Transition from moving to stationary double layers in a single-ended Q machine

NASA Technical Reports Server (NTRS)

Song, Bin; Merlino, R. L.; D'Angelo, N.

1990-01-01

Large-amplitude (less than about 100 percent) relaxation oscillations in the plasma potential are known to be generated when the cold endplate of a single-ended Q machine is biased positively. These oscillations are associated with double layers that form near the hot plate (plasma source) and travel toward the endplate at about the ion-acoustic velocity. At the endplate they dissolve and then form again near the hot plate, the entire process repeating itself in a regular manner. By admitting a sufficient amount of neutral gas into the system, the moving double layers were slowed down and eventually stopped. The production of stationary double layers requires an ion source on the high-potential side of the double layers. These ions are provided by ionization of the neutral gas by electrons that are accelerated through the double layer. The dependence of the critical neutral gas pressure required for stationary double-layer formation on endplate voltage, magnetic field strength, and neutral atom mass has been examined. These results are discussed in terms of a simple model of ion production and loss, including ion losses across the magnetic field.

Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

NASA Technical Reports Server (NTRS)

Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

1999-01-01

Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

Jet Formation and Penetration Study of Double-Layer Shaped Charge

NASA Astrophysics Data System (ADS)

Wang, Zhe; Jiang, Jian-Wei; Wang, Shu-You; Liu, Han

2018-04-01

A theoretical analysis on detonation wave propagation in a double-layer shaped charge (DLSC) is performed. Numerical simulations using the AUTODYN software are carried out to compare the distinctions between jet formations in DLSC and ordinary shaped charge (OSC), in particular, the OSC made using a higher detonation velocity explosive, which is treated as the outer layer charge in the DLSC. The results show that the improved detonation velocity ratio and radial charge percentage of outer-to-inner layer charge are conducive to the formation of a convergent detonation wave, which contributes to enhancement of jet tip velocity in DLSC. The thickness and mass percentages of liner flowing into jet in DLSC closely follow the exponential distribution along the radial direction, but the percentages in DLSC and the mass of effective jet, which have significant influence on the penetration depth, are lower than those in OSC with the outer layer charge. This implies that the total charge energy is the major factor controlling the effective jet formation, which is confirmed by the verification tests using flash X-ray system and following penetration tests. The numerical simulation and test results compare well, while penetration test results indicate that the performance of DLSC is not better than that of OSC with the outer layer charge, due to the differences in jet formation.

Space confinement and rotation stress induced self-organization of double-helix nanostructure: a nanotube twist with a moving catalyst head.

PubMed

Zhao, Meng-Qiang; Zhang, Qiang; Tian, Gui-Li; Huang, Jia-Qi; Wei, Fei

2012-05-22

Inorganic materials with double-helix structure have attracted intensive attention due to not only their elegant morphology but also their amazing morphology-related potential applications. The investigation on the formation mechanism of the inorganic double-helix nanostructure is the first step for the fundamental studies of their materials or physical properties. Herein, we demonstrated the space confinement and rotation stress induced self-organization mechanism of the carbon nanotube (CNT)-array double helices under scanning electron microscopy by directly observing their formation process from individual layered double hydroxide flakes, which is a kind of hydrotalcite-like material composed of positively charged layers and charge-balancing interlayer anions. Space confinement is considered to be the most important extrinsic factor for the formation of CNT-array double helices. Synchronous growth of the CNT arrays oppositely from LDH flakes with space confinement on both sides at the same time is essential for the growth of CNT-array double helices. Coiling of the as-grown CNT arrays into double helices will proceed by self-organization, tending to the most stable morphology in order to release their internal rotation stress. Based on the demonstrated mechanism, effective routes were carried out to improve the selectivity for CNT-array double helices. The work provides a promising method for the fabrication of double-helix nanostructures with their two helices connected at the end by self-assembly.

Kinetics of the electric double layer formation modelled by the finite difference method

NASA Astrophysics Data System (ADS)

Valent, Ivan

2017-11-01

Dynamics of the elctric double layer formation in 100 mM NaCl solution for sudden potentail steps of 10 and 20 mV was simulated using the Poisson-Nernst-Planck theory and VLUGR2 solver for partial differential equations. The used approach was verified by comparing the obtained steady-state solution with the available exact solution. The simulations allowed for detailed analysis of the relaxation processes of the individual ions and the electric potential. Some computational aspects of the problem were discussed.

Experimental Study of Acid Treatment Toward Characterization of Structural, Optical, and Morphological Properties of TiO2-SnO2 Composite Thin Film

NASA Astrophysics Data System (ADS)

Fajar, M. N.; Hidayat, R.; Triwikantoro; Endarko

2018-04-01

The TiO2-SnO2 thin film with single and double-layer structure has successfully synthesized on FTO (Fluorine-doped Tin Oxide) substrate using the screen printing technique. The structural, optical, and morphological properties of the film were investigated by XRD, UV-Vis, and SEM, respectively. The results showed that the single and double-layer structure of TiO2-SnO2 thin film has mixed phase with a strong formation of casseritte phase. The acid treatment effect on TiO2-SnO2 thin film decreases the peak intensity of anatase phase formation and thin film’s absorbance values. The morphological study is also revealed that the single layer TiO2-SnO2 thin film had a more porous nature and decreased particle size distribution after acid treatment, while the double-layer TiO2-SnO2 thin film Eroded due to acid treatment.

Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Tien, Chien-Pin; Teng, Hsisheng

A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a "dry" gel-electrolyte system a double layer capacitance as high as 130 F g -1. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices.

Theory of the formation of the electric double layer at the ion exchange membrane-solution interface.

PubMed

Moya, A A

2015-02-21

This work aims to extend the study of the formation of the electric double layer at the interface defined by a solution and an ion-exchange membrane on the basis of the Nernst-Planck and Poisson equations, including different values of the counter-ion diffusion coefficient and the dielectric constant in the solution and membrane phases. The network simulation method is used to obtain the time evolution of the electric potential, the displacement electric vector, the electric charge density and the ionic concentrations at the interface between a binary electrolyte solution and a cation-exchange membrane with total co-ion exclusion. The numerical results for the temporal evolution of the interfacial electric potential and the surface electric charge are compared with analytical solutions derived in the limit of the shortest times by considering the Poisson equation for a simple cationic diffusion process. The steady-state results are justified from the Gouy-Chapman theory for the diffuse double layer in the limits of similar and high bathing ionic concentrations with respect to the fixed-charge concentration inside the membrane. Interesting new physical insights arise from the interpretation of the process of the formation of the electric double layer at the ion exchange membrane-solution interface on the basis of a membrane model with total co-ion exclusion.

Ion-acoustic double-layers in a magnetized plasma with nonthermal electrons

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

Rios, L. A.; Galvão, R. M. O.; Instituto de Física, Universidade de São Paulo, 05508-900 São Paulo

2013-11-15

In the present work we investigate the existence of obliquely propagating ion-acoustic double layers in magnetized two-electron plasmas. The fluid model is used to describe the ion dynamics, and the hot electron population is modeled via a κ distribution function, which has been proved to be appropriate for modeling non-Maxwellian plasmas. A quasineutral condition is assumed to investigate these nonlinear structures, which leads to the formation of double-layers propagating with slow ion-acoustic velocity. The problem is investigated numerically, and the influence of parameters such as nonthermality is discussed.

The Influence of Multiple Nested Layer Waviness on the Compression Strength of Double Nested Wave Formations in a Carbon Fiber Composite Laminate

NASA Astrophysics Data System (ADS)

Khan, Z. M.; Adams, D. O.; Anas, S.

2016-01-01

As advanced composite materials having superior physical and mechanical properties are being developed, the optimization of their processing techniques is eagerly sought. One of the most common defects arising during processing of structural composites is layer waviness. The layer waviness is more pronounced in thick-section flat and cylindrical laminates, which are extensively used in large wind turbine blades, submersibles, and space platforms. The layer waviness undulates the entire layer of a multidirectional laminate in the throughthe-thickness direction, leading to a gross deterioration of its compressive strength. This research investigates the influence of multiple layer waviness in a double nest formation on the compression strength of a composite laminate. Different wave fractions of wavy 0° layers were fabricated in an IM/8551-7 carbon-epoxy composite laminate on a steel mold by using a single-step fabrication procedure. The test laminates were cured on a heated press according to the specific curing cycle of epoxy. Their static compression testing was performed using a NASA short block compression fixture on an MTS servohydraulic machine. The purpose of these tests was to determine the effects of multiple layer wave regions on the compression strength of the composite laminate. The experimental and analytical results obtained revealed that the reduction in the compression strength of composite laminate was constant after the fraction of the wavy 0° layers exceeded 35%. This analysis indicated that the percentage of the 0° wavy layer may be used to estimate the reduction in the compression strength of a double nested wave formation in a composite laminate.

Longitudinal transvaginal ultrasound evaluation of cesarean scar niche incidence and depth in the first two years after single- or double-layer uterotomy closure: a randomized controlled trial.

PubMed

Bamberg, Christian; Hinkson, Larry; Dudenhausen, Joachim W; Bujak, Verena; Kalache, Karim D; Henrich, Wolfgang

2017-12-01

Cesarean deliveries are the most common abdominal surgery procedure globally, and the optimal way to suture the hysterotomy remains a matter of debate. The aim of this study was to assess the incidence of cesarean scar niches and the depth after single- or double-layer uterine closure. We performed a randomized controlled trial in which women were allocated to three uterotomy suture techniques: continuous single-layer unlocked, continuous locked single-layer, or double-layer sutures. Transvaginal ultrasound was performed six weeks and 6-24 months after cesarean delivery [Clinicaltrials.gov (NCT02338388)]. The study included 435 women. Six weeks after delivery, the incidence of niche was not significantly different between the groups (p = 0.52): 40% for single-layer unlocked, 32% for single-layer locked and 43% for double-layer sutures. The mean ± SD niche depths were 3.0 ± 1.4 mm for single-layer unlocked, 3.6 ± 1.7 mm for single-layer locked and 3.3 ± 1.3 mm for double-layer sutures (p = 1.0). There were no significant differences (p = 0.58) in niche incidence between the three groups at the second ultrasound follow up: 30% for single-layer unlocked, 23% for single-layer locked and 29% for double-layer sutures. The mean ± SD niche depth was 3.1 ± 1.5 mm after single-layer unlocked, 2.8 ± 1.5 mm after single-layer locked and 2.5 ± 1.2 mm after double-layer sutures (p = 0.61). There was a trend (p = 0.06) for the residual myometrium thickness to be thicker after double-layer repair at the long-term follow up. The incidence of cesarean scar niche formation and the niche depth was independent of the hysterotomy closure technique. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

Homogeneous double-layer amorphous Si-doped indium oxide thin-film transistors for control of turn-on voltage

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

Kizu, Takio, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Tsukagoshi, Kazuhito, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya

We fabricated homogeneous double-layer amorphous Si-doped indium oxide (ISO) thin-film transistors (TFTs) with an insulating ISO cap layer on top of a semiconducting ISO bottom channel layer. The homogeneously stacked ISO TFT exhibited high mobility (19.6 cm{sup 2}/V s) and normally-off characteristics after annealing in air. It exhibited normally-off characteristics because the ISO insulator suppressed oxygen desorption, which suppressed the formation of oxygen vacancies (V{sub O}) in the semiconducting ISO. Furthermore, we investigated the recovery of the double-layer ISO TFT, after a large negative shift in turn-on voltage caused by hydrogen annealing, by treating it with annealing in ozone. The recoverymore » in turn-on voltage indicates that the dense V{sub O} in the semiconducting ISO can be partially filled through the insulator ISO. Controlling molecule penetration in the homogeneous double layer is useful for adjusting the properties of TFTs in advanced oxide electronics.« less

Strategy for synthesizing quantum dot-layered double hydroxide nanocomposites and their enhanced photoluminescence and photostability.

PubMed

Cho, Seungho; Jung, Sungwook; Jeong, Sanghwa; Bang, Jiwon; Park, Joonhyuck; Park, Youngrong; Kim, Sungjee

2013-01-08

Layered double hydroxide-quantum dot (LDH-QD) composites are synthesized via a room temperature LDH formation reaction in the presence of QDs. InP/ZnS (core/shell) QD, a heavy metal free QD, is used as a model constituent. Interactions between QDs (with negative zeta potentials), decorated with dihydrolipoic acids, and inherently positively charged metal hydroxide layers of LDH during the LDH formations are induced to form the LDH-QD composites. The formation of the LDH-QD composites affords significantly enhanced photoluminescence quantum yields and thermal- and photostabilities compared to their QD counterparts. In addition, the fluorescence from the solid LDH-QD composite preserved the initial optical properties of the QD colloid solution without noticeable deteriorations such as red-shift or deep trap emission. Based on their advantageous optical properties, we also demonstrate the pseudo white light emitting diode, down-converted by the LDH-QD composites.

Two-dimensional quasi-double-layers in two-electron-temperature, current-free plasmas

NASA Astrophysics Data System (ADS)

Merino, Mario; Ahedo, Eduardo

2013-02-01

The expansion of a plasma with two disparate electron populations into vacuum and channeled by a divergent magnetic nozzle is analyzed with an axisymmetric model. The purpose is to study the formation and two-dimensional shape of a current-free double-layer in the case when the electric potential steepening can still be treated within the quasineutral approximation. The properties of this quasi-double-layer are investigated in terms of the relative fraction of the high-energy electron population, its radial distribution when injected into the nozzle, and the geometry and intensity of the applied magnetic field. The two-dimensional double layer presents a curved shape, which is dependent on the natural curvature of the equipotential lines in a magnetically expanded plasma and the particular radial distribution of high-energy electrons at injection. The double layer curvature increases the higher the nozzle divergence is, the lower the magnetic strength is, and the more peripherally hot electrons are injected. A central application of the study is the operation of a helicon plasma thruster in space. To this respect, it is shown that the curvature of the double layer does not increment the thrust, it does not modify appreciably the downstream divergence of the plasma beam, but it increases the magnetic-to-pressure thrust ratio. The present study does not attempt to cover current-free double layers involving plasmas with multiple populations of positive ions.

Experimental investigation of current free double layers in helicon plasmas

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

Sahu, B. B.; Tarey, R. D.; Ganguli, A.

2014-02-15

The paper presents investigations of current free double layer (CFDL) that forms in helicon plasmas. In contrast to the other work reporting on the same subject, in the present investigations the double layer (DL) forms in a mirror-like magnetic field topology. The RF compensated Langmuir probe measurements show multiple DLs, which are in connection with, the abrupt fall of densities along with potential drop of about 24 V and 18 V. The DLs strengths (e ΔV{sub p})/(k T{sub e}) are about 9.5 and 6, and the corresponding widths are about 6 and 5 D lengths. The potential drop is nearly equal tomore » the thermal anisotropies between the two plasma regions forming the DL, which is present in the plateau region of mirror, unlike the earlier studies on the DL formation in the region of strong gradients in the magnetic field. Also, it presents a qualitative discussion on the mechanism of DL formation.« less

Double-layered cell transfer technology for bone regeneration

PubMed Central

Akazawa, Keiko; Iwasaki, Kengo; Nagata, Mizuki; Yokoyama, Naoki; Ayame, Hirohito; Yamaki, Kazumasa; Tanaka, Yuichi; Honda, Izumi; Morioka, Chikako; Kimura, Tsuyoshi; Komaki, Motohiro; Kishida, Akio; Izumi, Yuichi; Morita, Ikuo

2016-01-01

For cell-based medicine, to mimic in vivo cellular localization, various tissue engineering approaches have been studied to obtain a desirable arrangement of cells on scaffold materials. We have developed a novel method of cell manipulation called “cell transfer technology”, enabling the transfer of cultured cells onto scaffold materials, and controlling cell topology. Here we show that using this technique, two different cell types can be transferred onto a scaffold surface as stable double layers or in patterned arrangements. Various combinations of adherent cells were transferred to a scaffold, amniotic membrane, in overlapping bilayers (double-layered cell transfer), and transferred cells showed stability upon deformations of the material including folding and trimming. Transplantation of mesenchymal stem cells from periodontal ligaments (PDLSC) and osteoblasts, using double-layered cell transfer significantly enhanced bone formation, when compared to single cell type transplantation. Our findings suggest that this double-layer cell transfer is useful to produce a cell transplantation material that can bear two cell layers. Moreover, the transplantation of an amniotic membrane with PDLSCs/osteoblasts by cell transfer technology has therapeutic potential for bone defects. We conclude that cell transfer technology provides a novel and unique cell transplantation method for bone regeneration. PMID:27624174

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer.

PubMed

Zhang, Zhaojing; Yao, Liyong; Zhang, Yi; Ao, Jianping; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming-Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2018-02-01

Double layer distribution exists in Cu 2 SnZnSe 4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double-layer distribution of CZTSe film is eliminated entirely and the formation of MoSe 2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSe x mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu-Sn-Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu 2 Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe 2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm 2 and a CZTSe solar cell with efficiency of 7.2% is fabricated.

Coexistence of bipolar and unipolar resistive switching behaviors in the double-layer Ag/ZnS-Ag/CuAlO2/Pt memory device

NASA Astrophysics Data System (ADS)

Zhang, Lei; Xu, Haiyang; Wang, Zhongqiang; Yu, Hao; Ma, Jiangang; Liu, Yichun

2016-01-01

The coexistence of uniform bipolar and unipolar resistive-switching (RS) characteristics was demonstrated in a double-layer Ag/ZnS-Ag/CuAlO2/Pt memory device. By changing the compliance current (CC) from 1 mA to 10 mA, the RS behavior can be converted from the bipolar mode (BRS) to the unipolar mode (URS). The temperature dependence of low resistance states further indicates that the CFs are composed of the Ag atoms and Cu vacancies for the BRS mode and URS mode, respectively. For this double-layer structure device, the thicker conducting filaments (CFs) will be formed in the ZnS-Ag layer, and it can act as tip electrodes. Thus, the formation and rupture of these two different CFs are located in the CuAlO2 layer, realizing the uniform and stable BRS and URS.

Facile synthesis of 3D MnNi-layered double hydroxides (LDH)/graphene composites from directly graphites for pseudocapacitor and their electrochemical analysis

NASA Astrophysics Data System (ADS)

Lee, Ilbok; Jeong, Gyoung Hwa; An, Soyeon; Kim, Sang-Wook; Yoon, Songhun

2018-01-01

Herein, MnNi-layered double hydroxides (LDH) were imbibed within the interlayers of graphene nanosheets. The anionic surfactant, sodium dodecyl sulfate played a role of graphite exfoliator adding interaction with metal cations. Using this process, layered MnNi-LDH-graphene nanocomposite was prepared without formation of graphene oxide. When applied into pseudocapacitor electrode, LDH-graphene with optimal ratio between Mn and Ni exhibited very stable cycle with 90% at 1400 cycles and high energy 47.29 Wh kg-1 at the power density of 7473 W kg-1, which was attributed to highly stable layered LDH structure within conductive graphene layers.

POE/PLGA composite microspheres: formation and in vitro behavior of double walled microspheres.

PubMed

Yang, Yi-Yan; Shi, Meng; Goh, Suat-Hong; Moochhala, Shabbir M; Ng, Steve; Heller, Jorge

2003-03-07

The poly(ortho ester) (POE) and poly(D,L-lactide-co-glycolide) 50:50 (PLGA) composite microspheres were fabricated by a water-in-oil-in-water (w/o/w) double emulsion process. The morphology of the composite microspheres varied depending on POE content. When the POE content was 50, 60 or 70% in weight, the double walled microspheres with a dense core of POE and a porous shell of PLGA were formed. The formation of the double walled POE/PLGA microspheres was analysed. Their in vitro degradation behavior was characterized by scanning electron microscopy, gel permeation chromatography, Fourier-transform infrared microscopy and nuclear magnetic resonance spectroscopy (NMR). It was found that compared to the neat POE or PLGA microspheres, distinct degradation mechanism was achieved in the double walled POE/PLGA microspheres system. The degradation of the POE core was accelerated due to the acidic microenvironment produced by the hydrolysis of the outer PLGA layer. The formation of hollow microspheres became pronounced after the first week in vitro. 1H NMR spectra showed that the POE core was completely degraded after 4 weeks. On the other hand, the outer PLGA layer experienced slightly retarded degradation after the POE core disappeared. PLGA in the double walled microspheres kept more than 32% of its initial molecular weight over a period of 7 weeks.

Dynamics of spallation during femtosecond laser ablation studied by time-resolved reflectivity with double pump pulses

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

Kumada, Takayuki, E-mail: kumada.takayuki@jaea.go.jp; Otobe, Tomohito; Nishikino, Masaharu

2016-01-04

The dynamics of photomechanical spallation during femtosecond laser ablation of fused silica was studied by time-resolved reflectivity with double pump pulses. Oscillation of reflectivity was caused by interference between the probe pulses reflected at the sample surface and the spallation layer, and was enhanced when the surface was irradiated with the second pump pulse within a time interval, Δτ, of several picoseconds after the first pump pulse. However, as Δτ was increased, the oscillation amplitude decreased with an exponential decay time of 10 ps. The oscillation disappeared when Δτ exceeded 20 ps. This result suggests that the formation time of the spallationmore » layer is approximately 10 ps. A second pump pulse with Δτ shorter than 10 ps excites the bulk sample. The spallation layer that is photo-excited by the first and second pump pulses is separated afterward. In contrast, a pulse with Δτ longer than the formation time excites and breaks up the spallation layer that has already been separated from the bulk. The formation time of the spallation layer, as determined in this experiment, is attributed to the characteristic time of the mechanical equilibration corresponding to the thickness divided by the sound velocity of the photo-excited layer.« less

Emergence of a Stern Layer from the Incorporation of Hydration Interactions into the Gouy-Chapman Model of the Electrical Double Layer.

PubMed

Brown, Matthew A; Bossa, Guilherme Volpe; May, Sylvio

2015-10-27

In one of the most commonly used phenomenological descriptions of the electrical double layer, a charged solid surface and a diffuse region of mobile ions are separated from each other by a thin charge-depleted Stern layer. The Stern layer acts as a capacitor that improves the classical Gouy-Chapman model by increasing the magnitude of the surface potential and limiting the maximal counterion concentration. We show that very similar Stern-like properties of the diffuse double layer emerge naturally from adding a nonelectrostatic hydration repulsion to the electrostatic Coulomb potential. The interplay of electrostatic attraction and hydration repulsion of the counterions and the surface leads to the formation of a diffuse counterion layer that remains well separated from the surface. In addition, hydration repulsions between the ions limit and control the maximal ion concentration and widen the width of the diffuse double layer. Our mean-field model, which we express in terms of electrostatic and hydration potentials, is physically consistent and conceptually similar to the classical Gouy-Chapman model. It allows the incorporation of ion specificity, accounts for hydration properties of charged surfaces, and predicts Stern layer properties, which we analyze in terms of the effective size of the hydrated counterions.

Effect of Induced Charge Electroosmosis on the Dielectrophoretic Motion of Particles

NASA Astrophysics Data System (ADS)

Swaminathan, T.; Hu, Howard

2006-11-01

Most suspensions involve the formation of ionic double layers next to the surface of particles due to the induced-charge on the surface. These double layers affect the motion of the particle even under AC electric fields. They modify the net dipole moment of the particle and at the same time produce slip velocities on the surfaces of these particles. A method to numerically evaluate the effect of the double layer on the dielectrophoretic motion of particles has been previously developed to study these two effects. The technique involves a matched asymptotic expansion of the electric field near the particle surface, where the double layer is formed, and is written as a jump-boundary-condition for the electric potential when the thickness of the double layer is small compared to the size of the particle. The developed jump-boundary-condition is then used to calculate an effective zeta potential on the particle surface. Unlike classical electroosmosis, this zeta potential is no longer constant on every part of the surface and is dependent on the applied electric field. The effect of the induced-charge electroosmotic slip velocity on the dielectrophoretic motion of particles has been observed using this technique.

Reversible Heating in Electric Double Layer Capacitors

NASA Astrophysics Data System (ADS)

Janssen, Mathijs; van Roij, René

2017-03-01

A detailed comparison is made between different viewpoints on reversible heating in electric double layer capacitors. We show in the limit of slow charging that a combined Poisson-Nernst-Planck and heat equation, first studied by d'Entremont and Pilon [J. Power Sources 246, 887 (2014), 10.1016/j.jpowsour.2013.08.024], recovers the temperature changes as predicted by the thermodynamic identity of Janssen et al. [Phys. Rev. Lett. 113, 268501 (2014), 10.1103/PhysRevLett.113.268501], and disagrees with the approximative model of Schiffer et al. [J. Power Sources 160, 765 (2006), 10.1016/j.jpowsour.2005.12.070] that predominates the literature. The thermal response to the adiabatic charging of supercapacitors contains information on electric double layer formation that has remained largely unexplored.

Water transport and desalination through double-layer graphyne membranes.

PubMed

Akhavan, Mojdeh; Schofield, Jeremy; Jalili, Seifollah

2018-05-16

Non-equilibrium molecular dynamics simulations of water-salt solutions driven through single and double-layer graphyne membranes by a pressure difference created by rigid pistons are carried out to determine the relative performance of the membranes as filters in a reverse osmosis desalination process. It is found that the flow rate of water through a graphyne-4 membrane is twice that of a graphyne-3 membrane for both single and double-layer membranes. Although the addition of a second layer to a single-layer membrane reduces the membrane permeability, the double-layer graphyne membranes are still two or three orders of magnitude more permeable than commercial reverse osmosis membranes. The minimum reduction in flow rate for double-layer membranes occurs at a layer spacing of 0.35 nm with an AA stacking configuration, while at a spacing of 0.6 nm the flow rate is close to zero due to a high free energy barrier for permeation. This is caused by the difference in the environments on either side of the membrane sheets and the formation of a compact two-dimensional layer of water molecules in the interlayer space which slows down water permeation. The distribution of residence times of water molecules in the interlayer region suggests that at the critical layer spacing of 0.6 nm, a cross-over occurs in the mechanism of water flow from the collective movement of hydrogen-bonded water sheets to the permeation of individual water molecules. All membranes are demonstrated to have a high salt rejection fraction and the double-layered graphyne-4 membranes can further increase the salt rejection by trapping ions that have passed through the first membrane from the feed solution in the interlayer space.

Electrical Double Layer Capacitance in a Graphene-embedded Al2O3 Gate Dielectric

PubMed Central

Ki Min, Bok; Kim, Seong K.; Jun Kim, Seong; Ho Kim, Sung; Kang, Min-A; Park, Chong-Yun; Song, Wooseok; Myung, Sung; Lim, Jongsun; An, Ki-Seok

2015-01-01

Graphene heterostructures are of considerable interest as a new class of electronic devices with exceptional performance in a broad range of applications has been realized. Here, we propose a graphene-embedded Al2O3 gate dielectric with a relatively high dielectric constant of 15.5, which is about 2 times that of Al2O3, having a low leakage current with insertion of tri-layer graphene. In this system, the enhanced capacitance of the hybrid structure can be understood by the formation of a space charge layer at the graphene/Al2O3 interface. The electrical properties of the interface can be further explained by the electrical double layer (EDL) model dominated by the diffuse layer. PMID:26530817

Laboratory layered latte.

PubMed

Xue, Nan; Khodaparast, Sepideh; Zhu, Lailai; Nunes, Janine K; Kim, Hyoungsoo; Stone, Howard A

2017-12-12

Inducing thermal gradients in fluid systems with initial, well-defined density gradients results in the formation of distinct layered patterns, such as those observed in the ocean due to double-diffusive convection. In contrast, layered composite fluids are sometimes observed in confined systems of rather chaotic initial states, for example, lattes formed by pouring espresso into a glass of warm milk. Here, we report controlled experiments injecting a fluid into a miscible phase and show that, above a critical injection velocity, layering emerges over a time scale of minutes. We identify critical conditions to produce the layering, and relate the results quantitatively to double-diffusive convection. Based on this understanding, we show how to employ this single-step process to produce layered structures in soft materials, where the local elastic properties vary step-wise along the length of the material.

On the modulation of the Jovian decametric radiation by Io. I - Acceleration of charged particles

NASA Technical Reports Server (NTRS)

Smith, R. A.; Goertz, C. K.

1978-01-01

A steady-state analysis of the current circuit between Io and the Jovian ionosphere is performed, assuming that the current is carried by electrons accelerated through potential double layers in the Io flux tube. The circuit analysis indicates that electrons may be accelerated up to energies of several hundred keV. Several problems associated with the formation of double layers are also discussed. The parallel potential drops decouple the flux tube from the satellite's orbital motion.

Superfluidity of dipolar excitons in a transition metal dichalcogenide double layer

NASA Astrophysics Data System (ADS)

Berman, Oleg L.; Kezerashvili, Roman Ya.

2017-09-01

We study formation and superfluidity of dipolar excitons in double layer heterostructures formed by two transition metal dichalcogenide (TMDC) atomically thin layers. Considering screening effects for an electron-hole interaction via the harmonic oscillator approximation for the Keldysh potential, the analytical expressions for the exciton energy spectrum and the mean field critical temperature Tc for the superfluidity are obtained. It is shown that binding energies of A excitons are larger than for B excitons. The mean field critical temperature for a two-component dilute exciton system in a TMDC double layer is analyzed and shown that the latter is an increasing function of the factor Q , determined by the effective masses of A and B excitons and their reduced mass. Comparison of the calculations for Tc performed by employing the Coulomb and Keldysh interactions demonstrates the importance of screening effects in TMDC.

Reversible Heating in Electric Double Layer Capacitors.

PubMed

Janssen, Mathijs; van Roij, René

2017-03-03

A detailed comparison is made between different viewpoints on reversible heating in electric double layer capacitors. We show in the limit of slow charging that a combined Poisson-Nernst-Planck and heat equation, first studied by d'Entremont and Pilon [J. Power Sources 246, 887 (2014)JPSODZ0378-775310.1016/j.jpowsour.2013.08.024], recovers the temperature changes as predicted by the thermodynamic identity of Janssen et al. [Phys. Rev. Lett. 113, 268501 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.268501], and disagrees with the approximative model of Schiffer et al. [J. Power Sources 160, 765 (2006)JPSODZ0378-775310.1016/j.jpowsour.2005.12.070] that predominates the literature. The thermal response to the adiabatic charging of supercapacitors contains information on electric double layer formation that has remained largely unexplored.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer

PubMed Central

Zhang, Zhaojing; Yao, Liyong; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming‐Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2017-01-01

Abstract Double layer distribution exists in Cu2SnZnSe4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double‐layer distribution of CZTSe film is eliminated entirely and the formation of MoSe2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSex mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu‐Sn‐Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu2Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm2 and a CZTSe solar cell with efficiency of 7.2% is fabricated. PMID:29610727

A New Theory of Mix in Omega Capsule Implosions

NASA Astrophysics Data System (ADS)

Knoll, Dana; Chacon, Luis; Rauenzahn, Rick; Simakov, Andrei; Taitano, William; Welser-Sherrill, Leslie

2014-10-01

We put forth a new mix model that relies on the development of a charge-separation electrostatic double-layer at the fuel-pusher interface early in the implosion of an Omega plastic ablator capsule. The model predicts a sizable pusher mix (several atom %) into the fuel. The expected magnitude of the double-layer field is consistent with recent radial electric field measurements in Omega plastic ablator implosions. Our theory relies on two distinct physics mechanisms. First, and prior to shock breakout, the formation of a double layer at the fuel-pusher interface due to fast preheat-driven ionization. The double-layer electric field structure accelerates pusher ions fairly deep into the fuel. Second, after the double-layer mix has occurred, the inward-directed fuel velocity and temperature gradients behind the converging shock transports these pusher ions inward. We first discuss the foundations of this new mix theory. Next, we discuss our interpretation of the radial electric field measurements on Omega implosions. Then we discuss the second mechanism that is responsible for transporting the pusher material, already mixed via the double-layer deep into the fuel, on the shock convergence time scale. Finally we make a connection to recent mix motivated experimental data on. This work conducted under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory, managed by LANS, LLC under Contract DE-AC52-06NA25396.

Electrodynamics of frictional interaction in tribolink “metal-polymer”

NASA Astrophysics Data System (ADS)

Volchenko, N. A.; Krasin, P. S.; Volchenko, A. I.; Zhuravlev, D. Yu

2018-03-01

The materials of the article illustrate the estimation of the energy loading of a metal friction element in the metal-electrolyte-polymer friction pair while forming various types of double electrical layers with the release of its thermal stabilization state. The energy loading of the contact spots of the microprotrusions of the friction pairs of braking devices depends to a large extent on the electrical, thermal and chemical fields that are of a different nature to an allowable temperature and are above the surface layers of the polymer patch. The latter is significantly influenced by double electrical layers that are formed at the boundaries of the phases “metal-metal”, “metal-polymer”, “metal-semiconductor”, “semiconductor-semiconductor” and “metal-electrolyte”. When two electrically conducting phases come into contact with electrothermomechanical friction, a difference in electrical potentials arises, which is due to the formation of a double electric layer, that is an asymmetric distribution of charged particles near the phase boundary. The structure of the double electric layer does not matter for the magnitude of the reversible electrode potential, which is determined by the variation of the isobaric-isothermal potential of the corresponding electrochemical reaction.

Double-layer effects on the lifetime of newly developed HBC-foils for RCS of J-PARC

NASA Astrophysics Data System (ADS)

Sugai, I.; Takeda, Y.; Oyaizu, M.; Kawakami, H.; Irie, Y.; Takagi, A.; Hattori, H.; Kawasaki, K.

2010-02-01

We have developed hybrid type boron-mixed carbon (HBC) foils for the rapid cycling synchrotron (RCS) of Japan-proton accelerator research complex (J-PARC) using the controlled DC arc-discharge method. The method has been found suitable for the production of thick foils up to a maximum of 700 μg/cm 2 due to the strong adhesion to the substrate. The foils thus produced showed rather long lifetime. By the development, high-temperature damage (foil deformation, thickness reduction and pinhole formation) of the foil was significantly mitigated even at a temperature of approximately 1700 K. However, when the foil temperature was higher than about 1800 K, especially pinhole formation in the irradiated area of the foil and its peripheries were always observed. In order to relieve high-temperature damage, we investigated the possibility to lower the temperature rise in single and double layer HBC-foils while keeping the total thickness the same. We also compared the lifetime of the single and the double layer HBC-foils as well as diamond and commercially available foils, using a 3.2 MeV Ne + ion beam from the Van de Graaff accelerator.

Laser Induced Fluorescence Studies of Electrostatic Double Layers in an Expanding Helicon Plasma

NASA Astrophysics Data System (ADS)

Carr, Jerry, Jr.

We report the first evidence of a laboratory double layer (DL) collapsing in the presence of an instability studied by Chakraborty Thakur et al. 1 with the use of time resolved laser induced fluorescence (LIF) studies. Higher time resolution studies then provided the first statistically validated proof of the correlation between the ion acoustic instability and a DL. Time-frequency analysis in the form of time resolved cross power spectra and continuous wavelet transforms were used to provide insight into beam formation. The implications of this work is that in the creation of strong DLs in expanding plasmas for plasma propulsion or other applications may be self-limited through instability growth. Over the past decade, experimental and theoretical studies have demonstrated the formation of stable, electrostatic, current-free double layers (CFDLs) in plasmas with a strong density gradient; typically a result of a divergent magnetic field. In this work, we present evidence for the formation of multiple double layers within a single divergent magnetic field structure. Downstream of the divergent magnetic field, multiple accelerated ion populations are observed through laser induced fluorescence measurements of the ion velocity distribution function. The formation of the multiple double layer structure is a strong function of the neutral gas pressure in the experiment. The similarity of the accelerated ion populations observed in these laboratory experiments to ion populations observed in reconnection outflow regions in the magnetosphere and in numerical simulations is also described. If ion energization during magnetic reconnection also results solely from acceleration in electric fields, these observations imply a prediction that the ion heating, i.e., the broadening of ion velocity distribution functions, reported in magnetic reconnection experiments is more accurately described by a superposition of differently accelerated ion populations. Therefore, the ion gheatingh rate during reconnection should scale as the square root of the cube of the charge per unit mass (q3/m)1/2 for ions with varying charge-to-mass ratios. A new RFEA probe was benchmarked on the low pressure CFDL plasmas produced in WVU HELIX-LEIA. This work was the result of collaboration between the University of Tromso (UiT) and WVU. LIF was used to confirm the RFEAs ability to detect a beam when one was present. The RFEA was also able to detect the presence of a beam when LIF techniques were limited by metastable quenching. The probefs limitations in dealing with ion focusing are discussed as well.

The dynamics of layered and non-layered oscillatory double-diffusive convection

NASA Astrophysics Data System (ADS)

Moll, Ryan D.

Oscillatory double diffusive convection (ODDC) is a double diffusive instability that occurs in fluids that are unstably stratified in temperature and stably stratified in chemical composition. Regions unstable to ODDC are common in the interiors of stars and giant planets, and knowing thermal and compositional transport through these regions is important for stellar and planetary evolution models. Using 3D direct numerical simulations, Rosenblum et al. 2011 first showed that ODDC can either lead to the spontaneous formation of convective layers, or remain in a state dominated by large scale gravity waves. Subsequent studies focused on identifying the conditions for layer formation (Mirouh et al. 2012), and quantifying transport through layered systems (Wood et al. 2013). This document includes 3 works that build on the results of these earlier studies. The subject of the first is transport through non-layered ODDC and shows that in the absence of layered convection, ODDC is dominated by large scale gravity waves that grow to the size of the domain. We find that while these gravity waves induce small amounts of turbulent mixing, turbulent transport through non-layered systems is not significant for the purposes of astrophysical modeling (unlike in layered convection). The second study pertains to ODDC in the presence of Coriolis forces, and shows that rotating systems can be categorized depending on the strength of the rotation. We find that in the slowly rotating regime, the presence of rotation does not significantly affect qualitative behavior, but leads to modest reductions in thermal and compositional transport, while in the fast rotation regime qualitative behaviors are radically different, and systems are dominated by vortices that affect thermal and compositional transport in complex ways. In the final work we study simulations of ODDC at non-layered parameters that are forced into a layered configuration by initial conditions. Our results show that measurements of thermal and compositional transport deviate from values predicted by oft-cited geophysical transport laws.

Characterization and structural analysis of wild type and a non-abscission mutant at the development funiculus (Def) locus in Pisum sativum L.

PubMed

Ayeh, Kwadwo Owusu; Lee, YeonKyeong; Ambrose, Mike J; Hvoslef-Eide, Anne Kathrine

2009-06-23

In pea seeds (Pisum sativum L.), the Def locus defines an abscission event where the seed separates from the funicle through the intervening hilum region at maturity. A spontaneous mutation at this locus results in the seed failing to abscise from the funicle as occurs in wild type peas. In this work, structural differences between wild type peas that developed a distinct abscission zone (AZ) between the funicle and the seed coat and non-abscission def mutant were characterized. A clear abscission event was observed in wild type pea seeds that were associated with a distinct double palisade layers at the junction between the seed coat and funicle. Generally, mature seeds fully developed an AZ, which was not present in young wild type seeds. The AZ was formed exactly below the counter palisade layer. In contrast, the palisade layers at the junction of the seed coat and funicle were completely absent in the def mutant pea seeds and the cells in this region were seen to be extensions of surrounding parenchymatous cells. The Def wild type developed a distinct AZ associated with palisade layer and counterpalisade layer at the junction of the seed coat and funicle while the def mutant pea seed showed non-abscission and an absence of the double palisade layers in the same region. We conclude that the presence of the double palisade layer in the hilum of the wild type pea seeds plays an important structural role in AZ formation by delimiting the specific region between the seed coat and the funicle and may play a structural role in the AZ formation and subsequent detachment of the seed from the funicle.

A double layer model for solar X-ray and microwave pulsations

NASA Technical Reports Server (NTRS)

Tapping, K. F.

1986-01-01

The wide range of wavelengths over which quasi-periodic pulsations have been observed suggests that the mechanism causing them acts upon the supply of high energy electrons driving the emission processes. A model is described which is based upon the radial shrinkage of a magnetic flux tube. The concentration of the current, along with the reduction in the number of available charge carriers, can rise to a condition where the current demand exceeds the capacity of the thermal electrons. Driven by the large inductance of the external current circuit, an instability takes place in the tube throat, resulting in the formation of a potential double layer, which then accelerates electrons and ions to MeV energies. The double layer can be unstable, collapsing and reforming repeatedly. The resulting pulsed particle beams give rise to pulsating emission which are observed at radio and X-ray wavelengths.

Mechanochemical approach for synthesis of layered double hydroxides

NASA Astrophysics Data System (ADS)

Zhang, Xiaoqing; Li, Shuping

2013-06-01

In this paper, a mechanochemical approach is used to prepare layered double hydroxides (LDHs). This approach involves manually grinding the precursor, nitrates and then the hydrothermal treatment. The study indicates that grinding leads to the incomplete formation of LDHs phase, LDHs-M. The reaction degree of precursor salts to LDHs after grinding depends on the melting points of the precursors. As expected, hydrothermal treatment is beneficial for the good crystallization and regularity of LDHs. Especially, the effect of hydrothermal treatment has been emphatically explored. The hydration of LDHs-M, increment of zeta potentials and the complete exchange of NO3- by CO32- anions occur successively or in parallel during the hydrothermal treatment. It can be found that combination of grinding and hydrothermal treatment gives rise to the formation of uniform and monodispersed particles of LDHs.

Stability of excitons in double quantum well: Through electron and holes transmission probabilities

NASA Astrophysics Data System (ADS)

Vignesh, G.; Nithiananthi, P.

2017-05-01

Stability of excitons has been analyzed using the transmission probability of its constituent particles in GaAs/Al0.3Ga0.7As Double Quantum Well (DQW) structure by varying well and barrier layer thickness. The effective mass approximation is used and anisotropy in material properties are also considered to get realistic situations. It is observed that tuning barrier layer avails many resonance peaks for the transmission and tuning well width admits maximum transmission at narrow well widths. Every saddle point of the observed transmission coefficients decides the formation, strength and transportation of excitons in DQW.

Synthesis of nanometre-thick MoO3 sheets

NASA Astrophysics Data System (ADS)

Kalantar-Zadeh, Kourosh; Tang, Jianshi; Wang, Minsheng; Wang, Kang L.; Shailos, Alexandros; Galatsis, Kosmas; Kojima, Robert; Strong, Veronica; Lech, Andrew; Wlodarski, Wojtek; Kaner, Richard B.

2010-03-01

The formation of MoO3 sheets of nanoscale thickness is described. They are made from several fundamental sheets of orthorhombic α-MoO3, which can be processed in large quantities via a low cost synthesis route that combines thermal evaporation and mechanical exfoliation. These fundamental sheets consist of double-layers of linked distorted MoO6 octahedra. Atomic force microscopy (AFM) measurements show that the minimum resolvable thickness of these sheets is 1.4 nm which is equivalent to the thickness of two double-layers within one unit cell of the α-MoO3 crystal.

Successful new anti-sloughing drilling fluid application, Yanchang gas field, China

NASA Astrophysics Data System (ADS)

He, Peng; Liu, Hanmei; Du, Sen; He, Chenghai

2017-10-01

Borehole collapse had always been encountered when drilling the Shiqianfeng and Shihezi formations in Yan Chang gas field. By analyzing the reasons for the collapse can be obtained, "double layer of stone" brittle strong, pore development, water sensitivity and high mineral content filling skeleton particles, water lock effect and stress sensitivity is a potential factor in inducing strong wall collapse. According to the characteristics of the geological structure developed anti-sloughing drilling fluid system "double layer of stone," "complex fluid loss - dual inhibition - materialized block" multiple cooperative mechanism to achieve the purpose of anti-collapse.

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

Petersen, Line Boisen; Lipton, Andrew S.; Zorin, Vadim

Ordering of gallium(III) in a series of magnesium gallium (MgGa) layered double hydroxides (LDHs), [Mg{sub 1−x}Ga{sub x}(OH){sub 2}(NO{sub 3}){sub x}·yH{sub 2}O] was investigated using solid-state {sup 1}H and {sup 71}Ga NMR spectroscopy as well as powder X-ray diffraction. Three different proton environments from Mg{sub 3}-OH, Mg{sub 2}Ga-OH and intergallery water molecules were assigned and quantified using ({sup 1}H,{sup 71}Ga) HETCOR and {sup 1}H MAS NMR. A single {sup 71}Ga site originating from the unique Ga site in the MgGa LDH's was observed in {sup 71}Ga MAS and 3QMAS NMR spectra. Both {sup 1}H MAS NMR spectra recorded at 21.1 Tmore » (900 MHz) and elemental analysis show that the synthesized MgGa LDH's had a lower Mg:Ga ratio than that of the starting reactant solution. The origin of this is the formation of soluble [Ga(OH){sub 4}]{sup −} complexes formed during synthesis, and not due to formation of insoluble gallium (oxy)hydroxides. No sign of Ga-O-Ga connectivities or defects were detected for the MgGa LDH's. - Graphical abstract: Two types of hydroxides groups are observed in magnesium gallium layered double hydroxides revealing an ordering of Ga in the cation layer. - Highlights: • Ga is ordered in our magnesium gallium layered double hydroxides. • Ga depletion due to formation of soluble Ga complexes during synthesis. • No sign of Ga rich regions in magnesium gallium LDHs. • Solid state {sup 1}H and {sup 71}Ga give detailed insight into the structure.« less

Evidence of current free double layer in high density helicon discharge

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

Ganguli, A.; Sahu, B. B.; Tarey, R. D.

2013-01-15

This paper investigates the formation of double layer (DL) in helicon plasmas. In the experiment, argon plasma production is using the excitation of m = -1 helicon mode with magnetic mirror field with high mirror ratio of {approx}1:1.7. We have specifically used the radio frequency compensated Langmuir probe (LP) to measure the relevant plasma parameters simultaneously so as to investigate the details about the plasma production. The DL, which consists of both warm and bulk populations towards higher potential region and only dense bulk plasmas towards the lower potential region downstream the antenna, is present in the transition region. LPmore » measurements also show an abrupt fall of density along with a potential drop of about 20 V and (e {Delta}V{sub p}/k T{sub e}) Almost-Equal-To 12 within a few cm. The potential drop is equal to the difference of the electron temperatures between the two plasma regions forming the DL, which is present in the plateau region of mirror, unlike in several prior studies on the DL formation in the region of strong gradients in the magnetic field. The DL is strong, current-free, electric double-layer with estimated thickness of about 10 Debye lengths.« less

A Study of the Physical Processes of an Advection Fog Boundary Layer

NASA Astrophysics Data System (ADS)

Liu, Duan Yang; Yan, Wen Lian; Yang, Jun; Pu, Mei Juan; Niu, Sheng Jie; Li, Zi Hua

2016-01-01

A large quantity of advection fog appeared in the Yangtze River delta region between 1 and 2 December 2009. Here, we detail the fog formation and dissipation processes and the background weather conditions. The fog boundary layer and its formation and dissipation mechanisms have also been analyzed using field data recorded in a northern suburb of Nanjing. The results showed the following: (1) This advection fog was generated by interaction between advection of a north-east cold ground layer and a south-east warm upper layer. The double-inversion structure generated by this interaction between the cold and warm advections and steady south-east vapour transport was the main cause of this long-lasting fog. The double-inversion structure provided good thermal conditions for the thick fog, and the south-east vapour transport was not only conducive to maintaining the thickness of the fog but also sustained its long duration. (2) The fog-top altitude was over 600 m for most of the time, and the fog reduced visibility to less than 100 m for approximately 12 h. (3) The low-level jet near the lower inversion layer also played a role in maintaining the thick fog system by promoting heat, momentum and south-east vapour transport.

Epitaxial growth of YBa2Cu3O7 - delta films on oxidized silicon with yttria- and zirconia-based buffer layers

NASA Astrophysics Data System (ADS)

Pechen, E. V.; Schoenberger, R.; Brunner, B.; Ritzinger, S.; Renk, K. F.; Sidorov, M. V.; Oktyabrsky, S. R.

1993-09-01

A study of epitaxial growth of YBa2Cu3O7-δ films on oxidized Si with yttria- and zirconia-based buffer layers is reported. Using substrates with either SiO2 free or naturally oxidized (100) surfaces of Si it was found that a thin SiO2 layer on top of the Si favors high-quality superconducting film formation. Compared to yttria-stabilized ZrO2 (YSZ) single layers, YSZY2O3 double and YSZ/Y2O3YSZ triple layers allows the deposition of thin YBa2Cu3O7-δ films with improved properties including reduced aging effects. In epitaxial YBa2Cu3O7-δ films grown on the double buffer layers a critical temperature Tc(R=0)=89.5 K and critical current densities of 3.5×106 A/cm2 at 77 K and 1×107 A/cm2 at 66 K were reached.

Diagnostic study of multiple double layer formation in expanding RF plasma

NASA Astrophysics Data System (ADS)

Chakraborty, Shamik; Paul, Manash Kumar; Roy, Jitendra Nath; Nath, Aparna

2018-03-01

Intensely luminous double layers develop and then expand in size in a visibly glowing RF discharge produced using a plasma source consisting of a semi-transparent cylindrical mesh with a central electrode, in a linear plasma chamber. Although RF discharge is known to be independent of device geometry in the absence of magnetic field, the initiation of RF discharge using such a plasma source results in electron drift and further expansion of the plasma in the vessel. The dynamics of complex plasma structures are studied through electric probe diagnostics in the expanding RF plasma. The measurements made to study the parametric dependence of evolution of double layer structures are analyzed and presented here. The plasma parameter measurements suggest that the complex potential structures initially form with low potential difference between the layers and then gradually expand producing burst oscillations. The present study provides interesting information about the stability of plasma sheath and charge particle dynamics in it that are important to understand the underlying basic sheath physics along with applications in plasma acceleration and propulsion.

PIC Modeling of Argon Plasma Flow in MNX

NASA Astrophysics Data System (ADS)

Cohen, Samuel; Sefkow, Adam

2007-11-01

A linear helicon-heated plasma device - the Magnetic Nozzle Experiment (MNX) at the Princeton Plasma Physics Laboratory - is used for studies of the formation of strong electrostatic double layers near mechanical and magnetic apertures and the acceleration of plasma ions into supersonic directed beams. In order to characterize the role of the aperture and its involvement with ion acceleration, detailed particle-in-cell simulations are employed to study the effects of the surrounding boundary geometry on the plasma dynamics near the aperture region, within which the transition from a collisional to collisionless regime occurs. The presence of a small superthermal electron population is examined, and the model includes a background neutral population which can be ionized by energetic electrons. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the formation mechanism of the double layer is investigated.

On the secondary eyewall formation of Hurricane Edouard (2014)

PubMed Central

Abarca, Sergio F.; Montgomery, Michael T.; Braun, Scott A.; Dunion, Jason

2018-01-01

A first observationally-based estimation of departures from gradient wind balance during secondary eyewall formation is presented. The study is based on the Atlantic Hurricane Edouard (2014). This storm was observed during the National Aeronautics and Space Administration’s (NASA) Hurricane and Severe Storm Sentinel (HS3) experiment, a field campaign conducted in collaboration with the National Oceanic and Atmospheric Administration (NOAA). A total of 135 dropsondes are analyzed in two separate time periods: one named the secondary eyewall formation period and the other one referred to as the decaying-double eyewalled storm period. During the secondary eyewall formation period, a time when the storm was observed to have only one eyewall, the diagnosed agradient force has a secondary maxima that coincides with the radial location of the secondary eyewall observed in the second period of study. The maximum spin up tendency of the radial influx of absolute vertical vorticity is within the boundary layer in the region of the eyewall of the storm and the spin up tendency structure elongates radially outward into the secondary region of supergradient wind, where the secondary wind maxima is observed in the second period of study. An analysis of the boundary-layer averaged vertical structure of equivalent potential temperature reveals a conditionally unstable environment in the secondary eyewall formation region. These findings support the hypothesis that deep convective activity in this region contributed to spin up of the boundary layer tangential winds and the formation of a secondary eyewall that is observed during the decaying-double eyewalled storm period. PMID:29651170

On the Secondary Eyewall Formation of Hurricane Edouard (2014)

NASA Technical Reports Server (NTRS)

Abarca, Sergio F.; Montgomery, Michael T.; Braun, Scott A.; Dunion, Jason

2016-01-01

A first observationally-based estimation of departures from gradient wind balance during secondary eyewall formation is presented. The study is based on the Atlantic Hurricane Edouard (2014). This storm was observed during the National Aeronautics and Space Administrations (NASA) Hurricane and Severe Storm Sentinel (HS3) experiment, a field campaign conducted in collaboration with the National Oceanic and Atmospheric Administration (NOAA). A total of 135 dropsondes are analyzed in two separate time periods: one named the secondary eyewall formation period and the other one referred to as the decaying-double eyewalled storm period. During the secondary eyewall formation period, a time when the storm was observed to have only one eyewall, the diagnosed agradient force has a secondary maxima that coincides with the radial location of the secondary eyewall observed in the second period of study. The maximum spin up tendency of the radial influx of absolute vertical vorticity is within the boundary layer in the region of the eyewall of the storm and the spin up tendency structure elongates radially outward into the secondary region of supergradient wind, where the secondary wind maxima is observed in the second period of study. An analysis of the boundary layer averaged vertical structure of equivalent potential temperature reveals a conditionally unstable environment in the secondary eyewall formation region. These findings support the hypothesis that deep convective activity in this region contributed to spin up of the boundary layer tangential winds and the formation of a secondary eyewall that is observed during the decaying-double eyewalled storm period.

On the secondary eyewall formation of Hurricane Edouard (2014).

PubMed

Abarca, Sergio F; Montgomery, Michael T; Braun, Scott A; Dunion, Jason

2016-09-01

A first observationally-based estimation of departures from gradient wind balance during secondary eyewall formation is presented. The study is based on the Atlantic Hurricane Edouard (2014). This storm was observed during the National Aeronautics and Space Administration's (NASA) Hurricane and Severe Storm Sentinel (HS3) experiment, a field campaign conducted in collaboration with the National Oceanic and Atmospheric Administration (NOAA). A total of 135 dropsondes are analyzed in two separate time periods: one named the secondary eyewall formation period and the other one referred to as the decaying-double eyewalled storm period. During the secondary eyewall formation period, a time when the storm was observed to have only one eyewall, the diagnosed agradient force has a secondary maxima that coincides with the radial location of the secondary eyewall observed in the second period of study. The maximum spin up tendency of the radial influx of absolute vertical vorticity is within the boundary layer in the region of the eyewall of the storm and the spin up tendency structure elongates radially outward into the secondary region of supergradient wind, where the secondary wind maxima is observed in the second period of study. An analysis of the boundary-layer averaged vertical structure of equivalent potential temperature reveals a conditionally unstable environment in the secondary eyewall formation region. These findings support the hypothesis that deep convective activity in this region contributed to spin up of the boundary layer tangential winds and the formation of a secondary eyewall that is observed during the decaying-double eyewalled storm period.

Strongly nonlinear dynamics of electrolytes in large ac voltages.

PubMed

Højgaard Olesen, Laurits; Bazant, Martin Z; Bruus, Henrik

2010-07-01

We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional problem by matched asymptotic expansions in the limit of thin double layers and extend previous work into the strongly nonlinear regime, which is characterized by two features--significant salt depletion in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasiequilibrium structure of the double layers. The former leads to the prediction of "ac capacitive desalination" since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion layers. The latter is associated with transient diffusion limitation, which drives the formation and collapse of space-charge layers, even in the absence of any net Faradaic current through the cell. We also predict that steric effects of finite ion sizes (going beyond dilute-solution theory) act to suppress the strongly nonlinear regime in the limit of concentrated electrolytes, ionic liquids, and molten salts. Beyond the model problem, our reduced equations for thin double layers, based on uniformly valid matched asymptotic expansions, provide a useful mathematical framework to describe additional nonlinear responses to large ac voltages, such as Faradaic reactions, electro-osmotic instabilities, and induced-charge electrokinetic phenomena.

Influence of double- and triple-layer antireflection coatings on the formation of photocurrents in multijunction III–V solar cells

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

Musalinov, S. B.; Anzulevich, A. P.; Bychkov, I. V.

2017-01-15

The results of simulation by the transfer-matrix method of TiO{sub 2}/SiO{sub 2} double-layer and TiO{sub 2}/Si{sub 3}N{sub 4}/SiO{sub 2} triple-layer antireflection coatings for multijunction InGaP/GaAs/Ge heterostructure solar cells are presented. The TiO{sub 2}/SiO{sub 2} double-layer antireflection coating is experimentally developed and optimized. The experimental spectral dependences of the external quantum yield of the InGaP/GaAs/Ge heterostructure solar cell and optical characteristics of antireflection coatings, obtained in the simulation, are used to determine the photogenerated current densities of each subcell in the InGaP/GaAs/Ge solar cell under AM1.5D irradiation conditions (1000 W/m{sup 2}) and for the case of zero reflection loss. It ismore » shown in the simulation that the optimized TiO{sub 2}/Si{sub 3}N{sub 4}/SiO{sub 2} triple-layer antireflection coating provides a 2.3 mA/cm{sup 2} gain in the photocurrent density for the Ge subcell under AM1.5D conditions in comparison with the TiO{sub 2}/SiO{sub 2} double-layer antireflection coating under consideration. This thereby provides an increase in the fill factor of the current–voltage curve and in the output electric power of the multijunction solar cell.« less

Overexpression of the lamina proteins Lamin and Kugelkern induces specific ultrastructural alterations in the morphology of the nuclear envelope of intestinal stem cells and enterocytes.

PubMed

Petrovsky, Roman; Krohne, Georg; Großhans, Jörg

2018-03-01

The nuclear envelope has a stereotypic morphology consisting of a flat double layer of the inner and outer nuclear membrane, with interspersed nuclear pores. Underlying and tightly linked to the inner nuclear membrane is the nuclear lamina, a proteinous layer of intermediate filament proteins and associated proteins. Physiological, experimental or pathological alterations in the constitution of the lamina lead to changes in nuclear morphology, such as blebs and lobulations. It has so far remained unclear whether the morphological changes depend on the differentiation state and the specific lamina protein. Here we analysed the ultrastructural morphology of the nuclear envelope in intestinal stem cells and differentiated enterocytes in adult Drosophila flies, in which the proteins Lam, Kugelkern or a farnesylated variant of LamC were overexpressed. Surprisingly, we detected distinct morphological features specific for the respective protein. Lam induced envelopes with multiple layers of membrane and lamina, surrounding the whole nucleus whereas farnesylated LamC induced the formation of a thick fibrillary lamina. In contrast, Kugelkern induced single-layered and double-layered intranuclear membrane structures, which are likely be derived from infoldings of the inner nuclear membrane or of the double layer of the envelope. Copyright © 2018 Elsevier GmbH. All rights reserved.

Biodiesel synthesis using calcined layered double hydroxide catalysts

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

Schumaker, J. Link; Crofcheck, Czarena; TAckett, S. Adam

2008-01-01

The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sitesmore » active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.« less

Pseudocapacitance of MXene nanosheets for high-power sodium-ion hybrid capacitors

PubMed Central

Wang, Xianfen; Kajiyama, Satoshi; Iinuma, Hiroki; Hosono, Eiji; Oro, Shinji; Moriguchi, Isamu; Okubo, Masashi; Yamada, Atsuo

2015-01-01

High-power Na-ion batteries have tremendous potential in various large-scale applications. However, conventional charge storage through ion intercalation or double-layer formation cannot satisfy the requirements of such applications owing to the slow kinetics of ion intercalation and the small capacitance of the double layer. The present work demonstrates that the pseudocapacitance of the nanosheet compound MXene Ti2C achieves a higher specific capacity relative to double-layer capacitor electrodes and a higher rate capability relative to ion intercalation electrodes. By utilizing the pseudocapacitance as a negative electrode, the prototype Na-ion full cell consisting of an alluaudite Na2Fe2(SO4)3 positive electrode and an MXene Ti2C negative electrode operates at a relatively high voltage of 2.4 V and delivers 90 and 40 mAh g−1 at 1.0 and 5.0 A g−1 (based on the weight of the negative electrode), respectively, which are not attainable by conventional electrochemical energy storage systems. PMID:25832913

Formation of hexagonal and cubic ice during low-temperature growth

PubMed Central

Thürmer, Konrad; Nie, Shu

2013-01-01

From our daily life we are familiar with hexagonal ice, but at very low temperature ice can exist in a different structure––that of cubic ice. Seeking to unravel the enigmatic relationship between these two low-pressure phases, we examined their formation on a Pt(111) substrate at low temperatures with scanning tunneling microscopy and atomic force microscopy. After completion of the one-molecule-thick wetting layer, 3D clusters of hexagonal ice grow via layer nucleation. The coalescence of these clusters creates a rich scenario of domain-boundary and screw-dislocation formation. We discovered that during subsequent growth, domain boundaries are replaced by growth spirals around screw dislocations, and that the nature of these spirals determines whether ice adopts the cubic or the hexagonal structure. Initially, most of these spirals are single, i.e., they host a screw dislocation with a Burgers vector connecting neighboring molecular planes, and produce cubic ice. Films thicker than ∼20 nm, however, are dominated by double spirals. Their abundance is surprising because they require a Burgers vector spanning two molecular-layer spacings, distorting the crystal lattice to a larger extent. We propose that these double spirals grow at the expense of the initially more common single spirals for an energetic reason: they produce hexagonal ice. PMID:23818592

A double-layer based model of ion confinement in electron cyclotron resonance ion source.

PubMed

Mascali, D; Neri, L; Celona, L; Castro, G; Torrisi, G; Gammino, S; Sorbello, G; Ciavola, G

2014-02-01

The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this "barrier" confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

Non-mean-field theory of anomalously large double layer capacitance

NASA Astrophysics Data System (ADS)

Loth, M. S.; Skinner, Brian; Shklovskii, B. I.

2010-07-01

Mean-field theories claim that the capacitance of the double layer formed at a metal/ionic conductor interface cannot be larger than that of the Helmholtz capacitor, whose width is equal to the radius of an ion. However, in some experiments the apparent width of the double layer capacitor is substantially smaller. We propose an alternate non-mean-field theory of the ionic double layer to explain such large capacitance values. Our theory allows for the binding of discrete ions to their image charges in the metal, which results in the formation of interface dipoles. We focus primarily on the case where only small cations are mobile and other ions form an oppositely charged background. In this case, at small temperature and zero applied voltage dipoles form a correlated liquid on both contacts. We show that at small voltages the capacitance of the double layer is determined by the transfer of dipoles from one electrode to the other and is therefore limited only by the weak dipole-dipole repulsion between bound ions so that the capacitance is very large. At large voltages the depletion of bound ions from one of the capacitor electrodes triggers a collapse of the capacitance to the much smaller mean-field value, as seen in experimental data. We test our analytical predictions with a Monte Carlo simulation and find good agreement. We further argue that our “one-component plasma” model should work well for strongly asymmetric ion liquids. We believe that this work also suggests an improved theory of pseudocapacitance.

