydrophobic due to θ > 90°, whereas all of the planar peptide networks of the polar and charged amino acids are hydrophilic due to θ < 90°. Planar peptide networks of the charged amino acids exhibit complete-wetting behavior due to θ = 0°. This computational approach for characterization of hydrophobicity can be extended to artificial planar networks of other soft matter. PMID:27803319

Automated recognition of quasi-planar ignimbrite sheets and paleo-surfaces via robust segmentation of DTM - examples from the Western Cordillera of the Central Andes

NASA Astrophysics Data System (ADS)

Székely, B.; Karátson, D.; Koma, Zs.; Dorninger, P.; Wörner, G.; Brandmeier, M.; Nothegger, C.

2012-04-01

The Western slope of the Central Andes between 22° and 17°S is characterized by large, quasi-planar landforms with tilted ignimbrite surfaces and overlying younger sedimentary deposits (e.g. Nazca, Oxaya, Huaylillas ignimbrites). These surfaces were only modified by tectonic uplift and tilting of the Western Cordillera preserving minor now fossilized drainage systems. Several deep, canyons started to form from about 5 Ma ago. Due to tectonic oversteepening in a arid region of very low erosion rates, gravitational collapses and landslides additionally modified the Andean slope and valley flanks. Large areas of fossil surfaces, however, remain. The age of these surfaces has been dated between 11 Ma and 25 Ma at elevations of 3500 m in the Precordillera and at c. 1000 m near the coast. Due to their excellent preservation, our aim is to identify, delineate, and reconstruct these original ignimbrite and sediment surfaces via a sophisticated evaluation of SRTM DEMs. The technique we use here is a robust morphological segmentation method that is insensitive to a certain amount of outliers, even if they are spatially correlated. This paves the way to identify common local planar features and combine these into larger areas of a particular surface segment. Erosional dissection and faulting, tilting and folding define subdomains, and thus the original quasi-planar surfaces are modified. Additional processes may create younger surfaces, such as sedimentary floodplains and salt pans. The procedure is tuned to provide a distinction of these features. The technique is based on the evaluation of local normal vectors (perpendicular to the actual surface) that are obtained by determination of locally fitting planes. Then, this initial set of normal vectors are gradually classified into groups with similar properties providing candidate point clouds that are quasi co-planar. The quasi co-planar sets of points are analysed further against other criteria, such as number of minimum points, maximized standard deviation of spatial scatter, maximum point-to-plane surface, etc. SRTM DEMs of selected areas of the Western slope of the Central Andes have been processed with various parameter sets. The resulting domain structure shows strong correlation with tectonic features (e.g. faulting) and younger depositional surfaces whereas other segmentation features appear or disappear depending on parameters of the analysis. For example, a fine segmentation results - for a given study area - in ca. 2500 planar features (of course not all are geologically meaningful), whereas a more meaningful result has an order of magnitude less planes, ca. 270. The latter segmentation still covers the key areas, and the dissecting features (e.g., large incised canyons) are typically identified. For the fine segmentation version an area of 3863 km2 is covered by fitted planes for the ignimbrite surfaces, whereas for the more robust segmentation this area is 2555 km2. The same values for the sedimentary surfaces are 3162 km2 and 2080 km2, respectively. The total processed area was 14498 km2. As the previous numbers and the 18,1% and 18,6% decrease in the coverage suggest, the robust segmentation remains meaningful for large parts of the area while the number of planar features decreased by an order of magnitude. This result also emphasizes the importance of the initial parameters. To verify the results in more detail, residuals (difference between measured and modelled elevation) are also evaluated, and the results are fed back to the segmentation procedure. Steeper landscapes (young volcanic edifices) are clearly separated from higher-order (long-wavelength) structures. This method allows to quantitatively identify uniform surface segments and to relate these to geologically and morphologically meaningful parameters (type of depositional surface, rock type, surface age).

Snapshot gradient-recalled echo-planar images of rat brains at long echo time at 9.4 T

PubMed Central

Lei, Hongxia; Mlynárik, Vladimir; Just, Nathalie; Gruetter, Rolf

2009-01-01

With improved B0 homogeneity along with satisfactory gradient performance at high magnetic fields, snapshot gradient-recalled echo-planar imaging (GRE-EPI) would perform at long echo times (TEs) on the order of T2*, which intrinsically allows obtaining strongly T2*-weighted images with embedded substantial anatomical details in ultrashort time. The aim of this study was to investigate the feasibility and quality of long TE snapshot GRE-EPI images of rat brain at 9.4 T. When compensating for B0 inhomogeneities, especially second-order shim terms, a 200×200 μm2 in-plane resolution image was reproducibly obtained at long TE (>25 ms). The resulting coronal images at 30 ms had diminished geometric distortions and, thus, embedded substantial anatomical details. Concurrently with the very consistent stability, such GRE-EPI images should permit to resolve functional data not only with high specificity but also with substantial anatomical details, therefore allowing coregistration of the acquired functional data on the same image data set. PMID:18486393

Heterogeneous nucleation on rough surfaces: Generalized Gibbs' approach.

PubMed

Abyzov, Alexander S; Schmelzer, Jürn W P; Davydov, Leonid N

2017-12-07

Heterogeneous nucleation (condensation) of liquid droplets from vapor (gas) on a defective solid surface is considered. The vapor is described by the van der Waals equation of state. The dependence of nucleating droplet parameters on droplet size is accounted for within the generalized Gibbs approach. As a surface defect, a conic void is taken. This choice allows us to simplify the analysis and at the same time to follow the main aspects of the influence of the surface roughness on the nucleation process. Similar to condensation on ideal planar surfaces, the contact angle and catalytic factor for heterogeneous nucleation on a rough surface depend on the degree of vapor overcooling. In the case of droplet formation on a hydrophilic surface of a conic void, the nucleation rate considerably increases in comparison with the condensation on a planar interface. In fact, the presence of a defect on the hydrophilic surface leads to a considerable shift of the spinodal towards lower supersaturation in comparison with heterogeneous nucleation on a planar interface. With the decrease in the void cone angle, the heterogeneous spinodal approaches the binodal, and the region of metastability is diminished at the expense of the instability region.

Modeling of viscous damping of perforated planar microstructures. Applications in acoustics

NASA Astrophysics Data System (ADS)

Homentcovschi, Dorel; Miles, Ronald N.

2004-11-01

The paper contains an analysis of the viscous damping in perforated planar microstructures that often serve as backplates or protecting surfaces in capacitive microsensors. The focus of this work is on planar surfaces containing an offset system of periodic oval holes or its limit cases: a system of circular holes or of slits. The viscous damping is calculated as the sum of squeeze film and the holes' resistances. The optimum number of holes is determined which minimizes the total viscous damping for a given percentage of open area. Graphs and formulas are provided for designing these devices. In the case the open area is higher than 15% the numerical results show that the influence of the holes' geometry (circular or oval) has a slight influence on viscous damping. As the planar structures containing oval holes assure a better protection against dust particles and water drops, they should be preferred in designing protective surfaces for microphones working in a natural environment. The obtained results also can be applied in designing other MEMS devices that use capacitive sensing such as accelerometers, micromechanical switches, resonators, and tunable microoptical interferometers. .

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

Kutes, Yasemin; Luria, Justin; Sun, Yu

Ion beam milling is the most common modern method for preparing specific features for microscopic analysis, even though concomitant ion implantation and amorphization remain persistent challenges, particularly as they often modify materials properties of interest. Atomic force microscopy (AFM), on the other hand, can mechanically mill specific nanoscale regions in plan-view without chemical or high energy ion damage, due to its resolution, directionality, and fine load control. As an example, AFM-nanomilling (AFM-NM) is implemented for top-down planarization of polycrystalline CdTe thin film solar cells, with a resulting decrease in the root mean square (RMS) roughness by an order of magnitude,more » even better than for a low incidence FIB polished surface. Subsequently AFM-based property maps reveal a substantially stronger contrast, in this case of the short-circuit current or open circuit voltage during light exposure. Furthermore, electron back scattering diffraction (EBSD) imaging also becomes possible upon AFM-NM, enabling direct correlations between the local materials properties and the polycrystalline microstructure. Smooth shallow-angle cross-sections are demonstrated as well, based on targeted oblique milling. As expected, this reveals a gradual decrease in the average short-circuit current and maximum power as the underlying CdS and electrode layers are approached, but a relatively consistent open-circuit voltage through the diminishing thickness of the CdTe absorber. AFM-based nanomilling is therefore a powerful tool for material characterization, uniquely providing ion-damage free, selective area, planar smoothing or low-angle sectioning of specimens while preserving their functionality. This then enables novel, co-located advanced AFM measurements, EBSD analysis, and investigations by related techniques that are otherwise hindered by surface morphology or surface damage.« less

Non-planar chemical preconcentrator

DOEpatents

Manginell, Ronald P [Albuquerque, NM; Adkins, Douglas R [Albuquerque, NM; Sokolowski, Sara S [Albuquerque, NM; Lewis, Patrick R [Albuquerque, NM

2006-10-10

A non-planar chemical preconcentrator comprises a high-surface area, low mass, three-dimensional, flow-through sorption support structure that can be coated or packed with a sorptive material. The sorptive material can collect and concentrate a chemical analyte from a fluid stream and rapidly release it as a very narrow temporal plug for improved separations in a microanalytical system. The non-planar chemical preconcentrator retains most of the thermal and fabrication benefits of a planar preconcentrator, but has improved ruggedness and uptake, while reducing sorptive coating concerns and extending the range of collectible analytes.

Characterizing hydrophobicity of amino acid side chains in a protein environment via measuring contact angle of a water nanodroplet on planar peptide network.

PubMed

Zhu, Chongqin; Gao, Yurui; Li, Hui; Meng, Sheng; Li, Lei; Francisco, Joseph S; Zeng, Xiao Cheng

2016-11-15

Hydrophobicity of macroscopic planar surface is conventionally characterized by the contact angle of water droplets. However, this engineering measurement cannot be directly extended to surfaces of proteins, due to the nanometer scale of amino acids and inherent nonplanar structures. To measure the hydrophobicity of side chains of proteins quantitatively, numerous parameters were developed to characterize behavior of hydrophobic solvation. However, consistency among these parameters is not always apparent. Herein, we demonstrate an alternative way of characterizing hydrophobicity of amino acid side chains in a protein environment by constructing a monolayer of amino acids (i.e., artificial planar peptide network) according to the primary and the β-sheet secondary structures of protein so that the conventional engineering measurement of the contact angle of a water droplet can be brought to bear. Using molecular dynamics simulations, contact angles θ of a water nanodroplet on the planar peptide network, together with excess chemical potentials of purely repulsive methane-sized Weeks-Chandler-Andersen solute, are computed. All of the 20 types of amino acids and the corresponding planar peptide networks are studied. Expectedly, all of the planar peptide networks with nonpolar amino acids are hydrophobic due to θ [Formula: see text] 90°, whereas all of the planar peptide networks of the polar and charged amino acids are hydrophilic due to θ [Formula: see text] 90°. Planar peptide networks of the charged amino acids exhibit complete-wetting behavior due to θ [Formula: see text] 0°. This computational approach for characterization of hydrophobicity can be extended to artificial planar networks of other soft matter.

Simultaneous enhancement of Chlorella vulgaris growth and lipid accumulation through the synergy effect between light and nitrate in a planar waveguide flat-plate photobioreactor.

PubMed

Liao, Qiang; Sun, Yahui; Huang, Yun; Xia, Ao; Fu, Qian; Zhu, Xun

2017-11-01

Interval between adjacent planar waveguides and light intensity emitted from waveguide surface were the primary two factors affecting light distribution characteristics in the planar waveguide flat-plate photobioreactor (PW-PBR). In this paper, the synergy effect between light and nitrate in the PW-PBR was realized to simultaneously enhance microalgae growth and lipid accumulation. Under an interval of 10mm between adjacent planar waveguides, 100% of microalgae cells in regions between adjacent waveguides could be illuminated. Chlorella vulgaris growth and lipid accumulation were synchronously elevated as light intensities emitted from planar waveguide surface increasing. With an identical initial nitrate concentration of 18mM, the maximum lipid content (41.66% in dry biomass) and lipid yield (2200.25mgL -1 ) were attained under 560μmolm -2 s -1 , which were 86.82% and 133.56% higher relative to those obtained under 160μmolm -2 s -1 , respectively. The PW-PBR provides a promising way for microalgae lipid production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Active pixel sensors with substantially planarized color filtering elements

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Kemeny, Sabrina E. (Inventor)

1999-01-01

A semiconductor imaging system preferably having an active pixel sensor array compatible with a CMOS fabrication process. Color-filtering elements such as polymer filters and wavelength-converting phosphors can be integrated with the image sensor.

Generalized Models for Rock Joint Surface Shapes

PubMed Central

Du, Shigui; Hu, Yunjin; Hu, Xiaofei

2014-01-01

Generalized models of joint surface shapes are the foundation for mechanism studies on the mechanical effects of rock joint surface shapes. Based on extensive field investigations of rock joint surface shapes, generalized models for three level shapes named macroscopic outline, surface undulating shape, and microcosmic roughness were established through statistical analyses of 20,078 rock joint surface profiles. The relative amplitude of profile curves was used as a borderline for the division of different level shapes. The study results show that the macroscopic outline has three basic features such as planar, arc-shaped, and stepped; the surface undulating shape has three basic features such as planar, undulating, and stepped; and the microcosmic roughness has two basic features such as smooth and rough. PMID:25152901

Infrared evanescent field sensing with quantum cascade lasers and planar silver halide waveguides.

PubMed

Charlton, Christy; Katzir, Abraham; Mizaikoff, Boris

2005-07-15

We demonstrate the first midinfrared evanescent field absorption measurements with an InGaAs/AlInAs/InP distributed feedback (DFB) quantum cascade laser (QCL) light source operated at room temperature coupled to a free-standing, thin-film, planar, silver halide waveguide. Two different analytes, each matched to the emission frequency of a QCL, were investigated to verify the potential of this technique. The emission of a 1650 cm(-1) QCL overlaps with the amide absorption band of urea, which was deposited from methanol solution, forming urea crystals at the waveguide surface after solvent evaporation. Solid urea was detected down to 80.7 microg of precipitate at the waveguide surface. The emission frequency of a 974 cm(-1) QCL overlaps with the CH3-C absorption feature of acetic anhydride. Solutions of acetic anhydride in acetonitrile have been detected down to a volume of 0.01 microL (10.8 microg) of acetic anhydride solution after deposition at the planar waveguide (PWG) surface. Free-standing, thin-film, planar, silver halide waveguides were produced by press-tapering heated, cylindrical, silver halide fiber segments to create waveguides with a thickness of 300-190 microm, a width of 3 mm, and a length of 35 mm. In addition, Fourier transform infrared (FT-IR) evanescent field absorption measurements with planar silver halide waveguides and transmission absorption QCL measurements verify the obtained results.

Plasma processing of large curved surfaces for superconducting rf cavity modification

DOE PAGES

Upadhyay, J.; Im, Do; Popović, S.; ...

2014-12-15

In this study, plasma based surface modification of niobium is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The development of the technology based on Cl 2/Ar plasma etching has to address several crucial parameters which influence the etching rate and surface roughness, and eventually, determine cavity performance. This includes dependence of the process on the frequency of the RF generator, gas pressure, power level, the driven (inner) electrode configuration, and the chlorine concentration in the gas mixture during plasma processing. To demonstrate surface layer removal in the asymmetric non-planar geometry, we are using a simplemore » cylindrical cavity with 8 ports symmetrically distributed over the cylinder. The ports are used for diagnosing the plasma parameters and as holders for the samples to be etched. The etching rate is highly correlated with the shape of the inner electrode, radio-frequency (RF) circuit elements, chlorine concentration in the Cl 2/Ar gas mixtures, residence time of reactive species and temperature of the cavity. Using cylindrical electrodes with variable radius, large-surface ring-shaped samples and d.c. bias implementation in the external circuit we have demonstrated substantial average etching rates and outlined the possibility to optimize plasma properties with respect to maximum surface processing effect.« less

Surface tension and long range corrections of cylindrical interfaces

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

Bourasseau, E.; Malfreyt, P.; Ghoufi, A., E-mail: aziz.ghoufi@univ-rennes1.fr

2015-12-21

The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential,more » (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.« less

Negative refraction and planar focusing based on parity-time symmetric metasurfaces.

PubMed

Fleury, Romain; Sounas, Dimitrios L; Alù, Andrea

2014-07-11

We introduce a new mechanism to realize negative refraction and planar focusing using a pair of parity-time symmetric metasurfaces. In contrast to existing solutions that achieve these effects with negative-index metamaterials or phase conjugating surfaces, the proposed parity-time symmetric lens enables loss-free, all-angle negative refraction and planar focusing in free space, without relying on bulk metamaterials or nonlinear effects. This concept may represent a pivotal step towards loss-free negative refraction and highly efficient planar focusing by exploiting the largely uncharted scattering properties of parity-time symmetric systems.

Method for atmospheric pressure reactive atom plasma processing for surface modification

DOEpatents

Carr, Jeffrey W [Livermore, CA

2009-09-22

Reactive atom plasma processing can be used to shape, polish, planarize and clean the surfaces of difficult materials with minimal subsurface damage. The apparatus and methods use a plasma torch, such as a conventional ICP torch. The workpiece and plasma torch are moved with respect to each other, whether by translating and/or rotating the workpiece, the plasma, or both. The plasma discharge from the torch can be used to shape, planarize, polish, and/or clean the surface of the workpiece, as well as to thin the workpiece. The processing may cause minimal or no damage to the workpiece underneath the surface, and may involve removing material from the surface of the workpiece.

Effect of planar cuts' orientation on the perceived surface layout and object's shape.

PubMed

Bocheva, Nadejda

2009-07-01

The effect of the orientation of the cutting planes producing planar curves over the surface of an object on its perceived pose and shape was investigated for line drawings representing three-dimensional objects. The results suggest that the orientational flow produced by the surface curves introduces an apparent object rotation in depth and in the image plane and changes in its perceived elongation. The apparent location of the nearest points is determined by the points of maximal view-dependent unsigned curvature of the surface curves. The data are discussed in relation to the interaction of the shape-from-silhouette system and shape-from-contour system and its effect on the interpretation of the surface contours with respect to the surface geometry.

Heat transfer device

NASA Technical Reports Server (NTRS)

Eaton, L. R. (Inventor)

1976-01-01

An improved heat transfer device particularly suited for use as an evaporator plate in a diffusion cloud chamber. The device is characterized by a pair of mutually spaced heat transfer plates, each being of a planar configuration, having a pair of opposed surfaces defining therebetween a heat pipe chamber. Within the heat pipe chamber, in contiguous relation with the pair of opposed surfaces, there is disposed a pair of heat pipe wicks supported in a mutually spaced relationship by a foraminous spacer of a planar configuration. A wick including a foraminous layer is contiguously related to the external surfaces of the heat transfer plates for uniformly wetting these surfaces.

Biologically Complex Planar Cell Plasma Membranes Supported on Polyelectrolyte Cushions Enhance Transmembrane Protein Mobility and Retain Native Orientation.

PubMed

Liu, Han-Yuan; Chen, Wei-Liang; Ober, Christopher K; Daniel, Susan

2018-01-23

Reconstituted supported lipid bilayers (SLB) are widely used as in vitro cell-surface models because they are compatible with a variety of surface-based analytical techniques. However, one of the challenges of using SLBs as a model of the cell surface is the limited complexity in membrane composition, including the incorporation of transmembrane proteins and lipid diversity that may impact the activity of those proteins. Additionally, it is challenging to preserve the transmembrane protein native orientation, function, and mobility in SLBs. Here, we leverage the interaction between cell plasma membrane vesicles and polyelectrolyte brushes to create planar bilayers from cell plasma membrane vesicles that have budded from the cell surface. This approach promotes the direct incorporation of membrane proteins and other species into the planar bilayer without using detergent or reconstitution and preserves membrane constituents. Furthermore, the structure of the polyelectrolyte brush serves as a cushion between the planar bilayer and rigid supporting surface, limiting the interaction of the cytosolic domains of membrane proteins with this surface. Single particle tracking was used to analyze the motion of GPI-linked yellow fluorescent proteins (GPI-YFP) and neon-green fused transmembrane P2X2 receptors (P2X2-neon) and shows that this platform retains over 75% mobility of multipass transmembrane proteins in its native membrane environment. An enzyme accessibility assay confirmed that the protein orientation is preserved and results in the extracellular domain facing toward the bulk phase and the cytosolic side facing the support. Because the platform presented here retains the complexity of the cell plasma membrane and preserves protein orientation and mobility, it is a better representative mimic of native cell surfaces, which may find many applications in biological assays aimed at understanding cell membrane phenomena.

The effect of guard ring on leakage current and spectroscopic performance of TlBr planar detectors

NASA Astrophysics Data System (ADS)

Kargar, Alireza; Kim, Hadong; Cirignano, Leonard; Shah, Kanai

2014-09-01

Four thallium bromide planar detectors were fabricated from materials grown at RMD Inc. The TlBr samples were prepared to investigate the effect of guard ring on device gamma-ray spectroscopy performance, and to investigate the leakage current through surface and bulk. The devices' active area in planar configuration were 4.4 × 4.4 × 1.0 mm3. In this report, the detector fabrication process is described and the resulting energy spectra are discussed. It is shown that the guard ring improves device spectroscopic performance by shielding the sensing electrode from the surface leakage current, and by making the electric filed more uniform in the active region of the device.

POD/MAC-Based Modal Basis Selection for a Reduced Order Nonlinear Response Analysis

NASA Technical Reports Server (NTRS)

Rizzi, Stephen A.; Przekop, Adam

2007-01-01

A feasibility study was conducted to explore the applicability of a POD/MAC basis selection technique to a nonlinear structural response analysis. For the case studied the application of the POD/MAC technique resulted in a substantial improvement of the reduced order simulation when compared to a classic approach utilizing only low frequency modes present in the excitation bandwidth. Further studies are aimed to expand application of the presented technique to more complex structures including non-planar and two-dimensional configurations. For non-planar structures the separation of different displacement components may not be necessary or desirable.

Isolated resonator gyroscope with a drive and sense plate

NASA Technical Reports Server (NTRS)

Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor)

2006-01-01

The present invention discloses a resonator gyroscope comprising a vibrationally isolated resonator including a proof mass, a counterbalancing plate having an extensive planar region, and one or more flexures interconnecting the proof mass and counterbalancing plate. A baseplate is affixed to the resonator by the one or more flexures and sense and drive electrodes are affixed to the baseplate proximate to the extensive planar region of the counterbalancing plate for exciting the resonator and sensing movement of the gyroscope. The isolated resonator transfers substantially no net momentum to the baseplate when the resonator is excited.

Two-dimensional numerical simulation of boron diffusion for pyramidally textured silicon

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

Ma, Fa-Jun, E-mail: Fajun.Ma@nus.edu.sg; Duttagupta, Shubham; Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576

2014-11-14

Multidimensional numerical simulation of boron diffusion is of great relevance for the improvement of industrial n-type crystalline silicon wafer solar cells. However, surface passivation of boron diffused area is typically studied in one dimension on planar lifetime samples. This approach neglects the effects of the solar cell pyramidal texture on the boron doping process and resulting doping profile. In this work, we present a theoretical study using a two-dimensional surface morphology for pyramidally textured samples. The boron diffusivity and segregation coefficient between oxide and silicon in simulation are determined by reproducing measured one-dimensional boron depth profiles prepared using different boronmore » diffusion recipes on planar samples. The established parameters are subsequently used to simulate the boron diffusion process on textured samples. The simulated junction depth is found to agree quantitatively well with electron beam induced current measurements. Finally, chemical passivation on planar and textured samples is compared in device simulation. Particularly, a two-dimensional approach is adopted for textured samples to evaluate chemical passivation. The intrinsic emitter saturation current density, which is only related to Auger and radiative recombination, is also simulated for both planar and textured samples. The differences between planar and textured samples are discussed.« less

Novel planar field emission of ultra-thin individual carbon nanotubes.

PubMed

Song, Xuefeng; Gao, Jingyun; Fu, Qiang; Xu, Jun; Zhao, Qing; Yu, Dapeng

2009-10-07

In this work, we proposed and realized a new prototype of planar field emission device based on as-grown individual carbon nanotubes (CNTs) on the surface of a Si-SiO2 substrate. The anode, cathode and the CNT tip all lie on the same surface, so the electron emission is reduced from three-dimensional to two-dimensional. The benefits of such a design include usage of thinner CNT emitters, integrity with planar technology, stable construction, better heat dissipation, etc. A tip-to-tip field emission device was presented besides the tip-to-electrode one. Real-time, in situ observation of the planar field emission was realized in a scanning electron microscope (SEM). Measurements showed that the minimum voltage for 10 nA field emission current was only 8.0 V and the maximum emission current density in an individual CNT emitter (1.0 nm in diameter) exceeded 5.7 x 10(8) A cm(-2). These results stand out in the comparison with recent works on individual CNT field emission, indicating that the planar devices based on ultra-thin individual CNTs are more competitive candidates for next-generation electron field emitters.

A Geometric Model for Specularity Prediction on Planar Surfaces with Multiple Light Sources.

PubMed

Morgand, Alexandre; Tamaazousti, Mohamed; Bartoli, Adrien

2018-05-01

Specularities are often problematic in computer vision since they impact the dynamic range of the image intensity. A natural approach would be to predict and discard them using computer graphics models. However, these models depend on parameters which are difficult to estimate (light sources, objects' material properties and camera). We present a geometric model called JOLIMAS: JOint LIght-MAterial Specularity, which predicts the shape of specularities. JOLIMAS is reconstructed from images of specularities observed on a planar surface. It implicitly includes light and material properties, which are intrinsic to specularities. This model was motivated by the observation that specularities have a conic shape on planar surfaces. The conic shape is obtained by projecting a fixed quadric on the planar surface. JOLIMAS thus predicts the specularity using a simple geometric approach with static parameters (object material and light source shape). It is adapted to indoor light sources such as light bulbs and fluorescent lamps. The prediction has been tested on synthetic and real sequences. It works in a multi-light context by reconstructing a quadric for each light source with special cases such as lights being switched on or off. We also used specularity prediction for dynamic retexturing and obtained convincing rendering results. Further results are presented as supplementary video material, which can be found on the Computer Society Digital Library at http://doi.ieeecomputersociety.org/10.1109/TVCG.2017.2677445.

Formation of highly planarized Ni-W electrodeposits for glass imprinting mold

NASA Astrophysics Data System (ADS)

Yasui, Manabu; Kaneko, Satoru; Kurouchi, Masahito; Ito, Hiroaki; Ozawa, Takeshi; Arai, Masahiro

2017-01-01

We confirmed that increasing the total metal concentration is effective for the planarization of Ni-W films and Ni-W nanopatterns formed with a uniform height and a 480 nm pitch. At the same time, the W content in Ni-W films decreased. We investigated the relationship between the planarization of Ni-W films and the W content in Ni-W films, and confirmed that increasing the total metal concentration is effective for the inhibition of hydrogen generation. We pointed to the inhibition of hydrogen gas generation as a cause of the planarization of Ni-W films, and the reduction in the hydrogen generation amount necessary for the deposition of W as a cause of the reduction in the W content in Ni-W films. In order to obtain a flat plating film with a high W content, it is necessary to generate an adequate amount of hydrogen on the surface of the cathode and to remove hydrogen gas from the cathode surface immediately.

First-order curvature corrections to the surface tension of multicomponent systems.

PubMed

Boltachev, Grey Sh; Baidakov, Vladimir G; Schmelzer, Jürn W P

2003-08-01

The dependence of surface tension on curvature is investigated for the case of an equilibrium phase coexistence in multicomponent systems. Employing Gibbs's method of description of heterogeneous systems, an equation is derived to determine the dependence of surface tension on curvature for widely arbitrary paths of variation of the independent thermodynamic parameters. It is supposed hereby merely that the temperature is kept constant and that the variations of the different molar fractions are such that the radius of the dividing surface varies monotonically in dependence on the change of the state parameters of the ambient phase along any of the chosen paths. In the analysis, an approach developed by Blokhuis and Bedeaux for one-component systems is utilized. It relies on the expansion of the surface free energy on curvature of the dividing surface. An equation is derived that connects the first-order correction term in the expansion with the interaction potential of the particles in the multicomponent solution and with the two-particle distribution functions in the planar interfacial layer between the two phases coexisting in equilibrium at planar interfaces. The connection of the first-order curvature correction to the surface tension and the first moment of the pressure tensor at a planar interface is analyzed as well.

Mode structure of planar optical antennas on dielectric substrates

DOE PAGES

Word, Robert C.; Konenkamp, Rolf

2016-08-08

Here, we report a numerical study, supported by photoemission electron microscopy (PEEM), of sub-micron planar optical antennas on transparent substrate. We find these antennas generate intricate near-field spatial field distributions with odd and even numbers of nodes. We show that the field distributions are primarily superpositions of planar surface plasmon polariton modes confined to the metal/substrate interface. The mode structure provides opportunities for coherent switching and optical control in sub-micron volumes.

Three-dimensional curved grid finite-difference modelling for non-planar rupture dynamics

NASA Astrophysics Data System (ADS)

Zhang, Zhenguo; Zhang, Wei; Chen, Xiaofei

2014-11-01

In this study, we present a new method for simulating the 3-D dynamic rupture process occurring on a non-planar fault. The method is based on the curved-grid finite-difference method (CG-FDM) proposed by Zhang & Chen and Zhang et al. to simulate the propagation of seismic waves in media with arbitrary irregular surface topography. While keeping the advantages of conventional FDM, that is computational efficiency and easy implementation, the CG-FDM also is flexible in modelling the complex fault model by using general curvilinear grids, and thus is able to model the rupture dynamics of a fault with complex geometry, such as oblique dipping fault, non-planar fault, fault with step-over, fault branching, even if irregular topography exists. The accuracy and robustness of this new method have been validated by comparing with the previous results of Day et al., and benchmarks for rupture dynamics simulations. Finally, two simulations of rupture dynamics with complex fault geometry, that is a non-planar fault and a fault rupturing a free surface with topography, are presented. A very interesting phenomenon was observed that topography can weaken the tendency for supershear transition to occur when rupture breaks out at a free surface. Undoubtedly, this new method provides an effective, at least an alternative, tool to simulate the rupture dynamics of a complex non-planar fault, and can be applied to model the rupture dynamics of a real earthquake with complex geometry.

Use of chemical mechanical polishing in micromachining

DOEpatents

Nasby, Robert D.; Hetherington, Dale L.; Sniegowski, Jeffry J.; McWhorter, Paul J.; Apblett, Christopher A.

1998-01-01

A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface.

Contact planarization of ensemble nanowires

NASA Astrophysics Data System (ADS)

Chia, A. C. E.; LaPierre, R. R.

2011-06-01

The viability of four organic polymers (S1808, SC200, SU8 and Cyclotene) as filling materials to achieve planarization of ensemble nanowire arrays is reported. Analysis of the porosity, surface roughness and thermal stability of each filling material was performed. Sonication was used as an effective method to remove the tops of the nanowires (NWs) to achieve complete planarization. Ensemble nanowire devices were fully fabricated and I-V measurements confirmed that Cyclotene effectively planarizes the NWs while still serving the role as an insulating layer between the top and bottom contacts. These processes and analysis can be easily implemented into future characterization and fabrication of ensemble NWs for optoelectronic device applications.

Contact planarization of ensemble nanowires.

PubMed

Chia, A C E; LaPierre, R R

2011-06-17

The viability of four organic polymers (S1808, SC200, SU8 and Cyclotene) as filling materials to achieve planarization of ensemble nanowire arrays is reported. Analysis of the porosity, surface roughness and thermal stability of each filling material was performed. Sonication was used as an effective method to remove the tops of the nanowires (NWs) to achieve complete planarization. Ensemble nanowire devices were fully fabricated and I-V measurements confirmed that Cyclotene effectively planarizes the NWs while still serving the role as an insulating layer between the top and bottom contacts. These processes and analysis can be easily implemented into future characterization and fabrication of ensemble NWs for optoelectronic device applications.

Detecting Planar Surfaces in Outdoor Urban Environments

DTIC Science & Technology

2008-09-01

coplanar or parallel scene points and lines. Sturm and Maybank (18) perform 3D reconstruction given user-provided coplanarity, perpendicularity, and... Maybank , S. J. A method for intactive 3d reconstruction of piercewise planar objects from single images. in BMVC, 1999, 265–274 [19] Schaffalitzky, F

Enhanced ionic conductivity in planar sodium-β"-alumina electrolyte for electrochemical energy storage applications.

PubMed

La Rosa, Daniela; Monforte, Giuseppe; D'Urso, Claudia; Baglio, Vincenzo; Antonucci, Vincenzo; Aricò, Antonino S

2010-12-17

Solid Na-β"-Al₂O₃ electrolyte is prepared by a simple chemical route involving a pseudo-boehmite precursor and thermal treatment. Boehmite powder is used for manufacturing the planar electrolyte with appropriate bulk density after firing at 1500 °C. The structure, morphology, and surface properties of precursor powders and sintered electrolytes are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). As shown by XRD and TEM analyses, nanometer-sized particles are obtained for the boehmite precursor and a pure crystallographic phase is achieved for the sintered electrolyte. SEM analysis of the cross-section indicates good sintering characteristics. XPS shows a higher Na/Al atomic ratio on the surface for the planar electrolyte compared to a commercial tubular electrolyte (0.57 vs. 0.46). Energy-dispersive X-ray microanalysis (EDX) shows an Na/Al ratio in the bulk of 0.16, similar in the two samples. The ionic conductivity of the planar electrolyte is larger than that measured on a commercial tube of sodium-β"-alumina in a wide temperature range. At 350 °C, conductivity values of 0.5 S cm⁻¹ and 0.26 S cm⁻¹ are obtained for the planar electrolyte and the commercial tube, respectively. AC-impedance spectra show smaller grain boundary effects in the planar electrolyte than in the tubular electrolyte. These favorable properties may increase the perspectives for applying planar Na-β"-Al₂O₃ electrolytes in high-temperature batteries.

Surface Location In Scene Content Analysis

NASA Astrophysics Data System (ADS)

Hall, E. L.; Tio, J. B. K.; McPherson, C. A.; Hwang, J. J.

1981-12-01

The purpose of this paper is to describe techniques and algorithms for the location in three dimensions of planar and curved object surfaces using a computer vision approach. Stereo imaging techniques are demonstrated for planar object surface location using automatic segmentation, vertex location and relational table matching. For curved surfaces, the locations of corresponding 'points is very difficult. However, an example using a grid projection technique for the location of the surface of a curved cup is presented to illustrate a solution. This method consists of first obtaining the perspective transformation matrix from the images, then using these matrices to compute the three dimensional point locations of the grid points on the surface. These techniques may be used in object location for such applications as missile guidance, robotics, and medical diagnosis and treatment.

Development of advanced micromirror arrays by flip-chip assembly

NASA Astrophysics Data System (ADS)

Michalicek, M. Adrian; Bright, Victor M.

2001-10-01

This paper presents the design, commercial prefabrication, modeling and testing of advanced micromirror arrays fabricated using a novel, simple and inexpensive flip-chip assembly technique. Several polar piston arrays and rectangular cantilever arrays were fabricated using flip-chip assembly by which the upper layers of the array are fabricated on a separate chip and then transferred to a receiving module containing the lower layers. Typical polar piston arrays boast 98.3% active surface area, highly planarized surfaces, low address potentials compatible with CMOS electronics, highly standardized actuation between devices, and complex segmentation of mirror surfaces which allows for custom aberration configurations. Typical cantilever arrays boast large angles of rotation as well as an average surface planarity of only 1.779 nm of RMS roughness across 100 +m mirrors. Continuous torsion devices offer stable operation through as much as six degrees of rotation while binary operation devices offer stable activated positions with as much as 20 degrees of rotation. All arrays have desirable features of costly fabrication services like five structural layers and planarized mirror surfaces, but are prefabricated in the less costly MUMPs process. Models are developed for all devices and used to compare empirical data.

Fabrication of Semiordered Nanopatterned Diamond-like Carbon and Titania Films for Blood Contacting Applications.

PubMed

Nandakumar, Deepika; Bendavid, Avi; Martin, Philip J; Harris, Kenneth D; Ruys, Andrew J; Lord, Megan S

2016-03-23

Biomaterials with the ability to interface with, but not activate, blood components are essential for a multitude of medical devices. Diamond-like carbon (DLC) and titania (TiO2) have shown promise for these applications; however, both support platelet adhesion and activation. This study explored the fabrication of nanostructured DLC and TiO2 thin film coatings using a block copolymer deposition technique that produced semiordered nanopatterns with low surface roughness (5-8 nm Rrms). These surfaces supported fibrinogen and plasma protein adsorption that predominantly adsorbed between the nanofeatures and reduced the overall surface roughness. The conformation of the adsorbed fibrinogen was altered on the nanopatterned surfaces as compared with the planar surfaces to reveal higher levels of the platelet binding region. Planar DLC and TiO2 coatings supported less platelet adhesion than nanopatterned DLC and TiO2. However, platelets on the nanopatterned DLC coatings were less spread indicating a lower level of platelet activation on the nanostructured DLC coatings compared with the planar DLC coatings. These data indicated that nanostructured DLC coatings may find application in blood contacting medical devices in the future.

Numerical and experimental study of curved and planar frequency selective surfaces with arbitrary illumination. M.S. Thesis - Maryland Univ., 1989

NASA Technical Reports Server (NTRS)

Caroglanian, Armen

1991-01-01

A frequency selective surface (FSS) composed of apertures in a metallic sheet is known as the inductive FSS. The infinite inductive FSS theory is derived and the aperture fields are solved by a spectral domain formulation with method of moments solution. Both full domain and subsectional basis functions are studied. A locally planar technique (LPT) is used to determine the forward scattered field from a generally shaped inductive FSS with arbitrary illumination.

Perfluorocyclobutane containing aromatic ether polymers as planarization materials for alternative magnetic media substrates

NASA Astrophysics Data System (ADS)

Perettie, Donald J.; Judy, Jack; Chen, Qixu; Keirstead, Rick

1994-11-01

Perfluorocyclobutane aromatic ether polymers (PFCB) are being researched as planarization materials for alternative magnetic media substrates allowing smoother surfaces for lower head flying recording. The results of current work reported herein have shown that PFCB can be used to affect surfaces on canasite with R(sub A)'s less than 2 nm. In addition, magnetic media can be produced of a quality comparative to that obtained on standard NiP-coated Al as well as that produced on regular canasite with equivalent coercivities at about 1500-1600 Oe and squarenesses of 0.8 or better. In addition to the above magnetic properties the recording performance was excellent with signal-to-noise ratios of planarized media 3.5 dB higher than that on regular canasite.

NANOSTRUCTURED PLANAR WAVEGUIDE DEVICE FOR MOLECULAR IDENTIFICATION OF HAZARDOUS COMPOUNDS IN WATER BY EVANESCENT SURFACE ENHANCED RAMAN SPECTROSCOPY - PHASE I

EPA Science Inventory

Senspex, Inc. proposes to investigate a novel diagnostic tool based upon evanescent field planar waveguide sensing and complementary nanostructured mediated molecular vibration spectroscopy methods for rapid detection and analysis of hazardous biological and chemical targets i...

Light-emitting nanolattices with enhanced brightness

NASA Astrophysics Data System (ADS)

Ng, Ryan C.; Mandal, Rajib; Anthony, Rebecca J.; Greer, Julia R.

2017-02-01

Three-dimensional (3D) photonic crystals have potential in solid state lighting applications due to their advantages over conventional planar thin film devices. Periodicity in a photonic crystal structure enables engineering of the density of states to improve spontaneous light emission according to Fermi's golden rule. Unlike planar thin films, which suffer significantly from total internal reflection, a 3D architectured structure is distributed in space with many non-flat interfaces, which facilitates a substantial enhancement in light extraction. We demonstrate the fabrication of 3D nano-architectures with octahedron geometry that utilize luminescing silicon nanocrystals as active media with an aluminum cathode and indium tin oxide anode towards the realization of a 3D light emitting device. The developed fabrication procedure allows charge to pass through the nanolattice between two contacts for electroluminescence. These initial fabrication efforts suggest that 3D nano-architected devices are realizable and can reach greater efficiencies than planar devices.

The SCARLET{trademark} array for high power GEO satellites

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

Spence, B.R.; Jones, P.A.; Eskenazi, M.I.

1997-12-31

The GEO satellite market is demanding increasingly capable spacecraft which, in turn, drives commercial spacecraft manufacturers to require significantly higher power solar arrays. As satellite capability increases the demand for high power array systems which are both cost and performance competitive becomes more crucial. Conventional rigid panel planar arrays, although suitable in the past, negatively impact spacecraft competitiveness for these new applications. The Solar Concentrator Array with Refractive Linear Element Technology (SCARLET{trademark}) represents an economically attractive solution for meeting these new high power requirements. When compared to conventional planar arrays, SCARLET provides substantially lower cost and higher deployed stiffness, competitivemore » mass, better producibility, and affordable use of high efficiency multijunction cells. This paper compares cost/performance characteristics of the SCARLET array to conventional planar arrays for high power GEO spacecraft applications. High power SCARLET array configurations are described, and inherent spacecraft and array level cost/performance benefits are presented.« less

Coupling device with improved thermal interface

NASA Astrophysics Data System (ADS)

Milam, Malcolm Bruce

1992-04-01

The primary object of the present invention is to provide a simple, reliable, and lightweight coupling that will also have an efficient thermal interface. A further object of the invention is to provide a coupling that is capable of blind mating with little or no insertion forces. Another object of the invention is to provide a coupling that acts as a thermal regulator to maintain a constant temperature on one side of the coupling. Another object of the invention is to increase the available surface area of a coupling thus providing a larger area for the conduction of heat across the thermal interface. Another object of the invention is to provide a fluidic coupling that has no fluid passing across the interface, thus reducing the likelihood of leaks and contamination. The foregoing objects are achieved by utilizing, as in the prior art, a hot area (at an elevated temperature as compared to a cold area) with a need to remove excess heat from the hot area to a cold area. In this device, the thermal interface will occur not on a planar horizontal surface, but along a non-planar vertical surface, which will reduce the reaction forces and increase the thermal conductivity of the device. One non-planar surface is a surface on a cold pin extending from the cold area and the other non-planar surface is a surface on a hot pin extending from the hot area. The cold pin is fixed and does not move while the hot pin is a flexible member and its movement towards the cold pin will bring the two non-planar surfaces together forming the thermal interface. The actuating member for the device is a shape-memory actuation wire which is attached through an aperture to the hot pin and through another aperture to an actuation wire retainer. By properly programming the actuation wire, heat from the hot area will cause the actuation wire to bend the hot wire. Heat from the hot area will cause the actuation wire to bend the hot pin towards the cold pin forming the coupling and the desired thermal interface. The shape-memory actuation wire is made of a shape-memory-effect alloy such as Nitinol.

The interfacial structure of water droplets in a hydrophobic liquid

NASA Astrophysics Data System (ADS)

Smolentsev, Nikolay; Smit, Wilbert J.; Bakker, Huib J.; Roke, Sylvie

2017-05-01

Nanoscopic and microscopic water droplets and ice crystals embedded in liquid hydrophobic surroundings are key components of aerosols, rocks, oil fields and the human body. The chemical properties of such droplets critically depend on the interfacial structure of the water droplet. Here we report the surface structure of 200 nm-sized water droplets in mixtures of hydrophobic oils and surfactants as obtained from vibrational sum frequency scattering measurements. The interface of a water droplet shows significantly stronger hydrogen bonds than the air/water or hexane/water interface and previously reported planar liquid hydrophobic/water interfaces at room temperature. The observed spectral difference is similar to that of a planar air/water surface at a temperature that is ~50 K lower. Supercooling the droplets to 263 K does not change the surface structure. Below the homogeneous ice nucleation temperature, a single vibrational mode is present with a similar mean hydrogen-bond strength as for a planar ice/air interface.

Aerodynamic influence coefficient method using singularity splines

NASA Technical Reports Server (NTRS)

Mercer, J. E.; Weber, J. A.; Lesferd, E. P.

1974-01-01

A numerical lifting surface formulation, including computed results for planar wing cases is presented. This formulation, referred to as the vortex spline scheme, combines the adaptability to complex shapes offered by paneling schemes with the smoothness and accuracy of loading function methods. The formulation employes a continuous distribution of singularity strength over a set of panels on a paneled wing. The basic distributions are independent, and each satisfied all the continuity conditions required of the final solution. These distributions are overlapped both spanwise and chordwise. Boundary conditions are satisfied in a least square error sense over the surface using a finite summing technique to approximate the integral. The current formulation uses the elementary horseshoe vortex as the basic singularity and is therefore restricted to linearized potential flow. As part of the study, a non planar development was considered, but the numerical evaluation of the lifting surface concept was restricted to planar configurations. Also, a second order sideslip analysis based on an asymptotic expansion was investigated using the singularity spline formulation.

Free energy surfaces for the interaction of D-glucose with planar aromatic groups in aqueous solution

NASA Astrophysics Data System (ADS)

Wohlert, Jakob; Schnupf, Udo; Brady, John W.

2010-10-01

Multidimensional potentials of mean force for the interactions in aqueous solution of both anomers of D-glucopyranose with two planar aromatic molecules, indole and para-methyl-phenol, have been calculated using molecular dynamics simulations with umbrella sampling and were subsequently used to estimate binding free energies. Indole and para-methyl-phenol serve as models for the side chains of the amino acids tryptophan and tyrosine, respectively. In all cases, a weak affinity between the glucose molecules and the flat aromatic surfaces was found. The global minimum for these interactions was found to be for the case when the pseudoplanar face of β-D-glucopyranose is stacked against the planar surfaces of the aromatic residues. The calculated binding free energies are in good agreement with both experiment and previous simulations. The multidimensional free energy maps suggest a mechanism that could lend kinetic stability to the complexes formed by sugars bound to sugar-binding proteins.

Investigating Disk-halo Flows and Accretion: A Kinematic and Morphological Analysis of Extraplanar H I in NGC 3044 and NGC 4302

NASA Astrophysics Data System (ADS)

Zschaechner, Laura K.; Rand, Richard J.; Walterbos, Rene

2015-01-01

To further understand the origins of and physical processes operating in extra-planar gas, we present observations and kinematic models of H I in the two nearby, edge-on spiral galaxies NGC 3044 and NGC 4302. We model NGC 3044 as a single, thick disk. Substantial amounts of extra-planar H I are also detected. We detect a decrease in rotation speed with height (a lag) that shallows radially, reaching zero at approximately R 25. The large-scale kinematic asymmetry of the approaching and receding halves suggests a recent disturbance. The kinematics and morphology of NGC 4302, a Virgo Cluster member, are greatly disturbed. We model NGC 4302 as a combination of a thin disk and a second, thicker disk, the latter having a hole near the center. We detect lagging extra-planar gas, with indications of shallowing in the receding half, although its characteristics are difficult to constrain. A bridge is detected between NGC 4302 and its companion, NGC 4298. We explore trends involving the extra-planar H I kinematics of these galaxies, as well as galaxies throughout the literature, as well as possible connections between lag properties with star formation and environment. Measured lags are found to be significantly steeper than those modeled by purely ballistic effects, indicating additional factors. Radial shallowing of extra-planar lags is typical and occurs between 0.5R 25 and R 25, suggesting internal processes are important in dictating extra-planar kinematics.

Motor vehicle seat belt restraint system analysis during rollover.

PubMed

Meyer, Steven E; Hock, Davis; Forrest, Stephen; Herbst, Brian; Sances, Anthony; Kumaresan, Srirangam

2003-01-01

The multi-planar and multiple impact long duration accident sequence of a real world rollover results in multidirectional vehicle acceleration pulses and multiplanar occupant motions not typically seen in a planar crash sequence. Various researchers have documented that, while contemporary production emergency locking seatbelt retractors (ELRs) have been found to be extremely effective in the planar crashes in which they are extensively evaluated, when subjected to multi-planar acceleration environments their response may be different than expected. Specifically, accelerations in the vertical plane have been shown to substantially affect the timeliness of the retractors inertial sensor moving out of its neutral position and locking the seat belt. An analysis of the vehicle occupant motions relative to the acceleration pulses sensed at the retractor location indicates a time phase shift that, under certain circumstances, can result in unexpected seat belt spool out and occupant excursions in these multi-planar, multiple impact crash sequences. This paper will review the various previous studies focusing on the retractors response to these multidirectional, including vertical, acceleration environments and review statistical studies based upon U.S. government collected data indicating a significant difference in belt usage rates in rollover accidents as compared to all other planar accident modes. A significant number of real world accident case studies will be reviewed wherein the performance of ELR equipped seatbelt systems spooled out. Finally, the typical occupant injury and the associated mechanism due to belt spool out in real world accidents will be delineated.

Optimum Particle Size for Gold-Catalyzed CO Oxidation

PubMed Central

2018-01-01

The structure sensitivity of gold-catalyzed CO oxidation is presented by analyzing in detail the dependence of CO oxidation rate on particle size. Clusters with less than 14 gold atoms adopt a planar structure, whereas larger ones adopt a three-dimensional structure. The CO and O2 adsorption properties depend strongly on particle structure and size. All of the reaction barriers relevant to CO oxidation display linear scaling relationships with CO and O2 binding strengths as main reactivity descriptors. Planar and three-dimensional gold clusters exhibit different linear scaling relationship due to different surface topologies and different coordination numbers of the surface atoms. On the basis of these linear scaling relationships, first-principles microkinetics simulations were conducted to determine CO oxidation rates and possible rate-determining step of Au particles. Planar Au9 and three-dimensional Au79 clusters present the highest CO oxidation rates for planar and three-dimensional clusters, respectively. The planar Au9 cluster is much more active than the optimum Au79 cluster. A common feature of optimum CO oxidation performance is the intermediate binding strengths of CO and O2, resulting in intermediate coverages of CO, O2, and O. Both these optimum particles present lower performance than maximum Sabatier performance, indicating that there is sufficient room for improvement of gold catalysts for CO oxidation. PMID:29707098

Biomimetic surface patterning for long-term transmembrane access

PubMed Central

VanDersarl, Jules J.; Renaud, Philippe

2016-01-01

Here we present a planar patch clamp chip based on biomimetic cell membrane fusion. This architecture uses nanometer length-scale surface patterning to replicate the structure and function of membrane proteins, creating a gigaohm seal between the cell and a planar electrode array. The seal is generated passively during cell spreading, without the application of a vacuum to the cell surface. This interface can enable cell-attached and whole-cell recordings that are stable to 72 hours, and generates no visible damage to the cell. The electrodes can be very small (<5 μm) and closely packed, offering a high density platform for cellular measurement. PMID:27577519

Biomimetic surface patterning for long-term transmembrane access.

PubMed

VanDersarl, Jules J; Renaud, Philippe

2016-08-31

Here we present a planar patch clamp chip based on biomimetic cell membrane fusion. This architecture uses nanometer length-scale surface patterning to replicate the structure and function of membrane proteins, creating a gigaohm seal between the cell and a planar electrode array. The seal is generated passively during cell spreading, without the application of a vacuum to the cell surface. This interface can enable cell-attached and whole-cell recordings that are stable to 72 hours, and generates no visible damage to the cell. The electrodes can be very small (<5 μm) and closely packed, offering a high density platform for cellular measurement.

