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Sample records for high ordered nanoporous

  1. Phenylthiourea Modified Highly Ordered Nanoporous Silica for Heavy Metal Ion (Hg2+ Trapping

    Directory of Open Access Journals (Sweden)

    A. R. Badiei

    2012-03-01

    Full Text Available The phenylthiourea-substituted triethoxysilane as a silane agent was synthesized and grafted on highly ordered nanoporous silica (LUS- 1 with a textured morphology and hexagonal array. This material (Tu-LUS-1 contained 0.8 mmol/g of soft base phenylthiourea group and surface area 760 m2 g-1  and was able to adsorb 0.75 mmolHg/g of TU-LUS-1 in endothermic reaction.

  2. Characterization of nanopores ordering in anodic alumina

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Piraux, L.

    2008-01-01

    A simple characterization method of the ordering of the nanopores is described for nanoporous anodized aluminium oxides. The method starts with image analysis on scanning electron microscopy representations for the purpose to find repetitive shapes and their centres, i.e. nanopores. Then triangle...

  3. Influence of Anodic Conditions on Self-ordered Growth of Highly Aligned Titanium Oxide Nanopores

    Directory of Open Access Journals (Sweden)

    Hernández-Vélez M

    2007-01-01

    Full Text Available AbstractSelf-aligned nanoporous TiO2templates synthesized via dc current electrochemical anodization have been carefully analyzed. The influence of environmental temperature during the anodization, ranging from 2 °C to ambient, on the structure and morphology of the nanoporous oxide formation has been investigated, as well as that of the HF electrolyte chemical composition, its concentration and their mixtures with other acids employed for the anodization. Arrays of self-assembled titania nanopores with inner pores diameter ranging between 50 and 100 nm, wall thickness around 20–60 nm and 300 nm in length, are grown in amorphous phase, vertical to the Ti substrate, parallel aligned to each other and uniformly disordering distributed over all the sample surface. Additional remarks about the photoluminiscence properties of the titania nanoporous templates and the magnetic behavior of the Ni filled nanoporous semiconductor Ti oxide template are also included.

  4. Hemi-ordered nanoporous carbon electrode material for highly selective determination of nitrite in physiological and environmental systems

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    Zhou, Shenghai; Wu, Hongmin; Wu, Ying; Shi, Hongyan; Feng, Xun; Jiang, Shang; Chen, Jian; Song, Wenbo, E-mail: wbsong@jlu.edu.cn

    2014-08-01

    Hemi-ordered nanoporous carbon (HONC) was obtained from a mesoporous silica template through a nano-replication method using furfuryl alcohol as the carbon source. The structure and morphology of HONC were characterized and analyzed in detail by X-ray diffraction, N{sub 2}-sorption, Raman spectroscopy and transmission electron microscopy. HONC was then demonstrated as active electrode material for selective determination of nitrite in either physiological or environmental system. Well separated oxidation peaks of ascorbic acid, dopamine, uric acid and nitrite were observed in physiological system, and simultaneous discrimination of catechol, hydroquinone, resorcinol and nitrite in environmental system was also accomplished. Distinctly improved performances for selective determination of nitrite (such as significantly fast and sensitive current response with especially high selectivity) coexisted with ascorbic acid, dopamine and uric acid in the physiological system, as well as with catechol, hydroquinone and resorcinol in the environmental system were achieved at HONC electrode material. The excellent discriminating ability and high selectivity for NO{sub 2}{sup −} determination were ascribed to the good electronic conductivity, unique hemi-ordered porous structure, large surface area and large number of edge plane defect sites contained on the surface of nanopore walls of HONC. Results in this work demonstrated that HONC is one of the promising catalytic electrode materials for nitrite sensor fabrication. - Highlights: • Hemi-ordered nanoporous carbon as an active electrode material • Good discriminating ability towards NO{sub 2}{sup −} from physiological or environmental system • Highly selective determination of nitrite with fast and sensitive current response.

  5. Green synthesis of large-scale highly ordered core@shell nanoporous Au@Ag nanorod arrays as sensitive and reproducible 3D SERS substrates.

    Science.gov (United States)

    Chen, Bin; Meng, Guowen; Huang, Qing; Huang, Zhulin; Xu, Qiaoling; Zhu, Chuhong; Qian, Yiwu; Ding, Yi

    2014-09-24

    We present a simple green synthetic approach to large-scale and highly ordered arrays of vertical nanoporous Au nanorods, with an ultrathin Ag-layer in situ electrodeposited on each nanoporous Au nanorod (denoted as core@shell nanoporous Au@Ag nanorod). As both the nanopores within each nanorod and the gaps between the neighboring nanorods create three-dimensional (3D) "hot spots" homogeneously distributed throughout the whole substrate, the core@shell nanoporous Au@Ag nanorod arrays were proved to be sensitive and reproducible surface-enhanced Raman scattering (SERS) substrates. Not only universal probe molecules (rhodamine 6G, R6G) but also nonadsorbing molecules (polychlorinated biphenyls, PCBs) have been detected by using the substrates. After mono-6-thio-β-cyclodextrin (HS-β-CD) was modified to efficiently capture more PCBs molecules, the detection limit of PCBs was further reduced to 5.35 × 10(-7) M. As a trial of practical application, R6G and PCBs with different molar ratios in their mixed solutions were identified, and two congeners of PCBs in their mixture could also be distinguished, showing great potentials in real-time simultaneous detection of multiple pollutants.

  6. Synthesis of new antibacterial composite coating for titanium based on highly ordered nanoporous silica and silver nanoparticles.

    Science.gov (United States)

    Massa, Miguel A; Covarrubias, Cristian; Bittner, Mauricio; Fuentevilla, Ignacio Andrés; Capetillo, Pavel; Von Marttens, Alfredo; Carvajal, Juan Carlos

    2014-12-01

    Infection is the most common factor that leads to dental titanium implant failure. Antibacterial implant surfaces based on nano-scale modifications of the titanium appear as an attractive strategy for control of peri-implantitis. In the present work, the preparation and antibacterial properties of a novel composite coating for titanium based on nanoporous silica and silver nanoparticles are presented. Starch-capped silver nanoparticles (AgNPs) were synthesized and then incorporated into sol-gel based solution system. The AgNP-doped nanoporous silica coatings were prepared on titanium surface using a combined sol-gel and evaporation-induced self-assembly (EISA) method. The coating nanostructure was characterized by XRD, SEM-EDX, and HR-TEM. Antibacterial activity was evaluated against Aggregatibacter actinomycetemcomitans, a representative pathogen of dental peri-implantitis. Colony-forming units (CFUs) were counted within the biofilm and at the planktonic state. Biofilm development was quantified using crystal violet staining and viability of adherent bacteria was confirmed with the Live/Dead fluorescence assay. Silica-based composite coating containing AgNPs (AgNP/NSC) was prepared on titanium surface by direct incorporation of AgNP suspension into the sol-gel system. The self-assembly technique enabled the spontaneous formation of a highly ordered nanoporosity in the coating structure, which is a desired property for osseointegration aspects of titanium implant surface. AgNP/NSC coating produces a strong antibacterial effect on titanium surface by not only killing the adherent bacteria but also reducing the extent of biofilm formation. Biofilm survival is reduced by more than 70% on the AgNP/NSC-modified titanium surface, compared to the control. This antibacterial effect was verified for up to 7 days of incubation. The long-term antibacterial activity exhibited by the nanostructured AgNP/NSC-titanium surface against A. actinomycetemcomitans suggests that this

  7. Catalytic properties of highly ordered crystalline nanoporous tungsten oxide in butanol dehydration.

    Science.gov (United States)

    Choi, Hyeonhee; Lee, Eunok; Jin, Mingshi; Park, Young-Kwon; Kim, Ji Man; Jeon, Jong-Ki

    2014-11-01

    Highly ordered mesoporous tungsten oxide (meso-WO3) was successfully synthesized using mesoporous silica KIT-6 as a hard template via the nanoreplication method. The physicochemical properties of meso-WO3 were characterized by X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption of ammonia, and infra-red spectroscopy of adsorbed pyridine. No oxidation state other than WO3 was observed in the meso-WO3 sample. Lewis acid sites were dominant in meso-WO3, which could be confirmed by infra-red spectroscopy of pyridine and temperature-programmed desorption of ammonia. Its catalytic behavior in 2-butanol dehydration was investigated in a fixed bed reactor and compared with that of the WO3/MCM-41 catalyst prepared by the atomic layer deposition method. The meso-WO3 catalyst exhibited higher 2-butanol dehydration activity than that of the WO3/MCM-41 catalyst, which is ascribed to the stronger acidity as well as higher amount of acid sites that are mainly composed of Lewis acid sites in the meso-WO3 catalyst.

  8. High Density Methane Storage in Nanoporous Carbon

    Science.gov (United States)

    Rash, Tyler; Dohnke, Elmar; Soo, Yuchoong; Maland, Brett; Doynov, Plamen; Lin, Yuyi; Pfeifer, Peter; Mriglobal Collaboration; All-Craft Team

    2014-03-01

    Development of low-pressure, high-capacity adsorbent based storage technology for natural gas (NG) as fuel for advanced transportation (flat-panel tank for NG vehicles) is necessary in order to address the temperature, pressure, weight, and volume constraints present in conventional storage methods (CNG & LNG.) Subcritical nitrogen adsorption experiments show that our nanoporous carbon hosts extended narrow channels which generate a high surface area and strong Van der Waals forces capable of increasing the density of NG into a high-density fluid. This improvement in storage density over compressed natural gas without an adsorbent occurs at ambient temperature and pressures ranging from 0-260 bar (3600 psi.) The temperature, pressure, and storage capacity of a 40 L flat-panel adsorbed NG tank filled with 20 kg of nanoporous carbon will be featured.

  9. Plasmonic devices and sensors built from ordered nanoporous materials.

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Benjamin W.; Kobayashi, Yoji (University of California, Berkeley); Houk, Ronald J. T.; Allendorf, Mark D.; Long, Jeffrey R. (University of California, Berkeley); Robertson, Ian M. (University of Illinois Urbana-Champaign, Urbana, IL); House, Stephen D. (University of Illinois Urbana-Champaign, Urbana, IL); Graham, Dennis D. (University of Illinois Urbana-Champaign, Urbana, IL); Talin, Albert Alec (National Institute of Standards & Technology, Gaithersburg, MD); Chang, Noel N. (University of Illinois Urbana-Champaign, Urbana, IL); El Gabaly Marquez, Farid

    2009-09-01

    The objective of this project is to lay the foundation for using ordered nanoporous materials known as metal-organic frameworks (MOFs) to create devices and sensors whose properties are determined by the dimensions of the MOF lattice. Our hypothesis is that because of the very short (tens of angstroms) distances between pores within the unit cell of these materials, enhanced electro-optical properties will be obtained when the nanopores are infiltrated to create nanoclusters of metals and other materials. Synthetic methods used to produce metal nanoparticles in disordered templates or in solution typically lead to a distribution of particle sizes. In addition, creation of the smallest clusters, with sizes of a few to tens of atoms, remains very challenging. Nanoporous metal-organic frameworks (MOFs) are a promising solution to these problems, since their long-range crystalline order creates completely uniform pore sizes with potential for both steric and chemical stabilization. We report results of synthetic efforts. First, we describe a systematic investigation of silver nanocluster formation within MOFs using three representative MOF templates. The as-synthesized clusters are spectroscopically consistent with dimensions {le} 1 nm, with a significant fraction existing as Ag{sub 3} clusters, as shown by electron paramagnetic resonance. Importantly, we show conclusively that very rapid TEM-induced MOF degradation leads to agglomeration and stable, easily imaged particles, explaining prior reports of particles larger than MOF pores. These results solve an important riddle concerning MOF-based templates and suggest that heterostructures composed of highly uniform arrays of nanoparticles within MOFs are feasible. Second, a preliminary study of methods to incorporate fulleride (K{sub 3}C{sub 60}) guest molecules within MOF pores that will impart electrical conductivity is described.

  10. Highly cross-linked nanoporous polymers

    Science.gov (United States)

    Steckle, Jr., Warren P.; Apen, Paul G.; Mitchell, Michael A.

    1997-01-01

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

  11. Nanoporous silica membranes with high hydrothermal stability

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Magnacca, Giualiana; Yue, Yuanzheng

    Despite the use of sol-gel derived nanoporous silica membranes in substitution of traditional separation processes is expected leading to vast energy savings, their intrinsic poor steam-stability hampers their application at an industrial level. Transition metal ions can be used as dopant...... to improve the stability of nanoporous silica structure. This work is a quantitative study on the impact of type and concentration of transition metal ions on the microporous structure and stability of amorphous silica-based membranes, which provides information on how to design chemical compositions...... and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile nanoporous structure...

  12. Nanoporous Carbon Nitride: A High Efficient Filter for Seawater Desalination

    CERN Document Server

    Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2015-01-01

    The low efficiency of commercially-used reverse osmosis (RO) membranes has been the main obstacle in seawater desalination application. Here, we report the auspicious performance, through molecular dynamics simulations, of a seawater desalination filter based on the recently-synthesized graphene-like carbon nitride (g-C2N) [Nat. Commun., 2015, 6, 6486]. Taking advantage of the inherent nanopores and excellent mechanical properties of g-C2N filter, highly efficient seawater desalination can be achieved by modulating the nanopores under tensile strain. The water permeability can be improved by two orders of magnitude compared to RO membranes, which offers a promising approach to the global water shortage solution.

  13. MODELING THE SELF-ASSEMBLY OF ORDERED NANOPOROUS MATERIALS

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    Monson, Peter [University of Massachusetts; Auerbach, Scott [University of Massachusetts

    2017-11-13

    This report describes progress on a collaborative project on the multiscale modeling of the assembly processes in the synthesis of nanoporous materials. Such materials are of enormous importance in modern technology with application in the chemical process industries, biomedicine and biotechnology as well as microelectronics. The project focuses on two important classes of materials: i) microporous crystalline materials, such as zeolites, and ii) ordered mesoporous materials. In the first case the pores are part of the crystalline structure, while in the second the structures are amorphous on the atomistic length scale but where surfactant templating gives rise to order on the length scale of 2 - 20 nm. We have developed a modeling framework that encompasses both these kinds of materials. Our models focus on the assembly of corner sharing silica tetrahedra in the presence of structure directing agents. We emphasize a balance between sufficient realism in the models and computational tractibility given the complex many-body phenomena. We use both on-lattice and off-lattice models and the primary computational tools are Monte Carlo simulations with sampling techniques and ensembles appropriate to specific situations. Our modeling approach is the first to capture silica polymerization, nanopore crystallization, and mesopore formation through computer-simulated self assembly.

  14. Nanoporous PtFe alloys as highly active and durable electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Duan, Huimei; Hao, Qin; Xu, Caixia

    2014-12-01

    Nanoporous PtFe alloys with two different bimetallic ratios are fabricated by selectively dealloying PtFeAl ternary alloys, characterized by nanoscaled bicontinuous network skeleton with interconnected hollow channels extending in all three dimensions. The reactive components in PtFeAl ternary alloy were sequentially leached out in a highly controllable manner, generating nanoporous architecture with different bimetallic ratios and the typical ligament size as small as 5 nm. These nanoporous PtFe alloys exhibit much enhanced electrocatalytic activity for oxygen reduction reaction compared with the PtFe/C and Pt/C catalysts. The specific and mass activities for oxygen reduction follow the order of nanoporous Pt75Fe25 > nanoporous Pt55Fe45 > PtFe/C > Pt/C. In the absence of any catalyst support, the structure stability of nanoporous PtFe alloys is greatly enhanced with less loss of the electrochemical surface area and the oxygen reduction activity upon long-term potential scan tests compared with PtFe/C and Pt/C catalysts. The as-made nanoporous PtFe alloys thus hold great application potential as promising cathode electrocatalyst in proton exchange membrane fuel cells with the advantages of easy preparation along with superior oxygen reduction activity and durability.

  15. Determination of picomolar silver concentrations by differential pulse anodic stripping voltammetry at a carbon paste electrode modified with phenylthiourea-functionalized high ordered nanoporous silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Javanbakht, Mehran [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Nano Science and Technology Research Center, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: mehranjavanbakht@gmail.com; Divsar, Faten [Department of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Badiei, Alireza [School of Chemistry, University College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Fatollahi, Fatemeh [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Khaniani, Yeganeh [School of Chemistry, University College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza; Norouzi, Parviz [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Chaloosi, Marzieh [Department of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Ziarani, Ghodsi Mohammadi [Department of Chemistry, University of Alzahra, Tehran (Iran, Islamic Republic of)

    2009-09-30

    This study introduces the design of an anodic stripping voltammetric (ASV) method for the silver ion determination at a carbon paste electrode (CPE), chemically modified with phenylthiourea-nanoporous silica gel (Tu-SBA-15-CPE). The electroanalytical pro includes two steps: preconcentration of metal ions at an electrode surface, followed by quantification of the accumulated species by differential pulse anodic stripping voltammetric methods. Factors affecting the performance of the anodic stripping were investigated, including the modifier quantity in the paste, the electrolyte concentrations, the solution pH and the accumulation potential or time. The most sensitive and reliable electrode contained 10% Tu-SBA-15 and 90% carbon paste. The accumulation potential and time were set at, -200 mV and 300 s, respectively, and the scan rate at 50 mV s{sup -1} in the scan range of -200 to 700 mV. The resulting electrode demonstrated a linear response over range of silver ion concentration of 8.0-80 pmol/L with detection limit (S/N = 3) of 5 pmol/L. The prepared electrodes were used for the silver determination in sea and tap water samples and very good recovery results were obtained. The accuracy was assessed through recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

  16. Biomimetic solution against dewetting in a highly hydrophobic nanopore.

    Science.gov (United States)

    Picaud, Fabien; Paris, Guillaume; Gharbi, Tijani; Balme, Sébastien; Lepoitevin, Mathilde; Tangaraj, Vidhyadevi; Bechelany, Mikhael; Janot, Jean Marc; Balanzat, Emmanuel; Henn, François

    2016-06-14

    A water molecule is the foundation of life and is the primary compound in every living system. While many of its properties are understood in a bulk solvent, its behavior in a small hydrophobic nanopore still raises fundamental questions. For instance, a wetting/dewetting transition in a hydrophobic solid-state or a polymer nanopore occurs stochastically and can only be prevented by external physical stimuli. Controlling these transitions would be a primary requirement to improve many applications. Some biological channels, such as gramicidin A (gA) proteins, show a high rate of water and ion diffusion in their central subnanochannel while their external surface is highly hydrophobic. The diameter of this channel is significantly smaller than the inner size of the lowest artificial nanopore in which water drying occurs (i.e. 1.4 nm). In this paper, we propose an innovative idea to generate nanopore wetting as a result of which the application of an external field is no longer required. In a nanopore, the drying or wetting of the inner walls occurs randomly (in experiments and in simulations). However, we have shown how the confinement of gA, in a dried hydrophobic nanopore, rapidly generates a stable wetting of the latter. We believe that this simple idea, based on biomimetism, could represent a real breakthrough that could help to improve and develop new nanoscale applications.

  17. High-density nanopore array for selective biomolecule transport.

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Kamlesh D.

    2011-11-01

    Development of sophisticated tools capable of manipulating molecules at their own length scale enables new methods for chemical synthesis and detection. Although nanoscale devices have been developed to perform individual tasks, little work has been done on developing a truly scalable platform: a system that combines multiple components for sequential processing, as well as simultaneously processing and identifying the millions of potential species that may be present in a biological sample. The development of a scalable micro-nanofluidic device is limited in part by the ability to combine different materials (polymers, metals, semiconductors) onto a single chip, and the challenges with locally controlling the chemical, electrical, and mechanical properties within a micro or nanochannel. We have developed a unique construct known as a molecular gate: a multilayered polymer based device that combines microscale fluid channels with nanofluidic interconnects. Molecular gates have been demonstrated to selectively transport molecules between channels based on size or charge. In order to fully utilize these structures, we need to develop methods to actively control transport and identify species inside a nanopore. While previous work has been limited to creating electrical connections off-channel or metallizing the entire nanopore wall, we now have the ability to create multiple, separate conductive connections at the interior surface of a nanopore. These interior electrodes will be used for direct sensing of biological molecules, probing the electrical potential and charge distribution at the surface, and to actively turn on and off electrically driven transport of molecules through nanopores.

  18. Highly sensitive detection using microring resonator and nanopores

    Science.gov (United States)

    Bougot-Robin, K.; Hoste, J. W.; Le Thomas, N.; Bienstman, P.; Edel, J. B.

    2016-04-01

    One of the most significant challenges facing physical and biological scientists is the accurate detection and identification of single molecules in free-solution environments. The ability to perform such sensitive and selective measurements opens new avenues for a large number of applications in biological, medical and chemical analysis, where small sample volumes and low analyte concentrations are the norm. Access to information at the single or few molecules scale is rendered possible by a fine combination of recent advances in technologies. We propose a novel detection method that combines highly sensitive label-free resonant sensing obtained with high-Q microcavities and position control in nanoscale pores (nanopores). In addition to be label-free and highly sensitive, our technique is immobilization free and does not rely on surface biochemistry to bind probes on a chip. This is a significant advantage, both in term of biology uncertainties and fewer biological preparation steps. Through combination of high-Q photonic structures with translocation through nanopore at the end of a pipette, or through a solid-state membrane, we believe significant advances can be achieved in the field of biosensing. Silicon microrings are highly advantageous in term of sensitivity, multiplexing, and microfabrication and are chosen for this study. In term of nanopores, we both consider nanopore at the end of a nanopipette, with the pore being approach from the pipette with nanoprecise mechanical control. Alternatively, solid state nanopores can be fabricated through a membrane, supporting the ring. Both configuration are discussed in this paper, in term of implementation and sensitivity.

  19. Sorption and diffusion of phenols onto well-defined ordered nanoporous monolithic silicas.

    Science.gov (United States)

    El-Safty, S A

    2003-04-01

    The sorption of phenol, and o-, m-, and p-aminophenol (o-, m-, and p-AP) onto highly ordered mesoporous silicas (HOM) with cubic Im3m (HOM-1), hexagonal H(I) (HOM-2), 3-D hexagonal p6(3)/mmc (HOM-3), cubic Ia3d (HOM-5), lamellar L( infinity ) (HOM-6), and solid phase S (HOM-8) materials has been investigated kinetically. Nanostructured silica molecular sieves have been prepared at 25 and 60 degrees C with lyotropic liquid-crystalline phases of the nonionic surfactant (Brij 76) that was used as a structure-directing agent. Such nanostructured silicas have been studied by 29Si nuclear magnetic resonance (29Si NMR), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method for nitrogen adsorption and surface area measurements, and transmission electron microscopy (TEM) techniques after synthesis and sorption. It was found that all materials exhibit well-defined long-range porous architectures without significant loss of the ordered texture during phenol sorption. The kinetics of phenol sorption has been studied spectrophotometrically at different temperatures (25-40 degrees C; +/-0.1 range). The sorption rate is zero order in all phenols sorbed, and increases directly in the pattern P >m-AP > o-AP > p-AP, which reflects the mobility of the phenol compounds on the particle pores. The isothermal sorption and the kinetic parameters were discussed and it was established that a diffusion-controlled process characterizes phenol sorption. Furthermore, the mechanism of phenol sorption was deduced to be predominantly particle diffusion. The diffusion coefficients were determined using Fick's equation. The trend of diffusion of all phenols onto nanoporous silica was HOM-8 > HOM-2 > HOM-6 > HOM-5 > HOM-1 > HOM-3, reflecting the effect of the uniform pore size distribution and the internal surface area of the nanostructured silicas on the diffusion process.

  20. Highly efficient removal of basic blue 41 with nanoporous silica

    Directory of Open Access Journals (Sweden)

    Mansoureh Zarezadeh-Mehrizi

    2014-03-01

    Full Text Available The adsorption characteristics of basic blue 41 from aqueous solution were investigated using nanoporous silica (NPS. NPS with an average pore diameter of 2.4 nm and a surface area of 1030 m2/g was synthesized by using nonyl phenol ethoxylated decylether (NP-10 as structure directing agent (SDA and ethyl silicate 40% (ETS-40 under acidic condition. This adsorbent was analyzed by means of small-angle X-ray scattering, scanning electron microscopy, N2 adsorption–desorption isotherm and Fourier transforms infrared spectroscopy. The kinetic data reveals that the adsorption process follows the linear form of the pseudo-second-order model. The adsorption isotherm was fitted well to the Langmuir data. The monolayer adsorption capacity of adsorbent was found to be 345 mg/g.

  1. Atomic layer deposition of nanoporous biomaterials.

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, R. J.; Adiga, S. P.; Pellin, M. J.; Curtiss, L. A.; Stafslien, S.; Chisholm, B.; Monteiro-Riviere, N. A.; Brigmon, R. L.; Elam, J. W.; Univ. of North Carolina; North Carolina State Univ.; Eastman Kodak Co.; North Dakota State Univ.; SRL

    2010-03-01

    Due to its chemical stability, uniform pore size, and high pore density, nanoporous alumina is being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. In recent work, we have examined the use of atomic layer deposition for coating the surfaces of nanoporous alumina membranes. Zinc oxide coatings were deposited on nanoporous alumina membranes using atomic layer deposition. The zinc oxide-coated nanoporous alumina membranes demonstrated antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that atomic layer deposition is an attractive technique for modifying the surfaces of nanoporous alumina membranes and other nanostructured biomaterials. Nanoporous alumina, also known as anodic aluminum oxide (AAO), is a nanomaterial that exhibits several unusual properties, including high pore densities, straight pores, small pore sizes, and uniform pore sizes. In 1953, Keller et al. showed that anodizing aluminum in acid electrolytes results in a thick layer of nearly cylindrical pores, which are arranged in a close-packed hexagonal cell structure. More recently, Matsuda & Fukuda demonstrated preparation of highly ordered platinum and gold nanohole arrays using a replication process. In this study, a negative structure of nanoporous alumina was initially fabricated and a positive structure of a nanoporous metal was subsequently fabricated. Over the past fifteen years, nanoporous alumina membranes have been used as templates for growth of a variety of nanostructured materials, including nanotubes, nanowires, nanorods, and nanoporous membranes.

  2. High-bandwidth nanopore data analysis by using a modified hidden Markov model.

    Science.gov (United States)

    Zhang, Jianhua; Liu, Xiuling; Ying, Yi-Lun; Gu, Zhen; Meng, Fu-Na; Long, Yi-Tao

    2017-03-09

    Nanopore-based sensing is an emerging analytical technique with a number of important applications, including single-molecule detection and DNA sequencing. In this paper, we developed a Modified Hidden Markov Model (MHMM) to analyze directly the raw (unfiltered) nanopore current blockade data, which significantly reduced the filtering-induced distortion of the nanopore events. Traditionally, prior to further analysis, the measured nanopore data need to be pre-filtered to supress the strong noises. Nonetheless, this would result in the distortion of the shape of the blockade current especially for rapid translocations and bumping blockades. The HMM has been proved to be robust with respect to highly noisy data and thus ideally suitable for processing raw nanopore data directly. Unfortunately, its performance is somehow sensitive to the initial parameters usually preset arbitrarily. To overcome this problem, we use the Fuzzy c-Means (FCM) algorithm to initialize the HMM parameters automatically. Then we use the Viterbi training algorithm to optimize the HMM. Finally, the application results on both the simulated and experimental data are presented to demonstrate the practicability of the developed method for accurate detection of the nanopore current blockade events. The proposed method enables detection of the nanopore events at the highest bandwidth of the commercial instruments to extract the true useful information about the single molecules under analysis.

  3. Fabrication of highly oriented nanoporous fibers via airflow bubble-spinning

    Science.gov (United States)

    Liu, Fujuan; Li, Shaokai; Fang, Yue; Zheng, Fangfang; Li, Junhua; He, Jihuan

    2017-11-01

    Highly oriented Poly(lactic acid) (PLA) nanofibers with nanoporous structures has been successfully fabricated via airflow bubble-spinning without electrostatic hazard. In this work, the volatile solvent was necessary for preparing the nanoporous fiber, which was attributed to the competition between phase separation and solvent evaporation. The interconnected porous structures were affected by the processing variables of solution concentration, airflow temperature, collecting distance and relative humidity (RH). Besides, the rheological properties of solutions were studied and the highly oriented PLA nanofibers with nanoporous structure were also completely characterized using scanning electron microscope (SEM). This study provided a novel technique that successfully gets rid of the potential safety hazards caused by unexpected static to prepare highly oriented nanoporous fibers, which would demonstrate an impressive prospect for the fields of adsorption and filtration.

  4. Ordered nanoporous silica as carriers for improved delivery of water insoluble drugs: a comparative study between three dimensional and two dimensional macroporous silica.

    Science.gov (United States)

    Wang, Ying; Zhao, Qinfu; Hu, Yanchen; Sun, Lizhang; Bai, Ling; Jiang, Tongying; Wang, Siling

    2013-01-01

    The goal of the present study was to compare the drug release properties and stability of the nanoporous silica with different pore architectures as a matrix for improved delivery of poorly soluble drugs. For this purpose, three dimensional ordered macroporous (3DOM) silica with 3D continuous and interconnected macropores of different sizes (200 nm and 500 nm) and classic mesoporous silica (ie, Mobil Composition of Matter [MCM]-41 and Santa Barbara Amorphous [SBA]-15) with well-ordered two dimensional (2D) cylindrical mesopores were successfully fabricated and then loaded with the model drug indomethacin (IMC) via the solvent deposition method. Scanning electron microscopy (SEM), N2 adsorption, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were applied to systematically characterize all IMC-loaded nanoporous silica formulations, evidencing the successful inclusion of IMC into nanopores, the reduced crystallinity, and finally accelerated dissolution of IMC. It was worth mentioning that, in comparison to 2D mesoporous silica, 3DOM silica displayed a more rapid release profile, which may be ascribed to the 3D interconnected pore networks and the highly accessible surface areas. The results obtained from the stability test indicated that the amorphous state of IMC entrapped in the 2D mesoporous silica (SBA-15 and MCM-41) has a better physical stability than in that of 3DOM silica. Moreover, the dissolution rate and stability of IMC loaded in 3DOM silica was closely related to the pore size of macroporous silica. The colorimetric 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Cell Counting Kit (CCK)-8 assays in combination with direct morphology observations demonstrated the good biocompatibility of nanoporous silica, especially for 3DOM silica and SBA-15. The present work encourages further study of the drug release properties and stability of drug entrapped in different pore architecture of silica in order to realize

  5. Nanoporous Activated Carbon Derived from Rice Husk for High Performance Supercapacitor

    Directory of Open Access Journals (Sweden)

    Huaxing Xu

    2014-01-01

    Full Text Available Nanoporous activated carbon material was produced from the waste rice husks (RHs by precarbonizing RHs and activating with KOH. The morphology, structure, and specific surface area were investigated. The nanoporous carbon has the average pore size of 2.2 nm and high specific area of 2523.4 m2 g−1. The specific capacitance of the nanoporous carbon is calculated to be 250 F g−1 at the current density of 1 A g−1 and remains 80% for 198 F g−1 at the current density of 20 A g−1. The nanoporous carbon electrode exhibits long-term cycle life and could keep stable capacitance till 10,000 cycles. The consistently high specific capacitance, rate capacity, and long-term cycle life ability makes it a potential candidate as electrode material for supercapacitor.

  6. Ultrathin high-resolution flexographic printing using nanoporous stamps.

    Science.gov (United States)

    Kim, Sanha; Sojoudi, Hossein; Zhao, Hangbo; Mariappan, Dhanushkodi; McKinley, Gareth H; Gleason, Karen K; Hart, A John

    2016-12-01

    Since its invention in ancient times, relief printing, commonly called flexography, has been used to mass-produce artifacts ranging from decorative graphics to printed media. Now, higher-resolution flexography is essential to manufacturing low-cost, large-area printed electronics. However, because of contact-mediated liquid instabilities and spreading, the resolution of flexographic printing using elastomeric stamps is limited to tens of micrometers. We introduce engineered nanoporous microstructures, comprising polymer-coated aligned carbon nanotubes (CNTs), as a next-generation stamp material. We design and engineer the highly porous microstructures to be wetted by colloidal inks and to transfer a thin layer to a target substrate upon brief contact. We demonstrate printing of diverse micrometer-scale patterns of a variety of functional nanoparticle inks, including Ag, ZnO, WO3, and CdSe/ZnS, onto both rigid and compliant substrates. The printed patterns have highly uniform nanoscale thickness (5 to 50 nm) and match the stamp features with high fidelity (edge roughness, ~0.2 μm). We derive conditions for uniform printing based on nanoscale contact mechanics, characterize printed Ag lines and transparent conductors, and achieve continuous printing at a speed of 0.2 m/s. The latter represents a combination of resolution and throughput that far surpasses industrial printing technologies.

  7. Optimizing Nanopore Surface Properties for High-Efficiency Water Desalination

    Science.gov (United States)

    Cohen-Tanugi, David; Grossman, Jeffrey

    2011-03-01

    As water resources worldwide become rapidly scarcer, it is becoming increasingly important to devise new techniques to obtain clean water from seawater. At present, water purification technologies are limited by costly energy requirements relative to the theoretical thermodynamic limit and by insufficient understanding of the physical processes underlying ion filtration and fluid transport at the molecular scale. New advances in computational materials science offer a promising way to deepen our understanding of these physical phenomena. In this presentation, we describe a new approach for high-efficiency water desalination based on surface-engineered porous materials. This approach is especially relevant for promising technologies such as nanofiltration and membrane distillation, which offers promising advantages over traditional desalination technologies using mesoporous membranes that are only permeable to pure water vapor. More accurate molecular modeling of mesoporous and nanoporous materials represents a key step towards efficient large-scale treatment of seawater. Results regarding the effect of pore properties (surface texture, morphology, density, tortuosity) on desired performance characteristics such as ion selectivity, maximal water flux and energy requirements will be presented.

  8. Toward high permeability, selectivity and controllability of water desalination with FePc nanopores.

    Science.gov (United States)

    Deng, Qingming; Pan, Jun; Yin, Xiaohui; Wang, Xiaofeng; Zhao, Lina; Kang, Seung-gu; Jimenez-Cruz, Camilo A; Zhou, Ruhong; Li, Jingyuan

    2016-03-21

    Nanoporous materials exhibit promising potential in water transportation applications, especially in ocean water desalination. It is highly desired to have great permeability, selectivity and controllability in the desalination performance of these nanopores. However, it is still a challenge to achieve all three features in one material or device. Here, we demonstrate efficient and controllable water desalination with a nanoporous 2D Fe phthalocyanine (FePc) membrane using molecular dynamics simulations. We find the FePc membrane not only conducts fast water flow, but it also suppresses ion permeation. The selectivity is attributed to a mechanism distinct from the traditional steric exclusion: cations are excluded due to electrostatic repulsion, whereas anions can be trapped in the nanopore and induce the reorganization of ions in the vicinity of the nanopore, which in turn creates a tendency for the trapped anions to move back into the saline reservoir. More interestingly, we find such mechanism is largely due to the sufficiently strong electrostatic interaction of the charged nanopore region with ions and is not restricted to the FePc nanopore. In addition, the number of protonated nitrogen atoms in FePc pores can be modulated by adjusting the pH value of the solution. The extent of the anion occupancy can thus be regulated, giving rise to control of the water flow. Taken together, great permeability, selectivity and controllability can be achieved with this nanosheet system. Moreover, our study suggests there is an alternative mechanism of water desalination which may be realized by intrinsically nanoporous materials such as FePc membranes.

  9. Highly magnetic nanoporous carbon/iron-oxide hybrid materials.

    Science.gov (United States)

    Alam, Sher; Anand, Chokkalingam; Lakhi, Kripal Singh; Choy, Jin-Ho; Cha, Wang Soo; Elzhatry, Ahmed; Al-Deyab, Salem S; Ohya, Yutaka; Vinu, Ajayan

    2014-11-10

    The preparation of size-controllable Fe2O3 nanoparticles grown in nanoporous carbon with tuneable pore diameters is reported. These hybrid materials exhibit strong non-linear magnetic properties and a magnetic moment of approximately 229 emu g(-1), which is the highest value ever reported for nanoporous hybrids, and can be attributed to the nanosieve effect and the strong interaction between the nanoparticles and the carbon walls. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. High Performance Palladium Supported on Nanoporous Carbon under Anhydrous Condition

    Science.gov (United States)

    Yang, Zehui; Ling, Ying; Zhang, Yunfeng; Xu, Guodong

    2016-11-01

    Due to the high cost of polymer electrolyte fuel cells (PEFCs), replacing platinum (Pt) with some inexpensive metal was carried out. Here, we deposited palladium nanoparticles (Pd-NPs) on nanoporous carbon (NC) after wrapping by poly[2,2‧-(2,6-pyridine)-5,5‧-bibenzimidazole] (PyPBI) doped with phosphoric acid (PA) and the Pd-NPs size was successfully controlled by varying the weight ratio between Pd precursor and carbon support doped with PA. The membrane electrode assembly (MEA) fabricated from the optimized electrocatalyst with 0.05 mgPd cm-2 for both anode and cathode sides showed a power density of 76 mW cm-2 under 120 °C without any humidification, which was comparable to the commercial CB/Pt, 89 mW cm-2 with 0.45 mgPt cm-2 loaded in both anode and cathode. Meanwhile, the power density of hybrid MEA with 0.45 mgPt cm-2 in cathode and 0.05 mgPd cm-2 in anode reached 188 mW cm-2. The high performance of the Pt-free electrocatalyst was attributed to the porous structure enhancing the gas diffusion and the PyPBI-PA facilitating the proton conductivity in catalyst layer. Meanwhile, the durability of Pd electrocatalyst was enhanced by coating with acidic polymer. The newly fabricated Pt-free electrocatalyst is extremely promising for reducing the cost in the high-temperature PEFCs.

  11. Study of preparation and surface morphology of self-ordered nanoporous alumina; Estudo da preparacao e da morfologia de superficie de alumina nanoporosa auto-organizada

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Elisa Marchezini; Martins, Maximiliano Delany, E-mail: elisamarch@gmail.com, E-mail: MG.mdm@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG. (Brazil); Silva, Ronald Arreguy, E-mail: arregsilva@yahoo.com.br [Centro Universitario de Belo Horizonte (UniBH), Belo Horizonte, MG (Brazil)

    2013-07-01

    Nanoporous alumina is a typical material that exhibits self-ordered nanochannels spontaneously organized in hexagonal shape. Produced by anodizing of metallic aluminum, it has been used as a template for production of materials at the nanoscale. This work aimed to study the preparation of nanoporous alumina by anodic anodizing of metallic aluminum substrates. The nanoporous alumina was prepared following the methodology proposed by Masuda and Fukuda (1995), a two-step method consisting of anodizing the aluminum sample in the potentiostatic mode, removing the layer of aluminum oxide (alumina) formed and then repeat the anodization process under the same conditions as the first anodization. This method produces nanoporous alumina with narrow pore diameter distribution and well-ordered structure. (author)

  12. Metallic Muscles at Work : High Rate Actuation in Nanoporous Gold/Polyaniline Composites

    NARCIS (Netherlands)

    Detsi, Eric; Onck, Patrick; De Hosson, Jeff Th. M.

    Metallic muscles made of nanoporous metals suffer from serious drawbacks caused by the usage of an aqueous electrolyte for actuation. An aqueous electrolyte prohibits metallic muscles from operating in dry environments and hampers a high actuation rate due to the low ionic conductivity of

  13. High-volumetric performance aligned nano-porous microwave exfoliated graphite oxide-based electrochemical capacitors.

    Science.gov (United States)

    Ghaffari, Mehdi; Zhou, Yue; Xu, Haiping; Lin, Minren; Kim, Tae Young; Ruoff, Rodney S; Zhang, Q M

    2013-09-20

    Ultra-high volumetric performance electrochemical double layer capacitors based on high density aligned nano-porous microwave exfoliated graphite oxide have been studied. Elimination of macro-, meso-, and larger micro-pores from electrodes and controlling the nano-morphology results in very high volumetric capacitance, energy, and power density values. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Plasma-induced nanoporous metal oxides with nitrogen doping for high-performance electrocatalysis

    Science.gov (United States)

    Wang, Min

    2017-06-01

    The oxygen evolution reaction (OER) is a critical reaction in energy storage and conversion systems such as metal-air batteries and water splitting. The current commercial OER catalysts are the noble metal based materials, which have a high cost and a limited supply. Xu et al have prepared the nanoporous N-Co3O4 materials as cost-effective and high efficient electrocatalysts for OER by N2 plasma (Xu et al 2017 Nanotechnology 28 165402). This work has successfully demonstrated the simple N2 plasma treatment to be a powerful technique to introduce the nitrogen doping and nanoporous structure in the bulk materials, enhancing the performance of electrochemical catalysis. Based on this study, more future work on developing highly porous non-precious metal-based materials with good conductivity would be promising for energy storage and conversion.

  15. Noria: A Highly Xe-Selective Nanoporous Organic Solid

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Rahul S. [Department of Chemistry, University of Missouri, Columbia Missouri 65211 United States; Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland Washington 99352 United States; Banerjee, Debasis [Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland Washington 99352 United States; Simon, Cory M. [Department of Chemical & Biomolecular Engineering, University of California, Berkeley, Berkeley California 94720 United States; Atwood, Jerry L. [Department of Chemistry, University of Missouri, Columbia Missouri 65211 United States; Thallapally, Praveen K. [Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland Washington 99352 United States

    2016-07-05

    The successful mass-implementation of nuclear energy requires reprocessing of used nuclear fuel (UNF) to mitigate harmful radioactive waste. Volatile radionuclides such as Xe and Kr evolve into off-gas streams of UNF reprocessing facilities in parts per million concentrations; their capture and successive safe handing is essential from a regulatory point of view. As radioactive Xe has a short half-life, this captured Xe could be sold in the chemical market. Energy-intensive, expensive, and hazardous cryogenic distillation is the current benchmark process to capture and separate radioactive Xe and Kr from air. Thus, a cost-effective, alternative technology for the separation of Xe and Kr and their capture from air is of significant importance. Thus far, nanoporous materials, such as aluminosilicate zeolites, metal organic frameworks (MOFs) and porous organic molecules have shown promise for an adsorption-based separation process at room temperature. Herein, we report the selective Xe uptake in a crystalline porous organic oligomeric molecule, noria, and its structural analogue, PgC-noria, under ambient conditions. The selectivity of noria towards Xe arises from its tailored pore size and small cavities, which allows a directed non-bonding interaction of Xe atoms with a large number of carbon atoms of the noria molecular wheel in a confined space.

  16. Optimal design of graphene nanopores for seawater desalination.

    Science.gov (United States)

    Li, Zhongwu; Qiu, Yinghua; Li, Kun; Sha, Jingjie; Li, Tie; Chen, Yunfei

    2018-01-07

    Extensive molecular dynamics simulations are employed to optimize nanopore size and surface charge density in order to obtain high ionic selectivity and high water throughput for seawater desalination systems. It is demonstrated that with the help of surface charge exclusion, nanopores with diameter as large as 3.5 nm still have high ionic selectivity. The mechanism of the salt rejection in a surface-charged nanopore is mainly attributed to the ion concentration difference between the cations and anions induced by the surface charges. Increasing surface charge density is beneficial to enhance ionic selectivity. However, there exists a critical value for the surface charge density. Once the surface charge density exceeds the critical value, charge inversion occurs inside a nanopore. Further increasing the surface charge density will deteriorate the ionic selectivity because the highly charged nanopore surface will allow more coions to enter the nanopore in order to keep the whole system in charge neutrality. Besides the surface charge density, the nanopore length also affects the ionic selectivity. Based on our systematic simulations, nanopores with surface charge density between -0.09 C/m2 and -0.12 C/m2, diameters smaller than 3.5 nm, and membrane thickness ranging between 8 and 10 graphene layers show an excellent performance for the ionic selectivity.

  17. Optimal design of graphene nanopores for seawater desalination

    Science.gov (United States)

    Li, Zhongwu; Qiu, Yinghua; Li, Kun; Sha, Jingjie; Li, Tie; Chen, Yunfei

    2018-01-01

    Extensive molecular dynamics simulations are employed to optimize nanopore size and surface charge density in order to obtain high ionic selectivity and high water throughput for seawater desalination systems. It is demonstrated that with the help of surface charge exclusion, nanopores with diameter as large as 3.5 nm still have high ionic selectivity. The mechanism of the salt rejection in a surface-charged nanopore is mainly attributed to the ion concentration difference between the cations and anions induced by the surface charges. Increasing surface charge density is beneficial to enhance ionic selectivity. However, there exists a critical value for the surface charge density. Once the surface charge density exceeds the critical value, charge inversion occurs inside a nanopore. Further increasing the surface charge density will deteriorate the ionic selectivity because the highly charged nanopore surface will allow more coions to enter the nanopore in order to keep the whole system in charge neutrality. Besides the surface charge density, the nanopore length also affects the ionic selectivity. Based on our systematic simulations, nanopores with surface charge density between -0.09 C/m2 and -0.12 C/m2, diameters smaller than 3.5 nm, and membrane thickness ranging between 8 and 10 graphene layers show an excellent performance for the ionic selectivity.

  18. Protein transport through a narrow solid-state nanopore at high voltage: experiments and theory.

    Science.gov (United States)

    Cressiot, Benjamin; Oukhaled, Abdelghani; Patriarche, Gilles; Pastoriza-Gallego, Manuela; Betton, Jean-Michel; Auvray, Loïc; Muthukumar, Murugappan; Bacri, Laurent; Pelta, Juan

    2012-07-24

    We report experimentally the transport of an unfolded protein through a narrow solid-state nanopore of 3 nm diameter as a function of applied voltage. The random coil polypeptide chain is larger than the nanopore. The event frequency dependency of current blockades from 200 to 750 mV follows a van't Hoff-Arrhenius law due to the confinement of the unfolded chain. The protein is an extended conformation inside the pore at high voltage. We observe that the protein dwell time decreases exponentially at medium voltage and is inversely proportional to voltage for higher values. This is consistent with the translocation mechanism where the protein is confined in the pore, creating an entropic barrier, followed by electrophoretic transport. We compare these results to our previous work with a larger pore of 20 nm diameter. Our data suggest that electro-osmotic flow and protein adsorption on the narrowest nanopore wall are minimized. We discuss the experimental data obtained as compared with recent theory for the polyelectrolyte translocation process. This theory reproduces clearly the experimental crossover between the entropic barrier regime with medium voltage and the electrophoretic regime with higher voltage.

  19. Nanoporous AAO: A platform for regular heterogeneous nanostructures and energy storage devices

    Science.gov (United States)

    Perez, Israel

    Nanoporous anodic aluminum oxide (AAO) has vast implications as a tool for nanoscience research and as a nanostructure in which nanoscale devices can be fabricated because of its regular and ordered nanopores. Self-assembly plays a critical role in pore ordering, causing nanopores to grow parallel with one another in high density. The mild electrochemical conditions in which porous AAO grows along with its relatively cheap starting materials makes this nanomaterial a cost effective alternative to advanced photolithography techniques for forming high surface area nanostructures over large areas. In this research, atomic layer deposition (ALD) was used to deposit conformal films within in nanoporous AAO with hopes to (1) develop methodologies to characterize ALD depositions within its high aspect ratio nanopores and (2) to better understand how to use nanoporous AAO templates as a scaffold for energy devices, specifically Metal-Insulator-Metal (MIM) capacitors. Using the nanotube template synthesis method, ALD films were deposited onto nanoporous AAO, later removing the films deposited within the templates nanopores for characterization in TEM. This nanotube metrology characterization involves first obtaining images of full length ALD-AAO nanotubes, and then measuring wall thickness as a function of depth within the nanopore. MIM nanocapacitors were also constructed in vertical AAO nanopores by deposition of multilayer ALD films. MIM stacks were patterned into micro-scale capacitors for electrical characterization.

  20. 10 nm Diameter Periodic Holes On The Barrier Layer Of Hexagonally Ordered Nanoporous Alumina Produced By Grazing Ar+ Milling

    Science.gov (United States)

    Xu, Tao; Metzger, Robert M.

    2002-03-01

    Long-term anodization of aluminum provides a hexagonally ordered array of nanopores with very uniform pore diameters between 30 and 50 nm and pore spacings of 80 to 100 nm within a matrix of amorphous aluminum oxide [1]. However, one often desires smaller diameters. Because the bottom of each pore is U-shaped, we can use this geometrical feature and gradually open the U-shaped bottom cap of the alumina nanochannel by controlled grazing-angle Ar+ ion milling, and thus form pore apertures as small as 10 nm in diameter [2]. Such smaller hole diameters may be useful for exposing sub-10 nm diameter ordered cobalt particles as catalysts for preparation of ordered array of single wall carbon nanotubes, for organizing nano-scale electrodes for molecular electronic devices, and as a pattern transfer mask. Supported in part by NSF-DMR-0095215 ==== [1] F. Li, L. Zhang, and R. M. Metzger, Chem. Mater. 10(9): 2470-2480 (1998). [2] T. Xu, G. Zangari, and R. M. Metzger, Nanoletters, accepted and in press.

  1. Selective growth and piezoelectric properties of highly ordered arrays of vertical ZnO nanowires on ultrathin alumina membranes

    Science.gov (United States)

    Wen, Liaoyong; Shao, Zhengzheng; Fang, Yaoguo; Wong, Kin Mun; Lei, Yong; Bian, Lifeng; Wilde, Gerhard

    2010-08-01

    A well controlled and cost effective method of fabricating highly ordered arrays of vertical zinc oxide (ZnO) nanowires or nanopores is demonstrated where an ultrathin alumina membrane (UTAM) itself is utilized as a substrate for the selective growth of the ordered arrays. A thin film of gold was thermally evaporated on the UTAM followed by the growth of highly regular ZnO nanowires using chemical vapor deposition (CVD). Alternatively, highly ordered ZnO nanopores arrays were also grown by CVD on the bare UTAM. Additionally, piezoelectric currents were generated from the ZnO nanowires during the conductive atomic force microscopy probe tip scan across the array.

  2. Nanopore fabricated in pyramidal HfO2 film by dielectric breakdown method

    Science.gov (United States)

    Wang, Yifan; Chen, Qi; Deng, Tao; Liu, Zewen

    2017-10-01

    The dielectric breakdown method provides an innovative solution to fabricate solid-state nanopores on insulating films. A nanopore generation event via this method is considered to be caused by random charged traps (i.e., structural defects) and high electric fields in the membrane. Thus, the position and number of nanopores on planar films prepared by the dielectric breakdown method is hard to control. In this paper, we propose to fabricate nanopores on pyramidal HfO2 films (10-nm and 15-nm-thick) to improve the ability to control the location and number during the fabrication process. Since the electric field intensity gets enhanced at the corners of the pyramid-shaped film, the probability of nanopore occurrence at vertex and edge areas increases. This priority of appearance provides us chance to control the location and number of nanopores by monitoring a sudden irreversible discrete increase in current. The experimental results showed that the probability of nanopore occurrence decreases in an order from the vertex area, the edge area to the side face area. The sizes of nanopores ranging from 30 nm to 10 nm were obtained. Nanopores fabricated on the pyramid-shaped HfO2 film also showed an obvious ion current rectification characteristic, which might improve the nanopore performance as a biomolecule sequencing platform.

  3. Nanoporous Hybrid Electrolytes for High-Energy Batteries Based on Reactive Metal Anodes

    KAUST Repository

    Tu, Zhengyuan

    2017-01-06

    Successful strategies for stabilizing electrodeposition of reactive metals, including lithium, sodium, and aluminum are a requirement for safe, high-energy electrochemical storage technologies that utilize these metals as anodes. Unstable deposition produces high-surface area dendritic structures at the anode/electrolyte interface, which causes premature cell failure by complex physical and chemical processes that have presented formidable barriers to progress. Here, it is reported that hybrid electrolytes created by infusing conventional liquid electrolytes into nanoporous membranes provide exceptional ability to stabilize Li. Electrochemical cells based on γ-Al2O3 ceramics with pore diameters below a cut-off value above 200 nm exhibit long-term stability even at a current density of 3 mA cm−2. The effect is not limited to ceramics; similar large enhancements in stability are observed for polypropylene membranes with less monodisperse pores below 450 nm. These findings are critically assessed using theories for ion rectification and electrodeposition reactions in porous solids and show that the source of stable electrodeposition in nanoporous electrolytes is fundamental.

  4. Nanoporous Hybrid Electrolytes for High-Energy Batteries Based on Reactive Metal Anodes

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Zhengyuan [Department of Materials Science and Engineering, Cornell University, Ithaca NY 14850 USA; Zachman, Michael J. [School of Applied and Engineering Physics, Cornell University, Ithaca NY 14850 USA; Choudhury, Snehashis [School of Chemical Engineering and Biomolecular Engineering, Cornell University, Ithaca NY 14850 USA; Wei, Shuya [School of Chemical Engineering and Biomolecular Engineering, Cornell University, Ithaca NY 14850 USA; Ma, Lin [Department of Materials Science and Engineering, Cornell University, Ithaca NY 14850 USA; Yang, Yuan [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden CO 80401 USA; Kourkoutis, Lena F. [School of Applied and Engineering Physics, Cornell University, Ithaca NY 14850 USA; Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca NY 14853 USA; Archer, Lynden A. [Department of Materials Science and Engineering, Cornell University, Ithaca NY 14850 USA; School of Chemical Engineering and Biomolecular Engineering, Cornell University, Ithaca NY 14850 USA

    2017-01-06

    Successful strategies for stabilizing electrodeposition of reactive metals, including lithium, sodium, and aluminum are a requirement for safe, high-energy electrochemical storage technologies that utilize these metals as anodes. Unstable deposition produces high-surface area dendritic structures at the anode/electrolyte interface, which causes premature cell failure by complex physical and chemical processes that have presented formidable barriers to progress. Here, it is reported that hybrid electrolytes created by infusing conventional liquid electrolytes into nanoporous membranes provide exceptional ability to stabilize Li. Electrochemical cells based on γ-Al2O3 ceramics with pore diameters below a cut-off value above 200 nm exhibit long-term stability even at a current density of 3 mA cm-2. The effect is not limited to ceramics; similar large enhancements in stability are observed for polypropylene membranes with less monodisperse pores below 450 nm. These findings are critically assessed using theories for ion rectification and electrodeposition reactions in porous solids and show that the source of stable electrodeposition in nanoporous electrolytes is fundamental.

  5. Aligned nano-porous microwave exfoliated graphite oxide ionic actuators with high strain and elastic energy density.

    Science.gov (United States)

    Ghaffari, M; Kinsman, W; Zhou, Y; Murali, S; Burlingame, Q; Lin, M; Ruoff, R S; Zhang, Q M

    2013-11-20

    A high-density aligned nanoporous activated microwave exfoliated graphite oxide (aMEGO) ionic actuator is studied. Before applying an external electric field, the cations and anions are randomly distributed in the composite. After applying the electric field, ions ingress in between the aligned aMEGO sheets through the nanopores to compensate the charges on the electrodes, resulting in the separation of neighboring sheets and unidirectional electro actuation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J. Douglas [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical and Biological Engineering; Wolden, Colin A. [Colorado School of Mines, Golden, CO (United States)

    2013-09-30

    Colorado School of Mines (CSM) developed high temperature, hydrogen permeable membranes that contain no platinum group metals with the goal of separating hydrogen from gas mixtures representative of gasification of carbon feedstocks such as coal or biomass in order to meet DOE NETL 2015 hydrogen membrane performance targets. We employed a dual synthesis strategy centered on transition metal carbides. In the first approach, novel, high temperature, surface diffusion membranes based on nanoporous Mo2C were fabricated on ceramic supports. These were produced in a two step process that consisted of molybdenum oxide deposition followed by thermal carburization. Our best Mo2C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft2 at a feed pressure of only 20 psig. The highest H2/N2 selectivity obtained with this approach was 4.9. A transport model using “dusty gas” theory was derived to describe the hydrogen transport in the Mo2C coated, surface diffusion membranes. The second class of membranes developed were dense metal foils of BCC metals such as vanadium coated with thin (< 60 nm) Mo2C catalyst layers. We have fabricated a Mo2C/V composite membrane that in pure gas testing delivered a H2 flux of 238 SCFH/ft2 at 600 °C and 100 psig, with no detectable He permeance. This exceeds the 2010 DOE Target flux. This flux is 2.8 times that of pure Pd at the same membrane thickness and test conditions and over 79% of the 2015 flux target. In mixed gas testing we achieved a permeate purity of ≥99.99%, satisfying the permeate purity milestone, but the hydrogen permeance was low, ~0.2 SCFH/ft2.psi. However, during testing of a Mo2C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft2.psi was obtained which was stable during the entire test, meeting the permeance associated with

  7. Synthesize and characterization of graphene nanosheets with high surface area and nano-porous structure

    Energy Technology Data Exchange (ETDEWEB)

    Jabari Seresht, Razieh [Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of); Jahanshahi, Mohsen, E-mail: mjahan@nit.ac.ir [Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of); Rashidi, Alimorad [Nanotechnology Research Center, Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of); Ghoreyshi, Ali Asghar [Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of)

    2013-07-01

    A few-layer graphene was obtained by the expansion and exfoliation of water-intercalated graphene oxide via heat treatment in nitrogen environment in the temperature range of 200–1000 °C. Graphene which was synthesized at 800 °C (GT800) had a higher quality than other temperatures. This graphene has a high specific surface area (560.6 m{sup 2} g{sup −1}) and nano-porous structure. However, as for the purpose of comparison, graphene was synthesized with a colloidal suspension of exfoliated graphene oxide sheets in water with hydrazine hydrate in various reaction times (12, 24 and 36 h). This method has obtained a six-layer graphene and graphene that was synthesized during 24 h reaction with hydrazine hydrate (GC24) had a higher quality in comparison with the other products. The GC24 had 195.97 m{sup 2} g{sup −1} specific surface area and nano-porous structure. The as-synthesized graphene were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) as well as BET measurements. The results demonstrated that this low-cost method for few-layer grapheme, e.g. three-layers, fabrication is reliable and promising.

  8. Artificial pinning centers using the barrier layer of ordered nanoporous alumina templates

    DEFF Research Database (Denmark)

    Hallet, X.; Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.

    2009-01-01

    The barrier layer of self-ordered anodized aluminium oxide, which is grown from an aluminium foil, has been revealed by a selective chemical etching of the remaining aluminium. The surface obtained in this way consists of a triangular lattice of bumps with 100nm spacing, and heights of approximat......The barrier layer of self-ordered anodized aluminium oxide, which is grown from an aluminium foil, has been revealed by a selective chemical etching of the remaining aluminium. The surface obtained in this way consists of a triangular lattice of bumps with 100nm spacing, and heights...

  9. Nanoporous CuS nano-hollow spheres as advanced material for high-performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, Hamid [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Moosavifard, Seyyed Ebrahim, E-mail: info_seyyed@yahoo.com [Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Elyasi, Saeed [Department of Chemical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Shahraki, Mohammad [Department of Chemistry, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of)

    2017-02-01

    Highlights: • Nanoporous CuS nano-hollow spheres were synthesized by a facile method. • Nano-hollow spheres have a large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). • Such unique structures exhibit excellent electrochemical properties for high-performance SCs. - Abstract: Due to unique advantages, the development of high-performance supercapacitors has stimulated a great deal of scientific research over the past decade. The electrochemical performance of a supercapacitor is strongly affected by the surface and structural properties of its electrode materials. Herein, we report a facile synthesis of high-performance supercapacitor electrode material based on CuS nano-hollow spheres with nanoporous structures, large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). This interesting electrode structure plays a key role in providing more active sites for electrochemical reactions, short ion and electron diffusion pathways and facilitated ion transport. The CuS nano-hollow spheres electrode exhibits excellent electrochemical performance including a maximum specific capacitance of 948 F g{sup −1} at 1 A g{sup −1}, significant rate capability of 46% capacitance retention at a high current density of 50 A g{sup −1}, and outstanding long-term cycling stability at various current densities. This work not only demonstrates the promising potential of the CuS-NHS electrodes for application in high-performance supercapacitors, but also sheds a new light on the metal sulfides design philosophy.

  10. Luminescence properties of YVO4:Eu nanocrystals in nanoporous high-silica glass

    Science.gov (United States)

    Fan, Bin; Qi, Shimei; Zhao, Wenyu

    2018-02-01

    A feasible method was used to synthesize YVO4:Eu nanocrystals in nanoporous high-silica glass (YVOE-HSG). High-resolution transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy were used to investigate its morphology, structure, and optical properties, respectively. The Eu ions were introduced as luminescence centers into the sample YVOE-HSG. Under 291 nm excitation, the samples exhibit the characteristic transitions of Eu3+ and Eu2+. With the increase of Eu3+ doping concentration, the positions of main excitation peaks shift to long waves. The reduction of Eu3+ to Eu2+ is observed, and the chromaticity coordinates (x, y) can move from the red light to cool white and then to blue light. The efficient energy transfer from VO43- to Eu3+ and Eu2+ is confirmed. Results indicated that the sample has potential application in white light-emitting diodes under UV excitation.

  11. Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Duc Hoa

    2015-01-01

    Full Text Available Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas sensor applications are introduced. The advantages of meso-/nanoporous metal oxides are also presented, taking into account the crystallinity and ordered/disordered porous structures. Second, the synthesis methods of meso-/nanoporous metal oxides including the soft-template, hard-template, and temple-free methods are introduced, in which the advantages and disadvantages of each synthetic method are figured out. Third, the applications of meso-/nanoporous metal oxides as gas sensors are presented. The gas nanosensors are designed based on meso-/nanoporous metal oxides for effective detection of toxic gases. The sensitivity, selectivity, and stability of the meso-/nanoporous gas nanosensors are also discussed. Finally, some conclusions and an outlook are presented.

  12. High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes

    CERN Document Server

    Chen, Wei; Zhang, Qiang; Fan, Zhongli; Huang, Kuo-Wei; Zhang, Xixiang; Lai, Zhiping; Sheng, Ping

    2016-01-01

    Nanoporous carbon composite membranes, comprising a layer of porous carbon fiber structures with an average channel width of 30-60 nm grown on a porous ceramic substrate, are found to exhibit robust desalination effect with high freshwater flux. In three different membrane processes of vacuum membrane distillation, reverse osmosis and forward osmosis, the carbon composite membrane showed 100% salt rejection with 3.5 to 20 times higher freshwater flux compared to existing polymeric membranes. Thermal accounting experiments found that at least 80% of the freshwater pass through the carbon composite membrane with no phase change. Molecular dynamics simulations revealed a unique salt rejection mechanism. When seawater is interfaced with either vapor or the surface of carbon, one to three interfacial atomic layers contain no salt ions. Below the liquid entry pressure, the salt solution is stopped at the openings to the porous channels and forms a meniscus, while the surface layer of freshwater can feed the surface...