Nano- and micro-structuring of fused silica using time-delay adjustable double flash ns-laser radiation

NASA Astrophysics Data System (ADS)

Lorenz, Pierre; Zhao, Xiongtao; Ehrhardt, Martin; Zagoranskiy, Igor; Zimmer, Klaus; Han, Bing

2018-02-01

Large area, high speed, nanopatterning of surfaces by laser ablation is challenging due to the required high accuracy of the optical and mechanical systems fulfilling the precision of nanopatterning process. Utilization of self-organization approaches can provide an alternative decoupling spot precision and field of machining. The laser-induced front side etching (LIFE) and laser-induced back side dry etching (LIBDE) of fused silica were studied using single and double flash nanosecond laser pulses with a wavelength of 532 nm where the time delay Δτ of the double flash laser pulses was adjusted from 50 ns to 10 μs. The fused silica can be etched at both processes assisted by a 10 nm chromium layer where the etching depth Δz at single flash laser pulses is linear to the laser fluence and independent on the number of laser pulses, from 2 to 12 J/cm2, it is Δz = δLIFE/LIBDE . Φ with δLIFE 16 nm/(J/cm2) and δLIBDE 5.2 nm/(J/cm2) 3 . δLIFE. At double flash laser pulses, the Δz is dependent on the time delay Δτ of the laser pulses and the Δz slightly increased at decreasing Δτ. Furthermore, the surface nanostructuring of fused silica using IPSM-LIFE (LIFE using in-situ pre-structured metal layer) method with a single double flash laser pulse was tested. The first pulse of the double flash results in a melting of the metal layer. The surface tension of the liquid metal layer tends in a droplet formation process and dewetting process, respectively. If the liquid phase life time ΔtLF is smaller than the droplet formation time the metal can be "frozen" in an intermediated state like metal bare structures. The second laser treatment results in a evaporation of the metal and in a partial evaporation and melting of the fused silica surface, where the resultant structures in the fused silica surface are dependent on the lateral geometry of the pre-structured metal layer. A successful IPSM-LIFE structuring could be achieved assisted by a 20 nm molybdenum layer at Δτ >= 174 ns. That path the way for the high speed ultra-fast nanostructuring of dielectric surfaces by self-organizing processes. The different surface structures were analyzed by scanning electron microscopy (SEM) and white light interferometry (WLI).

Structural, vibrational and morphological properties of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations

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

Bezerra, Débora M.

2017-03-15

Layered double hydroxides are anionic clays with formula [M{sup II}{sub 1−x} M{sup III}{sub x}(OH){sub 2}]{sup q+}[A{sup n−}]{sub q/n}·mH{sub 2}O, finding possible uses as catalyst support, adsorbents and so on. In this paper, we address the phase formation of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations, namely, NiZn-Al, NiZn-AlZr and NiZn-Zr compositions obtained by the coprecipitation method. Such systems were characterized by X-ray diffraction, confirming the phase formation for NiZn-Al and NiZn-AlZr samples. Infrared and Raman spectroscopies elucidated the anion and water molecules occurrence in the interlayer. Nitrogen physisorption (BET method) determined the presencemore » of pores and specific surface area. The isotherm shapes were Type IV, according to the IUPAC, and represent a mesoporous structure. A morphological study was performed by means of scanning and transmission electron microscopies, and particle size values of 120, 131 and 235 nm for NiZn-Al, NiZn-AlZr and NiZn-Zr, respectively, were determined. Thermogravimetric analysis of the decomposition of the systems revealed that their complete disintegration occurred at ~ 450 °C and resulted in mixed oxides.« less

Dynamical Generation of the Transition Zone in the Earth's Mantle

NASA Astrophysics Data System (ADS)

Hansen, U.; Stemmer, K.

2005-12-01

The internal structure of the Earth is made up by a series of layers, though it is unclear how many layers exist and if there are layers invisible to remote sensing techniques. The transition zone is likely to be a boundary layer separating the convective systems in the lower and upper mantle. It seems likely that currently there is some mass exchange across this boundary, rather than the two systems beeing strictly separated.a Double-diffusive convection(d.d.c) is a vital mechanism which can generate layered structure and may thus be an important mmical machinery behind the formation of the transition zone. Double-diffusive convection determines the dynamics of systems whose density is influenced by at least two components with different molecular diffusivities.In the mantle, composition and temperature play the role of those two components. By means of numerical experiments we demonstrate that under mantle relevant conditions d.d.c typically leads to the formation of a transition zone. The calculations encompass two- and three dimensional Cartesian geometries as well as fully 3D spherical domains. We have further included strongly temperature dependent viscosity and find that this leads to even more pronounced layering. In most cases a layered flow pattern emerges, where two layers with a transition zone in between resembles a quasistationary state. Thus, the transition zone can be the result of a self organization process of the convective flow in the mantle. The presence of a phase transition further helps to stabilize the boundary against overturning, even on a time scale on the order of the age of the Earth.

Plasma response to the injection of an electron beam

NASA Technical Reports Server (NTRS)

Singh, N.; Schunk, R. W.

1984-01-01

The results of Vlasov-Poisson-solver numerical simulations of the detailed temporal response of a Maxwellian plasma to the sudden injection of an electron beam are presented in graphs and maps and discussed. Phenomena characterized include ion bursts, electron shocks and holes, plasma heating and expulsion, density gradients; cavitons, deep-density-front and solitary-pulse propagation down the density gradient, and Bunemann-mode excitation leading to formation of a virtual cathode and double layers which are at first monotonic or have low-potential-side dips or high-potential-side bumps and become strong as the electron-current density decreases. The strength of the double layer is found to be roughly proportional to the beam energy.

Similar solutions of double-diffusive dissipative layers along free surfaces

NASA Astrophysics Data System (ADS)

Napolitano, L. G.; Viviani, A.; Savino, R.

1990-10-01

Free convection due to buoyant forces (natural convection) and surface tension gradients (Marangoni convection) generated by temperature and concentration gradients is discussed together with the formation of double-diffusive boundary layers along liquid-gas interfaces. Similarity solutions for each class of free convection are derived and the resulting nonlinear two-point problems are solved numerically using the quasi-linearization method. Velocity, temperature, concentration profiles, interfacial velocity, heat and mass transfer bulk coefficients for various Prandtl and Schmidt numbers, and different values of the similarity parameters are determined. The convective flows are of particular interest because they are considered to influence the processes of crystal growth, both on earth and in a microgravity environment.

Universal biomimetic preparation and immobilization of layered double hydroxide films and adsorption behavior

NASA Astrophysics Data System (ADS)

Zhou, Wei; Zhang, Wenpeng; Chen, Zilin

2017-01-01

Preparation and immobilization of layered double hydroxides (LDHs) film onto multiple substrates is important and challenging in functional materials fields by date. In this work, a simple and universal polydopamine (PD)-based layer-by-layer assembly strategy was developed for the immobilization of LDHs film onto surfaces such as polypropylene chip, glass slides and metal coins. The surface of substrates was firstly modified by polydopamine functionalization, and then LDHs film was synthesized via urea method and directly immobilized on the PD layer by in situ growing strategy in one step. The PD layer as well as the final LDHs film was characterized by energy dispersive X-ray spectroscopy, scanning electron microscope, infrared spectroscopy, X-ray diffraction pattern and X-ray photoelectron spectra. It has been demonstrated the formation of the dense and homogeneous nanoscaled LDHs film with 400 nm thickness. Adsorption behavior of the fabricated NiAl-LDHs film toward anionic dyes and pharmaceuticals was further assessed. To demonstrate their extensive application, fast and high efficient adsorption of anionic dyes and pharmaceuticals was achieved by NiAl-LDHs-modified polypropylene centrifugal tube.

Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

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

Kim, Jinhyun; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

2012-10-15

Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughnessmore » and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.« less

Room temperature multiferroic properties of (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4} double layered thin film

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

Raghavan, C.M.; Kim, H.J.; Kim, J.W.

2013-11-15

Graphical abstract: - Highlights: • Chemical solution deposition of (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}–NiFe{sub 2}O{sub 4} double layered thin film. • Studies on structural, electrical and multiferroic properties. • NiFe{sub 2}O{sub 4} acts as both resistive buffer layer and magnetic source. - Abstract: (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4} double layered thin film was prepared on a Pt(111)/Ti/SiO{sub 2}/Si(100) substrate by a chemical solution deposition method. X-ray diffraction and Raman scattering spectroscopy studies confirmed the formation of the distorted rhombohedral perovskite and the inverse spinel cubic structures for the (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4}more » double layered thin film. The (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4} double layered thin film exhibited well saturated ferromagnetic (2 M{sub r} of 18.1 emu/cm{sup 3} and 2H{sub c} of 0.32 kOe at 20 kOe) and ferroelectric (2P{sub r} of 60 μC/cm{sup 2} and 2E{sub c} of 813 kV/cm at 866 kV/cm) hysteresis loops with low order of leakage current density (4.5 × 10{sup −6} A/cm{sup 2} at an applied electric field of 100 kV/cm), which suggest the ferroelectric and ferromagnetic multi-layers applications in real devices.« less

Ion acceleration and non-Maxwellian electron distributions in a low collisionality, high power helicon plasma source

NASA Astrophysics Data System (ADS)

Li, Yan; Sung, Yung-Ta; Scharer, John

2015-11-01

Ion acceleration through plasma double layer and non-Maxwellian two temperature electron distributions have been observed in Madison Helicon Experiment (MadHeX) operated in high RF power (>1000 W) and low Ar pressure (0.17 mtorr) inductive mode. By applying Optical Emission Spectroscopy (OES) cross-checked with an RF-compensated Langmuir probe (at 13.56 MHz and its second and third harmonics), the fast (>80 eV), untrapped electrons downstream of the double layer have a higher temperature of 13 eV than the trapped bulk electrons upstream with a temperature of 4 eV. The reduction of plasma potential and density observed in the double layer region require an upstream temperature ten times the measured 4 eV if occurring via Boltzmann ambipolar expansion. The hot tail electrons of the non-Maxwellian electron distribution affect the formation and the potential drop of the double layer region. The mechanism behind this has been explored via several non-invasive plasma diagnostics tools. The OES measured electron temperatures and densities are also cross-checked with Atomic Data and Analysis Structure (ADAS) and a millimeter wave interferometer respectively. The IEDF is measured by a four-grid RPA and also cross-checked with argon 668 nm Laser Induced Fluorescence (LIF). An emissive probe has been used to measure the plasma potential.

Highly efficient organic light-emitting diodes with a quantum dot interfacial layer.

PubMed

Ryu, Seung Yoon; Hwang, Byoung Har; Park, Ki Wan; Hwang, Hyeon Seok; Sung, Jin Woo; Baik, Hong Koo; Lee, Chang Ho; Song, Seung Yong; Lee, Jun Yeob

2009-02-11

Advanced organic light-emitting diodes (OLEDs), based on a multiple structure, were achieved in combination with a quantum dot (QD) interfacial layer. The authors used core/shell CdSe/ZnS QDs passivated with trioctylphosphine oxide (TOPO) and TOPO-free QDs as interlayers. Multiple-structure OLEDs (MOLEDs) with TOPO-free QDs showed higher device efficiency because of a well-defined interfacial monolayer formation. Additionally, the three-unit MOLED showed high performance for device efficiency with double-structured QD interfacial layers due to the enhanced charge balance and recombination probability.

The double layers in the plasma sheet boundary layer during magnetic reconnection

NASA Astrophysics Data System (ADS)

Guo, J.; Yu, B.

2014-11-01

We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

Obtention of low oxidation states of copper from Cu 2+-Al 3+ layered double hydroxides containing organic sulfonates in the interlayer

NASA Astrophysics Data System (ADS)

Trujillano, Raquel; Holgado, María Jesús; Rives, Vicente

2009-03-01

A series of hydrotalcite-type compounds containing Cu(II) and Al(III) in the layers, and carbonate or different alkylsulfonates in the interlayer, have been prepared and studied. Calcination of these solids gives rise to formation of metallic copper and Cu 2+ and Cu + oxides or sulfates, depending on the calcination temperature and on the precise nature of the interlayer alkylsulfonate.

Partial double-layered patella in a nondysplasic adolescent.

PubMed

García-Mata, Serafín; Hidalgo-Ovejero, Angel

2016-11-01

Double-layered patella (DLP) is a rare patella-formation abnormality reported in association with multiple epiphyseal dysplasia. DLP is one of the five types of bipartite patella, caused by a coronal septum that divides the patella into anterior and posterior segments. Although the double layer of bone has been reported as complete, it may also manifest as partial, as in our case. A 13-year-old male patient attended A&E after accidentally falling and sustaining a direct injury to his left knee, with pain in the anterior surface of the right patella. He was diagnosed with an incomplete vertical fracture of the left patella. An axial view radiography indicated an external partial DLP. No bone dysplasia was found. Computed tomographic scan and MRI showed partial DLP and bone marrow oedema because of the injury in the femoral condyle, but no fracture. The reason for highlighting this type of patella abnormality is to present the case of a patient without bone dysplasia, either partial or incomplete, that has not been reported previously. We also wish to emphasize the importance of not confusing it with a fracture in standard radiographies.

Theoretical Study of α-V2O5 -Based Double-Wall Nanotubes.

PubMed

Porsev, Vitaly V; Bandura, Andrei V; Evarestov, Robert A

2015-10-05

First-principles calculations of the atomic and electronic structure of double-wall nanotubes (DWNTs) of α-V2 O5 are performed. Relaxation of the DWNT structure leads to the formation of two types of local regions: 1) bulk-type regions and 2) puckering regions. Calculated total density of states (DOS) of DWNTs considerably differ from that of single-wall nanotubes and the single layer, as well as from the DOS of the bulk and double layer. Small shoulders that appear on edges of valence and conduction bands result in a considerable decrease in the band gaps of the DWNTs (up to 1 eV relative to the single-layer gaps). The main reason for this effect is the shift of the inner- and outer-wall DOS in opposite directions on the energetic scale. The electron density corresponding to shoulders at the conduction-band edges is localized on vanadium atoms of the bulk-type regions, whereas the electron density corresponding to shoulders at the valence-band edges belongs to oxygen atoms of both regions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bose-Einstein condensation and superfluidity of dipolar excitons in a phosphorene double layer

NASA Astrophysics Data System (ADS)

Berman, Oleg L.; Gumbs, Godfrey; Kezerashvili, Roman Ya.

2017-07-01

We study the formation of dipolar excitons and their superfluidity in a phosphorene double layer. The analytical expressions for the single dipolar exciton energy spectrum and wave function are obtained. It is predicted that a weakly interacting gas of dipolar excitons in a double layer of black phosphorus exhibits superfluidity due to the dipole-dipole repulsion between the dipolar excitons. In calculations are employed the Keldysh and Coulomb potentials for the interaction between the charge carriers to analyze the influence of the screening effects on the studied phenomena. It is shown that the critical velocity of superfluidity, the spectrum of collective excitations, concentrations of the superfluid and normal component, and mean-field critical temperature for superfluidity are anisotropic and demonstrate the dependence on the direction of motion of dipolar excitons. The critical temperature for superfluidity increases if the exciton concentration and the interlayer separation increase. It is shown that the dipolar exciton binding energy and mean-field critical temperature for superfluidity are sensitive to the electron and hole effective masses. The proposed experiment to observe a directional superfluidity of excitons is addressed.

An experimental investigation of alternative propellants for the helicon double layer thruster

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Laine, R.; MacLellan, P.

2008-09-01

Ion energy distribution functions are measured using a retarding field energy analyser located 7.5 cm downstream of a helicon double layer plasma source, respectively, operating with four molecular gases: nitrogen (N2), methane (CH4), ammonia (NH3) and nitrous oxide (N2O). For radiofrequency powers of a few hundred watts, and a magnetic field diverging from about 0.013 T (130 G) in the source to about 0.001 T (10 G) in the exhaust, an ion beam is detected for each propellant over a very similar operating pressure range (~0.023 Pa (0.17 mTorr) to ~0.267 Pa (2 mTorr)), as a result of spontaneous electric double layer formation near the exit of the plasma source. The characteristics of the ion beam versus operating pressure closely follow those previously obtained in argon, xenon and hydrogen. The ion beam exhaust velocity in space is found to be in the 17-19 km s-1 range in N2, 21-27 km s-1 range in CH4 and NH3 and 14-16 km s-1 range in N2O.

Polyethylenimine/kappa carrageenan: Micro-arc oxidation coating for passivation of magnesium alloy.

PubMed

Golshirazi, A; Kharaziha, M; Golozar, M A

2017-07-01

The aim of this study was to combine micro-arc oxidation (MAO) and self-assembly technique to improve corrosion resistivity of AZ91 alloy. While a silicate-fluoride electrolyte was adopted for MAO treatment, polyethylenimine (PEI)/kappa carrageenan (KC) self-assembly coating was applied as the second coating layer. Resulted demonstrated the formation of forsterite-fluoride containing MAO coating on AZ91 alloy depending on the voltage and time of anodizing process. Addition of the second PEI/KC coating layer on MAO treated sample effectively enhanced the adhesive strength of MAO coated sample due to filling the pores with polymers and increase in the mechanical interlocking of coating to the substrate. Moreover, the corrosion evaluation considered by potentiodynamic polarization and electrochemical impedance spectroscopy confirmed that double layered PEI/KC:MAO coating presented superior resistance to corrosion attack. It is envisioned that the proposed double layered PEI/KC:MAO coating could be useful for biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparative study of heterostructured CuO/CuWO4 nanowires and thin films

NASA Astrophysics Data System (ADS)

Polyakov, Boris; Kuzmin, Alexei; Vlassov, Sergei; Butanovs, Edgars; Zideluns, Janis; Butikova, Jelena; Kalendarev, Robert; Zubkins, Martins

2017-12-01

A comparative study of heterostructured CuO/CuWO4 core/shell nanowires and double-layer thin films was performed through X-ray diffraction, confocal micro-Raman spectroscopy and electron (SEM and TEM) microscopies. The heterostructures were produced using a two-step process, starting from a deposition of amorphous WO3 layer on top of CuO nanowires and thin films by reactive DC magnetron sputtering and followed by annealing at 650 °C in air. The second step induced a solid-state reaction between CuO and WO3 oxides through a thermal diffusion process, revealed by SEM-EDX analysis. Morphology evolution of core/shell nanowires and double-layer thin films upon heating was studied by electron (SEM and TEM) microscopies. A formation of CuWO4 phase was confirmed by X-ray diffraction and confocal micro-Raman spectroscopy.

Chemical-mechanical planarization of aluminum and copper interconnects with magnetic liners

NASA Astrophysics Data System (ADS)

Wang, Bin

2000-10-01

Chemical Mechanical Planarization (CMP) has been employed to achieve Damascene patterning of aluminum and copper interconnects with unique magnetic liners. A one-step process was developed for each interconnect scheme, using a double-layered pad with mesh cells, pores, and perforations on a top hard layer. In a hydrogen peroxide-based slurry, aluminum CMP was a process of periodic removal and formation of a surface oxide layer. Cu CMP in the same slurry, however, was found to be a dissolution dominant process. In a potassium iodate-based slurry, copper removal was the result of two competing reactions: copper dissolution and a non-native surface layer formation. Guided by electrochemistry, slurries were developed to remove nickel in different regimes of the corrosion kinetics diagram. Nickel CMP in a ferric sulfate-based slurry resulted in periodic removal and formation of a passive surface layer. In a potassium permanganate-based slurry, nickel removal is a dissolution dominant process. Visible Al(Cu) surface damages obtained with copper-doped aluminum could be eliminated by understanding the interactions between the substrate, the pad, and the abrasive agglomerate. Increasing substrate hardness by annealing prior to CMP led to a surface finish free of visible scratches. A similar result was also obtained by preventing formation of abrasive agglomerates and minimizing their contact with the substrate.

TiS2 and ZrS2 single- and double-wall nanotubes: first-principles study.

PubMed

Bandura, Andrei V; Evarestov, Robert A

2014-02-15

Hybrid density functional theory has been applied for investigations of the electronic and atomic structure of bulk phases, nanolayers, and nanotubes based on titanium and zirconium disulfides. Calculations have been performed on the basis of the localized atomic functions by means of the CRYSTAL-2009 computer code. The full optimization of all atomic positions in the regarded systems has been made to study the atomic relaxation and to determine the most favorable structures. The different layered and isotropic bulk phases have been considered as the possible precursors of the nanotubes. Calculations on single-walled TiS2 and ZrS2 nanotubes confirmed that the nanotubes obtained by rolling up the hexagonal crystalline layers with octahedral 1T morphology are the most stable. The strain energy of TiS2 and ZrS2 nanotubes is small, does not depend on the tube chirality, and approximately obeys to D(-2) law (D is nanotube diameter) of the classical elasticity theory. It is greater than the strain energy of the similar TiO2 and ZrO2 nanotubes; however, the formation energy of the disulfide nanotubes is considerably less than the formation energy of the dioxide nanotubes. The distance and interaction energy between the single-wall components of the double-wall nanotubes is proved to be close to the distance and interaction energy between layers in the layered crystals. Analysis of the relaxed nanotube shape using radial coordinate of the metal atoms demonstrates a small but noticeable deviation from completely cylindrical cross-section of the external walls in the armchair-like double-wall nanotubes. Copyright © 2013 Wiley Periodicals, Inc.

An advanced Ni-Fe layered double hydroxide electrocatalyst for water oxidation.

PubMed

Gong, Ming; Li, Yanguang; Wang, Hailiang; Liang, Yongye; Wu, Justin Z; Zhou, Jigang; Wang, Jian; Regier, Tom; Wei, Fei; Dai, Hongjie

2013-06-12

Highly active, durable, and cost-effective electrocatalysts for water oxidation to evolve oxygen gas hold a key to a range of renewable energy solutions, including water-splitting and rechargeable metal-air batteries. Here, we report the synthesis of ultrathin nickel-iron layered double hydroxide (NiFe-LDH) nanoplates on mildly oxidized multiwalled carbon nanotubes (CNTs). Incorporation of Fe into the nickel hydroxide induced the formation of NiFe-LDH. The crystalline NiFe-LDH phase in nanoplate form is found to be highly active for oxygen evolution reaction in alkaline solutions. For NiFe-LDH grown on a network of CNTs, the resulting NiFe-LDH/CNT complex exhibits higher electrocatalytic activity and stability for oxygen evolution than commercial precious metal Ir catalysts.

Low temperature double-layer capacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J. (Inventor); West, William C. (Inventor); Smart, Marshall C. (Inventor)

2011-01-01

Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -75.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. An optimized concentration (e.g., 0.10 M to 0.75 M) of salt, such as tetraethylammonium tetrafluoroborate, is dissolved into the electrolyte solution. In some cases (e.g., 1,3-dioxolane cosolvent) additives, such as 2% by volume triethylamine, may be included in the solvent mixture to prevent polymerization of the solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed.

Low Temperature Double-Layer Capacitors Using Asymmetric and Spiro-Type Quaternary Ammonium Salts

NASA Technical Reports Server (NTRS)

Smart, Marshall C. (Inventor); Brandon, Erik J. (Inventor); West, William C. (Inventor)

2014-01-01

Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -80.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. A quaternary ammonium salt including at least one of triethylmethylammonium tetrafluoroborate (TEMATFB) and spiro-(1,1')-bipyrrolidium tetrafluoroborate (SBPBF.sub.4), is used in an optimized concentration (e.g., 0.10 M to 0.75 M), dissolved into the electrolyte solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed.

Enhanced electrical properties of oxide semiconductor thin-film transistors with high conductivity thin layer insertion for the channel region

NASA Astrophysics Data System (ADS)

Nguyen, Cam Phu Thi; Raja, Jayapal; Kim, Sunbo; Jang, Kyungsoo; Le, Anh Huy Tuan; Lee, Youn-Jung; Yi, Junsin

2017-02-01

This study examined the performance and the stability of indium tin zinc oxide (ITZO) thin film transistors (TFTs) by inserting an ultra-thin indium tin oxide (ITO) layer at the active/insulator interface. The electrical properties of the double channel device (ITO thickness of 5 nm) were improved in comparison with the single channel ITZO or ITO devices. The TFT characteristics of the device with an ITO thickness of less than 5 nm were degraded due to the formation of an island-like morphology and the carriers scattering at the active/insulator interface. The 5 nm-thick ITO inserted ITZO TFTs (optimal condition) exhibited a superior field effect mobility (∼95 cm2/V·s) compared with the ITZO-only TFTs (∼34 cm2/V·s). The best characteristics of the TFT devices with double channel layer are due to the lowest surface roughness (0.14 nm) and contact angle (50.1°) that result in the highest hydrophicility, and the most effective adhesion at the surface. Furthermore, the threshold voltage shifts for the ITO/ITZO double layer device decreased to 0.80 and -2.39 V compared with 6.10 and -6.79 V (for the ITZO only device) under positive and negative bias stress, respectively. The falling rates of EA were 0.38 eV/V and 0.54 eV/V for the ITZO and ITO/ITZO bi-layer devices, respectively. The faster falling rate of the double channel devices suggests that the trap density, including interface trap and semiconductor bulk trap, can be decreased by the ion insertion of a very thin ITO film into the ITZO/SiO2 reference device. These results demonstrate that the double active layer TFT can potentially be applied to the flat panel display.

Indium droplet formation in InGaN thin films with single and double heterojunctions prepared by MOCVD

PubMed Central

2014-01-01

Indium gallium nitride (InGaN) samples with single heterojunction (SH) and double heterojunction (DH) were prepared using metal-organic chemical vapor deposition. SH has a layer of InGaN thin film (thicknesses, 25, 50, 100, and 200 nm) grown on an uGaN film (thickness, 2 μm). The DH samples are distinguished by DH uGaN film (thickness, 120 nm) grown on the InGaN layer. Reciprocal space mapping measurements reveal that the DH samples are fully strained with different thicknesses, whereas the strain in the SH samples are significantly relaxed with the increasing thickness of the InGaN film. Scanning electron microscopy results show that the surface roughness of the sample increases when the sample is relaxed. High-resolution transmission electron microscopy images of the structure of indium droplets in the DH sample indicate that the thickness of the InGaN layer decreases with the density of indium droplets. The formation of these droplets is attributed to the insufficient kinetic energy of indium atom to react with the elements of group V, resulting to aggregation. The gallium atoms in the GaN thin film will not be uniformly replaced by indium atoms; the InGaN thin film has an uneven distribution of indium atoms and the quality of the epitaxial layer is degraded. PMID:25024692

Mineral induced formation of pentose-2,4-bisphosphates

NASA Technical Reports Server (NTRS)

Krishnamurthy, R.; Pitsch, S.; Arrhenius, G.; Bada, J. L. (Principal Investigator)

1999-01-01

Formation of rac.-pentose-2,4-bisphosphates is demonstrated, starting from glycolaldehyde phosphate and glyceraldehyde-2-phosphate, and induced by mixed valence double layer metal hydroxide minerals. The reactions proceed from dilute aqueous reactant solutions (1.5 mM) at near neutral pH. Conditions have been established, where ribose-2,4-bisphosphate is the major product (approximately 48%) among the pentose-2,4-bisphosphates, which are formed with up to 25% yield.

Bubble baths: just splashing around?

NASA Astrophysics Data System (ADS)

Robinson, Wesley; Speirs, Nathan; Sharker, Saberul Islam; Hurd, Randy; Williams, Bj; Truscott, Tadd

2016-11-01

Soap Bubbles on the water surface would seem to be an intuitive means for splash suppression, but their presence appears to be a double edged sword. We present on the water entry of hydrophilic spheres where the liquid surface is augmented by the presence of a bubble layer, similar to a bubble bath. While the presence of a bubble layer can diminish splashing upon impact at low Weber numbers, it also induces cavity formation at speeds below the critical velocity. The formation of a cavity generally results in larger Worthington jets and thus, larger amounts of ejected liquid. Bubble layers induce cavity formation by wetting the sphere prior to liquid impact, causing them to form cavities similar to those created by hydrophobic spheres. Droplets present on a pre-wetted sphere disrupt the flow of the advancing liquid during entry, pushing it away from the impacting body to form an entrained air cavity. This phenomena was noted by Worthington with pre-wetted stone marbles, and suggests that the application of a bubble layer is generally ineffective as a means of splash suppression.

A NEW MODEL FOR MIXING BY DOUBLE-DIFFUSIVE CONVECTION (SEMI-CONVECTION). III. THERMAL AND COMPOSITIONAL TRANSPORT THROUGH NON-LAYERED ODDC

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

Moll, Ryan; Garaud, Pascale; Stellmach, Stephan, E-mail: rmoll@soe.ucsc.edu

2016-05-20

Oscillatory double-diffusive convection (ODDC; also known as semi-convection) refers to a type of double-diffusive instability that occurs in regions of planetary and stellar interiors that have a destabilizing thermal stratification and a stabilizing mean molecular weight stratification. In this series of papers, we use an extensive suite of three-dimensional (3D) numerical simulations to quantify the transport of heat and chemical species by ODDC. Rosenblum et al. first showed that ODDC can either spontaneously form layers that significantly enhance the transport of heat and chemical species compared to microscopic transport or remain in a state dominated by large-scale gravity waves, inmore » which there is a more modest enhancement of the turbulent transport rates. Subsequent studies in this series focused on identifying under what conditions layers form and quantifying transport through layered systems. Here we proceed to characterize transport through systems that are unstable to ODDC, but do not undergo spontaneous layer formation. We measure the thermal and compositional fluxes in non-layered ODDC from both two-dimensional (2D) and 3D numerical simulations, and show that 3D simulations are well approximated by similar simulations in a 2D domain. We find that the turbulent mixing rate in this regime is weak and can, to a first-level approximation, be neglected. We conclude by summarizing the findings of papers I through III into a single prescription for transport systems unstable to ODDC.« less

Rain Reevaporation, Boundary Layer Convection Interactions, and Pacific Rainfall Patterns in an AGCM

NASA Technical Reports Server (NTRS)

Bacmeister, Julio T.; Suarez, Max J.; Robertson, Franklin R.

2004-01-01

Sensitivity experiments with an atmospheric general circulation model (AGCM) show that parameterized rain re-evaporation has a large impact on simulated precipitation patterns in the tropical Pacific, especially on the configuration of the model s intertropical convergence zone (ITCZ). Weak re-evaporation leads t o the formation of a "double ITCZ" during the northern warm season. The double ITCZ is accompanied by strong coupling between precipitation and high-frequency vertical motion in the planetary boundary layer (PBL). Strong reevaporation leads to a better overall agreement of simulated precipitation with observations. The model s double ITCZ bias is reduced. At the same time, correlation between high-frequency vertical motion in the PBL and precipitation is reduced. Experiments with modified physics suggest that evaporative cooling by rain near the PBL top weakens the coupling between precipitation and vertical motion. This may reduce the model s tendency to form double ITCZs. The strength of high-frequency vertical motions in the PBL was also reduced directly through the introduction of a diffusive cumulus momentum transport (DCMT) parameterization. The DCMT had a visible impact on simulated precipitation in the tropics, but did not reduce the model s double bias in all cases.

High performance planar p-i-n perovskite solar cells with crown-ether functionalized fullerene and LiF as double cathode buffer layers

NASA Astrophysics Data System (ADS)

Liu, Xiaodong; Lei, Ming; Zhou, Yi; Song, Bo; Li, Yongfang

2015-08-01

Double cathode buffer layers (CBLs) composed of fullerene derivative functionalized with a crown-ether end group in its side chain (denoted as PCBC) and a LiF layer were introduced between the PCBM acceptor layer and the top cathode in planar p-i-n perovskite solar cells (pero-SCs) based on CH3NH3PbI3-XClX. The devices with the PCBC/LiF double CBLs showed significant improvements in power conversion efficiency (PCE) and long-term stability when compared to the device with LiF single CBL. Through optimizing the spin-coating speed of PCBC, a maximum PCE of 15.53% has been achieved, which is approximately 15% higher than that of the device with single LiF CBL. The remarkable improvement in PCE can be attributed to the formation of a better ohmic contact in the CBL between PCBC and LiF/Al electrode arising from the dipole moment of PCBC, leading to the enhanced fill factor and short-circuit current density (Jsc). Besides the PCE, the long-term stability of the devices with PCBC interlayer is also superior to that of the device with LiF single CBL, which is due to the more effective protection for the perovskite/PCBM interface.

Research on liquid impact forming technology of double-layered tubes

NASA Astrophysics Data System (ADS)

Sun, Changying; Liu, Jianwei; Yao, Xinqi; Huang, Beixing; Li, Yuhan

2018-03-01

A double-layered tube is widely used and developed in various fields because of its perfect comprehensive performance and design. With the advent of the era of a double-layered tube, the requirements for double layered tube forming quality, manufacturing cost and forming efficiency are getting higher, so forming methods of a double-layered tube are emerged in an endless stream, the forming methods of a double-layered tube have a great potential in the future. The liquid impact forming technology is a combination of stamping technology and hydroforming technology. Forming a double-layered tube has huge advantages in production cost, quality and efficiency.

Langmuir probe measurements of double-layers in a pulsed discharge

NASA Technical Reports Server (NTRS)

Levine, J. S.; Crawford, F. W.

1980-01-01

Langmuir probe measurements were carried out which confirm the occurrence of double-layers in an argon positive column. Pulsing the discharge current permitted probe measurements to be performed in the presence of the double-layer. Supplementary evidence, obtained from DC and pulsed discharges, indicated that the double-layers formed in the two modes of operation were similar. The double-layers observed were weak and stable; their relation to other classes of double-layers are discussed, and directions for future work are suggested.

The formation of thermohaline staircases for large salt concentration differences in double diffusive convection

NASA Astrophysics Data System (ADS)

Yang, Yantao; Verzicco, Roberto; Lohse, Detlef

2016-11-01

In the upper layers of the tropical and subtropical ocean, step-like mean profiles for both temperature and salinity are often observed, a phenomenon referred to as thermohaline staircase. It consists of alternatively stacked mixing layers, and finger layers with sharp gradients in both mean temperature and salinity. It is believed that thermohaline staircases are caused by double diffusive convection (DDC), i.e. the convection flow with fluid density affected by two different scalars. Here we conducted direct numerical simulations of DDC bounded by two parallel plates and aimed to realise the multi-layer state similar to the oceanic thermohaline staircase. We applied an unstable salinity difference and a stable temperature difference across the two plates. We gradually increased the salinity Rayleigh number RaS , i.e. the strength of salinity difference, and fixed the relative strength of temperature difference. When RaS is high enough the flow undergoes a transition from a single finger layer to a triple layer state, where one mixing layer emerges between two finger layers. Such triple layer state is stable up to the turbulent diffusive time scale. The finger-layer height is larger for higher RaS . The dependences of the scalar fluxes on RaS were also investigated. Supported by Dutch FOM Foundation and NWO rpogramme MCEC; Computing resources from SURFSara and PRACE project 2015133124.

Embryological evidence for a possible polyphyletic origin of the recent amphibians.

PubMed

Nieuwkoop, P D; Sutasurya, L A

1976-02-01

The markedly different mode of mesoderm formation in anuran and urodelan amphibians (which is related to the early double-layered nature of the anuran blastula wall in contrast to its single-layered nature in the urodeles), but particularly the fundamentally different place and mode of origin of the primordial germ cells in the two groups of amphibians, strongly pleads in favour of a very ancient bifurcation in the phylogenetic history of the two groups, even suggesting a polyphyletic origin from different ancestral fishes.

Double layers and circuits in astrophysics

NASA Technical Reports Server (NTRS)

Alfven, Hannes

1986-01-01

As the rate of energy release in a double layer with voltage delta V is P approx I delta V, a double layer must be treated as a part of a circuit which delivers the current I. As neither double layer nor circuit can be derived from magnetofluid models of a plasma, such models are useless for treating energy transfer by means of double layers. They must be replaced by particle models and circuit theory. A simple circuit is suggested which is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the Sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object (one example is the double radio sources). It is tentatively suggested in X-ray and Gamma-ray bursts may be due to exploding double layers (although annihilation is an alternative energy source). A study of how a number of the most used textbooks in astrophysics treat important concepts like double layers, critical velocity, pinch effects and circuits is made.

Influence of Shell Thickness on the Colloidal Stability of Magnetic Core-Shell Particle Suspensions

PubMed Central

Neville, Frances; Moreno-Atanasio, Roberto

2018-01-01

We present a Discrete Element study of the behavior of magnetic core-shell particles in which the properties of the core and the shell are explicitly defined. Particle cores were considered to be made of pure iron and thus possessed ferromagnetic properties, while particle shells were considered to be made of silica. Core sizes ranged between 0.5 and 4.0 μm with the actual particle size of the core-shell particles in the range between 0.6 and 21 μm. The magnetic cores were considered to have a magnetization of one tenth of the saturation magnetization of iron. This study aimed to understand how the thickness of the shell hinders the formation of particle chains. Chain formation was studied with different shell thicknesses and particle sizes in the presence and absence of an electrical double layer force in order to investigate the effect of surface charge density on the magnetic core-shell particle interactions. For core sizes of 0.5 and 4.0 μm the relative shell thicknesses needed to hinder the aggregation process were approximately 0.4 and 0.6 respectively, indicating that larger core sizes are detrimental to be used in applications in which no flocculation is needed. In addition, the presence of an electrical double layer, for values of surface charge density of less than 20 mC/m2, could stop the contact between particles without hindering their vertical alignment. Only when the shell thickness was considerably larger, was the electrical double layer able to contribute to the full disruption of the magnetic flocculation process. PMID:29922646

Influence of Shell Thickness on the Colloidal Stability of Magnetic Core-Shell Particle Suspensions.

PubMed

Neville, Frances; Moreno-Atanasio, Roberto

2018-01-01

We present a Discrete Element study of the behavior of magnetic core-shell particles in which the properties of the core and the shell are explicitly defined. Particle cores were considered to be made of pure iron and thus possessed ferromagnetic properties, while particle shells were considered to be made of silica. Core sizes ranged between 0.5 and 4.0 μm with the actual particle size of the core-shell particles in the range between 0.6 and 21 μm. The magnetic cores were considered to have a magnetization of one tenth of the saturation magnetization of iron. This study aimed to understand how the thickness of the shell hinders the formation of particle chains. Chain formation was studied with different shell thicknesses and particle sizes in the presence and absence of an electrical double layer force in order to investigate the effect of surface charge density on the magnetic core-shell particle interactions. For core sizes of 0.5 and 4.0 μm the relative shell thicknesses needed to hinder the aggregation process were approximately 0.4 and 0.6 respectively, indicating that larger core sizes are detrimental to be used in applications in which no flocculation is needed. In addition, the presence of an electrical double layer, for values of surface charge density of less than 20 mC/m 2 , could stop the contact between particles without hindering their vertical alignment. Only when the shell thickness was considerably larger, was the electrical double layer able to contribute to the full disruption of the magnetic flocculation process.

Low-voltage electric-double-layer paper transistors gated by microporous SiO2 processed at room temperature

NASA Astrophysics Data System (ADS)

Sun, Jia; Wan, Qing; Lu, Aixia; Jiang, Jie

2009-11-01

Battery drivable low-voltage SnO2-based paper thin-film transistors with a near-zero threshold voltage (Vth=0.06 V) gated by microporous SiO2 dielectric with electric-double-layer (EDL) effect are fabricated at room temperature. The operating voltage is found to be as low as 1.5 V due to the huge gate specific capacitance (1.34 μF/cm2 at 40 Hz) related to EDL formation. The subthreshold gate voltage swing and current on/off ratio is found to be 82 mV/decade and 2.0×105, respectively. The electron field-effect mobility is estimated to be 47.3 cm2/V s based on the measured gate specific capacitance at 40 Hz.

Opinion formation on multiplex scale-free networks

NASA Astrophysics Data System (ADS)

Nguyen, Vu Xuan; Xiao, Gaoxi; Xu, Xin-Jian; Li, Guoqi; Wang, Zhen

2018-01-01

Most individuals, if not all, live in various social networks. The formation of opinion systems is an outcome of social interactions and information propagation occurring in such networks. We study the opinion formation with a new rule of pairwise interactions in the novel version of the well-known Deffuant model on multiplex networks composed of two layers, each of which is a scale-free network. It is found that in a duplex network composed of two identical layers, the presence of the multiplexity helps either diminish or enhance opinion diversity depending on the relative magnitudes of tolerance ranges characterizing the degree of openness/tolerance on both layers: there is a steady separation between different regions of tolerance range values on two network layers where multiplexity plays two different roles, respectively. Additionally, the two critical tolerance ranges follow a one-sum rule; that is, each of the layers reaches a complete consensus only if the sum of the tolerance ranges on the two layers is greater than a constant approximately equaling 1, the double of the critical bound on a corresponding isolated network. A further investigation of the coupling between constituent layers quantified by a link overlap parameter reveals that as the layers are loosely coupled, the two opinion systems co-evolve independently, but when the inter-layer coupling is sufficiently strong, a monotonic behavior is observed: an increase in the tolerance range of a layer causes a decline in the opinion diversity on the other layer regardless of the magnitudes of tolerance ranges associated with the layers in question.

Structural disorder of natural BimSen superlattices grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Springholz, G.; Wimmer, S.; Groiss, H.; Albu, M.; Hofer, F.; Caha, O.; Kriegner, D.; Stangl, J.; Bauer, G.; Holý, V.

2018-05-01

The structure and morphology of BimSen epitaxial layers with compositions ranging from Bi2Se3 to the Bi1Se1 grown by molecular beam epitaxy with different flux compositions are investigated by transmission electron microscopy, high-resolution x-ray diffraction, and atomic force microscopy. It is shown that the lattice structure changes significantly as a function of the beam flux composition, i.e., Se/BiSe flux ratio that determines the stoichiometry of the layers. A perfect Bi2Se3 phase is formed only with a sufficiently high additional Se flux, whereas Bi1Se1 is obtained when only a BiSe compound source without additional Se is used. For intermediate values of the excess Se flux during growth, Bi2Se3 -δ layers are obtained with the Se deficit δ varying between 0 and 1. This Se deficit is accommodated by incorporation of additional Bi-Bi double layers into the Bi2Se3 structure that otherwise exclusively consists of Se-Bi-Se-Bi-Se quintuple layers. While a periodic insertion of such Bi double layers would result in the formation of natural BimSen superlattices, we find that this Bi double-layer insertion is rather stochastic with a high degree of disorder depending on the film composition. Therefore, the structure of such epilayers is better described by a one-dimensional paracrystal model, consisting of disordered sequences of quintuple and double layers rather than by strictly periodic natural superlattices. From detailed analysis of the x-ray diffraction data, we determine the dependence of the lattice parameters a and c and distances of the individual (0001) planes dj as a function of composition, evidencing that only the in-plane lattice parameter a shows a linear dependence on composition. The simulation of the diffraction curves with the random stacking paracrystal model yields an excellent agreement with the experimental data and it brings quantitative information on the randomness of the stacking sequence, which is compared to growth modeling using Monte Carlo simulations. The analysis of transmission electron microscopy data furthermore confirms that the Bi-Bi bilayers contain a large amount of vacancies of up to 25%. Conductivity and Hall data confirm that BimSen phases containing Bi-Bi double layers exhibit a rather semimetallic behavior.

Design of latex-layered double hydroxide composites by tuning the aggregation in suspensions.

PubMed

Pavlovic, Marko; Rouster, Paul; Bourgeat-Lami, Elodie; Prevot, Vanessa; Szilagyi, Istvan

2017-01-25

Colloidal stability of polymeric latex particles was studied in the presence of oppositely charged layered double hydroxide (LDH) platelets of different interlayer anions. Adsorption of the LDH particles led to charge neutralization and to overcharging of the latex at appropriate concentrations. Mixing stable colloidal suspensions of individual particles results in rapid aggregation once the LDH adsorption neutralizes the negative charges of the polymer spheres, while stable suspensions were observed at high and low LDH doses. The governing interparticle interactions included repulsive electrical double layer forces as well as van der Waals and patch-charge attractions, whose strength depended on the amount of LDH particles adsorbed on the latex surface. The type of the LDH interlayer anions did not affect the colloidal stability of the samples. Structural investigation of the obtained latex-LDH composites revealed that the polymer spheres were completely coated with the inorganic platelets once their concentration was sufficiently high. These results are especially important for designing synthetic routes for hybrid systems in suspensions, where stable colloids are required for uniform film-formation and for the homogeneous distribution of the inorganic filler within the composite materials.

Simulation of plasma double-layer structures

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1982-01-01

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2 dimensional particle in cell method. The investigation of planar double layers indicates that these one dimensional potential structures are susceptible to periodic disruption by instabilities in the low potential plasmas. Only a slight increase in the double layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double layer electric field alignment of accelerated particles and strong magnetization results in their magnetic field alignment. The numerical simulations of spatially periodic two dimensional double layers also exhibit cyclical instability. A morphological invariance in two dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron beam excited electrostatic electron cyclotron waves and (ion beam driven) solitary waves are present in the plasmas adjacent to the double layers.

Bioinspired metal-cell wall-metal sandwich structure on an individual bacterial cell scaffold.

PubMed

Zhang, Xiaoliang; Yu, Mei; Liu, Jianhua; Li, Songmei

2012-08-25

Pd nanoparticles were introduced to individual Bacillus cells and dispersedly anchored on both the inside and outside of the cell walls. The anchored nanoparticles served as "seeds" to drive the formation of double metallic layers forming a metal-cell wall-metal sandwich structure at the single-cell level.

Concentration of simple aldehydes by sulfite-containing double-layer hydroxide minerals: implications for biopoesis

NASA Technical Reports Server (NTRS)

Pitsch, S.; Krishnamurthy, R.; Arrhenius, G.; Bada, J. L. (Principal Investigator)

2000-01-01

Environmental conditions play an important role in conceptual studies of prebiotically relevant chemical reactions that could have led to functional biomolecules. The necessary source compounds are likely to have been present in dilute solution, raising the question of how to achieve selective concentration and to reach activation. With the assumption of an initial 'RNA World', the questions of production, concentration, and interaction of aldehydes and aldehyde phosphates, potential precursors of sugar phosphates, come into the foreground. As a possible concentration process for simple, uncharged aldehydes, we investigated their adduct formation with sulfite ion bound in the interlayer of positively charged expanding-sheet-structure double-layer hydroxide minerals. Minerals of this type, initially with chloride as interlayer counter anion, have previously been shown to induce concentration and subsequent aldolization of aldehyde phosphates to form tetrose, pentose, and hexose phosphates. The reversible uptake of the simple aldehydes formaldehyde, glycolaldehyde, and glyceraldehyde by adduct formation with the immobilized sulfite ions is characterized by equilibrium constants of K=1.5, 9, and 11, respectively. This translates into an observable uptake at concentrations exceeding 50 mM.

Prospects for reducing the processing cost of lithium ion batteries

DOE PAGES

Wood III, David L.; Li, Jianlin; Daniel, Claus

2014-11-06

A detailed processing cost breakdown is given for lithium-ion battery (LIB) electrodes, which focuses on: elimination of toxic, costly N-methylpyrrolidone (NMP) dispersion chemistry; doubling the thicknesses of the anode and cathode to raise energy density; and, reduction of the anode electrolyte wetting and SEI-layer formation time. These processing cost reduction technologies generically adaptable to any anode or cathode cell chemistry and are being implemented at ORNL. This paper shows step by step how these cost savings can be realized in existing or new LIB manufacturing plants using a baseline case of thin (power) electrodes produced with NMP processing and amore » standard 10-14-day wetting and formation process. In particular, it is shown that aqueous electrode processing can cut the electrode processing cost and energy consumption by an order of magnitude. Doubling the thickness of the electrodes allows for using half of the inactive current collectors and separators, contributing even further to the processing cost savings. Finally wetting and SEI-layer formation cost savings are discussed in the context of a protocol with significantly reduced time. These three benefits collectively offer the possibility of reducing LIB pack cost from $502.8 kWh-1-usable to $370.3 kWh-1-usable, a savings of $132.5/kWh (or 26.4%).« less

Parallel electric fields in extragalactic jets - Double layers and anomalous resistivity in symbiotic relationships

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1986-01-01

After examining the properties of Coulomb-collision resistivity, anomalous (collective) resistivity, and double layers, a hybrid anomalous-resistivity/double-layer model is introduced. In this model, beam-driven waves on both sides of a double layer provide electrostatic plasma-wave turbulence that greatly reduces the mobility of charged particles. These regions then act to hold open a density cavity within which the double layer resides. In the double layer, electrical energy is dissipated with 100 percent efficiency into high-energy particles, creating conditions optimal for the collective emission of polarized radio waves.

Self-propagated combustion synthesis of few-layered graphene: an optical properties perspective.

PubMed

Mohandoss, Manonmani; Sen Gupta, Soujit; Kumar, Ramesh; Islam, Md Rabiul; Som, Anirban; Mohd, Azhardin Ganayee; Pradeep, T; Maliyekkal, Shihabudheen M

2018-04-26

This paper describes a labour efficient and cost-effective strategy to prepare few-layered of reduced graphene oxide like (RGOL) sheets from graphite. The self-propagated combustion route enables the bulk production of RGOL sheets. Microscopic and spectroscopic analyses confirmed the formation of few-layer graphene sheets of an average thickness of ∼3 nm and the presence of some oxygen functional groups with a C/O ratio of 8.74. A possible mechanistic pathway for the formation of RGOL sheets is proposed. The optical properties of the RGOL sample were studied in detail by means of Spectroscopic Ellipsometry (SE). The experimental abilities of SE in relating the optical properties with the number of oxygen functionalities present in the samples are explored. The data were analysed by a double-layered optical model along with the Drude-Lorentz oscillatory dispersion relation. The refractive index (n = 2.24), extinction coefficient (k = 2.03), and dielectric functions are obtained using point-by-point analysis and are also checked for Kramers-Kronig (KK) consistency.

Ionic liquids behave as dilute electrolyte solutions

PubMed Central

Gebbie, Matthew A.; Valtiner, Markus; Banquy, Xavier; Fox, Eric T.; Henderson, Wesley A.; Israelachvili, Jacob N.

2013-01-01

We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force–distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical control and quantitatively modeled these measurements using the van der Waals and electrostatic double-layer forces of the Derjaguin–Landau–Verwey–Overbeek theory with an additive repulsive steric (entropic) ion–surface binding force. Our results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions. Additionally, we used the energetics of thermally dissociating ions in a dielectric medium to quantitatively predict the equilibrium for the effective dissociation reaction of [C4mim][NTf2] ions, in excellent agreement with the measured Debye length. Our results clearly demonstrate that, outside of the bound double layer, most of the ions in [C4mim][NTf2] are not effectively dissociated and thus do not contribute to electrostatic screening. We also provide a general, molecular-scale framework for designing ionic liquids with significantly increased dissociated charge densities via judiciously balancing ion pair interactions with bulk dielectric properties. Our results clear up several inconsistencies that have hampered scientific progress in this important area and guide the rational design of unique, high–free-ion density ionic liquids and ionic liquid blends. PMID:23716690

How to improve outcome in surgery for Proximal Hypospadias?

PubMed

Qureshi, Abdul Hafeez; Zaidi, Syed Zafar

2016-02-01

To evaluate the role of subdartos fascial tissue as watertight layer in improving outcome for 2-stage proximal hypospadias surgery. The experimental study was conducted at the Department of Urology, Indus Hospital, Karachi, and comprised an audit of patients with proximal hypospadias who underwent surgery from July 1, 2007, to December 31, 2011. The initial two-stage repair of proximal hypospadias led to a high rate of urethrocutanous fistula formation (Group A), and, thus, a modification was introduced and subdartos facial double layer was applied over the urethral suture line (Group B). The results were compared regarding age, type of hypospadias, graft failure and urethrocutanous fistula in these patients. There were 27 patients in Group A and 16(59.3%) of them ended up having urethrocutanous fistula. Group B had 25 patients and only 2(8%) had fistula formation. The application of dartos facial flap waterproofing layer reduced fistula rate.

High performance planar p-i-n perovskite solar cells with crown-ether functionalized fullerene and LiF as double cathode buffer layers

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

Liu, Xiaodong; Zhou, Yi, E-mail: yizhou@suda.edu.cn, E-mail: songbo@suda.edu.cn, E-mail: liyf@iccas.ac.cn; Song, Bo, E-mail: yizhou@suda.edu.cn, E-mail: songbo@suda.edu.cn, E-mail: liyf@iccas.ac.cn

2015-08-10

Double cathode buffer layers (CBLs) composed of fullerene derivative functionalized with a crown-ether end group in its side chain (denoted as PCBC) and a LiF layer were introduced between the PCBM acceptor layer and the top cathode in planar p-i-n perovskite solar cells (pero-SCs) based on CH{sub 3}NH{sub 3}PbI{sub 3−X}Cl{sub X}. The devices with the PCBC/LiF double CBLs showed significant improvements in power conversion efficiency (PCE) and long-term stability when compared to the device with LiF single CBL. Through optimizing the spin-coating speed of PCBC, a maximum PCE of 15.53% has been achieved, which is approximately 15% higher than thatmore » of the device with single LiF CBL. The remarkable improvement in PCE can be attributed to the formation of a better ohmic contact in the CBL between PCBC and LiF/Al electrode arising from the dipole moment of PCBC, leading to the enhanced fill factor and short-circuit current density (J{sub sc}). Besides the PCE, the long-term stability of the devices with PCBC interlayer is also superior to that of the device with LiF single CBL, which is due to the more effective protection for the perovskite/PCBM interface.« less

Structure of oxides prepared by decomposition of layered double Mg–Al and Ni–Al hydroxides

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

Cherepanova, Svetlana V.; Novosibirsk State University, Novosibirsk; Leont’eva, Natalya N., E-mail: n_n_leonteva@list.ru

2015-05-15

Abstracts: Thermal decomposition of Mg–Al and Ni–Al layered double hydroxides LDH at temperatures lower than 800 °C leads to the formation of oxides with different structures. Mg–Al oxide has a very defective structure and consists of octahedral layers as in periclase MgO and mixed octahedral–tetrahedral layers as in spinel MgAl{sub 2}O{sub 4}. Mixed Ni–Al oxide has a sandwich-like structure, consisting of a core with Al-doped NiO-like structure and some surface layers with spinel NiAl{sub 2}O{sub 4} structure epitaxial connected with the core. Suggested models were verified by simulation of X-ray diffraction patterns using DIFFaX code, as well as HRTEM, IR-,more » UV-spectroscopies, and XPS. - Graphical abstract: In the Mg–Al layered double hydroxide Al{sup 3+} ions migrate into interlayers during decomposition. The Mg–Al oxide represents sequence of octahedral and octahedral–tetrahedral spinel layers with vacancies. The Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers as a result of migration of Al{sup 3+} ions on the surface. The models explain the presence and absence of “memory effect” for the Mg–Al and Ni–Al oxides, respectively. - Highlights: • We study products of Mg(Ni)–Al LDH decomposition by calcination at 500(400)–800 °C. • In Mg–Al/Ni–Al LDH Al ions migrate into interlayers/on the surface during decomposition. • Mg–Al oxide represents sequence of periclase- and spinel-like layers with vacancies. • Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers. • The models explain the presence/absence of “memory effect” for Mg–Al/Ni–Al oxides.« less

Adsorption and Formation of Small Na Clusters on Pristine and Double-Vacancy Graphene for Anodes of Na-Ion Batteries.

PubMed

Liang, Zhicong; Fan, Xiaofeng; Zheng, Weitao; Singh, David J

2017-05-24

Layered carbon is a likely anode material for Na-ion batteries (NIBs). Graphitic carbon has a low capacity of approximately 35 (mA h)/g due to the formation of NaC 64 . Using first-principles methods including van der Waals interactions, we analyze the adsorption of Na ions and clusters on graphene in the context of anodes. The interaction between Na ions and graphene is found to be weak. Small Na clusters are not stable on the surface of pristine graphene in the electrochemical environment of NIBs. However, we find that Na ions and clusters can be stored effectively on defected graphene that has double vacancies. In addition, the adsorption energy of small Na clusters near a double vacancy is found to decrease with increasing cluster size. With high concentrations of vacancies the capacity of Na on defective graphene is found to be as much as 10-30 times higher than that of graphitic carbon.

Double Emulsion Generation Using a Polydimethylsiloxane (PDMS) Co-axial Flow Focus Device.

PubMed

Cole, Russell H; Tran, Tuan M; Abate, Adam R

2015-12-25

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper presents a polydimethylsiloxane (PDMS) microfluidic device capable of generating water/oil/water double emulsions using a coaxial flow focusing geometry that can be fabricated entirely using soft lithography. Similar to emulsion devices using glass capillaries, double emulsions can be formed in channels with uniform wettability and with dimensions much smaller than the channel sizes. Three dimensional flow focusing geometry is achieved by casting a pair of PDMS slabs using two layer soft lithography, then mating the slabs together in a clamshell configuration. Complementary locking features molded into the PDMS slabs enable the accurate registration of features on each of the slab surfaces. Device testing demonstrates formation of double emulsions from 14 µm to 50 µm in diameter while using large channels that are robust against fouling and clogging.

Double Emulsion Generation Using a Polydimethylsiloxane (PDMS) Co-axial Flow Focus Device

PubMed Central

Cole, Russell H.; Tran, Tuan M.; Abate, Adam R.

2015-01-01

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper presents a polydimethylsiloxane (PDMS) microfluidic device capable of generating water/oil/water double emulsions using a coaxial flow focusing geometry that can be fabricated entirely using soft lithography. Similar to emulsion devices using glass capillaries, double emulsions can be formed in channels with uniform wettability and with dimensions much smaller than the channel sizes. Three dimensional flow focusing geometry is achieved by casting a pair of PDMS slabs using two layer soft lithography, then mating the slabs together in a clamshell configuration. Complementary locking features molded into the PDMS slabs enable the accurate registration of features on each of the slab surfaces. Device testing demonstrates formation of double emulsions from 14 µm to 50 µm in diameter while using large channels that are robust against fouling and clogging. PMID:26780079

Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

PubMed

Lassnig, R; Hollerer, M; Striedinger, B; Fian, A; Stadlober, B; Winkler, A

2015-11-01

In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p ++ -silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification

PubMed Central

Lassnig, R.; Hollerer, M.; Striedinger, B.; Fian, A.; Stadlober, B.; Winkler, A.

2015-01-01

In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p++-silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3–4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact–channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility. PMID:26543442

New layered double hydroxides by prepared by the intercalation of gibbsite

NASA Astrophysics Data System (ADS)

Rees, Jennifer R.; Burden, Chloe S.; Fogg, Andrew M.

2015-04-01

New layered double hydroxides (LDHs) with the composition [MAl4(OH)12]Cl2·1.5H2O (M=Co, Ni) have been prepared by reacting gibbsite, γ-Al(OH)3, with the appropriate chloride salt in a synthesis in which the water of crystallization is the only solvent present and fully characterized. These LDHs have been shown to undergo facile anion exchange reactions with both organic and inorganic anions at room temperature making them comparable to other LDHs in this respect. Reactions under the same conditions with CuCl2·2H2O and ZnCl2 failed to form the desired LDHs but those with nitrate salts did lead to the formation of the previously reported [MAl4(OH)12](NO3)2·1.5H2O (M=Co, Ni) compounds.

In-situ confined formation of NiFe layered double hydroxide quantum dots in expanded graphite for active electrocatalytic oxygen evolution

NASA Astrophysics Data System (ADS)

Guo, Jinxue; Li, Xiaoyan; Sun, Yanfang; Liu, Qingyun; Quan, Zhenlan; Zhang, Xiao

2018-06-01

Development of noble-metal-free catalysts towards highly efficient electrochemical oxygen evolution reaction (OER) is critical but challenging in the renewable energy area. Herein, we firstly embed NiFe LDHs quantum dots (QDs) into expanded graphite (NiFe LDHs/EG) via in-situ confined formation process. The interlayer spacing of EG layers acts as nanoreactors for spatially confined formation of NiFe LDHs QDs. The QDs supply huge catalytic sites for OER. The in-situ decoration endows the strong affinity between QDs with EG, thus inducing fast charge transfer. Based on the aforementioned benefits, the designed catalyst exhibits outstanding OER properties, in terms of small overpotential (220 mV required to generate 10 mA cm-2), low Tafel slope, and good durable stability, making it a promising candidate for inexpensive OER catalyst.

The scaling of oblique plasma double layers

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1983-01-01

Strong oblique plasma double layers are investigated using three methods, i.e., electrostatic particle-in-cell simulations, numerical solutions to the Poisson-Vlasov equations, and analytical approximations to the Poisson-Vlasov equations. The solutions to the Poisson-Vlasov equations and numerical simulations show that strong oblique double layers scale in terms of Debye lengths. For very large potential jumps, theory and numerical solutions indicate that all effects of the magnetic field vanish and the oblique double layers follow the same scaling relation as the field-aligned double layers.

Breast-implant texturing associated with delamination of capsular layers: A histological analysis of the double capsule phenomenon.

PubMed

Efanov, J I; Giot, J P; Fernandez, J; Danino, M A

2017-06-01

Macro-texturing of breast implants was developed with the double goal of improving implant stabilization within the breast cavity and decreasing the rate of capsular contractures. However, recent evidence suggests that double capsular formation, a potentially worrisome phenomenon associated with late seromas and biofilms, occurs with preponderance in macro-textured implants. Our objective was to analyze histologically different regions of double capsules to determine if they are more prone to mechanical movements. A prospective analysis including patients undergoing second-stage expander to definitive breast-implant reconstruction post-mastectomy was conducted after intraoperative identification of the double capsule phenomenon. Two samples were collected from each capsules around the implant, located centrally and laterally. The specimens were sent for histological analysis by the institution's pathologist. In total, 10 patients were identified intraoperatively with partial double capsule phenomenon. Among samples retrieved from the lateral aspect of the breast implant, all were associated with delamination and fractures in the collagen matrix of the double capsules. This phenomenon was not observed in any sample from the dome of the breast. Breast-implant macro-texturing plays an important role on delamination of capsules on lateral portions of the breast, which may have an etiologic role in double capsule formation. Manufacturing implants with macro-texturing on one side and smooth surface on the other could diminish mechanical shear forces responsible for these findings. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Photon induced non-linear quantized double layer charging in quaternary semiconducting quantum dots.

PubMed

Nair, Vishnu; Ananthoju, Balakrishna; Mohapatra, Jeotikanta; Aslam, M

2018-03-15

Room temperature quantized double layer charging was observed in 2 nm Cu 2 ZnSnS 4 (CZTS) quantum dots. In addition to this we observed a distinct non-linearity in the quantized double layer charging arising from UV light modulation of double layer. UV light irradiation resulted in a 26% increase in the integral capacitance at the semiconductor-dielectric (CZTS-oleylamine) interface of the quantum dot without any change in its core size suggesting that the cause be photocapacitive. The increasing charge separation at the semiconductor-dielectric interface due to highly stable and mobile photogenerated carriers cause larger electrostatic forces between the quantum dot and electrolyte leading to an enhanced double layer. This idea was supported by a decrease in the differential capacitance possible due to an enhanced double layer. Furthermore the UV illumination enhanced double layer gives us an AC excitation dependent differential double layer capacitance which confirms that the charging process is non-linear. This ultimately illustrates the utility of a colloidal quantum dot-electrolyte interface as a non-linear photocapacitor. Copyright © 2017 Elsevier Inc. All rights reserved.

A Study of the Physical Processes of an Advection Fog BoundaryLayer

NASA Astrophysics Data System (ADS)

Liu, D.; Yan, W.; Kang, Z.; Dai, Z.; Liu, D.; Liu, M.; Cao, L.; Chen, H.