Use of chemical mechanical polishing in micromachining

DOEpatents

Nasby, R.D.; Hetherington, D.L.; Sniegowski, J.J.; McWhorter, P.J.; Apblett, C.A.

1998-09-08

A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface. 4 figs.

Terahertz plasmonic Bessel beamformer

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

Monnai, Yasuaki; Shinoda, Hiroyuki; Jahn, David

We experimentally demonstrate terahertz Bessel beamforming based on the concept of plasmonics. The proposed planar structure is made of concentric metallic grooves with a subwavelength spacing that couple to a point source to create tightly confined surface waves or spoof surface plasmon polaritons. Concentric scatterers periodically incorporated at a wavelength scale allow for launching the surface waves into free space to define a Bessel beam. The Bessel beam defined at 0.29 THz has been characterized through terahertz time-domain spectroscopy. This approach is capable of generating Bessel beams with planar structures as opposed to bulky axicon lenses and can be readily integratedmore » with solid-state terahertz sources.« less

Interaction of acoustic levitation field with liquid reflecting surface

NASA Astrophysics Data System (ADS)

Hong, Z. Y.; Xie, W. J.; Wei, B.

2010-01-01

Single-axis acoustic levitation of substances, such as foam, water, polymer, and aluminum, is achieved by employing various liquids as the sound reflectors. The interaction of acoustic levitation field with liquid reflecting surface is investigated theoretically by considering the deformation of the liquid surface under acoustic radiation pressure. Numerical calculations indicate that the deformation degree of the reflecting surface shows a direct proportion to the acoustic radiation power. Appropriate deformation is beneficial whereas excessive deformation is unfavorable to enhance the levitation capability. Typically, the levitation capability with water reflector is smaller than that with the concave rigid reflector but slightly larger than that with the planar rigid reflector at low emitter vibration intensity. Liquid reflectors with larger surface tension and higher density behave more closely to the planar rigid reflector.

Perpendicular Growth Characteristics of Cu-Sn Intermetallic Compounds at the Surface of 99Sn-1Cu/Cu Solder Interconnects

NASA Astrophysics Data System (ADS)

Chen, Zhiwen; Liu, Changqing; Wu, Yiping; An, Bing

2015-12-01

The growth of intermetallic compounds (IMCs) on the free surface of 99Sn-1Cu solder joints perpendicular to the interdiffusion direction has been investigated in this work. The specimens were specifically designed and polished to reveal a flat free surface at the solder/Cu interface for investigation. After aging at 175°C for progressively increased durations, the height of the perpendicular IMCs was examined and found to follow a parabolic law with aging duration that could be expressed as y = 0.11√ t, where t is the aging duration in hours and y is the height of the perpendicular IMCs in μm. For comparison, the planar growth of IMCs along the interdiffusion direction was also investigated in 99Sn-1Cu/Cu solder joints. After prolonged aging at 175°C, the thickness of the planar interfacial IMC layers also increased parabolically with aging duration and could be expressed as h_{{IMC}} = 0.27√ t + 4.6, where h is the thickness in μm and t is the time in hours. It was found that both the planar and perpendicular growth of the IMCs were diffusion-controlled processes, but the perpendicular growth of the IMCs was much slower than their planar growth due to the longer diffusion distance. It is proposed that Cu3Sn forms prior to the formation of Cu6Sn5 in the perpendicular IMCs, being the reverse order compared with the planar IMC growth.

The structure of the NO(X (2)Pi)-N(2) complex: A joint experimental-theoretical study.

PubMed

Wen, B; Meyer, H; Kłos, J

2010-04-21

We report the first measurement of the spectrum of the NO-N(2) complex in the region of the first vibrational NO overtone transition. The origin band of the complex is blueshifted by 0.30 cm(-1) from the corresponding NO monomer frequency. The observed spectrum consists of three bands assigned to the origin band, the excitation of one quantum of z-axis rotation and one associated hot band. The spacing of the bands and the rotational structure indicate a T-shaped vibrationally averaged structure with the NO molecule forming the top of the T. These findings are confirmed by high level ab initio calculations of the potential energy surfaces in planar symmetry. The deepest minimum is found for a T-shaped geometry on the A(")-surface. As a result the sum potential also has the global minimum for this structure. The different potential surfaces show several additional local minima at slightly higher energies indicating that the complex most likely will perform large amplitude motion even in its ground vibrational state. Nevertheless, as suggested by the measured spectra, the complex must, on average, spend a substantial amount of time near the T-shaped configuration.

Sorption of Sr, Co and Zn on illite: Batch experiments and modelling including Co in-diffusion measurements on compacted samples

NASA Astrophysics Data System (ADS)

Montoya, V.; Baeyens, B.; Glaus, M. A.; Kupcik, T.; Marques Fernandes, M.; Van Laer, L.; Bruggeman, C.; Maes, N.; Schäfer, T.

2018-02-01

Experimental investigations on the uptake of divalent cations (Sr, Co and Zn) onto illite (Illite du Puy, Le-Puy-en-Velay, France) were carried out by three different international research groups (Institute for Nuclear Waste Disposal, KIT (Germany), Group Waste & Disposal, SCK-CEN, (Belgium) and Laboratory for Waste Management, PSI (Switzerland)) in the framework of the European FP7 CatClay project. The dependence of solid-liquid distribution ratios (Rd values) on pH at trace metal conditions (sorption edges) and on the metal ion concentration (sorption isotherms) was determined in dilute suspensions of homo-ionic Na-illite (Na-IdP) under controlled N2 atmosphere. The experimental results were modelled using the 2 Site Protolysis Non Electrostatic Surface Complexation and Cation Exchange (2SPNE SC/CE) sorption model. The sorption of Sr depends strongly on ionic strength, while a rather weak pH dependence is observed in a pH range between 3 and 11. The data were modelled with cation exchange reactions, taking into account competition with H, K, Ca, Mg and Al, and surface complexation on weak amphotheric edge sites at higher pH values. The sorption of Co on Na-IdP, however, is strongly pH dependent. Cation exchange on the planar sites and surface complexation on strong and weak amphoteric edge sites were used to describe the Co sorption data. Rd values for Co derived from in-diffusion measurements on compacted Na-IdP samples (bulk-dry density of 1700 kg m-3) between pH 5.0 and 9.0 are in good agreement with the batch sorption data. The equivalence of both approaches to measure sorption was thus confirmed for the present test system. In addition, the results highlight the importance of both major and minor surface species for the diffusive transport behaviour of strongly sorbing metal cations. While surface complexes at the edge sites determine largely the Rd value, the diffusive flux may be governed by those species bound to the planar sites, even at low fractional occupancies. The pH dependent sorption determined for trace Zn concentrations showed large Rd values across the entire pH range with almost no dependence on the background electrolyte concentration. Additional sorption experiments carried out at substantial fractional Zn loadings demonstrated that the selectivity for the exchange of Na+ for Zn2+ at the planar sites could not explain the large Rd values measured at low pH and trace Zn concentrations. This suggests that another mechanism is ruling Zn uptake under these conditions.

Direct Visualization of Planar Assembly of Plasmonic Nanoparticles Adjacent to Electrodes in Oscillatory Electric Fields.

PubMed

Ferrick, Adam; Wang, Mei; Woehl, Taylor J

2018-05-29

Electric field-directed assembly of colloidal nanoparticles (NPs) has been widely adopted for fabricating functional thin films and nanostructured surfaces. While first-order electrokinetic effects on NPs are well-understood in terms of classical models, effects of second-order electrokinetics that involve induced surface charge are still poorly understood. Induced charge electroosmotic phenomena, such as electrohydrodynamic (EHD) flow, have long been implicated in electric field-directed NP assembly with little experimental basis. Here, we use in situ dark-field optical microscopy and plasmonic NPs to directly observe the dynamics of planar assembly of colloidal NPs adjacent to a planar electrode in low-frequency (<1 kHz) oscillatory electric fields. We exploit the change in plasmonic NP color resulting from interparticle plasmonic coupling to visualize the assembly dynamics and assembly structure of silver NPs. Planar assembly of NPs is unexpected because of strong electrostatic repulsion between NPs and indicates that there are strong attractive interparticle forces oriented perpendicular to the electric field direction. A parametric investigation of the voltage- and frequency-dependent phase behavior reveals that planar NP assembly occurs over a narrow frequency range below which irreversible ballistic deposition occurs. Two key experimental observations are consistent with EHD flow-induced NP assembly: (1) NPs remain mobile during assembly and (2) electron microscopy observations reveal randomly close-packed planar assemblies, consistent with strong interparticle attraction. We interpret planar assembly in terms of EHD fluid flow and develop a scaling model that qualitatively agrees with the measured phase regions. Our results are the first direct in situ observations of EHD flow-induced NP assembly and shed light on long-standing unresolved questions concerning the formation of NP superlattices during electric field-induced NP deposition.

Symmetry breaking in tensor models

NASA Astrophysics Data System (ADS)

Benedetti, Dario; Gurau, Razvan

2015-11-01

In this paper we analyze a quartic tensor model with one interaction for a tensor of arbitrary rank. This model has a critical point where a continuous limit of infinitely refined random geometries is reached. We show that the critical point corresponds to a phase transition in the tensor model associated to a breaking of the unitary symmetry. We analyze the model in the two phases and prove that, in a double scaling limit, the symmetric phase corresponds to a theory of infinitely refined random surfaces, while the broken phase corresponds to a theory of infinitely refined random nodal surfaces. At leading order in the double scaling limit planar surfaces dominate in the symmetric phase, and planar nodal surfaces dominate in the broken phase.

Silver nanoparticles with planar twinned defects: effect of halides for precise tuning of plasmon resonance maxima from 400 to >900 nm.

PubMed

Cathcart, Nicole; Frank, Andrew J; Kitaev, Vladimir

2009-12-14

We studied effects of halides on morphology of planar twinned silver nanoparticles and demonstrated application of these effects to precisely tune silver surface plasmon resonance maxima in a broad vis-NIR range using a reliable two-stage modification protocol.

Micromolded PDMS planar electrode allows patch clamp electrical recordings from cells.

PubMed

Klemic, Kathryn G; Klemic, James F; Reed, Mark A; Sigworth, Fred J

2002-06-01

The patch clamp method measures membrane currents at very high resolution when a high-resistance 'gigaseal' is established between the glass microelectrode and the cell membrane (Pflugers Arch. 391 (1981) 85; Neuron 8 (1992) 605). Here we describe the first use of the silicone elastomer, poly(dimethylsiloxane) (PDMS), for patch clamp electrodes. PDMS is an attractive material for patch clamp recordings. It has low dielectric loss and can be micromolded (Annu. Rev. Mat. Sci. 28 (1998) 153) into a shape that mimics the tip of the glass micropipette. Also, the surface chemistry of PDMS may be altered to mimic the hydrophilic nature of glass (J. Appl. Polym. Sci. 14 (1970) 2499; Annu. Rev. Mat. Sci. 28 (1998) 153), thereby allowing a high-resistance seal to a cell membrane. We present a planar electrode geometry consisting of a PDMS partition with a small aperture sealed between electrode and bath chambers. We demonstrate that a planar PDMS patch electrode, after oxidation of the elastomeric surface, permits patch clamp recording on Xenopus oocytes. Our results indicate the potential for high-throughput patch clamp recording with a planar array of PDMS electrodes.

FIBER AND INTEGRATED OPTICS: Reflection of electromagnetic radiation from a multilayer waveguide structure with an absorbing metal layer

NASA Astrophysics Data System (ADS)

Chernushich, A. P.; Shkerdin, G. N.; Shukin, Yu M.

1992-10-01

The angular distribution of the reflection coefficient of an asymmetric multilayer planar structure containing a thin metal film and a planar optical waveguide has been found by accurate numerical calculations. There are resonances in the reflection coefficient associated with hybrid modes of the structure. The cases of strong and weak coupling of the surface polariton modes with the waveguide modes are discussed. The results of the numerical analysis agree with solutions of Maxwell's equations for a multilayer planar structure.

Background Oriented Schlieren Implementation in a Jet-Surface Interaction Test

NASA Technical Reports Server (NTRS)

Clem, Michelle M.; Brown, Clifford A.; Fagan, Amy

2013-01-01

Many current and future aircraft designs rely on the wing or other aircraft surfaces to shield the engine noise from observers on the ground. However the available data regarding how a planar surface interacts with a jet to shield and/or enhance the jet noise are currently limited. Therefore, the Jet-Surface Interaction Tests supported by NASA's Fundamental Aeronautics Program's Fixed Wing Project were undertaken to supply experimental data covering a wide range of surface geometries and positions interacting with high-speed jet flows in order to support the development of noise prediction methods. Phase 1 of the Test was conducted in the Aero-Acoustic Propulsion Laboratory at NASA Glenn Research Center and consisted of validating noise prediction schemes for a round nozzle interacting with a planar surface. Phased array data and far-field acoustic data were collected for both the shielded and reflected sides of the surface. Phase 1 results showed that the broadband shock noise was greatly reduced by the surface when the jet was operated at the over-expanded condition, however, it was unclear whether this reduction was due a change in the shock cell structure by the surface. In the present study, Background Oriented Schlieren is implemented in Phase 2 of the Jet-Surface Interaction Tests to investigate whether the planar surface interacts with the high-speed jet ow to change the shock cell structure. Background Oriented Schlieren data are acquired for under-expanded, ideally-expanded, and over-expanded ow regimes for multiple axial and radial positions of the surface at three different plate lengths. These data are analyzed with far-field noise measurements to relate the shock cell structure to the broadband shock noise produced by a jet near a surface.

Solar module having reflector between cells

DOEpatents

Kardauskas, Michael J.

1999-01-01

A photovoltaic module comprising an array of electrically interconnected photovoltaic cells disposed in a planar and mutually spaced relationship between a light-transparent front cover member in sheet form and a back sheet structure is provided with a novel light-reflecting means disposed between adjacent cells for reflecting light falling in the areas between cells back toward said transparent cover member for further internal reflection onto the solar cells. The light-reflecting comprises a flexible plastic film that has been embossed so as to have a plurality of small V-shaped grooves in its front surface, and a thin light-reflecting coating on said front surface, the portions of said coating along the sides of said grooves forming light-reflecting facets, said grooves being formed so that said facets will reflect light impinging thereon back into said transparent cover sheet with an angle of incidence greater than the critical angle, whereby substantially all of the reflected light will be internally reflected from said cover sheet back to said solar modules, thereby increasing the current output of the module.

Fundamental and practical limits of planar tracking solar concentrators.

PubMed

Grede, Alex J; Price, Jared S; Giebink, Noel C

2016-12-26

Planar microtracking provides an alternate paradigm for solar concentration that offers the possibility of realizing high-efficiency embedded concentrating photovoltaic systems in the form factor of standard photovoltaic panels. Here, we investigate the thermodynamic limit of planar tracking optical concentrators and establish that they can, in principal, achieve the sine limit of their orientationally-tracked counterparts provided that the receiver translates a minimum distance set by the field of view half-angle. We develop a phase space methodology to optimize practical planar tracking concentrators and apply it to the design of a two surface, catadioptric system that operates with > 90% optical efficiency over a 140° field of view at geometric gains exceeding 1000×. These results provide a reference point for subsequent developments in the field and indicate that planar microtracking can achieve the high optical concentration ratio required in commercial concentrating photovoltaic systems.

Non-planar microfabricated gas chromatography column

DOEpatents

Lewis, Patrick R.; Wheeler, David R.

2007-09-25

A non-planar microfabricated gas chromatography column comprises a planar substrate having a plurality of through holes, a top lid and a bottom lid bonded to opposite surfaces of the planar substrate, and inlet and outlet ports for injection of a sample gas and elution of separated analytes. A plurality of such planar substrates can be aligned and stacked to provide a longer column length having a small footprint. Furthermore, two or more separate channels can enable multi-channel or multi-dimensional gas chromatography. The through holes preferably have a circular cross section and can be coated with a stationary phase material or packed with a porous packing material. Importantly, uniform stationary phase coatings can be obtained and band broadening can be minimized with the circular channels. A heating or cooling element can be disposed on at least one of the lids to enable temperature programming of the column.

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

Zhuang, Jinda; Ju, Y. Sungtaek, E-mail: just@seas.ucla.edu

One major challenge in incorporating flexible electronics or optoelectronics on curved surfaces is the requirement of significant stretchability. We report a tunable platform for incorporating flexible and yet non-stretching device layers on a hemisphere. In this configuration, an array of planar petals contractively maps onto the surface of an inflatable hemisphere through elastocapillary interactions mediated by an interface liquid. A mechanical model is developed to elucidate the dependence of the conformality of the petal structures on their elastic modulus and thickness and the liquid surface tension. The modeling results are validated against experimental results obtained using petal structures of differentmore » thicknesses, restoring elastic spring elements of different spring constants, and liquids with different surface tension coefficients. Our platform will enable facile integration of non-stretching electronic and optoelectronic components prepared using established planar fabrication techniques on tunable hemispherical surfaces.« less

Summary on several key techniques in 3D geological modeling.

PubMed

Mei, Gang

2014-01-01

Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized.

Cascaded exciton energy transfer in a monolayer semiconductor lateral heterostructure assisted by surface plasmon polariton.

PubMed

Shi, Jinwei; Lin, Meng-Hsien; Chen, I-Tung; Mohammadi Estakhri, Nasim; Zhang, Xin-Quan; Wang, Yanrong; Chen, Hung-Ying; Chen, Chun-An; Shih, Chih-Kang; Alù, Andrea; Li, Xiaoqin; Lee, Yi-Hsien; Gwo, Shangjr

2017-06-26

Atomically thin lateral heterostructures based on transition metal dichalcogenides have recently been demonstrated. In monolayer transition metal dichalcogenides, exciton energy transfer is typically limited to a short range (~1 μm), and additional losses may be incurred at the interfacial regions of a lateral heterostructure. To overcome these challenges, here we experimentally implement a planar metal-oxide-semiconductor structure by placing a WS 2 /MoS 2 monolayer heterostructure on top of an Al 2 O 3 -capped Ag single-crystalline plate. We find that the exciton energy transfer range can be extended to tens of microns in the hybrid structure mediated by an exciton-surface plasmon polariton-exciton conversion mechanism, allowing cascaded exciton energy transfer from one transition metal dichalcogenides region supporting high-energy exciton resonance to a different transition metal dichalcogenides region in the lateral heterostructure with low-energy exciton resonance. The realized planar hybrid structure combines two-dimensional light-emitting materials with planar plasmonic waveguides and offers great potential for developing integrated photonic and plasmonic devices.Exciton energy transfer in monolayer transition metal dichalcogenides is limited to short distances. Here, Shi et al. fabricate a planar metal-oxide-semiconductor structure and show that exciton energy transfer can be extended to tens of microns, mediated by an exciton-surface-plasmon-polariton-exciton conversion mechanism.

Constrained Quantum Mechanics: Chaos in Non-Planar Billiards

ERIC Educational Resources Information Center

Salazar, R.; Tellez, G.

2012-01-01

We illustrate some of the techniques to identify chaos signatures at the quantum level using as guiding examples some systems where a particle is constrained to move on a radial symmetric, but non-planar, surface. In particular, two systems are studied: the case of a cone with an arbitrary contour or "dunce hat billiard" and the rectangular…

Dynamics of collision of a vortex ring and a planar surface

NASA Astrophysics Data System (ADS)

McErlean, Michael; Krane, Michael; Fontaine, Arnold

2009-11-01

The dynamics of the impact between a vortex ring and a planar surface orientated perpendicular to the direction of travel are presented. High Reynolds number vortex rings are injected into a quiescent tank of water using a piston-cylinder generator before colliding with a target at a long distance. Both the pressure at the stagnation point on the surface and the force imparted to the target by the ring impact are measured directly. The changes in both are related to the ring motion and deformation captured by high speed digital video, and DPIV measurements. These relations are used to develop a scaling law relation between impact force and vortex ring circulation, speed, and size.

Matrix-assisted energy conversion in nanostructured piezoelectric arrays

DOEpatents

Sirbuly, Donald J.; Wang, Xianying; Wang, Yinmin

2013-01-01

A nanoconverter is capable of directly generating electricity through a nanostructure embedded in a polymer layer experiencing differential thermal expansion in a stress transfer zone. High surface-to-volume ratio semiconductor nanowires or nanotubes (such as ZnO, silicon, carbon, etc.) are grown either aligned or substantially vertically aligned on a substrate. The resulting nanoforest is then embedded with the polymer layer, which transfers stress to the nanostructures in the stress transfer zone, thereby creating a nanostructure voltage output due to the piezoelectric effect acting on the nanostructure. Electrodes attached at both ends of the nanostructures generate output power at densities of .about.20 nW/cm.sup.2 with heating temperatures of .about.65.degree. C. Nanoconverters arrayed in a series parallel arrangement may be constructed in planar, stacked, or rolled arrays to supply power to nano- and micro-devices without use of external batteries.

Free energy surface of two- and three-dimensional transitions of Au 12 nanoclusters obtained by ab initio metadynamics

NASA Astrophysics Data System (ADS)

Santarossa, Gianluca; Vargas, Angelo; Iannuzzi, Marcella; Baiker, Alfons

2010-05-01

The description of the conformational space generated by metal nanoparticles is a fundamental issue for the study of their physicochemical properties. In this investigation, an exhaustive exploration and a unified view of the conformational space of a gold nanocluster is provided using a Au 12 cluster as an example. Such system is characterized by coexisting planar/quasiplanar and tridimensional conformations separated by high-energy barriers. The conformational space of Au 12 has been explored by means of Born-Oppenheimer ab initio metadynamics, i.e., a molecular dynamics simulation coupled with a history dependent potential to accelerate events that might occur on a long time scale compared to the time step used in the simulations (rare events). The sampled conformations have complex, in general not intuitive topologies that we have classified as planar/quasiplanar or tridimensional, belonging to different regions of the free energy surface. Three conformational free energy basins were identified, one for the planar/quasiplanar and two for the tridimensional structures. At thermodynamic equilibrium, the planar/quasi-planar and tridimensional conformations were found to coexist, to be fluxional and to be separated by high-free-energy barriers. The comparison between the free energy and the potential energy revealed the relevance of the entropic contribution in the equilibrium distribution of the conformations of the cluster.

Rotation flexure with temperature controlled modal frequency

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

Salas, Theodore E.; Barney, Patrick S.; Ison, Aaron M.

A flexure bearing includes an inner race, an outer race, and a plurality of substantially planar radially extending blades coupled between the inner and outer race. The blades have a thickness that is thinner than a thickness of the inner and outer races. The inner race, outer race, and blades have substantially the same height. At least one heating element is coupled to the inner race and/or the outer race. The heating element is configured to apply heat to the race that it is coupled to in order to tune the flexure bearing.

A field-cancellation algorithm for constructing economical planar permanent magnet (PM) multipoles with large high-quality field apertures

NASA Astrophysics Data System (ADS)

Tatchyn, Roman

1997-05-01

In recent years studies have been initiated on a new class of multipole field generators consisting of cuboid planar permanent magnet (PM) pieces arranged in bi-planar arrays of 2-fold rotational symmetry(R. Tatchyn, "Planar Permanent Magnet Multipoles: for Particle Accelerator and Storage Ring Applications ," IEEE Trans. Mag. 30, 5050(1994).)(T. Cremer, R. Tatchyn, "Planar Permanent Magnet Multipoles: Measurements and Configurations," in Proceedings of the 1995 Particle Accelerator Conference, IEEE Catalog No. 95CH35843, paper FAQ-20.). These structures, first introduced for Free Electron Laser (FEL) applications(R. Tatchyn, "Selected applications of planar permanent magnet multipoles in FEL insertion device design," NIM A341, 449(1994).), are based on reducing the rotational symmetry of conventional N-pole field generators from N-fold to 2-fold. One consequence of this reduction is a large higher-multipole content in a planar PM multipole's field at distances relatively close to the structure's axis, making it generally unsuitable for applications requiring a large high-quality field aperture. In this paper we outline an economical field-cancellation algorithm that can substantially decrease the harmonic content of a planar PM's field without breaking its biplanar geometry or 2-fold rotational symmetry. This will enable planar PM multipoles to be employed in a broader range of applications than heretofore possible, in particular as distributed focusing elements installed in insertion device gaps on synchrotron storage rings. This accomplishment is expected to remove the conventional restriction of an insertion device's length to the scale of the local focusing beta, enabling short-period, small-gap undulators to be installed and operated as high-brightness sources on lower-energy storage rings(R. Tatchyn, P. Csonka, A. Toor, "Perspectives on micropole undulators in synchrotron radiation technology," Rev. Sci. Instrum. 60(7), 1796(1989).). Operation as ordinary focusing elements in storage ring magnetic lattices, as well as the performance of other high-quality multipole applications, should also becomes possible with the realization of the proposed structures.

Holding characteristics of planar objects suspended by near-field acoustic levitation

PubMed

Matsuo; Koike; Nakamura; Ueha; Hashimoto

2000-03-01

The authors have found the acoustic levitation phenomenon where planar objects of 10 kg weight can be levitated near a vibration surface. This phenomenon has been studied for non-contact transportation. A circular planar object can be suspended without contacting a circular vibration plate. We have studied the holding force which acts horizontally on the levitated objects. The horizontal position of the object is stabilized by this force. In this paper, we discuss the effect of the radius of a levitated object, levitation distance, displacement amplitude of the vibration plate and the vibration mode on the suspending force.

Hooked differential mobility spectrometry apparatus and method therefore

DOEpatents

Shvartsburg, Alexandre A [Richland, WA; Tang, Keqi [Richland, WA; Ibrahim, Yehia M [Richland, WA; Smith, Richard D [Richland, WA

2009-02-17

Disclosed are a device and method for improved interfacing of differential mobility spectrometry (DMS) or field asymmetric waveform ion mobility spectrometry (FAIMS) analyzers of substantially planar geometry to subsequent or preceding instrument stages. Interfacing is achieved using curved DMS elements, where a thick ion beam emitted by planar DMS analyzers or injected into them for ion filtering is compressed to the gap median by DMS ion focusing effect in a spatially inhomogeneous electric field. Resulting thinner beams are more effectively transmitted through necessarily constrained conductance limit apertures to subsequent instrument stages operated at a pressure lower than DMS, and/or more effectively injected into planar DMS analyzers. The technology is synergetic with slit apertures, slit aperture/ion funnels, and high-pressure ion funnel interfaces known in the art which allow for increasing cross-sectional area of MS inlets. The invention may be used in integrated analytical platforms, including, e.g., DMS/MS, LC/DMS/MS, and DMS/IMS/MS that could replace and/or enhance current LC/MS methods, e.g., for proteomics research.

Physical Characterization of Cu-Ni-P Thin Films aiming at Cu/Cu-Ni-P Thermocouples

NASA Astrophysics Data System (ADS)

Tomachevski, F.; Sparvoli, M.; dos Santos Filho, S. G.

2015-03-01

Cu-Ni-P thin films have a high-thermoelectric power, which allows the fabrication of very sensitive heat-flux sensors based on planar technology. In this work, (100) silicon surfaces were pre-activated in a diluted hydrofluoric acid solution containing PdCl2. Following, Cu-Ni-P thin films were chemically deposited using an alkaline chemical bath containing 15 g/l NiSO4.6H2O; 0.2 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O and 60 g/l Na3C6H5O7.2H2O at temperature of 80 °C where NH4OH was added until pH was 8.0. It was noteworthy that the stoichiometric percentages of Ni and Cu vary substantially for immersion times in the range of 1 to 3 min and they become almost stable at 50% and 35%, respectively, when the immersion time is higher than 3 min. In addition, the percentage of P remains almost constant around 1718 % for all the immersion times studied. On the other hand, the sheet resistance also varies substantially for immersion times in the range of 1 to 3 min. Based on the surface morphology, smaller grains with size in the range of 0.02 to 0.1 μm are initially grown on the silicon surface and exposed regions of silicon without deposits are also observed for immersion times in the range of 1 to 3min. Therefore, the discontinuities and non uniformities of the films are promoting, respectively, the observed behaviours of sheet resistance and stoichiometry.

Application of the Quadrupole Method for Simulation of Passive Thermography

NASA Technical Reports Server (NTRS)

Winfree, William P.; Zalameda, Joseph N.; Gregory, Elizabeth D.

2017-01-01

Passive thermography has been shown to be an effective method for in-situ and real time nondestructive evaluation (NDE) to measure damage growth in a composite structure during cyclic loading. The heat generation by subsurface flaw results in a measurable thermal profile at the surface. This paper models the heat generation as a planar subsurface source and calculates the resultant temperature profile at the surface using a three dimensional quadrupole. The results of the model are compared to finite element simulations of the same planar sources and experimental data acquired during cyclic loading of composite specimens.

Effects of alignment layer thickness on the pretilt angle of liquid crystals

NASA Astrophysics Data System (ADS)

Son, Jong-Ho; Zin, Wang-Cheol

2010-12-01

Mixture solutions of vertical- and planar-aligning polyimide precursors were coated on bare glass. The concentrations of the solutions were varied to control the thicknesses of the films. The resulting blend films were baked to induce imidization and then rubbed. The thicknesses (t) of the blend film and of the pure vertical-alignment film affected their surface energies; the pretilt angle can be fully controlled in the range 5.5°≤Θ0≤87° by adjusting t. The surface energy of pure planar-alignment layers was independent of t.

Strongly Confined Spoof Surface Plasmon Polaritons Waveguiding Enabled by Planar Staggered Plasmonic Waveguides

NASA Astrophysics Data System (ADS)

Ye, Longfang; Xiao, Yifan; Liu, Yanhui; Zhang, Liang; Cai, Guoxiong; Liu, Qing Huo

2016-12-01

We demonstrate a novel route to achieving highly efficient and strongly confined spoof surface plasmon polaritons (SPPs) waveguides at subwavelength scale enabled by planar staggered plasmonic waveguides (PSPWs). The structure of these new waveguides consists of an ultrathin metallic strip with periodic subwavelength staggered double groove arrays supported by a flexible dielectric substrate, leading to unique staggered EM coupling and waveguiding phenomenon. The spoof SPP propagation properties, including dispersion relations and near field distributions, are numerically investigated. Furthermore, broadband coplanar waveguide (CPW) to planar staggered plasmonic waveguide (PSPW) transitions are designed to achieve smooth momentum matching and highly efficient spoof SPP mode conversion. By applying these transitions, a CPW-PSPW-CPW structure is designed, fabricated and measured to verify the PSPW’s propagation performance at microwave frequencies. The investigation results show the proposed PSPWs have excellent performance of deep subwavelength spoof SPPs confinement, long propagation length and low bend loss, as well as great design flexibility to engineer the propagation properties by adjusting their geometry dimensions and material parameters. Our work opens up a new avenue for development of various advanced planar integrated plasmonic devices and circuits in microwave and terahertz regimes.

Strongly Confined Spoof Surface Plasmon Polaritons Waveguiding Enabled by Planar Staggered Plasmonic Waveguides.

PubMed

Ye, Longfang; Xiao, Yifan; Liu, Yanhui; Zhang, Liang; Cai, Guoxiong; Liu, Qing Huo

2016-12-05

We demonstrate a novel route to achieving highly efficient and strongly confined spoof surface plasmon polaritons (SPPs) waveguides at subwavelength scale enabled by planar staggered plasmonic waveguides (PSPWs). The structure of these new waveguides consists of an ultrathin metallic strip with periodic subwavelength staggered double groove arrays supported by a flexible dielectric substrate, leading to unique staggered EM coupling and waveguiding phenomenon. The spoof SPP propagation properties, including dispersion relations and near field distributions, are numerically investigated. Furthermore, broadband coplanar waveguide (CPW) to planar staggered plasmonic waveguide (PSPW) transitions are designed to achieve smooth momentum matching and highly efficient spoof SPP mode conversion. By applying these transitions, a CPW-PSPW-CPW structure is designed, fabricated and measured to verify the PSPW's propagation performance at microwave frequencies. The investigation results show the proposed PSPWs have excellent performance of deep subwavelength spoof SPPs confinement, long propagation length and low bend loss, as well as great design flexibility to engineer the propagation properties by adjusting their geometry dimensions and material parameters. Our work opens up a new avenue for development of various advanced planar integrated plasmonic devices and circuits in microwave and terahertz regimes.

Docking alignment system

NASA Technical Reports Server (NTRS)

Monford, Leo G. (Inventor)

1990-01-01

Improved techniques are provided for alignment of two objects. The present invention is particularly suited for three-dimensional translation and three-dimensional rotational alignment of objects in outer space. A camera 18 is fixedly mounted to one object, such as a remote manipulator arm 10 of the spacecraft, while the planar reflective surface 30 is fixed to the other object, such as a grapple fixture 20. A monitor 50 displays in real-time images from the camera, such that the monitor displays both the reflected image of the camera and visible markings on the planar reflective surface when the objects are in proper alignment. The monitor may thus be viewed by the operator and the arm 10 manipulated so that the reflective surface is perpendicular to the optical axis of the camera, the roll of the reflective surface is at a selected angle with respect to the camera, and the camera is spaced a pre-selected distance from the reflective surface.

Improved docking alignment system

NASA Technical Reports Server (NTRS)

Monford, Leo G. (Inventor)

1988-01-01

Improved techniques are provided for the alignment of two objects. The present invention is particularly suited for 3-D translation and 3-D rotational alignment of objects in outer space. A camera is affixed to one object, such as a remote manipulator arm of the spacecraft, while the planar reflective surface is affixed to the other object, such as a grapple fixture. A monitor displays in real-time images from the camera such that the monitor displays both the reflected image of the camera and visible marking on the planar reflective surface when the objects are in proper alignment. The monitor may thus be viewed by the operator and the arm manipulated so that the reflective surface is perpendicular to the optical axis of the camera, the roll of the reflective surface is at a selected angle with respect to the camera, and the camera is spaced a pre-selected distance from the reflective surface.

Summary on Several Key Techniques in 3D Geological Modeling

PubMed Central

2014-01-01

Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized. PMID:24772029

3-D World Modeling For An Autonomous Robot

NASA Astrophysics Data System (ADS)

Goldstein, M.; Pin, F. G.; Weisbin, C. R.

1987-01-01

This paper presents a methodology for a concise representation of the 3-D world model for a mobile robot, using range data. The process starts with the segmentation of the scene into "objects" that are given a unique label, based on principles of range continuity. Then the external surface of each object is partitioned into homogeneous surface patches. Contours of surface patches in 3-D space are identified by estimating the normal and curvature associated with each pixel. The resulting surface patches are then classified as planar, convex or concave. Since the world model uses a volumetric representation for the 3-D environment, planar surfaces are represented by thin volumetric polyhedra. Spherical and cylindrical surfaces are extracted and represented by appropriate volumetric primitives. All other surfaces are represented using the boolean union of spherical volumes (as described in a separate paper by the same authors). The result is a general, concise representation of the external 3-D world, which allows for efficient and robust 3-D object recognition.

Method and apparatus for reducing the drag of flows over surfaces

NASA Technical Reports Server (NTRS)

Keefe, Laurence R. (Inventor)

1998-01-01

An apparatus, and its accompanying method, for reducing the drag of flows over a surface includes arrays of small disks and sensors. The arrays are embedded in the surface and may extend above, or be depressed below, the surface, provided they remain hydraulically smooth either when operating or when inactive. The disks are arranged in arrays of various shapes, and spaced according to the cruising speed of the vehicle on which the arrays are installed. For drag reduction at speeds of the order of 30 meters/second, preferred embodiments include disks that are 0.2 millimeter in diameter and spaced 0.4 millimeter apart. For drag reduction at speeds of the order of 300 meters/second, preferred embodiments include disks that are 0.045 millimeter in diameter and spaced 0.09 millimeter apart. Smaller and larger dimensions for diameter and spacing are also possible. The disks rotate in the plane of the surface, with their rotation axis substantially perpendicular to the surface. The rotating disks produce velocity perturbations parallel to the surface in the overlying boundary layer. The sensors sense the flow at the surface and connect to control circuitry that adjusts the rotation rates and duty cycles of the disks accordingly. Suction and blowing holes can be interspersed among, or made coaxial with, the disks for creating general three-component velocity perturbations in the near-surface region. The surface can be a flat, planar surface or a nonplanar surface, such as a triangular riblet surface. The present apparatus and method have potential applications in the field of aeronautics for improving performance and efficiency of commercial and military aircraft, and in other industries where drag is an obstacle, including gas and oil delivery through long-haul pipelines.

Simulation of Tip-Sample Interaction in the Atomic Force Microscope

NASA Technical Reports Server (NTRS)

Good, Brian S.; Banerjea, Amitava

1994-01-01

Recent simulations of the interaction between planar surfaces and model Atomic Force Microscope (AFM) tips have suggested that there are conditions under which the tip may become unstable and 'avalanche' toward the sample surface. Here we investigate via computer simulation the stability of a variety of model AFM tip configurations with respect to the avalanche transition for a number of fcc metals. We perform Monte-Carlo simulations at room temperature using the Equivalent Crystal Theory (ECT) of Smith and Banerjea. Results are compared with recent experimental results as well as with our earlier work on the avalanche of parallel planar surfaces. Our results on a model single-atom tip are in excellent agreement with recent experiments on tunneling through mechanically-controlled break junctions.

Modeling and simulation of dynamics of a planar-motion rigid body with friction and surface contact

NASA Astrophysics Data System (ADS)

Wang, Xiaojun; Lv, Jing

2017-07-01

The modeling and numerical method for the dynamics of a planar-motion rigid body with frictional contact between plane surfaces were presented based on the theory of contact mechanics and the algorithm of linear complementarity problem (LCP). The Coulomb’s dry friction model is adopted as the friction law, and the normal contact forces are expressed as functions of the local deformations and their speeds in contact bodies. The dynamic equations of the rigid body are obtained by the Lagrange equation. The transition problem of stick-slip motions between contact surfaces is formulated and solved as LCP through establishing the complementary conditions of the friction law. Finally, a numerical example is presented as an example to show the application.

Security hologram foil labels with a design facilitating authenticity testing: effects of mechanical bending of substrates with the glued on holograms

NASA Astrophysics Data System (ADS)

Aubrecht, Ivo

2015-05-01

Optimal design of security holograms or diffractive optically variable image devices (DOVIDs) that would be complex enough to deter counterfeiters from attempts of mimicking but contains features readily recognizable by laymen has been addressed by many experts. This paper tries to discuss effects of mechanical bending of a flexible substrate to visual appearance of a glued-on foil DOVID. Initially plane, the DOVID is deformed to a convex- or concave-shaped curved surface. Theoretical analyses and experimental results assume the surface to be a cylindrical segment and concern rainbow-type surface-relief holograms that are recorded piecewise in a photoresist material, coated on planar and non-planar substrates.

Ultrathin two-dimensional MnO2/graphene hybrid nanostructures for high-performance, flexible planar supercapacitors.

PubMed

Peng, Lele; Peng, Xu; Liu, Borui; Wu, Changzheng; Xie, Yi; Yu, Guihua

2013-05-08

Planar supercapacitors have recently attracted much attention owing to their unique and advantageous design for 2D nanomaterials based energy storage devices. However, improving the electrochemical performance of planar supercapacitors still remains a great challenge. Here we report for the first time a novel, high-performance in-plane supercapacitor based on hybrid nanostructures of quasi-2D ultrathin MnO2/graphene nanosheets. Specifically, the planar structures based on the δ-MnO2 nanosheets integrated on graphene sheets not only introduce more electrochemically active surfaces for absorption/desorption of electrolyte ions, but also bring additional interfaces at the hybridized interlayer areas to facilitate charge transport during charging/discharging processes. The unique structural design for planar supercapacitors enables great performance enhancements compared to graphene-only devices, exhibiting high specific capacitances of 267 F/g at current density of 0.2 A/g and 208 F/g at 10 A/g and excellent rate capability and cycling stability with capacitance retention of 92% after 7000 charge/discharge cycles. Moreover, the high planar malleability of planar supercapacitors makes possible superior flexibility and robust cyclability, yielding capacitance retention over 90% after 1000 times of folding/unfolding. Ultrathin 2D nanomaterials represent a promising material platform to realize highly flexible planar energy storage devices as the power back-ups for stretchable/flexible electronic devices.

DLVO interaction energies between hollow spherical particles and collector surfaces

USDA-ARS?s Scientific Manuscript database

The surface element integration technique was used to systematically study Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies/forces between hollow spherical particles (HPs) and a planar surface or two intercepting half planes under different ionic strength conditions. The inner and outer ...

Automated Coarse Registration of Point Clouds in 3d Urban Scenes Using Voxel Based Plane Constraint

NASA Astrophysics Data System (ADS)

Xu, Y.; Boerner, R.; Yao, W.; Hoegner, L.; Stilla, U.

2017-09-01

For obtaining a full coverage of 3D scans in a large-scale urban area, the registration between point clouds acquired via terrestrial laser scanning (TLS) is normally mandatory. However, due to the complex urban environment, the automatic registration of different scans is still a challenging problem. In this work, we propose an automatic marker free method for fast and coarse registration between point clouds using the geometric constrains of planar patches under a voxel structure. Our proposed method consists of four major steps: the voxelization of the point cloud, the approximation of planar patches, the matching of corresponding patches, and the estimation of transformation parameters. In the voxelization step, the point cloud of each scan is organized with a 3D voxel structure, by which the entire point cloud is partitioned into small individual patches. In the following step, we represent points of each voxel with the approximated plane function, and select those patches resembling planar surfaces. Afterwards, for matching the corresponding patches, a RANSAC-based strategy is applied. Among all the planar patches of a scan, we randomly select a planar patches set of three planar surfaces, in order to build a coordinate frame via their normal vectors and their intersection points. The transformation parameters between scans are calculated from these two coordinate frames. The planar patches set with its transformation parameters owning the largest number of coplanar patches are identified as the optimal candidate set for estimating the correct transformation parameters. The experimental results using TLS datasets of different scenes reveal that our proposed method can be both effective and efficient for the coarse registration task. Especially, for the fast orientation between scans, our proposed method can achieve a registration error of less than around 2 degrees using the testing datasets, and much more efficient than the classical baseline methods.

Stagnation point properties for non-continuum gaseous jet impinging at a flat plate surface from a planar exit

NASA Astrophysics Data System (ADS)

Cai, Chunpei

2013-10-01

In this paper, we investigate highly rarefied gaseous jet flows out of a planar exit and impinging at a normally set flat plate. Especially, we concentrate on the plate center stagnation point pressure and heat flux coefficients. For a specular reflective plate, the stagnation point pressure coefficient can be represented using two non-dimensional factors: the characteristic gas exit speed ratio S0 and the geometry ratio of H/L, where H is the planar exit semi-height and L is the center-to-center distance from the exit to the plate. For a diffuse reflective plate, the stagnation point pressure and heat flux coefficients involve an extra factor of T0/Tw, i.e., the ratio of exit gas temperature to the plate wall temperature. These results allow us to develop four diagrams, from which we can conveniently obtain the pressure and heat flux coefficients for the stagnation impingement point, at the collisionless flow limit. After normalization with these maximum coefficients, the pressure and heat flux coefficient distributions along the surface essentially degenerate to almost identical curves. As a result, with known plate surface pressure coefficient distributions and these diagrams, we can conveniently construct the heat flux coefficient distributions along the plate surface, and vice versa.

Development of a novel precision instrument for high-resolution simultaneous normal and shear force measurements between small planar samples

NASA Astrophysics Data System (ADS)

Lundstrom, Troy; Clark, William; Jalili, Nader

2017-05-01

In the design and development of end effector pads for silicon wafer handling robots, it is imperative that the static friction/adhesion force properties of the pads with respect to a variety of planar surfaces be characterized. In this work, the overall design, calibration, and data acquisition procedure of an instrument developed for performing these measurements on small (<10 mm × 10 mm) planar samples is presented. This device was used to perform adhesion/maximum shear force measurements on polydimethylsiloxane, a silicon wafer, and custom carbon nanotubes forest surfaces. The device was successfully able to measure an effective, mean profile adhesion force of 715 μN between a silicon wafer and a polydimethylsiloxane (2.768 × 10-6 m2) sample. In addition, a nonlinear maximum shear over normal force relationship was also measured between custom carbon nanotubes forest and the silicon wafer surfaces. The maximum shear over a normal force coefficient was found to decrease with increasing initial normal force. Currently, there are numerous devices for measuring normal/shear forces at the nano/micro- and macroscales; however, this device allows for the consistent measurement of these same types of forces on components with surface dimensions ranging from 0.1 mm to 10 mm.

Excitation of the Uller-Zenneck electromagnetic surface waves in the prism-coupled configuration

NASA Astrophysics Data System (ADS)

Rasheed, Mehran; Faryad, Muhammad

2017-08-01

A configuration to excite the Uller-Zenneck surface electromagnetic waves at the planar interfaces of homogeneous and isotropic dielectric materials is proposed and theoretically analyzed. The Uller-Zenneck waves are surface waves that can exist at the planar interface of two dissimilar dielectric materials of which at least one is a lossy dielectric material. In this paper, a slab of a lossy dielectric material was taken with lossless dielectric materials on both sides. A canonical boundary-value problem was set up and solved to find the possible Uller-Zenneck waves and waveguide modes. The Uller-Zenneck waves guided by the slab of the lossy dielectric material were found to be either symmetric or antisymmetric and transmuted into waveguide modes when the thickness of that slab was increased. A prism-coupled configuration was then successfully devised to excite the Uller-Zenneck waves. The results showed that the Uller-Zenneck waves are excited at the same angle of incidence for any thickness of the slab of the lossy dielectric material, whereas the waveguide modes can be excited when the slab is sufficiently thick. The excitation of Uller-Zenneck waves at the planar interfaces with homogeneous and all-dielectric materials can usher in new avenues for the applications for electromagnetic surface waves.

Design and Characterization of Next-Generation Micromirrors Fabricated in a Four-Level, Planarized Surface-Micromachined Polycrystalline Silicon Process

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

Michalicek, M.A.; Comtois, J.H.; Barron, C.C.

This paper describes the design and characterization of several types of micromirror devices to include process capabilities, device modeling, and test data resulting in deflection versus applied potential curves. These micromirror devices are the first to be fabricated in the state-of-the-art four-level planarized polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics which have previously been unrealizable in standard three-layer polysilicon processes. This paper describes such characteristics as elevated address electrodes, individual address wiring beneath the device, planarized mirror surfaces usingmore » Chemical Mechanical Polishing (CMP), unique post-process metallization, and the best active surface area to date. This paper presents the design, fabrication, modeling, and characterization of several variations of Flexure-Beam (FBMD) and Axial-Rotation Micromirror Devices (ARMD). The released devices are first metallized using a standard sputtering technique relying on metallization guards and masks that are fabricated next to the devices. Such guards are shown to enable the sharing of bond pads between numerous arrays of micromirrors in order to maximize the number of on-chip test arrays. The devices are modeled and then empirically characterized using a laser interferometer setup located at the Air Force Institute of Technology (AFIT) at Wright-Patterson AFB in Dayton, Ohio. Unique design considerations for these devices and the process are also discussed.« less

Wetting Transition of Nonpolar Neutral Molecule System on a Neutral and Atomic Length Scale Roughness Substrate

NASA Astrophysics Data System (ADS)

Zhou, Shiqi

2018-03-01

One recently proposed new method for accurately determining wetting temperature is applied to the wetting transition occurring in a single component nonpolar neutral molecule system near a neutral planar substrate with roughness produced by cosinusoidal modulation(s). New observations are summarized into five points: (i) for a planar substrate superimposed with one cosinusoidal modulation, with increasing of the periodicity length or the surface attraction force field, or decreasing of the amplitude, wetting temperature T_W drops accordingly and the three parameters show multiplication effect; moreover, both the periodicity length and amplitude effect curves display pole phenomena and saturation phenomena, and the T_W saturation occurs at small (for case of large amplitude) or large (for case of small amplitude) periodicity length side, respectively. (ii) In the case of the planar substrate superimposed with two cosinusoidal modulations with equal periodicity length, the initial phase difference is critical issue that influences the T_W, which decreases with the initial phase difference. (iii) In the case of the planar substrate superimposed with two cosinusoidal modulations with zero phase difference, change of the T_W with one periodicity length under the condition of another periodicity length unchanged is non-monotonous. (iv) When the parameters are chosen such that the T_W draws ever closer to the bulk critical temperature, wetting transition on the roughness substrate eventually does not occur. (v) The present microscopic calculation challenges traditional macroscopic theory by confirming that the atomic length scale roughness always renders the surface less hydrophilic and whereas the mesoscopical roughness renders the surface more hydrophilic. All of these observations summarized can be reasonably explained by the relative strength of the attraction actually enjoyed by the surface gas molecules to the attraction the gas molecules can get when in bulk.

Catadioptric planar compound eye with large field of view.

PubMed

Deng, Huaxia; Gao, Xicheng; Ma, Mengchao; Li, Yunyang; Li, Hang; Zhang, Jin; Zhong, Xiang

2018-05-14

The planar compound eye has the advantages of simple structure and no requirement for complex relay optical elements, but the field of view (FOV) is very difficult to expand. Overcoming the limitation of FOV, especially with simple structures, is a great challenge for the development of planar compound eyes. Different from the existing designs that only considering refraction, this article proposes a catadioptric planar compound eye based on the reflection and refraction to expand the FOV. In the proposed design, the incident light from a large angle is reflected into the lenslet array by two rotationally symmetric mirrors whose surface equations are optimized by mathematical and optical softwares. The FOV of the proposed catadioptric planar compound eye theoretically can reach 96.6°, which is much wider than the opening record of 70°. Moreover, no distortion of the imaging system can be obtained theoretically in this design. Simulation results show a linearity of better than 99% for the most of the incident angles. The verification experiments show that the FOV of the proposed device can reach 90.7° while the FOV of the corresponding planar compound eye without mirrors is 41.6°. The proposed catadioptric planar compound eye has the great potential in monitoring, detection and virtual reality since the FOV has been widen significantly.

Nano-textured fluidic biochip as biological filter for selective survival of neuronal cells.

PubMed

Han, Hsieh-Cheng; Lo, Hung-Chun; Wu, Chia-Yu; Chen, Kuei-Hsien; Chen, Li-Chyong; Ou, Keng-Liang; Hosseinkhani, Hossein

2015-06-01

This is an innovative study to engineer biological filter to evaluate the effect of template surface structure and physiochemical properties that can be used for wide variety of applications in biological, health care as well as environmental protection. Specifically, planar silicon (Si) wafer and arrayed Si nano-tips (SiNT) templates were fabricated and coated with gold for various lengths of time to study the effect of surface charge, surface roughness, and hydrophilicity on biological activity of rat pheochromocytoma cell lines PC12. The initial growth and proliferation of PC12 cells on Si and SiNT templates showed an antipathy for the ultra-sharp SiNTs templates. In contrast, the same cells demonstrated a preferable adherence to and proliferation on planar Si templates, resulting in higher cell densities by three orders of magnitude than those on SiNT templates. It is hypothesized that SiNTs array does generate nano-fluidic effect such that the effective contact region for aqueous solution on SiNTs is lower than that on planar Si templates, thus decreasing adsorbable area for cell viability and survival. Moreover, the effect of the gold coating on cell number density was analyzed in terms of the surface roughness, zeta potential and wetting properties of the templates. It was determined that surface charge, as measured by the zeta potential, strongly correlated with the trend observed in the surface cell density, whereas no such correlation was observed for surface roughness or wetting properties in the ranges of our experiment conditions. © 2014 Wiley Periodicals, Inc.

