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.

Mg-Al and Zn-Fe layered double hydroxides used for organic species storage and controlled release.

PubMed

Seftel, E M; Cool, P; Lutic, D

2013-12-01

Layered double hydroxides (LDH) containing (Mg and Al) or (Zn and Fe) were prepared by coprecipitation at constant pH, using NaOH and urea as precipitation agents. The most pure LDH phase in the Zn/Fe system was obtained with urea and in Mg/Al system when using NaOH. The incorporation of phenyl-alanine (Phe) anions in the interlayer of the LDH was performed by direct coprecipitation, ionic exchange and structure reconstruction of the mixed oxide obtained by the calcination of the coprecipitated product at 400°C. The reconstruction method and the direct coprecipitation in a medium containing Phe in the initial mixture were less successful in terms of high yields of organic-mineral composite than the ionic exchange method. A spectacular change in sample morphology and yield in exchanged solid was noticed for the Zn3Fe sample obtained by ionic exchange for 6h with Phe solution. A delivery test in PBS of pH=7.4 showed the release of the Phe in several steps up to 25 h indicating different host-guest interactions between the Phe and the LDH matrix. This behavior makes the preparation useful to obtain late delivery drugs, by the incorporation of the anion inside the LDH layer. © 2013.

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.

Preparation of 5-benzotriazolyl-4-hydroxy-3- sec-butylbenzenesulfonate anion-intercalated layered double hydroxide and its photostabilizing effect on polypropylene

NASA Astrophysics Data System (ADS)

Li, Dianqing; Tuo, Zhenjun; Evans, David G.; Duan, Xue

2006-10-01

An organic UV absorber has been intercalated into a layered double hydroxide (LDH) host by ion-exchange method using ZnAl-NO 3-LDH as a precursor with an aqueous solution of the sodium salt of 5-benzotriazolyl-4-hydroxy-3- sec-butylbenzenesulfonic acid (BZO). After intercalation of the UV absorber, the interlayer distance in the LDHs increases from 0.89 to 2.32 nm. Infrared spectra and thermogravimetry and differential thermal analysis (TG-DTA) curves reveal the presence of a complex system of supramolecular host-guest interactions. The thermostability of BZO is markedly enhanced by intercalation in the LDH host. ZnAl-BZO-LDHs/polypropylene composite materials exhibit excellent UV photostability.

[Effects of precipitation intensity on soil organic carbon fractions and their distribution under subtropical forests of South China].

PubMed

Chen, Xiao-mei; Liu, Ju-xiu; Deng, Qi; Chu, Guo-wei; Zhou, Guo-yi; Zhang, De-qiang

2010-05-01

From December 2006 to June 2008, a field experiment was conducted to study the effects of natural precipitation, doubled precipitation, and no precipitation on the soil organic carbon fractions and their distribution under a successional series of monsoon evergreen broad-leaf forest, pine and broad-leaf mixed forest, and pine forest in Dinghushan Mountain of Southern China. Different precipitation treatments had no significant effects on the total organic carbon (TOC) concentration in the same soil layer under the same forest type (P > 0.05). In treatment no precipitation, particulate organic carbon (POC) and light fraction organic carbon (LFOC) were mainly accumulated in surface soil layer (0-10 cm); but in treatments natural precipitation and doubled precipitation, the two fractions were infiltrated to deeper soil layers. Under pine forest, soil readily oxidizable organic carbon (ROC) was significantly higher in treatment no precipitation than in treatments natural precipitation and doubled precipitation (P < 0.05). The percentage of soil POC, ROC, and LFOC to soil TOC was much greater under the forests at early successional stage than at climax stage, suggesting that the forest at early successional stage might not be an ideal place for soil organic carbon storage. Precipitation intensity less affected TOC, but had greater effects on the labile components POC, ROC, and LFOC.

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

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.

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.

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.

Highly efficient solution-processed phosphorescent organic light-emitting devices with double-stacked hole injection layers

NASA Astrophysics Data System (ADS)

Chen, Yuehua; Hao, Lin; Zhang, Xinwen; Zhang, Xiaolin; Liu, Mengjiao; Zhang, Mengke; Wang, Jiong; Lai, Wen-Yong; Huang, Wei

2017-08-01

In this paper, solution-processed nickel oxide (NiOx) is used as hole-injection layers (HILs) in solution-processed phosphorescent organic light-emitting diodes (PhOLEDs). Serious exciton quenching is verified at the NiOx/emitting layer (EML) interface, resulting in worse device performance. The device performance is significantly improved by inserting a layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) between the EML and NiOx. The solution-processed blue PhOLED with the double-stacked NiOx/PEDOT:PSS HILs shows a maximum current efficiency of 30.5 cd/A, which is 75% and 30% higher than those of the devices with a single NiOx HIL and a PEDOT:PSS HIL, respectively. Improvement of device efficiency can be attributed to reducing exciton quenching of the PEDOT:PSS layer as well as the electron blocking effect of the NiOx layer.

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.

Influence of tillage practices and straw incorporation on soil aggregates, organic carbon, and crop yields in a rice-wheat rotation system

PubMed Central

Song, Ke; Yang, Jianjun; Xue, Yong; Lv, Weiguang; Zheng, Xianqing; Pan, Jianjun

2016-01-01

In this study, a fixed-site field experiment was conducted to study the influence of different combinations of tillage and straw incorporation management on carbon storage in different-sized soil aggregates and on crop yield after three years of rice-wheat rotation. Compared to conventional tillage, the percentages of >2 mm macroaggregates and water-stable macroaggregates in rice-wheat double-conservation tillage (zero-tillage and straw incorporation) were increased 17.22% and 36.38% in the 0–15 cm soil layer and 28.93% and 66.34% in the 15–30 cm soil layer, respectively. Zero tillage and straw incorporation also increased the mean weight diameter and stability of the soil aggregates. In surface soil (0–15 cm), the maximum proportion of total aggregated carbon was retained with 0.25–0.106 mm aggregates, and rice-wheat double-conservation tillage had the greatest ability to hold the organic carbon (33.64 g kg−1). However, different forms occurred at higher levels in the 15–30 cm soil layer under the conventional tillage. In terms of crop yield, the rice grown under conventional tillage and the wheat under zero tillage showed improved equivalent rice yields of 8.77% and 6.17% compared to rice-wheat double-cropping under zero tillage or conventional tillage, respectively. PMID:27812038

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.

A hydrogel capsule as gate dielectric in flexible organic field-effect transistors

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

Dumitru, L. M.; Manoli, K.; Magliulo, M.

2015-01-01

A jellified alginate based capsule serves as biocompatible and biodegradable electrolyte system to gate an organic field-effect transistor fabricated on a flexible substrate. Such a system allows operating thiophene based polymer transistors below 0.5 V through an electrical double layer formed across an ion-permeable polymeric electrolyte. Moreover, biological macro-molecules such as glucose-oxidase and streptavidin can enter into the gating capsules that serve also as delivery system. An enzymatic bio-reaction is shown to take place in the capsule and preliminary results on the measurement of the electronic responses promise for low-cost, low-power, flexible electronic bio-sensing applications using capsule-gated organic field-effect transistors.

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.

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.

Use of an acidophilic yeast strain to enable the growth of leaching bacteria on solid media.

PubMed

Ngom, Baba; Liang, Yili; Liu, Yi; Yin, Huaqun; Liu, Xueduan

2015-03-01

In this study, a Candida digboiensis strain was isolated from a heap leaching plant in Zambia and used in double-layer agar plate to efficiently isolate and purify leaching bacteria. Unlike Acidiphilium sp., the yeast strain was tetrathionate tolerant and could metabolize a great range of organic compounds including organic acids. These properties allowed the yeast strain to enable and fasten the growth of iron and sulfur oxidizers on double-layer agar plate. The isolates were identified as Acidithiobacillus ferrooxidans FOX1, Leptospirillun ferriphilum BN, and Acidithiobacillus thiooxidans ZMB. These three leaching bacteria were inhibited by organic acids such as acetic and propionic acids; however, their activities were enhanced by Candida digboiensis NB under dissolved organic matter stress.

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.

Property Changes of Cyanate Ester/epoxy Insulation Systems Caused by AN Iter-Like Double Impregnation and by Reactor Irradiation

NASA Astrophysics Data System (ADS)

Prokopec, R.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

2010-04-01

Because of the double pancake design of the ITER TF coils the insulation will be applied in several steps. As a consequence, the conductor insulation as well as the pancake insulation will undergo multiple heat cycles in addition to the initial curing cycle. In particular the properties of the organic resin may be influenced, since its heat resistance is limited. Two identical types of sample consisting of wrapped R-glass/Kapton layers and vacuum impregnated with a cyanate ester/epoxy blend were prepared. The build-up of the reinforcement was identical for both insulation systems; however, one system was fabricated in two steps. In the first step only one half of the reinforcing layers was impregnated and cured. Afterwards the remaining layers were wrapped onto the already cured system, before the resulting system was impregnated and cured again. The mechanical properties were characterized prior to and after irradiation to fast neutron fluences of 1 and 2×1022 m-2 (E>0.1 MeV) in tension and interlaminar shear at 77 K. In order to simulate the pulsed operation of ITER, tension-tension fatigue measurements were performed in the load controlled mode. The results do not show any evidence for reduced mechanical strength caused by the additional heat cycle.

A novel coating concept for ileo-colonic drug targeting: proof of concept in humans using scintigraphy.

PubMed

Varum, F J O; Hatton, G B; Freire, A C; Basit, A W

2013-08-01

The in vivo proof of concept of a novel double-coating system, based on enteric polymers, which accelerated drug release in the ileo-colonic region, was investigated in humans. Prednisolone tablets were coated with a double-coating formulation by applying an inner layer composed of EUDRAGIT S neutralised to pH 8.0 and a buffer salt (10% KH₂PO₄), which was overcoated with layer of standard EUDRAGIT S organic solution. For comparison, a single coating system was produced by applying the same amount of EUDRAGIT S organic solution on the tablet cores. Dissolution tests on the tablets were carried out using USP II apparatus in 0.1N HCl for 2 h and subsequently in pH 7.4 Krebs bicarbonate buffer. For comparison, tablets were also tested under the USP method established for modified release mesalamine formulations. Ten fasted volunteers received the double-coated and single-coated tablets in a two-way crossover study. The formulations were radiolabelled and followed by gamma scintigraphy; the disintegration times and positions were recorded. There was no drug release from the single-coated or double-coated tablets in 0.1N HCl for 2h. The single-coated tablets showed slow release in subsequent Krebs bicarbonate buffer with a lag time of 120 min, while in contrast drug release from the double-coated tablets was initiated at 60 min. In contrast, using the USP dissolution method, normally employed for modified release mesalamine products, no discrimination was attained. The in vivo disintegration of the single-coated EUDRAGIT S tablets in the large intestine was erratic. Furthermore, in 2 volunteers, the single-coated tablet was voided intact. Double-coated tablets disintegrated in a more consistent way, mainly in the ileo-caecal junction or terminal ileum. The accelerated in vivo disintegration of the double-coating EUDRAGIT S system can overcome the limitations of conventional enteric coatings targeting the colon and avoid the pass-through of intact tablets. Moreover, Krebs bicarbonate buffer has the ability to discriminate between formulations designed to target the ileo-colonic region. Copyright © 2013 Elsevier B.V. All rights reserved.

Influence of confinement layers in the emitting layer of the blue phosphorescent organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Ji, Chang-Yan; Gu, Zheng-Tian; Kou, Zhi-Qi

2016-10-01

The electrical and optical properties of the blue phosphorescent organic light-emitting diodes (PHOLEDs) can be affected by the various structure of confinement layer in the emitting layer (EML). A series of devices with different electron or hole confinement layer (TCTA or Bphen) are fabricated, it is more effective to balance charge carriers injection for the device with the double electron confinement layers structure, the power efficiency and luminance can reach 17.7 lm/W (at 103 cd/m2) and 3536 cd/m2 (at 8 V). In case of the same double electron confinement layers, another series of devices with different profile of EML are fabricated by changing the confinement layers position, the power efficiency and luminance can be improved to 21.7 lm/W (at 103 cd/m2) and 7674 cd/m2 (at 8 V) when the thickness of EML separated by confinement layers increases gradually from the hole injection side to the electron injection side, the driving voltage can also be reduced.

In Situ Transformation of MOFs into Layered Double Hydroxide Embedded Metal Sulfides for Improved Electrocatalytic and Supercapacitive Performance.

PubMed

Yilmaz, Gamze; Yam, Kah Meng; Zhang, Chun; Fan, Hong Jin; Ho, Ghim Wei

2017-07-01

Direct adoption of metal-organic frameworks (MOFs) as electrode materials shows impoverished electrochemical performance owing to low electrical conductivity and poor chemical stability. In this study, we demonstrate self-templated pseudomorphic transformation of MOF into surface chemistry rich hollow framework that delivers highly reactive, durable, and universal electrochemically active energy conversion and storage functionalities. In situ pseudomorphic transformation of MOF-derived hollow rhombic dodecahedron template and sulfurization of nickel cobalt layered double hydroxides (NiCo-LDHs) lead to the construction of interlayered metal sulfides (NiCo-LDH/Co 9 S 8 ) system. The embedment of metal sulfide species (Co 9 S 8 ) at the LDH intergalleries offers optimal interfacing of the hybrid constituent elements and materials stability. The hybrid NiCo-LDH/Co 9 S 8 system collectively presents an ideal porous structure, rich redox chemistry, and high electrical conductivity matrix. This leads to a significant enhancement in its complementary electrocatalytic hydrogen evolution and supercapacitive energy storage properties. This work establishes the potential of MOF derived scaffold for designing of novel class hybrid inorganic-organic functional materials for electrochemical applications and beyond. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Charge transport in quantum dot organic solar cells with Si quantum dots sandwiched between poly(3-hexylthiophene) (P3HT) absorber and bathocuproine (BCP) transport layers

NASA Astrophysics Data System (ADS)

Verma, Upendra Kumar; Kumar, Brijesh

2017-10-01

We have modeled a multilayer quantum dot organic solar cell that explores the current-voltage characteristic of the solar cell whose characteristics can be tuned by varying the fabrication parameters of the quantum dots (QDs). The modeled device consists of a hole transport layer (HTL) which doubles up as photon absorbing layer, several quantum dot layers, and an electron transport layer (ETL). The conduction of charge carriers in HTL and ETL has been modeled by the drift-diffusion transport mechanism. The conduction and recombination in the quantum dot layers are described by a system of coupled rate equations incorporating tunneling and bimolecular recombination. Analysis of QD-solar cells shows improved device performance compared to the similar bilayer and trilayer device structures without QDs. Keeping other design parameters constant, solar cell characteristics can be controlled by the quantum dot layers. Bimolecular recombination coefficient of quantum dots is a prime factor which controls the open circuit voltage (VOC) without any significant reduction in short circuit current (JSC).

Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Tsukanov, A. A.; Psakhie, S. G.

2016-01-01

The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered.

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).

Universal chemiluminescence flow-through device based on directed self-assembly of solid-state organic chromophores on layered double hydroxide matrix.

PubMed

Wang, Zhihua; Teng, Xu; Lu, Chao

2013-02-19

In this work, a universal chemiluminescence (CL) flow-through device suitable for various CL resonance energy transfer (CRET) systems has been successfully fabricated. Highly efficient CRET in solid-state photoactive organic molecules can be achieved by assembling them on the surface of layered double hydroxides (LDHs). We attribute these observations to the suppression of the intermolecular π-π stacking interactions among aromatic rings and the improvement of molecular orientation and planarity in the LDH matrix, enabling a remarkable increase in fluorescence lifetime and quantum yield of organic molecules. Under optimal conditions, using peroxynitrous acid-fluorescein dianion (FLUD) as a model CRET system, trace FLUD (10 μM) was assembled on the surface of LDHs. Peroxynitrous acid/nitrite could be assayed in the range of 1.0-500 μM, and the detection limit for peroxynitrous acid/nitrite (S/N = 3) was 0.6 μM. This CL flow-through device exhibited operational stability, high reproducibility, and long lifetime. While LDHs were immobilized in a flow-through device in the absence of FLUD, the detection limit for peroxynitrous acid/nitrite was 100 μM. On the other hand, FLUD at the same concentration can not enhance the CL intensity of peroxynitrous acid system. This fabricated CL flow-through column has been successfully applied to determine nitrite in sausage samples with recoveries of 98-102%. These satisfactory results demonstrated that our studies pave a novel way toward flow-through column-based CRET using solid-state organic molecules as acceptors for signal amplification.

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.

Organic-inorganic hybrid nanocomposites based on chitosan derivatives and layered double hydroxides with intercalated phacolysin as ocular delivery system

NASA Astrophysics Data System (ADS)

Qin, Zhiguo; Zhang, Jie; Chi, Huibo; Cao, Feng

2015-12-01

This study was mainly aimed to evaluate the potential use of a novel ocular drug delivery system, organic-inorganic hybrid nanocomposites based on chitosan derivatives and layered double hydroxides (LDH). Organic polymers of chitosan-glutathione (CG) and pre-activated chitosan-glutathione (CG-2MNA) were successfully synthesized and characterized. LDH with intercalated phacolysin (PCL), including larger hexagonal LDH-PCL (Lh-LDH-PCL), larger spherical LDH-PCL (Ls-LDH-PCL), smaller hexagonal LDH-PCL (Sh-LDH-PCL), CG hybrid LDH-PCL (LDH-PCL-CG), and CG-2MNA hybrid LDH-PCL (LDH-PCL-CG-2MNA), were prepared. The nanocomposites with particle size of 107.2-274.9 nm were characterized by powder X-ray diffraction, Fourier transform infrared, transmission electron micrographs, etc. In vivo precorneal retention studies showed that the detectable time of all nanocomposites was prolonged from 2 to 6 h in comparison to PCL saline. Accordingly, the AUC0-6h values of Lh-LDH-PCL, Ls-LDH-PCL, Sh-LDH-PCL, LDH-PCL-CG, and LDH-PCL-CG-2MNA nanocomposites were increased by 2.27-, 2.08-, 3.08-, 4.67-, and 3.36-fold, respectively. The Draize test and hematoxylin and eosin staining demonstrated that modified LDH had no eye irritation after single and repeated administration. These results indicated that chitosan derivatives-LDH hybrid nanocomposite dispersion could be a promising ocular drug delivery system to improve precorneal retention time of drugs.

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.

Enhanced photocatalytic properties of the 3D flower-like Mg-Al layered double hydroxides decorated with Ag{sub 2}CO{sub 3} under visible light illumination

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

Ao, Yanhui, E-mail: andyao@hhu.edu.cn; Wang, Dandan; Wang, Peifang

Highlights: • 3D flower-like Ag{sub 2}CO{sub 3}/Mg-Al layered double hydroxide composite was prepared. • The nanocomposites exhibited high photocatalytic activities on different organic pollutants. • The mechanism of the enhanced activity were investigated. - Abstract: A facile anion-exchange precipitation method was employed to synthesize 3D flower-like Ag{sub 2}CO{sub 3}/Mg-Al layered double hydroxide composite photocatalyst. Results showed that Ag{sub 2}CO{sub 3} nanoparticles dispersed uniformly on the petals of the flower-like Mg-Al LDH. The obtained nanocomposites exhibited high photocatalytic activities on different organic pollutants (cationic and anionic dyes, phenol) under visible light illumination. The high photocatalytic activity can be ascribed to themore » special structure which accomplishes the wide-distribution of Ag{sub 2}CO{sub 3} nanoparticles on the surfaces of the 3D flower-like nanocomposites. Therefore, it can provide much more active sites for the degradation of organic pollutant. Then the photocatalytic mechanism was also verified by reactive species trapping experiments in detail. The work would pave a facile way to prepare LDHs based hierarchical photocatalysts with high activity for the degradation of wide range organic pollutants under visible light irradiation.« less

Ionic Liquids as Surfactants for Layered Double Hydroxide Fillers: Effect on the Final Properties of Poly(Butylene Adipate-Co-Terephthalate)

PubMed Central

Livi, Sébastien; Lins, Luanda Chaves; Peter, Jakub; Kredatusova, Jana; Pruvost, Sébastien

2017-01-01

In this work, phosphonium ionic liquids (ILs) based on tetra-alkylphosphonium cations combined with carboxylate, phosphate and phosphinate anions, were used for organic modification of layered double hydroxide (LDH). Two different amounts (2 and 5 wt %) of the organically modified LDHs were mixed with poly(butylene adipate-co-terephthalate) (PBAT) matrix by melt extrusion. All prepared PBAT/IL-modified-LDH composites exhibited increased mechanical properties (20–50% Young’s modulus increase), decreased water vapor permeability (30–50% permeability coefficient reduction), and slight decreased crystallinity (10–30%) compared to the neat PBAT. PMID:28956811

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

Hierarchical Nanostructures of Metal-Organic Frameworks Applied in Gas Separating ZIF-8-on-ZIF-67 Membranes.

PubMed

Knebel, Alexander; Wulfert-Holzmann, Paul; Friebe, Sebastian; Pavel, Janet; Strauß, Ina; Mundstock, Alexander; Steinbach, Frank; Caro, Jürgen

2018-04-17

Membranes from metal-organic frameworks (MOFs) are highly interesting for industrial gas separation applications. Strongly improved performances for carbon capture and H 2 purification tasks in MOF membranes are obtained by using highly reproducable and very accuratly, hierarchically grown ZIF-8-on-ZIF-67 (ZIF-8@ZIF-67) nanostructures. To forgo hardly controllable solvothermal synthesis, particles and layers are prepared by self-assembling methods. It was possible for the first time to confirm ZIF-8-on-ZIF-67 membrane growth on rough and porous ceramic supports using the layer-by-layer deposition. Additionally, hierarchical particles are made in a fast RT synthesis with high monodispersity. Characterization of the hierarchical and epitaxial grown layers and particles is performed by SEM, TEM, EDXM and gas permeation. The system ZIF-8@ZIF-67 shows a nearly doubled H 2 /CO 2 separation factor, regardless of whether neat membrane or mixed-matrix-membrane in comparison to other MOF materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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.

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.

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.

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.

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.

High-temperature chemical and microstructural transformations of an organic-inorganic nanohybrid captopril intercalated Mg-Al layered double hydroxide

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

Zhang Hui; Guo Shaohuan; Zou Kang

The thermal evolution of a crystalline organic-inorganic nanohybrid captopril intercalated Mg-Al layered double hydroxide (LDH) [Mg{sub 0.68}Al{sub 0.32}(OH){sub 2}] (C{sub 9}H{sub 13}NO{sub 3}S){sub 0.130}(CO{sub 3}){sub 0.030}.0.53H{sub 2}O obtained by coprecipitation method is studied based upon in situ high-temperature X-ray diffraction, in situ infrared and thermogravimetric analysis coupled with mass spectroscopy analysis. The results reveal that a metastable quasi-interstratified layered nanohybrid involving carbonate-LDH and reoriented less ordered captopril-LDH was firstly observed as captopril-LDH heat-treated between 140 and 230 deg. C. The major decomposition/combustion of interlayer organics occur between 270 and 550 deg. C. A schematic model on chemical and microstructural evolutionmore » of this particular drug-inorganic nanohybrid upon heating in air atmosphere is proposed.« less

Dynamics of multiple double layers in high pressure glow discharge in a simple torus

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

Kumar Paul, Manash, E-mail: manashkr@gmail.com; Sharma, P. K.; Thakur, A.

2014-06-15

Parametric characterization of multiple double layers is done during high pressure glow discharge in a toroidal vessel of small aspect ratio. Although glow discharge (without magnetic field) is known to be independent of device geometry, but the toroidal boundary conditions are conducive to plasma growth and eventually the plasma occupy the toroidal volume partially. At higher anode potential, the visibly glowing spots on the body of spatially extended anode transform into multiple intensely luminous spherical plasma blob structures attached to the tip of the positive electrode. Dynamics of multiple double layers are observed in argon glow discharge plasma in presencemore » of toroidal magnetic field. The radial profiles of plasma parameters measured at various toroidal locations show signatures of double layer formation in our system. Parametric dependence of double layer dynamics in presence of toroidal magnetic field is presented here.« 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.

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.

Effect of alkyl branches on the thermal stability of quaternary ammonium cations in organic electrolytes for electrochemical double layer capacitors.

PubMed

Ahn, Yong Nam; Lee, Sung Hoon; Lee, Goo Soo; Kim, Hyunbin

2017-08-02

Quaternary ammoniums are cations having widespread use in organic electrolytes for high performance electrochemical double layer capacitors (EDLCs) due to their various advantages such as high electrochemical stability and inexpensive production cost. However, the decomposition of quaternary ammoniums via Hofmann elimination hinders their applications for EDLCs operating at elevated temperatures. This study systematically investigates the reactivity of four different quaternary ammoniums (tetraethyl-, triethylmethyl-, diethyldimethyl-, and trimethylethyl-ammonium) in EDLC by utilizing density functional theory calculations and Brownian dynamics simulations complemented with molecular dynamics simulations. It is found that ammonium stability reduces upon increasing the number of ethyl branches that have a stronger positive charge than the methyl groups. However, the contribution of the entropy change to the reaction free energy makes trimethylethylammonium less stable than diethyldimethylammonium at room temperature although the former has less ethyl branches than the latter. Trimethylethylammonium becomes the most stable at a high temperature of 488 K above which the activation free energy becomes effectively negligible and thus the number of reactive sites determines the overall stability. The fundamental understanding of the ammonium decompositions through Hofmann elimination demonstrated in this study is expected to contribute to developing new long-life organic electrolyte systems for high-temperature applications.

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.

Carbazole/triarylamine based polymers as a hole injection/transport layer in organic light emitting devices.

PubMed

Wang, Hui; Ryu, Jeong-Tak; Kwon, Younghwan

2012-05-01

This study examined the influence of the charge injection barriers on the performance of organic light emitting diodes (OLEDs) using polymers with a stepwise tuned ionization potential (I(p) approximately -5.01 - -5.29 eV) between the indium tin oxide (ITO) (phi approximately -4.8 eV) anode and tris(8-hydroxyquinolinato) aluminium (Alq3) (I(p) approximately -5.7 eV) layer. The energy levels of the polymers were tuned by structural modification. Double layer devices were fabricated with a configuration of ITO/polymer/Alq3/LiF/Al, where the polymers, Alq3, and LiF/Al were used as the hole injection/transport layer, emissive electron transport layer, and electron injection/cathode, respectively. Using the current density-voltage (J-V), luminescence-voltage (L-V) and efficiencies in these double layer devices, the device performance was evaluated in terms of the energy level alignments at the interfaces, such as the hole injection barriers (phi(h)(iTO/polymer) and phi(h)(polymer/Alq3)) from ITO through the polymers into the Alq3 layer, and the electron injection barrier (phi(e)(polymer/Alq3) or electron/exciton blocking barrier) at the polymer/Alq3 interface.

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.

[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.

Interactive High-Relief Reconstruction for Organic and Double-Sided Objects from a Photo.

PubMed

Yeh, Chih-Kuo; Huang, Shi-Yang; Jayaraman, Pradeep Kumar; Fu, Chi-Wing; Lee, Tong-Yee

2017-07-01

We introduce an interactive user-driven method to reconstruct high-relief 3D geometry from a single photo. Particularly, we consider two novel but challenging reconstruction issues: i) common non-rigid objects whose shapes are organic rather than polyhedral/symmetric, and ii) double-sided structures, where front and back sides of some curvy object parts are revealed simultaneously on image. To address these issues, we develop a three-stage computational pipeline. First, we construct a 2.5D model from the input image by user-driven segmentation, automatic layering, and region completion, handling three common types of occlusion. Second, users can interactively mark-up slope and curvature cues on the image to guide our constrained optimization model to inflate and lift up the image layers. We provide real-time preview of the inflated geometry to allow interactive editing. Third, we stitch and optimize the inflated layers to produce a high-relief 3D model. Compared to previous work, we can generate high-relief geometry with large viewing angles, handle complex organic objects with multiple occluded regions and varying shape profiles, and reconstruct objects with double-sided structures. Lastly, we demonstrate the applicability of our method on a wide variety of input images with human, animals, flowers, etc.

Efficient double-emitting layer inverted organic light-emitting devices with different spacer layers

NASA Astrophysics Data System (ADS)

Nie, Qu-yang; Zhang, Fang-hui

2017-09-01

Double-emitting layer inverted organic light-emitting devices (IOLEDs) with different spacer layers were investigated, where 2,20,7,70-tetrakis(carbazol-9-yl)-9,9-spirobifluorene (CBP), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen) and 4,40,400-tris(N-carbazolyl)-triphenylamine (TCTA) were used as spacer layers, respectively, and GIr1 and R-4b were used as green and red guest phosphorescent materials, respectively. The results show that the device with BCP spacer layer has the best performance. The maximum current efficiency of the BCP spacer layer device reaches up to 24.15 cd·A-1 when the current density is 3.99 mA·cm-2, which is 1.23 times bigger than that of the CBP spacer layer device. The performance is better than that of corresponding conventional device observably. The color coordinate of the device with BCP spacer layer only changes from (0.625 1, 0.368 0) to (0.599 5, 0.392 8) when the driving voltage increases from 6 V to 10 V, so it shows good stability in color coordinate, which is due to the adoption of the co-doping evaporation method for cladding luminous layer and the effective restriction of spacer layer to carriers in emitting layer.

Multi-layer topological transmissions of spoof surface plasmon polaritons.

PubMed

Pan, Bai Cao; Zhao, Jie; Liao, Zhen; Zhang, Hao Chi; Cui, Tie Jun

2016-03-04

Spoof surface plasmon polaritons (SPPs) in microwave frequency provide a high field confinement in subwavelength scale and low-loss and flexible transmissions, which have been widely used in novel transmission waveguides and functional devices. To play more important roles in modern integrated circuits and systems, it is necessary and helpful for the SPP modes to propagate among different layers of devices and chips. Owing to the highly confined property and organized near-field distribution, we show that the spoof SPPs could be easily transmitted from one layer into another layer via metallic holes and arc-shaped transitions. Such designs are suitable for both the ultrathin and flexible single-strip SPP waveguide and double-strip SPP waveguide for active SPP devices. Numerical simulations and experimental results demonstrate the broadband and high-efficiency multi-layer topological transmissions with controllable absorption that is related to the superposition area of corrugated metallic strips. The transmission coefficient of single-strip SPP waveguide is no worse than -0.8 dB within frequency band from 2.67 GHz to 10.2 GHz while the transmission of double-strip SPP waveguide keeps above -1 dB within frequency band from 2.26 GHz to 11.8 GHz. The proposed method will enhance the realizations of highly complicated plasmonic integrated circuits.

Double Layers in Astrophysics

NASA Technical Reports Server (NTRS)

Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

1987-01-01

Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

Photoprecursor approach as an effective means for preparing multilayer organic semiconducting thin films by solution processes

PubMed Central

Yamaguchi, Yuji; Suzuki, Mitsuharu; Motoyama, Takao; Sugii, Shuhei; Katagiri, Chiho; Takahira, Katsuya; Ikeda, Shinya; Yamada, Hiroko; Nakayama, Ken-ichi

2014-01-01

The vertical composition profile of active layer has a major effect on the performance of organic photovoltaic devices (OPVs). While stepwise deposition of different materials is a conceptually straightforward method for controlled preparation of multi-component active layers, it is practically challenging for solution processes because of dissolution of the lower layer. Herein, we overcome this difficulty by employing the photoprecursor approach, in which a soluble photoprecursor is solution-deposited then photoconverted in situ to a poorly soluble organic semiconductor. This approach enables solution-processing of the p-i-n triple-layer architecture that has been suggested to be effective in obtaining efficient OPVs. We show that, when 2,6-dithienylanthracene and a fullerene derivative PC71BM are used as donor and acceptor, respectively, the best p-i-n OPV affords a higher photovoltaic efficiency than the corresponding p-n device by 24% and bulk-heterojunction device by 67%. The photoprecursor approach is also applied to preparation of three-component p-i-n films containing another donor 2,6-bis(5′-(2-ethylhexyl)-(2,2′-bithiophen)-5-yl)anthracene in the i-layer to provide a nearly doubled efficiency as compared to the original two-component p-i-n system. These results indicate that the present approach can serve as an effective means for controlled preparation of well-performing multi-component active layers in OPVs and related organic electronic devices. PMID:25413952

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.

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.

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.

Pulsed laser deposition of functionalized Mg-Al layered double hydroxide thin films

NASA Astrophysics Data System (ADS)

Vlad, A.; Birjega, R.; Tirca, I.; Matei, A.; Mardare, C. C.; Hassel, A. W.; Nedelcea, A.; Dinescu, M.; Zavoianu, R.

2018-02-01

In this paper, magnesium-aluminium layered double hydroxide (LDH) has been functionalized with sodium dodecyl sulfate (DS) and deposited as thin film by pulsed laser deposition (PLD). Mg, Al-LDH powders were prepared by co-precipitation and used as reference material. Intercalation of DS as an anionic surfactant into the LDHs host layers has been prepared in two ways: co-precipitation (P) and reconstruction (R). DS intercalation occurred in LDH powder via both preparation methods. The films deposited via PLD, in particular at 532 and 1064 nm, preserve the organic intercalated layered structure of the targets prepared from these powders. The results reveal the ability of proposed deposition technique to produce functional composite organo-modified LDHs thin films.

Solvent-free synthesis of new metal phosphites with double-layered, pillared-layered, and framework structures

NASA Astrophysics Data System (ADS)

Liu, Lin; Zhang, Wei; Shi, Zhonghua; Chen, Yaoqiang; Lin, Zhien

2014-12-01

Three new metal phosphites, formulated as (H3O)2·Mn2(HPO3)3 (1), Co(bpy) (H2O) (HPO3) (2), and H2tmpda·Zn3(HPO3)4 (3), have been synthesized under solvent-free conditions, where bpy = 4,4‧-bipyridine, and tmpda = N,N,N‧,N‧-tetramethyl-1,3-propanediamine. Compound 1 has a double-layered structure with a thickness of 5.68 Å. Compound 2 has an inorganic-organic hybrid framework with cobalt phosphite layers pillared by bpy ligands. Compound 3 has a three-dimensional open-framework structure containing 8-ring channels. The temperature dependence of the magnetic susceptibility of compounds 1 and 2 were also investigated.

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.

Selectively catalytic activity of metal–organic frameworks depending on the N-position within the pyridine ring of their building blocks

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

Xu, Haitao, E-mail: xuhaitao@ecust.edu.cn; Gou, Yongxia; Ye, Jing

2016-05-15

Iron metal–organic frameworks (MOFs) [Fe(L){sub 2}(SCN){sub 2}]{sub ∝} (L1: 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene for 1Fe; and L2: 3-bpdh=2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene for 2Fe) were assembled in a MeOH–H{sub 2}O solvent system. 1Fe exhibits a two-dimensional extended-grid network, whereas 2Fe exhibits a stair-like double-chain; the N-position within the pyridine ring of the complexes was observed to regulate the MOF structure as layers or chains. Furthermore, selectively catalytic activity was observed for the layered MOF but not the chain-structured MOF; micro/nanoparticles of the layered MOF were therefore investigated for new potential applications of micro/nano MOFs. - Graphical abstract: Iron metal–organic frameworks (MOFs) [Fe(L){sub 2}(SCN){sub 2}]{sub ∝} (L1: 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadienemore » for 1Fe; and L2: 3-bpdh=2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene for 2Fe) were assembled in a MeOH–H{sub 2}O solvent system. The N-position within the pyridine ring of the complexes was observed to regulate the MOF structure as layers or chains. Selectively catalytic activity was observed for the layered MOF but not the chain-structured MOF. - Highlights: • Synthesis and structure of metal–organic framework [Fe(L){sub 2}(SCN){sub 2}]{sub ∝}. • Selectively catalytic activity depending on the N-position within the pyridine ring. • The degradation and conversion of methyl orange.« less

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.

Large Magnetoresistance at High Bias Voltage in Double-layer Organic Spin Valves

NASA Astrophysics Data System (ADS)

Subedi, R. C.; Liang, S. H.; Geng, R.; Zhang, Q. T.; Lou, L.; Wang, J.; Han, X. F.; Nguyen, T. D.

We report studies of magnetoresistance (MR) in double-layer organic spin valves (DOSV) using tris (8-hydroxyquinolinato) aluminum (Alq3) spacers. The device exhibits three distinct resistance levels depending on the relative magnetizations of the ferromagnetic electrodes. We observed a much weaker bias voltage dependence of MR in the device compared to that in the conventional organic spin valve (OSV). The MR magnitude reduces by the factor of two at 0.7 V bias voltage in the DOSV compared to 0.02 V in the conventional OSV. Remarkably, the MR magnitude reaches 0.3% at 6 V bias in the DOSVs, the largest MR response ever reported in OSVs at this bias. Our finding may have a significant impact on achieving high efficient bipolar OSVs strictly performed at high voltages. University of Georgia start-up fund, Ministry of Education, Singapore, National Natural Science Foundation of China.

Mechanically activated artificial cell by using microfluidics

NASA Astrophysics Data System (ADS)

Ho, Kenneth K. Y.; Lee, Lap Man; Liu, Allen P.

2016-09-01

All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology.

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.

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).

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.

Highly efficient and stable white organic light emitting diode base on double recombination zones of phosphorescent blue/orange emitters.

PubMed

Lee, Seok Jae; Koo, Ja Ryong; Lim, Dong Hwan; Park, Hye Rim; Kim, Young Kwan; Ha, Yunkyoung

2011-08-01

We demonstrated efficient and stable white phosphorescent organic light-emitting diodes (OLEDs) with double-emitting layers (D-EMLs), which were comprised of two emissive layers with a hole transport-type host of N,N'-dicarbazolyl-3,5-benzene (mCP) and a electron transport-type host of 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) with blue/orange emitters, respectively. We fabricated two type white devices with single emitting layer (S-EML) and D-EML of orange emitter, maintaining double recombination zone of blue emitter. In addition, the device architecture was developed to confine excitons inside the D-EMLs and to manage triplet excitons by controlling the charge injection. As a result, light-emitting performances of white OLED with D-EMLs were improved and showed the steady CIE coordinates compared to that with S-EML of orange emitter, which demonstrated the maximum luminous efficiency and external quantum efficiency were 21.38 cd/A and 11.09%. It also showed the stable white emission with CIE(x,y) coordinates from (x = 0.36, y = 0.37) at 6 V to (x = 0.33, y = 0.38) at 12 V.

Tunable electroluminescent color for 2, 5-diphenyl -1, 4-distyrylbenzene with two trans-double bonds

NASA Astrophysics Data System (ADS)

Cheng, Gang; Zhang, Yingfang; Zhao, Yi; Liu, Shiyong; Xie, Zengqi; Xia, Hong; Hanif, Muddasir; Ma, Yuguang

2005-07-01

Exciplex emission is observed in electroluminescent (EL) spectrum of an organic light-emitting device (OLED), where 2, 5-diphenyl -1, 4-distyrylbenzene with two trans-double bonds (trans-DPDSB), (8-hydroxyquinoline) aluminum, and N,N'-diphenyl-N,N'-bis(1-naphthyl)-(1,1'-biphenyl)-4,4'-diamine (NPB) are used as light-emitting, electron-transporting, and hole-transporting layers, respectively. This emission can be dramatically weakened by inserting a hole-injecting layer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) between the hole-transporting layer and the anode. Consequently, EL color of this OLED is tuned from white to blue. This phenomenon may result from the improvement of hole injection, which shifts the major recombination zone from the NPB/trans-DPDSB interface to the trans-DPDSB layer.

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.

Ultrashort-pulsed laser processing and solution based coating in roll-to-roll manufacturing of organic photovoltaics

NASA Astrophysics Data System (ADS)

Hördemann, C.; Hirschfelder, K.; Schaefer, M.; Gillner, A.

2015-09-01

The breakthrough of flexible organic electronics and especially organic photovoltaics is highly dependent on cost-efficient production technologies. Roll-2-Roll processes show potential for a promising solution in terms of high throughput and low-cost production of thin film organic components. Solution based material deposition and integrated laser patterning processes offer new possibilities for versatile production lines. The use of flexible polymeric substrates brings along challenges in laser patterning which have to be overcome. One main challenge when patterning transparent conductive layers on polymeric substrates are material bulges at the edges of the ablated area. Bulges can lead to short circuits in the layer system leading to device failure. Therefore following layers have to have a sufficient thickness to cover and smooth the ridge. In order to minimize the bulging height, a study has been carried out on transparent conductive ITO layers on flexible PET substrates. Ablation results using different beam shapes, such as Gaussian beam, Top-Hat beam and Donut-shaped beam, as well as multi-pass scribing and double-pulsed ablation are compared. Furthermore, lab scale methods for cleaning the patterned layer and eliminating bulges are contrasted to the use of additional water based sacrificial layers in order to obtain an alternative procedure suitable for large scale Roll-2-Roll manufacturing. Besides progress in research, ongoing transfer of laser processes into a Roll-2-Roll demonstrator is illustrated. By using fixed optical elements in combination with a galvanometric scanner, scribing, variable patterning and edge deletion can be performed individually.

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.

Self-organized layered hydrogenation in black Mg2NiHx switchable mirrors.