  13. High performance asymmetric V2O5-SnO2 nanopore battery by atomic layer deposition.

    Science.gov (United States)

    Liu, Chanyuan; Kim, Nam; Rubloff, Gary W; Lee, Sang Bok

    2017-08-17

    Here we report the high performance and cyclability of an asymmetric full cell nanopore battery, comprised of V2O5 as the cathode and prelithiated SnO2 as the anode, with integrated nanotubular Pt current collectors underneath each nanotubular storage electrode, confined within an anodized aluminium oxide (AAO) nanopore. Enabled by atomic layer deposition (ALD), this coaxial nanotube full cell is fully confined within a high aspect ratio nanopore (150 nm in diameter, 50 μm in length), with an ultra-small volume of about 1 fL. By controlling the amount of lithium ion prelithiated into the SnO2 anode, we can tune the full cell output voltage in the range of 0.3 V to 3 V. When tested as a massively parallel device (∼2 billion cm(-2)), this asymmetric nanopore battery array displays exceptional rate performance and cyclability: when cycled between 1 V and 3 V, capacity retention at the 200C rate is ∼73% of that at 1C, and at 25C rate only 2% capacity loss occurs after more than 500 charge/discharge cycles. With the increased full cell output potential, the asymmetric V2O5-SnO2 nanopore battery shows significantly improved energy and power density over the previously reported symmetric cell, 4.6 times higher volumetric energy and 5.2 times higher power density - an even more promising indication that controlled nanostructure designs employing nanoconfined environments with large electrode surface areas present promising directions for future battery technology.

  14. Sulfur-doped nanoporous carbon spheres with ultrahigh specific surface area and high electrochemical activity for supercapacitor

    Science.gov (United States)

    Liu, Simin; Cai, Yijin; Zhao, Xiao; Liang, Yeru; Zheng, Mingtao; Hu, Hang; Dong, Hanwu; Jiang, Sanping; Liu, Yingliang; Xiao, Yong

    2017-08-01

    Development of facile and scalable synthesis process for the fabrication of nanoporous carbon materials with large specific surface areas, well-defined nanostructure, and high electrochemical activity is critical for the high performance energy storage applications. The key issue is the dedicated balance between the ultrahigh surface area and highly porous but interconnected nanostructure. Here, we demonstrate the fabrication of new sulfur doped nanoporous carbon sphere (S-NCS) with the ultrahigh surface area up to 3357 m2 g-1 via a high-temperature hydrothermal carbonization and subsequent KOH activation process. The as-prepared S-NCS which integrates the advantages of ultrahigh porous structure, well-defined nanospherical and modification of heteroatom displays excellent electrochemical performance. The best performance is obtained on S-NCS prepared by the hydrothermal carbonization of sublimed sulfur and glucose, S-NCS-4, reaching a high specific capacitance (405 F g-1 at a current density of 0.5 A g-1) and outstanding cycle stability. Moreover, the symmetric supercapacitor is assembled by S-NCS-4 displays a superior energy density of 53.5 Wh kg-1 at the power density of 74.2 W kg-1 in 1.0 M LiPF6 EC/DEC. The synthesis method is simple and scalable, providing a new route to prepare highly porous and heteroatom-doped nanoporous carbon spheres for high performance energy storage applications.

  15. Preparation of 3D nanoporous copper-supported cuprous oxide for high-performance lithium ion battery anodes.

    Science.gov (United States)

    Liu, Dequan; Yang, Zhibo; Wang, Peng; Li, Fei; Wang, Desheng; He, Deyan

    2013-03-07

    Three-dimensional (3D) nanoporous architectures can provide efficient and rapid pathways for Li-ion and electron transport as well as short solid-state diffusion lengths in lithium ion batteries (LIBs). In this work, 3D nanoporous copper-supported cuprous oxide was successfully fabricated by low-cost selective etching of an electron-beam melted Cu(50)Al(50) alloy and subsequent in situ thermal oxidation. The architecture was used as an anode in lithium ion batteries. In the first cycle, the sample delivered an extremely high lithium storage capacity of about 2.35 mA h cm(-2). A high reversible capacity of 1.45 mA h cm(-2) was achieved after 120 cycles. This work develops a promising approach to building reliable 3D nanostructured electrodes for high-performance lithium ion batteries.

  16. On the specific surface area of nanoporous materials

    NARCIS (Netherlands)

    Detsi, E.; De Jong, E.; Zinchenko, A.; Vukovic, Z.; Vukovic, I.; Punzhin, S.; Loos, K.; ten Brinke, G.; De Raedt, H. A.; Onck, P. R.; De Hosson, J. T. M.

    2011-01-01

    A proper quantification of the specific surface area of nanoporous materials is necessary for a better understanding of the properties that are affected by the high surface-area-to-volume ratio of nanoporous metals, nanoporous polymers and nanoporous ceramics. In this paper we derive an analytical

  17. Nanoporous PdNi/C electrocatalyst prepared by dealloying high-Ni-content PdNi alloy for formic acid oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Wang, Hui; Wang, Rongfang [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Ji, Shan [South African Institute for Advanced Materials Chemistry, University of the Western Cape, Cape Town 7535 (South Africa)

    2012-12-15

    To improve the electrochemical performance of Pd-based catalysts for formic acid oxidation, a carbon supported nanoporous PdNi catalyst is prepared by dealloying high-Ni-content PdNi alloy nanoparticles in acid solution. The structure of nanoporous PdNi/C catalyst is characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The electrocatalytic results show that the activity of the nanoporous PdNi/C catalyst is higher than that of nonporous Pd/C catalyst. The results demonstrate that the carbon-supported nanoporous PdNi catalyst has a potential for application in direct formic acid fuel cells. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Enabling Technologies for High-Throughput Screening of Nano-Porous Materials: Collaboration with the Nanoporous Materials Genome Center

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Jordan [Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry

    2016-01-21

    The overarching goal of this research was to develop new methodologies to enable the accurate and efficient modeling of complex materials using computer simulations. Using inter-molecular interaction energies calculated via an accurate but computationally expensive approach (symmetry-adapted perturbation theory), we parameterized efficient next-generation “force fields” to utilize in subsequent simulations. Since the resulting force fields incorporate much of the relevant physics of inter-molecular interactions, they consequently exhibit high transferability from one material to another. This transferability enables the modeling of a wide range of novel materials without additional computational cost. While this approach is quite general, a particular emphasis of this research involved applications to so-called “metal-organic framework”(MOF) materials relevant to energy-intensive gas separations. We focused specifically on CO2/N2 selectivity, which is a key metric for post combustion CO2 capture efforts at coal-fired power plants. The gas adsorption capacities and selectivity of the MOFs can be tailored via careful functionalization. We have demonstrated that our force fields exhibit predictive accuracy for a wide variety of functionalized MOFs, thus opening the door for the computational design of “tailored” materials for particular separations. Finally, we have also demonstrated the importance of accounting for the presence of reactive contaminant species when evaluating the performance of MOFs in practical applications.

  19. Vertically standing nanoporous Al-Ag zig-zag silver nanorod arrays for highly active SERS substrates.

    Science.gov (United States)

    Rajput, Ankita; Kumar, Samir; Singh, Jitendra P

    2017-10-09

    Surface enhanced Raman scattering (SERS) has emerged as a promising technique for chemical and biological sensing. "Hot spots" are the areas on noble metal nanostructures where light is highly concentrated into small volumes and enhances the local electromagnetic field near the metal nanostructures. These hot spots have been claimed to provide extraordinary enhancements to the SERS signal. Here, we report the fabrication of nanoporous zig-zag Ag nanostructures with built-in high density hot spots. The zig-zag Ag nanostructures were fabricated by glancing angle deposition of Ag and Al, with Al deposited on the edges of the zig-zag structure during growth. A 2.5 wt% HCl solution was used for etching Al from the Ag-Al zig-zag structure. The etching process produced intra-particle gaps by leaching less stable Al from fully alloyed Al-Ag nanostructures. This step of mild acid etching (2.5% v/v HCl for 45 min) allowed the formation of Raman hot spots on the elbows of zig-zag nanorods while maintaining the zig-zag morphology of highly active Ag nanostructures. A high enhancement factor of ∼106 was observed on nanoporous zig-zag Ag nanostructures obtained by de-alloying, making them very appealing as Raman sensors. The role played by nanogap hot spots in Ag zig-zag nanostructures towards SERS enhancement is modelled by using finite difference time domain (FDTD) simulations.

  20. Fabrication and Characterization of High-Crystalline Nanoporous ZnO Thin Films by Modified Thermal Evaporation System

    Science.gov (United States)

    Islam, M. S.; Hossain, M. F.; Razzak, S. M. A.; Haque, M. M.; Saha, D. K.

    2016-05-01

    The aim of this work is to fabricate high-crystalline nanoporous zinc oxide (ZnO) thin films by a modified thermal evaporation system. First, zinc thin films have been deposited on bare glass substrate by the modified thermal evaporation system with pressure of 0.05mbar, source-substrate distance of 3cm and source temperature 700∘C. Then, high-crystalline ZnO thin film is obtained by annealing at 500∘C for 2h in atmosphere. The prepared ZnO films are characterized with various deposition times of 10min and 20min. The structural property was investigated by X-ray diffractometer (XRD). The optical bandgap and absorbance/transmittance of these films are examined by ultraviolet/visible spectrophotometer. The surface morphological property has been observed by scanning electron microscope (SEM). ZnO films have showed uniform nanoporous surface with high-crystalline hexagonal wurtzite structure. The ZnO films prepared with 20min has excitation absorption-edge at 369nm, which is blueshifted with respect to the bulk absorption-edge appearing at 380nm. The gap energy of ZnO film is decreased from 3.14eV to 3.09eV with increase of the deposition time, which can enhance the excitation of ZnO films by the near visible light, and is suitable for the application of photocatalyst of waste water cleaning and polluted air purification.

  1. Application of highly portable MinION nanopore sequencing technology for the monitoring of nosocomial tuberculosis infection

    Directory of Open Access Journals (Sweden)

    Matthew Bates

    2016-01-01

    Full Text Available Referral hospitals in sub-Saharan Africa concentrate large numbers of tuberculosis (TB and multidrug-resistant TB (MDR-TB patients, failed by community TB services. We have previously shown, from enhanced screening and through autopsy studies, a significant burden of missed TB infections at the University Teaching Hospital, Lusaka, Zambia, with many patients dying or being discharged without treatment. With minimal TB isolation facilities and minimal political will to invest in broader screening and isolation, the risk of nosocomial transmission is likely to be extremely high. Studies from other hospitals in low burden settings and in South Africa have shown that next generation sequencing (NGS is a very powerful tool for rapidly sequencing whole TB genomes and comparing them to confirm or rule out nosocomial transmission. The established platforms for NGS analysis, such as Illumina, are very expensive, immobile, and require regular maintenance, making them a costly inclusion on a research proposal or programmatic intervention grant in Africa. MinION nanopore sequencing has changed the NGS landscape with cheap portable sequencers, rapid simple library preparation (15 min, and automated real-time analysis tools. The application of highly portable MinION nanopore sequencing technology for the monitoring of nosocomial TB infection will be discussed. Preliminary data from our pediatric pneumonia study will demonstrate the detection of TB in induced sputum from children admitted to the University Teaching Hospital.

  2. Application of highly portable MinION nanopore sequencing technology for the monitoring of nosocomial tuberculosis infection.

    Science.gov (United States)

    Bates, Matthew; Polepole, Pascal; Kapata, Nathan; Loose, Matt; O'Grady, Justin

    2016-12-01

    Referral hospitals in sub-Saharan Africa concentrate large numbers of tuberculosis (TB) and multidrug-resistant TB (MDR-TB) patients, failed by community TB services. We have previously shown, from enhanced screening and through autopsy studies, a significant burden of missed TB infections at the University Teaching Hospital, Lusaka, Zambia, with many patients dying or being discharged without treatment. With minimal TB isolation facilities and minimal political will to invest in broader screening and isolation, the risk of nosocomial transmission is likely to be extremely high. Studies from other hospitals in low burden settings and in South Africa have shown that next generation sequencing (NGS) is a very powerful tool for rapidly sequencing whole TB genomes and comparing them to confirm or rule out nosocomial transmission. The established platforms for NGS analysis, such as Illumina, are very expensive, immobile, and require regular maintenance, making them a costly inclusion on a research proposal or programmatic intervention grant in Africa. MinION nanopore sequencing has changed the NGS landscape with cheap portable sequencers, rapid simple library preparation (15min), and automated real-time analysis tools. The application of highly portable MinION nanopore sequencing technology for the monitoring of nosocomial TB infection will be discussed. Preliminary data from our pediatric pneumonia study will demonstrate the detection of TB in induced sputum from children admitted to the University Teaching Hospital. Copyright © 2016.

  3. Integrated Solid/Nanoporous Copper/Oxide Hybrid Bulk Electrodes for High-performance Lithium-Ion Batteries

    Science.gov (United States)

    Hou, Chao; Lang, Xing-You; Han, Gao-Feng; Li, Ying-Qi; Zhao, Lei; Wen, Zi; Zhu, Yong-Fu; Zhao, Ming; Li, Jian-Chen; Lian, Jian-She; Jiang, Qing

    2013-10-01

    Nanoarchitectured electroactive materials can boost rates of Li insertion/extraction, showing genuine potential to increase power output of Li-ion batteries. However, electrodes assembled with low-dimensional nanostructured transition metal oxides by conventional approach suffer from dramatic reductions in energy capacities owing to sluggish ion and electron transport kinetics. Here we report that flexible bulk electrodes, made of three-dimensional bicontinuous nanoporous Cu/MnO2 hybrid and seamlessly integrated with Cu solid current collector, substantially optimizes Li storage behavior of the constituent MnO2. As a result of the unique integration of solid/nanoporous hybrid architecture that simultaneously enhances the electron transport of MnO2, facilitates fast ion diffusion and accommodates large volume changes on Li insertion/extraction of MnO2, the supported MnO2 exhibits a stable capacity of as high as ~1100 mA h g-1 for 1000 cycles, and ultrahigh charge/discharge rates. It makes the environmentally friendly and low-cost electrode as a promising anode for high-performance Li-ion battery applications.

  4. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  5. High-order epistasis shapes evolutionary trajectories.

    OpenAIRE

    Sailer, Zachary R.; Harms, Michael J.

    2017-01-01

    High-order epistasis-where the effect of a mutation is determined by interactions with two or more other mutations-makes small, but detectable, contributions to genotype-fitness maps. While epistasis between pairs of mutations is known to be an important determinant of evolutionary trajectories, the evolutionary consequences of high-order epistasis remain poorly understood. To determine the effect of high-order epistasis on evolutionary trajectories, we computationally removed high-order epis...

  6. High-order epistasis shapes evolutionary trajectories

    OpenAIRE

    Sailer, Zachary R.

    2017-01-01

    High-order epistasis?where the effect of a mutation is determined by interactions with two or more other mutations?makes small, but detectable, contributions to genotype-fitness maps. While epistasis between pairs of mutations is known to be an important determinant of evolutionary trajectories, the evolutionary consequences of high-order epistasis remain poorly understood. To determine the effect of high-order epistasis on evolutionary trajectories, we computationally removed high-order epis...

  7. Effects of bonding temperature on microstructure, fracture behavior and joint strength of Ag nanoporous bonding for high temperature die attach

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min-Su, E-mail: mskim927@gmail.com [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Nishikawa, Hiroshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2015-10-01

    Ag nanoparticle sintering has received much attention as an alternative joining method to lead-based soldering for high temperature electronic applications. However, there are still certain issues with this method, such as difficulties of in controlling the joining layer thickness and the occurrence of unexpected voids resulting from solvent evaporation. In this study, the effect of bonding temperature (200–400 °C) and environment (air and N{sub 2}) on the joint strength of Ag nanoporous bonding (NPB) on electroless nickel/immersion gold finished Cu disks was investigated. A nanoporous Ag sheet fabricated using dealloying method from an Al–Ag precursor was adopted as the insert material. The NPB was conducted at various temperatures (200–400 °C) for 30 min at a pressure of 20 MPa in both air and N{sub 2} environments. The joint strength of NPB was closely related with the microstructure of the Ag layer and the fracture mode of the joint, and increased with increasing bonding temperature through the formation of strong interface and a coarsened Ag layer. The effect of the bonding environment was not significant, except in the case of bonding temperature of 400 °C.

  8. Design of templated nanoporous carbon electrode materials with substantial high specific surface area for simultaneous determination of biomolecules.

    Science.gov (United States)

    Zhou, Shenghai; Shi, Hongyan; Feng, Xun; Xue, Kaiwen; Song, Wenbo

    2013-04-15

    Nanoporous carbon materials have attracted significant interests in the design of electrodes for electrocatalysis and biosensors. Here, three templated nanoporous carbons (TNCs) materials with substantial different specific surface area were designed and synthesized by a nanocasting method, in which mesoporous silicates and acid were used as template and catalyst, respectively. The TNCs were then used as electrode materials for simultaneous detection of dopamine (DA), ascorbic acid (AA) and uric acid (UA) at physiological pH. The correlations between specific surface area, edge-plane defect sites in TNCs and their distinguishing ability towards AA, DA, and UA were investigated. For TNCs with substantial larger specific surface area and more defect sites, the oxidation peaks of AA, DA and UA were separated well and their oxidation currents increased remarkably. A highly sensitive electrochemical sensor for simultaneous detection of those biomolecules was achieved by designing TNCs1 with the largest specific surface area and the most defect sites as the electrode material. The sensitivity of AA, DA and UA at the sensor is 0.012, 4.031, 0.605 μA/μM respectively. Results suggest that TNCs1 is promising in biomolecules simultaneous detection. This work may also be valuable for scientists who search for excellent carbon materials for biosensing and electrocatalysis. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Ordered nanoporous silica as carriers for improved delivery of water insoluble drugs: a comparative study between three dimensional and two dimensional macroporous silica

    National Research Council Canada - National Science Library

    Wang, Ying; Zhao, Qinfu; Hu, Yanchen; Sun, Lizhang; Bai, Ling; Jiang, Tongying; Wang, Siling

    2013-01-01

    The goal of the present study was to compare the drug release properties and stability of the nanoporous silica with different pore architectures as a matrix for improved delivery of poorly soluble drugs...

  10. DNA origami nanopores.

    Science.gov (United States)

    Bell, Nicholas A W; Engst, Christian R; Ablay, Marc; Divitini, Giorgio; Ducati, Caterina; Liedl, Tim; Keyser, Ulrich F

    2012-01-11

    We demonstrate the assembly of functional hybrid nanopores for single molecule sensing by inserting DNA origami structures into solid-state nanopores. In our experiments, single artificial nanopores based on DNA origami are repeatedly inserted in and ejected from solid-state nanopores with diameters around 15 nm. We show that these hybrid nanopores can be employed for the detection of λ-DNA molecules. Our approach paves the way for future development of adaptable single-molecule nanopore sensors based on the combination of solid-state nanopores and DNA self-assembly. © 2011 American Chemical Society

  11. Water desalination with a single-layer MoS2 nanopore

    Science.gov (United States)

    Heiranian, Mohammad; Farimani, Amir Barati; Aluru, Narayana R.

    2015-01-01

    Efficient desalination of water continues to be a problem facing the society. Advances in nanotechnology have led to the development of a variety of nanoporous membranes for water purification. Here we show, by performing molecular dynamics simulations, that a nanopore in a single-layer molybdenum disulfide can effectively reject ions and allow transport of water at a high rate. More than 88% of ions are rejected by membranes having pore areas ranging from 20 to 60 Å2. Water flux is found to be two to five orders of magnitude greater than that of other known nanoporous membranes. Pore chemistry is shown to play a significant role in modulating the water flux. Pores with only molybdenum atoms on their edges lead to higher fluxes, which are ∼70% greater than that of graphene nanopores. These observations are explained by permeation coefficients, energy barriers, water density and velocity distributions in the pores. PMID:26465062

  12. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

    Science.gov (United States)

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-01

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

  13. High-Order Frequency-Locked Loops

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    In very recent years, some attempts for designing high-order frequency-locked loops (FLLs) have been made. Nevertheless, the advantages and disadvantages of these structures, particularly in comparison with a standard FLL and high-order phase-locked loops (PLLs), are rather unclear. This lack...... study, and its small-signal modeling, stability analysis, and parameter tuning are presented. Finally, to gain insight about advantages and disadvantages of high-order FLLs, a theoretical and experimental performance comparison between the designed second-order FLL and a standard FLL (first-order FLL...

  14. High Lithium Transference Number Electrolytes via Creation of 3-Dimensional, Charged, Nanoporous Networks from Dense Functionalized Nanoparticle Composites

    KAUST Repository

    Schaefer, Jennifer L.

    2013-03-26

    High lithium transference number, tLi+, electrolytes are desired for use in both lithium-ion and lithium metal rechargeable battery technologies. Historically, low tLi+ electrolytes have hindered device performance by allowing ion concentration gradients within the cell, leading to high internal resistances that ultimately limit cell lifetime, charging rates, and energy density. Herein, we report on the synthesis and electrochemical features of electrolytes based on nanoparticle salts designed to provide high tLi+. The salts are created by cofunctionalization of metal oxide nanoparticles with neutral organic ligands and tethered lithium salts. When dispersed in a conducting fluid such as tetraglyme, they spontaneously form a charged, nanoporous network of particles at moderate nanoparticle loadings. Modification of the tethered anion chemistry from -SO3 - to -SO3BF3 - is shown to enhance ionic conductivity of the electrolytes by facilitating ion pair dissociation. At a particle volume fraction of 0.15, the electrolyte exists as a self-supported, nanoporous gel with an optimum ionic conductivity of 10 -4 S/cm at room temperature. Galvanostatic polarization measurements on symmetric lithium metal cells containing the electrolyte show that the cell short circuit time, tSC, is inversely proportional to the square of the applied current density tSC ∼ J-2, consistent with previously predicted results for traditional polymer-in-salt electrolytes with low tLi+. Our findings suggest that electrolytes with tLi+ ≈ 1 and good ion-pair dissociation delay lithium dendrite nucleation and may lead to improved lithium plating in rechargeable batteries with metallic lithium anodes. © 2013 American Chemical Society.

  15. High-order epistasis shapes evolutionary trajectories.

    Science.gov (United States)

    Sailer, Zachary R; Harms, Michael J

    2017-05-01

    High-order epistasis-where the effect of a mutation is determined by interactions with two or more other mutations-makes small, but detectable, contributions to genotype-fitness maps. While epistasis between pairs of mutations is known to be an important determinant of evolutionary trajectories, the evolutionary consequences of high-order epistasis remain poorly understood. To determine the effect of high-order epistasis on evolutionary trajectories, we computationally removed high-order epistasis from experimental genotype-fitness maps containing all binary combinations of five mutations. We then compared trajectories through maps both with and without high-order epistasis. We found that high-order epistasis strongly shapes the accessibility and probability of evolutionary trajectories. A closer analysis revealed that the magnitude of epistasis, not its order, predicts is effects on evolutionary trajectories. We further find that high-order epistasis makes it impossible to predict evolutionary trajectories from the individual and paired effects of mutations. We therefore conclude that high-order epistasis profoundly shapes evolutionary trajectories through genotype-fitness maps.

  16. USE OF ATOMIC LAYER DEPOSITION OF FUNCTIONALIZATION OF NANOPOROUS BIOMATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Brigmon, R.; Narayan, R.; Adiga, S.; Pellin, M.; Curtiss, L.; Stafslien, S.; Chisholm, B.; Monteiro-Riviere, N.; Elam, J.

    2010-02-08

    Due to its chemical stability, uniform pore size, and high pore density, nanoporous alumina is being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. In recent work, we have examined the use of atomic layer deposition for coating the surfaces of nanoporous alumina membranes. Zinc oxide coatings were deposited on nanoporous alumina membranes using atomic layer deposition. The zinc oxide-coated nanoporous alumina membranes demonstrated antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that atomic layer deposition is an attractive technique for modifying the surfaces of nanoporous alumina membranes and other nanostructured biomaterials.

  17. High-Order Thermal Radiative Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Woods, Douglas Nelson [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cleveland, Mathew Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wollaeger, Ryan Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Warsa, James S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-18

    The objective of this research is to asses the sensitivity of the linearized thermal radiation transport equations to finite element order on unstructured meshes and to investigate the sensitivity of the nonlinear TRT equations due to evaluating the opacities and heat capacity at nodal temperatures in 2-D using high-order finite elements.

  18. A Three-Dimensional Nanoporous Silicon Anode for High-Energy Density Lithium-ion Batteries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase I program is directed toward the development of novel, nanoporous silica anodes for low-earth-orbiting (LEO) spacecraft power applications. Silica...

  19. Integration of solid-state nanopores in a 0.5 μm CMOS foundry process.

    Science.gov (United States)

    Uddin, A; Yemenicioglu, S; Chen, C-H; Corigliano, E; Milaninia, K; Theogarajan, L

    2013-04-19

    High-bandwidth and low-noise nanopore sensor and detection electronics are crucial in achieving single-DNA-base resolution. A potential way to accomplish this goal is to integrate solid-state nanopores within a CMOS platform, in close proximity to the biasing electrodes and custom-designed amplifier electronics. Here we report the integration of solid-state nanopore devices in a commercial complementary metal-oxide-semiconductor (CMOS) potentiostat chip implemented in On-Semiconductor's 0.5 μm technology. Nanopore membranes incorporating electrodes are fabricated by post-CMOS micromachining utilizing the n+ polysilicon/SiO2/n+ polysilicon capacitor structure available in the aforementioned process. Nanopores are created in the CMOS process by drilling in a transmission electron microscope and shrinking by atomic layer deposition. We also describe a batch fabrication method to process a large of number of electrode-embedded nanopores with sub-10 nm diameter across CMOS-compatible wafers by electron beam lithography and atomic layer deposition. The CMOS-compatibility of our fabrication process is verified by testing the electrical functionality of on-chip circuitry. We observe high current leakage with the CMOS nanopore devices due to the ionic diffusion through the SiO2 membrane. To prevent this leakage, we coat the membrane with Al2O3, which acts as an efficient diffusion barrier against alkali ions. The resulting nanopore devices also exhibit higher robustness and lower 1/f noise as compared to SiO2 and SiNx. Furthermore, we propose a theoretical model for our low-capacitance CMOS nanopore devices, showing good agreement with the experimental value. In addition, experiments and theoretical models of translocation studies are presented using 48.5 kbp λ-DNA in order to prove the functionality of on-chip pores coated with Al2O3.

  20. Theoretical study on high order interior tomography

    Science.gov (United States)

    Yang, Jiansheng; Cong, Wenxiang; Jiang, Ming; Wang, Ge

    2013-01-01

    In this paper, we study a new type of high order interior problems characterized by high order differential phase shift measurement. This problem is encountered in local x-ray phase-contrast tomography. Here we extend our previous theoretical framework from interior CT to interior differential phase-contrast tomography, and establish the solution uniqueness in this context. We employ the analytic continuation method and high order total variation minimization which we developed in our previous work for interior CT, and prove that an image in a region of interest (ROI) can be uniquely reconstructed from truncated high order differential projection data if the image is known a priori in a sub-region of the ROI or the image is piecewise polynomial in the ROI. Preliminary numerical experiments support the theoretical finding. PMID:23324783

  1. STEM-EELS analysis reveals stable high-density He in nanopores of amorphous silicon coatings deposited by magnetron sputtering.

    Science.gov (United States)

    Schierholz, Roland; Lacroix, Bertrand; Godinho, Vanda; Caballero-Hernández, Jaime; Duchamp, Martial; Fernández, Asunción

    2015-02-20

    A broad interest has been showed recently on the study of nanostructuring of thin films and surfaces obtained by low-energy He plasma treatments and He incorporation via magnetron sputtering. In this paper spatially resolved electron energy-loss spectroscopy in a scanning transmission electron microscope is used to locate and characterize the He state in nanoporous amorphous silicon coatings deposited by magnetron sputtering. A dedicated MATLAB program was developed to quantify the helium density inside individual pores based on the energy position shift or peak intensity of the He K-edge. A good agreement was observed between the high density (∼35-60 at nm(-3)) and pressure (0.3-1.0 GPa) values obtained in nanoscale analysis and the values derived from macroscopic measurements (the composition obtained by proton backscattering spectroscopy coupled to the macroscopic porosity estimated from ellipsometry). This work provides new insights into these novel porous coatings, providing evidence of high-density He located inside the pores and validating the methodology applied here to characterize the formation of pores filled with the helium process gas during deposition. A similar stabilization of condensed He bubbles has been previously demonstrated by high-energy He ion implantation in metals and is newly demonstrated here using a widely employed methodology, magnetron sputtering, for achieving coatings with a high density of homogeneously distributed pores and He storage capacities as high as 21 at%.

  2. Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Kumaresa P S; Dhawale, Dattatray S; Ariga, Katsuhiko; Vinu, Ajayan [International Center for Materials Nanoarchitectonics (MANA), World Premier International (WPI) Research Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Sivakumar, Thiripuranthagan [Department of Chemical Engineering, Anna University, Gundy, Chennai 600025 (India); Aldeyab, Salem S [Department of Chemistry, Petrochemicals Research Chair, Faculty of Science, King Saud University, PO Box 2455 Riyadh 11451 (Saudi Arabia); Zaidi, Javaid S M, E-mail: vinu.ajayan@nims.go.jp [Department of Chemical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2011-08-15

    We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g{sup -1} at a 20 mV s{sup -1} scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

  3. Thermal Transport in Nanoporous Materials for Energy Applications

    Science.gov (United States)

    Fang, Jin

    The present study investigates the complex relationship between nanostructures and microscale thermal transport in nanoporous thin films for energy applications. It experimentally and numerically demonstrates that the effective thermal conductivity of nanoporous materials can be tuned by controlling their nanoscale architectures including porosity, pore diameter, wall thickness, nanocrystal size, and crystallinity as well as surface passivation. This study reports measurements of the cross-plane thermal conductivity of nanoporous thin films with various architectures between 25 and 315 K. Physics-based models combining phonon transport theory and effective medium approximations were developed to interpret the experimental data. Ordered mesoporous titania and silicon thin films were prepared based on evaporation-induced self-assembly method. Pure silica zeolite films were produced by either in-situ growth or by spin coating a zeolite nanoparticle suspension followed by crystal growth upon heating. These synthesized thin films were systematically and fully characterized. They featured ordered nanopores with porosity, pore diameter, and film thickness ranging from 30% to 59%, 0.5 to 25 nm, and 120 to 370 nm, respectively. Their dense matrix was amorphous, polycrystalline, or consisted of an aggregate of nanocrystals. The thermal conductivity of all synthesized nanoporous films increased monotonically with temperature within the temperature range considered. At low temperatures, the nanoporous films behaved like amorphous or strongly disordered materials and their thermal conductivity was proportional to Tn with n varied between 1 and 2.3. At high temperatures, the thermal conductivity increased slowly with temperature or reached a plateau due to strong phonon Umklapp scattering and the saturation of phonon modes. The presence of pores in amorphous mesoporous thin films had a purely geometrical effect by reducing the cross-sectional area through which heat can diffuse

  4. A Dendrite-Free Lithium Metal Battery Model Based on Nanoporous Polymer/Ceramic Composite Electrolytes and High-Energy Electrodes.

    Science.gov (United States)

    Tu, Zhengyuan; Lu, Yingying; Archer, Lynden

    2015-06-10

    Nanoporous polymer/ceramic composite electrolytes that suppress dendrite growth in full-cell, high-energy secondary lithium metal batteries are reported. The battery cathode design used in the study is energetically balanced with the metallic lithium anode. The results reported show that such batteries can stably operate for over 1000 h without signs of short circuit. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. How effective is graphene nanopore geometry on DNA sequencing?

    CERN Document Server

    Satarifard, Vahid; Ejtehadi, Mohammad Reza

    2015-01-01

    In this paper we investigate the effects of graphene nanopore geometry on homopolymer ssDNA pulling process through nanopore using steered molecular dynamic (SMD) simulations. Different graphene nanopores are examined including axially symmetric and asymmetric monolayer graphene nanopores as well as five layer graphene polyhedral crystals (GPC). The pulling force profile, moving fashion of ssDNA, work done in irreversible DNA pulling and orientations of DNA bases near the nanopore are assessed. Simulation results demonstrate the strong effect of the pore shape as well as geometrical symmetry on free energy barrier, orientations and dynamic of DNA translocation through graphene nanopore. Our study proposes that the symmetric circular geometry of monolayer graphene nanopore with high pulling velocity can be used for DNA sequencing.

  6. Preparation of electrochemically active silicon nanotubes in highly ordered arrays

    Directory of Open Access Journals (Sweden)

    Tobias Grünzel

    2013-10-01

    Full Text Available Silicon as the negative electrode material of lithium ion batteries has a very large capacity, the exploitation of which is impeded by the volume changes taking place upon electrochemical cycling. A Si electrode displaying a controlled porosity could circumvent the difficulty. In this perspective, we present a preparative method that yields ordered arrays of electrochemically competent silicon nanotubes. The method is based on the atomic layer deposition of silicon dioxide onto the pore walls of an anodic alumina template, followed by a thermal reduction with lithium vapor. This thermal reduction is quantitative, homogeneous over macroscopic samples, and it yields amorphous silicon and lithium oxide, at the exclusion of any lithium silicides. The reaction is characterized by spectroscopic ellipsometry for thin silica films, and by nuclear magnetic resonance and X-ray photoelectron spectroscopy for nanoporous samples. After removal of the lithium oxide byproduct, the silicon nanotubes can be contacted electrically. In a lithium ion electrolyte, they then display the electrochemical waves also observed for other bulk or nanostructured silicon systems. The method established here paves the way for systematic investigations of how the electrochemical properties (capacity, charge/discharge rates, cyclability of nanoporous silicon negative lithium ion battery electrode materials depend on the geometry.

  7. Preparation of Nano-Porous Activated Carbon Aerogel Using a Single-Step Activation Method for Use as High-Power EDLC Electrode in Organic Electrolyte.

    Science.gov (United States)

    Kwon, Soon Hyung; Kim, Bum-Soo; Kim, Sang-Gil; Lee, Byung-Jun; Kim, Myung-Soo; Jung, Ji Chul

    2016-05-01

    Carbon aerogel was chemically activated with KOH using two different activation methods (conventional activation method and single-step activation method) to yield the nano-porous activated carbon aerogel. Both nano-porous activated carbon aerogels exhibited a better capacitive behavior than carbon aerogel in organic electrolyte. However, a drastic decrease in the specific capacitance with increasing current density was observed in the ACA_C (activated carbon aerogel prepared by a conventional activation method), which is a general tendency of carbon electrode for EDLC in organic electrolyte. Interestingly, the specific capacitance of ACA_S electrode (activated carbon aerogel prepared by a single-step activation method) decreased slowly with increasing current density and its CV curve maintained a rectangular shape well even at a high scan rate of 500 mV/s. The enhanced electrochemical performance of ACA_S at a high current density was attributed to its low ionic resistance caused by the well-developed pore structure with appropriate pore size for easy moving of organic electrolyte ion. Therefore, it can be concluded that single-step activation method could be one of the efficient methods for preparation of nano-porous activated carbon aerogel electrode for high-power EDLC in organic electrolyte.

  8. A novel carbon material with nanopores prepared using a metal-organic framework as precursor for highly selective enrichment of N-linked glycans.

    Science.gov (United States)

    Wang, Yanan; Wang, Jiaxi; Gao, Mingxia; Zhang, Xiangmin

    2017-01-01

    Protein glycosylation plays a key role in many biological processes. In this study, a novel carbon material with nanopores was prepared by carbonization of metal-organic framework (MOF) Mil-101(Cr). The parent MOF assembled from metal ions with bridging organic linkers had many fascinating properties, such as ultrahigh surface area, suitable nanopore structure, and especially a large amount of carbon after being calcined. Due to the strong interactions between carbon and glycans as well as the size-exclusion effect of pore against protein, the N-linked glycans from standard glycoprotein or complex human serum proteins could be identified with high efficiency. The simple synthesis method as well as good enrichment efficiency made this novel carbon material a promising tool for glycosylation research.

  9. High order Poisson Solver for unbounded flows

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Rasmussen, Johannes Tophøj; Chatelain, Philippe

    2015-01-01

    This paper presents a high order method for solving the unbounded Poisson equation on a regular mesh using a Green’s function solution. The high order convergence was achieved by formulating mollified integration kernels, that were derived from a filter regularisation of the solution field....... The method was implemented on a rectangular domain using fast Fourier transforms (FFT) to increase computational efficiency. The Poisson solver was extended to directly solve the derivatives of the solution. This is achieved either by including the differential operator in the integration kernel...... or by performing the differentiation as a multiplication of the Fourier coefficients. In this way, differential operators such as the divergence or curl of the solution field could be solved to the same high order convergence without additional computational effort. The method was applied and validated using...

  10. High-Quality de Novo Genome Assembly of the Dekkera bruxellensis Yeast Using Nanopore MinION Sequencing

    Directory of Open Access Journals (Sweden)

    Téo Fournier

    2017-10-01

    Full Text Available Genetic variation in natural populations represents the raw material for phenotypic diversity. Species-wide characterization of genetic variants is crucial to have a deeper insight into the genotype-phenotype relationship. With the advent of new sequencing strategies and more recently the release of long-read sequencing platforms, it is now possible to explore the genetic diversity of any nonmodel organisms, representing a fundamental resource for biological research. In the frame of population genomic surveys, a first step is to obtain the complete sequence and high-quality assembly of a reference genome. Here, we sequenced and assembled a reference genome of the nonconventional Dekkera bruxellensis yeast. While this species is a major cause of wine spoilage, it paradoxically contributes to the specific flavor profile of some Belgium beers. In addition, an extreme karyotype variability is observed across natural isolates, highlighting that D. bruxellensis genome is very dynamic. The whole genome of the D. bruxellensis UMY321 isolate was sequenced using a combination of Nanopore long-read and Illumina short-read sequencing data. We generated the most complete and contiguous de novo assembly of D. bruxellensis to date and obtained a first glimpse into the genomic variability within this species by comparing the sequences of several isolates. This genome sequence is therefore of high value for population genomic surveys and represents a reference to study genome dynamic in this yeast species.

  11. High-Quality de Novo Genome Assembly of the Dekkera bruxellensis Yeast Isolate Using Nanopore MinION Sequencing.

    Science.gov (United States)

    Fournier, Téo; Gounot, Jean-Sébastien; Freel, Kelle; Cruaud, Corinne; Lemainque, Arnaud; Aury, Jean-Marc; Wincker, Patrick; Schacherer, Joseph; Friedrich, Anne

    2017-08-09

    Genetic variation in natural populations represents the raw material for phenotypic diversity. Species-wide characterization of genetic variants is crucial to have a deeper insight into the genotype-phenotype relationship. With the advent of new sequencing strategies and more recently the release of long-read sequencing platforms, it is now possible to explore the genetic diversity of any non-model organisms, representing a fundamental resource for biological research. In the frame of population genomic surveys, a first step is to obtain the complete sequence and high quality assembly of a reference genome. Here, we sequenced and assembled a reference genome of the non-conventional Dekkera bruxellensis yeast. While this species is a major cause of wine spoilage, it paradoxically contributes to the specific flavor profile of some Belgium beers. In addition, an extreme karyotype variability is observed across natural isolates, highlighting that D. bruxellensis genome is very dynamic. The whole genome of the D. bruxellensis UMY321 isolate was sequenced using a combination of Nanopore long-read and Illumina short-read sequencing data. We generated the most complete and contiguous de novo assembly of D. bruxellensis to date and obtained a first glimpse into the genomic variability within this species by comparing the sequences of several isolates. This genome sequence is therefore of high value for population genomic surveys and represents a reference to study genome dynamic in this yeast species. Copyright © 2017, G3: Genes, Genomes, Genetics.

  12. High-Quality de Novo Genome Assembly of the Dekkera bruxellensis Yeast Using Nanopore MinION Sequencing.

    Science.gov (United States)

    Fournier, Téo; Gounot, Jean-Sébastien; Freel, Kelle; Cruaud, Corinne; Lemainque, Arnaud; Aury, Jean-Marc; Wincker, Patrick; Schacherer, Joseph; Friedrich, Anne

    2017-10-05

    Genetic variation in natural populations represents the raw material for phenotypic diversity. Species-wide characterization of genetic variants is crucial to have a deeper insight into the genotype-phenotype relationship. With the advent of new sequencing strategies and more recently the release of long-read sequencing platforms, it is now possible to explore the genetic diversity of any nonmodel organisms, representing a fundamental resource for biological research. In the frame of population genomic surveys, a first step is to obtain the complete sequence and high-quality assembly of a reference genome. Here, we sequenced and assembled a reference genome of the nonconventional Dekkera bruxellensis yeast. While this species is a major cause of wine spoilage, it paradoxically contributes to the specific flavor profile of some Belgium beers. In addition, an extreme karyotype variability is observed across natural isolates, highlighting that D. bruxellensis genome is very dynamic. The whole genome of the D. bruxellensis UMY321 isolate was sequenced using a combination of Nanopore long-read and Illumina short-read sequencing data. We generated the most complete and contiguous de novo assembly of D. bruxellensis to date and obtained a first glimpse into the genomic variability within this species by comparing the sequences of several isolates. This genome sequence is therefore of high value for population genomic surveys and represents a reference to study genome dynamic in this yeast species. Copyright © 2017 Fournier et al.

  13. Sequence-Specific Covalent Capture Coupled with High-Contrast Nanopore Detection of a Disease-Derived Nucleic Acid Sequence.

    Science.gov (United States)

    Nejad, Maryam Imani; Shi, Ruicheng; Zhang, Xinyue; Gu, Li-Qun; Gates, Kent S

    2017-07-18

    Hybridization-based methods for the detection of nucleic acid sequences are important in research and medicine. Short probes provide sequence specificity, but do not always provide a durable signal. Sequence-specific covalent crosslink formation can anchor probes to target DNA and might also provide an additional layer of target selectivity. Here, we developed a new crosslinking reaction for the covalent capture of specific nucleic acid sequences. This process involved reaction of an abasic (Ap) site in a probe strand with an adenine residue in the target strand and was used for the detection of a disease-relevant T→A mutation at position 1799 of the human BRAF kinase gene sequence. Ap-containing probes were easily prepared and displayed excellent specificity for the mutant sequence under isothermal assay conditions. It was further shown that nanopore technology provides a high contrast-in essence, digital-signal that enables sensitive, single-molecule sensing of the cross-linked duplexes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. High-Order Adaptive Galerkin Methods

    NARCIS (Netherlands)

    Canuto, C.; Nochetto, R.H.; Stevenson, R.; Verani, M.; Kirby, R.M.; Berzins, M.; Hesthaven, J.S.

    2015-01-01

    We design adaptive high-order Galerkin methods for the solution of linear elliptic problems and study their performance. We first consider adaptive Fourier-Galerkin methods and Legendre-Galerkin methods, which offer unlimited approximation power only restricted by solution and data regularity. Their

  15. High-surface-area nanoporous boron carbon nitrides for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Portehault, David; Giordano, Cristina; Antonietti, Markus [Max-Planck-Institute of Colloids and Interfaces, Department of Colloid Chemistry Research, Potsdam (Germany); Gervais, Christel; Sanchez, Clement [UPMC Univ Paris 06, CNRS, UMR 7574 Chimie de la Matiere Condensee de Paris, College de France, Paris (France); Senkovska, Irena; Kaskel, Stefan [Department of Inorganic Chemistry, University of Technology, Dresden (Germany)

    2010-06-09

    Nano- and mesoporous boron carbon nitrides with very high surface areas up to 1560 m{sup 2} g{sup -1} are obtained by pyrolysis of a graphitic carbon nitride mpg-C{sub 3}N{sub 4} infiltrated with a borane complex. This reactive hard-templating approach provides easy composition and texture tuning by temperature adjustment between 800 and 1400 C. The process yields B{sub x}C{sub y}N{sub z}O{sub v}H{sub w} materials as direct copies of the initial template with controlled compositions of 0.15{<=}x{<=}0.36, 0.10{<=}y{<=}0.12, 0.14{<=}z{<=}0.32, and 0.11{<=}v{<=}0.28. The nano and mesoporosities can also be tuned in order to provide hierarchical materials with specific surface areas ranging from 610 to 1560 m{sup 2} g{sup -1}. Such high values, coupled with resistance against air oxidation up to 700 C, suggest potential materials for gas storage and as catalyst supports. Indeed, it is demonstrated that these compounds exhibit high and tunable H{sub 2} uptakes from 0.55 to 1.07 wt.% at 77 K and 1 bar, thus guiding further search of materials for hydrogen storage. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. On nanopore DNA sequencing by signal and noise analysis of ionic current.

    Science.gov (United States)

    Wen, Chenyu; Zeng, Shuangshuang; Zhang, Zhen; Hjort, Klas; Scheicher, Ralph; Zhang, Shi-Li

    2016-05-27

    DNA sequencing, i.e., the process of determining the succession of nucleotides on a DNA strand, has become a standard aid in biomedical research and is expected to revolutionize medicine. With the capability of handling single DNA molecules, nanopore technology holds high promises to become speedier in sequencing at lower cost than what are achievable with the commercially available optics- or semiconductor-based massively parallelized technologies. Despite tremendous progress made with biological and solid-state nanopores, high error rates and large uncertainties persist with the sequencing results. Here, we employ a nano-disk model to quantitatively analyze the sequencing process by examining the variations of ionic current when a DNA strand translocates a nanopore. Our focus is placed on signal-boosting and noise-suppressing strategies in order to attain the single-nucleotide resolution. Apart from decreasing pore diameter and thickness, it is crucial to also reduce the translocation speed and facilitate a stepwise translocation. Our best-case scenario analysis points to severe challenges with employing plain nanopore technology, i.e., without recourse to any signal amplification strategy, in achieving sequencing with the desired single-nucleotide resolution. A conceptual approach based on strand synthesis in the nanopore of the translocating DNA from single-stranded to double-stranded is shown to yield a 10-fold signal amplification. Although it involves no advanced physics and is very simple in mathematics, this simple model captures the essence of nanopore sequencing and is useful in guiding the design and operation of nanopore sequencing.

  17. High performance SERS on nanoporous gold substrates synthesized by chemical de-alloying a Au-based metallic glass

    Science.gov (United States)

    Xue, Yanpeng; Scaglione, Federico; Rizzi, Paola; Battezzati, Livio

    2017-12-01

    A Au20Cu48Ag7Pd5Si20 metallic glass precursor has been used to synthesize nanoporous gold by chemical de-alloying in a mixture of HNO3 and HF. Gold ligaments of size ranging from 45 to 100 nm were obtained as a function of HNO3 concentration, electrolyte temperature and de-alloying time. The as-prepared nanoporous gold exhibited strong surface enhanced Raman scattering (SERS) effect using 4,4‧-bi-pyridine as probe molecule. For application in melamine sensing, the detection limit of 10-6 M was achieved, which indicated that this biocompatible material has great potential as SERS active substrate.

  18. In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

    Science.gov (United States)

    Li, Jin; Fan, C.; Ding, J.; Xue, S.; Chen, Y.; Li, Q.; Wang, H.; Zhang, X.

    2017-01-01

    High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. Here we show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studies show dose-rate-dependent diffusivity of defect clusters. This study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications.

  19. Nanoporous niobium nitride (Nb2N) with enhanced electrocatalytic performance for hydrogen evolution

    Science.gov (United States)

    Li, Yan; Zhang, Jianli; Qian, Xingyue; Zhang, Yue; Wang, Yining; Hu, Rudan; Yao, Chao; Zhu, Junwu

    2018-01-01

    The transition metal nitrides (TMNs) with nanoporous structure have shown great promise as potential electrocatalysts for the hydrogen evolution reaction (HER). Herein, self-organized nanoporous Nb2N was first successfully synthesized through the anodization of niobium in mixed oxalic acid/HF electrolyte, followed by a simple annealing treatment in the ammonia atmosphere. Due to the highly ordered nanoporous structure with abundant active sites and the enhanced electrical conductivity, the Nb2N exhibits a high catalytic current (326.3 mA cm-2) and low onset potential (96.3 mV), which is almost 3.9 times and 4.2 times better than that of Nb2O5, respectively. Meanwhile, the Nb2N also presents low Tafel slope (92 mV dec-1), and excellent cycling durability. More importantly, this study will provide more opportunities for designing and fabricating niobium compounds as an innovative HER catalysts.

  20. Aptamer-functionalized nanoporous gold film for high-performance direct electrochemical detection of bisphenol A in human serum

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ye, E-mail: zhuye@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Zhou, Chuqing; Yan, Xupeng; Yan, Yan [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Wang, Qiang, E-mail: qiangwang@tjut.edu.cn [Institute of New Energy Materials & Low-Carbon Technologies, Tianjin University of Technology, Tianjin 300384 (China)

    2015-07-09

    Highlights: • NPGF exhibits excellent catalytic activity towards the redox reaction of BPA. • The perfect combination of NPGF with aptamer ensures high sensitivity and selectivity. • The detection limit is determined to be 0.056 ± 0.004 nM BPA. • The detection limit is 15-fold lower than gold nanoparticle-based sensor. • The sensor was successfully applied to detect BPA in human serum samples. - Abstract: In the present work, a highly sensitive and selective biosensor based on aptamer-functionalized nanoporous gold film (NPGF) was successfully developed for direct electrochemical detection of bisphenol A (BPA). NPGF was prepared by dealloying Ag from Au/Ag alloy leaf in concentrated nitric acid. The obtained NPGF was attached onto glassy carbon electrode and then was functionalized with BPA-specific aptamer via the formation of Au−S bond. The fabrication of the sensor was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. NPGF exhibited excellent electrocatalytic activity towards the redox reaction of BPA, which ensured high sensitivity of the sensor. The aptamer-captured BPA showed a pair of redox peaks around 0.35/0.28 V (vs. Ag/AgCl). The experimental parameters in terms of aptamer concentration, reaction time, pH, and temperature were optimized. The calibration plot showed a linear range from 0.1 nM to 100 nM BPA with a remarkable detection limit of 0.056 ± 0.004 nM BPA. Particularly, the successful application of the developed sensor for the detection of BPA in human serum samples suggests its promising potential for clinical diagnosis.

  1. High order path integrals made easy.

    Science.gov (United States)

    Kapil, Venkat; Behler, Jörg; Ceriotti, Michele

    2016-12-21

    The precise description of quantum nuclear fluctuations in atomistic modelling is possible by employing path integral techniques, which involve a considerable computational overhead due to the need of simulating multiple replicas of the system. Many approaches have been suggested to reduce the required number of replicas. Among these, high-order factorizations of the Boltzmann operator are particularly attractive for high-precision and low-temperature scenarios. Unfortunately, to date, several technical challenges have prevented a widespread use of these approaches to study the nuclear quantum effects in condensed-phase systems. Here we introduce an inexpensive molecular dynamics scheme that overcomes these limitations, thus making it possible to exploit the improved convergence of high-order path integrals without having to sacrifice the stability, convenience, and flexibility of conventional second-order techniques. The capabilities of the method are demonstrated by simulations of liquid water and ice, as described by a neural-network potential fitted to the dispersion-corrected hybrid density functional theory calculations.

  2. High order path integrals made easy

    Science.gov (United States)

    Kapil, Venkat; Behler, Jörg; Ceriotti, Michele

    2016-12-01

    The precise description of quantum nuclear fluctuations in atomistic modelling is possible by employing path integral techniques, which involve a considerable computational overhead due to the need of simulating multiple replicas of the system. Many approaches have been suggested to reduce the required number of replicas. Among these, high-order factorizations of the Boltzmann operator are particularly attractive for high-precision and low-temperature scenarios. Unfortunately, to date, several technical challenges have prevented a widespread use of these approaches to study the nuclear quantum effects in condensed-phase systems. Here we introduce an inexpensive molecular dynamics scheme that overcomes these limitations, thus making it possible to exploit the improved convergence of high-order path integrals without having to sacrifice the stability, convenience, and flexibility of conventional second-order techniques. The capabilities of the method are demonstrated by simulations of liquid water and ice, as described by a neural-network potential fitted to the dispersion-corrected hybrid density functional theory calculations.

  3. High-order nonuniformly correlated beams

    Science.gov (United States)

    Wu, Dan; Wang, Fei; Cai, Yangjian

    2018-02-01

    We have introduced a class of partially coherent beams with spatially varying correlations named high-order nonuniformly correlated (HNUC) beams, as an extension of conventional nonuniformly correlated (NUC) beams. Such beams bring a new parameter (mode order) which is used to tailor the spatial coherence properties. The behavior of the spectral density of the HNUC beams on propagation has been investigated through numerical examples with the help of discrete model decomposition and fast Fourier transform (FFT) algorithm. Our results reveal that by selecting the mode order appropriately, the more sharpened intensity maxima can be achieved at a certain propagation distance compared to that of the NUC beams, and the lateral shift of the intensity maxima on propagation is closed related to the mode order. Furthermore, analytical expressions for the r.m.s width and the propagation factor of the HNUC beams on free-space propagation are derived by means of Wigner distribution function. The influence of initial beam parameters on the evolution of the r.m.s width and the propagation factor, and the relation between the r.m.s width and the occurring of the sharpened intensity maxima on propagation have been studied and discussed in detail.

  4. Tunable Intense High-Order Vortex Generation.

    Science.gov (United States)

    Zhang, Xiaomei; Shen, Baifei

    2017-10-01

    In 2015, we found the scheme to generate intense high-order optical vortices that carry OAM in the extreme ultraviolet region based on relativistic harmonics from the surface of a solid target. The topological charge of the harmonics scales with its order. These results have been confirmed in recent experiments. In the two incident beams case, we produced relativistic intense harmonics with expected frequency and optical vortex. When two counter-propagating LG laser pulses impinge on a solid thin foil and interact with each other, the contribution of each input pulse in producing harmonics can be distinguished with the help of angular momentum conservation of photons, which is almost impossible for harmonic generation without optical vortex. The generation of tunable, intense vortex harmonics with different photon topological charge is predicted based on the theoretical analysis and 3D PIC simulations. This work was supported by the National Natural Science Foundation of China (Grant Nos. 11374319, 11674339).

  5. Advanced nanoporous materials for micro-gravimetric sensing to trace-level bio/chemical molecules.

    Science.gov (United States)

    Xu, Pengcheng; Li, Xinxin; Yu, Haitao; Xu, Tiegang

    2014-10-13

    Functionalized nanoporous materials have been developed recently as bio/chemical sensing materials. Due to the huge specific surface of the nano-materials for molecular adsorption, high hopes have been placed on gravimetric detection with micro/nano resonant cantilevers for ultra-sensitive sensing of low-concentration bio/chemical substances. In order to enhance selectivity of the gravimetric resonant sensors to the target molecules, it is crucial to modify specific groups onto the pore-surface of the nano-materials. By loading the nanoporous sensing material onto the desired region of the mass-type transducers like resonant cantilevers, the micro-gravimetric bio/chemical sensors can be formed. Recently, such micro-gravimetric bio/chemical sensors have been successfully applied for rapid or on-the-spot detection of various bio/chemical molecules at the trace-concentration level. The applicable nanoporous sensing materials include mesoporous silica, zeolite, nanoporous graphene oxide (GO) and so on. This review article focuses on the recent achievements in design, preparation, functionalization and characterization of advanced nanoporous sensing materials for micro-gravimetric bio/chemical sensing.

  6. High-temperature ordered intermetallic alloys V

    Energy Technology Data Exchange (ETDEWEB)

    Baker, I. (ed.) (Dartmouth Coll., Hanover, NH (United States). Thayer School of Engineering); Darolia, R. (ed.) (GE Aircraft Engines, Cincinnati, OH (United States)); Whittenberger, J.D. (ed.) (NASA, Cleveland, OH (United States). Lewis Research Center); Yoo, M.H. (ed.) (Oak Ridge National Lab., TN (United States))

    1993-01-01

    These proceedings represent the written record of the High-Temperature Ordered Intermetallic Alloys 5 Symposium which was held in conjunction with the 1992 Fall Materials Research Society meeting in Boston, Massachusetts. This symposium, which was the fifth in the series originated by C.C Koch, C.T. Liu and N.S. Stoloff in 1984, was very successful with 86 oral presentations over four days, and approximately 140 posters given during two lively evening sessions. Such a response, in view of the increasing number of conferences being held on intermetallics each year, reveals the continued high regard for this series of symposia. Individual papers have been processed separately for inclusion in the appropriate data bases.

  7. An electron paramagnetic resonance spectroscopy investigation of the retention mechanisms of Mn and Cu in the nanopore channels of three zeolite minerals

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Daniel R.; Schulthess, Cristian P.; Amonette, James E.; Walter, Eric D.

    2012-12-01

    The adsorption mechanisms of divalent cations in zeolite nanopore channels can vary as a function of their pore dimensions. The nanopore inner-sphere enhancement (NISE) theory predicts that ions may dehydrate inside small nanopore channels in order to adsorb more closely to the mineral surface if the nanopore channel is sufficiently small. The results of an electron paramagnetic resonance (EPR) spectroscopy study of Mn and Cu adsorption on the zeolite minerals zeolite Y (large nanopores), ZSM-5 (intermediate nanopores), and mordenite (small nanopores) are presented. The Cu and Mn cations both adsorbed via an outer-sphere mechanism on zeolite Y based on the similarity between the adsorbed spectra and the aqueous spectra. Conversely, Mn and Cu adsorbed via an inner-sphere mechanism on mordenite based on spectrum asymmetry and peak broadening of the adsorbed spectra. However, Mn adsorbed via an outer-sphere mechanism on ZSM-5, whereas Cu adsorbed on ZSM-5 shows a high degree of surface interaction that indicates that it is adsorbed closer to the mineral surface. Evidence of dehydration and immobility was more readily evident in the spectrum of mordenite than ZSM-5, indicating that Cu was not as close to the surface on ZSM-5 as it was when adsorbed on mordenite. Divalent Mn cations are strongly hydrated and are held strongly only in zeolites with small nanopore channels. Divalent Cu cations are also strongly hydrated, but can dehydrate more easily, presumably due to the Jahn-Teller effect, and are held strongly in zeolites with medium sized nanopore channels or smaller.

  8. Nanoporous Delafossite CuAlO 2 from Inorganic/Polymer Double Gels: A Desirable High-Surface-Area p-Type Transparent Electrode Material

    Energy Technology Data Exchange (ETDEWEB)

    Das, Barun; Renaud, Adèle; Volosin, Alex M.; Yu, Lei; Newman, Nathan; Seo, Dong-Kyun

    2015-02-02

    Nanoporous structures of a p-type semiconductor, delafossite CuAlO2, with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott–Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO2 are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott–Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO2 exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.

  9. Nanoporous Delafossite CuAlO 2 from Inorganic/Polymer Double Gels: A Desirable High-Surface-Area p-Type Transparent Electrode Material

    Energy Technology Data Exchange (ETDEWEB)

    Das, Barun; Renaud, Adèle; Volosin, Alex M.; Yu, Lei; Newman, Nathan; Seo, Dong-Kyun

    2015-02-02

    Nanoporous structures of a p-type semiconductor, delafossite CuAlO2, with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott–Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO2 are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott–Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO2 exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.

  10. Nanoporous delafossite CuAlO2 from inorganic/polymer double gels: a desirable high-surface-area p-type transparent electrode material.

    Science.gov (United States)

    Das, Barun; Renaud, Adèle; Volosin, Alex M; Yu, Lei; Newman, Nathan; Seo, Dong-Kyun

    2015-02-02

    Nanoporous structures of a p-type semiconductor, delafossite CuAlO(2), with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott-Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO(2) are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott-Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO(2) exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.

  11. Facile synthesis of graphitic C3N4 nanoporous-tube with high enhancement of visible-light photocatalytic activity

    Science.gov (United States)

    Zhao, Ruiru; Gao, Jianping; Mei, Shunkang; Wu, Yongli; Wang, Xiaoxue; Zhai, Xiangang; Yang, Jiangbing; Hao, Chaoyue; Yan, Jing

    2017-12-01

    A simple and convenient method was used to synthesize a graphitic carbon nitride (g-C3N4) nanoporous-tube by using SiO2 nanoparticles as pore formers. The structure of the g-C3N4 nanoporous-tube was characterized by the SEM and TEM images. Taking photodegradation of RhB as an example, the photocatalytic activity of the as-prepared g-C3N4 nanoporous-tube was investigated. It can photodegrade 90% RhB in 40 min under visible-light irradiation and obtain a k value of 0.04491 min‑1, which is 8.16 times that of bulk g-C3N4, 3.09 times that of tubular g-C3N4 and 1.48 times that of tubular g-C3N4-SiO2. The significant enhancement in photocatalytic efficiency is due to the edge effect of the pores and the special structure of the tubes. In addition, the possible mechanism of photocatalytic degradation of RhB was also proposed based on the trapping experiment of active species, which indicated that the superoxide radicals ({{{{O}}}2}\\bullet -) and the holes (h +) were the main reactive species in this photocatalyst. This work may open up a new idea of innovation in g-C3N4 structure and inspire its follow-up study.

  12. High electrokinetic energy conversion efficiency in charged nanoporous nitrocellulose/sulfonated polystyrene membranes.

    Science.gov (United States)

    Haldrup, Sofie; Catalano, Jacopo; Hansen, Michael Ryan; Wagner, Manfred; Jensen, Grethe Vestergaard; Pedersen, Jan Skov; Bentien, Anders

    2015-02-11

    The synthesis, characterization, and electrokinetic energy conversion performance have been investigated experimentally in a charged polymeric membrane based on a blend of nitrocellulose and sulfonated polystyrene. The membrane is characterized by a moderate ion exchange capacity and a relatively porous structure with average pore diameter of 11 nm. With electrokinetic energy conversion, pressure can be converted directly into electric energy and vice versa. From the electrokinetic transport properties, a remarkably large intrinsic maximum efficiency of 46% is found. It is anticipated that the results are an experimental verification of theoretical models that predict high electrokinetic energy conversion efficiency in pores with high permselectivity and hydrodynamic slip flow. Furthermore, the result is a promising step for obtaining efficient low-cost electrokinetic generators and pumps for small or microscale applications.