Generalized surface tension bounds in vacuum decay

NASA Astrophysics Data System (ADS)

Masoumi, Ali; Paban, Sonia; Weinberg, Erick J.

2018-02-01

Coleman and De Luccia (CDL) showed that gravitational effects can prevent the decay by bubble nucleation of a Minkowski or AdS false vacuum. In their thin-wall approximation this happens whenever the surface tension in the bubble wall exceeds an upper bound proportional to the difference of the square roots of the true and false vacuum energy densities. Recently it was shown that there is another type of thin-wall regime that differs from that of CDL in that the radius of curvature grows substantially as one moves through the wall. Not only does the CDL derivation of the bound fail in this case, but also its very formulation becomes ambiguous because the surface tension is not well defined. We propose a definition of the surface tension and show that it obeys a bound similar in form to that of the CDL case. We then show that both thin-wall bounds are special cases of a more general bound that is satisfied for all bounce solutions with Minkowski or AdS false vacua. We discuss the limit where the parameters of the theory attain critical values and the bound is saturated. The bounce solution then disappears and a static planar domain wall solution appears in its stead. The scalar field potential then is of the form expected in supergravity, but this is only guaranteed along the trajectory in field space traced out by the bounce.

Surface-directed capillary system; theory, experiments and applications.

PubMed

Bouaidat, Salim; Hansen, Ole; Bruus, Henrik; Berendsen, Christian; Bau-Madsen, Niels Kristian; Thomsen, Peter; Wolff, Anders; Jonsmann, Jacques

2005-08-01

We present a capillary flow system for liquid transport in microsystems. Our simple microfluidic system consists of two planar parallel surfaces, separated by spacers. One of the surfaces is entirely hydrophobic, the other mainly hydrophobic, but with hydrophilic pathways defined on it by photolithographic means. By controlling the wetting properties of the surfaces in this manner, the liquid can be confined to certain areas defined by the hydrophilic pathways. This technique eliminates the need for alignment of the two surfaces. Patterned plasma-polymerized hexafluoropropene constitutes the hydrophobic areas, whereas the untreated glass surface constitutes the hydrophilic pathways. We developed a theoretical model of the capillary flow and obtained analytical solutions which are in good agreement with the experimental results. The capillarity-driven microflow system was also used to pattern and immobilize biological material on planar substrates: well-defined 200 microm wide strips of human cells (HeLa) and fluorescence labelled proteins (fluorescein isothiocyanate-labelled bovine serum albumin, i.e., FITC-BSA) were fabricated using the capillary flow system presented here.

On-Surface Synthesis and Characterization of Honeycombene Oligophenylene Macrocycles.

PubMed

Chen, Min; Shang, Jian; Wang, Yongfeng; Wu, Kai; Kuttner, Julian; Hilt, Gerhard; Hieringer, Wolfgang; Gottfried, J Michael

2017-01-24

We report the on-surface formation and characterization of [30]-honeycombene, a cyclotriacontaphenylene, which consists of 30 phenyl rings (C 180 H 120 ) and has a diameter of 4.0 nm. This shape-persistent, conjugated, and unsubstituted hexagonal hydrocarbon macrocycle was obtained by solvent-free synthesis on a silver (111) single-crystal surface, making solubility-enhancing alkyl side groups unnecessary. Side products include strained macrocycles with square, pentagonal, and heptagonal shape. The molecules were characterized by scanning tunneling microscopy and density functional theory (DFT) calculations. On the Ag(111) surface, the macrocycles act as molecular quantum corrals and lead to the confinement of surface-state electrons inside the central cavity. The energy of the confined surface state correlates with the size of the macrocycle and is well described by a particle-in-the-box model. Tunneling spectroscopy suggests conjugation within the planar rings and reveals influences of self-assembly on the electronic structure. While the adsorbed molecules appear to be approximately planar, the free molecules have nonplanar conformation, according to DFT.

A flexible nanobrush pad for the chemical mechanical planarization of Cu/ultra-low-к materials

NASA Astrophysics Data System (ADS)

Han, Guiquan; Liu, Yuhong; Lu, Xinchun; Luo, Jianbin

2012-10-01

A new idea of polishing pad called flexible nanobrush pad (FNP) has been proposed for the low down pressure chemical mechanical planarization (CMP) process of Cu/ultra-low-к materials. The FNP was designed with a surface layer of flexible brush-like nanofibers which can `actively' carry nanoscale abrasives in slurry independent of the down pressure. Better planarization performances including high material removal rate, good planarization, good polishing uniformity, and low defectivity are expected in the CMP process under the low down pressure with such kind of pad. The FNP can be made by template-assisted replication or template-based synthesis methods, which will be driven by the development of the preparation technologies for ordered nanostructure arrays. The present work would potentially provide a new solution for the Cu/ultra-low-к CMP process.

Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces

PubMed Central

Li, Yong; Liang, Bin; Gu, Zhong-ming; Zou, Xin-ye; Cheng, Jian-chun

2013-01-01

The introduction of metasurfaces has renewed the Snell's law and opened up new degrees of freedom to tailor the optical wavefront at will. Here, we theoretically demonstrate that the generalized Snell's law can be achieved for reflected acoustic waves based on ultrathin planar acoustic metasurfaces. The metasurfaces are constructed with eight units of a solid structure to provide discrete phase shifts covering the full 2π span with steps of π/4 by coiling up the space. By careful selection of the phase profiles in the transverse direction of the metasurfaces, some fascinating wavefront engineering phenomena are demonstrated, such as anomalous reflections, conversion of propagating waves into surface waves, planar aberration-free lens and nondiffracting Bessel beam generated by planar acoustic axicon. Our results could open up a new avenue for acoustic wavefront engineering and manipulations. PMID:23986034

Planar spoof plasmonic ultra-wideband filter based on low-loss and compact terahertz waveguide corrugated with dumbbell grooves.

PubMed

Zhou, Yong Jin; Yang, Bao Jia

2015-05-10

Although subwavelength planar terahertz (THz) plasmonic devices can be implemented based on planar spoof surface plasmons (SPs), they still suffer from a little high propagation loss. Here the dispersion and propagation characteristics of the spoof plasmonic waveguide composed of double metal strips corrugated with dumbbell shaped grooves have been investigated. It has been found that much lower propagation loss and longer propagation length can be achieved based on the waveguide compared with the conventional spoof plasmonic waveguide with rectangular grooves. Moreover, the waveguide can implement a decrease in size of about 22%. An ultra-wideband THz plasmonic filter for planar circuits has been demonstrated based on the proposed waveguide. The experimental verification at the microwave frequency has been conducted by scaling up the geometry size of the filter.

Efficient Planar Perovskite Solar Cells Using Passivated Tin Oxide as an Electron Transport Layer.

PubMed

Lee, Yonghui; Lee, Seunghwan; Seo, Gabseok; Paek, Sanghyun; Cho, Kyung Taek; Huckaba, Aron J; Calizzi, Marco; Choi, Dong-Won; Park, Jin-Seong; Lee, Dongwook; Lee, Hyo Joong; Asiri, Abdullah M; Nazeeruddin, Mohammad Khaja

2018-06-01

Planar perovskite solar cells using low-temperature atomic layer deposition (ALD) of the SnO 2 electron transporting layer (ETL), with excellent electron extraction and hole-blocking ability, offer significant advantages compared with high-temperature deposition methods. The optical, chemical, and electrical properties of the ALD SnO 2 layer and its influence on the device performance are investigated. It is found that surface passivation of SnO 2 is essential to reduce charge recombination at the perovskite and ETL interface and show that the fabricated planar perovskite solar cells exhibit high reproducibility, stability, and power conversion efficiency of 20%.

Numerical integration techniques for curved-element discretizations of molecule-solvent interfaces.

PubMed

Bardhan, Jaydeep P; Altman, Michael D; Willis, David J; Lippow, Shaun M; Tidor, Bruce; White, Jacob K

2007-07-07

Surface formulations of biophysical modeling problems offer attractive theoretical and computational properties. Numerical simulations based on these formulations usually begin with discretization of the surface under consideration; often, the surface is curved, possessing complicated structure and possibly singularities. Numerical simulations commonly are based on approximate, rather than exact, discretizations of these surfaces. To assess the strength of the dependence of simulation accuracy on the fidelity of surface representation, here methods were developed to model several important surface formulations using exact surface discretizations. Following and refining Zauhar's work [J. Comput.-Aided Mol. Des. 9, 149 (1995)], two classes of curved elements were defined that can exactly discretize the van der Waals, solvent-accessible, and solvent-excluded (molecular) surfaces. Numerical integration techniques are presented that can accurately evaluate nonsingular and singular integrals over these curved surfaces. After validating the exactness of the surface discretizations and demonstrating the correctness of the presented integration methods, a set of calculations are presented that compare the accuracy of approximate, planar-triangle-based discretizations and exact, curved-element-based simulations of surface-generalized-Born (sGB), surface-continuum van der Waals (scvdW), and boundary-element method (BEM) electrostatics problems. Results demonstrate that continuum electrostatic calculations with BEM using curved elements, piecewise-constant basis functions, and centroid collocation are nearly ten times more accurate than planar-triangle BEM for basis sets of comparable size. The sGB and scvdW calculations give exceptional accuracy even for the coarsest obtainable discretized surfaces. The extra accuracy is attributed to the exact representation of the solute-solvent interface; in contrast, commonly used planar-triangle discretizations can only offer improved approximations with increasing discretization and associated increases in computational resources. The results clearly demonstrate that the methods for approximate integration on an exact geometry are far more accurate than exact integration on an approximate geometry. A MATLAB implementation of the presented integration methods and sample data files containing curved-element discretizations of several small molecules are available online as supplemental material.

Optical analysis of a III-V-nanowire-array-on-Si dual junction solar cell.

PubMed

Chen, Yang; Höhn, Oliver; Tucher, Nico; Pistol, Mats-Erik; Anttu, Nicklas

2017-08-07

A tandem solar cell consisting of a III-V nanowire subcell on top of a planar Si subcell is a promising candidate for next generation photovoltaics due to the potential for high efficiency. However, for success with such applications, the geometry of the system must be optimized for absorption of sunlight. Here, we consider this absorption through optics modeling. Similarly, as for a bulk dual-junction tandem system on a silicon bottom cell, a bandgap of approximately 1.7 eV is optimum for the nanowire top cell. First, we consider a simplified system of bare, uncoated III-V nanowires on the silicon substrate and optimize the absorption in the nanowires. We find that an optimum absorption in 2000 nm long nanowires is reached for a dense array of approximately 15 nanowires per square micrometer. However, when we coat such an array with a conformal indium tin oxide (ITO) top contact layer, a substantial absorption loss occurs in the ITO. This ITO could absorb 37% of the low energy photons intended for the silicon subcell. By moving to a design with a 50 nm thick, planarized ITO top layer, we can reduce this ITO absorption to 5%. However, such a planarized design introduces additional reflection losses. We show that these reflection losses can be reduced with a 100 nm thick SiO 2 anti-reflection coating on top of the ITO layer. When we at the same time include a Si 3 N 4 layer with a thickness of 90 nm on the silicon surface between the nanowires, we can reduce the average reflection loss of the silicon cell from 17% to 4%. Finally, we show that different approximate models for the absorption in the silicon substrate can lead to a 15% variation in the estimated photocurrent density in the silicon subcell.

Electron heated target temperature measurements in petawatt laser experiments based on extreme ultraviolet imaging and spectroscopy.

PubMed

Ma, T; Beg, F N; MacPhee, A G; Chung, H-K; Key, M H; Mackinnon, A J; Patel, P K; Hatchett, S; Akli, K U; Stephens, R B; Chen, C D; Freeman, R R; Link, A; Offermann, D T; Ovchinnikov, V; Van Woerkom, L D

2008-10-01

Three independent methods (extreme ultraviolet spectroscopy, imaging at 68 and 256 eV) have been used to measure planar target rear surface plasma temperature due to heating by hot electrons. The hot electrons are produced by ultraintense laser-plasma interactions using the 150 J, 0.5 ps Titan laser. Soft x-ray spectroscopy in the 50-400 eV region and imaging at the 68 and 256 eV photon energies give a planar deuterated carbon target rear surface pre-expansion temperature in the 125-150 eV range, with the rear plasma plume averaging a temperature approximately 74 eV.

Novel electrostatic attraction from plasmon fluctuations

PubMed

Lau; Levine; Pincus

2000-05-01

In this Letter, we show that, at low temperatures, zero-point fluctuations of the plasmon modes of two mutually coupled 2D planar Wigner crystals give rise to a novel long-range attractive force. For the case where the distance d between two planar surfaces is large, this attractive force has an unusual power-law decay, which scales as d(-7/2), unlike other fluctuation-induced forces. Specifically, we note that its range is longer than the "standard" zero-temperature van der Waals interaction. This result may, in principle, be observed in bilayer electronic systems and provides insight into the nature of correlation effects for highly charged surfaces.

Control characteristics for wrap-around fins on cruise missiles configurations

NASA Technical Reports Server (NTRS)

Sawyer, W. C.; Monta, W. J.; Carter, W. V.; Alexander, W. K.

1981-01-01

This paper presents selected results of a panel loads study conducted as part of the final phase of an extensive investigation of an air-breathing missile concept employing wrap-around aerodynamic surfaces. Typical results for M = 2.36 are presented for the fin load results, plus a brief review of basic results of the previously reported tests. Vapor screen results are also discussed. The present results indicate that the fin load characteristics are nearly identical for planar and curved fins having the same projected planform and would permit the use of planar-surface predictions for supersonic speeds in the preliminary design stages of missiles employing wrap-around curved fins.

Improved Design of Optical MEMS Using the SUMMiT Fabrication Process

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

Michalicek, M.A.; Comtois, J.H.; Barron, C.C.

This paper describes the design and fabrication of optical Microelectromechanical Systems (MEMS) devices using the Sandia Ultra planar Multilevel MEMS Technology (SUMMiT) fabrication process. This state of the art process, offered by Sandia National Laboratories, provides unique and very advantageous features which make it ideal for optical devices. This enabling process permits the development of micromirror devices with near ideal characteristics which have previously been unrealizable in standard polysilicon processes. This paper describes such characteristics as elevated address electrodes, individual address wiring beneath the device, planarized mirror surfaces, unique post-process metallization, and the best active surface area to date.

Simulation study on improving efficiencies of perovskite solar cell: Introducing nano textures on it

NASA Astrophysics Data System (ADS)

Xie, Ziang; Sun, Shuren; Wang, Wei; Qin, Laixiang; Yan, Yu; Hou, Ruixiang; Qin, G. G.

2018-03-01

We report that the power conversion efficiencies (PCEs) of the planar CH3NH3PbI3 solar cells (SCs) can be largely improved by fabricating nano textures on the SC surface. With the finite difference time domain (FDTD) method, the ultimate efficiencies of the planar CH3NH3PbI3 SCs with two types of nano textures are investigated: the column-shaped nano hollow (CLNH) array and the cone-shaped nano hollow (CNNH) array. For the nano textured CH3NH3PbI3 SCs with photovoltaic layer depth in the range of 125 nm ∼ 500 nm, when the array period and filling fraction of the nano textures are optimized, in comparison with the planar ones, their PCE increased 42% ∼ 84% for the CLNH textured ones, and 52% ∼ 63% for the CNNH textured ones. As a conclusion, introduction of nano textures on the SC surface is a promising route for improving the PCEs of the perovskite SCs.

3-D Modeling of Planar Target-Mount Perturbation Experiments on OMEGA

NASA Astrophysics Data System (ADS)

Collins, T. J. B.; Marshall, F. J.; Marozas, J. A.; Bonino, M. J.; Forties, R.; Goncharov, V. N.; Igumenshchev, I. V.; McKenty, P. W.; Smalyuk, V. A.

2008-11-01

OMEGA cryogenic targets are suspended in the target chamber using four spider silks attached to a C-shaped mount. The spider silks are typically composed of two entwined protein strands comparable to 1 μm in diameter. The silks and mount refract the incident laser light and cast shadows on the target surface. Experiments to measure the effects of the silks on target illumination have been performed in planar geometry using silks suspended parallel to a 20-μm-thick laser-driven target. The evolution of the surface perturbations introduced by the silks was measured using x-ray backlighting. The results of these experiments will be compared to simulations performed with DRACO, employing three-dimensional (3-D) planar hydrodynamics and a new 3-D refractive ray-trace package written specifically for this geometry. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

Insight into Evolution, Processing and Performance of Multi-length-scale Structures in Planar Heterojunction Perovskite Solar Cells.

PubMed

Huang, Yu-Ching; Tsao, Cheng-Si; Cho, Yi-Ju; Chen, Kuan-Chen; Chiang, Kai-Ming; Hsiao, Sheng-Yi; Chen, Chang-Wen; Su, Chun-Jen; Jeng, U-Ser; Lin, Hao-Wu

2015-09-04

The structural characterization correlated to the processing control of hierarchical structure of planar heterojunction perovskite layer is still incomplete due to the limitations of conventional microscopy and X-ray diffraction. This present study performed the simultaneously grazing-incidence small-angle scattering and wide-angle scattering (GISAXS/GIWAXS) techniques to quantitatively probe the hierarchical structure of the planar heterojunction perovskite solar cells. The result is complementary to the currently microscopic study. Correlation between the crystallization behavior, crystal orientation, nano- and meso-scale internal structure and surface morphology of perovskite film as functions of various processing control parameters is reported for the first time. The structural transition from the fractal pore network to the surface fractal can be tuned by the chloride percentage. The GISAXS/GIWAXS measurement provides the comprehensive understanding of concurrent evolution of the film morphology and crystallization correlated to the high performance. The result can provide the insight into formation mechanism and rational synthesis design.

Insight into Evolution, Processing and Performance of Multi-length-scale Structures in Planar Heterojunction Perovskite Solar Cells

NASA Astrophysics Data System (ADS)

Huang, Yu-Ching; Tsao, Cheng-Si; Cho, Yi-Ju; Chen, Kuan-Chen; Chiang, Kai-Ming; Hsiao, Sheng-Yi; Chen, Chang-Wen; Su, Chun-Jen; Jeng, U.-Ser; Lin, Hao-Wu

2015-09-01

The structural characterization correlated to the processing control of hierarchical structure of planar heterojunction perovskite layer is still incomplete due to the limitations of conventional microscopy and X-ray diffraction. This present study performed the simultaneously grazing-incidence small-angle scattering and wide-angle scattering (GISAXS/GIWAXS) techniques to quantitatively probe the hierarchical structure of the planar heterojunction perovskite solar cells. The result is complementary to the currently microscopic study. Correlation between the crystallization behavior, crystal orientation, nano- and meso-scale internal structure and surface morphology of perovskite film as functions of various processing control parameters is reported for the first time. The structural transition from the fractal pore network to the surface fractal can be tuned by the chloride percentage. The GISAXS/GIWAXS measurement provides the comprehensive understanding of concurrent evolution of the film morphology and crystallization correlated to the high performance. The result can provide the insight into formation mechanism and rational synthesis design.

Surface Plasmon Polariton-Assisted Long-Range Exciton Transport in Monolayer Semiconductor Lateral Heterostructure

NASA Astrophysics Data System (ADS)

Shi, Jinwei; Lin, Meng-Hsien; Chen, Yi-Tong; Estakhri, Nasim Mohammadi; Tseng, Guo-Wei; Wang, Yanrong; Chen, Hung-Ying; Chen, Chun-An; Shih, Chih-Kang; Alã¹, Andrea; Li, Xiaoqin; Lee, Yi-Hsien; Gwo, Shangjr

Recently, two-dimensional (2D) semiconductor heterostructures, i.e., atomically thin lateral heterostructures (LHSs) based on transition metal dichalcogenides (TMDs) have been demonstrated. In an optically excited LHS, exciton transport is typically limited to a rather short spatial range ( 1 micron). Furthermore, additional losses may occur at the lateral interfacial regions. Here, to overcome these challenges, we experimentally implement a planar metal-oxide-semiconductor (MOS) structure by placing a monolayer of WS2/MoS2 LHS on top of an Al2O3 capped Ag single-crystalline plate. We found that the exciton transport range can be extended to tens of microns. The process of long-range exciton transport in the MOS structure is confirmed to be mediated by an exciton-surface plasmon polariton-exciton conversion mechanism, which allows a cascaded energy transfer process. Thus, the planar MOS structure provides a platform seamlessly combining 2D light-emitting materials with plasmonic planar waveguides, offering great potential for developing integrated photonic/plasmonic functionalities.

N -Sm A -Sm C phase transitions probed by a pair of elastically bound colloids

NASA Astrophysics Data System (ADS)

M, Muhammed Rasi; Zuhail, K. P.; Roy, Arun; Dhara, Surajit

2018-03-01

The competing effect of surface anchoring of dispersed microparticles and elasticity of nematic and cholesteric liquid crystals has been shown to stabilize a variety of topological defects. Here we study a pair of colloidal microparticles with homeotropic and planar surface anchoring across N -Sm A -Sm C phase transitions. We show that below the Sm A -Sm C phase transition the temperature dependence of interparticle separation (D ) of colloids with homeotropic anchoring shows a power-law behavior; D ˜(1-T /TA C) α , with an exponent α ≈0.5 . For colloids with planar surface anchoring the angle between the joining line of the centers of the two colloids and the far field director shows characteristic variation elucidating the phase transitions.

Electromagnetic acoustic transducer

DOEpatents

Alers, George A.; Burns, Jr., Leigh R.; MacLauchlan, Daniel T.

1988-01-01

A noncontact ultrasonic transducer for studying the acoustic properties of a metal workpiece includes a generally planar magnetizing coil positioned above the surface of the workpiece, and a generally planar eddy current coil between the magnetizing coil and the workpiece. When a large current is passed through the magnetizing coil, a large magnetic field is applied to the near-surface regions of the workpiece. The eddy current coil can then be operated as a transmitter by passing an alternating current therethrough to excite ultrasonic waves in the surface of the workpiece, or operated as a passive receiver to sense ultrasonic waves in the surface by measuring the output signal. The geometries of the two coils can be varied widely to be effective for different types of ultrasonic waves. The coils are preferably packaged in a housing which does not interfere with their operation, but protects them from a variety of adverse environmental conditions.

A three-dimensional microelectrode array composed of vertically aligned ultra-dense carbon nanotube networks

NASA Astrophysics Data System (ADS)

Nick, C.; Yadav, S.; Joshi, R.; Schneider, J. J.; Thielemann, C.

2015-07-01

Electrodes based on carbon nanotubes are a promising approach to manufacture highly sensitive sensors with a low limit of signal detection and a high signal-to-noise ratio. This is achieved by dramatically increasing the electrochemical active surface area without increasing the overall geometrical dimensions. Typically, carbon nanotube electrodes are nearly planar and composed of randomly distributed carbon nanotube networks having a limited surface gain for a specific geometrical surface area. To overcome this limitation, we have introduced vertically aligned carbon nanotube (VACNT) networks as electrodes, which are arranged in a microelectrode pattern of 60 single electrodes. Each microelectrode features a very high aspect ratio of more than 300 and thus a dramatically increased surface area. These microelectrodes composed of VACNT networks display dramatically decreased impedance over the entire frequency range compared to planar microelectrodes caused by the enormous capacity increase. This is experimentally verified by electrochemical impedance spectroscopy and cyclic voltammetry.

Growth and quantum transport properties of vertical Bi2Se3 nanoplate films on Si substrates.

PubMed

Li, Mingze; Wang, Zhenhua; Yang, Liang; Pan, Desheng; Li, Da; Gao, Xuan P A; Zhang, Zhidong

2018-08-03

Controlling the growth direction (planar versus vertical) and surface-to-bulk ratio can lead to lots of unique properties for two-dimensional layered materials. We report a simple method to fabricate continuous films of vertical Bi 2 Se 3 nanoplates on Si substrate and investigate the quantum transport properties of such films. In contrast to (001) oriented planar Bi 2 Se 3 nanoplate film, vertical Bi 2 Se 3 nanoplate films are enclosed by (015) facets, which possess high surface-to-bulk ratio that can enhance the quantum transport property of topological surface states. And by controlling the compactness of vertical Bi 2 Se 3 nanoplates, we realized an effective tuning of the weak antilocalization effect from topological surface states in Bi 2 Se 3 films. Our work paves a way for exploring the unique transport properties of this unconventional structure topological insulator film.

Aqueous gating of van der Waals materials on bilayer nanopaper.

PubMed

Bao, Wenzhong; Fang, Zhiqiang; Wan, Jiayu; Dai, Jiaqi; Zhu, Hongli; Han, Xiaogang; Yang, Xiaofeng; Preston, Colin; Hu, Liangbing

2014-10-28

In this work, we report transistors made of van der Waals materials on a mesoporous paper with a smooth nanoscale surface. The aqueous transistor has a novel planar structure with source, drain, and gate electrodes on the same surface of the paper, while the mesoporous paper is used as an electrolyte reservoir. These transistors are enabled by an all-cellulose paper with nanofibrillated cellulose (NFC) on the top surface that leads to an excellent surface smoothness, while the rest of the microsized cellulose fibers can absorb electrolyte effectively. Based on two-dimensional van der Waals materials, including MoS2 and graphene, we demonstrate high-performance transistors with a large on-off ratio and low subthreshold swing. Such planar transistors with absorbed electrolyte gating can be used as sensors integrated with other components to form paper microfluidic systems. This study is significant for future paper-based electronics and biosensors.

Field-Induced and Thermal Electron Currents from Earthed Spherical Emitters

NASA Astrophysics Data System (ADS)

Holgate, J. T.; Coppins, M.

2017-04-01

The theories of electron emission from planar surfaces are well understood, but they are not suitable for describing emission from spherical surfaces; their incorrect application to highly curved, nanometer-scale surfaces can overestimate the emitted current by several orders of magnitude. This inaccuracy is of particular concern for describing modern nanoscale electron sources, which continue to be modeled using the planar equations. In this paper, the field-induced and thermal currents are treated in a unified way to produce Fowler-Nordheim-type and Richardson-Schottky-type equations for the emitted current density from earthed nanoscale spherical surfaces. The limits of applicability of these derived expressions are considered along with the energy spectra of the emitted electrons. Within the relevant limits of validity, these equations are shown to reproduce the results of precise numerical calculations of the emitted current densities. The methods used here are adaptable to other one-dimensional emission problems.

Slant Perception Under Stereomicroscopy.

PubMed

Horvath, Samantha; Macdonald, Kori; Galeotti, John; Klatzky, Roberta L

2017-11-01

Objective These studies used threshold and slant-matching tasks to assess and quantitatively measure human perception of 3-D planar images viewed through a stereomicroscope. The results are intended for use in developing augmented-reality surgical aids. Background Substantial research demonstrates that slant perception is performed with high accuracy from monocular and binocular cues, but less research concerns the effects of magnification. Viewing through a microscope affects the utility of monocular and stereo slant cues, but its impact is as yet unknown. Method Participants performed in a threshold slant-detection task and matched the slant of a tool to a surface. Different stimuli and monocular versus binocular viewing conditions were implemented to isolate stereo cues alone, stereo with perspective cues, accommodation cue only, and cues intrinsic to optical-coherence-tomography images. Results At magnification of 5x, slant thresholds with stimuli providing stereo cues approximated those reported for direct viewing, about 12°. Most participants (75%) who passed a stereoacuity pretest could match a tool to the slant of a surface viewed with stereo at 5x magnification, with mean compressive error of about 20% for optimized surfaces. Slant matching to optical coherence tomography images of the cornea viewed under the microscope was also demonstrated. Conclusion Despite the distortions and cue loss introduced by viewing under the stereomicroscope, most participants were able to detect and interact with slanted surfaces. Application The experiments demonstrated sensitivity to surface slant that supports the development of augmented-reality systems to aid microscope-aided surgery.

Planar-Processed Polymer Transistors.

PubMed

Xu, Yong; Sun, Huabin; Shin, Eul-Yong; Lin, Yen-Fu; Li, Wenwu; Noh, Yong-Young

2016-10-01

Planar-processed polymer transistors are proposed where the effective charge injection and the split unipolar charge transport are all on the top surface of the polymer film, showing ideal device characteristics with unparalleled performance. This technique provides a great solution to the problem of fabrication limitations, the ambiguous operating principle, and the performance improvements in practical applications of conjugated-polymer transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultraviolet-ozone surface modification for non-wetting hole transport materials based inverted planar perovskite solar cells with efficiency exceeding 18%

NASA Astrophysics Data System (ADS)

Xu, Xiuwen; Ma, Chunqing; Cheng, Yuanhang; Xie, Yue-Min; Yi, Xueping; Gautam, Bhoj; Chen, Shengmei; Li, Ho-Wa; Lee, Chun-Sing; So, Franky; Tsang, Sai-Wing

2017-08-01

Non-wetting hole transport materials (HTMs) have great potential in facilitating large-sized perovskite crystal growth and enhancing device stability by opposing moisture ingress, However, the severe non-wetting issue limits the wide application of these materials in low-temperature solution-processed inverted planar perovskite solar cells (PVSCs), and corresponding devices are rarely reported. Here, a facile ultraviolet-ozone (UVO) modification method is demonstrated to overcome this issue. By carefully controlling the UVO modification time, the surface wettability of poly-TPD can be tuned without affecting the bulk properties of the film, hence perovskite films with desired grain size and excellent coverage can be deposited via a one-step spin-coating method. Benefiting from the high-quality perovskite, well-matched energy level alignment and hydrophobic property of poly-TPD, the resulting PVSCs show a champion power conversion efficiency of 18.19% with significantly enhanced stability as compared to the PEDOT:PSS counterparts. Moreover, the UVO modification approach also demonstrates its validity when being extended to other hydrophobic HTMs. This work not only provides a general strategy to broaden the selection pool of HTMs for solution-processed inverted planar PVSCs, but also may triggers the exploration of more advanced strategies to make non-wetting HTMs applicable in solution-processed inverted planar PVSCs.

Shock-induced perturbation evolution in planar laser targets

NASA Astrophysics Data System (ADS)

Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J. L.; Kessler, T. J.; Schmitt, A. J.; Obenschain, S. P.; Metzler, N.; Oh, J.

2013-10-01

Experimental studies of hydrodynamic perturbation evolution triggered by a laser-driven shock wave in a planar target done on the KrF Nike laser facility are reported. The targets were made of solid plastic and/or plastic foam with single mode sinusoidal perturbation on the front or back surface or plastic/foam interface. Two specific cases are discussed. When a planar solid plastic target rippled at the front side is irradiated with a 350 ps long laser pulse, ablative Richtmyer-Meshkov (RM) oscillation of its areal mass modulation amplitude is detected while the laser is on, followed by observed strong oscillations of the areal mass in the unsupported shock flow after the laser pulse ends. When the target is rippled at the rear side, the nature of the perturbation evolution after the shock breakout is determined by the strength of the laser-driven shock wave. At pressure below 1 Mbar shock interaction with rear-surface ripples produces planar collimated jets manifesting the development of a classical RM instability in a weakly compressible shocked fluid. At shock pressure ~ 8 Mbar sufficient for vaporizing the shocked target material we observed instead the strong areal mass oscillations characteristic of a rippled centered rarefaction wave. Work supported by US DOE, Defense Programs.

Ultrafast carrier dynamics in GaN/InGaN multiple quantum wells nanorods

NASA Astrophysics Data System (ADS)

Chen, Weijian; Wen, Xiaoming; Latzel, Michael; Yang, Jianfeng; Huang, Shujuan; Shrestha, Santosh; Patterson, Robert; Christiansen, Silke; Conibeer, Gavin

2018-01-01

GaN/InGaN multiple quantum wells (MQW) is a promising material for high-efficiency solid-state lighting. Ultrafast optical pump-probe spectroscopy is an important characterization technique for examining fundamental phenomena in semiconductor nanostructure with sub-picosecond resolution. In this study, ultrafast exciton and charge carrier dynamics in GaN/InGaN MQW planar layer and nanorod are investigated using femtosecond transient absorption (TA) techniques at room temperature. Here nanorods are fabricated by etching the GaN/InGaN MQW planar layers using nanosphere lithography and reactive ion etching. Photoluminescence efficiency of the nanorods have been proved to be much higher than that of the planar layers, but the mechanism of the nanorod structure improvement of PL efficiency is not adequately studied. By comparing the TA profile of the GaN/InGaN MQW planar layers and nanorods, the impact of surface states and nanorods lateral confinement in the ultrafast carrier dynamics of GaN/InGaN MQW is revealed. The nanorod sidewall surface states have a strong influence on the InGaN quantum well carrier dynamics. The ultrafast relaxation processes studied in this GaN/InGaN MQW nanostructure is essential for further optimization of device application.

Tribochemical investigation of microelectronic materials

NASA Astrophysics Data System (ADS)

Kulkarni, Milind Sudhakar

To achieve efficient planarization with reduced device dimensions in integrated circuits, a better understanding of the physics, chemistry, and the complex interplay involved in chemical mechanical planarization (CMP) is needed. The CMP process takes place at the interface of the pad and wafer in the presence of the fluid slurry medium. The hardness of Cu is significantly less than the slurry abrasive particles which are usually alumina or silica. It has been accepted that a surface layer can protect the Cu surface from scratching during CMP. Four competing mechanisms in materials removal have been reported: the chemical dissolution of Cu, the mechanical removal through slurry abrasives, the formation of thin layer of Cu oxide and the sweeping surface material by slurry flow. Despite the previous investigation of Cu removal, the electrochemical properties of Cu surface layer is yet to be understood. The motivation of this research was to understand the fundamental aspects of removal mechanisms in terms of electrochemical interactions, chemical dissolution, mechanical wear, and factors affecting planarization. Since one of the major requirements in CMP is to have a high surface finish, i.e., low surface roughness, optimization of the surface finish in reference to various parameters was emphasized. Three approaches were used in this research: in situ measurement of material removal, exploration of the electropotential activation and passivation at the copper surface and modeling of the synergistic electrochemical-mechanical interactions on the copper surface. In this research, copper polishing experiments were conducted using a table top tribometer. A potentiostat was coupled with this tribometer. This combination enabled the evaluation of important variables such as applied pressure, polishing speed, slurry chemistry, pH, materials, and applied DC potential. Experiments were designed to understand the combined and individual effect of electrochemical interactions as well as mechanical impact during polishing. Extensive surface characterization was performed with AFM, SEM, TEM and XPS. An innovative method for direct material removal measurement on the nanometer scale was developed and used. Experimental observations were compared with the theoretically calculated material removal rate values. The synergistic effect of all of the components of the process, which result in a better quality surface finish was quantitatively evaluated for the first time. Impressed potential during CMP proved to be a controlling parameter in the material removal mechanism. Using the experimental results, a model was developed, which provided a practical insight into the CMP process. The research is expected to help with electrochemical material removal in copper planarization with low-k dielectrics.

Signatures of Phonon and Defect-Assisted Tunneling in Planar Metal-Hexagonal Boron Nitride-Graphene Junctions.

PubMed

Chandni, U; Watanabe, K; Taniguchi, T; Eisenstein, J P

2016-12-14

Electron tunneling spectroscopy measurements on van der Waals heterostructures consisting of metal and graphene (or graphite) electrodes separated by atomically thin hexagonal boron nitride tunnel barriers are reported. The tunneling conductance, dI/dV, at low voltages is relatively weak, with a strong enhancement reproducibly observed to occur at around |V| ≈ 50 mV. While the weak tunneling at low energies is attributed to the absence of substantial overlap, in momentum space, of the metal and graphene Fermi surfaces, the enhancement at higher energies signals the onset of inelastic processes in which phonons in the heterostructure provide the momentum necessary to link the Fermi surfaces. Pronounced peaks in the second derivative of the tunnel current, d 2 I/dV 2 , are observed at voltages where known phonon modes in the tunnel junction have a high density of states. In addition, features in the tunneling conductance attributed to single electron charging of nanometer-scale defects in the boron nitride are also observed in these devices. The small electronic density of states of graphene allows the charging spectra of these defect states to be electrostatically tuned, leading to "Coulomb diamonds" in the tunneling conductance.

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

Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas

The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedralmore » shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.« less

Snap evaporation of droplets on smooth topographies.

PubMed

Wells, Gary G; Ruiz-Gutiérrez, Élfego; Le Lirzin, Youen; Nourry, Anthony; Orme, Bethany V; Pradas, Marc; Ledesma-Aguilar, Rodrigo

2018-04-11

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a "stick-slip" sequence-a combination of pinning and de-pinning events dominated by static friction or "pinning", caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications.

Chemical-mechanical polishing of recessed microelectromechanical devices

DOEpatents

Barron, Carole C.; Hetherington, Dale L.; Montague, Stephen

1999-01-01

A method is disclosed for micromachining recessed layers (e.g. sacrificial layers) of a microelectromechanical system (MEMS) device formed in a cavity etched into a semiconductor substrate. The method uses chemical-mechanical polishing (CMP) with a resilient polishing pad to locally planarize one or more of the recessed layers within the substrate cavity. Such local planarization using the method of the present invention is advantageous for improving the patterning of subsequently deposited layers, for eliminating mechanical interferences between functional elements (e.g. linkages) of the MEMS device, and for eliminating the formation of stringers. After the local planarization of one or more of the recessed layers, another CMP step can be provided for globally planarizing the semiconductor substrate to form a recessed MEMS device which can be integrated with electronic circuitry (e.g. CMOS, BiCMOS or bipolar circuitry) formed on the surface of the substrate.

A flexible nanobrush pad for the chemical mechanical planarization of Cu/ultra-low-к materials

PubMed Central

2012-01-01

A new idea of polishing pad called flexible nanobrush pad (FNP) has been proposed for the low down pressure chemical mechanical planarization (CMP) process of Cu/ultra-low-к materials. The FNP was designed with a surface layer of flexible brush-like nanofibers which can ‘actively’ carry nanoscale abrasives in slurry independent of the down pressure. Better planarization performances including high material removal rate, good planarization, good polishing uniformity, and low defectivity are expected in the CMP process under the low down pressure with such kind of pad. The FNP can be made by template-assisted replication or template-based synthesis methods, which will be driven by the development of the preparation technologies for ordered nanostructure arrays. The present work would potentially provide a new solution for the Cu/ultra-low-к CMP process. PMID:23110959

Chemical-mechanical polishing of recessed microelectromechanical devices

DOEpatents

Barron, C.C.; Hetherington, D.L.; Montague, S.

1999-07-06

A method is disclosed for micromachining recessed layers (e.g. sacrificial layers) of a microelectromechanical system (MEMS) device formed in a cavity etched into a semiconductor substrate. The method uses chemical-mechanical polishing (CMP) with a resilient polishing pad to locally planarize one or more of the recessed layers within the substrate cavity. Such local planarization using the method of the present invention is advantageous for improving the patterning of subsequently deposited layers, for eliminating mechanical interferences between functional elements (e.g. linkages) of the MEMS device, and for eliminating the formation of stringers. After the local planarization of one or more of the recessed layers, another CMP step can be provided for globally planarizing the semiconductor substrate to form a recessed MEMS device which can be integrated with electronic circuitry (e.g., CMOS, BiCMOS or bipolar circuitry) formed on the surface of the substrate. 23 figs.

Measurement of six-degree-of-freedom planar motions by using a multiprobe surface encoder

NASA Astrophysics Data System (ADS)

Li, Xinghui; Shimizu, Yuki; Ito, Takeshi; Cai, Yindi; Ito, So; Gao, Wei

2014-12-01

A multiprobe surface encoder for optical metrology of six-degree-of-freedom (six-DOF) planar motions is presented. The surface encoder is composed of an XY planar scale grating with identical microstructures in X- and Y-axes and an optical sensor head. In the optical sensor head, three paralleled laser beams were used as laser probes. After being divided by a beam splitter, the three laser probes were projected onto the scale grating and a reference grating with identical microstructures, respectively. For each probe, the first-order positive and negative diffraction beams along the X- and Y-directions from the scale grating and from the reference grating superimposed with each other and four pieces of interference signals were generated. Three-DOF translational motions of the scale grating Δx, Δy, and Δz can be obtained simultaneously from the interference signals of each probe. Three-DOF angular error motions θX, θY, and θZ can also be calculated simultaneously from differences of displacement output variations and the geometric relationship among the three probes. A prototype optical sensor head was designed, constructed, and evaluated. Experimental results verified that this surface encoder could provide measurement resolutions of subnanometer and better than 0.1 arc sec for three-DOF translational motions and three-DOF angular error motions, respectively.

Space charge limited current measurements on conjugated polymer films using conductive atomic force microscopy.

PubMed

Reid, Obadiah G; Munechika, Keiko; Ginger, David S

2008-06-01

We describe local (~150 nm resolution), quantitative measurements of charge carrier mobility in conjugated polymer films that are commonly used in thin-film transistors and nanostructured solar cells. We measure space charge limited currents (SCLC) through these films using conductive atomic force microscopy (c-AFM) and in macroscopic diodes. The current densities we measure with c-AFM are substantially higher than those observed in planar devices at the same bias. This leads to an overestimation of carrier mobility by up to 3 orders of magnitude when using the standard Mott-Gurney law to fit the c-AFM data. We reconcile this apparent discrepancy between c-AFM and planar device measurements by accounting for the proper tip-sample geometry using finite element simulations of tip-sample currents. We show that a semiempirical scaling factor based on the ratio of the tip contact area diameter to the sample thickness can be used to correct c-AFM current-voltage curves and thus extract mobilities that are in good agreement with values measured in the conventional planar device geometry.

Enhancement of white light OLED efficiency by combining both internal and external light extraction structures

NASA Astrophysics Data System (ADS)

Kao, I.-Ling; Ku, Chun-Neng; Chen, Yi-Ping; Lin, Ding-Zheng

2012-09-01

We proposed an internal nanostructure with a high reflective index planarization layer to solve the optical loss due to the reflective index mismatch between ITO and glass substrate. In our experiments, we found the electrical property of OLED device was significantly influenced by the internal nanostructures without planarization layer. Moreover, the internal extraction structure (IES) is not necessarily beneficial for light extraction. Therefore, we proposed a new substrate combine both internal and external extraction structure (EES) to extract trapping light. We successfully developed a high refractive index (N 1.7) planarization material with flat surface (RMS roughness < 2 nm), and improved about 70% device efficiency compared to traditional glass substrate.

Improved out-coupling efficiency of organic light emitting diodes fabricated on a TiO2 planarization layer with embedded Si oxide nanostructures

NASA Astrophysics Data System (ADS)

Sung, Young Hoon; Jung, Pil-Hoon; Han, Kyung-Hoon; Kim, Yang Doo; Kim, Jang-Joo; Lee, Heon

2017-10-01

In order to increase the out-coupling efficiency of organic light emitting diodes, conical Si oxide nanostructures were formed on a glass substrate using nanoimprint lithography with hydrogen silsesquioxane. Then, the substrate was planarized with TiO2 nanoparticles. Since TiO2 nanoparticles have a higher refractive index than Si oxide, the surface of substrate is physically flat, but optically undulated in a manner that enables optical scattering and suppression of total internal reflection. Subsequently, OLEDs formed on a substrate with nanostructured Si oxide and a TiO2 planarization layer exhibit a 25% increase in out-coupling efficiency by suppressing total internal reflection.

Ultrathin planar hematite film for solar photoelectrochemical water splitting

DOE PAGES

Liu, Dong; Bierman, David M.; Lenert, Andrej; ...

2015-10-08

Hematite holds promise for photoelectrochemical (PEC) water splitting due to its stability, low-cost, abundance and appropriate bandgap. However, it suffers from a mismatch between the hole diffusion length and light penetration length. We have theoretically designed and characterized an ultrathin planar hematite/silver nanohole array/silver substrate photoanode. Due to the supported destructive interference and surface plasmon resonance, photons are efficiently absorbed in an ultrathin hematite film. In conclusion, compared with ultrathin hematite photoanodes with nanophotonic structures, this photoanode has comparable photon absorption but with intrinsically lower recombination losses due to its planar structure and promises to exceed the state-of-the-art photocurrent ofmore » hematite photoanodes.« less

Exact solution of three-dimensional transport problems using one-dimensional models. [in semiconductor devices

NASA Technical Reports Server (NTRS)

Misiakos, K.; Lindholm, F. A.

1986-01-01

Several parameters of certain three-dimensional semiconductor devices including diodes, transistors, and solar cells can be determined without solving the actual boundary-value problem. The recombination current, transit time, and open-circuit voltage of planar diodes are emphasized here. The resulting analytical expressions enable determination of the surface recombination velocity of shallow planar diodes. The method involves introducing corresponding one-dimensional models having the same values of these parameters.

Efficient planar heterojunction perovskite solar cells employing graphene oxide as hole conductor.

PubMed

Wu, Zhongwei; Bai, Sai; Xiang, Jian; Yuan, Zhongcheng; Yang, Yingguo; Cui, Wei; Gao, Xingyu; Liu, Zhuang; Jin, Yizheng; Sun, Baoquan

2014-09-21

Graphene oxide (GO) is employed as a hole conductor in inverted planar heterojunction perovskite solar cells, and the devices with CH₃NH₃PbI₃-xClx as absorber achieve an efficiency of over 12%. The perovskite film grown on GO exhibits enhanced crystallization, high surface coverage ratio as well as preferred in-plane orientation of the (110) plane. Efficient hole extraction from the perovskite to GO is demonstrated.

Planar Solid-Oxide Fuel Cell Research and Development

DTIC Science & Technology

2013-03-28

electrolyte membrane ( PEM ) fuel cells ", Applied Surface Sei., 227 (2004) 56-72. [10] Grujicic, M., and Chittajallu, K. M., "Optimization of the...cathode geometry in polymer electrolyte membrane ( PEM ) fuel cells ", Chem. Eng. Sei., 59 (2004) 5883-5895. 36 [11] Anderson, W.K., Newman, J.C., Whitfield...M., Djilali, N, Suleman, A., "Optimization of a planar self-breathing PEM fuel cell cathode", AIAA 2006-6917, 11th AIAA/ISSMO Multidisciplinary

Influence of pump-field scattering on nonclassical-light generation in a photonic-band-gap nonlinear planar waveguide

NASA Astrophysics Data System (ADS)

Peřina, Jan, Jr.; Sibilia, Concita; Tricca, Daniela; Bertolotti, Mario

2005-04-01

Optical parametric process occurring in a nonlinear planar waveguide can serve as a source of light with nonclassical properties. The properties of the generated fields are substantially modified by scattering of the nonlinearly interacting fields in a photonic-band-gap structure inside the waveguide. A general quantum model of linear operator amplitude corrections to the amplitude mean values and its numerical analysis provide conditions for efficient squeezed-light generation as well as generation of light with sub-Poissonian photon-number statistics. The destructive influence of phase mismatch of the nonlinear interaction can fully be compensated using a suitable photonic-band-gap structure inside the waveguide. Also an increase of the signal-to-noise ratio of the incident optical field can be reached in the waveguide.

Physical mechanism for flat-to-lenticular lens conversion in homogeneous liquid crystal cell with periodically undulated electrode.

PubMed

Na, Jun-Hee; Park, Seung Chul; Kim, Se-Um; Choi, Yoonseuk; Lee, Sin-Doo

2012-01-16

A convertible lenticular liquid crystal (LC) lens architecture is demonstrated using an index-matched planarization layer on a periodically undulated electrode for the homogeneous alignment of an LC. It is found that the in-plane component of the electric field by the undulated electrode plays a primary role in the flat-to-lens effect while the out-of-plane component contributes to the anchoring enhancement of the LC molecules in the surface layer. Our LC device having an index-matched planarization layer on the undulated electrode is capable of achieving the electrical tunability from the flat surface to the lenticular lens suitable for 2D/3D convertible displays.

Organic light emitting diode with surface modification layer

DOEpatents

Basil, John D.; Bhandari, Abhinav; Buhay, Harry; Arbab, Mehran; Marietti, Gary J.

2017-09-12

An organic light emitting diode (10) includes a substrate (12) having a first surface (14) and a second surface (16), a first electrode (32), and a second electrode (38). An emissive layer (36) is located between the first electrode (32) and the second electrode (38). The organic light emitting diode (10) further includes a surface modification layer (18). The surface modification layer (18) includes a non-planar surface (30, 52).

Process for leveling film surfaces and products thereof

DOEpatents

Birkmire, R.W.; McCandless, B.E.

1990-03-20

Semiconductor films and photovoltaic devices prepared therefrom are provided wherein the semiconductor films have a specular surface with a texture less than about 0.25 micron greater than the average planar film surface and wherein the semiconductor films are surface modified by exposing the surface to an aqueous solution of bromine containing an acid or salt and continuing such exposure for a time sufficient to etch the surface. 8 figs.

Tele-autonomous control involving contacts: The applications of a high precision laser line range sensor

NASA Technical Reports Server (NTRS)

Volz, R. A.; Shao, L.; Walker, M. W.; Conway, L. A.

1989-01-01

The object localization algorithm based on line-segment matching is presented. The method is very simple and computationally fast. In most cases, closed-form formulas are used to derive the solution. The method is also quite flexible, because only few surfaces (one or two) need to be accessed (sensed) to gather necessary range data. For example, if the line-segments are extracted from boundaries of a planar surface, only parameters of one surface and two of its boundaries need to be extracted, as compared with traditional point-surface matching or line-surface matching algorithms which need to access at least three surfaces in order to locate a planar object. Therefore, this method is especially suitable for applications when an object is surrounded by many other work pieces and most of the object is very difficult, is not impossible, to be measured; or when not all parts of the object can be reached. The theoretical ground on how to use line range sensor to located an object was laid. Much work has to be done in order to be really useful.

Electromagnetic properties of material coated surfaces

NASA Technical Reports Server (NTRS)

Beard, L.; Berrie, J.; Burkholder, R.; Dominek, A.; Walton, E.; Wang, N.

1989-01-01

The electromagnetic properties of material coated conducting surfaces were investigated. The coating geometries consist of uniform layers over a planar surface, irregularly shaped formations near edges and randomly positioned, electrically small, irregularly shaped formations over a surface. Techniques to measure the scattered field and constitutive parameters from these geometries were studied. The significance of the scattered field from these geometries warrants further study.

Investigations of Optical Properties of Active Regions in Vertical Cavity Surface Emitting Lasers Grown by MBE

DTIC Science & Technology

2002-06-03

Molecular beam epitaxy ; Planar microcavities; Vertical cavity surface emitting lasers 1... Vertical Cavity Surface Emitting Lasers Grown by MBE DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the...S-581 83 Linkiping, Sweden Abstract The design of the vertical cavity surface emitting lasers ( VCSELs ) needs proper tuning of many

Reconstructing the vibro-acoustic quantities on a highly non-spherical surface using the Helmholtz equation least squares method.

PubMed

Natarajan, Logesh Kumar; Wu, Sean F

2012-06-01

This paper presents helpful guidelines and strategies for reconstructing the vibro-acoustic quantities on a highly non-spherical surface by using the Helmholtz equation least squares (HELS). This study highlights that a computationally simple code based on the spherical wave functions can produce an accurate reconstruction of the acoustic pressure and normal surface velocity on planar surfaces. The key is to select the optimal origin of the coordinate system behind the planar surface, choose a target structural wavelength to be reconstructed, set an appropriate stand-off distance and microphone spacing, use a hybrid regularization scheme to determine the optimal number of the expansion functions, etc. The reconstructed vibro-acoustic quantities are validated rigorously via experiments by comparing the reconstructed normal surface velocity spectra and distributions with the benchmark data obtained by scanning a laser vibrometer over the plate surface. Results confirm that following the proposed guidelines and strategies can ensure the accuracy in reconstructing the normal surface velocity up to the target structural wavelength, and produce much more satisfactory results than a straight application of the original HELS formulations. Experiment validations on a baffled, square plate were conducted inside a fully anechoic chamber.

