Science.gov

Sample records for adhesive layer thickness

  1. Adhesive wafer bonding using a molded thick benzocyclobutene layer for wafer-level integration of MEMS and LSI

    NASA Astrophysics Data System (ADS)

    Makihata, M.; Tanaka, S.; Muroyama, M.; Matsuzaki, S.; Yamada, H.; Nakayama, T.; Yamaguchi, U.; Mima, K.; Nonomura, Y.; Fujiyoshi, M.; Esashi, M.

    2011-08-01

    This paper describes a wafer bonding process using a 50 µm thick benzocyclobutene (BCB) layer which has vias and metal electrodes. The vias were fabricated by molding BCB using a glass mold. During the molding, worm-like voids grew between BCB and the mold due to the shrinkage of polymerizing BCB. They were completely removed by subsequent reflowing in N2. After patterning Al on the reflowed BCB for the electrodes and via connections, bonding with a glass substrate was performed. Voidless bonding without damage in the vias and electrodes was achieved. Through the process, the control of the polymerization degree of BCB is important, and thus the polymerization degree was evaluated by Fourier transform infrared spectroscopy. The developed process is useful for the wafer-bonding-based integration of different devices, e.g. micro electro mechanical systems and large-scale integrated circuits.

  2. Effect of adhesive thickness on adhesively bonded T-joint

    NASA Astrophysics Data System (ADS)

    Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

    2013-12-01

    The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

  3. Adhesive behavior of aluminum layers evaporated on polyester films

    SciTech Connect

    Vallat, M.F.; Haidara, H.; Ziegler, P.; Rey, D.; Papirer, Y.; Schultz, J.

    1996-01-01

    The adhesive performance of thin aluminum coatings deposited onto polymer substrates is considered. The effects of the evaporation conditions and the metal thickness on the adhesive properties of polyester/aluminum assemblies are examined. A ultrasonic test for adherence measurements of thin metal layers is proposed and its shown that a thermal treatment under stress modifies the adhesive properties of such metallized polymer films. (AIP) {copyright}{ital 1996 American Institute of Physics.}

  4. The impact of Cr adhesion layer on CNFET electrical characteristics

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Chikkadi, Kiran; Muoth, Matthias; Hierold, Christofer; Haluska, Miroslav

    2016-01-01

    The effect of a Cr adhesion layer on the transfer characteristics of Cr/Au-contacted carbon nanotube field-effect transistors (CNFETs) based on individual single-walled carbon nanotubes (SWNTs) is presented in this paper. We show that a very thin Cr layer (≈0.4 nm) already has an impact on the carrier transport in Schottky-barrier-modulated CNFETs. The ratio of the p- and n-branch current is reduced by eight times when the Cr adhesion layer thickness is increased from 0 to 8 nm. We suggest a change in Schottky barrier height at the contact as the determining mechanism for this result. Additionally, superior lifetime of devices is observed even for non-passivated CNFETs with preserved clean SWNT/Cr/Au-contacts using Cr layer thinner than 2 nm. Our experiments show that the role of the adhesion layer in metal/nanotube contacts should be explicitly considered when designing CNTFET-based circuits, developing CNFET fabrication processes, and analyzing the corresponding properties of the electrical contacts.

  5. Tuning the acoustic frequency of a gold nanodisk through its adhesion layer

    NASA Astrophysics Data System (ADS)

    Chang, Wei-Shun; Wen, Fangfang; Chakraborty, Debadi; Su, Man-Nung; Zhang, Yue; Shuang, Bo; Nordlander, Peter; Sader, John E.; Halas, Naomi J.; Link, Stephan

    2015-05-01

    To fabricate robust metallic nanostructures with top-down patterning methods such as electron-beam lithography, an initial nanometer-scale layer of a second metal is deposited to promote adhesion of the metal of interest. However, how this nanoscale layer affects the mechanical properties of the nanostructure and how adhesion layer thickness controls the binding strength to the substrate are still open questions. Here we use ultrafast laser pulses to impulsively launch acoustic phonons in single gold nanodisks with variable titanium layer thicknesses, and observe an increase in phonon frequencies as a thicker adhesion layer facilitates stronger binding to the glass substrate. In addition to an all-optical interrogation of nanoscale mechanical properties, our results show that the adhesion layer can be used to controllably modify the acoustic phonon modes of a gold nanodisk. This direct coupling between optically excited plasmon modes and phonon modes can be exploited for a variety of emerging optomechanical applications.

  6. MEASUREMENTS OF CONFORMATION CHANGES DURING ADHESION OF LIPID PROTEIN (POLYLYSINE AND S-LAYER) SURFACES

    EPA Science Inventory

    The adhesion forces between various surfaces were measured using the "surface forces apparatus" technique which allows for the thickness of surface layers and the adhesion force between them to be directly measured in controlled vapor or liquid environments. hree types of biologi...

  7. Effects of adhesive thickness on the Lamb wave pitch-catch signal using bonded piezoelectric wafer transducers

    NASA Astrophysics Data System (ADS)

    Islam, M. M.; Huang, H.

    2016-08-01

    This paper investigates the effects of adhesive layer on Lamb wave ultrasound pitch-catch signals that are excited and sensed by piezoelectric wafer transducers bonded on a slender structure. Analytical models were established to simulate the longitudinal and flexural vibrations of the structures separately and parametric studies of the bonding layer properties, i.e. the shear transfer parameter, adhesive thickness, and shear modulus, were performed. The parametric studies indicate that there exists an optimal adhesive layer thickness that generates maximum ultrasound pitch-catch signal for both wave modes. This prediction was subsequently validated by measurements. In addition, an improved match between the measured and simulated pitch-catch signals was achieved by adjusting the adhesive layer parameters.

  8. Influence of cement type and thickness on polyfiber post adhesion

    PubMed Central

    Uzunoğlu, Emel; Türker, Sevinç Aktemur; Yilmaz, Zeliha

    2014-01-01

    Introduction: To evaluate the effect of two different post space diameters and related resin cement film thicknesses on the bond strength of a polyfiber post. Materials and Methods: A total of 48 premolars were randomly divided into two according to the post space diameter: 1.1 mm and 1.5 mm. Then each group was divided into three sub-groups according to luting cement used: RelyX U100, Panavia F2.0/ED primer, Clearfil SA cement. Spirapost was then luted into the canal using luting cements. Two slices were obtained from each root specimen. Push-out tests were performed. Data was analyzed with Kruskal-Wallis and Connover post-hoc and Mann-Whitney U-test (P < 0.05). Results: Push-out bond strength was found to vary significantly according to type of adhesive system and post space diameter size (P < 0.05). The self-adhesive resin cement RelyX U100 had significantly higher bond strengths compared with the other adhesive system (P < 0.05). The self-etch adhesive system (Panavia F2.0) showed significantly lower bond strengths compared with the other systems (P < 0.05). There was a significant interaction between the luting systems and post space diameter (P < 0.05). Conclusion: The increases in post space diameter significantly reduced the bond strength of Spirapost to root dentine for both groups. PMID:24944450

  9. The effect of chrome adhesion layer on quartz resonator aging.

    SciTech Connect

    Wessendorf, Kurt O.; Ohlhausen, James Anthony

    2011-03-01

    This SAND report documents a late start LDRD designed to determine the possible aging effects of a quartz resonator gold adhesion layer. Sandia uses quartz resonators for applications. These applications require a very stable frequency source with excellent aging (low drift) characteristics. These parts are manufactured by one of our qualified vendors outside Sandia Laboratories, Statek Corp. Over the years we, Sandia and the vendor, have seen aging variations that have not been completely explained by the typical mechanisms known in the industry. One theory was that the resonator metallization may be contributing to the resonator aging. This LDRD would allow us to test and analyze a group of resonators with known differentiating metallization and via accelerated aging determine if a chrome adhesion layer used to accept the final gold plating may contribute to poor aging. We worked with our main vendor to design and manufacture a set of quartz resonators with a wide range of metallization thickness ratios between the chrome and gold that will allow us determine the cause of this aging and which plating thickness ratios provide the best aging performance while not degrading other key characteristics.

  10. Effect of Ti adhesive layer on individual gold nanodisk surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Debu, Desalegn Tadesse; Ghosh, Pijush; French, David; Bauman, Stephen; Herzog, Joseph B.

    We investigate localized surface plasmon resonance (SPR) of gold nanodisks of various diameter and height fabricated on extremely thin Ti adhesive layers. Dark field scattering measurements reveal significant dependence of SPR in the size nano structures and polarization of the light. Comparisons of peak resonance extracted from spectra using Gaussian fitting of different Ti adhesive layer thickness indicates significant red shifting and damping of the plasmon mode. Experimental results are supported by numerical simulation based on three dimensional finite element time domain analysis. From the simulation and experimental results we quantitatively developed optimized model equation of resonance mode of the nanodisks with respect to adhesive layer thickness and broadening effect of the line shape. Such optimized model is very helpful in guiding targeted nanofabrication such as gold nanodisk antennas or biosensors.

  11. Cross-sectional nanoindentation (CSN) studies on the effect of thickness on adhesion strength of thin films

    NASA Astrophysics Data System (ADS)

    Roshanghias, A.; Khatibi, G.; Pelzer, R.; Steinbrenner, J.; Bernardi, J.

    2015-01-01

    In this study the cross-sectional nanoindentation (CSN) technique has been employed to investigate the adhesion behavior of Titanium-Tungsten (TiW) thin films in various thicknesses on silicon substrate. Furthermore, the nanoindentation-induced blister (NIB) technique has been implemented on the same samples to evaluate the adhesion energy of the films with a different approach. The adhesion energy release rate of these thin films, derived by these two techniques, revealed a good agreement. Accordingly, the results show that as the thickness of the TiW layer increases, the adhesion toughness of the film decreases. It was suggested that three factors might be responsible for the superior adhesion strength of thin films with lower thicknesses: higher surface energy due to the smaller mean grain size; higher constraint from the substrate, which causes inferior fracture toughness of the coating and facilitates crack deflection from interface to surface; and, energy dissipation due to decohesion. The thickness dependency of the transition between delamination and decohesion mechanism in thin films has also been discussed and modelled.

  12. Peeling off an adhesive layer with spatially varying topography and shear modulus.

    PubMed

    Ghatak, Animangsu

    2014-03-01

    Inspired by recent experiments on hierarchically structured adhesives, we analyze here the effect of spatial variation in surface topography and shear modulus of an elastomeric adhesive on its ability to adhere strongly to a flexible contactor. The undulation of surface and modulus both were assumed to be periodic with periodicity, which is either identical or different for the two parameters; for identical periodicity, the phase lag between the respective undulations is also systematically varied. Calculations show that during continuous lifting of the flexible contactor from complete initial contact, the interfacial crack between the two adherents does not propagate continuously but intermittently, with crack arrest and initiation at the vicinity of minimum thickness and modulus of the layer; the torque required to initiate an arrested crack increases significantly over that required to propagate it on a smooth adhesive surface. The adhesion strength estimated from the corresponding force vs displacement plot is calculated to be higher than that achieved on a smooth and featureless adhesive surface. For in-phase variation in topography and shear modulus of the layer, the adhesive strength is found to be higher than for nonzero phase lag between the two parameters. The adhesion strength is found to diminish also for nonidentical periodicity between modulus and surface undulation. We have derived a scaling law for relating adhesion strength to several of these parameters. PMID:24730852

  13. Adhesion layer for etching of tracks in nuclear trackable materials

    DOEpatents

    Morse, Jeffrey D.; Contolini, Robert J.

    2001-01-01

    A method for forming nuclear tracks having a width on the order of 100-200 nm in nuclear trackable materials, such as polycarbonate (LEXAN) without causing delamination of the LEXAN. The method utilizes an adhesion film having a inert oxide which allows the track to be sufficiently widened to >200 nm without delamination of the nuclear trackable materials. The adhesion film may be composed of a metal such as Cr, Ni, Au, Pt, or Ti, or composed of a dielectric having a stable surface, such as silicon dioxide (SiO.sub.2), silicon nitride (SiN.sub.x), and aluminum oxide (AlO). The adhesion film can either be deposited on top of the gate metal layer, or if the properties of the adhesion film are adequate, it can be used as the gate layer. Deposition of the adhesion film is achieved by standard techniques, such as sputtering or evaporation.

  14. Graphene thickness dependent adhesion force and its correlation to surface roughness

    SciTech Connect

    Pourzand, Hoorad; Tabib-Azar, Massood

    2014-04-28

    In this paper, adhesion force of graphene layers on 300 nm silicon oxide is studied. A simple model for measuring adhesion force for a flat surface with sub-nanometer roughness was developed and is shown that small surface roughness decreases adhesion force while large roughness results in an effectively larger adhesion forces. We also show that surface roughness over scales comparable to the tip radius increase by nearly a factor of two, the effective adhesion force measured by the atomic force microscopy. Thus, we demonstrate that surface roughness is an important parameter that should be taken into account in analyzing the adhesion force measurement results.

  15. Adhesion in the contact of a spherical indenter with a layered elastic half-space

    NASA Astrophysics Data System (ADS)

    Onur Sergici, A.; Adams, George G.; Müftü, Sinan

    2006-09-01

    With the emergence of micro- and nano-technology, the contact mechanics of MEMS and NEMS devices and components is becoming more important. Thus it is important to gain a better understanding of the role of coatings and thin films on micro- and nano-scale contact phenomena, and to understand the interactions of measurement devices, such as an atomic force microscope (AFM), with layered media. More specifically, in this work the frictionless contact, with adhesion, between a spherical indenter and an elastic-layered medium is investigated. This configuration can be viewed as either a single contact model or as a building block of a multi-asperity rough surface contact model. As the scale decreases to the nano level, adhesion becomes an important issue. The presence of adhesion affects the relationships among the applied force, the penetration of the indenter, and the size of the contact area. This axisymmetric problem includes the effect of adhesion using a Maugis type of adhesion model. This model spans the range of the Tabor parameter between the JKR and DMT regions. The key parameters in this analysis are the elastic moduli ratio of the layer and the substrate, the dimensionless layer thickness, and the Maugis adhesion parameter. The results can be applied to a rigid or to an elastic indenter.

  16. Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength.

    PubMed

    Bijelic-Donova, Jasmina; Garoushi, Sufyan; Lassila, Lippo V J; Vallittu, Pekka K

    2015-02-01

    An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short-fiber-reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short-fiber-reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical-shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000-grit silicon-carbide (SiC) abrasive paper, or treatment with ethanol or with water-spray. The inhibition depth was lowest (11.6 μm) for water-sprayed Silorane and greatest (22.9 μm) for the water-sprayed short-fiber-reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water-sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short-fiber-reinforced composite. Thus, more durable adhesion with short-fiber-reinforced composite is expected. PMID:25556290

  17. Time-domain ultrasonic measurement of the thickness of a sub-half-wavelength elastic layer

    NASA Astrophysics Data System (ADS)

    Zhu, Changyi; Kinra, Vikram K.

    1992-07-01

    A technique is reported for the ultrasonic nondestructive measurement of the thickness of extremely thin (sub-wavelength) adhesive layers in adhesively bonded joints without the use of Fourier transforms. The entire ultrasonic NDE is carried out in the time domain and can be used by a trained technician without a college education. Aluminum plates ranging in thickness from 0.089 to 12.675 mm were tested using a 1-MHz transducer. The error was found to be one percent for h/lambda (specimen thickness/wavelength) down to 0.010. In dimensional terms, plates with a thickness of 100 microns can be measured with an accuracy of + or - 1 micron. This technique can also be used in conjunction with the electromagnetic-acoustic transducer technology in which only low-frequency transducers are presently available.

  18. Veneer vs. core failure in adhesively bonded all-ceramic crown layers.

    PubMed

    Lee, J J-W; Kwon, J-Y; Bhowmick, S; Lloyd, I K; Rekow, E D; Lawn, B R

    2008-04-01

    Joining a brittle veneer to a strong ceramic core with an adhesive offers potential benefits over current fabrication methods for all-ceramic crowns. We tested the hypothesis that such joining can withstand subsurface radial cracking in the veneer, from enhanced flexure in occlusal loading, as well as in the core. Critical conditions to initiate fractures were investigated in model crown-like layer structures consisting of glass veneers epoxy-joined onto alumina or zirconia cores, all bonded to a dentin-like polymer base. The results showed a competition between critical loads for radial crack initiation in the veneers and cores. Core radial cracking was relatively independent of adhesive thickness. Zirconia cores were much less susceptible to fracture than alumina, attributable to a relatively high strength and low modulus. Veneer cracking did depend on adhesive thickness. However, no significant differences in critical loads for veneer cracking were observed for specimens containing alumina or zirconia cores. PMID:18362320

  19. The effect of adhesive layer on crack propagation in laminates

    NASA Technical Reports Server (NTRS)

    Gecit, M. R.; Erdogan, F.

    1976-01-01

    The effect of the adhesive layer on crack propagation in composite materials is investigated. The composite medium consists of parallel load carrying laminates and buffer strips arranged periodically and bonded with thin adhesive layers. The strips, assumed to be isotropic and linearly elastic, contain symmetric cracks of arbitrary lengths located normal to the interfaces. Two problems are considered: (1) thin adhesive layers are approximated by uncoupled tension and shear springs distributed along the interfaces of the strips for which only the case of internal cracks can be treated rigorously; (2) broken laminates and the true singular behavior in the presence of the adhesive layer are studied. The adhesive is then treated as an isotropic, linearly elastic continuum. General expressions for field quantities are obtained in terms of infinite Fourier integrals. These expressions give a system of singular integral equations in terms of the crack surface displacement derivatives. By using appropriate quadrature formulas, the integral equations reduce to a system of linear algebraic equations which are solved numerically.

  20. Super-adhesive polymer-silica nanocomposite layers.

    PubMed

    Wood, T J; Ward, L J; Badyal, J P S

    2013-10-01

    Atomized spray plasma deposition (ASPD) using a precursor mixture of 2-hydroxyethyl methacrylate and methacryloyl-functionalized 15 nm silica nanoparticles leads to the formation of poly(2-hydroxyethyl methacrylate)-silica nanocomposite layers. The direct application of these coatings to overlapping glass-glass joints gives rise to excellent in situ adhesion reaching 84 MPa shear bond strength and 6 GPa shear modulus prior to the onset of adherent (bulk glass) failure. This significant enhancement in interfacial adhesion arises due to the silica nanoparticle surface methacryloyl groups enhancing cross-linking throughout the nanocomposite layer. PMID:24079883

  1. Nanometer-thick hyaluronic acid self-assemblies with strong adhesive properties.

    PubMed

    Marais, Andrew; Pendergraph, Samuel; Wågberg, Lars

    2015-07-22

    The adhesive characteristics of poly(allylamine hydrochloride) (PAH)/hyaluronic acid (HA) self-assemblies were investigated using contact adhesion testing. Poly(dimethylsiloxane) spheres and silicon wafers were coated with layer-by-layer (LbL) assemblies of PAH/HA. No increase in adhesion was observed when surfaces covered with dried LbL films were placed in contact. However, bringing the coated surfaces in contact while wet and separating them after drying resulted in an increase by a factor of 100 in the work of adhesion (from one to three bilayers). Herein we discuss the adhesion in PAH/HA and PAH/poly(acrylic acid) assemblies. PAH/HA assemblies have potential application as strong biomedical adhesives. PMID:26151110

  2. An elevated temperature study of a Ti adhesion layer on polyimide

    PubMed Central

    Taylor, A.A.; Cordill, M.J.; Bowles, L.; Schalko, J.; Dehm, G.

    2013-01-01

    Titanium layers are used to promote adhesion between polymer substrates for flexible electronics and the Cu or Au conducting lines. Good adhesion of conducting lines in flexible circuits is critical in improving circuit performance and increasingcircuit lifetime. Nominally 50 nm thick Ti films on polyimide (PI) are investigated by fragmentation testing under uniaxial tensile load in the as-deposited state, at 350 °C, and after annealing. The cracking and buckling of the films show clear differences between the as-deposited and the thermally treated samples, cracks are much straighter and buckles are smaller following heat treatment. These changes are correlated to a drop in adhesion of the samples following heat treatment. Adhesion values are determined from the buckle dimensions using a total energy approach as described in the work of Cordill et al. (Acta Mater. 2010). Cross-sectional transmission electron microscopy of the Ti/PI interface found evidence of a ~ 5 nm thick interlayer between the largely columnar Ti and the amorphous PI. This interlayer is amorphous in the as-deposited state but nano-crystalline in those coatings tested at elevated temperature or annealed. It is put forward that this alteration of the interfacial structure causes the reduced adhesion. PMID:23525510

  3. Enhanced adhesion buffer layer for deep x-ray lithography using hard x-rays.

    SciTech Connect

    De Carlo, F.

    1998-08-28

    The first step in the fabrication of microstructure using deep x-ray lithography (DXRL) is the irradiation of a x-ray sensitive resist like polymethylmethacrylate (PMMA) by hard x-rays. At the Advanced Photon Source, a dedicated beamline allows the proper exposure of very thick (several mm) resists. To fabricate electroformed metal microstructure with heights of several mm, a PMMA sheet is glued onto a metallic plating base. An important requirement is that the PMMA layer must adhere well to the plating base. The adhesion is greatly reduced by the penetration of even a small fraction of hard x-rays through the mask absorber into the substrate. In this work we will show a novel technique to improve the adhesion of PMMA onto high-Z substrates for DXRL. Results of the improved adhesion are shown for different exposure/substrate conditions.

  4. Adhesion of functional layer on polymeric substrates for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Amendola, E.; Cammarano, A.; Pezzuto, M.; Acierno, D.

    2009-06-01

    The use of plastic film substrates for organic electronic devices promises to enable new applications, such as flexible displays. Plastic substrates have several distinct advantages, such as ruggedness, robustness, ultra lightness, conformability and impact resistance over glass substrates, which are primarily used in flat panel displays (FPDs) today. However, high transparency, proper surface roughness, low gas permeability and high transparent electrode conductivity of the plastic substrate are required for commercial applications. Polyesters, both amorphous and semicrystalline, are a promising class of commercial polymer for optoelectronic applications. Surface modification of polyester films was performed via chemical solution determining hydrolysis or oxidation. Hydrolysis was carried out by means of sodium hydroxide solution and oxidation by using standard clean 1 (SC-1) of RCA procedure [1]. For this work we have used commercial polymer films of 100μm in thickness: AryLite [2], supplied by Ferrania Imaging Technologies S.p.A. and characterised by very high glass transition temperature, Mylar (Polyethylene Terephthalate PET) and Teonex (Polyethylene Naphthalate PEN) both supplied by Dupont. More over, a bioriented and semicrystalline PET have been used. The aim of this study is modifying the polymer surface to improve the adhesion between organic-inorganic layer. It was found that the NaOH and SC-1 treatment cause a decrease of contact angles. In the present study we have deposited a thin films of amorphous hydrogenated silicon (a-Si:H) and its oxide (SiO2) on a new high temperature polymer substrate, AryLite, by plasma enhanced chemical vapour deposition (PECVD) [3], with a radio frequency plasma system.

  5. Effects of surface roughness and film thickness on the adhesion of a bioinspired nanofilm

    NASA Astrophysics Data System (ADS)

    Peng, Z. L.; Chen, S. H.

    2011-05-01

    Inspired by the gecko's climbing ability, adhesion between an elastic nanofilm with finite length and a rough substrate with sinusoidal roughness is studied in the present paper, considering the effects of substrate roughness and film thickness. It demonstrates that the normal adhesion force of the nanofilm on a rough substrate depends significantly on the geometrical parameters of the substrate. When the film length is larger than the wavelength of the sinusoidal roughness of the substrate, the normal adhesion force decreases with increasing surface roughness, while the normal adhesion force initially decreases then increases if the wavelength of roughness is larger than the film length. This finding is qualitatively consistent with a previously interesting experimental observation in which the adhesion force of the gecko spatula is found to reduce significantly at an intermediate roughness. Furthermore, it is inferred that the gecko may achieve an optimal spatula thickness not only to follow rough surfaces, but also to saturate the adhesion force. The results in this paper may be helpful for understanding how geckos overcome the influence of natural surface roughness and possess such adhesion to support their weights.

  6. Reliability of Intra-Retinal Layer Thickness Estimates

    PubMed Central

    Oberwahrenbrock, Timm; Weinhold, Maria; Mikolajczak, Janine; Zimmermann, Hanna; Paul, Friedemann; Beckers, Ingeborg; Brandt, Alexander U.

    2015-01-01

    Purpose Measurement of intra-retinal layer thickness using optical coherence tomography (OCT) has become increasingly prominent in multiple sclerosis (MS) research. Nevertheless, the approaches used for determining the mean layer thicknesses vary greatly. Insufficient data exist on the reliability of different thickness estimates, which is crucial for their application in clinical studies. This study addresses this lack by evaluating the repeatability of different thickness estimates. Methods Studies that used intra-retinal layer segmentation of macular OCT scans in patients with MS were retrieved from PubMed. To investigate the repeatability of previously applied layer estimation approaches, we generated datasets of repeating measurements of 15 healthy subjects and 13 multiple sclerosis patients using two OCT devices (Cirrus HD-OCT and Spectralis SD-OCT). We calculated each thickness estimate in each repeated session and analyzed repeatability using intra-class correlation coefficients and coefficients of repeatability. Results We identified 27 articles, eleven of them used the Spectralis SD-OCT, nine Cirrus HD-OCT, two studies used both devices and two studies applied RTVue-100. Topcon OCT-1000, Stratus OCT and a research device were used in one study each. In the studies that used the Spectralis, ten different thickness estimates were identified, while thickness estimates of the Cirrus OCT were based on two different scan settings. In the simulation dataset, thickness estimates averaging larger areas showed an excellent repeatability for all retinal layers except the outer plexiform layer (OPL). Conclusions Given the good reliability, the thickness estimate of the 6mm-diameter area around the fovea should be favored when OCT is used in clinical research. Assessment of the OPL was weak in general and needs further investigation before OPL thickness can be used as a reliable parameter. PMID:26349053

  7. Atomic layer deposition of ultrathin platinum films on tungsten atomic layer deposition adhesion layers: Application to high surface area substrates

    SciTech Connect

    Clancey, Joel W.; Cavanagh, Andrew S.; Kukreja, Ratandeep S.; Kongkanand, Anusorn; George, Steven M.

    2015-01-15

    Platinum (Pt) atomic layer deposition (ALD) usually yields Pt nanoparticles during initial film growth. In contrast, deposition of continuous and ultrathin Pt films is needed for many important applications, such as the oxygen reduction reaction in polymer electrolyte membrane (PEM) fuel cells. A continuous and high radius of curvature Pt film is more stable and has a higher area-specific activity than the Pt nanoparticles commonly used in PEM fuel cells. However, the Pt film must be ultrathin and have a large surface area to be cost effective. In this paper, a review of earlier Pt ALD studies on flat substrates is presented that demonstrates that tungsten, with a higher surface energy than platinum, can serve as an adhesion layer to achieve Pt ALD films that are continuous at ultrathin thicknesses of ∼1.5 nm. This work utilized MeCpPtMe{sub 3} and H{sub 2} plasma as the Pt ALD reactants. The deposition of continuous and ultrathin Pt ALD films using MeCpPtMe{sub 3} and H{sub 2} plasma as the reactants is then studied on two high surface area substrate materials: TiO{sub 2} nanoparticles and 3M nanostructured thin film (NSTF). Transmission electron microscopy (TEM) showed uniform and continuous Pt films with thicknesses of ∼4 nm on the TiO{sub 2} nanoparticles. TEM with electron energy loss spectroscopy analysis revealed W ALD and Pt ALD films with thicknesses of ∼3 nm that were continuous and conformal on the high aspect ratio NSTF substrates. These results demonstrate that cost effective use of Pt ALD on high surface area substrates is possible for PEM fuel cells.

  8. Enhancing cell-free layer thickness by bypass channels in a wall.

    PubMed

    Saadatmand, M; Shimogonya, Y; Yamaguchi, T; Ishikawa, T

    2016-07-26

    When blood flows near a wall, red blood cells (RBCs) drift away from the wall and a cell-free layer (CFL) is formed adjacent to the wall. Controlling the CFL thickness is important for preventing adhesion of cells in the design of biomedical devices. In this study, a novel wall configuration with stenoses and bypass channels is proposed to increase the CFL thickness. We found that the presence of bypass channels modified the spatial distribution of cells and substantially increased the CFL downstream of the stenosis. A single-bypass geometry with 5% hematocrit (Hct) blood flow showed a 1.7μm increase in CFL thickness compared to without the bypass. In the case of three bypass channels, a 3μm increase in CFL thickness was observed. The CFL enhancement was observed up to 10% Hct, but no significant enhancement of CFL was indicated for 20% Hct blood flow. The mechanism of the CFL enhancement was investigated using a numerical simulation of the flow field. The results showed that the distance between each streamline and the corner of the stenosis compared with size of RBC was important parameter in regulating CFL thickness. These results show the potential of the proposed mechanism to prevent adhesion of cells to biomedical devices. PMID:26803337

  9. Effect of Thickness of a Water Repellent Soil Layer on Soil Evaporation Rate

    NASA Astrophysics Data System (ADS)

    Ahn, S.; Im, S.; Doerr, S.

    2012-04-01

    A water repellent soil layer overlying wettable soil is known to affect soil evaporation. This effect can be beneficial for water conservation in areas where water is scarce. Little is known, however, about the effect of the thickness of the water repellent layer. The thickness of this layer can vary widely, and particularly after wildfire, with the soil temperature reached and the duration of the fire. This study was conducted to investigate the effect of thickness of a top layer of water repellent soil on soil evaporation rate. In order to isolate the thickness from other possible factors, fully wettable standard sand (300~600 microns) was used. Extreme water repellency (WDPT > 24 hours) was generated by 'baking' the sand mixed with oven-dried pine needles (fresh needles of Pinus densiflora) at the mass ratio of 1:13 (needle:soil) at 185°C for 18 hours. The thicknesses of water repellent layers were 1, 2, 3 and 7 cm on top of wettable soil. Fully wettable soil columns were prepared as a control. Soil columns (8 cm diameter, 10 cm height) were covered with nylon mesh. Tap water (50 ml, saturating 3 cm of a soil column) was injected with hypoderm syringes from three different directions at the bottom level. The injection holes were sealed with hot-melt adhesive immediately after injection. The rate of soil evaporation through the soil surface was measured by weight change under isothermal condition of 40°C. Five replications were made for each. A trend of negative correlation between the thickness of water repellent top layer and soil evaporation rate is discussed in this contribution.

  10. Automated segmentation of intraretinal layers from spectral-domain macular OCT: reproducibility of layer thickness measurements

    NASA Astrophysics Data System (ADS)

    Lee, Kyungmoo; Abràmoff, Michael D.; Sonka, Milan; Garvin, Mona K.

    2011-03-01

    Changes in intraretinal layer thickness occur in a variety of diseases such as glaucoma, macular edema and diabetes. To segment the intraretinal layers from macular spectral-domain OCT (SD-OCT) scans, we previously introduced an automated multiscale 3-D graph search method and validated its performance by computing unsigned border positioning differences when compared with human expert tracings. However, it is also important to study the reproducibility of resulting layer thickness measurements, as layer thickness is a commonly used clinical parameter. In this work, twenty eight (14 x 2) repeated macular OCT volumes were acquired from the right eyes of 14 normal subjects using two Zeiss-Cirrus SD-OCT scanners. After segmentation of 10 intraretinal layers and rigid registration of layer thickness maps from the repeated OCT scans, the thickness difference of each layer was calculated. The overall mean global and regional thickness differences of 10 intraretinal layers were 0.46 +/- 0.25 μm (1.70 +/- 0.72 %) and 1.16 +/- 0.84 μm (4.03 +/- 2.05 %), respectively. No specific local region showed a consistent thickness difference across the layers.

  11. Determination of graphene layer thickness using optical image processing

    NASA Astrophysics Data System (ADS)

    Cook, Monica; Mani, R. G.

    2015-03-01

    Graphene, a single atomic layer of carbon arranged in a hexagonal lattice structure, is a valuable material in a wide range of research. A significant impediment to graphene research is the need to manually characterize the thickness of high-quality graphene produced via mechanical exfoliation. Traditional methods of characterizing the layer thickness of graphene, including Raman spectroscopy and atomic force microscopy, require expensive equipment and can be damaging to the graphene sample. We examine here a known alternative method for quantitatively determining the layer thickness of graphene on SiO2/Si based on optical image processing, which is quick, inexpensive, and non-invasive. Using RGB images of a candidate graphene sample and a background image, taken with a simple optical microscope and charge-coupled device (CCD) camera, we process the images with an algorithm based on Fresnel's law to obtain the contrast spectrum. Each layer of graphene exhibits a unique contrast spectrum for its particular substrate, which is measured and used for accurate layer identification. We also discuss how this algorithm can be generalized to characterize the thickness of other promising two-dimensional materials as well as more complex structures on a variety of substrates.

  12. Surface modulation of complex stiffness via layer-by-layer assembly as a facile strategy for selective cell adhesion.

    PubMed

    Chang, Hao; Zhang, He; Hu, Mi; Chen, Xia-chao; Ren, Ke-feng; Wang, Jin-lei; Ji, Jian

    2015-02-01

    In-stent restenosis and thrombosis are the main severe problems that occur after the percutaneous vascular intervention. The competition between endothelial cells (ECs) and smooth muscle cells (SMCs) plays a key role during these pathological changes. The regulation of this competition offers new opportunities to design biomaterials in the cardiovascular fields. Bioactive molecules have been typically employed to increase EC adhesion and thereafter to enhance EC competitiveness; however, this method is associated with limitations from the point of view of practical and industrial applications. Herein, we present an approach to enhance EC competitiveness over that of SMC through the selective EC adhesion, which is achieved by modulating a complex surface stiffness based on the technique of layer-by-layer (LbL) assembly. This complex stiffness can be achieved by regulating the thickness of multilayer films coordinating with a rigid underlying substrate. The selective cell adhesion is attributed to changes in the complex surface stiffness and a different intrinsic property between ECs and SMCs. This study provides a facile and broadly applicable approach for the purpose of the enhancement of EC competitiveness over that of SMC, which has great potential for the development of cell-based functional biomaterials in the cardiovascular field. PMID:26218126

  13. B Layers and Adhesion on Armco Iron Substrate

    NASA Astrophysics Data System (ADS)

    Elias-Espinosa, M.; Ortiz-Domínguez, M.; Keddam, M.; Flores-Rentería, M. A.; Damián-Mejía, O.; Zuno-Silva, J.; Hernández-Ávila, J.; Cardoso-Legorreta, E.; Arenas-Flores, A.

    2014-08-01

    In this work, a kinetic model was suggested to evaluate the boron diffusion coefficient in the Fe2B layers grown on the Armco iron substrate by the powder-pack boriding. This thermochemical treatment was carried out in the temperature range of 1123-1273 K for treatment times ranging from 2 to 8 h. The boron diffusion coefficient in the Fe2B layers was estimated by solving the mass balance equation at the (Fe2B/substrate) interface with an inclusion of boride incubation time. To validate the present model, the simulated value of Fe2B layer thickness was compared with the experimental value obtained at 1253 K for a treatment time of 5 h. The morphology of Fe2B layers was observed by SEM and optical microscopy. Metallographic studies showed that the boride layer has a saw-tooth morphology in all the samples. The layer thickness measurements were done with the help of MSQ PLUS software. The Fe2B phase was identified by x-ray diffraction method. Finally, the adherence of Fe2B layers on the Armco iron substrate was qualitatively evaluated by using the Daimler-Benz Rockwell-C indentation technique. In addition, the estimated value of boron activation energy was compared to the literature data.

  14. Effect of adhesive thickness and surface treatment on shear strength on single lap joint Al/CFRP using adhesive of epoxy/Al fine powder

    NASA Astrophysics Data System (ADS)

    Diharjo, Kuncoro; Anwar, Miftahul; Tarigan, Roy Aries P.; Rivai, Ahmad

    2016-02-01

    The objective of this study is to investigate the effect of adhesive thickness and surface treatment on the shear strength and failure type characteristic of single lap joint (SLJ) CFRP/Al using adhesive epoxy/Al-fine-powder. The CFRP was produced by using hand layup method for 30% of woven roving carbon fiber (w/w) and the resin used was bisphenolic. The adhesive was prepared using 12.5% of aluminum fine powder (w/w) in the epoxy adhesive. The powder was mixed by using a mixing machine at 60 rpm for 6 minutes, and then it was used to join the Al plate-2024 and CFRP. The start time to pressure for the joint process was 20 minutes after the application of adhesive on the both of adherends. The variables in this research are adhesive thickness (i.e. 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm and 1 mm) and surface treatment of adherends (i.e. acetone, chromate sulphuric acid, caustic etch and tucker's reagent). Before shear testing, all specimens were post-cured at 100 °C for 15 minutes. The result shows that the SLJ has the highest shear strength for 0.4 mm of adhesive thickness. When the adhesive thickness is more than 0.4 mm (0.6-1 mm), the shear strength decreases significantly. It might be caused by the property change of adhesive from ductile to brittle. The acetone surface treatment produces the best bonding between the adhesive and adherends (CFRP and Al-plate 2024), and the highest shear strength is 9.31 MPa. The surface treatment give the humidification effect of adherend surfaces by adhesive. The failure characteristic shows that the mixed failure of light-fiber-tear-failure and cohesive-failure are occurred on the high shear strength of SLJ, and the low shear strength commonly has the adhesive-failure type.

  15. A Proposal of Evaluation of Frost Layer Thickness

    NASA Astrophysics Data System (ADS)

    Yotsumoto, Hiroyuki; Ishihara, Isao; Tanio, Kenichi; Matsumoto, Ryosuke

    The frosting is an unsteady phenomenon occurs simultaneously with heat and mass transfer. Both the heat and water vapor in the humid air reach the surface of the frost layer and transfer to the cold surface. The frost surface plays an important role as an interface of heat and mass transfer between air-flow and ice-air composite solid layer. However, since the frost layer surface consists of ice and air, and is rough and unsteady, any specific definition of the frost layer thickness is not found. This paper tried to give the definition. The frost layer thickness was measured by using a micro photo-sensing device combined with a light emitter and receiver traversing normal to the frost surface. During traversing the device, a peak response from the device indicates the vertical position corresponding to the maximum frost area exposed to the emitted light i.e. air around the frost inside the frost layer. This position is defined as the frost layer position and it could give an effective frost layer.

  16. Interfacial Adhesion Study for Multi-Layer Structures with m-ELT Method and FEM Simulation

    NASA Astrophysics Data System (ADS)

    Hasunuma, Masahiko; Ito, Sachiyo; Kittaka, Hideyoshi

    2004-12-01

    The m-ELT method is widely used because of the simplicity. And the fracture mode of this method is similar to that of the actual TCT (Temperature Cycling Test) that is used for the reliability test of an LSI package. In this method, only the thermal stress that is stored in epoxy has been taken into consideration and the effects of very thin ILD layers have been ignored. In this study, we have considered a crack initiation state, so we have paid our attention to the thermal stress singularity field generated in the free edge of ILD in m-ELT measurement. We have evaluated the fracture toughness with two stress singularity parameters, lambda and Kf, in the tensile singular stress produced in ILDs' interface near the slit tip. And we have elucidated the effect of low-k film thickness and the effect of multiple-layer stacking modules that have plural identical interfaces by the m-ELT and FEM (finite element method) for the stress simulation. Especially the free-edge interface between SiOC and SiCN has been discussed, because this interface has lowest adhesion strength in this study. As a result, it has been derived that the low-k layer thickness has not affect stress singularity field. Moreover the Kapp estimated by the m-ELT has been affected by global layer (upper thick SiO2 layer) thickness. The stress relaxation caused by upper rigid layers makes the apparent value of Kapp increase. The stress concentration at the tip of a slit will change with ILD properties and detailed multi-layer structure. Therefore, in order to derive fracture toughness from the peeling temperature of the m-ELT method, it is the necessity of taking this change into consideration. Singularity parameters derived by a FEM simulation has been confirmed to be effective for deducing a fracture toughness criterion of an interface that has a stress singularity field.

  17. Anisotropic layers with through-thickness thermal and material variations

    SciTech Connect

    Ferrari, M. )

    1992-09-01

    The thermoelastic problem of an inhomogeneous anisotropic layer with material properties that vary smoothly through the thickness is examined. The problem is solved via a semiinverse technique, relying on the assumptions of the simply-connectedness of the body. The solution is applicable to the analysis of materials with chemical composition gradients and/or temperature-dependent material properties. 14 refs.

  18. Method of adhesion between an oxide layer and a metal layer

    DOEpatents

    Jennison, Dwight R.; Bogicevic, Alexander; Kelber, Jeffry A.; Chambers, Scott A.

    2004-09-14

    A method of controlling the wetting characteristics and increasing the adhesion between a metal and an oxide layer. By introducing a negatively-charged species to the surface of an oxide layer, layer-by-layer growth of metal deposited onto the oxide surface is promoted, increasing the adhesion strength of the metal-oxide interface. The negatively-charged species can either be deposited onto the oxide surface or a compound can be deposited that dissociates on, or reacts with, the surface to form the negatively-charged species. The deposited metal adatoms can thereby bond laterally to the negatively-charged species as well as vertically to the oxide surface as well as react with the negatively charged species, be oxidized, and incorporated on or into the surface of the oxide.

  19. Effects of interlayer thickness and the substrate material on the adhesion properties of CrZrN coatings

    NASA Astrophysics Data System (ADS)

    Kim, Kyu-Sung; Kim, Hoe-Kun; La, Joung-Hyun; Lee, Sang-Yul

    2016-01-01

    To confirm the influence of the interlayer thickness and substrate material on adhesion properties, CrZrN coatings with various Cr interlayer thickness were deposited on AISI H13, high speed steel, and tungsten carbide using unbalanced magnetron sputtering. The adhesion strength showed maximum value at 300 nm of the interlayer, but as the interlayer increased further to 450 nm, the adhesion strength decreased. The adhesion properties of the coatings were dependent upon not only interlayer thickness but also the substrate materials. The adhesion strength of the coating were measured 12, 32, 53 N on the tungsten carbide, AISI H13 steel, high speed steel, respectively and three different failure modes such as buckling spallation, wedging spallation, and chipping were observed on each substrate. The difference in adhesion properties could be attributed to the difference in value of elastic strain to failure (H/E) among the CrZrN coating, the interlayer, and the substrates material.

  20. Grafted polymers inside cylindrical tubes: Chain stretching vs layer thickness

    NASA Astrophysics Data System (ADS)

    Suo, Tongchuan; Whitmore, Mark D.

    2013-04-01

    We present a study of the detailed structure of grafted polymer chains and the layers they form inside cylindrical tubes, using the finitely extensible nonlinear elastic chain model and numerical self-consistent field theory. For very large tube radius, the chain stretching and layer thicknesses are the same as for polymers grafted to a planar surface. For decreasing radius, our calculations indicate that the layer almost always gets thinner, although there can be situations where it is very slightly thicker. However, we find that this thinning is not necessarily due to changes to the polymers: in fact, the root-mean-squared layer thickness would decrease even if the polymers themselves are completely unchanged. Furthermore, we find that the polymer stretching can increase at the same time that the layer thickness decreases. These apparent paradoxes are resolved by analyzing and distinguishing between the volume fraction profiles and monomer number distributions in these systems, including how they change and why. We also find that, in a given system, parts of each polymer move towards the curved surface and parts away from it, and that these differences are key to understanding the behavior.

  1. Mechanisms relating to reducing stress in curing thick sections of UV adhesives

    NASA Astrophysics Data System (ADS)

    Norland, Eric A.; Martin, Frank S.

    1993-09-01

    Ultraviolet curing adhesives are widely used in optical lamination of precision optical lenses, safety windows, holographic displays, and flat panel displays. In most of these applications they are being used in relatively thin films from 3 microns to 40 mils, because most formulations will only allow uv light to penetrate to a certain depth. If the formulation does cure in thicker sections, the stress due to shrinkage typically becomes a problem. U.V. adhesives have been developed which can be cured in relatively thick sections with minimum stress. In this paper, a number of formulations are compared for variations in stress when cured in thick sections and the conditions and mechanism to minimize stress are characterized.

  2. Retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in children with obesity

    PubMed Central

    Demir, Selim; Özer, Samet; Alim, Sait; Güneş, Alper; Ortak, Hüseyin; Yılmaz, Resul

    2016-01-01

    AIM To evaluate retinal nerve fiber layer (RNFL) thickness analysis of peripapillary optic nerve head (PONH) and macula as well as ganglion cell-inner plexiform layer (GCIPL) thickness in obese children. METHODS Eighty-five children with obesity and 30 controls were included in the study. The thicknesses of the PONH and macula of each subject's right eye were measured by high-resolution spectral-domain optic coherence tomography (OCT). RESULTS The RNFL thicknesses of central macular and PONH were similar between the groups (all P>0.05). The GCIPL thickness was also similar between the groups. However, the RNFL thickness of temporal outer macula were 261.7±13.7 and 268.9±14.3 µm for the obesity and the control group, respectively (P=0.034). CONCLUSION Obesity may cause a reduction in temporal outer macular RNFL thickness. PMID:27158616

  3. Adhesion and friction properties of polymer brushes: fluoro versus nonfluoro polymer brushes at varying thickness.

    PubMed

    Bhairamadgi, Nagendra S; Pujari, Sidharam P; Leermakers, Frans A M; van Rijn, Cees J M; Zuilhof, Han

    2014-03-01

    A series of different thicknesses of fluoro poly(2,2,2-trifluoroethyl methacrylate) and its analogous nonfluoro poly(ethyl methacrylate) polymer brushes were prepared via surface-initiated ATRP (SI-ATRP) on Si(111) surfaces. The thiol-yne click reaction was used to immobilize the SI-ATRP initiator with a high surface coverage, in order to achieve denser polymer brushes (grafting density from ~0.1 to 0.8 chains/nm(2)). All polymer brushes were characterized by static water contact angle measurements, infrared absorption reflection spectroscopy, and X-ray photoelectron spectroscopy. Adhesion and friction force measurements were conducted with silica colloidal probe atomic force microscopy (CP-AFM) under ambient and dry (argon) conditions. The fluoro poly(2,2,2-trifluoroethyl methacrylate) polymer showed a decrease in adhesion and friction with increasing thickness. The analogous nonfluoro poly(ethyl methacrylate) polymer brushes showed high adhesion and friction under ambient conditions. Friction coefficients down to 0.0057 (ambient conditions) and 0.0031 (dry argon) were obtained for poly(2,2,2-trifluoroethyl methacrylate) polymer brushes with 140 nm thickness, which are the lowest among these types of polymer brushes. PMID:24555721

  4. Development of hydrocolloid Bi-layer dressing with bio-adhesive and non-adhesive properties.

    PubMed

    Khan, M Iqbal H; Islam, Jahid M M; Kabir, Wasifa; Rahman, Ataur; Mizan, Maria; Rahman, M Fizur; Amin, Jakia; Khan, Mubarak A

    2016-12-01

    Bio-active bi-layer thin film having both bio-adhesive and non-adhesive end composed of polyvinyl alcohol (PVA) and gelatin/chitosan/polyethylene glycol (PEG) blend was developed for biomedical applications especially as an alternative of advanced tissue scaffold. The developed composite film was subjected to mechanical, thermal and physico-chemical characterization such as tensile strength (TS) and elongation at break (Eb), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), fluid drainage capacity and biocompatibility. Suitable packaging was also selected and stability study and aging test of the composite film were performed after packing. The incorporation of chitosan and PEG into gelatin showed improved mechanical properties of both TS and Eb, which suggested the occurrence of interaction among gelatin, chitosan and PEG molecules in the composite film. The presence of crosslinking as an interaction of above three polymers was also confirmed by FTIR study. Results from the DSC study suggested increased thermal stability after crosslinking. On the other hand, water uptake studies suggested excellent fluid drainage capability and hydro-stability of the composite film. The proposed dressing also showed excellent biocompatibility. Based on the studies related to the performance with confirmed identity, we concluded that our developed bi-layer film is very potential as an ideal wound dressing material. PMID:27612753

  5. Near independence of OLED operating voltage on transport layer thickness

    SciTech Connect

    Swensen, James S.; Wang, Liang; Polikarpov, Evgueni; Rainbolt, James E.; Koech, Phillip K.; Cosimbescu, Lelia; Padmaperuma, Asanga B.

    2013-01-01

    We report organic light emitting devices (OLEDs) with weak drive voltage dependence on the thickness of the hole transport layer (HTL) for thicknesses up to 1150 Å using the N,N′-Bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (α-NPD) and N,N'-bis(3-methyl phenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'diamine (TPD), both of which have hole mobilities in the range of 2 × 10-3 cm2V-1s-1. Lower mobility HTL materials show larger operating voltage dependence on thickness. The near independence of the operating voltage for high mobility transport material thickness was only observed when the energy barrier for charge injection into the transport material was minimized. To ensure low injection barriers, a thin film of 2-(3-(adamantan-1-yl)propyl)-3,5,6-trifluorotetracyanoquinodimethane (F3TCNQ-Adl) was cast from solution onto the ITO surface. These results indicate that thick transport layers can be integrated into OLED stacks without the need for bulk conductivity doping.

  6. Terahertz reflection interferometry for automobile paint layer thickness measurement

    NASA Astrophysics Data System (ADS)

    Rahman, Aunik; Tator, Kenneth; Rahman, Anis

    2015-05-01

    Non-destructive terahertz reflection interferometry offers many advantages for sub-surface inspection such as interrogation of hidden defects and measurement of layers' thicknesses. Here, we describe a terahertz reflection interferometry (TRI) technique for non-contact measurement of paint panels where the paint is comprised of different layers of primer, basecoat, topcoat and clearcoat. Terahertz interferograms were generated by reflection from different layers of paints on a metallic substrate. These interferograms' peak spacing arising from the delay-time response of respective layers, allow one to model the thicknesses of the constituent layers. Interferograms generated at different incident angles show that the interferograms are more pronounced at certain angles than others. This "optimum" angle is also a function of different paint and substrate combinations. An automated angular scanning algorithm helps visualizing the evolution of the interferograms as a function of incident angle and also enables the identification of optimum reflection angle for a given paint-substrate combination. Additionally, scanning at different points on a substrate reveals that there are observable variations from one point to another of the same sample over its entire surface area. This ability may be used as a quality control tool for in-situ inspection in a production line. Keywords: Terahertz reflective interferometry, Paint and coating layers, Non-destructive

  7. Compression response of thick layer composite laminates with through-the-thickness reinforcement

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Smith, Barry T.; Maiden, Janice

    1992-01-01

    Compression and compression-after-impact (CAI) tests were conducted on seven different AS4-3501-6 (0/90) 0.64-cm thick composite laminates. Four of the seven laminates had through-the-thickness (TTT) reinforcement fibers. Two TTT reinforcement methods, stitching and integral weaving, and two reinforcement fibers, Kevlar and carbon, were used. The remaining three laminates were made without TTT reinforcements and were tested to establish a baseline for comparison with the laminates having TTT reinforcement. Six of the seven laminates consisted of nine thick layers whereas the seventh material was composed of 46 thin plies. The use of thick-layer material has the potential for reducing structural part cost because of the reduced part count (layers of material). The compression strengths of the TTT reinforced laminates were approximately one half those of the materials without TTT reinforcements. However, the CAI strengths of the TTT reinforced materials were approximately twice those of materials without TTT reinforcements. The improvement in CAI strength is due to an increase in interlaminar strength produced by the TTT reinforcement. Stitched laminates had slightly higher compression and CAI strengths than the integrally woven laminates.

  8. Metalized nanotube tips improve through thickness thermal conductivity in adhesive joints.

    PubMed

    Ganguli, Sabyasachi; Sihn, Sangwook; Roy, Ajit K; Dai, Liming; Qu, Liangti

    2009-03-01

    The through-thickness thermal conductivity in conventional adhesive joints (of approximately 0.3 W/m-K) fails to meet the thermal load transfer requirement in numerous applications to enable lean manufacturing and improve system reliability to thermal load. Carbon nanotubes are known to possess extremely high thermal conductivity along the longitudinal axis. According to molecular dynamics simulations, the value can be as high as 3500 W/m-K at room temperature for multi-walled carbon nanotubes (MWCNT). Meanwhile, the transverse thermal conductivity perpendicular to the longitudinal axis of the MWCNTs is known to be relatively low, approximately 10-15 W/m-K. Existing studies of mixing the MWCNTs in polymers for adhesive joints only achieved minimal enhancement in the thermal conductivity and failed to satisfy the thermal property requirement for the adhesive joints. In order to properly utilize the superior axial thermal conductivity of the MWCNTs, vertically aligned MWCNTs have been used in this study and incorporated in the adhesive joint configuration. Analytical parametric study was conducted to identify critical parameters that affect the overall thermal conductivity of the joint and to provide guidelines for the process development. The process development involved growing the vertically aligned MWCNTs on silicon wafers. The aligned nanotube array was partially infused with epoxy adhesive. Selective reactive ion etching of the epoxy revealed the nanotube tips. In order to reduce the impedance mismatch and phonon scattering at the interface between the nanotube tips and the adherends, gold was thermally evaporated on the nanotube tips. The measured thermal conductivity of the adhesive joint device incorporating the MWCNTs was 262 W/m-K, which is significantly larger compared to that of less than 1 W/m-K without the MWCNTs. PMID:19435032

  9. Leidenfrost point and estimate of the vapour layer thickness

    NASA Astrophysics Data System (ADS)

    Gianino, Concetto

    2008-11-01

    In this article I describe an experiment involving the Leidenfrost phenomenon, which is the long lifetime of a water drop when it is deposited on a metal that is much hotter than the boiling point of water. The experiment was carried out with high-school students. The Leidenfrost point is measured and the heat laws are used to estimate the thickness of the vapour layer, d≈0.06 mm, which prevents the drop from touching the hotplate.

  10. Minimum Wind Dynamic Soaring Trajectories under Boundary Layer Thickness Limits

    NASA Astrophysics Data System (ADS)

    Bousquet, Gabriel; Triantafyllou, Michael; Slotine, Jean-Jacques

    2015-11-01

    Dynamic soaring is the flight technique where a glider, either avian or manmade, extracts its propulsive energy from the non-uniformity of horizontal winds. Albatrosses have been recorded to fly an impressive 5000 km/week at no energy cost of their own. In the sharp boundary layer limit, we show that the popular image, where the glider travels in a succession of half turns, is suboptimal for travel speed, airspeed, and soaring ability. Instead, we show that the strategy that maximizes the three criteria simultaneously is a succession of infinitely small arc-circles connecting transitions between the calm and windy layers. The model is consistent with the recordings of albatross flight patterns. This lowers the required wind speed for dynamic soaring by over 50% compared to previous beliefs. In the thick boundary layer limit, energetic considerations allow us to predict a minimum wind gradient necessary for sustained soaring consistent with numerical models.

  11. A study of the factors effecting layer thickness uniformity and layer breakup in microlayered coextruded films

    NASA Astrophysics Data System (ADS)

    Ghumman, Bhavjit Singh

    Microlayer coextrusion offers the opportunity to economically commercialize the production of nanometer thick film. A major obstacle towards commercialization is the non-uniform thickness of these layers and their breakup into droplets, which is also known as a scattering instability. Prior research had indicated a strong interaction between material properties and process parameters. Therefore, the focus of this research effort was to better understand and then identify the coextrusion parameters and material properties that governed the layer non-uniformity and scattering. Initial studies had indicated that there existed an interaction between the two extruders, which gave rise to pressure fluctuations and non-uniform flow. The interaction of the two extruders was studied by analyzing the pressure signals at the two extruders and the junction of the two streams. A response surface method was used to analyze the two extruders individually, the number of layer multiplying elements and finally the interaction between the two extruders and the effect they had on pressure, surging, flow rate and torque. Although the interaction of the two extruders did result in higher backpressures, it did not decrease the output. The output was independent of the screw speed of the other extruder, however it did influence the melting mechanics along the screw. The more shear sensitive PMMA showed a greater degree of sensitivity than the Newtonian PC. The influence of primary; coextrusion, and secondary; chill roll, processing on the final layer thickness was studied in a second set of experiments. For this purpose primary coextrusion process parameters such as screw speed ratio, die temperature and core melt temperature were changed and the effect on the layer thickness uniformity was studied. Similarly secondary process parameters such as nip gap and chill roll speed were also investigated. Thickness was measured using an Atomic Force Microscope (AFM). The screw speed ratio was the

  12. The effect of adhesive layer elasticity on the fracture mechanics of a blister test specimen

    NASA Technical Reports Server (NTRS)

    Updike, D. P.

    1975-01-01

    An analytical model of a blister type specimen for evaluating adhesive bond strength was developed. Plate theory with shear deformation was used to model the deformation of the plate, and elastic deformation of the adhesive layer is taken into account. It is shown that the inclusion of the elastic deformation of the adhesive layer can have a significant influence in the energy balance calculations of fracture mechanics.

  13. Usage of Neural Network to Predict Aluminium Oxide Layer Thickness

    PubMed Central

    Michal, Peter; Vagaská, Alena; Gombár, Miroslav; Kmec, Ján; Spišák, Emil; Kučerka, Daniel

    2015-01-01

    This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A·dm−2 and 3 A·dm−2 for creating aluminium oxide layer. PMID:25922850

  14. Neutron supermirrors: an accurate theory for layer thickness computation

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    2001-11-01

    We present a new theory for the computation of Super-Mirror stacks, using accurate formulas derived from the classical optics field. Approximations are introduced into the computation, but at a later stage than existing theories, providing a more rigorous treatment of the problem. The final result is a continuous thickness stack, whose properties can be determined at the outset of the design. We find that the well-known fourth power dependence of number of layers versus maximum angle is (of course) asymptotically correct. We find a formula giving directly the relation between desired reflectance, maximum angle, and number of layers (for a given pair of materials). Note: The author of this article, a classical opticist, has limited knowledge of the Neutron world, and begs forgiveness for any shortcomings, erroneous assumptions and/or misinterpretation of previous authors' work on the subject.

  15. Usage of neural network to predict aluminium oxide layer thickness.

    PubMed

    Michal, Peter; Vagaská, Alena; Gombár, Miroslav; Kmec, Ján; Spišák, Emil; Kučerka, Daniel

    2015-01-01

    This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A · dm(-2) and 3 A · dm(-2) for creating aluminium oxide layer. PMID:25922850

  16. Ultrasonic eggshell thickness measurement for selection of layers.

    PubMed

    Kibala, Lucyna; Rozempolska-Rucinska, Iwona; Kasperek, Kornel; Zieba, Grzegorz; Lukaszewicz, Marek

    2015-10-01

    This study aimed to develop a methodology for using ultrasonic technology (USG) to record eggshell thickness for selection of layers. Genetic correlations between eggshell strength and its thickness have been reported to be around 0.8, making shell thickness a selection index candidate element. Applying ultrasonic devices to measure shell thickness leaves an egg intact for further handling. In this study, eggs from 2 purebred populations of Rhode Island White (RIW) and Rhode Island Red (RIR) hens were collected on a single day in the 33rd week of the farm laying calendar from 2,414 RIR and 4,525 RIW hens. Beginning from the large end of the egg, measurements were taken at 5 latitudes: 0º (USG0), 45º (USG45), 90º (USG90), 135º (USG135), and 180º (USG180). To estimate the repeatability of readings, measurements were repeated at each parallel on 3 meridians. Electronic micrometer measurement ( EMM: ) were taken with an electronic micrometer predominantly at the wider end of eggs from 2,397 RIR and 4,447 RIW hens. A multiple-trait statistical model fit the fixed effect of year-of-hatch × hatch-within-year, and random effects due to repeated measurements (except EMM) and an animal's additive genetic component. The shell was thinnest in the region where chicks break it upon hatching (USG0, USG45). Heritabilities of shell thickness in different regions of the shell ranged from 0.09 to 0.19 (EMM) in RIW and from 0.12 to 0.23 (EMM) in RIR and were highest for USG45 and USG0. Because the measurement repeatabilities were all above 0.90, our recommendation for balancing egg strength against hatching ease is to take a single measurement of USG45. Due to high positive genetic correlations between shell thickness in different regions of the shell its thickness in the pointed end region will be modified accordingly, in response to selection for USG45. PMID:26316340

  17. Tracing the sub-photospheric layers of optically thick winds

    NASA Astrophysics Data System (ADS)

    Graefener, G.

    2013-06-01

    Towards the end of their evolution hot massive stars develop strong stellar winds and appear as emission line stars, such as WR stars or LBVs. The quanitative description of the mass loss in these important pre-SN phases is hampered by unkowns such as wind clumping and porosity, and by an incomplete theoretical understanding of optically thick stellar winds. Even the stellar radii in these phases are badly undestood as they are often variable (LBVs), or deviate from theoretical expectations (WR stars). Here we present a new semi-empirical method that helps to tackle these problems. By analysing a large sample of Galactic WR stars we gain information about deep wind layers near the sonic point which are otherwise not directly observable. We find evidence that these layers are clumped, with clumping factors comparable to the ones observed in the winds of WR stars. Moreover, density and temperature near the sonic point seem to follow a relation which is ubiqitous for optically thick winds, and which may be responsible for the peculiar radius properties of these objects.

  18. Measurement of Capsular Thickness in Magnetic Resonance Arthrography in Idiopathic Adhesive Capsulitis of Hip

    PubMed Central

    Joo, Young-Deuk; Sobti, Anshul Shyam

    2014-01-01

    Purpose The clinical suspicion of idiopathic adhesive capsulitis of the hip (IACH) involves restricted range of motion and normal hip radiographs. The purpose of this study was to delineate the characteristic findings observed on magnetic resonance arthrography (MRA) by identifying the anatomical structures involved and their significance on clinical presentation of restricted range of motion. Materials and Methods We retrospectively evaluated MRA's of 46 hips (44 patients) who suffered hip pain from September 2006 to August 2012 in our hospital. Of those, 10 cases (8 patients) with clinical suspicion of IACH were compared to 20 normal hip cases (control group). To identify anatomical evidence of adhesive capsulitis in the MRA's of the IACH group, capsular thickness was measured superiorly, inferiorly, anteriorly and posteriorly, and compared to that of the randomly selected control group. Results Comparison of the MRA findings of the control group to that of the IACH group showed that there was a statistically significant increase in the mean thickness of the joint capsule superiorly and posteriorly (P<0.01), while comparison of examination findings revealed a statistically significant decrease in the mean range of motion (flexion 122.5°±5.5°/abduction 28.0°±2.8°/adduction 26.5°±2.4°/external rotation 30.5°±3.8°/internal rotation 25.5°±2.4°) in the IACH group. Conclusion A change in the capsular thickness on MRA is a common finding in IACH patients with the increase more evident in the posterior and superior capsules than the anterior and inferior capsules.

  19. Effect of adherend thickness and mixed mode loading on debond growth in adhesively bonded composite joints

    NASA Technical Reports Server (NTRS)

    Mangalgiri, P. D.; Johnson, W. S.; Everett, R. A., Jr.

    1986-01-01

    Symmetric and unsymmetric double cantilever beam (DCB) specimens were tested and analyzed to assess the effect of: (1) adherend thickness, and (2) a predominantly mode I mixed mode loading on cyclic debond growth and static fracture toughness. The specimens were made of unidirectional composite (T300/5208) adherends bonded together with EC3445 structural adhesive. The thickness was 8, 16, or 24 plies. The experimental results indicated that the static fracture toughness increases and the cyclic debond growth rate decreases with increasing adherend thickness. This behavior was related to the length of the plastic zone ahead of the debond tip. For the symmetric DCB specimens, it was further found that displacement control tests resulted in higher debond growth rates than did load control tests. While the symmetric DCB tests always resulted in cohesive failures in the bondline, the unsymmetric DCB tests resulted in the debond growing into the thinner adherend and the damage progressing as delamination in that adherend. This behavior resulted in much lower fracture toughness and damage growth rates than found in the symmetric DCB tests.

  20. Reduced photoconductivity observed by time-resolved terahertz spectroscopy in metal nanofilms with and without adhesion layers

    NASA Astrophysics Data System (ADS)

    Alberding, Brian G.; Kushto, Gary P.; Lane, Paul A.; Heilweil, Edwin J.

    2016-05-01

    Non-contact, optical time-resolved terahertz spectroscopy has been used to study the transient photoconductivity of nanometer-scale metallic films deposited on the fused quartz substrates. Samples of 8 nm thick gold or titanium show an instrument-limited (ca. 0.5 ps) decrease in conductivity following photoexcitation due to electron-phonon coupling and subsequent increased lattice temperatures which increases charge carrier scattering. In contrast, for samples of 8 nm gold with a 4 nm adhesion layer of titanium or chromium, a ca. 70 ps rise time for the lattice temperature increase is observed. These results establish the increased transient terahertz transmission sign change of metallic compared to semiconductor materials. The results also suggest nanoscale gold films that utilize an adhesion material do not consist of distinct layers.

  1. a Spatio-Temporal Framework for Modeling Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Touyz, J.; Streletskiy, D. A.; Nelson, F. E.; Apanasovich, T. V.

    2015-07-01

    The Arctic is experiencing an unprecedented rate of environmental and climate change. The active layer (the uppermost layer of soil between the atmosphere and permafrost that freezes in winter and thaws in summer) is sensitive to both climatic and environmental changes, and plays an important role in the functioning, planning, and economic activities of Arctic human and natural ecosystems. This study develops a methodology for modeling and estimating spatial-temporal variations in active layer thickness (ALT) using data from several sites of the Circumpolar Active Layer Monitoring network, and demonstrates its use in spatial-temporal interpolation. The simplest model's stochastic component exhibits no spatial or spatio-temporal dependency and is referred to as the naïve model, against which we evaluate the performance of the other models, which assume that the stochastic component exhibits either spatial or spatio-temporal dependency. The methods used to fit the models are then discussed, along with point forecasting. We compare the predicted fit of the various models at key study sites located in the North Slope of Alaska and demonstrate the advantages of space-time models through a series of error statistics such as mean squared error, mean absolute and percent deviance from observed data. We find the difference in performance between the spatio-temporal and remaining models is significant for all three error statistics. The best stochastic spatio-temporal model increases predictive accuracy, compared to the naïve model, of 33.3%, 36.2% and 32.5% on average across the three error metrics at the key sites for a one-year hold out period.

  2. Accretion disk boundary layers in cataclysmic variables. 1: Optically thick boundary layers

    NASA Technical Reports Server (NTRS)

    Popham, Robert; Narayan, Ramesh

    1995-01-01

    We develop numerical models of accretions disks in cataclysmic variables (CVs), including and emphasizing the boundary layer region where the accretion disk meets the accreting white dwarf. We confine ourselves to solutions where the boundary layer region is vertically optically thick, and find that these solutions share several common features. The angular and radial velocities of the accreting material drop rapidly in a dynamical boundary layer, which has a radial width approximately 1%-3% of the white dwarf radius. The energy dissipated in this region diffuses through the inner part of the disk and is radiated from the disk surface in a thermal boundary layer, which has a radial width comparable to the disk thickness, approximately 5%-15% of the white dwarf radius. We examine the dependence of the boundary layer structure on the mass accretion rate, the white dwarf mass and rotation rate, and the viscosity parameter alpha. We delineate the boundary between optically thick and optically thin boundary layer solutions as a function of these parameters and suggest that by means of a careful comparison with observations it may be possible to estimate alpha in CVs. We derive an expression for the total boundary layer luminosities as a function of the parameters and show that it agrees well with the luminosites of our numerical solutions. Finally, we calcuate simple blackbody continuum spectra of the boundary layer and disk emission for our solutions and compare these to soft X-ray, EUV, and He II emission-line observations of CVs. We show that, through such comparisons, it may be possible to determine the rotation rates of the accreting stars in CVs, and perhaps also the white dwarf masses and the accretion rates. The spectra are quite insensitive to alpha, so the uncertainty in this parameter does not affect such comparisons.

  3. Thickness-induced structural phase transformation of layered gallium telluride.

    PubMed

    Zhao, Q; Wang, T; Miao, Y; Ma, F; Xie, Y; Ma, X; Gu, Y; Li, J; He, J; Chen, B; Xi, S; Xu, L; Zhen, H; Yin, Z; Li, J; Ren, J; Jie, W

    2016-07-28

    The thickness-dependent electronic states and physical properties of two-dimensional materials suggest great potential applications in electronic and optoelectronic devices. However, the enhanced surface effect in ultra-thin materials might significantly influence the structural stability, as well as the device reliability. Here, we report a spontaneous phase transformation of gallium telluride (GaTe) that occurred when the bulk was exfoliated to a few layers. Transmission electron microscopy (TEM) results indicate a structural variation from a monoclinic to a hexagonal structure. Raman spectra suggest a critical thickness for the structural transformation. First-principle calculations and thermodynamic analysis show that the surface energy and the interlayer interaction compete to dominate structural stability in the thinning process. A two-stage transformation process from monoclinic (m) to tetragonal (T) and then from tetragonal to hexagonal (h) is proposed to understand the phase transformation. The results demonstrate the crucial role of interlayer interactions in the structural stability, which provides a phase engineering strategy for device applications. PMID:27198938

  4. Cross-linked Bioreducible Layer-by-layer Films for Increased Cell Adhesion and Transgene Expression

    PubMed Central

    Blacklock, Jenifer; Sievers, Torsten K.; Handa, Hitesh; You, Ye-Zi; Oupický, David; Mao, Guangzhao; Möhwald, Helmuth

    2010-01-01

    The effect of cross-linking layer-by-layer (LbL) films consisting of bioreducible poly(2-dimethylaminoethyl methacrylate) (rPDMAEMA) and DNA is examined with regards to rigidity, biodegradability, cell adhesion, and transfection activity using 1,5-diiodopentane (DIP) cross-linker. DIP chemically reacts with the tertiary amines of rPDMAEMA, altering the chemical composition of these LbL films. The result is a change in surface morphology, film swelling behavior and film rigidity, measured with AFM and ellipsometry. It is found that the apparent Young’s modulus is increased more than four times its original value upon cross-linking. Cross-linking mass is additionally confirmed with quartz crystal microbalance with dissipation (QCM-D). Comprehensive analyses of these experimental values were investigated to calculate the degree of cross-linking using the rubber elasticity theory and the Flory-Rehner theory. Additionally, the Flory-Huggins parameter, χ, was calculated. Good agreement in the two methods yields a cross-linking density of ~0.82 mmol/cm3. The Flory-Huggins parameter increased upon cross-linking from 1.07 to 1.2, indicating increased hydrophobicity of the network and formation of bulk water droplets within the films. In addition, the effects of cross-linking on film disassembly by 1,4-dithiothreitol (DTT) is found to be insignificant despite the alteration in film rigidity. Mouse fibroblast cells and smooth muscle cells are used to study the effect of cross-linking on cell adhesion and cell transfection activity. In vitro transfection activity up to seven days is quantified using secreted alkaline phosphatase (SEAP) DNA. Film cross-linking is found to enhance cell adhesion and prolong the duration of cellular transfection. These results contribute to the development of bioreducible polymer coatings for localized gene delivery. PMID:20369813

  5. Dependence of Gold Nanoparticle Radiosensitization on Functionalizing Layer Thickness.

    PubMed

    Spaas, Cedric; Dok, Rüveyda; Deschaume, Olivier; De Roo, Bert; Vervaele, Mattias; Seo, Jin Won; Bartic, Carmen; Hoet, Peter; Van den Heuvel, Frank; Nuyts, Sandra; Locquet, Jean-Pierre

    2016-04-01

    Gold nanoparticles functionalized with polyethylene glycol of different chain lengths are used to determine the influence of the capping layer thickness on the radiosensitizing effect of the particles. The size variations in organic coating, built up with polyethylene glycol polymers of molecular weight 1-20 kDa, allow an evaluation of the decrease in dose enhancement percentages caused by the gold nanoparticles at different radial distances from their surface. With localized eradication of malignant cells as a primary focus, radiosensitization is most effective after internalization in the nucleus. For this reason, we performed controlled radiation experiments, with doses up to 20 Gy and particle diameters in a range of 5-30 nm, and studied the relaxation pattern of supercoiled DNA. Subsequent gel electrophoresis of the suspensions was performed to evaluate the molecular damage and consecutively quantify the gold nanoparticle sensitization. In conclusion, on average up to 58.4% of the radiosensitizing efficiency was lost when the radial dimensions of the functionalizing layer were increased from 4.1 to 15.3 nm. These results serve as an experimental supplement for biophysical simulations and demonstrate the influence of an important parameter in the development of nanomaterials for targeted therapies in cancer radiotherapy. PMID:26950059

  6. Multi-layer electrospun membrane mimicking tendon sheath for prevention of tendon adhesions.

    PubMed

    Jiang, Shichao; Yan, Hede; Fan, Dapeng; Song, Jialin; Fan, Cunyi

    2015-01-01

    Defect of the tendon sheath after tendon injury is a main reason for tendon adhesions, but it is a daunting challenge for the biomimetic substitute of the tendon sheath after injury due to its multi-layer membrane-like structure and complex biologic functions. In this study, a multi-layer membrane with celecoxib-loaded poly(l-lactic acid)-polyethylene glycol (PELA) electrospun fibrous membrane as the outer layer, hyaluronic acid (HA) gel as middle layer, and PELA electrospun fibrous membrane as the inner layer was designed. The anti-adhesion efficacy of this multi-layer membrane was compared with a single-layer use in rabbit flexor digitorum profundus tendon model. The surface morphology showed that both PELA fibers and celecoxib-loaded PELA fibers in multi-layer membrane were uniform in size, randomly arrayed, very porous, and smooth without beads. Multi-layer membrane group had fewer peritendinous adhesions and better gliding than the PELA membrane group and control group in gross and histological observation. The similar mechanical characteristic and collagen expression of tendon repair site in the three groups indicated that the multi-layer membrane did not impair tendon healing. Taken together, our results demonstrated that such a biomimetic multi-layer sheath could be used as a potential strategy in clinics for promoting tendon gliding and preventing adhesion without poor tendon healing. PMID:25822877

  7. Robust adhesion of flower-like few-layer graphene nanoclusters

    PubMed Central

    Tian, Shibing; Li, Lin; Sun, Wangning; Xia, Xiaoxiang; Han, Dong; Li, Junjie; Gu, Changzhi

    2012-01-01

    Nanostructured surface possessing ultrahigh adhesion like “gecko foot” or “rose petal” can offer more opportunities for bionic application. We grow flower-like few-layer graphene on silicon nanocone arrays to form graphene nanoclusters, showing robust adhesion. Their contact angle (CA) is 164° with a hysteresis CA of 155° and adhesive force for a 5 μL water droplet is about 254 μN that is far larger than present reported results. We bring experimental evidences that this great adhesion depends on large-area plentiful edges of graphene nanosheets tuned by conical nanostructure and intrinsic wetting features of graphene. Such new hierarchical few-layer graphene nanostructure provides a feasible strategy to understand the ultra-adhesive mechanism of the “gecko effect” or “rose effect” and enhance the wettability of graphene for many practical applications. PMID:22803004

  8. Robust adhesion of flower-like few-layer graphene nanoclusters

    NASA Astrophysics Data System (ADS)

    Tian, Shibing; Li, Lin; Sun, Wangning; Xia, Xiaoxiang; Han, Dong; Li, Junjie; Gu, Changzhi

    2012-07-01

    Nanostructured surface possessing ultrahigh adhesion like ``gecko foot'' or ``rose petal'' can offer more opportunities for bionic application. We grow flower-like few-layer graphene on silicon nanocone arrays to form graphene nanoclusters, showing robust adhesion. Their contact angle (CA) is 164° with a hysteresis CA of 155° and adhesive force for a 5 μL water droplet is about 254 μN that is far larger than present reported results. We bring experimental evidences that this great adhesion depends on large-area plentiful edges of graphene nanosheets tuned by conical nanostructure and intrinsic wetting features of graphene. Such new hierarchical few-layer graphene nanostructure provides a feasible strategy to understand the ultra-adhesive mechanism of the ``gecko effect'' or ``rose effect'' and enhance the wettability of graphene for many practical applications.

