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Sample records for pyrolysed nanoporous structure

  1. Three-dimensional structures of magnesium nanopores

    NASA Astrophysics Data System (ADS)

    Wu, Shujing; Zheng, He; Jia, Shuangfeng; Sheng, Huaping; Cao, Fan; Li, Lei; Hu, Shuaishuai; Zhao, Penghui; Zhao, Dongshan; Wang, Jianbo

    2016-03-01

    The optimization of nanopore-based devices is closely related to the nanopore three-dimensional (3D) structures. In this paper, faceted nanopores were fabricated in magnesium (Mg) by aligning the electron beam (e-beam) along the [0001] direction. Detailed structural characterization by transmission electron microscopy reveals the existence of two 3D structures: hexagonal prism-shaped and hourglass-shaped 3D morphologies. Moreover, the 3D structures of nanopores are also found to depend on the widest nanopore diameter-to-thickness ratio (D/t). A plausible formation mechanism for different 3D structures is discussed. Our results incorporate a critical piece of information regarding the nanopore 3D structures in Mg and may serve as an important design guidance for the size- and shape-controllable fabrication of solid-state nanopores applying the e-beam sculpting technique.

  2. Effect of Pretreatment on Biomass Residue Structure and the Application of Pyrolysed and Composted Biomass Residues in Soilless Culture

    PubMed Central

    Suo, Linna; Sun, Xiangyang; Jiang, Weijie

    2013-01-01

    The changes in the structural characteristics of biomass residues during pyrolysis and composting were investigated. The biomass residues particles were prepared by pyrolysing at temperatures ranging from 350 to 400. For soilless production of the ornamental plant Anthurium andraeanum, pure sphagnum peat moss (P) has traditionally been used as the growing medium. This use of P must be reduced, however, because P is an expensive and nonrenewable resource. The current study investigated the use of biomass residues as substitutes for P in A. andraeanum production. Plants were grown for 15 months in 10 soilless media that contained different proportions of pyrolysed corn cobs (PC), composted corn cobs (C), pyrolysed garden wastes (PG), and P. Although the media altered the plant nutrient content, A. andraeanum growth, development, and yield were similar with media consisting of 50% P+50% PC, 50% P+35% PC+15% PG, and 100% P. This finding indicates that, when pyrolysed, organic wastes, which are otherwise an environmental problem, can be used to reduce the requirement for peat in the soilless culture of A. andraeanum. PMID:23704995

  3. Nanopore sequencing detects structural variants in cancer.

    PubMed

    Norris, Alexis L; Workman, Rachael E; Fan, Yunfan; Eshleman, James R; Timp, Winston

    2016-03-01

    Despite advances in sequencing, structural variants (SVs) remain difficult to reliably detect due to the short read length (<300 bp) of 2nd generation sequencing. Not only do the reads (or paired-end reads) need to straddle a breakpoint, but repetitive elements often lead to ambiguities in the alignment of short reads. We propose to use the long-reads (up to 20 kb) possible with 3rd generation sequencing, specifically nanopore sequencing on the MinION. Nanopore sequencing relies on a similar concept to a Coulter counter, reading the DNA sequence from the change in electrical current resulting from a DNA strand being forced through a nanometer-sized pore embedded in a membrane. Though nanopore sequencing currently has a relatively high mismatch rate that precludes base substitution and small frameshift mutation detection, its accuracy is sufficient for SV detection because of its long reads. In fact, long reads in some cases may improve SV detection efficiency. We have tested nanopore sequencing to detect a series of well-characterized SVs, including large deletions, inversions, and translocations that inactivate the CDKN2A/p16 and SMAD4/DPC4 tumor suppressor genes in pancreatic cancer. Using PCR amplicon mixes, we have demonstrated that nanopore sequencing can detect large deletions, translocations and inversions at dilutions as low as 1:100, with as few as 500 reads per sample. Given the speed, small footprint, and low capital cost, nanopore sequencing could become the ideal tool for the low-level detection of cancer-associated SVs needed for molecular relapse, early detection, or therapeutic monitoring. PMID:26787508

  4. Nanopore sequencing detects structural variants in cancer

    PubMed Central

    Norris, Alexis L.; Workman, Rachael E.; Fan, Yunfan; Eshleman, James R.; Timp, Winston

    2016-01-01

    ABSTRACT Despite advances in sequencing, structural variants (SVs) remain difficult to reliably detect due to the short read length (<300 bp) of 2nd generation sequencing. Not only do the reads (or paired-end reads) need to straddle a breakpoint, but repetitive elements often lead to ambiguities in the alignment of short reads. We propose to use the long-reads (up to 20 kb) possible with 3rd generation sequencing, specifically nanopore sequencing on the MinION. Nanopore sequencing relies on a similar concept to a Coulter counter, reading the DNA sequence from the change in electrical current resulting from a DNA strand being forced through a nanometer-sized pore embedded in a membrane. Though nanopore sequencing currently has a relatively high mismatch rate that precludes base substitution and small frameshift mutation detection, its accuracy is sufficient for SV detection because of its long reads. In fact, long reads in some cases may improve SV detection efficiency. We have tested nanopore sequencing to detect a series of well-characterized SVs, including large deletions, inversions, and translocations that inactivate the CDKN2A/p16 and SMAD4/DPC4 tumor suppressor genes in pancreatic cancer. Using PCR amplicon mixes, we have demonstrated that nanopore sequencing can detect large deletions, translocations and inversions at dilutions as low as 1:100, with as few as 500 reads per sample. Given the speed, small footprint, and low capital cost, nanopore sequencing could become the ideal tool for the low-level detection of cancer-associated SVs needed for molecular relapse, early detection, or therapeutic monitoring. PMID:26787508

  5. Block copolymer structures in nano-pores

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Guo, Xiaohu; Zvelindovsky, Andrei

    2010-03-01

    We present results of coarse-grained computer modelling of block copolymer systems in cylindrical and spherical nanopores on Cell Dynamics Simulation. We study both cylindrical and spherical pores and systematically investigate structures formed by lamellar, cylinders and spherical block copolymer systems for various pore radii and affinity of block copolymer blocks to the pore walls. The obtained structures include: standing lamellae and cylinders, ``onions,'' cylinder ``knitting balls,'' ``golf-ball,'' layered spherical, ``virus''-like and mixed morphologies with T-junctions and U-type defects [1]. Kinetics of the structure formation and the differences with planar films are discussed. Our simulations suggest that novel porous nano-containers can be formed by confining block copolymers in pores of different geometries [1,2]. [4pt] [1] M. Pinna, X. Guo, A.V. Zvelindovsky, Polymer 49, 2797 (2008).[0pt] [2] M. Pinna, X. Guo, A.V. Zvelindovsky, J. Chem. Phys. 131, 214902 (2009).

  6. 3-D simulation of nanopore structure for DNA sequencing.

    PubMed

    Park, Jun-Mo; Pak, Y Eugene; Chun, Honggu; Lee, Jong-Ho

    2012-07-01

    In this paper, we propose a method for simulating nanopore structure by using conventional 3-D simulation tool to mimic the I-V behavior of the nanopore structure. In the simulation, we use lightly doped silicon for ionic solution where some parameters like electron affinity and dielectric constant are fitted to consider the ionic solution. By using this method, we can simulate the I-V behavior of nanopore structure depending on the location and the size of the sphere shaped silicon oxide which is considered to be an indicator of a DNA base. In addition, we simulate an Ionic Field Effect Transistor (IFET) which has basically the nanopore structure, and show that the simulated curves follow sufficiently the I-V behavior of the measurement data. Therefore, we think it is reasonable to apply parameter modeling mentioned above to simulate nanopore structure. The key idea is to modify electron affinity of silicon which is used to mimic the KCl solution to avoid band bending and depletion inside the nanopore. We could efficiently utilize conventional 3-D simulation tool to simulate the I-V behavior of nanopore structures. PMID:22966538

  7. Substituted hydroxyphenanthrenes in opium pyrolysates implicated in oesophageal cancer in Iran: structures and in vitro metabolic activation of a novel class of mutagens.

    PubMed

    Friesen, M; O'Neill, I K; Malaveille, C; Garren, L; Hautefeuille, A; Bartsch, H

    1987-10-01

    Previous epidemiological and laboratory studies have indicated an association between the ingestion of opium pyrolysates, dietary deficiencies and the high incidence of oesophageal cancer in subjects in north-east Iran. Pyrolysates of opium, and particularly of morphine, a major opium alkaloid, were both shown to contain similar highly mutagenic substances that were also clastogenic in mammalian cells and which transformed hamster embryo cells in culture. We now report the isolation and characterization of nine of the most abundant mutagenic compounds present in morphine pyrolysates, using h.p.l.c, GC-MS and n.m.r. spectroscopy. The hitherto unknown compounds, all containing a hydroxyphenanthrene moiety, were identified as: I, 3-methyl-3H-naphth[1,2-e]indol-10-ol; II, 1,2-dihydro-3-methyl-3H-naphth[1,2-e]indol-10-ol; III, 1-methyl-1H-naphth[2,1-g]indol-10-ol; IV, 2-methylphenanthro[3,4-d]-[1,3]oxazol-10-ol; V, 6-methylaminophenanthren-3-ol; VI, 2-methyl-3H-phenanthro[3,4-d]imidazol-10-ol; VII, 1,2-dimethyl-1H-phenanthro[3,4-d]imidazol-10-ol; VIII, 2,5-dimethyl-3H-phenanthro[3,4-d]imidazol-10-ol; and IX, 2-ethyl-3H-phenanthro[3,4-d]imidazol-10-ol. Structures for the heterocyclic rings of compounds IV and VI to IX are tentative. Mutagenicity in Salmonella typhimurium TA98 in the presence of rat liver homogenates increased in the order listed and ranged over four orders of magnitude, IX being 1000 times more active than benzo[a]pyrene. Compounds I and VII were converted by rat liver 9000 g supernatant into phenols and dihydrodiols, implicating arene oxides as ultimate mutagens. The formation and reaction of these arene oxides was shown by trapping experiments in vitro with ethanethiol and subsequent characterization of the ethyl sulfide reaction products. The order of biological activity of compounds I-IX, dependent on the structure of the heterocyclic ring, suggests that carbocations, resonance-stabilized as quinone methides, are their ultimate reactive metabolites

  8. Structure-dependent water transport across nanopores of carbon nanotubes: toward selective gating upon temperature regulation.

    PubMed

    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. PMID:25805425

  9. ZnO Nanoporous Structure Growth, Optical and Structural Characterization by Aqueous Solution Route

    NASA Astrophysics Data System (ADS)

    Kashif, M.; Ali, Syed M. Usman; Foo, K. L.; Hashim, U.; Willander, Magnus

    2011-05-01

    In this study, we have demonstrated the structural and optical characterization of ZnO nanoporous structure grown on gold coated plastic substrate using low temperature aqueous chemical growth (ACG) technique and the annealing temperature was kept at 150° C. ZnO nanoporous structures were fabricated using hydrolysis process by reacting zinc acetate dehydrate with anhydrous ethanol. The crystalline morphology of ZnO nanoporous structures were investigated by using X-ray diffraction (XRD), surface morphology was observed by field emission scanning electron microscope (FESEM). The optical characteristics of ZnO nanoporous structures were investigated at room temperature, PL was observed using UV-Vis Spectrophotometer and the chemical composition is analyzed using Fourier Transform Infra-Red spectrometer (FTIR).

  10. Exposure to laser radiation for creation of metal materials nanoporous structures

    NASA Astrophysics Data System (ADS)

    Murzin, Serguei P.

    2013-06-01

    Exposure to laser radiation for creation of nanoporous structures in the Cu-Zn alloy was investigated. It was established that exposure to laser pulse-periodic radiation with pulse repetition rate up to 5000 Hz makes it possible to form a nanoporous structure in the near-surface layer. The conditions of increase of area depth of such structures formation up to 40-45 μm were ascertained. The temperature and speed conditions which provide predominant channel-type nanopores formation with width of about 100 nm forming a nanoporous net were determined. This patented technology is a perspective for production of catalysts and microfiltration membranes.

  11. Bacteria repelling on highly-ordered alumina-nanopore structures

    PubMed Central

    Kim, Sunghan; Cirillo, Jeffrey D.; Polycarpou, Andreas A.; Liang, Hong

    2015-01-01

    Bacteria introduce diseases and infections to humans by their adherence to biomaterials, such as implants and surgical tools. Cell desorption is an effective step to reduce such damage. Here, we report mechanisms of bacteria desorption. An alumina nanopore structure (ANS) with pore size of 35 nm, 55 nm, 70 nm, and 80 nm was used as substrate to grow Escherichia coli (E. coli) cells. A bacteria repelling experimental method was developed to quantitatively evaluate the area percentage of adherent bacterial cells that represent the nature of cell adhesion as well as desorption. Results showed that there were two crucial parameters: contact angle and contact area that affect the adhesion/desorption. The cells were found to be more easily repelled when the contact angle increased. The area percentage of adherent bacterial cells decreased with the decrease in the contact area of a cell on ANS. This means that cell accessibility on ANS depends on the contact area. This research reveals the effectiveness of the nanopored structures in repelling cells. PMID:25944966

  12. Bacteria repelling on highly-ordered alumina-nanopore structures

    NASA Astrophysics Data System (ADS)

    Kim, Sunghan; Zhou, Yan; Cirillo, Jeffrey D.; Polycarpou, Andreas A.; Liang, Hong

    2015-04-01

    Bacteria introduce diseases and infections to humans by their adherence to biomaterials, such as implants and surgical tools. Cell desorption is an effective step to reduce such damage. Here, we report mechanisms of bacteria desorption. An alumina nanopore structure (ANS) with pore size of 35 nm, 55 nm, 70 nm, and 80 nm was used as substrate to grow Escherichia coli (E. coli) cells. A bacteria repelling experimental method was developed to quantitatively evaluate the area percentage of adherent bacterial cells that represent the nature of cell adhesion as well as desorption. Results showed that there were two crucial parameters: contact angle and contact area that affect the adhesion/desorption. The cells were found to be more easily repelled when the contact angle increased. The area percentage of adherent bacterial cells decreased with the decrease in the contact area of a cell on ANS. This means that cell accessibility on ANS depends on the contact area. This research reveals the effectiveness of the nanopored structures in repelling cells.

  13. Probing Water Structures in Nanopores Using Tunneling Currents

    NASA Astrophysics Data System (ADS)

    Boynton, P.; Di Ventra, M.

    2013-11-01

    We study the effect of volumetric constraints on the structure and electronic transport properties of distilled water in a nanopore with embedded electrodes. Combining classical molecular dynamics simulations with quantum scattering theory, we show that the structural motifs water exhibits inside the pore can be probed directly by tunneling. In particular, we show that the current does not follow a simple exponential curve at a critical pore diameter of about 8 Å, rather it is larger than the one expected from simple tunneling through a barrier. This is due to a structural transition from bulklike to “nanodroplet” water domains. Our results can be tested with present experimental capabilities to develop our understanding of water as a complex medium at nanometer length scales.

  14. Structural Characterization of Nanoporous Pmssq Thin Films

    NASA Astrophysics Data System (ADS)

    Briber, R. M.; Yang, G. Y.; Huang, E.; Kim, H. C.; Rice, P. M.; Volksen, W.; Miller, R. D.; Shin, K.

    2002-03-01

    The semiconductor industry roadmap requires the next generation of interlayer dielectric materials to have a dielectric constant k below 2.0 and thermal stability to 500 ^oC. Porous Dielectrics are an attractive route to obtain such materials. One potential system is polymethylsilsesquioxane (PMSSQ) with nanometer sized pores templated by the incorporation of a thermally degradable polymer. Film were prepared by dissolving the matrix precursor materials (MSSQ oligomer mixture) and porogen (PMMA-co-DMAEMA) as a template for creating the pores in a common solvent (propylene glycol methyl ether) and spin casting onto a silicon single crystal substrate. The film is subjected to an initial heat treatment in nitrogen at 225^oC to cure the matrix (i.e. polymerize and cross-link) and then a second heat treatment to 375 450^oC to degrade the porogen to form the pores. The pore evolution and characterization are performed using small angle neutron scattering (SANS), transmission electron microscopy (TEM) and neutron reflectivity (NR). In-situ SANS experiments revealed that the pores evolution follows a process of phase separation and burnout of the porogen copolymer. TEM observation shows that pore size, morphology and spatial distribution depend on the concentration of porogen in the original hybrid material. Average pore size increases as a function of porogen concentration. Porous morphology changes from isolated pores at low porogen concentration (<10 wt. %) to fully interconnected pores at higher porogen concentration (>40 wt. %). Percolation threshold is located at 30 wt. % porogen content. Neutron reflectivity is used to study the pore structure and distribution normal to the film thickness.

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

    PubMed Central

    Bhattacharya, Jaydeep; Kisner, Alexandre; Offenhäusser, Andreas

    2011-01-01

    Summary 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. PMID:21977420

  16. Enhanced structural stability of nanoporous zirconia under irradiation of He

    SciTech Connect

    Yang, Tengfei; Huang, Xuejun; Wang, Chenxu; Zhang, Yanwen; Xue, Jianming; Yan, Sha; Wang, Yuguang

    2012-01-01

    This work reports a greatly enhanced tolerance for He irradiation-induced swelling in nanocrystalline zirconia film with interconnected nanoporous structure (hereinafter referred as to NC-C). Compared to bulk yttria-stabilized zirconia (YSZ) and another nanocrystalline zirconia film only with discrete nano voids (hereinafter referred as to NC-V), the NC-C film reveals good tolerance for irradiation of high-fluence He. No appreciable surface blistering can be found even at the highest fluence of 6 1017 cm2 in NCC film. From TEM analysis of as-irradiated samples, the enhanced tolerance for volume swelling in NCC film is attributed to the enhanced diffusion mechanism of deposited He via widely distributed nano channels. Furthermore, the growth of grain size is quite small for both nanocrystalline zirconia films after irradiation, which is ascribed to the decreasing of area of grain boundary due to loose structure and low energy of primary knock-on atoms for He ions.

  17. Hierarchical structural nanopore arrays fabricated by pre-patterning aluminum using nanosphere lithography.

    PubMed

    Wang, Xinnan; Xu, Shuping; Cong, Ming; Li, Haibo; Gu, Yuejiao; Xu, Weiqing

    2012-04-10

    A highly ordered and hierarchical structural nanopore array is fabricated via anodizing a pre-patterned aluminum foil under an optimized voltage. A pre-patterned hexagonal nanoindentation array on an aluminum substrate is prepared via the nanosphere lithography method. This pattern leads to an elaborate nanochannel structure with seven nanopores in each nanoindentation after anodization treatment. The structure achieved in our study is new, interesting, and likely to be applied in photonic devices. PMID:22315204

  18. Ultrasensitive food toxin biosensor using frequency based signals of silicon oxide nanoporous structure

    NASA Astrophysics Data System (ADS)

    Ghosh, H.; RoyChaudhuri, C.

    2013-06-01

    We report an electrochemically fabricated silicon oxide nanoporous structure for ultrasensitive detection of AfB1 in food by shift in peak frequency corresponding to maximum sensitivity. It has been observed that the impedance sensitivity changes from 19% to 40% (which is only twice) where as the peak frequency shifts from 500 Hz to 50 kHz, for a change in concentration from 1 fg/ml to 1 pg/ml. This has been attributed to the combined effect of the significant pore narrowing with increasing AfB1 concentration and the opposing nature of impedance change within the nanopores and the conducting substrate immediately below the nanoporous layer.

  19. Obtaining structural information of small proteins using solid-state nanopores and high-bandwidth measurements

    NASA Astrophysics Data System (ADS)

    Niedzwiecki, David; Lanci, Christopher; Saven, Jeffery; Drndic, Marija

    2015-03-01

    The use of biological nanopores sensors to characterize proteins has proved a fruitful field of study. Solid-state nanopores hold several advantages over their biological counterparts, including the ability to tune pore diameter and their robustness to external conditions. Despite these advantages, the use of solid-state nanopores for protein analysis has proved difficult due to rapid translocation times of proteins and poor signal-to-noise of small peptides. Recently, improvements in high-bandwidth acquisition and in signal-to-noise have made the study of small peptides using solid-state nanopores feasible. Here we report on the detection and characterization of peptides as small as 33 amino-acids in length using sub-10 nm thin silicon nitride nanopores, giving high signal levels, combined with high-bandwidth electronics. In addition we show differentiation between monomers and dimer forms of the GCN-4 p1 leucine zipper, a coil-coil structure, and compare this with the unstructured 33-mer. The differentiation between these two forms demonstrates the possibility of extracting useful structural information from short peptide structures using modern solid-state nanopore systems.

  20. Structural Integrity of Proteins under Applied Bias during Solid-State Nanopore Translocation

    NASA Astrophysics Data System (ADS)

    Hasan, Mohammad R.; Khanzada, Raja Raheel; Mahmood, Mohammed A. I.; Ashfaq, Adnan; Iqbal, Samir M.

    2015-03-01

    The translocation behavior of proteins through solid-state nanopores can be used as a new way to detect and identify proteins. The ionic current through a nanopore that flows under applied bias gets perturbed when a biomolecule traverses the Nanopore. It is important for a protein detection scheme to know of any changes in the three-dimensional structure of the molecule during the process. Here we report the data on structural integrity of protein during translocation through nanopore under different applied biases. Nanoscale Molecular Dynamic was used to establish a framework to study the changes in protein structures as these travelled across the nanopore. The analysis revealed the contributions of structural changes of protein to its ionic current signature. As a model, thrombin protein crystalline structure was imported and positioned inside a 6 nm diameter pore in a 6 nm thick silicon nitride membrane. The protein was solvated in 1 M KCl at 295 K and the system was equilibrated for 20 ns to attain its minimum energy state. The simulation was performed at different electric fields from 0 to 1 kCal/(mol.Å.e). RMSD, radial distribution function, movement of the center of mass and velocity of the protein were calculated. The results showed linear increments in the velocity and perturbations in ionic current profile with increasing electric potential. Support Acknowledged from NSF through ECCS-1201878.

  1. Etching anisotropy mechanisms lead to morphology-controlled silicon nanoporous structures by metal assisted chemical etching.

    PubMed

    Jiang, Bing; Li, Meicheng; Liang, Yu; Bai, Yang; Song, Dandan; Li, Yingfeng; Luo, Jian

    2016-02-01

    The etching anisotropy induced by the morphology and rotation of silver particles controls the morphology of silicon nanoporous structures, through various underlying complex etching mechanisms. The level of etching anisotropy can be modulated by controlling the morphology of the silver catalyst to obtain silicon nanoporous structures with straight pores, cone-shaped pores and pyramid-shaped pores. In addition, the structures with helical pores are obtained by taking advantage of the special anisotropic etching, which is induced by the rotation and revolution of silver particles during the etching process. An investigation of the etching anisotropy during metal assisted chemical etching will promote a deep understanding of the chemical etching mechanism of silicon, and provide a feasible approach to fabricate Si nanoporous structures with special morphologies. PMID:26785718

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

    NASA Astrophysics Data System (ADS)

    Huber, Patrick

    2015-03-01

    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.

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

    PubMed

    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. PMID:25679044

  4. Fabrication of complete titania nanoporous structures via electrochemical anodization of Ti

    PubMed Central

    2011-01-01

    We present a novel method to fabricate complete and highly oriented anodic titanium oxide (ATO) nano-porous structures with uniform and parallel nanochannels. ATO nano-porous structures are fabricated by anodizing a Ti-foil in two different organic viscous electrolytes at room temperature using a two-step anodizing method. TiO2 nanotubes covered with a few nanometer thin nano-porous layer is produced when the first and the second anodization are carried out in the same electrolyte. However, a complete titania nano-porous (TNP) structures are obtained when the second anodization is conducted in a viscous electrolyte when compared to the first one. TNP structure was attributed to the suppression of F-rich layer dissolution between the cell boundaries in the viscous electrolyte. The structural morphologies were examined by field emission scanning electron microscope. The average pore diameter is approximately 70 nm, while the average inter-pore distance is approximately 130 nm. These TNP structures are useful to fabricate other nanostructure materials and nanodevices. PMID:21711844

  5. Fabrication of complete titania nanoporous structures via electrochemical anodization of Ti.

    PubMed

    Ali, Ghafar; Chen, Chong; Yoo, Seung Hwa; Kum, Jong Min; Cho, Sung Oh

    2011-01-01

    We present a novel method to fabricate complete and highly oriented anodic titanium oxide (ATO) nano-porous structures with uniform and parallel nanochannels. ATO nano-porous structures are fabricated by anodizing a Ti-foil in two different organic viscous electrolytes at room temperature using a two-step anodizing method. TiO2 nanotubes covered with a few nanometer thin nano-porous layer is produced when the first and the second anodization are carried out in the same electrolyte. However, a complete titania nano-porous (TNP) structures are obtained when the second anodization is conducted in a viscous electrolyte when compared to the first one. TNP structure was attributed to the suppression of F-rich layer dissolution between the cell boundaries in the viscous electrolyte. The structural morphologies were examined by field emission scanning electron microscope. The average pore diameter is approximately 70 nm, while the average inter-pore distance is approximately 130 nm. These TNP structures are useful to fabricate other nanostructure materials and nanodevices. PMID:21711844

  6. Fabrication of complete titania nanoporous structures via electrochemical anodization of Ti

    NASA Astrophysics Data System (ADS)

    Ali, Ghafar; Chen, Chong; Yoo, Seung Hwa; Kum, Jong Min; Cho, Sung Oh

    2011-12-01

    We present a novel method to fabricate complete and highly oriented anodic titanium oxide (ATO) nano-porous structures with uniform and parallel nanochannels. ATO nano-porous structures are fabricated by anodizing a Ti-foil in two different organic viscous electrolytes at room temperature using a two-step anodizing method. TiO2 nanotubes covered with a few nanometer thin nano-porous layer is produced when the first and the second anodization are carried out in the same electrolyte. However, a complete titania nano-porous (TNP) structures are obtained when the second anodization is conducted in a viscous electrolyte when compared to the first one. TNP structure was attributed to the suppression of F-rich layer dissolution between the cell boundaries in the viscous electrolyte. The structural morphologies were examined by field emission scanning electron microscope. The average pore diameter is approximately 70 nm, while the average inter-pore distance is approximately 130 nm. These TNP structures are useful to fabricate other nanostructure materials and nanodevices.

  7. The influence of aluminum grain size on alumina nanoporous structure

    SciTech Connect

    Feil, A. F.; Costa, M. V. da; Amaral, L.; Teixeira, S. R.; Migowski, P.; Dupont, J.; Machado, G.; Peripolli, S. B.

    2010-01-15

    An approach to control the interpore distances and nanopore diameters of 150-nm-thick thin aluminum films is reported here. The Al thin films were grown by sputtering on p-type silicon substrate and anodized with a conventional anodization process in a phosphoric acid solution. It was found that interpore distance and pore diameter are related to the aluminum grain size and can be controlled by annealing. The grain contours limit the sizes of alumina cells. This mechanism is valid for grain sizes supporting only one alumina cell and consequently only one pore.

  8. Sensitive Zn(2+) sensor based on biofunctionalized nanopores via combination of DNAzyme and DNA supersandwich structures.

    PubMed

    Liu, Nannan; Hou, Ruizuo; Gao, Pengcheng; Lou, Xiaoding; Xia, Fan

    2016-06-21

    The sensitivity of detection based on biofunctionalized nanopores is limited since the target-to-signal ratio is 1 : 1. Isothermal amplification is a promising amplification strategy at constant temperature due to its easy operation, quick results, PCR-like sensitivity, low cost and energy efficiency. In the present work, the isothermally amplified detection of Zn(2+) is achieved by using a DNA supersandwich structure and Zn(2+)-requiring DNAzymes. The DNA supersandwich structures, due to the multiple amplification of nucleic acids, heavily plug the nanopore. Simultaneously, the DNA supersandwich structures bond with the sessile probe (SP) of the substrate in the nanopore which partially hybridizes with DNAzymes. In the presence of Zn(2+), the Zn(2+)-requiring DNAzyme cleaves the SP into two fragments, while the DNA supersandwich structures are peeled off and the ionic pathway is unimpeded. A steep drop and a sequential complete recovery of the current occur in the I-V plot when the DNA supersandwich structures are decorated and peeled off. In the present system, the reliable detection limit of Zn(2+) is as low as 1 nM. Discrimination between different types of ions (Cu(2+), Hg(2+), Pb(2+)) is achieved. PMID:26911926

  9. Quantitative Analysis of the Nanopore Translocation Dynamics of Simple Structured Polynucleotides

    PubMed Central

    Schink, Severin; Renner, Stephan; Alim, Karen; Arnaut, Vera; Simmel, Friedrich C.; Gerland, Ulrich

    2012-01-01

    Nanopore translocation experiments are increasingly applied to probe the secondary structures of RNA and DNA molecules. Here, we report two vital steps toward establishing nanopore translocation as a tool for the systematic and quantitative analysis of polynucleotide folding: 1), Using α-hemolysin pores and a diverse set of different DNA hairpins, we demonstrate that backward nanopore force spectroscopy is particularly well suited for quantitative analysis. In contrast to forward translocation from the vestibule side of the pore, backward translocation times do not appear to be significantly affected by pore-DNA interactions. 2), We develop and verify experimentally a versatile mesoscopic theoretical framework for the quantitative analysis of translocation experiments with structured polynucleotides. The underlying model is based on sequence-dependent free energy landscapes constructed using the known thermodynamic parameters for polynucleotide basepairing. This approach limits the adjustable parameters to a small set of sequence-independent parameters. After parameter calibration, the theoretical model predicts the translocation dynamics of new sequences. These predictions can be leveraged to generate a baseline expectation even for more complicated structures where the assumptions underlying the one-dimensional free energy landscape may no longer be satisfied. Taken together, backward translocation through α-hemolysin pores combined with mesoscopic theoretical modeling is a promising approach for label-free single-molecule analysis of DNA and RNA folding. PMID:22225801

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

    NASA Astrophysics Data System (ADS)

    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. MinION nanopore sequencing identifies the position and structure of a bacterial antibiotic resistance island.

    PubMed

    Ashton, Philip M; Nair, Satheesh; Dallman, Tim; Rubino, Salvatore; Rabsch, Wolfgang; Mwaigwisya, Solomon; Wain, John; O'Grady, Justin

    2015-03-01

    Short-read, high-throughput sequencing technology cannot identify the chromosomal position of repetitive insertion sequences that typically flank horizontally acquired genes such as bacterial virulence genes and antibiotic resistance genes. The MinION nanopore sequencer can produce long sequencing reads on a device similar in size to a USB memory stick. Here we apply a MinION sequencer to resolve the structure and chromosomal insertion site of a composite antibiotic resistance island in Salmonella Typhi Haplotype 58. Nanopore sequencing data from a single 18-h run was used to create a scaffold for an assembly generated from short-read Illumina data. Our results demonstrate the potential of the MinION device in clinical laboratories to fully characterize the epidemic spread of bacterial pathogens. PMID:25485618

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

    PubMed

    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. PMID:23981676

  13. Structural Engineering of Nanoporous Anodic Alumina Photonic Crystals by Sawtooth-like Pulse Anodization.

    PubMed

    Law, Cheryl Suwen; Santos, Abel; Nemati, Mahdieh; Losic, Dusan

    2016-06-01

    This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization amplitude, number of anodization pulses, ramp ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism. PMID:27171214

  14. Correlation of the structure and applications of dealloyed nanoporous metals in catalysis and energy conversion/storage

    NASA Astrophysics Data System (ADS)

    Qiu, H.-J.; Xu, Hai-Tao; Liu, Li; Wang, Yu

    2014-12-01

    Nanoporous metals produced by dealloying have shown great promise in many areas such as catalysis/electrocatalysis, energy conversion/storage, sensing/biosensing, actuation, and surface-enhanced Raman scattering. Particularly, nanoscale metal ligaments with high electronic conductivity, tunable size and rich surface chemistry make nanoporous metals very promising as catalysts/electrocatalysts for energy conversion applications such as fuel cells and also as versatile three-dimensional substrates for energy-storage in supercapacitors and lithium ion batteries. In this review, we focus on the recent developments of dealloyed nanoporous metals in both catalysis/electrocatalysis and energy storage. In particular, based on the state-of-the-art electron microscopy characterization, we explain the atomic origin of the high catalytic activity of nanoporous gold. We also highlight the recent advances in rationally designing nanoporous metal-based composites and hierarchical structures for enhanced energy storage. Finally, we conclude with some outlook and perspectives with respect to future research on dealloyed nanoporous metals in catalysis- and energy-related applications.

  15. Structure and dynamics of a Gay-Berne liquid crystal confined in cylindrical nanopores.

    PubMed

    Ji, Qing; Lefort, Ronan; Busselez, Rémi; Morineau, Denis

    2009-06-21

    Gay-Berne liquid crystals confined in two cylindrical nanopores with different pore sizes were studied by molecular dynamics simulation. Their structure and dynamics properties were obtained and compared with those of the bulk. Our data show that confinement changes the bulk isotropic-to-nematic transition to a continuous ordering from a paranematic to a nematic phase. Moreover, confinement strongly hinders the smectic translational order. The molecular dynamics is characterized by the translational diffusion coefficients and the first-rank reorientational correlation times. Very different characteristic times and temperature variations in the dynamics are observed in confinement. Spatially resolved quantities illustrate that confinement induces predominant structural and dynamical heterogeneities. PMID:19548733

  16. Structure and dynamics of a Gay-Berne liquid crystal confined in cylindrical nanopores

    NASA Astrophysics Data System (ADS)

    Ji, Qing; Lefort, Ronan; Busselez, Rémi; Morineau, Denis

    2009-06-01

    Gay-Berne liquid crystals confined in two cylindrical nanopores with different pore sizes were studied by molecular dynamics simulation. Their structure and dynamics properties were obtained and compared with those of the bulk. Our data show that confinement changes the bulk isotropic-to-nematic transition to a continuous ordering from a paranematic to a nematic phase. Moreover, confinement strongly hinders the smectic translational order. The molecular dynamics is characterized by the translational diffusion coefficients and the first-rank reorientational correlation times. Very different characteristic times and temperature variations in the dynamics are observed in confinement. Spatially resolved quantities illustrate that confinement induces predominant structural and dynamical heterogeneities.

  17. Fabrication of nanoporous Cu-Pt(Pd) core/shell structure by galvanic replacement and its application in electrocatalysis.

    PubMed

    Xu, Caixia; Liu, Yunqing; Wang, Jinping; Geng, Haoran; Qiu, Huajun

    2011-12-01

    We describe a general strategy to fabricate a new type of nanoporous core/shell structured bimetallic nanocomposites with controllable metal components. Nanoporous copper (NPC) obtained by dealloying Cu/Al alloy is used as both reducing agent and three-dimensional substrate. Electron microscope and X-ray diffraction characterizations demonstrated that a simply galvanic-replacement reaction with H(2)PtCl(6) aqueous solution can easily generate nanoporous core/shell structure with a thin Pt/Cu alloy shell and Cu (or Pt/Cu alloy) core. The morphology and crystal structure evolution of the nanocomposites are studied and discussed in detail. The as-prepared bimetallic PtCu nanocomposites show greatly enhanced catalytic activity and stability toward methanol electro-oxidation as compared with commercial Pt/C catalyst. This facile in situ preparation strategy is also suitable for large-scale production of this novel and inexpensive catalyst. PMID:22034948

  18. Structure and hydrogen adsorption properties in low density nanoporous carbons from simulations

    SciTech Connect

    Peng, L.; Morris, James R

    2012-01-01

    We systematically model the hydrogen adsorption in nanoporous carbons over a wide range of carbon bulk densities (0.6 - 2.4 g/cm3) by using tight binding molecular dynamics simulations for the carbon structures and thermodynamics calculations of the hydrogen adsorption. The resulting structures are in good agreement with the experimental data of ultra-microporous carbon (UMC), a wood-based activated carbon, as indicated by comparisons of the microstructure at atomic level, pair distribution function, and pore size distribution. The hydrogen adsorption calculations in carbon structures demonstrate both a promising hydrogen storage capacity (excess uptake of 1.33 wt% at 298K and 5 MPa, for carbon structures at the lower range of densities) and a reasonable heat of adsorption (12-22 kJ/mol). This work demonstrates that increasing the heat of adsorption does not necessarily increase the hydrogen uptake. In fact, the available adsorption volume is as important as the isosteric heat of adsorption for hydrogen storage in nanoporous carbons.

  19. Geochemical significance of alkylbenzene distributions in flash pyrolysates of kerogens, coals, and asphaltenes

    NASA Astrophysics Data System (ADS)

    Hartgers, Walter A.; Damsté, Jaap S. Sinninghe; de Leeuw, Jan W.

    1994-04-01

    The distribution of C 0-C 5 alkylbenzenes in flash pyrolysates of forty-seven immature kerogens and coals from different geographical locations and of different ages were studied using gas chromatography (GC) in combination with mass spectrometry (MS) in order to decipher the origin of aromatic moieties in macromolecular matter. All possible structural isomers of the alkylated benzenes were determined, and, in some cases, absolute yields were calculated. Sulphur-rich (Type II-S) kerogens yield higher absolute amounts of alkylbenzenes in comparison to Type I, II, and III kerogens. The variations in internal distribution patterns of C 2-C 4 alkylbenzenes were analyzed using multivariate analysis techniques (principal component analysis; PCA). Major variations in alkylbenzene distributions were due to an increased abundance of specific alkylbenzenes, which are related to specific precursor moieties in the macromolecular structure assuming that they are mainly formed via β-cleavage. Alkylbenzenes possessing "linear" carbon skeletons are enhanced in flash pyrolysates of Guttenberg and Estonian Kukersite kerogens (Type I) and are proposed to be derived from linear precursors which have undergone cyclization/aromatization. Relatively high amounts of 1,2,3,4- and 1,2,3,5-tetramethylbenzenes were found in flash pyrolysates of Womble and Duvernay kerogens (Type II) which are likely to be derived from macromolecularly bound diaromatic carotenoids. The relatively high abundance of 1,2,3-trimethylbenzene and 1,3-/1,4-dimethylbenzene in pyrolysates of Monterey kerogens (Type II-S) is proposed to be indicative of the presence of bound nonaromatic carotenoids (e.g., β,β-carotene) which have undergone aromatization and/or loss of methyl groups upon diagenesis. 1-methyl-4-isopropylbenzene, which appears in relatively high amounts in flash pyrolysates of Walcott Chuar kerogen (Type II) and Catalan coals (Type III), is thought to be derived from a heteroatom-bound precursor. These

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

    PubMed Central

    Kumeria, Tushar; Santos, Abel; Losic, Dusan

    2014-01-01

    Electrochemical anodization of pure aluminum enables the growth of highly ordered nanoporous anodic alumina (NAA) structures. This has made NAA one of the most popular nanomaterials with applications including molecular separation, catalysis, photonics, optoelectronics, sensing, drug delivery, and template synthesis. Over the past decades, the ability to engineer the structure and surface chemistry of NAA and its optical properties has led to the establishment of distinctive photonic structures that can be explored for developing low-cost, portable, rapid-response and highly sensitive sensing devices in combination with surface plasmon resonance (SPR) and reflective interference spectroscopy (RIfS) techniques. This review article highlights the recent advances on fabrication, surface modification and structural engineering of NAA and its application and performance as a platform for SPR- and RIfS-based sensing and biosensing devices. PMID:25004150

  1. Omnidirectional excitation of sidewall gap-plasmons in a hybrid gold-nanoparticle/aluminum-nanopore structure

    NASA Astrophysics Data System (ADS)

    Lumdee, Chatdanai; Kik, Pieter G.

    2016-06-01

    The gap-plasmon resonance of a gold nanoparticle inside a nanopore in an aluminum film is investigated in polarization dependent single particle microscopy and spectroscopy. Scattering and transmission measurements reveal that gap-plasmons of this structure can be excited and observed under normal incidence excitation and collection, in contrast to the more common particle-on-a-mirror structure. Correlation of numerical simulations with optical spectroscopy suggests that a local electric field enhancement factor in excess of 50 is achieved under normal incidence excitation, with a hot-spot located near the top surface of the structure. It is shown that the strong field enhancement from this sidewall gap-plasmon mode can be efficiently excited over a broad angular range. The presented plasmonic structure lends itself to implementation in low-cost, chemically stable, easily addressable biochemical sensor arrays providing large optical field enhancement factors.

  2. Multiple Approaches to Characterizing Nano-Pore Structure of Barnett Shale

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Gao, Z.; Ewing, R. P.; Dultz, S.; Kaufmann, J.; Hamamoto, S.; Webber, B.; Ding, M.

    2013-12-01

    Microscopic characteristics of porous media - pore shape, pore-size distribution, and pore connectivity - control fluid flow and mass transport. This presentation discusses various approaches to investigating nano-pore structure of Barnett shale, with its implications in gas production behavior. The innovative approaches include imbibition, tracer diffusion, edge-accessible porosity, porosimetry (mercury intrusion porosimetry, nitrogen and water vapor sorption isotherms, and nuclear magnetic resonance cyroporometry), and imaging (Wood's metal impregnation followed with laser ablation-inductively coupled plasma-mass spectrometry, focused ion beam/scanning electron microscopy, and small angle neutron scattering). Results show that the shale pores are predominantly in the nm size range, with measured median pore-throat diameters about 5 nm. But small pore size is not the major contributor to low gas recovery; rather, the low mass diffusivity appears to be caused by low pore connectivity of Barnett shale. Chemical diffusion in sparsely-connected pore spaces is not well described by classical Fickian behavior; anomalous behavior is suggested by percolation theory, and confirmed by results of imbibition and diffusion tests. Our evolving complementary approaches, with their several advantages and disadvantages, provide a rich toolbox for tackling the nano-pore structure characteristics of shales and other natural rocks.

  3. Formation of nanoporous structures in metallic materials by pulse-periodic laser treatment

    NASA Astrophysics Data System (ADS)

    Murzin, Serguei P.

    2015-09-01

    A method of the formation of nanoporous structures in metallic materials by pulse-periodic laser treatment was developed. In this study, the multicomponent aluminum-iron brass was considered and the nanoporous structure across the entire cross section of the material with a thickness of 50 μm was formed. The method was implemented using a CO2 laser processing unit. The pulse-periodic laser treatment of the Cu-Zn-Al-Fe alloy with pulse frequency of 5 Hz has led to the formation of nanosized cavities due to accumulation of internal stresses during cyclic heating and cooling at high speeds. It was determined that the pores of a channel type with average widths of 80-100 nm are formed in the central region of the heat-affected zone during laser action with thermocycling. When implementing the chosen conditions of the pulse-periodic laser processing, the localness in depth and area of the physical processes occurring in the heat-affected zone is ensured, while maintaining the original properties of the material and the absence of significant deformations in the rest of the volume. This patented process is perspective for the production not only catalysts for chemical reactions, but for ultrafiltration and microfiltration membranes as well.

  4. Deceleration of single-stranded DNA passing through a nanopore using a nanometre-sized bead structure

    NASA Astrophysics Data System (ADS)

    Goto, Yusuke; Haga, Takanobu; Yanagi, Itaru; Yokoi, Takahide; Takeda, Ken-Ichi

    2015-11-01

    DNA sequencing with a solid-state nanopore requires a reduction of the translocation speeds of single-stranded DNA (ssDNA) over 10 μs/base. In this study, we report that a nanometre-sized bead structure constructed around a nanopore can reduce the moving speed of ssDNA to 270 μs/base by adjusting the diameter of the bead and its surface chemical group. This decelerating effect originates from the strong interaction between ssDNA and the chemical group on the surface of the bead. This nanostructure was simply prepared by dip coating in which a substrate with a nanopore was immersed in a silica bead solution and then dried in an oven. As compared with conventional approaches, our novel method is less laborious, simpler to perform and more effective in reducing ssDNA translocation speed.

  5. Deceleration of single-stranded DNA passing through a nanopore using a nanometre-sized bead structure

    PubMed Central

    Goto, Yusuke; Haga, Takanobu; Yanagi, Itaru; Yokoi, Takahide; Takeda, Ken-ichi

    2015-01-01

    DNA sequencing with a solid-state nanopore requires a reduction of the translocation speeds of single-stranded DNA (ssDNA) over 10 μs/base. In this study, we report that a nanometre-sized bead structure constructed around a nanopore can reduce the moving speed of ssDNA to 270 μs/base by adjusting the diameter of the bead and its surface chemical group. This decelerating effect originates from the strong interaction between ssDNA and the chemical group on the surface of the bead. This nanostructure was simply prepared by dip coating in which a substrate with a nanopore was immersed in a silica bead solution and then dried in an oven. As compared with conventional approaches, our novel method is less laborious, simpler to perform and more effective in reducing ssDNA translocation speed. PMID:26559466

  6. Structural evolution of nanoporous ultra-low k dielectrics under voltage stress

    NASA Astrophysics Data System (ADS)

    Raja, Archana; Shaw, Thomas; Grill, Alfred; Laibowitz, Robert; Heinz, Tony

    2013-03-01

    High speed interconnects in advanced integrated circuits require ultra-low-k dielectrics. Reduction of the dielectric constant is achieved via incorporation of nanopores in structures containing silicon, carbon, oxygen and hydrogen (SiCOH). We study nanoporous SiCOH films of k=2.5 and thicknesses of 40 - 400 nm. Leakage currents develop in the films under long-term voltage stress, eventually leading to breakdown and chip failure. Previous work* has shown the build-up of trap states as dielectric breakdown progresses. Using FTIR spectroscopy we have tracked the reorganization of the bonds in the SiCOH networks induced by voltage stress. Our results indicate that the cleavage of the Si-C and SiC-O bonds contribute toward increase in the density of bulk trapping states as breakdown is approached. AC conductance and capacitance measurements have also been carried out to describe interfacial and bulk traps and mechanisms. Comparison of breakdown properties of films with differing carbon content will also be presented to further delineate the role of carbon. *Atkin, J.M.; Shaw, T.M.; Liniger, E.; Laibowitz, R.B.; Heinz, T.F. Reliability Physics Symposium (IRPS), 2012 IEEE International Supported by the Semiconductor Research Corporation

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

    SciTech Connect

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

    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.

  8. Revealing Correlation of Valence State with Nanoporous Structure in Cobalt Catalyst Nanoparticles by In situ Environmental TEM

    SciTech Connect

    Xin H. L.; Diaz R.; Pach, E.A.; Stach, E.A.; Salmeron, M.; Zheng, H.

    2012-05-01

    Simultaneously probing the electronic structure and morphology of materials at the nanometer or atomic scale while a chemical reaction proceeds is significant for understanding the underlying reaction mechanisms and optimizing a materials design. This is especially important in the study of nanoparticle catalysts, yet such experiments have rarely been achieved. Utilizing an environmental transmission electron microscope equipped with a differentially pumped gas cell, we are able to conduct nanoscopic imaging and electron energy loss spectroscopy in situ for cobalt catalysts under reaction conditions. Studies reveal quantitative correlation of the cobalt valence states with the particles' nanoporous structures. The in situ experiments were performed on nanoporous cobalt particles coated with silica, while a 15 mTorr hydrogen environment was maintained at various temperatures (300-600 C). When the nanoporous particles were reduced, the valence state changed from cobalt oxide to metallic cobalt and concurrent structural coarsening was observed. In situ mapping of the valence state and the corresponding nanoporous structures allows quantitative analysis necessary for understanding and improving the mass activity and lifetime of cobalt-based catalysts, for example, for Fischer-Tropsch synthesis that converts carbon monoxide and hydrogen into fuels, and uncovering the catalyst optimization mechanisms.

  9. Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids

    PubMed Central

    2012-01-01

    We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.) PMID:22515214

  10. On the importance of a precise crystal structure for simulating gas adsorption in nanoporous materials.

    PubMed

    Lawler, Keith V; Hulvey, Zeric; Forster, Paul M

    2015-07-15

    We show that simulation of gas adsorption in nanoporous sorbents may be highly sensitive to accurate crystallographic coordinates, even for frameworks anticipated to have low flexibility. PMID:26133672

  11. Transition-Metal Doped Ceria Microspheres with Nanoporous Structures for CO Oxidation.

    PubMed

    Zhou, Lin; Li, Xiaoxiao; Yao, Ze; Chen, Zhuwen; Hong, Mei; Zhu, Rongshu; Liang, Yongye; Zhao, Jing

    2016-01-01

    Catalytic oxidation of carbon monoxide (CO) is of great importance in many different fields of industry. Until now it still remains challenging to use non-noble metal based catalysts to oxidize CO at low temperature. Herein, we report a new class of nanoporous, uniform, and transition metal-doped cerium (IV) oxide (ceria, CeO2) microsphere for CO oxidation catalysis. The porous and uniform microsphere is generated by sacrificed polymer template. Transition-metals, like Cu, Co, Ni, Mn and Fe, were doped into CeO2 microspheres. The combination of hierarchical structure and metal doping afford superior catalytic activities of the doped ceria microspheres, which could pave a new way to advanced non-precious metal based catalysts for CO oxidation. PMID:27030159

  12. Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance.