The Electrostatic Screening Length in Concentrated Electrolytes Increases with Concentration.

PubMed

Smith, Alexander M; Lee, Alpha A; Perkin, Susan

2016-06-16

According to classical electrolyte theories interactions in dilute (low ion density) electrolytes decay exponentially with distance, with the Debye screening length the characteristic length scale. This decay length decreases monotonically with increasing ion concentration due to effective screening of charges over short distances. Thus, within the Debye model no long-range forces are expected in concentrated electrolytes. Here we reveal, using experimental detection of the interaction between two planar charged surfaces across a wide range of electrolytes, that beyond the dilute (Debye-Hückel) regime the screening length increases with increasing concentration. The screening lengths for all electrolytes studied-including aqueous NaCl solutions, ionic liquids diluted with propylene carbonate, and pure ionic liquids-collapse onto a single curve when scaled by the dielectric constant. This nonmonotonic variation of the screening length with concentration, and its generality across ionic liquids and aqueous salt solutions, demonstrates an important characteristic of concentrated electrolytes of substantial relevance from biology to energy storage.

Cell adhesion and guidance by micropost-array chemical sensors

NASA Astrophysics Data System (ADS)

Pantano, Paul; Quah, Soo-Kim; Danowski, Kristine L.

2002-06-01

An array of ~50,000 individual polymeric micropost sensors was patterned across a glass coverslip by a photoimprint lithographic technique. Individual micropost sensors were ~3-micrometers tall and ~8-micrometers wide. The O2-sensitive micropost array sensors (MPASs) comprised a ruthenium complex encapsulated in a gas permeable photopolymerizable siloxane. The pH-sensitive MPASs comprised a fluorescein conjugate encapsulated in a photocrosslinkable poly(vinyl alcohol)-based polymer. PO2 and pH were quantitated by acquiring MPAS luminescence images with an epifluorescence microscope/charge coupled device imaging system. O2-sensitive MPASs displayed linear Stern-Volmer quenching behavior with a maximum Io/I of ~8.6. pH-sensitive MPASs displayed sigmoidal calibration curves with a pKa of ~5.8. The adhesion of undifferentiated rat pheochromocytoma (PC12) cells across these two polymeric surface types was investigated. The greatest PC12 cell proliferation and adhesion occurred across the poly(vinyl alcohol)-based micropost arrays relative to planar poly(vinyl alcohol)-based surfaces and both patterned and planar siloxane surfaces. An additional advantage of the patterned MPAS layers relative to planar sensing layers was the ability to direct the growth of biological cells. Preliminary data is presented whereby nerve growth factor-differentiated PC12 cells grew neurite-like processes that extended along paths defined by the micropost architecture.

Simulation, design and fabrication of a planar micro thermoelectric generator

NASA Astrophysics Data System (ADS)

Pelegrini, S.; Adami, A.; Collini, C.; Conci, P.; Lorenzelli, L.; Pasa, A. A.

2013-05-01

This study describes the design, simulation, and micro fabrication of a micro thermoelectric generator (μTEG) based on planar technology using constantan (CuNi) and copper (Cu) thermocouples deposited electrochemically (ECD) on silicon substrate. The present thin film technology can be manufactured into large area and also on flexible substrate with low cost of production and can be used to exploit waste heat from equipments or hot surfaces in general. In the current implementation, the silicon structure has been designed and optimized with analytical models and FE simulations in order to exploit the different thermal conductivity of silicon and air gaps to produce the maximum temperature difference on a planar surface. The results showed that a temperature difference of 10K across the structure creates a temperature difference of 5.3K on the thermocouples, thus providing an efficiency of thermal distribution up to 55%, depending on the heat convection at the surface. Efficiency of module has been experimentally tested under different working condition, showing the dependence of module output on the external heat exchange (natural and forced convection). Maximum generated potential at 6m/s airflow is 5.7V/m2 K and thermoelectric efficiency is 1.9μW K-2 m-2.

Neutral dipole-dipole dimers: A new field in science

NASA Astrophysics Data System (ADS)

Kosower, Edward M.; Borz, Galina

2018-03-01

Dimer formation with dipole neutralization produces species such as low polarity water (LPW) compatible with hydrophobic surfaces (Phys. Chem. Chem. Phys. 2015, 17, 24895-24900) Dimerization and dipole neutralization occurs for N-methylacetamide on polyethylene, a behavior drastically different from its contortions in acetonitrile on AgBr:AgCl planar crystals (AgX) (ChemPhysChem 2014, 15, 3598-3607). The weak infrared absorption of the amide dimer on polyethylene is shown experimentally. Dimerization of palmitic acid is shown along with some of the many ramifications for intracellular systems. Polyoligomers of water are present on polyethylene surfaces. Some high resolution spectra of three of the polyoligomers of water are shown along with a mechanistic scheme for polyoligomer formation and dissolution. The structures of some of the oligomers are known from spectroscopic studies of water on AgX. The scope of the article begins with PE, generally accepted as hydrophobic. The IR of PE revealed not only that water was present but that it appeared in two forms, oligomers (O) and polyoligomers (PO). How did we recognize what they were? These species had been observed as especially strong "marker" peaks in the spectra1 of water placed on planar AgX, a platform developed by Katzir and his coworkers [6]. But there was a problem: the proximity to PE of oligomers with substantial (calculated) dipole moments and thus polarity, including cyclic hexamers of water (chair and boat forms), the cyclic pentamer, the books I and II, and the cyclic trimer [7a]. Another link was needed, a role perfectly fit by the already cited low polarity water (LPW). The choice was experimentally supported by the detection of low intensity absorption in the bending region.Some important generalities flow from these results. What other dimers might be present in the biological or chemical world? Palmitic acid dimer (PAD) would be a candidate for decreasing the polarity of the acid (PA). Another possibility might be N-methylacylamides of which we have noted N-methylacetamide (NMA). We had found that NMA in a polar solvent on AgX was very acrobatic, forming first a 310-helix, an α-helix, a π-helix and a planar form in succession. In sharp contrast, we discovered that NMA forms a dimer (NMAD) and becomes immiscible with the water present on the PE surface. One may vary the acyl group and even include functional groups. Another aspect of the surface behavior of water is the formation of oligomers and polyoligomers. We will show a diagram that explains the formation of polyoligomers from oligomers and their ultimate formation of oligomers with apposed dipoles. This Scope summary should make it easier to follow the description of the varied phenomena found for the PE-water system.

Modeling of Graphene Planar Grating in the THz Range by the Method of Singular Integral Equations

NASA Astrophysics Data System (ADS)

Kaliberda, Mstislav E.; Lytvynenko, Leonid M.; Pogarsky, Sergey A.

2018-04-01

Diffraction of the H-polarized electromagnetic wave by the planar graphene grating in the THz range is considered. The scattering and absorption characteristics are studied. The scattered field is represented in the spectral domain via unknown spectral function. The mathematical model is based on the graphene surface impedance and the method of singular integral equations. The numerical solution is obtained by the Nystrom-type method of discrete singularities.

Modular multi-element high energy particle detector

DOEpatents

Coon, D.D.; Elliott, J.P.

1990-01-02

Multi-element high energy particle detector modules comprise a planar heavy metal carrier of tungsten alloy with planar detector units uniformly distributed over one planar surface. The detector units are secured to the heavy metal carrier by electrically conductive adhesive so that the carrier serves as a common ground. The other surface of each planar detector unit is electrically connected to a feedthrough electrical terminal extending through the carrier for front or rear readout. The feedthrough electrical terminals comprise sockets at one face of the carrier and mating pins projecting from the other face, so that any number of modules may be plugged together to create a stack of modules of any desired number of radiation lengths. The detector units each comprise four, preferably rectangular, p-i-n diode chips arranged around the associated feedthrough terminal to form a square detector unit providing at least 90% detector element coverage of the carrier. Integral spacers projecting from the carriers extend at least partially along the boundaries between detector units to space the p-i-n diode chips from adjacent carriers in a stack. The spacers along the perimeters of the modules are one-half the width of the interior spacers so that when stacks of modules are arranged side by side to form a large array of any size or shape, distribution of the detector units is uniform over the entire array. 5 figs.

Modular multi-element high energy particle detector

DOEpatents

Coon, Darryl D.; Elliott, John P.

1990-01-02

Multi-element high energy particle detector modules comprise a planar heavy metal carrier of tungsten alloy with planar detector units uniformly distributed over one planar surface. The detector units are secured to the heavy metal carrier by electrically conductive adhesive so that the carrier serves as a common ground. The other surface of each planar detector unit is electrically connected to a feedthrough electrical terminal extending through the carrier for front or rear readout. The feedthrough electrical terminals comprise sockets at one face of the carrier and mating pins porjecting from the other face, so that any number of modules may be plugged together to create a stack of modules of any desired number of radiation lengths. The detector units each comprise four, preferably rectangular, p-i-n diode chips arranged around the associated feedthrough terminal to form a square detector unit providing at least 90% detector element coverage of the carrier. Integral spacers projecting from the carriers extend at least partially along the boundaries between detector units to space the p-i-n diode chips from adjacent carriers in a stack. The spacers along the perimeters of the modules are one-half the width of the interior spacers so that when stacks of modules are arranged side by side to form a large array of any size or shape, distribution of the detector units is uniform over the entire array.

Improved fill factor in inverted planar perovskite solar cells with zirconium acetate as the hole-and-ion-blocking layer.

PubMed

Zhang, Xuewen; Liang, Chunjun; Sun, Mengjie; Zhang, Huimin; Ji, Chao; Guo, Zebang; Xu, Yajun; Sun, Fulin; Song, Qi; He, Zhiqun

2018-03-14

Planar perovskite solar cells (PSCs) have gained great interest due to their low-temperature solution preparation and simple process. In inverted planar PSCs, an additional buffer layer is usually needed on the top of the PCBM electron-transport layer (ETL) to enhance the device performance. In this work, we used a new buffer layer, zirconium acetate (Zr(Ac) 4 ). The inclusion of the Zr(Ac) 4 buffer layer leads to the increase of FF from ∼68% to ∼79% and PCE from ∼14% to ∼17% in the planar PSCs. The UPS measurement indicates that the Zr(Ac) 4 layer has a low HOMO level of -8.2 eV, indicating that the buffer layer can act as a hole-blocking layer. Surface morphology and surface chemistry investigations reveal that the elements I, MA and Pb can diffuse across the PCBM ETL, damaging the device performance. The covering Zr(Ac) 4 molecules fill in the pinholes of the PCBM layer and effectively block the ions/molecules of the perovskite from diffusion across the ETL. The resulting more robust PCBM/Zr(Ac) 4 ETL leads to weaker ionic charge accumulation and lower diode leakage current. The double role of hole-and-ion blocking of the Zr(Ac) 4 layer explains the improved FF and PCE in the PSCs.

Optical absorption enhancement in NH2CH=NH2PbI3 lead halide perovskite solar cells with nanotextures

NASA Astrophysics Data System (ADS)

Xie, Ziang; Sun, Shuren; Xie, Xixi; Hou, Ruixiang; Xu, Wanjin; Li, Yanping; Qin, G. G.

2018-01-01

This article reports, for the first time to our knowledge, that the power conversion efficiencies (PCEs) of planar NH2CH=NH2PbI3 (FAPbI3) lead halide perovskite solar cells (SCs) can be largely improved by fabricating nanotextures on the SC surface. Four kinds of nanotextures are investigated and compared with each other: column hollow (CLH) nanoarrays, cone hollow (CNH) nanoarrays, square prism hollow (SPH) nanoarrays, and pyramid hollow (PYH) nanoarrays. Compared with the PCEs of the planar SCs with the same layer depth d, it is found that when d is in the range of 125-500 nm and when the array period, as well as the filling fraction of the nanotexture, are optimized, the ultimate efficiency increased 29%-50% for the CLH and SPH textured FAPbI3 SCs relative to the planar ones, and 20%-41% for the CNH and PYH textured FAPbI3 SCs relative to the planar ones. When d < 250 nm, the optimized ultimate efficiencies of the CLH and SPH textured FAPbI3 SCs with optimized nanotextures are higher than those of the CNH and PYH ones, and vice versa. The reasons why fabricating nanotextures on SC surfaces can largely improve the PCE of the FAPbI3 SCs are discussed.

A new method suitable for calculating accurately wetting temperature over a wide range of conditions: Based on the adaptation of continuation algorithm to classical DFT

NASA Astrophysics Data System (ADS)

Zhou, Shiqi

2017-11-01

A new scheme is put forward to determine the wetting temperature (Tw) by utilizing the adaptation of arc-length continuation algorithm to classical density functional theory (DFT) used originally by Frink and Salinger, and its advantages are summarized into four points: (i) the new scheme is applicable whether the wetting occurs near a planar or a non-planar surface, whereas a zero contact angle method is considered only applicable to a perfectly flat solid surface, as demonstrated previously and in this work, and essentially not fit for non-planar surface. (ii) The new scheme is devoid of an uncertainty, which plagues a pre-wetting extrapolation method and originates from an unattainability of the infinitely thick film in the theoretical calculation. (iii) The new scheme can be similarly and easily applied to extreme instances characterized by lower temperatures and/or higher surface attraction force field, which, however, can not be dealt with by the pre-wetting extrapolation method because of the pre-wetting transition being mixed with many layering transitions and the difficulty in differentiating varieties of the surface phase transitions. (iv) The new scheme still works in instance wherein the wetting transition occurs close to the bulk critical temperature; however, this case completely can not be managed by the pre-wetting extrapolation method because near the bulk critical temperature the pre-wetting region is extremely narrow, and no enough pre-wetting data are available for use of the extrapolation procedure.

Pulsed laser deposited ZnO film on side-polished fiber as a gas sensing element.

PubMed

Dikovska, Anna Og; Atanasov, Petar A; Stoyanchov, Toshko R; Andreev, Andrey T; Karakoleva, Elka I; Zafirova, Blagovesta S

2007-05-01

A simple sensor element consisting of a side-polished single-mode fiber and a planar metal oxide waveguide is described. The thin ZnO planar waveguide was produced on the polished fiber surface by pulsed laser deposition at optimized processing parameters. A measurement scheme for in situ control of the film thickness during the deposition process was developed and used. X-ray diffraction measurements and scanning electron microscopy were used to characterize the structure and the surface morphology of the planar waveguide, respectively. The numerical evaluation of the sensor sensitivity predicts the possibility to detect refractive index changes of less than 10(-4). Furthermore, preliminary gas sensor tests were performed by using a mixture of 1.5% butane diluted in N(2) and pure butane. A shift of the spectral position of the resonance points was observed from 3 to 5 s after gas exposure, which corresponds to refractive index changes of 3 x 10(-5) and 1.2 x 10(-3) for 1.5% butane and for pure butane, respectively.

Highly sensitive surface-scanning detector for the direct bacterial detection using magnetoelastic (ME) biosensors

NASA Astrophysics Data System (ADS)

Liu, Yuzhe; Horikawa, Shin; Chen, I.-Hsuan; Du, Songtao; Wikle, Howard C.; Suh, Sang-Jin; Chin, Bryan A.

2017-05-01

This paper demonstrates a highly sensitive surface-scanning detector used for magnetoelastic (ME) biosensors for the detection of Salmonella on the surface of a polyethylene (PE) food preparation surface. The design and fabrication methods of the new planar spiral coil are introduced. Different concentrations of Salmonella were measured on the surface of a PE board. The efficacy of Salmonella capture and detection is discussed.

Twisted surfaces with vanishing curvature in Galilean 3-space

NASA Astrophysics Data System (ADS)

Dede, Mustafa; Ekici, Cumali; Goemans, Wendy; Ünlütürk, Yasin

In this work, we define twisted surfaces in Galilean 3-space. In order to construct these surfaces, a planar curve is subjected to two simultaneous rotations, possibly with different rotation speeds. The existence of Euclidean rotations and isotropic rotations leads to three distinct types of twisted surfaces in Galilean 3-space. Then we classify twisted surfaces in Galilean 3-space with zero Gaussian curvature or zero mean curvature.

The role of electrostatic charge in the adhesion of spherical particles onto planar surfaces in atmospheric systems

DOE PAGES

Kweon, Hyojin; Yiacoumi, Sotira Z.; Tsouris, Costas

2015-06-19

In this study, the influence of electrostatic charge on the adhesive force between spherical particles and planar surfaces in atmospheric systems was studied using atomic force microscopy. Electrical bias was applied to modify the surface charge, and it was found that application of a stronger positive bias to a particle induces a stronger total adhesive force. The sensitivity of the system to changes in the bias depended on the surface charge density. For larger-size particles, the contribution of the electrostatic force decreased, and the capillary force became the major contributor to the total adhesive force. The influence of water adsorptionmore » on the total adhesive force and, specifically, on the contribution of the electrostatic force depended on the hydrophobicity of interacting surfaces. For a hydrophilic surface, water adsorption either attenuated the surface charge or screened the effect of surface potential. An excessive amount of adsorbed water provided a path to surface charge leakage, which might cancel out the electrostatic force, leading to a reduction in the adhesive force. Theoretically calculated forces were comparable with measured adhesive forces except for mica which has a highly localized surface potential. The results of this study provide information on the behavior of charged colloidal particles in atmospheric systems.« less

Effect of antimony incorporation on the density, shape, and luminescence of InAs quantum dots

NASA Astrophysics Data System (ADS)

Chen, J. F.; Chiang, C. H.; Wu, Y. H.; Chang, L.; Chi, J. Y.

2008-07-01

This work investigates the surfactant effect on exposed and buried InAs quantum dots (QDs) by incorporating Sb into the QD layers with various Sb beam equivalent pressures (BEPs). Secondary ion mass spectroscopy shows the presence of Sb in the exposed and buried QD layers with the Sb intensity in the exposed layer substantially exceeding that in the buried layer. Incorporating Sb can reduce the density of the exposed QDs by more than two orders of magnitude. However, a high Sb BEP yields a surface morphology with a regular periodic structure of ellipsoid terraces. A good room-temperature photoluminescence (PL) at ˜1600 nm from the exposed QDs is observed, suggesting that the Sb incorporation probably improves the emission efficiency by reducing the surface recombination velocity at the surface of the exposed QDs. Increasing Sb BEP causes a blueshift of the emission from the exposed QDs due to a reduction in the dot height as suggested by atomic force microscopy. Increasing Sb BEP can also blueshift the ˜1300 nm emission from the buried QDs by decreasing the dot height. However, a high Sb BEP yields a quantum well-like PL feature formed by the clustering of the buried QDs into an undulated planar layer. These results indicate a marked Sb surfactant effect that can be used to control the density, shape, and luminescence of the exposed and buried QDs.

TiO2 surface functionalization of COC based planar waveguide Bragg gratings for refractive index sensing

NASA Astrophysics Data System (ADS)

Rosenberger, M.; Girschikofsky, M.; Förthner, M.; Belle, S.; Rommel, M.; Frey, L.; Schmauss, B.; Hellmann, R.

2018-01-01

We demonstrate the applicability of a planar waveguide Bragg grating in cyclo-olefin copolymer (COC) for refractive index sensing. The polymer planar waveguide Bragg grating fabricated using a single writing step technique is coated with a high-index layer of titanium dioxide (TiO2) leading to a distinct birefringence. This in turn results in the splitting of the Bragg reflection into two distinct Bragg wavelengths, which strongly differ regarding their refractive index sensitivities. Where one wavelength is only slightly affected by the ambient refractive index, the second Bragg peak shows a strong sensitivity. Furthermore, we investigate the temperature behaviour of the functionalized sensor and discuss it with respect to applications in refractive index sensing.

Customization of a generic 3D model of the distal femur using diagnostic radiographs.

PubMed

Schmutz, B; Reynolds, K J; Slavotinek, J P

2008-01-01

A method for the customization of a generic 3D model of the distal femur is presented. The customization method involves two steps: acquisition of calibrated orthogonal planar radiographs; and linear scaling of the generic model based on the width of a subject's femoral condyles as measured on the planar radiographs. Planar radiographs of seven intact lower cadaver limbs were obtained. The customized generic models were validated by comparing their surface geometry with that of CT-reconstructed reference models. The overall mean error was 1.2 mm. The results demonstrate that uniform scaling as a first step in the customization process produced a base model of accuracy comparable to other models reported in the literature.

Method for surface treatment of a cadmium zinc telluride crystal

DOEpatents

James, Ralph; Burger, Arnold; Chen, Kuo-Tong; Chang, Henry

1999-01-01

A method for treatment of the surface of a CdZnTe (CZT) crystal that reduces surface roughness (increases surface planarity) and provides an oxide coating to reduce surface leakage currents and thereby, improve resolution. A two step process is disclosed, etching the surface of a CZT crystal with a solution of lactic acid and bromine in ethylene glycol, following the conventional bromine/methanol etch treatment, and after attachment of electrical contacts, oxidizing the CZT crystal surface.

Areal Mass Oscillations in Planar Targets Due to Feedout: Theory and Simulations.

NASA Astrophysics Data System (ADS)

Velikovich, A. L.; Schmitt, A. J.; Karasik, M.; Obenschain, S. P.; Serlin, V.; Pawley, C. J.; Gardner, J. H.; Aglitskiy, Y.; Metzler, N.

2001-10-01

When a planar shock wave breaks out at a rippled rear surface of a laser-driven target, the lateral pressure gradient in a rippled rarefaction wave propagating back to the front surface causes a lateral mass redistribution that reverses the phase of mass variation. If the driving laser pulse has no foot, then the RT growth, starting when the rarefaction wave reaches the front surface, causes the second phase reversal of mass variation, and continues at the initial phase, as consistently observed in feedout experiments on Nike. A foot of the laser pulse can cause an early phase reversal of mass variation, making the strong shock wave driven by the main pulse interact with a density variation in a rippled rarefaction wave rather than with static rear surface ripples. Theory and simulations predict that this interaction can make the phase of mass variation reverse one or three times. Then the phase of the RT growing mode would be opposite to that of the initial mass variation.

Immunosensing by luminescence reduction in surface-modified microstructured SU-8

NASA Astrophysics Data System (ADS)

Eravuchira, Pinkie Jacob; Baranowska, Malgorzata; Eckstein, Chris; Díaz, Francesc; Llobet, Eduard; Marsal, Lluis F.; Ferré-Borrull, Josep

2017-01-01

SU-8, an epoxy based negative photoresist is extensively used as a structural material for the fabrication of microelectro-mechanical systems and in microelectronics technology. However, the possible applications of SU-8 for biosensing have not been explored much, mainly because of the photoluminescence SU-8 possesses in the near-UV and visible wavelength ranges which hinders fluorescent labelling of biorecognition events. In this study we demonstrate that photoluminescence of SU-8 can be employed itself as a sensing transduction parameter to produce a tool for immunosensing: the photoluminescence shows a systematic reduction upon modification of its surface chemistry, and in particular upon attachment of an antigen-antibody (aIgG-IgG) pair. We investigate the relation of the amount of reduction of photoluminescence on planar and microstructured surfaces, and we show that microstructuring leads to a higher reduction than a planar surface. Furthermore, we evaluated the dependence of photoluminescence reduction as a function of analyte concentration to prove that this magnitude can be applied to immunosensing.

Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces

DOE PAGES

Kaghazchi, Payam; Jacob, Timo; Chen, Wenhua; ...

2013-06-03

Here, we report adsorption and desorption of hydrogen on planar Ir(210) and faceted Ir(210), consisting of nanoscale {311} and (110) facets, by means of temperature programmed desorption (TPD) and density functional theory (DFT) in combination with the ab initio atomistic thermodynamics approach. TPD spectra show that only one H 2 peak is seen from planar Ir(210) at all coverages whereas a single H 2 peak is observed at around 440 K (F1) at fractional monolayer (ML) coverage and an additional H 2 peak appears at around 360 K (F2) at 1 ML coverage on faceted Ir(210), implying structure sensitivity inmore » recombination and desorption of hydrogen on faceted Ir(210) versus planar Ir(210), but no evidence is found for size effects in recombination and desorption of hydrogen on faceted Ir(210) for average facet sizes of 5-14 nm. Calculations indicate that H prefers to bind at the two-fold short-bridge sites of the Ir surfaces. In addition, we studied the stability of the Ir surfaces in the presence of hydrogen at different H coverages through surface free energy plots as a function of the chemical potential, which is also converted to a temperature scale. Moreover, the calculations revealed the origin of the two TPD peaks of H 2 from faceted Ir(210): F1 from desorption of H 2 on {311} facets while F2 from desorption of H 2 on (110) facets.« less

Ge nanopillar solar cells epitaxially grown by metalorganic chemical vapor deposition

PubMed Central

Kim, Youngjo; Lam, Nguyen Dinh; Kim, Kangho; Park, Won-Kyu; Lee, Jaejin

2017-01-01

Radial junction solar cells with vertically aligned wire arrays have been widely studied to improve the power conversion efficiency. In this work, we report the first Ge nanopillar solar cell. Nanopillar arrays are selectively patterned on p-type Ge (100) substrates using nanosphere lithography and deep reactive ion etching processes. Nanoscale radial and planar junctions are realized by an n-type Ge emitter layer which is epitaxially grown by MOCVD using isobutylgermane. In situ epitaxial surface passivation is employed using an InGaP layer to avoid high surface recombination rates and Fermi level pinning. High quality n-ohmic contact is realized by protecting the top contact area during the nanopillar patterning. The short circuit current density and the power conversion efficiency of the Ge nanopillar solar cell are demonstrated to be improved up to 18 and 30%, respectively, compared to those of the Ge solar cell with a planar surface. PMID:28209964

Planar integrated metasurfaces for highly-collimated terahertz quantum cascade lasers

PubMed Central

Liang, Guozhen; Dupont, Emmanuel; Fathololoumi, Saeed; Wasilewski, Zbigniew R.; Ban, Dayan; Liang, Hou Kun; Zhang, Ying; Yu, Siu Fung; Li, Lianhe H.; Davies, Alexander Giles; Linfield, Edmund H.; Liu, Hui Chun; Wang, Qi Jie

2014-01-01

We report planar integration of tapered terahertz (THz) frequency quantum cascade lasers (QCLs) with metasurface waveguides that are designed to be spoof surface plasmon (SSP) out-couplers by introducing periodically arranged SSP scatterers. The resulting surface-emitting THz beam profile is highly collimated with a divergence as narrow as ~4° × 10°, which indicates a good waveguiding property of the metasurface waveguide. In addition, the low background THz power implies a high coupling efficiency for the THz radiation from the laser cavity to the metasurface structure. Furthermore, since all the structures are in-plane, this scheme provides a promising platform where well-established surface plasmon/metasurface techniques can be employed to engineer the emitted beam of THz QCLs controllably and flexibly. More importantly, an integrated active THz photonic circuit for sensing and communication applications could be constructed by incorporating other optoelectronic devices such as Schottky diode THz mixers, and graphene modulators and photodetectors. PMID:25403796

Large area planar stanene epitaxially grown on Ag(1 1 1)

NASA Astrophysics Data System (ADS)

Yuhara, Junji; Fujii, Yuya; Nishino, Kazuki; Isobe, Naoki; Nakatake, Masashi; Xian, Lede; Rubio, Angel; Le Lay, Guy

2018-04-01

Artificial post-graphene elemental 2D materials have received much attention recently. Especially, stanene, the tin analogue of graphene, is expected to be a robust 2D topological insulator, even above room temperature. We have grown epitaxial 2D stanene on a Ag(1 1 1) single crystal template and determined its crystalline structure synergetically by scanning tunneling microscopy, high-resolution synchrotron radiation photoemission spectroscopy, and advanced first principles calculations. From the STM images, we show that stanene forms a nearly planar structure in large domains. A detailed core-level spectroscopy analysis as well as DFT calculations reveal that the stanene sheet lays over an ordered 2D Ag2Sn surface alloy, but not directly on a bulk-terminated Ag(1 1 1) surface. The electronic structure exhibits a characteristic 2D band with parabolic dispersion due to the non-negligible interaction with the underlying surface alloy.

Improvement of GaN light-emitting diodes with surface-treated Al-doped ZnO transparent Ohmic contacts by holographic photonic crystal

NASA Astrophysics Data System (ADS)

Yang, W. F.; Liu, Z. G.; Xie, Y. N.; Cai, J. F.; Liu, S.; Gong, H.; Wu, Z. Y.

2012-06-01

This letter presents a holographic photonic crystal (H-PhC) Al-doped ZnO (AZO) transparent Ohmic contact layer on p-GaN to increase the light output of GaN-based LEDs without destroying the p-GaN. The operating voltage of the PhC LEDs at 20 mA was almost the same as that of the typical planar AZO LEDs. While the resultant PhC LED devices exhibited significant improvements in light extraction, up to 1.22 times that of planar AZO LEDs without PhC integration. Temperature dependence of the integrated photoluminescence intensity indicates that this improvement can be attributed to the increased extraction efficiency due to the surface modification. These results demonstrate that the surface-treated AZO layer by H-PhCs is suitable for fabricating high-brightness GaN-based LEDs.

Dolomitization and neomorphism of Mississippian (Visean) upper debolt formation, Blueberry field, northeastern British Columbia: Geologic, petrologic, and chemical evidence

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

Durocher, S.; Al-Aasm, I.S.

1997-06-01

Petrographic, chemical, and isotopic studies of the Mississippian (Visean) upper Debolt Formation in the Blueberry field, British Columbia, Canada, reveal that dolomitization was the result of several diagenetic events and that neomorphic alteration of these dolomites significantly modified their original chemical signatures. These studies also demonstrate how tectonics play an important role in controlling and modifying reservoir dolomites in the area. Petrographic investigations have documented two early dolomite phases, (1) early matrix dolomite and (2) pervasive dolomite, and two later generations, (3) coarse cement and (4) pseudomorphic replacement of crinoids. Early matrix dolomite occurs as small (average 25 {mu}m) subhedralmore » to euhedral crystals that replace the matrix of carbonate mudstones, wackestones, and packstones. Petrographic evidence suggests that early matrix dolomite had a relatively early, precompaction origin, possibly from marine fluids. However, geochemical evidence indicates that later fluids have altered their original geochemical signatures. Pervasive dolomite, which forms the reservoir intercrystalline porosity, occurs with planar-s and planar-e textures. Planar-s crystals typically have a dirty appearance and exhibit homogeneous dull brown/red cathodoluminescence colors. Planar-e crystals may appear with a cloudy core and a clear rim, and under cathodoluminescence display an irregular dull brown/red core and a thin, bright red rim. Due to the spatial distribution pattern of pervasive dolomite with respect to the overlying unconformity surface, its paleogeographic distribution and close temporal relationship with meteoric diagenetic events, pervasive dolomite formed from a mixture of seawater and meteoric fluids. However, alteration of their primary chemistry by later fluids is indicated by their depleted {delta}{sup 18}O values and radiogenic {sup 87}Sr/{sup 86}Sr ratios.« less

Excretion pattern of co-planar and non-planar tetra- and hexa-chlorobiphenyls in ovine milk and faeces

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

Vrecl, Milka; Ursic, Matjaz; Pogacnik, Azra

This study employed the gas chromatography with electron capture detection to determine residual levels and excretion patterns of two pairs of structurally diverse polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 54, 80, 155, and 169) administered to lactating sheep by intramuscular injection. PCB levels and excretion patterns in blood, milk, and faeces were time-dependent and differed from the composition of PCB congeners administered. Lactational transfer substantially exceeded the faecal transfer. Between days 3 and 7, the amount of PCB congeners 54 and 169 excreted in milk was around 50- and 800-fold higher than the amount of these two congeners excreted viamore » faeces. During the same period, the relative contribution of co-planar PCB congeners (80 and 169) in PCB pattern decreased in blood and increased in milk and faeces compared with non-planar PCBs (54 and 155). On day 3, the ratio PCB 169 to 54 was 7-fold higher in milk than in faeces. PCB congeners with log K{sub ow} values under 6.5 reached peaks of their excretion in milk within the first three days after administration, while the super-lipophilic PCB 169 congener with log K{sub ow} value of over 7 has not reached the plateau until day 10, but afterwards, its level remained relatively high throughout the observation period. During the 57-day follow-up period, the excretion of PCB 80, 155, and 169 in milk was 4.5-, 14-, and 46-fold greater compared with PCB 54. Differences in levels and patterns were explained with some physico-chemical properties of individual PCB congeners, such as lipophilicity, planarity, metabolic stability, sorption/diffusion properties.« less

Planar microlens with front-face angle: design, fabrication, and characterization

NASA Astrophysics Data System (ADS)

Al Hafiz, Md. Abdullah; Michael, Aron; Kwok, Chee-Yee

2016-07-01

This paper studies the effect of microlens front-face angle on the performance of an optical system consisting of a planar-graded refractive index (GRIN) lens pair facing each other separated by a free-space region. The planar silica microlens pairs are designed to facilitate low-loss optical signal propagation in the free-space region between the opposing optical waveguides. The planar lens is fabricated from a 38-μm-thick fluorine-doped silica layer on a silicon substrate. It has a parabolic refractive index profile in the vertical direction, which is achieved by controlled fluorine incorporation in the silica film to collimate the optical beam in the vertical direction. Horizontal beam collimation is achieved by incorporating a horizontal curvature at the front face of the lens defined by deep oxide etch. A generalized 3×3 ABCDGH transformation matrix method has been derived to compute the coupling efficiency of such microlens pairs to take front-face angles that may be present due to fabrication variations or limitations and possible input/output optical fiber offset/tilt into considerations. Pairs of such planar GRIN lens with various free-space propagation distances between them ranging from 75 to 2500 μm and with front-face angles of 1.5 deg, 2 deg, and 4 deg have been fabricated and characterized. Beam propagation method simulations have been carried out to substantiate the theoretical and experimental results. The results indicate that the optical loss is reasonably low up to 1.5 deg of front-face angles and increases significantly with further increase in the front-face angle. Analysis shows that for a given system with specific microlens front-face angle, the optical loss can be significantly reduced by properly compensating the vertical position of the input and output fibers.

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

DOE PAGES

Shen, Youde; Chen, Renjie; Yu, Xuechao; ...

2016-06-02

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor–liquid–solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. In this paper, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs–Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed tomore » impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs–Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. Finally, these results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices.« less

Gibbs-Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth.

PubMed

Shen, Youde; Chen, Renjie; Yu, Xuechao; Wang, Qijie; Jungjohann, Katherine L; Dayeh, Shadi A; Wu, Tom

2016-07-13

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices.

Cholesteric pitch transitions induced by mechanical strain.

PubMed

Lelidis, I; Barbero, G; Alexe-Ionescu, A L

2013-02-01

We investigate thickness and surface anchoring strength influence on pitch transitions in a planar cholesteric liquid crystal layer. The cholesteric-nematic transition is also investigated. We assume planar boundary conditions, with strong anchoring strength at one interface and weak anchoring strength at the other. The surface anchoring energy we consider to describe the deviation of the surface twist angle from the easy axis induced by a bulk deformation is a parabolic potential or Rapini and Papoular periodic potential, respectively. We show that under strain, all pitch transitions take place at a critical thickness that is equal to the quarter of the natural cholesteric pitch. The latter result does not depend on the anchoring strength, the particular surface potential, or material properties. The twist angle on the limiting surface characterized by weak anchoring varies with strain either by slipping and or in a discontinuous manner according to the thickness of the sample. The position of the bifurcation point depends only on the ratio of the extrapolation length over the layer thickness, but its value is model dependent. Multistability and multiplicity of the transition are discussed.

Quasi-optical theory of relativistic surface-wave oscillators with one-dimensional and two-dimensional periodic planar structures

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

Ginzburg, N. S.; Zaslavsky, V. Yu.; Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950

2013-11-15

Within the framework of a quasi-optical approach, we develop 2D and 3D self-consistent theory of relativistic surface-wave oscillators. Presenting the radiation field as a sum of two counter-propagating wavebeams coupled on a shallow corrugated surface, we describe formation of an evanescent slow wave. Dispersion characteristics of the evanescent wave following from this method are in good compliance with those found from the direct cst simulations. Considering excitation of the slow wave by a sheet electron beam, we simulate linear and nonlinear stages of interaction, which allows us to determine oscillation threshold conditions, electron efficiency, and output coupling. The transition frommore » the model of surface-wave oscillator operating in the π-mode regime to the canonical model of relativistic backward wave oscillator is considered. We also described a modified scheme of planar relativistic surface-wave oscillators exploiting two-dimensional periodic gratings. Additional transverse propagating waves emerging on these gratings synchronize the emission from a wide sheet rectilinear electron beam allowing realization of a Cherenkov millimeter-wave oscillators with subgigawatt output power level.« less

Topological surface states interacting with bulk excitations in the Kondo insulator SmB6 revealed via planar tunneling spectroscopy.

PubMed

Park, Wan Kyu; Sun, Lunan; Noddings, Alexander; Kim, Dae-Jeong; Fisk, Zachary; Greene, Laura H

2016-06-14

Samarium hexaboride (SmB6), a well-known Kondo insulator in which the insulating bulk arises from strong electron correlations, has recently attracted great attention owing to increasing evidence for its topological nature, thereby harboring protected surface states. However, corroborative spectroscopic evidence is still lacking, unlike in the weakly correlated counterparts, including Bi2Se3 Here, we report results from planar tunneling that unveil the detailed spectroscopic properties of SmB6 The tunneling conductance obtained on the (001) and (011) single crystal surfaces reveals linear density of states as expected for two and one Dirac cone(s), respectively. Quite remarkably, it is found that these topological states are not protected completely within the bulk hybridization gap. A phenomenological model of the tunneling process invoking interaction of the surface states with bulk excitations (spin excitons), as predicted by a recent theory, provides a consistent explanation for all of the observed features. Our spectroscopic study supports and explains the proposed picture of the incompletely protected surface states in this topological Kondo insulator SmB6.

Topological surface states interacting with bulk excitations in the Kondo insulator SmB6 revealed via planar tunneling spectroscopy

PubMed Central

Park, Wan Kyu; Sun, Lunan; Noddings, Alexander; Kim, Dae-Jeong; Fisk, Zachary; Greene, Laura H.

2016-01-01

Samarium hexaboride (SmB6), a well-known Kondo insulator in which the insulating bulk arises from strong electron correlations, has recently attracted great attention owing to increasing evidence for its topological nature, thereby harboring protected surface states. However, corroborative spectroscopic evidence is still lacking, unlike in the weakly correlated counterparts, including Bi2Se3. Here, we report results from planar tunneling that unveil the detailed spectroscopic properties of SmB6. The tunneling conductance obtained on the (001) and (011) single crystal surfaces reveals linear density of states as expected for two and one Dirac cone(s), respectively. Quite remarkably, it is found that these topological states are not protected completely within the bulk hybridization gap. A phenomenological model of the tunneling process invoking interaction of the surface states with bulk excitations (spin excitons), as predicted by a recent theory, provides a consistent explanation for all of the observed features. Our spectroscopic study supports and explains the proposed picture of the incompletely protected surface states in this topological Kondo insulator SmB6. PMID:27233936

Generalized Boussinesq-Scriven surface fluid model with curvature dissipation for liquid surfaces and membranes.

PubMed

Aguilar Gutierrez, Oscar F; Herrera Valencia, Edtson E; Rey, Alejandro D

2017-10-01

Curvature dissipation is relevant in synthetic and biological processes, from fluctuations in semi-flexible polymer solutions, to buckling of liquid columns, tomembrane cell wall functioning. We present a micromechanical model of curvature dissipation relevant to fluid membranes and liquid surfaces based on a parallel surface parameterization and a stress constitutive equation appropriate for anisotropic fluids and fluid membranes.The derived model, aimed at high curvature and high rate of change of curvature in liquid surfaces and membranes, introduces additional viscous modes not included in the widely used 2D Boussinesq-Scriven rheological constitutive equation for surface fluids.The kinematic tensors that emerge from theparallel surface parameterization are the interfacial rate of deformation and the surface co-rotational Zaremba-Jaumann derivative of the curvature, which are used to classify all possibledissipative planar and non-planar modes. The curvature dissipation function that accounts for bending, torsion and twist rates is derived and analyzed under several constraints, including the important inextensional bending mode.A representative application of the curvature dissipation model to the periodic oscillation in nano-wrinkled outer hair cells show how and why curvature dissipation decreases with frequency, and why the 100kHz frequency range is selected. These results contribute to characterize curvature dissipation in membranes and liquid surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

Frontside-micromachined planar piezoresistive vibration sensor: Evaluating performance in the low frequency test range

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

Zhang, Lan; Lu, Jian, E-mail: jian-lu@aist.go.jp; Takagi, Hideki

2014-01-15

Using a surface piezoresistor diffusion method and front-side only micromachining process, a planar piezoresistive vibration sensor was successfully developed with a simple structure, lower processing cost and fewer packaging difficulties. The vibration sensor had a large sector proof mass attached to a narrow flexure. Optimization of the boron diffusion piezoresistor placed on the edge of the narrow flexure greatly improved the sensitivity. Planar vibration sensors were fabricated and measured in order to analyze the effects of the sensor dimensions on performance, including the values of flexure width and the included angle of the sector. Sensitivities of fabricated planar sensors ofmore » 0.09–0.46 mV/V/g were measured up to a test frequency of 60 Hz. The sensor functioned at low voltages (<3 V) and currents (<1 mA) with a high sensitivity and low drift. At low background noise levels, the sensor had performance comparable to a commercial device.« less

CH₃NH₃PbI₃-based planar solar cells with magnetron-sputtered nickel oxide.

PubMed

Cui, Jin; Meng, Fanping; Zhang, Hua; Cao, Kun; Yuan, Huailiang; Cheng, Yibing; Huang, Feng; Wang, Mingkui

2014-12-24

Herein we report an investigation of a CH3NH3PbI3 planar solar cell, showing significant power conversion efficiency (PCE) improvement from 4.88% to 6.13% by introducing a homogeneous and uniform NiO blocking interlayer fabricated with the reactive magnetron sputtering method. The sputtered NiO layer exhibits enhanced crystallization, high transmittance, and uniform surface morphology as well as a preferred in-plane orientation of the (200) plane. The PCE of the sputtered-NiO-based perovskite p-i-n planar solar cell can be further promoted to 9.83% when a homogeneous and dense perovskite layer is formed with solvent-engineering technology, showing an impressive open circuit voltage of 1.10 V. This is about 33% higher than that of devices using the conventional spray pyrolysis of NiO onto a transparent conducting glass. These results highlight the importance of a morphology- and crystallization-compatible interlayer toward a high-performance inverted perovskite planar solar cell.

1.5-μm high-average power laser amplifier using a Er,Yb:glass planar waveguide for coherent Doppler lidar

NASA Astrophysics Data System (ADS)

Sakimura, Takeshi; Watanabe, Yojiro; Ando, Toshiyuki; Kameyama, Shumpei; Asaka, Kimio; Tanaka, Hisamichi; Yanagisawa, Takayuki; Hirano, Yoshihito; Inokuchi, Hamaki

2012-11-01

We have developed a 1.5-μm eye-safe wavelength high average power laser amplifier using an Er,Yb:glass planar waveguide for coherent Doppler LIDAR. Large cooling surface of the planar waveguide enabled high average power pumping for Er,Yb:glass which has low thermal fracture limit. Nonlinear effects are suppressed by the large beam size which is designed by the waveguide thickness and the beam width of the planar direction. Multi-bounce optical path configuration and high-intensity pumping provide high-gain and high-efficient operation using three-level laser material. With pulsed operation, the maximum pulse energy of 1.9 mJ was achieved at the repetition rate of 4 kHz. Output average power of the amplified signal was 7.6W with the amplified gain of more than 20dB. This amplifier is suitable for coherent Doppler LIDAR to enhance the measurable range.

Planar oscillatory stirring apparatus

NASA Technical Reports Server (NTRS)

Wolf, Martin F. (Inventor)

1987-01-01

Apparatus (11) for applying planar oscillations to a container (13). Pressurized air (99) is supplied to a moveable slide plate (27) which employs arms (19) having an air bearing vent structure (29, 31) which allows the slide plate to float and to translate. The container (13) to be oscillated is secured to the upper surface of the slide plate (27). A motor (39) driven rotating eccentric shaft (59) loosely extends into a center hole bearing (37) of the slide plate (27) to cause the oscillations.

Highly-dispersive electromagnetic induced transparency in planar symmetric metamaterials.

PubMed

Lu, Xiqun; Shi, Jinhui; Liu, Ran; Guan, Chunying

2012-07-30

We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation.

Fine woody fuel particle diameters for improved planar intersect fuel loading estimates in Southern Rocky Mountain ponderosa pine forests

Treesearch

Emma Vakili; Chad M. Hoffman; Robert E. Keane

2016-01-01

Fuel loading estimates from planar intersect sampling protocols for fine dead down woody surface fuels require an approximation of the mean squared diameter (d2) of 1-h (0-0.63 cm), 10-h (0.63-2.54 cm), and 100-h (2.54-7.62 cm) timelag size classes. The objective of this study is to determine d2 in ponderosa pine (Pinus ponderosa) forests of New Mexico and Colorado,...

[Optical Design of Miniature Infrared Gratings Spectrometer Based on Planar Waveguide].

PubMed

Li, Yang-yu; Fang, Yong-hua; Li, Da-cheng; Liu, Yang

2015-03-01

In order to miniaturize an infrared spectrometer, we analyze the current optical design of miniature spectrometers and propose a method for designing a miniature infrared gratings spectrometer based on planar waveguide. Common miniature spectrometer uses miniature optical elements to reduce the size of system, which also shrinks the effective aperture. So the performance of spectrometer has dropped. Miniaturization principle of planar waveguide spectrometer is different from the principle of common miniature spectrometer. In planar waveguide spectrometer, the propagation of light is limited in a thin planar waveguide, which looks like the whole optical system is squashed flat. In the direction parallel to the planar waveguide, the light through the slit is collimated, dispersed and focused. And a spectral image is formed in the detector plane. This propagation of light is similar to the light in common miniature spectrometer. In the direction perpendicular to the planar waveguide, light is multiple reflected by the upper and lower surfaces of the planar waveguide and propagates in the waveguide. So the size of corresponding optical element could be very small in the vertical direction, which can reduce the size of the optical system. And the performance of the spectrometer is still good. The design method of the planar waveguide spectrometer can be separated into two parts, Czerny-Turner structure design and planar waveguide structure design. First, by using aberration theory an aberration-corrected (spherical aberration, coma, focal curve) Czerny-Turner structure is obtained. The operation wavelength range and spectral resolution are also fixed. Then, by using geometrical optics theory a planar waveguide structure is designed for reducing the system size and correcting the astigmatism. The planar waveguide structure includes a planar waveguide and two cylindrical lenses. Finally, they are modeled together in optical design software and are optimized as a whole. An infrared planar waveguide spectrometer is designed using this method. The operation wavelength range is 8 - 12 μm, the numerical aperture is 0.22, and the linear array detector contains 64 elements. By using Zemax software, the design is optimized and analyzed. The results indicate that the size of the optical system is 130 mm x 125 mm x 20 mm and the spectral resolution of spectrometer is 80 nm, which satisfy the requirements of design index. Thus it is this method that can be used for designing a miniature spectrometer without movable parts and sizes in the range of several cubic centimeters.

Approach to high quality GaN lateral nanowires and planar cavities fabricated by focused ion beam and metal-organic vapor phase epitaxy.

PubMed

Pozina, Galia; Gubaydullin, Azat R; Mitrofanov, Maxim I; Kaliteevski, Mikhail A; Levitskii, Iaroslav V; Voznyuk, Gleb V; Tatarinov, Evgeniy E; Evtikhiev, Vadim P; Rodin, Sergey N; Kaliteevskiy, Vasily N; Chechurin, Leonid S

2018-05-08

We have developed a method to fabricate GaN planar nanowires and cavities by combination of Focused Ion Beam (FIB) patterning of the substrate followed by Metal Organic Vapor Phase Epitaxy (MOVPE). The method includes depositing a silicon nitride mask on a sapphire substrate, etching of the trenches in the mask by FIB with a diameter of 40 nm with subsequent MOVPE growth of GaN within trenches. It was observed that the growth rate of GaN is substantially increased due to enhanced bulk diffusion of the growth precursor therefore the model for analysis of the growth rate was developed. The GaN strips fabricated by this method demonstrate effective luminescence properties. The structures demonstrate enhancement of spontaneous emission via formation of Fabry-Perot modes.

Broadband Ultrasonic Transducers

NASA Technical Reports Server (NTRS)

Heyser, R. C.

1986-01-01

New geometry spreads out resonance region of piezoelectric crystal. In new transducer, crystal surfaces made nonparallel. One surface planar; other, concave. Geometry designed to produce nearly uniform response over a predetermined band of frequencies and to attenuate strongly frequencies outside band. Greater bandwidth improves accuracy of sonar and ultrasonic imaging equipment.

Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces

NASA Astrophysics Data System (ADS)

Rathsam, Jonathan

This dissertation seeks to advance the current state of computer-based sound field simulations for room acoustics. The first part of the dissertation assesses the reliability of geometric sound-field simulations, which are approximate in nature. The second part of the dissertation uses the rigorous boundary element method (BEM) to learn more about reflections from finite reflectors: planar and non-planar. Acoustical designers commonly use geometric simulations to predict sound fields quickly. Geometric simulation of reflections from rough surfaces is still under refinement. The first project in this dissertation investigates the scattering coefficient, which quantifies the degree of diffuse reflection from rough surfaces. The main result is that predicted reverberation time varies inversely with scattering coefficient if the sound field is nondiffuse. Additional results include a flow chart that enables acoustical designers to gauge how sensitive predicted results are to their choice of scattering coefficient. Geometric acoustics is a high-frequency approximation to wave acoustics. At low frequencies, more pronounced wave phenomena cause deviations between real-world values and geometric predictions. Acoustical designers encounter the limits of geometric acoustics in particular when simulating the low frequency response from finite suspended reflector panels. This dissertation uses the rigorous BEM to develop an improved low-frequency radiation model for smooth, finite reflectors. The improved low frequency model is suggested in two forms for implementation in geometric models. Although BEM simulations require more computation time than geometric simulations, BEM results are highly accurate. The final section of this dissertation uses the BEM to investigate the sound field around non-planar reflectors. The author has added convex edges rounded away from the source side of finite, smooth reflectors to minimize coloration of reflections caused by interference from boundary waves. Although the coloration could not be fully eliminated, the convex edge increases the sound energy reflected into previously nonspecular zones. This excess reflected energy is marginally audible using a standard of 20 dB below direct sound energy. The convex-edged panel is recommended for use when designers want to extend reflected energy spatially beyond the specular reflection zone of a planar panel.

Plant-mediated Sediment Oxygenation in Coastal Wetlands

NASA Astrophysics Data System (ADS)

Koop-Jakobsen, K.