2016-12-01

Using the fog boundary layer observation collected by a moored balloon between December 1 and 2, 2009, the processes of advection fog formation and dissipation under cold and warm double-advection conditions was studied. the conclusions are as follows: 1. The advection fog process was generated by the interaction between the near-surface northeast cold advection and the upper layer's southeast warm, humid advection. The ground fog formed in an advection cooling process, and the thick fog disappeared in two hours when the wind shifted from the northeast to the northwest. The top of the fog layer remained over 600 m for most of the time. 2. This advection fog featured a double-inversion structure. The interaction between the southeast warm, humid advection of the upper layer and the descending current generated the upper inversion layer. The northeast cold advection near the ground and the warm, humid advection in the high-altitude layer formed the lower layer clouds and lower inversion layer. The upper inversion layer was composed of southeast warm, humid advection and a descending current with increasing temperature. The double inversion provided good thermal conditions for maintaining the thick fog layer. 3. The southeast wind of the upper layer not only created the upper inversion layer but also brought vapour-rich air to the fog region. The steady southeast vapour transportation by the southeast wind was the main condition that maintained the fog thickness, homogeneous density, and long duration. The low-altitude low-level jet beneath the lower inversion layer helped maintain the thickness and uniform density of the fog layer by enhancing the exchange of heat, momentum and vapour within the lower inversion layer. 4. There were three transportation mechanisms associated with this advection fog: 1) The surface layer vapour was delivered to the lower fog layer. 2) The low-altitude southeast low-level jet transported the vapour to the upper layer. 3) The vapour was exchanged between the upper and lower layers via the turbulent exchange and vertical air motion, which mixed the fog density and maintained the thickness of the fog. These mechanisms explain why the fog top was higher than the lower inversion layer and reached the upper inversion layer, as well as why this advection fog was so thick.

Electrophoretic formation of semiconductor layers with adjustable band gap

NASA Astrophysics Data System (ADS)

Shindrov, Alexander; Yuvchenko, Sergey; Vikulova, Maria; Tretyachenko, Elena; Zimnyakov, Dmitry; Gorokhovsky, Alexander

2017-11-01

The ceramic layers of the potassium polytitanates modified by transition metal salts were electrophoretically deposited onto the surface of glassy substrate coated with indium-tin oxide. The deposition allows obtaining a dense ceramic layer formed by composite agglomerates consisting of nanoscale particles with average size of 130-190 nm. The optical absorption spectra of the coatings modified in the mixtures of aqueous solutions of different transition metal salts were investigated. It was recognized that a bandgap value of these composites can be adjusted in a range from 1.4 to 2.3 eV depending the chemical composition of layered double hydroxide obtained during modification. This might be very promising for optoelectronic applications of such coatings due to an explicit control of optical properties.

Tests on Double Layer Metalization

NASA Technical Reports Server (NTRS)

Woo, D. S.

1983-01-01

28 page report describes experiments in fabrication of integrated circuits with double-layer metalization. Double-layer metalization requires much less silicon "real estate" and allows more flexibility in placement of circuit elements than does single-layer metalization.

Disappearing Enantiomorphs: Single Handedness in Racemate Crystals.

PubMed

Parschau, Manfred; Ernst, Karl-Heinz

2015-11-23

Although crystallization is the most important method for the separation of enantiomers of chiral molecules in the chemical industry, the chiral recognition involved in this process is poorly understood at the molecular level. We report on the initial steps in the formation of layered racemate crystals from a racemic mixture, as observed by STM at submolecular resolution. Grown on a copper single-crystal surface, the chiral hydrocarbon heptahelicene formed chiral racemic lattice structures within the first layer. In the second layer, enantiomerically pure domains were observed, underneath which the first layer contained exclusively the other enantiomer. Hence, the system changed from a 2D racemate into a 3D racemate with enantiomerically pure layers after exceeding monolayer-saturation coverage. A chiral bias in form of a small enantiomeric excess suppressed the crystallization of one double-layer enantiomorph so that the pure minor enantiomer crystallized only in the second layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions

NASA Astrophysics Data System (ADS)

Jiang, Xikai; Huang, Jingsong; Zhao, Hui; Sumpter, Bobby G.; Qiao, Rui

2014-07-01

We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential from molecular dynamics (MD) simulations during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (Bazant et al 2011 Phys. Rev. Lett. 106 046102). Under very large charging currents, the cell potential from MD simulations shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface. This allows the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant-current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. The evolution of ion density profiles is also compared between the MD and the continuum model, showing good agreement.

Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions.

PubMed

Jiang, Xikai; Huang, Jingsong; Zhao, Hui; Sumpter, Bobby G; Qiao, Rui

2014-07-16

We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential from molecular dynamics (MD) simulations during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (Bazant et al 2011 Phys. Rev. Lett. 106 046102). Under very large charging currents, the cell potential from MD simulations shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface. This allows the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant-current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. The evolution of ion density profiles is also compared between the MD and the continuum model, showing good agreement.

Double-layer versus single-layer bone-patellar tendon-bone anterior cruciate ligament reconstruction: a prospective randomized study with 3-year follow-up.

PubMed

Mei, Xiaoliang; Zhang, Zhenxiang; Yang, Jingwen

2016-12-01

To evaluate the clinical results of a randomized controlled trial of single-layer versus double-layer bone-patellar tendon-bone (BPTB) anterior cruciate ligament (ACL) reconstruction. Fifty-eight subjects who underwent primary ACL reconstruction with a BPTB allograft were prospectively randomized into two groups: single-layer reconstruction (n = 31) and double-layer reconstruction (n = 27). The following evaluation methods were used: clinical examination, KT-1000 arthrometer measurement, muscle strength, Tegner activity score, Lysholm score, subjective rating scale regarding patient satisfaction and sports performance level, graft retear, contralateral ACL tear, and additional meniscus surgery. Forty-eight subjects (24 in single-layer group and 24 in double-layer group) who were followed up for 3 years were evaluated. Preoperatively, there were no differences between the groups. At 3-year follow-up, the Lachman and pivot-shift test results were better in the double-layer group (P = 0.019 and P < 0.0001, respectively). KT measurements were better in the double-layer group (mean 2.9 versus 1.5 mm; P = 0.0025). The Tegner score was also better in the double-layer group (P = 0.024). There were no significant differences in range of motion, muscle strength, Lysholm score, subjective rating scale, graft retear, and secondary meniscal tear. In ACL reconstruction, double-layer BPTB reconstruction was significantly better than single-layer reconstruction regarding anterior and rotational stability at 3-year follow-up. The results of KT measurements and the Lachman and pivot-shift tests were significantly better in the double-layer group, whereas there was no difference in the anterior drawer test results. The Tegner score was also better in the double-layer group; however, there were no differences in the other subjective findings.

ZIF-67-derived hollow nanocages with layered double oxides shell as high-Efficiency catalysts for CO oxidation

NASA Astrophysics Data System (ADS)

Kong, Wenpeng; Li, Jing; Chen, Yao; Ren, Yuqing; Guo, Yonghua; Niu, Shengli; Yang, Yanzhao

2018-04-01

Constructing non-precious hybrid metal oxides with specific morphology as cost-effective and highly efficient catalysts is a promising way for the automotive exhaust purification. In this work, we report a facile strategy for the fabrication of a unique hollow Co-Ni layered double oxides (HLDO) nanocages by using zeolitic imidazole frameworks (ZIFs) as template. The synthesis of intermediate core-shell and hollow Co-Ni layered double hydroxides (HLDH) nanoflakes as well as the corresponding Co-Ni oxides products were successfully controlled, and the formation process was also explained. Among ZIF-67-derived oxides, HLDO exhibits excellent catalytic activities (complete conversion of CO into CO2 at 118 °C) and long-term stability for CO oxidation. The remarkable catalytic activities of HLDO can be attributed to high surface area (258 m2 g-1) inherited from the HLDH, which could provide more active sites for CO oxidation. In addition, active oxygen species indicated by the O 1 s XPS spectrum and improved synergistic effect between NiO and Co3O4 reflected by H2-TPR, further explain the enhanced performance of the HLDO catalysts. The presented strategy for controlled design and synthesis of hollow multicomponent metal oxides will provide prospects in developing highly effective catalysts.

Electrochemistry with double electrical layers in frictional interaction metal-polymer tribolink

NASA Astrophysics Data System (ADS)

Volchenko, N. A.; Krasin, P. S.; Volchenko, D. A.; Voznyi, A. V.

2018-03-01

The materials of the article illustrate the estimation of the energy loading of a metal friction element in a “metal-electrolyte-polymer” friction pair while forming various types of double electrical layers with the release of its thermal stabilization state. The rapidity of the processes of oxidation and reduction of the working surfaces of friction pairs during their electrothermomechanical frictional interaction leaves an imprint on all other additional processes that subsequently lead to the thermostabilizing and steady state of the metal friction element. Depending on the type of a brake device, the metal friction element has a different metal consumption and the temperature range varies. In addition, it is shown that the materials of the friction pair play an important role in the formation of electric tribosystems, namely: chemical elements that make up the materials, their valence, and the predominant type of intrinsic conductivity, as well as the sign of the electric charge of the friction pair elements that determines the laws of triboelectricity. Thus, an in-depth approach to the evaluation of the thermal stabilization state of a metal element in a “metal-electrolyte” friction pair is shown due to double electric layers that promote the emergence of current densities of different directions.

Observation of a stationary, current-free double layer in a plasma

NASA Technical Reports Server (NTRS)

Hairapetian, G.; Stenzel, R. L.

1990-01-01

A stationary, current-free, potential double layer is formed in a two-electron-population plasma due to self-consistent separation of the two electron species. The position and amplitude of the double layer are controlled by the relative densities of the two electron populations. The steady-state double layer traps the colder electrons on the high potential side, and generates a neutralized, monoenergetic ion beam on the low potential side. The field-aligned double layer is annihilated when an electron current is drawn through the plasma.

Substituted Quaternary Ammonium Salts Improve Low-Temperature Performance of Double-Layer Capacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J.; Smart, Marshall C.; West, William C.

2011-01-01

Double-layer capacitors are unique energy storage devices, capable of supporting large current pulses as well as a very high number of charging and discharging cycles. The performance of doublelayer capacitors is highly dependent on the nature of the electrolyte system used. Many applications, including for electric and fuel cell vehicles, back-up diesel generators, wind generator pitch control back-up power systems, environmental and structural distributed sensors, and spacecraft avionics, can potentially benefit from the use of double-layer capacitors with lower equivalent series resistances (ESRs) over wider temperature limits. Higher ESRs result in decreased power output, which is a particular problem at lower temperatures. Commercially available cells are typically rated for operation down to only 40 C. Previous briefs [for example, Low Temperature Supercapacitors (NPO-44386), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), p. 32, and Supercapacitor Electrolyte Solvents With Liquid Range Below 80 C (NPO-44855), NASA Tech Briefs, Vol. 34, No. 1 (January 2010), p. 44] discussed the use of electrolytes that employed low-melting-point co-solvents to depress the freezing point of traditional acetonitrile-based electrolytes. Using these modified electrolyte formulations can extend the low-temperature operational limit of double-layer capacitors beyond that of commercially available cells. This previous work has shown that although the measured capacitance is relatively insensitive to temperature, the ESR can rise rapidly at low temperatures, due to decreased electrolyte conductance within the pores of the high surface- area carbon electrodes. Most of these advanced electrolyte systems featured tetraethylammonium tetrafluoroborate (TEATFB) as the salt. More recent work at JPL indicates the use of the asymmetric quaternary ammonium salt triethylmethylammonium tetrafluoroborate (TEMATFB) or spiro-(l,l')-bipyrrolidium tetrafluoroborate (SBPBF4) in a 1:1 by volume solvent mixture of acetonitrile (AN) and methyl formate (MF) enables double-layer capacitor cells to operate well below -40 C with a relatively low ESR. Typically, a less than twofold increase in ESR is observed at -65 C relative to room-temperature values, when these modified electrolyte blends are used in prototype cells. Double-layer capacitor coin cells filled with these electrolytes have displayed the lowest measured ESR for an organic electrolyte to date at low temperature (based on a wide range of electrolyte screening studies at JPL). The cells featured high-surface-area (approximately equal to 2,500 m/g) carbon electrodes that were 0.50 mm thick and 1.6 cm in diameter, and coated with a thin layer of platinum to reduce cell resistance. A polyethylene separator was used to electrically isolate the electrodes.

Transition from single to multiple double layers. [of plasma

NASA Technical Reports Server (NTRS)

Chan, C.; Hershkowitz, N.

1982-01-01

Laboratory results are presented to define parameters which allow the boundary conditions to control the characteristics of double layers of plasma. It is shown that multiple double layers arise when the ratio of Debye length to system length decreases, a result which is in line with boundary layer theory. The significance of inclusion of the system length is noted to render BGK treatments of double layers, wherein the length is neglected, invalid.

Nanoplasmonic sensing of metal-halide complex formation and the electric double layer capacitor.

PubMed

Dahlin, Andreas B; Zahn, Raphael; Vörös, Janos

2012-04-07

Many nanotechnological devices are based on implementing electrochemistry with plasmonic nanostructures, but these systems are challenging to understand. We present a detailed study of the influence of electrochemical potentials on plasmon resonances, in the absence of surface coatings and redox active molecules, by synchronized voltammetry and spectroscopy. The experiments are performed on gold nanodisks and nanohole arrays in thin gold films, which are fabricated by improved methods. New insights are provided by high resolution spectroscopy and variable scan rates. Furthermore, we introduce new analytical models in order to understand the spectral changes quantitatively. In contrast to most previous literature, we find that the plasmonic signal is caused almost entirely by the formation of ionic complexes on the metal surface, most likely gold chloride in this study. The refractometric sensing effect from the ions in the electric double layer can be fully neglected, and the charging of the metal gives a surprisingly small effect for these systems. Our conclusions are consistent for both localized nanoparticle plasmons and propagating surface plasmons. We consider the results in this work especially important in the context of combined electrochemical and optical sensors. This journal is © The Royal Society of Chemistry 2012

Effects of hydroxyapatite/Zr and bioglass/Zr coatings on morphology and corrosion behaviour of Rex-734 alloy.

PubMed

Say, Y; Aksakal, B

2016-06-01

To improve corrosion resistance of metallic implant surfaces, Rex-734 alloy was coated with two different bio-ceramics; single-Hydroxyapatite (HA), double-HA/Zirconia(Zr) and double-Bioglass (BG)/Zr by using sol-gel method. Porous surface morphologies at low crack density were obtained after coating and sintering processes. Corrosion characteristics of coatings were determined by Open circuit potential and Potentiodynamic polarization measurements during corrosion tests. Hardness and adhesion strength of coating layers were measured and their surface morphologies before and after corrosion were characterized by scanning electron microscope (SEM), XRD and EDX. Through the SEM analysis, it was observed that corrosion caused degradation and sphere-like formations appeared with dimples on the coated surfaces. The coated substrates that exhibit high crack density, the corrosion was more effective by disturbing and transmitting through the coating layer, produced CrO3 and Cr3O8 oxide formation. It was found that the addition of Zr provided an increase in adhesion strength and corrosion resistance of the coatings. However, BG/Zr coatings had lower adhesion strength than the HA/Zr coatings, but showed higher corrosion resistance.

Influence of the charge double layer on solid oxide fuel cell stack behavior

NASA Astrophysics Data System (ADS)

Whiston, Michael M.; Bilec, Melissa M.; Schaefer, Laura A.

2015-10-01

While the charge double layer effect has traditionally been characterized as a millisecond phenomenon, longer timescales may be possible under certain operating conditions. This study simulates the dynamic response of a previously developed solid oxide fuel cell (SOFC) stack model that incorporates the charge double layer via an equivalent circuit. The model is simulated under step load changes. Baseline conditions are first defined, followed by consideration of minor and major deviations from the baseline case. This study also investigates the behavior of the SOFC stack with a relatively large double layer capacitance value, as well as operation of the SOFC stack under proportional-integral (PI) control. Results indicate that the presence of the charge double layer influences the SOFC stack's settling time significantly under the following conditions: (i) activation and concentration polarizations are significantly increased, or (ii) a large value of the double layer capacitance is assumed. Under normal (baseline) operation, on the other hand, the charge double layer effect diminishes within milliseconds, as expected. It seems reasonable, then, to neglect the charge double layer under normal operation. However, careful consideration should be given to potential variations in operation or material properties that may give rise to longer electrochemical settling times.

Modeling electrical double-layer effects for microfluidic impedance spectroscopy from 100 kHz to 110 GHz.

PubMed

Little, Charles A E; Orloff, Nathan D; Hanemann, Isaac E; Long, Christian J; Bright, Victor M; Booth, James C

2017-07-25

Broadband microfluidic-based impedance spectroscopy can be used to characterize complex fluids, with applications in medical diagnostics and in chemical and pharmacological manufacturing. Many relevant fluids are ionic; during impedance measurements ions migrate to the electrodes, forming an electrical double-layer. Effects from the electrical double-layer dominate over, and reduce sensitivity to, the intrinsic impedance of the fluid below a characteristic frequency. Here we use calibrated measurements of saline solution in microfluidic coplanar waveguide devices at frequencies between 100 kHz and 110 GHz to directly measure the double-layer admittance for solutions of varying ionic conductivity. We successfully model the double-layer admittance using a combination of a Cole-Cole response with a constant phase element contribution. Our analysis yields a double-layer relaxation time that decreases linearly with solution conductivity, and allows for double-layer effects to be separated from the intrinsic fluid response and quantified for a wide range of conducting fluids.

Transport Properties of Anatase-TiO2 Polycrystalline-Thin-Film Field-Effect Transistors with Electrolyte Gate Layers

NASA Astrophysics Data System (ADS)

Horita, Ryohei; Ohtani, Kyosuke; Kai, Takahiro; Murao, Yusuke; Nishida, Hiroya; Toya, Taku; Seo, Kentaro; Sakai, Mio; Okuda, Tetsuji

2013-11-01

We have fabricated anatase-TiO2 polycrystalline-thin-film field-effect transistors (FETs) with poly(vinyl alcohol) (PVA), ion-liquid (IL), and ion-gel (IG) gate layers, and have tried to improve the response to gate voltage by varying the concentration of mobile ions in these electrolyte gate layers. The increase in the concentration of mobile ions by doping NaOH into the PVA gate layer or reducing the gelator in the IG gate layer markedly increases the drain-source current and reduces the driving gate voltage, which show that the mobile ions in the PVA, IL, and IG gate layers cause the formation of electric double layers (EDLs), which act as nanogap capacitors. In these TiO2-EDL-FETs, the slow formation of EDLs and the oxidation reaction at the interface between the surface of the TiO2 film and the electrolytes cause unideal FET properties. In the optimized IL and IG TiO2-EDL-FETs, the driving gate voltage is less than 1 V and the ON/OFF ratios of the transfer characteristics are about 1×104 at RT, and the nearly metallic state is realized at the interface purely by applying a gate voltage.

Synthesis and magnetic properties of the thin film exchange spring system of MnBi/FeCo

NASA Astrophysics Data System (ADS)

Sabet, S.; Hildebrandt, E.; Alff, L.

2017-10-01

Manganese bismuth thin films with a nominal thickness of ∼40 nm were grown at room temperature onto quartz glass substrate in a DC magnetron sputtering unit. In contrast to the usual multilayer approach, the MnBi films were deposited using a single sputtering target with a stoichiometry of Mn55Bi45 (at. %). A subsequent in-situ annealing step was performed in vacuum in order to form the ferromagnetic LTP of MnBi. X-ray diffraction confirmed the formation of a textured LTP MnBi hard phase after annealing at 330 °C. This film shows a maximum saturation magnetization of 530 emu/cm3, high out-of-plane coercivity of 15 kOe induced by unreacted bismuth. The exchange coupling effect was investigated by deposition of a second layer of FeCo with 1 nm and 2 nm thickness onto the LTP MnBi films. The MnBi/FeCo double layer showed as expected higher saturation magnetization with increasing thickness of the FeCo layer while the coercive field remained constant. The fabrication of the MnBi/FeCo double layer for an exchange spring magnet was facilitated by deposition from a single stoichiometric target.

Nonlocal Poisson-Fermi double-layer models: Effects of nonuniform ion sizes on double-layer structure

NASA Astrophysics Data System (ADS)

Xie, Dexuan; Jiang, Yi

2018-05-01

This paper reports a nonuniform ionic size nonlocal Poisson-Fermi double-layer model (nuNPF) and a uniform ionic size nonlocal Poisson-Fermi double-layer model (uNPF) for an electrolyte mixture of multiple ionic species, variable voltages on electrodes, and variable induced charges on boundary segments. The finite element solvers of nuNPF and uNPF are developed and applied to typical double-layer tests defined on a rectangular box, a hollow sphere, and a hollow rectangle with a charged post. Numerical results show that nuNPF can significantly improve the quality of the ionic concentrations and electric fields generated from uNPF, implying that the effect of nonuniform ion sizes is a key consideration in modeling the double-layer structure.

Dynamical features and electric field strengths of double layers driven by currents. [in auroras

NASA Technical Reports Server (NTRS)

Singh, N.; Thiemann, H.; Schunk, R. W.

1985-01-01

In recent years, a number of papers have been concerned with 'ion-acoustic' double layers. In the present investigation, results from numerical simulations are presented to show that the shapes and forms of current-driven double layers evolve dynamically with the fluctuations in the current through the plasma. It is shown that double layers with a potential dip can form even without the excitation of ion-acoustic modes. Double layers in two-and one-half-dimensional simulations are discussed, taking into account the simulation technique, the spatial and temporal features of plasma, and the dynamical behavior of the parallel potential distribution. Attention is also given to double layers in one-dimensional simulations, and electrical field strengths predicted by two-and one-half-dimensional simulations.

Convective Differentiation of the Earth's Mantle

NASA Astrophysics Data System (ADS)

Hansen, U.; Schmalzl, J.; Stemmer, K.

2007-05-01

The differentiation of the Earth is likely to be influenced by convective motions within the early mantle. Double- diffusive convection (d.d.c), driven by thermally and compositionally induced density differences is considered as a vital mechanism behind the dynamic differentiation of the early mantle.. We demonstrate that d.d.c can lead to layer formation on a planetary scale in the diffusive regime where composition stabilizes the system whil heat provides the destabilizing force. Choosing initial conditions in which a stable compositional gradient overlies a hot reservoir we mimic the situation of a planet in a phase after core formation. Differently from earlier studies we fixed the temperature rather than the heat flux at the lower boundary, resembling a more realistic condition for the core-mantle boundary. We have carried out extended series of numerical experiments, ranging from 2D calculations in constant viscosity fluids to fully 3D experiments in spherical geometry with strongly temperature dependent viscosity. The buoyancy ratio R and the Lewis number Le are the important dynamical parameters. In all scenarios we could identify a parameter regime where the non-layered initial structure developed into a state consisting of several, mostly two layers. Initially plumes from the bottom boundary homogenize a first layer which subsequently thickens. The bottom layer heats up and then convection is initiated in the top layer. This creates dynamically (i.e. without jump in the material behavior) a stack of separately convecting layers. The bottom layer is significantly thicker than the top layer. Strongly temperature dependent viscosity leads to a more complex evolution The formation of the bottom layer is followed by the generation of several layers on top. Finally the uppermost layer starts to convect. In general, the multilayer structure collapses into a two layer system. We employed a numerical technique, allowing for a diffusion free treatment of the compositional field. In each case a similar evolution has been observed. This indicates that a temporary formation of layered structures in planetary interiors is a typical phenomenon. Moreover, in this scenario, plate tectonics appears only in later stages of the evolution.

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

Bolotov, V. V.; Knyazev, E. V.; Ponomareva, I. V.

The oxidation of mesoporous silicon in a double-layer “macroporous silicon–mesoporous silicon” structure is studied. The morphology and dielectric properties of the buried insulating layer are investigated using electron microscopy, ellipsometry, and electrical measurements. Specific defects (so-called spikes) are revealed between the oxidized macropore walls in macroporous silicon and the oxidation crossing fronts in mesoporous silicon. It is found that, at an initial porosity of mesoporous silicon of 60%, three-stage thermal oxidation leads to the formation of buried silicon-dioxide layers with an electric-field breakdown strength of E{sub br} ~ 10{sup 4}–10{sup 5} V/cm. Multilayered “porous silicon-on-insulator” structures are shown to bemore » promising for integrated chemical micro- and nanosensors.« less

The design and performance of the nano-carbon based double layers flexible coating for tunable and high-efficiency microwave absorption

NASA Astrophysics Data System (ADS)

Zhang, Danfeng; Hao, Zhifeng; Qian, Yannan; Zeng, Bi; Zhu, Haiping; Wu, Qibai; Yan, Chengjie; Chen, Muyu

2018-05-01

Nanocarbon-based materials are outstanding microwave absorbers with good dielectric properties. In this study, double-layer silicone resin flexible absorbing coatings, composed of carbon-coated nickel nanoparticles (Ni@C) and carbon nanotubes (CNTs), with low loading and a total thickness of 2 mm, were prepared. The reflection loss (RL) of the double-layer absorbing coatings has measured for frequencies between 2 and 18 GHz using the Arch reflecting testing method. The effects of the thickness and electromagnetic parameters of each layer and of the layer sequence on the absorbing properties were investigated. It is found that the measured bandwidth (RL ≤ - 10 dB) of the optimum double-layer structure in our experiment range achieves 3.70 GHz. The results indicated that the double coating structure composed of different materials has greater synergistic absorption effect on impedance matching than that of same materials with different loading. The maximum RL of S1 (5 wt% CNTs)/S3 (60 wt% Ni@C) double-layer absorbing coating composed of different materials (S1 and S3) was larger than the one achieved using either S1 or S3 alone with the same thickness. This was because double-layer coating provided a suitable matching layer and improve the interfacial impedance. It was also shown that absorbing peak value and frequency position can be adjusted by double-layer coating structure.

In Situ Formation of Decavanadate-Intercalated Layered Double Hydroxide Films on AA2024 and their Anti-Corrosive Properties when Combined with Hybrid Sol Gel Films

PubMed Central

Wu, Junsheng; Peng, Dongdong; He, Yuntao; Du, Xiaoqiong; Zhang, Zhan; Zhang, Bowei; Li, Xiaogang; Huang, Yizhong

2017-01-01

A layered double hydroxide (LDH) film was formed in situ on aluminum alloy 2024 through a urea hydrolysis method, and a decavanadate-intercalated LDH (LDH-V) film fabricated through the dip coating method. The microstructural and morphological characteristics were investigated by scanning electron microscopy (SEM). The corrosion-resistant performance was analyzed by electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SECM), and a salt-spray test (SST).The SEM results showed that a complete and defect-free surface was formed on the LDH-VS film. The anticorrosion results revealed that the LDH-VS film had better corrosion-resistant properties than the LDH-S film, especially long-term corrosion resistance. The mechanism of corrosion protection was proposed to consist of the self-healing effect of the decavanadate intercalation and the shielding effect of the sol-gel film. PMID:28772785

Reduction of biselenites into polyselenides in interlayer space of layered double hydroxides

NASA Astrophysics Data System (ADS)

Kim, Myeong Shin; Lee, Yongju; Park, Yong-Min; Cha, Ji-Hyun; Jung, Duk-Young

2018-06-01

A selenous acid (H2SeO3) precursor was intercalated as biselenite (HSeO3-) ions into the interlayer gallery of carbonated magnesium aluminum layered double hydroxide (MgAl-LDH) in aqueous solution. Reduction reaction of selenous ions by aqueous hydrazine solution produced polyselenide intercalated LDHs which were consecutively exchanged with iodide through redox reaction under iodine vapor. The polyselenide containing LDHs adsorbed iodine vapor spontaneously and triiodide was incorporated in the interlayer space followed by formation of selenium polycrystalline phase. Two dimensional framework of MgAl-LDH is strong enough to resist against the reducing power of hydrazine as well as oxidation condition of iodine. The SEM data demonstrated that the shapes of LDH polycrystalline have little changed after the above redox reactions. The polyselenide and iodide LDH products were analyzed by XRD, Infrared and Raman spectra which strongly suggested the horizontal arrangement of polyselenide and triiodide in gallery space of LDHs.

Synthesis and adsorption properties of flower-like layered double hydroxide by a facile one-pot reaction with an eggshell membrane as assistant

NASA Astrophysics Data System (ADS)

Li, Songnan; Zhang, Jiawei; Jamil, Saba; Cai, Qinghai; Zang, Shuying

In this paper, flower-like layered double hydroxides were synthesized with eggshell membrane assistant. The as-prepared samples were characterized by a series of techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermal gravity-differential thermal analysis and Nitrogen sorption/desorption. The resulting layered double hydroxides were composed of nanoplates with edge-to-face particle interactions. The specific surface area and total pore volume of the as-prepared flower-like layered double hydroxides were 160m2/g and 0.65m3/g, respectively. The adsorption capacity of flower-like layered double hydroxides to Congo Red was 258mg/g, which was higher than that of layered double hydroxides synthesized by the traditional method.

Effects of NAA and BAP, double-layered media, and light distance on in vitro regeneration of Nelumbo nucifera Gaertn. (lotus), an aquatic edible plant.

PubMed

Mahmad, Noraini; Taha, Rosna Mat; Othman, Rashidi; Saleh, Azani; Hasbullah, Nor Azlina; Elias, Hashimah

2014-01-01

In vitro direct regeneration of Nelumbo nucifera Gaertn. was successfully achieved from immature explants (yellow plumule) cultured on a solid MS media supplemented with combinations of 0.5 mg/L BAP and 1.5 mg/L NAA which resulted in 16.00 ± 0.30 number of shoots per explant and exhibited a new characteristic of layered multiple shoots, while normal roots formed on the solid MS basal media. The double-layered media gave the highest number of shoots per explant with a ratio of 2 : 1 (liquid to solid) with a mean number of 16.67 ± 0.23 shoots per explant with the formation of primary and secondary roots from immature explants. In the study involving light distance, the tallest shoot (16.67 ± 0.23 mm) obtained from the immature explants was at a light distance of 200 mm from the source of inflorescent light (1000 lux). The plantlets were successfully acclimatized in clay loam soil after 8 months being maintained under in vitro conditions.

Electron kinetics at the plasma interface

NASA Astrophysics Data System (ADS)

Bronold, Franz Xaver; Fehske, Holger; Pamperin, Mathias; Thiessen, Elena

2018-05-01

The most fundamental response of an ionized gas to a macroscopic object is the formation of the plasma sheath. It is an electron depleted space charge region, adjacent to the object, which screens the object's negative charge arising from the accumulation of electrons from the plasma. The plasma sheath is thus the positively charged part of an electric double layer whose negatively charged part is inside the wall. In the course of the Transregional Collaborative Research Center SFB/TRR24 we investigated, from a microscopic point of view, the elementary charge transfer processes responsible for the electric double layer at a floating plasma-wall interface and made first steps towards a description of the negative part of the layer inside the wall. Below we review our work in a colloquial manner, describe possible extensions, and identify key issues which need to be resolved to make further progress in the understanding of the electron kinetics across plasma-wall interfaces. Contribution to the Topical Issue "Fundamentals of Complex Plasmas", edited by Jürgen Meichsner, Michael Bonitz, Holger Fehske, Alexander Piel.

Tribological Properties of TiO2/SiO2 Double Layer Coatings Deposited on CP-Ti

NASA Astrophysics Data System (ADS)

Çomakli, O.; Yazici, M.; Yetim, T.; Yetim, A. F.; Çelik, A.

In the present paper, the influences of different double layer on wear and scratch performances of commercially pure Titanium (CP-Ti) were investigated. TiO2/SiO2 and SiO2/TiO2 double layer coatings were deposited on CP-Ti by sol-gel dip coating process and calcined at 750∘C. The phase structure, cross-sectional morphology, composition, wear track morphologies, adhesion properties, hardness and roughness of uncoated and coated samples were characterized with X-ray diffraction, scanning electron microscopy (SEM), nano-indentation technique, scratch tester and 3D profilometer. Also, the tribological performances of all samples were investigated by a pin-on-disc tribo-tester against Al2O3 ball. Results showed that hardness, elastic modulus and adhesion resistance of double layer coated samples were higher than untreated CP-Ti. It was found that these properties of TiO2/SiO2 double layer coatings have higher than SiO2/TiO2 double layer coating. Additionally, the lowest friction coefficient and wear rates were obtained from TiO2/SiO2 double layer coatings. Therefore, it was seen that phase structure, hardness and film adhesion are important factors on the tribological properties of double layer coatings.

Preparation and properties of chrome-free colored Ti/Zr based conversion coating on aluminum alloy

NASA Astrophysics Data System (ADS)

Yi, AiHua; Li, WenFang; Du, Jun; Mu, SongLin

2012-06-01

A golden conversion coating on the surface of aluminum alloy was prepared by adding tannic acid and coating-forming accelerator in the treatment solution containing titanium and zirconium ions. The growth process, main component and corrosion resistance of the conversion coating were characterized by EDS, SEM, XRD, XPS, FIIR and electrochemical workstation. The results showed that the main components of the conversion coating were Na3AlF6 and the conversion coating owns a double-layer structure. The outer layer consists of metal-organic complex and the inner layer is mainly made up of Na3AlF6. The mechanism of the formation of the golden conversion coating can be deemed as nucleation, growth of Na3AlF6 crystal and formation of metal-organic complex. In potentiodynamic polarization test, the corrosion current density decreases to 0.283 μA cm-2 from 5.894 μA cm-2, which indicates an obvious improvement of corrosion resistance.

Polysulfide intercalated layered double hydroxides for metal capture applications

DOEpatents

Kanatzidis, Mercouri G.; Ma, Shulan

2017-04-04

Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

Capacitance of carbon-based electrical double-layer capacitors.

PubMed

Ji, Hengxing; Zhao, Xin; Qiao, Zhenhua; Jung, Jeil; Zhu, Yanwu; Lu, Yalin; Zhang, Li Li; MacDonald, Allan H; Ruoff, Rodney S

2014-01-01

Experimental electrical double-layer capacitances of porous carbon electrodes fall below ideal values, thus limiting the practical energy densities of carbon-based electrical double-layer capacitors. Here we investigate the origin of this behaviour by measuring the electrical double-layer capacitance in one to five-layer graphene. We find that the capacitances are suppressed near neutrality, and are anomalously enhanced for thicknesses below a few layers. We attribute the first effect to quantum capacitance effects near the point of zero charge, and the second to correlations between electrons in the graphene sheet and ions in the electrolyte. The large capacitance values imply gravimetric energy storage densities in the single-layer graphene limit that are comparable to those of batteries. We anticipate that these results shed light on developing new theoretical models in understanding the electrical double-layer capacitance of carbon electrodes, and on opening up new strategies for improving the energy density of carbon-based capacitors.

Subsurface volatile content of martian double-layer ejecta (DLE) craters

USGS Publications Warehouse

Viola, Donna; McEwen, Alfred S.; Dundas, Colin M.; Byrne, Shane

2017-01-01

Excess ice is widespread throughout the martian mid-latitudes, particularly in Arcadia Planitia, where double-layer ejecta (DLE) craters also tend to be abundant. In this region, we observe the presence of thermokarstically-expanded secondary craters that likely form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. The presence of these expanded craters shows that excess ice is still preserved within the adjacent terrain. Here, we focus on a 15-km DLE crater that contains abundant superposed expanded craters in order to study the distribution of subsurface volatiles both at the time when the secondary craters formed and, by extension, remaining today. To do this, we measure the size distribution of the superposed expanded craters and use topographic data to calculate crater volumes as a proxy for the volumes of ice lost to sublimation during the expansion process. The inner ejecta layer contains craters that appear to have undergone more expansion, suggesting that excess ice was most abundant in that region. However, both of the ejecta layers had more expanded craters than the surrounding terrain. We extrapolate that the total volume of ice remaining within the entire ejecta deposit is as much as 74 km3 or more. The variation in ice content between the ejecta layers could be the result of (1) volatile preservation from the formation of the DLE crater, (2) post-impact deposition in the form of ice lenses; or (3) preferential accumulation or preservation of subsequent snowfall. We have ruled out (2) as the primary mode for ice deposition in this location based on inconsistencies with our observations, though it may operate in concert with other processes. Although none of the existing DLE formation hypotheses are completely consistent with our observations, which may merit a new or modified mechanism, we can conclude that DLE craters contain a significant quantity of excess ice today.

A Prospective Randomized Clinical Trial of Single vs. Double Layer Closure of Hysterotomy at the Time of Cesarean Delivery: The Effect on Uterine Scar Thickness.

PubMed

Bamberg, Christian; Dudenhausen, Joachim W; Bujak, Verena; Rodekamp, Elke; Brauer, Martin; Hinkson, Larry; Kalache, Karim; Henrich, Wolfgang

2018-06-01

 We undertook a randomized clinical trial to examine the outcome of a single vs. a double layer uterine closure using ultrasound to assess uterine scar thickness.  Participating women were allocated to one of three uterotomy suture techniques: continuous single layer unlocked suturing, continuous locked single layer suturing, or double layer suturing. Transvaginal ultrasound of uterine scar thickness was performed 6 weeks and 6 - 24 months after Cesarean delivery. Sonographers were blinded to the closure technique.  An "intent-to-treat" and "as treated" ANOVA analysis included 435 patients (n = 149 single layer unlocked suturing, n = 157 single layer locked suturing, and n = 129 double layer suturing). 6 weeks postpartum, the median scar thickness did not differ among the three groups: 10.0 (8.5 - 12.3 mm) single layer unlocked vs. 10.1 (8.2 - 12.7 mm) single layer locked vs. 10.8 (8.1 - 12.8 mm) double layer; (p = 0.84). At the time of the second follow-up, the uterine scar was not significantly (p = 0.06) thicker if the uterus had been closed with a double layer closure 7.3 (5.7 - 9.1 mm), compared to single layer unlocked 6.4 (5.0 - 8.8 mm) or locked suturing techniques 6.8 (5.2 - 8.7 mm). Women who underwent primary or elective Cesarean delivery showed a significantly (p = 0.03, p = 0.02, "as treated") increased median scar thickness after double layer closure vs. single layer unlocked suture.  A double layer closure of the hysterotomy is associated with a thicker myometrium scar only in primary or elective Cesarean delivery patients. © Georg Thieme Verlag KG Stuttgart · New York.

PPy/PMMA/PEG-based sensor for low-concentration acetone detection

NASA Astrophysics Data System (ADS)

Daneshkhah, A.; Shrestha, S.; Agarwal, M.; Varahramyan, K.

2014-05-01

A polymer pellet-based sensor device comprised of polypyrrole (PPy), polymethyl methacrylate (PMMA) and polyethylene glycol (PEG), its fabrication methods, and the experimental results for low-concentration acetone detection are presented. The design consists of a double layer pellet, where the top layer consists of PPy/PMMA and the bottom layer is composed of PPy/PMMA/PEG. Both sets of material compositions are synthesized by readily realizable chemical polymerization techniques. The mechanism of the sensor operation is based on the change in resistance of PPy and the swelling of PMMA when exposed to acetone, thereby changing the resistance of the layers. The resistances measured on the two layers, and across the pellet, are taken as the three output signals of the sensor. Because the PPy/PMMA and PPy/PMMA/PEG layers respond differently to acetone, as well as to other volatile organic compounds, it is demonstrated that the three output signals can allow the presented sensor to have a better sensitivity and selectivity than previously reported devices. Materials characterizations show formation of new composite with PPy/PMMA/PEG. Material response at various concentrations of acetone was conducted using quartz crystal microbalance (QCM). It was observed that the frequency decreased by 98 Hz for 290 ppm of acetone and by 411 Hz for 1160 ppm. Experimental results with a double layer pellet of PPy/PMMA and PPy/PMMA/PEG show an improved selectivity of acetone over ethanol. The reported acetone sensor is applicable for biomedical and other applications.

Magnetoelectric effect in concentric quantum rings induced by shallow donor

NASA Astrophysics Data System (ADS)

Escorcia, R.; García, L. F.; Mikhailov, I. D.

2018-05-01

We study the alteration of the magnetic and electric properties induced by the off-axis donor in a double InAs/GaAs concentric quantum ring. To this end we consider a model of an axially symmetrical ring-like nanostructure with double rim, in which the thickness of the InAs thin layer is varied smoothly in the radial direction. The energies and of contour plots of the density of charge for low-lying levels we find by using the adiabatic approximation and the double Fourier-Bessel series expansion method and the Kane model. Our results reveal a possibility of the formation of a giant dipole momentum induced by the in-plane electric field, which in addition can be altered by of the external magnetic field applied along the symmetry axis.

Proliferative defects and formation of a double cortex in mice lacking Mltt4 and Cdh2 in the dorsal telencephalon.

PubMed

Gil-Sanz, Cristina; Landeira, Bruna; Ramos, Cynthia; Costa, Marcos R; Müller, Ulrich

2014-08-06

Radial glial cells (RGCs) in the ventricular neuroepithelium of the dorsal telencephalon are the progenitor cells for neocortical projection neurons and astrocytes. Here we show that the adherens junction proteins afadin and CDH2 are critical for the control of cell proliferation in the dorsal telencephalon and for the formation of its normal laminar structure. Inactivation of afadin or CDH2 in the dorsal telencephalon leads to a phenotype resembling subcortical band heterotopia, also known as "double cortex," a brain malformation in which heterotopic gray matter is interposed between zones of white matter. Adherens junctions between RGCs are disrupted in the mutants, progenitor cells are widely dispersed throughout the developing neocortex, and their proliferation is dramatically increased. Major subtypes of neocortical projection neurons are generated, but their integration into cell layers is disrupted. Our findings suggest that defects in adherens junctions components in mice massively affects progenitor cell proliferation and leads to a double cortex-like phenotype. Copyright © 2014 the authors 0270-6474/14/3410475-13$15.00/0.

Laboratory observation of multiple double layer resembling space plasma double layer

NASA Astrophysics Data System (ADS)

Alex, Prince; Arumugam, Saravanan; Sinha, Suraj

2017-10-01

Perceptible double layer consisting of more than one layers were produced in laboratory using a double discharge plasma setup. The confinement of oppositely charged particles in each layer with sharply defined luminous boarder is attributed to the self-organization scenario. This structure is generated in front of a positively biased electrode when the electron drift velocity (νd) exceeds 1.3 times the electron thermal velocity (νte) . Stable multiple double layer structures were observed only between 1.3 νte <=νd <= 3 νte. At νd = 1.3 νte, oscillations were excited in the form of large amplitude burst followed by a high frequency stable oscillation. Beyond νd = 3 νte, multiple double layer begins to collapse which is characterized by an emergence in turbulence. Long range dependence in the corresponding electrostatic potential fluctuations indicates the role of self-organized criticality in the emergence of turbulence. The algebraic decaying tale of the autocorrelation function and power law behavior in the power spectrum are consistent with the observation.

Double layers and circuits in astrophysics

NASA Technical Reports Server (NTRS)

Alfven, H.

1986-01-01

A simple circuit is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the Sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object. It is suggested that X-ray and gamma-ray bursts may be due to exploding double layers (although annihilation is an alternative energy source). The way the most used textbooks in astrophysics treat concepts like double layers, critical velocity, pinch effects and circuits was studied. It is found that students using these textbooks remain essentially ignorant of even the existence of these, although some of the phenomena were discovered 50 yr ago.

Evaluation of molecular dynamics simulation methods for ionic liquid electric double layers.

PubMed

Haskins, Justin B; Lawson, John W

2016-05-14

We investigate how systematically increasing the accuracy of various molecular dynamics modeling techniques influences the structure and capacitance of ionic liquid electric double layers (EDLs). The techniques probed concern long-range electrostatic interactions, electrode charging (constant charge versus constant potential conditions), and electrolyte polarizability. Our simulations are performed on a quasi-two-dimensional, or slab-like, model capacitor, which is composed of a polarizable ionic liquid electrolyte, [EMIM][BF4], interfaced between two graphite electrodes. To ensure an accurate representation of EDL differential capacitance, we derive new fluctuation formulas that resolve the differential capacitance as a function of electrode charge or electrode potential. The magnitude of differential capacitance shows sensitivity to different long-range electrostatic summation techniques, while the shape of differential capacitance is affected by charging technique and the polarizability of the electrolyte. For long-range summation techniques, errors in magnitude can be mitigated by employing two-dimensional or corrected three dimensional electrostatic summations, which led to electric fields that conform to those of a classical electrostatic parallel plate capacitor. With respect to charging, the changes in shape are a result of ions in the Stern layer (i.e., ions at the electrode surface) having a higher electrostatic affinity to constant potential electrodes than to constant charge electrodes. For electrolyte polarizability, shape changes originate from induced dipoles that soften the interaction of Stern layer ions with the electrode. The softening is traced to ion correlations vertical to the electrode surface that induce dipoles that oppose double layer formation. In general, our analysis indicates an accuracy dependent differential capacitance profile that transitions from the characteristic camel shape with coarser representations to a more diffuse profile with finer representations.

Superconductivity in ion-beam-mixed layered Au-Si thin films

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

Jisrawi, N.M.; McLean, W.L.; Stoffel, N.G.

The superconducting properties of thin films made by mixing alternating layers of Au and Si using ion-beam bombardment correlate with the formation of metastable metallic phases in what is otherwise a simple eutectic system. Transmission-electron-microscopy measurements reveal the superconducting phases to be amorphous. Compound formation and the nature of Au-Si bonding in these metastable phases are demonstrated from x-ray photoelectron spectroscopy and from a previous study of x-ray-absorption spectroscopy. After mixing with a beam of Xe ions, multilayered films with an average nominal composition Au{sub {ital x}}Si{sub 1{minus}{ital x}}, where {ital x}=0.2, 0.4, 0.5, 0.72, and 0.8, exhibited superconducting transitionmore » temperatures in the range 0.2--1.2 K. A double transition feature in the magnetic field dependence of the resistivity is attributed to the formation of more than one metastable metallic phase in the same sample as the ion dose increases.« less

Study on dynamic deformation synchronized measurement technology of double-layer liquid surfaces

NASA Astrophysics Data System (ADS)

Tang, Huiying; Dong, Huimin; Liu, Zhanwei

2017-11-01

Accurate measurement of the dynamic deformation of double-layer liquid surfaces plays an important role in many fields, such as fluid mechanics, biomechanics, petrochemical industry and aerospace engineering. It is difficult to measure dynamic deformation of double-layer liquid surfaces synchronously for traditional methods. In this paper, a novel and effective method for full-field static and dynamic deformation measurement of double-layer liquid surfaces has been developed, that is wavefront distortion of double-wavelength transmission light with geometric phase analysis (GPA) method. Double wavelength lattice patterns used here are produced by two techniques, one is by double wavelength laser, and the other is by liquid crystal display (LCD). The techniques combine the characteristics such as high transparency, low reflectivity and fluidity of liquid. Two color lattice patterns produced by laser and LCD were adjusted at a certain angle through the tested double-layer liquid surfaces simultaneously. On the basis of the refractive indexes difference of two transmitted lights, the double-layer liquid surfaces were decoupled with GPA method. Combined with the derived relationship between phase variation of transmission-lattice patterns and out-of plane heights of two surfaces, as well as considering the height curves of the liquid level, the double-layer liquid surfaces can be reconstructed successfully. Compared with the traditional measurement method, the developed method not only has the common advantages of the optical measurement methods, such as high-precision, full-field and non-contact, but also simple, low cost and easy to set up.

Improved Mobility and Bias Stability of Thin Film Transistors Using the Double-Layer a-InGaZnO/a-InGaZnO:N Channel.

PubMed

Yu, H; Zhang, L; Li, X H; Xu, H Y; Liu, Y C

2016-04-01

The amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) were demonstrated based on a double-layer channel structure, where the channel is composed of an ultrathin nitro-genated a-IGZO (a-IGZO:N) layer and an undoped a-IGZO layer. The double-layer channel device showed higher saturation mobility and lower threshold-voltage shift (5.74 cm2/Vs, 2.6 V) compared to its single-layer counterpart (0.17 cm2/Vs, 7.23 V). The improvement can be attributed to three aspects: (1) improved carrier transport properties of the channel by the a-IGZO:N layer with high carrier mobility and the a-IGZO layer with high carrier concentration, (2) reduced interfacial trap density between the active channel and the gate insulator, and (3) higher surface flatness of the double-layer channel. Our study reveals key insights into double-layer channel, involving selecting more suitable electrical property for back-channel layer and more suitable interface modification for active layer. Meanwhile, room temperature fabrication amorphous TFTs offer certain advantages on better flexibility and higher uniformity over a large area.

Method of making a high performance ultracapacitor

DOEpatents

Farahmandi, C. Joseph; Dispennette, John M.

2000-07-26

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

Aluminum-carbon composite electrode

DOEpatents

Farahmandi, C. Joseph; Dispennette, John M.

1998-07-07

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

Aluminum-carbon composite electrode

DOEpatents

Farahmandi, C.J.; Dispennette, J.M.

1998-07-07

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

Double layer drainage performance of porous asphalt pavement

NASA Astrophysics Data System (ADS)

Ji, Yangyang; Xie, Jianguang; Liu, Mingxi

2018-06-01

In order to improve the design reliability of the double layer porous asphalt pavement, the 3D seepage finite element method was used to study the drainage capacity of double layer PAC pavements with different geometric parameters. It revealed that the effect of pavement drainage length, slope, permeability coefficient and structure design on the drainage capacity. The research of this paper can provide reference for the design of double layer porous asphalt pavement in different rainfall intensity areas, and provide guides for the related engineering design.

Evolution of Multiple Double Layer in Glow discharge and its inherent Properties

NASA Astrophysics Data System (ADS)

Alex, Prince; A, Saravanan; Sinha, Suraj

2016-10-01

Formation and evolution of multiple anodic double layers (MADLs) were experimentally studied in glow discharge plasma. The boundary condition for the existence of MADL was identified in terms of threshold bias and ambient working pressure. The MADL formation is accompanied by an explosive growth in anode current and consequent current-voltage characteristics follows a hysteresis loop. The analysis yield that stable MADLs is only observed when the control voltage V2 is between a certain critical values (Vq > νte MADL completely transforms to an intense high current carrying unstable anode glow. The floating potential analysis carried out using three axially positioned electrostatic probes shows a bipolar signature of DL with as the control parameter is varied. The floating potential analysis also shows that hysteresis arises due to the difference in magnitude of electric field required to align the space charges in the DL sheet at the control voltage changes forward and backward. The effect of pressure on MADL indicates that the MADL structure advances towards anode surface as the pressure is increases. The power dumped (W) in the MADL is estimated to decrease with increase in pressure while the same increase in the anode glow.

Crystal chemistry of a Ba-dominant analogue of hydrodelhayelite and natural ion-exchange transformations in double- and triple-layer phyllosilicates in post-volcanic systems of the Eifel region, Germany

NASA Astrophysics Data System (ADS)

Zubkova, N. V.; Chukanov, N. V.; Pekov, I. V.; Turchkova, A. G.; Lykova, I. S.; Schüller, W.; Ternes, B.; Pushcharovsky, D. Yu.

2016-12-01

A Ba-dominant (Ba > K) analogue of hydrodelhayelite (BDAH) from Löhley (Eifel Mts., Rhineland-Palatinate, Germany) and Ba-enriched varieties of related double- and triple-layer phyllosilicates from Eifel are studied. The crystal structure of BDAH was solved by direct methods and refined to R = 0.0698 [1483 unique reflections with I > 2σ( I)]. It is orthorhombic, Pmmn, a = 23.9532(9), b = 7.0522(3), c = 6.6064(3) Å, V = 1115.97(8) Å3, Z = 2. The structure is based upon delhayelite-type double-layer tetrahedral blocks [(Al,Si)4Si12O34(OH,O)4] connected by chains of (Ca,Fe)-centered octahedra. Ba2+ and subordinate K+ occur at partially vacant sites in zeolitic channels within the tetrahedral blocks. The crystal-chemical formula of BDAH is: (Ba0.42K0.34□0.24)(Ca0.88Fe0.12)2(□0.90Mg0.10)2[Si6(Al0.5Si0.5)2O17(OH0.71O0.29)2]ṡ6H2O. The formation of BDAH and Ba-rich varieties of altered delhayelite/fivegite, günterblassite and hillesheimite is considered as a result of leaching of Na, Cl, F and, partially, K and Ca accompanied with hydration and the capture of Ba as a result of natural ion exchange. These minerals are structurally a "bridge" between single-layer phyllosilicates and zeolites having the open three-dimensional tetrahedral Al-Si-O frameworks.

A one-dimensional Fickian model to predict the Ga depth profiles in three-stage Cu(In,Ga)Se{sub 2}

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

Rodriguez-Alvarez, H., E-mail: humberto.rodriguez@helmholtz-berlin.de; Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin; Mainz, R.

2014-05-28

We present a one-dimensional Fickian model that predicts the formation of a double Ga gradient during the fabrication of Cu(In,Ga)Se{sub 2} thin films by three-stage thermal co-evaporation. The model is based on chemical reaction equations, structural data, and effective Ga diffusivities. In the model, the Cu(In,Ga)Se{sub 2} surface is depleted from Ga during the deposition of Cu-Se in the second deposition stage, leading to an accumulation of Ga near the back contact. During the third deposition stage, where In-Ga-Se is deposited at the surface, the atomic fluxes within the growing layer are inverted. This results in the formation of amore » double Ga gradient within the Cu(In,Ga)Se{sub 2} layer and reproduces experimentally observed Ga distributions. The final shape of the Ga depth profile strongly depends on the temperatures, times and deposition rates used. The model is used to evaluate possible paths to flatten the marked Ga depth profile that is obtained when depositing at low substrate temperatures. We conclude that inserting Ga during the second deposition stage is an effective way to achieve this.« less

Characteristics of a-IGZO/ITO hybrid layer deposited by magnetron sputtering.

PubMed

Bang, Joon-Ho; Park, Hee-Woo; Cho, Sang-Hyun; Song, Pung-Keun

2012-04-01

Transparent a-IGZO (In-Ga-Zn-O) films have been actively studied for use in the fabrication of high-quality TFTs. In this study, a-IGZO films and a-IGZO/ITO double layers were deposited by DC magnetron sputtering under various oxygen flow rates. The a-IGZO films showed an amorphous structure up to 500 degrees C. The deposition rate of these films decreased with an increase in the amount of oxygen gas. The amount of indium atoms in the film was confirmed to be 11.4% higher than the target. The resistivity of double layer follows the rules for parallel DC circuits The maximum Hall mobility of the a-IGZO/ITO double layers was found to be 37.42 cm2/V x N s. The electrical properties of the double layers were strongly dependent on their thickness ratio. The IGZO/ITO double layer was subjected to compressive stress, while the ITO/IGZO double layer was subjected to tensile stress. The bending tolerance was found to depend on the a-IGZO thickness.

The Electrical Double Layer and Its Structure

NASA Astrophysics Data System (ADS)

Stojek, Zbigniew

At any electrode immersed in an electrolyte solution, a specific interfacial region is formed. This region is called the double layer. The electrical properties of such a layer are important, since they significantly affect the electrochemical measurements. In an electrical circuit used to measure the current that flows at a particular working electrode, the double layer can be viewed as a capacitor. Figure I.1.1 depicts this situation where the electrochemical cell is represented by an electrical circuit and capacitor C d corresponds to the differential capacity of the double layer. To obtain a desired potential at the working electrodes, the double-layer capacitor must be first appropriately charged, which means that a capacitive current, not related to the reduction or oxidation of the substrates, flows in the electrical circuit. While this capacitive current carries some information concerning the double layer and its structure, and in some cases can be used for analytical purposes, in general, it interferes with electrochemical investigations. A variety of methods are used in electrochemistry to depress, isolate, or filter the capacitive current.

DVD - digital versatile disks

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

Gaunt, R.

1997-05-01

An international standard has emerged for the first true multimedia format. Digital Versatile Disk (by its official name), you may know it as Digital Video Disks. DVD has applications in movies, music, games, information CD-ROMS, and many other areas where massive amounts of digital information is needed. Did I say massive amounts of data? Would you believe over 17 gigabytes on a single piece of plastic the size of an audio-CD? That`s the promise, at least, by the group of nine electronics manufacturers who have agreed to the format specification, and who hope to make this goal a reality bymore » 1998. In this major agreement, which didn`t come easily, the manufacturers will combine Sony and Phillip`s one side double-layer NMCD format with Toshiba and Matsushita`s double sided Super-Density disk. By Spring of this year, they plan to market the first 4.7 gigabyte units. The question is: Will DVD take off? Some believe that read-only disks recorded with movies will be about as popular as video laser disks. They say that until the eraseable/writable DVD arrives, the consumer will most likely not buy it. Also, DVD has a good market for replacement of CD- Roms. Back in the early 80`s, the international committee deciding the format of the audio compact disk decided its length would be 73 minutes. This, they declared, would allow Beethoven`s 9th Symphony to be contained entirely on a single CD. Similarly, today it was agreed that playback length of a single sided, single layer DVD would be 133 minutes, long enough to hold 94% of all feature-length movies. Further, audio can be in Dolby`s AC-3 stereo or 5.1 tracks of surround sound, better than CD-quality audio (16-bits at 48kHz). In addition, there are three to five language tracks, copy protection and parental ``locks`` for R rated movies. DVD will be backwards compatible with current CD-ROM and audio CD formats. Added versatility comes by way of multiple aspect rations: 4:3 pan-scan, 4:3 letterbox, and 16:9 widescreen. MPEG-2 is the selected image compression format, with full ITU Rec. 601 video resolution (72Ox480). MPEG-2 and AC-3 are also part of the U.S. high definition Advance Television standard (ATV). DVD has an average video bit rate of 3.5 Mbits/sec or 4.69Mbits/sec for image and sound. Unlike digital television transmission, which will use fixed length packets for audio and video, DVD will use variable length packets with a maximum throughput of more than 1OMbits/sec. The higher bit rate allows for less compression of difficult to encode material. Even with all the compression, narrow-beam red light lasers are required to significantly increase the physical data density of a platter by decreasing the size of the pits. This allows 4.7 gigabytes of data on a single sided, single layer DVD. The maximum 17 gigabyte capacity is achieved by employing two reflective layers on both sides of the disk. To read the imbedded layer of data, the laser`s focal length is altered so that the top layer pits are not picked up by the reader. It will be a couple of years before we have dual-layer, double-sided DVDS, and it will be achieved in four stages. The first format to appear will be the single sided, single layer disk (4.7 gigabytes). That will allow Hollywood to begin releasing DVD movie titles. DVD-ROM will be the next phase, allowing 4.7 gigabytes of CD-ROM-like content. The third stage will be write-once disks, and stage four will be rewritable disks. These last stages presents some issues which have yet to be resolved. For one, copyrighted materials may have some form of payment system, and there is the issue that erasable disks reflect less light than today`s DVDS. The problem here is that their data most likely will not be readable on earlier built players.« less

Effectiveness evaluation of double-layered satellite network with laser and microwave hybrid links based on fuzzy analytic hierarchy process

NASA Astrophysics Data System (ADS)

Zhang, Wei; Rao, Qiaomeng

2018-01-01

In order to solve the problem of high speed, large capacity and limited spectrum resources of satellite communication network, a double-layered satellite network with global seamless coverage based on laser and microwave hybrid links is proposed in this paper. By analyzing the characteristics of the double-layered satellite network with laser and microwave hybrid links, an effectiveness evaluation index system for the network is established. And then, the fuzzy analytic hierarchy process, which combines the analytic hierarchy process and the fuzzy comprehensive evaluation theory, is used to evaluate the effectiveness of the double-layered satellite network with laser and microwave hybrid links. Furthermore, the evaluation result of the proposed hybrid link network is obtained by simulation. The effectiveness evaluation process of the proposed double-layered satellite network with laser and microwave hybrid links can help to optimize the design of hybrid link double-layered satellite network and improve the operating efficiency of the satellite system.

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

PubMed Central

Nakayama, Hirokazu; Hayashi, Aki

2014-01-01

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids. PMID:25080007

Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition.

PubMed

Nakayama, Hirokazu; Hayashi, Aki

2014-07-30

The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

Advanced light-scattering materials: Double-textured ZnO:B films grown by LP-MOCVD

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Spadoni, A.; Antonaia, A.

2013-12-01

Double-textured ZnO:B layers with enhanced optical scattering in both short and long wavelength regions have been successfully fabricated using MOCVD technique through a three step process. Growth of double-textured structures has been induced by wet etching on polycrystalline ZnO surface. Our double-layer structure consists of a first ZnO:B layer wet etched and subsequently used as substrate for a second ZnO:B layer deposition. Polycrystalline ZnO:B layers were etched by utilizing diluted solutions of fluoridic acid (HF), chloridric acid (HCl) and phosphoric acid (H3PO4) and their effect on surface morphology modification was systematically investigated. The morphology of the second deposited ZnO layer strongly depended on the surface properties of the etched ZnO first layer. Growth of cauliflower-like texture was induced by protrusions presence on the HCl etched surface. Optimized double-layer structure shows a cauliflower-like double texture with higher RMS roughness and increased spectral haze values in both short and long wavelength regions, compared to conventional pyramidal-like single texture. Furthermore, this highly scattering structure preserves excellent optical and electrical properties.

Photobleachable Diazonium Salt-Phenolic Resin Two-Layer Resist System

NASA Astrophysics Data System (ADS)

Uchino, Shou-ichi; Iwayanagi, Takao; Hashimoto, Michiaki

1988-01-01

This article describes a new negative two-layer photoresist system formed by a simple, successive spin-coating method. An aqueous acetic acid solution of diazonium salt and poly(N-vinylpyrrolidone) is deposited so as to contact a phenolic resin film spin-coated on a silicon wafer. The diazonium salt diffuses into the phenolic resin layer after standing for several minutes. The residual solution on the phenolic resin film doped with diazonium salt is spun to form the diazonium salt-poly(N-vinylpyrrolidone) top layer. This forms a uniform two-layer resist without phase separation or striation. Upon UV exposure, the diazonium salt in the top layer bleaches to act as a CEL dye, while the diazonium salt in the bottom layer decomposes to cause insolubilization. Half μm line-and-space patterns are obtained with an i-line stepper using 4-diazo-N,N-dimethylaniline chloride zinc chloride double salt as the diazonium salt and a cresol novolac resin for the bottom polymer layer. The resist formation processes, insolubilization mechanism, and the resolution capability of the new two-layer resist are discussed.

Theory of multiple quantum dot formation in strained-layer heteroepitaxy

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

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

2016-07-11

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

Light scattering management of dye-sensitized solar cells based on double-layered photoanodes aided by uniform TiO{sub 2} aggregates

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

Bakhshayesh, A.M., E-mail: bakhshayesh@alum.sharif.edu

2016-01-15

Highlights: • A new architecture of double-layered TiO{sub 2} electrodes is presented. • The electrode contains two alternate layers of TiO{sub 2} nanoparticles and aggregates. • The aggregates layers are deposited onto the nanocrystalline layer. • The new design showed improved efficiency compared to conventional cells. - Abstract: This study presents a new double-layered TiO{sub 2} film containing a nanocrystalline under-layer and a uniform, sponge-like light scattering over-layer for dye-sensitized solar cells (DSCs) application. The over-layer is composed of 2-μm-diameter uniform aggregates, containing small nanoparticles with the average grain size of 20 nm. X-ray diffraction reveals that the light scatteringmore » layer has a mixture of anatase and rutile phases, whereas the nanocrystalline layer has a pure anatase phase. Ultraviolet–visible (UV–vis) spectra show that the light scattering layer has lower band gap energy than the nanocrystalline under-layer, extending the absorption of TiO{sub 2} into visible region. Diffuse reflectance spectroscopy demonstrates that the double-layered electrode enjoyed better light scattering ability. The double-layered DSC shows the highest power conversion efficiency of 7.69% and incident photon-to-current efficiency of 88% as a result of higher light harvesting and less recombination which is demonstrated by electrochemical impedance spectroscopy.« less

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.