    PubMed

    Li, Yuanyuan; Fu, Qiliang; Yu, Shun; Yan, Min; Berglund, Lars

    2016-04-11

    Optically transparent wood (TW) with transmittance as high as 85% and haze of 71% was obtained using a delignified nanoporous wood template. The template was prepared by removing the light-absorbing lignin component, creating nanoporosity in the wood cell wall. Transparent wood was prepared by successful impregnation of lumen and the nanoscale cellulose fiber network in the cell wall with refractive-index-matched prepolymerized methyl methacrylate (MMA). During the process, the hierarchical wood structure was preserved. Optical properties of TW are tunable by changing the cellulose volume fraction. The synergy between wood and PMMA was observed for mechanical properties. Lightweight and strong transparent wood is a potential candidate for lightweight low-cost, light-transmitting buildings and transparent solar cell windows. PMID:26942562

  13. Transition-Metal Doped Ceria Microspheres with Nanoporous Structures for CO Oxidation

    NASA Astrophysics Data System (ADS)

    Zhou, Lin; Li, Xiaoxiao; Yao, Ze; Chen, Zhuwen; Hong, Mei; Zhu, Rongshu; Liang, Yongye; Zhao, Jing

    2016-03-01

    Catalytic oxidation of carbon monoxide (CO) is of great importance in many different fields of industry. Until now it still remains challenging to use non-noble metal based catalysts to oxidize CO at low temperature. Herein, we report a new class of nanoporous, uniform, and transition metal-doped cerium (IV) oxide (ceria, CeO2) microsphere for CO oxidation catalysis. The porous and uniform microsphere is generated by sacrificed polymer template. Transition-metals, like Cu, Co, Ni, Mn and Fe, were doped into CeO2 microspheres. The combination of hierarchical structure and metal doping afford superior catalytic activities of the doped ceria microspheres, which could pave a new way to advanced non-precious metal based catalysts for CO oxidation.

  14. Transition-Metal Doped Ceria Microspheres with Nanoporous Structures for CO Oxidation

    PubMed Central

    Zhou, Lin; Li, Xiaoxiao; Yao, Ze; Chen, Zhuwen; Hong, Mei; Zhu, Rongshu; Liang, Yongye; Zhao, Jing

    2016-01-01

    Catalytic oxidation of carbon monoxide (CO) is of great importance in many different fields of industry. Until now it still remains challenging to use non-noble metal based catalysts to oxidize CO at low temperature. Herein, we report a new class of nanoporous, uniform, and transition metal-doped cerium (IV) oxide (ceria, CeO2) microsphere for CO oxidation catalysis. The porous and uniform microsphere is generated by sacrificed polymer template. Transition-metals, like Cu, Co, Ni, Mn and Fe, were doped into CeO2 microspheres. The combination of hierarchical structure and metal doping afford superior catalytic activities of the doped ceria microspheres, which could pave a new way to advanced non-precious metal based catalysts for CO oxidation. PMID:27030159

  15. A FIB-nanotomography method for accurate 3D reconstruction of open nanoporous structures.

    PubMed

    Mangipudi, K R; Radisch, V; Holzer, L; Volkert, C A

    2016-04-01

    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. PMID:26906523

  16. Nanoporous Gyroid-Structured Epoxy from Block Copolymer Templates for High Protein Adsorbability.

    PubMed

    Wang, Xin-Bo; Lin, Tze-Chung; Hsueh, Han-Yu; Lin, Shih-Chieh; He, Xiao-Dong; Ho, Rong-Ming

    2016-06-28

    Nanoporous epoxy with gyroid texture is fabricated by using a nanoporous polymer with gyroid-forming nanochannels as a template for polymerization of epoxy. The nanoporous polymer template is obtained from the self-assembly of degradable block copolymer, polystyrene-b-poly(l-lactide) (PS-PLLA), followed by hydrolysis of PLLA blocks. Templated polymerization can be conducted under ambient conditions to create well-defined, bicontinuous epoxy networks in a PS matrix. By taking advantage of multistep curing of epoxy, well-ordered robust nanoporous epoxy can be obtained after removal of PS template, giving robust porous materials. The through-hole nanoporous epoxy in the film state can be used as a coated layer to enhance the adsorbability for both lysozyme and bovine serum albumin. PMID:27245380

  17. Molecular simulation of structure and diffusion at smectite-water interfaces: Using expanded clay interlayers as model nanopores

    SciTech Connect

    Greathouse, Jeffery A.; Hart, David; Bowers, Geoffrey M.; Kirkpatrick, R. James; Cygan, Randall Timothy

    2015-07-20

    In geologic settings relevant to a number of extraction and potential sequestration processes, nanopores bounded by clay mineral surfaces play a critical role in the transport of aqueous species. Solution structure and dynamics at clay–water interfaces are quite different from their bulk values, and the spatial extent of this disruption remains a topic of current interest. We have used molecular dynamics simulations to investigate the structure and diffusion of aqueous solutions in clay nanopores approximately 6 nm thick, comparing the effect of clay composition with model Na-hectorite and Na-montmorillonite surfaces. In addition to structural properties at the interface, water and ion diffusion coefficients were calculated within each aqueous layer at the interface, as well as in the central bulk-like region of the nanopore. The results show similar solution structure and diffusion properties at each surface, with subtle differences in sodium adsorption complexes and water structure in the first adsorbed layer due to different arrangements of layer hydroxyl groups in the two clay models. Interestingly, the extent of surface disruption on bulk-like solution structure and diffusion extends to only a few water layers. Additionally, a comparison of sodium ion residence times confirms similar behavior of inner-sphere and outer-sphere surface complexes at each clay surface, but ~1% of sodium ions adsorb in ditrigonal cavities on the hectorite surface. Thus, the presence of these anhydrous ions is consistent with highly immobile anhydrous ions seen in previous nuclear magnetic resonance spectroscopic measurements of hectorite pastes.

  18. Design and fabrication of a 3D-structured gold film with nanopores for local electric field enhancement in the pore

    NASA Astrophysics Data System (ADS)

    Grant-Jacob, James A.; Zin Oo, Swe; Carpignano, Francesca; Boden, Stuart A.; Brocklesby, William S.; Charlton, Martin D. B.; Melvin, Tracy

    2016-02-01

    Three-dimensionally structured gold membrane films with nanopores of defined, periodic geometries are designed and fabricated to provide the spatially localised enhancement of electric fields by manipulation of the plasmons inside nanopores. Square nanopores of different size and orientation relative to the pyramid are considered for films in aqueous and air environments, which allow for control of the position of electric fields within the structure. Designs suitable for use with 780 nm light were created. Here, periodic pyramidal cavities produced by potassium hydroxide etching to the {111} planes of (100) silicon substrates are used as templates for creating a periodic, pyramidal structured, free-standing thin gold film. Consistent with the findings from the theoretical studies, a nano-sized hole of 50 nm square was milled through the gold film at a specific location in the cavity to provide electric field control which can subsequently used for enhancement of fluorescence or Raman scattering of molecules in the nanopore.

  19. Voltage-Gated Hydrophobic Nanopores

    SciTech Connect

    Lavrik, Nickolay V

    2011-01-01

    Hydrophobicity is a fundamental property that is responsible for numerous physical and biophysical aspects of molecular interactions in water. Peculiar behavior is expected for water in the vicinity of hydrophobic structures, such as nanopores. Indeed, hydrophobic nanopores can be found in two distinct states, dry and wet, even though the latter is thermodynamically unstable. Transitions between these two states are kinetically hindered in long pores but can be much faster in shorter pores. As it is demonstrated for the first time in this paper, these transitions can be induced by applying a voltage across a membrane with a single hydrophobic nanopore. Such voltage-induced gating in single nanopores can be realized in a reversible manner through electrowetting of inner walls of the nanopores. The resulting I-V curves of such artificial hydrophobic nanopores mimic biological voltage-gated channels.

  20. Tunable Porous Organic Crystals: Structural Scope and Adsorption Properties of Nanoporous Steroidal Ureas

    PubMed Central

    2013-01-01

    Previous work has shown that certain steroidal bis-(N-phenyl)ureas, derived from cholic acid, form crystals in the P61 space group with unusually wide unidimensional pores. A key feature of the nanoporous steroidal urea (NPSU) structure is that groups at either end of the steroid are directed into the channels and may in principle be altered without disturbing the crystal packing. Herein we report an expanded study of this system, which increases the structural variety of NPSUs and also examines their inclusion properties. Nineteen new NPSU crystal structures are described, to add to the six which were previously reported. The materials show wide variations in channel size, shape, and chemical nature. Minimum pore diameters vary from ∼0 up to 13.1 Å, while some of the interior surfaces are markedly corrugated. Several variants possess functional groups positioned in the channels with potential to interact with guest molecules. Inclusion studies were performed using a relatively accessible tris-(N-phenyl)urea. Solvent removal was possible without crystal degradation, and gas adsorption could be demonstrated. Organic molecules ranging from simple aromatics (e.g., aniline and chlorobenzene) to the much larger squalene (Mw = 411) could be adsorbed from the liquid state, while several dyes were taken up from solutions in ether. Some dyes gave dichroic complexes, implying alignment of the chromophores in the NPSU channels. Notably, these complexes were formed by direct adsorption rather than cocrystallization, emphasizing the unusually robust nature of these organic molecular hosts. PMID:24147834

  1. Fabrication of a high-density nano-porous structure on polyimide by using ultraviolet laser irradiation

    NASA Astrophysics Data System (ADS)

    Ma, Yong-Won; Jeong, Myung Yung; Lee, Sang-Mae; Shin, Bo Sung

    2016-03-01

    A new approach for fabricating a high-density nano-porous structure on polyimide (PI) by using a 355-nm UV laser is presented here. When PI was irradiated by using a laser, debris that had electrical conductivity was generated. Accordingly, that debris caused electrical defects in the field of electronics. Thus, many researchers have tried to focus on a clean processing without debris. However, this study focused on forming a high density of debris so as to fabricate a nano-porous structure consisting of nanofibers on the PI film. A PI film with closed pores and open pores was successfully formed by using a chemical blowing agent (azodicarbonamide, CBA) in an oven. Samples were precured at 130 °C and cured at 205 °C in sequence so that the closed pores might not coalesce in the film. When the laser irradiated the PI film with closed pores, nanofibers were generated because polyimide was not completely decomposed by photochemical ablation. Our results indicated that a film with micro-closed pores, in conjunction with a 355-nm pulsed laser, can facilitate the fabrication of a high-density nano-porous structure.

  2. Microfluidic synthesis of monodisperse nanoporous oxide particles and control of hierarchical pore structure.

    PubMed

    Carroll, Nick J; Crowder, Peter F; Pylypenko, Svitlana; Patterson, Wendy; Ratnaweera, Dilru R; Perahia, Dvora; Atanassov, Plamen; Petsev, Dimiter N

    2013-05-01

    Particles with hierarchical porosity can be formed by templating silica microparticles with a specially designed surfactant micelle/oil nanoemulsion mixture. The nanoemulsion oil droplet and micellar dimensions determine the pore size distribution: one set of pores with diameters of tens of nanometers coexisting with a second subset of pores with diameters of single nanometers. Further practical utility of these nanoporous particles requires precise tailoring of the hierarchical pore structure. In this synthesis study, the particle nanostructure is tuned by adjusting the oil, water, and surfactant mixture composition for the controlled design of nanoemulsion-templated features. We also demonstrate control of the size distribution and surface area of the smaller micelle-templated pores as a consequence of altering the hydrophobic chain length of the molecular surfactant template. Moreover, a microfluidic system is designed to process the low interfacial system for fabrication of monodisperse porous particles. The ability to direct the assembly of template nanoemulsion and micelle structures creates new opportunities to engineer hierarchically porous particles for utility as electrocatalysts for fuel cells, chromatography separations, drug delivery vehicles, and other applications. PMID:23387998

  3. Impedance spectroscopy of highly ordered nano-porous electrodes based on Au-AAO (anodic aluminum oxide) structure.

    PubMed

    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. PMID:24245278

  4. Mechanism of DNA Trapping in Nanoporous Structures during Asymmetric Pulsed-Field Electrophoresis

    NASA Astrophysics Data System (ADS)

    Zhou, Ya; Harrison, D. Jed

    2014-03-01

    DNA molecules (>100kbp) are trapped in separation sieves when high electric fields are applied in pulsed field electrophoresis, seriously limiting the speed of separation. Using crystalline particle arrays, to generate interstitial pores for molecular sieving, allows higher electric fields than in gels, (e.g 40 vs 5 V/cm), however trapping still limits the field strength. Using reverse pulses, which release DNA from being fully-stretched, allows higher fields (140 V/cm). We investigate the trapping mechanism of individual DNA molecules in ordered nanoporous structures. Two prerequisites for trapping are revealed by the dynamics of single trapped DNA, hernia formation and fully-stretched U/J shapes. Fully stretched DNA has longer unhooking times than expected by simple models. We propose a dielectrophoretic (DEP) force reduces the mobility of segments at the apex of the U or J, where field gradients are highest, based on simulations. A modified model for unhooking time is obtained after the DEP force is introduced. The new model explains the unhooking time data by predicting an infinite trapping time when the ratio of arm length differences (of the U or J) to molecule length Δx / L < β . β is a DEP parameter that is found to strongly increase with electric field. The work was supported by grant from Natural Sciences and Engineering Research Council of Canada (NSERC) and the National Institute for Nanotechnology (NINT).

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

    NASA Astrophysics Data System (ADS)

    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.

  6. In-situ synthesis of TiO2 network nanoporous structure on Ti wire substrate and its application in fiber dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Tao, Hong; Fang, Guo-jia; Ke, Wei-jun; Zeng, Wei; Wang, Jing

    2014-01-01

    In this paper, we explore a two-step treatment method to modify the Ti wires which are used as anode substrates of fiber dye sensitized solar cells (FDSSCs). A special kind of network nanoporous structure is formed on the surface of Ti wire substrates through sodium hydroxide hydrothermal reaction and titanium tetrachloride (TiCl4) assistant treatment. Nanoporous structures with different sizes are in-situ grown on the Ti wire substrates by changing the hydrothermal reaction condition. Then, TiO2 network nanoporous structures with branch-like nano-structure or 2D nanoflakes are obtained after TiCl4 treatment. The effects of these network nanoporous structures on the FDSSC performances are investigated intensively. It is found that these special network nanoporous structures between TiO2 nanoparticle active layer and Ti wire substrate are beneficial to the connection of the nanoparticle layer and fiber-shaped substrate, thus improving the electron transport rate and prolonging electron lifetime. As a result, the power conversion efficiency of this parallel assembled FDSSC increases to 4.64% from 2.56% after this two-step treatment.

  7. Molecular simulation of structure and diffusion at smectite-water interfaces: Using expanded clay interlayers as model nanopores

    DOE PAGESBeta

    Greathouse, Jeffery A.; Hart, David; Bowers, Geoffrey M.; Kirkpatrick, R. James; Cygan, Randall Timothy

    2015-07-20

    In geologic settings relevant to a number of extraction and potential sequestration processes, nanopores bounded by clay mineral surfaces play a critical role in the transport of aqueous species. Solution structure and dynamics at clay–water interfaces are quite different from their bulk values, and the spatial extent of this disruption remains a topic of current interest. We have used molecular dynamics simulations to investigate the structure and diffusion of aqueous solutions in clay nanopores approximately 6 nm thick, comparing the effect of clay composition with model Na-hectorite and Na-montmorillonite surfaces. In addition to structural properties at the interface, water andmore » ion diffusion coefficients were calculated within each aqueous layer at the interface, as well as in the central bulk-like region of the nanopore. The results show similar solution structure and diffusion properties at each surface, with subtle differences in sodium adsorption complexes and water structure in the first adsorbed layer due to different arrangements of layer hydroxyl groups in the two clay models. Interestingly, the extent of surface disruption on bulk-like solution structure and diffusion extends to only a few water layers. Additionally, a comparison of sodium ion residence times confirms similar behavior of inner-sphere and outer-sphere surface complexes at each clay surface, but ~1% of sodium ions adsorb in ditrigonal cavities on the hectorite surface. Thus, the presence of these anhydrous ions is consistent with highly immobile anhydrous ions seen in previous nuclear magnetic resonance spectroscopic measurements of hectorite pastes.« less

  8. Molecule-hugging graphene nanopores

    PubMed Central

    Garaj, Slaven; Liu, Song; Golovchenko, Jene A.; Branton, Daniel

    2013-01-01

    It has recently been recognized that solid-state nanopores in single-atomic-layer graphene membranes can be used to electronically detect and characterize single long charged polymer molecules. We have now fabricated nanopores in single-layer graphene that are closely matched to the diameter of a double-stranded DNA molecule. Ionic current signals during electrophoretically driven translocation of DNA through these nanopores were experimentally explored and theoretically modeled. Our experiments show that these nanopores have unusually high sensitivity (0.65 nA/Å) to extremely small changes in the translocating molecule’s outer diameter. Such atomically short graphene nanopores can also resolve nanoscale-spaced molecular structures along the length of a polymer, but do so with greatest sensitivity only when the pore and molecule diameters are closely matched. Modeling confirms that our most closely matched pores have an inherent resolution of ≤0.6 nm along the length of the molecule. PMID:23836648

  9. Molecule-hugging graphene nanopores.

    PubMed

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

    2013-07-23

    It has recently been recognized that solid-state nanopores in single-atomic-layer graphene membranes can be used to electronically detect and characterize single long charged polymer molecules. We have now fabricated nanopores in single-layer graphene that are closely matched to the diameter of a double-stranded DNA molecule. Ionic current signals during electrophoretically driven translocation of DNA through these nanopores were experimentally explored and theoretically modeled. Our experiments show that these nanopores have unusually high sensitivity (0.65 nA/Å) to extremely small changes in the translocating molecule's outer diameter. Such atomically short graphene nanopores can also resolve nanoscale-spaced molecular structures along the length of a polymer, but do so with greatest sensitivity only when the pore and molecule diameters are closely matched. Modeling confirms that our most closely matched pores have an inherent resolution of ≤ 0.6 nm along the length of the molecule. PMID:23836648

  10. Recent trends in nanopores for biotechnology

    PubMed Central

    Stoloff, Daniel H; Wanunu, Meni

    2016-01-01

    Nanopore technology employs a nanoscale hole in an insulating membrane to stochastically sense with high throughput individual biomolecules in solution. The generality of the nanopore detection principle and the ease of single-molecule detection suggest many potential applications of nanopores in biotechnology. Recent progress has been made with nanopore fabrication and sophistication, as well as with applications in DNA/protein mapping, biomolecular structure analysis, protein detection, and DNA sequencing. In addition, concepts for DNA sequencing devices have been suggested, and computational efforts have been made. The state of the nanopore field is maturing and given the right type of nanopore and operating conditions, nearly every application could revolutionize medicine in terms of speed, cost, and quality. In this review, we summarize progress in nanopores for biotechnological applications over the past 2–3 years. PMID:23266100

  11. Evaluation of Nanoporous Gold with Controlled Surface Structures for Laser Desorption Ionization (LDI) Analysis: Surface Area Versus LDI Signal Intensity

    NASA Astrophysics Data System (ADS)

    Jin, Jang Mi; Choi, Suhee; Kim, Young Hwan; Choi, Man Ho; Kim, Jongwon; Kim, Sunghwan

    2012-09-01

    The structural effect of a nanoporous gold (NPG) surface on the signal intensities of laser desorption ionization-mass spectrometry (LDI-MS) were investigated using NPG surfaces with controlled structures. The relationship between surface area and LDI efficiency was compared and evaluated. Comparisons between bare flat gold and NPG surfaces show that nanostructures increased LDI efficiency. We also found that the LDI signal decreased with increasing depth of nanoporous layers, thus increasing the surface area. This result agrees with a previous report (Shin J. A. et al., J. Am. Soc. Mass Spectrom. 2010, 21, 989) in which the LDI efficiency of small molecules decreased for ZnO wires with longer lengths. This observation was explained by the penetration and deposition of samples into locations inaccessible to photons because of structural screening. The LDI-MS analysis of oils with NPG surfaces (but without matrix) showed the same trend whereby the NPG with about a 200 nm depth of porous area showed the highest sensitivity. This study clearly shows that the active surface area for solution chemistry can differ from LDI-MS and that NPGs can function as a substrate for LDI oil analysis.

  12. Development of nanoporous structure in carbons by chemical activation with zinc chloride.

    PubMed

    Rajbhandari, Rinita; Shrestha, Lok Kumar; Pokharel, Bhadra Prasad; Pradhananga, Raja Ram

    2013-04-01

    Series of activated carbons (ACs) have been prepared from Lapsi (Choerospondias axillaris) seed powder (LSP) by chemical activation with zinc chloride (ZnCI2) and the effects of ZnCl2 impregnation ratio, carbonization time, and precursor sources on the structure and properties of ACs have been systematically investigated. Carbonization was carried out at 400 degrees C and the ratio of LSP and ZnCI2 was varied from LSP:ZnCl2 = 1:0.25 (AC-0.25), 1:0.50 (AC-0.50) 1:1 (AC-1), 1:2 (AC-2), and 1:4 (AC-4). The ACs were characterized by Fourier transform-infrared (FTIR) spectroscopy, Raman scattering, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Surface properties (effective surface areas, pore volumes, and pore size distributions) were studied by nitrogen adsorption-desorption measurements. The electrochemical and vapor sensing properties were investigated by cyclic voltammetry, and quartz crystal microbalance (QCM) method, respectively. All the ACs are amorphous materials containing oxygenated surface functional groups and having nanoporous (microporous and mesoporous) structures. We found that surface properties depend on the LSP:ZnCI2 ratio, carbonization time, and also on the precursor type. The effective surface area increased significantly with increasing LSP:ZnCI2 ratio from 1:0.25 to 1:0.5 and then remain apparently constant. However, total pore volume increased continuously with ZnCI2 ratio. Increase in the carbonization time above 4 h decreased both the surface area and pore volume. ACs prepared from bamboo and coconut shell showed better surface properties compared to AC prepared from sugarcane; surface area and pore volume of the former systems are nearly double of the later system. AC derived from LSP (AC-4) showed excellent electrochemical performance giving specific capacitance value of 328 F/g in 1 M H2SO4 solution demonstrating the potential use of this material for supercapacitor electrodes. Our

  13. Atomic layer deposition of nanoporous biomaterials.

    SciTech Connect

    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.

  14. Structural evolution of self-ordered alumina tapered nanopores with 100 nm interpore distance

    NASA Astrophysics Data System (ADS)

    Li, Juan; Li, Congshan; Gao, Xuefeng

    2011-10-01

    We in-detail investigated the profile evolution processes of highly ordered alumina under the cyclic treatment of mild anodizing of aluminum foils in oxalic acid followed by etching in phosphoric acid. With the cyclic times increasing, the profiles of nanopores were gradually evolved into the parabola-like, trumpet-like and conical shape. Although the inserted etching itself nearly had no impact on the growth rate of the nanopores due to the rapid recovering of thinned barrier layer at the initial stage of next anodizing, overmuch etching could bring apparent side effects such as wall-breaking, thinning and taper-removing from the top down. The anodizing and etching kinetics and their synergetic effects in modulating different aspect ratios and open sizes of conical pores were studied systematically. These findings are helpful to tailor high-quality anodic alumina taper-pores with tunable profiles.

  15. Growth of ZnCdS single crystals and prospects of their application as nanoporous structures

    NASA Astrophysics Data System (ADS)

    Colibaba, G. V.; Monaico, E. V.; Goncearenco, E. P.; Nedeoglo, D. D.; Tiginyanu, I. M.; Nielsch, K.

    2014-12-01

    Substrates of wide band-gap II-VI semiconductor compounds are considered feasible for the fabrication of nanoporous matrices (NM) needed for templated growth of nanowires and nanotubes of solid-state materials promising for applications in various fields. An accessible and cost-effective approach to fabricate NM is based on electrochemical etching (ECE) which, however, depends on the electrical conductivity of the substrates. In this paper, growth of homogeneous ZnxCd1-xS single crystals, with x varying from 0 to 1, is demonstrated and the influence of chemical composition on optical and electrical properties of the crystals is identified. The feasibility of using ZnxCd1-xS alloys with x = 0-0.6 for the growth of nanopore arrays with pore diameter down to 30 nm is shown. The perspectives and limitations of the use of these semiconductor alloys for the fabrication of NM by means of ECE are discussed.

  16. Nanopore Analysis of Nucleic Acids: Single-Molecule Studies of Molecular Dynamics, Structure, and Base Sequence

    NASA Astrophysics Data System (ADS)

    Olasagasti, Felix; Deamer, David W.

    Nucleic acids are linear polynucleotides in which each base is covalently linked to a pentose sugar and a phosphate group carrying a negative charge. If a pore having roughly the crosssectional diameter of a single-stranded nucleic acid is embedded in a thin membrane and a voltage of 100 mV or more is applied, individual nucleic acids in solution can be captured by the electrical field in the pore and translocated through by single-molecule electrophoresis. The dimensions of the pore cannot accommodate anything larger than a single strand, so each base in the molecule passes through the pore in strict linear sequence. The nucleic acid strand occupies a large fraction of the pore's volume during translocation and therefore produces a transient blockade of the ionic current created by the applied voltage. If it could be demonstrated that each nucleotide in the polymer produced a characteristic modulation of the ionic current during its passage through the nanopore, the sequence of current modulations would reflect the sequence of bases in the polymer. According to this basic concept, nanopores are analogous to a Coulter counter that detects nanoscopic molecules rather than microscopic [1,2]. However, the advantage of nanopores is that individual macromolecules can be characterized because different chemical and physical properties affect their passage through the pore. Because macromolecules can be captured in the pore as well as translocated, the nanopore can be used to detect individual functional complexes that form between a nucleic acid and an enzyme. No other technique has this capability.

  17. Effects of tensile strain on the peculiarities of PEO penetration into the nanoporous structure of PET deformed via the crazing mechanism.

    PubMed

    Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2016-04-14

    Solvent crazing involves the development of a highly dispersed fibrillar-porous structure with dimensions of pores and craze fibrils of about 2-20 nm, and crazing by itself can be treated as a universal method for the development of nanoscale porosity. The penetration and release of poly(ethylene oxide) macromolecules into and from the crazes during the development of the nanoporous structure of poly(ethylene terephthalate) have been studied. In particular, PET has been deformed in dilute or semidilute (unentangled as well as entangled) solutions of PEO (a Mw of 4 and 40 kDa) via the mechanism of solvent crazing. Hydrodynamic coil radii Rh, blob sizes ξ, and concentration ranges (crossover and entanglement concentrations) have been determined for the PEO solutions. The evolution of the craze structure (change in porosity W and pore diameters d) has been described as a function of the tensile strain of PET during its drawing in an adsorption-active medium and in the PEO solutions. PEO has been shown to penetrate into the nanoporous structure of the crazes under the conditions corresponding to Rh≤d and ξ < d. It has been shown that coagulation processes in the structure of crazed PET, PEO adsorption at the highly developed surface of PET, and the mechanism of PEO transport in the nanopores are equally important factors affecting the direction of the macromolecule mass transfer in the nanopores (penetration or release) and PEO content variation as a function of PET tensile strain. PMID:26979240

  18. Effects of UV cure on glass structure and fracture properties of nanoporous carbon-doped oxide thin films

    SciTech Connect

    Gage, David M.; Dauskardt, Reinhold H.; Stebbins, Jonathan F.; Peng Luming; Cui Zhenjiang; Al-Bayati, Amir; MacWilliams, Kenneth P.; M'Saad, Hichem

    2008-08-15

    The effects of UV radiation curing on the glass structure and fracture properties were examined for a class of nanoporous organosilicate low dielectric constant films. A detailed characterization by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy showed significant changes in the glass structure with increasing curing time, marked by the removal of terminal organic groups and increased network-forming bonds following the initial removal of porogen material. The higher degree of film connectivity brought about by an increased cure duration is demonstrated to significantly enhance adhesive fracture properties and to moderately improve cohesive fracture resistance. Explanations for the enhanced fracture behavior are considered in terms of the glass structure. The important role of crack path selection during adhesive and cohesive fracture processes is used to rationalize the observed behavior.

  19. Facile synthesis of optical microcavities by a rationally designed anodization approach: tailoring photonic signals by nanopore structure.

    PubMed

    Wang, Ye; Chen, Yuting; Kumeria, Tushar; Ding, Fuyuan; Evdokiou, Andreas; Losic, Dusan; Santos, Abel

    2015-05-13

    Structural engineering of porous anodic aluminum oxide (AAO) nanostructures by anodization has been extensively studied in the past two decades. However, the transition of this technique into the fabrication of AAO-based one-dimensional photonic crystal is still challenging. Herein, we report for the first time on the fabrication of AAO optical microcavities by a rationally designed anodization approach. In our study, two feasible methods are used to fabricate microcavities with tunable resonance peak across the visible and near-infrared spectra. Distributed Bragg reflector (DBR) nanostructures are first fabricated by pulse anodization approach, in which the anodization voltage was periodically manipulated to achieve pseudosinusoidal modulation of the effective refractive index gradient along the depth of the AAO nanostructures. Microcavities were created by creating a nanoporous layer of constant porosity between two AAO-DBR nanostructures, and by introducing a shift of the phase of the porosity gradient along the depth of AAO. The position of the resonance peak in these microcavities can be linearly tuned by means of the duration of the high voltage anodization. These optical nanostructures are sensitive to alterations of the effective media inside the nanopores. The AAO microcavity shows a central wavelength shift of 2.58 ± 0.37 nm when exposed to water vapor. Our research highlights the feasibility of anodization technique to fabricate AAO-based photonic nanostructures for advanced sensing applications. PMID:25901537

  20. Stabilization of graphene nanopore

    PubMed Central

    Lee, Jaekwang; Yang, Zhiqing; Zhou, Wu; Pennycook, Stephen J.; Pantelides, Sokrates T.; Chisholm, Matthew F.

    2014-01-01

    Graphene is an ultrathin, impervious membrane. The controlled introduction of nanoscale pores in graphene would lead to applications that involve water purification, chemical separation, and DNA sequencing. However, graphene nanopores are unstable against filling by carbon adatoms. Here, using aberration-corrected scanning transmission electron microscopy and density-functional calculations, we report that Si atoms stabilize graphene nanopores by bridging the dangling bonds around the perimeter of the hole. Si‐passivated pores remain intact even under intense electron beam irradiation, and they were observed several months after the sample fabrication, demonstrating that these structures are intrinsically robust and stable against carbon filling. Theoretical calculations reveal the underlying mechanism for this stabilization effect: Si atoms bond strongly to the graphene edge, and their preference for tetrahedral coordination forces C adatoms to form dendrites sticking out of the graphene plane, instead of filling the nanopore. Our results provide a novel way to develop stable nanopores, which is a major step toward reliable graphene-based molecular translocation devices. PMID:24821802

  1. Stabilization of graphene nanopore

    SciTech Connect

    Lee, Jaekwang; Yang, Zhiqing; Zhou, Wu; Pennycook, Stephen J.; Pantelides, Sokrates T.; Chisholm, Matthew F.

    2014-05-27

    Graphene is an ultrathin, impervious membrane. The controlled introduction of nanoscale pores in graphene would lead to applications that involve water purification, chemical separation, and DNA sequencing. However, graphene nanopores are unstable against filling by carbon adatoms. Using aberration-corrected scanning transmission electron microscopy and density-functional calculations, we report that Si atoms stabilize graphene nanopores by bridging the dangling bonds around the perimeter of the hole. Si-passivated pores remain intact even under intense electron beam irradiation, and they were observed several months after the sample fabrication, demonstrating that these structures are intrinsically robust and stable against carbon filling. Theoretical calculations reveal the underlying mechanism for this stabilization effect: Si atoms bond strongly to the graphene edge, and their preference for tetrahedral coordination forces C adatoms to form dendrites sticking out of the graphene plane, instead of filling the nanopore. Our results provide a novel way to develop stable nanopores, which is a major step toward reliable graphene-based molecular translocation devices.

  2. Nanoporous frameworks exhibiting multiple stimuli responsiveness

    NASA Astrophysics Data System (ADS)

    Kundu, Pintu K.; Olsen, Gregory L.; Kiss, Vladimir; Klajn, Rafal

    2014-04-01

    Nanoporous frameworks are polymeric materials built from rigid molecules, which give rise to their nanoporous structures with applications in gas sorption and storage, catalysis and others. Conceptually new applications could emerge, should these beneficial properties be manipulated by external stimuli in a reversible manner. One approach to render nanoporous frameworks responsive to external signals would be to immobilize molecular switches within their nanopores. Although the majority of molecular switches require conformational freedom to isomerize, and switching in the solid state is prohibited, the nanopores may provide enough room for the switches to efficiently isomerize. Here we describe two families of nanoporous materials incorporating the spiropyran molecular switch. These materials exhibit a variety of interesting properties, including reversible photochromism and acidochromism under solvent-free conditions, light-controlled capture and release of metal ions, as well reversible chromism induced by solvation/desolvation.

  3. Color-tunable emission of quantum dots via strong exciton-plasmon coupling in nanoporous gold structure at room temperature.

    PubMed

    Zhao, X; Chen, L; Chen, J; Shi, W; Liu, F

    2016-09-01

    We experimentally demonstrate the color-tunable emission of CdTe quantum dots (QDs) enabled by strongly coupling the QDs to the nanoporous gold (NPG) structure at room temperature. By manipulating the concentrations of the QDs or the excitation flux of the laser, the coupling strength between the excitons in QDs and the plasmons in NPG is controlled, resulting in a large Rabi splitting at the magnitude of hundreds of meV and a photoluminescence (PL) tuning distinguishable by the naked eye. In addition, such large PL tuning is enabled not only for the strong coupling occurring on resonance but also off resonance. We believe that our study offers a new approach towards designing and fabricating novel opto-electronic devices where dynamical and large spectral tuning of QD PL emission is desired. PMID:27607629

  4. Closed pyrolyses of the isoprenoid algaenan of Botryococcus braunii, L race: geochemical implications for derived kerogens

    NASA Astrophysics Data System (ADS)

    Behar, F.; Derenne, S.; Largeau, C.

    1995-07-01

    Algaenans, i.e., highly aliphatic, nonhydrolysable, insoluble macromolecular constituents, have been identified in a number of microalga cell walls and their selective preservation shown to play a major role in the formation of numerous kerogens. All the algaenans so far examined comprise a network of long polymethylenic chains, except for the L race of Botryococcus braunii. The resistant macromolecular material isolated from the latter, termed PRB L, is based on C 40 isoprenoid chains with a lycopane-type skeleton. Recent comparative studies of PRB L and of Botryococcus-derived sediments provided the first example of kerogen formation via the selective preservation of an "isoprenoid" algaenan. The present study is concerned with PRB L pyrolyses in sealed gold tubes under various temperature/time conditions (260-350°C, 0.5-69 h). For the conversion rates thus obtained, ranging from 30 to 100%, a complete mass balance of the different families of pyrolysis products was established; most of the C 1 to C 40 pyrolysate constituents were identified and the abundances of the above compounds and their variations with conversion progress were determined. This study thus allowed us (1) to derive further information about PRB L chemical structure (location of the ether bridges, contribution of linear chains and their relationships with the C 40 isoprenoid ones), (2) to determine the behaviour of this isoprenoid algaenan to thermal stress (timing of the formation of the different groups of products then released, nature of the primary cleavages, origin and mode of formation of the secondary products, and further degradations), and (3) to show, in connection with previous studies, that PRB L-derived kerogens should exhibit pronounced differences relative to standard type I kerogens, the latter being based on polymethylenic chains, regarding not only the structure of the generated products but also the timing of oil generation (upward shift of the catagenesis zone).

  5. Optimized nanoporous materials.

    SciTech Connect

    Braun, Paul V.; Langham, Mary Elizabeth; Jacobs, Benjamin W.; Ong, Markus D.; Narayan, Roger J.; Pierson, Bonnie E.; Gittard, Shaun D.; Robinson, David B.; Ham, Sung-Kyoung; Chae, Weon-Sik; Gough, Dara V.; 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.

  6. Noise Properties of Rectifying Nanopore

    SciTech Connect

    Vlassiouk, Ivan V

    2011-01-01

    Ion currents through three types of rectifying nanoporous structures are studied and compared: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by the 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 nonequilibrium 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 nonlinear 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.

  7. Noise Properties of Rectifying Nanopores

    SciTech Connect

    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.

  8. A nanoporous gold membrane for sensing applications

    PubMed Central

    Oo, Swe Zin; Silva, Gloria; Carpignano, Francesca; Noual, Adnane; Pechstedt, Katrin; Mateos, Luis; Grant-Jacob, James A.; Brocklesby, Bill; Horak, Peter; Charlton, Martin; Boden, Stuart A.; Melvin, Tracy

    2016-01-01

    Design and fabrication of three-dimensionally structured, gold membranes containing hexagonally close-packed microcavities with nanopores in the base, are described. Our aim is to create a nanoporous structure with localized enhancement of the fluorescence or Raman scattering at, and in the nanopore when excited with light of approximately 600 nm, with a view to provide sensitive detection of biomolecules. A range of geometries of the nanopore integrated into hexagonally close-packed assemblies of gold micro-cavities was first evaluated theoretically. The optimal size and shape of the nanopore in a single microcavity were then considered to provide the highest localized plasmon enhancement (of fluorescence or Raman scattering) at the very center of the nanopore for a bioanalyte traversing through. The optimized design was established to be a 1200 nm diameter cavity of 600 nm depth with a 50 nm square nanopore with rounded corners in the base. A gold 3D-structured membrane containing these sized microcavities with the integrated nanopore was successfully fabricated and ‘proof of concept’ Raman scattering experiments are described. PMID:26973809

  9. Scaling laws of nanoporous gold under uniaxial compression: Effects of structural disorder on the solid fraction, elastic Poisson's ratio, Young's modulus and yield strength

    NASA Astrophysics Data System (ADS)

    Roschning, B.; Huber, N.

    2016-07-01

    In this work the relationship between the structural disorder and the macroscopic mechanical behavior of nanoporous gold under uniaxial compression was investigated, using the finite element method. A recently proposed model based on a microstructure consisting of four-coordinated spherical nodes interconnected by cylindrical struts, whose node positions are randomly displaced from the lattice points of a diamond cubic lattice, was extended. This was done by including the increased density as result of the introduced structural disorder. Scaling equations for the elastic Poisson's ratio, the Young's modulus and the yield strength were determined as functions of the structural disorder and the solid fraction. The extended model was applied to identify the elastic-plastic behavior of the solid phase of nanoporous gold. It was found, that the elastic Poisson's ratio provides a robust basis for the calibration of the structural disorder. Based on this approach, a systematic study of the size effect on the yield strength was performed and the results were compared to experimental data provided in literature. An excellent agreement with recently published results for polymer infiltrated samples of nanoporous gold with varying ligament size was found.

  10. Nanopore-CMOS Interfaces for DNA Sequencing.

    PubMed

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

    2016-01-01

    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. PMID:27509529

  11. Protein sensing with engineered protein nanopores*

    PubMed Central

    Mohammad, Mohammad M.; Movileanu, Liviu

    2013-01-01

    The use of nanopores is a powerful new frontier in single-molecule sciences. Nanopores have been used effectively in exploring various biophysical features of small polypeptides and proteins, such as their folding state and structure, ligand interactions, and enzymatic activity. In particular, the α-hemolysin protein pore (αHL) has been used extensively for the detection, characterization and analysis of polypeptides, because this protein nanopore is highly robust, versatile and tractable under various experimental conditions. Inspired by the mechanisms of protein translocation across the outer membrane translocases of mitochondria, we have shown the ability to use nanopore-probe techniques in controlling a single protein using engineered αHL pores. Here, we provide a detailed protocol for the preparation of αHL protein nanopores. Moreover, we demonstrate that placing attractive electrostatic traps is instrumental in tackling single-molecule stochastic sensing of folded proteins. PMID:22528256

  12. Analysis of nanopore arrangement and structural features of anodic alumina layers formed by two-step anodizing in oxalic acid using the dedicated executable software

    NASA Astrophysics Data System (ADS)

    Zaraska, Leszek; Stępniowski, Wojciech J.; Sulka, Grzegorz D.; Ciepiela, Eryk; Jaskuła, Marian

    2014-02-01

    Anodic porous alumina layers were fabricated by a two-step self-organized anodization in 0.3 M oxalic acid under various anodizing potentials ranging from 30 to 60 V at two different temperatures (10 and 17 ∘C). The effect of anodizing conditions on structural features and pore arrangement of AAO was investigated in detail by using the dedicated executable publication combined with ImageJ software. With increasing anodizing potential, a linear increase of the average pore diameter, interpore distance, wall thickness and barrier layer thickness, as well as a decrease of the pore density, were observed. In addition, the higher pore diameter and porosity values were obtained for samples anodized at the elevated temperature, independently of the anodizing potential. A degree of pore order was investigated on the basis of Delaunay triangulations (defect maps) and calculation of pair distribution or angle distribution functions (PDF or ADF), respectively. All methods confirmed that in order to obtain nanoporous alumina with the best, hexagonal pore arrangement, the potential of 40 V should be applied during anodization. It was confirmed that the dedicated executable publication can be used to a fast and complex analysis of nanopore arrangement and structural features of nanoporous oxide layers.

  13. Nanoporous plasmonic metamaterials

    SciTech Connect

    Biener, J; Nyce, G W; Hodge, A M; Biener, M M; Hamza, A V; Maier, S A

    2007-05-24

    We review different routes for the generation of nanoporous metallic foams and films exhibiting well-defined pore size and short-range order. Dealloying and templating allows the generation of both two- and three-dimensional structures which promise a well defined plasmonic response determined by material constituents and porosity. Viewed in the context of metamaterials, the ease of fabrication of samples covering macroscopic dimensions is highly promising, and suggests more in-depth investigations of the plasmonic and photonic properties of this material system for photonic applications.

  14. Highly cross-linked nanoporous polymers

    DOEpatents

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

    1997-01-01

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

  15. Highly cross-linked nanoporous polymers

    DOEpatents

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

    1998-01-01

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

  16. Struvite pyrolysate recycling combined with dry pyrolysis for ammonium removal from wastewater.

    PubMed

    Yu, Rongtai; Geng, Jinju; Ren, Hongqiang; Wang, Yanru; Xu, Ke

    2013-03-01

    The dry pyrolysis of magnesium ammonium phosphate (MAP) with NaOH powder for ammonium release was investigated, as well as the utility of MAP pyrolysate recycling. The identities of the MAP pyrolysate and its derivatives were experimentally validated. The results showed that the pyrolysate was amorphous magnesium hydrogen phosphate (MgHPO4) and magnesium pyrophosphate (Mg2P2O7). The best molar ratio of sodium hydroxide (NaOH) powder to ammonium was 1:1, at 110°C for 3h. The optimum pH for pyrolysate recycling was 9.5. The ammonia removal ratio could be maintained above 80% with MAP pyrolysate recycling. Seed crystal inoculation increased the rate of MAP crystallization by 20.86%, as well as the MAP grain size (2.08nm with seeding versus 1.72nm without). MAP particle size with NaOH treatment decreased: d(0.5)=19.34μm versus d(0.5)=30.35μm for direct pyrolysis. The results demonstrated that crystal growth was controlled by adding NaOH during MAP pyrolysis. PMID:23395767

  17. Watching Single Proteins Using Engineered Nanopores

    PubMed Central

    Movileanu, Liviu

    2014-01-01

    Recent studies in the area of single-molecule detection of proteins with nanopores show a great promise in fundamental science, bionanotechnology and proteomics. In this mini-review, I discuss a comprehensive array of examinations of protein detection and characterization using protein and solid-state nanopores. These investigations demonstrate the power of the single-molecule nanopore measurements to reveal a broad range of functional, structural, biochemical and biophysical features of proteins, such as their backbone flexibility, enzymatic activity, binding affinity as well as their concentration, size and folding state. Engineered nanopores in organic materials and in inorganic membranes coupled with surface modification and protein engineering might provide a new generation of sensing devices for molecular biomedical diagnosis. PMID:24370252

  18. Nanoporous Structure and Medium-Range Order in Synthetic Amorphous Calcium Carbonate

    SciTech Connect

    Goodwin, Andrew L.; Michel, F. Marc; Phillips, Brian L.; Keen, David A.; Dove, Martin T.; Reeder, Richard J.

    2010-12-03

    We adopt a reverse Monte Carlo refinement approach, using experimental X-ray total scattering data, to develop a structure model for synthetic, hydrated amorphous calcium carbonate (ACC). The ACC is revealed to consist of a porous calcium-rich framework that supports interconnected channels containing water and carbonate molecules. The existence of a previously unrecognized nanometer-scale channel network suggests mechanisms of how additives can be accommodated within the structure and provide temporary stabilization, as well as influence the crystallization process. Moreover, while lacking long-range order, the calcium-rich framework in the ACC contains similar Ca packing density to that present in calcite, aragonite, and vaterite, yielding clues of how the amorphous material converts into the different crystalline forms. Our results provide a new starting point for advancing our understanding of biomineralization as well as the development of biomimetic approaches to next-generation materials synthesis.

  19. Molecular structure and dynamics of an aqueous sodium chloride solution in nano-pores between portlandite surfaces: a molecular dynamics study.

    PubMed

    Dongshuai, Hou; Zeyu, Lu; Peng, Zhang; Qingjun, Ding

    2016-01-21

    Portlandite plays an important role in the hydration phase of cement-based materials and influences the strength and durability of such materials. This study describes a molecular dynamics study of the structure and dynamics of water and ions confined at ambient temperature in calcium hydroxyl nanopores with widths of 35 Å. Strong layering of water in the vicinity of the (001) surface of portlandite demonstrates special structural features such as large density, good orientation preference, ordered interfacial organization and low diffusion rate. Due to the fixed vibration and rotation of the hydroxyl groups at the interface, water molecules within the first adsorbed layer adopt both H-downward and H-upward orientations by donating H-bonds and accepting H-bonds from the OH groups in the solid surface. Regarding the interaction of the ions and portlandite, Na(+) ions, deeply rooted in spaces in the surface hydroxyl groups, are significantly slowed and remain near the surface for long periods of time. On the other hand, due to the weak H-bonds formed by chloride ions and hydroxyl groups, adsorbed chloride ions near the surface cannot remain for longer times. In addition, when water and ions are confined in the nano-pores, the residence time for the ion-water and ion-ion clusters is lengthened so that the ion adsorption capability of the porlandite surface is enhanced due to the stable Na-Cl connections in the electrolyte solution. PMID:26687688

  20. Transformation of self-assembly of a TTF derivative at the 1-phenyloctane/HOPG interface studied by STM--from a nanoporous network to a linear structure

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Xiao, Xunwen; Deng, Ke; Zeng, Qingdao

    2016-01-01

    The self-assembly of a tetrathiafulvalene (TTF) derivative (EDTTF) and a 1,3,5-tris(10-carboxydecyloxy)-benzene (TCDB) heterobilayer nanostructure at the 1-phenyloctane/HOPG interface under ambient conditions has been studied by scanning tunneling microscopy (STM). EDTTF and TCDB could co-assemble into a brand new hexagonal network with one of the largest nano-cavities. Finally, the nanoporous network would transform into a more stable linear structure. Density functional theory (DFT) calculations have been performed to reveal the formation mechanism.The self-assembly of a tetrathiafulvalene (TTF) derivative (EDTTF) and a 1,3,5-tris(10-carboxydecyloxy)-benzene (TCDB) heterobilayer nanostructure at the 1-phenyloctane/HOPG interface under ambient conditions has been studied by scanning tunneling microscopy (STM). EDTTF and TCDB could co-assemble into a brand new hexagonal network with one of the largest nano-cavities. Finally, the nanoporous network would transform into a more stable linear structure. Density functional theory (DFT) calculations have been performed to reveal the formation mechanism. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07345f

  1. Membrane platforms for biological nanopore sensing and sequencing.

    PubMed

    Schmidt, Jacob

    2016-06-01

    In the past two decades, biological nanopores have been developed and explored for use in sensing applications as a result of their exquisite sensitivity and easily engineered, reproducible, and economically manufactured structures. Nanopore sensing has been shown to differentiate between highly similar analytes, measure polymer size, detect the presence of specific genes, and rapidly sequence nucleic acids translocating through the pore. Devices featuring protein nanopores have been limited in part by the membrane support containing the nanopore, the shortcomings of which have been addressed in recent work developing new materials, approaches, and apparatus resulting in membrane platforms featuring automatability and increased robustness, lifetime, and measurement throughput. PMID:26773300

  2. Improving mechanical fatigue resistance by optimizing the nanoporous structure of inkjet-printed Ag electrodes for flexible devices

    NASA Astrophysics Data System (ADS)

    Kim, Byoung-Joon; Haas, Thomas; Friederich, Andreas; Lee, Ji-Hoon; Nam, Dae-Hyun; Binder, Joachim R.; Bauer, Werner; Choi, In-Suk; Joo, Young-Chang; Gruber, Patric A.; Kraft, Oliver

    2014-03-01

    The development of highly conductive metallic electrodes with long-term reliability is in great demand for real industrialization of flexible electronics, which undergo repeated mechanical deformation during service. In the case of vacuum-deposited metallic electrodes, adequate conductivity is provided, but it degrades gradually during cyclic mechanical deformation. Here, we demonstrate a long-term reliable Ag electrode by inkjet printing. The electrical conductivity and the mechanical reliability during cyclic bending are investigated with respect to the nanoporous microstructure caused by post heat treatment, and are compared to those of evaporated Ag films of the same thickness. It is shown that there is an optimized nanoporous microstructure for inkjet-printed Ag films, which provides a high conductivity and improved reliability. It is argued that the nanoporous microstructure ensures connectivity within the particle network and at the same time reduces plastic deformation and the formation of fatigue damage. This concept provides a new guideline to develop an efficient method for highly conductive and reliable metallic electrodes for flexible electronics.

