WorldWideScience

Sample records for nanoporous materials banff

  1. 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...

  2. Hydrophilic nanoporous materials

    DEFF Research Database (Denmark)

    2010-01-01

    .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...

  3. 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.

  4. Banff Challenge 2

    CERN Document Server

    Junk, Thomas R

    2011-01-01

    Experimental particle physics collaborations constantly seek newer and better ideas for improving the sensitivity of their searches for new particles and phenomena. Statistical techniques are the last step in interpreting the results of an experiment; they are used to make discoveries (hypothesis testing), and to measure parameters (point estimation). They are also used in the first step - experiment and analysis design. Banff Challenge 2 asks participants to test their methods of disco vering hidden signals in simulated datasets and of measuring the properties of these signals. The Challenge problems are described, and the performances of the submitted entries is summarized, for datasets with and without simulated signals present.

  5. Nanoporous materials for energy applications

    Science.gov (United States)

    Yonemoto, Bryan T.

    Batteries have become ubiquitous in modern society by powering small, consumer electronic devices such as flashlights, cell phones, and laptops. Increasingly, batteries are also being examined as a method to improve energy efficiency (and reduce greenhouse gas emissions) for vehicles and power transmission/distribution applications. For lithium-ion based batteries to meet the demands of these new applications, new electrode materials and morphologies are the key to access high energy and/or power density. In this work, the research efforts include two major thrusts, concentrating on the synthesis and understanding of novel porous materials as potential electrodes for rechargeable lithium-ion batteries. The nano-sized walls and multidimensional pore structures allow fast solid state and electrolytic transport, while micron-sized particle ensure better interparticulate contact. The first thrust of research focused on the development of new synthetic approaches for porous material fabrication. A novel ionothermal synthetic method has been developed using deep-eutectic solvents, such as choline chloride and N,N-dimethylurea, to form iron, manganese and cobalt phosphates with a zeotype framework. Through this advanced method the successful synthesis of 4 previously undiscovered metal phosphate zeotypes was achieved. A careful control of water content during the ionothermal synthesis elucidated the multistep decomposition of our framework template and its impacts in the resulting zeotype structures. Upon conclusion of the ionothermal work, the focus shifted to the methodology development for mesoporous metal sulfides. An "oxide-to-sulfide" synthetic strategy was developed for the first time, resulting in the first synthesis of ordered porous iron, cobalt and nickel sulfides. More importantly, this is a general synthetic method, relying primarily on volumetric calculations per metal atom, which could be further extend to other metal-containing compounds, such as metal

  6. Nanoporous Silicon Based Energetic Materials

    Science.gov (United States)

    2008-12-01

    performed at SINTEF , Norway as shown in Figure 4 (line a). 3 Annealing PSi in air at different temperatures can be used to change the surface...3h (c)PSi annealed at 500C for 0.5 h (courtesy SINTEF ) e is C d magnification bright field TEM image of PSi-Fe2O3. The inset electron...Dr. Knut Thorshaug and Dr Diplos Spyros of SINTEF Norway for DRIFTS and XPS data. REFERENCES dvanced Energetics Materials, 2004; report byA ring

  7. Surface effects on the mechanical properties of nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Xia Re [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Li Xide; Feng Xiqiao [AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Qin Qinghua [School of Engineering, Australian National University, Canberra, ACT 0200 (Australia); Liu Jianlin, E-mail: fengxq@tsinghua.edu.cn [Department of Engineering Mechanics, China University of Petroleum, Qingdao 266555 (China)

    2011-07-01

    Using the theory of surface elasticity, we investigate the mechanical properties of nanoporous materials. The classical theory of porous materials is modified to account for surface effects, which become increasingly important as the characteristic sizes of microstructures shrink to nanometers. First, a refined Timoshenko beam model is presented to predict the effective elastic modulus of nanoporous materials. Then the surface effects on the elastic microstructural buckling behavior of nanoporous materials are examined. In particular, nanoporous gold is taken as an example to illustrate the application of the proposed model. The results reveal that both the elastic modulus and the critical buckling behavior of nanoporous materials exhibit a distinct dependence on the characteristic sizes of microstructures, e.g. the average ligament width.

  8. 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.

  9. Electroanalysis using modified hierarchical nanoporous carbon materials.

    Science.gov (United States)

    Rodriguez, Rusbel Coneo; Moncada, Angelica Baena; Acevedo, Diego F; Planes, Gabriel A; Miras, Maria C; Barbero, Cesar A

    2013-01-01

    The role of the electrode nanoporosity in electroanalytical processes is discussed and specific phenomena (slow double layer charging, local pH effects) which can be present in porous electrode are described. Hierarchical porous carbon (HPC) materials are synthesized using a hard template method. The three dimensional carbon porosity is examined using scanning electron microscopy on flat surfaces cut using a focused ion beam (FIB-SEM). The electrochemical properties of the HPC are measured using cyclic voltammetry, AC impedance, chronoamperometry and Probe Beam Deflection (PBD) techniques. Chronoamperometry measurements of HPC seems to fit a transmission line model. PBD data show evidence of local pH changes inside the pores, during double layer charging. The HPC are modified by in situ (chemical or electrochemical) formation of metal (Pt/Ru) or metal oxide (CoOx, Fe3O4) nanoparticles. Additionally, HPC loaded with Pt decorated magnetite (Fe3O4) nanoparticles is produced by galvanic displacement. The modified HPC materials are used for the electroanalysis of different substances (CO, O2, AsO3(-3)). The role of the nanoporous carbon substrate in the electroanalytical data is evaluated.

  10. Deformation mechanism of nanoporous materials upon water freezing and melting

    Science.gov (United States)

    Erko, Maxim; Wallacher, Dirk; Paris, Oskar

    2012-10-01

    Temperature-induced non-monotonous reversible deformation of water-filled nanoporous silica materials is investigated experimentally using in-situ small-angle x-ray scattering. The influence of freezing and melting in the nanopores on this deformation is treated quantitatively by introducing a simple model based on the Gibbs-Thomson equation and a generalized Laplace-pressure. The physical origin of the melting/freezing induced pore lattice deformation is found to be exactly the same as for capillary condensation/evaporation, namely the curved phase boundary due to the preferred wetting of the pore walls by the liquid phase. As a practical implication, elastic properties of the nanoporous framework can be determined from the temperature-deformation curves.

  11. From Block Copolymers to Nano-porous Materials

    DEFF Research Database (Denmark)

    Vigild, Martin Etchells; Ndoni, Sokol; Berg, Rolf Henrik

    2003-01-01

    Quantitative etching of the polydimethylsiloxane block in a series of polystyrene-polydimethylsiloxane (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride (HF) renders a nanoporous material with the remaining PS maintaining the original morphology...

  12. Solid-State Explosive Reaction for Nanoporous Bulk Thermoelectric Materials.

    Science.gov (United States)

    Zhao, Kunpeng; Duan, Haozhi; Raghavendra, Nunna; Qiu, Pengfei; Zeng, Yi; Zhang, Wenqing; Yang, Jihui; Shi, Xun; Chen, Lidong

    2017-09-29

    High-performance thermoelectric materials require ultralow lattice thermal conductivity typically through either shortening the phonon mean free path or reducing the specific heat. Beyond these two approaches, a new unique, simple, yet ultrafast solid-state explosive reaction is proposed to fabricate nanoporous bulk thermoelectric materials with well-controlled pore sizes and distributions to suppress thermal conductivity. By investigating a wide variety of functional materials, general criteria for solid-state explosive reactions are built upon both thermodynamics and kinetics, and then successfully used to tailor material's microstructures and porosity. A drastic decrease in lattice thermal conductivity down below the minimum value of the fully densified materials and enhancement in thermoelectric figure of merit are achieved in porous bulk materials. This work demonstrates that controlling materials' porosity is a very effective strategy and is easy to be combined with other approaches for optimizing thermoelectric performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Computational development of the nanoporous materials genome

    Science.gov (United States)

    Boyd, Peter G.; Lee, Yongjin; Smit, Berend

    2017-08-01

    There is currently a push towards big data and data mining in materials research to accelerate discovery. Zeolites, metal-organic frameworks and other related crystalline porous materials are not immune to this phenomenon, as evidenced by the proliferation of porous structure databases and computational gas-adsorption screening studies over the past decade. The endeavour to identify the best materials for various gas separation and storage applications has led not only to thousands of synthesized structures, but also to the development of algorithms for building hypothetical materials. The materials databases assembled with these algorithms contain a much wider range of complex pore structures than have been synthesized, with the reasoning being that we have discovered only a small fraction of realizable structures and expanding upon these will accelerate rational design. In this Review, we highlight the methods developed to build these databases, and some of the important outcomes from large-scale computational screening studies.

  14. 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.

  15. 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.

  16. Nanoporous materials for reducing the over potential of creating hydrogen by water electrolysis

    Science.gov (United States)

    Anderson, Marc A.; Leonard, Kevin C.

    2016-06-14

    Disclosed is an electrolyzer including an electrode including a nanoporous oxide-coated conducting material. Also disclosed is a method of producing a gas through electrolysis by contacting an aqueous solution with an electrode connected to an electrical power source, wherein the electrode includes a nanoporous oxide-coated conducting material.

  17. Capture of formaldehyde by adsorption on nanoporous materials.

    Science.gov (United States)

    Bellat, Jean-Pierre; Bezverkhyy, Igor; Weber, Guy; Royer, Sébastien; Averlant, Remy; Giraudon, Jean-Marc; Lamonier, Jean-François

    2015-12-30

    The aim of this work is to assess the capability of a series of nanoporous materials to capture gaseous formaldehyde by adsorption in order to develop air treatment process and gas detection in workspaces or housings. Adsorption-desorption isotherms have been accurately measured at room temperature by TGA under very low pressure (pmesoporous silica (SBA15), activated carbon (AC NORIT RB3) and metal organic framework (MOF, Ga-MIL-53), exhibiting a wide range of pore sizes and surface properties. Results reveal that the NaX, NaY and CuX faujasite (FAU) zeolites are materials which show strong adsorption capacity and high affinity toward formaldehyde. In addition, these materials can be completely regenerated by heating at 200°C under vacuum. These cationic zeolites are therefore promising candidates as adsorbents for the design of air depollution process or gas sensing applications.

  18. Nanoporous metal organic framework materials for hydrogen storage

    Institute of Scientific and Technical Information of China (English)

    Bo Xiao; Qingchun Yuan

    2009-01-01

    Hydrogen is expected to play an important role in future transportation as a promising alternative clean energy source to carbon-based fuels.One of the key challenges to commercialize hydrogen energy is to develop appropriate onboard hydrogen storage systems,capable of charging and discharging large quantities of hydrogen with fast enough kinetics to meet commercial requirements.Metal organic framework (MOF) is a new type of inorganic and organic hybrid nanoporous particulate materials.Its diverse networks can enhance hydrogen storage through tuning the structure and property of MOFs.The MOF materials so far developed adsorb hydrogen through weak disperston interactions,which allow significant quantity of hydrogen to be stored at cryogenic temperatures with fast kinetics.Novel MOFs are being developed to strengthen the interactions between hydrogen and MOFs in order to store hydrogen under ambient conditions.This review surveys the development of such candidate materials,their performance and future research needs.

  19. Saturation properties of a supercritical gas sorbed in nanoporous materials.

    Science.gov (United States)

    Poirier, Eric; Dailly, Anne

    2012-12-28

    The description of experimental gas adsorption data in terms of an accurate model is key to understand the adsorption mechanism and its limits. As a basic feature such a model should predict correctly the conditions under which saturation occurs. However, in the absence of bulk condensation properties for a supercritical adsorbate this matter remains open to discussions. In this study, the decreasing region of excess hydrogen adsorption isotherms measured down to 50 K is used to determine the adsorbed phase volume, density and pressure corresponding to saturation. The experimental method developed for these key measurements addresses the challenges of very low temperature adsorption measurements at high pressure. Therefore, the modifications specially made to a cryostat used in conjunction with a Sievert apparatus to reach high temperature stability (±10 mK) down to 40 K are presented. The approach is implemented on the novel nanoporous materials UMCM-1 and NOTT-112 over 50-77 K and 0-40 bar. The derived hydrogen saturation properties are found to be consistent with a Dubinin-Astakhov model. Importantly, the measured adsorbed hydrogen phase volume also compares well with the pore volume obtained from Ar porosimetry. The found saturation properties provide a physical basis to calculate consistent absolute adsorption isotherms and enthalpies, and to project the ultimate adsorption capacity of a conceptual material with a maximized specific surface area. The present findings provide additional evidence that the common view on supercritical adsorption, in which it is assumed that no liquid is formed and that the only possible mechanism involves monolayer coverage, does not hold in many nanoporous materials.

  20. Advanced structural analysis of nanoporous materials by thermal response measurements.

    Science.gov (United States)

    Oschatz, Martin; Leistner, Matthias; Nickel, Winfried; Kaskel, Stefan

    2015-04-07

    Thermal response measurements based on optical adsorption calorimetry are presented as a versatile tool for the time-saving and profound characterization of the pore structure of porous carbon-based materials. This technique measures the time-resolved temperature change of an adsorbent during adsorption of a test gas. Six carbide and carbon materials with well-defined nanopore architecture including micro- and/or mesopores are characterized by thermal response measurements based on n-butane and carbon dioxide as the test gases. With this tool, the pore systems of the model materials can be clearly distinguished and accurately analyzed. The obtained calorimetric data are correlated with the adsorption/desorption isotherms of the materials. The pore structures can be estimated from a single experiment due to different adsorption enthalpies/temperature increases in micro- and mesopores. Adsorption/desorption cycling of n-butane at 298 K/1 bar with increasing desorption time allows to determine the pore structure of the materials in more detail due to different equilibration times. Adsorption of the organic test gas at selected relative pressures reveals specific contributions of particular pore systems to the increase of the temperature of the samples and different adsorption mechanisms. The use of carbon dioxide as the test gas at 298 K/1 bar provides detailed insights into the ultramicropore structure of the materials because under these conditions the adsorption of this test gas is very sensitive to the presence of pores smaller than 0.7 nm.

  1. The Effect of Pore Size of Nanoporous Material for Lithium Ion Batteries

    Institute of Scientific and Technical Information of China (English)

    L.J.Fu; G.J.Wang; Y.P.Wu

    2007-01-01

    1 Results 3-dimensionally ordered mesoporous materials have been used as electrode materials for lithium ion batteries to improve their electrochemical performance by decreasing the polarization during cycling.Our synthesize nanoporous TiO2 particles without substrate present enhanced cycle performance compared with that of previous reports[1]. Here we report our results referring to that nanoporous TiO2 materials with different pore sizes exhibit different electrochemical performance.The detail procedu...

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

    NARCIS (Netherlands)

    R. Krishna; J.M. van Baten

    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 f

  3. Davisson-Germer Prize Talk: Hydrogen storage in nanoporous materials

    Science.gov (United States)

    Chabal, Yves

    2009-03-01

    To develop a hydrogen-based energy technology, several classes of materials are being considered to achieve the DOE targets for gravimetric and volumetric hydrogen densities for hydrogen storage, including liquids (e.g. ammonium borohydrides), clathrate structures, complex metal hydrides, nanostructured (e.g. carbon) an nanoporous materials. Fundamental studies are necessary to determine the ultimate hydrogen capacity of each system. Nanoporous Metal-organic Framework (MOF) materials are promising candidates for hydrogen storage because the chemical nature and size of their unit cell can be tailored to weakly attract and incorporate H2 molecules, with good volumetric and mass density. In this talk, we consider the structure M2(BDC)2(TED), where M is a metal atom (Zn, Ni, Cu), BDC is benzenedicarboxylate and TED triethylenediamine, to determine the location and interaction of H2 molecules within the MOF. These compounds are isostructural and crystallize in the tetragonal phase (space group P4/ncc), they construct 3D porous structures with relatively large pore size (˜7-8 A ), pore volume (˜0.63-0.84 cc/g) and BET surface area (˜1500-1900 m^2/g). At high pressures (300-800 psi), the perturbation of the H-H stretching mode can be measured with IR absorption spectroscopy, showing a 35 cm-1 redshift from the unperturbed ortho (4155 cm-1 ) and para (4161 cm-1 ) frequencies. Using a newly developed non empirical van der Waals DFT method vdW-DFT),ootnotetextJ.Y. Lee, D.H. Olson, L. Pan, T.J. Emge, J. Li, Adv. Func. Mater. 17, 1255 (2007) it can be shown that the locus of the deepest H2 binding positions lies within to types of narrow channels. The energies of the most stable binding sites, as well as the number of such binding sites, are consistent with the values obtained from experimental adsorption isotherms, and heat of adsorption) data.ootnotetextM. Dion, H. Ryberg, E. Schroder, D. C. Langreth, B.I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004). Importantly, the

  4. Polyhedral Boranes: A Versatile Building Block for Nanoporous Materials

    Science.gov (United States)

    Clingerman, Daniel Jon

    The studies described in this dissertation examine several new concepts related to polyhedral boranes and their applications towards the synthesis of novel nanoporous materials. The unique thermal and chemical robustness, rigidity, quasi-spherical geometry, and high boron content of polyhedral boranes are explored to generate materials not possible with typical organic synthons. Aside from the fundamental synthetic work, this work was also aimed at solving larger global issues such as energy storage and new routes to therapeutics. Chapter 2 highlights the discovery of the first highly porous carborane-based metal-organic framework, where the spherical nature of the carborane increases volumetric surface area without reducing pore volume. Chapter 3 examines the first tritopic carborane-based ligand and the stabilizing effect the rigid, sterically bulky carboranyl groups have on highly porous topologies not stable with typical organic ligands. Chapters 4 and 5 describe the use of polyhedral borane-based ligands as a means to influence and generate unexpected topologies. Lastly, chapter 6 explores using a simple carborane-based ligand that harnesses the power of coordination-driven assembly to rapidly generate a high boron-containing supramolecular cuboctahedron.

  5. Nanoporous Carbide-Derived Carbon Material-Based Linear Actuators

    Directory of Open Access Journals (Sweden)

    Janno Torop

    2009-12-01

    Full Text Available Devices using electroactive polymer-supported carbon material can be exploited as alternatives to conventional electromechanical actuators in applications where electromechanical actuators have some serious deficiencies. One of the numerous examples is precise microactuators. In this paper, we show for first time the dilatometric effect in nanocomposite material actuators containing carbide-derived carbon (CDC and polytetrafluoroetylene polymer (PTFE. Transducers based on high surface area carbide-derived carbon electrode materials are suitable for short range displacement applications, because of the proportional actuation response to the charge inserted, and high Coulombic efficiency due to the EDL capacitance. The material is capable of developing stresses in the range of tens of N cm-2. The area of an actuator can be dozens of cm2, which means that forces above 100 N are achievable. The actuation mechanism is based on the interactions between the high-surface carbon and the ions of the electrolyte. Electrochemical evaluations of the four different actuators with linear (longitudinal action response are described. The actuator electrodes were made from two types of nanoporous TiC-derived carbons with surface area (SA of 1150 m2 g-1 and 1470 m2 g-1, respectively. Two kinds of electrolytes were used in actuators: 1.0 M tetraethylammonium tetrafluoroborate (TEABF4 solution in propylene carbonate and pure ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf. It was found that CDC based actuators exhibit a linear movement of about 1% in the voltage range of 0.8 V to 3.0 V at DC. The actuators with EMITf electrolyte had about 70% larger movement compared to the specimen with TEABF4 electrolyte.

  6. Optical Sensors for Biomolecules Using Nanoporous Sol-Gel Materials

    Science.gov (United States)

    Fang, Jonathan; Zhou, Jing C.; Lan, Esther H.; Dunn, Bruce; Gillman, Patricia L.; Smith, Scott M.

    2004-01-01

    An important consideration for space missions to Mars is the ability to detect biosignatures. Solid-state sensing elements for optical detection of biological entities are possible using sol-gel based biologically active materials. We have used these materials as optical sensing elements in a variety of bioassays, including immunoassays and enzyme assays. By immobilizing an appropriate biomolecule in the sol-gel sensing element, we have successfully detected analytes such as amino acids and hormones. In the case of the amino acid glutamate, the enzyme glutamate dehydrogenase was the immobilized molecule, whereas in the case of the hormone cortisol, an anti-cortisol antibody was immobilized in the sensing element. In this previous work with immobilized enzymes and antibodies, excellent sensitivity and specificity were demonstrated in a variety of formats including bulk materials, thin films and fibers. We believe that the sol-gel approach is an attractive platform for bioastronautics sensing applications because of the ability to detect a wide range of entities such as amino acids, fatty acids, hopanes, porphyrins, etc. The sol-gel approach produces an optically transparent 3D silica matrix that forms around the biomolecule of interest, thus stabilizing its structure and functionality while allowing for optical detection. This encapsulation process protects the biomolecule and leads to a more "rugged" sensor. The nanoporous structure of the sol-gel matrix allows diffusion of small target molecules but keeps larger, biomolecules immobilized in the pores. We are currently developing these biologically active sol-gel materials into small portable devices for on-orbit cortisol detection

  7. Methane storage in nanoporous material at supercritical temperature over a wide range of pressures

    OpenAIRE

    Keliu Wu; Zhangxin Chen; Xiangfang Li; Xiaohu Dong

    2016-01-01

    The methane storage behavior in nanoporous material is significantly different from that of a bulk phase, and has a fundamental role in methane extraction from shale and its storage for vehicular applications. Here we show that the behavior and mechanisms of the methane storage are mainly dominated by the ratio of the interaction between methane molecules and nanopores walls to the methane intermolecular interaction, and a geometric constraint. By linking the macroscopic properties of the met...

  8. Surface Diffusion Effect on Gas Transport in Nanoporous Materials

    Science.gov (United States)

    Hori, Takuma; Yoshimoto, Yuta; Takagi, Shu; Kinefuchi, Ikuya

    2016-11-01

    Polymer electrolyte fuel cells are one of the promising candidates for power sources of electric vehicles. For further improvement of their efficiency in high current density operation, a better understanding of oxygen flow inside the cells, which have micro- or nanoporous structures, is necessary. Molecular simulations such as the direct simulation of Monte Carlo (DSMC) are necessary to elucidate flow phenomena in micro- or nanostructures since the Knudsen number is close to unity. Our previous report showed that the oxygen diffusion resistance in porous structures with a characteristic pore size of 100 nm calculated by DSMC agrees well with that measured experimentally. On the other hand, when it comes to the transport in structures with much smaller pore sizes, it is expected that the surface diffusion has a significant impact on gas transport because of their higher specific surface area. Here we present the calculation of gas transport in porous structures with considering surface diffusion. The numerical porous structure models utilized in our simulations are constructed from three-dimensional imaging of materials. The effect of the distance of random walk on the total diffusion resistance in the structures is discussed. This paper is based on results obtained from a project commissioned by the New Energy and Industrial Development Organization (NEDO).

  9. Advanced Nanoporous Materials for Micro-Gravimetric Sensing to Trace-Level Bio/Chemical Molecules

    Directory of Open Access Journals (Sweden)

    Pengcheng Xu

    2014-10-01

    Full Text Available 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.

  10. 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.

  11. Synthesis of Foam-Shaped Nanoporous Zeolite Material: A Simple Template-Based Method

    Science.gov (United States)

    Saini, Vipin K.; Pires, Joao

    2012-01-01

    Nanoporous zeolite foam is an interesting crystalline material with an open-cell microcellular structure, similar to polyurethane foam (PUF). The aluminosilicate structure of this material has a large surface area, extended porosity, and mechanical strength. Owing to these properties, this material is suitable for industrial applications such as…

  12. Slow dynamics of supercooled water confined in nanoporous silica materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L [Department of Nuclear Engineering, 24-209 MIT, Cambridge, MA 02139 (United States); Faraone, A [Department of Nuclear Engineering, 24-209 MIT, Cambridge, MA 02139 (United States); Mou, C-Y [Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan (China); Yen, C-W [Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan (China); Chen, S-H [Department of Nuclear Engineering, 24-209 MIT, Cambridge, MA 02139 (United States)

    2004-11-17

    We review our incoherent quasielastic neutron scattering (QENS) studies of the dynamics of supercooled water confined in nanoporous silica materials. QENS data were analysed by using the relaxing cage model (RCM) previously developed by us. We first use molecular dynamics (MD) simulation of the extended simple point charge model (SPC/E) for bulk supercooled water to establish the validity of the RCM, which applies to both the translational and rotational motion of water molecules. We then assume that the dynamics of water molecules in the vicinity of a hydrophilic surface is similar to a bulk water at an equivalent lower supercooled temperature. This analogy was experimentally demonstrated in previous investigations of water in Vycor glasses and near hydrophilic protein surfaces. Studies were made of supercooled water in MCM-41-S (pore sizes 25, 18, and 14 A) and MCM-48-S (pore size 22 A) using three QENS spectrometers of respective energy resolutions 1, 30, and 60 {mu}eV, covering the temperature range from 325 to 200 K. Five quantities are extracted from the analysis: they are {beta}, the stretch exponent characterizing the {alpha}-relaxation; {beta}{gamma}, the exponent determining the power-law dependence of the relaxation time on Q; <{tau}{sub 0}>, the Q-independent pre-factor for the average translational relaxation time; <{tau}{sub R{sub 1}}>, the relaxation time for the first-order rotational correlation function; and <{tau}{sub R{sub 3}}>, the relaxation time for the second-order rotational correlation function. We discuss the temperature dependence of these parameters and note that, in particular, the dynamics is rapidly slowing down at temperature around 220 K, signalling the onset of a structural arrest transition of liquid water into an amorphous solid water.

  13. 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.

  14. High-throughput Z T predictions of nanoporous bulk materials as next-generation thermoelectric materials: A material genome approach

    Science.gov (United States)

    Hao, Qing; Xu, Dongchao; Lu, Na; Zhao, Hongbo

    2016-05-01

    The advancement of computational tools for material property predictions enables a broad search of novel materials for various energy-related applications. However, challenges still exist in accurately predicting the mean free paths of electrons and phonons in a high-throughput frame for thermoelectric property predictions, which largely hinders the computation-driven material search for novel materials. In this work, this need is eliminated under the limit of reduced nanostructure size within a bulk material, in which these mean free paths are restricted by the nanostructure size. A criterion for Z T evaluation is proposed for general nanoporous bulk materials and is demonstrated with representative oxides.

  15. Research Update: Triblock copolymers as templates to synthesize inorganic nanoporous materials

    Science.gov (United States)

    Li, Yunqi; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke

    2016-04-01

    This review focuses on the application of triblock copolymers as designed templates to synthesize nanoporous materials with various compositions. Asymmetric triblock copolymers have several advantages compared with symmetric triblock copolymers and diblock copolymers, because the presence of three distinct domains can provide more functional features to direct the resultant nanoporous materials. Here we clearly describe significant contributions of asymmetric triblock copolymers, especially polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (abbreviated as PS-b-P2VP-b-PEO).

  16. The heat science of the nano-porous materials; La thermique des materiaux nanoporeux

    Energy Technology Data Exchange (ETDEWEB)

    Volz, S. [CNRS, Lab. d' Energetique Moleculaire et Macroscopique, Combustion, 92 - Chatenay Malabry (France); Quintard, M. [CNRS, Institut de Mecanique des Fluides, 31 - Toulouse (France); Rochais, D. [CEA Centre d' Etudes du Ripault, Lab. Microstructures et Comportements, 37 - Tours (France); Enguehard, F. [CEA Centre d' Etudes du Ripault, Lab. Ingenierie des Materiaux Optiques, 37 - Tours (France); Domingues, G. [Ecole Nationale Superieure de Mecanique et d' Aerotechnique (ENSMA), Lab. d' Etudes Thermiques, 86 - Poitiers (France); Quenard, D. [CSTB, Div. Caracterisation Physique des Materiaux, 38 - Grenoble (France); Rigacci, A. [Ecole des Mines de Paris, Centre Energetique et Procedes, 75 - Paris (France); Bourdin, V. [CNRS, Lab. d' Informatique pour la Mecanique et les Sciences pour l' Ingenieur, 91 - Orsay (France); Chantrenne, P. [Centre de Thermique de Lyon, INSA, 69 - Lyon (France)

    2005-07-01

    In this work are gathered the transparencies of the lecture presented at the conference 'the heat science of the nano-porous materials'. The titles of the different lectures are: 1)modelling of the transfers in nano-porous media 2)modelling of the transfers inside nano-porous super-insulators part I: conduction part II: radiation 3)heat transfers between two silicon oxide nano-crystallite 4)thermo-physical properties of two pyro-micro-nano-porous silicon oxides: humidity and temperature effect 5)adsorption kinetics by a thermal frequency method: an indirect measurement method of the effective conductivity of the granulated adsorbents 6)the aerogels materials: nano-structured thermal super-insulators 7)anticipation of the nano-structured silicon thermal conductivity. (O.M.)

  17. The Maxwell-Stefan description of mixture diffusion in nanoporous crystalline materials

    NARCIS (Netherlands)

    Krishna, R.

    2014-01-01

    The efficacy of nanoporous crystalline materials in separation applications is often influenced to a significant extent by diffusion of guest molecules within the pores of the structural frameworks. The Maxwell-Stefan (M-S) equations provide a fundamental and convenient description of mixture diffus

  18. The Tribological Efficiency and the Mechanism of Action of Nano-Porous Composition Base Brake Lining Materials

    Science.gov (United States)

    Kutelia, E. R.; Gventsadze, D. I.; Eristavil, B. G.; Maisuradze, N. I.; Tsurtsumia, O. O.; Gventsadze, L. D.; Olofsson, U.; Wahlström, J.; Olander, L.

    2011-12-01

    Based on the comparative analysis of the experimental values determined for the tribological parameters for the three novel nano-porous composition base and two conventional brake lining materials while friction with the grey cast iron disc, it was shown the considerable high tribological efficiency of the novel nano-porous composition base lining materials in comparison with the conventional (from EU and USA market) brake lining materials. The explanation is given to the action mechanism of nano-porous composition base brake lining material and its tribological efficiency basing on the "triple phase" tribo-pair model.

  19. The epistemology of Ludwik Fleck and the thought community of Banff: reflections on the classification of the renal allograft pathology.

    Science.gov (United States)

    Pena, G P

    2011-05-01

    Ludwik Fleck was a polish physician and bacteriologist with major interest in epistemology. In 1935, he published, in German, a monograph entitled 'Genesis and development of a scientific fact'. His concepts of 'thought collective', 'thought style' and 'active and passive associations' have been materialized in Banff classification of renal allograft pathology. The dynamics and evolution of the classification of renal allograft pathology, generated within Banff community, reflect perfectly Fleck's conceptions. In this essay, the Banff community of thought is characterized as a thought collective, according to Fleck's epistemology. Since its inception, the classification has been evolving in a continuum of active and passive connections, preserving its initial thought style, based on morphology. Whether the emergence of nonmorphological, molecular techniques will result in the end of morphological thought style is a question the community is presently facing.

  20. Advanced Nanoporous Materials for Micro-Gravimetric Sensing to Trace-Level Bio/Chemical Molecules

    OpenAIRE

    Pengcheng Xu; Xinxin Li; Haitao Yu; Tiegang Xu

    2014-01-01

    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-surfa...

  1. Mechanisms of material removal and mass transport in focused ion beam nanopore formation

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kallol, E-mail: das7@illinois.edu; Johnson, Harley T., E-mail: htj@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, MC-244, Urbana, Illinois 61801 (United States); Freund, Jonathan B., E-mail: jbfreund@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, MC-244, Urbana, Illinois 61801 (United States); Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street Urbana, Illinois 61801 (United States)

    2015-02-28

    Despite the widespread use of focused ion beam (FIB) processing as a material removal method for applications ranging from electron microscope sample preparation to nanopore processing for DNA sequencing, the basic material removal mechanisms of FIB processing are not well understood. We present the first complete atomistic simulation of high-flux FIB using large-scale parallel molecular dynamics (MD) simulations of nanopore fabrication in freestanding thin films. We focus on the root mechanisms of material removal and rearrangement and describe the role of explosive boiling in forming nanopores. FIB nanopore fabrication is typically understood to occur via sputter erosion. This can be shown to be the case in low flux systems, where individual ion impacts are sufficiently separated in time that they may be considered as independent events. But our detailed MD simulations show that in high flux FIB processing, above a threshold level at which thermal effects become significant, the primary mechanism of material removal changes to a significantly accelerated, thermally dominated process. Under these conditions, the target is heated by the ion beam faster than heat is conducted away by the material, leading quickly to melting, and then continued heating to nearly the material critical temperature. This leads to explosive boiling of the target material with spontaneous bubble formation and coalescence. Mass is rapidly rearranged at the atomistic scale, and material removal occurs orders of magnitude faster than would occur by simple sputtering. While the phenomenology is demonstrated computationally in silicon, it can be expected to occur at lower beam fluxes in other cases where thermal conduction is suppressed due to material properties, geometry, or ambient thermal conditions.

  2. Atomistic simulation of nanoporous layered double hydroxide materials and their properties. I. Structural modeling

    Science.gov (United States)

    Kim, Nayong; Kim, Yongman; Tsotsis, Theodore T.; Sahimi, Muhammad

    2005-06-01

    An atomistic model of layered double hydroxides, an important class of nanoporous materials, is presented. These materials have wide applications, ranging from adsorbents for gases and liquid ions to nanoporous membranes and catalysts. They consist of two types of metallic cations that are accommodated by a close-packed configuration of OH- and other anions in a positively charged brucitelike layer. Water and various anions are distributed in the interlayer space for charge compensation. A modified form of the consistent-valence force field, together with energy minimization and molecular dynamics simulations, is utilized for developing an atomistic model of the materials. To test the accuracy of the model, we compare the vibrational frequencies, x-ray diffraction patterns, and the basal spacing of the material, computed using the atomistic model, with our experimental data over a wide range of temperature. Good agreement is found between the computed and measured quantities.

  3. Catalytic pyrolysis of waste mandarin over nanoporous materials.

    Science.gov (United States)

    Park, Young-Kwon; Kim, Jeong Wook; Park, Sung Hoon; Kim, Seong-Soo; Jeon, Jong-Ki; Lee, See Hoon

    2013-01-01

    Catalytic pyrolysis of waste mandarin was performed using nanoporous catalysts. AI-MCM-41 and Meso-MFI, which had different acid characteristics, were used. In addition, the characteristics of Pt/Meso-MFI were compared with those of Meso-MFI. To analyze the characteristics of the catalyst samples, Brunauer-Emmett-Teller surface area, temperature programmed desorption of NH3, and N2 adsorption-desorption analyses were performed. In addition, pyrolysis gas chromatography/mass spectrometry was used to facilitate the direct analysis of the pyrolytic products. The products obtained from catalytic pyrolysis contained a greater amount of valuable components than did those obtained from non-catalytic pyrolysis, indicating that catalytic pyrolysis improved the quality of the bio-oil. Additionally, valuable products such as furan and aromatic compounds were produced in greater quantities when Meso-MFI was used. When Pt/Meso-MFI was used, the amounts of furan and aromatic compounds produced increased even further.

  4. Nanoporous silicon flakes as anode active material for lithium-ion batteries

    Science.gov (United States)

    Kim, Young-You; Lee, Jeong-Hwa; Kim, Han-Jung

    2017-01-01

    Nanoporous-silicon (np-Si) flakes were prepared using a combination of an electrochemical etching process and an ultra-sonication treatment and the electrochemical properties were studied as an anode active material for rechargeable lithium-ion batteries (LIBs). This fabrication method is a simple, reproducible, and cost effective way to make high-performance Si-based anode active materials in LIBs. The anode based on np-Si flakes exhibited a higher performances (lower capacity fade rate, stability and excellent rate capability at high C-rate) than the anode based on Si nanowires. The excellent performance of the np-Si flake anode was attributed to the hollowness (nanoporous structure) of the anode active material, which allowed it to accommodate a large volume change during cycling.

  5. Omnidirectional reflector using nanoporous SiO2 as a low-refractive-index material.

    Science.gov (United States)

    Xi, J Q; Ojha, Manas; Cho, Woojin; Plawsky, J L; Gill, W N; Gessmann, Th; Schubert, E F

    2005-06-15

    Triple-layer omnidirectional reflectors (ODRs) consisting of a semiconductor, a quarter-wavelength transparent dielectric layer, and a metal have high reflectivities for all angles of incidence. Internal ODRs (ambient material's refractive index n > 1.0) are demonstrated that incorporate nanoporous SiO2, a low-refractive-index material (n = 1.23), as well as dense SiO2 (n = 1.46). GaP and Ag serve as the semiconductor and the metal layer, respectively. Reflectivity measurements, including angular dependence, are presented. Calculated angle-integrated TE and TM reflectivities for ODRs employing nanoporous SiO2 are R(int)/TE = 99.9% and R(int)/TM = 98.9%, respectively, indicating the high potential of the ODRs for low-loss waveguide structures.

  6. Tunable Impedance Spectroscopy Sensors via Selective Nanoporous Materials.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina M.; Small, Leo J

    2017-09-01

    Impedance spectroscopy was leveraged to directly detect the sorption of I 2 by selective adsorption into nanoporous metal organic frameworks (MOF). Films of three different types of MOF frameworks, respectively, were drop cast onto platinum interdigitated electrodes, dried, and exposed to gaseous I 2 at 25, 40, or 70 C. The MOF frameworks varied in topology from small pores (equivalent to I 2 diameter) to large pore frameworks. The combination of the chemistry of the framework and pore size dictated quantity and kinetics of I 2 adsorption. Air, argon, methanol, and water were found to produce minimal changes in ZIF-8 impedance. Independent of MOF framework characteristics, all resultant sensors showed high response to I 2 in air. As an example of sensor output, I 2 was readily detected at 25 C in air within 720 s of exposure, using an un-optimized sensor geometry with a small pored MOF. Further optimization of sensor geometry, decreasing MOF film thicknesses and maximizing sensor capacitance, will enable faster detection of trace I 2 .

  7. Microscopic theory of hysteretic hydrogen adsorption in nanoporous materials.

    Science.gov (United States)

    Kang, Joongoo; Wei, Su-Huai; Kim, Yong-Hyun

    2010-02-10

    Understanding gas adsorption confined in nanoscale pores is a fundamental issue with broad applications in catalysis and gas storage. Recently, hysteretic H(2) adsorption was observed in several nanoporous metal-organic frameworks (MOFs). Here, using first-principles calculations and simulated adsorption/desorption isotherms, we present a microscopic theory of the enhanced adsorption hysteresis of H(2) molecules using the MOF Co(1,4-benzenedipyrazolate) [Co(BDP)] as a model system. Using activated H(2) diffusion along the small-pore channels as a dominant equilibration process, we demonstrate that the system shows hysteretic H(2) adsorption under changes of external pressure. For a small increase of temperature, the pressure width of the hysteresis, as well as the adsorption/desorption pressure, dramatically increases. The sensitivity of gas adsorption to temperature changes is explained by the simple thermodynamics of the gas reservoir. Detailed analysis of transient adsorption dynamics reveals that the hysteretic H(2) adsorption is an intrinsic adsorption characteristic in the diffusion-controlled small-pore systems.

  8. Pore REconstruction and Segmentation (PORES) method for improved porosity quantification of nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Van Eyndhoven, G., E-mail: geert.vaneyndhoven@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Kurttepeli, M. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Van Oers, C.J.; Cool, P. [Laboratory of Adsorption and Catalysis, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Bals, S. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Batenburg, K.J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Centrum Wiskunde and Informatica, Science Park 123, NL-1090 GB Amsterdam (Netherlands); Mathematical Institute, Universiteit Leiden, Niels Bohrweg 1, NL-2333 CA Leiden (Netherlands); Sijbers, J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium)

    2015-01-15

    Electron tomography is currently a versatile tool to investigate the connection between the structure and properties of nanomaterials. However, a quantitative interpretation of electron tomography results is still far from straightforward. Especially accurate quantification of pore-space is hampered by artifacts introduced in all steps of the processing chain, i.e., acquisition, reconstruction, segmentation and quantification. Furthermore, most common approaches require subjective manual user input. In this paper, the PORES algorithm “POre REconstruction and Segmentation” is introduced; it is a tailor-made, integral approach, for the reconstruction, segmentation, and quantification of porous nanomaterials. The PORES processing chain starts by calculating a reconstruction with a nanoporous-specific reconstruction algorithm: the Simultaneous Update of Pore Pixels by iterative REconstruction and Simple Segmentation algorithm (SUPPRESS). It classifies the interior region to the pores during reconstruction, while reconstructing the remaining region by reducing the error with respect to the acquired electron microscopy data. The SUPPRESS reconstruction can be directly plugged into the remaining processing chain of the PORES algorithm, resulting in accurate individual pore quantification and full sample pore statistics. The proposed approach was extensively validated on both simulated and experimental data, indicating its ability to generate accurate statistics of nanoporous materials. - Highlights: • An electron tomography reconstruction/segmentation method for nanoporous materials. • The method exploits the porous nature of the scanned material. • Validated extensively on both simulation and real data experiments. • Results in increased image resolution and improved porosity quantification.

  9. Final Report of Optimization Algorithms for Hierarchical Problems, with Applications to Nanoporous Materials

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Stephen G.

    2013-11-11

    The research focuses on the modeling and optimization of nanoporous materials. In systems with hierarchical structure that we consider, the physics changes as the scale of the problem is reduced and it can be important to account for physics at the fine level to obtain accurate approximations at coarser levels. For example, nanoporous materials hold promise for energy production and storage. A significant issue is the fabrication of channels within these materials to allow rapid diffusion through the material. One goal of our research is to apply optimization methods to the design of nanoporous materials. Such problems are large and challenging, with hierarchical structure that we believe can be exploited, and with a large range of important scales, down to atomistic. This requires research on large-scale optimization for systems that exhibit different physics at different scales, and the development of algorithms applicable to designing nanoporous materials for many important applications in energy production, storage, distribution, and use. Our research has two major research thrusts. The first is hierarchical modeling. We plan to develop and study hierarchical optimization models for nanoporous materials. The models have hierarchical structure, and attempt to balance the conflicting aims of model fidelity and computational tractability. In addition, we analyze the general hierarchical model, as well as the specific application models, to determine their properties, particularly those properties that are relevant to the hierarchical optimization algorithms. The second thrust was to develop, analyze, and implement a class of hierarchical optimization algorithms, and apply them to the hierarchical models we have developed. We adapted and extended the optimization-based multigrid algorithms of Lewis and Nash to the optimization models exemplified by the hierarchical optimization model. This class of multigrid algorithms has been shown to be a powerful tool for

  10. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Science.gov (United States)

    Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

    2014-11-01

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound.

  11. Nanoporous aerogel as a bacteria repelling hygienic material for healthcare environment

    Science.gov (United States)

    Oh, Jun Kyun; Kohli, Nandita; Zhang, Yuanzhong; Min, Younjin; Jayaraman, Arul; Cisneros-Zevallos, Luis; Akbulut, Mustafa

    2016-02-01

    Healthcare-associated infections (HAIs) caused by pathogenic bacteria are a worldwide problem and responsible for numerous cases of morbidity and mortality. Exogenous cross-contamination is one of the main mechanisms contributing to such infections. This work investigates the potential of hydrophobically modified nanoporous silica aerogel as an antiadhesive hygienic material that can inhibit exogenous bacterial contamination. Nanoporous silica aerogels were synthesized via sol-gel polymerization of tetraethyl orthosilicate and hydrophobized using trimethylsilyl chloride. Bacterial adhesion characteristics were evaluated via dip-inoculation in suspensions of Gram-negative Escherichia coli O157:H7 and Gram-positive Staphylococcus aureus. The attachment of E. coli O157:H7 and S. aureus to hydrophobic nanoporous silica aerogel (HNSA) was found to be significantly lower than that to hydrophilic and hydrophobic nonporous silica materials: 99.91% (E. coli O157:H7) and 99.93% (S. aureus) reduction in comparison to hydrophilic nonporous silica, and 82.95% (E. coli O157:H7) and 84.90% (S. aureus) reduction in comparison to hydrophobic nonporous silica. These results suggest that the use of HNSA as surfaces that come into contact with bacterial pathogens in the healthcare environment can improve bacterial hygiene, and therefore may reduce the rate of HAIs.

  12. Nanoporous aerogel as a bacteria repelling hygienic material for healthcare environment.

    Science.gov (United States)

    Oh, Jun Kyun; Kohli, Nandita; Zhang, Yuanzhong; Min, Younjin; Jayaraman, Arul; Cisneros-Zevallos, Luis; Akbulut, Mustafa

    2016-02-26

    Healthcare-associated infections (HAIs) caused by pathogenic bacteria are a worldwide problem and responsible for numerous cases of morbidity and mortality. Exogenous cross-contamination is one of the main mechanisms contributing to such infections. This work investigates the potential of hydrophobically modified nanoporous silica aerogel as an antiadhesive hygienic material that can inhibit exogenous bacterial contamination. Nanoporous silica aerogels were synthesized via sol-gel polymerization of tetraethyl orthosilicate and hydrophobized using trimethylsilyl chloride. Bacterial adhesion characteristics were evaluated via dip-inoculation in suspensions of Gram-negative Escherichia coli O157:H7 and Gram-positive Staphylococcus aureus. The attachment of E. coli O157:H7 and S. aureus to hydrophobic nanoporous silica aerogel (HNSA) was found to be significantly lower than that to hydrophilic and hydrophobic nonporous silica materials: 99.91% (E. coli O157:H7) and 99.93% (S. aureus) reduction in comparison to hydrophilic nonporous silica, and 82.95% (E. coli O157:H7) and 84.90% (S. aureus) reduction in comparison to hydrophobic nonporous silica. These results suggest that the use of HNSA as surfaces that come into contact with bacterial pathogens in the healthcare environment can improve bacterial hygiene, and therefore may reduce the rate of HAIs.

  13. Membranes from nanoporous 1D and 2D materials: A review of opportunities, developments, and challenges

    KAUST Repository

    Kim, Wun-gwi

    2013-12-01

    Membranes utilizing nanoporous one-dimensional (1D) and two-dimensional (2D) materials are emerging as attractive candidates for applications in molecular separations and related areas. Such nanotubular and nanolayered materials include carbon nanotubes, metal oxide nanotubes, layered zeolites, porous layered oxides, layered aluminophosphates, and porous graphenes. By virtue of their unique shape, size, and structure, they possess transport properties that are advantageous for membrane and thin film applications. These materials also have very different chemistry from more conventional porous 3D materials, due to the existence of a large, chemically active, external surface area. This feature also necessitates the development of innovative strategies to process these materials into membranes and thin films with high performance. This work provides the first comprehensive review of this emerging area. We first discuss approaches for the synthesis and structural characterization of nanoporous 1D and 2D materials. Thereafter, we elucidate different approaches for fabrication of membranes and thin films from these materials, either as multiphase (composite/hybrid) or single-phase membranes. The influence of surface chemistry and processing techniques on the membrane morphology is highlighted. We then discuss the applications of such membranes in areas relating to molecular transport and separation, e.g. gas and liquid-phase separations, water purification, and ion-conducting membranes. The review concludes with a discussion of the present outlook and some of the key scientific challenges to be addressed on the path to industrially applicable membranes containing nanoporous 1D and 2D materials. © 2013 Elsevier Ltd.

  14. Mathematical Tools for Discovery of Nanoporous Materials for Energy Applications

    Science.gov (United States)

    Haranczyk, M.; Martin, R. L.

    2015-01-01

    Porous materials such as zeolites and metal organic frameworks have been of growing importance as materials for energy-related applications such as CO2 capture, hydrogen and methane storage, and catalysis. The current state-of-the-art molecular simulations allow for accurate in silico prediction of materials' properties but the computational cost of such calculations prohibits their application in the characterisation of very large sets of structures, which would be required to perform brute-force screening. Our work focuses on the development of novel methodologies to efficiently characterize and explore this complex materials space. In particular, we have been developing algorithms and tools for enumeration and characterisation of porous material databases as well as efficient screening approaches. Our methodology represents a ensemble of mathematical methods. We have used Voronoi tessellation-based techniques to enable high-throughput structure characterisation, statistical techniques to perform comparison and screening, and continuous optimisation to design materials. This article outlines our developments in material design.

  15. Laser spectroscopy of gas confined in nanoporous materials

    CERN Document Server

    Svensson, Tomas

    2009-01-01

    We show that high-resolution laser spectroscopy can probe surface interactions of gas confined in nano-cavities of porous materials. We report on strong line broadening and unfamiliar lineshapes due to tight confinement, as well as signal enhancement due to multiple photon scattering. This new domain of laser spectroscopy constitute a challenge for the theory of collisions and spectroscopic lineshapes, and open for new ways of analyzing porous materials and processes taking place therein.

  16. Nanoporous Materials for the Onboard Storage of Natural Gas.

    Science.gov (United States)

    Kumar, K Vasanth; Preuss, Kathrin; Titirici, Maria-Magdalena; Rodríguez-Reinoso, Francisco

    2017-02-08

    Climate change, global warming, urban air pollution, energy supply uncertainty and depletion, and rising costs of conventional energy sources are, among others, potential socioeconomic threats that our community faces today. Transportation is one of the primary sectors contributing to oil consumption and global warming, and natural gas (NG) is considered to be a relatively clean transportation fuel that can significantly improve local air quality, reduce greenhouse-gas emissions, and decrease the energy dependency on oil sources. Internal combustion engines (ignited or compression) require only slight modifications for use with natural gas; rather, the main problem is the relatively short driving distance of natural-gas-powered vehicles due to the lack of an appropriate storage method for the gas, which has a low energy density. The U.S. Department of Energy (DOE) has set some targets for NG storage capacity to obtain a reasonable driving range in automotive applications, ruling out the option of storing methane at cryogenic temperatures. In recent years, both academia and industry have foreseen the storage of natural gas by adsorption (ANG) in porous materials, at relatively low pressures and ambient temperatures, as a solution to this difficult problem. This review presents recent developments in the search for novel porous materials with high methane storage capacities. Within this scenario, both carbon-based materials and metal-organic frameworks are considered to be the most promising materials for natural gas storage, as they exhibit properties such as large surface areas and micropore volumes, that favor a high adsorption capacity for natural gas. Recent advancements, technological issues, advantages, and drawbacks involved in natural gas storage in these two classes of materials are also summarized. Further, an overview of the recent developments and technical challenges in storing natural gas as hydrates in wetted porous carbon materials is also included

  17. Nanoporous gold: a new material for catalytic and sensor applications.

    Science.gov (United States)

    Wittstock, Arne; Biener, Jürgen; Bäumer, Marcus

    2010-10-28

    Nanostructured materials are governed by their surface chemical properties. This is strikingly reflected by np-Au. This material can be generated by corrosion of bulk Ag-Au alloys. Based on a self-organisation process, a 3 dimensional sponge like gold structure evolves with ligaments in the range of only a few tens of nanometers. Due to its continuous porosity, the material can be penetrated by gases which then adsorb and interact with the surface. In this perspective we will review potential applications of np-Au resulting from this effect, namely heterogeneous gas phase catalysis, surface chemistry driven actuation, and adsorbate controlled stability of the nanostructure. We will summarize the current knowledge about the low temperature oxidation of CO as well as the highly selective oxidation of methanol. Furthermore, we will address the question how surface chemistry can influence the material properties itself. In particular, we will deal with (a) the actuation of np-Au by the reversible oxidation of its surface using ozone and (b) the adsorbate controlled coarsening of ligaments, using annealing experiments under ozone or inert gas atmosphere.

  18. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications

    DEFF Research Database (Denmark)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-01-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof...... of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(l-Lactic Acid) (PLLA) were confined within the 14nm pores of a NP with gyroid morphology...

  19. Enhanced transport of materials into enamel nanopores via electrokinetic flow.

    Science.gov (United States)

    Gan, H Y; Sousa, F B; Carlo, H L; Maciel, P P; Macena, M S; Han, J

    2015-04-01

    The ability to infiltrate various molecules and resins into dental enamel is highly desirable in dentistry, yet transporting materials into dental enamel is limited by the nanometric scale of their pores. Materials that cannot be infiltrated into enamel by diffusion/capillarity are often considered molecules with sizes above a critical threshold, which are often considered to be larger than the pores of enamel. We challenge this notion by reporting the use of electrokinetic flow to transport solutions with molecules with sizes above a critical threshold-namely, an aqueous solution with a high refractive index (Thoulet's solution) and a curable fluid resin infiltrant (without acid etching)-deep into the normal enamel layer. Volume infiltration by Thoulet's solution is increased by 5- to 6-fold, and resin infiltration depths as large as 600 to 2,000 µm were achieved, in contrast to ~10 µm resulting from diffusion/capillarity. Incubation with demineralization solution for 192 h resulted in significant demineralization at noninfiltrated histologic points but not at resin infiltrated. These results open new avenues for the transport of materials in dental enamel. © International & American Associations for Dental Research 2015.

  20. 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.

  1. Preparation of Nano-porous Materials(Ⅰ) by Polymerization of Amphiphile Self-assemblies

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The polymerization of amphiphilic self-assemblies is a promising method to synthesize nano-structured materials with novel properties. These materials have many attractive features for their application in biomedical area and materials science, such as catalysis, separation, surface modification, and therapeutics areas. A general review on the polymerization of lipids and surfactant self-assemblies to amphiphilic self-assemblies is given in this paper with 49 参考文献. The polymerization and the subsequently resulted structure of lipids in different morphologies are summarized. The polymerization of polymerizable surfactants(surfmers) in emulsion and liquid crystalline phases are also discussed. The potential application of new nano-porous materials is briefly described.