Layer-by-layer assembly of patchy particles as a route to nontrivial structures

NASA Astrophysics Data System (ADS)

Patra, Niladri; Tkachenko, Alexei V.

2017-08-01

We propose a strategy for robust high-quality self-assembly of nontrivial periodic structures out of patchy particles and investigate it with Brownian dynamics simulations. Its first element is the use of specific patch-patch and shell-shell interactions between the particles, which can be implemented through differential functionalization of patched and shell regions with specific DNA strands. The other key element of our approach is the use of a layer-by-layer protocol that allows one to avoid the formation of undesired random aggregates. As an example, we design and self-assemble in silico a version of a double diamond lattice in which four particle types are arranged into bcc crystal made of four fcc sublattices. The lattice can be further converted to cubic diamond by selective removal of the particles of certain types. Our results demonstrate that by combining the directionality, selectivity of interactions, and the layer-by-layer protocol, a high-quality robust self-assembly can be achieved.

Layer-by-layer assembly of patchy particles as a route to nontrivial structures

DOE PAGES

Patra, Niladri; Tkachenko, Alexei V.

2017-08-02

Here, we propose a strategy for robust high-quality self-assembly of nontrivial periodic structures out of patchy particles and investigate it with Brownian dynamics simulations. Its first element is the use of specific patch-patch and shell-shell interactions between the particles, which can be implemented through differential functionalization of patched and shell regions with specific DNA strands. The other key element of our approach is the use of a layer-by-layer protocol that allows one to avoid the formation of undesired random aggregates. As an example, we design and self-assemble in silico a version of a double diamond lattice in which four particlemore » types are arranged into bcc crystal made of four fcc sublattices. The lattice can be further converted to cubic diamond by selective removal of the particles of certain types. These results demonstrate that by combining the directionality, selectivity of interactions, and the layer-by-layer protocol, a high-quality robust self-assembly can be achieved.« less

Capacitance of the Double Layer Formed at the Metal/Ionic-Conductor Interface: How Large Can It Be?

NASA Astrophysics Data System (ADS)

Skinner, Brian; Loth, M. S.; Shklovskii, B. I.

2010-03-01

The capacitance of the double layer formed at a metal/ionic-conductor interface can be remarkably large, so that the apparent width of the double layer is as small as 0.3 Å. Mean-field theories fail to explain such large capacitance. We propose an alternate theory of the ionic double layer which allows for the binding of discrete ions to their image charges in the metal. We show that at small voltages the capacitance of the double layer is limited only by the weak dipole-dipole repulsion between bound ions, and is therefore very large. At large voltages the depletion of bound ions from one of the capacitor electrodes triggers a collapse of the capacitance to the mean-field value.

The aluminum electrode in AlCl3-alkali-halide melts.

NASA Technical Reports Server (NTRS)

Holleck, G. L.; Giner, J.

1972-01-01

Passivation phenomena have been observed upon cathodic and anodic polarization of the Al electrode in AlCl3-KCl-NaCl melts between 100 and 160 C. They are caused by formation of a solid salt layer at the electrode surface resulting from concentration changes upon current flow. The anodic limiting currents increased with temperature and with decreasing AlCl3 content of the melt. Current voltage curves obtained on a rotating aluminum disk showed a linear relationship between the anodic limiting current and omega to the minus 1/2 power. Upon cathodic polarization, dendrite formation occurs at the Al electrode. The activation overvoltage in AlCl3-KCl-NaCl was determined by galvanostatic current step methods. An apparent exchange current density of 270 mA/sq cm at 130 C and a double layer capacity of 40 plus or minus 10 microfarad/sq cm were measured.

Enhancement of superconducting transition temperature in FeSe electric-double-layer transistor with multivalent ionic liquids

NASA Astrophysics Data System (ADS)

Miyakawa, Tomoki; Shiogai, Junichi; Shimizu, Sunao; Matsumoto, Michio; Ito, Yukihiro; Harada, Takayuki; Fujiwara, Kohei; Nojima, Tsutomu; Itoh, Yoshimitsu; Aida, Takuzo; Iwasa, Yoshihiro; Tsukazaki, Atsushi

2018-03-01

We report on an enhancement of the superconducting transition temperature (Tc) of the FeSe-based electric-double-layer transistor (FeSe-EDLT) by applying the multivalent oligomeric ionic liquids (ILs). The IL composed of dimeric cation (divalent IL) enables a large amount of charge accumulation on the surface of the FeSe ultrathin film, resulting in inducing electron-rich conduction even in a rather thick 10 nm FeSe channel. The onset Tc in FeSe-EDLT with the divalent IL is enhanced to be approaching about 50 K at the thin limit, which is about 7 K higher than that in EDLT with conventional monovalent ILs. The enhancement of Tc is a pronounced effect of the application of the divalent IL, in addition to the large capacitance, supposing preferable interface formation of ILs driven by geometric and/or Coulombic effect. The present finding strongly indicates that multivalent ILs are powerful tools for controlling and improving physical properties of materials.

Anomalous or regular capacitance? The influence of pore size dispersity on double-layer formation

NASA Astrophysics Data System (ADS)

Jäckel, N.; Rodner, M.; Schreiber, A.; Jeongwook, J.; Zeiger, M.; Aslan, M.; Weingarth, D.; Presser, V.

2016-09-01

The energy storage mechanism of electric double-layer capacitors is governed by ion electrosorption at the electrode surface. This process requires high surface area electrodes, typically highly porous carbons. In common organic electrolytes, bare ion sizes are below one nanometer but they are larger when we consider their solvation shell. In contrast, ionic liquid electrolytes are free of solvent molecules, but cation-anion coordination requires special consideration. By matching pore size and ion size, two seemingly conflicting views have emerged: either an increase in specific capacitance with smaller pore size or a constant capacitance contribution of all micro- and mesopores. In our work, we revisit this issue by using a comprehensive set of electrochemical data and a pore size incremental analysis to identify the influence of certain ranges in the pore size distribution to the ion electrosorption capacity. We see a difference in solvation of ions in organic electrolytes depending on the applied voltage and a cation-anion interaction of ionic liquids in nanometer sized pores.

Catalytic Graphitization for Preparation of Porous Carbon Material Derived from Bamboo Precursor and Performance as Electrode of Electrical Double-Layer Capacitor

NASA Astrophysics Data System (ADS)

Tsubota, Toshiki; Maguchi, Yuta; Kamimura, Sunao; Ohno, Teruhisa; Yasuoka, Takehiro; Nishida, Haruo

2015-12-01

The combination of addition of Fe (as a catalyst for graphitization) and CO2 activation (a kind of gaseous activation) was applied to prepare a porous carbon material from bamboo powder (a waste product of superheated steam treatment). Regardless of the heat treatment temperature, many macropores were successfully formed after the heating process by removal of Fe compounds. A turbostratic carbon structure was generated in the Fe-added sample heated at 850°C. It was confirmed that the added Fe acted as a template for pore formation. Moreover, it was confirmed that the added Fe acted as a catalyst for graphitization. The resulting electrochemical performance as the electrode of an electrical double-layer capacitor, as demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge testing, could be explained based on the graphitization and activation effects. Addition of Fe could affect the electrical properties of carbon material derived from bamboo.

Spreading of Electrolyte Drops on Charged Surfaces: Electric Double Layer Effects on Drop Dynamics

NASA Astrophysics Data System (ADS)

Bae, Kyeong; Sinha, Shayandev; Chen, Guang; Das, Siddhartha

2015-11-01

Drop spreading is one of the most fundamental topics of wetting. Here we study the spreading of electrolyte drops on charged surfaces. The electrolyte solution in contact with the charged solid triggers the formation of an electric double layer (EDL). We develop a theory to analyze how the EDL affects the drop spreading. The drop dynamics is studied by probing the EDL effects on the temporal evolution of the contact angle and the base radius (r). The EDL effects are found to hasten the spreading behaviour - this is commensurate to the EDL effects causing a ``philic'' tendency in the drops (i.e., drops attaining a contact angle smaller than its equilibrium value), as revealed by some of our recent papers. We also develop scaling laws to illustrate the manner in which the EDL effects make the r versus time (t) variation deviate from the well known r ~tn variation, thereby pinpointing the attainment of different EDL-mediated spreading regimes.

Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

PubMed

Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

2016-05-24

Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems.

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

NASA Astrophysics Data System (ADS)

Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

2016-01-01

A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

Double layer mixed matrix membrane adsorbers improving capacity and safety hemodialysis

NASA Astrophysics Data System (ADS)

Saiful; Borneman, Z.; Wessling, M.

2018-05-01

Double layer mixed matrix membranes adsorbers have been developed for blood toxin removal by embedding activated carbon into cellulose acetate macroporous membranes. The membranes are prepared by phase inversion method via water vapor induced phase separation followed by an immersion precipitation step. Double layer MMM consisting of an active support and a separating layer. The active support layer consists of activated carbon particles embedded in macroporous cellulose acetate; the separating layer consists of particle free cellulose acetate. The double layer membrane possess an open and interconnected macroporous structure with a high loading of activated carbon available for blood toxins removal. The MMM AC has a swelling degree of 6.5 %, porosity of 53 % and clean water flux of 800 Lm-2h-1bar-1. The prepared membranes show a high dynamic Creatinine (Crt) removal during hemodilysis process. The Crt removal by adsorption contributes to amore than 83 % of the total removal. The double layer adsorptive membrane proves hemodialysis membrane can integrated with adsorption, in which blood toxins are removed in one step.

Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

NASA Astrophysics Data System (ADS)

Deng, Z.; Wang, J.; Zheng, J.; Lin, Q.; Zhang, Y.; Wang, S.

2009-05-01

In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

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

Barahuie, Farahnaz; Hussein, Mohd Zobir, E-mail: mzobir@putra.upm.edu.my; Arulselvan, Palanisamy

A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the propertiesmore » of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro. - Highlights: • We intercalated chlorogenic into Zn/Al-layered double hydroxide by ion-exchange and coprecipitation methods. • The two methods gave nanocomposites with slightly different physico-chemical properties. • Chlorogenate-zinc aluminium layered double hydroxide nanohybrids have the potential to be used as a controlled release formulation. • The thermal stability of chlorogenic acid is markedly enhanced upon the intercalation process. • The inhibition of cancer cell growth is higher for nanohybrids than for free chlorogenic acid.« less

Enhanced electrochemical performance of Li-rich layered cathode materials via chemical activation of Li2MnO3 component and formation of spinel/carbon coating layer

NASA Astrophysics Data System (ADS)

Pang, Shengli; Xu, Kaijie; Wang, Yonggang; Shen, Xiangqian; Wang, Wenzhi; Su, Yanjing; Zhu, Meng; Xi, Xiaoming

2017-10-01

Li-rich layered oxides are promising cathode materials for advanced Li-ion batteries because of their high specific capacity and operating potential. In this work, the Li-rich layered oxide Li1·2Mn0·54Ni0·13Co0·13O2 (LMNC), is modified via a carbonization-reduction process (yielding the corresponding reduced compound denoted LMNC-R). Compared to the pristine oxide, LMNC-R delivers significantly enhanced initial discharge capacity/columbic efficiency, remarkably improved rate performance with an accelerated Li+ diffusion rate, and significantly increased capacity/voltage retention. The specific energy density and energy retention after 100 cycles increase from 378.2 Wh kg-1 and 47.7% for LMNC to 572.0 Wh kg-1 and 71.3%, respectively, for LMNC-R. The enhancement in the electrochemical performance of LMNC-R can be attributed to the synchronous formation of the oxygen non-stoichiometric Li2MnO3-δ component and to the carbon/spinel double coating layer in the material that resulted from the post-treatment process. Thus, the carbonization-reduction modification process can be used to tailor the structural evolution procedure and to suppress the metal ion dissolution of the Li-rich layered oxide during cycling.

Growth of multilayered polycrystalline reaction rims in the MgO-SiO2 system, part I: experiments

NASA Astrophysics Data System (ADS)

Gardés, E.; Wunder, B.; Wirth, R.; Heinrich, W.

2011-01-01

Growth of transport-controlled reaction layers between single crystals of periclase and quartz, and forsterite and quartz was investigated experimentally at 1.5 GPa, 1100°C to 1400°C, 5 min to 72 h under dry and melt-free conditions using a piston-cylinder apparatus. Starting assemblies consisting of Per | Qtz | Fo sandwiches produced polycrystalline double layers of forsterite and enstatite between periclase and quartz, and enstatite single layers between forsterite and quartz. The position of inert Pt-markers initially deposited at the interface of the reactants and inspection of mass balance confirmed that both layer-producing reactions are controlled by MgO diffusion, while SiO2 is relatively immobile. BSE and TEM imaging revealed thicknesses from 0.6 μm to 14 μm for double layers and from 0 to 6.8 μm for single layers. Both single and double layers displayed non-parabolic growth together with pronounced grain coarsening. Textural evolution and growth rates for each reaction are directly comparable. Forsterite-enstatite double layers are always wider than enstatite single layers, and the growth of enstatite in the double layer is slower than that in the single layer. In double layers, the enstatite/forsterite layer thickness ratio significantly increases with temperature, reflecting different MgO mobilities as temperature varies. Thus, thickness ratios in multilayered reaction zones may contain a record of temperature, but also that of any physico-chemical parameter that modifies the mobilities of the chemical components between the various layers. This potential is largely unexplored in geologically relevant systems, which calls for further experimental studies of multilayered reaction zones.

Double-Layer Gadolinium Zirconate/Yttria-Stabilized Zirconia Thermal Barrier Coatings Deposited by the Solution Precursor Plasma Spray Process

NASA Astrophysics Data System (ADS)

Jiang, Chen; Jordan, Eric H.; Harris, Alan B.; Gell, Maurice; Roth, Jeffrey

2015-08-01

Advanced thermal barrier coatings (TBCs) with lower thermal conductivity, increased resistance to calcium-magnesium-aluminosilicate (CMAS), and improved high-temperature capability, compared to traditional yttria-stabilized zirconia (YSZ) TBCs, are essential to higher efficiency in next generation gas turbine engines. Double-layer rare-earth zirconate/YSZ TBCs are a promising solution. From a processing perspective, solution precursor plasma spray (SPPS) process with its unique and beneficial microstructural features can be an effective approach to obtaining the double-layer microstructure. Previously durable low-thermal-conductivity YSZ TBCs with optimized layered porosity, called the inter-pass boundaries (IPBs) were produced using the SPPS process. In this study, an SPPS gadolinium zirconate (GZO) protective surface layer was successfully added. These SPPS double-layer TBCs not only retained good cyclic durability and low thermal conductivity, but also demonstrated favorable phase stability and increased surface temperature capabilities. The CMAS resistance was evaluated with both accumulative and single applications of simulated CMAS in isothermal furnaces. The double-layer YSZ/GZO exhibited dramatic improvement in the single application, but not in the continuous one. In addition, to explore their potential application in integrated gasification combined cycle environments, double-layer TBCs were tested under high-temperature humidity and encouraging performance was recorded.

Organic doping of rotated double layer graphene

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

George, Lijin; Jaiswal, Manu, E-mail: manu.jaiswal@iitm.ac.in

2016-05-06

Charge transfer techniques have been extensively used as knobs to tune electronic properties of two- dimensional systems, such as, for the modulation of conductivity \\ mobility of single layer graphene and for opening the bandgap in bilayer graphene. The charge injected into the graphene layer shifts the Fermi level away from the minimum density of states point (Dirac point). In this work, we study charge transfer in rotated double-layer graphene achieved by the use of organic dopant, Tetracyanoquinodimethane. Naturally occurring bilayer graphene has a well-defined A-B stacking whereas in rotated double-layer the two graphene layers are randomly stacked with differentmore » rotational angles. This rotation is expected to significantly alter the interlayer interaction. Double-layer samples are prepared using layer-by-layer assembly of chemical vapor deposited single-layer graphene and they are identified by characteristic resonance in the Raman spectrum. The charge transfer and distribution of charges between the two graphene layers is studied using Raman spectroscopy and the results are compared with that for single-layer and A-B stacked bilayer graphene doped under identical conditions.« less

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

Starcher, Autumn N.; Elzinga, Evert J.; Sparks, Donald L.

Previous research demonstrated the formation of single divalent metal (Co, Ni, and ZnAl) and mixed divalent metal (NiZnAl) layered double hydroxide (LDH) phases from reactions of the divalent metal with Al-bearing substrates and soils in both laboratory experiments and in the natural environment. Recently Fe(II)-Al-LDH phases have been found in laboratory batch reaction studies, and although they have yet to be found in the natural environment. Potential locations of Fe(II)-Al-LDH phases in nature include areas with suboxic and anoxic conditions. Because these areas can be environments of significant contaminant accumulation, it is important to understand the possible interactions and impactsmore » of contaminant elements on LDH phase formation. One such contaminant, Zn, can also form as an LDH and has been found to form as a mixed divalent layered hydroxide phase. To understand how Zn impacts the formation of Fe(II)-Al-LDH phase formation and kinetics, 3 mM or 0.8 mM Fe(II) and 0.8 mM Zn were batch reacted with either 10 g/L pyrophyllite or 7.5 g/L γ-Al2O3 for up to three months under anoxic conditions. Aqueous samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) and solid samples were analyzed with X-ray absorption spectroscopy (XAS). Shell-by-shell fits of Fe(II) and co-sorption samples with pyrophyllite show the formation of a mixed divalent metal (Fe(II)-Zn-Al) layered hydroxide phase, while Fe(II) and Zn co-sorption samples with γ-Al2O3 produce Fe(II)-Al-LDH phases and Zn in inner-sphere complexation with the γ-Al2O3. This study demonstrates the formation of a mixed divalent metal layered hydroxide and further iterates the importance of sorbent reactivity on LDH phase formation.« less

Electron temperature differences and double layers

NASA Technical Reports Server (NTRS)

Chan, C.; Hershkowitz, N.; Lonngren, K. E.

1983-01-01

Electron temperature differences across plasma double layers are studied experimentally. It is shown that the temperature differences across a double layer can be varied and are not a result of thermalization of the bump-on-tail distribution. The implications of these results for electron thermal energy transport in laser-pellet and tandem-mirror experiments are also discussed.

Compressive and rarefactive double layers in non-uniform plasma with q-nonextensive distributed electrons

NASA Astrophysics Data System (ADS)

Shan, S. Ali; Saleem, H.

2018-05-01

Electrostatic solitary waves and double layers (DLs) formed by the coupled ion acoustic (IA) and drift waves have been investigated in non-uniform plasma using q-nonextensive distribution function for the electrons and assuming ions to be cold Ti< Te. It is found that both compressive and rarefactive nonlinear structures (solitary waves and DLs) are possible in such a system. The steeper gradients are supportive for compressive solitary (and double layers) and destructive for rarefactive ones. The q-nonextensivity parameter q and the magnitudes of gradient scale lengths of density and temperature have significant effects on the amplitude of the double layers (and double layers) as well as on the speed of these structures. This theoretical model is general which has been applied here to the F-region ionosphere for illustration.

A fluid description of plasma double-layers

NASA Technical Reports Server (NTRS)

Levine, J. S.; Crawford, F. W.

1979-01-01

The space-charge double-layer that forms between two plasmas with different densities and thermal energies was investigated using three progressively realistic models which are treated by fluid theory, and take into account four species of particles: electrons and ions reflected by the double-layer, and electrons and ions transmitted through it. The two plasmas are assumed to be cold, and the self-consistent potential, electric field and space-charge distributions within the double-layer are determined. The effects of thermal velocities are taken into account for the reflected particles, and the modifications to the cold plasma solutions are established. Further modifications due to thermal velocities of the transmitted particles are examined. The applicability of a one dimensional fluid description, rather than plasma kinetic theory, is discussed. Theoretical predictions are compared with double layer potentials and lengths deduced from laboratory and space plasma experiments.

A new hydrodynamic analysis of double layers

NASA Technical Reports Server (NTRS)

Hora, Heinrich

1987-01-01

A genuine two-fluid model of plasmas with collisions permits the calculation of dynamic (not necessarily static) electric fields and double layers inside of plasmas including oscillations and damping. For the first time a macroscopic model for coupling of electromagnetic and Langmuir waves was achieved with realistic damping. Starting points were laser-produced plasmas showing very high dynamic electric fields in nonlinear force-produced cavitous and inverted double layers in agreement with experiments. Applications for any inhomogeneous plasma as in laboratory or in astrophysical plasmas can then be followed up by a transparent hydrodynamic description. Results are the rotation of plasmas in magnetic fields and a new second harmonic resonance, explanation of the measured inverted double layers, explanation of the observed density-independent, second harmonics emission from laser-produced plasmas, and a laser acceleration scheme by the very high fields of the double layers.

Synergetic effect of double-step blocking layer for the perovskite solar cell

NASA Astrophysics Data System (ADS)

Kim, Jinhyun; Hwang, Taehyun; Lee, Sangheon; Lee, Byungho; Kim, Jaewon; Kim, Jaewook; Gil, Bumjin; Park, Byungwoo

2017-10-01

In an organometallic CH3NH3PbI3 (MAPbI3) perovskite solar cell, we have demonstrated a vastly compact TiO2 layer synthesized by double-step deposition, through a combination of sputter and solution deposition to minimize the electron-hole recombination and boost the power conversion efficiency. As a result, the double-step strategy allowed outstanding transmittance of blocking layer. Additionally, crystallinity and morphology of the perovskite film were significantly modified, provoking enhanced photon absorption and solar cell performance with the reduced recombination rate. Thereby, this straightforward double-step strategy for the blocking layer exhibited 12.31% conversion efficiency through morphological improvements of each layer.

Effect of double layer thickness on magnetoelectric coupling in multiferroic BaTiO3-Bi0.95Gd0.05FeO3 multilayers

NASA Astrophysics Data System (ADS)

Hohenberger, S.; Lazenka, V.; Temst, K.; Selle, S.; Patzig, C.; Höche, T.; Grundmann, M.; Lorenz, M.

2018-05-01

The effect of double-layer thickness and partial substitution of Bi3+ by Gd3+ is demonstrated for multiferroic BaTiO3–BiFeO3 2–2 heterostructures. Multilayers of 15 double layers of BaTiO3 and Bi0.95Gd0.05FeO3 were deposited onto (0 0 1) oriented SrTiO3 substrates by pulsed laser deposition with various double layer thicknesses. X-ray diffraction and high resolution transmission electron microscopy investigations revealed a systematic strain tuning with layer thickness via coherently strained interfaces. The multilayers show increasingly enhanced magnetoelectric coupling with reduced double layer thickness. The maximum magnetoelectric coupling coefficient was measured to be as high as 50.8 V cm‑1 Oe‑1 in 0 T DC bias magnetic field at room temperature, and 54.9 V cm‑1 Oe‑1 above 3 T for the sample with the thinnest double layer thickness of 22.5 nm. This enhancement is accompanied by progressively increasing perpendicular magnetic anisotropy and compressive out-of-plane strain. To understand the origin of the enhanced magnetoelectric coupling in such multilayers, the temperature and magnetic field dependency of is discussed. The magnetoelectric performance of the Gd3+ substituted samples is found to be slightly enhanced when compared to unsubstituted BaTiO3–BiFeO3 multilayers of comparable double-layer thickness.

BiVO4/WO3/SnO2 Double-Heterojunction Photoanode with Enhanced Charge Separation and Visible-Transparency for Bias-Free Solar Water-Splitting with a Perovskite Solar Cell.

PubMed

Baek, Ji Hyun; Kim, Byeong Jo; Han, Gill Sang; Hwang, Sung Won; Kim, Dong Rip; Cho, In Sun; Jung, Hyun Suk

2017-01-18

Coupling dissimilar oxides in heterostructures allows the engineering of interfacial, optical, charge separation/transport and transfer properties of photoanodes for photoelectrochemical (PEC) water splitting. Here, we demonstrate a double-heterojunction concept based on a BiVO 4 /WO 3 /SnO 2 triple-layer planar heterojunction (TPH) photoanode, which shows simultaneous improvements in the charge transport (∼93% at 1.23 V vs RHE) and transmittance at longer wavelengths (>500 nm). The TPH photoanode was prepared by a facile solution method: a porous SnO 2 film was first deposited on a fluorine-doped tin oxide (FTO)/glass substrate followed by WO 3 deposition, leading to the formation of a double layer of dense WO 3 and a WO 3 /SnO 2 mixture at the bottom. Subsequently, a BiVO 4 nanoparticle film was deposited by spin coating. Importantly, the WO 3 /(WO 3 +SnO 2 ) composite bottom layer forms a disordered heterojunction, enabling intimate contact, lower interfacial resistance, and efficient charge transport/transfer. In addition, the top BiVO 4 /WO 3 heterojunction layer improves light absorption and charge separation. The resultant TPH photoanode shows greatly improved internal quantum efficiency (∼80%) and PEC water oxidation performance (∼3.1 mA/cm 2 at 1.23 V vs RHE) compared to the previously reported BiVO 4 /WO 3 photoanodes. The PEC performance was further improved by a reactive-ion etching treatment and CoO x electrocatalyst deposition. Finally, we demonstrated a bias-free and stable solar water-splitting by constructing a tandem PEC device with a perovskite solar cell (STH ∼3.5%).

New physiologically-relevant liver tissue model based on hierarchically cocultured primary rat hepatocytes with liver endothelial cells.

PubMed

Xiao, Wenjin; Perry, Guillaume; Komori, Kikuo; Sakai, Yasuyuki

2015-11-01

To develop an in vitro liver tissue equivalent, hepatocytes should be cocultured with liver non-parenchymal cells to mimic the in vivo physiological microenvironments. In this work, we describe a physiologically-relevant liver tissue model by hierarchically organizing layers of primary rat hepatocytes and human liver sinusoidal endothelial cells (TMNK-1) on an oxygen-permeable polydimethylsiloxane (PDMS) membrane, which facilitates direct oxygenation by diffusion through the membrane. This in vivo-mimicking hierarchical coculture was obtained by simply proceeding the overlay of TMNK-1 cells on the hepatocyte layer re-formed on the collagen immobilized PDMS membranes. The comparison of hepatic functionalities was achieved between coculture and sandwich culture with Matrigel, in the presence and absence of direct oxygenation. A complete double-layered structure of functional liver cells with vertical contact between hepatocytes and TMNK-1 was successfully constructed in the coculture with direct oxygen supply and was well-maintained for 14 days. The hepatocytes in this hierarchical culture exhibited improved survival, functional bile canaliculi formation, cellular level polarization and maintenance of metabolic activities including Cyp1A1/2 activity and albumin production. By contrast, the two cell populations formed discontinuous monolayers on the same surfaces in the non-oxygen-permeable cultures. These results demonstrate that (i) the direct oxygenation through the PDMS membranes enables very simple formation of a hierarchical structure consisting of a hepatocyte layer and a layer of TMNK-1 and (ii) we may include other non-parenchymal cells in this format easily, which can be widely applicable to other epithelial organs.

Effective self-purification of polynary metal electroplating wastewaters through formation of layered double hydroxides.

PubMed

Zhou, Ji Zhi; Wu, Yue Ying; Liu, Chong; Orpe, Ajay; Liu, Qiang; Xu, Zhi Ping; Qian, Guang Ren; Qiao, Shi Zhang

2010-12-01

Heavy metal ions (Ni(2+), Zn(2+), and Cr(3+)) can be effectively removed from real polynary metal ions-bearing electroplating wastewaters by a carbonation process, with ∼99% of metal ions removed in most cases. The synchronous formation of layered double hydroxide (LDH) precipitates containing these metal ions was responsible for the self-purification of wastewaters. The constituents of formed polynary metals-LDHs mainly depended on the Ni(2+):Zn(2+):Cr(3+) molar ratio in wastewaters. LDH was formed at pH of 6.0-8.0 when the Ni(2+)/Zn(2+) molar ratio ≥ 1 where molar fraction of trivalent metal in the wastewaters was 0.2-0.4, otherwise ZnO, hydrozincite, or amorphous precipitate was observed. In the case of LDH formation, the residual concentration of Ni(2+), Zn(2+), and Cr(3+) in the treated wastewaters was very low, about 2-3, ∼2, and ∼1 mg/L, respectively, at 20-80 °C and pH of 6.0-8.0, indicating the effective incorporation of heavy metal ions into the LDH matrix. Furthermore, the obtained LDH materials were used to adsorb azoic dye GR, with the maximum adsorption amount of 129-134 mg/g. We also found that the obtained LDHs catalyzed more than 65% toluene to decompose at 350 °C under ambient pressure. Thus the current research has not only shown effective recovery of heavy metal ions from the electroplating wastewaters in an environmentally friendly process but also demonstrated the potential utilization of recovered materials.

Formation of crystalline Zn-Al layered double hydroxide precipitates on γ-alumina: the role of mineral dissolution.

PubMed

Li, Wei; Livi, Kenneth J T; Xu, Wenqian; Siebecker, Matthew G; Wang, Yujun; Phillips, Brian L; Sparks, Donald L

2012-11-06

To better understand the sequestration of toxic metals such as nickel (Ni), zinc (Zn), and cobalt (Co) as layered double hydroxide (LDH) phases in soils, we systematically examined the presence of Al and the role of mineral dissolution during Zn sorption/precipitation on γ-Al(2)O(3) (γ-alumina) at pH 7.5 using extended X-ray absorption fine structure spectroscopy (EXAFS), high-resolution transmission electron microscopy (HR-TEM), synchrotron-radiation powder X-ray diffraction (SR-XRD), and (27)Al solid-state NMR. The EXAFS analysis indicates the formation of Zn-Al LDH precipitates at Zn concentration ≥0.4 mM, and both HR-TEM and SR-XRD reveal that these precipitates are crystalline. These precipitates yield a small shoulder at δ(Al-27) = +12.5 ppm in the (27)Al solid-state NMR spectra, consistent with the mixed octahedral Al/Zn chemical environment in typical Zn-Al LDHs. The NMR analysis provides direct evidence for the existence of Al in the precipitates and the migration from the dissolution of γ-alumina substrate. To further address this issue, we compared the Zn sorption mechanism on a series of Al (hydr)oxides with similar chemical composition but differing dissolubility using EXAFS and TEM. These results suggest that, under the same experimental conditions, Zn-Al LDH precipitates formed on γ-alumina and corundum but not on less soluble minerals such as bayerite, boehmite, and gibbsite, which point outs that substrate mineral surface dissolution plays an important role in the formation of Zn-Al LDH precipitates.

Unravelling the electrochemical double layer by direct probing of the solid/liquid interface

PubMed Central

Favaro, Marco; Jeong, Beomgyun; Ross, Philip N.; Yano, Junko; Hussain, Zahid; Liu, Zhi; Crumlin, Ethan J.

2016-01-01

The electrochemical double layer plays a critical role in electrochemical processes. Whilst there have been many theoretical models predicting structural and electrical organization of the electrochemical double layer, the experimental verification of these models has been challenging due to the limitations of available experimental techniques. The induced potential drop in the electrolyte has never been directly observed and verified experimentally, to the best of our knowledge. In this study, we report the direct probing of the potential drop as well as the potential of zero charge by means of ambient pressure X-ray photoelectron spectroscopy performed under polarization conditions. By analyzing the spectra of the solvent (water) and a spectator neutral molecule with numerical simulations of the electric field, we discern the shape of the electrochemical double layer profile. In addition, we determine how the electrochemical double layer changes as a function of both the electrolyte concentration and applied potential. PMID:27576762

Sub-Grid Modeling of Electrokinetic Effects in Micro Flows

NASA Technical Reports Server (NTRS)

Chen, C. P.

2005-01-01

Advances in micro-fabrication processes have generated tremendous interests in miniaturizing chemical and biomedical analyses into integrated microsystems (Lab-on-Chip devices). To successfully design and operate the micro fluidics system, it is essential to understand the fundamental fluid flow phenomena when channel sizes are shrink to micron or even nano dimensions. One important phenomenon is the electro kinetic effect in micro/nano channels due to the existence of the electrical double layer (EDL) near a solid-liquid interface. Not only EDL is responsible for electro-osmosis pumping when an electric field parallel to the surface is imposed, EDL also causes extra flow resistance (the electro-viscous effect) and flow anomaly (such as early transition from laminar to turbulent flow) observed in pressure-driven microchannel flows. Modeling and simulation of electro-kinetic effects on micro flows poses significant numerical challenge due to the fact that the sizes of the double layer (10 nm up to microns) are very thin compared to channel width (can be up to 100 s of m). Since the typical thickness of the double layer is extremely small compared to the channel width, it would be computationally very costly to capture the velocity profile inside the double layer by placing sufficient number of grid cells in the layer to resolve the velocity changes, especially in complex, 3-d geometries. Existing approaches using "slip" wall velocity and augmented double layer are difficult to use when the flow geometry is complicated, e.g. flow in a T-junction, X-junction, etc. In order to overcome the difficulties arising from those two approaches, we have developed a sub-grid integration method to properly account for the physics of the double layer. The integration approach can be used on simple or complicated flow geometries. Resolution of the double layer is not needed in this approach, and the effects of the double layer can be accounted for at the same time. With this approach, the numeric grid size can be much larger than the thickness of double layer. Presented in this report are a description of the approach, methodology for implementation and several validation simulations for micro flows.

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

Fayolle, M.; Yamaguchi, M.; Ohto, T.

Organic magnetoresistance (OMAR) can be caused by either single carrier (bipolaron) or double carriers (electron-hole)-based mechanisms. In order to consider applications for OMAR, it is important to control the mechanism present in the device. In this paper, we report the effect of traps on OMAR resulting of disorder at the interface between the organic active layer with the hole injection layer [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate): PEDOT:PSS]. It has been found that while the single carriers OMAR is enhanced by the presence of traps, the double carriers OMAR is totally removed in a sample with a high interface trap density. The reasons formore » these results are discussed based on the impedance spectroscopy measurements. First, the mechanism (single or double carriers) responsible of the OMAR was determined with the support of the capacitance measurement. Then, the influence of traps was discussed with the Nyquist diagrams and phase angle-frequency plots of the samples. The results suggested that with a rough interface and thus high disorder, the presence of traps enhanced the bipolaron formation. Traps also acted as recombination centers for electron-hole pairs, which prevented the double carriers OMAR in devices with a rough interface. On the other hand, with a low trap density, i.e., with a smooth surface, the single carrier OMAR decreased, and double carriers OMAR appeared. The sign of the OMAR could then be controlled by simply sweeping the bias voltage. This work demonstrated that the roughness at the interface is important for controlling OMAR and its reproducibility, and that the combination of OMAR measurement and impedance spectroscopy is helpful for clarifying the processes at the interface.« less

Exploration and exploitation of homologous series of bis(acrylamido)alkanes containing pyridyl and phenyl groups: β-sheet versus two-dimensional layers in solid-state photochemical [2 + 2] reactions.

PubMed

Garai, Mousumi; Biradha, Kumar

2015-09-01

The homologous series of phenyl and pyridyl substituted bis(acrylamido)alkanes have been synthesized with the aim of systematic analysis of their crystal structures and their solid-state [2 + 2] reactivities. The changes in the crystal structures with respect to a small change in the molecular structure, that is by varying alkyl spacers between acrylamides and/or by varying the end groups (phenyl, 2-pyridyl, 3-pyridyl, 4-pyridyl) on the C-terminal of the amide, were analyzed in terms of hydrogen-bonding interference (N-H⋯Npy versus N-H⋯O=C) and network geometries. In this series, a greater tendency towards the formation of N-H⋯O hydrogen bonds (β-sheets and two-dimensional networks) over N-H⋯N hydrogen bonds was observed. Among all the structures seven structures were found to have the required alignments of double bonds for the [2 + 2] reaction such that the formations of single dimer, double dimer and polymer are facilitated. However, only four structures were found to exhibit such a solid-state [2 + 2] reaction to form a single dimer and polymers. The two-dimensional hydrogen-bonding layer via N-H⋯O hydrogen bonds was found to promote solid-state [2 + 2] photo-polymerization in a single-crystal-to-single-crystal manner. Such two-dimensional layers were encountered only when the spacer between acryl amide moieties is butyl. Only four out of the 16 derivatives were found to form hydrates, two each from 2-pyridyl and 4-pyridyl derivatives. The water molecules in these structures govern the hydrogen-bonding networks by the formation of an octameric water cluster and one-dimensional zigzag water chains. The trends in the melting points and densities were also analyzed.

Pd/Ni-WO3 anodic double layer gasochromic device

DOEpatents

Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland; Liu, Ping

2004-04-20

An anodic double layer gasochromic sensor structure for optical detection of hydrogen in improved response time and with improved optical absorption real time constants, comprising: a glass substrate; a tungsten-doped nickel oxide layer coated on the glass substrate; and a palladium layer coated on the tungsten-doped nickel oxide layer.

Topological defects in electric double layers of ionic liquids at carbon interfaces

DOE PAGES

Black, Jennifer M.; Okatan, Mahmut Baris; Feng, Guang; ...

2015-06-07

The structure and properties of the electrical double layer in ionic liquids is of interest in a wide range of areas including energy storage, catalysis, lubrication, and many more. Theories describing the electrical double layer for ionic liquids have been proposed, however a full molecular level description of the double layer is lacking. To date, studies have been predominantly focused on ion distributions normal to the surface, however the 3D nature of the electrical double layer in ionic liquids requires a full picture of the double layer structure not only normal to the surface, but also in plane. Here wemore » utilize 3D force mapping to probe the in plane structure of an ionic liquid at a graphite interface and report the direct observation of the structure and properties of topological defects. The observation of ion layering at structural defects such as step-edges, reinforced by molecular dynamics simulations, defines the spatial resolution of the method. Observation of defects allows for the establishment of the universality of ionic liquid behavior vs. separation from the carbon surface and to map internal defect structure. In conclusion, these studies offer a universal pathway for probing the internal structure of topological defects in soft condensed matter on the nanometer level in three dimensions.« less

Double-diffusive convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability

NASA Astrophysics Data System (ADS)

Vincze, Miklos; Borcia, Ion; Harlander, Uwe; Le Gal, Patrice

2016-12-01

A water-filled differentially heated rotating annulus with initially prepared stable vertical salinity profiles is studied in the laboratory. Based on two-dimensional horizontal particle image velocimetry data and infrared camera visualizations, we describe the appearance and the characteristics of the baroclinic instability in this original configuration. First, we show that when the salinity profile is linear and confined between two non-stratified layers at top and bottom, only two separate shallow fluid layers can be destabilized. These unstable layers appear nearby the top and the bottom of the tank with a stratified motionless zone between them. This laboratory arrangement is thus particularly interesting to model geophysical or astrophysical situations where stratified regions are often juxtaposed to convective ones. Then, for more general but stable initial density profiles, statistical measures are introduced to quantify the extent of the baroclinic instability at given depths and to analyze the connections between this depth-dependence and the vertical salinity profiles. We find that, although the presence of stable stratification generally hinders full-depth overturning, double-diffusive convection can lead to development of multicellular sideways convection in shallow layers and subsequently to a multilayered baroclinic instability. Therefore we conclude that by decreasing the characteristic vertical scale of the flow, stratification may even enhance the formation of cyclonic and anticyclonic eddies (and thus, mixing) in a local sense.

Accretion onto neutron stars with the presence of a double layer

NASA Technical Reports Server (NTRS)

Williams, A. C.; Weisskopf, M. C.; Elsner, R. F.; Darbro, W.; Sutherland, P. G.

1986-01-01

It is known from laboratory experiments that double layers can form in plasmas, usually in the presence of an electric current. It is argued that a double layer may be present in the accretion column of a neutron star in a binary system. It is suggested that the double layer may be the predominant deceleration mechanism for the accreting ions, especially for sources with X-ray luminosities of less than about 10 to the 37th erg/s. Previous models have involved either a collisionless shock or an assumed gradual deceleration of the accreting ions to thermalize the energy of the infalling matter.

Accretion onto neutron stars with the presence of a double layer

NASA Technical Reports Server (NTRS)

Williams, A. C.; Weisskopf, M. C.; Elsner, R. F.; Darbro, W.; Sutherland, P. G.

1987-01-01

It is known, from laboratory experiments, that double layers will form in plasmas, usually in the presence of an electric current. It is argued that a double layer may be present in the accretion column of a neutron star in a binary system. It is suggested that the double layer may be the predominant deceleration mechanism for the accreting ions, especially for sources with X-ray luminosities of less than about 10 to the 37th erg/s. Previous models have involved either a collisionless shock or an assumed gradual deceleration of the accreting ions to thermalize the energy of the infalling matter.

Challenges facing lithium batteries and electrical double-layer capacitors.

PubMed

Choi, Nam-Soon; Chen, Zonghai; Freunberger, Stefan A; Ji, Xiulei; Sun, Yang-Kook; Amine, Khalil; Yushin, Gleb; Nazar, Linda F; Cho, Jaephil; Bruce, Peter G

2012-10-01

Energy-storage technologies, including electrical double-layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and "load leveling" of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double-layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double-layer capacitors. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Colloidal models. A bit of history.

PubMed

Lyklema, Johannes

2015-05-15

This paper offers an anthology on developments in colloid and interface science emphasizing themes that may be of direct or indirect interest to Interfaces Against Pollution. Topics include the determination of Avogadro's number, development in the insight into driving forces for double layer formation, colloid stability, thin films, and thermodynamic approaches in interfacial electrochemistry. Some personal reminiscences of key players in the field are included, partly to illustrate historical developments. Copyright © 2014 Elsevier Inc. All rights reserved.

Dielectric-spectroscopy approach to ferrofluid nanoparticle clustering induced by an external electric field.

PubMed

Rajnak, Michal; Kurimsky, Juraj; Dolnik, Bystrik; Kopcansky, Peter; Tomasovicova, Natalia; Taculescu-Moaca, Elena Alina; Timko, Milan

2014-09-01

An experimental study of magnetic colloidal particles cluster formation induced by an external electric field in a ferrofluid based on transformer oil is presented. Using frequency domain isothermal dielectric spectroscopy, we study the influence of a test cell electrode separation distance on a low-frequency relaxation process. We consider the relaxation process to be associated with an electric double layer polarization taking place on the particle surface. It has been found that the relaxation maximum considerably shifts towards lower frequencies when conducting the measurements in the test cells with greater electrode separation distances. As the electric field intensity was always kept at a constant value, we propose that the particle cluster formation induced by the external ac electric field accounts for that phenomenon. The increase in the relaxation time is in accordance with the Schwarz theory of electric double layer polarization. In addition, we analyze the influence of a static electric field generated by dc bias voltage on a similar shift in the relaxation maximum position. The variation of the dc electric field for the hysteresis measurements purpose provides understanding of the development of the particle clusters and their decay. Following our results, we emphasize the utility of dielectric spectroscopy as a simple, complementary method for detection and study of clusters of colloidal particles induced by external electric field.

Runx2 is required for early stages of endochondral bone formation but delays final stages of bone repair in Axin2-deficient mice

PubMed Central

McGee-Lawrence, Meghan E.; Carpio, Lomeli R.; Bradley, Elizabeth W.; Dudakovic, Amel; Lian, Jane B.; van Wijnen, Andre J.; Kakar, Sanjeev; Hsu, Wei; Westendorf, Jennifer J.

2014-01-01

Runx2 and Axin2 regulate skeletal development. We recently determined that Axin2 and Runx2 molecularly interact in differentiating osteoblasts to regulate intramembranous bone formation, but the relationship between these factors in endochondral bone formation was unresolved. To address this, we examined the effects of Axin2 deficiency on the cleidocranial dysplasia (CCD) phenotype of Runx2+/− mice, focusing on skeletal defects attributed to improper endochondral bone formation. Axin2 deficiency unexpectedly exacerbated calvarial components of the CCD phenotype in the Runx2+/− mice; the endocranial layer of the frontal suture, which develops by endochondral bone formation, failed to mineralize in the Axin2−/−:Runx2+/− mice, resulting in a cartilaginous, fibrotic and larger fontanel than observed in Runx2+/− mice. Transcripts associated with cartilage development (e.g., Acan, miR140) were expressed at higher levels, whereas blood vessel morphogenesis transcripts (e.g., Slit2) were suppressed in Axin2−/−:Runx2+/− calvaria. Cartilage maturation was impaired, as primary chondrocytes from double mutant mice demonstrated delayed differentiation and produced less calcified matrix in vitro. The genetic dominance of Runx2 was also reflected during endochondral fracture repair, as both Runx2+/− and double mutant Axin2−/−:Runx2+/− mice had enlarged fracture calluses at early stages of healing. However, by the end stages of fracture healing, double mutant animals diverged from the Runx2+/− mice, showing smaller calluses and increased torsional strength indicative of more rapid end stage bone formation as seen in the Axin2−/− mice. Taken together, our data demonstrate a dominant role for Runx2 in chondrocyte maturation, but implicate Axin2 as an important modulator of the terminal stages of endochondral bone formation. PMID:24973690

Self-Organized Mantle Layering After the Magma-Ocean Period

NASA Astrophysics Data System (ADS)

Hansen, U.; Dude, S.

2017-12-01

The thermal history of the Earth, it's chemical differentiation and also the reaction of the interior with the atmosphere is largely determined by convective processes within the Earth's mantle. A simple physical model, resembling the situation, shortly after core formation, consists of a compositionally stable stratified mantle, as resulting from fractional crystallization of the magma ocean. The early mantle is subject to heating from below by the Earth's core and cooling from the top through the atmosphere. Additionally internal heat sources will serve to power the mantle dynamics. Under such circumstances double diffusive convection will eventually lead to self -organized layer formation, even without the preexisting jumps is material properties. We have conducted 2D and 3D numerical experiments in Cartesian and spherical geometry, taking into account mantle realistic values, especially a strong temperature dependent viscosity and a pressure dependent thermal expansivity . The experiments show that in a wide parameter range. distinct convective layers evolve in this scenario. The layering strongly controls the heat loss from the core and decouples the dynamics in the lower mantle from the upper part. With time, individual layers grow on the expense of others and merging of layers does occur. We observe several events of intermittent breakdown of individual layers. Altogether an evolution emerges, characterized by continuous but also spontaneous changes in the mantle structure, ranging from multiple to single layer flow. Such an evolutionary path of mantle convection allows to interpret phenomena ranging from stagnation of slabs at various depth to variations in the chemical signature of mantle upwellings in a new framework.

Double Negative Materials (DNM), Phenomena and Applications

DTIC Science & Technology

2009-07-01

Nanoparticles Formed by Pairs Of Concentric Double-Negative (DNG), Single-Negative ( SNG ) and/or Double-Positive (DPS) Metamaterial Layers.” J. Appl...material RRL Rapid Research Letters SHG second-harmonic generation SNG single-negative SSR split-ring resonator A-1 Appendix A. October 2008...Pairs of Concentric Double-Negative (DNG), Single-Negative ( SNG ), and/or Double-Positive (DPS) Metamaterial Layers.” J. Appl. Phys. 97, no. 9 (May

Meissner effect in normal-superconducting proximity-contact double layers

NASA Astrophysics Data System (ADS)

Higashitani, Seiji; Nagai, Katsuhiko

1995-02-01

The Meissner effect in normal-superconducting proximity-contact double layers is discussed in the clean limit. The diamagnetic current is calculated using the quasi-classical Green's function. We obtain the quasi-classical Green's function linear in the vector potential in the proximity-contact double layers with a finite reflection coefficient at the interface. It is found that the diamagnetic current in the clean normal layer is constant in space, therefore, the magnetic field linearly decreases in the clean normal layer. We give an explicit expression for the screening length in the clean normal layer and study its temperature dependence. We show that the temperature dependence in the clean normal layer is considerably different from that in the dirty normal layer and agrees with a recent experiment in Au-Nb system.

Surface plasmon dispersion engineering via double-metallic AU/AG layers for nitride light-emitting diodes

DOEpatents

Tansu, Nelson; Zhao, Hongping; Zhang, Jing; Liu, Guangyu

2014-04-01

A double-metallic deposition process is used whereby adjacent layers of different metals are deposited on a substrate. The surface plasmon frequency of a base layer of a first metal is tuned by the surface plasmon frequency of a second layer of a second metal formed thereon. The amount of tuning is dependent upon the thickness of the metallic layers, and thus tuning can be achieved by varying the thicknesses of one or both of the metallic layers. In a preferred embodiment directed to enhanced LED technology in the green spectrum regime, a double-metallic Au/Ag layer comprising a base layer of gold (Au) followed by a second layer of silver (Ag) formed thereon is deposited on top of InGaN/GaN quantum wells (QWs) on a sapphire/GaN substrate.

The scaling of relativistic double-year widths - Poisson-Vlasov solutions and particle-in-cell simulations

NASA Technical Reports Server (NTRS)

Sulkanen, Martin E.; Borovsky, Joseph E.

1992-01-01

The study of relativistic plasma double layers is described through the solution of the one-dimensional, unmagnetized, steady-state Poisson-Vlasov equations and by means of one-dimensional, unmagnetized, particle-in-cell simulations. The thickness vs potential-drop scaling law is extended to relativistic potential drops and relativistic plasma temperatures. The transition in the scaling law for 'strong' double layers suggested by analytical two-beam models by Carlqvist (1982) is confirmed, and causality problems of standard double-layer simulation techniques applied to relativistic plasma systems are discussed.

Suppressing longitudinal double-layer oscillations by using elliptically polarized laser pulses in the hole-boring radiation pressure acceleration regime

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

Wu Dong; Yan, X. Q.; Key Laboratory of High Energy Density Physics Simulation, Ministry of Education, Peking University, Beijing 100871

It is shown that well collimated mono-energetic ion beams with a large particle number can be generated in the hole-boring radiation pressure acceleration regime by using an elliptically polarized laser pulse with appropriate theoretically determined laser polarization ratio. Due to the J Multiplication-Sign B effect, the double-layer charge separation region is imbued with hot electrons that prevent ion pileup, thus suppressing the double-layer oscillations. The proposed mechanism is well confirmed by Particle-in-Cell simulations, and after suppressing the longitudinal double-layer oscillations, the ion beams driven by the elliptically polarized lasers own much better energy spectrum than those by circularly polarized lasers.

Unravelling the electrochemical double layer by direct probing of the solid/liquid interface

DOE PAGES

Favaro, Marco; Jeong, Beomgyun; Ross, Philip N.; ...

2016-08-31

The electrochemical double layer plays a critical role in electrochemical processes. Whilst there have been many theoretical models predicting structural and electrical organization of the electrochemical double layer, the experimental verification of these models has been challenging due to the limitations of available experimental techniques. The induced potential drop in the electrolyte has never been directly observed and verified experimentally, to the best of our knowledge. In this study, we report the direct probing of the potential drop as well as the potential of zero charge by means of ambient pressure X-ray photoelectron spectroscopy performed under polarization conditions. By analyzingmore » the spectra of the solvent (water) and a spectator neutral molecule with numerical simulations of the electric field, we discern the shape of the electrochemical double layer profile. In addition, we determine how the electrochemical double layer changes as a function of both the electrolyte concentration and applied potential.« less

Carbon Textile Decorated with Pseudocapacitive VC/Vx Oy for High-Performance Flexible Supercapacitors.

PubMed

Van Lam, Do; Shim, Hyung Cheoul; Kim, Jae-Hyun; Lee, Hak-Joo; Lee, Seung-Mo

2017-11-01

It is demonstrated that, via V 2 O 5 coating by low temperature atomic layer deposition and subsequent pyrolysis, ubiquitous cotton textile can readily turn into high-surface-area carbon textile fully decorated with pseudocapacitive V x O y /VC widely usable as electrodes of high-performance supercapacitor. It is found that carbothermic reduction of V 2 O 5 (C + V 2 O 5 → C' + VC + CO/CO 2 (g)) leads to chemical/mechanical activation of carbon textile, thereby producing high-surface-area conductive carbon textile. In addition, sequential phase transformation and carbide formation (V 2 O 5 → V x O y → VC) occurred by carbothermic reduction trigger decoration of the carbon textile with redox-active V x O y /VC. Thanks to the synergistic effect of electrical double layer and pseudocapacitance, the supercapacitors made of the hybrid carbon textile exhibit far better energy density (over 30-fold increase) with excellent cycling stability than the carbon textile simply undergone pyrolysis. The method can open up a promising and facile way to synthesize hybrid electrode materials for electrochemical energy storages possessing advantages of both electrical double layer and pseudocapacitive material. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of electrical double-layer interaction on coal flotation.

PubMed

Harvey, Paul A; Nguyen, Anh V; Evans, Geoffrey M

2002-06-15

In the early 1930s it was first reported that inorganic electrolytes enhance the floatability of coal and naturally hydrophobic minerals. To date, explanations of coal flotation in electrolytes have not been entirely clear. This research investigated the floatability of coal in NaCl and MgCl2 solutions using a modified Hallimond tube to examine the role of the electrical double-layer interaction between bubbles and particles. Flotation of coal was highly dependent on changes in solution pH, type of electrolyte, and electrolyte concentration. Floatability of coal in electrolyte solutions was seen not to be entirely controlled by the electrical double-layer interaction. Coal flotation in low electrolyte concentration solutions decreases with increase in concentration, not expected from the theory since the electrical double layer is compressed, resulting in diminishing the (electrical double layer) repulsion between the bubble and the coal particles. Unlike in low electrolyte concentration solutions, coal flotation in high electrolyte concentration solutions increases with increase in electrolyte concentration. Again, this behavior of coal flotation in high electrolyte concentration solutions cannot be quantitatively explained using the electrical double-layer interaction. Possible mechanisms are discussed in terms of the bubston (i.e., bubble stabilized by ions) phenomenon, which explains the existence of the submicron gas bubbles on the hydrophobic coal surface.

Megavolt parallel potentials arising from double-layer streams in the Earth's outer radiation belt.

PubMed

Mozer, F S; Bale, S D; Bonnell, J W; Chaston, C C; Roth, I; Wygant, J

2013-12-06

Huge numbers of double layers carrying electric fields parallel to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth's outer radiation belt. For one case with adequate high time resolution data, 7000 double layers were observed in an interval of 1 min to produce a 230,000 V net parallel potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1,000,000 volts of net parallel potential crossed the spacecraft during this time. A double layer traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, the instantaneous parallel potential along a single magnetic field line was the order of tens of kilovolts. Electrons on the field line might experience many such potential steps in their lifetimes to accelerate them to energies where they serve as the seed population for relativistic acceleration by coherent, large amplitude whistler mode waves. Because the double-layer speed of 3100  km/s is the order of the electron acoustic speed (and not the ion acoustic speed) of a 25 eV plasma, the double layers may result from a new electron acoustic mode. Acceleration mechanisms involving double layers may also be important in planetary radiation belts such as Jupiter, Saturn, Uranus, and Neptune, in the solar corona during flares, and in astrophysical objects.

Transient electroosmotic flow induced by DC or AC electric fields in a curved microtube.

PubMed

Luo, W-J

2004-10-15

This study investigates transient electroosmotic flow in a rectangular curved microtube in which the fluid is driven by the application of an external DC or AC electric field. The resultant flow-field evolutions within the microtube are simulated using the backwards-Euler time-stepping numerical method to clarify the relationship between the changes in the axial-flow velocity and the intensity of the applied electric field. When the electric field is initially applied or varies, the fluid within the double layer responds virtually immediately, and the axial velocity within the double layer tends to follow the varying intensity of the applied electric field. The greatest net charge density exists at the corners of the microtube as a result of the overlapping electrical double layers of the two walls. It results in local maximum or minimum axial velocities in the corners during increasing or decreasing applied electric field intensity in either the positive or negative direction. As the fluid within the double layer starts to move, the bulk fluid is gradually dragged into motion through the diffusion of momentum from the double layer. A finite time is required for the full momentum of the double layer to diffuse to the bulk fluid; hence, a certain phase shift between the applied electric field and the flow response is inevitable. The patterns of the axial velocity contours during the transient evolution are investigated in this study. It is found that these patterns are determined by the efficiency of momentum diffusion from the double layer to the central region of the microtube.

Broadband Pillbox Antennas.

DTIC Science & Technology

1984-09-21

Identify by block number) - FIELD GROUP SUB-GROUP Double layer pillbox antennas Triple layer pillbox antenna The possibility of designing very broadband... Design .................... 1 Broadband Feed De gn ........................................... 2 Ex mental Simulation of Double Layer Pillbox...5 REFERENCES ................................................... 6 APPENDIX - COAXIAL TO WAVEGUIDE JUNCTION DESIGN

A Comparison of Solvent Effects in the Kinetics of Simple Electron Transfer and Amalgam Formation Reactions

DTIC Science & Technology

1988-10-15

by measuring the temperature dependence of the half-wave potential in a non-isothermal cell. In the case of reduction of p- semiquinones55 and p... electrooxidation of 1,4-diaminobenzene at platinum5 , it was argued that since 16 the reaction occurs close to the p.z.c., double layer effects are negligible...effects would lead to large errors in the apparent transfer coefficient, ou. In the case of kinetic data for the electrooxidation of phenothiazine 4 and

Numerically simulated two-dimensional auroral double layers

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1983-01-01

A magnetized 2 1/2-dimensional particle-in-cell system which is periodic in one direction and bounded by reservoirs of Maxwellian plasma in the other is used to numerically simulate electrostatic plasma double layers. For the cases of both oblique and two-dimensional double layers, the present results indicate periodic instability, Debye length rather than gyroradii scaling, and low frequency electrostatic turbulence together with electron beam-excited electrostatatic electron-cyclotron waves. Estimates are given for the thickness of auroral doule layers, as well as the separations within multiple auroral arcs. Attention is given to the temporal modulation of accelerated beams, and the possibilities for ion precipitation and ion conic production by the double layer are hypothesized. Simulations which include the atmospheric backscattering of electrons imply the action of an ionospheric sheath which accelerates ionospheric ions upward.

The use of dissolvable layered double hydroxide components in an in situ solid-phase extraction for chromatographic determination of tetracyclines in water and milk samples.

PubMed

Phiroonsoontorn, Nattaphorn; Sansuk, Sira; Santaladchaiyakit, Yanawath; Srijaranai, Supalax

2017-10-13

This research presents a simple and green in situ solid phase extraction (is-SPE) combined with high-performance liquid chromatography (HPLC) for the simultaneous analysis of tetracyclines (TCs) including tetracycline, oxytetracycline, and chlortetracycline. In is-SPE, TCs were efficiently extracted through the precipitation formation of dissolvable layered double hydroxides (LDHs) by mixing the LDH components such as magnesium and aluminum ions (both in metal chloride salts) thoroughly in an alkaline sample solution. After the centrifugation, the precipitate was completely dissolved with trifluoroacetic acid to release the enriched TCs, and then analyzed by HPLC. Under optimized conditions, this method gave good enrichment factors (EFs) of 41-93 with low limits of detection (LODs) of 0.7-6μg/L and limits of quantitation (LOQs) of 3-15μg/L. Also, the proposed method was successfully applied for the determination of TCs in water and milk samples with the recoveries ranging from 81.7-108.1% for water and 55.7-88.7% for milk. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of the chloride ion as a hole scavenger on the photocatalytic conversion of CO2 in an aqueous solution over Ni-Al layered double hydroxides.

PubMed

Iguchi, Shoji; Teramura, Kentaro; Hosokawa, Saburo; Tanaka, Tsunehiro

2015-07-21

The photocatalytic conversion of CO2 into useful chemical compounds in water without using organic sacrificial reagents is a promising method to overcome environmental and energy problems. Various synthesized layered double hydroxides (LDHs) are capable of reducing CO2 to CO in an aqueous solution under UV light irradiation. However, it is difficult to oxidize H2O to O2 in a photocatalytic system using LDHs as photocatalysts. In this study, we investigated the photocatalytic conversion of CO2 using a Ni-Al LDH in an aqueous solution of NaCl. Hypochlorous acid (HClO) was produced as an oxidation product of Cl(-) with the formation of reduction products such as CO and H2 under photoirradiation. We propose the inclusion of Cl(-) in the reaction solution to be one of the most promising ways for obtaining a hole scavenger, an approach that would enable the construction of an artificial photosynthesis system for the conversion of CO2.

Electrochemical characteristics of discrete, uniform, and monodispersed hollow mesoporous carbon spheres in double-layered supercapacitors.

PubMed

Chen, Xuecheng; Kierzek, Krzysztof; Wenelska, Karolina; Cendrowski, Krzystof; Gong, Jiang; Wen, Xin; Tang, Tao; Chu, Paul K; Mijowska, Ewa

2013-11-01

Core-shell-structured mesoporous silica spheres were prepared by using n-octadecyltrimethoxysilane (C18TMS) as the surfactant. Hollow mesoporous carbon spheres with controllable diameters were fabricated from core-shell-structured mesoporous silica sphere templates by chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres (HCSs) with different diameters can be obtained. The use of ethylene as the carbon precursor in the CVD process produces the materials in a single step without the need to remove the surfactant. The mechanism of formation and the role played by the surfactant, C18TMS, are investigated. The materials have large potential in double-layer supercapacitors, and their electrochemical properties were determined. HCSs with thicker mesoporous shells possess a larger surface area, which in turn increases their electrochemical capacitance. The samples prepared at a lower temperature also exhibit increased capacitance as a result of the Brunauer-Emmett-Teller (BET) area and larger pore size. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of surface chemical properties of activated carbon modified by amino-fluorination for electric double-layer capacitor.

PubMed

Jung, Min-Jung; Jeong, Euigyung; Cho, Seho; Yeo, Sang Young; Lee, Young-Seak

2012-09-01

The surface of phenol-based activated carbon (AC) was seriatim amino-fluorinated with solution of ammonium hydroxide and hydrofluoric acid in varying ratio to fabricate electrode materials for use in an electric double-layer capacitor (EDLC). The specific capacitance of the amino-fluorinated AC-based EDLC was measured in a 1 M H(2)SO(4) electrolyte, in which it was observed that the specific capacitances increased from 215 to 389 Fg(-1) and 119 and 250 Fg(-1) with the current densities of 0.1 and 1.0 Ag(-1), respectively, in comparison with those of an untreated AC-based EDLC when the amino-fluorination was optimized via seriatim mixed solution of 7.43 mol L(-1) ammonium hydroxide and 2.06 mol L(-1) hydrofluoric acid. This enhancement of capacitance was attributed to the synergistic effects of an increased electrochemical activity due to the formation of surface N- and F-functional groups and increased, specific surface area, and mesopore volumes, all of which resulted from the amino-fluorination of the electrode material. Copyright © 2012 Elsevier Inc. All rights reserved.

Molecular Mechanism Responsible for Reentrance to Ia3d Gyroid Phase in Cubic Mesogen BABH(n)

NASA Astrophysics Data System (ADS)

Nakazawa, Yuri; Yamamura, Yasuhisa; Kutsumizu, Shoichi; Saito, Kazuya

2012-09-01

Maximum entropy analyses of small-angle X-ray diffraction patterns of a series of title compounds [1,2-bis(4'-n-alkyloxybenzoyl)hydrazine, n: number of carbon atoms in an alkyl group] yield a new description of the so-called gyroid phase. The structure is described as two sets of connected triangles, instead of jungle gyms consisting of rods, embedded in two spaces separated by a mathematical gyroid. The reconstructed electron density provides new evidence of molecular packing: While molecules having short alkyl chains laterally aggregate to form single layers of triangular shape with nearly vertical alignments, those with long chains split into two groups on both sides of the triangular planes. The formation of double layers of the molecular cores is tolerable with the possible formation of hydrogen bonds between shifted molecules, and adjusts the volume fraction of the core part to attain the stability of the reentrant gyroid phase upon chain elongation.