  3. Structural and optical characterization of fresh water diatoms (Cyclotella sp.): nature's nanoporous silica manufacturing plant

    NASA Astrophysics Data System (ADS)

    Mazumder, Nirmal; Gogoi, Ankur; Buragohain, Alak K.; Ahmed, Gazi A.; Choudhury, Amarjyoti

    2014-02-01

    Siliceous frustules were extracted from a representative fresh water diatom species (Cyclotella sp.) by treating with aqueous hydrochloric (HCl) acid. The structural characterizations of cleaned frustules were examined by scanning electron microscope (SEM). The microscopy images showed that the diatoms have a regular circular shape and are of almost equal size (average length is 9μm and average width is 3 μm). From energy dispersive X -ray spectroscopy (SEM-EDS) spot analysis it was confirmed that the frustules isolated from diatoms are composed mainly of silicon in the form of amorphous silica (SiO2). The bond information of chemical substances of diatom frustules was carried out at ambient temperature by means of Fourier Transform Infrared (FTIR) Spectroscopy. FTIR spectrum as recorded in transmittance mode showed the characteristic peaks for diatom biosilica, including for Si-O-Si stretching vibration at 1057 and 776 cm-1. Photoluminescence (PL) measurements of diatom frustules were performed at room temperature and it was observed that they emitted strong blue PL centered at 440nm when excited with ultraviolet (UV) radiation.

  4. Nanoporous polymer electrolyte

    SciTech Connect

    Elliott, Brian; Nguyen, Vinh

    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.

  5. Controlling interfacial curvature in nanoporous silica films formed by evaporation-induced self-assembly from nonionic surfactants. I. Evolution of nanoscale structures in coating solutions.

    PubMed

    Bollmann, Luis; Urade, Vikrant N; Hillhouse, Hugh W

    2007-04-10

    The double-gyroid phase of nanoporous silica films formed by evaporation-induced self-assembly (EISA) has been shown to possess facile mass-transport properties and may be used as a robust template for the nanofabrication of metal and semiconductor nanostructures. Recently, we developed a new synthesis of double-gyroid nanoporous silica films where the aging time of the coating solution prior to EISA was the key parameter required to control the interfacial curvature that results upon self-assembly of the film. Here, we use 29Si nuclear magnetic resonance (NMR) and small-angle X-ray scattering (SAXS) to investigate the nanoscale structure of the coating solutions used to obtain double-gyroid nanoporous silica films. NMR and SAXS were carried out on the water, ethanol, silica, and poly(ethylene oxide)-b-poly(propylene oxide)-b-alkyl (EO17-PO12-C14) surfactant coating solutions as well as similar solutions that excluded either the silica or the surfactant. NMR data reveal that the silica monomers in the coating solution condense very rapidly to form rings and connected ring species. After 1 day of aging, all monomers and dimers have disappeared, and the distribution is dominated by Q2 and Q3 species, where the superscript in Qn describes the number of silicon atoms in the second coordination shell of the central silicon. Over the course of the next 9 days, the Q3 population slowly rises at the expense of the Q2 and Q3t populations. Absolute intensity SAXS measurements reveal that the size of the silica clusters increases steadily during this aging period, reaching an average radius of gyration of 9.0 A after 9 days of aging. Longer aging results in the continued growth of clusters with a mass fractal dimension of 1.8. Absolute intensity SAXS data also reveals that micelles are not present in the coating solution. At 9% volume fraction of surfactant, the coating solution is far above the aqueous critical micellar concentration. However, even a small amount of ethanol

  6. Deformation Behavior of Nanoporous Metals

    SciTech Connect

    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

  7. Optical Properties of Nanoporous Germanium Thin Films.

    PubMed

    Cavalcoli, Daniela; Impellizzeri, Giuliana; Romano, Lucia; Miritello, Maria; Grimaldi, Maria Grazia; Fraboni, Beatrice

    2015-08-12

    In the present article we report enhanced light absorption, tunable size-dependent blue shift, and efficient electron-hole pairs generation in Ge nanoporous films (np-Ge) grown on Si. The Ge films are grown by sputtering and molecular beam epitaxy; subsequently, the nanoporous structure is obtained by Ge+ self-implantation. We show, by surface photovoltage spectroscopy measurements, blue shift of the optical energy gap and strong signal enhancement effects in the np-Ge films. The blue shift is related to quantum confinement effects at the wall separating the pore in the structure, the signal enhancement to multiple light-scattering events, which result in enhanced absorption. All these characteristics are highly stable with time. These findings demonstrate that nanoporous Ge films can be very promising for photovoltaic applications. PMID:26177652

  8. Diterpanes, triterpanes, steranes, and aromatic hydrocarbons in natural bitumens and pyrolysates from different humic coals

    NASA Astrophysics Data System (ADS)

    Lu, Shan-Tan; Kaplan, Isaac R.

    1992-07-01

    Data are presented on the distribution of diterpanes, triterpanes, steranes, and aromatic hydrocarbons in the natural bitumens extracted from unheated coals identified as Rocky Mountain coal (RMC), Australian Gippsland Latrobe Eocene coal (GEC), Australian Gippsland Latrobe Cretaceous coal (GCC), and Texas Wilcox lignite (WL), as well as from pyrolysates obtained from heating of these coals. It was found that pentacyclic triterpanes are dominant in GEC, GCC, and WL, whereas diterpanes strongly predominate in the bitumen of RMC, indicating that resin is a more important constituent of RMC than of the other coals and that it releases the diterpenoids at an early stage of diagenesis. It was also found that the composition of diterpanes is different among these coals and that the distributions of sterane and triterpane in the natural bitumen of coals are very different from those of pyrolysates.

  9. Diterpanes, triterpanes, steranes, and aromatic hydrocarbons in natural bitumens and pyrolysates from different humic coals

    NASA Technical Reports Server (NTRS)

    Lu, Shan-Tan; Kaplan, Isaac R.

    1992-01-01

    Data are presented on the distribution of diterpanes, triterpanes, steranes, and aromatic hydrocarbons in the natural bitumens extracted from unheated coals identified as Rocky Mountain coal (RMC), Australian Gippsland Latrobe Eocene coal (GEC), Australian Gippsland Latrobe Cretaceous coal (GCC), and Texas Wilcox lignite (WL), as well as from pyrolysates obtained from heating of these coals. It was found that pentacyclic triterpanes are dominant in GEC, GCC, and WL, whereas diterpanes strongly predominate in the bitumen of RMC, indicating that resin is a more important constituent of RMC than of the other coals and that it releases the diterpenoids at an early stage of diagenesis. It was also found that the composition of diterpanes is different among these coals and that the distributions of sterane and triterpane in the natural bitumen of coals are very different from those of pyrolysates.

  10. Levoglucosan and other cellulose markers in pyrolysates of Miocene lignites: geochemical and environmental implications

    SciTech Connect

    Daniele Fabbri; Leszek Marynowski; Monika J. Fabianska; Michal Zaton; Bernd R.T. Simoneit

    2008-04-15

    Using the pyrolysis-gas chromatography-mass spectrometry and off-line pyrolysis/silylation methods for lignites from three Miocene brown coal basins of Poland resulted in the characterization of many organic compounds, including dominant cellulose degradation products such as levoglucosan, 1,6-anhydro-{beta}-D-glucofuranose, and 1,4:3,6-dianhydroglucopyranose. Levoglucosan is a general source-specific tracer for wood smoke in the atmosphere and recent sediments. The presence of unusually high levels of this compound in brown coal pyrolysates suggests that a portion of this compound concentration in some airsheds may originate from lignite combustion. On the other hand, nonglucose anhydrosaccharides, in particular, mannosan and galactosan, typical of hemicellulose, are not detected in those lignite pyrolysates investigated. This indicates that mannosan and galactosan are better specific tracers for combustion of contemporary biomass in those regions where the utilization of brown coals containing fossilized cellulose is important. 7 refs., 2 figs., 3 tabs.

  11. Lipid Bilayer Membrane Perturbation by Embedded Nanopores: A Simulation Study.

    PubMed

    Garcia-Fandiño, Rebeca; Piñeiro, Ángel; Trick, Jemma L; Sansom, Mark S P

    2016-03-22

    A macromolecular nanopore inserted into a membrane may perturb the dynamic organization of the surrounding lipid bilayer. To better understand the nature of such perturbations, we have undertaken a systematic molecular dynamics simulation study of lipid bilayer structure and dynamics around three different classes of nanopore: a carbon nanotube, three related cyclic peptide nanotubes differing in the nature of their external surfaces, and a model of a β-barrel nanopore protein. Periodic spatial distributions of several lipid properties as a function of distance from the nanopore were observed. This was especially clear for the carbon nanotube system, for which the density of lipids, the bilayer thickness, the projection of lipid head-to-tail vectors onto the membrane plane, and lipid lateral diffusion coefficients exhibited undulatory behavior as a function of the distance from the surface of the channel. Overall, the differences in lipid behavior as a function of the nanopore structure reveal local adaptation of the bilayer structure and dynamics to different embedded nanopore structures. Both the local structure and dynamic behavior of lipids around membrane-embedded nanopores are sensitive to the geometry and nature of the outer surface of the macromolecule/molecular assembly forming the pore. PMID:26943498

  12. Micro-nanopores fabricated by high-energy electron beam irradiation: suitable structure for controlling pesticide loss.

    PubMed

    Xiang, Yubin; Wang, Ning; Song, Jimei; Cai, Dongqing; Wu, Zhengyan

    2013-06-01

    Pesticide sprayed onto crop leaves tends to be washed off by rainwater and discharge into the environment through leaching and runoff, resulting in severe pollution to both soil and water. Here, to control pesticide loss, we developed a loss-control pesticide (LCP) by adding modified natural nanoclay (diatomite) through high-energy electron beam (HEEB) to traditional pesticide. After HEEB treatment, the originally clogged pores in diatomite opened, resulting in plenty of micro-nanopores in diatomite, which are beneficial for the pesticide molecules to access and be adsorbed. This pesticide-diatomite complex tended to be retained by the rough surface of crop leaves, displaying a high adhesion performance onto the leaves, so that the pesticide loss reduced, sufficient pesticide for crops was supplied, and the pollution risk of the pesticide could be substantially lowered. PMID:23672373

  13. Entropic cages for trapping DNA near a nanopore

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    PubMed

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

    2016-01-01

    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. PMID:27499264

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

    PubMed Central

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

    2016-01-01

    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. PMID:27499264

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Nanopore sculpting with noble gas ions.

    PubMed

    Cai, Qun; Ledden, Brad; Krueger, Eric; Golovchenko, Jene A; Li, Jiali

    2006-01-01

    We demonstrate that 3 keV ion beams, formed from the common noble gasses, He, Ne, Ar, Kr, and Xe, can controllably "sculpt" nanometer scale pores in silicon nitride films. Single nanometer control of structural dimensions in nanopores can be achieved with all ion species despite a very wide range of sputtering yields and surface energy depositions. Heavy ions shrink pores more efficiently and make thinner pores than lighter ions. The dynamics of nanopore closing is reported for each ion species and the results are fitted to an adatom diffusion model with excellent success. We also present an experimental method for profiling the thickness of the local membrane around the nanopore based on low temperature sputtering and data is presented that provides quantitative measurements of the thickness and its dependence on ion beam species. PMID:21331305

  18. Rapid nanopore discrimination between single polynucleotide molecules

    PubMed Central

    Meller, Amit; Nivon, Lucas; Brandin, Eric; Golovchenko, Jene; Branton, Daniel

    2000-01-01

    A variety of different DNA polymers were electrophoretically driven through the nanopore of an α-hemolysin channel in a lipid bilayer. Single-channel recording of the translocation duration and current flow during traversal of individual polynucleotides yielded a unique pattern of events for each of the several polymers tested. Statistical data derived from this pattern of events demonstrate that in several cases a nanopore can distinguish between polynucleotides of similar length and composition that differ only in sequence. Studies of temperature effects on the translocation process show that translocation duration scales as ∼T−2. A strong correlation exists between the temperature dependence of the event characteristics and the tendency of some polymers to form secondary structure. Because nanopores can rapidly discriminate and characterize unlabeled DNA molecules at low copy number, refinements of the experimental approach demonstrated here could eventually provide a low-cost high-throughput method of analyzing DNA polynucleotides. PMID:10655487

  19. A novel hierarchically structured and highly hydrophilic poly(vinyl alcohol-co-ethylene)/poly(ethylene terephthalate) nanoporous membrane for lithium-ion battery separator

    NASA Astrophysics Data System (ADS)

    Xia, Ming; Liu, Qiongzhen; Zhou, Zhou; Tao, Yifei; Li, MuFang; Liu, Ke; Wu, Zhihong; Wang, Dong

    2014-11-01

    A novel hierarchically structured and highly hydrophilic poly(vinyl alcohol-co-ethylene)/poly(ethylene terephthalate) nanoporous separator (referred to NFs/PET/NFs) composed of a poly(ethylene terephthalate) (PET) nonwoven sandwiched between two interconnected poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membranes is successfully developed for lithium-ion battery. Systematical investigations including structural characterization, porosity measurement, water contact angle testing, electrolyte uptake, and thermal shrinkage testing demonstrate that the notable feature of this NFs/PET/NFs nanofibrous separator is an electrolyte-philic, highly porous and hierarchically nanoscaled structure, thus resulting in superior electrolyte wettability, lower thermal shrinkage, and higher ion conductivity, in comparison to the commercial Polypropylene (PP) separator. These structural characteristics enable the NFs/PET/NFs separator to offer an excellent cell performance including outstanding C-rate capability, high capacity and excellent cycling performance. This suggests that the NFs/PET/NFs separator is a promising material for practical application in lithium-ion battery due to it low cost production and high performance.

  20. Thermal Conductivity in Nanoporous Gold Films during Electron-Phonon Nonequilibrium

    DOE PAGESBeta

    Hopkins, Patrick E.; Norris, Pamela M.; Phinney, Leslie M.; Policastro, Steven A.; Kelly, Robert G.

    2008-01-01

    The reduction of nanodevices has given recent attention to nanoporous materials due to their structure and geometry. However, the thermophysical properties of these materials are relatively unknown. In this article, an expression for thermal conductivity of nanoporous structures is derived based on the assumption that the finite size of the ligaments leads to electron-ligament wall scattering. This expression is then used to analyze the thermal conductivity of nanoporous structures in the event of electron-phonon nonequilibrium.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  2. Nanoporous silicon oxide memory.

    PubMed

    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. PMID:24992278

  3. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, W.P. Jr.; Apen, P.G.; Mitchell, M.A.

    1998-01-20

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes. 1 fig.

  4. Electrochemistry at Edge of Single Graphene Layer in a Nanopore

    PubMed Central

    Banerjee, Shouvik; Shim, Jiwook; Rivera, Jose; Jin, Xiaozhong; Estrada, David; Solovyeva, Vita; You, Xiuque; Pak, James; Pop, Eric; Aluru, Narayana; Bashir, Rashid

    2013-01-01

    We study the electrochemistry of single layer graphene edges using a nanopore-based structure consisting of stacked graphene and Al2O3 dielectric layers. Nanopores, with diameters ranging from 5 to 20 nm, are formed by an electron beam sculpting process on the stacked layers. This leads to unique edge structure which, along with the atomically thin nature of the embedded graphene electrode, demonstrates electrochemical current densities as high as 1.2 × 104 A/cm2. The graphene edge embedded structure offers a unique capability to study the electrochemical exchange at an individual graphene edge, isolated from the basal plane electrochemical activity. We also report ionic current modulation in the nanopore by biasing the embedded graphene terminal with respect to the electrodes in the fluid. The high electrochemical specific current density for a graphene nanopore-based device can have many applications in sensitive chemical and biological sensing, and energy storage devices. PMID:23249127

  5. a Simple Method to Prepare Nanoporous Sn:Pb Composite Metal Foam

    NASA Astrophysics Data System (ADS)

    Zandi, Majid; Amirhoseiny, Maryam; Mosayyebi, Abolghasem

    2015-03-01

    A novel and simple approach for preparing nanoporous binder free Sn:Pb composite metal foam has been demonstrated. The anodized metallic composite block was functionalized and also found a nanoporous structure. A scanning electron microscopy (SEM) result shows that the nanoflake-like arrangement has synthesized. The X-ray diffraction (XRD) results confirm the nanoporous structure of the Sn/Pb foam after etching with 6 M NaOH. The prepared Sn:Pb metal foam is able to be used as a super capacitors electrode to offer large areal capacitance with regards to the synergic integration of Sn and Pb metals and the unique nanoporous structure.

  6. Fluorescence biosensing in nanopores.

    PubMed

    Karolin, Jan; Pánek, Dalibor; MacMillan, Alexander; Rolinski, Olaf; Birch, David

    2009-01-01

    Hydrated nanopores offer a unique environment for studying biological molecules under controlled conditions and fabricating sensors using fluorescence. Silica nanopores for example are non-toxic, biologically and optically compatible with protein, and can be easily synthesized to entrap protein and exclude potentially interfering macromolecules, while transmitting analytes of interest. A well known problem when polymerizing orthosilicates to fabricate silica sol-gel nanopores is the release of alcohol, which denatures proteins. We will describe how using the fluorescence of PRODAN (6-propionyl-2-(N,N-dimethylamino) naphthalene) to monitor methanol generated during polymerization has helped define a protocol with enhanced biocompatibility. The improved biocompatibility of sol-gel nanopores synthesized using tetramethyl orthosilicate (TMOS) has been demonstrated by preserving the unstable native trimer form of allophycocyanin (APC) for up to 500 Hrs without the need to covalently binding the subunits together. This has enabled the observation of native APC trimer by means of its fluorescence in a pore down to the single molecule level. In this paper we demonstrate how PRODAN and another polarity sensitive dye, 9-diethylamino-5H-benzo[alpha]phenoxazine-5-one, Nile red (NR) report on pore polarity and successfully extend protein encapsulation to nano-channels of alumina (Al2O3). Improved biocompatibility of nanopores has potential impact in nanomedicine where the ability to study single biomolecules is a primary goal as it underpins our understanding of disease pathology and therapeutics at the most fundamental level. In sensing also the advantages of nanopore isolation of metabolite-specific protein for detecting non-fluorescent metabolites has been demonstrated. Similar approaches can in principle be developed for both single-molecules and lab-on-a-chip sensors. PMID:19964618

  7. Surface Electronic Properties and Site-Specific Laser Desorption Processes of Highly Structured Nanoporous MgO Thin Films

    SciTech Connect

    Henyk, Matthias; Beck, Kenneth M.; Engelhard, Mark H.; Joly, Alan G.; Hess, Wayne P.; Dickinson, J T.

    2005-11-20

    The surface electronic properties of metal oxides critically depends on low-coordinated sites, such as kinks, corners and steps [1]. In order to characterize experimentally those surface states as well as their role for laser desorption processes, we prepare defect enriched surfaces by growing thin MgO films using reactive ballistic deposition [2] on crystalline dielectric substrates. With samples held at room temperature, the resulting MgO films are highly textured and consist of porous columns with column lengths ranging from tens of nanometers up to six micrometers. Measurements by x-ray photoelectron spectroscopy (XPS) are carried out in-situ for MgO films, vacuum-cleaved MgO crystals, and water vapor exposed samples. In the case of thin films, we observe O 1s spectra with a significant shoulder feature at 2.3 eV higher binding energy (HBE) than the corresponding peak at 530.0 eV representing regular lattice oxygen. We evaluate this feature in terms of non-stoichiometric oxygen and formation of an oxygen-rich layer at the topmost surface of the MgO columns. In contrast, no HBE-features are detectable from clean single crystal MgO surfaces, while the hydroxyl O 1s band peaks at 531.6 eV. Under excitation with 266-nm-laser-pulses, known to be resonant with low-coordinated surface anions [3], we observe preferential depletion of defective oxygen-states (HBE signal) and temporary restoration of ideal surface stoichiometry. Furthermore, auxiliary signals are observed on several micrometer thick films, acting like satellites to major photoelectron-peaks (O 1s, Mg 2s, and Mg 2p) but shifted by approximately 4 eV towards lower kinetic energy. These features are depleted by UV-light exposure, pointing to the occurrence of surface-charge imbalance, accompanied by photon stimulated charge-transfer reactions. These results are in line with desorption experiments of neutrals, stimulated by laser excitation at 266 nm. According to the low-coordination nature of nanoporous Mg

  8. Monitoring protein adsorption with solid-state nanopores.

    PubMed

    Niedzwiecki, David J; Movileanu, Liviu

    2011-01-01

    Solid-state nanopores have been used to perform measurements at the single-molecule level to examine the local structure and flexibility of nucleic acids, the unfolding of proteins, and binding affinity of different ligands. By coupling these nanopores to the resistive-pulse technique, such measurements can be done under a wide variety of conditions and without the need for labeling. In the resistive-pulse technique, an ionic salt solution is introduced on both sides of the nanopore. Therefore, ions are driven from one side of the chamber to the other by an applied transmembrane potential, resulting in a steady current. The partitioning of an analyte into the nanopore causes a well-defined deflection in this current, which can be analyzed to extract single-molecule information. Using this technique, the adsorption of single proteins to the nanopore walls can be monitored under a wide range of conditions. Protein adsorption is growing in importance, because as microfluidic devices shrink in size, the interaction of these systems with single proteins becomes a concern. This protocol describes a rapid assay for protein binding to nitride films, which can readily be extended to other thin films amenable to nanopore drilling, or to functionalized nitride surfaces. A variety of proteins may be explored under a wide range of solutions and denaturing conditions. Additionally, this protocol may be used to explore more basic problems using nanopore spectroscopy. PMID:22157952

  9. Film Growth on Nanoporous Substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Joy, James; Zhao, Chenwei; Xu, J. M.; Valles, James

    Self-ordered nanoporous anodic aluminum oxide (AAO) provides an easy way to fabricate nano structured material, such as nano wires and nano particles. We employ AAO as substrates and focus on the thermally evaporated film growth on the surface of the substrate. With various materials deposited onto the substrate, we find the films show different structures, e,g. ordered array of nano particles for Lead and nanohoneycomb structure for Silver. We relate the differing behaviors to the difference of surface energy and diffusion constant. To verify this, the effect of substrate temperature on the film growth has been explored and the structure of the film has been successfully changed through the process. We are grateful for the support of NSF Grants No. DMR-1307290.

  10. A nanoporous polymer film as a diffuser as well as a light extraction component for top emitting organic light emitting diodes with a strong microcavity structure

    NASA Astrophysics Data System (ADS)

    Pyo, Beom; Joo, Chul Woong; Kim, Hyung Suk; Kwon, Byoung-Hwa; Lee, Jeong-Ik; Lee, Jonghee; Suh, Min Chul

    2016-04-01

    To improve the viewing angle characteristic as well as the light extraction effect of strong microcavity devices, we fabricated a nanoporous polymer film (NPF) as a scattering medium as well as a light extraction component. We designed two types of organic light emitting diodes (OLEDs) with a strong microcavity effect by changing the thickness of the hole transport layer (HTL; e.g. 30 nm and 60 nm) to investigate two different scattering effects of the NPF. Very interestingly, we could observe a significant enhancement of the external quantum efficiency (EQE) for each device (30 nm thick HTL: 18.0%, 60 nm thick HTL: 31.6%) when we attached a NPF formed on a 125 μm thick PET film coated with the NPF. Furthermore, the NPF successfully suppressed the viewing angle dependence to realize ideal angular emission even in the two extreme microcavity conditions although they are still different from that of a Lambertian distribution.To improve the viewing angle characteristic as well as the light extraction effect of strong microcavity devices, we fabricated a nanoporous polymer film (NPF) as a scattering medium as well as a light extraction component. We designed two types of organic light emitting diodes (OLEDs) with a strong microcavity effect by changing the thickness of the hole transport layer (HTL; e.g. 30 nm and 60 nm) to investigate two different scattering effects of the NPF. Very interestingly, we could observe a significant enhancement of the external quantum efficiency (EQE) for each device (30 nm thick HTL: 18.0%, 60 nm thick HTL: 31.6%) when we attached a NPF formed on a 125 μm thick PET film coated with the NPF. Furthermore, the NPF successfully suppressed the viewing angle dependence to realize ideal angular emission even in the two extreme microcavity conditions although they are still different from that of a Lambertian distribution. Electronic supplementary information (ESI) available: The theoretical backgrounds associated with designing of microcavity

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

    DOEpatents

    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.

  12. Mutagenic activity of pyrolysates of cyanocobalamin and some other water-soluble vitamins in the model system with the Salmonella/mammalian microsomes.

    PubMed

    Demura, R; Tsukada, S; Kotani, N; Tateoka, Y; Narimatsu, S; Yamamoto, I

    1990-05-01

    Pyrolysates of cyanocobalamin, thiamine hydrochloride, riboflavin, pyridoxine hydrochloride, and ascorbic acid were tested for mutagenicity in the histidine-requiring mutants Salmonella typhimurium TA98 and TA100. Each vitamin was sealed in a glass tube and heated at 100-600 degrees C in a muffle furnace. Methanol-chloroform extracts of the pyrolysate of each vitamin tested did not show any mutagenicity in either TA98 or TA100 without rat liver 9000 x g supernatant fraction (S9) added. In the presence of S9, the B-group vitamins (cyanocobalamin, thiamine hydrochloride, riboflavin, and pyridoxine hydrochloride) were all mutagenic in TA98 and TA100, with the highest activity among the vitamins tested found in the pyrolysate of cyanocobalamin. The pyrolysate of 0.25 mumole cyanocobalamin produced 3200 revertants, while the pyrolysates of 0.25 mumole thiamine hydrochloride and riboflavin produced only 910 revertants, and the pyrolysate of pyridoxine hydrochloride did not show any mutagenicity at that amount. The mutagenicity was generally more active to TA98 than to TA100, indicating that frameshift-type mutagens were contained in the pyrolysates. The pyrolysate of ascorbic acid did not show any mutagenic activity in either TA98 or TA100 under the present experimental conditions. PMID:2186270

  13. Relative toxicity testing of spacecraft materials. 1: Spacecraft materials. [lethality of pyrolysates

    NASA Technical Reports Server (NTRS)

    Lawrence, W. H.

    1980-01-01

    In chamber thermodegradation procedures were used to access the lethality to rats of the pyrolysis/combustion products of three foams, an adhesive backed metallic tape and RTV silicone rubber adhesive sealant used in spacecraft construction. The role of carbon monoxide in the overall pyrolysate toxicity was also investigated. Post exposure observation of the rats, histological evaluation of selected organs, carbon monoxide concentration in the chamber atmosphere during exposure and the percent carboxyhemoglobin in the animals expiring in the chamber are discussed. Thermogravimetric analysis and dosage response results are given. The lethal effect of the RTV silicon appears to be due to physical obstruction of the respiratory system by particulate matter from pyrolysis.

  14. Substrate effect on nanoporous structure of silica wires by channel-confined self-assembly of block-copolymer and sol-gel precursors

    DOE PAGESBeta

    Hu, Michael Z.; Lai, Peng

    2015-09-22

    Nanoporous silica wires of various wire diameters were developed by space-confined molecular self-assembly of triblock copolymer ethylene/propylene/ethylene (P123) and silica alkoxide precursor (tetraethylorthosilicate, TEOS). Two distinctive hard-templating substrates, anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC), with channel diameters in the range between 10 nm and 200 nm were employed for space-confinement of soft molecular self-assembly driven by the block-copolymer microphase separation. It was observed in the scanning and transmission electron microscope (STEM) studies that the substrate geometry and material characteristics had pronounced effects on the structure and morphology of the silica nanowires. A substrate wall effect was proposed tomore » explain the ordering and orientation of the intra-wire mesostructure. Circular and spiral nanostructures were found only in wires formed in AAO substrate, not in EPC. Pore-size differences and distinctive wall morphologies of the nanowires relating to the substrates were discussed. It was shown that the material and channel wall characteristics of different substrates play key roles in the ordering and morphology of the intra-wire nanostructures.« less

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

    NASA Astrophysics Data System (ADS)

    Duan, Huimei; Xu, Caixia

    2016-06-01

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

  16. Substrate effect on nanoporous structure of silica wires by channel-confined self-assembly of block-copolymer and sol-gel precursors

    SciTech Connect

    Hu, Michael Z.; Lai, Peng

    2015-09-22

    Nanoporous silica wires of various wire diameters were developed by space-confined molecular self-assembly of triblock copolymer ethylene/propylene/ethylene (P123) and silica alkoxide precursor (tetraethylorthosilicate, TEOS). Two distinctive hard-templating substrates, anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC), with channel diameters in the range between 10 nm and 200 nm were employed for space-confinement of soft molecular self-assembly driven by the block-copolymer microphase separation. It was observed in the scanning and transmission electron microscope (STEM) studies that the substrate geometry and material characteristics had pronounced effects on the structure and morphology of the silica nanowires. A substrate wall effect was proposed to explain the ordering and orientation of the intra-wire mesostructure. Circular and spiral nanostructures were found only in wires formed in AAO substrate, not in EPC. Pore-size differences and distinctive wall morphologies of the nanowires relating to the substrates were discussed. It was shown that the material and channel wall characteristics of different substrates play key roles in the ordering and morphology of the intra-wire nanostructures.

  17. Nanopores: A journey towards DNA sequencing

    PubMed Central

    Wanunu, Meni

    2013-01-01

    Much more than ever, nucleic acids are recognized as key building blocks in many of life's processes, and the science of studying these molecular wonders at the single-molecule level is thriving. A new method of doing so has been introduced in the mid 1990's. This method is exceedingly simple: a nanoscale pore that spans across an impermeable thin membrane is placed between two chambers that contain an electrolyte, and voltage is applied across the membrane using two electrodes. These conditions lead to a steady stream of ion flow across the pore. Nucleic acid molecules in solution can be driven through the pore, and structural features of the biomolecules are observed as measurable changes in the trans-membrane ion current. In essence, a nanopore is a high-throughput ion microscope and a single-molecule force apparatus. Nanopores are taking center stage as a tool that promises to read a DNA sequence, and this promise has resulted in overwhelming academic, industrial, and national interest. Regardless of the fate of future nanopore applications, in the process of this 16-year-long exploration, many studies have validated the indispensability of nanopores in the toolkit of single-molecule biophysics. This review surveys past and current studies related to nucleic acid biophysics, and will hopefully provoke a discussion of immediate and future prospects for the field. PMID:22658507

  18. 3D Nanoporous Metal Phosphides toward High-Efficiency Electrochemical Hydrogen Production.

    PubMed

    Tan, Yongwen; Wang, Hao; Liu, Pan; Cheng, Chun; Zhu, Fan; Hirata, Akihiko; Chen, Mingwei

    2016-04-01

    Free-standing nanoporous metal phosphides are fabricated by a novel top-down method, by selectively leaching less-stable metal phases from rapidly solidified two-phase metal-phosphorus alloys. The phosphide phases with relatively high electrochemical stability are left as the skeletons of nanoporous structures. The resultant nanoporous phosphides with tunable pore size and porosity show superior catalytic activities toward electrochemical hydrogen production. PMID:26889914

  19. Conversion of microwave pyrolysed ASR's char using high temperature agents.

    PubMed

    Donaj, Pawel; Blasiak, Wlodzimierz; Yang, Weihong; Forsgren, Christer

    2011-01-15

    Pyrolysis enables to recover metals and organic feedstock from waste conglomerates such as: automotive shredder residue (ASR). ASR as well as its pyrolysis solid products, is a morphologically and chemically varied mixture, containing mineral materials, including hazardous heavy metals. The aim of the work is to generate fundamental knowledge on the conversion of the organic residues of the solid products after ASR's microwave pyrolysis, treated at various temperatures and with two different types of gasifying agent: pure steam or 3% (v/v) of oxygen. The research is conducted using a lab-scale, plug-flow gasifier, with an integrated scale for analysing mass loss changes over time of experiment, serving as macro TG at 950, 850 and 760 °C. The reaction rate of char decomposition was investigated, based on carbon conversion during gasification and pyrolysis stage. It was found in both fractions that char conversion rate decreases with the rise of external gas temperature, regardless of the gasifying agent. No significant differences between the reaction rates undergoing with steam and oxygen for char decomposition has been observed. This abnormal char behaviour might have been caused by the inhibiting effects of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating. PMID:20940079

  20. Developing scaling relations for the yield strength of nanoporous gold

    NASA Astrophysics Data System (ADS)

    Briot, Nicolas J.; Balk, T. John

    2015-09-01

    In this work, the applicability of Gibson and Ashby's porous scaling relations to nanoporous metals is discussed, and an updated equation is proposed for relating the yield strength of nanoporous gold to the yield strength of individual gold ligaments that form the porous structure. This new relation is derived from experimental measurements obtained by small-scale tensile testing and by nanoindentation, and incorporates the average ligament diameter. Nanoindentation data, obtained experimentally by the authors as well as reported by others in the literature, are reconciled with tensile test measurements previously reported by the present authors. The values of ligament yield strength calculated with the new scaling relation are found to agree with data reported from mechanical testing of nanowires, and the scaling relation thus represents a bridge between nanowire and nanoporous metal behaviour. In addition, calculations of yield strength for nanoporous gold samples with various ligament size and relative density are consistent with the experimentally determined values.

  1. DNA translocation through graphene nanopores.

    PubMed

    Merchant, Christopher A; Healy, Ken; Wanunu, Meni; Ray, Vishva; Peterman, Neil; Bartel, John; Fischbein, Michael D; Venta, Kimberly; Luo, Zhengtang; Johnson, A T Charlie; Drndić, Marija

    2010-08-11

    We report on DNA translocations through nanopores created in graphene membranes. 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, we observe larger blocked currents than for traditional solid-state nanopores. However, ionic current noise levels are several orders of magnitude larger than those for silicon nitride nanopores. These fluctuations are reduced with the atomic-layer deposition of 5 nm of titanium dioxide over the device. Unlike traditional solid-state nanopore materials that are insulating, graphene is an excellent electrical conductor. Use of graphene as a membrane material opens the door to a new class of nanopore devices in which electronic sensing and control are performed directly at the pore. PMID:20698604

  2. Na⁺ and K⁺ ion selectivity by size-controlled biomimetic graphene nanopores.

    PubMed

    Kang, Yu; Zhang, Zhisen; Shi, Hui; Zhang, Junqiao; Liang, Lijun; Wang, Qi; Ågren, Hans; Tu, Yaoquan

    2014-09-21

    Because biological ionic channels play a key role in cellular transport phenomena, they have attracted extensive research interest for the design of biomimetic nanopores with high permeability and selectivity in a variety of technical applications. Inspired by the structure of K(+) channel proteins, we designed a series of oxygen doped graphene nanopores of different sizes by molecular dynamics simulations to discriminate between K(+) and Na(+) channel transport. The results from free energy calculations indicate that the ion selectivity of such biomimetic graphene nanopores can be simply controlled by the size of the nanopore; compared to K(+), the smaller radius of Na(+) leads to a significantly higher free energy barrier in the nanopore of a certain size. Our results suggest that graphene nanopores with a distance of about 3.9 Å between two neighboring oxygen atoms could constitute a promising candidate to obtain excellent ion selectivity for Na(+) and K(+) ions. PMID:25089590

  3. General preparation for Pt-based alloy nanoporous nanoparticles as potential nanocatalysts

    PubMed Central

    Wang, Dingsheng; Zhao, Peng; Li, Yadong

    2011-01-01

    Although Raney nickel made by dealloying has been used as a heterogeneous catalyst in a variety of organic syntheses for more than 80 years, only recently scientists have begun to realize that dealloying can generate nanoporous alloys with extraordinary structural characteristics. Herein, we achieved successful synthesis of a variety of monodisperse alloy nanoporous nanoparticles via a facile chemical dealloying process using nanocrystalline alloys as precursors. The as-prepared alloy nanoporous nanoparticles with large surface area and small pores show superior catalytic properties compared with alloyed nanoparticles. It is believed that these novel alloy nanoporous nanoparticles would open up new opportunities for catalytic applications. PMID:22355556

  4. Single nanopore transport of synthetic and biological polyelectrolytes in three-dimensional hybrid microfluidic/nanofluidic devices

    SciTech Connect

    King, Travis L.; Gatimu, Enid N.; Bohn, Paul W.

    2009-01-02

    This paper presents a study of electrokinetic transport in single nanopores integrated into vertically-stacked three-dimensional hybrid microfluidic/nanofluidic structures. In these devices single nanopores, created by focused ion beam (FIB) milling in thin polymer films, provide fluidic connection between two vertically separated, perpendicular microfluidic channels. Experiments address both systems in which the nanoporous membrane is composed of the same (homojunction) or different (heterojunction) polymer as the microfluidic channels. These devices are then used to study the electrokinetic transport properties of synthetic (i.e., polystyrene sulfonate and polyallylamine) and biological (i.e.,DNA) polyelectrolytes across these nanopores. Single nanopore transport of polyelectrolytes across these nanopores using both electrical current measurements and confocal microscopy. Both optical and electrical measurements indicate that electroosmotic transport is predominant over electrophoresis in single nanopores with d > 180 nm, consistent with results obtained under similar conditions for nanocapillary array membranes.

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

    NASA Astrophysics Data System (ADS)

    Duan, Huimei; Xu, Caixia

    2016-06-01

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

  6. Nanoporous piezo- and ferroelectric thin films.

    PubMed

    Ferreira, Paula; Hou, Ru Z; Wu, Aiying; Willinger, Marc-Georg; Vilarinho, Paula M; Mosa, Jadra; Laberty-Robert, Christel; Boissière, Cédric; Grosso, David; Sanchez, Clément

    2012-02-01

    Nanoporous barium titanate and lead titanate thin films (∼100 nm calculated from ellipsometric data) are prepared starting from sol-gel solutions modified with a commercially available block-copolymer and evaporation-induced self-assembly methodology. The tuning of the thermal treatment followed by in situ ellipsometry allows the decomposition of the organic components and of the structuring agent leading to the formation of porous tetragonal crystalline perovskite structures as observed by XRD, HRTEM, SEM, and ellipsoporosimetry. Both nanoporous barium titanate and lead titanate thin films present local piezoelectric and ferroelectric behavior measured by piezoresponse force microscopy (PFM), being promising platforms for the preparation of the generation of new multifunctional systems. PMID:22206407

  7. Structure of low-density nanoporous dielectrics revealed by low-vacuum electron microscopy and small-angle x-ray scattering

    SciTech Connect

    Kucheyev, S O; Toth, M; Baumann, T F; Hamza, A V; Ilavsky, J; Knowles, W R; Thiel, B L; Tileli, V; van Buuren, T; Wang, Y M; Willey, T M

    2006-06-05

    We use low-vacuum scanning electron microscopy to image directly the ligament and pore size and shape distributions of representative aerogels over a wide range of length scales ({approx} 10{sup 0}-10{sup 5} nm). The images are used for unambiguous, real-space interpretation of small-angle scattering data for these complex nanoporous systems.

  8. Current oscillations in nanopores

    NASA Astrophysics Data System (ADS)

    Hyland, Brittany

    We develop a simple phenomenological model to describe current oscillations in single, conically shaped nanopores. The model utilizes aspects of reaction rate theory, electrochemical oscillators, and nonlinear dynamical systems. Time series of experimental data were analyzed and compared to time series simulated using the model equations. There is good qualitative agreement between experiment and simulation, though the model needs to be improved in order to obtain better quantitative agreement.

  9. Role of sp3 Defect in Ordered Nanoporous Carbon

    NASA Astrophysics Data System (ADS)

    Xu, Enshi; Lueking, Angela; Crespi, Vincent; Lammert, Paul; Maleski, Kathleen

    Schwarzite is considered an ideal model for nanoporous carbon and is energetically more stable than fullerene. However, carbon don't form well-ordered Schwarzite-type nanoporous material possibly due to kinetic arrests under pyrolytic conditions. We computationally discovered a new thermodynamically stable local defect in carbon sp2 networks: an sp3 carbon defect, which inspires new solutions to the problem. The defect is most stable in nanoporous carbon (i.e., networks with negative curvatures, known as Schwarzites) and its topological merit, carrying negative curvature, results in the design of new model structures of nanoporous materials (periodic, negatively-curved networks), and provides a handle of the negative curvature carrier in nanoporous carbon, and we propose a kinetics-dominated synthetic route to novel nanoporous carbon with long range order by controlling the sp3 defect through sp3 carbon atom injection or Si atom substitution, with the aid of first principle molecular dynamics simulation. Calculations also suggest the defect can be observed by Raman.

  10. Nanoporous gold for enzyme immobilization.

    PubMed

    Stine, Keith J; Jefferson, Kenise; Shulga, Olga V

    2011-01-01

    Nanoporous gold (NPG) is a material of emerging interest for immobilization of biomolecules and -especially enzymes. NPG materials provide a high gold surface area onto which biomolecules can either be directly physisorbed or covalently linked after first modifying the NPG with a self-assembled monolayer. The material can be used as a high surface area electrode and with immobilized enzymes can be used for amperometric detection schemes. NPG can be prepared in a variety of formats from alloys containing less than 50 atomic% gold by dealloying procedures. Related high surface area gold structures have been prepared using templating approaches. Covalent enzyme immobilization can be achieved by first forming a self-assembled monolayer on NPG bearing a terminal reactive functional group followed by conjugation to the enzyme through amide linkages to lysine residues. PMID:20865389

  11. Quantized ionic conductance in nanopores

    SciTech Connect

    Zwolak, Michael; Lagerqvist, Johan; Di Ventra, Massimilliano

    2009-01-01

    Ionic transport in nanopores is a fundamentally and technologically important problem in view of its ubiquitous occurrence in biological processes and its impact on DNA sequencing applications. Using microscopic calculations, we show that ion transport may exhibit strong non-liDearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. Once in the pore, the water molecules form wavelike structures due to multiple scattering at the surface of the pore walls and interference with the radial waves around the ion. We discuss these effects as well as the conditions under which the step-like features in the ionic conductance should be experimentally observable.

  12. Controlling interfacial curvature in nanoporous silica films formed by evaporation-induced self-assembly from nonionic surfactants. II. Effect of processing parameters on film structure.

    PubMed

    Urade, Vikrant N; Bollmann, Luis; Kowalski, Jonathan D; Tate, Michael P; Hillhouse, Hugh W

    2007-04-10

    The double-gyroid phase of nanoporous silica films has been shown to possess facile mass-transport properties and may be used as a mold to fabricate a variety of highly ordered inverse double-gyroid metal and semiconductor films. This phase exists only over a very small region of the binary phase diagram for most surfactants, and it has been very difficult to synthesize metal oxide films with this structure by evaporation-induced self-assembly (EISA). Here, we show the interplay of the key parameters needed to synthesize these structures reproducibly and show that the interfacial curvature may be systematically controlled. Grazing angle of incidence small-angle X-ray scattering (GISAXS) is used to determine the structure and orientation of nanostructured silica films formed by EISA from dilute silica/(poly(ethylene oxide)-b-poly(propylene oxide)-b-alkyl) surfactant solutions. Four different highly ordered film structures are observed by changing only the concentration of the surfactant, the relative humidity during dip-coating, and the aging time of the solution prior to coating. The highly ordered films progress from rhombohedral (Rm) to 2D rectangular (c2m) to double-gyroid (distorted Iad) to lamellar systematically as interfacial curvature decreases. Under all experimental conditions investigated, increasing the aging time of the coating solution was found to decrease the interfacial curvature. In particular, this parameter was critical to being able to synthesize highly ordered, pure-phase double-gyroid films. The key role of the aging time is shown via processing diagrams that map out the interplay between the aging time, composition, and relative humidity. 29Si nuclear magnetic resonance (NMR) spectroscopy and solution-phase small-angle X-ray scattering (SAXS) of the aged coating solutions presented in part I of this series are then used to interpret the effects of aging prior to dip-coating. Specifically, it was found that a predictive model based on volume

  13. Effects of Heat Flux, Oxygen Concentration and Glass Fiber Volume Fraction on Pyrolysate Mass Flux from Composite Solids

    NASA Technical Reports Server (NTRS)

    Rich, D. B.; Lautenberger, C. W.; Yuan, Z.; Fernandez-Pello, A. C.

    2004-01-01

    Experimental work on the effects of heat flux, oxygen concentration and glass fiber volume fraction on pyrolysate mass flux from samples of polypropylene/glass fiber composite (PP/G) is underway. The research is conducted as part of a larger project to develop a test methodology for flammability of materials, particularly composites, in the microgravity and variable oxygen concentration environment of spacecraft and space structures. Samples of PP/G sized at 30 x 30 x 10 mm are flush mounted in a flow tunnel, which provides a flow of oxidizer over the surface of the samples at a fixed value of 1 m/s and oxygen concentrations varying between 18 and 30%. Each sample is exposed to a constant external radiant heat flux at a given value, which varies between tests from 10 to 24 kW/sq m. Continuous sample mass loss and surface temperature measurements are recorded for each test. Some tests are conducted with an igniter and some are not. In the former case, the research goal is to quantify the critical mass flux at ignition for the various environmental and material conditions described above. The later case generates a wider range of mass flux rates than those seen prior to ignition, providing an opportunity to examine the protective effects of blowing on oxidative pyrolysis and heating of the surface. Graphs of surface temperature and sample mass loss vs. time for samples of 30% PPG at oxygen concentrations of 18 and 21% are presented in the figures below. These figures give a clear indication of the lower pyrolysis rate and extended time to ignition that accompany a lower oxygen concentration. Analysis of the mass flux rate at the time of ignition gives good repeatability but requires further work to provide a clear indication of mass flux trends accompanying changes in environmental and material properties.

  14. Effects of Heat Flux, Oxygen Concentration and Glass Fiber Volume Fraction on Pyrolysate Mass Flux from Composite Solids

    NASA Technical Reports Server (NTRS)

    Rich, D. B.; Lautenberger, C. W.; Yuan, Z.; Fernandez-Pello, A. C.

    2004-01-01

    Experimental work on the effects of heat flux, oxygen concentration and glass fiber volume fraction on pyrolysate mass flux from samples of polypropylene/glass fiber composite (PP/G) is underway. The research is conducted as part of a larger project to develop a test methodology for flammability of materials, particularly composites, in the microgravity and variable oxygen concentration environment of spacecraft and space structures. Samples of PP/G sized at 30x30x10 mm are flush mounted in a flow tunnel, which provides a flow of oxidizer over the surface of the samples at a fixed value of 1 m/s and oxygen concentrations varying between 18 and 30%. Each sample is exposed to a constant external radiant heat flux at a given value, which varies between tests from 10 to 24 kW/m2. Continuous sample mass loss and surface temperature measurements are recorded for each test. Some tests are conducted with an igniter and some are not. In the former case, the research goal is to quantify the critical mass flux at ignition for the various environmental and material conditions described above. The later case generates a wider range of mass flux rates than those seen prior to ignition, providing an opportunity to examine the protective effects of blowing on oxidative pyrolysis and heating of the surface. Graphs of surface temperature and sample mass loss vs. time for samples of 30% PPG at oxygen concentrations of 18 and 21% are presented in the figures below. These figures give a clear indication of the lower pyrolysis rate and extended time to ignition that accompany a lower oxygen concentration. Analysis of the mass flux rate at the time of ignition gives good repeatability but requires further work to provide a clear indication of mass flux trends accompanying changes in environmental and material properties.

  15. A new technique to pyrolyse biomass in a microwave system: effect of stirrer speed.

    PubMed

    Abubakar, Zubairu; Salema, Arshad Adam; Ani, Farid Nasir

    2013-01-01

    A new technique to pyrolyse biomass in microwave (MW) system is presented in this paper to solve the problem of bio-oil deposition. Pyrolysis of oil palm shell (OPS) biomass was conducted in 800 W and 2.45 GHz frequency MW system using an activated carbon as a MW absorber. The temperature profile, product yield and the properties of the products were found to depend on the stirrer speed and MW absorber percentage. The highest bio-oil yield of 28 wt.% was obtained at 25% MW absorber and 50 rpm stirrer speed. Bio-char showed highest calorific value of the 29.5 MJ/kg at 50% MW absorber and 100 rpm stirrer speed. Bio-oil from this study was rich in phenol with highest detected as 85 area% from the GC-MS results. Thus, OPS bio-oil can become potential alternative to petroleum-based chemicals in various phenolic based applications. PMID:23211483

  16. Lipid accumulation from pinewood pyrolysates by Rhodosporidium diobovatum and Chlorella vulgaris for biodiesel production.