  13. TRANSFORMATIONS IN NANO-DIAMONDS WITH FORMATION OF NANO-POROUS SILICON CARBIDE AT HIGH PRESSURE

    Directory of Open Access Journals (Sweden)

    V. N. Kovalevsky

    2010-01-01

    Full Text Available The paper contains investigations on regularities of diamond - silicon carbide composite structure formation at impact-wave excitation. It has been determined that while squeezing a porous blank containing Si (SiC nano-diamond by explosive detonation products some processes are taking place such as diamond nano-particles consolidation, reverse diamond transition into graphite, fragments formation from silicon carbide. A method for obtaining high-porous composites with the presence of ultra-disperse diamond particles has been developed. Material with three-dimensional high-porous silicon-carbide structure has been received due to nano-diamond graphitation at impact wave transmission and plastic deformation. The paper reveals nano-diamonds inverse transformation into graphite and its subsequent interaction with the silicon accompanied by formation of silicon-carbide fragments with dimensions of up to 100 nm.

  14. Controllable fabrication of highly ordered thin AAO template on Si substrate for electrodeposition of nanostructures

    Science.gov (United States)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Qaeed, M. A.

    2014-09-01

    In this work, simple fabrication of hexagonally highly ordered porous anodic aluminum oxide (AAO) of Al thin film (1 μm) on Si substrate is described using two-step anodization method for electrochemical synthesis of nanostructures. In this method, the templates were prepared under the controllable conditions of the parameters, which give rise to the possibility of highly ordered nanopore arrays with a well aspect ratio. Pore widening was then fulfilled in 5 wt% phosphoric acid solution at 25 °C. The pore diameter and spacing are proportional to the applied voltage, which is due to the mechanical stress associated with the volume expansion of the aluminum during the anodization according to the mechanical stress model. Pore-widening solution adjusted the pore diameter and thinned the AAO barrier layer at room temperature under the control of etching time. As an application, Cu nanorods arrays embedded in anodic alumina (AAO) template were fabricated by dc electrodeposition. The characterization of the AAO templates and the Cu nanorods produced was made by X-ray diffraction, field emission scanning microscope, energy dispersive X-ray spectroscopy and atomic force microscope (AFM). The images of AFM show that porous AAO template under constant voltage is 40 V which presents the optimum ordering.

  15. Magnetic solid-phase extraction using nanoporous three dimensional graphene hybrid materials for high-capacity enrichment and simultaneous detection of nine bisphenol analogs from water sample.

    Science.gov (United States)

    Wang, Lingling; Zhang, Zhenzhen; Zhang, Jing; Zhang, Lei

    2016-09-09

    The synthesis of a magnetic nanoporous three dimensional graphene (3DG)/ZnFe2O4 composite has been achieved. Through formation of graphene hydrogel, ZnFe2O4 magnetic particles was successfully introduced into the nanoporous 3DG, resulting in a magnetic porous carbon material. The morphology, structure, and magnetic behavior of the as-prepared 3DG/ZnFe2O4 were characterized by using the techniques of SEM, XRD, BET, VSM, FTIR, Raman and TGA. The 3DG/ZnFe2O4 has a high specific surface area and super paramagnetism. Its performance was evaluated by the magnetic solid-phase extraction of nine bisphenol analogs (BPs) from water samples followed by HPLC analysis, and showed excellent adsorption capability for the nine target compounds. Under optimized condition, the lower method detection limits (0.05-0.18ngmL(-1)), the higher enrichment factors (800 fold) and good recoveries (95.1-103.8%) with relative standard deviation (RSD) values less than 6.2% were achieved. The results indicated that the developed method based on the use of 3DG/ZnFe2O4 as the magnetic adsorbent has the advantages of convenience and high efficiency, and can be successfully applied to detect the nine BPs in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Nanoporous Silicified Phospholipids and Application to Controlled Glycolic Acid Release

    Directory of Open Access Journals (Sweden)

    Kang SangHwa

    2008-01-01

    Full Text Available Abstract This work demonstrates the synthesis and characterization of novel nanoporous silicified phospholipid bilayers assembled inorganic powders. The materials are obtained by silicification process with silica precursor at the hydrophilic region of phospholipid bilayers. This process involves the co-assembly of a chemically active phospholipids bilayer within the ordered porosity of a silica matrix and holds promise as a novel application for controlled drug release or drug containers with a high level of specificity and throughput. The controlled release application of the synthesized materials was achieved to glycolic acid, and obtained a zero-order release pattern due to the nanoporosity.

  17. Nanoporous polymer electrolyte

    Science.gov (United States)

    Elliott, Brian [Wheat Ridge, CO; Nguyen, Vinh [Wheat Ridge, CO

    2012-04-24

    A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

  18. High order Bragg grating microfluidic dye laser

    DEFF Research Database (Denmark)

    Balslev, Søren; Kristensen, Anders

    2004-01-01

    We demonstrate a single mode distributed feedback liquid dye laser, based on a short 133 'rd order Bragg grating defined in a single polymer layer between two glass substrates.......We demonstrate a single mode distributed feedback liquid dye laser, based on a short 133 'rd order Bragg grating defined in a single polymer layer between two glass substrates....

  19. High order stiffly stable linear multistep methods

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, C.N.

    1979-01-01

    Stiffly stable linear k-step methods of order k for the initial-value problem are studied. Examples for k = 1, 2, and 3 were discovered by use of Adams-type methods. A large family of stiffly stable linear 7-step methods of order 7 was also found.

  20. High order harmonic generation in rare gases

    Energy Technology Data Exchange (ETDEWEB)

    Budil, Kimberly Susan [Univ. of California, Davis, CA (United States)

    1994-05-01

    The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I ~1013-1014 W/cm2) is focused into a dense (~1017 particles/cm3) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic "source". A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.

  1. Evaporation-induced self-assembled silica colloidal particle-assisted nanoporous structural evolution of poly(ethylene terephthalate) nonwoven composite separators for high-safety/high-rate lithium-ion batteries

    Science.gov (United States)

    Lee, Jung-Ran; Won, Ji-Hye; Kim, Jong Hun; Kim, Ki Jae; Lee, Sang-Young

    2012-10-01

    A facile approach to the fabrication of nanoporous structure-tuned nonwoven composite separators is demonstrated for application in high-safety/high-rate lithium-ion batteries. This strategy is based on the construction of silica (SiO2) colloidal particle-assisted nanoporous structure in a poly(ethylene terephthalate) (PET) nonwoven substrate. The nanoparticle arrangement arising from evaporation-induced self-assembly of SiO2 colloidal particles allows the evolution of the unusual nanoporous structure, i.e. well-connected interstitial voids formed between close-packed SiO2 particles adhered by styrene-butadiene rubber (SBR) binders. Meanwhile, the PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The aforementioned structural novelty of the nonwoven composite separator plays a key role in providing the separator with advantageous characteristics (specifically, good electrolyte wettability, high ionic conductivity, and benign compatibility with electrodes), which leads to the better cell performance than a commercialized polyethylene (PE) separator.

  2. Deformation Behavior of Nanoporous Metals

    Energy Technology Data Exchange (ETDEWEB)

    Biener, J; Hodge, A M; Hamza, A V

    2007-11-28

    Nanoporous open-cell foams are a rapidly growing class of high-porosity materials (porosity {ge} 70%). The research in this field is driven by the desire to create functional materials with unique physical, chemical and mechanical properties where the material properties emerge from both morphology and the material itself. An example is the development of nanoporous metallic materials for photonic and plasmonic applications which has recently attracted much interest. The general strategy is to take advantage of various size effects to introduce novel properties. These size effects arise from confinement of the material by pores and ligaments, and can range from electromagnetic resonances to length scale effects in plasticity. In this chapter we will focus on the mechanical properties of low density nanoporous metals and how these properties are affected by length scale effects and bonding characteristics. A thorough understanding of the mechanical behavior will open the door to further improve and fine-tune the mechanical properties of these sometimes very delicate materials, and thus will be crucial for integrating nanoporous metals into products. Cellular solids with pore sizes above 1 micron have been the subject of intense research for many years, and various scaling relations describing the mechanical properties have been developed.[4] In general, it has been found that the most important parameter in controlling their mechanical properties is the relative density, that is, the density of the foam divided by that of solid from which the foam is made. Other factors include the mechanical properties of the solid material and the foam morphology such as ligament shape and connectivity. The characteristic internal length scale of the structure as determined by pores and ligaments, on the other hand, usually has only little effect on the mechanical properties. This changes at the submicron length scale where the surface-to-volume ratio becomes large and the effect

  3. A simple template-free synthesis of nanoporous ZnS-In2S3-Ag2S solid solutions for highly efficient photocatalytic H2 evolution under visible light.

    Science.gov (United States)

    Li, Yingxuan; Chen, Gang; Zhou, Chao; Sun, Jingxue

    2009-04-21

    Nanoporous ZnS-In(2)S(3)-Ag(2)S solid solutions synthesized by a facile template-free method showed relatively high activities for photocatalytic H(2) evolution under visible-light irradiation (lambda >400 nm) even in the absence of co-catalysts.

  4. Nanoporous gold synthesized by plasma-assisted inert gas condensation: room temperature sintering, nanoscale mechanical properties and stability against high energy electron irradiation

    Science.gov (United States)

    Weyrauch, S.; Wagner, C.; Suckfuell, C.; Lotnyk, A.; Knolle, W.; Gerlach, J. W.; Mayr, S. G.

    2018-02-01

    With a plasma assisted gas condensation system it is possible to achieve high-purity nanoporous Au (np-Au) structures with minimal contaminations and impurities. The structures consist of single Au-nanoparticles, which partially sintered together due to their high surface to volume ratio. Through electron microscopy investigations a porosity  >50% with ligament sizes between 20–30 nm was revealed. The elastic modulus of the np-Au was determined via peak force quantitative nanomechanical mapping and resulted in values of 7.5  ±  1.5 GPa. The presented structures partially sintered at room temperature, but proved to be stable to electron irradiation with energies of 7 MeV up to doses of 100 MGy. The electron irradiation stability opens the venue for electron assisted functionalization with biomolecules.

  5. Nanopore formation on Au coated pyramid under electron beam irradiations (plasmonic nanopore on pyramid

    Directory of Open Access Journals (Sweden)

    Seong Soo Choi

    2016-03-01

    Full Text Available There have been tremendous interests about the single molecule analysis using a sold-state nanopore. The solid-state nanopore can be fabricated either by drilling technique, or diffusion technique by using electron beam irradiations. The solid-state SiN nanopore device with electrical detection technique recently fabricated, however, the solid-state Au nanopore with optical detection technique can be better utilized as the next generation single molecule sensor. In this report, the nanometer size openings with its size less than 10 nm on the diffused membrane on the 200 nm Au pyramid were fabricated by using field emission scanning electron microscopy (FESEM electron beam irradiations, transmission electron microscopy (TEM, etc. After the sample was being kept under a room environment for several months, several Au (111 clusters with ~6 nm diameter formed via Ostwald ripening are observed using a high resolution TEM imaging. The nanopore with Au nanoclusters on the diffused membrane can be utilized as an optical nanopore device.

  6. Hydrophilic and size-controlled graphene nanopores for protein detection

    Science.gov (United States)

    Goyal, Gaurav; Bok Lee, Yong; Darvish, Armin; Ahn, Chi Won; Kim, Min Jun

    2016-12-01

    This paper describes a general approach for transferring clean single-layer graphene onto silicon nitride nanopore devices and the use of the electron beam of a transmission electron microscope (TEM) to drill size-controlled nanopores in freely suspended graphene. Besides nanopore drilling, we also used the TEM to heal and completely close the unwanted secondary holes formed by electron beam damage during the drilling process. We demonstrate electron beam assisted shrinking of irregularly shaped 40-60 nm pores down to 2 nm, exhibiting an exquisite control of graphene nanopore diameter. Our fabrication workflow also rendered graphene nanopores hydrophilic, allowing easy wetting and use of the pores for studying protein translocation and protein-protein interaction with a high signal to noise ratio.

  7. Entropic cages for trapping DNA near a nanopore

    Science.gov (United States)

    Liu, Xu; Skanata, Mirna Mihovilovic; Stein, Derek

    2015-02-01

    Nanopores can probe the structure of biopolymers in solution; however, diffusion makes it difficult to study the same molecule for extended periods. Here we report devices that entropically trap single DNA molecules in a 6.2-femtolitre cage near a solid-state nanopore. We electrophoretically inject DNA molecules into the cage through the nanopore, pause for preset times and then drive the DNA back out through the nanopore. The saturating recapture time and high recapture probability after long pauses, their agreement with a convection-diffusion model and the observation of trapped DNA under fluorescence microscopy all confirm that the cage stably traps DNA. Meanwhile, the cages have 200 nm openings that make them permeable to small molecules, like the restriction endonuclease we use to sequence-specifically cut trapped DNA into fragments whose number and sizes are analysed upon exiting through the nanopore. Entropic cages thus serve as reactors for chemically modifying single DNA molecules.

  8. High order dark wavefront sensing simulations

    Science.gov (United States)

    Ragazzoni, Roberto; Arcidiacono, Carmelo; Farinato, Jacopo; Viotto, Valentina; Bergomi, Maria; Dima, Marco; Magrin, Demetrio; Marafatto, Luca; Greggio, Davide; Carolo, Elena; Vassallo, Daniele

    2016-07-01

    Dark wavefront sensing takes shape following quantum mechanics concepts in which one is able to "see" an object in one path of a two-arm interferometer using an as low as desired amount of light actually "hitting" the occulting object. A theoretical way to achieve such a goal, but in the realm of wavefront sensing, is represented by a combination of two unequal beams interferometer sharing the same incoming light, and whose difference in path length is continuously adjusted in order to show different signals for different signs of the incoming perturbation. Furthermore, in order to obtain this in white light, the path difference should be properly adjusted vs the wavelength used. While we incidentally describe how this could be achieved in a true optomechanical setup, we focus our attention to the simulation of a hypothetical "perfect" dark wavefront sensor of this kind in which white light compensation is accomplished in a perfect manner and the gain is selectable in a numerical fashion. Although this would represent a sort of idealized dark wavefront sensor that would probably be hard to match in the real glass and metal, it would also give a firm indication of the maximum achievable gain or, in other words, of the prize for achieving such device. Details of how the simulation code works and first numerical results are outlined along with the perspective for an in-depth analysis of the performances and its extension to more realistic situations, including various sources of additional noise.

  9. High-order harmonic generation from eld-distorted orbitals

    DEFF Research Database (Denmark)

    Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer

    We investigate the eect on high-order harmonic generation of the distortion of molecular orbitals by the driving laser eld. Calculations for high-order harmonic generation including orbital distortion are performed for N2 (high polarizability). Our results allow us to suggest that field...... of the minimum in the high-order harmonic spectra. This is in agreement with experiment....

  10. Hydrophilic nanoporous materials

    DEFF Research Database (Denmark)

    2010-01-01

    The present application discloses a method for preparing and rendering hydrophilic a nanoporous material of a polymer matrix which has a porosity of 0.1-90 percent (v/v), such that the ratio between the final water absorption (percent (w/w)) and the porosity (percent (v/v)) is at least 0.05, the ......The present application discloses a method for preparing and rendering hydrophilic a nanoporous material of a polymer matrix which has a porosity of 0.1-90 percent (v/v), such that the ratio between the final water absorption (percent (w/w)) and the porosity (percent (v/v)) is at least 0.......05, the method comprising the steps of: (a) preparing a precursor material comprising at least one polymeric component and having a first phase and a second phase; (b) removal of at least a part of the first phase of the precursor material prepared in step (a) so as to leave behind a nanoporous material...... of the polymer matrix; (c) irradiating at least a part of said nanoporous material with light of a wave length of in the range of 250-400 nm (or 200-700 nm) in the presence of oxygen and/or ozone. Corresponding hydrophilic nanoporous materials are also disclosed. L...

  11. Engineering the internal surfaces of three-dimensional nanoporous catalysts by surfactant-modified dealloying.

    Science.gov (United States)

    Wang, Zhili; Liu, Pan; Han, Jiuhui; Cheng, Chun; Ning, Shoucong; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

    2017-10-20

    Tuning surface structures by bottom-up synthesis has been demonstrated as an effective strategy to improve the catalytic performances of nanoparticle catalysts. Nevertheless, the surface modification of three-dimensional nanoporous metals, fabricated by a top-down dealloying approach, has not been achieved despite great efforts devoted to improving the catalytic performance of three-dimensional nanoporous catalysts. Here we report a surfactant-modified dealloying method to tailor the surface structure of nanoporous gold for amplified electrocatalysis toward methanol oxidation and oxygen reduction reactions. With the assistance of surfactants, {111} or {100} faceted internal surfaces of nanoporous gold can be realized in a controllable manner by optimizing dealloying conditions. The surface modified nanoporous gold exhibits significantly enhanced electrocatalytic activities in comparison with conventional nanoporous gold. This study paves the way to develop high-performance three-dimensional nanoporous catalysts with a tunable surface structure by top-down dealloying for efficient chemical and electrochemical reactions.

  12. DNA strands attached inside single conical nanopores: ionic pore characteristics and insight into DNA biophysics.

    Science.gov (United States)

    Nguyen, Gael; Howorka, Stefan; Siwy, Zuzanna S

    2011-01-01

    Single nanopores attract a great deal of scientific interest as a basis for biosensors and as a system to study the interactions and behavior of molecules in a confined volume. Tuning the geometry and surface chemistry of nanopores helps create devices that control transport of ions and molecules in solution. Here, we present single conically shaped nanopores whose narrow opening of 8 or 12 nm is modified with single-stranded DNA molecules. We find that the DNA occludes the narrow opening of nanopores and that the blockade extent decreases with the ionic strength of the background electrolyte. The results are explained by the ionic strength dependence of the persistence length of DNA. At low KCl concentrations (10 mM) the molecules assume an extended and rigid conformation, thereby blocking the pore lumen and reducing the flow of ionic current to a greater extent than compacted DNA at high salt concentrations. Attaching flexible polymers to the pore walls hence creates a system with tunable opening diameters in order to regulate transport of both neutral and charged species.

  13. Building membrane nanopores

    Science.gov (United States)

    Howorka, Stefan

    2017-07-01

    Membrane nanopores--hollow nanoscale barrels that puncture biological or synthetic membranes--have become powerful tools in chemical- and biosensing, and have achieved notable success in portable DNA sequencing. The pores can be self-assembled from a variety of materials, including proteins, peptides, synthetic organic compounds and, more recently, DNA. But which building material is best for which application, and what is the relationship between pore structure and function? In this Review, I critically compare the characteristics of the different building materials, and explore the influence of the building material on pore structure, dynamics and function. I also discuss the future challenges of developing nanopore technology, and consider what the next-generation of nanopore structures could be and where further practical applications might emerge.

  14. Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

    Science.gov (United States)

    Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

    2012-07-01

    The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm2) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

  15. Gyroid Nanoporous Membranes with Tunable Permeability

    DEFF Research Database (Denmark)

    Li, Li; Schulte, Lars; Clausen, Lydia D.

    2011-01-01

    Understanding the relevant permeability properties of ultrafiltration membranes is facilitated by using materials and procedures that allow a high degree of control on morphology and chemical composition. Here we present the first study on diffusion permeability through gyroid nanoporous cross-linked...

  16. Electrophoresis of a polyelectrolyte through a nanopore

    Science.gov (United States)

    Ghosal, Sandip

    2006-11-01

    Translocation of polyelectrolytes (such as DNA) through natural and artificial nanopores can be detected with single molecule resolution by monitoring the resistivity of the pore (Nature Biotechnology (2001) 19, pp. 248). The technique could evolve into a technology for sequencing DNA at speeds that are orders of magnitude faster than what is currently possible. Here a hydrodynamic model to determine the electrophoretic speed of a polyelectrolyte through a nanopore is presented. It is assumed that the speed is determined by a balance of electrical and viscous forces arising from within the pore and that classical continuum electrostatics and hydrodynamics may be considered applicable. An explicit formula for the translocation speed as a function of the pore geometry and other physical parameters is obtained and is shown to be consistent with experimental measurements on DNA translocation through nanopores in silicon membranes. Secondary effects such as the hydrodynamic friction on the part of the polymer outside the nanopore must also be considered to explain the weak dependence of the translocation speed on the polymer length.

  17. Edge-functionalized nanoporous carbons for high adsorption capacity and selectivity of CO2 over N2

    Science.gov (United States)

    Zhou, Sainan; Guo, Chen; Wu, Zhonghua; Wang, Maohuai; Wang, Zhaojie; Wei, Shuxian; Li, Shaoren; Lu, Xiaoqing

    2017-07-01

    Single-component adsorption and competitive behavior of binary CO2/N2 mixture in the edge-functionalized nanoporous carbons (NPCs) were investigated by grand canonical Monte Carlo simulation. Results demonstrated that edge-functionalization effectively improved the pore topology and morphological characteristics of NPCs. Evaluation of adsorption capacity and analyses of the isosteric heat and radial distribution functions confirmed that edge-functionalization can evidently enhance the single-component adsorption of CO2/N2. Temperature had a negative effect on the single-component adsorption of CO2/N2 whereas pressure had a positive effect before adsorption reaches a stable equilibrium state. Edge-functionalization can significantly increase the selectivity of CO2 over N2 in NPCs, which demonstrate the following sequence according to selectivity: NH2sbnd NPC > COOHsbnd NPC > OHsbnd NPC > Hsbnd NPC > NPC. The increased CO2 molar fraction in the binary CO2/N2 mixture decreased the selectivity and saturation pressure to reach a stable equilibrium state. Overall, this work highlighted the effects of edge-functionalization on the adsorption and separation of CO2/N2 in NPCs, and provided an effective strategy for designing and screening adsorbent materials for carbon capture and separation.

  18. Slow DNA transport through nanopores in hafnium oxide membranes.

    Science.gov (United States)

    Larkin, Joseph; Henley, Robert; Bell, David C; Cohen-Karni, Tzahi; Rosenstein, Jacob K; Wanunu, Meni

    2013-11-26

    We present a study of double- and single-stranded DNA transport through nanopores fabricated in ultrathin (2-7 nm thick) freestanding hafnium oxide (HfO2) membranes. The high chemical stability of ultrathin HfO2 enables long-lived experiments with 50 000 DNA translocations with no detectable pore expansion. Mean DNA velocities are slower than velocities through comparable silicon nitride pores, providing evidence that HfO2 nanopores have favorable physicochemical interactions with nucleic acids that can be leveraged to slow down DNA in a nanopore.

  19. Computational modeling of ion transport through nanopores

    Science.gov (United States)

    Modi, Niraj; Winterhalter, Mathias; Kleinekathöfer, Ulrich

    2012-09-01

    Nanoscale pores are ubiquitous in biological systems while artificial nanopores are being fabricated for an increasing number of applications. Biological pores are responsible for the transport of various ions and substrates between the different compartments of biological systems separated by membranes while artificial pores are aimed at emulating such transport properties. As an experimental method, electrophysiology has proven to be an important nano-analytical tool for the study of substrate transport through nanopores utilizing ion current measurements as a probe for the detection. Independent of the pore type, i.e., biological or synthetic, and objective of the study, i.e., to model cellular processes of ion transport or electrophysiological experiments, it has become increasingly important to understand the dynamics of ions in nanoscale confinements. To this end, numerical simulations have established themselves as an indispensable tool to decipher ion transport processes through biological as well as artificial nanopores. This article provides an overview of different theoretical and computational methods to study ion transport in general and to calculate ion conductance in particular. Potential new improvements in the existing methods and their applications are highlighted wherever applicable. Moreover, representative examples are given describing the ion transport through biological and synthetic nanopores as well as the high selectivity of ion channels. Special emphasis is placed on the usage of molecular dynamics simulations which already have demonstrated their potential to unravel ion transport properties at an atomic level.

  20. Nanoporous metal oxides with tunable and nanocrystalline frameworks via conversion of metal-organic frameworks.

    Science.gov (United States)

    Kim, Tae Kyung; Lee, Kyung Joo; Cheon, Jae Yeong; Lee, Jae Hwa; Joo, Sang Hoon; Moon, Hoi Ri

    2013-06-19

    Nanoporous metal oxide materials are ubiquitous in the material sciences because of their numerous potential applications in various areas, including adsorption, catalysis, energy conversion and storage, optoelectronics, and drug delivery. While synthetic strategies for the preparation of siliceous nanoporous materials are well-established, nonsiliceous metal oxide-based nanoporous materials still present challenges. Herein, we report a novel synthetic strategy that exploits a metal-organic framework (MOF)-driven, self-templated route toward nanoporous metal oxides via thermolysis under inert atmosphere. In this approach, an aliphatic ligand-based MOF is thermally converted to nanoporous metal oxides with highly nanocrystalline frameworks, in which aliphatic ligands act as the self-templates that are afterward evaporated to generate nanopores. We demonstrate this concept with hierarchically nanoporous magnesia (MgO) and ceria (CeO2), which have potential applicability for adsorption, catalysis, and energy storage. The pore size of these nanoporous metal oxides can be readily tuned by simple control of experimental parameters. Significantly, nanoporous MgO exhibits exceptional CO2 adsorption capacity (9.2 wt %) under conditions mimicking flue gas. This MOF-driven strategy can be expanded to other nanoporous monometallic and multimetallic oxides with a multitude of potential applications.

  1. Controlling molecular transport through nanopores

    Science.gov (United States)

    Keyser, Ulrich F.

    2011-01-01

    Nanopores are emerging as powerful tools for the detection and identification of macromolecules in aqueous solution. In this review, we discuss the recent development of active and passive controls over molecular transport through nanopores with emphasis on biosensing applications. We give an overview of the solutions developed to enhance the sensitivity and specificity of the resistive-pulse technique based on biological and solid-state nanopores. PMID:21715402

  2. Controlling molecular transport through nanopores

    OpenAIRE

    Keyser, Ulrich F.

    2011-01-01

    Nanopores are emerging as powerful tools for the detection and identification of macromolecules in aqueous solution. In this review, we discuss the recent development of active and passive controls over molecular transport through nanopores with emphasis on biosensing applications. We give an overview of the solutions developed to enhance the sensitivity and specificity of the resistive-pulse technique based on biological and solid-state nanopores.

  3. Preparation of nano-porous LiNi0.5Mn1.5O4 with high electrochemical performances by a co-precipitation method for 5 V lithium-ion batteries

    Science.gov (United States)

    Cui, Xiaoling; Li, Hongliang; Li, Shiyou

    2017-10-01

    Porous LiNi0.5Mn1.5O4 is prepared by co-precipitation method. The results of scanning electron microscopy show that the sample has a nano-porous structure. Charge-discharge tests show that the synthesized product exhibits excellent electrochemical performance with a high initial discharge capacity of 129.1 mAh g-1 at 0.5 C and a preferably capacity retention of 96.5% after 200 cycles. The superior performance of the synthesized product is attributed to its nano-porous structure. The nanoparticle reduces the path of Li+ diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge-discharge.

  4. Nanopore sensors for DNA analysis

    DEFF Research Database (Denmark)

    Solovyeva, Vita; Venkatesan, B.M.; Shim, Jeong

    2012-01-01

    Solid-state nanopore sensors are promising devices for single DNA molecule detection and sequencing. This paper presents a review of our work on solid-state nanopores performed over the last decade. In particular, here we discuss atomic-layer-deposited (ALD)-based, graphene-based, and functionali......Solid-state nanopore sensors are promising devices for single DNA molecule detection and sequencing. This paper presents a review of our work on solid-state nanopores performed over the last decade. In particular, here we discuss atomic-layer-deposited (ALD)-based, graphene...

  5. Airfoil noise computation use high-order schemes

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong; Sørensen, Jens Nørkær

    2007-01-01

    ) finite difference schemes and optimized high-order compact finite difference schemes are applied for acoustic computation. Acoustic equations are derived using so-called splitting technique by separating the compressible NS equations into viscous (flow equation) and inviscid (acoustic equation) parts......High-order finite difference schemes with at least 4th-order spatial accuracy are used to simulate aerodynamically generated noise. The aeroacoustic solver with 4th-order up to 8th-order accuracy is implemented into the in-house flow solver, EllipSys2D/3D. Dispersion-Relation-Preserving (DRP...

  6. Encapsulated heterogeneous base catalysts onto SBA-15 nanoporous material as highly active catalysts in the transesterification of sunflower oil to biodiesel

    Science.gov (United States)

    Albayati, Talib M.; Doyle, Aidan M.

    2015-02-01

    Alkali metals and their hydroxides, Na, NaOH, Li, and LiOH, were encapsulated onto SBA-15 nanoporous material as highly active catalysts for the production of biodiesel fuel from sunflower oil. The incipient wetness impregnation method was adopted for the prepared catalysts. The characterization properties of the catalysts and unmodified SBA-15 were determined using X-ray diffraction, scanning electron microscopy, EDAX, nitrogen adsorption-desorption porosimetry (Brunauer-Emmett-Teller), Fourier-transform infrared spectroscopy, and transmission electron microscopy. Transesterification was conducted in a batch reactor at atmospheric pressure and 65 °C. The catalysts were highly active with yields of fatty acid methyl ester (FAME) in the range 96-99 %. Na/SBA-15 catalyst was reused for seven consecutive cycles under the same reaction conditions; the yield to FAME on the final cycle was 96 %. This study shows that the alkali metals and their hydroxides supported on SBA-15-based catalyst are excellent catalysts for the biodiesel reaction.

  7. Encapsulated heterogeneous base catalysts onto SBA-15 nanoporous material as highly active catalysts in the transesterification of sunflower oil to biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Albayati, Talib M., E-mail: talib-albyati@yahoo.com [University of Technology, Department of Chemical Engineering (Iraq); Doyle, Aidan M., E-mail: a.m.doyle@mmu.ac.uk [Manchester Metropolitan University, Division of Chemistry and Environmental Science (United Kingdom)

    2015-02-15

    Alkali metals and their hydroxides, Na, NaOH, Li, and LiOH, were encapsulated onto SBA-15 nanoporous material as highly active catalysts for the production of biodiesel fuel from sunflower oil. The incipient wetness impregnation method was adopted for the prepared catalysts. The characterization properties of the catalysts and unmodified SBA-15 were determined using X-ray diffraction, scanning electron microscopy, EDAX, nitrogen adsorption–desorption porosimetry (Brunauer–Emmett–Teller), Fourier-transform infrared spectroscopy, and transmission electron microscopy. Transesterification was conducted in a batch reactor at atmospheric pressure and 65 °C. The catalysts were highly active with yields of fatty acid methyl ester (FAME) in the range 96–99 %. Na/SBA-15 catalyst was reused for seven consecutive cycles under the same reaction conditions; the yield to FAME on the final cycle was 96 %. This study shows that the alkali metals and their hydroxides supported on SBA-15-based catalyst are excellent catalysts for the biodiesel reaction.

  8. From Metal-Organic Framework to Li2S@C-Co-N Nanoporous Architecture: A High-Capacity Cathode for Lithium-Sulfur Batteries.

    Science.gov (United States)

    He, Jiarui; Chen, Yuanfu; Lv, Weiqiang; Wen, Kechun; Xu, Chen; Zhang, Wanli; Li, Yanrong; Qin, Wu; He, Weidong

    2016-12-27

    Owing to the high theoretical specific capacity (1166 mAh g -1 ), lithium sulfide (Li 2 S) has been considered as a promising cathode material for Li-S batteries. However, the polysulfide dissolution and low electronic conductivity of Li 2 S limit its further application in next-generation Li-S batteries. In this report, a nanoporous Li 2 S@C-Co-N cathode is synthesized by liquid infiltration-evaporation of ultrafine Li 2 S nanoparticles into graphitic carbon co-doped with cobalt and nitrogen (C-Co-N) derived from metal-organic frameworks. The obtained Li 2 S@C-Co-N architecture remarkably immobilizes Li 2 S within the cathode structure through physical and chemical molecular interactions. Owing to the synergistic interactions between C-Co-N and Li 2 S nanoparticles, the Li 2 S@C-Co-N composite delivers a reversible capacity of 1155.3 (99.1% of theoretical value) at the initial cycle and 929.6 mAh g -1 after 300 cycles, with nearly 100% Coulombic efficiency and a capacity fading of 0.06% per cycle. It exhibits excellent rate capacities of 950.6, 898.8, and 604.1 mAh g -1 at 1C, 2C, and 4C, respectively. Such a cathode structure is promising for practical applications in high-performance Li-S batteries.

  9. Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

    OpenAIRE

    Nguyen Duc Hoa; Nguyen Van Duy; Sherif A. El-Safty; Nguyen Van Hieu,

    2015-01-01

    Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas...

  10. Nanoporous TiNb2O7/C Composite Microspheres with Three-Dimensional Conductive Network for Long-Cycle-Life and High-Rate-Capability Anode Materials for Lithium-Ion Batteries.

    Science.gov (United States)

    Zhu, Guozhen; Li, Qing; Zhao, Yunhao; Che, Renchao

    2017-11-29

    On the basis of the advantages of ideal cycling stability, high discharge voltage (1.65 V), and excellent reversibility, more and more attention has been focused on TiNb2O7 (marked as TNO) as an anode material candidate for lithium-ion batteries. However, the poor electronic conductivity and low ionic diffusion rate intrinsically restrict its practical use. Herein, we first synthesize the TNO/C composite microspheres with three-dimensionally (marked as 3D) electro-conductive carbon network and abundant nanoporous structure by a simple spray-drying method. The microspheres are constructed by irregularly primary cubic nanoparticle units with size of 100-200 nm. The nanopores throughout the microspheres range from 1 to 50 nm. As an anode material, the prepared TNO/C composite microspheres demonstrate a prominent charge/discharge capacity of 323.2/326 mA h g-1 after 300 cycles at 0.25 C (1 C = 388 mA g-1) and 259.9/262.5 mA h g-1 after 1000 long cycles at a high current density of 5 C, revealing the ideal reversible capacity and long cycling life. Meanwhile, the TNO/C composite microspheres present ideal rate performance, showing the discharge capacity of 120 mA h g-1 at 30 C after 10 cycles. The super electrochemical performance could be attributed to the 3D electro-conductive carbon network and nanoporous structure. The nanopores facilitate the permeation of electrolyte into the intercontacting regions of the anode materials. Carbon layers disperse uniformly throughout the 3D microspheres, effectively improving the electrical conductivity of the electrode. Hence, the prepared TNO/C composite microspheres have great potential to be used as an anode material for lithium-ion batteries.

  11. Highly Reversible and Durable Na Storage in Niobium Pentoxide through Optimizing Structure, Composition, and Nanoarchitecture.

    Science.gov (United States)

    Ni, Jiangfeng; Wang, Wencong; Wu, Chao; Liang, Haichen; Maier, Joachim; Yu, Yan; Li, Liang

    2017-03-01

    Amorphous, hydrogenated, and self-ordered nanoporous Nb 2 O 5 films serve as an excellent binder-free electrode for sodium batteries, affording a high and sustainable capacity delivery and robust high-rate capability. This collaborative material engineering of structural order (amorphization), composition (hydrogenation), and architecture (ordered nanopore) opens up new possibilities to develop an energy storage solution that is more accessible, sustainable, and producible. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. The high-order Boltzmann machine: learned distribution and topology.

    Science.gov (United States)

    Albizuri, F X; Danjou, A; Grana, M; Torrealdea, J; Hernandez, M C

    1995-01-01

    In this paper we give a formal definition of the high-order Boltzmann machine (BM), and extend the well-known results on the convergence of the learning algorithm of the two-order BM. From the Bahadur-Lazarsfeld expansion we characterize the probability distribution learned by the high order BM. Likewise a criterion is given to establish the topology of the BM depending on the significant correlations of the particular probability distribution to be learned.

  13. High-order-harmonic generation from field-distorted orbitals

    DEFF Research Database (Denmark)

    Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer

    2013-01-01

    We investigate the effect on high-order-harmonic generation of the distortion of molecular orbitals by the driving laser field. Calculations for high-order-harmonic generation including orbital distortion are performed for N2. Our results allow us to suggest that field distortion is the reason why...

  14. Optimized nanoporous materials.

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Paul V. (University of Illinois at Urbana-Champaign, Urbana, IL); Langham, Mary Elizabeth; Jacobs, Benjamin W.; Ong, Markus D.; Narayan, Roger J. (North Carolina State University, Raleigh, NC); Pierson, Bonnie E. (North Carolina State University, Raleigh, NC); Gittard, Shaun D. (North Carolina State University, Raleigh, NC); Robinson, David B.; Ham, Sung-Kyoung (Korea Basic Science Institute, Gangneung, South Korea); Chae, Weon-Sik (Korea Basic Science Institute, Gangneung, South Korea); Gough, Dara V. (University of Illinois at Urbana-Champaign, Urbana, IL); Wu, Chung-An Max; Ha, Cindy M.; Tran, Kim L.

    2009-09-01

    Nanoporous materials have maximum practical surface areas for electrical charge storage; every point in an electrode is within a few atoms of an interface at which charge can be stored. Metal-electrolyte interfaces make best use of surface area in porous materials. However, ion transport through long, narrow pores is slow. We seek to understand and optimize the tradeoff between capacity and transport. Modeling and measurements of nanoporous gold electrodes has allowed us to determine design principles, including the fact that these materials can deplete salt from the electrolyte, increasing resistance. We have developed fabrication techniques to demonstrate architectures inspired by these principles that may overcome identified obstacles. A key concept is that electrodes should be as close together as possible; this is likely to involve an interpenetrating pore structure. However, this may prove extremely challenging to fabricate at the finest scales; a hierarchically porous structure can be a worthy compromise.

  15. Nanotechnology and Nanopore Sequencing.

    Science.gov (United States)

    Abedini-Nassab, Roozbeh

    2017-01-01

    DNA sequencing is one of the crucially important tasks in the fields of genetics and cellular biology, which is benefiting from nanotechnology. DNA carries genetic information and sequencing it in a quick way helps researchers in achieving essential goals, including personalized medicine. Solid state nanopores potentially can offer more durability, in sequencing biomolecules, over the proteinbased nanopores. In recent years, various ideas are introduced towards the goal of fast and low cost sequencing. In this review article recent advances presented in journal articles as well as patents in this field, including sequencing methods, membrane materials and their fabrication techniques, drilling methods, and biomolecule translocation speed control ideas are investigated. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Highly efficient direct aerobic oxidative esterification of cinnamyl alcohol with alkyl alcohols catalysed by gold nanoparticles incarcerated in a nanoporous polymer matrix: a tool for investigating the role of the polymer host.

    Science.gov (United States)

    Buonerba, Antonio; Noschese, Annarita; Grassi, Alfonso

    2014-04-25

    The selective aerobic oxidation of cinnamyl alcohol to cinnamaldehyde, as well as direct oxidative esterification of this alcohol with primary and secondary aliphatic alcohols, were achieved with high chemoselectivity by using gold nanoparticles supported in a nanoporous semicrystalline multi-block copolymer matrix, which consisted of syndiotactic polystyrene-co-cis-1,4-polybutadiene. The cascade reaction that leads to the alkyl cinnamates occurs through two oxidation steps: the selective oxidation of cinnamyl alcohol to cinnamaldehyde, followed by oxidation of the hemiacetal that results from the base-catalysed reaction of cinnamaldehyde with an aliphatic alcohol. The rate constants for the two steps were evaluated in the temperature range 10-45 °C. The cinnamyl alcohol oxidation is faster than the oxidative esterification of cinnamaldehyde with methanol, ethanol, 2-propanol, 1-butanol, 1-hexanol or 1-octanol. The rate constants of the latter reaction are pseudo-zero order with respect to the aliphatic alcohol and decrease as the bulkiness of the alcohol is increased. The activation energy (Ea) for the two oxidation steps was calculated for esterification of cinnamyl alcohol with 1-butanol (Ea = 57.8±11.5 and 62.7±16.7 kJ mol(-1) for the first and second step, respectively). The oxidative esterification of cinnamyl alcohol with 2-phenylethanol follows pseudo-first-order kinetics with respect to 2-phenylethanol and is faster than observed for other alcohols because of fast diffusion of the aromatic alcohol in the crystalline phase of the support. The kinetic investigation allowed us to assess the role of the polymer support in the determination of both high activity and selectivity in the title reaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Nanoporous PdZr surface alloy as highly active non-platinum electrocatalyst toward oxygen reduction reaction with unique structure stability and methanol-tolerance

    Science.gov (United States)

    Duan, Huimei; Xu, Caixia

    2016-06-01

    Nanoporous (NP) PdZr alloy with controllable bimetallic ratio is successfully fabricated by a simple dealloying method. By leaching out the more reactive Al from PdZrAl precursor alloy, NP-PdZr alloy with smaller ligament size was generated, characterized by the nanoscaled interconnected network skeleton and hollow channels extending in all three dimensions. Upon voltammetric scan in acid solution, the dissolution of surface Zr atoms generates the highly active Pd-Zr surface alloy with a nearly pure Pd surface and Pd-Zr alloy core. The NP-Pd80Zr20 surface alloy exhibits markedly enhanced specific and mass activities as well as higher catalytic stability toward oxygen reduction reaction (ORR) compared with NP-Pd and the state-of-the-art Pt/C catalysts. In addition, the NP-Pd80Zr20 surface alloy shows a better selectivity for ORR than methanol in the 0.1 M HClO4 and 0.1 M methanol mixed solution. X-ray photoelectron spectroscopy and density functional theory calculations both demonstrate that the weakened Pd-O bond and improved ORR performances in turn depend on the downshifted d-band center of Pd due to the alloying Pd with Zr (20 at.%). The as-made NP-PdZr alloy holds prospective applications as a cathode electrocatalyst in fuel-cell-related technologies with the advantages of superior overall ORR performances, unique structure stability, and easy preparation.

  18. Single-molecule nanopore enzymology

    NARCIS (Netherlands)

    Willems, Kherim; Van Meervelt, Veerle; Wloka, Carsten; Maglia, Giovanni

    2017-01-01

    Biological nanopores are a class of membrane proteins that open nanoscale water conduits in biological membranes. When they are reconstituted in artificial membranes and a bias voltage is applied across the membrane, the ionic current passing through individual nanopores can be used to monitor

  19. Efficient Unsteady Flow Visualization with High-Order Access Dependencies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiang; Guo, Hanqi; Yuan, Xiaoru

    2016-04-19

    We present a novel high-order access dependencies based model for efficient pathline computation in unsteady flow visualization. By taking longer access sequences into account to model more sophisticated data access patterns in particle tracing, our method greatly improves the accuracy and reliability in data access prediction. In our work, high-order access dependencies are calculated by tracing uniformly-seeded pathlines in both forward and backward directions in a preprocessing stage. The effectiveness of our proposed approach is demonstrated through a parallel particle tracing framework with high-order data prefetching. Results show that our method achieves higher data locality and hence improves the efficiency of pathline computation.

  20. The Development of High Order Methods for Real World Applications

    Science.gov (United States)

    2015-12-03

    three-stage 3rd order Runge-Kutta scheme Gottlieb and Shu [43] is used as the temporal discretization. Here we give a brief description. Rewrite the...Science and Engineering. Springer Berlin Heidelberg, pp. 47–95. [43] Gottlieb , S., Shu, C.-W., 2011. Strong stability-preserving high-order time dis

  1. Streaming current magnetic fields in a charged nanopore

    Science.gov (United States)

    Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W.

    2016-01-01

    Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques. PMID:27833119

  2. Membrane Curvature Affects the Formation of α-Hemolysin Nanopores.

    Science.gov (United States)

    Fujii, Satoshi; Matsuura, Tomoaki; Yomo, Tetsuya

    2015-07-17

    Membrane proteins perform their functions within or on the lipid membrane, and lipid compositions are known to affect membrane protein integration and activity. Recently, the geometric aspect of membrane curvature was shown to play an important role in membrane protein behavior. Certain membrane proteins are known to sense the curvature of the membrane and to preferentially bind to highly curved membranes. However, although numerous membrane proteins assemble to form homo- or heterocomplexes and perform their biological functions, the dependence of membrane protein assembly on membrane curvature remains elusive. In this study, we analyzed the effect of the membrane curvature on the nanopore formation of α-hemolysin (AH), which is a toxic membrane protein derived from Staphylococcus aureus. The AH protein binds to the membrane as a monomer, assembles to form a heptamer, and forms a nanopore. By simultaneously measuring the molecules bound to the membrane and the activities of the nanopore on the membrane, we determined the nanopore formation ratio of AH. We used various sizes of liposomes and analyzed the dependence on the membrane curvature by using flow cytometry. Combining the results for positive and negative curvature, we found that the nanopore formation ratio of AH was curvature sensitive and was higher in a flat membrane than in a curved membrane. Furthermore, the nanopore formation ratio was almost identical or relatively higher in membranes with negative curvature than those with positive curvature.

  3. Electrochemical Hydrogen Storage in a Highly Ordered Mesoporous Carbon

    OpenAIRE

    Dan eLiu; Chao eZeng; Haolin eTan; Dong eZheng; Rong eLi; Deyu eQu; zhizhong eXie; Jiahen eLei; Liang eXiao; Deyang eQu

    2014-01-01

    A highly ordered mesoporous carbon (HOMC) has been synthesized through a strongly acidic, aqueous cooperative assembly route. The structure and morphology of the carbon material were investigated using TEM, SEM, and nitrogen adsorption–desorption isotherms. The carbon was proven to be meso-structural and consisted of graphitic micro-domain with larger interlayer space. Active carbon impedance and electrochemical measurements reveal that the synthesized highly ordered mesoporous carbon (HOMC) ...

  4. Where bio meets nano: The many uses for nanoporous aluminium oxide in biotechnology

    NARCIS (Netherlands)

    Ingham, C.J.; Maat, ter J.; Vos, de W.M.

    2012-01-01

    Porous aluminum oxide (PAO) is a ceramic formed by an anodization process of pure aluminum that enables the controllable assembly of exceptionally dense and regular nanopores in a planar membrane. As a consequence, PAO has a high porosity, nanopores with high aspect ratio, biocompatibility and the

  5. Solar multi-conjugate adaptive optics based on high order ground layer adaptive optics and low order high altitude correction.

    Science.gov (United States)

    Zhang, Lanqiang; Guo, Youming; Rao, Changhui

    2017-02-20

    Multi-conjugate adaptive optics (MCAO) is the most promising technique currently developed to enlarge the corrected field of view of adaptive optics for astronomy. In this paper, we propose a new configuration of solar MCAO based on high order ground layer adaptive optics and low order high altitude correction, which result in a homogeneous correction effect in the whole field of view. An individual high order multiple direction Shack-Hartmann wavefront sensor is employed in the configuration to detect the ground layer turbulence for low altitude correction. Furthermore, the other low order multiple direction Shack-Hartmann wavefront sensor supplies the wavefront information caused by high layers' turbulence through atmospheric tomography for high altitude correction. Simulation results based on the system design at the 1-meter New Vacuum Solar Telescope show that the correction uniform of the new scheme is obviously improved compared to conventional solar MCAO configuration.

  6. Biological Nanopores: Confined Spaces for Electrochemical Single-Molecule Analysis.

    Science.gov (United States)

    Cao, Chan; Long, Yi-Tao

    2018-02-20

    Nanopore sensing is developing into a powerful single-molecule approach to investigate the features of biomolecules that are not accessible by studying ensemble systems. When a target molecule is transported through a nanopore, the ions occupying the pore are excluded, resulting in an electrical signal from the intermittent ionic blockade event. By statistical analysis of the amplitudes, duration, frequencies, and shapes of the blockade events, many properties of the target molecule can be obtained in real time at the single-molecule level, including its size, conformation, structure, charge, geometry, and interactions with other molecules. With the development of the use of α-hemolysin to characterize individual polynucleotides, nanopore technology has attracted a wide range of research interest in the fields of biology, physics, chemistry, and nanoscience. As a powerful single-molecule analytical method, nanopore technology has been applied for the detection of various biomolecules, including oligonucleotides, peptides, oligosaccharides, organic molecules, and disease-related proteins. In this Account, we highlight recent developments of biological nanopores in DNA-based sensing and in studying the conformational structures of DNA and RNA. Furthermore, we introduce the application of biological nanopores to investigate the conformations of peptides affected by charge, length, and dipole moment and to study disease-related proteins' structures and aggregation transitions influenced by an inhibitor, a promoter, or an applied voltage. To improve the sensing ability of biological nanopores and further extend their application to a wider range of molecular sensing, we focus on exploring novel biological nanopores, such as aerolysin and Stable Protein 1. Aerolysin exhibits an especially high sensitivity for the detection of single oligonucleotides both in current separation and duration. Finally, to facilitate the use of nanopore measurements and statistical analysis

  7. Gel mesh as ``brake'' to slow down DNA translocation through solid-state nanopores

    Science.gov (United States)

    Tang, Zhipeng; Liang, Zexi; Lu, Bo; Li, Ji; Hu, Rui; Zhao, Qing; Yu, Dapeng

    2015-07-01

    Agarose gel is introduced onto the cis side of silicon nitride nanopores by a simple and low-cost method to slow down the speed of DNA translocation. DNA translocation speed is slowed by roughly an order of magnitude without losing signal to noise ratio for different DNA lengths and applied voltages in gel-meshed nanopores. The existence of the gel moves the center-of-mass position of the DNA conformation further from the nanopore center, contributing to the observed slowing of translocation speed. A reduced velocity fluctuation is also noted, which is beneficial for further applications of gel-meshed nanopores. The reptation model is considered in simulation and agrees well with the experimental results.Agarose gel is introduced onto the cis side of silicon nitride nanopores by a simple and low-cost method to slow down the speed of DNA translocation. DNA translocation speed is slowed by roughly an order of magnitude without losing signal to noise ratio for different DNA lengths and applied voltages in gel-meshed nanopores. The existence of the gel moves the center-of-mass position of the DNA conformation further from the nanopore center, contributing to the observed slowing of translocation speed. A reduced velocity fluctuation is also noted, which is beneficial for further applications of gel-meshed nanopores. The reptation model is considered in simulation and agrees well with the experimental results. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03084f

  8. A high order solver for the unbounded Poisson equation

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Rasmussen, Johannes Tophøj; Chatelain, Philippe

    In mesh-free particle methods a high order solution to the unbounded Poisson equation is usually achieved by constructing regularised integration kernels for the Biot-Savart law. Here the singular, point particles are regularised using smoothed particles to obtain an accurate solution with an order...... of convergence consistent with the moments conserved by the applied smoothing function. In the hybrid particle-mesh method of Hockney and Eastwood (HE) the particles are interpolated onto a regular mesh where the unbounded Poisson equation is solved by a discrete non-cyclic convolution of the mesh values...... and the integration kernel. In this work we show an implementation of high order regularised integration kernels in the HE algorithm for the unbounded Poisson equation to formally achieve an arbitrary high order convergence. We further present a quantitative study of the convergence rate to give further insight...

  9. Conversion of Isoprenoid Oil by Catalytic Cracking and Hydrocracking over Nanoporous Hybrid Catalysts

    Science.gov (United States)

    Kimura, Toshiyuki; Liu, Chen; Li, Xiaohong; Maekawa, Takaaki; Asaoka, Sachio

    2012-01-01

    In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al2O3/H-USY and ns Al2O3/H-GaAlMFI; HC: [Ni-Mo/γ-Al2O3]/ns Al2O3/H-beta) were studied. The major product from CC on ns Al2O3/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50 wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80 wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products. PMID:22791962

  10. Conversion of isoprenoid oil by catalytic cracking and hydrocracking over nanoporous hybrid catalysts.

    Science.gov (United States)

    Kimura, Toshiyuki; Liu, Chen; Li, Xiaohong; Maekawa, Takaaki; Asaoka, Sachio

    2012-01-01

    In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al₂O₃ and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al₂O₃/H-USY and ns Al₂O₃/H-GaAlMFI; HC: [Ni-Mo/γ-Al₂O₃]/ns Al₂O₃/H-beta) were studied. The major product from CC on ns Al₂O₃/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50 wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80 wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products.

  11. Conversion of Isoprenoid Oil by Catalytic Cracking and Hydrocracking over Nanoporous Hybrid Catalysts

    Directory of Open Access Journals (Sweden)

    Toshiyuki Kimura

    2012-01-01

    Full Text Available In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT, hydrocracking (HC, and catalytic cracking (CC of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al2O3/H-USY and ns Al2O3/H-GaAlMFI; HC: [Ni-Mo/γ-Al2O3]/ns Al2O3/H-beta were studied. The major product from CC on ns Al2O3/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50 wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80 wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products.

  12. High power, higher order ultrafast hollow Gaussian beams

    Science.gov (United States)

    Apurv Chaitanya, N.; Amrit Chaitanya, Banerji, J.; Samanta, G. K.

    2017-05-01

    We report on linear and nonlinear generation of ultrafast hollow Gaussian beams (HGBs). Using only two spiral phase plates (SPPs) having phase variation corresponding to vortex orders, l = 1 and 2, and an experimental scheme, we have generated high power, ultrafast HGBs of orders up to 3 at 1064 nm. Based on single-pass, frequency doubling of the HGBs in a 5 mm long, MgO doped, periodically poled LiNbO3 (MgO:PPLN) crystal, we have produced HGBs of average output power in excess of 250 mW at 532 nm and order as high as 6. Experimentally, we verified that the frequency doubled HGBs have orders twice those of the pump HGBs. Like the Gaussian beams, the HGBs of all orders have an optimum focusing condition for the highest conversion efficiency. On the contrary to previous reports, we observed that the propagation of the vortex beam of order, l, through a SPP corresponding to the vortex order of, -l, results in HGBs of the same order, | l | .

  13. High order variational solutions of time dependent neutron transport problems

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, B.C.

    1985-01-01

    High order numerical solutions of the time-dependent one speed neutron transport equation are developed using cubic hermite polynomial trial functions, variational techniques, and exponential matrix operators. Two new numerical solutions are developed that are high order with respect to both time and space variables. In the first method, the time-dependent P/sub N/ equations are transformed into Generalized Telegrapher's Equations (GTE) that are valid for any order P/sub N/ approximation. The Generalized Telegrapher's Equations form a coupled set of second order differential equations with respect to both time and space. In the second method, the time-dependent P/sub N/ equations are transformed into coupled Transport Diffusion Equations (TDE), keeping the additional terms that maintain the transport nature of the solution. The Transport Diffusion Equations are first order in time and second order in space. Numerically evaluated time-dependent analytic solutions are also developed for homogeneous media transport problems in the P/sub 1/ and P/sub 3/ approximations via Laplace Transforms in order to validate the variational GTE and TDE solutions. The analytic solutions allow anisotropic scattering, up to the appropriate P/sub N/ order. The analytic solutions are not limited to the non-precise extrapolation boundary condition, like many time-dependent analytic P/sub N/ solutions, but allow any of the standard transport vacuum boundary condition approximations.

  14. Efficiency of High Order Spectral Element Methods on Petascale Architectures

    KAUST Repository

    Hutchinson, Maxwell

    2016-06-14

    High order methods for the solution of PDEs expose a tradeoff between computational cost and accuracy on a per degree of freedom basis. In many cases, the cost increases due to higher arithmetic intensity while affecting data movement minimally. As architectures tend towards wider vector instructions and expect higher arithmetic intensities, the best order for a particular simulation may change. This study highlights preferred orders by identifying the high order efficiency frontier of the spectral element method implemented in Nek5000 and NekBox: the set of orders and meshes that minimize computational cost at fixed accuracy. First, we extract Nek’s order-dependent computational kernels and demonstrate exceptional hardware utilization by hardware-aware implementations. Then, we perform productionscale calculations of the nonlinear single mode Rayleigh-Taylor instability on BlueGene/Q and Cray XC40-based supercomputers to highlight the influence of the architecture. Accuracy is defined with respect to physical observables, and computational costs are measured by the corehour charge of the entire application. The total number of grid points needed to achieve a given accuracy is reduced by increasing the polynomial order. On the XC40 and BlueGene/Q, polynomial orders as high as 31 and 15 come at no marginal cost per timestep, respectively. Taken together, these observations lead to a strong preference for high order discretizations that use fewer degrees of freedom. From a performance point of view, we demonstrate up to 60% full application bandwidth utilization at scale and achieve ≈1PFlop/s of compute performance in Nek’s most flop-intense methods.

  15. Enhanced high-order harmonic generation from Argon-clusters

    NARCIS (Netherlands)

    Tao, Yin; Hagmeijer, Rob; Bastiaens, Hubertus M.J.; Goh, S.J.; van der Slot, P.J.M.; Biedron, S.; Milton, S.; Boller, Klaus J.

    2017-01-01

    High-order harmonic generation (HHG) in clusters is of high promise because clusters appear to offer an increased optical nonlinearity. We experimentally investigate HHG from Argon clusters in a supersonic gas jet that can generate monomer-cluster mixtures with varying atomic number density and

  16. Parallel preconditioners and high order elements for microwave imaging

    CERN Document Server

    Bonazzoli, M; Rapetti, F; Tournier, P -H

    2016-01-01

    This paper combines the use of high order finite element methods with parallel preconditioners of domain decomposition type for solving electromagnetic problems arising from brain microwave imaging. The numerical algorithms involved in such complex imaging systems are computationally expensive since they require solving the direct problem of Maxwell's equations several times. Moreover, wave propagation problems in the high frequency regime are challenging because a sufficiently high number of unknowns is required to accurately represent the solution. In order to use these algorithms in practice for brain stroke diagnosis, running time should be reasonable. The method presented in this paper, coupling high order finite elements and parallel preconditioners, makes it possible to reduce the overall computational cost and simulation time while maintaining accuracy.

  17. Separation of High Order Harmonics with Fluoride Windows

    Energy Technology Data Exchange (ETDEWEB)

    Allison, Tom; van Tilborg, Jeroen; Wright, Travis; Hertlein, Marcus; Falcone, Roger; Belkacem, Ali

    2010-08-02

    The lower orders produced in high order harmonic generation can be effciently temporally separated into monochromatic pulses by propagation in a Fluoride window while still preserving their femtosecond pulse duration. We present calculations for MgF2, CaF2, and LiF windows for the third, fifth, and seventh harmonics of 800 nm. We demonstrate the use of this simple and inexpensive technique in a femtosecond pump/probe experiment using the fifth harmonic.

  18. Hyperspectral target detection using regularized high-order matched filter

    Science.gov (United States)

    Shi, Zhenwei; Yang, Shuo; Jiang, Zhiguo

    2011-05-01

    Automatic target detection is an important application in the hyperspectral image processing field. Most statistics-based detection algorithms use second-order statistics to construct detectors. However, for target detection in a real hyperspectral image, targets of interest usually occupy a few pixels with small population. In this case, high-order statistics could characterize targets more effectively than second-order statistics. Also, the inherent variation of spectra of targets is an obstacle to successful target detection. In this paper, we propose a regularized high-order matched filter (RHF) which uses high-order statistics to build an objective function and uses a regularized term to make the algorithm robust to target spectral variation. A gradient descent method is used to solve this optimization problem, and we obtain the convergence properties of the RHF. According to the experimental hyperspectral data, the results have shown that the proposed algorithm performed better than those classical second-order statistics-based algorithms and some kernel-based methods.

  19. Nanoporous carbon sorbent for molecular-sieve chromatography of lipoprotein complex

    Science.gov (United States)

    Kerimkulova, A. R.; Mansurova, B. B.; Gil'manov, M. K.; Mansurov, Z. A.

    2012-06-01

    The physicochemical characteristics of carbon sorbents are investigated. Electron microscopy data for the sorbent and separated lipoprotein complex are presented. It is found that the obtained carbon sorbent possess high porosity. Nanoporous carbon sorbents for the chromatography of molecular-sieve markers are obtained and tested. The applicability of nanoporous carbon sorbents for separation of lipoprotein complexes (LPC) is investigated.

  20. Electrochemical Hydrogen Storage in a Highly Ordered Mesoporous Carbon

    Directory of Open Access Journals (Sweden)

    Dan eLiu

    2014-10-01

    Full Text Available A highly order mesoporous carbon has been synthesized through a strongly acidic, aqueous cooperative assembly route. The structure and morphology of the carbon material were investigated using TEM, SEM and nitrogen adsorption-desorption isotherms. The carbon was proven to be meso-structural and consisted of graphitic micro-domain with larger interlayer space. AC impedance and electrochemical measurements reveal that the synthesized highly ordered mesoporous carbon exhibits a promoted electrochemical hydrogen insertion process and improved capacitance and hydrogen storage stability. The meso-structure and enlarged interlayer distance within the highly ordered mesoporous carbon are suggested as possible causes for the enhancement in hydrogen storage. Both hydrogen capacity in the carbon and mass diffusion within the matrix were improved.

  1. A high order solver for the unbounded Poisson equation

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Rasmussen, Johannes Tophøj; Chatelain, Philippe

    2013-01-01

    . The method is extended to directly solve the derivatives of the solution to Poissonʼs equation. In this way differential operators such as the divergence or curl of the solution field can be solved to the same high order convergence without additional computational effort. The method, is applied...... and validated, however not restricted, to the equations of fluid mechanics, and can be used in many applications to solve Poissonʼs equation on a rectangular unbounded domain.......A high order converging Poisson solver is presented, based on the Greenʼs function solution to Poissonʼs equation subject to free-space boundary conditions. The high order convergence is achieved by formulating regularised integration kernels, analogous to a smoothing of the solution field...

  2. Dynamic Stability Analysis Using High-Order Interpolation

    Directory of Open Access Journals (Sweden)

    Juarez-Toledo C.

    2012-10-01

    Full Text Available A non-linear model with robust precision for transient stability analysis in multimachine power systems is proposed. The proposed formulation uses the interpolation of Lagrange and Newton's Divided Difference. The High-Order Interpolation technique developed can be used for evaluation of the critical conditions of the dynamic system.The technique is applied to a 5-area 45-machine model of the Mexican interconnected system. As a particular case, this paper shows the application of the High-Order procedure for identifying the slow-frequency mode for a critical contingency. Numerical examples illustrate the method and demonstrate the ability of the High-Order technique to isolate and extract temporal modal behavior.

  3. Atomic layer deposition of TiO2 thin films on nanoporous alumina templates: Medical applications

    Science.gov (United States)

    Narayan, Roger J.; Monteiro-Riviere, Nancy A.; Brigmon, Robin L.; Pellin, Michael J.; Elam, Jeffrey W.

    2009-06-01

    Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of a nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Neither the 20 nm nor the 100 nm TiO2-coated nanoporous alumina membranes exhibited statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. Nanostructured materials prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for “smart” drug delivery devices, orthopedic implants, or self-sterilizing medical devices.