  2. Immobilization of enzyme (DAAO) on hybrid nanoporous MCF, SBA-15, and MCM-41 materials

    Science.gov (United States)

    Phi, Tien Q.; Le, Hy G.; Vu, Tuan A.; Phan, Thao T. H.; Pham, Huyen T.; Dao, Canh Duc; Dang, Phuong T.

    2011-12-01

    Hybrid nanoporous MCF, SBA-15 and MCM-41 materials were synthesized via hydrothermal treatment and functionalized with 3-aminopropyltriethoxysilane (APTES) via post-synthesis grafting and sequently activated by glutardialdehyde and then were used to immobilize D-amino acid oxidase (DAAO). The amino-functionalized materials were characterized by various techniques: XRD, IR and N2 adsorption-desorption (BET). From characterization results, it indicated that these materials still maintained their structure after functionalization. The data IR and TGA-DTA analysis demonstrated the incorpotation of amine functional groups on the surface of APTES-functionalized samples. The DAAO immobilized on functionalized materials exhibited higher catalytic activity and stability for conversion of cephalosporin C (CPC) compare to those of non-functionalized one. Further more, the catalytic activity as well as stability of enzyme decreased in order MCF > SBA-15 > MCM-41 with the decrease of their pore size.

  3. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Margarita, E-mail: mpopova@orgchem.bas.bg [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Szegedi, Agnes [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Mavrodinova, Vesselina [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Novak Tušar, Natasa [National Institute of Chemistry, Ljubljana (Slovenia); Mihály, Judith; Klébert, Szilvia [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Benbassat, Niko; Yoncheva, Krassimira [Faculty of Pharmacy, 2 Dunav Str., 1000 Sofia (Bulgaria)

    2014-11-15

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol.

  4. A universal model for nanoporous carbon supercapacitors applicable to diverse pore regimes, carbon materials, and electrolytes.

    Science.gov (United States)

    Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent

    2008-01-01

    Supercapacitors, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy-storage device with the potential to substitute batteries in applications that require high power densities. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we propose a heuristic theoretical model that takes pore curvature into account as a replacement for the EDLC model, which is based on a traditional parallel-plate capacitor. When the pore size is in the mesopore regime (2-50 nm), counterions enter mesoporous carbon materials and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (50 nm) at which pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced naturally to the EDLC model. We present density functional theory calculations and detailed analyses of available experimental data in various pore regimes, which show the significant effects of pore curvature on the supercapacitor properties of nanoporous carbon materials. It is shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials, including activated carbon materials, template carbon materials, and novel carbide-derived carbon materials, and with diverse electrolytes, including organic electrolytes, such as tetraethylammonium tetrafluoroborate (TEABF(4)) and tetraethylammonium methylsulfonate (TEAMS) in acetonitrile, aqueous H(2)SO(4) and KOH electrolytes, and even an ionic liquid electrolyte, such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI). The EDCC/EWCC model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size It may lend support for the systematic optimization of the properties of carbon supercapacitors through experiments. On the basis of the insight

  5. Facile mass production of nanoporous SnO2 nanosheets as anode materials for high performance lithium-ion batteries.

    Science.gov (United States)

    Wei, Wenli; Du, Pengcheng; Liu, Dong; Wang, Hongxing; Liu, Peng

    2017-10-01

    Facile one-step ultrasonic-assisted chemical precipitation strategy has been developed for the mass production of SnO2 nanomaterials with different morphologies. As anode material for lithium-ion batteries, the nanoporous SnO2 nanosheets exhibited an extremely high initial specific capacity of 2231mAh/g in comparison with 1242mAh/g of the SnO2 microcrystals and 1244mAh/g of the nanoporous SnO2 nanoflowers. Meanwhile the nanoporous SnO2 nanosheet electrode displayed a specific capacity of 688mAh/g after 60 cycles at 0.2 A/g current density and an extraordinary capacity retention of 224mAh/g at a current density of 8A/g (approximately 10 C) owing to a huge increase of Li(+) diffusion coefficient. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Investigating the relative influences of molecular dimensions and binding energies on diffusivities of guest species inside nanoporous crystalline materials

    NARCIS (Netherlands)

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

    2012-01-01

    The primary objective of this article is to investigate the relative influences of molecular dimensions and adsorption binding energies on unary diffusivities of guest species inside nanoporous crystalline materials such as zeolites and metal-organic frameworks (MOFs). The investigations are based o

  7. Designed synthesis of MOF-derived magnetic nanoporous carbon materials for selective enrichment of glycans for glycomics analysis.

    Science.gov (United States)

    Sun, Nianrong; Zhang, Xiangmin; Deng, Chunhui

    2015-04-21

    In this work, magnetic nanoporous carbon (NPC) materials were synthesized by choosing a MOF as a sacrificial template and a carbon precursor. The obtained Co-ZIF-67 materials showed strong magnetic response, high surface area, a uniform size of mesopores and high carbon content. The Co-ZIF-67 materials were successfully applied to glycomics analysis by enriching N-linked glycans in bio-samples with high selectivity and efficiency.

  8. Confinement of MgH2 nanoclusters within nanoporous aerogel scaffold materials.

    Science.gov (United States)

    Nielsen, Thomas K; Manickam, Kandavel; Hirscher, Michael; Besenbacher, Flemming; Jensen, Torben R

    2009-11-24

    Nanoparticles of magnesium hydride were embedded in nanoporous carbon aerogel scaffold materials in order to explore the kinetic properties of hydrogen uptake and release. A new modified procedure for the synthesis of magnesium hydride nanoparticles is presented. The procedure makes use of monoliths (approximately 0.4 cm(3)) of two distinct types of nanoporous resorcinol-formaldehyde carbon aerogels loaded with dibutylmagnesium, MgBu(2). Excess MgBu(2) was removed mechanically, and the increase in mass was used as a measure of the amount of embedded MgH(2). Energy-dispersive spectrometry revealed that MgH(2) was uniformly distributed within the aerogel material. In situ synchrotron radiation powder X-ray diffraction showed that MgBu(2) transformed directly to MgH(2) at T approximately 137 degrees C and p(H(2)) = 50 bar. Two distinct aerogel samples, denoted X1 and X2, with pore volumes of 1.27 and 0.65 mL/g and average pore sizes of 22 and 7 nm, respectively, were selected. In these samples, the uptake of magnesium hydride was found to be proportional to the pore volume, and aerogels X1 and X2 incorporated 18.2 and 10.0 wt % of MgH(2), respectively. For the two samples, the volumetric MgH(2) uptake was similar, approximately 12 vol %. The hydrogen storage properties of nanoconfined MgH(2) were studied by Sieverts' measurements and thermal desorption spectroscopy, which clearly demonstrated that the dehydrogenation kinetics of the confined hydride depends on the pore size distribution of the scaffold material; that is, smaller pores mediated faster desorption rates possibly due to a size reduction of the confined magnesium hydride.

  9. Building Nanoporous Metal-Organic Frameworks "Armor" on Fibers for High-Performance Composite Materials.

    Science.gov (United States)

    Yang, Xiaobin; Jiang, Xu; Huang, Yudong; Guo, Zhanhu; Shao, Lu

    2017-02-15

    The nanoporous metal-organic frameworks (MOFs) "armor" is in situ intergrown onto the surfaces of carbon fibers (CFs) by nitric acid oxidization to supply nucleation sites and serves as a novel interfacial linker between the fiber and polymer matrix and a smart cushion to release interior and exterior applied forces. Simultaneous enhancements of the interfacial and interlaminar shear strength as well as the tensile strength of CFs were achieved. With the aid of an ultrasonic "cleaning" process, the optimized surface energy and tensile strength of CFs with a MOF "armor" are 83.79 mN m(-1) and 5.09 GPa, for an increase of 102% and 11.6%, respectively. Our work finds that the template-induced nucleation of 3D MOF onto 1D fibers is a general and promising approach toward advanced composite materials for diverse applications to meet scientific and technical demands.

  10. Nanoporous materials for hydrogen storage and H{sub 2}/D{sub 2} isotope separation

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Hyunchul

    2014-05-05

    This thesis presents a study of hydrogen adsorption properties at RT with noble metal doped porous materials and an efficient separation of hydrogen isotopes with nanoporous materials. Most analysis is performed via thermal desorption spectra (TDS) and Sieverts-type apparatus. The result and discussion is presented in two parts; Chapter 4 focuses on metal doped nanoporous materials for hydrogen storage. Cryogenic hydrogen storage by physisorption on porous materials has the advantage of high reversibility and fast refuelling times with low heat evolution at modest pressures. At room temperature, however, the physisorption mechanism is not abEle to achieve enough capacity for practical application due to the weak van der Waals interaction, i.e., low isosteric heats for hydrogen sorption. Recently, the ''spillover'' effect has been proposed by R. Yang et al. to enhance the room temperature hydrogen storage capacity. However, the mechanism of this storage enhancement by decoration of noble metal particles inside high surface area supports is not yet fully understood and still under debate. In this chapter, noble metal (Pt / Pd) doped nanoporous materials (i.e. porous carbon, COFs) have been investigated for room temperature hydrogen storage. Their textural properties and hydrogen storage capacity are characterized by various analytic techniques (e.g. SEM, HRTEM, XRD, BET, ICP-OES, Thermal desorption spectra, Sievert's apparatus and Raman spectroscopy). Firstly, Pt-doped and un-doped templated carbons possessing almost identical textural properties were successfully synthesized via a single step wet impregnation method. This enables the study of Pt catalytic activities and hydrogen adsorption kinetics on porous carbons at ambient temperature by TDS after H{sub 2}/D{sub 2} gas exposure and PCT measurement, respectively. While the H{sub 2} adsorption kinetics in the microporous structure is enhanced by Pt catalytic activities (spillover), only a

  11. Design of Stratified Functional Nanoporous Materials for CO2 Capture and Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J. Karl [University of Pittsburgh; Ye, Jingyun [University of Pittsburgh

    2017-10-03

    The objective of this project is to develop novel nanoporous materials for CO2 capture and conversion. The motivation of this work is that capture of CO2 from flue gas or the atmosphere coupled with catalytic hydrogenation of CO2 into valuable chemicals and fuels can reduce the net amount of CO2 in the atmosphere while providing liquid transportation fuels and other commodity chemicals. One approach to increasing the economic viability of carbon capture and conversion is to design a single material that can be used for both the capture and catalytic conversion of CO2, because such a material could increase efficiency through process intensification. We have used density functional theory (DFT) methods to design catalytic moieties that can be incorporated into various metal organic framework (MOF) materials. We chose to work with MOFs because they are highly tailorable, can be functionalized, and have been shown to selectively adsorb CO2 over N2, which is a requirement for CO2 capture from flue gas. Moreover, the incorporation of molecular catalytic moieties into MOF, through covalent bonding, produces a heterogeneous catalytic material having activities and selectivities close to those of homogeneous catalysts, but without the draw-backs associated with homogeneous catalysis.

  12. Sodium Dodecyl Sulfate (SDS)-Loaded Nanoporous Polymer as Anti-Biofilm Surface Coating Material

    DEFF Research Database (Denmark)

    Li, Li; Molin, Søren; Yang, Liang

    2013-01-01

    -b-polydimethylsiloxane (1,2-PB-b-PDMS) block copolymer via chemical cross-linking of the 1,2-PB block followed by quantitative removal of the PDMS block. Sodium dodecyl sulfate (SDS) was loaded into the nanoporous 1,2-PB from aqueous solution. The SDS-loaded nanoporous polymer films were shown to block bacterial attachment...

  13. Strategies for Hydrogen Storage in Nanoporous Metal-Organic Framework Materials

    Science.gov (United States)

    Snurr, Randall

    2011-03-01

    Storing hydrogen by physisorption in porous materials is a challenging problem of great interest for future vehicle technology. Metal-organic frameworks (MOFs) are a new class of nanoporous materials that have demonstrated exciting potential for solving this problem. MOFs are synthesized by the self-assembly of metal nodes and connecting organic linker molecules to create stable, porous frameworks. The synthetic chemistry opens the possibility to create an almost unlimited number of MOFs and to tailor them for particular applications, such as hydrogen storage. The diversity of MOFs also creates an opportunity to learn more about the fundamentals of hydrogen adsorption in porous materials. We have used a combination of classical Monte Carlo simulations and quantum mechanical approaches to investigate fundamental questions about hydrogen storage in MOFs and to design new materials with improved storage capabilities. Relationships have been elucidated between hydrogen uptake and properties such as the MOF surface area, void volume, degree of catenation, enthalpy of adsorption, and cation content. Introduction of cations is a promising strategy to improve hydrogen uptake at room temperature, and different metal cations and different strategies for introducing them into MOFs have been screened computationally.

  14. Cross-Linked Nanoporous Materials from Reactive and Multifunctional Block Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Myungeun; Amendt, Mark A.; Hillmyer, Marc A. (UMM)

    2012-10-10

    Polylactide-b-poly(styrene-co-2-hydroxyethylmethacrylate) (PLA-b-P(S-co-HEMA)) and polylactide-b-poly(styrene-co-2-hydroxyethylacrylate) (PLA-b-P(S-co-HEA)) were synthesized by combination of ring-opening polymerization and reversible addition-fragmentation chain transfer polymerization. {sup 1}H nuclear magnetic resonance spectroscopy and size exclusion chromatography data indicated that the polymerizations were controlled and that hydroxyl groups were successfully incorporated into the block polymers. The polymers were reacted with 4,4{prime}-methylenebis(phenyl isocyanate) (MDI) to form the corresponding cross-linked materials. The materials were annealed at 150 C to complete the coupling reaction. Robust nanoporous materials were obtained from the cross-linked polymers by treatment with aqueous base to hydrolyze the PLA phase. Small-angle X-ray scattering study combined with scanning electron microscopy showed that MDI-cross-linked PLA-b-P(S-co-HEMA)/PLA-b-P(S-co-HEA) can adopt lamellar, hexagonally perforated lamellar, and hexagonally packed cylindrical morphologies after annealing. In particular, the HPL morphology was found to evolve from lamellae due to increase in volume fraction of PS phase as MDI reacted with hydroxyl groups. The reaction also kinetically trapped the morphology by cross-linking. Bicontinuous morphologies were also observed when dibutyltin dilaurate was added to accelerate reaction between the polymer and MDI.

  15. Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor

    Science.gov (United States)

    2013-01-01

    Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level. PMID:23497184

  16. Single molecule sensing with solid-state nanopores: novel materials, methods, and applications.

    Science.gov (United States)

    Miles, Benjamin N; Ivanov, Aleksandar P; Wilson, Kerry A; Doğan, Fatma; Japrung, Deanpen; Edel, Joshua B

    2013-01-07

    This tutorial review will introduce and explore the fundamental aspects of nanopore (bio)sensing, fabrication, modification, and the emerging technologies and applications that both intrigue and inspire those working in and around the field. Although nanopores can be classified into two categories, solid-state and biological, they are essentially two sides of the same coin. For instance, both garner popularity due to their ability to confine analytes of interest to a nanoscale volume. Due to the vast diversity of nanopore platforms and applications, no single review can cover the entire landscape of published work in the field. Therefore, in this article focus will be placed on recent advancements and developments taking place in the field of solid-state nanopores. It should be stated that the intention of this tutorial review is not to cite all articles relating to solid-state nanopores, but rather to highlight recent, select developments that will hopefully benefit the new and seasoned scientist alike. Initially we begin with the fundamentals of solid-state nanopore sensing. Then the spotlight is shone on the sophisticated fabrication methods that have their origins in the semiconductor industry. One inherent advantage of solid-state nanopores is in the ease of functionalizing the surface with a range of molecules carrying functional groups. Therefore, an entire section is devoted to highlighting various chemical and bio-molecular modifications and explores how these permit the development of novel sensors with specific targets and functions. The review is completed with a discussion on novel detection strategies using nanopores. Although the most popular mode of nanopore sensing is based upon what has come to be known as ionic-current blockade sensing, there is a vast, growing literature based around exploring alternative detection techniques to further expand on the versatility of the sensors. Such techniques include optical, electronic, and force based methods

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

    Science.gov (United States)

    Heydari, Hamid; Moosavifard, Seyyed Ebrahim; Elyasi, Saeed; Shahraki, Mohammad

    2017-02-01

    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 m2 g-1) and nanoscale shell thickness (nano-hollow spheres electrode exhibits excellent electrochemical performance including a maximum specific capacitance of 948 F g-1 at 1 A g-1, significant rate capability of 46% capacitance retention at a high current density of 50 A g-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.

  18. 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.

  19. The Influence of Pore Size on the Indentation Behavior of Metallic Nanoporous Materials: A Molecular Dynamics Study

    Directory of Open Access Journals (Sweden)

    Daniel Esqué-de los Ojos

    2016-05-01

    Full Text Available In general, the influence of pore size is not considered when determining the Young’s modulus of nanoporous materials. Here, we demonstrate that the pore size needs to be taken into account to properly assess the mechanical properties of these materials. Molecular dynamics simulations of spherical indentation experiments on single crystalline nanoporous Cu have been undertaken in systems with: (i a constant degree of porosity and variable pore diameter; and (ii a constant pore diameter and variable porosity degree. The classical Gibson and Ashby expression relating Young’s modulus with the relative density of the nanoporous metal is modified to include the influence of the pore size. The simulations reveal that, for a fixed porosity degree, the mechanical behavior of materials with smaller pores differs more significantly from the behavior of the bulk, fully dense counterpart. This effect is ascribed to the increase of the overall surface area as the pore size is reduced, together with the reduced coordination number of the atoms located at the pores edges.

  20. The Influence of Pore Size on the Indentation Behavior of Metallic Nanoporous Materials: A Molecular Dynamics Study.

    Science.gov (United States)

    Esqué-de Los Ojos, Daniel; Pellicer, Eva; Sort, Jordi

    2016-05-11

    In general, the influence of pore size is not considered when determining the Young's modulus of nanoporous materials. Here, we demonstrate that the pore size needs to be taken into account to properly assess the mechanical properties of these materials. Molecular dynamics simulations of spherical indentation experiments on single crystalline nanoporous Cu have been undertaken in systems with: (i) a constant degree of porosity and variable pore diameter; and (ii) a constant pore diameter and variable porosity degree. The classical Gibson and Ashby expression relating Young's modulus with the relative density of the nanoporous metal is modified to include the influence of the pore size. The simulations reveal that, for a fixed porosity degree, the mechanical behavior of materials with smaller pores differs more significantly from the behavior of the bulk, fully dense counterpart. This effect is ascribed to the increase of the overall surface area as the pore size is reduced, together with the reduced coordination number of the atoms located at the pores edges.

  1. Sodium Dodecyl Sulfate (SDS-Loaded Nanoporous Polymer as Anti-Biofilm Surface Coating Material

    Directory of Open Access Journals (Sweden)

    Sokol Ndoni

    2013-02-01

    Full Text Available Biofilms cause extensive damage to industrial settings. Thus, it is important to improve the existing techniques and develop new strategies to prevent bacterial biofilm formation. In the present study, we have prepared nanoporous polymer films from a self-assembled 1,2-polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS block copolymer via chemical cross-linking of the 1,2-PB block followed by quantitative removal of the PDMS block. Sodium dodecyl sulfate (SDS was loaded into the nanoporous 1,2-PB from aqueous solution. The SDS-loaded nanoporous polymer films were shown to block bacterial attachment in short-term (3 h and significantly reduce biofilm formation in long-term (1 week by gram-negative bacterium Escherichia coli. Tuning the thickness or surface morphology of the nanoporous polymer films allowed to extent the anti-biofilm capability.

  2. Atomistic simulation of nanoporous layered double hydroxide materials and their properties. II. Adsorption and diffusion

    Science.gov (United States)

    Kim, Nayong; Harale, Aadesh; Tsotsis, Theodore T.; Sahimi, Muhammad

    2007-12-01

    Nanoporous layered double hydroxide (LDH) materials have wide applications, ranging from being good adsorbents for gases (particularly CO2) and liquid ions to membranes and catalysts. They also have applications in medicine, environmental remediation, and electrochemistry. Their general chemical composition is [M1-xIIMxIII(OH-)2]x+[Xn/mm -•nH2O], where M represents a metallic cation (of valence II or III), and Xn/mm - is an m-valence inorganic, or heteropolyacid, or organic anion. We study diffusion and adsorption of CO2 in a particular LDH with MII=Mg, MIII=Al, and x ≃0.71, using an atomistic model developed based on energy minimization and molecular dynamics simulations, together with a modified form of the consistent-valence force field. The adsorption isotherms and self-diffusivity of CO2 in the material are computed over a range of temperature, using molecular simulations. The computed diffusivities are within one order of magnitude of the measured ones at lower temperatures, while agreeing well with the data at high temperatures. The measured and computed adsorption isotherms agree at low loadings, but differ by about 25% at high loadings. Possible reasons for the differences between the computed properties and the experimental data are discussed, and a model for improving the accuracy of the computed properties is suggested. Also studied are the material's hydration and swelling properties. As water molecules are added to the pore space, the LDH material swells to some extent, with the hydration energy exhibiting interesting variations with the number of the water molecules added. The implications of the results are discussed.

  3. THE IMPACT OF THE SURFACE MORPHOLOGY ON ENERGY CHARACTERISTICS OF NANOPOROUS CARBON MATERIAL

    Directory of Open Access Journals (Sweden)

    B.K. Ostafiychuk

    2014-05-01

    Full Text Available The impact of nanoporous carbon material (PCM morphology on its electrochemical behavior in aqueous electrolyte has been studied. The optimum concentration of aqueous lithium sulfate which provides the maximum specific energy characteristics of capacitor-type systems C/Li2SO4/C is determined. Capacitive parameters of electrochemical capacitors (EC in aqueous so­lutions of lithium, sodium and potassium sulfate which have different molar ratio have been stu­died by comparative analysis. Cyclic voltammograms at different scan rates show that the PCM ca­pacitive behavior in three electrolytes increases in the following order Li2SO4

  4. Removal of Cr(VI Species from Aqueous Solution by Different Nanoporous Materials

    Directory of Open Access Journals (Sweden)

    Mohammad Ghashghaee

    2016-10-01

    Full Text Available Background: The removal of toxic metals from sewage and wastewaters is one of the most important concerns in the twenty first century. The removal of poisonous Cr(VI from aqueous solution by different low-cost available nanoporous adsorbents was investigated in the present study. Methods: Fumed silica, bentonite (BN, hydrotalcite (HT, MCM-41, Na-Y, mordenite (MOR and SAPO-34 were used at different adsorbent-to-metal ion ratios. Two predominant species of Cr were considered including chromate and hydrogen chromate ions. Results: Both HT and Na-Y adsorbed the toxic bichromate ions more favorably than other sorbents. Overall, the efficiency of the Cr removal followed the sequence of HT > SAPO-34 > MOR > MCM-41 > Na-Y > silica > BN. Because of its surface chemistry, HT with an uptake of 65.2 mg/g showed the highest toxic abatement among the seven adsorbents investigated under the acidic conditions, followed by the microporous materials SAPO-34 and MOR with uptakes of 41.2 and 41.0 mg/g, respectively. Conclusion: Both HT and Na-Y adsorbed the toxic bichromate ions more favorably than other sorbents. The high pore volume and the apparent surface area of a non-functionalized MCM-41 were not effective in the adsorption of Cr compounds. Overall, HT was the best choice owing to its appropriate surface chemistry with respect to the Cr oxygenates.

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

    Science.gov (United States)

    Krishna, Rajamani; van Baten, Jasper M

    2013-06-07

    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 frameworks (ZIFs). For cage-type structures (e.g. LTA, CHA, DDR, and ZIF-8), the variation of the free energy barrier for inter-cage hopping across the narrow windows, -δFi, provides a rationalization of the observed strong influence of pore concentrations, ci, on diffusivities. In open structures with large pore volumes (e.g. FAU, IRMOF-1, CuBTC) and within channels (MFI, BEA, MgMOF-74, MIL-47, MIL-53), the pore concentration (ci) dependence of the self- (Di,self), Maxwell-Stefan (Đi), and Fick (Di) diffusivities are often strongly dictated by the inverse thermodynamic correction factor, 1/Γi≡∂ln ci/∂ln pi; the magnitudes of the diffusivities are dictated by the binding energies for adsorption. For many guest-host combinations Đi-ci dependence is directly related to the 1/Γivs. ci variation. When molecular clustering occurs, we get 1/Γi > 1, causing unusual Đivs. ci dependencies. The match, or mis-match, between the periodicity of the pore landscape and the conformations of adsorbed chain molecules often leads to non-monotonic variation of diffusivities with chain lengths.

  6. Photovoltaic performance of nanoporous TiO2 replicas synthesized from mesoporous materials for dye-sensitized solar cells.

    Science.gov (United States)

    Hwang, Kyung-Jun; Yoo, Seung-Joon; Kim, Sung-Soo; Kim, Ji-Man; Shim, Wang-Geun; Kim, Sun-Il; Lee, Jae-Wook

    2008-10-01

    For dye-sensitized solar cell (DSSC), highly ordered nanoporous TiO2 materials with crystalline frameworks were successfully synthesized from different silica templates including SBA-15, KIT-6 and MSU-H. A photoelectrode in DSSC was fabricated by adsorbing cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) onto the prepared TiO2 nanoparticles. The samples were characterized by XRD, TEM, FE-SEM, AFM and Brunauer-Emmett-Teller (BET), and FT-IR analysis. An investigation of the influence of the bonding structure of N719 dye and nanoporous TiO2 on the photovoltaic performance of DSSC revealed that the bonding structure of N719 on TiO2 films is caused by the unidentate and bidentate linkage. Based on the overall conversion efficiency (eta), fill factor (FF), open-circuit voltage (V(oc)) and short-circuit current (/sc) from the I-V curves measured, it was observed that the photoelectric performance is strongly dependent on the dispersion properties of the nanoporous TiO2 replicas from mesoporous silica templates.

  7. Determination of Polycyclic Aromatic Hydrocarbons in Water Using Nanoporous Material Prepared from Waste Avian Egg Shell

    Directory of Open Access Journals (Sweden)

    Abdulmumin A. Nuhu

    2012-01-01

    Full Text Available For the first time a biocompatible calcium carbonate vateritic polymorph was recrystallized from eggshell waste and its application for the extraction of polycyclic aromatic hydrocarbons in water samples was demonstrated. This nanoporous calcium carbonate was used as sorbent in dispersive micro-solid-phase extraction method. In this approach 50 mg of the calcium carbonate material having about 25 nm pores was placed in a 5 mL of water sample and ultrasonicated for 30 min. The cloudy sample was centrifuged at 13500 rpm for 2 min. The aqueous layer was then discarded and the CaCO3 material was dabbed dry with a lint-free tissue. The analytes were then desorbed with 100 μL of dichloromethane by ultrasonication for 5 min. Finally, the extract was analyzed by gas chromatography flame ionization detector. Experimental parameters affecting the extraction recoveries were optimized. Using optimum extraction conditions, calibration curves were linear with correlation coefficients of 0.9853 to 0.9973 over the concentration range of 0.05 to 30 ng/mL. This method showed a detection limit as low as 0.004 ng/mL (at signal-to-noise ratio of 3. Performance of the dispersive micro-solid-phase extraction was compared with a previously optimized solid-phase extraction technique. The developed method displayed good extraction recoveries (85 ± 8–110 ± 4% with high enhancement factors (388–1433-fold and good repeatability (% RSD < 13 and involved the use of minimal solvents. Analysis of seawater from Dammam Port revealed the presence of the analytes at concentrations between 0.15±0.01 and 13.43±1.54 ng/mL.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Hydrogen-storage materials dispersed into nanoporous substrates studied through incoherent inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Colognesi, D., E-mail: daniele.colognesi@fi.isc.cnr.it [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Ulivi, L.; Zoppi, M. [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Ramirez-Cuesta, A.J. [ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Orecchini, A. [Institut Laue-Langevin, 6 Rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Karkamkar, A.J. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Fichtner, M.; Gil Bardaji, E.; Zhao-Karger, Z. [Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76347 Eggenstein-Leopoldshafen (Germany)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Densities of phonon states in some infiltrated H-storage materials are measured. Black-Right-Pointing-Pointer Signatures induced by the infiltration process on NaAlH{sub 4} phonon bands are detected. Black-Right-Pointing-Pointer Weaker modifications are found in MgH{sub 2} and NH{sub 3}BH{sub 3}, mainly in the low-energy region. Black-Right-Pointing-Pointer No relevant effect has been observed in LiBH{sub 4} + Mg(BH{sub 4}){sub 2}. - Abstract: Incoherent inelastic neutron scattering measurements on four impregnated/infiltrated composites of hydrides (namely, NaAlH{sub 4}, NH{sub 3}BH{sub 3}, LiBH{sub 4} + Mg(BH{sub 4}){sub 2}, and MgH{sub 2}) plus nanoporous scaffolds (active carbon fibers or silica-based MCM41) have been performed at low temperature. After a careful data analysis, the present experimental results have been compared to the corresponding spectroscopic data of bulk hydrides. Evident signatures induced by infiltration process on the NaAlH{sub 4} phonon bands have been detected, showing up as a strong peak broadening and smoothing together with, in some cases, an energy shift. Less pronounced phonon spectrum modifications have been found in MgH{sub 2} and NH{sub 3}BH{sub 3}, mainly concentrated in the low-energy acoustic region. Finally, no relevant effect has been observed for LiBH{sub 4} + Mg(BH{sub 4}){sub 2}.

  10. Characteristic length of phonon transport within periodic nanoporous thin films and two-dimensional materials

    Science.gov (United States)

    Hao, Qing; Xiao, Yue; Zhao, Hongbo

    2016-08-01

    In the past two decades, phonon transport within nanoporous thin films has attracted enormous attention for their potential applications in thermoelectrics and thermal insulation. Various computational studies have been carried out to explain the thermal conductivity reduction within these thin films. Considering classical phonon size effects, the lattice thermal conductivity can be predicted assuming diffusive pore-edge scattering of phonons and bulk phonon mean free paths. Following this, detailed phonon transport can be simulated for a given porous structure to find the lattice thermal conductivity [Hao et al., J. Appl. Phys. 106, 114321 (2009)]. However, such simulations are intrinsically complicated and cannot be used for the data analysis of general samples. In this work, the characteristic length Λ P o r e of periodic nanoporous thin films is extracted by comparing the predictions of phonon Monte Carlo simulations and the kinetic relationship using bulk phonon mean free paths modified by Λ P o r e . Under strong ballistic phonon transport, Λ P o r e is also extracted by the Monte Carlo ray-tracing method for graphene with periodic nanopores. The presented model can be widely used to analyze the measured thermal conductivities of such nanoporous structures.

  11. Energetics and dynamics of H$_2$ adsorbed in a nanoporous material at low temperature

    OpenAIRE

    Kong, Lingzhu; Román-Pérez, Guillermo; Soler, José M.; Langreth, David C.

    2009-01-01

    Molecular hydrogen adsorption in a nanoporous metal organic framework structure (MOF-74) was studied via van der Waals density-functional calculations. The primary and secondary binding sites for H$_2$ were confirmed. The low-lying rotational and translational energy levels were calculated, based on the orientation and position dependent potential energy surface at the two binding sites. A consistent picture is obtained between the calculated rotational-translational transitions for different...

  12. Application of Hydrothermal and Non-Hydrothermal TiO2 Nanoporous Materials as New Adsorbents for Removal of Heavy Metal Ions from Aqueous System

    Directory of Open Access Journals (Sweden)

    Mansoor Anbia

    2016-06-01

    Full Text Available Hydrothermal and non-hydrothermal spherical TiO2 nanoporous with crystalline framework were prepared by sol-gel method. The Crystalline structures, morphologies and surface texturing of materials were determined by X-ray diffraction (XRD, scanning electron microscopy (SEM and N2 adsorption-desorption isotherms. The Hydrothermal spherical TiO2 nanoporous was found to have a narrow and strong pore size distribution peaks with average of 37.8 Å and pore volume of 0.41 cm3/g and the (Brunauer–Emmett–TellerBET specific surface area of 365 m2/g. Hydrothermal and non-hydrothermal spherical TiO2 nanoporous have been used as adsorbent to study of the adsorption behavior of Pb(II, Co(II and Ni(II ions from aqueous system in a batch system. Effect of equilibrium time on adsorption Pb(II, Co(II and Ni(II ions on these adsorbent was studied The results show that the shaking time 0.5 to 10h has no serious effect on the percentage of ions removal, and the adsorption is fast in all cases. The maximum uptake capacities of Hydrothermal and non-hydrothermal spherical TiO2 nanoporous was calculated. Both hydrothermal and non-hydrothermal TiO2 nanoporous materials were found to have very good potential as new adsorbents in removal of these ions. In batch systems the maximum uptake capacities of Pb(II, Ni(II and Co(II on the hydrothermal and non-hydrothermal TiO2 nanoporous materials was Co(II > Pb(II > Ni(II and Co(II > Ni(II > Pb(II, respectively.

  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. SWOT analysis of Banff: strengths, weaknesses, opportunities and threats of the international Banff consensus process and classification system for renal allograft pathology.

    Science.gov (United States)

    Mengel, M; Sis, B; Halloran, P F

    2007-10-01

    The Banff process defined the diagnostic histologic lesions for renal allograft rejection and created a standardized classification system where none had existed. By correcting this deficit the process had universal impact on clinical practice and clinical and basic research. All trials of new drugs since the early 1990s benefited, because the Banff classification of lesions permitted the end point of biopsy-proven rejection. The Banff process has strengths, weaknesses, opportunities and threats (SWOT). The strength is its self-organizing group structure to create consensus. Consensus does not mean correctness: defining consensus is essential if a widely held view is to be proved wrong. The weaknesses of the Banff process are the absence of an independent external standard to test the classification; and its almost exclusive reliance on histopathology, which has inherent limitations in intra- and interobserver reproducibility, particularly at the interface between borderline and rejection, is exactly where clinicians demand precision. The opportunity lies in the new technology such as transcriptomics, which can form an external standard and can be incorporated into a new classification combining the elegance of histopathology and the objectivity of transcriptomics. The threat is the degree to which the renal transplant community will participate in and support this process.

  15. Nano-porous Material with Spherical or Gyroid Cavities Created by Quantitative Etching of Polydimethylsiloxane in Polystyrene-Polydimethylsiloxane Block Copolymers

    DEFF Research Database (Denmark)

    Ndoni, Sokol; Vigild, Martin Etchells; Berg, Rolf H.

    2003-01-01

    A new method for quantitative etching of the poly(dimethylsiloxane) block in polystyrene-poly(dimethylsiloxane) (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride renders a nanoporous material (NPM) with the remaining glassy PS maintaining...

  16. The role of synchrotron radiation in examining the self-assembly of crystalline nanoporous framework materials: from zeolites and aluminophosphates to metal organic hybrids

    NARCIS (Netherlands)

    O'Brien, M.G.; Beale, A.M.; Weckhuysen, B.M.

    2013-01-01

    This tutorial review describes the role of synchrotron-based techniques in the study of the formation of Crystalline Nanoporous Framework Materials (CNFMs), such as zeolites, aluminophosphates (AlPOs) and metal organic frameworks (MOFs). Initially, a general formation process for CNFMs is described

  17. Synthesis and Characterization of Nanoporous Carbon Materials; The Effect of Surfactant Concentrations and Salts

    Directory of Open Access Journals (Sweden)

    Shokoofeh Geranmayeh

    2011-01-01

    Full Text Available Nanoporous carbon framework was synthesized using phenol and formaldehyde as carbon precursors and triblock copolymer (pluronic F127 as soft template via evaporation induced self-assembly. Hexagonal mesoporous carbon with specific surface area of 350 m2/g through optimizing the situation was obtained. The effects of different surfactant/phenol molar ratio and presence of salts on specific surface area, pore size and pore volume for all the prepared samples were studied by means of the Brunauer-Emmett-Teller (BET formalism, powder X-ray diffraction technique and FT-IR spectroscopy.

  18. New polyimide-polyoxometalate nanocomposite materials with nanoporous structure and ultra-low dielectric constant, formed in supercritical carbon dioxide

    Science.gov (United States)

    Keshtov, Mukhamed; Said-Galiev, Ernest; Kochurov, Vitaliy; Khokhlov, Alexei

    2012-07-01

    Vinyltrimethoxysilane interaction with K8(SiW11O39) obtained polyoxometalate (Bu4N)4[SiW11O39{(CH2 = CH-Si)2O}](SiW11-CH = CH2). Synthesized two new fluorinated aromatic polyimide in two stages with a dielectric constant (k) in the range 2.70-2.75. On the basis of poly(amic acids) and a mixture of thermal imidization polyoxometalate obtained polyimide/polyoxometalate composite film. It was found that with increasing polyoxometalate in a mixture of 0 to 20 wt% the dielectric constant decreases from 2,75 to 1,70. Nanoporous materials with ultra-low dielectric constant in the range 1.31-1.64 in combination with high thermal (T10% = 536-570°C in N2) and mechanical characteristics using supercritical carbon dioxide have been developed on the basis of the obtained polyimide/polyoxometalate composite films.

  19. Nanopores formed by DNA origami: a review.

    Science.gov (United States)

    Bell, Nicholas A W; Keyser, Ulrich F

    2014-10-01

    Nanopores have emerged over the past two decades to become an important technique in single molecule experimental physics and biomolecule sensing. Recently DNA nanotechnology, in particular DNA origami, has been used for the formation of nanopores in insulating materials. DNA origami is a very attractive technique for the formation of nanopores since it enables the construction of 3D shapes with precise control over geometry and surface functionality. DNA origami has been applied to nanopore research by forming hybrid architectures with solid state nanopores and by direct insertion into lipid bilayers. This review discusses recent experimental work in this area and provides an outlook for future avenues and challenges.

  20. Precision Photothermal Annealing of Nanoporous Gold Thin Films for the Microfabrication of a Single-chip Material Libraries

    Energy Technology Data Exchange (ETDEWEB)

    Harris, C. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shen, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rubenchik, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Demos, S. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Matthews, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-06-30

    Single-chip material libraries of thin films of nanostructured materials are a promising approach for high throughput studies of structure-property relationship in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material of specific interest in both these fields. One attractive property of np-Au is its self-similar coarsening behavior by thermally induced surface diffusion. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Laser micromachining offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In the present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and supporting substrate thermal conductivity on the local np-Au film temperatures during photothermal annealing and subsequently investigate the mechanisms by which the np-Au network is coarsening. Our simulations predict that continuous-wave mode laser irradiation on a silicon supporting substrate supports the widest range of morphologies that can be created through the photothermal annealing of thin film np-Au. Using this result we successfully fabricate a single-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in increased throughput material interaction studies.

  1. Energetics and Dynamics of H2 Adsorbed in a Nanoporous Material at Low Temperature

    Science.gov (United States)

    Kong, Lingzhu; Román-Pérez, Guillermo; Soler, José M.; Langreth, David C.

    2009-08-01

    Molecular hydrogen adsorption in a nanoporous metal-organic framework structure (MOF-74) is studied via van der Waals density-functional calculations. The primary and secondary binding sites for H2 are confirmed. The low-lying rotational and translational energy levels are calculated, based on the orientation and position dependent potential energy surface at the two binding sites. A consistent picture is obtained between the calculated rotational-translational transitions for different H2 loadings and those measured by inelastic neutron scattering exciting the singlet to triplet (para to ortho) transition in H2. The H2 binding energy after zero-point energy correction due to the rotational and translational motions is predicted to be ˜100meV in good agreement with the experimental value of ˜90meV.

  2. Synthesis of nanoporous materials using block copolymers and applications as battery separators

    Science.gov (United States)

    Wong, David; Mullin, Scott; Stone, Greg; Balsara, Nitash

    2010-03-01

    A method for synthesizing nanoporous battery separators using poly(styrene-b-ethylene-b-polystyrene) (SES) is presented. The polyethylene block serves as a structural component, while the polystyrene block promotes wetting of the electrolyte. The ionic conductivity of these systems swollen with 1M LiPF6/Ethylene Carbonate/Diethyl Carbonate (EC/DEC) electrolyte was measured by AC impedance. Other groups have shown that radiation induced grafting of gel polymer electrolytes can increase the conductivity of a porous PE/LiPF6/EC/DEC system by as much as an order of magnitude. Data showing the ionic conductivity as a function of void fraction of the separator are presented.

  3. One pot aqueous synthesis of nanoporous Au85Pt15 material with surface bound Pt islands: an efficient methanol tolerant ORR catalyst

    Science.gov (United States)

    Anandha Ganesh, P.; Jeyakumar, D.

    2014-10-01

    For the first time, we are reporting the synthesis of Au100-xPtx nanoporous materials in the size range of 7-10 nm through the galvanic replacement of Ag by Pt from Au100-xAg2x spherical nano-alloys (x = 20, 15, 10 and 5) in an aqueous medium. The galvanic replacement reaction follows the `Volmer-Weber' growth mode, resulting in the formation of surface bound platinum islands on a nanoporous gold surface. The high angle annular dark field image and low angle X-ray diffraction studies confirm the presence of nanoporous Au100-xPtx NPs. The electrochemical studies using the Au85Pt15/C catalyst show excellent methanol tolerance behaviour and better performance towards oxygen reduction reaction (ORR) in terms of high mass activity, mass-specific activity and figure of merit (FOM) when compared to HiSPEC Pt/C commercial catalyst. Preliminary studies on a full cell using nanoporous Au85Pt15/C (loading 1.0 mg cm-2) as the cathode material and Pt-Ru/C (loading: 0.5 mg cm-2) as the anode material performed better (38 mW cm-2) than the HiSPEC Pt/C cathode material (16 mW cm-2).For the first time, we are reporting the synthesis of Au100-xPtx nanoporous materials in the size range of 7-10 nm through the galvanic replacement of Ag by Pt from Au100-xAg2x spherical nano-alloys (x = 20, 15, 10 and 5) in an aqueous medium. The galvanic replacement reaction follows the `Volmer-Weber' growth mode, resulting in the formation of surface bound platinum islands on a nanoporous gold surface. The high angle annular dark field image and low angle X-ray diffraction studies confirm the presence of nanoporous Au100-xPtx NPs. The electrochemical studies using the Au85Pt15/C catalyst show excellent methanol tolerance behaviour and better performance towards oxygen reduction reaction (ORR) in terms of high mass activity, mass-specific activity and figure of merit (FOM) when compared to HiSPEC Pt/C commercial catalyst. Preliminary studies on a full cell using nanoporous Au85Pt15/C (loading 1.0 mg

  4. Electrochemical Biosensor Based on Nanoporous Au/CoO Core-Shell Material with Synergistic Catalysis.

    Science.gov (United States)

    Zhang, Chao; Huang, Bin; Qian, Lihua; Yuan, Songliu; Wang, Shuai; Chen, Rong

    2016-01-04

    An ultrathin CoO layer is deposited on the skeleton surfaces of a nanoporous gold (NPG) film by using atomic layer deposition, creating a flexible electrode. Detailed characterization demonstrates the superior performance of the flexible NPG/CoO hybrids for electrochemical catalysis. The NPG/CoO hybrid not only achieves high catalytic activity for glucose oxidation and H2O2 reduction, but also exhibits a linear dependence of the electrical signal on the concentration of glucose and H2O2 molecules in the electrolyte. Meanwhile, the sensitivity for H2O2 reduction can be as high as 62.5 μA mm(-1)  cm(-2) with linear dependence on the concentration in the range of 0.1-92.9 mm. The high sensitivity is proposed to result from the synergistic effect of Au and CoO at the interfaces, and the high conductivity of the gold skeleton with a large surface area. The superior electrochemical performance of this hybrid electrode is promising for future potential applications in various transitional-metal-oxide-based electrochemical electrodes.

  5. Renal graft survival according to Banff 2013 classification in indication biopsies

    Directory of Open Access Journals (Sweden)

    Carlos Arias-Cabrales

    2016-11-01

    Conclusions: The Banff 2013 classification facilitates a histological diagnosis in 95% of indication biopsies. While diagnostic category 6 is the most common, a change in the predominant histopathology was observed according to time elapsed since transplantation. Antibody-mediated changes are associated with worse graft survival.

  6. Density functional theory based tight binding study on theoretical prediction of low-density nanoporous phases ZnO semiconductor materials

    Science.gov (United States)

    Tuoc, Vu Ngoc; Doan Huan, Tran; Viet Minh, Nguyen; Thi Thao, Nguyen

    2016-06-01

    Polymorphs or phases - different inorganic solids structures of the same composition usually have widely differing properties and applications, thereby synthesizing or predicting new classes of polymorphs for a certain compound is of great significance and has been gaining considerable interest. Herein, we perform a density functional theory based tight binding (DFTB) study on theoretical prediction of several new phases series of II-VI semiconductor material ZnO nanoporous phases from their bottom-up building blocks. Among these, three phases are reported for the first time, which could greatly expand the family of II- VI compound nanoporous phases. We also show that all these generally can be categorized similarly to the aluminosilicate zeolites inorganic open-framework materials. The hollow cage structure of the corresponding building block ZnkOk (k= 9, 12, 16) is well preserved in all of them, which leads to their low-density nanoporous and high flexibility. Additionally the electronic wide-energy gap of the individual ZnkOk is also retained. Our study reveals that they are all semiconductor materials with a large band gap. Further, this study is likely to be the common for II-VI semiconductor compounds and will be helpful for extending their range of properties and applications.

  7. Facile synthesis of sewage sludge-derived in-situ multi-doped nanoporous carbon material for electrocatalytic oxygen reduction

    Science.gov (United States)

    Yuan, Shi-Jie; Dai, Xiao-Hu

    2016-06-01

    Developing efficient, low-cost, and stable carbon-based catalysts for oxygen reduction reaction (ORR) to replace the expensive platinum-based electrocatalysts remains a major challenge that hamper the practical application of fuel cells. Here, we report that N, Fe, and S co-doped nanoporous carbon material, derived via a facile one-step pyrolysis of sewage sludge, the major byproduct of wastewater treatment, can serve as an effective electrocatalyst for ORR. Except for the comparable catalytic activity with commercial 20% Pt/C via a nearly four-electron transfer pathway in both alkaline and acid medium, the as-synthesized co-doped electrocatalyst also exhibits excellent methanol crossover resistance and outstanding long-term operation stability. The organic compounds in sewage sludge act as the carbon source and the in-situ N and S dopant in the fabrication, while the inorganic compounds serve as the in-built template and the in-situ Fe dopant. Our protocol demonstrates a new approach in the economic and eco-friendly benign reuse of sewage sludge, and also provides a straightforward route for synthesizing excellent carbon-based electrocatalysts as promising candidates for ORR directly from a type of waste/pollution.

  8. 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.

  9. Non-linear model of impurity diffusion in nanoporous materials upon ultrasonic treatment

    Directory of Open Access Journals (Sweden)

    R.M. Peleshchak

    2014-06-01

    Full Text Available Non-linear theory of diffusion of impurities in porous materials upon ultrasonic treatment is described. It is shown that at a defined value of deformation amplitude, an average concentration of vacancies and temperature as a result of the effect of ultrasound possibly leads to the formation of nanoclusters of vacancies and to their periodic educations in porous materials. It is shown that at a temperature smaller than some critical value, a significant growth of a diffusion coefficient is observed in porous materials.

  10. Mechanism of low thermal conductivity of xonotlite-silica aerogel nanoporous super insulation material

    Institute of Scientific and Technical Information of China (English)

    Hailong Yang; Wen Ni; Deping Chen; Guoqiang Xu; Tao Liang; Li Xu

    2008-01-01

    In an effort to incorporate the low thermal conductivity of the silica aerogel and the superior structure strength of the xonotlite, a composite material of these two was produced. It was synthesized under vacuum condition and dried by supercritical drying technique. The thermal conductivity of the new material, which is at 298 K with the gas pressure ranging from 1.01×105 to 1× 10-2 Pa, was measured using the transient hot-strip method. The mechanism of the low thermal conductivity was studied. The re-suits indicate that the low thermal conductivity mainly results from the significant decrease of gaseous thermal conductivity of the new material due to the restriction of the motion of gas molecules in its fine structures. The formation of the fine structures is be-cause the new material takes the pore structure of the silica aerogel which consists of mainly nanometer-sized pores.

  11. Recent advances in hydrogen storage technologies based on nanoporous carbon materials

    National Research Council Canada - National Science Library

    Seung Jae Yang Haesol Jung Taehoon Kim Chong Rae Park

    2012-01-01

    ... by-products.Prior to realizing a hydrogen economy,however,viable hydrogen storage materials must be developed.Physical adsorption in porous solids provides an opportunity for hydrogen storage under low-stringency...

  12. 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...

  13. Threading DNA through nanopores for biosensing applications

    Science.gov (United States)

    Fyta, Maria

    2015-07-01

    This review outlines the recent achievements in the field of nanopore research. Nanopores are typically used in single-molecule experiments and are believed to have a high potential to realize an ultra-fast and very cheap genome sequencer. Here, the various types of nanopore materials, ranging from biological to 2D nanopores are discussed together with their advantages and disadvantages. These nanopores can utilize different protocols to read out the DNA nucleobases. Although, the first nanopore devices have reached the market, many still have issues which do not allow a full realization of a nanopore sequencer able to sequence the human genome in about a day. Ways to control the DNA, its dynamics and speed as the biomolecule translocates the nanopore in order to increase the signal-to-noise ratio in the reading-out process are examined in this review. Finally, the advantages, as well as the drawbacks in distinguishing the DNA nucleotides, i.e., the genetic information, are presented in view of their importance in the field of nanopore sequencing.

  14. Synthesis of Si/SiO2/ZnO nanoporous materials using chemical and electrochemical deposition techniques

    Science.gov (United States)

    Dauletbekova, A. K.; Alzhanova, A. Ye.; Akilbekov, A. T.; Mashentseva, A. A.; Zdorovets, M. V.; Balabekov, K. N.

    2016-09-01

    The work represents the results of forming Zn-based nanoprecipitates in nanoporous amorphous silicon dioxide on silicon substrate by the template synthesis method. SEM and AFM images of the surface after chemical and electrochemical deposition of zinc were obtained. The analysis of photoluminescence of the precipitated samples resulted in the assumption of formation of nanoclusters of zinc oxide.

  15. Chemical Hieroglyphs: Abstract Depiction of Complex Void Space Topology of Nanoporous Materials

    Energy Technology Data Exchange (ETDEWEB)

    Theisen, Kevin; Smit, Berend; Haranczyk, Maciej

    2010-04-26

    In general, most porous materials are so complex that structural information cannot be easily observed with 3D visualization tools. To address this problem, we have developed a special abstract 2D representation to depict all important topological features and geometrical parameters. Our approach involves reducing these structures based on symmetry and perceived building blocks to a compressed, graph representation that allows for quick structure analysis, classification, and comparison.

  16. Chemical hieroglyphs: abstract depiction of complex void space topology of nanoporous materials.

    Science.gov (United States)

    Theisen, Kevin; Smit, Berend; Haranczyk, Maciej

    2010-04-26

    In general, most porous materials are so complex that structural information cannot be easily observed with 3D visualization tools. To address this problem, we have developed a special abstract 2D representation to depict all important topological features and geometrical parameters. Our approach involves reducing these structures based on symmetry and perceived building blocks to a compressed, graph representation that allows for quick structure analysis, classification, and comparison.

  17. Computational investigation of noble gas adsorption and separation by nanoporous materials.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D. (Sandia National Laboratories, Livermore, CA); Sanders, Joseph C.; Greathouse, Jeffery A.

    2008-10-01

    Molecular simulations are used to assess the ability of metal-organic framework (MOF) materials to store and separate noble gases. Specifically, grand canonical Monte Carlo simulation techniques are used to predict noble gas adsorption isotherms at room temperature. Experimental trends of noble gas inflation curves of a Zn-based material (IRMOF-1) are matched by the simulation results. The simulations also predict that IRMOF-1 selectively adsorbs Xe atoms in Xe/Kr and Xe/Ar mixtures at total feed gas pressures of 1 bar (14.7 psia) and 10 bar (147 psia). Finally, simulations of a copper-based MOF (Cu-BTC) predict this material's ability to selectively adsorb Xe and Kr atoms when present in trace amounts in atmospheric air samples. These preliminary results suggest that Cu-BTC may be an ideal candidate for the pre-concentration of noble gases from air samples. Additional simulations and experiments are needed to determine the saturation limit of Cu-BTC for xenon, and whether any krypton atoms would remain in the Cu-BTC pores upon saturation.