    PubMed

    Luque, Luis; Orr, Valerie C A; Chen, Sean; Westerhof, Roel; Oudenhoven, Stijn; Rossum, Guus van; Kersten, Sascha; Berruti, Franco; Rehmann, Lars

    2016-08-01

    This study evaluated the suitability of pinewood pyrolysates as a carbon source for lipid production and cultivation of the oleaginous yeast Rhodosporidium diobovatum and the microalgae Chlorella vulgaris. Thermal decomposition of pinewood and fractional condensation were used to obtain an oil rich in levoglucosan which was upgraded to glucose by acid hydrolysis. Blending of pyrolytic sugars with pure glucose in both nitrogen rich and nitrogen limited conditions was studied for R. diobovatum, and under nitrogen limited conditions for C. vulgaris. Glucose consumption rate decreased with increasing proportions of pyrolytic sugars increasing cultivation time. While R. diobovatum was capable of growth in 100% (v/v) pyrolytic sugars, C. vulgaris growth declined rapidly in blends greater than 20% (v/v) until no growth was detected in blends >40%. Finally, the effects of pyrolysis sugars on lipid composition was evaluated and biodiesel fuel properties were estimated based on the lipid profiles. PMID:27208736

  17. Study on small molecular organic compounds pyrolysed from rubber seed oil and its sodium soap.

    PubMed

    Fernando, T L D; Prashantha, M A B; Amarasinghe, A D U S

    2016-01-01

    Rubber seed oil (RSO) and its sodium soap were pyrolysed in a batch reactor to obtain low molar mass organic substances. The pyrolitic oil of RSO was redistilled and the distillates were characterized by GC-MS and FTIR. Density, acid value, saponification value and ester values were also measured according to the ASTM standard methods. A similar analysis was done for samples taken out at different time intervals from the reaction mixture. Industrially important low molar mass alkanes, alkenes, aromatics, cyclic compounds and carboxylic acids were identified in the pyrolysis process of rubber seed oil. However, pyrolysis of the sodium soap of rubber seed oil gave a mixture of hydrocarbons in the range of C14-C17 and hence it has more applications as a fuel. PMID:27066350

  18. Large enhancement of quantum dot fluorescence by highly scalable nanoporous gold.

    PubMed

    Zhang, Ling; Song, Yunke; Fujita, Takeshi; Zhang, Ye; Chen, Mingwei; Wang, Tza-Huei

    2014-02-26

    Dealloyed nanoporous gold (NPG) dramatically enhances quantum dot (QD) fluorescence by amplifying near-field excitation and increasing the radiative decay rate. Originating from plasmonic coupling, the fluorescence enhancement is highly dependent upon the nanopore size of the NPG. In contrast to other nanoengineered metallic structures, NPG exhibits fluorescence enhancement of QDs over a large substrate surface. PMID:24339211

  19. The evolution of nanopore sequencing.

    PubMed

    Wang, Yue; Yang, Qiuping; Wang, Zhimin

    2014-01-01

    The "$1000 Genome" project has been drawing increasing attention since its launch a decade ago. Nanopore sequencing, the third-generation, is believed to be one of the most promising sequencing technologies to reach four gold standards set for the "$1000 Genome" while the second-generation sequencing technologies are bringing about a revolution in life sciences, particularly in genome sequencing-based personalized medicine. Both of protein and solid-state nanopores have been extensively investigated for a series of issues, from detection of ionic current blockage to field-effect-transistor (FET) sensors. A newly released protein nanopore sequencer has shown encouraging potential that nanopore sequencing will ultimately fulfill the gold standards. In this review, we address advances, challenges, and possible solutions of nanopore sequencing according to these standards. PMID:25610451

  20. The evolution of nanopore sequencing

    PubMed Central

    Wang, Yue; Yang, Qiuping; Wang, Zhimin

    2014-01-01

    The “$1000 Genome” project has been drawing increasing attention since its launch a decade ago. Nanopore sequencing, the third-generation, is believed to be one of the most promising sequencing technologies to reach four gold standards set for the “$1000 Genome” while the second-generation sequencing technologies are bringing about a revolution in life sciences, particularly in genome sequencing-based personalized medicine. Both of protein and solid-state nanopores have been extensively investigated for a series of issues, from detection of ionic current blockage to field-effect-transistor (FET) sensors. A newly released protein nanopore sequencer has shown encouraging potential that nanopore sequencing will ultimately fulfill the gold standards. In this review, we address advances, challenges, and possible solutions of nanopore sequencing according to these standards. PMID:25610451

  1. Multilayer hexagonal silicon forming in slit nanopore

    PubMed Central

    He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

    2015-01-01

    The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties. PMID:26435518

  2. Multilayer hexagonal silicon forming in slit nanopore.

    PubMed

    He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

    2015-01-01

    The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties. PMID:26435518

  3. Formation of nanoporous aerogels from wheat starch.

    PubMed

    Ubeyitogullari, Ali; Ciftci, Ozan N

    2016-08-20

    Biodegradable nanoporous aerogels were obtained from wheat starch using a simple and green method based on supercritical carbon dioxide (SC-CO2) drying. Effects of processing parameters (temperature, wheat starch concentration and mixing rate during gelatinization; temperature, pressure, and flow rate of CO2, during SC-CO2 drying) on the aerogel formation were investigated, and optimized for the highest surface area and smallest pore size of the aerogels. At the optimized conditions, wheat starch aerogels had surface areas between 52.6-59.7m(2)/g and densities ranging between 0.05-0.29g/cm(3). The average pore size of the starch aerogels was 20nm. Starch aerogels were stable up to 280°C. Due to high surface area and nanoporous structure, wheat starch aerogels are promising carrier systems for bioactives and drugs in food and pharmaceutical industries. PMID:27178916

  4. Sulfonated nanoporous colloidal films and membranes

    NASA Astrophysics Data System (ADS)

    Smith, Joanna Jane

    The objective of this thesis is to describe the preparation and investigation of a new class of proton-conducting membrane materials, namely, nanoporous colloidal membranes whose proton conductivity results from the nanopore surface modification with organic molecules carrying acid functionalities. Both the proton transport and ion transport were studied in nanoporous silica colloidal crystals that were surface modified with sulfonic groups. First, the transport of ions was studied through sulfonated silica colloidal films that were supported on platinum electrodes using cyclic voltammetry. The surface of self-assembled nanoporous silica colloidal crystalline films was sulfonated using 1,3-propanesultone. We found that the flux of anions through the sulfonated colloidal films is reduced, while the flux of cations is increased, compared to the unmodified colloidal films. Second, the proton transport in free-standing assemblies of surface-sulfonated silica nanospheres, either randomly packed or self-assembled into a close-packed arrangement, were studied. It was demonstrated that colloidal assemblies prepared using surface-sulfonated silica nanospheres posses proton conductivity that depends on the ordering of the material, temperature and relative humidity. Based on the comparison between the close-packed and disordered assemblies made of the same spheres, we conclude that the increase in structural organization of the self-assembled colloidal materials leads to increased proton conductivity and better water retention. Next free-standing colloidal membranes with a relatively large area and no mechanical defects were prepared by sintering silica colloidal films. The sintered membranes were then surface rehydroxylated, which restores the surface silanol groups, and then can be chemically modified. Finally, sintered self-assembled nanoporous silica colloidal crystals were modified with poly(sulfopropyl-methacrylate) (pSPM) and poly(stryrenesulfonic acid) (pSSA) brushes

  5. Influence of Structural Heterogeneity on Diffusion of CH4 and CO2 in Silicon Carbide-Derived Nanoporous Carbon

    PubMed Central

    2015-01-01

    We investigate the influence of structural heterogeneity on the transport properties of simple gases in a Hybrid Reverse Monte Carlo (HRMC) constructed model of silicon carbide-derived carbon (SiC-DC). The energy landscape of the system is determined based on free energy analysis of the atomistic model. The overall energy barriers of the system for different gases are computed along with important properties, such as Henry constant and differential enthalpy of adsorption at infinite dilution, and indicate hydrophobicity of the SiC-DC structure and its affinity for CO2 and CH4 adsorption. We also study the effect of molecular geometry, pore structure and energy heterogeneity considering different hopping scenarios for diffusion of CO2 and CH4 through ultramicropores using the Nudged Elastic Band (NEB) method. It is shown that the energy barrier of a hopping molecule is very sensitive to the shape of the pore entry. We provide evidence for the influence of structural heterogeneity on self-diffusivity of methane and carbon dioxide using molecular dynamics simulation, based on a maximum in the variation of self-diffusivity with loading. A comparison of the MD simulation results with self-diffusivities from quasi-elastic neutron scattering (QENS) measurements and, with macroscopic uptake-based low-density transport coefficients, reveals the existence of internal barriers not captured in MD simulation and QENS experiments. Nevertheless, the simulation and macroscopic uptake-based diffusion coefficients agree within a factor of 2–3, indicating that our HRMC model structure captures most of the important energy barriers affecting the transport of CH4 in the nanostructure of SiC-DC. PMID:24932319

  6. Fluid Behavior and Fluid-Solid Interactions in Nanoporous Media

    NASA Astrophysics Data System (ADS)

    Xu, H.

    2015-12-01

    Although shale oil/gas production in the US has increased exponentially, the low energy recovery is a daunting problem needed to be solved for its sustainability and continued growth, especially in light of the recent oil/gas price decline. This is apparently related to the small porosity (a few to a few hundred nm) and low permeability (10-16-10-20 m2) of tight shale formations. The fundamental question lies in the anomalous behavior of fluids in nanopores due to confinement effects, which, however, remains poorly understood. In this study, we combined experimental characterization and observations, particularly using small-angle neutron scattering (SANS), with pore-scale modeling using lattice Boltzmann method (LBM), to examine the fluid behavior and fluid-solid interactions in nanopores at reservoir conditions. Experimentally, we characterized the compositions and microstructures of a shale sample from Wolfcamp, Texas, using a variety of analytical techniques. Our analyses reveal that the shale sample is made of organic-matter (OM)-lean and OM-rich layers that exhibit different chemical and mineral compositions, and microstructural characteristics. Using the hydrostatic pressure system and gas-mixing setup we developed, in-situ SANS measurements were conducted at pressures up to 20 kpsi on shale samples imbibed with water or water-methane solutions. The obtained results indicate that capillary effect plays a significant role in fluid-nanopore interactions and the associated changes in nanopore structures vary with pore size and pressure. Computationally, we performed LBM modeling to simulate the flow behavior of methane in kerogen nanoporous structure. The correction factor, which is the ratio of apparent permeability to intrinsic permeability, was calculated. Our results show that the correction factor is always greater than one (non-continuum/non-Darcy effects) and increases with decreasing nanopore size, intrinsic permeability and pressure. Hence, the

  7. Protein conducting nanopores

    NASA Astrophysics Data System (ADS)

    Harsman, Anke; Krüger, Vivien; Bartsch, Philipp; Honigmann, Alf; Schmidt, Oliver; Rao, Sanjana; Meisinger, Christof; Wagner, Richard

    2010-11-01

    About 50% of the cellular proteins have to be transported into or across cellular membranes. This transport is an essential step in the protein biosynthesis. In eukaryotic cells secretory proteins are transported into the endoplasmic reticulum before they are transported in vesicles to the plasma membrane. Almost all proteins of the endosymbiotic organelles chloroplasts and mitochondria are synthesized on cytosolic ribosomes and posttranslationally imported. Genetic, biochemical and biophysical approaches led to rather detailed knowledge on the composition of the translocon-complexes which catalyze the membrane transport of the preproteins. Comprehensive concepts on the targeting and membrane transport of polypeptides emerged, however little detail on the molecular nature and mechanisms of the protein translocation channels comprising nanopores has been achieved. In this paper we will highlight recent developments of the diverse protein translocation systems and focus particularly on the common biophysical properties and functions of the protein conducting nanopores. We also provide a first analysis of the interaction between the genuine protein conducting nanopore Tom40SC as well as a mutant Tom40SC (\\mathrm {S}_{54} \\to E ) containing an additional negative charge at the channel vestibule and one of its native substrates, CoxIV, a mitochondrial targeting peptide. The polypeptide induced a voltage-dependent increase in the frequency of channel closure of Tom40SC corresponding to a voltage-dependent association rate, which was even more pronounced for the Tom40SC S54E mutant. The corresponding dwelltime reflecting association/transport of the peptide could be determined with \\bar {t}_{\\mathrm {off}} \\cong 1.1 ms for the wildtype, whereas the mutant Tom40SC S54E displayed a biphasic dwelltime distribution (\\bar {t}_{\\mathrm {off}}^1 \\cong 0.4 ms \\bar {t}_{\\mathrm {off}}^2 \\cong 4.6 ms).

  8. Synthesis and electronic structure of low-density monoliths of nanoporous nanocrystalline anatase TiO2

    SciTech Connect

    Kucheyev, S O; Baumann, T F; Wang, Y M; van Buuren, T; Satcher, J H

    2004-08-13

    Monolithic nanocrystalline anatase titania aerogels are synthesized by the epoxide sol-gel method followed by thermal annealing at 550 C. These aerogels are formed by {approx}10-20 nm size anatase nanoparticles which are randomly oriented and interconnected into an open-cell solid network. Aerogel monoliths have an apparent density of {approx}6% and a surface area of {approx} 100 m{sup 2} g{sup -1}. High-resolution transmission electron microscopy and soft x-ray absorption near-edge structure spectroscopy reveal good crystallinity of the anatase nanoparticles forming the aerogel skeleton.

  9. Highly efficient shrinkage of inverted-pyramid silicon nanopores by plasma-enhanced chemical vapor deposition technology.

    PubMed

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

    2016-06-24

    Solid-state nanopore-based analysis systems are currently one of the most attractive and promising platforms in sensing fields. This work presents a highly efficient method to shrink inverted-pyramid silicon nanopores using plasma-enhanced chemical vapor deposition (PECVD) technology by the deposition of SiN x onto the surface of the nanopore. The contraction of the inverted-pyramid silicon nanopores when subjected to the PECVD process has been modeled and carefully analyzed, and the modeling data are in good agreement with the experimental results within a specific PECVD shrinkage period (∼0-600 s). Silicon nanopores within a 50-400 nm size range contract to sub-10 nm dimensions. Additionally, the inner structure of the nanopores after the PECVD process has been analyzed by focused ion beam cutting process. The results show an inner structure morphology change from inverted-pyramid to hourglass, which may enhance the spatial resolution of sensing devices. PMID:27181294

  10. Highly efficient shrinkage of inverted-pyramid silicon nanopores by plasma-enhanced chemical vapor deposition technology

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Solid-state nanopore-based analysis systems are currently one of the most attractive and promising platforms in sensing fields. This work presents a highly efficient method to shrink inverted-pyramid silicon nanopores using plasma-enhanced chemical vapor deposition (PECVD) technology by the deposition of SiN x onto the surface of the nanopore. The contraction of the inverted-pyramid silicon nanopores when subjected to the PECVD process has been modeled and carefully analyzed, and the modeling data are in good agreement with the experimental results within a specific PECVD shrinkage period (∼0–600 s). Silicon nanopores within a 50–400 nm size range contract to sub-10 nm dimensions. Additionally, the inner structure of the nanopores after the PECVD process has been analyzed by focused ion beam cutting process. The results show an inner structure morphology change from inverted-pyramid to hourglass, which may enhance the spatial resolution of sensing devices.

  11. Molecular Sensing by Nanoporous Crystalline Polymers

    PubMed Central

    Pilla, Pierluigi; Cusano, Andrea; Cutolo, Antonello; Giordano, Michele; Mensitieri, Giuseppe; Rizzo, Paola; Sanguigno, Luigi; Venditto, Vincenzo; Guerra, Gaetano

    2009-01-01

    Chemical sensors are generally based on the integration of suitable sensitive layers and transducing mechanisms. Although inorganic porous materials can be effective, there is significant interest in the use of polymeric materials because of their easy fabrication process, lower costs and mechanical flexibility. However, porous polymeric absorbents are generally amorphous and hence present poor molecular selectivity and undesired changes of mechanical properties as a consequence of large analyte uptake. In this contribution the structure, properties and some possible applications of sensing polymeric films based on nanoporous crystalline phases, which exhibit all identical nanopores, will be reviewed. The main advantages of crystalline nanoporous polymeric materials with respect to their amorphous counterparts are, besides a higher selectivity, the ability to maintain their physical state as well as geometry, even after large guest uptake (up to 10–15 wt%), and the possibility to control guest diffusivity by controlling the orientation of the host polymeric crystalline phase. The final section of the review also describes the ability of suitable polymeric films to act as chirality sensors, i.e., to sense and memorize the presence of non-racemic volatile organic compounds. PMID:22303150

  12. Water adsorption in ion-bearing nanopores.

    PubMed

    Lakatos, G; Patey, G N

    2007-01-14

    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 0.74 nm and containing Na+, K+, Ca2+, Cl-, or F- at 298 K are computed. In all cases the nanopores are found to fill at reservoir chemical potentials below the chemical potential of saturated water vapor at 298 K. 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. PMID:17228962

  13. SMALL-ANGLE NEUTRON SCATTERING CHARACTERIZATION OF THE STRUCTURE OF NANOPOROUS CARBONS FOR ENERGY-RELATED APPLICATIONS

    SciTech Connect

    He, Lilin; Mavila Chathoth, Suresh; Melnichenko, Yuri B; Presser, Volker; Mcdonough, John; Gogotsi, Yury G.

    2011-01-01

    We used small-angle neutron scattering (SANS) and neutron contrast variation to study the structure of four nanoporouscarbons prepared by thermo-chemical etching of titanium carbide TiC in chlorine at 300, 400, 600, and 800 C with pore diameters ranging between -4 and -11 {angstrom}. SANS patterns were obtained from dry samples and samples saturated with deuterium oxide (D{sub 2}O) in order to delineate origin of the power law scattering in the low Q domain as well as to evaluate pore accessibility for D{sub 2}O molecules. SANS cross section of all samples was fitted to Debye-Anderson-Brumberger (DAB), DAB-Kirste-Porod models as well as to the Guinier and modified Guinier formulae for cylindrical objects, which allowed for evaluating the radii of gyration as well as the radii and lengths of the pores under cylindrical shape approximation. SANS data from D{sub 2}O-saturated samples indicate that strong upturn in the low Q limit usually observed in the scattering patterns from microporous carbon powders is due to the scattering from outer surface of the powder particles. Micropores are only partially filled with D{sub 2}O molecules due to geometrical constraints and or partial hydrophobicity of the carbon matrix. Structural parameters of the dry carbons obtained using SANS are compared with the results of the gas sorption measurements and the values agree for carbide-derived carbons (CDCs) obtained at high chlorination temperatures (>600 C). For lower chlorination temperatures, pore radii obtained from gas sorption overestimate the actual pore size as calculated from SANS for two reasons: inaccessible small pores are present and the model-dependent fitting based on density functional theory models assumes non-spherical pores, whereas SANS clearly indicates that the pore shape in microporous CDC obtained at low chlorination temperatures is nearly spherical.

  14. Localized functionalization of single nanopores

    SciTech Connect

    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.

  15. Development of macroscopic nanoporous graphene membranes for gas separation

    NASA Astrophysics Data System (ADS)

    Boutilier, Michael; Hadjiconstantinou, Nicolas; Karnik, Rohit

    2015-11-01

    Nanoporous graphene membranes have the potential to exceed permeance and selectivity limits of existing gas separation membranes due to their atomic thickness and ability to support sub-nanometer pores for molecular sieving, while offering low resistance to flow. Gas separation by graphene nanopores has been demonstrated experimentally on micron-scale membranes, but scaling-up to larger sizes is challenging due to graphene imperfections and control of the selective nanopore size distribution. Using a model we developed for the inherent permeance of graphene, we designed a macroscopic graphene membrane predicted to be selectively permeable despite material imperfections. Micrometer-scale defects are sealed by interfacial polymerization and nanometer-scale defects are sealed by atomic layer deposition. The underlying support structure is tuned to further reduce the effects of leakage. Finally, ion bombardment followed by oxidative etching is used to create a high density of selective nanopores. SEM and TEM imaging are used to characterize the resulting membrane structure, and its performance is assessed by gas permeance and selectivity measurements. This work provides insight into gas flow through nanoporous graphene membranes and guides their future development.

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

    PubMed

    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

  17. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J.; Hryn, John N.; Elam, Jeffrey W.

    2009-12-01

    A nanoporous catalytic membrane which displays several unique features including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity.

  18. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  19. Deformation mechanisms in gold nanowires and nanoporous gold

    NASA Astrophysics Data System (ADS)

    Dou, R.; Derby, B.

    2011-03-01

    We present a study of the deformation of gold nanowires of diameter 30-70 nm and nanoporous gold specimens with ligament diameter 5-10 nm, both produced by electrodeposition into anodised aluminium oxide templates. The nanowires show extensive surface slip steps and low dislocation densities with a few perfect dislocation loops, Shockley partial dislocations and microtwins observed after deformation. Nanoporous specimens show deformation localised to the nodes between the ligaments of the foamed structure, with high densities of microtwins and Shockley partial dislocations in these regions. Similar dislocation structures are seen in larger nanowires deformed in bending. This is shown to be consistent with a strain gradient plasticity model for the deformation of nanoporous gold, with the strain gradient accommodated by geometrically necessary twins and partial dislocations.

  20. Multistep current signal in protein translocation through graphene nanopores.

    PubMed

    Bonome, Emma Letizia; Lepore, Rosalba; Raimondo, Domenico; Cecconi, Fabio; Tramontano, Anna; Chinappi, Mauro

    2015-05-01

    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. PMID:25866995

  1. Lensless imaging of nanoporous glass with soft X-rays

    DOE PAGESBeta

    Turner, Joshua J.; Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; Jacobsen, Chris

    2013-06-01

    Coherent soft X-ray diffraction has been used to image nanoporous glass structure in two dimensions using different methods. The merit of the reconstructions was judged using a new method of Fourier phase correlation with a final, refined image. The porous structure was found to have a much larger average size then previously believed.

  2. Synthesis and characterization of nanoporous silica film via non-surfactant template sol-gel technique

    NASA Astrophysics Data System (ADS)

    Al-Harbi, T.; Al-Hazmi, F.; Mahmoud, Waleed E.

    2012-10-01

    Nanoporous silicon dioxide has received growing interests owing to their peculiar application potentials in conservation and storage energy. Therefore, the development of novel and simple techniques is required for raising these nanoporous materials to industrial level. In this research, we report novel strategy for the synthesis of nanoporous SiO2 via non-surfactant template sol-gel technique for the first time. The morphology and structure of the as prepared and annealed nanoporous silica films were studied using X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy and nitrogen absorption/desorption technique. The results showed that highly order nanoporous silica film has been obtained at annealing temperature 600 °C with average diameter 5.1 nm and average pore volume 3.6 cm3 g-1.

  3. Fabrication of high reflectivity nanoporous distributed Bragg reflectors by controlled electrochemical etching of GaN

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Min; Kang, Jin-Ho; Lee, June Key; Ryu, Sang-Wan

    2016-07-01

    The nanoporous medium is a valuable feature of optical devices because of its variable optical refractive index with porosity. One important application is in a GaN-based vertical cavity surface emitting laser having a distributed Bragg reflector (DBR) composed of alternating nanoporous and bulk GaNs. However, optimization of the fabrication process for high reflectivity DBRs having wellcontrolled high reflection bands has not been studied yet. We used electrochemical etching to study the fabrication process of a nanoporous GaN DBR and analyzed the relationship between the morphology and optical reflectivity. Several electrolytes were examined for the formation of the optimized nanoporous structure. A highly reflective DBRs having reflectivity of ~100% were obtained over a wide wavelength range of 450-750 nm. Porosification of semiconductors into nanoporous layers could provide a high reflectivity DBR due to controlled index-contrast, which would be advantages for the construction of a high-Q optical cavity.

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

    PubMed Central

    2007-01-01

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

  5. Photothermoelectric Effects in Nanoporous Silicon.

    PubMed

    Lai, Yu-Sheng; Tsai, Chao-Yang; Chang, Chin-Kai; Huang, Cheng-Yin; Hsiao, Vincent K S; Su, Yuhlong Oliver

    2016-04-01

    The first observation of the photothermoelectric effect in a nanoporous silicon (NPSi) device indicates that the photocurrent is dependent on the position of light-induced local heating from illumination at the Au-electrode/NPSi interface. PMID:26821828

  6. A novel nanoporous graphitic composite.

    PubMed

    Wang, Zheng-Ming; Hoshinoo, Kumiko; Xue, M; Kanoh, Hirofumi; Ooi, Kenta

    2002-08-21

    A novel nanoporous composite containing micrographitic carbon layers is synthesized by preliminarily expanding the interlayer of an oxidized product of graphite using surfactant, followed by Si bridging/pillaring, and carbonization. PMID:12211211

  7. Characterization of hydrophobic nanoporous particle liquids for energy absorption

    NASA Astrophysics Data System (ADS)

    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. Fabricating Nanodots using Lift-Off of a Nanopore Template

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok; Ramsey, Christopher R.; Bae, Youngsam; Choi, Daniel S.

    2008-01-01

    A process for fabricating a planar array of dots having characteristic dimensions of the order of several nanometers to several hundred nanometers involves the formation and use of a thin alumina nanopore template on a semiconductor substrate. The dot material is deposited in the nanopores, then the template is lifted off the substrate after the dots have been formed. This process is expected to be a basis for development of other, similar nanofabrication processes for relatively inexpensive mass production of nanometerscale optical, optoelectronic, electronic, and magnetic devices. Alumina nanopore templates are self-organized structures that result from anodization of aluminum under appropriate conditions. Alumina nanopore templates have been regarded as attractive for use in fabricating the devices mentioned above, but prior efforts to use alumina nanopore templates for this purpose have not been successful. One reason for the lack of success is that the aspect ratios (ratios between depth and diameter) of the pores have been too large: large aspect ratios can result in blockage of deposition and/or can prevent successful lift-off. The development of the present process was motivated partly by a requirement to reduce aspect ratios to values (of the order of 10) for which there is little or no blockage of deposition and attempts at lift-off are more likely to be successful. The fabrication process is outlined.

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

    SciTech Connect

    Ray, S. J.

    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.

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

    NASA Astrophysics Data System (ADS)

    Ray, S. J.

    2014-12-01

    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.

  11. Single nanopore transport of synthetic and biological polyelectrolytes in three-dimensional hybrid microfluidic/nanofluidic devices

    DOE PAGESBeta

    King, Travis L.; Gatimu, Enid N.; Bohn, Paul W.

    2009-01-02

    This paper presents a study of electrokinetic transport in single nanopores integrated into vertically-stacked three-dimensional hybrid microfluidic/nanofluidic structures. In these devices single nanopores, created by focused ion beam (FIB) milling in thin polymer films, provide fluidic connection between two vertically separated, perpendicular microfluidic channels. Experiments address both systems in which the nanoporous membrane is composed of the same (homojunction) or different (heterojunction) polymer as the microfluidic channels. These devices are then used to study the electrokinetic transport properties of synthetic (i.e., polystyrene sulfonate and polyallylamine) and biological (i.e.,DNA) polyelectrolytes across these nanopores. Single nanopore transport of polyelectrolytes across these nanoporesmore » using both electrical current measurements and confocal microscopy. Both optical and electrical measurements indicate that electroosmotic transport is predominant over electrophoresis in single nanopores with d > 180 nm, consistent with results obtained under similar conditions for nanocapillary array membranes.« less

  12. Nanoporous materials for biomedical devices.

    SciTech Connect

    Adiga, S. P.; Curtiss, L. A.; Elam, J. W.; Pellin, M. J.; Shih, C.-C.; Shin, C.-M.; Lin, S.-J.; Su, Y.-Y.; Gittard, S. D.; Zhang, J.; Narayan, R. J.; National Yang-Ming Univ.; Taipei Medical Univ.; Univ. of North Carolina at Chapel Hill

    2008-01-01

    Nanoporous materials are currently being developed for use in implantable drug delivery systems, bioartificial organs, and other novel medical devices. Advances in nanofabrication have made it possible to precisely control the pore size, pore distribution, porosity, and chemical properties of pores in nanoporous materials. As a result, these materials are attractive for regulating and sensing transport at the molecular level. In this work, the use of nanoporous membranes for biomedical applications is reviewed. The basic concepts underlying membrane transport are presented in the context of design considerations for efficient size sorting. Desirable properties of nanoporous membranes used in implantable devices, including biocompatibility and antibiofouling behavior, are also discussed. In addition, the use of surface modification techniques to improve the function of nanoporous membranes is reviewed. An intriguing possibility involves functionalizing nanoporous materials with smart polymers in order to modulate biomolecular transport in response to pH, temperature, ionic concentration, or other stimuli. These efforts open up avenues to develop smart medical devices that respond to specific physiological conditions.

  13. Photoresistance Switching of Plasmonic Nanopores

    PubMed Central

    2015-01-01

    Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (∼1–2 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification. PMID:25514824

  14. Photoresistance switching of plasmonic nanopores.

    PubMed

    Li, Yi; Nicoli, Francesca; Chen, Chang; Lagae, Liesbet; Groeseneken, Guido; Stakenborg, Tim; Zandbergen, Henny W; Dekker, Cees; Van Dorpe, Pol; Jonsson, Magnus P

    2015-01-14

    Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (∼ 1-2 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification. PMID:25514824

  15. Synthesis and characterization of responsive nanoporous materials

    NASA Astrophysics Data System (ADS)

    Abelow, Alexis Elizabeth

    This thesis describes the synthesis and properties of polymer or oligonucleotide-modified nanoporous membranes and nanopores which exhibit a response to external stimuli, synthesized with the intention of mimicking biological protein channels. The responsiveness of these systems arises as a function of the polymer or oligonucleotide modifier, which exhibit a change in conformation with exposure to temperature, pH, introduction of a small molecule, or electric potential. First, the transport of ions through supported silica colloidal films modified with poly(L-alanine) on platinum electrodes was studied using cyclic voltammetry. By monitoring the flux of a redox species through the polymer-modified colloidal film it is demonstrated that the polymer expands and contracts when the temperature was increased and decreased, respectively. We also observed an expansion and contraction as the pH was increased and decreased, respectively. Transport of a neutral dye molecule through free-standing silica colloidal films modified with poly(L-alanine) was also studied. As noted previously, the polymer expands and contracts as the pH is increased and decreased, respectively. Next, the transport was monitored through both silica colloidal film-modified Pt microelectrodes and Pt single nanopore electrodes as an oligonucleotide-based binder, or aptamer, was attached. The aptamer is responsive to a small molecule, cocaine where, in the absence of cocaine, only one "arm" of the aptamer is folded in on itself, leaving the rest of the chain partially unfolded, blocking the nanopores. However, when the cocaine molecule is introduced into solution, the aptamer folds completely in on itself, forming a three-armed structure with the small molecule encapsulated in the middle. This change in conformation is monitored by observing the change in transport of a redox species through the pores as cocaine is introduced into the system. We observed an increase rate of transport as the aptamer bound

  16. Elastic properties of protein functionalized nanoporous polymer films

    DOE PAGESBeta

    Charles T. Black; Wang, Haoyu; Akcora, Pinar

    2015-12-16

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that proteinmore » functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.« less

  17. Elastic Properties of Lysozyme Confined in Nanoporous Polymer Films

    NASA Astrophysics Data System (ADS)

    Wang, Haoyu; Akcora, Pinar

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. It is known that confined media provide a protective environment to the encapsulated proteins and prevent diffusion of the denaturant. In this study, different types of proteins (streptavidin, lysozyme and fibrinogen) were chemically attached into the nanopores of poly(methyl methacrylate) thin films. Heterogeneous flat surfaces with varying cylinder pore sizes (10-50 nm) were used to confine proteins of different sizes and shapes. Stiffness of protein functionalized nanopores was measured in nanoindentation experiments. Our results showed that streptavidin behaved more stiffly when pore dimension changed from micron to nanosize. Further, it was found that lysozyme confined within nanopores showed higher specific bioactivity than proteins on flat surfaces. These results on surface elasticity and protein activity may help in understanding protein interactions with surfaces of different topologies and chemistry.

  18. Detecting and identifying small molecules in a nanopore flux capacitor

    NASA Astrophysics Data System (ADS)

    Bearden, Samuel; McClure, Ethan; Zhang, Guigen

    2016-02-01

    A new method of molecular detection in a metallic-semiconductor nanopore was developed and evaluated with experimental and computational methods. Measurements were made of the charging potential of the electrical double layer (EDL) capacitance as charge-carrying small molecules translocated the nanopore. Signals in the charging potential were found to be correlated to the physical properties of analyte molecules. From the measured signals, we were able to distinguish molecules with different valence charge or similar valence charge but different size. The relative magnitude of the signals from different analytes was consistent over a wide range of experimental conditions, suggesting that the detected signals are likely due to single molecules. Computational modeling of the nanopore system indicated that the double layer potential signal may be described in terms of disruption of the EDL structure due to the size and charge of the analyte molecule, in agreement with Huckel and Debye’s analysis of the electrical atmosphere of electrolyte solutions.

  19. Elastic Properties of Protein Functionalized Nanoporous Polymer Films.

    PubMed

    Wang, Haoyu; Black, Charles T; Akcora, Pinar

    2016-01-12

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Our results show that protein functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces. PMID:26672623

  20. Elastic properties of protein functionalized nanoporous polymer films

    SciTech Connect

    Charles T. Black; Wang, Haoyu; Akcora, Pinar

    2015-12-16

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that protein functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.

  1. Transport behavior of water molecules through two-dimensional nanopores

    SciTech Connect

    Zhu, Chongqin; Li, Hui; Meng, Sheng

    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.

  2. Characterization of electroosmotic flow through nanoporous self-assembled arrays.

    PubMed

    Bell, Kevan; Gomes, Mikel; Nazemifard, Neda

    2015-08-01

    Characterization of EOF mobility for Tris and TBE buffer solutions is performed in nanoporous arrays using the fluorescent marker method to examine the magnitude of EOFs through nanopores with mean diameters close to electric double layer thickness (Debye length). Structures made from solid silica nanospheres with effective pore sizes from 104 nm down to 8 nm are produced within the microchannel using an evaporation self-assembly method. EOF results in nanoporous matrices show higher EOF mobilities for stronger electrolyte solutions, which are drastically different compared to microchannel EOF. The effects of scaling are also examined by comparing the EOF mobility for varying ratios of pore diameters to the Debye length, which shows a surprising consistency across all particle sizes examined. This work demonstrates various factors which must be considered when designing nanofluidic devices, and discusses the causes of these small scale effects. PMID:25964193

  3. [FTIR analysis of oil shales from Huadian Jilin and their pyrolysates].

    PubMed

    Xie, Fang-Fang; Wang, Ze; Song, Wen-Li; Lin, Wei-Gang

    2011-01-01

    Thermochemical conversion is the key technology for the comprehensive utilization of Chinese oil shale resources. Oil shales from three mining areas of Huadian Jilin were pyrolyzed at 500 degrees C in a quartz tube reactor and their pyrolyzed cokes and shale oil were derived. One oil shale was also pyrolyzed at 600 degrees C and 700 degrees C to assess the influence of temperature on pyrolysates. FTIR analysis was carried out to study the raw shales and their products. The results showed that shale oil had similar functional groups as the organic matter of oil shale, mainly aliphatic hydrocarbon, and the shale oil contained more of it than the raw material. The shale with more aliphatic oil yielded more oil. That with less aliphatic and more aromatic one yields less oil, and its coke is rich in condensed aromatics. Pyrolysis was almost completed at 500 degrees C. Oil yield did not increase further with temperature, but secondary pyrolysis strengthened. At 700 degrees C carbonates began to decompose. PMID:21428064

  4. Activated carbon from pyrolysed sugarcane bagasse: Silver nanoparticle modification and ecotoxicity assessment.

    PubMed

    Gonçalves, Suely Patrícia C; Strauss, Mathias; Delite, Fabrício S; Clemente, Zaira; Castro, Vera L; Martinez, Diego Stéfani T

    2016-09-15

    Activated carbon from pyrolysed sugarcane bagasse (ACPB) presented pore size ranges from 1.0 to 3.5nm, and surface area between 1200 and 1400m(2)g(-1) that is higher than commonly observed to commercial activated carbon. The ACPB material was successfully loaded with of silver nanoparticles with diameter around 35nm (0.81wt.%). X-ray photoelectron spectroscopy (XPS) analyses showed that the material surface contains metallic/Ag(0) (93.60wt.%) and ionic/Ag(+) states (6.40wt.%). The adsorption capacity of organic model molecules (i.e. methylene blue and phenol) was very efficient to ACPB and ACPB loaded with silver nanoparticles (ACPB-AgNP), indicating that the material modification with silver nanoparticles has not altered its adsorption capacity. ACPB-AgNP inhibited bacteria growth (Escherichia coli), it is a promising advantage for the use of these materials in wastewater treatment and water purification processes. However, ACPB-AgNP showed environmental risks, with toxic effect to the aquatic organism Hydra attenuata (i.e. LC50 value of 1.94mgL(-1)), and it suppressed root development of Lycopersicum esculentum plant (tomato). Finally, this work draw attention for the environmental implications of activated carbon materials modified with silver nanoparticles. PMID:27039274

  5. Long-chain carboxylic acids in pyrolysates of Green River kerogen

    NASA Technical Reports Server (NTRS)

    Kawamura, K.; Tannenbaum, E.; Huizinga, B. J.; Kaplan, I. R.

    1986-01-01

    Long-chain fatty acids (C10-C32), as well as C14-C21 isoprenoid acids (except for C18), have been identified in anhydrous and hydrous pyrolyses products of Green River kerogen (200-400 degrees C, 2-1000 hr). These kerogen-released fatty acids are characterized by a strong even/odd predominance (CPI: 4.8-10.2) with a maximum at C16 followed by lesser amounts of C18 and C22 acids. This distribution is different from that of unbound and bound geolipids extracted from Green River shale. The unbound fatty acids show a weak even/odd predominance (CPI: 1.64) with a maximum at C14, and bound fatty acids display an even/odd predominance (CPI: 2.8) with maxima at C18 and C30. These results suggest that fatty acids were incorporated into kerogen during sedimentation and early diagenesis and were protected from microbial and chemical changes over geological periods of time. Total quantities of fatty acids produced during heating of the kerogen ranged from 0.71 to 3.2 mg/g kerogen. Highest concentrations were obtained when kerogen was heated with water for 100 hr at 300 degrees C. Generally, their amounts did not decrease under hydrous conditions with increase in temperature or heating time, suggesting that significant decarboxylation did not occur under the pyrolysis conditions used, although hydrocarbons were extensively generated.

  6. Elastic characterization of nanoporous gold foams using laser based ultrasonics.

    PubMed

    Ahn, Phillip; Balogun, Oluwaseyi

    2014-03-01

    A resonance based laser ultrasonics technique is explored for the characterization of low density nanoporous gold foams. Laser generated zero group velocity (ZGV) lamb waves are measured in the foams using a Michelson interferometer. The amplitude spectra obtained from the processed time-domain data are analyzed using a theoretical model from which the foam Young's modulus and Poisson's ratio are obtained. The technique is non-contact and nondestructive, and the ZGV resonance modes are spatially localized, allowing for spatial mapping of the bulk sample properties. The technique may be suitable for process control monitoring and mechanical characterization of low density nanoporous structures. PMID:24524154

  7. Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support

    NASA Astrophysics Data System (ADS)

    Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

    2013-06-01

    Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

  8. Photo-response of a nanopore device with a single embedded ZnO nanoparticle

    NASA Astrophysics Data System (ADS)

    Nguyen, Linh-Nam; Lin, Ming-Chou; Chen, Horng-Shyang; Lan, Yann-Wen; Wu, Cen-Shawn; Chang-Liao, Kuei-Shu; Chen, Chii-Dong

    2012-04-01

    The photo-response of a ZnO nanoparticle embedded in a nanopore made on a silicon nitride membrane is investigated. The ZnO nanoparticle is manipulated onto the nanopore and sandwiched between aluminum contact electrodes from both the top and bottom. The asymmetric device structure facilitates current-voltage rectification that enables photovoltaic capacity. Under illumination, the device shows open-circuit voltage as well as short-circuit current. The fill factor is found to increase at low temperatures and reaches 48.6% at 100 K. The nanopore structure and the manipulation technique provide a solid platform for exploring the electrical properties of single nanoparticles.

  9. Applications of Nanoporous Materials in Agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nanoporous materials possess organized pore distributions and increased surface areas. Advances in the systematic design of nanoporous materials enable incorporation of functionality for better sensitivity in detection methods, increased capacity of sorbents, and improved selectivity and yield in ca...

  10. An all-in-one nanopore battery array.

    PubMed

    Liu, Chanyuan; Gillette, Eleanor I; Chen, Xinyi; Pearse, Alexander J; Kozen, Alexander C; Schroeder, Marshall A; Gregorczyk, Keith E; Lee, Sang Bok; Rubloff, Gary W

    2014-12-01

    A single nanopore structure that embeds all components of an electrochemical storage device could bring about the ultimate miniaturization in energy storage. Self-alignment of electrodes within each nanopore may enable closer and more controlled spacing between electrodes than in state-of-art batteries. Such an 'all-in-one' nanopore battery array would also present an alternative to interdigitated electrode structures that employ complex three-dimensional geometries with greater spatial heterogeneity. Here, we report a battery composed of an array of nanobatteries connected in parallel, each composed of an anode, a cathode and a liquid electrolyte confined within the nanopores of anodic aluminium oxide, as an all-in-one nanosize device. Each nanoelectrode includes an outer Ru nanotube current collector and an inner nanotube of V₂O₅ storage material, forming a symmetric full nanopore storage cell with anode and cathode separated by an electrolyte region. The V₂O₅ is prelithiated at one end to serve as the anode, with pristine V₂O₅ at the other end serving as the cathode, forming a battery that is asymmetrically cycled between 0.2 V and 1.8 V. The capacity retention of this full cell (relative to 1 C values) is 95% at 5 C and 46% at 150 C, with a 1,000-cycle life. From a fundamental point of view, our all-in-one nanopore battery array unveils an electrochemical regime in which ion insertion and surface charge mechanisms for energy storage become indistinguishable, and offers a testbed for studying ion transport limits in dense nanostructured electrode arrays. PMID:25383515

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

    SciTech Connect

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

    2007-09-28

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

  12. Plasmonic nanopore-based platforms for single-molecule Raman scattering

    NASA Astrophysics Data System (ADS)

    Deng, Liang; Wang, Yixin; Liu, Chen; Hu, Dora Juan Juan; Shum, Perry Ping; Su, Lei

    2016-08-01

    We propose and demonstrate a novel plasmonic nanopore platform based on a bowtie-nanopore structure, for single-molecule sensing. In this nano-structure, nano-bowties are integrated with solid-state nanopores to provide localized surface plasmon resonances for signal enhancement. We design and optimize the nano-structure by tuning both the bowtie gap and the bowtie angle, and investigate their influences on field enhancement, thereby achieving single-molecule sensitivity. In addition, we study the field enhancement by introducing an engineered photonic nano-cavity. This further strengthens the electric enhancement. An overall Raman enhancement factor of 2×108 is achieved in our simulation. This is believed to be sufficient for single-molecule sensing. The proposed bowtie-nanopore structure can be multiplexed on a single substrate for simultaneous multi-channel detection, paving the way for demanding applications such as DNA sequencing.

  13. Effect of Graphene with Nanopores on Metal Clusters

    SciTech Connect

    Zhou, Hu; Chen, Xianlang; Wang, Lei; Zhong, Xing; Zhuang, Guilin; Li, Xiaonian; Mei, Donghai; Wang, Jianguo

    2015-10-07

    Porous graphene, which is a novel type of defective graphene, shows excellent potential as a support material for metal clusters. In this work, the stability and electronic structures of metal clusters (Pd, Ir, Rh) supported on pristine graphene and graphene with different sizes of nanopore were investigated by first-principle density functional theory (DFT) calculations. Thereafter, CO adsorption and oxidation reaction on the Pd-graphene system were chosen to evaluate its catalytic performance. Graphene with nanopore can strongly stabilize the metal clusters and cause a substantial downshift of the d-band center of the metal clusters, thus decreasing CO adsorption. All binding energies, d-band centers, and adsorption energies show a linear change with the size of the nanopore: a bigger size of nanopore corresponds to a stronger metal clusters bond to the graphene, lower downshift of the d-band center, and weaker CO adsorption. By using a suitable size nanopore, supported Pd clusters on the graphene will have similar CO and O2 adsorption ability, thus leading to superior CO tolerance. The DFT calculated reaction energy barriers show that graphene with nanopore is a superior catalyst for CO oxidation reaction. These properties can play an important role in instructing graphene-supported metal catalyst preparation to prevent the diffusion or agglomeration of metal clusters and enhance catalytic performance. This work was supported by National Basic Research Program of China (973Program) (2013CB733501), the National Natural Science Foundation of China (NSFC-21176221, 21136001, 21101137, 21306169, and 91334013). D. Mei acknowledges the support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational

  14. Graphene nanopores as negative differential resistance devices

    SciTech Connect

    Qiu, Wanzhi; Nguyen, Phuong Duc; Skafidas, Efstratios

    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.

  15. Biosensing with integrated CMOS nanopores

    NASA Astrophysics Data System (ADS)

    Uddin, Ashfaque; Yemenicioglu, Sukru; Chen, Chin-Hsuan; Corgliano, Ellie; Milaninia, Kaveh; Xia, Fan; Plaxco, Kevin; Theogarajan, Luke

    2012-10-01

    This paper outlines our recent efforts in using solid-state nanopores as a biosensing platform. Traditionally biosensors concentrate mainly on the detection platform and not on signal processing. This decoupling can lead to inferior sensors and is exacerbated in nanoscale devices, where device noise is large and large dynamic range is required. This paper outlines a novel platform that integrates the nano, micro and macroscales in a closely coupled manner that mitigates many of these problems. We discuss our initial results of DNA translocation through the nanopore. We also briefly discuss the use of molecular recognition properties of aptamers with the versatility of the nanopore detector to design a new class of biosensors in a CMOS compatible platform.

  16. Nanopore Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bush, Joseph; Mihovilovic, Mirna; Maulbetsch, William; Frenchette, Layne; Moon, Wooyoung; Pruitt, Cole; Bazemore-Walker, Carthene; Weber, Peter; Stein, Derek

    2013-03-01

    We report on the design, construction, and characterization of a nanopore-based ion source for mass spectrometry. Our goal is to field-extract ions directly from solution into the high vacuum to enable unit collection efficiency and temporal resolution of sequential ion emissions for DNA sequencing. The ion source features a capillary whose tip, measuring tens to hundreds of nanometers in inner diameter, is situated in the vacuum ~ 1.5 cm away from an extractor electrode. The capillary was filled with conductive solution and voltage-biased relative to the extractor. Applied voltages of hundreds of volts extracted tens to hundreds of nA of current from the tip. A mass analysis of the extracted ions showed primarily singly charged clusters comprising the cation or anion solvated by several solvent molecules. Our interpretation of these results, based on the works of Taylor and of de la Mora, is that the applied electric stresses distort the fluid meniscus into a Taylor cone, where electric fields reach ~ 1V/nm and induce significant ion evaporation. Accordingly, the abundances of extracted ionic clusters resemble a Boltzmann distribution. This work was supported by NIH grant NHGRI 1R21HG005100-01.

  17. Nanoporous microscale microbial incubators.

    PubMed

    Ge, Zhifei; Girguis, Peter R; Buie, Cullen R

    2016-02-01

    Reconstruction of phylogenetic trees based on 16S rRNA gene sequencing reveals abundant microbial diversity that has not been cultured in the laboratory. Many attribute this so-called 'great plate count anomaly' to traditional microbial cultivation techniques, which largely facilitate the growth of a single species. Yet, it is widely recognized that bacteria in nature exist in complex communities. One technique to increase the pool of cultivated bacterial species is to co-culture multiple species in a simulated natural environment. Here, we present nanoporous microscale microbial incubators (NMMI) that enable high-throughput screening and real-time observation of multi-species co-culture. The key innovation in NMMI is that they facilitate inter-species communication while maintaining physical isolation between species, which is ideal for genomic analysis. Co-culture of a quorum sensing pair demonstrates that the NMMI can be used to culture multiple species in chemical communication while monitoring the growth dynamics of individual species. PMID:26584739

  18. Ion Beam Nanosculpting and Materials Science with Single Nanopores

    SciTech Connect

    Golovchenko, J A; Branton, D

    2009-10-03

    Work is reported in these areas: Nanopore studies; Ion sculpting of metals; High energy ion sculpting; Metrology of nanopores with single wall carbon nanotube probes; Capturing molecules in a nanopore; Strand separation in a nanopore; and DNA molecules and configurations in solid-state nanopores.

  19. Investigation of glass transition and dielectric behavior of nanoporous PEI (polyetherimide)

    NASA Astrophysics Data System (ADS)

    Liu, Tong

    Nanoporous polymers are of great interest for their potential applications as low dielectric constant materials in the microelectronics industry. In general, nanoporous polymers can be viewed as nanocomposite materials, which consist of three parts: polymer matrix, nanopores and the interface region surrounding the nanopores. Evidence has been shown that the interface region has unique properties different from the polymer matrix, which would cause property changes in the polymer nanocomposites. However, the understanding of the interface region and its influence on properties are still limited. Therefore, the main objectives of this work were to create a controlled nanoporous polymer structure and to investigate the interface effects on glass transition temperature and dielectric constant in the nanoporous polymer system. Nanoporous polyetherimide (PEI) was developed based on a blend of PEI and polycaprolactone-diol (PCLD). Because PEI and PCLD are immiscible, dispersed PCLD phase domains were formed in the PEI matrix. Nanoporous PEI was created by immersing the phase-separated samples in acetone, which dissolved the PCLD phase only. The pore size in spin-coated samples was found to be in the nanometer scale due to the fast phase separation process. In this case, the phase separation was far from thermal equilibrium, and kinetic factors played an important role in the process. The pore structure was characterized by microscopy methods. The pore size was found to depend on the processing time and the initial PCLD phase content (PCLD is the minor phase) due to the kinetics of phase coarsening. The glass transition temperature and dielectric constant of the nanoporous PEI system were investigated with various means. The relationship between the properties and the pore structure was studied by controlling the pore volume fraction through varying the initial minor phase content in the blend. It was found that the glass transition temperature of nanoporous PEI would

  20. Intermolecular Hybridization Creating Nanopore Orbital in a Supramolecular Hydrocarbon Sheet.

    PubMed

    Zhang, Yi-Qi; Björk, Jonas; Barth, Johannes V; Klappenberger, Florian

    2016-07-13

    Molecular orbital engineering is a key ingredient for the design of organic devices. Intermolecular hybridization promises efficient charge carrier transport but usually requires dense packing for significant wave function overlap. Here we use scanning tunneling spectroscopy to spatially resolve the electronic structure of a surface-confined nanoporous supramolecular sheet of a prototypical hydrocarbon compound featuring terminal alkyne (-CCH) groups. Surprisingly, localized nanopore orbitals are observed, with their electron density centered in the cavities surrounded by the functional moieties. Density functional theory calculations reveal that these new electronic states originate from the intermolecular hybridization of six in-plane π-orbitals of the carbon-carbon triple bonds, exhibiting significant electronic splitting and an energy downshift of approximately 1 eV. Importantly, these nanopore states are distinct from previously reported interfacial states. We unravel the underlying connection between the formation of nanopore orbital and geometric arrangements of functional groups, thus demonstrating the generality of applying related orbital engineering concepts in various types of porous organic structures. PMID:27253516

  1. [Preparation and infrared spectral analysis of nanoporous silica thin film].