PubMed

Lohstroh, W; Westerwaal, R J; Noheda, B; Enache, S; Giebels, I A M E; Dam, B; Griessen, R

2004-11-05

In addition to a mirrorlike (Mg2Ni) and a transparent (Mg2NiH4) state, thin films of Mg2NiHx exhibit a remarkable black state with low reflection over the entire visible spectrum, essentially zero transmission and a low electrical resistivity. Such a black state is not explicable for a homogeneous layer since a large absorption coefficient always yields substantial reflection. We show that it results from a self-organized and reversible double layering of metallic Mg2NiH0.3 and semiconducting Mg2NiH4.

It Takes Two to Tango-Double-Layer Selective Contacts in Perovskite Solar Cells for Improved Device Performance and Reduced Hysteresis.

PubMed

Kegelmann, Lukas; Wolff, Christian M; Awino, Celline; Lang, Felix; Unger, Eva L; Korte, Lars; Dittrich, Thomas; Neher, Dieter; Rech, Bernd; Albrecht, Steve

2017-05-24

Solar cells made from inorganic-organic perovskites have gradually approached market requirements as their efficiency and stability have improved tremendously in recent years. Planar low-temperature processed perovskite solar cells are advantageous for possible large-scale production but are more prone to exhibiting photocurrent hysteresis, especially in the regular n-i-p structure. Here, a systematic characterization of different electron selective contacts with a variety of chemical and electrical properties in planar n-i-p devices processed below 180 °C is presented. The inorganic metal oxides TiO 2 and SnO 2 , the organic fullerene derivatives C 60 , PCBM, and ICMA, as well as double-layers with a metal oxide/PCBM structure are used as electron transport materials (ETMs). Perovskite layers deposited atop the different ETMs with the herein applied fabrication method show a similar morphology according to scanning electron microscopy. Further, surface photovoltage spectroscopy measurements indicate comparable perovskite absorber qualities on all ETMs, except TiO 2 , which shows a more prominent influence of defect states. Transient photoluminescence studies together with current-voltage scans over a broad range of scan speeds reveal faster charge extraction, less pronounced hysteresis effects, and higher efficiencies for devices with fullerene compared to those with metal oxide ETMs. Beyond this, only double-layer ETM structures substantially diminish hysteresis effects for all performed scan speeds and strongly enhance the power conversion efficiency up to a champion stabilized value of 18.0%. The results indicate reduced recombination losses for a double-layer TiO 2 /PCBM contact design: First, a reduction of shunt paths through the fullerene to the ITO layer. Second, an improved hole blocking by the wide band gap metal oxide. Third, decreased transport losses due to an energetically more favorable contact, as implied by photoelectron spectroscopy measurements. The herein demonstrated improvements of multilayer selective contacts may serve as a general design guideline for perovskite solar cells.

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.

Application of Organic Solid Electrolytes

NASA Technical Reports Server (NTRS)

Sekido, S.

1982-01-01

If ions are considered to be solid material which transport electric charges, polymer materials can then be considered as organic solid electrolytes. The role of these electrolytes is discussed for (1) ion concentration sensors; (2) batteries using lithium as the cathode and a charge complex of organic material and iodine in the anode; and (3) elements applying electrical double layer capability.

Effect of metal shielding on a wireless power transfer system

NASA Astrophysics Data System (ADS)

Li, Jiacheng; Huang, Xueliang; Chen, Chen; Tan, Linlin; Wang, Wei; Guo, Jinpeng

2017-05-01

In this paper, the effect of non-ferromagnetic metal shielding (NFMS) material on the resonator of wireless power transfer (WPT) is studied by modeling, simulation and experimental analysis. And, the effect of NFMS material on the power transfer efficiency (PTE) of WPT systems is investigated by circuit model. Meanwhile, the effect of ferromagnetic metal shielding material on the PTE of WPT systems is analyzed through simulation. A double layer metal shield structure is designed. Experimental results demonstrate that by applying the novel double layer metal shielding method, the system PTE increases significantly while the electromagnetic field of WPT systems declines dramatically.

The effect of gravity modulation on thermosolutal convection in an infinite layer of fluid

NASA Astrophysics Data System (ADS)

Saunders, B. V.; Murray, B. T.; McFadden, G. B.; Coriell, S. R.; Wheeler, A. A.

1992-06-01

The effect of time-periodic vertical gravity modulation on the onset of thermosolutal convection in an infinite horizontal layer with stress-free boundaries is investigated using Floquet theory for the linear stability analysis. Situations for which the fluid layer is stably stratified in either the fingering or diffusive regimes of double-diffusive convection are considered. Results are presented both with and without steady background acceleration. Modulation may stabilize an unstable base solution or destabilize a stable base solution. In addition to synchronous and subharmonic response to the modulation frequency, instability in the double diffusive system can occur via a complex conjugate mode. In the diffusive regime, where oscillatory onset occurs in the unmodulated system, regions of resonant instability occur and exhibit strong coupling with the unmodulated oscillatory frequency. The response to modulation of the fundamental instability of the unmodulated system is described both analytically and numerically; in the double-diffusive system this mode persists under subcritical conditions as a high-frequency lobe.

The effect of gravity modulation on thermosolutal convection in an infinite layer of fluid

NASA Technical Reports Server (NTRS)

Saunders, B. V.; Murray, B. T.; Mcfadden, G. B.; Coriell, S. R.; Wheeler, A. A.

1992-01-01

The effect of time-periodic vertical gravity modulation on the onset of thermosolutal convection in an infinite horizontal layer with stress-free boundaries is investigated using Floquet theory for the linear stability analysis. Situations for which the fluid layer is stably stratified in either the fingering or diffusive regimes of double-diffusive convection are considered. Results are presented both with and without steady background acceleration. Modulation may stabilize an unstable base solution or destabilize a stable base solution. In addition to synchronous and subharmonic response to the modulation frequency, instability in the double diffusive system can occur via a complex conjugate mode. In the diffusive regime, where oscillatory onset occurs in the unmodulated system, regions of resonant instability occur and exhibit strong coupling with the unmodulated oscillatory frequency. The response to modulation of the fundamental instability of the unmodulated system is described both analytically and numerically; in the double-diffusive system this mode persists under subcritical conditions as a high-frequency lobe.

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.

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.

Insights into the effects of solvent properties in graphene based electric double-layer capacitors with organic electrolytes

NASA Astrophysics Data System (ADS)

Zhang, Shuo; Bo, Zheng; Yang, Huachao; Yang, Jinyuan; Duan, Liangping; Yan, Jianhua; Cen, Kefa

2016-12-01

Organic electrolytes are widely used in electric double-layer capacitors (EDLCs). In this work, the microstructure of planar graphene-based EDLCs with different organic solvents are investigated with molecular dynamics simulations. Results show that an increase of solvent polarity could weaken the accumulation of counter-ions nearby the electrode surface, due to the screen of electrode charges and relatively lower ionic desolvation. It thus suggests that solvents with low polarity could be preferable to yield high EDL capacitance. Meanwhile, the significant effects of the size and structure of solvent molecules are reflected by non-electrostatic molecule-electrode interactions, further influencing the adsorption of solvent molecules on electrode surface. Compared with dimethyl carbonate, γ-butyrolactone, and propylene carbonate, acetonitrile with relatively small-size and linear structure owns weak non-electrostatic interactions, which favors the easy re-orientation of solvent molecules. Moreover, the shift of solvent orientation in surface layer, from parallel orientation to perpendicular orientation relative to the electrode surface, deciphers the solvent twin-peak behavior near negative electrode. The as-obtained insights into the roles of solvent properties on the interplays among particles and electrodes elucidate the solvent influences on the microstructure and capacitive behavior of EDLCs using organic electrolytes.

Some metal oxides and their applications for creation of Microsystems (MEMS) and Energy Harvesting Devices (EHD)

NASA Astrophysics Data System (ADS)

Denishev, K.

2016-10-01

This is a review of a part of the work of the Technological Design Group at Technical University of Sofia, Faculty of Electronic Engineering and Technologies, Department of Microelectronics. It is dealing with piezoelectric polymer materials and their application in different microsystems (MEMS) and Energy Harvesting Devices (EHD), some organic materials and their applications in organic (OLED) displays, some transparent conductive materials etc. The metal oxides Lead Zirconium Titanate (PZT) and Zinc Oxide (ZnO) are used as piezoelectric layers - driving part of different sensors, actuators and EHD. These materials are studied in term of their performance in dependence on the deposition conditions and parameters. They were deposited as thin films by using RF Sputtering System. As technological substrates, glass plates and Polyethylenetherephtalate (PET) foils were used. For characterization of the materials, a test structure, based on Surface Acoustic Waves (SAW), was designed and prepared. The layers were characterized by Fourier Transform Infrared spectroscopy (FTIR). The piezoelectric response was tested at variety of mechanical loads (tensile strain, stress) in static and dynamic (multiple bending) mode. The single-layered and double-layered structures were prepared for piezoelectric efficiency increase. A structure of piezoelectric energy transformer is proposed and investigated.

Anomalous Capacitance Maximum of the Glassy Carbon-Ionic Liquid Interface through Dilution with Organic Solvents.

PubMed

Bozym, David J; Uralcan, Betül; Limmer, David T; Pope, Michael A; Szamreta, Nicholas J; Debenedetti, Pablo G; Aksay, Ilhan A

2015-07-02

We use electrochemical impedance spectroscopy to measure the effect of diluting a hydrophobic room temperature ionic liquid with miscible organic solvents on the differential capacitance of the glassy carbon-electrolyte interface. We show that the minimum differential capacitance increases with dilution and reaches a maximum value at ionic liquid contents near 5-10 mol% (i.e., ∼1 M). We provide evidence that mixtures with 1,2-dichloroethane, a low-dielectric constant solvent, yield the largest gains in capacitance near the open circuit potential when compared against two traditional solvents, acetonitrile and propylene carbonate. To provide a fundamental basis for these observations, we use a coarse-grained model to relate structural variations at the double layer to the occurrence of the maximum. Our results reveal the potential for the enhancement of double-layer capacitance through dilution.

Maple prepared organic heterostructures for photovoltaic applications

NASA Astrophysics Data System (ADS)

Stanculescu, A.; Socol, M.; Socol, G.; Mihailescu, I. N.; Girtan, M.; Stanculescu, F.

2011-09-01

In this study, we present the deposition of ZnPc, Alq3, and PTCDA thin films using Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. We also report the realisation of multilayer structures, made by the successive application of MAPLE. The films have been characterized by spectroscopic (UV-VIS and Photoluminescence) and microscopic (SEM and AFM) methods, and the effect of different deposition conditions such as fluence, number of pulses, and target concentration on the properties has been analysed. This paper also presents some investigations on the electrical conduction in sandwich type structures ITO or Si/organic layer/Au or Cu and ITO/double organic layer/Cu, emphasising the dominant effect of the height of the energetic barriers at the inorganic/organic and organic/organic interfaces.

Lifetime Improvement of Organic Light Emitting Diodes using LiF Thin Film and UV Glue Encapsulation

NASA Astrophysics Data System (ADS)

Huang, Jian-Ji; Su, Yan-Kuin; Chang, Ming-Hua; Hsieh, Tsung-Eong; Huang, Bohr-Ran; Wang, Shun-Hsi; Chen, Wen-Ray; Tsai, Yu-Sheng; Hsieh, Huai-En; Liu, Mark O.; Juang, Fuh-Shyang

2008-07-01

This work demonstrates the use of lithium fluoride (LiF) as a passivation layer and a newly developed UV glue for encapsulation on the LiF passivation layer to enhance the stability of organic light-emitting devices (OLEDs). Devices with double protective layers showed a 25-fold increase in operational lifetime compared to those without any packaging layers. LiF has a low melting point and insulating characteristics and it can be adapted as both a protective layer and pre-encapsulation film. The newly developed UV glue has a fast curing time of only 6 s and can be directly spin-coated onto the surface of the LiF passivation layer. The LiF thin film plus spin-coated UV glue is a simple packaging method that reduces the fabrication costs of OLEDs.

The In Situ Enzymatic Screening (ISES) Approach to Reaction Discovery and Catalyst Identification.

PubMed

Swyka, Robert A; Berkowitz, David B

2017-12-14

The importance of discovering new chemical transformations and/or optimizing catalytic combinations has led to a flurry of activity in reaction screening. The in situ enzymatic screening (ISES) approach described here utilizes biological tools (enzymes/cofactors) to advance chemistry. The protocol interfaces an organic reaction layer with an adjacent aqueous layer containing reporting enzymes that act upon the organic reaction product, giving rise to a spectroscopic signal. ISES allows the experimentalist to rapidly glean information on the relative rates of a set of parallel organic/organometallic reactions under investigation, without the need to quench the reactions or draw aliquots. In certain cases, the real-time enzymatic readout also provides information on sense and magnitude of enantioselectivity and substrate specificity. This article contains protocols for single-well (relative rate) and double-well (relative rate/enantiomeric excess) ISES, in addition to a colorimetric ISES protocol and a miniaturized double-well procedure. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

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.

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.

Mechanisms of heat and mass transfer across a double-diffusive interface

NASA Astrophysics Data System (ADS)

Ko, B. H.; Smith, K. A.

1984-06-01

Flux measurements in an aqueous two-layer double-diffusive system using heat and NaCl confirmed the existence of a regime in which the ratio of the buoyancy fluxes (BFR) of salt and heat is independent of the stability ratio (R = beta(delta C)/alpha(delta T)). Linear analysis showed that the quiescent system can become unstable to small perturbations even when the lower layer is denser than the upper. If R is large, the most unstable mode presents as an oscillatory, antisymmetric pattern.

Three-dimensionally arrayed and mutually connected 1.2-nm nanopores for high-performance electric double layer capacitor.

PubMed

Itoi, Hiroyuki; Nishihara, Hirotomo; Kogure, Taichi; Kyotani, Takashi

2011-02-09

Zeolite-templated carbon is a promising candidate as an electrode material for constructing an electric double layer capacitor with both high-power and high-energy densities, due to its three-dimensionally arrayed and mutually connected 1.2-nm nanopores. This carbon exhibits both very high gravimetric (140-190 F g(-1)) and volumetric (75-83 F cm(-3)) capacitances in an organic electrolyte solution. Moreover, such a high capacitance can be well retained even at a very high current up to 20 A g(-1). This extraordinary high performance is attributed to the unique pore structure.

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

Metal-free aqueous redox capacitor via proton rocking-chair system in an organic-based couple

PubMed Central

Tomai, Takaaki; Mitani, Satoshi; Komatsu, Daiki; Kawaguchi, Yuji; Honma, Itaru

2014-01-01

Safe and inexpensive energy storage devices with long cycle lifetimes and high power and energy densities are mandatory for the development of electrical power grids that connect with renewable energy sources. In this study, we demonstrated metal-free aqueous redox capacitors using couples comprising low-molecular-weight organic compounds. In addition to the electric double layer formation, proton insertion/extraction reactions between a couple consisting of inexpensive quinones/hydroquinones contributed to the energy storage. This energy storage mechanism, in which protons are shuttled back and forth between two electrodes upon charge and discharge, can be regarded as a proton rocking-chair system. The fabricated capacitor showed a large capacity (>20 Wh/kg), even in the applied potential range between 0–1 V, and high power capability (>5 A/g). The support of the organic compounds in nanoporous carbon facilitated the efficient use of the organic compounds with a lifetime of thousands of cycles. PMID:24395117

Metal-free aqueous redox capacitor via proton rocking-chair system in an organic-based couple.

PubMed

Tomai, Takaaki; Mitani, Satoshi; Komatsu, Daiki; Kawaguchi, Yuji; Honma, Itaru

2014-01-07

Safe and inexpensive energy storage devices with long cycle lifetimes and high power and energy densities are mandatory for the development of electrical power grids that connect with renewable energy sources. In this study, we demonstrated metal-free aqueous redox capacitors using couples comprising low-molecular-weight organic compounds. In addition to the electric double layer formation, proton insertion/extraction reactions between a couple consisting of inexpensive quinones/hydroquinones contributed to the energy storage. This energy storage mechanism, in which protons are shuttled back and forth between two electrodes upon charge and discharge, can be regarded as a proton rocking-chair system. The fabricated capacitor showed a large capacity (>20 Wh/kg), even in the applied potential range between 0-1 V, and high power capability (>5 A/g). The support of the organic compounds in nanoporous carbon facilitated the efficient use of the organic compounds with a lifetime of thousands of cycles.

Metal-free aqueous redox capacitor via proton rocking-chair system in an organic-based couple

NASA Astrophysics Data System (ADS)

Tomai, Takaaki; Mitani, Satoshi; Komatsu, Daiki; Kawaguchi, Yuji; Honma, Itaru

2014-01-01

Safe and inexpensive energy storage devices with long cycle lifetimes and high power and energy densities are mandatory for the development of electrical power grids that connect with renewable energy sources. In this study, we demonstrated metal-free aqueous redox capacitors using couples comprising low-molecular-weight organic compounds. In addition to the electric double layer formation, proton insertion/extraction reactions between a couple consisting of inexpensive quinones/hydroquinones contributed to the energy storage. This energy storage mechanism, in which protons are shuttled back and forth between two electrodes upon charge and discharge, can be regarded as a proton rocking-chair system. The fabricated capacitor showed a large capacity (>20 Wh/kg), even in the applied potential range between 0-1 V, and high power capability (>5 A/g). The support of the organic compounds in nanoporous carbon facilitated the efficient use of the organic compounds with a lifetime of thousands of cycles.

Optimum design for effective water transport through a double-layered porous hydrogel inspired by plant leaves

NASA Astrophysics Data System (ADS)

Kim, Hyejeong; Kim, Hyeonjeong; Huh, Hyungkyu; Hwang, Hyung Ju; Lee, Sang Joon

2014-11-01

Plant leaves are generally known to have optimized morphological structure in response to environmental changes for efficient water usage. However, the advantageous features of plant leaves are not fully utilized in engineering fields yet, since the optimum design in internal structure of plant leaves is unclear. In this study, the tissue organization of the hydraulic pathways inside plant leaves was investigated. Water transport through double-layered porous hydrogel models analogous to mesophyll cells was experimentally observed. In addition, computational experiment and theoretical analysis were applied to the model systems to find the optimal design for efficient water transport. As a result, the models with lower porosity or with pores distributed widely in the structure exhibit efficient mass transport. Our theoretical prediction supports that structural features of plant leaves guarantee sufficient water supply as survival strategy. This study may provide a new framework for investigating the biophysical principles governing the morphological optimization of plant leaves and for designing microfluidic devices to enhance mass transport ability. This study was supported by the National Research Foundation of Korea and funded by the Korean government.

Double-Diffusive Convection at Low Prandtl Number

NASA Astrophysics Data System (ADS)

Garaud, Pascale

2018-01-01

This work reviews present knowledge of double-diffusive convection at low Prandtl number obtained using direct numerical simulations, in both the fingering regime and the oscillatory regime. Particular emphasis is given to modeling the induced turbulent mixing and its impact in various astrophysical applications. The nonlinear saturation of fingering convection at low Prandtl number usually drives small-scale turbulent motions whose transport properties can be predicted reasonably accurately using a simple semi-analytical model. In some instances, large-scale internal gravity waves can be excited by a collective instability and eventually cause layering. The nonlinear saturation of oscillatory double-diffusive convection exhibits much more complex behavior. Weakly stratified systems always spontaneously transition into layered convection associated with very efficient mixing. More strongly stratified systems remain dominated by weak wave turbulence unless they are initialized into a layered state. The effects of rotation, shear, lateral gradients, and magnetic fields are briefly discussed.

Electrical power generation by mechanically modulating electrical double layers.

PubMed

Moon, Jong Kyun; Jeong, Jaeki; Lee, Dongyun; Pak, Hyuk Kyu

2013-01-01

Since Michael Faraday and Joseph Henry made their great discovery of electromagnetic induction, there have been continuous developments in electrical power generation. Most people today get electricity from thermal, hydroelectric, or nuclear power generation systems, which use this electromagnetic induction phenomenon. Here we propose a new method for electrical power generation, without using electromagnetic induction, by mechanically modulating the electrical double layers at the interfacial areas of a water bridge between two conducting plates. We find that when the height of the water bridge is mechanically modulated, the electrical double layer capacitors formed on the two interfacial areas are continuously charged and discharged at different phases from each other, thus generating an AC electric current across the plates. We use a resistor-capacitor circuit model to explain the results of this experiment. This observation could be useful for constructing a micro-fluidic power generation system in the near future.

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.

Preparation, physicochemical characterisation and magnetic properties of Cu-Al layered double hydroxides with CO 32- and anionic surfactants with different alkyl chains in the interlayer

NASA Astrophysics Data System (ADS)

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

2006-03-01

Layered double hydroxides with the hydrotalcite-like structure, containing Cu(II) and Al(III) in the layers, and different alkyl sulphonates in the interlayer, have been prepared and characterised by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Their magnetic properties have been also studied. Except for the sample containing octadecanesulphonate in the interlayer, for which an excess of sulphonate exists, pure crystalline phases have been obtained in the other cases. Upon heating, combustion of the organic chain takes place at lower temperature than for the corresponding sodium salts. A two-dimensional antiferromagnetic behaviour is observed at 200 K in all samples containing intercalated sulphonate. The χT value is lower for the samples containing interlayer sulphonates (with layer-layer distances in the 21-31 Å range), than for a carbonate-containing analogue (basal spacing 7.51 Å).

Effects of interfacial stability between electron transporting layer and cathode on the degradation process of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Chu, Ta-Ya; Lee, Yong-Han; Song, Ok-Keun

2007-11-01

The authors have demonstrated that the increase of electron injection barrier height between tris(8-hydroxyquinoline)aluminum (Alq3) and LiF /Al cathode is one of the most critical parameters to determine the reliability of organic light-emitting diode with the typical structure of indium tin oxide/N ,N'-bis(naphthalen-1-yl)-N ,N'-bis(phenyl) benzidine/Alq3/LiF /Al. The electrical properties of several devices (hole only, electron only, and integrated double-layered devices) have been measured in the function of operating time to analyze the bulk and interface property changes. Bulk properties of trap energy and mobility in an organic layer have been estimated by using trap-charge-limited currents and transient electroluminescence measurements.

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.

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

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.

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.

[Effects of different winter cover crops on soil organic carbon in a double cropping rice paddy field.

PubMed

Tang, Hai Ming; Cheng, Kai Kai; Xiao, Xiao Ping; Tang, Wen Guang; Wang, Ke; Li, Chao; Zhang, Fan; Sun, Yu Tao

2017-02-01

In a double cropping rice field experiment, effects of five winter cover crops on the total organic carbon (TOC), active organic carbon (AOC), carbon pool management index (CPMI) and organic carbon storage were studied in three soil layers (0-5, 5-10 and 10-20 cm).Winter cover crops of ryegrass (Ry), Chinese milk vetch (Mv), potato (Po), and rape (Ra) between two rice crops were compared with fallow as control (CK). The results showed that the TOC and AOC contents under Ry, Mv, Po and Ra treatments were higher than those of CK in all three la-yers. Meanwhile, the TOC and AOC contents in Po treatment were higher than those of other treatments. Compared with CK, the AOC, activity index (AI), carbon pool index (CPI) and CPMI in the soil were improved through the recycling of winter cover crops straw. The AOC, AI, CPI and CPMI in the studied layers increased in order of Po>Mv>Ry>Ra>CK. The results indicated that the recycling of winter cover crops straw promoted the storage of SOC in the 0-20 cm soil profile as compared with CK. The strongest effect of the winter cover crops on the SOC storage occurred in Mv treatment, followed by Mv and Po treatments, and the SOC storage increased with the increasing soil depth.

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.

Efficient red organic electroluminescent devices by doping platinum(II) Schiff base emitter into two host materials with stepwise energy levels.

PubMed

Zhou, Liang; Kwok, Chi-Chung; Cheng, Gang; Zhang, Hongjie; Che, Chi-Ming

2013-07-15

In this work, organic electroluminescent (EL) devices with double light-emitting layers (EMLs) having stepwise energy levels were designed to improve the EL performance of a red-light-emitting platinum(II) Schiff base complex. A series of devices with single or double EML(s) were fabricated and characterized. Compared with single-EML devices, double-EML devices showed improved EL efficiency and brightness, attributed to better balance in carriers. In addition, the stepwise distribution in energy levels of host materials is instrumental in broadening the recombination zone, thus delaying the roll-off of EL efficiency. The highest EL current efficiency and power efficiency of 17.36 cd/A and 14.73 lm/W, respectively, were achieved with the optimized double-EML devices. At high brightness of 1000 cd/m², EL efficiency as high as 8.89 cd/A was retained.

Container lid gasket protective strip for double door transfer system

DOEpatents

Allen, Jr., Burgess M

2013-02-19

An apparatus and a process for forming a protective barrier seal along a "ring of concern" of a transfer container used with double door systems is provided. A protective substrate is supplied between a "ring of concern" and a safety cover in which an adhesive layer of the substrate engages the "ring of concern". A compressive foam strip along an opposite side of the substrate engages a safety cover such that a compressive force is maintained between the "ring of concern" and the adhesive layer of the substrate.

Artificial Synaptic Devices Based on Natural Chicken Albumen Coupled Electric-Double-Layer Transistors

NASA Astrophysics Data System (ADS)

Wu, Guodong; Feng, Ping; Wan, Xiang; Zhu, Liqiang; Shi, Yi; Wan, Qing

2016-03-01

Recent progress in using biomaterials to fabricate functional electronics has got growing attention for the new generation of environmentally friendly and biocompatible electronic devices. As a kind of biological material with rich source, proteins are essential natural component of all organisms. At the same time, artificial synaptic devices are of great significance for neuromorphic systems because they can emulate the signal process and memory behaviors of biological synapses. In this report, natural chicken albumen with high proton conductivity was used as the coupling electrolyte film for organic/inorganic hybrid synaptic devices fabrication. Some important synaptic functions including paired-pulse facilitation, dynamic filtering, short-term to long-term memory transition and spatial summation and shunting inhibition were successfully mimicked. Our results are very interesting for biological friendly artificial neuron networks and neuromorphic systems.

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.

A polygonal double-layer coil design for high-efficiency wireless power transfer

NASA Astrophysics Data System (ADS)

Mao, Shitong; Wang, Hao; Mao, Zhi-Hong; Sun, Mingui

2018-05-01

In this work, we present a novel coil structure for the design of Wireless Power Transfer (WPT) systems via magnetic resonant coupling. The new coil consists of two layers of flat polygonal windings in square, pentagonal and hexagonal shapes. The double-layer coil can be conveniently fabricated using the print circuit broad (PCB) technology. In our design, we include an angle between the two layers which can be adjusted to change the area of inter-layer overlap. This unique structure is thoroughly investigated with respect to the quality factor Q and the power transfer efficiency (PTE) using the finite element method (FEM). An equivalent circuit is derived and used to explain the properties of the angularly shifted double-layer coil theoretically. Comparative experiments are conducted from which the performance of the new coil is evaluated quantitatively. Our results have shown that an increased shift angle improves the Q-factor, and the optimal PTE is achieved when the angle reaches the maximum. When compared to the pentagonal and hexagonal coils, the square coil achieves the highest PTE due to its lowest parasitic capacitive effects. In summary, our new coil design improves the performance of WPT systems and allows a formal design procedure for optimization in a given application.

Electrosorption capacitance of nanostructured carbon-based materials.

PubMed

Hou, Chia-Hung; Liang, Chengdu; Yiacoumi, Sotira; Dai, Sheng; Tsouris, Costas

2006-10-01

The fundamental mechanism of electrosorption of ions developing a double layer inside nanopores was studied via a combination of experimental and theoretical studies. A novel graphitized-carbon monolithic material has proven to be a good electrical double-layer capacitor that can be applied in the separation of ions from aqueous solutions. An extended electrical double-layer model indicated that the pore size distribution plays a key role in determining the double-layer capacitance in an electrosorption process. Because of the occurrence of double-layer overlapping in narrow pores, mesopores and micropores make significantly different contributions to the double-layer capacitance. Mesopores show good electrochemical accessibility. Micropores present a slow mass transfer of ions and a considerable loss of double-layer capacitance, associated with a shallow potential distribution inside pores. The formation of the diffuse layer inside the micropores determines the magnitude of the double-layer capacitance at low electrolyte concentrations and at conditions close to the point of zero charge of the material. The effect of the double-layer overlapping on the electrosorption capacitance can be reduced by increasing the pore size, electrolyte concentration, and applied potential. The results are relevant to water deionization.

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.

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

Explosive Magnetic Reconnection in Double-current Sheet Systems: Ideal versus Resistive Tearing Mode

NASA Astrophysics Data System (ADS)

Baty, Hubert

2017-03-01

Magnetic reconnection associated with the tearing instability occurring in double-current sheet systems is investigated within the framework of resistive magnetohydrodynamics (MHD) in a two-dimensional Cartesian geometry. A special emphasis on the existence of fast and explosive phases is taken. First, we extend the recent theory on the ideal tearing mode of a single-current sheet to a double-current layer configuration. A linear stability analysis shows that, in long and thin systems with (length to shear layer thickness) aspect ratios scaling as {S}L9/29 (S L being the Lundquist number based on the length scale L), tearing modes can develop on a fast Alfvénic timescale in the asymptotic limit {S}L\\to ∞ . The linear results are confirmed by means of compressible resistive MHD simulations at relatively high S L values (up to 3× {10}6) for different current sheet separations. Moreover, the nonlinear evolution of the ideal double tearing mode (IDTM) exhibits a richer dynamical behavior than its single-tearing counterpart, as a nonlinear explosive growth violently ends up with a disruption when the two current layers interact trough the merging of plasmoids. The final outcome of the system is a relaxation toward a new state, free of magnetic field reversal. The IDTM dynamics is also compared to the resistive double tearing mode dynamics, which develops in similar systems with smaller aspect ratios, ≳ 2π , and exhibits an explosive secondary reconnection, following an initial slow resistive growth phase. Finally, our results are used to discuss the flaring activity in astrophysical magnetically dominated plasmas, with a particular emphasis on pulsar systems.

Anionic poly(p-phenylenevinylene)/layered double hydroxide ordered ultrathin films with multiple quantum well structure: a combined experimental and theoretical study.

PubMed

Yan, Dongpeng; Lu, Jun; Ma, Jing; Wei, Min; Wang, Xinrui; Evans, David G; Duan, Xue

2010-05-18

The sulfonated phenylenevinylene polyanion derivate (APPV) and exfoliated Mg-Al-layered double hydroxide (LDH) monolayers were alternatively assembled into ordered ultrathin films (UTFs) employing a layer-by-layer method, which shows uniform yellow luminescence. UV-vis absorption and fluorescence spectroscopy present a stepwise and regular growth of the UTFs upon increasing deposited cycles. X-ray diffraction, atomic force microscopy, and scanning electron microscopy demonstrate that the UTFs are orderly periodical layered structure with a thickness of 3.3-3.5 nm per bilayer. The APPV/LDH UTFs exhibit well-defined polarized photoemission characteristic with the maximum luminescence anisotropy of approximately 0.3. Moreover, the UTF exhibit longer fluorescence lifetime (3-3.85-fold) and higher photostability than the drop-casting APPV film under UV irradiation, suggesting that the existence of a LDH monolayer enhances the optical performance of the APPV polyanion. A combination study of electrochemistry and periodic density functional theory was used to investigate the electronic structure of the APPV/LDH system, illustrating that the APPV/LDH UTF is a kind of organic-inorganic hybrid multiple quantum well (MQW) structure with a low band energy of 1.7-1.8 eV, where the valence electrons of APPV can be confined into the energy wells formed by the LDH monolayers effectively. Therefore, this work not only gives a feasible method for fabricating a luminescence ultrathin film but also provides a detailed understanding of the geometric and electronic structures of photoactive polyanions confined between the LDH monolayers.

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

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.

Double Bright Band Observations with High-Resolution Vertically Pointing Radar, Lidar, and Profiles

NASA Technical Reports Server (NTRS)

Emory, Amber E.; Demoz, Belay; Vermeesch, Kevin; Hicks, Michael

2014-01-01

On 11 May 2010, an elevated temperature inversion associated with an approaching warm front produced two melting layers simultaneously, which resulted in two distinct bright bands as viewed from the ER-2 Doppler radar system, a vertically pointing, coherent X band radar located in Greenbelt, MD. Due to the high temporal resolution of this radar system, an increase in altitude of the melting layer of approximately 1.2 km in the time span of 4 min was captured. The double bright band feature remained evident for approximately 17 min, until the lower atmosphere warmed enough to dissipate the lower melting layer. This case shows the relatively rapid evolution of freezing levels in response to an advancing warm front over a 2 h time period and the descent of an elevated warm air mass with time. Although observations of double bright bands are somewhat rare, the ability to identify this phenomenon is important for rainfall estimation from spaceborne sensors because algorithms employing the restriction of a radar bright band to a constant height, especially when sampling across frontal systems, will limit the ability to accurately estimate rainfall.

Double bright band observations with high-resolution vertically pointing radar, lidar, and profilers

NASA Astrophysics Data System (ADS)

Emory, Amber E.; Demoz, Belay; Vermeesch, Kevin; Hicks, Micheal

2014-07-01

On 11 May 2010, an elevated temperature inversion associated with an approaching warm front produced two melting layers simultaneously, which resulted in two distinct bright bands as viewed from the ER-2 Doppler radar system, a vertically pointing, coherent X band radar located in Greenbelt, MD. Due to the high temporal resolution of this radar system, an increase in altitude of the melting layer of approximately 1.2 km in the time span of 4 min was captured. The double bright band feature remained evident for approximately 17 min, until the lower atmosphere warmed enough to dissipate the lower melting layer. This case shows the relatively rapid evolution of freezing levels in response to an advancing warm front over a 2 h time period and the descent of an elevated warm air mass with time. Although observations of double bright bands are somewhat rare, the ability to identify this phenomenon is important for rainfall estimation from spaceborne sensors because algorithms employing the restriction of a radar bright band to a constant height, especially when sampling across frontal systems, will limit the ability to accurately estimate rainfall.

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

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

Entropic effects in the electric double layer of model colloids with size-asymmetric monovalent ions

NASA Astrophysics Data System (ADS)

Guerrero-García, Guillermo Iván; González-Tovar, Enrique; Olvera de la Cruz, Mónica

2011-08-01

The structure of the electric double layer of charged nanoparticles and colloids in monovalent salts is crucial to determine their thermodynamics, solubility, and polyion adsorption. In this work, we explore the double layer structure and the possibility of charge reversal in relation to the size of both counterions and coions. We examine systems with various size-ratios between counterions and coions (ion size asymmetries) as well as different total ion volume fractions. Using Monte Carlo simulations and integral equations of a primitive-model electric double layer, we determine the highest charge neutralization and electrostatic screening near the electrified surface. Specifically, for two binary monovalent electrolytes with the same counterion properties but differing only in the coion's size surrounding a charged nanoparticle, the one with largest coion size is found to have the largest charge neutralization and screening. That is, in size-asymmetric double layers with a given counterion's size the excluded volume of the coions dictates the adsorption of the ionic charge close to the colloidal surface for monovalent salts. Furthermore, we demonstrate that charge reversal can occur at low surface charge densities, given a large enough total ion concentration, for systems of monovalent salts in a wide range of ion size asymmetries. In addition, we find a non-monotonic behavior for the corresponding maximum charge reversal, as a function of the colloidal bare charge. We also find that the reversal effect disappears for binary salts with large-size counterions and small-size coions at high surface charge densities. Lastly, we observe a good agreement between results from both Monte Carlo simulations and the integral equation theory across different colloidal charge densities and 1:1-elec-trolytes with different ion sizes.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

NASA Astrophysics Data System (ADS)

Hanis Tajuddin, Muhammad; Yusof, Norhaniza; Salleh, Wan Norharyati Wan; Fauzi Ismail, Ahmad; Hanis Hayati Hairom, Nur; Misdan, Nurasyikin

2018-03-01

Thin film nanocomposite (TFN) membrane with copper-aluminium layered double hydroxides (LDH) incorporated into polyamide (PA) selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC) in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4) removal and compared with thin film composite (TFC). The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Effects of emission layer doping on the spatial distribution of charge and host recombination rate density in organic light emitting devices: A numerical study

NASA Astrophysics Data System (ADS)

Li, Yanli; Zhou, Maoqing; Zheng, Tingcai; Yao, Bo; Peng, Yingquan

2013-12-01

Based on drift-diffusion theory, a numerical model of the doping of a single energy level trap in the emission layer of an organic light emitting device (OLED) was developed, and the effects of doping of this single energy level trap on the distribution of the charge density, the recombination rate density, and the electric field in single- and double-layer OLEDs were studied numerically. The results show that by doping the n-type (p-type) emission layer with single energy electron (hole) traps, the distribution of the recombination rate density can be tuned and shifted, which is useful for improvement of the device performance by reduced electrode quenching or for realization of desirable special functions, e.g., emission spectrum tuning in multiple dye-doped white OLEDs.

Hybrid Structure White Organic Light Emitting Diode for Enhanced Efficiency by Varied Doping Rate.

PubMed

Kim, Dong-Eun; Kang, Min-Jae; Park, Gwang-Ryeol; Kim, Nam-Kyu; Lee, Burm-Jong; Kwon, Young-Soo; Shin, Hoon-Kyu

2016-03-01

Novel materials based on Zn(HPB)2 and Ir-complexes were synthesized as blue or red emitters, respectively. White organic light emitting diodes were fabricated using the Zn(HPB)2 as a blue emitting layer, Ir-complexes as a red emitting layer and Alq3 as a green emitting layer. The obtained experimental results, were based on white OLEDs fabricated using double emission layers of Zn(HPB)2 and Alq3:Ir-complexes. The doping rate of the Ir-complexes was varied at 0.4%, 0.6%, 0.8% and 1.0%. When the doping rate of the Alq3:Ir-complexes was 0.6%, a white emission was achieved. The Commission Internationale de l'Eclairage coordinates of the device's white emission were (0.316, 0.331) at an applied voltage of 10.75 V.

Mathematical modeling of influence of ion size effects in an electrolyte in a nanoslit with overlapped EDL

NASA Astrophysics Data System (ADS)

Rajni, Kumar, Prashant

2017-10-01

Many nanofluidic systems are being used in a wide range of applications due to advances in nanotechnology. Due to nanoscale size of the system, the physics involved in the electric double layer and consequently the different phenomena related to it are different than those at microscale. The Poisson-Boltzmann equation governing the electric double layer in the system has many shortcomings such as point sized ions. The inclusion of finite size of ions give rise to various electrokinetic phenomena. Electrocapillarity is one such phenomena where the size effect plays an important role. Theeffect of asymmetric finite ion sizes in nano-confinement in the view of osmotic pressure and electrocapillarity is analyzed. As the confinement width of the system becomes comparable with the Debye length, the overlapped electric double layer (EDL) is influenced and significantly deformed by the steric effects. The osmotic pressure from the modified Poisson-Boltzmann equation in nanoslit is obtained. Due to nonlinear nature of the modified PB equation, the solution is obtained through numerical method. Afterwards, the electrocapillarity due to the steric effect is analyzed under constant surface potential condition at the walls of the nanoslit along with the flat interface assumption.

The double-layer of penetrable ions: an alternative route to charge reversal.

PubMed

Frydel, Derek; Levin, Yan

2013-05-07

We investigate a double-layer of penetrable ions near a charged wall. We find a new mechanism for charge reversal that occurs in the weak-coupling regime and, accordingly, the system is suitable for the mean-field analysis. The penetrability is achieved by smearing-out the ionic charge inside a sphere, so there is no need to introduce non-electrostatic forces and the system in the low coupling limit can be described by a modified version of the Poisson-Boltzmann equation. The predictions of the theory are compared with the Monte Carlo simulations.

Laboratory Layered Latte

NASA Astrophysics Data System (ADS)

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

2017-11-01

Layered composite fluids are sometimes observed in confined systems of rather chaotic initial states, for example, layered lattes formed by pouring espresso into a glass of warm milk. In such configurations, pouring forces a lower density liquid (espresso) into a higher density ambient, which is similar to the fountain effects that characterize a wide range of flows driven by injecting a fluid into a second miscible phase. Although the initial state of the mixture is complex and chaotic, there are conditions where the mixture cools at room temperature and exhibits an organized layered pattern. Here we report controlled experiments injecting a fluid into a miscible phase and show that, above a critical injection velocity, layering naturally emerges over the time scale of minutes. We perform experimental and numerical analyses of the time-dependent flows to observe and understand the convective circulation in the layers. We identify critical conditions to produce the layering and relate the results quantitatively to the critical Rayleigh number in double-diffusive convection, which indicates the competition between the horizontal thermal gradient and the vertical density gradient generated by the fluid injection. 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 as well as the local material concentration vary step-wise along the length of the material.

Composition driven monolayer to bilayer transformation in a surfactant intercalated Mg-Al layered double hydroxide.