One-by-one imprinting in two eccentric layers of hollow core-shells: Sequential electroanalysis of anti-HIV drugs.

PubMed

Singh, Kislay; Jaiswal, Swadha; Singh, Richa; Fatma, Sana; Prasad, Bhim Bali

2018-07-15

Double layered one-by-one imprinted hollow core-shells@ pencil graphite electrode was fabricated for sequential sensing of anti-HIV drugs. For this, two eccentric layers were developed on the surface of vinylated silica nanospheres to obtain double layered one-by-one imprinted solid core-shells. This yielded hollow core-shells on treatment with hydrofluoric acid. The modified hollow core-shells (single layered dual imprinted) evolved competitive diffusion of probe/analyte molecules. However, the corresponding double layered one-by-one imprinted hollow core-shells (outer layer imprinted with Zidovudine, and inner layer with Lamivudine) were found relatively better owing to their bilateral diffusions into molecular cavities, without any competition. The entire work is based on differential pulse anodic stripping voltammetry at double layered one-by-one imprinted hollow core-shells. This resulted in indirect detection of electro inactive targets with limits of detection as low as 0.91 and 0.12 (aqueous sample), 0.94 and 0.13 (blood serum), and 0.99 and 0.20 ng mL -1 (pharmaceutics) for lamivudine and zidovudine, respectively in anti-HIV drug combination. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of factors influencing the bond strength in roll bonding processes

NASA Astrophysics Data System (ADS)

Khaledi, Kavan; Wulfinghoff, Stephan; Reese, Stefanie

2018-05-01

Cold Roll Bonding (CRB) is recognized as an industrial technique in which the metal sheets are joined together in order to produce laminate metal composites. In this technique, a metallurgical bond resulting from severe plastic deformation is formed between the rolled metallic layers. The main objective of this paper is to analyse different factors which may affect the bond formation in rolling processes. To achieve this goal, first, an interface model is employed which describes both the bonding and debonding. In this model, the bond strength evolution between the metallic layers is calculated based on the film theory of bonding. On the other hand, the debonding process is modelled by means of a bilinear cohesive zone model. In the numerical section, different scenarios are taken into account to model the roll bonding process of metal sheets. The numerical simulation includes the modelling of joining during the roll bonding process followed by debonding in a Double Cantilever Beam (DCB) peeling test. In all simulations, the metallic layers are regarded as elastoplastic materials subjected to large plastic deformations. Finally, the effects of some important factors on the bond formation are numerically investigated.

Hydroxyapatite coatings for marble protection: Optimization of calcite covering and acid resistance

NASA Astrophysics Data System (ADS)

Graziani, Gabriela; Sassoni, Enrico; Franzoni, Elisa; Scherer, George W.

2016-04-01

Hydroxyapatite (HAP) has a much lower dissolution rate and solubility than calcite, especially in an acidic environment, so it has been proposed for the protection of marble against acidic rain corrosion. Promising results were obtained, but further optimization is necessary as the treated layer is often incomplete, cracked and/or porous. In this paper, several parameters were investigated to obtain a coherent, uncracked layer, and to avoid the formation of metastable, soluble phases instead of HAP: the role of the pH of the starting solution; the effect of organic and inorganic additions, and in particular that of ethanol, as it is reported to adsorb on calcite, hence possibly favoring the growth of the HAP layer. Finally, a double application of the treatment was tested. Results were compared to those obtained with ammonium oxalate treatment, widely investigated for marble protection. Results indicate that adding small amounts of ethanol to the formulation remarkably increases the acid resistance of treated samples, and yields better coverage of the surface without crack formation. The effectiveness of the treatment is further enhanced when a second treatment is applied. The efficacy of ethanol-doped DAP mixtures was found to be remarkably higher than that of ammonium oxalate based treatments.

Observation of warm, higher energy electrons transiting a double layer in a helicon plasma

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

Sung, Yung-Ta, E-mail: ysung2@wisc.edu; Li, Yan; Scharer, John E.

2015-03-15

Measurements of an inductive RF helicon argon plasma double layer with two temperature electron distributions including a fast (>80 eV) tail are observed at 0.17 mTorr Ar pressure. The fast, untrapped electrons observed downstream of the double layer have a higher temperature (13 eV) than the trapped (T{sub e} = 4 eV) electrons. The reduction of plasma potential and density observed in the double layer region would require an upstream temperature ten times the measured 4 eV if occurring via Boltzmann ambipolar expansion. The experimental observation in Madison helicon experiment indicates that fast electrons with substantial density fractions can be created at low helicon operating pressures.

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

Baalrud, S. D.; Lafleur, T.; Boswell, R. W.

Current-free double layers of the type reported in plasmas in the presence of an expanding magnetic field [C. Charles and R. W. Boswell, Appl. Phys. Lett. 82, 1356 (2003)] are modeled theoretically and with particle-in-cell/Monte Carlo simulations. Emphasis is placed on determining what mechanisms affect the electron velocity distribution function (EVDF) and how the EVDF influences the double layer. A theoretical model is developed based on depletion of electrons in certain velocity intervals due to wall losses and repletion of these intervals due to ionization and elastic electron scattering. This model is used to predict the range of neutral pressuresmore » over which a double layer can form and the electrostatic potential drop of the double layer. These predictions are shown to compare well with simulation results.« less

RECONNECTION-DRIVEN DOUBLE LAYERS IN THE STRATIFIED PLASMA OF THE SOLAR TRANSITION REGION: SUPPLY OF HOT PLASMA INTO THE CORONA

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

Singh, Nagendra

A novel mechanism for the supply of hot plasma into the corona from the chromosphere is suggested here; the mechanism involves collisionless magnetic reconnection (CMR) in the transition region (TR) followed by double layer (DL) formation in the enhanced expansion of the chromospheric cold plasma mixed with CMR-heated hot electrons. It is well known that (i) the CMR produces energetic electrons and (ii) DLs naturally form in expanding dense plasmas containing a minor population of hot electrons. We apply these plasma physics facts to the dynamics of stratified plasma in the TR. In the TR where densities fall below ∼10{supmore » 16} m{sup −3}, all collisional mean-free paths, electron–ion, ion–neutral, and electron–neutral, become long enough to render plasma collisionless at kinetic scale lengths, making CMR and DL formation possible. The DLs accelerate the chromospheric cold ions to energies comparable to the energy of the hot electrons. When the upflowing energized ions neutralized by the escaping hot electrons thermalize, the resulting hot tenuous plasma supplies an energy flux ∼3 × 10{sup 5} erg cm{sup −2} s{sup −1} = 3 × 10{sup 2} J m{sup −2} s{sup −1} into the corona. The CMR–DL mechanism introduces sudden transitions in the TR as microstructures in both density and energy. The global transition in the TR could be a fractal structure containing such microscopic features. If not impossible, it is difficult to measure such microstructures, but it seems that the coronal heating begins in the nearly collisionless TR by CMR and DL formation.« less

The image-forming mirror in the eye of the scallop

NASA Astrophysics Data System (ADS)

Palmer, Benjamin A.; Taylor, Gavin J.; Brumfeld, Vlad; Gur, Dvir; Shemesh, Michal; Elad, Nadav; Osherov, Aya; Oron, Dan; Weiner, Steve; Addadi, Lia

2017-12-01

Scallops possess a visual system comprising up to 200 eyes, each containing a concave mirror rather than a lens to focus light. The hierarchical organization of the multilayered mirror is controlled for image formation, from the component guanine crystals at the nanoscale to the complex three-dimensional morphology at the millimeter level. The layered structure of the mirror is tuned to reflect the wavelengths of light penetrating the scallop’s habitat and is tiled with a mosaic of square guanine crystals, which reduces optical aberrations. The mirror forms images on a double-layered retina used for separately imaging the peripheral and central fields of view. The tiled, off-axis mirror of the scallop eye bears a striking resemblance to the segmented mirrors of reflecting telescopes.

Investigation of the graphene-electrolyte interface in Li-air batteries: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Pavlov, S. V.; Kislenko, S. A.

2018-01-01

In this work the behavior of the main reactants (Li+, O2) of the oxygen reduction reaction (ORR) in acetonitrile solvent near the multi-layer graphene edge has been studied. It was observed by molecular dynamics simulations that the concentration distributions of the Li+ and O2 represent a “chessboard” structure. It was ascertained that the concentrations of the lithium ions and oxygen molecules reach their maximum values near the graphene edges pushed out from the surface, which may act as nucleation centers for the formation of crystalline products of the ORR. The maps of the free energy were estimated for the Li+ and O2. Energy optimal trajectories for the adsorption of oxygen molecules and lithium ions were found. Moreover, the distributions of the electric potential were obtained near the following carbon surfaces: single- and multi-layer graphene edge, graphene plane, which shows the qualitative differences in the double-layer structure.

MgO-templated carbon as a negative electrode material for Na-ion capacitors

NASA Astrophysics Data System (ADS)

Kado, Yuya; Soneda, Yasushi

2016-12-01

In this study, MgO-templated carbon with different pore structures was investigated as a negative electrode material for Na-ion capacitors. With increasing the Brunauer-Emmett-Teller surface area, the irreversible capacity increased, and the coulombic efficiency of the 1st cycle decreased because of the formation of solid electrolyte interface layers. MgO-templated carbon annealed at 1000 °C exhibited the highest capacity and best rate performance, suggesting that an appropriate balance between surface area and crystallinity is imperative for fast Na-ion storage, attributed to the storage mechanism: combination of non-faradaic electric double-layer capacitance and faradaic Na intercalation in the carbon layers. Finally, a Na-ion capacitor cell using MgO-templated carbon and activated carbon as the negative and positive electrodes, respectively, exhibited an energy density at high power density significantly greater than that exhibited by the cell using a commercial hard carbon negative electrode.

Complexes of dipolar excitons in layered quasi-two-dimensional nanostructures

NASA Astrophysics Data System (ADS)

Bondarev, Igor V.; Vladimirova, Maria R.

2018-04-01

We discuss neutral and charged complexes (biexcitons and trions) formed by indirect excitons in layered quasi-two-dimensional semiconductor heterostructures. Indirect excitons—long-lived neutral Coulomb-bound pairs of electrons and holes of different layers—have been known for semiconductor coupled quantum wells and have recently been reported for van der Waals heterostructures such as double bilayer graphene and transition-metal dichalcogenides. Using the configuration space approach, we derive the analytical expressions for the trion and biexciton binding energies as a function of interlayer distance. The method captures essential kinematics of complex formation to reveal significant binding energies, up to a few tens of meV for typical interlayer distances ˜3 -5 Å , with the trion binding energy always being greater than that of the biexciton. Our results can contribute to the understanding of more complex many-body phenomena such as exciton Bose-Einstein condensation and Wigner-like electron-hole crystallization in layered semiconductor heterostructures.

The importance of the tropopause inversion layer in double tropopause formation, an observational analysis

NASA Astrophysics Data System (ADS)

Peevey, T. R.; Gille, J. C.

2012-12-01

Over the past decade the tropopause inversion layer (TIL), a layer of enhanced stability above the thermal tropopause, has been studied in earnest. This atmospheric feature is located within the upper troposphere lower stratosphere (UTLS) region of the atmosphere, a region of key importance for the Earth's radiative budget and hence the climate system. Another atmospheric feature of similar interest to the UTLS community is the double tropopause (DT). A recent modeling studied looked at the development of the DT during the LC1 and LC2 lifecycles and found that the DT would not form without the presence of the TIL and that as the TIL increased in strength so did the DT frequency. This study builds on that recent work by analyzing this relationship using observations to first see if the relationship exists and then to understand why it does exist. For this study HIRDLS temperature data is primarily used and shows that as the strength/stability of the TIL increases in the extratropics so does the frequency of DTs. Other datasets, such as COSMIC and WACCM, are also used in this work to verify these results since HIRDLS could miss shallow (<1 km) TIL layers. The relationship between the TIL and the DT is analyzed further by examining vertical profiles within specified latitude regions and by examining events that specifically highlight their relationship. Further research is already planned which will expand upon this study using model simulations to track air movement within these UTLS structures.

Confirmation of theoretical colour predictions for layering dental composite materials.

PubMed

Mikhail, Sarah S; Johnston, William M

2014-04-01

The aim of this study is to confirm the theoretical colour predictions for single and double layers of dental composite materials on an opaque backing. Single and double layers of composite resins were fabricated, placed in optical contact with a grey backing and measured for spectral radiance. The spectral reflectance and colour were directly determined. Absorption and scattering coefficients as previously reported, the measured thickness of the single layers and the effective reflectance of the grey backing were utilized to theoretically predict the reflectance of the single layer using corrected Kubelka-Munk reflectance theory. For double layers the predicted effective reflectance of the single layer was used as the reflectance of the backing of the second layer and the thickness of the second layer was used to predict the reflectance of the double layer. Colour differences, using both the CIELAB and CIEDE2000 formulae, measured the discrepancy between each directly determined colour and its corresponding theoretical colour. The colour difference discrepancies generally ranged around the perceptibility threshold but were consistently below the respective acceptability threshold. This theory can predict the colour of layers of composite resin within acceptability limits and generally also within perceptibility limits. This theory could therefore be incorporated into computer-based optical measuring instruments that can automate the shade selections for layers of a more opaque first layer under a more translucent second layer for those clinical situations where an underlying background colour and a desirable final colour can be measured. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improved Electrochemical Cycling Durability in a Nickel Oxide Double-Layered Film.

PubMed

Hou, Shuai; Zhang, Xiang; Tian, Yanlong; Zhao, Jiupeng; Geng, Hongbin; Qu, Huiying; Zhang, Hangchuan; Zhang, Kun; Wang, Binsheng; Gavrilyuk, Alexander; Li, Yao

2017-11-16

For the first time, a crystalline-amorphous double-layered NiO x film has been prepared by reactive radio frequency magnetron sputtering. This film has exhibited improved electrochemical cycling durability, whereas other electrochromic parameters have been maintained at the required level, namely, a short coloration/bleaching time (0.8 s/1.1 s) and an enhanced transmittance modulation range (62.2 %) at λ=550 nm. Additionally, the double-layered film has shown better reversibility than that of amorphous and crystalline single-layered films. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of DNA-Reactive Metabolites from Nitrosamine and Styrene Using Voltammetric DNA/Microsomes Sensors

PubMed Central

Krishnan, Sadagopan; Bajrami, Besnik; Mani, Vigneshwaran; Pan, Shenmin; Rusling, James F.

2012-01-01

Voltammetric sensors made with films of polyions, double-stranded DNA and liver microsomes adsorbed layer-by-layer onto pyrolytic graphite electrodes were evaluated for reactive metabolite screening. This approach features simple, inexpensive screening without enzyme purification for applications in drug or environmental chemical development. Cytochrome P450 enzymes (CYPs) in the liver microsomes were activated by an NADPH regenerating system or by electrolysis to metabolize model carcinogenic compounds nitrosamine and styrene. Reactive metabolites formed in the films were trapped as adducts with nucleobases on DNA. The DNA damage was detected by square-wave voltammetry (SWV) using Ru(bpy)32+ as a DNA-oxidation catalyst. These sensors showed a larger rate of increase in signal vs. reaction time for a highly toxic nitrosamine than for the moderately toxic styrene due to more rapid reactive metabolite-DNA adduct formation. Results were consistent with reported in vivo TD50 data for the formation of liver tumors in rats. Analogous polyion/ liver microsome films prepared on 500 nm silica nanoparticles (nanoreactors) and reacted with nitrosamine or styrene, provided LC-MS or GC analyses of metabolite formation rates that correlated well with sensor response. PMID:23100998

In situ synthesized heteropoly acid/polyaniline/graphene nanocomposites to simultaneously boost both double layer- and pseudo-capacitance for supercapacitors.

PubMed

Cui, Zhiming; Guo, Chun Xian; Yuan, Weiyong; Li, Chang Ming

2012-10-05

It is challenging to simultaneously increase double layer- and pseudo-capacitance for supercapacitors. Phosphomolybdic acid/polyaniline/graphene nanocomposites (PMo(12)-PANI/GS) were prepared by using PMo(12) as a bifunctional reagent for not only well dispersing graphene for high electrochemical double layer capacitance but also in situ chemically polymerizing aniline for high pseudocapacitance, resulting in a specific capacitance of 587 F g(-1), which is ~1.5 and 6 times higher than that of PANI/GS (392 F g(-1)) and GS (103 F g(-1)), respectively. The nanocomposites also exhibit good reversibility and stability. Other kinds of heteropolyacids such as molybdovanadophosphoric acids (PMo(12-x)V(x), x = 1, 2 and 3) were also used to prepare PMo(12-x)V(x)-PANI/GS nanocomposites, also showing enhanced double layer- and pseudo-capacitance. This further proves the proposed concept to simultaneously boost both double layer- and pseudo-capacitance and demonstrates that it could be a universal approach to significantly improve the capacitance for supercapacitors.

Double-diffusive layers in the Adriatic Sea

NASA Astrophysics Data System (ADS)

Carniel, Sandro; Sclavo, Mauro; Kantha, Lakshmi; Prandke, Hartmut

2008-01-01

A microstructure profiler was deployed to make turbulence measurements in the upper layers of the southern Adriatic Sea in the Mediterranean during the Naval Research Laboratory (NRL) DART06A (Dynamics of the Adriatic in Real Time) winter cruise in March 2006. Measurements in the Po river plume along the Italian coast near the Gargano promontory displayed classic double-diffusive layers and staircase structures resulting from the relatively colder and fresher wintertime Po river outflow water masses overlying warmer and more saline water masses from the Adriatic Sea. We report here on the water mass and turbulence structure measurements made both in the double-diffusive interfaces and the adjoining mixed layers in the water columns undergoing double-diffusive convection (DDC). This dataset augments the relatively sparse observations available hitherto on the diffusive layer type of DDC. Measured turbulence diffusivities are consistent with those from earlier theoretical and experimental formulations, suggesting that the wintertime Po river plume is a convenient and easily accessible place to study double diffusive convective processes of importance to mixing in the interior of many regions of the global oceans.

Layered assembly of graphene oxide and Co-Al layered double hydroxide nanosheets as electrode materials for supercapacitors.

PubMed

Wang, Lei; Wang, Dong; Dong, Xin Yi; Zhang, Zhi Jun; Pei, Xian Feng; Chen, Xin Jiang; Chen, Biao; Jin, Jian

2011-03-28

An innovative strategy of fabricating electrode material by layered assembling two kinds of one-atom-thick sheets, carboxylated graphene oxide (GO) and Co-Al layered double hydroxide nanosheet (Co-Al LDH-NS) for the application as a pseudocapacitor is reported. The Co-Al LDH-NS/GO composite exhibits good energy storage properties.

Effect of shock interactions on mixing layer between co-flowing supersonic flows in a confined duct

NASA Astrophysics Data System (ADS)

Rao, S. M. V.; Asano, S.; Imani, I.; Saito, T.

2018-03-01

Experiments are conducted to observe the effect of shock interactions on a mixing layer generated between two supersonic streams of Mach number M _{1} = 1.76 and M _{2} = 1.36 in a confined duct. The development of this mixing layer within the duct is observed using high-speed schlieren and static pressure measurements. Two-dimensional, compressible Reynolds averaged Navier-Stokes equations are solved using the k-ω SST turbulence model in Fluent. Further, adverse pressure gradients are imposed by placing inserts of small (<7% of duct height) but finite (> boundary layer thickness) thickness on the walls of the test section. The unmatched pressures cause the mixing layer to bend and lead to the formation of shock structures that interact with the mixing layer. The mixing layer growth rate is found to increase after the shock interaction (nearly doubles). The strongest shock is observed when a wedge insert is placed in the M _{2} flow. This shock interacts with the mixing layer exciting flow modes that produce sinusoidal flapping structures which enhance the mixing layer growth rate to the maximum (by 1.75 times). Shock fluctuations are characterized, and it is observed that the maximum amplitude occurs when a wedge insert is placed in the M _{2} flow.

Effect of different alloyed layers on the high temperature oxidation behavior of newly developed Ti 2AlNb-based alloys

NASA Astrophysics Data System (ADS)

Wu, Hongyan; Zhang, Pingze; Zhao, Haofeng; Wang, Ling; Xie, Aigen

2011-01-01

The application of titanium aluminide orthorhombic alloys (O-phase alloys) as potential materials in aircraft and jet engines was limited by their poor oxidation resistance at high temperature. The Ti 2AlNb-based alloys were chromised (Cr), chromium-tungstened (Cr-W) and nickel-chromised (Ni-Cr) by the double glow plasma surface alloying process to improve their high temperature oxidation resistance. The discontinuous oxidative behavior of Cr, Cr-W and Ni-Cr alloyed layers on Ti 2AlNb-based alloy at 1093 K was explored in this study. After exposing at 1093 K, the TiO 2 layer was formed on the bare alloy and accompanied by the occurrence of crack, which promoted oxidation rate. The oxidation behavior of Ti 2AlNb-based alloys was improved by surface alloying due to the formation of protective Al 2O 3 scale or continuous and dense NiCr 2O 4 film. The Ni-Cr alloyed layer presented the best high-temperature oxidation resistance among three alloyed layers.

Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

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

Rufai, O. R.; Bharuthram, R.; Singh, S. V.

2012-12-15

Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to bemore » 49 mV/m which is in agreement of the Viking observations in this region.« less

Design and characterization of a biodegradable double-layer scaffold aimed at periodontal tissue-engineering applications.

PubMed

Requicha, João F; Viegas, Carlos A; Hede, Shantesh; Leonor, Isabel B; Reis, Rui L; Gomes, Manuela E

2016-05-01

The inefficacy of the currently used therapies in achieving the regeneration ad integrum of the periodontium stimulates the search for alternative approaches, such as tissue-engineering strategies. Therefore, the core objective of this study was to develop a biodegradable double-layer scaffold for periodontal tissue engineering. The design philosophy was based on a double-layered construct obtained from a blend of starch and poly-ε-caprolactone (30:70 wt%; SPCL). A SPCL fibre mesh functionalized with silanol groups to promote osteogenesis was combined with a SPCL solvent casting membrane aiming at acting as a barrier against the migration of gingival epithelium into the periodontal defect. Each layer of the double-layer scaffolds was characterized in terms of morphology, surface chemical composition, degradation behaviour and mechanical properties. Moreover, the behaviour of seeded/cultured canine adipose-derived stem cells (cASCs) was assessed. In general, the developed double-layered scaffolds demonstrated adequate degradation and mechanical behaviour for the target application. Furthermore, the biological assays revealed that both layers of the scaffold allow adhesion and proliferation of the seeded undifferentiated cASCs, and the incorporation of silanol groups into the fibre-mesh layer enhance the expression of a typical osteogenic marker. This study allowed an innovative construct to be developed, combining a three-dimensional (3D) scaffold with osteoconductive properties and with potential to assist periodontal regeneration, carrying new possible solutions to current clinical needs. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

Simultaneous control of thermoelectric properties in p- and n-type materials by electric double-layer gating: New design for thermoelectric device

NASA Astrophysics Data System (ADS)

Takayanagi, Ryohei; Fujii, Takenori; Asamitsu, Atsushi

2015-05-01

We report a novel design of a thermoelectric device that can control the thermoelectric properties of p- and n-type materials simultaneously by electric double-layer gating. Here, p-type Cu2O and n-type ZnO were used as the positive and negative electrodes of the electric double-layer capacitor structure. When a gate voltage was applied between the two electrodes, holes and electrons accumulated on the surfaces of Cu2O and ZnO, respectively. The thermopower was measured by applying a thermal gradient along the accumulated layer on the electrodes. We demonstrate here that the accumulated layers worked as a p-n pair of the thermoelectric device.

Photocatalytic property and structural stability of CuAl-based layered double hydroxides

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

Lv, Ming; Liu, Haiqiang, E-mail: Liuhaiqiang1980@126.com

2015-07-15

Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV–Vis diffuse reflectance spectrum (UV–vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO{sub 2} reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210more » mmol/g h, which was high efficient. In addition, the influence of the different M{sup 2+} on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials. - Graphical abstract: The host–guest calculation models and XRD patterns of CuMAl-LDHs: CuMgAl-LDHs (a), CuZnAl-LDHs (b) and CuNiAl-LDHs (c). - Highlights: • Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) has been synthesized. • CuMgNi shows narrower band gap and more excellent textural properties than other LDHs. • The band gap: CuMgAl« less

Mechanisms for the Dissipation of Alfven Waves in Near-Earth Space Plasma

NASA Technical Reports Server (NTRS)

Singh, Nagendra; Khazanov, George; Krivorutsky, E. N.; Davis, John M. (Technical Monitor)

2002-01-01

Alfven waves are a major mechanism for the transport of electromagnetic energy from the distant part of the magnetosphere to the near-Earth space. This is especially true for the auroral and polar regions of the Earth. However, the mechanisms for their dissipation have remained illusive. One of the mechanisms is the formation of double layers when the current associated with Alfven waves in the inertial regime interact with density cavities, which either are generated nonlinearly by the waves themselves or are a part of the ambient plasma turbulence. Depending on the strength of the cavities, weak and strong double layers could form. Such double layers are transient; their lifetimes depend on that of the cavities. Thus they impulsively accelerate ions and electrons. Another mechanism is the resonant absorption of broadband Alfven- wave noise by the ions at the ion cyclotron frequencies. But this resonant absorption may not be possible for the very low frequency waves, and it may be more suited for electromagnetic ion cyclotron waves. A third mechanism is the excitation of secondary waves by the drifts of electrons and ions in the Alfven wave fields. It is found that under suitable conditions, the relative drifts between different ion species and/or between electrons and ions are large enough to drive lower hybrid waves, which could cause transverse accelerations of ions and parallel accelerations of electrons. This mechanism is being further studied by means of kinetic simulations using 2.5- and 3-D particle-in-cell codes. The ongoing modeling efforts on space weather require quantitative estimates of energy inputs of various kinds, including the electromagnetic energy. Our studies described here contribute to the methods of determining the estimates of the input from ubiquitous Alfven waves.

Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

NASA Astrophysics Data System (ADS)

Shen, H. H.; Liu, L.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

2016-12-01

The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

Impact of inhomogeneity on SH-type wave propagation in an initially stressed composite structure

NASA Astrophysics Data System (ADS)

Saha, S.; Chattopadhyay, A.; Singh, A. K.

2018-02-01

The present analysis has been made on the influence of distinct form of inhomogeneity in a composite structure comprised of double superficial layers lying over a half-space, on the phase velocity of SH-type wave propagating through it. Propagation of SH-type wave in the said structure has been examined in four distinct cases of inhomogeneity viz. when inhomogeneity in double superficial layer is due to exponential variation in density only (Case I); when inhomogeneity in double superficial layers is due to exponential variation in rigidity only (Case II); when inhomogeneity in double superficial layer is due to exponential variation in rigidity, density and initial stress (Case III) and when inhomogeneity in double superficial layer is due to linear variation in rigidity, density and initial stress (Case IV). Closed-form expression of dispersion relation has been accomplished for all four aforementioned cases through extensive application of Debye asymptotic analysis. Deduced dispersion relations for all the cases are found in well-agreement to the classical Love-wave equation. Numerical computation has been carried out to graphically demonstrate the effect of inhomogeneity parameters, initial stress parameters as well as width ratio associated with double superficial layers in the composite structure for each of the four aforesaid cases on dispersion curve. Meticulous examination of distinct cases of inhomogeneity and initial stress in context of considered problem has been carried out with detailed analysis in a comparative approach.

Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

NASA Astrophysics Data System (ADS)

Lee, Seong Yun; Kim, Jae Young; Lee, Jun Young; Song, Ho Jun; Lee, Sangkug; Choi, Kyung Ho; Shin, Gyojic

2014-06-01

An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

Plasmonic layers based on Au-nanoparticle-doped TiO2 for optoelectronics: structural and optical properties.

PubMed

Pedrueza, E; Sancho-Parramon, J; Bosch, S; Valdés, J L; Martinez-Pastor, J P

2013-02-15

The anti-reflective effect of dielectric coatings used in silicon solar cells has traditionally been the subject of intensive studies and practical applications. In recent years the interest has permanently grown in plasmonic layers based on metal nanoparticles, which are shown to increase light trapping in the underlying silicon. In the present work we have combined these two concepts by means of in situ synthesis of Au nanoparticles in a dielectric matrix (TiO2), which is commonly used as an anti-reflective coating in silicon solar cells, and added the third element: a 10-20% porosity in the matrix. The porosity is formed by means of a controllable wet etching by low concentration HF. As a consequence, the experimentally measured reflectance of silicon coated by such a plasmonic layer decreases to practically zero in a broad wavelength region around the localized surface plasmon resonance. Furthermore, we demonstrate that extinction and reflectance spectra of silicon coated by the plasmonic films can be successfully accounted for by means of Fresnel formulae, in which a double refractive index of the metal-dielectric material is used. This double refractive index cannot be explained by effective medium theory (Maxwell-Garnett, for example) and appears when the contribution of Au nanoparticles located at the TiO2/Si interface is high enough to result in formation of interface surface plasmon modes.

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

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

Zhou, Daojin; Cai, Zhao; Bi, Yongmin

Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotentialmore » of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. Finally, this increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.« less

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

DOE PAGES

Zhou, Daojin; Cai, Zhao; Bi, Yongmin; ...

2018-02-02

Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotentialmore » of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. Finally, this increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.« less

The impact of surface chemistry on the performance of localized solar-driven evaporation system

PubMed Central

Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-01-01

This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation. PMID:26337561

The impact of surface chemistry on the performance of localized solar-driven evaporation system.

PubMed

Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-09-04

This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation.

Application of Electric Double-layer Capacitors for Energy Storage on Electric Railway

NASA Astrophysics Data System (ADS)

Hase, Shin-Ichi; Konishi, Takeshi; Okui, Akinobu; Nakamichi, Yoshinobu; Nara, Hidetaka; Uemura, Tadashi

The methods to stabilize power sources, which are the measures against voltage drop, power loading fluctuation, regeneration power lapse and so on, have been important issues in DC feeding circuits. Therefore, an energy storage medium that uses power efficiently and reduces above-mentioned problems is much concerned about. In recent years, development of energy storage medium is remarkable for drive-power supplies of electric vehicles. A number of applications of energy storage, for instance, battery and flywheel, have been investigated so far. A large-scale electric double-layer capacitor which is rapidly charged and discharged and offers long life, maintenance-free, low pollution and high efficiency, has been developed in wide range. We have compared the ability to charge batteries and electric double-layer capacitors. Therefore, we carried out fundamental studies about electric double-layer capacitors and its control. And we produced a prototype of energy storage for the DC electric railway system that consists of electric double-layer capacitors, diode bridge rectifiers, chopper system and PWM converters. From the charge and discharge tests of the prototype, useful information was obtained. This paper describes its characteristics and experimental results of energy storage system.

Hybrid Dye-Sensitized Solar Cells Consisting of Double Titania Layers for Harvesting Light with Wide Range of Wavelengths

NASA Astrophysics Data System (ADS)

Sadamasu, Kengo; Inoue, Takafumi; Ogomi, Yuhei; Pandey, Shyam S.; Hayase, Shuzi

2011-02-01

We report a hybrid dye-sensitized solar cell consisting of double titania layers (top and bottom layers) stained with two dyes. A top layer fabricated on a glass was mechanically pressed with a bottom layer fabricated on a glass cloth. The glass cloth acts as a supporter of a porous titania layer as well as a holder of electrolyte. The incident photon to current efficiency (IPCE) curve had two peaks corresponding to those of the two dyes, which demonstrates that electrons are collected from both the top and bottom layers.

Effect of carbon entrapped in Co-Al double oxides on structural restacking and electrochemical performances

NASA Astrophysics Data System (ADS)

Su, Ling-Hao; Zhang, Xiao-Gang

Co-Al layered double hydroxides (LDH) were synthesized from nitrates and sodium benzoate by direct coprecipitation, and heated at 600 °C for 3 h in argon gas flow to obtain Co-Al double oxides. The effect of carbon, created during the pyrolysis of benzoate and inserted in resulting double oxides, on structural reconstruction was investigated by X-ray diffraction, scanning electron microscope, Raman spectroscopy, and infrared spectroscopy techniques. It is horizontal arrangement rather than vertical dilayer orientation in the interlayer spacing that was adopted by benzoate. An abnormal phenomenon was found that when immersed in aqueous 6 M KOH solution in air, the double oxides restacked to Co-Al layered double hydroxides with more regular crystal than before. The reason is believed that carbon was confined in the matrix of resulting double oxides, which prevented further collapse of the layered structure. Cyclic voltammetries (CV) and constant current charge/discharge measurements reveal that the restacked Co-Al layered double hydroxide has good long-life capacitive performance with a capacitance up to 145 F g -1 even at a large current of 2 A g -1. In addition, two clear slopes in chronoampermetric test demonstrated two different diffusion coefficients, explaining the slope of about 118.4 mV in the plot of formal potential E f versus pOH.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

The measurement of boundary layers on a compressor blade in cascade at high positive incidence angle. 2: Data report

NASA Technical Reports Server (NTRS)

Deutsch, S.; Zierke, W. C.

1986-01-01

Boundary layer and near-wake velocity measurements have been made in the well documented flow field about a double circular arc compressor blade in cascade, at an incidence angle of 5 deg. and a chord Reynolds number of 500,000. In Part 2 of this report these measurements were analyzed and presented in standard graphical format. The flow geometry, measurement techniques, and physics of the flow field were also discussed. In this, part 2 of the report, raw and analyzed data are presented in tabulated form in an attempt to make this data more accessible to computational comparison. Also included in part 2 is a description of the data analysis employed. A computer tape containing the data is available.

Surface Nb-ALLOYING on 0.4C-13Cr Stainless Steel: Microstructure and Tribological Behavior

NASA Astrophysics Data System (ADS)

Yu, Shengwang; You, Kai; Liu, Xiaozhen; Zhang, Yihui; Wang, Zhenxia; Liu, Xiaoping

2016-02-01

0.4C-13Cr stainless steel was alloyed with niobium using double glow plasma surface alloying and tribological properties of Nb-alloyed steel such as hardness, friction and wear were measured. Effects of the alloying temperature on microstructure and the tribological behavior of the alloyed steel were investigated compared with untreated steel. Formation mechanisms of Nb-alloyed layers and increased wear resistance were also studied. The result shows that after surface Nb-alloying treatment, the 0.4C-13Cr steel exhibits a diffusion adhesion at the alloyed layer/substrate interface and improved tribological property. The friction coefficient of Nb-alloyed steel is decreased by about 0.3-0.45 and the wear rate after Nb-alloying is only 2-5% of untreated steel.

A review of molecular modelling of electric double layer capacitors.

PubMed

Burt, Ryan; Birkett, Greg; Zhao, X S

2014-04-14

Electric double-layer capacitors are a family of electrochemical energy storage devices that offer a number of advantages, such as high power density and long cyclability. In recent years, research and development of electric double-layer capacitor technology has been growing rapidly, in response to the increasing demand for energy storage devices from emerging industries, such as hybrid and electric vehicles, renewable energy, and smart grid management. The past few years have witnessed a number of significant research breakthroughs in terms of novel electrodes, new electrolytes, and fabrication of devices, thanks to the discovery of innovative materials (e.g. graphene, carbide-derived carbon, and templated carbon) and the availability of advanced experimental and computational tools. However, some experimental observations could not be clearly understood and interpreted due to limitations of traditional theories, some of which were developed more than one hundred years ago. This has led to significant research efforts in computational simulation and modelling, aimed at developing new theories, or improving the existing ones to help interpret experimental results. This review article provides a summary of research progress in molecular modelling of the physical phenomena taking place in electric double-layer capacitors. An introduction to electric double-layer capacitors and their applications, alongside a brief description of electric double layer theories, is presented first. Second, molecular modelling of ion behaviours of various electrolytes interacting with electrodes under different conditions is reviewed. Finally, key conclusions and outlooks are given. Simulations on comparing electric double-layer structure at planar and porous electrode surfaces under equilibrium conditions have revealed significant structural differences between the two electrode types, and porous electrodes have been shown to store charge more efficiently. Accurate electrolyte and electrode models which account for polarisation effects are critical for future simulations which will consider more complex electrode geometries, particularly for the study of dynamics of electrolyte transport, where the exclusion of electrode polarisation leads to significant artefacts.

Computational study of the shift of the G band of double-walled carbon nanotubes due to interlayer interactions

NASA Astrophysics Data System (ADS)

Popov, Valentin N.; Levshov, Dmitry I.; Sauvajol, Jean-Louis; Paillet, Matthieu

2018-04-01

The interactions between the layers of double-walled carbon nanotubes induce a measurable shift of the G bands relative to the isolated layers. While experimental data on this shift in freestanding double-walled carbon nanotubes has been reported in the past several years, a comprehensive theoretical description of the observed shift is still lacking. The prediction of this shift is important for supporting the assignment of the measured double-walled nanotubes to particular nanotube types. Here, we report a computational study of the G-band shift as a function of the semiconducting inner layer radius and interlayer separation. We find that with increasing interlayer separation, the G band shift decreases, passes through zero and becomes negative, and further increases in absolute value for the wide range of considered inner layer radii. The theoretical predictions are shown to agree with the available experimental data within the experimental uncertainty.

Cursory examination of the zeta potential behaviors of two optical materials

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

Tesar, A.; Oja, T.

1992-01-02

When an oxide surface is placed in water, a difference in potential across the interface occurs due to dipole orientation. Hydroxyl groups or bound oxygen atoms on the oxide surface will orient adjacent water molecules which balance the dipole charge. This occurs over some small distance called the electrical double layer. Trace amounts of high field strength ions present in the vicinity of the double layer can have significant effects on the double layer. When there is movement of the oxide surface with respect to the water, a shearing of the double layer occurs. The electrical potential at this surfacemore » of shear is termed the zeta potential. The impetus for this study was to document the zeta potential behavior in water of two optical materials. (1) a multicomponent phosphate glass; and (2) Zerodur, a silicate glass-ceramic.« less

Determination of effective mechanical properties of a double-layer beam by means of a nano-electromechanical transducer

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

Hocke, Fredrik; Pernpeintner, Matthias; Gross, Rudolf, E-mail: rudolf.gross@wmi.badw.de

We investigate the mechanical properties of a doubly clamped, double-layer nanobeam embedded into an electromechanical system. The nanobeam consists of a highly pre-stressed silicon nitride and a superconducting niobium layer. By measuring the mechanical displacement spectral density both in the linear and the nonlinear Duffing regime, we determine the pre-stress and the effective Young's modulus of the nanobeam. An analytical double-layer model quantitatively corroborates the measured values. This suggests that this model can be used to design mechanical multilayer systems for electro- and optomechanical devices, including materials controllable by external parameters such as piezoelectric, magnetostrictive, or in more general multiferroicmore » materials.« less

Optical trapping forces of a focused azimuthally polarized Bessel-Gaussian beam on a double-layered sphere

NASA Astrophysics Data System (ADS)

Wu, F. P.; Zhang, B.; Liu, Z. L.; Tang, Y.; Zhang, N.

2017-12-01

We calculate the trapping forces exerted by a highly focused Bessel-Gaussian beam on a double-layered sphere by means of vector diffraction integral, T-matrix method and Maxwell stress tensor integral. The Bessel-Gaussian beam is azimuthally polarized. Numerical results predicate that the double-layered sphere with air core can be stably trapped in three-dimensions. The trapping forces and efficiencies are dependent on the refraction index and size of the inner core. The trapping efficiency can be optimized by choosing the refraction indices of the inner core and outer layer. Our computational method can be easily modified for other laser beams and particles with arbitrary geometries and multilayers.

Delamination-restacking behaviour of surfactant intercalated layered hydroxy double salts, M 3Zn 2(OH) 8(surf) 2ṡ2H 2O [M = Ni, Co and surf = dodecyl sulphate (DS), dodecyl benzene sulphonate (DBS)

NASA Astrophysics Data System (ADS)

Rajamathi, Jacqueline T.; Ravishankar, N.; Rajamathi, Michael

2005-02-01

Surfactant anion intercalated nickel-zinc and cobalt-zinc layered hydroxy double salts were prepared through a modified acetate hydrolysis route. These organo-inorganic hybrids delaminate readily in alcohols such as 1-butanol to give stable translucent colloids. The extent of delamination and the stability of the colloids obtained are comparable to what has been observed in the case of layered double hydroxides (LDHs). The original layered solid could be obtained either by evaporation of the colloid or precipitation by the addition of a polar solvent such as acetone.

Mechano-hydrothermal preparation of Li-Al-OH layered double hydroxides

NASA Astrophysics Data System (ADS)

Zhang, Fengrong; Hou, Wanguo

2018-05-01

A mechano-hydrothermal (MHT) method was used to synthesize Li-Al-OH layered double hydroxides (LDHs) from LiOH·H2O, Al(OH)3 and H2O as starting materials. A two-step synthesis was conducted, that is, Al(OH)3 was milled for 1 h, followed by hydrothermal treatment with LiOH·H2O solution. Effects of the LiOH/Al(OH)3 molar ratio (RLi/Al) and hydrothermal temperature (Tht) on the crystallinity, morphology, and composition of the product were examined. The resulting LDHs were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared, and elemental analyses. The results showed that pre-milling plays a key role in the LDH formation during subsequent hydrothermal treatment. The Li/Al molar ratio of the obtained LDHs keeps constant at 0.5, independent from theRLi/Al (0.5-5.0) in the starting materials. An increase in the Tht (20-80 °C) can enhance the crystallinity and morphology regularity of the products. The so-obtained Li-Al-OH LDHs exhibit high crystallinity and well-dispersity, which may have wider applications than the aggregate ones obtained using conventional mechanochemical and Li+-imbibition methods.

Investigation of radiofrequency plasma sources for space travel

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Takahashi, K.

2012-12-01

Optimization of radiofrequency (RF) plasma sources for the development of space thrusters differs from other applications such as plasma processing of materials since power efficiency, propellant usage, particle acceleration or heating become driving parameters. The development of two RF (13.56 MHz) plasma sources, the high-pressure (˜1 Torr) capacitively coupled ‘pocket rocket’ plasma micro-thruster and the low-pressure (˜1 mTorr) inductively coupled helicon double layer thruster (HDLT), is discussed within the context of mature and emerging electric propulsion devices. The density gradient in low-pressure expanding RF plasmas creates an electric field that accelerates positive ions out of the plasma. Generally, the total potential drop is similar to that of a wall sheath allowing the plasma electrons to neutralize the ion beam. A high-pressure expansion with no applied magnetic field can result in large dissociation rates and/or a collimated beam of ions of small area and a flowing heated neutral beam (‘pocket rocket’). A low-pressure expansion dominated by a magnetic field can result in the formation of electric double layers which produce a very directed neutralized beam of ions of large area (HDLT).

A novel carbon electrode material for highly improved EDLC performance.

PubMed

Fang, Baizeng; Binder, Leo

2006-04-20

Porous materials, developed by grafting functional groups through chemical surface modification with a surfactant, represent an innovative concept in energy storage. This work reports, in detail, the first practical realization of a novel carbon electrode based on grafting of vinyltrimethoxysilane (vtmos) functional group for energy storage in electric double layer capacitor (EDLC). Surface modification with surfactant vtmos enhances the hydrophobisation of activated carbon and the affinity toward propylene carbonate (PC) solvent, which improves the wettability of activated carbon in the electrolyte solution based on PC solvent, resulting in not only a lower resistance to the transport of electrolyte ions within micropores of activated carbon but also more usable surface area for the formation of electric double layer, and accordingly, higher specific capacitance, energy density, and power capability available from the capacitor based on modified carbon. Especially, the effects from surface modification become superior at higher discharge rate, at which much better EDLC performance (i.e., much higher energy density and power capability) has been achieved by the modified carbon, suggesting that the modified carbon is a novel and very promising electrode material of EDLC for large current applications where both high energy density and power capability are required.

Restriction Endonucleases from Invasive Neisseria gonorrhoeae Cause Double-Strand Breaks and Distort Mitosis in Epithelial Cells during Infection

PubMed Central

Weyler, Linda; Engelbrecht, Mattias; Mata Forsberg, Manuel; Brehwens, Karl; Vare, Daniel; Vielfort, Katarina; Wojcik, Andrzej; Aro, Helena

2014-01-01

The host epithelium is both a barrier against, and the target for microbial infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae infections disrupt host cell cycle regulation machinery and the infection causes DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release restriction endonucleases that enter the nucleus and damage human chromosomal DNA. Bacterial lysates containing restriction endonucleases were able to fragment genomic DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20 h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and chromosomal instability. These data highlight basic molecular functions of how gonococcal infections affect host cell cycle regulation, cause DNA double strand breaks and predispose cellular malignancies. PMID:25460012

Restriction endonucleases from invasive Neisseria gonorrhoeae cause double-strand breaks and distort mitosis in epithelial cells during infection.

PubMed

Weyler, Linda; Engelbrecht, Mattias; Mata Forsberg, Manuel; Brehwens, Karl; Vare, Daniel; Vielfort, Katarina; Wojcik, Andrzej; Aro, Helena

2014-01-01

The host epithelium is both a barrier against, and the target for microbial infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae infections disrupt host cell cycle regulation machinery and the infection causes DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release restriction endonucleases that enter the nucleus and damage human chromosomal DNA. Bacterial lysates containing restriction endonucleases were able to fragment genomic DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20 h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and chromosomal instability. These data highlight basic molecular functions of how gonococcal infections affect host cell cycle regulation, cause DNA double strand breaks and predispose cellular malignancies.

[Experimental model for the examination of inner pressure tolerance of telescopic anastomosis and other frequently performed anastomosis types of the esophagus].

PubMed

Szúcs, G; Tóth, I; Bráth, E; Gyáni, K; Miko, I

2001-08-01

We have good results with telescopic anastomosis technique in partial oesophagectomies and gastrectomies. As we could not find data about the healing process of telescopic anastomoses so we started experimenting. Inside pressure tolerance was examined immediately after performing anastomoses by measuring the bursting pressure using the organs of pigs slaughtered in the meat industry. Both oesophago-gastrostomies and oesophago-jejunostomies were performed with telescopic, single layer interrupted, single layer continuous, double layer interrupted and double layer continuous-interrupted technique, 9 of each anastomosis. A series of oesophago-jejunostomies were performed with EEA stapler. 99 anastomoses of 11 types were investigated. We found, that the inner pressure tolerance of telescopic oesophago-gastrostomy is better than any other single layer type variant. On the other hand the double layer type variants have much better pressure tolerance than the telescopic and other two type single layer anastomoses. The difference is statistically significant. In oesophago-jejunostomies the pressure tolerance of telescopic anastomosis is better than of the single layer interrupted type but the difference between the telescopic and single layer continuous type anastomoses is not significant. The pressure tolerance of double layer anastomosis is higher than the telescopic one but the difference is significant only in the continuous-interrupted type. The inner pressure tolerance of telescopic and EEA stapler anastomoses are equal. The investigation of additional features in anastomosis healing is in progress.

Theoretical investigation of the formation of basal plane stacking faults in heavily nitrogen-doped 4H-SiC crystals

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

Taniguchi, Chisato; Ichimura, Aiko; Ohtani, Noboru, E-mail: ohtani.noboru@kwansei.ac.jp

The formation of basal plane stacking faults in heavily nitrogen-doped 4H-SiC crystals was theoretically investigated. A novel theoretical model based on the so-called quantum well action mechanism was proposed; the model considers several factors, which were overlooked in a previously proposed model, and provides a detailed explanation of the annealing-induced formation of double layer Shockley-type stacking faults in heavily nitrogen-doped 4H-SiC crystals. We further revised the model to consider the carrier distribution in the depletion regions adjacent to the stacking fault and successfully explained the shrinkage of stacking faults during annealing at even higher temperatures. The model also succeeded inmore » accounting for the aluminum co-doping effect in heavily nitrogen-doped 4H-SiC crystals, in that the stacking fault formation is suppressed when aluminum acceptors are co-doped in the crystals.« less

46 CFR 194.10-25 - Ventilation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... and shall serve no other space. Weather cowls shall be provided with a double layer of wire screen of.... Louvers or weather cowls with a double layer of wire screen of not less than 1/8-inch mesh shall be...

Synthesising methods of layered double hydroxides and its use in the fabrication of dye Sensitised solar cell (DSSC): A short review

NASA Astrophysics Data System (ADS)

George, Giphin; Saravanakumar, M. P.

2017-11-01

The layered double hydroxides (LDH) which are anionic clay substances comprising of stacked cationic layers and interlayer anions. The cationic sheets contain octahedral structure consisting the divalent and trivalent ions in the center and hydroxyl bunches in the corners, gathered by three bonding with the neighbouring octahedra on every side of the layer. The ratio between the quantity of cations and OH- ions is 2:1, so a positive charge shows up on the layer because of the presence of trivalent cations. The interlayer space gives the compensation anions and water molecules, assuring a balanced out layered structure. The LDH materials were successfully synthesised from magnesium, aluminium, zinc and chromium chloride salts utilizing the co-precipitation technique. A Zn-Al LDH was researched as a potential sorbent material. This article reviews the recent advances in the preparation and intercalation of layered double hydroxides and its application in the fabrication of Dye Sensitized Solar Cell (DSSC).

Volume, distribution and acidity of gastric secretion on and off proton pump inhibitor treatment: a randomized double-blind controlled study in patients with gastro-esophageal reflux disease (GERD) and healthy subjects.

PubMed

Steingoetter, Andreas; Sauter, Matthias; Curcic, Jelena; Liu, Dian; Menne, Dieter; Fried, Michael; Fox, Mark; Schwizer, Werner

2015-09-02

Postprandial accumulation of gastric secretions in the proximal stomach above the meal adjacent to the esophagogastric junction (EGJ), referred to as the 'acid pocket', has been proposed as a pathophysiological factor in gastro-esophageal reflux disease (GERD) and as a target for GERD treatment. This study assessed the effect of proton pump inhibitor (PPI) therapy on the volume, distribution and acidity of gastric secretions in GERD and healthy subjects (HS). A randomized, double blind, cross-over study in 12 HS and 12 GERD patients pre-treated with 40 mg pantoprazole (PPI) or placebo b.i.d. was performed. Postprandial secretion volume (SV), formation of a secretion layer and contact between the layer and the EGJ were quantified by Magnetic Resonance Imaging (MRI). Multi-channel pH-monitoring assessed intragastric pH. A distinct layer of undiluted acid secretion was present on top of gastric contents in almost all participants on and off high-dose acid suppression. PPI reduced SV (193 ml to 100 ml, in HS, 227 ml to 94 ml in GERD; p < 0.01) and thickness of the acid layer (26 mm to 7 mm, 36 mm to 9 mm respectively, p < 0.01). No differences in secretion volume or layer thickness were observed between groups; however, off treatment, contact time between the secretion layer and EGJ was 2.6 times longer in GERD compared to HS (p = 0.012). This was not the case on PPI. MRI can visualize and quantify the volume and distribution dynamics of gastric secretions that form a layer in the proximal stomach after ingestion of a liquid meal. The secretion volume and the secretion layer on top of gastric contents is similar in GERD patients and HS; however contact between the layer of undiluted secretion and the EGJ is prolonged in patients. High dose PPI reduced secretion volume by about 50% and reduced contact time between secretion and EGJ towards normal levels. NCT01212614.

Synthesis, crystal structure and optical properties of two new layered cadmium iodates: Cd(IO{sub 3})X (X=Cl, OH)

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

Yang, Bing-Ping, E-mail: ybp@fjirsm.ac.cn; Mao, Jiang-Gao

Systematic explorations of new compounds in the cadmium iodate system by hydrothermal reactions led to two layered iodates, namely, Cd(IO{sub 3})X (X=Cl, OH). Cd(IO{sub 3})Cl crystallizes in the orthorhombic space group Cmca (No. 64) whereas Cd(IO{sub 3})(OH) crystallizes in the orthorhombic space group Pnma (No. 62). Cd(IO{sub 3})Cl displays a unique double layered structure composed of {sup 1}{sub ∞}[Cd−O{sub 3}Cl]{sub n} chains. Cadmium octahedrons form a 1D chain along the a-axis through edge sharing, and such chains are further interconnected via IO{sub 3} groups to form a special double layer on (020) plane. Cd(IO{sub 3})(OH) also exhibits a layered structuremore » that is composed of cadmium cations, IO{sub 3} groups and hydroxyl ions. Within a layer, chains of CdO{sub 6} edge-shared octahedra are observed along the b-axis. And these chains are connected by IO{sub 3} groups into a layer parallel to the bc plane. Spectroscopic characterizations, elemental analysis, and thermogravimetric analysis for the reported two compounds are also presented. - Graphical abstract: Two new layered cadmium iodates Cd(IO{sub 3})X (X=Cl, OH) are reported. Cd(IO{sub 3})Cl features a unique double layered structure whereas Cd(IO{sub 3})(OH) displays an ordinary layered structure. - Highlights: • Two new layered cadmium iodates Cd(IO{sub 3})X (X=Cl, OH) are reported. • Cd(IO{sub 3})Cl features a unique double layered structure. • Cd(IO{sub 3})(OH) displays an ordinary layered structure. • The spectroscopic and thermal properties have been studied in detail.« less

Analytical and Numerical Modeling of Tsunami Wave Propagation for double layer state in Bore

NASA Astrophysics Data System (ADS)

Yuvaraj, V.; Rajasekaran, S.; Nagarajan, D.

2018-04-01

Tsunami wave enters into the river bore in the landslide. Tsunami wave propagation are described in two-layer states. The velocity and amplitude of the tsunami wave propagation are calculated using the double layer. The numerical and analytical solutions are given for the nonlinear equation of motion of the wave propagation in a bore.

Sol-Gel Deposited Double Layer TiO₂ and Al₂O₃ Anti-Reflection Coating for Silicon Solar Cell.

PubMed

Jung, Jinsu; Jannat, Azmira; Akhtar, M Shaheer; Yang, O-Bong

2018-02-01

In this work, the deposition of double layer ARC on p-type Si solar cells was carried out by simple spin coating using sol-gel derived Al2O3 and TiO2 precursors for the fabrication of crystalline Si solar cells. The first ARC layer was created by freshly prepared sol-gel derived Al2O3 precursor using spin coating technique and then second ARC layer of TiO2 was deposited with sol-gel derived TiO2 precursor, which was finally annealed at 400 °C. The double layer Al2O3/TiO2 ARC on Si wafer exhibited the low average reflectance of 4.74% in the wavelength range of 400 and 1000 nm. The fabricated solar cells based on double TiO2/Al2O3 ARC attained the conversion efficiency of ~13.95% with short circuit current (JSC) of 35.27 mA/cm2, open circuit voltage (VOC) of 593.35 mV and fill factor (FF) of 66.67%. Moreover, the fabricated solar cells presented relatively low series resistance (Rs) as compared to single layer ARCs, resulting in the high VOC and FF.

Assembly of purple membranes on polyelectrolyte films.

PubMed

Saab, Marie-belle; Estephan, Elias; Cloitre, Thierry; Legros, René; Cuisinier, Frédéric J G; Zimányi, László; Gergely, Csilla

2009-05-05

The membrane protein bacteriorhodopsin in its native membrane bound form (purple membrane) was adsorbed and incorporated into polyelectrolyte multilayered films, and adsorption was in situ monitored by optical waveguide light-mode spectroscopy. The formation of a single layer or a double layer of purple membranes was observed when adsorbed on negatively or positively charged surfaces, respectively. The purple membrane patches adsorbed on the polyelectrolyte multilayers were also evidenced by atomic force microscopy images. The driving forces of the adsorption process were evaluated by varying the ionic strength of the solution as well as the purple membrane concentration. At high purple membrane concentration, interpenetrating polyelectrolyte loops might provide new binding sites for the adsorption of a second layer of purple membranes, whereas at lower concentrations only a single layer is formed. Negative surfaces do not promote a second protein layer adsorption. Driving forces other than just electrostatic ones, such as hydrophobic forces, should play a role in the polyelectrolyte/purple membrane layering. The subtle interplay of all these factors determines the formation of the polyelectrolyte/purple membrane matrix with a presumably high degree of orientation for the incorporated purple membranes, with their cytoplasmic, or extracellular side toward the bulk on negatively or positively charged polyelectrolyte, respectively. The structural stability of bacteriorhodopsin during adsorption onto the surface and incorporation into the polyelectrolyte multilayers was investigated by Fourier transform infrared spectroscopy in attenuated total reflection mode. Adsorption and incorporation of purple membranes within polyelectrolyte multilayers does not disturb the conformational majority of membrane-embedded alpha-helix structures of the protein, but may slightly alter the structure of the extramembraneous segments or their interaction with the environment. This high stability is different from the lower stability of the predominantly beta-sheet structures of numerous globular proteins when adsorbed onto surfaces.

Interior and Ejecta Morphologies of Impact Craters on Ganymede

NASA Astrophysics Data System (ADS)

Barlow, Nadine G.; Klaybor, K.; Katz-Wigmore, J.

2006-09-01

We are utilizing Galileo SSI imagery of Ganymede to classify impact crater interior and ejecta morphologies. Although we are in the early stages of compiling our Catalog of Impact Craters on Ganymede, some interesting trends are beginning to emerge. Few craters display obvious ejecta morphologies, but 68 craters are classified as single layer ejecta and 3 as double layer ejecta. We see no obvious correlation of layered ejecta morphologies with terrain or latitude. All layered ejecta craters have diameters between 10 and 40 km. Sinuosity ("lobateness") and ejecta extent ("ejecta mobility ratio") of Ganymede layered ejecta craters are lower than for martian layered ejecta craters. This suggests less mobility of ejecta materials on Ganymede, perhaps due to the colder temperatures. Interior structures being investigated include central domes, peaks, and pits. 57 dome craters, 212 central peak craters, and 313 central pit craters have been identified. Central domes occur in 50-100 km diameter craters while peaks are found in craters between 20 and 50 km and central pit craters range between 29 and 74 km in diameter. The Galileo Regio region displays higher concentrations of central dome and central pit craters than other regions we have investigated. 67% of central pit craters studied to date are small pits, where the ratio of pit diameter to crater diameter is <0.2. Craters containing the three interior structures preferentially occur on darker terrain units, suggesting that an ice-silicate composition is more conducive to interior feature formation than pure ice alone. Results of this study have important implications not only for the formation of specific interior and ejecta morphologies on Ganymede but also for analogous features associated with Martian impact craters. This research is funded through NASA Outer Planets Research Program Award #NNG05G116G to N. G. Barlow.

Sedimentation from flocculated suspensions in the presence of settling-driven gravitational interface instabilities

NASA Astrophysics Data System (ADS)

Rouhnia, Mohamad; Strom, Kyle

2015-09-01

We experimentally examine sedimentation from a freshwater suspension of clay flocs overlying saltwater in the presence of gravitational instabilities. The study seeks to determine: (1) if flocculation hampers or alters interface instability formation; (2) how the removal rates of sediment from the buoyant layer compare to those predicted by individual floc settling; and (3) whether or not it is possible to develop a model for effective settling velocity. The experiments were conducted in a tank at isothermal conditions. All experiments were initially stably stratified but later developed instabilities near the interface that grew into downward convecting plumes of fluid and sediment. Throughout, we measured sediment concentration in the upper and lower layers, floc size, and plume descent rates. The data showed that flocculation modifies the mixture settling velocity, and therefore shifts the mode of interface instability from double-diffusive (what one would expect from unflocculated clay) to settling-driven leaking and Rayleigh-Taylor instability formation. Removal rates of sediment from the upper layer in the presence of these instabilities were on the same order of magnitude as those predicted by individual floc settling. However, removal rates were found to better correlate with the speed of the interface plumes. A simple force-balance model was found to be capable of reasonably describing plume velocity based on concentration in the buoyant layer. This relation, coupled with a critical Grashof number and geometry relations, allowed us to develop a model for the effective settling velocity of the mixture based solely on integral values of the upper layer.

Effect of temperature on compact layer of Pt electrode in PEMFCs by first-principles molecular dynamics calculations

NASA Astrophysics Data System (ADS)

He, Yang; Chen, Changfeng; Yu, Haobo; Lu, Guiwu

2017-01-01

Formation of the double-layer electric field and capacitance of the water-metal interface is of significant interest in physicochemical processes. In this study, we perform first- principles molecular dynamics simulations on the water/Pt(111) interface to investigate the temperature dependence of the compact layer electric field and capacitance based on the calculated charge densities. On the Pt (111) surface, water molecules form ice-like structures that exhibit more disorder along the height direction with increasing temperature. The Osbnd H bonds of more water molecules point toward the Pt surface to form Ptsbnd H covalent bonds with increasing temperature, which weaken the corresponding Osbnd H bonds. In addition, our calculated capacitance at 300 K is 15.2 mF/cm2, which is in good agreement with the experimental results. As the temperature increases from 10 to 450 K, the field strength and capacitance of the compact layer on Pt (111) first increase and then decrease slightly, which is significant for understanding the water/Pt interface from atomic level.

Production of Exocytic Vesicular Antigens by Primary Liver Cell Cultures

DTIC Science & Technology

1990-05-08

cells should be plated over the basement membrane proteins, and for optimal results, a second layer of protein should be precipitated over the cells...culture as two layer (two gelatin coated nylon sheets stapled together) and single layer carriers seeded with cells (Table 2). From the performance results...summarized in table 2, it can be seen that double sheets of 2% gelatin: 6% glutaraldehyde (carrier II) made the best carriers. A double layer of

Application of double-layered skin phantoms for optical flow imaging during laser tattoo treatments

NASA Astrophysics Data System (ADS)

Lee, Byeong-il; Song, Woosub; Kim, Hyejin; Kang, Hyun Wook

2016-05-01

The feasible application of double-layered skin phantoms was evaluated to identify artificial blood flow with a Doppler optical coherence tomography (DOCT) system for laser tattoo treatments. Polydimethylsiloxane (PDMS) was used to fabricate the artificial phantoms with flow channels embedded. A double-integrating sphere system with an inverse adding-doubling method quantified both the absorption and the reduced scattering coefficients for epidermis and dermis phantoms. Both OCT and caliper measurements confirmed the double-layered phantom structure (epidermis = 136 ± 17 µm vs. dermis = 3.0 ± 0.1 mm). The DOCT method demonstrated that high flow rates were associated with high image contrast, visualizing the position and the shape of the flow channel. Application of the channel-embedded skin phantoms in conjunction with DOCT can be a reliable technique to assess dynamic variations in the blood flow during and after laser tattoo treatments.

Teaching the Double Layer.

ERIC Educational Resources Information Center

Bockris, J. O'M.

1983-01-01

Suggests various methods for teaching the double layer in electrochemistry courses. Topics addressed include measuring change in absolute potential difference (PD) at interphase, conventional electrode potential scale, analyzing absolute PD, metal-metal and overlap electron PDs, accumulation of material at interphase, thermodynamics of electrified…

Anti-Fouling Double-Skinned Forward Osmosis Membrane with Zwitterionic Brush for Oily Wastewater Treatment.