    PubMed

    Wang, Juan; Zhang, Chang-rui; Feng, Jian; Yang, Da-xiang

    2005-07-01

    Crack-free homogeneous nanoporous silica films on silicon wafer have been synthesized via supercritical drying of wet gel films obtained by spin-coating the polymeric silica sol, which was prepared using sol-gel method with tetraethoxysilane (TEOS) as precursor. The film is amorphous and nanoporous, and three-dimensional network, cross-linked by the primary particles whose sizes distribute between 10-20 nm showed respectively by XRD and SEM micrograph. The structure of the nanoporous SiO2 thin film was studied by FTIR spectra. The SiO2 thin film was composed of Si-O-Si and Si-OR, and was hydrophobic. The film contained Si-OH and became hydrophilic after being heat-treated at 250 degrees C or above in air. The heat-treated SiO2 thin film becomes hydrophobic by reacting with trimethylchlorosilane(TMCS). The TMCS-modified SiO2 thin film remains hydrophobic and can keep its nanoporous structure at a temperature lower than 450 degrees C in nitrogen. PMID:16241051

  2. Structuring and electric conductivity of polymer composites pyrolysed at high temperatures

    NASA Astrophysics Data System (ADS)

    Aneli, J. N.; Natriashvili, T. M.; Zaikov, G. E.

    2014-05-01

    On the basis of mixes of phenolformaldehide and epoxy resins at presence of some silicon organic compounds and fiber glasses annealed in vacuum and hydrogen media the new conductive monolithic materials have been created. There were investigated the conductive, magnetic and some other properties of these materials. It is established experimentally that the obtained products are characterized by semiconducting properties, the level of conductivity of which are regulated by selection of technological conditions. The density and mobility of charge carriers increase at increasing of annealing temperature up to definite levels. The temperature dependence of the electrical conductivity and charge mobility describe by Mott formulas. It is established that at annealing free radicals and other paramagnetic centers are formed. Iit is proposed that charge transport between conducting clusters provides by mechanism of charge jumping with alternative longevity of the jump.

  3. Irradiation response and stability of nanoporous materials

    SciTech Connect

    Fu, Engang; Wang, Yongqiang; Serrano De Caro, Magdalena; Caro, Jose A.; Zepeda-Ruiz, L; Bringa, E.; Nastasi, Mike; Baldwin, Jon K.

    2012-08-28

    Nanoporous materials consist of a regular organic or inorganic framework supporting a regular, porous structure. Pores are by definition roughly in the nanometre range, that is between 0.2 nm and 100 nm. Nanoporous materials can be subdivided into 3 categories (IUPAC): (1) Microporous materials - 0.2-2 nm; (2) Mesoporous materials - 2-50 nm; and (3) Macroporous materials - 50-1000 nm. np-Au foams were successfully synthesized by de-alloying process. np-Au foams remain porous structure after Ne ion irradiation to 1 dpa. Stacking Fault Tetrahedra (SFTs) were observed in RT irradiated np-Au foams under the highest and intermediate fluxes, but not under the lowest flux. SFTs were not observed in LNT irradiated np-Au foams under all fluxes. The vacancy diffusivity in Au at RT is high enough so that the vacancies have enough time to agglomerate and then collapse to form SFTs. The high ion flux creates more damage per unit time; vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed at high ion fluxes.

  4. Water confinement in nanoporous silica materials

    SciTech Connect

    Renou, Richard; Szymczyk, Anthony; Ghoufi, Aziz

    2014-01-28

    The influence of the surface polarity of cylindrical silica nanopores and the presence of Na{sup +} ions as compensating charges on the structure and dynamics of confined water has been investigated by molecular dynamics simulations. A comparison between three different matrixes has been included: a protonated nanopore (PP, with SiOH groups), a deprotonated material (DP, with negatively charged surface groups), and a compensated-charge framework (CC, with sodium cations compensating the negative surface charge). The structure of water inside the different pores shows significant differences in terms of layer organization and hydrogen bonding network. Inside the CC pore the innermost layer is lost to be replaced by a quasi bulk phase. The electrostatic field generated by the DP pore is felt from the surface to the centre of pore leading to a strong orientation of water molecules even in the central part of the pore. Water dynamics inside both the PP and DP pores shows significant differences with respect to the CC pore in which the sub-diffusive regime of water is lost for a superdiffusive regime.

  5. Noncovalent functionalization of solid-state nanopores via self-assembly of amphipols

    NASA Astrophysics Data System (ADS)

    Pérez-Mitta, Gonzalo; Burr, Loïc; Tuninetti, Jimena S.; Trautmann, Christina; Toimil-Molares, María Eugenia; Azzaroni, Omar

    2016-01-01

    In recent years there has been increasing interest in the development of new methods for conferring functional features to nanopore-based fluidic devices. In this work, we describe for the first time the noncovalent integration of amphoteric-amphipathic polymers, also known as ``amphipols'', into single conical nanopores in order to obtain signal-responsive chemical nanodevices. Highly-tapered conical nanopores were fabricated by single-sided chemical etching of polycarbonate foils. After etching, the surface of the conical nanopores was chemically modified, by first metallizing the surface via gold sputtering and then by amphiphilic self-assembly of the amphipol. The net charge of adsorbed amphipols was regulated via pH changes under the environmental conditions. The pH-dependent chemical equilibrium of the weak acidic and basic monomers facilitates the regulation of the ionic transport through the nanopore by adjusting the pH of the electrolyte solution. Our results demonstrate that functional amphipathic polymers are powerful building blocks for the surface modification of nanopores and might ultimately pave the way to a new means of integrating functional and/or responsive units within nanofluidic structures.In recent years there has been increasing interest in the development of new methods for conferring functional features to nanopore-based fluidic devices. In this work, we describe for the first time the noncovalent integration of amphoteric-amphipathic polymers, also known as ``amphipols'', into single conical nanopores in order to obtain signal-responsive chemical nanodevices. Highly-tapered conical nanopores were fabricated by single-sided chemical etching of polycarbonate foils. After etching, the surface of the conical nanopores was chemically modified, by first metallizing the surface via gold sputtering and then by amphiphilic self-assembly of the amphipol. The net charge of adsorbed amphipols was regulated via pH changes under the environmental

  6. A Mask-Free Passivation Process for Low Noise Nanopore Devices.

    PubMed

    Lim, Min-Cheol; Lee, Min-Hyun; Kim, Ki-Bum; Jeon, Tae-Joon; Kim, Young-Rok

    2015-08-01

    Solid-state nanopores have been studied widely for the label-free analysis of single biomolecules. The translocation of charged biomolecules through a solid-state nanopore is driven by the applied voltage across a thin membrane. The ionic current changes in response to the translocation of DNA through the nanopore. Solid-state nanopores have many advantages over biological nanopores, such as α-hemolysin and MspA, but the high DNA translocation velocity and the inherent noise in solid-state nanopores have hindered its applications to more precise measurements, such as DNA sequencing. This paper reports a simple and reproducible way of passivating the surface of a nanopore device using an insulating layer, photodefinable PDMS (P-PDMS), to reduce noise and enhance the accuracy of the electrical measurements. This new approach does not require a separate photo-mask or sophisticated micro-alignment equipment to pattern the insulating layer. The pit structure on the back side of the support chip serves as a mask, enabling mask-free photolithography, and the insulating layer only on top of the free-standing silicon nitride membrane can be irradiated selectively by UV and removed by subsequent development in toluene. The resulting nanopore device with a small free standing silicon nitride membrane surrounded by a thick insulating layer showed improved noise characteristics. The root-mean-square noise of the ionic current was reduced to 3.8 pA from 90.8 pA by the formation of a micron-thick insulating layer. The overall performance of the nanopores with an insulating layer was improved significantly when tested with the double-stranded DNA (λ-DNA). PMID:26369183

  7. Multilevel description of the DNA molecule translocation in solid-state synthetic nanopores

    NASA Astrophysics Data System (ADS)

    Nosik, V. L.; Rudakova, E. B.

    2016-07-01

    Interest of researchers in micro- and nanofluidics of polymer solutions and, in particular, DNA ionic solutions is constantly increasing. The use of DNA translocation with a controlled velocity through solid-state nanopores and pulsed X-ray beams in new sequencing schemes opens up new possibilities for studying the structure of DNA and other biopolymers. The problems related to the description of DNA molecular motion in a limited volume of nanopore are considered.

  8. Ion transport in sub-5-nm graphene nanopores

    NASA Astrophysics Data System (ADS)

    Suk, Myung E.; Aluru, N. R.

    2014-02-01

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

  9. Ultrasmall Silver Nanopores Fabricated by Femtosecond Laser Pulses

    NASA Astrophysics Data System (ADS)

    Zhao, Jimin; Bian, F.; Tian, Y. C.; Wang, R.; Yang, H. X.; Xu, Hongxing; Meng, Sheng

    2012-02-01

    Ultrasmall nanopores in silver thin films with a diameter of about 2 nm have been fabricated using femtosecond laser ablation in liquid [1]. Ultrafast laser pulse ablation generates highly nonequilibrium excitated states, from which silver thin films emerge and progressively grow with the assistance of capping agent molecules. During this growth process, capping agent molecules are enclaves within the film, leaving individual ultrasmall pores in the thin film. Our first-principles calculations show that the pore size is critically determined by the dimension of the confined molecules. Furthermore, by using smaller capping agent molecules, we were able to fabricate smaller nanopores with 1.6nm diameter. Our approach advances the capability of optical methods in making nanoscale structures with potential applications in areas such as near-field aperture probes, imaging masks, magnetic plasmonic resonances, and biosensing with individual nanopores. [4pt] [1] F. Bian, Y. C. Tian, R. Wang, H. X. Yang, H. X. Xu, Sheng Meng, and Jimin Zhao, Ultrasmall Silver Nanopores Fabricated by Femtosecond Laser Pulses, Nano Lett. 11, 3251--3257 (2011).

  10. Probe DNA-Cisplatin Interaction with Solid-State Nanopores

    NASA Astrophysics Data System (ADS)

    Zhou, Zhi; Hu, Ying; Li, Wei; Xu, Zhi; Wang, Pengye; Bai, Xuedong; Shan, Xinyan; Lu, Xinghua; Nanopore Collaboration

    2014-03-01

    Understanding the mechanism of DNA-cisplatin interaction is essential for clinical application and novel drug design. As an emerging single-molecule technology, solid-state nanopore has been employed in biomolecule detection and probing DNA-molecule interactions. Herein, we reported a real-time monitoring of DNA-cisplatin interaction by employing solid-state SiN nanopores. The DNA-cisplatin interacting process is clearly classified into three stages by measuring the capture rate of DNA-cisplatin adducts. In the first stage, the negative charged DNA molecules were partially discharged due to the bonding of positive charged cisplatin and forming of mono-adducts. In the second stage, forming of DNA-cisplatin di-adducts with the adjacent bases results in DNA bending and softening. The capture rate increases since the softened bi-adducts experience a lower barrier to thread into the nanopores. In the third stage, complex structures, such as micro-loop, are formed and the DNA-cisplatin adducts are aggregated. The capture rate decreases to zero as the aggregated adduct grows to the size of the pore. The characteristic time of this stage was found to be linear with the diameter of the nanopore and this dynamic process can be described with a second-order reaction model. We are grateful to Laboratory of Microfabrication, Dr. Y. Yao, and Prof. R.C. Yu (Institute of Physics, Chinese Academy of Sciences) for technical assistance.

  11. Ion transport in sub-5-nm graphene nanopores

    SciTech Connect

    Suk, Myung E.; Aluru, N. R.

    2014-02-28

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

  12. Restricted dynamics of molecular hydrogen confined in activated carbon nanopores

    SciTech Connect

    Contescu, Cristian I; Saha, Dipendu; Gallego, Nidia C; Mamontov, Eugene; Kolesnikov, Alexander I; Bhat, Vinay V

    2012-01-01

    Quasi-elastic neutron scattering was used for characterization of dynamics of molecular hydrogen confined in narrow nanopores of two activated carbon materials: PFAC (derived from polyfurfuryl alcohol) and UMC (ultramicroporous carbon). Fast, but incomplete ortho-para conversion was observed at 10 K, suggesting that scattering originates from the fraction of unconverted ortho isomer which is rotation-hindered because of confinement in nanopores. Hydrogen molecules entrapped in narrow nanopores (<7 ) were immobile below 22-25 K. Mobility increased rapidly with temperature above this threshold, which is 8 K higher than the melting point of bulk hydrogen. Diffusion obeyed fixed-jump length mechanism, indistinguishable between 2D and 3D processes. Thermal activation of diffusion was characterized between ~22 and 37 K, and structure-dependent differences were found between the two carbons. Activation energy of diffusion was higher than that of bulk solid hydrogen. Classical notions of liquid and solid do not longer apply for H2 confined in narrow nanopores.

  13. Design of nanoporous materials with optimal sorption capacity

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Urita, Koki; Moriguchi, Isamu; Tartakovsky, Daniel M.

    2015-06-01

    Modern technological advances have enabled one to manufacture nanoporous materials with a prescribed pore structure. This raises a possibility of using controllable pore-scale parameters (e.g., pore size and connectivity) to design materials with desired macroscopic properties (e.g., diffusion coefficient and adsorption capacity). By relating these two scales, the homogenization theory (or other upscaling techniques) provides a means of guiding the experimental design. To demonstrate this approach, we consider a class of nanoporous materials whose pore space consists of nanotunnels interconnected by nanotube bridges. Such hierarchical nanoporous carbons with mesopores and micropores have shown high specific electric double layer capacitances and high rate capability in an organic electrolyte. We express the anisotropic diffusion coefficient and adsorption coefficient of such materials in terms of the tunnels' properties (pore radius and inter-pore throat width) and their connectivity (spacing between the adjacent tunnels and nanotube-bridge density). Our analysis is applicable for solutes that undergo a non-equilibrium Langmuir adsorption reaction on the surfaces of fluid-filled pores, but other homogeneous and heterogeneous reactions can be handled in a similar fashion. The presented results can be used to guide the design of nanoporous materials with optimal permeability and sorption capacity.

  14. Ion Beam Energy Dependant Study of Nanopore Sculpting

    NASA Astrophysics Data System (ADS)

    Ledden, Brad

    2005-03-01

    Experiments show that ion beams of various energies (1keV, 3keV, and 5keV) can be used to controllably ``sculpt'' nanoscale features in silicon nitride films using a feedback controlled ion beam sculpting apparatus. We report on nanopore ion beam sculpting effects that depend on inert gas ion beam energy. We show that: (1) all ion beam energies enable single nanometer control of structural dimensions in nanopores; (2) the ion beam energies above show similar ion beam flux dependence of nanopore formation; (3) the thickness of nanopores differs depending on ion beam energy. Computer simulations (with SRIM and TRIM) and an ``adatom'' surface diffusion model are employed to explain the dynamics of nanoscale dimension change by competing sputtering and surface mass transport processes induced by different ion beam irradiation. These experiments and theoretical work reveal the surface atomic transport phenomena in a quantitative way that allows the extraction of parameters such as the adatom surface diffusion coefficients and average travel distances.

  15. Nanopore Sculpting with Low Energy Ion Beam of Noble Gases

    NASA Astrophysics Data System (ADS)

    Cai, Qun; Ledden, Brad; Krueger, Eric; Golovchenko, Jene; Li, Jiali

    2005-03-01

    Experiments show that 3keV Helium, Neon, Argon, Krypton, and Xenon ion beams can be used to controllably ``sculpt'' nanoscale features in silicon nitride films using a feedback controlled ion beam sculpting apparatus. Here we report nanopore ion beam sculpting effects that depend on the inert gas ion species. We demonstrate that: (1) all the noble gas ion beams enable single nanometer control of structural dimensions in nanopores; (2) every ion species above shows similar ion beam flux dependence of nanopore formation, (3) the thickness of nanopores sculpted with different inert gas ion beam is deferent. Computer simulations (with SRIM and TRIM) and an ``adatom'' surface diffusion model are employed to explain the dynamics of nanoscale dimension change by competing sputtering and surface mass transport processes induced by different ion beam irradiation. These experiments and theoretical work reveal the surface atomic transport phenomena in a quantitative way that allows the extraction of parameters such as the adatom surface diffusion coefficients and average travel distances.

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

    SciTech Connect

    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. Production and characterization of polypropylene composites filled with glass fibre recycled from pyrolysed waste printed circuit boards.

    PubMed

    Li, Shenyong; Sun, Shuiyu; Liang, Haifeng; Zhong, Sheng; Yang, Fan

    2014-01-01

    Waste printed circuit boards (WPCBs) are composed of nearly 70% non-metals, which are generally recycled as low-value filling materials or even directly dumped in landfills. In this study, polypropylene (PP) composites reinforced by recycled pure glass fibres (RGF) from pyrolysed WPCBs were successfully produced. The manufacturing process, mechanical properties and thermal behaviour of the composites were investigated. The results showed that the appropriate addition of RGF in the composites can significantly improve the mechanical properties and thermal behaviour. When the added content of RGF was 30%, the maximum increment of tensile strength, impact strength, flexural strength and flexural modulus of the glass fibre (GF)/PP composites are 25.93%, 41.38%, 31.16% and 68.42%, respectively, and the vicat softening temperature could rise by 4.6°C. Furthermore, leaching of the GF/PP composites was also investigated. The GF/PP composites exhibited high performance and non-toxicity, offering a promising method to recycle RGF from pyrolysed WPCBs with high-value applications. PMID:25176309

  18. Preparation and characterization of bio-oils from internally circulating fluidized-bed pyrolyses of municipal, livestock, and wood waste.

    PubMed

    Cao, Jing-Pei; Xiao, Xian-Bin; Zhang, Shou-Yu; Zhao, Xiao-Yan; Sato, Kazuyoshi; Ogawa, Yukiko; Wei, Xian-Yong; Takarada, Takayuki

    2011-01-01

    Fast pyrolyses of sewage sludge (SS), pig compost (PC), and wood chip (WC) were investigated in an internally circulating fluidized-bed to evaluate bio-oil production. The pyrolyses were performed at 500 °C and the bio-oil yields from SS, PC, and WC were 45.2%, 44.4%, and 39.7% (dried and ash-free basis), respectively. The bio-oils were analyzed with an elemental analyzer, Karl-Fischer moisture titrator, bomb calorimeter, Fourier transformation infrared spectrometer, gel permeation chromatograph, and gas chromatography/mass spectrometry. The results show that the bio-oil from SS is rich in aliphatic and organonitrogen species, while the bio-oil from PC exhibits higher caloric value due to its higher carbon content and lower oxygen content in comparison with that from SS. The bio-oils from SS and PC have similar chemical composition of organonitrogen species. Most of the compounds detected in the bio-oil from WC are organooxygen species. Because of its high oxygen content, low H/C ratio, and caloric value, the bio-oil from WC is unfeasible for use as fuel feedstock, but possible for use as chemical feedstock. PMID:20943376

  19. Hyper-dendritic nanoporous zinc foam anodes

    DOE PAGESBeta

    Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya; Davies, Daniel; Bhadra, Shoham; Van Tassell, Barry.; Erdonmez, Can; Steingart, Daniel A.

    2015-04-24

    The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrastmore » to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.« less

  20. Hyper-dendritic nanoporous zinc foam anodes

    SciTech Connect

    Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya; Davies, Daniel; Bhadra, Shoham; Van Tassell, Barry.; Erdonmez, Can; Steingart, Daniel A.

    2015-04-24

    The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrast to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.

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

    PubMed

    Zharov, Ilya; Khabibullin, Amir

    2014-02-18

    binding. When we modify the surface of the colloidal nanopores with ionizable moieties, they can generate an electric field inside the nanopores, which repels ions of the same charge and attracts ions of the opposite charge. This allows us to electrostatically gate the ionic flux through colloidal nanopores, controlled by pH and ionic strength of the solution when surface amines or sulfonic acids are present or by irradiation with light in the case of surface spiropyran moieties. When we modify the surface of the colloidal nanopores with chiral moieties capable of stereoselective binding of enantiomers, we generate colloidal films with chiral permselectivity. By filling the colloidal nanopores with polymer brushes attached to the pore surface, we can control the ionic flux through the corresponding films and membranes electrostatically using reversibly ionizable polymer brushes. By filling the colloidal nanopores with polymer brushes whose conformation reversibly changes in response to pH, ionic strength, temperature, or small molecule binding, we can control the molecular flux sterically. There are various potential applications for surface-modified silica colloidal films and membranes. Due to their ordered nanoporous structure and mechanical durability, they are beneficial in nanofluidics, nanofiltration, separations, and fuel cells and as catalyst supports. Reversible gating of flux by external stimuli may be useful in drug release, in size-, charge-, and structure-selective separations, and in microfluidic and sensing devices. PMID:24397245

  2. Propylene/propane permeation properties of ethyl cellulose (EC) mixed matrix membranes fabricated by incorporation of nanoporous graphene nanosheets

    PubMed Central

    Yuan, Bingbing; Sun, Haixiang; Wang, Tao; Xu, Yanyan; Li, Peng; Kong, Ying; Niu, Q. Jason

    2016-01-01

    Nanopore containing graphene nanosheets were synthesized by graphene oxide and a reducing agent using a facile hydrothermal treatment in sodium hydroxide media. The as-prepared nanoporous graphene was incorporated into ethyl cellulose (EC) to prepare the mixed matrix membranes (MMMs) for C3H6/C3H8 separation. Transmission electron microscopy (TEM) photograph and X-ray photoelectron spectroscopy (XPS) analysis of nanoporous graphene nanosheets indicated that the structure of nano-pore was irregular and the oxygen-containing groups in the surface were limited. More importantly, the as-prepared MMMs presented better separation performance than that of pristine EC membrane due to simultaneous enhancement of C3H6 permeability and ideal selectivity. The ideal selectivity of the MMMs with 1.125 wt‰ nanoporous graphene content for C3H6/C3H8 increased from 3.45 to 10.42 and the permeability of C3H6 increased from 57.9 Barrer to 89.95 Barrer as compared with the pristine membrane. The presumed facilitated mechanism was that the high specific surface area of nanoporous graphene in polymer matrix increased the length of the tortuous pathway formed by nanopores for the gas diffusion as compared with the pristine graphene nanosheets, and generated a rigidified interface between the EC chains and fillers, thus enhanced the diffusivity selectivity. Therefore, it is expected that nanoporous graphene would be effective material for the C3H6/C3H8 separation. PMID:27352851

  3. Propylene/propane permeation properties of ethyl cellulose (EC) mixed matrix membranes fabricated by incorporation of nanoporous graphene nanosheets.

    PubMed

    Yuan, Bingbing; Sun, Haixiang; Wang, Tao; Xu, Yanyan; Li, Peng; Kong, Ying; Niu, Q Jason

    2016-01-01

    Nanopore containing graphene nanosheets were synthesized by graphene oxide and a reducing agent using a facile hydrothermal treatment in sodium hydroxide media. The as-prepared nanoporous graphene was incorporated into ethyl cellulose (EC) to prepare the mixed matrix membranes (MMMs) for C3H6/C3H8 separation. Transmission electron microscopy (TEM) photograph and X-ray photoelectron spectroscopy (XPS) analysis of nanoporous graphene nanosheets indicated that the structure of nano-pore was irregular and the oxygen-containing groups in the surface were limited. More importantly, the as-prepared MMMs presented better separation performance than that of pristine EC membrane due to simultaneous enhancement of C3H6 permeability and ideal selectivity. The ideal selectivity of the MMMs with 1.125 wt‰ nanoporous graphene content for C3H6/C3H8 increased from 3.45 to 10.42 and the permeability of C3H6 increased from 57.9 Barrer to 89.95 Barrer as compared with the pristine membrane. The presumed facilitated mechanism was that the high specific surface area of nanoporous graphene in polymer matrix increased the length of the tortuous pathway formed by nanopores for the gas diffusion as compared with the pristine graphene nanosheets, and generated a rigidified interface between the EC chains and fillers, thus enhanced the diffusivity selectivity. Therefore, it is expected that nanoporous graphene would be effective material for the C3H6/C3H8 separation. PMID:27352851

  4. Propylene/propane permeation properties of ethyl cellulose (EC) mixed matrix membranes fabricated by incorporation of nanoporous graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Yuan, Bingbing; Sun, Haixiang; Wang, Tao; Xu, Yanyan; Li, Peng; Kong, Ying; Niu, Q. Jason

    2016-06-01

    Nanopore containing graphene nanosheets were synthesized by graphene oxide and a reducing agent using a facile hydrothermal treatment in sodium hydroxide media. The as-prepared nanoporous graphene was incorporated into ethyl cellulose (EC) to prepare the mixed matrix membranes (MMMs) for C3H6/C3H8 separation. Transmission electron microscopy (TEM) photograph and X-ray photoelectron spectroscopy (XPS) analysis of nanoporous graphene nanosheets indicated that the structure of nano-pore was irregular and the oxygen-containing groups in the surface were limited. More importantly, the as-prepared MMMs presented better separation performance than that of pristine EC membrane due to simultaneous enhancement of C3H6 permeability and ideal selectivity. The ideal selectivity of the MMMs with 1.125 wt‰ nanoporous graphene content for C3H6/C3H8 increased from 3.45 to 10.42 and the permeability of C3H6 increased from 57.9 Barrer to 89.95 Barrer as compared with the pristine membrane. The presumed facilitated mechanism was that the high specific surface area of nanoporous graphene in polymer matrix increased the length of the tortuous pathway formed by nanopores for the gas diffusion as compared with the pristine graphene nanosheets, and generated a rigidified interface between the EC chains and fillers, thus enhanced the diffusivity selectivity. Therefore, it is expected that nanoporous graphene would be effective material for the C3H6/C3H8 separation.

  5. Nanoporous materials as new engineered catalysts for the synthesis of green fuels.

    PubMed

    Fechete, Ioana; Vedrine, Jacques C

    2015-01-01

    This review summarizes the importance of nanoporous materials and their fascinating structural properties with respect to the catalytic and photocatalytic reduction of CO2 to methane, toward achieving a sustainable energy supply. The importance of catalysis as a bridge step for advanced energy systems and the associated environmental issues are stressed. A deep understanding of the fundamentals of these nanoporous solids is necessary to improve the design and efficiency of CO2 methanation. The role of the support dominates the design in terms of developing an efficient methanation catalyst, specifically with respect to ensuring enhanced metal dispersion and a long catalyst lifetime. Nanoporous materials provide the best supports for Ni, Ru, Rh, Co, Fe particles because they can prevent sintering and deactivation through coking, which otherwise blocks the metal surface as carbon accumulates. This review concludes with the major challenges facing the CO2 methanation by nanoporous materials for fuel applications. PMID:25838169

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

    SciTech Connect

    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.

  7. The Effects of Geometry and Stability of Solid-state Nanopores on Detecting Single DNA molecules

    PubMed Central

    Rollings, Ryan; Graef, Edward; Walsh, Nathan; Nandivada, Santoshi; Benamara, Mourad

    2014-01-01

    In this work we use a combination of 3D-TEM tomography, energy filtered TEM, single molecule DNA translocation experiments, and numerical modeling to show a more precise relationship between nanopore shape and ionic conductance and show that changes in geometry while in solution can account for most deviations between predicted and measured conductance. We compare the structural stability of Ion Beam Sculpted (IBS), IBS-annealed, and TEM drilled nanopores. We demonstrate that annealing can significantly improve the stability of IBS made pores. Furthermore, the methods developed in this work can be used to predict pore conductance and current drop amplitudes of DNA translocation events for a wide variety of pore geometries. We discuss that chemical dissolution is one mechanism of the geometry change for SiNx nanopores and show that small modification in fabrication procedure can significantly increase the stability of IBS nanopores. PMID:25556317

  8. A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass.

    PubMed

    Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

    2016-12-01

    So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors. PMID:27225424

  9. A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass

    NASA Astrophysics Data System (ADS)

    Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

    2016-05-01

    So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

  10. Pulsed laser deposition and characterization of ZnO nanopores

    NASA Astrophysics Data System (ADS)

    Ghosh, Poulami; Sharma, Ashwini K.

    2016-04-01

    We report on the deposition and characterization of ZnO nanopore structures by pulsed laser deposition technique at a fixed substrate temperature and at different deposition times on a silicon (100) substrate. X-ray diffraction shows that ZnO nanopore structures are highly oriented along c-axis. Morphological analysis of the nanostructures studied by FESEM and AFM confirms the pores nature of the structures. The morphological evolution of the nanostructures as a function of deposition time is discussed on the basis of Stranski-Krastanov growth model. Optical properties of the nanostructures studied by photoluminescence spectra indicate that the observed transitions are from near band edge as well as from defect-related states.

  11. Enzyme Reactions in Nanoporous, Picoliter Volume Containers

    SciTech Connect

    Siuti, Piro; Retterer, Scott T; Choi, Chang Kyoung; Doktycz, Mitchel John

    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.

  12. Nanopore Sequencing: Electrical Measurements of the Code of Life

    PubMed Central

    Timp, Winston; Mirsaidov, Utkur M.; Wang, Deqiang; Comer, Jeff; Aksimentiev, Aleksei; Timp, Gregory

    2011-01-01

    Sequencing a single molecule of deoxyribonucleic acid (DNA) using a nanopore is a revolutionary concept because it combines the potential for long read lengths (>5 kbp) with high speed (1 bp/10 ns), while obviating the need for costly amplification procedures due to the exquisite single molecule sensitivity. The prospects for implementing this concept seem bright. The cost savings from the removal of required reagents, coupled with the speed of nanopore sequencing places the $1000 genome within grasp. However, challenges remain: high fidelity reads demand stringent control over both the molecular configuration in the pore and the translocation kinetics. The molecular configuration determines how the ions passing through the pore come into contact with the nucleotides, while the translocation kinetics affect the time interval in which the same nucleotides are held in the constriction as the data is acquired. Proteins like α-hemolysin and its mutants offer exquisitely precise self-assembled nanopores and have demonstrated the facility for discriminating individual nucleotides, but it is currently difficult to design protein structure ab initio, which frustrates tailoring a pore for sequencing genomic DNA. Nanopores in solid-state membranes have been proposed as an alternative because of the flexibility in fabrication and ease of integration into a sequencing platform. Preliminary results have shown that with careful control of the dimensions of the pore and the shape of the electric field, control of DNA translocation through the pore is possible. Furthermore, discrimination between different base pairs of DNA may be feasible. Thus, a nanopore promises inexpensive, reliable, high-throughput sequencing, which could thrust genomic science into personal medicine. PMID:21572978

  13. Fabrication of nanoporous thin-film working electrodes and their biosensing applications.

    PubMed

    Li, Tingjie; Jia, Falong; Fan, Yaxi; Ding, Zhifeng; Yang, Jun

    2013-04-15

    Electrochemical detection for point-of-care diagnostics is of great interest due to its high sensitivity, fast analysis time and ability to operate on a small scale. Herein, we report the fabrication of a nanoporous thin-film electrode and its application in the configuration of a simple and robust enzymatic biosensor. The nanoporous thin-film was formed in a planar gold electrode through an alloying/dealloying process. The nanoporous electrode has an electroactive surface area up to 40 times higher than that of a flat gold electrode of the same size. The nanoporous electrode was used as a substrate to build an enzymatic electrochemical biosensor for the detection of glucose in standard samples and control serum samples. The example glucose biosensor has a linear response up to 30 mM, with a high sensitivity of 0.50 μA mM⁻¹ mm⁻², and excellent anti-interference ability against lactate, uric acid and ascorbic acid. Abundant catalyst and enzyme were stably entrapped in the nanoporous structure, leading to high stability and reproducibility of the biosensor. Development of such nanoporous structure enables the miniaturization of high-performance electrochemical biosensors for point-of-care diagnostics or environmental field testing. PMID:23208085

  14. Hybrid pore formation by directed insertion of α-haemolysin into solid-state nanopores

    NASA Astrophysics Data System (ADS)

    Hall, Adam R.; Scott, Andrew; Rotem, Dvir; Mehta, Kunal K.; Bayley, Hagan; Dekker, Cees

    2010-12-01

    Most experiments on nanopores have concentrated on the pore-forming protein α-haemolysin (αHL) and on artificial pores in solid-state membranes. While biological pores offer an atomically precise structure and the potential for genetic engineering, solid-state nanopores offer durability, size and shape control, and are also better suited for integration into wafer-scale devices. However, each system has significant limitations: αHL is difficult to integrate because it relies on delicate lipid bilayers for mechanical support, and the fabrication of solid-state nanopores with precise dimensions remains challenging. Here we show that these limitations may be overcome by inserting a single αHL pore into a solid-state nanopore. A double-stranded DNA attached to the protein pore is threaded into a solid-state nanopore by electrophoretic translocation. Protein insertion is observed in 30-40% of our attempts, and translocation of single-stranded DNA demonstrates that the hybrid nanopore remains functional. The hybrid structure offers a platform to create wafer-scale device arrays for genomic analysis, including sequencing.

  15. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  16. Threading DNA through nanopores for biosensing applications

    NASA Astrophysics Data System (ADS)

    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.

  17. Threading DNA through nanopores for biosensing applications.

    PubMed

    Fyta, Maria

    2015-07-15

    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. PMID:26061408

  18. Modelisation et simulation de pyrolyse de pneus usages dans des reacteurs de laboratoire et industriel

    NASA Astrophysics Data System (ADS)

    Lanteigne, Jean-Remi

    decomposition kinetics of pyrolysables. The simulation with data obtained in industrial operation showed the robustness of the model to predict with accuracy in transient regime, tires pyrolysis, with the help of model parameters obtained at laboratory scale, namely in regards of the trigger of production, the residence time of tires (dynamic production) and the amount of oil produced (cumulative yield). It is a novel way to model pyrolysis that could be extrapolated to new waste materials. The second objective of this doctoral research was to determine the evolution of specific tires specific heat during pyrolysis and the enthalpy of pyrolysis. The origin of this objective comes from a primary contradiction. With few exceptions, it is acknowledged that organic materials pyrolysis is globally an endothermic phenomenon. At the opposite, all experiments led with laboratory apparatuses such as DSC (Differential Scanning Calorimetry) showed exothermic peaks during dynamic experiments (constant heating rate). It has been confirmed by results obtained at the industrial scale, where no sign of exothermicity has been observed. The Hess Law has also confirmed these results, that globally, pyrolysis is indeed a completely endothermic process. An accurate energy balance is required to predict mass temperature during pyrolysis, this parameter being unbindable from kinetics. An advanced investigation of char first allowed demonstrating that specific heat of solids during pyrolysis decreases with increasing temperature until the weight loss peak is reached, around 400°C, and then starts increasing again. This observation, combined with the fact that the sample loses weight during pyrolysis is considered as the major cause of the apparition of an exothermic peak in laboratory scale experiments. That is, the control system of these apparatuses generates a bias and an unavoidable overheat of the samples producing this exothermic behavior. It would thus be an artifact. On the base of new data

  19. Controlled nanoporous Pt morphologies by varying deposition parameters

    SciTech Connect

    Misra, Amit; Nastasi, Michael A; Baldwin, J Kevin; Goodwin, Peter M; Bhattacharyya, Dhriti; Antoniou, Antonia

    2009-01-01

    Typically, dealloying of an alloy can result in an open cell nanoporous structure of the least electrochemically active element. Here, we show that a wider range of nanoporous structures is possible by controlling the composition and deposition parameters of the as-synthesized alloy as a way to provide sites for preferential etching. We demonstrate this by synthesizing nanoporous platinum (np-Pt) through electrochemical dealloying in aqueous HF from co-sputtered Pt{sub x}Si{sub 1-x} amorphous films. For increased Pt fraction of the amorphous alloy, silicon dissolution is favored along pre-existing features of the amorphous film (e.g. column boundaries or surface asperities). The resulting np-Pt depends on the manner in which silicon is preferentially removed. In addition to the expected isotropic open cell structure, columnar and Voronoi (radial) np-Pt are observed. A processing-structure map is developed to correlate np-Pt morphology to the initial composition and thickness of the amorphous Pt{sub x}Si{sub 1-x} film and the negative substrate bias used in magnetron sputtering.

  20. Single-crystalline nanoporous Nb2O5 nanotubes

    PubMed Central

    2011-01-01

    Single-crystalline nanoporous Nb2O5 nanotubes were fabricated by a two-step solution route, the growth of uniform single-crystalline Nb2O5 nanorods and the following ion-assisted selective dissolution along the [001] direction. Nb2O5 tubular structure was created by preferentially etching (001) crystallographic planes, which has a nearly homogeneous diameter and length. Dense nanopores with the diameters of several nanometers were created on the shell of Nb2O5 tubular structures, which can also retain the crystallographic orientation of Nb2O5 precursor nanorods. The present chemical etching strategy is versatile and can be extended to different-sized nanorod precursors. Furthermore, these as-obtained nanorod precursors and nanotube products can also be used as template for the fabrication of 1 D nanostructured niobates, such as LiNbO3, NaNbO3, and KNbO3. PMID:21711650

  1. Single-crystalline nanoporous Nb2O5 nanotubes.

    PubMed

    Liu, Jun; Xue, Dongfeng; Li, Keyan

    2011-01-01

    Single-crystalline nanoporous Nb2O5 nanotubes were fabricated by a two-step solution route, the growth of uniform single-crystalline Nb2O5 nanorods and the following ion-assisted selective dissolution along the [001] direction. Nb2O5 tubular structure was created by preferentially etching (001) crystallographic planes, which has a nearly homogeneous diameter and length. Dense nanopores with the diameters of several nanometers were created on the shell of Nb2O5 tubular structures, which can also retain the crystallographic orientation of Nb2O5 precursor nanorods. The present chemical etching strategy is versatile and can be extended to different-sized nanorod precursors. Furthermore, these as-obtained nanorod precursors and nanotube products can also be used as template for the fabrication of 1 D nanostructured niobates, such as LiNbO3, NaNbO3, and KNbO3. PMID:21711650

  2. Oscillation of Capacitance inside Nanopores

    SciTech Connect

    Jiang, De-en; Jin, Zhehui; Wu, Jianzhong

    2011-10-26

    Porous carbons of high surface area are promising as cost-effective electrode materials for supercapacitors. Although great attention has been given to the anomalous increase of the capacitance as the pore size approaches the ionic dimensions, there remains a lack of full comprehension of the size dependence of the capacitance in nanopores. Here we predict from a classical density functional theory that the capacitance of an ionic-liquid electrolyte inside a nanopore oscillates with a decaying envelope as the pore size increases. The oscillatory behavior can be attributed to the interference of the overlapping electric double layers (EDLs); namely, the maxima in capacitance appear when superposition of the two EDLs is most constructive. The theoretical prediction agrees well with the experiment when the pore size is less than twice the ionic diameter. Confirmation of the entire oscillatory spectrum invites future experiments with a precise control of the pore size from micro- to mesoscales.

  3. Oscillation of Capacitance inside Nanopores

    SciTech Connect

    Jiang, Deen; Wu, Jianzhong; Jin, Zhehui

    2011-01-01

    materials for supercapacitors. Although great attention has been given to the anomalous increase of the capacitance as the pore size approaches the ionic dimensions, there remains a lack of full comprehension of the size dependence of the capacitance in nanopores. Here we predict from a classical density functional theory that the capacitance of an ionic-liquid electrolyte inside a nanopore oscillates with a decaying envelope as the pore size increases. The oscillatory behavior can be attributed to the interference of the overlapping electric double layers (EDLs); namely, the maxima in capacitance appear when superposition of the two EDLs is most constructive. The theoretical prediction agreeswell with the experiment when the pore size is less than twice the ionic diameter.Confirmation of the entire oscillatory spectruminvites future experiments with a precise control of the pore size from micro- to mesoscales.

  4. Electrochemical annealing of nanoporous gold by application of cyclic potential sweeps

    PubMed Central

    Sharma, Abeera; Bhattarai, Jay K.; Alla, Allan J.; Demchenko, Alexei V.; Stine, Keith J.

    2015-01-01

    An electrochemical method for annealing the pore sizes of nanoporous gold is reported. The pore sizes of nanoporous gold can be increased by electrochemical cycling with the upper potential limit being just at the onset of gold oxide formation. This study has been performed in electrolyte solutions including potassium chloride, sodium nitrate and sodium perchlorate. Scanning electron microscopy images have been used for ligament and pore size analysis. We examine the modifications of nanoporous gold due to annealing using electrochemical impedance spectroscopy, and cyclic voltammetry and offer a comparison of the surface coverage using the gold oxide stripping method as well as the method in which electrochemically accessible surface area is determined by using a diffusing redox probe. The effect of additives adsorbed on the nanoporous gold surface when subjected to annealing in different electrolytes as well as the subsequent structural changes in nanoporous gold are also reported. The effect of the annealing process on the application of nanoporous gold as a substrate for glucose electro-oxidation is briefly examined. PMID:25649027

  5. Noncovalent functionalization of solid-state nanopores via self-assembly of amphipols.

    PubMed

    Pérez-Mitta, Gonzalo; Burr, Loïc; Tuninetti, Jimena S; Trautmann, Christina; Toimil-Molares, María Eugenia; Azzaroni, Omar

    2016-01-21

    In recent years there has been increasing interest in the development of new methods for conferring functional features to nanopore-based fluidic devices. In this work, we describe for the first time the noncovalent integration of amphoteric-amphipathic polymers, also known as "amphipols", into single conical nanopores in order to obtain signal-responsive chemical nanodevices. Highly-tapered conical nanopores were fabricated by single-sided chemical etching of polycarbonate foils. After etching, the surface of the conical nanopores was chemically modified, by first metallizing the surface via gold sputtering and then by amphiphilic self-assembly of the amphipol. The net charge of adsorbed amphipols was regulated via pH changes under the environmental conditions. The pH-dependent chemical equilibrium of the weak acidic and basic monomers facilitates the regulation of the ionic transport through the nanopore by adjusting the pH of the electrolyte solution. Our results demonstrate that functional amphipathic polymers are powerful building blocks for the surface modification of nanopores and might ultimately pave the way to a new means of integrating functional and/or responsive units within nanofluidic structures. PMID:26676314

  6. Switchable imbibition in nanoporous gold

    PubMed Central

    Xue, Yahui; Markmann, Jürgen; Duan, Huiling; Weissmüller, Jörg; 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 host geometry, 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, that is, 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 transport in the metallic nanopores. 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. PMID:24980062

  7. Switchable imbibition in nanoporous gold

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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 host geometry, 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, that is, 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 transport in the metallic nanopores. 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.

  8. Entrapping Enzyme in a Functionalized Nanoporous Support

    SciTech Connect

    Lei, Chenghong; Shin, Yongsoon; Liu, Jun; Ackerman, Eric J.

    2002-09-25

    The enzyme organophosphorus hydrolase (OPH) was spontaneously entrapped in carboxylethyl- or aminopropyl-functionalized mesoporous silica with rigid, uniform open-pore geometry (30 nm). This approach yielded larger amounts of protein loading and much higher specific activity of the enzyme when compared to the unfunctionalized mesoporous silica and normal porous silica with the same pore size. When OPH was incubated with the functionalized mesoporous silica, protein molecules were sequestered in or excluded from the porous material, depending on electrostatic interaction with the charged functional groups. OPH entrapped in the organically functionalized nanopores showed an exceptional high immobilization efficiency of more than 200% and enhanced stability far exceeding that of the free enzyme in solution. The combination of high protein loading, high immobilization efficiency and stability is attributed to the large and uniform pore structure, and to the optimum environment introduced by the functional groups.

  9. Anomalous retroreflection from strongly absorbing nanoporous semiconductors.

    PubMed

    Prislopski, S Ya; Naumenko, E K; Tiginyanu, I M; Ghimpu, L; Monaico, E; Sirbu, L; Gaponenko, S V

    2011-08-15

    Pronounced retroreflection behavior is reported for a fishnet nanoporous strongly absorbing semiconductor material. Retroreflection features a half-cone about 0.35 rad along with diffusive specular reflection for all angles of incidence. Retroreflection is apparent by the naked eye with daylight illumination and exhibits no selectivity with respect to wavelength and polarization of incident light featuring minor depolarization of retroreflected light. The reflectance in the backward direction measures 12% with respect to a white scattering etalon. The phenomenon can be classified neither as coherent backscattering nor as Anderson localization of light. The primary model includes light scattering from strongly absorptive and refractive superwavelength clusters existing within the porous fishnet structure. A reasonable qualitative explanation is based on the fact that strict retroreflection obeys shorter paths inside absorbing medium, whereas all alternative paths will lead to stronger absorption of light. PMID:21847216

  10. Nanoporous membranes for medical and biological applications

    PubMed Central

    Adiga, Shashishekar P; Jin, Chunmin; Curtiss, Larry A; Monteiro-Riviere, Nancy A.; Narayan, Roger J

    2013-01-01

    Synthetic nanoporous materials have numerous potential biological and medical applications that involve sorting, sensing, isolating and releasing biological molecules. Nanoporous systems engineered to mimic natural filtration systems are actively being developed for use in smart implantable drug delivery systems, bioartificial organs, and other novel nano-enabled medical devices. Recent advances in nanoscience have made it possible to precisely control the morphology as well as physical and chemical properties of the pores in nanoporous materials that make them increasingly attractive for regulating and sensing transport at the molecular level. In this work, an overview of nanoporous membranes for biomedical applications is given. Various in vivo and in vitro membrane applications, including biosensing, biosorting, immunoisolation and drug delivery, are presented. Different types of nanoporous materials and their fabrication techniques are discussed with an emphasis on membranes with ordered pores. Desirable properties of membranes used in implantable devices, including biocompatibility and antibiofouling behavior, are discussed. The use of surface modification techniques to improve the function of nanoporous membranes is reviewed. Despite the extensive research carried out in fabrication, characterization, and modeling of nanoporous materials, there are still several challenges that must be overcome in order to create synthetic nanoporous systems that behave similarly to their biological counterparts. PMID:20049818

  11. Method to fabricate functionalized conical nanopores

    DOEpatents

    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. Modeling of the bioactivated nanopore devices.

    PubMed

    Talasaz, AmirAli H; Liu, Yang; Ronaghi, Mostafa; Davis, Ronald W

    2006-01-01

    This paper presents the modeling of the electrical properties of bioactivated nanopores, customized nanopore devices with a biological macromolecule attached in the pore as the probe. These devices are capable of detecting and analyzing interactions between the attached biomolecule and the molecules in the analyte at a single molecule level. PMID:17946483

  13. Enhancing nanopore sensing with DNA nanotechnology

    NASA Astrophysics Data System (ADS)

    Keyser, Ulrich F.

    2016-02-01

    Nanopores are on the brink of fundamentally changing DNA sequencing. At the same time, DNA origami provides unprecedented freedom in molecular design. Here, I suggest why a combination of solid-state nanopores and DNA nanotechnology will lead to exciting new experiments.

  14. Nanopore DNA sequencing with MspA.

    PubMed

    Derrington, Ian M; Butler, Tom Z; Collins, Marcus D; Manrao, Elizabeth; Pavlenok, Mikhail; Niederweis, Michael; Gundlach, Jens H

    2010-09-14

    Nanopore sequencing has the potential to become a direct, fast, and inexpensive DNA sequencing technology. The simplest form of nanopore DNA sequencing utilizes the hypothesis that individual nucleotides of single-stranded DNA passing through a nanopore will uniquely modulate an ionic current flowing through the pore, allowing the record of the current to yield the DNA sequence. We demonstrate that the ionic current through the engineered Mycobacterium smegmatis porin A, MspA, has the ability to distinguish all four DNA nucleotides and resolve single-nucleotides in single-stranded DNA when double-stranded DNA temporarily holds the nucleotides in the pore constriction. Passing DNA with a series of double-stranded sections through MspA provides proof of principle of a simple DNA sequencing method using a nanopore. These findings highlight the importance of MspA in the future of nanopore sequencing. PMID:20798343

  15. Single Nanopore Investigations with Ion Conductance Microscopy

    PubMed Central

    Chen, Chiao-Chen; Zhou, Yi; Baker, Lane A.