PubMed

Naik, Vikrant V; Chalasani, Rajesh; Vasudevan, S

2011-03-15

The structure and organization of dodecyl sulfate (DDS) surfactant chains intercalated in an Mg-Al layered double hydroxide (LDH), Mg(1-x)Alx(OH)2, with differing Al/Mg ratios has been investigated. The Mg-Al LDHs can be prepared over a range of compositions with x varying from 0.167 to 0.37 and therefore provides a simple system to study how the organization of the alkyl chains of the intercalated DDS anions change with packing density; the Al/Mg ratio or x providing a convenient handle to do so. Powder X-ray diffraction measurements showed that at high packing densities (x ≥ 0.3) the alkyl chains of the intercalated dodecyl sulfate ions are anchored on opposing LDH sheets and arranged as bilayers with an interlayer spacing of ∼27 Å. At lower packing densities (x < 0.2) the surfactant chains form a monolayer with the alkyl chains oriented flat in the galleries with an interlayer spacing of ∼8 Å. For the in between compositions, 0.2 ≤ x < 0.3, the material is biphasic. MD simulations were performed to understand how the anchoring density of the intercalated surfactant chains in the Mg-Al LDH-DDS affects the organization of the chains and the interlayer spacing. The simulations are able to reproduce the composition driven monolayer to bilayer transformation in the arrangement of the intercalated surfactant chains and in addition provide insights into the factors that decide the arrangement of the surfactant chains in the two situations. In the bilayer arrangement, it is the dispersive van der Waals interactions between chains in opposing layers of the anchored bilayer that is responsible for the cohesive energy of the solid whereas at lower packing densities, where a monolayer arrangement is favored, Coulomb interactions between the positively charged Mg-Al LDH sheets and the negatively charged headgroup of the DDS anion dominate.

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.

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.

Interactions and Supramolecular Organization of Sulfonated Indigo and Thioindigo Dyes in Layered Hydroxide Hosts.

PubMed

Costa, Ana L; Gomes, Ana C; Pereira, Ricardo C; Pillinger, Martyn; Gonçalves, Isabel S; Pineiro, Marta; Seixas de Melo, J Sérgio

2018-01-09

Supramolecularly organized host-guest systems have been synthesized by intercalating water-soluble forms of indigo (indigo carmine, IC) and thioindigo (thioindigo-5,5'-disulfonate, TIS) in zinc-aluminum-layered double hydroxides (LDHs) and zinc-layered hydroxide salts (LHSs) by coprecipitation routes. The colors of the isolated powders were dark blue for hybrids containing only IC, purplish blue or dark lilac for cointercalated samples containing both dyes, and ruby/wine for hybrids containing only TIS. The as-synthesized and thermally treated materials were characterized by Fourier transform infrared, Fourier transform Raman, and nuclear magnetic resonance spectroscopies, powder X-ray diffraction, scanning electron microscopy, and elemental and thermogravimetric analyses. The basal spacings found for IC-LDH, TIS-LDH, IC-LHS, and TIS-LHS materials were 21.9, 21.05, 18.95, and 21.00 Å, respectively, with intermediate spacings being observed for the cointercalated samples that either decreased (LDHs) or increased (LHSs) with increasing TIS content. UV-visible and fluorescence spectroscopies (steady-state and time-resolved) were used to probe the molecular distribution of the immobilized dyes. The presence of aggregates together with the monomer units is suggested for IC-LDH, whereas for TIS-LDH, IC-LHS, and TIS-LHS, the dyes are closer to the isolated situation. Accordingly, while emission from the powder H 2 TIS is strongly quenched, an increment in the emission of about 1 order of magnitude was observed for the TIS-LDH/LHS hybrids. Double-exponential fluorescence decays were obtained and associated with two monomer species interacting differently with cointercalated water molecules. The incorporation of both TIS and IC in the LDH and LHS hosts leads to an almost complete quenching of the fluorescence, pointing to a very efficient energy transfer process from (fluorescent) TIS to (nonfluorescent) IC.

A critical time window for organismal interactions in a pelagic ecosystem.

PubMed

Benoit-Bird, Kelly J; McManus, Margaret A

2014-01-01

To measure organismal coherence in a pelagic ecosystem, we used moored sensors to describe the vertical dynamics of each step in the food chain in shelf waters off the west shore of Oahu, Hawaii. Horizontally extensive, intense aggregations of phytoplankton, zooplankton, and micronekton exhibited strong diel patterns in abundance and vertical distribution, resulting in a highly variable potential for interaction amongst trophic levels. Only around dusk did zooplankton layers overlap with phytoplankton layers. Shortly after sunset, micronekton ascended from the deep, aggregating on the island's shelf. Short-lived departures in migration patterns were detected in depth, vertical distribution, density, and total abundance of micronekton when zooplankton layers were present with typical patterns resuming within one hour. Layers of zooplankton began to disappear within 20 minutes of the arrival of micronekton with no layers present after 50 minutes. The effects of zooplankton layers cascaded even further up the food chain, affecting many behaviors of dolphins observed at dusk including their depth, group size, and inter-individual spacing. As a result of these changes in behavior, during a 30-minute window just after dusk, the number of feeding events observed for each dolphin and consequently the feeding time for each individual more than doubled when zooplankton layers were present. Dusk is a critical period for interactions amongst species in this system from phytoplankton to top predators. Our observations that short time windows can drive the structure and function of a complex suite of organisms highlight the importance of explicitly adding a temporal dimension at a scale relevant to individual organisms to our descriptions of heterogeneity in ocean ecosystems.

Benard and Marangoni convection in multiple liquid layers

NASA Technical Reports Server (NTRS)

Koster, Jean N.; Prakash, A.; Fujita, D.; Doi, T.

1992-01-01

Convective fluid dynamics of immiscible double and triple liquid layers are considered. First results on multilayer convective flow, in preparation for spaceflight experiment aboard IML-2 (International Microgravity Laboratory), are discussed. Convective flow in liquid layers with one or two horizontal interfaces with heat flow applied parallel to them is one of the systems investigated. The second system comprises two horizontally layered immiscible liquids heated from below and cooled from above, that is, heat flow orthogonal to the interface. In this system convection results due to the classical Benard instability.

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.

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.

Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

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

Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in; Sekar Iyengar, A. N.

It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leadsmore » to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.« less

Automated solid-phase extraction of phenolic acids using layered double hydroxide-alumina-polymer disks.

PubMed

Ghani, Milad; Palomino Cabello, Carlos; Saraji, Mohammad; Manuel Estela, Jose; Cerdà, Víctor; Turnes Palomino, Gemma; Maya, Fernando

2018-01-26

The application of layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disks for solid-phase extraction is reported for the first time. Al 2 O 3 is embedded in a polymer matrix followed by an in situ metal-exchange process to obtain a layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disk with excellent flow-through properties. The extraction performance of the prepared disks is evaluated as a proof of concept for the automated extraction using sequential injection analysis of organic acids (p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, gallic acid) following an anion-exchange mechanism. After the solid-phase extraction, phenolic acids were quantified by reversed-phase high-performance liquid chromatography with diode-array detection using a core-shell silica-C18 stationary phase and isocratic elution (acetonitrile/0.5% acetic acid in pure water, 5:95, v/v). High sensitivity and reproducibility were obtained with limits of detection in the range of 0.12-0.25 μg/L (sample volume, 4 mL), and relative standard deviations between 2.9 and 3.4% (10 μg/L, n = 6). Enrichment factors of 34-39 were obtained. Layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disks had an average lifetime of 50 extractions. Analyte recoveries ranged from 93 to 96% for grape juice and nonalcoholic beer samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Mechanochemical synthesis of dodecyl sulfate anion (DS-) intercalated Cu-Al layered double hydroxide

NASA Astrophysics Data System (ADS)

Qu, Jun; He, Xiaoman; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-12-01

Dodecyl sulfate anion (DS-) was successfully intercalated into the gallery space of Cu-Al layered double hydroxides (LDH) by a non-heating mechanochemical route, in which basic cupric carbonate (Cu2(OH)2CO3) and aluminum hydroxide (Al(OH)3) were first dry ground and then agitated in SDS solution under ambient environment. The organics modified Cu-Al LDH showed good adsorption ability toward 2,4-dichlorophenoxyacetic acid (2, 4-D). The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), CHS elemental analysis and Scanning electron microscopy (SEM). The LDH precursor prepared by ball-milling could directly react with SDS molecules forming a pure phase of DS- pillared Cu-Al LDH, which was not observed with the LDH product through the ion-exchange of DS- at room temperature. The process introduced here may be applied to manufacture other types of organic modified composites for pollutants removal and other applications.

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.

The Role of Superthermal Electrons in the Formation of Double Layers and their Application in Space Plasmas

NASA Astrophysics Data System (ADS)

Singh, N.

2014-12-01

It is now widely recognized that superthermal electrons commonly exist with the thermal population in most space plasmas. When plasmas consisting of such electron population expand, double layers (DLs) naturally forma due to charge separation; the more mobile superthermal electrons march ahead of the thermal population, leaving a positive charge behind and generating electric fields. Under certain conditions such fields evolve into thin double layers or shocks. The double layers accelerate ions. Such double-layer formation was first invoked to explain expansion of laser produced plasmas. Since then it has been studied in laboratory experiments, and applied to (i) polar wind acceleration,(ii) the existence of low-altitude double layers in the auroral acceleration, (iii) a possible mechanism for the origination of the solar wind, (iv) the helicon double layer thrusters, and (v) the deceleration of electrons after their acceleration in solar flare events. The role of superthermal-electron driven double layers, also known as the low-altitude auroral double layers in the upward current region, in the upward acceleration of ionospheric ions is well-known. In the auroral application the upward moving superthermal electrons consist of backscattered downgoing primary energetic electrons as well as the secondary electrons. Similarly we suggest that such double layers might play roles in the acceleration of ions in the solar wind across the coronal transition region, where the superthermal electrons are supplied by magnetic reconnection events. We will present a unified theoretical view of the superthermal electron-driven double layers and their applications. We will summarize theoretical, experimental, simulation and observational results highlighting the common threads running through the various existing studies.

Electrodeposition of Polymer Nanostructures using Three Diffuse Double Layers: Polymerization beyond the Liquid/Liquid Interfaces

NASA Astrophysics Data System (ADS)

Divya, Velpula; Sangaranarayanan, M. V.

2018-04-01

Nanostructured conducting polymers have received immense attention during the past few decades on account of their phenomenal usefulness in diverse contexts, while the interface between two immiscible liquids is of great interest in chemical and biological applications. Here we propose a novel Electrode(solid)/Electrolyte(aqueous)/Electrolyte(organic) Interfacial assembly for the synthesis of polymeric nanostructures using a novel concept of three diffuse double layers. There exist remarkable differences between the morphologies of the polymers synthesized using the conventional electrode/electrolyte method and that of the new approach. In contrast to the commonly employed electrodeposition at liquid/liquid interfaces, these polymer modified electrodes can be directly employed in diverse applications such as sensors, supercapacitors etc.

Carbon Redox-Polymer-Gel Hybrid Supercapacitors.

PubMed

Vlad, A; Singh, N; Melinte, S; Gohy, J-F; Ajayan, P M

2016-02-26

Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances.

Molecular dynamics in aluminum layered double hydroxides as studied by 1H T1ρ NMR measurements

NASA Astrophysics Data System (ADS)

Vyalikh, Anastasia; Wang, De-Yi; Wagenknecht, Udo; Heinrich, Gert; Scheler, Ulrich

2011-06-01

Proton dynamics in pristine and organically-modified layered double hydroxide has been studied by 1H T1ρ. Inverse Laplace transform with spectral resolution results in a correlation of T1ρ and chemical shift. In LDH two contributions are resolved. They are assigned to the metal hydroxides, forming the LDH sheets (4-8 ms), and mobile interlayer water (2 ms). Apparent T1ρ values of OH-protons in surfactant-modified LDH are different in dodecylbenzenesulfonate- (SDBS) and sodium octasulfonate- (C8) modified LDH. This difference is explained by the presence of water in LDH-SDBS. The effects of spin diffusion have been studied by performing 2D 1H RFDR in the LDH-SDBS.

A solution blending route to ethylene propylene diene terpolymer/layered double hydroxide nanocomposites

PubMed Central

Acharya, H; Bhowmick, Anil K

2007-01-01

Ethylene propylene diene terpolymer (EPDM)/MgAl layered double hydroxide (LDH) nanocomposites have been synthesized by solution intercalation using organically modified LDH (DS-LDH). The molecular level dispersion of LDH nanolayers has been verified by the disappearance of basal XRD peak of DS-LDH in the composites. The internal structures, of the nanocomposite with the dispersion nature of LDH particles in EPDM matrix have been studied by TEM and AFM. Thermogravimetric analysis (TGA) shows thermal stability of nanocomposites improved by ≈40 °C when 10% weight loss was selected as point of comparison. The degradation for pure EPDM is faster above 380 °C while in case of its nanocomposites, it is much slower.

Organic-aqueous crossover coating process for the desmopressin orally disintegrating microparticles.

PubMed

Kim, Ju-Young; Hwang, Kyu-Mok; Park, Chun-Woong; Rhee, Yun-Seok; Park, Eun-Seok

2015-02-01

The purpose of the present study was to prepare desmopressin orally disintegrating microparticles (ODMs) using organic-aqueous crossover coating process which featured an organic sub-coating followed by an aqueous active coating. Sucrose beads and hydroxypropyl cellulose (HPC) were used as inert cores and a coating material, respectively. Characterizations including size distribution analysis, in-vitro release studies and in-vitro disintegration studies were performed. A pharmacokinetic study of the ODMs was also conducted in eight beagle dogs. It was found that sucrose beads should be coated using organic solvents to preserve their original morphology. For the active coating, the aqueous coating solution should be used for drug stability. When sucrose beads were coated using organic-aqueous crossover coating process, double-layer ODMs with round shapes were produced with detectable impurities below limit of US Pharmacopeia. The median size of ODMs was 195.6 μm, which was considered small enough for a good mouthfeel. The ODMs dissolved in artificial saliva within 15 s because of hydrophilic materials including sucrose and HPC in the ODMs. Because of its fast-dissolving properties, 100% release of the drug was reached within 5 min. Pharmacokinetic parameters including Cmax and AUC24 indicated bioequivalence of the ODMs and the conventional immediate release tablets. Therefore, by using the organic-aqueous crossover coating process, double-layer ODMs were successively prepared with small size, round shapes and good drug stability.

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.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on a 87.6 in diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on an 87.6 in. diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr, respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

A novel porous anionic metal–organic framework with pillared double-layer structure for selective adsorption of dyes

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

Sheng, Shu-Nan; Han, Yi; Wang, Bin

2016-01-15

A novel porous anionic metal–organic framework, (Me{sub 2}NH{sub 2}){sub 2}[Zn{sub 2}L{sub 1.5}bpy]·2DMF (BUT-201; H{sub 4}L=4,8-disulfonaphthalene-2,6-dicarboxylic acid; bpy=4,4-bipyridine; DMF=N,N-dimethylformamide), with pillared double-layer structure has been synthesized through the reaction of a sulfonated carboxylic acid ligand and Zn(NO{sub 3}){sub 2}·6H{sub 2}O with 4,4-bipyridine as a co-ligand. It is found that BUT-201 can rapidly adsorb cationic dyes with a smaller size such as Methylene Blue (MB) and Acriflavine Hydrochloride (AH) by substitution of guest (CH{sub 3}){sub 2}NH{sub 2}{sup +}, but has no adsorption towards the cationic dyes with a lager size such as Methylene Violet (MV), the anionic dyes like C. I. Acidmore » Yellow 1 (AY1) and neutral dyes like C. I. Solvent Yellow 7 (SY7), respectively. The results show that the adsorption behavior of BUT-201 relates not only to the charge but also to the size/shape of dyes. Furthermore, the adsorbed dyes can be gradually released in the methanol solution of LiNO{sub 3}. - Graphical abstract: A porous anionic metal–organic framework (BUT-201) can selectively adsorb the cationic dyes by cationic guest molecule substitution, and the adsorbed dyes can be gradually released in the methanol solution of LiNO{sub 3}. - Highlights: • An anionic metal-organic framework (BUT-201) has been synthesized and characterized. • BUT-201 has a three-dimensional (3D) pillared double-layer structure. • BUT-201 can selectively and rapidly adsorb cationic dyes. • The adsorbed dyes can be gradually released in the methanol solution of LiNO{sub 3}.« less

Organic Field Effect Transistor Using Amorphous Fluoropolymer as Gate Insulating Film

NASA Astrophysics Data System (ADS)

Kitajima, Yosuke; Kojima, Kenzo; Mizutani, Teruyoshi; Ochiai, Shizuyasu

Organic field effect transistors are fabricated by the active layer of Regioregular poly (3-hexylthiophene-2,5-diy)(P3HT) thin film. CYTOP thin film made from Amorphous Fluoropolymer and fabricated by spin-coating is adopted to a gate dielectric layer on Polyethylenenaphthalate (PEN) thin film that is the substrate of an organic field effect transistor. The surface morphology and molecular orientation of P3HT thin films is observed by atomic force microscope (AFM) and X-Ray diffractometer (XRD). Grains are observed on the CYTOP thin film via an AFM image and the P3HT molecule is oriented perpendicularly on the CYTOP thin film. Based on the performance of the organic field effect transistor, the carrier mobility is 0.092 cm2/Vs, the ON/OFF ratio is 7, and the threshold voltage is -12 V. The ON/OFF ratio is relatively low and to improve On/Off ratio, the CYTOP/Polyimide double gate insulating layer is adopted to OFET.

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.

Organic Light-Emitting Diodes with a Perylene Interlayer Between the Electrode-Organic Interface

NASA Astrophysics Data System (ADS)

Saikia, Dhrubajyoti; Sarma, Ranjit

2018-01-01

The performance of an organic light-emitting diode (OLED) with a vacuum-deposited perylene layer over a fluorine-doped tin oxide (FTO) surface is reported. To investigate the effect of the perylene layer on OLED performance, different thicknesses of perylene are deposited on the FTO surface and their current density-voltages (J-V), luminance-voltages (L-V) and device efficiency characteristics at their respective thickness are studied. Further analysis is carried out with an UV-visible light double-beam spectrophotometer unit, a four-probe resistivity unit and a field emission scanning electron microscope set up to study the optical transmittance, sheet resistance and surface morphology of the bilayer anode film. We used N,N'-bis(3-methyl phenyl)- N,N'(phenyl)-benzidine (TPD) as the hole transport layer, Tris(8-hydroxyquinolinato)aluminum (Alq3) as a light-emitting layer and lithium fluoride as an electron injection layer. The luminance efficiency of an OLED structure with a 9-nm-thick perylene interlayer is increased by 2.08 times that of the single-layer FTO anode OLED. The maximum value of current efficiency is found to be 5.25 cd/A.

Effect of gravity modulation on thermosolutal convection in an infinite layer of fluid

NASA Astrophysics Data System (ADS)

Saunders, B. V.; Murray, B. T.; McFadden, G. B.; Coriell, S. R.; Wheeler, A. A.

1991-10-01

The effect of time-periodic vertical gravity modulation on the onset of thermosolutal convection in an infinite horizontal layer with stress free boundaries is studied using Floquet theory for the linear stability analysis. Situations are considered for which the fluid layer is stably stratified in either the fingering or diffusive regimes of double diffusive convection. Results are presented both with and without steady background acceleration. Modulation may stabilize an unstable base solution or destabilize a stable base solution. In addition to synchronous and subharmonic response to the modulation frequency, instability in the double diffusive system can occur via a complex conjugate mode. In the diffusive regime, where oscillatory onset occurs in the unmodulated system, regions of resonant instability occur and exhibit strong coupling with the unmodulated oscillatory frequency.

Structure of large dsDNA viruses

PubMed Central

Klose, Thomas; Rossmann, Michael G.

2015-01-01

Nucleocytoplasmic large dsDNA viruses (NCLDVs) encompass an ever-increasing group of large eukaryotic viruses, infecting a wide variety of organisms. The set of core genes shared by all these viruses includes a major capsid protein with a double jelly-roll fold forming an icosahedral capsid, which surrounds a double layer membrane that contains the viral genome. Furthermore, some of these viruses, such as the members of the Mimiviridae and Phycodnaviridae have a unique vertex that is used during infection to transport DNA into the host. PMID:25003382

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

A Novel Type of Aqueous Dispersible Ultrathin-Layered Double Hydroxide Nanosheets for in Vivo Bioimaging and Drug Delivery.

PubMed

Yan, Li; Zhou, Mengjiao; Zhang, Xiujuan; Huang, Longbiao; Chen, Wei; Roy, Vellaisamy A L; Zhang, Wenjun; Chen, Xianfeng

2017-10-04

Layered double hydroxide (LDH) nanoparticles have been widely used for various biomedical applications. However, because of the difficulty of surface functionalization of LDH nanoparticles, the systemic administration of these nanomaterials for in vivo therapy remains a bottleneck. In this work, we develop a novel type of aqueous dispersible two-dimensional ultrathin LDH nanosheets with a size of about 50 nm and a thickness of about 1.4 to 4 nm. We are able to covalently attach positively charged rhodamine B fluorescent molecules to the nanosheets, and the nanohybrid retains strong fluorescence in liquid and even dry powder form. Therefore, it is available for bioimaging. Beyond this, it is convenient to modify the nanosheets with neutral poly(ethylene glycol) (PEG), so the nanohybrid is suitable for drug delivery through systemic administration. Indeed, in the test of using these nanostructures for delivery of a negatively charged anticancer drug, methotrexate (MTX), in a mouse model, dramatically improved therapeutic efficacy is achieved, indicated by the effective inhibition of tumor growth. Furthermore, our systematic in vivo safety investigation including measuring body weight, determining biodistribution in major organs, hematology analysis, blood biochemical assay, and hematoxylin and eosin stain demonstrates that the new material is biocompatible. Overall, this work represents a major development in the path of modifying functional LDH nanomaterials for clinical applications.

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.

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.

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.

Early Stage Anodic Instability of Glassy Carbon Electrodes in Propylene Carbonate Solvent Containing Lithium Hexafluorophosphate.

PubMed

Carino, Emily V; Newman, Daniel J; Connell, Justin G; Kim, Chaerin; Brushett, Fikile R

2017-10-31

Irreversible changes to the morphology of glassy carbon (GC) electrodes at potentials between 3.5 and 4.5 V vs Li/Li + in propylene carbonate (PC) solvent containing lithium hexafluorophosphate (LiPF 6 ) are reported. Analysis of cyclic voltammetry (CV) experiments in the range of 3.0 to 6.0 V shows that the capacitance of the electrochemical double-layer increased irreversibly beginning at potentials as low as 3.5 V. These changes resulted from nonfaradaic interactions, and were not due to oxidative electrochemical decomposition of the electrode and electrolyte, anion intercalation, nor caused by the presence of water, a common impurity in organic electrolyte solutions. Atomic force microscopy (AFM) images revealed that increasing the potential of a bare GC surface from 3.0 to 4.5 V resulted in a 6× increase in roughness, in good agreement with the changes in double-layer capacitance. Treating the GC surface via exposure to trichloromethylsilane vapors resulted in a stable double-layer capacitance between 3.0 and 4.5 V, and this treatment also correlated with less roughening. These results inform future efforts aimed at controlling surface composition and morphology of carbon electrodes.

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

Carino, Emily V.; Newman, Daniel J.; Connell, Justin G.

In this paper, irreversible changes to the morphology of glassy carbon (GC) electrodes at potentials between 3.5 and 4.5 V vs Li/Li + in propylene carbonate (PC) solvent containing lithium hexafluorophosphate (LiPF 6) are reported. Analysis of cyclic voltammetry (CV) experiments in the range of 3.0 to 6.0 V shows that the capacitance of the electrochemical double -layer increased irreversibly beginning at potentials as low as 3.5 V. These changes resulted from nonfaradaic interactions, and were not due to oxidative electrochemical decomposition of the electrode and electrolyte, anion intercalation, nor caused by the presence of water, a common impurity inmore » organic electrolyte solutions. Atomic force microscopy (AFM) images revealed that increasing the potential of a bare GC surface from 3.0 to 4.5 V resulted in a 6X increase in roughness, in good agreement with the changes in double -layer capacitance. Treating the GC surface via exposure to trichloromethylsilane vapors resulted in a stable double -layer capacitance between 3.0 and 4.5 V, and this treatment also correlated with less roughening. Lastly, these results inform future efforts aimed at controlling surface composition and morphology of carbon electrodes.« less

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.

Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations.

PubMed

Yokota, Yasuyuki; Miyamoto, Hiroo; Imanishi, Akihito; Takeya, Jun; Inagaki, Kouji; Morikawa, Yoshitada; Fukui, Ken-Ichi

2018-05-09

Electric double-layer transistors based on ionic liquid/organic semiconductor interfaces have been extensively studied during the past decade because of their high carrier densities at low operation voltages. Microscopic structures and the dynamics of ionic liquids likely determine the device performance; however, knowledge of these is limited by a lack of appropriate experimental tools. In this study, we investigated ionic liquid/organic semiconductor interfaces using molecular dynamics to reveal the microscopic properties of ionic liquids. The organic semiconductors include pentacene, rubrene, fullerene, and 7,7,8,8-tetracyanoquinodimethane (TCNQ). While ionic liquids close to the substrate always form the specific layered structures, the surface properties of organic semiconductors drastically alter the ionic dynamics. Ionic liquids at the fullerene interface behave as a two-dimensional ionic crystal because of the energy gain derived from the favorable electrostatic interaction on the corrugated periodic substrate.

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.

Bifunctional sensor of pentachlorophenol and copper ions based on nanostructured hybrid films of humic acid and exfoliated layered double hydroxide via a facile layer-by-layer assembly.

PubMed

Yuan, Shuang; Peng, Dinghua; Hu, Xianluo; Gong, Jingming

2013-06-27

A new, highly sensitive bifunctional electrochemical sensor for the simultaneous determination of pentachlorophenol (PCP) and copper ions (Cu(2+)) has been developed, where organic-inorganic hybrid ultrathin films were fabricated by alternate assembly of humic acid (HA) and exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets onto ITO substrates via a layer-by-layer (LBL) approach. The multilayer films were then characterized by means of UV-vis spectrometry, scanning electron microscopy (SEM), and atomic force microscope (AFM). These films were found to have a relatively smooth surface with almost equal amounts of HA incorporated in each cycle. Its electrochemical performance was systematically investigated. Our results demonstrate that such a newly designed (LDH/HA)n multilayer films, combining the individual properties of HA (dual recognition ability for organic herbicides and metal ions) together with LDH nanosheets (a rigid inorganic matrix), can be applied to the simultaneous analysis of PCP and Cu(II) without interference from each other. The LBL assembled nanoarchitectures were further investigated by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR), which provides insight for bifunctional sensing behavior. Under the optimized conditions, the detection limit was found to be as low as 0.4 nM PCP, well below the guideline value of PCP in drinking water (3.7 nM) set by the United States Environmental Protection Agency (U.S. EPA), and 2.0 nM Cu(2+), much below the guideline value (2.0 mg L(-1), ~31.2 nM) from the World Health Organization (WHO), respectively. Toward the goal for practical applications, this simple and cost-effective probe was further evaluated by monitoring PCP and Cu(II) in water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Boosted output performance of triboelectric nanogenerator via electric double layer effect

PubMed Central

Chun, Jinsung; Ye, Byeong Uk; Lee, Jae Won; Choi, Dukhyun; Kang, Chong-Yun; Kim, Sang-Woo; Wang, Zhong Lin; Baik, Jeong Min

2016-01-01

For existing triboelectric nanogenerators (TENGs), it is important to explore unique methods to further enhance the output power under realistic environments to speed up their commercialization. We report here a practical TENG composed of three layers, in which the key layer, an electric double layer, is inserted between a top layer, made of Al/polydimethylsiloxane, and a bottom layer, made of Al. The efficient charge separation in the middle layer, based on Volta's electrophorus, results from sequential contact configuration of the TENG and direct electrical connection of the middle layer to the earth. A sustainable and enhanced output performance of 1.22 mA and 46.8 mW cm−2 under low frequency of 3 Hz is produced, giving over 16-fold enhancement in output power and corresponding to energy conversion efficiency of 22.4%. Finally, a portable power-supplying system, which provides enough d.c. power for charging a smart watch or phone battery, is also successfully developed. PMID:27703165

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.

S-Layer Protein Self-Assembly

PubMed Central

Pum, Dietmar; Toca-Herrera, Jose Luis; Sleytr, Uwe B.

2013-01-01

Crystalline S(urface)-layers are the most commonly observed cell surface structures in prokaryotic organisms (bacteria and archaea). S-layers are highly porous protein meshworks with unit cell sizes in the range of 3 to 30 nm, and thicknesses of ~10 nm. One of the key features of S-layer proteins is their intrinsic capability to form self-assembled mono- or double layers in solution, and at interfaces. Basic research on S-layer proteins laid foundation to make use of the unique self-assembly properties of native and, in particular, genetically functionalized S-layer protein lattices, in a broad range of applications in the life and non-life sciences. This contribution briefly summarizes the knowledge about structure, genetics, chemistry, morphogenesis, and function of S-layer proteins and pays particular attention to the self-assembly in solution, and at differently functionalized solid supports. PMID:23354479

Biomimetic collagen I and IV double layer Langmuir-Schaefer films as microenvironment for human pluripotent stem cell derived retinal pigment epithelial cells.

PubMed

Sorkio, Anni E; Vuorimaa-Laukkanen, Elina P; Hakola, Hanna M; Liang, Huamin; Ujula, Tiina A; Valle-Delgado, Juan José; Österberg, Monika; Yliperttula, Marjo L; Skottman, Heli

2015-05-01

The environmental cues received by the cells from synthetic substrates in vitro are very different from those they receive in vivo. In this study, we applied the Langmuir-Schaefer (LS) deposition, a variant of Langmuir-Blodgett technique, to fabricate a biomimetic microenvironment mimicking the structure and organization of native Bruch's membrane for the production of the functional human embryonic stem cell derived retinal pigment epithelial (hESC-RPE) cells. Surface pressure-area isotherms were measured simultaneously with Brewster angle microscopy to investigate the self-assembly of human collagens type I and IV on air-subphase interface. Furthermore, the structure of the prepared collagen LS films was characterized with scanning electron microscopy, atomic force microscopy, surface plasmon resonance measurements and immunofluorescent staining. The integrity of hESC-RPE on double layer LS films was investigated by measuring transepithelial resistance and permeability of small molecular weight substance. Maturation and functionality of hESC-RPE cells on double layer collagen LS films was further assessed by RPE-specific gene and protein expression, growth factor secretion, and phagocytic activity. Here, we demonstrated that the prepared collagen LS films have layered structure with oriented fibers corresponding to architecture of the uppermost layers of Bruch's membrane and result in increased barrier properties and functionality of hESC-RPE cells as compared to the commonly used dip-coated controls. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbon Redox-Polymer-Gel Hybrid Supercapacitors

PubMed Central

Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P.M.

2016-01-01

Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances. PMID:26917470

Double Dirac point semimetal in 2D material: Ta2Se3

NASA Astrophysics Data System (ADS)

Ma, Yandong; Jing, Yu; Heine, Thomas

2017-06-01

Here, we report by first-principles calculations one new stable 2D Dirac material, Ta2Se3 monolayer. For this system, stable layered bulk phase exists, and exfoliation should be possible. Ta2Se3 monolayer is demonstrated to support two Dirac points close to the Fermi level, achieving the exotic 2D double Dirac semimetal. And like 2D single Dirac and 2D node-line semimetals, spin-orbit coupling could introduce an insulating state in this new class of 2D Dirac semimetals. Moreover, the Dirac feature in this system is layer-dependent and a metal-to-insulator transition is identified in Ta2Se3 when reducing the layer-thickness from bilayer to monolayer. These findings are of fundamental interests and of great importance for nanoscale device applications.

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.

ZnS-Sb2S3@C Core-Double Shell Polyhedron Structure Derived from Metal-Organic Framework as Anodes for High Performance Sodium Ion Batteries.

PubMed

Dong, Shihua; Li, Caixia; Ge, Xiaoli; Li, Zhaoqiang; Miao, Xianguang; Yin, Longwei

2017-06-27

Taking advantage of zeolitic imidazolate framework (ZIF-8), ZnS-Sb 2 S 3 @C core-double shell polyhedron structure is synthesized through a sulfurization reaction between Zn 2+ dissociated from ZIF-8 and S 2- from thioacetamide (TAA), and subsequently a metal cation exchange process between Zn 2+ and Sb 3+ , in which carbon layer is introduced from polymeric resorcinol-formaldehyde to prevent the collapse of the polyhedron. The polyhedron composite with a ZnS inner-core and Sb 2 S 3 /C double-shell as anode for sodium ion batteries (SIBs) shows us a significantly improved electrochemical performance with stable cycle stability, high Coulombic efficiency and specific capacity. Peculiarly, introducing a carbon shell not only acts as an important protective layer to form a rigid construction and accommodate the volume changes, but also improves the electronic conductivity to optimize the stable cycle performance and the excellent rate property. The architecture composed of ZnS inner core and a complex Sb 2 S 3 /C shell not only facilitates the facile electrolyte infiltration to reduce the Na-ion diffusion length to improve the electrochemical reaction kinetics, but also prevents the structure pulverization caused by Na-ion insertion/extraction. This approach to prepare metal sulfides based on MOFs can be further extended to design other nanostructured systems for high performance energy storage devices.

From nicotinate-containing layered double hydroxides (LDHs) to NAD coenzyme-LDH nanocomposites - Syntheses and structural characterization by various spectroscopic methods

NASA Astrophysics Data System (ADS)

Muráth, Szabolcs; Dudás, Csilla; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

2017-07-01

The syntheses of nicotinate anion- and NAD coenzyme-layered double hydroxide (LDH) composites were performed with the aim of having the organic component among the layers. In-house prepared CaAl-LDHs were the host materials. Intercalation was attempted by direct ion exchange or by the dehydration-rehydration method applying aqueous solvent mixtures (containing ethanol, propanol, acetone, N,N-dimethylformamide). For structural characterization, beside X-ray diffractometry, X-ray photoelectron and IR spectroscopies, transmission and scanning electron microscopies as well as energy-dispersive X-ray analysis were used. Molecular modelling served for the visualization of the arrangements of the intercalated ions among the layers of the LDH samples. Although not all the intercalation methods and solvent mixtures led to intercalated composite materials, successful ones could be identified. The combination of spectroscopic methods helped in proposing sensible spatial arrangements for the intercalated anions. The NAD-CaAl-LDH composite proved to be an active catalyst in the oxidation of hydroquinone to 1,4-bezoquinoe in the presence of H2O2.

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.

Fast valve based on double-layer eddy-current repulsion for disruption mitigation in Experimental Advanced Superconducting Tokamak.

PubMed

Zhuang, H D; Zhang, X D

2015-05-01

A fast valve based on the double-layer eddy-current repulsion mechanism has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to a double-layer eddy-current coil, a preload system was added to improve the security of the valve, whereby the valve opens more quickly and the open-valve time becomes shorter, making it much safer than before. In this contribution, testing platforms, open-valve characteristics, and throughput of the fast valve are discussed. Tests revealed that by choosing appropriate parameters the valve opened within 0.15 ms, and open-valve times were no longer than 2 ms. By adjusting working parameter values, the maximum number of particles injected during this open-valve time was estimated at 7 × 10(22). The fast valve will become a useful tool to further explore disruption mitigation experiments on EAST in 2015.

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.

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.

Measurements of electrostatic double layer potentials with atomic force microscopy

NASA Astrophysics Data System (ADS)

Giamberardino, Jason

The aim of this thesis is to provide a thorough description of the development of theory and experiment pertaining to the electrostatic double layer (EDL) in aqueous electrolytic systems. The EDL is an important physical element of many systems and its behavior has been of interest to scientists for many decades. Because many areas of science and engineering move to test, build, and understand systems at smaller and smaller scales, this work focuses on nanoscopic experimental investigations of the EDL. In that vein, atomic force microscopy (AFM) will be introduced and discussed as a tool for making high spatial resolution measurements of the solid-liquid interface, culminating in a description of the development of a method for completely characterizing the EDL. This thesis first explores, in a semi-historical fashion, the development of the various models and theories that are used to describe the electrostatic double layer. Later, various experimental techniques and ideas are addressed as ways to make measurements of interesting characteristics of the EDL. Finally, a newly developed approach to measuring the EDL system with AFM is introduced. This approach relies on both implementation of existing theoretical models with slight modifications as well as a unique experimental measurement scheme. The model proposed clears up previous ambiguities in definitions of various parameters pertaining to measurements of the EDL and also can be used to fully characterize the system in a way not yet demonstrated.

[Organic carbon and carbon mineralization characteristics in nature forestry soil].

PubMed

Yang, Tian; Dai, Wei; An, Xiao-Juan; Pang, Huan; Zou, Jian-Mei; Zhang, Rui

2014-03-01

Through field investigation and indoor analysis, the organic carbon content and organic carbon mineralization characteristics of six kinds of natural forest soil were studied, including the pine forests, evergreen broad-leaved forest, deciduous broad-leaved forest, mixed needle leaf and Korean pine and Chinese pine forest. The results showed that the organic carbon content in the forest soil showed trends of gradual decrease with the increase of soil depth; Double exponential equation fitted well with the organic carbon mineralization process in natural forest soil, accurately reflecting the mineralization reaction characteristics of the natural forest soil. Natural forest soil in each layer had the same mineralization reaction trend, but different intensity. Among them, the reaction intensity in the 0-10 cm soil of the Korean pine forest was the highest, and the intensities of mineralization reaction in its lower layers were also significantly higher than those in the same layers of other natural forest soil; comparison of soil mineralization characteristics of the deciduous broad-leaved forest and coniferous and broad-leaved mixed forest found that the differences of litter species had a relatively strong impact on the active organic carbon content in soil, leading to different characteristics of mineralization reaction.

FIBER AND INTEGRATED OPTICS: Bandgap modes in a coupled waveguide array

NASA Astrophysics Data System (ADS)

Usievich, B. A.; Nurligareev, D. Kh; Svetikov, V. V.; Sychugov, V. A.

2009-08-01

This work examines a waveguide array that consists of ten Nb2O5/SiO2 double layers and supports a 0.63-μm surface wave. The deposition of a Nb2O5 capping layer on top of the waveguide array enables a marked increase in the wave field intensity on its surface. The efficiency of surface-wave excitation in the Kretschmann configuration can be optimised by adjusting the number of double layers. We analyse the behaviour of the Bragg mode in relation to the thickness of the layer exposed to air and the transition of this mode from the second allowed band to the first through the bandgap of the system. In addition, the conventional leaky mode converts to a surface mode and then to a guided mode.

Green Rust: Its Electrochemical Generation, Characterization, and Implications

DTIC Science & Technology

2009-02-01

FeOOH), and lepidocrocite ( γ -FeOOH) in well-aerated systems, and hematite (α- Fe2O3 ) maghemite (δ- Fe2O3 ) or magnetite (Fe3O4) in oxygen-depleted...ferric hydroxides that belong to a family of minerals known as layered double hydroxides ( LDH ). Its general formula is [FeII(6-x) FeIIIx (OH)12]x+[Ax...of ferrous and ferric hydroxides that belong to a family of minerals known as layered double hydroxides ( LDH ). Its general formula is [FeII (6-x) FeIII

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.

Energize Electrochemical Double Layer Capacitor by Introducing an Ambipolar Organic Redox Radical in Electrolyte.

PubMed

Wang, Yonggang; Hu, Lintong; Zhang, Yue; Shi, Chao; Guo, Kai; Zhai, Tianyou; Li, Huiqiao

2018-05-24

Carbon based electrochemical double layer capacitors (EDLCs) generally exhibit high power and long life, but low energy density/capacitance. Pore/morphology optimization and pseudocapacitive materials modification of carbon materials have been used to improve electrode capacitance, but leading to the consumption of tap density, conductivity and stability. Introducing soluble redox mediators into electrolyte is a promising alternative to improve the capacitance of electrode. However, it is difficult to find one redox mediator that can provide additional capacitance for both positive and negative electrodes simultaneously. Here, an ambipolar organic radical, 2, 2, 6, 6-tetramethylpiperidinyloxyl (TEMPO) is first introduced to the electrolyte, which can substantially contribute additional pseudocapacitance by oxidation at the positive electrode and reduction at the negative electrode simultaneously. The EDLC with TEMPO mediator delivers an energy density as high as 51 Wh kg-1, 2.4 times of the capacitor without TEMPO, and a long cycle stability over 4000 cycles. The achieved results potentially point a new way to improve the energy density of EDLCs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

True Low-Power Self-Locking Soft Actuators.

PubMed

Kim, Seung Jae; Kim, Onnuri; Park, Moon Jeong

2018-03-01

Natural double-layered structures observed in living organisms are known to exhibit asymmetric volume changes with environmental triggers. Typical examples are natural roots of plants, which show unique self-organized bending behavior in response to environmental stimuli. Herein, light- and electro-active polymer (LEAP) based actuators with a double-layered structure are reported. The LEAP actuators exhibit an improvement of 250% in displacement and hold an object three times heavier as compared to that in the case of conventional electro-active polymer actuators. Most interestingly, the bending motion of the LEAP actuators can be effectively locked for a few tens of minutes even in the absence of a power supply. Further, the self-locking LEAP actuators show a large and reversible bending strain of more than 2.0% and require only 6.2 mW h cm -2 of energy to hold an object for 15 min at an operating voltage of 3 V. These novel self-locking soft actuators should find wide applicability in artificial muscles, biomedical microdevices, and various innovative soft robot technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

STM/STS Study of the Sb (111) Surface

NASA Astrophysics Data System (ADS)

Chekmazov, S. V.; Bozhko, S. I.; Smirnov, A. A.; Ionov, A. M.; Kapustin, A. A.