  9. Robust adhesion of flower-like few-layer graphene nanoclusters.

    PubMed

    Tian, Shibing; Li, Lin; Sun, Wangning; Xia, Xiaoxiang; Han, Dong; Li, Junjie; Gu, Changzhi

    2012-01-01

    Nanostructured surface possessing ultrahigh adhesion like "gecko foot" or "rose petal" can offer more opportunities for bionic application. We grow flower-like few-layer graphene on silicon nanocone arrays to form graphene nanoclusters, showing robust adhesion. Their contact angle (CA) is 164° with a hysteresis CA of 155° and adhesive force for a 5 μL water droplet is about 254 μN that is far larger than present reported results. We bring experimental evidences that this great adhesion depends on large-area plentiful edges of graphene nanosheets tuned by conical nanostructure and intrinsic wetting features of graphene. Such new hierarchical few-layer graphene nanostructure provides a feasible strategy to understand the ultra-adhesive mechanism of the "gecko effect" or "rose effect" and enhance the wettability of graphene for many practical applications. PMID:22803004

  10. Adhesion

    MedlinePlus

    ... adhesions Ovarian cyst References Munireddy S, Kavalukas SL, Barbul A. Intra-abdominal healing: gastrointestinal tract and adhesions. Surg Clin N Am Kulaylat MN, Dayton, MT. Surgical complications. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, ...

  11. Determination of layer-thickness variation in periodic multilayer by x-ray reflectivity

    SciTech Connect

    Jiang Hui; Zhu Jingtao; Xu Jing; Wang Xiaoqiang; Wang Zhanshan; Watanabe, Makoto

    2010-05-15

    A method basically determining individual layer thicknesses in actual periodic multilayers has been developed, that solves simultaneous equations of positions of peaks appearing in wavelet transform curve of x-ray grazing incidence reflectivity. The determination was demonstrated on a Ni/C periodic multilayer fabricated by magnetron sputtering. Using the layer thicknesses obtained by the method, further accurate of thickness, roughness, and density of each layer was performed by Parratt's model. The special feature that the topmost and bottom-most layers were thicker than other layers was clearly observed. The former is attributed to oxidation and the latter is attributed to the effect of deposition on thick substrate. The mean fluctuations of other layers are 2.6% in C layers and 4.2% in Ni layers attributed to random fluctuations at deposition. Numerical analysis and statistical hypothesis tests have been carried out to discuss noncumulative and cumulative layer-thickness fluctuations in fabrication process.

  12. Computational Study of Surface Tension and Wall Adhesion Effects on an Oil Film Flow Underneath an Air Boundary Layer

    NASA Technical Reports Server (NTRS)

    Celic, Alan; Zilliac, Gregory G.

    1998-01-01

    The fringe-imaging skin friction (FISF) technique, which was originally developed by D. J. Monson and G. G. Mateer at Ames Research Center and recently extended to 3-D flows, is the most accurate skin friction measurement technique currently available. The principle of this technique is that the skin friction at a point on an aerodynamic surface can be determined by measuring the time-rate-of-change of the thickness of an oil drop placed on the surface under the influence of the external air boundary layer. Lubrication theory is used to relate the oil-patch thickness variation to shear stress. The uncertainty of FISF measurements is estimated to be as low as 4 percent, yet little is known about the effects of surface tension and wall adhesion forces on the measured results. A modified version of the free-surface Navier-Stokes solver RIPPLE, developed at Los Alamos National Laboratories, was used to compute the time development of an oil drop on a surface under a simulated air boundary layer. RIPPLE uses the volume of fluid method to track the surface and the continuum surface force approach to model surface tension and wall adhesion effects. The development of an oil drop, over a time period of approximately 4 seconds, was studied. Under the influence of shear imposed by an air boundary layer, the computed profile of the drop rapidly changes from its initial circular-arc shape to a wedge-like shape. Comparison of the time-varying oil-thickness distributions computed using RIPPLE and also computed using a greatly simplified numerical model of an oil drop equation which does not include surface tension and wall adhesion effects) was used to evaluate the effects of surface tension on FISF measurement results. The effects of surface tension were found to be small but not necessarily negligible in some cases.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Composite Fermion Spin Polarization Energy with Finite Layer Thickness

    NASA Astrophysics Data System (ADS)

    Shayegan, Mansour; Liu, Yang; Hasdemir, Sukret; Pfeiffer, Loren; West, Ken; Baldwin, Kirk

    2014-03-01

    We study the spin polarization transitions of fractional quantum Hall (FQH) states in the filling range 1 < ν < 2 in symmetric quantum wells (QWs), as a function of density. Our results reveal a strong well-width dependence of the critical density nC and ratio between the Zeeman energy (EZ) normalized to the Coulomb energy (e2 / 4 πɛlB), above which a certain FQH state becomes spin polarized. For example, the ν = 7 / 5 FQH state becomes spin polarized at about 3 times higher density or 1.7 times larger EZ in the 31-nm-wide QW than in the 65-nm-wide QW. This well-width dependence of the spin polarization stems from by the finite electron layer thickness in these QWs and the resulting softening of the Coulomb interaction. We acknowledge support through the DOE BES (DE-FG02-00-ER45841) for measurements, and the Gordon and Betty Moore Foundation (Grant GBMF2719), Keck Foundation, and the NSF (DMR-0904117, DMR-1305691 and MRSEC DMR-0819860) for sample fabrication. Work at Arg.

  15. Towards NOAA Forecasts of Permafrost Active Layer Thickness

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Diffusion barrier and adhesion properties of SiO(x)N(y) and SiO(x) layers between Ag/polypyrrole composites and Si substrates.

    PubMed

    Horváth, Barbara; Kawakita, Jin; Chikyow, Toyohiro

    2014-06-25

    This paper describes the interface reactions and diffusion between silver/polypyrrole (Ag/PPy) composite and silicon substrate. This composite material can be used as a novel technique for 3D-LSI (large-scale integration) by the fast infilling of through-silicon vias (TSV). By immersion of the silicon wafer with via holes into the dispersed solution of Ag/PPy composite, the holes are filled with the composite. It is important to develop a layer between the composite and the Si substrate with good diffusion barrier and adhesion characteristics. In this paper, SiOx and two types of SiOxNy barrier layers with various thicknesses were investigated. The interface structure between the Si substrate, the barrier, and the Ag/PPy composite was characterized by transmission electron microscopy. The adhesion and diffusion properties of the layers were established for Ag/PPy composite. Increasing thickness of SiOx proved to permit less Ag to transport into the Si substrate. SiOxNy barrier layers showed very good diffusion barrier characteristics; however, their adhesion depended strongly on their composition. A barrier layer composition with good adhesion and Ag barrier properties has been identified in this paper. These results are useful for filling conductive metal/polymer composites into TSV. PMID:24869419

  17. Indium-gallium-zinc-oxide layer used to increase light transmittance efficiency of adhesive layer for stacked-type multijunction solar cells

    NASA Astrophysics Data System (ADS)

    Yoshidomi, Shinya; Kimura, Shunsuke; Hasumi, Masahiko; Sameshima, Toshiyuki

    2015-11-01

    We report the increase in transmittance efficiency of the intermediate layer for multijunction solar cells caused by the indium-gallium-zinc-oxide (IGZO) layer used as the antireflection layer. Si substrates coated with a 200-nm-thick IGZO layer with a refractive index of 1.85 were prepared. The resistivity of the IGZO layer was increased from 0.0069 (as-deposited) to 0.032 Ω cm by heat treatment at 350 °C for 1 h to prevent free-carrier optical absorption. Samples with the Si/IGZO/adhesive/IGZO/Si structure were fabricated. The average transmissivity for wavelengths between 1200 and 1600 nm was 49%, which was close to 55% of single-crystal silicon substrates. A high effective transmittance efficiency of 89% was experimentally achieved. The numerical calculation showed in an effective transmittance efficiency of 99% for 170-nm-thick antireflection layers with a resistivity of 0.6 Ω cm and a refractive index of 2.1.

  18. Thickness of the Meniscal Lamellar Layer: Correlation with Indentation Stiffness and Comparison of Normal and Abnormally Thick Layers by Using Multiparametric Ultrashort Echo Time MR Imaging.

    PubMed

    Choi, Ja-Young; Biswas, Reni; Bae, Won C; Healey, Robert; Im, Michael; Statum, Sheronda; Chang, Eric Y; Du, Jiang; Bydder, Graeme M; D'Lima, Darryl; Chung, Christine B

    2016-07-01

    Purpose To determine the relationship between lamellar layer thickness on ultrashort echo time (UTE) magnetic resonance (MR) images and indentation stiffness of human menisci and to compare quantitative MR imaging values between two groups with normal and abnormally thick lamellar layers. Materials and Methods This was a HIPAA-compliant, institutional review board-approved study. Nine meniscal pieces were obtained from seven donors without gross meniscal pathologic results (mean age, 57.4 years ± 14.5 [standard deviation]). UTE MR imaging and T2, UTE T2*, and UTE T1ρ mapping were performed. The presence of abnormal lamellar layer thickening was determined and thicknesses were measured. Indentation testing was performed. Correlation between the thickness and indentation stiffness was assessed, and mean quantitative MR imaging values were compared between the groups. Results Thirteen normal lamellar layers had mean thickness of 232 μm ± 85 and indentation peak force of 1.37 g ± 0.87. Four abnormally thick lamellar layers showed mean thickness of 353.14 μm ± 98.36 and peak force 0.72 g ± 0.31. In most cases, normal thicknesses showed highly positive correlation with the indentation peak force (r = 0.493-0.912; P < .001 to .05). However, the thickness in two abnormal lamellar layers showed highly negative correlation (r = -0.90, P < .001; and r = -0.23, P = .042) and no significant correlation in the others. T2, UTE T2*, and UTE T1ρ values in abnormally thick lamellar layers were increased compared with values in normal lamellar layers, although only the UTE T2* value showed significant difference (P = .010). Conclusion Variation of lamellar layer thickness in normal human menisci was evident on two-dimensional UTE images. In normal lamellar layers, thickness is highly and positively correlated with surface indentation stiffness. UTE T2* values may be used to differentiate between normal and abnormally thickened lamellar layers. (©) RSNA, 2016. PMID:26829523

  19. Obtaining Thickness Maps of Corneal Layers Using the Optimal Algorithm for Intracorneal Layer Segmentation

    PubMed Central

    Rabbani, Hossein; Kazemian Jahromi, Mahdi; Jorjandi, Sahar; Mehri Dehnavi, Alireza; Hajizadeh, Fedra; Peyman, Alireza

    2016-01-01

    Optical Coherence Tomography (OCT) is one of the most informative methodologies in ophthalmology and provides cross sectional images from anterior and posterior segments of the eye. Corneal diseases can be diagnosed by these images and corneal thickness maps can also assist in the treatment and diagnosis. The need for automatic segmentation of cross sectional images is inevitable since manual segmentation is time consuming and imprecise. In this paper, segmentation methods such as Gaussian Mixture Model (GMM), Graph Cut, and Level Set are used for automatic segmentation of three clinically important corneal layer boundaries on OCT images. Using the segmentation of the boundaries in three-dimensional corneal data, we obtained thickness maps of the layers which are created by these borders. Mean and standard deviation of the thickness values for normal subjects in epithelial, stromal, and whole cornea are calculated in central, superior, inferior, nasal, and temporal zones (centered on the center of pupil). To evaluate our approach, the automatic boundary results are compared with the boundaries segmented manually by two corneal specialists. The quantitative results show that GMM method segments the desired boundaries with the best accuracy. PMID:27247559

  20. Near-infrared chemical imaging used for in-line analysis of inside adhesive layers in textile laminates.

    PubMed

    Mirschel, Gabriele; Daikos, Olesya; Scherzer, Tom; Steckert, Carsten

    2016-08-17

    This paper demonstrates for the first time that near-infrared (NIR) chemical imaging can be used for in-line analysis of textile lamination processes. In particular, it was applied for the quantitative determination of the applied coating weight and for monitoring of the spatial distribution of hot melt adhesive layers using chemometric approaches for spectra evaluation. Layers with coating weights between about 25 and 130 g m(-2) were used for the lamination of polyester fabrics and nonwovens as well as for polyurethane foam. It was shown that quantitative data with adequate precision can be actually obtained for layers applied to materials with significantly heterogeneous surface structure such as foam or for hidden layers inside fabric laminates. Even the coating weight and the homogeneity of adhesive layers in composites consisting of black textiles only could be quantitatively analyzed. The prediction errors (RMSEP) determined in an external validation of each calibration model were found to range from about 2 g m(-2) to 6 g m(-2) depending on the specific system under investigation. All calibration models were applied for chemical imaging in order to prove their performance for monitoring the thickness and the homogeneity of adhesive layers in the various textile systems. Moreover, they were used for the detection of irregularities and coating defects. Investigations were carried out with a large hyperspectral camera mounted above a conveyor. Therefore, this method allows large-area monitoring of the properties of laminar materials. Consequently, it is potentially suited for process and quality control during the lamination of fabrics, foams and other materials in field-scale. PMID:27286771

  1. Quantitative analysis of adhesive resin in the hybrid layer using Raman spectroscopy

    PubMed Central

    Zou, Yuan; Armstrong, Steven R.; Jessop, Julie L. P.

    2009-01-01

    The objective was to determine absolute molar concentration of adhesive resin components in the hybrid layer by establishing methods based on Raman spectroscopy fundamentals. The hybrid layer was treated as a three-component system consisting of collagen and an adhesive resin containing two monomers. Adhesive standard specimens and Raman peak area ratios obtained with a 785 nm excitation wavelength were used to construct separate calibration curves for comonomer relative molar concentration and Bis-GMA absolute molar concentration. Since collagen and water had no measurable peaks in the fingerprint region, a dilution coefficient Kj was defined to describe their impact on Raman peak area and to calculate HEMA absolute molar concentration. Methodology was validated using an analogous system containing acetone/ethanol/water. The absolute molar concentration of Bis-GMA and HEMA decreased 87% and 83%, respectively, from the top quarter to the middle of the hybrid layer. Additionally, less Bis-GMA penetrated the hybrid layer than HEMA, as indicated by the ∼20% decrease in comonomer molar concentration ratio between the adhesive resin layer and the top half of the hybrid layer. Lack of complete monomer infiltration will further challenge dentin-adhesive bond longevity. PMID:20186729

  2. Multi-pane glass unit having seal with adhesive and hermetic coating layer

    SciTech Connect

    Miller, Seth A; Stark, David H; Francis, IV, William H; Puligandla, Viswanadham; Boulos, Edward N; Pernicka, John

    2015-02-10

    A vacuum insulated glass unit (VIGU) comprises a first pane of a transparent material and a second pane of a transparent material. The second pane is spaced apart from the first pane to define a cavity therebetween. At least one of a spacer and an array of stand-off members is disposed between the first and second panes to maintain separation therebetween. A first adhesive layer forms at least a portion of a gas-tight connection between the first pane and the second pane. A highly hermetic coating is disposed over the adhesive layer, where the coating is an inorganic layer.

  3. A Study on the Adhesion Properties of Reactive Sputtered Molybdenum Thin Films with Nitrogen Gas on Polyimide Substrate as a Cu Barrier Layer.

    PubMed

    Kim, Hong Sik; Kim, Byoung O; Seo, Jong Hyun

    2015-11-01

    NiCr, Mo, and Mo-N thin copper diffusion barrier films are deposited on 200 um thick polyimide films spin-coated on glass substrates by dc reactive magnetron sputtering. The adhesion forces for three systems are measured by micro-scratch test analysis depending on oxygen plasma pretreatment, sputtering power density, moisture contents, and post annealing treatment. The values of adhesion forces for the three systems are linearly proportional to the oxygen plasma treatment time. As deposition power density increases, measured adhesion forces also increase. The existence of moisture adsorbed in the polymer substrate prior to initiating the sputtering process significantly reduces the adhesion force for all systems. Post annealing treatment at 150 degrees C for 12 hours after sputtering also deteriorates the adhesion between the barrier films and polymer substrate. Auger electron spectroscopy reveals that adhesion forces are significantly dependent on the types of compounds formed at the barrier layer/polymer interface. Changes in the adhesion properties of the MoN system as a function of the nitrogen content are explained in terms of the mechanical stability of the MoN(x)O(y) interface layer on the polymer substrate. PMID:26726588

  4. Layer-by-layer Assembly of Thick, Cu2+-Chelating Films

    PubMed Central

    Wijeratne, Salinda; Bruening, Merlin L.; Baker, Gregory L.

    2013-01-01

    Layer-by-layer adsorption of protonated poly(allylamine) (PAH) and deprotonated poly(N,N-dicarboxymethylallyl amine) (PDCMAA) yields thick films with a high density of iminodiacetic acid (IDA) ligands that bind metal ions. When film deposition occurs at pH 3.0, PAH/PDCMAA bilayer thicknesses reach 200 nm, and Cu2+ binding capacities are ~2.5 mmoles per cm3 of film. (PAH/PDCMAA)10 films deposited at pH 3.0 are 4- to 8-fold thicker than films formed at pH 5.0, 7.0, or 9.0, presumably because of the low charge density on PDCMAA chains at pH 3.0. However, with normalization to film thickness, all films bind similar amounts of Cu2+ from pH 4.1 solutions of CuSO4. In μm-thick films, equilibration of binding sites with Cu2+ requires ~4 h due to a low Cu2+ diffusion coefficient (~2.6×10−12 cm2/sec). Sorption isotherms determined at several temperatures show that Cu2+ binding is endothermic with a positive entropy (binding constants increase with increasing temperature), presumably because metal-ion complexation involves displacement of both a proton from IDA and water molecules from Cu2+. (PAH/PDCMAA)10 films retain their binding capacity over 4 absorption/elution cycles and may prove useful in metal-ion scavenging, catalysis, and protein binding. PMID:24044576

  5. Inversion of thicknesses of multi-layered structures from eddy current testing measurements.

    PubMed

    Huang, Ping-jie; Wu, Zhao-tong

    2004-01-01

    Luquire et al.'s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-layered structures in terms of eddy current testing voltage measurements. An experimental system for multi-layered thickness measurement was developed and several fitting models to formulate the relationships between detected impedance/voltage measurements and thickness are put forward using least square method. The determination of multi-layered thicknesses was investigated after inversing the voltage outputs of the detecting system. The best fitting and inversion models are presented. PMID:14663858

  6. Effects of ultrasonic agitation on adhesion strength of micro electroforming Ni layer on Cu substrate.

    PubMed

    Zhao, Zhong; Du, Liqun; Xu, Zheng; Shao, Ligeng

    2016-03-01

    Micro electroforming is an important technology, which is widely used for fabricating micro metal devices in MEMS. The micro metal devices have the problem of poor adhesion strength, which has dramatically influenced the dimensional accuracy of the devices and seriously limited the development of the micro electroforming technology. In order to improve the adhesion strength, ultrasonic agitation method is applied during the micro electroforming process in this paper. To explore the effect of the ultrasonic agitation, micro electroforming experiments were carried out under ultrasonic and ultrasonic-free conditions. The effects of the ultrasonic agitation on the micro electroforming process were investigated by polarization and alternating current (a.c.) impedance methods. The real surface area of the electroforming layer was measured by cyclic voltammetry method. The compressive stress and the crystallite size of the electroforming layer were measured by X-ray Diffraction (XRD) method. The adhesion strength of the electroforming layer was measured by scratch test. The experimental results show that the imposition of the ultrasonic agitation decreases the polarization overpotential and increases the charge transfer process at the electrode-electrolyte interface during the electroforming process. The ultrasonic agitation increases the crystallite size and the real surface area, and reduces the compressive stress. Then the adhesion strength is improved about 47% by the ultrasonic agitation in average. In addition, mechanisms of the ultrasonic agitation improving the adhesion strength are originally explored in this paper. The mechanisms are that the ultrasonic agitation increases the crystallite size, which reduces the compressive stress. The lower the compressive stress is, the larger the adhesion strength is. Furthermore, the ultrasonic agitation increases the real surface area, enhances the mechanical interlocking strength and consequently increases the adhesion

  7. Retinal nerve fiber layer thickness and retinal vessel calibers in children with thalassemia minor

    PubMed Central

    Acer, Semra; Balcı, Yasemin I; Pekel, Gökhan; Ongun, Tuğba T; Polat, Aziz; Çetin, Ebru N; Yağcı, Ramazan

    2016-01-01

    Objectives: Evaluation of the peripapillary retinal nerve fiber layer thickness, subfoveal choroidal thickness, and retinal vessel caliber measurements in children with thalassemia minor. Methods: In this cross-sectional and comparative study, 30 thalassemia minor patients and 36 controls were included. Heidelberg spectral domain optical coherence tomography was used for peripapillary retinal nerve fiber layer thickness, subfoveal choroidal thickness, and retinal vessel caliber measurements. Results: There was no statistically significant difference in retinal nerve fiber layer thickness and subfoveal choroidal thickness between the two groups (p > 0.05). There was no correlation between retinal nerve fiber layer thickness and hemoglobin values. Both the arterioral and venular calibers were higher in thalassemia minor group (p < 0.05). Conclusion: There is increased retinal arterioral and venular calibers in children with thalassemia minor compared with controls. PMID:27540484

  8. Adhesion force measurements on the two wax layers of the waxy zone in Nepenthes alata pitchers

    PubMed Central

    Gorb, Elena V.; Purtov, Julia; Gorb, Stanislav N.

    2014-01-01

    The wax coverage of the waxy zone in Nepenthes alata pitchers consists of two clearly distinguishable layers, designated the upper and lower wax layers. Since these layers were reported to reduce insect attachment, they were considered to have anti-adhesive properties. However, no reliable adhesion tests have been performed with these wax layers. In this study, pull-off force measurements were carried out on both wax layers of the N. alata pitcher and on two reference polymer surfaces using deformable polydimethylsiloxane half-spheres as probes. To explain the results obtained, roughness measurements were performed on test surfaces. Micro-morphology of both surface samples and probes tested was examined before and after experiments. Pull-off forces measured on the upper wax layer were the lowest among surfaces tested. Here, contamination of probes by wax crystals detached from the pitcher surface was found. This suggests that low insect attachment on the upper wax layer is caused primarily by the breaking off of wax crystals from the upper wax layer, which acts as a separation layer between the insect pad and the pitcher surface. High adhesion forces obtained on the lower wax layer are explained by the high deformability of probes and the particular roughness of the substrate. PMID:24889352

  9. Thickness Mapping of Eleven Retinal Layers Segmented Using the Diffusion Maps Method in Normal Eyes

    PubMed Central

    Kafieh, Raheleh; Rabbani, Hossein; Abramoff, Michael D.; Sonka, Milan

    2015-01-01

    This study was conducted to determine the thickness map of eleven retinal layers in normal subjects by spectral domain optical coherence tomography (SD-OCT) and evaluate their association with sex and age. Mean regional retinal thickness of 11 retinal layers was obtained by automatic three-dimensional diffusion map based method in 112 normal eyes of 76 Iranian subjects. We applied our previously reported 3D intraretinal fast layer segmentation which does not require edge-based image information but rather relies on regional image texture. The thickness maps are compared among 9 macular sectors within 3 concentric circles as defined by ETDRS. The thickness map of central foveal area in layers 1, 3, and 4 displayed the minimum thickness. Maximum thickness was observed in nasal to the fovea of layer 1 and in a circular pattern in the parafoveal retinal area of layers 2, 3, and 4 and in central foveal area of layer 6. Temporal and inferior quadrants of the total retinal thickness and most of other quadrants of layer 1 were significantly greater in the men than in the women. Surrounding eight sectors of total retinal thickness and a limited number of sectors in layers 1 and 4 significantly correlated with age. PMID:25960888

  10. Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates

    SciTech Connect

    Narayanan, Vyshnavi; Lommens, Petra; De Buysser, Klaartje; Huehne, Ruben; Van Driessche, Isabel

    2011-11-15

    In this work, water-based precursor solutions suitable for dip-coating of thick La{sub 2}Zr{sub 2}O{sub 7} (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55{sup o}. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H{sub 2} gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer. - Graphical abstract: Thick LZO buffer layers from water-based precursor solutions were synthesized and their crystallinity, microstructure and buffer layer action were studied. The buffer layer action of the LZO layer was substantial to restrict the Ni penetration within 30 nm of a 140 nm thick film. Highlights: > LZO buffer layers with high thicknesses for use in coated conductors were prepared. > Prepared from water-based solutions. > Polymeric PVP increases the crack-free critical thickness of thick films. > Thick films showed good barrier action against Ni penetration. > Seed layers promote epitaxial growth of thick layers.

  11. Cloud layer thicknesses from a combination of surface and upper-air observations

    NASA Technical Reports Server (NTRS)

    Poore, Kirk D.; Wang, Junhong; Rossow, William B.

    1995-01-01

    Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 deg to 80 deg N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude.

  12. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    DOEpatents

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2001-01-01

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  13. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    SciTech Connect

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2004-01-27

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  14. Metaporous layer to overcome the thickness constraint for broadband sound absorption

    SciTech Connect

    Yang, Jieun; Lee, Joong Seok; Kim, Yoon Young

    2015-05-07

    The sound absorption of a porous layer is affected by its thickness, especially in a low-frequency range. If a hard-backed porous layer contains periodical arrangements of rigid partitions that are coordinated parallel and perpendicular to the direction of incoming sound waves, the lower bound of the effective sound absorption can be lowered much more and the overall absorption performance enhanced. The consequence of rigid partitioning in a porous layer is to make the first thickness resonance mode in the layer appear at much lower frequencies compared to that in the original homogeneous porous layer with the same thickness. Moreover, appropriate partitioning yields multiple thickness resonances with higher absorption peaks through impedance matching. The physics of the partitioned porous layer, or the metaporous layer, is theoretically investigated in this study.

  15. Effects of Membrane- and Catalyst-layer-thickness Nonuniformitiesin Polymer-electrolyte Fuel Cells

    SciTech Connect

    Weber, Adam Z.; Newman, John

    2006-09-01

    In this paper, results from mathematical, pseudo 2-D simulations are shown for four different along-the-channel thickness distributions of both the membrane and cathode catalyst layer. The results and subsequent analysis clearly demonstrate that for the membrane thickness distributions, cell performance is affected a few percent under low relative-humidity conditions and that the position along the gas channel is more important than the local thickness variations. However, for the catalyst-layer thickness distributions, global performance is not impacted, although for saturated conditions there is a large variability in the local temperature and performance depending on the thickness.

  16. Characterization and optimization of residual layer thickness during UV imprint process for singlemode waveguide fabrication

    NASA Astrophysics Data System (ADS)

    An, Shinmo; Lee, Hyun-Shik; Park, Se-Guen; O, Beom-Hoan; Lee, Seung-Gol; Lee, El-Hang

    2009-02-01

    We report on the fabrication and characterization of a residual layer resulting from UV imprinting of singlemode optical waveguide. We have measured the residual thickness formed from the imprinting process for several-um-size singlemode waveguide fabrication using the parameters of the imprinting pressure, dropped volume, and viscosity of the used polymer. We found that the residual layer thickness is dependent on both the initial polymer volume and process pressure and the initial polymer volume is more critical than process pressure. Viscosity of polymer also affects the residual layer thickness, the lowest residual layer thickness of 29nm is achieved with nano-imprinting resin, 0.3uL volume, and imprint pressure more than 20bar. Even with optical resin, the residual layer thickness of 60nm is achieved with 0.3uL volume and imprinting pressure of 30bar.

  17. Extending microcontact printing for patterning of thick polymer layers: semi-drying of inks and contact mechanisms

    NASA Astrophysics Data System (ADS)

    Kusaka, Yasuyuki; Miyashita, Kaori; Ushijima, Hirobumi

    2014-12-01

    We investigate the applicability of the microcontact printing technique for the patterning of polymeric etch-resistant layers with thicknesses in the order of micrometers. In contrast to small molecular materials such as thiols and silane coupling agents typically used in microcontact printing, the patterning of thick layers requires tuning of the rheological properties of an ink film to prevent pattern deformation and attain high-quality transfer. By evaluating the swelling rate of a microcontact stamp material (i.e. poly(dimethylsiloxane) (PDMS)) and the evaporation rate of solvents, we find an optimal ink formulation to attain the desired semi-dried state for the printing of polymer layers. In polymer films with solid content below the optimal limit, split- or wrinkle-type deformations were found depending on the adhesion force and deformability of ink films, while overly-dried polymer films failed to be transferred. These phenomena are in qualitative agreement with deformation curves obtained from colloidal probe microscopy measurements that successfully revealed the deformability and adhesion of semi-dried polymer films. Further investigation of the effects of stamp stiffness on pattern formation reveals that a pattern region in which the thickness profile has a small curvature radius failed to be transferred when a stiffer PDMS stamp was used. This type of defect is thought to be caused by incomplete contact between the film and substrate due to a semi-circular cap structure of the polymer film and insufficient deformation of the stamp. Herein, a detailed contacting mechanism for high-quality patterning is discussed on the basis of the Hertz contact model. Using the developed etch-resistant ink and optimized printing process conditions, a finely defined etched structure for a silicon substrate is obtained.

  18. The effect of chain rigidity on the interfacial layer thickness and dynamics of polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Cheng, Shiwang; Carrillo, Jan-Michael Y.; Carroll, Bobby; Sumpter, Bobby G.; Sokolov, Alexei P.

    There are growing experimental evidences showing the existence of an interfacial layer that has a finite thickness with slowing down dynamics in polymer nanocomposites (PNCs). Moreover, it is believed that the interfacial layer plays a significant role on various macroscopic properties of PNCs. A thicker interfacial layer is found to have more pronounced effect on the macroscopic properties such as the mechanical enhancement. However, it is not clear what molecular parameter controls the interfacial layer thickness. Inspired by our recent computer simulations that showed the chain rigidity correlated well with the interfacial layer thickness, we performed systematic experimental studies on different polymer nanocomposites by varying the chain stiffness. Combining small-angle X-ray scattering, broadband dielectric spectroscopy and temperature modulated differential scanning calorimetry, we find a good correlation between the polymer Kuhn length and the thickness of the interfacial layer, confirming the earlier computer simulations results. Our findings provide a direct guidance for the design of new PNCs with desired properties.

  19. Change in Tear Film Lipid Layer Thickness, Corneal Thickness, Volume and Topography after Superficial Cauterization for Conjunctivochalasis

    PubMed Central

    Chan, Tommy C. Y.; Ye, Cong; Ng, Paul KF; Li, Emmy Y. M.; Yuen, Hunter K. L.; Jhanji, Vishal

    2015-01-01

    We evaluated the change in tear film lipid layer thickness, corneal thickness, volume and topography after superficial cauterization of symptomatic conjunctivochalasis. Bilateral superficial conjunctival cauterization was performed in 36 eyes of 18 patients with symptomatic conjunctivochalasis. The mean age of patients (12 males, 6 females) was 68.6 ± 10.9 years (range: 44–83 years). Preoperatively, 28 eyes (77.8%) had grade 1 conjunctivochalasis, and 8 eyes (22.2%) had grade 2 conjunctivochalasis. At 1 month postoperatively, the severity of conjunctivochalasis decreased significantly (p < 0.001) and 29 eyes (80.6%) had grade 0 conjunctivochalasis whereas 7 eyes (19.4%) had grade 1 conjunctivochalasis. The mean Ocular Surface Disease Index score decreased from 31.5 ± 15.2 preoperatively to 21.5 ± 14.2 at the end of 1 month postoperatively (p = 0.001). There was a statistically significant increase in mean tear film lipid layer thickness 1 month after the surgery (49.6 ± 16.1 nm vs 62.6 ± 21.6 nm; p < 0.001). The central corneal thickness, thinnest corneal thickness and corneal volume decreased significantly postoperatively (p < 0.001). Our study showed that superficial conjunctival cauterization is an effective technique for management of conjunctivochalasis in the short term. An increase in tear film lipid layer thickness along with a decrease in corneal thickness and volume were observed after surgical correction of conjunctivochalasis. PMID:26184418

  20. Immobilized liquid layers: A new approach to anti-adhesion surfaces for medical applications.

    PubMed

    Sotiri, Irini; Overton, Jonathan C; Waterhouse, Anna; Howell, Caitlin

    2016-05-01

    Surface fouling and undesired adhesion are nearly ubiquitous problems in the medical field, complicating everything from surgeries to routine daily care of patients. Recently, the concept of immobilized liquid (IL) interfaces has been gaining attention as a highly versatile new approach to antifouling, with a wide variety of promising applications in medicine. Here, we review the general concepts behind IL layers and discuss the fabrication strategies on medically relevant materials developed so far. We also summarize the most important findings to date on applications of potential interest to the medical community, including the use of these surfaces as anti-thrombogenic and anti-bacterial materials, anti-adhesive textiles, high-performance coatings for optics, and as unique platforms for diagnostics. Although the full potential and pitfalls of IL layers in medicine are just beginning to be explored, we believe that this approach to anti-adhesive surfaces will prove broadly useful for medical applications in the future. PMID:27022136

  1. Characteristics of laser ultrasound interaction with multi-layered dissimilar metals adhesive interface by numerical simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Kuanshuang; Zhou, Zhenggan; Zhou, Jianghua; Sun, Guangkai

    2015-10-01

    The characteristics of laser-generated ultrasonic wave interaction with multi-layered dissimilar metals adhesive interface are investigated by finite element method (FEM). The physical model of laser-generated ultrasonic wave in the multi-layered dissimilar metals adhesive structure is built. The surface temperature evolution with different laser power densities is analyzed to obtain the parameters of pulsed laser with thermoelastic regime. The differences of laser ultrasonic waves with different center frequencies measured at the center of laser irradiation would verify the interfacial features of adhesive structures. The optimum frequency range and probe point would be beneficial for the detection of the small void defect. The numerical results indicate that the different frequency range and probe points would evidently influence the identification and quantitative characterization of the small void defect. The research findings would lay a foundation for testing interfacial integrity.

  2. Enhancing the adhesion strength of micro electroforming layer by ultrasonic agitation method and the application.

    PubMed

    Zhao, Zhong; Du, Liqun; Tao, Yousheng; Li, Qingfeng; Luo, Lei

    2016-11-01

    Micro electroforming is widely used for fabricating micro metal devices in Micro Electro Mechanism System (MEMS). However, there is the problem of poor adhesion strength between micro electroforming layer and substrate. This dramatically influences the dimensional accuracy of the device. To solve this problem, ultrasonic agitation method is applied during the micro electroforming process. To explore the effect of the ultrasonic agitation on the adhesion strength, micro electroforming experiments were carried out under different ultrasonic power (0W, 100W, 150W, 200W, 250W) and different ultrasonic frequencies (0kHz, 40kHz, 80kHz, 120kHz, 200kHz). The effects of the ultrasonic power and the ultrasonic frequency on the micro electroforming process were investigated by polarization method and alternating current (a.c.) impedance method. The adhesion strength between the electroforming layer and the substrate was measured by scratch test. The compressive stress of the electroforming layer was measured by X-ray Diffraction (XRD) method. The crystallite size of the electroforming layer was measured by Transmission Electron Microscopy (TEM) method. The internal contact surface area of the electroforming layer was measured by cyclic voltammetry (CV) method. The experimental results indicate that the ultrasonic agitation can decrease the polarization overpotential and increase the charge transfer process. Generally, the internal contact surface area is increased and the compressive stress is reduced. And then the adhesion strength is enhanced. Due to the different depolarization effects of the ultrasonic power and the ultrasonic frequency, the effects on strengthening the adhesion strength are different. When the ultrasonic agitation is 200W and 40kHz, the effect on strengthening the adhesion strength is the best. In order to prove the effect which the ultrasonic agitation can improve the adhesion strength of the micro devices, micro pillar arrays were fabricated under

  3. Study of the thickness of liquid layers by moiré deflectometry.

    PubMed

    Yogev, D; Efrima, S; Kafri, O

    1988-10-01

    We suggest and demonstrate a novel method for studying the thickness of thin liquid layers. The method is based on ray-deflection analysis of a beam reflected from the edge of the layer and on studying the topography of the layer. PMID:19746084

  4. The Effect of Axial Length on the Thickness of Intraretinal Layers of the Macula

    PubMed Central

    Szigeti, Andrea; Tátrai, Erika; Varga, Boglárka Enikő; Szamosi, Anna; DeBuc, Delia Cabrera; Nagy, Zoltán Zsolt; Németh, János; Somfai, Gábor Márk

    2015-01-01

    Purpose The aim of this study was to evaluate the effect of axial length (AL) on the thickness of intraretinal layers in the macula using optical coherence tomography (OCT) image analysis. Methods Fifty three randomly selected eyes of 53 healthy subjects were recruited for this study. The median age of the participants was 29 years (range: 6 to 67 years). AL was measured for each eye using a Lenstar LS 900 device. OCT imaging of the macula was also performed by Stratus OCT. OCTRIMA software was used to process the raw OCT scans and to determine the weighted mean thickness of 6 intraretinal layers and the total retina. Partial correlation test was performed to assess the correlation between the AL and the thickness values. Results Total retinal thickness showed moderate negative correlation with AL (r = -0.378, p = 0.0007), while no correlation was observed between the thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCC), retinal pigment epithelium (RPE) and AL. Moderate negative correlation was observed also between the thickness of the ganglion cell layer and inner plexiform layer complex (GCL+IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and AL which were more pronounced in the peripheral ring (r = -0.402, p = 0.004; r = -0.429, p = 0.002; r = -0.360, p = 0.01; r = -0.448, p = 0.001). Conclusions Our results have shown that the thickness of the nuclear layers and the total retina is correlated with AL. The reason underlying this could be the lateral stretching capability of these layers; however, further research is warranted to prove this theory. Our results suggest that the effect of AL on retinal layers should be taken into account in future studies. PMID:26544553

  5. An ultrasonic theoretical and experimental approach to determine thickness and wave speed in layered media.

    PubMed

    de Sousa, Ana Valéria Greco; Pereira, Wagner Coelho de Albuquerque; Machado, João Carlos

    2007-02-01

    This work presents an ultrasonic method to characterize the layers of a stratified medium, using independent measurements of wave speed and thickness of each layer. The model, based on geometrical acoustics, includes refraction. Two transducers are used: one active (3.4 MHz) and a hydrophone as a receptor, which is moved laterally through 15 positions. The distance between the transducers and the delay between the echoes, from the interfaces separating the layers, received by them are used to estimate the speed and thickness. Three types of layered phantoms were used: Ph1 made with alcohol/acrylic, Ph2 made with polyvinyl chloride/water/acrylic, and Ph3 made with acrylic/water/polyvinyl chloride. The experimental results for speed of sound and layer thickness presented an experimental mean relative error, for thickness and wave speed, lower than 7.0% and 6.6%, respectively. PMID:17328335

  6. Effect of layer thickness on the properties of nickel thermal sprayed steel

    NASA Astrophysics Data System (ADS)

    Nurisna, Zuhri; Triyono, Muhayat, Nurul; Wijayanta, Agung Tri

    2016-03-01

    Thermal arc spray nickel coating is widely used for decorative and functional applications, by improving corrosion resistance, wear resistance, heat resistence or by modifying other properties of the coated materials. There are several properties have been studied. Layer thickness of nickel thermal sprayed steel may be make harder the substrate surface. In this study, the effect of layer thickness of nickel thermal sprayed steel has been investigated. The rectangular substrate specimens were coated by Ni-5 wt.% Al using wire arc spray method. The thickness of coating layers were in range from 0.4 to 1.0 mm. Different thickness of coating layers were conducted to investigate their effect on hardness and morphology. The coating layer was examined by using microvickers and scanning electron microscope with EDX attachment. Generally, the hardness at the interface increased with increasing thickness of coating layers for all specimens due to higher heat input during spraying process. Morphology analysis result that during spraying process aluminum would react with surrounding oxygen and form aluminum oxide at outer surface of splat. Moreover, porosity was formed in coating layers. However, presence porosity is not related to thickness of coating material. The thicker coating layer resulted highesr of hardness and bond strength.

  7. Inversion of lunar regolith layer thickness with CELMS data using BPNN method

    NASA Astrophysics Data System (ADS)

    Meng, Zhiguo; Xu, Yi; Zheng, Yongchun; Zhu, Yongchao; Jia, Yu; Chen, Shengbo

    2014-10-01

    Inversion of the lunar regolith layer thickness is one of the scientific objectives of current Moon research. In this paper, the global lunar regolith layer thickness is inversed with the back propagation neural network (BPNN) technique. First, the radiative transfer simulation is employed to study the relationship between the lunar regolith layer thickness d and the observed brightness temperature TB's. The simulation results show that the parameters such as the surface roughness σ, slope θs and the (FeO+TiO2) abundance S have strong influence on the observed TB's. Therefore, TB's, σ, θs and S are selected as the inputs of the BPNN network. Next, the four-layer BPNN network with seven-dimension input and two hidden layers is constructed by taking nonlinearity into account with sigmoid functions. Then, BPNN network is trained with the corresponding parameters collected in Apollo landing sites. To tackle issues introduced by the small number of the training samples, the six-dimension similarity degree is introduced to indicate similarities of the inversion results to the correspondent training samples. Thus, the output lunar regolith layer thickness is defined as the sum of the product of the similarity degree and the thickness at the corresponding landing site. Once training phase finishes, the lunar regolith layer thickness can be inversed speedily with the four-channel TB's concluded from the CELMS data, σ and θs estimated from LOLA data and S derived from Clementine UV/vis data. the inversed thickness agrees well with the values estimated by ground-based radar data in low latitude regions. The results indicate that the thickness in the maria varies from about 0.5 m to 12 m, and the mean is about 6.52 m; while the thickness in highlands is a bit thicker than the previous estimation, where the thickness varies widely from 10 m to 31.5 m, and the mean thickness is about 16.8 m. In addition, the relation between the ages, the (FeO+TiO2) abundance and the

  8. Hierarchy of adhesion forces in patterns of photoreactive surface layers

    NASA Astrophysics Data System (ADS)

    Hlawacek, Gregor; Shen, Quan; Teichert, Christian; Lex, Alexandra; Trimmel, Gregor; Kern, Wolfgang

    2009-01-01

    Precise control of surface properties including electrical characteristics, wettability, and friction is a prerequisite for manufacturing modern organic electronic devices. The successful combination of bottom up approaches for aligning and orienting the molecules and top down techniques to structure the substrate on the nano- and micrometer scale allows the cost efficient fabrication and integration of future organic light emitting diodes and organic thin film transistors. One possibility for the top down patterning of a surface is to utilize different surface free energies or wetting properties of a functional group. Here, we used friction force microscopy (FFM) to reveal chemical patterns inscribed by a photolithographic process into a photosensitive surface layer. FFM allowed the simultaneous visualization of at least three different chemical surface terminations. The underlying mechanism is related to changes in the chemical interaction between probe and film surface.

  9. Evidence for a non-linear relationship between fracture spacing and layer thickness

    NASA Astrophysics Data System (ADS)

    Mandal, Nibir; Deb, Sanjitendra Krishna; Khan, Debdarpan

    1994-09-01

    In experiments, extension fractures were generated in rigid layers of Plaster of Paris resting on a viscous substratum (pitch). The experimental results predict a non-linear relationship between the spacing of fractures in uniform brittle layers and layer thickness for fractures generated by the tractional force of embeddins weak rocks. We derive an equation which relates the critical fracture spacing ( λc) with layer thickness ( b), tensile strength of the layer material/viscosity of the embedding medium ratio ( τo/ η) and bulk strain rate ( ɛ˙b). The equation shows that the spacing increases as a function of the square root of the layer thickness. The theory also predicts that the fracture spacing depends on the strain rate when the embedding weak medium is viscous.

  10. 2D Graphene Oxide Nanosheets as an Adhesive Over-Coating Layer for Flexible Transparent Conductive Electrodes

    NASA Astrophysics Data System (ADS)

    Moon, In Kyu; Kim, Jae Il; Lee, Hanleem; Hur, Kangheon; Kim, Woon Chun; Lee, Hyoyoung

    2013-01-01

    In recent, highly transparent and flexible, two-dimensional (2D) graphene oxide (GO) nanosheet has been paid attention for various applications. Due to an existence of a large amount of oxygen functional groups, the single 2D GO nanosheet has an insulating, transparent, highly dispersible in the eco-friendly water, and hydrophilic property that has strong adhesion to the hydrophilic surface, which will be the best candidate for the use of an over-coating layer (OCL) and protecting layer for a conductive nanowire based indium-free transparent conductive film (TCF). The ultrathin 2D adhesive GO OCL nanosheet is expected to tightly hold silver nanowires (AgNWs), reduce sheet resistance and produce uniform TCF, providing complete solution that simultaneously solves a high haze, low transparency with a conventional OCL and mechanical instability in cases without a thick OCL. Our novel 2D insulating and hydrophilic GO OCL successfully provided a large-area, flexible, and highly transparent AgNW TCF.

  11. Hydrophobic and high adhesive polyaniline layer of rectangular microtubes fabricated by a modified interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Zhou, Chuanqiang; Gong, Xiangxiang; Qu, Yun; Han, Jie

    2016-08-01

    A modified interfacial polymerization of aniline is developed to fabricate hydrophobic and adhesive polyaniline (PANI) layer of rectangular microtubes on the glass substrate. The modified method uses pentanol as an organic medium to dissolve aniline monomer, with the water film of oxidant and surfactant on the glass substrate as water phase. The effects of some synthetic parameters (such as monomer concentration, alcohol molecular structure and surfactant type) on the morphology of PANI layer are studied for better understanding the fabrication of PANI nanostructures on the film. The alcohol molecular structure plays key role for the supermolecular assembly of PANI chains into nanostructures, while the surfactant may direct the array and deposition of these nanostructures on the glass substrate. The formation reason of PANI rectangular sub-microtubes is roughly interpreted according to our previous works. Wettability experiment indicates that the as-prepared PANI layer exhibits excellent hydrophobicity and high adhesive properties to water drop.

  12. Detection of charged particles in thick hydrogenated amorphous silicon layers

    SciTech Connect

    Fujieda, I.; Cho, G.; Kaplan, S.N.; Perez-Mendez, V.; Qureshi, S.; Ward, W.; Street, R.A.

    1988-03-01

    We show our results in detecting particles of various linear energy transfer, including minimum ionizing electrons from a Sr-90 source with 5 to 12 micron thick n-i-p and p-i-n diodes. We measured W ( average energy to produce one electron-hole pair) using 17keV filtered xray pulses with a result W = 6.0 /+-/ 0.2eV. This is consistent with the expected value for a semiconductor with band gap of 1.7 to 1.9eV. With heavily ionizing particles such as 6 MeV alphas and 1 to 2 MeV protons, there was some loss of signal due to recombination in the particle track. The minimum ionizing electrons showed no sign of recombination. Applications to pixel and strip detectors for physics experiments and medical imaging will be discussed. 7 refs., 8 figs.

  13. Monte Carlo modeling (MCML) of light propagation in skin layers for detection of fat thickness

    NASA Astrophysics Data System (ADS)

    Nilubol, Chonnipa; Treerattrakoon, Kiatnida; Mohammed, Waleed S.

    2010-05-01

    Nowadays, most activities require lesser physical actions, which could ultimately lead to accumulation of excessive body fat. The main roles of body fat are to store energy and acts as various kinds of insulators for the body. The thickness of fat layers can be measured to indicate fat-body weight ratio. Exceeding the body-mass index (BMI) could lead to many illnesses regarding obesity. Consequently, many studies have proposed various principles and techniques to measure the amount of fat within one's body. In this paper, infrared interactance in skin layers is studied for investigation of the influence of fat thickness upon photon travelling pattern in skin tissues using Monte Carlo model (MCML). Photon propagation is numerically simulated in simplified multi-layered tissues. The optical coefficients of each skin layers are accounted for different traveling paths of photons that move through random motion. The thickness of fat layer is varied, and changing in optical parameters is observed. Then the statistically obtained data are computed and analyzed for the effect of the fat layer upon reflection percentage using different wavelengths. The calculations have shown increment in the slope of change of reflection percentage versus fat thickness, when using infrared compare to visible light. This technique can be used to construct a mobile device that is capable of measuring the volume fraction of melanin and blood in the epidermis layer and dermis layer, to calculate for the necessary optical coefficients that would be necessary for measurement of fat thickness.

  14. Layer thickness-dependent phonon properties and thermal conductivity of MoS2

    NASA Astrophysics Data System (ADS)

    Gu, Xiaokun; Li, Baowen; Yang, Ronggui

    2016-02-01

    For conventional materials, the thermal conductivity of thin films is usually suppressed when the thickness decreases due to phonon-boundary scattering. However, this is not necessarily true for the van der Waals solids if the thickness is reduced to only a few layers. In this letter, the layer thickness-dependent phonon properties and thermal conductivity in the few-layer MoS2 are studied using the first-principles-based Peierls-Boltzmann transport equation approach. The basal-plane thermal conductivity of 10-μm-long samples is found to monotonically reduce from 138 W/mK to 98 W/mK for naturally occurring MoS2, and from 155 W/mK to 115 W/mK for isotopically pure MoS2, when its thickness increases from one layer to three layers. The thermal conductivity of tri-layer MoS2 approaches to that of bulk MoS2. Both the change of phonon dispersion and the thickness-induced anharmonicity are important for explaining such a thermal conductivity reduction. The increased anharmonicity in bi-layer MoS2 results in stronger phonon scattering for ZAi modes, which is linked to the breakdown of the symmetry in single-layer MoS2.

  15. Microstructure evolution with varied layer thickness in magnetron-sputtered Ni/C multilayer films

    PubMed Central

    Peng, Jichang; Li, Wenbin; Huang, Qiushi; Wang, Zhanshan

    2016-01-01

    The microstructure evolution of magnetron-sputtered Ni/C multilayers was investigated by varying the Ni and C layer thickness in the region of a few nanometers. For the samples having 2.6-nm-thick C layers, the interface width increases from 0.37 to 0.81 nm as the Ni layer thickness decreases from 4.3 to 1.3 nm. Especially for the samples with Ni layers less than 2.0 nm, the interface width changes significantly due to the discontinuously distributed Ni crystallites. For the samples having 2.8-nm-thick Ni layers, the interface width increases from 0.37 to 0.59 nm when the C layer thickness decreases from 4.3 to 0.7 nm. The evolution of interface microstructures with varied Ni and C layers is explained based on a proposed simple growth model of Ni and C layers. PMID:27515586

  16. Titanium Oxide Adhesion Layer for High Temperature Annealed Si/Si3N4/TiO x /Pt/LiCoO2 Battery Structures

    NASA Astrophysics Data System (ADS)

    Vieira, E. M. F.; Ribeiro, J. F.; Sousa, R.; Silva, M. M.; Dupont, L.; Gonçalves, L. M.

    2016-02-01

    This work describes the influence of a high annealing temperature of about 700°C on the Si(substrate)/Si3N4/TiO x /Pt/LiCoO2 multilayer system for the fabrication of all-solid-state lithium ion thin film microbatteries. Such micro-batteries typically utilize lithium cobalt oxide (LiCoO2) as cathode material with a platinum (Pt) current collector. Silicon nitride (Si3N4) is used to act as a barrier against Li diffusion into the substrate. For a good adherence between Si3N4 and Pt, commonly titanium (Ti) is used as intermediate layer. However, to achieve crystalline LiCoO2 the multilayer system has to be annealed at high temperature. This post-treatment initiates Ti diffusion into the Pt-collector and an oxidation to TiO x , leading to volume expansion and adhesion failures. To solve this adhesion problem, we introduce titanium oxide (TiO x ) as an adhesion layer, avoiding the diffusion during the annealing process. LiCoO2, Pt and Si3N4 layers were deposited by magnetron sputtering and the TiO x layer by thermal oxidation of Ti layers deposited by e-beam technique. As-deposited and annealed multilayer systems using various TiO x layer thicknesses were studied by scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS). The results revealed that an annealing process at temperature of 700°C leads to different interactions of Ti atoms between the layers, for various TiO x layer thicknesses (25-45 nm).

  17. Observation of three crystalline layers in hydrothermally grown BiFeO{sub 3} thick films

    SciTech Connect

    Lee, T. K.; Sung, K. D.; Jung, J. H.; Kim, T. H.; Ko, J.-H.

    2014-11-21

    We report the observation of three different crystalline layers in hydrothermally grown BiFeO{sub 3} (BFO) thick films on SrRuO{sub 3}/SrTiO{sub 3} substrates. High-resolution X-ray diffraction and transmission electron microcopy results suggest that compressively strained, partially relaxed epitaxial layers, and a mixture of polycrystalline and amorphous BFO layers, were successively formed from the bottom to the top of the films. The resistance and capacitance of the mixed layer were significantly lower than those of the epitaxial layers. The atomic concentrations of Bi and Fe in the mixed layer were fluctuating for each point. Based on the observed three crystalline layers, we have discussed the growth mechanism and the leakage current of hydrothermally grown BFO thick films.

  18. The enhanced characteristics of osteoblast adhesion to photofunctionalized nanoscale TiO2 layers on biomaterials surfaces.

    PubMed

    Miyauchi, Tomohiko; Yamada, Masahiro; Yamamoto, Akiko; Iwasa, Fuminori; Suzawa, Tetsuo; Kamijo, Ryutaro; Baba, Kazuyoshi; Ogawa, Takahiro

    2010-05-01

    Recently, UV photofunctionalization of titanium has been shown to be effective in enhancing osteogenic environment around this functional surface, in particular for the use of endosseous implants. However, the underlying mechanism remains unknown and its potential application to other tissue engineering materials has never been explored. We determined whether adhesion of a single osteoblast is enhanced on UV-treated nano-thin TiO(2) layer with virtually no surface roughness or topographical features. Rat bone marrow-derived osteoblasts were cultured on UV-treated or untreated 200-nm thick TiO(2) sputter-coated glass plates. After an incubation of 3 h, the mean critical shear force required to initiate detachment of a single osteoblast was determined to be 1280 +/- 430 nN on UV-treated TiO(2) surfaces, which was 2.5-fold greater than the force required on untreated TiO(2) surfaces. The total energy required to complete the detachment was 37.0 +/- 23.2 pJ on UV-treated surfaces, 3.5-fold greater than that required on untreated surfaces. Such substantial increases in single cell adhesion were also observed for osteoblasts cultured for 24 h. Osteoblasts on UV-treated TiO(2) surfaces were larger and characterized with increased levels of vinculin expression and focal contact formation. However, the density of vinculin or focal contact was not influenced by UV treatment. In contrast, both total expression and density of actin fibers increased on UV-treated surfaces. Thin layer TiO(2) coating and UV treatment of Co-Cr alloy and PTFE membrane synergistically resulted in a significant increase in the ability of cell attachment and osteoblastic production of alkaline phosphatase. These results indicated that the adhesive nature of a single osteoblast is substantially enhanced on UV-treated TiO(2) surfaces, providing the first evidence showing that each individual cell attached to these surfaces is substantially more resistant to exogenous load potentially from blood and

  19. Effect of Thickness on Surface Morphology of Silver Nanoparticle Layer During Furnace Sintering

    NASA Astrophysics Data System (ADS)

    Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Moon, Seung-Jae; Young hwang, Jun

    2015-04-01

    In printed electronics applications, specific resistances of conductive lines are critical to the performance of the devices. The specific resistance of a silver (Ag) nanoparticle electrode is affected by surface morphology of the layered nanoparticles which were sintered by the heat treatment after printing. In this work, the relationship between surface morphology and specific resistance was investigated with various sintering temperatures and various layer thicknesses of Ag nanoparticle ink. Ag nanoparticles with an average size of approximately 50 nm were spin-coated on Eagle XG glass substrates with various spin speed to change the layer thickness of Ag nanoparticles from 200 nm to 900 nm. Coated Ag nanoparticle layers were heated from 150°C to 450°C for 30 min in a furnace. The result showed that higher sintering temperature produces larger grains in an Ag layer and decreases specific resistance of the layer, but that the maximum allowable heating temperature is limited by the thickness of the layer. When grain size exceeded the thickness of the layer, the morphology of the Ag nanoparticles changed to submicron-sized islands and the Ag layers did not have electrical conductivity any more.

  20. Substrate effect modulates adhesion and proliferation of fibroblast on graphene layer.

    PubMed

    Lin, Feng; Du, Feng; Huang, Jianyong; Chau, Alicia; Zhou, Yongsheng; Duan, Huiling; Wang, Jianxiang; Xiong, Chunyang

    2016-10-01

    Graphene is an emerging candidate for biomedical applications, including biosensor, drug delivery and scaffold biomaterials. Cellular functions and behaviors on different graphene-coated substrates, however, still remain elusive to a great extent. This paper explored the functional responses of cells such as adhesion and proliferation, to different kinds of substrates including coverslips, silicone, polydimethylsiloxane (PDMS) with different curing ratios, PDMS treated with oxygen plasma, and their counterparts coated with single layer graphene (SLG). Specifically, adherent cell number, spreading area and cytoskeleton configuration were exploited to characterize cell-substrate adhesion ability, while MTT assay was employed to test the proliferation capability of fibroblasts. Experimental outcome demonstrated graphene coating had excellent cytocompatibility, which could lead to an increase in early adhesion, spreading, proliferation, and remodeling of cytoskeletons of fibroblast cells. Notably, it was found that the underlying substrate effect, e.g., stiffness of substrate materials, could essentially regulate the adhesion and proliferation of cells cultured on graphene. The stiffer the substrates were, the stronger the abilities of adhesion and proliferation of fibroblasts were. This study not only deepens our understanding of substrate-modulated interfacial interactions between live cells and graphene, but also provides a valuable guidance for the design and application of graphene-based biomaterials in biomedical engineering. PMID:27451366

  1. Shear Dependent Adhesion of Leukocytes and Lectins to the Endothelium and Concurrent Changes in Thickness of the Glycocalyx of Post-capillary Venules in the Low Flow State

    PubMed Central

    Lipowsky, Herbert H.; Lescanic, Anne

    2012-01-01

    Objectives To elucidate shear dependent effects of deformation of the endothelial glycocalyx on adhesion of circulating ligands in post-capillary venules, and delineate effect of matrix metalloproteases (MMPs). Methods Adhesion of leukocytes (WBCs) and lectin-coated fluorescently labeled microspheres (FLMs, 0.1 μm diameter), to endothelium (EC) of post-capillary venules in mesentery was examined during acute reductions in shear rates (γ̇, hemorrhagic hypotension). Adhesion was examined with or without superfusion with 0.5 μM doxycycline to inhibit MMPs. Thickness of the glycocalyx was measured by exclusion of fluorescent 70 kDa dextran from the EC surface. Results During superfusion with Ringers, rapid reductions in γ̇ resulted in a significant rise in WBC adhesion and a two-fold rise in microsphere adhesion. With addition of doxycycline WBC and FLM adhesion increased two-fold under high and low flow conditions. FLM adhesion was invariant with γ̇ throughout the network in the normal (high) flow state. With reductions in γ̇, thickness of the glycocalyx increased significantly, with or without doxycycline. Conclusions The concurrent increase in WBC and FLM adhesion with increased thickness of the glycocalyx during reductions in shear suggests that glycocalyx core proteins recoil from their deformed steady state configuration, which increases exposure of binding sites for circulating ligands. PMID:22963321

  2. Computational and numerical aspects of using the integral equation method for adhesive layer fracture mechanics analysis

    SciTech Connect

    Giurgiutiu, V.; Ionita, A.; Dillard, D.A.; Graffeo, J.K.

    1996-12-31

    Fracture mechanics analysis of adhesively bonded joints has attracted considerable attention in recent years. A possible approach to the analysis of adhesive layer cracks is to study a brittle adhesive between 2 elastic half-planes representing the substrates. A 2-material 3-region elasticity problem is set up and has to be solved. A modeling technique based on the work of Fleck, Hutchinson, and Suo is used. Two complex potential problems using Muskelishvili`s formulation are set up for the 3-region, 2-material model: (a) a distribution of edge dislocations is employed to simulate the crack and its near field; and (b) a crack-free problem is used to simulate the effect of the external loading applied in the far field. Superposition of the two problems is followed by matching tractions and displacements at the bimaterial boundaries. The Cauchy principal value integral is used to treat the singularities. Imposing the traction-free boundary conditions over the entire crack length yielded a linear system of two integral equations. The parameters of the problem are Dundurs` elastic mismatch coefficients, {alpha} and {beta}, and the ratio c/H representing the geometric position of the crack in the adhesive layer.

  3. Effect of layer thickness on device response of silicon heavily supersaturated with sulfur

    NASA Astrophysics Data System (ADS)

    Hutchinson, David; Mathews, Jay; Sullivan, Joseph T.; Akey, Austin; Aziz, Michael J.; Buonassisi, Tonio; Persans, Peter; Warrender, Jeffrey M.

    2016-05-01

    We report on a simple experiment in which the thickness of a hyperdoped silicon layer, supersaturated with sulfur by ion implantation followed by pulsed laser melting and rapid solidification, is systematically varied at constant average sulfur concentration, by varying the implantation energy, dose, and laser fluence. Contacts are deposited and the external quantum efficiency (EQE) is measured for visible wavelengths. We posit that the sulfur layer primarily absorbs light but contributes negligible photocurrent, and we seek to support this by analyzing the EQE data for the different layer thicknesses in two interlocking ways. In the first, we use the measured concentration depth profiles to obtain the approximate layer thicknesses, and, for each wavelength, fit the EQE vs. layer thickness curve to obtain the absorption coefficient of hyperdoped silicon for that wavelength. Comparison to literature values for the hyperdoped silicon absorption coefficients [S.H. Pan et al. Applied Physics Letters 98, 121913 (2011)] shows good agreement. Next, we essentially run this process in reverse; we fit with Beer's law the curves of EQE vs. hyperdoped silicon absorption coefficient for those wavelengths that are primarily absorbed in the hyperdoped silicon layer, and find that the layer thicknesses obtained from the fit are in good agreement with the original values obtained from the depth profiles. We conclude that the data support our interpretation of the hyperdoped silicon layer as providing negligible photocurrent at high S concentrations. This work validates the absorption data of Pan et al. [Applied Physics Letters 98, 121913 (2011)], and is consistent with reports of short mobility-lifetime products in hyperdoped layers. It suggests that for optoelectronic devices containing hyperdoped layers, the most important contribution to the above band gap photoresponse may be due to photons absorbed below the hyperdoped layer.

  4. Optical Coherence Tomography Assisted Retinal Nerve Fibre Layer Thickness Profile in High Myopia

    PubMed Central

    Malakar, Mousumi; Askari, Syed Nasir; Ashraf, Humayun; Ahuja, Anupam; Asghar, Adil

    2015-01-01

    Introduction: To evaluate the association of high myopia with retinal nerve fibre layer (RNFL) thickness by Fourier domain optical coherence tomography (FD OCT). Materials and Methods: Fifty highly myopic eyes (25 patients) and forty emmetropic eyes (20 Normal subject) were randomly selected after excluding concomitant ophthalmic disorder and RNFL thickness measured using the Fourier domain optical coherence tomography (FD OCT). Results: The overall mean RNFL thickness in the myopic groups and control were 87.89 μm and 111.64 μm respectively. The mean retinal nerve fibre thickness was significantly less in myopic eyes as compared to control group (p =0.0001). Retinal nerve fibre layer thickness shows topographic double hump pattern in both the groups (myopes and emmetropes). Conclusion: Retinal nerve fibre thickness was significantly less in myopic eyes as compared to emmetropic eyes. The retinal nerve fibre layer thinning in high myopes may be confused with open angle glaucoma, a disease also prevalent in high myopes. There is therefore a need to have retinal nerve fibre layer thickness normogram for high myopes of a given population group to avoid wrong interpretation. PMID:25859476

  5. Influences and interactions of inundation, peat, and snow on active layer thickness

    DOE PAGESBeta

    Atchley, Adam L.; Coon, Ethan T.; Painter, Scott L.; Harp, Dylan R.; Wilson, Cathy J.

    2016-05-18

    The effect of three environmental conditions: 1) thickness of organic soil, 2) snow depth, and 3) soil moisture content or water table height above and below the soil surface, on active layer thickness (ALT) are investigated using an ensemble of 1D thermal hydrology models. Sensitivity analyses of the ensemble exposed the isolated influence of each environmental condition on ALT and their multivariate interactions. The primary and interactive influences are illustrated in the form of color maps of ALT change. Results show that organic layer acts as a strong insulator, and its thickness is the dominant control of ALT, but themore » strength of the effect of organic layer thickness is dependent on the saturation state. Snow depth, subsurface saturation, and ponded water depth are strongly codependent and positively correlated to ALT.« less

  6. Influences of Peat, Surface and Subsurface Water, and Snow on Active Layer Thickness

    SciTech Connect

    Atchley, Adam; Coon, Ethan T.; Painter, Scott L; Harp, Dylan; Wilson, Cathy

    2016-01-01

    The effect of three environmental conditions: 1) thickness of organic soil, 2) snow depth, and 3) soil moisture content or water table height above and below the soil surface, on active layer thickness (ALT) are investigated using an ensemble of 1D thermal hydrology models. Sensitivity analyses of the ensemble exposed the isolated influence of each environmental condition on ALT and their multivariate interactions. The primary and interactive influences are illustrated in the form of color maps of ALT change. Results show that organic layer acts as a strong insulator, and its thickness is the dominant control of ALT, but the strength of the effect of organic layer thickness is dependent on the saturation state. Snow depth, subsurface saturation, and ponded water depth are strongly codependent and positively correlated to ALT.

  7. Influences of Peat, Surface and Subsurface Water, and Snow on Active Layer Thickness

    DOE PAGESBeta

    Atchley, Adam; Coon, Ethan T.; Painter, Scott L; Harp, Dylan; Wilson, Cathy

    2016-01-01

    The effect of three environmental conditions: 1) thickness of organic soil, 2) snow depth, and 3) soil moisture content or water table height above and below the soil surface, on active layer thickness (ALT) are investigated using an ensemble of 1D thermal hydrology models. Sensitivity analyses of the ensemble exposed the isolated influence of each environmental condition on ALT and their multivariate interactions. The primary and interactive influences are illustrated in the form of color maps of ALT change. Results show that organic layer acts as a strong insulator, and its thickness is the dominant control of ALT, but themore » strength of the effect of organic layer thickness is dependent on the saturation state. Snow depth, subsurface saturation, and ponded water depth are strongly codependent and positively correlated to ALT.« less

  8. Characteristics of blue organic light emitting diodes with different thick emitting layers

    NASA Astrophysics Data System (ADS)

    Li, Chong; Tsuboi, Taiju; Huang, Wei

    2014-08-01

    We fabricated blue organic light emitting diodes (called blue OLEDs) with emitting layer (EML) of diphenylanthracene derivative 9,10-di(2-naphthyl)anthracene (ADN) doped with blue-emitting DSA-ph (1-4-di-[4-(N,N-di-phenyl)amino]styryl-benzene) to investigate how the thickness of EML and hole injection layer (HIL) influences the electroluminescence characteristics. The driving voltage was observed to increase with increasing EML thickness from 15 nm to 70 nm. The maximum external quantum efficiency of 6.2% and the maximum current efficiency of 14 cd/A were obtained from the OLED with 35 nm thick EML and 75 nm thick HIL. High luminance of 120,000 cd/m2 was obtained at 7.5 V from OLED with 15 nm thick EML.

  9. [Research advances of retinal nerve fiber layer thickness and its association with myopia].

    PubMed

    Kang, M T; Ran, A R; Wang, N L; Li, S M

    2016-05-11

    Recently, the distribution characteristics of retinal nerve fiber layer thickness in myopic population have raised scholars' attention. The retinal nerve fiber layer thickness is varied with different refractive statuses, and is correlated to many factors like age, eye elongation, and fundus changes. Further exploration of the relationship between myopia and retinal structure and function will promote our understanding and knowledge of the pathogenesis of myopia. The article reviews the structure characteristics of the retinal nerve fiber layer, its associations with demographic characteristics, its characteristics in myopia, and the structural-functional relationship.(Chin J Ophthalmol, 2016, 52: 396-400). PMID:27220715

  10. Assessment of the Correlation between Crust and its Estimated Elastic Layer Thickness in Iran

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, Majid; Nikkhoo, Mehdi

    2010-05-01

    Although crust plates movements are usually just under few centimeters during a year, it can deform elastic layer of rocks on the faults and, as a result, energy stores in the layer. Sometimes, just in a few seconds, the accumulated energy within the layer releases suddenly and an earthquake occur. The effective elastic thickness of lithosphere has a prominent role to predict the focal depth of earthquakes and their magnitude, as well. Since lithosphere is flexed by the mass of topography on the earth's surface, the spectral analysis of topography and gravity anomaly is an appropriate method to assess the flexure of lithosphere and estimate its elastic layer thickness. In this paper, by spectral analysis of free-air gravity anomaly and topography signals which were generated respectively from EIGEN-GL04C and ETOPO5 global models; elastic layer thickness in different regions of Iran are calculated. Comparing the crust thickness (obtained from CRUST2.0 model) and the estimated elastic layer thickness, a statistically significant correlation between the two parameters could be seen.

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

    SciTech Connect

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

    2015-12-29

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

  12. Miniature fuel cell with monolithically fabricated Si electrodes - Uniformity of Catalyst Layer Thickness -

    NASA Astrophysics Data System (ADS)

    Morisawa, Itsuki; Suzuki, Takahiro; Katayama, Noboru; Dowaki, Kiyoshi; Hayase, Masanori

    2014-11-01

    Uniformity of catalyst layer thickness was improved to obtained higher output with our miniature fuel cells. Though the miniature fuel cells demonstrated high power density about 500mW/cm2 with 1 mm2 reaction area, it was difficult to maintain the power density with larger reaction area and careful observation of the prototypes revealed that the porous Si layer, which should be etched away completely, remained on the channel bottoms. Nonuniform porous Pt catalyst layer thickness was suspicious for the residual porous Si, and rotation of the plating vessel in the Pt deposition process was performed to mitigate variation of the catalyst layer thickness. Though the power density was still low with larger reaction area, the larger output was successfully obtained with the vessel rotation.