  18. Hydrogen storing and electrical properties of hyperbranched polymers-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Rehim, Mona H., E-mail: monaabdelrehim@yahoo.com [Packing and Packaging Materials Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Ismail, Nahla; Badawy, Abd El-Rahman A.A. [Physical Chemistry Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Turky, Gamal [Microwave Physics and Dielectrics Department, National Research Center, Cairo (Egypt)

    2011-09-15

    Highlights: {center_dot} The hydrogen storage capacity of hyperbranched P-Urea, PAMAM and PAMAM and VO{sub x} is studied and electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. {center_dot} Electrical properties measurements for the samples showed complete insulating behavior at hydrogenation measuring temperature. {center_dot} These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. - Abstract: Hydrogen storage and electrical properties of different hyperbranched polymer systems beside a nanocomposite are studied. The polymers examined are aliphatic hyperbranched poly urea (P-Urea), polyamide amine (PAMAM) and polyamide amine/vanadium oxide (PAMAM/VO{sub x}) nanocomposite. At 80 K and up to 20 bar hydrogen pressure, the hydrogen storage capacity of hyperbranched P-Urea reached 1.6 wt%, 0.9 wt% in case of PAMAM and 0.6 wt% for VO{sub x}. The hydrogen storage capacity significantly enhanced when PAMAM and VO{sub x} form a nanocomposite and increased up to 2 wt%. At 298 K and up to 20 bar, all the samples did not show measurable hydrogen uptake. Electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage.

  19. Microscopic Observation of Kinetic Molecular Sieving of Hydrogen Isotopes in a Nanoporous Material

    Science.gov (United States)

    Nguyen, T. X.; Jobic, H.; Bhatia, S. K.

    2010-08-01

    We report quasielastic neutron scattering studies of H2-D2 diffusion in a carbon molecular sieve, demonstrating remarkable quantum effects, with the heavier isotope diffusing faster below 100 K, confirming our recent predictions. Our transition state theory and molecular dynamics calculations show that while it is critical for this effect to have narrow windows of size comparable to the de Broglie wavelength, high flux requires that the energy barrier be reduced through small cages. Such materials will enable novel processes for kinetic molecular sieving of hydrogen isotopes.

  20. Photoprocesses of coordination compounds and dyes in solution and nanoporous materials: Evolution from milliseconds to femtoseconds

    Indian Academy of Sciences (India)

    P Natarajan; K Duraimurugan; K Senthil Kumar

    2011-09-01

    The photoredox reactions of cobalt(III), nickel(II) complexes and organic dyes are reviewed with particular emphasis on using flash photolysis methods to identify the transients in the time scale from milliseconds to subpicoseconds. The excitation flash radiation initially was limited to flash lamps with a time resolution to study the decay of the excited states and the fast reactions of photo produced transients in milliseconds and microseconds. Some of the photolysis reactions investigated provide details in real time including the thermal reactions of molecular oxygen with cobalt(II) amine systems and the cobalt (III) alkyl complex formation on photolysis of cobalt(III) aminoacid complexes. Photoredox reactions of thiazine and safranine dyes are investigated using time resolved absorption and emission techniques in solution and on encapsulation in micro and mesoporous host materials. Picosecond and femtosecond diffuse reflectance fluorescence investigations in the porous solid host materials show intramolecular proton transfer reactions of the dyes and deprotonation of the dyes in the excited states. Photosensitization of nanoparticles of semiconductors, anatase TiO2 and ZnO by the excited states of dyes in meso and microporous silicate hosts is investigated using pico and femtosecond fluorescence and transient absorptions techniques and the results are reviewed.

  1. Multiphase imaging of gas flow in a nanoporous material usingremote detection NMR

    Energy Technology Data Exchange (ETDEWEB)

    Harel, Elad; Granwehr, Josef; Seeley, Juliette A.; Pines, Alex

    2005-10-03

    Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering, or as reactors. We report a model study on silica aerogel using a recently introduced time-of-flight (TOF) magnetic resonance imaging technique to characterize the flow field and elucidate the effects of heterogeneities in the pore structure on gas flow and dispersion with Xe-129 as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides new insights into the dynamics of flow in porous media where multiple phases or chemical species may be present.

  2. Nanoporous Materials Can Tune the Critical Point of a Pure Substance.

    Science.gov (United States)

    Braun, Efrem; Chen, Joseph J; Schnell, Sondre K; Lin, Li-Chiang; Reimer, Jeffrey A; Smit, Berend

    2015-11-23

    Molecular simulations and NMR relaxometry experiments demonstrate that pure benzene or xylene confined in isoreticular metal-organic frameworks (IRMOFs) exhibit true vapor-liquid phase equilibria where the effective critical point may be reduced by tuning the structure of the MOF. Our results are consistent with vapor and liquid phases extending over many MOF unit cells. These results are counterintuitive since the MOF pore diameters are approximately the same length scale as the adsorbate molecules. As applications of these materials in catalysis, separations, and gas storage rely on the ability to tune the properties of adsorbed molecules, we anticipate that the ability to systematically control the critical point, thereby preparing spatially inhomogeneous local adsorbate densities, could add a new design tool for MOF applications.

  3. Nanoporous Materials Can Tune the Critical Point of a Pure Substance

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Efrem; Chen, Joseph J.; Schnell, Sondre K.; Lin, Li-Chiang; Reimer, Jeffrey A.; Smit, Berend

    2015-09-30

    Molecular simulations and NMR relaxometry experiments demonstrate that pure benzene or xylene confined in isoreticular metal–organic frameworks (IRMOFs) exhibit true vapor–liquid phase equilibria where the effective critical point may be reduced by tuning the structure of the MOF. Our results are consistent with vapor and liquid phases extending over many MOF unit cells. These results are counterintuitive since the MOF pore diameters are approximately the same length scale as the adsorbate molecules. As applications of these materials in catalysis, separations, and gas storage rely on the ability to tune the properties of adsorbed molecules, we anticipate that the ability to systematically control the critical point, thereby preparing spatially inhomogeneous local adsorbate densities, could add a new design tool for MOF applications.

  4. Charge carrier trapping into mobile, ionic defects in nanoporous ultra-low-k dielectric materials

    Science.gov (United States)

    Plawsky, Joel; Borja, Juan; Lu, Toh-Ming; Gill, William

    2014-03-01

    Reliability and robustness of low-k materials for advanced interconnects has become a major challenge for the continuous down-scaling of silicon semiconductor devices. Metal catalyzed time dependent breakdown (TDDB) is a major force preventing the integration of sub-32nm process technology nodes. We investigate how ionic species can become trapping centers (mobile defects) for charge carriers. A mechanism for describing and quantifying the trapping of charge carriers into mobile ions under bias and temperature stress is presented and experimentally investigated. The dynamics of trapping into ionic centers are severely impacted by temperature and species mass transport. After extended bias and temperature stress, the magnitude of charge trapping into ionic centers decreases asymptotically. Various processes such as the reduction of ionic species, moisture outgassing, and the inhibition of ionic drift via the distortion of local fields were investigated as possible cause for the reduction in charge trapping. Simulations suggest that built-in fields reduce the effect of an externally applied field in directing ionic drift, which can lead to the inhibition of the trapping mechanism. In addition, conduction mechanisms are investigated for reactive and inert electrodes. Seimconductor Research Corporation.

  5. 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.

  6. Graphene nanopore devices for DNA sensing.

    Science.gov (United States)

    Merchant, Chris A; Drndić, Marija

    2012-01-01

    We describe here a method for detecting the translocation of individual DNA molecules through nanopores created in graphene membranes. The devices consist of 1-5-nm thick graphene membranes with electron-beam sculpted nanopores from 5 to 10 nm in diameter. Due to the thin nature of the graphene membranes, and the reduced electrical resistance, we observe larger blocked currents than for traditional solid-state nanopores. We also show how ionic current noise levels can be reduced with the atomic-layer deposition of a few nanometers of titanium dioxide over the graphene surface. Unlike traditional solid-state nanopore materials that are insulating, graphene is an excellent electrical conductor, and its use opens the door to a new future class of nanopore devices in which electronic sensing and control is performed directly at the pore.

  7. Renal graft survival according to Banff 2013 classification in indication biopsies.

    Science.gov (United States)

    Arias-Cabrales, Carlos; Redondo-Pachón, Dolores; Pérez-Sáez, María José; Gimeno, Javier; Sánchez-Güerri, Ignacio; Bermejo, Sheila; Sierra, Adriana; Burballa, Carla; Mir, Marisa; Crespo, Marta; Pascual, Julio

    The impact of acute rejection in kidney graft survival is well known, but the prognosis of other diagnoses is uncertain. We evaluated the frequency and impact on graft survival of different diagnostic categories according to the Banff 2013 classification in a cohort of renal transplant recipients. Retrospective study of 495 renal biopsies by indication in 322 patients from 1990-2014. Two independent observers reviewed the histological reports, reclassifying according to the Banff 2013 classification. Of 495 biopsies, 28 (5.7%) were not diagnostic. Of the remaining 467, 10.3% were «normal» (category 1), 19.6% antibody-mediated changes (category 2), 5.9% «borderline» changes (category 3), 8.7% T-cell-mediated rejection (category 4), 23.4% interstitial fibrosis/tubular atrophy (IFTA) (category 5) and 26.5% with other diagnoses (category 6). As time after transplantation increases, diagnoses of categories 1, 3 and 4 decrease, while categories 5 and 2 increase. Worse graft survival with category 2 diagnosis was observed (45% at 7.5 years, HR 4.29 graft loss [95% CI, 2.39-7.73]; P≤.001, compared to category 1). Grafts with «unfavourable histology» (chronic antibody-mediated rejection, moderate-severe IFTA) presented worse survival that grafts with «favourable histology» (normal, acute tubular necrosis, mild IFTA). The Banff 2013 classification facilitates a histological diagnosis in 95% of indication biopsies. While diagnostic category 6 is the most common, a change in the predominant histopathology was observed according to time elapsed since transplantation. Antibody-mediated changes are associated with worse graft survival. Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

  8. Demographic connectivity for ursid populations at wildlife crossing structures in Banff National Park.

    Science.gov (United States)

    Sawaya, Michael A; Clevenger, Anthony P; Kalinowski, Steven T

    2013-08-01

    Wildlife crossing structures are one solution to mitigating the fragmentation of wildlife populations caused by roads, but their effectiveness in providing connectivity has only been superficially evaluated. Hundreds of grizzly (Ursus arctos) and black bear (Ursus americanus) passages through under and overpasses have been recorded in Banff National Park, Alberta, Canada. However, the ability of crossing structures to allow individual and population-level movements across road networks remains unknown. In April 2006, we initiated a 3-year investigation into whether crossing structures provide demographic connectivity for grizzly and black bears in Banff National Park. We collected hair with multiple noninvasive methods to obtain genetic samples from grizzly and black bears around the Bow Valley. Our objectives were to determine the number of male and female grizzly and black bears that use crossing structures; examine spatial and temporal patterns of crossings; and estimate the proportions of grizzly and black bear populations in the Bow Valley that use crossing structures. Fifteen grizzly (7 female, 8 male) and 17 black bears (8 female, 9 male) used wildlife crossing structures. The number of individuals detected at wildlife crossing structures was highly correlated with the number of passages in space and time. Grizzly bears used open crossing structures (e.g., overpasses) more often than constricted crossings (e.g., culverts). Peak use of crossing structures for both bear species occurred in July, when high rates of foraging activity coincide with mating season. We compared the number of bears that used crossings with estimates of population abundance from a related study and determined that substantial percentages of grizzly (15.0% in 2006, 19.8% in 2008) and black bear (17.6% in 2006, 11.0% in 2008) populations used crossing structures. On the basis of our results, we concluded wildlife crossing structures provide demographic connectivity for bear populations

  9. Assessing Potential Habitat and Carrying Capacity for Reintroduction of Plains Bison (Bison bison bison in Banff National Park.

    Directory of Open Access Journals (Sweden)

    Robin Steenweg

    Full Text Available Interest in bison (Bison bison, B. bonasus conservation and restoration continues to grow globally. In Canada, plains bison (B. b. bison are threatened, occupying less than 0.5% of their former range. The largest threat to their recovery is the lack of habitat in which they are considered compatible with current land uses. Fences and direct management make range expansion by most bison impossible. Reintroduction of bison into previously occupied areas that remain suitable, therefore, is critical for bison recovery in North America. Banff National Park is recognized as historical range of plains bison and has been identified as a potential site for reintroduction of a wild population. To evaluate habitat quality and assess if there is sufficient habitat for a breeding population, we developed a Habitat Suitability Index (HSI model for the proposed reintroduction and surrounding areas in Banff National Park (Banff. We then synthesize previous studies on habitat relationships, forage availability, bison energetics and snowfall scenarios to estimate nutritional carrying capacity. Considering constraints on nutritional carrying capacity, the most realistic scenario that we evaluated resulted in an estimated maximum bison density of 0.48 bison/km2. This corresponds to sufficient habitat to support at least 600 to 1000 plains bison, which could be one of the largest 10 plains bison populations in North America. Within Banff, there is spatial variation in predicted bison habitat suitability and population size that suggests one potential reintroduction site as the most likely to be successful from a habitat perspective. The successful reintroduction of bison into Banff would represent a significant global step towards conserving this iconic species, and our approach provides a useful template for evaluating potential habitat for other endangered species reintroductions into their former range.

  10. Assessing Potential Habitat and Carrying Capacity for Reintroduction of Plains Bison (Bison bison bison) in Banff National Park.

    Science.gov (United States)

    Steenweg, Robin; Hebblewhite, Mark; Gummer, David; Low, Brian; Hunt, Bill

    2016-01-01

    Interest in bison (Bison bison, B. bonasus) conservation and restoration continues to grow globally. In Canada, plains bison (B. b. bison) are threatened, occupying less than 0.5% of their former range. The largest threat to their recovery is the lack of habitat in which they are considered compatible with current land uses. Fences and direct management make range expansion by most bison impossible. Reintroduction of bison into previously occupied areas that remain suitable, therefore, is critical for bison recovery in North America. Banff National Park is recognized as historical range of plains bison and has been identified as a potential site for reintroduction of a wild population. To evaluate habitat quality and assess if there is sufficient habitat for a breeding population, we developed a Habitat Suitability Index (HSI) model for the proposed reintroduction and surrounding areas in Banff National Park (Banff). We then synthesize previous studies on habitat relationships, forage availability, bison energetics and snowfall scenarios to estimate nutritional carrying capacity. Considering constraints on nutritional carrying capacity, the most realistic scenario that we evaluated resulted in an estimated maximum bison density of 0.48 bison/km2. This corresponds to sufficient habitat to support at least 600 to 1000 plains bison, which could be one of the largest 10 plains bison populations in North America. Within Banff, there is spatial variation in predicted bison habitat suitability and population size that suggests one potential reintroduction site as the most likely to be successful from a habitat perspective. The successful reintroduction of bison into Banff would represent a significant global step towards conserving this iconic species, and our approach provides a useful template for evaluating potential habitat for other endangered species reintroductions into their former range.

  11. 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

  12. 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.

  13. 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.

  14. Immobilization of Enzymes in Nanoporous Host Materials: A Nanobiotechnological Approach to Decontamination and Demilitarization of Chemical and Biological Warfare Agents

    Science.gov (United States)

    2007-11-02

    Type IV with H2 hysteresis loop, typical of mesoporous materials. The incorporation of the methyl group into the silica matrix (OPAA-HF series samples...compared to that of the immobilized enzymes in TMOS-derived materials. The non-surfactant template pathway58-59 to the mesoporous silica materials...biocatalyst OPAA into mesoporous silica host materials of various compositions. OPAA was chosen owing to its ability to catalyze the hydrolysis of highly

  15. Managing fire for woodland caribou in Jasper and Banff National Parks

    Directory of Open Access Journals (Sweden)

    Landon Shepherd

    2007-04-01

    Full Text Available Woodland caribou (Rangifer tarandus caribou populations in Jasper (JNP and Banff National Parks (BNP have declined since the 1970s, coincident with reduced fire activity in both parks, relative to historic levels. Some researchers have suggested that long periods without fire may cause habitat deterioration for woodland caribou, primarily by reducing available lichen forage. We examined winter habitat selection by woodland caribou at coarse and fine scales based on GPS-derived telemetry data and used models that included stand origin (decade, topography, and several stand structure variables that are related to time since fire, to explore relationships among caribou, lichen, and fire history. Based on the relationships illustrated by the models, we assessed how fire management could be applied to caribou conservation in JNP and BNP. At a coarse scale, caribou selected old forest (> 75 years in landscapes that have likely experienced less frequent wildfire. While the abundance of Cladonia spp. influenced caribou use at fine scales, a preference for areas with older trees within stands was also significant. We conclude that short-term habitat protection for woodland caribou in JNP and BNP likely requires fire exclusion from caribou range.

  16. Genetic connectivity for two bear species at wildlife crossing structures in Banff National Park.

    Science.gov (United States)

    Sawaya, Michael A; Kalinowski, Steven T; Clevenger, Anthony P

    2014-04-01

    Roads can fragment and isolate wildlife populations, which will eventually decrease genetic diversity within populations. Wildlife crossing structures may counteract these impacts, but most crossings are relatively new, and there is little evidence that they facilitate gene flow. We conducted a three-year research project in Banff National Park, Alberta, to evaluate the effectiveness of wildlife crossings to provide genetic connectivity. Our main objective was to determine how the Trans-Canada Highway and crossing structures along it affect gene flow in grizzly (Ursus arctos) and black bears (Ursus americanus). We compared genetic data generated from wildlife crossings with data collected from greater bear populations. We detected a genetic discontinuity at the highway in grizzly bears but not in black bears. We assigned grizzly bears that used crossings to populations north and south of the highway, providing evidence of bidirectional gene flow and genetic admixture. Parentage tests showed that 47% of black bears and 27% of grizzly bears that used crossings successfully bred, including multiple males and females of both species. Differentiating between dispersal and gene flow is difficult, but we documented gene flow by showing migration, reproduction and genetic admixture. We conclude that wildlife crossings allow sufficient gene flow to prevent genetic isolation.

  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. Monolithic aerogels with nanoporous crystalline phases

    Science.gov (United States)

    Daniel, Christophe; Guerra, Gaetano

    2015-05-01

    High porosity monolithic aerogels with nanoporous crystalline phases can be obtained from syndiotactic polystyrene and poly(2,6-dimethyl-1,4-phenylene)oxide thermoreversible gels by removing the solvent with supercritical CO2. The presence of crystalline nanopores in the aerogels based on these polymers allows a high uptake associated with a high selectivity of volatile organic compounds from vapor phase or aqueous solutions even at very low activities. The sorption and the fast kinetics make these materials particularly suitable as sorption medium to remove traces of pollutants from water and moist air.

  19. Nanoporous Gold: Fabrication, Characterization, and Applications

    Directory of Open Access Journals (Sweden)

    Michael L. Reed

    2009-12-01

    Full Text Available Nanoporous gold (np-Au has intriguing material properties that offer potential benefits for many applications due to its high specific surface area, well-characterized thiol-gold surface chemistry, high electrical conductivity, and reduced stiffness. The research on np-Au has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here, we provide a review of the recent advances in np-Au research, with special emphasis on microfabrication and characterization techniques. We conclude the paper with a brief outline of challenges to overcome in the study of nanoporous metals.

  20. Method for making nanoporous hydrophobic coatings

    Science.gov (United States)

    Fan, Hongyou; Sun, Zaicheng

    2013-04-23

    A simple coating method is used to form nanoporous hydrophobic films that can be used as optical coatings. The method uses evaporation-induced self-assembly of materials. The coating method starts with a homogeneous solution comprising a hydrophobic polymer and a surfactant polymer in a selective solvent. The solution is coated onto a substrate. The surfactant polymer forms micelles with the hydrophobic polymer residing in the particle core when the coating is dried. The surfactant polymer can be dissolved and selectively removed from the separated phases by washing with a polar solvent to form the nanoporous hydrophobic film.

  1. Structure-property relations of gold and graphene nanoporous actuators

    NARCIS (Netherlands)

    Saane, Siva Shankar Reddy

    2015-01-01

    Electrochemical nanoporous actuators have low weight, large specific surface areas and low voltage operating capabilities, making them attractive for application in small-scale electromechanical devices. The actuation strain of these materials at the macroscopic scale is a manifestation of

  2. 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.

  3. Nanoporous silicon oxide memory.

    Science.gov (United States)

    Wang, Gunuk; Yang, Yang; Lee, Jae-Hwang; Abramova, Vera; Fei, Huilong; Ruan, Gedeng; Thomas, Edwin L; Tour, James M

    2014-08-13

    Oxide-based two-terminal resistive random access memory (RRAM) is considered one of the most promising candidates for next-generation nonvolatile memory. We introduce here a new RRAM memory structure employing a nanoporous (NP) silicon oxide (SiOx) material which enables unipolar switching through its internal vertical nanogap. Through the control of the stochastic filament formation at low voltage, the NP SiOx memory exhibited an extremely low electroforming voltage (∼ 1.6 V) and outstanding performance metrics. These include multibit storage ability (up to 9-bits), a high ON-OFF ratio (up to 10(7) A), a long high-temperature lifetime (≥ 10(4) s at 100 °C), excellent cycling endurance (≥ 10(5)), sub-50 ns switching speeds, and low power consumption (∼ 6 × 10(-5) W/bit). Also provided is the room temperature processability for versatile fabrication without any compliance current being needed during electroforming or switching operations. Taken together, these metrics in NP SiOx RRAM provide a route toward easily accessed nonvolatile memory applications.

  4. Nanoporous materials from stable and metastable structures of 1,2-PB-b-PDMS block copolymers

    DEFF Research Database (Denmark)

    Schulte, Lars; Grydgaard, Anne; Jakobsen, Mathilde R.

    2011-01-01

    matrix component) and secondly degrading PDMS (the expendable component). Depending on the temperature of the cross-linking reaction different morphologies can be ‘frozen’ from the same block copolymer. Starting with a block copolymer precursor of lamellar morphology at room temperature, the gyroid...... structure or a metastable structure showing hexagonal symmetry (probably HPL) were permanently captured by cross-linking the precursor at 140 °C or at 85 °C, respectively. PDMS was degraded by reaction with tetrabutylamonium fluoride; considerations on the mechanism of cleaving reaction are presented....... The characterization of the materials at different stages of preparation includes gravimetry, infrared spectroscopy, small angle x-ray scattering, electron microscopy and isothermal nitrogen adsorption experiments....

  5. Human perspectives and conservation of grizzly bears in Banff National Park, Canada.

    Science.gov (United States)

    Chamberlain, Emily C; Rutherford, Murray B; Gibeau, Michael L

    2012-06-01

    Some conservation initiatives provoke intense conflict among stakeholders. The need for action, the nature of the conservation measures, and the effects of these measures on human interests may be disputed. Tools are needed to depolarize such situations, foster understanding of the perspectives of people involved, and find common ground. We used Q methodology to explore stakeholders' perspectives on conservation and management of grizzly bears (Ursus arctos horribilis) in Banff National Park and the Bow River watershed of Alberta, Canada. Twenty-nine stakeholders participated in the study, including local residents, scientists, agency employees, and representatives of nongovernmental conservation organizations and other interest groups. Participants rank ordered a set of statements to express their opinions on the problems of grizzly bear management (I-IV) and a second set of statements on possible solutions to the problems (A-C). Factor analysis revealed that participants held 4 distinct views of the problems: individuals associated with factor I emphasized deficiencies in goals and plans; those associated with factor II believed that problems had been exaggerated; those associated with factor III blamed institutional flaws such as disjointed management and inadequate resources; and individuals associated with factor IV blamed politicized decision making. There were 3 distinct views about the best solutions to the problems: individuals associated with factor A called for increased conservation efforts; those associated with factor B wanted reforms in decision-making processes; and individuals associated with factor C supported active landscape management. We connected people's definitions of the problem with their preferred solutions to form 5 overall problem narratives espoused by groups in the study: the problem is deficient goals and plans, the solution is to prioritize conservation efforts (planning-oriented conservation advocates); the problem is flawed

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

    CERN Document Server

    Qiu, Yinghua; Chen, Weiyu; Si, Wei; Tan, Qiyan; Chen, Yunfei

    2016-01-01

    Porous graphene has high mechanical strength and atomic layer thickness, which make it a promising material for material separation and biomolecule sensing. Electrostatic interactions between charges in aqueous solution are a kind of strong long-range interaction which may have great influence on the fluid transport through nanopores. Here, molecular dynamics simulations were conducted to investigate ion and water transport through a 1.05-nm-in-diameter monolayer graphene nanopore with its edge charge-modified. From the results, it is found that the 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 monotonously decrease. The co-ions rejection can reach 75% and 90% when the nanopores are negatively and positively charged, respectively. Cl ions current increases and reaches a plateau, and Na+ current decreases with the charge amount in the systems where they act as counterions. Beside...

  7. 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.

  8. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures

    OpenAIRE

    2011-01-01

    Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic...

  9. 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.

  10. Engineered nanoporous and nanostructured films

    Directory of Open Access Journals (Sweden)

    Joel L. Plawsky

    2009-06-01

    Full Text Available Nanoporous and nanostructured films have become increasingly important to the microelectronics and photonics industries. They provide a route to low dielectric constant materials that will enable future generations of powerful microprocessors. They are the only route to achieving materials with refractive indices less than 1.2, a key feature for the future development of photonic crystal devices, enhanced omni-directional reflectors, enhanced anti-reflection coatings and black-body absorbers. In addition, these films exhibit tremendous potential for separations, catalytic, biomedical and heat transfer applications. This article will review two primary techniques for manufacturing these films, evaporation induced self-assembly and oblique or glancing angle deposition, and will discuss some of the film properties critical to their use in the microelectronics and photonics industries.

  11. Nanocrystalline and Nanoporous Ceramics

    NARCIS (Netherlands)

    Verweij, Henk

    1996-01-01

    Nanocrystalline and nanoporous ceramics, renowned for their special transport properties, have typical applications in the fields of energy, the environment, and separation technology. One example is a solid oxide fuel cell, where an anode with improved characteristics was obtained by an optimized n

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

    Institute of Scientific and Technical Information of China (English)

    裘英华; 李堃; 陈伟宇; 司伟; 谭启檐; 陈云飞

    2015-01-01

    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 infl uence fl uid 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.

  13. Nanoporous GaN-Ag composite materials prepared by metal-assisted electroless etching for direct laser desorption-ionization mass spectrometry.

    Science.gov (United States)

    Nie, Bei; Duan, Barrett K; Bohn, Paul W

    2013-07-10

    Three-dimensional nanoporous gallium nitride(PGaN) produced by metal-assisted electroless etching is chemically embedded with silver nanoparticles via electroless deposition, forming a metallized semiconductor membrane with large surface area and nanoscale metal features. A new application utilizing the unique chemical and morphological features of these composite nanostructures is described here, laser induced desorption-ionization(LDI) of biomolecules(e.g., cholesterol and nucleotides) for direct mass analysis, without use of additional organic matrix. Although PGaN itself is a poor matrix for direct LDI mass spectrometry, the combination of Ag and PGaN greatly improves ion signals relative to PGaN or Ag nanostructure surfaces alone. This behavior is attributed to the combination of strong UV absorption, enhanced surface area, and favorable thermal properties of PGaN. Importantly, Ag-PGaN is shown to facilitate the formation of Ag adduct ions in some cases, for example adenine, where adducts are not observed from either porous anodic aluminum membranes or surfaces presenting Ag nanoparticles in isolation. Nanopore-embedded Ag nanostructures serve a dual role: as cationization agents and to assist thermal desorption under UV laser irradiation. The results reported here suggest that the combination of Ag nanostructures embedded in PGaN has the capacity for high quality matrix-free LDI mass analysis.

  14. 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...

  15. Weakened Flexural Strength of Nanocrystalline Nanoporous Gold by Grain Refinement.

    Science.gov (United States)

    Gwak, Eun-Ji; Kim, Ju-Young

    2016-04-13

    High density of grain boundaries in solid materials generally leads to high strength because grain boundaries act as strong obstacles to dislocation activity. We find that the flexural strength of nanoporous gold of grain size 206 nm is 33.6% lower than that of grain size 238 μm. We prepared three gold-silver precursor alloys, well-annealed, prestrained, and high-energy ball-milled, from which nanoporous gold samples were obtained by the same free-corrosion dealloying process. Ligaments of the same size are formed regardless of precursor alloys, and microstructural aspects of precursor alloys such as crystallographic orientation and grain size is preserved in the dealloying process. While the nanoindentation hardness of three nanoporous golds is independent of microstructural variation, flexural strength of nanocrystalline nanoporous gold is significantly lower than that of nanoporous golds with much larger grain size. We investigate weakening mechanisms of grain boundaries in nanocrystalline nanoporous gold, leading to weakening of flexural strength.

  16. Silicon Nanopore Devices for DNA Translocation and Sequencing Studies

    Science.gov (United States)

    Ling, Sean

    2005-03-01

    In this talk, I will discuss the recent progress [1-3] in developing solid-state nanopore devices using silicon technology. We have demonstrated a novel technique for shaping nanopores in the range of 1-10 nm, using surface-tension-driven mass flow with single nanometer precision. This technique overcomes a major technical challenge in silicon technology. I will also discuss the current effort [3] in developing integrated nanopore silicon chips with electrically addressable nanopores. These devices are used for DNA translocation and sequencing studies. This work was done in collaboration with the group of Cees Dekker at TU-Delft with partial support from FOM and Guggenheim Foundation. The work at Brown was supported by NSF-NER and NSF-NIRT. [1] A.J. Storm, J.H. Chen, X.S. Ling, H. Zandbergen, and C. Dekker, ``Fabrication of Solid-State Nanopores with Single Nanometer Precision'', Nature Materials, 2, 537 (2003). [2] A.J. Storm, J.H. Chen, X.S. Ling, H. Zandbergen, and C. Dekker, ``Electron-Beam-Induced Deformations of SiO2 Nanostructures'', Journal of Applied Physics (submitted, 2004). [3] X.S. Ling, "Addressable nanopores and micropores" (patent pending).

  17. Effects of adsorption and confinement on nanoporous electrochemistry.

    Science.gov (United States)

    Bae, Je Hyun; Han, Ji-Hyung; Han, Donghyeop; Chung, Taek Dong

    2013-01-01

    Characteristic molecular dynamics of reactant molecules confined in the space of the nanometer scale augments the frequency of collisions with the electrified surface so that a given faradaic reaction can be enhanced at nanoporous electrodes, the so-called nano-confinement effect. Since this effect is grounded on diffusion inside nanopores, it is predicted that adsorption onto the surface will seriously affect the enhancement by nano-confinement. We experimentally explored the correlation between adsorption and the confinement effect by examining the oxidation of butanol isomers at platinum and gold nanoporous electrodes. The results showed that electrooxidation of 2-butanol, which is a non-adsorption reaction, was enhanced more than that of 1-butanol, which is an adsorption reaction, at nanoporous platinum in acidic media. In contrast, the nanoporous gold electrode, on which 1-butanol is less adsorptive than it is on platinum, enhanced the electrooxidation of 1-butanol greatly. Furthermore, the electrocatalytic activity of nanoporous gold for oxygen reduction reaction was improved so much as to be comparable with that of flat Pt. These findings show that the nano-confinement effect can be appreciable for electrocatalytic oxygen reduction as well as alcohol oxidation unless the adsorption is extensive, and suggests a new strategy in terms of material design for innovative non-noble metal electrocatalysts.

  18. Carbon nanotube-based coatings to induce flow enhancement in hydrophilic nanopores

    DEFF Research Database (Denmark)

    Wagemann, Enrique; Walther, Jens Honore; Zambrano, Harvey

    2016-01-01

    that carbon nanotubes (CNTs) feature ultrafast waterflow rates which result in flow enhancements of 1 to 5 orders of magnitude compared to Hagen-Poiseuille predictions. In the present study, CNT-based coatings are considered to induce water flow enhancement in silica nanopores with different radius. We......-walled carbon nanotubes implemented as coating material in silica nanopores....

  19. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Science.gov (United States)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2009-12-29

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  20. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.

    2017-09-12

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  1. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2017-07-18

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  2. 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.

  3. 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.

  4. Ordered arrays of nanoporous gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2012-09-01

    Full Text Available A combination of a “top-down” approach (substrate-conformal imprint lithography and two “bottom-up” approaches (dewetting and dealloying enables fabrication of perfectly ordered 2-dimensional arrays of nanoporous gold nanoparticles. The dewetting of Au/Ag bilayers on the periodically prepatterned substrates leads to the interdiffusion of Au and Ag and the formation of an array of Au–Ag alloy nanoparticles. The array of alloy nanoparticles is transformed into an array of nanoporous gold nanoparticles by a following dealloying step. Large areas of this new type of material arrangement can be realized with this technique. In addition, this technique allows for the control of particle size, particle spacing, and ligament size (or pore size by varying the period of the structure, total metal layer thickness, and the thickness ratio of the as-deposited bilayers.

  5. Surface chemistry driven actuation in nanoporous gold

    Energy Technology Data Exchange (ETDEWEB)

    Biener, J; Wittstock, A; Zepeda-Ruiz, L; Biener, M M; Zielasek, V; Kramer, D; Viswanath, R N; Weissmuller, J; Baumer, M; Hamza, A V

    2008-04-14

    Although actuation in biological systems is exclusively powered by chemical energy, this concept has not been realized in man-made actuator technologies, as these rely on generating heat or electricity first. Here, we demonstrate that surface-chemistry driven actuation can be realized in high surface area materials such as nanoporous gold. For example, we achieve reversible strain amplitudes in the order of a few tenths of a percent by alternating exposure of nanoporous Au to ozone and carbon monoxide. The effect can be explained by adsorbate-induced changes of the surface stress, and can be used to convert chemical energy directly into a mechanical response thus opening the door to surface-chemistry driven actuator and sensor technologies.

  6. Effect of TiO2 Powder on the Surface Morphology of Micro/Nanoporous Structured Hydrophobic Fluoropolymer Based Composite Material

    Directory of Open Access Journals (Sweden)

    Bichitra Nanda Sahoo

    2013-01-01

    Full Text Available The present work reports a simple and effective way to produce hydrophobic foams with polyvinylidene fluoride (PVDF and TiO2 by using a phase separation technique. This method involved the phase separation during the deposition of PVDF from its DMF solution with nonsolvent water in the presence of TiO2. The surface morphology of hydrophobic surfaces was characterized by Field Emission Scanning Electron Microscope (FESEM. The maximum water contact angle of 129° was observed. The results confirm that the surface texture of polymer composite exhibits mixture of microporous and nanoporous structure. The impact of TiO2 on the wettability property of polymer composite has been studied. The proposed methodology might find applications in the preparation of hydrophobic surfaces for industrial applications.

  7. 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.

  8. Supervivencia del injerto renal según la categoría de Banff 2013 en biopsia por indicación

    Directory of Open Access Journals (Sweden)

    Carlos Arias-Cabrales

    2016-11-01

    Conclusiones: La clasificación de Banff 2013 permite el diagnóstico histológico en el 95% de las biopsias por indicación. La categoría 6 es la más frecuente, pero se observa una modificación en la histopatología predominante según el tiempo postrasplante. Los cambios mediados por anticuerpos se asocian con peor supervivencia del injerto.

  9. DNA-Based Nanopore Sensing.

    Science.gov (United States)

    Liu, Lei; Wu, Hai-Chen

    2016-12-05

    Nanopore sensing is an attractive, label-free approach that can measure single molecules. Although initially proposed for rapid and low-cost DNA sequencing, nanopore sensors have been successfully employed in the detection of a wide variety of substrates. Early successes were mostly achieved based on two main strategies by 1) creating sensing elements inside the nanopore through protein mutation and chemical modification or 2) using molecular adapters to enhance analyte recognition. Over the past five years, DNA molecules started to be used as probes for sensing rather than substrates for sequencing. In this Minireview, we highlight the recent research efforts of nanopore sensing based on DNA-mediated characteristic current events. As nanopore sensing is becoming increasingly important in biochemical and biophysical studies, DNA-based sensing may find wider applications in investigating DNA-involving biological processes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Vulnerability assessment of skiing-dependent businesses to the effects of climate change in Banff and Jasper National Parks, Canada

    Science.gov (United States)

    Reynolds, David Michael

    This qualitative study examines the potential positive and negative socio-economic impacts that may emerge from the long-term effects of climate change on skiing-dependent businesses in Banff and Jasper National Parks, Canada. My goal was to determine whether or not skiing-related tourism in the parks in the 2020s and 2050s is more or less socio-economically vulnerable to the effects of climate change on snow cover, temperatures and ski season length at ski resorts in the parks. My study explored the level of awareness and personal perceptions of 60 skiing-dependent business managers about how the impact of climate change on ski resorts may influence future socio-economics of ski tourism businesses. I employed a vulnerability assessment approach and adopted some elements of grounded theory. My primary data sources are interviews with managers and the outcome of the geographical factors index (GFI). Supporting methods include: an analysis and interpretation of climate model data and an interpretation of the economic analysis of skiing in the parks. The interview data were sorted and coded to establish concepts and findings by interview questions, while the GFI model rated and ranked 24 regional ski resorts in the Canadian Cordillera. The findings answered the research questions and helped me conclude what the future socio-economic vulnerability may be of skiing-dependent businesses in the parks. The interviews revealed that managers are not informed about climate change and they have not seen any urgency to consider the effects on business. The GFI revealed that the ski resorts in the parks ranked in the top ten of 24 ski resorts in the Cordillera based on 14 common geographical factors. The economic reports suggest skiing is the foundation of the winter economy in the parks and any impact on skiing would directly impact other skiing-dependent businesses. Research indicates that the effects of climate change may have less economic impact on skiing

  11. Catalytic Rapid Pyrolysis of Quercus variabilis over Nanoporous Catalysts

    Directory of Open Access Journals (Sweden)

    Hyeon Koo Kang

    2015-01-01

    Full Text Available Catalytic rapid pyrolysis of Quercus variabilis, a Korean native tree species, was carried out using Py-GC/MS. Mesoporous MFI, which has both nanopores and micropores, and three nanoporous materials, Al-MCM-41, Al-SBA-15, and γ-Al2O3, were used as the catalyst. The acid sites of mesoporous MFI were strong Brønsted acid sites, whereas those of nanoporous materials were mostly weak acid sites. The composition of the product bio-oil varied greatly depending on the acid characteristics of the catalyst used. Phenolics were the most abundant species in the bio-oil, followed by acids and furanics, obtained over Al-MCM-41 or Al-SBA-15 with weak acid sites, whereas aromatics were the most abundant species produced over mesoporous MFI with strong acid sites, followed by phenolics. Aromatics, phenolics, and furanics are all important chemicals contributing to the improvement of bio-oil quality.

  12. Engineered/tailored nanoporous gold structures for infrared plasmonics

    Science.gov (United States)

    Garoli, Denis; Calandrini, Eugenio; Cattarin, Sandro; Barison, Simona; Zilio, Pierfrancesco; Bozzola, Angelo; Toma, Andrea; De Angelis, Francesco

    2015-08-01

    Nanoporous gold is a very promising and novel material platform for mid-infrared and THz plasmonics. Nanoporous gold can be formed by dealloying of Au-Ag alloys, previously grown by means of Ag-Au co-sputtering. The optical response is completely determined by the nanostructural film features, that depends on the initial alloy composition and on the preparation procedure. The behavior of the material in mid-infrared and its peculiar morphology with a very high surface/volume ratio can be applied for nanostructure fabrication, such for example nanoantennas. Here we report the design and fabrication of nanoporous antennas engineered to support resonances in the 1500-1700 cm-1 range where them can be exploited, for example, in the detection of protein conformational states. This novel paradigm points toward the development of a new class of efficient and high-selective biosensors.

  13. Consequences of a refuge for the predator-prey dynamics of a wolf-elk system in Banff National Park, Alberta, Canada.

    Science.gov (United States)

    Goldberg, Joshua F; Hebblewhite, Mark; Bardsley, John

    2014-01-01

    Refugia can affect predator-prey dynamics via movements between refuge and non-refuge areas. We examine the influence of a refuge on population dynamics in a large mammal predator-prey system. Wolves (Canis lupus) have recolonized much of their former range in North America, and as a result, ungulate prey have exploited refugia to reduce predation risk with unknown impacts on wolf-prey dynamics. We examined the influence of a refuge on elk (Cervus elaphus) and wolf population dynamics in Banff National Park. Elk occupy the Banff townsite with little predation, whereas elk in the adjoining Bow Valley experience higher wolf predation. The Banff refuge may influence Bow Valley predator-prey dynamics through source-sink movements. To test this hypothesis, we used 26 years of wolf and elk population counts and the Delayed Rejection Adaptive Metropolis Markov chain Monte Carlo method to fit five predator-prey models: 1) with no source-sink movements, 2) with elk density-dependent dispersal from the refuge to the non-refuge, 3) with elk predation risk avoidance movements from the non-refuge to the refuge, 4) with differential movement rates between refuge and non-refuge, and 5) with short-term, source-sink wolf movements. Model 1 provided the best fit of the data, as measured by Akaike Information Criterion (AIC). In the top model, Banff and Bow Valley elk had median growth rates of 0.08 and 0.03 (95% credibility intervals [CIs]: 0.027-0.186 and 0.001-0.143), respectively, Banff had a median carrying capacity of 630 elk (95% CI: 471.9-2676.9), Bow Valley elk had a median wolf encounter rate of 0.02 (95% CI: 0.013-0.030), and wolves had a median death rate of 0.23 (95% CI: 0.146-0.335) and a median conversion efficiency of 0.07 (95% CI: 0.031-0.124). We found little evidence for potential source-sink movements influencing the predator-prey dynamics of this system. This result suggests that the refuge was isolated from the non-refuge.

  14. Consequences of a refuge for the predator-prey dynamics of a wolf-elk system in Banff National Park, Alberta, Canada.

    Directory of Open Access Journals (Sweden)

    Joshua F Goldberg

    Full Text Available Refugia can affect predator-prey dynamics via movements between refuge and non-refuge areas. We examine the influence of a refuge on population dynamics in a large mammal predator-prey system. Wolves (Canis lupus have recolonized much of their former range in North America, and as a result, ungulate prey have exploited refugia to reduce predation risk with unknown impacts on wolf-prey dynamics. We examined the influence of a refuge on elk (Cervus elaphus and wolf population dynamics in Banff National Park. Elk occupy the Banff townsite with little predation, whereas elk in the adjoining Bow Valley experience higher wolf predation. The Banff refuge may influence Bow Valley predator-prey dynamics through source-sink movements. To test this hypothesis, we used 26 years of wolf and elk population counts and the Delayed Rejection Adaptive Metropolis Markov chain Monte Carlo method to fit five predator-prey models: 1 with no source-sink movements, 2 with elk density-dependent dispersal from the refuge to the non-refuge, 3 with elk predation risk avoidance movements from the non-refuge to the refuge, 4 with differential movement rates between refuge and non-refuge, and 5 with short-term, source-sink wolf movements. Model 1 provided the best fit of the data, as measured by Akaike Information Criterion (AIC. In the top model, Banff and Bow Valley elk had median growth rates of 0.08 and 0.03 (95% credibility intervals [CIs]: 0.027-0.186 and 0.001-0.143, respectively, Banff had a median carrying capacity of 630 elk (95% CI: 471.9-2676.9, Bow Valley elk had a median wolf encounter rate of 0.02 (95% CI: 0.013-0.030, and wolves had a median death rate of 0.23 (95% CI: 0.146-0.335 and a median conversion efficiency of 0.07 (95% CI: 0.031-0.124. We found little evidence for potential source-sink movements influencing the predator-prey dynamics of this system. This result suggests that the refuge was isolated from the non-refuge.

  15. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures

    Directory of Open Access Journals (Sweden)

    Jaydeep Bhattacharya

    2011-02-01

    Full Text Available Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.

  16. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures.

    Science.gov (United States)

    Bhattacharya, Jaydeep; Kisner, Alexandre; Offenhäusser, Andreas; Wolfrum, Bernhard

    2011-01-01

    Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.

  17. Ionic selectivity of nystatin A1 confined in nanoporous track-etched polymer membrane.

    Science.gov (United States)

    Balme, Sébastien; Thiele, Daniela; Kraszewski, Sebastian; Picaud, Fabien; Janot, Jean-Marc; Déjardin, Philippe

    2014-09-01

    The hybrid biological/polymeric solid-state nanopore membrane offers several opportunities to combine the advantage of biological channel (selectivity) and material (robustness). Based on this technology, the challenge is to obtain selective ionic exchange membranes, with no energy intake. The direct insertion of an ionic channel inside a nanopore should be a promise solution. Here, the authors report a hybrid nanopore based on nystatin A1 confinement in commercial nanopore membrane. Ionic transport and selectivity studies show that the hybrid nanopores exhibit mainly an anionic behaviour, on the contrary to biological conditions. However, the order of magnitude between the different ratios of permeation of several cationic species is retained even if the blocking of divalent cation is not totally proved.

  18. Localized functionalization of single nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, J; Lee, J I; Ratto, T V; Letant, S E

    2005-09-12

    We demonstrate the localization of chemical functionality at the entrance of single nanopores for the first time by using the controlled growth of an oxide ring. Nanopores were fabricated by Focused Ion Beam machining on silicon platforms, locally derivatized by ion beam assisted oxide deposition, and further functionalized with DNA probes via silane chemistry. Ionic current recorded through single nanopores at various stages of the fabrication process demonstrated that the apertures can be locally functionalized with DNA probes. Future applications for this functional platform include the selective detection of biological organisms and molecules by ionic current blockade measurements.

  19. SEM-induced shrinkage and site-selective modification of single-crystal silicon nanopores

    Science.gov (United States)

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

    2017-07-01

    Solid-state nanopores with feature sizes around 5 nm play a critical role in bio-sensing fields, especially in single molecule detection and sequencing of DNA, RNA and proteins. In this paper we present a systematic study on shrinkage and site-selective modification of single-crystal silicon nanopores with a conventional scanning electron microscope (SEM). Square nanopores with measurable sizes as small as 8 nm × 8 nm and rectangle nanopores with feature sizes (the smaller one between length and width) down to 5 nm have been obtained, using the SEM-induced shrinkage technique. The analysis of energy dispersive x-ray spectroscopy and the recovery of the pore size and morphology reveal that the grown material along with the edge of the nanopore is the result of deposition of hydrocarbon compounds, without structural damage during the shrinking process. A simplified model for pore shrinkage has been developed based on observation of the cross-sectional morphology of the shrunk nanopore. The main factors impacting on the task of controllably shrinking the nanopores, such as the accelerating voltage, spot size, scanned area of e-beam, and the initial pore size have been discussed. It is found that single-crystal silicon nanopores shrink linearly with time under localized irradiation by SEM e-beam in all cases, and the pore shrinkage rate is inversely proportional to the initial equivalent diameter of the pore under the same e-beam conditions.

  20. Nanopore and nanoparticle catalysts.

    Science.gov (United States)

    Thomas, J M; Raja, R

    2001-01-01

    The design, atomic characterization, performance, and relevance to clean technology of two distinct categories of new nanocatalysts are described and interpreted. Exceptional molecular selectivity and high activity are exhibited by these catalysts. The first category consists of extended, crystallographically ordered inorganic solids possessing nanopores (apertures, cages, and channels), the diameters of which fall in the range of about 0.4 to about 1.5 nm, and the second of discrete bimetallic nanoparticles of diameter 1 to 2 nm, distributed more or less uniformly along the inner walls of mesoporous (ca. 3 to 10 nm diameter) silica supports. Using the principles and practices of solid-state and organometallic chemistry and advanced physico-chemical techniques for in situ and ex situ characterization, a variety of powerful new catalysts has been evolved. Apart from those that, inter alia, simulate the behavior of enzymes in their specificity, shape selectivity, regio-selectivity, and ability to function under ambient conditions, many of these new nanocatalysts are also viable as agents for effecting commercially significant processes in a clean, benign, solvent-free, single-step fashion. In particular, a bifunctional, molecular sieve nanopore catalyst is described that converts cyclohexanone in air and ammonia to its oxime and caprolactam, and a bimetallic nanoparticle catalyst that selectively converts cyclic polyenes into desirable intermediates. Nanocatalysts in the first category are especially effective in facilitating highly selective oxidations in air, and those in the second are well suited to effecting rapid and selective hydrogenations of a range of organic compounds.

  1. Synthesis of Nanoporous Metals, Oxides, Carbides, and Sulfides: Beyond Nanocasting.

    Science.gov (United States)

    Luc, Wesley; Jiao, Feng

    2016-07-19

    Nanoporous metal-based solids are of particular interest because they combine a large quantity of surface metal sites, interconnected porous networks, and nanosized crystalline walls, thus exhibiting unique physical and chemical properties compared to other nanostructures and bulk counterparts. Among all of the synthetic approaches, nanocasting has proven to be a highly effective method for the syntheses of metal oxides with three-dimensionally ordered porous structures and crystalline walls. A typical procedure involves a thermal annealing process of a porous silica template filled with an inorganic precursor (often a metal nitrate salt), which converts the precursor into a desired phase within the silica pores. The final step is the selective removal of the silica template in either a strong base or a hydrofluoric acid solution. In the past decade, nanocasting has become a popular synthetic approach and has enabled the syntheses of a variety of nanoporous metal oxides. However, there is still a lack of synthetic methods to fabricate nanoporous materials beyond simple metal oxides. Therefore, the development of new synthetic strategies beyond nanocasting has become an important direction. This Account describes new progress in the preparation of novel nanoporous metal-based solids for heterogeneous catalysis. The discussion begins with a method called dealloying, an effective method to synthesize nanoporous metals. The starting material is a metallic alloy containing two or more elements followed by a selective chemical or electrochemical leaching process that removes one of the preferential elements, resulting in a highly porous structure. Nanoporous metals, such as Cu, Ag, and CuTi, exhibit remarkable electrocatalytic properties in carbon dioxide reduction, oxygen reduction, and hydrogen evolution reactions. In addition, the syntheses of metal oxides with hierarchical porous structures are also discussed. On the basis of the choice of hard template, nanoporous

  2. Nanoporous surfaces via impact of molten metallic droplets

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Meng [Massachusetts Institute of Technology, Department of Materials Science and Engineering, Cambridge, MA (United States); Colmenares, Jose R.; Valarezo, Alfredo [State University of New York, Stony Brook (United States). Center for Thermal Spray Research; Gouldstone, Andrew [Northeastern University, Department of Mechanical and Industrial Engineering, Boston, MA (United States)

    2009-08-15

    Here we describe a new pathway for the production of nanoporous surfaces, by recourse to molten droplet impact and solidification. The nanopores in this case are frozen in bubbles that nucleate in the melt due to gas supersaturation within 100 nanoseconds of impact. Initial observations and previous analysis are presented, as well as ongoing work to control or pattern porosity via process variation and substrate pre-treatment. This method is presumably not limited in material, and has potential to create large area, functional surfaces. (orig.)

  3. Surface Modification of Nanoporous 1,2-Polybutadiene by Atom Transfer Radical Polymerization or Click Chemistry

    DEFF Research Database (Denmark)

    Guo, Fengxiao; Jankova Atanasova, Katja; Schulte, Lars;

    2010-01-01

    ATRP-grafting of hydrophilic polyacrylates and click of MPEG, the originally hydrophobic samples transformed into hydrophilic nanoporous materials. The successful modification was confirmed by infrared spectroscopy, contact angle measurements and measurements of spontaneous water uptake, while...

  4. Noise and its reduction in graphene based nanopore devices.

    Science.gov (United States)

    Kumar, Ashvani; Park, Kyeong-Beom; Kim, Hyun-Mi; Kim, Ki-Bum

    2013-12-13

    Ionic current fluctuations in graphene nanopore devices are a ubiquitous phenomenon and are responsible for degraded spatial and temporal resolution. Here, we descriptively investigate the impact of different substrate materials (Si and quartz) and membrane thicknesses on noise characteristics of graphene nanopore devices. To mitigate the membrane fluctuations and pin-hole defects, a SiNx membrane is transferred onto the substrate and a pore of approximately 70 nm in diameter is perforated prior to the graphene transfer. Comprehensive noise study reveals that the few layer graphene transferred onto the quartz substrate possesses low noise level and higher signal to noise ratio as compared to single layer graphene, without deteriorating the spatial resolution. The findings here point to improvement of graphene based nanopore devices for exciting opportunities in future single-molecule genomic screening devices.

  5. Preparation and Photocatalytic Characterization of Nanoporous TiO2

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Nanoporous TiO2 photocatalysts were prepared by use of controlled drying method with surfactants. The surface area and porous properties are dependent on the chain length of incorporated surfactant cation. The TiO2 materials prepared in the presence of surfactant molecules during the gel formation exhibit much higher photocatalytic activity than that prepared in the absence of surfactants.

  6. Structure-property relations of gold and graphene nanoporous actuators

    NARCIS (Netherlands)

    Saane, Siva Shankar Reddy

    2015-01-01

    Electrochemical nanoporous actuators have low weight, large specific surface areas and low voltage operating capabilities, making them attractive for application in small-scale electromechanical devices. The actuation strain of these materials at the macroscopic scale is a manifestation of microscop

  7. Topological defects: origin of nanopores and enhanced adsorption performance in nanoporous carbon.

    Science.gov (United States)

    Guo, Junjie; Morris, James R; Ihm, Yungok; Contescu, Cristian I; Gallego, Nidia C; Duscher, Gerd; Pennycook, Stephen J; Chisholm, Matthew F

    2012-11-05

    A scanning transmission electron microscopy investigation of two nanoporous carbon materials, wood-based ultramicroporous carbon and poly(furfuryl alcohol)-derived carbon, is reported. Atomic-resolution images demonstrate they comprise isotropic, three-dimensional networks of wrinkled one-atom-thick graphene sheets. In each graphene plane, nonhexagonal defects are frequently observed as connected five- and seven-atom rings. Atomic-level modeling shows that these topological defects induce localized rippling of graphene sheets, which interferes with their graphitic stacking and induces nanopores that lead to enhanced adsorption of H(2) molecules. The poly(furfuryl alcohol)-derived carbon contains larger regions of stacked layers, and shows significantly smaller surface area and pore volume than the ultramicroporous carbon.