PubMed

Ong, Chi Siang; Al-Anzi, Bader; Lau, Woei Jye; Goh, Pei Sean; Lai, Gwo Sung; Ismail, Ahmad Fauzi; Ong, Yue Seong

2017-07-31

Despite its attractive features for energy saving separation, the performance of forward osmosis (FO) has been restricted by internal concentration polarization and fast fouling propensity that occur in the membrane sublayer. These problems have significantly affected the membrane performance when treating highly contaminated oily wastewater. In this study, a novel double-skinned FO membrane with excellent anti-fouling properties has been developed for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between a highly dense polyamide (PA) layer for salt rejection and a fairly loose dense bottom zwitterionic layer for emulsified oil particle removal. The top dense PA layer was synthesized via interfacial polymerization meanwhile the bottom layer was made up of a zwitterionic polyelectrolyte brush - (poly(3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone), abbreviated as PMAPS layer. The resultant double-skinned membrane exhibited a high water flux of 13.7 ± 0.3 L/m 2 .h and reverse salt transport of 1.6 ± 0.2 g/m 2 .h under FO mode using 2 M NaCl as the draw solution and emulsified oily solution as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation.

Enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target

NASA Astrophysics Data System (ADS)

Ji, Yanling; Duan, Tao; Zhou, Weimin; Li, Boyuan; Wu, Fengjuan; Zhang, Zhimeng; Ye, Bin; Wang, Rong; Wu, Chunrong; Tang, Yongjian

2018-02-01

An enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target is investigated using two-dimensional particle-in-cell simulations. The target consists of a cone attached to a double-layer hollow channel with a near-critical-density inner layer. The periodic electron beams are generated by the combination of ponderomotive force and longitudinal laser electric field. Then a stable electron propagation is achieved in the double-layer channel over a much longer distance without evident divergency, compared with a normal cone-channel target. Detailed simulations show that the much better long-distance collimation and guidance of energetic electrons is attributed to the much stronger electromagnetic fields at the inner wall surfaces. Furthermore, a continuous electron acceleration is obtained by the more intense laser electric fields and extended electron acceleration length in the channel. Our investigation shows that by employing this advanced target, both the forward-going electron energy flux in the channel and the energy coupling efficiency from laser to electrons are about threefold increased in comparison with the normal case.

Significance of the double-layer capacitor effect in polar rubbery dielectrics and exceptionally stable low-voltage high transconductance organic transistors.

PubMed

Wang, Chao; Lee, Wen-Ya; Kong, Desheng; Pfattner, Raphael; Schweicher, Guillaume; Nakajima, Reina; Lu, Chien; Mei, Jianguo; Lee, Tae Hoon; Wu, Hung-Chin; Lopez, Jeffery; Diao, Ying; Gu, Xiaodan; Himmelberger, Scott; Niu, Weijun; Matthews, James R; He, Mingqian; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

2015-12-14

Both high gain and transconductance at low operating voltages are essential for practical applications of organic field-effect transistors (OFETs). Here, we describe the significance of the double-layer capacitance effect in polar rubbery dielectrics, even when present in a very low ion concentration and conductivity. We observed that this effect can greatly enhance the OFET transconductance when driven at low voltages. Specifically, when the polar elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) was used as the dielectric layer, despite a thickness of several micrometers, we obtained a transconductance per channel width 30 times higher than that measured for the same organic semiconductors fabricated on a semicrystalline PVDF-HFP with a similar thickness. After a series of detailed experimental investigations, we attribute the above observation to the double-layer capacitance effect, even though the ionic conductivity is as low as 10(-10) S/cm. Different from previously reported OFETs with double-layer capacitance effects, our devices showed unprecedented high bias-stress stability in air and even in water.

Significance of the double-layer capacitor effect in polar rubbery dielectrics and exceptionally stable low-voltage high transconductance organic transistors

PubMed Central

Wang, Chao; Lee, Wen-Ya; Kong, Desheng; Pfattner, Raphael; Schweicher, Guillaume; Nakajima, Reina; Lu, Chien; Mei, Jianguo; Lee, Tae Hoon; Wu, Hung-Chin; Lopez, Jeffery; Diao, Ying; Gu, Xiaodan; Himmelberger, Scott; Niu, Weijun; Matthews, James R.; He, Mingqian; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

2015-01-01

Both high gain and transconductance at low operating voltages are essential for practical applications of organic field-effect transistors (OFETs). Here, we describe the significance of the double-layer capacitance effect in polar rubbery dielectrics, even when present in a very low ion concentration and conductivity. We observed that this effect can greatly enhance the OFET transconductance when driven at low voltages. Specifically, when the polar elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) was used as the dielectric layer, despite a thickness of several micrometers, we obtained a transconductance per channel width 30 times higher than that measured for the same organic semiconductors fabricated on a semicrystalline PVDF-HFP with a similar thickness. After a series of detailed experimental investigations, we attribute the above observation to the double-layer capacitance effect, even though the ionic conductivity is as low as 10–10 S/cm. Different from previously reported OFETs with double-layer capacitance effects, our devices showed unprecedented high bias-stress stability in air and even in water. PMID:26658331

Effects of Acoustic Modulation and Mixed Fuel on Flame Synthesis of Carbon Nanomaterials in an Atmospheric Environment

PubMed Central

Hu, Wei-Chieh; Sari, Shanti Kartika; Hou, Shuhn-Shyurng; Lin, Ta-Hui

2016-01-01

In this study, methane–ethylene jet diffusion flames modulated by acoustic excitation in an atmospheric environment were used to investigate the effects of acoustic excitation frequency and mixed fuel on nanomaterial formation. Acoustic output power was maintained at a constant value of 10 W, while the acoustic excitation frequency was varied (f = 0–90 Hz). The results show that the flame could not be stabilized on the port when the ethylene volume concentration (ΩE) was less than 40% at f = 10 Hz, or when ΩE = 0% (i.e., pure methane) at f = 90 Hz. The reason for this is that the flame had a low intensity and was extinguished by the entrained air due to acoustic modulation. Without acoustic excitation (f = 0 Hz), the flame was comprised of a single-layer structure for all values of ΩE, and almost no carbon nanomaterials were synthesized. However, with acoustic excitation, a double-layer flame structure was generated for frequencies close to both the natural flickering frequency and the acoustically resonant frequency. This double-layer flame structure provided a favorable flame environment for the fabrication of carbon nanomaterials. Consequently, the synthesis of carbon nano-onions was significantly enhanced by acoustic excitation near both the natural flickering frequency and the acoustically resonant frequency. At f = 20 Hz (near the natural flickering frequency) for 0% ≤ ΩE ≤ 100%, a quantity of carbon nano-onions (CNOs) piled like bunches of grapes was obtained as a result of improved mixing of the fuel with ambient air. High-density CNOs were also produced at f = 70 Hz (close to the acoustically resonant frequency) for 40% ≤ ΩE ≤ 100%. Furthermore, carbon nanotubes (CNTs) were synthesized only at 80 Hz for ΩE = 0%. The suitable temperature range for the synthesis of CNTs was slightly higher than that for the formation of CNOs (about 600 °C for CNTs; 510–600 °C for CNOs). PMID:28774059

Accelerating dewetting on deformable substrates by adding a liquid underlayer.

PubMed

Xu, Lin; Reiter, Günter; Shi, Tongfei; An, Lijia

2010-05-18

We investigated the dependence of the dewetting velocity of a thin, low-viscosity polystyrene (PS) top film on a poly(methyl methacrylate) (PMMA) double layer consisting of a low-viscosity underlayer of thickness h(L) coated with a high-viscosity middle layer of thickness h(M). The addition of the liquid underlayer generated complex nonmonotonic behavior of the dewetting velocity as a function of increasing h(M). In particular, we observed an acceleration of dewetting for an intermediate range of h(M). This phenomenon has been interpreted by a combination deformation of the middle elastic layer and a concurrent change in the contact angle. On one hand, deformation led to the formation of a trench that dissipated energy during its movement through the liquid underlayer and thus caused a slowing down of dewetting. However, with an increase in the thickness of the elastic middle layer, the size of the trench decreased and its influence on the dewetting velocity also decreased. On the other hand, the deformation of the elastic layer also led to an increase in the contact angle. This increase in the driving capillary forces caused an increase in the dewetting velocity.

Ca/Alq3 hybrid cathode buffer layer for the optimization of organic solar cells based on a planar heterojunction

NASA Astrophysics Data System (ADS)

El Jouad, Z.; Barkat, L.; Stephant, N.; Cattin, L.; Hamzaoui, N.; Khelil, A.; Ghamnia, M.; Addou, M.; Morsli, M.; Béchu, S.; Cabanetos, C.; Richard-Plouet, M.; Blanchard, P.; Bernède, J. C.

2016-11-01

Use of efficient anode cathode buffer layer (CBL) is crucial to improve the efficiency of organic photovoltaic cells. Here we show that using a double CBL, Ca/Alq3, allows improving significantly cell performances. The insertion of Ca layer facilitates electron harvesting and blocks hole collection, leading to improved charge selectivity and reduced leakage current, whereas Alq3 blocks excitons. After optimisation of this Ca/Alq3 CBL using CuPc as electron donor, it is shown that it is also efficient when SubPc is substituted to CuPc in the cells. In that case we show that the morphology of the SubPc layer, and therefore the efficiency of the cells, strongly depends on the deposition rate of the SubPc film. It is necessary to deposit slowly (0.02 nm/s) the SubPc films because at higher deposition rate (0.06 nm/s) the films are porous, which induces leakage currents and deterioration of the cell performances. The SubPc layers whose formations are kinetically driven at low deposition rates are more uniform, whereas those deposited faster exhibit high densities of pinholes.

Design and measure of a tunable double-band metamaterial absorber in the THz spectrum

NASA Astrophysics Data System (ADS)

Guiming, Han

2018-04-01

We demonstrate and measure a hybrid double-band tunable metamaterial absorber in the terahertz region. The measured metamaterial absorber contains of a hybrid dielectric layer structure: a SU-8 layer and a VO2 layer. Near perfect double-band absorption performances are achieved by optimizing the SU-8 layer thickness at room temperature 25 °C. Measured results show that the phase transition can be observed when the measured temperature reaches 68 °C. Further measured results indicate that the resonance frequency and absorption amplitude of the proposed metamaterial absorber are tunable through increasing the measured temperature, while structural parameters unchanged. The proposed hybrid metamaterial absorber shows many advantages, such as frequency agility, absorption amplitude tunable, and simple fabrication.

Outdoor flocking of quadcopter drones with decentralized model predictive control.

PubMed

Yuan, Quan; Zhan, Jingyuan; Li, Xiang

2017-11-01

In this paper, we present a multi-drone system featured with a decentralized model predictive control (DMPC) flocking algorithm. The drones gather localized information from neighbors and update their velocities using the DMPC flocking algorithm. In the multi-drone system, data packages are transmitted through XBee ® wireless modules in broadcast mode, yielding such an anonymous and decentralized system where all the calculations and controls are completed on an onboard minicomputer of each drone. Each drone is a double-layered agent system with the coordination layer running multi-drone flocking algorithms and the flight control layer navigating the drone, and the final formation of the flock relies on both the communication range and the desired inter-drone distance. We give both numerical simulations and field tests with a flock of five drones, showing that the DMPC flocking algorithm performs well on the presented multi-drone system in both the convergence rate and the ability of tracking a desired path. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Conventional En Masse Repair Versus Separate Double-Layer Double-Row Repair for the Treatment of Delaminated Rotator Cuff Tears.

PubMed

Kim, Yang-Soo; Lee, Hyo-Jin; Jin, Hong-Ki; Kim, Sung-Eun; Lee, Jin-Woo

2016-05-01

The rotator cuff tendon is known to exert a shear force between the superficial and deep layers. Owing to this characteristic, separate repair of delaminated rotator cuff tears has been introduced for the restoration of the physiological biomechanics of the rotator cuff. However, whether conventional en masse repair or separate repair is superior is controversial in terms of outcomes. To compare clinical outcomes between conventional en masse repair and separate double-layer double-row repair for the treatment of delaminated rotator cuff tears. Randomized controlled study; Level of evidence, 2. Between August 2007 and March 2014, a total of 82 patients who underwent arthroscopic rotator cuff repair of a delaminated tear were enrolled and randomized into 2 groups. In group 1 (n = 48), arthroscopic conventional en masse repair was performed. In group 2 (n = 34), separate double-layer double-row repair was performed. The American Shoulder and Elbow Surgeons score, Constant score, Simple Shoulder Test score, and visual analog scale (VAS) score for pain and range of motion (ROM) were assessed before surgery; at 3, 6, and 12 months after surgery; and at the last follow-up visit. Magnetic resonance imaging (MRI) was performed at 12 months postoperatively to examine the retear rate and pattern. There was no significant difference between groups in the preoperative demographic data, including patient age, sex, symptom duration, tear size, and functional scores (P > .05). The mean follow-up period was 25.9 ± 1.2 months. Significant improvements in functional and pain scores were observed in both groups at the last follow-up visit. However, no significant differences in functional scores and ROM were found between the 2 groups at each time point, except that group 2 had significantly lower VAS pain scores (P < .05) at 3, 6, and 12 months postoperatively. Eight (17%) of 48 patients in group 1 and 6 (18%) of 34 patients in group 2 showed retears on MRI at 12-month follow-up (P > .05). Both conventional en masse repair and separate double-layer double-row repair were effective in improving clinical outcomes in the treatment of delaminated rotator cuff tears. Lower pain scores were seen in patients who underwent separate double-layer double-row repair. © 2016 The Author(s).

Use of Shape Memory Alloys in the Robust Control of Smart Structures

DTIC Science & Technology

1993-08-01

OHP (anions) @ Cation II I I JU Anion O0HP(cations) 0 Ano Cation electrf statically h eld in double layer 0 ’ Double Diff sion Bulk Layer L., Layer I...Effect in Thermoelastic In-Tl Martensite, Mem . Fac. Eng. Kyoto Univ., 43(2): 287-303 (1981) 43. A. Nagasawa, Memory Effect in In-Tl Alloy, J. Phys. Soc

Cyclic loading of rotator cuff reconstructions: single-row repair with modified suture configurations versus double-row repair.

PubMed

Lorbach, Olaf; Bachelier, Felix; Vees, Jochen; Kohn, Dieter; Pape, Dietrich

2008-08-01

Double-row repair is suggested to have superior biomechanical properties in rotator cuff reconstruction compared with single-row repair. However, double-row rotator cuff repair is frequently compared with simple suture repair and not with modified suture configurations. Single-row rotator cuff repairs with modified suture configurations have similar failure loads and gap formations as double-row reconstructions. Controlled laboratory study. We created 1 x 2-cm defects in 48 porcine infraspinatus tendons. Reconstructions were then performed with 4 single-row repairs and 2 double-row repairs. The single-row repairs included transosseous simple sutures; double-loaded corkscrew anchors in either a double mattress or modified Mason-Allen suture repair; and the Magnum Knotless Fixation Implant with an inclined mattress. Double-row repairs were either with Bio-Corkscrew FT using modified Mason-Allen stitches or a combination of Bio-Corkscrew FT and PushLock anchors using the SutureBridge Technique. During cyclic load (10 N to 60-200 N), gap formation was measured, and finally, ultimate load to failure and type of failure were recorded. Double-row double-corkscrew anchor fixation had the highest ultimate tensile strength (398 +/- 98 N) compared to simple sutures (105 +/- 21 N; P < .0001), single-row corkscrews using a modified Mason-Allen stitch (256 +/- 73 N; P = .003) or double mattress repair (290 +/- 56 N; P = .043), the Magnum Implant (163 +/- 13 N; P < .0001), and double-row repair with PushLock and Bio-Corkscrew FT anchors (163 +/- 59 N; P < .0001). Single-row double mattress repair was superior to transosseous sutures (P < .0001), the Magnum Implant (P = .009), and double-row repair with PushLock and Bio-Corkscrew FT anchors (P = .009). Lowest gap formation was found for double-row double-corkscrew repair (3.1 +/- 0.1 mm) compared to simple sutures (8.7 +/- 0.2 mm; P < .0001), the Magnum Implant (6.2 +/- 2.2 mm; P = .002), double-row repair with PushLock and Bio-Corkscrew FT anchors (5.9 +/- 0.9 mm; P = .008), and corkscrews with modified Mason-Allen sutures (6.4 +/- 1.3 mm; P = .001). Double-row double-corkscrew anchor rotator cuff repair offered the highest failure load and smallest gap formation and provided the most secure fixation of all tested configurations. Double-loaded suture anchors using modified suture configurations achieved superior results in failure load and gap formation compared to simple suture repair and showed similar loads and gap formation with double-row repair using PushLock and Bio-Corkscrew FT anchors. Single-row repair with modified suture configurations may lead to results comparable to several double-row fixations. If double-row repair is used, modified stitches might further minimize gap formation and increase failure load.

Effects of channel thickness on oxide thin film transistor with double-stacked channel layer

NASA Astrophysics Data System (ADS)

Lee, Kimoon; Kim, Yong-Hoon; Yoon, Sung-Min; Kim, Jiwan; Oh, Min Suk

2017-11-01

To improve the field effect mobility and control the threshold voltage ( V th ) of oxide thin film transistors (TFTs), we fabricated the oxide TFTs with double-stacked channel layers which consist of thick Zn-Sn-O (ZTO) and very thin In-Zn-O (IZO) layers. We investigated the effects of the thickness of thin conductive layer and the conductivity of thick layer on oxide TFTs with doublestacked channel layer. When we changed the thickness of thin conductive IZO channel layer, the resistivity values were changed. This resistivity of thin channel layer affected on the saturation field effect mobility and the off current of TFTs. In case of the thick ZTO channel layer which was deposited by sputtering in Ar: O2 = 10: 1, the device showed better performances than that which was deposited in Ar: O2 = 1: 1. Our TFTs showed high mobility ( μ FE ) of 40.7 cm2/Vs and V th of 4.3 V. We assumed that high mobility and the controlled V th were caused by thin conductive IZO layer and thick stable ZTO layer. Therefore, this double-stacked channel structure can be very promising way to improve the electrical characteristics of various oxide thin film transistors.

Preparation of pH-Responsive Hollow Capsules via Layer-by-Layer Assembly of Exfoliated Layered Double Hydroxide Nanosheets and Polyelectrolytes.

PubMed

Katagiri, Kiyofumi; Shishijima, Yoshinori; Koumoto, Kunihito; Inumaru, Kei

2018-01-01

pH-Responsive smart capsules were developed by the layer-by-layer assembly with a colloidtemplating technique. Polystyrene (PS) particles were employed as core templates. Acid-soluble inorganic nanosheets were prepared from Mg-Al layered double hydroxide (LDH) by an exfoliation technique. LDH nanosheets and anionic polyelectrolytes were alternatively deposited on PS core particles by the layer-by-layer assembly using electrostatic interaction. Hollow capsules were obtained by the removal of the PS core particles. The hollow capsules obtained thus were collapsed at acidic conditions by dissolution of LDH nanosheets in the hollow shells. The dissolution rate, i.e., the responsiveness of capsule, is tunable according to the strength of acids.

Fabrication of highly hydrophilic filter using natural and hydrothermally treated mica nanoparticles for efficient waste oil-water separation.

PubMed

Gunatilake, Udara Bimendra; Bandara, Jayasundera

2017-04-15

For the effective oil/water separation, a novel superhydrophilic (underwater superoleophobic) filter is fabricated with the naturally and hydrothermally treated mica particles. To fabricate a double layered filter, hydrothermally treated mica particles were initially electrodeposited on a stainless steel mesh and a natural mica particles were sprayed on the first hydrothermally deposited mica layer. The double layered mica coated membrane showed superamphiphilic and superhydrophilic/superoleophobic (contact angle >159°) characteristics in air and underwater respectively. The membrane can separate range of oil-water mixtures with oil/water separation efficiency over ∼99%. Properties of double layered mica membrane were investigated and noted that the surface adhesion properties of mica is enhanced by the hydrothermal treatment of mica and the higher roughness of the mica layer is maintained by the natural mica. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interface reconstruction with emerging charge ordering in hexagonal manganite

PubMed Central

Xu, Changsong; Han, Myung-Geun; Bao, Shanyong; Nan, Cewen; Bellaiche, Laurent

2018-01-01

Multiferroic materials, which simultaneously have multiple orderings, hold promise for use in the next generation of memory devices. We report a novel self-assembled MnO double layer forming at the interface between a multiferroic YMnO3 film and a c-Al2O3 substrate. The crystal structures and the valence states of this MnO double layer were studied by atomically resolved scanning transmission electron microscopy and spectroscopy, as well as density functional theory (DFT) calculations. A new type of charge ordering has been identified within this MnO layer, which also contributes to a polarization along the [001] direction. DFT calculations further establish the occurrence of multiple couplings between charge and lattice in this novel double layer, in addition to the polarization in nearby YMnO3 single layer. The interface reconstruction reported here creates a new playground for emergent physics, such as giant ferroelectricity and strong magnetoelectric coupling, in manganite systems. PMID:29795782

Effect of magnetron sputtering parameters and stress state of W film precursors on WSe2 layer texture by rapid selenization.

PubMed

Li, Hongchao; Gao, Di; Xie, Senlin; Zou, Jianpeng

2016-11-04

Tungsten diselenide (WSe 2 ) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe 2 film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe 2 growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe 2 film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe 2 films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe 2 film texture. Based on the stress state of the W film, a model for growth of the WSe 2 films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe 2 film.

Effect of magnetron sputtering parameters and stress state of W film precursors on WSe2 layer texture by rapid selenization

PubMed Central

Li, Hongchao; Gao, Di; Xie, Senlin; Zou, Jianpeng

2016-01-01

Tungsten diselenide (WSe2) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe2 film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe2 growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe2 film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe2 films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe2 film texture. Based on the stress state of the W film, a model for growth of the WSe2 films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe2 film. PMID:27812031

Low Temperature Double-layer Capacitors with Improved Energy Density: An Overview of Recent Development Efforts

NASA Technical Reports Server (NTRS)

Brandon, Erik J.; West, William C.; Smart, Marshall C.; Korenblit, Yair; Kajdos, Adam; Kvit, Alexander; Jagiello, Jacek; Yushin, Gleb

2012-01-01

Electrochemical double-layer capacitors are finding increased use in a wide range of energy storage applications, particularly where high pulse power capabilities are required. Double-layer capacitors store charge at a liquid/solid interface, making them ideal for low temperature power applications, due to the facile kinetic processes associated with the rearrangement of the electrochemical double-layer at these temperatures. Potential low temperature applications include hybrid and electric vehicles, operations in polar regions, high altitude aircraft and aerospace avionics, and distributed environmental and structural health monitoring. State-of-the-art capacitors can typically operate to -40 C, with a subsequent degradation in power performance below room temperature. However, recent efforts focused on advanced electrolyte and electrode systems can enable operation to temperatures as low as -70 C, with capacities similar to room temperature values accompanied by reasonably low equivalent series resistances. This presentation will provide an overview of recent development efforts to extend and improve the wide temperature performance of these devices.

Streaming potential generated by a pressure-driven flow over a super-hydrophobic surface

NASA Astrophysics Data System (ADS)

Zhao, Hui

2010-11-01

The streaming potential generated by a pressured-driven flow over a weakly charged striped slip-stick surface (the zeta potential of the surface is smaller than the thermal potential (25 mV) with an arbitrary double layer thickness is theoretically studied by solving the Poisson-Boltzmann equation and Stokes equation. A series solution of the streaming potential is derived. Approximate expressions for the streaming potential in the limits of thin double layers and thick double layers are also presented, in excellent agreement with the full solution. The streaming potential is compared against that over a homogenously charged smooth surface. Our results indicate that the streaming potential over a super-hydrophobic surface only can be enhanced when the liquid-gas interface is charged. In addition, as the double layer thickness increases, the advantage of the super-hydrophobic surface diminishes. The impact of a slip-stick surface on the streaming potential might provide guidance for designing novel and efficient microfludic energy conversion devices using a super-hydrophobic surface.

Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

NASA Technical Reports Server (NTRS)

Smith, Robert A.

1987-01-01

The evolution and long-time stability of a double layer (DL) in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double layer potential structure. A simple model is presented in which this current redistribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double layer potential. The flank charging may be represented as that of a nonlinear transmission line. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a one-dimensional simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

NASA Technical Reports Server (NTRS)

Smith, Robert A.

1987-01-01

The evolution and long-time stability of a double layer in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double-layer potential structure. A simple model is presented in which this current re-distribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double-layer potential. The flank charging may be represented as that of a nonlinear transmission. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a 1-d simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

An S3-3 search for confined regions of large parallel electric fields

NASA Astrophysics Data System (ADS)

Boehm, M. H.; Mozer, F. S.

1981-06-01

S3-3 satellite passes through several hundred perpendicular shocks are searched for evidence of large, mostly parallel electric fields (several hundred millivolts per meter, total potential of several kilo-volts) in the auroral zone magnetosphere at altitudes of several thousand kilometers. The actual search criteria are that one or more E-field data points have a parallel component E sub z greater than 350 mV/m in general, or 100 mV/m for data within 10 seconds of a perpendicular shock, since double layers might be likely, in such regions. Only a few marginally convincing examples of the electric fields are found, none of which fits a double layer model well. From statistics done with the most unbiased part of the data set, upper limits are obtained on the number and size of double layers occurring in the auroral zone magnetosphere, and it is concluded that the double layers most probably cannot be responsible for the production of diffuse aurora or inverted-V events.

Chemical treatment of wastewater from flue gas desulphurisation

NASA Astrophysics Data System (ADS)

Pasiecznik, Iwona; Szczepaniak, Włodzimierz

2017-11-01

The article presents results of laboratory tests of removing boron and arsenium from non-ideal solutions using double-layered magnesium/aluminium hydroxides (Mg/Al Double-Layered Hydroxide - DLH) produced with nitrate-chloride method. In research, wastewater from an installation for flue gas desulfurization was examined. Double-layered hydroxides are perfect absorbents for anionic compounds. The research proved high effectiveness of preparation with reference to arsenium, as well as confirmed the effect of presence of sulfatic and arsenate ions on the effectiveness of boron removal. On the basis of research on absorption kinetics a theoretical dose of DLH/NO3-Cl/M preparation was calculated and compared with a dose that ensures emimination of boron below the limit standarized by the national regulations. Application of double-layered magnesium/aluminium hydroxides for boron elimination from industrial wastewater requires significantly higher doses of preparation than those calculated in model investigations. It is due to the priority of removal of multivalent ions, such as sulfatic, arsenate or phosphate ions, by DLH/NO3-Cl/M.

The electric double layer at a metal electrode in pure water

NASA Astrophysics Data System (ADS)

Brüesch, Peter; Christen, Thomas

2004-03-01

Pure water is a weak electrolyte that dissociates into hydronium ions and hydroxide ions. In contact with a charged electrode a double layer forms for which neither experimental nor theoretical studies exist, in contrast to electrolytes containing extrinsic ions like acids, bases, and solute salts. Starting from a self-consistent solution of the one-dimensional modified Poisson-Boltzmann equation, which takes into account activity coefficients of point-like ions, we explore the properties of the electric double layer by successive incorporation of various correction terms like finite ion size, polarization, image charge, and field dissociation. We also discuss the effect of the usual approximation of an average potential as required for the one-dimensional Poisson-Boltzmann equation, and conclude that the one-dimensional approximation underestimates the ion density. We calculate the electric potential, the ion distributions, the pH-values, the ion-size corrected activity coefficients, and the dissociation constants close to the electric double layer and compare the results for the various model corrections.

Allogeneic cultured keratinocytes vs. cadaveric skin to cover wide-mesh autogenous split-thickness skin grafts.

PubMed

Monstrey, S; Beele, H; Kettler, M; Van Landuyt, K; Blondeel, P; Matton, G; Naeyaert, J M

1999-09-01

Improved shock therapy has extended the limits of survival in patients with massive burns, and nowadays skin coverage has become the major problem in burn management. The use of mesh skin grafts is still the simplest technique to expand the amount of available donor skin. However, very wide-mesh skin grafts take a very long time to heal, often resulting in unaesthetic scar formation. On the other hand, allogeneic cultured keratinocytes have been reported as a natural source of growth factors and thus could be useful to improve wound healing of these wide-mesh grafts. A clinical study was performed to compare the use of cryopreserved allogeneic cultured keratinocytes vs. the traditional cadaveric skin as a double layer over widely expanded autogenous skin grafts. This procedure was performed in 18 pairs of full-thickness burn wounds (with similar depth and location) in 11 severely burned patients. Early clinical evaluation was made at 2, 3, and 4 to 5 weeks. Parameters such as epithelialization, granulation tissue formation, infection, and scar formation were evaluated. Biopsies were taken to compare the histological characteristics of the epidermis, the epidermal-dermal junction, and the dermis. Late evaluations were performed at 6 and 12 months regarding color, softness, thickness, and subjective feeling of the scar tissue. Aside from a faster (p < 0.05) epithelialization in the keratinocyte group at 2 weeks, there were no statistically different results in any of the early evaluated parameters, neither clinically nor histologically. At long-term follow-up, clinical results and scar characteristics were not significantly different in the two compared groups. It is concluded from the results of this study that, during the early phase, epithelialization was faster with allogeneic cultured keratinocytes compared with cadaveric skin. However, taking into account the substantial difference in costs, the described use of cryopreserved allogeneic cultured keratinocytes as a double layer on meshed autogenous split-thickness skin grafts can hardly be advocated.

Aluminium substitution in iron(II-III)-layered double hydroxides: Formation and cationic order

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

Ruby, Christian; Abdelmoula, Mustapha; Aissa, Rabha

The formation and the modifications of the structural properties of an aluminium-substituted iron(II-III)-layered double hydroxide (LDH) of formula Fe{sub 4}{sup II}Fe{sub (2-6y)}{sup III}Al{sub 6y}{sup III} (OH){sub 12} SO{sub 4}, 8H{sub 2}O are followed by pH titration curves, Moessbauer spectroscopy and high-resolution X-ray powder diffraction using synchrotron radiation. Rietveld refinements allow to build a structural model for hydroxysulphate green rust, GR(SO{sub 4}{sup 2-}), i.e. y=0, in which a bilayer of sulphate anions points to the Fe{sup 3+} species. A cationic order is proposed to occur in both GR(SO{sub 4}{sup 2-}) and aluminium-substituted hydroxysulphate green rust when y<0.08. Variation of the cellmore » parameters and a sharp decrease in average crystal size and anisotropy are detected for an aluminium content as low as y=0.01. The formation of Al-GR(SO{sub 4}{sup 2-}) is preceded by the successive precipitation of Fe{sup III} and Al{sup III} (oxy)hydroxides. Adsorption of more soluble Al{sup III} species onto the initially formed ferric oxyhydroxide may be responsible for this slowdown of crystal growth. Therefore, the insertion of low aluminium amount (y{approx}0.01) could be an interesting way for increasing the surface reactivity of iron(II-III) LDH that maintains constant the quantity of the reactive Fe{sup II} species of the material. - Graphical abstract: (a) Crystallographical structure of sulphated green rust: SO{sub 4}{sup 2-} point to the Fe{sup 3+} cations (red) that form an ordered array with the Fe{sup 2+} cations (green). (b) Width and asymmetry of the synchrotron XRD peaks increase rapidly when some Al{sup 3+} species substitute the Fe{sup 3+} cations; z is molar ratio Al{sup 3+}/Fe{sup 3+}.« less

Periodical plasma structures controlled by external magnetic field

NASA Astrophysics Data System (ADS)

Schweigert, I. V.; Keidar, M.

2017-06-01

The characteristics of two-dimensional periodical structures in a magnetized plasma are studied using kinetic simulations. Ridges (i.e. spikes in electron and ion density) are formed and became more pronounced with an increase of magnetic field incidence angle in the plasma volume in the cylindrical chamber. These ridges are shifted relative to each other, which results in the formation of a two-dimensional double-layer structure. Depending on Larmor radius and Debye length up to 19 potential steps appear across the oblique magnetic field. The electrical current gathered into the channels is associated with the electron and ion density ridges.

Electrical conduction in 100 keV Kr+ ion implanted poly (ethylene terephthalate)

NASA Astrophysics Data System (ADS)

Goyal, P. K.; Kumar, V.; Gupta, Renu; Mahendia, S.; Anita, Kumar, S.

2012-06-01

Polyethylene terephthalate (PET) samples have been implanted to 100 keV Kr+ ions at the fluences 1×1015-- 1×1016 cm-2. From I-V characteristics, the conduction mechanism was found to be shifted from ohmic to space charge limited conduction (SCLC) after implantation. The surface conductivity of these implanted samples was found to increase with increasing implantation dose. The structural alterations in the Raman spectra of implanted PET samples indicate that such an increase in the conductivity may be attributed to the formation of conjugated double bonded carbonaceous structure in the implanted layer of PET.

Membrane formation in liquids by adding an antagonistic salt

NASA Astrophysics Data System (ADS)

Sadakane, Koichiro; Seto, Hideki

2018-03-01

Antagonistic salts are composed of hydrophilic and hydrophobic ions. In a binary mixture, such as water and organic solvent, these ion pairs preferentially dissolve to those phases, respectively, and there is a coupling between the charge density and the composition. The heterogeneous distribution of ions forms a large electric double layer at the interface between these solvents. This reduces the interfacial tension between water and organic solvent, and stabilizes an ordered structure, such as a membrane. These phenomena have been extensively studied from both theoretical and experimental point of view. In addition, the numerical simulations can reproduce such ordered structures.

Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

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

Andersson, Joakim; Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore; Ni, Pavel

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

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

Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

Improved Low Temperature Performance of Supercapacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J.; West, William C.; Smart, Marshall C.; Gnanaraj, Joe

2013-01-01

Low temperature double-layer capacitor operation enabled by: - Base acetonitrile / TEATFB salt formulation - Addition of low melting point formates, esters and cyclic ethers center dot Key electrolyte design factors: - Volume of co-solvent - Concentration of salt center dot Capacity increased through higher capacity electrodes: - Zeolite templated carbons - Asymmetric cell designs center dot Continuing efforts - Improve asymmetric cell performance at low temperature - Cycle life testing Motivation center dot Benchmark performance of commercial cells center dot Approaches for designing low temperature systems - Symmetric cells (activated carbon electrodes) - Symmetric cells (zeolite templated carbon electrodes) - Asymmetric cells (lithium titanate/activated carbon electrodes) center dot Experimental results center dot Summary

Auroral-particle precipitation and trapping caused by electrostatic double layers in the ionosphere.

PubMed

Albert, R D; Lindstrom, P J

1970-12-25

Interpretation of high-resolution angular distribution measurements of the primary auroral electron flux detected by a rocket probe launched into a visible aurora from Fort Churchill in the fall of 1966 leads to the following conclusions. The auroral electron flux is nearly monoenergetic and has a quasi-trapped as well as a precipitating component. The quasi-trapped flux appears to be limited to a region defined by magnetic-mirror points and multiple electrostatic double layers in the ionosphere. The electrostatic field of the double-layer distribution enhances the aurora by lowering the magnetic-mirror points and supplying energy to the primary auroral electrons.

Morphologies, Preparations and Applications of Layered Double Hydroxide Micro-/Nanostructures

PubMed Central

Kuang, Ye; Zhao, Lina; Zhang, Shuai; Zhang, Fazhi; Dong, Mingdong; Xu, Sailong

2010-01-01

Layered double hydroxides (LDHs), also well-known as hydrotalcite-like layered clays, have been widely investigated in the fields of catalysts and catalyst support, anion exchanger, electrical and optical functional materials, flame retardants and nanoadditives. This feature article focuses on the progress in micro-/nanostructured LDHs in terms of morphology, and also on the preparations, applications, and perspectives of the LDHs with different morphologies. PMID:28883378

Frequency Characteristics of the MAGLEV Double-layered Propulsion Coil

NASA Astrophysics Data System (ADS)

Ema, Satoshi

The MAGLEV (magnetically levitated vehicle) is now well along in development testing at Yamanashi Test Line. The MAGLEV power source needs to supply a variable voltage and variable frequency to propulsion coils, which installed on outdoor guideway. The output voltage of the electric power converter contains many higher harmonics, which causes many troubles such as inductive interference. Accordingly, it is necessary to clarify the frequency characteristics of the propulsion coils and the power feeding circuit. In view of this situation, experiments and the theoretical analysis concerning the frequency characteristics of the propulsion coils with single-layer arrangement and the power feeding circuit at Miyazaki Test Line had been performed by the author. But the arrangement of the propulsion coils had been changed in Yamanashi Test Line from the single-layered coils to the double-layered coils for the stability of the super-conducting magnet on board. Thus, experiments and investigations concerning the frequency characteristics(resonance characteristics)of the propulsion coils with double-layer arrangement at Yamanashi Test Line have been performed but a theoretical analysis had not been done enough. A theoretical analysis was therefore done in this paper by applying the inverted L equivalent circuit with mutual inductance and capacitance to the propulsion coil, from which the positive and zero phase characteristics of the double-layered propulsion coils were analyzed.

The double capsules in macro-textured breast implants.

PubMed

Giot, Jean-Philippe; Paek, Laurence S; Nizard, Nathanael; El-Diwany, Mostafa; Gaboury, Louis A; Nelea, Monica; Bou-Merhi, Joseph S; Harris, Patrick G; Danino, Michel A

2015-10-01

Breast implants are amongst the most widely used types of permanent implants in modern medicine and have both aesthetic and reconstructive applications with excellent biocompatibility. The double capsule is a complication associated with textured prostheses that leads to implant displacement; however, its etiology has yet to be elucidated. In this study, 10 double capsules were sampled from breast expander implants for in-depth analysis; histologically, the inner capsular layer demonstrated highly organized collagen in sheets with delamination of fibers. At the prosthesis interface (PI) where the implant shell contacts the inner capsular layer, scanning electron microscopy (SEM) revealed a thin layer which mirrored the three-dimensional characteristics of the implant texture; the external surface of the inner capsular layer facing the intercapsular space (ICS) was flat. SEM examination of the inner capsule layer revealed both a large bacterial presence as well as biofilm deposition at the PI; a significantly lower quantity of bacteria and biofilm were found at the ICS interface. These findings suggest that the double capsule phenomenon's etiopathogenesis is of mechanical origin. Delamination of the periprosthetic capsule leads to the creation of the ICS; the maintained separation of the 2 layers subsequently alters the biostability of the macro-textured breast implant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biomechanical evaluation of knotless anatomical double-layer double-row rotator cuff repair: a comparative ex vivo study.

PubMed

Hepp, Pierre; Osterhoff, Georg; Engel, Thomas; Marquass, Bastian; Klink, Thomas; Josten, Christoph

2009-07-01

The layered configuration of the rotator cuff tendon is not taken into account in classic rotator cuff tendon repair techniques. The mechanical properties of (1) the classic double-row technique, (2) a double-layer double-row (DLDR) technique in simple suture configuration, and (3) a DLDR technique in mattress suture configuration are significantly different. Controlled laboratory study. Twenty-four sheep shoulders were assigned to 3 repair groups of full-thickness infraspinatus tears: group 1, traditional double-row repair; group 2, DLDR anchor repair with simple suture configuration; and group 3, DLDR knotless repair with mattress suture configuration. After ultrasound evaluation of the repair, each specimen was cyclically loaded with 10 to 100 N for 50 cycles. Each specimen was then loaded to failure at a rate of 1 mm/s. There were no statistically significant differences among the 3 testing groups for the mean footprint area. The cyclic loading test revealed no significant difference among the 3 groups with regard to elongation. For the load-to-failure test, groups 2 and 3 showed no differences in ultimate tensile load when compared with group 1. However, when compared to group 2, group 3 was found to have significantly higher values regarding ultimate load, ultimate elongation, and energy absorbed. The DLDR fixation techniques may provide strength of initial repair comparable with that of commonly used double-row techniques. When compared with the knotless technique with mattress sutures, simple suture configuration of DLDR repair may be too weak. Knotless DLDR rotator cuff repair may (1) restore the footprint by the use of double-row principles and (2) enable restoration of the shape and profile. Double-layer double-row fixation in mattress suture configuration has initial fixation strength comparable with that of the classic double-row fixation and so may potentially improve functional results of rotator cuff repair.

Cu2+ ions as a paramagnetic probe to study the surface chemical modification process of layered double hydroxides and hydroxide salts with nitrate and carboxylate anions.

PubMed

Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; Wypych, Fernando

2008-04-01

A layered zinc hydroxide nitrate (Zn5(OH)8(NO3)2.2H2O) and a layered double hydroxide (Zn/Al-NO3) were synthesized by coprecipitation and doped with different amounts of Cu2+ (0.2, 1, and 10 mol%), as paramagnetic probe. Although the literature reports that the nitrate ion is free (with D3h symmetry) between the layers of these two structures, the FTIR spectra of two zinc hydroxide nitrate samples show the C2v symmetry for the nitrate ion, whereas the g ||/A || value in the EPR spectra of Cu2+ is high. This fact suggests bonding of some nitrate ions to the layers of the zinc hydroxide nitrate. The zinc hydroxide nitrate was used as matrix in the intercalation reaction with benzoate, o-chlorobenzoate, and o-iodobenzoate ions. FTIR spectra confirm the ionic exchange reaction and the EPR spectroscopy reveals bonding of the organic ions to the inorganic layers of the zinc hydroxide nitrate, while the layered double hydroxides show only exchange reactions.

Fe(II) sorption on pyrophyllite: Effect of structural Fe(III) (impurity) in pyrophyllite on nature of layered double hydroxide (LDH) secondary mineral formation

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

Starcher, Autumn N.; Li, Wei; Kukkadapu, Ravi K.

Fe(II)-Al(III)-LDH (layered double hydroxide) phases have been shown to form from reactions of aqueous Fe(II) with Fe-free Al-bearing minerals (phyllosilicate/clays and Al-oxides). To our knowledge, the effect of small amounts of structural Fe(III) impurities in “neutral” clays on such reactions, however, were not studied. In this study to understand the role of structural Fe(III) impurity in clays, laboratory batch studies with pyrophyllite (10 g/L), an Al-bearing phyllosilicate, containing small amounts of structural Fe(III) impurities and 0.8 mM and 3 mM Fe(II) (both natural and enriched in 57Fe) were carried out at pH 7.5 under anaerobic conditions (4% H2 – 96%more » N2 atmosphere). Samples were taken up to 4 weeks for analysis by Fe-X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy. In addition to the precipitation of Fe(II)-Al(III)-LDH phases as observed in earlier studies with pure minerals (no Fe(III) impurities in the minerals), the analyses indicated formation of small amounts of Fe(III) containing solid(s), most probably hybrid a Fe(II)-Al(III)/Fe(III)-LDH phase. The mechanism of Fe(II) oxidation was not apparent but most likely was due to interfacial electron transfer from the sorbed Fe(II) to the structural Fe(III) and/or surface-sorption-induced electron-transfer from the sorbed Fe(II) to the clay lattice. Increase in the Fe(II)/Al ratio of the LDH with reaction time further indicated the complex nature of the samples. This research provides evidence for the formation of both Fe(II)-Al(III)-LDH and Fe(II)-Fe(III)/Al(III)-LDH-like phases during reactions of Fe(II) in systems that mimic the natural environments. Better understanding Fe phase formation in complex laboratory studies will improve models of natural redox systems.« less

Delivery of doxorubicin and paclitaxel from double-layered microparticles: The effects of layer thickness and dual-drug vs. single-drug loading.

PubMed

Lee, Wei Li; Guo, Wei Mei; Ho, Vincent H B; Saha, Amitaksha; Chong, Han Chung; Tan, Nguan Soon; Tan, Ern Yu; Loo, Say Chye Joachim

2015-11-01

Double-layered microparticles composed of poly(d,l-lactic-co-glycolic acid, 50:50) (PLGA) and poly(l-lactic acid) (PLLA) were loaded with doxorubicin HCl (DOX) and paclitaxel (PCTX) through a solvent evaporation technique. DOX was localized in the PLGA shell, while PCTX was localized in the PLLA core. The aim of this study was to investigate how altering layer thickness of dual-drug, double-layered microparticles can influence drug release kinetics and their antitumor capabilities, and against single-drug microparticles. PCTX-loaded double-layered microparticles with denser shells retarded the initial release of PCTX, as compared with dual-drug-loaded microparticles. The DOX release from both DOX-loaded and dual-drug-loaded microparticles were observed to be similar with an initial burst. Through specific tailoring of layer thicknesses, a suppressed initial burst of DOX and a sustained co-delivery of two drugs can be achieved over 2months. Viability studies using spheroids of MCF-7 cells showed that controlled co-delivery of PCTX and DOX from dual-drug-loaded double-layered microparticles were better in reducing spheroid growth rate. This study provides mechanistic insights into how by tuning the layer thickness of double-layered microparticles the release kinetics of two drugs can be controlled, and how co-delivery can potentially achieve better anticancer effects. While the release of multiple drugs has been reported to achieve successful apoptosis and minimize drug resistance, most conventional particulate systems can only deliver a single drug at a time. Recently, although a number of formulations (e.g. micellar nanoparticles, liposomes) have been successful in delivering two or more anticancer agents, sustained co-delivery of these agents remains inadequate due to the complex agent loading processes and rapid release of hydrophilic agents. Therefore, the present work reports the multilayered particulate system that simultaneously hosts different drugs, while being able to tune their individual release over months. We believe that our findings would be of interest to the readers of Acta Biomaterialia because the proposed system could open a new avenue on how two drugs can be released, through rate-controlling carriers, for combination chemotherapy. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Electrofluidic gating of a chemically reactive surface.

PubMed

Jiang, Zhijun; Stein, Derek

2010-06-01

We consider the influence of an electric field applied normal to the electric double layer at a chemically reactive surface. Our goal is to elucidate how surface chemistry affects the potential for field-effect control over micro- and nanofluidic systems, which we call electrofluidic gating. The charging of a metal-oxide-electrolyte (MOE) capacitor is first modeled analytically. We apply the Poisson-Boltzmann description of the double layer and impose chemical equilibrium between the ionizable surface groups and the solution at the solid-liquid interface. The chemically reactive surface is predicted to behave as a buffer, regulating the charge in the double layer by either protonating or deprotonating in response to the applied field. We present the dependence of the charge density and the electrochemical potential of the double layer on the applied field, the density, and the dissociation constants of ionizable surface groups and the ionic strength and the pH of the electrolyte. We simulate the responses of SiO(2) and Al(2)O(3), two widely used oxide insulators with different surface chemistries. We also consider the limits to electrofluidic gating imposed by the nonlinear behavior of the double layer and the dielectric strength of oxide materials, which were measured for SiO(2) and Al(2)O(3) films in MOE configurations. Our results clarify the response of chemically reactive surfaces to applied fields, which is crucial to understanding electrofluidic effects in real devices.

Observation of the effects of stronger magnetic fields on warm, higher energy electrons and ion beams transiting a double layer in a helicon plasma

NASA Astrophysics Data System (ADS)

Scharer, John; Sung, Yung-Ta; Li, Yan

2017-10-01

Fast, two-temperature electrons (>80 eV, Te =13 eV tail, 4 eV bulk) with substantial tail density fractions are created at low (< = 1.7 mtorr) Ar pressure @ 340 G in the antenna region with nozzle mirror ratio of 1.4 on MadHeX @ 900W. These distributions including a fast tail are observed upstream of a double layer. The fast, untrapped tail electrons measured downstream of the double layer have a higher temperature of 13 eV than the trapped, upstream electrons of 4 eV temperature. Upstream plasma potential fluctuations of + - 30 percent are observed. An RF-compensated Langmuir probe is used to measure the electron temperatures and densities and OES, mm wave IF and an RPA for the IEDF are also utilized. As the magnetic field is increased to 1020 G, an increase in the electron temperature and density upstream of the double layer is observed with Te= 15-25 eV with a primarily single temperature mode. Accelerated ion beam energies in the range of 65-120 eV are observed as the magnetic field is increased from 340 to 850 G. The role of the nozzle, plasma double layer and helicon wave coupling on the EEDF and ion acceleration will be discussed. Research supported in part by the University of Wisconsin.

First-principles density functional theory (DFT) study of gold nanorod and its interaction with alkanethiol ligands.

PubMed

Hu, Hang; Reven, Linda; Rey, Alejandro

2013-10-17

The structure and mechanical properties of gold nanorods and their interactions with alkenthiolate self-assembled monolayers have been determined using a novel first-principle density functional theory simulation approach. The multifaceted, 1-dimensional, octagonal nanorod has alternate Au100 and Au110 surfaces. The structural optimization of the gold nanorods was performed with a mixed basis: the outermost layer of gold atoms used double-ζ plus polarization (DZP), the layer below used double-ζ (DZ), and the inner layers used single-ζ (SZ). The final structure compares favorably with simulations using DZP for all atoms. Phonon dispersion calculations and ab initio molecular dynamics (AIMD) were used to establish the dynamic and thermal stability of the system. From the AIMD simulations it was found that the nanorod system will undergo significant surface reconstruction at 300 K. In addition, when subjected to mechanical stress in the axial direction, the nanorod responds as an orthotropic material, with uniform expansion along the radial direction. The Young's moduli are 207 kbar in the axial direction and 631 kbar in the radial direction. The binding of alkanethiolates, ranging from methanethiol to pentanethiol, caused formation of surface point defects on the Au110 surfaces. On the Au100 surfaces, the defects occurred in the inner layer, creating a small surface island. These defects make positive and negative concavities on the gold nanorod surface, which helps the ligand to achieve a more stable state. The simulation results narrowed significant knowledge gaps on the alkanethiolate adsorption process and on their mutual interactions on gold nanorods. The mechanical characterization offers a new dimension to understand the physical chemistry of these complex nanoparticles.

Continuous manufacturing and analytical characterization of fixed-dose, multilayer orodispersible films.

PubMed

Thabet, Yasmin; Lunter, Dominique; Breitkreutz, Joerg

2018-05-30

Various drug therapies require more than one active pharmaceutical ingredient (API) for an effective treatment. There are many advantages, e.g. to improve the compliance or pharmacodynamic response in comparison to a monotherapy or to increase the therapy safety. Until now, there are only a few products available for the paediatric population due to the lack of age appropriate dosage forms or studies proving the efficacy and safety of these products. This study aims to develop orodispersible films (ODFs) in a continuous solvent casting process as child appropriate dosage form containing both enalapril maleate (EM) and hydrochlorothiazide (HCT) separated in different film layers. Furthermore, they should be characterised and the API migration analysed by confocal Raman microscopy (CRM). ODFs were successfully produced in a continuous manufacturing process in form of double- and triple-layer formulations based on hydroxypropylcellulose (HPC) or a combination of HPC and polyvinyl alcohol (PVA). CRM revealed that both APIs migrate within the film layers shortly after manufacturing. PVA inhibits the migration inside the double-layer film, but is not able to prevent the API migration as an interlayer inside a triple-layer ODF. With increasing film layers, the content of residual solvents and the disintegration time increases (mono-layer films: <10 s, triple-layer films: 37 s). In conclusion, it was feasible to produce fixed-dose combinations in therapeutic doses up to 9 mg HCT and 3.5 mg EM for the double-layer film with adequate mechanical properties, which enable coiling up onto jumbo rolls directly after production. The best separation of the two APIs was achieved by casting a double-layer ODF consisting of different film forming polymers, which can be beneficial when processing two incompatible APIs. Copyright © 2018 Elsevier B.V. All rights reserved.

Magnetic properties and crystal texture of Co alloy thin films prepared on double bias Cr

NASA Astrophysics Data System (ADS)

Deng, Y.; Lambeth, D. N.; Lee, L.-L.; Laughlin, D. E.

1993-05-01

A double layer Cr film structure has been prepared by sputter depositing Cr on single crystal Si substrates first without substrate bias and then with various substrate bias voltages. Without substrate bias, Cr{200} texture grows on Si at room temperature; thus the first Cr layer acts like a seed Cr layer with the {200} texture, and the second Cr layer, prepared with substrate bias, tends to replicate the {200} texture epitaxially. CoCrTa and CoNiCr films prepared on these double Cr underlayers, therefore, tend to have a {112¯0} texture with their c-axes oriented in the plane of the film. At the same time, the bias sputtering of the second Cr layer increases the coercivity of the subsequently deposited magnetic films significantly. Comparison studies of δM curves show that the use of the double Cr underlayers reduces the intergranular exchange interactions. The films prepared on the Si substrates have been compared with the films prepared on canasite and glass substrates. It has also been found that the magnetic properties are similar for films on canasite and on glass.

Double-atomic layer of Tl on Si(111): Atomic arrangement and electronic properties

NASA Astrophysics Data System (ADS)

Mihalyuk, Alexey N.; Bondarenko, Leonid V.; Tupchaya, Alexandra Y.; Gruznev, Dimitry V.; Chou, Jyh-Pin; Hsing, Cheng-Rong; Wei, Ching-Ming; Zotov, Andrey V.; Saranin, Alexander A.

2018-02-01

Metastable double-atomic layer of Tl on Si(111) has recently been found to display interesting electric properties, namely superconductivity below 0.96 K and magnetic-field-induced transition into an insulating phase intermediated by a quantum metal state. In the present work, using a set of experimental techniques, including low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoelectron spectroscopy, in a combination with density-functional-theory calculations, we have characterized atomic and electronic properties of the Tl double layer on Si(111). The double Tl layer has been concluded to contain ∼ 2.4 monolayer of Tl. A top Tl layer has a '1 × 1' basic structure and displays 6 × 6 moiré pattern which originates from various residence sites of Tl atoms. Upon cooling below ∼ 140 K, the 6 × 6 moiré pattern changes to that having a 6√{ 3} × 6√{ 3} periodicity. However, the experimentally determined electron band dispersions show a 1 × 1 periodicity. The calculated band structure unfolded into the 1 × 1 surface Brillouin zone reproduces well the main features of the photoelectron spectra.

Theoretical Study of Monolayer and Double-Layer Waveguide Love Wave Sensors for Achieving High Sensitivity.

PubMed

Li, Shuangming; Wan, Ying; Fan, Chunhai; Su, Yan

2017-03-22

Love wave sensors have been widely used for sensing applications. In this work, we introduce the theoretical analysis of the monolayer and double-layer waveguide Love wave sensors. The velocity, particle displacement and energy distribution of Love waves were analyzed. Using the variations of the energy repartition, the sensitivity coefficients of Love wave sensors were calculated. To achieve a higher sensitivity coefficient, a thin gold layer was added as the second waveguide on top of the silicon dioxide (SiO₂) waveguide-based, 36 degree-rotated, Y-cut, X-propagating lithium tantalate (36° YX LiTaO₃) Love wave sensor. The Love wave velocity was significantly reduced by the added gold layer, and the flow of wave energy into the waveguide layer from the substrate was enhanced. By using the double-layer structure, almost a 72-fold enhancement in the sensitivity coefficient was achieved compared to the monolayer structure. Additionally, the thickness of the SiO₂ layer was also reduced with the application of the gold layer, resulting in easier device fabrication. This study allows for the possibility of designing and realizing robust Love wave sensors with high sensitivity and a low limit of detection.

Multiple and configurable optical logic systems based on layered double hydroxides and chromophore assemblies.

PubMed

Shi, Wenying; Fu, Yi; Li, Zhixiong; Wei, Min

2015-01-14

Multiple and configurable fluorescence logic gates were fabricated via self-assembly of layered double hydroxides and various chromophores. These logic gates were operated by observation of different emissions with the same excitation wavelength, which achieve YES, NOT, AND, INH and INHIBIT logic operations, respectively.

Double layers without current

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

Perkins, F.W.; Sun, Y.C.

1980-11-01

The steady-state solution of the nonlinear Vlasov-Poisson equations is reduced to a nonlinear eigenvalue problem for the case of double-layer (potential drop) boundary conditions. Solutions with no relative electron-ion drifts are found. The kinetic stability is discussed. Suggestions for creating these states in experiments and computer simulations are offered.

Progress in MOSFET double-layer metalization

NASA Technical Reports Server (NTRS)

Gassaway, J. D.; Trotter, J. D.; Wade, T. E.

1980-01-01

Report describes one-year research effort in VLSL fabrication. Four activities are described: theoretical study of two-dimensional diffusion in SOS (silicon-on-sapphire); setup of sputtering system, furnaces, and photolithography equipment; experiments on double layer metal; and investigation of two-dimensional modeling of MOSFET's (metal-oxide-semiconductor field-effect transistors).

Multi-layered nanocomposite dielectrics for high density organic memory devices

NASA Astrophysics Data System (ADS)

Kang, Moonyeong; Chung, Kyungwha; Baeg, Kang-Jun; Kim, Dong Ha; Kim, Choongik

2015-01-01

We fabricated organic memory devices with metal-pentacene-insulator-silicon structure which contain double dielectric layers comprising 3D pattern of Au nanoparticles (Au NPs) and block copolymer (PS-b-P2VP). The role of Au NPs is to charge/discharge carriers upon applied voltage, while block copolymer helps to form highly ordered Au NP patterns in the dielectric layer. Double-layered nanocomposite dielectrics enhanced the charge trap density (i.e., trapped charge per unit area) by Au NPs, resulting in increase of the memory window (ΔVth).

Erosion Performance of Gadolinium Zirconate-Based Thermal Barrier Coatings Processed by Suspension Plasma Spray

NASA Astrophysics Data System (ADS)

Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per; Vaßen, Robert

2017-01-01

7-8 wt.% Yttria-stabilized zirconia (YSZ) is the standard thermal barrier coating (TBC) material used by the gas turbines industry due to its excellent thermal and thermo-mechanical properties up to 1200 °C. The need for improvement in gas turbine efficiency has led to an increase in the turbine inlet gas temperature. However, above 1200 °C, YSZ has issues such as poor sintering resistance, poor phase stability and susceptibility to calcium magnesium alumino silicates (CMAS) degradation. Gadolinium zirconate (GZ) is considered as one of the promising top coat candidates for TBC applications at high temperatures (>1200 °C) due to its low thermal conductivity, good sintering resistance and CMAS attack resistance. Single-layer 8YSZ, double-layer GZ/YSZ and triple-layer GZdense/GZ/YSZ TBCs were deposited by suspension plasma spray (SPS) process. Microstructural analysis was carried out by scanning electron microscopy (SEM). A columnar microstructure was observed in the single-, double- and triple-layer TBCs. Phase analysis of the as-sprayed TBCs was carried out using XRD (x-ray diffraction) where a tetragonal prime phase of zirconia in the single-layer YSZ TBC and a cubic defect fluorite phase of GZ in the double and triple-layer TBCs was observed. Porosity measurements of the as-sprayed TBCs were made by water intrusion method and image analysis method. The as-sprayed GZ-based multi-layered TBCs were subjected to erosion test at room temperature, and their erosion resistance was compared with single-layer 8YSZ. It was shown that the erosion resistance of 8YSZ single-layer TBC was higher than GZ-based multi-layered TBCs. Among the multi-layered TBCs, triple-layer TBC was slightly better than double layer in terms of erosion resistance. The eroded TBCs were cold-mounted and analyzed by SEM.

Effect of Al gate on the electrical behaviour of Al-doped Ta2O5 stacks

NASA Astrophysics Data System (ADS)

Skeparovski, A.; Novkovski, N.; Atanassova, E.; Paskaleva, A.; Lazarov, V. K.

2011-06-01

The electrical behaviour of Al-doped Ta2O5 films on nitrided silicon and implemented in Al-gated MIS capacitors has been studied. The dopant was introduced into the Ta2O5 through its surface by deposing a thin Al layer on the top of Ta2O5 followed by an annealing process. The HRTEM images reveal that the initial double-layer structure of the stacks composed of doped Ta2O5 and interfacial SiON layer undergoes changes during the formation of the Al gate and transforms into a three-layer structure with an additional layer between the Al electrode and the doped Ta2O5. This layer, being a result of reaction between the Al gate and the Al-doped Ta2O5, affects the overall electrical properties of the stacks. Strong charge trapping/detrapping processes have been established in the vicinity of the doped Ta2O5/SiON interface resulting in a large C-V hysteresis effect. The charge trapping also influences the current conduction in the layers keeping the current density level rather low even at high electric fields (J < 10-6 A cm-2 at 7 MV cm-1). By employing a three-layer model of the stack, the permittivity of both, the Al-doped Ta2O5 and the additional layer, has been estimated and the corresponding conduction mechanisms identified.

Low-bandgap double-heterostructure InAsP/GaInAs photovoltaic converters

DOEpatents

Wanlass, Mark W.

2001-01-01

A low-bandgap, double-heterostructure PV device is provided, including in optical alignment a first InP.sub.1-y As.sub.y n-layer formed with an n-type dopant, an Ga.sub.x In.sub.1-x As absorber layer, the absorber layer having an n-region formed with an n-type dopant and an p-region formed with a p-type dopant to form a single pn-junction, and a second InP.sub.1-y As.sub.y p-layer formed with a p-type dopant, wherein the first and second layers are used for passivation and minority carrier confinement of the absorber layers.

Synthesis, characterization and application of two-dimensional layered metal hydroxides for environmental remediation purposes

NASA Astrophysics Data System (ADS)

Machingauta, Cleopas

Two-dimensional layered nano composites, which include layered double hydroxides (LDHs), hydroxy double salts (HDSs) and layered hydroxide salts (LHSs) are able to intercalate different molecular species within their gallery space. These materials have a tunable structural composition which has made them applicable as fire retardants, adsorbents, catalysts, catalyst support materials, and ion exchangers. Thermal treatment of these materials results in destruction of the layers and formation of mixed metal oxides (MMOs) and spinels. MMOs have the ability to adsorb anions from solution and may also regenerate layered structures through a phenomenon known as memory effect. Zinc-nickel hydroxy nitrate was used for the uptake of a series of halogenated acetates (HAs). HAs are pollutants introduced into water systems as by-products of water chlorination and pesticide degradation; their sequestration from water is thus crucial. Optimization of layered materials for controlled uptake requires an understanding of their ion-exchange kinetics and thermodynamics. Exchange kinetics of these anions was monitored using ex-situ PXRD, UV-vis, HPLC and FTIR. It was revealed that exchange rates and uptake efficiencies are related to electronic spatial extents and the charge on carboxyl-oxygen atoms. In addition, acetate and nitrate-based HDSs were used to explore how altering the hydroxide layer affects uptake of acetate/nitrate ions. Changing the metal identities affects the interaction of the anions with the layers. From FTIR, we observed that nitrates coordinate in a D3h and Cs/C 2v symmetry; the nitrates in D3h symmetry were easily exchangeable. Interlayer hydrogen bonding was also revealed to be dependent on metal identity. Substituting divalent cations with trivalent cations produces materials with a higher charge density than HDSs and LHSs. A comparison of the uptake efficiency of zinc-aluminum, zinc-gallium and zinc-nickel hydroxy nitrates was performed using trichloroacetic acid as target anion. Uptake efficiency was better for LDHs than HDS, and between the LDHs, zinc-aluminum hydroxy nitrate was the best material for the uptake of tClAc. Calcined LDHs were applied for the uptake of methyl-orange, model azo-dye. The ability to regenerate the layered structures was helpful for improving adsorption efficiency. It has been reveal that calcined LDHs are also better adsorbents than calcined HDSs.

Solution NMR structure of CsgE: Structural insights into a chaperone and regulator protein important for functional amyloid formation.