  13. Analysis of Retinal Layer Thicknesses and Their Clinical Correlation in Patients with Traumatic Optic Neuropathy

    PubMed Central

    Lee, Ju-Yeun; Cho, Kyuyeon; Park, Kyung-Ah; Oh, Sei Yeul

    2016-01-01

    The aims of this study were 1) To evaluate retinal nerve fiber layer (fRNFL) thickness and ganglion cell layer plus inner plexiform layer (GCIPL) thickness at the fovea in eyes affected with traumatic optic neuropathy (TON) compared with contralateral normal eyes, 2) to further evaluate these thicknesses within 3 weeks following trauma (defined as “early TON”), and 3) to investigate the relationship between these retinal layer thicknesses and visual function in TON eyes. Twenty-nine patients with unilateral TON were included. Horizontal and vertical spectral-domain optical coherence tomography (SD-OCT) scans of the fovea were taken in patients with unilateral TON. The main outcome measure was thickness of the entire retina, fRNFL, and GCIPL in eight areas. Thickness of each retinal layer was compared between affected and unaffected eyes. The correlation between the thickness of each retinal layer and visual function parameters, including best corrected visual acuity, color vision, P100 latency, and P100 amplitude in visual evoked potential (VEP), mean deviation (MD) and visual field index (VFI) in Humphrey visual field analysis in TON eyes was analyzed. Thicknesses of the entire retina, fRNFL, and GCIPL in SD-OCT were significantly thinner (3–36%) in all measurement areas of TON eyes compared to those in healthy eyes (all p<0.05). Whereas, only GCIPL in the outer nasal, superior, and inferior areas was significantly thinner (5–10%) in the early TON eyes than that in the control eyes (all p<0.01). A significant correlation was detected between retinal layer thicknesses and visual function parameters including color vision, P100 latency and P100 amplitude in VEP, MD, and VFI (particularly P100 latency, MD, and VFI) (r = -0.70 to 0.84). Among the retinal layers analyzed in this study, GCIPL (particularly in the superior and inferior areas) was most correlated with these five visual function parameters (r = -0.70 to 0.71). Therefore, evaluation of morphological

  14. [Adhesion of sealer cements to dentin with and without smear layer].

    PubMed

    Gettleman, B H; Messer, H H; ElDeeb, M E

    1991-01-01

    The influence of a smear layer on the adhesion of sealer cements to dentin was assessed in recently extracted human anterior teeth. A total of 120 samples was tested, 40 per sealer; 20 each with and without the smear layer. The teeth were split longitudinally, and the internal surfaces were ground flat. One-half of each tooth was left with the smear layer intact, while the other half had the smear removed by washing for 3 min with 17% EDTA followed by 5.25% NaOCI. Evidence of the ability to remove the smear layer was verified by scanning electron microscopy. Using a specially designed jig, the sealer was placed into a 4-mm wide x 4 mm deep well which was then set onto the tooth. PMID:1659858

  15. Surface effect on the magnetoelectric response of magnetoelectric layered composite with nanoscale thickness

    NASA Astrophysics Data System (ADS)

    Yu, GuoLiang; Zhang, HuaiWu

    2015-02-01

    A theoretical model is proposed to study the ME effect in the layered ME composite with nanoscale thickness, which taking into account the surface effect. The layered ME composites nano structure is treated as a bulk core plus two surface layers with zero thickness. The influence on the structure overall properties resulted from the surface effect is modeled by a spring force exerting on the boundary of the bulk core. Using the derived equations, the so-called effective Miller-Shenoy coefficient, static and electromechanical resonance (EMR) properties of the nanoscale thickness ME composite for the extensional-bending coupling deformations are analyzed theoretically. At the same time, the effect of the substrate on ME effect is theoretically studied by altering the thickness ratio of the substrate. Numerical results shows the effective properties and the static and EMR properties of the composites are size-dependent, and surface effect have non-ignored effects on the ME effect. Besides, the EMR frequency in nano-thickness composites are expected to occur at very low frequencies compared to nominal dimensional composites. The EMR frequency shows an increase with increasing substrate thickness, and predicts a maximum in the EMR ME coefficient at small but nonvanishing substrate thickness.

  16. Assessment of Layer Thickness and Interface Quality in CoP Electrodeposited Multilayers.

    PubMed

    Lucas, Irene; Ciudad, David; Plaza, Manuel; Ruiz-Gómez, Sandra; Aroca, Claudio; Pérez, Lucas

    2016-07-27

    The magnetic properties of CoP electrodeposited alloys can be easily controlled by layering the alloys and modulating the P content of the different layers by using pulse plating in the electrodeposition process. However, because of its amorphous nature, the study of the interface quality, which is a limitation for the optimization of the soft magnetic properties of these alloys, becomes a complex task. In this work, we use Rutherford backscattering spectroscopy (RBS) to determine that electrodeposited Co0.74P0.26/Co0.83P0.17 amorphous multilayers with layers down to 20 nm-thick are composed by well-defined layers with interfacial roughness below 3 nm. We have also determined, using magnetostriction measurements, that 4 nm is the lower limitation for the layer thickness. Below this thickness, the layers are mixed and the magnetic behavior of the multilayered films is similar to that shown by single layers, thus going from in-plane to out-of-plane magnetic anisotropy. Therefore, these results establish the range in which the magnetic properties of these alloys can be controlled by layering. PMID:27381897

  17. Adhesive strength of bioactive oxide layers fabricated on TNTZ alloy by three different alkali-solution treatments.

    PubMed

    Takematsu, E; Cho, K; Hieda, J; Nakai, M; Katsumata, K; Okada, K; Niinomi, M; Matsushita, N

    2016-08-01

    Bioactive oxide layers were fabricated on Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) by three different alkali solution treatments: hydrothermal (H), electrochemical (E), and hydrothermal-electrochemical (HE). The adhesive strength of the oxide layer to the TNTZ substrate was measured to determine whether this process achieves sufficient adhesive strength for implant materials. Samples subjected to the HE process, in which a current of 15mA/cm(2) was applied at 90°C for 1h (HE90-1h), exhibited a comparatively higher adhesive strength of approximately 18MPa while still maintaining a sufficiently high bioactivity. Based on these results, an oxide layer fabricated on TNTZ by HE90-1h is considered appropriate for practical biomaterial application, though thicker oxide layers with many cracks can lead to a reduced adhesive strength. PMID:26866453

  18. Focusing of dipole radiation by a negative index chiral layer. 1. A thick layer as compared with the wavelength

    SciTech Connect

    Guzatov, D V; Klimov, V V

    2014-09-30

    We have derived and investigated the analytical expressions for the fields of scattered radiation of an electric dipole source by a chiral (bi-isotropic) layer with arbitrary permittivity and permeability and arbitrary thickness. It is shown that in the negativeindex chiral layer the focus spot of dipole radiation is split due to excitation of right- and left-hand circularly polarised waves. The conditions are found under which the waves with one of the polarisations can be suppressed, which leads to a substantial improvement of the focusing properties of the chiral layer. (metamaterials)

  19. Variation of bone layer thicknesses and trabecular volume fraction in the adult male human calvarium.

    PubMed

    Boruah, Sourabh; Paskoff, Glenn R; Shender, Barry S; Subit, Damien L; Salzar, Robert S; Crandall, Jeff R

    2015-08-01

    The human calvarium is a sandwich structure with two dense layers of cortical bone separated by porous cancellous bone. The variation of the three dimensional geometry, including the layer thicknesses and the volume fraction of the cancellous layer across the population, is unavailable in the current literature. This information is of particular importance to mathematical models of the human head used to simulate mechanical response. Although the target geometry for these models is the median geometry of the population, the best attempt so far has been the scaling of a unique geometry based on a few median anthropometric measurements of the head. However, this method does not represent the median geometry. This paper reports the average three dimensional geometry of the calvarium from X-ray computed tomography (CT) imaging and layer thickness and trabecular volume fraction from micro CT (μCT) imaging of ten adult male post-mortem human surrogates (PMHS). Skull bone samples have been obtained and μCT imaging was done at a resolution of 30 μm. Monte Carlo simulation was done to estimate the variance in these measurements due to the uncertainty in image segmentation. The layer thickness data has been averaged over areas of 5mm(2). The outer cortical layer was found to be significantly (p < 0.01; Student's t test) thicker than the inner layer (median of thickness ratio 1.68). Although there was significant location to location difference in all the layer thicknesses and volume fraction measurements, there was no trend. Average distribution and the variance of these metrics on the calvarium have been shown. The findings have been reported as colormaps on a 2D projection of the cranial vault. PMID:25920690

  20. Prediction of Layer Thickness in Molten Borax Bath with Genetic Evolutionary Programming

    NASA Astrophysics Data System (ADS)

    Taylan, Fatih

    2011-04-01

    In this study, the vanadium carbide coating in molten borax bath process is modeled by evolutionary genetic programming (GEP) with bath composition (borax percentage, ferro vanadium (Fe-V) percentage, boric acid percentage), bath temperature, immersion time, and layer thickness data. Five inputs and one output data exist in the model. The percentage of borax, Fe-V, and boric acid, temperature, and immersion time parameters are used as input data and the layer thickness value is used as output data. For selected bath components, immersion time, and temperature variables, the layer thicknesses are derived from the mathematical expression. The results of the mathematical expressions are compared to that of experimental data; it is determined that the derived mathematical expression has an accuracy of 89%.

  1. Relaxation processes of a thick granular layer at seismic slip rates

    NASA Astrophysics Data System (ADS)

    Kuwano, O.; Nakatani, M.; Hatano, T.; Sakaguchi, H.

    2013-12-01

    We report on laboratory experiments designed to explore transient responses of a thick granular layer following a step change in slip velocity at seismic slip rates. Experiments were performed at constant normal stresses of 10-30kPa using a ring shear apparatus with inner/outer diameters of 15mm/25mm. We measure the friction coefficient and thickness of glass beads layer at sliding velocities between 0.5 and 3 m/s. Experimental results show that the friction coefficient and layer thickness suddenly increases/decrease as sudden increase/decrease of sliding velocity and then exponentially decay to new steady state with characteristic slip length. We found that characteristic slip length is of the order of 10m. The response to a velocity step decreases simply symmetric to that to a velocity step increase.

  2. Serum protein layers on parylene-C and silicon oxide: Effect on cell adhesion

    PubMed Central

    Delivopoulos, Evangelos; Ouberai, Myriam M.; Coffey, Paul D.; Swann, Marcus J.; Shakesheff, Kevin M.; Welland, Mark E.

    2015-01-01

    Among the range of materials used in bioengineering, parylene-C has been used in combination with silicon oxide and in presence of the serum proteins, in cell patterning. However, the structural properties of adsorbed serum proteins on these substrates still remain elusive. In this study, we use an optical biosensing technique to decipher the properties of fibronectin (Fn) and serum albumin adsorbed on parylene-C and silicon oxide substrates. Our results show the formation of layers with distinct structural and adhesive properties. Thin, dense layers are formed on parylene-C, whereas thicker, more diffuse layers are formed on silicon oxide. These results suggest that Fn acquires a compact structure on parylene-C and a more extended structure on silicon oxide. Nonetheless, parylene-C and silicon oxide substrates coated with Fn host cell populations that exhibit focal adhesion complexes and good cell attachment. Albumin adopts a deformed structure on parylene-C and a globular structure on silicon oxide, and does not support significant cell attachment on either surface. Interestingly, the co-incubation of Fn and albumin at the ratio found in serum, results in the preferential adsorption of albumin on parylene-C and Fn on silicon oxide. This finding is supported by the exclusive formation of focal adhesion complexes in differentiated mouse embryonic stem cells (CGR8), cultured on Fn/albumin coated silicon oxide, but not on parylene-C. The detailed information provided in this study on the distinct properties of layers of serum proteins on substrates such as parylene-C and silicon oxide is highly significant in developing methods for cell patterning. PMID:25555155

  3. Interrogating protonated/deuterated fibronectin fragment layers adsorbed to titania by neutron reflectivity and their concomitant control over cell adhesion

    PubMed Central

    McIntosh, Lisa; Whitelaw, Christine; Rekas, Agata; Holt, Stephen A.; van der Walle, Christopher F.

    2015-01-01

    The fibronectin fragment, 9th–10th-type III domains (FIII9–10), mediates cell attachment and spreading and is commonly investigated as a bioadhesive interface for implant materials such as titania (TiO2). How the extent of the cell attachment–spreading response is related to the nature of the adsorbed protein layer is largely unknown. Here, the layer thickness and surface fraction of two FIII9–10 mutants (both protonated and deuterated) adsorbed to TiO2 were determined over concentrations used in cell adhesion assays. Unexpectedly, the isotopic forms had different adsorption behaviours. At solution concentrations of 10 mg l−1, the surface fraction of the less conformationally stable mutant (FIII9′10) was 42% for the deuterated form and 19% for the protonated form (fitted to the same monolayer thickness). Similarly, the surface fraction of the more stable mutant (FIII9′10–H2P) was 34% and 18% for the deuterated and protonated forms, respectively. All proteins showed a transition from monolayer to bilayer between 30 and 100 mg l−1, with the protein longitudinal orientation moving away from the plane of the TiO2 surface at high concentrations. Baby hamster kidney cells adherent to TiO2 surfaces coated with the proteins (100 mg l−1) showed a strong spreading response, irrespective of protein conformational stability. After surface washing, FIII9′10 and FIII9′10–H2P bilayer surface fractions were 30/25% and 42/39% for the lower/upper layers, respectively, implying that the cell spreading response requires only a partial protein surface fraction. Thus, we can use neutron reflectivity to inform the coating process for generating bioadhesive TiO2 surfaces. PMID:25926699

  4. Effect of the regional variability of dentinal substrate and modes of application of adhesive systems on the mechanical properties of the adhesive layer

    PubMed Central

    Pupo, Yasmine Mendes; Michél, Milton Domingos; Gomes, Osnara Maria Mongruel; Lepienski, Carlos Maurício; Gomes, João Carlos

    2012-01-01

    Aim: This study assessed the effect of the dentin depth and the application mode on the hardness and elastic modulus of the adhesive layer. Materials and Methods: Occlusal surfaces of 48 caries-free human third molars were removed, at two levels: Superficial and deep dentin. For each type of surface, the test specimens were randomly divided into groups which underwent the application: A conventional two-step adhesive system (Adper™ Single Bond [SB]) and self-etch adhesives system (Adper™ SE Plus [SE] and AdheSE® [AD]). The adhesives applied were active or passive. Composite build-ups were constructed incrementally. The teeth were sectioned, embedded, and polished. The nanoindentation test was performed in the adhesive layer. The results were analyzed by ANOVA and Tukey tests. Results: In the adhesive layer, the higher hardness (0.307 ± 0.006 GPa) and elastic modulus (4.796 ± 0.165 GPa) of SE were obtained in superficial dentin in passive application. The elastic modulus of SE (4.115 ± 0.098 GPa) was lowest in active application in superficial dentin. The active application significantly increased the hardness of the SB in the deep dentin (0.011 ± 0.314 GPa) compared the superficial dentin (0.280 ± 0.010 GPa). For the AD, only the mode of application was statistically significant (P=0.0041) for the hardness, active application (0.289 ± 0.015 GPa) being higher than passive application (0.261 ± 0.013 GPa) (P=0.0042) in deep dentin. Conclusion: The experimental results reveal that the mechanical properties were influenced for the application mode of adhesive systems and dentin depth. PMID:22557810

  5. Mechanism for interfacial adhesion strength of an ion beam mixed Cu/polyimide with a thin buffer layer

    NASA Astrophysics Data System (ADS)

    Chang, G. S.; Chae, K. H.; Whang, C. N.; Kurmaev, E. Z.; Zatsepin, D. A.; Winarski, R. P.; Ederer, D. L.; Moewes, A.; Lee, Y. P.

    1999-01-01

    A Cu (400 Å)/Al (50 Å)/polyimide system showed larger adhesion strength than that of Cu (400 Å)/polyimide after N2+ ion beam mixing. X-ray emission spectroscopy was performed to elucidate the mechanism of adhesion enhancement of the ion beam mixed Cu (400 Å)/polyimide with a thin Al buffer layer. Cu L2,3 x-ray emission spectra showed the formation of a CuAl2O4 layer which is strongly correlated with the large adhesion strength of a Cu/Al/polyimide. A decrease in adhesion strength at an ion dose higher than 5×1015cm-2 was also explained by the formation of an amorphous carbon. This was understood by investigating C Kα x-ray emission spectra. The overall spectroscopic results were in accordance with the behavior of quantitative adhesion strength.

  6. Robustness of surface-enhanced Raman scattering substrate with a mercaptosilane adhesive layer for in vivo sensing applications

    NASA Astrophysics Data System (ADS)

    Okumura, Yasuaki; Jans, Hilde; van Dorpe, Pol; Li, Jiaqi; Minamiguchi, Masaru; Shioi, Masahiko; Vlaminck, Lieven; Lagae, Liesbet; Kawamura, Tatsuro

    2015-06-01

    A highly robust surface-enhanced Raman scattering (SERS) substrate for in vivo sensing applications is reported. In vivo sensing demands structurally robust substrates with good optical performance. SERS substrates containing gold nanostructures on SiO2 supports often suffer from a low adhesion strength of gold on SiO2. The proposed SERS substrate contains a mercaptosilane adhesive layer, which provides a high robustness without deteriorating the plasmon performance, in contrast to traditional titanium adhesive layers. The mercaptosilane-modified SERS substrate is sufficiently robust for in vivo sensing, as evidenced by its implantation in the animal skin for 2 months.

  7. Diurnal changes in retinal nerve fiber layer thickness with obstructive sleep apnea/hypopnea syndrome

    PubMed Central

    Chirapapaisan, Niphon; Likitgorn, Techawit; Pleumchitchom, Mintra; Sakiyalak, Darin; Banhiran, Wish; Saiman, Manatsawin; Chuenkongkaew, Wanicha

    2016-01-01

    AIM To compare the retinal nerve fiber layer (RNFL) thickness in the morning and evening in Thai patients with varying degrees of obstructive sleep apnea/hypopnea syndrome (OSAHS). METHODS In this cross-sectional study, potential OSAHS patients at Siriraj Hospital underwent polysomnography to determine the severity of OSAHS and an eye examination (including best corrected visual acuity, slit-lamp examination, and Goldmann applanation tonometry). RNFL thickness was recorded once in the morning and once in the evening, using spectral domain optical coherence tomography. Thickness was expressed as an average and given for each quadrant. Patients with ocular or systemic diseases that might affect RNFL thickness were excluded. RESULTS Forty-one eyes of 41 patients were classified into 4 OSAHS groups. The average and mean RNFL thickness in most of the four quadrants of the severe OSAHS group trended toward being less than those in the comparable quadrants of the other groups in both the morning and evening. In the moderate OSAHS group, the average RNFL thickness and temporal and superior quadrant thickness in the morning were significantly higher than in the evening (P=0.01, P=0.01, and P=0.03, respectively). In the severe OSAHS group, the inferior quadrant thickness in the morning was significantly higher than in the evening (P=0.03). CONCLUSION The RNFL thickness in the morning was higher than in the evening in moderate OSAHS. PMID:27500104

  8. Reduction in retinal nerve fiber layer thickness in young adults with autism spectrum disorders.

    PubMed

    Emberti Gialloreti, Leonardo; Pardini, Matteo; Benassi, Francesca; Marciano, Sara; Amore, Mario; Mutolo, Maria Giulia; Porfirio, Maria Cristina; Curatolo, Paolo

    2014-04-01

    Recent years have seen an increase in the use of retinal nerve fiber layer (RNFL) evaluation as an easy-to-use, reproducible, proxy-measure of brain structural abnormalities. Here, we evaluated RNFL thickness in a group of subjects with high functioning autism (HFA) or with Asperger Syndrome (AS) to its potential as a tool to study autism pathophysiology. All subjects underwent high-resolution spectral domain optical coherence tomography to evaluate RNFL thickness. HFA subjects presented with reduced global RNFL thickness compared both to AS subjects and controls. AS subjects showed a reduced nasal quadrant RNFL thickness compared to controls. Verbal-IQ/performance-IQ discrepancy correlated with RNFL thickness. Our data suggest that RNFL evaluation could help in the development of biological markers of autism pathophysiology. PMID:24014196

  9. Redefining electrical double layer thickness in narrow confinements: Effect of solvent polarization

    NASA Astrophysics Data System (ADS)

    Das, Siddhartha; Chakraborty, Suman; Mitra, Sushanta K.

    2012-05-01

    In this paper we delineate the consequences of field-dependent solvent polarization in the electric double layer (EDL) electrostatic potential distribution, and the effective EDL thickness in narrow nanofluidic confinements with thick (or overlapping) EDLs. The EDL, formed at the interface between a charged substrate and an electrolyte solution, induces a large electric field spanning across few nanometer distances from the interface. As a result, a polar solvent like water gets polarized, making its relative permittivity a function of the EDL electric field. This affects the overall EDL electrostatic potential distribution and most importantly, leads to a significant reduction of the effective EDL thickness, with the extent of the reduction being dictated by the value of field independent EDL thickness, strength of the solvent polarization, and the substrate-liquid interfacial electrostatic potential. Such a finding will necessitate redefining the classical EDL thickness, which will be of overwhelming significance in nanofluidic transport.

  10. Influence of an oxygen-inhibited layer on enamel bonding of dental adhesive systems: surface free-energy perspectives.

    PubMed

    Ueta, Hirofumi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Oouchi, Hajime; Sai, Keiichi; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2016-02-01

    The influence of an oxygen-inhibited layer (OIL) on the shear bond strength (SBS) to enamel and surface free-energy (SFE) of adhesive systems was investigated. The adhesive systems tested were Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to bovine enamel surfaces to determine the SBS, with and without an OIL, of adhesives. The SFE of cured adhesives with and without an OIL were determined by measuring the contact angles of three test liquids. There were no significant differences in the mean SBS of SM and CS specimens with or without an OIL; however, the mean SBS of SU specimens with an OIL was significantly higher than that of SU specimens without an OIL. For all three systems, the mean total SFE (γS), polarity force (γSp), and hydrogen bonding force (γSh) values of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The results of this study indicate that the presence of an OIL promotes higher SBS of a single-step self-etch adhesive system, but not of a three-step or a two-step self-etch primer system. The SFE values of cured adhesives with an OIL were significantly higher than those without an OIL. The SFE characteristics of the OIL of adhesives differed depending on the type of adhesive. PMID:26647775

  11. Micrometer-Thick Graphene Oxide-Layered Double Hydroxide Nacre-Inspired Coatings and Their Properties.

    PubMed

    Yan, You-Xian; Yao, Hong-Bin; Mao, Li-Bo; Asiri, Abdullah M; Alamry, Khalid A; Marwani, Hadi M; Yu, Shu-Hong

    2016-02-10

    Robust, functional, and flame retardant coatings are attractive in various fields such as building construction, food packaging, electronics encapsulation, and so on. Here, strong, colorful, and fire-retardant micrometer-thick hybrid coatings are reported, which can be constructed via an enhanced layer-by-layer assembly of graphene oxide (GO) nanosheets and layered double hydroxide (LDH) nanoplatelets. The fabricated GO-LDH hybrid coatings show uniform nacre-like layered structures that endow them good mechanic properties with Young's modulus of ≈ 18 GPa and hardness of ≈ 0.68 GPa. In addition, the GO-LDH hybrid coatings exhibit nacre-like iridescence and attractive flame retardancy as well due to their well-defined 2D microstructures. This kind of nacre-inspired GO-LDH hybrid thick coatings will be applied in various fields in future due to their high strength and multifunctionalities. PMID:26682698

  12. Controlled gentamicin release from multi-layered electrospun nanofibrous structures of various thicknesses.

    PubMed

    Sirc, Jakub; Kubinova, Sarka; Hobzova, Radka; Stranska, Denisa; Kozlik, Petr; Bosakova, Zuzana; Marekova, Dana; Holan, Vladimir; Sykova, Eva; Michalek, Jiri

    2012-01-01

    Polyvinyl alcohol nanofibers incorporating the wide spectrum antibiotic gentamicin were prepared by Nanospider™ needleless technology. A polyvinyl alcohol layer, serving as a drug reservoir, was covered from both sides by polyurethane layers of various thicknesses. The multilayered structure of the nanofibers was observed using scanning electron microscopy, the porosity was characterized by mercury porosimetry, and nitrogen adsorption/desorption measurements were used to determine specific surface areas. The stability of the gentamicin released from the electrospun layers was proved by high-performance liquid chromatography (HPLC) and inhibition of bacterial growth. Drug release was investigated using in vitro experiments with HPLC/MS quantification, while the antimicrobial efficacy was evaluated on Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. Both experiments proved that the released gentamicin retained its activity and showed that the retention of the drug in the nanofibers was prolonged with the increasing thickness of the covering layers. PMID:23071393

  13. Selective and non-selective deposition of thick polysilicon layers for adaptive mirror device

    NASA Astrophysics Data System (ADS)

    Bartek, M.; Vdovin, G. V.; Wolffenbuttel, R. F.

    1997-09-01

    Two IC-process-compatible fabrication schemes, based on the selective and non-selective deposition of a thick polysilicon layer in an epitaxial reactor, are used for adaptive micromirror device fabrication. The micromirror consists of a composite diaphragm (a 0960-1317/7/3/014/img1 square-shaped silicon nitride membrane on which an additional 0960-1317/7/3/014/img2 thick polycrystalline silicon layer with a circular aperture is formed) coated with a 0960-1317/7/3/014/img3 reflective aluminium layer on a bulk micromachined 10.5 mm by 10.5 mm square silicon frame. The additional polycrystalline silicon layer with a circular aperture improves the optical properties of a deflected square-shaped silicon nitride membrane resulting from anisotropic KOH etching.

  14. Thickness dependence of curvature, strain, and response time in ionic electroactive polymer actuators fabricated via layer-by-layer assembly

    NASA Astrophysics Data System (ADS)

    Montazami, Reza; Liu, Sheng; Liu, Yang; Wang, Dong; Zhang, Qiming; Heflin, James R.

    2011-05-01

    Ionic electroactive polymer (IEAP) actuators containing porous conductive network composites (CNCs) and ionic liquids can result in high strain and fast response times. Incorporation of spherical gold nanoparticles in the CNC enhances conductivity and porosity, while maintaining relatively small thickness. This leads to improved mechanical strain and bending curvature of the actuators. We have employed the layer-by-layer self-assembly technique to fabricate a CNC with enhanced curvature (0.43 mm-1) and large net intrinsic strain (6.1%). The results demonstrate that curvature and net strain of IEAP actuators due to motion of the anions increase linearly with the thickness of the CNC as a result of the increased volume in which the anions can be stored. In addition, after subtracting the curvature of a bare Nafion actuator without a CNC, it is found that the net intrinsic strain of the CNC layer is independent of thickness for the range of 20-80 nm, indicating that the entire CNC volume contributes equivalently to the actuator motion. Furthermore, the response time of the actuator due to anion motion is independent of CNC thickness, suggesting that traversal through the Nafion membrane is the limiting factor in the anion motion.

  15. Electrical resistivity of assembled transparent inorganic oxide nanoparticle thin layers: Influence of silica, insulating impurities and surfactant layer thickness

    PubMed Central

    Bubenhofer, Stephanie B.; Schumacher, Christoph M.; Koehler, Fabian M.; Luechinger, Norman A.; Sotiriou, Georgios A.; Grass, Robert N.; Stark, Wendelin J.

    2013-01-01

    Transparent, conductive layers prepared from nanoparticle dispersion of doped oxides are highly sensitive to impurities. Currently investigated cost efficient and fast production of thin conducting films for use in consumer electronics relies on wet processing such as spin and/or dip coating of surfactant-stabilized nanoparticle dispersions. This inherently results in entrainment of organic and inorganic impurities into the conducting layer leading to largely varying electrical conductivity. Therefore this study provides a systematic investigation on the effect of insulating surfactants, small organic molecules and silica in terms of pressure dependent electrical conductivity as a result of different core/shell structure (layer thickness). Application of high temperature flame synthesis gives access to antimony-doped tin oxide (ATO) nanoparticles with high purity. This well-defined starting material was then subjected to representative film preparation processes using organic additives. In addition ATO nanoparticles were prepared with a homogeneous inorganic silica layer (silica layer thickness from 0.7 to 2 nm). Testing both organic and inorganic shell materials for the electronic transport through the nanoparticle composite allowed a systematic study on the influence of surface adsorbates (e.g. organic, insulating materials on the conducting nanoparticle’s surface) in comparison to well-known insulators such as silica. Insulating impurities or shells revealed a dominant influence of tunneling effect on the overall layer resistance. Mechanical relaxation phenomena were found for 2 nm insulating shells for both large polymer surfactants and (inorganic) SiO2 shells. PMID:22545730

  16. Effects of accumulated film layers on the accuracy of quartz film thickness monitors

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.; Miller, W. E.

    1978-01-01

    The effect of accumulation layers on the accuracy of quartz thin-film thickness monitors is evaluated. Use of an expanded plane wave ultrasonic propagation theory correctly accounts for observed experimental data. The magnitude of the maximum errors calculated for simply reversing the order of a series of aluminum gold deposits is on the order of 5%. If one totally neglects intervening layers, multiple film propagation and nonlinearity can produce errors greater than 50%.

  17. On the meaning of the diffusion layer thickness for slow electrode reactions.

    PubMed

    Molina, A; González, J; Laborda, E; Compton, R G

    2013-02-21

    A key concept underpinning electrochemical science is that of the diffusion layer - the zone of depletion around an electrode accompanying electrolysis. The size of this zone can be found either from the simulated or measured concentration profiles (yielding the 'true' diffusion layer thickness) or, in the case of the Nernst ('linear') diffusion layer by extrapolating the concentration gradient at the electrode surface to the distance at which the concentration takes its bulk value. The latter concept is very well developed in the case of fast (so-called reversible) electrode processes, however the study of the linear diffusion layer has received scant attention in the case of slow charge transfer processes, despite its study being of great interest in the analysis of the influence of different experimental variables which determine the electrochemical response. Analytical explicit solutions for the concentration profiles, surface concentrations and real and linear diffusion layers corresponding to the application of a potential step to a slow charge transfer process are presented. From these expressions the dependence of the diffusion layer thickness on the potential, pulse time, heterogeneous rate constant and ratio of bulk concentrations of electroactive species and of diffusion coefficients is quantified. A profound influence of the reversibility degree of the charge transfer on the diffusion layer thickness is clear, showing that for non-reversible processes the real and linear diffusion layers reveal a minimum thickness which coincides with the equilibrium potential of the redox couple in the former case and with the reversible half-wave potential in the latter one. PMID:23301247

  18. Influence of thickness and permeability of endothelial surface layer on transmission of shear stress in capillaries

    NASA Astrophysics Data System (ADS)

    Zhang, SongPeng; Zhang, XiangJun; Tian, Yu; Meng, YongGang; Lipowsky, Herbert

    2015-07-01

    The molecular coating on the surface of microvascular endothelium has been identified as a barrier to transvascular exchange of solutes. With a thickness of hundreds of nanometers, this endothelial surface layer (ESL) has been treated as a porous domain within which fluid shear stresses are dissipated and transmitted to the solid matrix to initiate mechanotransduction events. The present study aims to examine the effects of the ESL thickness and permeability on the transmission of shear stress throughout the ESL. Our results indicate that fluid shear stresses rapidly decrease to insignificant levels within a thin transition layer near the outer boundary of the ESL with a thickness on the order of ten nanometers. The thickness of the transition zone between free fluid and the porous layer was found to be proportional to the square root of the Darcy permeability. As the permeability is reduced ten-fold, the interfacial fluid and solid matrix shear stress gradients increase exponentially two-fold. While the interfacial fluid shear stress is positively related to the ESL thickness, the transmitted matrix stress is reduced by about 50% as the ESL thickness is decreased from 500 to 100 nm, which may occur under pathological conditions. Thus, thickness and permeability of the ESL are two main factors that determine flow features and the apportionment of shear stresses between the fluid and solid phases of the ESL. These results may shed light on the mechanisms of force transmission through the ESL and the pathological events caused by alterations in thickness and permeability of the ESL.

  19. Lack of Correlation Between Diabetic Macular Edema and Thickness of the Peripapillary Retinal Nerve Fibre Layer

    PubMed Central

    Alkuraya, Hisham S.; Al-Gehedan, Saeed M.; Alsharif, Abdulrahman M.; Alasbali, Tariq; Lotfy, Nancy M.; Khandekar, Rajiv

    2016-01-01

    Introduction: We compared the thickness of the peripapillary retinal nerve fiber layer (RNFL) in patients with diabetic macular edema (DME) and/against the thickness in the normal population. Methods: This cross-sectional study compared the RNFL thickness in patients with DME (DME group) using optical coherence tomography (OCT) to a comparable group of healthy (nondiabetic) patients (control group). Measurements were performed in different/the four peripapillary quadrants and in the macula region for the fovea, parafoveal, and perifoveal areas. The mean RNFL thickness was compared between both groups. Results: There were fifty eyes of fifty nonglaucomatous diabetic patients with DME (29 with nonproliferative diabetic retinopathy [PDR] and 21 with PDR), and fifty eyes in the control group. The macular regions were significantly thicker in the DME group compared to the control group. The central foveal thickness was 149 μ thicker in eyes with DME compared to the control group (P < 0.001). The difference in total RNFL thickness between groups was not significant (4.4 μ [95% confidence interval: −3.1 to +12]). The between-group differences in peripapillary RNFL thickness by age group, glycemic control, history of intravitreal treatments, and refractive errors were not statistically significant (P > 0.05, all comparisons). Conclusion: Peripapillary RNFL thickness measurements were not significantly influenced by DME. Hence, OCT parameters could be used to monitor/early detect glaucomatous eyes even in the presence of DME. PMID:27555707

  20. Holographic Characteristics of an Acrylamide/Bisacrylamide Photopolymer in 40 1000 µm Thick Layers

    NASA Astrophysics Data System (ADS)

    Ortuño, M.; Gallego, S.; García, C.; Pascual, I.; Neipp, C.; Beléndez, A.

    2005-01-01

    In this study we analyze the holographic behaviour of an acrylamide/bisacrylamide photopolymer in layers that range in thickness from 40 to 1000 µm. The photopolymer is composed of acrylamide as polymerizable monomer, N,N' methylene-bis-acrylamide as crosslinker, triethanolamine as radical generator, yellowish eosin as sensitizer and polyvinyl alcohol as binder. The composition and method of depositing the solution varies depending on the desired thickness of the final layer. For each thickness we analyze the holographic behaviour of the material during recording of unslanted diffraction gratings using a continuous argon laser (514 nm) at an intensity of 5 mW/cm2. The response of the material is monitored in real time with an He-Ne laser. The results obtained for the different parameters evaluated vary considerably depends on the layer thickness. Therefore, the different potential applications of the material (fabrication of holographic optical elements, use as recording material in holographic interferometry, or manufacture of holographic memories) depends on its thickness.

  1. Thickness Considerations of Two-Dimensional Layered Semiconductors for Transistor Applications.

    PubMed

    Zhang, Youwei; Li, Hui; Wang, Haomin; Xie, Hong; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-01-01

    Layered two-dimensional semiconductors have attracted tremendous attention owing to their demonstrated excellent transistor switching characteristics with a large ratio of on-state to off-state current, Ion/Ioff. However, the depletion-mode nature of the transistors sets a limit on the thickness of the layered semiconductor films primarily determined by a given Ion/Ioff as an acceptable specification. Identifying the optimum thickness range is of significance for material synthesis and device fabrication. Here, we systematically investigate the thickness-dependent switching behavior of transistors with a wide thickness range of multilayer-MoS2 films. A difference in Ion/Ioff by several orders of magnitude is observed when the film thickness, t, approaches a critical depletion width. The decrease in Ion/Ioff is exponential for t between 20 nm and 100 nm, by a factor of 10 for each additional 10 nm. For t larger than 100 nm, Ion/Ioff approaches unity. Simulation using technical computer-aided tools established for silicon technology faithfully reproduces the experimentally determined scaling behavior of Ion/Ioff with t. This excellent agreement confirms that multilayer-MoS2 films can be approximated as a homogeneous semiconductor with high surface conductivity that tends to deteriorate Ion/Ioff. Our findings are helpful in guiding material synthesis and designing advanced field-effect transistors based on the layered semiconductors. PMID:27403803

  2. Thickness Considerations of Two-Dimensional Layered Semiconductors for Transistor Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Youwei; Li, Hui; Wang, Haomin; Xie, Hong; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-07-01

    Layered two-dimensional semiconductors have attracted tremendous attention owing to their demonstrated excellent transistor switching characteristics with a large ratio of on-state to off-state current, Ion/Ioff. However, the depletion-mode nature of the transistors sets a limit on the thickness of the layered semiconductor films primarily determined by a given Ion/Ioff as an acceptable specification. Identifying the optimum thickness range is of significance for material synthesis and device fabrication. Here, we systematically investigate the thickness-dependent switching behavior of transistors with a wide thickness range of multilayer-MoS2 films. A difference in Ion/Ioff by several orders of magnitude is observed when the film thickness, t, approaches a critical depletion width. The decrease in Ion/Ioff is exponential for t between 20 nm and 100 nm, by a factor of 10 for each additional 10 nm. For t larger than 100 nm, Ion/Ioff approaches unity. Simulation using technical computer-aided tools established for silicon technology faithfully reproduces the experimentally determined scaling behavior of Ion/Ioff with t. This excellent agreement confirms that multilayer-MoS2 films can be approximated as a homogeneous semiconductor with high surface conductivity that tends to deteriorate Ion/Ioff. Our findings are helpful in guiding material synthesis and designing advanced field-effect transistors based on the layered semiconductors.

  3. Thickness Considerations of Two-Dimensional Layered Semiconductors for Transistor Applications

    PubMed Central

    Zhang, Youwei; Li, Hui; Wang, Haomin; Xie, Hong; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-01-01

    Layered two-dimensional semiconductors have attracted tremendous attention owing to their demonstrated excellent transistor switching characteristics with a large ratio of on-state to off-state current, Ion/Ioff. However, the depletion-mode nature of the transistors sets a limit on the thickness of the layered semiconductor films primarily determined by a given Ion/Ioff as an acceptable specification. Identifying the optimum thickness range is of significance for material synthesis and device fabrication. Here, we systematically investigate the thickness-dependent switching behavior of transistors with a wide thickness range of multilayer-MoS2 films. A difference in Ion/Ioff by several orders of magnitude is observed when the film thickness, t, approaches a critical depletion width. The decrease in Ion/Ioff is exponential for t between 20 nm and 100 nm, by a factor of 10 for each additional 10 nm. For t larger than 100 nm, Ion/Ioff approaches unity. Simulation using technical computer-aided tools established for silicon technology faithfully reproduces the experimentally determined scaling behavior of Ion/Ioff with t. This excellent agreement confirms that multilayer-MoS2 films can be approximated as a homogeneous semiconductor with high surface conductivity that tends to deteriorate Ion/Ioff. Our findings are helpful in guiding material synthesis and designing advanced field-effect transistors based on the layered semiconductors. PMID:27403803

  4. Reduction in Retinal Nerve Fiber Layer Thickness in Young Adults with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Emberti Gialloreti, Leonardo; Pardini, Matteo; Benassi, Francesca; Marciano, Sara; Amore, Mario; Mutolo, Maria Giulia; Porfirio, Maria Cristina; Curatolo, Paolo

    2014-01-01

    Recent years have seen an increase in the use of retinal nerve fiber layer (RNFL) evaluation as an easy-to-use, reproducible, proxy-measure of brain structural abnormalities. Here, we evaluated RNFL thickness in a group of subjects with high functioning autism (HFA) or with Asperger Syndrome (AS) to its potential as a tool to study autism…

  5. Relationship between Retinal Layer Thickness and the Visual Field in Early Age-Related Macular Degeneration

    PubMed Central

    Acton, Jennifer H.; Smith, R. Theodore; Hood, Donald C.; Greenstein, Vivienne C.

    2012-01-01

    Purpose. To quantify and compare the structural and functional changes in subjects with early age-related macular degeneration (AMD), using spectral-domain optical coherence tomography (SD-OCT) and microperimetry. Methods. Twenty-one eyes of 21 subjects with early AMD were examined. MP-1 10-2 visual fields (VFs) and SD-OCT line and detail volume scans were acquired. The thicknesses of the outer segment (OS; distance between inner segment ellipsoid band and upper retinal pigment epithelium [RPE] border) and RPE layers and elevation of the RPE from Bruch's membrane were measured using a computer-aided manual segmentation technique. Thickness values were compared with those for 15 controls, and values at locations with VF total deviation defects were compared with values at nondefect locations at equivalent eccentricities. Results. Sixteen of 21 eyes with AMD had VF defects. Compared with controls, line scans showed significant thinning of the OS layer (P = 0.006) and thickening and elevation of the RPE (P = 0.037, P = 0.002). The OS layer was significantly thinner in locations with VF defects compared with locations without defects (P = 0.003). There was a negligible difference between the retinal layer thickness values of the 5 eyes without VF defects and the values of normal controls. Conclusions. In early AMD, when VF defects were present, there was significant thinning of the OS layer and thickening and elevation of the RPE. OS layer thinning was significantly associated with decreased visual sensitivity, consistent with known photoreceptor loss in early AMD. For AMD subjects without VF defects, thickness values were normal. The results highlight the clinical utility of both SD-OCT retinal layer quantification and VF testing in early AMD. PMID:23074210

  6. Effect of surface roughness and release layer on anti-adhesion performance of the imprint template

    NASA Astrophysics Data System (ADS)

    Duan, Yugang; Li, Yingjie; Ding, Yucheng; Li, Dichen

    2011-02-01

    UV imprint lithography has been initiated as an enabling, cost-effective technique to achieve 100 nm resolution patterning in recent years. However, the adhesion between resist and imprint template is one of the critical problems for the industrial application of imprint lithography. In this paper, two kinds of measures, including increase of surface roughness of template and application of a fluorinated release agent as self-assembled monolayers (SAMs) to the template surface, were taken to overcome the adhesion between resist and template. The test results of contact angle showed that the appropriate increase of surface roughness could improve hydrophilicity of template surface greatly, and improved the hydrophobicity of template surface when it was combined with self-assembled monolayers. The XPS, DRIR spectra indicated that the fluorinated release layers were successfully prepared on the surface of template using the process in the paper. The surface free energy of the template was 16.6 mN/m, and less than that of PTFE (18 mN/m). The imprint experiment results also showed that the anti-adhesion performance of treated template was improved greatly during detaching procedure, and the demolding force decreased by 56.64% in comparison with that of untreated template.

  7. Effect of Electrolyte Concentration on the Stern Layer Thickness at a Charged Interface.

    PubMed

    Brown, Matthew A; Goel, Alok; Abbas, Zareen

    2016-03-01

    The chemistry and physics of charged interfaces is regulated by the structure of the electrical double layer (EDL). Herein we quantify the average thickness of the Stern layer at the silica (SiO2 ) nanoparticle/aqueous electrolyte interface as a function of NaCl concentration following direct measurement of the nanoparticles' surface potential by X-ray photoelectron spectroscopy (XPS). We find the Stern layer compresses (becomes thinner) as the electrolyte concentration is increased. This finding provides a simple and intuitive picture of the EDL that explains the concurrent increase in surface charge density, but decrease in surface and zeta potentials, as the electrolyte concentration is increased. PMID:26880184

  8. Presence and function of a thick mucous layer rich in polysaccharides around Bacillus subtilis spores.

    PubMed

    Faille, Christine; Ronse, Annette; Dewailly, Etienne; Slomianny, Christian; Maes, Emmanuel; Krzewinski, Frédéric; Guerardel, Yann

    2014-01-01

    This study was designed to establish the presence and function of the mucous layer surrounding spores of Bacillus subtilis. First, an external layer of variable thickness and regularity was often observed on B. subtilis spores. Further analyses were performed on B. subtilis 98/7 spores surrounded by a thick layer. The mechanical removal of the layer did not affect their resistance to heat or their ability to germinate but rendered the spore less hydrophilic, more adherent to stainless steel, and more resistant to cleaning. This layer was mainly composed of 6-deoxyhexoses, ie rhamnose, 3-O-methyl-rhamnose and quinovose, but also of glucosamine and muramic lactam, known also to be a part of the bacterial peptidoglycan. The specific hydrolysis of the peptidoglycan using lysozyme altered the structure of the required mucous layer and affected the physico-chemical properties of the spores. Such an outermost mucous layer has also been seen on spores of B. licheniformis and B. clausii isolated from food environments. PMID:25115519

  9. Influence of bulk turbulence and entrance boundary layer thickness on the curved duct flow field

    NASA Technical Reports Server (NTRS)

    Crawford, R. A.

    1988-01-01

    The influence of bulk turbulence and boundary layer thickness on the secondary flow development in a square, 90 degree turning duct was investigated. A three-dimensional laser velocimetry system was utilized to measure the mean and fluctuating components of velocity at six cross-planes in the duct. The results from this investigation, with entrance boundary layer thickness of 20 percent, were compared with the thin boundary layer results documented in NASA CR-174811. The axial velocity profiles, cross-flow velocities, and turbulence intensities were compared and evaluated with regard to the influence of bulk turbulence intensity and boundary layer thickness, and the influence was significant. The results of this investigation expand the 90 degree curved duct experimental data base to higher turbulence levels and thicker entrance boundary layers. The experimental results provide a challenging benchmark data base for computational fluid dynamics code development and validation. The variation of inlet bulk turbulence intensity provides additional information to aid in turbulence model evaluation.

  10. Influences and interactions of inundation, peat, and snow on active layer thickness

    NASA Astrophysics Data System (ADS)

    Atchley, Adam L.; Coon, Ethan T.; Painter, Scott L.; Harp, Dylan R.; Wilson, Cathy J.

    2016-05-01

    Active layer thickness (ALT), the uppermost layer of soil that thaws on an annual basis, is a direct control on the amount of organic carbon potentially available for decomposition and release to the atmosphere as carbon-rich Arctic permafrost soils thaw in a warming climate. We investigate how key site characteristics affect ALT using an integrated surface/subsurface permafrost thermal hydrology model. ALT is most sensitive to organic layer thickness followed by snow depth but is relatively insensitive to the amount of water on the landscape with other conditions held fixed. The weak ALT sensitivity to subsurface saturation suggests that changes in Arctic landscape hydrology may only have a minor effect on future ALT. However, surface inundation amplifies the sensitivities to the other parameters and under large snowpacks can trigger the formation of near-surface taliks.

  11. Layer thickness and period as design parameters to tailor pyroelectric properties in ferroelectric superlattices

    SciTech Connect

    Misirlioglu, I. B.; Alpay, S. P.

    2014-10-27

    We theoretically examine the pyroelectric properties of ferroelectric-paraelectric superlattices as a function of layer thickness and configuration using non-linear thermodynamics coupled with electrostatic and electromechanical interactions between layers. We specifically study PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/SrTiO{sub 3} superlattices. The pyroelectric properties of such constructs consisting of relatively thin repeating units are shown to exceed the pyroelectric response of monolithic PbZr{sub 0.3}Ti{sub 0.7}O{sub 3} films. This is related to periodic internal electric fields generated due to the polarization mismatch between layers that allows tailoring of the shift in the transition temperature. Our results indicate that higher and electric field sensitive pyroresponse can be achieved from layer-by-layer engineered ferroelectric heterostructures.

  12. Retinal nerve fiber layer thickness in normal Indian pediatric population measured with optical coherence tomography.

    PubMed

    Pawar, Neelam; Maheshwari, Devendra; Ravindran, Meenakshi; Ramakrishnan, Renagappa

    2013-11-11

    Purpose: To measure the peripapillary retinal nerve fiber layer (RNFL) thickness in normal Indian pediatric population. Subjects and Methods: 120 normal Indian children ages 5-17 years presenting to the Pediatric Clinic were included in this observational cross-sectional study. RNFL thickness was measured with stratus optical coherence tomography (OCT). Children with strabismus or amblyopia, with neurological, metabolic, vascular, or other disorders and those with abnormal optic discs were excluded. One eye of each subject was randomly selected for statistical analysis. The effect of age, refraction and gender on RNFL thickness was investigated statistically. Result: OCT measurements were obtained in 120 of 130 (92.3%) subjects. Mean age was 10.8 ± 3.24 years (range 5-17). Average RNFL thickness was (± SD) 106.11 ± 9.5 μm (range 82.26-146.25). The RNFL was thickest inferiorly (134.10 ± 16.16 μm) and superiorly (133.44 ± 15.50 μm), thinner nasally (84.26 ± 16.43 μm), and thinnest temporally (70.72 ± 14.80 μm). In univariate regression analysis, age had no statistical significant effect on RNFL thickness (P = 0.7249) and refraction had a significant effect on RNFL thickness (P = 0.0008). Conclusion: OCT can be used to measure RNFL thickness in children. Refraction had an effect on RNFL thickness. In normal children, variation in RNFL thickness is large. The normative data provided by this study may assist in identifying changes in RNFL thickness in Indian children. PMID:24212231

  13. Correlation of Retinal Nerve Fiber Layer Thickness and Axial Length on Fourier Domain Optical Coherence Tomography

    PubMed Central

    Dhasmana, Renu; Nagpal, R.C.

    2016-01-01

    Introduction The assessment of the peripapillary Retinal Nerve Fiber Layer (RNFL) thickness has been an important tool for evaluating and diagnosing glaucoma and its progression. Literature suggests that myopic eyes are at an increased risk for developing glaucoma. This study gives an insight into the relationship of RNFL thickness to the axial length in normal population. Aim To correlate the RNFL thickness and the axial length in normal individuals with Fourier domain Optical Coherence Tomography (OCT). Materials and Methods In the current study, 298 eyes of 149 normal individuals (10 years or older) with or without refractive error were recruited. The RNFL thickness was measured using Optovue (RTVue) three-dimensional Fourier domain OCT. Results We observed an inverse relationship between average RNFL thickness and increasing axial length(p=0.003). Maximum RNFL thickness was seen in the Infero-Temporal (IT) quadrant and minimum in the Supero-Nasal (SN) quadrant. RNFL thickness did not show any tendency to decline with age using the Pearsons correlation (r=0.07). Females had an increased RNFL thickness in the Supero-Temporal (ST) and Infero-Nasal (IN) quadrant (p-value 0.046 and 0.02) in comparison to males. There was a statistically significant thinning in Ganglion Cell Complex (GCC) with increasing axial length (p-value 0.000) Conclusion The current study suggests that the average RNFL thickness does not decrease with age. The RNFL and GCC thickness shows an inverse correlation with axial length of the eyeball hence observations have to be carefully interpreted in myopic eyes. Clinicians need to keep the anatomical variations in RNFL for better patient management. PMID:27190850

  14. Choroidal Haller's and Sattler's Layer Thickness Measurement Using 3-Dimensional 1060-nm Optical Coherence Tomography

    PubMed Central

    Esmaeelpour, Marieh; Kajic, Vedran; Zabihian, Behrooz; Othara, Richu; Ansari-Shahrezaei, Siamak; Kellner, Lukas; Krebs, Ilse; Nemetz, Susanne; Kraus, Martin F.; Hornegger, Joachim; Fujimoto, James G.; Drexler, Wolfgang; Binder, Susanne

    2014-01-01

    Objectives To examine the feasibility of automatically segmented choroidal vessels in three-dimensional (3D) 1060-nmOCT by testing repeatability in healthy and AMD eyes and by mapping Haller's and Sattler's layer thickness in healthy eyes Methods Fifty-five eyes (from 45 healthy subjects and 10 with non-neovascular age-related macular degeneration (AMD) subjects) were imaged by 3D-1060-nmOCT over a 36°x36° field of view. Haller's and Sattler's layer were automatically segmented, mapped and averaged across the Early Treatment Diabetic Retinopathy Study grid. For ten AMD eyes and ten healthy eyes, imaging was repeated within the same session and on another day. Outcomes were the repeatability agreement of Haller's and Sattler's layer thicknesses in healthy and AMD eyes, the validation with ICGA and the statistical analysis of the effect of age and axial eye length (AL) on both healthy choroidalsublayers. Results The coefficients of repeatability for Sattler's and Haller's layers were 35% and 21% in healthy eyes and 44% and 31% in AMD eyes, respectively. The mean±SD healthy central submacular field thickness for Sattler's and Haller's was 87±56 µm and 141±50 µm, respectively, with a significant relationship for AL (P<.001). Conclusions Automated Sattler's and Haller's thickness segmentation generates rapid 3D measurements with a repeatability correspondingto reported manual segmentation. Sublayers in healthy eyes thinnedsignificantly with increasing AL. In the presence of the thinned Sattler's layer in AMD, careful measurement interpretation is needed. Automatic choroidal vascular layer mapping may help to explain if pathological choroidal thinning affects medium and large choroidal vasculature in addition to choriocapillaris loss. PMID:24911446

  15. Prospective Study on Retinal Nerve Fibre Layer Thickness Changes in Isolated Unilateral Retrobulbar Optic Neuritis

    PubMed Central

    Yau, Gordon S. K.; Lee, Jacky W. Y.; Lau, Patrick P. K.; Tam, Victor T. Y.; Wong, Winnie W. Y.; Yuen, Can Y. F.

    2013-01-01

    Purpose. To investigate the retinal nerve fibre layer (RNFL) thickness after unilateral acute optic neuritis using optical coherence tomography (OCT). Patients and Methods. This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis. RNFL thickness and visual acuity (VA) of the attack and normal fellow eye were measured at presentation and 3 months in both the treatment and nontreatment groups. Results. 11 subjects received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eye (P ≥ 0.4). At 3 months, the attack eye had a thinner temporal (P = 0.02) and average (P = 0.05) RNFL compared to the fellow eye. At 3 months, the attack eye had significant RNFL thinning in the 4 quadrants and average thickness (P ≤ 0.0002) compared to baseline. The RNFL thickness between the treatment and nontreatment groups was similar at baseline and 3 months (P ≥ 0.1). Treatment offered better VA at 3 months (0.1 ± 0.2 versus 0.3 ± 0.2 LogMAR, P = 0.04). Conclusion. Generalized RNFL thinning occurred at 3 months after a first episode of acute optic neuritis most significantly in the temporal quadrant and average thickness. Visual improvement with treatment was independent of RNFL thickness. PMID:24459442

  16. Microfluidic adhesion induced by subsurface microstructures.

    PubMed

    Majumder, Abhijit; Ghatak, Animangsu; Sharma, Ashutosh

    2007-10-12

    Natural adhesives in the feet of different arthropods and vertebrates show strong adhesion as well as excellent reusability. Whereas the hierarchical structures on the surface are known to have a substantial effect on adhesion, the role of subsurface structures such as the network of microchannels has not been studied. Inspired by these bioadhesives, we generated elastomeric layers with embedded air- or oil-filled microchannels. These adhesives showed remarkable enhancement of adhesion ( approximately 30 times), which results from the crack-arresting properties of the microchannels, together with the surface stresses caused by the capillary force. The importance of the thickness of the adhesive layer, channel diameter, interchannel spacing, and vertical position within the adhesive has been examined for developing an optimal design of this microfluidic adhesive. PMID:17932295

  17. Effect of smear layer treatment on dentin bond of self-adhesive cements.

    PubMed

    Kambara, Keisuke; Nakajima, Masatoshi; Hosaka, Keiichi; Takahashi, Masahiro; Thanatvarakorn, Ornnicha; Ichinose, Shizuko; Foxton, Richard M; Tagami, Junji

    2012-01-01

    The purpose of this study was to compare the dentin bond strength of three self-adhesive cements with smear layer pretreatments using a calcium-chelating agent (EDTA) and deproteinizing solution (NaOCl) and to evaluate their interfacial characteristics. Smear layer-covered dentin surfaces were pretreated with EDTA for 60 s, NaOCl for 5 and 15 s, or none. Three self-adhesive cements; Clearfil SA luting (Kuraray Medical), Rely X Unicem clicker (3M ESPE) and Breeze (Pentron) were applied to the dentin surfaces. After 24-h water storage, shear bond strengths to dentin were determined. In addition, nanoleakage evaluation at the interface was performed using FE-SEM and EDS. EDTA-pretreatment significantly improved the bond strength of BR (p<0.05) and NaOCl-pretreatment for 15 s significantly improved the bond strength of RX (p<0.05). On the other hand, for SA, both pretreatments significantly decreased bond strength to dentin (p<0.05). Nanoleakage formation was observed in various amounts at the cement-dentin interfaces. PMID:23207204

  18. Electrochemical layer-by-layer approach to fabricate mechanically stable platinum black microelectrodes using a mussel-inspired polydopamine adhesive

    NASA Astrophysics Data System (ADS)

    Kim, Raeyoung; Nam, Yoonkey

    2015-04-01

    Objective. Platinum black (PtBK) has long been used for microelectrode fabrication owing to its high recording performance of neural signals. The porous structure of PtBK enlarges the surface area and lowers the impedance, which results in background noise reduction. However, the brittleness of PtBK has been a problem in practice. In this work, we report mechanically stable PtBK microelectrodes using a bioinspired adhesive film, polydopamine (pDA), while maintaining the low impedance of PtBK. Approach. The pDA layer was incorporated into the PtBK structure through electrochemical layer-by-layer deposition. Varying the number of layers and the order of materials, multi-layered pDA-PtBK hybrids were fabricated and the electrical properties, both impedance and charge injection limit, were evaluated. Main results. Multilayered pDA-PtBK hybrids had electrical impedances as low as PtBK controls and charge injection limit twice larger than controls. For the 30 min-ultrasonication agitation test, impedance levels rarely changed for some of the pDA-PtBK hybrids indicating that the pDA improved the mechanical property of the PtBK structures. The pDA-PtBK hybrid microelectrodes readily recorded neural signals of cultured hippocampal neurons, where background noise levels and signal-to-noise were 2.43 ∼ 3.23 μVrms and 28.4 ∼ 69.1, respectively. Significance. The developed pDA-PtBK hybrid microelectrodes are expected to be applicable to neural sensors for neural prosthetic studies.

  19. Hydrodynamic thickness of petroleum oil adsorbed layers in the pores of reservoir rocks.

    PubMed

    Alkafeef, Saad F; Algharaib, Meshal K; Alajmi, Abdullah F

    2006-06-01

    The hydrodynamic thickness delta of adsorbed petroleum (crude) oil layers into the pores of sandstone rocks, through which the liquid flows, has been studied by Poiseuille's flow law and the evolution of (electrical) streaming current. The adsorption of petroleum oil is accompanied by a numerical reduction in the (negative) surface potential of the pore walls, eventually stabilizing at a small positive potential, attributed to the oil macromolecules themselves. After increasing to around 30% of the pore radius, the adsorbed layer thickness delta stopped growing either with time or with concentrations of asphaltene in the flowing liquid. The adsorption thickness is confirmed with the blockage value of the rock pores' area determined by the combination of streaming current and streaming potential measurements. This behavior is attributed to the effect on the disjoining pressure across the adsorbed layer, as described by Derjaguin and Churaev, of which the polymolecular adsorption films lose their stability long before their thickness has approached the radius of the rock pore. PMID:16414057

  20. Influence of emissive layer thickness on electrical characteristics of polyfluorene copolymer based polymer light emitting diodes

    NASA Astrophysics Data System (ADS)

    Das, D.; Gopikrishna, P.; Singh, A.; Dey, A.; Iyer, P. K.

    2016-04-01

    Polymer light emitting diodes (PLEDs) with a device configuration of ITO/PEDOT:PSS/PFONPN01 [Poly [2,7-(9,9’-dioctylfluorene)-co-N-phenyl-1,8-naphthalimide (99:01)]/LiF/Al have been fabricated by varying the emissive layer (EML) thickness (40/65/80/130 nm) and the influence of EML thickness on the electrical characteristics of PLED has been studied. PLED can be modelled as a simple combination of resistors and capacitors. The impedance spectroscopy analysis showed that the devices with different EML thickness had different values of parallel resistance (RP) and the parallel capacitance (CP). The impedance of the devices is found to increase with increasing EML thickness resulting in an increase in the driving voltage. The device with an emissive layer thickness of 80nm, spin coated from a solution of concentration 15 mg/mL is found to give the best device performance with a maximum brightness value of 5226 cd/m2.

  1. Influence of liquid-layer thickness on pulmonary surfactant spreading and collapse.

    PubMed

    Siebert, Trina A; Rugonyi, Sandra

    2008-11-15

    Pulmonary surfactant spreads on the thin ( approximately 0.1 microm) liquid layer that lines the alveoli, forming a film that reduces surface tension and allows normal respiration. Pulmonary surfactant deposited in vitro on liquid layers that are several orders of magnitude thicker, however, does not reach the low surface tensions ( approximately 0.001 N/m) achieved in the lungs during exhalation when the surfactant film compresses. This is due to collapse, a surface phase transition during which the surfactant film, rather than decreasing surface tension by increasing its surface density, becomes thicker at constant surface tension ( approximately 0.024 N/m). Formation of the collapse phase requires transport of surfactant to collapse sites, and this transport can be hindered in thinner liquid layers by viscous resistance to motion. Our objective is to determine the effect of the liquid-layer thickness on surfactant transport, which might affect surfactant collapse. To this end, we developed a mathematical model that accounts for the effect of the liquid-layer thickness on surfactant transport, and focused on surfactant spreading and collapse. Model simulations showed a marked decrease in collapse rates for thinner liquid layers, but this decrease was not enough to completely explain differences in surfactant film behavior between in vitro and in situ experiments. PMID:18676658

  2. Leaping shampoo glides on a 500-nm-thick lubricating air layer

    NASA Astrophysics Data System (ADS)

    Li, Erqiang; Lee, Sanghyun; Marston, Jeremy; Bonito, Andrea; Thoroddsen, Sigurdur

    2013-11-01

    When a stream of shampoo is fed onto a pool in one's hand, a jet can leap sideways or rebound from the liquid surface in an intriguing phenomenon known as the Kaye effect. Earlier studies have debated whether non-Newtonian effects are the underlying cause of this phenomenon, making the jet glide on top of a shear-thinning liquid layer, or whether an entrained air layer is responsible. Herein we show unambiguously that the jet slides on a lubricating air layer [Lee et al., Phys. Rev. E 87, 061001 (2013)]. We identify this layer by looking through the pool liquid and observing its rupture into fine micro-bubbles. The resulting micro-bubble sizes suggest that the thickness of this air layer is around 500 nm. This thickness estimate is also supported by the tangential deceleration of the jet during the rebounding, with the shear stress within the thin air layer sufficient for the observed deceleration. Particle tracking within the jet shows uniform velocity, with no pronounced shear, which would be required for shear-thinning effects. The role of the surfactant may primarily be to stabilize the air film.

  3. Quantification of photoreceptor layer thickness in different macular pathologies using ultrahigh-resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Drexler, Wolfgang; Hermann, Boris; Unterhuber, Angelika; Sattmann, Harald; Wirtitsch, Matthias; Stur, Michael; Scholda, Christoph; Ergun, Erdem; Anger, Elisabeth; Ko, Tony H.; Schubert, Christian; Ahnelt, Peter K.; Fujimoto, James G.; Fercher, Adolf F.

    2004-07-01

    In vivo ultrahigh resolution ophthalmic OCT has been performed in more than 300 eyes of 200 patients with several retinal pathologies, demonstrating unprecedented visualization of all major intraretinal layers, in particular the photoreceptor layer. Visualization as well as quantification of the inner and outer segment of the photoreceptor layer especially in the foveal region has been acvhieved. In normal subjects the photoreceptor layer thickness in the center of the fovea is about of 90 μm, approximately equally distributed to the inner and the outer photoreceptor segment. In the parafoveal region this thickness is reduced to ~50 μm (~30 μm for the inner and ~20 μm for the outer segment). This is in good agreement with well known increase of cone outer segments in the central foveal region. Photoreceptor layer impairment in different macular pathologies like macular hole, central serous chorioretinopathy, age related macular degeneration, foveomacular dystrophies, Stargardt dystrophy as well as retinitis pigmentosa has been investigated. Photoreceptor layer loss significantly correlated with visual acuity (R2 = 0.6, p < 0.001) and microperimetry findings for the first time in 22 eyes with Stargardt dystrophy. Visualization and quantification of photoreceptor inner and outer segment using ultrahigh resolution OCT has the potential to improve early ophthalmic diagnosis, contributes to a better understanding of pathogenesis of retinal diseases as well as might have impact in the development and monitoring of novel therapy approaches.

  4. Influence of homo buffer layer thickness on the quality of ZnO epilayers.

    PubMed

    Eid, E A; Fouda, A N

    2015-10-01

    ZnO buffer layers with different thicknesses were deposited on a-plane sapphire substrates at 300 °C. ZnO epilayers were grown on ZnO buffers at 600 °C by radio-frequency magnetron sputtering and vacuum annealed at 900 °C for an hour. Influence of nucleation layer thickness on the structural and quality of ZnO thin films was investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and Raman spectroscopy. The best ZnO film quality was obtained with the ZnO buffer layer of 45 nm thick which provided the smoothest surface with RMS value of 0.3 nm. X-ray diffraction measurements reveal that the films have a single phase wurtzite structure with (0001) preferred crystal orientation. As evident from narrow FWHM of ZnO (0002) rocking curve, ZnO buffer can serve as a good template for the growth of high-quality ZnO films with little tilt. In addition, the micro-Raman scattering measurements at room temperature revealed the existence of Raman active phonon modes of ZnO; A1(TO), A1(LO) and E2(high). The latter two modes were not observed in thin buffer layer beside the dis-appearance of E2(low) mode in all films. PMID:25950638

  5. Thickness effect of catalyst layer on silicon nanowires morphology and features

    NASA Astrophysics Data System (ADS)

    Hamidinezhad, Habib

    2016-02-01

    Silicon nanowires (SiNWs) have been synthesized on gold layer-coated silicon substrates via plasma enhanced chemical vapor deposition method (PECVD). Various thicknesses of Au layers were coated on Si (111) substrates using radio frequency magnetron sputtering. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to characterize the morphology, compositions, and structures of the samples. The results show that the sample consisted of single-crystalline SiNWs with the diameters ranging from 40 to 160 nm and length up to 3 μm. It was observed that the diameter of SiNWs increases with increasing of Au catalyst layers thickness. Raman spectra display peaks with narrow and asymmetric shape at 518 cm-1 for the SiNWs, indicating the high crystalline nature of the samples. A possible growth mechanism is proposed for the formation of nanowires (NWs). It has been found that the features of SiNWs depend on the thickness of Au layers.

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

    PubMed

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

    2016-06-22

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

  7. Retinal Nerve Fiber Layer Thickness Measurement Comparison Using Spectral Domain and Swept Source Optical Coherence Tomography

    PubMed Central

    Ha, Ahnul; Lee, Seung Hyen; Lee, Eun Ji

    2016-01-01

    Purpose To investigate the retinal nerve fiber layer (RNFL) thickness concordance when measured by spectral domain (SD) and swept source (SS) optical coherence tomography (OCT), and to compare glaucoma-discriminating capability. Methods RNFL thicknesses were measured with the scan circle, centered on the optic nerve head, in 55 healthy, 41 glaucoma suspected, and 87 glaucomatous eyes. The RNFL thickness measured by the SD-OCT (sdRNFL thickness) and SS-OCT (ssRNFL thickness) were compared using the t-test. Bland-Altman analysis was performed to examine their agreement. We compared areas under the receiver operating characteristics curve and examined sdRNFL and ssRNFL thickness for discriminating glaucomatous eyes from healthy eyes, and from glaucoma suspect eyes. Results The average ssRNFL thickness was significantly greater than sdRNFL thickness in healthy (110.0 ± 7.9 vs. 100.1 ± 6.8 µm, p < 0.001), glaucoma suspect (96.8 ± 9.3 vs. 89.6 ± 7.9 µm, p < 0.001), and glaucomatous eyes (74.3 ± 14.2 vs. 69.1 ± 12.4 µm, p = 0.011). Bland-Altman analysis showed that there was a tendency for the difference between ssRNFL and sdRNFL to increase in eyes with thicker RNFL. The area under the curves of the average sdRNFL and ssRNFL thickness for discriminating glaucomatous eyes from healthy eyes (0.984 vs. 0.986, p = 0.491) and glaucoma suspect eyes (0.936 vs. 0.918, p = 0.132) were comparable. Conclusions There was a tendency for ssRNFL thickness to increase, compared with sdRNFL thickness, in eyes with thicker RNFL. The ssRNFL thickness had comparable diagnostic capability compared with sdRNFL thickness for discriminating glaucomatous eyes from healthy eyes and glaucoma suspect eyes. PMID:27051263

  8. Lidar Descriptions of Mixing-Layer Thickness Characteristics in a Complex Terrain/Coastal Environment.

    NASA Astrophysics Data System (ADS)

    McElroy, James L.; Smith, Ted B.

    1991-05-01

    Airborne lidar and supplementary measurements made during a major study of air chemistry in southern California (SCCCAMP 1985) provided a rare opportunity to examine atmospheric boundary-layer structure in a coastal area with complex terrain. This structure results from a combination of daytime heating or convection in the boundary layer (CBL), the intrusion of a marine layer into the inland areas, the thermal internal boundary layer (TIBL) formed within the marine onshore flow, inland growth of the TIBL, interactions of the CBL and the TIBL, and airflow interactions with terrain features.Measurements showed offshore mixing-layer thicknesses during SCCCAMP to be quite uniform spatially and day to day at 100-200 m. Movement of this layer onshore occurred readily with terrain that sloped gradually upward (e.g., to 300 m MSL at 50 km inland), but was effectively blocked by a 400-500 m high coastal ridge. In the higher terrain beyond the coastal ridge, aerosol layers aloft were often created as a result of deep convection and of a combination of onshore flow and heated, upslope airflow activity. Such aerosol layers can extend far offshore when embedded in reverse circulations aloft.The forward boundary of the marine layer was quite sharp, resembling a miniature cold front. Within the marine layer the onshore flow initiates a TIBL at the coastline, which increases in depth with distance inland due to roughness and convective influences. A coherent marine layer with imbedded TIBL was maintained for inland distances of 20-50 km, depending on terrain. Intense heating occurred inland prior to the arrival and undercutting by the marine front. The resulting, effective mixing layer increased in thickness from a few hundred meters to nearly two kilometers in a very short distance.Comparisons of a representative, physically based TIBL and convective mixing-layer models with observed data indicate that they generally do a credible job of estimating the depth of the marine layer

  9. Influence of electron transport layer thickness on optical properties of organic light-emitting diodes

    SciTech Connect

    Liu, Guohong; Liu, Yong; Li, Baojun; Zhou, Xiang

    2015-06-07

    We investigate experimentally and theoretically the influence of electron transport layer (ETL) thickness on properties of typical N,N′-diphenyl-N,N′-bis(1-naphthyl)-[1,1′-biphthyl]-4,4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}) heterojunction based organic light-emitting diodes (OLEDs), where the thickness of ETL is varied to adjust the distance between the emitting zone and the metal electrode. The devices showed a maximum current efficiency of 3.8 cd/A when the ETL thickness is around 50 nm corresponding to an emitter-cathode distance of 80 nm, and a second maximum current efficiency of 2.6 cd/A when the ETL thickness is around 210 nm corresponding to an emitter-cathode distance of 240 nm. We adopt a rigorous electromagnetic approach that takes parameters, such as dipole orientation, polarization, light emitting angle, exciton recombination zone, and diffusion length into account to model the optical properties of devices as a function of varying ETL thickness. Our simulation results are accurately consistent with the experimental results with a widely varying thickness of ETL, indicating that the theoretical model may be helpful to design high efficiency OLEDs.

  10. Aerodynamically-driven condensate layer thickness distributions on isothermal cylindrical surfaces

    NASA Technical Reports Server (NTRS)

    Rosner, D. E.; Gunes, D.; Nazih-Anous, N.

    1983-01-01

    A simple yet rather general mathematical model is presented for predicting the distribution of condensate layer thickness when aerodynamic shear is the dominant mechanism of liquid flow along the surface. The Newtonian condensate film is treated using well-known thin-layer (lubrication theory) approximations, and condensate supply is taken to be the result of either convective diffusion or inertial impaction. Illustrative calculations for a circular cylinder in a crossflow at Re = 100,000 reveal the consequences of alternate condensate arrival mechanisms and the existence of thicker reverse-flow films behind the position of gas boundary-layer separation. The present formulation is readily generalized to include transient liquid layer flows on noncircular objects of variable surface temperature, as encountered in turbine-blade materials testing or operation.

  11. Measurement and correlation of aerodynamic heating to surface corrugation stiffened structures in thick turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Brandon, H. J.; Masek, R. V.

    1974-01-01

    The flow conditions for which heating distributions were measured on corrugated surfaces and wavy walls in turbulent boundary layers are shown, along with the ratio of the displacement thickness to the roughness height versus the local edge Mach number for an equivalent smooth surface. The present data are seen to greatly extend the range of data available on corrugated surfaces in turbulent boundary layers. These data were obtained by testing fullscale corrugation roughened panels in the wall boundary layer of a supersonic and hypersonic wind tunnel. The experimental program used to obtain the data is described. The data are analyzed and correlated in terms of the pertinent flow and geometric parameters. The developed correlations are compared with the available thin boundary layer data, as well as with previously published correlation techniques.