  8. 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....

  9. Noise Properties of Rectifying Nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Powell, M R; Sa, N; Davenport, M; Healy, K; Vlassiouk, I; Letant, S E; Baker, L A; Siwy, Z S

    2011-02-18

    Ion currents through three types of rectifying nanoporous structures are studied and compared for the first time: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit non-equilibrium 1/f noise, thus the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, including intrinsic pore wall dynamics, and formation of vortices and non-linear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields inducing secondary effects in the pore such as enhanced water dissociation.

  10. Estimating grizzly and black bear population abundance and trend in Banff National Park using noninvasive genetic sampling.

    Directory of Open Access Journals (Sweden)

    Michael A Sawaya

    Full Text Available We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos and black bear (U. americanus populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears (N= 73.5, 95% CI = 64-94 in 2006; N= 50.4, 95% CI = 49-59 in 2008 and black bears (N= 62.6, 95% CI = 51-89 in 2006; N= 81.8, 95% CI = 72-102 in 2008 in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males (λ= 0.93, 95% CI = 0.74-1.17 and females (λ= 0.90, 95% CI = 0.67-1.20 using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains.

  11. Estimating grizzly and black bear population abundance and trend in Banff National Park using noninvasive genetic sampling.

    Science.gov (United States)

    Sawaya, Michael A; Stetz, Jeffrey B; Clevenger, Anthony P; Gibeau, Michael L; Kalinowski, Steven T

    2012-01-01

    We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos) and black bear (U. americanus) populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears (N= 73.5, 95% CI = 64-94 in 2006; N= 50.4, 95% CI = 49-59 in 2008) and black bears (N= 62.6, 95% CI = 51-89 in 2006; N= 81.8, 95% CI = 72-102 in 2008) in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males (λ= 0.93, 95% CI = 0.74-1.17) and females (λ= 0.90, 95% CI = 0.67-1.20) using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains.

  12. 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.

  13. Specific Energy Characteristics of Nanoporous Carbon Activated by Orthophosphoric Acid

    Directory of Open Access Journals (Sweden)

    B.I. Rachiy

    2015-12-01

    Full Text Available This paper investigated the effect of the amount of phosphoric acid on the structure nanoporous carbon materials (NCM obtained from raw materials of plant origin. The results voltammetry defined specific capacitance characteristics of NCM and conditions its synthesis with optimal energy parameters established. It is shown that reducing the number of lignin-cellulose materials in precursor volume due to carbonization leads to a decline in specific capacity of NCM approximately 6-20 %.

  14. Nanoporous carbon tunable resistor/transistor and methods of production thereof

    Energy Technology Data Exchange (ETDEWEB)

    Biener, Juergen; Baumann, Theodore F; Dasgupta, Subho; Hahn, Horst

    2014-04-22

    In one embodiment, a tunable resistor/transistor includes a porous material that is electrically coupled between a source electrode and a drain electrode, wherein the porous material acts as an active channel, an electrolyte solution saturating the active channel, the electrolyte solution being adapted for altering an electrical resistance of the active channel based on an applied electrochemical potential, wherein the active channel comprises nanoporous carbon arranged in a three-dimensional structure. In another embodiment, a method for forming the tunable resistor/transistor includes forming a source electrode, forming a drain electrode, and forming a monolithic nanoporous carbon material that acts as an active channel and selectively couples the source electrode to the drain electrode electrically. In any embodiment, the electrolyte solution saturating the nanoporous carbon active channel is adapted for altering an electrical resistance of the nanoporous carbon active channel based on an applied electrochemical potential.

  15. Nanoporous carbon tunable resistor/transistor and methods of production thereof

    Science.gov (United States)

    Biener, Juergen; Baumann, Theodore F; Dasgupta, Subho; Hahn, Horst

    2014-04-22

    In one embodiment, a tunable resistor/transistor includes a porous material that is electrically coupled between a source electrode and a drain electrode, wherein the porous material acts as an active channel, an electrolyte solution saturating the active channel, the electrolyte solution being adapted for altering an electrical resistance of the active channel based on an applied electrochemical potential, wherein the active channel comprises nanoporous carbon arranged in a three-dimensional structure. In another embodiment, a method for forming the tunable resistor/transistor includes forming a source electrode, forming a drain electrode, and forming a monolithic nanoporous carbon material that acts as an active channel and selectively couples the source electrode to the drain electrode electrically. In any embodiment, the electrolyte solution saturating the nanoporous carbon active channel is adapted for altering an electrical resistance of the nanoporous carbon active channel based on an applied electrochemical potential.

  16. 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

  17. 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.

  18. Nanoporous materials: pillared clays and regular silicas as an example of synthesis and their porosity characterization by X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Pires, Joao, E-mail: jpsilva@fc.ul.pt [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa (Portugal)

    2014-07-01

    Because of their practical applications, porous materials attract the attention of undergraduate students in a way that can be used to teach techniques and concepts in various chemistry disciplines. Porous materials are studied in various chemistry disciplines, including inorganic, organic, and physical chemistry. In this work, the syntheses of a microporous material and a mesoporous material are presented. The porosity of the synthesized materials is characterized by X-ray diffraction analysis. We show that this technique can be used to determine the pore dimensions of the synthesized materials. (author)

  19. 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.

  20. Highly active thermally stable nanoporous gold catalyst

    Science.gov (United States)

    Biener, Juergen; Wittstock, Arne; Biener, Monika M.; Bagge-Hansen, Michael; Baeumer, Marcus; Wichmann, Andre; Neuman, Bjoern

    2016-12-20

    In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

  1. Highly active thermally stable nanoporous gold catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Biener, Juergen; Wittstock, Arne; Biener, Monika M.; Bagge-Hansen, Michael; Baeumer, Marcus; Wichmann, Andre; Neuman, Bjoern

    2016-12-20

    In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

  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 triangles...

  3. Multiplexed ionic current sensing with glass nanopores.

    Science.gov (United States)

    Bell, Nicholas A W; Thacker, Vivek V; Hernández-Ainsa, Silvia; Fuentes-Perez, Maria E; Moreno-Herrero, Fernando; Liedl, Tim; Keyser, Ulrich F

    2013-05-21

    We report a method for simultaneous ionic current measurements of single molecules across up to 16 solid state nanopore channels. Each device, costing less than $20, contains 16 glass nanopores made by laser assisted capillary pulling. We demonstrate simultaneous multichannel detection of double stranded DNA and trapping of DNA origami nanostructures to form hybrid nanopores.

  4. Cavitation and pore blocking in nanoporous glasses.

    Science.gov (United States)

    Reichenbach, C; Kalies, G; Enke, D; Klank, D

    2011-09-06

    In gas adsorption studies, porous glasses are frequently referred to as model materials for highly disordered mesopore systems. Numerous works suggest that an accurate interpretation of physisorption isotherms requires a complete understanding of network effects upon adsorption and desorption, respectively. The present article deals with nitrogen and argon adsorption at different temperatures (77 and 87 K) performed on a series of novel nanoporous glasses (NPG) with different mean pore widths. NPG samples contain smaller mesopores and significantly higher microporosity than porous Vycor glass or controlled pore glass. Since the mean pore width of NPG can be tuned sensitively, the evolution of adsorption characteristics with respect to a broadening pore network can be investigated starting from the narrowest nanopore width. With an increasing mean pore width, a H2-type hysteresis develops gradually which finally transforms into a H1-type. In this connection, a transition from a cavitation-induced desorption toward desorption controlled by pore blocking can be observed. Furthermore, we find concrete hints for a pore size dependence of the relative pressure of cavitation in highly disordered pore systems. By comparing nitrogen and argon adsorption, a comprehensive insight into adsorption mechanisms in novel disordered materials is provided.

  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. Quantum Capacitance Modifies Interionic Interactions in Semiconducting Nanopores

    CERN Document Server

    Lee, Alpha A; Goriely, Alain

    2016-01-01

    Nanopores made with low dimensional semiconducting materials, such as carbon nanotubes and graphene slit pores, are used in supercapacitors. In theories and simulations of their operation, it is often assumed that such pores screen ion-ion interactions like metallic pores, i.e. that screening leads to an exponential decay of the interaction potential with ion separation. By introducing a quantum capacitance that accounts for the density of states in the material, we show that ion-ion interactions in carbon nanotubes and graphene slit pores actually decay algebraically with ion separation. This result suggests a new avenue of capacitance optimization based on tuning the electronic structure of a pore: a marked enhancement in capacitance might be achieved by developing nanopores made with metallic materials or bulk semimetallic materials.

  7. Ultrathin suspended nanopores with surface plasmon resonance fabricated by combined colloidal lithography and film transfer.

    Science.gov (United States)

    Junesch, Juliane; Sannomiya, Takumi

    2014-05-14

    Suspended plasmonic nanopores in ultrathin film layers were fabricated through a simple and widely applicable method combining colloidal lithography and thin film transfer, which allows mass production of short-range ordered nanopore arrays on a large scale. By this combined method, mechanically stable and flexible free-standing nanopore membranes with a thickness down to 15-30 nm were produced. The plasmon resonances of the ultrathin plasmonic nanopores fabricated in AlN/Au/AlN trilayer and single layer Au membranes were tuned to lie in the vis-NIR wavelength range by properly designing their dimensions. The optical responses to the refractive index changes were tested and applied to adlayer sensing. The trilayer nanopore membrane showed a unique property to support water only on one side of the membrane, which was confirmed by the resonance shift and comparison with numerical simulation. Pore size reduction down to 10 nm can be achieved through additional material deposition. The filtering function of such pore-size-reduced conical shaped nanofunnels has also been demonstrated. The presented nanopore fabrication method offers new platforms for ultrathin nanopore sensing or filtering devices with controlled pore-size and optical properties. The film transfer technique employed in this work would enable the transformation of any substrate-based nanostructures to free-standing membrane based devices without complicated multiple etching processes.

  8. Atomic layer deposition of nanoporous biomaterials

    Directory of Open Access Journals (Sweden)

    Roger J Narayan

    2010-03-01

    Full Text Available 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.

  9. Nanopore-CMOS Interfaces for DNA Sequencing.

    Science.gov (United States)

    Magierowski, Sebastian; Huang, Yiyun; Wang, Chengjie; Ghafar-Zadeh, Ebrahim

    2016-08-06

    DNA sequencers based on nanopore sensors present an opportunity for a significant break from the template-based incumbents of the last forty years. Key advantages ushered by nanopore technology include a simplified chemistry and the ability to interface to CMOS technology. The latter opportunity offers substantial promise for improvement in sequencing speed, size and cost. This paper reviews existing and emerging means of interfacing nanopores to CMOS technology with an emphasis on massively-arrayed structures. It presents this in the context of incumbent DNA sequencing techniques, reviews and quantifies nanopore characteristics and models and presents CMOS circuit methods for the amplification of low-current nanopore signals in such interfaces.

  10. 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.

  11. DNA Translocation through Graphene Nanopores

    CERN Document Server

    Schneider, Grégory F; Calado, Victor E; Pandraud, Grégory; Zandbergen, Henny W; Vandersypen, Lieven M K; Dekker, Cees

    2010-01-01

    Nanopores -- nanosized holes that can transport ions and molecules -- are very promising devices for genomic screening, in particular DNA sequencing. Both solid-state and biological pores suffer from the drawback, however, that the channel constituting the pore is long, viz. 10-100 times the distance between two bases in a DNA molecule (0.5 nm for single-stranded DNA). Here, we demonstrate that it is possible to realize and use ultrathin nanopores fabricated in graphene monolayers for single-molecule DNA translocation. The pores are obtained by placing a graphene flake over a microsize hole in a silicon nitride membrane and drilling a nanosize hole in the graphene using an electron beam. As individual DNA molecules translocate through the pore, characteristic temporary conductance changes are observed in the ionic current through the nanopore, setting the stage for future genomic screening.

  12. Switchable Imbibition in Nanoporous Gold

    CERN Document Server

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

    2014-01-01

    Spontaneous imbibition enables the elegant propelling of nano-flows because of the dominance of capillarity at small length scales. The imbibition kinetics are, however, solely determined by the static geometry of the porous host, the capillarity, and the fluidity of the imbibed liquid. This makes active control particularly challenging. Here, 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, i.e. we can accelerate the imbibition front, stop it, and have it proceed at will. Simultaneous measurements of the mass flux and the electrical current allow us to document simple scaling laws for the imbibition kinetics, and to explore the charge flow dynamics in the metallic nanopores. Our findings demonstrate that the high electric conductivity along with the pathways for ionic and/or fluid transport render nanoporous elemental gold a versatile, accurately controllable elec...

  13. Adsorption hysteresis in nanopores

    Science.gov (United States)

    Neimark; Ravikovitch; Vishnyakov

    2000-08-01

    Capillary condensation hysteresis in nanopores is studied by Monte Carlo simulations and the nonlocal density functional theory. Comparing the theoretical results with the experimental data on low temperature sorption of nitrogen and argon in cylindrical channels of mesoporous siliceous molecular sieves of MCM-41 type, we have revealed four qualitatively different sorption regimes depending on the temperature and pore size. As the pore size increases at a given temperature, or as the temperature decreases at a given pore size, the following regimes are consequently observed: volume filling without phase separation, reversible stepwise capillary condensation, irreversible capillary condensation with developing hysteresis, and capillary condensation with developed hysteresis. We show that, in the regime of developed hysteresis (pores wider than 5 nm in the case of nitrogen sorption at 77 K), condensation occurs spontaneously at the vaporlike spinodal while desorption takes place at the equilibrium. A quantitative agreement is found between the modeling results and the experimental hysteresis loops formed by the adsorption-desorption isotherms. The results obtained provide a better understanding of the general behavior of confined fluids and the specifics of sorption and phase transitions in nanomaterials.

  14. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    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...... functional nanoporous polymers based on nanoporous 1,2- polybuatdiene 1,2-PB, which is derived from a 1,2-PB-b-PDMS diblock copolymer precursor. As a result, nanoporous 1,2-PB with pores decorated of polyacrylates, sulfonated polymers and poly(ethylene glycol) are created. A method of vapor phase deposition...... has also been generated to obtain nanoporous polymers with functional coatings on pore walls. Vapor phase polymerization of pyrrole is performed to incorporate an ultra thin film of polypyrrole into nanoporous 1,2-PB. The preliminary test shows that nanoporous 1,2-PB gains conductivity. Generally...

  15. Enantioselective Nanoporous Carbon Based on Chiral Ionic Liquids.

    Science.gov (United States)

    Fuchs, Ido; Fechler, Nina; Antonietti, Markus; Mastai, Yitzhak

    2016-01-04

    One of the greatest challenges in modern chemical processing is to achieve enantiospecific control in chemical reactions using chiral media such as chiral mesoporous materials. Herein, we describe a novel and effective synthetic pathway for the preparation of enantioselective nanoporous carbon, based on chiral ionic liquids (CILs). CILs of phenylalanine (CIL(Phe)) are used as precursors for the carbonization of chiral mesoporous carbon. We employ circular dichroism spectroscopy, isothermal titration calorimetry (ITC), and chronoamperometry in order to demonstrate the chiral nature of the mesoporous carbon. The approach presented in this paper is highly significant for the development of a new type of chiral porous materials for enantioselective chemistry. In addition, it contributes significantly to our understanding of the structure and nature of chiral nanoporous materials and surfaces. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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.

  17. 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.

  18. Affinity transformation from hydrophilicity to hydrophobicity of water molecules on the basis of adsorption of water in graphitic nanopores.

    Science.gov (United States)

    Ohba, Tomonori; Kanoh, Hirofumi; Kaneko, Katsumi

    2004-02-11

    The interaction of water with hydrophobic surfaces is quite important in a variety of chemical and biochemical phenomena. The coexistence of water and oil can be realized by introduction of surfactants. In the case of water vapor adsorption on graphitic nanopores, plenty of water can be adsorbed in graphitic nanopores without surfactants, although the graphitic surface is not hydrophilic. Why are water molecules adsorbed in hydrophobic nanopores remarkably? This work can give an explicit insight to water adsorption in hydrophobic graphite nanopores using experimental and theoretical approaches. Water molecules are associated with each other to form the cluster of 1 nm in size, leading to a significant stabilization of the cluster in the graphitic nanopores. This mechanism can be widely applied to interfacial phenomena relating to coexistence of water and nanostructural materials of hydrophobicity.

  19. Surface-modified silica colloidal crystals: nanoporous films and membranes with controlled ionic and molecular transport.

    Science.gov (United States)

    Zharov, Ilya; Khabibullin, Amir

    2014-02-18

    Nanoporous membranes are important for the study of the transport of small molecules and macromolecules through confined spaces and in applications ranging from separation of biomacromolecules and pharmaceuticals to sensing and controlled release of drugs. For many of these applications, chemists need to gate the ionic and molecular flux through the nanopores, which in turn depends on the ability to control the nanopore geometry and surface chemistry. Most commonly used nanoporous membrane materials are based on polymers. However, the nanostructure of polymeric membranes is not well-defined, and their surface is hard to modify. Inorganic nanoporous materials are attractive alternatives for polymers in the preparation of nanoporous membranes. In this Account, we describe the preparation and surface modification of inorganic nanoporous films and membranes self-assembled from silica colloidal spheres. These spheres form colloidal crystals with close-packed face centered cubic lattices upon vertical deposition from colloidal solutions. Silica colloidal crystals contain ordered arrays of interconnected three dimensional voids, which function as nanopores. We can prepare silica colloidal crystals as supported thin films on various flat solid surfaces or obtain free-standing silica colloidal membranes by sintering the colloidal crystals above 1000 °C. Unmodified silica colloidal membranes are capable of size-selective separation of macromolecules, and we can surface-modify them in a well-defined and controlled manner with small molecules and polymers. For the surface modification with small molecules, we use silanol chemistry. We grow polymer brushes with narrow molecular weight distribution and controlled length on the colloidal nanopore surface using atom transfer radical polymerization or ring-opening polymerization. We can control the flux in the resulting surface-modified nanoporous films and membranes by pH and ionic strength, temperature, light, and small molecule

  20. Using Focused Electron Beams to Drill Straight Nanopores on a Membrane

    Directory of Open Access Journals (Sweden)

    Yung-Cheng Wang

    2014-08-01

    Full Text Available A high-resolution focused electron beam is used for the fabrication of metal nanostructures and devices with insulating membranes by nanosculpting metal films. This top-down focused electron beam drilling method uses the controlled ablation of materials to produce nanoscale devices with near-atomic precision of order. Using the proposed procedure, nano-drilling is not directly realized through the aperture, but by using a focused electron beam to burn away the solvent. Recent studies have investigated silicon nitride nanopores with an hourglass profile and silica nanopores with a pyramid-shaped cross-section, but electronic drilling in these approaches failed to produce straight nanopores. A method is proposed to improve the membranes’ thermal conductivity to rapidly produce straight nanopores, and is experimentally confirmed and has significant potential for use in nano-sensors or nano-devices.

  1. Mechanical properties of nanoporous graphene membrane

    Science.gov (United States)

    Liu, Yilun; Chen, Xi

    2014-01-01

    Nanoporous graphene holds great promise in the application of filtration such as seawater desalination, gas separation, and ionic channels. In this paper, we study the mechanical properties of nanoporous graphene with different size, shape, and density of nanopore. The strength decreases as the size and porosity of the nanopore increases. However, the rough edges of the nanopore has significant influence to the strength where the blunt tip perpendicular to the loading direction has higher strength. The effective tensile modulus is only determined by porosity of the nanopore as ΔE ˜ -p0.64, while the strength is determined by the size, shape, and porosity of the nanopore, for the same type of nanopore the strength scales with the porosity as Δσs ˜ -p. In contrast, the effective fracture strain increases as porosity increases for small and moderate porosities. The work is a first study of the relation between mechanical properties and porosity of nanoporous graphene and is helpful to the design of high performance nanoporous graphene membrane.

  2. Superdiffusive gas recovery from nanopores

    Science.gov (United States)

    Wu, Haiyi; He, Yadong; Qiao, Rui

    2016-11-01

    Understanding the recovery of gas from reservoirs featuring pervasive nanopores is essential for effective shale gas extraction. Classical theories cannot accurately predict such gas recovery and many experimental observations are not well understood. Here we report molecular simulations of the recovery of gas from single nanopores, explicitly taking into account molecular gas-wall interactions. We show that, in very narrow pores, the strong gas-wall interactions are essential in determining the gas recovery behavior both quantitatively and qualitatively. These interactions cause the total diffusion coefficients of the gas molecules in nanopores to be smaller than those predicted by kinetic theories, hence slowing down the rate of gas recovery. These interactions also lead to significant adsorption of gas molecules on the pore walls. Because of the desorption of these gas molecules during gas recovery, the gas recovery from the nanopore does not exhibit the usual diffusive scaling law (i.e., the accumulative recovery scales as R ˜t1 /2 ) but follows a superdiffusive scaling law R ˜tn (n >0.5 ), which is similar to that observed in some field experiments. For the system studied here, the superdiffusive gas recovery scaling law can be captured well by continuum models in which the gas adsorption and desorption from pore walls are taken into account using the Langmuir model.

  3. Computational and experimental study of nanoporous membranes for water desalination and decontamination.

    Energy Technology Data Exchange (ETDEWEB)

    Hickner, Michael A. (Penn State University, University Park, PA); Chinn, Douglas Alan (Sandia National Laboratories, Albuquerque, NM); Adalsteinsson, Helgi; Long, Kevin R. (Texas Tech University, Lubbock, TX); Kent, Michael Stuart (Sandia National Laboratories, Albuquerque, NM); Debusschere, Bert J.; Zendejas, Frank J.; Tran, Huu M.; Najm, Habib N.; Simmons, Blake Alexander

    2008-11-01

    Fundamentals of ion transport in nanopores were studied through a joint experimental and computational effort. The study evaluated both nanoporous polymer membranes and track-etched nanoporous polycarbonate membranes. The track-etched membranes provide a geometrically well characterized platform, while the polymer membranes are more closely related to ion exchange systems currently deployed in RO and ED applications. The experimental effort explored transport properties of the different membrane materials. Poly(aniline) membranes showed that flux could be controlled by templating with molecules of defined size. Track-etched polycarbonate membranes were modified using oxygen plasma treatments, UV-ozone exposure, and UV-ozone with thermal grafting, providing an avenue to functionalized membranes, increased wettability, and improved surface characteristic lifetimes. The modeling effort resulted in a novel multiphysics multiscale simulation model for field-driven transport in nanopores. This model was applied to a parametric study of the effects of pore charge and field strength on ion transport and charge exclusion in a nanopore representative of a track-etched polycarbonate membrane. The goal of this research was to uncover the factors that control the flux of ions through a nanoporous material and to develop tools and capabilities for further studies. Continuation studies will build toward more specific applications, such as polymers with attached sulfonate groups, and complex modeling methods and geometries.

  4. Manipulation of Protein Translocation through Nanopores by Flow Field Control and Application to Nanopore Sensors.

    Science.gov (United States)

    Hsu, Wei-Lun; Daiguji, Hirofumi

    2016-09-20

    The control of biomolecule translocation through nanopores is important in nanopore protein detection. Improvement in current nanopore molecule control is desired to enhance capture rates, extend translocation times, and ensure the effective detection of various proteins in the same solutions. We present a method that simultaneously resolves these issues through the use of a gate-modulated conical nanopore coupled with solutions of varying salt concentration. Simulation results show that the presence of an induced reverse electroosmotic flow (IREOF) results in inlet flows from the two ends of the nanopore centerline entering into the nanopore in opposite directions, which simultaneously elevates the capture rate and immobilizes the protein in the nanopore, thus enabling steady current blockage measurements for a range of proteins. In addition, it is shown that proteins with different size/charge ratios can be trapped by a gate modulation intensified flow field at a similar location in the nanopore in the same solution conditions.

  5. Molecular release from patterned nanoporous gold thin films

    Science.gov (United States)

    Kurtulus, Ozge; Daggumati, Pallavi; Seker, Erkin

    2014-05-01

    Nanostructured materials have shown significant potential for biomedical applications that require high loading capacity and controlled release of drugs. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a promising novel material that benefits from compatibility with microfabrication, tunable pore morphology, electrical conductivity, well-established gold-thiol conjugate chemistry, and biocompatibility. While np-Au's non-biological applications are abundant, its performance in the biomedical field is nascent. In this work, we employ a combination of techniques including nanoporous thin film synthesis, quantitative electron microscopy, fluorospectrometry, and electrochemical surface characterization to study loading capacity and molecular release kinetics as a function of film properties and discuss underlying mechanisms. The sub-micron-thick sputter-coated nanoporous gold films provide small-molecule loading capacities up to 1.12 μg cm-2 and molecular release half-lives between 3.6 hours to 12.8 hours. A systematic set of studies reveals that effective surface area of the np-Au thin films on glass substrates plays the largest role in determining loading capacity. The release kinetics on the other hand depends on a complex interplay of micro- and nano-scale morphological features.Nanostructured materials have shown significant potential for biomedical applications that require high loading capacity and controlled release of drugs. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a promising novel material that benefits from compatibility with microfabrication, tunable pore morphology, electrical conductivity, well-established gold-thiol conjugate chemistry, and biocompatibility. While np-Au's non-biological applications are abundant, its performance in the biomedical field is nascent. In this work, we employ a combination of techniques including nanoporous thin film synthesis, quantitative electron microscopy

  6. Flexible 3D Nanoporous Graphene for Desalination and Bio-decontamination of Brackish Water via Asymmetric Capacitive Deionization

    NARCIS (Netherlands)

    El-Deen, Ahmed G.; Boom, Remko M.; Kim, Hak Yong; Duan, Hongwei; Chan-Park, Mary B.; Choi, Jae Hwan

    2016-01-01

    Nanoporous graphene based materials are a promising nanostructured carbon for energy storage and electrosorption applications. We present a novel and facile strategy for fabrication of asymmetrically functionalized microporous activated graphene electrodes for high performance capacitive desalinatio

  7. Flexible 3D Nanoporous Graphene for Desalination and Bio-decontamination of Brackish Water via Asymmetric Capacitive Deionization

    NARCIS (Netherlands)

    El-Deen, Ahmed G.; Boom, Remko M.; Kim, Hak Yong; Duan, Hongwei; Chan-Park, Mary B.; Choi, Jae Hwan

    2016-01-01

    Nanoporous graphene based materials are a promising nanostructured carbon for energy storage and electrosorption applications. We present a novel and facile strategy for fabrication of asymmetrically functionalized microporous activated graphene electrodes for high performance capacitive

  8. Giant Osmotic Pressure in the Forced Wetting of Hydrophobic Nanopores.

    Science.gov (United States)

    Michelin-Jamois, Millan; Picard, Cyril; Vigier, Gérard; Charlaix, Elisabeth

    2015-07-17

    The forced intrusion of water in hydrophobic nanoporous pulverulent material is of interest for quick storage of energy. With nanometric pores the energy storage capacity is controlled by interfacial phenomena. With subnanometric pores, we demonstrate that a breakdown occurs with the emergence of molecular exclusion as a leading contribution. This bulk exclusion effect leads to an osmotic contribution to the pressure that can reach levels never previously sustained. We illustrate, on various electrolytes and different microporous materials, that a simple osmotic pressure law accounts quantitatively for the enhancement of the intrusion and extrusion pressures governing the forced wetting and spontaneous drying of the nanopores. Using electrolyte solutions, energy storage and power capacities can be widely enhanced.

  9. Nanoporous Aluminium Oxide Membranes as Cell Interfaces

    Directory of Open Access Journals (Sweden)

    Dorothea Brüggemann

    2013-01-01

    Full Text Available Nanoporous anodic aluminium oxide (AAO has become increasingly important in biomedical applications over the past years due to its biocompatibility, increased surface area, and the possibility to tailor this nanomaterial with a wide range of surface modifications. AAO nanopores are formed in an inexpensive anodisation process of pure aluminium, which results in the self-assembly of highly ordered, vertical nanochannels with well-controllable pore diameters, depths, and interpore distances. Because of these outstanding properties AAO nanopores have become excellent candidates as nanostructured substrates for cell-interface studies. In this comprehensive review previous surveys on cell adhesion and proliferation on different AAO nanopore geometries and surface modifications are highlighted and summarised tabularly. Future applications of nanoporous alumina membranes in biotechnology and medicine are also outlined, for instance, the use of nanoporous AAO as implant modifications, coculture substrates, or immunoisolation devices.

  10. 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.

  11. 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.

  12. Bimetallic Metal-Organic Frameworks for Controlled Catalytic Graphitization of Nanoporous Carbons

    Science.gov (United States)

    Tang, Jing; Salunkhe, Rahul R.; Zhang, Huabin; Malgras, Victor; Ahamad, Tansir; Alshehri, Saad M.; Kobayashi, Naoya; Tominaka, Satoshi; Ide, Yusuke; Kim, Jung Ho; Yamauchi, Yusuke

    2016-07-01

    Single metal-organic frameworks (MOFs), constructed from the coordination between one-fold metal ions and organic linkers, show limited functionalities when used as precursors for nanoporous carbon materials. Herein, we propose to merge the advantages of zinc and cobalt metals ions into one single MOF crystal (i.e., bimetallic MOFs). The organic linkers that coordinate with cobalt ions tend to yield graphitic carbons after carbonization, unlike those bridging with zinc ions, due to the controlled catalytic graphitization by the cobalt nanoparticles. In this work, we demonstrate a feasible method to achieve nanoporous carbon materials with tailored properties, including specific surface area, pore size distribution, degree of graphitization, and content of heteroatoms. The bimetallic-MOF-derived nanoporous carbon are systematically characterized, highlighting the importance of precisely controlling the properties of the carbon materials. This can be done by finely tuning the components in the bimetallic MOF precursors, and thus designing optimal carbon materials for specific applications.

  13. Nanopore analytics: sensing of single molecules.

    Science.gov (United States)

    Howorka, Stefan; Siwy, Zuzanna

    2009-08-01

    In nanopore analytics, individual molecules pass through a single nanopore giving rise to detectable temporary blockades in ionic pore current. Reflecting its simplicity, nanopore analytics has gained popularity and can be conducted with natural protein as well as man-made polymeric and inorganic pores. The spectrum of detectable analytes ranges from nucleic acids, peptides, proteins, and biomolecular complexes to organic polymers and small molecules. Apart from being an analytical tool, nanopores have developed into a general platform technology to investigate the biophysics, physicochemistry, and chemistry of individual molecules (critical review, 310 references).

  14. New approach to fabricate nanoporous gold film

    Institute of Scientific and Technical Information of China (English)

    Hui Zhou; Lan Jin; Wei Xu

    2007-01-01

    A simple preparation of ultrathin nanoporous gold film was described. Copper and gold were used to fabricate Cu-Au alloy films through vacuum deposition. The formation of nanoporous gold films from the alloy films involved thermal process and chemical etch by hydrochloric acid or by nitric acid. The free-standing nanoporous gold films have been analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS) and surface-enhanced Raman scattering (SERS). It was noted that the nanoporous gold film etched by hydrochloric acid is uniform with a cover of fog-like moieties.

  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......-sided skin membranes, much faster than expected by a naive resistance-in-series model; the flux through the two-sided skin membranes even increases with the membrane thickness. We propose a model that captures the physics behind the observed phenomena, as confirmed by flow visualization experiments...... the effective diffusion coefficients of a series of antibiotics, proteins, and other biomolecules; solute permeation is discussed in terms of hindered diffusion. The combination of uniform bulk morphology, isotropically percolating porosity, controlled surface chemistry, and tunable permeability is distinctive...

  16. Multilayer Nanoporous Graphene Membranes for Water Desalination.

    Science.gov (United States)

    Cohen-Tanugi, David; Lin, Li-Chiang; Grossman, Jeffrey C

    2016-02-10

    While single-layer nanoporous graphene (NPG) has shown promise as a reverse osmosis (RO) desalination membrane, multilayer graphene membranes can be synthesized more economically than the single-layer material. In this work, we build upon the knowledge gained to date toward single-layer graphene to explore how multilayer NPG might serve as a RO membrane in water desalination using classical molecular dynamic simulations. We show that, while multilayer NPG exhibits similarly promising desalination properties to single-layer membranes, their separation performance can be designed by manipulating various configurational variables in the multilayer case. This work establishes an atomic-level understanding of the effects of additional NPG layers, layer separation, and pore alignment on desalination performance, providing useful guidelines for the design of multilayer NPG membranes.

  17. Optical characteristics of wet-thermally oxidized bulk and nanoporous GaN

    Science.gov (United States)

    Kim, Sinjae; Kadam, Mahadev; Kang, Jin-Ho; Ryu, Sang-Wan

    2016-09-01

    Gallium nitride (GaN) films deposited on sapphire substrates by metal organic chemical vapor deposition were successfully transformed into bulk and nanoporous gallium oxide (Ga2O3) using a wet thermal oxidation technique. Oxidation depth measurements confirmed that the oxide growth appeared to be faster in the case of nanoporous GaN than that of bulk GaN. Spectroscopic ellipsometry was used to evaluate and compare the optical properties of nanoporous and bulk Ga2O3 films, such as refractive index and extinction coefficient, which revealed improved optical properties for nanoporous Ga2O3 compared to the bulk. The simulations conducted on the ellipsometric spectra for bulk and nanoporous Ga2O3 using the Forouhi-Bloomer model and the Bruggeman effective medium approximation revealed the best fit with a low mean square error value. In the case of nanoporous Ga2O3, zero absorption was observed in the wavelength range of 300 nm to 840 nm, supporting the use of this material as a transparent coating in optoelectronic devices.

  18. 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

    2017-01-01

    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. PMID:28252106

  19. 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

    2017-03-01

    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.

  20. High Performance Optical Coatings Utilizing Tailored Refractive Index Nanoporous Thin Films

    Science.gov (United States)

    Poxson, David J.

    Refractive index is perhaps the most important quantity in optics. It is particularly relevant in the field of optical coatings, where the refractive index appears in virtually every optics equation as a figure of merit. Recently it has been demonstrated through control of the deposition angle during oblique-angle electron-beam deposition, nanoporous films of virtually any desired porosity may be accurately deposited. As the porosity of a nanoporous film directly relates to its effective refractive index, the refractive index value of a film may be tailored to any value between that of the bulk material and close to that of air. These two characteristics, namely; (i) tailored-refractive index and (ii) very low-refractive index values close to that of air, offer significant advantages in the design and optical performance in all optical coating applications. In this dissertation we explore optical coating applications whose performance can be greatly enhanced by utilization of a tailored- and low-refractive index nanoporous material system. One such important application is in the design and fabrication of broadband, omnidirectional antireflection (AR) coatings on solar cell devices. To harness the full spectrum of solar energy, Fresnel reflections at the surface of a photovoltaic cell must be reduced as much as possible over the relevant solar wavelength range and over a wide range of incident angles. However, the development of AR coatings embodying omni-directionality over a wide range of wavelengths is challenging. By utilizing the tailored- and low-refractive index properties of the nanoporous material system, in conjunction with a computational genetic algorithm and a predictive quantitative model for the porosity of such nanoporous films, truly optimized AR coatings can be designed and fabricated on solar cells. Here we show that these optimized AR structures demonstrate significant improvement to overall device efficiency. Traditionally, nanoporous films

  1. Surface Chemistry in Nanoscale Materials

    Directory of Open Access Journals (Sweden)

    Alex V. Hamza

    2009-12-01

    Full Text Available Although surfaces or, more precisely, the surface atomic and electronic structure, determine the way materials interact with their environment, the influence of surface chemistry on the bulk of the material is generally considered to be small. However, in the case of high surface area materials such as nanoporous solids, surface properties can start to dominate the overall material behavior. This allows one to create new materials with physical and chemical properties that are no longer determined by the bulk material, but by their nanoscale architectures. Here, we discuss several examples, ranging from nanoporous gold to surface engineered carbon aerogels that demonstrate the tuneability of nanoporous solids for sustainable energy applications.

  2. Effect of ultraviolet illumination and ambient gases on the photoluminescence and electrical properties of nanoporous silicon layer for organic vapor sensor.

    Science.gov (United States)

    Atiwongsangthong, Narin

    2012-08-01

    The purpose of this research, the nanoporous silicon layer were fabricated and investigated the physical properties such as photoluminescence and the electrical properties in order to develop organic vapor sensor by using nanoporous silicon. The Changes in the photoluminescence intensity of nanoporous silicon samples are studied during ultraviolet illumination in various ambient gases such as nitrogen, oxigen and vacuum. In this paper, the nanoporous silicon layer was used as organic vapor adsorption and sensing element. The advantage of this device are simple process compatible in silicon technology and usable in room temperature. The structure of this device consists of nanoporous silicon layer which is formed by anodization of silicon wafer in hydrofluoric acid solution and aluminum electrode which deposited on the top of nanoporous silicon layer by evaporator. The nanoporous silicon sensors were placed in a gas chamber with various organic vapor such as ethanol, methanol and isopropyl alcohol. From studying on electrical characteristics of this device, it is found that the nanoporous silicon layer can detect the different organic vapor. Therefore, the nanoporous silicon is important material for organic vapor sensor and it can develop to other applications about gas sensors in the future.

  3. Ion selectivity of graphene nanopores

    OpenAIRE

    Rollings, Ryan C.; Kuan, Aaron T.; Golovchenko, Jene A.

    2016-01-01

    As population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores prefer...

  4. Type and distribution of chemical groups from controlled photo-oxidation of gyroid nanoporous 1,2-polybutadiene

    DEFF Research Database (Denmark)

    Sagar, Kaushal Shashikant; Christiansen, Mads Brøkner; Ndoni, Sokol

    2011-01-01

    Photo-oxidation of nanoporous polymers is little studied. The high UV penetration depth and high surface concentration in these materials give unprecedented possibilities both in fundamental work on surface photochemistry and in nanotechnological applications related for example to patterned...... hydrophilicity or refractive index. This is a quantitative study of the photo-oxidation products of nanoporous gyroid 1,2-polybutadiene in air. Irradiation of the porous sample with UV in the wavelength range of 300–400nm enables tuning of the hydrophilicity of the nanoporous polymer through formation...

  5. Lattice thermal conductivity diminution and high thermoelectric power factor retention in nanoporous macroassemblies of sulfur-doped bismuth telluride nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanliang; Mehta, Rutvik J.; Belley, Matthew; Han, Liang; Ramanath, Ganpati; Borca-Tasciuc, Theodorian

    2012-01-01

    We report ultralow lattice thermal conductivity in the 0.3 ≤ κL ≤ 0.6 W m⁻¹ K⁻¹ range in nanoporous bulk bismuth telluride pellets obtained by sintering chemically synthesized nanostructures, together with single-crystal-like electron mobilities and Seebeck coefficients at comparable charge carrier concentrations. The observed κL is up to 35% lower than classical effective medium predictions, and can be quantitatively explained by increased phonon scattering at nanopores and nanograins. Our findings are germane to tailoring nanoporous thermoelectric materials for efficient solid-state refrigeration, thermal energy harvesting, and thermal management applications.

  6. Interface elasticity effects in polymer-filled nanoporous metals

    Science.gov (United States)

    Wilmers, J.; McBride, A.; Bargmann, S.

    2017-02-01

    A continuum formulation for electroactive composites made from nanoporous gold and ion-conducting polymer is proposed. A novel extension of surface elasticity theory is developed to account for the high surface-to-volume ratio of nanoporous gold, and to capture the chemoelectromechanical coupling that occurs on the interface between the metal and the polymer. This continuum formulation accounts for the fully non-linear behaviour exhibited by the composite. The balance of linear momentum, Gauß's flux theorem and a relation for the transport of charge carriers are introduced in the bulk material as well as on the interface to describe the non-linear multiphysics and highly coupled response of the actuator. The resulting system of non-linear equations is solved using the finite element method. A series of numerical examples is presented to elucidate the theory.

  7. Water and Molecular Transport across Nanopores in Monolayer Graphene Membranes

    Science.gov (United States)

    Jang, Doojoon; O'Hern, Sean; Kidambi, Piran; Boutilier, Michael; Song, Yi; Idrobo, Juan-Carlos; Kong, Jing; Laoui, Tahar; Karnik, Rohit

    2015-11-01

    Graphene's atomic thickness and high tensile strength allow it to outstand as backbone material for next-generation high flux separation membrane. Molecular dynamics simulations predicted that a single-layer graphene membrane could exhibit high permeability and selectivity for water over ions/molecules, qualifying as novel water desalination membranes. However, experimental investigation of water and molecular transport across graphene nanopores had remained barely explored due to the presence of intrinsic defects and tears in graphene. We introduce two-step methods to seal leakage across centimeter scale single-layer graphene membranes create sub-nanometer pores using ion irradiation and oxidative etching. Pore creation parameters were varied to explore the effects of created pore structures on water and molecular transport driven by forward osmosis. The results demonstrate the potential of nanoporous graphene as a reliable platform for high flux nanofiltration membranes.

  8. Molecular diagnostics for personal medicine using a nanopore.

    Science.gov (United States)

    Mirsaidov, Utkur M; Wang, Deqiang; Timp, Winston; Timp, Gregory

    2010-01-01

    Semiconductor nanotechnology has created the ultimate analytical tool: a nanopore with single molecule sensitivity. This tool offers the intriguing possibility of high-throughput, low cost sequencing of DNA with the absolute minimum of material and preprocessing. The exquisite single molecule sensitivity obviates the need for costly and error-prone procedures like polymerase chain reaction amplification. Instead, nanopore sequencing relies on the electric signal that develops when a DNA molecule translocates through a pore in a membrane. If each base pair has a characteristic electrical signature, then ostensibly a pore could be used to analyze the sequence by reporting all of the signatures in a single read without resorting to multiple DNA copies. The potential for a long read length combined with high translocation velocity should make resequencing inexpensive and allow for haplotyping and methylation profiling in a chromosome.

  9. 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.

  10. 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

  11. Method to fabricate functionalized conical nanopores

    Science.gov (United States)

    Small, Leo J.; Spoerke, Erik David; Wheeler, David R.

    2016-07-12

    A pressure-based chemical etch method is used to shape polymer nanopores into cones. By varying the pressure, the pore tip diameter can be controlled, while the pore base diameter is largely unaffected. The method provides an easy, low-cost approach for conically etching high density nanopores.

  12. 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...

  13. 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 provide

  14. Reconstructing solid state nanopore shape from electrical measurements

    Science.gov (United States)

    Liebes, Yael; Drozdov, Maria; Avital, Yotam Y.; Kauffmann, Yaron; Rapaport, Hanna; Kaplan, Wayne D.; Ashkenasy, Nurit

    2010-11-01

    The dependence of nanopore biosensor conductance signal on the nanopore shape makes it important to decipher the latter with high precision. We show here that the three dimensional shape of a nanopore, extracted from electron microscopy analysis, allows for modeling the conductance of the nanopore over a wide range of ionic strengths. Furthermore, we demonstrate that the dependence of the nanopore conductance on ionic strength can be used to accurately extract the nanopore shape, eliminating the need for lengthy electron microscopy analysis. The suggested methodology can be used to monitor changes in the nanopore shape and evaluate them during electrical characterization.

  15. Nanopore DNA sequencing using kinetic proofreading

    Science.gov (United States)

    Ling, Xinsheng

    We propose a method of DNA sequencing by combining the physical method of nanopore electrical measurements and Southern's sequencing-by-hybridization. The new key ingredient, essential to both lowering the costs and increasing the precision, is an asymmetric nanopore sandwich device capable of measuring the DNA hybridization probe twice separated by a designed waiting time. Those incorrect probes appearing only once in nanopore ionic current traces are discriminated from the correct ones that appear twice. This method of discrimination is similar to the principle of kinetic proofreading proposed by Hopfield and Ninio in gene transcription and translation processes. An error analysis is of this nanopore kinetic proofreading (nKP) technique for DNA sequencing is carried out in comparison with the most precise 3' dideoxy termination method developed by Sanger. Nanopore DNA sequencing using kinetic proofreading.

  16. 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.

  17. Understanding Energy Absorption Behaviors of Nanoporous Materials

    Science.gov (United States)

    2008-05-23

    a mesoporous silica. Microporous Mesoporous Mater. 103, 35-39 (2007). 15. Han, A.; Qiao, Y. Suppression effect of liquid composition on...defiltration of nanofluids in lyophobic environment. J. Phys. D – Appl. Phys. 40, 3436-3439. 16. Punyamurtula, V. K.; Qiao, Y. Hysteresis of sorption isotherm...3 (2005). 32. Kong, X., Surani, F. B., and Qiao, Y. Effects of addition of chemical admixtures on the infiltration pressure of a mesoporous silica

  18. IMPROVED CATALYSTS FOR HEAVY OIL UPGRADING BASED ON ZEOLITE Y NANOPARTICLES ENCAPSULATED STABLE NANOPOROUS HOST

    Energy Technology Data Exchange (ETDEWEB)

    Conrad Ingram; Mark Mitchell

    2005-03-21

    The objectives of this project are to synthesis nanocrystals of highly acidic zeolite Y, 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. Our results to date are summarized as follows. The synthesis of high surface ordered nanoporous silica of expanded pore diameter of 25 nm (larger than the standard size of 8.4 nm) using trimethylbenzene as a pore size expander was accomplished. The synthesis of zeolite Y nanoparticles with median pore size of approximately 50 nm (smaller than the 80 nm typically obtained with TMAOH) using combined TMABr/TMAOH as organic additives was also accomplished. The successful synthesis of zeoliteY/Nanoporous host composite materials by sequential combination of zeolite precursors and nanoporous material precursor mixtures was implied based on results from various characterization techniques such as X-Ray diffraction, infrared spectra, thermal analysis, porosimetry data. The resulting materials showed pore sizes up to 11 nm, and infrared band at 570 cm{sup -1} suggesting the presence of both phases. Work in the immediate future will be focused on the following three areas: (1) Further characterization of all-silica and aluminosilicate mesoporous materials with expanded pore sizes up to 30 nm will continue; (2) Research efforts to reduce the average particle size of zeolite nanoparticles down to 35-30 nm will continue; (3) Further synthesis of polymer-SBA15 nanocomposites will be conducted by changing the amount and chemistry of the zeolitic precursors added; and (4) Investigation on the catalytic properties of the materials using probe catalytic reactions (such as cumene cracking), followed by catalytic testing for heavy oil conversion.

  19. Effect of annealing temperature on electrochemical luminescence properties of nanoporous fluorine-doped tin oxide films.

    Science.gov (United States)

    Joo, Bong-Hyun; Yoon, Seog-Young; Sung, Youl-Moon

    2013-04-01

    Nanoporous Fluorine-doped tin oxide (FTO) materials were synthesized by sol-gel combustion method for electrochemical luminescence (ECL) application. The influence of annealing temperature on the structures and morphology of the nanoporous FTO films was examined by X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmittance and BET specific surface measurements. The naoporous FTO-based ECL cell is composed of FTO glass/nanoporous FTO/Ru(bpy)2+ electrolyte/FTO glass. The peak intensity of emitting light from the cell was obtained at the wavelength of about 615 nm, which corresponds to dark orange color. At 5 V bias, ECL efficiency of the cell using the 550 degrees C annealed FTO was about 975 cd/m2, which is much higher than those of other cells. The result shows that the nanoporous FTO layer was more effective for increasing ECL intensities. The sol-gel combustion method at annealing temperature of 550 degrees C could be employed to synthesize the nanoporous FTO materials with high porosity and ECL performance.

  20. Terahertz and mid-infrared plasmons in three-dimensional nanoporous graphene

    Science.gov (United States)

    D'Apuzzo, Fausto; Piacenti, Alba R.; Giorgianni, Flavio; Autore, Marta; Guidi, Mariangela Cestelli; Marcelli, Augusto; Schade, Ulrich; Ito, Yoshikazu; Chen, Mingwei; Lupi, Stefano

    2017-01-01

    Two-dimensional (2D) graphene emerged as an outstanding material for plasmonic and photonic applications due to its charge-density tunability, high electron mobility, optical transparency and mechanical flexibility. Recently, novel fabrication processes have realised a three-dimensional (3D) nanoporous configuration of high-quality monolayer graphene which provides a third dimension to this material. In this work, we investigate the optical behaviour of nanoporous graphene by means of terahertz and infrared spectroscopy. We reveal the presence of intrinsic 2D Dirac plasmons in 3D nanoporous graphene disclosing strong plasmonic absorptions tunable from terahertz to mid-infrared via controllable doping level and porosity. In the far-field the spectral width of these absorptions is large enough to cover most of the mid-Infrared fingerprint region with a single plasmon excitation. The enhanced surface area of nanoporous structures combined with their broad band plasmon absorption could pave the way for novel and competitive nanoporous-graphene based plasmonic-sensors. PMID:28345584

  1. Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media.

    Science.gov (United States)

    Huber, Patrick

    2015-03-18

    Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications. A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.

  2. Detection of long and short DNA using nanopores with graphitic polyhedral edges.

    Science.gov (United States)

    Freedman, Kevin J; Ahn, Chi Won; Kim, Min Jun

    2013-06-25

    Graphene is a unique material with a thickness as low as a single atom, high in-plane conductivity and a robust lattice that is self-supporting over large length scales. Schematically, graphene is an ideal solid-state material for tuning the properties of a nanopore because self-supported sheets, ranging from single to multiple atomic layers, can create pores with near-arbitrary dimensions which can provide exquisite control of the electric field drop within the pore. In this study, we characterize the drilling kinetics of nanopores using a thermionic electron source and various electron beam fluxes to minimize secondary hole formation. Once established, we investigated the use of multilayer graphene to create highly tailored nanostructures including nanopores with graphite polyhedral crystals formed around the nanopore edge. Finally, we report on the translocation of double stranded and single stranded DNA through such graphene pores and show that the single stranded DNA translocates much slower allowing detection of extremely short fragments (25 nucleotides in length). Our findings suggest that the kinetic and controllable properties of graphene nanopores under sculpting conditions can be used to further enhance the detection of DNA analytes.

  3. Protein interactions with nanoporous sol-gel derived bioactive glasses.

    Science.gov (United States)

    Lin, Sen; Van den Bergh, Wouter; Baker, Simon; Jones, Julian R

    2011-10-01

    Sol-gel derived bioactive glasses are excellent candidates for bone regenerative implant materials as they bond with bone, stimulate bone growth and degrade in the body. Their interactions with proteins are critical to understanding their performance after implantation. This study focuses on the interactions between fibrinogen and sol-gel glass particles of the 70S30C (70 mol.% SiO(2), 30 mol.% CaO composition). Sol-gel silica and melt-derived Bioglass® were also used for comparison. Fibrinogen penetration into the nanoporous glasses was observed by live tracking the fluorescent-labelled fibrinogen with confocal microscopy. The effect of pore size on protein penetration was investigated. Nanoporous networks with modal pore diameters larger than 6 nm were accessible to fibrinogen. When the modal nanopore diameter was decreased to 2 nm or less, the penetration of fibrinogen was inhibited. The surface properties of the glasses, which can be modulated by media pH, glass composition and final stabilisation temperature in the sol-gel process, have effects on fibrinogen adsorption via long-range Coulombic forces before the adsorption and via short-range interactions such as hydrogen bonding after the adsorption.

  4. Bulk synthesis of nanoporous palladium and platinum powders

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, David B; Fares, Stephen J; Tran, Kim L; Langham, Mary E

    2014-04-15

    Disclosed is a method for providing nanoporous palladium and platinum powders. These materials were synthesized on milligram to gram scales by chemical reduction of tetrahalo-complexes with ascorbate in a concentrated aqueous surfactant at temperatures between -20.degree. C. and 30.degree. C. The prepared particles have diameters of approximately 50 nm, wherein each particle is perforated by pores having diameters of approximately 3 nm, as determined by electron tomography. These materials are of potential value for hydrogen and electrical charge storage applications.

  5. 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.

  6. Bulk synthesis of nanoporous palladium and platinum powders

    Science.gov (United States)

    Robinson, David B [Fremont, CA; Fares, Stephen J [Pleasanton, CA; Tran, Kim L [Livermore, CA; Langham, Mary E [Pleasanton, CA

    2012-04-17

    Disclosed is a method for providing nanoporous palladium and platinum powders. These materials were synthesized on milligram to gram scales by chemical reduction of tetrahalo-complexes with ascorbate in a concentrated aqueous surfactant at temperatures between -20.degree. C. and 30.degree. C. The prepared particles have diameters of approximately 50 nm, wherein each particle is perforated by pores having diameters of approximately 3 nm, as determined by electron tomography. These materials are of potential value for hydrogen and electrical charge storage applications.

  7. 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.