An Sb crystal is a Peierls insulator. Formation of double layers in the Sb structure is due to the shift of atomic planes (111) next but one along the C3 axis. Atomic layers inside the double layer are connected by covalent bonds. The interaction between double layers is determined mainly by Van der Waals forces. The cleave of an Sb single crystal used to be via break of Van der Waals bonds. However, using scanning tunneling microscopy (STM) and spectroscopy (STS) we demonstrated that apart from islands equal in thickness to the double layer, steps of one atomic layer in height also exist on the cleaved Sb (111) surface. Formation of "unpaired" (111) planes on the surface leads to a local break of conditions of Peierls transition. STS experiment reveals higher local density of states (LDOS) measured for "unpaired" (111) planes in comparison with those for the double layer.

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.

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

Nishi, Shohei; Taguchi, Dai; Manaka, Takaaki

By using electric-field-induced optical second-harmonic generation measurement coupled with the conventional current-voltage (I-V) measurement, we studied the carrier transport of organic double-layer diodes with a Au/pentacene/fluorine polymer (FP)/indium zinc oxide (IZO) structure. The rectifying I-V characteristics were converted into the I-E characteristics of the FP and pentacene layers. Results suggest a model in which Schottky-type electron injection from the IZO electrode to the FP layer governs the forward electrical conduction (V > 0), where the space charge electric field produced in the FP layer by accumulated holes at the pentacene/FP interface makes a significant contribution. On the other hand, Schottky-type injection bymore » accumulated interface electrons from the pentacene layer to the FP layer governs the backward electrical conduction (V < 0). The electroluminescence generated from the pentacene layer in the region V > 0 verifies the electron transport across the FP layer, and supports the above suggested model.« less

N-doped structures and surface functional groups of reduced graphene oxide and their effect on the electrochemical performance of supercapacitor with organic electrolyte

NASA Astrophysics Data System (ADS)

Li, Shin-Ming; Yang, Shin-Yi; Wang, Yu-Sheng; Tsai, Hsiu-Ping; Tien, Hsi-Wen; Hsiao, Sheng-Tsung; Liao, Wei-Hao; Chang, Chien-Liang; Ma, Chen-Chi M.; Hu, Chi-Chang

2015-03-01

Nitrogen-doped reduced graphene oxide (N-rGO) has been synthesized using a simple, efficient method combining instant thermal exfoliation and covalent bond transformation from a melamine-graphene oxide mixture. The capacitive performance of N-rGO has been tested in both aqueous (0.5 M H2SO4) and organic (1 M tetraethyl-ammonium tetrafluoroborate (TEABF4) in propylene carbonate (PC)) electrolytes, which are compared with those obtained from thermal-reduced graphene oxide (T-rGO) and chemical-reduced graphene oxide (C-rGO). The contributions of scan-rate-independent (double-layer-like) and scan-rate-dependent (pseudo-capacitance-like) capacitance of all reduced graphene oxides in both aqueous and organic electrolytes were evaluated and compared. The results show that relatively rich oxygen-containing functional groups on C-rGO form significant ion-diffusion barrier, resulting in worse electrochemical responses in organic electrolyte. By contrast, the N-doped structures, large surface area, and lower density of oxygen-containing groups make N-rGO become a promising electrode material for organic electric double-layer capacitors (EDLCs). The capacitance rate-retention of N-rGO reaches 71.1% in 1 M TEABF4/PC electrolyte when the scan rate is elevated to 200 mVs-1, demonstrating that N-rGO improves the relatively low-power drawback of EDLCs in organic electrolytes. The specific energy and power of a symmetric N-rGO cell in the organic electrolyte reach 25 Wh kg-1 and 10 kW kg-1, respectively.

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.

Wireless Power Transmission to Organic Light Emitting Diode Lighting Panel with Magnetically Coupled Resonator

NASA Astrophysics Data System (ADS)

Kim, Yong-Hae; Han, Jun-Han; Kang, Seung-Youl; Cheon, Sanghoon; Lee, Myung-Lae; Ahn, Seong-Deok; Zyung, Taehyoung; Lee, Jeong-Ik; Moon, Jaehyun; Chu, Hye Yong

2012-09-01

We are successful to lit the organic light emitting diode (OLED) lighting panel through the magnetically coupled wireless power transmission technology. For the wireless power transmission, we used the operation frequency 932 kHz, specially designed double spiral type transmitter, small and thin receiver on the four layered printed circuit board, and schottky diodes for the full bridge rectifier. Our white OLED is a hybrid type, in which phosphorescent and fluorescent organics are used together to generate stable white color. The total efficiency of power transmission is around 72%.

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.

Determination of haloacetic acids in water using layered double hydroxides as a sorbent in dispersive solid-phase extraction followed by liquid chromatography with tandem mass spectrometry.

PubMed

Alsharaa, Abdulnaser; Sajid, Muhammad; Basheer, Chanbasha; Alhooshani, Khalid; Lee, Hian Kee

2016-09-01

In the present study, highly efficient and simple dispersive solid-phase extraction procedure for the determination of haloacetic acids in water samples has been established. Three different types of layered double hydroxides were synthesized and used as a sorbent in dispersive solid-phase extraction. Due to the interesting behavior of layered double hydroxides in an acidic medium (pH˂4), the analyte elution step was not needed; the layered double hydroxides are simply dissolved in acid immediately after extraction to release the analytes which are then directly introduced into a liquid chromatography with tandem mass spectrometry system for analysis. Several dispersive solid-phase extraction parameters were optimized to increase the extraction efficiency of haloacetic acids such as temperature, extraction time and pH. Under optimum conditions, good linearity was achieved over the concentration range of 0.05-100 μg/L with detection limits in the range of 0.006-0.05 μg/L. The relative standard deviations were 0.33-3.64% (n = 6). The proposed method was applied to different water samples collected from a drinking water plant to determine the concentrations of haloacetic acids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Time-dependent electrophoresis of a dielectric spherical particle embedded in Brinkman medium

NASA Astrophysics Data System (ADS)

Saad, E. I.; Faltas, M. S.

2018-04-01

An expression for electrophoretic apparent velocity slip in the time-dependent flow of an electrolyte solution saturated in a charged porous medium within an electric double layer adjacent to a dielectric plate under the influence of a tangential uniform electric field is derived. The velocity slip is used as a boundary condition to solve the electrophoretic motion of an impermeable dielectric spherical particle embedded in an electrolyte solution saturated in porous medium under the unsteady Darcy-Brinkman model. Throughout the system, a uniform electric field is applied and maintains with constant strength. Two cases are considered, when the electric double layer enclosing the particle is thin, but finite and when of a particle with a thick double layer. Expressions for the electrophoretic mobility of the particle as functions of the relevant parameters are found. Our results indicate that the time scale for the growth of mobility is significant and small for high permeability. Generally, the effect of the relaxation time for starting electrophoresis is negligible, irrespective of the thickness of the double layer and permeability of the medium. The effects of the elapsed time, permeability, mass density and Debye length parameters on the fluid velocity, the electrophoretic mobility and the acceleration are shown graphically.

Numerical analysis of finite Debye-length effects in induced-charge electro-osmosis.

PubMed

Gregersen, Misha Marie; Andersen, Mathias Baekbo; Soni, Gaurav; Meinhart, Carl; Bruus, Henrik

2009-06-01

For a microchamber filled with a binary electrolyte and containing a flat unbiased center electrode at one wall, we employ three numerical models to study the strength of the resulting induced-charge electro-osmotic (ICEO) flow rolls: (i) a full nonlinear continuum model resolving the double layer, (ii) a linear slip-velocity model not resolving the double layer and without tangential charge transport inside this layer, and (iii) a nonlinear slip-velocity model extending the linear model by including the tangential charge transport inside the double layer. We show that, compared to the full model, the slip-velocity models significantly overestimate the ICEO flow. This provides a partial explanation of the quantitative discrepancy between observed and calculated ICEO velocities reported in the literature. The discrepancy increases significantly for increasing Debye length relative to the electrode size, i.e., for nanofluidic systems. However, even for electrode dimensions in the micrometer range, the discrepancies in velocity due to the finite Debye length can be more than 10% for an electrode of zero height and more than 100% for electrode heights comparable to the Debye length.

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.

The Effect of Rotation on Oscillatory Double-diffusive Convection (Semiconvection)

NASA Astrophysics Data System (ADS)

Moll, Ryan; Garaud, Pascale

2017-01-01

Oscillatory double-diffusive convection (ODDC, more traditionally called semiconvection) is a form of linear double-diffusive instability that occurs in fluids that are unstably stratified in temperature (Schwarzschild unstable), but stably stratified in chemical composition (Ledoux stable). This scenario is thought to be quite common in the interiors of stars and giant planets, and understanding the transport of heat and chemical species by ODDC is of great importance to stellar and planetary evolution models. Fluids unstable to ODDC have a tendency to form convective thermocompositional layers that significantly enhance the fluxes of temperature and chemical composition compared with microscopic diffusion. Although a number of recent studies have focused on studying properties of both layered and nonlayered ODDC, few have addressed how additional physical processes such as global rotation affect its dynamics. In this work, we study first how rotation affects the linear stability properties of rotating ODDC. Using direct numerical simulations, we then analyze the effect of rotation on properties of layered and nonlayered ODDC, and we study how the angle of the rotation axis with respect to the direction of gravity affects layering. We find that rotating systems can be broadly grouped into two categories based on the strength of rotation. The qualitative behavior in the more weakly rotating group is similar to nonrotating ODDC, but strongly rotating systems become dominated by vortices that are invariant in the direction of the rotation vector and strongly influence transport. We find that whenever layers form, rotation always acts to reduce thermal and compositional transport.

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.

Characteristic Features of Double Layers in Rotating, Magnetized Plasma Contaminated with Dust Grains with Varying Charges

NASA Astrophysics Data System (ADS)

Paul, Jaydeep; Nag, Apratim; Devi, Karabi; Das, Himadri Sekhar

2018-03-01

The evolution and the characteristic features of double layers in a plasma under slow rotation and contaminated with dust grains with varying charges under the effect of an external magnetic field are studied. The Coriolis force resulting from the slow rotation is responsible for the generation of an equivalent magnetic field. A comparatively new pseudopotential approach has been used to derive the small amplitude double layers. The effect of the relative electron-ion concentration, as well as the temperature ratio, on the formation of the double layers has also been investigated. The study reveals that compressive, as well as rarefactive, double layers can be made to co-exist in plasma by controlling the dust charge fluctuation effect supplemented by variations of the plasma constituents. The effectiveness of slow rotation in causing double layers to exist has also emanated from the study. The results obtained could be of interest because of their possible applications in both laboratories and space.

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.

Plasmon modes in monolayer and double-layer black phosphorus under applied uniaxial strain

NASA Astrophysics Data System (ADS)

Saberi-Pouya, S.; Vazifehshenas, T.; Saleh, M.; Farmanbar, M.; Salavati-fard, T.

2018-05-01

We study the effects of an applied in-plane uniaxial strain on the plasmon dispersions of monolayer, bilayer, and double-layer black phosphorus structures in the long-wavelength limit within the linear elasticity theory. In the low-energy limit, these effects can be modeled through the change in the curvature of the anisotropic energy band along the armchair and zigzag directions. We derive analytical relations of the plasmon modes under uniaxial strain and show that the direction of the applied strain is important. Moreover, we observe that along the armchair direction, the changes of the plasmon dispersion with strain are different and larger than those along the zigzag direction. Using the analytical relations of two-layer phosphorene systems, we found that the strain-dependent orientation factor of layers could be considered as a means to control the variations of the plasmon energy. Furthermore, our study shows that the plasmonic collective modes are more affected when the strain is applied equally to the layers compared to the case in which the strain is applied asymmetrically to the layers. We also calculate the effect of strain on the drag resistivity in a double-layer black phosphorus structure and obtain that the changes in the plasmonic excitations, due to an applied strain, are mainly responsible for the predicted results. This study can be readily extended to other anisotropic two-dimensional materials.

Energy Level Alignment of N-Doping Fullerenes and Fullerene Derivatives Using Air-Stable Dopant.

PubMed

Bao, Qinye; Liu, Xianjie; Braun, Slawomir; Li, Yanqing; Tang, Jianxin; Duan, Chungang; Fahlman, Mats

2017-10-11

Doping has been proved to be one of the powerful technologies to achieve significant improvement in the performance of organic electronic devices. Herein, we systematically map out the interface properties of solution-processed air-stable n-type (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl) doping fullerenes and fullerene derivatives and establish a universal energy level alignment scheme for this class of n-doped system. At low doping levels at which the charge-transfer doping induces mainly bound charges, the energy level alignment of the n-doping organic semiconductor can be described by combining integer charger transfer-induced shifts with a so-called double-dipole step. At high doping levels, significant densities of free charges are generated and the charge flows between the organic film and the conducting electrodes equilibrating the Fermi level in a classic "depletion layer" scheme. Moreover, we demonstrate that the model holds for both n- and p-doping of π-backbone molecules and polymers. With the results, we provide wide guidance for identifying the application of the current organic n-type doping technology in organic electronics.

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.

Solar system applications of Mie theory and of radiative transfer of polarized light

NASA Technical Reports Server (NTRS)

Whitehill, L. P.

1972-01-01

A theory of the multiple scattering of polarized light is discussed using the doubling method of van de Hulst. The concept of the Stokes parameters is derived and used to develop the form of the scattering phase matrix of a single particle. The diffuse reflection and transmission matrices of a single scattering plane parallel atmosphere are expressed as a function of the phase matrix, and the symmetry properties of these matrices are examined. Four matrices are required to describe scattering and transmission. The scattering matrix that results from the addition of two identical layers is derived. Using the doubling method, the scattering and transmission matrices of layers of arbitrary optical thickness can be derived. The doubling equations are then rewritten in terms of their Fourier components. Computation time is reduced since each Fourier component doubles independently. Computation time is also reduced through the use of symmetry properties.

A green approach to the synthesis of novel ``Desert rose stone''-like nanobiocatalytic system with excellent enzyme activity and stability

NASA Astrophysics Data System (ADS)

Wang, Min; Bao, Wen-Jing; Wang, Jiong; Wang, Kang; Xu, Jing-Juan; Chen, Hong-Yuan; Xia, Xing-Hua

2014-10-01

3D hierarchical layer double hydroxides (LDHs) have attracted extensive interest due to their unique electronic and catalytic properties. Unfortunately, the existing preparation methods require high temperature or toxic organic compounds, which limits the applications of the 3D hierarchical LDHs in biocatalysis and biomedicine. Herein, we present a green strategy to synthesize ``Desert Rose Stone''-like Mg-Al-CO3 LDH nanoflowers in situ deposited on aluminum substrates via a coprecipitation method using atmospheric carbon dioxide. Using this method, we construct a novel ``Desert Rose Stone''-like nanobiocatalytic system by using HRP as the model enzyme. Compared with the free HRP, the HRP/Mg-Al-LDH nanobiocatalytic system exhibits higher catalytic activity and stability. A smaller apparent Michaelis-Menten constant (0.16 mM) of this system suggests that the encapsulated HRP shows higher affinity towards H2O2.

Lightweight Thermal Insulation for a Liquid-Oxygen Tank

NASA Technical Reports Server (NTRS)

Willen, G. Scott; Lock, Jennifer; Nieczkoski, Steve

2005-01-01

A proposed lightweight, reusable thermal-insulation blanket has been designed for application to a tank containing liquid oxygen, in place of a non-reusable spray-on insulating foam. The blanket would be of the multilayer-insulation (MLI) type and equipped with a pressure-regulated nitrogen purge system. The blanket would contain 16 layers in two 8-layer sub-blankets. Double-aluminized polyimide 0.3 mil (.0.008 mm) thick was selected as a reflective shield material because of its compatibility with oxygen and its ability to withstand ionizing radiation and high temperature. The inner and outer sub-blanket layers, 1 mil (approximately equals 0.025 mm) and 3 mils (approximately equals 0.076 mm) thick, respectively, would be made of the double-aluminized polyimide reinforced with aramid. The inner and outer layers would provide structural support for the more fragile layers between them and would bear the insulation-to-tank attachment loads. The layers would be spaced apart by lightweight, low-thermal-conductance netting made from polyethylene terephthalate.

Early Stage Anodic Instability of Glassy Carbon Electrodes in Propylene Carbonate Solvent Containing Lithium Hexafluorophosphate

DOE PAGES

Carino, Emily V.; Newman, Daniel J.; Connell, Justin G.; ...

2017-09-19

In this paper, irreversible changes to the morphology of glassy carbon (GC) electrodes at potentials between 3.5 and 4.5 V vs Li/Li + in propylene carbonate (PC) solvent containing lithium hexafluorophosphate (LiPF 6) are reported. Analysis of cyclic voltammetry (CV) experiments in the range of 3.0 to 6.0 V shows that the capacitance of the electrochemical double -layer increased irreversibly beginning at potentials as low as 3.5 V. These changes resulted from nonfaradaic interactions, and were not due to oxidative electrochemical decomposition of the electrode and electrolyte, anion intercalation, nor caused by the presence of water, a common impurity inmore » organic electrolyte solutions. Atomic force microscopy (AFM) images revealed that increasing the potential of a bare GC surface from 3.0 to 4.5 V resulted in a 6X increase in roughness, in good agreement with the changes in double -layer capacitance. Treating the GC surface via exposure to trichloromethylsilane vapors resulted in a stable double -layer capacitance between 3.0 and 4.5 V, and this treatment also correlated with less roughening. Lastly, these results inform future efforts aimed at controlling surface composition and morphology of carbon electrodes.« less

Robust sliding mode control applied to double Inverted pendulum system

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

Mahjoub, Sonia; Derbel, Nabil; Mnif, Faical

A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.

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

A two-dimensional DNA lattice implanted polymer solar cell.

PubMed

Lee, Keun Woo; Kim, Kyung Min; Lee, Junwye; Amin, Rashid; Kim, Byeonghoon; Park, Sung Kye; Lee, Seok Kiu; Park, Sung Ha; Kim, Hyun Jae

2011-09-16

A double crossover tile based artificial two-dimensional (2D) DNA lattice was fabricated and the dry-wet method was introduced to recover an original DNA lattice structure in order to deposit DNA lattices safely on the organic layer without damaging the layer. The DNA lattice was then employed as an electron blocking layer in a polymer solar cell causing an increase of about 10% up to 160% in the power conversion efficiency. Consequently, the resulting solar cell which had an artificial 2D DNA blocking layer showed a significant enhancement in power conversion efficiency compared to conventional polymer solar cells. It should be clear that the artificial DNA nanostructure holds unique physical properties that are extremely attractive for various energy-related and photonic applications.

Increased upstream ionization due to formation of a double layer.

PubMed

Thakur, S Chakraborty; Harvey, Z; Biloiu, I A; Hansen, A; Hardin, R A; Przybysz, W S; Scime, E E

2009-01-23

We report observations that confirm a theoretical prediction that formation of a current-free double layer in a plasma expanding into a chamber of larger diameter is accompanied by an increase in ionization upstream of the double layer. The theoretical model argues that the increased ionization is needed to balance the difference in diffusive losses upstream and downstream of the expansion region. In our expanding helicon source experiments, we find that the upstream plasma density increases sharply at the same antenna frequency at which the double layer appears.

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.

Water-Gated n-Type Organic Field-Effect Transistors for Complementary Integrated Circuits Operating in an Aqueous Environment.

PubMed

Porrazzo, Rossella; Luzio, Alessandro; Bellani, Sebastiano; Bonacchini, Giorgio Ernesto; Noh, Yong-Young; Kim, Yun-Hi; Lanzani, Guglielmo; Antognazza, Maria Rosa; Caironi, Mario

2017-01-31

The first demonstration of an n-type water-gated organic field-effect transistor (WGOFET) is here reported, along with simple water-gated complementary integrated circuits, in the form of inverting logic gates. For the n-type WGOFET active layer, high-electron-affinity organic semiconductors, including naphthalene diimide co-polymers and a soluble fullerene derivative, have been compared, with the latter enabling a high electric double layer capacitance in the range of 1 μF cm -2 in full accumulation and a mobility-capacitance product of 7 × 10 -3 μF/V s. Short-term stability measurements indicate promising cycling robustness, despite operating the device in an environment typically considered harsh, especially for electron-transporting organic molecules. This work paves the way toward advanced circuitry design for signal conditioning and actuation in an aqueous environment and opens new perspectives in the implementation of active bio-organic interfaces for biosensing and neuromodulation.

Water-Gated n-Type Organic Field-Effect Transistors for Complementary Integrated Circuits Operating in an Aqueous Environment

PubMed Central

2017-01-01

The first demonstration of an n-type water-gated organic field-effect transistor (WGOFET) is here reported, along with simple water-gated complementary integrated circuits, in the form of inverting logic gates. For the n-type WGOFET active layer, high-electron-affinity organic semiconductors, including naphthalene diimide co-polymers and a soluble fullerene derivative, have been compared, with the latter enabling a high electric double layer capacitance in the range of 1 μF cm–2 in full accumulation and a mobility–capacitance product of 7 × 10–3 μF/V s. Short-term stability measurements indicate promising cycling robustness, despite operating the device in an environment typically considered harsh, especially for electron-transporting organic molecules. This work paves the way toward advanced circuitry design for signal conditioning and actuation in an aqueous environment and opens new perspectives in the implementation of active bio-organic interfaces for biosensing and neuromodulation. PMID:28180187

Organ fusion and defective cuticle function in a lacs1 lacs2 double mutant of Arabidopsis

USDA-ARS?s Scientific Manuscript database

As the outermost layer on aerial tissues of the primary plant body, the cuticle plays important roles in plant development and physiology. The major components of the cuticle are cutin and cuticular wax, both of which are composed primarily of fatty acid derivatives synthesized in the epidermal cell...

New generation of wearable goniometers for motion capture systems

PubMed Central

2014-01-01

Background Monitoring joint angles through wearable systems enables human posture and gesture to be reconstructed as a support for physical rehabilitation both in clinics and at the patient’s home. A new generation of wearable goniometers based on knitted piezoresistive fabric (KPF) technology is presented. Methods KPF single-and double-layer devices were designed and characterized under stretching and bending to work as strain sensors and goniometers. The theoretical working principle and the derived electromechanical model, previously proved for carbon elastomer sensors, were generalized to KPF. The devices were used to correlate angles and piezoresistive fabric behaviour, to highlight the differences in terms of performance between the single layer and the double layer sensors. A fast calibration procedure is also proposed. Results The proposed device was tested both in static and dynamic conditions in comparison with standard electrogoniometers and inertial measurement units respectively. KPF goniometer capabilities in angle detection were experimentally proved and a discussion of the device measurement errors of is provided. The paper concludes with an analysis of sensor accuracy and hysteresis reduction in particular configurations. Conclusions Double layer KPF goniometers showed a promising performance in terms of angle measurements both in quasi-static and dynamic working mode for velocities typical of human movement. A further approach consisting of a combination of multiple sensors to increase accuracy via sensor fusion technique has been presented. PMID:24725669

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.

System for rapid biohydrogen phenotypic screening of microorganisms using a chemochromic sensor

DOEpatents

Seibert, Michael; Benson, David K.; Flynn, Timothy Michael

2002-01-01

Provided is a system for identifying a hydrogen gas producing organism. The system includes a sensor film having a first layer comprising a transition metal oxide or oxysalt and a second layer comprising a hydrogen-dissociative catalyst metal, the first and second layers having an inner and an outer surface wherein the inner surface of the second layer is deposited on the outer surface of the first layer, and a substrate adjacent to the outer surface of the second layer, the organism isolated on the substrate.

Doubled heterogeneous crystal nucleation in sediments of hard sphere binary-mass mixtures

NASA Astrophysics Data System (ADS)

Löwen, Hartmut; Allahyarov, Elshad

2011-10-01

Crystallization during the sedimentation process of a binary colloidal hard spheres mixture is explored by Brownian dynamics computer simulations. The two species are different in buoyant mass but have the same interaction diameter. Starting from a completely mixed system in a finite container, gravity is suddenly turned on, and the crystallization process in the sample is monitored. If the Peclet numbers of the two species are both not too large, crystalline layers are formed at the bottom of the cell. The composition of lighter particles in the sedimented crystal is non-monotonic in the altitude: it is first increasing, then decreasing, and then increasing again. If one Peclet number is large and the other is small, we observe the occurrence of a doubled heterogeneous crystal nucleation process. First, crystalline layers are formed at the bottom container wall which are separated from an amorphous sediment. At the amorphous-fluid interface, a secondary crystal nucleation of layers is identified. This doubled heterogeneous nucleation can be verified in real-space experiments on colloidal mixtures.

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

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.

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.

Self-consistent electrostatic simulations of reforming double layers in the downward current region of the aurora

NASA Astrophysics Data System (ADS)

Gunell, H.; Andersson, L.; De Keyser, J.; Mann, I.

2015-10-01

The plasma on a magnetic field line in the downward current region of the aurora is simulated using a Vlasov model. It is found that an electric field parallel to the magnetic fields is supported by a double layer moving toward higher altitude. The double layer accelerates electrons upward, and these electrons give rise to plasma waves and electron phase-space holes through beam-plasma interaction. The double layer is disrupted when reaching altitudes of 1-2 Earth radii where the Langmuir condition no longer can be satisfied due to the diminishing density of electrons coming up from the ionosphere. During the disruption the potential drop is in part carried by the electron holes. The disruption creates favourable conditions for double layer formation near the ionosphere and double layers form anew in that region. The process repeats itself with a period of approximately 1 min. This period is determined by how far the double layer can reach before being disrupted: a higher disruption altitude corresponds to a longer repetition period. The disruption altitude is, in turn, found to increase with ionospheric density and to decrease with total voltage. The current displays oscillations around a mean value. The period of the oscillations is the same as the recurrence period of the double layer formations. The oscillation amplitude increases with increasing voltage, whereas the mean value of the current is independent of voltage in the 100 to 800 V range covered by our simulations. Instead, the mean value of the current is determined by the electron density at the ionospheric boundary.

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.

Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc iron layered double hydroxides by one-step coprecipitation route

NASA Astrophysics Data System (ADS)

Zhang, Hui; Wen, Xing; Wang, Yingxia

2007-05-01

Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Mössbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO 42--containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO 42--containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn 0.435·Fe II0.094·Fe III0.470·(OH) 2]·(SO 42-) 0.235·1.0H 2O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO 42--containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS.

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.

Effect of double-layer application on bond quality of adhesive systems.

PubMed

Fujiwara, Satoshi; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Imai, Arisa; Watanabe, Hidehiko; Erickson, Robert L; Latta, Mark A; Nakatsuka, Toshiyuki; Miyazaki, Masashi

2018-01-01

The aim of this study was to determine the effect of double-layer application of universal adhesives on the bond quality and compare to other adhesive systems. Two universal adhesives used were in this study: Scotchbond Universal (SU), [3M ESPE] and Prime & Bond elect (PE), [Dentsply Caulk]. The conventional single-step self-etch adhesives G-ӕnial Bond (GB), [GC Corporation.] and BeautiBond (BB), [Shofu Inc.], and a two-step self-etch adhesive, Optibond XTR (OX), [Kerr Corporation], were used as comparison adhesives. Shear bond strengths (SBS) and shear fatigue strengths (SFS) to human enamel and dentin were measured in single application mode and double application mode. For each test condition, 15 specimens were prepared for SBS testing and 30 specimens for SFS testing. Enamel and dentin SBS of the universal adhesives in the double application mode were significantly higher than those of the single application mode. In addition, the universal adhesives in the double application mode had significantly higher dentin SFS values than those of the single application mode. The two-step self-etch adhesive OX tended to have lower bond strengths in the double application mode, regardless of the test method or adherent substrate. The double application mode is effective in enhancing SBS and SFS of universal adhesives, but not conventional two-step self-etch adhesives. These results suggest that, although the double application mode may enhance the bonding quality of a universal adhesive, it may be counter-productive for two-step self-etch adhesives in clinical use. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Recent advances in polymer supporting layered double hydroxides nanocomposite for electrochemical biosensors

NASA Astrophysics Data System (ADS)

Dhanasekaran, T.; Padmanaban, A.; Gnanamoorthy, G.; Manigandan, R.; Praveen Kumar, S.; Stephen, A.; Narayanan, V.

2018-01-01

In recent years, layered double hydroxides (LDHs) materials having emerging due to their ability of intercalate a variety of anions, either organic or inorganic molecules. The most significance of the LDHs has been found potential applications in catalysis, wastewater treatment, and electrochemical sensors. The Mg-Al LDHs (MAL) and Poly-o-phenylenediamine @ Mg-Al LDHs (P-MAL) was prepared via simple one step hydrothermal method. As prepared material was characterized using many techniques such as, the structural and crystal phase was determined from XRD and Raman analyses. The functional groups were depicted using FT-IR spectroscopy. The optical propertied studied using diffuse reflectance spectroscopy UV-vis spectroscopy and the emission property were analyzed from Photoluminescence spectroscopy. The surface morphology and average particle size was analyzed using FESEM microscopy. The prepared polymer composite material P-MAL was further used for highly sensitive electrochemical detection towards dopamine (DA).

Influence of carbon conductive additives on electrochemical double-layer supercapacitor parameters

NASA Astrophysics Data System (ADS)

Kiseleva, E. A.; Zhurilova, M. A.; Kochanova, S. A.; Shkolnikov, E. J.; Tarasenko, A. B.; Zaitseva, O. V.; Uryupina, O. V.; Valyano, G. V.

2018-01-01

Electrochemical double-layer capacitors (EDLC) offer energy storage technology, highly demanded for rapid transition processes in transport and stationary applications, concerned with fast power fluctuations. Rough structure of activated carbon, widely used as electrode material because of its high specific area, leads to poor electrode conductivity. Therefore there is the need for conductive additive to decrease internal resistance and to achieve high specific power and high specific energy. Usually carbon blacks are widely used as conductive additive. In this paper electrodes with different conductive additives—two types of carbon blacks and single-walled carbon nanotubes—were prepared and characterized in organic electrolyte-based EDLC cells. Electrodes are based on original wood derived activated carbon produced by potassium hydroxide high-temperature activation at Joint Institute for High Temperatures RAS. Electrodes were prepared from slurry by cold-rolling. For electrode characterization cyclic voltammetry, impedance spectra analysis, equivalent series resistance measurements and galvanostatic charge-discharge were used.

The effect of interlayer anion on the reactivity of Mg-Al layered double hydroxides: improving and extending the customization capacity of anionic clays.

PubMed

Rojas, Ricardo; Bruna, Felipe; de Pauli, Carlos P; Ulibarri, M Ángeles; Giacomelli, Carla E

2011-07-01

Layered double hydroxides (LDHs) reactivity and interfacial behavior are closely interconnected and control particle properties relevant to the wide range of these solids' applications. Despite their importance, their relationship has been hardly described. In this work, chloride and dodecylsulfate (DDS(-)) intercalated LDHs are studied combining experimental data (electrophoretic mobility and contact angle measurements, hydroxyl and organic compounds uptake) and a simple mathematical model that includes anion-binding and acid-base reactions. This approach evidences the anion effect on LDHs interfacial behavior, reflected in the opposite particle charge and the different surface hydrophobic/hydrophilic character. LDHs reactivity are also determined by the interlayer composition, as demonstrated by the cation uptake capability of the DDS(-) intercalated sample. Consequently, the interlayer anion modifies the LDHs interfacial properties and reactivity, which in turn extends the customization capacity of these solids. Copyright © 2011 Elsevier Inc. All rights reserved.

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.

A secure communication using cascade chaotic computing systems on clinical decision support.

PubMed

Koksal, Ahmet Sertol; Er, Orhan; Evirgen, Hayrettin; Yumusak, Nejat

2016-06-01

Clinical decision support systems (C-DSS) provide supportive tools to the expert for the determination of the disease. Today, many of the support systems, which have been developed for a better and more accurate diagnosis, have reached a dynamic structure due to artificial intelligence techniques. However, in cases when important diagnosis studies should be performed in secret, a secure communication system is required. In this study, secure communication of a DSS is examined through a developed double layer chaotic communication system. The developed communication system consists of four main parts: random number generator, cascade chaotic calculation layer, PCM, and logical mixer layers. Thanks to this system, important patient data created by DSS will be conveyed to the center through a secure communication line.

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.

Electrically pumped 1.3 microm room-temperature InAs/GaAs quantum dot lasers on Si substrates by metal-mediated wafer bonding and layer transfer.

PubMed

Tanabe, Katsuaki; Guimard, Denis; Bordel, Damien; Iwamoto, Satoshi; Arakawa, Yasuhiko

2010-05-10

An electrically pumped InAs/GaAs quantum dot laser on a Si substrate has been demonstrated. The double-hetero laser structure was grown on a GaAs substrate by metal-organic chemical vapor deposition and layer-transferred onto a Si substrate by GaAs/Si wafer bonding mediated by a 380-nm-thick Au-Ge-Ni alloy layer. This broad-area Fabry-Perot laser exhibits InAs quantum dot ground state lasing at 1.31 microm at room temperature with a threshold current density of 600 A/cm(2). (c) 2010 Optical Society of America.

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.

Lidar observations of the planetary boundary layer

NASA Technical Reports Server (NTRS)

Melfi, S. H.; Spinhirne, J. D.; Palm, S. P.

1985-01-01

The application of an airborne downward-looking lidar to the study of organized cellular convection in the planetary boundary layer (PBL) over the ocean is described. The lidar consisted of a frequency doubled Nd-YAG 530 mm-wavelength laser whose axis was aligned colinearly with the optical axis of an all-reflecting 40 mm-diameter Newtonian telescope. The airborne lidar provided a unique observation of both microscale and mesoscale variations of the PBL top. The lidar data, presented as constant backscatter isopleth soundings, provide a visual indication of the presence of vertically organized convection cells. Comparisons of the lidar-derived PBL structure with both a conceptual model of the PBL and laboratory simulations of Deardorf et al. (1980) of a developing convective PBL showed that the observations are consistent with a model of mixing in the PBL, which involves a field of organized updrafts separated by downdrafts.

Reciprocity in spatial evolutionary public goods game on double-layered network

NASA Astrophysics Data System (ADS)

Kim, Jinho; Yook, Soon-Hyung; Kim, Yup

2016-08-01

Spatial evolutionary games have mainly been studied on a single, isolated network. However, in real world systems, many interaction topologies are not isolated but many different types of networks are inter-connected to each other. In this study, we investigate the spatial evolutionary public goods game (SEPGG) on double-layered random networks (DRN). Based on the mean-field type arguments and numerical simulations, we find that SEPGG on DRN shows very rich interesting phenomena, especially, depending on the size of each layer, intra-connectivity, and inter-connected couplings, the network reciprocity of SEPGG on DRN can be drastically enhanced through the inter-connected coupling. Furthermore, SEPGG on DRN can provide a more general framework which includes the evolutionary dynamics on multiplex networks and inter-connected networks at the same time.

Reciprocity in spatial evolutionary public goods game on double-layered network

PubMed Central

Kim, Jinho; Yook, Soon-Hyung; Kim, Yup

2016-01-01

Spatial evolutionary games have mainly been studied on a single, isolated network. However, in real world systems, many interaction topologies are not isolated but many different types of networks are inter-connected to each other. In this study, we investigate the spatial evolutionary public goods game (SEPGG) on double-layered random networks (DRN). Based on the mean-field type arguments and numerical simulations, we find that SEPGG on DRN shows very rich interesting phenomena, especially, depending on the size of each layer, intra-connectivity, and inter-connected couplings, the network reciprocity of SEPGG on DRN can be drastically enhanced through the inter-connected coupling. Furthermore, SEPGG on DRN can provide a more general framework which includes the evolutionary dynamics on multiplex networks and inter-connected networks at the same time. PMID:27503801

Highly Crystalline C8-BTBT Thin-Film Transistors by Lateral Homo-Epitaxial Growth on Printed Templates.

PubMed

Janneck, Robby; Pilet, Nicolas; Bommanaboyena, Satya Prakash; Watts, Benjamin; Heremans, Paul; Genoe, Jan; Rolin, Cedric

2017-11-01

Highly crystalline thin films of organic semiconductors offer great potential for fundamental material studies as well as for realizing high-performance, low-cost flexible electronics. The fabrication of these films directly on inert substrates is typically done by meniscus-guided coating techniques. The resulting layers show morphological defects that hinder charge transport and induce large device-to-device variability. Here, a double-step method for organic semiconductor layers combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal evaporation step is reported. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coatings. The resulting film is highly crystalline and features a mobility increased by a factor of three and a relative spread in device characteristics improved by almost half an order of magnitude. This method is easily adaptable to other coating techniques and offers a route toward the fabrication of high-performance, large-area electronics based on highly crystalline thin films of organic semiconductors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dislocation creation and void nucleation in FCC ductile metals under tensile loading: a general microscopic picture.

PubMed

Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

2014-11-10

Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

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

Simulation of diffuse-charge capacitance in electric double layer capacitors

NASA Astrophysics Data System (ADS)

Sun, Ning; Gersappe, Dilip

2017-01-01

We use a Lattice Boltzmann Model (LBM) in order to simulate diffuse-charge dynamics in Electric Double Layer Capacitors (EDLCs). Simulations are carried out for both the charge and the discharge processes on 2D systems of complex random electrode geometries (pure random, random spheres and random fibers). The steric effect of concentrated solutions is considered by using a Modified Poisson-Nernst-Planck (MPNP) equations and compared with regular Poisson-Nernst-Planck (PNP) systems. The effects of electrode microstructures (electrode density, electrode filler morphology, filler size, etc.) on the net charge distribution and charge/discharge time are studied in detail. The influence of applied potential during discharging process is also discussed. Our studies show how electrode morphology can be used to tailor the properties of supercapacitors.

Can ionophobic nanopores enhance the energy storage capacity of electric-double-layer capacitors containing nonaqueous electrolytes?

DOE PAGES

Lian, Cheng; Univ. of California, Riverside, CA; Liu, Honglai; ...

2016-08-22

The ionophobicity effect of nanoporous electrodes on the capacitance and the energy storage capacity of nonaqueous-electrolyte supercapacitors is studied by means of the classical density functional theory (DFT). It has been hypothesized that ionophobic nanopores may create obstacles in charging, but they store energy much more efficiently than ionophilic pores. In this paper, we find that, for both ionic liquids and organic electrolytes, an ionophobic pore exhibits a charging behavior different from that of an ionophilic pore, and that the capacitance–voltage curve changes from a bell shape to a two-hump camel shape when the pore ionophobicity increases. For electric-double-layer capacitorsmore » containing organic electrolytes, an increase in the ionophobicity of the nanopores leads to a higher capacity for energy storage. Without taking into account the effects of background screening, the DFT predicts that an ionophobic pore containing an ionic liquid does not enhance the supercapacitor performance within the practical voltage ranges. However, by using an effective dielectric constant to account for ion polarizability, the DFT predicts that, like an organic electrolyte, an ionophobic pore with an ionic liquid is also able to increase the energy stored when the electrode voltage is beyond a certain value. We find that the critical voltage for an enhanced capacitance in an ionic liquid is larger than that in an organic electrolyte. Finally, our theoretical predictions provide further understanding of how chemical modification of porous electrodes affects the performance of supercapacitors.« less

Double-Layer Structured CO2 Adsorbent Functionalized with Modified Polyethyleneimine for High Physical and Chemical Stability.

PubMed

Jeon, Sunbin; Jung, Hyunchul; Kim, Sung Hyun; Lee, Ki Bong

2018-06-18

CO 2 capture using polyethyleneimine (PEI)-impregnated silica adsorbents has been receiving a lot of attention. However, the absence of physical stability (evaporation and leaching of amine) and chemical stability (urea formation) of the PEI-impregnated silica adsorbent has been generally established. Therefore, in this study, a double-layer impregnated structure, developed using modified PEI, is newly proposed to enhance the physical and chemical stabilities of the adsorbent. Epoxy-modified PEI and diepoxide-cross-linked PEI were impregnated via a dry impregnation method in the first and second layers, respectively. The physical stability of the double-layer structured adsorbent was noticeably enhanced when compared to the conventional adsorbents with a single layer. In addition to the enhanced physical stability, the result of simulated temperature swing adsorption cycles revealed that the double-layer structured adsorbent presented a high potential working capacity (3.5 mmol/g) and less urea formation under CO 2 -rich regeneration conditions. The enhanced physical and chemical stabilities as well as the high CO 2 working capacity of the double-layer structured adsorbent were mainly attributed to the second layer consisting of diepoxide-cross-linked PEI.

Porous double-layer polymer tubing for the potential use in heterogeneous continuous flow reactions.

PubMed

Herwig, Gordon; Hornung, Christian H; Peeters, Gary; Ebdon, Nicholas; Savage, G Paul

2014-12-24

Functional polymer tubing with an OD of 1/16 or 1/8 in. was fabricated by a simple polymer coextrusion process. The tubing was made of an outer impervious polypropylene layer and an inner layer, consisting of a blend of a functional polymer, polyethylene-co-methacrylic acid, and a sacrificial polymer, polystyrene. After a simple solvent leaching step using common organic solvents, the polystyrene was removed, leaving behind a porous inner layer that contains functional carboxylic acid groups, which could then be used for the immobilization of target molecules. Solution-phase reactions using amines or isocyanates have proven successful for the immobilization of a series of small molecules and polymers. This flexible multilayered functional tubing can be easily cut to the desired length and connected via standard microfluidic fittings.