PubMed

Shu, Qin; Krezel, Andrzej M; Cusumano, Zachary T; Pinkner, Jerome S; Klein, Roger; Hultgren, Scott J; Frieden, Carl

2016-06-28

Curli, consisting primarily of major structural subunit CsgA, are functional amyloids produced on the surface of Escherichia coli, as well as many other enteric bacteria, and are involved in cell colonization and biofilm formation. CsgE is a periplasmic accessory protein that plays a crucial role in curli biogenesis. CsgE binds to both CsgA and the nonameric pore protein CsgG. The CsgG-CsgE complex is the curli secretion channel and is essential for the formation of the curli fibril in vivo. To better understand the role of CsgE in curli formation, we have determined the solution NMR structure of a double mutant of CsgE (W48A/F79A) that appears to be similar to the wild-type (WT) protein in overall structure and function but does not form mixed oligomers at NMR concentrations similar to the WT. The well-converged structure of this mutant has a core scaffold composed of a layer of two α-helices and a layer of three-stranded antiparallel β-sheet with flexible N and C termini. The structure of CsgE fits well into the cryoelectron microscopy density map of the CsgG-CsgE complex. We highlight a striking feature of the electrostatic potential surface in CsgE structure and present an assembly model of the CsgG-CsgE complex. We suggest a structural mechanism of the interaction between CsgE and CsgA. Understanding curli formation can provide the information necessary to develop treatments and therapeutic agents for biofilm-related infections and may benefit the prevention and treatment of amyloid diseases. CsgE could establish a paradigm for the regulation of amyloidogenesis because of its unique role in curli formation.

Supersonically Spray-Coated Colloidal Quantum Dot Ink Solar Cells

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

Choi, Hyekyoung; Lee, Jong-Gun; Mai, Xuan Dung

Controlling the thickness of quantum dot (QD) films is difficult using existing film formation techniques, which employ pre-ligand-exchanged PbS QD inks, because of several issues: 1) poor colloidal stability, 2) use of high-boiling-point solvents for QD dispersion, and 3) limitations associated with one-step deposition. Here in this paper, we suggest a new protocol for QD film deposition using electrical double-layered PbS QD inks, prepared by solution-phase ligand exchange using methyl ammonium lead iodide (MAPbI 3). The films are deposited by the supersonic spraying technique, which facilitates the rapid evaporation of the solvent and the subsequent deposition of the PbS QDmore » ink without requiring a post-deposition annealing treatment for solvent removal. The film thickness could be readily controlled by varying the number of spraying sweeps made across the substrate. This spray deposition process yields high-quality n-type QD films quickly (within 1 min) while minimizing the amount of the PbS QD ink used to less than 5 mg for one device (300-nm-thick absorbing layer, 2.5 x 2.5 cm 2). Further, the formation of an additional p-layer by treatment with mercaptopropionic acid allows for facile hole extraction from the QD films, resulting in a power conversion efficiency of 3.7% under 1.5 AM illumination.« less

Supersonically Spray-Coated Colloidal Quantum Dot Ink Solar Cells

DOE PAGES

Choi, Hyekyoung; Lee, Jong-Gun; Mai, Xuan Dung; ...

2017-04-04

Controlling the thickness of quantum dot (QD) films is difficult using existing film formation techniques, which employ pre-ligand-exchanged PbS QD inks, because of several issues: 1) poor colloidal stability, 2) use of high-boiling-point solvents for QD dispersion, and 3) limitations associated with one-step deposition. Here in this paper, we suggest a new protocol for QD film deposition using electrical double-layered PbS QD inks, prepared by solution-phase ligand exchange using methyl ammonium lead iodide (MAPbI 3). The films are deposited by the supersonic spraying technique, which facilitates the rapid evaporation of the solvent and the subsequent deposition of the PbS QDmore » ink without requiring a post-deposition annealing treatment for solvent removal. The film thickness could be readily controlled by varying the number of spraying sweeps made across the substrate. This spray deposition process yields high-quality n-type QD films quickly (within 1 min) while minimizing the amount of the PbS QD ink used to less than 5 mg for one device (300-nm-thick absorbing layer, 2.5 x 2.5 cm 2). Further, the formation of an additional p-layer by treatment with mercaptopropionic acid allows for facile hole extraction from the QD films, resulting in a power conversion efficiency of 3.7% under 1.5 AM illumination.« less

Anionic surfactant enhanced phosphate desorption from Mg/Al-layered double hydroxides by micelle formation.

PubMed

Shimamura, Akihiro; Jones, Mark I; Metson, James B

2013-12-01

Desorption of interlayer hydrogen phosphate (HPO4) from hydrogen phosphate intercalated Mg/Al-layered double hydroxide (LDH-HPO4) by anion exchange with surfactant anions has been investigated under controlled conditions. Three types of surfactant, Dodecylbenzenesulphonate (DBS), Dodecylsulphate (DS) and 1-Octanesulphonate (OS), anions were used for intercalation experiments over a range of concentrations, and for all solutions, it was shown that the desorption of hydrogen phosphate is enhanced at concentrations close to the critical micelle concentration (CMC). Intercalation of the surfactant anions into LDH-HPO4 was confirmed by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning electron microscopy (SEM). More than 90% removal of the hydrogen phosphate was achieved at CMC. Repeat adsorption tests to investigate recyclability showed that desorption with 0.005 M DBS improved subsequent phosphate re-adsorption, allowing around 90% of the original adsorption over three cycles. This is much higher than when desorption was conducted using either Na2CO3 or NaCl-NaOH solutions, even at much higher concentrations. This study suggests potential economic and environmental advantages in using these surfactants in improving the cycling performance of LDH materials as absorbents for clean-up of water systems. Copyright © 2013 Elsevier Inc. All rights reserved.

LAM-1 and FAT Genes Control Development of the Leaf Blade in Nicotiana sylvestris.

PubMed Central

McHale, NA

1993-01-01

Leaf primordia of the lam-1 mutant of Nicotiana sylvestris grow normally in length but remain bladeless throughout development. The blade initiation site is established at the normal time and position in lam-1 primordia. Anticlinal divisions proceed normally in the outer L1 and L2 layers, but the inner L3 cells fail to establish the periclinal divisions that normally generate the middle mesophyll core. The lam-1 mutation also blocks formation of blade mesophyll from distal L2 cells. This suggests that LAM-1 controls a common step in initiation of blade tissue from the L2 and L3 lineage of the primordium. Another recessive mutation (fat) was isolated in N. sylvestris that induces abnormal periclinal divisions in the mesophyll during blade initiation and expansion. This generates a blade approximately twice its normal thickness by doubling the number of mesophyll cell layers from four to approximately eight. Presumably, the fat mutation defines a negative regulator involved in repression of periclinal divisions in the blade. The lam-1 fat double mutant shows radial proliferation of mesophyll cells at the blade initiation site. This produces a highly disorganized, club-shaped blade that appears to represent an additive effect of the lam-1 and fat mutations on blade founder cells. PMID:12271096

Synthesis of protocatechuic acid-zinc/aluminium-layered double hydroxide nanocomposite as an anticancer nanodelivery system

NASA Astrophysics Data System (ADS)

Barahuie, Farahnaz; Hussein, Mohd Zobir; Gani, Shafinaz Abd; Fakurazi, Sharida; Zainal, Zulkarnain

2015-01-01

Protocatechuic acid, an active anticancer agent, has been intercalated into Zn/Al-layered double hydroxide at Zn/Al=2) using two different preparation methods, co-precipitation and ion-exchange, which are labelled as PZAE and PZAC, respectively. The release of protocatechuate from the nanocomposites occurred in a controlled manner and was fitted satisfactorily to pseudo-second order kinetics. The basal spacing of the resulting nanocomposites PZAE and PZAC was 10.2 and 11.0 Å, respectively, indicating successful intercalation of protocatechuate anions into the interlayer galleries of Zn/Al-NO3-LDH in a monolayer arrangement with angles of 24 and 33° from the z-axis in PZAE and PZAC, respectively. The formation of nanocomposites was further confirmed by a Fourier transform infrared study. Thermogravimetric and differential thermogravimetric analyses indicated that the thermal stability of the intercalated protocatechuic acid was significantly enhanced compared to its free protocatechuic acid, and the drug content in the nanocomposites was estimated to be approximately 32.6% in PZAE and 29.2% in PZAC. Both PZAE and PZAC nanocomposites inhibit the growth of human cervical, liver and colorectal cancer cell lines and exhibit no toxic effects towards normal fibroblast 3T3 cell after 72 h of treatment.

Intercalation of IR absorber into layered double hydroxides: Preparation, thermal stability and selective IR absorption

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

Zhu, Haifeng; Tang, Pinggui; Feng, Yongjun, E-mail: yjfeng@mail.buct.edu.cn

2012-03-15

Highlights: Black-Right-Pointing-Pointer PMIDA anions were intercalated into Mg{sub 2}Al-NO{sub 3} LDH by anion-exchange method. Black-Right-Pointing-Pointer The prepared material has highly selective IR absorption property in 9-11 {mu}m. Black-Right-Pointing-Pointer The obtained material has practical applications as heat-retaining additive. -- Abstract: N-phosphonomethyl aminodiacetic acid (PMIDA) was intercalated into the interlayer spacing of layered double hydroxides (LDH) by an anion-exchange method. The intercalated LDHs were characterized by various techniques such as powder X-ray diffraction (XRD), FT-IR spectroscopy, elemental analysis and simultaneous thermogravimetric and mass spectrometry (TG-MS) in details. The results show the formation of Mg{sub 2}Al-PMIDA LDH based on the expansion of d-spacingmore » from 0.89 nm to 1.22 nm and the disappearance of the characteristic IR absorption band at 1384 cm{sup -1} for NO{sub 3}{sup -} anions. The incorporation of Mg{sub 2}Al-PMIDA LDH into the low density polyethylene (LDPE) as an additive enhances the selectivity of IR absorption in the main wavelength region 9-11 {mu}m for radiant heat loss at night. Mg{sub 2}Al-PMIDA LDH as a heat-retaining additive has practical application in agricultural plastic films.« less

Mixed Valence Perovskite Cs2 Au2 I6 : A Potential Material for Thin-Film Pb-Free Photovoltaic Cells with Ultrahigh Efficiency.

PubMed

Debbichi, Lamjed; Lee, Songju; Cho, Hyunyoung; Rappe, Andrew M; Hong, Ki-Ha; Jang, Min Seok; Kim, Hyungjun

2018-03-01

New light is shed on the previously known perovskite material, Cs 2 Au 2 I 6 , as a potential active material for high-efficiency thin-film Pb-free photovoltaic cells. First-principles calculations demonstrate that Cs 2 Au 2 I 6 has an optimal band gap that is close to the Shockley-Queisser value. The band gap size is governed by intermediate band formation. Charge disproportionation on Au makes Cs 2 Au 2 I 6 a double-perovskite material, although it is stoichiometrically a single perovskite. In contrast to most previously discussed double perovskites, Cs 2 Au 2 I 6 has a direct-band-gap feature, and optical simulation predicts that a very thin layer of active material is sufficient to achieve a high photoconversion efficiency using a polycrystalline film layer. The already confirmed synthesizability of this material, coupled with the state-of-the-art multiscale simulations connecting from the material to the device, strongly suggests that Cs 2 Au 2 I 6 will serve as the active material in highly efficient, nontoxic, and thin-film perovskite solar cells in the very near future. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, characterization, and evaluation of simple aluminum-based adsorbents for fluoride removal from drinking water.

PubMed

Du, Junyi; Sabatini, David A; Butler, Elizabeth C

2014-04-01

Simple aluminum (hydr)oxides and layered double hydroxides were synthesized using common chemicals and equipment by varying synthesis temperature, concentrations of extra sulfate and citrate, and metal oxide amendments. Aluminum (hydr)oxide samples were aged at either 25 or 200°C during synthesis and, in some cases, calcined at 600 °C. Despite yielding increased crystallinity and mineral phase changes, higher temperatures had a generally negative effect on fluoride adsorption. Addition of extra sulfate during synthesis of aluminum (hydr)oxides led to significantly higher fluoride adsorption capacity compared to aluminum (hydr)oxides prepared with extra citrate or no extra ligands. X-ray diffraction results suggest that extra sulfate led to the formation of both pseudoboehmite (γ-AlOOH) and basaluminite (Al4SO4(OH)10⋅4H2O) at 200 °C; energy dispersive X-ray spectroscopy confirmed the presence of sulfur in this solid. Treatment of aluminum (hydr)oxides with magnesium, manganese, and iron oxides did not significantly impact fluoride adsorption. While layered double hydroxides exhibited high maximum fluoride adsorption capacities, their adsorption capacities at dissolved fluoride concentrations close to the World Health Organization drinking water guideline of 1.5 mg L(-1) were much lower than those for the aluminum (hydr)oxides. Copyright © 2013 Elsevier Ltd. All rights reserved.

Using Molecular Dynamics to quantify the electrical double layer and examine the potential for its direct observation in the in-situ TEM

DOE PAGES

Welch, David A.; Mehdi, Beata L.; Hatchell, Hanna J.; ...

2015-03-25

Understanding the fundamental processes taking place at the electrode-electrolyte interface in batteries will play a key role in the development of next generation energy storage technologies. One of the most fundamental aspects of the electrode-electrolyte interface is the electrical double layer (EDL). Given the recent development of high spatial resolution in-situ electrochemical cells for scanning transmission electron microscopy (STEM), there now exists the possibility that we can directly observe the formation and dynamics of the EDL. In this paper we predict electrolyte structure within the EDL using classical models and atomistic Molecular Dynamics (MD) simulations. The MD simulations show thatmore » the classical models fail to accurately reproduce concentration profiles that exist within the electrolyte. It is thus suggested that MD must be used in order to accurately predict STEM images of the electrode-electrolyte interface. Using MD and image simulations together for a high contrast electrolyte (the high atomic number CsCl electrolyte), it is determined that, for a smooth interface, concentration profiles within the EDL should be visible experimentally. When normal experimental parameters such as rough interfaces and low-Z electrolytes (like those used in Li-ion batteries) are considered, observation of the EDL appears to be more difficult.« less

Effects of preparation steps on the physical parameters and electromechanical properties of IPMC actuators

NASA Astrophysics Data System (ADS)

Wang, Yanjie; Zhu, Zicai; Chen, Hualing; Luo, Bin; Chang, Longfei; Wang, Yongquan; Li, Dichen

2014-12-01

The electromechanical properties of ionic polymer-metal composites (IPMC) are affected by many factors, including resistivity of surface electrodes, bending stiffness and dielectric modulus, etc, which are closely related to physical and chemical preparation steps. This paper focuses on the effects of preparation steps on these physical parameters and electromechanical properties of IPMC actuators. The mechanisms of electrode formation in the preparation steps are also clarified and investigated. To obtain samples with different features, one or more of the crucial process steps, including pretreatment, impregnation-reduction and chemical plating, were selected to fabricate IPMC. The experimental observations revealed that the physical parameters of IPMC strongly depend on their electrode morphologies caused by different steps, which were reasonable from the standpoint of physics. IPMC with the characteristics of low surface resistance and low bending stiffness, and a large area of interface electrode exhibits a perfect performance. The improvements were considered to be attributed to the double-layer electrostatic effect, induced by the broad dispersion of penetrated electrode nanoparticles. An electrical component, consisting of an equivalent circuit of a parallel combination of the serial circuit of the resistance and the electric double-layer capacitance, is introduced to qualitatively explain the deformation behaviors of IPMC. This research helps to improve the preparation steps and promote the understanding of IPMC.

Enhancing phosphate adsorption by Mg/Al layered double hydroxide functionalized biochar with different Mg/Al ratios.

PubMed

Li, Ronghua; Wang, Jim J; Zhou, Baoyue; Awasthi, Mukesh Kumar; Ali, Amjad; Zhang, Zengqiang; Gaston, Lewis A; Lahori, Altaf Hussain; Mahar, Amanullah

2016-07-15

Mg/Al ratio plays a significant role for anion adsorption by Mg/Al-layered double hydroxides (Mg/Al-LDHs) modified biochar. In this study, Mg/Al-LDHs biochar with different Mg/Al ratios (2, 3, 4) were prepared by co-precipitation for phosphate removal from aqueous solution. Factors on phosphate adsorption including Mg/Al ratio, pH, and the presence of other inorganic anions were investigated through batch experiments. Increasing Mg/Al ratio in the Mg/Al-LDHs biochar composites generally enhanced phosphate adsorption with Langmuir adsorption maximum calculated at 81.83mg phosphorous (P) per gram of 4:1Mg/Al-LDHs biochar at pH3.0. The adsorption process was best described by the pseudo-second-order kinetic model. Solution pH had greater effects on the phosphate adsorption by Mg/Al LDHs biochar composites with lower Mg/Al ratios. The presence of other inorganic anions decreased the phosphate adsorption efficiency in the order of F(-) > SO4(2-) > NO2(-) >Cl(-). Phosphate adsorption mechanism involves ion exchange, electrostatic attraction and surface inner-sphere complex formation. Overall, Mg/Al-LDHs biochar composites offer a potential alternative of carbon-based adsorbent for phosphate removal from aqueous solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Transformation of zinc hydroxide chloride monohydrate to crystalline zinc oxide.

PubMed

Moezzi, Amir; Cortie, Michael; McDonagh, Andrew

2016-04-25

Thermal decomposition of layered zinc hydroxide double salts provides an interesting alternative synthesis for particles of zinc oxide. Here, we examine the sequence of changes occurring as zinc hydroxide chloride monohydrate (Zn5(OH)8Cl2·H2O) is converted to crystalline ZnO by thermal decomposition. The specific surface area of the resultant ZnO measured by BET was 1.3 m(2) g(-1). A complicating and important factor in this process is that the thermal decomposition of zinc hydroxide chloride is also accompanied by the formation of volatile zinc-containing species under certain conditions. We show that this volatile compound is anhydrous ZnCl2 and its formation is moisture dependent. Therefore, control of atmospheric moisture is an important consideration that affects the overall efficiency of ZnO production by this process.

AC electric field induced dielectrophoretic assembly behavior of gold nanoparticles in a wide frequency range

NASA Astrophysics Data System (ADS)

Liu, Weiyu; Wang, Chunhui; Ding, Haitao; Shao, Jinyou; Ding, Yucheng

2016-05-01

In this work, we focus on frequency-dependence of pearl chain formations (PCF) of gold nanoparticles driven by AC dielectrophoresis (DEP), especially in a low field-frequency range, where induced double-layer charging effect at ideally polarizable surfaces on particle DEP behavior and surrounding liquid motion need not be negligible. As field frequency varies, grown features of DEP assembly structures ranging from low-frequency non-bridged gap to high-frequency single gold nanoparticle-made nanowires bridging the electrodes are demonstrated experimentally. Specifically, at 10 kHz, a kind of novel channel-like structure with parallel opposing banks is formed at the center of interelectrode gap. In stark contrast, at 1 MHz, thin PCF with diameter of 100 nm is created along the shortest distance of the isolation spacing. Moreover, a particular conductive path of nanoparticle chains is produced at 1 MHz in a DEP device embedded with multiple floating electrodes. A theoretical framework taking into account field-induced double-layer polarization at both the particle/electrolyte and electrode/electrolyte interface is developed to correlate these experimental observations with induced-charge electrokinetic (ICEK) phenomenon. And a RC circuit model is helpful in accounting for the formation of this particular non-bridged channel-like structure induced by a low-frequency AC voltage. As compared to thin PCF formed at high field frequency that effectively short circuits the electrode pair, though it is difficult for complete PCF bridging to occur at low frequency, the non-bridged conducting microstructure has potential to further miniaturize the size of electrode gap fabricated by standard micromachining process and may find useful application in biochemical sensing.

Double-layer interlaced nested multi-ring array metallic mesh for high-performance transparent electromagnetic interference shielding.

PubMed

Wang, Heyan; Lu, Zhengang; Liu, Yeshu; Tan, Jiubin; Ma, Limin; Lin, Shen

2017-04-15

We report a nested multi-ring array metallic mesh (NMA-MM) that shows a highly uniform diffraction pattern theoretically and experimentally. Then a high-performance transparent electromagnetic interference (EMI) shielding structure is constituted by the double-layer interlaced NMA-MMs separated by transparent quartz-glass substrate. Experimental results show that double-layer interlaced NMA-MM structure exhibits a shielding effectiveness (SE) of over 27 dB in the Ku-band, with a maximal SE of 37 dB at 12 GHz, normalized optical transmittance of 90%, and minimal image quality degradation due to the interlaced arrangement. It thus shows great potential for practical applications in transparent EMI shielding devices.

Layered double hydroxide stability. 1. Relative stabilities of layered double hydroxides and their simple counterparts

NASA Technical Reports Server (NTRS)

Boclair, J. W.; Braterman, P. S.

1999-01-01

Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant titration curves yields nominal solubility constants for the LDH. The corresponding LDH stabilities are in the order Mg < Mn < Co approximately Ni < Zn for M(II) and Al < Fe for M(III). The stability of LDH relative to the separate metal hydroxides/hydrous oxides is discussed.

Interlayer tunneling in double-layer quantum hall pseudoferromagnets.

PubMed

Balents, L; Radzihovsky, L

2001-02-26

We show that the interlayer tunneling I-V in double-layer quantum Hall states displays a rich behavior which depends on the relative magnitude of sample size, voltage length scale, current screening, disorder, and thermal lengths. For weak tunneling, we predict a negative differential conductance of a power-law shape crossing over to a sharp zero-bias peak. An in-plane magnetic field splits this zero-bias peak, leading instead to a "derivative" feature at V(B)(B(parallel)) = 2 pi Planck's over 2 pi upsilon B(parallel)d/e phi(0), which gives a direct measurement of the dispersion of the Goldstone mode corresponding to the spontaneous symmetry breaking of the double-layer Hall state.

Influence of boundary on the effect of double-layer polarization and the electrophoretic behavior of soft biocolloids.

PubMed

Yeh, Li-Hsien; Fang, Kuo-Ying; Hsu, Jyh-Ping; Tseng, Shiojenn

2011-12-01

The electrophoresis of a soft particle comprising a rigid core and a charged porous membrane layer in a narrow space is modeled. This simulates, for example, the capillary electrophoresis of biocolloids such as cells and microorganisms, and biosensor types of device. We show that, in addition to the boundary effect, the effects of double-layer polarization (DLP) and the electroosmotic retardation flow can be significant, yielding interesting electrophoretic behaviors. For example, if the friction coefficient of the membrane layer and/or the boundary is large, then the DLP effect can be offset by the electroosmotic retardation flow, making the particle mobility to decrease with increasing double layer thickness, which is qualitatively consistent with many experimental observations in the literature, but has not been explained clearly in previous analyses. In addition, depending upon the thickness of double layer, the friction of the membrane layer of a particle can either retard or accelerate its movement, an interesting result which has not been reported previously. This work is the first attempt to show solid evidence for the influence of a boundary on the effect of DLP and the electrophoretic behavior of soft particles. The model proposed is verified by the experimental data in the literature. The results of numerical simulation provide valuable information for the design of bio-analytical apparatus such as nanopore-based sensing applications and for the interpretation of relevant experimental data. Copyright © 2011 Elsevier B.V. All rights reserved.

Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

NASA Astrophysics Data System (ADS)

Barahuie, Farahnaz; Hussein, Mohd Zobir; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

2014-09-01

A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro.

Use of UO 2 films for electrochemical studies

NASA Astrophysics Data System (ADS)

Miserque, F.; Gouder, T.; Wegen, D. H.; Bottomley, P. D. W.

2001-10-01

UO 2 films have been prepared by dc reactive sputtering of a uranium metal target in an Ar/O 2 atmosphere. We have used the films deposited on gold substrates as working electrodes for electrochemical investigations as simulating the surfaces of fuel pellets. Film composition was determined by photoelectron spectroscopy (XPS and UPS) and X-ray diffraction (XRD). The oxide stoichiometry as a function of deposition conditions was determined and the appropriate conditions for UO 2.0 formation established. AC impedance and cyclic voltammetry measurements were performed. A double RC electrical equivalent circuit was used to fit the data from impedance measurements, similar to those used in unirradiated UO 2 or spent fuel pellets. However due to the porosity or adhesion defects on the thin films that permitted a direct contact between the solution and the gold substrate, we were obliged to add a contribution simulating the water-gold system. Cyclic voltammetry measurements show the influence of pH on the dissolution mechanism. Alkaline solutions permit the formation of an oxidised layer (UO 2.33) which is not present in the acidic solutions. In both pH=2 and pH=6 solutions, a U VI species layer is formed.

Specific DNA duplex formation at an artificial lipid bilayer: towards a new DNA biosensor technology.

PubMed

Werz, Emma; Korneev, Sergei; Montilla-Martinez, Malayko; Wagner, Richard; Hemmler, Roland; Walter, Claudius; Eisfeld, Jörg; Gall, Karsten; Rosemeyer, Helmut

2012-02-01

A novel technique is described which comprises a base-specific DNA duplex formation at a lipid bilayer-H(2) O-phase boundary layer. Two different probes of oligonucleotides both carrying a double-tailed lipid at the 5'-terminus were incorporated into stable artificial lipid bilayers separating two compartments (cis/trans-channel) of an optically transparent microfluidic sample carrier with perfusion capabilities. Both the cis- and trans-channels are filled with saline buffer. Injection of a cyanine-5-labeled target DNA sequence, which is complementary to only one of the oligonucleotide probes, into the cis-channel, followed by a thorough perfusion, leads to an immobilization of the labeled complementary oligonucleotide on the membrane as detected by single-molecule fluorescence spectroscopy and microscopy. In the case of fluorescent but non-complementary DNA sequences, no immobilized fluorescent oligonucleotide duplex could be detected on the membrane. This clearly verifies a specific duplex formation at the membrane interface. Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.

ELECTRON MICROSCOPE AND X-RAY DIFFRACTION STUDIES ON A HOMOLOGOUS SERIES OF SATURATED PHOSPHATIDYLCHOLINES.

PubMed

ELBERS, P F; VERVERGAERT, P H

1965-05-01

Three homologous saturated phosphatidylcholines were studied by electron microscopy after tricomplex fixation. The results are compared with those obtained by x-ray diffraction analysis of the same and some other homologous compounds, in the dry crystalline state and after tricomplex fixation. By electron microscopy alternating dark and light bands are observed which are likely to correspond to phosphatide double layers. X-Ray diffraction reveals the presence of lamellar structures of regular spacing. The layer spacings obtained by both methods are in good agreement. From the electron micrographs the width of the polar parts of the double layers can be derived directly. The width of the carboxylglycerylphosphorylcholine moiety of the layers is found by extrapolating the x-ray diffraction data to zero chain length of the fatty acids. When from this width the contribution of the carboxylglyceryl part of the molecules is subtracted, again we find good agreement with the electron microscope measurements. An attempt has been made to account for the different layer spacings measured in terms of orientation of the molecules within the double layers.

Slow electron acoustic double layer (SEADL) structures in bi-ion plasma with trapped electrons

NASA Astrophysics Data System (ADS)

Shan, Shaukat Ali; Imtiaz, Nadia

2018-05-01

The properties of ion acoustic double layer (IADL) structures in bi-ion plasma with electron trapping are investigated by using the quasi-potential analysis. The κ-distributed trapped electrons number density expression is truncated to some finite order of the electrostatic potential. By utilizing the reductive perturbation method, a modified Schamel equation which describes the evolution of the slow electron acoustic double layer (SEADL) with the modified speed due to the presence of bi-ion species is investigated. The Sagdeev-like potential has been derived which accounts for the effect of the electron trapping and superthermality in a bi-ion plasma. It is found that the superthermality index, the trapping efficiency of electrons, and ion to electron temperature ratio are the inhibiting parameters for the amplitude of the slow electron acoustic double layers (SEADLs). However, the enhanced population of the cold ions is found to play a supportive role for the low frequency DLs in bi-ion plasmas. The illustrations have been presented with the help of the bi-ion plasma parameters in the Earth's ionosphere F-region.

The role of double TiO 2 layers at the interface of FeSe/SrTiO 3 superconductors

DOE PAGES

Zou, Ke; Bozovic, Ian; Mandal, Subhasish; ...

2016-05-16

We determine the surface reconstruction of SrTiO 3 used to achieve superconducting FeSe films in experiments, which is different from the 1×1 TiO 2-terminated SrTiO 3 assumed by most previous theoretical studies. In particular, we identify the existence of a double TiO 2 layer at the FeSe/SrTiO 3 interface that plays two important roles. First, it facilitates the epitaxial growth of FeSe. Second, ab initio calculations reveal a strong tendency for electrons to transfer from an oxygen deficient SrTiO 3 surface to FeSe when the double TiO 2 layer is present. The double layer helps to remove the hole pocketmore » in the FeSe at the Γ point of the Brillouin zone and leads to a band structure characteristic of superconducting samples. The characterization of the interface structure presented here is a key step towards the resolution of many open questions about this superconductor.« less

Superplastic Forming/Diffusion Bonding Without Interlayer of 5A90 Al-Li Alloy Hollow Double-Layer Structure

NASA Astrophysics Data System (ADS)

Jiang, Shaosong; Jia, Yong; Lu, Zhen; Shi, Chengcheng; Zhang, Kaifeng

2017-09-01

The hollow double-layer structure of 5A90 Al-Li alloy was fabricated by SPF/DB process in this study. The characteristics and mechanism of 5A90 Al-Li alloy with respect to superplasticity and diffusion bonding were investigated. Tensile tests showed that the optimal elongation of tensile specimens was 243.97% at the temperature of 400 °C and the strain rate of 0.001 s-1. Effect of the surface roughness, bonding temperature and bonding time to determine the microstructure and mechanical properties of diffusion bonding joints was investigated, and the optimum bonding parameters were 540 °C/2.5 h/Ra18. Through the finite element simulation, it could be found that the SPF/DB process of hollow double-layer structure was feasible. The hollow double-layer structure of 5A90 Al-Li alloy was manufactured, showing that the thickness distribution of the bonding area was uniform and the thinnest part was the round corner. The SEM images of diffusion bonding joints showed that sound bonding interfaces were obtained in which no discontinuity existed.

Structure of water clusters on graphene: A classical molecular dynamics approach

NASA Astrophysics Data System (ADS)

Maekawa, Yuki; Sasaoka, Kenji; Yamamoto, Takahiro

2018-03-01

The microscopic structure of surface water adsorbed on graphene is elucidated theoretically by classical molecular dynamics simulation. At a low temperature (100 K), the main polygon consisting of hydrogen bonds in single-layered water on graphene is tetragonal, whereas the dominant polygons in double-layered water are tetragonal, pentagonal, and hexagonal. On the other hand, at room temperature, the tetragonal, pentagonal, and hexagonal water clusters are the main structures in both single- and double-layered water.

Application of amorphous carbon based materials as antireflective coatings on crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

da Silva, D. S.; Côrtes, A. D. S.; Oliveira, M. H.; Motta, E. F.; Viana, G. A.; Mei, P. R.; Marques, F. C.

2011-08-01

We report on the investigation of the potential application of different forms of amorphous carbon (a-C and a-C:H) as an antireflective coating for crystalline silicon solar cells. Polymeric-like carbon (PLC) and hydrogenated diamond-like carbon films were deposited by plasma enhanced chemical vapor deposition. Tetrahedral amorphous carbon (ta-C) was deposited by the filtered cathodic vacuum arc technique. Those three different amorphous carbon structures were individually applied as single antireflective coatings on conventional (polished and texturized) p-n junction crystalline silicon solar cells. Due to their optical properties, good results were also obtained for double-layer antireflective coatings based on PLC or ta-C films combined with different materials. The results are compared with a conventional tin dioxide (SnO2) single-layer antireflective coating and zinc sulfide/magnesium fluoride (ZnS/MgF2) double-layer antireflective coatings. An increase of 23.7% in the short-circuit current density, Jsc, was obtained using PLC as an antireflective coating and 31.7% was achieved using a double-layer of PLC with a layer of magnesium fluoride (MgF2). An additional increase of 10.8% was obtained in texturized silicon, representing a total increase (texturization + double-layer) of about 40% in the short-circuit current density. The potential use of these materials are critically addressed considering their refractive index, optical bandgap, absorption coefficient, hardness, chemical inertness, and mechanical stability.

Double-walled structure of anodic TiO2 nanotubes in H3PO4/NH4F mixed electrolyte

NASA Astrophysics Data System (ADS)

Chen, Siyu; Chen, Ying; Li, Chengyuan; Ouyang, Huijun; Qin, Shuai; Song, Ye

2018-04-01

Normally, the well-ordered anodic TiO2 nanotubes (ATNTs) are obtained in NH4F electrolyte, after annealing, the double-walled structure of nanotubes will appear. Here, after adding H3PO4 into NHF4 electrolyte, we got the double-walled structure of nanotubes by anodizing without annealing, which means the direct existence of anion-contaminated layer in ATNTs. Influence of H3PO4 content on anodizing voltage and morphology of ATNTs were compared in detail. The XRD pattern illustrated that the crystallinity decreases with increasing H3PO4 concentration, and the anion-contaminated layer thickens with the increase of H3PO4 concentration. Meanwhile, the existence of the anion-contaminated layer also proved the limitations of the filed-assisted dissolution theory, while the double-walled structure can be explained by oxygen bubble model and plastic flow model.

Horseradish peroxidase-nanoclay hybrid particles of high functional and colloidal stability.

PubMed

Pavlovic, Marko; Rouster, Paul; Somosi, Zoltan; Szilagyi, Istvan

2018-08-15

Highly stable dispersions of enzyme-clay nanohybrids of excellent horseradish peroxidase activity were developed. Layered double hydroxide nanoclay was synthesized and functionalized with heparin polyelectrolyte to immobilize the horseradish peroxidase enzyme. The formation of a saturated heparin layer on the platelets led to charge inversion of the positively charged bare nanoclay and to highly stable aqueous dispersions. Great affinity of the enzyme to the surface modified platelets resulted in strong horseradish peroxidase adsorption through electrostatic and hydrophobic interactions as well as hydrogen bonding network and prevented enzyme leakage from the obtained material. The enzyme kept its functional integrity upon immobilization and showed excellent activity in decomposition of hydrogen peroxide and oxidation of an aromatic compound in the test reactions. In addition, remarkable long term functional stability of the enzyme-nanoclay hybrid was observed making the developed colloidal system a promising antioxidant candidate in biomedical treatments and industrial processes. Copyright © 2018 Elsevier Inc. All rights reserved.

Fabrication and properties of gallium phosphide variable colour displays

NASA Technical Reports Server (NTRS)

Effer, D.; Macdonald, R. A.; Macgregor, G. M.; Webb, W. A.; Kennedy, D. I.

1973-01-01

The unique properties of single-junction gallium phosphide devices incorporating both red and green radiative recombination centers were investigated in application to the fabrication of monolithic 5 x 7 displays capable of displaying symbolic and alphanumeric information in a multicolor format. A number of potentially suitable material preparation techniques were evaluated in terms of both material properties and device performance. Optimum results were obtained for double liquid-phase-epitaxial process in which an open-tube dipping technique was used for n-layer growth and a sealed tipping procedure for subsequent p-layer growth. It was demonstrated that to prepare devices exhibiting a satisfactory range of dominant wavelengths which can be perceived as distinct emission colors extending from the red through green region of the visible spectrum involves a compromise between the material properties necessary for efficient red emission and those considered optimum for efficient green emission.

Comprehensive Insights into the Reactivity of Electrolytes Based on Sodium Ions.

PubMed

Eshetu, Gebrekidan Gebresilassie; Grugeon, Sylvie; Kim, Huikyong; Jeong, Sangsik; Wu, Liming; Gachot, Gregory; Laruelle, Stephane; Armand, Michel; Passerini, Stefano

2016-03-08

We report a systematic investigation of Na-based electrolytes that comprise various NaX [X=hexafluorophosphate (PF6 ), perchlorate (ClO4 ), bis(trifluoromethanesulfonyl)imide (TFSI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI), and bis(fluorosulfonyl)imide (FSI)] salts and solvent mixtures [ethylene carbonate (EC)/dimethyl carbonate (DMC), EC/diethyl carbonate (DEC), and EC/propylene carbonate (PC)] with respect to the Al current collector stability, formation of soluble degradation compounds, reactivity towards sodiated hard carbon (Nax -HC), and solid-electrolyte interphase (SEI) layer formation. Cyclic voltammetry demonstrates that the stability of Al is highly influenced by the nature of the anions, solvents, and additives. GC-MS analysis reveals that the formation of SEI telltales depends on the nature of the linear alkyl carbonates and the battery chemistry (Li(+) vs. Na(+) ). FTIR spectroscopy shows that double alkyl carbonates are the main components of the SEI layer on Nax -HC. In the presence of Na salts, EC/DMC and EC/DEC presented a higher reactivity towards Nax -HC than EC/PC. For a fixed solvent mixture, the onset temperature follows the sequence NaClO4

Mechanically delaminated few layered MoS2 nanosheets based high performance wire type solid-state symmetric supercapacitors

NASA Astrophysics Data System (ADS)

Krishnamoorthy, Karthikeyan; Pazhamalai, Parthiban; Veerasubramani, Ganesh Kumar; Kim, Sang Jae

2016-07-01

Two dimensional nanostructures are increasingly used as electrode materials in flexible supercapacitors for portable electronic applications. Herein, we demonstrated a ball milling approach for achieving few layered molybdenum disulfide (MoS2) via exfoliation from their bulk. Physico-chemical characterizations such as X-ray diffraction, field emission scanning electron microscope, and laser Raman analyses confirmed the occurrence of exfoliated MoS2 sheets with few layers from their bulk via ball milling process. MoS2 based wire type solid state supercapacitors (WSCs) are fabricated and examined using cyclic voltammetry (CV), electrochemical impedance spectroscopy, and galvanostatic charge discharge (CD) measurements. The presence of rectangular shaped CV curves and symmetric triangular shaped CD profiles suggested the mechanism of charge storage in MoS2 WSC is due to the formation of electrochemical double layer capacitance. The MoS2 WSC device delivered a specific capacitance of 119 μF cm-1, and energy density of 8.1 nW h cm-1 with better capacitance retention of about 89.36% over 2500 cycles, which ensures the use of the ball milled MoS2 for electrochemical energy storage devices.

Cryogenic THD and DT layer implosions with high density carbon ablators in near-vacuum hohlraums

DOE PAGES

Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; ...

2015-06-02

High Density Carbon (HDC or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a DT layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a THD layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightlymore » oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 x 10¹⁵ neutrons, 40% of the 1D simulated yield.« less

Design and evaluation of bilayered buccal film preparations for local administration of lidocaine hydrochloride.

PubMed

Preis, Maren; Woertz, Christina; Schneider, Katharina; Kukawka, Jennifer; Broscheit, Jens; Roewer, Norbert; Breitkreutz, Jörg

2014-04-01

Bilayered oromucosal film preparations (buccal films) offer a promising way to enable drug administration via the oral cavity. Adding a non-soluble or slowly eroding/dissolving backing layer to a mucoadhesive drug-loaded layer enables unidirectional drug delivery. The aim of this study was to investigate different approaches to the manufacture of bilayered films and to examine their properties by applying different characterization methods including an optimized experimental setup for the study of drug release from bilayered films. A solvent suitability study was performed screening over 15 polymers with respect to their feasibility for viscous film formation for film preparation by solvent casting method. Two methods (double-casting and pasting) were found as suitable methods for bilayered film manufacturing. Results from drug release experiments indicated that slowly eroding hypromellose backing layer films revealed the best shielding of the drug-loaded layer to enable unidirectional drug release. In summary, manufacturing of bilayered films using the described methods was feasible. Furthermore, the use of an optimized experimental setup for drug dissolution studies enabled monitoring of drug release without delays in sampling. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation and characterization of mono- and multilayer films of polymerizable 1,2-polybutadiene using the Langmuir-Blodgett technique.

PubMed

Hitrik, Maria; Gutkin, Vitaly; Lev, Ovadia; Mandler, Daniel

2011-10-04

The essence of this study is to apply the Langmuir-Blodgett (LB) technique for assembling asymmetric membranes. Accordingly, Langmuir films of a (further) polymerizable polymer, 1,2-polybutadiene (1,2-pbd), were studied and transferred onto different solid supports, such as gold, indium tin oxide (ITO), and silicon. The layers were characterized both at the air/water interface as well as on different substrates using numerous methods including cyclic voltammetry, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, X-ray photoelectron spectroscopy, and reflection-absorption Fourier transform infrared spectroscopy. The Langmuir films were stable at the air-water interface as long as they were not exposed to UV irradiation. The LB films formed disorganized layers, which gradually blocked the permeation of different species with increasing the number of deposited layers. The thickness was ca. 4-7 Å per layer. Irradiating the Langmuir films caused their cross-linking at the air-water interface. Furthermore, we took advantage of the reactivity of the double bond of the LB films on the solid supports and graft polymerized acrylic acid on top of the 1,2-pbd layers. This approach is the basis of the formation of an asymmetric membrane that requires different porosity on both of its sides. © 2011 American Chemical Society

Frictional Magneto-Coulomb Drag in Graphene Double-Layer Heterostructures.

PubMed

Liu, Xiaomeng; Wang, Lei; Fong, Kin Chung; Gao, Yuanda; Maher, Patrick; Watanabe, Kenji; Taniguchi, Takashi; Hone, James; Dean, Cory; Kim, Philip

2017-08-04

Coulomb interaction between two closely spaced parallel layers of conductors can generate the frictional drag effect by interlayer Coulomb scattering. Employing graphene double layers separated by few-layer hexagonal boron nitride, we investigate density tunable magneto- and Hall drag under strong magnetic fields. The observed large magnetodrag and Hall-drag signals can be related with Laudau level filling status of the drive and drag layers. We find that the sign and magnitude of the drag resistivity tensor can be quantitatively correlated to the variation of magnetoresistivity tensors in the drive and drag layers, confirming a theoretical formula for magnetodrag in the quantum Hall regime. The observed weak temperature dependence and ∼B^{2} dependence of the magnetodrag are qualitatively explained by Coulomb scattering phase-space argument.

Accelerated cell-sheet recovery from a surface successively grafted with polyacrylamide and poly(N-isopropylacrylamide).

PubMed

Akiyama, Yoshikatsu; Kikuchi, Akihiko; Yamato, Masayuki; Okano, Teruo

2014-08-01

A double polymeric nanolayer consisting of poly(N-isopropylacrylamide) (PIPAAm) and hydrophilic polyacrylamide (PAAm) was deposited on tissue culture polystyrene (TCPS) surfaces using electron beam irradiation to form a new temperature-responsive cell culture surface in which the basal hydrophilic PAAm component in the double polymeric layer promotes the hydration of the upper PIPAAm layer and induces rapid cell detachment compared to a conventional temperature-responsive cell culture surface, PIPAAm-grafted TCPS (PIPAAm-TCPS). Take-off angle-dependent X-ray photoelectron spectroscopy spectral analysis demonstrated that the grafted PIPAAm and PAAm components were located in the upper and basal regions of the double polymeric layer, respectively, suggesting that the double polymeric layer forms an inter-penetrating-network-like structure with PAAm at the basal portion of the PIPAAm grafted chains. The wettability of the temperature-responsive cell culture surfaces with the double polymeric layer tended to be more hydrophilic, with an increase in the basal PAAm graft density at a constant PIPAAm graft density. However, when the graft densities of the upper PIPAAm and basal PAAm were optimized, the resulting temperature-responsive cell culture surface with the double polymeric layer exhibited rapid cell detachment while maintaining cell adhesive character comparable to that of PIPAAm-TCPS. The cell adhesive character was altered from cell-adhesive to cell-repellent with increasing PAAm or PIPAAm graft density. The cell adhesive character of the temperature-responsive cell culture surfaces was relatively consistent with their contact angles. These results strongly suggest that the basal PAAm surface properties affect the degree of hydration and dehydration of the subsequently grafted PIPAAm. In addition, the roles of the hydrophilic component in accelerating cell detachment are further discussed in terms of the mobility of the grafted PIPAAm chains. Applications of this insight might be useful for designing temperature-responsive cell culture surfaces for achieving efficient cell culture and quick target cell detachment. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Tribological Behavior of Al-Cr Coating Obtained by Dgpsm and IIP Composite Technology

NASA Astrophysics Data System (ADS)

Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Chen, Yu; Tao, Xuewei

An Al-Cr composite alloyed layer composed of an Al enriched layer, a Cr enriched layer and a transition layer from the surface to the bulk along the cross-section was deposited on a 45# steel substrate by composite technology, where Cr was deposited using double glow plasma surface metallurgy (DGPSM), and Al was then implanted by ion implantation (IIP) to achieve higher micro-hardness and excellent abrasive resistance. The composite alloyed layer is approximately 5μm, and as metallurgical adherence to the substrate. The phases are Al8Cr5, Fe2AlCr, Cr23C6, Cr (Al) and Fe (Cr, Al) solid solution. The wear resistance tests were performed under various rotational speed (i.e. 280, 560 and 840r/min) with silicon nitride balls as the counterface material at ambient temperature. The Al-Cr composite alloyed layer exhibits excellent wear resistance when the speed is 280r/min with a friction coefficient as low as 0.3, which is attributed to Al8Cr5 in the Al implanted layer that withstands abrasive wear. Better wear resistance (friction coefficient: 0.254) at 560r/min is resulted from the formation of a high micro-hardness zone, and an oxidation layer with lubrication capacity. In addition, the composite alloyed layer suffers severe oxidative wear and adhesive wear at 840r/min due to the increment of the frictional heating. When compared to the 45# steel substrate, the enhanced wear resistance of the Al-Cr composite alloyed layer demonstrates the viable method developed in this work.

Ferroelectric polarization induces electric double layer bistability in electrolyte-gated field-effect transistors.

PubMed

Fabiano, Simone; Crispin, Xavier; Berggren, Magnus

2014-01-08

The dense surface charges expressed by a ferroelectric polymeric thin film induce ion displacement within a polyelectrolyte layer and vice versa. This is because the density of dipoles along the surface of the ferroelectric thin film and its polarization switching time matches that of the (Helmholtz) electric double layers formed at the ferroelectric/polyelectrolyte and polyelectrolyte/semiconductor interfaces. This combination of materials allows for introducing hysteresis effects in the capacitance of an electric double layer capacitor. The latter is advantageously used to control the charge accumulation in the semiconductor channel of an organic field-effect transistor. The resulting memory transistors can be written at a gate voltage of around 7 V and read out at a drain voltage as low as 50 mV. The technological implication of this large difference between write and read-out voltages lies in the non-destructive reading of this ferroelectric memory.

Local Deplanation Of Double Reinforced Beam Cross Section Under Bending

NASA Astrophysics Data System (ADS)

Baltov, Anguel; Yanakieva, Ana

2015-12-01

Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

Si/Ge double-layered nanotube array as a lithium ion battery anode.

PubMed

Song, Taeseup; Cheng, Huanyu; Choi, Heechae; Lee, Jin-Hyon; Han, Hyungkyu; Lee, Dong Hyun; Yoo, Dong Su; Kwon, Moon-Seok; Choi, Jae-Man; Doo, Seok Gwang; Chang, Hyuk; Xiao, Jianliang; Huang, Yonggang; Park, Won Il; Chung, Yong-Chae; Kim, Hansu; Rogers, John A; Paik, Ungyu

2012-01-24

Problems related to tremendous volume changes associated with cycling and the low electron conductivity and ion diffusivity of Si represent major obstacles to its use in high-capacity anodes for lithium ion batteries. We have developed a group IVA based nanotube heterostructure array, consisting of a high-capacity Si inner layer and a highly conductive Ge outer layer, to yield both favorable mechanics and kinetics in battery applications. This type of Si/Ge double-layered nanotube array electrode exhibits improved electrochemical performances over the analogous homogeneous Si system, including stable capacity retention (85% after 50 cycles) and doubled capacity at a 3C rate. These results stem from reduced maximum hoop strain in the nanotubes, supported by theoretical mechanics modeling, and lowered activation energy barrier for Li diffusion. This electrode technology creates opportunities in the development of group IVA nanotube heterostructures for next generation lithium ion batteries. © 2011 American Chemical Society

Incorporation of rare-earth ions in Mg-Al layered double hydroxides: intercalation with an [Eu(EDTA)] - chelate

NASA Astrophysics Data System (ADS)

Li, Cang; Wang, Ge; Evans, David G.; Duan, Xue

2004-12-01

Reaction of an aqueous slurry of an Mg 2Al-NO 3 layered double hydroxide with a four-fold excess of Na[Eu(EDTA)] gives a material which analyses for Mg 0.68Al 0.32(OH) 2[Eu(EDTA)] 0.10(CO 3) 0.11·0.66H 2O. The interlayer spacing of the material is 13.8 Å, corresponding to a gallery height of 9.0 Å, which accords with the maximal dimensions (9-10 Å) of the anion in metal-EDTA complex salts as determined by single crystal X-ray diffraction. Geometrical considerations show that the charge density on the layered double hydroxide layers is too high to be balanced by intercalation of [Eu(EDTA)] - alone, necessitating the co-intercalation of carbonate ions which have a much higher charge density.

Influence of nonelectrostatic ion-ion interactions on double-layer capacitance

NASA Astrophysics Data System (ADS)

Zhao, Hui

2012-11-01

Recently a Poisson-Helmholtz-Boltzmann (PHB) model [Bohinc , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.031130 85, 031130 (2012)] was developed by accounting for solvent-mediated nonelectrostatic ion-ion interactions. Nonelectrostatic interactions are described by a Yukawa-like pair potential. In the present work, we modify the PHB model by adding steric effects (finite ion size) into the free energy to derive governing equations. The modified PHB model is capable of capturing both ion specificity and ion crowding. This modified model is then employed to study the capacitance of the double layer. More specifically, we focus on the influence of nonelectrostatic ion-ion interactions on charging a double layer near a flat surface in the presence of steric effects. We numerically compute the differential capacitance as a function of the voltage under various conditions. At small voltages and low salt concentrations (dilute solution), we find out that the predictions from the modified PHB model are the same as those from the classical Poisson-Boltzmann theory, indicating that nonelectrostatic ion-ion interactions and steric effects are negligible. At moderate voltages, nonelectrostatic ion-ion interactions play an important role in determining the differential capacitance. Generally speaking, nonelectrostatic interactions decrease the capacitance because of additional nonelectrostatic repulsion among excess counterions inside the double layer. However, increasing the voltage gradually favors steric effects, which induce a condensed layer with crowding of counterions near the electrode. Accordingly, the predictions from the modified PHB model collapse onto those computed by the modified Poisson-Boltzmann theory considering steric effects alone. Finally, theoretical predictions are compared and favorably agree with experimental data, in particular, in concentrated solutions, leading one to conclude that the modified PHB model adequately predicts the diffuse-charge dynamics of the double layer with ion specificity and steric effects.

AFRRI (Armed Forces Radiobiology Research Institute) Reports, July, August and September 1987.

DTIC Science & Technology

1987-11-01

mononuclear cell layer obtained after Percol isolation contained approximately 90% mono- cytes as assessed by esterase staining. In most experiments...forming cell) were assayed using the double layer agar technique basically as described by Hagan et al. (22). The culture medium was double strength CMRL...trypticase soy broth, 20 g/ml L-asparagine. and penicillin-streptomycin. In the bottom layer of 35 mm plastic Petri dishes was 1 ml of a 1:1 mixture of culture

Double layered tailorable advanced blanket insulation

NASA Technical Reports Server (NTRS)

Falstrup, D.

1983-01-01

An advanced flexible reusable surface insulation material for future space shuttle flights was investigated. A conventional fly shuttle loom with special modifications to weave an integral double layer triangular core fabric from quartz yarn was used. Two types of insulating material were inserted into the cells of the fabric, and a procedure to accomplish this was developed. The program is follow up of a program in which single layer rectangular cell core fabrics are woven and a single type of insulating material was inserted into the cells.

Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

NASA Astrophysics Data System (ADS)

Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

2005-08-01

Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

Photocatalytic organic transformation by layered double hydroxides: highly efficient and selective oxidation of primary aromatic amines to their imines under ambient aerobic conditions.

PubMed

Yang, Xiu-Jie; Chen, Bin; Li, Xu-Bing; Zheng, Li-Qiang; Wu, Li-Zhu; Tung, Chen-Ho

2014-06-25

We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation.

In situ heat treatment from multiple layers of a tar sands formation

DOEpatents

Vinegar, Harold J.

2010-11-30

A method for treating a tar sands formation is disclosed. The method includes providing a drive fluid to a first hydrocarbon containing layer of the formation to mobilize at least some hydrocarbons in the first layer. At least some of the mobilized hydrocarbons are allowed to flow into a second hydrocarbon containing layer of the formation. Heat is provided to the second layer from one or more heaters located in the second layer. At least some hydrocarbons are produced from the second layer of the formation.

Effects of dust polarity and nonextensive electrons on the dust-ion acoustic solitons and double layers in earth atmosphere

NASA Astrophysics Data System (ADS)

Ghobakhloo, Marzieh; Zomorrodian, Mohammad Ebrahim; Javidan, Kurosh

2018-05-01

Propagation of dustion acoustic solitary waves (DIASWs) and double layers is discussed in earth atmosphere, using the Sagdeev potential method. The best model for distribution function of electrons in earth atmosphere is found by fitting available data on different distribution functions. The nonextensive function with parameter q = 0.58 provides the best fit on observations. Thus we analyze the propagation of localized waves in an unmagnetized plasma containing nonextensive electrons, inertial ions, and negatively/positively charged stationary dust. It is found that both compressive and rarefactive solitons as well as double layers exist depending on the sign (and the value) of dust polarity. Characters of propagated waves are described using the presented model.

Fabricating solid carbon porous electrodes from powders

DOEpatents

Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

1997-01-01

Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

Fabricating solid carbon porous electrodes from powders

DOEpatents

Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

1997-06-10

Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon composites with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to high surface area carbons, fuel cell electrodes can be produced. 1 fig.

Strategy for improved frequency response of electric double-layer capacitors

NASA Astrophysics Data System (ADS)

Wada, Yoshifumi; Pu, Jiang; Takenobu, Taishi

2015-10-01

We propose a strategy for improving the response speed of electric double-layer capacitors (EDLCs) and electric double-layer transistors (EDLTs), based on an asymmetric structure with differently sized active materials and gate electrodes. We validate the strategy analytically by a classical calculation and experimentally by fabricating EDLCs with asymmetric Au electrodes (1:50 area ratio and 7.5 μm gap distance). The performance of the EDLCs is compared with that of conventional symmetric EDLCs. Our strategy dramatically improved the cut-off frequency from 14 to 93 kHz and this improvement is explained by fast charging of smaller electrodes. Therefore, this approach is particularly suitable to EDLTs, potentially expanding the applicability to medium speed (kHz-MHz) devices.

The role of upstream distal electrodes in mitigating electrochemical degradation of ionic liquid ion sources

NASA Astrophysics Data System (ADS)

Brikner, Natalya; Lozano, Paulo C.

2012-11-01

Ionic liquid ion sources produce molecular ions from micro-tip emitters wetted with room-temperature molten salts. When a single ion polarity is extracted, counterions accumulate and generate electrochemical reactions that limit the source lifetime. The dynamics of double layer formation are reviewed and distal electrode contacts are introduced to resolve detrimental electrochemical decomposition effects at the micro-tip apex. By having the emitter follow the ionic liquid potential, operation can be achieved for an extended period of time with no apparent degradation of the material, indicating that electrochemistry can be curtailed and isolated to the upstream distal electrode.

Magnetocapacitance effect in core/shell NiO nanoparticles

NASA Astrophysics Data System (ADS)

Roy, Subir; Kambhala, Nagaiah; Angappane, S.

2018-04-01

The exchange bias and magnetocapacitance properties of nickel oxide nanoparticles of average particle size 50 nm have been studied. NiO nanoparticles of uniform size distribution were synthesized by a sol-gel method using nickel acetate and polyvinyl acetate. The magnetic measurements show the ferromagnetic like behavior exhibiting exchange bias effect indicative of the formation of core/shell structure of NiO with a antiferromagnetic core and ferromagnetic shell. An electrical double layer capacitance behavior was observed for NiO nanoparticles in the cyclic voltammetry measurement, and it was found that the value of capacitance decreased by about 26 % under the application of magnetic field of 0.1 T.

Double emulsion formation through hierarchical flow-focusing microchannel

NASA Astrophysics Data System (ADS)

Azarmanesh, Milad; Farhadi, Mousa; Azizian, Pooya

2016-03-01

A microfluidic device is presented for creating double emulsions, controlling their sizes and also manipulating encapsulation processes. As a result of three immiscible liquids' interaction using dripping instability, double emulsions can be produced elegantly. Effects of dimensionless numbers are investigated which are Weber number of the inner phase (Wein), Capillary number of the inner droplet (Cain), and Capillary number of the outer droplet (Caout). They affect the formation process, inner and outer droplet size, and separation frequency. Direct numerical simulation of governing equations was done using volume of fluid method and adaptive mesh refinement technique. Two kinds of double emulsion formation, the two-step and the one-step, were simulated in which the thickness of the sheath of double emulsions can be adjusted. Altering each dimensionless number will change detachment location, outer droplet size and droplet formation period. Moreover, the decussate regime of the double-emulsion/empty-droplet is observed in low Wein. This phenomenon can be obtained by adjusting the Wein in which the maximum size of the sheath is discovered. Also, the results show that Cain has significant influence on the outer droplet size in the two-step process, while Caout affects the sheath in the one-step formation considerably.

Investigation of Corrosion Behavior of Ti/TiN Multilayers on Al7075 Deposited by High-Vacuum Magnetron Sputtering in 3.5% NaCl Solution

NASA Astrophysics Data System (ADS)

Molavi, Esfandiar; Shanaghi, Ali; Chu, Paul K.

2018-05-01

Although Al 7075 has many favorable mechanical properties such as the large strength-to-weight ratio, the relatively poor corrosion resistance has restricted industrial applications. In this work, Ti/TiN as hard multilayered and nanostructured coatings are deposited on the relatively soft Al 7075 structure by high-vacuum radio-frequency magnetron sputtering and the phase, structure, and morphology are investigated in details. The corrosion behavior is evaluated by electrochemical impedance spectroscopy in 3.5% NaCl at a pH of 7.5 for 1, 6, 12, 24, 36, 48, 60, and 72 h. At time points of 1, 6, 12, and 24 h, primary oxide layers and double layers are formed, but the corrosive medium penetrates the primary titanium nitride columnar structure. At longer time points of 24, 36, 48, 60, and 72 h, formation of stronger oxide and double layers leads to better corrosion resistance which is 14.8 times better than that observed from the uncoated substrate after immersion for 36 h. According to R ct, the corrosion resistances of the short and long immersion groups are 808.5-1984 and 808.5-1248 kΩ cm2, respectively, thereby confirming the effectiveness of the Ti/TiN coating against corrosion in comparison with the corrosion resistance of 84.3 kΩ cm2 observed from the uncoated Al 7075. The smallest corrosion resistance of 808.5 kΩ cm2 observed at the time point of 24 h is 9.6 times that of the uncoated substrate.

Detection of Osteopontin in the pericyst of human hepatic Echinococcus granulosus.

PubMed

Peng, Xinyu; Li, Jianhui; Wu, Xiangwei; Zhang, Shijie; Niu, Jianhua; Chen, Xiaoping; Yao, Jin; Sun, Hong

2006-12-01

It aims at investigating the expression and distribution of the Osteopontin (OPN) in the pericyst of human hepatic Echinococcus granulosus and their related significances. Sixty pericysts excised by "sub-adventitial cystectomy" were studied. OPN was detected in 80% (48/60) of cysts by Western blotting and distributed in the side of "exocyst" layer directing to the parasite, also macrophages were identified in the vicinity of OPN by immunohistochemistry staining. The coexpression of OPN and CD68 was observed by immunofluorescence double labeling and analyzed by Image-Pro Plus 5.1; with special stain techniques, variable degrees of calcium deposits were observed in 80% (48/60) cysts, and the calcium deposits concurrencely found with the OPN expression. The selective distribution of OPN, calcium in the "exocyst" provides a new pathological evidence for the "sub-adventitial cystectomy" we developed. The pericyst of hepatic E. granulosus consists of two detachable layers with different formative mechanisms: the "exocyst" layer directing towards the cyst of parasite was the result of granulomatous reaction; also the results suggest OPN is one regulator in the granulomatous reaction and calcification of "exocyst".

Formation of blade and slot die coated small molecule multilayers for OLED applications studied theoretically and by XPS depth profiling

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

Peters, Katharina; Raupp, Sebastian, E-mail: sebastian.raupp@kit.edu; Scharfer, Philip

2016-06-15

Slot die coaters especially designed for low material consumption and doctor blades were used to process small molecule solutions for organic light-emitting diodes (OLEDs). Optimum process parameters were developed for the large-scale coating techniques to generate stable single and multiple layers only a few nanometers thick. Achieving a multilayer architecture for solution-processed OLEDs is the most challenging step. X-ray photoelectron spectroscopy sputter depth profiling was performed to determine defined interfaces between coated organic layers. Commercially available small molecules NPB (N,N’-Di(1-naphthyl)-N,N’-diphenyl-(1,1’-biphenyl)-4,4’-diamine) and BAlq (Bis(8-hdroxy-2methylquinoline)-(4-phenylphenoxy)aluminum), originally developed for vacuum deposition, were used as hole, respectively electron transport material. Defined double-layers were processedmore » with both scalable coating methods using the orthogonal solvent approach. The use of non-orthogonal solvents resulted in complete intermixing of the material. The results are explained by calculations of solubilities and simulating drying and diffusion kinetics of the small molecule solutions.« less

Epitaxial growth of (001)-oriented Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films on a-plane sapphire with an MgO/ZnO bridge layer

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

Xiao Bo; Liu Hongrui; Avrutin, Vitaliy

2009-11-23

High quality (001)-oriented Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) thin films have been grown on a-plane sapphire (1120) by rf magnetron sputtering using a double bridge layer consisting of (0001)-oriented ZnO (50 nm) and (001)-oriented MgO (10 nm) prepared by plasma-assisted molecular beam epitaxy. X-ray diffraction revealed the formation of three sets of in-plane BST domains, offset from one another by 30 deg., which is consistent with the in-plane symmetry of the MgO layer observed by in situ reflective high electron energy diffraction. The in-plane epitaxial relationship of BST, MgO, and ZnO has been determined to be BST [110]//MgO [110]//ZnO [1120]more » and BST [110]/MgO [110]//ZnO [1100]. Capacitance-voltage measurements performed on BST coplanar interdigitated capacitor structures revealed a high dielectric tunability of up to 84% at 1 MHz.« less

Synthesis of bimetallic nanostructures by nanosecond laser ablation of multicomponent thin films in water

NASA Astrophysics Data System (ADS)

Nikov, R. G.; Nedyalkov, N. N.; Atanasov, P. A.; Karashanova, D. B.

2018-03-01

The paper presents results on nanosecond laser ablation of thin films immersed in a liquid. The thin films were prepared by consecutive deposition of layers of different metals by thermal evaporation (first layer) and classical on-axis pulsed laser deposition (second layer); Ni/Au, Ag/Au and Ni/Ag thin films were thus deposited on glass substrates. The as-prepared films were then placed at the bottom of a glass vessel filled with double distilled water and irradiated by nanosecond laser pulses delivered by a Nd:YAG laser system at λ = 355 nm. This resulted in the formation of colloids of the thin films’ material. We also compared the processes of ablation of a bulk target and a thin film in the liquid by irradiating a Au target and a Au thin film by the same laser wavelength and fluence (λ = 355 nm, F = 5 J/cm2). The optical properties of the colloids were evaluated by optical transmittance measurements in the UV– VIS spectral range. Transmission electron microscopy was employed to estimate the particles’ size distribution.