2016-02-01

Belowground sediment oxygenation by wetland plants is an important mechanism controlling many microbial processes and chemical fluxes in coastal wetlands. Although transport of oxygen via the arenthyma tissue and subsequent oxygen loss across root surfaces is well-documented for Spartina grasses, only few studies have measured the oxygenation of sediment surrounding roots and rhizomes. In this study, the degree of sediment oxygenation in Spartina anglica rhizospheres was assessed in situ using a novel multifiber optode system inserting 100 oxygen sensing fiber optodes directly into the rhizosphere. Two closely located, but morphologically different, S. anglica populations growing in permeable sandy sediment and tidal flat deposit, respectively, were investigated. No oxygen was detected inside the rhizospheres at any depth in either location indicating that plant-mediated sediment oxygenation in S. anglica had a limited impact on the bulk anoxic sediment. This was substantiated by planar optode studies showing that sediment oxygenation was confined to the immediate vicinity of the root tips of adventitious root and root hairs stretching only up to 1.5mm away from the roots surface in permeable sandy sediment and 0.4mm in tidal flat deposit, which had a substantially higher oxygen demand. This contrasts previous studies estimating that more than half of the S. anglica rhizosphere volume may be oxygenated, and thereby suggests a high variability in the degree of sediment oxygenation among different S. anglica populations. Furthermore, there may be a significant difference in the degree of sediment oxygenation among different Spartina species; our recent in situ investigation of oxygen profiles in a Spartina alterniflora-dominated marsh suggested that oxygen leakage here may keep the bulk sediment at low oxygen concentration ranging from 0.5-4μM.

Solar concentrator

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

Melchior, B.

1984-04-03

A solar concentrator comprises a solid block of a transparent material having a planar incident surface positioned to receive solar rays and, opposite this surface, a curved reflective surface so that the material of the block completely fills the space between these surfaces. At the incident surface an absorber is provided and the curvature of the reflective surface is such that it is at least partly parabolical and adapted to reflect solar rays traversing the body through the body again to the absorber.

Synthesis, Surface Studies, Composition and Structural Characterization of CdSe, Core/Shell, and Biologically Active Nanocrystals

PubMed Central

Rosenthal, Sandra J.; McBride, James; Pennycook, Stephen J.; Feldman, Leonard C.

2011-01-01

Nanostructures, with their very large surface to volume ratio and their non-planar geometry, present an important challenge to surface scientists. New issues arise as to surface characterization, quantification and interface formation. This review summarizes the current state of the art in the synthesis, composition, surface and interface control of CdSe nanocrystal systems, one of the most studied and useful nanostructures. PMID:21479151

Method for surface treatment of a cadmium zinc telluride crystal

DOEpatents

James, R.; Burger, A.; Chen, K.T.; Chang, H.

1999-08-03

A method for treatment of the surface of a CdZnTe (CZT) crystal is disclosed that reduces surface roughness (increases surface planarity) and provides an oxide coating to reduce surface leakage currents and thereby, improve resolution. A two step process is disclosed, etching the surface of a CZT crystal with a solution of lactic acid and bromine in ethylene glycol, following the conventional bromine/methanol etch treatment, and after attachment of electrical contacts, oxidizing the CZT crystal surface. 3 figs.

A fracture mechanics study of the phase separating planar electrodes: Phase field modeling and analytical results

NASA Astrophysics Data System (ADS)

Haftbaradaran, H.; Maddahian, A.; Mossaiby, F.

2017-05-01

It is well known that phase separation could severely intensify mechanical degradation and expedite capacity fading in lithium-ion battery electrodes during electrochemical cycling. Experiments have frequently revealed that such degradation effects could be substantially mitigated via reducing the electrode feature size to the nanoscale. The purpose of this work is to present a fracture mechanics study of the phase separating planar electrodes. To this end, a phase field model is utilized to predict how phase separation affects evolution of the solute distribution and stress profile in a planar electrode. Behavior of the preexisting flaws in the electrode in response to the diffusion induced stresses is then examined via computing the time dependent stress intensity factor arising at the tip of flaws during both the insertion and extraction half-cycles. Further, adopting a sharp-interphase approximation of the system, a critical electrode thickness is derived below which the phase separating electrode becomes flaw tolerant. Numerical results of the phase field model are also compared against analytical predictions of the sharp-interphase model. The results are further discussed with reference to the available experiments in the literature. Finally, some of the limitations of the model are cautioned.

Limitations to the use of two-dimensional thermal modeling of a nuclear waste repository

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

Davis, B.W.

1979-01-04

Thermal modeling of a nuclear waste repository is basic to most waste management predictive models. It is important that the modeling techniques accurately determine the time-dependent temperature distribution of the waste emplacement media. Recent modeling studies show that the time-dependent temperature distribution can be accurately modeled in the far-field using a 2-dimensional (2-D) planar numerical model; however, the near-field cannot be modeled accurately enough by either 2-D axisymmetric or 2-D planar numerical models for repositories in salt. The accuracy limits of 2-D modeling were defined by comparing results from 3-dimensional (3-D) TRUMP modeling with results from both 2-D axisymmetric andmore » 2-D planar. Both TRUMP and ADINAT were employed as modeling tools. Two-dimensional results from the finite element code, ADINAT were compared with 2-D results from the finite difference code, TRUMP; they showed almost perfect correspondence in the far-field. This result adds substantially to confidence in future use of ADINAT and its companion stress code ADINA for thermal stress analysis. ADINAT was found to be somewhat sensitive to time step and mesh aspect ratio. 13 figures, 4 tables.« less

Crystal structure of (2-{[(8-aminona-phthalen-1-yl)imino]-meth-yl}-4,6-di-tert-butyl-phenolato-κ3N,N',O)bromido-nickel(II).

PubMed

O'Brien, Patrick; Zeller, Matthias; Lee, Wei-Tsung

2018-04-01

The title compound, [NiBr(C 25 H 29 N 2 O)], contains an Ni II atom with a slightly distorted square-planar coordination environment defined by one O and two N atoms from the 2-{[(8-aminona-phthalen-1-yl)imino]-meth-yl}-4,6-di- tert -butyl-phenolate ligand and a bromide anion. The Ni-O and Ni-N bond lengths are slightly longer than those observed in the phenyl backbone counterpart, which can be attributed to the larger steric hindrance of the naphthyl group in the structure of the title compound. The mol-ecule as a whole is substanti-ally distorted, with both the planar naphthalene-1,8-di-amine and imino-meth-yl-phenolate substitutents rotated against the NiN 2 OBr plane by 38.92 (7) and 37.22 (8)°, respectively, giving the mol-ecule a twisted appearance. N-H⋯Br hydrogen bonds and N-H⋯C(π) contacts connect the mol-ecules into dimers, and additional C-H⋯Br contacts, C-H⋯π inter-actions, and an offset stacking inter-action between naphthyl units inter-connect these dimers into a three-dimensional network.

Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

2016-05-01

In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm2, an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm2. Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification.

Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells.

PubMed

Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

2016-05-17

In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm(2), an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm(2). Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification.

Alignment of smectic mesogens over engineered surfaces

NASA Astrophysics Data System (ADS)

Chandran, Achu; Joshi, Tilak; Khanna, P. K.; Mehta, Dalip. S.; Haranath, D.; Biradar, Ashok M.

2017-07-01

The alignment of smectic C* liquid crystals (LCs) has been manipulated over and near different surfaces such as bare glass, indium tin oxide (ITO) coated glass, patterned glass, and near spacers. The LC sample cell is made of one ITO coated glass plate and other having striped ITO with a Mylar spacer maintaining a finite cell gap between them. Laser scribing is used to make striped ITO, while the scribed area results in the formation of the patterned glass surface. The geometry of the cell is such that overlapped ITO lie in the middle and spacers are placed in the two extreme corners of the cell. The alignment of LC is found to be homeotropic over the ITO coated glass, while it is planar near the spacer. Interestingly, a transition from homeotropic to planar is observed while moving away from the middle towards either corner of the cell. The origin of both types of alignment in the same cell has been explained by considering the difference in the surface energy of different surfaces. This work renders new advancement towards the manipulation of LC alignment using different surfaces and interfaces for advanced electro-optical and photonic devices based on LCs.

Self-adaptive method for high frequency multi-channel analysis of surface wave method

USDA-ARS?s Scientific Manuscript database

When the high frequency multi-channel analysis of surface waves (MASW) method is conducted to explore soil properties in the vadose zone, existing rules for selecting the near offset and spread lengths cannot satisfy the requirements of planar dominant Rayleigh waves for all frequencies of interest ...

Silicon Dioxide Planarization: Impacts on Optical Coatings for High Energy Laser

NASA Astrophysics Data System (ADS)

Day, Travis E.

The work of this thesis is devoted to examining the impact of silicon dioxide (silica or SiO2) planarization on the optical properties and laser damage resistance of thin-film coatings. SiO2 planarization is a process to smooth out fluence limiting nodular defects within multilayer coatings for high-energy laser applications. Mitigating these defects will improve the power handling abilities and improve the lifetime of laser coatings. Presented here is a combination of work with the aim of evaluating the optical and laser damage properties of SiO2 planarization within single layers, bilayers, and multilayers. As compared to control (non-planarized) samples, a 2-3x increase in the thin-film absorption, which decreases with post-process annealing, was discovered for SiO2 planarized samples. This suggests that planarization creates oxygen-related defects which can be annealed out and little impurity implantation. Investigations of laser damage resistance were carried out at lambda = 1030nm and pulse durations of tau = 220ps and 9ps. The laser damage of single and bilayer coatings is known to be dependent on the substrate-coating interface and this is further evidenced within this thesis. This is because the effects of planarization are masked by the extrinsic laser damage processes within the single and bilayers. Slight change (< 15%) in the laser induced damage threshold (LIDT) at 220ps and 9ps was observed for planarized single and bilayers. Depending on coating design, post-process annealing was shown to increase the LIDT by 10% to 75% at 220ps and 10% to 45% at 9ps. Although the fused silica substrate surface LIDT was shown to follow the √tau pulse scaling law for pulses above 10ps, the single and bilayer coatings do not follow this pulse scaling. The divergence from the √tau pulse scaling on the coatings suggests a variation in the laser damage initiation mechanisms between 220ps and 9ps. Multilayer high-reflecting (HR) mirrors with varying planarization design were also damage tested. A 6-7 J/cm2 LIDT, with 220ps, was observed for HR coatings with SiO2 planarization layers within high electric-field areas within the coating. However, SiO2 planarization at the substrate-coating interface, where the electric-field is minimal, and control (non-planarized) was shown to have a LIDT of 63 +/- 1.2 J/cm 2 and 21.5 +/- 0.5 J/cm2 for 220ps, respectively. At 9ps, the LIDT varied less than 90% difference between the various planarization designs. The substrate-coating planarization multilayer and control coating had an equal LIDT of 9.6 +/- .3 J/cm2 at 9ps.

Lead Acetate Based Hybrid Perovskite Through Hot Casting for Planar Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Shin, Gwang Su; Choi, Won-Gyu; Na, Sungjae; Gökdemir, Fatma Pinar; Moon, Taeho

2018-03-01

Flawless coverage of a perovskite layer is essential in order to achieve realistic high-performance planar heterojunction solar cells. We present that high-quality perovskite layers can be efficiently formed by a novel hot casting route combined with MAI (CH3NH3I) and non-halide lead acetate (PbAc2) precursors under ambient atmosphere. Casting temperature is controlled to produce various perovskite microstructures and the resulted crystalline layers are found to be comprised of closely packed islands with a smooth surface structure. Lead acetate employed perovskite solar cells are fabricated using PEDOT:PSS and PCBM charge transporting layers, in p- i- n type planar architecture. Especially, the outstanding open-circuit voltage demonstrates the high crystallinity and dense coverage of the produced perovskite layers by this facile route.

Theory of third-order spectroscopic methods to extract detailed molecular orientational dynamics for planar surfaces and other uniaxial systems

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

Nishida, Jun; Fayer, Michael D., E-mail: fayer@stanford.edu

Functionalized organic monolayers deposited on planar two-dimensional surfaces are important systems for studying ultrafast orientational motions and structures of interfacial molecules. Several studies have successfully observed the orientational relaxation of functionalized monolayers by fluorescence depolarization experiments and recently by polarization-resolved heterodyne detected vibrational transient grating (HDTG) experiments. In this article we provide a model-independent theory to extract orientational correlation functions unique to interfacial molecules and other uniaxial systems based on polarization-resolved resonant third-order spectroscopies, such as pump-probe spectroscopy, HDTG spectroscopy, and fluorescence depolarization experiment. It will be shown (in the small beam-crossing angle limit) that five measurements are necessary tomore » completely characterize the monolayer's motions: I{sub ∥}(t) and I{sub ⊥}(t) with the incident beams normal to the surface, I{sub ∥}(t) and I{sub ⊥}(t) with a non-zero incident angle, and a time averaged linear dichroism measurement. Once these measurements are performed, two orientational correlation functions corresponding to in-plane and out-of-plane motions are obtained. The procedure is applicable not only for monolayers on flat surfaces, but any samples with uniaxial symmetry such as uniaxial liquid crystals and aligned planar bilayers. The theory is valid regardless of the nature of the actual molecular motions on interface. We then apply the general results to wobbling-in-a-cone model, in which molecular motions are restricted to a limited range of angles. Within the context of the model, the cone angle, the tilt of the cone relative to the surface normal, and the orientational diffusion constant can be determined. The results are extended to describe analysis of experiments where the beams are not crossing in the small angle limit.« less

Algorithm for ion beam figuring of low-gradient mirrors.

PubMed

Jiao, Changjun; Li, Shengyi; Xie, Xuhui

2009-07-20

Ion beam figuring technology for low-gradient mirrors is discussed. Ion beam figuring is a noncontact machining technique in which a beam of high-energy ions is directed toward a target workpiece to remove material in a predetermined and controlled fashion. Owing to this noncontact mode of material removal, problems associated with tool wear and edge effects, which are common in conventional contact polishing processes, are avoided. Based on the Bayesian principle, an iterative dwell time algorithm for planar mirrors is deduced from the computer-controlled optical surfacing (CCOS) principle. With the properties of the removal function, the shaping process of low-gradient mirrors can be approximated by the linear model for planar mirrors. With these discussions, the error surface figuring technology for low-gradient mirrors with a linear path is set up. With the near-Gaussian property of the removal function, the figuring process with a spiral path can be described by the conventional linear CCOS principle, and a Bayesian-based iterative algorithm can be used to deconvolute the dwell time. Moreover, the selection criterion of the spiral parameter is given. Ion beam figuring technology with a spiral scan path based on these methods can be used to figure mirrors with non-axis-symmetrical errors. Experiments on SiC chemical vapor deposition planar and Zerodur paraboloid samples are made, and the final surface errors are all below 1/100 lambda.

Process for producing clad superconductive materials

DOEpatents

Cass, Richard B.; Ott, Kevin C.; Peterson, Dean E.

1992-01-01

A process for fabricating superconducting composite wire by the steps of placing a superconductive precursor admixture capable of undergoing a self propagating combustion in stoichiometric amounts sufficient to form a superconductive product within a metal tube, sealing one end of said tube, igniting said superconductive precursor admixture whereby said superconductive precursor admixture endburns along the length of the admixture, and cross-section reducing said tube at a rate substantially equal to the rate of burning of said superconductive precursor admixture and at a point substantially planar with the burnfront of the superconductive precursor mixture, whereby a clad superconductive product is formed in situ, the product characterized as superconductive without a subsequent sintering stage, is disclosed.

Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions

DOE PAGES

Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; ...

2016-12-07

The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedralmore » shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.« less

Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions.

PubMed

Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

2016-12-07

The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.

Structural characterization of bulk GaN crystals grown under high hydrostatic pressure

NASA Astrophysics Data System (ADS)

Liliental-Weber, Zuzanna; Kisielowski, C.; Ruvimov, S.; Chen, Y.; Washburn, J.; Grzegory, I.; Bockowski, M.; Jun, J.; Porowski, S.

1996-09-01

This paper describes TEM characterization of bulk GaN crystals grown at 1500-1800Kin the form of plates from a solution of atomic nitrogen in liquid gallium under high nitrogen pressure (up to 20 kbars). The x-ray rocking curves for these crystals were in the range of 20-30 arc-sec. The plate thickness along the c axis was about 100 times smaller than the nonpolar growth directions. A substantial difference in material quality was observed on the opposite sides of the plates normal to the c direction. On one side the surface was atomically flat, while on the other side the surface was rough, with pyramidal features up to 100 nm high. The polarity of the crystals was determined using convergent-beam electron diffraction. The results showed that, regarding the long bond between Ga and N along the c-axis, Ga atoms were found to be closer to the flat side of the crystal, while N atoms were found to be closer to the rough side. Near the rough side, within 1/10 to 1/4 of the plate thickness, there was a high density of planar defects (stacking faults and dislocation loops decorated by Ga/void precipitates). A model explaining the defect formation is proposed.

Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions

PubMed Central

Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

2016-01-01

The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape. PMID:27924857

Method for forming suspended micromechanical structures

DOEpatents

Fleming, James G.

2000-01-01

A micromachining method is disclosed for forming a suspended micromechanical structure from {111} crystalline silicon. The micromachining method is based on the use of anisotropic dry etching to define lateral features of the structure which are etched down into a {111}-silicon substrate to a first etch depth, thereby forming sidewalls of the structure. The sidewalls are then coated with a protection layer, and the substrate is dry etched to a second etch depth to define a spacing of the structure from the substrate. A selective anisotropic wet etchant (e.g. KOH, EDP, TMAH, NaOH or CsOH) is used to laterally undercut the structure between the first and second etch depths, thereby forming a substantially planar lower surface of the structure along a {111} crystal plane that is parallel to an upper surface of the structure. The lateral extent of undercutting by the wet etchant is controlled and effectively terminated by either timing the etching, by the location of angled {111}-silicon planes or by the locations of preformed etch-stops. This present method allows the formation of suspended micromechanical structures having large vertical dimensions and large masses while allowing for detailed lateral features which can be provided by dry etch definition. Additionally, the method of the present invention is compatible with the formation of electronic circuitry on the substrate.

Ultrathin hexagonal MgO nanoflakes coated medical textiles and their enhanced antibacterial activity

NASA Astrophysics Data System (ADS)

Veeran Ponnuvelu, Dinesh; Selvaraj, Aravind; Prema Suriyaraj, Shanmugam; Selvakumar, Rajendran; Pulithadathail, Biji

2016-10-01

A facile hydrothermal method for development of ultrathin MgO nanoplates from different precursors and their enhanced antibacterial activity after coating onto medical textiles is reported. Ultrathin MgO nanoplates having hexagonal structure were characterized using UV-visible spectroscopy, atomic force microscopy, field emission scanning electron microscopy, x-ray diffraction and high resolution transmission electron microscopy. The formation of MgO nanoplates was found to exhibit profound anionic effect leading to ultrathin, planar structures with exposed MgO [111] facets, which may be responsible for enhanced antimicrobial activity. Medical fabrics (bleached 100% cotton) were coated with MgO nanoplates using pad-dry-cure method. The antibacterial activity of these fabrics was tested against Bacillus subtilis and Escherichia coli. The MgO nanoplates coated onto the fabric were found to have good adherence properties owing to their two-dimensional structure and were durable even after repeated washings without substantial reduction in the antimicrobial activity. The enhanced antibacterial activity may be attributed to the presence of oxygen vacancies, surface oxygen anions and hydroxyl groups on the surface of MgO nanoplates. This cost-effective functional finish (anti-microbial) to cotton fabric using MgO nanoplates may be suitable for many prospective medical applications and can serve as an alternative to the costlier silver based antimicrobial textiles.

White emission from non-planar InGaN/GaN MQW LEDs grown on GaN template with truncated hexagonal pyramids.

PubMed

Lee, Ming-Lun; Yeh, Yu-Hsiang; Tu, Shang-Ju; Chen, P C; Lai, Wei-Chih; Sheu, Jinn-Kong

2015-04-06

Non-planar InGaN/GaN multiple quantum well (MQW) structures are grown on a GaN template with truncated hexagonal pyramids (THPs) featuring c-plane and r-plane surfaces. The THP array is formed by the regrowth of the GaN layer on a selective-area Si-implanted GaN template. Transmission electron microscopy shows that the InGaN/GaN epitaxial layers regrown on the THPs exhibit different growth rates and indium compositions of the InGaN layer between the c-plane and r-plane surfaces. Consequently, InGaN/GaN MQW light-emitting diodes grown on the GaN THP array emit multiple wavelengths approaching near white light.

Atomic-scale planarization of 4H-SiC (0001) by combination of thermal oxidation and abrasive polishing

NASA Astrophysics Data System (ADS)

Deng, Hui; Endo, Katsuyoshi; Yamamura, Kazuya

2013-09-01

Thermal oxidation (TO) and abrasive polishing were combined for atomic-scale planarization of 4H-SiC. It was found that the oxide/SiC interface was atomically flat regardless of the thickness of the oxide. The specimen prepared by TO was dipped in HF solution to remove the oxide. However, owing to the residual silicon oxycarbide (Si-C-O), the step/terrace structure of 4H-SiC could not be observed. Nanoindentation tests revealed that the hardness of Si-C-O was much lower than that of SiC. A thermally oxidized SiC surface was polished using CeO2 abrasives, which resulted in an atomically flat surface with a well-ordered two-bilayer step/terrace structure.

Lattice surgery on the Raussendorf lattice

NASA Astrophysics Data System (ADS)

Herr, Daniel; Paler, Alexandru; Devitt, Simon J.; Nori, Franco

2018-07-01

Lattice surgery is a method to perform quantum computation fault-tolerantly by using operations on boundary qubits between different patches of the planar code. This technique allows for universal planar code computation without eliminating the intrinsic two-dimensional nearest-neighbor properties of the surface code that eases physical hardware implementations. Lattice surgery approaches to algorithmic compilation and optimization have been demonstrated to be more resource efficient for resource-intensive components of a fault-tolerant algorithm, and consequently may be preferable over braid-based logic. Lattice surgery can be extended to the Raussendorf lattice, providing a measurement-based approach to the surface code. In this paper we describe how lattice surgery can be performed on the Raussendorf lattice and therefore give a viable alternative to computation using braiding in measurement-based implementations of topological codes.

Numerical simulations of mounding and submerging flows of shear-thinning jets impinging in a container

DOE PAGES

Roberts, Scott A.; Rao, Rekha R.

2011-10-01

Continuous jets of non-Newtonian fluids impinging on a fluid surface exhibit instabilities from jet buckling and coiling at low Reynolds numbers to delayed die swell, mounding, and air entrainment at higher Reynolds numbers. Filling containers with complex fluids is an important process for many industries, where the need for high throughput requires operating at high Reynolds numbers. In this regime, air entrainment can produce a visually unappealing product, causing a major quality control issue. Just prior to the onset of air entrainment, however, there exists an ideal filling regime which we term “planar filling,” as it is characterized by amore » relatively flat free surface that maintains its shape over time. In this paper, we create a steady-state, 2-D axisymmetric finite element model to study the transition from planar filling to the onset of air entrainment in a container filling process with generalized-Newtonian fluids. We use this model to explore the operating window for Newtonian and shear-thinning (or, more generally, deformation-rate-thinning) fluids, demonstrating that the flow behavior is characterized by a balance between inertial, viscous, and gravitational forces, as characterized by the Reynolds and Froude numbers. A scaling analysis suggests that the relevant parameters for calculating these dimensionless numbers are located where the jet impacts the liquid surface, and simulations show that the transition from planar filling to air entrainment often occurs when Re ~ O(10). Our study found that the bottom and side surfaces of the container drastically influence this transition to entrainment, stabilizing the flow.« less

Graph-based surface reconstruction from stereo pairs using image segmentation

NASA Astrophysics Data System (ADS)

Bleyer, Michael; Gelautz, Margrit

2005-01-01

This paper describes a novel stereo matching algorithm for epipolar rectified images. The method applies colour segmentation on the reference image. The use of segmentation makes the algorithm capable of handling large untextured regions, estimating precise depth boundaries and propagating disparity information to occluded regions, which are challenging tasks for conventional stereo methods. We model disparity inside a segment by a planar equation. Initial disparity segments are clustered to form a set of disparity layers, which are planar surfaces that are likely to occur in the scene. Assignments of segments to disparity layers are then derived by minimization of a global cost function via a robust optimization technique that employs graph cuts. The cost function is defined on the pixel level, as well as on the segment level. While the pixel level measures the data similarity based on the current disparity map and detects occlusions symmetrically in both views, the segment level propagates the segmentation information and incorporates a smoothness term. New planar models are then generated based on the disparity layers' spatial extents. Results obtained for benchmark and self-recorded image pairs indicate that the proposed method is able to compete with the best-performing state-of-the-art algorithms.

A hydrophilic polymer based microfluidic system with planar patch clamp electrode array for electrophysiological measurement from cells.

PubMed

Xu, Baojian; Ye, WeiWei; Zhang, Yu; Shi, JingYu; Chan, ChunYu; Yao, XiaoQiang; Yang, Mo

2014-03-15

This paper presents a microfluidic planar patch clamp system based on a hydrophilic polymer poly(ethylene glycol) diacrylate (PEGDA) for whole cell current recording. The whole chip is fabricated by UV-assisted molding method for both microfluidic channel structure and planar electrode partition. This hydrophilic patch clamp chip has demonstrated a relatively high gigaseal success rate of 44% without surface modification compared with PDMS based patch clamp devices. This chip also shows a capability of rapid intracellular and extracellular solution exchange with high stability of gigaseals. The capillary flow kinetic experiments demonstrate that the flow rates of PEGDA microfluidic channels are around two orders of magnitude greater than those for PDMS-glass channels with the same channel dimensions. This hydrophilic polymer based patch clamp chips have significant advantages over current PDMS elastomer based systems such as no need for surface modification, much higher success rate of cell gigaseals and rapid solution exchange with stable cell gigaseals. Our results indicate the potential of these devices to serve as useful tools for pharmaceutical screening and biosensing tasks. © 2013 Elsevier B.V. All rights reserved.

Experimental Investigation of the Electrothermal Instability on Planar Foil Ablation Experiments

NASA Astrophysics Data System (ADS)

Steiner, Adam; Patel, Sonal; Yager-Elorriaga, David; Jordan, Nicholas; Gilgenbach, Ronald; Lau, Y. Y.

2014-10-01

The electrothermal instability (ETI) is an important early-time physical effect on pulsed power foil ablation experiments due to its ability to seed the destructive magneto-Rayleigh-Taylor (MRT) instability. ETI occurs whenever electrical resistivity has temperature dependence; when resistivity increases with temperature, as with solid metal liners or foils, ETI forms striation structures perpendicular to current flow. These striations provide an initial perturbation for the MRT instability, which is the dominant late-time instability in planar foil ablations. The MAIZE linear transformer driver was used to drive current pulses of approximately 600 kA into 400 nm-thick aluminum foils in order to study ETI in planar geometry. Shadowgraph images of the aluminum plasmas were taken for multiple shots at various times within approximately 50 ns of current start. Fourier analysis extracted the approximate wavelengths of the instability structures on the plasma-vacuum interface. Surface metrology of pre-shot foils was performed to provide a comparison between surface roughness features and resulting plasma structure. This work was supported by US DoE. S.G. Patel and A.M. Steiner supported by NPSC funded by Sandia. D.A. Yager supported by NSF fellowship Grant # DGE 1256260.

Ultra-wideband filtering of spoof surface plasmon polaritons using deep subwavelength planar structures

PubMed Central

Hu, Ming Zhe; Zhang, Hao Chi; Yin, Jia Yuan; Ding, Zhao; Liu, Jun Feng; Tang, Wen Xuan; Cui, Tie Jun

2016-01-01

Novel ultra-wideband filtering of spoof surface plasmon polaritons (SPPs) is proposed in the microwave frequency using deep subwavelength planar structures printed on thin and flexible dielectric substrate. The proposed planar SPPs waveguide is composed of two mirror-oriented metallic corrugated strips, which are further decorated with parallel-arranged slots in the main corrugated strips. This compound structure provides deep subwavelength field confinement as well as flexible parameters when employed as a plasmonic waveguide, which is potential to construct miniaturization. Using momentum and impedance matching technology, we achieve a smooth conversion between the proposed SPPs waveguide and the conventional transmission line. To verify the validity of the design, we fabricate a spoof SPPs filter, and the measured results illustrate excellent performance, in which the reflection coefficient is less than −10 dB within the −3 dB passband from 1.21 GHz to 7.21 GHz with the smallest insertion loss of 1.23 dB at 2.21 GHz, having very good agreements with numerical simulations. The ultra-wideband filter with low insertion loss and high transmission efficiency possesses great potential in modern communication systems. PMID:27883028

Ultra-wideband filtering of spoof surface plasmon polaritons using deep subwavelength planar structures.

PubMed

Hu, Ming Zhe; Zhang, Hao Chi; Yin, Jia Yuan; Ding, Zhao; Liu, Jun Feng; Tang, Wen Xuan; Cui, Tie Jun

2016-11-24

Novel ultra-wideband filtering of spoof surface plasmon polaritons (SPPs) is proposed in the microwave frequency using deep subwavelength planar structures printed on thin and flexible dielectric substrate. The proposed planar SPPs waveguide is composed of two mirror-oriented metallic corrugated strips, which are further decorated with parallel-arranged slots in the main corrugated strips. This compound structure provides deep subwavelength field confinement as well as flexible parameters when employed as a plasmonic waveguide, which is potential to construct miniaturization. Using momentum and impedance matching technology, we achieve a smooth conversion between the proposed SPPs waveguide and the conventional transmission line. To verify the validity of the design, we fabricate a spoof SPPs filter, and the measured results illustrate excellent performance, in which the reflection coefficient is less than -10 dB within the -3 dB passband from 1.21 GHz to 7.21 GHz with the smallest insertion loss of 1.23 dB at 2.21 GHz, having very good agreements with numerical simulations. The ultra-wideband filter with low insertion loss and high transmission efficiency possesses great potential in modern communication systems.

A novel form of epithelial wound healing of the embryonic epidermis.

PubMed

Armstrong, Margaret T; Turlo, Kirsten; Elges, Chris J; Dayton, Sarah M; Lee, Janet; Armstrong, Peter B

2006-08-01

The embryonic epidermis of amniotes is a two-cell layer sheet with a periderm positioned superficial to the basal cell layer which, itself, attaches apically to the basal surface of the periderm and basally to the basal lamina. The presence of the periderm is essential to maintain the basal layer as a two-dimensional monolayer. Wounds to the epidermis that remove selectively just the periderm are healed by a stacking of the basal layer cells that constitute the wound bed. Basal cell stacking involves the desertion of the basal lamina by many of the cells so as to increase their contact area with other basal layer cells. This suggests that a preferential adhesion to the planar basal lamina is not important for the monolayered organization of the basal layer but, instead, association with inner surface of the planar periderm is the principal process that maintains the basal layer as a monolayer. The conversion of the basal layer from monolayer to multilayer during wound healing diminishes its planar area, resulting in movement of the wound borders toward the center of the wound. This is a novel scenario for wound healing.

The influence of low-energy helium plasma on bubble formation in micro-engineered tungsten

NASA Astrophysics Data System (ADS)

Gao, Edward; Nadvornick, Warren; Doerner, Russ; Ghoniem, Nasr M.

2018-04-01

Four different types of micro-engineered tungsten surfaces were exposed to low energy helium plasma, with a planar surface as control. These samples include two surfaces covered with uniform W-coated rhenium micro-pillars; one with cylindrical pillars 1 μm in diameter and 25 μm in height, and one with dendritic conical pillars 4-10 μm in diameter and 20 μm in height. Additionally, two samples with reticulated open-cell foam geometry, one at 45 pores per inch (PPI), and the other at 80 PPI were fabricated with Chemical Vapor Deposition (CVD). The samples were exposed to helium plasma at 30-100 eV ion energy, 823-1123 K temperature, and 5 × 1025 - 2 × 1026 m-2 ion fluence. It is shown that the formation of nanometer-scale tendrils (fuzz) on micro-engineered W surfaces is greatly reduced as compared to planar surfaces. This is attributed to more significant ion backscattering and the increased effective surface area that intercept incident ions in micro-engineered W. A 20% decrease in the average ion incident angle on pillar type surfaces leads to ∼30% decrease in bubble size, down to 30 nm in diameter. W fuzz was found to be absent from pillar sides due to high ion backscattering rates from pillar sides. In foam samples, 28% higher PPI is observed to have 24.7%-36.7% taller fuzz, and 17.0%-25.0% larger subsurface bubbles. These are found to be an order of magnitude smaller than those found in planar surfaces of similar environment. The helium bubble density was found to increase with ion energy in pillars, roughly from 8.2% to 48.4%, and to increase with increasing PPI, from 36.4% to 116.2%, and with bubble concentrations up to 9.1 × 1021 m-3. Geometric shadowing effects in or near surface ligaments are observed in all foam samples, with near absence of helium bubbles or fuzz in deeper layers of the foam.

The effect of grid transparency and finite collector size on determining ion temperature and density by the retarding potential analyzer

NASA Technical Reports Server (NTRS)

Troy, B. E., Jr.; Maier, E. J.

1973-01-01

The analysis of ion data from retarding potential analyzers (RPA's) is generally done under the planar approximation, which assumes that the grid transparency is constant with angle of incidence and that all ions reaching the plane of the collectors are collected. These approximations are not valid for situations in which the ion thermal velocity is comparable to the vehicle velocity, causing ions to enter the RPA with high average transverse velocity. To investigate these effects, the current-voltage curves for H+ at 4000 K were calculated, taking into account the finite collector size and the variation of grid transparency with angle. These curves are then analyzed under the planar approximation. The results show that only small errors in temperature and density are introduced for an RPA with typical dimensions; and that even when the density error is substantial for non-typical dimensions, the temperature error remains minimal.

0.87-micron CSP diode lasers for spaceborne communications. [channeled-substrate-planar

NASA Technical Reports Server (NTRS)

Carlin, D. B.; Pultz, G. N.; Goldstein, B.

1987-01-01

Index-guided channeled-substrate-planar (CSP) AlGaAs diode lasers are being developed for reliable, high-power operation for use as sources in spaceborne optical communications systems. Although most work on this AlGaAs structure has been aimed at optimizing performance at output wavelengths less than 8400 A, emission in the 8700 A regime is also of interest. In particular, such wavelengths are required for use in the direct detection laser transceiver to be incorporated into NASA's advanced communications technology satellite, in order to avoid absorption of the light by the atmosphere when communicating with ground-based terminals. Lowest order spatial mode and substantially single longitudinal mode output has been observed in 0.87-micron CSP devices in excess of 50 mW cw and 100 mW 50 percent duty-cycle, with rms phase-front aberrations measured to be about lambda/40.

Gas turbine bucket with impingement cooled platform

DOEpatents

Jones, Raphael Durand

2002-01-01

In a turbine bucket having an airfoil portion and a root portion, with a substantially planar platform at an interface between the airfoil portion and root portion, a platform cooling arrangement including at least one bore in the root portion and at least one impingement cooling tube seated in the bore, the tube extending beyond the bore with an outlet in close proximity to a targeted area on an underside of the platform.

A fast passive and planar liquid sample micromixer.

PubMed

Melin, Jessica; Gimenéz, Guillem; Roxhed, Niclas; van der Wijngaart, Wouter; Stemme, Göran

2004-06-01

A novel microdevice for passively mixing liquid samples based on surface tension and a geometrical mixing chamber is presented. Due to the laminar flow regime on the microscale, mixing becomes difficult if not impossible. We present a micromixer where a constantly changing time dependent flow pattern inside a two sample liquid plug is created as the plug simply passes through the planar mixer chamber. The device requires no actuation during mixing and is fabricated using a single etch process. The effective mixing of two coloured liquid samples is demonstrated.

Theory of multiple quantum dot formation in strained-layer heteroepitaxy

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

Du, Lin; Maroudas, Dimitrios, E-mail: maroudas@ecs.umass.edu

2016-07-11

We develop a theory for the experimentally observed formation of multiple quantum dots (QDs) in strained-layer heteroepitaxy based on surface morphological stability analysis of a coherently strained epitaxial thin film on a crystalline substrate. Using a fully nonlinear model of surface morphological evolution that accounts for a wetting potential contribution to the epitaxial film's free energy as well as surface diffusional anisotropy, we demonstrate the formation of multiple QD patterns in self-consistent dynamical simulations of the evolution of the epitaxial film surface perturbed from its planar state. The simulation predictions are supported by weakly nonlinear analysis of the epitaxial filmmore » surface morphological stability. We find that, in addition to the Stranski-Krastanow instability, long-wavelength perturbations from the planar film surface morphology can trigger a nonlinear instability, resulting in the splitting of a single QD into multiple QDs of smaller sizes, and predict the critical wavelength of the film surface perturbation for the onset of the nonlinear tip-splitting instability. The theory provides a fundamental interpretation for the observations of “QD pairs” or “double QDs” and other multiple QDs reported in experimental studies of epitaxial growth of semiconductor strained layers and sets the stage for precise engineering of tunable-size nanoscale surface features in strained-layer heteroepitaxy by exploiting film surface nonlinear, pattern forming phenomena.« less

Bayesian techniques for surface fuel loading estimation

Treesearch

Kathy Gray; Robert Keane; Ryan Karpisz; Alyssa Pedersen; Rick Brown; Taylor Russell

2016-01-01

A study by Keane and Gray (2013) compared three sampling techniques for estimating surface fine woody fuels. Known amounts of fine woody fuel were distributed on a parking lot, and researchers estimated the loadings using different sampling techniques. An important result was that precise estimates of biomass required intensive sampling for both the planar intercept...

Determination of bulk diffusion lengths for angle-lapped semiconductor material via the scanning electron microscope: A theoretical analysis

NASA Technical Reports Server (NTRS)

Vonroos, O.

1978-01-01

A standard procedure for the determination of the minority carrier diffusion length by means of a scanning electron microscope (SEM) consists in scanning across an angle-lapped surface of a P-N junction and measuring the resultant short circuit current I sub sc as a function of beam position. A detailed analysis of the I sub sc originating from this configuration is presented. It is found that, for a point source excitation, the I sub sc depends very simply on x, the variable distance between the surface and the junction edge. The expression for the I sub sc of a planar junction device is well known. If d, the constant distance between the plane of the surface of the semiconductor and the junction edge in the expression for the I of a planar junction is merely replaced by x, the variable distance of the corresponding angle-lapped junction, an expression results which is correct to within a small fraction of a percent as long as the angle between the surfaces, 2 theta sub 1, is smaller than 10 deg.

Shape analysis of corpus callosum in autism subtype using planar conformal mapping

NASA Astrophysics Data System (ADS)

He, Qing; Duan, Ye; Yin, Xiaotian; Gu, Xianfeng; Karsch, Kevin; Miles, Judith

2009-02-01

A number of studies have documented that autism has a neurobiological basis, but the anatomical extent of these neurobiological abnormalities is largely unknown. In this study, we aimed at analyzing highly localized shape abnormalities of the corpus callosum in a homogeneous group of autism children. Thirty patients with essential autism and twenty-four controls participated in this study. 2D contours of the corpus callosum were extracted from MR images by a semiautomatic segmentation method, and the 3D model was constructed by stacking the contours. The resulting 3D model had two openings at the ends, thus a new conformal parameterization for high genus surfaces was applied in our shape analysis work, which mapped each surface onto a planar domain. Surface matching among different individual meshes was achieved by re-triangulating each mesh according to a template surface. Statistical shape analysis was used to compare the 3D shapes point by point between patients with autism and their controls. The results revealed significant abnormalities in the anterior most and anterior body in essential autism group.

Observer success rates for identification of 3D surface reconstructed facial images and implications for patient privacy and security

NASA Astrophysics Data System (ADS)

Chen, Joseph J.; Siddiqui, Khan M.; Fort, Leslie; Moffitt, Ryan; Juluru, Krishna; Kim, Woojin; Safdar, Nabile; Siegel, Eliot L.

2007-03-01

3D and multi-planar reconstruction of CT images have become indispensable in the routine practice of diagnostic imaging. These tools cannot only enhance our ability to diagnose diseases, but can also assist in therapeutic planning as well. The technology utilized to create these can also render surface reconstructions, which may have the undesired potential of providing sufficient detail to allow recognition of facial features and consequently patient identity, leading to violation of patient privacy rights as described in the HIPAA (Health Insurance Portability and Accountability Act) legislation. The purpose of this study is to evaluate whether 3D reconstructed images of a patient's facial features can indeed be used to reliably or confidently identify that specific patient. Surface reconstructed images of the study participants were created used as candidates for matching with digital photographs of participants. Data analysis was performed to determine the ability of observers to successfully match 3D surface reconstructed images of the face with facial photographs. The amount of time required to perform the match was recorded as well. We also plan to investigate the ability of digital masks or physical drapes to conceal patient identity. The recently expressed concerns over the inability to truly "anonymize" CT (and MRI) studies of the head/face/brain are yet to be tested in a prospective study. We believe that it is important to establish whether these reconstructed images are a "threat" to patient privacy/security and if so, whether minimal interventions from a clinical perspective can substantially reduce this possibility.

A DNS study of the physical mechanisms associated with density ratio influence on turbulent burning velocity in premixed flames

NASA Astrophysics Data System (ADS)

Lipatnikov, Andrei N.; Chomiak, Jerzy; Sabelnikov, Vladimir A.; Nishiki, Shinnosuke; Hasegawa, Tatsuya

2018-01-01

Data obtained in 3D direct numerical simulations of statistically planar, 1D weakly turbulent flames characterised by different density ratios σ are analysed to study the influence of thermal expansion on flame surface area and burning rate. Results show that, on the one hand, the pressure gradient induced within a flame brush owing to heat release in flamelets significantly accelerates the unburned gas that deeply intrudes into the combustion products in the form of an unburned mixture finger, thus causing large-scale oscillations of the burning rate and flame brush thickness. Under the conditions of the present simulations, the contribution of this mechanism to the creation of the flame surface area is substantial and is increased by σ, thus implying an increase in the burning rate by σ. On the other hand, the total flame surface areas simulated at σ = 7.53 and 2.5 are approximately equal. The apparent inconsistency between these results implies the existence of another thermal expansion effect that reduces the influence of σ on the flame surface area and burning rate. Investigation of the issue shows that the flow acceleration by the combustion-induced pressure gradient not only creates the flame surface area by pushing the finger tip into the products, but also mitigates wrinkling of the flame surface (the side surface of the finger) by turbulent eddies. The latter effect is attributed to the high-speed (at σ = 7.53) axial flow of the unburned gas, which is induced by the axial pressure gradient within the flame brush (and the finger). This axial flow acceleration reduces the residence time of a turbulent eddy in an unburned zone of the flame brush (e.g. within the finger). Therefore, the capability of the eddy for wrinkling the flamelet surface (e.g. the side finger surface) is weakened owing to a shorter residence time.

Vascular stents with submicrometer-scale surface patterning realized via titanium deep reactive ion etching

NASA Astrophysics Data System (ADS)

Gott, Shannon C.; Jabola, Benjamin A.; Rao, Masaru P.

2015-08-01

Herein, we report progress towards realization of vascular stents that will eventually provide opportunity for evaluating cellular response to rationally-designed, submicrometer-scale surface patterning in physiologically-relevant contexts, i.e. those that provide exposure to the complex multicellular milieu, flow-induced shear, and tissue-device interactions present in vivo. Specifically, using our novel titanium deep reactive ion etching technique (Ti DRIE), we discuss recent advances that have enabled: (a) fabrication of precisely-defined, grating-based surface patterns on planar Ti foils with minimum feature sizes as small as 0.15 μm (b) creation of cylindrical stents from micromachined planar Ti foils; and (c) integration of these processes to produce the first submicrometer-scale surface-patterned Ti stents that are compatible with conventional balloon catheter deployment techniques. We also discuss results from elastoplastic finite element simulations and preliminary mechanical testing of these devices to assess their mechanical performance. These efforts represent key steps towards our long-term goal of developing a new paradigm in stenting, where rationally-designed surface patterning provides a physical means for facilitating healing, and thus, improving outcomes in vascular intervention applications.

Method for Molding Planar Billet of Thermally Insulative Material Into Predetermined Non-Planar Shape

NASA Technical Reports Server (NTRS)

Kolodziej, Paul (Inventor); Carroll, Joe A. (Inventor); Smith, Dane (Inventor)

1998-01-01

A method and apparatus is discussed for molding thermal protection system (TPS) tiles for spacecraft. The apparatus and method include a bottom mold member defining a mold surface shaped like a surface of the spacecraft, e.g., the nose cap of wing leading edge, sought to be thermally protected. A flat billet of TPS material is positioned over the periphery of the mold surface, and a hollow weight element that has a periphery configured like the periphery of the mold surface is positioned on the billet. The billet is then heated in accordance with a predetermined heating regime, and during the heating process the weight of the weight element causes the billet to deform to assume the shape of the mold surface. If desired, a TUFI coating is impregnated into the billet prior to heating, and the coating is sintered to the billet during heating. After heating, a composite matrix material, e.g., a graphite or fiberglass cloth which is impregnated with epoxy or polimide, is bonded to the now-shaped tile to support the tile. Silicone can then be impregnated into the now-formed tile to provide flexibility of the tile.

Wrinkled, wavelength-tunable graphene-based surface topographies for directing cell alignment and morphology

PubMed Central

Wang, Zhongying; Tonderys, Daniel; Leggett, Susan E.; Williams, Evelyn Kendall; Kiani, Mehrdad T.; Steinberg, Ruben Spitz; Qiu, Yang; Wong, Ian Y.; Hurt, Robert H.

2015-01-01

Textured surfaces with periodic topographical features and long-range order are highly attractive for directing cell-material interactions. They mimic physiological environments more accurately than planar surfaces and can fundamentally alter cell alignment, shape, gene expression, and cellular assembly into superstructures or microtissues. Here we demonstrate for the first time that wrinkled graphene-based surfaces are suitable as textured cell attachment substrates, and that engineered wrinkling can dramatically alter cell alignment and morphology. The wrinkled surfaces are fabricated by graphene oxide wet deposition onto pre-stretched elastomers followed by relaxation and mild thermal treatment to stabilize the films in cell culture medium. Multilayer graphene oxide films form periodic, delaminated buckle textures whose wavelengths and amplitudes can be systematically tuned by variation in the wet deposition process. Human and murine fibroblasts attach to these textured films and remain viable, while developing pronounced alignment and elongation relative to those on planar graphene controls. Compared to lithographic patterning of nanogratings, this method has advantages in the simplicity and scalability of fabrication, as well as the opportunity to couple the use of topographic cues with the unique conductive, adsorptive, or barrier properties of graphene materials for functional biomedical devices. PMID:25848137

Effect of polymer residues on the electrical properties of large-area graphene–hexagonal boron nitride planar heterostructures

DOE PAGES

Voyloy, Dimitry; Lassiter, Matthew G.; Sokolov, Alexei P.; ...

2017-06-19

Polymer residue plays an important role in the performance of 2D heterostructured materials. Herein, we study the effect of polymer residual impurities on the electrical properties of graphene–boron nitride planar heterostructures. Large-area graphene (Gr) and hexagonal boron nitride (h-BN) monolayers were synthesized using chemical vapor deposition techniques. Atomic van-der-Waals heterostructure layers based on varied configurations of Gr and h-BN layers were assembled. The average interlayer resistance of the heterojunctions over a 1 cm 2 area for several planar heterostructure configurations was assessed by impedance spectroscopy and modeled by equivalent electrical circuits. As a result, conductive AFM measurements showed that themore » presence of polymer residues on the surface of the Gr and h-BN monolayers resulted in significant resistance deviations over nanoscale regions.« less

Effect of polymer residues on the electrical properties of large-area graphene–hexagonal boron nitride planar heterostructures

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

Voyloy, Dimitry; Lassiter, Matthew G.; Sokolov, Alexei P.

Polymer residue plays an important role in the performance of 2D heterostructured materials. Herein, we study the effect of polymer residual impurities on the electrical properties of graphene–boron nitride planar heterostructures. Large-area graphene (Gr) and hexagonal boron nitride (h-BN) monolayers were synthesized using chemical vapor deposition techniques. Atomic van-der-Waals heterostructure layers based on varied configurations of Gr and h-BN layers were assembled. The average interlayer resistance of the heterojunctions over a 1 cm 2 area for several planar heterostructure configurations was assessed by impedance spectroscopy and modeled by equivalent electrical circuits. As a result, conductive AFM measurements showed that themore » presence of polymer residues on the surface of the Gr and h-BN monolayers resulted in significant resistance deviations over nanoscale regions.« less

Fabrication of planar waveguide in KNSBN crystal by swift heavy ion beam irradiation

NASA Astrophysics Data System (ADS)

Guan, Jing; Wang, Lei; Qin, Xifeng

2013-11-01

We report on the fabrication of the planar waveguides in the KNSBN crystal by using 17 MeV C5+ ions at a fluence of 2 × 1014 ions/cm2. After implantation, near surface regions of the crystal, there has a positive extraordinary refractive index (ne) change and the light inside the waveguides can propagate in a non-leaky manner. The two-dimensional modal profiles of the planar waveguides, measured by using the end-coupling arrangement, are in good agreement with the reconstructed modal distributions. The propagation loss for C5+ irradiated waveguide is ∼0.8 dB/cm at 633 nm and ∼0.72 dB/cm at 1064 nm. The waveguide gives good confinement of waveguide modes, which exhibits acceptable guiding qualities for potential applications in integrated optics.

The Microstructural Evolution of Fatigue Cracks in FCC Metals

NASA Astrophysics Data System (ADS)

Gross, David William

The microstructural evolution during fatigue crack propagation was investigated in a variety of planar and wavy slip FCC metals. The planar materials included Haynes 230, Nitronic 40, and 316 stainless steel, and the wavy materials included pure nickel and pure copper. Three different sets of experiments were performed to fully characterize the microstructural evolution. The first, performed on Haynes 230, mapped the strain field ahead a crack tip using digital image correlation and electron backscatter diffraction techniques. Focused ion beam (FIB) lift-out techniques were then utilized to extract transmission electron microscopy (TEM) samples at specific distances from the crack tip. TEM investigations compared the measured strain to the microstructure. Overall, the strain measured via DIC and EBSD was only weakly correlated to the density of planar slip bands in the microstructure. The second set of experiments concerned the dislocation structure around crack tips. This set of experiments was performed on all the materials. The microstructure at arrested fatigue cracks on the free surface was compared to the microstructure found beneath striations on the fracture surfaces by utilizing FIB micromachining to create site-specific TEM samples. The evolved microstructure depended on the slip type. Strong agreement was found between the crack tip microstructure at the free surface and the fracture surface. In the planar materials, the microstructure in the plastic zone consisted of bands of dislocations or deformation twins, before transitioning to a refined sub-grain microstructure near the crack flank. The sub-grain structure extended 300-500 nm away from the crack flank in all the planar slip materials studied. In contrast, the bulk structure in the wavy slip material consisted of dislocation cells and did not transition to a different microstructure as the crack tip was approached. The strain in wavy slip was highest near the crack tip, as the misorientations between the dislocation cells increased and the cell size decreased as the crack flank was approached. The final set of experiments involved reloading the arrested crack tips in monotonic tension. This was performed on both the Haynes 230 and 316 stainless steel. This technique exposed the fracture surface and location of the arrested crack tip away from the free surface, allowing for a sample to be extracted via FIB micromachining and TEM evaluation of the microstructure. This permitted the crack tip microstructure to be investigated without exposing the microstructure to crack closure or free surface effects. These experiments confirmed what was inferred from the earlier experiments, namely that the banded structure was a product of the crack tip plastic zone and the refined structure was a product of the strain associated with crack advance. Overall the microstructural complexity presented in this work was much higher than would be predicted by current models of fatigue crack propagation. It is recommended that future models attempt to simulate interactions between the dislocations emitted during fatigue crack growth and the pre-existing microstructure to more accurately simulate the processes occurring at the crack tip during crack growth.