  8. IMPROVED CATALYSTS FOR HEAVY OIL UPGRADING BASED ON ZEOLITE Y NANOPARTICLES ENCAPSULATED IN STABLE NANOPOROUS HOST

    Energy Technology Data Exchange (ETDEWEB)

    Conrad Ingram; Mark Mitchell

    2005-03-31

    The objectives of this project are to synthesis nanocrystals of highly acidic zeolite Y, 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. Our results to date are summarized as follows. The synthesis of high surface ordered nanoporous silica of expanded pore diameter of 25 nm (larger than the standard size of 8.4 nm) using trimethylbenzene as a pore size expander was accomplished. The synthesis of zeolite Y nanoparticles with median pore size of approximately 50 nm (smaller than the 80 nm typically obtained with TMAOH) using combined TMABr/TMAOH as organic additives was also accomplished. The successful synthesis of zeoliteY/Nanoporous host composite materials by sequential combination of zeolite precursors and nanoporous material precursor mixtures was implied based on results from various characterization techniques such as X-Ray diffraction, infrared spectra, thermal analysis, porosimetry data. The resulting materials showed pore sizes up to 11 nm, and infrared band at 570 cm{sup -1} suggesting the presence of both phases. New results indicated that good quality highly ordered nanoporous silica host can be synthesized in the presence of zeolite Y seed precursor depending on the amount of precursor added. Preliminary research on the catalytic performance of the materials is underway. Probe acid catalyzed reactions, such as the cracking of cumene is currently being conducted. Work in the immediate future will be focused on the following three areas: (1) Further characterization of all-silica and aluminosilicate mesoporous materials with expanded pore sizes up to 30 nm will continue; (2) Research efforts to reduce the average particle size of zeolite nanoparticles down to 35-30 nm will continue; (3) Further synthesis of ZeoliteY/Nanoporous host composite catalysts of

  9. Water behaviour in nanoporous aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Konstantin S; Bougeard, Daniel, E-mail: Konstantin.Smirnov@univ-lille1.f [Laboratoire de Spectrochimie Infrarouge et Raman, Universite Lille 1, Sciences et Technologie, CNRS, Batiment C5, 59655 Villeneuve d' Ascq (France)

    2010-07-21

    This paper briefly reviews results of molecular dynamics simulation studies of water confined in nanoporous aluminosilicates. The behaviour of confined molecules is shown to be influenced by the nature of the host structure, and the size and the topology of the voids. For some of the systems discussed the ambiguity in results of different modelling studies call for the use of extended potential and structural models. Thus, the use of polarizable force fields was shown to be necessary to take into account the variation of the molecular dipole of confined molecules in different environments.

  10. Fracture and fatigue of ultrathin nanoporous polymer films

    Science.gov (United States)

    Kearney, Andrew V.

    Nanoporous polymer layers are being considered for a range of emerging nanoscale applications, from low permittivity materials for interlayer dielectrics in microelectronics and anti-reflective coatings in optical technologies, to biosensors and size-selective membranes for biological applications. Polymer thin films have inherently low elastic modulus, strength and hardness, but exhibit fracture properties that are higher than those reported for glass, ceramic, and even some metal layers. However, constraint of a ductile polymer between two elastic layers is expected to affect the local plasticity ahead of a crack tip and its contribution to the film adhesion with films below a micron in thickness. Additionally, nanoporosity would be expected to have a deleterious effect on mechanical properties, producing materials and layers that are structurally weaker than fully dense versions they replace. Therefore, the integration of these nanoporous polymer layer at nanometer thicknesses would present significantly processing and mechanical reliability challenges. In this dissertation, surprising evidence is presented that nanoporous polymer films exhibit increasing fracture energy with increasing porosity. Such behavior is in stark contrast to a wide range of reported behavior for porous solids. A ductile nano-void growth and coalescence fracture mechanics-based model is presented to rationalize the increase in fracture toughness of the voided polymer film. The model is shown to explain the behavior in terms of a specific scaling of the size of the pores with pore volume fraction. It is demonstrated that the pore size must increase with close to a linear dependence on the volume fraction in order to increase rather than decrease the fracture energy. Independent characterization of the pore size as a function of volume fraction is shown to confirm predictions made by the model. The fracture behavior of these constrained polymer films are also examined with film thickness

  11. DNA origami nanopores for controlling DNA translocation.

    Science.gov (United States)

    Hernández-Ainsa, Silvia; Bell, Nicholas A W; Thacker, Vivek V; Göpfrich, Kerstin; Misiunas, Karolis; Fuentes-Perez, Maria Eugenia; Moreno-Herrero, Fernando; Keyser, Ulrich F

    2013-07-23

    We combine DNA origami structures with glass nanocapillaries to reversibly form hybrid DNA origami nanopores. Trapping of the DNA origami onto the nanocapillary is proven by imaging fluorescently labeled DNA origami structures and simultaneous ionic current measurements of the trapping events. We then show two applications highlighting the versatility of these DNA origami nanopores. First, by tuning the pore size we can control the folding of dsDNA molecules ("physical control"). Second, we show that the specific introduction of binding sites in the DNA origami nanopore allows selective detection of ssDNA as a function of the DNA sequence ("chemical control").

  12. 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...

  13. Generation of nanopores during desorption of NH3 from Mg(NH3)6Cl2

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Sørensen, Rasmus Zink; Kostova, M.Y.;

    2006-01-01

    It is shown that nanopores are formed during desorption of NH3 from Mg(NH3)6Cl2, which has been proposed as a hydrogen storage material. The system of nanopores facilitates the transport of desorbed ammonia away from the interior of large volumes of compacted storage material. DFT calculations show...... that there exists a continuous path from the initial Mg(NH3)6Cl2 material to MgCl2 that does not involve large-scale material transport. Accordingly, ammonia desorption from this system is facile....

  14. Ordering and defects in self-assembled monolayers on nanoporous gold

    Science.gov (United States)

    Patel, Dipna A.; Weller, Andrew M.; Chevalier, Robert B.; Karos, Constantine A.; Landis, Elizabeth C.

    2016-11-01

    Self-assembled monolayers are commonly used to tailor nanoporous structures for applications, and they also provide a model system for determining the effects of nanoscale structure on self-assembly. We have investigated the ordering and defects in alkanethiol self-assembled monolayers on nanoporous gold, a high surface area mesoporous material. Infrared reflection absorption spectroscopy was used to characterize the effects of alkyl chain length and nanoporous gold pore size on molecular layer ordering. Cyclic voltammetry was used to characterize the monolayer density and ordering, with ferrocenylalkylthiolates used to quantify and characterize defect sites. We find that dense and well-ordered molecular layers form quickly with low defect levels. However, we do not observe differences in molecular layer ordering or defects with changes in pore size.

  15. 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.

  16. Nanoporous Polymer Films of Cyanate Ester Resins Designed by Using Ionic Liquids as Porogens

    Science.gov (United States)

    Fainleib, Alexander; Vashchuk, Alina; Starostenko, Olga; Grigoryeva, Olga; Rogalsky, Sergiy; Nguyen, Thi-Thanh-Tam; Grande, Daniel

    2017-02-01

    Novel nanoporous film materials of thermostable cyanate ester resins (CERs) were generated by polycyclotrimerization of dicyanate ester of bisphenol E in the presence of varying amounts (from 20 to 40 wt%) of an ionic liquid (IL), i.e., 1-heptylpyridinium tetrafluoroborate, followed by its quantitative extraction after complete CER network formation. The completion of CER formation and IL extraction was assessed using gel fraction content determination, FTIR, 1H NMR, and energy-dispersive X-ray spectroscopy (EDX). SEM and DSC-based thermoporometry analyses demonstrated the formation of nanoporous structures after IL removal from CER networks, thus showing the effective role of IL as a porogen. Pore sizes varied from 20 to 180 nm with an average pore diameter of around 45-60 nm depending on the initial IL content. The thermal stability of nanoporous CER-based films was investigated by thermogravimetric analysis.

  17. Microtome Sliced Block Copolymers and Nanoporous Polymers as Masks for Nanolithography

    DEFF Research Database (Denmark)

    Shvets, Violetta; Schulte, Lars; Ndoni, Sokol

    2014-01-01

    -linked phase are sliced with microtome and pattern is transfered from flakes to substrate by plasma etching. Experimental Section. Group of Self-organized Nanoporous Materials in Technical University of Denmark has developed series of block copolymers of Polybutadiene-b-Polydimethylsiloxane (PB...... with hexagonal pattern were transferred onto silicon wafer for plasma etching. Results and Discussion. After flakes had been removed hexagonal arrays of holes were observed on the silicon. Quality of observed structures depends on etching time. The longer etching time is the large optimal thickness of flake...... PDMS can be chemically etched from the PB matrix by tetrabutylammonium fluoride in tetrahydrofuran and macroscopic nanoporous PB piece is obtained. Both block-copolymer piece and nanoporous polymer piece were sliced with cryomicrotome perpendicular to the axis of cylinder alignment and flakes...

  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. Alternating voltage induced ordered anatase TiO2 nanopores: An electrochemical investigation of sodium storage

    Science.gov (United States)

    Li, Simin; Xie, Lingling; Hou, Hongshuai; Liao, Hanxiao; Huang, Zhaodong; Qiu, Xiaoqing; Ji, Xiaobo

    2016-12-01

    Anatase TiO2 nanopores are successfully prepared through alternating voltage induced electrochemical synthesis (AVIES) approach at room temperature. When utilizing TiO2 nanoporous materials as an anode for Na-ion battery, it delivers a reversible charge-discharge capacity of around 180 mA h g-1 at 0.2 C (67 mA g-1) after 200 cycles. Meanwhile, it also shows a good cycling performance and a high rate capability due to unique nanoporous structures, which promote electrolyte wetting and facilitate diffusion of Na+. Additionally, cyclic voltammetry demonstrate that the sodium-ion storage of as-prepared TiO2 is a cooperative control behavior of diffusion and capacitance, but mainly controlled by capacitive behavior, which further facilitates a rapid (de-)intercalation of Na+.

  20. Super-Diffusive Gas Recovery from Nanopores

    CERN Document Server

    Wu, Haiyi; Qiao, Rui

    2016-01-01

    Understanding the recovery of gas from reservoirs featuring pervasive nanopores is essential for effective shale gas extraction. Classical theories cannot accurately predict such gas recovery and many experimental observations are not well understood. Here we report molecular simulations of the recovery of gas from single nanopores, explicitly taking into account molecular gas-wall interactions. We show that, in very narrow pores, the strong gas-wall interactions are essential in determining the gas recovery behavior both quantitatively and qualitatively. These interactions cause the total diffusion coefficients of the gas molecules in nanopores to be smaller than those predicted by kinetic theories, hence slowing down the rate of gas recovery. These interactions also lead to significant adsorption of gas molecules on the pore walls. Because of the desorption of these gas molecules during gas recovery, the gas recovery from the nanopore does not exhibit the usual diffusive scaling law (i.e., the accumulative ...

  1. Improved Algorithms for Nanopore Signal Processing

    CERN Document Server

    Arjmandi, Nima; Lagae, Liesbet; Borghs, Gustaaf

    2012-01-01

    Nanopore resistive pulse techniques are based on analysis of current or voltage spikes in the recorded signal. These spikes result from translocation of nanometer sized analytes through a nanopore. The most important information that needs to be extracted is the duration, amplitude and number of the translocation spikes. The recorded signal is usually considerably noisy, with a huge baseline drift and hundreds of translocation spikes. Thus, incorporation of suitable signal processing algorithms is necessary for correct and fast detection of all the translocation spikes and to accurately measure their amplitude and duration. Generally, low-pass filtering is used for denoising, averaging is used for baseline detection, and thresholding is used for spike detection and measurement. Here we present novel algorithms and specifically developed software for nanopore signal processing that are significantly improving the accuracy of the nanopore measurements. It includes an improved method for baseline removing, an op...

  2. DNA sequencing by nanopores: advances and challenges

    Science.gov (United States)

    Agah, Shaghayegh; Zheng, Ming; Pasquali, Matteo; Kolomeisky, Anatoly B.

    2016-10-01

    Developing inexpensive and simple DNA sequencing methods capable of detecting entire genomes in short periods of time could revolutionize the world of medicine and technology. It will also lead to major advances in our understanding of fundamental biological processes. It has been shown that nanopores have the ability of single-molecule sensing of various biological molecules rapidly and at a low cost. This has stimulated significant experimental efforts in developing DNA sequencing techniques by utilizing biological and artificial nanopores. In this review, we discuss recent progress in the nanopore sequencing field with a focus on the nature of nanopores and on sensing mechanisms during the translocation. Current challenges and alternative methods are also discussed.

  3. DNA nanopore translocation in glutamate solutions

    Science.gov (United States)

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

    2015-08-01

    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 solutions. We show that it has a linear response at typical voltages and can be used to detect DNA translocations through a nanopore. The glutamate anion also acts as a redox-capable thickening agent, with high-viscosity solutions capable of slowing down the DNA translocation process by up to 11 times, with a corresponding 7 time reduction in signal. These results demonstrate that glutamate can replace chloride as the primary anion in nanopore resistive pulse sensing.

  4. Modeling of Self-Healing Polymer Composites Reinforced with Nanoporous Glass Fibers

    OpenAIRE

    Privman, Vladimir; Dementsov, Alexander; Sokolov, Igor

    2006-01-01

    We report on our progress towards continuum rate equation modeling, as well as numerical simulations, of self-healing of fatigue in composites reinforced with glue carrying nanoporous fibers. We conclude that with the proper choice of the material parameters, effects of fatigue can be partially overcome and degradation of mechanical properties can be delayed.

  5. Enhanced Strain in Functional Nanoporous Gold with a Dual Microscopic Length Scale Structure

    NARCIS (Netherlands)

    Detsi, Eric; Punzhin, Sergey; Rao, Jiancun; Onck, Patrick R.; De Hosson, Jeff Th. M.

    2012-01-01

    We have synthesized nanoporous Au with a dual microscopic length scale by exploiting the crystal structure of the alloy precursor. The synthesized mesoscopic material is characterized by stacked Au layers of submicrometer thickness. In addition, each layer displays nanoporosity through the entire bu

  6. 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.

  7. 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.

  8. Electrochemical Properties of Nanocomposite Nanoporous Carbon / Nickel Hydroxide

    Directory of Open Access Journals (Sweden)

    O.M. Hemiy

    2016-12-01

    Full Text Available The electrochemical properties of composite nanoporous carbon / nickel hydroxide as electrode material for hybrid supercapacitors were investigated. Fast reversible faradaic reactions flow was determined in connection with chemical makeup of the -Ni(OH2/С composite. It is shown that increase of nickel hydroxide concentration can intensify reactions. It is found that clean -Ni(OH2 has 238 F/g of specific capacity, but -Ni(OH2/С nanocomposite with 90 % nickel hydroxide has 292 F/g. Such capacity value can be considered as a maximum for these composites.

  9. Ion selectivity of graphene nanopores

    Science.gov (United States)

    Rollings, Ryan C.; Kuan, Aaron T.; Golovchenko, Jene A.

    2016-04-01

    As population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores preferentially permit the passage of K+ cations over Cl- anions with selectivity ratios of over 100 and conduct monovalent cations up to 5 times more rapidly than divalent cations. Surprisingly, the observed K+/Cl- selectivity persists in pores even as large as about 20 nm in diameter, suggesting that high throughput, highly selective graphene electrodialysis membranes can be fabricated without the need for subnanometer control over pore size.

  10. The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Krishna Kant

    2014-11-01

    Full Text Available 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.

  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. 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.

  13. 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.

  14. Nanoporous oxidic solids: the confluence of heterogeneous and homogeneous catalysis.

    Science.gov (United States)

    Thomas, John Meurig; Hernandez-Garrido, Juan Carlos; Raja, Robert; Bell, Robert G

    2009-04-28

    The several factors that render certain kinds of nanoporous oxidic solids valuable for the design of a wide range of new heterogeneous catalysts are outlined and exemplified. These factors include: (i), their relative ease of preparation, when both mesoporous siliceous frameworks (ca. 20 to 250 A diameter pores) and microporous framework-substituted aluminophosphates (ca. 4 to 14 A diameter pores) can be tailored to suit particular catalytic needs according to whether regiospecific or enantio- or shape-selective conversions are the goal; (ii), the enormous internal (three-dimensional) areas that these nanoporous solids possess (typically 10(3) m(2) g(-1)) and the consequential ease of access of reactants through the internal pores of the solids; (iii), the ability, by judicious solid-state preparative methods to assemble spatially isolated, single-site active centres at the internal surfaces of these open-structure solids, thereby making the heterogeneous catalyst simulate the characteristic features of homogenous and enzymatic catalysts; (iv), the wide variety of in situ, time-resolved and ex situ experimental techniques, coupled with computational methods, that can pin-point the precise structure of the active site under operating conditions and facilitate the formulation of reaction intermediates and mechanisms. Varieties of catalysts are described for the synthesis (often under environmentally benign and solvent-free conditions) of a wide range of organic materials including commodity chemicals (such as adipic and terephthalic acid), fine and pharmaceutical chemicals (e.g. vitamin B(3)), alkenes, epoxides, and for the photocatalytic preferential destruction of carbon monoxide in the presence of hydrogen. Nanoporous oxidic solids are ideal materials to investigate the phenomenology of catalysis because, in many of them, little distinction exists between a model and a real catalyst.

  15. Mobility and carrier density in nanoporous indium tin oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Weissbon, Jaqueline; Gondorf, Andreas; Geller, Martin; Lorke, Axel [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany); Inhester, Martina; Prodi-Schwab, Anna; Adam, Dieter [Evonik Degussa GmbH, D-45772 Marl (Germany)

    2011-07-01

    Indium tin oxide (ITO) has become an indispensable material for a range of electronic devices. It is transparent in the entire visible range and electrically conducting, hence, a well suited material for transparent electrodes. An interesting possibility to realize transparent, conducting films without the use of vacuum techniques is the printing of dispersions containing ITO nanoparticles. We study here the charge carrier concentration and mobility of various nanoporous indium tin oxide (ITO) films, using Hall measurements and optical spectroscopy. For the carrier density inside the particles (2-4 . 10{sup 20} cm{sup -3}), the results of these complementary measurement techniques are in good agreement with each other and suggest that even in highly porous materials the common equations for the Hall resistance can be applied. However, for the mobilities in these layers the results differ very strongly: from 50 (cm{sup 2})/(Vs) in optical spectroscopy (which is comparable to bulk ITO) to 0.4 (cm{sup 2})/(Vs) in Hall measurements.This suggests that the mobility for electrical transport in nanoporous ITO films is strongly suppressed by scattering at interparticle boundaries.

  16. A nano-frost array technique to prepare nanoporous PVDF membranes

    Science.gov (United States)

    Lee, Min Kyung; Lee, Jonghwi

    2014-07-01

    Frost, the solid deposition of water vapor from humid air, forms on the surface of a solid substrate when its temperature drops below the freezing point of water. In this study, we demonstrate how this natural phenomenon can be applied to develop novel nanoporous materials. The solvent annealing of polyvinylidene fluoride (PVDF) infiltrated into nanopores induced template-directed dewetting thus preparing nanoembossing films. Then, water nanodroplets formed on the cold polymer nanopatterned surfaces following the embossing patterns, similar to dew formation on the ground. Subsequently, the nanodroplets were frozen and then removed by freeze-drying. This nano-frost array technique produced nanoporous PVDF membranes with an average thickness of 250 (+/-48) nm. It was revealed that the nanopatterned surface formed by solvent annealing played an important role in achieving a nano-frost array with an adjustable size. Additionally, the freezing process led to significant changes of the PVDF crystallinity and polymorphism. Our results prove that the nano-frost array technique can be broadly used to design ordered nanoporous structures and provide new prospects in nanomaterial fields.Frost, the solid deposition of water vapor from humid air, forms on the surface of a solid substrate when its temperature drops below the freezing point of water. In this study, we demonstrate how this natural phenomenon can be applied to develop novel nanoporous materials. The solvent annealing of polyvinylidene fluoride (PVDF) infiltrated into nanopores induced template-directed dewetting thus preparing nanoembossing films. Then, water nanodroplets formed on the cold polymer nanopatterned surfaces following the embossing patterns, similar to dew formation on the ground. Subsequently, the nanodroplets were frozen and then removed by freeze-drying. This nano-frost array technique produced nanoporous PVDF membranes with an average thickness of 250 (+/-48) nm. It was revealed that the

  17. Poretools: a toolkit for analyzing nanopore sequence data

    OpenAIRE

    Loman, Nicholas J.; Quinlan, Aaron R.

    2014-01-01

    Motivation: Nanopore sequencing may be the next disruptive technology in genomics, owing to its ability to detect single DNA molecules without prior amplification, lack of reliance on expensive optical components, and the ability to sequence long fragments. The MinION™ from Oxford Nanopore Technologies (ONT) is the first nanopore sequencer to be commercialized and is now available to early-access users. The MinION™ is a USB-connected, portable nanopore sequencer that permits real-time analysi...

  18. Filter casting nanoscale porous materials

    Science.gov (United States)

    Hayes, Joel Ryan; Nyce, Gregory Walker; Kuntz, Jushua David

    2013-12-10

    A method of producing nanoporous material includes the steps of providing a liquid, providing nanoparticles, producing a slurry of the liquid and the nanoparticles, removing the liquid from the slurry, and producing monolith.

  19. Removal of thorium (IV) ions from aqueous solution by a novel nanoporous ZnO: Isotherms, kinetic and thermodynamic studies.

    Science.gov (United States)

    Kaynar, Ümit H; Ayvacıklı, Mehmet; Hiçsönmez, Ümran; Kaynar, Sermin Çam

    2015-12-01

    The adsorption of thorium (IV) from aqueous solutions onto a novel nanoporous ZnO particles prepared by microwave assisted combustion was studied using batch methods under different experimental conditions. The effect of contact time, solution pH, initial concentration and temperature on adsorption process was studied. The ability of this material to remove Th (IV) from aqueous solution was characterises by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption percent and distribution coefficient for nanoporous ZnO powders in optimum conditions were 97% ± 1.02; 8080 L kg(-1)for Th (IV), respectively. Based on the Langmuir model, the maximum adsorption capacity of nanoporous ZnO for Th (IV) was found to be 1500 g kg(-1). Thermodynamic parameters were determined and discussed. The results indicated that nanoporous ZnO was suitable as sorbent material for recovery and adsorption of Th (IV) ions from aqueous solutions. The radioactive Th (VI) in surface water, sea water and waste waters from technologies producing nuclear fuels, mining (uranium and thorium) and laboratories working with radioactive materials (uranium and thorium) can be removed with this nanoporous ZnO. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Self-assembled nanowire arrays as three-dimensional nanopores for filtration of DNA molecules.

    Science.gov (United States)

    Rahong, Sakon; Yasui, Takao; Yanagida, Takeshi; Nagashima, Kazuki; Kanai, Masaki; Meng, Gang; He, Yong; Zhuge, Fuwei; Kaji, Noritada; Kawai, Tomoji; Baba, Yoshinobu

    2015-01-01

    Molecular filtration and purification play important roles for biomolecule analysis. However, it is still necessary to improve efficiency and reduce the filtration time. Here, we show self-assembled nanowire arrays as three-dimensional (3D) nanopores embedded in a microfluidic channel for ultrafast DNA filtration. The 3D nanopore structure was formed by a vapor-liquid-solid (VLS) nanowire growth technique, which allowed us to control pore size of the filtration material by varying the number of growth cycles. λ DNA molecules (48.5 kbp) were filtrated from a mixture of T4 DNA (166 kbp) at the entrance of the 3D nanopore structure within 1 s under an applied electric field. Moreover, we observed single DNA molecule migration of T4 and λ DNA molecules to clarify the filtration mechanism. The 3D nanopore structure has simplicity of fabrication, flexibility of pore size control and reusability for biomolecule filtration. Consequently it is an excellent material for biomolecular filtration.

  1. Preparation of nanoporous titania spherical nanoparticles

    Science.gov (United States)

    Shiba, Kota; Sato, Soh; Matsushita, Takayuki; Ogawa, Makoto

    2013-03-01

    Preparation of nanoporous titania particles from well-defined titania-octadecylamine (titania-ODA) hybrid spherical particles with 450 nm in size, which were prepared by the method reported previously (Chem. Commun., 2009, pp. 6851-6853 [39]; RSC Adv., 2012, vol. 2, pp. 1343-1349 [40]), was studied. ODA was removed by solvent extraction with acidic ethanol to obtain nanoporous titania particles and subsequent calcination led to the formation of nanoporous titania particles with the nanopore size ranging from 2 to 4 nm depending on the calcination temperature. The as-synthesized titania was amorphous and was transformed into anatase (at around 300 °C) and rutile (at around 600 °C) by the heat treatment. The phase transition behavior was discussed in comparison with that of as-synthesized titania-ODA particles without ODA removal. Spherical particles of titania-ODA hybrids with 70 nm in size were also transformed into nanoporous titania particles composed of anatase crystallites by the washing and calcination at 500 °C for 1 h.

  2. 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.

  3. 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)

  4. 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.

  5. 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.

  6. 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...

  7. Tailored nanoporous gold for ultrahigh fluorescence enhancement.

    Science.gov (United States)

    Lang, X Y; Guan, P F; Fujita, T; Chen, M W

    2011-03-07

    We report molecular fluorescence enhancement of free-standing nanoporous gold in which the nanoporosity can be arbitrarily tailored by the combination of dealloying and electroless gold plating. The nanoporous gold fabricated by this facile method possesses unique porous structures with large gold ligaments and very small pores, and exhibits significant improvements in surface enhanced fluorescence as well as structure rigidity. It demonstrates that the confluence effect of improved quantum yield and excitation of fluorophores is responsible for the large fluorescence enhancement due to the near-field enhancement of nanoporous gold, which arises from the strong electromagnetic coupling between neighboring ligaments and the weakening of plasmon damping of the large ligaments because of the small pore size and large ligament size, respectively.

  8. Vibrational spectra of molecular fluids in nanopores

    Science.gov (United States)

    Arakcheev, V. G.; Morozov, V. B.

    2012-12-01

    Coherent anti-Stokes Raman spectroscopy (CARS) is applied for quantitative analysis of carbon dioxide phase composition in pores of nanoporous glass samples at nearcritical temperatures. Measurements of the 1388 1/cm Q-branch were made in a wide pressure range corresponding to coexistence of gas (gas-like), adsorbed and condensed phases within pores. At temperatures several degrees below the critical value, CARS spectra behavior is easy to interpret in terms of thermodynamic model of surface adsorption and capillary condensation. It allows estimating mass fractions of different phase components. Moreover, spectra measured at near critical temperatures 30.5 and 33°C have pronounced inhomogeneous shapes and indicate the presence of condensed phase in the volume of pores. The effect obviously reflects the fluid behaviour near the critical point in nanopores. Pores with smaller radii are filled with condensed phase at lower pressures. The analysis of the CARS spectra is informative for quantitative evaluation of phase composition in nanopores.

  9. Polyelectrolyte Threading through a Nanopore

    Directory of Open Access Journals (Sweden)

    Pai-Yi Hsiao

    2016-03-01

    Full Text Available Threading charged polymers through a nanopore, driven by electric fields E, is investigated by means of Langevin dynamics simulations. The mean translocation time 〈 τ 〉 is shown to follow a scaling law Nα, and the exponent α increases monotonically from 1.16 (4 to 1.40 (3 with E. The result is double-checked by the calculation of mean square displacement of translocation coordinate, which asserts a scaling behavior tβ (for t near τ with β complying with the relation αβ = 2. At a fixed chain length N, 〈τ〉 displayed a reciprocal scaling behavior E−1 in the weak and also in the strong fields, connected by a transition E−1.64(5 in the intermediate fields. The variations of the radius of gyration of chain and the positions of chain end are monitored during a translocation process; far-from-equilibrium behaviors are observed when the driving field is strong. A strong field can strip off the condensed ions on the chain when it passes the pore. The total charges of condensed ions are hence decreased. The studies for the probability and density distributions reveal that the monomers in the trans-region are gathered near the wall and form a pancake-like density profile with a hump cloud over it in the strong fields, due to fast translocation.

  10. DNA translocations through solid-state plasmonic nanopores.

    Science.gov (United States)

    Nicoli, Francesca; Verschueren, Daniel; Klein, Misha; Dekker, Cees; Jonsson, Magnus P

    2014-12-10

    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.

  11. 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.

  12. Sub-5 nm graphene nanopore fabrication by nitrogen ion etching induced by a low-energy electron beam.

    Science.gov (United States)

    Fox, Daniel S; Maguire, Pierce; Zhou, Yangbo; Rodenburg, Cornelia; O'Neill, Arlene; Coleman, Jonathan N; Zhang, Hongzhou

    2016-05-13

    A flexible and efficient method to fabricate nanopores in graphene has been developed. A focused, low-energy (5 keV) electron beam was used to locally activate etching of a graphene surface in a low pressure (0.3 Pa) N2 environment. Nanopores with sub-5 nm diameters were fabricated. The lattice structure of the graphene was observed to recover within 20 nm of the nanopore edge. Nanopore growth rates were investigated systematically. The effects of nitrogen pressure, electron beam dwell time and beam current were characterised in order to understand the etching mechanism and enable optimisation of the etching parameters. A model was developed which describes how the diffusion of ionised nitrogen affects the nanopore growth rate. Etching of other two-dimensional materials was attempted as demonstrated with MoS2. The lack of etching observed supports our model of a chemical reaction-based mechanism. The understanding of the etching mechanism will allow more materials to be etched by selection of an appropriate ion species.

  13. Observation of ionic Coulomb blockade in nanopores

    Science.gov (United States)

    Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; di Ventra, Massimiliano; Radenovic, Aleksandra

    2016-08-01

    Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels.

  14. 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......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...

  15. Nanoporous thin film platform for biophotonic sensors

    Science.gov (United States)

    Alla, Suresh; Solanki, Rina; Mattley, Yvette D.; Dabhi, Harish; Shahriari, Mahmoud R.

    2009-02-01

    A Nanoporous glass matrix is developed to encapsulate molecular probes for monitoring important biological parameters such as DO. The hydrophobic nanoporous host matrix is designed and fabricated using room temperature sol gel technique. The doped sol gel is then coated on biocompatible self adhesive patches or directly coated on the biocontainers. We demonstrate the application of this technique in non-invasive monitoring DO as well as oxygen partial pressure in a closed fermentation process as well as in a cell culture plate during bacterial growth. Dynamic response of sensor, sensitivity and accuracy is also demonstrated in this paper.

  16. Characterization of Interstrand DNA-DNA Cross-Links Using the α-Hemolysin Protein Nanopore.

    Science.gov (United States)

    Zhang, Xinyue; Price, Nathan E; Fang, Xi; Yang, Zhiyu; Gu, Li-Qun; Gates, Kent S

    2015-12-22

    Nanopore-based sensors have been studied extensively as potential tools for DNA sequencing, characterization of epigenetic modifications such as 5-methylcytosine, and detection of microRNA biomarkers. In the studies described here, the α-hemolysin protein nanopore embedded in a lipid bilayer was used for the detection and characterization of interstrand cross-links in duplex DNA. Interstrand cross-links are important lesions in medicinal chemistry and toxicology because they prevent the strand separation that is required for read-out of genetic information from DNA in cells. In addition, interstrand cross-links are used for the stabilization of duplex DNA in structural biology and materials science. Cross-linked DNA fragments produced unmistakable current signatures in the nanopore experiment. Some cross-linked substrates gave irreversible current blocks of >10 min, while others produced long current blocks (10-100 s) before the double-stranded DNA cross-link translocated through the α-hemolysin channel in a voltage-driven manner. The duration of the current block for the different cross-linked substrates examined here may be dictated by the stability of the duplex region left in the vestibule of the nanopore following partial unzipping of the cross-linked DNA. Construction of calibration curves measuring the frequency of cross-link blocking events (1/τon) as a function of cross-link concentration enabled quantitative determination of the amounts of cross-linked DNA present in samples. The unique current signatures generated by cross-linked DNA in the α-HL nanopore may enable the detection and characterization of DNA cross-links that are important in toxicology, medicine, and materials science.

  17. Water Purification across MoS2 Nano-porous Membranes

    Science.gov (United States)

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

    2015-11-01

    A 2D material, molybdenum disulfide (MoS2) , is proposed as a nano-porous membrane for water desalination. By performing detailed molecular dynamics simulations, we find that salt ions are rejected efficiently across a single-layer MoS2 while water permeates at high rates. Depending on the pore area, which ranges from 20 to 60 Å2, the nanopore allows less than 12% of ions to pass through even at theoretically high pressures of 350 MPa. Water permeation across the MoS2 membrane is found to be as high as 12 L/cm2/day/MPa which is at least two orders of magnitude higher than that of other existing nano-porous membranes. Pore chemistry is shown to be one of the important factors leading to large water fluxes. MoS2 pore edges terminated with only molybdenum atoms result in higher fluxes which are about 70% higher than that of graphene nanopores. These findings are explained and supported by the permeation coefficients, energy barriers, water density and velocity distributions in the pores.

  18. Nanoporous Monolithic Microsphere Arrays Have Anti-Adhesive Properties Independent of Humidity

    Directory of Open Access Journals (Sweden)

    Anna Eichler-Volf

    2016-05-01

    Full Text Available Bioinspired artificial surfaces with tailored adhesive properties have attracted significant interest. While fibrillar adhesive pads mimicking gecko feet are optimized for strong reversible adhesion, monolithic microsphere arrays mimicking the slippery zone of the pitchers of carnivorous plants of the genus Nepenthes show anti-adhesive properties even against tacky counterpart surfaces. In contrast to the influence of topography, the influence of relative humidity (RH on adhesion has been widely neglected. Some previous works deal with the influence of RH on the adhesive performance of fibrillar adhesive pads. Commonly, humidity-induced softening of the fibrils enhances adhesion. However, little is known on the influence of RH on solid anti-adhesive surfaces. We prepared polymeric nanoporous monolithic microsphere arrays (NMMAs with microsphere diameters of a few 10 µm to test their anti-adhesive properties at RHs of 2% and 90%. Despite the presence of continuous nanopore systems through which the inner nanopore walls were accessible to humid air, the topography-induced anti-adhesive properties of NMMAs on tacky counterpart surfaces were retained even at RH = 90%. This RH-independent robustness of the anti-adhesive properties of NMMAs significantly contrasts the adhesion enhancement by humidity-induced softening on nanoporous fibrillar adhesive pads made of the same material.

  19. Experimental investigation of anodized/spray pyrolysed nanoporous structure on heat transfer augmentation

    Institute of Scientific and Technical Information of China (English)

    Kalaiselvam, S.; Gugan, M.S.; Kuraloviyan, E.; Meganathan, R.; Niruthiya Priyan, A.; Swaminathan, M.R.

    2009-01-01

    This paper analyzes the effects of nanoporous surface on heat transfer temperaments of assorted thermal con-ducting materials. A phenomenal proposal of wielding the surface roughness to ameliorate the heat transfer rate has been discovered. The maximum increase of heat transfer rate procured by nanoporous layers is 133.3% higher than the polished bare metals of surface roughness 0.2 μm. This plays an imperative role in designing compact re-frigeration systems, chemical and thermal power plants. Experimental results picture a formidable upswing of 58.3% heat transfer in chemically etched metals of surface roughness 3 μm, 133.3% in nanoporous surface of po-rosity 75-95 nm formed by electrochemical anodization, and porosity of 40-50 nm formed by spray pyrolysis in-creases the heat transfer by 130%. Effects of porosity, flow velocity and scaling on the energy transfer are also scrutinized. This paper also analyzes the multifarious modes of nanoporous fabrication, to connive both prodi-gious and provident system.

  20. Atomically dispersed Pd catalysts in graphyne nanopore: formation and reactivity

    Science.gov (United States)

    Gu, Yongbing; Chen, Xianlang; Cao, Yongyong; Zhuang, Guilin; Zhong, Xing; Wang, Jianguo

    2017-07-01

    The formation of single-atom noble metal catalysts on carbon materials remains a challenge due to the weak interaction between metals and pristine carbon. By means of density functional theory (DFT) calculations, it is found that the atomically dispersed Pd in graphyne nanopore is much more stable than that of relative Pd clusters. The large diffusion barrier of Pd from the most stable hollow site to the bridge site confirms the kinetic stability of such structures. While CO adsorption causes the pulling of Pd from graphyne nanopore due to the low diffusion barrier, based on DFT calculations, which can be further confirmed by ab initio molecular dynamic simulations. Finally, CO oxidation on the reconstruction of Pd@graphyne exhibits an energy barrier of 0.62 eV in the rate-limiting step through the Langmuir-Hinshelwood mechanism. After the reaction, the catalyst can be restored to the original atomically dispersed state again. This study shows graphyne is an excellent support for an atomically dispersed or single-metal catalyst.

  1. 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.

  2. Reticulated Nanoporous Polymers by Controlled Polymerization-Induced Microphase Separation

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Myungeun; Hillmyer, Marc A. (UMM)

    2013-04-08

    Materials with percolating mesopores are attractive for applications such as catalysis, nanotemplating, and separations. Polymeric frameworks are particularly appealing because the chemical composition and the surface chemistry are readily tunable. We report on the preparation of robust nanoporous polymers with percolating pores in the 4- to 8-nanometer range from a microphase-separated bicontinuous precursor. We combined polymerization-induced phase separation with in situ block polymer formation from a mixture of multifunctional monomers and a chemically etchable polymer containing a terminal chain transfer agent. This marriage results in microphase separation of the mixture into continuous domains of the etchable polymer and the emergent cross-linked polymer. Precise control over pore size distribution and mechanical integrity renders these materials particularly suited for various advanced applications.

  3. Carbon dioxide sorption in a nanoporous octahedral molecular sieve

    Science.gov (United States)

    Williamson, Izaak; Nelson, Eric B.; Li, Lan

    2015-08-01

    We have performed first-principles density functional theory calculations, incorporated with van der Waals interactions, to study CO2 adsorption and diffusion in nanoporous solid—OMS-2 (Octahedral Molecular Sieve). We found the charge, type, and mobility of a cation, accommodated in a porous OMS-2 material for structural stability, can affect not only the OMS-2 structural features but also CO2 sorption performance. This paper targets K+, Na+, and Ba2+ cations. First-principles energetics and electronic structure calculations indicate that Ba2+ has the strongest interaction with the OMS-2 porous surface due to valence electrons donation to the OMS-2 and molecular orbital hybridization. However, the Ba-doped OMS-2 has the worst CO2 uptake capacity. We also found evidence of sorption hysteresis in the K- and Na-doped OMS-2 materials.

  4. 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

  5. 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...

  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 relat

  7. Preparation of three-dimensional nanoporous Si using dealloying by metallic melt and application as a lithium-ion rechargeable battery negative electrode

    Science.gov (United States)

    Wada, Takeshi; Yamada, Junpei; Kato, Hidemi

    2016-02-01

    Silicon is a promising material for negative electrode in Li-ion batteries because of high gravimetric capacity. A Si nanomaterial that can accommodate volume expansion accompanied by lithiation is needed for practical application in Li-ion batteries. We prepare three-dimensional nanoporous interconnected silicon material with controlled pore and ligament sizes by dealloying using an Mg-Si precursor and Bi melt. The Mg atoms in the precursor selectively dissolve into Bi, and the remaining Si atoms self-organize into a nanoporous structure with characteristic length ranging from several ten to hundred nanometer. The Li-ion battery electrodes made from nanoporous silicon exhibit higher capacities, increased cycle lives, and improved rate performances compared with those made from commercial Si nanoparticles. Measurements on the electrical resistivity and electrode thickness change by lithiation/delithiation suggest that the superior performance of nanoporous Si electrode originates from the following: (1) The nanoporous Si has much lower electrical resistivity compared with that of the nanoparticle Si owing to the n-type dopant incorporated during dealloying. (2) The nanoporous Si-based electrode has higher porosity owing to the presence of intra-particle pores, which can accommodate Si expansion up to higher levels of lithiation.

  8. From condiment to metal-organic framework and its derived 3D architecture nanoporous carbon for supercapacitor electrodes

    Science.gov (United States)

    Wang, Qiang; Lu, Xiaowang; Chen, Zhidong

    2017-02-01

    The crystalline metal-organic-framework (MOF) microrods from monosodium glutamate and zinc acetate dihydrate were spontaneously formed by mixing their solution at room temperature. After carbonization in an inert atmosphere, these MOF microrods are evolved into N and O co-doped nanoporous carbon with 3D-architecture. The model of gas bubbles is elucidated for the formation of these interconnected porous structure. As the electrode material for supercapacitor, the derived nanoporous carbon at the temperature of 800 °C exhibits good capacitance performance in alkali aqueous electrolyte.

  9. Responsive nanoporous metals: recoverable modulations on strength and shape by watering

    Science.gov (United States)

    Ye, Xing-Long; Liu, Ling-Zhi; Jin, Hai-Jun

    2016-08-01

    Many biological materials can readily modulate their mechanical properties and shape by interacting with water in the surrounding environment, which is essential to their high performance in application. In contrast, typical inorganic materials (such as the metals) cannot change their strength and shape without involving thermal/mechanical treatments. By introducing nano-scale porous structure and exploiting a simple physical concept—the water-capillarity in nanopores, here we report that a ‘dead’ metal can be transformed into a ‘smart’ material with water-responsive properties. We demonstrate that the apparent strength, volume and shape of nanoporous Au and Au(Pt) can be modulated in situ, dramatically and recoverably, in response to water-dipping and partial-drying. The amplitude of strength-modulation reaches 20 MPa, which is nearly 50% of the yield strength at initial state. This approach also leads to reversible length change up to 1.3% in nanoporous Au and a large reversible bending motion of a bi-layer strip with tip displacement of ∼20 mm, which may be used for actuation. This method is simple and effective, occurring in situ under ambient conditions and requiring no external power, analogous to biological materials. The findings may open up novel applications in many areas such as micro-robotics and bio-medical devices.

  10. Fabrication and Characterization of Nanoporous Niobia, and Nanotubular Tantala, Titania and Zirconia via Anodization

    Science.gov (United States)

    Minagar, Sepideh; Berndt, Christopher C.; Wen, Cuie

    2015-01-01

    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. PMID:25837724

  11. Low frequency sonochemical synthesis of nanoporous amorphous manganese dioxide (MnO{sub 2}) and adsorption of remazol reactive dye

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Siti Zubaidah; Yusop, Muhammad Rahimi; Othman, Mohamed Rozali, E-mail: rozali@ukm.edu.my [School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)

    2015-09-25

    Nanoporous amorphous-MnO{sub 2} was synthesized by sonochemical process (sonication) on the solid manganese (II) acetate tetrahydrate (Mn(CH{sub 3}COO){sub 2}.4H{sub 2}O) in 0.1 M KMnO{sub 4}. The product was characterized by X-ray diffraction (XRD), morphology of the material was scanned by Field Emission Scanning Electron Microscopy (FE-SEM) and absorptions of MnO{sub 2} bonding was characterized by Fourier Transform Infra-Red Spectrometer (FT-IR). Remazol reactive dye or Red 3BS, was used in the adsorption study using nanoporous amorphous-MnO{sub 2}. In batch experiment, 10 ppm of Remazol reactive dye was used and experiment was carried out at room temperature. Adsorption of Remazol dye on 0.2g synthesized nanoporous amorphous-MnO{sub 2} showed 99 – 100% decolorization.

  12. Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids

    Science.gov (United States)

    Lauerer, Alexander; Binder, Tomas; Chmelik, Christian; Miersemann, Erich; Haase, Jürgen; Ruthven, Douglas M.; Kärger, Jörg

    2015-07-01

    Under certain conditions, during binary mixture adsorption in nanoporous hosts, the concentration of one component may temporarily exceed its equilibrium value. This implies that, in contrast to Fick's Law, molecules must diffuse in the direction of increasing rather than decreasing concentration. Although this phenomenon of `overshooting' has been observed previously, it is only recently, using microimaging techniques, that diffusive fluxes in the interior of nanoporous materials have become accessible to direct observation. Here we report the application of interference microscopy to monitor `uphill' fluxes, covering the entire period of overshooting from initiation until final equilibration. It is shown that the evolution of the profiles can be adequately predicted from the single-component diffusivities together with the binary adsorption equilibrium data. The guest molecules studied (carbon dioxide, ethane and propene) and the host material (ZSM-58 or DDR) are of practical interest in relation to the development of kinetically selective adsorption separation processes.

  13. Nanoporous SiO{sub 2}/TiO{sub 2} coating with enhanced interfacial compatibility for orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaobing, E-mail: zhaoxiaobing00@163.com [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Cao, Hengchun; You, Jing; Cheng, Xingbao [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Xie, Youtao [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Cao, Huiliang [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • The SiO{sub 2}/TiO{sub 2} coatings were fabricated on the cp-Ti substrates by plasma spraying. • Nanoporous topography was formed on SiO{sub 2}/TiO{sub 2} coating by HF-hydrothermal etching. • The hydrothermal conditions had important effects on the nanoporous topographies. • Nanoporous SiO{sub 2}/TiO{sub 2} coating exhibited enhanced cytocompatibility. - Abstract: Topographic modification in nanoscale is one of the most often used strategies to enhance the interfacial biocompatibility of implant materials. The aim of this work is to produce SiO{sub 2}/TiO{sub 2} coatings with nanoporous structures and favorable biological properties by atmospheric plasma spraying technology and subsequently hydrothermal etching method in hydrogen fluoride solution. The effects of hydrothermal time and temperature on the microstructures and osteoblast behavior of the SiO{sub 2}/TiO{sub 2} coatings were investigated. Results demonstrated that the as-sprayed SiO{sub 2}/TiO{sub 2} coating was mainly composed of rutile and quartz phases. After etching, nanoporous topographies were formed on the surface of the coatings and the hydrothermal parameters had important influences on the size and shape of the pores. The interconnected network pores on the coating surface could only produce at the appropriate hydrothermal conditions (the hydrothermal time and temperature were 60 min and 100 °C, respectively). Compared to TiO{sub 2} and SiO{sub 2}/TiO{sub 2} coatings, nanoporous SiO{sub 2}/TiO{sub 2} coatings could enhance osteoblast adhesion and promote cell proliferation. The results suggested the potential application of the porous coatings for enhancing the biological performance of the currently used dental and orthopedic implant materials.

  14. 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.

  15. Electrical pulse fabrication of graphene nanopores in electrolyte solution

    Energy Technology Data Exchange (ETDEWEB)

    Kuan, Aaron T.; Szalay, Tamas [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Lu, Bo [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Xie, Ping [Oxford Nanopore Technologies, One Kendall Square, Cambridge, Massachusetts 02139 (United States); Golovchenko, Jene A., E-mail: golovchenko@physics.harvard.edu [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2015-05-18

    Nanopores in graphene membranes can potentially offer unprecedented spatial resolution for single molecule sensing, but their fabrication has thus far been difficult, poorly scalable, and prone to contamination. We demonstrate an in-situ fabrication method that nucleates and controllably enlarges nanopores in electrolyte solution by applying ultra-short, high-voltage pulses across the graphene membrane. This method can be used to rapidly produce graphene nanopores with subnanometer size accuracy in an apparatus free of nanoscale beams or tips.

  16. 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.

  17. Nanopore-based sequencing and detection of nucleic acids.

    Science.gov (United States)

    Ying, Yi-Lun; Zhang, Junji; Gao, Rui; Long, Yi-Tao

    2013-12-09

    Nanopore-based techniques, which mimic the functions of natural ion channels, have attracted increasing attention as unique methods for single-molecule detection. The technology allows the real-time, selective, high-throughput analysis of nucleic acids through both biological and solid-state nanopores. In this Minireview, the background and latest progress in nanopore-based sequencing and detection of nucleic acids are summarized, and light is shed on a novel platform for nanopore-based detection. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Nanopore-based Fourth-generation DNA Sequencing Technology

    Institute of Scientific and Technical Information of China (English)

    Yanxiao Feng; Yuechuan Zhang; Cuifeng Ying; Deqiang Wang; Chunlei Du

    2015-01-01

    Nanopore-based sequencers, as the fourth-generation DNA sequencing technology, have the potential to quickly and reliably sequence the entire human genome for less than $1000, and possibly for even less than$100. The single-molecule techniques used by this technology allow us to further study the interaction between DNA and protein, as well as between protein and protein. Nanopore analysis opens a new door to molecular biology investigation at the single-molecule scale. In this article, we have reviewed academic achievements in nanopore technology from the past as well as the latest advances, including both biological and solid-state nanopores, and discussed their recent and potential applications.

  19. Radiative human body cooling by nanoporous polyethylene textile

    Science.gov (United States)

    Hsu, Po-Chun; Song, Alex Y.; Catrysse, Peter B.; Liu, Chong; Peng, Yucan; Xie, Jin; Fan, Shanhui; Cui, Yi

    2016-09-01

    Thermal management through personal heating and cooling is a strategy by which to expand indoor temperature setpoint range for large energy saving. We show that nanoporous polyethylene (nanoPE) is transparent to mid-infrared human body radiation but opaque to visible light because of the pore size distribution (50 to 1000 nanometers). We processed the material to develop a textile that promotes effective radiative cooling while still having sufficient air permeability, water-wicking rate, and mechanical strength for wearability. We developed a device to simulate skin temperature that shows temperatures 2.7° and 2.0°C lower when covered with nanoPE cloth and with processed nanoPE cloth, respectively, than when covered with cotton. Our processed nanoPE is an effective and scalable textile for personal thermal management.

  20. Resistive Switching in Aqueous Nanopores by Shock Electrodeposition

    CERN Document Server

    Han, Ji-Hyung; Waser, Rainer; Bazant, Martin Z

    2016-01-01

    Solid-state programmable metallization cells have attracted considerable attention as memristive elements for Redox-based Resistive Random Access Memory (ReRAM) for low-power and low-voltage applications. In principle, liquid-state metallization cells could offer the same advantages for aqueous systems, such as biomedical lab-on-a-chip devices, but robust resistive switching has not yet been achieved in liquid electrolytes, where electrodeposition is notoriously unstable to the formation of fractal dendrites. Here, the recently discovered physics of shock electrodeposition are harnessed to stabilize aqueous copper growth in polycarbonate nanopores, whose surfaces are modified with charged polymers. Stable bipolar resistive switching is demonstrated for 500 cycles with <10s retention times, prior to any optimization of the geometry or materials.

  1. Predicting hydrogen and methane adsorption in carbon nanopores for energy storage

    Science.gov (United States)

    Ihm, Yungok; Morris, James; Cooper, Valentino; Morris Lab, U. tennessee Collaboration; Advanced material Group, ORNL Collaboration

    2013-03-01

    There are increasing demands for alternate fuels for transportation, which requires safe, high energy density, lightweight storage materials. Experimental measurements and theoretical predictions show relatively low hydrogen storage capacities in various porous materials, limiting hydrogen as a viable alternative for automobiles. In this work, we use a continuum model based on van der Waals density functional (vdW-DF) calculations to elucidate the role that long-range interactions play in the hydrogen adsorption properties of model slit nanopores in carbon. The proper treatment of long-range interactions gives an optimal pore size for hydrogen storage of 8-9 Å (larger than previously predicted). Remarkably, we find a peak hydrogen density close to that of liquid H2 at ambient temperatures, in agreement with recent experimental results on pore-size dependent adsorption in nanoporous carbon. We then show that such nanopores would be better suited to storing methane, possibly providing an alternative to fill the gap between the capacity required by DOE goals and that attainable with current hydrogen storage technology. Research supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division.

  2. 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.

  3. FABRICATION AND CHARACTERATION OF NANOPOROUS SILICA FILM

    Institute of Scientific and Technical Information of China (English)

    殷明志; 张良莹; 姚熹

    2003-01-01

    Colloidal silica sol is formed by a novel hydrolyzing procedure of tetraethyl-orthosilicate(TEOS) catalyzing with NH3*H2O in aqueous mediums. Glycerol, combining with the hydrolyzed intermediates of TEOS, controls growing of the silica particles; poly(vinyl-vinyl alcohol makes the colloidal silica sol with polymeric structure and spinning, thermal strain makes the gel silica film changed into a nanoporous structure with diameter ranging 50-150 nm. Morphologies of the nanoporous silica film have been characterized; the porosities (%) is 32-64; the average dielectric constant at 1MHz region is 2.0 and 2.1; the thermal conductivity is less than 0.8. Chemical mechanism of the sol-gel process is discussed.

  4. Fracture of nanoporous organosilicate thin films

    Science.gov (United States)

    Gage, David Maxwell

    Nanoporous organosilicate thin films are attractive candidates for a number of emerging technologies, ranging from biotechnology to optics and microelectronics. However, integration of these materials is challenged by their fragile nature and susceptibility to mechanical failure. Debonding and cohesive cracking of the organosilicate film are principal concerns that threaten the reliability and yield of device structures. Despite the intense interest in these materials, there is currently a need for greater understanding of the relationship between glass structure and thermomechanical integrity. The objective of this research was to investigate strategies for improving mechanical performance through variations in film chemistry, process conditions, and pore morphology. Several approaches to effecting improvements in elastic and fracture properties were examined in depth, including post-deposition curing, molecular reinforcement using hydrocarbon network groups, and manipulation of pore size and architecture. Detailed structural characterization was employed along with quantitative fracture mechanics based testing methods. It was shown that ultra-violet irradiation and electron bombardment post-deposition treatments can significantly impact glass structure in ways that cannot be achieved through thermal activation alone. Both techniques demonstrated high porogen removal efficiency and enhanced the glass matrix through increased network connectivity and local bond rearrangements. The increases in network connectivity were achieved predominantly through the replacement of terminal groups, particularly methyl and silanol groups, with Si-O network bonds. Nuclear magnetic resonance spectroscopy was shown to be a powerful and quantitative method for gaining new insight into the underlying cure reactions and mechanisms. It was demonstrated that curing leads to significant progressive enhancement of elastic modulus and adhesive fracture energies due to increased network bond

  5. Broadband Spectroscopy of Nanoporous-Gold Promoter

    Directory of Open Access Journals (Sweden)

    S. K. Nakatani

    2014-02-01

    Full Text Available The efficiency of UV photocatalysis on TiO2 particles was increased by mixing TiO2 particles with nanoporous gold (NPG with pore diameters of 10–40 nm. This means that NPG acts as a promoter in the photocatalytic reaction of TiO2. Broadband spectroscopic results from millimeter wave to ultra violet of NPG membrane are discussed to estimate plasmonic effect on the catalysis.