    2011-01-01

    A three-electrode scanning ion conductance microscope (SICM) was used to investigate the local current-voltage properties of a single nanopore. In this experimental configuration, the response measured is a function of changes in the resistances involved in the pathways of ion migration. Single nanopore membranes utilized in this study were prepared with an epoxy painting procedure to isolate a single nanopore from a track-etch multi-pore membrane. Current-voltage responses measured with the SICM probe in the vicinity of a single nanopore were investigated in detail and agreed well with equivalent circuit models proposed in this study. With this modified SICM, the current-voltage responses characterized for the case of a single cylindrical pore and a single conical pore exhibit distinct conductance properties that originate from the geometry of nanopores. PMID:21923184

  16. Nanopore DNA sequencing with MspA

    PubMed Central

    Derrington, Ian M.; Butler, Tom Z.; Collins, Marcus D.; Manrao, Elizabeth; Pavlenok, Mikhail; Niederweis, Michael; Gundlach, Jens H.

    2010-01-01

    Nanopore sequencing has the potential to become a direct, fast, and inexpensive DNA sequencing technology. The simplest form of nanopore DNA sequencing utilizes the hypothesis that individual nucleotides of single-stranded DNA passing through a nanopore will uniquely modulate an ionic current flowing through the pore, allowing the record of the current to yield the DNA sequence. We demonstrate that the ionic current through the engineered Mycobacterium smegmatis porin A, MspA, has the ability to distinguish all four DNA nucleotides and resolve single-nucleotides in single-stranded DNA when double-stranded DNA temporarily holds the nucleotides in the pore constriction. Passing DNA with a series of double-stranded sections through MspA provides proof of principle of a simple DNA sequencing method using a nanopore. These findings highlight the importance of MspA in the future of nanopore sequencing. PMID:20798343

  17. Integration and characterization of SiN nanopores for single-molecule detection in liquid-core ARROW waveguides

    NASA Astrophysics Data System (ADS)

    Rudenko, M. I.; Yin, D.; Holmes, M.; Hawkins, A. R.; Schmidt, H.

    2007-02-01

    We demonstrate a method for integrating silicon nitride nanopores in liquid core Anti Resonant Reflecting Optical Waveguides (ARROW) for single molecule electrical detection and control. We use a two-step integration process when a micropore is fabricated first, paving the way for subsequent nanopore integration in the first silicon nitride layer of the ARROW structure. Nanopores with dimensions as small as 11 nm were fabricated using a Focused Ion Beam shrinking process commensurate with single particle gating of viruses, proteins, ribosomes and other biomolecules.

  18. Oxygen Reduction at Very Low Overpotential on Nanoporous Ag Catalysts

    SciTech Connect

    Zhou, Yang; Lu, Qi; Zhuang, Zhongbin; Hutchings, Gregory S.; Kattel, Shyam; Yan, Yushan; Chen, Jingguang G.; Xiao, John Q.; Jiao, Feng

    2015-05-07

    Here we report a monolithic nanoporous Ag (np-Ag) material, synthesized using the dealloying method, as high-performance catalysts for ORR in alkaline media. As shown in Scheme 1, when there is insufficient potential input, the O2 molecules are more likely to rebound off from a planar electrode surface (i.e. bulk polycrystalline metal, films made from nanoparticles or nanowires) before they could be reduced. In contrast, they are more likely to be trapped inside the monolithic nanoporous structure, contacting with catalytic surface for multiple time, which greatly enhances the chance for them to be fully reduced. As a result, the np-Ag catalyst is able to achieve an equivalent or better ORR performance than the state-of the-art Pt/C catalyst at low overpotentials, which is most desired in electrochemical energy applications for maximizing efficiency.

  19. Piezoelectric and dielectric properties of nanoporous polyvinylidence fluoride (PVDF) films

    NASA Astrophysics Data System (ADS)

    Zhao, Ping; Wang, Shifa; Kadlec, Alec

    2016-04-01

    A nanoporous polyvinylidene Fluoride (PVDF) thin film was developed for applications in energy harvesting, medical surgeries, and industrial robotics. This sponge-like nanoporous PVDF structure dramatically enhanced the piezoelectric effect because it yielded considerably large deformation under a small force. A casting-etching method was adopted to make films, which is effective to control the porosity, flexibility, and thickness of the film. The films with various Zinc Oxide (ZnO) mass fractions ranging from 10 to 50% were fabricated to investigate the porosity effect. The piezoelectric coefficient d33 as well as dielectric constant and loss of the films were characterized. The results were analyzed and the optimal design of the film with the right amount of ZnO nanoparticles was determined.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Oxygen Reduction at Very Low Overpotential on Nanoporous Ag Catalysts

    DOE PAGESBeta

    Zhou, Yang; Lu, Qi; Zhuang, Zhongbin; Hutchings, Gregory S.; Kattel, Shyam; Yan, Yushan; Chen, Jingguang G.; Xiao, John Q.; Jiao, Feng

    2015-05-07

    Here we report a monolithic nanoporous Ag (np-Ag) material, synthesized using the dealloying method, as high-performance catalysts for ORR in alkaline media. As shown in Scheme 1, when there is insufficient potential input, the O2 molecules are more likely to rebound off from a planar electrode surface (i.e. bulk polycrystalline metal, films made from nanoparticles or nanowires) before they could be reduced. In contrast, they are more likely to be trapped inside the monolithic nanoporous structure, contacting with catalytic surface for multiple time, which greatly enhances the chance for them to be fully reduced. As a result, the np-Ag catalystmore » is able to achieve an equivalent or better ORR performance than the state-of the-art Pt/C catalyst at low overpotentials, which is most desired in electrochemical energy applications for maximizing efficiency.« less

  2. Evaporation of sessile droplets on nano-porous alumina surfaces

    NASA Astrophysics Data System (ADS)

    Singh, Sanchit K.; Pratap, Dheeraj; Ramakrishna, S. Anantha; Khanderkar, Sameer

    2013-07-01

    An experimental investigation of evaporation of sessile droplets is presented on nano-porous alumina surfaces with different pore distribution morphologies and pore sizes. Evaporation can be considered as a quasi-steady-state process, such that the vapor concentration distribution above the droplet satisfies the Laplace equation, but with a timevarying droplet surface. For benchmarking, the evaporation of sessile water and ethanol droplets is also investigated on standard borosilicate glass and Teflon surfaces respectively, and results are compared with the previous work. Contact angle variation with time is also recorded and high speed videos showing the spreading process of droplets on nanoporous surfaces are taken. The results clearly show that nano-structuring is an effective tool to control wettability as well as the diffusive evaporation process.

  3. Radiative Properties of Silica Nanoporous Matrices

    NASA Astrophysics Data System (ADS)

    Lallich, Sylvain; Enguehard, Franck; Baillis, Dominique

    2008-08-01

    Superinsulating materials are currently of much interest because of the price of energy on the one hand and CO2 emissions attributed to offices and houses cooling and heating on the other hand. In this work, we aim at understanding and modeling the radiative transfer within silica nanoporous matrices that are the principal components of nanoporous superinsulating materials. We first elaborate samples of various thicknesses from a pyrogenic silica powder. These samples are characterized using two spectrophotometers on the whole wavelength range [250 nm; 20 μm]. Using a parameter identification technique, we compute the radiative properties of the various samples. Then, our samples being made of packed quasi-spherical particles, we use the Mie theory to model the radiative properties of these materials. Due to the observed discrepancies between the experimental radiative properties and those computed from the Mie theory with a uniform value of 10 nm for the scatterer diameter (value derived from TEM images), we determine an effective scatterer diameter that allows a good agreement between the experimental radiative properties and the Mie results. Nevertheless, in the short wavelength range, the Mie theory gives results that significantly differ from the experimental radiative properties. This behavior is attributed to structure effects as the wavelength is of the same order of magnitude as the diameter of the scatterer that is now regarded as an aggregate of nanoparticles. Hence, to take into account these effects, we use the discrete dipole approximation (DDA). The DDA extinction coefficient spectra appear to be much closer to the experimental results than the Mie spectra, and these first results are quite encouraging.

  4. On the microstructure of nanoporous gold: an x-ray diffraction study

    SciTech Connect

    Van Petegem, S; Brandstetter, S; Maa?, R; Schmitt, B; Borca, C; Van Swygenhoven, H; Hodge, A M; El-Dasher, B S; Biener, J

    2008-08-26

    The evolution of the grain structure, internal stresses, and the lattice misorientations of nanoporous gold (npAu) during dealloying of bulk (3D) Ag-Au alloy samples was studied by various in-situ and ex-situ X-ray diffraction techniques including powder and Laue diffraction. The experiments reveal that the dealloying process preserves the original crystallographic structure, but leads to a small spread in orientations within individual grains. Furthermore, most grains develop in-plane tensile stress. The feature size of the developing nanoporous structure increases with increasing dealloying time.

  5. Localization Transport in Granular and Nanoporous Carbon Systems.

    NASA Astrophysics Data System (ADS)

    Fung, Alex Weng Pui

    Porous carbon materials have long since been used in industry to make capacitors and adsorption agents because of their high specific surface area. Although their adsorption properties have been extensively studied, we have not seen the same vigor in the investigation of their physical properties, which are important not only for providing complementary characterization methods, but also for understanding the physics which underlies the manufacturing process and motivates intelligent design of these materials. The study of the new physics in these novel nanoporous materials also straddles the scientific forefronts of nanodimensional and disordered systems. In this thesis, we study the structural and electrical properties of two nanoporous carbons, namely activated carbon fibers and carbon aerogels. Specifically, we perform Raman scattering, x-ray diffraction, magnetic susceptibility, electrical transport and magnetotransport experiments. Results from other experiments reported in the literature or communicated to us by our collaborators, such as porosity and surface area measurements by adsorption methods, electron spin resonance, transmission electron microscopy, mechanical properties measurements and so on, are also frequently used in this thesis for additional characterization information. By correlating all the relevant results, we obtain the structure -property relationships in these nanoporous materials. This study shows that the transport properties of these porous materials can be used on one hand for sensitive characterization of complex materials, and on the other hand, for observing interesting and unusual physical phenomena. For example, as-prepared nanoporous carbon systems, exhibit in their low-temperature electrical conductivity a universal temperature dependence which is characteristic of a granular metallic system, despite their morphological differences. By studying further the magnetoresistance in these carbon materials, it is found that the

  6. Effect of Fabrication-Dependent Shape and Composition of Solid-State Nanopores on Single Nanoparticle Detection

    PubMed Central

    Liu, Shuo; Yuzvinsky, Thomas D.; Schmidt, Holger

    2013-01-01

    Solid-state nanopores can be fabricated in a variety of ways and form the basis for label-free sensing of single nanoparticles: as individual nanoparticles traverse the nanopore, they alter the ionic current across it in a characteristic way. Typically, nanopores are described by the diameter of their limiting aperture, and less attention has been paid to other, fabrication-dependent parameters. Here, we report a comprehensive analysis of the properties and sensing performance of three types of nanopore with identical 50nm aperture, but fabricated using three different techniques: direct ion beam milling, ion beam sculpting, and electron beam sculpting. The nanopores differ substantially in physical shape and chemical composition as identified by ion-beam assisted cross sectioning and energy dispersive x-ray spectroscopy. Concomitant differences in electrical sensing of single 30nm beads, such as variations in blockade depth, duration, and electric field dependence, are observed and modeled using hydrodynamic simulations. The excellent agreement between experiment and physical modeling shows that the physical properties (shape) and not the chemical surface composition determine the sensing performance of a solid-state nanopore in the absence of deliberate surface modification. Consequently, nanoparticle sensing performance can be accurately predicted once the full three dimensional structure of the nanopore is known. PMID:23697604

  7. The nanostructure effect on the adhesion and growth rates of epithelial cells with well-defined nanoporous alumina substrates.

    PubMed

    Chung, S H; Son, S J; Min, J

    2010-03-26

    We systematically analyzed the adhesion and the proliferation of cells on various nanoporous alumina surfaces to understand the effects of nanostructured surfaces on cell behavior. Various nanoporous surfaces were fabricated using the anodizing method and characterized by atomic force microscopy and scanning electron microscopy. The adhesion rate and proliferation rate of cells as functions of pore size and depth were statistically investigated using a colorimetric method. The adhesion rate of cells was not affected by the depth of the nanoporous surface whereas the proliferation of cells dramatically increased when the aspect ratio of the nanopore was near unity. This phenomenon was further verified by comparing the change in roughness of the cytoplasmic layer of cells adhered on a nanoporous surface with that of a bare nanoporous surface. The proliferation of cells was also influenced by the pore size of the nanoporous surface because the nanostructure could control the interaction between extracellular matrix (ECM) molecules and the surface. In conclusion, the nanostructured surfaces affected cell adhesion and proliferation by increasing the surface area to which the cells could adhere, and the interactions between small ECM molecules were influenced by the sufficiently small structures of the nanosurface. PMID:20195010

  8. Non-Faradaic Energy Storage by Room Temperature Ionic Liquids in Nanoporous Electrodes.

    PubMed

    Vatamanu, Jenel; Vatamanu, Mihaela; Bedrov, Dmitry

    2015-06-23

    The enhancement of non-Faradaic charge and energy density stored by ionic electrolytes in nanostructured electrodes is an intriguing issue of great practical importance for energy storage in electric double layer capacitors. On the basis of extensive molecular dynamics simulations of various carbon-based nanoporous electrodes and room temperature ionic liquid (RTIL) electrolytes, we identify atomistic mechanisms and correlations between electrode/electrolyte structures that lead to capacitance enhancement. In the symmetric electrode setup with nanopores having atomically smooth walls, most RTILs showed up to 50% capacitance increase compared to infinitely wide pore. Extensive simulations using asymmetric electrodes and pores with atomically rough surfaces demonstrated that tuning of electrode nanostructure could lead to further substantial capacitance enhancement. Therefore, the capacitance in nanoporous electrodes can be increased due to a combination of two effects: (i) the screening of ionic interactions by nanopore walls upon electrolyte nanoconfinement, and (ii) the optimization of nanopore structure (volume, surface roughness) to take into account the asymmetry between cation and anion chemical structures. PMID:26038979

  9. Phosphonate-Derived Nanoporous Metal Phosphates and Their Superior Energy Storage Application.

    PubMed

    Pramanik, Malay; Salunkhe, Rahul R; Imura, Masataka; Yamauchi, Yusuke

    2016-04-20

    Nanoporous nickel, aluminum, and zirconium phosphates (hereafter, abbreviated as NiP, AlP, and ZrP, respectively) with high surface areas and controlled morphology and crystallinity have been synthesized through simple calcination of the corresponding phosphonates. For the preparation of phosphonate materials, nitrilotris(methylene)triphosphonic acid (NMPA) is used as phosphorus source. The organic component in the phosphonate materials is thermally removed to form nanoporous structures in the final phosphate materials. The formation mechanism of nanoporous structures, as well as the effect of applied calcination temperatures on the morphology and crystallinity of the final phosphate materials, is carefully discussed. Especially, nanoporous NiP materials have a spherical morphology with a high surface area and can have great applicability as an electrode material for supercapacitors. It has been found that there is a critical effect of particle sizes, surface areas, and the crystallinities of NiP materials toward electrochemical behavior. Our nanoporous NiP material has superior specific capacitance, as compared to various phosphate nanomaterials reported previously. Excellent retention capacity of 97% is realized even after 1000 cycles, which can be ascribed to its high structural stability. PMID:27028363

  10. The Core-Shell Approach to Formation of Ordered Nanoporous Materials

    SciTech Connect

    Chang, Jeong H.; Wang, Li Q.; Shin, Yongsoon; Jeong, Byeongmoon; Birnbaum, Jerome C.; Exarhos, Gregory J.

    2002-03-04

    This work describes a novel core-shell approach for the preparation of ordered nanoporous ceramic materials that involve a self-assembly process at the molecular level using MPEG-b-PDLLA bloack copolymers. This approach provides for rapid self-assembly and structural reorganization at room temperature. Selected MPEG-b-PDLLA block copolymers were synthesized with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. This allows the micelle size to be systematically varied. Results from this work are used to understand the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates. The core-shell mechanism for nanoporous structure evolution is based on the size and contrasting micellar packing arrangements that are controlled by the copolymer.

  11. Precise electrochemical fabrication of sub-20 nm solid-state nanopores for single-molecule biosensing

    NASA Astrophysics Data System (ADS)

    Ayub, Mariam; Ivanov, Aleksandar; Hong, Jongin; Kuhn, Phillip; Instuli, Emanuele; Edel, Joshua B.; Albrecht, Tim

    2010-11-01

    It has recently been shown that solid-state nanometer-scale pores ('nanopores') can be used as highly sensitive single-molecule sensors. For example, electrophoretic translocation of DNA, RNA and proteins through such nanopores has enabled both detection and structural analysis of these complex biomolecules. Control over the nanopore size is critical as the pore must be comparable in size to the analyte molecule in question. The most widely used fabrication methods are based on focused electron or ion beams and thus require (scanning) transmission electron microscopy and focused ion beam (FIB) instrumentation. Even though very small pores have been made using these approaches, several issues remain. These include the requirement of being restricted to rather thin, mechanically less stable membranes, particularly for pore diameters in the single-digit nanometer range, lack of control of the surface properties at and inside the nanopore, and finally, the fabrication cost. In the proof-of-concept study, we report on a novel and simple route for fabricating metal nanopores with apparent diameters below 20 nm using electrodeposition and real-time ionic current feedback in solution. This fabrication approach inserts considerable flexibility into the kinds of platforms that can be used and the nanopore membrane material. Starting from much larger pores, which are straightforward to make using FIB or other semiconductor fabrication methods, we electrodeposit Pt at the nanopore interface while monitoring its ionic conductance at the same time in a bi-potentiostatic setup. Due to the deposition of Pt, the nanopore decreases in size, resulting in a decrease of the pore conductance. Once a desired pore conductance has been reached, the electrodeposition process is stopped by switching the potential of the membrane electrode and the fabrication process is complete. Furthermore, we demonstrate that these pores can be used for single-biomolecule analysis, such as that of

  12. Quantized ionic conductance in nanopores.

    PubMed

    Zwolak, Michael; Lagerqvist, Johan; Di Ventra, Massimiliano

    2009-09-18

    Ionic transport in nanopores is a fundamentally and technologically important problem in view of its occurrence in biological processes and its impact on novel DNA sequencing applications. Using molecular dynamics simulations we show that ion transport may exhibit strong nonlinearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. We discuss this phenomenon and the conditions under which it should be experimentally observable. PMID:19792463

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

    PubMed

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

    2013-04-19

    High-bandwidth and low-noise nanopore sensor and detection electronics are crucial in achieving single-DNA-base resolution. A potential way to accomplish this goal is to integrate solid-state nanopores within a CMOS platform, in close proximity to the biasing electrodes and custom-designed amplifier electronics. Here we report the integration of solid-state nanopore devices in a commercial complementary metal-oxide-semiconductor (CMOS) potentiostat chip implemented in On-Semiconductor's 0.5 μm technology. Nanopore membranes incorporating electrodes are fabricated by post-CMOS micromachining utilizing the n+ polysilicon/SiO2/n+ polysilicon capacitor structure available in the aforementioned process. Nanopores are created in the CMOS process by drilling in a transmission electron microscope and shrinking by atomic layer deposition. We also describe a batch fabrication method to process a large of number of electrode-embedded nanopores with sub-10 nm diameter across CMOS-compatible wafers by electron beam lithography and atomic layer deposition. The CMOS-compatibility of our fabrication process is verified by testing the electrical functionality of on-chip circuitry. We observe high current leakage with the CMOS nanopore devices due to the ionic diffusion through the SiO2 membrane. To prevent this leakage, we coat the membrane with Al2O3, which acts as an efficient diffusion barrier against alkali ions. The resulting nanopore devices also exhibit higher robustness and lower 1/f noise as compared to SiO2 and SiNx. Furthermore, we propose a theoretical model for our low-capacitance CMOS nanopore devices, showing good agreement with the experimental value. In addition, experiments and theoretical models of translocation studies are presented using 48.5 kbp λ-DNA in order to prove the functionality of on-chip pores coated with Al2O3. PMID:23519330

  14. Integration of solid-state nanopores in a 0.5 μm cmos foundry process

    PubMed Central

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

    2013-01-01

    High-bandwidth and low-noise nanopore sensor and detection electronics are crucial in achieving single-DNA base resolution. A potential way to accomplish this goal is to integrate solid-state nanopores within a CMOS platform, in close proximity to the biasing electrodes and custom-designed amplifier electronics. Here we report the integration of solid-state nanopore devices in a commercial complementary metal-oxide semiconductor (CMOS) potentiostat chip implemented in On-Semiconductor’s 0.5 μm technology. Nanopore membranes incorporating electrodes are fabricated by post-CMOS micromachining utilizing the N+ polysilicon/SiO2/N+ polysilicon capacitor structure available in the aforementioned process. Nanopores are created in the CMOS process by drilling in a transmission electron microscope and shrinking by atomic layer deposition. We also describe a batch fabrication method to process a large of number of electrode-embedded nanopores with sub-10 nm diameter across CMOS-compatible wafers by electron beam lithography and atomic layer deposition. The CMOS-compatibility of our fabrication process is verified by testing the electrical functionality of on-chip circuitry. We observe high current leakage with the CMOS nanopore devices due to the ionic diffusion through the SiO2 membrane. To prevent this leakage, we coat the membrane with Al2O3 which acts as an efficient diffusion barrier against alkali ions. The resulting nanopore devices also exhibit higher robustness and lower 1/f noise as compared to SiO2 and SiNx. Furthermore, we propose a theoretical model for our low-capacitance CMOS nanopore devices, showing good agreement with the experimental value. In addition, experiments and theoretical models of translocation studies are presented using 48.5 kbp λ-DNA in order to prove the functionality of on-chip pores coated with Al2O3. PMID:23519330

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  16. Optimizing nanoporous materials for gas storage.

    PubMed

    Simon, Cory M; Kim, Jihan; Lin, Li-Chiang; Martin, Richard L; Haranczyk, Maciej; Smit, Berend

    2014-03-28

    In this work, we address the question of which thermodynamic factors determine the deliverable capacity of methane in nanoporous materials. The deliverable capacity is one of the key factors that determines the performance of a material for methane storage in automotive fuel tanks. To obtain insights into how the molecular characteristics of a material are related to the deliverable capacity, we developed several statistical thermodynamic models. The predictions of these models are compared with the classical thermodynamics approach of Bhatia and Myers [Bhatia and Myers, Langmuir, 2005, 22, 1688] and with the results of molecular simulations in which we screen the International Zeolite Association (IZA) structure database and a hypothetical zeolite database of over 100,000 structures. Both the simulations and our models do not support the rule of thumb that, for methane storage, one should aim for an optimal heat of adsorption of 18.8 kJ mol(-1). Instead, our models show that one can identify an optimal heat of adsorption, but that this optimal heat of adsorption depends on the structure of the material and can range from 8 to 23 kJ mol(-1). The different models we have developed are aimed to determine how this optimal heat of adsorption is related to the molecular structure of the material. PMID:24394864

  17. Nano-porous calcium phosphate balls.

    PubMed

    Kovach, Ildyko; Kosmella, Sabine; Prietzel, Claudia; Bagdahn, Christian; Koetz, Joachim

    2015-08-01

    By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. PMID:26052107

  18. Nanoporous ultra-high specific surface inorganic fibres

    NASA Astrophysics Data System (ADS)

    Kanehata, Masaki; Ding, Bin; Shiratori, Seimei

    2007-08-01

    Nanoporous inorganic (silica) nanofibres with ultra-high specific surface have been fabricated by electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and colloidal silica nanoparticles, followed by selective removal of the PVA component. The configurations of the composite and inorganic nanofibres were investigated by changing the average silica particle diameters and the concentrations of colloidal silica particles in polymer solutions. After the removal of PVA by calcination, the fibre shape of pure silica particle assembly was maintained. The nanoporous silica fibres were assembled as a porous membrane with a high surface roughness. From the results of Brunauer-Emmett-Teller (BET) measurements, the BET surface area of inorganic silica nanofibrous membranes was increased with the decrease of the particle diameters. The membrane composed of silica particles with diameters of 15 nm showed the largest BET surface area of 270.3 m2 g-1 and total pore volume of 0.66 cm3 g-1. The physical absorption of methylene blue dye molecules by nanoporous silica membranes was examined using UV-vis spectrometry. Additionally, the porous silica membranes modified with fluoroalkylsilane showed super-hydrophobicity due to their porous structures.

  19. Quasithermodynamic Contributions to the Fluctuations of a Protein Nanopore

    PubMed Central

    2015-01-01

    Proteins undergo thermally activated conformational fluctuations among two or more substates, but a quantitative inquiry on their kinetics is persistently challenged by numerous factors, including the complexity and dynamics of various interactions, along with the inability to detect functional substates within a resolvable time scale. Here, we analyzed in detail the current fluctuations of a monomeric β-barrel protein nanopore of known high-resolution X-ray crystal structure. We demonstrated that targeted perturbations of the protein nanopore system, in the form of loop-deletion mutagenesis, accompanying alterations of electrostatic interactions between long extracellular loops, produced modest changes of the differential activation free energies calculated at 25 °C, ΔΔG⧧, in the range near the thermal energy but substantial and correlated modifications of the differential activation enthalpies, ΔΔH⧧, and entropies, ΔΔS⧧. This finding indicates that the local conformational reorganizations of the packing and flexibility of the fluctuating loops lining the central constriction of this protein nanopore were supplemented by changes in the single-channel kinetics. These changes were reflected in the enthalpy–entropy reconversions of the interactions between the loop partners with a compensating temperature, TC, of ∼300 K, and an activation free energy constant of ∼41 kJ/mol. We also determined that temperature has a much greater effect on the energetics of the equilibrium gating fluctuations of a protein nanopore than other environmental parameters, such as the ionic strength of the aqueous phase as well as the applied transmembrane potential, likely due to ample changes in the solvation activation enthalpies. There is no fundamental limitation for applying this approach to other complex, multistate membrane protein systems. Therefore, this methodology has major implications in the area of membrane protein design and dynamics, primarily by

  20. Glass Transition Temperature of Polyetherimide: Relationship between Thin Films and Nanoporous Materials

    NASA Astrophysics Data System (ADS)

    Ozisik, Rahmi; Liu, Tong; Siegel, Richard W.

    2006-03-01

    The glass transition temperature (Tg) of nanoporous polyetherimide (PEI) was investigated using differential scanning calorimetry. Nanosized pores were created by spin coating a solution of PEI and polycaprolactone-diol (PCLD) in their common solvent dichloromethane. The nanoporous structure was created by fast phase separation during spin coating and subsequent removal of PCLD with acetone. Atomic force microscopy, scanning electron microscopy and statistical methods were used to characterize the pore structure. The glass transition temperatures of both the thin PEI films and nanoporous PEI samples were lower than that of bulk PEI. The Tg of nanoporous PEI was found to depend strongly on pore volume fraction. A Monte Carlo simulation was performed to investigate the relationship between thin films and nanoporous systems. The distribution of nearest neighbor distances (h) were obtained from the Monte Carlo simulation, which was biased to create the pore size distribution obtained from experiments. Various moments of h was calculated and used to compare the findings to thin film data.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Anodization of nanoporous alumina on impurity-induced hemisphere curved surface of aluminum at room temperature

    PubMed Central

    2011-01-01

    Nanoporous alumina which was produced by a conventional direct current anodization [DCA] process at low temperatures has received much attention in various applications such as nanomaterial synthesis, sensors, and photonics. In this article, we employed a newly developed hybrid pulse anodization [HPA] method to fabricate the nanoporous alumina on a flat and curved surface of an aluminum [Al] foil at room temperature [RT]. We fabricate the nanopores to grow on a hemisphere curved surface and characterize their behavior along the normal vectors of the hemisphere curve. In a conventional DCA approach, the structures of branched nanopores were grown on a photolithography-and-etched low-curvature curved surface with large interpore distances. However, a high-curvature hemisphere curved surface can be obtained by the HPA technique. Such a curved surface by HPA is intrinsically induced by the high-resistivity impurities in the aluminum foil and leads to branching and bending of nanopore growth via the electric field mechanism rather than the interpore distance in conventional approaches. It is noted that by the HPA technique, the Joule heat during the RT process has been significantly suppressed globally on the material, and nanopores have been grown along the normal vectors of a hemisphere curve. The curvature is much larger than that in other literatures due to different fabrication methods. In theory, the number of nanopores on the hemisphere surface is two times of the conventional flat plane, which is potentially useful for photocatalyst or other applications. PACS: 81.05.Rm; 81.07.-b; 82.45.Cc. PMID:22087646

  3. Photo-response of a nanopore device with a single embedded ZnO nanoparticle.

    PubMed

    Nguyen, Linh-Nam; Lin, Ming-Chou; Chen, Horng-Shyang; Lan, Yann-Wen; Wu, Cen-Shawn; Chang-Liao, Kuei-Shu; Chen, Chii-Dong

    2012-04-01

    The photo-response of a ZnO nanoparticle embedded in a nanopore made on a silicon nitride membrane is investigated. The ZnO nanoparticle is manipulated onto the nanopore and sandwiched between aluminum contact electrodes from both the top and bottom. The asymmetric device structure facilitates current-voltage rectification that enables photovoltaic capacity. Under illumination, the device shows open-circuit voltage as well as short-circuit current. The fill factor is found to increase at low temperatures and reaches 48.6% at 100 K. The nanopore structure and the manipulation technique provide a solid platform for exploring the electrical properties of single nanoparticles. PMID:22470086

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

    ERIC Educational Resources Information Center

    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…

  5. Toxicological responses in SW mice exposed to inhaled pyrolysates of polymer/tobacco mixtures and blended tobacco.

    PubMed

    Werley, Michael S; Lee, K Monika; Lemus-Olalde, Ranulfo

    2009-12-01

    . There was a marked sensory irritation response that recovered slowly for some polymers. Sustained body weight depression, lesions of the respiratory epithelium of the nose, and morphological changes in pulmonary alveolar macrophages (PAM) were observed after exposure to some polymer/tobacco pyrolysates. These responses were increased compared to exposure to tobacco pyrolysate alone. No moribundity or mortality occurred during the study. The data suggest that polymeric inclusions pose a minimal additional toxicologic hazard in humans. PMID:19922405

  6. Design, chirality, and flexibility in nanoporous molecule-based materials.

    PubMed

    Bradshaw, D; Claridge, J B; Cussen, E J; Prior, T J; Rosseinsky, M J

    2005-04-01

    Scientific and technological interest in porous materials with molecule-sized channels and cavities has led to an intense search for controlled chemical routes to systems with specific properties. This Account details our work on directing the assembly of open-framework structures based on molecules and investigating how the response of nanoporous examples of such materials to guests differs from classical rigid porous systems. The stabilization of chiral nanoporosity by a hierarchy of interactions that both direct and maintain a helical open-framework structure exemplifies the approach. PMID:15835874

  7. Electrochemistry of Graphene Edge Embedded Nanopores

    NASA Astrophysics Data System (ADS)

    Banerjee, Shouvik; Shim, Jiwook; Rivera, Jose; Jin, Xiaozhong; Estrada, David; Solovyeva, Vita; You, Xiuque; Pak, James; Pop, Eric; Aluru, Narayana; Bashir, Rashid

    2013-03-01

    We demonstrate a stacked graphene- Al2O3 dielectric nanopore architecture to investigate electrochemical activity at graphene edges. It has proven to be difficult to isolate electrochemical activity at the graphene edges from those at the basal planes. We use 24 nm of Al2O3 to isolate the graphene basal planes from an ionic fluid environment. Nanopores ranging from 5 to 20 nm are formed by an electron beam sculpting process to expose graphene edges. Electrochemical measurements at isolated graphene edges show current densities as high as 1.2 x 104 A/cm2, 300x greater than those reported for carbon nanotubes. Additionally, we modulate nanopore conductance by tuning the graphene edge electrochemical current as a function of the applied bias on the embedded graphene electrode. Our results indicate that electrochemical devices based on graphene nanopores have promising applications as sensitive chemical and biological sensors, energy storage devices, and DNA sequencing.

  8. Temporal resolution of nanopore sensor recordings.

    PubMed

    Rosenstein, Jacob K; Shepard, Kenneth L

    2013-01-01

    Here we discuss the limits to temporal resolution in nanopore sensor recordings, which arise from considerations of both small-signal frequency response and accumulated noise power. Nanopore sensors have strong similarities to patch-clamp ion channel recordings, except that the magnitudes of many physical parameters are substantially different. We will present examples from our recent work developing high-speed nanopore sensing platforms, in which we physically integrated nanopores with custom low-noise complementary metal-oxide-semiconductor (CMOS) circuitry. Close physical proximity of the sensor and amplifier electronics can reduce parasitic capacitances, improving both the signal-to-noise ratio and the effective temporal resolution of the recordings. PMID:24110636

  9. Nanopore sensors for nucleic acid analysis

    NASA Astrophysics Data System (ADS)

    Venkatesan, Bala Murali; Bashir, Rashid

    2011-10-01

    Nanopore analysis is an emerging technique that involves using a voltage to drive molecules through a nanoscale pore in a membrane between two electrolytes, and monitoring how the ionic current through the nanopore changes as single molecules pass through it. This approach allows charged polymers (including single-stranded DNA, double-stranded DNA and RNA) to be analysed with subnanometre resolution and without the need for labels or amplification. Recent advances suggest that nanopore-based sensors could be competitive with other third-generation DNA sequencing technologies, and may be able to rapidly and reliably sequence the human genome for under $1,000. In this article we review the use of nanopore technology in DNA sequencing, genetics and medical diagnostics.

  10. DNA nanopore translocation in glutamate solutions

    NASA Astrophysics Data System (ADS)

    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.

  11. Effect of nano-silica spheres template on CO2 capture of exchange resin-based nanoporous carbons.

    PubMed

    Meng, Long-Yue; Park, Soo-Jin

    2013-01-01

    In this work, a nanoporous carbon-based adsorbent with a higher specific surface area was directly prepared from polystyrene-based cation exchange resin (PCER) by carbonization of a mixture of nano-silica spheres. The silica/PCER composites were carbonized at 1173 K with different silica/PCER ratios. The effects of nano-silica spheres content on the pore structures of nanoporous carbons were investigated by N2 full isotherms. The CO2 capture capacity was measured by CO2 isothermal adsorption at 298 K and 1 bar. From the results, it was found that the nano-silica spheres/PCER ratio had a major influence on the CO2 capture capacity and the textural properties of the prepared nanoporous carbons. The specific surface area and total pore volume, as well as the pore size of the nanoporous carbons increased with increasing silica/PCER ratio. PMID:23646745

  12. Adiabatic burst evaporation from bicontinuous nanoporous membranes

    PubMed Central

    Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk

    2015-01-01

    Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406

  13. Theoretical models for electrochemical impedance spectroscopy and local ζ-potential of unfolded proteins in nanopores

    PubMed Central

    Vitarelli, Michael J.; Talaga, David S.

    2013-01-01

    Single solid-state nanopores find increasing use for electrical detection and/or manipulation of macromolecules. These applications exploit the changes in signals due to the geometry and electrical properties of the molecular species found within the nanopore. The sensitivity and resolution of such measurements are also influenced by the geometric and electrical properties of the nanopore. This paper continues the development of an analytical theory to predict the electrochemical impedance spectra of nanopores by including the influence of the presence of an unfolded protein using the variable topology finite Warburg impedance model previously published by the authors. The local excluded volume of, and charges present on, the segment of protein sampled by the nanopore are shown to influence the shape and peak frequency of the electrochemical impedance spectrum. An analytical theory is used to relate the capacitive response of the electrical double layer at the surface of the protein to both the charge density at the protein surface and the more commonly measured zeta potential. Illustrative examples show how the theory predicts that the varying sequential regions of surface charge density and excluded volume dictated by the protein primary structure may allow for an impedance-based approach to identifying unfolded proteins. PMID:24050368

  14. Comparative induction of somatic eye-color mutations and sex-linked recessive lethals in Drosophila melanogaster by tryptophan pyrolysates.

    PubMed

    Fujikawa, K; Inagaki, E; Uchibori, M; Kondo, S

    1983-12-01

    The mutagenicities of the products of pyrolysis of tryptophan, Trp-P-1 and Trp-P-2, on Drosophila melanogaster were examined by measuring the effects of these compounds in inducing recessive lethals and somatic eye-color mutations. Since negative results have already been obtained by the standard procedure in males, Trp-P-1 and Trp-P-2 (0.75 to 6 mg/ml) in sucrose solution were given to females for assay of recessive lethal mutations in X-chromosomes. These compounds caused a marginal increase above the control level in the mutation frequency. For the assay of effects on somatic eye-color mutations, Trp-P-1 (200 and 400 ppm) and Trp-P-2 (400 and 800 ppm) were fed to male larvae of a tester strain carrying a genetically unstable marker set of z and w+ on the X-chromosome. These compounds caused dose-dependent increases above the control level in somatic eye-color mutations in adults. It is concluded that, under the conditions used, the somatic eye-color mutation system was more sensitive than the recessive lethal system to the mutagenic effects of tryptophan pyrolysates. PMID:6419091

  15. [Pyrolysates of novel latent fragrant compound 3,6-dimethyl-2,5-pyrazinedicarboxylic acid menthol ester].

    PubMed

    Lai, Miao; Zhao, Boya; Bao, Xiaorong; Zhao, Mingqin; Ji, Xiaoming; Fu, Peipei; Zhang, Yujie

    2015-01-01

    In order to develop a new tobacco flavor released at high-temperature, the novel latent fragrant compound 3,6-dimethyl-2,5-pyrazinedicarboxylic acid menthol ester (DPAME) was synthesized by esterification using 2,3,5,6-tetramethylpyrazine and menthol as raw materials. In air atmosphere, the pyrolysis behavior of DPAME was investigated using an on-line pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) method at three temperature levels of 300, 600 and 900 degrees C, separately. The pyrolysis products were directly introduced into GC-MS and were qualitatively and semi-quantitatively analyzed. The results showed that a variety of aroma compounds of aldehydes, 3-p-menthene and menthol were released and identified at 300 degrees C. While at 600 degrees C and 900 degrees C, flavor alkene class, the alkyl pyrazines, menthol and 3-p-menthene were generated. And the types and relative amounts of pyrazines were significantly increased, at these two temperatures. Combined the analytical results of DPAME pyrolysates and the results of sensory evaluation of the cigarette, the possible pyrolysis mechanism was preliminarily speculated. The Py-GC-MS technique for the study of the pyrolysis products of DPAME was convenient and rapid. The investigation provided a reliable theoretical foundation for the perfume reinforcement technology in tobacco products, contributing to the development of cigarette products with better aroma and taste. This method is an accurate and quick way to study the pyrolysis products of latent fragrant substance. PMID:25958667

  16. Intermediate pyrolysis of agro-industrial biomasses in bench-scale pyrolyser: Product yields and its characterization.

    PubMed

    Tinwala, Farha; Mohanty, Pravakar; Parmar, Snehal; Patel, Anant; Pant, Kamal K

    2015-01-01

    Pyrolysis of woody biomass, agro-residues and seed was carried out at 500 ± 10 °C in a fixed bed pyrolyser. Bio-oil yield was found varying from 20.5% to 47.5%, whereas the biochar and pyrolysis gas ranged from 27.5% to 40% and 24.5% to 40.5%, respectively. Pyrolysis gas was measured for flame temperature along with CO, CO2, H2, CH4 and other gases composition. HHV of biochar (29.4 MJ/kg) and pyrolitic gas (8.6 MJ/kg) of woody biomass was higher analogous to sub-bituminous coal and steam gasification based producer gas respectively, whereas HHV of bio-oil obtained from seed (25.6 MJ/kg) was significantly more than husks, shells and straws. TGA-DTG studies showed the husks as potential source for the pyrolysis. Bio-oils as a major by-product of intermediate pyrolysis have several applications like substitute of furnace oil, extraction of fine chemicals, whereas biochar as a soil amendment for enhancing soil fertility and gases for thermal application. PMID:25770670

  17. Evolution of the atomic order and valence state of rare-earth atoms and uranium in a new carbon-metal composite—diphthalocyanine pyrolysate C64H32N16 Me ( Me = Y, La, Ce, Eu, and U)

    NASA Astrophysics Data System (ADS)

    Sovestnov, A. E.; Kapustin, V. K.; Tikhonov, V. I.; Fomin, E. V.; Chernenkov, Yu. P.

    2014-08-01

    The structure of a metal-carbon composite formed by the pyrolysis of diphthalocyanine of some rare-earth elements (Y, La, Ce, Eu) and uranium in the temperature range T ann = 800-1700°C has been investigated for the first time by the methods of X-ray diffraction analysis and X-ray line shift. It has been shown that, in the general case, the studied pyrolysates consist of three phases. One phase corresponds to the structure of graphite. The second phase corresponds to nitrides, carbides, and oxides of basic metal elements with a crystallite size ranging from 5 to 100 nm. The third phase is amorphous or consisting of crystallites with a size of ˜1 nm. It has been found that all the basic elements (Y, La, Ce, Eu, U) and incorporated iodine atoms in the third phase are in a chemically bound state. The previously unobserved electronic configurations have been revealed for europium. The possibility of including not only atoms of elements forming diphthalocyanine but also other elements (for example, iodine) in the composite structure is of interest, in particular, for the creation of a thermally, chemically, and radiation resistant metal-carbon matrix for the radioactive waste storage.

  18. Enzyme Reactions in Nanoporous, Picoliter Volume Containers

    PubMed Central

    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. Tailoring nanoporous materials by atomic layer deposition.

    PubMed

    Detavernier, Christophe; Dendooven, Jolien; Sree, Sreeprasanth Pulinthanathu; Ludwig, Karl F; Martens, Johan A

    2011-11-01

    Atomic layer deposition (ALD) is a cyclic process which relies on sequential self-terminating reactions between gas phase precursor molecules and a solid surface. The self-limiting nature of the chemical reactions ensures precise film thickness control and excellent step coverage, even on 3D structures with large aspect ratios. At present, ALD is mainly used in the microelectronics industry, e.g. for growing gate oxides. The excellent conformality that can be achieved with ALD also renders it a promising candidate for coating porous structures, e.g. for functionalization of large surface area substrates for catalysis, fuel cells, batteries, supercapacitors, filtration devices, sensors, membranes etc. This tutorial review focuses on the application of ALD for catalyst design. Examples are discussed where ALD of TiO(2) is used for tailoring the interior surface of nanoporous films with pore sizes of 4-6 nm, resulting in photocatalytic activity. In still narrower pores, the ability to deposit chemical elements can be exploited to generate catalytic sites. In zeolites, ALD of aluminium species enables the generation of acid catalytic activity. PMID:21695333

  20. Fracture and fatigue of ultrathin nanoporous polymer films

    NASA Astrophysics Data System (ADS)

    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

  1. Ion selectivity of graphene nanopores.

    PubMed

    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 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. PMID:27102837

  2. Ion selectivity of graphene nanopores

    NASA Astrophysics Data System (ADS)

    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.

  3. Ion selectivity of graphene nanopores

    PubMed Central

    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 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. PMID:27102837

  4. Ion selectivity of graphene nanopores

    DOE PAGESBeta

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

    2016-04-22

    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.more » Furthermore, 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.« less

  5. Built-in Quantum Dots in Nano-Porous Crystal 12CaO\\cdot7Al2O3: Simplified Views for Electronic Structure and Carrier Transport

    NASA Astrophysics Data System (ADS)

    Kamiya, Toshio; Hosono, Hideo

    2005-01-01

    12CaO\\cdot7Al2O3 (C12A7) has a unique crystal structure composed of subnanometer-sized cages and free oxygen ions in the cages. C12A7 exhibits a variety of active functions if the free oxygen ions are substituted with other active anions. Electronic conduction was attained by introducing high-density F+-like centers, which was the first demonstration of electronic conduction in oxides composed only of light elements. Chemical active species such as O- and H- are produced in C12A7 at high densities. In this paper, we first review the structure and properties of C12A7-drived materials and related \\textit{ab-initio} works, and then provide simplified views for the stability of the crystal lattice and the clathrated anions, electronic structure, and carrier transport mechanism using simple models based on crystal chemistry, classical molecular dynamics simulation and effective-mass approximation.

  6. Direct prototyping of patterned nanoporous carbon: a route from materials to on-chip devices.

    PubMed

    Shen, Caiwei; Wang, Xiaohong; Zhang, Wenfeng; Kang, Feiyu

    2013-01-01

    Prototyping of nanoporous carbon membranes with three-dimensional microscale patterns is significant for integration of such multifunctional materials into various miniaturized systems. Incorporating nano material synthesis into microelectronics technology, we present a novel approach to direct prototyping of carbon membranes with highly nanoporous structures inside. Membranes with significant thicknesses (1 ~ 40 μm) are rapidly prototyped at wafer level by combining nano templating method with readily available microfabrication techniques, which include photolithography, high-temperature annealing and etching. In particular, the high-surface-area membranes are specified as three-dimensional electrodes for micro supercapacitors and show high performance compared to reported ones. Improvements in scalability, compatibility and cost make the general strategy promising for batch fabrication of operational on-chip devices or full integration of three-dimensional nanoporous membranes with existing micro systems. PMID:23887486

  7. Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species.

    PubMed

    Tero, Ryugo; Yamashita, Ryuma; Hashizume, Hiroshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Hori, Masaru; Ito, Masafumi

    2016-09-01

    We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies. PMID:27216034

  8. Highly Efficient Elimination of Carbon Monoxide with Binary Copper-Manganese Oxide Contained Ordered Nanoporous Silicas

    NASA Astrophysics Data System (ADS)

    Lee, Jiho; Kim, Hwayoun; Lee, Hyesun; Jang, Seojun; Chang, Jeong Ho

    2016-01-01

    Ordered nanoporous silicas containing various binary copper-manganese oxides were prepared as catalytic systems for effective carbon monoxide elimination. The carbon monoxide elimination efficiency was demonstrated as a function of the [Mn]/[Cu] ratio and reaction time. The prepared catalysts were characterized by Brunauer-Emmett-Teller (BET) method, small- and wide-angle X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM) for structural analysis. Moreover, quantitative analysis of the binary metal oxides within the nanoporous silica was achieved by inductively coupled plasma (ICP). The binary metal oxide-loaded nanoporous silica showed high room temperature catalytic efficiency with over 98 % elimination of carbon monoxide at higher concentration ratio of [Mn]/[Cu].

  9. Highly Efficient Elimination of Carbon Monoxide with Binary Copper-Manganese Oxide Contained Ordered Nanoporous Silicas.

    PubMed

    Lee, Jiho; Kim, Hwayoun; Lee, Hyesun; Jang, Seojun; Chang, Jeong Ho

    2016-12-01

    Ordered nanoporous silicas containing various binary copper-manganese oxides were prepared as catalytic systems for effective carbon monoxide elimination. The carbon monoxide elimination efficiency was demonstrated as a function of the [Mn]/[Cu] ratio and reaction time. The prepared catalysts were characterized by Brunauer-Emmett-Teller (BET) method, small- and wide-angle X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM) for structural analysis. Moreover, quantitative analysis of the binary metal oxides within the nanoporous silica was achieved by inductively coupled plasma (ICP). The binary metal oxide-loaded nanoporous silica showed high room temperature catalytic efficiency with over 98 % elimination of carbon monoxide at higher concentration ratio of [Mn]/[Cu]. PMID:26744146

  10. Tunable Fabry-Pérot interferometer based on nanoporous anodic alumina for optical biosensing purposes

    PubMed Central

    2012-01-01

    Here, we present a systematic study about the effect of the pore length and its diameter on the specular reflection in nanoporous anodic alumina. As we demonstrate, the specular reflection can be controlled at will by structural tuning (i.e., by designing the pore geometry). This makes it possible to produce a wide range of Fabry-Pérot interferometers based on nanoporous anodic alumina, which are envisaged for developing smart and accurate optical sensors in such research fields as biotechnology and medicine. Additionally, to systematize the responsiveness to external changes in optical sensors based on nanoporous anodic alumina, we put forward a barcode system based on the oscillations in the specular reflection. PMID:22759928

  11. Nanoporous TiO2 developed from two templates for their use in photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Mumtaz, Asad; Mohamed, Norani Muti

    2015-07-01

    Described work is a development of templated nanoporous TiO2 using two different substrates. Controlled parametric syntheses of nanoporous textures give rise high surface area as well as high aspect ratios. High electric field application for specific time and the composition of electrolytes used in synthesis cell needs a careful study. Ethylene glycol, an organic solvent, with F- free ions in the presence of HCl is used for the purpose in cell bath. Ti templated and Ti-Al templated nanoporous TiO2 shows lower porosity at low voltage treatments, while both the templates reveal high porous structure at 20V. Increasing the time of Ti template for a specific voltage leads to collapse of pores while it enhances the roughness of the walls of collapsed pores and hence improving the surface rea. Energy dispersive x-ray (EDX) elemental analysis confirms the presence of TiO2.