Recent modelling advances for ultrasonic TOFD inspections

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

Darmon, Michel; Ferrand, Adrien; Dorval, Vincent

The ultrasonic TOFD (Time of Flight Diffraction) Technique is commonly used to detect and characterize disoriented cracks using their edge diffraction echoes. An overview of the models integrated in the CIVA software platform and devoted to TOFD simulation is presented. CIVA allows to predict diffraction echoes from complex 3D flaws using a PTD (Physical Theory of Diffraction) based model. Other dedicated developments have been added to simulate lateral waves in 3D on planar entry surfaces and in 2D on irregular surfaces by a ray approach. Calibration echoes from Side Drilled Holes (SDHs), specimen echoes and shadowing effects from flaws canmore » also been modelled. Some examples of theoretical validation of the models are presented. In addition, experimental validations have been performed both on planar blocks containing calibration holes and various notches and also on a specimen with an irregular entry surface and allow to draw conclusions on the validity of all the developed models.« less

Three dimensional, multi-chip module

DOEpatents

Bernhardt, A.F.; Petersen, R.W.

1993-08-31

A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow dummy chips'' are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned on the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.

Three dimensional, multi-chip module

DOEpatents

Bernhardt, Anthony F.; Petersen, Robert W.

1993-01-01

A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow "dummy chips" are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned o the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.

Ultracompact Pseudowedge Plasmonic Lasers and Laser Arrays.

PubMed

Chou, Yu-Hsun; Hong, Kuo-Bin; Chang, Chun-Tse; Chang, Tsu-Chi; Huang, Zhen-Ting; Cheng, Pi-Ju; Yang, Jhen-Hong; Lin, Meng-Hsien; Lin, Tzy-Rong; Chen, Kuo-Ping; Gwo, Shangjr; Lu, Tien-Chang

2018-02-14

Concentrating light at the deep subwavelength scale by utilizing plasmonic effects has been reported in various optoelectronic devices with intriguing phenomena and functionality. Plasmonic waveguides with a planar structure exhibit a two-dimensional degree of freedom for the surface plasmon; the degree of freedom can be further reduced by utilizing metallic nanostructures or nanoparticles for surface plasmon resonance. Reduction leads to different lightwave confinement capabilities, which can be utilized to construct plasmonic nanolaser cavities. However, most theoretical and experimental research efforts have focused on planar surface plasmon polariton (SPP) nanolasers. In this study, we combined nanometallic structures intersecting with ZnO nanowires and realized the first laser emission based on pseudowedge SPP waveguides. Relative to current plasmonic nanolasers, the pseudowedge plasmonic lasers reported in our study exhibit extremely small mode volumes, high group indices, high spontaneous emission factors, and high Purell factors beneficial for the strong interaction between light and matter. Furthermore, we demonstrated that compact plasmonic laser arrays can be constructed, which could benefit integrated plasmonic circuits.

Calculation of Latitude and Longitude for Points on Perimeter of a Circle on a Sphere

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

Morris, Heidi E.

2015-08-14

This document describes the calculation of the Earth-Centered Earth Fixed (ECEF) coordinates for points lying on the perimeter of a circle. Here, the perimeter of the circle lies on the surface of the sphere and the center of the planar circle is below the surface. These coordinates are converted to latitude and longitude for mapping fields on the surface of the earth.

Angle-Dependent Atomic Force Microscopy Single-Chain Pulling of Adsorbed Macromolecules from Planar Surfaces Unveils the Signature of an Adsorption-Desorption Transition.

PubMed

Grebíková, Lucie; Whittington, Stuart G; Vancso, Julius G

2018-05-23

The adsorption-desorption behavior of polymer chains is at the heart of macromolecular surface science and technology. With the current developments in atomic force microscopy (AFM), it has now become possible to address the desorption problem from the perspective of a single macromolecule. Here, we report on desorption of single polymer chains on planar surfaces by AFM-based single molecule force spectroscopy (SMFS) as a function of the pulling angle with respect to the surface-normal direction. SMFS experiments were performed in water with various substrates using different polymers covalently attached to the AFM probe tip. End-grafting at the AFM tip was achieved by surface-initiated polymerization using initiator functionalized tips. We found that the desorption force increases with a decreasing pulling angle, i.e., an enhanced adhesion of the polymer chain was observed. The magnitude of the desorption force shows a weak angular dependence at pulling angles close to the surface normal. A significant increase of the force is observed at shallower pulling from a certain pulling angle. This behavior carries the signature of an adsorption-desorption transition. The angular dependence of the normalized desorption force exhibits a universal behavior. We compared and interpreted our results using theoretical predictions for single-chain adsorption-desorption transitions.

Angle-Dependent Atomic Force Microscopy Single-Chain Pulling of Adsorbed Macromolecules from Planar Surfaces Unveils the Signature of an Adsorption–Desorption Transition

PubMed Central

2018-01-01

The adsorption–desorption behavior of polymer chains is at the heart of macromolecular surface science and technology. With the current developments in atomic force microscopy (AFM), it has now become possible to address the desorption problem from the perspective of a single macromolecule. Here, we report on desorption of single polymer chains on planar surfaces by AFM-based single molecule force spectroscopy (SMFS) as a function of the pulling angle with respect to the surface-normal direction. SMFS experiments were performed in water with various substrates using different polymers covalently attached to the AFM probe tip. End-grafting at the AFM tip was achieved by surface-initiated polymerization using initiator functionalized tips. We found that the desorption force increases with a decreasing pulling angle, i.e., an enhanced adhesion of the polymer chain was observed. The magnitude of the desorption force shows a weak angular dependence at pulling angles close to the surface normal. A significant increase of the force is observed at shallower pulling from a certain pulling angle. This behavior carries the signature of an adsorption–desorption transition. The angular dependence of the normalized desorption force exhibits a universal behavior. We compared and interpreted our results using theoretical predictions for single-chain adsorption–desorption transitions. PMID:29712430

Retrograde resonance in the planar three-body problem

NASA Astrophysics Data System (ADS)

Morais, M. H. M.; Namouni, F.

2013-12-01

We continue the investigation of the dynamics of retrograde resonances initiated in Morais and Giuppone (Mon Notices R Astron Soc 424:52-64, doi:10.1111/j.1365-2966.2012.21151.x, 2012). After deriving a procedure to deduce the retrograde resonance terms from the standard expansion of the three-dimensional disturbing function, we concentrate on the planar problem and construct surfaces of section that explore phase-space in the vicinity of the main retrograde resonances (2/1, 1/1 and 1/2). In the case of the 1/1 resonance for which the standard expansion is not adequate to describe the dynamics, we develop a semi-analytic model based on numerical averaging of the unexpanded disturbing function, and show that the predicted libration modes are in agreement with the behavior seen in the surfaces of section.

Hydrodynamic growth and decay of planar shock waves

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

Piriz, A. R., E-mail: roberto.piriz@uclm.es; Sun, Y. B.; Tahir, N. A.

2016-03-15

A model for the hydrodynamic attenuation (growth and decay) of planar shocks is presented. The model is based on the approximate integration of the fluid conservation equations, and it does not require the heuristic assumptions used in some previous works. A key issue of the model is that the boundary condition on the piston surface is given by the retarded pressure, which takes into account the transit time of the sound waves between the piston and any position at the bulk of the shocked fluid. The model yields the shock pressure evolution for any given pressure pulse on the piston,more » as well as the evolution of the trajectories, velocities, and accelerations on the shock and piston surfaces. An asymptotic analytical solution is also found for the decay of the shock wave.« less

Automated generation of influence functions for planar crack problems

NASA Technical Reports Server (NTRS)

Sire, Robert A.; Harris, David O.; Eason, Ernest D.

1989-01-01

A numerical procedure for the generation of influence functions for Mode I planar problems is described. The resulting influence functions are in a form for convenient evaluation of stress-intensity factors for complex stress distributions. Crack surface displacements are obtained by a least-squares solution of the Williams eigenfunction expansion for displacements in a cracked body. Discrete values of the influence function, evaluated using the crack surface displacements, are curve fit using an assumed functional form. The assumed functional form includes appropriate limit-behavior terms for very deep and very shallow cracks. Continuous representation of the influence function provides a convenient means for evaluating stress-intensity factors for arbitrary stress distributions by numerical integration. The procedure is demonstrated for an edge-cracked strip and a radially cracked disk. Comparisons with available published results demonstrate the accuracy of the procedure.

Anion-π Catalysis on Fullerenes.

PubMed

López-Andarias, Javier; Frontera, Antonio; Matile, Stefan

2017-09-27

Anion-π interactions on fullerenes are about as poorly explored as the use of fullerenes in catalysis. However, strong exchange-correlation contributions and the localized π holes on their surface promise unique selectivities. To elaborate on this promise, tertiary amines are attached nearby. Dependent on their positioning, the resulting stabilization of anionic transition states on fullerenes is shown to accelerate disfavored enolate addition and exo Diels-Alder reactions enantioselectively. The found selectivities are consistent with computational simulations, particularly concerning the discrimination of differently planarized and charge-delocalized enolate tautomers by anion-π interactions. Enolate-π interactions on fullerenes are much shorter than standard π-π interactions and anion-π interactions on planar surfaces, and alternative cation-π interactions are not observed. These findings open new perspectives with regard to anion-π interactions in general and the use of carbon allotropes in catalysis.

Liners for ion transport membrane systems

DOEpatents

Carolan, Michael Francis; Miller, Christopher Francis

2010-08-10

Ion transport membrane system comprising (a) a pressure vessel comprising an interior, an exterior, an inlet, an inlet conduit, an outlet, and an outlet conduit; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein the inlet and the outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; (c) a gas manifold having an interior surface wherein the gas manifold is in flow communication with the interior region of each of the planar ion transport membrane modules and with the exterior of the pressure vessel; and (d) a liner disposed within any of the inlet conduit, the outlet conduit, and the interior surface of the gas manifold.

Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kaul, R.; Taylor, S.; Myers, G.; Sharma, A.

2003-01-01

Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.

Surface thermodynamics of planar, cylindrical, and spherical vapour-liquid interfaces of water

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

Lau, Gabriel V.; Müller, Erich A.; Jackson, George

2015-03-21

The test-area (TA) perturbation approach has been gaining popularity as a methodology for the direct computation of the interfacial tension in molecular simulation. Though originally implemented for planar interfaces, the TA approach has also been used to analyze the interfacial properties of curved liquid interfaces. Here, we provide an interpretation of the TA method taking the view that it corresponds to the change in free energy under a transformation of the spatial metric for an affine distortion. By expressing the change in configurational energy of a molecular configuration as a Taylor expansion in the distortion parameter, compact relations are derivedmore » for the interfacial tension and its energetic and entropic components for three different geometries: planar, cylindrical, and spherical fluid interfaces. While the tensions of the planar and cylindrical geometries are characterized by first-order changes in the energy, that of the spherical interface depends on second-order contributions. We show that a greater statistical uncertainty is to be expected when calculating the thermodynamic properties of a spherical interface than for the planar and cylindrical cases, and the evaluation of the separate entropic and energetic contributions poses a greater computational challenge than the tension itself. The methodology is employed to determine the vapour-liquid interfacial tension of TIP4P/2005 water at 293 K by molecular dynamics simulation for planar, cylindrical, and spherical geometries. A weak peak in the curvature dependence of the tension is observed in the case of cylindrical threads of condensed liquid at a radius of about 8 Å, below which the tension is found to decrease again. In the case of spherical drops, a marked decrease in the tension from the planar limit is found for radii below ∼ 15 Å; there is no indication of a maximum in the tension with increasing curvature. The vapour-liquid interfacial tension tends towards the planar limit for large system sizes for both the cylindrical and spherical cases. Estimates of the entropic and energetic contributions are also evaluated for the planar and cylindrical geometries and their magnitudes are in line with the expectations of our simple analysis.« less

Epitaxial growth of GaSb on V-grooved Si (001) substrates with an ultrathin GaAs stress relaxing layer

NASA Astrophysics Data System (ADS)

Li, Qiang; Lai, Billy; Lau, Kei May

2017-10-01

We report epitaxial growth of GaSb nano-ridge structures and planar thin films on V-groove patterned Si (001) substrates by leveraging the aspect ratio trapping technique. GaSb was deposited on {111} Si facets of the V-shaped trenches using metal-organic chemical vapor deposition with a 7 nm GaAs growth initiation layer. Transmission electron microscopy analysis reveals the critical role of the GaAs layer in providing a U-shaped surface for subsequent GaSb epitaxy. A network of misfit dislocations was uncovered at the GaSb/GaAs hetero-interface. We studied the evolution of the lattice relaxation as the growth progresses from closely pitched GaSb ridges to coalesced thin films using x-ray diffraction. The omega rocking curve full-width-at-half-maximum of the resultant GaSb thin film is among the lowest values reported by molecular beam epitaxy, substantiating the effectiveness of the defect necking mechanism. These results thus present promising opportunities for the heterogeneous integration of devices based on 6.1 Å family compound semiconductors.

Porous aluminum room temperature anodizing process in a fluorinated-oxalic acid solution

NASA Astrophysics Data System (ADS)

Dhahri, S.; Fazio, E.; Barreca, F.; Neri, F.; Ezzaouia, H.

2016-08-01

Anodizing of aluminum is used for producing porous insulating films suitable for different applications in electronics and microelectronics. Porous-type aluminum films are most simply realized by galvanostatic anodizing in aqueous acidic solutions. The improvement in application of anodizing technique is associated with a substantial reduction of the anodizing voltage at appropriate current densities as well as to the possibility to carry out the synthesis process at room temperature in order to obtain a self-planarizing dielectric material incorporated in array of super-narrow metal lines. In this work, the anodizing of aluminum to obtain porous oxide was carried out, at room temperature, on three different substrates (glass, stainless steel and aluminum), using an oxalic acid-based electrolyte with the addition of a relatively low amount of 0.4 % of HF. Different surface morphologies, from nearly spherical to larger porous nanostructures with smooth edges, were observed by means of scanning electron microscopy. These evidences are explained by considering the formation, transport and adsorption of the fluorine species which react with the Al3+ ions. The behavior is also influenced by the nature of the original substrate.

Particle Collection Efficiency of a Lens-Liquid Filtration System

NASA Astrophysics Data System (ADS)

Wong, Ross Y. M.; Ng, Moses L. F.; Chao, Christopher Y. H.; Li, Z. G.

2011-09-01

Clinical and epidemiological studies have shown that indoor air quality has substantial impact on the health of building occupants [1]. Possible sources of indoor air contamination include hazardous gases as well as particulate matters (PMs) [2]. Experimental studies show that the size distribution of PMs in indoor air ranges from tens of nanometers to a few hundreds of micrometers [3]. Vacuum cleaners can be used as a major tool to collect PMs from floor/carpets, which are the main sources of indoor PMs. However, the particle collection efficiency of typical cyclonic filters in the vacuums drops significantly for particles of diameter below 10 μm. In this work, we propose a lens-liquid filtration system (see Figure 1), where the flow channel is formed by a liquid free surface and a planar plate with fin/lens structures. Computational fluid dynamics simulations are performed by using FLUENT to optimize the structure of the proposed system toward high particle collection efficiency and satisfactory pressure drop. Numerical simulations show that the system can collect 250 nm diameter particles with collection efficiency of 50%.

Recent advances of conductive nanocomposites in printed and flexible electronics

NASA Astrophysics Data System (ADS)

Khan, Saleem; Lorenzelli, Leandro

2017-08-01

Conductive nanocomposites have emerged as significant smart engineered materials for realizing flexible electronics on diverse substrates in recent years. Conductive nanocomposites are comprised of conductive fillers mixed with polymeric elastomer (e.g. polydimethylsiloxane). The possibility to tune electrical as well as mechanical properties of nanocomposites makes them suitable for a wide spectrum of applications including sensors and electronics on non-planar and stretchable surfaces. A number of conductive nanofillers and manufacturing technologies have been developed to meet the diverse requirements of various applications. Considering the substantial contribution of conductive nanocomposites, it is opportune time to review the potentials of various nanofillers, their synthesis, processing methodologies and challenges associated to them. This paper reviews conductive nanocomposites, especially in context with their use in the development of electronic components and the sensors exploiting the piezoresistive behavior. The paper is structured around the nanocomposites related studies aiming to develop various building blocks of flexible electronic skin systems such as pressure, touch, strain and temperature sensors as well as stretchable interconnects. Besides this, the use of nanocomposites in other stimulating industrial and biomedical applications has also been explored briefly.

An energy-based equilibrium contact angle boundary condition on jagged surfaces for phase-field methods.

PubMed

Frank, Florian; Liu, Chen; Scanziani, Alessio; Alpak, Faruk O; Riviere, Beatrice

2018-08-01

We consider an energy-based boundary condition to impose an equilibrium wetting angle for the Cahn-Hilliard-Navier-Stokes phase-field model on voxel-set-type computational domains. These domains typically stem from μCT (micro computed tomography) imaging of porous rock and approximate a (on μm scale) smooth domain with a certain resolution. Planar surfaces that are perpendicular to the main axes are naturally approximated by a layer of voxels. However, planar surfaces in any other directions and curved surfaces yield a jagged/topologically rough surface approximation by voxels. For the standard Cahn-Hilliard formulation, where the contact angle between the diffuse interface and the domain boundary (fluid-solid interface/wall) is 90°, jagged surfaces have no impact on the contact angle. However, a prescribed contact angle smaller or larger than 90° on jagged voxel surfaces is amplified. As a remedy, we propose the introduction of surface energy correction factors for each fluid-solid voxel face that counterbalance the difference of the voxel-set surface area with the underlying smooth one. The discretization of the model equations is performed with the discontinuous Galerkin method. However, the presented semi-analytical approach of correcting the surface energy is equally applicable to other direct numerical methods such as finite elements, finite volumes, or finite differences, since the correction factors appear in the strong formulation of the model. Copyright © 2018 Elsevier Inc. All rights reserved.

Near-planar TS waves and longitudinal vortices in channel flow: Nonlinear interaction and focusing

NASA Technical Reports Server (NTRS)

Hall, P.; Smith, F. T.

1989-01-01

The nonlinear interaction between planar or near-planar Tollmien-Schlichting waves and longitudinal vortices, induced or input, is considered theoretically for channel flows at high Reynolds numbers. Several kinds of nonlinear interaction, dependent on the input amplitudes and wavenumbers or on previously occurring interactions, are found and inter-related. The first, Type 1, is studied the most here and it usually produces spanwise focusing of both the wave and the vortex motion, within a finite scaled time, along with enhancement of both their amplitudes. This then points to the nonlinear interaction Type 2 where new interactive effects come into force to drive the wave and the vortex nonlinearly. Types 3, 4 correspond to still higher amplitudes, with 3 being related to 2, while 4 is connected with a larger-scale interaction 5 studied in an allied paper. Both 3, 4 are subsets of the full three-dimensional triple-deck-lie interaction, 6. The strongest nonlinear interactions are those of 4, 5, 6 since they alter the mean-flow profile substantially, i.e., by an 0(1) relative amount. All the types of nonlinear interaction however can result in the formation of focussed responses in the sense of spanwise concentrations and/or amplifications of vorticity and wave amplitude.

Critique of Sikkink and Keane's comparison of surface fuel sampling techniques

Treesearch

Clinton S. Wright; Roger D. Ottmar; Robert E. Vihnanek

2010-01-01

The 2008 paper of Sikkink and Keane compared several methods to estimate surface fuel loading in western Montana: two widely used inventory techniques (planar intersect and fixed-area plot) and three methods that employ photographs as visual guides (photo load, photoload macroplot and photo series). We feel, however, that their study design was inadequate to evaluate...

Extraction of MOS VLSI (Very-Large-Scale-Integrated) Circuit Models Including Critical Interconnect Parasitics.

DTIC Science & Technology

1987-09-01

can be reduced substantially, compared to using numerical methods to model inter - " connect parasitics. Although some accuracy might be lost with...conductor widths and spacings listed in Table 2 1 , have been employed for simulation. In the first set of the simulations, planar dielectric inter ...model, there are no restrictions on the iumber ol diele-iric and conductors. andl the shape of the conductors and the dielectric inter - a.e,, In the

Iridium-catalyzed direct tetraborylation of perylene bisimides.

PubMed

Teraoka, Takuro; Hiroto, Satoru; Shinokubo, Hiroshi

2011-05-20

Treatment of perylene bisimides (PBIs) with bis(pinacolato)diboron in the presence of an iridium catalyst provides tetraborylated PBIs at 2,5,8,11-positions in good yields with perfect regioselectivity. The planar structure of the perylene core has been confirmed by X-ray diffraction analysis. Oxidation of tetraborylated PBI with hydroxylamine hydrochloride affords tetrahydroxy PBI in excellent yield, which exhibits a substantially blue-shifted absorption spectrum due to an intramolecular hydrogenbonding interaction between carbonyl and hydroxy groups.

Defect reduction in seeded aluminum nitride crystal growth

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

Bondokov, Robert T.; Morgan, Kenneth E.; Schowalter, Leo J.

2017-04-18

Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density.ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

Defect reduction in seeded aluminum nitride crystal growth

DOEpatents

Bondokov, Robert T.; Morgan, Kenneth E.; Schowalter, Leo J.; Slack, Glen A.

2017-06-06

Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density .ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

Defect reduction in seeded aluminum nitride crystal growth

DOEpatents

Bondokov, Robert T.; Schowalter, Leo J.; Morgan, Kenneth; Slack, Glen A; Rao, Shailaja P.; Gibb, Shawn Robert

2017-09-26

Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density.ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells

PubMed Central

Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

2016-01-01

In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm2, an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm2. Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification. PMID:27185635

A preference for edgewise interactions between aromatic rings and carboxylate anions: the biological relevance of anion-quadrupole interactions.

PubMed

Jackson, Michael R; Beahm, Robert; Duvvuru, Suman; Narasimhan, Chandrasegara; Wu, Jun; Wang, Hsin-Neng; Philip, Vivek M; Hinde, Robert J; Howell, Elizabeth E

2007-07-19

Noncovalent interactions are quite important in biological structure-function relationships. To study the pairwise interaction of aromatic amino acids (phenylalanine, tyrosine, tryptophan) with anionic amino acids (aspartic and glutamic acids), small molecule mimics (benzene, phenol or indole interacting with formate) were used at the MP2 level of theory. The overall energy associated with an anion-quadrupole interaction is substantial (-9.5 kcal/mol for a benzene-formate planar dimer at van der Waals contact distance), indicating the electropositive ring edge of an aromatic group can interact with an anion. Deconvolution of the long-range coplanar interaction energy into fractional contributions from charge-quadrupole interactions, higher-order electrostatic interactions, and polarization terms was achieved. The charge-quadrupole term contributes between 30 to 45% of the total MP2 benzene-formate interaction; most of the rest of the interaction arises from polarization contributions. Additional studies of the Protein Data Bank (PDB Select) show that nearly planar aromatic-anionic amino acid pairs occur more often than expected from a random angular distribution, while axial aromatic-anionic pairs occur less often than expected; this demonstrates the biological relevance of the anion-quadrupole interaction. While water may mitigate the strength of these interactions, they may be numerous in a typical protein structure, so their cumulative effect could be substantial.

Velocity Inversion In Cylindrical Couette Gas Flows

NASA Astrophysics Data System (ADS)

Dongari, Nishanth; Barber, Robert W.; Emerson, David R.; Zhang, Yonghao; Reese, Jason M.

2012-05-01

We investigate a power-law probability distribution function to describe the mean free path of rarefied gas molecules in non-planar geometries. A new curvature-dependent model is derived by taking into account the boundary-limiting effects on the molecular mean free path for surfaces with both convex and concave curvatures. In comparison to a planar wall, we find that the mean free path for a convex surface is higher at the wall and exhibits a sharper gradient within the Knudsen layer. In contrast, a concave wall exhibits a lower mean free path near the surface and the gradients in the Knudsen layer are shallower. The Navier-Stokes constitutive relations and velocity-slip boundary conditions are modified based on a power-law scaling to describe the mean free path, in accordance with the kinetic theory of gases, i.e. transport properties can be described in terms of the mean free path. Velocity profiles for isothermal cylindrical Couette flow are obtained using the power-law model. We demonstrate that our model is more accurate than the classical slip solution, especially in the transition regime, and we are able to capture important non-linear trends associated with the non-equilibrium physics of the Knudsen layer. In addition, we establish a new criterion for the critical accommodation coefficient that leads to the non-intuitive phenomena of velocity-inversion. Our results are compared with conventional hydrodynamic models and direct simulation Monte Carlo data. The power-law model predicts that the critical accommodation coefficient is significantly lower than that calculated using the classical slip solution and is in good agreement with available DSMC data. Our proposed constitutive scaling for non-planar surfaces is based on simple physical arguments and can be readily implemented in conventional fluid dynamics codes for arbitrary geometric configurations.

Enhancement in sample collection for the detection of MDMA using a novel planar SPME (PSPME) device coupled to ion mobility spectrometry (IMS).

PubMed

Gura, Sigalit; Guerra-Diaz, Patricia; Lai, Hanh; Almirall, José R

2009-07-01

Trace detection of illicit drugs challenges the scientific community to develop improved sensitivity and selectivity in sampling and detection techniques. Ion mobility spectrometry (IMS) is one of the prominent trace detectors for illicit drugs and explosives, mostly due to its portability, high sensitivity and fast analysis. Current sampling methods for IMS rely on wiping suspected surfaces or withdrawing air through filters to collect particulates. These methods depend greatly on the particulates being bound onto surfaces or having sufficient vapour pressure to be airborne. Many of these compounds are not readily available in the headspace due to their low vapour pressure. This research presents a novel SPME device for enhanced air sampling and shows the use of optimized IMS by genetic algorithms to target volatile markers and/or odour signatures of illicit substances. The sampling method was based on unique static samplers, planar substrates coated with sol-gel polydimethyl siloxane (PDMS) nanoparticles, also known as planar solid-phase microextraction (PSPME). Due to its surface chemistry, high surface area and capacity, PSPME provides significant increases in sensitivity over conventional fibre SPME. The results show a 50-400 times increase in the detection capacity for piperonal, the odour signature of 3,4-methylenedioxymethamphetamine (MDMA). The PSPME-IMS technique was able to detect 600 ng of piperonal in a 30 s extraction from a quart-sized can containing 5 MDMA tablets, while detection using fibre SPME-IMS was not attainable. In a blind study of six cases suspected to contain varying amounts of MDMA in the tablets, PSPME-IMS successfully detected five positive cases and also produced no false positives or false negatives. One positive case had minimal amounts of MDMA resulting in a false negative response for fibre SPME-IMS.

Tortuous path chemical preconcentrator

DOEpatents

Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Wheeler, David R.; Simonson, Robert J.

2010-09-21

A non-planar, tortuous path chemical preconcentrator has a high internal surface area having a heatable sorptive coating that can be used to selectively collect and concentrate one or more chemical species of interest from a fluid stream that can be rapidly released as a concentrated plug into an analytical or microanalytical chain for separation and detection. The non-planar chemical preconcentrator comprises a sorptive support structure having a tortuous flow path. The tortuosity provides repeated twists, turns, and bends to the flow, thereby increasing the interfacial contact between sample fluid stream and the sorptive material. The tortuous path also provides more opportunities for desorption and readsorption of volatile species. Further, the thermal efficiency of the tortuous path chemical preconcentrator is comparable or superior to the prior non-planar chemical preconcentrator. Finally, the tortuosity can be varied in different directions to optimize flow rates during the adsorption and desorption phases of operation of the preconcentrator.

Planar edge Schottky barrier-tunneling transistors using epitaxial graphene/SiC junctions.

PubMed

Kunc, Jan; Hu, Yike; Palmer, James; Guo, Zelei; Hankinson, John; Gamal, Salah H; Berger, Claire; de Heer, Walt A

2014-09-10

A purely planar graphene/SiC field effect transistor is presented here. The horizontal current flow over one-dimensional tunneling barrier between planar graphene contact and coplanar two-dimensional SiC channel exhibits superior on/off ratio compared to conventional transistors employing vertical electron transport. Multilayer epitaxial graphene (MEG) grown on SiC(0001̅) was adopted as the transistor source and drain. The channel is formed by the accumulation layer at the interface of semi-insulating SiC and a surface silicate that forms after high vacuum high temperature annealing. Electronic bands between the graphene edge and SiC accumulation layer form a thin Schottky barrier, which is dominated by tunneling at low temperatures. A thermionic emission prevails over tunneling at high temperatures. We show that neglecting tunneling effectively causes the temperature dependence of the Schottky barrier height. The channel can support current densities up to 35 A/m.

Compact cladding-pumped planar waveguide amplifier and fabrication method

DOEpatents

Bayramian, Andy J.; Beach, Raymond J.; Honea, Eric; Murray, James E.; Payne, Stephen A.

2003-10-28

A low-cost, high performance cladding-pumped planar waveguide amplifier and fabrication method, for deployment in metro and access networks. The waveguide amplifier has a compact monolithic slab architecture preferably formed by first sandwich bonding an erbium-doped core glass slab between two cladding glass slabs to form a multi-layer planar construction, and then slicing the construction into multiple unit constructions. Using lithographic techniques, a silver stripe is deposited and formed at a top or bottom surface of each unit construction and over a cross section of the bonds. By heating the unit construction in an oven and applying an electric field, the silver stripe is then ion diffused to increase the refractive indices of the core and cladding regions, with the diffusion region of the core forming a single mode waveguide, and the silver diffusion cladding region forming a second larger waveguide amenable to cladding pumping with broad area diodes.

Power module packaging with double sided planar interconnection and heat exchangers

DOEpatents

Liang, Zhenxian; Marlino, Laura D.; Ning, Puqi; Wang, Fei

2015-05-26

A double sided cooled power module package having a single phase leg topology includes two IGBT and two diode semiconductor dies. Each IGBT die is spaced apart from a diode semiconductor die, forming a switch unit. Two switch units are placed in a planar face-up and face-down configuration. A pair of DBC or other insulated metallic substrates is affixed to each side of the planar phase leg semiconductor dies to form a sandwich structure. Attachment layers are disposed on outer surfaces of the substrates and two heat exchangers are affixed to the substrates by rigid bond layers. The heat exchangers, made of copper or aluminum, have passages for carrying coolant. The power package is manufactured in a two-step assembly and heating process where direct bonds are formed for all bond layers by soldering, sintering, solid diffusion bonding or transient liquid diffusion bonding, with a specially designed jig and fixture.

CMOS chip planarization by chemical mechanical polishing for a vertically stacked metal MEMS integration

NASA Astrophysics Data System (ADS)

Lee, Hocheol; Miller, Michele H.; Bifano, Thomas G.

2004-01-01

In this paper we present the planarization process of a CMOS chip for the integration of a microelectromechanical systems (MEMS) metal mirror array. The CMOS chip, which comes from a commercial foundry, has a bumpy passivation layer due to an underlying aluminum interconnect pattern (1.8 µm high), which is used for addressing individual micromirror array elements. To overcome the tendency for tilt error in the CMOS chip planarization, the approach is to sputter a thick layer of silicon nitride at low temperature and to surround the CMOS chip with dummy silicon pieces that define a polishing plane. The dummy pieces are first lapped down to the height of the CMOS chip, and then all pieces are polished. This process produced a chip surface with a root-mean-square flatness error of less than 100 nm, including tilt and curvature errors.

Graphene as a transparent conducting and surface field layer in planar Si solar cells.

PubMed

Kumar, Rakesh; Mehta, Bodh R; Bhatnagar, Mehar; S, Ravi; Mahapatra, Silika; Salkalachen, Saji; Jhawar, Pratha

2014-01-01

This work presents an experimental and finite difference time domain (FDTD) simulation-based study on the application of graphene as a transparent conducting layer on a planar and untextured crystalline p-n silicon solar cell. A high-quality monolayer graphene with 97% transparency and 350 Ω/□ sheet resistance grown by atmospheric pressure chemical vapor deposition method was transferred onto planar Si cells. An increase in efficiency from 5.38% to 7.85% was observed upon deposition of graphene onto Si cells, which further increases to 8.94% upon SiO2 deposition onto the graphene/Si structure. A large increase in photon conversion efficiency as a result of graphene deposition shows that the electronic interaction and the presence of an electric field at the graphene/Si interface together play an important role in this improvement and additionally lead to a reduction in series resistance due to the conducting nature of graphene.

Alignment of nematic liquid crystals by inhomogeneous surfaces

NASA Astrophysics Data System (ADS)

Ong, Hiap Liew; Hurd, Alan J.; Meyer, Robert B.

1985-01-01

Variable oblique alignment of nematic liquid crystals has been achieved on microscopically inhomogeneous surfaces. The surfaces consist of small patches favoring vertical (homeotropic) alignment surrounded by a matrix favoring a planar alignment. The construction of these surfaces employs randomly distributed microscopic metal islands formed by certain metals as vapor-deposited films. Larger scale periodic patterns were made as well to verify the techniques. The results are interpreted in terms of a continuum elasticity theory and azimuthal degeneracy is also discussed.

Effects of GlidArc plasma treatment on metallic surface

NASA Astrophysics Data System (ADS)

Astanei, D.; Ursache, M.; Hnatiuc, E.; Stoica, I.; Hnatiuc, B.; Felea, C.

2016-12-01

This paper presents the GlidArc plasma effects on some metallic surfaces often used in dentistry: zirconium, titanium and nickel - chromium alloy plates. For the experiments performed, a GlidArc reactor with two planar electrodes has been used. During the tests, the gas flow has been kept constant while the treatment time and the distance between the plasma and the sample were modified. The surfaces were analyzed using atomic force microscopy (AFM) in order to determine the surface morphological modifications induced by the plasma treatment.

Bio-inspired photo-electronic material based on photosynthetic proteins

NASA Astrophysics Data System (ADS)

Lebedev, Nikolai; Trammell, Scott A.; Tsoi, Stanislav; Spano, Anthony; Kim, Jin Ho; Xu, Jimmy; Twigg, Mark E.; Schnur, Joel M.

2009-08-01

The construction of efficient light energy converting (photovoltaic and photo-electronic) devices is a current and great challenge in science and technology and one that will have important economic consequences. Several innovative nanoelectronic materials were proposed to achieve this goal, semiconductor quantum dots, metallic nanowires and carbon nanotubes (CNT) are among them. As a charge separating unit for light energy conversion, we propose the utilization of the most advanced photoelectronic material developed by nature, photosynthetic reaction center proteins. As a first step in this direction, we constructed a novel bioinorganic nanophotoelectronic material with photoactive photosynthetic reaction center (RC) proteins encapsulated inside a multiwall CNT arrayed electrode. The material consists of photosynthetic RC-cytochrome complexes acting as charge separating units bound to the inner walls of a CNT electrode and ubiquinone-10 (Q2) serving as a soluble electron-transfer mediator to the counter electrode. The proteins were immobilized inside carbon nanotubes by a Ni(NTA)-alkane-pyrene linker, forming a self-assembled monolayer (SAM) on the surface of inner CNT walls and allowing for unidirectional protein orientation. The material demonstrates an enhanced photoinduced electron transfer rate and shows substantial improvement in photocurrent density compared to that obtained with the same proteins when immobilized on planar graphite (HOPG) electrode. The results suggest that protein encapsulation in precisely organized arrayed tubular electrode architecture can considerably improve the performance of photovoltaic, photoelectronic, or biofuel cell devices. They demonstrate the potential for substantial advantages of precisely organized nano electrode tubular arrayed architecture for variety biotechnological applications.

Stacked multilayers of alternating reduced graphene oxide and carbon nanotubes for planar supercapacitors.

PubMed

Moon, Geon Dae; Joo, Ji Bong; Yin, Yadong

2013-12-07

A simple layer-by-layer approach has been developed for constructing 2D planar supercapacitors of multi-stacked reduced graphene oxide and carbon nanotubes. This sandwiched 2D architecture enables the full utilization of the maximum active surface area of rGO nanosheets by using a CNT layer as a porous physical spacer to enhance the permeation of a gel electrolyte inside the structure and reduce the agglomeration of rGO nanosheets along the vertical direction. As a result, the stacked multilayers of rGO and CNTs are capable of offering higher output voltage and current production.

Squeezed-light generation in a nonlinear planar waveguide with a periodic corrugation

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

Perina, Jan Jr.; Haderka, Ondrej; Sibilia, Concita

Two-mode nonlinear interaction (second-harmonic and second-subharmonic generation) in a planar waveguide with a small periodic corrugation at the surface is studied. Scattering of the interacting fields on the corrugation leads to constructive interference that enhances the nonlinear process provided that all the interactions are phase matched. Conditions for the overall phase matching are found. Compared with a perfectly quasi-phase-matched waveguide, better values of squeezing as well as higher intensities are reached under these conditions. Procedure for finding optimum values of parameters for squeezed-light generation is described.

High-Accuracy Near-Surface Large-Eddy Simulation with Planar Topography

DTIC Science & Technology

2015-08-03

Navier-Stokes equation, in effect randomizing the subfilter-scale (SFS) stress divergence. In the intervening years it has been discovered that this...surface stress models do introduce spurious effects that force deviations from LOTW at the first couple grid levels adjacent to the surface. Fig. 10 shows...SFS stress is sufficiently overwhelming to produce the overshoot. When the LES is moved into the HAZ so that the viscous effects causing the

Stacked multilayers of alternating reduced graphene oxide and carbon nanotubes for planar supercapacitors

NASA Astrophysics Data System (ADS)

Moon, Geon Dae; Joo, Ji Bong; Yin, Yadong

2013-11-01

A simple layer-by-layer approach has been developed for constructing 2D planar supercapacitors of multi-stacked reduced graphene oxide and carbon nanotubes. This sandwiched 2D architecture enables the full utilization of the maximum active surface area of rGO nanosheets by using a CNT layer as a porous physical spacer to enhance the permeation of a gel electrolyte inside the structure and reduce the agglomeration of rGO nanosheets along the vertical direction. As a result, the stacked multilayers of rGO and CNTs are capable of offering higher output voltage and current production.A simple layer-by-layer approach has been developed for constructing 2D planar supercapacitors of multi-stacked reduced graphene oxide and carbon nanotubes. This sandwiched 2D architecture enables the full utilization of the maximum active surface area of rGO nanosheets by using a CNT layer as a porous physical spacer to enhance the permeation of a gel electrolyte inside the structure and reduce the agglomeration of rGO nanosheets along the vertical direction. As a result, the stacked multilayers of rGO and CNTs are capable of offering higher output voltage and current production. Electronic supplementary information (ESI) available: Experimental details, SEM and TEM images and additional electrochemical data. See DOI: 10.1039/c3nr04339h

Stacked thin layers of metaphase chromatin explain the geometry of chromosome rearrangements and banding.

PubMed

Daban, Joan-Ramon

2015-10-08

The three-dimensional organization of tightly condensed chromatin within metaphase chromosomes has been one of the most challenging problems in structural biology since the discovery of the nucleosome. This study shows that chromosome images obtained from typical banded karyotypes and from different multicolour cytogenetic analyses can be used to gain information about the internal structure of chromosomes. Chromatin bands and the connection surfaces in sister chromatid exchanges and in cancer translocations are planar and orthogonal to the chromosome axis. Chromosome stretching produces band splitting and even the thinnest bands are orthogonal and well defined, indicating that short stretches of DNA can occupy completely the chromosome cross-section. These observations impose strong physical constraints on models that attempt to explain chromatin folding in chromosomes. The thin-plate model, which consists of many stacked layers of planar chromatin perpendicular to the chromosome axis, is compatible with the observed orientation of bands, with the existence of thin bands, and with band splitting; it is also compatible with the orthogonal orientation and planar geometry of the connection surfaces in chromosome rearrangements. The results obtained provide a consistent interpretation of the chromosome structural properties that are used in clinical cytogenetics for the diagnosis of hereditary diseases and cancers.

NMR of thin layers using a meanderline surface coil

DOEpatents

Cowgill, Donald F.

2001-01-01

A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

Effects of captopril, losartan, and nifedipine on cell hypertrophy of cultured vascular smooth muscle from hypertensive Ren-2 transgenic rats

PubMed Central

Peiró, Concepción; Llergo, José L; Angulo, Javier; López-Novoa, José M; Rodríguez-López, Ana; Rodríguez-Mañas, Leocadio; Sánchez-Ferrer, Carlos F

1997-01-01

We hypothesized that tissular renin-angotensin system (RAS) induces vascular hypertrophy in hypertensive Ren-2 transgenic rats (TGR; strain name TGR(mRen2)L27). This assumption was tested in cell cultures of vascular smooth muscle (VSMC) from both hypertensive TGR and control normotensive Sprague-Dawley (SD) rats. Planar cell surface area, protein synthesis, and protein content per cell were studied, the role for locally produced angiotensin II (AII) was evaluated and the possible pharmacological interference by different drugs was analysed. By use of radioimmunoassay techniques, AII could be determined in TGR cultures (10.25±0.12 pg per 107 cells) while it could not be detected in SD ones. Under serum-free conditions, VSMC from hypertensive TGR were hypertrophic when compared to SD VSMC, as they presented a higher protein content per cell (335±18 and 288±7 pg per cell respectively; P<0.05) and increased mean planar cell surface area, as determined by image analysis (4,074±238 and 4,764±204 μm2, respectively; P<0.05). When exogenously added to cultured SD and TGR VSMC, AII (100 pM to 1 μM) promoted protein synthesis and protein content in a concentration-dependent manner without affecting DNA synthesis. Maximal effects were observed at 100 nM. At this concentration, AII effectively increased planar cell surface area in both SD and TGR cultures by ∼20%. Treatment of TGR cultures, in the absence of exogenous AII, with the angiotensin-converting enzyme inhibitor captopril or the angiotensin AT1 receptors antagonist losartan (100 nM to 10 μM) reduced planar cell surface area in a concentration-dependent manner. In addition, both captopril and losartan (10 μM), decreased protein synthesis by ∼15%. Treatment of SD VSMC, in the absence of exogenous AII, with both captopril and losartan had no effect either on planar cell surface area or protein synthesis. Treatment with the Ca2+ antagonist nifedipine (100 nM to 10 μM) reduced cell size in both SD and TGR cultures. Maximal cell reduction reached by nifedipine averaged 906±58 and 1,292±57 μm2, in SD and TGR, respectively (P<0.05). In addition, nifedipine, nitrendipine and nisoldipine (all at 10 μM) decreased protein synthesis in both cell types by 15–25%. We concluded that cultured VSMC from TGR are hypertrophic in comparison with those from SD. This cell hypertrophy can be the consequence of the expression of the transgene Ren-2 that activates a tissular RAS and locally produces AII, which acts in a paracrine, autocrine, or intracrine manner. Cell hypertrophy in TGR cultures could be selectively reduced by RAS blockade, while nifedipine decreased cell size and protein synthesis in both hypertrophic and non hypertrophic cells. PMID:9257925

Radiation Pattern of Chair Armed Microstrip Antenna

NASA Astrophysics Data System (ADS)

Mishra, Rabindra Kishore; Sahu, Kumar Satyabrat

2016-12-01

This work analyzes planar antenna conformable to chair arm shaped surfaces for WLAN application. Closed form expressions for its radiation pattern are developed and validated using measurements on prototype and commercial EM code at 2.4 GHz.

Automatic segmentation of the liver using multi-planar anatomy and deformable surface model in abdominal contrast-enhanced CT images

NASA Astrophysics Data System (ADS)

Jang, Yujin; Hong, Helen; Chung, Jin Wook; Yoon, Young Ho

2012-02-01

We propose an effective technique for the extraction of liver boundary based on multi-planar anatomy and deformable surface model in abdominal contrast-enhanced CT images. Our method is composed of four main steps. First, for extracting an optimal volume circumscribing a liver, lower and side boundaries are defined by positional information of pelvis and rib. An upper boundary is defined by separating the lungs and heart from CT images. Second, for extracting an initial liver volume, optimal liver volume is smoothed by anisotropic diffusion filtering and is segmented using adaptively selected threshold value. Third, for removing neighbor organs from initial liver volume, morphological opening and connected component labeling are applied to multiple planes. Finally, for refining the liver boundaries, deformable surface model is applied to a posterior liver surface and missing left robe in previous step. Then, probability summation map is generated by calculating regional information of the segmented liver in coronal plane, which is used for restoring the inaccurate liver boundaries. Experimental results show that our segmentation method can accurately extract liver boundaries without leakage to neighbor organs in spite of various liver shape and ambiguous boundary.

Planar SiC MEMS flame ionization sensor for in-engine monitoring

NASA Astrophysics Data System (ADS)

Rolfe, D. A.; Wodin-Schwartz, S.; Alonso, R.; Pisano, A. P.

2013-12-01

A novel planar silicon carbide (SiC) MEMS flame ionization sensor was developed, fabricated and tested to measure the presence of a flame from the surface of an engine or other cooled surface while withstanding the high temperature and soot of a combustion environment. Silicon carbide, a ceramic semiconductor, was chosen as the sensor material because it has low surface energy and excellent mechanical and electrical properties at high temperatures. The sensor measures the conductivity of scattered charge carriers in the flame's quenching layer. This allows for flame detection, even when the sensor is situated several millimetres from the flame region. The sensor has been shown to detect the ionization of premixed methane and butane flames in a wide temperature range starting from room temperature. The sensors can measure both the flame chemi-ionization and the deposition of water vapour on the sensor surface. The width and speed of a premixed methane laminar flame front were measured with a series of two sensors fabricated on a single die. This research points to the feasibility of using either single sensors or arrays in internal combustion engine cylinders to optimize engine performance, or for using sensors to monitor flame stability in gas turbine applications.

Direct optical measurement of light coupling into planar waveguide by plasmonic nanoparticles.

PubMed

Pennanen, Antti M; Toppari, J Jussi

2013-01-14

Coupling of light into a thin layer of high refractive index material by plasmonic nanoparticles has been widely studied for application in photovoltaic devices, such as thin-film solar cells. In numerous studies this coupling has been investigated through measurement of e.g. quantum efficiency or photocurrent enhancement. Here we present a direct optical measurement of light coupling into a waveguide by plasmonic nanoparticles. We investigate the coupling efficiency into the guided modes within the waveguide by illuminating the surface of a sample, consisting of a glass slide coated with a high refractive index planar waveguide and plasmonic nanoparticles, while directly measuring the intensity of the light emitted out of the waveguide edge. These experiments were complemented by transmittance and reflectance measurements. We show that the light coupling is strongly affected by thin-film interference, localized surface plasmon resonances of the nanoparticles and the illumination direction (front or rear).

Enhanced proton acceleration by intense laser interaction with an inverse cone target

NASA Astrophysics Data System (ADS)

Bake, Muhammad Ali; Aimidula, Aimierding; Xiaerding, Fuerkaiti; Rashidin, Reyima

2016-08-01

The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface induce a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.

Continuous planar phospholipid bilayer supported on porous silicon thin film reflector.

PubMed

Cunin, Frédérique; Milhiet, Pierre-Emmanuel; Anglin, Emily; Sailor, Michael J; Espenel, Cédric; Le Grimellec, Christian; Brunel, Daniel; Devoisselle, Jean-Marie

2007-10-01

Reconstituting artificial membranes for in vitro studies of cell barrier mechanisms and properties is of major interest in biology. Here, artificial membranes supported on porous silicon photonic crystal reflectors are prepared and investigated. The materials are of interest for label-free probing of supported membrane events such as protein binding, molecular recognition, and transport. The porous silicon substrates are prepared as multilayered films consisting of a periodically varying porosity, with pore dimensions of a few nanometers in size. Planar phospholipid bilayers are deposited on the topmost surface of the oxidized hydrophilic mesoporous silicon films. Atomic force microscopy provides evidence of continuous bilayer deposition at the surface, and optical measurements indicate that the lipids do not significantly infiltrate the porous region. The presence of the supported bilayer does not obstruct the optical spectrum from the porous silicon layer, suggesting that the composite structures can act as effective optical biosensors.

Full Wave Analysis of RF Signal Attenuation in a Lossy Rough Surface Cave using a High Order Time Domain Vector Finite Element Method

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

Pingenot, J; Rieben, R; White, D

2005-10-31

We present a computational study of signal propagation and attenuation of a 200 MHz planar loop antenna in a cave environment. The cave is modeled as a straight and lossy random rough wall. To simulate a broad frequency band, the full wave Maxwell equations are solved directly in the time domain via a high order vector finite element discretization using the massively parallel CEM code EMSolve. The numerical technique is first verified against theoretical results for a planar loop antenna in a smooth lossy cave. The simulation is then performed for a series of random rough surface meshes in ordermore » to generate statistical data for the propagation and attenuation properties of the antenna in a cave environment. Results for the mean and variance of the power spectral density of the electric field are presented and discussed.« less

Enhanced proton acceleration by intense laser interaction with an inverse cone target

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

Bake, Muhammad Ali; Aimidula, Aimierding, E-mail: amir@mail.bnu.edu.cn; Xiaerding, Fuerkaiti

The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface inducemore » a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.« less

Modeling a photoinduced planar-to-homeotropic anchoring transition triggered by surface azobenzene units in a nematic liquid crystal

NASA Astrophysics Data System (ADS)

Oswald, Patrick; Ignés-Mullol, Jordi

2017-09-01

The performance of light-controlled liquid crystal anchoring surfaces depends on the nature of the photosensitive moieties and on the concentration of spacer units. Here, we study the kinetics of photosensitive liquid crystal cells that incorporate an azobenzene-based self-assembled monolayer. We characterize the photoinduced homeotropic-to-planar transition and the subsequent reverse relaxation in terms of the underlying isomerization of the photosensitive layer. We show that the response time can be precisely adjusted by tuning the lateral packing of azobenzene units by means of inert spacer molecules. Using simple kinetic assumptions and a well-known model for the energetics of liquid crystal anchoring we are able to capture the details of the optical microscopy experimental observations. Our analysis provides fitted values for all the relevant material parameters, including the zenithal and the azimuthal anchoring strength.

Metallic and Magnetic 2D Materials Containing Planar Tetracoordinated C and N.

PubMed

Jimenez-Izal, Elisa; Saeys, Mark; Alexandrova, Anastassia N

2016-08-26

The top monolayers of surface carbides and nitrides of Co and Ni are predicted to yield new stable 2D materials upon exfoliation. These 2D phases are p4g clock reconstructed, and contain planar tetracoordinated C or N. The stability of these flat carbides and nitrides is high, and ab-initio molecular dynamics at a simulation temperature of 1800 K suggest that the materials are thermally stable at elevated temperatures. The materials owe their stability to local triple aromaticity (π-, σ-radial, and σ-peripheral) associated with binding of the main group element to the metal. All predicted 2D phases are conductors, and the two alloys of Co are also ferromagnetic - a property especially rare among 2D materials. The preparation of 2D carbides and nitrides is envisioned to be done through surface deposition and peeling, possibly on a metal with a larger lattice constant for reduced affinity.