  6. Understanding improved osteoblast behavior on select nanoporous anodic alumina

    Directory of Open Access Journals (Sweden)

    Ni S

    2014-07-01

    Full Text Available Siyu Ni,1 Changyan Li,1 Shirong Ni,2 Ting Chen,1 Thomas J Webster3,4 1College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, People’s Republic of China; 2Department of Pathophysiology, Wenzhou Medical University, Wenzhou, People’s Republic of China; 3Department of Chemical Engineering, College of Engineering, Northeastern University, Boston, MA, USA; 4Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: The aim of this study was to prepare different sized porous anodic alumina (PAA and examine preosteoblast (MC3T3-E1 attachment and proliferation on such nanoporous surfaces. In this study, PAA with tunable pore sizes (25 nm, 50 nm, and 75 nm were fabricated by a two-step anodizing procedure in oxalic acid. The surface morphology and elemental composition of PAA were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy analysis. The nanopore arrays on all of the PAA samples were highly regular. X-ray photoelectron spectroscopy analysis suggested that the chemistry of PAA and flat aluminum surfaces were similar. However, contact angles were significantly greater on all of the PAA compared to flat aluminum substrates, which consequently altered protein adsorption profiles. The attachment and proliferation of preosteoblasts were determined for up to 7 days in culture using field emission scanning electron microscopy and a Cell Counting Kit-8. Results showed that nanoporous surfaces did not enhance initial preosteoblast attachment, whereas preosteoblast proliferation dramatically increased when the PAA pore size was either 50 nm or 75 nm compared to all other samples (P<0.05. Thus, this study showed that one can alter surface energy of aluminum by modifying surface nano-roughness alone (and not changing chemistry through an anodization process to improve osteoblast density, and, thus, should be

  7. Tuneable graphene nanopores for single biomolecule detection

    Science.gov (United States)

    Al-Dirini, Feras; Mohammed, Mahmood A.; Hossain, Md Sharafat; Hossain, Faruque M.; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2016-05-01

    Solid-state nanopores are promising candidates for next generation DNA and protein sequencing. However, once fabricated, such devices lack tuneability, which greatly restricts their biosensing capabilities. Here we propose a new class of solid-state graphene-based nanopore devices that exhibit a unique capability of self-tuneability, which is used to control their conductance, tuning it to levels comparable to the changes caused by the translocation of a single biomolecule, and hence, enabling high detection sensitivities. Our presented quantum simulation results suggest that the smallest amino acid, glycine, when present in water and in an aqueous saline solution can be detected with high sensitivity, up to a 90% change in conductance. Our results also suggest that passivating the device with nitrogen, making it an n-type device, greatly enhances its sensitivity, and makes it highly sensitive to not only the translocation of a single biomolecule, but more interestingly to intramolecular electrostatics within the biomolecule. Sensitive detection of the carboxyl group within the glycine molecule, which carries a charge equivalent to a single electron, is achieved with a conductance change that reaches as high as 99% when present in an aqueous saline solution. The presented findings suggest that tuneable graphene nanopores, with their capability of probing intramolecular electrostatics, could pave the way towards a new generation of single biomolecule detection devices.

  8. Conical nanopore membranes. Preparation and transport properties.

    Science.gov (United States)

    Li, Naichao; Yu, Shufang; Harrell, C Chad; Martin, Charles R

    2004-04-01

    We have been investigating applications of nanopore membranes in analytical chemistry-specifically in membrane-based bioseparations, in electroanalytical chemistry, and in the development of new approaches to biosensor design. Membranes that have conically shaped pores (as opposed to the more conventional cylindrical shape) may offer some advantages for these applications. We describe here a simple plasma-etch method that converts cylindrical nanopores in track-etched polymeric membranes into conically shaped pores. This method allows for control of the shape of the resulting conical nanopores. For example, the plasma-etched pores may be cylindrical through most of the membrane thickness blossoming into cones at one face of the membrane (trumpet-shaped), or they may be nearly perfect cones. The key advantage of the conical pore shape is a dramatic enhancement in the rate of transport through the membrane, relative to an analogous cylindrical pore membrane. We demonstrate this here by measuring the ionic resistances of the plasma-etched conical pore membranes.

  9. Water adsorption in ion-bearing nanopores

    Science.gov (United States)

    Lakatos, G.; Patey, G. N.

    2007-01-01

    Grand canonical Monte Carlo simulations are used to examine the adsorption of water into cylindrical nanopores containing single ions. The isotherms for water adsorbing into nanopores with radii of 0.44, 0.54, 0.64, and 0.74nm and containing Na+, K+, Ca2+, Cl-, or F- at 298K are computed. In all cases the nanopores are found to fill at reservoir chemical potentials below the chemical potential of saturated water vapor at 298K. The threshold chemical potential is found to be sensitive to both the size of the channel and the ion species, with the anion-bearing pores filling at lower chemical potentials. Additionally, the filling threshold chemical potential is found to decrease as the radius of the pores is decreased. Pores with K+ and Cl- are compared, and the Cl- pores are found to exhibit higher water densities in the filled states and a more energetically favorable water structure while yielding lower per particle entropies. Sample simulation configurations are also examined and indicate that at low chemical potentials, the adsorbed water forms a cluster around the ion. Finally, the influence of the choice of water model on the adsorption isotherms is examined.

  10. Thermally Switchable Aligned Nanopores by Magnetic-Field Directed Self-Assembly of Block Copolymers

    Science.gov (United States)

    Osuji, Chinedum

    2014-03-01

    Magnetic fields provide a facile approach to direct the self-assembly of magnetically anisotropic block copolymer nanostructures in a scalable manner. Here we combine such field-based processing with materials design to enable the fabrication of polymer films with highly aligned stimuli-responsive nanopores. Etch removal of a poly(D,L-lactide) (PLA) brush that is the minority component of a liquid crystalline block copolymer is used to produce nanopores of ~ 8 nm diameter. The pores can be reversibly closed and opened while retaining their alignment by appropriate heating and cooling. We present TEM and temperture resolved scattering data during pore closure and re-opening to explore the mechanism and kinetics of pore collapse. NSF DMR-0847534; DMR-1119826.

  11. Oxide-based inorganic/organic and nanoporous spherical particles: synthesis and functional properties

    Science.gov (United States)

    Shiba, Kota; Tagaya, Motohiro; Tilley, Richard D.; Hanagata, Nobutaka

    2013-04-01

    This paper reviews the recent progress in the preparation of oxide-based and heteroatom-doped particles. Surfactant-templated oxide particles, e.g. silica and titania, are possible candidates for various potential applications such as adsorbents, photocatalysts, and optoelectronic and biological materials. We highlight nanoporous oxides of one element, such as silicon or titanium, and those containing multiple elements, which exhibit properties that are not achieved with individual components. Although the multicomponent nanoporous oxides possess a number of attractive functions, the origin of their properties is hard to determine due to compositional/structural complexity. Particles with a well-defined size and shape are keys for a quantitative and detailed discussion on the unique complex properties of the particles. From this viewpoint, we review the synthesis techniques of the oxide particles, which are functionalized with organic molecules or doped with heteroatoms, the physicochemical properties of the particles and the possibilities for their photofunctional applications as complex systems.

  12. Catalytic oxidation of benzene with ozone over nanoporous Mn/MCM-48 catalyst.

    Science.gov (United States)

    Park, Jong-Hwa; Jurng, Jongsoo; Bae, Gwi-Nam; Park, Sung Hoon; Jeon, Jong-Ki; Kim, Sang Chai; Kim, Ji Man; Park, Young-Kwon

    2012-07-01

    The catalytic oxidation of a representative volatile organic compound, benzene, with ozone at a low temperature was investigated. A nanoporous MCM-48 material with a high specific surface area was used as the support for the catalytic oxidation for the first time. Mn, which has high activity at a low temperature, was used as the metal catalyst. To examine the effect of the Mn precursor, MCM-48 was impregnated with two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were analyzed by Brunauer Emmett Teller surface area, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. MCM-48 impregnated with Mn acetate showed higher catalytic activity than MCM-48 impregnated with Mn nitrate. This result was attributed to the better dispersion within nanoporous MCM-48 and higher oxygen mobility of Mn oxides produced by Mn acetate. The catalytic activity was also shown to depend closely on the ozone concentration.

  13. Electrical characterization of DNA-functionalized solid state nanopores for bio-sensing

    Energy Technology Data Exchange (ETDEWEB)

    Mussi, V; Fanzio, P; Repetto, L; Firpo, G; Valbusa, U [Nanomed Labs, Physics Department, University of Genova, and Nanobiotechnologies, National Institute of Cancer Research (IST), Largo R Benzi, 10 Genova, 16132 (Italy); Scaruffi, P; Stigliani, S; Tonini, G P [Translational Pediatric Oncology, National Institute for Cancer Research (IST), Largo R Benzi, 10 Genova, 16132 (Italy); Menotta, M; Magnani, M, E-mail: mussi@fisica.unige.i [Department of Biomolecular Sciences, University of Urbino ' Carlo Bo' , Via Saffi 2, 61029 Urbino (Italy)

    2010-11-17

    We present data concerning the electrical properties of a class of biosensor devices based on bio-functionalized solid state nanopores able to detect different kinds of interactions between probe molecules, chemically attached to the pore surface, and target molecules present in solution and electrophoretically drawn through the nanometric channel. The great potentiality of this approach resides in the fact that the functionalization of a quite large pore (up to 50-60 nm) allows a sufficient diameter reduction for the attainment of a single molecule sensing dimension and selective activation, without the need for further material deposition, such as metal or oxides, or localized surface modification. The results indicate that it will be possible, in the near future, to conceive and design devices for parallel analysis of biological samples made of arrays of nanopores differently functionalized, fabricated by standard lithographic techniques, with important applications in the field of molecular diagnosis.

  14. Electrical characterization of DNA-functionalized solid state nanopores for bio-sensing

    Science.gov (United States)

    Mussi, V.; Fanzio, P.; Repetto, L.; Firpo, G.; Scaruffi, P.; Stigliani, S.; Menotta, M.; Magnani, M.; Tonini, G. P.; Valbusa, U.

    2010-11-01

    We present data concerning the electrical properties of a class of biosensor devices based on bio-functionalized solid state nanopores able to detect different kinds of interactions between probe molecules, chemically attached to the pore surface, and target molecules present in solution and electrophoretically drawn through the nanometric channel. The great potentiality of this approach resides in the fact that the functionalization of a quite large pore (up to 50-60 nm) allows a sufficient diameter reduction for the attainment of a single molecule sensing dimension and selective activation, without the need for further material deposition, such as metal or oxides, or localized surface modification. The results indicate that it will be possible, in the near future, to conceive and design devices for parallel analysis of biological samples made of arrays of nanopores differently functionalized, fabricated by standard lithographic techniques, with important applications in the field of molecular diagnosis.

  15. Electrodeposition and Characterization of Nickel, Iron, Copper Thin Films and the Creation of Nanoporous Structures

    Science.gov (United States)

    Yarranton, Jonathan; Hampton, Jennifer

    2013-03-01

    There has been much research in creating nanoporous platinum or gold thin films for catalysis, but there has not been as much work done with other, less noble metals. This research explored the deposition of nickel, iron, and copper ternary alloys using controlled potential electrolysis (CPE) and the selective removal of the copper with DC potential amperometry (DCPA) and linear sweep voltammetry (LSV) to create nanoporous structures. These structures have the advantage of increased surface area creating more efficient catalysts. All films were characterized before and after dealloying using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) for composition. The roughness of each of the films was characterized by the capacitance of the film, with higher capacitances indicating a higher electrochemical surface area. This material is based upon work supported by the National Science Foundation under RUI Grant DMR-1104725, MRI Grant CHE-0959282, and ARI grant PHY-0963317.

  16. Synthesis of nanoporous silica with interior composite cells with synthetic block copolypeptide as template

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nanoporous silica with unusual interior composite cells was synthesized with synthetic block copolypeptide Phe20-b-PBLG50 as template for the first time. Anilino-methyl triethoxy silane (AMTS) was used as an intermedium to interact with block copolypeptide Phe20-b-PBLG50 through π-π interaction between the phenyl groups of block copolypeptide and those of AMTS. Meanwhile, AMTS co-condenses together with tetraethoxylsilane (TEOS) after hydrolysis. The structure of composite vesicles due to the self-assembly of block copolypeptide in the organic solvent was immobilized and transcribed by the formation of silica. The formation of nanopores could be ascribed to the secondary structure of block copolypeptide and small molecular amine. Our results provide a new avenue to synthesize porous oxide materials with novel interior structures templated by the copolypeptide self-assembly under ambient conditions.

  17. In-situ electrochemical doping of nanoporous anodic aluminum oxide with indigo carmine organic dye

    Energy Technology Data Exchange (ETDEWEB)

    Stępniowski, Wojciech J., E-mail: wojciech.stepniowski@wat.edu.pl [Department of Advanced Materials and Technology, Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Norek, Małgorzata [Department of Advanced Materials and Technology, Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Budner, Bogusław [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Michalska-Domańska, Marta [Department of Advanced Materials and Technology, Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Nowak-Stępniowska, Agata; Bombalska, Aneta; Kaliszewski, Miron [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Mostek, Anna [Department of Advanced Materials and Technology, Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Thorat, Sanjay; Salerno, Marco [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, Genova I-16163 (Italy); Giersig, Michael [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Bojar, Zbigniew [Department of Advanced Materials and Technology, Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland)

    2016-01-01

    Nanoporous anodic aluminum oxide was formed in sulfuric acid with addition of indigo carmine. During anodizing, the organic dye was incorporated into the porous oxide walls. X-ray photoelectron spectroscopy revealed the presence of nitrogen and sulfur in the anodic aluminum oxide. Two types of incorporated sulfur were found: belonging to the sulfate anions SO{sub 4}{sup 2−} of the electrolyte and belonging to the C-SO{sub 3}{sup −} side groups of the indigo carmine. Raman spectroscopy confirmed the incorporation and showed that the inorganic–organic hybrid material inherited optical properties from the indigo carmine. Typical modes from pyrrolidone rings, unique for indigo carmine in the investigated system (650 and 1585 cm{sup −1}), were found to be the strongest for the greatest anodizing voltages used. Despite the indigo carmine incorporation, the morphology of the oxide is still nanoporous and its geometry is still tuned by the voltage applied during aluminum anodization. This work presents an inexpensive and facile approach to doping an inorganic oxide material with organic compounds. - Highlights: • Nanoporous anodic alumina was formed in electrolyte with indigo carmine. • XPS confirmed the presence of N and S in anodic alumina. • Raman spectroscopy revealed indigo carmine bands in anodic alumina. • The higher the voltage, the more indigo carmine was incorporated.

  18. Nanopore DNA sequencing and epigenetic detection with a MspA nanopore

    Science.gov (United States)

    Laszlo, Andrew H.

    DNA forms the molecular basis for all known life. Widespread DNA sequencing has the potential to revolutionize healthcare and our understanding of the life sciences. Sequencing has already had a profound effect on our understanding of the molecular basis of life and underpinnings of disease. Current DNA sequencing technologies require costly reagents, can sequence only short DNA strands, and take too long to complete entire genomes. Furthermore, the required DNA sample size limits the types of experiments that can be run. For instance sequencing single cells is extremely difficult. New technologies are key to making DNA sequencing as cheap and accessible as possible and for making new experiments possible. One such new technology is nanopore sequencing. In nanopore sequencing, a thin membrane is used to divide a salt solution into two wells: cis and trans. This membrane contains a single nanometer sized hole that forms the only electrical connection between the two wells. When a voltage is applied across the membrane, ion current flows through the nanopore. This ion current is the primary signal for nanopore sequencing. DNA is negatively charged and can be pulled into the pore. When DNA is pulled into the pore, it occludes the pore and reduces the ion current that can pass through the pore. Individual DNA nucleotides along the DNA strand block the pore to varying degrees. One can measure the degree to which the pore is blocked as DNA passes through the pore and use the ion current signal to read off the DNA sequence. This thesis chronicles recent advances in the Gundlach laboratory in which I have played a leading role. It describes our work testing the biological nanopore Mycobacterium smegmatis porin A (MspA) for nanopore sequencing. The thesis consists of five chapters and three appendices which contain supplemental information for Chapters 2, 3, and 4. Chapter 1 begins with some motivation and defines the current challenges in DNA sequencing. I also introduce

  19. Experimental method for the determination of adsorption-induced changes of pressure and surface stress in nanopores

    Science.gov (United States)

    Schappert, Klaus; Pelster, Rolf

    2017-02-01

    The change of surface stress is an important quantity characterising the behaviour of nanoporous systems, however, it is difficult to assess experimentally. In this letter we develop and demonstrate an experimental method for the determination of adsorption-induced changes of the surface stress in nanoporous materials. With the aid of ultrasonic measurements we determine the dependence of the adsorbate’s longitudinal modulus {β\\text{Ar,\\text{ads}}} on the adsorption-induced normal pressure, Δ {{p}\\text{S}} , which is exerted by the adsorbate on the porous matrix. From this dependence we deduce the normal pressure at saturation, Δ p\\text{S}\\text{sat} , and thereby changes of the surface stress {{≤ft(Δ f\\right)}\\text{sat}} at the interface between the solid matrix and the liquid adsorbate. For the model system of argon in nanoporous glass (pore radius {{r}\\text{P}}=3.8 nm) the ultrasonic method reveals a value for Δ p\\text{S}\\text{sat} that is in very good agreement with the theoretical value known for the argon-silica interface. The disclosure of this experimental method and its application on other systems will enable a better understanding of the behaviour of adsorbates in nanoporous materials.

  20. Experimental method for the determination of adsorption-induced changes of pressure and surface stress in nanopores.

    Science.gov (United States)

    Schappert, Klaus; Pelster, Rolf

    2017-02-15

    The change of surface stress is an important quantity characterising the behaviour of nanoporous systems, however, it is difficult to assess experimentally. In this letter we develop and demonstrate an experimental method for the determination of adsorption-induced changes of the surface stress in nanoporous materials. With the aid of ultrasonic measurements we determine the dependence of the adsorbate's longitudinal modulus [Formula: see text] on the adsorption-induced normal pressure, [Formula: see text], which is exerted by the adsorbate on the porous matrix. From this dependence we deduce the normal pressure at saturation, [Formula: see text], and thereby changes of the surface stress [Formula: see text] at the interface between the solid matrix and the liquid adsorbate. For the model system of argon in nanoporous glass (pore radius [Formula: see text] nm) the ultrasonic method reveals a value for [Formula: see text] that is in very good agreement with the theoretical value known for the argon-silica interface. The disclosure of this experimental method and its application on other systems will enable a better understanding of the behaviour of adsorbates in nanoporous materials.

  1. Single Nanoparticle Translocation Through Chemically Modified Solid Nanopore

    Science.gov (United States)

    Tan, Shengwei; Wang, Lei; Liu, Hang; Wu, Hongwen; Liu, Quanjun

    2016-02-01

    The nanopore sensor as a high-throughput and low-cost technology can detect single nanoparticle in solution. In the present study, the silicon nitride nanopores were fabricated by focused Ga ion beam (FIB), and the surface was functionalized with 3-aminopropyltriethoxysilane to change its surface charge density. The positively charged nanopore surface attracted negatively charged nanoparticles when they were in the vicinity of the nanopore. And, nanoparticle translocation speed was slowed down to obtain a clear and deterministic signal. Compared with previous studied small nanoparticles, the electrophoretic translocation of negatively charged polystyrene (PS) nanoparticles (diameter ~100 nm) was investigated in solution using the Coulter counter principle in which the time-dependent nanopore current was recorded as the nanoparticles were driven across the nanopore. A linear dependence was found between current drop and biased voltage. An exponentially decaying function ( t d ~ e -v/v0 ) was found between the duration time and biased voltage. The interaction between the amine-functionalized nanopore wall and PS microspheres was discussed while translating PS microspheres. We explored also translocations of PS microspheres through amine-functionalized solid-state nanopores by varying the solution pH (5.4, 7.0, and 10.0) with 0.02 M potassium chloride (KCl). Surface functionalization showed to provide a useful step to fine-tune the surface property, which can selectively transport molecules or particles. This approach is likely to be applied to gene sequencing.

  2. Effect of flow rate on diameter of electrospun nanoporous fibers

    Directory of Open Access Journals (Sweden)

    Tang Xiao-Peng

    2014-01-01

    Full Text Available The effect of flow rate on the diameter of the charged jet in the electrospinning process is studied theoretically. The obtained theoretical results offer in-depth physical understanding and mechanism of nanoporous fibers. It also reveals that the morphology and diameter of nanoporous microspheres can be controlled by the flow rate.

  3. UV patterned nanoporous solid-liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Sagar, Kaushal Shashikant; Christiansen, Mads Brøkner;

    2010-01-01

    Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (delta n = 0.20) is a result of selective water infiltration. The waveguide core is defined by UV light, rendering the exposed part...

  4. Nanoparticle mechanics: deformation detection via nanopore resistive pulse sensing

    Science.gov (United States)

    Darvish, Armin; Goyal, Gaurav; Aneja, Rachna; Sundaram, Ramalingam V. K.; Lee, Kidan; Ahn, Chi Won; Kim, Ki-Bum; Vlahovska, Petia M.; Kim, Min Jun

    2016-07-01

    Solid-state nanopores have been widely used in the past for single-particle analysis of nanoparticles, liposomes, exosomes and viruses. The shape of soft particles, particularly liposomes with a bilayer membrane, can greatly differ inside the nanopore compared to bulk solution as the electric field inside the nanopores can cause liposome electrodeformation. Such deformations can compromise size measurement and characterization of particles, but are often neglected in nanopore resistive pulse sensing. In this paper, we investigated the deformation of various liposomes inside nanopores. We observed a significant difference in resistive pulse characteristics between soft liposomes and rigid polystyrene nanoparticles especially at higher applied voltages. We used theoretical simulations to demonstrate that the difference can be explained by shape deformation of liposomes as they translocate through the nanopores. Comparing our results with the findings from electrodeformation experiments, we demonstrated that the rigidity of liposomes can be qualitatively compared using resistive pulse characteristics. This application of nanopores can provide new opportunities to study the mechanics at the nanoscale, to investigate properties of great value in fundamental biophysics and cellular mechanobiology, such as virus deformability and fusogenicity, and in applied sciences for designing novel drug/gene delivery systems.Solid-state nanopores have been widely used in the past for single-particle analysis of nanoparticles, liposomes, exosomes and viruses. The shape of soft particles, particularly liposomes with a bilayer membrane, can greatly differ inside the nanopore compared to bulk solution as the electric field inside the nanopores can cause liposome electrodeformation. Such deformations can compromise size measurement and characterization of particles, but are often neglected in nanopore resistive pulse sensing. In this paper, we investigated the deformation of various

  5. DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Lueking, Angela D.; Li, Qixiu; Badding, John V.; Fonseca, Dania; Gutierrez, Humerto; Sakti, Apurba; Adu, Kofi; Schimmel, Michael

    2010-03-31

    Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

  6. Nanopore formation in neuroblastoma cells following ultrashort electric pulse exposure

    Science.gov (United States)

    Roth, Caleb C.; Payne, Jason A.; Wilmink, Gerald J.; Ibey, Bennett L.

    2011-03-01

    Ultrashort or nanosecond electrical pulses (USEP) cause repairable damage to the plasma membranes of cells through formation of nanopores. These nanopores are able to pass small ions such as sodium, calcium, and potassium, but remain impermeable to larger molecules like trypan blue and propidium iodide. What remains uncertain is whether generation of nanopores by ultrashort electrical pulses can inhibit action potentials in excitable cells. In this paper, we explored the sensitivity of excitable cells to USEP using Calcium Green AM 1 ester fluorescence to measure calcium uptake indicative of nanopore formation in the plasma membrane. We determined the threshold for nanopore formation in neuroblastoma cells for three pulse parameters (amplitude, pulse width, and pulse number). Measurement of such thresholds will guide future studies to determine if USEP can inhibit action potentials without causing irreversible membrane damage.

  7. A Protein Nanopore-Based Approach for Bacteria Sensing

    Science.gov (United States)

    Apetrei, Aurelia; Ciuca, Andrei; Lee, Jong-kook; Seo, Chang Ho; Park, Yoonkyung; Luchian, Tudor

    2016-11-01

    We present herein a first proof of concept demonstrating the potential of a protein nanopore-based technique for real-time detection of selected Gram-negative bacteria ( Pseudomonas aeruginosa or Escherichia coli) at a concentration of 1.2 × 108 cfu/mL. The anionic charge on the bacterial outer membrane promotes the electrophoretically driven migration of bacteria towards a single α-hemolysin nanopore isolated in a lipid bilayer, clamped at a negative electric potential, and followed by capture at the nanopore's mouth, which we found to be described according to the classical Kramers' theory. By using a specific antimicrobial peptide as a putative molecular biorecognition element for the bacteria used herein, we suggest that the detection system can combine the natural sensitivity of the nanopore-based sensing techniques with selective biological recognition, in aqueous samples, and highlight the feasibility of the nanopore-based platform to provide portable, sensitive analysis and monitoring of bacterial pathogens.

  8. 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.

  9. Integrated solid-state nanopore platform for nanopore fabrication via dielectric breakdown, DNA-speed deceleration and noise reduction

    Science.gov (United States)

    Goto, Yusuke; Yanagi, Itaru; Matsui, Kazuma; Yokoi, Takahide; Takeda, Ken-Ichi

    2016-08-01

    The practical use of solid-state nanopores for DNA sequencing requires easy fabrication of the nanopores, reduction of the DNA movement speed and reduction of the ionic current noise. Here, we report an integrated nanopore platform with a nanobead structure that decelerates DNA movement and an insulating polyimide layer that reduces noise. To enable rapid nanopore fabrication, we introduced a controlled dielectric breakdown (CDB) process into our system. DNA translocation experiments revealed that single nanopores were created by the CDB process without sacrificing performance in reducing DNA movement speed by up to 10 μs/base or reducing noise up to 600 pArms at 1 MHz. Our platform provides the essential components for proceeding to the next step in the process of DNA sequencing.

  10. Electrodeposition of nanoporous ZnO on Al-doped ZnO leading to a highly organized structure for integration in Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Renou G.

    2010-10-01

    Full Text Available In the present study, we propose an improvement of the anode configuration in Zinc Oxide based Dye Sensitized Solar Cells (DSSC. Instead of the classical configuration, which is composed by two different metal oxides: one transparent conducting oxide (TCO for the substrate and one nanostructured metal oxide for supporting the dye, the new approach is to use ZnO as unique material. Thus, nanoporous zinc oxide films have been electrodeposited on a sputtered Al doped ZnO layers with varying thicknesses up to 6 μm. The evolution of the porosity of the structure has been studied by scanning electron microscope (SEM and electrochemical impedance spectroscopy and compared with standard nanoporous ZnO grown on fluorine doped tin oxide (SnO2:F noted FTO. This results firstly in the modification of the nanoporous structure morphology and secondly a better adhesion between the nanoporous layer and the substrate. Organization in the nanoporous material is enhanced with regular pores arrays and perpendicular to the substrate. Dye sensitized solar cells based on this simplified architecture present efficiencies up to 4.2% and 4.5% with N719 and D149 respectively as sensitizers. Higher fill factor and Voc are found in comparison with the one obtained for deposition on the classical transparent conducting oxide (FTO, which denote improved electrical transfer properties.

  11. Achieving enhanced ionic mobility in nanoporous silica by controlled surface interactions.

    Science.gov (United States)

    Garaga, Mounesha Nagendrachar; Aguilera, Luis; Yaghini, Negin; Matic, Aleksandar; Persson, Michael; Martinelli, Anna

    2017-02-22

    We report a strategy to enhance the ionic mobility in an emerging class of gels, based on robust nanoporous silica micro-particles, by chemical functionalization of the silica surface. Two very different ionic liquids are used to fill the nano-pores of silica at varying pore filling factors, namely one aprotic imidazolium based (1-methyl-3-hexylimidazolium bis(trifluoromethanesulfonyl)imide, C6C1ImTFSI), and one protic ammonium based (diethylmethylammonium methanesulfonate, DEMAOMs) ionic liquid. Both these ionic liquids display higher ionic mobility when confined in functionalized silica as compared to untreated silica nano-pores, an improvement that is more pronounced at low pore filling factors (i.e. in the nano-sized pore domains) and observed in the whole temperature window investigated (i.e. from -10 to 140 °C). Solid-state NMR, diffusion NMR and dielectric spectroscopy concomitantly demonstrate this effect. The origin of this enhancement is explained in terms of weaker intermolecular interactions and a consequent flipped-ion effect at the silica interface strongly supported by 2D solid-state NMR experiments. The possibility to significantly enhance the ionic mobility by controlling the nature of surface interactions is extremely important in the field of materials science and highlights these structurally tunable gels as promising solid-like electrolytes for use in energy relevant devices. These include, but are not limited to, Li-ion batteries and proton exchange membrane (PEM) fuel cells.

  12. Designing robust alumina nanowires-on-nanopores structures: superhydrophobic surfaces with slippery or sticky water adhesion.

    Science.gov (United States)

    Peng, Shan; Tian, Dong; Miao, Xinrui; Yang, Xiaojun; Deng, Wenli

    2013-11-01

    Hierarchical alumina surfaces with different morphologies were fabricated by a simple one-step anodization method. These alumina films were fabricated by a new raw material: silica gel plate (aluminum foil with a low purity of 97.17%). The modulation of anodizing time enabled the formation of nanowires-on-nanopores hybrid nanostructures having controllable nanowires topographies through a self-assembly process. The resultant structures were demonstrated to be able to achieve superhydrophobicity without any hydrophobic coating layer. More interestingly, it is found that the as-prepared superhydrophobic alumina surfaces exhibited high contrast water adhesion. Hierarchical alumina film with nanowire bunches-on-nanopores (WBOP) morphology presents extremely slippery property which can obtain a sliding angle (SA) as low as 1°, nanowire pyramids-on-nanopores (WPOP) structure shows strongly sticky water adhesion with the adhesive ability to support 15 μL inverted water droplet at most. The obtained superhydrophobic alumina surfaces show remarkable mechanical durability even treated by crimping or pressing without impact on the water-repellent performance. Moreover, the created surfaces also show excellent resistivity to ice water, boiling water, high temperature, organic solvent and oil contamination, which could expand their usefulness and efficacy in harsh conditions.

  13. Photoluminescent properties of di(8-hydroxyquinolato) zinc impregnated in nanoporous glass

    Institute of Scientific and Technical Information of China (English)

    Dayuan Xiong(熊大元); Yuyan Liu(刘煜炎); Suihua Yuan(袁绥华)

    2004-01-01

    Photoluminescent properties of a metal-organic complex, di(8-hydroxyquinolato) zinc, impregnated in nanoporous glass were investigated. In comparison with those in the normal organic fluorescent material,the emission band of the impregnated organic phosphor became wider. Blueshift (14 nm) was observed due to π* → n emission transition. The excitation band of the embedded organic phosphor had a larger blueshift and was divided into several sub-bands. The intensity in the short wavelength end of the embedded organic fluorescent material became much stronger.

  14. Computational Study of Porous Materials for Gas Separations

    OpenAIRE

    Lin, Li-Chiang

    2014-01-01

    Nanoporous materials such as zeolites, zeolitic imidazolate frameworks (ZIFs), and metal-organic frameworks (MOFs) are used as sorbents or membranes for gas separations such as carbon dioxide capture, methane capture, paraffin/olefin separations, etc. The total number of nanoporous materials is large; by changing the chemical composition and/or the structural topologies we can envision an infinite number of possible materials. In practice one can synthesize and fully characterize only a small...

  15. Constructing nanoporous carbon nanotubes/Bi2Te3 composite for synchronous regulation of the electrical and thermal performances

    Science.gov (United States)

    Zhang, Qihao; Xu, Leilei; Zhou, Zhenxing; Wang, Lianjun; Jiang, Wan; Chen, Lidong

    2017-02-01

    Porous nanograined thermoelectric materials exhibit low thermal conductivity due to scattering of phonons by pores, which are favorable for thermoelectric applications. However, the benefit is not large enough to overcome the deficiency in the electrical performance. Herein, an approach is presented to reduce the thermal conductivity and synchronously enhance the electrical conductivity through constructing a nanoporous thermoelectric composite. Carbon nanotubes (CNTs) are truncated and homogeneously dispersed within the Bi2Te3 matrix by a cryogenic grinding (CG) technique for the first time, which efficiently suppress the Bi2Te3 grain growth and create nanopores with the size ranging from dozens to hundreds of nanometers. The lattice thermal conductivity is substantially decreased by broad wavelength phonon scattering resulting from nanopores, increased grain boundaries, and newly formed interfaces. Meanwhile, the electrical conductivity is improved due to the enhanced carrier mobility, which may originate from the bridging effect between the Bi2Te3 grains and CNTs. The maximum ZT is improved by almost a factor of 2 due to the simultaneous optimization of electrical and thermal performances. Our study demonstrates the superiority of constructing a bulk thermoelectric composite with nanopores by the uniform dispersion of CNTs through a CG technique for enhanced thermoelectric properties, which provides a wider approach to thermoelectric nanostructure engineering.

  16. Nanoporous Mo2C functionalized 3D carbon architecture anode for boosting flavins mediated interfacial bioelectrocatalysis in microbial fuel cells

    Science.gov (United States)

    Zou, Long; Lu, Zhisong; Huang, Yunhong; Long, Zhong-er; Qiao, Yan

    2017-08-01

    An efficient microbial electrocatalysis in microbial fuel cells (MFCs) needs both high loading of microbes (biocatalysts) and robust interfacial electron transfer from microbes to electrode. Herein a nanoporous molybdenum carbide (Mo2C) functionalized carbon felt electrode with rich 3D hierarchical porous architecture is applied as MFC anode to achieve superior electrocatalytic performance. The nanoporous Mo2C functionalized anode exhibits strikingly improved microbial electrocatalysis in MFCs with 5-fold higher power density and long-term stability of electricity production. The great enhancement is attributed to the introduction of rough Mo2C nanostructural interface into macroporous carbon architecture for promoting microbial growth with great excretion of endogenous electron shuttles (flavins) and rich available nanopores for enlarging electrochemically active surface area. Importantly, the nanoporous Mo2C functionalized anode is revealed for the first time to have unique electrocatalytic activity towards redox reaction of flavins with more negative redox potential, indicating a more favourable thermodynamic driving force for anodic electron transfer. This work not only provides a promising electrode for high performance MFCs but also brings up a new insight into the effect of nanostructured materials on interfacial bioelectrocatalysis.

  17. Swelling, Functionalization, and Structural Changes of the Nanoporous Layered Silicates AMH-3 and MCM-22

    KAUST Repository

    Kim, Wun-gwi

    2011-06-21

    Nanoporous layered silicate materials contain 2D-planar sheets of nanoscopic thickness and ordered porous structure. In comparison to porous 3D-framework materials such as zeolites, they have advantages such as significantly increased surface area and decreased diffusion limitations because the layers can potentially be exfoliated or intercalated into polymers to form nanocomposite materials. These properties are particularly interesting for applications as materials for enhancing molecular selectivity and throughput in composite membranes. In this report, the swelling and surface modification chemistry of two attractive nanoporous layered silicate materials, AMH-3 and MCM-22, were studied. We first describe a method, using long-chain diamines instead of monoamines, for swelling of AMH-3 while preserving its pore structure to a greater extent during the swelling process. Then, we describe a stepwise functionalization method for functionalizing the layer surfaces of AMH-3 and MCM-22 via silane condensation reactions. The covalently attached hydrocarbon chain molecules increased the hydrophobicity of AMH-3 and MCM-22 layer surfaces and therefore allow the possibility of effectively dispersing these materials in polymer matrices for thin film/membrane applications. © 2011 American Chemical Society.

  18. Functionalized Nanoporous Silica for Removal of Heavy Metals from Biological Systems; Adsorption and Application

    Energy Technology Data Exchange (ETDEWEB)

    Yantasee, Wassana; Rutledge, Ryan D.; Chouyyok, Wilaiwan; Sukwarotwat, Vichaya; Orr, Galya; Warner, Cynthia L.; Warner, Marvin G.; Fryxell, Glen E.; Wiacek, Robert J.; Timchalk, Charles; Addleman, Raymond S.

    2010-10-01

    Functionalized nanoporous silica, often referred to as self-assembled monolayers on mesoporous supports (SAMMS) have previously demonstrated the ability to serve as very effective heavy metal sorbents in a range of aquatic and environmental systems suggesting they may be advantageously utilized for biomedical applications such as chelation therapy. Herein we evaluate surface chemistries for heavy metal capture from biological fluids, various facets of the materials biocompatibility and the suitability of these materials as potential therapeutics. Of the materials tested, thiol-functionalized SAMMS proved most capable of removing selected heavy metals from biological solutions (i.e. blood, urine, etc.) As a result, thiol SAMMS was further analyzed to assess the material’s performance under a number of different biologically relevant conditions (i.e. variable pH and ionic strength) as well to gauge any potentially negative cellular effects resulting from interaction with the sorbent, such as cellular toxicity or possible chelation of essential minerals. Additionally, cellular uptake studies demonstrated no cell membrane permeation by the silica-based materials generally highlighting their ability to remain cellularly inert and thus non-toxic. As a result, it has been determined that organic ligand-functionalized nanoporous silica materials could be a valuable material for detoxification therapeutics and potentially other biomedical applications as needed.

  19. Functionalized nanoporous silica for the removal of heavy metals from biological systems: adsorption and application.

    Science.gov (United States)

    Yantasee, Wassana; Rutledge, Ryan D; Chouyyok, Wilaiwan; Sukwarotwat, Vichaya; Orr, Galya; Warner, Cynthia L; Warner, Marvin G; Fryxell, Glen E; Wiacek, Robert J; Timchalk, Charles; Addleman, R Shane

    2010-10-01

    Surface-functionalized nanoporous silica, often referred to as self-assembled monolayers on mesoporous supports (SAMMS), has previously demonstrated the ability to serve as very effective heavy metal sorbents in a range of aquatic and environmental systems, suggesting that they may be advantageously utilized for biomedical applications such as chelation therapy. Herein we evaluate surface chemistries for heavy metal capture from biological fluids, various facets of the materials' biocompatibility, and the suitability of these materials as potential therapeutics. Of the materials tested, thiol-functionalized SAMMS proved most capable of removing selected heavy metals from biological solutions (i.e., blood, urine, etc.) Consequentially, thiol-functionalized SAMMS was further analyzed to assess the material's performance under a number of different biologically relevant conditions (i.e., variable pH and ionic strength) to gauge any potentially negative effects resulting from interaction with the sorbent, such as cellular toxicity or the removal of essential minerals. Additionally, cellular uptake studies demonstrated no cell membrane permeation by the silica-based materials generally highlighting their ability to remain cellularly inert and thus nontoxic. The results show that organic ligand functionalized nanoporous silica could be a valuable material for a range of detoxification therapies and potentially other biomedical applications.

  20. Super-sensitive Molecule-hugging Graphene Nanopores

    CERN Document Server

    Garaj, Slaven; Branton, Daniel; Golovchenko, Jene A

    2012-01-01

    Longitudinal resolution and lateral sensitivity are decisive characteristics that determine the suitability of a nanopore sensor for sequencing a strand of DNA as well as other important polymers. Previous modeling of DNA induced ionic current blockades in single atom thick graphene nanopores has shown these nanopores to have sufficient longitudinal resolution to distinguish individual nucleobases along the length of a DNA molecule. Here we experimentally focus on the sensitivity to small changes in DNA diameter that can be discerned with graphene nanopores. We show that remarkably large sensitivities (0.5 nA/A)are obtained when the nanopore is tailored to have a diameter close to that of the polymer of interest. Our results have been obtained with double-stranded DNA (dsDNA). Smaller graphene nanopores that can be tuned to the diameter of single-stranded DNA (ssDNA) for sequencing have only recently been demonstrated. Our results indicate that nanopore sensors based on such pores will provide excellent resol...

  1. 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.

  2. Nanoporous carbon actuator and methods of use thereof

    Science.gov (United States)

    Biener, Juergen [San Leandro, CA; Baumann, Theodore F [Discovery Bay, CA; Shao, Lihua [Karlsruhe, DE; Weissmueller, Joerg [Stutensee, DE

    2012-07-31

    An electrochemically driveable actuator according to one embodiment includes a nanoporous carbon aerogel composition capable of exhibiting charge-induced reversible strain when wetted by an electrolyte and a voltage is applied thereto. An electrochemically driven actuator according to another embodiment includes a nanoporous carbon aerogel composition wetted by an electrolyte; and a mechanism for causing charge-induced reversible strain of the composition. A method for electrochemically actuating an object according to one embodiment includes causing charge-induced reversible strain of a nanoporous carbon aerogel composition wetted with an electrolyte to actuate the object by the strain.

  3. Nanoporous hard data: optical encoding of information within nanoporous anodic alumina photonic crystals

    Science.gov (United States)

    Santos, Abel; Law, Cheryl Suwen; Pereira, Taj; Losic, Dusan

    2016-04-01

    Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for developing advanced nanophotonic tools for a wide range of applications, including sensing, photonic tagging, self-reporting drug releasing systems and secure encoding of information.Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for

  4. Thermal characterization of nanoporous 'black silicon' surfaces

    Science.gov (United States)

    Nichols, Logan; Duan, Wenqi; Toor, Fatima

    2016-09-01

    In this work we characterize the thermal conductivity properties of nanoprous `black silicon' (bSi). We fabricate the nanoporous bSi using the metal assisted chemical etching (MACE) process utilizing silver (Ag) metal as the etch catalyst. The MACE process steps include (i) electroless deposition of Ag nanoparticles on the Si surface using silver nitrate (AgNO3) and hydrofluoric acid (HF), and (ii) a wet etch in a solution of HF and hydrogen peroxide (H2O2). The resulting porosity of bSi is dependent on the ratio of the concentration of HF to (HF + H2O2); the ratio is denoted as rho (ρ). We find that as etch time of bSi increases the thermal conductivity of Si increases as well. We also analyze the absorption of the bSi samples by measuring the transmission and reflection using IR spectroscopy. This study enables improved understanding of nanoporous bSi surfaces and how they affect the solar cell performance due to the porous structures' thermal properties.

  5. Gate manipulation of DNA capture into nanopores.

    Science.gov (United States)

    He, Yuhui; Tsutsui, Makusu; Fan, Chun; Taniguchi, Masateru; Kawai, Tomoji

    2011-10-25

    Understanding biophysics governing DNA capture into a nanopore and establishing a manipulation system for the capture process are essential for nanopore-based genome sequencing. In this work, the functionality of extended electric field and electroosmotic flow (EOF) during the capture stage and their dependence on gate voltage, U(G), are investigated. We demonstrate that while both the electric field and EOF within a cis chamber make long-distance contributions to DNA capture around the pore mouth, the former effect is always capturing, while the latter causes trapping or blocking of the molecule depending on the magnitude of the gate voltage, U(G): an anionic EOF induced by high U(G) is capable of doubling the DNA trapping speed and thus the absorption radius in the cis chamber, whereas a cationic EOF by low U(G) would substantially offset the trapping effort by the electric field and even totally block DNA entrance into the pore. Based on the analysis, a gate regulation is proposed with the objective of achieving a high DNA capture rate while maintaining a low error rate.

  6. Capturing CO2 via reactions in nanopores.

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Kevin; Nenoff, Tina Maria; Criscenti, Louise Jacqueline; Tang, Z; Dong, J. H.

    2008-10-01

    This one-year exploratory LDRD aims to provide fundamental understanding of the mechanism of CO2 scrubbing platforms that will reduce green house gas emission and mitigate the effect of climate change. The project builds on the team members expertise developed in previous LDRD projects to study the capture or preferential retention of CO2 in nanoporous membranes and on metal oxide surfaces. We apply Density Functional Theory and ab initio molecular dynamics techniques to model the binding of CO2 on MgO and CaO (100) surfaces and inside water-filled, amine group functionalized silica nanopores. The results elucidate the mechanisms of CO2 trapping and clarify some confusion in the literature. Our work identifies key future calculations that will have the greatest impact on CO2 capture technologies, and provides guidance to science-based design of platforms that can separate the green house gas CO2 from power plant exhaust or even from the atmosphere. Experimentally, we modify commercial MFI zeolite membranes and find that they preferentially transmit H2 over CO2 by a factor of 34. Since zeolite has potential catalytic capability to crack hydrocarbons into CO2 and H2, this finding paves the way for zeolite membranes that can convert biofuel into H2 and separate the products all in one step.

  7. Graphene nanopores as negative differential resistance devices

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Wanzhi; Nguyen, Phuong Duc; Skafidas, Efstratios, E-mail: sskaf@unimelb.edu.au [Centre for Neural Engineering, The University of Melbourne, 203 Bouverie Street, Carlton, Victoria 3053, Australia and Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville, Victoria 3010 (Australia)

    2015-02-07

    We present graphene nanopores as new negative differential resistance (NDR) devices, and study their quantum transport properties using non-equilibrium Green's function and the density functional tight binding method. The proposed device structure is created on intrinsic armchair-edged graphene nanoribbons with uniform widths, where the central scattering region has a nanopore in the interior, and the two ends of the nanoribbon act naturally as connecting electrodes. We show that nitrogen-passivated scattering regions generally result in pronounced NDR properties, while hydrogen-passivated ones do not. This NDR effect occurs at low bias voltages, below 1 V, and achieves extraordinarily high peak-to-valley current ratio, while still attaining very high peak current densities. In addition, very sharp current peaks in the μA range can occur in the I-V curves, and through varying structural dimensions of the proposed structure multiple NDR regions can be realized. These results suggest that the device has promising potential in applications such as high frequency oscillators, memory devices, and fast switches.

  8. Chain-like molecules confined in nanopores

    Science.gov (United States)

    Huber, Patrick; Soprunyuk, Viktor; Hofmann, Tommy; Knorr, Klaus

    2004-03-01

    We present an x-ray diffraction study on chain-like molecules, i.e. a selection of n-alkane molecules, embedded in the pores of nanoporous silica matrices. The lengths of the hydrocarbon chains are comparable to the mean diameter ( 7nm) of the tubular like nanopores which leads to drastic geometric restrictions. Diffraction patterns, recorded on heating and cooling between 200 K and 310 K, elucidate how the structure and phase behavior of the molecules is affected by the random substrate disorder and the confinement. The confined n-alkanes form close-packed structures by aligning parallel to the pore axis. In the case of the medium-length hydrocarbon chains one basic ordering principle known from the bulk crystalline state, i.e. the lamellar ordering of the molecules, is quenched[1], whereas for shorter n-alkanes this ordering principle survives[2]. The confined solids mimic the orientational order-disorder transitions known from the 3D unconfined crystals albeit in a modified fashion. 1. P. Huber, D. Wallacher, J. Albers, K. Knorr, Europhysics Letters, in press; 2. P. Huber, D. Wallacher, J. Albers, K. Knorr, Journal of Physics: Condensed Matter 15, 309 (2003).

  9. Nanoporous carbide-derived carbon with tunable pore size

    Science.gov (United States)

    Gogotsi, Yury; Nikitin, Alexei; Ye, Haihui; Zhou, Wei; Fischer, John E.; Yi, Bo; Foley, Henry C.; Barsoum, Michel W.

    2003-09-01

    Porous solids are of great technological importance due to their ability to interact with gases and liquids not only at the surface, but throughout their bulk. Although large pores can be produced and well controlled in a variety of materials, nanopores in the range of 2 nm and below (micropores, according to IUPAC classification) are usually achieved only in carbons or zeolites. To date, major efforts in the field of porous materials have been directed towards control of the size, shape and uniformity of the pores. Here we demonstrate that porosity of carbide-derived carbons (CDCs) can be tuned with subångström accuracy in a wide range by controlling the chlorination temperature. CDC produced from Ti3SiC2 has a narrower pore-size distribution than single-wall carbon nanotubes or activated carbons; its pore-size distribution is comparable to that of zeolites. CDCs are produced at temperatures from 200-1,200 °C as a powder, a coating, a membrane or parts with near-final shapes, with or without mesopores. They can find applications in molecular sieves, gas storage, catalysts, adsorbents, battery electrodes, supercapacitors, water/air filters and medical devices.

  10. Scale-dependent diffusion anisotropy in nanoporous silicon

    Science.gov (United States)

    Kondrashova, Daria; Lauerer, Alexander; Mehlhorn, Dirk; Jobic, Hervé; Feldhoff, Armin; Thommes, Matthias; Chakraborty, Dipanjan; Gommes, Cedric; Zecevic, Jovana; de Jongh, Petra; Bunde, Armin; Kärger, Jörg; Valiullin, Rustem

    2017-01-01

    Nanoporous silicon produced by electrochemical etching of highly B-doped p-type silicon wafers can be prepared with tubular pores imbedded in a silicon matrix. Such materials have found many technological applications and provide a useful model system for studying phase transitions under confinement. This paper reports a joint experimental and simulation study of diffusion in such materials, covering displacements from molecular dimensions up to tens of micrometers with carefully selected probe molecules. In addition to mass transfer through the channels, diffusion (at much smaller rates) is also found to occur in directions perpendicular to the channels, thus providing clear evidence of connectivity. With increasing displacements, propagation in both axial and transversal directions is progressively retarded, suggesting a scale-dependent, hierarchical distribution of transport resistances (“constrictions” in the channels) and of shortcuts (connecting “bridges”) between adjacent channels. The experimental evidence from these studies is confirmed by molecular dynamics (MD) simulation in the range of atomistic displacements and rationalized with a simple model of statistically distributed “constrictions” and “bridges” for displacements in the micrometer range via dynamic Monte Carlo (DMC) simulation. Both ranges are demonstrated to be mutually transferrable by DMC simulations based on the pore space topology determined by electron tomography.

  11. Electrically tunable pore morphology in nanoporous gold thin films

    Institute of Scientific and Technical Information of China (English)

    Tatiana S. Dorofeeva; Erkin Seker

    2015-01-01

    Nanoporous gold (np-Au) is an emerging nanostructured material that exhibits many desirable properties, including high electrical and thermal conductivity, high surface area-to-volume ratio, tunable pore morphology well-established surface-binding chemistry, and compatibility with microfabrication. These features make np-Au a popular material for use in fuel cells, optical and electrical biosensors, drug delivery vehicles, neural electrode coatings, and as a model system for nanoscale mechanics. In each of its many applications, np-Au morphology plays an essential role in the overall device operation. Therefore, precise morphological control is necessary to attain optimal device performance. Traditionally thermal treatment by furnaces and hot plates is used to obtain np-Au with self-similar but coarser morphologies. However, this approach lacks the ability to create different morphologies on a single substrate and requires high temperatures (〉 250 ℃) incompatible with most plastic substrates. Herein, we report electro-annealing as a novel method that permits control of the extent and location of pore coarsening on a single substrate in one fast treatment step. The electro-annealing entails much lower temperatures (〈 150 ℃) than traditional thermal treatment, putatively due to electrically assisted phenomena contributing to the thermally activated surface diffusion of gold atoms, responsible for coarsening. Overall, this approach is easily scaled to display multiple pore morphologies on a single chip, therefore enabling high-throughput screening of optimal nanostructures for specific applications.

  12. Potential-dependent dynamic fracture of nanoporous gold

    Science.gov (United States)

    Sun, Shaofeng; Chen, Xiying; Badwe, Nilesh; Sieradzki, Karl

    2015-09-01

    When metallic alloys are exposed to a corrosive environment, porous nanoscale morphologies spontaneously form that can adversely affect the mechanical integrity of engineered structures. This form of stress-corrosion cracking is responsible for the well-known `season cracking’ of brass and stainless steel components in nuclear power generating stations. One explanation for this is that a high-speed crack is nucleated within the porous layer, which subsequently injects into non-porous parent-phase material. We study the static and dynamic fracture properties of free-standing monolithic nanoporous gold as a function electrochemical potential using high-speed photography and digital image correlation. The experiments reveal that at electrochemical potentials typical of porosity formation these structures are capable of supporting dislocation-mediated plastic fracture at crack velocities of 200 m s-1. Our results identify the important role of high-speed fracture in stress-corrosion cracking and are directly applicable to the behaviour of monolithic dealloyed materials at present being considered for a variety of applications.