  12. Improved performance of P-type DSCs with a compact blocking layer coated by different thicknesses

    NASA Astrophysics Data System (ADS)

    Ho, Phuong; Bao, Le Quoc; Cheruku, Rajesh; Kim, Jae Hong

    2016-07-01

    The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells (p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency (η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

  13. Fabrication of microfluidic chips using lithographic patterning and adhesive bonding of the thick negative photoresist AZ 125 nXT

    NASA Astrophysics Data System (ADS)

    Knoll, Thorsten; Bergmann, Andreas; Nußbaum, Dominic

    2015-05-01

    In this work, for the first time the negative photoresist AZ 125 nXT was used for the fabrication of a microfluidic chip. Usually, fabrication of microfluidic devices on the basis of silicon or glass substrates is done by using the epoxy-based negative photoresist SU-8 or other thick film polymer materials. The suitability of SU-8 for various microfluidic applications has been shown in the fields of bioanalytic devices, lab-on-chip systems or microreaction technology. However, processing is always a very challenging task with regard to the adaptation of process parameters to the individual design and required functionality. Now, the AZ 125 nXT allows for the fabrication of structures in a wide thickness range with only one type of viscosity. In contrast to SU-8, the AZ 125 nXT is fully cross-linked during UV exposure and does not require a time-consuming post-exposure bake. 90 μm deep microfluidic channels were defined by lithographic patterning of AZ 125 nXT. Sealing of the open microfluidic channels was performed by a manual adhesive bonding process at a temperature of 100 °C. The fluidic function was successfully tested with flow rates up to 20 ml/min by means of a microfluidic edge connector. Long term stability and chemical resistance of the fabricated microfluidic channels will be investigated in the near future. The presented work shows the potential of AZ 125 nXT as a possible alternative to SU-8 for the fabrication of microfluidic chips.

  14. Thick growing multilayer nanobrick wall thin films: super gas barrier with very few layers.

    PubMed

    Guin, Tyler; Krecker, Michelle; Hagen, David Austin; Grunlan, Jaime C

    2014-06-24

    Recent work with multilayer nanocoatings composed of polyelectrolytes and clay has demonstrated the ability to prepare super gas barrier layers from water that rival inorganic CVD-based films (e.g., SiOx). In an effort to reduce the number of layers required to achieve a very low oxygen transmission rate (OTR (<0.01 cc/m(2)·day·atm)) in these nanocoatings, buffered cationic chitosan (CH) and vermiculite clay (VMT) were deposited using layer-by-layer (LbL) assembly. Buffering the chitosan solution and its rinse with 50 mM Trizma base increased the thickness of these films by an order of magnitude. The OTR of a 1.6-μm-thick, six-bilayer film was 0.009 cc/m(2)·day·atm, making this the best gas barrier reported for such a small number of layers. This simple modification to the LbL process could likely be applied more universally to produce films with the desired properties much more quickly. PMID:24914613

  15. Wire or no wire-Depends on the catalyst layer thickness

    NASA Astrophysics Data System (ADS)

    Li, Feng Ji; Zhang, Sam; Lee, Jyh-Wei; Zhao, Dongliang

    2013-10-01

    Crystalline silicon (Si) nanowire could be directly grown from Si wafer upon thermal annealing in the presence of catalyst such as gold (Au). However, the role of the catalyst layer thickness is yet elucidated. In this work, 10 nm, 20 nm, and 40 nm Au layers were respectively sputtered on Si wafer substrates, followed by 2 min thermal annealing at 1000 °C under Ar atmosphere, to find the relationship between the catalyst layer thickness and formation of the nanowire. Results show that in the case of thin layer of catalyst, crystalline-Si/amorphous-SiOx coaxial nanowires grew. But with thicker layers of catalyst, no wires were found but crystalline Au particles capsulated with amorphous SiOx. The catalyst and nanowire morphologies and structures were carefully examined through a scanning electron microscope, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy and selected area diffraction. A model is developed to explain the formation mechanism of the Si/SiOx and Au/SiOx core-shell nanostructures.

  16. Influence of the layer thickness in plasmonic gold nanoparticles produced by thermal evaporation

    PubMed Central

    Gaspar, D.; Pimentel, A. C.; Mateus, T.; Leitão, J. P.; Soares, J.; Falcão, B. P.; Araújo, A.; Vicente, A.; Filonovich, S. A.; Águas, H.; Martins, R.; Ferreira, I.

    2013-01-01

    Metallic nanoparticles (NPs) have received recently considerable interest of photonic and photovoltaic communities. In this work, we report the optoelectronic properties of gold NPs (Au-NPs) obtained by depositing very thin gold layers on glass substrates through thermal evaporation electron-beam assisted process. The effect of mass thickness of the layer was evaluated. The polycrystalline Au-NPs, with grain sizes of 14 and 19 nm tend to be elongated in one direction as the mass thickness increase. A 2 nm layer deposited at 250°C led to the formation of Au-NPs with 10-20 nm average size, obtained by SEM images, while for a 5 nm layer the wide size elongates from 25 to 150 nm with a mean at 75 nm. In the near infrared region was observed an absorption enhancement of amorphous silicon films deposited onto the Au-NPs layers with a corresponding increase in the PL peak for the same wavelength region. PMID:23552055

  17. Designed drug-release systems having various breathable polyurethane film-backed hydrocolloid acrylated adhesive layers for moisture healing.

    PubMed

    Chang, Ching-Hsien; Liu, Hsia-Wei; Huang, Ching-Cheng

    2014-01-01

    A series of designed drug-release systems were prepared and established for clear moisture healing. These systems were designed to have an interpenetrating polymer network (IPN) structure, which contained a breathable polyurethane film, hydrocolloidlayer, and polyacrylate adhesive layer. Breathable polyurethane film (2000 g/m(2)/24 hr) with high moisture permeability was employed as a base for new drug-release systems or wound dressings. All drug-release systems having a polyurethane film-backed hydrocolloid acrylated adhesive layer showed an increase of water uptakes with increasing time. After 114 hours, high water uptakes of drug-release systems with 20% hydrocolloid components were observed in the values of 160, 1100, and 1870% for different additional hydrocolloid components of carboxymethylcellulose, sodium alginate, and carbomer U10, respectively. New drug-release systems of polyurethane film-backed hydrocolloid/adhesive layers could be designed and established for wound care managements. PMID:25226905

  18. Mointoring Thickness Deviations in Planar Multi-Layered Elastic Structures Using Impedance Signatures

    SciTech Connect

    Fisher, K A

    2007-01-26

    In this letter, a low frequency ultrasonic resonance technique that operates in the (20 - 80 kHz) regime is presented that demonstrates detection of thickness changes on the order of +/- 10{micro}m. This measurement capability is a result of the direct correlation between the electrical impedance of an electro-acoustic transducer and the mechanical loading it experiences when placed in contact with a layered elastic structure. The relative frequency shifts of the resonances peaks can be estimated through a simple one-dimensional transmission model. Separate experimental measurements confirm this technique to be sensitive to subtle changes in the underlying layered elastic structure.

  19. Measurement of thermal noise in multilayer coatings with optimized layer thickness

    SciTech Connect

    Villar, Akira E.; Black, Eric D.; DeSalvo, Riccardo; Libbrecht, Kenneth G.; Michel, Christophe; Morgado, Nazario; Pinard, Laurent; Pinto, Innocenzo M.; Pierro, Vincenzo; Galdi, Vincenzo; Principe, Maria; Taurasi, Ilaria

    2010-06-15

    A standard quarter-wavelength multilayer optical coating will produce the highest reflectivity for a given number of coating layers, but in general it will not yield the lowest thermal noise for a prescribed reflectivity. Coatings with the layer thicknesses optimized to minimize thermal noise could be useful in future generation interferometric gravitational wave detectors where coating thermal noise is expected to limit the sensitivity of the instrument. We present the results of direct measurements of the thermal noise of a standard quarter-wavelength coating and a low noise optimized coating. The measurements indicate a reduction in thermal noise in line with modeling predictions.

  20. Correlation of Retinal Nerve Fiber Layer Thickness and Visual Fields in Glaucoma: A broken stick model

    PubMed Central

    Alasil, Tarek; Wang, Kaidi; Yu, Fei; Field, Matthew G.; Lee, Hang; Baniasadi, Neda; de Boer, Johannes F.; Coleman, Anne L.; Chen, Teresa C.

    2015-01-01

    Purpose To determine the retinal nerve fiber layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss. Design Retrospective cross-sectional study. Methods Eighty seven healthy and 108 glaucoma subjects (one eye per subject) were recruited from an academic institution. All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey visual field analyzer 750i; Carl Zeiss Meditec, Dublin, CA) and spectral domain optical coherence tomography RNFL scans (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Comparison of RNFL thicknesses values with VF threshold values showed a plateau of VF threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values. A broken stick statistical analysis was utilized to estimate the tipping point at which RNFL thickness values are associated with VF defects. The slope for the association between structure and function was computed for data above and below the tipping point. Results The mean RNFL thickness value that was associated with initial VF loss was 89 μm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 μm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73 μm. The differences between all the slopes above and below the aforementioned tipping points were statistically significant (p<0.001). Conclusions In open angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable. PMID:24487047

  1. Thickness effects on the Coulomb drag rate in double quantum layer systems

    NASA Astrophysics Data System (ADS)

    Vazifehshenas, T.; Eskourchi, A.

    2007-02-01

    In this paper, we have investigated the effect of quantum layer thickness on Coulomb drag phenomenon in a double quantum well (DQW) system, in which the electrons momentum can transfer from one layer to another. We have applied the full random phase approximation (RPA) in dynamical dielectric matrix of this coupled two-dimensional electron gas (2DEG) system in order to obtain an improved result for temperature-dependent rate of momentum transfer. We have calculated the drag rate transresistivity for various well thicknesses at low and intermediate temperatures in Fermi-scale and for different electron gas densities. It has been obtained that the Coulomb drag rate increases with increasing the well width when the separation between the wells remains unchanged.

  2. Imperfect hybrid layers created by an aggressive one-step self-etch adhesive in primary dentin are amendable to biomimetic remineralization in vitro

    PubMed Central

    Kim, Jongryul; Vaughn, Ryan M.; Gu, Lisha; Rockman, Roy A.; Arola, Dwayne D.; Schafer, Tara E.; Choi, Kyungkyu; Pashley, David H.; Tay, Franklin R.

    2009-01-01

    Degradation of hybrid layers created in primary dentin occurs as early as 6 months in vivo. Biomimetic remineralization utilizes “bottom-up” nanotechnology principles for interfibrillar and intrafibrillar remineralization of collagen matrices. This study examined whether imperfect hybrid layers created in primary dentin can be remineralized. Coronal dentin surfaces were prepared from extracted primary molars and bonded using Adper Prompt L-Pop and a composite. One millimeter-thick specimen slabs of the resin-dentin interface were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs to mimic the sequestration and templating functions of dentin noncollagenous proteins. Specimens were retrieved after 1–6 months. Confocal laser scanning microscopy was employed for evaluating the permeability of hybrid layers to Rhodamine B. Transmission electron microscopy was used to examine the status of remineralization within hybrid layers. Remineralization at different locations of the hybrid layers corresponded with quenching of fluorescence within similar locations of those hybrid layers. Remineralization was predominantly intrafibrillar in nature as interfibrillar spaces were filled with adhesive resin. Biomimetic remineralization of imperfect hybrid layers in primary human dentin is a potential means for preserving bond integrity. The success of the current proof-of-concept, laterally-diffusing remineralization protocol warrants development of a clinically-applicable biomimetic remineralization delivery system. PMID:19768792

  3. Theoretical Determination of The Optimum Thickness of Perylene Layer in Bilayer Phthalocyanine/Perylene Photovoltaic Device

    NASA Astrophysics Data System (ADS)

    Pratiwi, Herlina; Siahaan, Timothy; Satriawan, Mirza; Nurwantoro, Pekik; Triyana, Kuwat

    2009-09-01

    We do theoretical study on thickness of the active layers in a heterojunction bilayer thin film photovoltaic device based on copper phthalocyanine (CuPc)/perylene that gives the highest Incident Photon to Current Efficiency (IPCE). The device we study consists Glass (1 mm)/ITO (Indium Tin Oxide, 120 nm)/CuPc (50 nm)/PTCDA (3, 4, 9, 10-perylenetetracarboxylic dianhydride, x nm)/Ag (40 nm), where x is the thickness of the PTCDA layer that we calculate here. The calculation is based on assumption that the photocurrent generation process is the result of the creation of photogenerated excitons, which difuse before dissociated at the CuPc/PTCDA interface following the diffusion equation, by internal optical electric field that comes from light exposure. We also assume that almost all photocurrent is created in the CuPc/PTCDA interface. Because the order of the thickness of the active layers is the same or smaller than of the wavelength of visible light, we take into account the effect of reflection and interference in the calculation of internal optical electric field distribution inside the device by making use complex indices of refraction of the active materials in our calculation. The modulus of it is proportional with the number generated excitons. The general solution of the exciton diffusion equation was used for calculating the photocurrent and the IPCE. Here, we find the optimum thickness of PTCDA layer that gives greatest IPCE at the wavelength of 344 nm and 467 nm, which are the wavelengths at which the absorption coefficients of CuPc and PTCDA, respectively, reach the maximum values.

  4. Macular Microcysts in Mitochondrial Optic Neuropathies: Prevalence and Retinal Layer Thickness Measurements

    PubMed Central

    Carbonelli, Michele; La Morgia, Chiara; Savini, Giacomo; Cascavilla, Maria Lucia; Borrelli, Enrico; Chicani, Filipe; do V. F. Ramos, Carolina; Salomao, Solange R.; Parisi, Vincenzo; Sebag, Jerry; Bandello, Francesco; Sadun, Alfredo A.; Carelli, Valerio; Barboni, Piero

    2015-01-01

    Purpose To investigate the thickness of the retinal layers and to assess the prevalence of macular microcysts (MM) in the inner nuclear layer (INL) of patients with mitochondrial optic neuropathies (MON). Methods All patients with molecularly confirmed MON, i.e. Leber’s Hereditary Optic Neuropathy (LHON) and Dominant Optic Atrophy (DOA), referred between 2010 and 2012 were enrolled. Eight patients with MM were compared with two control groups: MON patients without MM matched by age, peripapillary retinal nerve fiber layer (RNFL) thickness, and visual acuity, as well as age-matched controls. Retinal segmentation was performed using specific Optical coherence tomography (OCT) software (Carl Zeiss Meditec). Macular segmentation thickness values of the three groups were compared by one-way analysis of variance with Bonferroni post hoc corrections. Results MM were identified in 5/90 (5.6%) patients with LHON and 3/58 (5.2%) with DOA. The INL was thicker in patients with MON compared to controls regardless of the presence of MM [133.1±7μm vs 122.3±9μm in MM patients (p<0.01) and 128.5±8μm vs. 122.3±9μm in no-MM patients (p<0.05)], however the outer nuclear layer (ONL) was thicker in patients with MM (101.4±1mμ) compared to patients without MM [77.5±8mμ (p<0.001)] and controls [78.4±7mμ (p<0.001)]. ONL thickness did not significantly differ between patients without MM and controls. Conclusion The prevalence of MM in MON is low (5-6%), but associated with ONL thickening. We speculate that in MON patients with MM, vitreo-retinal traction contributes to the thickening of ONL as well as to the production of cystic spaces. PMID:26047507

  5. Oscillating layer thickness and vortices generated in oscillation of finite plate

    NASA Astrophysics Data System (ADS)

    Sin, V. K.; Wong, I. K.

    2016-06-01

    Moving mesh strategy is used in the model of flow induced by oscillating finite plate through software - COMSOL Multiphysics. Flow is assumed to be laminar and arbitrary Lagrangian-Eulerian method is used for moving mesh in the simulation. Oscillating layer thickness is found which is different from the analytical solution by 2 to 3 times depends on the oscillating frequency. Vortices are also observed near the oscillating finite plate because of the edge effect of the finite plate.

  6. Multi-pulse LIBDE of fused silica at different thicknesses of the organic absorber layer

    NASA Astrophysics Data System (ADS)

    Pan, Yunxiang; Ehrhardt, Martin; Lorenz, Pierre; Han, Bing; Hopp, Bela; Vass, Csaba; Ni, Xiaowu; Zimmer, Klaus

    2015-12-01

    Laser-induced etching techniques feature several unique characteristics that enable ultraprecise machining of transparent materials. However, LIBDE (laser-induced back side dry etching) and LIBWE (laser-induced back side wet etching) are preferentially studied due to experimental feasibilities either using a very thin or a bulk absorber at the rear side of the transparent material. This study aims to fill the gap by examining the thickness dependence of the absorbing material. Multi-pulse-LIBDE (MP-LIBDE) of fused silica using different thick photoresist absorber layers (dL = 0.2-11.7 μm) was performed with a KrF excimer laser (λ = 248 nm, tp ≈ 20 ns). The influence of several experimental parameters, such as laser fluence, pulse number, film thickness, on the ablation morphology and the etching rate were investigated. Especially at moderate fluences (F = 0.7-1.5 J/cm2) MP-LIBDE and LIBWE show several similar process characteristics such as the etching rate dependence on the laser fluence and the pulse number with a typical etching rate of approx. 12 nm at 1 J/cm2. However, the specific etching rate values depend on the absorber layer thickness, for instance. The morphology of the etched surface is smooth with a roughness of below 5 nm rms. Further, the modification of the surface has been observed and will be discussed in relation to the multi-pulse laser etching mechanism.

  7. Effects of the Thickness of Niobium Surface Oxide Layers on Field Emission

    SciTech Connect

    A.T. Wu, S. Jin, J.D. Mammosser, R.A. Rimmer, X.Y. Lu, K. Zhao

    2011-09-01

    Field emission on the inner surfaces of niobium superconducting radio frequency cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results* seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3 nm up to 460 nm. A home-made scanning field emission microscope was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The SFEM experimental results were analyzed in terms of surface morphology and oxide thickness of Nb samples and chemical composition and geographic shape of the emitters. A model based on the classic electromagnetic theory was developed trying to understand the experimental results. Possibly implications for Nb SRF cavity applications from this study will be discussed.

  8. Melanoma thickness measurement in two-layer tissue phantoms using pulsed photothermal radiometry (PPTR)

    NASA Astrophysics Data System (ADS)

    Wang, Tianyi; Qiu, Jinze; Paranjape, Amit; Milner, Thomas E.

    2009-02-01

    Melanoma is a malignant tumor of melanocytes which are found predominantly in skin. Melanoma is one of the rarer types of skin cancer but causes the majority of skin cancer related deaths. The staging of malignant melanoma using Breslow thickness is important because of the relationship to survival rate after five years. Pulsed photothermal radiometry (PPTR) is based on the time-resolved acquisition of infrared (IR) emission from a sample after pulsed laser exposure. PPTR can be used to investigate the relationship between melanoma thickness and detected radiometric temperature using two-layer tissue phantoms. We used a Monte Carlo simulation to mimic light transport in melanoma and employed a three-dimensional heat transfer model to obtain simulated radiometric temperature increase and, in comparison, we also conducted PPTR experiments to confirm our simulation results. Simulation and experimental results show similar trends: thicker absorbing layers corresponding to deeper lesions produce slower radiometric temperature decays. A quantitative relationship exists between PPTR radiometric temperature decay time and thickness of the absorbing layer in tissue phantoms.

  9. Macular Ganglion Cell Inner Plexiform Layer Thickness in Glaucomatous Eyes with Localized Retinal Nerve Fiber Layer Defects

    PubMed Central

    Zhang, Chunwei; Tatham, Andrew J.; Abe, Ricardo Y.; Hammel, Na’ama; Belghith, Akram; Weinreb, Robert N.; Medeiros, Felipe A.; Liebmann, Jeffrey M.; Girkin, Christopher A.; Zangwill, Linda M.

    2016-01-01

    Purpose To investigate macular ganglion cell–inner plexiform layer (mGCIPL) thickness in glaucomatous eyes with visible localized retinal nerve fiber layer (RNFL) defects on stereophotographs. Methods 112 healthy and 149 glaucomatous eyes from the Diagnostic Innovations in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES) subjects had standard automated perimetry (SAP), optical coherence tomography (OCT) imaging of the macula and optic nerve head, and stereoscopic optic disc photography. Masked observers identified localized RNFL defects by grading of stereophotographs. Result 47 eyes had visible localized RNFL defects on stereophotographs. Eyes with visible localized RNFL defects had significantly thinner mGCIPL thickness compared to healthy eyes (68.3 ± 11.4 μm versus 79.2 ± 6.6 μm respectively, P<0.001) and similar mGCIPL thickness to glaucomatous eyes without localized RNFL defects (68.6 ± 11.2 μm, P = 1.000). The average mGCIPL thickness in eyes with RNFL defects was 14% less than similarly aged healthy controls. For 29 eyes with a visible RNFL defect in just one hemiretina (superior or inferior) mGCIPL was thinnest in the same hemiretina in 26 eyes (90%). Eyes with inferior-temporal RNFL defects also had significantly thinner inferior-temporal mGCIPL (P<0.001) and inferior mGCIPL (P = 0.030) compared to glaucomatous eyes without a visible RNFL defect. Conclusion The current study indicates that presence of a localized RNFL defect is likely to indicate significant macular damage, particularly in the region of the macular that topographically corresponds to the location of the RNFL defect. PMID:27537107

  10. Predicting the Equilibrium Deuterium-Tritium Fuel Layer Thickness Profile in an Indirect-Drive Hohlraum Capsule

    SciTech Connect

    Sanchez, Jorge J.; Giedt, Warren H.

    2004-03-15

    A numerical procedure for calculating the equilibrium thickness distribution of a thin layer of deuterium and tritium on the inner surface of an indirect drive target sphere ({approx}2.0 mm in diameter) is described. Starting with an assumed uniform thickness layer and with specified thermal boundary conditions, the temperature distribution throughout the capsule and hohlraum (including natural convection in the hohlraum gas) is calculated. Results are used to make a first estimate of the final non-uniform thickness distribution of the layer. This thickness distribution is then used to make a second calculation of the temperature distribution with the same boundary conditions. Legendre polynomial coefficients are evaluated for the two temperature distributions and the two thickness profiles. Final equilibrium Legendre coefficients are determined by linear extrapolation. From these coefficients, the equilibrium layer thickness can be computed.

  11. Predicting the Equilibrium Deuterium-Tritium Fuel Layer Thickness Profile in an Indirect-Drive Hohlraum Capsule

    SciTech Connect

    Sanchez, J J; Giedt, W H

    2003-09-02

    A numerical procedure for calculating the equilibrium thickness distribution of a thin layer of deuterium and tritium on the inner surface of an indirect drive target sphere ({approx} 2.0 mm in diameter) is described. Starting with an assumed uniform thickness layer and with specified thermal boundary conditions, the temperature distribution throughout the capsule and hohlraum (including natural convection in the hohlraum gas) is calculated. Results are used to make a first estimate of the final non-uniform thickness distribution of the layer. This thickness distribution is then used to make a second calculation of the temperature distribution with the same boundary conditions. Legendre polynomial coefficients are evaluated for the two temperature distributions and the two thickness profiles. Final equilibrium Legendre coefficients are determined by linear extrapolation. From these coefficients, the equilibrium layer thickness can be computed.

  12. Ultrasonographic evaluation of relative gastrointestinal layer thickness in cats without clinical evidence of gastrointestinal tract disease.

    PubMed

    Winter, Matthew D; Londono, Leonel; Berry, Clifford R; Hernandez, Jorge A

    2014-02-01

    The objectives of this study were (1) to measure normal thickness values of the muscularis, submucosal, mucosal and serosal layers in each gastrointestinal (GI) segment (gastric fundus, body and pyloric antrum; duodenum; jejunum; ileum; colon), and (2) to calculate a ratio of muscularis and mucosal layer thickness to aortic diameter measured at the level of the celiac artery (Musc:Ao and Muc:Ao) in each GI segment in a sample of healthy cats. Ultrasonographic examination of the GI tract was performed, and measurements of the individual layers in each GI segment were obtained in 38 healthy cats without clinical evidence of disease. The muscularis layer was significantly thickest in the ileum, compared with other segments, and it was thicker than the submucosa in all segments except the colon. The mucosa was the thickest layer in all segments, and was thickest in the duodenum and ileum. Measurements of the submucosal and serosal layers were not significantly different between all segments. Musc:Ao and Muc:Ao in each segment were 0.12 and 0.25 (gastric fundus), 0.12 and 0.18 (gastric body), 0.11 and 0.16 (pyloric antrum), 0.08 and 0.27 (duodenum), 0.08 and 0.22 (jejunum), 0.14 and 0.25 (ileum), and 0.05 and 0.08 (colon), respectively. Musc:Ao and Muc:Ao are clinically relevant values that can be used to objectively identify thickening of the muscularis and mucosal layers in response to GI diseases. PMID:23906704

  13. To determine ice layer thickness of Europa by high energy neutrino

    NASA Astrophysics Data System (ADS)

    Shoji, D.; Kurita, K.; Tanaka, H. K.

    2010-12-01

    Europa, the second closest Galilean satellite is one of the targets which are suspected to have an internal ocean. Detection and characterization of the internal ocean is one of the main subjects for Europa orbiter exploration. Although the gravitational data has shown the thickness of the surface H2O layer of 80-170km[1], it can not determine the phase of H2O. The variations in the magnetic field associated with the induced current in the internal ocean can determine the thickness of the layer of ice if satellite's orbits satisfy the required conditions. Observations of tidal amplitude forced by Jupiter can also resolve the thickness of the surface lithosphere[2]. At moment because of the lack of observational constraints there exist two contrasting models:thick ice layer model and thin model. Here we propose new method to detect the ocean directly based on the radiation by high energy neutrino interacted with matter. Schaefer et al[3] have proposed a similar method to determine ice layer thickness. We will focus on the detection of internal ocean for Europa and present the method is suitable for actual situations of Europa exploration by numerical simulations. Neutrino is famous for its traveling at long distance without any interaction with matter. When high energy neutrinos traverse in Europa hadronic showers are produced by the weak interaction with the nucleons that makes the body of Europa. These hadronic showers induces excess electrons. Because of these excess electrons, Cherenkov photons are emitted. When this radiation occurs in the ice layer, radiations whose wave length is over 10cm should be coherent because the scale of the shower becomes small (a few cm) in the ice, which is called as Askaryan effect[3]. Thus, the intensity of the radiation whose frequency is a few GHz should be enhanced. Since ice has a much longer attenuation length than water, the radiations which occur in the surface ice layer could be detected by the antenna outside Europa but

  14. Determination of the thickness and orientation of few-layer tungsten ditelluride using polarized Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Minjung; Han, Songhee; Kim, Jung Hwa; Lee, Jae-Ung; Lee, Zonghoon; Cheong, Hyeonsik

    2016-09-01

    Orthorhombic tungsten ditelluride (WTe2), with a distorted 1T structure, exhibits a large magnetoresistance that depends on the orientation, and its electrical characteristics changes from semimetallic to insulating as the thickness decreases. Through polarized Raman spectroscopy in combination with transmission electron diffraction, we establish a reliable method to determine the thickness and crystallographic orientation of few-layer WTe2. The Raman spectrum shows a pronounced dependence on the polarization of the excitation laser. We found that the separation between two Raman peaks at ∼90 cm‑1 and at 80–86 cm‑1, depending on thickness, is a reliable fingerprint for determination of the thickness. For determination of the crystallographic orientation, the polarization dependence of the A 1 modes, measured with the 632.8 nm excitation, turns out to be the most reliable. We also discovered that the polarization behaviors of some of the Raman peaks depend on the excitation wavelength as well as thickness, indicating a close interplay between the band structure and anisotropic Raman scattering cross section.

  15. On-Line Thickness Measurement for Two-Layer Systems on Polymer Electronic Devices

    PubMed Central

    Grassi, Ana Perez; Tremmel, Anton J.; Koch, Alexander W.; El-Khozondar, Hala J.

    2013-01-01

    During the manufacturing of printed electronic circuits, different layers of coatings are applied successively on a substrate. The correct thickness of such layers is essential for guaranteeing the electronic behavior of the final product and must therefore be controlled thoroughly. This paper presents a model for measuring two-layer systems through thin film reflectometry (TFR). The model considers irregular interfaces and distortions introduced by the setup and the vertical vibration movements caused by the production process. The results show that the introduction of these latter variables is indispensable to obtain correct thickness values. The proposed approach is applied to a typical configuration of polymer electronics on transparent and non-transparent substrates. We compare our results to those obtained using a profilometer. The high degree of agreement between both measurements validates the model and suggests that the proposed measurement method can be used in industrial applications requiring fast and non-contact inspection of two-layer systems. Moreover, this approach can be used for other kinds of materials with known optical parameters. PMID:24253192

  16. Shear horizontal acoustic waves propagating along two isotropic solid plates bonded with a non-dissipative adhesive layer: Effects of the rough interfaces

    NASA Astrophysics Data System (ADS)

    Potel, Catherine; Bruneau, Michel; Foze N'Djomo, Ludovic C.; Leduc, Damien; Echcherif Elkettani, Mounsif; Izbicki, Jean-Louis

    2015-12-01

    The aim of this paper is to provide an analytical contribution which presents the application of shear-horizontal (SH)-guided waves for the characterisation of a bi-layered structure which consists of two isotropic plates adhesively bonded using a non-dissipative thin layer of glue. The thickness of the layer of glue is assumed to be non-negligible, and the interfaces between this layer of glue and the plates are both assumed to be roughened (parallel ridges with complex shape and depth profiles). The basis of the theoretical approach is an extension of the integral formulation, in the frame of SH modal couplings due to the roughness, which has been developed previously for SH-wave propagation over a single plate with a rough surface. This approach assumes that the average roughness height is a small fraction of the thicknesses of the waveguides (the plates) everywhere. The changes, due to the roughness, in the characteristics of the fields created by a harmonic source set at the entrance edge of the structure are expressed through the mapping of the displacement and stress perturbations. Preliminary tests of the effectiveness of the model are given; they rely on the phase-matching effects of periodic profiles and pseudo-random experimental profile.

  17. Lithospheric strength and its relationship to the elastic and seismogenic layer thickness

    NASA Astrophysics Data System (ADS)

    Watts, A. B.; Burov, E. B.

    2003-08-01

    Plate flexure is a phenomenon that describes how the lithosphere responds to long-term (>105 yr) geological loads. By comparing the flexure in the vicinity of ice, volcano, and sediment loads to predictions based on simple plate models it has been possible to estimate the effective elastic thickness of the lithosphere, Te. In the oceans, Te is the range 2-50 km and is determined mainly by plate and load age. The continents, in contrast, are characterised by Te values of up to 80 km and greater. Rheological considerations based on data from experimental rock mechanics suggest that Te reflects the integrated brittle, elastic and ductile strength of the lithosphere. Te differs, therefore, from the seismogenic layer thickness, Ts, which is indicative of the depth to which anelastic deformation occurs as unstable frictional sliding. Despite differences in their time scales, Te and Ts are similar in the oceans where loading reduces the initial mechanical thickness to values that generally coincide with the thickness of the brittle layer. They differ, however, in continents, which, unlike oceans, are characterised by a multi-layer rheology. As a result, Te≫Ts in cratons, many convergent zones, and some rifts. Most rifts, however, are characterised by a low Te that has been variously attributed to a young thermal age of the rifted lithosphere, thinning and heating at the time of rifting, and yielding due to post-rift sediment loading. Irrespective of their origin, the Wilson cycle makes it possible for low values to be inherited by foreland basins which, in turn, helps explain why similarities between Te and Ts extend beyond rifts into other tectonic regions such as orogenic belts and, occasionally, the cratons themselves.

  18. Thickness-dependent Dielectric Constant of Few-layer In2Se3 Nano-flakes

    NASA Astrophysics Data System (ADS)

    Wu, Di; Pak, Alexander; Liu, Yingnan; Wu, Xiaoyu; Ren, Yuan; Tsai, Yu-Hao; Lin, Min; Peng, Hailin; Hwang, Gyeong; Lai, Keji

    2015-03-01

    The dielectric constant or relative permittivity of active materials in electronic devices is a critical parameter for charging and screening effects. For layered two-dimensional (2D) materials, it is of great interest to understand how their dielectric constants depend on dimensionalities and the arrangement of crystal lattices. Here we present both experimental and theoretical investigations on the dielectric constant of few-layer In2Se3 nano-flakes grown on mica substrates by van der Waals epitaxy. A nondestructive microwave impedance microscope (MIM) is employed to simultaneously quantify the number of layers and local electrical and optical properties. The measured effective dielectric constant increases monotonically as a function of the thickness and saturates to the bulk value at around 6-8 quintuple layers. The same trend of layer-dependent dielectric constant is also revealed through a density functional theory approach. Our results of the dielectric response are expected to be significant for the applications of layered materials in nano-devices.

  19. Impact of silicon epitaxial thickness layer in high power diode devices

    NASA Astrophysics Data System (ADS)

    Mee, Cheh Chai; Arshad, M. K. Md.; Hashim, U.; Fathil, M. F. M.

    2016-07-01

    The p-i-n diode is one of the earliest semiconductor devices developed for power circuit application. It is formed with the intrinsically doped i.e. i-layer sandwiched between the p-type and n-type layers. In this paper, we focus on the integration of the intrinsic region of silicon p-i-n diode to the current-voltage characteristics. In our structure, n-type refers to the bulk substrate and intrinsic region refers to the epitaxial layer of the silicon substrate. We make a thickness variation in the intrinsic region of p-i-n diode and how it affects diode performance. An additional layer is added on the epitaxial layer during the process to control the diffusion from the bottom of bulk substrate. Result shows that intrinsic layer optimization has successfully enhances the diode device robustness in terms of diode current-voltage characteristics, which reflects better manufacturing yield and improve the final product performance.

  20. Attenuation Tomography of Body Waves in Thickness-varying Layered Media

    NASA Astrophysics Data System (ADS)

    Cao, H.; Zhou, H.

    2006-12-01

    The intrinsic attenuation of seismic waves, which is quantified as inverse to the quality factor (Q) of a medium, is a well-publicized and yet poorly studied subject. While it is common to deduce Q values from measured dispersion data for surface waves, previous studies on the intrinsic attenuation of body waves have relied on measurements of the waveform of first arrivals or reflections. Better understanding is needed for both solid Earth geophysics and applied seismology to quantify the contributing factors to seismic attenuation and decompose Q from other factors because Q is closely related to rock property and fluid saturation. This study focuses on forward modeling and tomographic inversion for the Q values in thickness-varying layered media. Many of the existing theoretical Q models work in such media. Our work is an extension of the deformable- layer tomography (Zhou, 2004) to dissipative media. In the first phase of this study, we evaluated, through numerical modeling the various factors contributing to the attenuation of body waves. Theoretically, there are intrinsic attenuation, which is related to rock and pore fluid properties, and attenuation due to wave propagation effects, such as geometrical spreading and energy partition across interfaces (transmission and reflection). We made several representative numerical models, and conducted forward modeling using both wave theory and ray theory to quantify the amount of the attenuation of body waves due to different factors. In the second phase, we are integrating the forward modeling with the deformable-layer tomography algorithm to develop means to invert for Q distribution in thickness-varying layer media. While the deformable-layer tomography determines layer velocities and geometry, the current work intends to invert for Q values of the thickness-varying model layers as well as parameters associated with interface energy partition and geometric spreading. In the third phase, we plan to apply the

  1. Optical quantification of epithelial layer thickness as a measure of oral inflammation

    NASA Astrophysics Data System (ADS)

    Hattery, David W.; Hattery, Brenda; Hassan, Moinuddin; Chernomordik, Victor V.; Vogel, Abby; Hekmat, Farid; Gandjbakhche, Amir H.

    2003-06-01

    For individuals with cancer risk factors, reducing tissue inflammation may reduce the risk of developing cancer. This is the basis of several clinical trials evaluating potential chemoprevention drugs. These trials require quantitative assessments of inflammation which, for the oral epithelium, are traditionally provided by punch biopsies. To reduce patient discomfort and morbidity, we have developed a non-invasive alternative using diffuse reflectance spectroscopy. Though any optical system has the potential for probing near-surface structures, traditional methods of accounting for scattering of photons are generally invalid for typical epithelial thicknesses. We have previously developed a theory that is valid in this regime and validated it with Monte Carlo simulations. We use a differential measure with acute sensitivity to small changes in layer scattering coefficients. To assess the capability of the approach to quantify epithelial thickness, detailed Monte Carlo simulations and measurements on phantom models of a two layered structure have been performed. Preliminary results from this work show that our key feature varies less than 20 percent despite four-fold changes in scattering coefficients and ten-fold changes in absorption coefficients. This indicates that the method will be of practical clinical value for quantifying epithelial thickness in vivo.

  2. Superconducting layer thickness dependence of magnetic relaxation property in CVD processed YGdBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Kiuchi, M.; Otabe, E. S.; Matsushita, T.; Shikimachi, K.; Watanabe, T.; Kashima, N.; Nagaya, S.

    2011-11-01

    One of the most important properties of coated conductors for Superconducting Magnetic Energy Storage (SMES) is the relaxation property of persistent superconducting current. This property can be quantitatively characterized by the apparent pinning potential U0∗. In this paper, the dependence of U0∗ on the thickness of superconducting layer d is investigated in the range of 0.33-1.43 μm at the temperature range of 20-30 K and in magnetic fields up to 6.5 T for Y 0.7Gd 0.3Ba 2Cu 3O 7- δ coated conductors. It was found that the value of critical current density did not appreciably depend on d at 20 K. This indicates that no structural deterioration of superconducting layer occurs during the process of increasing thickness. U0∗ increases and then tends to decrease with an increasing magnetic field. The magnetic field at which U0∗ starts to decrease increases with increasing thickness. This property was analyzed using the flux creep-flow model. Application of scaling law is examined for the dependence of U0∗ on magnetic field and temperature. It was found that the dependence could be expressed using scaling parameters B,U0 peak∗ in the temperature range 20-30 K.

  3. Quantifying the Distribution and Landscape Controls of Peatlands and Organic Layer Thickness within Alaska

    NASA Astrophysics Data System (ADS)

    Wylie, B. K.; Pastick, N.; Jorgenson, T.; Nield, S.; Johnson, K. D.

    2014-12-01

    The northern circumpolar region is estimated to contain 50 % of the global belowground carbon pool and is experiencing climate change at rates higher than anywhere else globally. Surface organic horizons associated with these immense carbon pools are important to ecosystem functioning in terms of soil moisture and temperature regulations, permafrost degradation, successional trajectories, and soil respiration levels. However, fire-induced changes to surface organics and their distribution are poorly understood, especially on landscape scales. These ambiguities make future predictions uncertain for these significant carbon pools, which have the potential for significant feedbacks to global warming. Moreover, given the significant impacts and increasing severity and amount of fires in boreal systems, the spatial quantification of post-fire surface organic thickness is important for ecosystem model calibrations and comparisons, and can improve future projections of vegetation types and albedo, carbon stocks and fluxes, and future thaw depths. Here we present the results of pioneering studies that quantified the distribution and controls of peatlands and soil organic layer thickness in Alaska through the use of statistical models, field data, spatial analyses, and remote sensing (Landsat). Our empirical modeling approach enabled us to produce medium-resolution (30-m pixels) maps of peatlands and organic layer thickness throughout Alaska, which is important for land management practices and enhances the understanding of the risk and feedbacks associated with fires and climate feedbacks.

  4. Weakly nonlinear Rayleigh-Taylor instability of a finite-thickness fluid layer

    SciTech Connect

    Wang, L. F. Ye, W. H. Liu, Jie; He, X. T.; Guo, H. Y.; Wu, J. F. Zhang, W. Y.

    2014-12-15

    A weakly nonlinear (WN) model has been developed for the Rayleigh-Taylor instability of a finite-thickness incompressible fluid layer (slab). We derive the coupling evolution equations for perturbations on the (upper) “linearly stable” and (lower) “linearly unstable” interfaces of the slab. Expressions of temporal evolutions of the amplitudes of the perturbation first three harmonics on the upper and lower interfaces are obtained. The classical feedthrough (interface coupling) solution obtained by Taylor [Proc. R. Soc. London A 201, 192 (1950)] is readily recovered by the first-order results. Our third-order model can depict the WN perturbation growth and the saturation of linear (exponential) growth of the perturbation fundamental mode on both interfaces. The dependence of the WN perturbation growth and the slab distortion on the normalized layer thickness (kd) is analytically investigated via the third-order solutions. Comparison is made with Jacobs-Catton's formula [J. W. Jacobs and I. Catton, J. Fluid Mech. 187, 329 (1988)] of the position of the “linearly unstable” interface. Using a reduced formula, the saturation amplitude of linear growth of the perturbation fundamental mode is studied. It is found that the finite-thickness effects play a dominant role in the WN evolution of the slab, especially when kd < 1. Thus, it should be included in applications where the interface coupling effects are important, such as inertial confinement fusion implosions and supernova explosions.

  5. Decreased retinal nerve fiber layer thickness in patients with obstructive sleep apnea syndrome

    PubMed Central

    Sun, Cheng-Lin; Zhou, Li-Xiao; Dang, Yalong; Huo, Yin-Ping; Shi, Lei; Chang, Yong-Jie

    2016-01-01

    Abstract Objective: To investigate the changes of retinal nerve fiber layer (RNFL) thickness in obstructive sleep apnea syndrome (OSAS) patients. Methods: Relevant studies were selected from 3 major literature databases (PubMed, Cochrane Library, and EMBASE) without language restriction. Main inclusion criteria is that a case-control study in which RNFL thickness was measured by a commercial available optical coherence tomography (OCT) in OSAS patients. Meta-analysis was performed using STATA 12.0 software. Efficacy estimates were evaluated by weighted mean difference with corresponding 95% confidence intervals (CIs). Primary outcome evaluations were: the average changes of RNFL thickness in total OSAS patients, subgroup analysis of RNFL thickness changes in patients of different OSAS stages, and subgroup analysis of 4-quadrant RNFL thickness changes in total OSAS patients. Results: Of the initial 327 literatures, 8 case-control studies with 763 eyes of OSA patients and 474 eyes of healthy controls were included (NOS scores ≥6). For the people of total OSAS, there had an average 2.92 μm decreased RNFL thickness compared with controls (95% CI: −4.61 to −1.24, P = 0.001). For subgroup analysis of OSAS in different stages, the average changes of RNFL thickness in mild, moderate, severe, and moderate to severe OSAS were 2.05 (95% CI: −4.40 to 0.30, P = 0.088), 2.32 (95% CI: −5.04 to 0.40, P = 0.094), 4.21 (95% CI: −8.36 to −0.06, P = 0.047), and 4.02 (95% CI: −7.65 to −0.40, P = 0.03), respectively. For subgroup analysis of 4-quadrant, the average changes of RNFL thickness in Superior, Nasal, Inferior, and Temporal quadrant were 2.43 (95% CI: −4.28 to −0.57, P = 0.01), 1.41 (95% CI: −3.33 to 0.51, P = 0.151), 3.75 (95% CI: −6.92 to −0.59, P = 0.02), and 0.98 (95% CI: −2.49 to 0.53, P = 0.203), respectively. Conclusion: Our study suggests that RNFL thickness in OSAS patients is much thinner than

  6. The Correlation of Retinal Nerve Fiber Layer Thickness With Blood Pressure in a Chinese Hypertensive Population

    PubMed Central

    Gangwani, Rita A.; Lee, Jacky W.Y.; Mo, H.Y.; Sum, Rita; Kwong, Alfred S.K.; Wang, Jenny H.L.; Tsui, Wendy W.S.; Chan, Jonathan C.H.; Lai, Jimmy S.M.

    2015-01-01

    Abstract To investigate the association between retinal nerve fiber layer (RNFL) thickness and blood pressure (BP) in subjects with systemic hypertension. Subjects with systemic hypertension on anti-hypertensive medications were screened by fundus photography and referred for glaucoma work-up if there was enlarged vertical cup-to-disc (VCDR) ratio ≥0.6, VCDR asymmetry ≥0.2, or optic disc hemorrhage. Workup included a complete ophthalmological examination, Humphrey visual field test, and RNFL thickness measurement by optical coherence tomography. The intraocular pressure (IOP) and RNFL thicknesses (global and quadrant) were averaged from both eyes and the means were correlated with: the systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) using Pearson correlation. Among 4000 screened hypertensive subjects, 133 were referred for glaucoma workup and 110 completed the workup. Of the 4000 screened subjects, 1.3% had glaucoma (0.9% had normal tension glaucoma [NTG], 0.2% had primary open angle glaucoma, and 0.2% had primary angle closure glaucoma), whereas 0.3% were NTG suspects. The SBP was negatively correlated with the mean superior RNFL thickness (P = 0.01). The DBP was negatively correlated with the mean global (P = 0.03), superior (P = 0.02), and nasal (P = 0.003) RNFL thickness. The MAP was negatively correlated with the mean global (P = 0.01), superior (P = 0.002), and nasal (P = 0.004) RNFL thickness while positively correlated with the mean IOP (P = 0.02). In medically treated hypertensive subjects, glaucoma was present in 1.3%, with NTG being most prevalent. MAP control may help with IOP lowering and RNFL preservation, although future prospective studies will be needed. PMID:26061324

  7. Electrocaloric properties of ferroelectric-paraelectric superlattices controlled by the thickness of paraelectric layer in a wide temperature range

    SciTech Connect

    Ma, D. C.; Lin, S. P.; Chen, W. J.; Zheng, Yue Xiong, W. M.; Wang, Biao

    2014-10-15

    As functions of the paraelectric layer thickness, misfit strain and temperature, the electrocaloric properties of ferroelectric-paraelectric superlattices are investigated using a time-dependent Ginzburg-Landau thermodynamic model. Ferroelectric phase transition driven by the relative thickness of the superlattice is found to dramatically impact the electrocaloric response. Near the phase transition temperature, the magnitude of the electrocaloric effect is maximized and shifted to lower temperatures by increasing the relative thickness of paraelectric layer. Theoretical calculations also imply that the electrocaloric effect of the superlattices depends not only on the relative thickness of paraelectric layer but also on misfit strain. Furthermore, control of the relative thickness of paraelectric layer and the misfit strain can change availably both the magnitude and the temperature sensitivity of the electrocaloric effect, which suggests that ferroelectric-paraelectric superlattices may be promising candidates for use in cooling devices in a wide temperature range.

  8. Thickness-dependent electron mobility of single and few-layer MoS2 thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Ji Heon; Kim, Tae Ho; Lee, Hyunjea; Park, Young Ran; Choi, Woong; Lee, Cheol Jin

    2016-06-01

    We investigated the dependence of electron mobility on the thickness of MoS2 nanosheets by fabricating bottom-gate single and few-layer MoS2 thin-film transistors with SiO2 gate dielectrics and Au electrodes. All the fabricated MoS2 transistors showed on/off-current ratio of ˜107 and saturated output characteristics without high-k capping layers. As the MoS2 thickness increased from 1 to 6 layers, the field-effect mobility of the fabricated MoS2 transistors increased from ˜10 to ˜18 cm2V-1s-1. The increased subthreshold swing of the fabricated transistors with MoS2 thickness suggests that the increase of MoS2 mobility with thickness may be related to the dependence of the contact resistance and the dielectric constant of MoS2 layer on its thickness.

  9. Is Retinal Nerve Fiber Layer Thickness Change Related to Headache Lateralization in Migraine?

    PubMed Central

    Demirci, Seden; Tok, Levent; Tok, Ozlem; Demirci, Serpil; Kutluhan, Süleyman

    2016-01-01

    Purpose To evaluate retinal nerve fiber layer (RNFL) thickness in migraine patients with unilateral headache. Methods A total of 58 patients diagnosed with migraine headache consistently occurring on the same side and 58 age- and sex-matched healthy subjects were evaluated in this cross-sectional study. RNFL thickness was measured using spectral-domain optical coherence tomography, and the side with the headache was com-pared with the contralateral side as well as with the results of healthy subjects. Results The mean patient age was 33.05 ± 8.83 years, and that of the healthy subjects was 31.44 ± 8.64 years (p = 0.32). The mean duration of disease was 10.29 ± 9.03 years. The average and nasal RNFL thicknesses were significantly thinner on the side of headache and on the contralateral side compared to control eyes (p < 0.05, for all). Thinning was higher on the side of the headache compared to the contralateral side; however, this difference was not statistically significant. Conclusions The RNFL thicknesses were thinner on the side of the headache compared to the contralateral side in the migraine patients with unilateral headache, but this difference was not statistically significant. PMID:27051262

  10. A metal-oxide-semiconductor radiation dosimeter with a thick and defect-rich oxide layer

    NASA Astrophysics Data System (ADS)

    Liu, Hongrui; Yang, Yuhao; Zhang, Jinwen

    2016-04-01

    Enhancing the density of defects in the oxide layer is the main factor in improving the sensitivity of a metal-oxide-semiconductor (MOS) radiation dosimeter. This paper reports a novel MOS dosimeter with a very thick and defect-rich oxide layer fabricated by MEMS technology. The category of defects in SiO2 and their possible effect on the radiation dose sensing was analyzed. Then, we proposed combining deep-reactive-ion etching, thermal oxidation and low pressure chemical vapor deposition to realize an oxide layer containing multiple and large interfaces which can increase defects significantly. The trench-and-beam structure of silicon was considered in detail. The fabrication process was developed for obtaining a thick and compact MEMS-made SiO2. Our devices were irradiated by γ-rays of 60Co at 2 Gy per minute for 2 h and a thermally stimulated current (TSC) method was used to determine the readout of the dosimeters. Results show that there is a peak current of about 450 nA, indicating a total TSC charge of 158 μC and sensitivity of 1.1 μC mm-3·Gy, which is 40 times the sensitivity of previous MOS dosimeters.

  11. Thickness-Dependent Dielectric Constant of Few-Layer In₂Se₃ Nanoflakes.

    PubMed

    Wu, Di; Pak, Alexander J; Liu, Yingnan; Zhou, Yu; Wu, Xiaoyu; Zhu, Yihan; Lin, Min; Han, Yu; Ren, Yuan; Peng, Hailin; Tsai, Yu-Hao; Hwang, Gyeong S; Lai, Keji

    2015-12-01

    The dielectric constant or relative permittivity (ε(r)) of a dielectric material, which describes how the net electric field in the medium is reduced with respect to the external field, is a parameter of critical importance for charging and screening in electronic devices. Such a fundamental material property is intimately related to not only the polarizability of individual atoms but also the specific atomic arrangement in the crystal lattice. In this Letter, we present both experimental and theoretical investigations on the dielectric constant of few-layer In2Se3 nanoflakes grown on mica substrates by van der Waals epitaxy. A nondestructive microwave impedance microscope is employed to simultaneously quantify the number of layers and local electrical properties. The measured ε(r) increases monotonically as a function of the thickness and saturates to the bulk value at around 6-8 quintuple layers. The same trend of layer-dependent dielectric constant is also revealed by first-principles calculations. Our results of the dielectric response, being ubiquitously applicable to layered 2D semiconductors, are expected to be significant for this vibrant research field. PMID:26575786

  12. The impact of layer thickness on the performance of additively manufactured lapping tools

    NASA Astrophysics Data System (ADS)

    Williams, Wesley B.

    2015-10-01

    Lower cost additive manufacturing (AM) machines which have emerged in recent years are capable of producing tools, jigs, and fixtures that are useful in optical fabrication. In particular, AM tooling has been shown to be useful in lapping glass workpieces. Various AM machines are distinguished by the processes, materials, build times, and build resolution they provide. This research investigates the impact of varied build resolution (specifically layer resolution) on the lapping performance of tools built using the stereolithographic assembly (SLA) process in 50 μm and 100 μm layer thicknesses with a methacrylate photopolymer resin on a high resolution desktop printer. As with previous work, the lapping tools were shown to remove workpiece material during the lapping process, but the tools themselves also experienced significant wear on the order of 2-3 times the mass loss of the glass workpieces. The tool wear rates for the 100 μm and 50 μm layer tools were comparable, but the 50 μm layer tool was 74% more effective at removing material from the glass workpiece, which is attributed to some abrasive particles being trapped in the coarser surface of the 100 um layer tooling and not being available to interact with the glass workpiece. Considering the tool wear, these additively manufactured tools are most appropriate for prototype tooling where the low cost (<$45) and quick turnaround make them attractive when compared to a machined tool.

  13. Atmospheric pressure spatial atomic layer deposition web coating with in situ monitoring of film thickness

    SciTech Connect

    Yersak, Alexander S.; Lee, Yung C.; Spencer, Joseph A.; Groner, Markus D.

    2014-01-15

    Spectral reflectometry was implemented as a method for in situ thickness monitoring in a spatial atomic layer deposition (ALD) system. Al{sub 2}O{sub 3} films were grown on a moving polymer web substrate at 100 °C using an atmospheric pressure ALD web coating system, with film growth of 0.11–0.13 nm/cycle. The modular coating head design and the in situ monitoring allowed for the characterization and optimization of the trimethylaluminum and water precursor exposures, purge flows, and web speed. A thickness uniformity of ±2% was achieved across the web. ALD cycle times as low as 76 ms were demonstrated with a web speed of 1 m/s and a vertical gap height of 0.5 mm. This atmospheric pressure ALD system with in situ process control demonstrates the feasibility of low-cost, high throughput roll-to-roll ALD.

  14. Influences and interactions of inundation, peat, and snow on active layer thickness: Modeling Archive

    DOE Data Explorer

    Scott Painter; Ethan Coon; Cathy Wilson; Dylan Harp; Adam Atchley

    2016-04-21

    This Modeling Archive is in support of an NGEE Arctic publication currently in review [4/2016]. The Advanced Terrestrial Simulator (ATS) was used to simulate thermal hydrological conditions across varied environmental conditions for an ensemble of 1D models of Arctic permafrost. The thickness of organic soil is varied from 2 to 40cm, snow depth is varied from approximately 0 to 1.2 meters, water table depth was varied from -51cm below the soil surface to 31 cm above the soil surface. A total of 15,960 ensemble members are included. Data produced includes the third and fourth simulation year: active layer thickness, time of deepest thaw depth, temperature of the unfrozen soil, and unfrozen liquid saturation, for each ensemble member. Input files used to run the ensemble are also included.

  15. Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology

    NASA Astrophysics Data System (ADS)

    Krimi, Soufiene; Klier, Jens; Jonuscheit, Joachim; von Freymann, Georg; Urbansky, Ralph; Beigang, René

    2016-07-01

    In this contribution, we present a highly accurate approach for thickness measurements of multi-layered automotive paints using terahertz time domain spectroscopy in reflection geometry. The proposed method combines the benefits of a model-based material parameters extraction method to calibrate the paint coatings, a generalized Rouard's method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity of the minimum thickness measurement limit. Within the framework of this work, a self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wet spray in the painting process.

  16. Quantification of cell-free layer thickness and cell distribution of blood by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Lauri, Janne; Bykov, Alexander; Fabritius, Tapio

    2016-04-01

    A high-speed optical coherence tomography (OCT) with 1-μm axial resolution was applied to assess the thickness of a cell-free layer (CFL) and a spatial distribution of red blood cells (RBC) next to the microchannel wall. The experiments were performed in vitro in a plain glass microchannel with a width of 2 mm and height of 0.2 mm. RBCs were suspended in phosphate buffered saline solution at the hematocrit level of 45%. Flow rates of 0.1 to 0.5 ml/h were used to compensate gravity induced CFL. The results indicate that OCT can be efficiently used for the quantification of CFL thickness and spatial distribution of RBCs in microcirculatory blood flow.

  17. Effects of Grafting Density and Film Thickness on the Adhesion of Staphylococcus epidermidis to Poly(2-hydroxy ethyl methacrylate) and Poly(poly(ethylene glycol)methacrylate) Brushes.

    PubMed

    Ibanescu, Sorin-Alexandru; Nowakowska, Justyna; Khanna, Nina; Landmann, Regine; Klok, Harm-Anton

    2016-05-01

    Thin polymer films that prevent the adhesion of bacteria are of interest as coatings for the development of infection-resistant biomaterials. This study investigates the influence of grafting density and film thickness on the adhesion of Staphylococcus epidermidis to poly(poly(ethylene glycol)methacrylate) (PPEGMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) brushes prepared via surface-initiated atom transfer radical polymerization (SI-ATRP). These brushes are compared with poly(ethylene glycol) (PEG) brushes, which are obtained by grafting PEG onto an epoxide-modified substrate. Except for very low grafting densities (ρ = 1%), crystal violet staining experiments show that the PHEMA and PPEGMA brushes are equally effective as the PEG-modified surfaces in preventing S. epidermis adhesion and do not reveal any significant variations as a function of film thickness or grafting density. These results indicate that brushes generated by SI-ATRP are an attractive alternative to grafted-onto PEG films for the preparation of surface coatings that resist bacterial adhesion. PMID:26757483

  18. Measured Propagation Characteristics of Finite Ground Coplanar Waveguide on Silicon with a Thick Polyimide Interface Layer

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Papapolymerou, John; Tentzeris, Emmanouil M.; Williams, W. O. (Technical Monitor)

    2002-01-01

    Measured propagation characteristics of Finite Ground Coplanar (FGC) waveguide on silicon substrates with resistivities spanning 3 orders of magnitude (0.1 to 15.5 Ohm cm) and a 20 micron thick polyimide interface layer is presented as a function of the FGC geometry. Results show that there is an optimum FGC geometry for minimum loss, and silicon with a resistivity of 0.1 Ohm cm has greater loss than substrates with higher and lower resistivity. Lastly, substrates with a resistivity of 10 Ohm cm or greater have acceptable loss.

  19. The application of thick hydrogenated amorphous silicon layers to charged particle and x-ray detection

    SciTech Connect

    Perez-Mendez, V.; Cho, G.; Fujieda, I.; Kaplan, S.N.; Qureshi, S.; Street, R.A.

    1989-04-01

    We outline the characteristics of thick hydrogenated amorphous silicon layers which are optimized for the detection of charged particles, x-rays and ..gamma..-rays. Signal amplitude as a function of the linear energy transfer of various particles are given. Noise sources generated by the detector material and by the thin film electronics - a-Si:H or polysilicon proposed for pixel position sensitive detectors readout are described, and their relative amplitudes are calculated. Temperature and neutron radiation effects on leakage currents and the corresponding noise changes are presented. 17 refs., 12 figs., 2 tabs.

  20. Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

    NASA Astrophysics Data System (ADS)

    Sun, R. X.; Zheng, J.; Liao, X. L.; Che, T.; Gou, Y. F.; He, D. B.; Deng, Z. G.

    2014-10-01

    A double-layer high-temperature superconductor (HTSC) arrangement was proposed and proved to be able to bring improvements to both levitation force and guidance force compared with present single-layer HTSC arrangement. To fully exploit the applied magnetic field by a magnetic rail, the thickness dependence of a double-layer HTSC arrangement on the levitation performance was further investigated in the paper. In this study, the lower-layer bulk was polished step by step to different thicknesses, and the upper-layer bulk with constant thickness was directly superimposed on the lower-layer one. The levitation force and the force relaxation of the double-layer HTSC arrangement were measured above a Halbach magnetic rail. Experimental result shows that a bigger levitation force and a less levitation force decay could be achieved by optimizing the thickness of the lower-layer bulk HTSC. This thickness optimization method could be applied together with former reported double-layer HTSC arrangement method with aligned growth sector boundaries pattern. This series of study on the optimized combination method do bring a significant improvement on the levitation performance of present HTS maglev systems.

  1. Reflectance Decreases before Thickness Changes in the Retinal Nerve Fiber Layer in Glaucomatous Retinas

    PubMed Central

    Zhou, Ye; Kong, Wei; Knighton, Robert W.

    2011-01-01

    Purpose. Glaucoma damages the retinal never fiber layer (RNFL). RNFL thickness, measured with optical coherence tomography (OCT), is often used in clinical assessment of the damage. In this study the relation between the RNFL reflectance and thickness at early stages of glaucoma was investigated. Methods. A rat model of glaucoma was used that involved laser photocoagulation of the trabecular meshwork. The reflectance of the RNFL in an isolated retina was measured, followed by immunohistochemical staining of the axonal cytoskeleton. RNFL thickness was measured by confocal fluorescence imaging. RNFL reflectance was calculated for bundle areas located at radii of 0.22, 0.33, and 0.44 mm from the optic nerve head (ONH) center. Linear regression was used to study the relation between reflectance and thickness. For glaucomatous eyes, only those bundles with no apparent structural damage were used. Results. Bundles in 11 control retinas and 10 treated retinas were examined. Bundle thickness of both groups at each radius was similar (P = 0.89). The reflectance of the bundles at radii of 0.33 and 0.44 mm was found to be similar in both control and treated retinas (P > 0.5). However, the reflectance of the bundles at the 0.22-mm radius decreased significantly in the treated group (P = 0.005). Conclusions. Elevation of intraocular pressure causes decrease in RNFL reflectance for bundles near the ONH. Change in RNFL reflectance precedes thinning of the RNFL. The results suggest that a decrease in RNFL reflectance near the ONH is an early sign of glaucomatous damage. PMID:21730345

  2. Spatial coherence effect on layer thickness determination in narrowband full-field optical coherence tomography

    SciTech Connect

    Safrani, Avner; Abdulhalim, Ibrahim

    2011-06-20

    Longitudinal spatial coherence (LSC) is determined by the spatial frequency content of an optical beam. The use of lenses with a high numerical aperture (NA) in full-field optical coherence tomography and a narrowband light source makes the LSC length much shorter than the temporal coherence length, hence suggesting that high-resolution 3D images of biological and multilayered samples can be obtained based on the low LSC. A simplified model is derived, supported by experimental results, which describes the expected interference output signal of multilayered samples when high-NA lenses are used together with a narrowband light source. An expression for the correction factor for the layer thickness determination is found valid for high-NA objectives. Additionally, the method was applied to a strongly scattering layer, demonstrating the potential of this method for high-resolution imaging of scattering media.

  3. Anatomy and physiology of the thick-tufted layer 5 pyramidal neuron

    PubMed Central

    Ramaswamy, Srikanth; Markram, Henry

    2015-01-01

    The thick-tufted layer 5 (TTL5) pyramidal neuron is one of the most extensively studied neuron types in the mammalian neocortex and has become a benchmark for understanding information processing in excitatory neurons. By virtue of having the widest local axonal and dendritic arborization, the TTL5 neuron encompasses various local neocortical neurons and thereby defines the dimensions of neocortical microcircuitry. The TTL5 neuron integrates input across all neocortical layers and is the principal output pathway funneling information flow to subcortical structures. Several studies over the past decades have investigated the anatomy, physiology, synaptology, and pathophysiology of the TTL5 neuron. This review summarizes key discoveries and identifies potential avenues of research to facilitate an integrated and unifying understanding on the role of a central neuron in the neocortex. PMID:26167146

  4. Realizing the full potential of Remotely Sensed Active Layer Thickness (ReSALT) Products

    NASA Astrophysics Data System (ADS)

    Schaefer, K. M.; Chen, A.; Liu, L.; Parsekian, A.; Jafarov, E. E.; Panda, S. K.; Zebker, H. A.

    2015-12-01

    The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence, active layer thickness (ALT), and thermokarst activity in permafrost regions. ReSALT supports research for the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential Nasa-Isro Synthetic Aperture Radar (NISAR) product. ALT is a critical parameter for monitoring the status of permafrost and thermokarst activity is one of the key drivers of change in permafrost regions. The ReSALT product currently includes 1) long-term subsidence trends resulting from the melting and subsequent drainage of excess ground ice in permafrost-affected soils, 2) seasonal subsidence resulting from the expansion of soil water into ice as the active layer freezes and thaws, and 3) ALT estimated from the seasonal subsidence assuming a vertical profile of water within the soil column. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. We present high resolution ReSALT products on the North Slope of Alaska: Prudhoe Bay, Barrow, Toolik Lake, Happy Valley, and the Anaktuvuk fire zone. We believe that the ReSALT product could be expanded to include maps of individual thermokarst features identified as spatial anomalies in the subsidence trends, with quantified expansion rates. We illustrate the technique with multiple examples of thermokarst features on the North Slope of Alaska. Knowing the locations and expansion rates for individual features allows us to evaluate risks to human infrastructure. Our results highlight the untapped potential of the InSAR technique to remotely sense ALT and thermokarst dynamics over large areas of the Arctic.

  5. Enhancement of adhesion by a transition layer: Deposition of a-C film on ultrahigh molecular weight polyethylene (UHMWPE) by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    He, F. F.; Bai, W. Q.; Li, L. L.; Wang, X. L.; Xie, Y. J.; Jin, G.; Tu, J. P.

    2016-02-01

    An amorphous carbon (a-C) film is deposited on the plasma-treated UHMWPE substrate using a closed field unbalanced magnetron sputtering to improve its tribological properties. During the plasma treatment period, a transition layer is prepared by high energy ion bombardment at a bias voltage of -500 V to enhance the adhesion between the a-C film and the substrate. The mechanical and tribological properties of the a-C film were evaluated by nano-indentation and ball-on-disk tribometer. After deposition of a-C film with a thickness 900 nm, the nano-hardness of UHMWPE significantly increases from 47 MPa to 720 MPa and the wear rate decreases from 9.82 × 10-15 m3 N-1 m-1 to 4.78 × 10-15 m3 N-1 m-1 in bovine calf serum solution. The formation of the transition layer is believed to be the reason why the vertical adhesion between the a-C film and the UHMWPE substrate is enhanced.

  6. Changes in Inner and Outer Retinal Layer Thicknesses after Vitrectomy for Idiopathic Macular Hole: Implications for Visual Prognosis

    PubMed Central

    Hashimoto, Yuki; Saito, Wataru; Fujiya, Akio; Yoshizawa, Chikako; Hirooka, Kiriko; Mori, Shohei; Noda, Kousuke; Ishida, Susumu

    2015-01-01

    Purpose To investigate sequential post-operative thickness changes in inner and outer retinal layers in eyes with an idiopathic macular hole (MH). Methods Retrospective case series. Twenty-four eyes of 23 patients who had received pars plana vitrectomy (PPV) for the closure of MH were included in the study. Spectral domain optical coherence tomography C-scan was used to automatically measure the mean thickness of the inner and outer retinal layers pre-operatively and up to 6 months following surgery. The photoreceptor outer segment (PROS) length was measured manually and was used to assess its relationship with best-corrected visual acuity (BCVA). Results Compared with the pre-operative thickness, the inner layers significantly thinned during follow-up (P = 0.02), particularly in the parafoveal (P = 0.01), but not perifoveal, area. The post-operative inner layer thinning ranged from the ganglion cell layer to the inner plexiform layer (P = 0.002), whereas the nerve fiber layer was unaltered. Outer layer thickness was significantly greater post-operatively (P = 0.002), and especially the PROS lengthened not only in the fovea but also in the parafovea (P < 0.001). Six months after surgery, BCVA was significantly correlated exclusively with the elongated foveal PROS (R = 0.42, P = 0.03), but not with any of the other thickness parameters examined. Conclusions Following PPV for MH, retinal inner layers other than the nerve fiber layer thinned, suggestive of subclinical thickening in the inner layers where no cyst was evident pre-operatively. In contrast, retinal outer layer thickness significantly increased, potentially as a result of PROS elongation linking tightly with favorable visual prognosis in MH eyes. PMID:26291526

  7. Lubiprostone Decreases Mouse Colonic Inner Mucus Layer Thickness and Alters Intestinal Microbiota

    PubMed Central

    Musch, Mark W.; Wang, Yunwei; Claud, Erika C.

    2013-01-01

    Background Lubiprostone has been used to treat constipation through its effects to stimulate Cl− secretion, resulting in water and electrolyte secretion. Aim Potential associated changes in intestinal mucus and the colonizing bacteria (microbiome) have not been studied. As mucus obstructions may play a role in cystic fibrosis, the hypothesis that lubiprostone alters intestinal mucus and the microbiome was investigated. Methods Ion transport studies were performed ex vivo. For mucus and microbiome studies, mice were gavaged daily with lubiprostone or vehicle. Mucin from intestinal sections was analyzed in Carnoy’s fixed tissues stained with Alcian blue. Microbiome composition was analyzed by 16S rRNA gene-based sequencing. Results Lubiprostone stimulated short circuit current in all mouse intestinal segments after both serosal and mucosal additions, albeit at lower concentrations in the latter. Current was Cl-dependent and blocked by mucosal diphenylcarboxylic acid, serosal bumetanide, and serosal Ba++. The CFTR inhibitor CFTRinh172 had a marginal effect. Mucus near epithelial cells (inner layer mucus) was not present in the small intestine of any mice. Proximal colon inner mucus layer was thicker in ΔF/ΔF compared with +/ΔF and +/+ mice. Lubiprostone decreased inner mucus layer thickness in both proximal and distal colon of all mice. Furthermore, lubiprostone altered the intestinal microbiome by increasing abundance of Lactobacillus and Alistipes. Conclusions Lubiprostone activates non-CFTR Cl− secretion and alters the colonic inner mucus layer, which is associated with changes in the composition of the enteric microbiome. PMID:23329012

  8. Properties of single shear layer instabilities and vortex-induced excitation mechanisms of thick plates

    NASA Astrophysics Data System (ADS)

    Billeter, P.

    2004-04-01

    The basic findings of an experimental investigation of flow-induced vibrations of gate plates with multiple degrees of freedom are presented. The study focused on the fluid dynamic behaviour of the single shear layer separating from a thick rectangular plate. The principal aim of the study was to further the physical understanding of instability-induced excitation mechanisms (IIE) involving shear layer instabilities and vortex generation. It is shown that this type of gate vibration is caused by two dominant excitation mechanisms: cross-flow and streamwise impinging-leading-edge-vortex (ILEV) excitation and streamwise body-resonant leading-edge-vortex-shedding (BR-LEVS) excitation. The first mechanism is caused by the local interaction of the shear layer underneath the gate plate with the trailing edge of the gate lip. The second mechanism is produced by the instability of the shear layer in the tailwater of the gate, with the instability being necessarily triggered by the elastic motion of the flow separation at the leading edge of the gate. Former address. Laboratory of Hydraulics (VAW), Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.

  9. A procedure to mathematically amend possible thickness disuniformities in gel-layer dosimetry

    NASA Astrophysics Data System (ADS)

    Carrara, Mauro; Gambarini, Grazia; Bartesaghi, Giacomo; Fallai, Carlo; Negri, Anna

    2009-05-01

    The continuous development of conformal radiotherapies requires a corresponding improvement of dosimetric techniques. Fricke gel-layer dosimetry, coupled with a suitably developed software, has proven to be a reliable technique for 3D absorbed dose distribution verification. The method is based on the evaluation of the light transmitted by gel-layers due to the fact that th optical density difference between irradiated and non irraddiated dosimeters is proportional to the absorbed dose. Measurement are performed by means of a planar illumination source and a computer-controlled CCD camera. Recently, adoption of gel layers with increased superficial dimensions has evidenced a possible thickness disuniformity of layers, thus introducing a new source of measurement inaccuracy. In this work, a method to mathematically amend this possible source of error is proposed. Dose profiles along the central axis of phantoms irradiated with X-ray therapy and Boron Neutron Capture Therapy fields, obtained with and without the application of the proposed correction procedure, were compared with ionization chamber measurements and Monte Carlo simulations, respectively. The obtained results show a good reliability of the proposed procedure.

  10. Optimization of electrode geometry and piezoelectric layer thickness of a deformable mirror

    NASA Astrophysics Data System (ADS)

    Kruchenko, Alexey V.; Nováková, Kateřina; Mokrý, Pavel

    2013-04-01

    Deformable mirrors are the most commonly used wavefront correctors in adaptive optics systems. Nowadays, many applications of adaptive optics to astronomical telescopes, high power laser systems, and similar fast response optical devices require large diameter deformable mirrors with a fast response time and high actuator stroke. In order to satisfy such requirements, deformable mirrors based on piezoelectric layer composite structures have become a subject of intense scientific research during last two decades. In this paper, we present an optimization of several geometric parameters of a deformable mirror that consists of a nickel reflective layer deposited on top of a thin lead zirconate titanate (PZT) piezoelectric disk. Honeycomb structure of gold electrodes is deposited on the bottom of the PZT layer. The analysis of the optimal thickness ratio between the PZT and nickel layers is performed to get the maximum actuator stroke using the finite element method. The effect of inter-electrode distance on the actuator stroke and influence function is investigated. Applicability and manufacturing issues are discussed.

  11. Characterization of the plastic substrates, the reflective layers, the adhesives, and the grooves of today's archival-grade recordable DVDs

    SciTech Connect

    Jiang, Guilin; Rivera, Felipe; Kanyal, Supriya S.; Davis, Robert C.; Vanfleet, Richard; Lunt, Barry M.; Shutthanandan, V.; Linford, Matthew R.