Characteristics of Planar Monopole Antenna on High Impedance Electromagnetic Surface

NASA Technical Reports Server (NTRS)

Scardelletti, Maximilian C.; Jastram, Nathan; Ponchak, George E.; Franklin, Rhonda R.

2011-01-01

This paper presents for the first time measured characteristics of a planar monopole antenna placed directly on a high impedance electromagnetic surface or artificial magnetic conductor (AMC). The return loss and radiation patterns are compared between the antenna in free space, and when placed directly on a perfect electrical conductor (PEC), and on the AMC. The antenna measured in free space has a wide pass band from 3 to 10 GHz. The return loss for the antenna on the PEC is nearly all reflected back and the return loss for the antenna on the AMC has a 10 dB bandwidth from 7.5 to 9.5 GHz. The gain of the antenna in free space, on PEC and on AMC is 1, -12 and 10 dBi, respectively. This indicates that the AMC is working properly, sending all the radiation outward with little loss.

Microwave background distortions from domain walls

NASA Technical Reports Server (NTRS)

Goetz, Guenter; Noetzold, Dirk

1990-01-01

Domain walls arising in a cosmic phase transition after decoupling were recently proposed as seeds for the formation of large scale structure. The distortion induced in the microwave background radiation is calculated in dependence of the wall thickness, surface density, scalar field potential, cosmic redshift and the velocity of the wall. It was found that the maximal redshift distortion for both spherical and planar walls is of the order pi G sigma H(sup -1)(sub 0), where sigma is the surface energy density and H(sup -1)(sub 0) the Hubble parameter. It was also found that, for a wall thickness smaller than the horizon, walls can be treated as infinitely thin, i.e., the redshift distortion is independent of the wall thickness and the specific form of the scalar potential. For planar walls moving with a Lorentz-factor gamma the redshift distortion is enhanced by gamma cubed.

Diffraction of a shock wave by a compression corner; regular and single Mach reflection

NASA Technical Reports Server (NTRS)

Vijayashankar, V. S.; Kutler, P.; Anderson, D.

1976-01-01

The two dimensional, time dependent Euler equations which govern the flow field resulting from the injection of a planar shock with a compression corner are solved with initial conditions that result in either regular reflection or single Mach reflection of the incident planar shock. The Euler equations which are hyperbolic are transformed to include the self similarity of the problem. A normalization procedure is employed to align the reflected shock and the Mach stem as computational boundaries to implement the shock fitting procedure. A special floating fitting scheme is developed in conjunction with the method of characteristics to fit the slip surface. The reflected shock, the Mach stem, and the slip surface are all treated as harp discontinuities, thus, resulting in a more accurate description of the inviscid flow field. The resulting numerical solutions are compared with available experimental data and existing first-order, shock-capturing numerical solutions.

Fabrication and optimization of a whiskerless Schottky barrier diode for submillimeter wave applications

NASA Technical Reports Server (NTRS)

Bishop, W.; Mattauch, R. J.

1990-01-01

The following accomplishments were made towards the goal of an optimized whiskerless diode chip for submillimeter wavelength applications. (1) Surface channel whiskerless diode structure was developed which offers excellent DC and RF characteristics, reduced shunt capacitance and simplified fabrication compared to mesa and proton isolated structures. (2) Reliable fabrication technology was developed for the surface channel structure. The new anode plating technology is a major improvement. (3) DC and RF characterization of the surface channel diode was compared with whisker contacted diodes. This data indicates electrical performance as good as the best reported for similar whisker contacted devices. (4) Additional batches of surface channel diodes were fabricated with excellent I-V and reduced shunt capacitance. (5) Large scale capacitance modelinng was done for the planar diode structure. This work revealed the importance of removing the substrate gallium arsenide for absolute minimum pad capacitance. (6) A surface channel diode was developed on quartz substrate and this substrate was completely removed after diode mounting for minimum parasitic capacitance. This work continues with the goal of producing excellent quality submillimeter wavelength planar diodes which satisfy the requirements of easy handling and robustness. These devices will allow the routine implementation of Schottky receivers into space-based applications at frequencies as high as 1 THz, and, in the future, beyond.

Constructing polyamidoamine dendrons from poly(poly(ethylene glycol) monomethacrylate) brushes grafted from planar silicon hydride surfaces for biomedical applications

NASA Astrophysics Data System (ADS)

Liu, Xiang; Zheng, Hong-Ning; Yan, Qin; Wang, Cuie; Ma, Yin-Zhou; Tang, Yan-Chun; Xiao, Shou-Jun

2011-06-01

A facile approach was established to construct polyamidoamine (PAMAM) dendrons from polymer brushes of poly(poly(ethylene glycol) monomethacrylate) (Si-g-P(PEGMA-OH)) grafted from a planar silicon hydride surface. First the Si-g-P(PEGMA-OH) brushes were grown via surface-initiated atom transfer radical polymerization with robust Si-C links on silicon surfaces. The side-chain hydroxyl groups of Si-g-P(PEGMA-OH) were chlorinated with thionyl chloride and further chlorines were substituted with amino groups of ethylenediamine, giving terminal primary amines. Borrowing the solution synthesis approach, we constructed second and third generations of PAMAM dendrons on-chip by surface-initiated alternative growth of two monomers, methyl acrylate and ethylenediamine. Two applications of silicon-based PAMAM dendrons were shown: the dense amino groups were activated via a cross-linker, N-succinimidyl-6-maleimidylhexanoate, to capture a free-thiol-carrying peptide of oxytocin and the third generation of PAMAM dendrons was used as a platform to on-chip synthesize a three amino acid peptide of Arg-Gly-Asp (RGD). The above conclusions were mainly derived from a home-built multiple transmission-reflection infrared spectroscopy, and complemented by X-ray photoelectron spectroscopy, UV-Vis spectroscopy and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry.

Orbital selective spin-texture in a topological insulator

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

Singh, Bahadur, E-mail: bahadursingh24@gmail.com; Prasad, R.

Three-dimensional topological insulators support a metallic non-trivial surface state with unique spin texture, where spin and momentum are locked perpendicular to each other. In this work, we investigate the orbital selective spin-texture associated with the topological surface states in Sb2Te{sub 3}, using the first principles calculations. Sb2Te{sub 3} is a strong topological insulator with a p-p type bulk band inversion at the Γ-point and supports a single topological metallic surface state with upper (lower) Dirac-cone has left (right) handed spin-texture. Here, we show that the topological surface state has an additional locking between the spin and orbitals, leading to anmore » orbital selective spin-texture. The out-of-plane orbitals (p{sub z} orbitals) have an isotropic orbital texture for both the Dirac cones with an associated left and right handed spin-texture for the upper and lower Dirac cones, respectively. In contrast, the in-planar orbital texture (p{sub x} and p{sub y} projections) is tangential for the upper Dirac-cone and is radial for the lower Dirac-cone surface state. The dominant in-planar orbital texture in both the Dirac cones lead to a right handed orbital-selective spin-texture.« less

Chemical-mechanical planarization of aluminum and copper interconnects with magnetic liners

NASA Astrophysics Data System (ADS)

Wang, Bin

2000-10-01

Chemical Mechanical Planarization (CMP) has been employed to achieve Damascene patterning of aluminum and copper interconnects with unique magnetic liners. A one-step process was developed for each interconnect scheme, using a double-layered pad with mesh cells, pores, and perforations on a top hard layer. In a hydrogen peroxide-based slurry, aluminum CMP was a process of periodic removal and formation of a surface oxide layer. Cu CMP in the same slurry, however, was found to be a dissolution dominant process. In a potassium iodate-based slurry, copper removal was the result of two competing reactions: copper dissolution and a non-native surface layer formation. Guided by electrochemistry, slurries were developed to remove nickel in different regimes of the corrosion kinetics diagram. Nickel CMP in a ferric sulfate-based slurry resulted in periodic removal and formation of a passive surface layer. In a potassium permanganate-based slurry, nickel removal is a dissolution dominant process. Visible Al(Cu) surface damages obtained with copper-doped aluminum could be eliminated by understanding the interactions between the substrate, the pad, and the abrasive agglomerate. Increasing substrate hardness by annealing prior to CMP led to a surface finish free of visible scratches. A similar result was also obtained by preventing formation of abrasive agglomerates and minimizing their contact with the substrate.

Experimental Study of Floating-Gate-Type Metal-Oxide-Semiconductor Capacitors with Nanosize Triangular Cross-Sectional Tunnel Areas for Low Operating Voltage Flash Memory Application

NASA Astrophysics Data System (ADS)

Liu, Yongxun; Guo, Ruofeng; Kamei, Takahiro; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Ishikawa, Yuki; Hayashida, Tetsuro; Sakamoto, Kunihiro; Ogura, Atsushi; Masahara, Meishoku

2012-06-01

The floating-gate (FG)-type metal-oxide-semiconductor (MOS) capacitors with planar (planar-MOS) and three-dimensional (3D) nanosize triangular cross-sectional tunnel areas (3D-MOS) have successfully been fabricated by introducing rapid thermal oxidation (RTO) and postdeposition annealing (PDA), and their electrical characteristics between the control gate (CG) and FG have been systematically compared. It was experimentally found in both planar- and 3D-MOS capacitors that the uniform and higher breakdown voltages are obtained by introducing RTO owing to the high-quality thermal oxide formation on the surface and etched edge regions of the n+ polycrystalline silicon (poly-Si) FG, and the leakage current is highly suppressed after PDA owing to the improved quality of the tetraethylorthosilicate (TEOS) silicon dioxide (SiO2) between CG and FG. Moreover, a lower breakdown voltage between CG and FG was obtained in the fabricated 3D-MOS capacitors as compared with that of planar-MOS capacitors thanks to the enhanced local electric field at the tips of triangular tunnel areas. The developed nanosize triangular cross-sectional tunnel area is useful for the fabrication of low operating voltage flash memories.

A novel ultra-planar, long-stroke and low-voltage piezoelectric micromirror

NASA Astrophysics Data System (ADS)

Bakke, Thor; Vogl, Andreas; Żero, Oleg; Tyholdt, Frode; Johansen, Ib-Rune; Wang, Dag

2010-06-01

A novel piston-type micromirror with a stroke of up to 20 µm at 20 V formed out of a silicon-on-insulator wafer with integrated piezoelectric actuators was designed, fabricated and characterized. The peak-to-valley planarity of a 2 mm diameter mirror was better than 15 nm, and tip-to-tip tilt upon actuation less than 30 nm. A resonance frequency of 9.8 kHz was measured. Analytical and finite element models were developed and compared to measurements. The design is based on a silicon-on-insulator wafer where the circular mirror is formed out of the handle silicon, thus forming a thick, highly rigid and ultra-planar mirror surface. The mirror plate is connected to a supporting frame through a membrane formed out of the device silicon layer. A piezoelectric actuator made of lead-zirconate-titanate (PZT) thin film is structured on top of the membrane, providing mirror deflection by deformation of the membrane. Two actuator designs were tested: one with a single ring and the other with a double ring providing bidirectional movement of the mirror. The fabricated mirrors were characterized by white light interferometry to determine the static and temporal response as well as mirror planarity.

Progress in low light-level InAs detectors- towards Geiger-mode detection

NASA Astrophysics Data System (ADS)

Tan, Chee Hing; Ng, Jo Shien; Zhou, Xinxin; David, John; Zhang, Shiyong; Krysa, Andrey

2017-05-01

InAs avalanche photodiodes (APDs) can be designed such that only electrons are allowed to initiate impact ionization, leading to the lowest possible excess noise factor. Optimization of wet chemical etching and surface passivation produced mesa APDs with bulk dominated dark current and responsivity that are comparable and higher, respectively, than a commercial InAs detector. Our InAs electron-APDs also show high stability with fluctuation of 0.1% when operated at a gain of 11.2 over 60 s. These InAs APDs can detect very weak signal down to 35 photons per pulse. Fabrication of planar InAs by Be implantation produced planar APDs with bulk dominated dark current. Annealing at 550 °C was necessary to remove implantation damage and to activate Be dopants. Due to minimal diffusion of Be, thick depletion of 8 μm was achieved. Since the avalanche gain increases exponentially with the thickness of avalanche region, our planar APD achieved high gain > 300 at 200 K. Our work suggest that both mesa and planar InAs APDs can exhibit high gain. When combined with a suitable preamplifier, single photon detection using InAs electron-APDs could be achieved.

Elegant Face-Down Liquid-Space-Restricted Deposition of CsPbBr3 Films for Efficient Carbon-Based All-Inorganic Planar Perovskite Solar Cells.

PubMed

Teng, Pengpeng; Han, Xiaopeng; Li, Jiawei; Xu, Ya; Kang, Lei; Wang, Yangrunqian; Yang, Ying; Yu, Tao

2018-03-21

It is a great challenge to obtain the uniform films of bromide-rich perovskites such as CsPbBr 3 in the two-step sequential solution process (two-step method), which was mainly due to the decomposition of the precursor films in solution. Herein, we demonstrated a novel and elegant face-down liquid-space-restricted deposition to inhibit the decomposition and fabricate high-quality CsPbBr 3 perovskite films. This method is highly reproducible, and the surface of the films was smooth and uniform with an average grain size of 860 nm. As a consequence, the planar perovskite solar cells (PSCs) without the hole-transport layer based on CsPbBr 3 and carbon electrodes exhibit enhanced power conversion efficiency (PCE) along with high open circuit voltage ( V OC ). The champion device has achieved a PCE of 5.86% with a V OC of 1.34 V, which to our knowledge is the highest performing CsPbBr 3 PSC in planar structure. Our results suggest an efficient and low-cost route to fabricate the high-quality planar all-inorganic PSCs.

The directed self-assembly for the surface patterning by electron beam II

NASA Astrophysics Data System (ADS)

Nakagawa, Sachiko T.

2015-03-01

When a low-energy electron beam (EB) or a low-energy ion beam (IB) irradiates a crystal of zincblende (ZnS)-type as crystalline Si (c-Si), a very similar {311} planar defect is often observed. Here, we used a molecular dynamics simulation for a c-Si that included uniformly distributed Frenkel-pairs, assuming a wide beam and sparse distribution of defects caused by each EB. We observed the formation of ? linear defects, which agglomerate to form planar defects labeled with the Miller index {311} as well as the case of IB irradiation. These were identified by a crystallographic analysis called pixel mapping (PM) method. The PM had suggested that self-interstitial atoms may be stabilized on a specific frame of a lattice made of invisible metastable sites in the ZnS-type crystal. This agglomeration appears as {311} planar defects. It was possible at a much higher temperature than room temperature,for example, at 1000 K. This implies that whatever disturbance may bring many SIAs in a ZnS-type crystal, elevated lattice vibration promotes self-organization of the SIAs to form {311} planar defects according to the frame of metastable lattice as is guided by a chart presented by crystallography.

Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs.

PubMed

Campbell, Gavin P; Mannix, Andrew J; Emery, Jonathan D; Lee, Tien-Lin; Guisinger, Nathan P; Hersam, Mark C; Bedzyk, Michael J

2018-05-09

Atomically thin two-dimensional (2D) materials exhibit superlative properties dictated by their intralayer atomic structure, which is typically derived from a limited number of thermodynamically stable bulk layered crystals (e.g., graphene from graphite). The growth of entirely synthetic 2D crystals, those with no corresponding bulk allotrope, would circumvent this dependence upon bulk thermodynamics and substantially expand the phase space available for structure-property engineering of 2D materials. However, it remains unclear if synthetic 2D materials can exist as structurally and chemically distinct layers anchored by van der Waals (vdW) forces, as opposed to strongly bound adlayers. Here, we show that atomically thin sheets of boron (i.e., borophene) grown on the Ag(111) surface exhibit a vdW-like structure without a corresponding bulk allotrope. Using X-ray standing wave-excited X-ray photoelectron spectroscopy, the positions of boron in multiple chemical states are resolved with sub-angström spatial resolution, revealing that the borophene forms a single planar layer that is 2.4 Å above the unreconstructed Ag surface. Moreover, our results reveal that multiple borophene phases exhibit these characteristics, denoting a unique form of polymorphism consistent with recent predictions. This observation of synthetic borophene as chemically discrete from the growth substrate suggests that it is possible to engineer a much wider variety of 2D materials than those accessible through bulk layered crystal structures.

The interface of SrTiO3 and H2O from density functional theory molecular dynamics

PubMed Central

Spijker, P.; Foster, A. S.

2016-01-01

We use dispersion-corrected density functional theory molecular dynamics simulations to predict the ionic, electronic and vibrational properties of the SrTiO3/H2O solid–liquid interface. Approximately 50% of surface oxygens on the planar SrO termination are hydroxylated at all studied levels of water coverage, the corresponding number being 15% for the planar TiO2 termination and 5% on the stepped TiO2-terminated surface. The lateral ordering of the hydration structure is largely controlled by covalent-like surface cation to H2O bonding and surface corrugation. We find a featureless electronic density of states in and around the band gap energy region at the solid–liquid interface. The vibrational spectrum indicates redshifting of the O–H stretching band due to surface-to-liquid hydrogen bonding and blueshifting due to high-frequency stretching vibrations of OH fragments within the liquid, as well as strong suppression of the OH stretching band on the stepped surface. We find highly varying rates of proton transfer above different SrTiO3 surfaces, owing to differences in hydrogen bond strength and the degree of dissociation of incident water. Trends in proton dynamics and the mode of H2O adsorption among studied surfaces can be explained by the differential ionicity of the Ti–O and Sr–O bonds in the SrTiO3 crystal. PMID:27713660

Study of phase-locked diode laser array and DFB/DBR surface emitting laser diode

NASA Astrophysics Data System (ADS)

Hsin, Wei

New types of phased-array and surface-emitting lasers are designed. The importance and approaches (or structures) of different phased array and surface emitting laser diodes are reviewed. The following are described: (1) a large optical cavity channel substrate planar laser array with layer thickness chirping; (2) a vertical cavity surface emitter with distributed feedback (DFB) optical cavity and a transverse junction buried heterostructure; (3) a microcavity distributed Bragg reflector (DBR) surface emitter; and (4) two surface emitting laser structures which utilized lateral current injection schemes to overcome the problems occurring in the vertical injection scheme.

Crack Growth Mechanisms under Anti-Plane Shear in Composite Laminates

NASA Astrophysics Data System (ADS)

Horner, Allison Lynne

The research conducted for this dissertation focuses on determining the mechanisms associated with crack growth in polymer matrix composite laminates subjected to anti-plane shear (mode III) loading. For mode III split-beam test methods were proposed, and initial evaluations were conducted. A single test method was selected for further evaluation. Using this test method, it was determined that the apparent mode III delamination toughness, GIIIc , depended on geometry, which indicated a true material property was not being measured. Transverse sectioning and optical microscopy revealed an array of transverse matrix cracks, or echelon cracks, oriented at approximately 45° and intersecting the plane of the delamination. Subsequent investigations found the echelon array formed prior to the onset of planar delamination advance and that growth of the planar delamination is always coupled to echelon array formation in these specimens. The evolution of the fracture surfaces formed by the echelon array and planar delamination were studied, and it was found that the development was similar to crack growth in homogenous materials subjected to mode III or mixed mode I-III loading, although the composite laminate architecture constrained the fracture surface development differently than homogenous materials. It was also found that, for split-beam specimens such as those used herein, applying an anti-plane shear load results in twisting of the specimen's uncracked region which gives rise to a mixed-mode I-III load condition. This twisting has been related to the apparent mode III toughness as well as the orientation of the transverse matrix cracks. A finite element model was then developed to study the mechanisms of initial echelon array formation. From this, it is shown that an echelon array will develop, but will become self-limiting prior to the onset of planar delamination growth.

Microfluidic step-emulsification in axisymmetric geometry.

PubMed

Chakraborty, I; Ricouvier, J; Yazhgur, P; Tabeling, P; Leshansky, A M

2017-10-25

Biphasic step-emulsification (Z. Li et al., Lab Chip, 2015, 15, 1023) is a promising microfluidic technique for high-throughput production of μm and sub-μm highly monodisperse droplets. The step-emulsifier consists of a shallow (Hele-Shaw) microchannel operating with two co-flowing immiscible liquids and an abrupt expansion (i.e., step) to a deep and wide reservoir. Under certain conditions the confined stream of the disperse phase, engulfed by the co-flowing continuous phase, breaks into small highly monodisperse droplets at the step. Theoretical investigation of the corresponding hydrodynamics is complicated due to the complex geometry of the planar device, calling for numerical approaches. However, direct numerical simulations of the three dimensional surface-tension-dominated biphasic flows in confined geometries are computationally expensive. In the present paper we study a model problem of axisymmetric step-emulsification. This setup consists of a stable core-annular biphasic flow in a cylindrical capillary tube connected co-axially to a reservoir tube of a larger diameter through a sudden expansion mimicking the edge of the planar step-emulsifier. We demonstrate that the axisymmetric setup exhibits similar regimes of droplet generation to the planar device. A detailed parametric study of the underlying hydrodynamics is feasible via inexpensive (two dimensional) simulations owing to the axial symmetry. The phase diagram quantifying the different regimes of droplet generation in terms of governing dimensionless parameters is presented. We show that in qualitative agreement with experiments in planar devices, the size of the droplets generated in the step-emulsification regime is independent of the capillary number and almost insensitive to the viscosity ratio. These findings confirm that the step-emulsification regime is solely controlled by surface tension. The numerical predictions are in excellent agreement with in-house experiments with the axisymmetric step-emulsifier.

Attachment of second harmonic-active moiety to molecules for detection of molecules at interfaces

DOEpatents

Salafsky, Joshua S.; Eisenthal, Kenneth B.

2005-10-11

This invention provides methods of detecting molecules at an interface, which comprise labeling the molecules with a second harmonic-active moiety and detecting the labeled molecules at the interface using a surface selective technique. The invention also provides methods for detecting a molecule in a medium and for determining the orientation of a molecular species within a planar surface using a second harmonic-active moiety and a surface selective technique.

Intermolecular Casimir-Polder forces in water and near surfaces

NASA Astrophysics Data System (ADS)

Thiyam, Priyadarshini; Persson, Clas; Sernelius, Bo E.; Parsons, Drew F.; Malthe-Sørenssen, Anders; Boström, Mathias

2014-09-01

The Casimir-Polder force is an important long-range interaction involved in adsorption and desorption of molecules in fluids. We explore Casimir-Polder interactions between methane molecules in water, and between a molecule in water near SiO2 and hexane surfaces. Inclusion of the finite molecular size in the expression for the Casimir-Polder energy leads to estimates of the dispersion contribution to the binding energies between molecules and between one molecule and a planar surface.

The Visual Representation of 3D Object Orientation in Parietal Cortex

PubMed Central

Cowan, Noah J.; Angelaki, Dora E.

2013-01-01

An accurate representation of three-dimensional (3D) object orientation is essential for interacting with the environment. Where and how the brain visually encodes 3D object orientation remains unknown, but prior studies suggest the caudal intraparietal area (CIP) may be involved. Here, we develop rigorous analytical methods for quantifying 3D orientation tuning curves, and use these tools to the study the neural coding of surface orientation. Specifically, we show that single neurons in area CIP of the rhesus macaque jointly encode the slant and tilt of a planar surface, and that across the population, the distribution of preferred slant-tilts is not statistically different from uniform. This suggests that all slant-tilt combinations are equally represented in area CIP. Furthermore, some CIP neurons are found to also represent the third rotational degree of freedom that determines the orientation of the image pattern on the planar surface. Together, the present results suggest that CIP is a critical neural locus for the encoding of all three rotational degrees of freedom specifying an object's 3D spatial orientation. PMID:24305830

Methylammonium lead mixed halide films processed with a new composition for planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Park, Ban-Suk; Lee, Seojun; Yoon, Saemon; Ha, Tae-Jun; Kang, Dong-Won

2018-01-01

In this work, we propose a new mixed halide precursor composition for MAPbI3-xClx organic/inorganic perovskite (PRV) solar cells. PRV films made with a new precursor composition of (MAI: PbCl2: PbI2 = 2 : 1 : 1) could be crystallized at lower temperature (70 °C) and shorter annealing duration (60 min), whereas previous standard composition (MAI: PbCl2 = 3 : 1) requires multi-step and high temperature (from 75 °C to 130 °C) annealing for longer durations (∼100 min). By adopting the suggested composition, much uniform surface morphology of PRV light harvester was obtained even though non-polar solvent washing was not introduced yet. Also, when the suitable toluene washing treatment was introduced, PRV surfaces of highly compact and large crystallites with regular distribution were achieved without any pinhole, which offered significant improvements in fill factor (41 → 65%) and power conversion efficiency (5.85 → 9.39%) of PRV cells. The suggested new precursor composition contributing for surface topography can be widely utilized for inverted planar PRV devices with low-temperature and simple processing.

Scalable planar fabrication processes for chalcogenide-based topological insulators

NASA Astrophysics Data System (ADS)

Sharma, Peter; Henry, M. David; Douglas, Erica; Wiwi, Michael; Lima Sharma, Ana; Lewis, Rupert; Sugar, Joshua; Salehi, Maryam; Koirala, Nikesh; Oh, Seongshik

Surface currents in topological insulators are expected to have long spin diffusion lengths, which could lead to numerous applications. Experiments that show promising transport properties were conducted on exfoliated flakes from bulk material, thin films on substrates of limited dimensions, or bulk material, with limited yield. A planar thin film-based technology is needed to make topological insulator devices at scale and could also lead to new device designs. We address two problems related to fabricating chalcogenide-based topological insulator devices on 3'' wafers in the Sandia Microfabrication Facility using Bi2Te3 films. (2) Implantation damage and its subsequent mitigation through annealing is characterized. (2) The degradation in dielectric layers used to manipulate surface potential for elucidating topological surface state transport is characterized under different processing conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000. Funded by the Office of Naval Research (N0001416IP00098-0).

Persistent Hall voltages across thin planar charged quantum rings on the surface of a topological insulator

NASA Astrophysics Data System (ADS)

Durganandini, P.

2015-03-01

We consider thin planar charged quantum rings on the surface of a three dimensional topological insulator coated with a thin ferromagnetic layer. We show theoretically, that when the ring is threaded by a magnetic field, then, due to the Aharanov-Bohm effect, there are not only the well known circulating persistent currents in the ring but also oscillating persistent Hall voltages across the thin ring. Such oscillating persistent Hall voltages arise due to the topological magneto-electric effect associated with the axion electrodynamics exhibited by the surface electronic states of the three dimensional topological insulator when time reversal symmetry is broken. We further generalize to the case of dipole currents and show that analogous Hall dipole voltages arise. We also discuss the robustness of the effect and suggest possible experimental realizations in quantum rings made of semiconductor heterostructures. Such experiments could also provide new ways of observing the predicted topological magneto-electric effect in three dimensional topological insulators with time reversal symmetry breaking. I thank BCUD, Pune University, Pune for financial support through research grant.

Monte Carlo modelling of large scale NORM sources using MCNP.

PubMed

Wallace, J D

2013-12-01

The representative Monte Carlo modelling of large scale planar sources (for comparison to external environmental radiation fields) is undertaken using substantial diameter and thin profile planar cylindrical sources. The relative impact of source extent, soil thickness and sky-shine are investigated to guide decisions relating to representative geometries. In addition, the impact of source to detector distance on the nature of the detector response, for a range of source sizes, has been investigated. These investigations, using an MCNP based model, indicate a soil cylinder of greater than 20 m diameter and of no less than 50 cm depth/height, combined with a 20 m deep sky section above the soil cylinder, are needed to representatively model the semi-infinite plane of uniformly distributed NORM sources. Initial investigation of the effect of detector placement indicate that smaller source sizes may be used to achieve a representative response at shorter source to detector distances. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Constant pressure high throughput membrane permeation testing system

DOEpatents

Albenze, Erik J.; Hopkinson, David P.; Luebke, David R.

2014-09-02

The disclosure relates to a membrane testing system for individual evaluation of a plurality of planar membranes subjected to a feed gas on one side and a sweep gas on a second side. The membrane testing system provides a pressurized flow of a feed and sweep gas to each membrane testing cell in a plurality of membrane testing cells while a stream of retentate gas from each membrane testing cell is ported by a retentate multiport valve for sampling or venting, and a stream of permeate gas from each membrane testing cell is ported by a permeate multiport valve for sampling or venting. Back pressure regulators and mass flow controllers act to maintain substantially equivalent gas pressures and flow rates on each side of the planar membrane throughout a sampling cycle. A digital controller may be utilized to position the retentate and permeate multiport valves cyclically, allowing for gas sampling of different membrane cells over an extended period of time.

Planar fuel cell utilizing nail current collectors for increased active surface area

DOEpatents

George, Thomas J.; Meacham, G. B. Kirby

2002-03-26

A plurality of nail current collector members are useful in the gas flow passages of an electrochemical device to optimize the active surfaces of the device and to provide structural support. In addition, the thicknesses of cathode and anode layers within the electrochemical device are varied according to current flow through the device to reduce resistance and increase operating efficiency.

Planar fuel cell utilizing nail current collectors for increased active surface area

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

George, Thomas J.; Meacham, G.B. Kirby

1999-11-26

A plurality of nail current collector members are useful in the gas flow passages of an electrochemical device to optimize the active surfaces of the device and to provide structural support. In addition, the thicknesses of cathode and anode layers within the electrochemical device are varied according to current flow through the device to reduce resistance and increase operating efficiency.

Ceramic capacitor exhibiting graceful failure by self-clearing, method for fabricating self-clearing capacitor

DOEpatents

Kaufman, David Y [Chicago, IL; Saha, Sanjib [Santa Clara, CA

2006-08-29

A short-resistant capacitor comprises an electrically conductive planar support substrate having a first thickness, a ceramic film deposited over the support substrate, thereby defining a ceramic surface; and a metallic film deposited over the ceramic surface, said film having a second thickness which is less than the first thickness and which is between 0.01 and 0.1 microns.

Physics-Based Imaging Methods for Terahertz Nondestructive Evaluation Applications

NASA Astrophysics Data System (ADS)

Kniffin, Gabriel Paul

Lying between the microwave and far infrared (IR) regions, the "terahertz gap" is a relatively unexplored frequency band in the electromagnetic spectrum that exhibits a unique combination of properties from its neighbors. Like in IR, many materials have characteristic absorption spectra in the terahertz (THz) band, facilitating the spectroscopic "fingerprinting" of compounds such as drugs and explosives. In addition, non-polar dielectric materials such as clothing, paper, and plastic are transparent to THz, just as they are to microwaves and millimeter waves. These factors, combined with sub-millimeter wavelengths and non-ionizing energy levels, makes sensing in the THz band uniquely suited for many NDE applications. In a typical nondestructive test, the objective is to detect a feature of interest within the object and provide an accurate estimate of some geometrical property of the feature. Notable examples include the thickness of a pharmaceutical tablet coating layer or the 3D location, size, and shape of a flaw or defect in an integrated circuit. While the material properties of the object under test are often tightly controlled and are generally known a priori, many objects of interest exhibit irregular surface topographies such as varying degrees of curvature over the extent of their surfaces. Common THz pulsed imaging (TPI) methods originally developed for objects with planar surfaces have been adapted for objects with curved surfaces through use of mechanical scanning procedures in which measurements are taken at normal incidence over the extent of the surface. While effective, these methods often require expensive robotic arm assemblies, the cost and complexity of which would likely be prohibitive should a large volume of tests be needed to be carried out on a production line. This work presents a robust and efficient physics-based image processing approach based on the mature field of parabolic equation methods, common to undersea acoustics, seismology, and other areas of science and engineering. The method allows the generation of accurate 3D THz tomographic images of objects with irregular, non-planar surfaces using a simple planar scan geometry, thereby facilitating the integration of 3D THz imaging into mainstream NDE use.

Tunable geometric Fano resonances in a metal/insulator stack

NASA Astrophysics Data System (ADS)

Grotewohl, Herbert

We present a theoretical analysis of surface-plasmon-mediated mode-coupling in a planar thin film metal/insulator stack. The spatial overlap of a surface plasmon polariton (SPP) and a waveguide mode results in a Fano interference analog. Tuning of the material parameters effects the modes and output fields of the system. Lastly, the intensity and phase sensitivity of the system are compared to a standard surface plasmon resonance (SPR). We begin with background information on Fano interference, an interference effect between two indistinguishable pathways. Originally described for autoionization, we discuss the analogs in other systems. We discuss the features of Fano interference in the mode diagrams, and the Fano resonance observed in the output field. The idea of a geometric Fano resonance (GFR) occurring in the angular domain is presented. Background information on surface plasmon polaritons is covered next. The dielectric properties of metals and how they relate to surface plasmons is first reviewed. The theoretical background of SPPs on an infinite planar surface is covered. The modes of a two planar interface metal/insulator stack are reviewed and the leaky properties of the waveguide are shown in the reflectance. We solve for modes of a three interface metal/insulator stack and shows an avoided crossing in the modes indicative of Fano interference. We observe the asymmetric Fano resonance in the angular domain in the reflectance. The tunability of the material parameters tunes the GFR of the system. The GFR tuning is explored and different Fano lineshapes are observed. We also observe a reversal of the asymmetry Fano lineshape, attributed to the relate phase interactions of the non-interacting modes. The phase of the GFR is calculated and discussed for the variations of the parameters. The reflected field is explored as the insulator permittivities are varied. As the waveguide permittivity is varied, we show there is little response from the system. As the exterior permittivity is varied, the reflectance exhibits the geometric Fano resonance and the tunability of the lineshape is explored. Finally, we calculate the sensitivities of our metal/insulator stack to changes in the permittivity and compare them to the sensitivities of SPRs.

Growth of two-dimensional Ge crystal by annealing of heteroepitaxial Ag/Ge(111) under N2 ambient

NASA Astrophysics Data System (ADS)

Ito, Koichi; Ohta, Akio; Kurosawa, Masashi; Araidai, Masaaki; Ikeda, Mitsuhisa; Makihara, Katsunori; Miyazaki, Seiichi

2018-06-01

The growth of a two-dimensional crystal of Ge atoms on an atomically flat Ag(111) surface has been demonstrated by the thermal annealing of a heteroepitaxial Ag/Ge structure in N2 ambient at atmospheric pressure. The surface morphology and chemical bonding features of heteroepitaxial Ag(111) grown on wet-cleaned Ge(111) after annealing at different temperatures and for various times have been systematically investigated to control the surface segregation of Ge atoms and the planarization of the heteroepitaxial Ag(111) surface.

Contact angle determination procedure and detection of an invisible surface film

NASA Technical Reports Server (NTRS)

Meyer, G.; Grat, R.

1990-01-01

The contact angle value, i.e., the tangent angle of liquid resting on a planar solid surface, is a basic parameter which can be applied to a wide range of applications. The goal is to provide a basic understanding of the contact angle measurement technique and to present a simple illustration that can be applied as a quality control method; namely, detection of a surface contaminant which exists on a surface that appears clean to the unaided eye. The equipment and experimental procedures are detailed.

FIBRE AND INTEGRATED OPTICS. OPTICAL PROCESSING OF INFORMATION: Mechanism of lock-in detection with the aid of an alternating field perpendicular to the surface of a planar photorefractive waveguide

NASA Astrophysics Data System (ADS)

Zel'dovich, Boris Ya; Miklyaev, Yu V.; Safonov, V. I.

1995-02-01

An analysis is made of the mechanism of formation of a stationary grating in a planar photorefractive waveguide by a travelling interference pattern with the aid of an alternating electric field applied perpendicular to the waveguide layer. A theoretical calculation is reported of the distribution of the space-charge field in a transverse section of the waveguide. Finite drift lengths and trap saturation are taken into account in these calculations, which are carried out on the assumption of a weak contrast in the interference pattern.

Morse Theory and Relative Equilibria in the Planar n-Vortex Problem

NASA Astrophysics Data System (ADS)

Roberts, Gareth E.

2018-04-01

Morse theoretical ideas are applied to the study of relative equilibria in the planar n-vortex problem. For the case of positive circulations, we prove that the Morse index of a critical point of the Hamiltonian restricted to a level surface of the angular impulse is equal to the number of pairs of real eigenvalues of the corresponding relative equilibrium periodic solution. The Morse inequalities are then used to prove the instability of some families of relative equilibria in the four-vortex problem with two pairs of equal vorticities. We also show that, for positive circulations, relative equilibria cannot accumulate on the collision set.

Condenser-type diffusion denuders for the collection of sulfur dioxide in a cleanroom.

PubMed

Chang, In-Hyoung; Lee, Dong Soo; Ock, Soon-Ho

2003-02-01

High-efficiency condenser-type diffusion denuders of cylindrical and planar geometries are described. The film condensation of water vapor onto a cooled denuder surface can be used as a method for collecting water-soluble gases. By using SO(2) as the test gas, the planar design offers quantitative collection efficiency at air sampling rates up to 5 L min(-1). Coupled to ion chromatography, the limit of detection (LOD) for SO(2) is 0.014 ppbv with a 30-min successive analysis sequence. The method has been successfully applied to the analysis of temperature- and humidity-controlled cleanroom air.

Focusing guided waves using surface bonded elastic metamaterials

NASA Astrophysics Data System (ADS)

Yan, Xiang; Zhu, Rui; Huang, Guoliang; Yuan, Fuh-Gwo

2013-09-01

Bonding a two-dimensional planar array of small lead discs on an aluminum plate with silicone rubber is shown numerically to focus low-frequency flexural guided waves. The "effective mass density profile" of this type of elastic metamaterials (EMMs), perpendicular to wave propagation direction, is carefully tailored and designed, which allows rays of flexural A0 mode Lamb waves to bend in succession and then focus through a 7 × 9 planar array. Numerical simulations show that Lamb waves can be focused beyond EMMs region with amplified displacement and yet largely retained narrow banded waveform, which may have potential application in structural health monitoring.

Two-dimensional complex source point solutions: application to propagationally invariant beams, optical fiber modes, planar waveguides, and plasmonic devices.

PubMed

Sheppard, Colin J R; Kou, Shan S; Lin, Jiao

2014-12-01

Highly convergent beam modes in two dimensions are considered based on rigorous solutions of the scalar wave (Helmholtz) equation, using the complex source point formalism. The modes are applicable to planar waveguide or surface plasmonic structures and nearly concentric microcavity resonator modes in two dimensions. A novel solution is that of a vortex beam, where the direction of propagation is in the plane of the vortex. The modes also can be used as a basis for the cross section of propagationally invariant beams in three dimensions and bow-tie-shaped optical fiber modes.

Efficient planar Sb2S3 solar cells using a low-temperature solution-processed tin oxide electron conductor.

PubMed

Lei, Hongwei; Yang, Guang; Guo, Yaxiong; Xiong, Liangbin; Qin, Pingli; Dai, Xin; Zheng, Xiaolu; Ke, Weijun; Tao, Hong; Chen, Zhao; Li, Borui; Fang, Guojia

2016-06-28

Efficient planar antimony sulfide (Sb2S3) heterojunction solar cells have been made using chemical bath deposited (CBD) Sb2S3 as the absorber, low-temperature solution-processed tin oxide (SnO2) as the electron conductor and poly (3-hexylthiophene) (P3HT) as the hole conductor. A solar conversion efficiency of 2.8% was obtained at 1 sun illumination using a planar device consisting of F-doped SnO2 substrate/SnO2/CBD-Sb2S3/P3HT/Au, whereas the solar cells based on a titanium dioxide (TiO2) electron conductor exhibited a power conversion efficiency of 1.9%. Compared with conventional Sb2S3 sensitized solar cells, the high-temperature processed mesoscopic TiO2 scaffold is no longer needed. More importantly, a low-temperature solution-processed SnO2 layer was introduced for electron transportation to substitute the high-temperature sintered dense blocking TiO2 layer. Our planar solar cells not only have simple geometry with fewer steps to fabricate but also show enhanced performance. The higher efficiency of planar Sb2S3 solar cell devices based on a SnO2 electron conductor is attributed to their high transparency, uniform surface, efficient electron transport properties of SnO2, suitable energy band alignment, and reduced recombination at the interface of SnO2/Sb2S3.

Engineered plant biomass feedstock particles

DOEpatents

Dooley, James H [Federal Way, WA; Lanning, David N [Federal Way, WA; Broderick, Thomas F [Lake Forest Park, WA

2011-10-11

A novel class of flowable biomass feedstock particles with unusually large surface areas that can be manufactured in remarkably uniform sizes using low-energy comminution techniques. The feedstock particles are roughly parallelepiped in shape and characterized by a length dimension (L) aligned substantially with the grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. The particles exhibit a disrupted grain structure with prominent end and surface checks that greatly enhances their skeletal surface area as compared to their envelope surface area. The L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers. The W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers. The L.times.W dimensions define a pair of substantially parallel top surfaces characterized by some surface checking between longitudinally arrayed fibers. The feedstock particles are manufactured from a variety of plant biomass materials including wood, crop residues, plantation grasses, hemp, bagasse, and bamboo.

Shape Effect in the Design of Nanowire Coated Microparticles as Transepithelial Drug Delivery Devices

PubMed Central

Uskoković, Vuk; Lee, Kunwoo; Lee, Phin Peng; Fischer, Kathleen E.; Desai, Tejal A.

2012-01-01

While the oral drug delivery route has traditionally been the most popular among patients, it is estimated that 90 % of therapeutic compounds possess oral bioavailability limitations. Thus, the development of novel drug carriers for more effective oral delivery of therapeutics is an important goal. Composite particles made by growing nanoscopic silicon wires from the surface of narrowly dispersed, microsized silica beads were previously shown to be able to: (a) adhere well onto the epithelium by interdigitating their nanowires with the apical microvilli; and (b) increase the permeability of Caco-2 cell monolayers with respect to small organic molecules in direct proportion to their concentration. A comparison between the effects of spherical and planar particle morphologies on the permeability of the epithelial cell layer in vitro and in vivo presented the subject of this study. Owing to their larger surface area, the planar particles exhibited a higher drug loading efficiency than their spherical counterparts, while simultaneously increasing the transepithelial permeation of a moderately sized model drug, insulin. The insulin elution profile for planar nanowire-coated particles displayed a continual increase in the cumulative amount of the released drug, approaching a constant release rate for 1 – 4 h period of the elution time. An immunohistochemical study confirmed the ability of planar silica particles coated with nanowires to loosen the tight junction of the epithelial cells to a greater extent than the spherical particles did, thus enabling a more facile transport of the drug across the epithelium. Transepithelial permeability tests conducted for model drugs ranging in size from 0.4 to 150 kDa yielded three categories of molecules depending on their permeation propensities. Insulin belonged to the category of molecules deliverable across the epithelium only with the assistance of nanowire-coated particles. Other groups of drugs, smaller and bigger, respectively, either did not need the carrier to permeate the epithelium or were not able to cross it even with the support from the nanowire-coated particles. Bioavailability of insulin orally administered to rabbits was also found to be increased when delivered in conjunction with the nanowire-coated planar particles. PMID:22900471

CAD system for footwear design based on whole real 3D data of last surface

NASA Astrophysics Data System (ADS)

Song, Wanzhong; Su, Xianyu

2000-10-01

Two major parts of application of CAD in footwear design are studied: the development of last surface; computer-aided design of planar shoe-template. A new quasi-experiential development algorithm of last surface based on triangulation approximation is presented. This development algorithm consumes less time and does not need any interactive operation for precisely development compared with other development algorithm of last surface. Based on this algorithm, a software, SHOEMAKERTM, which contains computer aided automatic measurement, automatic development of last surface and computer aide design of shoe-template has been developed.

Thin film photovoltaic cell

DOEpatents

Meakin, John D.; Bragagnolo, Julio

1982-01-01

A thin film photovoltaic cell having a transparent electrical contact and an opaque electrical contact with a pair of semiconductors therebetween includes utilizing one of the electrical contacts as a substrate and wherein the inner surface thereof is modified by microroughening while being macro-planar.

Highly selective surface-wave resonators for terahertz frequency range formed by metallic Bragg gratings

NASA Astrophysics Data System (ADS)

Ginzburg, N. S.; Malkin, A. M.; Sergeev, A. S.; Fil'chenkov, S. E.; Zaslavsky, V. Yu.

2018-04-01

In the frame of the quasi-optical approach we solve the diffraction problem and describe surface modes confined at a metallic plate with a shallow grating of finite length. We prove that such planar grating can form a highly selective surface-wave Bragg resonator. For a given material conductivity and grating length, we find the optimum corrugation depth that provides the maximum value of Q factor. These results are applicable for developing resonators for terahertz frequency bands.

Correcting for surface topography in X-ray fluorescence imaging

PubMed Central

Geil, E. C.; Thorne, R. E.

2014-01-01

Samples with non-planar surfaces present challenges for X-ray fluorescence imaging analysis. Here, approximations are derived to describe the modulation of fluorescence signals by surface angles and topography, and suggestions are made for reducing this effect. A correction procedure is developed that is effective for trace element analysis of samples having a uniform matrix, and requires only a fluorescence map from a single detector. This procedure is applied to fluorescence maps from an incised gypsum tablet. PMID:25343805

Methods of making monolayers

DOEpatents

Alford, Kentin L [Pasco, WA; Simmons, Kevin L [Kennewick, WA; Samuels, William D [Richland, WA; Zemanian, Thomas S [Richland, WA; Liu, Jun [Albuquerque, NM; Shin, Yongsoon [Richland, WA; Fryxell, Glen E [Kennewick, WA

2009-12-08

The invention pertains to methods of forming monolayers on various surfaces. The surfaces can be selected from a wide array of materials, including, for example, aluminum dioxide, silicon dioxide, carbon and SiC. The substrates can be planar or porous. The monolayer is formed under enhanced pressure conditions. The monolayer contains functionalized molecules, and accordingly functionalizes a surface of the substrate. The properties of the functionalized substrate can enhance the substrate's applicability for numerous purposes including, for example, utilization in extracting contaminants, or incorporation into a polymeric matrix.

Methods of making monolayers

DOEpatents

Alford, Kentin L [Pasco, WA; Simmons, Kevin L [Kennewick, WA; Samuels, William D [Richland, WA; Zemanian, Thomas S [Richland, WA; Liu, Jun [Albuquerque, NM; Shin, Yongsoon [Richland, WA; Fryxell, Glen E [Kennewick, WA

2009-09-15

The invention pertains to methods of forming monolayers on various surfaces. The surfaces can be selected from a wide array of materials, including, for example, aluminum dioxide, silicon dioxide, carbon and SiC. The substrates can be planar or porous. The monolayer is formed under enhanced pressure conditions. The monolayer contains functionalized molecules, and accordingly functionalizes a surface of the substrate. The properties of the functionalized substrate can enhance the substrate's applicability for numerous purposes including, for example, utilization in extracting contaminants, or incorporation into a polymeric matrix.

Superhydrophobic surfaces’ influence on streaming current based energy harvester

NASA Astrophysics Data System (ADS)

Fouché, Florent; Dargent, Thomas; Coffinier, Yannick; Treizebré, Anthony; Vlandas, Alexis; Senez, Vincent

2016-11-01

The purpose of this paper is to report the design, fabrication and characterization of silicon-based microfluidic channels with superhydrophobic walls for energy harvesting. We present the fabrication step of silicon based streaming current energy harvester and the nanostructuration of the microchannel walls. We characterize the superhydrophobic properties of the surface in a closed system. Our preliminary results on the electrical characterization of the device show a 43% increase of power harvested with our superhydrophobic surface compared to a planar hydrophobic surface.

Molecular beam epitaxial growth and structural characterization of ZnS on (001) GaAs

NASA Technical Reports Server (NTRS)

Benz, R. G., II; Huang, P. C.; Stock, S. R.; Summers, C. J.

1988-01-01

The effect of surface nucleation processes on the quality of ZnS layers grown on (001) GaAs substrates by molecular beam epitaxy is reported. Reflection high energy electron diffraction indicated that nucleation at high temperatures produced more planar surfaces than nucleation at low temperatures, but the crystalline quality as assessed by X-ray double crystal diffractometry is relatively independent of nucleation temperature. A critical factor in layer quality was the initial roughness of the GaAs surfaces.

a 2d Model of Ultrasonic Testing for Cracks Near a Nonplanar Surface

NASA Astrophysics Data System (ADS)

Westlund, Jonathan; Boström, Anders

2010-02-01

2D P-SV elastic wave scattering by a crack near a non-planar surface is investigated. The wave scattering problem is solved in the frequency domain using a combination of the boundary element method (BEM) for the back surface displacement and a Fourier series expansion of the crack opening displacement (COD). The model accounts for the action of the transmitting and receiving ultrasonic contact probes, and the time traces are obtained by applying an inverse temporal Fourier transform.

The Gibbs free energy of homogeneous nucleation: From atomistic nuclei to the planar limit.

PubMed

Cheng, Bingqing; Tribello, Gareth A; Ceriotti, Michele

2017-09-14

In this paper we discuss how the information contained in atomistic simulations of homogeneous nucleation should be used when fitting the parameters in macroscopic nucleation models. We show how the number of solid and liquid atoms in such simulations can be determined unambiguously by using a Gibbs dividing surface and how the free energy as a function of the number of solid atoms in the nucleus can thus be extracted. We then show that the parameters (the chemical potential, the interfacial free energy, and a Tolman correction) of a model based on classical nucleation theory can be fitted using the information contained in these free-energy profiles but that the parameters in such models are highly correlated. This correlation is unfortunate as it ensures that small errors in the computed free energy surface can give rise to large errors in the extrapolated properties of the fitted model. To resolve this problem we thus propose a method for fitting macroscopic nucleation models that uses simulations of planar interfaces and simulations of three-dimensional nuclei in tandem. We show that when the chemical potentials and the interface energy are pinned to their planar-interface values, more precise estimates for the Tolman length are obtained. Extrapolating the free energy profile obtained from small simulation boxes to larger nuclei is thus more reliable.

Graphene as a transparent conducting and surface field layer in planar Si solar cells

PubMed Central

2014-01-01

This work presents an experimental and finite difference time domain (FDTD) simulation-based study on the application of graphene as a transparent conducting layer on a planar and untextured crystalline p-n silicon solar cell. A high-quality monolayer graphene with 97% transparency and 350 Ω/□ sheet resistance grown by atmospheric pressure chemical vapor deposition method was transferred onto planar Si cells. An increase in efficiency from 5.38% to 7.85% was observed upon deposition of graphene onto Si cells, which further increases to 8.94% upon SiO2 deposition onto the graphene/Si structure. A large increase in photon conversion efficiency as a result of graphene deposition shows that the electronic interaction and the presence of an electric field at the graphene/Si interface together play an important role in this improvement and additionally lead to a reduction in series resistance due to the conducting nature of graphene. PMID:25114642

A reusable evanescent wave immunosensor for highly sensitive detection of bisphenol A in water samples

NASA Astrophysics Data System (ADS)

Xiao-Hong, Zhou; Lan-Hua, Liu; Wei-Qi, Xu; Bao-Dong, Song; Jian-Wu, Sheng; Miao, He; Han-Chang, Shi

2014-04-01

This paper proposed a compact and portable planar waveguide evanescent wave immunosensor (EWI) for highly sensitive detection of BPA. The incident light is coupled into the planar waveguide chip via a beveled angle through undergoing total internal reflection, where the evanescent wave field forms and excites the binding fluorophore-tagged antibodies on the chip surface. Typical calibration curves obtained for BPA has detection limits of 0.03 μg/L. Linear response for BPA ranged from 0.124 μg/L-9.60 μg/L with 50% inhibition concentration for BPA of 1.09 +/- 0.25 μg/L. The regeneration of the planar optical waveguide chip allows the performance of more than 300 assay cycles within an analysis time of about 20 min for each assay cycle. By application of effective pretreatment procedure, the recoveries of BPA in real water samples gave values from 88.3% +/- 8.5% to 103.7% +/- 3.5%, confirming its application potential in the measurement of BPA in reality.