  13. Graphene nanopore with a self-integrated optical antenna.

    Science.gov (United States)

    Nam, SungWoo; Choi, Inhee; Fu, Chi-cheng; Kim, Kwanpyo; Hong, SoonGweon; Choi, Yeonho; Zettl, Alex; Lee, Luke P

    2014-10-08

    We report graphene nanopores with integrated optical antennae. We demonstrate that a nanometer-sized heated spot created by photon-to-heat conversion of a gold nanorod resting on a graphene membrane forms a nanoscale pore with a self-integrated optical antenna in a single step. The distinct plasmonic traits of metal nanoparticles, which have a unique capability to concentrate light into nanoscale regions, yield the significant advantage of parallel nanopore fabrication compared to the conventional sequential process using an electron beam. Tunability of both the nanopore dimensions and the optical characteristics of plasmonic nanoantennae are further achieved. Finally, the key optical function of our self-integrated optical antenna on the vicinity of graphene nanopore is manifested by multifold fluorescent signal enhancement during DNA translocation.

  14. Nanoporous CuS with excellent photocatalytic property

    Science.gov (United States)

    Xu, Wence; Zhu, Shengli; Liang, Yanqin; Li, Zhaoyang; Cui, Zhenduo; Yang, Xianjin; Inoue, Akihisa

    2015-12-01

    We present the rational synthesis of nanoporous CuS for the first time by chemical dealloying method. The morphologies of the CuS catalysts are controlled by the composition of the original amorphous alloys. Nanoporous Cu2S is firstly formed during the chemical dealloying process, and then the Cu2S transforms into CuS. The nanoporous CuS exhibits excellent photocatalytic activity for the degradation of the methylene blue (MB), methyl orange (MO) and rhodamine B (RhB). The excellent photocatalytic activity of the nanoporous CuS is mainly attributed to the large specific surface area, high adsorbing capacity of dyes and low recombination of the photo generated electrons and holes. In the photo degradation process, both chemical and photo generated hydroxyl radicals are generated. The hydroxyl radicals are favor in the oxidation of the dye molecules. The present modified dealloying method may be extended for the preparation of other porous metal sulfide nanostructures.

  15. Bivalent ion transport through graphene/PET nanopore

    Science.gov (United States)

    Yao, Huijun; Cheng, Yaxiong; Zeng, Jian; Mo, Dan; Duan, Jinglai; Liu, Jiande; Zhai, Pengfei; Sun, Youmei; Liu, Jie

    2016-05-01

    The PET suspended single graphene nanopore (G/PET) was produced by heavy ion irradiation and asymmetric chemical etching. The solutions of NiSO4, NiCl2, CuSO4 and CuCl2 with different concentration were adopted to study the transport properties of bivalent ion in single G/PET nanopore by measuring the I-V curves. The perfect "diode effect" and excellent rectification effect of G/PET nanopore were observed, and the huge rectification ratio up to 43.3 was obtained in NiSO4 solution. The great solution selectivity and ion current magnification effect of graphene/PET nanopore were also confirmed in our study.

  16. Side-gated ultrathin-channel nanopore FET sensors.

    Science.gov (United States)

    Yanagi, Itaru; Oura, Takeshi; Haga, Takanobu; Ando, Masahiko; Yamamoto, Jiro; Mine, Toshiyuki; Ishida, Takeshi; Hatano, Toshiyuki; Akahori, Rena; Yokoi, Takahide; Anazawa, Takashi

    2016-03-18

    A side-gated, ultrathin-channel nanopore FET (SGNAFET) is proposed for fast and label-free DNA sequencing. The concept of the SGNAFET comprises the detection of changes in the channel current during DNA translocation through a nanopore and identifying the four types of nucleotides as a result of these changes. To achieve this goal, both p- and n-type SGNAFETs with a channel thicknesses of 2 or 4 nm were fabricated, and the stable transistor operation of both SGNAFETs in air, water, and a KCl buffer solution were confirmed. In addition, synchronized current changes were observed between the ionic current through the nanopore and the SGNAFET's drain current during DNA translocation through the nanopore.

  17. Voltage-controlled metal binding on polyelectrolyte-functionalized nanopores.

    Science.gov (United States)

    Actis, Paolo; Vilozny, Boaz; Seger, R Adam; Li, Xiang; Jejelowo, Olufisayo; Rinaudo, Marguerite; Pourmand, Nader

    2011-05-17

    Most of the research in the field of nanopore-based platforms is focused on monitoring ion currents and forces as individual molecules translocate through the nanopore. Molecular gating, however, can occur when target analytes interact with receptors appended to the nanopore surface. Here we show that a solid state nanopore functionalized with polyelectrolytes can reversibly bind metal ions, resulting in a reversible, real-time signal that is concentration dependent. Functionalization of the sensor is based on electrostatic interactions, requires no covalent bond formation, and can be monitored in real time. Furthermore, we demonstrate how the applied voltage can be employed to tune the binding properties of the sensor. The sensor has wide-ranging applications and, its simplest incarnation can be used to study binding thermodynamics using purely electrical measurements with no need for labeling.

  18. Forensic SNP Genotyping using Nanopore MinION Sequencing

    Science.gov (United States)

    Cornelis, Senne; Gansemans, Yannick; Deleye, Lieselot; Deforce, Dieter; Van Nieuwerburgh, Filip

    2017-01-01

    One of the latest developments in next generation sequencing is the Oxford Nanopore Technologies’ (ONT) MinION nanopore sequencer. We studied the applicability of this system to perform forensic genotyping of the forensic female DNA standard 9947 A using the 52 SNP-plex assay developed by the SNPforID consortium. All but one of the loci were correctly genotyped. Several SNP loci were identified as problematic for correct and robust genotyping using nanopore sequencing. All these loci contained homopolymers in the sequence flanking the forensic SNP and most of them were already reported as problematic in studies using other sequencing technologies. When these problematic loci are avoided, correct forensic genotyping using nanopore sequencing is technically feasible. PMID:28155888

  19. Current steering effect of GaN nanoporous structure

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chia-Feng, E-mail: cflin@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Department of Electrical Engineering, Yale University, New Haven, CT 06520 (United States); Wang, Jing-Hao; Cheng, Po-Fu; Tseng, Wang-Po; Fan, Feng-Hsu; Wu, Kaun-Chun; Lee, Wen-Che [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Han, Jung [Department of Electrical Engineering, Yale University, New Haven, CT 06520 (United States)

    2014-11-03

    Current steering effect of InGaN light emitting diode (LED) structure was demonstrated by forming a high resistivity GaN nanoporous structure. Disk-array patterns with current-injection bridge structures were fabricated on InGaN LED devices through a focused ion beam (FIB) system. GaN nanoporous structure was formed around the FIB-drilled holes through a electrochemical (EC) wet-etching process on a n-type GaN:Si layer under the InGaN active layer. High emission intensity and small peak wavelength blueshift phenomenon of the electroluminescence spectra were observed in the EC-treated region compared with the non-treated region. The branch-like nanoporous structure was formed along the lateral etched direction to steer the injection current in 5 μm-width bridge structures. In the FIB-drilled hole structure, high light emission intensity of the central-disk region was observed by enlarging the bridge width to 10 μm, with a 5 μm EC-treated width, that reduced the current steering effect and increased the light scattering effect on the nanoporous structure. The EC-treated GaN:Si nanoporous structure acted as a high light scattering structure and a current steering structure that has potential on the current confinement for vertical cavity surface emitting laser applications. - Highlights: • High resistivity nanoporous-GaN formed in InGaN LED through electrochemical process. • Branch-like nanoporous in 5 μm-width bridge structure can steer the injection current. • Nanoporous GaN acted as s light scattering and current steering structures in InGaN LED.

  20. DNA-functionalized solid state nanopore for biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Mussi, V; Fanzio, P; Repetto, L; Firpo, G; Valbusa, U [Nanomed Labs, Physics Department, University of Genova, Advanced Biotechnology Center, Largo R. Benzi, 10 Genova, 16132 (Italy); Scaruffi, P; Stigliani, S; Tonini, G P, E-mail: mussi@fisica.unige.it [Translational Pediatric Oncology, National Institute for Cancer Research (IST), Largo R. Benzi, 10 Genova, 16132 (Italy)

    2010-04-09

    The possible use of nanopores for single DNA molecules biosensing has been demonstrated, but much remains to do in order to develop advanced engineered devices with enhanced stability, and controlled geometry and surface properties. Here we present morphological and electrical characterization of solid state silicon nitride nanopores fabricated by focused ion beam direct milling and chemically functionalized by probe oligonucleotides, with the final aim of developing a versatile tool for biosensing and gene expression profiling.

  1. Hydrophilic nanoporous polystyrenes and 1,2-polybutadienes

    DEFF Research Database (Denmark)

    Guo, Fengxiao; Jankova Atanasova, Katja; Vigild, Martin Etchells;

    2008-01-01

    Nanoporous polymers from ordered block copolymers having hydrophilic cavity surfaces were successfully prepared by two methodologies: ' 1. Nanoporous polystyrenes fromPtBA-b-PS diblock or PDMS-b-PtBA-b-PS triblock copolymer precursors by atom transfer radical polymerization (ATRP), or combination...... different pathways for the conversion of the double bonds of 1,2-PB to bromoisobutyrate by using one to three steps chemical modification. Grafting polyacrylate layers of PPEGMA, PHEMA etc. onto themon...

  2. Antibacterial activity of zinc oxide-coated nanoporous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

  3. Streaming current magnetic fields in a charged nanopore

    Science.gov (United States)

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

    2016-11-01

    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.

  4. 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

  5. Impedance nanopore biosensor: influence of pore dimensions on biosensing performance.

    Science.gov (United States)

    Kant, Krishna; Yu, Jingxian; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-03-07

    Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25-65 nm) and lengths (4-18 μm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 μm provide better biosensing performance.

  6. 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.

  7. DNA Origami-Graphene Hybrid Nanopore for DNA Detection.

    Science.gov (United States)

    Barati Farimani, Amir; Dibaeinia, Payam; Aluru, Narayana R

    2017-01-11

    DNA origami nanostructures can be used to functionalize solid-state nanopores for single molecule studies. In this study, we characterized a nanopore in a DNA origami-graphene heterostructure for DNA detection. The DNA origami nanopore is functionalized with a specific nucleotide type at the edge of the pore. Using extensive molecular dynamics (MD) simulations, we computed and analyzed the ionic conductivity of nanopores in heterostructures carpeted with one or two layers of DNA origami on graphene. We demonstrate that a nanopore in DNA origami-graphene gives rise to distinguishable dwell times for the four DNA base types, whereas for a nanopore in bare graphene, the dwell time is almost the same for all types of bases. The specific interactions (hydrogen bonds) between DNA origami and the translocating DNA strand yield different residence times and ionic currents. We also conclude that the speed of DNA translocation decreases due to the friction between the dangling bases at the pore mouth and the sequencing DNA strands.

  8. Streaming current magnetic fields in a charged nanopore.

    Science.gov (United States)

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

    2016-11-11

    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.

  9. Local solid-state modification of nanopore surface charges

    CERN Document Server

    Kox, Ronald; Chen, Chang; Arjmandi, Nima; Lagae, Liesbet; Borghs, Gustaaf; 10.1088/0957-4484/21/33/335703

    2012-01-01

    The last decade, nanopores have emerged as a new and interesting tool for the study of biological macromolecules like proteins and DNA. While biological pores, especially alpha-hemolysin, have been promising for the detection of DNA, their poor chemical stability limits their use. For this reason, researchers are trying to mimic their behaviour using more stable, solid-state nanopores. The most successful tools to fabricate such nanopores use high energy electron or ions beams to drill or reshape holes in very thin membranes. While the resolution of these methods can be very good, they require tools that are not commonly available and tend to damage and charge the nanopore surface. In this work, we show nanopores that have been fabricated using standard micromachning techniques together with EBID, and present a simple model that is used to estimate the surface charge. The results show that EBID with a silicon oxide precursor can be used to tune the nanopore surface and that the surface charge is stable over a...

  10. Enhanced Field Emission from Well-Patterned Silicon Nanoporous Pillar Arrays

    Institute of Scientific and Technical Information of China (English)

    FU Xiao-Nan; LI Xin-Jian

    2006-01-01

    @@ The silicon nanoporous pillar array (Si-NPA) is synthesized by using hydrothermal etching method, and the electron field emission properties are studied. The results show that Si-NPA has a low turn-on field of 1.48 V/μm at the emission current of 0.1 μA and its field emission is relatively stable. The field emission enhancement of Si-NPA is believed to originate from its unique morphology and structure. Our finding demonstrates that the Si-NPA is a promising candidate material for field emission applications.

  11. Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

    Directory of Open Access Journals (Sweden)

    Katalin Sinkó

    2010-01-01

    Full Text Available Silica or various silicate aerogels can be characterized by highly porous, open cell, low density structures. The synthesis parameters influence the three-dimensional porous structures by modifying the kinetics and mechanism of hydrolysis and condensation processes. Numerous investigations have shown that the structure of porous materials can be tailored by variations in synthesis conditions (e.g., the type of precursors, catalyst, and surfactants; the ratio of water/precursor; the concentrations; the medium pH; and the solvent. The objectives of this review are to summarize and elucidate the effects of chemical conditions on the nanoporous structure of sol-gel derived silicate aerogels.

  12. Multicomponent Transport through Realistic Zeolite Membranes: Characterization & Transport in Nanoporous Networks

    Energy Technology Data Exchange (ETDEWEB)

    William C. Conner

    2007-08-02

    These research studies focused on the characterization and transport for porous solids which comprise both microporosity and mesoporosity. Such materials represent membranes made from zeolites as well as for many new nanoporous solids. Several analytical sorption techniques were developed and evaluated by which these multi-dimensional porous solids could be quantitatively characterized. Notably an approach by which intact membranes could be studied was developed and applied to plate-like and tubular supported zeolitic membranes. Transport processes were studied experimentally and theoretically based on the characterization studies.

  13. Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Peter [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Gillespie, Andrew [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Stalla, David [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Dohnke, Elmar [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics

    2017-02-20

    The purpose of the project “Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage” is the development of materials that store hydrogen (H2) by adsorption in quantities and at conditions that outperform current compressed-gas H2 storage systems for electric power generation from hydrogen fuel cells (HFCs). Prominent areas of interest for HFCs are light-duty vehicles (“hydrogen cars”) and replacement of batteries with HFC systems in a wide spectrum of applications, ranging from forklifts to unmanned areal vehicles to portable power sources. State-of-the-art compressed H2 tanks operate at pressures between 350 and 700 bar at ambient temperature and store 3-4 percent of H2 by weight (wt%) and less than 25 grams of H2 per liter (g/L) of tank volume. Thus, the purpose of the project is to engineer adsorbents that achieve storage capacities better than compressed H2 at pressures less than 350 bar. Adsorption holds H2 molecules as a high-density film on the surface of a solid at low pressure, by virtue of attractive surface-gas interactions. At a given pressure, the density of the adsorbed film is the higher the stronger the binding of the molecules to the surface is (high binding energies). Thus, critical for high storage capacities are high surface areas, high binding energies, and low void fractions (high void fractions, such as in interstitial space between adsorbent particles, “waste” storage volume by holding hydrogen as non-adsorbed gas). Coexistence of high surface area and low void fraction makes the ideal adsorbent a nanoporous monolith, with pores wide enough to hold high-density hydrogen films, narrow enough to minimize storage as non-adsorbed gas, and thin walls between pores to minimize the volume occupied by solid instead of hydrogen. A monolith can be machined to fit into a rectangular tank (low pressure, conformable tank), cylindrical tank

  14. Analysis of electrolyte transport through charged nanopores

    CERN Document Server

    Peters, P B; Bazant, M Z; Biesheuvel, P M

    2015-01-01

    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 fluxes (electrical current, salt flux, fluid velocity) to their respective driving forces (difference in electric potential, salt concentration, pressure). Calculations in literature mainly consider the limit of non-overlapping electrical double layers (EDLs) in the pores and the absence of salt concentration gradients in the axial direction. In the present work these simplifications are relaxed and we discuss the general case with overlapping EDLs and nonzero axial salt concentration gradients. The 3x3 matrix that relates these quantities exhibits Onsager symmetry and for one of the cross coefficients we report a new significant simplification. We describe how Onsager symmetry is preserved under change of variables...

  15. Electroosmotic flow rectification in conical nanopores

    CERN Document Server

    Laohakunakorn, Nadanai

    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 correlated, which leads to the inverse relationship between the magnitudes of EOF and current. Rectification occurs when the pore is driven into states characterized by different salt concentrations depending on the sign of the voltage. The mechanism responsible for this behaviour is concentration polarization, which requires the pore to exhibit the properties of permselectivity and asymmetry.

  16. Electroosmotic flow rectification in conical nanopores.

    Science.gov (United States)

    Laohakunakorn, Nadanai; Keyser, Ulrich F

    2015-07-10

    Recent experimental work has suggested that electroosmotic flows (EOFs) 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 correlated, which leads to the inverse relationship between the magnitudes of EOF and current. Rectification occurs when the pore is driven into states characterized by different salt concentrations depending on the sign of the voltage. The mechanism responsible for this behaviour is concentration polarization, which requires the pore to exhibit the properties of permselectivity and asymmetry.

  17. Enzyme Reactions in Nanoporous, Picoliter Volume Containers

    Energy Technology Data Exchange (ETDEWEB)

    Siuti, Piro [ORNL; Retterer, Scott T [ORNL; Choi, Chang Kyoung [Michigan Technological University; Doktycz, Mitchel John [ORNL

    2012-01-01

    Advancements in nanoscale fabrication allow creation of small volume reaction containers that can facilitate the screening and characterization of enzymes. A porous, ~19 pL volume vessel has been used in this work to carry out enzyme reactions under varying substrate concentrations. Glucose oxidase and horseradish peroxidase can be contained in these structures and diffusively fed with a solution containing glucose and the fluorogenic substrate Amplex Red through the engineered nanoscale pore structure. Fluorescent microscopy was used to monitor the reaction, which was carried out under microfluidic control. Kinetic characteristics of the enzyme were evaluated and compared with results from conventional scale reactions. These picoliter, nanoporous containers can facilitate quick determination of enzyme kinetics in microfluidic systems without the requirement of surface tethering and can be used for applications in drug discovery, clinical diagnostics and high-throughput screening.

  18. Capillary rise of water in hydrophilic nanopores

    CERN Document Server

    Gruener, Simon; Wallacher, Dirk; Kityk, Andriy V; Huber, Patrick; 10.1103/PhysRevE.79.067301

    2009-01-01

    We report on the capillary rise of water in three-dimensional networks of hydrophilic silica pores with 3.5nm and 5nm mean radii, respectively (porous Vycor monoliths). We find classical square root of time Lucas-Washburn laws for the imbibition dynamics over the entire capillary rise times of up to 16h investigated. Provided we assume two preadsorbed strongly bound layers of water molecules resting at the silica walls, which corresponds to a negative velocity slip length of -0.5nm for water flow in silica nanopores, we can describe the filling process by a retained fluidity and capillarity of water in the pore center. This anticipated partitioning in two dynamic components reflects the structural-thermodynamic partitioning in strongly silica bound water layers and capillary condensed water in the pore center which is documented by sorption isotherm measurements.

  19. Procoagulant behavior and platelet microparticle generation on nanoporous alumina.

    Science.gov (United States)

    Ferraz, Natalia; Hong, Jaan; Karlsson Ott, Marjam

    2010-05-01

    In the present work, we have investigated platelet microparticle (PMP) generation in whole blood after contact with nanoporous alumina. Alumina membranes with pore sizes of 20 and 200 nm in diameter were incubated with whole blood and the number of PMP in the fluid phase was determined by flow cytometry. The role of the complement system in PMP generation was investigated using an analog of the potent complement inhibitor compstatin. Moreover, the procoagulant activity of the two pore size membranes were compared by measuring thrombin formation. Results indicated that PMP were not present in the fluid phase after whole blood contact with either of the alumina membranes. However, scanning electron microscope micrographs clearly showed the presence of PMP clusters on the 200 nm pore size alumina, while PMP were practically absent on the 20 nm membrane. We probed no influence of complement activation in PMP generation and adhesion and we hypothesize that other specific material-related protein-platelet interactions are taking place. A clear difference in procoagulant activity between the membranes could also be seen, 20 nm alumina showed 100% higher procoagulant activity than 200 nm membrane. By combining surface evaluation and flow cytometry analyses of the fluid phase, we are able to conclude that 200 nm pore size alumina promotes PMP generation and adhesion while the 20 nm membrane does not appreciably cause any release or adhesion of PMP, thus indicating a direct connection between PMP generation and nanoporosity.

  20. Continuous protein production in nanoporous, picolitre volume containers.

    Science.gov (United States)

    Siuti, Piro; Retterer, Scott T; Doktycz, Mitchel J

    2011-10-21

    The synthetic manufacture of functional proteins enables a bottom-up understanding of the workings of biological systems and opens new opportunities for the treatment of disease. Cell-free protein synthesis is a practical approach for enabling such manufacturing, however, it is typically carried out in fairly large volumes, when compared to a natural cell, leading to increases in cost and loss of efficiency. Here we demonstrate continuous cell free protein synthesis in arrays of cellular scale containers that continuously exchange energy and materials with their environment. A multiscale fabrication process allows the monolithic integration of nanoporous silicon containers within an addressable microfluidic network. Synthesis of enhanced green fluorescent protein (eGFP) in the containers continues beyond 24 h and yields more than twice the amount of protein, on a per volume basis, than conventional scale batch reactions. By mimicking the physical volume and controlled flux of a natural cell, the resulting "cell mimic" devices can enable fundamental studies of biological systems as well as serve applications related to the functional screening of proteins and the on-demand production of biologics.

  1. Characterization of Electrodeposited Nanoporous Ni and NiCu Films

    Science.gov (United States)

    Koboski, Kyla; Hampton, Jennifer

    2013-03-01

    Nanoporous thin films are interesting candidates to catalyze certain reactions because of their large surface areas. This project focuses on the deposition of Ni and NiCu thin films on a Au substrate and further explores the catalysis of the hydrogen evolution reaction (HER). Depositions are created using controlled potential electrolysis. Samples are then dealloyed using linear sweep voltammetry. Before and after the dealloying, all the samples are characterized using multiple techniques. Electrochemical capacitance measurements allow comparisons of sample roughness. HER measurements characterize the reactivity of the sample with respect to the specific catalytic reaction. The Tafel equation is fit to the data to obtain information about the kinetics of the HER of the samples. Other methods for characterizing the samples include scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The use of SEM allows images to be taken of the deposition to determine the change in the structure pre- and post- dealloy of the sample. EDS allows the elemental composition of the deposition to be determined before and after the dealloy stage. This material is based upon work supported by the National Science Foundation under RUI Grant DMR-1104725, MRI Grant CHE-1126462, MRI Grant CHE-0959282, and ARI grant PHY-0963317.

  2. Shale nanopore reconstruction with compressive sensing

    Science.gov (United States)

    Guo, Long; Xiao, Lizhi

    2017-03-01

    With increasing global demand for energy resources, shale gas has been paid considerable attention in recent years. Nanopore geometry is the basis for all microscopic rock physics and petrophysical numerical experiments for shale. At present, nano digital cores can be acquired via thin section reconstruction, nanometer-scale x-ray computed tomography (nano-CT), and focused ion beam and scanning electron microscopy (FIB-SEM). FIB-SEM detects nanoscale pores in the xy-plane with a resolution of up to 0.8 nm voxel‑1, and it is usually provides higher resolution than nano-CT. The main workload associated with FIB-SEM is the need to recut the sample many times and scan every section, with these then being overlaid to create a three-dimensional (3D) pore model. Each cutting distance can be ascertained, but this cannot be controlled precisely because of the fundamental limits of focused ion beams. Many interpolation methods can be used to fit the anisotropy resolution. However, these methods can also alter the geometry of the pores. Nanopores that are close to the limiting resolution are particularly susceptible to stretching. Linear interpolation is likely to lengthen the pores in the low-resolution direction. The subsequent calculation of sensitive physical attributes will be affected by geometric alterations. Through foundational work in the compressive sensing (CS) method, we present a reconstruction workflow for maintaining the pore shape using prior knowledge and reliable information. The images are reassembled with equal distance, so the nanoscale structures can have a resolution of unity in three dimensions.

  3. Ion current rectification, limiting and overlimiting conductances in nanopores.

    Directory of Open Access Journals (Sweden)

    Liesbeth van Oeffelen

    Full Text Available Previous reports on Poisson-Nernst-Planck (PNP simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dependent and steady state PNP simulations under less restrictive boundary conditions, including Neumann boundary conditions applied throughout the membrane relatively far away from the nanopore. We simulated ion currents through cylindrical and conical nanopores with several surface charge configurations, studying the spatial and temporal dependence of the currents contributed by each ion species. This revealed that, due to slow co-diffusion of oppositely charged ions, steady state is generally not reached in simulations or in practice. Furthermore, it is shown that ion concentration polarization is responsible for the observed limiting conductances and ion current rectification in nanopores with asymmetric surface charges or shapes. Hence, after more than a decade of collective research attempting to understand the nature of ion current rectification in solid-state nanopores, a relatively intuitive model is retrieved. Moreover, we measured and simulated current-voltage characteristics of rectifying silicon nitride nanopores presenting overlimiting conductances. The similarity between measurement and simulation shows that overlimiting conductances can result from the increased conductance of the electric double-layer at the membrane surface at the depletion side due to voltage-induced polarization charges. The MATLAB source code of the simulation software is available via the website http://micr.vub.ac.be.

  4. Ion current rectification, limiting and overlimiting conductances in nanopores.

    Science.gov (United States)

    van Oeffelen, Liesbeth; Van Roy, Willem; Idrissi, Hosni; Charlier, Daniel; Lagae, Liesbet; Borghs, Gustaaf

    2015-01-01

    Previous reports on Poisson-Nernst-Planck (PNP) simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dependent and steady state PNP simulations under less restrictive boundary conditions, including Neumann boundary conditions applied throughout the membrane relatively far away from the nanopore. We simulated ion currents through cylindrical and conical nanopores with several surface charge configurations, studying the spatial and temporal dependence of the currents contributed by each ion species. This revealed that, due to slow co-diffusion of oppositely charged ions, steady state is generally not reached in simulations or in practice. Furthermore, it is shown that ion concentration polarization is responsible for the observed limiting conductances and ion current rectification in nanopores with asymmetric surface charges or shapes. Hence, after more than a decade of collective research attempting to understand the nature of ion current rectification in solid-state nanopores, a relatively intuitive model is retrieved. Moreover, we measured and simulated current-voltage characteristics of rectifying silicon nitride nanopores presenting overlimiting conductances. The similarity between measurement and simulation shows that overlimiting conductances can result from the increased conductance of the electric double-layer at the membrane surface at the depletion side due to voltage-induced polarization charges. The MATLAB source code of the simulation software is available via the website http://micr.vub.ac.be.

  5. Regulating Current Rectification and Nanoparticle Transport Through a Salt Gradient in Bipolar Nanopores.

    Science.gov (United States)

    Lin, Chih-Yuan; Yeh, Li-Hsien; Hsu, Jyh-Ping; Tseng, Shiojenn

    2015-09-16

    Tuning of ion and nanoparticle transport is validated through applying a salt gradient in two types of nanopores: the inner wall of a nanopore has bipolar charges and its outer wall neutral (type I), and both the inner and outer walls of a nanopore have bipolar charges (type II). The ion current rectification (ICR) behavior of these nanopores can be regulated by an applied salt gradient: if it is small, the degree of ICR in type II nanopore is more significant than that in type I nanopore; a reversed trend is observed at a sufficiently large salt gradient. If the applied salt gradient and electric field have the same direction, type I nanopore exhibits two significant features that are not observed in type II nanopore: (i) a cation-rich concentration polarization field and an enhanced funneling electric field are present near the cathode side of the nanopore, and (ii) the magnitude of the axial electric field inside the nanopore is reduced. These features imply that applying a salt gradient to type I nanopore is capable of simultaneously enhancing the nanoparticle capture into the nanopore and reducing its translocation velocity inside, so that high sensing performance and resolution can be achieved.

  6. Interplay between inhibited transport and reaction in nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Ackerman, David Michael [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    This work presents a detailed formulation of reaction and diffusion dynamics of molecules in confined pores such as mesoporous silica and zeolites. A general reaction-diffusion model and discrete Monte Carlo simulations are presented. Both transient and steady state behavior is covered. Failure of previous mean-field models for these systems is explained and discussed. A coarse-grained, generalized hydrodynamic model is developed that accurately captures the interplay between reaction and restricted transport in these systems. This method incorporates the non-uniform chemical diffusion behavior present in finite pores with multi-component diffusion. Two methods of calculating these diffusion values are developed: a random walk based approach and a driven diffusion model based on an extension of Fick's law. The effects of reaction, diffusion, pore length, and catalytic site distribution are investigated. In addition to strictly single file motion, quasi-single file diffusion is incorporated into the model to match a range of experimental systems. The connection between these experimental systems and model parameters is made through Langevin dynamics modeling of particles in confined pores.

  7. Modelling the ion-exchange equilibrium in nanoporous materials

    Directory of Open Access Journals (Sweden)

    M. Lukšič

    2012-06-01

    Full Text Available Distribution of a two component electrolyte mixture between the model adsorbent and a bulk aqueous electrolyte solution was studied using the replica Ornstein-Zernike theory and the grand canonical Monte Carlo method. The electrolyte components were modelled to mimic the HCl/NaCl and HCl/CaCl2 mixtures, respectively. The matrix, invaded by the primitive model electrolyte mixture, was formed from monovalent negatively charged spherical obstacles. The solution was treated as a continuous dielectric with the properties of pure water. Comparison of the pair distribution functions (obtained by the two methods between the various ionic species indicated a good agreement between the replica Ornstein-Zernike results and machine calculations. Among thermodynamic properties, the mean activity coefficient of the invaded electrolyte components was calculated. Simple model for the ion-exchange resin was proposed. The selectivity calculations yielded qualitative agreement with the following experimental observations: (i selectivity increases with the increasing capacity of the adsorbent (matrix concentration, (ii the adsorbent is more selective for the ion having higher charge density if its fraction in mixture is smaller.

  8. Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte

    Science.gov (United States)

    Porta-i-Batalla, Maria; Eckstein, Chris; Xifré-Pérez, Elisabet; Formentín, Pilar; Ferré-Borrull, J.; Marsal, Lluis F.

    2016-08-01

    Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells. In this work, we have created and analyzed a stimuli-responsive drug delivery system based on layer-by-layer pH-responsive polyelectrolyte and nanoporous anodic alumina. The results demonstrate that it is possible to control the drug release using a polyelectrolyte multilayer coating that will act as a gate.

  9. Nanoporous SiO2/TiO2 coating with enhanced interfacial compatibility for orthopedic applications

    Science.gov (United States)

    Zhao, Xiaobing; Cao, Hengchun; You, Jing; Cheng, Xingbao; Xie, Youtao; Cao, Huiliang; Liu, Xuanyong

    2015-11-01

    Topographic modification in nanoscale is one of the most often used strategies to enhance the interfacial biocompatibility of implant materials. The aim of this work is to produce SiO2/TiO2 coatings with nanoporous structures and favorable biological properties by atmospheric plasma spraying technology and subsequently hydrothermal etching method in hydrogen fluoride solution. The effects of hydrothermal time and temperature on the microstructures and osteoblast behavior of the SiO2/TiO2 coatings were investigated. Results demonstrated that the as-sprayed SiO2/TiO2 coating was mainly composed of rutile and quartz phases. After etching, nanoporous topographies were formed on the surface of the coatings and the hydrothermal parameters had important influences on the size and shape of the pores. The interconnected network pores on the coating surface could only produce at the appropriate hydrothermal conditions (the hydrothermal time and temperature were 60 min and 100 °C, respectively). Compared to TiO2 and SiO2/TiO2 coatings, nanoporous SiO2/TiO2 coatings could enhance osteoblast adhesion and promote cell proliferation. The results suggested the potential application of the porous coatings for enhancing the biological performance of the currently used dental and orthopedic implant materials.

  10. Thermal Investigations of Periodically Nanoporous Si Films -- The Impact of Structure Sizes and Pore-Edge Amorphization

    Science.gov (United States)

    Xu, Dongchao; Zhao, Hongbo; Hao, Qing

    In recent years, nanoporous Si films have been intensively studied as promising thermoelectric materials, which mainly benefits from their dramatically reduced lattice thermal conductivity kL and bulk-like electrical properties.1,2 Despite many encouraging results, challenges still exist in the theoretical explanation of the observed low kL.3 Existing studies mainly attribute the low kL to 1) phonon bandstructure modification by coherent phonon processes in a periodic structure (phononic effects), and/or 2) pore-edge defects. In this work, temperature-dependent kL is measured for nanoporous Si films with different pore sizes and spacing to compare with model predictions. For systematic studies, two fabrication techniques are used to drill the nanopores: 1) reactive ion etching, and 2) a focus ion beam to introduce more pore-edge defects. The results from this work will provide guidance for phonon engineering in general materials with periodic interfaces or boundaries. References: 1. Tang et al., Nano Letters 10, 4279-4283 (2010). 2. Yu et al., Nature Nanotechnology 5, 718-721 (2010). 3. Cahill et al., Applied Physics Reviews 1, 011305/1-45 (2014) Nanoscale thermal transport. II. 2003-2012.

  11. Fabrication and Modification of Nanoporous Silicon Particles

    Science.gov (United States)

    Ferrari, Mauro; Liu, Xuewu

    2010-01-01

    Silicon-based nanoporous particles as biodegradable drug carriers are advantageous in permeation, controlled release, and targeting. The use of biodegradable nanoporous silicon and silicon dioxide, with proper surface treatments, allows sustained drug release within the target site over a period of days, or even weeks, due to selective surface coating. A variety of surface treatment protocols are available for silicon-based particles to be stabilized, functionalized, or modified as required. Coated polyethylene glycol (PEG) chains showed the effective depression of both plasma protein adsorption and cell attachment to the modified surfaces, as well as the advantage of long circulating. Porous silicon particles are micromachined by lithography. Compared to the synthesis route of the nanomaterials, the advantages include: (1) the capability to make different shapes, not only spherical particles but also square, rectangular, or ellipse cross sections, etc.; (2) the capability for very precise dimension control; (3) the capacity for porosity and pore profile control; and (4) allowance of complex surface modification. The particle patterns as small as 60 nm can be fabricated using the state-of-the-art photolithography. The pores in silicon can be fabricated by exposing the silicon in an HF/ethanol solution and then subjecting the pores to an electrical current. The size and shape of the pores inside silicon can be adjusted by the doping of the silicon, electrical current application, the composition of the electrolyte solution, and etching time. The surface of the silicon particles can be modified by many means to provide targeted delivery and on-site permanence for extended release. Multiple active agents can be co-loaded into the particles. Because the surface modification of particles can be done on wafers before the mechanical release, asymmetrical surface modification is feasible. Starting from silicon wafers, a treatment, such as KOH dipping or reactive ion

  12. Single molecule transistor based nanopore for the detection of nicotine

    Energy Technology Data Exchange (ETDEWEB)

    Ray, S. J., E-mail: ray.sjr@gmail.com [Institute of Materials Science, Technical University of Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany)

    2014-12-28

    A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realised from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.

  13. Nanoporous Pirani sensor based on anodic aluminum oxide

    Science.gov (United States)

    Jeon, Gwang-Jae; Kim, Woo Young; Shim, Hyun Bin; Lee, Hee Chul

    2016-09-01

    A nanoporous Pirani sensor based on anodic aluminum oxide (AAO) is proposed, and the quantitative relationship between the performance of the sensor and the porosity of the AAO membrane is characterized with a theoretical model. The proposed Pirani sensor is composed of a metallic resistor on a suspended nanoporous membrane, which simultaneously serves as the sensing area and the supporting structure. The AAO membrane has numerous vertically-tufted nanopores, resulting in a lower measurable pressure limit due to both the increased effective sensing area and the decreased effective thermal loss through the supporting structure. Additionally, the suspended AAO membrane structure, with its outer periphery anchored to the substrate, known as a closed-type design, is demonstrated using nanopores of AAO as an etch hole without a bulk micromachining process used on the substrate. In a CMOS-compatible process, a 200 μm × 200 μm nanoporous Pirani sensor with porosity of 25% was capable of measuring the pressure from 0.1 mTorr to 760 Torr. With adjustment of the porosity of the AAO, the measurable range could be extended toward lower pressures of more than one decade compared to a non-porous membrane with an identical footprint.

  14. Structure and adsorption of water in nonuniform cylindrical nanopores

    Science.gov (United States)

    Torrie, G. M.; Lakatos, G.; Patey, G. N.

    2010-12-01

    Grand canonical Monte Carlo simulations are used to examine the adsorption and structure of water in the interior of cylindrical nanopores in which the axial symmetry is broken either by varying the radius as a function of position along the pore axis or by introducing regions where the characteristic strength of the water-nanopore interaction is reduced. Using the extended simple point charge (SPC/E) model for water, nanopores with a uniform radius of 6.0 Å are found to fill with water at chemical potentials approximately 0.5 kJ/mol higher than the chemical potential of the saturated vapor. The water in these filled pores exists in either a weakly structured fluidlike state or a highly structured uniformly polarized state composed of a series of stacked water clusters with pentagonal cross sections. This highly structured state can be disrupted by creating hydrophobic regions on the surface of the nanopore, and the degree of disruption can be systematically controlled by adjusting the size of the hydrophobic regions. In particular, hydrophobic banded regions with lengths larger than 9.2 Å result in a complete loss of structure and the formation of a liquid-vapor coexistence in the tube interior. Similarly, the introduction of spatial variation in the nanopore radius can produce two condensation transitions at distinct points along the filling isotherm.

  15. Atomistic simulation of Voronoi-based coated nanoporous metals

    Science.gov (United States)

    Onur Yildiz, Yunus; Kirca, Mesut

    2017-02-01

    In this study, a new method developed for the generation of periodic atomistic models of coated and uncoated nanoporous metals (NPMs) is presented by examining the thermodynamic stability of coated nanoporous structures. The proposed method is mainly based on the Voronoi tessellation technique, which provides the ability to control cross-sectional dimension and slenderness of ligaments as well as the thickness of coating. By the utilization of the method, molecular dynamic (MD) simulations of randomly structured NPMs with coating can be performed efficiently in order to investigate their physical characteristics. In this context, for the purpose of demonstrating the functionality of the method, sample atomistic models of Au/Pt NPMs are generated and the effects of coating and porosity on the thermodynamic stability are investigated by using MD simulations. In addition to that, uniaxial tensile loading simulations are performed via MD technique to validate the nanoporous models by comparing the effective Young’s modulus values with the results from literature. Based on the results, while it is demonstrated that coating the nanoporous structures slightly decreases the structural stability causing atomistic configurational changes, it is also shown that the stability of the atomistic models is higher at lower porosities. Furthermore, adaptive common neighbour analysis is also performed to identify the stabilized atomistic structure after the coating process, which provides direct foresights for the mechanical behaviour of coated nanoporous structures.

  16. Antibacterial hemostatic dressings with nanoporous bioglass containing silver

    Directory of Open Access Journals (Sweden)

    Hu G

    2012-05-01

    Full Text Available Gangfeng Hu,1 Luwei Xiao,2 Peijian Tong,2 Dawei Bi,1 Hui Wang,1 Haitao Ma,1 Gang Zhu,1 Hui Liu21The First People’s Hospital of Xiaoshan, Hangzhou, China; 2Zhejiang Traditional Chinese Medical University, Hangzhou, ChinaAbstract: Nanoporous bioglass containing silver (n-BGS was fabricated using the sol-gel method, with cetyltrimethyl ammonium bromide as template. The results showed that n-BGS with nanoporous structure had a surface area of 467 m2/g and a pore size of around 6 nm, and exhibited a significantly higher water absorption rate compared with BGS without nanopores. The n-BGS containing small amounts of silver (Ag had a slight effect on its surface area. The n-BGS containing 0.02 wt% Ag, without cytotoxicity, had a good antibacterial effect on Escherichia coli, and its antibacterial rate reached 99% in 12 hours. The n-BGS’s clotting ability significantly decreased prothrombin time (PT and activated partial thromboplastin time (APTT, indicating n-BGS with a higher surface area could significantly promote blood clotting (by decreasing clotting time compared with BGS without nanopores. Effective hemostasis was achieved in skin injury models, and bleeding time was reduced. It is suggested that n-BGS could be a good dressing, with antibacterial and hemostatic properties, which might shorten wound bleeding time and control hemorrhage.Keywords: antibacterial, bioglass, cytotoxicity, dressing, hemostasis, nanopore, silver

  17. High resolution transmission electron microscopic study of nanoporous carbon consisting of curved single graphite sheets

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, L.N.; Bursill, L.A.

    1997-12-31

    A high resolution transmission electron microscopic study of a nanoporous carbon rich in curved graphite monolayers is presented. Observations of very thin regions. including the effect of tilting the specimen with respect to the electron beam, are reported. The initiation of single sheet material on an oriented graphite substrate is also observed. When combined with image simulations and independent measurements of the density (1.37g cm {sup -3}) and sp{sup 3}/sp{sup 2}+sp{sup 2} bonding fraction (0.16), these observations suggest that this material is a two phase mixture containing a relatively low density aggregation of essentially capped single shells like squat nanotubes and polyhedra, plus a relatively dense `amorphous` carbon structure which may be described using a random-Schwarzite model. Some negatively-curved sheets were also identified in the low density phase. Finally, some discussion is offered regarding the growth mechanisms responsible for this nanoporous carbon and its relationship with the structures of amorphous carbons across a broad range of densities, porosities and sp{sup 3}/sp{sup 2}+sp{sup 3} bonding fractions. 29 refs., 8 figs., 2 tabs.

  18. Effects of ultrathin coating on the tensile behavior of nanoporous gold

    Science.gov (United States)

    Yildiz, Yunus Onur; Kirca, Mesut

    2017-08-01

    In this study, the mechanical properties of nanoporous gold (np-Au) coated with different ultrathin metallic materials (i.e., platinum and silver) are studied through molecular dynamics simulations. A new atomistic modelling technique, which is based on the Voronoi tessellation method providing periodic atomistic specimens, is used for the geometric representation of np-Au structure. Three different coating thickness values are used to examine the role of thickness on the coating performance under tensile loading at a constant strain rate. Several parameters, including Young's modulus, yield, and ultimate strengths, are utilized to compare the mechanical characteristics of coated and uncoated np-Au specimens. Moreover, adaptive common neighbor analyses are performed on the specimens for the purpose of understanding the deformation mechanisms of coated and uncoated nanoporous specimens comprehensively by monitoring the microstructural evolution of the crystal structure of the specimens within the deformation process. As a main finding from the simulations, it is observed that the mechanical properties of np-Au are improved by coating independently of the coating material type. However, enhancements on the yield and ultimate strengths maintained by platinum coating are greater than those provided by the silver coating.

  19. Characterization of hydrogen responsive nanoporous palladium films synthesized via a spontaneous galvanic displacement reaction

    Science.gov (United States)

    Patton, J. F.; Lavrik, N. V.; Joy, D. C.; Hunter, S. R.; Datskos, P. G.; Smith, D. B.; Sepaniak, M. J.

    2012-11-01

    A model is presented regarding the mechanistic properties associated with the interaction of hydrogen with nanoporous palladium (np-Pd) films prepared using a spontaneous galvanic displacement reaction (SGDR), which involves PdCl2 reduction by atomic Ag. Characterization of these films shows both chemical and morphological factors, which influence the performance characteristics of np-Pd microcantilever (MC) nanomechanical sensing devices. Raman spectroscopy, uniquely complemented with MC response profiles, is used to explore the chemical influence of palladium oxide (PdO). These combined techniques support a reaction mechanism that provides for rapid response to H2 and recovery in the presence of O2. Post-SGDR processing via reduction of PdCl2(s) in a H2 environment results in a segregated nanoparticle three-dimensional matrix dispersed in a silver layer. The porous nature of the reduced material is shown by high resolution scanning electron microscopy. Extended grain boundaries, typical of these materials, result in a greater surface area conducive to fast sorption/desorption of hydrogen, encouraged by the presence of PdO. X-ray diffraction and inductively coupled plasma-optical emission spectroscopy are employed to study changes in morphology and chemistry occurring in these nanoporous films under different processing conditions. The unique nature of chemical/morphological effects, as demonstrated by the above characterization methods, provides evidence in support of observed nanomechanical response/recovery profiles offering insight for catalysis, H2 storage and improved sensing applications.

  20. General synthesis of sponge-like ultrafine nanoporous metals by dealloying in citric acid

    Institute of Scientific and Technical Information of China (English)

    Hongjie Xu; Shujie Pang; Yu Jin; Tao Zhang

    2016-01-01

    A general method is proposed to synthesize ultrafine nanoporous Cu,Ag,and Ni with novel sponge-like morphologies,high porosities,and large surface areas.The materials are produced by dealloying Mg65M25Y10 (M =Cu,Ag,and Ni) metallic glasses in citric acid.Citric acid played a key role due to its capping effect,which reduced the surface diffusion of metals.A structural model consistent with the sponge-like morphology was constructed to calculate the porosity and the surface area.The mechanism of the dealloying process in dtric add,involving ligament formation and coarsening,was illustrated.The mechanism was capable of explaining the experimental trends of dealloying,especially the morphology.A glucose sensor,which can be further developed into a high-precision real-time glucose monitor for medical use,was constructed using sponge-like nanoporous copper.Our findings are not only relevant to understanding the dealloying mechanism of metallic glasses,but also provide promising materials for multiple applications.

  1. A FIB-nanotomography method for accurate 3D reconstruction of open nanoporous structures

    Energy Technology Data Exchange (ETDEWEB)

    Mangipudi, K.R., E-mail: mangipudi@ump.gwdg.de [Institut für Materialphysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Radisch, V., E-mail: vradisch@ump.gwdg.de [Institut für Materialphysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Holzer, L., E-mail: holz@zhaw.ch [Züricher Hochschule für Angewandte Wissenschaften, Institute of Computational Physics, Wildbachstrasse 21, CH-8400 Winterthur (Switzerland); Volkert, C.A., E-mail: volkert@ump.gwdg.de [Institut für Materialphysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

    2016-04-15

    We present an automated focused ion beam nanotomography method for nanoporous microstructures with open porosity, and apply it to reconstruct nanoporous gold (np-Au) structures with ligament sizes on the order of a few tens of nanometers. This method uses serial sectioning of a well-defined wedge-shaped geometry to determine the thickness of individual slices from the changes in the sample width in successive cross-sectional images. The pore space of a selected region of the np-Au is infiltrated with ion-beam-deposited Pt composite before serial sectioning. The cross-sectional images are binarized and stacked according to the individual slice thicknesses, and then processed using standard reconstruction methods. For the image conditions and sample geometry used here, we are able to determine the thickness of individual slices with an accuracy much smaller than a pixel. The accuracy of the new method based on actual slice thickness is assessed by comparing it with (i) a reconstruction using the same cross-sectional images but assuming a constant slice thickness, and (ii) a reconstruction using traditional FIB-tomography method employing constant slice thickness. The morphology and topology of the structures are characterized using ligament and pore size distributions, interface shape distribution functions, interface normal distributions, and genus. The results suggest that the morphology and topology of the final reconstructions are significantly influenced when a constant slice thickness is assumed. The study reveals grain-to-grain variations in the morphology and topology of np-Au. - Highlights: • FIB nanotomography of nanoporous structure with features sizes of ∼40 nm or less. • Accurate determination of individual slice thickness with subpixel precision. • The method preserves surface topography. • Quantitative 3D microstructural analysis of materials with open porosity.

  2. Formation of nanoporous pyrobitumen residues during maturation processes within the Barnett Shale (Fort Worth Basin)

    Science.gov (United States)

    Bernard, S.; Wirth, R.; Schreiber, A.; Schulz, H.-M.; Horsfield, B.

    2012-04-01

    Hydrocarbon generation processes occur within organic-rich shales as a response to increases in thermal maturation. Shale gas reservoir quality is thought to be largely dependent on the extent to which solid organic material has been converted to pore space during catagenesis. Although pores may drastically vary in variety and abundance within differing shales, the occurrence of nanopores within organic particles has recently been documented for an important number of gas shale systems (i.e., Barnett, Haynesville, Utica, Eagle Ford, Woodford, Horn River, Marcellus, Posidonia …). However, despite their ubiquitous nature, the formation and the geochemical nature of these nanoporous organic compounds remain unclear. Here, we present the characterization of samples from the organic-rich Mississippian Barnett shale gas system (Fort Worth Basin, Texas, USA) at varying stages of thermal maturation. Using a combination of compositional organic geochemistry and spectromicroscopy techniques, including synchrotron-based scanning transmission X-ray microscopy (STXM - data collected using the CLS 10ID-1 STXM beamline) and transmission electron microscopy (TEM), we document a net increase in sample geochemical heterogeneity with increasing maturity. In addition to the presence of bitumen in samples of oil window maturity, very likely genetically derived from thermally degraded kerogen, the formation of nanoporous pyrobitumen has been inferred for samples of gas window maturity, likely resulting from the formation of gaseous hydrocarbons by secondary cracking of bitumen compounds. By providing in-situ insights into the fate of bitumen and pyrobitumen as a response to the thermal evolution of the macromolecular structure of kerogen, the present contribution constitutes an important step towards better constraining hydrocarbon generation processes occurring within unconventional gas shale systems.

  3. Nanoporous Silver Film Fabricated by Oxygen Plasma: A Facile Approach for SERS Substrates.

    Science.gov (United States)

    Ma, Chaoxiong; Trujillo, Michael J; Camden, Jon P

    2016-09-14

    Nanoporous metal films are promising substrates for surfaced-enhanced Raman scattering (SERS) measurement, owing to their homogeneity, large surface area, and abundant hot-spots. Herein, a facile procedure was developed to fabricate nanoporous Ag film on various substrate surfaces. Thermally deposited Ag film was first treated with O2 plasma, resulting in porous Ag/AgxO film (AgxO-NF) with nanoscale feature. Sodium citrate was then used to reduce AgxO to Ag, forming nanoporous Ag film (AgNF) with similar morphology. The AgNF substrate demonstrates 30-fold higher Raman intensity than Ag film over polystyrene nanospheres (d = 600 nm) using 4-mercaptobenzoic acid (4-MBA) as the sensing molecule. Comparing with ordinary Raman measurement on 4-MBA solution, an enhancement factor of ∼6 × 10(6) was determined for AgNF. The AgNF substrate was evaluated for benzoic acid, 4-nitrophenol, and 2-mercaptoethanesulfonate, showing high SERS sensitivity for chemicals that bind weakly to Ag surface and molecules with relatively small Raman cross section at micromolar concentration. In addition to its simplicity, the procedure can be applied to various materials such as transparency film, filter paper, hard polystyrene film, and aluminum foil, revealing similar Raman sensitivity. By testing the durability of the substrate, we found that the AgxO films can be stored in ambient conditions for more than 90 days and still deliver the same SERS intensity if the films are treated with sodium citrate before use. These results demonstrate the advantage of the proposed approach for mass production of low-cost, sensitive, and durable SERS substrates. The transferable nature of these AgNF to different flexible surfaces also allows their easy integration with other sensing schemes.

  4. MspA nanopores from subunit dimers.

    Directory of Open Access Journals (Sweden)

    Mikhail Pavlenok

    Full Text Available Mycobacterium smegmatis porin A (MspA forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated that the peptide linkers did not prohibit correct folding and localization of MspA. However, expression levels were reduced by 10-fold compared to wild-type MspA. MspA is ideal for nanopore sequencing due to its unique pore geometry and its robustness. To assess the usefulness of MspA made from dimeric subunits for DNA sequencing, we linked two M1-MspA monomers, whose constriction zones were modified to enable DNA translocation. Lipid bilayer experiments demonstrated that this construct also formed functional channels. Voltage gating of MspA pores made from M1 monomers and M1-M1 dimers was identical indicating similar structural and dynamic channel properties. Glucose uptake in M. smegmatis cells lacking porins was restored by expressing the dimeric mspA M1 gene indicating correct folding and localization of M1-M1 pores in their native membrane. Single-stranded DNA hairpins produced identical ionic current blockades in pores made from monomers and subunit dimers demonstrating that M1-M1 pores are suitable for DNA sequencing. This study provides the proof of principle that production of single-chain MspA pores in M. smegmatis is feasible and paves the way for generating MspA pores with altered stoichiometries. Subunit dimers enable better control of the chemical and physical properties of the constriction zone of MspA. This approach will be valuable both in understanding transport across the outer membrane in mycobacteria and in tailoring MspA for nanopore

  5. Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes

    Science.gov (United States)

    Wang, Luda; Boutilier, Michael S. H.; Kidambi, Piran R.; Jang, Doojoon; Hadjiconstantinou, Nicolas G.; Karnik, Rohit

    2017-06-01

    Graphene and other two-dimensional materials offer a new approach to controlling mass transport at the nanoscale. These materials can sustain nanoscale pores in their rigid lattices and due to their minimum possible material thickness, high mechanical strength and chemical robustness, they could be used to address persistent challenges in membrane separations. Here we discuss theoretical and experimental developments in the emerging field of nanoporous atomically thin membranes, focusing on the fundamental mechanisms of gas- and liquid-phase transport, membrane fabrication techniques and advances towards practical application. We highlight potential functional characteristics of the membranes and discuss applications where they are expected to offer advantages. Finally, we outline the major scientific questions and technological challenges that need to be addressed to bridge the gap from theoretical simulations and proof-of-concept experiments to real-world applications.