    2011-01-01

    The plastic substrates, reflective layers, dyes, and adhesives of four archival-grade DVDs and one standard-grade recordable DVD were analyzed to determine their chemical compositions and/or physical dimensions. Chemical analyses by ATR-FTIR, ToF-SIMS, XPS, EDX/STEM, and RBS show that all these DVDs use very similar polycarbonate plastic substrates and acrylate-based adhesives, but different reflective layers and dye write layers. In addition, physical measurements by AFM show differences in the DVD groove depth, width, and other dimensions. These chemical and physical analyses may help explain variations in DVD lifetimes and facilitate development of the next generation of archival-grade DVDs.

  12. Peripapillary retinal nerve fiber layer thickness in patients with iron deficiency anemia

    PubMed Central

    Cikmazkara, Ipek; Ugurlu, Seyda Karadeniz

    2016-01-01

    Purpose: To evaluate the effect of iron deficiency anemia (IDA) on peripapillary retinal nerve fiber layer (RNFL) thickness with optical coherence tomography (OCT). Materials and Methods: 102 female patients who had IDA (hemoglobin <12 g/dl, serum transferrin saturation <15%, serum iron <50 μg/dl, and serum ferritin <15 μg/dl) were enrolled in the study. Optic disc and RNFL parameters obtained by Cirrus high-definition OCT 4000 were compared with those of 49 age and sex-matched nonanemic individuals. The time between blood analysis and OCT measurements was 3.14 ± 5.6 (range, 0–28) days in the anemia group, and 3.5 ± 6.7 (range, 0–27) days in the control group (P = 0.76). Results: Average ages of 102 patients and 49 control subjects were 35.76 ± 10.112 (range, 18–66) years, and 36.08 ± 8.416 (range, 19–57) years (P = 0.850), respectively. The average RNFL thickness was 94.67 ± 9.380 in the anemia group, and 100.22 ± 9.12 in the control group (P = 0.001). Temporal, nasal, and lower quadrant average RNFL thicknesses of IDA group were thinner than the control group (P = 0.001, P = 0.013, P = 0.008). Upper quadrant RNFL thicknesses in IDA and control groups were similar. Correlation analysis revealed positive correlation between mean RNFL thickness and hemoglobin (r = 0.273), iron (r = 0.177), ferritin (r = 0.163), and transferrin saturations (r = 0.185), while a negative correlation was found between total iron binding capacity (r = −0.199) and mean RNFL thickness. Conclusions: Peripapillary RNFL thickness measured by OCT is thinner in adult female patients with IDA. It may have a significant influence on the management of many disorders such as glaucoma and neuro-ophthalmological diseases. PMID:27146929

  13. Elastic-plastic analysis of crack in ductile adhesive joint

    SciTech Connect

    Ikeda, Toru; Miyazaki, Noriyuki; Yamashita, Akira; Munakata, Tsuyoshi

    1995-11-01

    The fracture of a crack in adhesive is important to the structural integrity of adhesive structures and composite materials. Though the fracture toughness of a material should be constant according to fracture mechanics, it is said that the fracture toughness of a crack in an adhesive joint depends on the bond thickness. In the present study, the elastic-plastic stress analyses of a crack in a thin adhesive layer are performed by the combination of the boundary element method and the finite element method. The effect of adhesive thickness on the J-integral, the Q`-factor which is a modified version of the Q-factor, and the crack tip opening displacement (CTOD) are investigated. It is found from the analyses that the CTOD begins to decrease at very thin bond thickness, the Q`-factor being almost constant. The decrease of the fracture toughness at very thin adhesive layer is expected by the present analysis.

  14. Thickness-dependent charge transport in few-layer MoS2 field-effect transistors

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Wei; Kravchenko, Ivan I.; Fowlkes, Jason; Li, Xufan; Puretzky, Alexander A.; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

    2016-04-01

    Molybdenum disulfide (MoS2) is currently under intensive study because of its exceptional optical and electrical properties in few-layer form. However, how charge transport mechanisms vary with the number of layers in MoS2 flakes remains unclear. Here, exfoliated flakes of MoS2 with various thicknesses were successfully fabricated into field-effect transistors (FETs) to measure the thickness and temperature dependences of electrical mobility. For these MoS2 FETs, measurements at both 295 K and 77 K revealed the maximum mobility for layer thicknesses between 5 layers (˜3.6 nm) and 10 layers (˜7 nm), with ˜70 cm2 V-1 s-1 measured for 5 layer devices at 295 K. Temperature-dependent mobility measurements revealed that the mobility rises with increasing temperature to a maximum. This maximum occurs at increasing temperature with increasing layer thickness, possibly due to strong Coulomb scattering from charge impurities or weakened electron-phonon interactions for thicker devices. Temperature-dependent conductivity measurements for different gate voltages revealed a metal-to-insulator transition for devices thinner than 10 layers, which may enable new memory and switching applications. This study advances the understanding of fundamental charge transport mechanisms in few-layer MoS2, and indicates the promise of few-layer transition metal dichalcogenides as candidates for potential optoelectronic applications.

  15. Thickness-dependent charge transport in few-layer MoS2 field-effect transistors.

    PubMed

    Lin, Ming-Wei; Kravchenko, Ivan I; Fowlkes, Jason; Li, Xufan; Puretzky, Alexander A; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2016-04-22

    Molybdenum disulfide (MoS2) is currently under intensive study because of its exceptional optical and electrical properties in few-layer form. However, how charge transport mechanisms vary with the number of layers in MoS2 flakes remains unclear. Here, exfoliated flakes of MoS2 with various thicknesses were successfully fabricated into field-effect transistors (FETs) to measure the thickness and temperature dependences of electrical mobility. For these MoS2 FETs, measurements at both 295 K and 77 K revealed the maximum mobility for layer thicknesses between 5 layers (∼3.6 nm) and 10 layers (∼7 nm), with ∼70 cm(2) V(-1) s(-1) measured for 5 layer devices at 295 K. Temperature-dependent mobility measurements revealed that the mobility rises with increasing temperature to a maximum. This maximum occurs at increasing temperature with increasing layer thickness, possibly due to strong Coulomb scattering from charge impurities or weakened electron-phonon interactions for thicker devices. Temperature-dependent conductivity measurements for different gate voltages revealed a metal-to-insulator transition for devices thinner than 10 layers, which may enable new memory and switching applications. This study advances the understanding of fundamental charge transport mechanisms in few-layer MoS2, and indicates the promise of few-layer transition metal dichalcogenides as candidates for potential optoelectronic applications. PMID:26963583

  16. Bond Strength of a Bisphenol-A-Free Fissure Sealant With and Without Adhesive Layer under Conditions of Saliva Contamination.

    PubMed

    Mesquita-Guimarães, Késsia Suênia Fidelis de; Sabbatini, Iliana Ferraz; Almeida, Cintia Guimarães de; Galo, Rodrigo; Nelson-Filho, Paulo; Borsatto, Maria Cristina

    2016-01-01

    Dental sealants are important for prevention of carious lesions, if they have good shear strength. The aim of this study was to evaluate the shear bond strength (SBS) of two sealants to saliva-contaminated and non-contaminated enamel with and without an intermediate adhesive layer underneath the sealant. Ninety flat enamel surfaces from human third molars were randomly assigned to 6 groups (n=15): F (control): Fluroshield(tm) sealant; EWB (control): Embrace(tm) WetBond(tm); SB/F: Single Bond adhesive system + F; SB/EWB, s-SB/F and s-SB/EWB. In the s-SB/F and s-SB/EWB groups, the acid-etched enamel was contaminated with 0.01 mL of fresh human saliva for 20 s. Sealant cylinders were bonded to enamel surface with and without an intermediate adhesive system layer. The shear tests were performed using a universal testing machine (0.5 mm/min). Data were analyzed statistically by Kruskal-Wallis and Mann-Whitney tests (α=0.05). F presented higher mean SBS than EWB in all experimental conditions. The lowest SBS mean was obtained for EWB on contaminated enamel (p<0.05). In conclusion, an adhesive system layer should be used prior to sealant placement, in both dry and saliva-contaminated enamel. F had the best performance in all experimental conditions. EWB sealant showed very low results, but an adhesive layer underneath the sealant increased its SBS even after salivary contamination. PMID:27224565

  17. Moderately large vibrations of doubly curved shallow open shells composed of thick layers

    NASA Astrophysics Data System (ADS)

    Adam, Christoph

    2007-02-01

    This paper addresses nonlinear flexural vibrations of shallow shells composed of three thick layers with different shear flexibility, which are symmetrically arranged with respect to the middle surface. The considered shell structures of polygonal planform are hard hinged simply supported (i.e. all in-plane rotations and the bending moment vanish) with the edges fully restraint against displacements in any direction. The kinematic field equations are formulated by layerwise application of a first-order shear deformation theory. A modification of Berger's theory is employed to model the nonlinear characteristics of the structural response. The continuity of the transverse shear stress across the interfaces is specified according to Hooke's law, and subsequently the equations of motion of this higher order problem can be derived in analogy to a homogeneous single-layer shear deformable shallow shell. Numerical results of rectangular shallow shells in nonlinear steady-state vibration are presented for various ratios of shell rise to thickness, and non-dimensional load amplitude.

  18. Effect of optic nerve sheath fenestration for idiopathic intracranial hypertension on retinal nerve fiber layer thickness.

    PubMed

    Starks, Victoria; Gilliland, Grant; Vrcek, Ivan; Gilliland, Connor

    2016-01-01

    The objective of the study was to evaluate whether optic nerve sheath fenestration in patients with idiopathic intracranial hypertension was associated with improvement in visual field pattern deviation and optical coherence tomography retinal nerve fiber layer thickness.The records of 13 eyes of 11 patients who underwent optic nerve sheath fenestration were reviewed. The subjects were patients of a clinical practice in Dallas, Texas. Charts were reviewed for pre- and postoperative visual field pattern deviation (PD) and retinal nerve fiber layer thickness (RNFL).PD and RNFL significantly improved after surgery. Average PD preoperatively was 8.51 DB and postoperatively was 4.80 DB (p = 0.0002). Average RNFL preoperatively was 113.63 and postoperatively was 102.70 (p = 0.01). The preoperative PD and RNFL did not correlate strongly.Our results demonstrate that PD and RNFL are improved after optic nerve sheath fenestration. The pre- and postoperative RNFL values were compared to the average RNFL value of healthy optic nerves obtained from the literature. Post-ONSF RNFL values were significantly closer to the normal value than preoperative. RNFL is an objective parameter for monitoring the optic nerve after optic nerve sheath fenestration. This study adds to the evidence that OCT RNFL may be an effective monitoring tool for patients with IIH and that it continues to be a useful parameter after ONSF. PMID:26928128

  19. Area-Selective Atomic Layer Deposition: Conformal Coating, Subnanometer Thickness Control, and Smart Positioning.

    PubMed

    Fang, Ming; Ho, Johnny C

    2015-09-22

    Transistors have already been made three-dimensional (3D), with device channels (i.e., fins in trigate field-effect transistor (FinFET) technology) that are taller, thinner, and closer together in order to enhance device performance and lower active power consumption. As device scaling continues, these transistors will require more advanced, fabrication-enabling technologies for the conformal deposition of high-κ dielectric layers on their 3D channels with accurate position alignment and thickness control down to the subnanometer scale. Among many competing techniques, area-selective atomic layer deposition (AS-ALD) is a promising method that is well suited to the requirements without the use of complicated, complementary metal-oxide semiconductor (CMOS)-incompatible processes. However, further progress is limited by poor area selectivity for thicker films formed via a higher number of ALD cycles as well as the prolonged processing time. In this issue of ACS Nano, Professor Stacy Bent and her research group demonstrate a straightforward self-correcting ALD approach, combining selective deposition with a postprocess mild chemical etching, which enables selective deposition of dielectric films with thicknesses and processing times at least 10 times larger and 48 times shorter, respectively, than those obtained by conventional AS-ALD processes. These advances present an important technological breakthrough that may drive the AS-ALD technique a step closer toward industrial applications in electronics, catalysis, and photonics, etc. where more efficient device fabrication processes are needed. PMID:26351731

  20. Coupled annealing temperature and layer thickness effect on strengthening mechanisms of Ti/Ni multilayer thin films

    NASA Astrophysics Data System (ADS)

    Yang, Zhou; Wang, Junlan

    2016-03-01

    A systematic study was performed on mechanical and microstructural properties of Ti/Ni multilayers with layer thickness from 200 nm to 6 nm and annealing temperature from room temperature to 500 °C. Based on the observed hardness evolution, a coupled layer-thickness and annealing-temperature dependent strengthening mechanism map is proposed. For as-deposited films, the deformation behavior follows the traditional trend of dislocation mediated strengthening to grain boundary mediated softening with decreasing layer thickness. For annealed films, grain boundary relaxation is considered to be the initial strengthening mechanism with higher activation temperature required for thicker layers. Under further annealing, solid solution hardening, intermetallic precipitation hardening, and fully intermixed alloy structure continue to strengthen the thin layered films, while recrystallization and grain-growth lead to the eventual softening of thick layered films. For the films with intermediate layer thickness, a strong orientation dependent hardness behavior is exhibited under high temperature annealing due to mechanism switch from grain growth softening to intermetallic precipitation hardening when changing the loading orientation from perpendicular to parallel to the layer interfaces.

  1. Strain relaxation of thick (11–22) semipolar InGaN layer for long wavelength nitride-based device

    SciTech Connect

    Kim, Jaehwan; Min, Daehong; Jang, Jongjin; Lee, Kyuseung; Chae, Sooryong; Nam, Okhyun

    2014-10-28

    In this study, the properties of thick stress-relaxed (11–22) semipolar InGaN layers were investigated. Owing to the inclination of growth orientation, misfit dislocations (MDs) occurred at the heterointerface when the strain state of the (11–22) semipolar InGaN layers reached the critical point. We found that unlike InGaN layers based on polar and nonpolar growth orientations, the surface morphologies of the stress-relaxed (11–22) semipolar InGaN layers did not differ from each other and were similar to the morphology of the underlying GaN layer. In addition, misfit strain across the whole InGaN layer was gradually relaxed by MD formation at the heterointerface. To minimize the effect of surface roughness and defects in GaN layers on the InGaN layer, we conducted further investigation on a thick (11–22) semipolar InGaN layer grown on an epitaxial lateral overgrown GaN template. We found that the lateral indium composition across the whole stress-relaxed InGaN layer was almost uniform. Therefore, thick stress-relaxed (11–22) semipolar InGaN layers are suitable candidates for use as underlying layers in long-wavelength devices, as they can be used to control strain accumulation in the heterostructure active region without additional influence of surface roughness.

  2. Sodium chloride crystallization from thin liquid sheets, thick layers, and sessile drops in microgravity

    NASA Astrophysics Data System (ADS)

    Fontana, Pietro; Pettit, Donald; Cristoforetti, Samantha

    2015-10-01

    Crystallization from aqueous sodium chloride solutions as thin liquid sheets, 0.2-0.7 mm thick, with two free surfaces supported by a wire frame, thick liquid layers, 4-6 mm thick, with two free surfaces supported by metal frame, and hemispherical sessile drops, 20-32 mm diameter, supported by a flat polycarbonate surface or an initially flat gelatin film, were carried out under microgravity on the International Space Station (ISS). Different crystal morphologies resulted based on the fluid geometry: tabular hoppers, hopper cubes, circular [111]-oriented crystals, and dendrites. The addition of polyethylene glycol (PEG-3350) inhibited the hopper growth resulting in flat-faced surfaces. In sessile drops, 1-4 mm tabular hopper crystals formed on the free surface and moved to the fixed contact line at the support (polycarbonate or gelatin) self-assembling into a shell. Ring formation created by sessile drop evaporation to dryness was observed but with crystals 100 times larger than particles in terrestrially formed coffee rings. No hopper pyramids formed. By choosing solution geometries offered by microgravity, we found it was possible to selectively grow crystals of preferred morphologies.

  3. Hydration and chain entanglement determines the optimum thickness of poly(HEMA-co-PEG₁₀MA) brushes for effective resistance to settlement and adhesion of marine fouling organisms.

    PubMed

    Yandi, Wetra; Mieszkin, Sophie; Martin-Tanchereau, Pierre; Callow, Maureen E; Callow, James A; Tyson, Lyndsey; Liedberg, Bo; Ederth, Thomas

    2014-07-23

    Understanding how surface physicochemical properties influence the settlement and adhesion of marine fouling organisms is important for the development of effective and environmentally benign marine antifouling coatings. We demonstrate that the thickness of random poly(HEMA-co-PEG10MA) copolymer brushes affect antifouling behavior. Films of thicknesses ranging from 50 to 1000 Å were prepared via surface-initiated atom-transfer radical polymerization and characterized using infrared spectroscopy, ellipsometry, atomic force microscopy and contact angle measurements. The fouling resistance of these films was investigated by protein adsorption, attachment of the marine bacterium Cobetia marina, settlement and strength of attachment tests of zoospores of the marine alga Ulva linza and static immersion field tests. These assays show that the polymer film thickness influenced the antifouling performance, in that there is an optimum thickness range, 200-400 Å (dry thickness), where fouling of all types, as well as algal spore adhesion, was lower. Field test results also showed lower fouling within the same thickness range after 2 weeks of immersion. Studies by quartz crystal microbalance with dissipation and underwater captive bubble contact angle measurements show a strong correlation between lower fouling and higher hydration, viscosity and surface energy of the poly(HEMA-co-PEG10MA) brushes at thicknesses around 200-400 Å. We hypothesize that the reduced antifouling performance is caused by a lower hydration capacity of the polymer for thinner films, and that entanglement and crowding in the film reduces the conformational freedom, hydration capacity and fouling resistance for thicker films. PMID:24945705

  4. Optical in-situ monitoring system for simultaneous measurement of thickness and curvature of thick layer stacks during hydride vapor phase epitaxy growth of GaN

    NASA Astrophysics Data System (ADS)

    Semmelroth, K.; Berwian, P.; Schröter, C.; Leibiger, G.; Schönleber, M.; Friedrich, J.

    2015-10-01

    For improved real-time process control we integrated a novel optical in-situ monitoring system in a vertical reactor for hydride vapor phase epitaxy (HVPE) growth of gallium nitride (GaN) bulk crystals. The in-situ monitoring system consists of a fiber-optical interferometric sensor in combination with an optimized differential measuring head. The system only needs one small optical path perpendicular to the center of the layer stack typically consisting of sapphire as substrate and GaN. It can handle sample distances up to 1 m without difficulty. The in-situ monitoring system is simultaneously measuring the optical layer thicknesses of the GaN/sapphire layer stack and the absolute change of the distance between the measuring head and the backside of the layer stack. From this data it is possible to calculate the thickness of the growing GaN up to a thickness of about 1000 μm and the absolute change in curvature of the layer stack. The performance of the in-situ monitoring system is shown and discussed based on the measured interference signals recorded during a short-time and a long-time HVPE growth run.

  5. Effect of pectin on jejunal glucose absorption and unstirred layer thickness in normal man.

    PubMed Central

    Flourie, B; Vidon, N; Florent, C H; Bernier, J J

    1984-01-01

    The effect of high methoxy apple pectin, a carbohydrate gelling agent, on the intestinal absorption of glucose, water, and sodium was studied in man. The effect of intraluminal fibre was evaluated in 22 healthy volunteers by the intestinal perfusion technique under an occlusive balloon. The test solutions (NaCl 130 mM, KCl 5 mM, glucose or mannitol 30 mM, PEG 4000 5 g/l) were perfused just beyond the ligament of Treitz at a rate of 10 ml/min. A 25 cm segment was studied. Three concentrations of pectin were tested: 6, 10, and 15 g/l. The effect of this pectin at two concentrations, 6 and 10 g/l, on the jejunal unstirred layer thickness was evaluated in nine other healthy subjects by an electrical technique. In mannitol solution, pectin reversed water and sodium absorption, whatever its concentration was, while in glucose solution it significantly reduced absorption of water and sodium at 10 and 15 g/l only (p less than 0.01). It significantly reduced glucose absorption at all concentrations (p less than 0.01). This reduction was found to be correlated with the solution viscosity (p less than 0.01). Pectin did not alter the glucose dependent sodium transport but increased significantly (p less than 0.001) the unstirred layer thickness. These results suggested that, in healthy man, pectin acutely given may impair intestinal absorption by means of an increased unstirred layer resistance. This effect could contribute to the diminished postprandial glycaemia observed in human subjects fed pectin. PMID:6432635

  6. Effect of pectin on jejunal glucose absorption and unstirred layer thickness in normal man.

    PubMed

    Flourie, B; Vidon, N; Florent, C H; Bernier, J J

    1984-09-01

    The effect of high methoxy apple pectin, a carbohydrate gelling agent, on the intestinal absorption of glucose, water, and sodium was studied in man. The effect of intraluminal fibre was evaluated in 22 healthy volunteers by the intestinal perfusion technique under an occlusive balloon. The test solutions (NaCl 130 mM, KCl 5 mM, glucose or mannitol 30 mM, PEG 4000 5 g/l) were perfused just beyond the ligament of Treitz at a rate of 10 ml/min. A 25 cm segment was studied. Three concentrations of pectin were tested: 6, 10, and 15 g/l. The effect of this pectin at two concentrations, 6 and 10 g/l, on the jejunal unstirred layer thickness was evaluated in nine other healthy subjects by an electrical technique. In mannitol solution, pectin reversed water and sodium absorption, whatever its concentration was, while in glucose solution it significantly reduced absorption of water and sodium at 10 and 15 g/l only (p less than 0.01). It significantly reduced glucose absorption at all concentrations (p less than 0.01). This reduction was found to be correlated with the solution viscosity (p less than 0.01). Pectin did not alter the glucose dependent sodium transport but increased significantly (p less than 0.001) the unstirred layer thickness. These results suggested that, in healthy man, pectin acutely given may impair intestinal absorption by means of an increased unstirred layer resistance. This effect could contribute to the diminished postprandial glycaemia observed in human subjects fed pectin. PMID:6432635

  7. Thickness determination of few-layer hexagonal boron nitride films by scanning electron microscopy and Auger electron spectroscopy

    SciTech Connect

    Sutter, P. Sutter, E.

    2014-09-01

    We assess scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.

  8. The optimizing designing of bi-material micro cantilever with adhesive layer in between and its application in an uncooled MEMS IR FPA

    NASA Astrophysics Data System (ADS)

    Zhang, Xia; Jiao, Bin-bin; Chen, Da-peng; Ye, Tian-chun

    2009-07-01

    Bi-material cantilever is an important basic structure in MEMS device. Most of the materials with thermal property fit for bi-material are not adhering together steadily. An adhesive layer in between is needed. In this paper, based on the thermal stress and combined deformation in Mechanics of Materials, a model related to the physics properties, structure dimension, and the tilt angle caused by thermal stress is set up. A research of how to select the materials and how to determinate the thickness and other size of a bi-material cantilever is carry out by this model, further more, an optic read out IR image chip pixel is designed that shows this model is simple and practical.

  9. Differentiation of magma oceans and the thickness of the depleted layer on Venus

    NASA Technical Reports Server (NTRS)

    Solomatov, V. S.; Stevenson, D. J.

    1993-01-01

    Various arguments suggest that Venus probably has no asthenosphere, and it is likely that beneath the crust there is a highly depleted and highly viscous mantle layer which was probably formed in the early history of the planet when it was partially or completely molten. Models of crystallization of magma oceans suggest that just after crystallization of a hypothetical magma ocean, the internal structure of Venus consists of a crust up to about 70 km thickness, a depleted layer up to about 500 km, and an enriched lower layer which probably consists of an undepleted 'lower mantle' and heavy enriched accumulates near the core-mantle boundary. Partial or even complete melting of Venus due to large impacts during the formation period eventually results in differentiation. However, the final result of such a differentiation can vary from a completely differentiated mantle to an almost completely preserved homogeneous mantle depending on competition between convection and differentiation: between low viscosity ('liquid') convection and crystal settling at small crystal fractions, or between high viscosity ('solid') convection and percolation at large crystal fractions.

  10. Charge transport in thick SiO 2-based dielectric layers

    NASA Astrophysics Data System (ADS)

    Kanitz, Sven

    1997-12-01

    Charge transport in thick (≥ 1 μm) SiO 2-based dielectric layers was investigated by means of I( U) measurements. Investigations were carried out on thermally grown field oxide (FOX) as well as on TEOS and BPSG. Gate oxide layers (GOX) were measured as reference. C( U) measurements were performed for the determination of charges in the oxide. To determine the electrical parameters of the layers, the model from Chen and Wu[1] was developed further. The model takes into account tunnelling, capture and emission processes, impact ionization, recombination, interface states and ohmic currents. The I( U) characteristics for all dielectrics examined can be described with the aid of the model. The FOX parameters correspond to those of GOX. The parameters of TEOS and BPSG fluctuate strongly with the process parameters. After high-temperature annealing and from measurement of the examined parameters, the insulation properties of TEOS and BPSG were found to be at least as good as those of FOX.

  11. Tissue-engineered endothelial cell layers on surface-modified Ti for inhibiting in vitro platelet adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Xiupeng; He, Fupo; Li, Xia; Ito, Atsuo; Sogo, Yu; Maruyama, Osamu; Kosaka, Ryo; Ye, Jiandong

    2013-06-01

    A tissue-engineered endothelial layer was prepared by culturing endothelial cells on a fibroblast growth factor-2 (FGF-2)-l-ascorbic acid phosphate magnesium salt n-hydrate (AsMg)-apatite (Ap) coated titanium plate. The FGF-2-AsMg-Ap coated Ti plate was prepared by immersing a Ti plate in supersaturated calcium phosphate solutions supplemented with FGF-2 and AsMg. The FGF-2-AsMg-Ap layer on the Ti plate accelerated proliferation of human umbilical vein endothelial cells (HUVECs), and showed slightly higher, but not statistically significant, nitric oxide release from HUVECs than on as-prepared Ti. The endothelial layer maintained proper function of the endothelial cells and markedly inhibited in vitro platelet adhesion. The tissue-engineered endothelial layer formed on the FGF-2-AsMg-Ap layer is promising for ameliorating platelet activation and thrombus formation on cardiovascular implants.

  12. Protein adsorption on poly(N-isopropylacrylamide)-modified silicon surfaces: effects of grafted layer thickness and protein size.

    PubMed

    Yu, Qian; Zhang, Yanxia; Chen, Hong; Wu, Zhaoqiang; Huang, He; Cheng, Chi

    2010-04-01

    In this work, we investigated the protein adsorption on the end-tethered thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) brushes with varying grafted layer thickness prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized silicon surfaces. The thickness of a grafted layer was modulated by adjusting reaction time and/or solvent composition. The surface properties as a function of thickness were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM). The influence of PNIPAAm-grafted layer thickness on human serum albumin (HSA) adsorption in phosphate-buffered saline (PBS) (pH 7.4) at different temperature was evaluated using a radiolabeling method. In a lower thickness range (<15 nm), protein adsorption on PNIPAAm-grafted layer shows a thermoresponsive change in a certain extent, but the variation is not remarkable. However, it is interesting to observe that these surfaces exhibit good protein-resistant property. For the surface with a PNIPAAm thickness of 13.4 nm, the HSA adsorption level measured at room temperature was approximately 7 ng/cm2, corresponding to a reduction of 97% compared to the unmodified silicon surface. For thicker PNIPAAm-grafted surface with thickness of 38.1 nm, the adsorption results of three proteins (HSA, fibrinogen, and lysozyme) with different sizes and charges indicate that the PNIPAAm-modified surface exhibits a size-sensitive property of protein adsorption. PMID:20045297

  13. The enhancement of the adhesion of copper layers to Dow Cyclotene 3022 through metal sputtering

    NASA Astrophysics Data System (ADS)

    Yang, D.-Q.; Sacher, E.; Griswold, E. M.; Smith, G.

    2001-08-01

    A study has been made of the effect of relatively high-energy particle (i.e. Ar +, Cu 0, Ti 0) treatment of the Cyclotene surface on the adhesion of deposited metals. XPS has revealed that all the particles damage the surface in the same manner, limiting the ability of the Cyclotene structure to delocalize electrons. In addition, Cu 0 and Ti 0 react with the Cyclotene to form new chemical species, the extent of reaction being proportional to the metal reactivity. AFM and TEM reveal that both metals penetrate to substantial depths below the Cyclotene surface, before diffusing out on annealing. Adhesion tests reveal substantial increases in shear adhesion for both Cu and Ti, but an increase in tensile adhesion for Ti alone. This increase in tensile adhesion is shown to be due to the more extensive chemical reactivity of the Ti.

  14. Device characteristics of amorphous ZnSnLiO thin film transistors with various channel layer thicknesses

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Li, Bin; Zhang, Wenqi; Wu, Huaihao; Zhou, Dongzhan; Yao, Zhigang; Yi, Lixin; Zhang, Xiqing; Wang, Yongsheng

    2016-08-01

    The preparation and characteristics of ZnSnLiO thin film transistors were studied in this work. The ZnSnLiO films, as the channel layers with thickness varied from 20 to 60 nm, were deposited on SiO2/p-type Si substrates by radio frequency magnetron sputtering. The effect of channel layer thickness on the device characteristics of ZnSnLiO TFTs has been investigated to establish optimal channel layer thickness. The transistor with 40-nm-thick ZnSnLiO film shows the best performance with a field-effect mobility of 47 cm2/V s, a threshold voltage of 4.9 V, and an on/off ratio of 7.2 × 106.

  15. Influence of CHx thickness layer on the sensing properties of CHx/PS/Si structure against CO2 gas

    NASA Astrophysics Data System (ADS)

    Zouadi, N.; Belhousse, S.; Bradaî, D.; Cheraga, H.; Ouchabane, M.; Keffous, A.; Sam, S.; Gabouze, N.

    2013-11-01

    In this work, we report a study on the influence of hydrocarbon groups (CHx) thickness layer on sensing properties of CHx/Porous Silicon (PS)/Si structures against CO2 gas. The hydrocarbon groups were deposited by plasma of methane-argon mixture. The properties of these structures are investigated by current-voltage, current-time and capacitance-voltage measurements from where a different behaviour depending on CHx layer thickness has been observed. The results show that current-voltage and impedance-voltage characteristics are modified by the gas reactivity on the CHx/PS surface. As the CHx layer thickness increases, the series resistance and the ideality factor of the structure increase. In addition, the response and recovery times of the sensor decrease with increasing the CHx thickness. Finally, the results point out the effect of CHx coating on the sensitivity of the CHx/PS/Si sensor.

  16. Narrowband impedance matching layer for high efficiency thickness mode ultrasonic transducers.

    PubMed

    Toda, Minoru

    2002-03-01

    A new matching layer design concept has been proposed for narrowband continuous wave (CW) devices. Analysis has shown that the mechanical impedance of a resonant-type transducer in thickness mode CW operation does not equal its acoustic impedance rhoVs but roughly equals rhoVs/Q, where p is density, Vs is acoustic velocity, and Q is the mechanical quality factor. The value of rhoVs/Q is much lower than the acoustic impedance of water for any transducer material, including lead zirconium titanate (PZT), single crystals, or polyvinylidene fluoride (PVDF). With this new approach, the impedance of the matching layer must also be between water and pVs/Q, but there are few such practical low impedance materials. To realize equivalent low impedance structure, a novel double layer design is presented: a relatively low impedance material (such as polyethylene or polyurethane) on the inside and a relatively high impedance material (such as polyester or metal) on the outside. A high power CW transducer structure was designed and fabricated with PVDF-TrFE (polyvinylidene fluoride trifluoroethylene) to operate at 1.4 MHz. The basic quarter wavelength resonator structure is 0.7-mm alumina/0.2-mm piezo-polymer/0.25-mm polyester, and the matching section is 0.2-mm polyurethane and 0.25-mm polyester. A maximum power output of 6 to 9 W/cm2 with conversion efficiency of 30 to 35% was observed. For the transducer without matching section, the observed power was 3 to 4 W/cm2. Mason's model analyses (1) predict that the traditional matching layer is for broadband purposes and reduces output power both for PZT and PVDF-TrFE (2); this new matching scheme can be applied to PZT high power transducer. This high efficiency technique has application in various CW systems, such as Doppler sensors, interferometry, phase-sensitive imaging, or high energy focused beam systems. PMID:12322878

  17. Influence of layer thickness on the structure and the magnetic properties of Co/Pd epitaxial multilayer films

    NASA Astrophysics Data System (ADS)

    Tobari, Kousuke; Ohtake, Mitsuru; Nagano, Katsumasa; Futamoto, Masaaki

    2012-03-01

    Co/Pd epitaxial multilayer films were prepared on Pd(111)fcc underlayers hetero-epitaxially grown on MgO(111)B1 single-crystal substrates at room temperature by ultra-high vacuum RF magnetron sputtering. In-situ reflection high energy electron diffraction shows that the in-plane lattice spacing of Co on Pd layer gradually decreases with increasing the Co layer thickness, whereas that of Pd on Co layer remains unchanged during the Pd layer formation. The CoPd alloy phase formation is observed around the Co/Pd interface. The atomic mixing is enhanced for thinner Co and Pd layers in multilayer structure. With decreasing the Co and the Pd layer thicknesses and increasing the repetition number of Co/Pd multilayer film, stronger perpendicular magnetic anisotropy is observed. The relationships between the film structure and the magnetic properties are discussed.

  18. Thick escaping magnetospheric ion layer in magnetopause reconnection with MMS observations

    NASA Astrophysics Data System (ADS)

    Nagai, T.; Kitamura, N.; Hasegawa, H.; Shinohara, I.; Yokota, S.; Saito, Y.; Nakamura, R.; Giles, B. L.; Pollock, C.; Moore, T. E.; Dorelli, J. C.; Gershman, D. J.; Paterson, W. R.; Avanov, L. A.; Chandler, M. O.; Coffey, V.; Sauvaud, J. A.; Lavraud, B.; Russell, C. T.; Strangeway, R. J.; Oka, M.; Genestreti, K. J.; Burch, J. L.

    2016-06-01

    The structure of asymmetric magnetopause reconnection is explored with multiple point and high-time-resolution ion velocity distribution observations from the Magnetospheric Multiscale mission. On 9 September 2015, reconnection took place at the magnetopause, which separated the magnetosheath and the magnetosphere with a density ratio of 25:2. The magnetic field intensity was rather constant, even higher in the asymptotic magnetosheath. The reconnected field line region had a width of approximately 540 km. In this region, streaming and gyrating ions are discriminated. The large extension of the reconnected field line region toward the magnetosheath can be identified where a thick layer of escaping magnetospheric ions was formed. The scale of the magnetosheath side of the reconnected field line region relative to the scale of its magnetospheric side was 4.5:1.

  19. 1-nm-thick graphene tri-layer as the ultimate copper diffusion barrier

    SciTech Connect

    Nguyen, Ba-Son; Lin, Jen-Fin

    2014-02-24

    We demonstrate the thinnest ever reported Cu diffusion barrier, a 1-nm-thick graphene tri-layer. X-ray diffraction patterns and Raman spectra show that the graphene is thermally stable at up to 750 °C against Cu diffusion. Transmission electron microscopy images show that there was no inter-diffusion in the Cu/graphene/Si structure. Raman analyses indicate that the graphene may have degraded into a nanocrystalline structure at 750 °C. At 800 °C, the perfect carbon structure was damaged, and thus the barrier failed. The results of this study suggest that graphene could be the ultimate Cu interconnect diffusion barrier.

  20. Surface charging of thick porous water ice layers relevant for ion sputtering experiments

    NASA Astrophysics Data System (ADS)

    Galli, A.; Vorburger, A.; Pommerol, A.; Wurz, P.; Jost, B.; Poch, O.; Brouet, Y.; Tulej, M.; Thomas, N.

    2016-07-01

    We use a laboratory facility to study the sputtering properties of centimeter-thick porous water ice subjected to the bombardment of ions and electrons to better understand the formation of exospheres of the icy moons of Jupiter. Our ice samples are as similar as possible to the expected moon surfaces but surface charging of the samples during ion irradiation may distort the experimental results. We therefore monitor the time scales for charging and discharging of the samples when subjected to a beam of ions. These experiments allow us to derive an electric conductivity of deep porous ice layers. The results imply that electron irradiation and sputtering play a non-negligible role for certain plasma conditions at the icy moons of Jupiter. The observed ion sputtering yields from our ice samples are similar to previous experiments where compact ice films were sputtered off a micro-balance.

  1. Million year old ice found under meter thick debris layer in Antarctica

    NASA Astrophysics Data System (ADS)

    Bibby, Theodore; Putkonen, Jaakko; Morgan, Daniel; Balco, Greg; Shuster, David L.

    2016-07-01

    Cosmogenic nuclide measurements associated with buried glacier ice in Ong Valley, in the Transantarctic Mountains, suggest the preservation of ancient ice. There are three glacial tills on the valley floor which have formed from the concentration of regolith contained within sublimating glacier ice. Two tills are less than 1 m thick and underlain by ice. Measurements of cosmogenic 10Be, 26Al, and 21Ne show that (i) the youngest buried ice unit and corresponding till are at least 11-13 ka, (ii) another ice unit and corresponding intermediate-age till are at least 1.1 Ma old under any circumstances and most likely older than 1.78 Ma, and (iii) the oldest till is at least 1.57 Ma and most likely greater than 2.63 Ma. These observations highlight the longevity of ice under thin debris layers and the potential to sample ancient ice for paleoclimate/paleoatmosphere information close to the present land surface.

  2. Development of Very Low Frequency Self-Nulling Probe for Inspection of Thick Layered Aluminum Structures

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Namkung, Min

    1998-01-01

    It is clear from simple skin depth considerations that steady state electromagnetic inspection of thick multi-layered conductors requires low frequency excitation. Conventional pickup sensors, however, lose sensitivity at lower frequencies. Giant magneto resistive materials offer a unique alternative for very low frequency electromagnetic NDE due to their high sensitivity to low frequency fields, small size, ease of use, and low cost. This paper outlines the development and testing of a Very Low Frequency Self-Nulling Probe incorporating a GMR sensor. The initial test results show flaw detectability at depths up to 1 cm in aluminum 2024. Optimization of the probe design based upon finite element modeling and GMR sensor characteristics (including hysteresis, linearity and saturation) is under way.

  3. How oil properties and layer thickness determine the entrainment of spilled surface oil.

    PubMed

    Zeinstra-Helfrich, Marieke; Koops, Wierd; Murk, Albertinka J

    2016-09-15

    Viscosity plays an important role in dispersion of spilled surface oil, so does adding chemical dispersants. For seven different oil grades, entrainment rate and initial droplet size distribution were investigated using a plunging jet apparatus with coupled camera equipment and subsequent image analysis. We found that amount of oil entrained is proportional to layer thickness and largely independent of oil properties: A dispersant dose of 1:200 did not result in a significantly different entrainment rate compared to no dispersants. Oil viscosity had a minor to no influence on entrainment rate, until a certain threshold above which entrainment was impeded. The mean droplet size scales with the modified Weber number as described by Johansen. The obtained results can help improve dispersion algorithms in oil spill fate and transport models, to aid making an informed decision about application of dispersants. PMID:27345705

  4. The Anterior Chamber Depth and Retinal Nerve Fiber Layer Thickness in Children

    PubMed Central

    Lee, Jacky W. Y.; Yau, Gordon S. K.; Woo, Tiffany T. Y.; Yick, Doris W. F.; Tam, Victor T. Y.; Yuen, Can Y. F.

    2014-01-01

    Purpose. To investigate the correlation of anterior chamber depth (ACD) with the peripapillary retinal nerve fiber layer (RNFL) thickness, age, axial length (AL), and spherical equivalent in children. Subjects. Consecutive subjects aged 4 to 18 were recruited. Visually disabling eye conditions were excluded. Only the right eye was included for analysis. The ACD was correlated with RNFL thickness, age, spherical equivalent, and AL for all subjects. Subjects were then divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<−1.0 D), emmetropes (≥−1.0 to ≤+1.0 D), and hyperopes (>+1.0 D). The ACD was compared among the 3 groups before and after age adjustment. Results. In 200 subjects (mean age 7.6 ± 3.3 years), a deeper ACD was correlated with thinner global RNFL (r = −0.2, r2 = 0.06, P = 0.0007), older age (r = 0.4, r2 = 0.1, P < 0.0001), myopic spherical equivalent (r = −0.3, r2 = 0.09, P < 0.0001), and longer AL (r = 0.5, r2 = 0.2, P < 0.0001). The ACD was deepest in myopes (3.5 ± 0.4 mm, n = 67), followed by emmetropes (3.4 ± 0.3, n = 60) and then hyperopes (3.3 ± 0.2, n = 73) (all P < 0.0001). After age adjustment, myopes had a deeper ACD than the other 2 groups (all P < 0.0001). Conclusions. In children, a deeper ACD was associated with thinner RNFL thickness, older age, more myopic spherical equivalent, and longer AL. Myopes had a deeper ACD than emmetropes and hyperopes. PMID:25431789

  5. Validation and Variation of Upper Layer Thickness in South China Sea from Satellite Altimeter Data

    PubMed Central

    Lin, Chun-Yi; Ho, Chung-Ru; Zheng, Zhe-Wen; Kuo, Nan-Jung

    2008-01-01

    Satellite altimeter data from 1993 to 2005 has been used to analyze the seasonal variation and the interannual variability of upper layer thickness (ULT) in the South China Sea (SCS). Base on in-situ measurements, the ULT is defined as the thickness from the sea surface to the depth of 16°C isotherm which is used to validate the result derived from satellite altimeter data. In comparison with altimeter and in-situ derived ULTs yields a correlation coefficient of 0.92 with a slope of 0.95 and an intercept of 6 m. The basin averaged ULT derived from altimeter is 160 m in winter and 171 m in summer which is similar to the in-situ measurements of 159 m in winter and 175 m in summer. Both results also show similar spatial patterns. It suggests that the sea surface height data derived from satellite sensors are usable for study the variation of ULT in the semi-closed SCS. Furthermore, we also use satellite derived ULT to detect the development of eddy. Interannual variability of two meso-scale cyclonic eddies and one anticyclonic eddy are strongly influenced by El Niño events. In most cases, there are highly positive correlations between ULT and sea surface temperature except the periods of El Niño. During the onset of El Niño event, ULT is deeper when sea surface temperature is lower.

  6. Elastic bending modulus of single-layer molybdenum disulfide (MoS2): finite thickness effect.

    PubMed

    Jiang, Jin-Wu; Qi, Zenan; Park, Harold S; Rabczuk, Timon

    2013-11-01

    We derive, from an empirical interaction potential, an analytic formula for the elastic bending modulus of single-layer MoS2 (SLMoS2). By using this approach, we do not need to define or estimate a thickness value for SLMoS2, which is important due to the substantial controversy in defining this value for two-dimensional or ultrathin nanostructures such as graphene and nanotubes. The obtained elastic bending modulus of 9.61 eV in SLMoS2 is significantly higher than the bending modulus of 1.4 eV in graphene, and is found to be within the range of values that are obtained using thin shell theory with experimentally obtained values for the elastic constants of SLMoS2. This increase in bending modulus as compared to monolayer graphene is attributed, through our analytic expression, to the finite thickness of SLMoS2. Specifically, while each monolayer of S atoms contributes 1.75 eV to the bending modulus, which is similar to the 1.4 eV bending modulus of monolayer graphene, the additional pairwise and angular interactions between out of plane Mo and S atoms contribute 5.84 eV to the bending modulus of SLMoS2. PMID:24084656

  7. Use of a Soluble Anode in Electrodeposition of Thick Bismuth Telluride Layers

    NASA Astrophysics Data System (ADS)

    Maas, M.; Diliberto, S.; de Vaulx, C.; Azzouz, K.; Boulanger, C.

    2014-10-01

    Integration of thermoelectric devices within an automotive heat exchanger could enable conversion of lost heat into electrical energy, contributing to improved total output from the engine. For this purpose, synthesis of thick bismuth telluride (Bi2Te3) films is required. Bismuth telluride has been produced by an electrochemical method in nitric acid with a sacrificial bismuth telluride anode as the source of cations. The binary layer grows on the working electrode while the counter-electrode, a Bi2Te3 disk obtained by high frequency melting, is oxidized to BiIII and TeIV. This process leads to auto-regeneration of the solution without modification of its composition. The thickness of films deposited by use of the Bi2Te3 anode was approximately 10 times that without. To demonstrate the utility of a soluble anode in electrochemical deposition, we report characterization of the composition and morphology of the films obtained under different experimental conditions. Perfectly dense and regular Bi2Te3 films (˜400 μm) with low internal stress and uniform composition across the cross-section were prepared. Their thermoelectric properties were assessed.

  8. Analytical Sensor Response Function of Viscosity Sensors Based on Layered Piezoelectric Thickness Shear Resonators

    NASA Astrophysics Data System (ADS)

    Benes, Ewald; Nowotny, Helmut; Braun, Stefan; Radel, Stefan; Gröschl, Martin

    Resonant piezoelectric sensors based on bulk acoustic wave (BAW) thickness shear resonators are promising for the inline measurement of fluid viscosity, e.g., in industrial processes. The sensor response function can be derived from the general rigorous transfer matrix description of one-dimensional layered structures consisting of piezoelectric and non-piezoelectric layers of arbitrary number. This model according to Nowotny et al. provides a complete analytical description of the electrical and mechanical behaviour of such structures with two electrodes and arbitrary acoustic termination impedances (Rig-1d-Model). We apply this model to derive the sensor response functions and the mechanical displacement curves of the following configurations appropriate for viscosity sensors: An AT cut quartz crystal plate in contact with vacuum at the backside plane and with the liquid under investigation at the front side plane (QL). An AT cut quartz crystal in contact with the liquid under investigation at both sides (LQL). It is shown that in the QL case the originally only heuristically introduced and well established sensor response function according to Kanasawa can be derived from the Rig-1d-Model by introducing minor approximations. Experimental results are presented for the LQL configuration using an N1000 viscosity reference oil as test fluid.

  9. Aqueous dispersions of few-layer-thick chemically modified magnesium diboride nanosheets by ultrasonication assisted exfoliation.

    PubMed

    Das, Saroj Kumar; Bedar, Amita; Kannan, Aadithya; Jasuja, Kabeer

    2015-01-01

    The discovery of graphene has led to a rising interest in seeking quasi two-dimensional allotropes of several elements and inorganic compounds. Boron, carbon's neighbour in the periodic table, presents a curious case in its ability to be structured as graphene. Although it cannot independently constitute a honeycomb planar structure, it forms a graphenic arrangement in association with electron-donor elements. This is exemplified in magnesium diboride (MgB2): an inorganic layered compound comprising boron honeycomb planes alternated by Mg atoms. Till date, MgB2 has been primarily researched for its superconducting properties; it hasn't been explored for the possibility of its exfoliation. Here we show that ultrasonication of MgB2 in water results in its exfoliation to yield few-layer-thick Mg-deficient hydroxyl-functionalized nanosheets. The hydroxyl groups enable an electrostatically stabilized aqueous dispersion and create a heterogeneity leading to an excitation wavelength dependent photoluminescence. These chemically modified MgB2 nanosheets exhibit an extremely small absorption coefficient of 2.9 ml mg(-1) cm(-1) compared to graphene and its analogs. This ability to exfoliate MgB2 to yield nanosheets with a chemically modified lattice and properties distinct from the parent material presents a fundamentally new perspective to the science of MgB2 and forms a first foundational step towards exfoliating metal borides. PMID:26041686

  10. Distribution and landscape controls of organic layer thickness and carbon within the Alaskan Yukon River Basin

    USGS Publications Warehouse

    Pastick, Neal J.; Rigge, Matthew B.; Wylie, Bruce K.; Jorgenson, M. Torre; Rose, Joshua R.; Johnson, Kristofer D.; Ji, Lei

    2014-01-01

    Understanding of the organic layer thickness (OLT) and organic layer carbon (OLC) stocks in subarctic ecosystems is critical due to their importance in the global carbon cycle. Moreover, post-fire OLT provides an indicator of long-term successional trajectories and permafrost susceptibility to thaw. To these ends, we 1) mapped OLT and associated uncertainty at 30 m resolution in the Yukon River Basin (YRB), Alaska, employing decision tree models linking remotely sensed imagery with field and ancillary data, 2) converted OLT to OLC using a non-linear regression, 3) evaluate landscape controls on OLT and OLC, and 4) quantified the post-fire recovery of OLT and OLC. Areas of shallow (2 = 0.68; OLC: R2 = 0.66), where an average of 16 cm OLT and 5.3 kg/m2 OLC were consumed by fires. Strong predictors of OLT included climate, topography, near-surface permafrost distributions, soil wetness, and spectral information. Our modeling approach enabled us to produce regional maps of OLT and OLC, which will be useful in understanding risks and feedbacks associated with fires and climate feedbacks.

  11. Aqueous dispersions of few-layer-thick chemically modified magnesium diboride nanosheets by ultrasonication assisted exfoliation

    PubMed Central

    Das, Saroj Kumar; Bedar, Amita; Kannan, Aadithya; Jasuja, Kabeer

    2015-01-01

    The discovery of graphene has led to a rising interest in seeking quasi two-dimensional allotropes of several elements and inorganic compounds. Boron, carbon’s neighbour in the periodic table, presents a curious case in its ability to be structured as graphene. Although it cannot independently constitute a honeycomb planar structure, it forms a graphenic arrangement in association with electron-donor elements. This is exemplified in magnesium diboride (MgB2): an inorganic layered compound comprising boron honeycomb planes alternated by Mg atoms. Till date, MgB2 has been primarily researched for its superconducting properties; it hasn’t been explored for the possibility of its exfoliation. Here we show that ultrasonication of MgB2 in water results in its exfoliation to yield few-layer-thick Mg-deficient hydroxyl-functionalized nanosheets. The hydroxyl groups enable an electrostatically stabilized aqueous dispersion and create a heterogeneity leading to an excitation wavelength dependent photoluminescence. These chemically modified MgB2 nanosheets exhibit an extremely small absorption coefficient of 2.9 ml mg−1 cm−1 compared to graphene and its analogs. This ability to exfoliate MgB2 to yield nanosheets with a chemically modified lattice and properties distinct from the parent material presents a fundamentally new perspective to the science of MgB2 and forms a first foundational step towards exfoliating metal borides. PMID:26041686

  12. Constraining the Thickness of the Crystal Mush in Layered Mafic Intrusions

    NASA Astrophysics Data System (ADS)

    Holness, M. B.; Tegner, C.; Nielsen, T. F.

    2009-12-01

    When basaltic magma stalls in the crust, cooling leads to growth of a marginal mushy layer. The thickness of this crystal mush can be constrained using the step-changes in textural maturity (quantified by the median augite(cpx)-plag-plag dihedral angle, Θcpp) caused by the change in fractional latent heat accompanying the arrival of a new liquidus phase. At the instant of its saturation in the bulk magma, the top of the mush is marked by the first appearance of the new primocryst phase. At this moment, the high porosity upper zone of the mush comprises poorly consolidated material, with no cpx-plag-plag junctions: at deeper levels porosity decreases by primocryst overgrowth, growth of interstitial augite, and compaction. In the context of dihedral angle populations, the mush zone can be divided into 3: the upper zone, where melt is adjacent to all plag-plag junctions; the middle zone where augite fills some of the pore corners; and the lower zone where augite fills all pore corners. For our purposes, the base of this lower zone corresponds to the point at which diffusive change of grain boundary orientations has effectively ceased. The change in fractional latent heat accompanying the addition to the liquidus assemblage will be fully recorded within the upper zone since all cpx-plag-plag junctions are created after the change and its consequent decrease in the contribution of sensible heat to the total enthalpy loss: Θcpp will be high. The middle zone will record a mixture of the new and old thermal regime: junctions which were melt-filled at the moment of arrival of the new phase will have less opportunity to increase the cpx-plag-plag angle, while those which were already filled by augite will have higher angles. Θcpp will therefore range from the new higher value at the top of middle zone, to some lower value at the base. Cumulates in the lower zone had no melt-filled junctions: Θcpp will increase from a low value corresponding to the previous value of

  13. Thick bottom nepheloid layers in the western Mediterranean generated by deep dense shelf water cascading

    NASA Astrophysics Data System (ADS)

    Puig, Pere; Madron, Xavier Durrieu de; Salat, Jordi; Schroeder, Katrin; Martín, Jacobo; Karageorgis, Aristomenis P.; Palanques, Albert; Roullier, François; Lopez-Jurado, José Luis; Emelianov, Mikhail; Moutin, Thierry; Houpert, Loïc

    2013-04-01

    The analysis of a compilation of deep CTD casts conducted in the western Mediterranean from 1998 to 2011 has documented the role that dense water formation, and particularly deep dense shelf water cascading off the Gulf of Lions, plays in transporting suspended particulate matter from the coastal regions down to the basin. Deep CTD casts reveal that after the 1999 and 2005-2006 deep cascading events the Western Mediterranean Deep Water (WMDW) was characterized by the presence of a thick bottom nepheloid layer (BNL) that corresponded in thickness with a thermohaline anomaly generated by the mixture of dense waters formed by deep convection in the open sea and by deep cascading. This BNL can be hundreds of meters thick and in the central part of the basin usually exhibits suspended sediment concentrations of <0.1 mg/l above background levels, reaching higher concentrations close to the continental rise, with near-bottom peaks >1 mg/l. After winter 1999 the BNL spread from the Gulf of Lions and the Catalan margin over the northwestern Mediterranean basin, reaching west of the Balearic Islands and the Ligurian Sea, while after winters 2005-2006 the BNL covered the entire western Mediterranean basin. Thickness and concentration of the BNL tend to diminish with time but this trend is highly dependent on the volume of dense water generated, both by convection and cascading. After winter 1999 the BNL signal vanished in one year, but after winters 2005-2006 it lasted for longer and the turbidity signal can still be distinguished at present (2011). Particle size distribution in the BNL reveals the presence of large aggregates up to 1 mm in size formed by a mixture of single particles with the same bimodal grain size distribution as the surface sediments found in the northwestern Mediterranean slope and basin. Results presented in this paper highlight the fact that the WMDW can be periodically affected by the arrival of new dense waters loaded with suspended particles mainly

  14. The shape dependence of core shell and hollow titania nanoparticles on coating thickness during layer-by-layer and sol gel synthesis

    NASA Astrophysics Data System (ADS)

    Nelson, Kimberly; Deng, Yulin

    2006-07-01

    Titania core-shell and hollow nanoparticles with different aspect ratios were synthesized using layer-by-layer assembly and sol-gel nanocoating methods with cellulose nanowhiskers as the template. During growth of the coating layer, the shape of the nanoparticles did not maintain the shape of the high aspect ratio template, as previously assumed. The shape of the coated particles is a function of the coating thickness. It is suggested that the overall particle shape and aspect ratio of the nanoparticles are tunable by choosing an appropriate template and coating thickness in layer-by-layer or sol-gel templating synthesis. The nanorods and hollow titania particles synthesized by these methods were characterized by transmission electron microscopy, scanning electron microscopy and x-ray diffraction.

  15. On the increasing of adhesive strength of nanotube layers on beta titanium alloys for medical applications

    NASA Astrophysics Data System (ADS)

    Fojt, Jaroslav; Filip, Vladimir; Joska, Ludek

    2015-11-01

    The nanostructuring of titanium and its alloys surfaces is used inter alia for increasing the medical implants osseointegration. Many papers about this topic were published. However, in most cases there were no informations about nanostructures adhesion to the surface, which is crucial from the application point of view. The aim of this study was to prepare nanostructures on titanium beta alloy and optimized its adhesion to the alloy surface. Nanotubes were formed by anodic polarization in electrolyte containing fluoride ions. The composition of the nanotubes was described by X-ray photoelectron spectroscopy. Nanostructures adhesion was tested by pull-of method. The nanotubes on the Ti-36Nb-6Ta beta alloy surface were prepared by anodization. The nanostructures properties were modified by electrochemical process parameters. The adhesion of the nanotubes prepared in this work was satisfactory for implantological applications.

  16. Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography

    PubMed Central

    Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K. W.; Yoshimura, Nagahisa

    2016-01-01

    Purpose To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. Methods The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Results Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. Conclusions The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction. PMID:26814541

  17. Longitudinal Changes in Retinal Nerve Fiber Layer Thickness after Intravitreal Anti-vascular Endothelial Growth Factor Therapy

    PubMed Central

    Jo, Young-Joon; Kim, Woo-Jin; Shin, Il-Hwan

    2016-01-01

    Purpose To determine the effects of intravitreal anti-vascular endothelial growth factor (VEGF) on thickness of the retinal nerve fiber layer (RNFL) in patients with age-related macular degeneration. Methods Twenty eyes of 20 patients diagnosed with age-related macular degeneration who underwent intravitreal anti-VEGF injection were studied. Postinjection RNFL thickness was measured using optical coherence tomography. Average thickness, four-quadrant RNFL thicknesses, and intraocular pressure (IOP) in affected eyes were measured before and 6 and 12 months after anti-VEGF injection for comparison. RNFL thickness and IOP in affected and normal fellow eyes were also compared. Given that macular lesions can affect RNFL thickness, the changes in thickness were evaluated by dividing the 12 clock-hour RNFL into the pathologic areas adjacent to the lesion and the non-pathologic area. Results The mean clock-hour segment in the pathologic area was 4.8 hours. A significantly thicker RNFL was exhibited in temporal quadrants and pathologic areas (p = 0.043 and 0.048, respectively) in affected eyes before injection compared to the baseline RNFL thickness in normal eyes. No significant differences were found in RNFL thickness or IOP between affected and normal eyes after injection. The changes over time in the temporal and pathologic areas were statistically significant at 6 and 12 months after injection compared to baseline data (p < 0.05). No significant differences were displayed in RNFL thickness in the other three quadrants or in non-pathologic areas in either affected or normal eyes. Sequential changes in RNFL thickness in affected eyes were not significant. Conclusions Repeat intravitreal anti-VEGF treatment did not have a significant effect on RNFL thickness. RNFL thickness significantly decreased with time in the pathologic areas and in the temporal segment adjacent to exudative macular lesions. The reduction in RNFL thickness was most likely associated with changes in

  18. A vapor-phase deposited polymer film to improve the adhesion of electroless-deposited copper layer onto various kinds of substrates.

    PubMed

    You, Jae Bem; Kim, Shin Young; Park, Yong Jin; Ko, Young Gwan; Im, Sung Gap

    2014-01-28

    The adhesion of electrodeposited metal film to polymeric circuit board substrate is one of the key elements to successful miniaturization of electronic devices. However, as the size of the circuit pattern continuously decreases, a novel method is urgently required to increase the adhesion of the metal film on the substrate, especially on the smooth surface, which is critical to decrease the minimum feature size of the metal pattern. In this research, we developed an adhesion promoter layer by depositing metal chelating poly(4-vinylpyridine) (P4VP) film onto various organic and inorganic substrates via initiated chemical vapor deposition process (iCVD) to enhance the adhesion between the electroless deposited copper (Cu) layer and the substrate. The highest peel strength obtained between the electroless deposited Cu layer and P4VP coated substrate was 1.22 kgf/cm. Many advantageous characteristics of the adhesion promoter layer, including extreme thinness, the improved adhesion strength, conformal coverage, scalability of the deposition process, and short process time, will prompt the applicability of this adhesion promoter layer to industrial scale production. PMID:24393010

  19. Evolution of damping in ferromagnetic/nonmagnetic thin film bilayers as a function of nonmagnetic layer thickness

    NASA Astrophysics Data System (ADS)

    Azzawi, S.; Ganguly, A.; Tokaç, M.; Rowan-Robinson, R. M.; Sinha, J.; Hindmarch, A. T.; Barman, A.; Atkinson, D.

    2016-02-01

    The evolution of damping in Co/Pt, Co/Au, and Ni81Fe19 /Pt bilayers was studied with increasing nonmagnetic (NM) heavy-metal layer thicknesses in the range 0.2 nm ≤tNM≤10 nm , where tNM is the NM layer thickness. Magnetization precession was measured in the time domain using time-resolved magneto-optical Kerr effect magnetometry. Fitting of the data with a damped sinusoidal function was undertaken in order to extract the phenomenological Gilbert damping coefficient α . For Pt-capped Co and Ni81Fe19 layers a large and complex dependence of α on the Pt layer thickness was observed, while for Au capping no significant dependence was observed. It is suggested that this difference is related to the different localized spin-orbit interaction related to intermixing and to d -d hybridization of Pt and Au at the interface with Co or Ni81Fe19 . Also it was shown that damping is affected by the crystal structure differences in FM thin films and at the interface, which can modify the spin-diffusion length and the effective spin-mixing conductance. In addition to the intrinsic damping an extrinsic contribution plays an important role in the enhancement of damping when the Pt capping layer is discontinuous. The dependence of damping on the nonmagnetic layer thickness is complex but shows qualitative agreement with recent theoretical predictions.

  20. Investigation of Thickness Dependence of Metal Layer in Al/Mo/4H-SiC Schottky Barrier Diodes.

    PubMed

    Lee, Seula; Lee, Jinseon; Kang, Tai-Young; Kyoung, Sinsu; Jung, Eun Sik; Kim, Kyung Hwan

    2015-11-01

    In this paper, we present the preparation and characterization of Schottky barrier diodes based on silicon carbide with various Schottky metal layer thickness values. In this structure, molybdenum and aluminum were employed as the Schottky barrier metal and top electrode, respectively. Schottky metal layers were deposited with thicknesses ranging from 1000 to 3000 Å, and top electrodes were deposited with thickness as much as 3000 Å. The deposition of both metal layers was performed using the facing target sputtering (FTS) method, and the fabricated samples were annealed with the tubular furnace at 300 degrees C under argon ambient for 10 min. The Schottky barrier height, series resistance, and ideality factor was calculated from the forward I-V characteristic curve using the methods proposed by Cheung and Cheung, and by Norde. For as-deposited Schottky diodes, we observed an increase of the threshold voltage (V(T)) as the thickness of the Schottky metal layer increased. After the annealing, the Schottky barrier heights (SBHs) of the diodes, including Schottky metal layers of over 2000 Å, increased. In the case of the Schottky metal layer deposited to 1000 Å, the barrier heights decreased due to the annealing process. This may have been caused by the interfacial penetration phenomenon through the Schottky metal layer. For variations of V(T), the SBH changed with a similar tendency. The ideality factor and series resistance showed no significant changes before or after annealing. This indicates that this annealing condition is appropriate for Mo SiC structures. Our results confirm that it is possible to control V(T) by adjusting the thickness of the Schottky metal layer. PMID:26726688

  1. Diurnal Variations in Intraocular Pressure, Central Corneal Thickness, and Macular and Retinal Nerve Fiber Layer Thickness in Diabetics and Normal Individuals

    PubMed Central

    Sharifipour, Farideh; Farrahi, Fereidoun; Moghaddasi, Alireza; Idani, Aida; Yaseri, Mehdi

    2016-01-01

    Purpose: To evaluate diurnal variations in intraocular pressure (IOP), central corneal thickness (CCT), and macular and retinal nerve fiber layer (RNFL) thickness in diabetic patients and normal individuals. Methods: This study included 11 diabetic patients with macular edema and 11 healthy individuals. IOP, CCT, and macular and RNFL thickness were measured every 3 hours on a single day between 9 AM and 6 PM. Diurnal variations in IOP, CCT, total macular volume (TMV), central macular thickness (CMT), average macular thickness (AMT), and RNFL thickness were measured. Results: None of the parameters showed a significant absolute or relative change over the course of the day. However, the following non-significant changes were observed. In the control group, all parameters demonstrated the highest values at 9 AM. The lowest IOP, TMV and AMT occurred at 12 PM; lowest CCT and RNFL at 6 PM; and the lowest CMT at 3 PM. Diabetic subjects had the highest values of RNFL, CMT and TMV at 9 AM, and that for IOP, CCT and AMT at 6 PM. The lowest RNFL and CMT values occurred at 6 PM; lowest IOP at 12 PM; and the lowest CCT, TMV and AMT were observed at 3 PM. In the diabetic group, TMV, CMT, AMT and CCT were significantly higher and RNFL was significantly lower than the control group at all time points (all P- values < 0.05). Conclusion: While there were slight decreases in IOP, RNFL thickness and CMT during the day, these changes were not significant between 9 AM and 6 PM and probably do not affect the interpretation of measurements. PMID:27195084

  2. Temperature and layer thickness dependent in situ investigations on epindolidione organic thin-film transistors

    PubMed Central

    Lassnig, R.; Striedinger, B.; Jones, A.O.F.; Scherwitzl, B.; Fian, A.; Głowacl, E.D.; Stadlober, B.; Winkler, A.

    2016-01-01

    We report on in situ performance evaluations as a function of layer thickness and substrate temperature for bottom-gate, bottom-gold contact epindolidione organic thin-film transistors on various gate dielectrics. Experiments were carried out under ultra-high vacuum conditions, enabling quasi-simultaneous electrical and surface analysis. Auger electron spectroscopy and thermal desorption spectroscopy (TDS) were applied to characterize the quality of the substrate surface and the thermal stability of the organic films. Ex situ atomic force microscopy (AFM) was used to gain additional information on the layer formation and surface morphology of the hydrogen-bonded organic pigment. The examined gate dielectrics included SiO2, in its untreated and sputtered forms, as well as the spin-coated organic capping layers poly(vinyl-cinnamate) (PVCi) and poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE, from the class of polynorbornenes). TDS and AFM revealed Volmer-Weber island growth dominated film formation with no evidence of a subjacent wetting layer. This growth mode is responsible for the comparably high coverage required for transistor behavior at 90–95% of a monolayer composed of standing molecules. Surface sputtering and an increased sample temperature during epindolidione deposition augmented the surface diffusion of adsorbing molecules and therefore led to a lower number of better-ordered islands. Consequently, while the onset of charge transport was delayed, higher saturation mobility was obtained. The highest, bottom-contact configuration, mobilities of approximately 2.5 × 10−3cm2/Vs were found for high coverages (50 nm) on sputtered samples. The coverage dependence of the mobility showed very different characteristics for the different gate dielectrics, while the change of the threshold voltage with coverage was approximately the same for all systems. An apparent decrease of the mobility with increasing coverage on the

  3. Change of interface dipole energy with interfacial layer thickness and O2 plasma treatment in metal/organic interface

    NASA Astrophysics Data System (ADS)

    Kim, Soo Young; Hong, Kihyon; Lee, Jong-Lam

    2007-04-01

    The authors determined the interface dipole energies between interfacial layers with different thicknesses coated on indium tin oxides (ITOs) and 4,4'-bis[N-(1-naphtyl)-N-phenyl-amino]biphenyl using ultraviolet and synchrotron radiation photoemission spectroscopy. The interface dipole energy increased as a function of interfacial layer thickness up to 4nm. After O2 plasma treatment on thick-metal (>4nm) coated ITO, the work function and interface dipole energy increased. In thin-metal (<2nm) coated ITO, no change in the interface dipole energy was found though the work function increased. Thus, the O2 plasma treated thin (<2nm) interfacial layer reduced the hole injection barrier.

  4. Potential vorticity and layer thickness variations in the flow around Jupiter's Great Red Spot and White Oval BC

    NASA Technical Reports Server (NTRS)

    Dowling, Timothy E.; Ingersoll, Andrew P.

    1988-01-01

    Using Voyager images, layer thickness variations in the flow around Jupiter's Great Red Spot (GRS) and White Oval BC were investigated by treating potential vorticity as a conserved tracer. Fluid trajectories around the GRS and the White Oval BC were calculated assuming the flow to be frictionless, adiabatic, hydrostatic, and steady in the reference frame of the vortex. The data obtained constitute a useful diagnostic which will help to differentiate between models of Jovian vortices. Implications of the observations were studied in the context of a one-layer quasi-geostrophic model in which a thin upper weather layer, which contains the vortex, is supported hydrostatically by a much deeper lower layer.

  5. Potential vorticity and layer thickness variations in the flow around Jupiter's Great Red SPOT and White Oval BC

    NASA Astrophysics Data System (ADS)

    Dowling, T. E.; Ingersoll, A. P.

    1988-04-01

    Using Voyager images, layer thickness variations in the flow around Jupiter's Great Red Spot (GRS) and White Oval BC were investigated by treating potential vorticity as a conserved tracer. Fluid trajectories around the GRS and the White Oval BC were calculated assuming the flow to be frictionless, adiabatic, hydrostatic, and steady in the reference frame of the vortex. The data obtained constitute a useful diagnostic which will help to differentiate between models of Jovian vortices. Implications of the observations were studied in the context of a one-layer quasi-geostrophic model in which a thin upper weather layer, which contains the vortex, is supported hydrostatically by a much deeper lower layer.

  6. Analyses of layer-thickness effects in bilayered dental ceramics subjected to thermal stresses and ring-on-ring tests

    SciTech Connect

    Hsueh, Chun-Hway; Thompson, G. A.; Jadaan, Osama M.; Wereszczak, Andrew A; Becher, Paul F

    2008-01-01

    Objectives. The purpose of this study was to analyze the stress distribution through the thickness of bilayered dental ceramics subjected to both thermal stresses and ring-on-ring tests and to systematically examine how the individual layer thickness influences this stress distribution and the failure origin. Methods. Ring-on-ring tests were performed on In-Ceram Alumina/Vitadur Alpha porcelain bilayered disks with porcelain in the tensile side, and In-Ceram Alumina to porcelain layer thickness ratios of 1:2, 1:1, and 2:1 were used to characterize the failure origins as either surface or interface. Based on the thermomechanical properties and thickness of each layer, the cooling temperature from glass transition temperature, and the ring-on-ring loading configuration, the stress distribution through the thickness of the bilayer was calculated using closed-form solutions. Finite element analyses were also performed to verify the analytical results. Results. The calculated stress distributions showed that the location of maximum tension during testing shifted from the porcelain surface to the In-Ceram Alumina/porcelain interface when the relative layer thickness ratio changed from 1:2 to 1:1 and to 2:1. This trend is in agreement with the experimental observations of the failure origins. Significance. For bilayered dental ceramics subjected to ring-on-ring tests, the location of maximum tension can shift from the surface to the interface depending upon the layer thickness ratio. The closed-form solutions for bilayers subjected to both thermal stresses and ring-on-ring tests are explicitly formulated which allow the biaxial strength of the bilayer to be evaluated.

  7. Determining the Effective Density and Stabilizer Layer Thickness of Sterically Stabilized Nanoparticles

    PubMed Central

    2016-01-01

    A series of model sterically stabilized diblock copolymer nanoparticles has been designed to aid the development of analytical protocols in order to determine two key parameters: the effective particle density and the steric stabilizer layer thickness. The former parameter is essential for high resolution particle size analysis based on analytical (ultra)centrifugation techniques (e.g., disk centrifuge photosedimentometry, DCP), whereas the latter parameter is of fundamental importance in determining the effectiveness of steric stabilization as a colloid stability mechanism. The diblock copolymer nanoparticles were prepared via polymerization-induced self-assembly (PISA) using RAFT aqueous emulsion polymerization: this approach affords relatively narrow particle size distributions and enables the mean particle diameter and the stabilizer layer thickness to be adjusted independently via systematic variation of the mean degree of polymerization of the hydrophobic and hydrophilic blocks, respectively. The hydrophobic core-forming block was poly(2,2,2-trifluoroethyl methacrylate) [PTFEMA], which was selected for its relatively high density. The hydrophilic stabilizer block was poly(glycerol monomethacrylate) [PGMA], which is a well-known non-ionic polymer that remains water-soluble over a wide range of temperatures. Four series of PGMAx–PTFEMAy nanoparticles were prepared (x = 28, 43, 63, and 98, y = 100–1400) and characterized via transmission electron microscopy (TEM), dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS). It was found that the degree of polymerization of both the PGMA stabilizer and core-forming PTFEMA had a strong influence on the mean particle diameter, which ranged from 20 to 250 nm. Furthermore, SAXS was used to determine radii of gyration of 1.46 to 2.69 nm for the solvated PGMA stabilizer blocks. Thus, the mean effective density of these sterically stabilized particles was calculated and determined to lie between 1.19 g

  8. Urban Geocryology: Mapping Urban-Rural Contrasts in Active-Layer Thickness, Barrow Penninsula, Northern Alaska

    NASA Astrophysics Data System (ADS)

    Klene, A. E.; Nelson, F. E.