  4. A Humidity Sensor Based on Nb-doped Nanoporous TiO2 Thin Film

    Directory of Open Access Journals (Sweden)

    Mansoor Anbia

    2011-11-01

    Full Text Available The humidity sensing properties of the sensor fabricated from Nb-doped nanoporous TiO2 by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes have been investigated. The nanoporous thin film has been prepared by sol-gel technique. The product has been characterized by X-ray diffraction and scanning electron microscopy to analyze the structure and its morphology. It is found that the impedance of this sensor changes more than four orders of magnitude in the relative humidity (RH range of 11–95 % at 25 °C. The response and recovery time of the sensor are about 19 and 25 s, respectively, during the RH variation from 11 to 95 %. The sensor shows high humidity sensitivity, rapid response and recovery, prominent stability, good repeatability and narrow hysteresis loop. These results indicate that Nb-doped nanoporous TiO2 thin films have a great potential for humidity sensing applications in room temperature operations.

  5. Use of high order, periodic orbits in the PIES code

    Science.gov (United States)

    Monticello, Donald; Reiman, Allan

    2010-11-01

    We have implemented a version of the PIES code (Princeton Iterative Equilibrium SolverootnotetextA. Reiman et al 2007 Nucl. Fusion 47 572) that uses high order periodic orbits to select the surfaces on which straight magnetic field line coordinates will be calculated. The use of high order periodic orbits has increase the robustness and speed of the PIES code. We now have more uniform treatment of in-phase and out-of-phase islands. This new version has better convergence properties and works well with a full Newton scheme. We now have the ability to shrink islands using a bootstrap like current and this includes the m=1 island in tokamaks.

  6. High-Order Curvilinear Finite Element Methods for Lagrangian Hydrodynamics [High Order Curvilinear Finite Elements for Lagrangian Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Dobrev, Veselin A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kolev, Tzanio V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rieben, Robert N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-09-20

    The numerical approximation of the Euler equations of gas dynamics in a movingLagrangian frame is at the heart of many multiphysics simulation algorithms. Here, we present a general framework for high-order Lagrangian discretization of these compressible shock hydrodynamics equations using curvilinear finite elements. This method is an extension of the approach outlined in [Dobrev et al., Internat. J. Numer. Methods Fluids, 65 (2010), pp. 1295--1310] and can be formulated for any finite dimensional approximation of the kinematic and thermodynamic fields, including generic finite elements on two- and three-dimensional meshes with triangular, quadrilateral, tetrahedral, or hexahedral zones. We discretize the kinematic variables of position and velocity using a continuous high-order basis function expansion of arbitrary polynomial degree which is obtained via a corresponding high-order parametric mapping from a standard reference element. This enables the use of curvilinear zone geometry, higher-order approximations for fields within a zone, and a pointwise definition of mass conservation which we refer to as strong mass conservation. Moreover, we discretize the internal energy using a piecewise discontinuous high-order basis function expansion which is also of arbitrary polynomial degree. This facilitates multimaterial hydrodynamics by treating material properties, such as equations of state and constitutive models, as piecewise discontinuous functions which vary within a zone. To satisfy the Rankine--Hugoniot jump conditions at a shock boundary and generate the appropriate entropy, we introduce a general tensor artificial viscosity which takes advantage of the high-order kinematic and thermodynamic information available in each zone. Finally, we apply a generic high-order time discretization process to the semidiscrete equations to develop the fully discrete numerical algorithm. Our method can be viewed as the high-order generalization of the so-called staggered

  7. Fabrication of Low Noise Borosilicate Glass Nanopores for Single Molecule Sensing.

    Directory of Open Access Journals (Sweden)

    Jayesh A Bafna

    Full Text Available We show low-cost fabrication and characterization of borosilicate glass nanopores for single molecule sensing. Nanopores with diameters of ~100 nm were fabricated in borosilicate glass capillaries using laser assisted glass puller. We further achieve controlled reduction and nanometer-size control in pore diameter by sculpting them under constant electron beam exposure. We successfully fabricate pore diameters down to 6 nm. We next show electrical characterization and low-noise behavior of these borosilicate nanopores and compare their taper geometries. We show, for the first time, a comprehensive characterization of glass nanopore conductance across six-orders of magnitude (1M-1μM of salt conditions, highlighting the role of buffer conditions. Finally, we demonstrate single molecule sensing capabilities of these devices with real-time translocation experiments of individual λ-DNA molecules. We observe distinct current blockage signatures of linear as well as folded DNA molecules as they undergo voltage-driven translocation through the glass nanopores. We find increased signal to noise for single molecule detection for higher trans-nanopore driving voltages. We propose these nanopores will expand the realm of applications for nanopore platform.

  8. Large apparent electric size of solid-state nanopores due to spatially extended surface conduction.

    Science.gov (United States)

    Lee, Choongyeop; Joly, Laurent; Siria, Alessandro; Biance, Anne-Laure; Fulcrand, Rémy; Bocquet, Lydéric

    2012-08-08

    Ion transport through nanopores drilled in thin membranes is central to numerous applications, including biosensing and ion selective membranes. This paper reports experiments, numerical calculations, and theoretical predictions demonstrating an unexpectedly large ionic conduction in solid-state nanopores, taking its origin in anomalous entrance effects. In contrast to naive expectations based on analogies with electric circuits, the surface conductance inside the nanopore is shown to perturb the three-dimensional electric current streamlines far outside the nanopore in order to meet charge conservation at the pore entrance. This unexpected contribution to the ionic conductance can be interpreted in terms of an apparent electric size of the solid-state nanopore, which is much larger than its geometric counterpart whenever the number of charges carried by the nanopore surface exceeds its bulk counterpart. This apparent electric size, which can reach hundreds of nanometers, can have a major impact on the electrical detection of translocation events through nanopores, as well as for ionic transport in biological nanopores.

  9. A high order theory for uniform and laminated plates

    Science.gov (United States)

    Lo, K. H.; Christensen, R. M.; Wu, E. M.

    1976-01-01

    A theory of plate deformation is derived which accounts for the effects of transverse shear deformation, transverse normal strain, and a nonlinear distribution of the in-plane displacements with respect to the thickness coordinate. The theory is compared with lower order plate theories through application to a particular problem involving a plate acted upon by a sinusoidal surface pressure. Comparison is also made with exact elasticity solution of this problem. It is found that when the ratio of the characteristic length of the load pattern to the plate thickness is of the order of unity, lower order theories are inadequate and the present high order theory is required to give meaningful results. Results are given for the bending of symmetric cross-ply and angle-ply laminates. Comparison with exact elasticity solutions indicates that the present plate theory is sufficiently accurate for predicting the behavior of thick laminates.

  10. Study of high-order harmonic generation from nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, H; Naik, P A; Srivastava, A K; Singh, A; Chari, R; Khan, R A; Chakera, J A; Gupta, P D [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Ganeev, R A, E-mail: himanshu@rrcat.gov.i [Institute of Electronics, Uzbekistan Academy of Sciences, Tashkent 100125 (Uzbekistan)

    2010-01-28

    An experimental study on high-order harmonic generation from the interaction of 45 fs Ti:sapphire laser pulses with preformed plasma plumes of metal nanoparticles was carried out. Highly efficient harmonic generation in the range of 9th order to 19th order was observed for Ag nanoparticles. The stability of harmonic generation was enhanced by utilizing special target fabrication techniques and through optimizing the conditions of plasma plume formation. Broadband harmonic generation was observed through the optimization of femtosecond laser intensity and through the use of spectrally broadened laser pulses. The harmonic generation was compared for various target materials (nano and bulk) and for Ag nanoparticle targets prepared from different fabrication techniques. Efficient generation of even- and odd-order harmonics was observed through the use of two-colour pulses. The observations can be explained qualitatively from symmetry breaking of high-order harmonic generation through the introduction of second harmonic pulses. The spectral broadening and shift of harmonic radiation can be understood from the self-modulation of the laser and harmonic radiation in the plasma.

  11. Hybrid RANS-LES using high order numerical methods

    Science.gov (United States)

    Henry de Frahan, Marc; Yellapantula, Shashank; Vijayakumar, Ganesh; Knaus, Robert; Sprague, Michael

    2017-11-01

    Understanding the impact of wind turbine wake dynamics on downstream turbines is particularly important for the design of efficient wind farms. Due to their tractable computational cost, hybrid RANS/LES models are an attractive framework for simulating separation flows such as the wake dynamics behind a wind turbine. High-order numerical methods can be computationally efficient and provide increased accuracy in simulating complex flows. In the context of LES, high-order numerical methods have shown some success in predictions of turbulent flows. However, the specifics of hybrid RANS-LES models, including the transition region between both modeling frameworks, pose unique challenges for high-order numerical methods. In this work, we study the effect of increasing the order of accuracy of the numerical scheme in simulations of canonical turbulent flows using RANS, LES, and hybrid RANS-LES models. We describe the interactions between filtering, model transition, and order of accuracy and their effect on turbulence quantities such as kinetic energy spectra, boundary layer evolution, and dissipation rate. This work was funded by the U.S. Department of Energy, Exascale Computing Project, under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory.

  12. Improving the Accuracy of High-Order Nodal Transport Methods

    Energy Technology Data Exchange (ETDEWEB)

    Azmy, Y.Y.; Buscaglia, G.C.; Zamonsky, O.M.

    1999-09-27

    This paper outlines some recent advances towards improving the accuracy of neutron calculations using the Arbitrarily High Order Transport-Nodal (AHOT-N) Method. These transport advances consist of several contributions: (a) A formula for the spatial weights that allows for the polynomial order to be raised arbitrarily high without suffering from pollution from round-off, error; (b) A reconstruction technique for the angular flux, based upon a recursive formula, that reduces the pointwise error by one order; (c) An a posterior error indicator that estimates the true error and its distribution throughout the domain, so that it can be used for adaptively reftig the approximation. Present results are mainly for ID, extension to 2D-3D is in progress.

  13. High-order harmonic generation from polar molecules

    DEFF Research Database (Denmark)

    Etches, Adam

    When a molecule is submitted to a very intense laser pulse it emits coherent bursts of light in each optical half-cycle of the laser field. This process is known as high-order harmonic generation because the spectrum consists of many peaks at energies corresponding to an integer amount of laser...... photons. The harmonics contain information about the wave function of the loosest bound electron on an Ångström length scale and attosecond time scale. However, accurate theoretical models are needed in order to extract this information. In this thesis the most widely used model of high-order harmonic...... generation is extended to polar molecules by including the laser-induced Stark shift of each molecular orbitals. The Stark shift is shown to have a major influence on the relative strength of harmonic bursts in neighbouring half-cycles, as well as leaving an imprint on the phase of the harmonics...

  14. Nanoporous polymer liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Christiansen, Mads Brøkner; Ndoni, Sokol

    2010-01-01

    We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.......We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented....

  15. International Conference on Spectral and High-Order Methods

    CERN Document Server

    Dumont, Ney; Hesthaven, Jan

    2017-01-01

    This book features a selection of high-quality papers chosen from the best presentations at the International Conference on Spectral and High-Order Methods (2016), offering an overview of the depth and breadth of the activities within this important research area. The carefully reviewed papers provide a snapshot of the state of the art, while the extensive bibliography helps initiate new research directions.

  16. A high order solver for the unbounded Poisson equation

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Rasmussen, Johannes Tophøj; Chatelain, Philippe

    2012-01-01

    This work improves upon Hockney and Eastwood's Fourier-based algorithm for the unbounded Poisson equation to formally achieve arbitrary high order of convergence without any additional computational cost. We assess the methodology on the kinematic relations between the velocity and vorticity fields....

  17. High-Order CESE Methods for Solving Hyperbolic PDEs (Preprint)

    Science.gov (United States)

    2011-05-03

    system of coupled hyperbolic PDE’s with arbitrarily high-order con- vergence . Numerical results show that the extended algorithm can achieve higher...Velocity- Stress Equations for Waves in Solids of Hexagonal Symmetry Solved by the Space-Time CESE Method. ASME Journal of Vibration and Acoustics, 133 (2

  18. High convergence order finite elements with lumped mass matrix

    DEFF Research Database (Denmark)

    Jensen, Morten skårup

    1996-01-01

    A method for deriving hexahedral finite elements with lumped mass matrices for three-dimensional problems is presented. These elements meet the theoretical conditions for high order convergence, and two numerical examples based on the three-dimensional scalar wave equation show that this is also...... the case in practice and that their accuracy is comparable to elements with consistent mass matrices....

  19. Production of organic nanoparticles by using nanoporous membranes

    Science.gov (United States)

    Tuz, A. A.; Şimşek, A. K.; Kazanci, M.

    2017-02-01

    In this research, organic nanoparticles are produced by using different nanoporous membranes with different diameters in different solutions. In production; two liquids, a feed solution and a receiver solution, are seperated by a nanoporous polycarbonate tracketched (PCTE) membrane. The feed solution is pumped through the membrane into the receiver solution. The feed solution contained biopolymers dissolved in HCl and the receiver solution contained NaOH. pH change is used as precipitation method. Chitosan, collagen and alginic acid sodium salt from brown algae are used as biomaterials in order to obtain nanoparticles. Different sized nanoporous membranes are used to find the ideal pore and particle sizes. Nanoparticles are illustrated by SEM and sphere-shaped nanoparticles with different diameters and needle shaped structures are observed.

  20. Benchmarking of de novo assembly algorithms for Nanopore data reveals optimal performance of OLC approaches.

    Science.gov (United States)

    Cherukuri, Yesesri; Janga, Sarath Chandra

    2016-08-22

    Improved DNA sequencing methods have transformed the field of genomics over the last decade. This has become possible due to the development of inexpensive short read sequencing technologies which have now resulted in three generations of sequencing platforms. More recently, a new fourth generation of Nanopore based single molecule sequencing technology, was developed based on MinION(®) sequencer which is portable, inexpensive and fast. It is capable of generating reads of length greater than 100 kb. Though it has many specific advantages, the two major limitations of the MinION reads are high error rates and the need for the development of downstream pipelines. The algorithms for error correction have already emerged, while development of pipelines is still at nascent stage. In this study, we benchmarked available assembler algorithms to find an appropriate framework that can efficiently assemble Nanopore sequenced reads. To address this, we employed genome-scale Nanopore sequenced datasets available for E. coli and yeast genomes respectively. In order to comprehensively evaluate multiple algorithmic frameworks, we included assemblers based on de Bruijn graphs (Velvet and ABySS), Overlap Layout Consensus (OLC) (Celera) and Greedy extension (SSAKE) approaches. We analyzed the quality, accuracy of the assemblies as well as the computational performance of each of the assemblers included in our benchmark. Our analysis unveiled that OLC-based algorithm, Celera, could generate a high quality assembly with ten times higher N50 & mean contig values as well as one-fifth the number of total number of contigs compared to other tools. Celera was also found to exhibit an average genome coverage of 12 % in E. coli dataset and 70 % in Yeast dataset as well as relatively lesser run times. In contrast, de Bruijn graph based assemblers Velvet and ABySS generated the assemblies of moderate quality, in less time when there is no limitation on the memory allocation, while greedy

  1. COMPARISON OF ADJUSTABLE HIGH-PHASE ORDER INDUCTION MOTORS’ MERITS

    Directory of Open Access Journals (Sweden)

    V.S. Petrushin

    2016-03-01

    Full Text Available Purpose. Development of mathematical models of adjustable electrical drives with high-phase order induction motors for their merits analysis at static and dynamical modes. Methodology. At the mathematical modeling main kinds of physical processes taking place in the high-phase order induction motors are considered: electromagnetic, electromechanical, energetic, thermal, mechanical, vibroacoustic ones. Besides, functional as well as mass, frame and value indicators of frequency converters are taking into account which permits to consider technical and economical aspects of the adjustable induction electrical drives. Creation of high-phase order induction motors’ modifications in possible on the base of a stock 3-phase motors of basic design. Polyphase supply of induction motors is guaranteed by a number of the adjustable electrical drives’ power circuits. Results. Modelling of a number of adjustable electrical drives with induction motors of different phase number working on the same load by its character, value and required adjustment range is carried out. At the utilization of the family of characteristics including mechanical ones at different adjustment parameters on which loading mechanism’s characteristics are superimposed regulation curves representing dependences of electrical, energetic, thermal, mechanical, vibroacoustic quantities on the motors’ number of revolutions are obtained. Originality. The proposed complex models of adjustable electrical drives with high-phase order induction motors give a possibility to carry out the grounded choice of the drive’s acceptable variant. Besides, they can be used as design models at the development of adjustable high-phase order induction motors. Practical value. The investigated change of vibroacoustic indicators at static and dynamical modes has been determined decrease of these indicators in the drives with number of phase exceeding 3.

  2. Accelerating experimental high-order spatial statistics calculations using GPUs

    Science.gov (United States)

    Li, Xue; Huang, Tao; Lu, De-Tang; Niu, Cong

    2014-09-01

    High-order spatial statistics have been widely used to describe the spatial phenomena in the field of geology science. Spatial statistics are subject to extremely heavy computational burden for large geostatistical models. To improve the computational efficiency, a parallel approach based on GPU (Graphics Processing Unit) is proposed for the calculation of high-order spatial statistics. The parallel scheme is achieved by utilizing a two-stage method to calculate the replicate of a moment for a given template simultaneously termed as the node-stage parallelism, and transform the spatial moments to cumulants for all lags of a template simultaneously termed as the template-stage parallelism. Also, a series of optimization strategies are proposed to take full advantage of the computational capabilities of GPUs, including the appropriate task allocation to the CUDA (Compute Unified Device Architecture) threads, proper organization of the GPU physical memory, and optimal improvement of the existed parallel routines. Tests are carried out on two training images to compare the performance of the GPU-based method with that of the serial implementation. Error analysis results indicate that the proposed parallel method can generate accurate cumulant maps, and the performance comparisons on various examples show that all the speedups for third-order, fourth-order and fifth-order cumulants calculation are over 17 times.

  3. High order accurate finite difference schemes based on symmetry preservation

    Science.gov (United States)

    Ozbenli, Ersin; Vedula, Prakash

    2017-11-01

    In this paper, we present a mathematical approach that is based on modified equations and the method of equivariant moving frames for construction of high order accurate invariant finite difference schemes that preserve Lie symmetry groups of underlying partial differential equations (PDEs). In the proposed approach, invariant (or symmetry preserving) numerical schemes with a desired (or fixed) order of accuracy are constructed from some non-invariant (base) numerical schemes. Modified forms of PDEs are used to improve the order of accuracy of existing schemes and these modified forms are obtained through addition of defect correction terms to the original forms of PDEs. These defect correction terms of modified PDEs that are noted from truncation error analysis are either completely removed from schemes or their representation is significantly simplified by considering convenient moving frames. This feature of the proposed method can especially be useful to avoid cumbersome numerical representations when high order schemes are developed from low order ones via the method of modified equations. The proposed method is demonstrated via construction of invariant numerical schemes with fixed (and higher) order of accuracy for some common linear and nonlinear problems (including the linear advection-diffusion equation in 1D and 2D, inviscid Burgers' equation, and viscous Burgers' equation) and the performance of these invariant numerical schemes is further evaluated. Our results indicate that such invariant numerical schemes obtained from existing base numerical schemes have the potential to significantly improve the quality of results not only in terms of desired higher order accuracy but also in the context of preservation of appropriate symmetry properties of underlying PDEs.

  4. Influence of adsorption thermodynamics on guest diffusivities in nanoporous crystalline materials

    NARCIS (Netherlands)

    Krishna, R.; van Baten, J.M.

    2013-01-01

    Published experimental data, underpinned by molecular simulations, are used to highlight the strong influence of adsorption thermodynamics on diffusivities of guest molecules inside ordered nanoporous crystalline materials such as zeolites, metal-organic frameworks (MOFs), and zeolitic imidazolate

  5. High-resolution microcontact printing and transfer of massive arrays of microorganisms on planar and compartmentalized nanoporous aluminium oxide

    NARCIS (Netherlands)

    Ingham, C.J.; Bomer, J.; Sprenkels, A.; Berg, van der A.; Vos, de W.M.; Hylckama, van J.

    2010-01-01

    Handling microorganisms in high throughput and their deployment into miniaturized platforms presents significant challenges. Contact printing can be used to create dense arrays of viable microorganisms. Such "living arrays", potentially with multiple identical replicates, are useful in the selection

  6. High-resolution microcontact printing and transfer of massive arrays of microorganisms on planar and compartmentalized nanoporous aluminium oxide

    NARCIS (Netherlands)

    Ingham, Colin; Bomer, Johan G.; Sprenkels, A.J.; van den Berg, Albert; Vos, Willem; van Hylckama Vlieg, Johan

    2010-01-01

    Handling microorganisms in high throughput and their deployment into miniaturized platforms presents significant challenges. Contact printing can be used to create dense arrays of viable microorganisms. Such "living arrays'', potentially with multiple identical replicates, are useful in the

  7. Development of high-order segmented MEMS deformable mirrors

    Science.gov (United States)

    Helmbrecht, Michael A.; He, Min; Kempf, Carl J.

    2012-03-01

    The areas of biological microscopy, ophthalmic research, and atmospheric turbulence correction require high-order DMs to obtain diffraction-limited images. Iris AO has been developing high-order MEMS DMs to address these requirements. Recent development has resulted in fully functional 489-actuator DMs capable of 9.5 µm stroke. For laser applications, the DMs were modified to make them compatible with high-reflectance dielectric coatings. Experimental results for the 489-actuator DMs with dielectric coatings shows they can be made with superb optical quality λ/93.3 rms (11.4 nm rms) and λ/75.9 rms (20.3 nm rms) for 1064 nm and 1540 nm coatings. Laser testing has demonstrated 300 W/cm2 power handling with off-the-shelf packaging. Power handling of 2800 W/cm2 is projected when incorporating packaging optimized for heat transfer.

  8. HOKF: High Order Kalman Filter for Epilepsy Forecasting Modeling.

    Science.gov (United States)

    Nguyen, Ngoc Anh Thi; Yang, Hyung-Jeong; Kim, Sunhee

    2017-08-01

    Epilepsy forecasting has been extensively studied using high-order time series obtained from scalp-recorded electroencephalography (EEG). An accurate seizure prediction system would not only help significantly improve patients' quality of life, but would also facilitate new therapeutic strategies to manage epilepsy. This paper thus proposes an improved Kalman Filter (KF) algorithm to mine seizure forecasts from neural activity by modeling three properties in the high-order EEG time series: noise, temporal smoothness, and tensor structure. The proposed High-Order Kalman Filter (HOKF) is an extension of the standard Kalman filter, for which higher-order modeling is limited. The efficient dynamic of HOKF system preserves the tensor structure of the observations and latent states. As such, the proposed method offers two main advantages: (i) effectiveness with HOKF results in hidden variables that capture major evolving trends suitable to predict neural activity, even in the presence of missing values; and (ii) scalability in that the wall clock time of the HOKF is linear with respect to the number of time-slices of the sequence. The HOKF algorithm is examined in terms of its effectiveness and scalability by conducting forecasting and scalability experiments with a real epilepsy EEG dataset. The results of the simulation demonstrate the superiority of the proposed method over the original Kalman Filter and other existing methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. On high-order perturbative calculations at finite density

    Energy Technology Data Exchange (ETDEWEB)

    Ghişoiu, Ioan, E-mail: ioan.ghisoiu@helsinki.fi [Helsinki Institute of Physics and Department of Physics, University of Helsinki (Finland); Gorda, Tyler, E-mail: tyler.gorda@helsinki.fi [Helsinki Institute of Physics and Department of Physics, University of Helsinki (Finland); Department of Physics, University of Colorado Boulder, Boulder, CO (United States); Kurkela, Aleksi, E-mail: aleksi.kurkela@cern.ch [Theoretical Physics Department, CERN, Geneva (Switzerland); Faculty of Science and Technology, University of Stavanger, Stavanger (Norway); Romatschke, Paul, E-mail: paul.romatschke@colorado.edu [Department of Physics, University of Colorado Boulder, Boulder, CO (United States); Center for Theory of Quantum Matter, University of Colorado, Boulder, CO (United States); Säppi, Matias, E-mail: matias.sappi@helsinki.fi [Helsinki Institute of Physics and Department of Physics, University of Helsinki (Finland); Vuorinen, Aleksi, E-mail: aleksi.vuorinen@helsinki.fi [Helsinki Institute of Physics and Department of Physics, University of Helsinki (Finland)

    2017-02-15

    We discuss the prospects of performing high-order perturbative calculations in systems characterized by a vanishing temperature but finite density. In particular, we show that the determination of generic Feynman integrals containing fermionic chemical potentials can be reduced to the evaluation of three-dimensional phase space integrals over vacuum on-shell amplitudes — a result reminiscent of a previously proposed “naive real-time formalism” for vacuum diagrams. Applications of these rules are discussed in the context of the thermodynamics of cold and dense QCD, where it is argued that they facilitate an extension of the Equation of State of cold quark matter to higher perturbative orders.

  10. Effect of Under-Resolved Grids on High Order Methods

    Science.gov (United States)

    Yee, H. C.; Sjoegreen, B.; Mansour, Nagi (Technical Monitor)

    2001-01-01

    There has been much discussion on verification and validation processes for establishing the credibility of CFD simulations. Since the early 1990s, many of the aeronautical and mechanical engineering related reference journals mandated that any accepted articles in numerical simulations (without known solutions to compared with) need to perform a minimum of one level of grid refinement and time step reduction. Due to the difficulty in analysis, the effect of under-resolved grids and the nonlinear behavior of available spatial discretizations, are scarcely discussed in the literature. Here, an under-resolved numerical simulation is one where the grid spacing being used is too coarse to resolve the smallest physically relevant scales of the chosen continuum governing equations that are of interest to the numerical modeler. With the advent of new developments in fourth-order or higher spatial schemes, it has become common to regard high order schemes as more accurate, reliable and require less grid points. The danger comes when one tries to perform computations with the coarsest grid possible while still hoping to maintain numerical results sufficiently accurate for complex flows, and especially, data-limited problems. On one hand, high order methods when applies to highly coupled multidimensional complex nonlinear problems might have different stability, convergence and reliability behavior than their well studied low order counterparts, especially for nonlinear schemes such as TVD, MUSCL with limiters, ENO, WENO and discrete Galerkin. On the other hand, high order methods involve more operation counts and systematic grid convergence study can be time consuming and prohibitively expansive. At the same time it is difficult to fully understand or categorize the different nonlinear behavior of finite discretizations, especially at the limits of under-resolution when different types of bifurcation phenomena might occur, depending on the combination of grid spacings, time

  11. DNA nanopore translocation in glutamate solutions

    NARCIS (Netherlands)

    Plesa, C.; Van Loo, N.; Dekker, C.

    2015-01-01

    Nanopore experiments have traditionally been carried out with chloride-based solutions. Here we introduce silver/silver-glutamate-based electrochemistry as an alternative, and study the viscosity, conductivity, and nanopore translocation characteristics of potassium-, sodium-, and lithium-glutamate

  12. High-resolution microcontact printing and transfer of massive arrays of microorganisms on planar and compartmentalized nanoporous aluminium oxide.

    Science.gov (United States)

    Ingham, Colin; Bomer, Johan; Sprenkels, Ad; van den Berg, Albert; de Vos, Willem; van Hylckama Vlieg, Johan

    2010-06-07

    Handling microorganisms in high throughput and their deployment into miniaturized platforms presents significant challenges. Contact printing can be used to create dense arrays of viable microorganisms. Such "living arrays", potentially with multiple identical replicates, are useful in the selection of improved industrial microorganisms, screening antimicrobials, clinical diagnostics, strain storage, and for research into microbial genetics. A high throughput method to print microorganisms at high density was devised, employing a microscope and a stamp with a massive array of PDMS pins. Viable bacteria (Lactobacillus plantarum, Esherichia coli), yeast (Candida albicans) and fungal spores (Aspergillus fumigatus) were deposited onto porous aluminium oxide (PAO) using arrays of pins with areas from 5 x 5 to 20 x 20 microm. Printing onto PAO with up to 8100 pins of 20 x 20 microm area with 3 replicates was achieved. Printing with up to 200 pins onto PAO culture chips (divided into 40 x 40 microm culture areas) allowed inoculation followed by effective segregation of microcolonies during outgrowth. Additionally, it was possible to print mixtures of C. albicans and spores of A. fumigatus with a degree of selectivity by capture onto a chemically modified PAO surface. High resolution printing of microorganisms within segregated compartments and on functionalized PAO surfaces has significant advantages over what is possible on semi-solid surfaces such as agar.

  13. Generation of high order geometry representations in Octree meshes

    Directory of Open Access Journals (Sweden)

    Harald G. Klimach

    2015-11-01

    Full Text Available We propose a robust method to convert triangulated surface data into polynomial volume data. Such polynomial representations are required for high-order partial differential solvers, as low-order surface representations would diminish the accuracy of their solution. Our proposed method deploys a first order spatial bisection algorithm to find robustly an approximation of given geometries. The resulting voxelization is then used to generate Legendre polynomials of arbitrary degree. By embedding the locally defined polynomials in cubical elements of a coarser mesh, this method can reliably approximate even complex structures, like porous media. It thereby is possible to provide appropriate material definitions for high order discontinuous Galerkin schemes. We describe the method to construct the polynomial and how it fits into the overall mesh generation. Our discussion includes numerical properties of the method and we show some results from applying it to various geometries. We have implemented the described method in our mesh generator Seeder, which is publically available under a permissive open-source license.

  14. High-order regularization in lattice-Boltzmann equations

    Science.gov (United States)

    Mattila, Keijo K.; Philippi, Paulo C.; Hegele, Luiz A.

    2017-04-01

    A lattice-Boltzmann equation (LBE) is the discrete counterpart of a continuous kinetic model. It can be derived using a Hermite polynomial expansion for the velocity distribution function. Since LBEs are characterized by discrete, finite representations of the microscopic velocity space, the expansion must be truncated and the appropriate order of truncation depends on the hydrodynamic problem under investigation. Here we consider a particular truncation where the non-equilibrium distribution is expanded on a par with the equilibrium distribution, except that the diffusive parts of high-order non-equilibrium moments are filtered, i.e., only the corresponding advective parts are retained after a given rank. The decomposition of moments into diffusive and advective parts is based directly on analytical relations between Hermite polynomial tensors. The resulting, refined regularization procedure leads to recurrence relations where high-order non-equilibrium moments are expressed in terms of low-order ones. The procedure is appealing in the sense that stability can be enhanced without local variation of transport parameters, like viscosity, or without tuning the simulation parameters based on embedded optimization steps. The improved stability properties are here demonstrated using the perturbed double periodic shear layer flow and the Sod shock tube problem as benchmark cases.

  15. Characterization of hydrophobic nanoporous particle liquids for energy absorption

    Science.gov (United States)

    Hsu, Yi; Liu, Yingtao

    2016-04-01

    Recently, the development of hydrophobic nanoporous technologies has drawn increased attention, especially for the applications of energy absorption and impact protection. Although significant amount of research has been conducted to synthesis and characterize materials to protect structures from impact damage, the tradition methods focused on converting kinetic energy to other forms, such as heat and cell buckling. Due to their high energy absorption efficiency, hydrophobic nanoporous particle liquids (NPLs) are one of the most attractive impact mitigation materials. During impact, such particles directly trap liquid molecules inside the non-wetting surface of nanopores in the particles. The captured impact energy is simply stored temporarily and isolated from the original energy transmission path. In this paper we will investigate the energy absorption efficiency of combinations of silica nanoporous particles and with multiple liquids. Inorganic particles, such as nanoporous silica, are characterized using scanning electron microscopy. Small molecule promoters, such as methanol and ethanol, are introduced to the prepared NPLs. Their effects on the energy absorption efficiency are studied in this paper. NPLs are prepared by dispersing the studied materials in deionized water. Energy absorption efficiency of these liquids are experimentally characterized using an Instron mechanical testing frame and in-house develop stainless steel hydraulic cylinder system.

  16. Diffusion, Surface Kinetics, and Detection in Solid-State Nanopores

    Science.gov (United States)

    Hoogerheide, David; Garaj, Slaven; Golovchenko, Jene

    2010-03-01

    Solid-state nanopores are promising sensors for single biomolecules. Most sensing applications rely on electronic detection of changes in the ionic transport through or across the nanopore in the 0.1--10 kHz frequency band. Our recent studies of the electronic noise properties of silicon nitride nanopores highlight both the suitability of nanopores for physical measurements and their limits of detection (PRL 102, 256804 (2009)). We explore the dependence of excess white noise, which is dominant at detection frequencies, on electrolyte concentration, temperature, and pH. We detect two distinct processes: number fluctuations and surface charge fluctuations. Number fluctuations arise from carrier diffusion through the nanopore and represent a fundamental limit of voltage-driven detection techniques. This sort of noise is minimized at high electrolyte concentrations in low viscosity solutions. In addition, the interaction of ions in the solution with the surface produces fluctuations in the surface charge, and hence the conductance. This noise varies strongly with pH. Both are masked by 1/f noise at low frequencies. The usefulness of these noise sources for measuring physical constants such as diffusivity and reaction kinetics will be discussed.

  17. Improving the Accuracy of High-Order Nodal Transport Methods

    Energy Technology Data Exchange (ETDEWEB)

    Azmy, Y.Y.; Buscaglia, G.C.; Zamonsky, O.M.

    1999-09-27

    This paper outlines some recent advances towards improving the accuracy of neutron transport calculations using the Arbitrarily High Order Transport-Nodal (AHOT-N) Method. These advances consist of several contributions: (a) A formula for the spatial weights that allows for the polynomial order to be raised arbitrarily high without suffering adverse effects from round-off error; (b) A reconstruction technique for the angular flux, based upon a recursive formula, that reduces the pointwise error by one ordeq (c) An a posterior error indicator that estimates the true error and its distribution throughout the domain, so that it can be used for adaptively refining the approximation. Present results are mainly for ID, extension to 2D-3D is in progress.

  18. High-order harmonic generation in laser plasma plumes

    CERN Document Server

    Ganeev, Rashid A

    2013-01-01

    This book represents the first comprehensive treatment of high-order harmonic generation in laser-produced plumes, covering the principles, past and present experimental status and important applications. It shows how this method of frequency conversion of laser radiation towards the extreme ultraviolet range matured over the course of multiple studies and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications. Significant discoveries and pioneering contributions of researchers in this field carried out in various laser scientific centers worldwide are included in this first attempt to describe the important findings in this area of nonlinear spectroscopy. "High-Order Harmonic Generation in Laser Plasma Plumes" is a self-contained and unified review of the most recent achievements in the field, such as the application of clusters (fullerenes, nanoparticles, nanotubes) for efficient harmonic generation of ultrashort laser pulses in cluster-containin...

  19. High-Order Modulation for Optical Fiber Transmission

    CERN Document Server

    Seimetz, Matthias

    2009-01-01

    Catering to the current interest in increasing the spectral efficiency of optical fiber networks by the deployment of high-order modulation formats, this monograph describes transmitters, receivers and performance of optical systems with high-order phase and quadrature amplitude modulation. In the first part of the book, the author discusses various transmitter implementation options as well as several receiver concepts based on direct and coherent detection, including designs of new structures. Hereby, both optical and electrical parts are considered, allowing the assessment of practicability and complexity. In the second part, a detailed characterization of optical fiber transmission systems is presented, regarding a wide range of modulation formats. It provides insight in the fundamental behavior of different formats with respect to relevant performance degradation effects and identifies the major trends in system performance.

  20. On high-order polynomial heat-balance integral implementations

    Directory of Open Access Journals (Sweden)

    Wood Alastair S.

    2009-01-01

    Full Text Available This article reconsiders aspects of the analysis conventionally used to establish accuracy, performance and limitations of the heat balance integral method: theoretical and practical rates of convergence are confirmed for a familiar piecewise heat-balance integral based upon mesh refinement, and the use of boundary conditions is discussed with respect to fixed and moving boundaries. Alternates to mesh refinement are increased order of approximation or non-polynomial approximants. Here a physically intuitive high-order polynomial heat balance integral formulation is described that exhibits high accuracy, rapid convergence, and desirable qualitative solution properties. The simple approach combines a global approximant of prescribed degree with spatial sub-division of the solution domain. As a variational-type method, it can be argued that heat-balance integral is simply 'one amongst many'. The approach is compared with several established variational formulations and performance is additionally assessed in terms of 'smoothness'.

  1. Full quantum trajectories resolved high-order harmonic generation.

    Science.gov (United States)

    Ye, Peng; He, Xinkui; Teng, Hao; Zhan, Minjie; Zhong, Shiyang; Zhang, Wei; Wang, Lifeng; Wei, Zhiyi

    2014-08-15

    We use a carrier-envelope-phase stabilized sub-2-cycle laser pulse to generate high-order harmonics and study how the two-dimensional spectrum of harmonics, with the resolutions in temporal frequency and spatial frequency, is shaped by the laser phase. An arrowlike spectrum obtained experimentally when the gas cell is located in front of the laser focus point shows a resolution of full quantum trajectories; i.e., harmonics from different trajectories stand on different positions in this spectrum. In particular, due to the laser phase combined with the classical-like action, the harmonics from short and long trajectories differ maximally in their curvatures of wave fronts in the generation area, and so occupy very different ranges of spatial frequency at the far field. The result directly gives a full map of quantum trajectories in high-order harmonic generation. The conclusion is supported by an analytical model and quantum mechanics simulations.

  2. A High-Order CFS Algorithm for Clustering Big Data

    OpenAIRE

    Fanyu Bu; Zhikui Chen; Peng Li; Tong Tang; Ying Zhang

    2016-01-01

    With the development of Internet of Everything such as Internet of Things, Internet of People, and Industrial Internet, big data is being generated. Clustering is a widely used technique for big data analytics and mining. However, most of current algorithms are not effective to cluster heterogeneous data which is prevalent in big data. In this paper, we propose a high-order CFS algorithm (HOCFS) to cluster heterogeneous data by combining the CFS clustering algorithm and the dropout deep learn...

  3. Discrete nonlinear Schrodinger equations with arbitrarily high-order nonlinearities

    DEFF Research Database (Denmark)

    Khare, A.; Rasmussen, Kim Ø; Salerno, M.

    2006-01-01

    A class of discrete nonlinear Schrodinger equations with arbitrarily high-order nonlinearities is introduced. These equations are derived from the same Hamiltonian using different Poisson brackets and include as particular cases the saturable discrete nonlinear Schrodinger equation and the Ablowitz......-Ladik equation. As a common property, these equations possess three kinds of exact analytical stationary solutions for which the Peierls-Nabarro barrier is zero. Several properties of these solutions, including stability, discrete breathers, and moving solutions, are investigated....

  4. High order numerical methods for myxobacteria pattern formation

    OpenAIRE

    Glavan, Ana Maria

    2015-01-01

    Rippling patterns of myxobacteria appear in starving colonies before they aggregate to form fruiting bodies. These periodic traveling cell density waves arise from the coordination of individual cell reversals, resulting from an internal clock regulating them, and from contact signaling during bacterial collisions. Our main interest in this research is the numerical approximation with high order accuracy in space of the solutions of mathematical models proposed for myxobacteria rippling. We r...

  5. High-order harmonic generation via multicolor beam superposition

    Science.gov (United States)

    Sarikhani, S.; Batebi, S.

    2017-09-01

    In this article, femtosecond pulses, especially designed by multicolor beam superposition are used for high-order harmonic generation. To achieve this purpose, the spectral difference between the beams, and their width are taken to be small values, i.e., less than 1 nm. Applying a Gaussian distribution to the beam intensities leads to a more distinct pulses. Also, it is seen that these pulses have an intrinsic linear chirp. By changing the width of the Gaussian distributions, we can have several pulses with different bandwidths and hence various pulse duration. Thus, the study of these broadband pulse influences, in contrast with monochromatic pulses, on the atomic or molecular targets was achievable. So, we studied numerically the effect of these femtosecond pulses on behavior of the high-order harmonics generated after interaction between the pulse and the atomic hydrogen. For this study, we adjusted the beam intensities so that the produced pulse intensity be in the over-barrier ionization region. This makes the power spectrum of high-order harmonics more extensive. Cutoff frequency of the power spectrum along with the first harmonic intensity and its shift from the incident pulse are investigated. Additionally, maximum ionization probability with respect to the pulse bandwidth was also studied.

  6. High-order harmonic generation in laser plasma: Recent achievements

    Science.gov (United States)

    Ganeev, R. A.

    2012-07-01

    Recent studies of high-order harmonic generation of laser radiation in laser-produced plasma show new attractive developments in this field. Those include generation of extended harmonics in plasma plumes, new approaches in application of two-color pump, generation of extremely broadened harmonics, further developments in harmonic generation in clusters (fullerenes, carbon nanotubes, in-situ produced nanoparticles), destructive interference of harmonics from different emitters, resonance-induced enhancement of harmonics, applications of high pulse repetition rate lasers for the enhancement of average power of generating harmonics, observation of quantum path signatures, etc. We review some of these recent developments.

  7. Spatial Mode Control of High-Order Harmonics

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, I.; Mevel, E.; Zerne, R.; LHuillier, A.; Antoine, P.; Wahlstroem, C. [Department of Physics, Lund Institute of Technology, S-221 00 Lund (Sweden)]|[Commissariat a l`Energie Atomique, DSM/DRECAM/SPAM, Centre d`Etudes de Saclay, 91191 Gif-sur-Yvette (France)

    1996-08-01

    We demonstrate that the spatial mode of high-order harmonics can be continuously controlled. The control is achieved by spatially modulating the degree of elliptical polarization of the fundamental field using birefringent optics. A highly sensitive relationship between the efficiency of harmonic generation and the degree of laser elliptical polarization leads to atoms emitting harmonics only in regions of linear polarization. The harmonics are emitted as annular beams whose angles of divergence can be continuously varied. {copyright} {ital 1996 The American Physical Society.}

  8. Gyroid nanoporous scaffold for conductive polymers

    DEFF Research Database (Denmark)

    Guo, Fengxiao; Schulte, Lars; Zhang, Weimin

    2011-01-01

    Conductive nanoporous polymers with interconnected large surface area have been prepared by depositing polypyrrole onto nanocavity walls of nanoporous 1,2-polybutadiene films with gyroid morphology. Vapor phase polymerization of pyrrole was used to generate ultrathin films and prevent pore blocking....... The resulting nanoporous polymers exhibited a promising electroactivity....

  9. Boosting infrared energy transfer in 3D nanoporous gold antennas.

    Science.gov (United States)

    Garoli, D; Calandrini, E; Bozzola, A; Ortolani, M; Cattarin, S; Barison, S; Toma, A; De Angelis, F

    2017-01-05

    The applications of plasmonics to energy transfer from free-space radiation to molecules are currently limited to the visible region of the electromagnetic spectrum due to the intrinsic optical properties of bulk noble metals that support strong electromagnetic field confinement only close to their plasma frequency in the visible/ultraviolet range. In this work, we show that nanoporous gold can be exploited as a plasmonic material for the mid-infrared region to obtain strong electromagnetic field confinement, co-localized with target molecules into the nanopores and resonant with their vibrational frequency. The effective optical response of the nanoporous metal enables the penetration of optical fields deep into the nanopores, where molecules can be loaded thus achieving a more efficient light-matter coupling if compared to bulk gold. In order to realize plasmonic resonators made of nanoporous gold, we develop a nanofabrication method based on polymeric templates for metal deposition and we obtain antenna arrays resonating at mid-infrared wavelengths selected by design. We then coat the antennas with a thin (3 nm) silica layer acting as the target dielectric layer for optical energy transfer. We study the strength of the light-matter coupling at the vibrational absorption frequency of silica at 1240 cm-1 through the analysis of the experimental Fano lineshape that is benchmarked against identical structures made of bulk gold. The boost in the optical energy transfer from free-space mid-infrared radiation to molecular vibrations in nanoporous 3D nanoantenna arrays can open new application routes for plasmon-enhanced physical-chemical reactions.

  10. Integrated high-order surface diffraction gratings for diode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Zolotarev, V V; Leshko, A Yu; Pikhtin, N A; Slipchenko, S O; Sokolova, Z N; Lubyanskiy, Ya V; Voronkova, N V; Tarasov, I S [Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2015-12-31

    High-order surface diffraction gratings acting as a distributed Bragg reflector (DBR) in mesa stripe semiconductor lasers (λ = 1030 nm) have been studied theoretically and experimentally. Higher order interfering radiation modes (IRMs), which propagate off the plane of the waveguide, have been shown to have a crucial effect on the reflection and transmission spectra of the DBR. The decrease in the reflectivity of the DBR in response to the increase in the diffraction efficiency of these modes may reach 80% and more. According to theoretical analysis results, the intensity of the higher order IRMs is determined by the geometry of the DBR groove profile. Experimental data demonstrate that the noncavity modes are responsible for parasitic light leakage losses in the laser cavity. It has been shown that, in the case of nonoptimal geometry of the grating groove profile, the overall external differential quantum efficiency of the parasitic laser emission may exceed 45%, which is more than half of the laser output power. The optimal geometry of the DBR groove profile is trapezoidal, with the smallest possible lower base. Experimental evidence has been presented that this geometry considerably reduces the power of the higher order IRMs and minimises the parasitic light leakage loss. (lasers)

  11. Rad-Hydro with a High-Order, Low-Order Method

    Energy Technology Data Exchange (ETDEWEB)

    Wollaber, Allan Benton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Park, HyeongKae [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lowrie, Robert Byron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rauenzahn, Rick M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cleveland, Mathew Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-04

    Moment-based acceleration via the development of “high-order, low-order” (HO-LO) algorithms has provided substantial accuracy and efficiency enhancements for solutions of the nonlinear, thermal radiative transfer equations by CCS-2 and T-3 staff members. Accuracy enhancements over traditional, linearized methods are obtained by solving a nonlinear, timeimplicit HO-LO system via a Jacobian-free Newton Krylov procedure. This also prevents the appearance of non-physical maximum principle violations (“temperature spikes”) associated with linearization. Efficiency enhancements are obtained in part by removing “effective scattering” from the linearized system. In this highlight, we summarize recent work in which we formally extended the HO-LO radiation algorithm to include operator-split radiation-hydrodynamics.

  12. Efficient high-order suppression system for a metrology beamline.

    Science.gov (United States)

    Sokolov, A; Sertsu, M G; Gaupp, A; Lüttecke, M; Schäfers, F

    2018-01-01

    High-quality metrology with synchrotron radiation requires in particular a very high spectral purity of the incident beam. This is usually achieved by a set of transmission filters with suitable absorption edges to suppress high-order radiation of the monochromator. The at-wavelength metrology station at a BESSY-II bending-magnet collimated plane-grating monochromator (c-PGM) beamline has recently commissioned a high-order suppression system (HiOS) based on four reflections from mirrors which can be inserted into the beam path. Two pairs of mirrors are aligned parallel so as not to disturb the original beam path and are rotated clockwise and counter-clockwise. Three sets of coatings are available for the different energy ranges and the incidence angle is freely tunable to find the optimum figure of merit for maximum suppression at maximum transmission for each photon energy required. Measured performance results of the HiOS for the EUV and XUV range are compared with simulations, and applications are discussed.

  13. Cluster size dependence of high-order harmonic generation

    CERN Document Server

    Tao, Y; Bastiaens, H M J; van der Slot, P J M; Biedron, S G; Milton, S V; Boller, K -J

    2016-01-01

    We investigate high-order harmonic generation (HHG) from noble gas clusters in a supersonic gas jet. To identify the contribution of harmonic generation from clusters versus that from gas monomers, we measure the high-order harmonic output over a broad range of the total atomic number density in the jet (from 3x10^{16} cm^{-3} to 3x10^{18} cm^{-3}) at two different reservoir temperatures (303 K and 363 K). For the first time in the evaluation of the harmonic yield in such measurements, the variation of the liquid mass fraction, g, versus pressure and temperature is taken into consideration, which we determine, reliably and consistently, to be below 20% within our range of experimental parameters. Based on measurements with a thin jet where significant variations in reabsorption and the phase matching conditions can be neglected, we conclude that atoms in the form of small clusters (average cluster size < 1000 atoms) provide the same higher-order nonlinear response as single-atoms. This implies that HHG in ...

  14. Surface hydration drives rapid water imbibition into strongly hydrophilic nanopores.

    Science.gov (United States)

    Fang, Chao; Qiao, Rui

    2017-08-09

    The imbibition of liquids into nanopores plays a critical role in numerous applications, and most prior studies focused on imbibition due to capillary flows. Here we report molecular simulations of the imbibition of water into single mica nanopores filled with pressurized gas. We show that, while capillary flow is suppressed by the high gas pressure, water is imbibed into the nanopore through surface hydration in the form of monolayer liquid films. As the imbibition front moves, the water film behind it gradually densifies. Interestingly, the propagation of the imbibition front follows a simple diffusive scaling law. The effective diffusion coefficient of the imbibition front, however, is more than ten times larger than the diffusion coefficient of the water molecules in the water film adsorbed on the pore walls. We clarify the mechanism for the rapid water imbibition observed here.

  15. Nanoporous Carbon Monoliths with Tunable Thermal Insulation and Mechanical Properties.

    Science.gov (United States)

    Wang, Xiaopeng; Chen, Fenghua; Luo, Zhenhua; Li, Hao; Zhao, Tong

    2016-01-01

    In this work, nanoscale porous carbon monoliths, with excellent compressive strength and thermal insulation, were obtained with a simple method of carbonizing cured phenol-formaldehyde resin/poly(methyl methacrylate) blends. Apparent density, pore size and morphology of the carbon monoliths were tailored by changing the composition, curing process and carbonization temperature. The continuous nanopores played a key role in enhancing mechanical and thermal performance of the carbon materials. When PMMA concentration was 25%, apparent density and thermal conductivity of the nanoporous carbonaceous monoliths were obtained as low as 1.07 g · cm⁻³ and 0.42 W/(m · K), decreasing by 29.4% and 35.4% than that of carbonaceous monoliths obtained from pure PF; while compressive strength of the nanoporous carbonaceous monoliths was as high as 34 MPa, which was improved over five times than that of pure PF carbon monoliths.

  16. High-order total variation minimization for interior SPECT

    Science.gov (United States)

    Yang, Jiansheng; Yu, Hengyong; Jiang, Ming; Wang, Ge

    2011-01-01

    Recently, we developed an approach for solving the computed tomography (CT) interior problem based on the high-order TV (HOT) minimization, assuming that a region-of-interest (ROI) is piecewise polynomial. In this paper, we generalize this finding from the CT field to the single-photon emission computed tomography (SPECT) field, and prove that if an ROI is piecewise polynomial, then the ROI can be uniquely reconstructed from the SPECT projection data associated with the ROI through the HOT minimization. Also, we propose a new formulation of HOT, which has an explicit formula for any n-order piecewise polynomial function, while the original formulation has no explicit formula for n ≥ 2. Finally, we verify our theoretical results in numerical simulation, and discuss relevant issues. PMID:22215932

  17. A high-order SPH method by introducing inverse kernels

    Directory of Open Access Journals (Sweden)

    Le Fang

    2017-02-01

    Full Text Available The smoothed particle hydrodynamics (SPH method is usually expected to be an efficient numerical tool for calculating the fluid-structure interactions in compressors; however, an endogenetic restriction is the problem of low-order consistency. A high-order SPH method by introducing inverse kernels, which is quite easy to be implemented but efficient, is proposed for solving this restriction. The basic inverse method and the special treatment near boundary are introduced with also the discussion of the combination of the Least-Square (LS and Moving-Least-Square (MLS methods. Then detailed analysis in spectral space is presented for people to better understand this method. Finally we show three test examples to verify the method behavior.

  18. Nanoporous polymers for hydrogen storage.

    Science.gov (United States)

    Germain, Jonathan; Fréchet, Jean M J; Svec, Frantisek

    2009-05-01

    The design of hydrogen storage materials is one of the principal challenges that must be met before the development of a hydrogen economy. While hydrogen has a large specific energy, its volumetric energy density is so low as to require development of materials that can store and release it when needed. While much of the research on hydrogen storage focuses on metal hydrides, these materials are currently limited by slow kinetics and energy inefficiency. Nanostructured materials with high surface areas are actively being developed as another option. These materials avoid some of the kinetic and thermodynamic drawbacks of metal hydrides and other reactive methods of storing hydrogen. In this work, progress towards hydrogen storage with nanoporous materials in general and porous organic polymers in particular is critically reviewed. Mechanisms of formation for crosslinked polymers, hypercrosslinked polymers, polymers of intrinsic microporosity, and covalent organic frameworks are discussed. Strategies for controlling hydrogen storage capacity and adsorption enthalpy via manipulation of surface area, pore size, and pore volume are discussed in detail.

  19. Plasma high-order-harmonic generation from ultraintense laser pulses

    Science.gov (United States)

    Tang, Suo; Kumar, Naveen; Keitel, Christoph H.

    2017-05-01

    Plasma high-order-harmonic generation from an extremely intense short-pulse laser is explored by including the effects of ion motion, electron-ion collisions, and radiation reaction force in the plasma dynamics. The laser radiation pressure induces plasma ion motion through the hole-boring effect, resulting in frequency shifting and widening of the harmonic spectra. The classical radiation reaction force slightly mitigates the frequency broadening caused by the ion motion. Based on the results and physical considerations, parameter maps highlighting the optimum regions for generating a single intense attosecond pulse and coherent XUV radiation are presented.

  20. High-order harmonic generation in a capillary discharge

    Science.gov (United States)

    Rocca, Jorge J.; Kapteyn, Henry C.; Mumane, Margaret M.; Gaudiosi, David; Grisham, Michael E.; Popmintchev, Tenio V.; Reagan, Brendan A.

    2010-06-01

    A pre-ionized medium created by a capillary discharge results in more efficient use of laser energy in high-order harmonic generation (HHG) from ions. It extends the cutoff photon energy, and reduces the distortion of the laser pulse as it propagates down the waveguide. The observed enhancements result from a combination of reduced ionization energy loss and reduced ionization-induced defocusing of the driving laser as well as waveguiding of the driving laser pulse. The discharge plasma also provides a means to spectrally tune the harmonics by tailoring the initial level of ionization of the medium.

  1. Stability of the high-order finite elements for acoustic or elastic wave propagation with high-order time stepping

    KAUST Repository

    De Basabe, Jonás D.

    2010-04-01

    We investigate the stability of some high-order finite element methods, namely the spectral element method and the interior-penalty discontinuous Galerkin method (IP-DGM), for acoustic or elastic wave propagation that have become increasingly popular in the recent past. We consider the Lax-Wendroff method (LWM) for time stepping and show that it allows for a larger time step than the classical leap-frog finite difference method, with higher-order accuracy. In particular the fourth-order LWM allows for a time step 73 per cent larger than that of the leap-frog method; the computational cost is approximately double per time step, but the larger time step partially compensates for this additional cost. Necessary, but not sufficient, stability conditions are given for the mentioned methods for orders up to 10 in space and time. The stability conditions for IP-DGM are approximately 20 and 60 per cent more restrictive than those for SEM in the acoustic and elastic cases, respectively. © 2010 The Authors Journal compilation © 2010 RAS.

  2. Design and high order optimization of the ATF2 lattices

    CERN Document Server

    Marin, E; Woodley, M; Kubo, K; Okugi, T; Tauchi, T; Urakawa, J; Tomas, R

    2013-01-01

    The next generation of future linear colliders (LC) demands nano-meter beam sizes at the interaction point (IP) in order to reach the required luminosity. The final focus system (FFS) of a LC is meant to deliver such small beam sizes. The Accelerator Test Facility (ATF) aims to test the feasibility of the new local chromaticity correction scheme which the future LCs are based on. To this end the ATF2 nominal and ultra-low beta* lattices are design to vertically focus the beam at the IP to 37nm and 23nm, respectively if error-free lattices are considered. However simulations show that the measured field errors of the ATF2 magnets preclude to reach the mentioned spot sizes. This paper describes the optimization of high order aberrations of the ATF2 lattices in order to minimize the detrimental effect of the measured multipole components for both ATF2 lattices. Specifically three solutions are studied, the replacement of the last focusing quadrupole (QF1FF), insertion of octupole magnets and optics modification....

  3. DNA Motion Induced by Electrokinetic Flow near an Au Coated Nanopore Surface as Voltage Controlled Gate

    Science.gov (United States)

    Sugimoto, Manabu; Kato, Yuta; Ishida, Kentaro; Hyun, Changbae; Li, Jiali

    2014-01-01

    The diffusion and drift motion of λ DNA molecules on Au coated membrane surface near nanopores prior to their translocation through solid-state nanopores are investigated using fluorescence microscopy. With the capability of controlling electric potential at the Au surface as a gate voltage, Vgate, the motions of DNA molecules vary dramatically near the nanopores in our observations, presumably generated by electrokinetic flow. We carefully investigate theses DNA motions with different values of Vgate in order to alter the densities and polarities of counterions; which are expected to change the flow speed or direction, respectively. Depending on Vgate, our observations have revealed the critical distance from a nanopore for DNA molecules to be attracted or to be repelled, DNA’s anisotropic and unsteady drifting motions and accumulations of DNA molecules near the nanopore entrance. Further finite element method (FEM) numerical simulations indicate that the electrokinetic flow could explain these unusual DNA motions near metal collated gated nanopores qualitatively. Finally, we demonstrate the possibility to control the speed and direction of DNA motion near or through a nanopore, for example, recapturing a single DNA molecule multiple times with AC voltages on the Vgate. PMID:25611963

  4. Optimal explicit strong stability preserving Runge–Kutta methods with high linear order and optimal nonlinear order

    KAUST Repository

    Gottlieb, Sigal

    2015-04-10

    High order spatial discretizations with monotonicity properties are often desirable for the solution of hyperbolic PDEs. These methods can advantageously be coupled with high order strong stability preserving time discretizations. The search for high order strong stability time-stepping methods with large allowable strong stability coefficient has been an active area of research over the last two decades. This research has shown that explicit SSP Runge-Kutta methods exist only up to fourth order. However, if we restrict ourselves to solving only linear autonomous problems, the order conditions simplify and this order barrier is lifted: explicit SSP Runge-Kutta methods of any linear order exist. These methods reduce to second order when applied to nonlinear problems. In the current work we aim to find explicit SSP Runge-Kutta methods with large allowable time-step, that feature high linear order and simultaneously have the optimal fourth order nonlinear order. These methods have strong stability coefficients that approach those of the linear methods as the number of stages and the linear order is increased. This work shows that when a high linear order method is desired, it may still be worthwhile to use methods with higher nonlinear order.

  5. XAO coronagraphy with the High-Order Test bench

    Directory of Open Access Journals (Sweden)

    Kasper M.

    2011-07-01

    Full Text Available Extreme adaptive optics systems dedicated to the search for extra solar planets are currently being developed for 8–10 meter class telescopes. The High-Order Test bench (HOT is a high-contrast imaging adaptive optics bench developed at ESO. Its objective is to test and optimize different techniques and technologies (e.g. wave front sensors, coronagraphs, speckle calibration methods…. It mimics realistic conditions at a telescope (e.g. VLT, including turbulence generator, XAO, and various near-IR coronagraphs. Here we provide a short overview of the system, and present results of recent AO-closed loop coronagraphic runs obtained with an Apodized Pupil Lyot Coronagraph (APLC.

  6. A High-Order CFS Algorithm for Clustering Big Data

    Directory of Open Access Journals (Sweden)

    Fanyu Bu

    2016-01-01

    Full Text Available With the development of Internet of Everything such as Internet of Things, Internet of People, and Industrial Internet, big data is being generated. Clustering is a widely used technique for big data analytics and mining. However, most of current algorithms are not effective to cluster heterogeneous data which is prevalent in big data. In this paper, we propose a high-order CFS algorithm (HOCFS to cluster heterogeneous data by combining the CFS clustering algorithm and the dropout deep learning model, whose functionality rests on three pillars: (i an adaptive dropout deep learning model to learn features from each type of data, (ii a feature tensor model to capture the correlations of heterogeneous data, and (iii a tensor distance-based high-order CFS algorithm to cluster heterogeneous data. Furthermore, we verify our proposed algorithm on different datasets, by comparison with other two clustering schemes, that is, HOPCM and CFS. Results confirm the effectiveness of the proposed algorithm in clustering heterogeneous data.

  7. High-order finite element methods for cardiac monodomain simulations

    Directory of Open Access Journals (Sweden)

    Kevin P Vincent

    2015-08-01

    Full Text Available Computational modeling of tissue-scale cardiac electrophysiology requires numerically converged solutions to avoid spurious artifacts. The steep gradients inherent to cardiac action potential propagation necessitate fine spatial scales and therefore a substantial computational burden. The use of high-order interpolation methods has previously been proposed for these simulations due to their theoretical convergence advantage. In this study, we compare the convergence behavior of linear Lagrange, cubic Hermite, and the newly proposed cubic Hermite-style serendipity interpolation methods for finite element simulations of the cardiac monodomain equation. The high-order methods reach converged solutions with fewer degrees of freedom and longer element edge lengths than traditional linear elements. Additionally, we propose a dimensionless number, the cell Thiele modulus, as a more useful metric for determining solution convergence than element size alone. Finally, we use the cell Thiele modulus to examine convergence criteria for obtaining clinically useful activation patterns for applications such as patient-specific modeling where the total activation time is known a priori.

  8. High-order finite element methods for cardiac monodomain simulations

    Science.gov (United States)

    Vincent, Kevin P.; Gonzales, Matthew J.; Gillette, Andrew K.; Villongco, Christopher T.; Pezzuto, Simone; Omens, Jeffrey H.; Holst, Michael J.; McCulloch, Andrew D.

    2015-01-01

    Computational modeling of tissue-scale cardiac electrophysiology requires numerically converged solutions to avoid spurious artifacts. The steep gradients inherent to cardiac action potential propagation necessitate fine spatial scales and therefore a substantial computational burden. The use of high-order interpolation methods has previously been proposed for these simulations due to their theoretical convergence advantage. In this study, we compare the convergence behavior of linear Lagrange, cubic Hermite, and the newly proposed cubic Hermite-style serendipity interpolation methods for finite element simulations of the cardiac monodomain equation. The high-order methods reach converged solutions with fewer degrees of freedom and longer element edge lengths than traditional linear elements. Additionally, we propose a dimensionless number, the cell Thiele modulus, as a more useful metric for determining solution convergence than element size alone. Finally, we use the cell Thiele modulus to examine convergence criteria for obtaining clinically useful activation patterns for applications such as patient-specific modeling where the total activation time is known a priori. PMID:26300783

  9. Ion and water transport in charge-modified graphene nanopores

    Science.gov (United States)

    Qiu, Ying-Hua; Li, Kun; Chen, Wei-Yu; Si, Wei; Tan, Qi-Yan; Chen, Yun-Fei

    2015-10-01

    Porous graphene has a high mechanical strength and an atomic-layer thickness that makes it a promising material for material separation and biomolecule sensing. Electrostatic interactions between charges in aqueous solutions are a type of strong long-range interaction that may greatly influence fluid transport through nanopores. In this study, molecular dynamic simulations were conducted to investigate ion and water transport through 1.05-nm diameter monolayer graphene nanopores, with their edges charge-modified. Our results indicated that these nanopores are selective to counterions when they are charged. As the charge amount increases, the total ionic currents show an increase-decrease profile while the co-ion currents monotonically decrease. The co-ion rejection can reach 76.5% and 90.2% when the nanopores are negatively and positively charged, respectively. The Cl- ion current increases and reaches a plateau, and the Na+ current decreases as the charge amount increases in systems in which Na+ ions act as counterions. In addition, charge modification can enhance water transport through nanopores. This is mainly due to the ion selectivity of the nanopores. Notably, positive charges on the pore edges facilitate water transport much more strongly than negative charges. Project supported by the National Basic Research Program of China (Grant Nos. 2011CB707601 and 2011CB707605), the National Natural Science Foundation of China (Grant No. 50925519), the Fundamental Research Funds for the Central Universities, Funding of Jiangsu Provincial Innovation Program for Graduate Education, China (Grant No. CXZZ13_0087), and the Scientific Research Foundation of Graduate School of Southeast University (Grant No. YBJJ 1322).