Plasmons in spatially separated double-layer graphene nanoribbons

NASA Astrophysics Data System (ADS)

Bagheri, Mehran; Bahrami, Mousa

2014-05-01

Motivated by innovative progresses in designing multi-layer graphene nanostructured materials in the laboratory, we theoretically investigate the Dirac plasmon modes of a spatially separated double-layer graphene nanoribbon system, made up of a vertically offset armchair and metallic graphene nanoribbon pair. We find striking features of the collective excitations in this novel Coulomb correlated system, where both nanoribbons are supposed to be either intrinsic (undoped/ungated) or extrinsic (doped/gated). In the former, it is shown the low-energy acoustical and the high-energy optical plasmon modes are tunable only by the inter-ribbon charge separation. In the later, the aforementioned plasmon branches are modified by the added doping factor. As a result, our model could be useful to examine the existence of a linear Landau-undamped low-energy acoustical plasmon mode tuned via the inter-ribbon charge separation as well as doping. This study might also be utilized for devising novel quantum optical waveguides based on the Coulomb coupled graphene nanoribbons.

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

Investigation on dynamical interaction between a heavy vehicle and road pavement

NASA Astrophysics Data System (ADS)

Yang, Shaopu; Li, Shaohua; Lu, Yongjie

2010-08-01

This paper presents a model for three-dimensional, heavy vehicle-pavement-foundation coupled system, which is modelled as a seven-DOF vehicle moving along a simply supported double-layer rectangular thin plate on a linear viscoelastic foundation. The vertical tyre force is described by a single point-contact model, while the pavement-foundation is modelled as a double-layer plate on a linear viscoelastic foundation. Using the Galerkin method and quick direct integral method, the dynamical behaviour of the vehicle-pavement-foundation coupled system is investigated numerically and compared with that of traditional vehicle system and pavement system. The effects of coupling action on vehicle body vertical acceleration, suspension deformations, tyre forces and pavement displacements are also obtained. The investigation shows that the coupling action could not be neglected even on a smooth road surface, such as highway. Thus, it is necessary to investigate the dynamics of vehicle and pavement simultaneously based on the vehicle-pavement-foundation coupled system.

Sol-gel derived electrode materials for supercapacitor applications

NASA Astrophysics Data System (ADS)

Lin, Chuan

1998-12-01

Electrochemical capacitors have been receiving increasing interest in recent years for use in energy storage systems because of their high energy and power density and long cycle lifes. Possible applications of electrochemical capacitors include high power pulsed lasers, hybrid power system for electric vehicles, etc. In this dissertation, the preparation of electrode materials for use as electrochemical capacitors has been studied using the sol-gel process. The high surface area electrode materials explored in this work include a synthetic carbon xerogel for use in a double-layer capacitor, a cobalt oxide xerogel for use in a pseudocapacitor, and a carbon-ruthenium xerogel composite, which utilizes both double-layer and faradaic capacitances. The preparation conditions of these materials were investigated in detail to maximize the surface area and optimize the pore size so that more energy could be stored while minimizing mass transfer limitations. The microstructures of the materials were also correlated with their performance as electrochemical capacitors to improve their energy and power densities. Finally, an idealistic mathematical model, including both double-layer and faradaic processes, was developed and solved numerically. This model can be used to perform the parametric studies of an electrochemical capacitor so as to gain a better understanding of how the capacitor works and also how to improve cell operations and electrode materials design.

Natural Underwater Adhesives

PubMed Central

Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

2011-01-01

The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent curing. PMID:21643511

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.

Relation between the ion size and pore size for an electric double-layer capacitor.

PubMed

Largeot, Celine; Portet, Cristelle; Chmiola, John; Taberna, Pierre-Louis; Gogotsi, Yury; Simon, Patrice

2008-03-05

The research on electrochemical double layer capacitors (EDLC), also known as supercapacitors or ultracapacitors, is quickly expanding because their power delivery performance fills the gap between dielectric capacitors and traditional batteries. However, many fundamental questions, such as the relations between the pore size of carbon electrodes, ion size of the electrolyte, and the capacitance have not yet been fully answered. We show that the pore size leading to the maximum double-layer capacitance of a TiC-derived carbon electrode in a solvent-free ethyl-methylimmidazolium-bis(trifluoro-methane-sulfonyl)imide (EMI-TFSI) ionic liquid is roughly equal to the ion size (approximately 0.7 nm). The capacitance values of TiC-CDC produced at 500 degrees C are more than 160 F/g and 85 F/cm(3) at 60 degrees C, while standard activated carbons with larger pores and a broader pore size distribution present capacitance values lower than 100 F/g and 50 F/cm(3) in ionic liquids. A significant drop in capacitance has been observed in pores that were larger or smaller than the ion size by just an angstrom, suggesting that the pore size must be tuned with sub-angstrom accuracy when selecting a carbon/ion couple. This work suggests a general approach to EDLC design leading to the maximum energy density, which has been now proved for both solvated organic salts and solvent-free liquid electrolytes.

Low driving voltage blue, green, yellow, red and white organic light-emitting diodes with a simply double light-emitting structure.

PubMed

Zhang, Zhensong; Yue, Shouzhen; Wu, Yukun; Yan, Pingrui; Wu, Qingyang; Qu, Dalong; Liu, Shiyong; Zhao, Yi

2014-01-27

Low driving voltage blue, green, yellow, red and white phosphorescent organic light-emitting diodes (OLEDs) with a common simply double emitting layer (D-EML) structure are investigated. Our OLEDs without any out-coupling schemes as well as n-doping strategies show low driving voltage, e.g. < 2.4 V for onset and < 3 V for 1000 cd/m2, and high efficiency of 32.5 lm/W (13.3%), 58.8 lm/W (14.3%), 55.1 lm/W (14.6%), 24.9 lm/W (13.7%) and 45.1 lm/W (13.5%) for blue, green, yellow, red and white OLED, respectively. This work demonstrates that the low driving voltages and high efficiencies can be simultaneously realized with a common simply D-EML structure.

Atomistic Molecular Dynamics Simulations of Charged Latex Particle Surfaces in Aqueous Solution.

PubMed

Li, Zifeng; Van Dyk, Antony K; Fitzwater, Susan J; Fichthorn, Kristen A; Milner, Scott T

2016-01-19

Charged particles in aqueous suspension form an electrical double layer at their surfaces, which plays a key role in suspension properties. For example, binder particles in latex paint remain suspended in the can because of repulsive forces between overlapping double layers. Existing models of the double layer assume sharp interfaces bearing fixed uniform charge, and so cannot describe aqueous binder particle surfaces, which are soft and diffuse, and bear mobile charge from ionic surfactants as well as grafted multivalent oligomers. To treat this industrially important system, we use atomistic molecular dynamics simulations to investigate a structurally realistic model of commercial binder particle surfaces, informed by extensive characterization of particle synthesis and surface properties. We determine the interfacial profiles of polymer, water, bound and free ions, from which the charge density and electrostatic potential can be calculated. We extend the traditional definitions of the inner and outer Helmholtz planes to our diffuse interfaces. Beyond the Stern layer, the simulated electrostatic potential is well described by the Poisson-Boltzmann equation. The potential at the outer Helmholtz plane compares well to the experimental zeta potential. We compare particle surfaces bearing two types of charge groups, ionic surfactant and multivalent oligomers, with and without added salt. Although the bare charge density of a surface bearing multivalent oligomers is much higher than that of a surfactant-bearing surface at realistic coverage, greater counterion condensation leads to similar zeta potentials for the two systems.

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

Enhanced removal of natural organic matters by calcined Mg/Al layered double hydroxide nanocrystalline particles: Adsorption, reusability and mechanism studies

NASA Astrophysics Data System (ADS)

Fang, Liping; Hou, Jingwei; Xu, Cuihong; Wang, Yaru; Li, Ji; Xiao, Feng; Wang, Dongsheng

2018-06-01

Natural organic matters (NOMs) can generate disinfection by-products during water treatment process, threatening to human health. However, the removal of NOM is still unsatisfactory in water treatment. Hence, this work investigated the removal efficiency of humic and fulvic acids (HA and FA) by layered double hydroxide (LDH) and its calcined forms under different conditions. Our results show that calcination of LDH at 500 °C can effectively enhance the NOM removal with adsorption capacities of 98.8 mg/g for HA and 97.6 mg/g for FA at pH 9.5. The removal efficiency of HA and FA notably increases by decreasing pH. The presence of SO42- and CO32- significantly suppresses the removal of HA or FA by CLDHs. The release of Al from LDH and CLDH is negligible and safe to aquatic organisms at pH > 6.5. Moreover, CLDH shows a good reusability for NOM removal in water treatment. The removal of HA and FA by CLDH is governed through electrostatic interactions and intercalation into the interlayers of LDH was not observed. Fluorescence and molecular weight analyses show that the microbial by-products with mid-molecular weight are more difficult to be removed than HA and FA. This study provides a new insight into the NOM removal using LDH and CLDH.

Fundamentally Addressing Bromine Storage through Reversible Solid-State Confinement in Porous Carbon Electrodes: Design of a High-Performance Dual-Redox Electrochemical Capacitor.

PubMed

Yoo, Seung Joon; Evanko, Brian; Wang, Xingfeng; Romelczyk, Monica; Taylor, Aidan; Ji, Xiulei; Boettcher, Shannon W; Stucky, Galen D

2017-07-26

Research in electric double-layer capacitors (EDLCs) and rechargeable batteries is converging to target systems that have battery-level energy density and capacitor-level cycling stability and power density. This research direction has been facilitated by the use of redox-active electrolytes that add faradaic charge storage to increase energy density of the EDLCs. Aqueous redox-enhanced electrochemical capacitors (redox ECs) have, however, performed poorly due to cross-diffusion of soluble redox couples, reduced cycle life, and low operating voltages. In this manuscript, we propose that these challenges can be simultaneously met by mechanistically designing a liquid-to-solid phase transition of oxidized catholyte (or reduced anolyte) with confinement in the pores of electrodes. Here we demonstrate the realization of this approach with the use of bromide catholyte and tetrabutylammonium cation that induces reversible solid-state complexation of Br 2 /Br 3 - . This mechanism solves the inherent cross-diffusion issue of redox ECs and has the added benefit of greatly stabilizing the reactive bromine generated during charging. Based on this new mechanistic insight on the utilization of solid-state bromine storage in redox ECs, we developed a dual-redox EC consisting of a bromide catholyte and an ethyl viologen anolyte with the addition of tetrabutylammonium bromide. In comparison to aqueous and organic electric double-layer capacitors, this system enhances energy by factors of ca. 11 and 3.5, respectively, with a specific energy of ∼64 W·h/kg at 1 A/g, a maximum power density >3 kW/kg, and cycling stability over 7000 cycles.

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.

An NMR Study of Biomimetic Fluorapatite – Gelatine Mesocrystals

PubMed Central

Vyalikh, Anastasia; Simon, Paul; Rosseeva, Elena; Buder, Jana; Scheler, Ulrich; Kniep, Rüdiger

2015-01-01

The mesocrystal system fluoroapatite—gelatine grown by double-diffusion is characterized by hierarchical composite structure on a mesoscale. In the present work we apply solid state NMR to characterize its structure on the molecular level and provide a link between the structural organisation on the mesoscale and atomistic computer simulations. Thus, we find that the individual nanocrystals are composed of crystalline fluorapatite domains covered by a thin boundary apatite-like layer. The latter is in contact with an amorphous layer, which fills the interparticle space. The amorphous layer is comprised of the organic matrix impregnated by isolated phosphate groups, Ca3F motifs and water molecules. Our NMR data provide clear evidence for the existence of precursor complexes in the gelatine phase, which were not involved in the formation of apatite crystals, proving hence theoretical predictions on the structural pre-treatment of gelatine by ion impregnation. The interfacial interactions, which may be described as the glue holding the composite materials together, comprise hydrogen bond interactions with the apatite PO43− groups. The reported results are in a good agreement with molecular dynamics simulations, which address the mechanisms of a growth control by collagen fibers, and with experimental observations of an amorphous cover layer in biominerals. PMID:26515127

Interacting Convective Processes in Kilauea Iki Lava Lake, Hawaii

NASA Astrophysics Data System (ADS)

Helz, R. T.

2007-12-01

Kilauea Iki lava lake formed in 1959 as a closed magma chamber of 40 million m3 of picritic magma. Repeated drilling and sampling of the lake allows recognition of processes of magmatic differentiation, and places time restrictions on the periods when they operated. Two processes, double-diffusive convection and finger diapirism, occurred because melt density decreases as olivine crystallization and re-equilibration proceeds, until after plagioclase begins to crystallize. Finger diapirism, described in previous work, occurred from 1961 to 1971 and affected most the lava lake between depths of 13 to 94 m. The period of inferred double- diffusive convection occurred between mid-1962 and 1964 and affected only the most olivine-poor part of the lava lake. Recent re-evaluation of petrographic and chemical data refine our understanding of this second process. The overall variation of bulk MgO content with depth in Kilauea Iki is an S-curve, consistent with gravitative redistribution of the abundant olivine phenocrysts present in the erupted lava. The olivine-poor zone (MgO <11 weight percent) is a sill-like volume found between depths of 21 to 43 m in the lake. This zone is bisected by a median layer containing more and slightly coarser olivine phenocrysts, which has an MgO content 2 weight percent higher than the minimum in the layers above and below. This configuration, not achievable by gravitative settling, suggests that the olivine-poor zone at some point contained a two-layer convective system. The upper and median layers of the olivine-poor zone contain a sparse population of augite microphenocrysts (0.2-0.4 mm in length), often in monomineralic clusters (1-3 mm in length), while the lower layer contains only olivine. Plagioclase and other phases occur only in the groundmass in all samples. If the layers developed before groundmass crystallization began, then the assemblage in the upper layer was olivine + augite, and was olivine-only in the lower. Because melt density decreases as temperature decreases in this part of the crystallization range and because the lava lake was strongly cooled from above, the conditions for double- diffusive convection, with splitting of the melt column into layers, were met. Core samples and temperature data obtained by drilling the lake in mid-1962 and late 1967 constrain the period of double-diffusive convection to the first half of that period. The process ceased without shifting the position of the median olivine-enriched layer downward, suggesting that it was very brief. Finger diapirism, already active in Kilauea Iki, was volumetrically more important, and passed through both layers. This overlapping process may have ended the broader convective process by reducing the thermal gradient that drove it. Although double- diffusive convection was a minor process in Kilauea Iki, it did occur in this closed magma system.

Amorphous indium-gallium-zinc-oxide thin-film transistors using organic-inorganic hybrid films deposited by low-temperature plasma-enhanced chemical vapor deposition for all dielectric layers

NASA Astrophysics Data System (ADS)

Hsu, Chao-Jui; Chang, Ching-Hsiang; Chang, Kuei-Ming; Wu, Chung-Chih

2017-01-01

We investigated the deposition of high-performance organic-inorganic hybrid dielectric films by low-temperature (close to room temperature) inductively coupled plasma chemical vapor deposition (ICP-CVD) with hexamethyldisiloxane (HMDSO)/O2 precursor gas. The hybrid films exhibited low leakage currents and high breakdown fields, suitable for thin-film transistor (TFT) applications. They were successfully integrated into the gate insulator, the etch-stop layer, and the passivation layer for bottom-gate staggered amorphous In-Ga-Zn-O (a-IGZO) TFTs having the etch-stop configuration. With the double-active-layer configuration having a buffer a-IGZO back-channel layer grown in oxygen-rich atmosphere for better immunity against plasma damage, the etch-stop-type bottom-gate staggered a-IGZO TFTs with good TFT characteristics were successfully demonstrated. The TFTs showed good field-effect mobility (μFE), threshold voltage (V th), subthreshold swing (SS), and on/off ratio (I on/off) of 7.5 cm2 V-1 s-1, 2.38 V, 0.38 V/decade, and 2.2 × 108, respectively, manifesting their usefulness for a-IGZO TFTs.

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.

Three-input gate logic circuits on chemically assembled single-electron transistors with organic and inorganic hybrid passivation layers

PubMed Central

Majima, Yutaka; Hackenberger, Guillaume; Azuma, Yasuo; Kano, Shinya; Matsuzaki, Kosuke; Susaki, Tomofumi; Sakamoto, Masanori; Teranishi, Toshiharu

2017-01-01

Abstract Single-electron transistors (SETs) are sub-10-nm scale electronic devices based on conductive Coulomb islands sandwiched between double-barrier tunneling barriers. Chemically assembled SETs with alkanethiol-protected Au nanoparticles show highly stable Coulomb diamonds and two-input logic operations. The combination of bottom-up and top-down processes used to form the passivation layer is vital for realizing multi-gate chemically assembled SET circuits, as this combination enables us to connect conventional complementary metal oxide semiconductor (CMOS) technologies via planar processes. Here, three-input gate exclusive-OR (XOR) logic operations are demonstrated in passivated chemically assembled SETs. The passivation layer is a hybrid bilayer of self-assembled monolayers (SAMs) and pulsed laser deposited (PLD) aluminum oxide (AlOx), and top-gate electrodes were prepared on the hybrid passivation layers. Top and two-side-gated SETs showed clear Coulomb oscillation and diamonds for each of the three available gates, and three-input gate XOR logic operation was clearly demonstrated. These results show the potential of chemically assembled SETs to work as logic devices with multi-gate inputs using organic and inorganic hybrid passivation layers. PMID:28634499

Three-input gate logic circuits on chemically assembled single-electron transistors with organic and inorganic hybrid passivation layers.

PubMed

Majima, Yutaka; Hackenberger, Guillaume; Azuma, Yasuo; Kano, Shinya; Matsuzaki, Kosuke; Susaki, Tomofumi; Sakamoto, Masanori; Teranishi, Toshiharu

2017-01-01

Single-electron transistors (SETs) are sub-10-nm scale electronic devices based on conductive Coulomb islands sandwiched between double-barrier tunneling barriers. Chemically assembled SETs with alkanethiol-protected Au nanoparticles show highly stable Coulomb diamonds and two-input logic operations. The combination of bottom-up and top-down processes used to form the passivation layer is vital for realizing multi-gate chemically assembled SET circuits, as this combination enables us to connect conventional complementary metal oxide semiconductor (CMOS) technologies via planar processes. Here, three-input gate exclusive-OR (XOR) logic operations are demonstrated in passivated chemically assembled SETs. The passivation layer is a hybrid bilayer of self-assembled monolayers (SAMs) and pulsed laser deposited (PLD) aluminum oxide (AlO[Formula: see text]), and top-gate electrodes were prepared on the hybrid passivation layers. Top and two-side-gated SETs showed clear Coulomb oscillation and diamonds for each of the three available gates, and three-input gate XOR logic operation was clearly demonstrated. These results show the potential of chemically assembled SETs to work as logic devices with multi-gate inputs using organic and inorganic hybrid passivation layers.

Double layer of platinum electrodes: Non-monotonic surface charging phenomena and negative double layer capacitance

NASA Astrophysics Data System (ADS)

Huang, Jun; Zhou, Tao; Zhang, Jianbo; Eikerling, Michael

2018-01-01

In this study, a refined double layer model of platinum electrodes accounting for chemisorbed oxygen species, oriented interfacial water molecules, and ion size effects in solution is presented. It results in a non-monotonic surface charging relation and a peculiar capacitance vs. potential curve with a maximum and possibly negative values in the potential regime of oxide-formation.

Organic electrical double layer transistors gated with ionic liquids

NASA Astrophysics Data System (ADS)

Xie, Wei; Frisbie, C. Daniel

2011-03-01

Transport in organic semiconductors gated with several types of ionic liquids has been systematically studied at charge densities larger than 1013 cm-2 . We observe a pronounced maximum in channel conductance for both p-type and n-type organic single crystals which is attributed to carrier localization at the semiconductor-electrolyte interface. Carrier mobility, as well as charge density and dielectric capacitance are determined through displacement current measurement and capacitance-voltage measurement. By using a larger-sized and spherical anion, tris(pentafluoroethyl)trifluorophosphate (FAP), effective carrier mobility in rubrene can be enhanced substantially up to 3.2 cm2 V-1 s -1 . Efforts have been made to maximize the charge density in rubrene single crystals, and at low temperature when higher gate bias can be applied, charge density can more than double the amount of that at room temperature, reaching 8*1013 cm-2 holes (0.4 holes per rubrene molecule). NSF MRSEC program at the University of Minnesota.

The Equivalent Electrokinetic Circuit Model of Ion Concentration Polarization Layer: Electrical Double Layer, Extended Space Charge and Electro-convection

NASA Astrophysics Data System (ADS)

Cho, Inhee; Huh, Keon; Kwak, Rhokyun; Lee, Hyomin; Kim, Sung Jae

2016-11-01

The first direct chronopotentiometric measurement was provided to distinguish the potential difference through the extended space charge (ESC) layer which is formed with the electrical double layer (EDL) near a perm-selective membrane. From this experimental result, the linear relationship was obtained between the resistance of ESC and the applied current density. Furthermore, we observed the step-wise distributions of relaxation time at the limiting current regime, confirming the existence of ESC capacitance other than EDL's. In addition, we proposed the equivalent electrokinetic circuit model inside ion concentration polarization (ICP) layer under rigorous consideration of EDL, ESC and electro-convection (EC). In order to elucidate the voltage configuration in chronopotentiometric measurement, the EC component was considered as the "dependent voltage source" which is serially connected to the ESC layer. This model successfully described the charging behavior of the ESC layer with or without EC, where both cases determined each relaxation time, respectively. Finally, we quantitatively verified their values utilizing the Poisson-Nernst-Planck equations. Therefore, this unified circuit model would provide a key insight of ICP system and potential energy-efficient applications.

Graphene-based stretchable and transparent moisture barrier

NASA Astrophysics Data System (ADS)

Won, Sejeong; Van Lam, Do; Lee, Jin Young; Jung, Hyun-June; Hur, Min; Kim, Kwang-Seop; Lee, Hak-Joo; Kim, Jae-Hyun

2018-03-01

We propose an alumina-deposited double-layer graphene (2LG) as a transparent, scalable, and stretchable barrier against moisture; this barrier is indispensable for foldable or stretchable organic displays and electronics. Both the barrier property and stretchability were significantly enhanced through the introduction of 2LG between alumina and a polymeric substrate. 2LG with negligible polymeric residues was coated on the polymeric substrate via a scalable dry transfer method in a roll-to-roll manner; an alumina layer was deposited on the graphene via atomic layer deposition. The effect of the graphene layer on crack generation in the alumina layer was systematically studied under external strain using an in situ micro-tensile tester, and correlations between the deformation-induced defects and water vapor transmission rate were quantitatively analyzed. The enhanced stretchability of alumina-deposited 2LG originated from the interlayer sliding between the graphene layers, which resulted in the crack density of the alumina layer being reduced under external strain.

Multilayered membranes with tuned well arrays to be used as regenerative patches.

PubMed

Martins, Nádia I; Sousa, Maria P; Custódio, Catarina A; Pinto, Vânia C; Sousa, Paulo J; Minas, Graça; Cleymand, Franck; Mano, João F

2017-07-15

Membranes have been explored as patches in tissue repair and regeneration, most of them presenting a flat geometry or a patterned texture at the nano/micrometer scale. Herein, a new concept of a flexible membrane featuring well arrays forming pore-like environments to accommodate cell culture is proposed. The processing of such membranes using polysaccharides is based on the production of multilayers using the layer-by-layer methodology over a patterned PDMS substrate. The detached multilayered membrane exhibits a layer of open pores at one side and a total thickness of 38±2.2µm. The photolithography technology used to produce the molds allows obtaining wells on the final membranes with a tuned shape and micro-scale precision. The influence of post-processing procedures over chitosan/alginate films with 100 double layers, including crosslinking with genipin or fibronectin immobilization, on the adhesion and proliferation of human osteoblast-like cells is also investigated. The results suggest that the presence of patterned wells affects positively cell adhesion, morphology and proliferation. In particular, it is seen that cells colonized preferentially the well regions. The geometrical features with micro to sub-millimeter patterned wells, together with the nano-scale organization of the polymeric components along the thickness of the film will allow to engineer highly versatile multilayered membranes exhibiting a pore-like microstructure in just one of the sides, that could be adaptable in the regeneration of multiple tissues. Flexible multilayered membranes containing multiple micro-reservoirs are found as potential regenerative patches. Layer-by-layer (LbL) methodology over a featured PDMS substrate is used to produce patterned membranes, composed only by natural-based polymers, that can be easily detached from the PDMS substrate. The combination of nano-scale control of the polymeric organization along the thickness of the chitosan/alginate (CHT/ALG) membranes, provided by LbL, together with the geometrical micro-scale features of the patterned membranes offers a uniqueness system that allows cells to colonize 3-dimensionally. This study provides a promising strategy to control cellular spatial organization that can face the region of the tissue to regenerate. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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.

Double Charge Ordering States and Spin Ordering State Observed in a RFe2O4 System

PubMed Central

Sun, Fei; Wang, Rui; Aku-Leh, C.; Yang, H. X.; He, Rui; Zhao, Jimin

2014-01-01

Charge, spin, and lattice degrees of orderings are of great interest in the layered quantum material RFe2O4 (R = Y, Er, Yb, Tm, and Lu) system. Recently many unique properties have been found using various experimental methods. However so far the nature of the two-dimensional (2D) charge ordering (CO) state is not clear and no observation of its fine structure in energy has been reported. Here we report unambiguous observation of double 2D CO states at relatively high temperature in a polycrystalline Er0.1Yb0.9Fe2O4 using Raman scattering. The energy gaps between the 3D and the double 2D states are 170 meV (41.2 THz) and 193 meV (46.6 THz), respectively. We also observed a spin ordering (SO) state at below 210 K with characteristic energy of 45 meV (10.7 THz). Our investigation experimentally identified new fine structures of quantum orders in the system, which also extends the capability of optical methods in investigating other layered quantum materials. PMID:25234133

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.

Investigating the development of double-peak subauroral ion drift (DSAID)

NASA Astrophysics Data System (ADS)

Horvath, Ildiko; Lovell, Brian C.

2017-04-01

This study focuses on the newly described ionospheric feature, called double-peak subauroral ion drift (DSAID), which is a subclass of the well-known single-peak SAID. Double-layer Region 2 (R2) field aligned currents (FACs) could be the main driver of DSAID. Our aim is to gain new insights into the development of DSAID during its two-stage progression. Observational results are provided by five scenarios, each demonstrating a certain progression sequence of DSAID. Results show that SAID/DSAID occurred during flux transfer events and was accompanied by flow channels (FCs) associated with dayside magnetopause (FC-2) and nightside magnetotail (FC-3) reconnections, with westward electrojet (eastward FC), and with auroral streamers (FC-4). In the premidnight magnetic local time (MLT) sector of stage 2, DSAID development was due to the short-circuiting of the reconnection-injected plasma jets during substorms or pseudobreakups. Thus, the related ring current pressure buildup enhanced the downward R2 FACs leading to double/multiple circuits forming double-layer R2 FACs. During the midnight MLT hours of stage 2, DSAID development was closely related to the westward traveling surge (WTS)/substorm current wedge (SCW). WTS/SCW-related strong upward R1 FACs closed with meriodional currents producing eastward and downward (i.e., downward R2 FAC-style) return currents enhancing the downward R2 FACs and thus leading to double/multiple circuits forming double-layer R2 FACs. Auroral streamers/FC-4 represent a substorm substructure and their occurrence with DSAID after stage 2 demonstrates that this substructure occasionally includes DSAID. Our results demonstrate also that the short-circuited system underlying SAID/DSAID acted sometimes as a current generator and sometimes as a voltage generator.

Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

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

Gao, Xiaorui, E-mail: gxr_1320@sina.com; School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189; Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA

Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and amore » diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.« less

Structure of the active form of human origin recognition complex and its ATPase motor module

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

Tocilj, Ante; On, Kin Fan; Yuan, Zuanning

Binding of the Origin Recognition Complex (ORC) to origins of replication marks the first step in the initiation of replication of the genome in all eukaryotic cells. Here, we report the structure of the active form of human ORC determined by X-ray crystallography and cryo-electron microscopy. The complex is composed of an ORC1/4/5 motor module lobe in an organization reminiscent of the DNA polymerase clamp loader complexes. A second lobe contains the ORC2/3 subunits. The complex is organized as a double-layered shallow corkscrew, with the AAA+ and AAA+-like domains forming one layer, and the winged-helix domains (WHDs) forming a topmore » layer. CDC6 fits easily between ORC1 and ORC2, completing the ring and the DNA-binding channel, forming an additional ATP hydrolysis site. Analysis of the ATPase activity of the complex provides a basis for understanding ORC activity as well as molecular defects observed in Meier-Gorlin Syndrome mutations.« less

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.

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.

Radioactive materials shipping cask anticontamination enclosure

DOEpatents

Belmonte, Mark S.; Davis, James H.; Williams, David A.

1982-01-01

An anticontamination device for use in storing shipping casks for radioactive materials comprising (1) a seal plate assembly; (2) a double-layer plastic bag; and (3) a water management system or means for water management.

Layering and Ordering in Electrochemical Double Layers

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

Liu, Yihua; Kawaguchi, Tomoya; Pierce, Michael S.

Electrochemical double layers (EDL) form at electrified interfaces. While Gouy-Chapman model describes moderately charged EDL, formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations, at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by x-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer is confirmed by glancing-incidence in-plane diffraction measurements.

Synthesis of (Hexaconazole-Zinc/Aluminum-Layered Double Hydroxide Nanocomposite) Fungicide Nanodelivery System for Controlling Ganoderma Disease in Oil Palm.

PubMed

Mustafa, Isshadiba F; Hussein, Mohd Zobir; Saifullah, Bullo; Idris, Abu Seman; Hilmi, Nur Hailini Z; Fakurazi, Sharida

2018-01-31

A fungicide, hexaconazole was successfully intercalated into the intergalleries of zinc/aluminum-layered double hydroxide (ZALDH) using the ion-exchange method. Due to the intercalation of hexaconazole, the basal spacing of the ZALDH was increased from 8.7 Å in ZALDH to 29.4 Å in hexaconazole-intercalated ZALDH (HZALDH). The intercalation of hexaconazole into the interlayer of the nanocomposite was confirmed using the Fourier-transform infrared (FTIR) study. This supramolecular chemistry intercalation process enhanced the thermal stability of the hexaconazole moiety. The fungicide loading was estimated to be 51.8%. The nanodelivery system also shows better inhibition toward the Ganoderma boninense growth than the counterpart, free hexaconazole. The results from this work have a great potential to be further explored for combating basal stem rot (BSR) disease in oil palm plantation.

Fundamental Study of Energy Storage for Electric Railway Combining Electric Double-layer Capacitors and Battery

NASA Astrophysics Data System (ADS)

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

The methods to stabilize power sources, which are the measures against voltage drop, power loading fluctuation, regenerative power lapse and so on, have been important issues in DC railway feeding circuits. Therefore, an energy storage medium that uses power efficiently and reduces above-mentioned problems is much concerned about. Electric double-layer capacitors (EDLC) can be charged and discharged rapidly in a short time with large power. On the other hand, a battery has a high energy density so that it is proper to be charged and discharged for a long time. Therefore, from a viewpoint of load pattern for electric railway, hybrid energy storage system combining both energy storage media may be effective. This paper introduces two methods for hybrid energy system theoretically, and describes the results of the fundamental tests.

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.

Beyond the Quantum Hall Effect: New Phases of 2D Electrons at High Magnetic Field

NASA Astrophysics Data System (ADS)

Eisenstein, James

2007-03-01

In this talk I will discuss recent experiments on high mobility single and double layer 2D electron systems in which collective phases lying outside the usual quantum Hall effect paradigm have been detected and studied. For example, in single layer 2D systems near half-filling of highly excited Landau levels new states characterized by a massive anisotropy in the electrical resistivity of the sample are observed at very low temperature. The anisotropy has been widely interpreted as the signature of a new class of correlated electron phases which incorporate a stripe-like charge density modulation. Orientational ordering of small striped domains at low temperatures accounts for the resistive anisotropy and is reminiscent of the isotropic-to-nematic phase transition in classical liquid crystals. Double layer 2D electron systems possess collective phases not present in single layer systems. In particular, when the total number of electrons in the bilayer equals the degeneracy of a single Landau level, an unusual phase appears at small layer separation. This phase possesses a novel broken symmetry, spontaneous interlayer phase coherence, which has a number of dramatic experimental signatures. The interlayer tunneling conductance develops a strong and very sharp resonance around zero bias resembling the dc Josephson effect. At the same time, both the longitudinal and Hall resistances of the sample vanish at low temperatures when currents are driven in opposite directions through the two layers. These, and other observations are broadly consistent with theories in which the broken symmetry phase can equivalently be described as a pseudospin ferromagnet or an (imperfect) excitonic superfluid. This work reflects a collaboration with M.P. Lilly, K.B. Cooper, I.B. Spielman, M. Kellogg, L.A. Tracy, L.N. Pfeiffer, and K.W. West.

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

Diffuse-charge dynamics of ionic liquids in electrochemical systems.

PubMed

Zhao, Hui

2011-11-01

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our simple scaling analysis suggests that the length scale √(λ*(D)l*(c)) accurately characterizes the double-layer structure of ionic liquids with strong electrostatic correlations where l*(c) is the electrostatic correlation length (in contrast, the Debye screening length λ*(D) is the primary double-layer length for electrolytes) and the response time of λ(D)(*3/2)L*/(D*l(c)(1/2)) (not λ*(D)L*/D* that is the primary charging time of electrolytes) is the correct charging time scale of ionic liquids with strong electrostatic correlations where D* is the diffusivity and L* is the separation length of the cell. With these two new scales, data of both electric potential versus distance from the electrode and the total diffuse charge versus time collapse onto each individual master curve in the presence of strong electrostatic correlations. In addition, the dependance of the total diffuse charge on steric effects, short-range correlations, and driving voltages is thoroughly examined. The results from the asymptotic analysis are compared favorably with those from full numerical simulations. Finally, the absorption of excess salt by the double layer creates a depletion region outside the double layer. Such salt depletion may bring a correction to the leading order terms and break down the weakly nonlinear analysis. A criterion which justifies the weakly nonlinear analysis is verified with numerical simulations.

Current-free double layers: A review

NASA Astrophysics Data System (ADS)

Singh, Nagendra

2011-12-01

During the last decade, there has been an upsurge in the research on current-free DLs (CFDLs). Research includes theory, laboratory measurements, and various applications of CFDLs ranging from plasma thrusters to acceleration of charged particles in space and astrophysical plasmas. The purpose of this review is to present a unified understanding of the basic plasma processes, which lead to the formation of CFDLs. The review starts with the discussion on early research on electric fields and double layers (DLs) and ion acceleration in planar plasma expansion. The review continues with the formation of DLs and rarefaction shocks (RFS) in expanding plasma with two electron populations with different temperatures. The basic theory mitigating the formation of a CFDL by two-electron temperature population is reviewed; we refer to such CFDLs as double layers structures formation by two-temperature electron populations (TET-CFDLs). Application of TET-CFDLS to ion acceleration in laboratory and space plasmas was discussed including the formation of stationary steady-state DLs. A quite different type of CFDLs forms in a helicon plasma device (HPD), in which plasma abruptly expands from a narrow plasma source tube into a wide diffusion tube with abruptly diverging magnetic fields. The formation mechanism of the CFDL in HPD, referred here as current free double layer structure in helicon plasma device (HPD-CFDL), and its applications are reviewed. The formation of a TET-CFDL is due to the self-consistent separation of the two electron populations parallel to the ambient magnetic field. In contrast, a HPD-CFDL forms due to self-consistent separation of electrons and ion perpendicular to the abruptly diverging magnetic field in conjunction with the conducting wall of the expansion chamber in the HPD. One-dimensional theoretical models of CFDLs based on steady-state solution of Vlasov-Poisson system of equations are briefly discussed. Applications of CFDLs ranging from helicon double-layer thrusters (HDLTs) to the accelerations of ions in space and astrophysical plasmas are summarized.

Architecture of optical sensor for recognition of multiple toxic metal ions from water.

PubMed

Shenashen, M A; El-Safty, S A; Elshehy, E A

2013-09-15

Here, we designed novel optical sensor based on the wormhole hexagonal mesoporous core/multi-shell silica nanoparticles that enabled the selective recognition and removal of these extremely toxic metals from drinking water. The surface-coating process of a mesoporous core/double-shell silica platforms by several consequence decorations using a cationic surfactant with double alkyl tails (CS-DAT) and then a synthesized dicarboxylate 1,5-diphenyl-3-thiocarbazone (III) signaling probe enabled us to create a unique hierarchical multi-shell sensor. In this design, the high loading capacity and wrapping of the CS-DAT and III organic moieties could be achieved, leading to the formation of silica core with multi-shells that formed from double-silica, CS-DAT, and III dressing layers. In this sensing system, notable changes in color and reflectance intensity of the multi-shelled sensor for Cu(2+), Co(2+), Cd(2+), and Hg(2+) ions, were observed at pH 2, 8, 9.5 and 11.5, respectively. The multi-shelled sensor is added to enable accessibility for continuous monitoring of several different toxic metal ions and efficient multi-ion sensing and removal capabilities with respect to reversibility, selectivity, and signal stability. Copyright © 2013 Elsevier B.V. All rights reserved.

A Theoretical Model for Predicting Residual Stress Generation in Fabrication Process of Double-Ceramic-Layer Thermal Barrier Coating System.

PubMed

Song, Yan; Wu, Weijie; Xie, Feng; Liu, Yilun; Wang, Tiejun

2017-01-01

Residual stress arisen in fabrication process of Double-Ceramic-Layer Thermal Barrier Coating System (DCL-TBCs) has a significant effect on its quality and reliability. In this work, based on the practical fabrication process of DCL-TBCs and the force and moment equilibrium, a theoretical model was proposed at first to predict residual stress generation in its fabrication process, in which the temperature dependent material properties of DCL-TBCs were incorporated. Then, a Finite Element method (FEM) has been carried out to verify our theoretical model. Afterwards, some important geometric parameters for DCL-TBCs, such as the thickness ratio of stabilized Zirconia (YSZ, ZrO2-8%Y2O3) layer to Lanthanum Zirconate (LZ, La2Zr2O7) layer, which is adjustable in a wide range in the fabrication process, have a remarkable effect on its performance, therefore, the effect of this thickness ratio on residual stress generation in the fabrication process of DCL-TBCs has been systematically studied. In addition, some thermal spray treatment, such as the pre-heating treatment, its effect on residual stress generation has also been studied in this work. It is found that, the final residual stress mainly comes from the cooling down process in the fabrication of DCL-TBCs. Increasing the pre-heating temperature can obviously decrease the magnitude of residual stresses in LZ layer, YSZ layer and substrate. With the increase of the thickness ratio of YSZ layer to LZ layer, magnitudes of residual stresses arisen in LZ layer and YSZ layer will increase while residual stress in substrate will decrease.

A Theoretical Model for Predicting Residual Stress Generation in Fabrication Process of Double-Ceramic-Layer Thermal Barrier Coating System

PubMed Central

Song, Yan; Wu, Weijie; Xie, Feng; Liu, Yilun; Wang, Tiejun

2017-01-01

Residual stress arisen in fabrication process of Double-Ceramic-Layer Thermal Barrier Coating System (DCL-TBCs) has a significant effect on its quality and reliability. In this work, based on the practical fabrication process of DCL-TBCs and the force and moment equilibrium, a theoretical model was proposed at first to predict residual stress generation in its fabrication process, in which the temperature dependent material properties of DCL-TBCs were incorporated. Then, a Finite Element method (FEM) has been carried out to verify our theoretical model. Afterwards, some important geometric parameters for DCL-TBCs, such as the thickness ratio of stabilized Zirconia (YSZ, ZrO2-8%Y2O3) layer to Lanthanum Zirconate (LZ, La2Zr2O7) layer, which is adjustable in a wide range in the fabrication process, have a remarkable effect on its performance, therefore, the effect of this thickness ratio on residual stress generation in the fabrication process of DCL-TBCs has been systematically studied. In addition, some thermal spray treatment, such as the pre-heating treatment, its effect on residual stress generation has also been studied in this work. It is found that, the final residual stress mainly comes from the cooling down process in the fabrication of DCL-TBCs. Increasing the pre-heating temperature can obviously decrease the magnitude of residual stresses in LZ layer, YSZ layer and substrate. With the increase of the thickness ratio of YSZ layer to LZ layer, magnitudes of residual stresses arisen in LZ layer and YSZ layer will increase while residual stress in substrate will decrease. PMID:28103275

Efficiently accounting for ion correlations in electrokinetic nanofluidic devices using density functional theory.

PubMed

Gillespie, Dirk; Khair, Aditya S; Bardhan, Jaydeep P; Pennathur, Sumita

2011-07-15

The electrokinetic behavior of nanofluidic devices is dominated by the electrical double layers at the device walls. Therefore, accurate, predictive models of double layers are essential for device design and optimization. In this paper, we demonstrate that density functional theory (DFT) of electrolytes is an accurate and computationally efficient method for computing finite ion size effects and the resulting ion-ion correlations that are neglected in classical double layer theories such as Poisson-Boltzmann. Because DFT is derived from liquid-theory thermodynamic principles, it is ideal for nanofluidic systems with small spatial dimensions, high surface charge densities, high ion concentrations, and/or large ions. Ion-ion correlations are expected to be important in these regimes, leading to nonlinear phenomena such as charge inversion, wherein more counterions adsorb at the wall than is necessary to neutralize its surface charge, leading to a second layer of co-ions. We show that DFT, unlike other theories that do not include ion-ion correlations, can predict charge inversion and other nonlinear phenomena that lead to qualitatively different current densities and ion velocities for both pressure-driven and electro-osmotic flows. We therefore propose that DFT can be a valuable modeling and design tool for nanofluidic devices as they become smaller and more highly charged. Copyright © 2011 Elsevier Inc. All rights reserved.