    2014-12-01

    As development proceeds in the high latitudes, information about interactions between urban influences and the thickness of the active layer above permafrost becomes vital, particularly given the possibility of increasing temperatures accompanying climate change. Permafrost characteristics are often mapped at small geographical scales (i.e., over large areas), at low resolution, and without extensive field validation. Although maps of active-layer thickness (ALT) have been created for areas of relatively undisturbed terrain, this has rarely been done within urbanized areas, even though ALT is a critical factor in the design of roads, buildings, pipelines, and other elements of infrastructure. The need for detailed maps of ALT is emphasized in work on potential hazards in permafrost regions associated with global warming scenarios. Northern Alaska is a region considered to be at moderate to high risk for thaw-induced damage under climatic warming. The Native Village of Barrow (71°17'44"N; 156°45' 59"W), the economic, transportation, and administrative hub of the North Slope Borough, is the northernmost community in the USA, and the largest native settlement in the circum-Arctic. A winter urban heat island in Barrow, earlier snowmelt in the village, and dust deposition downwind of gravel pads and roads are all urban effects that could increase ALT. A recent empirical study documented a 17 to 41 cm difference in ALT between locations in the village of Barrow and surrounding undeveloped tundra, even in similar land-cover classes. We mapped ALT in the Barrow Peninsula, with particular attention to contrasts between the urbanized village and relatively undisturbed tundra in the nearby Barrow Environmental Observatory. The modified Berggren solution, an advanced analytic solution to the general Stefan problem of calculating frost and thaw depth, was used in a geographic context to map ALT over the 150 km² area investigated in the Barrow Urban Heat Island Study. The

  9. Optical reflectivity and Raman scattering in few-layer-thick graphene highly doped by K and Rb.

    PubMed

    Jung, Naeyoung; Kim, Bumjung; Crowther, Andrew C; Kim, Namdong; Nuckolls, Colin; Brus, Louis

    2011-07-26

    We report the optical reflectivity and Raman scattering of few layer (L) graphene exposed to K and Rb vapors. Samples many tens of layers thick show the reflectivity and Raman spectra of the stage 1 bulk alkali intercalation compounds (GICs) KC(8) and RbC(8). However, these bulk optical and Raman properties only begin to appear in samples more than about 15 graphene layers thick. The 1 L to 4 L alkali exposed graphene Raman spectra are profoundly different than the Breit-Wigner-Fano (BWF) spectra of the bulk stage 1 compounds. Samples less than 10 layers thick show Drude-like plasma edge reflectivity dip in the visible; alkali exposed few layer graphenes are significantly more transparent than intrinsic graphene. Simulations show the in-plane free electron density is lower than in the bulk stage 1 GICs. In few layer graphenes, alkalis both intercalate between layers and adsorb on the graphene surfaces. Charge transfer electrically dopes the graphene sheets to densities near and above 10(+14) electrons/cm(2). New intrinsic Raman modes at 1128 and 1264 cm(-1) are activated by in-plane graphene zone folding caused by strongly interacting, locally crystalline alkali adlayers. The K Raman spectra are independent of thickness for L = 1-4, indicating that charge transfer from adsorbed and intercalated K layers are similar. The Raman G mode is downshifted and significantly broadened from intrinsic graphene. In contrast, the Rb spectra vary strongly with L and show increased doping by intercalated alkali as L increases. Rb adlayers appear to be disordered liquids, while intercalated layers are locally crystalline solids. A significant intramolecular G mode electronic resonance Raman enhancement is observed in K exposed graphene, as compared with intrinsic graphene. PMID:21682332

  10. Effect of CeO{sub 2} buffer layer thickness on the structures and properties of YBCO coated conductors.

    SciTech Connect

    Li, M.; Zhao, X.; Ma, B.; Dorris, S. E.; Balachandran, U.; Maroni, V. A.; Wuhan Univ.

    2007-01-01

    Biaxially textured YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films were grown on inclined-substrate-deposited (ISD) MgO-textured metal substrates by pulsed laser deposition. CeO{sub 2} was deposited as a buffer layer prior to YBCO growth. CeO{sub 2} layers of different thickness were prepared to evaluate the thickness dependence of the YBCO films. The biaxial alignment features of the films were examined by X-ray diffraction 2{theta}-scans, pole-figure, {phi}-scans and rocking curves of {Omega} angles. The significant influence of the CeO{sub 2} thickness on the structure and properties of the YBCO films were demonstrated and the optimal thickness was found to be about 10 nm. High values of T{sub c} = 91 K and J{sub c} = 5.5 x 10{sup 5} A/cm{sup 2} were obtained on YBCO films with optimal CeO{sub 2} thickness at 77 K in zero field. The possible mechanisms responsible for the dependence of the structure and the properties of the YBCO films on the thickness of the CeO{sub 2} buffer layers are discussed.

  11. Evaluation of layer thickness in human teeth using higher-order-mode leaky Lamb wave interdigital transducers

    SciTech Connect

    Toda, Shinji; Fujita, Takeshi; Arakawa, Hirohisa; Toda, Kohji

    2005-03-01

    An ultrasonic nondestructive evaluation technique of the layer thickness in human teeth is proposed using a leaky Lamb wave device with two arch-shaped interdigital transducers, operating at a plate/water interface. The use of a higher-order-mode leaky Lamb wave with a phase velocity higher than the longitudinal wave velocity in the human tooth is essential to detect reflected ultrasound beams from the tooth section The layer thickness of dentin, estimated from the measured time interval between two reflected echoes, is in good agreement with the optically measured data.

  12. The Bending Strength, Internal Bonding and Thickness Swelling of a Five Layer Sandwiched Bamboo Particleboard

    NASA Astrophysics Data System (ADS)

    Jamaludin, M. A.; Bahari, S. A.; Nordin, K.; Soh, T. F. T.

    2010-03-01

    The demand for wood based material is increasing but the supply is decreasing. Therefore the price of these raw materials has increased. Bamboo provides an economically feasible alternative raw material for the wood based industry. Its properties are comparable to wood. It is also compatible with the existing processing technology. Bamboo is in abundance, easy to propagate and of short maturation period. Bamboo provides a cheaper alternative resource for the wood based industry. The development of new structural components from bamboo will widen its area of application from handicrafts to furniture and building components. In this study, five layer sandwiched bamboo particleboard were manufactured. The sandwiched Bamboo PB consists of a bamboo PB core, oil palm middle veneers and thin meranti surface veneers. The physical and mechanical properties of the bamboo sandwiched particleboards were tested in accordance to the BS-EN 317:1993 [1] and BS-EN 310:1993 [2], respectively. All the samples passed the standards. The modulus of elasticity was about 352% higher than the value specified in the BS standard, BS-EN 312-4:1996 [3]. The Internal bonding was about 23% higher than the general requirements specified in the standard. On the other hand, the thickness swelling was about 6% lower than the standard. No glue line failure was observed in the strength tests. Critical failures in the IB tests were observed in the particleboards. Tension failures were observed in the surface veneers in the bending tests. The five layer sandwiched bamboo particleboard can be used for light weight construction such as furniture, and wall and door panels in buildings.

  13. Adsorption of plasma proteins and fibronectin on poly(hydroxylethyl methacrylate) brushes of different thickness and their relationship with adhesion and migration of vascular smooth muscle cells

    PubMed Central

    Deng, Jun; Ren, Tanchen; Zhu, Jiyu; Mao, Zhengwei; Gao, Changyou

    2014-01-01

    The surface-grafted poly(hydroxylethyl methacrylate) (PHEMA) molecules were demonstrated to show a brush state regardless of their molecular length (molecular weight). Adsorption of proteins from 10% fetal bovine serum (FBS), fibronectin (Fn) and bovine serum albumin (BSA) was quantified by ellipsometry, revealing that the amounts of FBS and Fn decreased monotonously along with the increase of PHEMA thickness, whereas not detectable for BSA when the PHEMA thickness was larger than 6 nm. Radio immunoassay found that the adsorption of Fn from 10% FBS had no significant difference regardless of the PHEMA thickness. However, ELISA results showed that the Arg-Gly-Asp (RGD) activity of adsorbed Fn decreased with the increase of PHEMA thickness. By comparison of cellular behaviors of vascular smooth muscle cells (VSMCs) being cultured in vitro in the normal serum-containing medium and the Fn-depleted serum-containing medium, the significant role of Fn on modulating the adhesion and migration of VSMCs was verified. Taking account all the results, the Fn adsorption model and its role on linking the biomaterials surface to the VSMCs behaviors are proposed. PMID:26814446

  14. A large-deformation thin plate theory with application to one-atom-thick layers

    NASA Astrophysics Data System (ADS)

    Delfani, M. R.; Shodja, H. M.

    2016-02-01

    Nowadays, two-dimensional materials due to their vast engineering and biomedical applications have been the focus of many researches. The present paper proposes a large-deformation theory for thin plates with application to one-atom-thick layers (OATLs). The deformation is formulated exactly in the mathematical framework of Lagrangian description. In particular, an exact finite strain analysis is given - in addition to the usual strain tensor associated to the middle surface, the second and third fundamental forms of the middle surface of the deformed thin plate are also maintained in the analysis. Exact closed-form solutions for a uniaxially curved thin plate due to pure bending in one case and due to a combination of vertical and horizontal loading in another are obtained. As a special case of the latter problem, the exact solution for the plane-strain bulge test of thin plates is derived. Subsequently, the approximation of Vlassak and Nix [Vlassak, J.J., Nix, W.D., 1992. J. Mater. Res., 7(12), 3242-3249] for the load-deflection equation is recovered. The given numerical results are devoted to graphene as the most well-known OATL.

  15. Instability of a compressible circular free jet with consideration of the influence of the jet boundary layer thickness

    NASA Technical Reports Server (NTRS)

    Michalke, A.

    1977-01-01

    The instability of a circular jet was investigated by means of the inviscid linearized stability theory. By variation of a jet parameter which takes the ratio of jet radius to boundary layer thickness into account, the influence of axisymmetry on the spatial growth rate and disturbance phase velocity is studied. The influence of Mach number and temperature ratio is discussed. A comparison with measurements shows that the instability of a turbulent jet boundary layer may also be explained by these results.

  16. Optical properties of hybrid plasmonic structure on silicon using transparent conducting-silver nanoparticles–silicon dioxide layers: the role of conducting oxide layer thickness in antireflection

    NASA Astrophysics Data System (ADS)

    Sardana, Sanjay K.; Komarala, Vamsi K.

    2016-07-01

    The hybrid plasmonic antireflection layer (HPAL) consisting of silver nanoparticles (Ag NPs) sandwiched between indium tin oxide (ITO) and silicon dioxide (SiO2) thin layers is investigated for enhancing light absorption within a silicon wafer. The optimization of HPAL for minimizing reflection losses from silicon is carried out by tuning the ITO layer thickness, which also affects Ag NP morphology during the growth process. Light reflectivity of ∼10% is observed from the silicon integrated with HPAL in the 300–1100 nm spectral region, due to enhanced light forward scattering as compared to a reflectivity of 26% from the bare silicon wafer. We have also investigated the ITO–SiO2 double layer (without Ag NPs) effect in reflection reduction from the silicon, but the HPAL performed better in Ag NPs’ surface plasmon resonance (<600 nm) and off-resonance (900–1100 nm) wavelength regions as compared to the double layer. With the Ag NPs, the ITO layer thickness can be reduced from 70 nm to 30 nm for the maximum reflectance reduction from the silicon surface. The thin SiO2 capping layer on Ag NPs provides a better refractive index match for further reflectance reduction, and also acts as a protective layer from degradation of Ag NPs with time.

  17. Thick polymer light-emitting diodes with very high power efficiency using Ohmic charge-injection layers

    NASA Astrophysics Data System (ADS)

    Lu, Li Ping; Finlayson, Chris E.; Friend, Richard H.

    2014-02-01

    We demonstrate the optimization of single-layer polymer LED structures with active layers with thicknesses of the order of 1 micron. By using a combined approach of the addition of MoO3, as a bottom hole-injection layer, and the incorporation of such thick active layers, exceptionally high performance metrics are achieved. In particular, brightnesses of 1000 cd m-2 at driving voltages of only 6.8 V, corresponding to a power efficiency of 7.8 lm W-1, a current efficiency of 17.2 cd A-1, and external quantum efficiency of 5.6%, are reported for devices based on F8BT (Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)]). A side-by-side comparison, between the standard LED structure and hybrid structures, demonstrates that with MoO3 as bottom hole-injection layer, the electron and hole charge carriers are both giving space-charge limited current for both carriers due to the Ohmic contacts. The devices hence show improved charge carrier balance, and, most importantly, high brightness at low operational voltage. Such thick active-layer devices with high performance metrics, in addition to improved engineering and processing tolerances, are thus especially important for application to high-throughput device fabrication methods.

  18. The sub-ice platelet layer and its influence on freeboard to thickness conversion of Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Price, D.; Rack, W.; Langhorne, P. J.; Haas, C.; Leonard, G.; Barnsdale, K.

    2014-02-01

    This is an investigation to quantify the influence of the sub-ice platelet layer on satellite measurements of total freeboard and their conversion to thickness of Antarctic sea ice. The sub-ice platelet layer forms as a result of the seaward advection of supercooled ice shelf water from beneath ice shelves. This ice shelf water provides an oceanic heat sink promoting the formation of platelet crystals which accumulate at the sea ice-ocean interface. The build-up of this porous layer increases sea ice freeboard, and if not accounted for, leads to overestimates of sea ice thickness from surface elevation measurements. In order to quantify this buoyant effect, the solid fraction of the sub-ice platelet layer must be estimated. An extensive in situ data set measured in 2011 in McMurdo Sound in the south-western Ross Sea is used to achieve this. We use drill-hole measurements and the hydrostatic equilibrium assumption to estimate a mean value for the solid fraction of this sub-ice platelet layer of 0.16. This is highly dependent upon the uncertainty in sea ice density. We test this value with independent Global Navigation Satellite System (GNSS) surface elevation data to estimate sea ice thickness. We find that sea ice thickness can be overestimated by up to 19%, with a mean deviation of 12% as a result of the influence of the sub-ice platelet layer. It is concluded that in close proximity to ice shelves this influence should be considered universally when undertaking sea ice thickness investigations using remote sensing surface elevation measurements.

  19. The sub-ice platelet layer and its influence on freeboard to thickness conversion of Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Price, D.; Rack, W.; Langhorne, P. J.; Haas, C.; Leonard, G.; Barnsdale, K.

    2014-06-01

    This is an investigation to quantify the influence of the sub-ice platelet layer on satellite measurements of total freeboard and their conversion to thickness of Antarctic sea ice. The sub-ice platelet layer forms as a result of the seaward advection of supercooled ice shelf water from beneath ice shelves. This ice shelf water provides an oceanic heat sink promoting the formation of platelet crystals which accumulate at the sea ice-ocean interface. The build-up of this porous layer increases sea ice freeboard, and if not accounted for, leads to overestimates of sea ice thickness from surface elevation measurements. In order to quantify this buoyant effect, the solid fraction of the sub-ice platelet layer must be estimated. An extensive in situ data set measured in 2011 in McMurdo Sound in the southwestern Ross Sea is used to achieve this. We use drill-hole measurements and the hydrostatic equilibrium assumption to estimate a mean value for the solid fraction of this sub-ice platelet layer of 0.16. This is highly dependent upon the uncertainty in sea ice density. We test this value with independent Global Navigation Satellite System (GNSS) surface elevation data to estimate sea ice thickness. We find that sea ice thickness can be overestimated by up to 19%, with a mean deviation of 12% as a result of the influence of the sub-ice platelet layer. It is concluded that within 100 km of an ice shelf this influence might need to be considered when undertaking sea ice thickness investigations using remote sensing surface elevation measurements.

  20. Microtransfer printing of metal ink patterns onto plastic substrates utilizing an adhesion-controlled polymeric donor layer

    NASA Astrophysics Data System (ADS)

    Park, Ji-Sub; Choi, Jun-Chan; Park, Min-Kyu; Bae, Jeong Min; Bae, Jin-Hyuk; Kim, Hak-Rin

    2016-06-01

    We propose a method for transfer-printed electrode patterns onto flexible/plastic substrates, specifically intended for metal ink that requires a high sintering temperature. Typically, metal-ink-based electrodes cannot be picked up for microtransfer printing because the adhesion between the electrodes and the donor substrate greatly increases after the sintering process due to the binding materials. We introduced a polymeric donor layer between the printed electrodes and the donor substrate and effectively reduced the adhesion between the Ag pattern and the polymeric donor layer by controlling the interfacial contact area. After completing a wet-etching process for the polymeric donor layer, we obtained Ag patterns supported on the fine polymeric anchor structures; the Ag patterns could be picked up onto the stamp surface even after the sintering process by utilizing the viscoelastic properties of the elastomeric stamp with a pick-up velocity control. The proposed method enables highly conductive metal-ink-based electrode patterns to be applied on thermally weak plastic substrates via an all-solution process. Metal electrodes transferred onto a film showed superior electrical and mechanical stability under the bending stress test required for use in printed flexible electronics.

  1. Development of the convective boundary layer capping with a thick neutral layer in Badanjilin: Observations and simulations

    NASA Astrophysics Data System (ADS)

    Han, Bo; Lü, Shihua; Ao, Yinhuan

    2012-01-01

    In this study, the development of a convective boundary layer (CBL) in the Badanjilin region was investigated by comparing the observation data of two cases. A deep neutral layer capped a CBL that occurred on 30 August 2009. This case was divided into five sublayers from the surface to higher atmospheric elevations: surface layer, mixed layer, inversion layer, neutral layer, and sub-inversion layer. The development process of the CBL was divided into three stages: S1, S2, and S3. This case was quite different from the development of the three-layer CBL observed on 31 August 2009 because the mixed layer of the five-layer CBL (CBL5) eroded the neutral layer during S2. The specific initial structure of the CBL5 was correlated to the synoptic background of atmosphere during nighttime. The three-stage development process of the CBL5 was confirmed by six simulations using National Center for Atmospheric Research (USA) large-eddy simulation (NCAR-LES), and some of its characteristics are presented in detail.

  2. Dust devil height and spacing with relation to the martian planetary boundary layer thickness

    NASA Astrophysics Data System (ADS)

    Fenton, Lori K.; Lorenz, Ralph

    2015-11-01

    In most remote and unmonitored places, little is known about the characteristics of daytime turbulent activity. Few processes render the optically transparent atmospheres of Earth and Mars visible; put more plainly, without clever instruments it is difficult to "see the unseen". To address this, we present a pilot study of images of martian dust devils (DDs) testing the hypothesis that DD height and spacing correlates with the thickness of the planetary boundary layer (PBL), h. The survey includes Context Camera (CTX) images from a 580 × 590 km2 area (196-208°E, 30-40°N) in northern Amazonis Planitia, spanning ∼3.6 Mars Years (MY) from Ls = 134.55°, MY 28 (13 November 2006) to Ls = 358.5°, MY 31 (28 July 2013). DD activity follows a repeatable seasonal pattern similar to that found in previous surveys, with a distinct "on" season during local summer, beginning shortly before the northern spring equinox (Ls = 0°) and lasting until just after the northern fall equinox (Ls = 180°). DD heights measured from shadow lengths varied considerably, with median values peaking at local midsummer. Modeled PBL heights, constrained by those measured from radio occultation data, follow a similar seasonal trend, and correlation of the two suggests that the martian PBL thickness is approximately 5 times the median DD height. These results compare favorably to the limited terrestrial data available. DD spacing was measured using nearest neighbor statistics, following the assumption that because convection cell widths have been measured to be ∼1.2 ± 0.2h (Willis, G.E., Deardorff, J.W. [1979]. J. Geophys. Res. 84(C1), 295-302), a preference for DD formation at vertices of convection cells intersections could be used to estimate the PBL height. During local spring and summer, the DD average nearest neighbor (ANN) ranged from ∼1 to 2h, indicating that DD spacing does indeed correlate with PBL height. However, this result is complicated by two factors: (1) convection cell

  3. Drug release from various thicknesses of layered mats consisting of electrospun polycaprolactone and polyethylene oxide micro/nanofibers

    NASA Astrophysics Data System (ADS)

    Kim, Geunhyung; Yoon, Hyeon; Park, Yunkyung

    2010-09-01

    A new drug delivery system (DDS) consisting of electrospun nanofibers is proposed. Layered mats of hydrophobic polycaprolactone (PCL) and polyethylene oxide (PEO) nanofibers were prepared successfully in a layer-by-layer manner using an electrospinning process. The PEO mat and drug were co-electrospun as a drug reservoir. Drug release rate was controlled physically by the thickness of the electrospun nanofibrous PCL layer, and its release behavior was examined over time. Release tests showed that the release behavior and the amount of initial burst of the drug were critically dependent on the thickness of the nanofibrous PCL mat. The release of drug showed a linear relationship with the thickness of the porous electrospun PCL mat. In addition, to demonstrate the feasibility of this type of DDS, the release behavior of the antimicrobial peptide HPA3NT3 from the nanofiber system was examined. The release of the peptide was easily controlled by the PCL nanofiber thickness and the released peptide did not lose biological activity.

  4. The Influence of Irradiation Time and Layer Thickness on Elution of Triethylene Glycol Dimethacrylate from SDR® Bulk-Fill Composite

    PubMed Central

    Jakubowska, Katarzyna; Chlubek, Dariusz; Buczkowska-Radlińska, Jadwiga

    2016-01-01

    Objective. This study aimed to evaluate triethylene glycol dimethacrylate (TEGDMA) elution from SDR bulk-fill composite. Methods. Three groups of samples were prepared, including samples polymerized in a 4 mm layer for 20 s, in a 4 mm layer for 40 s, and in a 2 mm layer for 20 s. Elution of TEGDMA into 100% ethanol, a 75% ethanol/water solution, and distilled water was studied. The TEGDMA concentration was measured using HPLC. Results. The TEGDMA concentration decreased in the following order: 100% ethanol > 75% ethanol > distilled water. Doubling the energy delivered to the 4 mm thick sample caused decrease (p < 0.05) in TEGDMA elution to distilled water. In ethanol solutions, the energy increase had no influence on TEGDMA elution. Decreasing the sample thickness resulted in decrease (p < 0.05) in TEGDMA elution for all the solutions. Conclusions. The concentration of eluted TEGDMA and the elution time were both strongly affected by the hydrophobicity of the solvent. Doubling the energy delivered to the 4 mm thick sample did not decrease the elution of TEGDMA but did decrease the amount of the monomer available to less aggressive solvents. Elution of TEGDMA was also correlated with the exposed sample surface area. Clinical Relevance. Decreasing the SDR layer thickness decreases TEGDMA elution. PMID:27366742

  5. Mussel-Inspired Polydopamine-Functionalized Graphene as a Conductive Adhesion Promoter and Protective Layer for Silver Nanowire Transparent Electrodes.

    PubMed

    Miao, Jinlei; Liu, Haihui; Li, Wei; Zhang, Xingxiang

    2016-05-31

    For the scalable fabrication of transparent electrodes and optoelectronic devices, excellent adhesion between the conductive films and the substrates is essential. In this work, a novel mussel-inspired polydopamine-functionalized graphene/silver nanowire hybrid nanomaterial for transparent electrodes was fabricated in a facile manner. Graphene oxide (GO) was functionalized and reduced by polydopamine while remaining stable in water without precipitation. It is shown that the polydopamine-functionalized GO (PFGO) film adhered to the substrate much more easily and more uniformly than the GO film. The PFGO film had a sheet resistance of ∼3.46 × 10(8) Ω/sq and a transparency of 78.2%, with excellent thermal and chemical stability; these characteristics are appropriate for antistatic coatings. Further reduced PFGO (RPFGO) as a conductive adhesion promoter and protective layer for the Ag nanowire (AgNW) significantly enhanced the adhesion force between AgNW networks and the substrate. The RPFGO-AgNW electrode was found to have a sheet resistance of 63 Ω/sq and a transparency of 70.5%. Moreover, the long-term stability of the RPFGO-AgNW electrode was greatly enhanced via the effective protection of the AgNW by RPFGO. These solution-processed antistatic coatings and electrodes have tremendous potential in the applications of optoelectronic devices as a result of their low production cost and facile processing. PMID:27142815

  6. Study of carrier recombination transient characteristics in MOCVD grown GaN dependent on layer thickness

    SciTech Connect

    Gaubas, E. Čeponis, T.; Jasiunas, A.; Jelmakas, E.; Juršėnas, S.; Kadys, A.; Malinauskas, T.; Tekorius, A.; Vitta, P.

    2013-11-15

    The MOCVD grown GaN epi-layers of different thickness have been examined in order to clarify a role of surface recombination, to separate an impact of radiative and non-radiative recombination and disorder factors. The microwave probed –photoconductivity (MW-PC) and spectrally resolved photo-luminescence (PL) transients were simultaneously recorded under ultraviolet (UV) light 354 nm pulsed 500 ps excitation. The MW-PC transients exhibited the carrier decay components associated with carrier decay within micro-crystals and the disordered structure on the periphery areas surrounding crystalline columns. Three PL bands were resolved within PL spectrum, namely, the exciton ascribed UV-PL band edge for hν>3.3 eV, blue B-PL band for 2.5 < hν < 3.0 eV and yellow Y-PL band with hν < 2.4 eV. It has been obtained that intensity of UV-PL band increases with excitation density, while intensity of B-PL band is nearly invariant. However, intensity of the Y-PL increases with reduction of the excitation density. The Y-PL can be associated with trapping centers. A reduction of UV excitation density leads to a decrease of the relative amplitude of the asymptotic component within the MW-PC transients and to an increase of the amplitude as well as duration of the yellow spectral band (Y-PL) asymptotic component. Fractional index α with values 0.5 < α < 0.8 was evaluated for the stretched-exponent component which fits the experimental transients determined by the disordered structure ascribed to the periphery areas surrounding the crystalline columns.

  7. Black sea surface temperature anomaly on 5th August 1998 and the ozone layer thickness

    NASA Astrophysics Data System (ADS)

    Manev, A.; Palazov, K.; Raykov, St.; Ivanov, V.

    2003-04-01

    BLACK SEA SURFACE TEMPERATURE ANOMALY ON 5th AUGUST 1998 AND THE OZONE LAYER THICKNESS A. Manev , K. Palazov , St. Raykov, V. Ivanov Solar Terrestrial Influences Laboratory, Bulgarian Academy of Sciences amanev@abv.bg This paper focuses on the peculiarities of the Black Sea surface temperature anomaly on 05.08.1998. Researching the daily temperature changes in a number of control fields in the course of 8-10 years, we have found hidden correlations and anomalous deviations in the sea surface temperatures on a global scale. Research proves the statistical reliability of the temperature anomaly on the entire Black Sea surface registered on 04.-05.08.1998. In the course of six days around these dates the temperatures are up to 2°C higher than the maximum temperatures in this period in the other seven years. A more detailed analysis of the dynamics of the anomaly required the investigation of five Black Sea surface characteristic zones of 75x75 km. The analysis covers the period 20 days - 10 days before and 10 days after the anomaly. Investigations aimed at interpreting the reasons for the anomalous heating of the surface waters. We have tried to analyze the correlation between sea surface temperature and the global ozone above the Black Sea by using simultaneously data from the two satellite systems NOAA and TOMS. Methods of processing and comparing the data from the two satellite systems are described. The correlation coefficients values for the five characteristic zones are very high and close, which proves that the character of the correlation ozone - sea surface temperature is the same for the entire Black Sea surface. Despite the high correlation coefficient, we have proved that causality between the two phenomena at the time of the anomaly does not exit.

  8. Pigments analysis and gold layer thickness evaluation of polychromy on wood objects by PXRF.

    PubMed

    Blonski, M S; Appoloni, C R

    2014-07-01

    The X-ray fluorescence technique by energy dispersion (EDXRF), being a multi elemental and non-destructive technique, has been widely used in the analysis of artworks and archeometry. An X-ray fluorescence portable equipment from the Laboratory of Applied Nuclear Physics of the State University of Londrina (LFNA/UEL) was used for the measurement of pigments in golden parts of a Gilding Preparation Standard Plaque and also pigments measurement on the Wood Adornment of the High Altar Column of the Side Pulpit of the Immaculate Conception Church Parish Sao Paulo-SP. The portable X-ray fluorescence PXRF-LFNA-02 consists of an X-ray tube with Ag anode, a Si-PIN detector (FWHM=221 eV for Mn line at 5.9 keV), a chain of electronics nuclear standard of X-ray spectrometer, a multichannel 8K, a notebook and a mechanical system designed for the positioning of detector and X-ray tube, which allows movements with two degrees of freedom from the system of excitation-detection. The excitation-detection time of each measurement was 100 and 500 s, respectively. The presence of elements Ti, Cr, Fe, Cu, Zn and Au was found in the golden area of the Altar Column ornament. On the other hand, analysis of the ratios for the intensities of Kα/Kβ lines measured in the areas made it possible to explore the possibility of measuring the stratigraphies of the layers of pigments and to estimate the thickness of the same. PMID:24583963

  9. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    NASA Astrophysics Data System (ADS)

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-11-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

  10. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    PubMed Central

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-01-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5–2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0–2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed. PMID:26527044

  11. Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

    PubMed Central

    dos Santos, Valentin Aranha; Schmetterer, Leopold; Triggs, Graham J.; Leitgeb, Rainer A.; Gröschl, Martin; Messner, Alina; Schmidl, Doreen; Garhofer, Gerhard; Aschinger, Gerold; Werkmeister, René M.

    2016-01-01

    In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 – 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume. PMID:27446696

  12. Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT.

    PubMed

    Dos Santos, Valentin Aranha; Schmetterer, Leopold; Triggs, Graham J; Leitgeb, Rainer A; Gröschl, Martin; Messner, Alina; Schmidl, Doreen; Garhofer, Gerhard; Aschinger, Gerold; Werkmeister, René M

    2016-07-01

    In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 - 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume. PMID:27446696

  13. Real-Space Direct Visualization of the Layer-Dependent Roughening Transition in Nanometer-Thick Pb Films

    NASA Astrophysics Data System (ADS)

    Calleja, F.; Passeggi, M. C. G., Jr.; Hinarejos, J. J.; de Parga, A. L. Vázquez; Miranda, R.

    2006-11-01

    By means of variable-temperature scanning tunneling microscopy and spectroscopy we studied the thickness-dependent roughening temperature of Pb films grown on Cu(111), whose electronic structure and total energy is controlled by quantum well states created by the spatial confinement of electrons. Large scale STM images are employed to quantify the layer population, i.e., the fraction of the surface area covered by different Pb thicknesses, directly in the real space as a function of temperature. The roughening temperature oscillates repeatedly with bilayer periodicity plus a longer beating period, mirroring the thickness dependence of surface energy calculations. Conditions have been found to stabilize at 300 K Pb films of particular magic thicknesses, atomically flat over microns.

  14. An improved layer-by-layer self-assembly technique to generate biointerfaces for platelet adhesion studies: Dynamic LbL

    NASA Astrophysics Data System (ADS)

    Lopez, Juan Manuel

    Layer-by-layer self-assembly (LbL) is a technique that generates engineered nano-scale films, coatings, and particles. These nanoscale films have recently been used in multiple biomedical applications. Concurrently, microfabrication methods and advances in microfluidics are being developed and combined to create "Lab-on-a-Chip" technologies. The potential to perform complex biological assays in vitro as a first-line screening technique before moving on to animal models has made the concept of lab on a chip a valuable research tool. Prior studies in the Biofluids Laboratory at Louisiana Tech have used layer-by-layer and in vitro biological assays to study thrombogenesis in a controlled, repeatable, engineered environment. The reliability of these previously established techniques was unsatisfactory for more complex cases such as chemical and shear stress interactions. The work presented in this dissertation was performed to test the principal assumptions behind the established laboratory methodologies, suggest improvements where needed, and test the impact of these improvements on accuracy and repeatability. The assumptions to be tested were: (1) The fluorescence microscopy (FM) images of acridine orange-tagged platelets accurately provide a measure of percent area of surface covered by platelets; (2) fibrinogen coatings can be accurately controlled, interact with platelets, and do not interfere with the ability to quantify platelet adhesion; and (3) the dependence of platelet adhesion on chemical agents, as measured with the modified methods, generally agrees with results obtained from our previous methods and with known responses of platelets that have been documented in the literature. The distribution of fibrinogen on the final LbL surface generated with the standard, static process (s-LbL) was imaged by tagging the fibrinogen with an anti-fibrinogen antibody bound to fluorescein isothiocyanate (FITC). FITC FM images and acridine orange FM images were taken

  15. Measuring sub-nm adsorbed water layer thickness and desorption rate using a fused-silica whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2014-05-01

    We report an optical method for measuring the thickness of the water layer adsorbed onto the surface of a high-Q fused-silica microresonator. Light from a tunable diode laser operating near 1550 nm is coupled into the microresonator to excite whispering-gallery modes (WGMs). By observing thermal distortion or even bistability of the WGM resonances caused by absorption in the water layer, the contribution of that absorption to the total loss is determined. Thereby, the thickness of the water layer is found to be ˜0.1 nm (approximately one monolayer). This method is further extended to measure the desorption rate of the adsorbed water, which is roughly exponential with a decay time of ˜40 h when the fused-silica microresonator is held in a vacuum chamber at low pressure.

  16. Correlation of Outer Nuclear Layer Thickness With Cone Density Values in Patients With Retinitis Pigmentosa and Healthy Subjects

    PubMed Central

    Menghini, Moreno; Lujan, Brandon J.; Zayit-Soudry, Shiri; Syed, Reema; Porco, Travis C.; Bayabo, Kristine; Carroll, Joseph; Roorda, Austin; Duncan, Jacque L.

    2015-01-01

    Purpose. We studied the correlation between outer nuclear layer (ONL) thickness and cone density in normal eyes and eyes with retinitis pigmentosa (RP). Methods. Spectral-domain optical coherence tomography (SD-OCT) scans were acquired using a displaced pupil entry position of the scanning beam to distinguish Henle's fiber layer from the ONL in 20 normal eyes (10 subjects) and 12 eyes with RP (7 patients). Cone photoreceptors were imaged using adaptive optics scanning laser ophthalmoscopy. The ONL thickness and cone density were measured at 0.5° intervals along the horizontal meridian through the fovea nasally and temporally. The ONL thickness and cone density were correlated using Spearman's rank correlation coefficient r. Results. Cone densities averaged over the central 6° were lower in eyes with RP than normal, but showed high variability in both groups. The ONL thickness and cone density were significantly correlated when all retinal eccentricities were combined (r = 0.74); the correlation for regions within 0.5° to 1.5° eccentricity was stronger (r = 0.67) than between 1.5° and 3.0° eccentricity (r = 0.23). Although cone densities were lower between 0.5° and 1.5° in eyes with RP, ONL thickness measures at identical retinal locations were similar in the two groups (P = 0.31), and interindividual variation was high for ONL and cone density measures. Although ONL thickness and retinal eccentricity were important predictors of cone density, eccentricity was over 3 times more important. Conclusions. The ONL thickness and cone density were correlated in normal eyes and eyes with RP, but both were strongly correlated with retinal eccentricity, precluding estimation of cone density from ONL thickness. (ClinicalTrials.gov number, NCT00254605.) PMID:25515570

  17. influence of film thickness on optical constants of antimony-based bismuth-doped super-resolution mask layer

    NASA Astrophysics Data System (ADS)

    Lu, Xinmiao; Wu, Yiqun; Wang, Yang; Wei, Jinsong

    As the demand for ultrahigh density information storage continues to grow, recording mark size of several tens nanometer which is smaller than the optical diffraction limit is required in optical memory. Functional film super-resolution technique is one of practical approaches to overcome the optical diffraction limit. Optical constants are important parameters to optical films as super-resolution masks. In this paper, the influence of film thickness on optical constants of antimony-based bismuth-doped super-resolution mask layer is investigated. The structure of the samples with different thickness was studied by X-ray diffraction. The transmission spectrum was measured by spectrophotometry. The optical constants of the films in the range of 300-800 nm were measured by spectroscopic ellipsometry. The results show that the structure of the film transforms from amorphous state to crystal state when the thickness increases from 7 nm to 300 nm. In the range of 300-800 nm, the refractive index and extinction coefficient increase with increasing wavelength. The transmission decreases rapidly when the thickness increases from 7 nm to 30 nm. The influences of film thickness on optical constants are more significant in the thickness range of 7-50 nm than that in the thickness above 50 nm.

  18. Whole field strain measurement in critical thin adhesive layer of single- and double-sided repaired CFRP panel using DIC

    NASA Astrophysics Data System (ADS)

    Kashfuddoja, Mohammad; Ramji, M.

    2015-03-01

    In the present work, the behavior of thin adhesively layer in patch repaired carbon fiber reinforced polymer (CFRP) panel under tensile load is investigated experimentally using digital image correlation (DIC) technique. The panel is made of Carbon/epoxy composite laminate and the stacking sequence in the panel is [0º]4. A circular hole of 10 mm diameter (d) is drilled at the center of the panel to mimic the case of low velocity impact damage removal. The panel with open hole is repaired with double sided (symmetrical) and single sided (unsymmetrical) rectangular patch made of same panel material having stacking sequence of [0º]3. Araldite 2011 is used for bonding the patch onto the panel over the damaged area. The global behavior of thin adhesive layer is examined by analyzing whole field strain distribution using DIC. Longitudinal, peel and shear strain field in both double and single sided repair configuration is studied and a compression is made between them. An estimate of shear transfer length which is an essential parameter in arriving at an appropriate overlap length in patch design is proposed from DIC and FEA. Damage development, failure mechanism and load displacement behavior is also investigated. The experimental results are compared with the numerical predictions.

  19. Design of long period fiber grating with optimal sensitivity for detecting adhesion of nano-layer on the fiber surface

    NASA Astrophysics Data System (ADS)

    Biswas, Palas; Dey, Tanoy Kumar; Basumallick, Nandini; Sinha, Prasanta Kumar; Dasgupta, Kamal; Bandyopadhyay, Somnath

    2014-05-01

    For detecting bio-molecular interaction using long period grating (LPG) we believe that a quantitative data concerning sensitivity for addition of layers on the surface and subsequently to optimize the same appears to be more usefull than defining LPG sensitivity for a surrounding refractive index change in bulk form. For the first time, to the best of our knowledge, we quantify the shift of resonant wavelength (Δλres) of the mode of interest around the transition point as a function of unit bi-layer thickness (Δd) of poly-electrolyte, deposited by ionic self assembly, and subsequently optimize the sensitivity Δλres/Δd. Experimental result show that a shift of ~12.5 nm/bi-layer is possible with optimum number of bi-layer deposition.

  20. Measurements of the Stiffness and Thickness of the Pavement Asphalt Layer Using the Enhanced Resonance Search Method

    PubMed Central

    Zakaria, Nur Mustakiza; Yusoff, Nur Izzi Md.; Hardwiyono, Sentot; Mohd Nayan, Khairul Anuar

    2014-01-01

    Enhanced resonance search (ERS) is a nondestructive testing method that has been created to evaluate the quality of a pavement by means of a special instrument called the pavement integrity scanner (PiScanner). This technique can be used to assess the thickness of the road pavement structure and the profile of shear wave velocity by using the principle of surface wave and body wave propagation. In this study, the ERS technique was used to determine the actual thickness of the asphaltic pavement surface layer, while the shear wave velocities obtained were used to determine its dynamic elastic modulus. A total of fifteen locations were identified and the results were then compared with the specifications of the Malaysian PWD, MDD UKM, and IKRAM. It was found that the value of the elastic modulus of materials is between 3929 MPa and 17726 MPa. A comparison of the average thickness of the samples with the design thickness of MDD UKM showed a difference of 20 to 60%. Thickness of the asphalt surface layer followed the specifications of Malaysian PWD and MDD UKM, while some of the values of stiffness obtained are higher than the standard. PMID:25276854

  1. Detection of subsurface defects and measurement of thickness of screen layers made of graphene and carbon nanotubes with application of full-field optical coherence tomography in Linnik configuration

    NASA Astrophysics Data System (ADS)

    Mlynarska, Paulina; Tomczewski, Slawomir; Pakuła, Anna; Wróblewski, Grzegorz; Sloma, Marcin; Salbut, Leszek

    2015-08-01

    Optical coherence tomography (OCT) is noncontact and nondestructive interferometric method which allows visualization of internal structure of an investigated sample. Till now it has found many applications in measurements of biological tissues, technical materials and conservation of art. Optical coherence tomography in full-field configuration is a great technique for visualization of subsurface structures of measured sample with high resolution. In this technique, en-face data acquisition is applied, which allows application of microscope objectives with high numerical aperture while the depth of field is not a problem. These objectives allow obtaining ultra high transverse resolution like in traditional microscopy. Additionally, light sources with broad spectrum, like low cost incandescent lamps (i.e. halogen lamp), allow measurements with micrometer scaleaxial resolution. In this paper the authors present application of full-field optical coherence tomography with a Linnik microscope for the thickness measurement of layers in flexible display with electrodes made of graphene and carbone nanotubes. Thicknesses of layer have a huge impact on the display parameters. There is a correlation between the thickness of the graphene layer and its electrical resistance. Graphene is a new and very promising material which is durable, flexible and has a good adhesion to diverse substrates. It gives a theoretical possibility to create flexible electronics, such as graphene bendable screens. Using OCT we can evaluate the quality of printed layers and detect subsurface defects.

  2. Differences of Intrasession Reproducibility of Circumpapillary Total Retinal Thickness and Circumpapillary Retinal Nerve Fiber Layer Thickness Measurements Made with the RS-3000 Optical Coherence Tomograph

    PubMed Central

    Kita, Yoshiyuki; Hollό, Gábor; Kita, Ritsuko; Horie, Daisuke; Inoue, Makoto; Hirakata, Akito

    2015-01-01

    Purpose To evaluate the intrasession reproducibility of various thickness parameters used to diagnose and follow-up glaucoma, in particular circumpapillary total retinal thickness (cpTR) provided by the RS-3000 optical coherence tomograph (OCT). Methods Fifty-three healthy eyes of 28 subjects underwent three consecutive imaging with the RS-3000 Advance OCT (NIDEK, Aichi,Japan) to evaluate the intrasession reproducibility of circumpapillary total retinal thickness (cpTR), circumpapillary retinal nerve fiber layer thickness (cpRNFL), macular ganglion cell complex thickness (mGCC) and macular total retina thickness (mTR) measurements. Intraclass correlation (ICC), coefficient of variation (CV) and reproducibility coefficient (RC) were calculated for each parameter. Results The ICC and CV values for mean cpTR and cpRNFL were 0.987 and 0.897, and 0.60% and 2.81%, respectively. The RC values for the mean cpTR and cpRNFL were 5.95 μm and 9.04 μm, respectively. For all cpTR parameters the ICC values were higher and both the CV and RC values were lower than those for the corresponding cpRNFL parameters. The ICC and CV values for superior mGCC, inferior mGCC, superior mTR and inferior mTR were 0.983, 0.980, 0.983 and 0.988, and 0.84%, 0.98%, 0.48% and 0.43%, respectively. The RC values for superior mGCC, inferior mGCC, superior mTR and inferior mTR were 2.86 μm, 3.12 μm, 4.41μm and 4.43 μm, respectively. Conclusions Intrasession reproducibility of cpTR, mGCC and mTR measurements made on healthy eyes was high. Repeatability of cpTR measurements was better than that of the corresponding cpRNFL measurements. These results suggest that future clinical investigations addressing detection of glaucoma and glaucomatous progression with the RS-3000 OCT may benefit from focusing on the cpTR parameters. PMID:26657805

  3. The impact of thickness and thermal annealing on refractive index for aluminum oxide thin films deposited by atomic layer deposition.

    PubMed

    Wang, Zi-Yi; Zhang, Rong-Jun; Lu, Hong-Liang; Chen, Xin; Sun, Yan; Zhang, Yun; Wei, Yan-Feng; Xu, Ji-Ping; Wang, Song-You; Zheng, Yu-Xiang; Chen, Liang-Yao

    2015-01-01

    The aluminum oxide (Al2O3) thin films with various thicknesses under 50 nm were deposited by atomic layer deposition (ALD) on silicon substrate. The surface topography investigated by atomic force microscopy (AFM) revealed that the samples were smooth and crack-free. The ellipsometric spectra of Al2O3 thin films were measured and analyzed before and after annealing in nitrogen condition in the wavelength range from 250 to 1,000 nm, respectively. The refractive index of Al2O3 thin films was described by Cauchy model and the ellipsometric spectra data were fitted to a five-medium model consisting of Si substrate/SiO2 layer/Al2O3 layer/surface roughness/air ambient structure. It is found that the refractive index of Al2O3 thin films decrease with increasing film thickness and the changing trend revised after annealing. The phenomenon is believed to arise from the mechanical stress in ALD-Al2O3 thin films. A thickness transition is also found by transmission electron microscopy (TEM) and SE after 900°C annealing. PMID:25852343

  4. The impact of thickness and thermal annealing on refractive index for aluminum oxide thin films deposited by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Wang, Zi-Yi; Zhang, Rong-Jun; Lu, Hong-Liang; Chen, Xin; Sun, Yan; Zhang, Yun; Wei, Yan-Feng; Xu, Ji-Ping; Wang, Song-You; Zheng, Yu-Xiang; Chen, Liang-Yao

    2015-02-01

    The aluminum oxide (Al2O3) thin films with various thicknesses under 50 nm were deposited by atomic layer deposition (ALD) on silicon substrate. The surface topography investigated by atomic force microscopy (AFM) revealed that the samples were smooth and crack-free. The ellipsometric spectra of Al2O3 thin films were measured and analyzed before and after annealing in nitrogen condition in the wavelength range from 250 to 1,000 nm, respectively. The refractive index of Al2O3 thin films was described by Cauchy model and the ellipsometric spectra data were fitted to a five-medium model consisting of Si substrate/SiO2 layer/Al2O3 layer/surface roughness/air ambient structure. It is found that the refractive index of Al2O3 thin films decrease with increasing film thickness and the changing trend revised after annealing. The phenomenon is believed to arise from the mechanical stress in ALD-Al2O3 thin films. A thickness transition is also found by transmission electron microscopy (TEM) and SE after 900°C annealing.

  5. In vivo sweat film layer thickness measured with Fourier-domain optical coherence tomography (FD-OCT)

    NASA Astrophysics Data System (ADS)

    Jonathan, Enock

    2008-06-01

    While human sweat secretion is accepted as a mechanism by which the body cools off, excessive sweating (hyperhidrosis) is now appreciated as a medical condition and the primary site for diagnosis is the palm of the hand. We propose sweat film layer thickness as a potential clinical diagnostic parameter when screening for excessive sweating. In this preliminary study we demonstrate the usefulness of Fourier-domain optical coherence tomography (FD-OCT) for measurement of sweat film thickness in vivo with micron-scale resolution on the hand of a human volunteer. FD-OCT has a superior image acquisition time and identification of active sweat glands, ducts and pores is also possible.

  6. Drug-eluting stent with improved durability and controllability properties, obtained via electrocoated adhesive promotion layer.

    PubMed

    Levy, Yair; Tal, Noam; Tzemach, Gilad; Weinberger, Judah; Domb, Abraham J; Mandler, Daniel

    2009-11-01

    Drug-eluting stents (DES) have become an accepted technology in intravascular intervention. Manufacturing methodologies of DES are based mainly on mechanical processes, which tend to generate coatings that have poor stability properties; these were recently related as a potential hazard. A novel approach for significantly increasing the adhesion of polymer coatings onto DES is presented. The method is based on the electrochemistry of diazonium salts. These substances are organic compounds with the characteristic structure of R-N(2) (+) X(-), where R is an organic residue and X(-) is an anion. The objective of this article is to study the properties of a selected diazonium salt 4-(1-dodecyloxy)-phenyldiazonium tetrafluoroborate, referred as C(12)-phenyldiazonium. This material was found to be a superior adhesive promoter for polymeric coatings applied onto metallic stents. C(12)-phenyldiazonium was synthesized and electrocoated on metallic stents and plates. The multilayer films of C(12)-phenyldiazonium were further characterized through electrochemical (cyclic voltammetry, impedance spectroscopy), physical (light and scanning electron microscopy, X-ray photoelectron spectroscopy, peeling tests), and chemical methodology (high pressure liquid chromatography). Further biocompatibility properties of the electrocoated basecoat were evaluated using in vitro and in vivo models. Synthesized C(12)-phenyldiazonium was successfully electrocoated onto metallic surfaces. Electrochemical tests demonstrated its efficient and controllable electrocoating. C(12)-phenyldiazonium was found to increase polymeric coating stability as was reflected by a standard adhesion test. Electrocoated metallic stents spray-coated with a second polymeric film showed improved durability following incubation in physiological buffer. Furthermore, this improvement in durability exhibits stabilized drug release. In addition, biocompatibility evaluations have demonstrated basecoat's inert properties

  7. Pull-out mechanical measurement of tissue-substrate adhesive strength: endothelial cell monolayer sheet formed on a thermoresponsive gelatin layer.

    PubMed

    Takamizawa, Keiichi; Shoda, Kaori; Matsuda, Takehisa

    2002-01-01

    Although adhesive strength of a single cell on substrates has been reported, the adhesive strength at the tissue-substrate interface has not been reported. However, the tissue-substrate adhesive strength must provide important criteria for performance of implant devices. This article deals with the tissue-substrate adhesive strength for fully endothelialized tissue, which was formed on commercial tissue culture dishes with or without a coating layer of thermoresponsive gelatin (poly(N-isopropylacrylamide)-grafted gelatin, which dissolves in water at room temperature but is precipitated at 37 degrees C). To determine tissue-substrate adhesive strength, a pull-out technique using a glue-coated cover glass was used. The adhesive strength of monolayered tissue on a noncoated dish was approximately 560 Pa or 230 nN/cell at 37 degrees C. For dishes coated with thermoresponsive gelatin, the adhesive strengths were 1050 Pa or 584 nN/cell at 37 degrees C, and 26 Pa or 14 nN/cell at room temperature. For noncoated dishes, delamination occurred mostly at the interface between the extracellular matrix (ECM) secreted by the cells and the dish surface; and for coated dishes, it took place fully at the interface between ECM and the dish surface. This technique enables determination of the adhesive strength between a full monolayered tissue and a substrate. PMID:12003077

  8. Magnetic and magnetoresistance studies of the evolution of the magnetic layer structure with Co layer thickness in electrodeposited Co-Cu/Cu multilayers

    NASA Astrophysics Data System (ADS)

    Ghosh, Subir Kumar; Chowdhury, Prashanta; Dogra, Anjana

    2013-02-01

    The structural transformation of electrochemically deposited Co-Cu/Cu multilayers with magnetic layer thickness was monitored via measurements of magnetization and magnetoresistance. For this, electrodeposition of [Co (tCo nm)/Cu (4 nm)]50 multilayers were carried out by varying the Co-layer thickness (tCo) down to 0.2 nm from a sulfate based single solution electrolyte. Magnetization measurements showed the appearance of anisotropy, increase in remanence magnetization and coercivity with systematic increase of tCo from 0.2 to 1 nm. Magnetic field direction dependent magnetoresistance (MR) measurements revealed that the isotropy in MR changes with tCo from tridimensional at 0.2 nm to in-plane at 0.4 nm to fully anisotropic at 1.0 nm. This illustrated that a fully granular magnetic Co-layer structure (tCo=0.2 nm) transforms into discontinuous layered one (tCo=0.4 nm) due to coalescence of suparparamagnetic regions to a continuous ferromagnetic layer (tCo=1 nm).

  9. Role of surface layer collagen binding protein from indigenous Lactobacillus plantarum 91 in adhesion and its anti-adhesion potential against gut pathogen.

    PubMed

    Yadav, Ashok Kumar; Tyagi, Ashish; Kaushik, Jai Kumar; Saklani, Asha Chandola; Grover, Sunita; Batish, Virender Kumar

    2013-12-14

    Human feacal isolates were ascertain as genus Lactobacillus using specific primer LbLMA1/R16-1 and further identified as Lactobacillus plantarum with species specific primers Lpl-3/Lpl-2. 25 L. plantarum strains were further assessed for hydrophobicity following the microbial adhesion to hydrocarbons (MATH) method and colonization potentials based on their adherence to immobilized human collagen type-1. Surface proteins were isolated from selected L. plantarum 91(Lp91) strain. The purified collagen binding protein (Cbp) protein was assessed for its anti-adhesion activity against enteric Escherichia coli 0157:H7 pathogen on immobilized collagen. Four L. plantarum strains displayed high degree of hydrophobicity and significant adhesion to collagen. A 72 kDa protein was purified which reduced 59.71% adhesion of E. coli 0157:H7 on immobilized collagen as compared to control well during adhesion assay. Cbp protein is the major influencing factor in inhibition of E. coli 0157:H7 adhesion with extracellular matrix (ECM) components. Hydrophobicity and adhesion potential are closely linked attributes precipitating in better colonization potential of the lactobacillus strains. Cbp is substantiated as a crucial surface protein contributing in adhesion of lactobacillus strains. The study can very well be the platform for commercialization of indigenous probiotic strain once their functional attributes are clinically explored. PMID:23890721

  10. Large Frequency Change with Thickness in Interlayer Breathing Mode--Significant Interlayer Interactions in Few Layer Black Phosphorus.

    PubMed

    Luo, Xin; Lu, Xin; Koon, Gavin Kok Wai; Castro Neto, Antonio H; Özyilmaz, Barbaros; Xiong, Qihua; Quek, Su Ying

    2015-06-10

    Bulk black phosphorus (BP) consists of puckered layers of phosphorus atoms. Few-layer BP, obtained from bulk BP by exfoliation, is an emerging candidate as a channel material in post-silicon electronics. A deep understanding of its physical properties and its full range of applications are still being uncovered. In this paper, we present a theoretical and experimental investigation of phonon properties in few-layer BP, focusing on the low-frequency regime corresponding to interlayer vibrational modes. We show that the interlayer breathing mode A(3)g shows a large redshift with increasing thickness; the experimental and theoretical results agree well. This thickness dependence is two times larger than that in the chalcogenide materials, such as few-layer MoS2 and WSe2, because of the significantly larger interlayer force constant and smaller atomic mass in BP. The derived interlayer out-of-plane force constant is about 50% larger than that of graphene and MoS2. We show that this large interlayer force constant arises from the sizable covalent interaction between phosphorus atoms in adjacent layers and that interlayer interactions are not merely of the weak van der Waals type. These significant interlayer interactions are consistent with the known surface reactivity of BP and have been shown to be important for electric-field induced formation of Dirac cones in thin film BP. PMID:25939057

  11. Analysis of an Interface Crack for a Functionally Graded Strip Sandwiched between Two Homogeneous Layers of Finite Thickness

    NASA Technical Reports Server (NTRS)

    Shbeeh, N. I.; Binienda, W. K.

    1999-01-01

    The interface crack problem for a composite layer that consists of a homogeneous substrate, coating and a non-homogeneous interface was formulated for singular integral equations with Cauchy kernels and integrated using the Lobatto-Chebyshev collocation technique. Mixed-mode Stress Intensity Factors and Strain Energy Release Rates were calculated. The Stress Intensity Factors were compared for accuracy with relevant results previously published. The parametric studies were conducted for the various thickness of each layer and for various non-homogeneity ratios. Particular application to the Zirconia thermal barrier on steel substrate is demonstrated.

  12. Trends in (LaMnO3)n/(SrTiO3)m superlattices with varying layer thicknesses

    PubMed Central

    Jilili, J.; Cossu, F.; Schwingenschlögl, U.

    2015-01-01

    We investigate the thickness dependence of the structural, electronic, and magnetic properties of (LaMnO3)n/(SrTiO3)m (n, m = 2, 4, 6, 8) superlattices using density functional theory. The electronic structure turns out to be highly sensitive to the onsite Coulomb interaction. In contrast to bulk SrTiO3, strongly distorted O octahedra are observed in the SrTiO3 layers with a systematic off centering of the Ti atoms. The systems favour ferromagnetic spin ordering rather than the antiferromagnetic spin ordering of bulk LaMnO3 and all show half-metallicity, while a systematic reduction of the minority spin band gaps as a function of the LaMnO3 and SrTiO3 layer thicknesses originates from modifications of the Ti dxy states. PMID:26323361

  13. Influence of the layer thickness and concentration of dye molecules on the emission amplification in cholesteric liquid crystals

    SciTech Connect

    Alaverdyan, R B; Gevorgyan, A A; Chilingaryan, A D; Chilingaryan, Yu S

    2008-05-31

    The propagation of light through a planar layer of a cholesteric liquid crystal doped with dye molecules is considered. The features of the emission spectra of the crystal are studied both in the absence and presence of dielectric boundaries. The increase in the emission intensity is investigated for different layer thicknesses and different concentrations of dye molecules. It is shown that an anomalously strong increase in the emission intensity with the diffraction intrinsic polarisation takes place in the case of a comparatively small crystal thickness and a relatively low concentration of dye molecules. The obtained results can be used for the development of miniature lasers with the circular polarisation of the fundamental radiation mode. (laser applications and other topics in quantum electronics)

  14. The influence of nickel layer thickness on microhardness and hydrogen sorption rate of commercially pure titanium alloy

    NASA Astrophysics Data System (ADS)

    Kudiiarov, V. N.; Kashkarov, E. B.; Syrtanov, M. S.; Yugova, I. S.

    2016-02-01

    The influence of nickel coating thickness on microhardness and hydrogen sorption rate by commercially pure titanium alloy was established in this work. Coating deposition was carried out by magnetron sputtering method with prior ion cleaning of surface. It was shown that increase of sputtering time from 10 to 50 minutes leads to increase coating thickness from 56 to 3.78 μm. It was established that increase of nickel coating thickness leads to increase of microhardness at loads less than 0.5 kg. Microhardness values for all samples are not significantly different at loads 1 kg. Hydrogen content in titanium alloy with nickel layer deposited at 10 and 20 minutes exceeds concentration in initial samples on one order of magnitude. Further increasing of deposition time of nickel coating leads to decreasing of hydrogen concentration in samples due to coating delamination in process of hydrogenation.

  15. Efficiency enhancement in solid state dye sensitized solar cells by including inverse opals with controlled layer thicknesses

    NASA Astrophysics Data System (ADS)

    Zheng, Hanbin; Shah, Said Karim; Abbas, Mamatimin; Ly, Isabelle; Rivera, Thomas; Almeida, Rui M.; Hirsch, Lionel; Toupance, Thierry; Ravaine, Serge

    2016-09-01

    The photoconversion efficiency of dye sensitized solar cells can be enhanced by the incorporation of light management nanostructures such as photonic crystals. Here, we present a facile route to incorporate titania inverse opals into solid state dye sensitized solar cells and report photoconversion efficiency enhancements of up to 56% compared with a model system without the inverse opal. Our approach is based on the precise design of titania inverse opals with a predetermined thickness that can be controlled at the individual layer level. By choosing an inverse opal exhibiting a photonic bandgap which overlaps the absorption bands of the dye, our results show that there is an optimal thickness of the inverse opal structure for maximum efficiency enhancement of the cell. This is the first experimental proof that the thickness of a titania inverse opal plays a pivotal role in cell efficiency enhancement in solid state dye sensitized solar cells.

  16. Effect of Refractive Status and Axial Length on Peripapillary Retinal Nerve Fibre Layer Thickness: An Analysis Using 3D OCT

    PubMed Central

    Sowmya, V.; Venkataramanan, V.R.

    2015-01-01

    Background Accurate measurement of retinal nerve fiber layer (RNFL) is now possible with the high resolution optical coherence tomography (OCT). Effect of refractive status of the eye on RNFL thickness may be relevant in the diagnosis of glaucoma and other optic nerve diseases. Aim To assess the RNFL thickness and compare its correlation with refractive status and axial length of the eye. Material and Methods Three hundred eyes of 150 patients were included in this study, who underwent RNFL analysis using TOPCON 3D OCT 2000. Analysis of variance has been used to find the significance of study parameters between the study groups. Results The study showed that refractive status/axial length affected the peripapillary RNFL thickness significantly. Conclusion The study suggests that the diagnostic accuracy of OCT may be improved by considering refractive status and axial length of the eye when RNFL is measured. PMID:26500931

  17. A Simple Method for Determining Heat Transfer, Skin Friction, and Boundary-Layer Thickness for Hypersonic Laminar Boundary-Layer Flows in a Pressure Gradient

    NASA Technical Reports Server (NTRS)

    Bertram, Mitchel H.; Feller, William V.

    1959-01-01

    A procedure based on the method of similar solutions is presented by which the skin friction, heat transfer, and boundary-layer thickness in a laminar hypersonic flow with pressure gradient may be rapidly evaluated if the pressure distribution is known. This solution, which at present is. restricted to power-law variations of pressure with surface distance, is presented for a wide range of exponents in the power law corresponding to both favorable and adverse pressure gradients. This theory has been compared to results from heat-transfer experiments on blunt-nose flat plates and a hemisphere cylinder at free-stream Mach numbers of 4 and 6.8. The flat-plate experiments included tests made at a Mach number of 6.8 over a range of angle of attack of +/- 10 deg. Reasonable agreement of the experimental and theoretical heat-transfer coefficients has been obtained as well as good correlation of the experimental results over the entire range of angle of attack studied. A similar comparison of theory with experiment was not feasible for boundary-layer-thickness data; however, the hypersonic similarity theory was found to account satisfactorily for the variation in boundary-layer thickness due to local pressure distribution for several sets of measurements.

  18. Adhesions of extracellular surface-layer associated proteins in Lactobacillus M5-L and Q8-L.

    PubMed

    Zhang, Yingchun; Xiang, Xinling; Lu, Qianhui; Zhang, Lanwei; Ma, Fang; Wang, Linlin

    2016-02-01

    Surface-layer associated proteins (SLAP) that envelop Lactobacillus paracasei ssp. paracasei M5-L and Lactobacillus casei Q8-L cell surfaces are involved in the adherence of these strain to the human intestinal cell line HT-29. To further elucidate some of the properties of these proteins, we assessed the yields and expressions of SLAP under different incubation conditions. An efficient and selective extraction of SLAP was obtained when cells of Lactobacillus were treated with 5 M LiCl at 37°C in aerobic conditions. The SLAP of Lactobacillus M5-L and Q8-L in cell extracts were visualized by SDS-PAGE and identified by Western blotting with sulfo-N-hydroxysuccinimide-biotin-labeled HT-29 cells as adhesion proteins. Atomic force microscopy contact imaging revealed that Lactobacillus strains M5-L and Q8-L normally display a smooth, homogeneous surface, whereas the surfaces of M5-L and Q8-L treated with 5 M LiCl were rough and more heterogeneous. Analysis of adhesion forces revealed that the initial adhesion forces of 1.41 and 1.28 nN obtained for normal Lactobacillus M5-L and Q8-L strains, respectively, decreased to 0.70 and 0.48 nN, respectively, following 5 M LiCl treatment. Finally, the dominant 45-kDa protein bands of Lactobacillus Q8-L and Lactobacillus M5-L were identified as elongation factor Tu and surface antigen, respectively, by liquid chromatography-tandem mass spectrometry. PMID:26709174

  19. Influences of solid/liquid boundary layer thickness and tilting angle on zone-refinement of germanium crystals

    NASA Astrophysics Data System (ADS)

    Yang, Gang; Guan, Yutong; Mei, Hao; Wang, Guojian; Mei, Dongming

    In zone-refining of metals, solid/liquid (S/L) boundary layer thickness has an influence on segregation coefficient of impurity atoms. Additionally, the segregation of impurity elements during zone refining can be maximized by adjusting the zone refinement tube with a proper angle. In this paper, we report the influences of S/L boundary layer thickness on the segregation coefficients of boron, phosphor, aluminum and gallium, which have been identified as four main impurities in germanium crystal by Photothermal Ionization Spectroscopy (PTIS). The thickness of S/L boundary layer was found by using a well-known model to fit the experimental data. The optimized segregation coefficients have been used to calculate the impurity distribution along the purified ingot. In addition, we have also optimized the tilting angle of the germanium ingot to investigate the impact on the segregation. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  20. Characterization of 7-nm-thick strained Ge-on-insulator layer fabricated by Ge-condensation technique

    NASA Astrophysics Data System (ADS)

    Nakaharai, Shu; Tezuka, Tsutomu; Sugiyama, Naoharu; Moriyama, Yoshihiko; Takagi, Shin-ichi

    2003-10-01

    A strained Ge-on-insulator (GOI) structure with a 7-nm-thick Ge layer was fabricated for applications to high-speed transistors. The GOI layer was formed by thermal oxidation of a strained SiGe layer grown epitaxially on a silicon-on-insulator (SOI) wafer. In transmission electron microscopy measurements, the obtained GOI layer exhibited a single-crystal structure with the identical orientation to an original SOI substrate and a smooth Ge/SiO2 interface. The rms of the surface roughness of the GOI layer was evaluated to be 0.4 nm by atomic force microscopy. The residual Si fraction in the GOI layer was estimated to be lower than the detection limit of Raman spectroscopy of 0.5% and also than the electron energy loss spectroscope measurements of 3%. It was found that the obtained GOI layer was compressively strained with a strain of 1.1%, which was estimated by the Raman spectroscopy. Judging from the observed crystal quality and the strain value, this technique is promising for fabrication of high-mobility strained Ge channel of high-performance GOI metal-insulator-semiconductor (MIS) transistors.

  1. Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion.

    PubMed

    Medeiros, Maria Isabel Dantas de; Carlo, Hugo Lemes; Lacerda-Santos, Rogério; Lima, Bruno Alessandro Guedes de; Souza, Frederico Barbosa de; Rodrigues, Jonas Almeida; Carvalho, Fabiola Galbiatti de

    2016-05-31

    The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM). Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10). The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva). Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukey's test and Student's t test (α = 0.05). After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish. PMID:27253145

  2. Adhesion of biologically inspired polymer microfibers on soft surfaces.

    PubMed

    Cheung, Eugene; Sitti, Metin

    2009-06-16

    Polymer microfiber arrays with mushroom-shaped tips are shown to adhere well to a soft, smooth substrate. An existing model describing the effect of backing layer thickness is also shown to be applicable to the adhesion of fibrillar arrays on soft surfaces. Simulations showed that adhesion can be enhanced by increasing the compliance of the microfibers in addition to maximizing single-fiber adhesion. This model can be used to guide the development of optimized microfiber adhesives for use on soft surfaces such as biological tissues or textiles. PMID:19449817

  3. Spectroscopic metrics allow in situ measurement of mean size and thickness of liquid-exfoliated few-layer graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Backes, Claudia; Paton, Keith R.; Hanlon, Damien; Yuan, Shengjun; Katsnelson, Mikhail I.; Houston, James; Smith, Ronan J.; McCloskey, David; Donegan, John F.; Coleman, Jonathan N.

    2016-02-01

    Liquid phase exfoliation is a powerful and scalable technique to produce defect-free mono- and few-layer graphene. However, samples are typically polydisperse and control over size and thickness is challenging. Notably, high throughput techniques to measure size and thickness are lacking. In this work, we have measured the extinction, absorption, scattering and Raman spectra for liquid phase exfoliated graphene nanosheets of various lateral sizes (90 <= <= 810 nm) and thicknesses (2.7 <= <= 10.4). We found all spectra to show well-defined dependences on nanosheet dimensions. Measurements of extinction and absorption spectra of nanosheet dispersions showed both peak position and spectral shape to vary with nanosheet thickness in a manner consistent with theoretical calculations. This allows the development of empirical metrics to extract the mean thickness of liquid dispersed nanosheets from an extinction (or absorption) spectrum. While the scattering spectra depended on nanosheet length, poor signal to noise ratios made the resultant length metric unreliable. By analyzing Raman spectra measured on graphene nanosheet networks, we found both the D/G intensity ratio and the width of the G-band to scale with mean nanosheet length allowing us to establish quantitative relationships. In addition, we elucidate the variation of 2D/G band intensities and 2D-band shape with the mean nanosheet thickness, allowing us to establish quantitative metrics for mean nanosheet thickness from Raman spectra.Liquid phase exfoliation is a powerful and scalable technique to produce defect-free mono- and few-layer graphene. However, samples are typically polydisperse and control over size and thickness is challenging. Notably, high throughput techniques to measure size and thickness are lacking. In this work, we have measured the extinction, absorption, scattering and Raman spectra for liquid phase exfoliated graphene nanosheets of various lateral sizes (90 <= <= 810 nm) and

  4. Tuning the thickness of electrochemically grafted layers in large area molecular junctions

    SciTech Connect

    Fluteau, T.; Bessis, C.; Barraud, C. Della Rocca, M. L.; Lafarge, P.; Martin, P.; Lacroix, J.-C.

    2014-09-21

    We have investigated the thickness, the surface roughness, and the transport properties of oligo(1-(2-bisthienyl)benzene) (BTB) thin films grafted on evaporated Au electrodes, thanks to a diazonium-based electro-reduction process. The thickness of the organic film is tuned by varying the number of electrochemical cycles during the growth process. Atomic force microscopy measurements reveal the evolution of the thickness in the range of 2–27 nm. Its variation displays a linear dependence with the number of cycles followed by a saturation attributed to the insulating behavior of the organic films. Both ultrathin (2 nm) and thin (12 and 27 nm) large area BTB-based junctions have then been fabricated using standard CMOS processes and finally electrically characterized. The electronic responses are fully consistent with a tunneling barrier in case of ultrathin BTB film whereas a pronounced rectifying behavior is reported for thicker molecular films.

  5. Translational Diffusion in Supported Rubberly Polymer Films at Different Layer Thicknesses

    NASA Astrophysics Data System (ADS)

    Pak, Hunkyun; Ellingson, Peter Christopher; Yu, Hyuk

    2002-03-01

    Translational diffusion of an organic dye with C18 hydrocarbon tail (4-octadecylamino-NBD) is examined in thin films of poly(isoprene) and poly(dimethylsiloxane) spincast on substrates. Surface functionalized silicon wafers were used as the substrates. Two kinds of surface functionalized wafers, one with predominantly methyl group and the other with primary amine group, were examined with respect to the diffusion as a function of film thickness over a range of 10-2000 nm. The diffusion coefficient was determined by the technique of fluorescence recovery after photobleaching and the film thickness by ellipsometry. The diffusion coefficient is found to reduce substantially from that in bulk polymers, vary by an order of magnitude over the thickness range, and its dependence is analyzed in terms of a simple model that takes into account of polymer interactions with the functionalized surfaces.

  6. Impacts of temperature increase and acidification on thickness of the surface mucopolysaccharide layer of the Caribbean coral Diploria spp.

    NASA Astrophysics Data System (ADS)

    Pratte, Zoe A.; Richardson, Laurie L.

    2014-06-01

    Coral mechanisms of resilience and resistance to stressors such as increasing sea surface temperature and ocean acidification must first be understood in order to facilitate the survival of coral reefs as we know them. One such mechanism is production of the protective surface mucopolysaccharide layer (SML). In this study, we investigated changes in the thickness of the SML in response to increasing temperature and acidification for the three Caribbean scleractinian coral species of the genus Diploria, which have been shown to exhibit differential resilience to disease and bleaching. Among the three species, Diploria strigosa is known to have a higher susceptibility to disease, Diploria labyrinthiformis is known to bleach more quickly, and Diploria clivosa is relatively unstudied. When temperature was increased from 25 to 31 °C over a 1- or 6-week period, the overall thickness of the SML decreased from 33 to 55 % for all three species. Average SML thickness at 25 °C for all three species ranged from 106 to 156 μm, while average thickness at 31 °C ranged from 64 to 86 μm. SML thickness was significantly different among species at 25 °C, but not at 31 °C. D. labyrinthiformis demonstrated lower fragment mortality due to thermal stress when compared to the other Diploria species. Acidification from pH 8.2 to 7.7 over 5 weeks had no effect on SML thickness for any species. The observed decrease in SML thickness in response to increased temperature might be attributed to a decrease in the production of mucus or an increase in the viscosity of the SML. These findings may help to explain the increased prevalence of coral disease during the warmer months, since increased temperature compromises an important aspect of coral innate immunity, as well as differences in disease and bleaching susceptibilities between Diploria species.

  7. Growth optimization and applicability of thick on-axis SiC layers using sublimation epitaxy in vacuum

    NASA Astrophysics Data System (ADS)

    Jokubavicius, Valdas; Sun, Jianwu; Liu, Xinyu; Yazdi, Gholamreza; Ivanov, Ivan. G.; Yakimova, Rositsa; Syväjärvi, Mikael

    2016-08-01

    We demonstrate growth of thick SiC layers (100-200 μm) on nominally on-axis hexagonal substrates using sublimation epitaxy in vacuum (10-5 mbar) at temperatures varying from 1700 to 1975 °C with growth rates up to 270 μm/h and 70 μm/h for 6H- and 4H-SiC, respectively. The stability of hexagonal polytypes are related to process growth parameters and temperature profile which can be engineered using different thermal insulation materials and adjustment of the induction coil position with respect to the graphite crucible. We show that there exists a range of growth rates for which single-hexagonal polytype free of foreign polytype inclusions can be maintained. Further on, foreign polytypes like 3C-SiC can be stabilized by moving out of the process window. The applicability of on-axis growth is demonstrated by growing a 200 μm thick homoepitaxial 6H-SiC layer co-doped with nitrogen and boron in a range of 1018 cm-3 at a growth rate of about 270 μm/h. Such layers are of interest as a near UV to visible light converters in a monolithic white light emitting diode concept, where subsequent nitride-stack growth benefits from the on-axis orientation of the SiC layer.