  10. A triaxial tensile deformation-induced nanoporous structure of aluminium: estimation of surface area, solid volume, and dimensionless aspect ratio.

    Science.gov (United States)

    Kumar, Sunil; Das, Suchandan K

    2017-08-09

    Nanoporous aluminium has great importance for large scale production of automobile and aerospace spare parts due to its lightweight and non-corrosive nature. It is also suitable for various packaging applications of edible things, electronic components, and medicines. We have used triaxial tensile deformation methodology to create a nanoporous structure of aluminium using molecular dynamics simulation. The surface area and solid volume have been calculated to characterize the 3-D nanoporous structure of aluminium. We have quantitatively characterized the growth and coalescences of the nanoporous structure via estimation of the number of nanopores, nanopore diameters, and dimensionless aspect-ratios (surface area to volume ratio). A high aspect ratio indicates a large number of tiny nanopores in the 3-D nanoporous structure of aluminium. We have found that crystalline aluminium (under ambient condition) significantly depicts a smaller aspect ratio as compared to amorphous aluminium during triaxial tensile deformation. We believe that the results of this study will provide new understanding to the researchers for the design and characterization of nanoporous metals.

  11. Magnetic nanoporous carbon as an adsorbent for the extraction of phthalate esters in environmental water and aloe juice samples.

    Science.gov (United States)

    Liu, Li; Hao, Yunhui; Ren, Yiqian; Wang, Chun; Wu, Qiuhua; Wang, Zhi

    2015-05-01

    In this work, magnetic nanoporous carbon with high surface area and ordered structure was synthesized using cheap commercial silica gel as template and sucrose as the carbon source. The prepared magnetic nanoporous carbon was firstly used as an adsorbent for the extraction of phthalate esters, including diethyl phthalate, diallyl phthalate, and di-n-propyl-phthalate, from lake water and aloe juice samples. Several parameters that could affect the extraction efficiency were optimized. Under the optimum conditions, the limit of detection of the method (S/N = 3) was 0.10 ng/mL for water sample and 0.20 ng/mL for aloe juice sample. The linearity was observed over the concentration range of 0.50-150.0 and 1.0-200.0 ng/mL for water and aloe juice samples, respectively. The results showed that the magnetic nanoporous carbon has a high adsorptive capability toward the target phthalate esters in water and aloe juice samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Basic evaluation of typical nanoporous silica nanoparticles in being drug carrier: Structure, wettability and hemolysis.

    Science.gov (United States)

    Li, Jing; Guo, Yingyu

    2017-04-01

    Herein, the present work devoted to study the basic capacity of nanoporous silica nanoparticles in being drug carrier that covered structure, wettability and hemolysis so as to provide crucial evaluation. Typical nanoporous silica nanoparticles that consist of nanoporous silica nanoparticles (NSN), amino modified nanoporous silica nanoparticles (amino-NSN), carboxyl modified nanoporous silica nanoparticles (carboxyl-NSN) and hierachical nanoporous silica nanoparticles (hierachical-NSN) were studied. The results showed that their wettability and hemolysis were closely related to structure and surface modification. Basically, wettability became stronger as the amount of OH on the surface of NSN was higher. Both large nanopores and surface modification can reduce the wettability of NSN. Furthermore, NSN series were safe to be used when they circulated into the blood in low concentration, while if high concentration can not be avoided during administration, high porosity or amino modification of NSN were safer to be considered. It is believed that the basic evaluation of NSN can make contribution in providing scientific instruction for designing drug loaded NSN systems. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Thermal effects of water intrusion in hydrophobic nanoporous materials.

    Science.gov (United States)

    Karbowiak, Thomas; Paulin, Christian; Ballandras, Anthony; Weber, Guy; Bellat, Jean-Pierre

    2009-07-29

    Liquid water intrusion in hydrophobic nanoporous silicalite-1, a pure siliceous zeolite, in isothermal conditions under high pressure produces an endothermic effect. After intrusion, confined water in zeolite pores is in a different state from that of the liquid bulk water. Such forced intrusion also chemically modifies the material and tends to render it slightly more hydrophilic.

  14. Nanoporous Glasses for Nuclear Waste Containment

    Directory of Open Access Journals (Sweden)

    Thierry Woignier

    2016-01-01

    Full Text Available Research is in progress to incorporate nuclear waste in new matrices with high structural stability, resistance to thermal shock, and high chemical durability. Interactions with water are important for materials used as a containment matrix for the radio nuclides. It is indispensable to improve their chemical durability to limit the possible release of radioactive chemical species, if the glass structure is attacked by corrosion. By associating high structural stability and high chemical durability, silica glass optimizes the properties of a suitable host matrix. According to an easy sintering stage, nanoporous glasses such as xerogels, aerogels, and composite gels are alternative ways to synthesize silica glass at relatively low temperatures (≈1,000–1,200°C. Nuclear wastes exist as aqueous salt solutions and we propose using the open pore structure of the nanoporous glass to enable migration of the solution throughout the solid volume. The loaded material is then sintered, thereby trapping the radioactive chemical species. The structure of the sintered materials (glass ceramics is that of nanocomposites: actinide phases (~100 nm embedded in a vitreous silica matrix. Our results showed a large improvement in the chemical durability of glass ceramic over conventional nuclear glass.

  15. Nanoporous polystyrene fibers for oil spill cleanup.

    Science.gov (United States)

    Lin, Jinyou; Shang, Yanwei; Ding, Bin; Yang, Jianmao; Yu, Jianyong; Al-Deyab, Salem S

    2012-02-01

    The development of oil sorbents with high sorption capacity, low cost, scalable fabrication, and high selectivity is of great significance for water environmental protection, especially for oil spillage on seawater. In this work, we report nanoporous polystyrene (PS) fibers prepared via a one-step electrospinning process used as oil sorbents for oil spill cleanup. The oleophilic-hydrophobic PS oil sorbent with highly porous structures shows a motor oil sorption capacity of 113.87 g/g, approximately 3-4 times that of natural sorbents and nonwoven polypropylene fibrous mats. Additionally, the sorbents also exhibit a relatively high sorption capacity for edible oils, such as bean oil (111.80 g/g) and sunflower seed oil (96.89 g/g). The oil sorption mechanism of the PS sorbent and the sorption kinetics were investigated. Our nanoporous material has great potential for use in wastewater treatment, oil accident remediation and environmental protection. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Global Monte Carlo Simulation with High Order Polynomial Expansions

    Energy Technology Data Exchange (ETDEWEB)

    William R. Martin; James Paul Holloway; Kaushik Banerjee; Jesse Cheatham; Jeremy Conlin

    2007-12-13

    The functional expansion technique (FET) was recently developed for Monte Carlo simulation. The basic idea of the FET is to expand a Monte Carlo tally in terms of a high order expansion, the coefficients of which can be estimated via the usual random walk process in a conventional Monte Carlo code. If the expansion basis is chosen carefully, the lowest order coefficient is simply the conventional histogram tally, corresponding to a flat mode. This research project studied the applicability of using the FET to estimate the fission source, from which fission sites can be sampled for the next generation. The idea is that individual fission sites contribute to expansion modes that may span the geometry being considered, possibly increasing the communication across a loosely coupled system and thereby improving convergence over the conventional fission bank approach used in most production Monte Carlo codes. The project examined a number of basis functions, including global Legendre polynomials as well as “local” piecewise polynomials such as finite element hat functions and higher order versions. The global FET showed an improvement in convergence over the conventional fission bank approach. The local FET methods showed some advantages versus global polynomials in handling geometries with discontinuous material properties. The conventional finite element hat functions had the disadvantage that the expansion coefficients could not be estimated directly but had to be obtained by solving a linear system whose matrix elements were estimated. An alternative fission matrix-based response matrix algorithm was formulated. Studies were made of two alternative applications of the FET, one based on the kernel density estimator and one based on Arnoldi’s method of minimized iterations. Preliminary results for both methods indicate improvements in fission source convergence. These developments indicate that the FET has promise for speeding up Monte Carlo fission source

  17. Recursive regularization step for high-order lattice Boltzmann methods

    Science.gov (United States)

    Coreixas, Christophe; Wissocq, Gauthier; Puigt, Guillaume; Boussuge, Jean-François; Sagaut, Pierre

    2017-09-01

    A lattice Boltzmann method (LBM) with enhanced stability and accuracy is presented for various Hermite tensor-based lattice structures. The collision operator relies on a regularization step, which is here improved through a recursive computation of nonequilibrium Hermite polynomial coefficients. In addition to the reduced computational cost of this procedure with respect to the standard one, the recursive step allows to considerably enhance the stability and accuracy of the numerical scheme by properly filtering out second- (and higher-) order nonhydrodynamic contributions in under-resolved conditions. This is first shown in the isothermal case where the simulation of the doubly periodic shear layer is performed with a Reynolds number ranging from 104 to 106, and where a thorough analysis of the case at Re=3 ×104 is conducted. In the latter, results obtained using both regularization steps are compared against the Bhatnagar-Gross-Krook LBM for standard (D2Q9) and high-order (D2V17 and D2V37) lattice structures, confirming the tremendous increase of stability range of the proposed approach. Further comparisons on thermal and fully compressible flows, using the general extension of this procedure, are then conducted through the numerical simulation of Sod shock tubes with the D2V37 lattice. They confirm the stability increase induced by the recursive approach as compared with the standard one.

  18. A Novel QAM Technique for High Order QAM Signaling

    Directory of Open Access Journals (Sweden)

    A. Ozen

    2011-09-01

    Full Text Available The paper proposes a novel spread quadrature amplitude modulation (S-QAM technique with high SNR improvement for high-order QAM channels. Simulated and experimental bit error rate (BER performance analyses of the proposed technique in blind and non-blind equalizers are obtained by using single carrier (SC WiMAX (IEEE 802.16-2004 radio. Instead of using any one particular type of channel profile, this study concentrates on true frequency selective Rayleigh fading channels in the real-time WiMAX radio environment around 3.5 GHz. The Constant Modulus Algorithm (CMA blind equalizer has been compared with the popular non-blind equalizers, Recursive Least Squares (RLS and Least Mean Squares (LMS algorithm, as benchmarks. It has been proven in experimental and simulated channels that CMA blind equalizer, using the proposed technique, can be considered as a low complexity, spectrum efficient and high performance time domain equalizations to be embedded in a transceiver for the next generation communications. Furthermore the proposed technique has also reduced approximately till 5 dB and 7.5 dB performance differences between non-blind and blind equalizers for 16-QAM and 64-QAM, respectively. The simulation results have demonstrated that the simulated and experimental studies of the proposed technique are compatible with each other and extremely satisfying.

  19. High order harmonic generation with femtosecond mid-infrared laser

    Science.gov (United States)

    Lin, Jinpu; Nees, John; Krushelnick, Karl; Dollar, Franklin; Nguyen, Tam

    2017-10-01

    There has been growing interest in high order harmonic generation (HHG) from laser-solid interactions as a compact source of coherent x-rays. The ponderomotive potential in laser-plasma interactions increases with longer laser wavelength, so there may be significant differences in the physics of harmonic generation and other phenomena when experiments are conducted with mid-infrared lasers. Previous experiments, however, have been done almost exclusively with near-infrared lasers. In this work, we report the results of experiments performed with millijoule, 40 fs, 2 µm laser pulses generated by an optical parametric amplifier (OPA) which are focused onto solid targets such as silicon and glass. The HHG efficiency, polarization dependence, and x-ray emission are studied and compared to measurements with near-infrared lasers. Funded by AFOSR MURI.

  20. High-Order Sparse Linear Predictors for Audio Processing

    DEFF Research Database (Denmark)

    Giacobello, Daniele; van Waterschoot, Toon; Christensen, Mads Græsbøll

    2010-01-01

    of interesting features that make the idea of using it in audio processing not far fetched, e.g., the strong ability of modeling the spectral peaks that play a dominant role in perception. In this paper, we provide some preliminary conjectures and experiments on the use of high-order sparse linear predictors......Linear prediction has generally failed to make a breakthrough in audio processing, as it has done in speech processing. This is mostly due to its poor modeling performance, since an audio signal is usually an ensemble of different sources. Nevertheless, linear prediction comes with a whole set...... in audio processing. These predictors, successfully implemented in modeling the short-term and long-term redundancies present in speech signals, will be used to model tonal audio signals, both monophonic and polyphonic. We will show how the sparse predictors are able to model efficiently the different...

  1. High order integral equation method for diffraction gratings.

    Science.gov (United States)

    Lu, Wangtao; Lu, Ya Yan

    2012-05-01

    Conventional integral equation methods for diffraction gratings require lattice sum techniques to evaluate quasi-periodic Green's functions. The boundary integral equation Neumann-to-Dirichlet map (BIE-NtD) method in Wu and Lu [J. Opt. Soc. Am. A 26, 2444 (2009)], [J. Opt. Soc. Am. A 28, 1191 (2011)] is a recently developed integral equation method that avoids the quasi-periodic Green's functions and is relatively easy to implement. In this paper, we present a number of improvements for this method, including a revised formulation that is more stable numerically, and more accurate methods for computing tangential derivatives along material interfaces and for matching boundary conditions with the homogeneous top and bottom regions. Numerical examples indicate that the improved BIE-NtD map method achieves a high order of accuracy for in-plane and conical diffractions of dielectric gratings. © 2012 Optical Society of America

  2. Role of Rydberg States In High-order Harmonic Generation

    CERN Document Server

    Beaulieu, Samuel; Comby, Antoine; Wanie, Vincent; Petit, Stéphane; Légaré, François; Catoire, Fabrice; Mairesse, Yann

    2016-01-01

    The role of Rydberg states in strong field physics has known a renewed interest in the past few years with the study of resonant high-order harmonic generation. In addition to its fundamental in- terest, this process could create bright sources of coherent vacuum and extreme ultraviolet radiation with controlled polarization state. We investigate the spectral, spatial and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. The intensity-dependence of the emission shows that two different pathways interfere to populate the Rydberg states. Furthermore, we show that the population of Rydberg states can lead to different emission mecanisms: either direct emission through XUV Free Induction Decay, or sequentially with absorption of additional photons, in processes similar to resonance-enhanced multiphoton above- threshold ionization. Last, using the attosecond lighthouse technique we show that the resonant emission from Rydberg states is not temporal...

  3. High-Order Wave Propagation Algorithms for Hyperbolic Systems

    KAUST Repository

    Ketcheson, David I.

    2013-01-22

    We present a finite volume method that is applicable to hyperbolic PDEs including spatially varying and semilinear nonconservative systems. The spatial discretization, like that of the well-known Clawpack software, is based on solving Riemann problems and calculating fluctuations (not fluxes). The implementation employs weighted essentially nonoscillatory reconstruction in space and strong stability preserving Runge--Kutta integration in time. The method can be extended to arbitrarily high order of accuracy and allows a well-balanced implementation for capturing solutions of balance laws near steady state. This well-balancing is achieved through the $f$-wave Riemann solver and a novel wave-slope WENO reconstruction procedure. The wide applicability and advantageous properties of the method are demonstrated through numerical examples, including problems in nonconservative form, problems with spatially varying fluxes, and problems involving near-equilibrium solutions of balance laws.

  4. High-order hydrodynamic algorithms for exascale computing

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Nathaniel Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-05

    Hydrodynamic algorithms are at the core of many laboratory missions ranging from simulating ICF implosions to climate modeling. The hydrodynamic algorithms commonly employed at the laboratory and in industry (1) typically lack requisite accuracy for complex multi- material vortical flows and (2) are not well suited for exascale computing due to poor data locality and poor FLOP/memory ratios. Exascale computing requires advances in both computer science and numerical algorithms. We propose to research the second requirement and create a new high-order hydrodynamic algorithm that has superior accuracy, excellent data locality, and excellent FLOP/memory ratios. This proposal will impact a broad range of research areas including numerical theory, discrete mathematics, vorticity evolution, gas dynamics, interface instability evolution, turbulent flows, fluid dynamics and shock driven flows. If successful, the proposed research has the potential to radically transform simulation capabilities and help position the laboratory for computing at the exascale.

  5. High-order harmonic generation by polyatomic molecules

    Science.gov (United States)

    Odžak, S.; Hasović, E.; Milošević, D. B.

    2017-04-01

    We present a theory of high-order harmonic generation by arbitrary polyatomic molecules based on the molecular strong-field approximation (MSFA) in the framework of the S-matrix theory. A polyatomic molecule is modeled by an (N + 1)-particle system, which consists of N heavy atomic (ionic) centers and an electron. We derived various versions (with or without the dressing of the initial and/or final molecular state) of the MSFA. The general expression for the T-matrix element takes a simple form for neutral polyatomic molecules. We show the existence of the interference minima in the harmonic spectrum and explain these minima as a multiple-slit type of interference. This is illustrated by numerical examples for the nitrous oxide (N2O) molecule exposed to strong linearly polarized laser field.

  6. Stable switching among high-order modes in polariton condensates

    Science.gov (United States)

    Sun, Yongbao; Yoon, Yoseob; Khan, Saeed; Ge, Li; Steger, Mark; Pfeiffer, Loren N.; West, Ken; Türeci, Hakan E.; Snoke, David W.; Nelson, Keith A.

    2018-01-01

    We report multistate optical switching among high-order bouncing-ball modes ("ripples") and whispering-gallery modes ("petals") of exciton-polariton condensates in a laser-generated annular trap. By tailoring the diameter and power of the annular trap, the polariton condensate can be switched among different trapped modes, accompanied by redistribution of spatial densities and superlinear increase in the emission intensities, implying that polariton condensates in this geometry could be exploited for an all-optical multistate switch. A model based on non-Hermitian modes of the generalized Gross-Pitaevskii equation reveals that this mode switching arises from competition between pump-induced gain and in-plane polariton loss. The parameters for reproducible switching among trapped modes have been measured experimentally, giving us a phase diagram for mode switching. Taken together, the experimental result and theoretical modeling advance our fundamental understanding of the spontaneous emergence of coherence and move us toward its practical exploitation.

  7. Anisotropic diffusion of water molecules in hydroxyapatite nanopores

    Science.gov (United States)

    Prakash, Muthuramalingam; Lemaire, Thibault; Caruel, Matthieu; Lewerenz, Marius; de Leeuw, Nora H.; Di Tommaso, Devis; Naili, Salah

    2017-07-01

    New insights into the dynamical properties of water in hydroxyapatite (HAP) nanopores, a model system for the fluid flow within nanosize spaces inside the collagen-apatite structure of bone, were obtained from molecular dynamics simulations of liquid water confined between two parallel HAP surfaces of different sizes (20 Å ≤ H ≤ 240 Å). Calculations were conducted using a core-shell interatomic potential for HAP together with the extended simple point charge model for water. This force field gives an activation energy for water diffusion within HAP nanopores that is in excellent agreement with available experimental data. The dynamical properties of water within the HAP nanopores were quantified in terms of the second-order water diffusion tensor. Results indicate that water diffuses anisotropically within the HAP nanopores, with the solvent molecules moving parallel to the surface twice as fast as the perpendicular direction. This unusual dynamic behaviour is linked to the strong polarizing effect of calcium ions, and the synergic interactions between the water molecules in the first hydration layer of HAP with the calcium, hydroxyl, and phosphate ions, which facilitates the flow of water molecules in the directions parallel to the HAP surface.

  8. Cluster size dependence of high-order harmonic generation

    Science.gov (United States)

    Tao, Y.; Hagmeijer, R.; Bastiaens, H. M. J.; Goh, S. J.; van der Slot, P. J. M.; Biedron, S. G.; Milton, S. V.; Boller, K.-J.

    2017-08-01

    We investigate high-order harmonic generation (HHG) from noble gas clusters in a supersonic gas jet. To identify the contribution of harmonic generation from clusters versus that from gas monomers, we measure the high-order harmonic output over a broad range of the total atomic number density in the jet (from 3×1016 to 3 × 1018 {{cm}}-3) at two different reservoir temperatures (303 and 363 K). For the first time in the evaluation of the harmonic yield in such measurements, the variation of the liquid mass fraction, g, versus pressure and temperature is taken into consideration, which we determine, reliably and consistently, to be below 20% within our range of experimental parameters. By comparing the measured harmonic yield from a thin jet with the calculated corresponding yield from monomers alone, we find an increased emission of the harmonics when the average cluster size is less than 3000. Using g, under the assumption that the emission from monomers and clusters add up coherently, we calculate the ratio of the average single-atom response of an atom within a cluster to that of a monomer and find an enhancement of around 100 for very small average cluster size (∼200). We do not find any dependence of the cut-off frequency on the composition of the cluster jet. This implies that HHG in clusters is based on electrons that return to their parent ions and not to neighboring ions in the cluster. To fully employ the enhanced average single-atom response found for small average cluster sizes (∼200), the nozzle producing the cluster jet must provide a large liquid mass fraction at these small cluster sizes for increasing the harmonic yield. Moreover, cluster jets may allow for quasi-phase matching, as the higher mass of clusters allows for a higher density contrast in spatially structuring the nonlinear medium.

  9. Low-cost photoelectrocatalyst based on a nanoporous oxide layer of low-carbon steel

    Science.gov (United States)

    Rangaraju, Raghu R.; Raja, K. S.; Panday, A.; Misra, M.

    2010-11-01

    Low-carbon steel is a commonly used structural material in a wide variety of applications. An anodic oxide layer of this inexpensive alloy has been noted to have interesting photoelectrochemical behaviour similar to that of α-Fe2O3 prepared using other expensive starting materials. An ordered nanoporous oxide layer has been grown on to the low-carbon steel surface by a simple electrochemical anodization process in different electrolytes such as ethylene glycol containing 0.05M NH4F and 3-10 vol% water and 0.5M phosphoric acid solution containing 0.05M NH4F. After anodization, the nanoporous anodic oxide layer has been transformed to α-Fe2O3 by a low-temperature annealing process. Photoelectrochemical characterization of the anodic iron oxide materials has been carried out in 1M KOH electrolyte under a solar simulated illumination using Air Mass (AM) 1.5. The ordered nanoporous oxide layer prepared in ethylene glycol-based electrolyte showed a photocurrent density of about 85 µA cm-2 at 0.4 VAg/AgCl. Whereas the anodic iron oxide prepared by anodization of the low-carbon steel in 0.5M H3PO4 + 0.05M NaF solution showed a photocurrent density of 800 µA cm-2 at 0.4 VAg/AgCl. The improved photoactivity of the phosphate-modified oxide layer could be attributed to the high charge carrier concentration, low charge transfer resistance and better ability to expend holes in the oxygen evolution reaction.

  10. Ultrafast nanoscale imaging using high order harmonic generation (Conference Presentation)

    Science.gov (United States)

    Merdji, Hamed

    2017-05-01

    Ultrafast coherent diffraction using soft and hard X-rays is actually revolutionizing imaging science thanks to new sources recently available. This powerful technique extends standard X-ray diffraction towards imaging of non-crystalline objects and leads actually to a strong impact in physics, chemistry and biology. New ultrashort pulses recently available hold the promise of watching matter evolving with unprecedented space and time resolution. Femtosecond coherent and intense radiation in the soft X-ray (λ = 10-40 nm) is currently produced in our laboratory, from highly non linear frequency conversion (high harmonic generation). A high intensity UV-X coherent beam is obtained using a loose focusing geometry, which allows coupling a very high amount of Ti:Sapphire laser system energy in the HHG process. Using a long gas cell and a long focal length lens, the emitting volume can be increased by orders of magnitude compared to standard HHG set-ups. This approach, allows reaching up to 1x1011 photons per shot for the 25th harmonic (λ=32nm). We have already demonstrated nanoscale imaging in a single shot mode reaching 70 nm spatial resolution and 20 femtoseconds snapshot [1]. We then implemented a recently proposed holographic technique using extended references. This technique, easy to implement, allows a direct non iterative image reconstruction. In the single shot regime, we demonstrated a spatial resolution of 110nm [2].This opens fascinating perspectives in imaging dynamical phenomena to be spread over a large scientific community. I will present recent results in the investigation of femtosecond phase spin-reversals of magnetic nano-domains [3]. Finally, I will report on recent development on noise sensitivity of the technique and perspectives in attosecond coherent imaging [4]. [1] A. Ravasio et al., Physical Review Letters 103, 028104 (2009). [2] D. Gauthier et al., Physical Review Letters 105, 093901 (2010). [3] Vodungbo et al., Nature Communications 3

  11. Electrochemically etched nanoporous silicon membrane for separation of biological molecules in mixture

    Science.gov (United States)

    Burham, Norhafizah; Azlan Hamzah, Azrul; Yunas, Jumril; Yeop Majlis, Burhanuddin

    2017-07-01

    This paper presents a technique for separating biological molecules in mixture using nanoporous silicon membrane. Nanopores were formed using electrochemical etching process (ECE) by etching a prefabricated silicon membrane in hydrofluoric acid (HF) and ethanol, and then directly bonding it with PDMS to form a complete filtration system for separating biological molecules. Tygon S3™ tubings were used as fluid interconnection between PDMS molds and silicon membrane during testing. Electrochemical etching parameters were manipulated to control pore structure and size. In this work, nanopores with sizes of less than 50 nm, embedded on top of columnar structures have been fabricated using high current densities and variable HF concentrations. Zinc oxide was diluted with deionized (DI) water and mixed with biological molecules and non-biological particles, namely protein standard, serum albumin and sodium chloride. Zinc oxide particles were trapped on the nanoporous silicon surface, while biological molecules of sizes up to 12 nm penetrated the nanoporous silicon membrane. The filtered particles were inspected using a Zetasizer Nano SP for particle size measurement and count. The Zetasizer Nano SP results revealed that more than 95% of the biological molecules in the mixture were filtered out by the nanoporous silicon membrane. The nanoporous silicon membrane fabricated in this work is integratable into bio-MEMS and Lab-on-Chip components to separate two or more types of biomolecules at once. The membrane is especially useful for the development of artificial kidney.

  12. Molecular Dynamics Simulation of the Effect of Angle Variation on Water Permeability through Hourglass-Shaped Nanopores.

    Science.gov (United States)

    Tang, Dai; Li, Longnan; Shahbabaei, Majid; Yoo, Yeong-Eun; Kim, Daejoong

    2015-10-29

    Water transport through aquaporin water channels occurs extensively in cell membranes. Hourglass-shaped (biconical) pores resemble the geometry of these aquaporin channels and therefore attract much research attention. We assumed that hourglass-shaped nanopores are capable of high water permeation like biological aquaporins. In order to prove the assumption, we investigated nanoscale water transport through a model hourglass-shaped pore using molecular dynamics simulations while varying the angle of the conical entrance and the total nanopore length. The results show that a minimal departure from optimized cone angle (e.g., 9° for 30 Å case) significantly increases the osmotic permeability and that there is a non-linear relationship between permeability and the cone angle. The analysis of hydrodynamic resistance proves that the conical entrance helps to reduce the hydrodynamic entrance hindrance. Our numerical and analytical results thus confirm our initial assumption and suggest that fast water transport can be achieved by adjusting the cone angle and length of an hourglass-shaped nanopore.

  13. Molecular Dynamics Simulation of the Effect of Angle Variation on Water Permeability through Hourglass-Shaped Nanopores

    Directory of Open Access Journals (Sweden)

    Dai Tang

    2015-10-01

    Full Text Available Water transport through aquaporin water channels occurs extensively in cell membranes. Hourglass-shaped (biconical pores resemble the geometry of these aquaporin channels and therefore attract much research attention. We assumed that hourglass-shaped nanopores are capable of high water permeation like biological aquaporins. In order to prove the assumption, we investigated nanoscale water transport through a model hourglass-shaped pore using molecular dynamics simulations while varying the angle of the conical entrance and the total nanopore length. The results show that a minimal departure from optimized cone angle (e.g., 9° for 30 Å case significantly increases the osmotic permeability and that there is a non-linear relationship between permeability and the cone angle. The analysis of hydrodynamic resistance proves that the conical entrance helps to reduce the hydrodynamic entrance hindrance. Our numerical and analytical results thus confirm our initial assumption and suggest that fast water transport can be achieved by adjusting the cone angle and length of an hourglass-shaped nanopore.

  14. High and stable photoelectrochemical activity of ZnO/ZnSe/CdSe/Cu(x)S core-shell nanowire arrays: nanoporous surface with Cu(x)S as a hole mediator.

    Science.gov (United States)

    Ouyang, Wei-Xin; Yu, Yu-Xiang; Zhang, Wei-De

    2015-06-14

    Advanced materials for electrocatalytic and photoelectrochemical water splitting are key for taking advantage of renewable energy. In this study, ZnO/ZnSe/CdSe/Cu(x)S core-shell nanowire arrays with a nanoporous surface were fabricated via ion exchange and successive ionic layer adsorption and reaction (SILAR) processes. The ZnO/ZnSe/CdSe/Cu(x)S sample displays a high photocurrent density of 12.0 mA cm(-2) under AM 1.5G illumination, achieves the highest IPCE value of 89.5% at 500 nm at a bias potential of 0.2 V versus Ag/AgCl, and exhibits greatly improved photostability. The functions of the ZnSe, CdSe, and Cu(x)S layers in the ZnO/ZnSe/CdSe/Cu(x)S heterostructure were clarified. ZnSe is used as a passivation layer to reduce the trapping and recombination of charge carriers at the interfaces of the semiconductors. CdSe functions as a highly efficient visible light absorber and builds heterojunctions with the other components to improve the separation and transportation of the photoinduced electrons and holes. Cu(x)S serves as a passivation layer and an effective p-type hole mediator, which passivates the defects and surface states of the semiconductors and forms p-n junctions with CdSe to promote the hole transportation at the semiconductor-electrolyte interface. The nanoporous surface of the ZnO/ZnSe/CdSe/Cu(x)S core-shell nanowire arrays, together with the tunnel transportation of the charge carriers in the thin films of ZnSe and CdSe, also facilitates the kinetics of photoelectrochemical reactions and improves the optical absorption as well.

  15. Mode of conception of triplets and high order multiple pregnancies.

    LENUS (Irish Health Repository)

    Basit, I

    2012-03-01

    A retrospective audit was performed of all high order multiple pregnancies (HOMPs) delivered in three maternity hospitals in Dublin between 1999 and 2008. The mode of conception for each pregnancy was established with a view to determining means of reducing their incidence. A total of 101 HOMPs occurred, 93 triplet, 7 quadruplet and 1 quintuplet. Information regarding the mode of conception was available for 78 (81%) pregnancies. Twenty eight (27.7%) were spontaneous, 34 (33.7%) followedlVF\\/ICSI\\/FET treatment (in-vitro fertilisation, intracytoplasmic sperm injection, frozen embryo transfer), 16 (15.8%) resulted from Clomiphene Citrate treatment and 6 (6%) followed ovulation induction with gonadotrophins. Triplet and HOMPs are a major cause of maternal, feta land neonatal morbidity. Many are iatrogenic, arising from fertility treatments including Clomiphene. Reducing the numbers of embryos transferred will address IVF\\/ICSI\\/FET-related multiple pregnancy rates and this is currently happening in Ireland. Clomiphene and gonadotrophins should only be prescribed when appropriate resources are available to monitor patients adequately.

  16. High-order WENO scheme for polymerization-type equations*

    Directory of Open Access Journals (Sweden)

    Gabriel Pierre

    2010-12-01

    Full Text Available Polymerization of proteins is a biochemical process involved in different diseases. Mathematically, it is generally modeled by aggregation-fragmentation-type equations. In this paper we consider a general polymerization model and propose a high-order numerical scheme to investigate the behavior of the solution. An important property of the equation is the mass conservation. The WENO scheme is built to preserve the total mass of proteins along time. Le processus biophysique de polymérisation de protéines entre en jeu dans différentes maladies. Mathématiquement, ceci est généralement modélisé par des équations de type agrégation-fragmentation. Dans cet article nous considérons un modèle général de polymérisation et proposons un schéma d’ordre élevé pour sa résolution numérique. Une propriété importante de l’équation est la conservation de la masse. Le schéma WENO est construit pour conserver la masse totale de protéines au cours du temps.

  17. Stirling Analysis Comparison of Commercial vs. High-Order Methods

    Science.gov (United States)

    Dyson, Rodger W.; Wilson, Scott D.; Tew, Roy C.; Demko, Rikako

    2007-01-01

    Recently, three-dimensional Stirling engine simulations have been accomplished utilizing commercial Computational Fluid Dynamics software. The validations reported can be somewhat inconclusive due to the lack of precise time accurate experimental results from engines, export control/ proprietary concerns, and the lack of variation in the methods utilized. The last issue may be addressed by solving the same flow problem with alternate methods. In this work, a comprehensive examination of the methods utilized in the commercial codes is compared with more recently developed high-order methods. Specifically, Lele's Compact scheme and Dyson s Ultra Hi-Fi method will be compared with the SIMPLE and PISO methods currently employed in CFD-ACE, FLUENT, CFX, and STAR-CD (all commercial codes which can in theory solve a three-dimensional Stirling model although sliding interfaces and their moving grids limit the effective time accuracy). We will initially look at one-dimensional flows since the current standard practice is to design and optimize Stirling engines with empirically corrected friction and heat transfer coefficients in an overall one-dimensional model. This comparison provides an idea of the range in which commercial CFD software for modeling Stirling engines may be expected to provide accurate results. In addition, this work provides a framework for improving current one-dimensional analysis codes.

  18. Stirling Analysis Comparison of Commercial Versus High-Order Methods

    Science.gov (United States)

    Dyson, Rodger W.; Wilson, Scott D.; Tew, Roy C.; Demko, Rikako

    2005-01-01

    Recently, three-dimensional Stirling engine simulations have been accomplished utilizing commercial Computational Fluid Dynamics software. The validations reported can be somewhat inconclusive due to the lack of precise time accurate experimental results from engines, export control/proprietary concerns, and the lack of variation in the methods utilized. The last issue may be addressed by solving the same flow problem with alternate methods. In this work, a comprehensive examination of the methods utilized in the commercial codes is compared with more recently developed high-order methods. Specifically, Lele's compact scheme and Dyson's Ultra Hi-Fi method will be compared with the SIMPLE and PISO methods currently employed in CFD-ACE, FLUENT, CFX, and STAR-CD (all commercial codes which can in theory solve a three-dimensional Stirling model with sliding interfaces and their moving grids limit the effective time accuracy). We will initially look at one-dimensional flows since the current standard practice is to design and optimize Stirling engines with empirically corrected friction and heat transfer coefficients in an overall one-dimensional model. This comparison provides an idea of the range in which commercial CFD software for modeling Stirling engines may be expected to provide accurate results. In addition, this work provides a framework for improving current one-dimensional analysis codes.

  19. Plasma channel undulator excited by high-order laser modes

    Science.gov (United States)

    Wang, Jingwei; Schroeder, Carl; Zepf, Matt; Rykovanov, Sergey

    2017-10-01

    The possibility of utilizing plasma undulators and plasma accelerators to produce compact and economical ultraviolet and X-ray radiation sources has attracted considerable interest for a few decades. This interest has been driven by the great potential to decrease the threshold for accessing such sources, which are now mainly provided by a very few dedicated large-scale synchrotron or free-electron laser (FEL) facilities. However, the typically broad radiation bandwidth of such plasma devices limits the source brightness and makes it difficult for the FEL instability to develop. Here, using multi-dimensional electromagnetic particle-in-cell simulations, we demonstrate that a plasma undulator generated by the beating of a mixture of high-order laser modes propagating inside a plasma channel, leads to a few percent radiation bandwidth. The strength of the undulator can reach unity, the period can be less than a millimeter, and the total number of undulator periods can be significantly increased by a phase locking technique based on the longitudinal density modulation. According to analytical estimates and simulations, in the fully beam loaded regime, the electron current in the undulator can reach 0.3 kA, making such an undulator a potential candidate towards a table-top FEL.

  20. High order shear horizontal modes for minimum remnant thickness.

    Science.gov (United States)

    Belanger, Pierre

    2014-04-01

    Thickness mapping in aging structures suffering from corrosion is challenging especially when the structure is only partially accessible. In plates the high order shear horizontal guided wave modes all have a cutoff frequency thickness product below which they cannot propagate. This property is potentially attractive to estimate the minimum remnant thickness between two transducers. When using a source and a sensor array it is possible to control the number of modes being excited and the size of the region interrogated by the technique. Finite element simulations were used to show that by exciting multiple guided wave modes simultaneously and identifying which modes are received by a sensor array it is possible to estimate the minimum remaining thickness along the propagation path. Initial experimental results showed excellent agreement with the finite element simulations when the plate is uniform and with a thickness reduction between the source and the sensor arrays the minimum remnant thickness was underestimated by approximately 20%. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Hollow nanoporous covalent triazine frameworks via acid vapor-assisted solid phase synthesis for enhanced visible light photoactivity

    KAUST Repository

    Huang, Wei

    2016-04-11

    Herein, we report a novel trifluoromethanesulfonic acid vapor-assisted solid phase synthetic method to construct nanoporous covalent triazine frameworks with highly ordered hollow interconnected pores under mild reaction conditions. This unique solid state synthetic route allows not only the avoidance of undesired side reactions caused by traditional high temperature synthesis, but also the maintaining of defined and precise optical and electronic properties of the nonporous triazine frameworks. Promising photocatalytic activity of the polytriazine networks was demonstrated in the photoreduction reaction of 4-nitrophenol into 4-aminophenol under visible light irradiation.

  2. Nanoporous hybrid electrolytes

    KAUST Repository

    Schaefer, Jennifer L.

    2011-01-01

    Oligomer-suspended SiO2-polyethylene glycol nanoparticles are studied as porous media electrolytes. At SiO2 volume fractions, , bracketing a critical value y ≈ 0.29, the suspensions jam and their mechanical modulus increase by more than seven orders. For >y, the mean pore diameter is close to the anion size, yet the ionic conductivity remains surprisingly high and can be understood, at all , using a simple effective medium model proposed by Maxwell. SiO 2-polyethylene glycol hybrid electrolytes are also reported to manifest attractive electrochemical stability windows (0.3-6.3 V) and to reach a steady-state interfacial impedance when in contact with metallic lithium. © 2010 The Royal Society of Chemistry.

  3. Nanofluidic control by nanoporous materials using electrocapillary effects

    Science.gov (United States)

    Xue, Yahui; Duan, Huiling; Markmann, Juergen; Huber, Patrick; Weissmueller, Joerg

    2014-11-01

    Electrocapillary techniques exhibit great advantages in nonmechanical electrofluidic manipulation, e.g., flow actuation in micro-/nano-channels. One issue of interest is the spontaneous imbibition of fluids in bodies with a nanoscale pores size. Contrary to previous studies we here use a metallic nanoporous body. This allows us to control the electrode potential at the solid-fluid interface. Nanoporous gold (NPG) with uniform pore- and ligament size of 45 nm was fabricated by dealloying an Ag75Au25 alloy. Spontaneous imbibition of aqueous electrolytes obeys the Lucas-Washburn law. Interestingly, the estimated tortuosity has the low value of 3.2 (3 is expected for an isotropic sponge). Electrocapillary effects were then used to manipulate the imbibition dynamics. As a result of the enhanced wetting by the electrocapillary effects, we observed an acceleration of the imbibition by 30%. When air as the pore fluid is replaced with cyclohexane, we show for aqueous electrolyte imbibition in nanoporous gold that the fluid flow can be reversibly switched on and off through electric potential control of the solid-liquid interfacial tension. Our findings demonstrate that the high electric conductivity along with the pathways for fluid/ionic transport render nanoporous gold a versatile, accurately controllable electrocapillary pump and flow sensor for minute amounts of liquids with exceptionally low operating voltages.

  4. Hydrogen storage in nanoporous carbon materials: myth and facts.

    Science.gov (United States)

    Kowalczyk, Piotr; Hołyst, Robert; Terrones, Mauricio; Terrones, Humberto

    2007-04-21

    We used Grand canonical Monte Carlo simulation to model the hydrogen storage in the primitive, gyroid, diamond, and quasi-periodic icosahedral nanoporous carbon materials and in carbon nanotubes. We found that none of the investigated nanoporous carbon materials satisfy the US Department of Energy goal of volumetric density and mass storage for automotive application (6 wt% and 45 kg H(2) m(-3)) at considered storage condition. Our calculations indicate that quasi-periodic icosahedral nanoporous carbon material can reach the 6 wt% at 3.8 MPa and 77 K, but the volumetric density does not exceed 24 kg H(2) m(-3). The bundle of single-walled carbon nanotubes can store only up to 4.5 wt%, but with high volumetric density of 42 kg H(2) m(-3). All investigated nanoporous carbon materials are not effective against compression above 20 MPa at 77 K because the adsorbed density approaches the density of the bulk fluid. It follows from this work that geometry of carbon surfaces can enhance the storage capacity only to a limited extent. Only a combination of the most effective structure with appropriate additives (metals) can provide an efficient storage medium for hydrogen in the quest for a source of "clean" energy.

  5. Modeling gas flow through microchannels and nanopores

    Science.gov (United States)

    Roy, Subrata; Raju, Reni; Chuang, Helen F.; Cruden, Brett A.; Meyyappan, M.

    2003-04-01

    Microchannel based systems have emerged as a critical design trend in development of precise control and maneuvering of small devices. In microelectronics, space propulsion and biomedical areas, these systems are especially useful. Nanoscale pores are recently becoming of great interest due to their beneficial drag and heat transfer properties. However it is difficult to predict the flow performance of these microsystems and nanosystems numerically since the standard assumptions of using Navier-Stokes equations break down at micrometer scales, while the computational times of applicable molecular-dynamics codes become exorbitant. A two-dimensional finite-element based microscale flow model is developed to efficiently predict the overall flow characteristics up to the transition regime for reasonably high Knudsen number flow inside microchannels and nanopores. Presented two-dimensional numerical results for Poiseuille flow of a simple fluid through the microchannel are comparable to the numerical and experimental data published in the literature. The nanopore solutions are also validated with presented experimental data.

  6. Asymmetric Supercapacitors Using 3D Nanoporous Carbon and Cobalt Oxide Electrodes Synthesized from a Single Metal-Organic Framework.

    Science.gov (United States)

    Salunkhe, Rahul R; Tang, Jing; Kamachi, Yuichiro; Nakato, Teruyuki; Kim, Jung Ho; Yamauchi, Yusuke

    2015-06-23

    Nanoporous carbon and nanoporous cobalt oxide (Co3O4) materials have been selectively prepared from a single metal-organic framework (MOF) (zeolitic imidazolate framework, ZIF-67) by optimizing the annealing conditions. The resulting ZIF-derived carbon possesses highly graphitic walls and a high specific surface area of 350 m(2)·g(-1), while the resulting ZIF-derived nanoporous Co3O4 possesses a high specific surface area of 148 m(2)·g(-1) with much less carbon content (1.7 at%). When nanoporous carbon and nanoporous Co3O4 were tested as electrode materials for supercapacitor application, they showed high capacitance values (272 and 504 F·g(-1), respectively, at a scan rate of 5 mV·s(-1)). To further demonstrate the advantages of our ZIF-derived nanoporous materials, symmetric (SSCs) and asymmetric supercapacitors (ASCs) were also fabricated using nanoporous carbon and nanoporous Co3O4 electrodes. Improved capacitance performance was successfully realized for the ASC (Co3O4//carbon), better than those of the SSCs based on nanoporous carbon and nanoporous Co3O4 materials (i.e., carbon//carbon and Co3O4//Co3O4). The developed ASC with an optimal mass loading can be operated within a wide potential window of 0.0-1.6 V, which leads to a high specific energy of 36 W·h·kg(-1). More interestingly, this ASC also exhibits excellent rate capability (with the highest specific power of 8000 W·kg(-1) at a specific energy of 15 W·h·kg(-1)) combined with long-term stability up to 2000 cycles.

  7. High-order-harmonic generation in atomic and molecular systems

    Science.gov (United States)

    Suárez, Noslen; Chacón, Alexis; Pérez-Hernández, Jose A.; Biegert, Jens; Lewenstein, Maciej; Ciappina, Marcelo F.

    2017-03-01

    High-order-harmonic generation (HHG) results from the interaction of ultrashort laser pulses with matter. It configures an invaluable tool to produce attosecond pulses, moreover, to extract electron structural and dynamical information of the target, i.e., atoms, molecules, and solids. In this contribution, we introduce an analytical description of atomic and molecular HHG, that extends the well-established theoretical strong-field approximation (SFA). Our approach involves two innovative aspects: (i) First, the bound-continuum and rescattering matrix elements can be analytically computed for both atomic and multicenter molecular systems, using a nonlocal short range model, but separable, potential. When compared with the standard models, these analytical derivations make possible to directly examine how the HHG spectra depend on the driven media and laser-pulse features. Furthermore, we can turn on and off contributions having distinct physical origins or corresponding to different mechanisms. This allows us to quantify their importance in the various regions of the HHG spectra. (ii) Second, as reported recently [N. Suárez et al., Phys. Rev. A 94, 043423 (2016), 10.1103/PhysRevA.94.043423], the multicenter matrix elements in our theory are free from nonphysical gauge- and coordinate-system-dependent terms; this is accomplished by adapting the coordinate system to the center from which the corresponding time-dependent wave function originates. Our SFA results are contrasted, when possible, with the direct numerical integration of the time-dependent Schrödinger equation in reduced and full dimensionality. Very good agreement is found for single and multielectronic atomic systems, modeled under the single active electron approximation, and for simple diatomic molecular systems. Interference features, ubiquitously present in every strong-field phenomenon involving a multicenter target, are also captured by our model.

  8. High-Order Numerical Simulations of Wind Turbine Wakes

    Science.gov (United States)

    Kleusberg, E.; Mikkelsen, R. F.; Schlatter, P.; Ivanell, S.; Henningson, D. S.

    2017-05-01

    Previous attempts to describe the structure of wind turbine wakes and their mutual interaction were mostly limited to large-eddy and Reynolds-averaged Navier-Stokes simulations using finite-volume solvers. We employ the higher-order spectral-element code Nek5000 to study the influence of numerical aspects on the prediction of the wind turbine wake structure and the wake interaction between two turbines. The spectral-element method enables an accurate representation of the vortical structures, with lower numerical dissipation than the more commonly used finite-volume codes. The wind-turbine blades are modeled as body forces using the actuator-line method (ACL) in the incompressible Navier-Stokes equations. Both tower and nacelle are represented with appropriate body forces. An inflow boundary condition is used which emulates homogeneous isotropic turbulence of wind-tunnel flows. We validate the implementation with results from experimental campaigns undertaken at the Norwegian University of Science and Technology (NTNU Blind Tests), investigate parametric influences and compare computational aspects with existing numerical simulations. In general the results show good agreement between the experiments and the numerical simulations both for a single-turbine setup as well as a two-turbine setup where the turbines are offset in the spanwise direction. A shift in the wake center caused by the tower wake is detected similar to experiments. The additional velocity deficit caused by the tower agrees well with the experimental data. The wake is captured well by Nek5000 in comparison with experiments both for the single wind turbine and in the two-turbine setup. The blade loading however shows large discrepancies for the high-turbulence, two-turbine case. While the experiments predicted higher thrust for the downstream turbine than for the upstream turbine, the opposite case was observed in Nek5000.

  9. Optimized low-order explicit Runge-Kutta schemes for high- order spectral difference method

    KAUST Repository

    Parsani, Matteo

    2012-01-01

    Optimal explicit Runge-Kutta (ERK) schemes with large stable step sizes are developed for method-of-lines discretizations based on the spectral difference (SD) spatial discretization on quadrilateral grids. These methods involve many stages and provide the optimal linearly stable time step for a prescribed SD spectrum and the minimum leading truncation error coefficient, while admitting a low-storage implementation. Using a large number of stages, the new ERK schemes lead to efficiency improvements larger than 60% over standard ERK schemes for 4th- and 5th-order spatial discretization.

  10. Preparation of nanoporous graphene sheets via free radical oxidation of graphene oxide and their application in lithium ion battery

    Science.gov (United States)

    Zhou, Xuejiao; Xu, Liangyou; Ma, Xiaohua

    2017-07-01

    Graphene is an attractive candidate for use as an electrode material in electrochemical energy storage due to its unique structure and excellent properties. Compared with graphene, nanoporous graphene is a superior electrode material, owing to the porous structure of its graphene sheets, which facilitates cross-plane lithium ion transportation and provides more binding sites for the lithium ions during the lithiation/delithiation process. In this work, we demonstrate a simple and efficient strategy for obtaining nanoporous graphene on a large scale. Nanoporous graphene can be generated through the oxidation of graphene oxide by H2O2 under high-power UV irradiation with a subsequent reduction process. The morphology, chemical composition and defects of the as-generated nanoporous graphene were studied. The electrochemical evaluation of the nanoporous graphene sheets showed that it delivered higher specific capacity and better charge/discharge rate capability compared with chemically reduced graphene sheets for use as an anode material in lithium ion batteries.

  11. High-order harmonic generation using a high-repetition-rate turnkey laser

    CERN Document Server

    Lorek, Eleonora; Heyl, Christoph Michael; Carlström, Stefanos; Paleček, David; Zigmantas, Donatas; Mauritsson, Johan

    2014-01-01

    We generate high-order harmonics at high pulse repetition rates using a turnkey laser. High-order harmonics at 400 kHz are observed when argon is used as target gas. In neon we achieve generation of photons with energies exceeding 90 eV ($\\sim$13 nm) at 20 kHz. We measure a photon flux of 4.4$\\cdot10^{10}$ photons per second per harmonic in argon at 100 kHz. Many experiments employing high-order harmonics would benefit from higher repetition rates, and the user-friendly operation opens up for applications of coherent extreme ultra-violet pulses in new research areas.

  12. Synthesis and Characterization of Bimodal Nanoporous Cu Foams: Working Towards Inertial Fusion Energy

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, O; Hayes, J R; Hamza, A

    2007-09-28

    For the National Ignition Facility, at the Lawrence Livermore National Laboratory, nanoporous structures play a crucial role in the development of targets for high energy density experiments. Here we present a new bottom-up synthesis technique termed filter-casting for the creation of bimodal macro/nanoporous Cu structures. Homogeneous nanoporous monoliths can be synthesized using Cu nanoparticles and bimodal porosities can be achieved using sacrificial polystyrene spheres as a template. Control over the structure and composition is critical for target manufacturing. The measured densities of the Cu foam range between 1070-3390 mg/cm{sup 3}. Filter-casting is a powerful new method for directly synthesizing large nanoporous monoliths with predetermined composition, pore size, and pore structure.

  13. High order boron transport scheme in TRAC-BF1

    Energy Technology Data Exchange (ETDEWEB)

    Barrachina, Teresa; Jambrina, Ana; Miro, Rafael; Verdu, Gumersindo, E-mail: tbarrachina@iqn.upv.es, E-mail: rmiro@iqn.upv.es, E-mail: gverdu@iqn.upv.es [Universidade Politecnica de Valencia (UPV), Valencia, (Spain). Institute for the Industrial, Radiophysical and Environmental Safety; Soler, Amparo, E-mail: asoler@iberdrola.es [SEA Propulsion S.L., Madrid (Spain); Concejal, Alberto, E-mail: acbe@iberdrola.es [Iberdrola Ingenieria y Construcion S.A.U, Madrid (Spain)

    2013-07-01

    In boiling water reactors (BWR), unlike pressurized water reactors (PWR) in which the reactivity control is accomplished through movement of the control rods and boron dilution, the importance of boron transport lies in maintaining the core integrity during ATWS-kind severe accidents in which under certain circumstances a boron injection is required. This is the reason for implementing boron transport models thermal-hydraulic codes as TRAC-BF1, RELAP5 and TRACE, bringing an improvement in the accuracy of the simulations. TRAC-BF1 code provides a best estimate analysis capability for the analysis of the full range of postulated accidents in boiling water reactors systems and related facilities. The boron transport model implemented in TRAC-BF1 code is based on a calculation according to a first order accurate upwind difference scheme. There is a need in reviewing and improving this model. Four numerical schemes that solve the boron transport model have been analyzed and compared with the analytical solution that provides the Burgers equation. The studied numerical schemes are: first order Upwind, second order Godunov, second-order modified Godunov adding physical diffusion term and a third-order QUICKEST using the ULTIMATE universal limiter (UL). The modified Godunov scheme has been implemented in TRAC-BF1 source code. The results using these new schemes are presented in this paper. (author)

  14. High-order upwind schemes for the wave equation on overlapping grids: Maxwell's equations in second-order form

    Science.gov (United States)

    Angel, Jordan B.; Banks, Jeffrey W.; Henshaw, William D.

    2018-01-01

    High-order accurate upwind approximations for the wave equation in second-order form on overlapping grids are developed. Although upwind schemes are well established for first-order hyperbolic systems, it was only recently shown by Banks and Henshaw [1] how upwinding could be incorporated into the second-order form of the wave equation. This new upwind approach is extended here to solve the time-domain Maxwell's equations in second-order form; schemes of arbitrary order of accuracy are formulated for general curvilinear grids. Taylor time-stepping is used to develop single-step space-time schemes, and the upwind dissipation is incorporated by embedding the exact solution of a local Riemann problem into the discretization. Second-order and fourth-order accurate schemes are implemented for problems in two and three space dimensions, and overlapping grids are used to treat complex geometry and problems with multiple materials. Stability analysis of the upwind-scheme on overlapping grids is performed using normal mode theory. The stability analysis and computations confirm that the upwind scheme remains stable on overlapping grids, including the difficult case of thin boundary grids when the traditional non-dissipative scheme becomes unstable. The accuracy properties of the scheme are carefully evaluated on a series of classical scattering problems for both perfect conductors and dielectric materials in two and three space dimensions. The upwind scheme is shown to be robust and provide high-order accuracy.

  15. Nanoporous-carbon adsorbers for chemical microsensors.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Staton, Alan W.; Provencio, Paula Polyak; Yelton, William Graham

    2004-11-01

    Chemical microsensors rely on partitioning of airborne chemicals into films to collect and measure trace quantities of hazardous vapors. Polymer sensor coatings used today are typically slow to respond and difficult to apply reproducibly. The objective of this project was to produce a durable sensor coating material based on graphitic nanoporous-carbon (NPC), a new material first studied at Sandia, for collection and detection of volatile organic compounds (VOC), toxic industrial chemicals (TIC), chemical warfare agents (CWA) and nuclear processing precursors (NPP). Preliminary studies using NPC films on exploratory surface-acoustic-wave (SAW) devices and as a {micro}ChemLab membrane preconcentrator suggested that NPC may outperform existing, irreproducible coatings for SAW sensor and {micro}ChemLab preconcentrator applications. Success of this project will provide a strategic advantage to the development of a robust, manufacturable, highly-sensitive chemical microsensor for public health, industrial, and national security needs. We use pulsed-laser deposition to grow NPC films at room-temperature with negligible residual stress, and hence, can be deposited onto nearly any substrate material to any thickness. Controlled deposition yields reproducible NPC density, morphology, and porosity, without any discernable variation in surface chemistry. NPC coatings > 20 {micro}m thick with density < 5% that of graphite have been demonstrated. NPC can be 'doped' with nearly any metal during growth to provide further enhancements in analyte detection and selectivity. Optimized NPC-coated SAW devices were compared directly to commonly-used polymer coated SAWs for sensitivity to a variety of VOC, TIC, CWA and NPP. In every analyte, NPC outperforms each polymer coating by multiple orders-of-magnitude in detection sensitivity, with improvements ranging from 103 to 108 times greater detection sensitivity! NPC-coated SAW sensors appear capable of detecting most analytes

  16. A case of multivariate Birkhoff interpolation using high order derivatives

    OpenAIRE

    Goldman, Gil

    2016-01-01

    We consider a specific scheme of multivariate Birkhoff polynomial interpolation. Our samples are derivatives of various orders $k_j$ at fixed points $v_j$ along fixed straight lines through $v_j$ in directions $u_j$, under the following assumption: the total number of sampled derivatives of order $k, \\ k=0,1,\\ldots$ is equal to the dimension of the space homogeneous polynomials of degree $k$. We show that this scheme is regular for general directions. Specifically this scheme is regular indep...

  17. A 150 nm ultraviolet excitation volume on a porous silicon membrane for direct optical observation of DNA coil relaxation during capture into nanopores

    Science.gov (United States)

    Yamazaki, Hirohito; Esashika, Keiko; Saiki, Toshiharu

    2017-06-01

    We report the first optical observation of DNA coil relaxation during capture into silicon nanopores, which was achieved using fluorescence microscopy with a 150 nm observation volume. Compared with our previous results, the gradual increase and steep decay of the fluorescence signal can be interpreted as the capture of the DNA molecule and its translocation through the nanopore, respectively. Furthermore, a longer dwell time was obtained when we used a nanoporous membrane with high porosity. From a numerical calculation of the electric field distribution in the vicinity of the nanopore, we concluded that a ‘biased’ electric field, as well as funneling of the field into surrounding nanopores, hinders DNA coil relaxation. Our result showed the capability of a UV excitation volume on a silicon membrane for observation of DNA capture into nanopores at a single-molecule level.

  18. Atomically resolved imaging of highly ordered alternating fluorinated graphene

    Science.gov (United States)

    Kashtiban, Reza J.; Dyson, M. Adam; Nair, Rahul R.; Zan, Recep; Wong, Swee L.; Ramasse, Quentin; Geim, Andre K.; Bangert, Ursel; Sloan, Jeremy

    2014-09-01

    One of the most desirable goals of graphene research is to produce ordered two-dimensional (2D) chemical derivatives of suitable quality for monolayer device fabrication. Here we reveal, by focal series exit wave reconstruction (EWR), that C2F chair is a stable graphene derivative and demonstrates pristine long-range order limited only by the size of a functionalized domain. Focal series of images of graphene and C2F chair formed by reaction with XeF2 were obtained at 80 kV in an aberration-corrected transmission electron microscope. EWR images reveal that single carbon atoms and carbon-fluorine pairs in C2F chair alternate strictly over domain sizes of at least 150 nm2 with electron diffraction indicating ordered domains ≥0.16 μm2. Our results also indicate that, within an ordered domain, functionalization occurs on one side only as theory predicts. In addition, we show that electron diffraction provides a quick and easy method for distinguishing between graphene, C2F chair and fully fluorinated stoichiometric CF 2D phases.

  19. High-order noise filtering in nontrivial quantum logic gates

    CSIR Research Space (South Africa)

    Green, T

    2012-07-01

    Full Text Available that must be accounted for in order to understand total average error rates. We develop a treatment based on effective Hamiltonian theory that allows us to efficiently model the effect of classical noise on nontrivial single-bit quantum logic operations...

  20. Dual-Mode Nanoporous Copper by Dealloying Al-Cu-Nacl Bulk Alloys and Its High Degradation Efficiency Toward Methyl Orange

    Science.gov (United States)

    Yu, Nana; Jiang, Lianyu; Hou, Hongyan; Chen, Xiutong; Li, Jie; Geng, Haoran; Zhao, Degang

    2017-03-01

    In this work, a facile synthesis route was applied to fabricate nanoporous copper (NPC). As-sintered AlCu bulk alloys with (or without) NaCl that were fabricated by powder metallurgy were taken as precursors during the preparation of NPC via chemical dealloying. The effects of NaCl in the alloys on precursors and products were investigated. Scanning electron microscope (SEM) examinations showed that the addition of NaCl is really beneficial to the formation of a dual-mode pore structure. The x-ray diffraction (XRD) revealed that the AlCu phase formed at the powder metallurgy stage could be completely corroded in HCl solution in the as-dealloyed products, whereas it remains unchanged in the NaOH condition. SEM images showed that NPC was characterized by a three-dimensional, bicontinuous, uniform, or dual-mode ligament-channel structure with nanoscale length. There were no obvious AlCu blocks or other bulks in the NPC sample fabricated from Al67Cu33 alloys with NaCl. In addition, it exhibited hierarchical structures with two distinctive pore sizes, which results in the best photocatalytic properties of NPC. Moreover, the photocatalytic properties of NPC for methyl orange (MO) degradation in water solution were evaluated, and it miraculously showed enhanced photocatalytic performance of exceeding 99% at even a brief time.

  1. Controlling DNA Translocation Speed through Solid-State Nanopores by Surface Charge Modulation

    Science.gov (United States)

    Meller, Amit

    2013-03-01

    The Nanopore method is an emerging technique, which extends gel-electrophoresis to the single-molecule level and allows the analysis of DNAs, RNAs and DNA-protein complexes. The strength of the technique stems from two fundamental facts: First, nanopores due to their nanoscale size can be used to uncoil biopolymers, such as DNA or RNA and slide them in a single file manner that allows scanning their properties. Consequently, the method can be used to probe short as well as extremely long biopolymers, such as genomic DNA with high efficiency. Second, electrostatic focusing of charged biopolymers into the nanopore overcomes thermally driven diffusion, thus facilitating an extremely efficient end-threading (or capture) of DNA. Thus, nanopores can be used to detect minute DNA copy numbers, circumventing costly molecular amplification such as Polymerase Chain Reaction. A critical factor, which determines the ability of nanopore to distinguish fine properties within biopolymers, such as the location of bound small-molecules, proteins, or even the nucleic acid's sequence, is the speed at which molecules are translocated through the pore. When the translocation speed is too high the electrical noise masks the desired signal, thus limiting the utility of the method. Here I will discuss new experimental results showing that modulating the surface charge inside the pore can effectively reduce the translocation speed through solid-state nanopores fabricated in thin silicon nitride membranes. I will present a simple physical model to account for these results.