  12. Direct Prototyping of Patterned Nanoporous Carbon: A Route from Materials to On-chip Devices

    PubMed Central

    Shen, Caiwei; Wang, Xiaohong; Zhang, Wenfeng; Kang, Feiyu

    2013-01-01

    Prototyping of nanoporous carbon membranes with three-dimensional microscale patterns is significant for integration of such multifunctional materials into various miniaturized systems. Incorporating nano material synthesis into microelectronics technology, we present a novel approach to direct prototyping of carbon membranes with highly nanoporous structures inside. Membranes with significant thicknesses (1 ~ 40 μm) are rapidly prototyped at wafer level by combining nano templating method with readily available microfabrication techniques, which include photolithography, high-temperature annealing and etching. In particular, the high-surface-area membranes are specified as three-dimensional electrodes for micro supercapacitors and show high performance compared to reported ones. Improvements in scalability, compatibility and cost make the general strategy promising for batch fabrication of operational on-chip devices or full integration of three-dimensional nanoporous membranes with existing micro systems. PMID:23887486

  13. Engineering a Transmembrane Nanopore Ion Channel from a Membrane Breaker Peptide.

    PubMed

    Lella, Muralikrishna; Mahalakshmi, Radhakrishnan

    2016-07-01

    Re-engineering nature's molecules is an ideal strategy to obtain explicit functionality such as synthetic molecular machines, yet novel strategies for producing engineered molecular channels are few. Here we report a peptide engineering strategy through sequence reversal, which we applied on the first transmembrane peptide of the mycobacteriophage membranoporin protein holin. We have successfully redesigned the membrane rupture property of this peptide to form specific nanopore ion channels. We report the structural characterization and electrophysiology measurements of a library of 28-residue engineered membrane peptides, with remarkable ion channel behavior. We further identify that key residues at the peptide terminus, the central proline, charge distribution, and hydropathy index of the peptide together contribute to the channel properties that we measure. Our sequence reversal strategy for peptide engineering to successfully obtain nanopore channels can pave the way for better biobased design of controlled nanopores, using only natural amino acids. PMID:27257735

  14. InGaN Light-Emitting Diodes with an Embedded Nanoporous GaN Distributed Bragg Reflectors.

    PubMed

    Shiu, Guo-Yi; Chen, Kuei-Ting; Fan, Feng-Hsu; Huang, Kun-Pin; Hsu, Wei-Ju; Dai, Jing-Jie; Lai, Chun-Feng; Lin, Chia-Feng

    2016-01-01

    InGaN light emitting diodes (LED) structure with an embedded 1/4λ-stack nanoporous-GaN/undoped-GaN distributed Bragg reflectors (DBR) structure have been demonstrated. Si-heavily doped GaN epitaxial layers (n(+)-GaN) in the 12-period n(+)-GaN/u-GaN stack structure are transformed into low refractive index nanoporous GaN structure through the doping-selective electrochemical wet etching process. The central wavelength of the nanoporous DBR structure was located at 442.3 nm with a 57 nm linewidth and a 97.1% peak reflectivity. The effective cavity length (6.0λ), the effective penetration depth (278 nm) in the nanoporous DBR structure, and InGaN active layer matching to Fabry-Pérot mode order 12 were observed in the far-field photoluminescence radiative spectra. High electroluminescence emission intensity and line-width narrowing effect were measured in the DBR-LED compared with the non-treated LED structure. Non-linear emission intensity and line-width reducing effect, from 11.8 nm to 0.73 nm, were observed by increasing the laser excited power. Resonant cavity effect was observed in the InGaN LED with bottom nanoporous-DBR and top GaN/air interface. PMID:27363290

  15. InGaN Light-Emitting Diodes with an Embedded Nanoporous GaN Distributed Bragg Reflectors

    NASA Astrophysics Data System (ADS)

    Shiu, Guo-Yi; Chen, Kuei-Ting; Fan, Feng-Hsu; Huang, Kun-Pin; Hsu, Wei-Ju; Dai, Jing-Jie; Lai, Chun-Feng; Lin, Chia-Feng

    2016-07-01

    InGaN light emitting diodes (LED) structure with an embedded 1/4λ-stack nanoporous-GaN/undoped-GaN distributed Bragg reflectors (DBR) structure have been demonstrated. Si-heavily doped GaN epitaxial layers (n+-GaN) in the 12-period n+-GaN/u-GaN stack structure are transformed into low refractive index nanoporous GaN structure through the doping-selective electrochemical wet etching process. The central wavelength of the nanoporous DBR structure was located at 442.3 nm with a 57 nm linewidth and a 97.1% peak reflectivity. The effective cavity length (6.0λ), the effective penetration depth (278 nm) in the nanoporous DBR structure, and InGaN active layer matching to Fabry-Pérot mode order 12 were observed in the far-field photoluminescence radiative spectra. High electroluminescence emission intensity and line-width narrowing effect were measured in the DBR-LED compared with the non-treated LED structure. Non-linear emission intensity and line-width reducing effect, from 11.8 nm to 0.73 nm, were observed by increasing the laser excited power. Resonant cavity effect was observed in the InGaN LED with bottom nanoporous-DBR and top GaN/air interface.

  16. InGaN Light-Emitting Diodes with an Embedded Nanoporous GaN Distributed Bragg Reflectors

    PubMed Central

    Shiu, Guo-Yi; Chen, Kuei-Ting; Fan, Feng-Hsu; Huang, Kun-Pin; Hsu, Wei-Ju; Dai, Jing-Jie; Lai, Chun-Feng; Lin, Chia-Feng

    2016-01-01

    InGaN light emitting diodes (LED) structure with an embedded 1/4λ-stack nanoporous-GaN/undoped-GaN distributed Bragg reflectors (DBR) structure have been demonstrated. Si-heavily doped GaN epitaxial layers (n+-GaN) in the 12-period n+-GaN/u-GaN stack structure are transformed into low refractive index nanoporous GaN structure through the doping-selective electrochemical wet etching process. The central wavelength of the nanoporous DBR structure was located at 442.3 nm with a 57 nm linewidth and a 97.1% peak reflectivity. The effective cavity length (6.0λ), the effective penetration depth (278 nm) in the nanoporous DBR structure, and InGaN active layer matching to Fabry-Pérot mode order 12 were observed in the far-field photoluminescence radiative spectra. High electroluminescence emission intensity and line-width narrowing effect were measured in the DBR-LED compared with the non-treated LED structure. Non-linear emission intensity and line-width reducing effect, from 11.8 nm to 0.73 nm, were observed by increasing the laser excited power. Resonant cavity effect was observed in the InGaN LED with bottom nanoporous-DBR and top GaN/air interface. PMID:27363290

  17. The influence of nanopore dimensions on the electrochemical properties of nanopore arrays studied by impedance spectroscopy.

    PubMed

    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

  18. Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

    PubMed Central

    2012-01-01

    The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing. PMID:23272786

  19. Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid.

    PubMed

    Nourmohammadi, Abolghasem; Asadabadi, Saeid Jalali; Yousefi, Mohammad Hasan; Ghasemzadeh, Majid

    2012-01-01

    The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing. PMID:23272786

  20. Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

    NASA Astrophysics Data System (ADS)

    Nourmohammadi, Abolghasem; Asadabadi, Saeid Jalali; Yousefi, Mohammad Hasan; Ghasemzadeh, Majid

    2012-12-01

    The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing.

  1. Neurite development in PC12 cells cultured on nanopillars and nanopores with sizes comparable with filopodia

    PubMed Central

    Haq, Furqan; Anandan, Venkatramani; Keith, Charles; Zhang, Guigen

    2007-01-01

    We investigated the effect of nanoscale topography on neurite development in pheochromocytoma (PC12 cells) by culturing the cells on substrates having nanoscale pillars and pores with sizes comparable with filipodia. We found that cells on nanopillars and nanopores developed fewer and shorter neurites than cells on smooth substrates, and that cells on nanopores developed more and longer neurites than cells on nanopillars. These results suggest that PC12 cells were spatially aware of the difference in the nanoscale structures of the underlying substrates and responded differently in their neurite extension. This finding points to the possibility of using nanoscale topographic features to control neurite development in neurons. PMID:17722518

  2. Electric field-controlled water permeation coupled to ion transport through a nanopore

    NASA Astrophysics Data System (ADS)

    Dzubiella, J.; Allen, R. J.; Hansen, J.-P.

    2004-03-01

    We report molecular dynamics simulations of a generic hydrophobic nanopore connecting two reservoirs which are initially at different Na+ concentrations, as in a biological cell. The nanopore is impermeable to water under equilibrium conditions, but the strong electric field caused by the ionic concentration gradient drives water molecules in. The density and structure of water in the pore are highly field dependent. In a typical simulation run, we observe a succession of cation passages through the pore, characterized by approximately bulk mobility. These ion passages reduce the electric field, until the pore empties of water and closes to further ion transport, thus providing a possible mechanism for biological ion channel gating.

  3. Anti-reflective nanoporous silicon for efficient hydrogen production

    DOEpatents

    Oh, Jihun; Branz, Howard M

    2014-05-20

    Exemplary embodiments are disclosed of anti-reflective nanoporous silicon for efficient hydrogen production by photoelectrolysis of water. A nanoporous black Si is disclosed as an efficient photocathode for H.sub.2 production from water splitting half-reaction.

  4. Fabrication of a three-dimensional nanoporous polymer film as a diffuser for microcavity OLEDs

    NASA Astrophysics Data System (ADS)

    Pyo, Beom; Cho, Ye Ram; Suh, Min Chul

    2015-09-01

    We used a nanoporous polymer film prepared by cellulose acetate butyrate with ~40% of optical haze value as a diffuser. It was fabricated by a simple spin-coating process during continuous water mist supply by a humidifier. The pores were created by the elastic bouncing mechanism (rather than the thermocapillary convection mechanism) of the supplied water droplets. The shapes and sizes of the caves formed near the polymer surface are randomly distributed, with a relatively narrow pore size distribution (300-500 nm). Specifically, we focused on controlling the surface morphology to give a three-dimensional (3D) multi-stacked nanocave structure because we had already learnt that two-dimensional nanoporous structures showed serious loss of luminance in the forward direction. Using this approach, we found that the 3D nanoporous polymer film can effectively reduce the viewing angle dependency of strong microcavity OLEDs without any considerable decrease in the total intensity of the out-coupled light. We applied this nanoporous polymer film to microcavity OLEDs to investigate the possibility of using it as a diffuser layer. The resulting nanoporous polymer film effectively reduced the viewing angle dependency of the microcavity OLEDs, although a pixel blurring phenomenon occurred. Despite its negative effects, such as the drop in efficiency in the forward direction and the pixel blurring, the introduction of a nanoporous polymer film as a scattering medium on the back side of the glass substrate eliminated the viewing angle dependency. Thus, this approach is a promising method to overcome the serious drawbacks of microcavity OLEDs.

  5. MspA Nanopores from Subunit Dimers

    PubMed Central

    Pavlenok, Mikhail; Derrington, Ian M.; Gundlach, Jens H.; Niederweis, Michael

    2012-01-01

    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 sequencing of DNA. PMID

  6. MspA nanopores from subunit dimers.

    PubMed

    Pavlenok, Mikhail; Derrington, Ian M; Gundlach, Jens H; Niederweis, Michael

    2012-01-01

    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 sequencing of DNA. PMID

  7. Solar-light photoamperometric and photocatalytic properties of quasi-transparent TiO2 nanoporous thin films.

    PubMed

    Ji, Yajun; Lin, Keng-Chu; Zheng, Hegen; Liu, Chung-Chiun; Dudik, Laurie; Zhu, Junjie; Burda, Clemens

    2010-11-01

    Transparent photocatalytic surfaces are of ever increasing importance for many applications on self-cleaning windows and tiles in everyday applications. Here, we report the formation and photocatalytic testing of a quasi-transparent thin and nanoporous titania films deposited on glass plates. Sputtered Ti thin films were anodized in fluoride-ion-containing neutral electrolytes to form optically semitransparent nanoporous films, which transformed to be completely transparent after thermal annealing. The nanoporous films were studied at different stages, such as before and after anodization, as well as after thermal annealing using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis and Raman spectroscopy. It was observed that anodization at 20 V of high-temperature deposited titanium films resulted in regular nanopore films with pore diameters of 30 nm. Structural investigations on the transparent nanopore arrays reveal the presence of anatase phase TiO(2) even after annealing at 500 °C, which was confirmed by XRD and Raman spectroscopy measurements. The solar-light induced photocatalytic decomposition of stearic acid and photoconductivity characteristics of these nanoporous thin films are also presented. PMID:20973502

  8. Stacked Graphene-Al2O3 Nanopore Sensors for Sensitive Detection of DNA and DNA-Protein Complexes

    PubMed Central

    Venkatesan, Bala Murali; Estrada, David; Banerjee, Shouvik; Jin, Xiaozhong; Dorgan, Vincent E.; Bae, Myung-Ho; Aluru, Narayana R.; Pop, Eric; Bashir, Rashid

    2012-01-01

    We report the development of a multilayered graphene-Al2O3 nanopore platform for the sensitive detection of DNA and DNA-protein complexes. Graphene-Al2O3 nanolaminate membranes are formed by sequentially depositing layers of graphene and Al2O3 with nanopores being formed in these membranes using an electron-beam sculpting process. The resulting nanopores are highly robust, exhibit low electrical noise (significantly lower than nanopores in pure graphene), are highly sensitive to electrolyte pH at low KCl concentrations (attributed to the high buffer capacity of Al2O3) and permit the electrical biasing of the embedded graphene electrode, thereby allowing for three terminal nanopore measurements. In proof-of-principle biomolecule sensing experiments, the folded and unfolded transport of single DNA molecules and RecA coated DNA complexes could be discerned with high temporal resolution. The process described here also enables nanopore integration with new graphene based structures, including nanoribbons and nanogaps, for single molecule DNA sequencing and medical diagnostic applications. PMID:22165962

  9. Stacked graphene-Al2O3 nanopore sensors for sensitive detection of DNA and DNA-protein complexes.

    PubMed

    Venkatesan, Bala Murali; Estrada, David; Banerjee, Shouvik; Jin, Xiaozhong; Dorgan, Vincent E; Bae, Myung-Ho; Aluru, Narayana R; Pop, Eric; Bashir, Rashid

    2012-01-24

    We report the development of a multilayered graphene-Al(2)O(3) nanopore platform for the sensitive detection of DNA and DNA-protein complexes. Graphene-Al(2)O(3) nanolaminate membranes are formed by sequentially depositing layers of graphene and Al(2)O(3), with nanopores being formed in these membranes using an electron-beam sculpting process. The resulting nanopores are highly robust, exhibit low electrical noise (significantly lower than nanopores in pure graphene), are highly sensitive to electrolyte pH at low KCl concentrations (attributed to the high buffer capacity of Al(2)O(3)), and permit the electrical biasing of the embedded graphene electrode, thereby allowing for three terminal nanopore measurements. In proof-of-principle biomolecule sensing experiments, the folded and unfolded transport of single DNA molecules and RecA-coated DNA complexes could be discerned with high temporal resolution. The process described here also enables nanopore integration with new graphene-based structures, including nanoribbons and nanogaps, for single-molecule DNA sequencing and medical diagnostic applications. PMID:22165962

  10. Environmental Green Chemistry Applications of Nanoporous Carbons

    SciTech Connect

    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.

  11. Nanoporous Au: an unsupported pure gold catalyst?

    SciTech Connect

    Wittstock, A; Neumann, B; Schaefer, A; Dumbuya, K; Kuebel, C; Biener, M; Zielasek, V; Steinrueck, H; Gottfried, M; Biener, J; Hamza, A; B?umer, M

    2008-09-04

    The unique properties of gold especially in low temperature CO oxidation have been ascribed to a combination of various effects. In particular, particle sizes below a few nm and specific particle-support interactions have been shown to play important roles. On the contrary, recent reports revealed that monolithic nanoporous gold (npAu) prepared by leaching a less noble metal, such as Ag, out of the corresponding alloy can also exhibit remarkably high catalytic activity for CO oxidation, even though no support is present. Therefore, it was claimed to be a pure and unsupported gold catalyst. We investigated npAu with respect to its morphology, surface composition and catalytic properties. In particular, we studied the reaction kinetics for low temperature CO oxidation in detail taking mass transport limitation due to the porous structure of the material into account. Our results reveal that Ag, even if removed almost completely from the bulk, segregates to the surface resulting in surface concentrations of up to 10 at%. Our data suggest that this Ag plays a significant role in activation of molecular oxygen. Therefore, npAu should be considered as a bimetallic catalyst rather than a pure Au catalyst.

  12. Diffusive Silicon Nanopore Membranes for Hemodialysis Applications

    PubMed Central

    Kim, Steven; Feinberg, Benjamin; Kant, Rishi; Chui, Benjamin; Goldman, Ken; Park, Jaehyun; Moses, Willieford; Blaha, Charles; Iqbal, Zohora; Chow, Clarence; Wright, Nathan; Fissell, William H.; Zydney, Andrew; Roy, Shuvo

    2016-01-01

    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. PMID:27438878

  13. Diffusive Silicon Nanopore Membranes for Hemodialysis Applications.

    PubMed

    Kim, Steven; Feinberg, Benjamin; Kant, Rishi; Chui, Benjamin; Goldman, Ken; Park, Jaehyun; Moses, Willieford; Blaha, Charles; Iqbal, Zohora; Chow, Clarence; Wright, Nathan; Fissell, William H; Zydney, Andrew; Roy, Shuvo

    2016-01-01

    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. PMID:27438878

  14. Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

    NASA Astrophysics Data System (ADS)

    Gobal, Fereydoon; Faraji, Masoud

    2014-12-01

    Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc-cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 1 M NaOH solution. The electrochemical data demonstrated that the electrodes display good capacitive behavior with a specific capacitance of 430 F g-1 at a current density of 1.0 A g-1 and specific capacitance retention of ca. 80 % after 10 days of being used in electrochemical experiments, indicating to be promising electroactive materials for supercapacitors. Furthermore, in comparison with electrodes prepared by simple cathodic deposition of cobalt onto TiO2 nanotubes(without dealloying procedure), the impedance studies showed improved performances likely due to nanoporous/cracked structures of electrodes fabricated by dealloying of zinc, which provide fast ion and electron transfer routes and large reaction surface area with the ensued fast reaction kinetics.

  15. Bonding Low-density Nanoporous Metal Foams Using Sputtered Solder

    SciTech Connect

    Bono, M; Cervantes, O; Akaba, C; Hamza, A; Foreman, R; Teslich, N

    2007-08-21

    A method has been developed for bonding low-density nanoporous metal foam components to a substrate using solder that is sputtered onto the surfaces. Metal foams have unusual properties that make them excellent choices for many applications, and as technologies for processing these materials are evolving, their use in industry is increasing dramatically. Metal foams are lightweight and have advantageous dynamic properties, which make them excellent choices for many structural applications. They also provide good acoustic damping, low thermal conductivity, and excellent energy absorption characteristics. Therefore, these materials are commonly used in the automotive, aerospace, construction, and biomedical industries. The synthesis of nanoporous metal foams with a cell size of less then 1 {micro}m is an emerging technology that is expected to lead to widespread application of metal foams in microdevices, such as sensors and actuators. One of the challenges to manufacturing components from metal foams is that they can be difficult to attach to other structures without degrading their properties. For example, traditional liquid adhesives cannot be used because they are absorbed into foams. The problem of bonding or joining can be particularly difficult for small-scale devices made from nanoporous foam, due to the requirement for a thin bond layer. The current study addresses this problem and develops a method of soldering a nanoporous metal foam to a substrate with a bond thickness of less than 2 {micro}m. There are many applications that require micro-scale metal foams precisely bonded to substrates. This study was motivated by a physics experiment that used a laser to drive a shock wave through an aluminum foil and into a copper foam, in order to determine the speed of the shock in the copper foam. To avoid disturbing the shock, the interface between the copper foam and the aluminum substrate had to be as thin as possible. There are many other applications that

  16. Synthesis and electrochemical characterization of anode material with titanium-silicon alloy solid core/nanoporous silicon shell structures for lithium rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Park, Jung-Bae; Ham, Jun-Sik; Shin, Min-Seon; Park, Hong-Kyu; Lee, Yong-Ju; Lee, Sung-Man

    2015-12-01

    Composite materials composed of titanium-silicon alloy (Ti-Si alloy) core and porous Si shell (core-shell (C/S) composite) are prepared, and their electrochemical performance as anode materials for lithium-ion batteries is reported. The C/S composites are fabricated by selective etching of the titanium silicide phase in the surface region of a Ti-Si alloy that consists of titanium silicide and Si phases. The Ti-Si alloy is mechanically alloyed (MA) by ball-milling a mixture containing elemental Si and TiH2. Prior to the etching treatment, some of the MA samples are annealed at temperatures ranging from 600 to 800 °C to further develop the crystalline structure; annealing leads to the increase in the crystallite size of the Si and silicide phases. Thereby, the core and shell structure of the C/S composites and their electrochemical behaviors are controlled. Electrodes prepared by blending the C/S composites with graphite show good cycle performance and rate capability.

  17. Bench-top method for fabricating glass-sealed nanodisk electrodes, glass nanopore electrodes, and glass nanopore membranes of controlled size.

    PubMed

    Zhang, Bo; Galusha, Jeremy; Shiozawa, Peter G; Wang, Gangli; Bergren, Adam Johan; Jones, Ronald M; White, Ryan J; Ervin, Eric N; Cauley, Chris C; White, Henry S

    2007-07-01

    A simple benchtop method of fabricating glass-sealed nanometer-sized Au and Pt disk electrodes, glass nanopore electrodes, and glass nanopore membranes is reported. The synthesis of all three structures is initiated by sealing the tips of electrochemically sharpened Au and Pt microwires into glass membranes at the end of a soda lime or lead glass capillary. Pt and Au nanodisk electrodes are obtained by hand polishing using a high-input impedance metal oxide semiconductor field effect transistor (MOSFET)-based circuit to monitor the radius of the metal disk. Proper biasing of the MOSFET circuit, based on a numerical analysis of the polishing circuit impedance, allows for the reproducible fabrication of Pt disk electrodes of radii as small as 10 nm. Significantly smaller background currents in voltammetric measurements are obtained using lead glass capillaries, a consequence of the lower mobility of Pb(2+) (relative to Na(+)) in the glass matrix. Glass nanopore electrodes and glass nanopore membranes are fabricated, respectively, by removal of part or all of the metal sealed in the glass membranes. The nanostructures are characterized by atomic force microscopy, steady-state voltammetry, and ion conductivity measurements. PMID:17550232

  18. Nanoporous Structures Similar to Those Reported from Squid Sucker Teeth are also Present in Egg Shells of a Terrestrial Flatworm (Platyhelminthes; Rhabditophora; Geoplanidae) from Hachijojima (Izu Islands, Japan).

    PubMed

    Meyer-Rochow, Victor Benno; Miinalainen, Ilkka

    2016-07-01

    Shells of the egg cocoon of a terrestrial planarian (Diversibipalium sp.) from Hachijojima were found to be composed of a lattice of parallel nanotubes of ca. 120 nm diameter oriented perpendicular to the shell's surface. The arrangement of the porous proteinaceous tubes closely resembles that has recently been reported from the sucker teeth of squid and to date is the only other example of this kind of structure. Although the array of nanotubes undoubtedly contributes to the stiffness of the shell and helps protecting the embryo, questions such as to how the planary worm produces the array of nanotubes and what exactly their chemical and physical properties are versus those of the squid sucker tooth still remain to be answered. PMID:27278842

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

    NASA Astrophysics Data System (ADS)

    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

  20. Broad pore channels as molecular highways in nanoporous catalysts: Multiscale modeling, optimization and applications

    NASA Astrophysics Data System (ADS)

    Wang, Gang

    Porous catalysts are widely used in many applications, ranging from petroleum refining to fuel cells and emission control. Nanoporous catalysts like zeolites often have an extremely large internal surface area (e.g., 1000m 2/g), which is beneficial because catalytic reactions occur on the surface. However, their small pore size leads to slow molecular transport and pore blocking, limiting the efficient use of the catalytic material. This indicates that, apart from the nanopores where reactions actually occur, a "distribution" network of broad pore channels is needed for molecules to quickly move in and out of the catalyst. Despite considerable experimental efforts in the introduction of broad pore channels into nanoporous catalysts in a controllable way, the following generic question remains: which broad pore channel network should be included in a nanoporous catalyst for optimal catalyst performance? To this end, model-based optimizations were used to optimize hierarchically structured porous catalysts, containing both broad pore channels and nanopores. Extensive optimizations showed that, for a single, isothermal reaction, the nanoporous walls (i.e., the nanoporous catalytic material between two neighboring broad pore channels) should be sufficiently thin so that diffusion limitations vanish inside them. It was found that the optimal catalytic performance is dictated by the generalized distributor Thiele modulus, which is defined in a way analogous to the generalized Thiele modulus, but using the molecular diffusivity in the broad pore channels, rather than the effective diffusivity in the nanopores. The use of hierarchically structured porous catalysts was demonstrated for power plant deNOx catalysis and autothermal reforming of methane. For deNOx catalysis, overall catalytic activity in a mesoporous deNOx catalyst with a median pore size of 32.5 nm could be increased by a factor of 1.8-2.8 simply by introducing 8-22mum broad pore channels (occupying 20-40% of

  1. Synthesis of self-detached nanoporous titanium-based metal oxide

    SciTech Connect

    Hu, F.; Wen, Y.; Chan, K.C.; Yue, T.M.; Zhou, Y.Z.; Zhu, S.L.; Yang, X.J.

    2015-09-15

    In this study, self-detached nanoporous titanium-based metal oxide was synthesized for the first time by ultrafast anodization in a fluoride-free electrolyte containing 10% HNO{sub 3}. The nanoporous oxide has through-holes with diameters ranging from 10 to 60 nm. The as-formed oxides are amorphous, and were transformed to crystalline structures by annealing. The performance of a dye sensitized solar cell using nanoporpous Ti–10Zr oxide (TZ10) was further studied. It was found that the TZ10 film could increase both the short-circuit current and the open-circuit photovoltage of the solar cell. The overall efficiency of the solar cell was 6.99%, an increase of 20.7% as compared to that using a pure TiO{sub 2} (P25) film. - Graphical abstract: The nanoporous Ti–xZr(x=10, 30) oxide layers are fabricated by anodizing in a dilute nitric acid solvent. The power conversion efficiency of the DSSC by a covering of a Ti–10Zr thin film is increased by 20.7%, with an η of 7.69% , a short circuit current of 12.4 mA/cm{sup 2}, a open circuit voltage of 0.833 V, and a fill factor of 0.679. - Highlights: • Self-detached nanoporous titanium-based metal (TiZr) oxide was synthesized. • The TiZr oxides have through-hole nanopores with diameters ranging from 10 to 60 nm. • The nanoporous Ti–10Zr oxide can improve the power conversion efficiency of a DSSC.

  2. Nanopore Fabrication by Controlled Dielectric Breakdown

    PubMed Central

    Tabard-Cossa, Vincent

    2014-01-01

    Nanofabrication techniques for achieving dimensional control at the nanometer scale are generally equipment-intensive and time-consuming. The use of energetic beams of electrons or ions has placed the fabrication of nanopores in thin solid-state membranes within reach of some academic laboratories, yet these tools are not accessible to many researchers and are poorly suited for mass-production. Here we describe a fast and simple approach for fabricating a single nanopore down to 2-nm in size with sub-nm precision, directly in solution, by controlling dielectric breakdown at the nanoscale. The method relies on applying a voltage across an insulating membrane to generate a high electric field, while monitoring the induced leakage current. We show that nanopores fabricated by this method produce clear electrical signals from translocating DNA molecules. Considering the tremendous reduction in complexity and cost, we envision this fabrication strategy would not only benefit researchers from the physical and life sciences interested in gaining reliable access to solid-state nanopores, but may provide a path towards manufacturing of nanopore-based biotechnologies. PMID:24658537

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

    PubMed

    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. PMID:25765268

  4. Graphene Nanopore Support System for Simultaneous High-Resolution AFM Imaging and Conductance Measurements

    PubMed Central

    2015-01-01

    Accurately defining the nanoporous structure and sensing the ionic flow across nanoscale pores in thin films and membranes has a wide range of applications, including characterization of biological ion channels and receptors, DNA sequencing, molecule separation by nanoparticle films, sensing by block co-polymers films, and catalysis through metal–organic frameworks. Ionic conductance through nanopores is often regulated by their 3D structures, a relationship that can be accurately determined only by their simultaneous measurements. However, defining their structure–function relationships directly by any existing techniques is still not possible. Atomic force microscopy (AFM) can image the structures of these pores at high resolution in an aqueous environment, and electrophysiological techniques can measure ion flow through individual nanoscale pores. Combining these techniques is limited by the lack of nanoscale interfaces. We have designed a graphene-based single-nanopore support (∼5 nm thick with ∼20 nm pore diameter) and have integrated AFM imaging and ionic conductance recording using our newly designed double-chamber recording system to study an overlaid thin film. The functionality of this integrated system is demonstrated by electrical recording (<10 pS conductance) of suspended lipid bilayers spanning a nanopore and simultaneous AFM imaging of the bilayer. PMID:24581087

  5. Dealloying-driven nanoporous palladium with superior electrochemical actuation performance.

    PubMed

    Zhang, Jie; Bai, Qingguo; Zhang, Zhonghua

    2016-04-01

    Metal-hydrogen (in particular, Pd-H) interactions have been receiving considerable attention over the past 150 years within the scope of hydrogen storage, catalytic hydrogenation, hydrogen embrittlement and hydrogen-induced interfacial failure. Here, for the first time, we show that the coupling of hydrogen adsorption and absorption could trigger giant reversible strain in bulk nanoporous Pd (np-Pd) in a weakly adsorbed NaF electrolyte. The bulk np-Pd with a hierarchically porous structure and a ligament/channel size of ∼10 nm was fabricated using a dealloying strategy with compositional/structural design of the precursor. The np-Pd actuator exhibits a giant reversible strain of up to 3.28% (stroke of 137.8 μm), which is a 252% enhancement in comparison to the state-of-the-art value of 1.3% in np-AuPt. The strain rate (∼10(-5) s(-1)) of np-Pd is two orders of magnitude higher than that of current metallic actuators. Moreover, the volume-/mass-specific strain energy density (10.71 MJ m(-3)/3811 J kg(-1)) of np-Pd reaches the highest level compared with that of previously reported actuator materials. The outstanding actuation performance of np-Pd could be attributed to the coupling of hydrogen adsorption/absorption and its unique hierarchically nanoporous structure. Our findings provide valuable information for the design of novel high-performance metallic actuators. PMID:26975834

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

    SciTech Connect

    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.

  7. Spray pyrolysed Cu2ZnSnS4/In2S3 thin film solar cell: Effect of varying copper concentration on cell parameters

    NASA Astrophysics Data System (ADS)

    Menon, M. R. Rajesh; Rajeshmon, V. G.; Thomas, Titu; Kartha, C. Sudha; Vijayakumar, K. P.

    2016-05-01

    A double layer Cu2ZnSnS4 absorber was employed for the first time to improve the performance of spray pyrolysed Cu2ZnSnS4/In2S3 thin film solar cell. Copper concentration in the two layers of Cu2ZnSnS4 was adjusted and effect on performance parameters was studied. It was observed that higher copper concentration in the absorber layer adjacent to the electrode is beneficial for device performance, whereas, lower copper concentration in absorber layer near to the junction has detrimental effect on the device properties.

  8. Rational engineering of nanoporous anodic alumina optical bandpass filters

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  9. Thin Nanoporous Metal-Insulator-Metal Membranes.

    PubMed

    Aramesh, Morteza; Djalalian-Assl, Amir; Yajadda, Mir Massoud Aghili; Prawer, Steven; Ostrikov, Kostya Ken

    2016-02-01

    Insulating nanoporous materials are promising platforms for soft-ionizing membranes; however, improvement in fabrication processes and the quality and high breakdown resistance of the thin insulator layers are needed for high integration and performance. Here, scalable fabrication of highly porous, thin, silicon dioxide membranes with controlled thickness is demonstrated using plasma-enhanced chemical-vapor-deposition. The fabricated membranes exhibit good insulating properties with a breakdown voltage of 1 × 10(7) V/cm. Our calculations suggest that the average electric field inside a nanopore of the membranes can be as high as 1 × 10(6) V/cm; sufficient for ionization of wide range of molecules. These metal-insulator-metal nanoporous arrays are promising for applications such soft ionizing membranes for mass spectroscopy. PMID:26846250

  10. Dynamic crack propagation through nanoporous media

    NASA Astrophysics Data System (ADS)

    Nguyen, Thao; Wilkerson, Justin

    2015-06-01

    The deformation and failure of nanoporous metals may be considerably different than that of more traditional bulk porous metals. The length scales in traditional bulk porous metals are typically large enough for classic plasticity and buckling to be operative. However, the extremely small length scales associated with nanoporous metals may inhibit classic plasticity mechanisms. Here, we motivate an alternative nanovoid growth mechanism mediated by dislocation emission. Following an approach similar to Lubarda and co-workers, we make use of stability arguments applied to the analytic solutions of the elastic interactions of dislocations and voids to derive a simple stress-based criterion for emission activation. We then propose a dynamic nanovoid growth law that is motivated by the kinetics of dislocation emission. The resulting failure model is implemented into a commercial finite element software to simulate dynamic crack growth. The simulations reveal that crack propagation through a nanoporous media proceeds at somewhat faster velocities than through the more traditional bulk porous metal.

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

    SciTech Connect

    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 improved structural and

  12. Water desalination across nanoporous graphene.

    PubMed

    Cohen-Tanugi, David; Grossman, Jeffrey C

    2012-07-11

    We show that nanometer-scale pores in single-layer freestanding graphene can effectively filter NaCl salt from water. Using classical molecular dynamics, we report the desalination performance of such membranes as a function of pore size, chemical functionalization, and applied pressure. Our results indicate that the membrane's ability to prevent the salt passage depends critically on pore diameter with adequately sized pores allowing for water flow while blocking ions. Further, an investigation into the role of chemical functional groups bonded to the edges of graphene pores suggests that commonly occurring hydroxyl groups can roughly double the water flux thanks to their hydrophilic character. The increase in water flux comes at the expense of less consistent salt rejection performance, which we attribute to the ability of hydroxyl functional groups to substitute for water molecules in the hydration shell of the ions. Overall, our results indicate that the water permeability of this material is several orders of magnitude higher than conventional reverse osmosis membranes, and that nanoporous graphene may have a valuable role to play for water purification. PMID:22668008

  13. Nanoporous polymers for hydrogen storage.

    PubMed

    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. PMID:19360719

  14. Fracture of nanoporous organosilicate thin films

    NASA Astrophysics Data System (ADS)

    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

  15. A FIB induced boiling mechanism for rapid nanopore formation.

    PubMed

    Das, K; Freund, J B; Johnson, H T

    2014-01-24

    Focused ion beam (FIB) technology is widely used to fabricate nanopores in solid-state membranes. These nanopores have desirable thermomechanical properties for applications such as high-throughput DNA sequencing. Using large scale molecular dynamics simulations of the FIB nanopore formation process, we show that there is a threshold ion delivery rate above which the mechanism underlying nanopore formation changes. At low rates nanopore formation is slow, with the rate proportional to the ion flux and therefore limited by the sputter rate of the target material. However, at higher fluxes nanopores form via a thermally dominated process, consistent with an explosive boiling mechanism. In this case, mass is rapidly rearranged via bubble growth and coalescence, much more quickly than would occur during sputtering. This mechanism has the potential to greatly speed up nanopore formation. PMID:24356374

  16. DNA Translocations through Solid-State Plasmonic Nanopores

    PubMed Central

    2015-01-01

    Nanopores enable label-free detection and analysis of single biomolecules. Here, we investigate DNA translocations through a novel type of plasmonic nanopore based on a gold bowtie nanoantenna with a solid-state nanopore at the plasmonic hot spot. Plasmonic excitation of the nanopore is found to influence both the sensor signal (nanopore ionic conductance blockade during DNA translocation) and the process that captures DNA into the nanopore, without affecting the duration time of the translocations. Most striking is a strong plasmon-induced enhancement of the rate of DNA translocation events in lithium chloride (LiCl, already 10-fold enhancement at a few mW of laser power). This provides a means to utilize the excellent spatiotemporal resolution of DNA interrogations with nanopores in LiCl buffers, which is known to suffer from low event rates. We propose a mechanism based on plasmon-induced local heating and thermophoresis as explanation of our observations. PMID:25347403

  17. A FIB induced boiling mechanism for rapid nanopore formation

    PubMed Central

    Das, K; Freund, J B; Johnson, H T

    2015-01-01

    Focused ion beam (FIB) technology is widely used to fabricate nanopores in solid-state membranes. These nanopores have desirable thermomechanical properties for applications such as high-throughput DNA sequencing. Using large scale molecular dynamics simulations of the FIB nanopore formation process, we show that there is a threshold ion delivery rate above which the mechanism underlying nanopore formation changes. At low rates nanopore formation is slow, with the rate proportional to the ion flux and therefore limited by the sputter rate of the target material. However, at higher fluxes nanopores form via a thermally dominated process, consistent with an explosive boiling mechanism. In this case, mass is rapidly rearranged via bubble growth and coalescence, much more quickly than would occur during sputtering. This mechanism has the potential to greatly speed up nanopore formation. PMID:24356374

  18. Mechanical Properties and Fracture Behavior of Nanoporous Au

    SciTech Connect

    Biener, J; Hodge, A M; Wang, Y M; Hayes, J R; Hamza, A V

    2005-06-16

    Nanoporous metals have recently attracted considerable interest fueled by potential sensor and actuator applications. From a material science point of view, one of the key issues in this context is the synthesis of nanoporous metals with both high tensile and compressive strength. Nanoporous gold (np-Au) has been suggested as a candidate material for this application due to its monolithic character. The material can be synthesized by electrochemically-driven dealloying of Ag-Au alloys, and exhibits an open sponge-like structure of interconnecting ligaments with a typical pore size distribution on the nanometer length scale. However, besides the observation of a ductile-brittle transition very little is known about the mechanical behavior of this material. Here, we present our results regarding the mechanical properties and the fracture behavior of np-Au. Depth-sensing nanoindentation reveals that the yield strength of np-Au is almost one order of magnitude higher than the value predicted by scaling laws developed for macroscopic open-cell foams. The unexpectedly high value of the yield strength indicates the presence of a distinct size effect of the mechanical properties due to the sub-micron dimensions of the ligaments, thus potentially opening a door to a new class of high yield strength--low density materials. The failure mechanism of np-Au under tensile stress was evaluated by microscopic examination of fracture surfaces using scanning electron microscopy. On a macroscopic level, np-Au is a very brittle material. However, microscopically np-Au is very ductile as ligaments strained by as much as 200% can be observed in the vicinity of crack tips. Cell-size effects on the microscopic failure mechanism were studied by annealing experiments whereby increasing the typical pore size/ligament diameter from {approx}100 nm to {approx}1{micro}m.

  19. Rational engineering of nanoporous anodic alumina optical bandpass filters.

    PubMed

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

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  20. Ageing effect in spray pyrolysed B:SnO{sub 2} thin films for LPG sensing

    SciTech Connect

    Skariah, Benoy E-mail: dr.boben1@gmail.com; Thomas, Boben E-mail: dr.boben1@gmail.com

    2014-10-15

    For LPG sensing, boron doped (0.2 to 0.8 wt. %) polycrystalline tin oxide thin films are deposited by spray pyrolysis in the temperature range 325 - 430 °C. Sensor response of 56 % is achieved for 1000 ppm of LPG, at an operating temperature of 350 °C. The effects of ageing under ambient conditions on the sensor response are investigated for a storage period of six years. Ageing increases the film resistance but the gas response is lowered. XRD, SEM, FESEM, FTIR and XPS are utilized for structural, morphological and compositional charaterisations.

  1. Detection of urea-induced internal denaturation of dsDNA using solid-state nanopores.

    PubMed

    Singer, Alon; Kuhn, Heiko; Frank-Kamenetskii, Maxim; Meller, Amit

    2010-11-17

    The ability to detect and measure dsDNA thermal fluctuations is of immense importance in understanding the underlying mechanisms responsible for transcription and replication regulation. We describe here the ability of solid-state nanopores to detect sub-nanometer changes in DNA structure as a result of chemically enhanced thermal fluctuations. In this study, we investigate the subtle changes in the mean effective diameter of a dsDNA molecule with 3-5 nm solid-state nanopores as a function of urea concentration and the DNA's AT content. Our studies reveal an increase in the mean effective diameter of a DNA molecule of approximately 0.6 nm at 8.7 M urea. In agreement with the mechanism of DNA local denaturation, we observe a sigmoid dependence of these effects on urea concentration. We find that the translocation times in urea are markedly slower than would be expected if the dynamics were governed primarily by viscous effects. Furthermore, we find that the sensitivity of the nanopore is sufficient to statistically differentiate between DNA molecules of nearly identical lengths differing only in sequence and AT content when placed in 3.5 M urea. Our results demonstrate that nanopores can detect subtle structural changes and are thus a valuable tool for detecting differences in biomolecules' environment. PMID:21339599

  2. Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

    NASA Astrophysics Data System (ADS)

    Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

    2016-06-01

    Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

  3. Nanopore-Based Conformational Analysis of a Viral RNA Drug Target

    PubMed Central

    Stoloff, Daniel H.; Rynearson, Kevin D.; Hermann, Thomas; Wanunu, Meni

    2016-01-01

    Nanopores are single-molecule sensors that show exceptional promise as a biomolecular analysis tool by enabling label-free detection of small amounts of sample. In this paper, we demonstrate that nanopores are capable of detecting the conformation of an antiviral RNA drug target. The hepatitis C virus uses an internal ribosome entry site (IRES) motif in order to initiate translation by docking to ribosomes in its host cell. The IRES is therefore a viable and important drug target. Drug-induced changes to the conformation of the HCV IRES motif, from a bent to a straight conformation, have been shown to inhibit HCV replication. However, there is presently no straightforward method to analyze the effect of candidate small-molecule drugs on the RNA conformation. In this paper, we show that RNA translocation dynamics through a 3 nm diameter nanopore is conformation-sensitive by demonstrating a difference in transport times between bent and straight conformations of a short viral RNA motif. Detection is possible because bent RNA is stalled in the 3 nm pore, resulting in longer molecular dwell times than straight RNA. Control experiments show that binding of a weaker drug does not produce a conformational change, as consistent with independent fluorescence measurements. Nanopore measurements of RNA conformation can thus be useful for probing the structure of various RNA motifs, as well as structural changes to the RNA upon small-molecule binding. PMID:24861167

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Hybrid pore formation by directed insertion of alpha hemolysin into solid-state nanopores

    PubMed Central

    Hall, Adam R.; Scott, Andrew; Rotem, Dvir; Mehta, Kunal K.; Bayley, Hagan; Dekker, Cees

    2011-01-01

    Nanopores hold great potential for genomic screening and sequencing technologies. Thus far, most studies have concentrated on the Staphylococcus aureus pore-forming protein alpha hemolysin (αHL)1 and artificial pores in solid-state (SS) membranes2. While biological pores offer an atomically precise structure3 and genetic engineering potential4, SS-pores offer durability, size and shape control5 and integratability. Each system, however, also has significant limitations: αHL is difficult to integrate because it relies on delicate lipid bilayers for mechanical support, and the fabrication of SS-pores at precise dimensions remains challenging. Here we show that these limitations may be overcome by inserting a single αHL pore into a SS-nanopore. A double-stranded DNA attached to a protein pore is threaded into a SS-nanopore by electrophoretic translocation. Protein insertion is observed in 30-40% of our attempts and translocation of single-stranded DNA demonstrates that the hybrid nanopore remains functional. The resulting hybrid structure offers a platform to create wafer-scale device arrays for genomic analysis including sequencing6. PMID:21113160

  6. Method for making nanoporous hydrophobic coatings

    DOEpatents

    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.

  7. Temperature dependence of fluid transport in nanopores

    NASA Astrophysics Data System (ADS)

    Xu, Baoxing; Wang, Binglei; Park, Taehyo; Qiao, Yu; Zhou, Qulan; Chen, Xi

    2012-05-01

    Understanding the temperature-dependent nanofluidic transport behavior is critical for developing thermomechanical nanodevices. By using non-equilibrium molecular dynamics simulations, the thermally responsive transport resistance of liquids in model carbon nanotubes is explored as a function of the nanopore size, the transport rate, and the liquid properties. Both the effective shear stress and the nominal viscosity decrease with the increase of temperature, and the temperature effect is coupled with other non-thermal factors. The molecular-level mechanisms are revealed through the study of the radial density profile and hydrogen bonding of confined liquid molecules. The findings are verified qualitatively with an experiment on nanoporous carbon.

  8. Observation of ionic Coulomb blockade in nanopores

    NASA Astrophysics Data System (ADS)

    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.

  9. Monolithic aerogels with nanoporous crystalline phases

    NASA Astrophysics Data System (ADS)

    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.

  10. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  11. The use of PEEK nanorod arrays for the fabrication of nanoporous surfaces under high temperature: SiNx example.

    PubMed

    Martín, Jaime; Martín-González, Marisol

    2012-09-21

    Large area silicon nitride (SiN(x)) nanoporous surfaces are fabricated using poly(ether-ether-ketone) (PEEK) nanorod arrays as a template. The procedure involves manipulation of nanoporous anodic aluminum oxide (AAO) templates in order to form an ordered array of PEEK nanopillars with high temperature resistant characteristics. In this context, self-ordered AAO templates are infiltrated with PEEK melts via the "precursor film" method. Once the melts have been crystallized in the porous structure of AAO, the basis alumina layer is removed, yielding an ordered array of PEEK nanopillars. The resulting structure is a high temperature and chemical resistant polymeric nanomold, which can be utilized in the synthesis of nanoporous materials under aggressive conditions. Such conditions are high temperatures (up to 320 °C), vacuum, or extreme pH. For example, SiN(x) nanopore arrays have been grown by plasma enhanced chemical vapor deposition at 300 °C, which can be of interest as mold for nanoimprint lithography, due to its hardness and low surface energy. The SiN(x) nanopore array portrays the same characteristics as the original AAO template: 120 nm diameter pores and an interpore distance of 430 nm. Furthermore, the aspect ratio of the SiN(x) nanopores can be tuned by selecting an AAO template with appropriate conditions. The use of PEEK as a nanotemplate extends the applicability of polymeric nanopatterns into a temperature regime up to now not accessible and opens up the simple fabrication of novel nanoporous inorganic surfaces. PMID:22854871

  12. Substrate dependant capacitive performance of spray pyrolysed titanium oxide (TiO2) thin films

    NASA Astrophysics Data System (ADS)

    Fugare, B. Y.; Ingole, R. S.; Ambare, R. C.; Lokhande, B. J.

    2016-04-01

    Using 60 ml, 0.06 M aqueous solution of potassium titanium oxalate (pto), thin films of titanium oxide were prepared by using well known spray pyrolysis technique. Depositions of the films carried out at 723° K by maintain the spray rate 12 Cc/min. prepared thin films were characterized structurally, morphologically and electrochemically. Sample shows tetragonal crystal structure with rutile as prominent phase at very low deposition temperature. SEM morphology shows porous, dense, nanorods and nanoplates like morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The specific capacitance values observed from cyclic voltammetery in 1 M NaOH are 2497.19, 29.60, 424.22 F/g. for the electrode deposited on copper, FTO and stainless steel (SS) respectively. Charge discharge behavior was observed for the samples deposited on stainless steel gives specific energy (SE), specific power (SP) and efficiency (η) are 43.25 Wh/kg, 35.25 kW/kg and 98.22 % respectively. Impedance study was carried out in the frequency range 1 mHz to 1 MHz exhibits very less internal resistance 1.066 Ohm for the deposited electrode.

  13. Device properties of nanopore PN junction Si for photovoltaic application

    NASA Astrophysics Data System (ADS)

    Jin, Hyunjong; Chang, Te Wei; Liu, Logan Gang

    2011-09-01

    Improvement of energy conversion efficiency of solar cells has led to innovative approaches, in particular the introduction of nanopillar photovoltaics [1]. Previous work on nanopillar Si photovoltaic has shown broadband reduction in optical reflection and enhancement of absorption [2]. Radial or axial PN junctions [3, 4] have been of high interest for improved photovoltaic devices. However, with the PN junction incorporated as part of the pillar, the discreteness of individual pillar requires additional conductive layer that would electrically short the top of each pillar for efficient carrier extraction. The fragile structure of the surface pillars would also require a protection layer for possible mechanical scratch to prevent pillars from breaking. Any additional layer that is applied, either for electrical contact or for mechanical properties may introduce additional recombination sites and also reduce the actual light absorption by the photovoltaic material. In this paper, nanopore Si photovoltaics that not only provides the advantages but also addresses the challenges of nanopillers is demonstrated. PN junction substrate of 250 nm thick N-type polycrystalline Si on P-type Si wafer is prepared. The nanopore structure is formed by using anodized aluminum oxide (AAO) as an etching mask against deep reactive ionic etching (DRIE). The device consists of semi-ordered pores of ~70 nm diameter.

  14. Translocation of α-helix chains through a nanopore

    NASA Astrophysics Data System (ADS)

    Yang, Zhiyong; Li, Shiben; Zhang, Linxi; ur Rehman, Ateeq; Liang, Haojun

    2010-10-01

    The translocation of α-helix chains through a nanopore is studied through Langevin dynamics simulations. The α-helix chains exhibit several different characteristics about their average translocation times and the α-helix structures when they transport through the nanopores under the driving forces. First, the relationship between average translocation times τ and the chain length N satisfies the scaling law, τ ˜Nα, and the scaling exponent α depends on the driving force f for the small forces while it is close to the Flory exponent (ν) in the other force regions. For the chains with given chain lengths, it is observed that the dependence of the average translocation times can be expressed as τ ˜f-1/2 for the small forces while can be described as τ ˜f in the large force regions. Second, for the large driving force, the average number of α-helix structures Nh decreases first and then increases in the translocation process. The average waiting time of each bead, especially of the first bead, is also dependent on the driving forces. Furthermore, an elasticity spring model is presented to reasonably explain the change of the α-helix number during the translocation and its elasticity can be locally damaged by the large driving forces. Our results demonstrate the unique behaviors of α-helix chains transporting through the pores, which can enrich our insights into and knowledge on biopolymers transporting through membranes.