  6. Nanoporous metal organic frameworks as hybrid polymer-metal composites for drug delivery and biomedical applications.

    Science.gov (United States)

    Beg, Sarwar; Rahman, Mahfoozur; Jain, Atul; Saini, Sumant; Midoux, Patrick; Pichon, Chantal; Ahmad, Farhan Jalees; Akhter, Sohail

    2017-04-01

    Metal organic frameworks (MOFs), porous hybrid polymer-metal composites at the nanoscale, are recent innovations in the field of chemistry; they are novel polymeric materials with diverse biomedical applications. MOFs are nanoporous materials, consisting of metal ions linked together by organic bridging ligands. The unique physical and chemical characteristics of MOFs have attracted wider attention from the scientific community, exploring their utility in the field of material science, biology, nanotechnology and drug delivery. The practical feasibility of MOFs is possible owing to their abilities for biodegradability, excellent porosity, high loading capacity, ease of surface modification, among others. In this regard, this review provides an account of various types of MOFs, their physiochemical characteristics and use in diverse disciplines of biomedical sciences - with special emphasis on drug delivery and theranostics. Moreover, this review also highlights the stability and toxicity issues of MOFs, along with their market potential for biomedical applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Mapping the ion current distribution in nanopore/electrode devices.

    Science.gov (United States)

    Rutkowska, Agnieszka; Edel, Joshua B; Albrecht, Tim

    2013-01-22

    Solid-state nanopores with integrated electrodes have interesting prospects in next-generation single-molecule biosensing and sequencing. These include "gated" nanopores with a single electrode integrated into the membrane, as well as two-electrode designs, such as a transversal tunneling junction. Here we report the first comprehensive analysis of current flow in a three-electrode device as a model for this class of sensors. As a new feature, we observe apparent rectification in the pore current that is rooted in the current distribution of the cell, rather than the geometry or electrostatics of the pore. We benchmark our results against a recently developed theoretical model and define operational parameters for nanopore/electrode structures. Our findings thus facilitate the rational design of such sensor devices.

  8. Multistep Current Signal in Protein Translocation through Graphene Nanopores

    KAUST Repository

    Bonome, Emma Letizia

    2015-05-07

    © 2015 American Chemical Society. In nanopore sensing experiments, the properties of molecules are probed by the variation of ionic currents flowing through the nanopore. In this context, the electronic properties and the single-layer thickness of graphene constitute a major advantage for molecule characterization. Here we analyze the translocation pathway of the thioredoxin protein across a graphene nanopore, and the related ionic currents, by integrating two nonequilibrium molecular dynamics methods with a bioinformatic structural analysis. To obtain a qualitative picture of the translocation process and to identify salient features we performed unsupervised structural clustering on translocation conformations. This allowed us to identify some specific and robust translocation intermediates, characterized by significantly different ionic current flows. We found that the ion current strictly anticorrelates with the amount of pore occupancy by thioredoxin residues, providing a putative explanation of the multilevel current scenario observed in recently published translocation experiments.

  9. Logic Gate Operation by DNA Translocation through Biological Nanopores.

    Directory of Open Access Journals (Sweden)

    Hiroki Yasuga

    Full Text Available Logical operations using biological molecules, such as DNA computing or programmable diagnosis using DNA, have recently received attention. Challenges remain with respect to the development of such systems, including label-free output detection and the rapidity of operation. Here, we propose integration of biological nanopores with DNA molecules for development of a logical operating system. We configured outputs "1" and "0" as single-stranded DNA (ssDNA that is or is not translocated through a nanopore; unlabeled DNA was detected electrically. A negative-AND (NAND operation was successfully conducted within approximately 10 min, which is rapid compared with previous studies using unlabeled DNA. In addition, this operation was executed in a four-droplet network. DNA molecules and associated information were transferred among droplets via biological nanopores. This system would facilitate linking of molecules and electronic interfaces. Thus, it could be applied to molecular robotics, genetic engineering, and even medical diagnosis and treatment.

  10. Investigation and Characterisation of Resizeable Nanopores in an Elastomeric Membrane

    Science.gov (United States)

    Willmott, Geoff

    2008-03-01

    Experimental and theoretical work relating to the development of resizeable synthetic nanopores will be presented. The nanopores, which are roughly conical, are formed by puncturing a relatively thick (˜250 μm) elastomeric membrane with an STM tip. The aperture can be closed and the size can be dynamically controlled by stretching the elastomer [1]. Use of this technology presents a collection of interesting physical problems, covering topics that include the failure and mechanical properties of the elastomer, flow of ionic current through the aperture and particle sensing using the resistive pulse technique. Synthetic nanopores have potential applications in many fields, but especially relating to nanoscale sensing and diagnostic devices, and replication of ion channels in living cells. [1] S. J. Sowerby, M. F. Broom, G. B. Petersen, Dynamically Resizable Nanometre-Scale Apertures for Molecular Sensing, Sensors and Actuators B: Chemical 123 (1), pp. 325-330 (2007)

  11. Solid-State Nanopore-Based DNA Sequencing Technology

    Directory of Open Access Journals (Sweden)

    Zewen Liu

    2016-01-01

    Full Text Available The solid-state nanopore-based DNA sequencing technology is becoming more and more attractive for its brand new future in gene detection field. The challenges that need to be addressed are diverse: the effective methods to detect base-specific signatures, the control of the nanopore’s size and surface properties, and the modulation of translocation velocity and behavior of the DNA molecules. Among these challenges, the realization of the high-quality nanopores with the help of modern micro/nanofabrication technologies is a crucial one. In this paper, typical technologies applied in the field of solid-state nanopore-based DNA sequencing have been reviewed.

  12. Transport behavior of water molecules through two-dimensional nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chongqin; Li, Hui; Meng, Sheng, E-mail: smeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-11-14

    Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules.

  13. Transport behavior of water molecules through two-dimensional nanopores

    Science.gov (United States)

    Zhu, Chongqin; Li, Hui; Meng, Sheng

    2014-11-01

    Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules.

  14. Enhanced potassium selectivity in a bioinspired solid nanopore.

    Science.gov (United States)

    Picaud, Fabien; Kraszewski, Sebastian; Ramseyer, Christophe; Balme, Sébastien; Déjardin, Philippe; Janot, Jean Marc; Henn, François

    2013-12-01

    Biological ion channels present unique ionic properties. They can be highly permeable to ions, while selecting only one type of ions, without external energy supply. An important research field has been developed to transfer these properties to solid state nanoporous membranes in order to develop artificial biomimetic nanofilters. One of the promising ways to develop biomimetic structures is based on the direct insertion of the gramicidin A, i.e. an ionic channel, inside a nanopore. Experiments have recently proved the feasibility of such a hybrid membrane with very interesting results regarding the ionic selectivity. Here, we propose to interpret these experiments using theoretical molecular dynamic simulations which allow us to analyze more profoundly the structures of the proteins confined inside the nanopore and the relation between their conformation and the observed ionic properties.

  15. Theory of Sorption Hysteresis in Nanoporous Solids: II. Molecular condensation

    CERN Document Server

    Bazant, Martin Z

    2011-01-01

    Motivated by the puzzle of sorption hysteresis in Portland cement concrete or cement paste, we develop in Part II of this study a general theory of vapor sorption and desorption from nanoporous solids, which attributes hysteresis to hindered molecular condensation with attractive lateral interactions. The classical mean-field theory of van der Waals is applied to predict the dependence of hysteresis on temperature and pore size, using the regular solution model and gradient energy of Cahn and Hilliard. A simple "hierarchical wetting" model for thin nanopores is developed to describe the case of strong wetting by the first monolayer, followed by condensation of nanodroplets and nanobubbles in the bulk. The model predicts a larger hysteresis critical temperature and enhanced hysteresis for molecular condensation across nanopores at high vapor pressure than within monolayers at low vapor pressure. For heterogeneous pores, the theory predicts sorption/desorption sequences similar to those seen in molecular dynami...

  16. A tip-attached tuning fork sensor for the control of DNA translocation through a nanopore

    Science.gov (United States)

    Hyun, Changbae; Kaur, Harpreet; Huang, Tao; Li, Jiali

    2017-02-01

    In this work, we demonstrate that a tuning fork can be used as a force detecting sensor for manipulating DNA molecules and for controlling the DNA translocation rate through a nanopore. One prong of a tuning fork is glued with a probe tip which DNA molecules can be attached to. To control the motion and position of the tip, the tuning fork is fixed to a nanopositioning system which has sub-nanometer position control. A fluidic chamber is designed to fulfill many requirements for the experiment: for the access of a DNA-attached tip approaching to a nanopore, for housing a nanopore chip, and for measuring ionic current through a solid-state nanopore with a pair of electrodes. The location of a nanopore is first observed by transmission electron microscopy, and then is determined inside the liquid chambers with an optical microscope combined with local scanning the probe tip on the nanopore surface. When a DNA-immobilized tip approaches a membrane surface near a nanopore, free ends of the immobilized DNA strings can be pulled and trapped into the pore by an applied voltage across the nanopore chip, resulting in an ionic current reduction through the nanopore. The trapped DNA molecules can be lifted up from the nanopore at a user controlled speed. This integrated apparatus allows manipulation of biomolecules (DNA, RNA, and proteins) attached to a probe tip with sub-nanometer precision, and simultaneously allows measurement of the biomolecules by a nanopore device.

  17. Optical observation of DNA translocation through Al2O3 sputtered silicon nanopores in porous membrane

    Science.gov (United States)

    Yamazaki, Hirohito; Ito, Shintaro; Esashika, Keiko; Taguchi, Yoshihiro; Saiki, Toshiharu

    2016-03-01

    Nanopore sensors are being developed as a platform for analyzing single DNA, RNA, and protein. In nanopore sensors, ionic current measurement is widely used and proof-of-concept of nanopore DNA sequencing by it has been demonstrated by previous studies. Recently, we proposed an alternative platform of nanopore DNA sequencing that incorporates ultraviolet light and porous silicon membrane to perform high-throughput measurement. In the development of our DNA sequencing platform, controlling nanopore size in porous silicon membrane is essential but remains a challenge. Here, we report on observation of DNA translocation through Al2O3 sputtered silicon nanopores (Al2O3 nanopores) by our optical scheme. Electromagnetic wave simulation was performed to analyze the excitation volume on Al2O3 nanopores generated by focused ultraviolet light. In the experiment, DNA translocation time through Al2O3 nanopores was compared with that of silicon nanopores and we examined the effect of nanopore density and thickness of membrane by supplementing the static electric field simulation.

  18. Enzyme Reactions in Nanoporous, Picoliter Volume Containers

    Science.gov (United States)

    Siuti, Piro; Retterer, Scott T.; Choi, Chang-Kyoung; Doktycz, Mitchel J.

    2012-01-01

    Advancements in nanoscale fabrication allow creation of small volume reaction containers that can facilitate the screening and characterization of enzymes. A porous, ~19 pL volume vessel has been used in this work to carry out enzyme reactions under varying substrate concentrations. Assessment of small molecule and Green Fluorescent Protein diffusion from the vessels indicates that pore sizes on order of 10 nm can be obtained, allowing capture of proteins and diffusive exchange of small molecules. Glucose oxidase and horseradish peroxidase can be contained in these structures and diffusively fed with a solution containing glucose and the fluorogenic substrate Amplex Red™ through the engineered nanoscale pore structure. Fluorescent microscopy was used to monitor the reaction, which was carried out under microfluidic control. Kinetic characteristics of the enzyme (Km and Vmax) were evaluated and compared with results from conventional scale reactions. These picoliter, nanoporous containers can facilitate quick determination of enzyme kinetics in microfluidic systems without the requirement of surface tethering and can be used for applications in drug discovery, clinical diagnostics and high-throughput screening. PMID:22148720

  19. Electroosmotic access resistance of a nanopore

    Science.gov (United States)

    Ghosal, Sandip; Sherwood, John D.; Mao, Mao

    2014-11-01

    Electroosmotic flow through a nanopore that traverses a dielectric membrane with a fixed surface charge density is considered. In the limit where the surface charge is small and the applied electric field weak, the reciprocal theorem is used to derive an expression for the electroosmotic flux through the pore up to quadratures over the fluid volume. Thus, an ``electroosmotic conductance'' (the fluid flux per unit applied voltage) may be defined in analogy to the corresponding electrical conductance of a hole in an insulating membrane immersed in a uniform conductor. In the limit when the membrane is thick compared to the pore diameter, the usual result for the electroosmotic conductance through long cylindrical channels (which varies inversely as the membrane thickness) is recovered. The electroosmotic conductance is shown to approach a finite value for an infinitely thin membrane: this residual electroosmotic resistance (inverse of conductance) is analogous to the concept of ``access resistance of a pore'' in the corresponding electrical problem. The dependence of the electroosmotic conductance on pore radius, Debye length and membrane thickness is investigated. Reference: Supported by the NIH under Grant 4R01HG004842. SG acknowledges a visiting professorship at Cambridge University funded by the Leverhulme Trust, UK. JDS thanks DAMTP (Cambridge University) and Institut de Mecanique des Fluides de Toulouse for hospitality.

  20. Environmental Green Chemistry Applications of Nanoporous Carbons

    Energy Technology Data Exchange (ETDEWEB)

    Matos, J.; Garcia, A; Poon, P

    2010-01-01

    Influence of surface properties of nanoporous carbons on activity and selectivity during the photooxidation of 4-chlorophenol on UV-irradiated TiO{sub 2} was performed. Characterization by infrared spectroscopy, X-ray photoelectronic spectroscopy and X-ray absorption near edge structure spectroscopy confirm the presence of a contact interface between both solids and suggest the coordination of some functional organic groups of the carbon surface, mainly ethers and carboxylic acids, to metallic centre Ti{sup +4} in TiO{sub 2}. Changes in surface pH of carbons from basic to neutral or acid remarkably increase the production of 4-chlorocathecol by a factor of 22 on TiO{sub 2}-Carbon in comparison of TiO{sub 2} alone. A scheme of interaction between TiO{sub 2} and carbon is proposed to the increased photoactivity of TiO{sub 2} and a reaction mechanism for the different intermediate products detected is also proposed. Results showed that TiO{sub 2}-Carbon can be used as an alternative photocatalyst for environmental green chemistry and selective organic synthesis applications.

  1. Diffusive Silicon Nanopore Membranes for Hemodialysis Applications.

    Directory of Open Access Journals (Sweden)

    Steven Kim

    Full Text Available Hemodialysis using hollow-fiber membranes provides life-sustaining treatment for nearly 2 million patients worldwide with end stage renal disease (ESRD. However, patients on hemodialysis have worse long-term outcomes compared to kidney transplant or other chronic illnesses. Additionally, the underlying membrane technology of polymer hollow-fiber membranes has not fundamentally changed in over four decades. Therefore, we have proposed a fundamentally different approach using microelectromechanical systems (MEMS fabrication techniques to create thin-flat sheets of silicon-based membranes for implantable or portable hemodialysis applications. The silicon nanopore membranes (SNM have biomimetic slit-pore geometry and uniform pores size distribution that allow for exceptional permeability and selectivity. A quantitative diffusion model identified structural limits to diffusive solute transport and motivated a new microfabrication technique to create SNM with enhanced diffusive transport. We performed in vitro testing and extracorporeal testing in pigs on prototype membranes with an effective surface area of 2.52 cm2 and 2.02 cm2, respectively. The diffusive clearance was a two-fold improvement in with the new microfabrication technique and was consistent with our mathematical model. These results establish the feasibility of using SNM for hemodialysis applications with additional scale-up.

  2. Rapid, Simultaneous Multianalyte Detection with a Nanopore

    Science.gov (United States)

    Kasianowicz, John; Henrickson, Sarah; Robertson, Baldwin; Weetall, Howard

    2000-03-01

    The ability to rapidly and simultaneously quantitate many analytes represents the next frontier in sensing. This capability would have a great impact on the cost and feasibility of analyzing blood, detecting pathogens and toxins in drinking water as well as chemical and biological warfare agents. In addition to performing transport and defense functions in cells and organelles, pore-forming proteins (ionic channels) act as sensors by converting the concentration of an analyte into a change in the pore’s conductance. Recently, several groups, including ours, suggested that channels placed in artificial membranes might prove useful for detecting analytes. Unfortunately, molecules that alter native channel conductance are limited to a small number of highly specific classes (e.g. neurotransmitters, anesthetics, protons or deuterium ions). Thus, steps towards adapting channels for more generalized analyte detection have placed recognition sites inside a channel, adjacent to the pore’s mouth or well outside the pore. We demonstrated that a wide variety of analytes could be simultaneously detected by a simpler system. Instead of attaching the recognition element inside a narrow channel, it is covalently linked to a polymer that threads completely through a nanopore.

  3. Thermal Stability of Nanoporous Raney Gold Catalyst

    Directory of Open Access Journals (Sweden)

    Matthew C. Tai

    2015-07-01

    Full Text Available Nanoporous “Raney gold” sponge was prepared by de-alloying an Au-Al precursor alloy. Catalytic tests using a micro-reactor confirmed that Raney gold can serve as an active heterogeneous catalyst for CO oxidation, reduction of NO to N2, and oxidation of NO to NO2. In general, the specific surface area of a heterogeneous catalyst has an influence on its catalytic efficacy. Unfortunately, gold sponges coarsen readily, leading to sintering of their structure and reduction in surface area. This potentially places constraints on their upper operating temperature in catalytic reactors. Here we analyzed the behavior of Raney gold when the temperature was raised. We examined the kinetics and mechanism of coarsening of the sponge using a combination of in situ optical measurements and Metropolis Monte Carlo modeling with a Lennard-Jones interatomic potential. Modeling showed that the sponges started with an isotropic “foamy” morphology with negative average “mean curvature” but that subsequent thermally activated coarsening will drive the morphology through a bi-continuous fibrous state and on, eventually, to a sponge consisting of sintered blobs of predominantly positive “mean curvature”.

  4. Structure-dependent water transport across nanopores of carbon nanotubes: toward selective gating upon temperature regulation.

    Science.gov (United States)

    Zhao, Kuiwen; Wu, Huiying

    2015-04-28

    Determining water structure in nanopores and its influence on water transport behaviour is of great importance for understanding and regulating the transport across nanopores. Here we report an ultrafast-slow flow transition phenomenon for water transport across nanopores of carbon nanotubes owing to the change in water structure in nanopores induced by temperature. By performing extensive molecular dynamics simulations, we show the dependence of water transport behaviours on water structures. Our results indicate that owing to the change in water structure in nanopores, water flux across nanopores with certain pore sizes decreases sharply (nearly 3 orders of magnitude) with the decreasing temperature. This phenomenon is very sensitive to the pore size. The threshold temperatures for the occurrence of the ultrafast-slow flow transition for water transport are also determined for various pore sizes. These findings suggest a novel protocol for selective gating of water and proton conduction across nanopores and temperature-controlled drug release.

  5. Wet-chemical enzymatic preparation and characterization of ultrathin gold-decorated single glass nanopore.

    Science.gov (United States)

    He, Haili; Xu, Xiaolong; Jin, Yongdong

    2014-05-20

    The conical glass nanopore was modified through layer-by-layer electrostatic deposition of a monolayer of glucose oxidase, and then an ultrathin gold film was formed in situ through enzyme-catalyzed reactions. The morphology and components of single glass nanopore before and after ultrathin Au deposition were characterized by transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis, respectively. In particular, the quenching of the quantum dots fluorescence in the nanopore tip zone further illustrated that the gold nanofilm was successfully deposited on the inner wall of the single glass nanopore. The Au thin films make the glass nanopores more biologically friendly and allow the nanopores facile functionalization of the surface through the Au-S bonds. For instance, the ionic current rectification (ICR) properties of the gold-decorated glass nanopores could be switched readily at different pHs by introducing different thiol molecules.

  6. Influence of nanopore surface charge and magnesium ion on polyadenosine translocation.

    Science.gov (United States)

    Lepoitevin, Mathilde; Coulon, Pierre Eugène; Bechelany, Mikhael; Cambedouzou, Julien; Janot, Jean-Marc; Balme, Sebastien

    2015-04-10

    We investigate the influence of a nanopore surface state and the addition of Mg(2+) on poly-adenosine translocation. To do so, two kinds of nanopores with a low aspect ratio (diameter ∼3-5 nm, length 30 nm) were tailored: the first one with a negative charge surface and the second one uncharged. It was shown that the velocity and the energy barrier strongly depend on the nanopore surface. Typically if the nanopore and polyA exhibit a similar charge, the macromolecule velocity increases and its global energy barrier of entrance in the nanopore decreases, as opposed to the non-charged nanopore. Moreover, the addition of a divalent chelating cation induces an increase of energy barrier of entrance, as expected. However, for a negative nanopore, this effect is counterbalanced by the inversion of the surface charge induced by the adsorption of divalent cations.

  7. Substrate Dependent Ad-Atom Migration on Graphene and the Impact on Electron-Beam Sculpting Functional Nanopores.

    Science.gov (United States)

    Freedman, Kevin J; Goyal, Gaurav; Ahn, Chi Won; Kim, Min Jun

    2017-05-10

    The use of atomically thin graphene for molecular sensing has attracted tremendous attention over the years and, in some instances, could displace the use of classical thin films. For nanopore sensing, graphene must be suspended over an aperture so that a single pore can be formed in the free-standing region. Nanopores are typically drilled using an electron beam (e-beam) which is tightly focused until a desired pore size is obtained. E-beam sculpting of graphene however is not just dependent on the ability to displace atoms but also the ability to hinder the migration of ad-atoms on the surface of graphene. Using relatively lower e-beam fluxes from a thermionic electron source, the C-atom knockout rate seems to be comparable to the rate of carbon ad-atom attraction and accumulation at the e-beam/graphene interface (i.e., Rknockout ≈ Raccumulation). Working at this unique regime has allowed the study of carbon ad-atom migration as well as the influence of various substrate materials on e-beam sculpting of graphene. We also show that this information was pivotal to fabricating functional graphene nanopores for studying DNA with increased spatial resolution which is attributed to atomically thin membranes.

  8. Modeling sorption and diffusion of organic sorbate in hexadecyltrimethylammonium-modified clay nanopores - a molecular dynamics simulation study.

    Science.gov (United States)

    Zhao, Qian; Burns, Susan E

    2013-03-19

    Organoclays are highly sorptive engineered materials that can be used as amendments in barrier systems or geosynthetic liners. The performance of confining and isolating the nonpolar organic contaminants by those barrier/lining systems is essentially controlled by the process of organic contaminant mass transport in nanopores of organoclays. In this article, we use molecular dynamics (MD) simulations to study the sorption and diffusion of organic sorbates in interlayers of sodium montmorillonite and hexadecyltrimethylammonium (HDTMA(+))-modified montmorillonite clays. Simulated system consisted of the clay framework, interlayer organic cation, water, and organic sorbate. Their interactions were addressed by the combined force field of ClayFF, constant-valence force field, and SPC water model. Simulation results indicated that in HDTMA coated clay nanopores, diffusion of nonpolar species benzene was slowed because they were subjected to influence of both the pore wall and the HDTMA surfactant. This suggested the nonpolar organic compound diffusion in organophilic clays can be affected by molecular size of diffusive species, clay pore size, and organic surfactant loading. Additionally, a model that connected the diffusion rate of organic compounds in the bulk organoclay matrix with macropores and nanopores was established. The impact of intercalated organic cations on the diffusion dominated mass transport of organic compounds yielded insight into the prediction of the apparent diffusion behavior of organic compounds in organic-modified clays.

  9. 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.

  10. Impedance spectroscopy of highly ordered nano-porous electrodes based on Au-AAO (anodic aluminum oxide) structure.

    Science.gov (United States)

    Ahn, Jaehwan; Cho, Sungbo; Min, Junhong

    2013-11-01

    Electrochemical measurements using the microelectrodes are increasingly utilized for the label-free detection of the small amount of biological materials such as DNA, protein, and cells. However, the interfacial electrode impedance increases and may hinder the detection of weak signals as the size of electrode decreases. To enhance the measurement sensitivity while reducing the electrode size, in this study, microelectrodes employing a nanoporous structure were fabricated and characterized by using electrical impedance spectroscopy. We made the highly ordered honeycomb nanoporous structure of Anodic Aluminum Oxide (AAO) by electrochemical anodizing and formed Au layer on the surface of AAO (Au/AAO) by electroless Au plating method. The electrical characteristics of the fabricated Au/AAO electrodes were evaluated by using de Levie's model derived for the pore electrodes. As a result, the interfacial electrode impedance of the fabricated Au/AAO electrodes was 2-3 order lower than the value of the planar electrodes at frequencies below 1 kHz. It implies this nanoporous electrode could be directly applied to label free detection of biomaterials.

  11. Pharmacokinetic properties of new antitumor radiopharmaceutical on the basis of diamond nanoporous composites labeled with rhenium-188

    Science.gov (United States)

    Petriev, V. M.; Tishchenko, V. K.; Kuril’chik, A. A.; Skvortsov, V. G.

    2017-01-01

    Today the development of address therapeutic radionuclide delivery systems directly to tumor tissue is of current interest. It can be achieved by the design of drug containers of specific sizes and shapes from carbon-based composite materials. It will be allowed to enhance the efficacy of anticancer therapy and avoid serious side effects. In this work we studied the pharmacokinetic properties of nanodiamond nanoporous composite labeled with rhenium-188 in rats with hepatocholangioma PC-1 after intratumoral injection. It was established that substantial part of injected radioactivity remained in tumor tissue. Within three hours after 188Re-nanoporous composites injection activity in tumor constituted 79.1–91.3% of injected dose (ID). Then activity level declined to 45.9% ID at 120 hours. No more than 1.34% ID entered the bloodstream. In soft organs and tissues, except thyroid gland, the content of compound didn’t exceed 0.3% ID/g. The highest activity in thyroid gland was 6.95% ID/g. In conclusion, received results suggest 188Re-nanoporous composites can be promising radionuclide delivery systems for cancer treatment.

  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. Raman fingerprinting of single dielectric nanoparticles in plasmonic nanopores

    Science.gov (United States)

    Kerman, Sarp; Chen, Chang; Li, Yi; van Roy, Wim; Lagae, Liesbet; van Dorpe, Pol

    2015-11-01

    Plasmonic nano-apertures are commonly used for the detection of small particles such as nanoparticles and proteins by exploiting electrical and optical techniques. Plasmonic nanopores are metallic nano-apertures sitting on a thin membrane with a tiny hole. It has been shown that plasmonic nanopores with a given geometry identify internal molecules using Surface Enhanced Raman Spectroscopy (SERS). However, label-free identification of a single dielectric nanoparticle requires a highly localized field comparable to the size of the particle. Additionally, the particle's Brownian motion can jeopardize the amount of photons collected from a single particle. Here, we demonstrate that the combination of optical trapping and SERS can be used for the detection and identification of 20 nm polystyrene nanoparticles in plasmonic nanopores. This work is anticipated to contribute to the detection of small bioparticles, optical trapping and nanotribology studies.Plasmonic nano-apertures are commonly used for the detection of small particles such as nanoparticles and proteins by exploiting electrical and optical techniques. Plasmonic nanopores are metallic nano-apertures sitting on a thin membrane with a tiny hole. It has been shown that plasmonic nanopores with a given geometry identify internal molecules using Surface Enhanced Raman Spectroscopy (SERS). However, label-free identification of a single dielectric nanoparticle requires a highly localized field comparable to the size of the particle. Additionally, the particle's Brownian motion can jeopardize the amount of photons collected from a single particle. Here, we demonstrate that the combination of optical trapping and SERS can be used for the detection and identification of 20 nm polystyrene nanoparticles in plasmonic nanopores. This work is anticipated to contribute to the detection of small bioparticles, optical trapping and nanotribology studies. Electronic supplementary information (ESI) available: Fig. S1: The

  14. Direct laser writing for nanoporous liquid core laser sensors

    DEFF Research Database (Denmark)

    Grossmann, Tobias; Christiansen, Mads Brøkner; Peterson, Jeffrey

    2012-01-01

    We report the fabrication of nanoporous liquid core lasers via direct laser writing based on two-photon absorption in combination with thiolene-chemistry. As gain medium Rhodamine 6G was embedded in the nanoporous polybutadiene matrix. The lasing devices with thresholds of 19 µJ/mm2 were measured...... to have bulk refractive index sensitivities of 169 nm/RIU at a laser wavelength of 600 nm, demonstrating strongly increased overlap of the modes with the analyte in comparison to solid state evanescent wave sensors....

  15. Multilayered semiconductor membranes for nanopore ionic conductance modulation.

    Science.gov (United States)

    Gracheva, Maria E; Melnikov, Dmitriy V; Leburton, Jean-Pierre

    2008-11-25

    We explore the possibility of using thin layered semiconductor membranes for electrical control of the ion current flow through a nanopore, thereby operating like tunable ionic transistors. While single layer semiconductor membranes can be voltage tuned to operate as ionic filters or "switches", double layered membranes can rectify the ion current flowing through the nanopore in addition to ion filtering. Triple layer membranes exhibit enhanced functionality with characteristics similar to those of the single and double layer membranes in addition to bidirectional current blocking and switching, thereby operating similar to tunable ionic transistors.

  16. Synergetic effect of carbon nanopore size and surface oxidation on CO2 capture from CO2/CH4 mixtures.

    Science.gov (United States)

    Furmaniak, Sylwester; Kowalczyk, Piotr; Terzyk, Artur P; Gauden, Piotr A; Harris, Peter J F

    2013-05-01

    We have studied the synergetic effect of confinement (carbon nanopore size) and surface chemistry (the number of carbonyl groups) on CO2 capture from its mixtures with CH4 at typical operating conditions for industrial adsorptive separation (298 K and compressed CO2-CH4 mixtures). Although both confinement and surface oxidation have an impact on the efficiency of CO2/CH4 adsorptive separation at thermodynamics equilibrium, we show that surface functionalization is the most important factor in designing an efficient adsorbent for CO2 capture. Systematic Monte Carlo simulations revealed that adsorption of CH4 either pure or mixed with CO2 on oxidized nanoporous carbons is only slightly increased by the presence of functional groups (surface dipoles). In contrast, adsorption of CO2 is very sensitive to the number of carbonyl groups, which can be examined by a strong electric quadrupolar moment of CO2. Interestingly, the adsorbed amount of CH4 is strongly affected by the presence of the co-adsorbed CO2. In contrast, the CO2 uptake does not depend on the molar ratio of CH4 in the bulk mixture. The optimal carbonaceous porous adsorbent used for CO2 capture near ambient conditions should consist of narrow carbon nanopores with oxidized pore walls. Furthermore, the equilibrium separation factor was the greatest for CO2/CH4 mixtures with a low CO2 concentration. The maximum equilibrium separation factor of CO2 over CH4 of ~18-20 is theoretically predicted for strongly oxidized nanoporous carbons. Our findings call for a review of the standard uncharged model of carbonaceous materials used for the modeling of the adsorption separation processes of gas mixtures containing CO2 (and other molecules with strong electric quadrupolar moment or dipole moment).

  17. Molecular transport through nanoporous silicon nitride membranes produced from self-assembling block copolymers.

    Science.gov (United States)

    Montagne, Franck; Blondiaux, Nicolas; Bojko, Alexandre; Pugin, Raphaël

    2012-09-28

    To achieve fast and selective molecular filtration, membrane materials must ideally exhibit a thin porous skin and a high density of pores with a narrow size distribution. Here, we report the fabrication of nanoporous silicon nitride membranes (NSiMs) at the full wafer scale using a versatile process combining block copolymer (BCP) self-assembly and conventional photolithography/etching techniques. In our method, self-assembled BCP micelles are used as templates for creating sub-100 nm nanopores in a thin low-stress silicon nitride layer, which is then released from the underlying silicon wafer by etching. The process yields 100 nm thick free-standing NSiMs of various lateral dimensions (up to a few mm(2)). We show that the membranes exhibit a high pore density, while still retaining excellent mechanical strength. Permeation experiments reveal that the molecular transport rate across NSiMs is up to 16-fold faster than that of commercial polymeric membranes. Moreover, using dextran molecules of various molecular weights, we also demonstrate that size-based separation can be achieved with a very good selectivity. These new silicon nanosieves offer a relevant technological alternative to commercially available ultra- and microfiltration membranes for conducting high resolution biomolecular separations at small scales.

  18. On-Chip Supercapacitor Electrode Based On Polypyrrole Deposited Into Nanoporous Au Scaffold

    Science.gov (United States)

    Lu, P.; Ohlckers, P.; Chen, X. Y.

    2016-11-01

    On-chip supercapacitors hold the potential promise for serving as the energy storage units in integrated circuit system, due to their much higher energy density in comparison with conventional dielectric capacitors, high power density and long-term cycling stability. In this study, nanoporous Au (NP-Au) film on-chip was employed as the electrode scaffold to help increase the electrolyte-accessible area for active material. Pseudo-capacitive polypyrrole (PPY) with high theoretical capacitance was deposited into the NP-Au scaffold, to construct the tailored NP-Au/PPY hybrid on-chip electrode with improved areal capacitance. Half cell test in three- electrode system revealed the improved capacitor performance of nanoporous Au supported PPY electrode, compared to the densely packed PPY nanowire film electrode on planer Au substrate (Au/PPY). The areal capacitance of 37 mF/cm2∼10 mV/s, 32 mF/cm2∼50 mV/s, 28 mF/cm2∼100 mV/s, 16 mF/cm2∼500 mV/s, were offered by NP-Au/PPY. Also, the cycling performance was enhanced via using NP-Au scaffold. The developed NP-Au/PPY on-chip electrode demonstrated herein paves a feasible pathway to employ dealloying derived porous metal as the scaffold for improving both the energy density and cycling performance for supercapacitor electrodes.

  19. Liquid crystal alignment in nanoporous anodic aluminum oxide layer for LCD panel applications.

    Science.gov (United States)

    Hong, Chitsung; Tang, Tsung-Ta; Hung, Chi-Yu; Pan, Ru-Pin; Fang, Weileun

    2010-07-16

    This paper reports the implementation and integration of a self-assembled nanoporous anodic aluminum oxide (np-AAO) film and liquid crystal (LC) on an ITO-glass substrate for liquid crystal display (LCD) panel applications. An np-AAO layer with a nanopore array acts as the vertical alignment layer to easily and uniformly align the LC molecules. Moreover, the np-AAO nanoalignment layer provides outstanding material properties, such as being inorganic with good transmittance, and colorless on ITO-glass substrates. In this application, an LCD panel, with the LC on the np-AAO nanoalignment layer, is successfully implemented on an ITO-glass substrate, and its performance is demonstrated. The measurements show that the LCD panel, consisting of an ITO-glass substrate and an np-AAO layer, has a transmittance of 60-80%. In addition, the LCD panel switches from a black state to a bright state at 3 V(rms), with a response time of 62.5 ms. In summary, this paper demonstrates the alignment of LC on an np-AAO layer for LCD applications.

  20. Oxide-based inorganic/organic and nanoporous spherical particles: synthesis and functional properties

    Directory of Open Access Journals (Sweden)

    Kota Shiba, Motohiro Tagaya, Richard D Tilley and Nobutaka Hanagata

    2013-01-01

    Full Text Available This paper reviews the recent progress in the preparation of oxide-based and heteroatom-doped particles. Surfactant-templated oxide particles, e.g. silica and titania, are possible candidates for various potential applications such as adsorbents, photocatalysts, and optoelectronic and biological materials. We highlight nanoporous oxides of one element, such as silicon or titanium, and those containing multiple elements, which exhibit properties that are not achieved with individual components. Although the multicomponent nanoporous oxides possess a number of attractive functions, the origin of their properties is hard to determine due to compositional/structural complexity. Particles with a well-defined size and shape are keys for a quantitative and detailed discussion on the unique complex properties of the particles. From this viewpoint, we review the synthesis techniques of the oxide particles, which are functionalized with organic molecules or doped with heteroatoms, the physicochemical properties of the particles and the possibilities for their photofunctional applications as complex systems.

  1. Single-layer MoS2 nanopores as nanopower generators

    Science.gov (United States)

    Feng, Jiandong; Graf, Michael; Liu, Ke; Ovchinnikov, Dmitry; Dumcenco, Dumitru; Heiranian, Mohammad; Nandigana, Vishal; Aluru, Narayana R.; Kis, Andras; Radenovic, Aleksandra

    2016-08-01

    Making use of the osmotic pressure difference between fresh water and seawater is an attractive, renewable and clean way to generate power and is known as ‘blue energy’. Another electrokinetic phenomenon, called the streaming potential, occurs when an electrolyte is driven through narrow pores either by a pressure gradient or by an osmotic potential resulting from a salt concentration gradient. For this task, membranes made of two-dimensional materials are expected to be the most efficient, because water transport through a membrane scales inversely with membrane thickness. Here we demonstrate the use of single-layer molybdenum disulfide (MoS2) nanopores as osmotic nanopower generators. We observe a large, osmotically induced current produced from a salt gradient with an estimated power density of up to 106 watts per square metre—a current that can be attributed mainly to the atomically thin membrane of MoS2. Low power requirements for nanoelectronic and optoelectric devices can be provided by a neighbouring nanogenerator that harvests energy from the local environment—for example, a piezoelectric zinc oxide nanowire array or single-layer MoS2 (ref. 12). We use our MoS2 nanopore generator to power a MoS2 transistor, thus demonstrating a self-powered nanosystem.

  2. Crystal-Size-Dependent Structural Transitions in Nanoporous Crystals: Adsorption-Induced Transitions in ZIF-8

    KAUST Repository

    Zhang, Chen

    2014-09-04

    © 2014 American Chemical Society. Understanding the crystal-size dependence of both guest adsorption and structural transitions of nanoporous solids is crucial to the development of these materials. We find that nano-sized metal-organic framework (MOF) crystals have significantly different guest adsorption properties compared to the bulk material. A new methodology is developed to simulate the adsorption and transition behavior of entire MOF nanoparticles. Our simulations predict that the transition pressure significantly increases with decreasing particle size, in agreement with crystal-size-dependent experimental measurements of the N2-ZIF-8 system. We also propose a simple core-shell model to examine this effect on length scales that are inaccessible to simulations and again find good agreement with experiments. This study is the first to examine particle size effects on structural transitions in ZIFs and provides a thermodynamic framework for understanding the underlying mechanism.

  3. Emergence of Zeolite Analogs and other Microporous Crystals in an Atomic Lattice Model of Silica and Related Materials.

    Science.gov (United States)

    Jin, Lin; Auerbach, Scott M; Monson, Peter A

    2012-03-15

    The potential of tailored nanopores to transform technologies such as drug delivery, biofuel production, and optical-electronic devices depends on fundamental knowledge of the self-assembly of ordered nanoporous solids. Atomic-level geometries of critical nuclei that lead to such solids have remained hidden in the nanoscale blind spot between local (5 nm) probes of structure. Heroic efforts at molecular simulation of nanopore formation have provided massive libraries of hypothetical structures; (1-5) however, to date no statistical simulation has generated a crystallization pathway from random initial condition to ordered nanoporous solid, until now. In this work, we show that a recently developed atomic lattice model of silica and related materials can form ordered nanoporous solids with a rich variety of structures including known chalcogenides, zeolite analogs, and layered materials. We find that whereas canonical Monte Carlo simulations of the model consistently produce the amorphous solids studied in our previous work, parallel tempering Monte Carlo gives rise to ordered nanoporous solids. The utility of parallel tempering highlights the existence of barriers between amorphous and crystalline phases of our model. Moreover, the self-assembly or nanoporous crystalline phases in the model open the door to detailed understanding of nanopore nucleation.

  4. Analysis of electrolyte transport through charged nanopores

    Science.gov (United States)

    Peters, P. B.; van Roij, R.; Bazant, M. Z.; Biesheuvel, P. M.

    2016-05-01

    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 relates fluxes (electrical current, salt flux, and fluid velocity) and driving forces (difference in electric potential, salt concentration, and pressure). We analyze the general case with overlapping electric double layers in the pore and a nonzero axial salt concentration gradient. The 3 ×3 matrix relating these quantities exhibits Onsager symmetry and we report a significant new simplification for the diagonal element relating axial salt flux to the gradient in chemical potential. We prove that Onsager symmetry is preserved under changes of variables, which we illustrate by transformation to a different flux-force matrix given by Gross and Osterle [J. Chem. Phys. 49, 228 (1968), 10.1063/1.1669814]. The capillary pore model is well suited to describe the nonlinear response of charged membranes or nanofluidic devices for electrokinetic energy conversion and water desalination, as long as the transverse ion profiles remain in local quasiequilibrium. As an example, we evaluate electrical power production from a salt concentration difference by reverse electrodialysis, using an efficiency versus power diagram. We show that since the capillary pore model allows for axial gradients in salt concentration, partial loops in current, salt flux, or fluid flow can develop in the pore. Predictions for macroscopic transport properties using a reduced model, where the potential and concentration are assumed to be invariant with radial coordinate ("uniform potential" or "fine capillary pore" model), are close to results of the full model.

  5. Multichannel detection of ionic currents through two nanopores fabricated on integrated Si3N4 membranes.

    Science.gov (United States)

    Yanagi, Itaru; Akahori, Rena; Aoki, Mayu; Harada, Kunio; Takeda, Ken-Ichi

    2016-08-16

    Integration of solid-state nanopores and multichannel detection of signals from each nanopore are effective measures for realizing high-throughput nanopore sensors. In the present study, we demonstrated fabrication of Si3N4 membrane arrays and the simultaneous measurement of ionic currents through two nanopores formed in two adjacent membranes. Membranes with thicknesses as low as 6.4 nm and small nanopores with diameters of less than 2 nm could be fabricated using the poly-Si sacrificial-layer process and multilevel pulse-voltage injection. Using the fabricated nanopore membranes, we successfully achieved simultaneous detection of clear ionic-current blockades when single-stranded short homopolymers (poly(dA)60) passed through two nanopores. In addition, we investigated the signal crosstalk and leakage current among separated chambers. When two nanopores were isolated on the front surface of the membrane, there was no signal crosstalk or leakage current between the chambers. However, when two nanopores were isolated on the backside of the Si substrate, signal crosstalk and leakage current were observed owing to high-capacitance coupling between the chambers and electrolysis of water on the surface of the Si substrate. The signal crosstalk and leakage current could be suppressed by oxidizing the exposed Si surface in the membrane chip. Finally, the observed ionic-current blockade when poly(dA)60 passed through the nanopore in the oxidized chip was approximately half of that observed in the non-oxidized chip.

  6. Engineering a nanopore with co-chaperonin function

    NARCIS (Netherlands)

    Ho, Ching-Wen; Meervelt, Veerle; Tsai, Keng-Chang; De Temmerman, Pieter-Jan; Mast, Jan; Maglia, Giovanni

    2015-01-01

    The emergence of an enzymatic function can reveal functional insights and allows the engineering of biological systems with enhanced properties. We engineered an alpha hemolysin nanopore to function as GroES, a protein that, in complex with GroEL, forms a two-stroke protein-folding nanomachine. The

  7. Electrochromic artificial muscles based on nanoporous metal-polymer composites

    NARCIS (Netherlands)

    Detsi, E.; Onck, P. R.; De Hosson, J. T. M.

    2013-01-01

    This work shows that a nano-coating of electrochromic polymer grown onto the ligaments of nanoporous gold causes reversible dimensional and color changes during electrochemical actuation. This combination of electromechanical and optical properties opens additional avenues for the applications of

  8. 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.

  9. Onsager coefficients for binary mixture diffusion in nanopores

    NARCIS (Netherlands)

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

    2008-01-01

    This paper presents a critical appraisal of current estimation methods for the Onsager coefficients L-11, L-22, and L-12 for binary mixture diffusion inside nanopores using pure component diffusivity data inputs. The appraisal is based on extensive sets of molecular dynamics (MD) simulation data on

  10. Nanopore sensing of individual transcription factors bound to DNA

    Science.gov (United States)

    Squires, Allison; Atas, Evrim; Meller, Amit

    2015-06-01

    Transcription factor (TF)-DNA interactions are the primary control point in regulation of gene expression. Characterization of these interactions is essential for understanding genetic regulation of biological systems and developing novel therapies to treat cellular malfunctions. Solid-state nanopores are a highly versatile class of single-molecule sensors that can provide rich information about local properties of long charged biopolymers using the current blockage patterns generated during analyte translocation, and provide a novel platform for characterization of TF-DNA interactions. The DNA-binding domain of the TF Early Growth Response Protein 1 (EGR1), a prototypical zinc finger protein known as zif268, is used as a model system for this study. zif268 adopts two distinct bound conformations corresponding to specific and nonspecific binding, according to the local DNA sequence. Here we implement a solid-state nanopore platform for direct, label- and tether-free single-molecule detection of zif268 bound to DNA. We demonstrate detection of single zif268 TFs bound to DNA according to current blockage sublevels and duration of translocation through the nanopore. We further show that the nanopore can detect and discriminate both specific and nonspecific binding conformations of zif268 on DNA via the distinct current blockage patterns corresponding to each of these two known binding modes.

  11. Evaporation-driven nanomachining to fabricate nanopores in $SIO_2$

    NARCIS (Netherlands)

    Vreede, de L.J.; Berg, van den A.; Eijkel, J.C.T.

    2014-01-01

    We demonstrate a novel method to produce high aspect ratio nanopores in fused silica (SiO2) using basic cleanroom techniques and high temperature. We found that gold nanoparticles on silicon oxide (SiO2) move perpendicularly to the surface into the substrate when heated at 1050C, creating cylindric

  12. Liquid Core Waveguides by UV Modification of Nanoporous Polymer

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Gopalakrishnan, Nimi; Sagar, Kaushal Shashikant

    2011-01-01

    Liquid core waveguides are fabricated from a self-assembled nanoporous polymer, with a porosity of 40%. The high porosity results in an effective refractive index of 1.26 for visible light, i.e. below the refractive index of aqueous solutions. However, since the polymer is hydrophobic, fluids...

  13. Template Transfer Nanoimprint for Uniform Nanopores and Nanopoles

    Directory of Open Access Journals (Sweden)

    Jianjun Li

    2016-01-01

    Full Text Available A new methodology is developed for the fabrication of nanostructures on substrate based on anodized Al2O3 (AAO porous template transfer process. It includes (1 forming amorphous alloy, negative UV-resist resin (i.e., SU-8, or PMMA (polymethylmethacrylate plate nanorod arrays by hot-press molding amorphous alloy, negative UV-resist resin (i.e., SU-8, or PMMA plate into the anodized Al2O3 porous substrates; (2 removing AAO templates by chemical etching process after suitable posttreatment (annealing and/or irradiation to improve the mechanical strength of the nanorod arrays; (3 reforming nanopore films by hot-embossing the nanorod arrays into a thin layer of polymer film on substrates (e.g., silica; (4 cleaning the bottom residues in pores of the films by oxygen plasmon. The results indicate that the diameters of amorphous alloy (or negative UV-resist resin or PMMA nanorod arrays can be ranged from 32 nm to 200 nm. The diameters of the imprinted ILR-1050 photoresist nanopores are about 94.5 ± 12.2 nm and the diameters of the imprinted or SU-8 resin on glass slides nanopores are about 207 ± 26.4 nm, which inherit the diameters of AAO templates. This methodology provides a general method to fabricate nanorods arrays and/or thin nanopore films by template transfer nanoimprint process.

  14. A Comprehensive Numerical Model for Simulating Fluid Transport in Nanopores

    Science.gov (United States)

    Zhang, Yuan; Yu, Wei; Sepehrnoori, Kamy; di, Yuan

    2017-01-01

    Since a large amount of nanopores exist in tight oil reservoirs, fluid transport in nanopores is complex due to large capillary pressure. Recent studies only focus on the effect of nanopore confinement on single-well performance with simple planar fractures in tight oil reservoirs. Its impacts on multi-well performance with complex fracture geometries have not been reported. In this study, a numerical model was developed to investigate the effect of confined phase behavior on cumulative oil and gas production of four horizontal wells with different fracture geometries. Its pore sizes were divided into five regions based on nanopore size distribution. Then, fluid properties were evaluated under different levels of capillary pressure using Peng-Robinson equation of state. Afterwards, an efficient approach of Embedded Discrete Fracture Model (EDFM) was applied to explicitly model hydraulic and natural fractures in the reservoirs. Finally, three fracture geometries, i.e. non-planar hydraulic fractures, non-planar hydraulic fractures with one set natural fractures, and non-planar hydraulic fractures with two sets natural fractures, are evaluated. The multi-well performance with confined phase behavior is analyzed with permeabilities of 0.01 md and 0.1 md. This work improves the analysis of capillarity effect on multi-well performance with complex fracture geometries in tight oil reservoirs.

  15. Nanopore fabrication by heating au particles on ceramic substrates

    NARCIS (Netherlands)

    de Vreede, Lennart; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    We found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphous Si3N4, move perpendicularly into the substrate. Dependent on applied temperatures, particles can become buried or leave nanopores of extreme aspect ratio (diameter congruent to

  16. Chemically modified solid state nanopores for high throughput nanoparticle separation

    Energy Technology Data Exchange (ETDEWEB)

    Prabhu, Anmiv S; Kim, Min Jun [School of Biomedical Engineering and Health Science, Drexel University, Philadelphia, PA 19104 (United States); Jubery, Talukder Zaki N; Dutta, Prashanta [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Freedman, Kevin J; Mulero, Rafael, E-mail: mkim@coe.drexel.ed [Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104 (United States)

    2010-11-17

    The separation of biomolecules and other nanoparticles is a vital step in several analytical and diagnostic techniques. Towards this end we present a solid state nanopore-based set-up as an efficient separation platform. The translocation of charged particles through a nanopore was first modeled mathematically using the multi-ion model and the surface charge density of the nanopore membrane was identified as a critical parameter that determines the selectivity of the membrane and the throughput of the separation process. Drawing from these simulations a single 150 nm pore was fabricated in a 50 nm thick free-standing silicon nitride membrane by focused-ion-beam milling and was chemically modified with (3-aminopropyl)triethoxysilane to change its surface charge density. This chemically modified membrane was then used to separate 22 and 58 nm polystyrene nanoparticles in solution. Once optimized, this approach can readily be scaled up to nanopore arrays which would function as a key component of next-generation nanosieving systems.

  17. Development of nanoporous gold electrodes for electrochemical applications

    DEFF Research Database (Denmark)

    Quan, Xueling; Fischer, Lee MacKenzie; Boisen, Anja

    2011-01-01

    In this work we have used simple microfabrication techniques and chemical de-alloying of co-sputtered AgAu alloys to create nanoporous gold (np-Au) electrodes. The physical properties of the np-Au electrodes were investigated using scanning electron microscopy with energy dispersive X-ray analysi...

  18. Nanopore Sequencing as a Rapidly Deployable Ebola Outbreak Tool.

    Science.gov (United States)

    Hoenen, Thomas; Groseth, Allison; Rosenke, Kyle; Fischer, Robert J; Hoenen, Andreas; Judson, Seth D; Martellaro, Cynthia; Falzarano, Darryl; Marzi, Andrea; Squires, R Burke; Wollenberg, Kurt R; de Wit, Emmie; Prescott, Joseph; Safronetz, David; van Doremalen, Neeltje; Bushmaker, Trenton; Feldmann, Friederike; McNally, Kristin; Bolay, Fatorma K; Fields, Barry; Sealy, Tara; Rayfield, Mark; Nichol, Stuart T; Zoon, Kathryn C; Massaquoi, Moses; Munster, Vincent J; Feldmann, Heinz

    2016-02-01

    Rapid sequencing of RNA/DNA from pathogen samples obtained during disease outbreaks provides critical scientific and public health information. However, challenges exist for exporting samples to laboratories or establishing conventional sequencers in remote outbreak regions. We successfully used a novel, pocket-sized nanopore sequencer at a field diagnostic laboratory in Liberia during the current Ebola virus outbreak.

  19. Water and Ion Permeation through Electrically Charged Nanopore

    Institute of Scientific and Technical Information of China (English)

    ZENG Li; ZUO Guang-Hong; GONG Xiao-Jing; LU Hang-Jun; WANG Chun-Lei; WU Ke-Fei; WAN Rong-Zheng

    2008-01-01

    @@ The behaviour of water and small solutes in confined geometries is important to a variety of chemical and nanofluidic applications. Here we investigate the permeation and distribution of water and ions in electrically charged carbon cylindrical nanopore during the osmotic process using molecular dynamics simulations. In the simulations, charges are distributed uniformly on the pores with diameter of 0.9 nm. For nanopores with no charge or a low charge, ions are difficult to enter. With the increasing of charge densities on the pores, ions will appear inside the nanopores because of the large electronic forces between the ions and the charged pores. Different ion entries induce varying effects on osmotic water flow. Our simulations reveal that the osmotic water can flow through the negatively charged pore occupied by K+ ions, while water flux through the positively charged pores will be disrupted by Cl- ions inside the pores. This may be explained by the different radial distributions of K+ions and Cl- ions inside the charged nanopores.

  20. Electrochromic artificial muscles based on nanoporous metal-polymer composites

    NARCIS (Netherlands)

    Detsi, E.; Onck, P. R.; De Hosson, J. T. M.

    2013-01-01

    This work shows that a nano-coating of electrochromic polymer grown onto the ligaments of nanoporous gold causes reversible dimensional and color changes during electrochemical actuation. This combination of electromechanical and optical properties opens additional avenues for the applications of ar