  2. Dynamical evolution of space debris on high-elliptical orbits near high-order resonance zones

    Science.gov (United States)

    Kuznetsov, Eduard; Zakharova, Polina

    2015-08-01

    Both analytical and numerical results are used to study high-order resonance regions in the vicinity of Molniya-type orbits. Based on data of numerical simulations, long-term orbital evolution are studied for HEO objects depending on their AMR. The Poynting-Robertson effect causes a secular decrease in the semi-major axis of a spherically symmetrical satellite. Under the Poynting-Robertson effect, objects pass through the regions of high-order resonances. The Poynting-Robertson effect and secular perturbations of the semi-major axis lead to the formation of weak stochastic trajectories.

  3. Solid-state Nanopore for Detecting Individual Biopolymers

    Science.gov (United States)

    Li, Jiali; Golovchenko, Jene A.

    2011-01-01

    Solid-state nanopores have been fabricated and used to characterize single DNA and protein molecules. Here we describe the details on how these nanopores were fabricated and characterized, the nanopore sensing system setup, and the protocols of using these nanopores to characterize DNA and protein molecules. PMID:19488695

  4. Nanoporous poly(lactide) by olefin metathesis degradation.

    Science.gov (United States)

    Bertrand, Arthur; Hillmyer, Marc A

    2013-07-31

    We describe an approach to ordered nanoporous poly(lactide) that relies on self-assembly of poly(butadiene)-poly(lactide) (PB-PLA) diblock copolymers followed by selective degradation of PB using olefin metathesis. The block copolymers were obtained by a combination of anionic and ring-opening transesterification polymerizations. The molar mass of each block was tailored to target materials with either a lamellar or cylindrical microphase-separated morphology. Orientation of these nanoscale domains was induced in thin films and monolithic samples through solvent annealing and mechanical deformation, respectively. Selective degradation of PB was achieved by immersing the samples in a solution of Grubbs first-generation catalyst in cyclohexane, a nonsolvent for PLA. Successful elimination of PB was confirmed by size-exclusion chromatography and (1)H NMR spectroscopy. Direct imaging of the resulting nanoporous PLA was obtained by scanning electron microscopy.

  5. Nanoporous functional organosilicas for sorption of toxic ions

    Science.gov (United States)

    Belyakova, L. A.; Lyashenko, D. Yu.

    2014-03-01

    The chemical immobilization of β-cyclodextrin and its bromoacetyl and thiosemicarbazidoacetyl functional derivatives on the surface of highly disperse amorphous nanoporous silica was performed. β-Cyclodextrin-containing silicas were found to have high affinity to mercury(II), cadmium(II), and zinc(II) cations. Supramolecular surface structures formed whose chemical composition depends on the nature of the sorbed cations and the functional substituents in the attached β-cyclodextrin molecules.

  6. Nanoporous Polymer-Ceramic Composite Electrolytes for Lithium Metal Batteries

    KAUST Repository

    Tu, Zhengyuan

    2013-09-16

    A nanoporous composite material that offers the unique combination of high room-temperature ionic conductivity and high mechanical modulus is reported. When used as the separator/electrolyte in lithium batteries employing metallic lithium as anode, the material displays unprecedented cycling stability and excellent ability to prevent premature cell failure by dendrite-induced short circuits © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Nanopore sensors : From hybrid to abiotic systems

    NARCIS (Netherlands)

    Kocer, Armagan; Tauk, Lara; Dejardin, Philippe

    2012-01-01

    The use of nanopores of well controlled geometry for sensing molecules in solution is reviewed. Focus is concentrated especially on synthetic track-etch pores in polymer foils and on biological nanopores, i.e. ion channels. After a brief section about multipore sensors, specific attention is

  8. UV Defined Nanoporous Liquid Core Waveguides

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Gopalakrishnan, Nimi; Ndoni, Sokol

    2011-01-01

    Nanoporous liquid core waveguides, where both core and cladding are made from the same material, are presented. The nanoporous polymer used is intrinsically hydrophobic, but selective UV exposure enables it to infiltrate with an aqueous solution, thus raising the refractive index from 1.26 to 1...

  9. Actuating and Sensing Properties of Nanoporous Gold

    NARCIS (Netherlands)

    Detsi, E.; Chen, Z. G.; Vellinga, W. P.; Onck, P. R.; De Hosson, J. T. M.

    We show that variations in the relative humidity give rise to reversible macroscopic dimensional changes in nanoporous gold exposed to ambient air. The macroscopic strain is the consequence of changes in the nanoporous gold surface stress. We have measured reversible strain amplitudes up to 0.02% in

  10. Performance of Several High Order Numerical Methods for Supersonic Combustion

    Science.gov (United States)

    Sjoegreen, Bjoern; Yee, H. C.; Don, Wai Sun; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    The performance of two recently developed numerical methods by Yee et al. and Sjoegreen and Yee using postprocessing nonlinear filters is examined for a 2-D multiscale viscous supersonic react-live flow. These nonlinear filters can improve nonlinear instabilities and at the same time can capture shock/shear waves accurately. They do not, belong to the class of TVD, ENO or WENO schemes. Nevertheless, they combine stable behavior at discontinuities and detonation without smearing the smooth parts of the flow field. For the present study, we employ a fourth-order Runge-Kutta in time and a sixth-order non-dissipative spatial base scheme for the convection and viscous terms. We denote the resulting nonlinear filter schemes ACM466-RK4 and WAV66-RK4.

  11. New high order FDTD method to solve EMC problems

    Directory of Open Access Journals (Sweden)

    N. Deymier

    2015-10-01

    Full Text Available In electromagnetic compatibility (EMC context, we are interested in developing new ac- curate methods to solve efficiently and accurately Maxwell’s equations in the time domain. Indeed, usual methods such as FDTD or FVTD present im- portant dissipative and/or dispersive errors which prevent to obtain a good numerical approximation of the physical solution for a given industrial scene unless we use a mesh with a very small cell size. To avoid this problem, schemes like the Discontinuous Galerkin (DG method, based on higher order spa- tial approximations, have been introduced and stud- ied on unstructured meshes. However the cost of this kind of method can become prohibitive accord- ing to the mesh used. In this paper, we first present a higher order spatial approximation method on carte- sian meshes. It is based on a finite element ap- proach and recovers at the order 1 the well-known Yee’s schema. Next, to deal with EMC problem, a non-oriented thin wire formalism is proposed for this method. Finally, several examples are given to present the benefits of this new method by compar- ison with both Yee’s schema and DG approaches.

  12. Nanoporous metals for advanced energy technologies

    CERN Document Server

    Ding, Yi

    2016-01-01

    This book covers the state-of-the-art research in nanoporous metals for potential applications in advanced energy fields, including proton exchange membrane fuel cells, Li batteries (Li ion, Li-S, and Li-O2), and supercapacitors. The related structural design and performance of nanoporous metals as well as possible mechanisms and challenges are fully addressed. The formation mechanisms of nanoporous metals during dealloying, the microstructures of nanoporous metals and characterization methods, as well as miscrostructural regulation of nanoporous metals through alloy design of precursors and surface diffusion control are also covered in detail. This is an ideal book for researchers, engineers, graduate students, and government/industry officers who are in charge of R&D investments and strategy related to energy technologies.

  13. Recent progress in molecular simulation of nanoporous graphene membranes for gas separation

    Science.gov (United States)

    Fatemi, S. Mahmood; Baniasadi, Aminreza; Moradi, Mahrokh

    2017-07-01

    If an ideal membrane for gas separation is to be obtained, the following three characteristics should be considered: the membrane should be as thin as possible, be mechanically robust, and have welldefined pore sizes. These features will maximize its solvent flux, preserve it from fracture, and guarantee its selectivity. Graphene is made up of a hexagonal honeycomb lattice of carbon atoms with sp 2 hybridization state forming a one-atom-thick sheet of graphite. Following conversion of the honeycomb lattices into nanopores with a specific geometry and size, a nanoporous graphene membrane that offers high efficiency as a separation membrane because of the ultrafast molecular permeation rate as a result of its one-atom thickness is obtained. Applications of nanoporous graphene membranes for gas separation have been receiving remarkably increasing attention because nanoporous graphene membranes show promising results in this area. This review focuses on the recent advances in nanoporous graphene membranes for applications in gas separation, with a major emphasis on theoretical works. The attractive properties of nanoporous graphene membranes introduce make them appropriate candidates for gas separation and gas molecular-sieving processes in nanoscale dimensions.

  14. Hydrogen Peroxide Sensing Based on Inner Surfaces Modification of Solid-State Nanopore

    Science.gov (United States)

    Zhu, Libo; Gu, Dejian; Liu, Quanjun

    2017-06-01

    There are many techniques for the detection of molecules. But detection of molecules through solid-state nanopore in a solution is one of the promising, high-throughput, and low-cost technology used these days. In the present investigation, a solid-state nanopore platform was fabricated for the detection of hydrogen peroxide (H2O2), which is not only a label free product but also a significant participant in the redox reaction. We have successfully fabricated silicon nitride (Si3N4) nanopores with diameters of 50 nm by using a focused Ga ion beam, the inner surface of the nanopore has been modified with horseradish peroxidase (HRP) by employing carbodiimide coupling chemistry. The immobilized HRP enzymes have ability to induce redox reactions in a single nanopore channel. Moreover, a real-time single aggregated ABTS•+ molecular translocation events were monitored and investigated. The designed solid-state nanopore biosensor is reversible and can be applied to detect H2O2 multiple times.

  15. Improving the performance of water desalination through ultra-permeable functionalized nanoporous graphene oxide membrane

    Science.gov (United States)

    Hosseini, Mostafa; Azamat, Jafar; Erfan-Niya, Hamid

    2018-01-01

    Molecular dynamics simulations were performed to investigate the water desalination performance of nanoporous graphene oxide (NPGO) membranes. The simulated systems consist of a NPGO as a membrane with a functionalized pore in its center immersed in an aqueous ionic solution and a graphene sheet as a barrier. The considered NPGO membranes are involved four types of pore with different size and chemistry. The results indicated that the NPGO membrane has effective efficiency in salt rejection as well as high performance in water flux. For all types of pore with the radius size of 2.9-4.5 Å, the NPGO shows salt rejection of >89%. Functional groups on the surface and edge of pores have a great effect on water flux. To precisely understand the effect of functional groups on the surface of nanostructured membranes, nanoporous graphene was simulated under the same condition for comparison. Hydrophilic groups on the surface make the NPGO as an ultra-permeable membrane. As a result, the obtained water flux for NPGO was about 77% greater than graphene. Also, it was found that the water flux of NPGO is 2-5 orders of magnitude greater than other existing reverse osmosis membranes. Therefore, the investigated systems can be recommended as a model for the water desalination.

  16. Nanoporous Films with Sub-10 nm in Pore Size from Acid-Cleavable Block Copolymers.

    Science.gov (United States)

    Li, Yayuan; Xu, Yawei; Cao, Shubo; Zhao, Yongbin; Qu, Ting; Iyoda, Tomokazu; Chen, Aihua

    2017-03-01

    Nanoporous thin films with pore size of sub-10 nm are fabricated using an acid-cleavable block copolymer (BCP), a benzoic imine junction between poly(ethylene oxide) (PEO) and poly(methacrylate) (PMAAz) bearing an azobenzene side chain (denoted as PEO-bei-PMAAz) as the precursor. After a thermal annealing, the block copolymers are self-assembled to form highly ordered PEO cylinders within a PMAAz matrix normal to the film, even in the case of low BCP molecular weight due to the existing of the liquid crystalline (LC) azobenzene rigid segment. Thus, PMAAz thin films with pore size of ≈7 nm and density of ≈10(12) cm(-2) are obtained after removal of the PEO minor phase by breaking the benzoic imine junction under mild acidic conditions. This work enriches the nanoporous polymer films from BCP precursors and introduces the LC property as a functionality which can further enhance the mechanical properties of the films and broaden their applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. High-Order Entropy Stable Formulations for Computational Fluid Dynamics

    Science.gov (United States)

    Carpenter, Mark H.; Fisher, Travis C.

    2013-01-01

    A systematic approach is presented for developing entropy stable (SS) formulations of any order for the Navier-Stokes equations. These SS formulations discretely conserve mass, momentum, energy and satisfy a mathematical entropy inequality. They are valid for smooth as well as discontinuous flows provided sufficient dissipation is added at shocks and discontinuities. Entropy stable formulations exist for all diagonal norm, summation-by-parts (SBP) operators, including all centered finite-difference operators, Legendre collocation finite-element operators, and certain finite-volume operators. Examples are presented using various entropy stable formulations that demonstrate the current state-of-the-art of these schemes.

  18. Nonlinear diffraction from high-order Hermite-Gauss beams.

    Science.gov (United States)

    Kalinowski, Ksawery; Shapira, Asia; Libster-Hershko, Ana; Arie, Ady

    2015-01-01

    We investigate experimentally and theoretically the nonlinearly diffracted second harmonic light from the first-order Hermite-Gauss beam. We investigate the cases of loosely and tightly focused beams in a periodically poled lithium niobate crystal in the temperature range near the birefringent phase matching. Unlike the case of fundamental Gaussian beam, the nonlinear diffracted beam is spatially structured. Its shape depends on the focusing conditions and on the crystal temperature. Furthermore, for the case of tight focusing, the diffracted beam structure depends on the beam's position with respect to the domain wall.

  19. High resolution study of magnetic ordering at absolute zero.

    Science.gov (United States)

    Lee, M; Husmann, A; Rosenbaum, T F; Aeppli, G

    2004-05-07

    High resolution pressure measurements in the zero-temperature limit provide a unique opportunity to study the behavior of strongly interacting, itinerant electrons with coupled spin and charge degrees of freedom. Approaching the precision that has become the hallmark of experiments on classical critical phenomena, we characterize the quantum critical behavior of the model, elemental antiferromagnet chromium, lightly doped with vanadium. We resolve the sharp doubling of the Hall coefficient at the quantum critical point and trace the dominating effects of quantum fluctuations up to surprisingly high temperatures.

  20. High order fluid model for ionization fronts in streamer discharges

    NARCIS (Netherlands)

    A. Markosyan (Aram); S. Dujko (Sasa); W. Hundsdorfer (Willem); U. Ebert (Ute)

    2011-01-01

    htmlabstractWhen non-ionized or lowly ionized matter is exposed to high electric fields, non-equilibrium ionization processes, streamer discharges, can develop. Streamers occur in nature and as well in many industrial applications such as the treatment of exhaust gasses, polluted water or biogas. A

  1. Surface Modification of a Nanoporous Carbon Photoanode upon Irradiation

    OpenAIRE

    Gomis Berenguer, Alicia; Velo Gala, Inmaculada; Rodríguez-Castellón, Enrique; Ovín Ania, María Concepción

    2016-01-01

    The photocorrosion of a nanoporous carbon photoanode, with low surface functionalization and high performance towards the photoelectrochemical oxidation of water using simulated solar light, was investigated. Two different light configurations were used to isolate the effect of the irradiation wavelength (UV and visible light) on the textural and chemical features of the carbon photoanode, and its long-term photocatalytic performance for the oxygen evolution reaction. A complete characterizat...

  2. Mathematical modeling and simulation of nanopore blocking by precipitation

    KAUST Repository

    Wolfram, M-T

    2010-10-29

    High surface charges of polymer pore walls and applied electric fields can lead to the formation and subsequent dissolution of precipitates in nanopores. These precipitates block the pore, leading to current fluctuations. We present an extended Poisson-Nernst-Planck system which includes chemical reactions of precipitation and dissolution. We discuss the mathematical modeling and present 2D numerical simulations. © 2010 IOP Publishing Ltd.

  3. Permeation of nanopores by water the effects of channel polarization

    CERN Document Server

    Allen, R; Hansen, J P

    2003-01-01

    Molecular dynamics simulations are used to characterize the permeation by water of cylindrical nanopores, modelling ion channels, as a function of channel radius R and dielectric permittivity epsilon. Intermittent permeation is found in a narrow range around the threshold values of R and epsilon. While channel permeation is highly sensitive to channel polarization effects, no effect on structural properties of the confined water is found on varying epsilon.

  4. Detection of Doppler Microembolic Signals Using High Order Statistics

    Directory of Open Access Journals (Sweden)

    Maroun Geryes

    2016-01-01

    Full Text Available Robust detection of the smallest circulating cerebral microemboli is an efficient way of preventing strokes, which is second cause of mortality worldwide. Transcranial Doppler ultrasound is widely considered the most convenient system for the detection of microemboli. The most common standard detection is achieved through the Doppler energy signal and depends on an empirically set constant threshold. On the other hand, in the past few years, higher order statistics have been an extensive field of research as they represent descriptive statistics that can be used to detect signal outliers. In this study, we propose new types of microembolic detectors based on the windowed calculation of the third moment skewness and fourth moment kurtosis of the energy signal. During energy embolus-free periods the distribution of the energy is not altered and the skewness and kurtosis signals do not exhibit any peak values. In the presence of emboli, the energy distribution is distorted and the skewness and kurtosis signals exhibit peaks, corresponding to the latter emboli. Applied on real signals, the detection of microemboli through the skewness and kurtosis signals outperformed the detection through standard methods. The sensitivities and specificities reached 78% and 91% and 80% and 90% for the skewness and kurtosis detectors, respectively.

  5. Calcium-induced voltage gating in single conical nanopores.

    Science.gov (United States)

    Siwy, Zuzanna S; Powell, Matthew R; Petrov, Alexander; Kalman, Eric; Trautmann, Christina; Eisenberg, Robert S

    2006-08-01

    We examine time signals of ion current through single conically shaped nanopores in the presence of sub-millimolar concentrations of calcium ions. We show that calcium induces voltage-dependent ion current fluctuations in time in addition to the previously reported negative incremental resistance (Nano Lett. 2006, 6, 473-477). These current fluctuations occur on the millisecond time scale at voltages at which the effect of negative incremental resistance was observed. We explain the fluctuations as results of transient binding of calcium ions to carboxyl groups on the pore walls that cause transient changes in electric potential inside a conical nanopore. We support this explanation by recordings of ion current in the presence of manganese ions that bind to carboxyl groups 3 orders of magnitude more tightly than calcium ions. The system of a single conical nanopore with calcium ions is compared to a semiconductor device of a unijunction transistor in electronic circuits. A unijunction transistor also exhibits negative incremental resistance and current instabilities.

  6. High-density quantum sensing with dissipative first order transitions

    OpenAIRE

    Raghunandan, Meghana; Wrachtrup, Jörg; Weimer, Hendrik

    2017-01-01

    The sensing of external fields using quantum systems is a prime example of an emergent quantum technology. Generically, the sensitivity of a quantum sensor consisting of $N$ independent particles is proportional to $\\sqrt{N}$. However, interactions invariably occuring at high densities lead to a breakdown of the assumption of independence between the particles, posing a severe challenge for quantum sensors operating at the nanoscale. Here, we show that interactions in quantum sensors can be t...

  7. Nanoporous Anodic Alumina Platforms: Engineered Surface Chemistry and Structure for Optical Sensing Applications

    Directory of Open Access Journals (Sweden)

    Tushar Kumeria

    2014-07-01

    Full Text Available Electrochemical anodization of pure aluminum enables the growth of highly ordered nanoporous anodic alumina (NAA structures. This has made NAA one of the most popular nanomaterials with applications including molecular separation, catalysis, photonics, optoelectronics, sensing, drug delivery, and template synthesis. Over the past decades, the ability to engineer the structure and surface chemistry of NAA and its optical properties has led to the establishment of distinctive photonic structures that can be explored for developing low-cost, portable, rapid-response and highly sensitive sensing devices in combination with surface plasmon resonance (SPR and reflective interference spectroscopy (RIfS techniques. This review article highlights the recent advances on fabrication, surface modification and structural engineering of NAA and its application and performance as a platform for SPR- and RIfS-based sensing and biosensing devices.

  8. Culture-independent analysis of liver abscess using nanopore sequencing.

    Science.gov (United States)

    Gong, Liang; Huang, Yao-Ting; Wong, Chee-Hong; Chao, Wen-Cheng; Wu, Zong-Yen; Wei, Chia-Lin; Liu, Po-Yu

    2018-01-01

    The identification of microbial species has depended predominantly upon culture-based techniques. However, the difficulty with which types of organisms are cultured implies that the grown species may be overrepresented by both cultivation and plate counts. In recent years, culture-independent analysis using high-throughput sequencing has been advocated for use as a point-of-care diagnostic tool. Although it offers a rapid and unbiased survey to characterize the pathogens in clinical specimens, its accuracy is reduced by the high level of contamination of human DNA. In this paper, we propose using a culture-independent analysis for a Klebsiella pneumoniae clinical strain within a liver abscess using nanopore sequencing. Owing to the highly-contaminated cell population within a liver abscess, we managed to reduce the confounding effects of human DNA through the use of DNase and differential centrifugation. Genomic DNA was sequenced through the use of Nanopore MinION sequencer and analyzed using a suite of bioinformatics approaches. K. pneumoniae was successfully identified along with antibiotic-resistant genes. Our results indicate that, by integrating real-time nanopore sequencing and bioinformatics software, real-time pathogen identification in a liver abscess can be achieved.

  9. High-order adaptive methods for parabolic systems

    Science.gov (United States)

    Adjerid, S.; Flaherty, J. E.; Moore, P. K.; Wang, Y. J.

    1992-11-01

    We consider the adaptive solution of parabolic partial differential systems in one and two space dimensions by finite element procedures that automatically refine and coarsen computational meshes, vary the degree of the piecewise polynomial basis and, in one dimension, move the computational mesh. Two-dimensional meshes of triangular, quadrilateral, or a mixture of triangular and quadrilateral elements are generated using a finite quadtree procedure that is also used for data management. A posteriori estimates, used to control adaptive enrichment, are generated from the hierarchical polynomial basis. Temporal integration, within a method-of-lines framework, uses either backward difference methods or a variant of the singly implicit Runge-Kutta (SIRK) methods. A high-level user interface facilitates use of the adaptive software.

  10. Efficient fabrication of nanoporous si and Si/Ge enabled by a heat scavenger in magnesiothermic reactions

    National Research Council Canada - National Science Library

    Luo, Wei; Wang, Xingfeng; Meyers, Colin; Wannenmacher, Nick; Sirisaksoontorn, Weekit; Lerner, Michael M; Ji, Xiulei

    2013-01-01

    Magnesiothermic reduction can directly convert SiO2 into Si nanostructures. Despite intense efforts, efficient fabrication of highly nanoporous silicon by Mg still remains a significant challenge due to the exothermic reaction nature...

  11. Genomic Pathogen Typing Using Solid-State Nanopores.

    Directory of Open Access Journals (Sweden)

    Allison H Squires

    Full Text Available In clinical settings, rapid and accurate characterization of pathogens is essential for effective treatment of patients; however, subtle genetic changes in pathogens which elude traditional phenotypic typing may confer dangerous pathogenic properties such as toxicity, antibiotic resistance, or virulence. Existing options for molecular typing techniques characterize the critical genomic changes that distinguish harmful and benign strains, yet the well-established approaches, in particular those that rely on electrophoretic separation of nucleic acid fragments on a gel, have room for only incremental future improvements in speed, cost, and complexity. Solid-state nanopores are an emerging class of single-molecule sensors that can electrophoretically characterize charged biopolymers, and which offer significant advantages in terms of sample and reagent requirements, readout speed, parallelization, and automation. We present here the first application of nanopores for single-molecule molecular typing using length based "fingerprints" of critical sites in bacterial genomes. This technique is highly adaptable for detection of different types of genetic variation; as we illustrate using prototypical examples including Mycobacterium tuberculosis and methicillin-resistant Streptococcus aureus, the solid-state nanopore diagnostic platform may be used to detect large insertions or deletions, small insertions or deletions, and even single-nucleotide variations in bacterial DNA. We further show that Bayesian classification of test samples can provide highly confident pathogen typing results based on only a few tens of independent single-molecule events, making this method extremely sensitive and statistically robust.

  12. High-resolution x-ray scattering studies of charge ordering in highly correlated electron systems

    CERN Document Server

    Ghazi, M E

    2002-01-01

    addition, another very weak satellites with wavevector (1/2, 1, 1/2) were observed possibly due to spin ordering. two-dimensional in nature both by measurements of their correlation lengths and by measurement of the critical exponents of the charge stripe melting transition with an anomaly at x = 0.25. The results show by decreasing the hole concentration from the x = 0.33 to 0.2, the well-correlated charge stripes change to a glassy state at x = 0.25. The electronic transition into the charge stripe phase is second-order without any corresponding structural transition. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. In a single-crystal of Nd sub 1 sub / sub 2 Sr sub 1 sub / sub 2 MnO sub 3 a series of phase transitions were observed using high-resolution synchrotron X-ray scattering. Above the charge ordering transition temperature, T sub C sub O , by measuring the peak profiles of Bragg reflections as a function of temperature, it was foun...

  13. Variation in geometry and electrical conductance properties of asymmetric track-etched single nanopores: How uniform are they?

    Energy Technology Data Exchange (ETDEWEB)

    Olejniczak, K., E-mail: kziel@jinr.ru [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation); Faculty of Chemistry, Nicolaus Copernicus University, Gagarina Str. 7, 87-100 Torun (Poland); Orelovich, O.L. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation); Apel, P.Y. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation); Dubna International University, Universitetskaya Str. 19, 141980 Dubna (Russian Federation)

    2015-12-15

    In this paper, the transport property uniformity of single asymmetric pores in polyethylene terephthalate membranes was investigated. Two types of films, Hostaphan RN and Hostaphan RNK, were used. The foils were irradiated with either single or multiple (∼10{sup 8} cm{sup −2}) Au and Xe ions. Samples were UV-treated and etched in surfactant-doped 5 mol/L NaOH at 60 °C for 6 min and 30 s in order to obtain nanopores with bullet-shaped tips. The geometry of the nanopores was determined from SEM images of multi-pore membrane cross sections. The reproducibility of the electrical characteristics of individual nanopores with bullet-like tips in two different types of polyethylene terephthalate foils was studied. The relationship between electro-conductive properties of the asymmetric nanopores and the polymer morphology is discussed.

  14. Fabrication of nanoporous graphene/polymer composite membranes.

    Science.gov (United States)

    Madauß, Lukas; Schumacher, Jens; Ghosh, Mandakranta; Ochedowski, Oliver; Meyer, Jens; Lebius, Henning; Ban-d'Etat, Brigitte; Toimil-Molares, Maria Eugenia; Trautmann, Christina; Lammertink, Rob G H; Ulbricht, Mathias; Schleberger, Marika

    2017-07-27

    Graphene is currently investigated as a promising membrane material in which selective pores can be created depending on the requirements of the application. However, to handle large-area nanoporous graphene a stable support material is needed. Here, we report on composite membranes consisting of large-area single layer nanoporous graphene supported by a porous polymer. The fabrication is based on ion-track nanotechnology with swift heavy ions directly creating atomic pores in the graphene lattice and damaged tracks in the polymer support. Subsequent chemical etching converts the latent ion tracks in the supporting polymer foil, here polyethylene terephthalate (PET), into open microchannels while the perfectly aligned pores in the graphene top layer remain unaffected. To avoid unintentional damage creation and delamination of the graphene layer from the substrate, the graphene is encapsulated by a protecting poly(methyl methacrylate) (PMMA) layer. By this procedure a stable composite membrane is obtained consisting of nanoporous graphene (coverage close to 100%) suspended across selfaligned track-etched microchannels in a polymer support film. Our method presents a facile way to create high quality suspended graphene of tunable pore size supported on a flexible porous polymeric support, thus enabling the development of membranes for fast and selective ultrafiltration separation processes.

  15. Functional Nanomaterials based on Nanoporous Block Copolymer Templates

    Science.gov (United States)

    Kim, Jin Kon

    2011-03-01

    Nanoporous templates have been widely used for the development of new functional nanostructured materials suitable for electronics, optics, magnetism, and energy storage materials. We have prepared nanoporous templates by using thin films of mixtures of polystyrene-block-poly(methyl methacrylate) (PS- b -PMMA) and PMMA homopolymers. These nanoporous films were found to be very effective for the separation of human Rhinovirus type 14, major pathogen of a common cold in humans. We found that when the pore size was effectively controlled down to 6 nm, a long-term constant in vitro release of BSA and hGH was achieved without their denaturation up to 2 months. The long-term constant delivery based on this membrane for protein drugs within the therapeutic range can be highly appreciated for the patients with hormone-deficiency. Work done in collaboration with Seung Yun Yang, Pohang University of Science and Technology. This work was supported by the National Creative Research Initiative Program supported by NRF.

  16. Plasmonic Nanopores for Trapping, Controlling Displacement, and Sequencing of DNA.

    Science.gov (United States)

    Belkin, Maxim; Chao, Shu-Han; Jonsson, Magnus P; Dekker, Cees; Aksimentiev, Aleksei

    2015-11-24

    With the aim of developing a DNA sequencing methodology, we theoretically examine the feasibility of using nanoplasmonics to control the translocation of a DNA molecule through a solid-state nanopore and to read off sequence information using surface-enhanced Raman spectroscopy. Using molecular dynamics simulations, we show that high-intensity optical hot spots produced by a metallic nanostructure can arrest DNA translocation through a solid-state nanopore, thus providing a physical knob for controlling the DNA speed. Switching the plasmonic field on and off can displace the DNA molecule in discrete steps, sequentially exposing neighboring fragments of a DNA molecule to the pore as well as to the plasmonic hot spot. Surface-enhanced Raman scattering from the exposed DNA fragments contains information about their nucleotide composition, possibly allowing the identification of the nucleotide sequence of a DNA molecule transported through the hot spot. The principles of plasmonic nanopore sequencing can be extended to detection of DNA modifications and RNA characterization.

  17. Oxford Nanopore MinION Sequencing and Genome Assembly

    Directory of Open Access Journals (Sweden)

    Hengyun Lu

    2016-10-01

    Full Text Available The revolution of genome sequencing is continuing after the successful second-generation sequencing (SGS technology. The third-generation sequencing (TGS technology, led by Pacific Biosciences (PacBio, is progressing rapidly, moving from a technology once only capable of providing data for small genome analysis, or for performing targeted screening, to one that promises high quality de novo assembly and structural variation detection for human-sized genomes. In 2014, the MinION, the first commercial sequencer using nanopore technology, was released by Oxford Nanopore Technologies (ONT. MinION identifies DNA bases by measuring the changes in electrical conductivity generated as DNA strands pass through a biological pore. Its portability, affordability, and speed in data production makes it suitable for real-time applications, the release of the long read sequencer MinION has thus generated much excitement and interest in the genomics community. While de novo genome assemblies can be cheaply produced from SGS data, assembly continuity is often relatively poor, due to the limited ability of short reads to handle long repeats. Assembly quality can be greatly improved by using TGS long reads, since repetitive regions can be easily expanded into using longer sequencing lengths, despite having higher error rates at the base level. The potential of nanopore sequencing has been demonstrated by various studies in genome surveillance at locations where rapid and reliable sequencing is needed, but where resources are limited.

  18. Plasmonic Nanopores for Trapping, Controlling Displacement, and Sequencing of DNA

    Science.gov (United States)

    2015-01-01

    With the aim of developing a DNA sequencing methodology, we theoretically examine the feasibility of using nanoplasmonics to control the translocation of a DNA molecule through a solid-state nanopore and to read off sequence information using surface-enhanced Raman spectroscopy. Using molecular dynamics simulations, we show that high-intensity optical hot spots produced by a metallic nanostructure can arrest DNA translocation through a solid-state nanopore, thus providing a physical knob for controlling the DNA speed. Switching the plasmonic field on and off can displace the DNA molecule in discrete steps, sequentially exposing neighboring fragments of a DNA molecule to the pore as well as to the plasmonic hot spot. Surface-enhanced Raman scattering from the exposed DNA fragments contains information about their nucleotide composition, possibly allowing the identification of the nucleotide sequence of a DNA molecule transported through the hot spot. The principles of plasmonic nanopore sequencing can be extended to detection of DNA modifications and RNA characterization. PMID:26401685

  19. Nanoporous PdCo Catalyst for Microfuel Cells: Electrodeposition and Dealloying

    Directory of Open Access Journals (Sweden)

    Satoshi Tominaka

    2011-01-01

    Full Text Available PdCo alloy is a promising catalyst for oxygen reduction reaction of direct methanol fuel cells because of its high activity and the tolerance to methanol. We have applied this catalyst in order to realize on-chip fuel cell which is a membraneless design. The novel design made the fuel cells to be flexible and integratable with other microdevices. Here, we summarize our recent research on the synthesis of nanostructured PdCo catalyst by electrochemical methods, which enable us to deposit the alloy onto microelectrodes of the on-chip fuel cells. First, the electrodeposition of PdCo is discussed in detail, and then, dealloying for introducing nanopores into the electrodeposits is described. Finally, electrochemical response and activities are fully discussed.

  20. Synthesis of single-crystal-like nanoporous carbon membranes and their application in overall water splitting

    KAUST Repository

    Wang, Hong

    2017-01-04

    Nanoporous graphitic carbon membranes with defined chemical composition and pore architecture are novel nanomaterials that are actively pursued. Compared with easy-to-make porous carbon powders that dominate the porous carbon research and applications in energy generation/conversion and environmental remediation, porous carbon membranes are synthetically more challenging though rather appealing from an application perspective due to their structural integrity, interconnectivity and purity. Here we report a simple bottom–up approach to fabricate large-size, freestanding and porous carbon membranes that feature an unusual single-crystal-like graphitic order and hierarchical pore architecture plus favourable nitrogen doping. When loaded with cobalt nanoparticles, such carbon membranes serve as high-performance carbon-based non-noble metal electrocatalyst for overall water splitting.

  1. STUDY OF SAMPLE AND HOLD DIGITAL-ANALOG CONVERTER WITH HIGH ORDER JITTER NOISE SHAPING

    OpenAIRE

    北原, 義大; KITAHARA, Yoshihiro

    2014-01-01

    In this paper, present sample hold DAC with high order jitter noise shaping using 2nd order architecture or feed-forward 2nd order architecture. Performance improvements of sample hold DAC can be expected by using higher order jitter noise shaping. The effectiveness of presented architecture is confirmed by MATLAB simulation results and SPICE simulation results.

  2. Nanofluidic Pathways for Single Molecule Translocation and Sequencing -- Nanotubes and Nanopores

    Science.gov (United States)

    Song, Weisi

    Driven by the curiosity for the secret of life, the effort on sequencing of DNAs and other large biopolymers has never been respited. Advanced from recent sequencing techniques, nanotube and nanopore based sequencing has been attracting much attention. This thesis focuses on the study of first and crucial compartment of the third generation sequencing technique, the capture and translocation of biopolymers, and discuss the advantages and obstacles of two different nanofluidic pathways, nanotubes and nanopores for single molecule capturing and translocation. Carbon nanotubes with its constrained structure, the frictionless inner wall and strong electroosmotic flow, are promising materials for linearly threading DNA and other biopolymers for sequencing. Solid state nanopore on the other hand, is a robust chemical, thermal and mechanical stable nanofluidic device, which has a high capturing rate and, to some extent, good controllable threading ability for DNA and other biomolecules. These two different but similar nanofluidic pathways both provide a good preparation of analyte molecules for the sequencing purpose. In addition, more and more research interests have move onto peptide chains and protein sensing. For proteome is better and more direct indicators for human health, peptide chains and protein sensing have a much wider range of applications on bio-medicine, disease early diagnoses, and etc. A universal peptide chain nanopore sensing technique with universal chemical modification of peptides is discussed in this thesis as well, which unifies the nanopore capturing process for vast varieties of peptides. Obstacles of these nanofluidic pathways are also discussed. In the end of this thesis, a proposal of integration of solid state nanopore and fixed-gap recognition tunneling sequencing technique for a more accurate DNA and peptide readout is discussed, together with some early study work, which gives a new direction for nanopore based sequencing.

  3. Improved Catalysts for Heavy Oil Upgrading Based on Zeolite Y Nanoparticles Encapsulated Stable Nanoporous Host

    Energy Technology Data Exchange (ETDEWEB)

    Conrad Ingram; Mark Mitchell

    2007-09-30

    The objective of this project is to synthesize nanocrystals of highly acidic zeolite Y nanoclusters, encapsulate them within the channels of mesoporous (nanoporous) silicates or nanoporous organosilicates, and evaluate the 'zeolite Y/Nanoporous host' composites as catalysts for the upgrading of heavy petroleum feedstocks. In comparison to conventionally-used zeolite Y catalysts of micron size particles, the nanocrystals (< 100 nm particle size) which contain shorter path lengths, are expected to allow faster diffusion of large hydrocarbon substrates and the catalysis products within and out of the zeolite's channels and cages (<1 nm size). This is expected to significantly reduce deactivation of the catalyst and to prolong their period of reactivity. Encapsulating zeolite Y nanocrystals within the nanoporous materials is expected to protect its external surfaces and pore entrances from being blocked by large hydrocarbon substrates, since these substrates will initially be converted to small molecules by the nanoporous host (a catalyst in its own right). The project consisted of four major tasks as follows: (1) synthesis of the nanoparticles of zeolite Y (of various chemical compositions) using various techniques such as the addition of organic additives to conventional zeolite Y synthesis mixtures to suppress zeolite Y crystal growth; (2) synthesis of nanoporous silicate host materials of up to 30 nm pore diameter, using poly (alkylene oxide) copolymers which when removed will yield a mesoporous material; (3) synthesis of zeolite Y/Nanoporous Host composite materials as potential catalysts; and (4) evaluation of the catalyst for the upgrading of heavy petroleum feedstocks.

  4. A Systematic Approach to Design High-Order Phase-Locked Loops

    DEFF Research Database (Denmark)

    Golestan, Saeed; Fernandez, Francisco Daniel Freijedo; Guerrero, Josep M.

    2015-01-01

    A basic approach to improve the performance of phase-locked loop (PLL) under adverse grid condition is to incorporate a first-order low-pass filter (LPF) into its control loop. The first-order LPF, however, has a limited ability to suppress grid disturbances. A natural thought to further improve...... the disturbance rejection capability of PLL is to use high order LPFs, resulting in high order PLLs. Application of high order LPFs, however, results in high order PLLs, which rather complicates the PLL analysis and design procedure. To overcome this challenge, a systematic method to design high order PLLs...... is presented in this letter. The suggested approach has a general theme, which means it can be applied to design the PLL control parameters regardless of the order of in-loop LPF. The effectiveness of suggested design method is confirmed through different design cases....

  5. Electrically controlled nanoparticle synthesis inside nanopores.

    Science.gov (United States)

    Venta, Kimberly; Wanunu, Meni; Drndić, Marija

    2013-02-13

    From their realization just over a decade ago, nanopores in silicon nitride membranes have allowed numerous transport-based single-molecule measurements. Here we report the use of these nanopores as subzeptoliter mixing volumes for the controlled synthesis of metal nanoparticles. Particle synthesis is controlled and monitored through an electric field applied across the nanopore membrane, which is positioned so as to separate electrolyte solutions of a metal precursor and a reducing agent. When the electric field drives reactive ions to the nanopore, a characteristic drop in the ion current is observed, indicating the formation of a nanoparticle inside the nanopore. While traditional chemical synthesis relies on temperature and timing to monitor particle growth, here we observe it in real time by monitoring electrical current. We describe the dynamics of gold particle formation in sub-10 nm diameter silicon nitride pores and the effects of salt concentration and additives on the particle's shape and size. The current versus time signal during particle formation in the nanopore is in excellent agreement with the Richards growth curve, indicating an access-limited growth mechanism.

  6. Reduced-order LPV model of flexible wind turbines from high fidelity aeroelastic codes

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Sønderby, Ivan Bergquist; Hansen, Morten Hartvig

    2013-01-01

    Linear aeroelastic models used for stability analysis of wind turbines are commonly of very high order. These high-order models are generally not suitable for control analysis and synthesis. This paper presents a methodology to obtain a reduced-order linear parameter varying (LPV) model from a se...

  7. High-resolution nanosphere lithography (NSL) to fabricate highly-ordered ZnO nanorod arrays.

    Science.gov (United States)

    Zhang, Xiaoxian; Zhang, Lihuan; Gao, Min; Zhou, Weiya; Xie, Sishen

    2010-11-01

    Here we report our successful development of a high-resolution, low-cost, simple and convenient technique based on nanosphere lithography (NSL) to fabricate large-scale periodic gold nanoparticle pattern, which is the most common catalyst material in the synthesis of nanostructure and also a feature material for surface plasmon resonation (SPR) research. In order to improve lithography resolution by PS nanosphere self-assembling monolayer (SAM), we adapted the following steps in our fabrication strategy. The original continuous etching by oxygen plasma was replaced by multiple short treatments to avoid heating effect. In addition, direct oxidation was utilized to remove the nanospheres instead of the supersonic process. Using the obtained Au nanoparticle pattern, ZnO nanorod arrays with an average diameter of 50 nm were easily obtained by 600 nm PS nanospheres SAM, which was even smaller than the minimum size by utilizing 400 nm nanospheres SAM in the previous work. Thus, we succeeded in the fabrication of highly-ordered ZnO nanorod arrays with largely tunable diameter by this higher-resolution nanosphere lithography. We also present X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) and Raman results of our as-grown samples, indicating great crystallization quality and optical property.

  8. Nanopore extended field-effect transistor for selective single-molecule biosensing.

    Science.gov (United States)

    Ren, Ren; Zhang, Yanjun; Nadappuram, Binoy Paulose; Akpinar, Bernice; Klenerman, David; Ivanov, Aleksandar P; Edel, Joshua B; Korchev, Yuri

    2017-09-19

    There has been a significant drive to deliver nanotechnological solutions to biosensing, yet there remains an unmet need in the development of biosensors that are affordable, integrated, fast, capable of multiplexed detection, and offer high selectivity for trace analyte detection in biological fluids. Herein, some of these challenges are addressed by designing a new class of nanoscale sensors dubbed nanopore extended field-effect transistor (nexFET) that combine the advantages of nanopore single-molecule sensing, field-effect transistors, and recognition chemistry. We report on a polypyrrole functionalized nexFET, with controllable gate voltage that can be used to switch on/off, and slow down single-molecule DNA transport through a nanopore. This strategy enables higher molecular throughput, enhanced signal-to-noise, and even heightened selectivity via functionalization with an embedded receptor. This is shown for selective sensing of an anti-insulin antibody in the presence of its IgG isotype.Efficient detection of single molecules is vital to many biosensing technologies, which require analytical platforms with high selectivity and sensitivity. Ren et al. combine a nanopore sensor and a field-effect transistor, whereby gate voltage mediates DNA and protein transport through the nanopore.

  9. Tunable, Strain-Controlled Nanoporous MoS₂ Filter for Water Desalination.

    Science.gov (United States)

    Li, Weifeng; Yang, Yanmei; Weber, Jeffrey K; Zhang, Gang; Zhou, Ruhong

    2016-02-23

    The deteriorating state of global fresh water resources represents one of the most serious challenges that scientists and policymakers currently face. Desalination technologies, which are designed to extract potable water from the planet's bountiful stores of seawater, could serve to alleviate much of the stress that presently plagues fresh water supplies. In recent decades, desalination methods have improved via water-filtering architectures based on nanoporous graphene filters and artificial membranes integrated with biological water channels. Here, we report the auspicious performance (in simulations) of an alternative nanoporous desalination filter constructed from a MoS2 nanosheet. In striking contrast to graphene-based filters, we find that the "open" and "closed" states of the MoS2 filter can be regulated by the introduction of mechanical strain, yielding a highly tunable nanopore interface. By applying lateral strain to the MoS2 filter in our simulations, we see that the transition point between "open" and "closed" states occurs under tension that induces about 6% cross-sectional expansion in the membrane (6% strain); the open state of the MoS2 filter demonstrates high water transparency and a strong salt filtering capability even under 12% strain. Our results thus demonstrate the promise of a controllable nanoporous MoS2 desalination filter, wherein the morphology and size of the central nanopore can be precisely regulated by tensile strain. These findings support the design and proliferation of tunable nanodevices for filtration and other applications.

  10. A tensegrity driven DNA nanopore.

    Science.gov (United States)

    Mendoza, O; Calmet, P; Alves, I; Lecomte, S; Raoux, M; Cullin, C; Elezgaray, J

    2017-07-13

    Control of transport across membranes, whether natural or synthetic, is fundamental in many biotechnology applications, including sensing and drug release. Mutations of naturally existing protein channels, such as hemolysin, have been explored in the past. More recently, DNA channels with conductivities in the nanosiemens range have been designed. Regulating transport across DNA channels in response to external stimuli remains an important challenge. Previous designs relied on steric hindrance to control the inner diameter of the channel, which resulted in unstable electric signatures. In this paper we introduce a new design to control electric channel conductance of a DNA nanopore. The tensegrity driven mechanism inhibits the flux of small analytes while keeping a tightly controlled ionic transport modulated by the addition of specific DNA sequences. Current signals are clearly defined, with no sign of gating, opening new perspectives in single molecule DNA sensing.

  11. The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

    Science.gov (United States)

    Kant, Krishna; Priest, Craig; Shapter, Joe G.; Losic, Dusan

    2014-01-01

    The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

  12. A Reduced-Order Controller Considering High-Order Modal Information of High-Rise Buildings for AMD Control System with Time-Delay

    Directory of Open Access Journals (Sweden)

    Zuo-Hua Li

    2017-01-01

    Full Text Available Time-delays of control force calculation, data acquisition, and actuator response will degrade the performance of Active Mass Damper (AMD control systems. To reduce the influence, model reduction method is used to deal with the original controlled structure. However, during the procedure, the related hierarchy information of small eigenvalues will be directly discorded. As a result, the reduced-order model ignores the information of high-order mode, which will reduce the design accuracy of an AMD control system. In this paper, a new reduced-order controller based on the improved Balanced Truncation (BT method is designed to reduce the calculation time and to retain the abandoned high-order modal information. It includes high-order natural frequency, damping ratio, and vibration modal information of the original structure. Then, a control gain design method based on Guaranteed Cost Control (GCC algorithm is presented to eliminate the adverse effects of data acquisition and actuator response time-delays in the design process of the reduced-order controller. To verify its effectiveness, the proposed methodology is applied to a numerical example of a ten-storey frame and an experiment of a single-span four-storey steel frame. Both numerical and experimental results demonstrate that the reduced-order controller with GCC algorithm has an excellent control effect; meanwhile it can compensate time-delays effectively.

  13. Extended Galilean transformations for high-order systems in two integrable hierarchies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Dajun; Chen Dengyuan; Hu Liufeng, E-mail: djzhang@staff.shu.edu.cn [Department of Mathematics, Shanghai University, Shanghai 200444 (China)

    2011-04-15

    For some integrable hierarchies, there is no Galilean transformation that keeps a high-order equation in these hierarchies invariant, although the first one or two lower-order members admit Galilean invariance. However, the case might be changed if we redefine a high-order system. The redefined system consists of the considered high-order equation itself and all the lower-order members in their hierarchy, and each member of the hierarchy is numbered by introducing temporal coordinates (t{sub 0}, t{sub 1}, t{sub 2}, ...) to replace the uniform t. For such a redefined high-order system, one may construct an extended Galilean transformation that keeps the system invariant. Two examples, the high-order Burgers system and the Korteweg-de Vries system, are employed for demonstrating our point.

  14. Nanopore biosensors for detection of proteins and nucleic acids

    NARCIS (Netherlands)

    Maglia, Giovanni; Soskine, Mikhael

    2014-01-01

    Described herein are nanopore biosensors based on a modified cytolysin protein. The nanopore biosensors accommodate macromoiecules including proteins and nucleic acids, and may additionally comprise ligands with selective binding properties.

  15. Anti-reflective nanoporous silicon for efficient hydrogen production

    Science.gov (United States)

    Oh, Jihun; Branz, Howard M

    2014-05-20

    Exemplary embodiments are disclosed of anti-reflective nanoporous silicon for efficient hydrogen production by photoelectrolysis of water. A nanoporous black Si is disclosed as an efficient photocathode for H.sub.2 production from water splitting half-reaction.

  16. Nanoporous Au-Ag shell with fast kinetics: integrating chemical and plasmonic catalysis

    Science.gov (United States)

    Yang, Wenpeng; Wu, Ke; Yang, Weimin; Wang, Hailing; Lv, Xianglong; Qian, Lihua; Yu, Tianshui; Li, Zengquan; Zhou, Xiangji; Okumu Barasa, Godfrey; Yuan, Songliu; Jiang, Yingtao; Yang, Zhilin

    2017-10-01

    Nanoporous noble metals and alloys are widely utilized as efficient catalysts, because they have high surface-to-volume ratios for sufficient active sites and induce molecule polarization through plasmon excitation as well. Herein, we demonstrate one approach to fabricate nanoporous Au-Ag shell. Such material represents the dual functions serving as efficient catalysts and high-performance surface-enhanced Raman scattering substrate. In situ spectrum acquisition can track the conversion of p-nitrothiophenol to 4, 4‧-dimercapto-azobenzene at ambient temperature. In particular, as a result of chemical catalysis of Ag elements and strong plasmon-molecule coupling, catalytic kinetics of nanoporous Au-Ag shell is 79.2-123.8 times faster than Au nanoparticles (NPs), and 2.2-3.3 times faster than Ag NPs. This investigation offers a route to design superior catalysts to integrate chemical and plasmonic catalysis.

  17. Enhancing the platinum atomic layer deposition infiltration depth inside anodic alumina nanoporous membrane

    Energy Technology Data Exchange (ETDEWEB)

    Vaish, Amit, E-mail: anv@udel.edu; Krueger, Susan; Dimitriou, Michael; Majkrzak, Charles [National Institute of Standards and Technology (NIST) Center for Neutron Research, Gaithersburg, MD 20899-8313 (United States); Vanderah, David J. [Institute for Bioscience and Biotechnology Research, NIST, Rockville, Maryland 20850 (United States); Chen, Lei, E-mail: lei.chen@nist.gov [NIST Center for Nanoscale Science and Technology, Gaithersburg, Maryland 20899-8313 (United States); Gawrisch, Klaus [Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892 (United States)

    2015-01-15

    Nanoporous platinum membranes can be straightforwardly fabricated by forming a Pt coating inside the nanopores of anodic alumina membranes (AAO) using atomic layer deposition (ALD). However, the high-aspect-ratio of AAO makes Pt ALD very challenging. By tuning the process deposition temperature and precursor exposure time, enhanced infiltration depth along with conformal coating was achieved for Pt ALD inside the AAO templates. Cross-sectional scanning electron microscopy/energy dispersive x-ray spectroscopy and small angle neutron scattering were employed to analyze the Pt coverage and thickness inside the AAO nanopores. Additionally, one application of platinum-coated membrane was demonstrated by creating a high-density protein-functionalized interface.

  18. ALD Functionalized Nanoporous Gold: Thermal Stability, Mechanical Properties, and Catalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Biener, M M; Biener, J; Wichmann, A; Wittstock, A; Baumann, T F; Baeumer, M; Hamza, A V

    2011-03-24

    Nanoporous metals have many technologically promising applications but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only one-nm-thick oxide films can stabilize the nanoscale morphology of np-Au up to 1000 C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO{sub 2} ALD coatings. Our results open the door to high temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications.

  19. Selectively Sized Graphene-Based Nanopores for in Situ Single Molecule Sensing.

    Science.gov (United States)

    Crick, Colin R; Sze, Jasmine Y Y; Rosillo-Lopez, Martin; Salzmann, Christoph G; Edel, Joshua B

    2015-08-19

    The use of nanopore biosensors is set to be extremely important in developing precise single molecule detectors and providing highly sensitive advanced analysis of biological molecules. The precise tailoring of nanopore size is a significant step toward achieving this, as it would allow for a nanopore to be tuned to a corresponding analyte. The work presented here details a methodology for selectively opening nanopores in real-time. The tunable nanopores on a quartz nanopipette platform are fabricated using the electroetching of a graphene-based membrane constructed from individual graphene nanoflakes (ø ∼30 nm). The device design allows for in situ opening of the graphene membrane, from fully closed to fully opened (ø ∼25 nm), a feature that has yet to be reported in the literature. The translocation of DNA is studied as the pore size is varied, allowing for subfeatures of DNA to be detected with slower DNA translocations at smaller pore sizes, and the ability to observe trends as the pore is opened. This approach opens the door to creating a device that can be target to detect specific analytes.

  20. Size effects of pore density and solute size on water osmosis through nanoporous membrane.

    Science.gov (United States)

    Zhao, Kuiwen; Wu, Huiying

    2012-11-15

    Understanding the behavior of osmotic transport across nanoporous membranes at molecular level is critical to their design and applications, and it is also beneficial to the comprehension of the mechanism of biological transmembrane transport processes. Pore density is an important parameter for nanoporous membranes. To better understand the influence of pore density on osmotic transport, we have performed systematic molecular dynamics simulations on water osmosis across nanoporous membranes with different pore densities (i.e., number of pores per unit area of membrane). The simulation results reveal that significant size effects occur when the pore density is so high that the center-to-center distance between neighboring nanopores is comparable to the solute size. The size effects are independent of the pore diameter and solute concentration. A simple quantitative correlation between pore density, solute size, and osmotic flux has been established. The results are excellently consistent with the theoretical predictions. It is also shown that solute hydration plays an important role in real osmotic processes. Solute hydration strengthens the size effects of pore density on osmotic processes due to the enlarged effective solute size induced by hydration. The influence of pore density, solute size, and solute hydration on water osmosis through nanoporous membranes can be introduced to eliminate the deviations of real osmotic processes from ideal behavior.

  1. Enhanced PEC performance of nanoporous Si photoelectrodes by covering HfO2 and TiO2 passivation layers.

    Science.gov (United States)

    Xing, Zhuo; Ren, Feng; Wu, Hengyi; Wu, Liang; Wang, Xuening; Wang, Jingli; Wan, Da; Zhang, Guozhen; Jiang, Changzhong

    2017-03-02

    Nanostructured Si as the high efficiency photoelectrode material is hard to keep stable in aqueous for water splitting. Capping a passivation layer on the surface of Si is an effective way of protecting from oxidation. However, it is still not clear in the different mechanisms and effects between insulating oxide materials and oxide semiconductor materials as passivation layers. Here, we compare the passivation effects, the photoelectrochemical (PEC) properties, and the corresponding mechanisms between the HfO2/nanoporous-Si and the TiO2/nanoporous-Si by I-V curves, Motte-schottky (MS) curves, and electrochemical impedance spectroscopy (EIS). Although the saturated photocurrent densities of the TiO2/nanoporous Si are lower than that of the HfO2/nanoporous Si, the former is more stable than the later.

  2. Electrochemistry at the edge of a single graphene layer in a nanopore

    DEFF Research Database (Denmark)

    Banerjee, Sutanuka; Shim, Jeong; Rivera, J.

    2013-01-01

    edge structure which, along with the atomically thin nature of the embedded graphene electrode, demonstrates electrochemical current densities as high as 1.2 × 10 A/cm. The graphene edge embedded structure offers a unique capability to study the electrochemical exchange at an individual graphene edge......, isolated from the basal plane electrochemical activity. We also report ionic current modulation in the nanopore by biasing the embedded graphene terminal with respect to the electrodes in the fluid. The high electrochemical specific current density for a graphene nanopore-based device can have many...

  3. High order ADER schemes for a unified first order hyperbolic formulation of Newtonian continuum mechanics coupled with electro-dynamics

    Science.gov (United States)

    Dumbser, Michael; Peshkov, Ilya; Romenski, Evgeniy; Zanotti, Olindo

    2017-11-01

    proposed model is that the propagation speeds of all physical processes, including dissipative processes, are finite. The model is discretized using high order accurate ADER discontinuous Galerkin (DG) finite element schemes with a posteriori subcell finite volume limiter and using high order ADER-WENO finite volume schemes. We show numerical test problems that explore a rather large parameter space of the model ranging from ideal MHD, viscous and resistive MHD over pure electro-dynamics to moving dielectric elastic solids in a magnetic field.

  4. Practical aspects of spherical near-field antenna measurements using a high-order probe

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Pivnenko, Sergey; Nielsen, Jeppe Majlund

    2006-01-01

    Two practical aspects related to accurate antenna pattern characterization by probe-corrected spherical near-field antenna measurements with a high-order probe are examined. First, the requirements set by an arbitrary high-order probe on the scanning technique are pointed out. Secondly, a channel...... balance calibration procedure for a high-order dual-port probe with non-identical ports is presented, and the requirements set by this procedure for the probe are discussed....

  5. High-order evolving surface finite element method for parabolic problems on evolving surfaces

    OpenAIRE

    Kovács, Balázs

    2016-01-01

    High-order spatial discretisations and full discretisations of parabolic partial differential equations on evolving surfaces are studied. We prove convergence of the high-order evolving surface finite element method, by showing high-order versions of geometric approximation errors and perturbation error estimates and by the careful error analysis of a modified Ritz map. Furthermore, convergence of full discretisations using backward difference formulae and implicit Runge-Kutta methods are als...

  6. A high order multi-resolution solver for the Poisson equation with application to vortex methods

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Spietz, Henrik Juul; Walther, Jens Honore

    A high order method is presented for solving the Poisson equation subject to mixed free-space and periodic boundary conditions by using fast Fourier transforms (FFT). The high order convergence is achieved by deriving mollified Green’s functions from a high order regularization function which...... provides a correspondingly smooth solution to the Poisson equation.The high order regularization function may be obtained analogous to the approximate deconvolution method used in turbulence models and strongly relates to deblurring algorithms used in image processing. At first we show that the regularized...

  7. SDS-assisted protein transport through solid-state nanopores

    NARCIS (Netherlands)

    Restrepo Perez, L.; John, Shalini; Aksimentiev, Aleksei; Joo, C.; Dekker, C.

    2017-01-01

    Using nanopores for single-molecule sequencing of proteins – similar to nanopore-based sequencing of DNA – faces multiple challenges, including unfolding of the complex tertiary structure of the proteins and enforcing their unidirectional translocation through nanopores. Here, we combine molecular

  8. Real-time single-molecule electronic DNA sequencing by synthesis using polymer-tagged nucleotides on a nanopore array.

    Science.gov (United States)

    Fuller, Carl W; Kumar, Shiv; Porel, Mintu; Chien, Minchen; Bibillo, Arek; Stranges, P Benjamin; Dorwart, Michael; Tao, Chuanjuan; Li, Zengmin; Guo, Wenjing; Shi, Shundi; Korenblum, Daniel; Trans, Andrew; Aguirre, Anne; Liu, Edward; Harada, Eric T; Pollard, James; Bhat, Ashwini; Cech, Cynthia; Yang, Alexander; Arnold, Cleoma; Palla, Mirkó; Hovis, Jennifer; Chen, Roger; Morozova, Irina; Kalachikov, Sergey; Russo, James J; Kasianowicz, John J; Davis, Randy; Roever, Stefan; Church, George M; Ju, Jingyue

    2016-05-10

    DNA sequencing by synthesis (SBS) offers a robust platform to decipher nucleic acid sequences. Recently, we reported a single-molecule nanopore-based SBS strategy that accurately distinguishes four bases by electronically detecting and differentiating four different polymer tags attached to the 5'-phosphate of the nucleotides during their incorporation into a growing DNA strand catalyzed by DNA polymerase. Further developing this approach, we report here the use of nucleotides tagged at the terminal phosphate with oligonucleotide-based polymers to perform nanopore SBS on an α-hemolysin nanopore array platform. We designed and synthesized several polymer-tagged nucleotides using tags that produce different electrical current blockade levels and verified they are active substrates for DNA polymerase. A highly processive DNA polymerase was conjugated to the nanopore, and the conjugates were complexed with primer/template DNA and inserted into lipid bilayers over individually addressable electrodes of the nanopore chip. When an incoming complementary-tagged nucleotide forms a tight ternary complex with the primer/template and polymerase, the tag enters the pore, and the current blockade level is measured. The levels displayed by the four nucleotides tagged with four different polymers captured in the nanopore in such ternary complexes were clearly distinguishable and sequence-specific, enabling continuous sequence determination during the polymerase reaction. Thus, real-time single-molecule electronic DNA sequencing data with single-base resolution were obtained. The use of these polymer-tagged nucleotides, combined with polymerase tethering to nanopores and multiplexed nanopore sensors, should lead to new high-throughput sequencing methods.

  9. Nanoporous Metals with Structural Hierarchy: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Juarez, Theresa [Department of Aerospace and Mechanical Engineering, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles CA 90089 USA; Biener, Juergen [Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, Livermore CA USA; Weissmüller, Jörg [Institute of Materials Physics and Technology, Hamburg University of Technology, Hamburg, Germany, and Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht Geesthacht Germany; Hodge, Andrea M. [Department of Aerospace and Mechanical Engineering, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles CA 90089 USA

    2017-08-09

    Nanoporous (np) metals have generated much interest since they combine several desirable material characteristics, such as high surface area, mechanical size effects, and high conductivity. Most of the research has been focused on np Au due to its relatively straightforward synthesis, chemical stability, and many promising applications in the fields of catalysis and actuation. Other materials, such as np-Cu, Ag, and Pd have also been studied. This review discusses recent advances in the field of np metals, focusing on new research areas that implement and leverage structural hierarchy while using np metals as their base structural constituents. First, we focus on single-element porous metals that are made of np metals at the fundamental level, but synthesized with additional levels of porosity. Second, we discuss the fabrication of composite structures, which use auxiliary materials to enhance the properties of np metals. Important applications of these hierarchical materials, especially in the fields of catalysis and electrochemistry, are also reviewed. Finally, we conclude with a discussion about future opportunities for the advancement and application of np metals.

  10. On site DNA barcoding by nanopore sequencing.

    Directory of Open Access Journals (Sweden)

    Michele Menegon

    Full Text Available Biodiversity research is becoming increasingly dependent on genomics, which allows the unprecedented digitization and understanding of the planet's biological heritage. The use of genetic markers i.e. DNA barcoding, has proved to be a powerful tool in species identification. However, full exploitation of this approach is hampered by the high sequencing costs and the absence of equipped facilities in biodiversity-rich countries. In the present work, we developed a portable sequencing laboratory based on the portable DNA sequencer from Oxford Nanopore Technologies, the MinION. Complementary laboratory equipment and reagents were selected to be used in remote and tough environmental conditions. The performance of the MinION sequencer and the portable laboratory was tested for DNA barcoding in a mimicking tropical environment, as well as in a remote rainforest of Tanzania lacking electricity. Despite the relatively high sequencing error-rate of the MinION, the development of a suitable pipeline for data analysis allowed the accurate identification of different species of vertebrates including amphibians, reptiles and mammals. In situ sequencing of a wild frog allowed us to rapidly identify the species captured, thus confirming that effective DNA barcoding in the field is possible. These results open new perspectives for real-time-on-site DNA sequencing thus potentially increasing opportunities for the understanding of biodiversity in areas lacking conventional laboratory facilities.