Soft x-ray imaging with incoherent sources

NASA Astrophysics Data System (ADS)

Wachulak, P.; Torrisi, A.; Ayele, M.; Bartnik, A.; Czwartos, J.; Wegrzyński, Ł.; Fok, T.; Parkman, T.; Vondrová, Š.; Turnová, J.; Odstrcil, M.; Fiedorowicz, H.

2017-05-01

In this work we present experimental, compact desk-top SXR microscope, the EUV microscope which is at this stage a technology demonstrator, and finally, the SXR contact microscope. The systems are based on laser-plasma EUV and SXR sources, employing a double stream gas puff target. The EUV and SXR full field microscopes, operating at 13.8 nm and 2.88 nm wavelengths, respectively, are capable of imaging nanostructures with a sub-50 nm spatial resolution with relatively short (seconds) exposure times. The SXR contact microscope operates in the "water-window" spectral range, to produce an imprint of the internal structure of the sample in a thin layer of SXR light sensitive photoresist. Applications of such desk-top EUV and SXR microscopes for studies of variety of different samples - test objects for resolution assessment and other objects such as carbon membranes, DNA plasmid samples, organic and inorganic thin layers, diatoms, algae and carcinoma cells, are also presented. Details about the sources, the microscopes as well as the imaging results for various objects will be presented and discussed. The development of such compact imaging systems may be important to the new research related to biological, material science and nanotechnology applications.

Development of effective power supply using electric double layer capacitor for static magnetic field coils in fusion plasma experiments.

PubMed

Inomoto, M; Abe, K; Yamada, T; Kuwahata, A; Kamio, S; Cao, Q H; Sakumura, M; Suzuki, N; Watanabe, T; Ono, Y

2011-02-01

A cost-effective power supply for static magnetic field coils used in fusion plasma experiments has been developed by application of an electric double layer capacitor (EDLC). A prototype EDLC power supply system was constructed in the form of a series LCR circuit. Coil current of 100 A with flat-top longer than 1 s was successfully supplied to an equilibrium field coil of a fusion plasma experimental apparatus by a single EDLC module with capacitance of 30 F. The present EDLC power supply has revealed sufficient performance for plasma confinement experiments whose discharge duration times are an order of several seconds.

Simulations of Cyclic Voltammetry for Electric Double Layers in Asymmetric Electrolytes: A Generalized Modified Poisson-Nernst-Planck Model

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

Wang, Hainan; Thiele, Alexander; Pilon, Laurent

2013-11-15

This paper presents a generalized modified Poisson–Nernst–Planck (MPNP) model derived from first principles based on excess chemical potential and Langmuir activity coefficient to simulate electric double-layer dynamics in asymmetric electrolytes. The model accounts simultaneously for (1) asymmetric electrolytes with (2) multiple ion species, (3) finite ion sizes, and (4) Stern and diffuse layers along with Ohmic potential drop in the electrode. It was used to simulate cyclic voltammetry (CV) measurements for binary asymmetric electrolytes. The results demonstrated that the current density increased significantly with decreasing ion diameter and/or increasing valency |z i| of either ion species. By contrast, the ionmore » diffusion coefficients affected the CV curves and capacitance only at large scan rates. Dimensional analysis was also performed, and 11 dimensionless numbers were identified to govern the CV measurements of the electric double layer in binary asymmetric electrolytes between two identical planar electrodes of finite thickness. A self-similar behavior was identified for the electric double-layer integral capacitance estimated from CV measurement simulations. Two regimes were identified by comparing the half cycle period τ CV and the “RC time scale” τ RC corresponding to the characteristic time of ions’ electrodiffusion. For τ RC ← τ CV, quasi-equilibrium conditions prevailed and the capacitance was diffusion-independent while for τ RC → τ CV, the capacitance was diffusion-limited. The effect of the electrode was captured by the dimensionless electrode electrical conductivity representing the ratio of characteristic times associated with charge transport in the electrolyte and that in the electrode. The model developed here will be useful for simulating and designing various practical electrochemical, colloidal, and biological systems for a wide range of applications.« less

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.

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

Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

NASA Astrophysics Data System (ADS)

Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

2018-05-01

A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

Ionic current rectification in organic solutions with quartz nanopipettes.

PubMed

Yin, Xiaohong; Zhang, Shudong; Dong, Yitong; Liu, Shujuan; Gu, Jing; Chen, Ye; Zhang, Xin; Zhang, Xianhao; Shao, Yuanhua

2015-09-01

The study of behaviors of ionic current rectification (ICR) in organic solutions with quartz nanopipettes is reported. ICR can be observed even in organic solutions using quartz pipettes with diameters varied from several to dozens of nanometers, and the direction of ICR is quite different from the ICR observed in aqueous phase. The influences of pore size, electrolyte concentration, and surface charge on the ICR have been investigated carefully. Water in organic solutions affects the direction and extent of ICR significantly. Mechanisms about the formation of an electrical double layer (EDL) on silica in organic solutions with different amount of water have been proposed. An improved method, which can be employed to detect trace water in organic solutions, has been implemented based on Au ultramicroelectrodes with cathodic differential pulse stripping voltammetry.

Design of signal reception and processing system of embedded ultrasonic endoscope

NASA Astrophysics Data System (ADS)

Li, Ming; Yu, Feng; Zhang, Ruiqiang; Li, Yan; Chen, Xiaodong; Yu, Daoyin

2009-11-01

Embedded Ultrasonic Endoscope, based on embedded microprocessor and embedded real-time operating system, sends a micro ultrasonic probe into coelom through the biopsy channel of the Electronic Endoscope to get the fault histology features of digestive organs by rotary scanning, and acquires the pictures of the alimentary canal mucosal surface. At the same time, ultrasonic signals are processed by signal reception and processing system, forming images of the full histology of the digestive organs. Signal Reception and Processing System is an important component of Embedded Ultrasonic Endoscope. However, the traditional design, using multi-level amplifiers and special digital processing circuits to implement signal reception and processing, is no longer satisfying the standards of high-performance, miniaturization and low power requirements that embedded system requires, and as a result of the high noise that multi-level amplifier brought, the extraction of small signal becomes hard. Therefore, this paper presents a method of signal reception and processing based on double variable gain amplifier and FPGA, increasing the flexibility and dynamic range of the Signal Reception and Processing System, improving system noise level, and reducing power consumption. Finally, we set up the embedded experiment system, using a transducer with the center frequency of 8MHz to scan membrane samples, and display the image of ultrasonic echo reflected by each layer of membrane, with a frame rate of 5Hz, verifying the correctness of the system.

Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications

NASA Astrophysics Data System (ADS)

Singh, Mahi R.; Guo, Jiaohan; J. Cid, José M.; De Hoyos Martinez, Jesús E.

2017-03-01

We study the light emission from a quantum emitter and double metallic nanoshell hybrid systems. Quantum emitters act as local sources which transmit their light efficiently due to a double nanoshell near field. The double nanoshell consists of a dielectric core and two outer nanoshells. The first nanoshell is made of a metal, and the second spacer nanoshell is made of a dielectric material or human serum albumin. We have calculated the fluorescence emission for a quantum emitter-double nanoshell hybrid when it is injected in an animal or a human body. Surface plasmon polariton resonances in the double nanoshell are calculated using Maxwell's equations in the quasi-static approximation, and the fluorescence emission is evaluated using the density matrix method in the presence of dipole-dipole interactions. We have compared our theory with two fluorescence experiments in hybrid systems in which the quantum emitter is Indocyanine Green or infrared fluorescent molecules. The outer spacer nanoshell of double metallic nanoshells consists of silica and human serum albumin with variable thicknesses. Our theory explains the enhancement of fluorescence spectra in both experiments. We find that the thickness of the spacer nanoshell layer increases the enhancement when the fluorescence decreases. The enhancement of the fluorescence depends on the type of quantum emitter, spacer layer, and double nanoshell. We also found that the peak of the fluorescence spectrum can be shifted by changing the shape and the size of the nanoshell. The fluorescence spectra can be switched from one peak to two peaks by removing the degeneracy of excitonic states in the quantum emitter. Hence, using these properties, one can use these hybrids as sensing and switching devices for applications in medicine.

White OLED in Hybrid Structure for Enhancing Color Purity.

PubMed

Kim, Dong-Eun; Kang, Min-Jae; Park, Gwang-Ryeol; Lee, Burm-Jong; Kwon, Young-Soo; Shin, Hoon-Kyu

2016-06-01

We synthesized the red emission material, bis(1,4-bis(5-phenyloxazol-2-yl)phenyl) iridium(picolate) [Ir-complexes] and the blue emission material, bis (2-(2-hydroxyphenyl) benzoxazolate)zinc [Zn(HPB)2]. White Organic Light Emitting Diodes were fabricated by using Zn(HPB)2 for a blue emitting layer, Ir-complexes for a red emitting layer and a tris (8-hydroxy quinoline)aluminum [Alq3] for a green emitting layer. The important experimental results obtained, white OLED was fabricated by using double emitting layers of Zn(HPB)2 and Alq3:Ir-complexes, and hole blocking layer of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline[BCP]. We also varied the thickness of BCP. When the thickness of BCP layer was 5 nm, white emission was achieved. We obtained a maximum luminance of 5400 cd/m2 at a current density of 650 mA/cm2. The CIE coordinates was (0.339, 0.323) at voltage of 10 V.

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

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

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

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.

Boosting Photon Harvesting in Organic Solar Cells with Highly Oriented Molecular Crystals via Graphene-Organic Heterointerface.

PubMed

Jo, Sae Byeok; Kim, Hyun Ho; Lee, Hansol; Kang, Boseok; Lee, Seongkyu; Sim, Myungsun; Kim, Min; Lee, Wi Hyoung; Cho, Kilwon

2015-08-25

Photon harvesting in organic solar cells is highly dependent on the anisotropic nature of the optoelectronic properties of photoactive materials. Here, we demonstrate an efficient approach to dramatically enhance photon harvesting in planar heterojunction solar cells by using a graphene-organic heterointerface. A large area, residue-free monolayer graphene is inserted at anode interface to serve as an atomically thin epitaxial template for growing highly orientated pentacene crystals with lying-down orientation. This anisotropic orientation enhances the overall optoelectronic properties, including light absorption, charge carrier lifetime, interfacial energetics, and especially the exciton diffusion length. Spectroscopic and crystallographic analysis reveal that the lying-down orientation persists until a thickness of 110 nm, which, along with increased exciton diffusion length up to nearly 100 nm, allows the device optimum thickness to be doubled to yield significantly enhanced light absorption within the photoactive layers. The resultant photovoltaic performance shows simultaneous increment in Voc, Jsc, and FF, and consequently a 5 times increment in the maximum power conversion efficiency than the equivalent devices without a graphene layer. The present findings indicate that controlling organic-graphene heterointerface could provide a design strategy of organic solar cell architecture for boosting photon harvesting.

Experimenting with mixing and layered convection in phono-trachytic magmas: Implications on reservoir dynamics

NASA Astrophysics Data System (ADS)

de Campos, C. P.; Civetta, L.; Dingwell, D. B.; Perugini, D.; Petrelli, M.; Fehr, T. K.

2006-12-01

Abundant geochemical and volcanological data on the Campanian Ignimbrite, (>200 km3, 39 ka) Phlegrean Fields, Italy, support the existence of a layered magmatic reservoir, which evolved via 1) replenishment of the chamber with trachytic magma and 2) short-term pre-eruptive mixing between new trachytic and phono- trachytic resident magmas. We have initiated an experimental program in order to constrain the dynamics of such mingling/mixing events. We used melted natural products from these two magmas of sub-equal but distinct composition, which are thought to have been involved in the origin of this magmatic system as end-members (phono-trachyte = end- member A and trachyte = end-member B). The two were then stirred together and sampled by experiment termination as a time series, ranging from 1-hour up to 1-week. Stirring under constant low flow velocity (0.5 rotations per minute) generated at first homogenization and mixing of the starting compositions. Then separate convection cells and compositional layering for major and minor elements emerged. Calculated density distributions along sections from the experimental glasses, after decoupling, are very similar to density distributions in aqueous systems under double-diffusive convection. In order to test double- diffusive decoupled convection in this system, we performed 87Sr/86Sr-isotopic and Sr- LA-ICP-MS- measurements, using the 25-hour experimental glasses. The effective chemical separation of different convection cells has been confirmed with clearly distinct isotopic signatures for both bottom and top cells. Comparison with natural samples from the Campanian Ignimbrite strengthens the importance of the role of a double-diffusive similar convection as a major differentiation process leading to layering in this system. Our results support the effectiveness of a DDC-driven fractionation for moderately high-silica magmas under high near-liquidus temperatures, before the onset of fractional crystallization.

Dislocation creation and void nucleation in FCC ductile metals under tensile loading: A general microscopic picture

PubMed Central

Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

2014-01-01

Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies. PMID:25382029

Layered double hydroxide of Cd-Al/C for the Mineralization and De-coloration of Dyes in Solar and Visible Light Exposure

NASA Astrophysics Data System (ADS)

Khan, Shahid Ali; Khan, Sher Bahadar; Asiri, Abdullah M.

2016-11-01

Cd-Al/C layered double hydroxide (Cd-Al/C-LDH) and Cd-Sb/C nanocatalyst are reported here for the de-coloration and mineralization of organic dyes. These catalysts were largely characterized by FESEM, EDS, XRD, FTIR, XPS, PL and DRS. The diffuse reflectance data showed a band gap at 2.92 and 2.983 eV for Cd-Al/C-LDH and Cd-Sb/C respectively. The band gap suggested that both catalysts work well in visible range. The photoluminescence spectra indicated a peak at 623 nm for both the catalysts which further support the effectiveness of the respective catalyst in visible range. Both catalysts also showed good recyclability and durability till 4th cycle. Five dyes, acridine orange (AO), malachite green (MG), crystal violet (CV), congo red (CR) and methyl orange (MO) were used in this experiment. Various parameters of different light intensity such as visible, ultraviolet, sunlight and dark condition are observed for the de-coloration of these dyes. The de-coloration phenomenon was proceeded through adsorption assisted phot-degradation. The low cost, abundant nature, good recyclability and better dye removal efficiency make these catalysts suitable candidates for the de-coloration and mineralization of organic dyes.

Layered double hydroxide/polyethylene terephthalate nanocomposites. Influence of the intercalated LDH anion and the type of polymerization heating method

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

Herrero, M.; Martinez-Gallegos, S.; Labajos, F.M.

2011-11-15

Conventional and microwave heating routes have been used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate had been previously intercalated in the LDH. PXRD and TEM were used to detect the degree of dispersion of the filler and the type of the polymeric composites obtained, and FTIR spectroscopy confirmed that the polymerization process had taken place. The thermal stability of these composites, as studied by thermogravimetric analysis, was enhanced when the microwave heating method was applied. Dodecyl sulphate wasmore » more effective than terephthalate to exfoliate the samples, which only occurred for the terephthalate ones under microwave irradiation. - Graphical abstract: Conventional and microwave heating routes were used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate was previously intercalated into the LDH. The microwave process improves the dispersion and the thermal stability of nanocomposites due to the interaction of the microwave radiation and the dipolar properties of EG and the homogeneous heating. Highlights: > LDH-PET compatibility is enhanced by preintercalation of organic anions. > Dodecylsulphate performance is much better than that of terephthalate. > Microwave heating improves the thermal stability of the composites. > Microwave heating improves as well the dispersion of the inorganic phase.« less

Simultaneous protection of organic p- and n-channels in complementary inverter from aging and bias-stress by DNA-base guanine/Al2O3 double layer.

PubMed

Lee, Junyeong; Hwang, Hyuncheol; Min, Sung-Wook; Shin, Jae Min; Kim, Jin Sung; Jeon, Pyo Jin; Lee, Hee Sung; Im, Seongil

2015-01-28

Although organic field-effect transistors (OFETs) have various advantages of lightweight, low-cost, mechanical flexibility, and nowadays even higher mobility than amorphous Si-based FET, stability issue under bias and ambient condition critically hinder its practical application. One of the most detrimental effects on organic layer comes from penetrated atmospheric species such as oxygen and water. To solve such degradation problems, several molecular engineering tactics are introduced: forming a kinetic barrier, lowering the level of molecule orbitals, and increasing the band gap. However, direct passivation of organic channels, the most promising strategy, has not been reported as often as other methods. Here, we resolved the ambient stability issues of p-type (heptazole)/or n-type (PTCDI-C13) OFETs and their bias-stability issues at once, using DNA-base small molecule guanine (C5H5N5O)/Al2O3 bilayer. The guanine protects the organic channels as buffer/and H getter layer between the channels and capping Al2O3, whereas the oxide capping resists ambient molecules. As a result, both p-type and n-type OFETs are simultaneously protected from gate-bias stress and 30 days-long ambient aging, finally demonstrating a highly stable, high-gain complementary-type logic inverter.

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.

High voltage electrochemical double layer capacitors using conductive carbons as additives

NASA Astrophysics Data System (ADS)

Michael, M. S.; Prabaharan, S. R. S.

We describe here an interesting approach towards electrochemical capacitors (ECCs) using graphite materials (as being used as conductive additives in rechargeable lithium-ion battery cathodes) in a Li + containing organic electrolyte. The important result is that we achieved a voltage window of >4 V, which is rather large, compared to the standard window of 2.5 V for ordinary electric double layer capacitors (DLCs). The capacitor performance was evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge techniques. From charge-discharge studies of the symmetrical device (for instance, SFG6 carbon electrode), a specific capacitance of up to 14.5 F/g was obtained at 16 mA/cm 2 current rate and at a low current rate (3 mA/cm 2), a higher value was obtained (63 F/g). The specific capacitance decreased about 25% after 1000 cycles compared to the initial discharge process. The performances of these graphites are discussed in the light of both double layer capacitance (DLC) and pseudocapacitance (battery-like behavior). The high capacitance obtained was not only derived from the current-transient capacitive behavior but is also attributed to pseudocapacitance associated with some kind of faradaic reaction, which could probably occur due to Li + intercalation/deintercalation reactions into graphitic layers of the carbons used. The ac impedance (electrochemical impedances spectroscopy, EIS) measurements were also carried out to evaluate the capacitor parameters such as equivalent series resistance (ESR) and frequency dependent capacitance ( Cfreq). Cyclic voltammetry measurements were also performed to evaluate the cycling behavior of the carbon electrodes and the non-rectangular shaped voltammograms revealed the non-zero time constant [ τ( RC)≠0] confirming that the current contains a transient as well as steady-state components.

The investigation of large field of view eyepiece with multilayer diffractive optical element

NASA Astrophysics Data System (ADS)

Fan, Changjiang

2014-11-01

In this paper, a light-small hybrid refractive/diffractive eyepiece for HMD is designed, which introduces a multilayer Diffractive Optical Element for the first time. This eyepiece optical system has a 22mm eye relief and 8mm exit pupil with 60° FOV. The multilayer DOE overcomes the difficulties of single-layer DOE and double-layer DOE using in the optical system, and improve the image contrast and the performance significantly due to the diffraction efficiency of the multilayer DOE is lager than 90% in wide waveband and large FOV range. The material of multilayer DOE are FCD1 for first layer, FD6 for second layer, PS for the filler layer. Moreover, the weight of the eyepiece system is only 8g, and the diameter of lens is 16mm. The MTF performance can satisfy the requirement of display with VGA resolution. Besides, the lateral color and distortion are 4.8% and 10μm, respectively. The properties of the helmet eyepiece system are excellent.

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.

NIR‐Triggered Crystal Phase Transformation of NiTi‐Layered Double Hydroxides Films for Localized Chemothermal Tumor Therapy

PubMed Central

Wang, Donghui; Ge, Naijian; Yang, Tingting; Peng, Feng; Qiao, Yuqin; Li, Qianwen

2018-01-01

Abstract Construction of localized drug‐eluting systems with synergistic chemothermal tumor‐killing abilities is promising for biomedical implants directly contacting with tumor tissues. In this study, an intelligent and biocompatible drug‐loading platform, based on a gold nanorods‐modified butyrate‐inserted NiTi‐layered double hydroxides film (Au@LDH/B), is prepared on the surface of nitinol alloy. The prepared films function as drug‐loading “sponges,” which pump butyrate out under near‐infrared (NIR) irradiation and resorb drugs in water when the NIR laser is shut off. The stimuli‐responsive release of butyrate is verified to be related with the NIR‐triggered crystal phase transformation of Au@LDH/B. In vitro and in vivo studies reveal that the prepared films possess excellent biosafety and high efficiency in synergistic thermochemo tumor therapy, showing a promising application in the construction of localized stimuli‐responsive drug‐delivery systems. PMID:29721424

Limiting factors for carbon based chemical double layer capacitors

NASA Technical Reports Server (NTRS)

Rose, M. Frank; Johnson, C.; Owens, T.; Stevens, B.

1993-01-01

The Chemical Double Layer (CDL) capacitor improves energy storage density dramatically when compared with conventional electrolytic capacitors. When compared to batteries, the CDL Capacitor is much less energy dense; however, the power density is orders of magnitude better. As a result, CDL-battery combinations present an interesting pulse power system with many potential applications. Due to the nature of the CDL it is inherently a low voltage device. The applications of the CDL can be tailored to auxiliary energy and burst mode storages which require fast charge/discharge cycles. Typical of the applications envisioned are power system backup, directed energy weapons concepts, electric automobiles, and electric actuators. In this paper, we will discuss some of the general characteristics of carbon-based CDL technology describing the structure, performance parameters, and methods of construction. Further, analytical and experimental results which define the state of the art are presented and described in terms of impact on applications.

Simulation of electric double-layer capacitors: evaluation of constant potential method

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Laird, Brian; Yang, Yang; Olmsted, David; Asta, Mark

2014-03-01

Atomistic simulations can play an important role in understanding electric double-layer capacitors (EDLCs) at a molecular level. In such simulations, typically the electrode surface is modeled using fixed surface charges, which ignores the charge fluctuation induced by local fluctuations in the electrolyte solution. In this work we evaluate an explicit treatment of charges, namely constant potential method (CPM)[1], in which the electrode charges are dynamically updated to maintain constant electrode potential. We employ a model system with a graphite electrode and a LiClO4/acetonitrile electrolyte, examined as a function of electrode potential differences. Using various molecular and macroscopic properties as metrics, we compare CPM simulations on this system to results using fixed surface charges. Specifically, results for predicted capacity, electric potential gradient and solvent density profile are identical between the two methods; However, ion density profiles and solvation structure yield significantly different results.

Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System.

PubMed

Lavrynenko, O M; Pavlenko, O Yu; Shchukin, Yu S

2016-12-01

The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations.

Improvement of pharmacokinetic and antitumor activity of layered double hydroxide nanoparticles by coating with PEGylated phospholipid membrane

PubMed Central

Yan, Mina; Zhang, Zhaoguo; Cui, Shengmiao; Lei, Ming; Zeng, Ke; Liao, Yunhui; Chu, Weijing; Deng, Yihui; Zhao, Chunshun

2014-01-01

Layered double hydroxide (LDH) has attracted considerable attention as a drug carrier. However, because of its poor in vivo behavior, polyethylene glycolylated (PEGylated) phospholipid must be used as a coformer to produce self-assembled core–shell nanoparticles. In the present study, we prepared a PEGylated phospholipid-coated LDH (PLDH) (PEG-PLDH) delivery system. The PEG-PLDH nanoparticles had an average size of 133.2 nm. Their core–shell structure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. In vitro liposome-cell-association and cytotoxicity experiments demonstrated its ability to be internalized by cells. In vivo studies showed that PEGylated phospholipid membranes greatly reduced the blood clearance rate of LDH nanoparticles. PEG-PLDH nanoparticles demonstrated a good control of tumor growth and increased the survival rate of mice. These results suggest that PEG-PLDH nanoparticles can be a useful drug delivery system for cancer therapy. PMID:25364245

Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System

NASA Astrophysics Data System (ADS)

Lavrynenko, O. M.; Pavlenko, O. Yu; Shchukin, Yu S.

2016-02-01

The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations.

Systemic toxicity induced by aggregated layered double hydroxide nanoparticles

PubMed Central

Yan, Mina; Yang, Chanzhen; Huang, Binyao; Huang, Zeqian; Huang, Liangfeng; Zhang, Xuefei; Zhao, Chunshun

2017-01-01

Layered double hydroxide (LDH) nanoparticles are emerging as one of the promising nanomaterials for biomedical applications, but their systemic toxicity in vivo has received little attention. In the present study, the effects of inorganic nanoparticle aggregation on their systemic toxicity were examined. Remarkably, aggregation was observed after the mixing of naked LDH nanoparticles with saline or erythrocytes. Significant accumulation of the naked LDH nanoparticles in the lungs of mice was detected 1 h after intravenous administration, and the survival rate of mice was 0% after 6 repeated injections. Furthermore, flocculent precipitates in the alveoli and congestion in the lung interstitium were observed in the dead mice. However, lipid membrane-coated LDH nanoparticles would not form aggregates and could be injected intravenously >6 times without causing death. These findings suggested that repeated injections of LDH were lethal even at low dose (30 mg/kg), and lipid membrane coating can be considered as an approach for reducing this risk. PMID:29042768

Study of Method for Designing the Power and the Capacitance of Fuel Cells and Electric Double-Layer Capacitors of Hybrid Railway Vehicle

NASA Astrophysics Data System (ADS)

Takizawa, Kenji; Kondo, Keiichiro

A hybrid railway traction system with fuel cells (FCs) and electric double layer-capacitors (EDLCs) is discussed in this paper. This system can save FC costs and absorb the regenerative energy. A method for designing FCs and EDLCs on the basis of the output power and capacitance, respectively, has not been reported, even though their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such design method is presented along with a train load profile and an energy management strategy. The design results obtained using the proposed method are verified by performing numerical simulations of a running train. These results reveal that the proposed method for designing the EDLCs and FCs on the basis of the capacitance and power, respectively, and by using a method for controlling the EDLC voltage is sufficiently effective in designing efficient EDLCs and FCs of hybrid railway traction systems.

Effect of concentration boundary layers on passive solute flows in a system of two polymeric membranes positioned in vertical planes.

PubMed

Slezak, Andrzej; Jasik-Slezak, Jolanta; Dworecki, Kazimierz

2003-01-01

The results of studies of influence of concentration boundary layers on passive diffusive transport in a double-membrane osmo-diffusive cell, containing a series of two (Ml and M(r)) vertically positioned, flat, microporous and symmetric polymer membranes (Nephrophane and Cellulose IMP-1) are presented in this paper. The membranes separated three compartments (l, m, r) containing binary, heterogeneous and non-ionic solutions (aqueous solutions of glucose or ethanol) or ternary non-electrolyte solutions (glucose solutions in 0.75 mol.l-1 solution of ethanol or ethanol solutions in 0.1 mol.l-1 aqueous solution of glucose). Solution concentrations fulfilled the condition C(k)l > C(k)m > C(k)r. The intermembrane compartment (m) was an infinitesimal solution layer. The volume of the m compartment and the volumes of the external (l and r) compartments fulfilled the condition Vl = Vr approximately 170 Vm. The tests were performed for configurations A and B of a double-membrane osmo-diffusive cell. In configuration A, the solution was located behind the M(r) membrane, and water was placed behind the Ml membrane, while in configuration B this sequence was reversed. The results obtained during experiment were interpreted in the categories of convective instability, which increased the value of diffusive permeability coefficient of the system: concentration boundary layer/membrane/concentration boundary layer.

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

Metal-Organic Nanosheets Formed via Defect-Mediated Transformation of a Hafnium Metal-Organic Framework.

PubMed

Cliffe, Matthew J; Castillo-Martínez, Elizabeth; Wu, Yue; Lee, Jeongjae; Forse, Alexander C; Firth, Francesca C N; Moghadam, Peyman Z; Fairen-Jimenez, David; Gaultois, Michael W; Hill, Joshua A; Magdysyuk, Oxana V; Slater, Ben; Goodwin, Andrew L; Grey, Clare P

2017-04-19

We report a hafnium-containing MOF, hcp UiO-67(Hf), which is a ligand-deficient layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its lower ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed "double cluster" (Hf 12 O 8 (OH) 14 ), analogous to the condensation of coordination polyhedra in oxide frameworks. In oxide frameworks, variable stoichiometry can lead to more complex defect structures, e.g., crystallographic shear planes or modules with differing compositions, which can be the source of further chemical reactivity; likewise, the layered hcp UiO-67 can react further to reversibly form a two-dimensional metal-organic framework, hxl UiO-67. Both three-dimensional hcp UiO-67 and two-dimensional hxl UiO-67 can be delaminated to form metal-organic nanosheets. Delamination of hcp UiO-67 occurs through the cleavage of strong hafnium-carboxylate bonds and is effected under mild conditions, suggesting that defect-ordered MOFs could be a productive route to porous two-dimensional materials.

Localization of the cannabinoid CB1 receptor and the 2-AG synthesizing (DAGLα) and degrading (MAGL, FAAH) enzymes in cells expressing the Ca2+-binding proteins calbindin, calretinin, and parvalbumin in the adult rat hippocampus

PubMed Central

Rivera, Patricia; Arrabal, Sergio; Cifuentes, Manuel; Grondona, Jesús M.; Pérez-Martín, Margarita; Rubio, Leticia; Vargas, Antonio; Serrano, Antonia; Pavón, Francisco J.; Suárez, Juan; Rodríguez de Fonseca, Fernando

2014-01-01

The retrograde suppression of the synaptic transmission by the endocannabinoid sn-2-arachidonoylglycerol (2-AG) is mediated by the cannabinoid CB1 receptors and requires the elevation of intracellular Ca2+ and the activation of specific 2-AG synthesizing (i.e., DAGLα) enzymes. However, the anatomical organization of the neuronal substrates that express 2-AG/CB1 signaling system-related molecules associated with selective Ca2+-binding proteins (CaBPs) is still unknown. For this purpose, we used double-label immunofluorescence and confocal laser scanning microscopy for the characterization of the expression of the 2-AG/CB1 signaling system (CB1 receptor, DAGLα, MAGL, and FAAH) and the CaBPs calbindin D28k, calretinin, and parvalbumin in the rat hippocampus. CB1, DAGLα, and MAGL labeling was mainly localized in fibers and neuropil, which were differentially organized depending on the hippocampal CaBPs-expressing cells. CB+1 fiber terminals localized in all hippocampal principal cell layers were tightly attached to calbindin+ cells (granular and pyramidal neurons), and calretinin+ and parvalbumin+ interneurons. DAGLα neuropil labeling was selectively found surrounding calbindin+ principal cells in the dentate gyrus and CA1, and in the calretinin+ and parvalbumin+ interneurons in the pyramidal cell layers of the CA1/3 fields. MAGL+ terminals were only observed around CA1 calbindin+ pyramidal cells, CA1/3 calretinin+ interneurons and CA3 parvalbumin+ interneurons localized in the pyramidal cell layers. Interestingly, calbindin+ pyramidal cells expressed FAAH specifically in the CA1 field. The identification of anatomically related-neuronal substrates that expressed 2-AG/CB1 signaling system and selective CaBPs should be considered when analyzing the cannabinoid signaling associated with hippocampal functions. PMID:25018703

Modeling the Dynamics and Export of Dissolved Organic Matter in the Northeastern U.S. Continental Shelf

NASA Technical Reports Server (NTRS)

Druon, J.N.; Mannino, A.; Signorini, Sergio R.; McClain, Charles R.; Friedrichs, M.; Wilkin, J.; Fennel, K.

2009-01-01

Continental shelves are believed to play a major role in carbon cycling due to their high productivity. Particulate organic carbon (POC) burial has been included in models as a carbon sink, but we show here that seasonally produced dissolved organic carbon (DOC) on the shelf can be exported to the open ocean by horizontal transport at similar rates (1-2 mol C/sq m/yr) in the southern U.S. Mid-Atlantic Bight (MAB). The dissolved organic matter (DOM) model imbedded in a coupled circulation-biogeochemical model reveals a double dynamics: the progressive release of dissolved organic nitrogen (DON) in the upper layer during summer increases the regenerated primary production by 30 to 300%, which, in turns ; enhances the DOC production mainly from phytoplankton exudation in the upper layer and solubilization of particulate organic matter (POM) deeper in the water column. This analysis suggests that DOM is a key element for better representing the ecosystem functioning and organic fluxes in models because DOM (1) is a major organic pool directly related to primary production, (2) decouples partially the carbon and nitrogen cycles (through carbon excess uptake, POM solubilization and DOM mineralization) and (3) is intimately linked to the residence time of water masses for its distribution and export.

Cross-diffusive effects on the onset of double-diffusive convection in a horizontal saturated porous fluid layer heated and salted from above

NASA Astrophysics Data System (ADS)

Rajib, Basu; C. Layek, G.

2013-05-01

Double-diffusive stationary and oscillatory instabilities at the marginal state in a saturated porous horizontal fluid layer heated and salted from above are investigated theoretically under the Darcy's framework for a porous medium. The contributions of Soret and Dufour coefficients are taken into account in the analysis. Linear stability analysis shows that the critical value of the Darcy—Rayleigh number depends on cross-diffusive parameters at marginally stationary convection, while the marginal state characterized by oscillatory convection does not depend on the cross-diffusion terms even if the condition and frequency of oscillatory convection depends on the cross-diffusive parameters. The critical value of the Darcy—Rayleigh number increases with increasing value of the solutal Darcy—Rayleigh number in the absence of cross-diffusive parameters. The critical Darcy—Rayleigh number decreases with increasing Soret number, resulting in destabilization of the system, while its value increases with increasing Dufour number, resulting in stabilization of the system at the marginal state characterized by stationary convection. The analysis reveals that the Dufour and Soret parameters as well as the porosity parameter play an important role in deciding the type of instability at the onset. This analysis also indicates that the stationary convection is followed by the oscillatory convection for certain fluid mixtures. It is interesting to note that the roles of cross-diffusive parameters on the double-diffusive system heated and salted from above are reciprocal to the double-diffusive system heated and salted from below.

Light emission from organic single crystals operated by electrolyte doping

NASA Astrophysics Data System (ADS)

Matsuki, Keiichiro; Sakanoue, Tomo; Yomogida, Yohei; Hotta, Shu; Takenobu, Taishi

2018-03-01

Light-emitting devices based on electrolytes, such as light-emitting electrochemical cells (LECs) and electric double-layer transistors (EDLTs), are solution-processable devices with a very simple structure. Therefore, it is necessary to apply this device structure into highly fluorescent organic materials for future printed applications. However, owing to compatibility problems between electrolytes and organic crystals, electrolyte-based single-crystal light-emitting devices have not yet been demonstrated. Here, we report on light-emitting devices based on organic single crystals and electrolytes. As the fluorescent materials, α,ω-bis(biphenylyl)terthiophene (BP3T) and 5,6,11,12-tetraphenylnaphthacene (rubrene) single crystals were selected. Using ionic liquids as electrolytes, we observed clear light emission from BP3T LECs and rubrene EDLTs.

Layer-by-layer assembled multilayer films of exfoliated layered double hydroxide and carboxymethyl-β-cyclodextrin for selective capacitive sensing of acephatemet.

PubMed

Gong, Jingming; Han, Xinmei; Zhu, Xiaolei; Guan, Zhangqiong

2014-11-15

Novel organic-inorganic hybrid ultrathin films were fabricated by alternate assembly of cationic exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets and carboxymethyl-β-cyclodextrin (CMCD) as a polyanion onto a glassy carbon electrode (GCE) via a layer-by-layer (LBL) approach. The multilayer films were then characterized by means of X-ray powder diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). These films were found to possess a long range stacking order in the normal direction of the substrate with a continuous and uniform morphology. Its electrochemical performance was systematically investigated. Our results demonstrate that such a newly designed (LDH/CMCD)n multilayer film, combining the individual properties of CMCD (a high supramolecule recognition and enrichment capability) together with LDH nanosheets (a rigid inorganic matrix), can be applied to a sensitive, simple, and label-free capacitive detection of acephatemet (AM). Molecular docking calculations further disclose that the selective sensing behavior toward AM may be attributed to the specific binding ability of CMCD to AM. Under the optimized conditions, the capacitive change of AM was proportional to its concentration ranging from 0.001 to 0.10 μg mL(-1) and 0.1 to 0.8 μg mL(-1) with a detection limit 0.6 ng mL(-1) (S/N=3). Toward the goal for practical applications, this simple probe was further evaluated by monitoring AM in real samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Interfacial thin films rupture and self-similarity

NASA Astrophysics Data System (ADS)

Ward, Margaret H.

2011-06-01

Two superposed thin layers of fluids are prone to interfacial instabilities due to London-van der Waals forces. Evolution equations for the film thicknesses are derived using lubrication theory. Using the intrinsic scales, for a single layer, results in a system with parametric dependence of four ratios of the two layers: surface tension, Hamaker constant, viscosity, and film thickness. In contrast to the single layer case, the bilayer system has two unstable eigenmodes: squeezing and bending. For some particular parameter regimes, the system exhibits the avoided crossing behavior, where the two eigenmodes are interchanged. Based on numerical analysis, the system evolves into four different rupture states: basal layer rupture, upper layer rupture, double layer rupture, and mixed layer rupture. The ratio of Hamaker constants and the relative film thickness of the two layers control the system dynamics. Remarkably, the line of avoided crossing demarks the transition region of mode mixing and energy transfer, affecting the scaling of the dynamical regime map consequentially. Asymptotic and numerical analyses are used to examine the self-similar ruptures and to extract the power law scalings for both the basal layer rupture and the upper layer rupture. The scaling laws for the basal layer rupture are the same as those of the single layer on top of a substrate. The scaling laws for the upper layer rupture are different: the lateral length scale decreases according to (tr-t)1/3 and the film thickness decreases according to (tr-t)1/6.

Enhanced spin-torque in double tunnel junctions using a nonmagnetic-metal spacer

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

Chen, C. H.; Cheng, Y. H.; Ko, C. W.

2015-10-12

This study proposes an enhancement in the spin-transfer torque of a magnetic tunnel junction (MTJ) designed with double-barrier layer structure using a nonmagnetic metal spacer, as a replacement for the ferromagnetic material, which is traditionally used in these double-barrier stacks. Our calculation results show that the spin-transfer torque and charge current density of the proposed double-barrier MTJ can be as much as two orders of magnitude larger than the traditional double-barrier one. In other words, the proposed double-barrier MTJ has a spin-transfer torque that is three orders larger than that of the single-barrier stack. This improvement may be attributed tomore » the quantum-well states that are formed in the nonmagnetic metal spacer and the resonant tunneling mechanism that exists throughout the system.« 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.

Increase in transmission loss of a double panel system by addition of mass inclusions to a poro-elastic layer: A comparison between theory and experiment

NASA Astrophysics Data System (ADS)

Idrisi, Kamal; Johnson, Marty E.; Toso, Alessandro; Carneal, James P.

2009-06-01

This paper is concerned with the modeling and optimization of heterogeneous (HG) blankets, which are used in this investigation to reduce the sound transmission through double panel systems. HG blankets consist of poro-elastic media with small embedded masses, which act similarly to a distributed mass-spring-damper-system. HG blankets have shown significant potential to reduce low frequency radiated sound from structures, where traditional poro-elastic materials have little effect. A mathematical model of a double panel system with an acoustic cavity and HG blanket was developed using impedance and mobility methods. The predicted responses of the source and the receiving panel due to a point force are validated with experimental measurements. The presented results indicate that proper tuning of the HG blankets can result in broadband noise reduction below 500 Hz with less than 10% added mass.

Development of a Hydrogen Gas Sensor Using a Double Saw Resonator System at Room Temperature

PubMed Central

Yunusa, Zainab; Hamidon, Mohd Nizar; Ismail, Alyani; Isa, Maryam Mohd; Yaacob, Mohd Hanif; Rahmanian, Saeed; Ibrahim, Siti Azlida; Shabaneh, Arafat A.A

2015-01-01

A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%. PMID:25730480

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.

On Practical Charge Injection at the Metal/Organic Semiconductor Interface

PubMed Central

Kumatani, Akichika; Li, Yun; Darmawan, Peter; Minari, Takeo; Tsukagoshi, Kazuhito

2013-01-01

We have revealed practical charge injection at metal and organic semiconductor interface in organic field effect transistor configurations. We have developed a facile interface structure that consisted of double-layer electrodes in order to investigate the efficiency through contact metal dependence. The metal interlayer with few nanometers thickness between electrode and organic semiconductor drastically reduces the contact resistance at the interface. The improvement has clearly obtained when the interlayer is a metal with lower standard electrode potential of contact metals than large work function of the contact metals. The electrode potential also implies that the most dominant effect on the mechanism at the contact interface is induced by charge transfer. This mechanism represents a step forward towards understanding the fundamental physics of intrinsic charge injection in all organic devices. PMID:23293741

Investigation of charge injection and transport behavior in multilayer structure consisted of ferromagnetic metal and organic polymer under external fields

NASA Astrophysics Data System (ADS)

Zhao, Hua; Meng, Wei-Feng

2017-10-01

In this paper a five layer organic electronic device with alternately placed ferromagnetic metals and organic polymers: ferromagnetic metal/organic layer/ferromagnetic metal/organic layer/ferromagnetic metal, which is injected a spin-polarized electron from outsides, is studied theoretically using one-dimensional tight binding model Hamiltonian. We calculated equilibrium state behavior after an electron with spin is injected into the organic layer of this structure, charge density distribution and spin polarization density distribution of this injected spin-polarized electron, and mainly studied possible transport behavior of the injected spin polarized electron in this multilayer structure under different external electric fields. We analyze the physical process of the injected electron in this multilayer system. It is found by our calculation that the injected spin polarized electron exists as an electron-polaron state with spin polarization in the organic layer and it can pass through the middle ferromagnetic layer from the right-hand organic layer to the left-hand organic layer by the action of increasing external electric fields, which indicates that this structure may be used as a possible spin-polarized charge electronic device and also may provide a theoretical base for the organic electronic devices and it is also found that in the boundaries between the ferromagnetic layer and the organic layer there exist induced interface local dipoles due to the external electric fields.