  8. Tuning the Thickness of Ba-Containing "Functional" Layer toward High-Performance Ceria-Based Solid Oxide Fuel Cells.

    PubMed

    Gong, Zheng; Sun, Wenping; Shan, Duo; Wu, Yusen; Liu, Wei

    2016-05-01

    Developing highly efficient ceria-based solid oxide fuel cells with high power density is still a big concern for commercial applications. In this work, a novel structured Ce0.8Sm0.2O2-δ (SDC)-based fuel cell with a bilayered anode consisting of Ni-SDC and Ni-BaZr0.1Ce0.7Y0.2O3-δ (Ni-BZCY) was designed. In addition to the catalysis function, the Ni-BZCY anode "functional" layer also provides Ba source for generating an electron-blocking layer in situ at the anode/electrolyte interface during sintering. The Ni-BZCY thickness significantly influences the quality of the electron-blocking layer and electrochemical performances of the cell. The cell with a 50 μm thick Ni-BZCY layer exhibits the best performance in terms of open circuit voltage (OCV) and peak power density (1068 mW cm(-2) at 650 °C). The results demonstrate that this cell with an optimal structure has a distinct advantage of delivering high power performance with a high efficiency at reduced temperatures. PMID:27078722

  9. Reduction of Thickness of N-Type Microcrystalline Hydrogenated Silicon Oxide Film Using Different Types of Seed Layer

    NASA Astrophysics Data System (ADS)

    Banerjee, Chandan; Sarker, Arindam; Barua, Asok K.

    2002-07-01

    By using a seeding technique it has been possible to reduce the thickness of n-μc-SiO:H film for use at the tunnel junction of a double-junction a-Si solar cell from ˜ 300 Å to ˜ 185 Å with acceptable optoelectronic properties. We have used two types of seed layer, i.e., undoped μc-SiO:H and μc-Si:H. The layers were prepared by the radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) method (13.56 MHz) at low rf power density (14 mW/cm2) and low substrate temperature (200°C). The ultrathin seed layer (˜ 40 Å) enhances the growth of microcrystallinity of the n-type μc-SiO:H film as confirmed by the results of transmission electron microscopy (TEM) analysis and Raman spectroscopy.

  10. Ocular Dominance Is Associated with the Ganglion Cell-Inner Plexiform Layer Thickness Profile in the Macula

    PubMed Central

    Choi, Jin A.; Kim, Jung-Sub; Jeong, Hyun Jin; Lee, Jin Ah; Park, Chan Kee

    2016-01-01

    Purpose To investigate the characteristics of macular ganglion cell-inner plexiform layer (GCIPL) thickness profiles associated with ocular dominance. Setting Private practice, Seoul, Republic of Korea. Design Comparative case-control study. Methods Both eyes of 199 participants with no ophthalmic abnormalities were included. Participants were imaged by spectral-domain optical coherence tomography, and underwent dominant eye testing using a hole-in-a-card test (sighting dominance) at the same visit. Macular GCIPL, as well as circumpapillary retinal nerve fiber layer (RNFL) thickness were compared for individual patients, according to ocular dominance. Results Ocular dominance occurred predominantly in the right eye (right vs. left: 72.36 vs. 27.60%; P < 0.001). In the comparison of macular GCIPL thickness, the average (81.27±5.01 μm vs. 80.66±6.31 μm in dominant vs. non-dominant eyes), inferonasal (81.39±5.47μm vs. 80.33±6.82μm, and inferior sectors (77.95±6.05μm vs. 76.97±8.15μm) were significantly different between dominant and non-dominant eyes (P = 0.040, 0.005, and 0.032, respectively). Significant predictors of average GCIPL thickness were spherical equivalent (β = 1.37, P<0.001), astigmatic power (β = 1.44, P = 0.009), disc area (β = 3.90, P < 0.001), average RNFL thickness (β = 0.22, P<0.001), average cup-to-disc ratio (β = 5.74, P = 0.002), difference between the inferior and superior quadrant RNFL thicknesses (β = 0.08, P = 0.024), and ocular dominance (β = 2.10, P = 0.020). On multivariate regression analysis, ocular dominance was correlated with average GCIPL thickness after adjusting for potential confounders (β = 1.63, P = 0.048). Conclusions Dominant eyes accompanied significantly thicker average macular GCIPL. This information suggests that macular GCIPL thickness may provide an indicator of the relative dominance of an eye. PMID:26918335

  11. The influence of vegetation and soil characteristics on active-layer thickness of permafrost soils in boreal forest.

    PubMed

    Fisher, James P; Estop-Aragonés, Cristian; Thierry, Aaron; Charman, Dan J; Wolfe, Stephen A; Hartley, Iain P; Murton, Julian B; Williams, Mathew; Phoenix, Gareth K

    2016-09-01

    Carbon release from thawing permafrost soils could significantly exacerbate global warming as the active-layer deepens, exposing more carbon to decay. Plant community and soil properties provide a major control on this by influencing the maximum depth of thaw each summer (active-layer thickness; ALT), but a quantitative understanding of the relative importance of plant and soil characteristics, and their interactions in determine ALTs, is currently lacking. To address this, we undertook an extensive survey of multiple vegetation and edaphic characteristics and ALTs across multiple plots in four field sites within boreal forest in the discontinuous permafrost zone (NWT, Canada). Our sites included mature black spruce, burned black spruce and paper birch, allowing us to determine vegetation and edaphic drivers that emerge as the most important and broadly applicable across these key vegetation and disturbance gradients, as well as providing insight into site-specific differences. Across sites, the most important vegetation characteristics limiting thaw (shallower ALTs) were tree leaf area index (LAI), moss layer thickness and understory LAI in that order. Thicker soil organic layers also reduced ALTs, though were less influential than moss thickness. Surface moisture (0-6 cm) promoted increased ALTs, whereas deeper soil moisture (11-16 cm) acted to modify the impact of the vegetation, in particular increasing the importance of understory or tree canopy shading in reducing thaw. These direct and indirect effects of moisture indicate that future changes in precipitation and evapotranspiration may have large influences on ALTs. Our work also suggests that forest fires cause greater ALTs by simultaneously decreasing multiple ecosystem characteristics which otherwise protect permafrost. Given that vegetation and edaphic characteristics have such clear and large influences on ALTs, our data provide a key benchmark against which to evaluate process models used to predict

  12. Wall energy and wall thickness of exchange-coupled rare-earth transition-metal triple layer stacks

    SciTech Connect

    Raasch, D.; Mathieu, C.

    1997-08-01

    The room-temperature wall energy {sigma}{sub w}=4.0{times}10{sup {minus}3}J/m{sup 2} of an exchange-coupled Tb{sub 19.6}Fe{sub 74.7}Co{sub 5.7}/Dy{sub 28.5}Fe{sub 43.2}Co{sub 28.3} double layer stack can be reduced by introducing a soft magnetic intermediate layer in between both layers exhibiting a significantly smaller anisotropy compared to Tb{endash}FeCo and Dy{endash}FeCo. {sigma}{sub w} will decrease linearly with increasing intermediate layer thickness, d{sub IL}, until the wall is completely located within the intermediate layer for d{sub IL}{ge}d{sub w}, where d{sub w} denotes the wall thickness. Thus, d{sub w} can be obtained from the plot {sigma}{sub w} versus d{sub IL}. We determined {sigma}{sub w} and d{sub w} on Gd{endash}FeCo intermediate layers with different anisotropy behavior (perpendicular and in-plane easy axis) and compared the results with data obtained from Brillouin light-scattering measurements, where exchange stiffness, A, and uniaxial anisotropy, K{sub u}, could be determined. With the knowledge of A and K{sub u}, wall energy and thickness were calculated and showed an excellent agreement with the magnetic measurements. A ten times smaller perpendicular anisotropy of Gd{sub 28.1}Fe{sub 71.9} in comparison to Tb{endash}FeCo and Dy{endash}FeCo resulted in a much smaller {sigma}{sub w}=1.1{times}10{sup {minus}3}J/m{sup 2} and d{sub w}=24nm at 300 K. A Gd{sub 34.1}Fe{sub 61.4}Co{sub 4.5} with in-plane anisotropy at room temperature showed a further reduced {sigma}{sub w}=0.3{times}10{sup {minus}3}J/m{sup 2} and d{sub w}=17nm. The smaller wall energy was a result of a different wall structure compared to perpendicular layers. {copyright} {ital 1997 American Institute of Physics.}

  13. Non-destructive evaluation of adhesive layer using a planar array capacitive imaging technology

    NASA Astrophysics Data System (ADS)

    Zhang, Yuyan; Zhao, Limei; Wen, Yintang; Sun, Dongtao

    2016-04-01

    The thermal protection materials for aircraft are usually assembled on the substrate surface by means of adhesion agent. It is very necessary to evaluate the interface bonding quality which has great influence on heat preservation performance. At present, there is still no relatively satisfactory and reliable method for defect detection of cohesive coating. Planar array electrical capacitance tomography (ECT) is a suitable non-invasive imaging technique when there is only limited access to the targeted object. This research aims to investigate the feasibility of using planar array electrical capacitive tomography for bondline defect detection. In this paper, a planar array ECT system is developed consist of a planar array sensor of 12 electrodes, a capacitance acquisition system and image reconstruction software. The sensor development, simulation of sensitivity map, practical application and imaging reconstruction are discussed. A series of specimens of thermal protection material with man-made defects are tested by the proposed planar array ECT system. The experimental results show that the defect in cohesive coating can be effectively detected and the minimum size can be detected is 10mm×10mm.

  14. Thickness management in three-dimensional laser manufacturing of suspended structures in a single SU-8 layer

    NASA Astrophysics Data System (ADS)

    Li, Biao; Gueit, Aurelien; Sharon, Andre

    2006-06-01

    Cantilevers, embedded channels, microcavities, and other high-aspect-ratio geometries requiring gaps between layers are essential to microfluidic components used for biotech/biomedical applications. Intensive efforts have been expanded in the development of novel approaches for efficiently manufacturing suspended structures. We have recently demonstrated a three-dimensional (3D) fabrication technique for rapid processing of microfluidic structures using a scanning laser system [B. Li et al. Appl. Phys. Lett. 85, 2426 (2004)]. This technique enables spot-by-spot laser pulsing for both in-plane and in-depth (parallel to film thickness) processing. Its maskless feature allows rapid prototyping of multilevel microfluidic structures at low cost. This article describes our latest results in thickness management using the 3D laser manufacturing technique. Suspended beams of various thicknesses have been fabricated by modifying grid size, laser energy, and degree of focus. Towards this end, we have demonstrated a microfluidic system with a functional microvalve in a single SU-8 layer.

  15. Impact of buffer layer and Pt thickness on the interface structure and magnetic properties in (Co/Pt) multilayers.

    PubMed

    Bersweiler, M; Dumesnil, K; Lacour, D; Hehn, M

    2016-08-24

    The influence of Pt thickness on the interface structure (roughness / intermixing) and magnetic properties has been investigated for (Co / Pt) multilayers sputtered on a Pt or a thin oxide (MgO or AlO x ) buffer layer. When Pt thickness increases from 1.2 nm-2.2 nm, we observe that the effective anisotropy increases with the Pt thickness, simultaneously with the decrease of roughness, i.e. the occurrence of sharper interfaces. Perpendicular magnetic anisotropy (PMA) is still achieved on the oxide buffer layers, but with a lower effective anisotropy correlated to more perturbed interfaces. The detailed analysis of the saturation magnetization shows that: (i) M s is significantly enhanced in the case of rough/intermixed interfaces, which is attributed to and discussed in the framework of Pt induced polarization, (ii) the change in volume dipolar anisotropy is the main factor responsible for the reduction of K eff for systems grown on oxides. Beyond the major role of volume dipolar contribution that reduces PMA, a supplemental positive contribution promoting PMA can be invoked for rough interfaces and large M s (deposit on oxide). This contribution is consistent with a dipolar surface anisotropy term and increases for rough interfaces, in contrast to the Néel surface anisotropy. These opposite variations may interestingly lead to an enhanced anisotropy in (Co / Pt) stackings grown on oxides compared to systems deposited on Pt, i.e. with sharper interfaces. PMID:27351776

  16. Impact of buffer layer and Pt thickness on the interface structure and magnetic properties in (Co/Pt) multilayers

    NASA Astrophysics Data System (ADS)

    Bersweiler, M.; Dumesnil, K.; Lacour, D.; Hehn, M.

    2016-08-01

    The influence of Pt thickness on the interface structure (roughness / intermixing) and magnetic properties has been investigated for (Co / Pt) multilayers sputtered on a Pt or a thin oxide (MgO or AlO x ) buffer layer. When Pt thickness increases from 1.2 nm–2.2 nm, we observe that the effective anisotropy increases with the Pt thickness, simultaneously with the decrease of roughness, i.e. the occurrence of sharper interfaces. Perpendicular magnetic anisotropy (PMA) is still achieved on the oxide buffer layers, but with a lower effective anisotropy correlated to more perturbed interfaces. The detailed analysis of the saturation magnetization shows that: (i) M s is significantly enhanced in the case of rough/intermixed interfaces, which is attributed to and discussed in the framework of Pt induced polarization, (ii) the change in volume dipolar anisotropy is the main factor responsible for the reduction of K eff for systems grown on oxides. Beyond the major role of volume dipolar contribution that reduces PMA, a supplemental positive contribution promoting PMA can be invoked for rough interfaces and large M s (deposit on oxide). This contribution is consistent with a dipolar surface anisotropy term and increases for rough interfaces, in contrast to the Néel surface anisotropy. These opposite variations may interestingly lead to an enhanced anisotropy in (Co / Pt) stackings grown on oxides compared to systems deposited on Pt, i.e. with sharper interfaces.

  17. Determination of Axial Length Requiring Adjustment of Measured Circumpapillary Retinal Nerve Fiber Layer Thickness for Ocular Magnification

    PubMed Central

    Hirasawa, Kazunori; Shoji, Nobuyuki; Yoshii, Yukako; Haraguchi, Shota

    2014-01-01

    Purpose To determine the axial length requiring adjustment of measured circumpapillary retinal nerve fiber layer (cpRNFL) thickness to account for ocular magnification during spectral-domain optical coherence tomography (SD-OCT). Methods In this prospective study, 148 eyes of 148 healthy student volunteers were imaged by two examiners using three-dimensional SD-OCT. In 54 randomly selected eyes, total cpRNFL thickness was measured with and without adjustment for ocular magnification to establish intra-examiner and inter-examiner measurement error. The 148 eyes were then divided into three groups according to the error values: control group (difference in the corrected and uncorrected total cpRNFL thickness was within the measurement error range), thinner group (the corrected total cpRNFL thickness was less than the uncorrected one), and thicker group (the corrected total cpRNFL thickness was more than the uncorrected one). The cutoff values of axial length between the control and the other groups were calculated by receiver operating characteristic analysis. Results Measurement error ranged from 4.2 to 5.3 µm; the threshold value was defined as 5.3 µm. The cutoff values of axial length between the thinner and the control groups and between the control and the thicker groups were 23.60 (area under the curve [AUC] = 0.959) and 25.55 (AUC = 0.944) mm, respectively. Conclusions Axial lengths shorter than 23.60 mm and longer than 25.55 mm require adjustment of measured cpRNFL thickness to account for ocular magnification during SD-OCT. Clinical Trial Registration UMIN Clinical Trials Registry (http://www.umin.ac.jp/) under unique trial number UMIN000013248 (date of registration: 02/24/2014) PMID:25215521

  18. Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome: one year follow-up results

    PubMed Central

    Zengin, Mehmet Ozgur; Tuncer, Ibrahim; Karahan, Eyyup

    2014-01-01

    AIM To investigate the retinal nerve fiber layer (RNFL) thickness changes in patients with obstructive sleep apnea syndrome (OSAS) for one year follow-up. To discuss the possibility of detecting tendency of glaucoma in this population by using spectral domain optical coherence tomography (3D-OCT-2000 Spectral domain). METHODS After polysomnographic study, all subjects (64 OSAS patients and 40 controls) underwent detailed ophthalmological examination. After these examinations, patients with glaucoma and patients who had ophthalmological and/or systemic disease were excluded from the study. Totally, 20 patients in OSAS group and five patients in controls were excluded from the study in the first examination and follow-up period. The RNFL thickness was assessed with OCT. Forty-four OSAS patients and 35 control subjects were followed up 12mo. RNFL thickness change and OSAS patients were evaluated for severity of disease by Apnea-Hypopnea Index (AHI). RESULTS Forty-four OSAS patients and 35 controls were enrolled in the study. Statistically significance was found between OSAS patients and controls at the 12th mo. Average RNFL thickness was found to be significantly lower in last measurements in OSAS patients when compared with first measurements and control subjects (P<0.001, 0.002, respectively). There was a statistically significant correlation among AHI, and RNFL thickness (P<0.05). CONCLUSION The results suggest that the patients with OSAS were related with a proportional decrease in the RNFL thickness. These patients should be followed up regularly for glaucomatous changes. Detecting more RNFL thinning in severe OSAS was important. PMID:25161947

  19. Optical coherence tomography assessed retinal nerve fiber layer thickness in patients with Alzheimer's disease: a meta-analysis

    PubMed Central

    He, Xue-Fei; Liu, Yi-Ting; Peng, Cheng; Zhang, Fan; Zhuang, Shi; Zhang, Jin-Song

    2012-01-01

    AIM To investigate the difference of retinal nerve fiber layer (RNFL) thickness between Alzheimer's disease patients and normal people, so as to provide clue for the early diagnosis of Alzheimer's disease. METHODS The articles on the association of RNFL thickness and Alzheimer's disease were retrieved by searching international and national databases. The qualified articles were assessed by meta analysis with Stata11.0 software. The results were pooled using weighted mean difference (WMD) with a corresponding 95% confidence interval (CI). RESULTS Totally 7 studies enrolled 324 eyes were included in the meta-analysis. The results of meta analysis showed that in AD patients, there was a significant average RNFL thickness reduction compared with the control group [WMD=-17.561, 95%CI: (-23.971, -11.151)]. There were significant differences in superior, inferior, nasal and temporal RNFL thickness between the two groups. WMD with a 95%CI were [-18.829, 95%CI:(-25.915, -11.743); P<0.05], [-25.775, 95%CI:(-34.304, -17.247); P<0.05], [-16.877, 95%CI: (-29.141, -4.613); P<0.001] and [-14.565, 95%CI:(-28.002, -1.128); P<0.001] respectively. Begg's test and Egger's test did not show significant difference, funnel plot was basically symmetrical, indicating that there was no publication bias existed. CONCLUSION There are significant differences in the RNFL thickness in all quadrants between the two groups. RNFL thickness is reduced in AD patients compared with the control group. PMID:22773997

  20. Full-thickness skin wound healing using autologous keratinocytes and dermal fibroblasts with fibrin: bilayered versus single-layered substitute.

    PubMed

    Idrus, Ruszymah Bt Hj; Rameli, Mohd Adha bin P; Low, Kiat Cheong; Law, Jia Xian; Chua, Kien Hui; Latiff, Mazlyzam Bin Abdul; Saim, Aminuddin Bin

    2014-04-01

    Split-skin grafting (SSG) is the gold standard treatment for full-thickness skin defects. For certain patients, however, an extensive skin lesion resulted in inadequacies of the donor site. Tissue engineering offers an alternative approach by using a very small portion of an individual's skin to harvest cells for propagation and biomaterials to support the cells for implantation. The objective of this study was to determine the effectiveness of autologous bilayered tissue-engineered skin (BTES) and single-layer tissue-engineered skin composed of only keratinocytes (SLTES-K) or fibroblasts (SLTES-F) as alternatives for full-thickness wound healing in a sheep model. Full-thickness skin biopsies were harvested from adult sheep. Isolated fibroblasts were cultured using medium Ham's F12: Dulbecco modified Eagle medium supplemented with 10% fetal bovine serum, whereas the keratinocytes were cultured using Define Keratinocytes Serum Free Medium. The BTES, SLTES-K, and SLTES-F were constructed using autologous fibrin as a biomaterial. Eight full-thickness wounds were created on the dorsum of the body of the sheep. On 4 wounds, polyvinyl chloride rings were used as chambers to prevent cell migration at the edge. The wounds were observed at days 7, 14, and 21. After 3 weeks of implantation, the sheep were euthanized and the skins were harvested. The excised tissues were fixed in formalin for histological examination via hematoxylin-eosin, Masson trichrome, and elastin van Gieson staining. The results showed that BTES, SLTES-K, and SLTES-F promote wound healing in nonchambered and chambered wounds, and BTES demonstrated the best healing potential. In conclusion, BTES proved to be an effective tissue-engineered construct that can promote the healing of full-thickness skin lesions. With the support of further clinical trials, this procedure could be an alternative to SSG for patients with partial- and full-thickness burns. PMID:24637651

  1. Optical coherence tomographic assessment of retinal nerve fiber layer thickness changes before and after glaucoma filtration surgery

    PubMed Central

    Sarkar, Kumaresh Chandra; Das, Palash; Pal, Ranabir; Shaw, Chattaranjan

    2014-01-01

    Background: Glaucomatous Optic Neuropathy (GON) is very common in the glaucoma patients, and impaired effect of glaucoma is measured by the Retinal Nerve Fiber Layer (RNFL) thickness. Objective: The study was conducted to find out the mean RNFL thickness, RNFL thickness in different quadrants, Intra-Ocular Pressure (IOP) changes, and visual field changes after filtration surgery in different ages and genders using Optical Coherence Tomography (OCT). Materials and Methods: The study was an interventional case-series conducted at the Glaucoma Clinic at the Regional Institute of Ophthalmology at Kolkata from March 2009 to August 2010. Fifty-one eyes of 43 open angle glaucoma patients had been selected for clinical and ophthalmologic evaluation. All the eyes of glaucoma patients who fulfilled the inclusion criteria were registered in the study population. The glaucoma filtration surgery was done in these patients. The RNFL thickness, IOP, visual field changes were measured before and after intervention of filtration surgery. Pre-operative OCT images of RNFL were obtained 0 to 120 days before surgery, and post-operative images were obtained from 60 to 120 days after surgery. Data collected in a standard data collection form included schedule. Results: Paired t-test was used. RNFL thickness was (pre-operative: 52.56 ± 17.40, post-operative: 58.48 ± 20.20, P < 0.0001) significantly increased after filtration surgery measured by OCT with significant reduction of IOP (r = - 0.38, P = 0.005) irrespective of age and gender. Conclusions: An increase in RNFL thickness was observed after glaucoma filtration surgery that correlated with IOP reduction. PMID:24799793

  2. Thickness-Dependent Binding Energy Shift in Few-Layer MoS2 Grown by Chemical Vapor Deposition.

    PubMed

    Lin, Yu-Kai; Chen, Ruei-San; Chou, Tsu-Chin; Lee, Yi-Hsin; Chen, Yang-Fang; Chen, Kuei-Hsien; Chen, Li-Chyong

    2016-08-31

    The thickness-dependent surface states of MoS2 thin films grown by the chemical vapor deposition process on the SiO2-Si substrates are investigated by X-ray photoelectron spectroscopy. Raman and high-resolution transmission electron microscopy suggest the thicknesses of MoS2 films to be ranging from 3 to 10 layers. Both the core levels and valence band edges of MoS2 shift downward ∼0.2 eV as the film thickness increases, which can be ascribed to the Fermi level variations resulting from the surface states and bulk defects. Grainy features observed from the atomic force microscopy topographies, and sulfur-vacancy-induced defect states illustrated at the valence band spectra imply the generation of surface states that causes the downward band bending at the n-type MoS2 surface. Bulk defects in thick MoS2 may also influence the Fermi level oppositely compared to the surface states. When Au contacts with our MoS2 thin films, the Fermi level downshifts and the binding energy reduces due to the hole-doping characteristics of Au and easy charge transfer from the surface defect sites of MoS2. The shift of the onset potentials in hydrogen evolution reaction and the evolution of charge-transfer resistances extracted from the impedance measurement also indicate the Fermi level varies with MoS2 film thickness. The tunable Fermi level and the high chemical stability make our MoS2 a potential catalyst. The observed thickness-dependent properties can also be applied to other transition-metal dichalcogenides (TMDs), and facilitates the development in the low-dimensional electronic devices and catalysts. PMID:27488185

  3. Inversion of surface wave data for subsurface shear wave velocity profiles characterized by a thick buried low-velocity layer

    NASA Astrophysics Data System (ADS)

    Farrugia, Daniela; Paolucci, Enrico; D'Amico, Sebastiano; Galea, Pauline

    2016-08-01

    The islands composing the Maltese archipelago (Central Mediterranean) are characterized by a four-layer sequence of limestones and clays. A common feature found in the western half of the archipelago is Upper Coralline Limestone (UCL) plateaus and hillcaps covering a soft Blue Clay (BC) layer which can be up to 75 m thick. The BC layer introduces a velocity inversion in the stratigraphy, implying that the VS30 (traveltime average sear wave velocity (VS) in the upper 30 m) parameter is not always suitable for seismic microzonation purposes. Such a layer may produce amplification effects, however might not be included in the VS30 calculations. In this investigation, VS profiles at seven sites characterized by such a lithological sequence are obtained by a joint inversion of the single-station Horizontal-to-Vertical Spectral Ratios (H/V or HVSR) and effective dispersion curves from array measurements analysed using the Extended Spatial Auto-Correlation technique. The lithological sequence gives rise to a ubiquitous H/V peak between 1 and 2 Hz. All the effective dispersion curves obtained exhibit a `normal' dispersive trend at low frequencies, followed by an inverse dispersive trend at higher frequencies. This shape is tentatively explained in terms of the presence of higher mode Rayleigh waves, which are commonly present in such scenarios. Comparisons made with the results obtained at the only site in Malta where the BC is missing below the UCL suggest that the characteristics observed at the other seven sites are due to the presence of the soft layer. The final profiles reveal a variation in the VS of the clay layer with respect to the depth of burial and some regional variations in the UCL layer. This study presents a step towards a holistic seismic risk assessment that includes the implications on the site effects induced by the buried clay layer. Such assessments have not yet been done for Malta.

  4. Correlation between skin, bone, and cerebrospinal fluid layer thickness and optical coefficients measured by multidistance frequency-domain near-infrared spectroscopy in term and preterm infants

    NASA Astrophysics Data System (ADS)

    Demel, Anja; Feilke, Katharina; Wolf, Martin; Poets, Christian F.; Franz, Axel R.

    2014-01-01

    Near-infrared spectroscopy (NIRS) is increasingly used in neonatal intensive care. We investigated the impact of skin, bone, and cerebrospinal fluid (CSF) layer thickness in term and preterm infants on absorption-(μa) and/or reduced scattering coefficients (μs‧) measured by multidistance frequency-domain (FD)-NIRS. Transcranial ultrasound was performed to measure the layer thicknesses. Correlations were only statistically significant for μa at 692 nm with bone thickness and μs‧ at 834 nm with skin thickness. There is no evidence that skin, bone, or CSF thickness have an important effect on μa and μs‧. Layer thicknesses of skin, bone, and CSF in the range studied do not seem to affect cerebral oxygenation measurements by multidistance FD-NIRS significantly.

  5. Drop impact onto a liquid layer of finite thickness: dynamics of the cavity evolution.

    PubMed

    Berberović, Edin; van Hinsberg, Nils P; Jakirlić, Suad; Roisman, Ilia V; Tropea, Cameron

    2009-03-01

    In the present work experimental, numerical, and theoretical investigations of a normal drop impact onto a liquid film of finite thickness are presented. The dynamics of drop impact on liquid surfaces, the shape of the cavity, the formation and propagation of a capillary wave in the crater, and the residual film thickness on the rigid wall are determined and analyzed. The shape of the crater within the film and the uprising liquid sheet formed upon the impact are observed using a high-speed video system. The effects of various influencing parameters such as drop impact velocity, liquid film thickness and physical properties of the liquids, including viscosity and surface tension, on the time evolution of the crater formation are investigated. Complementary to experiments the direct numerical simulations of the phenomena are performed using an advanced free-surface capturing model based on a two-fluid formulation of the classical volume-of-fluid (VOF) model in the framework of the finite volume numerical method. In this model an additional convective term is introduced into the transport equation for phase fraction, contributing decisively to a sharper interface resolution. Furthermore, an analytical model for the penetration depth of the crater is developed accounting for the liquid inertia, viscosity, gravity, and surface tension. The model agrees well with the experiments at the early times of penetration far from the wall if the impact velocity is high. Finally, a scaling analysis of the residual film thickness on the wall is conducted demonstrating a good agreement with the numerical predictions. PMID:19392048

  6. Collision dynamics of high-speed droplets upon layers of variable thickness

    NASA Astrophysics Data System (ADS)

    Pan, Kuo-Long; Cheng, Kai-Ren; Chou, Ping-Chung; Wang, Ching-Hua

    2008-09-01

    The collision dynamics between a droplet and a film has been studied with high-impact energy that can be grouped in a dimensionless Weber number, We, as normalized by surface energy. To accomplish this, we have developed a technique based on cutting of a high-speed jet, which can generate a single droplet with speed up to 23 m/s and We on the order of thousands. It was found that the boundaries indicating the occurrence of a central jet and that of a secondary droplet disintegrated from the jet decreased monotonically with increased dimensionless film thickness, H, and remained constant when the film thickness was larger than the crater depth. However, the transition designating multiple droplets that are originated from a central jet shows a non-monotonic trend with the variation of H, with a minimum We being at H ≈ 3, which is about the maximum crater depth, owing to a tuning behavior. The critical We for splashing that occurs at an early phase immediately after the impact is relatively sensitive to the film thickness only when H is between 1 and 2, which increases with reduced H. At large We (≳2,570 for high H), the ejected crown is closed to form a bubble and the transition boundary reveals a similar dependence on H as that for creation of a central jet.

  7. Hybrid pn-junction solar cells based on layers of inorganic nanocrystals and organic semiconductors: optimization of layer thickness by considering the width of the depletion region.

    PubMed

    Saha, Sudip K; Guchhait, Asim; Pal, Amlan J

    2014-03-01

    We report the formation and characterization of hybrid pn-junction solar cells based on a layer of copper diffused silver indium disulfide (AgInS2@Cu) nanoparticles and another layer of copper phthalocyanine (CuPc) molecules. With copper diffusion in the nanocrystals, their optical absorption and hence the activity of the hybrid pn-junction solar cells was extended towards the near-IR region. To decrease the particle-to-particle separation for improved carrier transport through the inorganic layer, we replaced the long-chain ligands of copper-diffused nanocrystals in each monolayer with short-ones. Under illumination, the hybrid pn-junctions yielded a higher short-circuit current as compared to the combined contribution of the Schottky junctions based on the components. A wider depletion region at the interface between the two active layers in the pn-junction device as compared to that of the Schottky junctions has been considered to analyze the results. Capacitance-voltage characteristics under a dark condition supported such a hypothesis. We also determined the width of the depletion region in the two layers separately so that a pn-junction could be formed with a tailored thickness of the two materials. Such a "fully-depleted" device resulted in an improved photovoltaic performance, primarily due to lessening of the internal resistance of the hybrid pn-junction solar cells. PMID:24452695

  8. Exploiting cellular convection in a thick liquid layer to pattern a thin polymer film

    NASA Astrophysics Data System (ADS)

    Nejati, Iman; Dietzel, Mathias; Hardt, Steffen

    2016-02-01

    A method to shape thin polymer films into periodic array of lenses is presented. A liquid layer placed on top of a much thinner polymer film is exposed to a transverse temperature gradient. The upper liquid layer undergoes the short-wavelength Bénard-Marangoni instability, which leads to periodic shear stresses at the liquid-liquid interface and corresponding interfacial deformations. The structures formed are solidified by curing with ultraviolet light. In comparison to previously reported single-layer patterning techniques, the presented method achieves structures of very high horizontal planform symmetry (highly ordered structures). Furthermore, other shapes of technical interest can be easily fabricated by engineering the temperature distribution at the liquid-gas interface.

  9. Thermodynamics and kinetic behaviors of thickness-dependent crystallization in high-k thin films deposited by atomic layer deposition

    SciTech Connect

    Nie, Xianglong; Ma, Fei; Ma, Dayan; Xu, Kewei

    2015-01-15

    Atomic layer deposition is adopted to prepare HfO{sub 2} and Al{sub 2}O{sub 3} high-k thin films. The HfO{sub 2} thin films are amorphous at the initial growth stage, but become crystallized when the film thickness (h) exceeds a critical value (h{sub critical}{sup *}). This phase transition from amorphous to crystalline is enhanced at higher temperatures and is discussed, taking into account the effect of kinetic energy. At lower temperatures, the amorphous state can be maintained even when h>h{sub critical}{sup *} owing to the small number of activated atoms. However, the number of activated atoms increases with the temperature, allowing crystallization to occur even in films with smaller thickness. The Al{sub 2}O{sub 3} thin films, on the other hand, maintain their amorphous state independent of the film thickness and temperature owing to the limited number of activated atoms. A thermodynamic model is proposed to describe the thickness-dependent phase transition.

  10. Quantification of Mixing of a Sonic Jet in Supersonic Crossflow due to Thick Turbulent Boundary Layer Interaction

    NASA Astrophysics Data System (ADS)

    Rossmann, Tobias; Pizzaia, Adam

    2013-11-01

    The upstream injection surface boundary layer is shown to have a significant effect on the mixing characteristics of a sonic jet in supersonic cross flow. A circular, high-pressure, sonic jet is injected into a M =3.5 supersonic crossflow through different boundary layer thickness (δ/D = 7.5 and 1), with variable injection angles (-20 to +20 degrees), and variable momentum ratios (J = 2, 5, and 10). Planar Laser Mie Scattering of condensed ethanol droplets is used to quantitatively image the injected fluid concentration in both the side and end views. Jet fluid concentrations PDFs are constructed to better understand the mixing dynamics. These PDFs are integrated to create mixed fluid fraction profiles that are then reduced to mixing efficiency. Mixing efficiency values are computed from different two-dimensional planes to determine if centerline mixing efficiencies are characteristic of the entire three-dimensional flow. Through these analyses, it is seen that thick boundary layers tend to marginally alter jet penetration and spread, but significantly worsen jet mixing capabilities, regardless of momentum ratio or injection angle.

  11. Comparison of the effect of cyanoacrylate- and polyurethane-based adhesives on a longitudinal strain solitary wave in layered polymethylmethacrylate waveguides

    NASA Astrophysics Data System (ADS)

    Dreiden, G. V.; Khusnutdinova, K. R.; Samsonov, A. M.; Semenova, I. V.

    2008-10-01

    We study the effect of two types of adhesive bonding on the propagation of a localized longitudinal strain wave in two- and three-layered elastic bars. The detectable variation in the decay rate of the wave at relatively long distances of propagation is observed. It is proposed that such variation can be used as an indicator of the type of an interface.

  12. Computational optimization and solution-processing of thick and efficient luminescent down-shifting layers for photovoltaics

    NASA Astrophysics Data System (ADS)

    Solodovnyk, Anastasiia; Kick, Christopher; Osvet, Andres; Egelhaaf, Hans-Joachim; Stern, Edda; Batentschuk, Miroslaw; Forberich, Karen; Brabec, Christoph J.

    2016-03-01

    Luminescent down-shifting (LDS) is a simple, powerful tool for increasing the range of solar irradiance that can be efficiently utilized by photovoltaic devices. We developed an optical model to simulate the ideal optical properties (absorbance, transmittance, luminescence quantum yield, etc.) of LDS layers for solar cells. We evaluated which quantum efficiencies and which optical densities are necessary to achieve an improvement in solar cell performance. In particular we considered copper indium gallium diselenide (CIGS) devices. Our model relies on experimentally measured data for the transmission and emission spectra as well as for the external quantum efficiency (EQE) of the solar cell. By combining experimental work with this optical model, we aim to propose an environmentally friendly technology for coating thick (300-500 μm), efficient luminescent down-shifting layers. These layers consist of polyvinyl butyral (PVB) and organic UV-converting fluorescent dyes. The absorption coefficients and luminescence quantum yields of the dyes were determined both in a solution of the solvent benzyl alcohol and in the solid polymer layers. This data shows that the dyes retain luminescence quantum yields of approximately 90% after solution-processing. The produced layers were then applied to CIGS solar cells, thereby improving the EQE of the devices in the UV region. At a wavelength of 390 nm, for instance, the EQE increased from 18% to 53%. These values closely agree with the theoretically calculated ones. The proposed technology, thus, provides a pathway toward efficient, fully solutionprocessable encapsulated photovoltaic modules.

  13. Evaluation of {11bar 22} Semipolar Multiple Quantum Wells Using Relaxed Thick InGaN Layers with Various In Compositions

    NASA Astrophysics Data System (ADS)

    Uchida, Katsumi; Miyoshi, Seita; Yamane, Keisuke; Okada, Narihito; Tadatomo, Kazuyuki; Kuwano, Noriyuki

    2013-08-01

    We have succeeded in the growth of a high-quality semipolar {11bar 22} GaN layer on an r-plane patterned sapphire substrate (r-PSS). In this study, we fabricated light-emitting diodes (LEDs) using relaxed thick InGaN layers with various In compositions. There were significant changes in polarization properties, indicating lattice mismatch reduction due to the use of a relaxed thick InGaN layer. Electroluminescence (EL) intensity was improved by using a relaxed thick InGaN layer with low In composition. In particular, the EL intensity improved approximately twofold compared with that in the case of LEDs without relaxed thick InGaN layers at an injection current of 200 mA.

  14. Channel layer thickness dependence of In-Ti-Zn-O thin-film transistors fabricated using pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Shan, F. K.; Liu, G. X.; Liu, A.; Lee, W. J.; Shin, B. C.

    2014-05-01

    Amorphous indium-titanium-zinc-oxide (ITZO) thin-film transistors (TFTs) with various channel thicknesses were fabricated at room temperature by using pulsed laser deposition. The channel layer thickness (CLT) dependence of the TFTs was investigated. All the ITZO thin films were amorphous, and the surface roughnesses decreased slightly first and then increased with increasing CLT. With increasing CLT from 35 to 140 nm, the on/off current ratio and the field-effect mobility increased, and the subthreshold swing decreased. The TFT with a CLT of 210 nm exhibited the worst performance, while the ITZO TFT with a CLT of 140 nm exhibited the best performance with a subthreshold voltage of 2.86 V, a mobility of 53.9 cm2V-1s-1, a subthreshold swing of 0.29 V/decade and an on/off current ratio of 109.

  15. In vitro corrosion of pure magnesium and AZ91 alloy-the influence of thin electrolyte layer thickness.

    PubMed

    Zeng, Rong-Chang; Qi, Wei-Chen; Zhang, Fen; Li, Shuo-Qi

    2016-03-01

    In vivo degradation predication faces a huge challenge via in vitro corrosion test due to the difficulty for mimicking the complicated microenvironment with various influencing factors. A thin electrolyte layer (TEL) cell for in vitro corrosion of pure magnesium and AZ91 alloy was presented to stimulate the in vivo corrosion in the micro-environment built by the interface of the implant and its neighboring tissue. The results demonstrated that the in vivo corrosion of pure Mg and the AZ91 alloy was suppressed under TEL condition. The AZ91 alloy was more sensitive than pure Mg to the inhibition of corrosion under a TEL thickness of less than 200 µm. The TEL thickness limited the distribution of current, and thus localized corrosion was more preferred to occur under TEL condition than in bulk solution. The TEL cell might be an appropriate approach to simulating the in vivo degradation of magnesium and its alloys. PMID:26816655

  16. Phase and thickness control of optical bistability and multistability in a defect slab with a single layer of graphene

    NASA Astrophysics Data System (ADS)

    Asadpour, Seyyed Hossein; Rahimpour Soleimani, H.

    2016-01-01

    In this letter, controllable optical bistability (OB) and optical multistability (OM) in a defect slab doped with a single-layer graphene nanostructure are proposed. Our numerical results show that it is easy to control OB by Rabi frequencies of coupling fields, detuning of coherent fields, and relative phase of applied fields. Moreover, the thickness effect of the slab is considered as a new parameter for controlling the OB behaviors. It is found that the transition from OB to OM or vice versa can be made possible by the thickness of the slab and relative phase of the applied fields. We hope that our results will have potential applications in quantum information science and technology based nanoscale devices.

  17. In vitro corrosion of pure magnesium and AZ91 alloy—the influence of thin electrolyte layer thickness

    PubMed Central

    Zeng, Rong-Chang; Qi, Wei-Chen; Zhang, Fen; Li, Shuo-Qi

    2016-01-01

    In vivo degradation predication faces a huge challenge via in vitro corrosion test due to the difficulty for mimicking the complicated microenvironment with various influencing factors. A thin electrolyte layer (TEL) cell for in vitro corrosion of pure magnesium and AZ91 alloy was presented to stimulate the in vivo corrosion in the micro-environment built by the interface of the implant and its neighboring tissue. The results demonstrated that the in vivo corrosion of pure Mg and the AZ91 alloy was suppressed under TEL condition. The AZ91 alloy was more sensitive than pure Mg to the inhibition of corrosion under a TEL thickness of less than 200 µm. The TEL thickness limited the distribution of current, and thus localized corrosion was more preferred to occur under TEL condition than in bulk solution. The TEL cell might be an appropriate approach to simulating the in vivo degradation of magnesium and its alloys. PMID:26816655

  18. Epitaxial growth and characterization of thick multi-layer 4H-SiC for very high-voltage insulated gate bipolar transistors

    NASA Astrophysics Data System (ADS)

    Miyazawa, Tetsuya; Nakayama, Koji; Tanaka, Atsushi; Asano, Katsunori; Ji, Shi-yang; Kojima, Kazutoshi; Ishida, Yuuki; Tsuchida, Hidekazu

    2015-08-01

    Techniques to fabricate thick multi-layer 4H-SiC epitaxial wafers were studied for very high-voltage p- and n-channel insulated gate bipolar transistors (IGBTs). Multi-layer epitaxial growth, including a thick p- drift layer (˜180 μm), was performed on a 4H-SiC n+ substrate to form a p-IGBT structure. For an n-IGBT structure, an inverted growth process was employed, in which a thick n- drift layer (˜180 μm) and a thick p++ injector layer (>55 μm) were epitaxially grown. The epitaxial growth conditions were modified to attain a low defect density, a low doping concentration, and a long carrier lifetime in the drift layers. Reduction of the forward voltage drop was attempted by using carrier lifetime enhancement processes, specifically, carbon ion implantation/annealing and thermal oxidation/annealing or hydrogen annealing. Simple PiN diodes were fabricated to demonstrate the effective conductivity modulation in the thick drift layers. The forward voltage drops of the PiN diodes with the p- and n-IGBT structures promise to obtain the extremely low-loss and very high-voltage IGBTs. The change in wafer shape during the processing of the very thick multi-layer 4H-SiC is also discussed.

  19. Geodynamo Models With a Thick Stable Layer and Heterogeneous CMB Heat Flow

    NASA Astrophysics Data System (ADS)

    Christensen, U. R.

    2015-12-01

    The upward revision of the thermal conductivity in the Earth's core makes it plausible that the mean heat flow at the core-mantle boundary (CMB) could be only afraction of what can be conducted down the core adiabat (perhaps one half). The upper part of the fluid core would be stably stratified to substantial depth. This is inconsistent with evidence for upwelling flow near the CMB from observations ofof magnetic flux expulsion. Heat flow at the CMB is likely very heterogeneous and would still be superadiabatic in some regions of the CMB. The dynamics of such a system is unclear. Gubbins et al. (Phys. Earth Planet. Int., in press, 2015)suggest that the locally unstable gradient would mix up the stable layer as a wholeand replace it by a weakly convecting one. We study dynamo models driven by a codensity flux from the inner core. On the outer boundary an inverse (on average) gradient is imposed, leading to stable stratification of the top 40% of the fluid shell. In addition to control cases with homogeneous CMB flux, we run models with two unstableregions centered on the equator. In the latter cases a predominantly horizontal circulation in a thin layer immediately below the outer boundary redistributes the heat that is conducted radially upward in the stable layer and transports ittowards the high heat-flow spots. Radial flow below these spots does not penetrate deeply into the stable layer, nor does the layer become mixed up to a significant degree. A dynamo operates in the convecting deep interior, however, its dipole moment is low in comparison to the Earth value. Heat flow heterogeneity at the CMB does not sem to solve the problems that exist for the geodynamo when the average heat flux is substantially subadiabatic.

  20. Preparation of a thick polymer brush layer composed of poly(2-methacryloyloxyethyl phosphorylcholine) by surface-initiated atom transfer radical polymerization and analysis of protein adsorption resistance.

    PubMed

    Inoue, Yuuki; Onodera, Yuya; Ishihara, Kazuhiko

    2016-05-01

    The purpose of this study was to prepare a thick polymer brush layer composed of poly(2-methacryloyloxyethyl phosphorylcholine (MPC)) and assess its resistance to protein adsorption from the dissolved state of poly(MPC) chains in an aqueous condition. The thick poly(MPC) brush layer was prepared through the surface-initiated atom transfer radical polymerization (SI-ATRP) of MPC with a free initiator from an initiator-immobilized substrate at given [Monomer]/[Free initiator] ratios. The ellipsometric thickness of the poly(MPC) brush layers could be controlled by the polymerization degree of the poly(MPC) chains. The thickness of the poly(MPC) brush layer in an aqueous medium was larger than that in air, and this tendency became clearer when the polymerization degree of the poly(MPC) increased. The maximum thickness of the poly(MPC) brush layer in an aqueous medium was around 110nm. The static air contact angle of the poly(MPC) brush layer in water indicated a reasonably hydrophilic nature, which was independent of the thickness of the poly(MPC) brush layer at the surface. This result occurred because the hydrated state of the poly(MPC) chains is not influenced by the environment surrounding them. Finally, as measured with a quartz crystal microbalance, the amount of protein adsorbed from a fetal bovine serum solution (10% in phosphate-buffered saline) on the original substrate was 420ng/cm(2). However, the poly(MPC) brush layer reduced this value dramatically to less than 50ng/cm(2). This effect was independent of the thickness of the poly(MPC) brush layer for thicknesses between 20nm and about 110nm. These results indicated that the surface covered with a poly(MPC) brush layer is a promising platform to avoid biofouling and could also be applied to analyze the reactions of biological molecules with a high signal/noise ratio. PMID:26896657

  1. Dispersion Relation in a Ferrofluid Layer of Any Thickness and Viscosity in a Normal Magnetic Field; Asymptotic Regimes

    NASA Astrophysics Data System (ADS)

    Abou, B.; Néron de Surgy, G.; Wesfreid, J. E.

    1997-08-01

    We have calculated the general dispersion relationship for surface waves on a ferrofluid layer of any thickness and viscosity, under the influence of a uniform vertical magnetic field. The amplification of these waves can induce an instability called peaks instability (Rosensweig instability). The expression of the dispersion relationship requires that the critical magnetic field and the critical wavenumber of the instability depend on the thickness of the ferrofluid layer. The dispersion relationship has been simplified into four asymptotic regimes: thick or thin layer and viscous or inertial behaviour. The corresponding critical values are presented. We show that a typical parameter of the ferrofluid enables one to know in which regime, viscous or inertial, the ferrofluid will be near the onset of instability. Nous avons calculé la relation de dispersion des ondes de surface dans une couche de ferrofluide d'épaisseur et de viscosité quelconques, soumise à un champ magnétique normal à sa surface (instabilité de pics de Rosensweig). Cette relation montre que le champ magnétique critique et le vecteur d'onde critique de l'instabilité dépendent de l'épaisseur de la couche de fluide. La relation de dispersion a été simplifiée pour quatre régimes asymptotiques: couche épaisse ou mince et comportement visqueux ou inertiel. Nous avons calculé les valeurs critiques de l'instabilité dans ces quatre cas. Nous montrons qu'un paramètre typique du ferrofluide permet de savoir dans quel régime, visqueux ou inertiel, se situe le ferrofluide près du seuil de l'instabilité.

  2. Sensitivity of ground motion parameters to local site effects for areas characterised by a thick buried low-velocity layer.

    NASA Astrophysics Data System (ADS)

    Farrugia, Daniela; Galea, Pauline; D'Amico, Sebastiano; Paolucci, Enrico

    2016-04-01

    It is well known that earthquake damage at a particular site depends on the source, the path that the waves travel through and the local geology. The latter is capable of amplifying and changing the frequency content of the incoming seismic waves. In regions of sparse or no strong ground motion records, like Malta (Central Mediterranean), ground motion simulations are used to obtain parameters for purposes of seismic design and analysis. As an input to ground motion simulations, amplification functions related to the shallow subsurface are required. Shear-wave velocity profiles of several sites on the Maltese islands were obtained using the Horizontal-to-Vertical Spectral Ratio (H/V), the Extended Spatial Auto-Correlation (ESAC) technique and the Genetic Algorithm. The sites chosen were all characterised by a layer of Blue Clay, which can be up to 75 m thick, underlying the Upper Coralline Limestone, a fossiliferous coarse grained limestone. This situation gives rise to a velocity inversion. Available borehole data generally extends down till the top of the Blue Clay layer therefore the only way to check the validity of the modelled shear-wave velocity profile is through the thickness of the topmost layer. Surface wave methods are characterised by uncertainties related to the measurements and the model used for interpretation. Moreover the inversion procedure is also highly non-unique. Such uncertainties are not commonly included in site response analysis. Yet, the propagation of uncertainties from the extracted dispersion curves to inversion solutions can lead to significant differences in the simulations (Boaga et al., 2011). In this study, a series of sensitivity analyses will be presented with the aim of better identifying those stratigraphic properties which can perturb the ground motion simulation results. The stochastic one-dimensional site response analysis algorithm, Extended Source Simulation (EXSIM; Motazedian and Atkinson, 2005), was used to perform

  3. The influence of matrix composition and ink layer thickness on iron gall ink determination by the PIXE method

    NASA Astrophysics Data System (ADS)

    Uršič, Mitja; Budnar, Miloš; Simčič, Jure; Pelicon, Primož

    2006-06-01

    The elemental composition of iron gall inks in historical documents can be effectively studied using the non-destructive proton induced X-ray emission (PIXE) method. The in-air proton beam experimental set-up installed at the Microanalytical Centre of the Jožef Stefan Institute was used for this purpose. The aim of the present investigation was to model and evaluate the uncertainties in the analysis due to the incompletely known matrix composition and iron gall ink layer thickness. Estimation of these uncertainties helped in quantifying the accuracy of multi-elemental PIXE analysis of historical documents.

  4. The impact of the layer thickness on the thermodynamic properties of pd hydride thin film electrodes.

    PubMed

    Vermeulen, Paul; Ledovskikh, Alexander; Danilov, Dmitry; Notten, Peter H L

    2006-10-19

    Recently, a lattice gas model was presented and successfully applied to simulate the absorption/desorption isotherms of various hydride-forming materials. The simulation results are expressed by parameters corresponding to several energy contributions, e.g., interaction energies. However, the use of a model system is indispensable in order to show the strength of the simulations. The palladium-hydrogen system is one of the most thoroughly described metal hydrides found in the literature and is therefore ideal for this purpose. The effects of decreasing the thickness of Pd thin films on the isotherms have been monitored experimentally and subsequently simulated. An excellent fit of the lattice gas model to the experimental data is found, and the corresponding parameters are used to describe several thermodynamic properties. It is analyzed that the contribution of H-H interaction energies to the total energy and the influence of the host lattice energy are significantly and systematically changing as a function of Pd thickness. Conclusively, it has been verified that the lattice gas model is a useful tool to analyze thermodynamic properties of hydrogen storage materials. PMID:17034217

  5. Coordinated Airborne, Spaceborne and Ground-based Measurements of Massive Thick Aerosol Layers during the Dry Season in Southern Africa

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Russell, P. B.; Hobbs, P. V.; Hlavka, D. L.; McGill, M. J.; Holben, B. N.; Welton, E. J.; Campbell, J. R.; Torres, O.

    2003-01-01

    During the dry season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), coordinated observations were made of massive thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sun photometer measurements of aerosol optical depth (lambda = 0.354- 1.557 microns), columnar water vapor, and vertical profiles of aerosol extinction and water vapor density that were obtained aboard the University of Washington's Convair-580 research aircraft. We compare these with ground-based AERONET Sun/sky radiometer results, with ground based lidar data (MPL-Net), and with measurements from a downward pointing lidar aboard the high-flying NASA ER-2 aircraft. Finally, we show comparisons between aerosol optical depths fiom the Sun photometer and those retrieved over land and over water using four spaceborne sensors (TOMS, MODIS, MISR, and ATSR-2).

  6. Coordinated Airborne, Spaceborne, and Ground-Based Measurements of Massive, Thick Aerosol Layers During the Dry Season in Southern Africa

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Russell, P. B.; Hobbs, P. V.; Hlavka, D. L.; McGill, M. J.; Holben, B. N.; Welton, E. J.; Campbell, J.; Torres, O.; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    During the dry-season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), unique coordinated observations were made of massive, thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sunphotometer measurements of aerosol optical depth (lambda=354-1558 nm), columnar water vapor, and vertical profiles of aerosol extinction and water vapor density that were obtained aboard the University of Washington's Convair-580 research aircraft. We compare these with ground-based AERONET Sun/sky radiometer results, with ground based lidar data MPL-Net), and with measurements from a downward-pointing lidar aboard the high-flying NASA ER-2 aircraft. Finally, we show comparisons between aerosol optical depths from the Sunphotometer and those retrieved over land and over water using four spaceborne sensors (TOMS (Total Ozone Mapping Spectrometer), MODIS (Moderate Resolution Imaging Spectrometer), MISR (Multiangle Imaging Spectroradiometer) and ATSR-2 (Along Track Scanning Radiometer)).

  7. nm- thick conformal pore-sealing of self-assembled mesoporous silica by plasma-assisted atomic layer deposition

    PubMed Central

    Jiang, Ying-Bing; Liu, Nanguo; Gerung, Henry; Cecchi, Joseph L.; Brinker, C. Jeffrey

    2009-01-01

    On a porous substrate, regular atomic layer deposition (ALD) not only takes place on top of the substrate but also penetrates into the internal porosity. Here we report a plasma-assisted process in which the ALD precursors are chosen to be non-reactive unless triggered by plasma, so that ALD can be spatially defined by the supply of plasma irradiation. Since plasma cannot penetrate within the internal porosity, ALD has been successfully confined to the immediate surface. This not only gives a possible solution for sealing of porous low dielectric constant films with a conformal layer of nm-scale thickness, but also enables us to progressively reduce the pore size of mesoporous materials in a sub-Å/cycle fashion for membrane formation. PMID:16925407

  8. Effect of antiferromagnetic layer thickness on exchange bias, training effect, and magnetotransport properties in ferromagnetic/antiferromagnetic antidot arrays

    SciTech Connect

    Gong, W. J.; Liu, W. Feng, J. N.; Zhang, Z. D.; Kim, D. S.; Choi, C. J.

    2014-04-07

    The effect of antiferromagnetic (AFM) layer on exchange bias (EB), training effect, and magnetotransport properties in ferromagnetic (FM) /AFM nanoscale antidot arrays and sheet films Ag(10 nm)/Co(8 nm)/NiO(t{sub NiO})/Ag(5 nm) at 10 K is studied. The AFM layer thickness dependence of the EB field shows a peak at t{sub NiO} = 2 nm that is explained by using the random field model. The misalignment of magnetic moments in the three-dimensional antidot arrays causes smaller decrease of EB field compared with that in the sheet films for training effect. The anomalous magnetotransport properties, in particular positive magnetoresistance (MR) for antidot arrays but negative MR for sheet films are found. The training effect and magnetotransport properties are strongly affected by the three-dimensional spin-alignment effects in the antidot arrays.

  9. Mapping bound plasmon propagation on a nanoscale stripe waveguide using quantum dots: influence of spacer layer thickness.

    PubMed

    Perera, Chamanei S; Funston, Alison M; Cheng, Han-Hao; Vernon, Kristy C

    2015-01-01

    In this paper we image the highly confined long range plasmons of a nanoscale metal stripe waveguide using quantum emitters. Plasmons were excited using a highly focused 633 nm laser beam and a specially designed grating structure to provide stronger incoupling to the desired mode. A homogeneous thin layer of quantum dots was used to image the near field intensity of the propagating plasmons on the waveguide. We observed that the photoluminescence is quenched when the QD to metal surface distance is less than 10 nm. The optimised spacer layer thickness for the stripe waveguides was found to be around 20 nm. Authors believe that the findings of this paper prove beneficial for the development of plasmonic devices utilising stripe waveguides. PMID:26665075

  10. Impedance analysis of nano thickness layered AlGaN acoustic sensor deposited by thermionic vacuum arc

    NASA Astrophysics Data System (ADS)

    Özen, Soner; Bilgiç, Eyüp; Gülmez, Gülay; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan; Mohammadigharehbagh, Reza

    2016-03-01

    In this study, AlGaN acoustic sensor was deposited on aluminum metal substrate by thermionic vacuum arc (TVA) method for the first time. Gallium materials are used in many applications for optoelectronic device and semiconductor technology. Thermionic vacuum arc is the deposition technology for the variously materials and applications field. The thickness of the acoustic sensor is in deposited as nano layer. Impedance analyses were realized. Also, TVA production parameters and some properties of the deposited layers were investigated. TVA is a fast deposition technology for the gallium compounds and doped gallium compounds. Obtained results show that AlGaN materials are very promising materials. Moreover, these acoustic sensors have been produced by TVA technology.

  11. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multifrequency EM

    NASA Astrophysics Data System (ADS)

    Hoppmann, Mario; Hunkeler, Priska A.; Hendricks, Stefan; Kalscheuer, Thomas; Gerdes, Rüdiger

    2016-04-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise, accumulate beneath nearby sea ice, and subsequently form a several meter thick, porous sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator of the health of an ice shelf. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions within the platelet layer using Archie's Law. The thickness results agreed well with drillhole validation datasets within the uncertainty range, and the ice-volume fraction yielded results comparable to other studies. Both parameters together enable an estimation of the total ice volume within the platelet layer, which was found to be comparable to the volume of landfast sea ice in this region, and corresponded to more than a quarter of the annual basal melt volume of the nearby Ekström Ice Shelf. Our findings show that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties, with important implications for research into ocean/ice-shelf/sea-ice interactions. However, a successful application of this

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

    PubMed

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

    2015-12-15

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

  13. Magnetic properties and microstructure of Sm-Co/α-Fe nanocomposite thick film-magnets composed of multi-layers over 700 layers

    SciTech Connect

    Tou, A. Morimura, T.; Nakano, M.; Yamai, T.; Fukunaga, H.

    2014-05-07

    We synthesized Sm-Co/α-Fe nanocomposite film-magnets, approximately 10 μm in thickness, composed of 780 layers by the pulse laser deposition method. Transmission electron microscopic observations revealed that the synthesized film is composed of Sm-Co and α-Fe layers with the well-controlled α-Fe thickness of approximately 10–20 nm, which is suitable one predicted by the micromagnetic simulation. In spite of the enhanced interlayer diffusion of Fe and Co by annealing for crystallization, the (BH){sub max} value of 100 kJ/m{sup 3} was obtained at the averaged compositions of Sm/(Sm + Co) = 0.16 and Fe/(Sm + Co + Fe) = 0.47. The α-Fe fraction for obtaining the highest (BH){sub max} value was smaller than that expected from the micromagnetic simulation. Although the annealing for crystallization lay the easy direction of magnetization in the plane, the film is not expected to have strong crystallographic texture.

  14. Measure Guideline: Incorporating Thick Layers of Exterior Rigid Insulation on Walls

    SciTech Connect

    Lstiburek, Joseph; Baker, Peter

    2015-04-01

    This measure guideline provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ inches and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: fundamental building science principles relating to the use of exterior insulation on wall assemblies; design principles for tailoring this use to the specific project goals and requirements; and construction detailing to increase understanding about implementing the various design elements.

  15. Measure Guideline. Incorporating Thick Layers of Exterior Rigid Insulation on Walls

    SciTech Connect

    Lstiburek, Joseph; Baker, Peter

    2015-04-09

    This measure guideline, written by the U.S. Department of Energy’s Building America team Building Science Corporation, provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ in. and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: (1) fundamental building science principles relating to the use of exterior insulation on wall assemblies; (2) design principles for tailoring this use to the specific project goals and requirements; and (3) construction detailing to increase understanding about implementing the various design elements.

  16. Performance Dependences of Multiplication Layer Thickness for InP/InGaAs Avalanche Photodiodes Based on Time Domain Modeling

    NASA Technical Reports Server (NTRS)

    Xiao, Yegao; Bhat, Ishwara; Abedin, M. Nurul

    2005-01-01

    InP/InGaAs avalanche photodiodes (APDs) are being widely utilized in optical receivers for modern long haul and high bit-rate optical fiber communication systems. The separate absorption, grading, charge, and multiplication (SAGCM) structure is an important design consideration for APDs with high performance characteristics. Time domain modeling techniques have been previously developed to provide better understanding and optimize design issues by saving time and cost for the APD research and development. In this work, performance dependences on multiplication layer thickness have been investigated by time domain modeling. These performance characteristics include breakdown field and breakdown voltage, multiplication gain, excess noise factor, frequency response and bandwidth etc. The simulations are performed versus various multiplication layer thicknesses with certain fixed values for the areal charge sheet density whereas the values for the other structure and material parameters are kept unchanged. The frequency response is obtained from the impulse response by fast Fourier transformation. The modeling results are presented and discussed, and design considerations, especially for high speed operation at 10 Gbit/s, are further analyzed.

  17. Growth of thick, continuous GaN layers on 4-in. Si substrates by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Schenk, H. P. D.; Frayssinet, E.; Bavard, A.; Rondi, D.; Cordier, Y.; Kennard, M.

    2011-01-01

    We report on the growth of thick GaN epilayers on 4-in. Si(1 1 1) substrates by metalorganic chemical vapor deposition. Using intercalated AlN layers that contribute to counterbalance the tensile strain induced by the thermal mismatch between gallium nitride and the silicon substrate, up to 6.7 μm thick crack-free group III-nitride layers have been grown. Root mean-squares surface roughness of 0.5 nm, threading dislocation densities of 1.1×10 9 cm -2, as well as X-ray diffraction (XRD) full widths at half-maximum (FWHM) of 406 arcsec for the GaN(0 0 2) and of 1148 arcsec for the GaN(3 0 2) reflection have been measured. The donor bound exciton has a low-temperature photoluminescence line width of 12 meV. The correlation between the threading dislocation density and XRD FWHM, as well as the correlation between the wafer curvature and the GaN in-plane stress is discussed. An increase of the tensile stress is observed upon n-type doping of GaN by silicon.

  18. Direct e-beam writing of dense and high aspect ratio nanostructures in thick layers of PMMA for electroplating

    NASA Astrophysics Data System (ADS)

    Gorelick, Sergey; Guzenko, Vitaliy A.; Vila-Comamala, Joan; David, Christian

    2010-07-01

    Due to the ability of 100 keV electrons to penetrate deep into resist with little scattering, we were able to directly write various dense and high aspect ratio nanostructures in 540 nm and 1.1 µm thick layers of poly(methyl methacrylate) (PMMA) resist. The PMMA molds produced by electron beam lithography were developed using a high contrast developer. The molds were used to transfer the pattern into metallic nanostructures by filling the developed trenches with Au by electroplating. By exposing lines narrower than the target width, we observed improved process latitude and line width control. The obtained aspect ratios of the dense structures are nearly 20 in 1.1 µm PMMA layers and > 16 for structures electroplated into this PMMA mold. The fabrication method was successfully applied to produce Au diffractive x-ray Fresnel zone plates of exceptionally good quality with 50 and 70 nm outermost zones using 540 nm and 1.1 µm thick PMMA molds. In addition, we also produced regular arrays of high aspect ratio and dense Au nanorods with periods down to 100 nm and high aspect ratio split-ring resonators.

  19. Direct e-beam writing of dense and high aspect ratio nanostructures in thick layers of PMMA for electroplating.

    PubMed

    Gorelick, Sergey; Guzenko, Vitaliy A; Vila-Comamala, Joan; David, Christian

    2010-07-23

    Due to the ability of 100 keV electrons to penetrate deep into resist with little scattering, we were able to directly write various dense and high aspect ratio nanostructures in 540 nm and 1.1 microm thick layers of poly(methyl methacrylate) (PMMA) resist. The PMMA molds produced by electron beam lithography were developed using a high contrast developer. The molds were used to transfer the pattern into metallic nanostructures by filling the developed trenches with Au by electroplating. By exposing lines narrower than the target width, we observed improved process latitude and line width control. The obtained aspect ratios of the dense structures are nearly 20 in 1.1 microm PMMA layers and > 16 for structures electroplated into this PMMA mold. The fabrication method was successfully applied to produce Au diffractive x-ray Fresnel zone plates of exceptionally good quality with 50 and 70 nm outermost zones using 540 nm and 1.1 microm thick PMMA molds. In addition, we also produced regular arrays of high aspect ratio and dense Au nanorods with periods down to 100 nm and high aspect ratio split-ring resonators. PMID:20601756

  20. Association between retinal nerve fiber layer thickness and magnetic resonance imaging findings and intelligence in patients with multiple sclerosis

    PubMed Central

    Ashtari, Fereshteh; Emami, Parisa; Akbari, Mojtaba

    2015-01-01

    Background: Multiple Sclerosis (MS) is a neurological disease in which demyelination and axonal loss leads to progressive disability. Cognition impairment is among the most common complication. Studying axonal loss in the retina is a new marker for MS. The main goal of our study is to search for correlations between magnetic resonance imaging (MRI) findings and the retinal nerve fiber layer (RNFL) thickness at the macula and head of the optic nerve and Wechsler Adult Intelligence Scale-Revised (WAIS-R) Scores that assess multiple domains of intelligence, and to explore the relationship between changes in the RNFL thickness with intellectual and cognitive dysfunction. Materials and Methods: A prospective cross-sectional study was conducted at the University Hospital of Kashani, Isfahan, Iran, from September to December 2013. All patients were assessed with a full-scale intelligence quotient (IQ) on the WAIS-R. An optical coherence tomography study and brain MRI were performed in the same week for all the patients. Statistical analysis was conducted by using a bivariate correlation, by utilizing SPSS 20.0. A P value ≤ 0.05 was the threshold of statistical significance. Results: Examination of a 100 patients showed a significant correlation between the average RNFL thickness of the macula and the verbal IQ (P value = 0.01) and full IQ (P value = 0.01). There was a significant correlation between brain atrophy and verbal IQ. Conclusion: The RNFL loss was correlated with verbal IQ and full IQ. PMID:26682201

  1. Changes in Peripapillary Retinal Nerve Fiber Layer Thickness after Pattern Scanning Laser Photocoagulation in Patients with Diabetic Retinopathy

    PubMed Central

    Park, Yi-Ryeung

    2014-01-01

    Purpose To examine the effects of panretinal photocoagulation (PRP) using a pattern scanning laser (PASCAL) system on the retinal nerve fiber layer (RNFL) thickness in patients with diabetic retinopathy. Methods This retrospective study included 105 eyes with diabetic retinopathy, which consisted of three groups: the PASCAL group that underwent PRP with the PASCAL method (33 eyes), the conventional group that underwent conventional PRP treatment (34 eyes), and the control group that did not receive PRP (38 eyes). The peripapillary RNFL thickness was measured by optical coherence tomography before, six months, and one year after PRP to evaluate the changes in peripapillary RNFL. Results The RNFL thickness in the PASCAL group did not show a significant difference after six months (average 3.7 times, p = 0.15) or one year after the PRP (average 3.7 times, p = 0.086), whereas that in the conventional group decreased significantly after six months (average 3.4 times, p < 0.001) and one year after PRP (average 3.4 times, p < 0.001). Conclusions The results of this study suggest that the PASCAL system may protect against RNFL loss by using less energy than conventional PRP. PMID:24882955

  2. Study of Retinal Nerve Fibre Layer Thickness in Patients with Diabetes Mellitus Using Fourier Domain Optical Coherence Tomography

    PubMed Central

    Sah, Sonal; Gupta, Neeti

    2016-01-01

    Introduction Diabetic retina undergoes degenerative changes in retinal nerve fiber layer (RNFL) in addition to vascular changes. Loss of RNFL with changes in inner retina and their association with metabolic control have been studied with varied results in diabetic patients. Aim To compare the RNFL thickness between diabetic patients and age matched healthy controls and to correlate the thickness to metabolic control. Materials and Methods One hundred and sixty five patients were enrolled in the study out of which 50 served as controls, 58 patients were diabetic without retinopathy and 57 patients had diabetic retinopathy. Both eyes of all patients underwent optical coherence tomography scans for RNFL and ganglion cell complex. Foveal and parafoveal thickness were also measured. All the parameters were compared to patient’s metabolic control. Results RNFL thinning was observed in superotemporal (p-value = 0.001) and upper nasal sectors (p-value = 0.031) around the optic disc in eyes with diabetic retinopathy. Ganglion cell complex also showed statistically significant thinning in diabetic patients. Creatinine levels showed a weak negative correlation to the RNFL. Conclusion This study positively concluded that neurodegeneration in an early component of diabetic retinopathy.

  3. Helicobacter pylori in vivo causes structural changes in the adherent gastric mucus layer but barrier thickness is not compromised

    PubMed Central

    Newton, J; Jordan, N; Oliver, L; Strugala, V; Pearson, J; James, O; Allen, A

    1998-01-01

    Background—It has been proposed that a pathogenic effect of Helicobacter pylori is a weakening of the protective mucus barrier; however, this remains controversial. 
Aims—To clarify the effects of H pylori infection on the mucus gel barrier in vivo. 
Methods—Mucus gel polymeric structure and the thickness of the adherent mucus barrier were measured in endoscopic biopsy samples in subjects with and without H pylori infection. 
Results—There was a significant 18% reduction in the proportion of polymeric gel forming mucin in the adherent mucus layer in H pylori positive compared with negative subjects. There was no change in the adherent mucus thickness between H pylori positive and negative subjects without gastric atrophy (mean (SD): 104(26) µm, 106 (30) µm respectively). There was however a significant reduction in mucus thickness in those H pylori positive subjects with underlying gastric atrophy (84 (13) µm, p=0.03) compared with those without atrophy. 
Conclusions—A partial breakdown in gel forming structure of the gastric mucus barrier does occur in H pylori infection per se but this is insufficient to cause a collapse of the mucus barrier. 

 Keywords: Helicobacter pylori; gastric mucus PMID:9824571

  4. Central Glaucomatous Damage of the Macula Can Be Overlooked by Conventional OCT Retinal Nerve Fiber Layer Thickness Analyses

    PubMed Central

    Wang, Diane L.; Raza, Ali S.; de Moraes, Carlos Gustavo; Chen, Monica; Alhadeff, Paula; Jarukatsetphorn, Ravivarn; Ritch, Robert; Hood, Donald C.

    2015-01-01

    Purpose To assess the extent to which glaucomatous damage of the macula can be detected using the summary statistics of a commercial report based upon the circumpapillary retinal nerve fiber layer (cpRNFL) thickness obtained with frequency domain optical coherence tomography (fdOCT). Methods One hundred forty-three eyes of 143 open-angle glaucoma patients and suspects (56.4 ± 13.8 years) had 10-2 visual fields (VFs) and fdOCT macular and disc cube scans. RNFL and retinal ganglion cell plus inner plexiform layer thickness and probability maps were generated and combined with 10-2 VF information in a single-page, custom report previously described. Three graders evaluated these reports and classified each eye as “abnormal macula” or “normal macula.” Commercially available fdOCT reports for cpRNFL thickness were generated using the automatic segmentation algorithm and norms from the machine. The ability of the reports to detect macular damage was analyzed in three ways: temporal quadrant (TQ) < 5%; TQ < 5% or clock hour 7 < 1% (TQ + CH7); and clock hours 7 through 10 with two sectors < 5% or one sector < 1% (CH7−10). Results Sixty-one (43%) eyes were classified “abnormal macula” and 41 (29%) as “normal macula”; the 10-2 VFs and OCT probability maps did not agree in the remaining eyes. Of the 61 abnormal eyes, the TQ criterion missed 47 (77%); TQ + CH7 missed 24 (39%); and CH7−10 missed 22 (36%). Conclusions Conventional cpRNFL analyses on commercial OCT reports can miss macular (central field) damage. Translational Relevance To detect glaucomatous damage of the macula, additional tests, such as macular cube scans and/or 10-2 VFs, should be performed. PMID:26644964

  5. Satellite retrieved cloud optical thickness sensitive to surface wind speed in the subarctic marine boundary layer

    NASA Astrophysics Data System (ADS)

    Glantz, Paul

    2010-07-01

    The optical and microphysical properties of low level marine clouds, presented over the Norwegian Sea and Barents Sea, have been investigated for the period 2000-2006. The air masses were transported for more or less seven days over the warmer North Atlantic before they arrived at the area investigated. The main focus in this study is on investigating the relationship between cloud optical thickness (COT) and surface wind speed (U10 m) using satellite retrievals in combination with operational meteorological data. A relatively strong correlation (R2 = 0.97) is obtained for wind speeds up to 12 m s - 1, in air masses that were probably to a major degree influenced by wind shears and to a minor degree by buoyancy. The relationship (U2.5) is also in between those most commonly found in the literature for water vapor (~U1) and sea salt (~U3.4). The present results highlight the magnitude of marine sea-spray influence on COT and their global climatic importance.