  11. Phonon bottleneck identification in disordered nanoporous materials

    Science.gov (United States)

    Romano, Giuseppe; Grossman, Jeffrey C.

    2017-09-01

    Nanoporous materials are a promising platform for thermoelectrics in that they offer high thermal conductivity tunability while preserving good electrical properties, a crucial requirement for high-efficiency thermal energy conversion. Understanding the impact of the pore arrangement on thermal transport is pivotal to engineering realistic materials, where pore disorder is unavoidable. Although there has been considerable progress in modeling thermal size effects in nanostructures, it has remained a challenge to screen such materials over a large phase space due to the slow simulation time required for accurate results. We use density functional theory in connection with the Boltzmann transport equation to perform calculations of thermal conductivity in disordered porous materials. By leveraging graph theory and regressive analysis, we identify the set of pores representing the phonon bottleneck and obtain a descriptor for thermal transport, based on the sum of the pore-pore distances between such pores. This approach provide a simple tool to estimate phonon suppression in realistic porous materials for thermoelectric applications and enhance our understanding of heat transport in disordered materials.

  12. Co-delivery of ibuprofen and gentamicin from nanoporous anodic titanium dioxide layers.

    Science.gov (United States)

    Pawlik, Anna; Jarosz, Magdalena; Syrek, Karolina; Sulka, Grzegorz D

    2017-04-01

    Although single-drug therapy may prove insufficient in treating bacterial infections or inflammation after orthopaedic surgeries, complex therapy (using both an antibiotic and an anti-inflammatory drug) is thought to address the problem. Among drug delivery systems (DDSs) with prolonged drug release profiles, nanoporous anodic titanium dioxide (ATO) layers on Ti foil are very promising. In the discussed research, ATO samples were synthesized via a three-step anodization process in an ethylene glycol-based electrolyte with fluoride ions. The third step lasted 2, 5 and 10min in order to obtain different thicknesses of nanoporous layers. Annealing the as-prepared amorphous layers at the temperature of 400°C led to obtaining the anatase phase. In this study, water-insoluble ibuprofen and water-soluble gentamicin were used as model drugs. Three different drug loading procedures were applied. The desorption-desorption-diffusion (DDD) model of the drug release was fitted to the experimental data. The effects of crystalline structure, depth of TiO2 nanopores and loading procedure on the drug release profiles were examined. The duration of the drug release process can be easily altered by changing the drug loading sequence. Water-soluble gentamicin is released for a long period of time if gentamicin is loaded in ATO as the first drug. Additionally, deeper nanopores and anatase phase suppress the initial burst release of drugs. These results confirm that factors such as morphological and crystalline structure of ATO layers, and the procedure of drug loading inside nanopores, allow to alter the drug release performance of nanoporous ATO layers. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Measurements of High Order Modes in High Phase Advance Damped Detuned Accelerating Structure for NLC

    CERN Document Server

    Khabiboulline, N; Carter, H

    2004-01-01

    The RF Technology Development group at Fermilab is working together with the NLC and JLC groups at SLAC and KEK on developing technology for room temperature X-band accelerating structures for a future linear collider. We have built several series of structures for high gradient tests. We have also built 150° phase advance per cell, 60 cm long, damped and detuned structures (HDDS or FXC series). Some of these structures will be used for the 8-pack test at SLAC by the end of 2004, as part of the JLC/NLC effort to demonstrate the readiness of room temperature RF technology for a linear collider. HDSS structures are very close to the final design for the linear collider, and it was very interesting to study the properties of high order modes in the structures produced by semi-industrial methods. In this study advanced RF technique and methods developed at Fermilab for structure low power testing and tuning have been used. The results of these measurements are presented in this paper.

  14. High-order ionospheric effects on electron density estimation from Fengyun-3C GPS radio occultation

    Science.gov (United States)

    Li, Junhai; Jin, Shuanggen

    2017-03-01

    GPS radio occultation can estimate ionospheric electron density and total electron content (TEC) with high spatial resolution, e.g., China's recent Fengyun-3C GPS radio occultation. However, high-order ionospheric delays are normally ignored. In this paper, the high-order ionospheric effects on electron density estimation from the Fengyun-3C GPS radio occultation data are estimated and investigated using the NeQuick2 ionosphere model and the IGRF12 (International Geomagnetic Reference Field, 12th generation) geomagnetic model. Results show that the high-order ionospheric delays have large effects on electron density estimation with up to 800 el cm-3, which should be corrected in high-precision ionospheric density estimation and applications. The second-order ionospheric effects are more significant, particularly at 250-300 km, while third-order ionospheric effects are much smaller. Furthermore, the high-order ionospheric effects are related to the location, the local time, the radio occultation azimuth and the solar activity. The large high-order ionospheric effects are found in the low-latitude area and in the daytime as well as during strong solar activities. The second-order ionospheric effects have a maximum positive value when the radio occultation azimuth is around 0-20°, and a maximum negative value when the radio occultation azimuth is around -180 to -160°. Moreover, the geomagnetic storm also affects the high-order ionospheric delay, which should be carefully corrected.

  15. One-step synthesis of zero-dimensional hollow nanoporous gold nanoparticles with enhanced methanol electrooxidation performance

    Science.gov (United States)

    Pedireddy, Srikanth; Lee, Hiang Kwee; Tjiu, Weng Weei; Phang, In Yee; Tan, Hui Ru; Chua, Shu Quan; Troadec, Cedric; Ling, Xing Yi

    2014-09-01

    Nanoporous gold with networks of interconnected ligaments and highly porous structure holds stimulating technological implications in fuel cell catalysis. Current syntheses of nanoporous gold mainly revolve around de-alloying approaches that are generally limited by stringent and harsh multistep protocols. Here we develop a one-step solution phase synthesis of zero-dimensional hollow nanoporous gold nanoparticles with tunable particle size (150-1,000 nm) and ligament thickness (21-54 nm). With faster mass diffusivity, excellent specific electroactive surface area and large density of highly active surface sites, our zero-dimensional nanoporous gold nanoparticles exhibit ~1.4 times enhanced catalytic activity and improved tolerance towards carbonaceous species, demonstrating their superiority over conventional nanoporous gold sheets. Detailed mechanistic study also reveals the crucial heteroepitaxial growth of gold on the surface of silver chloride templates, implying that our synthetic protocol is generic and may be extended to the synthesis of other nanoporous metals via different templates.

  16. Nanoporous characteristics of sol—gel-derived ZnO thin film

    Science.gov (United States)

    Ansari, Anees A.; Khan, M. A. M.; Alhoshan, M.; Alrokayan, S. A.; Alsalhi, M. S.

    2012-04-01

    Sol—gel-derived nanoporous ZnO film has been successfully deposited on glass substrate at 200 °C and subsequently annealed at different temperatures of 300, 400 and 600 °C. Atomic force micrographs demonstrated that the film was crack-free, and that granular nanoparticles were homogenously distributed on the film surface. The average grain size of the nanoparticles and RMS roughness of the scanned surface area was 10 nm and 13.6 nm, respectively, which is due to the high porosity of the film. Photoluminescence (PL) spectra of the nanoporous ZnO film at room temperature show a diffused band, which might be due to an increased amount of oxygen vacancies on the lattice surface. The observed results of the nanoporous ZnO film indicates a promising application in the development of electrochemical biosensors due to the porosity of film enhancing the higher loading of biomacromolecules (enzyme and proteins).

  17. Preparation of Fe3O4Spherical Nanoporous Particles Facilitated by Polyethylene Glycol 4000

    Directory of Open Access Journals (Sweden)

    Wang Li-Li

    2009-01-01

    Full Text Available Abstract Much interest has been attracted to the magnetic materials with porous structure because of their unique properties and potential applications. In this report, Fe3O4nanoporous particles assembled from small Fe3O4nanoparticles have been prepared by thermal decomposition of iron acetylacetonate in the presence of polyethylene glycol 4000. The size of the spherical nanoporous particles is 100–200 nm. Surface area measurement shows that these Fe3O4nanoporous particles have a high surface area of 87.5 m2/g. Magnetization measurement and Mössbauer spectrum indicate that these particles are nearly superparamagnetic at room temperature. It is found that the morphology of the products is greatly influenced by polyethylene glycol concentration and the polymerization degree of polyethylene glycol. Polyethylene glycol molecules are believed to facilitate the formation of the spherical assembly.

  18. Luminescence of Nanoporous Si and ALD-Deposited ZnO on Nanoporous Si Substrate

    Science.gov (United States)

    Pham, Vuong-Hung; Tam, Phuong Dinh; Dung, Nguyen Huu; Nguyen, Duy-Hung; Huy, Pham Thanh

    2017-08-01

    This paper reports the attempt at synthesizing nanoporous silicon (Si) with a dendritic-like structure and atomic layer deposition (ALD) of ZnO on nanoporous Si to control light emission intensity and emission center by applying an optimum voltage, etching time and thickness of ZnO layer. The dendritic-like structure of nanoporous Si was formed with low etching voltages of 5-10 V. Fourier transform infrared absorption spectra of the nanoporous Si reveals that the intensities of hydride stretching, SiH2 scissor mode and Si-O-Si vibration peak increase with the increasing of etching time. The formation of a thick dendritic-like structure with an increasing SiH2 bond resulted in significant enhancement of luminescence. In addition, the ALD-deposited ZnO layer on nanoporous Si resulted in light emission from both ZnO and nanoporous Si under a single excitation source. These results suggest the potential application of an ALD-deposited ZnO layer on nanoporous Si in designing materials for advanced optoelectronics.

  19. High-Order Calderón Preconditioned Time Domain Integral Equation Solvers

    KAUST Repository

    Valdes, Felipe

    2013-05-01

    Two high-order accurate Calderón preconditioned time domain electric field integral equation (TDEFIE) solvers are presented. In contrast to existing Calderón preconditioned time domain solvers, the proposed preconditioner allows for high-order surface representations and current expansions by using a novel set of fully-localized high-order div-and quasi curl-conforming (DQCC) basis functions. Numerical results demonstrate that the linear systems of equations obtained using the proposed basis functions converge rapidly, regardless of the mesh density and of the order of the current expansion. © 1963-2012 IEEE.

  20. High order SSB modulation and its application for advanced optical comb generation based on RFS

    Science.gov (United States)

    Sun, Lin; Du, Jiangbing; Li, Lu; He, Zuyuan

    2015-11-01

    In this work, a method for high-order single sideband (SSB) modulation is demonstrated. Extended frequency shifting can be obtained based on the high-order SSB modulator. The design of the 2nd and 3rd order SSB modulators are presented and investigated based on simulations. The demonstrated high-order SSB modulators can be used for advanced optical comb generation when they are configured in recirculating frequency shifter (RFS). Optical comb with significantly enlarged carrier-to-carrier spacing can be obtained and thus applications including wavelength division multiplexing (WDM) communication, optical frequency domain reflectometry (OFDR) and so on can be benefited.

  1. Electrically generated eddies at an eightfold stagnation point within a nanopore.

    Science.gov (United States)

    Sherwood, J D; Mao, M; Ghosal, S

    2014-11-01

    Electrically generated flows around a thin dielectric plate pierced by a cylindrical hole are computed numerically. The geometry represents that of a single nanopore in a membrane. When the membrane is uncharged, flow is due solely to induced charge electroosmosis, and eddies are generated by the high fields at the corners of the nanopore. These eddies meet at stagnation points. If the geometry is chosen correctly, the stagnation points merge to form a single stagnation point at which four streamlines cross at a point and eight eddies meet.

  2. Efficiency Benchmarking of an Energy Stable High-Order Finite Difference Discretization

    NARCIS (Netherlands)

    van der Weide, Edwin Theodorus Antonius; Giangaspero, G.; Svärd, M

    2015-01-01

    In this paper, results are presented for a number of benchmark cases, proposed at the 2nd International Workshop on High-Order CFD Methods in Cologne, Germany, in 2013. A robust high-order-accurate finite difference method was used that was developed during the last 10–15 years. The robustness stems

  3. Derivation and test of high order fluid model for streamer discharges

    NARCIS (Netherlands)

    A. Markosyan (Aram); S. Dujko (Sasa); U. Ebert (Ute); A. Blaszczyk; R. Hiptmair; P. Leuchtmann; J. Ostrowski

    2012-01-01

    textabstractA high order fluid model for streamer dynamics is developed by closing the system after the 4th moment of the Boltzmann equation in local mean energy approximation. This is done by approximating the high order pressure tensor in the heat flux equation through the previous moments.

  4. PREFACE New developments in nanopore research—from fundamentals to applications New developments in nanopore research—from fundamentals to applications

    Science.gov (United States)

    Albrecht, Tim; Edel, Joshua B.; Winterhalter, Mathias

    2010-11-01

    Biological and solid-state nanopores are an exciting field of research, which has seen a rapid development over the last 10 to 20 years. Activities in this area range from theoretical and experimental work on the underlying fundamental (bio)physics to applications in single-molecule biosensing. And while the prospect of DNA sequencing continues to be a major driving force, other applications with potentially similar impact begin to emerge, for example the detection of small molecules, proteins, protein/protein and protein/DNA complexes, and RNA to name just a few. It has also become apparent that both classes of nanopore devices have intrinsic advantages and disadvantages; hybrid structures combining the better of the two worlds would be a logical consequence and are beginning to appear in the literature. Many other highly innovative ideas and concepts continue to emerge and the number of nanopore-related publications has increased drastically over recent years. We found that more than 100 research groups worldwide are active in this area; several commercial settings are in the process of translating fundamental research into real-life applications. We therefore felt that now is the right time to showcase these new developments in a special issue: to inspire researchers active in the field, to liberate inherent synergies, and not least, to demonstrate to the outside world the current state-of-the-art and future opportunities. The title 'New developments in nanopore research—from fundamentals to applications' in some way reflects these ambitions and, even though not everyone invited was able to contribute, we were able to assemble 34 high-quality research papers from all over the world. We would like to acknowledge and thank all the contributors for their submissions, which made this special issue possible in the first place. Moreover, we would like to thank the staff at IOP Publishing for helping us with the administrative aspects and for coordinating the

  5. Multimetallic alloy nanotubes with nanoporous framework.

    Science.gov (United States)

    Choi, Bu-Seo; Lee, Young Wook; Kang, Shin Wook; Hong, Jong Wook; Kim, Jung; Park, Inkyu; Han, Sang Woo

    2012-06-26

    One-dimensional nanotubes (NTs) that consist of multiple metallic components are promising platforms for potential applications, whereas only a few synthetic methods of multimetallic NTs have been reported to date. In the present work, we developed a general synthesis route for the production of uniform multicomponent one-dimensional tubular nanostructures with various combinations of Pt, Pd, and Ag by using ZnO nanowires (NWs) as sacrificial templates. The ZnO NWs serve not only as physical templates but also as nucleation sites for the reduction of metal precursors, and thereby several metal precursors could be reduced simultaneously to produce multimetallic NTs. By using this approach, Pt-Pd, Pt-Ag, and Pd-Ag binary alloy NTs, and even Pt-Pd-Ag ternary alloy NTs could be successfully prepared. The prepared Pt-Pd binary alloy NTs exhibited improved electrocatalytic activity and stability toward ethanol oxidation due to their characteristic tubular morphology with well-interconnected nanoporous framework and synergism between two constituent metals. Furthermore, our approach can facilitate the fabrication of patterned multimetallic NT arrays on solid and flexible substrates with strong mechanical robustness. The present templating method does not require any extra steps to remove templates or additional surfactants which are often required to control the shape of nanostructures. This strategy offers a convenient, versatile, low-cost, and highly valuable approach to the fabrication of multimetallic nanostructures with various components and compositions.

  6. Nanoporous Au: an unsupported pure gold catalyst?

    Energy Technology Data Exchange (ETDEWEB)

    Wittstock, A; Neumann, B; Schaefer, A; Dumbuya, K; Kuebel, C; Biener, M; Zielasek, V; Steinrueck, H; Gottfried, M; Biener, J; Hamza, A; B?umer, M

    2008-09-04

    The unique properties of gold especially in low temperature CO oxidation have been ascribed to a combination of various effects. In particular, particle sizes below a few nm and specific particle-support interactions have been shown to play important roles. On the contrary, recent reports revealed that monolithic nanoporous gold (npAu) prepared by leaching a less noble metal, such as Ag, out of the corresponding alloy can also exhibit remarkably high catalytic activity for CO oxidation, even though no support is present. Therefore, it was claimed to be a pure and unsupported gold catalyst. We investigated npAu with respect to its morphology, surface composition and catalytic properties. In particular, we studied the reaction kinetics for low temperature CO oxidation in detail taking mass transport limitation due to the porous structure of the material into account. Our results reveal that Ag, even if removed almost completely from the bulk, segregates to the surface resulting in surface concentrations of up to 10 at%. Our data suggest that this Ag plays a significant role in activation of molecular oxygen. Therefore, npAu should be considered as a bimetallic catalyst rather than a pure Au catalyst.

  7. Spectroscopic study of partially-ordered semiconductor heterojunction under high pressure and high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yu, P.Y.; Martinez, G.; Zeman, J.; Uchida, K.

    2000-12-31

    Photoluminescence upconversion (PLU) is a phenomenon in which a sample emits photons with energy higher than that of the excitation photon. This effect has been observed in many materials including rare earth ions doped in insulating hosts and semiconductor heterostructures without using high power lasers as the excitation source. Recently, this effect has been observed also in partially CuPt-ordered GaInP{sub 2} epilayers grown on GaAs substrates. As a spectroscopic technique photoluminescence upconversion is particularly well suited for studying band alignment at heterojunction interface. The value of band-offset has been determined with meV precision using magneto-photoluminescence. Using the fact that the pressure coefficient of electrons in GaAs is higher than those in GaInP{sub 2} they have been able to manipulate the band-offset at the GaInP/GaAs interface. By converting the band-offset from Type I to Type II they were able to demonstrate that the efficiency of the upconversion process is greatly enhanced by a Type II band-offset.

  8. Rapid and Sensitive Detection of Lung Cancer Biomarker Using Nanoporous Biosensor Based on Localized Surface Plasmon Resonance Coupled with Interferometry

    Directory of Open Access Journals (Sweden)

    Jae-Sung Lee

    2015-01-01

    Full Text Available We propose a nanobiosensor to evaluate a lung cancer-specific biomarker. The nanobiosensor is based on an anodic aluminum oxide (AAO chip and functions on the principles of localized surface plasmon resonance (LSPR and interferometry. The pore-depth of the fabricated nanoporous AAO chip was 1 µm and was obtained using a two-step electrochemical anodization process. The sensor chip is sensitive to the refractive index (RI changes of the surrounding medium and also provides simple and label-free detection when specific antibodies are immobilized on the gold-deposited surface of the AAO chip. In order to confirm the effectiveness of the sensor, the antibodies were immobilized on the surface of the AAO chip, and the lung cancer-specific biomarker was applied atop of the immobilized-antibody layer using the self-assembled monolayer method. The nanoporous AAO chip was used as a sensor system to detect serum amyloid A1, which is a lung cancer-specific biomarker. The specific reaction of the antigen-antibody contributes to the change in the RI. This in turn causes a shift in the resonance spectrum in the refractive interference pattern. The limit of detection (LOD was found to be 100 ag/mL and the biosensor had high sensitivity over a wide concentration range.

  9. Functionalized nanoporous silicas for the immobilization of penicillin acylase

    Energy Technology Data Exchange (ETDEWEB)

    Maria Chong, A.S.; Zhao, X.S

    2004-10-15

    Nanoporous silica materials with uniform pore size and ordered structure have drawn growing interest of researchers since 1990s. A large-pore nanoporous material, SBA-15, was functionalized with organosilanes by co-condensation method in the presence of nonionic triblock copolymer P123 as a template under acidic conditions. The functionalization was demonstrated by using five organosilanes, namely 3-aminopropyltriethoxysilane (APTES), 3-mercaptopropyltrimethoxysilane (MPTMS), phenyltrimethoxysilane (PTMS), vinyltriethoxysilane (VTES), and 4-(triethoxysilyl)butyronitrile (TSBN), which modified the surface properties of the silica materials, enabling the materials to be a promising support for immobilization of biological molecules. The functionalized SBA-15 materials exhibited long-range ordering of two-dimensional hexagonal pore arrays of size ranging from 66 to 90 A as demonstrated by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and physical adsorption techniques. A variety of organosilane density in the range of 0.5-2.6 mmol/g was achieved as revealed by elemental analysis and solid-state nuclear magnetic resonance (NMR) techniques. The functionalized materials displayed improved properties for immobilization of penicillin acylase (PA) in comparison with pure-silica SBA-15. Such improvement is believed to be due to the enhanced surface hydrophobicity and electrostatic interactions of the functional groups with the enzyme.

  10. High-order fractional partial differential equation transform for molecular surface construction.

    Science.gov (United States)

    Hu, Langhua; Chen, Duan; Wei, Guo-Wei

    2013-01-01

    Fractional derivative or fractional calculus plays a significant role in theoretical modeling of scientific and engineering problems. However, only relatively low order fractional derivatives are used at present. In general, it is not obvious what role a high fractional derivative can play and how to make use of arbitrarily high-order fractional derivatives. This work introduces arbitrarily high-order fractional partial differential equations (PDEs) to describe fractional hyperdiffusions. The fractional PDEs are constructed via fractional variational principle. A fast fractional Fourier transform (FFFT) is proposed to numerically integrate the high-order fractional PDEs so as to avoid stringent stability constraints in solving high-order evolution PDEs. The proposed high-order fractional PDEs are applied to the surface generation of proteins. We first validate the proposed method with a variety of test examples in two and three-dimensional settings. The impact of high-order fractional derivatives to surface analysis is examined. We also construct fractional PDE transform based on arbitrarily high-order fractional PDEs. We demonstrate that the use of arbitrarily high-order derivatives gives rise to time-frequency localization, the control of the spectral distribution, and the regulation of the spatial resolution in the fractional PDE transform. Consequently, the fractional PDE transform enables the mode decomposition of images, signals, and surfaces. The effect of the propagation time on the quality of resulting molecular surfaces is also studied. Computational efficiency of the present surface generation method is compared with the MSMS approach in Cartesian representation. We further validate the present method by examining some benchmark indicators of macromolecular surfaces, i.e., surface area, surface enclosed volume, surface electrostatic potential and solvation free energy. Extensive numerical experiments and comparison with an established surface model

  11. High Order Thinking Skills: Analisis Soal dan Implementasinya dalam Pembelajaran Fisika di Sekolah Menengah Atas

    Directory of Open Access Journals (Sweden)

    Siswoyo Siswoyo

    2017-06-01

    Full Text Available Abstract This study investigated the implementation of High Order Thinking Skills in high school physics teaching focused on the analysis of the questions that were developed by teachers in Jakarta. Data obtained in training physics teachers in Jakarta. Teachers followed training on how to develop the learning of physics to develop higher order thinking skills. Then the teachers were asked to develop physics problems test as an instrument measuring tool of learning physics at school. Problems that have been made and then analyzed based on the general criteria and the criteria of making about a matter that meets the requirements of high-order thinking skills. Based on the analysis it can be concluded that to devise a matter of meeting the requirements of high order thinking skills required considerable time and good skills especially can apply Bloom's taxonomy in merumsukan indicators of competence to be measured. Keywords: High order thingking skills, physics, Bloom Taxonomy. Abstrak Penelitian ini mengkaji penerapan High Order Thinking Skills dalam pembelajaran fisika di SMA yang difokuskan pada analisis soal-soal yang dikembangkan oleh guru-guru DKI Jakarta. Data diperoleh dalam pelatihan guru fisika di DKI Jakarta. Sebelum membuat soal guru-guru mendapatkan pelatihan bagaimana mengembangkan pembelajaran fisika yang dapat mengembangkan keterampilan berpikir tingkat tinggi (high order thinking skills. Kemudian guru-guru diminta untuk mengembangkan soal-soal fisika sebagai instrumen alat ukur pembelajaran fisika di sekolahnya. Soal-soal yang telah dibuat kemudian dianalisis berdasarkan kriteria umum pembuatan soal dan kriteria soal yang memenuhi persyaratan high order thinking skills. Berdasarkan hasil analisis dapat disimpulkan bahwa untuk dapat menyusun soal yang memenuhi persyaratan high order thinking skills dibutuhkan waktu yang cukup lama dan keterampilan yang baik terutama dapat menerapkan taksonomi Bloom dalam merumsukan indikator

  12. Surfactant mobility in nanoporous glass films.

    Science.gov (United States)

    Kim, Taek-Soo; Mackie, Katherine; Zhong, Qiping; Peterson, Maria; Konno, Tomohisa; Dauskardt, Reinhold H

    2009-06-01

    Polymer molecules when physically confined at nanometer length scales diffuse nonclassically and very differently depending on their molecular weight and the nature of the confinement. Long polymers that exhibit "snakelike" reptation based mobility in melts may diffuse faster in confined nanometer sized cylinders with pore diameter d approximately 15 nm, and short polymers subject to Rouse dynamics have shown signatures of reptation and slower diffusion when confined in nanoporous glass with d approximately 4 nm. However, the mobility of short polymers with radii of gyration similar to a smaller pore diameter (d reptation based diffusion in the nanoscopic pore confinements. Such reptation mobility in agreement with theoretical predictions is not even observed in reptating polymer melts due to fluctuations of the entanglement pathway. The fixed pathways in the interconnected nanoporous films provide ideal nanoscale environments to explore mobility of confined molecules, and the results have implications for a number of technologies where nanoporous materials are in contact with surfactant molecules.

  13. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    applications as, e.g., membranes for separation and purification, templates for nanostructured materials, sensors, substrates for catalysis, low dielectric constant materials, photonic materials, and depots for controlled drug delivery. The development of nanoporous polymers with well controlled pore wall......Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential...... functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed...

  14. Ion transport through a graphene nanopore

    CERN Document Server

    Hu, Guohui; Ghosal, Sandip; 10.1088/0957-4484/23/39/395501

    2013-01-01

    Molecular dynamics simulation is utilized to investigate the ionic transport of NaCl in solution through a graphene nanopore under an applied electric field. Results show the formation of concentration polarization layers in the vicinity of the graphene sheet. The non-uniformity of the ion distribution gives rise to an electric pressure which drives vortical motions in the fluid if the electric field is sufficiently strong to overcome the influence of viscosity and thermal fluctuations. The relative importance of hydrodynamic transport and thermal fluctuations in determining the pore conductivity is investigated. A second important effect that is observed is the mass transport of water through the nanopore, with an average velocity proportional to the applied voltage and independent of the pore diameter. The flux arises as a consequence of the asymmetry in the ion distribution with respect to reflection about the plane of the graphene sheet. The accumulation of liquid molecules in the vicinity of the nanopore...

  15. ELECTROCHEMICAL PROPERTIES OF NANOPOROUS CARBON ELECTRODES

    Directory of Open Access Journals (Sweden)

    P.Nigu

    2002-01-01

    Full Text Available Electrical double layer and electrochemical characteristics at the nanoporous carbon | (C2H54NBF4 + acetonitrile interface have been studied by the cyclic voltammetry and impedance spectroscopy methods. The value of zero charge potential (0.23 V vs. SCE in H2O, the region of ideal polarizability and other characteristics have been established. Analysis of complex plane plots shows that the nanoporous carbon | x M (C2H54NBF4 + acetonitrile interface can be simulated by the equivalent circuit, in which the two parallel conduction parts in the solid and liquid phases are interconnected by the double layer capacitance in parallel with the complex admittance of hindered reaction of the charge transfer process. The values of the characteristic frequency depend on the electrolyte concentration and on the electrode potential, i.e. on the nature of ions adsorbed at the surface of nanoporous carbon electrode.

  16. A new design of a directional coupler for high order mode multiplexing in few mode fibers

    Science.gov (United States)

    Trichili, Abderrahmen; Ben Salem, Amine; Cherif, Rim; Zghal, Mourad; Forbes, Andrew

    2014-05-01

    We propose a new and versatile design of a directional coupler able to generate and multiplex high order modes in few mode fibers. The designed device can selectively generate five high order modes and multiplex them in a few mode fiber with an overall insertion loss not exceeding 3dB at the telecommunication wavelength λ = 1550 nm. The mode dependent loss is found to be weakly dependent to the wavelength. The proposed device is very promising for high order mode multiplexing and suitable for high bit-rate optical communication systems.

  17. SDS-assisted protein transport through solid-state nanopores.

    Science.gov (United States)

    Restrepo-Pérez, Laura; John, Shalini; Aksimentiev, Aleksei; Joo, Chirlmin; Dekker, Cees

    2017-08-17

    Using nanopores for single-molecule sequencing of proteins - similar to nanopore-based sequencing of DNA - faces multiple challenges, including unfolding of the complex tertiary structure of the proteins and enforcing their unidirectional translocation through nanopores. Here, we combine molecular dynamics (MD) simulations with single-molecule experiments to investigate the utility of SDS (Sodium Dodecyl Sulfate) to unfold proteins for solid-state nanopore translocation, while simultaneously endowing them with a stronger electrical charge. Our simulations and experiments prove that SDS-treated proteins show a considerable loss of the protein structure during the nanopore translocation. Moreover, SDS-treated proteins translocate through the nanopore in the direction prescribed by the electrophoretic force due to the negative charge impaired by SDS. In summary, our results suggest that SDS causes protein unfolding while facilitating protein translocation in the direction of the electrophoretic force; both characteristics being advantageous for future protein sequencing applications using solid-state nanopores.

  18. DNA Translocations through Solid-State Plasmonic Nanopores

    Science.gov (United States)

    2015-01-01

    Nanopores enable label-free detection and analysis of single biomolecules. Here, we investigate DNA translocations through a novel type of plasmonic nanopore based on a gold bowtie nanoantenna with a solid-state nanopore at the plasmonic hot spot. Plasmonic excitation of the nanopore is found to influence both the sensor signal (nanopore ionic conductance blockade during DNA translocation) and the process that captures DNA into the nanopore, without affecting the duration time of the translocations. Most striking is a strong plasmon-induced enhancement of the rate of DNA translocation events in lithium chloride (LiCl, already 10-fold enhancement at a few mW of laser power). This provides a means to utilize the excellent spatiotemporal resolution of DNA interrogations with nanopores in LiCl buffers, which is known to suffer from low event rates. We propose a mechanism based on plasmon-induced local heating and thermophoresis as explanation of our observations. PMID:25347403

  19. Antibacterial Activity of Zinc Oxide-Coated Nanoporous Alumina

    Science.gov (United States)

    2012-05-17

    Prior to deposition of the zinc oxide coating, the nanoporous alumina membranes were cleaned in situ using flowing ozone . Samples were exposed for 5 min...to an ozone partial pressure of ∼0.1 Torr; ozone was obtained from ultra high purity oxygen (flow rate = 400 sccm). Zinc oxide coatings were grown...H. Goudarzi, M. Navidinia, Gene Therapy and Molecular Biology 10B (2006) 263–267. [31] L.G. Miller, C. Quan, A. Shay, K. Mostafaie, K. Bharadwa, N

  20. Self-supporting nanoporous alumina membranes as substrates for hepatic cell cultures.

    Science.gov (United States)

    Hoess, Andreas; Thormann, Annika; Friedmann, Andrea; Heilmann, Andreas

    2012-09-01

    Membranes made from nanoporous alumina exhibit interesting properties for their use in biomedical research. They show high porosity and the pore diameters can be easily adjusted in a reproducible manner. Nanoporous alumina membranes are thus ideal substrates for the cultivation of polar cells (e.g., hepatocytes) or the establishment of indirect co-cultures. The porous nature of the material allows supply of nutrients to both sides of adherent cells and the exchange of molecules across the membrane. However, it is well-known that surface features in the nanometer range affect cellular behavior. In this study, the response of HepG2 cells to nanoporous alumina membranes with three different pore diameters, ranging from 50 to 250 nm, has been evaluated. The cellular interactions with the nanoporous materials were assessed by investigating cell adhesion, morphology, and proliferation. Cell functionality was measured by means of albumin production. The membranes supported good cell adhesion and spreading. Compared to tissue culture plastic, the cells on the porous substrates developed distinct focal adhesion sites and actin stress fibers. Additionally, electron microscopical investigations revealed the penetration of cellular extensions into pores with diameters bigger than 200 nm. Furthermore, cell proliferation significantly increased with an increase in pore diameter, whereas the albumin production followed a reverse trend. Thus, it seems to be possible to direct cellular behavior of HepG2 cells growing on nanoporous alumina by changing the pore diameter of the material. Hence, nanoporous alumina membranes can be useful culture substrates to develop new approaches in the field of liver tissue engineering. Copyright © 2012 Wiley Periodicals, Inc.

  1. Desalination of water by vapor-phase transport through hydrophobic nanopores

    Science.gov (United States)

    Lee, Jongho; Karnik, Rohit

    2010-08-01

    We propose a new approach to desalination of water whereby a pressure difference across a vapor-trapping nanopore induces selective transport of water by isothermal evaporation and condensation across the pore. Transport of water through a nanopore with saline water on one side and pure water on the other side under a pressure difference was theoretically analyzed under the rarefied gas assumption using a probabilistic framework that accounts for diffuse scattering from the pore walls as well as reflection from the menisci. The analysis revealed that in addition to salinity, temperature, and pressure difference, the nanopore aspect ratio and the probability of condensation of a water molecule incident on a meniscus from the vapor phase, known as the condensation coefficient, are key determinants of flux. The effect of condensation coefficient on mass flux becomes critical when the aspect ratio is small. However, the mass flux becomes independent of the condensation coefficient as the pore aspect ratio increases, converging to the Knudsen flux for long nanopores. For design of a nanopore membrane that can trap vapor, a minimum aspect ratio is derived for which coalescence of the two interfaces on either side of the nanopore remains energetically unfavorable. Based on this design criterion, the analysis suggests that mass flux in the range of 20-70 g/m2 s may be feasible if the system is operated at temperatures in the range of 30-50 °C. The proposed approach further decouples transport properties from material properties of the membrane, which opens the possibility of engineering membranes with appropriate materials that may lead to reverse osmosis membranes with improved flux, better selectivity, and high chlorine resistance.

  2. Technical Training on High-Order Spectral Analysis and Thermal Anemometry Applications

    Science.gov (United States)

    Maslov, A. A.; Shiplyuk, A. N.; Sidirenko, A. A.; Bountin, D. A.

    2003-01-01

    The topics of thermal anemometry and high-order spectral analyses were the subject of the technical training. Specifically, the objective of the technical training was to study: (i) the recently introduced constant voltage anemometer (CVA) for high-speed boundary layer; and (ii) newly developed high-order spectral analysis techniques (HOSA). Both CVA and HOSA are relevant tools for studies of boundary layer transition and stability.

  3. Time-Frequency Analysis Using Warped-Based High-Order Phase Modeling

    Directory of Open Access Journals (Sweden)

    Ioana Cornel

    2005-01-01

    Full Text Available The high-order ambiguity function (HAF was introduced for the estimation of polynomial-phase signals (PPS embedded in noise. Since the HAF is a nonlinear operator, it suffers from noise-masking effects and from the appearance of undesired cross-terms when multicomponents PPS are analyzed. In order to improve the performances of the HAF, the multi-lag HAF concept was proposed. Based on this approach, several advanced methods (e.g., product high-order ambiguity function (PHAF have been recently proposed. Nevertheless, performances of these new methods are affected by the error propagation effect which drastically limits the order of the polynomial approximation. This phenomenon acts especially when a high-order polynomial modeling is needed: representation of the digital modulation signals or the acoustic transient signals. This effect is caused by the technique used for polynomial order reduction, common for existing approaches: signal multiplication with the complex conjugated exponentials formed with the estimated coefficients. In this paper, we introduce an alternative method to reduce the polynomial order, based on the successive unitary signal transformation, according to each polynomial order. We will prove that this method reduces considerably the effect of error propagation. Namely, with this order reduction method, the estimation error at a given order will depend only on the performances of the estimation method.

  4. HiSeeker: Detecting High-Order SNP Interactions Based on Pairwise SNP Combinations

    Directory of Open Access Journals (Sweden)

    Jie Liu

    2017-05-01

    Full Text Available Detecting single nucleotide polymorphisms’ (SNPs interaction is one of the most popular approaches for explaining the missing heritability of common complex diseases in genome-wide association studies. Many methods have been proposed for SNP interaction detection, but most of them only focus on pairwise interactions and ignore high-order ones, which may also contribute to complex traits. Existing methods for high-order interaction detection can hardly handle genome-wide data and suffer from low detection power, due to the exponential growth of search space. In this paper, we proposed a flexible two-stage approach (called HiSeeker to detect high-order interactions. In the screening stage, HiSeeker employs the chi-squared test and logistic regression model to efficiently obtain candidate pairwise combinations, which have intermediate or significant associations with the phenotype for interaction detection. In the search stage, two different strategies (exhaustive search and ant colony optimization-based search are utilized to detect high-order interactions from candidate combinations. The experimental results on simulated datasets demonstrate that HiSeeker can more efficiently and effectively detect high-order interactions than related representative algorithms. On two real case-control datasets, HiSeeker also detects several significant high-order interactions, whose individual SNPs and pairwise interactions have no strong main effects or pairwise interaction effects, and these high-order interactions can hardly be identified by related algorithms.

  5. Detecting High-Order Epistasis in Nonlinear Genotype-Phenotype Maps.

    Science.gov (United States)

    Sailer, Zachary R; Harms, Michael J

    2017-03-01

    High-order epistasis has been observed in many genotype-phenotype maps. These multi-way interactions between mutations may be useful for dissecting complex traits and could have profound implications for evolution. Alternatively, they could be a statistical artifact. High-order epistasis models assume the effects of mutations should add, when they could in fact multiply or combine in some other nonlinear way. A mismatch in the "scale" of the epistasis model and the scale of the underlying map would lead to spurious epistasis. In this article, we develop an approach to estimate the nonlinear scales of arbitrary genotype-phenotype maps. We can then linearize these maps and extract high-order epistasis. We investigated seven experimental genotype-phenotype maps for which high-order epistasis had been reported previously. We find that five of the seven maps exhibited nonlinear scales. Interestingly, even after accounting for nonlinearity, we found statistically significant high-order epistasis in all seven maps. The contributions of high-order epistasis to the total variation ranged from 2.2 to 31.0%, with an average across maps of 12.7%. Our results provide strong evidence for extensive high-order epistasis, even after nonlinear scale is taken into account. Further, we describe a simple method to estimate and account for nonlinearity in genotype-phenotype maps. Copyright © 2017 Sailer and Harms.

  6. Dynamically Tunable Nanoporous Gold for Ionic and Molecular Separations

    Science.gov (United States)

    McCurry, Daniel Arthur

    The analysis of biomolecules, including proteins and DNA, is rapidly moving towards lab-on-a-chip devices in an effort to minimize sample volume and sample loss. Pores with diameters in the tens of nanometers range have gained significant attention recently through their use as single-molecule detectors and current rectifiers. Such devices must be designed for specific targets and the use of single pores limits high throughput applications. A membrane with adjustable properties in situ would provide a simple means of performing biomolecular separations and sample pre-concentration in microfluidic devices. The goal of this work is to fabricate a dynamic membrane that can be externally modulated and therefore tuned for specific analytes by uniting traditional separation methods based on size-exclusion principles with charge-based separations techniques. Gold serves as an attractive membrane material due to its high corrosion resistance, facile surface modification, and inherent conductivity. In our approach, a simple 2-day free-corrosion de-alloying procedure in concentrated nitric acid removes less noble metals (e.g. Cu, Ni, Zn, Ag) from Au-containing alloys to form a three-dimensional nanoporous network with a very large (4.2 +/- 0.8 m2 g-1 ) surface area density. The random orientation and small channel size of the network nearly guarantees analyte interaction with the walls. Pore sizes of 50 +/- 20 nm, as measured by scanning electron microscopy, have been attained, but adjusting de-alloying time, temperature, and pH are shown to extend this range. As a model system of dynamic control, UV-visible detection of anionic and cationic tracers transport across the nanoporous gold membrane has been monitored as a function of applied potential. Herein, surface area characterization of the bicontinuous porous structure with feature sizes on the nanometer scale was performed using the well-known Brunauer-Emmett-Teller gas adsorption isotherm, Pb underpotential deposition

  7. Fabrication and Optimization of a Nanoporous Platinum Electrode and a Non-enzymatic Glucose Micro-sensor on Silicon

    Directory of Open Access Journals (Sweden)

    Younghun Kim

    2008-10-01

    Full Text Available In this paper, optimal conditions for fabrication of nanoporous platinum (Pt were investigated in order to use it as a sensitive sensing electrode for silicon CMOS integrable non-enzymatic glucose micro-sensor applications. Applied charges, voltages, and temperatures were varied during the electroplating of Pt into the formed nonionic surfactant C16EO8 nano-scaled molds in order to fabricate nanoporous Pt electrodes with large surface roughness factor (RF, uniformity, and reproducibility. The fabricated nanoporous Pt electrodes were characterized using atomic force microscopy (AFM and electrochemical cyclic voltammograms. Optimal electroplating conditions were determined to be an applied charge of 35 mC/mm2, a voltage of -0.12 V, and a temperature of 25 °C, respectively. The optimized nanoporous Pt electrode had an electrochemical RF of 375 and excellent reproducibility. The optimized nanoporous Pt electrode was applied to fabricate non-enzymatic glucose micro-sensor with three electrode systems. The fabricated sensor had a size of 3 mm x 3 mm, air gap of 10 µm, working electrode (WE area of 4.4 mm2, and sensitivity of 37.5 µA•L/mmol•cm2. In addition, it showed large detection range from 0.05 to 30 mmolL-1 and stable recovery responsive to the step changes in glucose concentration.

  8. Nanoporous magnesium aluminometasilicate tablets for precise, controlled, and continuous dosing of chemical reagents and catalysts

    DEFF Research Database (Denmark)

    Ruhland, T.; Nielsen, S.D.; Holm, P.

    2007-01-01

    Mechanically robust tablets of nanoporous magnesium aluminometasilicate with high surface area and porosity can be loaded with a variety of organic and inorganic reagents and catalysts. The scope of this novel dosing methodology is demonstrated through the evaluation of 14 diverse organic reactions...

  9. High-Order Ghost-Fluid Method for Compressible Flow in Complex Geometry

    Science.gov (United States)

    Al Marouf, Mohamad; Samtaney, Ravi

    2014-11-01

    We present a high-order embedded boundary method for numerical solutions of the Compressible Navier Stokes (CNS) equations in arbitrary domains. A high-order ghost fluid method based on the PDEs multidimensional extrapolation approach of Aslam (J. Comput. Phys. 2003) is utilized to extrapolate the solution across the fluid-solid interface to impose boundary conditions. A fourth order accurate numerical time integration for the CNS is achieved by fourth order Runge-Kutta scheme, and a fourth order conservative finite volume scheme by McCorquodale & Colella (Comm. in App. Math. & Comput. Sci. 2011) is used to evaluate the fluxes. Resolution at the embedded boundary and high gradient regions is accomplished by applying block-structured adaptive mesh refinement. A number of numerical examples with different Reynolds number for a low Mach number flow over an airfoil and circular cylinder will be presented. Supported by OCRF-CRG grant at KAUST.

  10. Planck 2015 results: VII. High Frequency Instrument data processing: Time-ordered information and beams

    DEFF Research Database (Denmark)

    Adam, R.; Ade, P. A R; Aghanim, N.

    2016-01-01

    The Planck High Frequency Instrument (HFI) has observed the full sky at six frequencies (100, 143, 217, 353, 545, and 857 GHz) in intensity and at four frequencies in linear polarization (100, 143, 217, and 353 GHz). In order to obtain sky maps, the time-ordered information (TOI) containing the d...

  11. 78 FR 65744 - High End Ventures, Inc., Order of Suspension of Trading

    Science.gov (United States)

    2013-11-01

    ... COMMISSION High End Ventures, Inc., Order of Suspension of Trading October 21, 2013. It appears to the... investors require a suspension of trading in the securities of the above-listed company. Therefore, it is ordered, pursuant to Section 12(k) of the Securities Exchange Act of 1934, that trading in the securities...

  12. Laser-induced bound-state phases in high-order harmonic generation

    DEFF Research Database (Denmark)

    Etches, Adam; B. Gaarde, Mette; Bojer Madsen, Lars

    2012-01-01

    We present single-molecule and macroscopic calculations showing that laser-induced Stark shifts contribute significantly to the phase of high-order harmonics from polar molecules. This is important for orbital tomography, where phases of field-free dipole matrix elements are needed in order...

  13. High-order equations of motion in quantum mechanics and Galilean relativity

    Energy Technology Data Exchange (ETDEWEB)

    Fushchych, W.I. [Department of Mathematics, UMIST, Manchester (United Kingdom); Symenoh, Z.I. [Institute of Mathematics of the National Academy of Sciences of Ukraina, Kyiv (Ukraine)

    1997-03-21

    Linear partial differential equations of arbitrary order invariant under the Galilei transformations are described. Symmetry classification of potentials for these equations in two-dimensional space is carried out. High-order nonlinear partial differential equations invariant under the Galilei, extended Galilei and full Galilei algebras are studied. (author). Letter-to-the-editor.

  14. The Development of High-Order Methods for Real World Applications

    Science.gov (United States)

    2015-12-03

    three-stage 3rd order Runge-Kutta scheme Gottlieb and Shu [43] is used as the temporal discretization. Here we give a brief description. Rewrite the...Science and Engineering. Springer Berlin Heidelberg, pp. 47–95. [43] Gottlieb , S., Shu, C.-W., 2011. Strong stability-preserving high-order time dis

  15. Characterization of nanoporous gold electrodes for bioelectrochemical applications.

    Science.gov (United States)

    Scanlon, Micheál D; Salaj-Kosla, Urszula; Belochapkine, Serguei; MacAodha, Domhnall; Leech, Dónal; Ding, Yi; Magner, Edmond

    2012-01-31

    The high surface areas of nanostructured electrodes can provide for significantly enhanced surface loadings of electroactive materials. The fabrication and characterization of nanoporous gold (np-Au) substrates as electrodes for bioelectrochemical applications is described. Robust np-Au electrodes were prepared by sputtering a gold-silver alloy onto a glass support and subsequent dealloying of the silver component. Alloy layers were prepared with either a uniform or nonuniform distribution of silver and, post dealloying, showed clear differences in morphology on characterization with scanning electron microscopy. Redox reactions under kinetic control, in particular measurement of the charge required to strip a gold oxide layer, provided the most accurate measurements of the total electrochemically addressable electrode surface area, A(real). Values of A(real) up to 28 times that of the geometric electrode surface area, A(geo), were obtained. For diffusion-controlled reactions, overlapping diffusion zones between adjacent nanopores established limiting semi-infinite linear diffusion fields where the maximum current density was dependent on A(geo). The importance of measuring the surface area available for the immobilization was determined using the redox protein, cyt c. The area accessible to modification by a biological macromolecule, A(macro), such as cyt c was reduced by up to 40% compared to A(real), demonstrating that the confines of some nanopores were inaccessible to large macromolecules due to steric hindrances. Preliminary studies on the preparation of np-Au electrodes modified with osmium redox polymer hydrogels and Myrothecium verrucaria bilirubin oxidase (MvBOD) as a biocathode were performed; current densities of 500 μA cm(-2) were obtained in unstirred solutions. © 2011 American Chemical Society

  16. Nanocall: an open source basecaller for Oxford Nanopore sequencing data.

    Science.gov (United States)

    David, Matei; Dursi, L J; Yao, Delia; Boutros, Paul C; Simpson, Jared T

    2017-01-01

    The highly portable Oxford Nanopore MinION sequencer has enabled new applications of genome sequencing directly in the field. However, the MinION currently relies on a cloud computing platform, Metrichor (metrichor.com), for translating locally generated sequencing data into basecalls. To allow offline and private analysis of MinION data, we created Nanocall. Nanocall is the first freely available, open-source basecaller for Oxford Nanopore sequencing data and does not require an internet connection. Using R7.3 chemistry, on two E.coli and two human samples, with natural as well as PCR-amplified DNA, Nanocall reads have ∼68% identity, directly comparable to Metrichor '1D' data. Further, Nanocall is efficient, processing ∼2500 Kbp of sequence per core hour using the fastest settings, and fully parallelized. Using a 4 core desktop computer, Nanocall could basecall a MinION sequencing run in real time. Metrichor provides the ability to integrate the '1D' sequencing of template and complement strands of a single DNA molecule, and create a '2D' read. Nanocall does not currently integrate this technology, and addition of this capability will be an important future development. In summary, Nanocall is the first open-source, freely available, off-line basecaller for Oxford Nanopore sequencing data. Nanocall is available at github.com/mateidavid/nanocall, released under the MIT license. matei.david@oicr.on.caSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

  17. High Order Wavelet-Based Multiresolution Technology for Airframe Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An integrated framework is proposed for efficient prediction of rotorcraft and airframe noise. A novel wavelet-based multiresolution technique and high-order...

  18. ASYMPTOTICALLY OPTIMAL HIGH-ORDER ACCURATE ALGORITHMS FOR THE SOLUTION OF CERTAIN ELLIPTIC PDEs

    Energy Technology Data Exchange (ETDEWEB)

    Leonid Kunyansky, PhD

    2008-11-26

    The main goal of the project, "Asymptotically Optimal, High-Order Accurate Algorithms for the Solution of Certain Elliptic PDE's" (DE-FG02-03ER25577) was to develop fast, high-order algorithms for the solution of scattering problems and spectral problems of photonic crystals theory. The results we obtained lie in three areas: (1) asymptotically fast, high-order algorithms for the solution of eigenvalue problems of photonics, (2) fast, high-order algorithms for the solution of acoustic and electromagnetic scattering problems in the inhomogeneous media, and (3) inversion formulas and fast algorithms for the inverse source problem for the acoustic wave equation, with applications to thermo- and opto- acoustic tomography.

  19. Finite-Bandwidth Resonances of High-Order Axial Modes (HOAM) in a Gyrotron Cavity

    OpenAIRE

    Sabchevski, Svilen; IDEHARA, Toshitaka

    2014-01-01

    Finite-bandwidth resonances of high-order axial modes (HOAM) in an open gyrotron cavity are studied numerically using the GYROSIM problem-oriented software package for modelling, simulation and computer-aided design (CAD) of gyrotron tubes.

  20. Decay of high order optical vortices in anisotropic nonlinear optical media

    DEFF Research Database (Denmark)

    Mamaev, A.V.; Saffman, M.; Zozulya, A.A.

    1997-01-01

    We present an experimental and theoretical study of the decay of high order optical vortices in media with an anisotropic nonlocal nonlinearity. Vortices with charge n decay into an aligned array of n vortices of unit charge.......We present an experimental and theoretical study of the decay of high order optical vortices in media with an anisotropic nonlocal nonlinearity. Vortices with charge n decay into an aligned array of n vortices of unit charge....

  1. Single-order laser high harmonics in XUV for ultrafast photoelectron spectroscopy of molecular wavepacket dynamics

    Directory of Open Access Journals (Sweden)

    Mizuho Fushitani

    2016-11-01

    Full Text Available We present applications of extreme ultraviolet (XUV single-order laser harmonics to gas-phase ultrafast photoelectron spectroscopy. Ultrashort XUV pulses at 80 nm are obtained as the 5th order harmonics of the fundamental laser at 400 nm by using Xe or Kr as the nonlinear medium and separated from other harmonic orders by using an indium foil. The single-order laser harmonics is applied for real-time probing of vibrational wavepacket dynamics of I2 molecules in the bound and dissociating low-lying electronic states and electronic-vibrational wavepacket dynamics of highly excited Rydberg N2 molecules.

  2. Nanopores Created using an Internal Shadowmask Process

    NARCIS (Netherlands)

    de Vreede, Lennart; Berenschot, Johan W.; Tas, Niels Roelof; van den Beld, Wesley Theodorus Eduardus; Loessberg-Zahl, Joshua Taylor; van den Berg, Albert; Eijkel, Jan C.T.

    2016-01-01

    AbstractWe report on the manufacturing of nanopore through-holes by heating gold nanoparticles on a silicon oxide (SiO2) sheet, suspended in a silicon-rich nitride membrane (SiRN).Membrane patterning is performed using self-alignment by an internal shadow mask based process. A benefit of this

  3. Rapid resistome mapping using nanopore sequencing

    DEFF Research Database (Denmark)

    van der Helm, Eric; Imamovic, Lejla; Ellabaan, Mostafa M Hashim

    2017-01-01

    of bacterial infections. Yet, rapid workflows for resistome characterization are lacking. To address this challenge we developed the poreFUME workflow that deploys functional metagenomic selections and nanopore sequencing to resistome mapping. We demonstrate the approach by functionally characterizing the gut...

  4. Ion transport through a graphene nanopore.

    Science.gov (United States)

    Hu, Guohui; Mao, Mao; Ghosal, Sandip

    2012-10-05

    Molecular dynamics simulation is utilized to investigate the ionic transport of NaCl in solution through a graphene nanopore under an applied electric field. Results show the formation of concentration polarization layers in the vicinity of the graphene sheet. The nonuniformity of the ion distribution gives rise to an electric pressure which drives vortical motions in the fluid if the electric field is sufficiently strong to overcome the influence of viscosity and thermal fluctuations. The relative importance of hydrodynamic transport and thermal fluctuations in determining the pore conductivity is investigated. A second important effect that is observed is the mass transport of water through the nanopore, with an average velocity proportional to the applied voltage and independent of the pore diameter. The flux arises as a consequence of the asymmetry in the ion distribution which can be attributed to differing mobilities of the sodium and chlorine ions and to the polarity of water molecules. The accumulation of liquid molecules in the vicinity of the nanopore due to re-orientation of the water dipoles by the local electric field is seen to result in a local increase in the liquid density. Results confirm that the electric conductance is proportional to the nanopore diameter for the parameter regimes that we simulated. The occurrence of fluid vortices is found to result in an increase in the effective electrical conductance.

  5. Ultrafiltration by gyroid nanoporous polymer membranes

    DEFF Research Database (Denmark)

    Li, Li; Szewczykowski, Piotr Przemyslaw; Clausen, Lydia D.

    2011-01-01

    Gyroid nanoporous cross-linked 1,2-polybutadiene membranes with uniform pores were developed for ultrafiltration applications. The gyroid porosity has the advantage of isotropic percolation with no need for structure pre-alignment. The effects of solvent and surface photo-hydrophilization on perm...

  6. Analysis of electrolyte transport through charged nanopores

    NARCIS (Netherlands)

    Peters, P.B.; Roij, van R.; Bazant, M.Z.; Biesheuvel, P.M.

    2016-01-01

    We revisit the classical problem of flow of electrolyte solutions through charged capillary nanopores or nanotubes as described by the capillary pore model (also called "space charge" theory). This theory assumes very long and thin pores and uses a one-dimensional flux-force formalism which

  7. Analysis of electrolyte transport through charged nanopores

    NARCIS (Netherlands)

    Peters, P. B.; Roij, R. van; Bazant, M. Z.; Biesheuvel, P. M.

    2016-01-01

    We revisit the classical problem of the flow of an electrolyte solution through charged capillaries (nanopores). In the limit where the length of the capillary is much larger than its radius, the problem can be simplified to a one-dimensional averaged flux-force formalism that relates the relevant

  8. Propagation and power flow of high-order three-Airy beams

    Science.gov (United States)

    Liang, Yi; Chen, Yingkang; Wan, Lingyu

    2017-12-01

    We demonstrate experimentally propagation and evolution of high-order three-Airy beams in this letter. Our results show clearly that, a high-order three-Airy beam tends to evolve into a Laguerre-Gaussian-like beam, in consistence with previous prediction. Moreover, by analyzing the internal transverse power flow of three-Airy beams during propagation, we found that, as the order of three-Airy beams goes higher, the initial beam intensity distributes more in the "side lobes", and it takes longer propagation for the beams to reach a maximum peak intensity and then transform into patterns of corresponding Laguerre-Gaussian-like modes.

  9. Convergence of high order perturbative expansions in open system quantum dynamics.

    Science.gov (United States)

    Xu, Meng; Song, Linze; Song, Kai; Shi, Qiang

    2017-02-14

    We propose a new method to directly calculate high order perturbative expansion terms in open system quantum dynamics. They are first written explicitly in path integral expressions. A set of differential equations are then derived by extending the hierarchical equation of motion (HEOM) approach. As two typical examples for the bosonic and fermionic baths, specific forms of the extended HEOM are obtained for the spin-boson model and the Anderson impurity model. Numerical results are then presented for these two models. General trends of the high order perturbation terms as well as the necessary orders for the perturbative expansions to converge are analyzed.

  10. High Order Sliding Mode Control of Doubly-fed Induction Generator under Unbalanced Grid Faults

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

    2013-01-01

    This paper deals with a doubly-fed induction generator-based (DFIG) wind turbine system under grid fault conditions such as: unbalanced grid voltage, three-phase grid fault, using a high order sliding mode control (SMC). A second order sliding mode controller, which is robust with respect...... to matched internal or external disturbances, fast transient response and finite reaching time, is employed to reduce chattering phenomenon caused by high frequency switching of SMC, which serious exists in lower order SMC, and to overcome parameter dependence of traditional proportional integral (PI...

  11. Decomposition of conditional probability for high-order symbolic Markov chains

    Science.gov (United States)

    Melnik, S. S.; Usatenko, O. V.

    2017-07-01

    The main goal of this paper is to develop an estimate for the conditional probability function of random stationary ergodic symbolic sequences with elements belonging to a finite alphabet. We elaborate on a decomposition procedure for the conditional probability function of sequences considered to be high-order Markov chains. We represent the conditional probability function as the sum of multilinear memory function monomials of different orders (from zero up to the chain order). This allows us to introduce a family of Markov chain models and to construct artificial sequences via a method of successive iterations, taking into account at each step increasingly high correlations among random elements. At weak correlations, the memory functions are uniquely expressed in terms of the high-order symbolic correlation functions. The proposed method fills the gap between two approaches, namely the likelihood estimation and the additive Markov chains. The obtained results may have applications for sequential approximation of artificial neural network training.

  12. Electrophoretic Concentration and Electrical Lysis of Bacteria in a Microfluidic Device Using a Nanoporous Membrane

    Directory of Open Access Journals (Sweden)

    Md. Shehadul Islam

    2017-02-01

    Full Text Available Pathogenic bacteria such as Escherichia coli O157, Salmonella and Campylobacter are the main causes for food and waterborne illnesses. Lysis of these bacteria is an important component of the sample preparation for molecular identification of these pathogens. The pathogenicity of these bacteria is so high that they cause illness at very low concentrations (1–10 CFU/100 mL. Hence, there is a need to develop methods to collect a small number of such bacterial cells from a large sample volume and process them in an automated reagent-free manner. An electrical method to concentrate the bacteria and lyse them has been chosen here as it is reagent free and hence more conducive for online and automated sample preparation. We use commercially available nanoporous membranes sandwiched between two microfluidic channels to create thousands of parallel nanopore traps for bacteria, electrophoretically accumulate and then lyse them. The nanopores produce a high local electric field for lysis at moderate applied voltages, which could simplify instrumentation and enables lysis of the bacteria as it approaches them under an appropriate range of electric field (>1000 V/cm. Accumulation and lysis of bacteria on the nanoporous membrane is demonstrated by using the LIVE/DEAD BacLight Bacterial Viability Kit and quantified by fluorescence intensity measurements. The efficiency of the device was determined through bacterial culture of the lysate and was found to be 90% when a potential of 300 V was applied for 3 min.

  13. Hierarchical High-Order Functional Connectivity Networks and Selective Feature Fusion for MCI Classification.

    Science.gov (United States)

    Chen, Xiaobo; Zhang, Han; Lee, Seong-Whan; Shen, Dinggang

    2017-07-01

    Conventional Functional connectivity (FC) analysis focuses on characterizing the correlation between two brain regions, whereas the high-order FC can model the correlation between two brain region pairs. To reduce the number of brain region pairs, clustering is applied to group all the brain region pairs into a small number of clusters. Then, a high-order FC network can be constructed based on the clustering result. By varying the number of clusters, multiple high-order FC networks can be generated and the one with the best overall performance can be finally selected. However, the important information contained in other networks may be simply discarded. To address this issue, in this paper, we propose to make full use of the information contained in all high-order FC networks. First, an agglomerative hierarchical clustering technique is applied such that the clustering result in one layer always depends on the previous layer, thus making the high-order FC networks in the two consecutive layers highly correlated. As a result, the features extracted from high-order FC network in each layer can be decomposed into two parts (blocks), i.e., one is redundant while the other might be informative or complementary, with respect to its previous layer. Then, a selective feature fusion method, which combines sequential forward selection and sparse regression, is developed to select a feature set from those informative feature blocks for classification. Experimental results confirm that our novel method outperforms the best single high-order FC network in diagnosis of mild cognitive impairment (MCI) subjects.

  14. New Graphene Form of Nanoporous Monolith for Excellent Energy Storage.

    Science.gov (United States)

    Bi, Hui; Lin, Tianquan; Xu, Feng; Tang, Yufeng; Liu, Zhanqiang; Huang, Fuqiang

    2016-01-13

    Extraordinary tubular graphene cellular material of a tetrahedrally connected covalent structure was very recently discovered as a new supermaterial with ultralight, ultrastiff, superelastic, and excellent conductive characteristics, but no high specific surface area will keep it from any next-generation energy storage applications. Herein, we prepare another new graphene monolith of mesoporous graphene-filled tubes instead of hollow tubes in the reported cellular structure. This graphene nanoporous monolith is also composed of covalently bonded carbon network possessing high specific surface area of ∼1590 m(2) g(-1) and electrical conductivity of ∼32 S cm(-1), superior to graphene aerogels and porous graphene forms self-assembled by graphene oxide. This 3D graphene monolith can support over 10 000 times its own weight, significantly superior to CNT and graphene cellular materials with a similar density. Furthermore, pseudocapacitance-active functional groups are introduced into the new nanoporous graphene monolith as an electrode material in electrochemical capacitors. Surprisingly, the electrode of 3D mesoporous graphene has a specific capacitance of 303 F g(-1) and maintains over 98% retention after 10 000 cycles, belonging to the list for the best carbon-based active materials. The macroscopic mesoporous graphene monolith suggests the great potential as an electrode for supercapacitors in energy storage areas.