Tracers and constituents indicating the nature of organic fluxes, their origin and the effect of environmental conditions

NASA Astrophysics Data System (ADS)

Gadel, F.; Puigbó, A.; Alcan˜iz, J. M.; Charrière, B.; Serve, L.

1990-09-01

The nature of particulate organic matter was studied in suspended material sampled by bottles, particles collected by sediment traps and deposits from deltaic and open sea ecosystems of the northwestern Mediterranean. Elemental analyses were combined with pyrolysis-gas chromatography-mass spectrometry and with analysis of individual compounds such as phenols separated by high-performance liquid chromatography. In the Rhoˆne delta, a multilayered system was observed. The surficial turbid layer was enriched with fresh material of river origin. Organic matter was more altered and richer in phenols in the bottom nepheloid layer. The river regime determined the nature and quantity of suspended material: when in spate, degraded organic matter previously deposited in the river bed was transported to the sea, thereby inducing an increase of pyrolysis derived aromatic hydrocarbons. On the other hand, phenolic aldehydes increased in the bottom nepheloid layer. When water level was low, organic matter seemed to be of more local origin. The content of phenols and nitrogen-containing compounds increased. The influence of the Rhoˆne River decreased off the mouth, when terrestrial markers were diluted by products deriving from phytoplanktonic activity. Compared with suspended material, trapped organic matter was coarser, more degraded and contained more aromatic hydrocarbons. It was different in nature and size, indicating that it was trapped over a longer period. Deposits contained altered organic matter resulting from degrading processes in the water column. Sediments showed a double trend off the mouth of the river; an increase in nitrogen-containing compounds, indicating a more marine character, and a decrease in phenols and carbohydrates deriving from the terrestrial ligno-cellulosic complex. In the southwestern part of the Gulf of Lions, in the Teˆt prodelta, organic matter from sediment traps was fresher than in the Rhoˆne delta. Phenols and some carbohydrates rapidly decreased from the prodelta due to a lower runoff. During the spate, suspended material was rapidly deposited and sediments were enriched in terrestrial phenols. In the open sea environment, in the Lacaze-Duthiers Canyon at 645 m, in summer, the euphotic zone was rich in amino-sugars and contained a large diversity of phenols deriving from fish fecal pellets. In winter/spring, the development of phytoplanktonic blooms in surficial layers led to high contents of nitrogenous compounds. In deeper layers, the nature of organic matter was different from surficial layers in summer and more homogeneous in winter, although a flux of degraded material rich in pyrolysis-derived aromatic hydrocarbons and poor in nitrogenous compounds progressively sank towards the bottom. The two marine prodeltas were compared: organic matter was more degraded in suspended material and sediments collected in the submarine delta of the Rhoˆne River. Organic material originating from the river was transported further offshore, as indicated by a higher content of aromatic hydrocarbons and phenols. In the southwestern part of the Gulf of Lions, the prodelta reflected the influence of local rivers, with lower discharges.

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.

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.

Local, global, and nonlinear screening in twisted double-layer graphene

DOE PAGES

Lu, Chih -Pin; Rodriguez-Vega, Martin; Li, Guohong; ...

2016-06-02

One-atom-thick crystalline layers and their vertical heterostructures carry the promise of designer electronic materials that are unattainable by standard growth techniques. To realize their potential it is necessary to isolate them from environmental disturbances, in particular those introduced by the substrate. However, finding and characterizing suitable substrates, and minimizing the random potential fluctuations they introduce, has been a persistent challenge in this emerging field. In this paper, we show that Landau-level (LL) spectroscopy offers the unique capability to quantify both the reduction of the quasiparticles’ lifetime and the long-range inhomogeneity due to random potential fluctuations. Harnessing this technique together withmore » direct scanning tunneling microscopy and numerical simulations we demonstrate that the insertion of a graphene buffer layer with a large twist angle is a very effective method to shield a 2D system from substrate interference that has the additional desirable property of preserving the electronic structure of the system under study. Finally, we further show that owing to its remarkable nonlinear screening capability a single graphene buffer layer provides better shielding than either increasing the distance to the substrate or doubling the carrier density and reduces the amplitude of the potential fluctuations in graphene to values even lower than the ones in AB-stacked bilayer graphene.« less

Local, global, and nonlinear screening in twisted double-layer graphene

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

Lu, Chih -Pin; Rodriguez-Vega, Martin; Li, Guohong

One-atom-thick crystalline layers and their vertical heterostructures carry the promise of designer electronic materials that are unattainable by standard growth techniques. To realize their potential it is necessary to isolate them from environmental disturbances, in particular those introduced by the substrate. However, finding and characterizing suitable substrates, and minimizing the random potential fluctuations they introduce, has been a persistent challenge in this emerging field. In this paper, we show that Landau-level (LL) spectroscopy offers the unique capability to quantify both the reduction of the quasiparticles’ lifetime and the long-range inhomogeneity due to random potential fluctuations. Harnessing this technique together withmore » direct scanning tunneling microscopy and numerical simulations we demonstrate that the insertion of a graphene buffer layer with a large twist angle is a very effective method to shield a 2D system from substrate interference that has the additional desirable property of preserving the electronic structure of the system under study. Finally, we further show that owing to its remarkable nonlinear screening capability a single graphene buffer layer provides better shielding than either increasing the distance to the substrate or doubling the carrier density and reduces the amplitude of the potential fluctuations in graphene to values even lower than the ones in AB-stacked bilayer graphene.« less

Double-Layer Mediated Electromechanical Response of Amyloid Fibrils in Liquid Environment

PubMed Central

Nikiforov, M.P.; Thompson, G.L.; Reukov, V.V.; Jesse, S.; Guo, S.; Rodriguez, B.J.; Seal, K.; Vertegel, A.A.; Kalinin, S.V.

2010-01-01

Harnessing electrical bias-induced mechanical motion on the nanometer and molecular scale is a critical step towards understanding the fundamental mechanisms of redox processes and implementation of molecular electromechanical machines. Probing these phenomena in biomolecular systems requires electromechanical measurements be performed in liquid environments. Here we demonstrate the use of band excitation piezoresponse force microscopy for probing electromechanical coupling in amyloid fibrils. The approaches for separating the elastic and electromechanical contributions based on functional fits and multivariate statistical analysis are presented. We demonstrate that in the bulk of the fibril the electromechanical response is dominated by double-layer effects (consistent with shear piezoelectricity of biomolecules), while a number of electromechanically active hot spots possibly related to structural defects are observed. PMID:20088597

Anomalous Coulomb oscillation in crossed carbon nanotubes

NASA Astrophysics Data System (ADS)

Baek, Seung Jae; Lee, Dongsu; Park, Seung Joo; Park, Yung Woo; Svensson, Johannes; Jonson, Mats; Campbell, Eleanor E. B.

2008-03-01

Single-walled carbon nanotube (SWCNT) crossed junctions separated by an insulating layer were fabricated to investigate the double quantum dot modulated by a single gate (DQD-sG). Anomalous Coulomb oscillations were observed on the lower CNT at low temperature, where the behavior was interpreted by the concept of a double quantum dot (DQD) system http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id =APPLAB000089000023233107000001&idtype=cvips&gifs=yes [1]. To understand it more clearly, we have intentionally fabricated crossed CNTs without oxide layer in between. The observed anomalous Coulomb oscillations indicate that the contact resistance between the two tubes becomes a potential barrier splitting the initial single QD into the DQD, and the back-gate modulates the energy levels of the DQD.

Intrinsic phonon properties of double-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Tran, H. N.; Levshov, D. I.; Nguyen, V. C.; Paillet, M.; Arenal, R.; Than, X. T.; Zahab, A. A.; Yuzyuk, Y. I.; Phan, N. M.; Sauvajol, J.-L.; Michel, T.

2017-03-01

Double-walled carbon nanotubes (DWNT) are made of two concentric and weakly van der Waals coupled single-walled carbon nanotubes (SWNT). DWNTs are the simplest systems for studying the mechanical and electronic interactions between concentric carbon layers. In this paper we review recent results concerning the intrinsic features of phonons of DWNTs obtained from Raman experiments performed on index-identified DWNTs. The effect of the interlayer distance on the strength of the mechanical and electronic coupling between the layers, and thus on the frequencies of the Raman-active modes, namely the radial breathing-like modes (RBLMs) and G-modes, are evidenced and discussed. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

PWM Inverter with Voltage Boosters with Regenerating Capability Augmented by Electric Double-Layer Capacitor

NASA Astrophysics Data System (ADS)

Yamamoto, Kichiro; Imakiire, Akihiro; Iimori, Kenichi

An interior permanent magnet (IPM) motor drive system which has regenerating capability augmented by electric double-layer capacitors (EDLCs) is proposed. In the proposed system, EDLCs are arranged in series with batteries so that a lesser number of the EDLCs and batteries will be required. The proposed system has two bi-directional voltage boosters: one is for both the batteries and EDLCs to control the dc-link voltage of a PWM inverter and the other is for only the EDLCs and is used to control the energy flow from and to the EDLCs. In this paper, a strategy to control the energy flow to and from the EDLCs is explained and its effectiveness is confirmed by simulation and experimental results. Furthermore, the efficiencies of the voltage booster, inverter, PM motor, and whole system are measured for the system with the basic configuration, i.e., which consists of only one bi-directional voltage booster and PWM inverter. Then, the steady-state characteristics are determined. Finally, the efficiency of the voltage boosters in the proposed system is determined, and the advantage of the proposed PM motor drive system is discussed.

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

Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.

PubMed

Lemaire, Paul C; Zhao, Junjie; Williams, Philip S; Walls, Howard J; Shepherd, Sarah D; Losego, Mark D; Peterson, Gregory W; Parsons, Gregory N

2016-04-13

Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.

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.

Anti-stiction coating for mechanically tunable photonic crystal devices.

PubMed

Petruzzella, M; Zobenica, Ž; Cotrufo, M; Zardetto, V; Mameli, A; Pagliano, F; Koelling, S; van Otten, F W M; Roozeboom, F; Kessels, W M M; van der Heijden, R W; Fiore, A

2018-02-19

A method to avoid the stiction failure in nano-electro-opto-mechanical systems has been demonstrated by coating the system with an anti-stiction layer of Al 2 O 3 grown by atomic layer deposition techniques. The device based on a double-membrane photonic crystal cavity can be reversibly operated from the pull-in back to its release status. This enables to electrically switch the wavelength of a mode over ~50 nm with a potential modulation frequency above 2 MHz. These results pave the way to reliable nano-mechanical sensors and optical switches.

In Situ Clay Formation: Evaluation of a Proposed New Technology for Stable Containment Barriers

DTIC Science & Technology

2004-03-01

situ layered double hydroxide precipitation........... 23 4.2.1 Solution preparation and column mixing...22 Table 4.2 Summary of in situ precipitation of layered double hydroxide (LDH...effect on permeability for the smallest volume precipitated is sheet silicates or layered -clay phases (hereafter called “clays”). In natural

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.

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.

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.

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.

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.

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.

Structure of the active form of human origin recognition complex and its ATPase motor module

PubMed Central

Tocilj, Ante; On, Kin Fan; Yuan, Zuanning; Sun, Jingchuan; Elkayam, Elad; Li, Huilin; Stillman, Bruce; Joshua-Tor, Leemor

2017-01-01

Binding of the Origin Recognition Complex (ORC) to origins of replication marks the first step in the initiation of replication of the genome in all eukaryotic cells. Here, we report the structure of the active form of human ORC determined by X-ray crystallography and cryo-electron microscopy. The complex is composed of an ORC1/4/5 motor module lobe in an organization reminiscent of the DNA polymerase clamp loader complexes. A second lobe contains the ORC2/3 subunits. The complex is organized as a double-layered shallow corkscrew, with the AAA+ and AAA+-like domains forming one layer, and the winged-helix domains (WHDs) forming a top layer. CDC6 fits easily between ORC1 and ORC2, completing the ring and the DNA-binding channel, forming an additional ATP hydrolysis site. Analysis of the ATPase activity of the complex provides a basis for understanding ORC activity as well as molecular defects observed in Meier-Gorlin Syndrome mutations. DOI: http://dx.doi.org/10.7554/eLife.20818.001 PMID:28112645

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

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.

Molecular dynamics simulation studies of ionic liquid electrolytes for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Hu, Zongzhi

Molecular Dynamics (MD) simulation has been performed on various Electric Double Layer Capacitors (EDLCs) systems with different Room Temperature Ionic Liquids (RTILs) as well as different structures and materials of electrodes using a computationally efficient, low cost, united atom (UA)/explicit atom (EA) force filed. MD simulation studies on two 1-butyl-3-methylimidazolium (BMIM) based RTILs, i.e., [BMIM][BF4] and [BMIM][PF6], have been conducted on both atomic flat and corrugated graphite as well as (001) and (011) gold electrode surfaces to understand the correlations between the Electric Double Layer (EDL) structure and their corresponding differential capacitance (DC). Our MD simulations have strong agreement with some experimental data. The structures of electrodes also have a strong effect on the capacitance of EDLCs. MD simulations have been conducted on RTILs of N-methyl-N- propylpyrrolidinium [pyr13] and bis(fluorosulfonyl)imide (FSI) as well as [BMIM][PF6] on both curvature electrodes (fullerenes, nanotube, nanowire) and atomic flat electrode surfaces. It turns out that the nanowire electrode systems have the largest capacitance, following by fullerene systems. Nanotube electrode systems have the smallest capacitance, but they are still larger than that of atomically flat electrode system. Also, RTILs with slightly different chemical structure such as [Cnmim], n = 2, 4, 6, and 8, FSI and bis(trifluoromethylsulfonyl)imide (TFSI), have been examined by MD simulation on both flat and nonflat graphite electrode surfaces to study the effect of cation and anion's chemical structures on EDL structure and DC. With prismatic (nonflat) graphite electrodes, a transition from a bell-shape to a camel-shape DC dependence on electrode potential was observed with increase of the cation alkyl tail length for FSI systems. In contrast, the [Cnmim][TFSI] ionic liquids generated only a camel-shape DC on the rough surface regardless of the length of alkyl tail.

A Combined Adaptive Neural Network and Nonlinear Model Predictive Control for Multirate Networked Industrial Process Control.

PubMed

Wang, Tong; Gao, Huijun; Qiu, Jianbin

2016-02-01

This paper investigates the multirate networked industrial process control problem in double-layer architecture. First, the output tracking problem for sampled-data nonlinear plant at device layer with sampling period T(d) is investigated using adaptive neural network (NN) control, and it is shown that the outputs of subsystems at device layer can track the decomposed setpoints. Then, the outputs and inputs of the device layer subsystems are sampled with sampling period T(u) at operation layer to form the index prediction, which is used to predict the overall performance index at lower frequency. Radial basis function NN is utilized as the prediction function due to its approximation ability. Then, considering the dynamics of the overall closed-loop system, nonlinear model predictive control method is proposed to guarantee the system stability and compensate the network-induced delays and packet dropouts. Finally, a continuous stirred tank reactor system is given in the simulation part to demonstrate the effectiveness of the proposed method.

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

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.

Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent.

PubMed

Wissgott, Christian; Schmidt, Wolfram; Brandt-Wunderlich, Christoph; Behrens, Peter; Andresen, Reimer

2017-02-01

To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent's mechanical properties. A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm 2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm 2 ). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

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.

Magnetic and thermodynamic properties of a ferromagnetic mixed-spin (1/2, 1, 3/2) three-layer film superlattice

NASA Astrophysics Data System (ADS)

Lv, Dan; Ma, Ye; Jiang, Wei; Si, Xiu-li; Gao, Wei-chun

2018-07-01

Using the Monte Carlo simulation, we have studied the magnetic and thermodynamic properties of a ferromagnetic three-layer film mixed-spin (1/2, 1, 3/2) system. We have discussed the influence of intralayer and interfacial exchange couplings, film thickness, magnetic atom concentration and temperature on the magnetization of the superlattice system, magnetic susceptibility, internal energy and specific heat of the system. The phase diagrams in various parameters planes are obtained. Loads of interesting magnetic behaviors have been found, such as double-peak and triple-peak phenomena in the susceptibility and specific heat curves as well as obvious finite size effects for small layer thickness. Through a comparison, there is qualitatively a good agreement between our results and those of other theoretical and experimental studies.

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.

Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective.

PubMed

Abellán, Gonzalo; Martí-Gastaldo, Carlos; Ribera, Antonio; Coronado, Eugenio

2015-06-16

Design of functional hybrids lies at the very core of synthetic chemistry as it has enabled the development of an unlimited number of solids displaying unprecedented or even improved properties built upon the association at the molecular level of quite disparate components by chemical design. Multifunctional hybrids are a particularly appealing case among hybrid organic/inorganic materials. Here, chemical knowledge is used to deploy molecular components bearing different functionalities within a single solid so that these properties can coexist or event interact leading to unprecedented phenomena. From a molecular perspective, this can be done either by controlled assembly of organic/inorganic molecular tectons into an extended architecture of hybrid nature or by intercalation of organic moieties within the empty channels or interlamellar space offered by inorganic solids with three-dimensional (MOFs, zeolites, and mesoporous hosts) or layered structures (phosphates, silicates, metal dichalcogenides, or anionic clays). This Account specifically illustrates the use of layered double hydroxides (LDHs) in the preparation of magnetic hybrids, in line with the development of soft inorganic chemistry processes (also called "Chimie Douce"), which has significantly contributed to boost the preparation hybrid materials based on solid-state hosts and subsequent development of applications. Several features sustain the importance of LDHs in this context. Their magnetism can be manipulated at a molecular level by adequate choice of constituting metals and interlayer separation for tuning the nature and extent of magnetic interactions across and between planes. They display unparalleled versatility in accommodating a broad range of anionic species in their interlamellar space that encompasses not only simple anions but chemical systems of increasing dimensionality and functionalities. Their swelling characteristics allow for their exfoliation in organic solvents with high dielectric strength, to produce two-dimensional nanosheets with atomic thickness that can be used as macromolecular building blocks in the assembly of nanocomposites. We describe how these advantageous properties turn LDHs into excellent vehicles for the preparation of multifunctional materials with increasing levels of complexity. For clarity, the reader will first find a succinct description of the most relevant aspects controlling the magnetism of LDHs followed by their use in the preparation of magnetic hybrids from a molecular perspective. This includes the intercalation anionic species of increasing nuclearity like paramagnetic mononuclear complexes, stimulus-responsive molecular guests, one- and two-dimensional coordination polymers, or even preassembled 2D networks. This approach allows us to evolve from "dual-function" materials with coexistence, for example, of magnetism and superconductivity, to smart materials in which the magnetic or structural properties of the LDH layers can be tuned by applying an external stimulus like light or temperature. We will conclude with a brief look into the promising features offered by magnetic nanocomposites based on LDHs and our views on the most promising directions to be pursued in this context.

Streaming potential method for characterizing interaction of electrical double layers between rice roots and Fe/Al oxide-coated quartz in situ.

PubMed

Liu, Zhao-Dong; Wang, Hai-Cui; Li, Jiu-Yu; Xu, Ren-Kou

2017-10-01

The interaction between rice roots and Fe/Al oxide-coated quartz was investigated through zeta potential measurements and column leaching experiments in present study. The zeta potentials of rice roots, Fe/Al oxide-coated quartz, and the binary systems containing rice roots and Fe/Al oxide-coated quartz were measured by a specially constructed streaming potential apparatus. The interactions between rice roots and Fe/Al oxide-coated quartz particles were evaluated/deduced based on the differences of zeta potentials between the binary systems and the single system of rice roots. The zeta potentials of the binary systems moved in positive directions compared with that of rice roots, suggesting that there were overlapping of diffuse layers of electric double layers on positively charged Fe/Al oxide-coated quartz and negatively charged rice roots and neutralization of positive charge on Fe/Al oxide-coated quartz with negative charge on rice roots. The greater amount of positive charges on Al oxide led to the stronger interaction of Al oxide-coated quartz with rice roots and the more shift of zeta potential compared with Fe oxide. The overlapping of diffuse layers on Fe/Al oxide-coated quartz and rice roots was confirmed by column leaching experiments. The greater overlapping of diffuse layers on Al oxide and rice roots led to more simultaneous adsorptions of K + and NO 3 - and greater reduction in leachate electric conductivity when the column containing Al oxide-coated quartz and rice roots was leached with KNO 3 solution, compared with the columns containing rice roots and Fe oxide-coated quartz or quartz. When the KNO 3 solution was replaced with deionized water to flush the columns, more K + and NO 3 - were desorbed from the binary system containing Al oxide-coated quartz and rice roots than from other two binary systems, suggesting that the stronger electrostatic interaction between Al oxide and rice roots promoted the desorption of K + and NO 3 - from the binary system and enhanced overlapping of diffuse layers on these oppositely charged surfaces compared with other two binary systems. In conclusion, the overlapping of diffuse layers occurred between positively charged Fe/Al oxides and rice roots, which led to neutralization of opposite charge and affected adsorption and desorption of ions onto and from the charged surfaces of Fe/Al oxides and rice roots.

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

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.

Biotransformation in Double-Phase Systems: Physiological Responses of Pseudomonas putida DOT-T1E to a Double Phase Made of Aliphatic Alcohols and Biosynthesis of Substituted Catechols

PubMed Central

Rojas, Antonia; Duque, Estrella; Schmid, Andreas; Hurtado, Ana; Ramos, Juan-Luis; Segura, Ana

2004-01-01

Pseudomonas putida strain DOT-T1E is highly tolerant to organic solvents, with a logPow (the logarithm of the partition coefficient of a solvent in a two-phase water-octanol system of ≥2.5. Solvent tolerant microorganisms can be exploited to develop double-phase (organic solvent and water) biotransformation systems in which toxic substrates or products are kept in the organic phase. We tested P. putida DOT-T1E tolerance to different aliphatic alcohols with a logPow value between 2 and 4, such as decanol, nonanol, and octanol, which are potentially useful in biotransformations in double-phase systems in which compounds with a logPow around 1.5 are produced. P. putida DOT-T1E responds to aliphatic alcohols as the second phase through cis-to-trans isomerization of unsaturated cis fatty acids and through efflux of these aliphatic alcohols via a series of pumps that also extrude aromatic hydrocarbons. These defense mechanisms allow P. putida DOT-T1E to survive well in the presence of high concentrations of the aliphatic alcohols, and growth with nonanol or decanol occurred at a high rate, whereas in the presence of an octanol double-phase growth was compromised. Our results support that the logPow of aliphatic alcohols correlates with their toxic effects, as octanol (logPow = 2.9) has more negative effects in P. putida cells than 1-nonanol (logPow = 3.4) or 1-decanol (logPow = 4). A P. putida DOT-T1E derivative bearing plasmid pWW0-xylE::Km transforms m-xylene (logPow = 3.2) into 3-methylcatechol (logPow = 1.8). The amount of 3-methylcatechol produced in an aliphatic alcohol/water bioreactor was 10- to 20-fold higher than in an aqueous medium, demonstrating the usefulness of double-phase systems for this particular biotransformation. PMID:15184168

Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).

PubMed

Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

2012-04-01

TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure.

Effect of CaCl2 on the property of an anionic surfactant monolayer formed at the air/water interface: a molecular dynamics study

NASA Astrophysics Data System (ADS)

Zhang, Tiantian; You, Jing; Yu, Jiliang; Fan, Chengcheng; Ma, Yunfei; Cui, Yanjie; Gao, Shanshan; Li, Yongbin; Hu, Songqing; Liu, Huiqin

2017-12-01

Molecular dynamics simulation had been carried out to investigate the influence of CaCl2 on the aggregation behaviour of sodium dodecyl polyoxyethylene sulfonate (A12E2SO3) at the air/water interface. First, structure properties of A12E2SO3 monolayer was studied by analyzing the snapshots of the configuration and density profiles of different components in A12E2SO3 systems. Results showed that Ca2+ could replace some Na+ to combine with the hydrophilic headgroups. Besides, the addition of CaCl2 could reduce the thickness of water layer at the interface. Second, the interactions between A12E2SO3 headgroups and water molecules were studied through calculating radial distribution functions (RDFs) between water molecules and the sulfonate group, as well as the oxyethyl group. Results revealed that Ca2+ could penetrate the hydration layer of the sulfonate group, but could not enter the first hydration layer of the oxygen ethyl group close to the sulfonate group. The addition of CaCl2 could make the degree of hydration more orderly and the thickness of hydration layer in the headgroups of A12E2SO3 molecules increase. Third, the property of interface double layer was studied through analyzing RDFs of the headgroups and counterions. Results showed that the addition of CaCl2 could not only reduce the interaction between the headgroups and the counterions, but also compress the thickness of the electric double layer in A12E2SO3 system.

Nanostructured antistatic and antireflective thin films made of indium tin oxide and silica over-coat layer

NASA Astrophysics Data System (ADS)

Cho, Young-Sang; Hong, Jeong-Jin; Yang, Seung-Man; Choi, Chul-Jin

2010-08-01

Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

Solution pH change in non-uniform alternating current electric fields at frequencies above the electrode charging frequency

PubMed Central

An, Ran; Massa, Katherine

2014-01-01

AC Faradaic reactions have been reported as a mechanism inducing non-ideal phenomena such as flow reversal and cell deformation in electrokinetic microfluidic systems. Prior published work described experiments in parallel electrode arrays below the electrode charging frequency (fc), the frequency for electrical double layer charging at the electrode. However, 2D spatially non-uniform AC electric fields are required for applications such as in plane AC electroosmosis, AC electrothermal pumps, and dielectrophoresis. Many microscale experimental applications utilize AC frequencies around or above fc. In this work, a pH sensitive fluorescein sodium salt dye was used to detect [H+] as an indicator of Faradaic reactions in aqueous solutions within non-uniform AC electric fields. Comparison experiments with (a) parallel (2D uniform fields) electrodes and (b) organic media were employed to deduce the electrode charging mechanism at 5 kHz (1.5fc). Time dependency analysis illustrated that Faradaic reactions exist above the theoretically predicted electrode charging frequency. Spatial analysis showed [H+] varied spatially due to electric field non-uniformities and local pH changed at length scales greater than 50 μm away from the electrode surface. Thus, non-uniform AC fields yielded spatially varied pH gradients as a direct consequence of ion path length differences while uniform fields did not yield pH gradients; the latter is consistent with prior published data. Frequency dependence was examined from 5 kHz to 12 kHz at 5.5 Vpp potential, and voltage dependency was explored from 3.5 to 7.5 Vpp at 5 kHz. Results suggest that Faradaic reactions can still proceed within electrochemical systems in the absence of well-established electrical double layers. This work also illustrates that in microfluidic systems, spatial medium variations must be considered as a function of experiment time, initial medium conditions, electric signal potential, frequency, and spatial position. PMID:25553200

A novel antiproliferative drug coating for glaucoma drainage devices.

PubMed

Ponnusamy, Thiruselvam; Yu, Haini; John, Vijay T; Ayyala, Ramesh S; Blake, Diane A

2014-01-01

The implantation of a glaucoma drainage device (GDD) is often necessary for intractable cases of glaucoma. Currently, the success rate of GDD implants is relatively low because fibrosis that develops during the wound-healing process ultimately blocks fluid drainage. We describe herein a novel porous coating for Ahmed glaucoma valves based on biodegradable poly(lactic-co-glycolic acid) (PLGA). Thin films of PLGA were fabricated using a spin-coating technique. The procedure led to an asymmetric pore structure that was exploited to control the rate of dissolution. Double-layered porous films were constructed to achieve continuous drug release. A cell culture system was used to test the efficacy of these coatings. Double-layered films were manufactured to provide a burst of mitomycin C (MMC) release followed by a slow release of 5-fluorouracil (5-FU), which together prevented fibrosis over the most active period of postoperative wound healing (0 to 28 d). Double-layered films containing 5-FU only in the bottom layer showed a 3- to 5-day delay in drug release, followed by a sharp increase that continued for ~28 days. MMC was stable only when surface-loaded, and this drug was therefore surface-loaded onto the top PLGA layer to provide a continuous release of antifibrotics over the wound-healing period. The combined use of both MMC and 5-FU in a biodegradable device inhibits cell proliferation in a tissue culture model and has the potential to reduce fibrosis and increase the success rate of GDD implants. The design is simple and can be scaled for commercial production.

Atomistic Molecular Dynamics Simulations of the Electrical Double

NASA Astrophysics Data System (ADS)

Li, Zifeng; Milner, Scott; Fichthorn, Kristen

2015-03-01

The electrical double layer (EDL) near the polymer/water interface plays a key role in the colloidal stability of latex paint. To elucidate the structure of the EDL at the molecular level, we conducted an all-atom molecular dynamics simulations. We studied two representative surface charge groups in latex, the ionic surfactant sodium dodecyl sulfate (SDS) and the grafted short polyelectrolyte charged by dissociated methyl methacrylic acid (MAA) monomers. Our results confirm that the Poisson-Boltzmann theory works well outside the Stern layer. Our calculated electrostatic potential at the Outer Helmholtz Plane (OHP) is close to the zeta potential measured experimentally, which suggests that the potential at the OHP is a good estimate of the zeta potential. We found that the position of the OHP for the MAA polyelectrolyte system extends much further into the aqueous phase than that in the SDS system, resulting in a Stern layer that is twice as thick. This model will allow for future investigations of the interactions of the surface with different surfactants and rheology modifiers, which may serve as a guide to tune the rheology of latex formulations. We thank Dow Chemical Company for financial support.

Current situation and control measures of groundwater pollution in gas station

NASA Astrophysics Data System (ADS)

Wu, Qiong; Zhang, Xiaofeng; Zhang, Qianjin

2017-11-01

In recent years, pollution accidents caused by gas station leakage has occurred worldwide which can be persistent in groundwater. Numerous studies have demonstrated that the contaminated groundwater is threatening the ecological environment and human health. In this article, current status and sources of groundwater pollution by gas station are analyzed, and experience of how to prevent groundwater pollution from gas stations are summarized. It is demonstrated that installation of secondary containment measures for the oil storage of the oil tank system, such as installation of double-layer oil tanks or construction of impermeable ponds, is a preferable method to prevent gas stations from groundwater pollution. Regarding to the problems of groundwater pollution caused by gas station, it is proposed that it is urgent to investigate the leakage status of gas station. Relevant precise implementation regulations shall be issued and carried out, and supervision management of gas stations would need to be strengthened. Then single-layer steel oil tanks shall be replaced by double-layer tanks, and the impermeable ponds should be constructed according to the risk ranking. From the control methodology, the groundwater environment monitoring systems, supervision level, laws and regulations as well as pollution remediation should also be carried out and strengthened.

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

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

Oscillatory double-diffusive convection (ODDC, more traditionally called semiconvection) is a form of linear double-diffusive instability that occurs in fluids that are unstably stratified in temperature (Schwarzschild unstable), but stably stratified in chemical composition (Ledoux stable). This scenario is thought to be quite common in the interiors of stars and giant planets, and understanding the transport of heat and chemical species by ODDC is of great importance to stellar and planetary evolution models. Fluids unstable to ODDC have a tendency to form convective thermocompositional layers that significantly enhance the fluxes of temperature and chemical composition compared with microscopic diffusion. Although a numbermore » of recent studies have focused on studying properties of both layered and nonlayered ODDC, few have addressed how additional physical processes such as global rotation affect its dynamics. In this work, we study first how rotation affects the linear stability properties of rotating ODDC. Using direct numerical simulations, we then analyze the effect of rotation on properties of layered and nonlayered ODDC, and we study how the angle of the rotation axis with respect to the direction of gravity affects layering. We find that rotating systems can be broadly grouped into two categories based on the strength of rotation. The qualitative behavior in the more weakly rotating group is similar to nonrotating ODDC, but strongly rotating systems become dominated by vortices that are invariant in the direction of the rotation vector and strongly influence transport. We find that whenever layers form, rotation always acts to reduce thermal and compositional transport.« less

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.

Two-photon excited autofluorescence imaging of freshly isolated frog retinas.

PubMed

Lu, Rong-Wen; Li, Yi-Chao; Ye, Tong; Strang, Christianne; Keyser, Kent; Curcio, Christine A; Yao, Xin-Cheng

2011-06-01

The purpose of this study was to investigate cellular sources of autofluorescence signals in freshly isolated frog (Rana pipiens) retinas. Equipped with an ultrafast laser, a laser scanning two-photon excitation fluorescence microscope was employed for sub-cellular resolution examination of both sliced and flat-mounted retinas. Two-photon imaging of retinal slices revealed autofluorescence signals over multiple functional layers, including the photoreceptor layer (PRL), outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer (IPL), and ganglion cell layer (GCL). Using flat-mounted retinas, depth-resolved imaging of individual retinal layers further confirmed multiple sources of autofluorescence signals. Cellular structures were clearly observed at the PRL, ONL, INL, and GCL. At the PRL, the autofluorescence was dominantly recorded from the intracellular compartment of the photoreceptors; while mixed intracellular and extracellular autofluorescence signals were observed at the ONL, INL, and GCL. High resolution autofluorescence imaging clearly revealed mosaic organization of rod and cone photoreceptors; and sub-cellular bright autofluorescence spots, which might relate to connecting cilium, was observed in the cone photoreceptors only. Moreover, single-cone and double-cone outer segments could be directly differentiated.

New Approach for High-Voltage Electrical Double-Layer Capacitors Using Vertical Graphene Nanowalls with and without Nitrogen Doping.

PubMed

Chi, Yu-Wen; Hu, Chi-Chang; Shen, Hsiao-Hsuan; Huang, Kun-Ping

2016-09-14

Integrating various devices to achieve high-performance energy storage systems to satisfy various demands in modern societies become more and more important. Electrical double-layer capacitors (EDLCs), one kind of the electrochemical capacitors, generally provide the merits of high charge-discharge rates, extremely long cycle life, and high efficiency in electricity capture/storage, leading to a desirable device of electricity management from portable electronics to hybrid vehicles or even smart grid application. However, the low cell voltage (2.5-2.7 V in organic liquid electrolytes) of EDLCs lacks the direct combination of Li-ion batteries (LIBs) and EDLCs for creating new functions in future applications without considering the issue of a relatively low energy density. Here we propose a guideline, "choosing a matching pair of electrode materials and electrolytes", to effectively extend the cell voltage of EDLCs according to three general strategies. Based on the new strategy proposed in this work, materials with an inert surface enable to tolerate a wider potential window in commercially available organic electrolytes in comparison with activated carbons (ACs). The binder-free, vertically grown graphene nanowalls (GNW) and nitrogen-doped GNW (NGNW) electrodes respectively provide good examples for extending the upper potential limit of a positive electrode of EDLCs from 0.1 to 1.5 V (vs Ag/AgNO3) as well as the lower potential limit of a negative electrode of EDLCs from -2.0 V to ca. -2.5 V in 1 M TEABF4/PC (propylene carbonate) compared to ACs. This newly designed asymmetric EDLC exhibits a cell voltage of 4 V, specific energy of 52 Wh kg(-1) (ca. a device energy density of 13 Wh kg(-1)), and specific power of 8 kW kg(-1) and ca. 100% retention after 10,000 cycles charge-discharge, reducing the series number of EDLCs to enlarge the module voltage and opening the possibility for directly combining EDLCs and LIBs in advanced applications.

The multi-layer multi-configuration time-dependent Hartree method for bosons: theory, implementation, and applications.

PubMed

Cao, Lushuai; Krönke, Sven; Vendrell, Oriol; Schmelcher, Peter

2013-10-07

We develop the multi-layer multi-configuration time-dependent Hartree method for bosons (ML-MCTDHB), a variational numerically exact ab initio method for studying the quantum dynamics and stationary properties of general bosonic systems. ML-MCTDHB takes advantage of the permutation symmetry of identical bosons, which allows for investigations of the quantum dynamics from few to many-body systems. Moreover, the multi-layer feature enables ML-MCTDHB to describe mixed bosonic systems consisting of arbitrary many species. Multi-dimensional as well as mixed-dimensional systems can be accurately and efficiently simulated via the multi-layer expansion scheme. We provide a detailed account of the underlying theory and the corresponding implementation. We also demonstrate the superior performance by applying the method to the tunneling dynamics of bosonic ensembles in a one-dimensional double well potential, where a single-species bosonic ensemble of various correlation strengths and a weakly interacting two-species bosonic ensemble are considered.

Mod silver metallization: Screen printing and ink-jet printing

NASA Technical Reports Server (NTRS)

Vest, R. W.; Vest, G. M.

1985-01-01

Basic material efforts have proven to be very successful. Adherent and conductive films were achieved. A silver neodecanoate/bismuth 2-ethylhexanoate mixture has given the best results in both single and double layer applications. Another effort is continuing to examine the feasibility of applying metallo-organic deposition films by use of an ink jet printer. Direct line writing would result in a saving of process time and materials. So far, some well defined lines have been printed.

Fabrication of 3-D nanodimensioned electric double layer capacitor structures using block copolymer templates.

PubMed

Rasappa, Sozaraj; Borah, Dipu; Senthamaraikannan, Ramsankar; Faulkner, Colm C; Holmes, Justin D; Morris, Michael A

2014-07-01

The need for materials for high energy storage has led to very significant research in supercapacitor systems. These can exhibit electrical double layer phenomena and capacitances up to hundreds of F/g. Here, we demonstrate a new supercapacitor fabrication methodology based around the microphase separation of PS-b-PMMA which has been used to prepare copper nanoelectrodes of dimension -13 nm. These structures provide excellent capacitive performance with a maximum specific capacitance of -836 F/g for a current density of 8.06 A/g at a discharge current as high as 75 mA. The excellent performance is due to a high surface area: volume ratio. We suggest that this highly novel, easily fabricated structure might have a number of important applications.

Carbon-Nanotube-Based Electrochemical Double-Layer Capacitor Technologies for Spaceflight Applications

NASA Technical Reports Server (NTRS)

Arepalli, S.; Fireman, H.; Huffman, C.; Maloney, P.; Nikolaev, P.; Yowell, L.; Kim, K.; Kohl, P. A.; Higgins, C. D.; Turano, S. P.

2005-01-01

Electrochemical double-layer capacitors, or supercapacitors, have tremendous potential as high-power energy sources for use in low-weight hybrid systems for space exploration. Electrodes based on single-wall carbon nanotubes (SWCNTs) offer exceptional power and energy performance due to the high surface area, high conductivity, and the ability to functionalize the SWCNTs to optimize capacitor properties. This paper will report on the preparation of electrochemical capacitors incorporating SWCNT electrodes and their performance compared with existing commercial technology. Preliminary results indicate that substantial increases in power and energy density are possible. The effects of nanotube growth and processing methods on electrochemical capacitor performance is also presented. The compatibility of different SWCNTs and electrolytes was studied by varying the type of electrolyte ions that accumulate on the high-surface-area electrodes.

Short-Term Synaptic Plasticity Regulation in Solution-Gated Indium-Gallium-Zinc-Oxide Electric-Double-Layer Transistors.

PubMed

Wan, Chang Jin; Liu, Yang Hui; Zhu, Li Qiang; Feng, Ping; Shi, Yi; Wan, Qing

2016-04-20

In the biological nervous system, synaptic plasticity regulation is based on the modulation of ionic fluxes, and such regulation was regarded as the fundamental mechanism underlying memory and learning. Inspired by such biological strategies, indium-gallium-zinc-oxide (IGZO) electric-double-layer (EDL) transistors gated by aqueous solutions were proposed for synaptic behavior emulations. Short-term synaptic plasticity, such as paired-pulse facilitation, high-pass filtering, and orientation tuning, was experimentally emulated in these EDL transistors. Most importantly, we found that such short-term synaptic plasticity can be effectively regulated by alcohol (ethyl alcohol) and salt (potassium chloride) additives. Our results suggest that solution gated oxide-based EDL transistors could act as the platforms for short-term synaptic plasticity emulation.

Phase portrait analysis of super solitary waves and flat top solutions

NASA Astrophysics Data System (ADS)

Steffy, S. V.; Ghosh, S. S.

2018-06-01

The phase portrait analysis of super solitary waves has revealed a new kind of intermediate solution which defines the boundary between the two types of super solitary waves, viz., Type I and Type II. A Type I super solitary wave is known to be associated with an intermediate double layer while a Type II solution has no such association. The intermediate solution at the boundary has a flat top structure and is called a flat top solitary wave. Its characteristics resemble an amalgamation of a solitary wave and a double layer. It was found that, mathematically, such kinds of structures may emerge due to the presence of an extra nonlinearity. Although they are relatively unfamiliar in the realm of plasma physics, they have much wider applications in other physical systems.

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).

Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

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

Kim, Tae-Hyun; Oh, Jae-Min, E-mail: jaemin.oh@yonsei.ac.kr

2016-01-15

Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, amore » few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV–vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca{sub 1.30}Al(OH){sub 4.6}FA{sub 0.74}·3.33H{sub 2}O and Ca{sub 1.53}Fe(OH){sub 5.06}FA{sub 2.24}·9.94H{sub 2}O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca. - Highlights: • We successfully intercalated FA molecules into Ca-containing LDHs. • Exfoliation-reassembly was proven to be the most effective. • The interaction between LDH and FA were studied by FT-IR and UV–vis spectra. • Thermal stability of FA were enhanced by electrostatic interaction with LDH layers.« less

Tuning the Cavity Size and Chirality of Self-Assembling 3D DNA Crystals

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

Simmons, Chad R.; Zhang, Fei; MacCulloch, Tara

The foundational goal of structural DNA nanotechnology—the field that uses oligonucleotides as a molecular building block for the programmable self-assembly of nanostructured systems—was to use DNA to construct three-dimensional (3D) lattices for solving macromolecular structures. The programmable nature of DNA makes it an ideal system for rationally constructing self-assembled crystals and immobilizing guest molecules in a repeating 3D array through their specific stereospatial interactions with the scaffold. In this work, we have extended a previously described motif (4 × 5) by expanding the structure to a system that links four double-helical layers; we use a central weaving oligonucleotide containing amore » sequence of four six-base repeats (4 × 6), forming a matrix of layers that are organized and dictated by a series of Holliday junctions. In addition, we have assembled mirror image crystals (l-DNA) with the identical sequence that are completely resistant to nucleases. Bromine and selenium derivatives were obtained for the l- and d-DNA forms, respectively, allowing phase determination for both forms and solution of the resulting structures to 3.0 and 3.05 Å resolution. Both right- and left-handed forms crystallized in the trigonal space groups with mirror image 3-fold helical screw axes P32 and P31 for each motif, respectively. The structures reveal a highly organized array of discrete and well-defined cavities that are suitable for hosting guest molecules and allow us to dictate a priori the assembly of guest–DNA conjugates with a specified crystalline hand.« 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.

Epsilon-near-zero modes for tailored light-matter interaction

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

Campione, Salvatore; Liu, Sheng; Benz, Alexander

Epsilon-near-zero (ENZ) modes arising from condensed-matter excitations such as phonons and plasmons are a new path for tailoring light-matter interactions at the nanoscale. Complex spectral shaping can be achieved by creating such modes in nanoscale semiconductor layers and controlling their interaction with multiple, distinct, dipole resonant systems. Examples of this behavior are presented at midinfrared frequencies for ENZ modes that are strongly coupled to metamaterial resonators and simultaneously strongly coupled to semiconductor phonons or quantum-well intersubband transitions (ISTs), resulting in double- and triple-polariton branches in transmission spectra. For the double-polariton branch case, we find that the best strategy to maximizemore » the Rabi splitting is to use a combination of a doped layer supporting an ENZ feature and a layer supporting ISTs, with overlapping ENZ and IST frequencies. As a result, this design flexibility renders this platform attractive for low-voltage tunable filters, light-emitting diodes, and efficient nonlinear composite materials.« less

Epsilon-near-zero modes for tailored light-matter interaction

DOE PAGES

Campione, Salvatore; Liu, Sheng; Benz, Alexander; ...

2015-10-20

Epsilon-near-zero (ENZ) modes arising from condensed-matter excitations such as phonons and plasmons are a new path for tailoring light-matter interactions at the nanoscale. Complex spectral shaping can be achieved by creating such modes in nanoscale semiconductor layers and controlling their interaction with multiple, distinct, dipole resonant systems. Examples of this behavior are presented at midinfrared frequencies for ENZ modes that are strongly coupled to metamaterial resonators and simultaneously strongly coupled to semiconductor phonons or quantum-well intersubband transitions (ISTs), resulting in double- and triple-polariton branches in transmission spectra. For the double-polariton branch case, we find that the best strategy to maximizemore » the Rabi splitting is to use a combination of a doped layer supporting an ENZ feature and a layer supporting ISTs, with overlapping ENZ and IST frequencies. As a result, this design flexibility renders this platform attractive for low-voltage tunable filters, light-emitting diodes, and efficient nonlinear composite materials.« less

Double mutation of cell wall proteins CspB and PBP1a increases secretion of the antibody Fab fragment from Corynebacterium glutamicum

PubMed Central

2014-01-01

Background Among other advantages, recombinant antibody-binding fragments (Fabs) hold great clinical and commercial potential, owing to their efficient tissue penetration compared to that of full-length IgGs. Although production of recombinant Fab using microbial expression systems has been reported, yields of active Fab have not been satisfactory. We recently developed the Corynebacterium glutamicum protein expression system (CORYNEX®) and demonstrated improved yield and purity for some applications, although the system has not been applied to Fab production. Results The Fab fragment of human anti-HER2 was successfully secreted by the CORYNEX® system using the conventional C. glutamicum strain YDK010, but the productivity was very low. To improve the secretion efficiency, we investigated the effects of deleting cell wall-related genes. Fab secretion was increased 5.2 times by deletion of pbp1a, encoding one of the penicillin-binding proteins (PBP1a), mediating cell wall peptidoglycan (PG) synthesis. However, this Δpbp1a mutation did not improve Fab secretion in the wild-type ATCC13869 strain. Because YDK010 carries a mutation in the cspB gene encoding a surface (S)-layer protein, we evaluated the effect of ΔcspB mutation on Fab secretion from ATCC13869. The Δpbp1a mutation showed a positive effect on Fab secretion only in combination with the ΔcspB mutation. The ΔcspBΔpbp1a double mutant showed much greater sensitivity to lysozyme than either single mutant or the wild-type strain, suggesting that these mutations reduced cell wall resistance to protein secretion. Conclusion There are at least two crucial permeability barriers to Fab secretion in the cell surface structure of C. glutamicum, the PG layer, and the S-layer. The ΔcspBΔpbp1a double mutant allows efficient Fab production using the CORYNEX® system. PMID:24731213

Performance of Multi Walled Carbon Nanotubes Grown on Conductive Substrates as Supercapacitors Electrodes using Organic and Ionic liquid electrolytes

NASA Astrophysics Data System (ADS)

Winchester, Andrew; Ghosh, Sujoy; Turner, Ben; Zhang, X. F.; Talapatra, Saikat

2012-02-01

In this work we will present the use of Multi Walled Carbon Nanotubes (MWNT) directly grown on inconel substrates via chemical vapor deposition, as electrode materials for electrochemical double layer capacitors (EDLC). The performance of the MWNT EDLC electrodes were investigated using two electrolytes, an organic electrolyte, tetraethylammonium tetrafluoroborate in propylene carbonate (Et4NBF4 in PC), and a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements to obtain values for the capacitance and internal resistance of these devices will be presented and compared.

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

A new type of high energy asymmetric capacitor with nanoporous carbon electrodes in aqueous electrolyte

NASA Astrophysics Data System (ADS)

Khomenko, V.; Raymundo-Piñero, E.; Béguin, F.

A new type of low cost and high energy asymmetric capacitor based on only activated carbons for both electrodes has been developed in a safe and environment friendly aqueous electrolyte. In such electrolyte, the charges are stored in the electrical double-layer and through fast faradaic charge transfer processes. By taking profit of different redox reactions occurring in the positive and negative ranges of potential, it is possible to optimize the capacitor either by balancing the mass of the electrodes or by using different optimized carbons for the positive and negative electrodes. The best results are obtained in the latter case, by utilizing different pseudo-faradaic properties of carbons in order to increase the capacitance and to shift the potentials of water decomposition and destructive oxidation of activated carbon to more negative and positive values, respectively. After an additional adjustment of potentials by mass-balancing the two electrodes, the electrochemical capacitor can be reversibly charged/discharged at 1.6 V in aqueous medium, with energy densities close to the values obtained with electrical double-layer capacitors working in organic electrolytes, while avoiding their disadvantages.

"Egg-Box"-Assisted Fabrication of Porous Carbon with Small Mesopores for High-Rate Electric Double Layer Capacitors.

PubMed

Kang, Danmiao; Liu, Qinglei; Gu, Jiajun; Su, Yishi; Zhang, Wang; Zhang, Di

2015-11-24

Here we report a method to fabricate porous carbon with small mesopores around 2-4 nm by simple activation of charcoals derived from carbonization of seaweed consisting of microcrystalline domains formed by the "egg-box" model. The existence of mesopores in charcoals leads to a high specific surface area up to 3270 m(2) g(-1), with 95% surface area provided by small mesopores. This special pore structure shows high adaptability when used as electrode materials for an electric double layer capacitor, especially at high charge-discharge rate. The gravimetric capacitance values of the porous carbon are 425 and 210 F g(-1) and volumetric capacitance values are 242 and 120 F cm(-3) in 1 M H2SO4 and 1 M TEA BF4/AN, respectively. The capacitances even remain at 280 F g(-1) (160 F cm(-3)) at 100 A g(-1) and 156 F g(-1) (90 F cm(-3)) at 50 A g(-1) in the aqueous and organic electrolytes, demonstrating excellent high-rate capacitive performance.

A multiphase ion-transport analysis of the electrostatic disjoining pressure: implications for binary droplet coalescence

NASA Astrophysics Data System (ADS)

Mason, Lachlan; Gebauer, Felix; Bart, Hans-Jörg; Stevens, Geoffrey; Harvie, Dalton

2016-11-01

Understanding the physics of emulsion coalescence is critical for the robust simulation of industrial solvent extraction processes, in which loaded organic and raffinate phases are separated via the coalescence of dispersed droplets. At the droplet scale, predictive collision-outcome models require an accurate description of the repulsive surface forces arising from electrical-double-layer interactions. The conventional disjoining-pressure treatment of double-layer forces, however, relies on assumptions which do not hold generally for deformable droplet collisions: namely, low interfacial curvature and negligible advection of ion species. This study investigates the validity bounds of the disjoining pressure approximation for low-inertia droplet interactions. A multiphase ion-transport model, based on a coupling of droplet-scale Nernst-Planck and Navier-Stokes equations, predicts ion-concentration fields that are consistent with the equilibrium Boltzmann distribution; indicating that the disjoining-pressure approach is valid for both static and dynamic interactions in low-Reynolds-number settings. The present findings support the development of coalescence kernels for application in macro-scale population balance modelling.

Synthesis and characterization of Zn-Ti layered double hydroxide intercalated with cinnamic acid for cosmetic application

NASA Astrophysics Data System (ADS)

Li, Yong; Tang, Liping; Ma, Xinxu; Wang, Xinrui; Zhou, Wei; Bai, Dongsheng

2017-08-01

The use of sunscreen is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently. In this work, an organic ultraviolet (UV) ray absorbent, cinnamic acid (CA) was intercalated into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. ZnTi-CA-LDH, a new type of host-guest UV-blocking material has been synthesized. Detailed structural and surface morphology of ZnTi-CA-LDH were characterized by XRD, FT-IR, SEM and TEM. ZnTi-CA-LDH exhibits a superior UV blocking ability compared to pure CA and ZnTi-CO3-LDH. The thermal stability of the intercalated ZnTi-CA-LDH was investigated by TG-DTA, which showed that the thermostability of CA was markedly enhanced after intercalation into ZnTi-CO3-LDH. The EPR data showed greatly decreased photocatalytic activity compared to common inorganic UV blocking agents TiO2 and ZnO. Furthermore, the sample was formulated in a sunscreen cream to study the matrix protective effect towards UV rays.

One-step synthesis of layered yttrium hydroxides in immiscible liquid-liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

NASA Astrophysics Data System (ADS)

Watanabe, Mebae; Fujihara, Shinobu

2014-02-01

Inorganic-organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid-liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu3+ ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect.

Designed synthesis of double-stage two-dimensional covalent organic frameworks

PubMed Central

Chen, Xiong; Addicoat, Matthew; Jin, Enquan; Xu, Hong; Hayashi, Taku; Xu, Fei; Huang, Ning; Irle, Stephan; Jiang, Donglin

2015-01-01

Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers in which organic building blocks are covalently and topologically linked to form extended crystalline polygon structures, constituting a new platform for designing π-electronic porous materials. However, COFs are currently synthesised by a few chemical reactions, limiting the access to and exploration of new structures and properties. The development of new reaction systems that avoid such limitations to expand structural diversity is highly desired. Here we report that COFs can be synthesised via a double-stage connection that polymerises various different building blocks into crystalline polygon architectures, leading to the development of a new type of COFs with enhanced structural complexity and diversity. We show that the double-stage approach not only controls the sequence of building blocks but also allows fine engineering of pore size and shape. This strategy is widely applicable to different polymerisation systems to yield hexagonal, tetragonal and rhombus COFs with predesigned pores and π-arrays. PMID:26456081

Designed synthesis of double-stage two-dimensional covalent organic frameworks

NASA Astrophysics Data System (ADS)

Chen, Xiong; Addicoat, Matthew; Jin, Enquan; Xu, Hong; Hayashi, Taku; Xu, Fei; Huang, Ning; Irle, Stephan; Jiang, Donglin

2015-10-01

Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers in which organic building blocks are covalently and topologically linked to form extended crystalline polygon structures, constituting a new platform for designing π-electronic porous materials. However, COFs are currently synthesised by a few chemical reactions, limiting the access to and exploration of new structures and properties. The development of new reaction systems that avoid such limitations to expand structural diversity is highly desired. Here we report that COFs can be synthesised via a double-stage connection that polymerises various different building blocks into crystalline polygon architectures, leading to the development of a new type of COFs with enhanced structural complexity and diversity. We show that the double-stage approach not only controls the sequence of building blocks but also allows fine engineering of pore size and shape. This strategy is widely applicable to different polymerisation systems to yield hexagonal, tetragonal and rhombus COFs with predesigned pores and π-arrays.

Dark current of organic heterostructure devices with insulating spacer layers

NASA Astrophysics Data System (ADS)

Yin, Sun; Nie, Wanyi; Mohite, Aditya D.; Saxena, Avadh; Smith, Darryl L.; Ruden, P. Paul

2015-03-01

The dark current density at fixed voltage bias in donor/acceptor organic planar heterostructure devices can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of an interfacial exciplex state. If the exciplex formation rate limits current flow, the insulating interface layer can increase dark current whereas, if the exciplex recombination rate limits current flow, the insulating interface layer decreases dark current. We present a device model to describe this behavior and illustrate it experimentally for various donor/acceptor systems, e.g. P3HT/LiF/C60.

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…

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.

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.

Improved sensitivity via layered-double-hydroxide-uniformity-dependent chemiluminescence.

PubMed

Li, Zenghe; Wang, Dan; Yuan, Zhiqin; Lu, Chao

2016-12-01

In the last two decades nanoparticles have been widely applied to enhance chemiluminescence (CL). The morphology of nanoparticles has an important influence on nanoparticle-amplified CL. However, studies of nanoparticle-amplified CL focus mainly on the size and shape effects, and no attempt has been made to explore the influence of uniformity in nanoparticle-amplified CL processes. In this study we have investigated nanoparticle uniformity in the luminol-H 2 O 2 CL system using layered double hydroxides (LDHs) as a model material. The results demonstrated that the uniformity of LDHs played a key role in CL amplification. A possible mechanism is that LDHs with high uniformity possess abundant catalytic active sites, which results in high CL intensity. Meanwhile, the sensitivity for H 2 O 2 detection was increased by one order of magnitude (1.0 nM). Moreover, the uniform-LDH-amplified luminol CL could be applied to selective detection of glucose in human plasma samples. Furthermore, such a uniformity-dependent CL enhancement effect could adapted to other redox CL systems-for example, the peroxynitrous acid (ONOOH) CL system.

Probing the electrochemical double layer of an ionic liquid using voltammetry and impedance spectroscopy: a comparative study of carbon nanotube and glassy carbon electrodes in [EMIM](+)[EtSO(4)](-).

PubMed

Zheng, J P; Goonetilleke, P C; Pettit, C M; Roy, D

2010-05-15

Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are compared as techniques for analyzing double layer capacitances of ionic liquids (ILs) at the surfaces of two carbon-based electrodes. These systems are relevant for energy storage supercapacitors and often are associated with unconventional electrochemical properties. Certain theoretical and experimental aspects of CV and EIS necessary for quantitative evaluation of the capacitance characteristics of such systems are explored. The experiments use 1-ethyl-3-methyl imidazolium ethylsulfate as a model IL electrolyte in combination with a porous electrode of carbon nanotubes (CNTs). The results are compared with those obtained with a nonporous glassy carbon (GC) electrode. The time is constant, and hence the power delivery characteristics of the experimental cell are affected by the electrolyte resistance and residual faradaic reactions of the IL, as well as by the spatially inhomogeneous electrode surfaces. It is shown that adequate characterization of these IL-electrode systems can be achieved by combining CV with EIS. A phenomenological framework for utilizing this combination is discussed.

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.

Investigation of surface charge density on solid-liquid interfaces by modulating the electrical double layer.

PubMed

Moon, Jong Kyun; Song, Myung Won; Pak, Hyuk Kyu

2015-05-20

A solid surface in contact with water or aqueous solution usually carries specific electric charges. These surface charges attract counter ions from the liquid side. Since the geometry of opposite charge distribution parallel to the solid-liquid interface is similar to that of a capacitor, it is called an electrical double layer capacitor (EDLC). Therefore, there is an electrical potential difference across an EDLC in equilibrium. When a liquid bridge is formed between two conducting plates, the system behaves as two serially connected EDLCs. In this work, we propose a new method for investigating the surface charge density on solid-liquid interfaces. By mechanically modulating the electrical double layers and simultaneously applying a dc bias voltage across the plates, an ac electric current can be generated. By measuring the voltage drop across a load resistor as a function of bias voltage, we can study the surface charge density on solid-liquid interfaces. Our experimental results agree very well with the simple equivalent electrical circuit model proposed here. Furthermore, using this method, one can determine the polarity of the adsorbed state on the solid surface depending on the material used. We expect this method to aid in the study of electrical phenomena on solid-liquid interfaces.

New magnetic rails with double-layer Halbach structure by employing NdFeB and ferrite magnets for HTS maglev

NASA Astrophysics Data System (ADS)

Sun, Ruixue; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Jipeng; Deng, Zigang

2018-01-01

In the high temperature superconducting (HTS) maglev system, the magnetic rail as an essential infrastructure is needed all along the route to carry passengers and goods to the destinations. Thus, large amount of rare earth magnetic materials are required in the magnetic rail construction. In order to decrease the dependence of magnetic rails on rare earth elements, the ferrite magnet is employed to replace part of the NdFeB magnets containing rare earth elements. Consequently, a new type rail with double-layer Halbach structure is presented, which is consisted of NdFeB and ferrite magnets. In this paper, we designed and fabricated the proposed rail, and further measured its magnetic flux density distribution and electromagnetic force interacting with HTS bulks. Experimental results indicate that, this new type rail, in double-layer Halbach structure, can achieve an equivalent distribution of magnetic flux density and levitation performance as the pure NdFeB Halbach rail, while a 10% reduction in NdFeB magnet consumption can be realized at the same time. In addition this work explores another magnetic material selection for HTS maglev applications. The dependence on rare earth element and the cost of magnetic rails can be further reduced, as the coercive force of ferrite magnets improved.

Nanoscale Roughness and Morphology Affect the IsoElectric Point of Titania Surfaces

PubMed Central

Borghi, Francesca; Vyas, Varun; Podestà, Alessandro; Milani, Paolo

2013-01-01

We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2) surfaces in aqueous solutions. IsoElectric Points (IEPs) of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces. PMID:23874708

Evaluation of layered and mixed passive treatment systems for acid mine drainage.

PubMed

Jeen, Sung-Wook; Mattson, Bruce

2016-11-01

Laboratory column tests for passive treatment systems for mine drainage from a waste rock storage area were conducted to evaluate suitable reactive mixture, system configuration, effects of influent water chemistry, and required residence time. Five columns containing straw, chicken manure, mushroom compost, and limestone (LS), in either layered or mixed configurations, were set up to simulate the treatment system. The results showed that all of the five columns removed metals of concern (i.e. Al, Cd, Co, Cu, Fe, Ni, and Zn) with a residence time of 15 h and greater. Reaction mechanisms responsible for the removal of metals may include sulfate reduction and subsequent sulfide precipitation, precipitation of secondary carbonates and hydroxides, co-precipitation, and sorption on organic substrates and secondary precipitates. The results suggest that the mixed systems containing organic materials and LS perform better than the layered systems, sequentially treated by organic and LS layers, due to the enhanced pH adjustment, which is beneficial to bacterial activity and precipitation of secondary minerals. The column tests provide a basis for the design of a field-scale passive treatment system, such as a reducing and alkalinity producing system or a permeable reactive barrier.

Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System: Modeling Ion Outflow

NASA Astrophysics Data System (ADS)

Schunk, R. W.; Barakat, A. R.; Eccles, V.; Karimabadi, H.; Omelchenko, Y.; Khazanov, G. V.; Glocer, A.; Kistler, L. M.

2014-12-01

A Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System is being developed in order to provide a rigorous approach to modeling the interaction of hot and cold particle interactions. The framework will include ion and electron kinetic species in the ionosphere, plasmasphere and polar wind, and kinetic ion, super-thermal electron and fluid electron species in the magnetosphere. The framework is ideally suited to modeling ion outflow from the ionosphere and plasmasphere, where a wide range for fluid and kinetic processes are important. These include escaping ion interactions with (1) photoelectrons, (2) cusp/auroral waves, double layers, and field-aligned currents, (3) double layers in the polar cap due to the interaction of cold ionospheric and hot magnetospheric electrons, (4) counter-streaming ions, and (5) electromagnetic wave turbulence. The kinetic ion interactions are particularly strong during geomagnetic storms and substorms. The presentation will provide a brief description of the models involved and discuss the effect that kinetic processes have on the ion outflow.

Magneto-transport of an electron bilayer system in an undoped Si/SiGe double-quantum-well heterostructure

DOE PAGES

Laroche, Dominique; Huang, ShiHsien; Nielsen, Erik; ...

2015-04-08

We report the design, the fabrication, and the magneto-transport study of an electron bilayer system embedded in an undoped Si/SiGe double-quantum-well heterostructure. Additionally, the combined Hall densities (n Hall ) ranging from 2.6 × 10 10 cm -2 to 2.7 × 10 11 cm -2 were achieved, yielding a maximal combined Hall mobility (μ Hall ) of 7.7 × 10 5 cm 2/(V • s) at the highest density. Simultaneous electron population of both quantum wells is clearly observed through a Hall mobility drop as the Hall density is increased to n Hall > 3.3 × 10 10 cm -2,more » consistent with Schrödinger-Poisson simulations. Furthermore, the integer and fractional quantum Hall effects are observed in the device, and single-layer behavior is observed when both layers have comparable densities, either due to spontaneous interlayer coherence or to the symmetric-antisymmetric gap.« less

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.

Self-Template-Directed Metal-Organic Frameworks Network and the Derived Honeycomb-Like Carbon Flakes via Confinement Pyrolysis.

PubMed

Wang, Jie; Tang, Jing; Ding, Bing; Chang, Zhi; Hao, Xiaodong; Takei, Toshiaki; Kobayashi, Naoya; Bando, Yoshio; Zhang, Xiaogang; Yamauchi, Yusuke

2018-04-01

Metal-organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self-template strategy is developed to prepare MOF networks. In this work, layered double-metal hydroxide (LDH) and other layered metal hydroxides are used not only as a scaffold but also as a self-sacrificed metal source. After capturing the abundant metal cations identically from the LDH by the organic linkers, MOF networks are in situ formed. It is interesting that the MOF network-derived carbon materials retain the flake morphology and exhibit a unique honeycomb-like macroporous structure due to the confined shrinkage of the polyhedral facets. The overall properties of the carbon networks are adjustable according to the tailored metal compositions in LDH and the derived MOFs, which are desirable for target-oriented applications as exemplified by the electrochemical application in supercapacitors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal–Organic Nanosheets Formed via Defect-Mediated Transformation of a Hafnium Metal–Organic Framework

PubMed Central

2017-01-01

We report a hafnium-containing MOF, hcp UiO-67(Hf), which is a ligand-deficient layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its lower ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed “double cluster” (Hf12O8(OH)14), analogous to the condensation of coordination polyhedra in oxide frameworks. In oxide frameworks, variable stoichiometry can lead to more complex defect structures, e.g., crystallographic shear planes or modules with differing compositions, which can be the source of further chemical reactivity; likewise, the layered hcp UiO-67 can react further to reversibly form a two-dimensional metal–organic framework, hxl UiO-67. Both three-dimensional hcp UiO-67 and two-dimensional hxl UiO-67 can be delaminated to form metal–organic nanosheets. Delamination of hcp UiO-67 occurs through the cleavage of strong hafnium-carboxylate bonds and is effected under mild conditions, suggesting that defect-ordered MOFs could be a productive route to porous two-dimensional materials. PMID:28343394

The Electronic and Optical Properties of Au Doped Single-Layer Phosphorene

NASA Astrophysics Data System (ADS)

Zhu, Ziqing; Chen, Changpeng; Liu, Jiayi; Han, Lu

2018-01-01

The electronic properties and optical properties of single and double Au-doped phosphorene have been comparatively investigated using the first-principles plane-wave pseudopotential method based on density functional theory. The decrease from direct band gap 0.78 eV to indirect band gap 0.22 and 0.11 eV are observed in the single and double Au-doped phosphorene, respectively. The red shifts of absorbing edge occur in both doped systems, which consequently enhance the absorbing of infrared light in phosphorene. Band gap engineering can, therefore, be used to directly tune the optical absorption of phosphorene system by substitutional Au doping.

Thermal Properties of Double-Aluminized Kapton at Low Temperatures

NASA Technical Reports Server (NTRS)

Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

2007-01-01

Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

Method and apparatus for rapid biohydrogen phenotypic screening of microorganisms using a chemochromic sensor

DOEpatents

Seibert, Michael; Benson, David K.; Flynn, Timothy Michael

2001-01-01

The invention provides an assay system for identifying a hydrogen-gas-producing organism, including a sensor film having a first layer comprising a transition metal oxide or oxysalt and a second layer comprising hydrogen-dissociative catalyst metal, the first and second layers having an inner and an outer surface wherein the inner surface of the second layer is deposited on the outer surface of the first layer, and a substrate disposed proximally to the outer surface of the second layer, the organism being isolated on the substrate.

Organic and inorganic passivation of p-type SnO thin-film transistors with different active layer thicknesses

NASA Astrophysics Data System (ADS)

Qu, Yunxiu; Yang, Jia; Li, Yunpeng; Zhang, Jiawei; Wang, Qingpu; Song, Aimin; Xin, Qian

2018-07-01

Bottom gated thin-film transistors (TFTs) with various sputtered SnO active layer thicknesses ranging from 10 to 30 nm and different passivation layers have been investigated. The device with 20 nm SnO showed the highest on/off ratio of 1.7 × 104 and the smallest subthreshold swing of 8.43 V dec‑1, and the mobility (0.76 cm2 V‑1 s‑1) was only slightly lower than in TFTs with a thicker SnO layer. However, both the mobility and the on/off ratio of the 15 nm SnO TFT dropped significantly by one order of magnitude. This indicated a strong influence of the top surface on the carrier transport, and we thus applied an organic or an inorganic encapsulation material to passivate the top surface. In the 20 nm TFT, the on/off ratio was doubled after passivation. The performance of the 15 nm TFT was improved even more dramatically with the on/off ratio increased by one order of magnitude and the mobility increased also significantly. Our experiment shows that polymethyl methacrylate passivation is more effective to reduce the shallow trap states, and Al2O3 is more effective in reducing the deep traps in the SnO channel.

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).

Soil organic matter doubles the cation exchange capacity of tropical soil under no-till farming in Brazil.

PubMed

Ramos, Fabricio T; Dores, Eliana Fg de Carvalho; Weber, Oscarlina L Dos Santos; Beber, Daniel C; Campelo, José H; Maia, João C de Souza

2018-07-01

Agricultural conservation practices increase total organic carbon storage in soil (T OCS ), a factor that is correlated with the physical and chemical qualities of highly weathered soils. In this study, we investigated the effects of T OCS on the physicochemical attributes of a Latosol after 10 years of no-till management in Mato Grosso State, Brazil. T COS was highly correlated (r = 0.92) with cation exchange capacity (CEC, pH = 7) and soil density. In the top 0.2 m soil layer, CEC increased by 25% with every 1.8 kg m -2 of stored organic carbon. Eliminating soil organic matter reduced CEC from an already low value of 8.40 cmol c kg -1 to 4.82 cmol c kg -1 . Humus is therefore clearly important for the formation of a negative liquid charge in a predominantly electropositive but clayey soil. We confirmed that T OCS is an indicator related to the physiochemical characteristics of weathered soils. Furthermore, our results demonstrate that the increased carbon storage under non-tilling systems is essential for guaranteeing weathered soil fertility in tropical climates. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

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

Engineering the Pores of Biomass-Derived Carbon: Insights for Achieving Ultrahigh Stability at High Power in High-Energy Supercapacitors.

PubMed

Thangavel, Ranjith; Kaliyappan, Karthikeyan; Ramasamy, Hari Vignesh; Sun, Xueliang; Lee, Yun-Sung

2017-07-10

Electrochemical supercapacitors with high energy density are promising devices due to their simple construction and long-term cycling performance. The development of a supercapacitor based on electrical double-layer charge storage with high energy density that can preserve its cyclability at higher power presents an ongoing challenge. Herein, we provide insights to achieve a high energy density at high power with an ultrahigh stability in an electrical double-layer capacitor (EDLC) system by using carbon from a biomass precursor (cinnamon sticks) in a sodium ion-based organic electrolyte. Herein, we investigated the dependence of EDLC performance on structural, textural, and functional properties of porous carbon engineered by using various activation agents. The results demonstrate that the performance of EDLCs is not only dependent on their textural properties but also on their structural features and surface functionalities, as is evident from the electrochemical studies. The electrochemical results are highly promising and revealed that the porous carbon with poor textural properties has great potential to deliver high capacitance and outstanding stability over 300 000 cycles compared with porous carbon with good textural properties. A very low capacitance degradation of around 0.066 % per 1000 cycles, along with high energy density (≈71 Wh kg -1 ) and high power density, have been achieved. These results offer a new platform for the application of low-surface-area biomass-derived carbons in the design of highly stable high-energy supercapacitors. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

French vertical flow constructed wetlands: a need of a better understanding of the role of the deposit layer.

PubMed

Molle, Pascal

2014-01-01

French vertical flow constructed wetlands, treating directly raw wastewater, have become the main systems implemented for communities under 2,000 population equivalent in France. Like in sludge drying reed beds, an organic deposit layer is formed over time at the top surface of the filter. This deposit layer is a key factor in the performance of the system as it impacts hydraulic, gas transfers, filtration efficiency and water retention time. The paper discusses the role of this deposit layer on the hydraulic and biological behaviour of the system. It presents results from different studies to highlight the positive role of the layer but, as well, the difficulties in modelling this organic layer. As hydraulic, oxygen transfers, and biological activity are interlinked and impacted by the deposit layer, it seems essential to focus on its role (and its quantification) to find new developments of vertical flow constructed wetlands fed with raw wastewater.

Acute oral toxicity and biodistribution study of zinc-aluminium-levodopa nanocomposite

NASA Astrophysics Data System (ADS)

Kura, Aminu Umar; Saifullah, Bullo; Cheah, Pike-See; Hussein, Mohd Zobir; Azmi, Norazrina; Fakurazi, Sharida

2015-03-01

Layered double hydroxide (LDH) is an inorganic-organic nano-layered material that harbours drug between its two-layered sheets, forming a sandwich-like structure. It is attracting a great deal of attention as an alternative drug delivery (nanodelivery) system in the field of pharmacology due to their relative low toxic potential. The production of these nanodelivery systems, aimed at improving human health through decrease toxicity, targeted delivery of the active compound to areas of interest with sustained release ability. In this study, we administered zinc-aluminium-LDH-levodopa nanocomposite (ZAL) and zinc-aluminium nanocomposite (ZA) to Sprague Dawley rats to evaluate for acute oral toxicity following OECD guidelines. The oral administration of ZAL and ZA at a limit dose of 2,000 mg/kg produced neither mortality nor acute toxic signs throughout 14 days of the observation. The percentage of body weight gain of the animals showed no significant difference between control and treatment groups. Animal from the two treated groups gained weight continuously over the study period, which was shown to be significantly higher than the weight at the beginning of the study ( P < 0.05). Biochemical analysis of animal serum showed no significant difference between rats treated with ZAL, ZA and controls. There was no gross lesion or histopathological changes observed in vital organs of the rats. The results suggested that ZAL and ZA at 2,000 mg/kg body weight in rats do not induce acute toxicity in the animals. Elemental analysis of tissues of treated animals demonstrated the wider distribution of the nanocomposite including the brain. In summary, findings of acute toxicity tests in this study suggest that zinc-aluminium nanocomposite intercalated with and the un-intercalated were safe when administered orally in animal models for short periods of time. It also highlighted the potential distribution ability of Tween-80 coated nanocomposite after oral administration.

Dynamics of a microbial community associated with manure hot spots as revealed by phospholipid fatty acid analyses.

PubMed Central

Frostegård, A; Petersen, S O; Bååth, E; Nielsen, T H

1997-01-01

Microbial community dynamics associated with manure hot spots were studied by using a model system consisting of a gel-stabilized mixture of soil and manure, placed between layers of soil, during a 3-week incubation period. The microbial biomass, measured as the total amount of phospholipid fatty acids (PLFA), had doubled within a 2-mm distance from the soil-manure interface after 3 days. Principal-component analyses demonstrated that this increase was accompanied by reproducible changes in the composition of PLFA, indicating changes in the microbial community structure. The effect of the manure was strongest in the 2-mm-thick soil layer closest to the interface, in which the PLFA composition was statistically significantly different (P < 0.05) from that of the unaffected soil layers throughout the incubation period. An effect was also observed in the soil layer 2 to 4 mm from the interface. The changes in microbial biomass and community structure were mainly attributed to the diffusion of dissolved organic carbon from the manure. During the initial period of microbial growth, PLFA, which were already more abundant in the manure than in the soil, increased in the manure core and in the 2-mm soil layer closest to the interface. After day 3, the PLFA composition of these layers gradually became more similar to that of the soil. The dynamics of individual PLFA suggested that both taxonomic and physiological changes occurred during growth. Examples of the latter were decreases in the ratios of 16:1 omega 7t to 16:1 omega 7c and of cyclopropyl fatty acids to their respective precursors, indicating a more active bacterial community. An inverse relationship between bacterial PLFA and the eucaryotic 20:4 PLFA (arachidonic acid) suggested that grazing was important. PMID:9172342

OLED emission zone measurement with high accuracy

NASA Astrophysics Data System (ADS)

Danz, N.; MacCiarnain, R.; Michaelis, D.; Wehlus, T.; Rausch, A. F.; Wächter, C. A.; Reusch, T. C. G.

2013-09-01

Highly efficient state of the art organic light-emitting diodes (OLED) comprise thin emitting layers with thicknesses in the order of 10 nm. The spatial distribution of the photon generation rate, i.e. the profile of the emission zone, inside these layers is of interest for both device efficiency analysis and characterization of charge recombination processes. It can be accessed experimentally by reverse simulation of far-field emission pattern measurements. Such a far-field pattern is the sum of individual emission patterns associated with the corresponding positions inside the active layer. Based on rigorous electromagnetic theory the relation between far-field pattern and emission zone is modeled as a linear problem. This enables a mathematical analysis to be applied to the cases of single and double emitting layers in the OLED stack as well as to pattern measurements in air or inside the substrate. From the results, guidelines for optimum emitter - cathode separation and for selecting the best experimental approach are obtained. Limits for the maximum spatial resolution can be derived.

The influence of hard-baking temperature applied for SU8 sensor layer on the sensitivity of capacitive chemical sensor

NASA Astrophysics Data System (ADS)

Klanjšek Gunde, Marta; Hauptman, Nina; Maček, Marijan; Kunaver, Matjaž

2009-06-01

SU8, the near-UV photosensitive epoxy-based polymer was used as a sensor layer in the capacitive chemical sensor, ready for integration with a generic double-metal CMOS technology. It was observed that the response of the sensor slowly increases with the temperature applied in hard-baking process as long as it remains below 300°C. At this temperature the response of the sensor abruptly increases and becomes almost threefold. It was shown that fully crosslinked structure of the sensor layer becomes opened and disordered when the sensor is hard-baked at temperatures between 300°C and 320°C, that is, still well below the degradation temperature of the polymer. These changes in chemical structure were analyzed by Fourier-transform infrared spectroscopy. The temperature-dependent changes of the sensor layer structure enable one to prepare a combination of capacitive chemical sensors with good discrimination between some volatile organic compounds.

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.

Gold Nanoclusters@Ru(bpy)₃²⁺-Layered Double Hydroxide Ultrathin Film as a Cathodic Electrochemiluminescence Resonance Energy Transfer Probe.

PubMed

Yu, Yingchang; Lu, Chao; Zhang, Meining

2015-08-04

Herein, it is the first report that a cathodic electrochemiluminescence (ECL) resonance energy transfer (ERET) system is fabricated by layer-by-layer (LBL) electrostatic assembly of CoAl layered double hydroxide (LDH) nanosheets with a mixture of blue BSA-gold nanoclusters (AuNCs) and Ru(bpy)3(2+) (denoted as AuNCs@Ru) on an Au electrode. The possible ECL mechanism indicates that the appearance of CoAl-LDH nanosheets generates a long-range stacking order of the AuNCs@Ru on an Au electrode, facilitating the occurrence of the ERET between BSA-AuNC donors and Ru(bpy)3(2+) acceptors on the as-prepared AuNCs@Ru-LDH ultrathin films (UTFs). Furthermore, it is observed that the cathodic ECL intensity can be quenched efficiently in the presence of 6-mercaptopurine (6-MP) in a linear range of 2.5-100 nM with a detection limit of 1.0 nM. On the basis of these interesting phenomena, a facile cathodic ECL sensor has successfully distinguished 6-MP from other thiol-containing compounds (e.g., cysteine and glutathione) in human serum and urine samples. The proposed sensing scheme opens a way for employing the layered UTFs as a platform for the cathodic ECL of Ru(bpy)3(2+).

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.

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.

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.

Effects of GAC layer on the performance of gravity-driven membrane filtration (GDM) system for rainwater recycling.

PubMed

Ding, An; Wang, Jinlong; Lin, Dachao; Zeng, Rong; Yu, Shengping; Gan, Zhendong; Ren, Nanqi; Li, Guibai; Liang, Heng

2018-01-01

Gravity-driven membrane filtration (GDM) is promising for decentralized rainwater recycling, owing to low maintenance and energy consumption. However, the organic removal by GDM process is sometimes undesirable and the quality of the permeate cannot meet the standard of water reuse. To improve this, granular activate carbon (GAC) was added as a particle layer on the membrane surface of GDM system. Additionally, a system with sand addition and a system with no particle addition were trialed as comparisons, to study the combined effects of particle hindering and adsorption on the removal efficacy of organics and the development of permeate flux. Results showed that GDM with a GAC layer improved removal efficiency of organics by 25%, and that GAC enhanced removal of florescent compounds (e.g., aromatic proteins, tryptophan proteins and humics), compared with the other two systems. Additionally, the permeate flux in three systems stabilized after Day 25, and kept stable until the end of the operation. However, the presence of GAC layer decreased the level of stable flux (3.2 L/m 2 h) compared with the control system (4.5 L/m 2 h). The factors responsible for the lower flux and severe membrane fouling in GAC layer assisted system were the combined effects of particle and adsorption which led to a denser bio-fouling layer with higher amount of biomass and extracellular polymeric substances contents (proteins and polysaccharides). Resistance distribution analyses revealed that GAC layer mainly increased hydraulically reversible resistance (occupied 93%) of the total resistance, indicating that the flux could be recovered easily by simple physical cleaning. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Optochemical sensor based on screenprinted fluorescent sensorspots surrounded by organic photodiodes for multianalyte detection

NASA Astrophysics Data System (ADS)

Kraker, E.; Lamprecht, B.; Haase, A.; Jakopic, G.; Abel, T.; Konrad, C.; Köstler, S.; Tscherner, M.; Stadlober, B.; Mayr, T.

2010-08-01

A compact, integrated photoluminescence based oxygen sensor, utilizing an organic light emitting device (OLED) as the light source and an organic photodiode (OPD) as the detection unit, is described. The detection system of the sensor array consists of an array of circular screen-printed fluorescent sensor spots surrounded by organic photodiodes as integrated fluorescence detectors. The OPD originates from the well-known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (CuPc, p-type material) and perylene tetracarboxylic bisbenzimidazole (PTCBi, n-type material). An additional layer of tris-8-hydroxyquinolinatoaluminium (Alq3, n-type material) was inserted between the PTCBi layer and cathode. An ORMOCERR layer was used as encapsulation layer. For excitation an organic light emitting diode is used. The sensor spot and the detector are processed on the same flexible substrate. This approach not only simplifies the detection system by minimizing the numbers of required optical components - no optical filters have to be used for separating the excitation light and the luminescent emission-, but also has a large potential for low-cost sensor applications. The feasibility of the concept is demonstrated by an integrated oxygen sensor, indicating good performance. Sensor schemes for other chemical parameters are proposed.