  6. Bottom-gate coplanar graphene transistors with enhanced graphene adhesion on atomic layer deposition Al2O3

    NASA Astrophysics Data System (ADS)

    Park, Dong-Wook; Mikael, Solomon; Chang, Tzu-Hsuan; Gong, Shaoqin; Ma, Zhenqiang

    2015-03-01

    A graphene transistor with a bottom-gate coplanar structure and an atomic layer deposition (ALD) aluminum oxide (Al2O3) gate dielectric is demonstrated. Wetting properties of ALD Al2O3 under different deposition conditions are investigated by measuring the surface contact angle. It is observed that the relatively hydrophobic surface is suitable for adhesion between graphene and ALD Al2O3. To achieve hydrophobic surface of ALD Al2O3, a methyl group (CH3)-terminated deposition method has been developed and compared with a hydroxyl group (OH)-terminated deposition. Based on this approach, bottom-gate coplanar graphene field-effect transistors are fabricated and characterized. A post-thermal annealing process improves the performance of the transistors by enhancing the contacts between the source/drain metal and graphene. The fabricated transistor shows an Ion/Ioff ratio, maximum transconductance, and field-effect mobility of 4.04, 20.1 μS at VD = 0.1 V, and 249.5 cm2/V.s, respectively.

  7. Value of corneal epithelial and Bowman’s layer vertical thickness profiles generated by UHR-OCT for sub-clinical keratoconus diagnosis

    PubMed Central

    Xu, Zhe; Jiang, Jun; Yang, Chun; Huang, Shenghai; Peng, Mei; Li, Weibo; Cui, Lele; Wang, Jianhua; Lu, Fan; Shen, Meixiao

    2016-01-01

    Ultra-high resolution optical coherence tomography (UHR-OCT) can image the corneal epithelium and Bowman’s layer and measurement the thicknesses. The purpose of this study was to validate the diagnostic power of vertical thickness profiles of the corneal epithelium and Bowman’s layer imaged by UHR-OCT in the diagnosis of sub-clinical keratoconus (KC). Each eye of 37 KC patients, asymptomatic fellow eyes of 32 KC patients, and each eye of 81 normal subjects were enrolled. Vertical thickness profiles of the corneal epithelium and Bowman’s layer were measured by UHR-OCT. Diagnostic indices were calculated from vertical thickness profiles of each layer and output values of discriminant functions based on individual indices. Receiver operating characteristic curves were determined, and the accuracy of the diagnostic indices were assessed as the area under the curves (AUC). Among all of the individual indices, the maximum ectasia index for epithelium had the highest ability to discriminate sub-clinical KC from normal corneas (AUC = 0.939). The discriminant function containing maximum ectasia indices of epithelium and Bowman’s layer further increased the AUC value (AUC = 0.970) for sub-clinical KC diagnosis. UHR-OCT-derived thickness indices from the entire vertical thickness profiles of the corneal epithelium and Bowman’s layer can provide valuable diagnostic references to detect sub-clinical KC. PMID:27511620

  8. Value of corneal epithelial and Bowman's layer vertical thickness profiles generated by UHR-OCT for sub-clinical keratoconus diagnosis.

    PubMed

    Xu, Zhe; Jiang, Jun; Yang, Chun; Huang, Shenghai; Peng, Mei; Li, Weibo; Cui, Lele; Wang, Jianhua; Lu, Fan; Shen, Meixiao

    2016-01-01

    Ultra-high resolution optical coherence tomography (UHR-OCT) can image the corneal epithelium and Bowman's layer and measurement the thicknesses. The purpose of this study was to validate the diagnostic power of vertical thickness profiles of the corneal epithelium and Bowman's layer imaged by UHR-OCT in the diagnosis of sub-clinical keratoconus (KC). Each eye of 37 KC patients, asymptomatic fellow eyes of 32 KC patients, and each eye of 81 normal subjects were enrolled. Vertical thickness profiles of the corneal epithelium and Bowman's layer were measured by UHR-OCT. Diagnostic indices were calculated from vertical thickness profiles of each layer and output values of discriminant functions based on individual indices. Receiver operating characteristic curves were determined, and the accuracy of the diagnostic indices were assessed as the area under the curves (AUC). Among all of the individual indices, the maximum ectasia index for epithelium had the highest ability to discriminate sub-clinical KC from normal corneas (AUC = 0.939). The discriminant function containing maximum ectasia indices of epithelium and Bowman's layer further increased the AUC value (AUC = 0.970) for sub-clinical KC diagnosis. UHR-OCT-derived thickness indices from the entire vertical thickness profiles of the corneal epithelium and Bowman's layer can provide valuable diagnostic references to detect sub-clinical KC. PMID:27511620

  9. Low frequency EC-GMR detection of cracks at ferromagnetic fastener sites in thick layered structure

    NASA Astrophysics Data System (ADS)

    Yang, G.; Tamburrino, A.; Zeng, Z.; Deng, Y.; Liu, X.,; Udpa, L.; Udpa, S. S.

    2013-01-01

    The detection of embedded cracks under fastener heads (CUF) in multilayer structures is a major challenge facing the aviation industry. Eddy current (EC) based techniques, such as Magneto-Optic Imager, Sliding probe and Self-nulling EC probes, and low frequency EC methods have been investigated. The prior work of authors presented an EC system using a uniform field excitation combined with giant magnetoresistive (GMR) sensors for imaging the normal component of magnetic flux density, has improved the effectiveness in detecting 2nd and 3rd layer CUFs with aluminum fasteners. However, detection of CUFs with ferromagnetic fasteners remains a major challenge. This paper presents the experimental study of automatic crack detection under steel fastener sites using low frequency EC with 3D GMR sensors that measure all 3 components of the induced magnetic flux density. A finite element model based study is used to optimize the system design and the experimental validation is presented.

  10. Mechanistic study of the rubber-brass adhesion interphase

    NASA Astrophysics Data System (ADS)

    Ashirgade, Akshay

    Brass-plated steel tire cords form an essential strengthening component of a radial automobile tire. Adhesion between rubber compound and brass-plated steel tire cord is crucial in governing the overall performance of tires. The rubber-brass interfacial adhesion is influenced by the chemical composition and thickness of the interfacial layer. It has been shown that the interfacial layer consists mainly of sulfides and oxides of copper and zinc. This thesis discusses the effect of changes in the chemical composition and the structure of the interfacial layers due to addition of adhesion promoter resins. Grazing incidence X-Ray Diffraction (GIXRD) experiments were run on sulfidized polished brass coupons previously bonded to six experimental rubber compounds. It was confirmed that heat and humidity conditions lead to physical and chemical changes of the rubber-steel tire cord interfacial layer, closely related to the degree of rubber-brass adhesion. Morphological transformation of the interfacial layer led to loss of adhesion after aging. The adhesion promoter resins inhibit unfavorable morphological changes in the interfacial layer thus stabilizing it during aging and prolonging failure. Tire cord adhesion tests illustrated that the one-component resins improved adhesion after aging using a rubber compound with lower cobalt loading. Based on the acquired diffraction profiles, these resins were also found to impede crystallization of the sulfide layer after aging leading to improved adhesion. Secondary Ion Mass Spectrometry (SIMS) depth profiles, SEM micrographs and AFM images strongly corroborated the findings from GIXRD. FTIR was utilized in a novel way to understand the degradation mechanism due to aging. A model for rubber and interfacial layer degradation is proposed to illustrate the effect of aging and the one-component resins. This interfacial analysis adds valuable new information to our understanding of the complex nature of the rubber-brass bonding

  11. Interlayer electronic hybridization leads to exceptional thickness-dependent vibrational properties in few-layer black phosphorus.

    PubMed

    Hu, Zhi-Xin; Kong, Xianghua; Qiao, Jingsi; Normand, Bruce; Ji, Wei

    2016-02-01

    Stacking two-dimensional (2D) materials into multi-layers or heterostructures, known as van der Waals (vdW) epitaxy, is an essential degree of freedom for tuning their properties on demand. Few-layer black phosphorus (FLBP), a material with high potential for nano- and optoelectronics applications, appears to have interlayer couplings much stronger than graphene and other 2D systems. Indeed, these couplings call into question whether the stacking of FLBP can be governed only by vdW interactions, which is of crucial importance for epitaxy and property refinement. Here, we perform a theoretical investigation of the vibrational properties of FLBP, which reflect directly its interlayer coupling, by discussing six Raman-observable phonons, including three optical, one breathing and two shear modes. With increasing sample thickness, we find anomalous redshifts of the frequencies for each optical mode but a blueshift for the armchair shear mode. Our calculations also show splitting of the phonon branches, due to anomalous surface phenomena, and strong phonon-phonon coupling. By computing uniaxial stress effects, inter-atomic force constants and electron densities, we provide a compelling demonstration that these properties are the consequence of strong and highly directional interlayer interactions arising from the electronic hybridization of the lone electron-pairs of FLBP, rather than from vdW interactions. This exceptional interlayer coupling mechanism controls the stacking stability of BP layers and thus opens a new avenue beyond vdW epitaxy for understanding the design of 2D heterostructures. PMID:26763557

  12. High Resolution 2-D Fluoresd3nce Imaging of the Mass Boundary Layer Thickness at Free Water Surfaces

    NASA Astrophysics Data System (ADS)

    Kräuter, C.; Trofimova, D.; Kiefhaber, D.; Krah, N.; Jähne, B.

    2014-03-01

    A novel 2-D fluorescence imaging technique has been developed to visualize the thickness of the aqueous mass boundary layer at a free water surface. Fluorescence is stimulated by high-power LEDs and is observed from above with a low noise, high resolution and high-speed camera. The invasion of ammonia into water leads to an increase in pH (from a starting value of 4), which is visualized with the fluorescent dye pyranine. The flux of ammonia can be controlled by controlling its air side concentration. A higher flux leads to basic pH values (pH > 7) in a thicker layer at the water surface from which fluorescent light is emitted. This allows the investigation of processes affecting the transport of gases in different depths in the aqueous mass boundary layer. In this paper, the chemical system and optical components of the measurement method are presented and its applicability to a wind-wave tank experiment is demonstrated.

  13. Active layer thickness and thaw subsidence in permafrost terrain: results from long-term observations near Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Shiklomanov, N. I.; Streletskiy, D. A.; Nelson, F. E.

    2012-12-01

    Patterns of active-layer thickness (ALT) on the North Slope of Alaska are highly variable, both spatially and temporally. Although geographic patterns of ALT repeat themselves from year to year, ALT is an integrated response to a large number of parameters. Thaw penetration into an ice-rich layer at the base of the active layer is accompanied by loss of volume (thaw consolidation) and results in subsidence at the ground surface. Differential thaw settlement occurs annually in permafrost environments as the layer of annual thaw (the active layer) develops. Significant ice segregation can occur at the bottom of the active layer during "cold" periods, due predominantly to freezing from below in the autumn and winter. This study examines trends in seasonal thawing of soils and vertical movements of the ground surface associated with formation and ablation of ice near the permafrost table in the Barrow region. The core thaw depth data set consists of ALT measurements conducted under the Circumpolar Active Layer Monitoring (CALM) program. The Barrow CALM site, represented by a regular 1 km2 grid, was established in the early 1990s. The reported ALT observations were initiated in 1992 and are measured annually in late August. Additional ALT measurements are available from a series of 10 x 10 meter plots established in 1962 as part of the Cold Regions Research and Engineering Laboratory (CRREL) research program at Barrow. Annual observations were made between 1962 and 1970. Measurements were reestablished in 1991 under the CALM program, following the original methodology. Field investigations to track interannual vertical movements associated with formation and ablation of ice near the permafrost table were initiated in 2003. Measurements continue annually at several CRREL plots representative of different elements of the tundra landscape. Observations were made at the end of the thawing season using Differential Global Positioning Systems (DGPS) technology. Results from

  14. Effects of AlN buffer layer thickness on the crystallinity and surface morphology of 10-µm-thick a-plane AlN films grown on r-plane sapphire substrates

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Hung; Tamaki, Shinya; Yamashita, Yasuhiro; Miyake, Hideto; Hiramatsu, Kazumasa

    2016-08-01

    10-µm-thick a-plane AlN(11\\bar{2}0) films containing a low-temperature AlN (LT-AlN) buffer layer and a high-temperature AlN (HT-AlN) film were prepared on r-plane sapphire (1\\bar{1}02) substrates. The crystallinity of all the samples with different LT-AlN buffer layer thicknesses was improved after thermal annealing and HT-AlN growth, mainly owing to the elimination of domain boundaries and the concurrent suppression of facet formation. The optimum crystallinity of HT-AlN films was obtained with full widths at half maximum of the X-ray rocking curves of 660 arcsec for AlN(11\\bar{2}0)\\parallel [1\\bar{1}00]AlN and 840 arcsec for (0002) using a 200-nm-thick LT-AlN buffer layer.

  15. Stanene: Atomically Thick Free-standing Layer of 2D Hexagonal Tin.

    PubMed

    Saxena, Sumit; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    Stanene is one of most important of 2D materials due to its potential to demonstrate room temperature topological effects due to opening of spin-orbit gap. In this pursuit we report synthesis and investigation of optical properties of stanene up to few layers, a two-dimensional hexagonal structural analogue of graphene. Atomic scale morphological and elemental characterization using HRTEM equipped with SAED and EDAX detectors confirm the presence of hexagonal lattice of Sn atoms. The position of Raman peak along with the inter-planar 'd' spacing obtained from SAED for prepared samples are in good agreement with that obtained from first principles calculations and confirm that the sheets are not (111) α-Sn sheets. Further, the optical signature calculated using density functional theory at ~191 nm and ~233 nm for low buckled stanene are in qualitative agreement with the measured UV-Vis absorption spectrum. AFM measurements suggest interlayer spacing of ~0.33 nm in good agreement with that reported for epitaxial stanene sheets. No traces of oxygen were observed in the EDAX spectrum suggesting the absence of any oxidized phases. This is also confirmed by Raman measurements by comparing with oxidized stanene sheets. PMID:27492139

  16. Stanene: Atomically Thick Free-standing Layer of 2D Hexagonal Tin

    PubMed Central

    Saxena, Sumit; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    Stanene is one of most important of 2D materials due to its potential to demonstrate room temperature topological effects due to opening of spin-orbit gap. In this pursuit we report synthesis and investigation of optical properties of stanene up to few layers, a two-dimensional hexagonal structural analogue of graphene. Atomic scale morphological and elemental characterization using HRTEM equipped with SAED and EDAX detectors confirm the presence of hexagonal lattice of Sn atoms. The position of Raman peak along with the inter-planar ‘d’ spacing obtained from SAED for prepared samples are in good agreement with that obtained from first principles calculations and confirm that the sheets are not (111) α-Sn sheets. Further, the optical signature calculated using density functional theory at ~191 nm and ~233 nm for low buckled stanene are in qualitative agreement with the measured UV-Vis absorption spectrum. AFM measurements suggest interlayer spacing of ~0.33 nm in good agreement with that reported for epitaxial stanene sheets. No traces of oxygen were observed in the EDAX spectrum suggesting the absence of any oxidized phases. This is also confirmed by Raman measurements by comparing with oxidized stanene sheets. PMID:27492139

  17. Stanene: Atomically Thick Free-standing Layer of 2D Hexagonal Tin

    NASA Astrophysics Data System (ADS)

    Saxena, Sumit; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-08-01

    Stanene is one of most important of 2D materials due to its potential to demonstrate room temperature topological effects due to opening of spin-orbit gap. In this pursuit we report synthesis and investigation of optical properties of stanene up to few layers, a two-dimensional hexagonal structural analogue of graphene. Atomic scale morphological and elemental characterization using HRTEM equipped with SAED and EDAX detectors confirm the presence of hexagonal lattice of Sn atoms. The position of Raman peak along with the inter-planar ‘d’ spacing obtained from SAED for prepared samples are in good agreement with that obtained from first principles calculations and confirm that the sheets are not (111) α-Sn sheets. Further, the optical signature calculated using density functional theory at ~191 nm and ~233 nm for low buckled stanene are in qualitative agreement with the measured UV-Vis absorption spectrum. AFM measurements suggest interlayer spacing of ~0.33 nm in good agreement with that reported for epitaxial stanene sheets. No traces of oxygen were observed in the EDAX spectrum suggesting the absence of any oxidized phases. This is also confirmed by Raman measurements by comparing with oxidized stanene sheets.

  18. Impact of metal nano layer thickness on tunneling oxide and memory performance of core-shell iridium-oxide nanocrystals

    SciTech Connect

    Banerjee, W.; Maikap, S.; Tien, T.-C.; Li, W.-C.; Yang, J.-R.

    2011-10-01

    The impact of iridium-oxide (IrO{sub x}) nano layer thickness on the tunneling oxide and memory performance of IrO{sub x} metal nanocrystals in an n-Si/SiO{sub 2}/Al{sub 2}O{sub 3}/IrO{sub x}/Al{sub 2}O{sub 3}/IrO{sub x} structure has been investigated. A thinner (1.5 nm) IrO{sub x} nano layer has shown better memory performance than that of a thicker one (2.5 nm). Core-shell IrO{sub x} nanocrystals with a small average diameter of 2.4 nm and a high density of {approx}2 x 10{sup 12}/cm{sup 2} have been observed by scanning transmission electron microscopy. The IrO{sub x} nanocrystals are confirmed by x-ray photoelectron spectroscopy. A large memory window of 3.0 V at a sweeping gate voltage of {+-}5 V and 7.2 V at a sweeping gate voltage of {+-} 8 V has been observed for the 1.5 nm-thick IrO{sub x} nano layer memory capacitors with a small equivalent oxide thickness of 8 nm. The electrons and holes are trapped in the core and annular regions of the IrO{sub x} nanocrystals, respectively, which is explained by Gibbs free energy. High electron and hole-trapping densities are found to be 1.5 x 10{sup 13}/cm{sup 2} and 2 x 10{sup 13}/cm{sup 2}, respectively, due to the small size and high-density of IrO{sub x} nanocrystals. Excellent program/erase endurance of >10{sup 6} cycles and good retention of 10{sup 4} s with a good memory window of >1.2 V under a small operation voltage of {+-} 5 V are obtained. A large memory size of >10 Tbit/sq. in. can be designed by using the IrO{sub x} nanocrystals. This study is not only important for the IrO{sub x} nanocrystal charge-trapping memory investigation but it will also help to design future metal nanocrystal flash memory.

  19. Effects of Co layer thickness and annealing temperature on the magnetic properties of inverted [Pt/Co] multilayers

    SciTech Connect

    Lee, Tae Young; Chan Won, Young; Su Son, Dong; Lee, Seong-Rae; Ho Lim, Sang

    2013-11-07

    The effects of Co layer thickness and annealing temperature on the perpendicular magnetic anisotropy (PMA) properties of inverted [Pt (0.2 nm)/Co (t{sub Co})]{sub 6} multilayers (where t{sub Co} indicates the thickness of the Co layer) have been investigated. The cross-sectional microstructure, as observed from the high-resolution transmission electron microscope images, shows a clear layered structure with atomically flat interfaces both in the as-deposited state as well as after annealing, indicating the interface effects for PMA. The effective PMA energy density (K{sub eff}) increases significantly with an increase in t{sub Co} from 0.2 to 0.28 nm and then becomes almost saturated with further increases in t{sub Co}, followed by a slight reduction at the highest Co thickness, t{sub Co} = 0.6 nm. In order to explain the t{sub Co} dependence on K{sub eff}, the intrinsic PMA energy density (K{sub i}) is calculated by additionally measuring a similar set of results for the saturation magnetization. The K{sub i} value increases nearly linearly with the increase in t{sub Co} from 0.2 to 0.5 nm, followed by saturation at a higher t{sub Co} value of 0.6 nm. Owing to a close relationship between K{sub i} and the quality of the interfaces, these results indicate a similar t{sub Co} dependence on the quality of the interfaces. This is further supported from the magnetic measurements of the samples annealed at the highest temperature of 500 °C, where a second phase is formed, which show a similar t{sub Co} dependence on the amount of the second phase. The K{sub i} value is nearly independent of the annealing temperature at t{sub Co} ≤ 0.4 nm, above which a substantial reduction is observed, when the annealing temperature exceeds 500 °C.

  20. Strain-free GaN thick films grown on single crystalline ZnO buffer layer with in situ lift-off technique

    SciTech Connect

    Lee, S. W.; Minegishi, T.; Lee, W. H.; Goto, H.; Lee, H. J.; Lee, S. H.; Lee, Hyo-Jong; Ha, J. S.; Goto, T.; Hanada, T.; Cho, M. W.; Yao, T.

    2007-02-05

    Strain-free freestanding GaN layers were prepared by in situ lift-off process using a ZnO buffer as a sacrificing layer. Thin Zn-polar ZnO layers were deposited on c-plane sapphire substrates, which was followed by the growth of Ga-polar GaN layers both by molecular beam epitaxy (MBE). The MBE-grown GaN layer acted as a protecting layer against decomposition of the ZnO layer and as a seeding layer for GaN growth. The ZnO layer was completely in situ etched off during growth of thick GaN layers at low temperature by hydride vapor phase epitaxy. Hence freestanding GaN layers were obtained for the consecutive growth of high-temperature GaN thick layers. The lattice constants of freestanding GaN agree with those of strain-free GaN bulk. Extensive microphotoluminescence study indicates that strain-free states extend throughout the high-temperature grown GaN layers.

  1. Effects of low-temperature buffer-layer thickness and growth temperature on the SEE sensitivity of GaAs HIGFET circuits

    SciTech Connect

    Weatherford, T.R.; Fouts, D.J.; Marshall, P.W. |; Marshall, C.J.; Mathes, B.; LaMacchia, M.

    1997-12-01

    Heavy-ion Single Event Effects (SEE) test results reveal the role of growth temperature and buffer layer thickness in the use of a low-temperature grown GaAs (LT GaAs) buffer layer for suppressing SEE sensitivity in GaAs HIGFET circuits.

  2. Enhanced performance and stability in PBDTTT-C-T : PC70 BM polymer solar cells by optimizing thickness of NiOx buffer layers

    NASA Astrophysics Data System (ADS)

    Fan, Xi; Fang, Guojia; Cheng, Fei; Qin, Pingli; Huang, Huihui; Li, Yongfang

    2013-07-01

    We report efficient polymer solar cells (PSCs) based on PBDTTT-C-T : PC70BM with a NiOx anode buffer layer (thickness of 3-15 nm) prepared by radio-frequency magnetron sputtering deposition. The PSC with the optimum NiOx buffer layer thickness of 9 nm showed the highest power conversion efficiency of 7.42% with Voc of 0.75 V, Jsc of 15.82 mA cm-2 and FF of 62.5%, which was higher than that of the PSCs with a PEDOT : PSS buffer layer. Moreover, compared with the PSCs with a PEDOT : PSS buffer layer, the PSCs with the optimum NiOx buffer layer exhibited a better stability under N2 atmosphere. The results indicate that the sputtered 9 nm thick NiOx buffer layer is superior to the PEDOT : PSS buffer layer not only for better performance but also for improved long-term stability. The optimized NiOx buffer layer thickness possesses an appropriate energy level matching with PBDTTT-C-T, which results in effective hole collection and improved photovoltaic performance.

  3. Effect of layer thickness in selective laser melting on microstructure of Al/5 wt.%Fe2O3 powder consolidated parts.

    PubMed

    Dadbakhsh, Sasan; Hao, Liang

    2014-01-01

    In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75  μm layer thickness, and 50  μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process. PMID:24526879

  4. Effect of Layer Thickness in Selective Laser Melting on Microstructure of Al/5 wt.%Fe2O3 Powder Consolidated Parts

    PubMed Central

    Hao, Liang

    2014-01-01

    In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75 μm layer thickness, and 50 μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process. PMID:24526879

  5. A novel ground surface subsidence prediction model for sub-critical mining in the geological condition of a thick alluvium layer

    NASA Astrophysics Data System (ADS)

    Chang, Zhanqiang; Wang, Jinzhuang; Chen, Mi; Ao, Zurui; Yao, Qi

    2015-06-01

    A substantial number of the coal mines in China are in the geological condition of thick alluvium layer. Under these circumstances, it does not make sense to predict ground surface subsidence and other deformations by using conventional prediction models. This paper presents a novel ground surface subsidence prediction model for sub-critical mining in the geological condition of thick alluvium layer. The geological composition and mechanical properties of thick alluvium is regarded as a random medium, as are the uniformly distributed loads on rock mass; however, the overburden of the rock mass in the bending zone is looked upon as a hard stratum controlling the ground surface subsidence. The different subsidence and displacement mechanisms for the rock mass and the thick alluvium layer are respectively considered and described in this model, which indicates satisfactory performances in a practical prediction case.

  6. Effect of change in macular birefringence imaging protocol on retinal nerve fiber layer thickness parameters using GDx VCC in eyes with macular lesions.

    PubMed

    Dada, Tanuj; Tinwala, Sana I; Dave, Vivek; Agarwal, Anand; Sharma, Reetika; Wadhwani, Meenakshi

    2014-08-01

    This study evaluates the effect of two macular birefringence protocols (bow-tie retardation and irregular macular scan) using GDx VCC on the retinal nerve fiber layer (RNFL) thickness parameters in normal eyes and eyes with macular lesions. In eyes with macular lesions, the standard protocol led to significant overestimation of RNFL thickness which was normalized using the irregular macular pattern protocol. In eyes with normal macula, absolute RNFL thickness values were higher in irregular macular pattern protocols with the difference being statistically significant for all parameters except for inferior average thickness. This has implications for monitoring glaucoma patients who develop macular lesions during the course of their follow-up. PMID:24469116

  7. Atomic diffusion across Ni50Ti50—Cu explosive welding interface: Diffusion layer thickness and atomic concentration distribution

    NASA Astrophysics Data System (ADS)

    Chen, Shi-Yang; Wu, Zhen-Wei; Liu, Kai-Xin

    2014-06-01

    Molecular dynamics simulations are carried out to study atomic diffusion in the explosive welding process of Ni50Ti50—Cu (at.%). By using a hybrid method which combines molecular dynamics simulation and classical diffusion theory, the thickness of the diffusion layer and the atomic concentration distribution across the welding interface are obtained. The results indicate that the concentration distribution curves at different times have a geometric similarity. According to the geometric similarity, the atomic concentration distribution at any time in explosive welding can be calculated. Ni50Ti50—Cu explosive welding and scanning electron microscope experiments are done to verify the results. The simulation results and the experimental results are in good agreement.

  8. Polarized bidirectional reflectance of optically thick sparse particulate layers: An efficient numerically exact radiative-transfer solution

    NASA Astrophysics Data System (ADS)

    Mishchenko, Michael I.; Dlugach, Janna M.; Chowdhary, Jacek; Zakharova, Nadezhda T.

    2015-05-01

    We describe a simple yet efficient numerical algorithm for computing polarized bidirectional reflectance of an optically thick (semi-infinite), macroscopically flat layer composed of statistically isotropic and mirror symmetric random particles. The spatial distribution of the particles is assumed to be sparse, random, and statistically uniform. The 4×4 Stokes reflection matrix is calculated by iterating the Ambartsumian's vector nonlinear integral equation. The result is a numerically exact solution of the vector radiative transfer equation and as such fully satisfies the energy conservation law and the fundamental reciprocity relation. Since this technique bypasses the computation of the internal radiation field, it is very fast and highly accurate. The FORTRAN implementation of the technique is publicly available on the World Wide Web at

  9. Flutter Sensitivity to Boundary Layer Thickness, Structural Damping, and Static Pressure Differential for a Shuttle Tile Overlay Repair Concept

    NASA Technical Reports Server (NTRS)

    Scott, Robert C.; Bartels, Robert E.

    2009-01-01

    This paper examines the aeroelastic stability of an on-orbit installable Space Shuttle patch panel. CFD flutter solutions were obtained for thick and thin boundary layers at a free stream Mach number of 2.0 and several Mach numbers near sonic speed. The effect of structural damping on these flutter solutions was also examined, and the effect of structural nonlinearities associated with in-plane forces in the panel was considered on the worst case linear flutter solution. The results of the study indicated that adequate flutter margins exist for the panel at the Mach numbers examined. The addition of structural damping improved flutter margins as did the inclusion of nonlinear effects associated with a static pressure difference across the panel.

  10. Dependence of deposition parameters and layer thickness on the characteristics of Nd-Fe-B thin films

    NASA Astrophysics Data System (ADS)

    Madeswaran, S.; Tokumaru, R.; Tamano, S.; Goto, S.; Tokiwa, K.; Watanabe, T.

    2009-11-01

    Textured Nd-Fe-B thin films with hard magnetic properties were prepared on a Ta (110) buffer layered glass substrates using radio frequency (RF) sputtering deposition. We investigated the influence of substrate temperature, sputtering gas pressure, RF power and film thickness on their microstructural and magnetic properties. Composition in the Nd-Fe-B thin films prepared using the same target with an Nd/Fe ratio of 0.32 was markedly changed (varied between 0.21 and 0.31) depending on the Ar pressure and the RF power. Well-textured Nd-Fe-B films grown at a deposition pressure of 7.0 Pa, a temperature of 550 °C, and a power of 100 W revealed better magnetic properties: Jr = 1.1 T, Hc = 1130 kA/m and BH(max) = 236 kJ/m3.

  11. Directional Emission from Metal-Dielectric-Metal Structures: Effect of Mixed Metal Layers, Dye Location and Dielectric Thickness

    PubMed Central

    Choudhury, Sharmistha Dutta; Badugu, Ramachandram; Ray, Krishanu; Lakowicz, Joseph R.

    2015-01-01

    Metal-dielectric-metal (MDM) structures provide directional emission close to the surface normal, which offers opportunities for new design formats in fluorescence based applications. The directional emission arises due to near-field coupling of fluorophores with the optical modes present in the MDM substrate. Reflectivity simulations and dispersion diagrams provide a basic understanding of the mode profiles and the factors that affect the coupling efficiency and the spatial distribution of the coupled emission. This work reveals that the composition of the metal layers, the location of the dye in the MDM substrate and the dielectric thickness are important parameters that can be chosen to tune the color of the emission wavelength, the angle of observation, the angular divergence of the emission and the polarization of the emitted light. These features are valuable for displays and optical signage. PMID:25844110

  12. Thermal elasto/visco-plastic analysis of multi-layered moderately thick shells of revolution under thermal loading due to fluid

    SciTech Connect

    Inamura, E.; Takezono, S.; Tao, K.

    1996-12-01

    An analytical formulation and a numerical solution of the thermal elasto/visco-plastic deformation of multi-layered moderately thick shells of revolution subjected to thermal loads due to fluid are developed. The temperature distribution through each layer thickness is assumed to be a quadratic curve and is determined using the equations of heat conduction and heat transfer. The equations of equilibrium and the relations between the strains and displacements are derived from the Reissner-Naghdi theory. For the constitutive relations, the Perzyna equations are employed. As numerical examples, two-layered cylindrical shells composed of mild steel and titanium subjected to thermal loads due to fluid are analyzed.

  13. Mo layer thickness requirement on the ion source back plate for the HNB and DNB ion sources in ITER

    NASA Astrophysics Data System (ADS)

    Singh, M. J.; De Esch, H. P. L.; Hemsworth, R.; Boilson, D.

    2015-04-01

    All the inner surfaces of the ion sources and the upstream surface of the plasma grid of the ITER neutral beam ion sources are proposed to be coated with molybdenum. This is done to avoid sputtering of the base material (Cu or CuCrZr) by the ions in the source plasma (D+, D2+, D3+ or H+, H2+, H3+). The sputtering of Mo by the ions in the source plasma is low compared to that from Cu, and the threshold energy for sputtering ˜80 eV) is high compared to the energy of the ions in the source. However the D2+, H2+ and D+, H+ ions backstreaming from the accelerators will have energies that substantially exceed that threshold and it is important that the Mo layer is not eroded such that the base material is exposed to the source plasma. In the case of the HNB, the backstreaming ion power is calculated to be in the order of ˜1 MW, and the average energy of the backstreaming ions is calculated to be ˜300 keV. The ion sources in the HNB beam lines, 40 A 1 MeV D and 46 A 870 keV H beams, are supposed to operate for a period of 2 x 107 s. For the DNB, 60 A 100 keV H beams, the corresponding number is 1.4 × 106 s considering a beam duty cycle of 3s ON/20s OFF with 5 Hz modulation. The Mo layer on the ion source back plate should be thick enough to survive this operational time. Thickness estimation has been carried out taking into account the sputtering yields (atoms/ion), the energy spectrum of the backstreaming ions and the estimated profiles on the ion source back plate.

  14. The effect of inlet boundary layer thickness on the flow within an annular S-shaped duct

    SciTech Connect

    Sonoda, T.; Arima, T.; Oana, M.

    1999-07-01

    Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the geometry as that used to connect compressor spools on the experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e., thin and thick IBL) were used. Results showed that large differences of flow patterns were observed at the S-shaped duct exit between two types of IBL, though the value of net total pressure loss has not been remarkably changed. According to overall total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor performance. There is a much-distorted three-dimensional flow patterns at the exit of S-shaped duct. This means that the aerodynamic sensitivity of S-shaped duct to the IBL thickness is very high. Therefore, sufficient care is needed to design not only downstream aerodynamic components (for example, centrifugal impeller) but also upstream aerodynamic components (LPC OGV).

  15. Nanometer-thick amorphous-SnO2 layer as an oxygen barrier coated on a transparent AZO electrode

    NASA Astrophysics Data System (ADS)

    Lee, Hee Sang; Woo, Seong Ihl

    2016-07-01

    It is necessary for transparent conducting electrodes used in dye-sensitized or perovskite solar cells to have high thermal stability which is required when TiO2 is coated on the electrode. AZO films with their low-cost and good TCO properties are unfortunately unstable above 300 °C in air because of adsorbed oxygen. In this paper, the thermal stability of AZO films is enhanced by depositing an oxygen barrier on AZO films to block the oxygen. As the barrier material, SnO2 is used due to its high heat stability, electrical conductivity, and transmittance. Moreover, when the SnO2 is grown as amorphous phase, the protective effect become greater than the crystalline phase. The thermal stability of the amorphous-SnO2/AZO films varies depending on the thickness of the amorphous SnO2 layer. Because of the outstanding oxygen blocking properties of amorphous SnO2, its optimal thickness is very thin and it results in only a slight decrease in transmittance. The sheet resistance of the amorphous-SnO2/AZO film is 5.4 Ω sq-1 after heat treatment at 500 °C for 30 min in air and the average transmittance in the visible region is 83.4%. The results show that the amorphous-SnO2/AZO films have thermal stability with excellent electrical and optical properties. [Figure not available: see fulltext.

  16. Dependence of Sheet Resistance of CoSi2 with Gate Length of 30 nm on Thickness of Titanium Nitride Capping Layer in Co-Salicide Process

    NASA Astrophysics Data System (ADS)

    Kawamura, Kazuo; Inagaki, Satoshi; Saiki, Takashi; Nakamura, Ryo; Kataoka, Yuji; Kase, Masataka

    2007-11-01

    Since the distribution of gate resistance using cobalt silicide (CoSi2) increases markedly for gate lengths of 30 nm or less, CoSi2 is now being replaced by NiSi. However, CoSi2 still has the advantages of a high thermal stability and a low degree of roughness at the interface between the silicide and silicon layers owing to the low degree of mismatch (1.2%) of between their lattice constants. We have achieved excellent sheet resistance (Rs) with a gate length Lg=30 nm by optimizing the thickness of a cobalt capping layer of titanium nitride. The results shows an abnormal Rs behavior, in which one σ of Rs increases with capping layer thickness in the range of 10-50 nm, while it decreases with increasing capping layer thickness in the range of 0-10 nm. Unlike the results of a previous report [K. Goto et al.: IEDM Tech. Dig., 1995, p. 449], the variation in the Rs with a gate length Lg=30 nm is small, even without a TiN capping layer thickness down to 5-10 nm. We suggest that the uniformity of Rs is determined by the thickness of the CoSi layer after selective etching and the titanium concentration in the CoSi layer for capping TiN thicknesses of 10-50 nm, while the uniformity is determined by the titanium concentration and the damage sustained during selective etching for TiN thickness of 0-10 nm. For this optimization, CoSi2 is applicable to the 65 nm node technology node or beyond.

  17. Scaling relationships for diffusive boundary layer thickness and diffusive flux based on in situ measurements in coastal seas

    NASA Astrophysics Data System (ADS)

    Wang, Jianing; Zhao, Liang; Fan, Renfu; Wei, Hao

    2016-05-01

    In situ measurements of the diffusive boundary layer (DBL) and bottom boundary layer (BBL) under different dynamic and oxygen environments in three coastal seas are analyzed. Previous scaling methods for the DBL thickness (δDBL) are summarized. Three methods that lead to consistent dimensions at both sides of the derived relationships have all been rooted in the Batchelor length scale. The method representing the Batchelor length scale as a function of flow speed (U) is found to be the most appropriate for scaling δDBL when the law of wall applies. Diffusive flux is controlled by the dynamic-forced δDBL and the difference in oxygen concentration over the DBL (ΔC). Values of ΔC could be scaled using the oxygen concentration of the BBL (CBBL) and the normalized benthic temperature. An effective method is developed for scaling the diffusive flux based on measurements of benthic temperature, salinity, U, CBBL, and the estimation of bottom roughness. The scaling of δDBL based mainly on U and the scaling of diffusive flux well fit data from the three sites, despite their distinct differences in dynamic and oxygen environments.

  18. Non-cellulosic polysaccharides help to reveal the history of thick organic surface layers on calcareous Alpine soils

    NASA Astrophysics Data System (ADS)

    Prietzel, Jörg; Spielvogel, Sandra

    2015-04-01

    We investigated the potential of non-cellulosic polysaccharides (NCP) as biomarkers to identify the plant types that dominate present and past litter input into organic surface covers on calcareous Alpine soils and to reveal historic vegetation changes. At two sites in the Alps, NCP monomers were quantified in different organs of site-dominating plants, the Oa horizon of four Folic Leptosols, and different sections of thick organic surface layers of four Folic Histosols on calcareous bedrock. The dominating plant types at our study sites differ markedly in their NCP composition and (galactose + mannose)/(arabinose + xylose) [GM/AX] ratio (grasses and sedges: 0.2; dicots Fagus and Vaccinium: 0.2-0.6; conifers Abies, Picea, Pinus: 0.7-2.4; mosses: 5). For all except one soil, the NCP signature of the uppermost Oa horizon reflects the present vegetation. For all Histosol O horizons, NCP signatures indicate a dominance of conifer litter throughout their development (up to 1,500 years). Different NCP and GM/AX depth profiles reflect specific patterns of O layer genesis. From those results we conclude that NCP and GM/AX depth profiles in organic surface covers of soils provide important information about dominating litter sources in the past and can be valuable tools to reveal historic vegetation and/ or land use changes.

  19. Thickness dependence of the MoO3 blocking layers on ZnO nanorod-inverted organic photovoltaic devices

    PubMed Central

    Wang, Mingjun; Li, Yuan; Huang, Huihui; Peterson, Eric D.; Nie, Wanyi; Zhou, Wei; Zeng, Wei; Huang, Wenxiao; Fang, Guojia; Sun, Nanhai; Zhao, Xingzhong; Carroll, David L.

    2011-01-01

    Organic solar cells based on vertically aligned zinc oxide nanorod arrays (ZNR) in an inverted structure of indium tin oxide (ITO)∕ZNR∕poly(3-hexylthiophene): (6,6)-phenyl C61 butyric acid methyl ester(P3HT:PCBM)∕MoO3∕aluminum(Al) were studied. We found that the optimum MoO3 layer thickness condition of 20 nm, the MoO3 can effectively decrease the probability of bimolecular recombination either at the Al interface or within the active layer itself. For this optimum condition we get a power conversion efficiency of 2.15%, a short-circuit current density of 9.02 mA∕cm2, an open-circuit voltage of 0.55V, and a fill factor of 0.44 under 100 mW∕cm2 irradiation. Our investigations also show that the highly crystallized ZNR can create short and continuous pathways for electron transport and increase the contact area between the ZNR and the organic materials. PMID:21464889

  20. Impact of residual stress on the adhesion and tensile fracture of TiN/CrN multi-layered coatings from first principles

    NASA Astrophysics Data System (ADS)

    Yin, Deqiang; Peng, Xianghe; Qin, Yi; Wang, Zhongchang

    2012-06-01

    Multilayered TiN/CrN coatings find a wide range of technological applications where their internal hetero-interfaces and corresponding residual stress have been long suspected as capable of influencing their intriguing mechanical and chemical performances such as the thermal stability, hardness, and corrosion, tribological and wear resistance. Here, we investigate, by first-principles calculations, atomic and electronic structures of the TiN/CrN interface and how the residual stress influences the adhesion and ideal tensile strength of the multilayered coatings. We find that calculated adhesion energies of the interfaces with (1 1 1) and (0 0 1) orientations are small under no residual stress, yet increase almost linearly when the residual stress is imposed, suggesting that the residual stress plays a dominant role in affecting adhesion. The strengthened adhesion affected by the residual stress is found to be attributable to the stress-induced shrinkage of bonds, which results in enhanced interactions between the bonds in the TiN/CrN coatings. Using several analytic techniques, we have characterized the electronic structure of the interface carefully and determined the interfacial bonding to be primarily ionic with a small degree of covalency. The tensile simulations reveal that the interface with the (1 1 1) texture is more brittle than that with the (0 0 1), although the former presents greater ideal tensile strength. The findings presented here shed light on the impact of residual stress on the adhesion and ideal tensile strength of the TiN/CrN multi-layers, which information could be hard to obtain by means of experiments alone but which is of practical importance for further understanding and improvement of the multi-layered coatings at atomic scale.

  1. Effects of total thickness on (001) texture, surface morphology, and magnetic properties of [Fe/Pt]{sub n} multilayer films by monatomic layer deposition

    SciTech Connect

    Yu, Y. S.; George, T. A.; Yue, L. P.; Sellmyer, D. J.; Li, W. L.; Fei, W. D.; Li Haibo; Liu Mei

    2010-10-15

    Atomic-scale [Fe/Pt]{sub n} multilayer films with different total thickness were prepared on thermally oxidized Si (100) substrates at room temperature by monatomic layer deposition using dc-magnetron and rf-magnetron sputtering. Effects of the total thickness on (001) texture, surface morphology, and magnetic properties of the postannealed films have been investigated. It is found that the particlelike structure films with perfect (001) texture and perpendicular magnetic anisotropy are obtained with a thickness of less than or equal to 6.5 nm. After 500 deg. C annealing, the films with thickness of 6.5 and 11.9 nm show very smooth surface. In addition, with increasing total thickness of the films, (001) texture and perpendicular magnetic anisotropy of the annealed films deteriorate, and the films become continuous in structure. The total thickness of the films also affects the exchange-coupling interaction among FePt magnetic grains and the magnetization reversal process.

  2. Interlayer electronic hybridization leads to exceptional thickness-dependent vibrational properties in few-layer black phosphorus

    NASA Astrophysics Data System (ADS)

    Hu, Zhi-Xin; Kong, Xianghua; Qiao, Jingsi; Normand, Bruce; Ji, Wei

    2016-01-01

    Stacking two-dimensional (2D) materials into multi-layers or heterostructures, known as van der Waals (vdW) epitaxy, is an essential degree of freedom for tuning their properties on demand. Few-layer black phosphorus (FLBP), a material with high potential for nano- and optoelectronics applications, appears to have interlayer couplings much stronger than graphene and other 2D systems. Indeed, these couplings call into question whether the stacking of FLBP can be governed only by vdW interactions, which is of crucial importance for epitaxy and property refinement. Here, we perform a theoretical investigation of the vibrational properties of FLBP, which reflect directly its interlayer coupling, by discussing six Raman-observable phonons, including three optical, one breathing and two shear modes. With increasing sample thickness, we find anomalous redshifts of the frequencies for each optical mode but a blueshift for the armchair shear mode. Our calculations also show splitting of the phonon branches, due to anomalous surface phenomena, and strong phonon-phonon coupling. By computing uniaxial stress effects, inter-atomic force constants and electron densities, we provide a compelling demonstration that these properties are the consequence of strong and highly directional interlayer interactions arising from the electronic hybridization of the lone electron-pairs of FLBP, rather than from vdW interactions. This exceptional interlayer coupling mechanism controls the stacking stability of BP layers and thus opens a new avenue beyond vdW epitaxy for understanding the design of 2D heterostructures.Stacking two-dimensional (2D) materials into multi-layers or heterostructures, known as van der Waals (vdW) epitaxy, is an essential degree of freedom for tuning their properties on demand. Few-layer black phosphorus (FLBP), a material with high potential for nano- and optoelectronics applications, appears to have interlayer couplings much stronger than graphene and other 2D

  3. THE THICKNESS DEPENDENCE OF OXYGEN PERMEABILITY IN SOL-GEL DERIVED CGO-COFE2O4 THIN FILMS ON POROUS CERAMIC SUBSTRATES: A SPUTTERED BLOCKING LAYER FOR THICKNESS CONTROL

    SciTech Connect

    Brinkman, K

    2009-01-08

    Mixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membrane is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce{sub 0.8}Gd{sub 0.2}O{sub 2-{delta}} (CGO)-CoFe{sub 2}O{sub 4} (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ {approx} 50 nm sputtered CeO{sub 2} layers on the surface of porous CGO ceramic substrates which serve as solution 'blocking' layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of {approx} 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03 {micro}mol/cm{sup 2} s) at 800 C as compared to 1mm thick bulk ceramic membranes (0.003 {micro}mol/cm{sup 2}).

  4. Diamond-like carbon (DLC) thin film bioelectrodes: effect of thermal post-treatments and the use of Ti adhesion layer.

    PubMed

    Laurila, Tomi; Rautiainen, Antti; Sintonen, Sakari; Jiang, Hua; Kaivosoja, Emilia; Koskinen, Jari

    2014-01-01

    The effect of thermal post-treatments and the use of Ti adhesion layer on the performance of thin film diamond like carbon bioelectrodes (DLC) have been investigated in this work. The following results were obtained: (i) The microstructure of the DLC layer after the deposition was amorphous and thermal annealing had no marked effect on the structure, (ii) formation of oxygen containing SiOx and Ti[O,C] layers were detected at the Si/Ti and Ti/DLC interfaces with the help of transmission electron microscope (TEM), (iii) thermal post-treatments increased the polar fraction of the surface energy, (iv) cyclic voltammetry (CV) measurements showed that the DLC films had wide water windows and were stable in contact with dilute sulphuric acid and phosphate buffered saline (PBS) solutions, (v) use of Ti interlayer between Pt(Ir) microwire and DLC layer was crucial for the electrodes to survive the electrochemical measurements without the loss of adhesion of the DLC layer, (vi) DLC electrodes with small exposed Pt areas were an order of magnitude more sensitive towards dopamine than Pt electrodes and (vii) thermal post-treatments did not markedly change the electrochemical behavior of the electrodes despite the significant increase in the polar nature of the surfaces. It can be concluded that thin DLC bioelectrodes are stable under physiological conditions and can detect dopamine in micro molar range, but their sensitivity must be further improved. PMID:24268281

  5. Remotely Sensed Active Layer Thickness (ReSALT) from InSAR data near Toolik Lake in Northern Alaska

    NASA Astrophysics Data System (ADS)

    Chen, A. C.; Liu, L.; Schaefer, K. M.; Parsekian, A.; Jafarov, E. E.; Zebker, H. A.; Zhang, T.

    2014-12-01

    Toolik Field Station is built on spatially continuous permafrost on the north slope of Alaska. Seasonal surface subsidence and uplift occurs in permafrost regions due to thaw settlement and frost heave as the active layer thaws and refreezes. Using L-band (23.6 cm wavelength) InSAR data from ALOS-PALSAR acquired between 2006 and 2010, we use a small-baseline subset (SBAS) method to estimate seasonal surface subsidence and retrieve fine-resolution maps of active layer thickness (ALT) for a ~25x25 km area surrounding Toolik Field Station (located at 68.63°N, -149.60°E). We compare these remotely sensed ALT (ReSALT) results with in situ data from: 1) the Circumpolar Active Layer Monitoring (CALM) network showing mean ALT of ~40-50 cm in the region surrounding Toolik Field Station, corresponding to seasonal subsidence of 1 to 2 cm, and 2) mechanical probing measurements of ALT, obtained during field work in the study area in August 2014. We also solve for secular subsidence trends from the InSAR data. The trends are close to zero in most places, but larger subsidence trends in some isolated areas could be due to thermokarst processes (long-term thawing of ice-rich permafrost). We note, however, that downslope motion due to gelifluction cannot be separated from vertical thermokarst-related deformation without incorporating InSAR measurements from multiple look angles. Two key limitations to our method are the spatial variability of volumetric soil moisture content and the accuracy of the DEM needed to correct for topographic effects. We investigate the use of bulk volumetric water content inferred from ground-penetrating radar (GPR) data to improve the ReSALT retrieval algorithm. We also quantify the effect of DEM accuracy on ReSALT uncertainties, leads to requirements for DEM accuracy in InSAR-based ALT retrieval.

  6. High-temperature stability of c-Si surface passivation by thick PECVD Al2O3 with and without hydrogenated capping layers

    NASA Astrophysics Data System (ADS)

    Saint-Cast, Pierre; Kania, Daniel; Heller, René; Kuehnhold, Saskia; Hofmann, Marc; Rentsch, Jochen; Preu, Ralf

    2012-08-01

    We are studying the thermal stability of thick hydrogenated amorphous aluminum oxide (Al2O3) layers (20-50 nm) prepared by a high-throughput plasma-enhanced chemical-vapor-deposition (PECVD) technique for the electrical passivation of crystalline silicon surfaces. These passivation layers can be applied alone or covered by a capping layer like amorphous hydrogenated silicon nitride (SiNx) or amorphous hydrogenated silicon oxide (SiOx), also prepared by PECVD. After firing at 870 °C for approximately 3 s, the layers show blistering for Al2O3 of 30 nm or higher, independently from the capping layer. For thinner Al2O3, no blistering can be observed even using scanning electron microscope (SEM). Very long carrier lifetimes up to 900 μs was obtained in passivated p-Si (1 Ωcm) wafer after annealing and firing, without observing a strong influence of the layer thickness and the capping layer. All the layer stacks, including the stacks with SiNx capping layer, show high negative charge densities in the layer (1-4 × 1012 cm-2). Additionally, low interface defect densities (˜1011 cm-2 eV-1), which could be achieved with and without a hydrogenated capping layer, were measured even after firing. To explain these phenomena, hydrogen concentration depth profiles were measured by nuclear reaction analysis. These measurements have shown that, at the Al2O3-Si interface, hydrogen atomic concentration ranging 5-7% after annealing and 4% after firing are obtained independently from the capping hydrogen concentration. We conclude that PECVD Al2O3 layers of 20 nm or thicker can provide enough hydrogen to passivate the interface defects, even after a high temperature step. However, the layer thickness should be limited to 30 nm in order to avoid the blistering.

  7. Effects of electrical and optical properties of thickness condition of ZnO nanorod array layer for efficient electrochemical luminescence cell device

    NASA Astrophysics Data System (ADS)

    Choi, Hye Su; Chansri, Pakpoom; Sung, Youl Moon

    2016-02-01

    In this paper, we report on electrochemical luminescence (ECL) cells with a ZnO nanorod (ZNR) layer. The investigated ECL cells were composed of F-doped SnO2 (FTO) glass/Ru(II)/ZNRs/FTO glass, which used a ZNR layer as an electrode and the Ru(II) complex [Ru(bpy)32+] as a light-emitting material. The ECL cells were fabricated by changing the thickness of ZNRs from 5 to 12.5 µm. The luminescence property of the ECL cells was strongly affected by the variation in the thickness of the ZNR layer. The threshold voltage for the light emission from the ECL cells was 2 V for 10 µm thick ZNRs, which was lower than that of the thickness of the ECL cells without a ZNR layer. Also, the intensity of luminance from the ECL cells with ZNRs was much higher than that from the ECL cells without ZNRs at the same operating voltage. The efficiency of the ECL cells without ZNRs measured at 3 V was 0.0049 lm/W, while those of the ECL cells with ZNRs were 0.0121, 0.0157, 0.0354, and 0.024 lm/W for the ZNRs layer thicknesses 5, 7.5, 10, and 12.5 µm, respectively. However, the peak light intensity at the wavelength was 623 nm which had not affected the all ZNRs thicknesses. The best lifetime of the ECL cells with these thicknesses was 40 min for ZNRs 10 µm. The use of the ZNR layer in the ECL cells significantly improves the luminescence performance.

  8. Adhesive joint evaluation by ultrasonic interface and lamb waves

    NASA Technical Reports Server (NTRS)

    Rokhlin, S. I.

    1986-01-01

    Some results on the application of interface and Lamb waves for the study of curing of thin adhesive layers were summarized. In the case of thick substrates (thickness much more than the wave length) the interface waves can be used. In this case the experimental data can be inverted and the shear modulus of the adhesive film may be explicitly found based on the measured interface wave velocity. It is shown that interface waves can be used for the study of curing of structural adhesives as a function of different temperatures and other experimental conditions. The kinetics of curing was studied. In the case of thin substrates the wave phenomena are much more complicated. It is shown that for successful measurements proper selection of experimental conditions is very important. This can be done based on theoretical estimations. For correctly selected experimental conditions the Lamb waves may be a sensitive probe of adhesive bond quality and may be used or cure monitoring.

  9. Robust and tailored wet adhesion in biopolymer thin films.

    PubMed

    Pettersson, Torbjörn; Pendergraph, Samuel A; Utsel, Simon; Marais, Andrew; Gustafsson, Emil; Wågberg, Lars

    2014-12-01

    Model layer-by-layer (LbL) assemblies of poly(allylamine hydrochloride) (PAH) and hyaluronic acid (HA) were fabricated in order to study their wet adhesive behavior. The film characteristics were investigated to understand the inherent structures during the assembly process. Subsequently, the adhesion of these systems was evaluated to understand the correlation between the structure of the film and the energy required to separate these LbL assemblies. We describe how the conditions of the LbL fabrication can be utilized to control the adhesion between films. The characteristics of the film formation are examined in the absence and presence of salt during the film formation. The dependence on contact time and LbL film thickness on the critical pull-off force and work of adhesion are discussed. Specifically, by introducing sodium chloride (NaCl) in the assembly process, the pull-off forces can be increased by a factor of 10 and the work of adhesion by 2 orders of magnitude. Adjusting both the contact time and the film thickness enables control of the adhesive properties within these limits. Based on these results, we discuss how the fabrication procedure can create tailored adhesive interfaces with properties surpassing analogous systems found in nature. PMID:25333327

  10. Identification of the Chemical Bonding Prompting Adhesion of a-C:H Thin Films on Ferrous Alloy Intermediated by a SiCx:H Buffer Layer.

    PubMed

    Cemin, F; Bim, L T; Leidens, L M; Morales, M; Baumvol, I J R; Alvarez, F; Figueroa, C A

    2015-07-29

    Amorphous carbon (a-C) and several related materials (DLCs) may have ultralow friction coefficients that can be used for saving-energy applications. However, poor chemical bonding of a-C/DLC films on metallic alloys is expected, due to the stability of carbon-carbon bonds. Silicon-based intermediate layers are employed to enhance the adherence of a-C:H films on ferrous alloys, although the role of such buffer layers is not yet fully understood in chemical terms. The chemical bonding of a-C:H thin films on ferrous alloy intermediated by a nanometric SiCx:H buffer layer was analyzed by X-ray photoelectron spectroscopy (XPS). The chemical profile was inspected by glow discharge optical emission spectroscopy (GDOES), and the chemical structure was evaluated by Raman and Fourier transform infrared spectroscopy techniques. The nature of adhesion is discussed by analyzing the chemical bonding at the interfaces of the a-C:H/SiCx:H/ferrous alloy sandwich structure. The adhesion phenomenon is ascribed to specifically chemical bonding character at the buffer layer. Whereas carbon-carbon (C-C) and carbon-silicon (C-Si) bonds are formed at the outermost interface, the innermost interface is constituted mainly by silicon-iron (Si-Fe) bonds. The oxygen presence degrades the adhesion up to totally delaminate the a-C:H thin films. The SiCx:H deposition temperature determines the type of chemical bonding and the amount of oxygen contained in the buffer layer. PMID:26135943

  11. Preparation of ultra-thin and high-quality WO3 compact layers and comparision of WO3 and TiO2 compact layer thickness in planar perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jincheng; Shi, Chengwu; Chen, Junjun; Wang, Yanqing; Li, Mingqian

    2016-06-01

    In this paper, the ultra-thin and high-quality WO3 compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO3 and TiO2 compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO2 compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO3 and TiO2 compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO3 compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO2 compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency.

  12. Last Decade of Changes in Ground Temperature and Active Layer Thickness in the High Canadian Arctic and in Barrow

    NASA Astrophysics Data System (ADS)

    Romanovsky, V. E.; Cable, W.; Walker, D. A.; Yoshikawa, K.; Marchenko, S. S.

    2013-12-01

    The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Most of the permafrost observatories in the Northern Hemisphere show substantial warming of permafrost since circa 1980-1990. The magnitude of warming has varied with location, but was typically from 0.5 to 2°C. Permafrost is already thawing within the southern part of the permafrost domain. However, recent observations documented propagation of this process northward into the continuous permafrost zone. The close proximity of the exceptionally icy soil horizons to the ground surface, which is typical for the arctic tundra biome, makes tundra surfaces extremely sensitive to the natural and human-made changes that may resulted in development of processes such as thermokarst, thermal erosion, and retrogressive thaw slumps that strongly affect the stability of ecosystems and infrastructure. In 2003-2005, three Ecological Permafrost Observatories where established in the High Canadian Arctic (Green Cabin on the Banks Island, Mould Bay on the Prince Patrick Island, and Isachsen on the Ellef Ringnes Island) as a part of the University of Alaska Fairbanks NSF funded Biocomplexity Project. These observatories represent the northern part of the North American Arctic Transect (NAAT) established as a result of this project. The climatic and ground temperature data collected at these observatories show a general warming trend similar to what has been observed at the other locations in the North American Arctic. An important result of this resent warming is a significant increase in the active layer thickness (ALT) during the last decade. For example, ALT at the Isachsen observatory increased from 0.4-0.42 m in 2005 to 0.54 m in 2012. The maximum ALT of 0.58 m was recorded in 2008. In a shallow excavation across an ice wedge at the Isachsen site, we estimated that the top of the ice wedge ice was located at 42

  13. Effect of boundary layer thickness before the flow separation on aerodynamic characteristics and heat transfer behind an abrupt expansion in a round tube

    NASA Astrophysics Data System (ADS)

    Terekhov, V. I.; Bogatko, T. V.

    2008-03-01

    Results of numerical investigation of the boundary layer thickness on turbulent separation and heat transfer in a tube with an abrupt expansion are shown. The Menter turbulence model of shear stress transfer implemented in Fluent package was used for calculations. The range of Reynolds numbers was from 5·103 to 105. The air was used as the working fluid. A degree of tube expansion was ( D 2/ D 1)2 = 1.78. A significant effect of thickness of the separated boundary layer both on dynamic and thermal characteristics of the flow is shown. In particular, it was found that with an increase in the boundary layer thickness the recirculation zone increases, and the maximum heat transfer coefficient decreases.

  14. The Relationship Between Retinal Nerve Fiber Layer Thickness and Optic Nerve Head Neuroretinal Rim Tissue in Glaucoma

    PubMed Central

    Patel, Nimesh B.; Sullivan-Mee, Michael; Harwerth, Ronald S.

    2014-01-01

    Purpose. The purpose of this study was to determine the relationship between optical coherence tomography (OCT) measures of retinal nerve fiber layer (RNFL) and neuroretinal rim (NRR) in a nonhuman primate experimental glaucoma model, and in a population of clinical patients. Methods. For nonhuman primates, normative data were collected from 44 healthy monkeys, and nine animals with unilateral experimental glaucoma that were followed longitudinally. Cross-sectional human subjects data were collected from 89 healthy, 74 glaucoma suspects, and 104 glaucoma patients. Individualized transverse scaling for OCT scans was calculated using a schematic eye that incorporated optical ocular biometry. Custom algorithms were used to quantify RNFL thickness with and without vessels removed, scaled minimum rim width (sMRW), and neural rim volume (NRV). Results. For the experimental glaucoma group, NRR parameters showed the first changes with increased cumulative IOP. The data for both NRR and RNFL measures were best fit by an exponential rise model (NRV, R2 = 0.79, P < 0.01, sMRW, R2 = 0.74, P < 0.01). The major retinal vascular thickness contribution to the RNFL decreased (0.03 μm/μm, P < 0.01) with RNFL loss, but the percent vascular contribution increased (−0.1%/μm, P < 0.01) with disease progression. Overall, the findings for the cross-sectional human data were similar to those of the experimental model. Conclusions. The findings illustrate a nonlinear relationship between NRR and RNFL measures and provide support for the use of multiple OCT scaled morphological measures for the diagnosis and management of primary open angle glaucoma in humans. PMID:25249610

  15. Mo layer thickness requirement on the ion source back plate for the HNB and DNB ion sources in ITER

    SciTech Connect

    Singh, M. J.; Hemsworth, R.; Boilson, D.; De Esch, H. P. L.

    2015-04-08

    All the inner surfaces of the ion sources and the upstream surface of the plasma grid of the ITER neutral beam ion sources are proposed to be coated with molybdenum. This is done to avoid sputtering of the base material (Cu or CuCrZr) by the ions in the source plasma (D{sup +}, D{sub 2}{sup +}, D{sub 3}{sup +} or H{sup +}, H{sub 2}{sup +}, H{sub 3}{sup +}). The sputtering of Mo by the ions in the source plasma is low compared to that from Cu, and the threshold energy for sputtering ∼80 eV) is high compared to the energy of the ions in the source. However the D{sub 2}{sup +}, H{sub 2}{sup +} and D{sup +}, H{sup +} ions backstreaming from the accelerators will have energies that substantially exceed that threshold and it is important that the Mo layer is not eroded such that the base material is exposed to the source plasma. In the case of the HNB, the backstreaming ion power is calculated to be in the order of ∼1 MW, and the average energy of the backstreaming ions is calculated to be ∼300 keV. The ion sources in the HNB beam lines, 40 A 1 MeV D and 46 A 870 keV H beams, are supposed to operate for a period of 2 x 10{sup 7} s. For the DNB, 60 A 100 keV H beams, the corresponding number is 1.4 × 10{sup 6} s considering a beam duty cycle of 3s ON/20s OFF with 5 Hz modulation. The Mo layer on the ion source back plate should be thick enough to survive this operational time. Thickness estimation has been carried out taking into account the sputtering yields (atoms/ion), the energy spectrum of the backstreaming ions and the estimated profiles on the ion source back plate.

  16. LPHN3, a presynaptic adhesion-GPCR implicated in ADHD, regulates the strength of neocortical layer 2/3 synaptic input to layer 5

    PubMed Central

    2014-01-01

    Background Latrophilins (LPHNs) are a small family of neuronal adhesion-GPCRs originally discovered as receptors for the black widow spider toxin α-latrotoxin. Mutations in LPHN3 have recently been identified as risk factors for attention deficit hyperactivity disorder (ADHD) in humans, but their physiological function has remained elusive. In this study, we tested two hypotheses regarding LPHN3 function: (1) LPHN3 regulates synaptic transmission by modulating probability of release; and (2) LPHN3 controls synapse development and the abundance of synapses. Results We manipulated LPHN3 expression in mouse layer 2/3 (L2/3) pyramidal neurons and examined the consequences on the L2/3 to L5 cortical microcircuit. Employing an optogenetic strategy combined with shRNA knockdown of LPHN3, we found that LPHN3 did not influence probability of release at synapses formed by L2/3 neurons onto L5 pyramidal cells. The strength of L2/3 afferent input to L5, however, was weakened by loss of LPHN3. Using Synaptophysin-GFP as an anatomical marker of presynaptic terminals, we found that the density of synapses formed by L2/3 axons in L5 was reduced when LPHN3 was lost. Finally, we investigated the structural organization of the extracellular domain of LPHN3. We used single particle negative stain electron microscopy to image the extracellular domain of LPHN3 and showed that the Olfactomedin and Lectin domains form a globular domain on an elongated stalk. Cell-based binding experiments with mutant proteins revealed that the Olfactomedin domain was required for binding to FLRT3, whereas both the Olfactomedin and Lectin domains were involved in binding to Teneurin 1. Mutant LPHN3 lacking the Olfactomedin domain was not capable of rescuing the deficit in presynaptic density following knockdown of endogenous LPHN3. Conclusions We find that LPHN3 regulates the number of synapses formed by L2/3 neurons in L5 and the strength of synaptic drive from the L2/3-L5 pathway. The Olfactomedin

  17. The Effect of the Inlet Mach Number and Inlet-boundary-layer Thickness on the Performance of a 23 Degree Conical-diffuser-tail-pipe Combination

    NASA Technical Reports Server (NTRS)

    Persh, Jerome

    1950-01-01

    An investigation was conducted to determine the effect of the inlet Mach number and entrance-boundary-layer thickness on the performance of a 23 degree 21-inch conical-diffuser - tail-pipe combination with a 2:1 area ratio. The air flows used in this investigation covered an inlet Mach number range from 0.17 to 0.89 and corresponding Reynolds numbers of 1,700,000 to 7,070,000. Results are reported for two inlet-boundary-layer thicknesses. Over the entire range of flows, the mean value of the inlet displacement thickness is about 0.034 inch for the thinner inlet boundary layer and about 0.170 inch for the case of the thicker inlet boundary layer. The performance of the diffuser - tail-pipe combination is presented together with examples of longitudinal static-pressure distribution and the results of boundary-layer pressure surveys made at six points along the diffuser wall. The results indicated a progressive diminution of the static-pressure recovery and a steady increase in the total-pressure losses as the inlet Mach number was increased for both inlet-boundary-layer thicknesses. The ratio of actual static-pressure rise to that theoretically possible was much less and the total-pressure losses were greater for the case of the thicker inlet boundary layer throughout the speed range investigated. With the thinner inlet boundary layer, flow separation occurred at the diffuser exit at all inlet Mach numbers.Unseparated flow alternating with separated flow was observed near the inlet at the higher velocities. For the case of the thicker inlet boundary layer, the origin of the separated region occurred in the vicinity of the inlet-duct-diffuser junction section at all Mach numbers.

  18. Thickness-dependent crystallization on thermal anneal for titania/silica nm-layer composites deposited by ion beam sputter method.

    PubMed

    Pan, Huang-Wei; Wang, Shun-Jin; Kuo, Ling-Chi; Chao, Shiuh; Principe, Maria; Pinto, Innocenzo M; DeSalvo, Riccardo

    2014-12-01

    Crystallization following thermal annealing of thin film stacks consisting of alternating nm-thick titania/silica layers was investigated. Several prototypes were designed, featuring a different number of titania/silica layer pairs, and different thicknesses (in the range from 4 to 40 nm, for the titania layers), but the same nominal refractive index (2.09) and optical thickness (a quarter of wavelength at 1064 nm). The prototypes were deposited by ion beam sputtering on silicon substrates. All prototypes were found to be amorphous as-deposited. Thermal annealing in air at progressive temperatures was subsequently performed. It was found that the titania layers eventually crystallized forming the anatase phase, while the silica layers remained always amorphous. However, progressively thinner layers exhibited progressively higher threshold temperatures for crystallization onset. Accordingly it can be expected that composites with thinner layers will be able to sustain higher annealing temperatures without crystallizing, and likely yielding better optical and mechanical properties for advanced coatings application. These results open the way to the use of materials like titania and hafnia, that crystallize easily under thermal anneal, but ARE otherwise promising candidate materials for HR coatings necessary for cryogenic 3rd generation laser interferometric gravitational wave detectors. PMID:25606914

  19. Geophysical Investigations on Malta (Central Mediterranean) using Ambient Noise: Assessing Array Performance and Influence of a Thick Low Velocity Layer.

    NASA Astrophysics Data System (ADS)

    Farrugia, D.; Paolucci, E.; D'Amico, S.; Galea, P. M.

    2014-12-01

    The use of microtremors to obtain shear wave velocity (Vs) profiles of the subsurface is becoming a widespread approach due to its various advantages. Noise measurements were carried out at four sites on Malta (Central Mediterranean). Array techniques were first tested in an area where a ≈45 m layer of soft Blue Clay (BC) overlies the harder limestone. Three array configurations (two arrays of 17 geophones in an L-shape and circle respectively and one 42 geophone array in an L-shape) were tested and processed using the f-k and two SPAC techniques: Modified and Extended SPAC. No significant difference was observed in the dispersion curve from the two short arrays despite having different shapes. However, a significant variation was observed between the dispersion curve from the long and short arrays in the low frequency part. A joint inversion, using two direct search methods, of the dispersion and the H/V curve was then used to obtain the Vs profile for the site, with most of the profiles being in agreement both in terms of velocity and depth. A study was also conducted at three other sites on Malta where hard Upper Coralline Limestone (UCL) overlies the soft BC creating a velocity inversion in the soil profile. The shape of the effective dispersion curves obtained using ESAC show both an inverse dispersive trend and normal dispersion. This shape is tentatively explained in terms of the presence of higher mode Rayleigh waves. A Genetic Algorithm approach was then used to jointly invert the H/V and Rayleigh wave dispersion curve. It was observed that the BC velocity was higher when overlain by a large thickness of UCL. This could be linked to the effective pressure caused by the hard UCL, making the BC more compact, and having a higher velocity. The theoretical implications of a prominent low-velocity layer on site amplification and the interpretation of ambient noise data are investigated and discussed.

  20. Effects of the Buffer Layers on the Adhesion and Antimicrobial Properties of the Amorphous ZrAlNiCuSi Films

    NASA Astrophysics Data System (ADS)

    Chiang, Pai-Tsung; Chen, Guo-Ju; Jian, Sheng-Rui; Shih, Yung-Hui

    2011-06-01

    To extend the practical applications of the bulk metallic glasses (BMGs), the preparation of the metallic glass coatings on various substrates becomes an important research issue. Among the interfacial properties of the coatings, the adhesion between films and substrates is the most crucial. In this study, amorphous Zr61Al7.5Ni10Cu17.5Si4 (ZrAlNiCuSi) thin films were deposited on SUS304 stainless steel at various sputtering powers by DC sputtering. According to the scratch tests, the introduction of the Cr and Ti buffer layers effectively improves the adhesion between the amorphous thin films and substrate without changing the surface properties, such as roughness and morphology. The antimicrobial results show that the biological activities of these microbes, except Acinetobacter baumannii, are effectively suppressed during the test period.

  1. Effect of Layer Thickness and Printing Orientation on Mechanical Properties and Dimensional Accuracy of 3D Printed Porous Samples for Bone Tissue Engineering

    PubMed Central

    Farzadi, Arghavan; Solati-Hashjin, Mehran; Asadi-Eydivand, Mitra; Abu Osman, Noor Azuan

    2014-01-01

    Powder-based inkjet 3D printing method is one of the most attractive solid free form techniques. It involves a sequential layering process through which 3D porous scaffolds can be directly produced from computer-generated models. 3D printed products' quality are controlled by the optimal build parameters. In this study, Calcium Sulfate based powders were used for porous scaffolds fabrication. The printed scaffolds of 0.8 mm pore size, with different layer thickness and printing orientation, were subjected to the depowdering step. The effects of four layer thicknesses and printing orientations, (parallel to X, Y and Z), on the physical and mechanical properties of printed scaffolds were investigated. It was observed that the compressive strength, toughness and Young's modulus of samples with 0.1125 and 0.125 mm layer thickness were more than others. Furthermore, the results of SEM and μCT analyses showed that samples with 0.1125 mm layer thickness printed in X direction have more dimensional accuracy and significantly close to CAD software based designs with predefined pore size, porosity and pore interconnectivity. PMID:25233468

  2. Optical and structural characteristics of high indium content InGaN/GaN multi-quantum wells with varying GaN cap layer thickness

    SciTech Connect

    Yang, J.; Zhao, D. G. Jiang, D. S.; Chen, P.; Zhu, J. J.; Liu, Z. S.; Le, L. C.; Li, X. J.; He, X. G.; Liu, J. P.; Yang, H.; Zhang, Y. T.; Du, G. T.

    2015-02-07

    The optical and structural properties of InGaN/GaN multi-quantum wells (MQWs) with different thicknesses of low temperature grown GaN cap layers are investigated. It is found that the MQW emission energy red-shifts and the peak intensity decreases with increasing GaN cap layer thickness, which may be partly caused by increased floating indium atoms accumulated at quantum well (QW) surface. They will result in the increased interface roughness, higher defect density, and even lead to a thermal degradation of QW layers. An extra growth interruption introduced before the growth of GaN cap layer can help with evaporating the floating indium atoms, and therefore is an effective method to improve the optical properties of high indium content InGaN/GaN MQWs.

  3. Surface photovoltage and photoluminescence study of thick Ga(In)AsN layers grown by liquid-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Donchev, V.; Milanova, M.; Lemieux, J.; Shtinkov, N.; Ivanov, I. G.

    2016-03-01

    We present an experimental and theoretical study of Ga(In)AsN layers with a thickness of around 1 μm grown by liquid-phase epitaxy (LPE) on n-type GaAs substrates. The samples are studied by surface photovoltage (SPV) spectroscopy and by photoluminescence spectroscopy. Th