  15. Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics

    Science.gov (United States)

    Munje, Rujuta D.; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

    2015-09-01

    An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

  16. Multiscale Morphology of Nanoporous Copper Made from Intermetallic Phases.

    Science.gov (United States)

    Egle, Tobias; Barroo, Cédric; Janvelyan, Nare; Baumgaertel, Andreas C; Akey, Austin J; Biener, Monika M; Friend, Cynthia M; Bell, David C; Biener, Juergen

    2017-08-02

    Many application-relevant properties of nanoporous metals critically depend on their multiscale architecture. For example, the intrinsically high step-edge density of curved surfaces at the nanoscale provides highly reactive sites for catalysis, whereas the macroscale pore and grain morphology determines the macroscopic properties, such as mass transport, electrical conductivity, or mechanical properties. In this work, we systematically study the effects of alloy composition and dealloying conditions on the multiscale morphology of nanoporous copper (np-Cu) made from various commercial Zn-Cu precursor alloys. Using a combination of X-ray diffraction, electron backscatter diffraction, and focused ion beam cross-sectional analysis, our results reveal that the macroscopic grain structure of the starting alloy surprisingly survives the dealloying process, despite a change in crystal structure from body-centered cubic (Zn-Cu starting alloy) to face-centered cubic (Cu). The nanoscale structure can be controlled by the acid used for dealloying with HCl leading to a larger and more faceted ligament morphology compared to that of H3PO4. Anhydrous ethanol dehydrogenation was used as a probe reaction to test the effect of the nanoscale ligament morphology on the apparent activation energy of the reaction.

  17. Dispersion and optical gradient force from high-order mode coupling between two hyperbolic metamaterial waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanghui, E-mail: gsnuwgh@163.com; Zhang, Weifeng; Lu, Jiahui; Zhao, Huijun

    2016-08-12

    We analytically study dispersion properties and optical gradient forces of different-order transverse magnetic (TM) modes in two coupled hyperbolic metamaterial waveguides (HMMWs). According to Maxwell's equations, we obtain the dispersion relation of symmetric and antisymmetric modes, and calculate optical gradient forces of different-order modes by using Maxwell stress tensor. Numerical results show that the dispersion properties are dependent on the filling ratio, and the optical gradient forces of high-order TM modes are larger than the fundamental mode when the gap between two HMMWs is very narrow, but they weaken much faster than the case of low-order TM modes with the gap width increasing. In addition, the effects of the dielectric surrounding of waveguides on the coupling effect and optical gradient force are clarified. These properties offer an avenue for various optomechanical applications in optical sensors and actuators. - Highlights: • The dependence of dispersion properties in hyperbolic metamaterials on the filling ratio is analyzed. • It is possible that the optical gradient forces of high-order modes are larger than the fundamental mode. • Optical gradient forces of high-order modes weaken much faster than the case of low-order modes. • The influence of the dielectric surrounding on the coupling effect and optical gradient force are clarified.

  18. A Novel High Order Time Domain Vector Finite Element Method for the Simulation of Electromagnetic Devices

    Energy Technology Data Exchange (ETDEWEB)

    Rieben, Robert N. [Univ. of California, Davis, CA (United States)

    2004-01-01

    The goal of this dissertation is two-fold. The first part concerns the development of a numerical method for solving Maxwell's equations on unstructured hexahedral grids that employs both high order spatial and high order temporal discretizations. The second part involves the use of this method as a computational tool to perform high fidelity simulations of various electromagnetic devices such as optical transmission lines and photonic crystal structures to yield a level of accuracy that has previously been computationally cost prohibitive. This work is based on the initial research of Daniel White who developed a provably stable, charge and energy conserving method for solving Maxwell's equations in the time domain that is second order accurate in both space and time. The research presented here has involved the generalization of this procedure to higher order methods. High order methods are capable of yielding far more accurate numerical results for certain problems when compared to corresponding h-refined first order methods , and often times at a significant reduction in total computational cost. The first half of this dissertation presents the method as well as the necessary mathematics required for its derivation. The second half addresses the implementation of the method in a parallel computational environment, its validation using benchmark problems, and finally its use in large scale numerical simulations of electromagnetic transmission devices.

  19. Fabrication and Characterization of Nanoporous Niobia, and Nanotubular Tantala, Titania and Zirconia via Anodization

    Directory of Open Access Journals (Sweden)

    Sepideh Minagar

    2015-03-01

    Full Text Available Valve metals such as titanium (Ti, zirconium (Zr, niobium (Nb and tantalum (Ta that confer a stable oxide layer on their surfaces are commonly used as implant materials or alloying elements for titanium-based implants, due to their exceptional high corrosion resistance and excellent biocompatibility. The aim of this study was to investigate the bioactivity of the nanostructures of tantala (Ta2O5, niobia (Nb2O5, zirconia (ZrO2 and titania (TiO2 in accordance to their roughness and wettability. Therefore, four kinds of metal oxide nanoporous and nanotubular Ta2O5, Nb2O5, ZrO2 and TiO2 were fabricated via anodization. The nanosize distribution, morphology and the physical and chemical properties of the nanolayers and their surface energies and bioactivities were investigated using SEM-EDS, X-ray diffraction (XRD analysis and 3D profilometer. It was found that the nanoporous Ta2O5 exhibited an irregular porous structure, high roughness and high surface energy as compared to bare tantalum metal; and exhibited the most superior bioactivity after annealing among the four kinds of nanoporous structures. The nanoporous Nb2O5 showed a uniform porous structure and low roughness, but no bioactivity before annealing. Overall, the nanoporous and nanotubular layers of Ta2O5, Nb2O5, ZrO2 and TiO2 demonstrated promising potential for enhanced bioactivity to improve their biomedical application alone or to improve the usage in other biocompatible metal implants.

  20. High order aberrations calculation of a hexapole corrector using a differential algebra method

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Yongfeng, E-mail: yfkang@mail.xjtu.edu.cn [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Liu, Xing [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China); Zhao, Jingyi, E-mail: jingyi.zhao@foxmail.com [School of Science, Chang’an University, Xi’an 710064 (China); Tang, Tiantong [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China)

    2017-02-21

    A differential algebraic (DA) method is proved as an unusual and effective tool in numerical analysis. It implements conveniently differentiation up to arbitrary high order, based on the nonstandard analysis. In this paper, the differential algebra (DA) method has been employed to compute the high order aberrations up to the fifth order of a practical hexapole corrector including round lenses and hexapole lenses. The program has been developed and tested as well. The electro-magnetic fields of arbitrary point are obtained by local analytic expressions, then field potentials are transformed into new forms which can be operated in the DA calculation. In this paper, the geometric and chromatic aberrations up to fifth order of a practical hexapole corrector system are calculated by the developed program.

  1. High Order Numerical Simulation of Sound Generated by the Kirchhoff Vortex

    Science.gov (United States)

    Mueller, Bernhard; Yee, H. C.

    2001-01-01

    An improved high order finite difference method for low Mach number computational aeroacoustics (CAA) is described. The improvements involve the conditioning of the Euler equations in perturbation form to minimize numerical cancellation error, and the use of a stable non-dissipative sixth-order central spatial differencing for the interior points and third-order at the boundary points. The spatial difference operator satisfies the summation-by-parts property to guarantee strict stability for linear hyperbolic systems. Spurious high frequency oscillations are damped by a third-order characteristic-based filter. The objective of this paper is to apply these improvements in the simulation of sound generated by the Kirchhoff vortex.

  2. Broadband high-order mode pass filter based on mode conversion.

    Science.gov (United States)

    Ahmmed, Kazi Tanvir; Chan, Hau Ping; Li, Binghui

    2017-09-15

    We report a unique concept to implement a high-order mode pass filter using mode converters. Our proposed design method implements a high-order mode pass filter of any order, uses different mode converters available, and applies to a variety of planar lightwave circuit material platforms. We fabricate a broadband fundamental mode filter device using a Mach-Zehnder interferometer and Y-junctions to demonstrate our idea. The performance of the fabricated device is demonstrated experimentally in the wavelength range of 1.530-1.565 μm (C-band). This filter exhibits a simulated extinction ratio of 37 dB with an excess loss of 0.52 dB for the first-order mode transmission.

  3. Solving nonlinear, High-order partial differential equations using a high-performance isogeometric analysis framework

    KAUST Repository

    Cortes, Adriano Mauricio

    2014-01-01

    In this paper we present PetIGA, a high-performance implementation of Isogeometric Analysis built on top of PETSc. We show its use in solving nonlinear and time-dependent problems, such as phase-field models, by taking advantage of the high-continuity of the basis functions granted by the isogeometric framework. In this work, we focus on the Cahn-Hilliard equation and the phase-field crystal equation.

  4. Use of solid-state nanopores for sensing co-translocational deformation of nano-liposomes.

    Science.gov (United States)

    Goyal, Gaurav; Darvish, Armin; Kim, Min Jun

    2015-07-21

    Membrane deformation of nano-vesicles is crucial in many cellular processes such as virus entry into the host cell, membrane fusion, and endo- and exocytosis; however, studying the deformation of sub-100 nm soft vesicles is very challenging using the conventional techniques. In this paper, we report detecting co-translocational deformation of individual 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nano-liposomes using solid-state nanopores. Electrokinetic translocation through the nanopore caused the soft DOPC liposomes (85 nm diameter) to change their shape, which we attribute to the strong electric field strength and physical confinement inside the pore. The experiments were performed at varying transmembrane voltages and the deformation was observed to mount up with increasing applied voltage and followed an exponential trend. Numerical simulations were performed to simulate the concentrated electric field strength inside the nanopore and a field strength of 14 kV cm(-1) (at 600 mV applied voltage) was achieved at the pore center. The electric field strength inside the nanopore is much higher than the field strength known to cause deformation of 15-30 μm giant membrane vesicles. As a control, we also performed experiments with rigid polystyrene beads that did not show any deformation during translocation events, which further established our hypothesis of co-translocational deformation of liposomes. Our technique presents an innovative and high throughput means for investigating deformation behavior of soft nano-vesicles.

  5. A patch-clamp ASIC for nanopore-based DNA analysis.

    Science.gov (United States)

    Kim, Jungsuk; Maitra, Raj; Pedrotti, Kenneth D; Dunbar, William B

    2013-06-01

    In this paper, a fully integrated high-sensitivity patch-clamp system is proposed for single-molecule deoxyribonucleic acid (DNA) analysis using a nanopore sensor. This system is composed of two main blocks for amplification and compensation. The amplification block is composed of three stages: 1) a headstage, 2) a voltage-gain difference amplifier, and 3) a track-and-hold circuit, that amplify a minute ionic current variation sensed by the nanopore while the compensation block avoids the headstage saturation caused by the input parasitic capacitances during sensing. By employing design techniques novel for this application, such as an instrumentation--amplifier topology and a compensation switch, we minimize the deleterious effects of the input-offset voltage and the input parasitic capacitances while attaining hardware simplicity. This system is fabricated in a 0.35 μm 4M2P CMOS process and is demonstrated using an α-hemolysin protein nanopore for detection of individual molecules of single-stranded DNA that pass through the 1.5 nm-diameter pore. In future work, the refined system will functionalize single and multiple solid-state nanopores formed in integrated microfluidic devices for advanced DNA analysis, in scientific and diagnostic applications.

  6. Control of shape and material composition of solid-state nanopores.

    Science.gov (United States)

    Wu, Meng-Yue; Smeets, Ralph M M; Zandbergen, Mathijs; Ziese, Ulrike; Krapf, Diego; Batson, Philip E; Dekker, Nynke H; Dekker, Cees; Zandbergen, Henny W

    2009-01-01

    Solid-state nanopores fabricated by a high-intensity electron beam in ceramic membranes can be fine-tuned on three-dimensional geometry and composition by choice of materials and beam sculpting conditions. For similar beam conditions, 8 nm diameter nanopores fabricated in membranes containing SiO(2) show large depletion areas (70 nm in radius) with small sidewall angles (55 degrees ), whereas those made in SiN membranes show small depletion areas (40 nm) with larger sidewall angles (75 degrees ). Three-dimensional electron tomograms of nanopores fabricated in a SiO(2)/SiN/SiO(2) membrane show a biconical shape with symmetric top and bottom and indicate a mixing of SiN and SiO(2) layers up to 30 nm from the edge of nanopore, with Si-rich particles throughout the membrane. Electron-energy-loss spectroscopy (EELS) reveals that the oxygen/nitrogen ratio near the pore depends on the beam sculpting conditions.

  7. Macroscopic nanoporous graphene membranes for molecular-sieving-based gas separation

    Science.gov (United States)

    Boutilier, Michael; Karnik, Rohit; Hadjiconstantinou, Nicolas

    2016-11-01

    Nanoporous graphene membranes have the potential to exceed permeance and selectivity limits of existing gas separation membranes. This is made possible by the atomic thickness of the material, which can support sub-nanometer pores that enable molecular sieving while presenting low resistance to permeate flow. The feasibility of gas separation by graphene nanopores has been demonstrated experimentally on micron-scale areas of graphene. However, scaling up to macroscopic membrane areas presents significant challenges, including graphene imperfections and control of the selective nanopore size distribution across large areas. Towards this goal, gas permeance experiments are conducted on single and few layer graphene membranes to understand leakage pathways and a model is developed to predict conditions under which molecular sieving can occur in macroscopic membranes. Approaches to seal or mitigate the effects of micron and nanometer scale defects in graphene are investigated and methods of creating a high density of selectively permeable nanopores are explored. Experimental results demonstrating separation ratios exceeding the Knudsen effusion limit, indicating molecular sieving in agreement with the model predictions, are presented and discussed.

  8. Nanoporous carbons derived from binary carbides and their optimization for hydrogen storage

    Science.gov (United States)

    Dash, Ranjan Kumar

    On-board hydrogen storage is one of the major hurdles for success of hydrogen economy. Hydrogen storage using physisorption technique demands highly porous materials. Carbide derived carbons (CDC), a new class of porous carbons produced by thermo chemical etching of metal atoms from carbides were selected as a method for producing highly porous material for hydrogen storage. In order to synthesize tunable nanoporous carbon and to establish a structure-property relation between initial metal carbide and resultant nanoporous carbon, CDCs were synthesized from four metal carbides, two that have uniform carbon to carbon distance in the lattice structure (ZrC, TiC and SiC) and one that has a non-uniform carbon distribution in the lattice (B4C). It was shown that a uniform distribution of carbon atoms in the carbide is important for obtaining a narrow pore size distribution (PSD). CDC derived from B 4C had a relatively broad PSD and contained mesopores even at the lowest synthesis temperature, while the CDC produced from SiC maintained a narrow PSD even at the synthesis temperature of 1200°C. CDC produced from ZrC and TiC has a narrow PSD at low synthesis temperature and pores gets wider at higher temperatures. Comparison of CDCs produced from ZrC, TiC and B 4C shows that CDCs produced from ZrC and TiC show a lower degree of ordering than that from B4C at high temperatures. Unlike CDCs produced from ZrC and TiC, the PSD of CDCs from B4C does not change appreciably in the 600-1200°C range. CDCs produced from ZrC and TiC can have both narrowly distributed micropores (pores smaller than 2 nm) and mesopores (pores larger than 2 nm), depending on synthesis temperature. In this work, it is demonstrated that porosity of CDC can be fine tuned with a high accuracy by using different starting carbides and varying the synthesis temperatures. This is very important in many applications of porous carbon, especially for gas storage. CDC from ZrC, TiC, B4C and SiC resulted in a

  9. Heat transport in bulk/nanoporous/bulk silicon devices

    Energy Technology Data Exchange (ETDEWEB)

    Criado-Sancho, M. [Departamento de Ciencias y Técnicas Físicoquimicas, Facultad de Ciencias, UNED, Senda del Rey 9, 20040 Madrid (Spain); Jou, D., E-mail: David.Jou@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Institut d' Estudis Catalans, Carme 47, 08001 Barcelona, Catalonia (Spain)

    2013-02-04

    We study heat transport in bulk/nanoporous/bulk silicon devices; we show that, despite bulk/nanoporous devices may act as thermal rectifiers, the non-linear aspects of their joint thermal conductance are not strong enough to lead to a negative differential thermal resistance, necessary to allow bulk/nanoporous/bulk Si devices to act as thermal transistors. Furthermore, we explicitly study the effective thermal conductivity of the mentioned devices for several temperatures, geometries, porosities, and pore size.

  10. Study of polymer molecules and conformations with a nanopore

    Energy Technology Data Exchange (ETDEWEB)

    Golovchenko, Jene A.; Li, Jiali; Stein, Derek; Gershow, Marc H.

    2013-03-12

    The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

  11. Study of polymer molecules and conformations with a nanopore

    Energy Technology Data Exchange (ETDEWEB)

    Golovchenko, Jene A; Li, Jiali; Stein, Derek; Gershow, Marc H

    2015-03-03

    The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

  12. Study of polymer molecules and conformations with a nanopore

    Science.gov (United States)

    Golovchenko, Jene A.; Li, Jiali; Stein, Derek; Gershow, Marc H.

    2010-12-07

    The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

  13. Stepwise Nanopore Evolution in One-Dimensional Nanostructures

    KAUST Repository

    Choi, Jang Wook

    2010-04-14

    We report that established simple lithium (Li) ion battery cycles can be used to produce nanopores inside various useful one-dimensional (1D) nanostructures such as zinc oxide, silicon, and silver nanowires. Moreover, porosities of these 1D nanomaterials can be controlled in a stepwise manner by the number of Li-battery cycles. Subsequent pore characterization at the end of each cycle allows us to obtain detailed snapshots of the distinct pore evolution properties in each material due to their different atomic diffusion rates and types of chemical bonds. Also, this stepwise characterization led us to the first observation of pore size increases during cycling, which can be interpreted as a similar phenomenon to Ostwald ripening in analogous nanoparticle cases. Finally, we take advantage of the unique combination of nanoporosity and 1D materials and demonstrate nanoporous silicon nanowires (poSiNWs) as excellent supercapacitor (SC) electrodes in high power operations compared to existing devices with activated carbon. © 2010 American Chemical Society.

  14. Time implicit high-order discontinuous galerkin method with reduced evaluation cost

    OpenAIRE

    Renac, Florent; Marmignon, Claude; Coquel, Frédéric

    2012-01-01

    International audience; Abstract: An efficient and robust time integration procedure for a high-order discontinuous Galerkin method is introduced for solving nonlinear second-order partial differential equations. The time discretization is based on an explicit formulation for the hyperbolic term and an implicit formulation for the parabolic term. The procedure uses an iterative algorithm with reduced evaluation cost. The size of the linear system to be solved is greatly reduced thanks to par...

  15. High temperature color conductivity at next-to-leading log order

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Peter; Yaffe, Laurence G.

    2000-12-15

    The non-Abelian analogue of electrical conductivity at high temperature has previously been known only at leading logarithmic order -- that is, neglecting effects suppressed only by an inverse logarithm of the gauge coupling. We calculate the first sub-leading correction. This has immediate application to improving, to next-to-leading log order, both effective theories of non-perturbative color dynamics, and calculations of the hot electroweak baryon number violation rate.

  16. Entropy Viscosity Method for High-Order Approximations of Conservation Laws

    KAUST Repository

    Guermond, J. L.

    2010-09-17

    A stabilization technique for conservation laws is presented. It introduces in the governing equations a nonlinear dissipation function of the residual of the associated entropy equation and bounded from above by a first order viscous term. Different two-dimensional test cases are simulated - a 2D Burgers problem, the "KPP rotating wave" and the Euler system - using high order methods: spectral elements or Fourier expansions. Details on the tuning of the parameters controlling the entropy viscosity are given. © 2011 Springer.

  17. Calculation and manipulation of the chirp rates of high-order harmonics

    OpenAIRE

    Murakami, M.; Mauritsson, Johan; L'Huillier, Anne; Schafer, KJ; Gaarde, Mette

    2005-01-01

    We calculate the linear chirp rates of high-order harmonics in argon, generated by intense, 810 nm laser pulses, and explore the dependence of the chirp rate on harmonic order, driving laser intensity, and pulse duration. By using a time-frequency representation of the harmonic fields we can identify several different linear chirp contributions. to the plateau harmonics. Our results, which are based on numerical integration of the time-dependent Schrodinger equation, are in good agreement wit...

  18. A high-order q-difference equation for q-Hahn multiple orthogonal polynomials

    DEFF Research Database (Denmark)

    Arvesú, J.; Esposito, Chiara

    2012-01-01

    A high-order linear q-difference equation with polynomial coefficients having q-Hahn multiple orthogonal polynomials as eigenfunctions is given. The order of the equation coincides with the number of orthogonality conditions that these polynomials satisfy. Some limiting situations when are studie....... Indeed, the difference equation for Hahn multiple orthogonal polynomials given in Lee [J. Approx. Theory (2007), ), doi: 10.1016/j.jat.2007.06.002] is obtained as a limiting case....

  19. Tailoring High Order Time Discretizations for Use with Spatial Discretizations of Hyperbolic PDEs

    Science.gov (United States)

    2015-05-19

    multi- ple steps and multiple stages have the potential to combine the properties of multistep and Runge–Kutta methods, and so provide an advantage over...Duration of Grant Sigal Gottlieb, Professor of Mathematics, UMass Dartmouth. Daniel Higgs , Graduate Student, UMass Dartmouth. Zachary Grant, Undergraduate...Grant, and D. Higgs , “Optimal Explicit Strong Stability Preserving Runge– Kutta Methods with High Linear Order and optimal Nonlinear Order.” Accepted

  20. High-Order Hyperbolic Residual-Distribution Schemes on Arbitrary Triangular Grids

    Science.gov (United States)

    Mazaheri, Alireza; Nishikawa, Hiroaki

    2015-01-01

    In this paper, we construct high-order hyperbolic residual-distribution schemes for general advection-diffusion problems on arbitrary triangular grids. We demonstrate that the second-order accuracy of the hyperbolic schemes can be greatly improved by requiring the scheme to preserve exact quadratic solutions. We also show that the improved second-order scheme can be easily extended to third-order by further requiring the exactness for cubic solutions. We construct these schemes based on the LDA and the SUPG methodology formulated in the framework of the residual-distribution method. For both second- and third-order-schemes, we construct a fully implicit solver by the exact residual Jacobian of the second-order scheme, and demonstrate rapid convergence of 10-15 iterations to reduce the residuals by 10 orders of magnitude. We demonstrate also that these schemes can be constructed based on a separate treatment of the advective and diffusive terms, which paves the way for the construction of hyperbolic residual-distribution schemes for the compressible Navier-Stokes equations. Numerical results show that these schemes produce exceptionally accurate and smooth solution gradients on highly skewed and anisotropic triangular grids, including curved boundary problems, using linear elements. We also present Fourier analysis performed on the constructed linear system and show that an under-relaxation parameter is needed for stabilization of Gauss-Seidel relaxation.

  1. Simulation of vesicle using level set method solved by high order finite element

    Directory of Open Access Journals (Sweden)

    Doyeux Vincent

    2013-01-01

    Full Text Available We present a numerical method to simulate vesicles in fluid flows. This method consists of writing all the properties of the membrane as interfacial forces between two fluids. The main advantage of this approach is that the vesicle and the fluid models may be decoupled easily. A level set method has been implemented to track the interface. Finite element discretization has been used with arbitrarily high order polynomial approximation. Several polynomial orders have been tested in order to get a better accuracy. A validation on equilibrium shapes and “tank treading” motion of vesicle have been presented.

  2. Multidimensional Vlasov–Poisson Simulations with High-order Monotonicity- and Positivity-preserving Schemes

    Science.gov (United States)

    Tanaka, Satoshi; Yoshikawa, Kohji; Minoshima, Takashi; Yoshida, Naoki

    2017-11-01

    We develop new numerical schemes for Vlasov–Poisson equations with high-order accuracy. Our methods are based on a spatially monotonicity-preserving (MP) scheme and are modified suitably so that the positivity of the distribution function is also preserved. We adopt an efficient semi-Lagrangian time integration scheme that is more accurate and computationally less expensive than the three-stage TVD Runge–Kutta integration. We apply our spatially fifth- and seventh-order schemes to a suite of simulations of collisionless self-gravitating systems and electrostatic plasma simulations, including linear and nonlinear Landau damping in one dimension and Vlasov–Poisson simulations in a six-dimensional phase space. The high-order schemes achieve a significantly improved accuracy in comparison with the third-order positive-flux-conserved scheme adopted in our previous study. With the semi-Lagrangian time integration, the computational cost of our high-order schemes does not significantly increase, but remains roughly the same as that of the third-order scheme. Vlasov–Poisson simulations on {128}3× {128}3 mesh grids have been successfully performed on a massively parallel computer.

  3. Development of a three-dimensional high-order strand-grids approach

    Science.gov (United States)

    Tong, Oisin

    Development of a novel high-order flux correction method on strand grids is presented. The method uses a combination of flux correction in the unstructured plane and summation-by-parts operators in the strand direction to achieve high-fidelity solutions. Low-order truncation errors are cancelled with accurate flux and solution gradients in the flux correction method, thereby achieving a formal order of accuracy of 3, although higher orders are often obtained, especially for highly viscous flows. In this work, the scheme is extended to high-Reynolds number computations in both two and three dimensions. Turbulence closure is achieved with a robust version of the Spalart-Allmaras turbulence model that accommodates negative values of the turbulence working variable, and the Menter SST turbulence model, which blends the k-epsilon and k-o turbulence models for better accuracy. A major advantage of this high-order formulation is the ability to implement traditional finite volume-like limiters to cleanly capture shocked and discontinuous flows. In this work, this approach is explored via a symmetric limited positive (SLIP) limiter. Extensive verification and validation is conducted in two and three dimensions to determine the accuracy and fidelity of the scheme for a number of different cases. Verification studies show that the scheme achieves better than third order accuracy for low and high-Reynolds number flows. Cost studies show that in three-dimensions, the third-order flux correction scheme requires only 30% more walltime than a traditional second-order scheme on strand grids to achieve the same level of convergence. In order to overcome meshing issues at sharp corners and other small-scale features, a unique approach to traditional geometry, coined "asymptotic geometry," is explored. Asymptotic geometry is achieved by filtering out small-scale features in a level set domain through min/max flow. This approach is combined with a curvature based strand shortening

  4. Control of ionic transport through gated single conical nanopores.

    Science.gov (United States)

    Kalman, Eric B; Sudre, Olivier; Vlassiouk, Ivan; Siwy, Zuzanna S

    2009-05-01

    Control of ionic transport through nanoporous systems is a topic of scientific interest for the ability to create new devices that are applicable for ions and molecules in water solutions. We show the preparation of an ionic transistor based on single conical nanopores in polymer films with an insulated gold thin film "gate." By changing the electric potential applied to the "gate," the current through the device can be changed from the rectifying behavior of a typical conical nanopore to the almost linear behavior seen in cylindrical nanopores. The mechanism for this change in transport behavior is thought to be the enhancement of concentration polarization induced by the gate.

  5. Fabrication of cellulose self-assemblies and high-strength ordered cellulose films.

    Science.gov (United States)

    Yuan, Zaiwu; Zhang, Jingjing; Jiang, Anning; Lv, Wenting; Wang, Yuewen; Geng, Hongjuan; Wang, Jin; Qin, Menghua

    2015-03-06

    Based on the formation of cellulose hydrogels in NaOH/urea aqueous solvent media, cellulose self-assembly precursor is acquired. It is proved that the water uptake capability of the cellulose hydrogels depends highly on the cross-link degree (CLD) of cellulose. With varying CLD and concentration of cellulose, a variety of morphologies of cellulose self-assemblies, including sheets with perfect morphology, high-aspect-ratio fibers, and disorganized segments and network, are formed through evaporation. Furthermore, cellulose films are fabricated by diecasting and evaporating the cellulose hydrogels, resulting in a 3D-ordered structure of closely stacking of cellulose sheets. The mechanical test indicates both tensile strength and flexibility of the cellulose films are greatly improved, which is attributed to the formation of the orderly stacking of cellulose sheets. The study is expected to lay an important foundation on the preparation of ordered and high-strength cellulose materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. High-order harmonic generation from polyatomic molecules including nuclear motion and a nuclear modes analysis

    DEFF Research Database (Denmark)

    Madsen, Christian Bruun; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2010-01-01

    as a nuclear correlation function. We express the nuclear correlation function in terms of Franck-Condon factors, which allows us to decompose nuclear motion into modes and identify the modes that are dominant in the high-order harmonic generation process. We show results for the isotopes CH4 and CD4......We present a generic approach for treating the effect of nuclear motion in high-order harmonic generation from polyatomic molecules. Our procedure relies on a separation of nuclear and electron dynamics where we account for the electronic part using the Lewenstein model and nuclear motion enters...... and thereby provide direct theoretical support for a recent experiment [S. Baker et al., Science 312, 424 (2006)] that uses high-order harmonic generation to probe the ultrafast structural nuclear rearrangement of ionized methane....

  7. High-order conservative discretizations for some cases of the rigid body motion

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, Roman [Department of Mathematics, University of Bergen, Johannes Brunsgate 12, 5008 Bergen (Norway)], E-mail: roman.kozlov@mi.uib.no

    2008-12-22

    Modified vector fields can be used to construct high-order structure-preserving numerical integrators for ordinary differential equations. In the present Letter we consider high-order integrators based on the implicit midpoint rule, which conserve quadratic first integrals. It is shown that these integrators are particularly suitable for the rigid body motion with an additional quadratic first integral. In this case high-order integrators preserve all four first integrals of motion. The approach is illustrated on the Lagrange top (a rotationally symmetric rigid body with a fixed point on the symmetry axis). The equations of motion are considered in the space fixed frame because in this frame Lagrange top admits a neat description. The Lagrange top motion includes the spherical pendulum and the planar pendulum, which swings in a vertical plane, as particular cases.

  8. Ab initio multiscale simulation of high-order harmonic generation in solids

    Science.gov (United States)

    Floss, Isabella; Lemell, Christoph; Wachter, Georg; Smejkal, Valerie; Sato, Shunsuke A.; Tong, Xiao-Min; Yabana, Kazuhiro; Burgdörfer, Joachim

    2018-01-01

    High-order-harmonic generation by a highly nonlinear interaction of infrared laser fields with matter allows for the generation of attosecond pulses in the XUV spectral regime. This process, well established for atoms, has been recently extended to the condensed phase. Remarkably well-pronounced harmonics up to order ˜30 have been observed for dielectrics. We establish a route toward an ab initio multiscale simulation of solid-state high-order-harmonic generation. We find that mesoscopic effects of the extended system, in particular the realistic sampling of the entire Brillouin zone, the pulse propagation in the dense medium, and the inhomogeneous illumination of the crystal, have a strong effect on the harmonic spectra. Our results provide an explanation for the formation of clean harmonics and have implications for a wide range of nonlinear optical processes in dense media.

  9. Giant Faraday Rotation of High-Order Plasmonic Modes in Graphene-Covered Nanowires.

    Science.gov (United States)

    Kuzmin, Dmitry A; Bychkov, Igor V; Shavrov, Vladimir G; Temnov, Vasily V

    2016-07-13

    Plasmonic Faraday rotation in nanowires manifests itself in the rotation of the spatial intensity distribution of high-order surface plasmon polariton (SPP) modes around the nanowire axis. Here we predict theoretically the giant Faraday rotation for SPPs propagating on graphene-coated magneto-optically active nanowires. Upon the reversal of the external magnetic field pointing along the nanowire axis some high-order plasmonic modes may be rotated by up to ∼100° on the length scale of about 500 nm at mid-infrared frequencies. Tuning the carrier concentration in graphene by chemical doping or gate voltage allows for controlling SPP-properties and notably the rotation angle of high-order azimuthal modes. Our results open the door to novel plasmonic applications ranging from nanowire-based Faraday isolators to the magnetic control in quantum-optical applications.

  10. Highly ordered three-dimensional macroporous carbon spheres for determination of heavy metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuxiao; Zhang, Jianming [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Huang, Hui [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Highly ordered three dimensional macroporous carbon spheres (MPCSs) were prepared. Black-Right-Pointing-Pointer MPCS was covalently modified by cysteine (MPCS-CO-Cys). Black-Right-Pointing-Pointer MPCS-CO-Cys was first time used in electrochemical detection of heavy metal ions. Black-Right-Pointing-Pointer Heavy metal ions such as Pb{sup 2+} and Cd{sup 2+} can be simultaneously determined. -- Abstract: An effective voltammetric method for detection of trace heavy metal ions using chemically modified highly ordered three dimensional macroporous carbon spheres electrode surfaces is described. The highly ordered three dimensional macroporous carbon spheres were prepared by carbonization of glucose in silica crystal bead template, followed by removal of the template. The highly ordered three dimensional macroporous carbon spheres were covalently modified by cysteine, an amino acid with high affinities towards some heavy metals. The materials were characterized by physical adsorption of nitrogen, scanning electron microscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. High sensitivity was exhibited when this material was used in electrochemical detection (square wave anodic stripping voltammetry) of heavy metal ions due to the porous structure. And the potential application for simultaneous detection of heavy metal ions was also investigated.

  11. Overlay control methodology comparison: field-by-field and high-order methods

    Science.gov (United States)

    Huang, Chun-Yen; Chiu, Chui-Fu; Wu, Wen-Bin; Shih, Chiang-Lin; Huang, Chin-Chou Kevin; Huang, Healthy; Choi, DongSub; Pierson, Bill; Robinson, John C.

    2012-03-01

    Overlay control in advanced integrated circuit (IC) manufacturing is becoming one of the leading lithographic challenges in the 3x and 2x nm process nodes. Production overlay control can no longer meet the stringent emerging requirements based on linear composite wafer and field models with sampling of 10 to 20 fields and 4 to 5 sites per field, which was the industry standard for many years. Methods that have emerged include overlay metrology in many or all fields, including the high order field model method called high order control (HOC), and field by field control (FxFc) methods also called correction per exposure. The HOC and FxFc methods were initially introduced as relatively infrequent scanner qualification activities meant to supplement linear production schemes. More recently, however, it is clear that production control is also requiring intense sampling, similar high order and FxFc methods. The added control benefits of high order and FxFc overlay methods need to be balanced with the increased metrology requirements, however, without putting material at risk. Of critical importance is the proper control of edge fields, which requires intensive sampling in order to minimize signatures. In this study we compare various methods of overlay control including the performance levels that can be achieved.

  12. Nucleation of ordered solid phases of proteins via a disordered high-density state: Phenomenological approach

    Science.gov (United States)

    Pan, Weichun; Kolomeisky, Anatoly B.; Vekilov, Peter G.

    2005-05-01

    Nucleation of ordered solid phases of proteins triggers numerous phenomena in laboratory, industry, and in healthy and sick organisms. Recent simulations and experiments with protein crystals suggest that the formation of an ordered crystalline nucleus is preceded by a disordered high-density cluster, akin to a droplet of high-density liquid that has been observed with some proteins; this mechanism allowed a qualitative explanation of recorded complex nucleation kinetics curves. Here, we present a simple phenomenological theory that takes into account intermediate high-density metastable states in the nucleation process. Nucleation rate data at varying temperature and protein concentration are reproduced with high fidelity using literature values of the thermodynamic and kinetic parameters of the system. Our calculations show that the growth rate of the near-critical and supercritical ordered clusters within the dense intermediate is a major factor for the overall nucleation rate. This highlights the role of viscosity within the dense intermediate for the formation of the ordered nucleus. The model provides an understanding of the action of additives that delay or accelerate nucleation and presents a framework within which the nucleation of other ordered protein solid phases, e.g., the sickle cell hemoglobin polymers, can be analyzed.

  13. Conversion of Isoprenoid Oil by Catalytic Cracking and Hydrocracking over Nanoporous Hybrid Catalysts

    OpenAIRE

    Kimura, Toshiyuki; Liu, Chen; Li, Xiaohong; Maekawa, Takaaki; Asaoka, Sachio

    2012-01-01

    In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of m...

  14. An improved 2D MoF method by using high order derivatives

    Science.gov (United States)

    Chen, Xiang; Zhang, Xiong

    2017-11-01

    The MoF (Moment of Fluid) method is one of the most accurate approaches among various interface reconstruction algorithms. Alike other second order methods, the MoF method needs to solve an implicit optimization problem to obtain the optimal approximate interface, so an iteration process is inevitable under most circumstances. In order to solve the optimization efficiently, the properties of the objective function are worthy of studying. In 2D problems, the first order derivative has been deduced and applied in the previous researches. In this paper, the high order derivatives of the objective function are deduced on the convex polygon. We show that the nth (n ≥ 2) order derivatives are discontinuous, and the number of the discontinuous points is two times the number of the polygon edge. A rotation algorithm is proposed to successively calculate these discontinuous points, thus the target interval where the optimal solution is located can be determined. Since the high order derivatives of the objective function are continuous in the target interval, the iteration schemes based on high order derivatives can be used to improve the convergence rate. Moreover, when iterating in the target interval, the value of objective function and its derivatives can be directly updated without explicitly solving the volume conservation equation. The direct update makes a further improvement of the efficiency especially when the number of edges of the polygon is increasing. The Halley's method, which is based on the first three order derivatives, is applied as the iteration scheme in this paper and the numerical results indicate that the CPU time is about half of the previous method on the quadrilateral cell and is about one sixth on the decagon cell.

  15. Learning High-Order Filters for Efficient Blind Deconvolution of Document Photographs

    KAUST Repository

    Xiao, Lei

    2016-09-16

    Photographs of text documents taken by hand-held cameras can be easily degraded by camera motion during exposure. In this paper, we propose a new method for blind deconvolution of document images. Observing that document images are usually dominated by small-scale high-order structures, we propose to learn a multi-scale, interleaved cascade of shrinkage fields model, which contains a series of high-order filters to facilitate joint recovery of blur kernel and latent image. With extensive experiments, we show that our method produces high quality results and is highly efficient at the same time, making it a practical choice for deblurring high resolution text images captured by modern mobile devices. © Springer International Publishing AG 2016.

  16. Neurodynamics-Based Robust Pole Assignment for High-Order Descriptor Systems.

    Science.gov (United States)

    Le, Xinyi; Wang, Jun

    2015-11-01

    In this paper, a neurodynamic optimization approach is proposed for synthesizing high-order descriptor linear systems with state feedback control via robust pole assignment. With a new robustness measure serving as the objective function, the robust eigenstructure assignment problem is formulated as a pseudoconvex optimization problem. A neurodynamic optimization approach is applied and shown to be capable of maximizing the robust stability margin for high-order singular systems with guaranteed optimality and exact pole assignment. Two numerical examples and vehicle vibration control application are discussed to substantiate the efficacy of the proposed approach.

  17. Development of high-order harmonic focusing system based on ellipsoidal mirror

    Energy Technology Data Exchange (ETDEWEB)

    Motoyama, H.; Takei, Y.; Kume, T.; Egawa, S.; Mimura, H., E-mail: mimura@edm.t.u-tokyo.ac.jp [Department of Precision Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkuyo-ku, Tokyo 113-8656 (Japan); Sato, T.; Iwasaki, A.; Yamanouchi, K. [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hiraguri, K.; Hashizume, H. [Natsume Optical Corp., 3461 Kamichaya, Kanae, Iida, Nagano 395-0808 (Japan)

    2016-05-15

    We have developed a focusing system for extreme ultraviolet light produced by high-order harmonic generation. An ellipsoidal mirror with a precise surface shape was fabricated and installed into the focusing system. A rigid mirror manipulator and a beam profiler were employed to perform precise and stable mirror alignment. As a demonstration of the focusing performance, high-order harmonics in the wavelength range of 13.5–19.5 nm were successfully focused into a 2.4 × 2.3 μm{sup 2} spot.

  18. High-Order Entropy Stable Finite Difference Schemes for Nonlinear Conservation Laws: Finite Domains

    Science.gov (United States)

    Fisher, Travis C.; Carpenter, Mark H.

    2013-01-01

    Developing stable and robust high-order finite difference schemes requires mathematical formalism and appropriate methods of analysis. In this work, nonlinear entropy stability is used to derive provably stable high-order finite difference methods with formal boundary closures for conservation laws. Particular emphasis is placed on the entropy stability of the compressible Navier-Stokes equations. A newly derived entropy stable weighted essentially non-oscillatory finite difference method is used to simulate problems with shocks and a conservative, entropy stable, narrow-stencil finite difference approach is used to approximate viscous terms.

  19. A ROBUST ARBITRARILY HIGH ORDER TRANSPORT METHOD OF THE CHARACTERISTIC TYPE FOR UNSTRUCTURED TETRAHEDRAL GRIDS

    Energy Technology Data Exchange (ETDEWEB)

    R. M. Ferrer; Y. Y. Azmy

    2009-05-01

    We present a robust arbitrarily high order transport method of the characteristic type for unstructured tetrahedral grids. Previously encountered difficulties have been addressed through the reformulation of the method based on coordinate transformations, evaluation of the moments balance relation as a linear system of equations involving the expansion coefficients of the projected basis, and the asymptotic expansion of the integral kernels in the thin cell limit. The proper choice of basis functions for the high-order spatial expansion of the solution is discussed and its effect on problems involving scattering discussed. Numerical tests are presented to illustrate the beneficial effect of these improvements, and the improved robustness they yield.

  20. Nodal DG-FEM solution of high-order Boussinesq-type equations

    DEFF Research Database (Denmark)

    Engsig-Karup, Allan Peter; Hesthaven, Jan S.; Bingham, Harry B.

    2006-01-01

    We present a discontinuous Galerkin finite element method (DG-FEM) solution to a set of high-order Boussinesq-type equations for modelling highly nonlinear and dispersive water waves in one and two horizontal dimensions. The continuous equations are discretized using nodal polynomial basis...... and convergence of the model with both h (grid size) and p (order) refinement are verified for the linearized equations, and calculations are provided for two nonlinear test cases in one horizontal dimension: harmonic generation over a submerged bar; and reflection of a steep solitary wave from a vertical wall...

  1. A high-order statistical tensor based algorithm for anomaly detection in hyperspectral imagery.

    Science.gov (United States)

    Geng, Xiurui; Sun, Kang; Ji, Luyan; Zhao, Yongchao

    2014-11-04

    Recently, high-order statistics have received more and more interest in the field of hyperspectral anomaly detection. However, most of the existing high-order statistics based anomaly detection methods require stepwise iterations since they are the direct applications of blind source separation. Moreover, these methods usually produce multiple detection maps rather than a single anomaly distribution image. In this study, we exploit the concept of coskewness tensor and propose a new anomaly detection method, which is called COSD (coskewness detector). COSD does not need iteration and can produce single detection map. The experiments based on both simulated and real hyperspectral data sets verify the effectiveness of our algorithm.

  2. High temperature sensing using higher-order-mode rejected sapphire-crystal fiber gratings

    Science.gov (United States)

    Zhan, Chun; Kim, Jae Hun; Lee, Jon; Yin, Stuart; Ruffin, Paul; Luo, Claire

    2007-09-01

    In this paper, we report the fabrication of higher-order-mode rejected fiber Bragg gratings (FBGs) in sapphire crystal fiber using infrared (IR) femtosecond laser illumination. The grating is tested in high temperature furnace up to 1600 degree Celsius. As sapphire fiber is only available as highly multimode fiber, a scheme to filter out higher order modes in favor for the fundamental mode is theoretically evaluated and experimentally demonstrated. The approach is to use an ultra thin sapphire crystal fiber (60 micron in diameter) to decrease the number of modes. The small diameter fiber also enables bending the fiber to certain radius which is carefully chosen to provide low loss for the fundamental mode LP01 and high loss for the other high-order modes. After bending, less-than-2-nm resonant peak bandwidth is achieved. The grating spectrum is improved, and higher resolution sensing measurement can be achieved. This mode filtering method is very easy to implement. Furthermore, the sapphire fiber is sealed with hi-purity alumina ceramic cement inside a flexible high temperature titanium tube, and the highly flexible titanium tube offers a robust packaging to sapphire fiber. Our high temperature sapphire grating sensor is very promising in extremely high temperature sensing application.

  3. Quantifying similarity of pore-geometry in nanoporous materials

    Science.gov (United States)

    Lee, Yongjin; Barthel, Senja D.; Dłotko, Paweł; Moosavi, S. Mohamad; Hess, Kathryn; Smit, Berend

    2017-05-01

    In most applications of nanoporous materials the pore structure is as important as the chemical composition as a determinant of performance. For example, one can alter performance in applications like carbon capture or methane storage by orders of magnitude by only modifying the pore structure. For these applications it is therefore important to identify the optimal pore geometry and use this information to find similar materials. However, the mathematical language and tools to identify materials with similar pore structures, but different composition, has been lacking. We develop a pore recognition approach to quantify similarity of pore structures and classify them using topological data analysis. This allows us to identify materials with similar pore geometries, and to screen for materials that are similar to given top-performing structures. Using methane storage as a case study, we also show that materials can be divided into topologically distinct classes requiring different optimization strategies.

  4. A nonlinear filter for high order discontinuous Galerkin discretizations with discontinuity resolution within the cell

    Science.gov (United States)

    Panourgias, Konstantinos T.; Ekaterinaris, John A.

    2016-12-01

    The nonlinear filter introduced by Yee et al. (1999) [27] and extensively used in the development of low dissipative well-balanced high order accurate finite-difference schemes is adapted to the finite element context of discontinuous Galerkin (DG) discretizations. The filter operator is constructed in the canonical computational domain for the standard cubical element where it is applied to the computed conservative variables in a direction per direction basis. Filtering becomes possible for all element types in unstructured meshes using collapsed coordinate transformations. The performance of the proposed nonlinear filter for DG discretizations is demonstrated and evaluated for different orders of expansions for one-dimensional and multidimensional problems with exact solutions. It is shown that for higher order discretizations discontinuity resolution within the cell is achieved and the design order of accuracy is preserved. The filter is applied for a number of standard inviscid flow test problems including strong shocks interactions to demonstrate that the proposed dissipative mechanism for DG discretizations yields superior results compared to the results obtained with the total variation bounded (TVB) limiter and high-order hierarchical limiting. The proposed approach is suitable for p-adaptivity in order to locally enhance resolution of three-dimensional flow simulations that include discontinuities and complex flow features.

  5. A high-order spatial filter for a cubed-sphere spectral element model

    Science.gov (United States)

    Kang, Hyun-Gyu; Cheong, Hyeong-Bin

    2017-04-01

    A high-order spatial filter is developed for the spectral-element-method dynamical core on the cubed-sphere grid which employs the Gauss-Lobatto Lagrange interpolating polynomials (GLLIP) as orthogonal basis functions. The filter equation is the high-order Helmholtz equation which corresponds to the implicit time-differencing of a diffusion equation employing the high-order Laplacian. The Laplacian operator is discretized within a cell which is a building block of the cubed sphere grid and consists of the Gauss-Lobatto grid. When discretizing a high-order Laplacian, due to the requirement of C0 continuity along the cell boundaries the grid-points in neighboring cells should be used for the target cell: The number of neighboring cells is nearly quadratically proportional to the filter order. Discrete Helmholtz equation yields a huge-sized and highly sparse matrix equation whose size is N*N with N the number of total grid points on the globe. The number of nonzero entries is also almost in quadratic proportion to the filter order. Filtering is accomplished by solving the huge-matrix equation. While requiring a significant computing time, the solution of global matrix provides the filtered field free of discontinuity along the cell boundaries. To achieve the computational efficiency and the accuracy at the same time, the solution of the matrix equation was obtained by only accounting for the finite number of adjacent cells. This is called as a local-domain filter. It was shown that to remove the numerical noise near the grid-scale, inclusion of 5*5 cells for the local-domain filter was found sufficient, giving the same accuracy as that obtained by global domain solution while reducing the computing time to a considerably lower level. The high-order filter was evaluated using the standard test cases including the baroclinic instability of the zonal flow. Results indicated that the filter performs better on the removal of grid-scale numerical noises than the explicit

  6. Cell-centered high-order hyperbolic finite volume method for diffusion equation on unstructured grids

    Science.gov (United States)

    Lee, Euntaek; Ahn, Hyung Taek; Luo, Hong

    2018-02-01

    We apply a hyperbolic cell-centered finite volume method to solve a steady diffusion equation on unstructured meshes. This method, originally proposed by Nishikawa using a node-centered finite volume method, reformulates the elliptic nature of viscous fluxes into a set of augmented equations that makes the entire system hyperbolic. We introduce an efficient and accurate solution strategy for the cell-centered finite volume method. To obtain high-order accuracy for both solution and gradient variables, we use a successive order solution reconstruction: constant, linear, and quadratic (k-exact) reconstruction with an efficient reconstruction stencil, a so-called wrapping stencil. By the virtue of the cell-centered scheme, the source term evaluation was greatly simplified regardless of the solution order. For uniform schemes, we obtain the same order of accuracy, i.e., first, second, and third orders, for both the solution and its gradient variables. For hybrid schemes, recycling the gradient variable information for solution variable reconstruction makes one order of additional accuracy, i.e., second, third, and fourth orders, possible for the solution variable with less computational work than needed for uniform schemes. In general, the hyperbolic method can be an effective solution technique for diffusion problems, but instability is also observed for the discontinuous diffusion coefficient cases, which brings necessity for further investigation about the monotonicity preserving hyperbolic diffusion method.

  7. High order Fuchsian equations for the square lattice Ising model: {chi}-tilde{sup (5)}

    Energy Technology Data Exchange (ETDEWEB)

    Bostan, A [INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105 78153 Le Chesnay, Cedex (France); Boukraa, S [LPTHIRM and Departement d' Aeronautique, Universite de Blida (Algeria); Guttmann, A J; Jensen, I [ARC Centre of Excellence for Mathematics and Statistics of Complex Systems, Department of Mathematics and Statistics, University of Melbourne, Victoria 3010 (Australia); Hassani, S; Zenine, N [Centre de Recherche Nucleaire d' Alger, 2 Bd. Frantz Fanon, BP 399, 16000 Alger (Algeria); Maillard, J-M [LPTMC, UMR 7600 CNRS, Universite de Paris, Tour 24, 4eme etage, case 121, 4 Place Jussieu, 75252 Paris Cedex 05 (France)], E-mail: alin.bostan@inria.fr, E-mail: boukraa@mail.univ-blida.dz, E-mail: tonyg@ms.unimelb.edu.au, E-mail: I.Jensen@ms.unimelb.edu.au, E-mail: maillard@lptmc.jussieu.fr, E-mail: maillard@lptl.jussieu.fr, E-mail: njzenine@yahoo.com

    2009-07-10

    We consider the Fuchsian linear differential equation obtained (modulo a prime) for {chi}-tilde{sup (5)}, the five-particle contribution to the susceptibility of the square lattice Ising model. We show that one can understand the factorization of the corresponding linear differential operator from calculations using just a single prime. A particular linear combination of {chi}-tilde{sup (1)} and {chi}-tilde{sup (3)} can be removed from {chi}-tilde{sup (5)} and the resulting series is annihilated by a high order globally nilpotent linear ODE. The corresponding (minimal order) linear differential operator, of order 29, splits into factors of small orders. A fifth-order linear differential operator occurs as the left-most factor of the 'depleted' differential operator and it is shown to be equivalent to the symmetric fourth power of L{sub E}, the linear differential operator corresponding to the elliptic integral E. This result generalizes what we have found for the lower order terms {chi}-tilde{sup (3)} and {chi}-tilde{sup (4)}. We conjecture that a linear differential operator equivalent to a symmetric (n - 1) th power of L{sub E} occurs as a left-most factor in the minimal order linear differential operators for all {chi}-tilde{sup (n)}'s.

  8. Unconventional charge order in a co-doped high-Tc superconductor

    Science.gov (United States)

    Pelc, D.; Vučković, M.; Grafe, H.-J.; Baek, S.-H.; Požek, M.

    2016-09-01

    Charge-stripe order has recently been established as an important aspect of cuprate high-Tc superconductors. However, owing to the complex interplay between competing phases and the influence of disorder, it is unclear how it emerges from the parent high-temperature state. Here we report on the discovery of an unconventional ordered phase between charge-stripe order and (pseudogapped) metal in the cuprate La1.8-xEu0.2SrxCuO4. We use three complementary experiments--nuclear quadrupole resonance, nonlinear conductivity and specific heat--to demonstrate that the order appears through a sharp phase transition and exists in a dome-shaped region of the phase diagram. Our results imply that the new phase is a state, which preserves translational symmetry: a charge nematic. We thus resolve the process of charge-stripe development in cuprates, show that this nematic phase is distinct from high-temperature pseudogap and establish a link with other strongly correlated electronic materials with prominent nematic order.

  9. Unconventional charge order in a co-doped high-Tc superconductor.

    Science.gov (United States)

    Pelc, D; Vučković, M; Grafe, H-J; Baek, S-H; Požek, M

    2016-09-08

    Charge-stripe order has recently been established as an important aspect of cuprate high-Tc superconductors. However, owing to the complex interplay between competing phases and the influence of disorder, it is unclear how it emerges from the parent high-temperature state. Here we report on the discovery of an unconventional ordered phase between charge-stripe order and (pseudogapped) metal in the cuprate La1.8-xEu0.2SrxCuO4. We use three complementary experiments-nuclear quadrupole resonance, nonlinear conductivity and specific heat-to demonstrate that the order appears through a sharp phase transition and exists in a dome-shaped region of the phase diagram. Our results imply that the new phase is a state, which preserves translational symmetry: a charge nematic. We thus resolve the process of charge-stripe development in cuprates, show that this nematic phase is distinct from high-temperature pseudogap and establish a link with other strongly correlated electronic materials with prominent nematic order.

  10. Highly Crystalline Mesoporous C60 with Ordered Pores: A Class of Nanomaterials for Energy Applications.

    Science.gov (United States)

    Benzigar, Mercy R; Joseph, Stalin; Ilbeygi, Hamid; Park, Dae-Hwan; Sarkar, Sujoy; Chandra, Goutam; Umapathy, Siva; Srinivasan, Sampath; Talapaneni, Siddulu Naidu; Vinu, Ajayan

    2017-11-08

    Highly ordered mesoporous C60 with a well-ordered porous structure and a high crystallinity is prepared through the nanohard templating method using a saturated solution of C60 in 1-chloronaphthalene (51 mg mL-1 ) as a C60 precursor and SBA-15 as a hard template. The high solubility of C60 in 1-chloronaphthalene helps not only to encapsulate a huge amount of the C60 into the mesopores of the template but also supports the oligomerization of C60 and the formation of crystalline walls made of C60 . The obtained mesoporous C60 exhibits a rod-shaped morphology, a high specific surface area (680 m2  g-1 ), tuneable pores, and a highly crystalline wall structure. This exciting ordered mesoporous C60 offers high supercapacitive performance and a high selectivity to H2 O2 production and methanol tolerance for ORR. This simple strategy could be adopted to make a series of mesoporous fullerenes with different structures and carbon atoms as a new class of energy materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Thermodynamics phase changes of nanopore fluids

    KAUST Repository

    Islam, Akand W.

    2015-07-01

    The van der Waals (vdW) equation (Eq.) is modified to describe thermodynamic of phase behavior of fluids confined in nanopore. Our aim is to compute pressures exerted by the fluid molecules and to investigate how they change due to pore proximity by assuming the pore wall is inert. No additional scaling of model parameters is imposed and original volume and energy parameters are used in the calculations. Our results clearly show the phase changes due to confinement. The critical shifts of temperatures and pressures are in good agreement compared to the laboratory data and molecular simulation. Peng-Robinson (PR) equation-of-state (EOS) has resulted in different effect than the vdW. This work delivers insights into the nature of fluid behavior in extremely low-permeability nanoporous media, especially in the tight shale reservoirs, below the critical temperatures. © 2015 Elsevier B.V.

  12. Gyroid Membranes made from Nanoporous Blck Copolymers

    DEFF Research Database (Denmark)

    Szewczykowski, Piotr Plzemystaw; Vigild, Martin Etchells; Ndoni, Sokol

    2007-01-01

    Nanoporous materials are interesting and exciting materials in view of their many potential applications, especially as ultrafiltration membranes. One way of preparing nanoporous polymeric materials is to use block copolymers. Block copolymers have the great advantage that they organize them......-selves into different morphologies on the nano scale. Block copolymer synthesis controls the molecular weight and volume fraction of blocks, which determine the resulting nano-structures. From a membrane application point of view one very suitable morphology is the bicontinuous gyroid. Mechanical stability...... of the membrane and its nanoporosity is e.g. obtained by cross-linking the majority blocks and selectively etching the minority blocks. Here we report on ultrafiltration membranes prepared from a 1,2-polybutadiene-b-polydimethylsiloxane diblock copolymer with gyroid structure. Different experimental methods...

  13. Wool Carpet Dye Adsorption on Nanoporous Carbon Materials Derived from Agro-Product

    Directory of Open Access Journals (Sweden)

    Raja Ram Pradhananga

    2017-04-01

    Full Text Available In this paper, wool carpet dye adsorption properties of nanoporous activated carbon materials (NCMs prepared from bamboo agro-product is reported. Bamboo cane powder was chemically activated with phosphoric acid at different temperatures (400, 500, and 600 °C at an impregnation ratio of 1:1. We found that the specific surface area and the total pore volume of NCM increases with temperature giving the highest surface area and pore volume ca. 2130 m2·g−1 and 2.69 cc·g−1 at 600 °C. Owing to superior surface textural properties, bamboo-derived NCM showed excellent adsorption capacity for wool carpet dyes Lanasyn orange (LO and Lanasyn gray (LG. The adsorption phenomena could be described by Langmuir/Freundlich adsorption isotherm models. The maximum adsorption capacity was ca. 2.60 × 103 and 3.04 × 103 mg·g−1 for LO and LG, respectively. The adsorption followed pseudo second order kinetics with the second order rate constant of 1.24 × 10−3 g·mg−1·min−1 (LO and 7.69 × 10−4 g·mg−1·min−1 (LG, respectively. This study demonstrated that the high surface area NCMs prepared from agro-product can be used as efficient and cost-effective adsorbent materials for the removal of dyes from industrial effluent.

  14. Prediction model of sinoatrial node field potential using high order partial least squares.

    Science.gov (United States)

    Feng, Yu; Cao, Hui; Zhang, Yanbin

    2015-01-01

    High order partial least squares (HOPLS) is a novel data processing method. It is highly suitable for building prediction model which has tensor input and output. The objective of this study is to build a prediction model of the relationship between sinoatrial node field potential and high glucose using HOPLS. The three sub-signals of the sinoatrial node field potential made up the model's input. The concentration and the actuation duration of high glucose made up the model's output. The results showed that on the premise of predicting two dimensional variables, HOPLS had the same predictive ability and a lower dispersion degree compared with partial least squares (PLS).

  15. Quantum Key Distribution with High Order Fibonacci-like Orbital Angular Momentum States

    Science.gov (United States)

    Pan, Ziwen; Cai, Jiarui; Wang, Chuan

    2017-08-01

    The coding space in quantum communication could be expanded to high-dimensional space by using orbital angular momentum (OAM) states of photons, as both the capacity of the channel and security are enhanced. Here we present a novel approach to realize high-capacity quantum key distribution (QKD) by exploiting OAM states. The innovation of the proposed approach relies on a unique type of entangled-photon source which produces entangled photons with OAM randomly distributed among high order Fiboncci-like numbers and a new physical mechanism for efficiently sharing keys. This combination of entanglement with mathematical properties of high order Fibonacci sequences provides the QKD protocol immunity to photon-number-splitting attacks and allows secure generation of long keys from few photons. Unlike other protocols, reference frame alignment and active modulation of production and detection bases are unnecessary.

  16. Construction of Low Dissipative High Order Well-Balanced Filter Schemes for Non-Equilibrium Flows

    Science.gov (United States)

    Wang, Wei; Yee, H. C.; Sjogreen, Bjorn; Magin, Thierry; Shu, Chi-Wang

    2009-01-01

    The goal of this paper is to generalize the well-balanced approach for non-equilibrium flow studied by Wang et al. [26] to a class of low dissipative high order shock-capturing filter schemes and to explore more advantages of well-balanced schemes in reacting flows. The class of filter schemes developed by Yee et al. [30], Sjoegreen & Yee [24] and Yee & Sjoegreen [35] consist of two steps, a full time step of spatially high order non-dissipative base scheme and an adaptive nonlinear filter containing shock-capturing dissipation. A good property of the filter scheme is that the base scheme and the filter are stand alone modules in designing. Therefore, the idea of designing a well-balanced filter scheme is straightforward, i.e., choosing a well-balanced base scheme with a well-balanced filter (both with high order). A typical class of these schemes shown in this paper is the high order central difference schemes/predictor-corrector (PC) schemes with a high order well-balanced WENO filter. The new filter scheme with the well-balanced property will gather the features of both filter methods and well-balanced properties: it can preserve certain steady state solutions exactly; it is able to capture small perturbations, e.g., turbulence fluctuations; it adaptively controls numerical dissipation. Thus it shows high accuracy, efficiency and stability in shock/turbulence interactions. Numerical examples containing 1D and 2D smooth problems, 1D stationary contact discontinuity problem and 1D turbulence/shock interactions are included to verify the improved accuracy, in addition to the well-balanced behavior.

  17. Nanoporous polymer ring resonators for biosensing

    OpenAIRE

    Mancuso, Matthew; Goddard, Julie M.; Erickson, David

    2011-01-01

    Optically resonant devices are promising as label-free biomolecular sensors due to their ability to concentrate electromagnetic energy into small mode volumes and their capacity for multiplexed detection. A fundamental limitation of current optical biosensor technology is that the biomolecular interactions are limited to the surface of the resonant device, while the highest intensity of electromagnetic energy is trapped within the core. In this paper, we present nanoporous polymer optofluidic...

  18. Nanoporous Silicon Ignition of JA2 Propellant

    Science.gov (United States)

    2014-06-01

    suggested the use of an additional igniter material. Nano bismuth oxide and nano cuprous oxide thermites were both attempted as supplemental igniter...materials. The nano bismuth oxide thermite did not ignite the JA2, but the nano cuprous thermite did succussfully provide ignition. 15. SUBJECT TERMS...nanoporous silicon, JA2 propellant, thermite , ignition 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 26

  19. Electroosmotic flow rectification in conical nanopores

    OpenAIRE

    Laohakunakorn, Nadanai; Keyser, Ulrich F.

    2015-01-01

    Recent experimental work has suggested that electroosmotic flows (EOF) through conical nanopores exhibit rectification in the opposite sense to the well-studied effect of ionic current rectification. A positive bias voltage generates large EOF and small current, while negative voltages generate small EOF and large current. Here we systematically investigate this effect using finite-element simulations. We find that inside the pore, the electric field and salt concentration are inversely corre...

  20. 10th International Conference on Spectral and High-Order Methods

    CERN Document Server

    Berzins, Martin; Hesthaven, Jan

    2015-01-01

    The book contains a selection of high quality papers, chosen among the best presentations during the International Conference on Spectral and High-Order Methods (2014), and provides an overview of the depth and breadth of the activities within this important research area.  The carefully reviewed selection of papers will provide the reader with a snapshot of the state-of-the-art and help initiate new research directions through the extensive biography.