Formation of blade and slot die coated small molecule multilayers for OLED applications studied theoretically and by XPS depth profiling

NASA Astrophysics Data System (ADS)

Peters, Katharina; Raupp, Sebastian; Hummel, Helga; Bruns, Michael; Scharfer, Philip; Schabel, Wilhelm

2016-06-01

Slot die coaters especially designed for low material consumption and doctor blades were used to process small molecule solutions for organic light-emitting diodes (OLEDs). Optimum process parameters were developed for the large-scale coating techniques to generate stable single and multiple layers only a few nanometers thick. Achieving a multilayer architecture for solution-processed OLEDs is the most challenging step. X-ray photoelectron spectroscopy sputter depth profiling was performed to determine defined interfaces between coated organic layers. Commercially available small molecules NPB (N,N'-Di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine) and BAlq (Bis(8-hdroxy-2methylquinoline)-(4-phenylphenoxy)aluminum), originally developed for vacuum deposition, were used as hole, respectively electron transport material. Defined double-layers were processed with both scalable coating methods using the orthogonal solvent approach. The use of non-orthogonal solvents resulted in complete intermixing of the material. The results are explained by calculations of solubilities and simulating drying and diffusion kinetics of the small molecule solutions.

Ultralow power switching in a silicon-rich SiNy/SiNx double-layer resistive memory device.

PubMed

Kim, Sungjun; Chang, Yao-Feng; Kim, Min-Hwi; Bang, Suhyun; Kim, Tae-Hyeon; Chen, Ying-Chen; Lee, Jong-Ho; Park, Byung-Gook

2017-07-26

Here we demonstrate low-power resistive switching in a Ni/SiN y /SiN x /p ++ -Si device by proposing a double-layered structure (SiN y /SiN x ), where the two SiN layers have different trap densities. The LRS was measured to be as low as 1 nA at a voltage of 1 V, because the SiN x layer maintains insulating properties for the LRS. The single-layered device suffers from uncontrollability of the conducting path, accompanied by the inherent randomness of switching parameters, weak immunity to breakdown during the reset process, and a high operating current. On the other hand, for a double-layered device, the effective conducting path in each layer, which can determine the operating current, can be well controlled by the I CC during the initial forming and set processes. A one-step forming and progressive reset process is observed for a low-power mode, which differs from the high-power switching mode that shows a two-step forming and reset process. Moreover, nonlinear behavior in the LRS, whose origin can be attributed to the P-F conduction and F-N tunneling driven by abundant traps in the silicon-rich SiN x layer, would be beneficial for next-generation nonvolatile memory applications by using a conventional passive SiN x layer as an active dielectric.

Effect of double-layer application on dentin bond durability of one-step self-etch adhesives.

PubMed

Taschner, M; Kümmerling, M; Lohbauer, U; Breschi, L; Petschelt, A; Frankenberger, R

2014-01-01

The aim of this in vitro study was 1) to analyze the influence of a double-layer application technique of four one-step self-etch adhesive systems on dentin and 2) to determine its effect on the stability of the adhesive interfaces stored under different conditions. Four different one-step self-etch adhesives were selected for the study (iBondSE, Clearfil S(3) Bond, XenoV(+), and Scotchbond Universal). Adhesives were applied according to manufacturers' instructions or with a double-layer application technique (without light curing of the first layer). After bonding, resin-dentin specimens were sectioned for microtensile bond strength testing in accordance with the nontrimming technique and divided into 3 subgroups of storage: a) 24 hours (immediate bond strength, T0), b) six months (T6) in artificial saliva at 37°C, or c) five hours in 10 % NaOCl at room temperature. After storage, specimens were stressed to failure. Fracture mode was assessed under a light microscope. At T0, iBond SE showed a significant increase in microtensile bond strength when the double-application technique was applied. All adhesive systems showed reduced bond strengths after six months of storage in artificial saliva and after storage in 10% NaOCl for five hours; however at T6, iBond SE, Clearfil S(3) Bond, and XenoV(+) showed significantly higher microtensile bond strength results for the double-application technique compared with the single-application technique. Scotchbond Universal showed no difference between single- or double-application, irrespective of the storage conditions. The results of this study show that improvements in bond strength of one-step self-etch adhesives by using the double-application technique are adhesive dependent.

Sound transmission through stiffened double-panel structures lined with elastic porous materials

NASA Astrophysics Data System (ADS)

Mathur, Gopal P.; Tran, Boi N.; Bolton, J. S.; Shiau, Nae-Ming

This paper presents transmission loss prediction models for a periodically stiffened panel and stiffened double-panel structures using the periodic structure theory. The inter-panel cavity in the double-panels structures can be modeled as being separated by an airspace or filled with an elastic porous layer in various configurations. The acoustic behavior of elastic porous layer is described by a theory capable of accounting fully for multi-dimensional wave propagation in such materials. The predicted transmission loss of a single stiffened panel is compared with the measured data.

Gamma-telescopes Fermi/LAT and GAMMA-400 Trigger Systems Event Recognizing Methods Comparison

NASA Astrophysics Data System (ADS)

Arkhangelskaja, I. V.; Murchenko, A. E.; Chasovikov, E. N.; Arkhangelskiy, A. I.; Kheymits, M. D.

Usually instruments for high-energy γ-quanta registration consists of converter (where γ-quanta produced pairs) and calorimeter for particles energy measurements surrounded by anticoincidence shield used to events identification (whether incident particle was charged or neutral). The influence of pair formation by γ-quanta in shield and the backsplash (moved in the opposite direction particles created due high energy γ-rays interact with calorimeter) should be taken into account. It leads to decrease both effective area and registration efficiency at E>10 GeV. In the presented article the event recognizing methods used in Fermi/LAT trigger system is considered in comparison with the ones applied in counting and triggers signals formation system of gamma-telescope GAMMA-400. The GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the new high-apogee space γ-observatory. The GAMMA-400 consist of converter-tracker based on silicon-strip coordinate detectors interleaved with tungsten foils, imaging calorimeter make of 2 layers of double (x, y) silicon strip coordinate detectors interleaved with planes of CsI(Tl) crystals and the electromagnetic calorimeter CC2 consists only of CsI(Tl) crystals. Several plastics detections systems used as anticoincidence shield, for particles energy and moving direction estimations. The main differences of GAMMA-400 constructions from Fermi/LAT one are using the time-of-flight system with base of 50 cm and double layer structure of plastic detectors provides more effective particles direction definition and backsplash rejection. Also two calorimeters in GAMMA-400 composed the total absorbtion spectrometer with total thickness ∼ 25 X0 or ∼1.2 λ0 for vertical incident particles registration and 54 X0 or 2.5 λ0 for laterally incident ones (where λ0 is nuclear interaction length). It provides energy resolution 1-2% for 10 GeV-3.0×103 GeV events while the Fermi/LAT energy resolution does not reach such a value because of its calorimeter thickness is only ∼10 X0 and energy of registered particles is defined by shower profile analysis. Less than 3% photons will be wrongly recognized as electrons or protons in double-layer ACtop taking into account both temporal and amplitude trigger marker analysis methods during onboard processing in the counting and triggers signals formation system of GAMMA-400. The proton rejection factor will be ∼10-5. The Fermi/LAT based on a 4 × 4 array of identical towers each contains a tracker, calorimeter and data acquisition module. Each tracker consists of 18 x-y silicon-strip layers. The calorimeter in each tower made of eight layers in a hodoscopic arrangement for measure the three-dimensional profiles of showers permits corrections for energy leakage and enhances the capability to discriminate hadronic cosmic rays. The each layer consists of 12 CsI(Tl) based bars. The segmented anticoincidence shield covers the array of towers. Unfortunately, several types of biases lead to systematic effects caused high values of relative systematic uncertainties of the exposure, the number of signal events, the induced fractional signal and so on. For example non confirmed announcement of ∼133 GeV line detection and lost sources in different Fermi catalogues (1FGL, 2FGL, 3FGL) - just well seen in 2FGL Cygnus X-3 (J2032.1+4049) does not appear in 3FGL. It allows to conclude sufficient biases in LAT characteristics obtained methods and event recognized algorithms. Now Fermi/LAT operates during ∼ 7 years but effective caveats methods continuously to be proposed. Respectively, continuation of measurements with use of other telescopes is necessary, and realization of GAMMA-400 will allow improving the results.

Methane Hydrate Formation in Thick Sand Reservoirs: Long-range Gas Transport or Short-range Methane Diffusion?

NASA Astrophysics Data System (ADS)

You, K.; Flemings, P. B.

2016-12-01

We developed two 2-D numerical models to simulate hydrate formation by long range methane gas transport and short-range methane diffusion. We interpret that methane hydrates in thick sands are most likely formed by long range gas transport where methane gas is transported upward into the hydrate stability zone (HSZ) under buoyancy and locally forms hydrate to its stability limit. In short-range methane diffusion, methane is generated locally by biodegradation of organic matter in mud and diffused into bounding sands where it forms hydrate. We could not simulate enough methane transport by diffusion to account for its observed concentration in thick sands. In our models, we include the capillary effect on dissolved methane solubility and on the hydrate phase boundary, sedimentation and different compaction in sand and mud, fracture generation as well as the fully coupled multiphase flow and multicomponent transport. We apply our models to a 12 meter-thick hydrate-bearing sand layer at Walker Ridge 313, Northern Gulf of Mexico. With the long-range gas transport, hydrate saturation is greater than 90% and salinity is increased from seawater to about 8 wt.% through the entire sand. With short-range diffusion, hydrate saturation is more than 90% at the sand base and is less than 10% in the overlying section; salinity is close to seawater when sand is deposited to 800 meter below seafloor by short-range methane diffusion. With short-range diffusion, the amount of hydrate formed is much less than that interpreted from the well log data. Two transient gas layers separated by a hydrate layer are formed from short-range diffusion caused by capillary effect. This could be interpreted as a double bottom simulating reflector. This study provides further insights into different hydrate formation mechanisms, and could serve as a base to confirm the hydrate formation mechanism in fields.

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

Ghosh, Soumya; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

Electron transfer and proton coupled electron transfer (PCET) reactions at electrochemical interfaces play an essential role in a broad range of energy conversion processes. The reorganization energy, which is a measure of the free energy change associated with solute and solvent rearrangements, is a key quantity for calculating rate constants for these reactions. We present a computational method for including the effects of the double layer and ionic environment of the diffuse layer in calculations of electrochemical solvent reorganization energies. This approach incorporates an accurate electronic charge distribution of the solute within a molecular-shaped cavity in conjunction with a dielectricmore » continuum treatment of the solvent, ions, and electrode using the integral equations formalism polarizable continuum model. The molecule-solvent boundary is treated explicitly, but the effects of the electrode-double layer and double layer-diffuse layer boundaries, as well as the effects of the ionic strength of the solvent, are included through an external Green’s function. The calculated total reorganization energies agree well with experimentally measured values for a series of electrochemical systems, and the effects of including both the double layer and ionic environment are found to be very small. This general approach was also extended to electrochemical PCET and produced total reorganization energies in close agreement with experimental values for two experimentally studied PCET systems. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.« less

Organic light emitting device having multiple separate emissive layers

DOEpatents

Forrest, Stephen R [Ann Arbor, MI

2012-03-27

An organic light emitting device having multiple separate emissive layers is provided. Each emissive layer may define an exciton formation region, allowing exciton formation to occur across the entire emissive region. By aligning the energy levels of each emissive layer with the adjacent emissive layers, exciton formation in each layer may be improved. Devices incorporating multiple emissive layers with multiple exciton formation regions may exhibit improved performance, including internal quantum efficiencies of up to 100%.

Purse-string double-layer closure: a novel technique for repairing the uterine incision during cesarean section.

PubMed

Turan, Cem; Büyükbayrak, Esra Esim; Yilmaz, Aylin Onan; Karsidag, Yasemin Karageyim; Pirimoglu, Meltem

2015-04-01

To compare the classical double-layer uterine closure to a double-layer purse-string uterine closure (Turan technique) in cesarean section regarding short- and long-term results. Patients were randomized into either the double-layer purse-string uterine closure arm (study group, 84 patients) or the classical double-layer uterine closure arm (control group, 84 patients). For short-term comparison, a detailed transvaginal ultrasound examination was planned in all patients 6 weeks after the operation and a wedge-shaped defect in the uterine incision scar was accepted as uterine scar defect and recorded. For the long-term comparison, subsequent pregnancies of these patients were followed up for any complication. The number of patients with ultrasonographically visible uterine scar defect was 12 (23.5% of all scar defects) in the study group whereas it was 39 (76.5% of all scar defects) in the control group (P < 0.001, χ(2) = 15.42). Demographic data, operation time, hospitalization time, preoperative and postoperative hemoglobin values were not significantly different between the groups. During the 2-year of the follow-up period, five patients in the study group and six patients in the control group became pregnant again. No complication during their pregnancies and second cesarean operation were encountered. With the Turan technique, the uterine incision length becomes shorter, and the frequency of uterine scar defect is lower regarding short-term results. More data is needed for long-term results. ClinicalTrials.gov NCT01287611. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.

Double-layered PTFE-covered nitinol stents: experience in 32 patients with malignant esophageal strictures.

PubMed

Park, Jung Gu; Jung, Gyoo-Sik; Oh, Kyung Seung; Park, Seon-Ja

2010-08-01

We evaluated the effectiveness of a double-layered polytetrafluoroethylene (PTFE)-covered nitinol stent in the palliative treatment of malignant esophageal strictures. A double-layered PTFE-covered nitinol stent was designed to reduce the propensity to migration of conventional covered stent. The stent consists of an inner PTFE-covered stent and an outer uncovered nitinol stent tube. With fluoroscopic guidance, the stent was placed in 32 consecutive patients with malignant esophageal strictures. During the follow-up period, the technical and clinical success rates, complications, and cumulative patient survival and stent patency were evaluated. Stent placement was technically successful in all patients, and no procedural complications occurred. After stent placement, the symptoms of 30 patients (94%) showed improvement. During the mean follow-up of 103 days (range, 9-348 days), 11 (34%) of 32 patients developed recurrent symptoms due to tumor overgrowth in five patients (16%), tumor ingrowth owing to detachment of the covering material (PTFE) apart from the stent wire in 3 (9%), mucosal hyperplasia in 2 (6%), and stent migration in 1 (3%). Ten of these 11 patients were treated by means of placing a second covered stent. Thirty patients died, 29 as a result of disease progression and 1 from aspiration pneumonia. The median survival period was 92 days. The median period of primary stent patency was 190 days. The double-layered PTFE-covered nitinol stent seems to be effective for the palliative treatment of malignant esophageal strictures. We believe that the double-layer configuration of this stent can contribute to decreasing the stent's migration rate.

Design rules and reality check for carbon-based ultracapacitors

NASA Astrophysics Data System (ADS)

Eisenmann, Erhard T.

1995-04-01

Design criteria for carbon-based Ultracapacitors have been determined for specified energy and power requirements, using the geometry of the components and such material properties as density, porosity and conductivity as parameters, while also considering chemical compatibility. This analysis shows that the weights of active and inactive components of the capacitor structure must be carefully balanced for maximum energy and power density. When applied to nonaqueous electrolytes, the design rules for a 5 Wh/kg device call for porous carbon with a specific capacitance of about 30 F/cu cm. This performance is not achievable with pure, electrostatic double layer capacitance. Double layer capacitance is only 5 to 30% of that observed in aqueous electrolyte. Tests also showed that nonaqueous electrolytes have a diminished capability to access micropores in activated carbon, in one case yielding a capacitance of less than 1 F/cu cm for carbon that had 100 F/cu cm in aqueous electrolyte. With negative results on nonaqueous electrolytes dominating the present study, the obvious conclusion is to concentrate on aqueous systems. Only aqueous double layer capacitors offer adequate electrostatic charging characteristics which is the basis for high power performance. There arc many opportunities for further advancing aqueous double layer capacitors, one being the use of highly activated carbon films, as opposed to powders, fibers and foams. While the manufacture of carbon films is still costly, and while the energy and power density of the resulting devices may not meet the optimistic goals that have been proposed, this technology could produce true double layer capacitors with significantly improved performance and large commercial potential.

Tectonic plates, D (double prime) thermal structure, and the nature of mantle plumes

NASA Technical Reports Server (NTRS)

Lenardic, A.; Kaula, W. M.

1994-01-01

It is proposed that subducting tectonic plates can affect the nature of thermal mantle plumes by determining the temperature drop across a plume source layer. The temperature drop affects source layer stability and the morphology of plumes emitted from it. Numerical models are presented to demonstrate how introduction of platelike behavior in a convecting temperature dependent medium, driven by a combination of internal and basal heating, can increase the temperature drop across the lower boundary layer. The temperature drop increases dramatically following introduction of platelike behavior due to formation of a cold temperature inversion above the lower boundary layer. This thermal inversion, induced by deposition of upper boundary layer material to the system base, decays in time, but the temperature drop across the lower boundary layer always remains considerably higher than in models lacking platelike behavior. On the basis of model-inferred boundary layer temperature drops and previous studies of plume dynamics, we argue that generally accepted notions as to the nature of mantle plumes on Earth may hinge on the presence of plates. The implication for Mars and Venus, planets apparently lacking plate tectonics, is that mantle plumes of these planets may differ morphologically from those of Earth. A corollary model-based argument is that as a result of slab-induced thermal inversions above the core mantle boundary the lower most mantle may be subadiabatic, on average (in space and time), if major plate reorganization timescales are less than those acquired to diffuse newly deposited slab material.

Gain enhancement with near-zero-index metamaterial superstrate

NASA Astrophysics Data System (ADS)

Bouzouad, M.; Chaker, S. M.; Bensafielddine, D.; Laamari, E. M.

2015-11-01

The objective of this paper was to use a near-zero-index ( n) metamaterial as a single- or a double-layer superstrate suspended above a microstrip patch antenna, operating at 43 GHz, for the gain enhancement. The single metamaterial layer superstrate consists of a periodic arrangement of Jerusalem cross unit cells and behaves as an homogeneous medium characterized by a refractive index close to zero. This metamaterial property allows gathering radiated waves from the antenna and collimates them toward the superstrate normal direction. The proposed design improves the antenna gain by 5.1 dB with the single-layer superstrate and 7 dB with the double-layer superstrate.

Numerical modeling of heat transfer during hydrogen absorption in thin double-layered annular ZrCo beds

NASA Astrophysics Data System (ADS)

Cui, Yehui; Zeng, Xiangguo; Kou, Huaqin; Ding, Jun; Wang, Fang

2018-06-01

In this work a three-dimensional (3D) hydrogen absorption model was proposed to study the heat transfer behavior in thin double-layered annular ZrCo beds. Numerical simulations were performed to investigate the effects of conversion layer thickness, thermal conductivity, cooling medium and its flow velocity on the efficiency of heat transfer. Results reveal that decreasing the layer thickness and improving the thermal conductivity enhance the ability of heat transfer. Compared with nitrogen and helium, water appears to be a better medium for cooling. In order to achieve the best efficiency of heat transfer, the flow velocity needs to be maximized.

Enhanced 630nm equatorial airglow emission observed by Limb Viewing Hyper Spectral Imager (LiVHySI) onboard YOUTHSAT-1

NASA Astrophysics Data System (ADS)

Bisht, R. S.; Thapa, N.; Babu, P. N.

2016-04-01

The Earth's airglow layer, when observed in the limb view mode, appears to be a double layer. LiVHySI onboard YOUTHSAT (inclination 98.730, apogee 817 km, launched by Indian Space Research Organization in April, 2011) is an Earth's limb viewing camera measuring airglow emissions in the spectral window of 550-900 nm. Total altitude coverage is about 500 km with command selectable lowest altitude. During few of the orbits we have observed the double layer structure and obtained absolute spectral intensity and altitude profile for 630 nm airglow emission. Our night time observations of upper atmosphere above dip equator carried out on 3rd May, 2011 show a prominent 630 nm double layer structure. The upper airglow layer consists of the 630 nm atomic oxygen O(1D) emission line and lower layer consists of OH(9-3) meinel band emission at 630 nm. The volume emission rate as a function of altitude is simulated for our observational epoch and the modeled limb intensity distribution is compared with the observations. The observations are in good agreement with the simulated intensity distribution.

Layered Halide Double Perovskites Cs3+nM(II)nSb2X9+3n (M = Sn, Ge) for Photovoltaic Applications.

PubMed

Tang, Gang; Xiao, Zewen; Hosono, Hideo; Kamiya, Toshio; Fang, Daining; Hong, Jiawang

2018-01-04

Over the past few years, the development of lead-free and stable perovskite absorbers with excellent performance has attracted extensive attention. Much effort has been devoted to screening and synthesizing this type of solar cell absorbers. Here, we present a general design strategy for designing the layered halide double perovskites Cs 3+n M(II) n Sb 2 X 9+3n (M = Sn, Ge) with desired photovoltaic-relevant properties by inserting [MX 6 ] octahedral layers, based on the principles of increased electronic dimensionality. Compared to Cs 3 Sb 2 I 9 , more suitable band gaps, smaller carrier effective masses, larger dielectric constants, lower exciton binding energies, and higher optical absorption can be achieved by inserting variable [SnI 6 ] or [GeI 6 ] octahedral layers into the [Sb 2 I 9 ] bilayers. Moreover, our results show that adjusting the thickness of inserted octahedral layers is an effective approach to tune the band gaps and carrier effective masses in a large range. Our work provides useful guidance for designing the promising layered antimony halide double perovskite absorbers for photovoltaic applications.

Preparation of PLGA/Rose Bengal colloidal particles by double emulsion and layer-by-layer for breast cancer treatment.

PubMed

Loya-Castro, María F; Sánchez-Mejía, Mariana; Sánchez-Ramírez, Dante R; Domínguez-Ríos, Rossina; Escareño, Noé; Oceguera-Basurto, Paola E; Figueroa-Ochoa, Édgar B; Quintero, Antonio; Del Toro-Arreola, Alicia; Topete, Antonio; Daneri-Navarro, Adrián

2018-05-15

The use of colloidal particles (CPs) in the transport of drugs is developing rapidly thanks to its effectiveness and biosafety, especially in the treatment of various types of cancer. In this study Rose Bengal/PLGA CPs synthesized by double emulsion (W/O/W) and by electrostatic adsorption (layer-by-layer), were characterized and evaluated as potential breast cancer treatment. CPs were evaluated in terms of size, zeta potential, drug release kinetics and cell viability inhibition efficacy with the triple negative breast cancer cell line HCC70. The results showed that both types of CPs can be an excellent alternative to conventional cancer treatment by taking advantage of the enhanced permeation and retention (EPR) effect, manifested by solid tumors; however, the double emulsion CPs showed more suitable delivery times of up to 60% within two days, while layer-by-layer showed fast release of 50% in 90 min. Both types of CPs were capable to decrease cell viability, which encourage us to further testing in in vivo models to prove their efficacy and feasible use in the treatment of triple negative breast cancer. Copyright © 2018 Elsevier Inc. All rights reserved.

Permanent Magnet Synchronous Motor Driven by PWM Inverter with Voltage Booster with Regenerating Capability Augmented by Double-Layer Capacitor

NASA Astrophysics Data System (ADS)

Yamamoto, Kichiro; Shinohara, Katsuji; Furukawa, Shinya

An interior permanent magnet (IPM) motor drive system which has regenerating capability augmented by double-layer capacitors is proposed. The motor is driven by a PWM inverter with voltage booster. The voltage booster is used to control the dc link voltage in high speed region to improve the system efficiency. Furthermore, the double-layer capacitor as a storage element is combined with the PWM inverter with voltage booster to gain the efficiency for the regenerating operation. In this system, normally, the regenerative power does not return to a battery directly but is stored in the double-layer capacitors for the next motoring action to suppress the excessive regenerative current to battery, and the regenerative power returns to the battery when the regenerative energy is larger than a certain value. The charging current to the battery is controlled to a constant value to extend the life-time of the battery. The transient and steady state characteristics of the system for 1.5kW IPM motor are investigated by both simulation and experiment. Finally, the effectiveness of the system is demonstrated by the simulated and experimental results.

Organic double layer element driven by triboelectric nanogenerator: Study of carrier behavior by non-contact optical method

NASA Astrophysics Data System (ADS)

Chen, Xiangyu; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2016-02-01

By using optical electric-field-induced second-harmonic generation (EFISHG) technique, we studied carrier behavior caused by contact electrification (CE) in an organic double-layer element. This double-layer sample was half suspended in the open air, where one electrode (anode or cathode) was connected with a Cu foil for electrification while the other electrode was floated. Results showed two distinct carrier behaviors, depending on the (anode or cathode) connections to the Cu foil, and these carrier behaviors were analyzed based on the Maxwell-Wagner model. The double-layer sample works as a simple solar cell device. The photovoltaic effect and CE process have been proved to be two paralleled effects without strong interaction with each other, while photoconductivity changing in the sample can enhance the relaxation of CE induced charges. By probing the carrier behavior in this half-suspended device, the EFISHG technique has been demonstrated to be an effective non-contact method for clarifying the CE effect on related energy harvesting devices and electronics devices. Meanwhile, the related physical analysis in this letter is also useful for elucidating the fundamental characteristic of hybrid energy system based on solar cell and triboelectric nanogenerator.

Pseudocapacitive and hierarchically ordered porous electrode materials supercapacitors

NASA Astrophysics Data System (ADS)

Saruhan, B.; Gönüllü, Y.; Arndt, B.

2013-05-01

Commercially available double layer capacitors store energy in an electrostatic field. This forms in the form of a double layer by charged particles arranged on two electrodes consisting mostly of active carbon. Such double layer capacitors exhibit a low energy density, so that components with large capacity according to large electrode areas are required. Our research focuses on the development of new electrode materials to realize the production of electrical energy storage systems with high energy density and high power density. Metal oxide based electrodes increase the energy density and the capacitance by addition of pseudo capacitance to the static capacitance present by the double layer super-capacitor electrodes. The so-called hybrid asymmetric cell capacitors combine both types of energy storage in a single component. In this work, the production routes followed in our laboratories for synthesis of nano-porous and aligned metal oxide electrodes using the electrochemical and sputter deposition as well as anodization methods will be described. Our characterisation studies concentrate on electrodes having redox metal-oxides (e.g. MnOx and WOx) and hierarchically aligned nano-porous Li-doped TiO2-NTs. The material specific and electrochemical properties achieved with these electrodes will be presented.

Repair of Inaccessible Ventral Dural Defect in Thoracic Spine: Double Layered Duraplasty

PubMed Central

Lee, Dong-Hyun; Park, Jeong-Ill; Park, Ki-Su; Cho, Dae-Chul; Sung, Joo-Kyung

2016-01-01

We propose a double layered (intradural and epidural patch) duraplasty that utilizes Lyoplant and Duraseal. We examined a 47-year-old woman after decompression for thoracic ossification of posterior longitudinal ligament was performed in another hospital. On postoperative day 7, she complained of weakness in both legs. Postoperative magnetic resonance imaging (MRI) showed cerebrospinal fluid (CSF) collection with cord compression. In the operative field, we found 2 large dural defects on the ventral dura mater. We performed a conventional fat graft with fibrin glue. However, the patient exhibited neurologic deterioration, and a postoperative MRI again showed CSF collection. We performed dorsal midline durotomy and inserted a intradural and epidural Lyoplant patch. She immediately experienced diminishing back pain postoperatively. Her visual analog scale and motor power improved markedly. Postoperative MRIs performed at 2 and 16 months showed no spinal cord compression or CSF leakage to the epidural space. We describe a new technique for double layered duraplasty. Although we do not recommend this technique for all dural repairs, double-layered duraplasty may be useful for repairing large inaccessible dural tears in cases of persistent CSF leakage refractory to conventional management. PMID:27437022

Intracavity double diode structures with GaInP barrier layers for thermophotonic cooling

NASA Astrophysics Data System (ADS)

Tiira, Jonna; Radevici, Ivan; Haggren, Tuomas; Hakkarainen, Teemu; Kivisaari, Pyry; Lyytikäinen, Jari; Aho, Arto; Tukiainen, Antti; Guina, Mircea; Oksanen, Jani

2017-02-01

Optical cooling of semiconductors has recently been demonstrated both for optically pumped CdS nanobelts and for electrically injected GaInAsSb LEDs at very low powers. To enable cooling at larger power and to understand and overcome the main obstacles in optical cooling of conventional semiconductor structures, we study thermophotonic (TPX) heat transport in cavity coupled light emitters. Our structures consist of a double heterojunction (DHJ) LED with a GaAs active layer and a corresponding DHJ or a p-n-homojunction photodiode, enclosed within a single semiconductor cavity to eliminate the light extraction challenges. Our presently studied double diode structures (DDS) use GaInP barriers around the GaAs active layer instead of the AlGaAs barriers used in our previous structures. We characterize our updated double diode structures by four point probe IV- measurements and measure how the material modifications affect the recombination parameters and coupling quantum efficiencies in the structures. The coupling quantum efficiency of the new devices with InGaP barrier layers is found to be approximately 10 % larger than for the structures with AlGaAs barriers at the point of maximum efficiency.

Sol-gel-Derived nano-sized double layer anti-reflection coatings (SiO2/TiO2) for low-cost solar cell fabrication.

PubMed

Lee, Seung Jun; Hur, Man Gyu; Yoon, Dae Ho

2013-11-01

We investigate nano-sized double layer anti-reflection coatings (ARCs) using a TiO2 and SiO2 sol-gel solution process for mono-crystalline silicon solar cells. The process can be easily adapted for spraying sol-gel coatings to reduce manufacturing cost. The spray-coated SiO2/TiO2 nano-sized double layer ARCs were deposited on mono-crystalline silicon solar cells, and they showed good optical properties. The spray coating process is a lower-cost fabrication process for large-scale coating than vacuum deposition processes such as PECVD. The measured average optical reflectance (300-1200 nm) was about approximately 8% for SiO2/TiO2 nano-sized double layer ARCs. The electrical parameters of a mono-crystalline silicon solar cell and reflection losses show that the SiO2/TiO2 stacks can improve cell efficiency by 0.2% compared to a non-coated mono-crystalline silicon solar cell. In the results, good correlation between theoretical and experimental data was obtained. We expect that the sol-gel spray-coated mono-crystalline silicon solar cells have high potential for low-cost solar cell fabrication.

Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics.

PubMed

Munje, Rujuta D; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

2015-09-30

An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics

NASA Astrophysics Data System (ADS)

Munje, Rujuta D.; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

2015-09-01

An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

Synthesis, characterization, and efficacy of antituberculosis isoniazid zinc aluminum-layered double hydroxide based nanocomposites

PubMed Central

Saifullah, Bullo; El Zowalaty, Mohamed Ezzat; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin Mahler; Hussein, Mohd Zobir

2016-01-01

The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly. PMID:27486322

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

Verheest, Frank, E-mail: frank.verheest@ugent.be; School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000; Hellberg, Manfred A., E-mail: hellberg@ukzn.ac.za

The propagation of arbitrary amplitude electron-acoustic solitons and double layers is investigated in a plasma containing cold positive ions, cool adiabatic and hot isothermal electrons, with the retention of full inertial effects for all species. For analytical tractability, the resulting Sagdeev pseudopotential is expressed in terms of the hot electron density, rather than the electrostatic potential. The existence domains for Mach numbers and hot electron densities clearly show that both rarefactive and compressive solitons can exist. Soliton limitations come from the cool electron sonic point, followed by the hot electron sonic point, until a range of rarefactive double layers occurs.more » Increasing the relative cool electron density further yields a switch to compressive double layers, which ends when the model assumptions break down. These qualitative results are but little influenced by variations in compositional parameters. A comparison with a Boltzmann distribution for the hot electrons shows that only the cool electron sonic point limit remains, giving higher maximum Mach numbers but similar densities, and a restricted range in relative hot electron density before the model assumptions are exceeded. The Boltzmann distribution can reproduce neither the double layer solutions nor the switch in rarefactive/compressive character or negative/positive polarity.« less

Li + Defects in a Solid-State Li Ion Battery: Theoretical Insights with a Li 3 OCl Electrolyte

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

Stegmaier, Saskia; Voss, Johannes; Reuter, Karsten

In a solid-state Li ion battery, the solid-state electrolyte exits principally in regions of high externally applied potentials, and this varies rapidly at the interfaces with electrodes due to the formation of electrochemical double layers. Here, we investigate the implications of these for a model solid-state Li ion battery Li|Li 3OCl|C, where C is simply a metallic intercalation cathode. We use DFT to calculate the potential dependence of the formation energies of the Li + charge carriers in superionic Li 3OCl. We find that Li+ vacancies are the dominant species at the cathode while Li+ interstitials dominate at the anode.more » With typical Mg aliovalent doping of Li 3OCl, Li + vacancies dominate the bulk of the electrolyte as well, with freely mobile vacancies only ~ 10 -4 of the Mg doping density at room temperature. We study the repulsive interaction between Li+ vacancies and find that this is extremely short range, typically only one lattice constant due to local structural relaxation around the vacancy and this is significantly shorter than pure electrostatic screening. We model a Li 3OCl- cathode interface by treating the cathode as a nearly ideal metal using a polarizable continuum model with an ε r = 1000. There is a large interface segregation free energy of ~ - 1 eV per Li + vacancy. Combined with the short range for repulsive interactions of the vacancies, this means that very large vacancy concentrations will build up in a single layer of Li 3OCl at the cathode interface to form a compact double layer. The calculated potential drop across the interface is ~ 3 V for a nearly full concentration of vacancies at the surface. This suggests that nearly all the cathode potential drop in Li 3OCl occurs at the Helmholtz plane rather than in a diffuse space-charge region. We suggest that the conclusions found here will be general to other superionic conductors as well.« less

Li + Defects in a Solid-State Li Ion Battery: Theoretical Insights with a Li 3 OCl Electrolyte

DOE PAGES

Stegmaier, Saskia; Voss, Johannes; Reuter, Karsten; ...

2017-04-26

In a solid-state Li ion battery, the solid-state electrolyte exits principally in regions of high externally applied potentials, and this varies rapidly at the interfaces with electrodes due to the formation of electrochemical double layers. Here, we investigate the implications of these for a model solid-state Li ion battery Li|Li 3OCl|C, where C is simply a metallic intercalation cathode. We use DFT to calculate the potential dependence of the formation energies of the Li + charge carriers in superionic Li 3OCl. We find that Li+ vacancies are the dominant species at the cathode while Li+ interstitials dominate at the anode.more » With typical Mg aliovalent doping of Li 3OCl, Li + vacancies dominate the bulk of the electrolyte as well, with freely mobile vacancies only ~ 10 -4 of the Mg doping density at room temperature. We study the repulsive interaction between Li+ vacancies and find that this is extremely short range, typically only one lattice constant due to local structural relaxation around the vacancy and this is significantly shorter than pure electrostatic screening. We model a Li 3OCl- cathode interface by treating the cathode as a nearly ideal metal using a polarizable continuum model with an ε r = 1000. There is a large interface segregation free energy of ~ - 1 eV per Li + vacancy. Combined with the short range for repulsive interactions of the vacancies, this means that very large vacancy concentrations will build up in a single layer of Li 3OCl at the cathode interface to form a compact double layer. The calculated potential drop across the interface is ~ 3 V for a nearly full concentration of vacancies at the surface. This suggests that nearly all the cathode potential drop in Li 3OCl occurs at the Helmholtz plane rather than in a diffuse space-charge region. We suggest that the conclusions found here will be general to other superionic conductors as well.« less

Carrier mobility and scattering lifetime in electric double-layer gated few-layer graphene

NASA Astrophysics Data System (ADS)

Piatti, E.; Galasso, S.; Tortello, M.; Nair, J. R.; Gerbaldi, C.; Bruna, M.; Borini, S.; Daghero, D.; Gonnelli, R. S.

2017-02-01

We fabricate electric double-layer field-effect transistor (EDL-FET) devices on mechanically exfoliated few-layer graphene. We exploit the large capacitance of a polymeric electrolyte to study the transport properties of three, four and five-layer samples under a large induced surface charge density both above and below the glass transition temperature of the polymer. We find that the carrier mobility shows a strong asymmetry between the hole and electron doping regime. We then employ ab initio density functional theory (DFT) calculations to determine the average scattering lifetime from the experimental data. We explain its peculiar dependence on the carrier density in terms of the specific properties of the electrolyte we used in our experiments.

The effect of a nonmagnetic cap layer on the spin-polarized tunneling and magnetoresistance in double-barrier planar junctions

NASA Astrophysics Data System (ADS)

Xie, Zheng-Wei; Li, Bo-Zang; Li, Yu-Xian

2003-10-01

Within the framework of the free-electron model, the tunneling magnetoresistance (TMR) and tunneling conductance (TC) in double magnetic tunnel junctions (DMTJ) with nonmagnetic cap layer, i.e. the NM/FM/I/NM/(FM)/I/FM/NM junction is investigated. FM, NM and I represent the ferromagnetic metal, nonmagnetic metal and insulator, respectively, NM(FM) indicates that the middle layer can be NM or FM. Our results show that, due to the spin-dependent interfacial potential barriers, the influences of the thickness of the FM layer on TC and TMR in DMTJ are large, and when the thicknesses of these two FM layers are suitable a large TMR can be obtained. (

Double layer field shaping systems for toroidal plasmas

DOEpatents

Ohyabu, Nobuyoshi

1982-01-01

Methods and apparatus for plasma generation, confinement and control such as Tokamak plasma systems are described having a two layer field shaping coil system comprising an inner coil layer close to the plasma and an outer coil layer to minimize the current in the inner coil layer.

Development of organic-inorganic double hole-transporting material for high performance perovskite solar cells

NASA Astrophysics Data System (ADS)

Jo, Jea Woong; Seo, Myung-Seok; Jung, Jae Woong; Park, Joon-Suh; Sohn, Byeong-Hyeok; Ko, Min Jae; Son, Hae Jung

2018-02-01

The control of the optoelectronic properties of the interlayers of perovskite solar cells (PSCs) is crucial for achieving high photovoltaic performances. Of the solution-processable interlayer candidates, NiOx is considered one of the best inorganic hole-transporting layer (HTL) materials. However, the power conversion efficiencies (PCEs) of NiOx-based PSCs are limited by the unfavorable contact between perovskite layers and NiOx HTLs, the high density of surface trap sites, and the inefficient charge extraction from perovskite photoactive layers to anodes. Here, we introduce a new organic-inorganic double HTL consisting of a Cu:NiOx thin film passivated by a conjugated polyelectrolyte (PhNa-1T) film. This double HTL has a significantly lower pinhole density and forms better contact with perovskite films, which results in enhanced charge extraction. As a result, the PCEs of PSCs fabricated with the double HTL are impressively improved up to 17.0%, which is more than 25% higher than that of the corresponding PSC with a Cu:NiOx HTL. Moreover, PSCs with the double HTLs exhibit similar stabilities under ambient conditions to devices using inorganic Cu:NiOx. Therefore, this organic-inorganic double HTL is a promising interlayer material for high performance PSCs with high air stability.

Rapid prototyping of a double-layer polyurethane-collagen conduit for peripheral nerve regeneration.

PubMed

Cui, Tongkui; Yan, Yongnian; Zhang, Renji; Liu, Li; Xu, Wei; Wang, Xiaohong

2009-03-01

A new technique for preparing double-layer polyurethane (PU)-collagen nerve conduits for peripheral nerve repair via a double-nozzle, low-temperature, deposition manufacturing (DLDM) system has been developed. The DLDM system is based on a digital prototyping approach, and uses a combination of thermally induced phase separation and freeze-drying. With this system, two kinds of biomaterials with different properties can be combined to produce scaffold structures with good biocompatibility in the inner layer and with the desired mechanical strength protruded by the outer. The forming precision is high, the wall thickness can be controlled, and a tight connection between the two layers can be achieved. The effects of changing the processing parameters and the material temperature on the structure of the scaffolds have been investigated. Additionally, the effect of material concentration on the mechanical strength and hydrophilic properties of the scaffolds has also been studied. Ideal peripheral nerve repair conduits, comprising an outer microporous layer of PU and internal oriented filaments of collagen, have been manufactured through optimizing the processing parameters and the biomaterial concentrations.

Improved Mechanical Compatibility and Cytocompatibility of Ta/Ti Double-Layered Composite Coating

NASA Astrophysics Data System (ADS)

Ding, Ding; Xie, Youtao; Li, Kai; Huang, Liping; Zheng, Xuebin

2017-08-01

In order to improve the mechanical compatibility and cytocompatibility of titanium implants, a composite coating with double layers composed of tantalum and titanium was designed and prepared using plasma spraying technology. In the composite coating, the upper tantalum layer provides a good biocompatibility, and the sublayer of titanium with a porous structure ensures the low elastic modulus. Results show that the fabricated composite coating exhibits a relatively low elastic modulus of 26.7 GPa, which is close to the elastic modulus of human cortical bone. In vitro cytocompatibility evaluation of the composite coating shows that the human bone marrow stromal cells exhibit enhanced adhesion and spreading performance on the double-layered composite coating in comparison with the single-layered titanium coating. In order to eliminate the misgivings of chemical stability of the composite coating in clinical application, electrochemical corrosion of the coating was examined. The results obtained revealed a very weak galvanic corrosion between the tantalum and titanium in the composite coating, which would ensure the safety of the coating in vivo.

Sound transmission through finite lightweight multilayered structures with thin air layers.

PubMed

Dijckmans, A; Vermeir, G; Lauriks, W

2010-12-01

The sound transmission loss (STL) of finite lightweight multilayered structures with thin air layers is studied in this paper. Two types of models are used to describe the vibro-acoustic behavior of these structures. Standard transfer matrix method assumes infinite layers and represents the plane wave propagation in the layers. A wave based model describes the direct sound transmission through a rectangular structure placed between two reverberant rooms. Full vibro-acoustic coupling between rooms, plates, and air cavities is taken into account. Comparison with double glazing measurements shows that this effect of vibro-acoustic coupling is important in lightweight double walls. For infinite structures, structural damping has no significant influence on STL below the coincidence frequency. In this frequency region, the non-resonant transmission or so-called mass-law behavior dominates sound transmission. Modal simulations suggest a large influence of structural damping on STL. This is confirmed by experiments with double fiberboard partitions and sandwich structures. The results show that for thin air layers, the damping induced by friction and viscous effects at the air gap surfaces can largely influence and improve the sound transmission characteristics.

Electric Double Layer Composed of an Antagonistic Salt in an Aqueous Mixture: Local Charge Separation and Surface Phase Transition

NASA Astrophysics Data System (ADS)

Yabunaka, Shunsuke; Onuki, Akira

2017-09-01

We examine an electric double layer containing an antagonistic salt in an aqueous mixture, where the cations are small and hydrophilic but the anions are large and hydrophobic. In this situation, a strong coupling arises between the charge density and the solvent composition. As a result, the anions are trapped in an oil-rich adsorption layer on a hydrophobic wall. We then vary the surface charge density σ on the wall. For σ >0 the anions remain accumulated, but for σ <0 the cations are attracted to the wall with increasing |σ |. Furthermore, the electric potential drop Ψ (σ ) is nonmonotonic when the solvent interaction parameter χ (T ) exceeds a critical value χc determined by the composition and the ion density in the bulk. This leads to a first-order phase transition between two kinds of electric double layers with different σ and common Ψ . In equilibrium such two-layer regions can coexist. The steric effect due to finite ion sizes is crucial in these phenomena.

Selectivity Enhancement by Using Double-Layer MOX-Based Gas Sensors Prepared by Flame Spray Pyrolysis (FSP).

PubMed

Rebholz, Julia; Grossmann, Katharina; Pham, David; Pokhrel, Suman; Mädler, Lutz; Weimar, Udo; Barsan, Nicolae

2016-09-06

Here we present a novel concept for the selective recognition of different target gases with a multilayer semiconducting metal oxide (SMOX)-based sensor device. Direct current (DC) electrical resistance measurements were performed during exposure to CO and ethanol as single gases and mixtures of highly porous metal oxide double- and single-layer sensors obtained by flame spray pyrolysis. The results show that the calculated resistance ratios of the single- and double-layer sensors are a good indicator for the presence of specific gases in the atmosphere, and can constitute some building blocks for the development of chemical logic devices. Due to the inherent lack of selectivity of SMOX-based gas sensors, such devices could be especially relevant for domestic applications.

Selectivity Enhancement by Using Double-Layer MOX-Based Gas Sensors Prepared by Flame Spray Pyrolysis (FSP)

PubMed Central

Rebholz, Julia; Grossmann, Katharina; Pham, David; Pokhrel, Suman; Mädler, Lutz; Weimar, Udo; Barsan, Nicolae

2016-01-01

Here we present a novel concept for the selective recognition of different target gases with a multilayer semiconducting metal oxide (SMOX)-based sensor device. Direct current (DC) electrical resistance measurements were performed during exposure to CO and ethanol as single gases and mixtures of highly porous metal oxide double- and single-layer sensors obtained by flame spray pyrolysis. The results show that the calculated resistance ratios of the single- and double-layer sensors are a good indicator for the presence of specific gases in the atmosphere, and can constitute some building blocks for the development of chemical logic devices. Due to the inherent lack of selectivity of SMOX-based gas sensors, such devices could be especially relevant for domestic applications. PMID:27608028

Enhancing the performance of blue GaN-based light emitting diodes with double electron blocking layers

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

Guo, Yao; Liang, Meng; Fu, Jiajia

2015-03-15

In this work, novel double Electron Blocking Layers for InGaN/GaN multiple quantum wells light-emitting diodes were proposed to mitigate the efficiency droop at high current density. The band diagram and carriers distributions were investigated numerically. The results indicate that due to a newly formed holes stack in the p-GaN near the active region, the hole injection has been improved and an uniform carriers distribution can be achieved. As a result, in our new structure with double Electron Blocking Layers, the efficiency droop has been reduced to 15.5 % in comparison with 57.3 % for the LED with AlGaN EBL atmore » the current density of 100 A/cm{sup 2}.« less

Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

NASA Astrophysics Data System (ADS)

Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

2016-07-01

Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

Asymmetry-symmetry transition of double-sided adhesive tapes

NASA Astrophysics Data System (ADS)

Yamaguchi, Tetsuo; Muroo, Hiroyuki; Sumino, Yutaka; Doi, Masao

2012-06-01

We report on the debonding process of a double-sided adhesive tape sandwiched between two glass plates. When the glass plates are separated from each other at a constant rate, a highly asymmetric extension of top and bottom adhesive layers and bending of the inner film are observed first. As the separation proceeds, the elongation of both layers becomes symmetric, and the inner film becomes flat again. When this happens, there appears a local maximum in the force-displacement curve. We explain this asymmetry-symmetry transition and discuss the role of the bimodal force-displacement relation of each adhesive layer. We also discuss the effect of the inner film thickness and the separation rate on the debonding behavior, which causes undesirable early detachment of the double-sided adhesive tape in a certain condition.

Synthesis of Novel Double-Layer Nanostructures of SiC–WOxby a Two Step Thermal Evaporation Process

PubMed Central

2009-01-01

A novel double-layer nanostructure of silicon carbide and tungsten oxide is synthesized by a two-step thermal evaporation process using NiO as the catalyst. First, SiC nanowires are grown on Si substrate and then high density W18O49nanorods are grown on these SiC nanowires to form a double-layer nanostructure. XRD and TEM analysis revealed that the synthesized nanostructures are well crystalline. The growth of W18O49nanorods on SiC nanowires is explained on the basis of vapor–solid (VS) mechanism. The reasonably better turn-on field (5.4 V/μm) measured from the field emission measurements suggest that the synthesized nanostructures could be used as potential field emitters. PMID:20596292

Enhanced stability of thin film transistors with double-stacked amorphous IWO/IWO:N channel layer

NASA Astrophysics Data System (ADS)

Lin, Dong; Pi, Shubin; Yang, Jianwen; Tiwari, Nidhi; Ren, Jinhua; Zhang, Qun; Liu, Po-Tsun; Shieh, Han-Ping

2018-06-01

In this work, bottom-gate top-contact thin film transistors with double-stacked amorphous IWO/IWO:N channel layer were fabricated. Herein, amorphous IWO and N-doped IWO were deposited as front and back channel layers, respectively, by radio-frequency magnetron sputtering. The electrical characteristics of the bi-layer-channel thin film transistors (TFTs) were examined and compared with those of single-layer-channel (i.e., amorphous IWO or IWO:N) TFTs. It was demonstrated to exhibit a high mobility of 27.2 cm2 V‑1 s‑1 and an on/off current ratio of 107. Compared to the single peers, bi-layer a-IWO/IWO:N TFTs showed smaller hysteresis and higher stability under negative bias stress and negative bias temperature stress. The enhanced performance could be attributed to its unique double-stacked channel configuration, which successfully combined the merits of the TFTs with IWO and IWO:N channels. The underlying IWO thin film provided percolation paths for electron transport, meanwhile, the top IWO:N layer reduced the bulk trap densities. In addition, the IWO channel/gate insulator interface had reduced defects, and IWO:N back channel surface was insensitive to the ambient atmosphere. Overall, the proposed bi-layer a-IWO/IWO:N TFTs show potential for practical applications due to its possibly long-term serviceability.

A Chemical-Adsorption Strategy to Enhance the Reaction Kinetics of Lithium-Rich Layered Cathodes via Double-Shell Surface Modification.

PubMed

Guo, Lichao; Li, Jiajun; Cao, Tingting; Wang, Huayu; Zhao, Naiqin; He, Fang; Shi, Chunsheng; He, Chunnian; Liu, Enzuo

2016-09-21

Sluggish surface reaction kinetics hinders the power density of Li-ion battery. Thus, various surface modification techniques have been applied to enhance the electronic/ionic transfer kinetics. However, it is challenging to obtain a continuous and uniform surface modification layer on the prime particles with structure integration at the interface. Instead of classic physical-adsorption/deposition techniques, we propose a novel chemical-adsorption strategy to synthesize double-shell modified lithium-rich layered cathodes with enhanced mass transfer kinetics. On the basis of experimental measurement and first-principles calculation, MoO2S2 ions are proved to joint the layered phase via chemical bonding. Specifically, the Mo-O or Mo-S bonds can flexibly rotate to bond with the cations in the layered phase, leading to the good compatibility between the thiomolybdate adsorption layer and layered cathode. Followed by annealing treatment, the lithium-excess-spinel inner shell forms under the thiomolybdate adsorption layer and functions as favorable pathways for lithium and electron. Meanwhile, the nanothick MoO3-x(SO4)x outer shell protects the transition metal from dissolution and restrains electrolyte decomposition. The double-shell modified sample delivers an enhanced discharge capacity almost twice as much as that of the unmodified one at 1 A g(-1) after 100 cycles, demonstrating the superiority of the surface modification based on chemical adsorption.

Excitation mechanism of surface plasmon polaritons in a double-layer wire grid structure

NASA Astrophysics Data System (ADS)

Motogaito, Atsushi; Nakajima, Tomoyasu; Miyake, Hideto; Hiramatsu, Kazumasa

2017-12-01

We characterize the optical properties of a double-layer wire grid structure and investigate in detail the excitation mechanism of surface plasmon polaritons (SPPs). Angular spectra for the transmittance of the transverse magnetic polarized light that are obtained through the experiment reveal two peaks. In addition, simulated mapping of the transmittance and the magnetic field distribution indicate that SPPs are excited in two areas of the wire grid structures: at the interface between the Au layer and the resist layer or the glass substrate and at the interface between the Au layer and air. The experimental data are consistent with the transmittance mapping result and the distribution of the magnetic field. Accordingly, we constructed a model of SPPs propagation. We consider that SPPs excited at the interface between the Au layer and the resist layer or the glass substrate strongly contribute to the extraordinary transmission observed in the wire grid structures.

LDHs/graphene film on aluminum alloys for active protection

NASA Astrophysics Data System (ADS)

Zhang, You; Yu, Peihang; Wang, Juping; Li, Yingdong; Chen, Fei; Wei, Kai; Zuo, You

2018-03-01

A layered double hydroxides (LDHs) nanocontainer film modified with graphene was fabricated on aluminum alloy via a facile two-step process. The structure, morphology and composition of LDHs/graphene film were investigated. Graphene layers were able to seal the pores of nest-like LDHs film. After the modification of graphene, the LDHs film presented hydrophobic (CA 127.8°) and enhanced anticorrosion properties. The active anticorrosion property of the composite film was attributed to the double functions of the impermeable and inert graphene layer and the active inhibitor-loaded LDHs underling film.

Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

NASA Astrophysics Data System (ADS)

Brown, Matthew A.; Abbas, Zareen; Kleibert, Armin; Green, Richard G.; Goel, Alok; May, Sylvio; Squires, Todd M.

2016-01-01

The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents the central element of electrochemical supercapacitors. The surface potential of such surfaces generally exceeds the electrokinetic potential, often substantially. Traditionally, a Stern layer of nonspecifically adsorbed ions has been invoked to rationalize the difference between these two potentials; however, the inability to directly measure the surface potential of dispersed systems has rendered quantitative measurements of the Stern layer potential, and other quantities associated with the outer Helmholtz plane, impossible. Here, we use x-ray photoelectron spectroscopy from a liquid microjet to measure the absolute surface potentials of silica nanoparticles dispersed in aqueous electrolytes. We quantitatively determine the impact of specific cations (Li+ , Na+ , K+ , and Cs+ ) in chloride electrolytes on the surface potential, the location of the shear plane, and the capacitance of the Stern layer. We find that the magnitude of the surface potential increases linearly with the hydrated-cation radius. Interpreting our data using the simplest assumptions and most straightforward understanding of Gouy-Chapman-Stern theory reveals a Stern layer whose thickness corresponds to a single layer of water molecules hydrating the silica surface, plus the radius of the hydrated cation. These results subject electrical double-layer theories to direct and falsifiable tests to reveal a physically intuitive and quantitatively verified picture of the Stern layer that is consistent across multiple electrolytes and solution conditions.

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

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

Ferencz, Zs.; Szabados, M.; Varga, G.

2016-01-15

A mechanochemical method (grinding the components without added water – dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution – wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure wasmore » also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic–inorganic nanocomposites: LDHs intercalated with amino acid anions. - Graphical abstract: Amino acid anion-Ca(II)Fe(III)-LDHs were successfully prepared by a two-step milling procedure. - Highlights: • Synthesis of pristine and amino acid intercalated CaFe-LDHs by two-step milling. • Identifying the optimum synthesis and intercalation parameters. • Characterisation of the samples with a range of instrumental methods.« less

A linear helicon plasma device with controllable magnetic field gradient.

PubMed

Barada, Kshitish K; Chattopadhyay, P K; Ghosh, J; Kumar, Sunil; Saxena, Y C

2012-06-01

Current free double layers (CFDLs) are localized potential structures having spatial dimensions - Debye lengths and potential drops of more than local electron temperature across them. CFDLs do not need a current for them to be sustained and hence they differ from the current driven double layers. Helicon antenna produced plasmas in an expanded chamber along with an expanding magnetic field have shown the existence of CFDL near the expansion region. A helicon plasma device has been designed, fabricated, and installed in the Institute for Plasma Research, India to study the role of maximum magnetic field gradient as well as its location with respect to the geometrical expansion region of the chamber in CFDL formation. The special feature of this machine consisting of two chambers of different radii is its capability of producing different magnetic field gradients near the physical boundary between the two chambers either by changing current in one particular coil in the direction opposite to that in other coils and/or by varying the position of this particular coil. Although, the machine is primarily designed for CFDL experiments, it is also capable of carrying out many basic plasma physics experiments such as wave propagation, wave coupling, and plasma instabilities in a varying magnetic field topology. In this paper, we will present the details of the machine construction, its specialties, and some preliminary results about the production and characterization of helicon plasma in this machine.

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

NASA Astrophysics Data System (ADS)

Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

Al(OH)3 and Ca(OH)2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. Ca-Al precursor (C3A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO4 LDH product. Ca-Al-CrO4 LDH phase occurred preferentially to Ca-Al-MCl2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist.

Dependence of the Carrier Transport Characteristics on the Buried Layer Thickness in Ambipolar Double-Layer Organic Field-Effect Transistors Investigated by Electrical and Optical Measurements

NASA Astrophysics Data System (ADS)

Zhang, Le; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2013-05-01

By using current-voltage (I-V) measurements and optical modulation spectroscopy, we investigated the dependence of the carrier behaviour on the film thickness of the buried pentacene layer in C60/pentacene ambipolar double-layer organic field-effect transistors (OFETs). It was found that the buried pentacene layer not only acted as a hole transport layer, but also accounted for the properties of the C60/pentacene interface. The hole and electron behaviour exhibited different thickness dependence on the buried pentacene layer, implying the presence of the spatially separated conduction paths. It was suggested that the injected holes transported along the pentacene/gate dielectric interface, which were little affected by the buried pentacene layer thickness or the upper C60 layer; while, the injected electrons accumulated at the C60/pentacene interface, which were sensitive to the interfacial conditions or the buried pentacene layer. Furthermore, it was suggested that the enhanced surface roughness of the buried pentacene layer was responsible for the observed electron behaviour, especially when dpent>10 nm.

Zn- and Co-based layered double hydroxides: prediction of the a parameter from the fraction of trivalent cations and vice versa

PubMed Central

Richardson, Ian G.

2013-01-01

A recently proposed method to calculate the a parameter of the unit cell of layered double hydroxides from the fraction of trivalent cations is extended to Zn- and Co-based phases. It is shown to be useful as a sanity test for extant and future structure determinations and computer-simulation studies. PMID:23873067

Performance of Electric Double-Layer Capacitor Simulators

NASA Astrophysics Data System (ADS)

Funabiki, Shigeyuki; Kodama, Shinsuke; Yamamoto, Masayoshi

This paper proposes a simulator of EDLC, which realizes the performance equivalent to electric double-layer capacitors (EDLCs). The proposed simulator consists of an electrolytic capacitor and a two-quadrant chopper working as a current source. Its operation principle is described in the first place. The voltage dependence of capacitance of EDLCs is taken into account. The performance of the proposed EDLC simulator is verified by computer simulations.

Sol-gel-derived hydroxyapatite-carbon nanotube/titania coatings on titanium substrates.

PubMed

Ji, Xiaoli; Lou, Weiwei; Wang, Qi; Ma, Jianfeng; Xu, Haihong; Bai, Qing; Liu, Chuantong; Liu, Jinsong

2012-01-01

In this paper, hydroxyapatite-carbon nanotube/titania (HA-CNT/TiO(2)) double layer coatings were successfully developed on titanium (Ti) substrates intended for biomedical applications. A TiO(2) coating was firstly developed by anodization to improve bonding between HA and Ti, and then the layer of HA and CNTs was coated on the surface by the sol-gel process to improve the biocompatibility and mechanical properties of Ti. The surfaces of double layer coatings were uniform and crack-free with a thickness of about 7 μm. The bonding strength of the HA-CNT/TiO(2) coating was higher than that of the pure HA and HA-CNT coatings. Additionally, in vitro cell experiments showed that CNTs promoted the adhesion of preosteoblasts on the HA-CNT/TiO(2) double layer coatings. These unique surfaces combined with the osteoconductive properties of HA exhibited the excellent mechanical properties of CNTs. Therefore, the developed HA-CNT/TiO(2) coatings on Ti substrates might be a promising material for bone replacement.

Super-hydrophilic copper sulfide films as light absorbers for efficient solar steam generation under one sun illumination

NASA Astrophysics Data System (ADS)

Guo, Zhenzhen; Ming, Xin; Wang, Gang; Hou, Baofei; Liu, Xinghang; Mei, Tao; Li, Jinhua; Wang, Jianying; Wang, Xianbao

2018-02-01

Solar steam technology is one of the simplest, most direct and effective ways to harness solar energy through water evaporation. Here, we report the development using super-hydrophilic copper sulfide (CuS) films with double-layer structures as light absorbers for solar steam generation. In the double-layer structure system, a porous mixed cellulose ester (MCE) membrane is used as a supporting layer, which enables water to get into the CuS light absorbers through a capillary action to provide continuous water during solar steam generation. The super-hydrophilic property of the double-layer system (CuS/MCE) leads to a thinner water film close to the air-water interface where the surface temperature is sufficiently high, leading to more efficient evaporation (˜80 ± 2.5%) under one sun illumination. Furthermore, the evaporation efficiencies still keep a steady value after 15 cycles of testing. The super-hydrophilic CuS film is promising for practical application in water purification and evaporation as a light absorption material.

KC-135 aero-optical turbulent boundary layer/shear layer experiment revisited

NASA Technical Reports Server (NTRS)

Craig, J.; Allen, C.

1987-01-01

The aero-optical effects associated with propagating a laser beam through both an aircraft turbulent boundary layer and artificially generated shear layers are examined. The data present comparisons from observed optical performance with those inferred from aerodynamic measurements of unsteady density and correlation lengths within the same random flow fields. Using optical instrumentation with tens of microsecond temporal resolution through a finite aperture, optical performance degradation was determined and contrasted with the infinite aperture time averaged aerodynamic measurement. In addition, the optical data were artificially clipped to compare to theoretical scaling calculations. Optical instrumentation consisted of a custom Q switched Nd:Yag double pulsed laser, and a holographic camera which recorded the random flow field in a double pass, double pulse mode. Aerodynamic parameters were measured using hot film anemometer probes and a five hole pressure probe. Each technique is described with its associated theoretical basis for comparison. The effects of finite aperture and spatial and temporal frequencies of the random flow are considered.

Control of Interfacial Phenomena in Artificial Oxide Heterostructures

DTIC Science & Technology

2015-09-01

heterostructures using the field effect to control superconductivity, magnetism, and metal‐insulator transitions. We also identify the existence of double TiO2 ...double TiO2 layers play a crucial role in determining the superconducting states of monolayer FeSe/SrTiO3. 15. SUBJECT TERMS Thin films, conductor...development of oxide‐based electronic devices.  We also identify the existence of double  TiO2   layers at the surface of SrTiO3 in the recently

Formation of lunar basin rings

USGS Publications Warehouse

Hodges, C.A.; Wilhelms, D.E.

1978-01-01

The origin of the multiple concentric rings that characterize lunar impact basins, and the probable depth and diameter of the transient crater have been widely debated. As an alternative to prevailing "megaterrace" hypotheses, we propose that the outer scarps or mountain rings that delineate the topographic rims of basins-the Cordilleran at Orientale, the Apennine at Imbrium, and the Altai at Nectaris-define the transient cavities, enlarged relatively little by slumping, and thus are analogous to the rim crests of craters like Copernicus; inner rings are uplifted rims of craters nested within the transient cavity. The magnitude of slumping that occurs on all scarps is insufficient to produce major inner rings from the outer. These conclusions are based largely on the observed gradational sequence in lunar central uplifts:. from simple peaks through somewhat annular clusters of peaks, peak and ring combinations and double ring basins, culminating in multiring structures that may also include peaks. In contrast, belts of slump terraces are not gradational with inner rings. Terrestrial analogs suggest two possible mechanisms for producing rings. In some cases, peaks may expand into rings as material is ejected from their cores, as apparently occurred at Gosses Bluff, Australia. A second process, differential excavation of lithologically diverse layers, has produced nested experimental craters and is, we suspect, instrumental in the formation of terrestrial ringed impact craters. Peak expansion could produce double-ring structures in homogeneous materials, but differential excavation is probably required to produce multiring and peak-in-ring configurations in large lunar impact structures. Our interpretation of the representative lunar multiring basin Orientale is consistent with formation of three rings in three layers detected seismically in part of the Moon-the Cordillera (basin-bounding) ring in the upper crust, the composite Montes Rook ring in the underlying, more coherent "heald" crust, and an innermost, 320-km ring at the crust-mantle interface. Depth-diameter ratios of 1 10to 1 15 are consistent with this interpretation and suggest that volumes of transient cavities and hence of basin ejecta may be considerably greater than commonly assumed. ?? 1978.