Interactive object modelling based on piecewise planar surface patches.

PubMed

Prankl, Johann; Zillich, Michael; Vincze, Markus

2013-06-01

Detecting elements such as planes in 3D is essential to describe objects for applications such as robotics and augmented reality. While plane estimation is well studied, table-top scenes exhibit a large number of planes and methods often lock onto a dominant plane or do not estimate 3D object structure but only homographies of individual planes. In this paper we introduce MDL to the problem of incrementally detecting multiple planar patches in a scene using tracked interest points in image sequences. Planar patches are reconstructed and stored in a keyframe-based graph structure. In case different motions occur, separate object hypotheses are modelled from currently visible patches and patches seen in previous frames. We evaluate our approach on a standard data set published by the Visual Geometry Group at the University of Oxford [24] and on our own data set containing table-top scenes. Results indicate that our approach significantly improves over the state-of-the-art algorithms.

Vertically Aligned Niobium Nanowire Arrays for Fast-Charging Micro-Supercapacitors.

PubMed

Mirvakili, Seyed M; Hunter, Ian W

2017-07-01

Planar micro-supercapacitors are attractive for system on chip technologies and surface mount devices due to their large areal capacitance and energy/power density compared to the traditional oxide-based capacitors. In the present work, a novel material, niobium nanowires, in form of vertically aligned electrodes for application in high performance planar micro-supercapacitors is introduced. Specific capacitance of up to 1 kF m -2 (100 mF cm -2 ) with peak energy and power density of 2 kJ m -2 (6.2 MJ m -3 or 1.7 mWh cm -3 ) and 150 kW m -2 (480 MW m -3 or 480 W cm -3 ), respectively, is achieved. This remarkable power density, originating from the extremely low equivalent series resistance value of 0.27 Ω (2.49 µΩ m 2 or 24.9 mΩ cm 2 ) and large specific capacitance, is among the highest for planar micro-supercapacitors electrodes made of nanomaterials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Room-temperature processed tin oxide thin film as effective hole blocking layer for planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Tao, Hong; Ma, Zhibin; Yang, Guang; Wang, Haoning; Long, Hao; Zhao, Hongyang; Qin, Pingli; Fang, Guojia

2018-03-01

Tin oxide (SnO2) film with high mobility and good transmittance has been reported as a promising semiconductor material for high performance perovskite solar cells (PSCs). In this study, ultrathin SnO2 film synthesized by radio frequency magnetron sputtering (RFMS) method at room temperature was employed as hole blocking layer for planar PSCs. The room-temperature sputtered SnO2 film not only shows favourable energy band structure but also improves the surface topography of fluorine doped SnO2 (FTO) substrate and perovskite (CH3NH3PbI3) layer. Thus, this SnO2 hole blocking layer can efficiently promote electron transport and suppress carrier recombination. Furthermore, the best efficiency of 13.68% was obtained for planar PSC with SnO2 hole blocking layer prepared at room temperature. This research highlights the room-temperature preparation process of hole blocking layer in PSC and has a certain reference significance for the usage of flexible and low-cost substrates.

Monomer volume fraction profiles in pH responsive planar polyelectrolyte brushes

DOE PAGES

Mahalik, Jyoti P.; Yang, Yubo; Deodhar, Chaitra V.; ...

2016-03-06

Spatial dependencies of monomer volume fraction profiles of pH responsive polyelectrolyte brushes were investigated using field theories and neutron reflectivity experiments. In particular, planar polyelectrolyte brushes in good solvent were studied and direct comparisons between predictions of the theories and experimental measurements are presented. The comparisons between the theories and the experimental data reveal that solvent entropy and ion-pairs resulting from adsorption of counterions from the added salt play key roles in affecting the monomer distribution and must be taken into account in modeling polyelectrolyte brushes. Furthermore, the utility of this physics-based approach based on these theories for the predictionmore » and interpretation of neutron reflectivity profiles in the context of pH responsive planar polyelectrolyte brushes such as polybasic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and polyacidic poly(methacrylic acid) (PMAA) brushes is demonstrated. The approach provides a quantitative way of estimating molecular weights of the polymers polymerized using surface-initiated atom transfer radical polymerization.« less

New Convex and Spherical Structures of Bare Boron Clusters

NASA Astrophysics Data System (ADS)

Boustani, Ihsan

1997-10-01

New stable structures of bare boron clusters can easily be obtained and constructed with the help of an "Aufbau Principle" suggested by a systematicab initioHF-SCF and direct CI study. It is concluded that boron cluster formation can be established by elemental units of pentagonal and hexagonal pyramids. New convex and small spherical clusters different from the classical known forms of boron crystal structures are obtained by a combination of both basic units. Convex structures simulate boron surfaces which can be considered as segments of open or closed spheres. Both convex clusters B16and B46have energies close to those of their conjugate quasi-planar clusters, which are relatively stable and can be considered to act as a calibration mark. The closed spherical clusters B12, B22, B32, and B42are less stable than the corresponding conjugated quasi-planar structures. As a consequence, highly stable spherical boron clusters can systematically be predicted when their conjugate quasi-planar clusters are determined and energies are compared.

Interactive object modelling based on piecewise planar surface patches☆

PubMed Central

Prankl, Johann; Zillich, Michael; Vincze, Markus

2013-01-01

Detecting elements such as planes in 3D is essential to describe objects for applications such as robotics and augmented reality. While plane estimation is well studied, table-top scenes exhibit a large number of planes and methods often lock onto a dominant plane or do not estimate 3D object structure but only homographies of individual planes. In this paper we introduce MDL to the problem of incrementally detecting multiple planar patches in a scene using tracked interest points in image sequences. Planar patches are reconstructed and stored in a keyframe-based graph structure. In case different motions occur, separate object hypotheses are modelled from currently visible patches and patches seen in previous frames. We evaluate our approach on a standard data set published by the Visual Geometry Group at the University of Oxford [24] and on our own data set containing table-top scenes. Results indicate that our approach significantly improves over the state-of-the-art algorithms. PMID:24511219

Electrochemical studies of Copper, Tantalum and Tantalum Nitride surfaces in aqueous solutions for applications in chemical-mechanical and electrochemical-mechanical planarization

NASA Astrophysics Data System (ADS)

Sulyma, Christopher Michael

This report will investigate fundamental properties of materials involved in integrated circuit (IC) manufacturing. Individual materials (one at a time) are studied in different electrochemical environmental solutions to better understand the kinetics associated with the polishing process. Each system tries to simulate a real CMP environment in order to compare our findings with what is currently used in industry. To accomplish this, a variety of techniques are used. The voltage pulse modulation technique is useful for electrochemical processing of metal and alloy surfaces by utilizing faradaic reactions like electrodeposition and electrodissolution. A theoretical framework is presented in chapter 4 to facilitate quantitative analysis of experimental data (current transients) obtained in this approach. A typical application of this analysis is demonstrated for an experimental system involving electrochemical removal of copper surface layers, a relatively new process for abrasive-free electrochemical mechanical planarization of copper lines used in the fabrication of integrated circuits. Voltage pulse modulated electrodissolution of Cu in the absence of mechanical polishing is activated in an acidic solution of oxalic acid and hydrogen peroxide. The current generated by each applied voltage step shows a sharp spike, followed by a double-exponential decay, and eventually attains the rectangular shape of the potential pulses. For the second system in chapter 5, open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu lines and Ta barriers in the fabrication of semiconductor devices. It is shown that in non-alkaline solutions of H2O2, the SA-promoted surface complexes of Cu and Ta can potentially support chemically enhanced material removal in low-pressure CMP of surface topographies overlying fragile low-k dielectrics. ADS can suppress Cu dissolution without significantly affecting the surface chemistry of Ta. Chapter 6 discusses anodic corrosion of Ta, which is examined as a possible route to voltage induced removal of Ta for potential applications in electrochemical mechanical planarization (ECMP) of diffusion barriers. This strategy involves electro-oxidation of Ta in the presence of NO3- anions to form mechanically weak surface oxide films, followed by removal of the oxide layers by moderate mechanical abrasion. This NO3 - system is compared with a reference solution of Br -. In both electrolytes, the voltammetric currents of anodic oxidation exhibit oscillatory behaviors in the initial cycles of slow (5 mV s-1) voltage scans. The frequencies of these current oscillations are show signature attributes of localized pitting or general surface corrosion caused by Br- or NO3 -, respectively. Scanning electron microscopy, cyclic voltammetry, polarization resistance measurements, and time resolved Fourier transform impedance spectroscopy provide additional details about these corrosion mechanism. Apart from their relevance in the context of ECMP, the results also address certain fundamental aspects of pitting and general corrosions. The general protocols necessary to combine and analyze the results of D.C. and A.C. electrochemical measurements involving such valve metal corrosion systems are discussed in detail. In chapter 7 potassium salts of certain oxyanions (nitrate, sulfate and phosphate in particular) are shown to serve as effective surface-modifying agents in chemically enhanced, low-pressure chemical mechanical planarization (CMP) of Ta and TaN barrier layers for interconnect structures. The surface reactions that form the basis of this CMP strategy are investigated here in detail using the electrochemical techniques of cyclic voltammetry, open circuit potential analysis, polarization resistance measurements, and Fourier transform impedance spectroscopy. The results suggest that forming structurally weak oxide layers on the CMP samples is a key to achieving the goal of chemically controlled CMP of Ta/TaN at low down-pressures. (Abstract shortened by UMI.)

Harvesting water wave energy by asymmetric screening of electrostatic charges on a nanostructured hydrophobic thin-film surface.

PubMed

Zhu, Guang; Su, Yuanjie; Bai, Peng; Chen, Jun; Jing, Qingshen; Yang, Weiqing; Wang, Zhong Lin

2014-06-24

Energy harvesting from ambient water motions is a desirable but underexplored solution to on-site energy demand for self-powered electronics. Here we report a liquid-solid electrification-enabled generator based on a fluorinated ethylene propylene thin film, below which an array of electrodes are fabricated. The surface of the thin film is charged first due to the water-solid contact electrification. Aligned nanowires created on the thin film make it hydrophobic and also increase the surface area. Then the asymmetric screening to the surface charges by the waving water during emerging and submerging processes causes the free electrons on the electrodes to flow through an external load, resulting in power generation. The generator produces sufficient output power for driving an array of small electronics during direct interaction with water bodies, including surface waves and falling drops. Polymer-nanowire-based surface modification increases the contact area at the liquid-solid interface, leading to enhanced surface charging density and thus electric output at an efficiency of 7.7%. Our planar-structured generator features an all-in-one design without separate and movable components for capturing and transmitting mechanical energy. It has extremely lightweight and small volume, making it a portable, flexible, and convenient power solution that can be applied on the ocean/river surface, at coastal/offshore areas, and even in rainy places. Considering the demonstrated scalability, it can also be possibly used in large-scale energy generation if layers of planar sheets are connected into a network.

Smectic C chevrons in nanocylinders

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

Lefort, R., E-mail: ronan.lefort@univ-rennes1.fr; Morineau, D.; Jean, F.

2014-11-17

The structure of an achiral smectic-C liquid crystal confined in nanocylinders with a planar surface anchoring is studied by small angle neutron scattering. We observe an invariant alignment of the nematic director with the pore axis, that promotes an original chevron structure with revolution symmetry.

ToF-SIMS measurements with topographic information in combined images.

PubMed

Koch, Sabrina; Ziegler, Georg; Hutter, Herbert

2013-09-01

In 2D and 3D time-of-flight secondary ion mass spectrometric (ToF-SIMS) analysis, accentuated structures on the sample surface induce distorted element distributions in the measurement. The origin of this effect is the 45° incidence angle of the analysis beam, recording planar images with distortion of the sample surface. For the generation of correct element distributions, these artifacts associated with the sample surface need to be eliminated by measuring the sample surface topography and applying suitable algorithms. For this purpose, the next generation of ToF-SIMS instruments will feature a scanning probe microscope directly implemented in the sample chamber which allows the performance of topography measurements in situ. This work presents the combination of 2D and 3D ToF-SIMS analysis with topographic measurements by ex situ techniques such as atomic force microscopy (AFM), confocal microscopy (CM), and digital holographic microscopy (DHM). The concept of the combination of topographic and ToF-SIMS measurements in a single representation was applied to organic and inorganic samples featuring surface structures in the nanometer and micrometer ranges. The correct representation of planar and distorted ToF-SIMS images was achieved by the combination of topographic data with images of 2D as well as 3D ToF-SIMS measurements, using either AFM, CM, or DHM for the recording of topographic data.

Microstructure and magnetism of Co2FeAl Heusler alloy prepared by arc and induction melting compared with planar flow casting

NASA Astrophysics Data System (ADS)

Titov, A.; Jiraskova, Y.; Zivotsky, O.; Bursik, J.; Janickovic, D.

2018-04-01

This paper is devoted to investigations of the structural and magnetic properties of the Co2FeAl Heusler alloy produced by three technologies. The alloys prepared by arc and induction melting have resulted in coarse-grained samples in contrast to the fine-grained ribbon-type sample prepared by planar flow casting. Scanning electron microscopy completed by energy dispersive X-ray spectroscopy, X-ray diffraction, Mössbauer spectroscopy, and magnetic methods sensitive to both bulk and surface were applied. The chemical composition was slightly different from the nominal only for the ribbon sample. From the viewpoint of magnetic properties, the bulk coercivity and remnant magnetization have followed the structure influenced by the technology used. Saturation magnetization was practically the same for samples prepared by arc and induction melting, whereas the magnetization of ribbon is slightly lower due to a higher Al content at the expense of iron and cobalt. The surface magnetic properties were markedly influenced by anisotropy, grain size, and surface roughness of the samples. The surface roughness and brittleness of the ribbon-type sample did not make domain structure observation possible. The other two samples could be well polished and their highly smooth surface has enabled domain structure visualization by both magneto-optical Kerr microscopy and magnetic force microscopy.

Constrained surface controllers for three-dimensional image data reformatting.

PubMed

Graves, Martin J; Black, Richard T; Lomas, David J

2009-07-01

This study did not require ethical approval in the United Kingdom. The aim of this work was to create two controllers for navigating a two-dimensional image plane through a volumetric data set, providing two important features of the ultrasonographic paradigm: orientation matching of the navigation device and the desired image plane in the three-dimensional (3D) data and a constraining surface to provide a nonvisual reference for the image plane location in the 3D data. The first constrained surface controller (CSC) uses a planar constraining surface, while the second CSC uses a hemispheric constraining surface. Ten radiologists were asked to obtain specific image reformations by using both controllers and a commercially available medical imaging workstation. The time taken to perform each reformatting task was recorded. The users were also asked structured questions comparing the utility of both methods. There was a significant reduction in the time taken to perform the specified reformatting tasks by using the simpler planar controller as compared with a standard workstation, whereas there was no significant difference for the more complex hemispheric controller. The majority of users reported that both controllers allowed them to concentrate entirely on the reformatting task and the related image rather than being distracted by the need for interaction with the workstation interface. In conclusion, the CSCs provide an intuitive paradigm for interactive reformatting of volumetric data. (c) RSNA, 2009.

Analytical and Photogrammetric Characterization of a Planar Tetrahedral Truss

NASA Technical Reports Server (NTRS)

Wu, K. Chauncey; Adams, Richard R.; Rhodes, Marvin D.

1990-01-01

Future space science missions are likely to require near-optical quality reflectors which are supported by a stiff truss structure. This support truss should conform closely with its intended shape to minimize its contribution to the overall surface error of the reflector. The current investigation was conducted to evaluate the planar surface accuracy of a regular tetrahedral truss structure by comparing the results of predicted and measured node locations. The truss is a 2-ring hexagonal structure composed of 102 equal-length truss members. Each truss member is nominally 2 meters in length between node centers and is comprised of a graphite/epoxy tube with aluminum nodes and joints. The axial stiffness and the length variation of the truss components were determined experimentally and incorporated into a static finite element analysis of the truss. From this analysis, the root mean square (RMS) surface error of the truss was predicted to be 0.11 mm (0004 in). Photogrammetry tests were performed on the assembled truss to measure the normal displacements of the upper surface nodes and to determine if the truss would maintain its intended shape when subjected to repeated assembly. Considering the variation in the truss component lengths, the measures rms error of 0.14 mm (0.006 in) in the assembled truss is relatively small. The test results also indicate that a repeatable truss surface is achievable. Several potential sources of error were identified and discussed.

An efficient copper phthalocyanine additive of perovskite precursor for improving the photovoltaic performance of planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Wu, Shufang; Liu, Qingwei; Zheng, Ya; Li, Renjie; Peng, Tianyou

2017-08-01

Solution processable planar heterojunction perovskite solar cell has drawn much attention as a promising low-cost photovoltaic device, and much effort has been made to improve its power conversion efficiency by choosing appropriate additives for the perovskite precursor solution. Different to those additives reported, a soluble and thermal stable tert-butyl substituted copper phthalocyanine (CuPc(tBu)4) as additive is first introduced into the perovskite precursor solution of a planar perovskite solar cell that is fabricated via the one-step solution process. It is found that the pristine device without CuPc(tBu)4 additive exhibits a power conversion efficiency of 15.3%, while an extremely low concentration (4.4 × 10-3 mM) of CuPc(tBu)4 in the precursor solution leads to the corresponding device achieving an enhanced power conversion efficiency of 17.3%. CuPc(tBu)4 as an additive can improve the quality of perovskite layer with higher crystallinity and surface coverage, then resulting in enhanced light absorption and reduced charge recombination, and thus the better power conversion efficiency. The finding presented here provides a new choice for improving the quality of perovskite layer and the photovoltaic performance of the planar heterojunction perovskite solar cells.

Role of molecular conformations in rubrene polycrystalline films growth from vacuum deposition at various substrate temperatures

NASA Astrophysics Data System (ADS)

Lin, Ku-Yen; Wang, Yan-Jun; Chen, Ko-Lun; Ho, Ching-Yuan; Yang, Chun-Chuen; Shen, Ji-Lin; Chiu, Kuan-Cheng

2017-01-01

We report on the optical and structural characterization of rubrene polycrystalline films fabricated from vacuum deposition with various substrate temperatures (Tsub). Depending on Tsub, the role of twisted and planar rubrene conformational isomers on the properties of rubrene films is focused. The temperature (T)-dependent inverse optical transmission (IOT) and photoluminescence (PL) spectra were performed on these rubrene films. The origins of these IOT and PL peaks are explained in terms of the features from twisted and planar rubrene molecules and of the band characteristics from rubrene molecular solid films. Here, two rarely reported weak-peaks at 2.431 and 2.605 eV were observed from IOT spectra, which are associated with planar rubrene. Besides, the T-dependence of optical bandgap deduced from IOT spectra is discussed with respect to Tsub. Together with IOT and PL spectra, for Tsub > 170 °C, the changes in surface morphology and unit cell volume were observed for the first time, and are attributed to the isomeric transformation from twisted to planar rubrenes during the deposition processes. Furthermore, a unified schematic diagram in terms of Frenkel exciton recombination is suggested to explain the origins of the dominant PL peaks performed on these rubrene films at 15 K.

Planar air-bearing microgravity simulators: Review of applications, existing solutions and design parameters

NASA Astrophysics Data System (ADS)

Rybus, Tomasz; Seweryn, Karol

2016-03-01

All devices designed to be used in space must be thoroughly tested in relevant conditions. For several classes of devices the reduced gravity conditions are the key factor. In early stages of development and later due to financial reasons, the tests need to be done on Earth. However, in Earth conditions it is impossible to obtain a different gravity field independent on all linear and rotational spatial coordinates. Therefore, various test-bed systems are used, with their design driven by the device's specific needs. One of such test-beds are planar air-bearing microgravity simulators. In such an approach, the tested objects (e.g., manipulators intended for on-orbit operations or vehicles simulating satellites in a close formation flight) are mounted on planar air-bearings that allow almost frictionless motion on a flat surface, thus simulating microgravity conditions in two dimensions. In this paper we present a comprehensive review of research activities related to planar air-bearing microgravity simulators, demonstrating achievements of the most active research groups and describing newest trends and ideas, such as tests of landing gears for low-g bodies. Major design parameters of air-bearing test-beds are also reviewed and a list of notable existing test-beds is presented.

Solid-state structure of 1-(diaminomethylene)thiouron-1-ium propionate

NASA Astrophysics Data System (ADS)

Janczak, Jan

2017-10-01

The single crystals of 1-(diaminomethylene)thiouron-1-ium propionate suitable for the X-ray analysis were grown using a solution growth technique room temperature. The compound crystallises in the centrosymmetric C2/c space group of the monoclinic system. The conformation of the 1-(diaminomethylene)thiouron-1-ium cation is not strictly planar, but slightly twisted. Both planar arms of the cation are oppositely rotated by 2.1(1)° around the Csbnd N bonds involving the central N atom. The propionate(-) anion is also non-planar, the carboxylate group is turned by 4.3(1)° in relation to the planar carbon chain. The arrangement of oppositely charged components, i.e. 1-(diaminomethylene)thiouron-1-ium cations and propionate(-) anions in the crystal is mainly determined by ionic and Nsbnd H⋯O hydrogen bonding interactions forming two-dimensional network aligned to (100) plane. The neighbouring 2D layers interact via much weaker Nsbnd H⋯S hydrogen bonds forming three-dimensional hydrogen bonded network. Hirshfeld surface and the analysis of 2D fingerprint plots are illustrating both quantitatively and qualitatively interactions governing the supramolecular assemblies. The compound was also characterised by the FT-IR and Raman spectroscopy. The vibrational assignments have been supported by the isotopic frequency shift.

Method and device for ion mobility separations

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

Ibrahim, Yehia M.; Garimella, Sandilya V. B.; Smith, Richard D.

2017-07-11

Methods and devices for ion separations or manipulations in gas phase are disclosed. The device includes a single non-planar surface. Arrays of electrodes are coupled to the surface. A combination of RF and DC voltages are applied to the arrays of electrodes to create confining and driving fields that move ions through the device. The DC voltages are static DC voltages or time-dependent DC potentials or waveforms.

A Large-Surface-Area Boracite-Network-Topology Porous MOF Constructed from a Conjugated Ligand Exhibiting a High Hydrogen Uptake Capacity

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

Wang, Xi-Sen; Ma, Shengqian; Yuan, Daqiang

2009-01-01

A new porous metal-organic framework, PCN-20 with a twisted boracite net topology, was constructed based on a highly conjugated planar tricarboxylate ligand; PCN-20 possesses a large Langmuir surface area of over 4200 m(2)/g as well as demonstrates a high hydrogen uptake capacity of 6.2 wt % at 77 K and 50 bar.

Brownian dynamics simulations of simplified cytochrome c molecules in the presence of a charged surface

NASA Astrophysics Data System (ADS)

Gorba, C.; Geyer, T.; Helms, V.

2004-07-01

Simulations were performed for up to 150 simplified spherical horse heart cytochrome c molecules in the presence of a charged surface, which serves as an approximate model for a lipid membrane. Screened electrostatic and short-ranged attractive as well as repulsive van der Waals forces for interparticle and particle-membrane interactions are utilized in the simulations. At a distance from the membrane, where particle-membrane interactions are negligible, the simulation is coupled to a noninteraction continuum analogous to a heat bath [Geyer et al., J. Chem. Phys. 120, 4573 (2004)]. From the particles' density profiles perpendicular to the planar surface binding isotherms are derived and compared to experimental results [Heimburg et al. (1999)]. Using a negatively charged structureless membrane surface a saturation effect was found for relatively large particle concentrations. Since biological membranes often contain membrane proteins, we also studied the influence of additional charges on our model membrane mimicking bacterial reaction centers. We find that the onset of the saturation occurs for much lower concentrations and is sensitive to the detailed implementation. Therefore we suggest that local distortion of membrane planarity (undulation), or lipid demixing, or the presence of charged integral membrane proteins create preferential binding sites on the membrane. Only then do we observe saturation at physiological concentrations.

Kinetic theory of heterogeneous nucleation; effect of nonuniform density in the nuclei.

PubMed

Berim, Gersh O; Ruckenstein, Eli

2011-03-01

The heterogeneous nucleation of a liquid from a vapor in contact with a planar solid surface or a solid surface with cavities is examined on the basis of the kinetic theory of nucleation developed by Nowakowski and Ruckenstein [J. Phys. Chem. 96 (1992) 2313] which is extended to nonuniform fluid density distribution (FDD) in the nucleus. The latter is determined under the assumption that at each moment the FDD in the nucleus is provided by the density functional theory (DFT) for a nanodrop. As a result of this assumption, the theory does not require to consider that the contact angle which the nucleus makes with the solid surface and the density of the nucleus are independent parameters since they are provided by the DFT. For all considered cases, the nucleation rate is higher in the cavities than on a planar surface and increases with increasing strength of the fluid-solid interactions and decreasing cavity radius. The difference is small at high supersaturations (small critical nuclei), but becomes larger at low supersaturations when the critical nucleus has a size comparable with the size of the cavity. The nonuniformity of the FDD in the nucleus decreases the nucleation rate when compared to the uniform FDD. Copyright © 2010 Elsevier Inc. All rights reserved.

Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

NASA Astrophysics Data System (ADS)

Pettit, J. R.; Walker, A. E.; Lowe, M. J. S.

2015-03-01

Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) method has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.

The Poisson-Helmholtz-Boltzmann model.

PubMed

Bohinc, K; Shrestha, A; May, S

2011-10-01

We present a mean-field model of a one-component electrolyte solution where the mobile ions interact not only via Coulomb interactions but also through a repulsive non-electrostatic Yukawa potential. Our choice of the Yukawa potential represents a simple model for solvent-mediated interactions between ions. We employ a local formulation of the mean-field free energy through the use of two auxiliary potentials, an electrostatic and a non-electrostatic potential. Functional minimization of the mean-field free energy leads to two coupled local differential equations, the Poisson-Boltzmann equation and the Helmholtz-Boltzmann equation. Their boundary conditions account for the sources of both the electrostatic and non-electrostatic interactions on the surface of all macroions that reside in the solution. We analyze a specific example, two like-charged planar surfaces with their mobile counterions forming the electrolyte solution. For this system we calculate the pressure between the two surfaces, and we analyze its dependence on the strength of the Yukawa potential and on the non-electrostatic interactions of the mobile ions with the planar macroion surfaces. In addition, we demonstrate that our mean-field model is consistent with the contact theorem, and we outline its generalization to arbitrary interaction potentials through the use of a Laplace transformation. © EDP Sciences / Società Italiana di Fisica / Springer-Verlag 2011

A support-operator method for 3-D rupture dynamics

NASA Astrophysics Data System (ADS)

Ely, Geoffrey P.; Day, Steven M.; Minster, Jean-Bernard

2009-06-01

We present a numerical method to simulate spontaneous shear crack propagation within a heterogeneous, 3-D, viscoelastic medium. Wave motions are computed on a logically rectangular hexahedral mesh, using the generalized finite-difference method of Support Operators (SOM). This approach enables modelling of non-planar surfaces and non-planar fault ruptures. Our implementation, the Support Operator Rupture Dynamics (SORD) code, is highly scalable, enabling large-scale, multiprocessors calculations. The fault surface is modelled by coupled double nodes, where rupture occurs as dictated by the local stress conditions and a frictional failure law. The method successfully performs test problems developed for the Southern California Earthquake Center (SCEC)/U.S. Geological Survey (USGS) dynamic earthquake rupture code validation exercise, showing good agreement with semi-analytical boundary integral method results. We undertake further dynamic rupture tests to quantify numerical errors introduced by shear deformations to the hexahedral mesh. We generate a family of meshes distorted by simple shearing, in the along-strike direction, up to a maximum of 73°. For SCEC/USGS validation problem number 3, grid-induced errors increase with mesh shear angle, with the logarithm of error approximately proportional to angle over the range tested. At 73°, rms misfits are about 10 per cent for peak slip rate, and 0.5 per cent for both rupture time and total slip, indicating that the method (which, up to now, we have applied mainly to near-vertical strike-slip faulting) is also capable of handling geometries appropriate to low-angle surface-rupturing thrust earthquakes. Additionally, we demonstrate non-planar rupture effects, by modifying the test geometry to include, respectively, cylindrical curvature and sharp kinks.

Solution-Processed hybrid Sb2 S3 planar heterojunction solar cell

NASA Astrophysics Data System (ADS)

Huang, Wenxiao; Borazan, Ismail; Carroll, David

Thin-film solar cells based on inorganic absorbers permit a high efficiency and stability. Among or those absorber candidates, recently Sb2S3 has attracted extensive attention because of its suitable band gap (1.5eV ~1.7 eV) , strong optical absorption, low-cost and earth-abundant constituents. Currently high-efficiency Sb2S3 solar cells have absorber layer deposited on nanostructured TiO2 electrodes in combination with organic hole transport material (HTM) on top. However it's challenging to fill the nanostructured TiO2 layer with Sb2S3 and subsequently by HTM, this leads to uncovered surface permits charge recombination. And the existing of Sb2S3/TiO2/HTM triple interface will enhance the recombination due to the surface trap state. Therefore, a planar junction cell would not only have simpler structure with less steps to fabricate but also ideally also have a higher open circuit voltage because of less interface carrier recombination. By far there is limited research focusing on planar Sb2S3 solar cell, so the feasibility is still unclear. Here, we developed a low-toxic solution method to fabricate Sb2S3 thin film solar cell, then we studied the morphology of the Sb2S3 layer and its impact to the device performance. The best device with a structure of FTO/TiO2/Sb2S3/P3HT/Ag has PCE over 5% which is similar or higher than yet the best nanostructure devices with the same HTM. Furthermore, based on solution engineering and surface modification, we improved the Sb2S3 film quality and achieved a record PCE. .

Object recognition and pose estimation of planar objects from range data

NASA Technical Reports Server (NTRS)

Pendleton, Thomas W.; Chien, Chiun Hong; Littlefield, Mark L.; Magee, Michael

1994-01-01

The Extravehicular Activity Helper/Retriever (EVAHR) is a robotic device currently under development at the NASA Johnson Space Center that is designed to fetch objects or to assist in retrieving an astronaut who may have become inadvertently de-tethered. The EVAHR will be required to exhibit a high degree of intelligent autonomous operation and will base much of its reasoning upon information obtained from one or more three-dimensional sensors that it will carry and control. At the highest level of visual cognition and reasoning, the EVAHR will be required to detect objects, recognize them, and estimate their spatial orientation and location. The recognition phase and estimation of spatial pose will depend on the ability of the vision system to reliably extract geometric features of the objects such as whether the surface topologies observed are planar or curved and the spatial relationships between the component surfaces. In order to achieve these tasks, three-dimensional sensing of the operational environment and objects in the environment will therefore be essential. One of the sensors being considered to provide image data for object recognition and pose estimation is a phase-shift laser scanner. The characteristics of the data provided by this scanner have been studied and algorithms have been developed for segmenting range images into planar surfaces, extracting basic features such as surface area, and recognizing the object based on the characteristics of extracted features. Also, an approach has been developed for estimating the spatial orientation and location of the recognized object based on orientations of extracted planes and their intersection points. This paper presents some of the algorithms that have been developed for the purpose of recognizing and estimating the pose of objects as viewed by the laser scanner, and characterizes the desirability and utility of these algorithms within the context of the scanner itself, considering data quality and noise.

SU-F-T-301: Planar Dose Pass Rate Inflation Due to the MapCHECK Measurement Uncertainty Function

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

Bailey, D; Spaans, J; Kumaraswamy, L

Purpose: To quantify the effect of the Measurement Uncertainty function on planar dosimetry pass rates, as analyzed with Sun Nuclear Corporation analytic software (“MapCHECK” or “SNC Patient”). This optional function is toggled on by default upon software installation, and automatically increases the user-defined dose percent difference (%Diff) tolerance for each planar dose comparison. Methods: Dose planes from 109 IMRT fields and 40 VMAT arcs were measured with the MapCHECK 2 diode array, and compared to calculated planes from a commercial treatment planning system. Pass rates were calculated within the SNC analytic software using varying calculation parameters, including Measurement Uncertainty onmore » and off. By varying the %Diff criterion for each dose comparison performed with Measurement Uncertainty turned off, an effective %Diff criterion was defined for each field/arc corresponding to the pass rate achieved with MapCHECK Uncertainty turned on. Results: For 3%/3mm analysis, the Measurement Uncertainty function increases the user-defined %Diff by 0.8–1.1% average, depending on plan type and calculation technique, for an average pass rate increase of 1.0–3.5% (maximum +8.7%). For 2%, 2 mm analysis, the Measurement Uncertainty function increases the user-defined %Diff by 0.7–1.2% average, for an average pass rate increase of 3.5–8.1% (maximum +14.2%). The largest increases in pass rate are generally seen with poorly-matched planar dose comparisons; the MapCHECK Uncertainty effect is markedly smaller as pass rates approach 100%. Conclusion: The Measurement Uncertainty function may substantially inflate planar dose comparison pass rates for typical IMRT and VMAT planes. The types of uncertainties incorporated into the function (and their associated quantitative estimates) as described in the software user’s manual may not accurately estimate realistic measurement uncertainty for the user’s measurement conditions. Pass rates listed in published reports or otherwise compared to the results of other users or vendors should clearly indicate whether the Measurement Uncertainty function is used.« less

Development of a wavelength tunable filter using MEMS technology

NASA Astrophysics Data System (ADS)

Liu, Junting

Microelectromechanical systems (MEMS) for optical applications have received intensive attention in recent years because of their potential applications in optical telecommunication. Traditional wavelength division multiplexing (WDM) offers high capacity but requires the fabrication of selective add-drop filters. MEMS technology offers an effective way to fabricate these components at low cost. This thesis presents the development of a device that tunes the Bragg wavelength by coupling into the evanescent field of the grating. A Bragg grating is a periodic perturbation of the refractive index along a fiber or a periodic perturbation of the structure of a planar waveguide. The Bragg wavelength can be tuned by changing the degree to which a dielectric slab couples into the evanescent field. The result is a change in the effective index of the grating, and thus a change in the wavelength that which it reflects. In this thesis Bragg gratings were successfully written into an optical fiber using phase mask technique. Mechanical polishing was used to side-polish the fiber and remove cladding to expose the core. Grating structures were also fabricated in planar waveguide using E-beam writing and dry etching. In order to achieve the smoothest possible morphology of the waveguide, plasma dry etching of transparent substrates was studied in great detail. It is found that the pre-etch cleaning procedure greatly influences the ability to obtain a smooth etched surface. Upper limits of evanescent field tuning were investigated by applying different index liquids such as D. I. water and index matching oils or by positioning different dielectric materials such as glass and silicon close to the grating. Planar waveguides were found to be more sensitive to effective index change. Two kinds of computer simulation were carried out to understand the mode profile and to estimate the value of effective index of planar waveguide under "dry" and "wet" conditions. The first one used an average depth of grating approximation. The second explicitly considered the corrugated structure of the waveguide. Results of both simulations were compared with the experimental results in order to find the proper simulation approach. The fiber or planar waveguide gratings were "device" integrated and their pro and cons were compared. Devices using an optical fiber employed a microactuator driven by electrothermal vibromotor to change the degree of coupling between fiber and "tuning block". Device using planar waveguides used an electrostatic force actuated membrane, flip-chip mounted atop the waveguide. All devices were fabricated using polysilicon surface micromachining processes. I concluded that devices driven by electrostatic force were easier to actuate and their integration with waveguide less challenging.

Suppression of laser nonuniformity imprinting using a thin high-z coating.

PubMed

Karasik, Max; Weaver, J L; Aglitskiy, Y; Oh, J; Obenschain, S P

2015-02-27

Imprinting of laser nonuniformity is a limiting factor in direct-drive inertial confinement fusion experiments, particularly when available laser smoothing is limited. A thin (∼400  Å) high-Z metal coating is found to substantially suppress laser imprint for planar targets driven by pulse shapes and intensities relevant to implosions on the National Ignition Facility while retaining low adiabat target acceleration. A hybrid of indirect and direct drive, this configuration results in initial ablation by x rays from the heated high-Z layer, creating a large standoff for perturbation smoothing.

Surface morphology evolution during plasma etching of silicon: roughening, smoothing and ripple formation

NASA Astrophysics Data System (ADS)

Ono, Kouichi; Nakazaki, Nobuya; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji

2017-10-01

Atomic- or nanometer-scale roughness on feature surfaces has become an important issue to be resolved in the fabrication of nanoscale devices in industry. Moreover, in some cases, smoothing of initially rough surfaces is required for planarization of film surfaces, and controlled surface roughening is required for maskless fabrication of organized nanostructures on surfaces. An understanding, under what conditions plasma etching results in surface roughening and/or smoothing and what are the mechanisms concerned, is of great technological as well as fundamental interest. In this article, we review recent developments in the experimental and numerical study of the formation and evolution of surface roughness (or surface morphology evolution such as roughening, smoothing, and ripple formation) during plasma etching of Si, with emphasis being placed on a deeper understanding of the mechanisms or plasma-surface interactions that are responsible for. Starting with an overview of the experimental and theoretical/numerical aspects concerned, selected relevant mechanisms are illustrated and discussed primarily on the basis of systematic/mechanistic studies of Si etching in Cl-based plasmas, including noise (or stochastic roughening), geometrical shadowing, surface reemission of etchants, micromasking by etch inhibitors, and ion scattering/chanelling. A comparison of experiments (etching and plasma diagnostics) and numerical simulations (Monte Carlo and classical molecular dynamics) indicates a crucial role of the ion scattering or reflection from microscopically roughened feature surfaces on incidence in the evolution of surface roughness (and ripples) during plasma etching; in effect, the smoothing/non-roughening condition is characterized by reduced effects of the ion reflection, and the roughening-smoothing transition results from reduced ion reflections caused by a change in the predominant ion flux due to that in plasma conditions. Smoothing of initially rough surfaces as well as non-roughening of initially planar surfaces during etching (normal ion incidence) and formation of surface ripples by plasma etching (off-normal ion incidence) are also presented and discussed in this context.

Characterizing a four-qubit planar lattice for arbitrary error detection

NASA Astrophysics Data System (ADS)

Chow, Jerry M.; Srinivasan, Srikanth J.; Magesan, Easwar; Córcoles, A. D.; Abraham, David W.; Gambetta, Jay M.; Steffen, Matthias

2015-05-01

Quantum error correction will be a necessary component towards realizing scalable quantum computers with physical qubits. Theoretically, it is possible to perform arbitrarily long computations if the error rate is below a threshold value. The two-dimensional surface code permits relatively high fault-tolerant thresholds at the ~1% level, and only requires a latticed network of qubits with nearest-neighbor interactions. Superconducting qubits have continued to steadily improve in coherence, gate, and readout fidelities, to become a leading candidate for implementation into larger quantum networks. Here we describe characterization experiments and calibration of a system of four superconducting qubits arranged in a planar lattice, amenable to the surface code. Insights into the particular qubit design and comparison between simulated parameters and experimentally determined parameters are given. Single- and two-qubit gate tune-up procedures are described and results for simultaneously benchmarking pairs of two-qubit gates are given. All controls are eventually used for an arbitrary error detection protocol described in separate work [Corcoles et al., Nature Communications, 6, 2015].

Infrared thermography for inspecting of pipeline specimen

NASA Astrophysics Data System (ADS)

Chen, Dapeng; Li, Xiaoli; Sun, Zuoming; Zhang, Xiaolong

2018-02-01

Infrared thermography is a fast and effective non-destructive testing method, which has an increasing application in the field of Aeronautics, Astronautic, architecture and medical, et al. Most of the reports about the application of this technology are focus on the specimens of planar, pulse light is often used as the heat stimulation and a plane heat source is generated on the surface of the specimen by the using of a lampshade, however, this method is not suitable for the specimen of non-planar, such as the pipeline. Therefore, in this paper, according the NDT problem of a steel and composite pipeline specimen, ultrasonic and hot water are applied as the heat source respectively, and an IR camera is used to record the temperature varies of the surface of the specimen, defects are revealed by the thermal images sequence processing. Furthermore, the results of light pulse thermography are also shown as comparison, it is indicated that choose the right stimulation method, can get a more effective NDT results for the pipeline specimen.

Precision Measurement of Phonon-Polaritonic Near-Field Energy Transfer between Macroscale Planar Structures Under Large Thermal Gradients

NASA Astrophysics Data System (ADS)

Ghashami, Mohammad; Geng, Hongyao; Kim, Taehoon; Iacopino, Nicholas; Cho, Sung Kwon; Park, Keunhan

2018-04-01

Despite its strong potentials in emerging energy applications, near-field thermal radiation between large planar structures has not been fully explored in experiments. Particularly, it is extremely challenging to control a subwavelength gap distance with good parallelism under large thermal gradients. This article reports the precision measurement of near-field radiative energy transfer between two macroscale single-crystalline quartz plates that support surface phonon polaritons. Our measurement scheme allows the precise control of a gap distance down to 200 nm in a highly reproducible manner for a surface area of 5 × 5 mm2 . We have measured near-field thermal radiation as a function of the gap distance for a broad range of thermal gradients up to ˜156 K , observing more than 40 times enhancement of thermal radiation compared to the blackbody limit. By comparing with theoretical prediction based on fluctuational electrodynamics, we demonstrate that such remarkable enhancement is owing to phonon-polaritonic energy transfer across a nanoscale vacuum gap.

RHEED oscillations in spinel ferrite epitaxial films grown by conventional planar magnetron sputtering

NASA Astrophysics Data System (ADS)

Ojima, T.; Tainosho, T.; Sharmin, S.; Yanagihara, H.

2018-04-01

Real-time in situ reflection high energy electron diffraction (RHEED) observations of Fe3O4, γ-Fe2O3, and (Co,Fe)3O4 films on MgO(001) substrates grown by a conventional planar magnetron sputtering was studied. The change in periodical intensity of the specular reflection spot in the RHEED images of three different spinel ferrite compounds grown by two different sputtering systems was examined. The oscillation period was found to correspond to the 1/4 unit cell of each spinel ferrite, similar to that observed in molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) experiments. This suggests that the layer-by-layer growth of spinel ferrite (001) films is general in most physical vapor deposition (PVD) processes. The surfaces of the films were as flat as the surface of the substrate, consistent with the observed layer-by-layer growth process. The observed RHEED oscillation indicates that even a conventional sputtering method can be used to control film thickness during atomic layer depositions.

Nanohelices from planar polymer self-assembled in carbon nanotubes

PubMed Central

Fu, Hongjin; Xu, Shuqiong; Li, Yunfang

2016-01-01

The polymer possessing with planar structure can be activated and guided to encapsulate the inner space of SWNT and form a helix through van der Waals interaction and the π-π stacking effect between the polymer and the inner surface of SWNT. The SWNT size, the nanostructure and flexibility of polymer chain are all determine the final structures. The basic interaction between the polymer and the nanotubes is investigated, and the condition and mechanism of the helix-forming are explained particularly. Hybrid polymers improve the ability of the helix formation. This study provides scientific basis for fabricating helical polymers encapsulated in SWNTs and eventually on their applications in various areas. PMID:27440493

Additives for high-temperature liquid lubricants

NASA Technical Reports Server (NTRS)

Lawton, Emil A.; Yavrouian, Andre H.; Repar, John

1988-01-01

A preliminary research program was conducted to demonstrate a new concept for additives to liquid lubricants. It was demonstrated that suspensions of o-phthalonitrile and a substituted 1,2-maleonitrile in mineral oil and dilute solutions of o-phthalonitrile and tetrafluoro-o-phthalonitrile extended the lifetime of bearings under boundary lubricating conditions. The solutions exhibited coefficients of friction under high loads of 0.02-0.03. These results were consistent with the hypothesis that these compounds react with the hot metal surface to form a planar lubricating film by means of a metal or metal oxide template reaction. Also, the adherence was very strong due to the chelating action of the planar macrocycles postulated to form under the experimental conditions.

Positioning growth of NPB crystalline nanowires on the PTCDA nanocrystal template.

PubMed

Wang, Hong; Lin, Haiping; Fan, Xing; Ostendorp, Stefan; Wang, Yandong; Huang, Lizhen; Jiang, Lin; Li, Youyong; Wilde, Gerhard; Fuchs, Harald; Wang, Wenchong; Chi, Lifeng

2018-05-31

Non-planar organic molecules often form amorphous films via vapor phase deposition on surfaces. In this study, we demonstrate for the first time that direct crystalline growth of non-planar NPB is possible when the orientation of initially deposited molecules on a PTCDA nanocrystal template is controlled to make it analogous to the structure of the molecular crystal. The crystalline NPB nanowires can be further positioned by controlling the site-selective growth of PTCDA nanocrystal templates at pre-determined locations. Short channel bottom contact OFET array with the NPB nanowires directly grown on electrodes were subsequently fabricated. The hole mobility of NPB nanowires is improved by 40-fold in comparison to that of the amorphous films.

A planar chiral meta-surface for optical vortex generation and focusing

PubMed Central

Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Wang, Yanqin; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Wang, Changtao; Zhao, ZeYu; Luo, Xiangang

2015-01-01

Data capacity is rapidly reaching its limit in modern optical communications. Optical vortex has been explored to enhance the data capacity for its extra degree of freedom of angular momentum. In traditional means, optical vortices are generated using space light modulators or spiral phase plates, which would sharply decrease the integration of optical communication systems. Here we experimentally demonstrate a planar chiral antenna array to produce optical vortex from a circularly polarized light. Furthermore, the antenna array has the ability to focus the incident light into point, which greatly increases the power intensity of the generated optical vortex. This chiral antenna array may have potential application in highly integrated optical communication systems. PMID:25988213

Fish scale terrace GaInN/GaN light-emitting diodes with enhanced light extraction

NASA Astrophysics Data System (ADS)

Stark, Christoph J. M.; Detchprohm, Theeradetch; Zhao, Liang; Paskova, Tanya; Preble, Edward A.; Wetzel, Christian

2012-12-01

Non-planar GaInN/GaN light-emitting diodes were epitaxially grown to exhibit steps for enhanced light emission. By means of a large off-cut of the epitaxial growth plane from the c-plane (0.06° to 2.24°), surface morphologies of steps and inclined terraces that resemble fish scale patterns could controllably be achieved. These patterns penetrate the active region without deteriorating the electrical device performance. We find conditions leading to a large increase in light-output power over the virtually on-axis device and over planar sapphire references. The process is found suitable to enhance light extraction even without post-growth processing.

Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture

NASA Astrophysics Data System (ADS)

Chen, Chih-Hung; Cambonie, Tristan; Lazarus, Veronique; Nicoli, Matteo; Pons, Antonio J.; Karma, Alain

2015-12-01

A planar crack generically segments into an array of "daughter cracks" shaped as tilted facets when loaded with both a tensile stress normal to the crack plane (mode I) and a shear stress parallel to the crack front (mode III). We investigate facet propagation and coarsening using in situ microscopy observations of fracture surfaces at different stages of quasistatic mixed-mode crack propagation and phase-field simulations. The results demonstrate that the bifurcation from propagating a planar to segmented crack front is strongly subcritical, reconciling previous theoretical predictions of linear stability analysis with experimental observations. They further show that facet coarsening is a self-similar process driven by a spatial period-doubling instability of facet arrays.

Development of Planar Optics for an Optical Tracking Sensor

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sasagawa, Tomohiro

1998-10-01

An optical tracking sensor for large-capacity flexible disk drive (FDD) is demonstrated. The passive optics is compact and lightweight (5.4 mm length×3.6 mm width×1.2 mm height in size and 18 mg weight). It comprises all passive optical elements necessary for optical tracking, e.g., a focusing lens, a three-beam grating, an aperture and a beam splitter grating. Three beams were focused to a predetermined spot size of 13 µm at designed intervals of 110 µm on a disk surface and the reflected beams were successfully guided to photodiodes. This confirms that the application of the planar optical technique is very useful for realizing a compact and light optical sensor.

Explosive-driven, high speed, arcless switch

DOEpatents

Skogmo, P.J.; Tucker, T.J.

1986-05-02

An explosive-actuated, fast-acting arcless switch contains a highly conductive foil to carry high currents positioned adjacent a dielectric surface within a casing. At one side of the foil opposite the dielectric surface is an explosive which, when detonated, drives the conductive foil against the dielectric surface. A pattern of grooves in the dielectric surface ruptures the foil to establish a rupture path having a pattern corresponding to the pattern of the grooves. The impedance of the ruptured foil is greater than that of the original foil to divert high current to a load. Planar and cylindrical embodiments of the switch are disclosed.

Surface dark screening solitons.

PubMed

Chen, W Q; Yang, X; Zhong, S Y; Yan, Z; Zhang, T H; Tian, J G; Xu, J J

2011-10-01

We report on the existence of surface dark screening solitons at the interface between a dielectric medium (air) and a self-defocusing nonlinear material, taking advantage of photorefractive diffusion and drift nonlinearities. It is very interesting that a surface dark soliton is just like half of a dark soliton in bulk, but not a whole dark soliton propagating along surface. The excitation, propagation, and stability of this type of soliton are studied by using the beam-propagation method. Another interesting thing is that this type of dark soliton can be excited by a planar light beam without a necessary dark notch. © 2011 Optical Society of America

Brittle strength of basaltic rock masses with applications to Venus

NASA Astrophysics Data System (ADS)

Schultz, R. A.

1993-06-01

Spacecraft images of surfaces with known or suspected basaltic composition on Venus (as well as on moon and Mars) indicate that these rocks have been deformed in the brittle regime to form faults and perhaps joints, in addition to folding and more distributed types of deformation. This paper presents results of detailed examinations and interpretations of Venus surface materials which show that the strengths of basaltic rocks on planetary surfaces and in the shallow subsurface are significantly different from strength values commonly used in tectonic modeling studies which assume properties of either intact rock samples or single planar shear surface.

Explosive-driven, high speed, arcless switch

DOEpatents

Skogmo, Phillip J.; Tucker, Tillman J.

1987-01-01

An explosive-actuated, fast-acting arcless switch contains a highly conductive foil to carry high currents positioned adjacent a dielectric surface within a casing. At one side of the foil opposite the dielectric surface is an explosive which, when detonated, drives the conductive foil against the dielectric surface. A pattern of grooves in the dielectric surface ruptures the foil to establish a rupture path having a pattern corresponding to the pattern of the grooves. The impedance of the ruptured foil is greater than that of the original foil to divert high current to a load. Planar and cylindrical embodiments of the switch are disclosed.

Development of Nomarski microscopy for quantitative determination of surface topography

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

Hartman, J. S.; Gordon, R. L.; Lessor, D. L.

1979-01-01

The use of Nomarski differential interference contrast (DIC) microscopy has been extended to provide nondestructive, quantitative analysis of a sample's surface topography. Theoretical modeling has determined the dependence of the image intensity on the microscope's optical components, the sample's optical properties, and the sample's surface orientation relative to the microscope. Results include expressions to allow the inversion of image intensity data to determine sample surface slopes. A commercial Nomarski system has been modified and characterized to allow the evaluation of the optical model. Data have been recorded with smooth, planar samples that verify the theoretical predictions.