  15. Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors.

    PubMed

    Lang, Xingyou; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

    2011-04-01

    Electrochemical supercapacitors can deliver high levels of electrical power and offer long operating lifetimes, but their energy storage density is too low for many important applications. Pseudocapacitive transition-metal oxides such as MnO(2) could be used to make electrodes in such supercapacitors, because they are predicted to have a high capacitance for storing electrical charge while also being inexpensive and not harmful to the environment. However, the poor conductivity of MnO(2) (10(-5)-10(-6) S cm(-1)) limits the charge/discharge rate for high-power applications. Here, we show that hybrid structures made of nanoporous gold and nanocrystalline MnO(2) have enhanced conductivity, resulting in a specific capacitance of the constituent MnO(2) (~1,145 F g(-1)) that is close to the theoretical value. The nanoporous gold allows electron transport through the MnO(2), and facilitates fast ion diffusion between the MnO(2) and the electrolytes while also acting as a double-layer capacitor. The high specific capacitances and charge/discharge rates offered by such hybrid structures make them promising candidates as electrodes in supercapacitors, combining high-energy storage densities with high levels of power delivery. PMID:21336267

  16. Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Lang, Xingyou; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

    2011-04-01

    Electrochemical supercapacitors can deliver high levels of electrical power and offer long operating lifetimes, but their energy storage density is too low for many important applications. Pseudocapacitive transition-metal oxides such as MnO2 could be used to make electrodes in such supercapacitors, because they are predicted to have a high capacitance for storing electrical charge while also being inexpensive and not harmful to the environment. However, the poor conductivity of MnO2 (10-5-10-6 S cm-1) limits the charge/discharge rate for high-power applications. Here, we show that hybrid structures made of nanoporous gold and nanocrystalline MnO2 have enhanced conductivity, resulting in a specific capacitance of the constituent MnO2 (~1,145 F g-1) that is close to the theoretical value. The nanoporous gold allows electron transport through the MnO2, and facilitates fast ion diffusion between the MnO2 and the electrolytes while also acting as a double-layer capacitor. The high specific capacitances and charge/discharge rates offered by such hybrid structures make them promising candidates as electrodes in supercapacitors, combining high-energy storage densities with high levels of power delivery.

  17. New Graphene Form of Nanoporous Monolith for Excellent Energy Storage.

    PubMed

    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. PMID:26641709

  18. Characteristics of shear layer with pyrolysing coal particles in one of the streams

    SciTech Connect

    Gollahalli, S.R.; Butuk, N.

    1998-07-01

    This article presents an experimental study of the growth and structure of a two-dimensional shear layer formed by two gas streams, one of which contained coal particles undergoing pyrolysis. Apparatus consisted of a low speed shear layer wind-tunnel designed to generate two gas streams, initially with uniform velocity profiles and isotropic turbulence, which mix at the end of a splitter plate. A fluidized bed injector system was used to introduce bituminous coal particles into one of the streams which was heated to cause their pyrolysis. The test section was optically accessible. The instrumentation included thermocouple, Pitot tube, laser velocimeter, and gas analyzers. Velocity profiles, temperature profiles, shear layer growth rate parameter, and turbulent intensity measurements were obtained. Results indicate that the presence of coal particles affect the velocity and decreases the shear layer growth rate (visible and vorticity thickness) significantly; however, the mass addition due to pyrolysis alone does not change the shear layer characteristics significantly.

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

    PubMed Central

    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

  20. Characterization and study of antibacterial activity of spray pyrolysed ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Manoharan, C.; Pavithra, G.; Bououdina, M.; Dhanapandian, S.; Dhamodharan, P.

    2016-08-01

    Aluminum-doped zinc oxide (ZnO:Al) thin films were deposited onto glass substrates using spray pyrolysis technique with the substrate temperature of 400 °C. X-ray diffraction analysis indicated that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along (002) direction. Surface morphology of the films obtained by scanning electron microscopy showed that the grains were of nanoscale size with porous nature for 6 at.% of Al. Atomic force microscopy observations revealed that the particles size and surface roughness of the films decreased with Al-doping. Optical measurements indicated that ZnO:Al (6 at.%) exhibited a band gap of 3.11 eV, which is lower than that of pure ZnO film, i.e. 3.42 eV. Photoluminescence analysis showed weak NBE emission at 396 nm for Al-doped films. The low resistivity, high hall mobility and carrier concentration values were obtained at a doping ratio of 6 at.% of Al. The effective incorporation of 6 at.% of Al into ZnO lattice by occupying Zn sites yielded a well-pronounced antibacterial activity against Staphylococcus aureus.

  1. Characterization and study of antibacterial activity of spray pyrolysed ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Manoharan, C.; Pavithra, G.; Bououdina, M.; Dhanapandian, S.; Dhamodharan, P.

    2015-08-01

    Aluminum-doped zinc oxide (ZnO:Al) thin films were deposited onto glass substrates using spray pyrolysis technique with the substrate temperature of 400 °C. X-ray diffraction analysis indicated that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along (002) direction. Surface morphology of the films obtained by scanning electron microscopy showed that the grains were of nanoscale size with porous nature for 6 at.% of Al. Atomic force microscopy observations revealed that the particles size and surface roughness of the films decreased with Al-doping. Optical measurements indicated that ZnO:Al (6 at.%) exhibited a band gap of 3.11 eV, which is lower than that of pure ZnO film, i.e. 3.42 eV. Photoluminescence analysis showed weak NBE emission at 396 nm for Al-doped films. The low resistivity, high hall mobility and carrier concentration values were obtained at a doping ratio of 6 at.% of Al. The effective incorporation of 6 at.% of Al into ZnO lattice by occupying Zn sites yielded a well-pronounced antibacterial activity against Staphylococcus aureus.

  2. The distribution and association of trace elements in the bitumen, kerogen and pyrolysates from New Albany oil shale

    SciTech Connect

    Mercer, G.E.

    1992-01-01

    The distribution and association of trace elements in bitumen, kerogen and pyrolysates from New Albany oil shale were investigated using instrumental neutron activation analysis (INAA), x-ray diffraction (XRD), electron microprobe x-ray fluorescence (EMP-XRF), liquid chromatography, ultra-violet spectroscopy and mass spectrometry. The kerogen was found to contain several HCl/HF resistant minerals (determined by XRD), including pyrite, marcasite, chalcopyrite, rutile, and anatase, and the neoformed mineral ralstonite. Kerogens (prepared at UNOCAL, CA) which were fractionated in an aqueous ZnBr[sub 2] solution were found to contain [approximately]20% less acid-resistant minerals than traditional' HCl/HF isolated kerogens and were contaminated with Zn and Br. Kerogens (prepared at the University of Munich) treated with SnCl[sub 2]/H[sub 3]PO[sub 4] at 150-270[degrees]C (Kiba) and/or SnCl[sub 2]/HCl at 110[degrees]C were found to contain <10% of their original pyrite/marcasite (FeS[sub 2]), but were contaminated with large amounts of Sn. The Kiba treatment also appeared to demetallate Ni(II) and VO(II) porphyrins. The inorganic and organic associations of trace elements in New Albany kerogen were studied by analysis of kerogen fractions and a mineral residue ([approximately]85% FeS[sub 2]) obtained through density separations. The degree of association of several elements (As, Co, Mn, Mo, Ni, Sb, and Se) with FeS[sub 2] was determined through the analysis of individual mineral grains by EMP-XRF and by analysis of the mineral residue treated with dilute HNO[sub 3] to remove FeS[sub 2]. These studies indicated that essentially all of the V and [approximately]95% of the Ni present in New Albany kerogen is organically associated. Methods which are designed to account for the inorganic associations of trace elements in kerogens, including methods based on physical methods of separation, chemical removal of FeS[sub 2], EMP-XRF and low temperature ashing, are compared.

  3. Design and fabrication of asymmetric nanopores using pulsed PECVD

    NASA Astrophysics Data System (ADS)

    Kelkar, Sanket S.

    Manipulating matter at nanometric length scales is important for many electronic, chemical and biological applications. Structures such as nanopores demonstrate a phenomenon known as hindered transport which can be exploited in analytical applications such as DNA sequencing, ionic transistors, and molecular sieving. Precisely controlling the size, geometry and surface characteristics of the nanopores is important for realizing these applications. In this work, we employ relatively large template structures (˜ 100 nm) produced by track-etching or electron beam lithography. The pore size is then reduced to the desired level by deposition of material using pulsed plasma enhanced chemical vapor deposition (PECVD). Pulsed PECVD has been developed as a high throughput alternative to atomic layer deposition (ALD) to deliver self-limiting growth of thin films. The goal of this thesis is to extend the application of pulsed PECVD to fabricate asymmetric nanopores. In contrast to ALD, pulsed PECVD does not result in perfectly conformal deposition profiles, and predicting the final nanostructure is more complicated. A two dimensional feature scale model was developed to predict film profile evolution. The model was built in COMSOL, and is based on a diffusion reaction framework with a spatially varying Knudsen diffusion coefficient to account for the molecular transport inside the features. A scaling analysis was used to account for ALD exposure limitations that commonly occur when coating these extremely high aspect ratio features. The model was verified by cross-section microscopy of deposition profiles on patterned cylinders and trenches. The model shows that it is possible to obtain unique nanopore morphologies in pulsed PECVD that are distinct from either steady state deposition processes such as physical vapor deposition (PVD) or conventional ALD. Polymeric track etched (TE) membrane supports with a nominal size of 100 nm were employed as model template structures to

  4. Effects of the surface characteristics of nanoporous titanium oxide films on Ti-24Nb-4Zr-8Sn alloy on the initial adhesion of osteoblast-like MG-63 cells

    PubMed Central

    HAO, YUQUAN; LI, SHUJUN; HAN, XUESONG; HAO, YULIN; AI, HONGJUN

    2013-01-01

    The aim of the present study was to investigate the effects of the surface characteristics of nanoporous titanium oxide films, formed by anodization on Ti-24Nb-4Zr-8Sn (Ti2448) alloy, on the early adhesion of osteoblast-like MG-63 cells. Nanoporous titanium oxide films with two different pore sizes (30 and 90 nm) were formed by anodization in NH4F solution on Ti2448 alloy. The surface roughness of the nanoporous titanium oxide films was determined using a Surftest Formtracer and field emission scanning electron microscopy (FESEM). Cell viability was evaluated at different time points using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To investigate the regulatory mechanisms involved in the focal adhesion of osteoblasts to Ti2448 alloy, we quantified the expression levels of integrin β1 and paxillin mRNAs on the nanoporous titanium oxide films during early osteoblast adhesion using real-time RT-PCR. Samples with a 30-nm nanoporous film exhibited a greater number of overlapping microporous structures with microprojections compared with the 90-nm nanoporous film samples. The MTT assay indicated that cell viability on the 30-nm nanoporous surface following 24 and 48 h of cell culture was higher than those observed on the unanodized control and 90-nm nanoporous surfaces. Integrin β1 mRNA expression levels on the 30-nm nanoporous surface following cell culture for 48 h were also significantly higher compared with those on the unanodized control and 90-nm nanoporous surfaces. The results demonstrated that a 30-nm nanoporous titanium oxide film on Ti2448 alloy may provide the optimum bioactive implant surface for the initial adhesion of osteoblasts. PMID:23935754

  5. Effects of the surface characteristics of nanoporous titanium oxide films on Ti-24Nb-4Zr-8Sn alloy on the initial adhesion of osteoblast-like MG-63 cells.

    PubMed

    Hao, Yuquan; Li, Shujun; Han, Xuesong; Hao, Yulin; Ai, Hongjun

    2013-07-01

    The aim of the present study was to investigate the effects of the surface characteristics of nanoporous titanium oxide films, formed by anodization on Ti-24Nb-4Zr-8Sn (Ti2448) alloy, on the early adhesion of osteoblast-like MG-63 cells. Nanoporous titanium oxide films with two different pore sizes (30 and 90 nm) were formed by anodization in NH4F solution on Ti2448 alloy. The surface roughness of the nanoporous titanium oxide films was determined using a Surftest Formtracer and field emission scanning electron microscopy (FESEM). Cell viability was evaluated at different time points using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To investigate the regulatory mechanisms involved in the focal adhesion of osteoblasts to Ti2448 alloy, we quantified the expression levels of integrin β1 and paxillin mRNAs on the nanoporous titanium oxide films during early osteoblast adhesion using real-time RT-PCR. Samples with a 30-nm nanoporous film exhibited a greater number of overlapping microporous structures with microprojections compared with the 90-nm nanoporous film samples. The MTT assay indicated that cell viability on the 30-nm nanoporous surface following 24 and 48 h of cell culture was higher than those observed on the unanodized control and 90-nm nanoporous surfaces. Integrin β1 mRNA expression levels on the 30-nm nanoporous surface following cell culture for 48 h were also significantly higher compared with those on the unanodized control and 90-nm nanoporous surfaces. The results demonstrated that a 30-nm nanoporous titanium oxide film on Ti2448 alloy may provide the optimum bioactive implant surface for the initial adhesion of osteoblasts. PMID:23935754

  6. Carbon dioxide sorption in a nanoporous octahedral molecular sieve

    NASA Astrophysics Data System (ADS)

    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.

  7. Microscopic failure behavior of nanoporous Gold

    SciTech Connect

    Biener, J; Hodge, A; Hamza, A

    2005-01-10

    Nanoporous metals have recently attracted considerable interest fueled by potential sensor and actuator applications. One of the key issues in this context is the synthesis of high yield strength materials. Nanoporous Au (np-Au) has been suggested as a candidate due to its monolithic character. The material can be synthesized by dealloying Ag-Au alloys, and exhibits an open sponge-like morphology of interconnecting Au ligaments with a typical pore size distribution on the nanometer length scale. Unfortunately, very little is known about the mechanical properties of np-Au besides a length-scale dependent ductile-brittle transition. A key question in this context is: what causes the macroscopic brittleness of np-Au? Is the normal dislocation-mediated plastic deformation suppressed in nanoscale Au ligaments, or is the brittleness a consequence of the macroscopic morphology? Here, we report on the fracture behavior of nanoporous Au studied by scanning electron microscopy. Specifically, we demonstrate the microscopic ductility of nanometer-sized Au ligaments. The observed fracture behavior seems to be general for nanoporous metals, and can be understood in terms of simple fuse networks.

  8. Ion transport through a graphene nanopore

    PubMed Central

    Hu, Guohui; Mao, Mao; Ghosal, Sandip

    2012-01-01

    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 nonuniformity of the ion distribution gives rise to an electric pressure which drives vortical motions in the fluid if the electric field is sufficiently strong to overcome the influence of viscosity and thermal fluctuations. The relative importance of hydrodynamic transport and thermal fluctuations in determining the pore conductivity is investigated. A second important effect that is observed is the mass transport of water through the nanopore, with an average velocity proportional to the applied voltage and independent of the pore diameter. The flux arises as a consequence of the asymmetry in the ion distribution which can be attributed to differing mobilities of the sodium and chlorine ions, and, to the polarity of water molecules. The accumulation of liquid molecules in the vicinity of the nanopore due to reorientation of the water dipoles by the local electric field is seen to result in a local increase in the liquid density. Results confirm that the electric conductance is proportional to the nanopore diameter for the parameter regimes that we simulated. The occurrence of fluid vortices is found to result in an increase in the effective electrical conductance. PMID:22962262

  9. Enzyme Specific Activity in Functionalized Nanoporous Supports

    SciTech Connect

    Lei, Chenghong; Soares, Thereza A.; Shin, Yongsoon; Liu, Jun; Ackerman, Eric J.

    2008-03-26

    Enzyme specific activity can be increased or decreased to a large extent by changing protein loading density in functionalized nanoporous support, where organophosphorus hydrolase can display a constructive orientation and thus leave a completely open entrance for substrate even at higher protein loading density, but glucose oxidase can not.

  10. Cell encapsulation and oxygenation in nanoporous microcontainers

    PubMed Central

    Kwon, Joonbum; Liu, Li; Su, Yang; Nemani, Krishnamurthy; Trivedi, Krutarth; Cui, Yonghao; Vachha, Behroze; Mason, Ralph; Hu, Wenchuang; Lee, Jeong-Bong

    2010-01-01

    With strides in stem cell biology, cell engineering and molecular therapy, the transplantation of cells to produce therapeutic molecules endogenously is an attractive and achievable alternative to the use of exogenous drugs. The encapsulation of such cell transplants in semi-permeable, nanoporous constructs is often required to protect them from immune attack and to prevent their proliferation in the host. However, effective graft immunoisolation has been mostly elusive owing to the absence of a high-throughput method to create precisely controlled, high-aspect-ratio nanopores. To address the clinical need for effective cell encapsulation and immunoisolation, we devised a biocompatible cell-encapsulating microcontainer and a method to create highly anisotropic nanopores in the micro-container’s surface. To evaluate the efficacy of these nanopores in oxygenating the encapsulated cells, we engineered 9L rat glioma cells to bioluminesce under hypoxic conditions. The methods described above should aid in evaluating the long term survival and efficacy of cellular grafts. PMID:19629700

  11. Ion transport and selectivity in biomimetic nanopores with pH-tunable zwitterionic polyelectrolyte brushes

    NASA Astrophysics Data System (ADS)

    Zeng, Zhenping; Yeh, Li-Hsien; Zhang, Mingkan; Qian, Shizhi

    2015-10-01

    Inspired by nature, functionalized nanopores with biomimetic structures have attracted growing interests in using them as novel platforms for applications of regulating ion and nanoparticle transport. To improve these emerging applications, we study theoretically for the first time the ion transport and selectivity in short nanopores functionalized with pH tunable, zwitterionic polyelectrolyte (PE) brushes. In addition to background salt ions, the study takes into account the presence of H+ and OH- ions along with the chemistry reactions between functional groups on PE chains and protons. Due to ion concentration polarization, the charge density of PE layers is not homogeneously distributed and depends significantly on the background salt concentration, pH, grafting density of PE chains, and applied voltage bias, thereby resulting in many interesting and unexpected ion transport phenomena in the nanopore. For example, the ion selectivity of the biomimetic nanopore can be regulated from anion-selective (cation-selective) to cation-selective (anion-selective) by diminishing (raising) the solution pH when a sufficiently small grafting density of PE chains, large voltage bias, and low background salt concentration are applied.

  12. Rapid and label-free single-nucleotide discrimination via an integrative nanoparticle-nanopore approach.

    PubMed

    Ang, Yan Shan; Yung, Lin-Yue Lanry

    2012-10-23

    Single-nucleotide polymorphism (SNP) is an important biomarker for disease diagnosis, treatment monitoring, and development of personalized medicine. Recent works focused primarily on ultrasensitive detection, while the need for rapid and label-free single-nucleotide discrimination techniques, which are crucial criteria for translation into clinical applications, remains relatively unexplored. In this work, we developed a novel SNP detection assay that integrates two complementary nanotechnology systems, namely, a highly selective nanoparticle-DNA detection system and a single-particle sensitive nanopore readout platform, for rapid detection of single-site mutations. Discrete nanoparticle-DNA structures formed in the presence of perfectly matched (PM) or single-mismatched (SM) targets exhibited distinct size differences, which were resolved on a size-tunable nanopore platform to generate corresponding "yes/no" readout signals. Leveraging the in situ reaction monitoring capability of the nanopore platform, we demonstrated that real-time single-nucleotide discrimination of a model G487A mutation, responsible for glucose-6-phosphate dehydrogenase deficiency, can be achieved within 30 min with no false positives. Semiquantification of DNA samples down to picomolar concentration was carried out using a simple parameter of particle count without the need for sample labeling or signal amplification. The unique combination of nanoparticle-based detection and nanopore readout presented in this work brings forth a rapid, specific, yet simple biosensing strategy that can potentially be developed for point-of-care application. PMID:22994459

  13. Integrated Nanopore Detectors in a Standard Complementary Metal-Oxide-Semiconductor Process

    NASA Astrophysics Data System (ADS)

    Uddin, Ashfaque; Chen, Chin-Hsuan; Yemenicioglu, Sukru; Milaninia, Kaveh; Corigliano, Ellie; Varma, Madoo; Theogarajan, Luke

    2012-02-01

    High-bandwidth and low-noise nanopore sensor and detection electronics are crucial in achieving single-DNA base resolution. A potential way to accomplish this goal is to integrate solid-state nanopores within a CMOS platform, in close proximity to the biasing electrodes and custom-designed amplifier electronics. Here we report the development of solid-state nanopore devices in a commercial CMOS potentiostat chip implemented in On-Semiconductor's 0.5 micron technology. By using post-CMOS micromachining, a free-standing oxide membrane and electrodes are fabricated utilizing the N+ polysilicon/oxide/N+ polysilicon capacitor structure available in the aforementioned process. Nanopores with sub-5 nm diameter are drilled in the membrane using a Transmission Electron Microscope. The integrity of pores is validated by measuring current-voltage and noise characteristics. DNA translocation experiments are also performed utilizing these on-chip pores. In addition, electrical tests performed on the CMOS potentiostat circuitry show that the post-CMOS micromachining process does not have any detrimental effect on the CMOS circuitry.

  14. Nanopore patterning using Al2O3 hard masks on SOI substrates

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Goryll, Michael

    2015-07-01

    Aluminum oxide Al2O3, deposited using amorphous atomic layer deposition (ALD), is a very promising material to be utilized as a hard mask for nano-patterning. We used an aluminum oxide hard mask on a silicon-on-insulator (SOI) substrate to implement a sub-100 nm nanopore process. The transfer of nanoscale patterns via dry etching of the Al2O3 thin film was investigated by comparing etch profiles, etch rates, and selectivity of Al2O3 over PMMA resist, using different gas chemistries such as Cl2, Ar, Ar/BCl3 mixtures, and BCl3 plasma. A selectivity of 1:4 was observed using an inductively coupled plasma reactive ion etching (ICP-RIE) tool with BCl3 plasma, and the sub-100 nm nanopore patterns were anisotropically transferred to the alumina layer from a 250 nm PMMA layer. The dense and inert Al2O3 hard mask showed exceptional etch selectivity to Si and SiO2, which allowed the subsequent transfer of the nanopore patterns into the 340 nm-thick Si device layer and made it possible to attempt etching the 1 μm-thick buried oxide (BOX) layer. Using chlorine chemistry, nanopores patterned in the Si device layer showed excellent anisotropy while preserving the original pattern dimensions. The process demonstrated is ideally suited for patterning high aspect ratio nanofluidic structures.

  15. Nanoporous separators for supercapacitor using activated carbon monolith electrode from oil palm empty fruit bunches

    SciTech Connect

    Nor, N. S. M. Deraman, M. Omar, R. Basri, N. H.; Dolah, B. N. M.; Taer, E.; Awitdrus,; Farma, R.

    2014-02-24

    Activated porous carbon electrode prepared from fibres of oil palm empty fruit bunches was used for preparing the carbon based supercapacitor cells. The symmetrical supercapacitor cells were fabricated using carbon electrodes, stainless steel current collector, H{sub 2}SO{sub 4} electrolyte, and three types of nanoporous separators. Cells A, B and C were fabricated using polypropylene, eggshell membrane, and filter paper, respectively. Electrochemical characterizations data from Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, and Galvanic Charge Discharge techniques showed that specific capacitance, specific power and specific energy for cell A were 122 F g{sup −1}, 177 W kg{sup −1}, 3.42 Wh kg{sup −1}, cell B; 125 F g{sup −1}, 179 W kg{sup −1}, and 3.64 Wh kg{sup −1}, and cell C; 180 F g{sup −1}, 178 W kg{sup −1}, 4.27 Wh kg{sup −1}. All the micrographs from Field Emission Scanning Electron Microscope showed that the different in nanoporous structure of the separators lead to a significant different in influencing the values of specific capacitance, power and energy of supercapacitors, which is associated with the mobility of ion into the pore network. These results indicated that the filter paper was superior than the eggshell membrane and polypropylene nanoporous separators. However, we found that in terms of acidic resistance, polypropylene was the best nanoporous separator for acidic medium.

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

    PubMed

    Lee, Min Kyung; Lee, Jonghwi

    2014-08-01

    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. PMID:24865989

  17. Novel spider-web-like nanoporous networks based on jute cellulose nanowhiskers.

    PubMed

    Cao, Xinwang; Wang, Xianfeng; Ding, Bin; Yu, Jianyong; Sun, Gang

    2013-02-15

    Cellulose nanowhiskers as a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Herein, for the first time, a novel controllable fabrication of spider-web-like nanoporous networks based on jute cellulose nanowhiskers (JCNs) deposited on the electrospun (ES) nanofibrous membrane by simple directly immersion-drying method is reported. Jute cellulose nanowhiskers were extracted from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization. The morphology of JCNs nanoporous networks/ES nanofibrous membrane architecture, including coverage rate, pore-width and layer-by-layer packing structure of the nanoporous networks, can be finely controlled by regulating the JCNs dispersions properties and drying conditions. The versatile nanoporous network composites based on jute cellulose nanowhiskers with ultrathin diameters (3-10 nm) and nanofibrous membrane supports with diameters of 100-300 nm, would be particularly useful for filter applications. PMID:23399256

  18. Advanced Solid State Nanopores Architectures: From Early Cancer Detection to Nano-electrochemistry

    NASA Astrophysics Data System (ADS)

    Bashir, Rashid

    2013-03-01

    Solid-state nanopores (ssNPs) are potentially low-cost and highly scalable technologies for rapid and reliable se-quencing of the human diploid genome for under 1,000. The ssNPs detect ionic current changes while molecules translocate through the pore. Several key challenges must be overcome in order for ssNPs to become ubiquitous in the fields of medical diagnostics and personalized healthcare. One major challenge is to reduce the speed at which DNA translocates through the nanopore from microseconds to milliseconds per nucleotide, enabling reliable identification of single nucleotides. The other major challenge is to improve the sensitivity of the approach requiring new sensing modalities and novel device architectures. In this paper, we review our recent efforts to (i) develop ssNPs for early cancer detection, (ii) to embed graphene electrodes in dielectric nanolaminates to form 3 and 4 terminal nanopore devices, and (iii) we demonstrate a nanopore based structure consisting of stacked graphene and Al2O3 dielectric layers to study electrochemical activity at graphene edges. The electrochemical signal corresponding to the atomically thin graphene layer could also provide a pathway to DNA sequencing. Supported by National Institute of Health.

  19. Pressure pyrolysed non-precious oxygen reduction catalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Nallathambi, Vijayadurga

    2011-12-01

    and increased the porosity, particularly micro and mesopores of the catalysts that led to increased active site density and reduced oxygen transport hindrances respectively. Collaborative efforts with the University of New Mexico facilitated XPS characterization of MNC catalysts. XPS analyses indicated that pyridinic nitrogen sites, present in the edge plane of the catalysts and pyridinic nitrogen coordinated to transition metals correlated to oxygen reduction activity. Further insight into the role of transition metal and the structure of active site was gained through EXAFS measurements, carried out in collaboration with Northeastern University. Electrochemical studies performed in the presence of poisoning anions such as cyanide in alkaline environment indicated a 25% decrease in oxygen reduction activity, suggesting that the metal is part of the active sites and participates in oxygen reduction. In-situ EXAFS analysis of the catalysts indicated the active reaction site for oxygen reduction to be Fe metal coordinated to 4 nitrogen atoms. These low cost MNC catalysts find direct application in Proton Exchange Membrane Fuel cells for transportation applications, where there is a huge drive to improve the economy of the fuel cell by reducing the costs associated with state-of the art platinum-based catalysts.

  20. Investigation of bioactivity and cell effects of nano-porous sol-gel derived bioactive glass film

    NASA Astrophysics Data System (ADS)

    Ma, Zhijun; Ji, Huijiao; Hu, Xiaomeng; Teng, Yu; Zhao, Guiyun; Mo, Lijuan; Zhao, Xiaoli; Chen, Weibo; Qiu, Jianrong; Zhang, Ming

    2013-11-01

    In orthopedic surgery, bioactive glass film coating is extensively studied to improve the synthetic performance of orthopedic implants. A lot of investigations have confirmed that nano-porous structure in bioactive glasses can remarkably improve their bioactivity. Nevertheless, researches on preparation of nano-porous bioactive glasses in the form of film coating and their cell response activities are scarce. Herein, we report the preparation of nano-porous bioactive glass film on commercial glass slide based on a sol-gel technique, together with the evaluation of its in vitro bioactivity through immersion in simulated body fluid and monitoring the precipitation of apatite-like layer. Cell responses of the samples, including attachment, proliferation and osteogenic differentiation, were also investigated using BMSCS (bone marrow derived mesenchymal stem cells) as a model. The results presented here provide some basic information on structural influence of bioactive glass film on the improvement of bioactivity and cellular effects.

  1. Discrimination among protein variants using an unfoldase-coupled nanopore.

    PubMed

    Nivala, Jeff; Mulroney, Logan; Li, Gabriel; Schreiber, Jacob; Akeson, Mark

    2014-12-23

    Previously we showed that the protein unfoldase ClpX could facilitate translocation of individual proteins through the α-hemolysin nanopore. This results in ionic current fluctuations that correlate with unfolding and passage of intact protein strands through the pore lumen. It is plausible that this technology could be used to identify protein domains and structural modifications at the single-molecule level that arise from subtle changes in primary amino acid sequence (e.g., point mutations). As a test, we engineered proteins bearing well-characterized domains connected in series along an ∼700 amino acid strand. Point mutations in a titin immunoglobulin domain (titin I27) and point mutations, proteolytic cleavage, and rearrangement of beta-strands in green fluorescent protein (GFP), caused ionic current pattern changes for single strands predicted by bulk phase and force spectroscopy experiments. Among these variants, individual proteins could be classified at 86-99% accuracy using standard machine learning tools. We conclude that a ClpXP-nanopore device can discriminate among distinct protein domains, and that sequence-dependent variations within those domains are detectable. PMID:25402970

  2. CO2-Selective Nanoporous Metal-Organic Framework Microcantilevers

    PubMed Central

    Yim, Changyong; Lee, Moonchan; Yun, Minhyuk; Kim, Gook-Hee; Kim, Kyong Tae; Jeon, Sangmin

    2015-01-01

    Nanoporous anodic aluminum oxide (AAO) microcantilevers are fabricated and MIL-53 (Al) metal-organic framework (MOF) layers are directly synthesized on each cantilever surface by using the aluminum oxide as the metal ion source. Exposure of the MIL53-AAO cantilevers to various concentrations of CO2, N2, CO, and Ar induces changes in their deflections and resonance frequencies. The results of the resonance frequency measurements for the different adsorbed gas molecules are almost identical when the frequency changes are normalized by the molecular weights of the gases. In contrast, the deflection measurements show that only CO2 adsorption induces substantial bending of the MIL53-AAO cantilevers. This selective deflection of the cantilevers is attributed to the strong interactions between CO2 and the hydroxyl groups in MIL-53, which induce structural changes in the MIL-53 layers. Simultaneous measurements of the resonance frequency and the deflection are performed to show that the diffusion of CO2 into the nanoporous MIL-53 layers occurs very rapidly, whereas the binding of CO2 to hydroxyl groups occurs relatively slowly, which indicates that the adsorption of CO2 onto the MIL-53 layers and the desorption of CO2 from the MIL-53 layers are reaction limited. PMID:26035805

  3. Energy behaviour for DNA translocation through graphene nanopores.

    PubMed

    Alshehri, Mansoor H; Cox, Barry J; Hill, James M

    2015-12-21

    Nanoparticles have considerable promise for many applications in electronics, energy storage, bioscience and biotechnologies. Here we use applied mathematical modelling to exploit the basic principles of mechanics and the 6-12 Lennard-Jones potential function together with the continuum approach, which assumes that a discrete atomic structure can be replaced by an average constant atomic surface density of atoms that is assumed to be smeared over each molecule. We identify a circular hole in a graphene sheet as a nanopore and we consider the molecular interaction energy for both single-strand and double-strand DNA molecules assumed to move through the circular hole in a graphene sheet to determine the radius b of the hole that gives the minimum energy. By minimizing the interaction energy, we observe that the single-strand DNA and double-strand DNA molecules penetrate through a graphene nanopore when the pore radii b> 7.8Å and b> 12.7Å, respectively. Our results can be adopted to offer new applications in the atomic surface processes and electronic sensing. PMID:26449742

  4. Translational dynamics of water in a nanoporous layered silicate

    SciTech Connect

    Nair, Sankar; Chowdhuri, Zema; Peral, Inmaculada; Neumann, Dan A.; Dickinson, L. Charles; Tompsett, Geoffrey; Jeong, Hae-Kwon; Tsapatsis, Michael

    2005-03-01

    Neutron time-of-flight and backscattering spectroscopy have been used to study the translational diffusion of water molecules in the unusual layered material AMH-3, which consists of (zeolitelike) three-dimensionally nanoporous silicate layers spaced by (claylike) interlayer regions. The synthesis of AMH-3 and its characterization by {sup 29}Si NMR, Raman, and infrared spectroscopy, are described. An analysis of quasielastic neutron scattering (QENS) spectra using the random jump diffusion model reveals two translational diffusive motions clearly separated in time scales: a fast process (D{approx}10{sup -9} m{sup 2}/s at 300 K), and a much slower process (D{approx}10{sup -11} m{sup 2}/s at 300 K). Considering the structural model of AMH-3 and the transport properties extracted from the QENS data, it is suggested that the slower motion corresponds to diffusion by water molecules in the interlayer spaces whereas the fast process involves diffusion in the silicate layer. This first investigation of transport phenomena in nanoporous layered silicates like AMH-3 indicates that they have the potential to offer mass transport properties different from zeolite materials and layered clays.

  5. On the anodic aluminium oxide refractive index of nanoporous templates

    NASA Astrophysics Data System (ADS)

    Hierro-Rodriguez, A.; Rocha-Rodrigues, P.; Valdés-Bango, F.; Alameda, J. M.; Jorge, P. A. S.; Santos, J. L.; Araujo, J. P.; Teixeira, J. M.; Guerreiro, A.

    2015-11-01

    In the present study, we have determined the intrinsic refractive index of anodic aluminium oxide, which is originated by the formation of nanoporous alumina templates. Different templates have been fabricated by the conventional two-step anodization procedure in oxalic acid. Their porosities were modified by chemical wet etching allowing the tuning of their effective refractive indexes (air-filled nanopores  +  anodic aluminium oxide). By standard spectroscopic light transmission measurements, the effective refractive index for each different template was extracted in the VIS-NIR region. The determination of the intrinsic anodic aluminium oxide refractive index was performed by using the Maxwell-Garnett homogenization theory. The results are coincident for all the fabricated samples. The obtained refractive index (~1.55) is quite lower (~22%) than the commonly used Al2O3 handbook value (~1.75), showing that the amorphous nature of the anodic oxide structure strongly conditions its optical properties. This difference is critical for the correct design and modeling of optical plasmonic metamaterials based on anodic aluminium oxide nanoporous templates.

  6. Translational dynamics of water in a nanoporous layered silicate

    NASA Astrophysics Data System (ADS)

    Nair, Sankar; Chowdhuri, Zema; Peral, Inmaculada; Neumann, Dan A.; Dickinson, L. Charles; Tompsett, Geoffrey; Jeong, Hae-Kwon; Tsapatsis, Michael

    2005-03-01

    Neutron time-of-flight and backscattering spectroscopy have been used to study the translational diffusion of water molecules in the unusual layered material AMH-3, which consists of (zeolitelike) three-dimensionally nanoporous silicate layers spaced by (claylike) interlayer regions. The synthesis of AMH-3 and its characterization by Si29 NMR, Raman, and infrared spectroscopy, are described. An analysis of quasielastic neutron scattering (QENS) spectra using the random jump diffusion model reveals two translational diffusive motions clearly separated in time scales: a fast process ( Dtilde 10-9m2/s at 300 K), and a much slower process ( Dtilde 10-11m2/s at 300 K). Considering the structural model of AMH-3 and the transport properties extracted from the QENS data, it is suggested that the slower motion corresponds to diffusion by water molecules in the interlayer spaces whereas the fast process involves diffusion in the silicate layer. This first investigation of transport phenomena in nanoporous layered silicates like AMH-3 indicates that they have the potential to offer mass transport properties different from zeolite materials and layered clays.

  7. Nanoporous silica membranes fabricated using multiwalled carbon nanotubes.

    PubMed

    Kim, Hun-Sik; Kwon, Ha Il; Yun, Young Soo; Bak, Hyeonseong; Yoon, Jin-San; Jin, Hyoung-Joon

    2011-05-01

    Nanoporous silica membranes were fabricated using 3-aminopropyltriethoxysilane (APS) and acyl chloride-functionalized multiwalled carbon nanotubes (MWCNTs). The amine groups of silane reacted with the functional groups (e.g., acid chloride) that were attached to the sidewall of the MWCNTs. The APS that was grafted to the sidewall of the MWCNTs was polymerized in order to coat the MWCNTs wall through heating. The thickness of the silica layer on the surface of the MWCNTs was controlled by adjusting the growth time of the SiO2 layer. Approximately 20 nm-sized pores were formed through the removal of the MWCNTs using a simple thermal process, but some traces of the MWCNTs still remained. The porous properties of the nanoporous silica membrane were analyzed from the nitrogen adsorption-desorption isotherms that were obtained using a surface area and porosimetry analyzer. The structure and composition of the silane-modified MWCNTs were characterized using scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. PMID:21780471

  8. Functionalized nanoporous silicas for the immobilization of penicillin acylase

    NASA Astrophysics Data System (ADS)

    Maria Chong, A. S.; Zhao, X. S.

    2004-10-01

    Nanoporous silica materials with uniform pore size and ordered structure have drawn growing interest of researchers since 1990s. A large-pore nanoporous material, SBA-15, was functionalized with organosilanes by co-condensation method in the presence of nonionic triblock copolymer P123 as a template under acidic conditions. The functionalization was demonstrated by using five organosilanes, namely 3-aminopropyltriethoxysilane (APTES), 3-mercaptopropyltrimethoxysilane (MPTMS), phenyltrimethoxysilane (PTMS), vinyltriethoxysilane (VTES), and 4-(triethoxysilyl)butyronitrile (TSBN), which modified the surface properties of the silica materials, enabling the materials to be a promising support for immobilization of biological molecules. The functionalized SBA-15 materials exhibited long-range ordering of two-dimensional hexagonal pore arrays of size ranging from 66 to 90 Å as demonstrated by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and physical adsorption techniques. A variety of organosilane density in the range of 0.5-2.6 mmol/g was achieved as revealed by elemental analysis and solid-state nuclear magnetic resonance (NMR) techniques. The functionalized materials displayed improved properties for immobilization of penicillin acylase (PA) in comparison with pure-silica SBA-15. Such improvement is believed to be due to the enhanced surface hydrophobicity and electrostatic interactions of the functional groups with the enzyme.

  9. Nanoscale Bioengineering Solutions for Space Exploration the Nanopore Sequencer

    NASA Technical Reports Server (NTRS)

    Ioana, Cozmuta; Viktor, Stoic

    2005-01-01

    Characterization of biological systems at the molecular level and extraction of essential information for nano-engineering design to guide the nano-fabrication of solid-state sensors and molecular identification devices is a computational challenge. The alpha hemolysin protein ion channel is used as a model system for structural analysis of nucleic acids like DNA. Applied voltage draws a DNA strand and surrounding ionic solution through the biological nanopore. The subunits in the DNA strand block ion flow by differing amounts. Atomistic scale simulations are employed using NASA supercomputers to study DNA translocation. with the aim to enhance single DNA subunit identification. Compared to protein channels, solid-state nanopores offer a better temporal control of the translocation of DNA and the possibility to easily tune its chemistry to increase the signal resolution. Potential applications for NASA missions, besides real-time genome sequencing include astronaut health, life detection and decoding of various genomes. http://phenomrph.arc.nasa.gov/index.php

  10. Block copolymers confined in a nanopore: Pathfinding in a curving and frustrating flatland

    NASA Astrophysics Data System (ADS)

    Sevink, G. J. A.; Zvelindovsky, A. V.

    2008-02-01

    We have studied structure formation in a confined block copolymer melt by means of dynamic density functional theory. The confinement is two dimensional, and the confined geometry is that of a cylindrical nanopore. Although the results of this study are general, our coarse-grained molecular model is inspired by an experimental lamella-forming polysterene-polybutadiene diblock copolymer system [K. Shin et al., Science 306, 76 (2004)], in which an exotic toroidal structure was observed upon confinement in alumina nanopores. Our computational study shows that a zoo of exotic structures can be formed, although the majority, including the catenoid, helix, and double helix that were also found in Monte Carlo nanopore studies, are metastable states. We introduce a general classification scheme and consider the role of kinetics and elongational pressure on stability and formation pathway of both equilibrium and metastable structures in detail. We find that helicity and threefold connections mediate structural transitions on a larger scale. Moreover, by matching the remaining parameter in our mesoscopic method, the Flory-Huggins parameter χ, to the experimental system, we obtain a structure that resembles the experimental toroidal structure in great detail. Here, the most important factor seems to be the roughness of the pore, i.e., small variations of the pore radius on a scale that is larger than the characteristic size in the system.

  11. Schottky Barriers Based on Nanoporous InP with Gold Nanoparticles

    NASA Astrophysics Data System (ADS)

    Barlas, Tetyana; Dmitruk, Mykola; Kotova, Nataliya; Mamykin, Sergii

    2016-04-01

    Schottky barrier structures based on nanoporous InP with inclusion of Au nanoparticles and evaporated semitransparent Au film have been made. The spectra of short-circuit photocurrent in the visible range and current-voltage characteristics have been measured. Prepared structures are characterized by increased photocurrent due to the microrelief interface and surface plasmon excitation in gold nanoparticles as well as increased surface recombination especially in the short wavelength region.

  12. Schottky Barriers Based on Nanoporous InP with Gold Nanoparticles.

    PubMed

    Barlas, Tetyana; Dmitruk, Mykola; Kotova, Nataliya; Mamykin, Sergii

    2016-12-01

    Schottky barrier structures based on nanoporous InP with inclusion of Au nanoparticles and evaporated semitransparent Au film have been made. The spectra of short-circuit photocurrent in the visible range and current-voltage characteristics have been measured. Prepared structures are characterized by increased photocurrent due to the microrelief interface and surface plasmon excitation in gold nanoparticles as well as increased surface recombination especially in the short wavelength region. PMID:27075341

  13. Electron beam-assisted healing of nanopores in magnesium alloys

    PubMed Central

    Zheng, He; Liu, Yu; Cao, Fan; Wu, Shujing; Jia, Shuangfeng; Cao, Ajing; Zhao, Dongshan; Wang, Jianbo

    2013-01-01

    Nanopore-based sensing has emerged as a promising candidate for affordable and powerful DNA sequencing technologies. Herein, we demonstrate that nanopores can be successfully fabricated in Mg alloys via focused electron beam (e-beam) technology. Employing in situ high-resolution transmission electron microscopy techniques, we obtained unambiguous evidence that layer-by-layer growth of atomic planes at the nanopore periphery occurs when the e-beam is spread out, leading to the shrinkage and eventual disappearance of nanopores. The proposed healing process was attributed to the e-beam-induced anisotropic diffusion of Mg atoms in the vicinity of nanopore edges. A plausible diffusion mechanism that describes the observed phenomena is discussed. Our results constitute the first experimental investigation of nanopores in Mg alloys. Direct evidence of the healing process has advanced our fundamental understanding of surface science, which is of great practical importance for many technological applications, including thin film deposition and surface nanopatterning. PMID:23719630

  14. Controlled formation of closed-edge nanopores in graphene.

    PubMed

    He, Kuang; Robertson, Alex W; Gong, Chuncheng; Allen, Christopher S; Xu, Qiang; Zandbergen, Henny; Grossman, Jeffrey C; Kirkland, Angus I; Warner, Jamie H

    2015-07-21

    Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport. PMID:26088477

  15. Electron beam-assisted healing of nanopores in magnesium alloys

    NASA Astrophysics Data System (ADS)

    Zheng, He; Liu, Yu; Cao, Fan; Wu, Shujing; Jia, Shuangfeng; Cao, Ajing; Zhao, Dongshan; Wang, Jianbo

    2013-05-01

    Nanopore-based sensing has emerged as a promising candidate for affordable and powerful DNA sequencing technologies. Herein, we demonstrate that nanopores can be successfully fabricated in Mg alloys via focused electron beam (e-beam) technology. Employing in situ high-resolution transmission electron microscopy techniques, we obtained unambiguous evidence that layer-by-layer growth of atomic planes at the nanopore periphery occurs when the e-beam is spread out, leading to the shrinkage and eventual disappearance of nanopores. The proposed healing process was attributed to the e-beam-induced anisotropic diffusion of Mg atoms in the vicinity of nanopore edges. A plausible diffusion mechanism that describes the observed phenomena is discussed. Our results constitute the first experimental investigation of nanopores in Mg alloys. Direct evidence of the healing process has advanced our fundamental understanding of surface science, which is of great practical importance for many technological applications, including thin film deposition and surface nanopatterning.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

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

    PubMed

    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. PMID:27040079

  18. Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation

    PubMed Central

    Balme, Sébastien; Picaud, Fabien; Manghi, Manoel; Palmeri, John; Bechelany, Mikhael; Cabello-Aguilar, Simon; Abou-Chaaya, Adib; Miele, Philippe; Balanzat, Emmanuel; Janot, Jean Marc

    2015-01-01

    Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ionic transport through single putatively neutral hydrophobic nanopores with high aspect ratio (of length L = 6 μm with diameters ranging from 1 to 10 nm) and with a well controlled cylindrical geometry. We develop a detailed hybrid mesoscopic theoretical approach for the electrolyte conductivity inside nanopores, which considers explicitly ion advection by electro-osmotic flow and possible flow slip at the pore surface. By fitting the experimental conductance data we show that for nanopore diameters greater than 4 nm a constant weak surface charge density of about 10−2 C m−2 needs to be incorporated in the model to account for conductance plateaus of a few pico-siemens at low salt concentrations. For tighter nanopores, our analysis leads to a higher surface charge density, which can be attributed to a modification of ion solvation structure close to the pore surface, as observed in the molecular dynamics simulations we performed. PMID:26036687

  19. Integrating nanopore sensors within microfluidic channel arrays using controlled breakdown.

    PubMed

    Tahvildari, Radin; Beamish, Eric; Tabard-Cossa, Vincent; Godin, Michel

    2015-03-21

    Nanopore arrays are fabricated by controlled dielectric breakdown (CBD) in solid-state membranes integrated within polydimethylsiloxane (PDMS) microfluidic devices. This technique enables the scalable production of independently addressable nanopores. By confining the electric field within the microfluidic architecture, nanopore fabrication is precisely localized and electrical noise is significantly reduced. Both DNA and protein molecules are detected to validate the performance of this sensing platform. PMID:25631885

  20. Energy level transitions of gas in a 2D nanopore

    SciTech Connect

    Grinyaev, Yurii V.; Chertova, Nadezhda V.; Psakhie, Sergei G.

    2015-10-27

    An analytical study of gas behavior in a 2D nanopore was performed. It is shown that the temperature dependence of gas energy can be stepwise due to transitions from one size-quantized subband to another. Taking into account quantum size effects results in energy level transitions governed by the nanopore size, temperature and gas density. This effect leads to an abrupt change of gas heat capacity in the nanopore at the above varying system parameters.

  1. Study of polymer molecules and conformations with a nanopore

    DOEpatents

    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.

  2. Study of polymer molecules and conformations with a nanopore

    DOEpatents

    Golovchenko, Jene A; Li, Jiali; Stein, Derek; Gershow, Marc H

    2015-03-03

    The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

  3. Study of polymer molecules and conformations with a nanopore

    DOEpatents

    Golovchenko, Jene A.; Li, Jiali; Stein, Derek; Gershow, Marc H.

    2013-03-12

    The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

  4. Controlled formation of closed-edge nanopores in graphene

    NASA Astrophysics Data System (ADS)

    He, Kuang; Robertson, Alex W.; Gong, Chuncheng; Allen, Christopher S.; Xu, Qiang; Zandbergen, Henny; Grossman, Jeffrey C.; Kirkland, Angus I.; Warner, Jamie H.

    2015-07-01

    Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport.Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport. Electronic supplementary information (ESI) available: Low magnification images, image processing techniques employed, modelling and simulation of closed edge nanoribbon, comprehensive AC-TEM dataset, and supporting analysis. See DOI: 10.1039/c5nr02277k

  5. Catalytically solid-phase self-organization of nanoporous SnS with optical depolarizability.

    PubMed

    Cheng, Chih-Hsien; Chi, Yu-Chieh; Wu, Chung-Lun; Lin, Chun-Jung; Tsai, Ling-Hsuan; Chang, Jung-Hung; Chen, Mu Ku; Shih, Min-Hsiung; Lee, Chao-Kuei; Wu, Chih-I; Tsai, Din Ping; Lin, Gong-Ru

    2016-02-28

    The catalytic solid-phase synthesis of self-organized nanoporous tin sulfide (SnS) with enhanced absorption, manipulative transmittance and depolarization features is demonstrated. Using an ultralow radio-frequency (RF) sputtering power, the variation of the orientation angle between the anodized aluminum oxide (AAO) membrane and the axis of the sputtered ion beam detunes the catalytically synthesized SnS from nanorod to nanoporous morphology, along the sidewall of the AAO membrane. The ultraslow catalytic sputtering synthesis on the AAO at the RF plasma power of 20 W and the orientation angle of 0° regulates the porosity and integrality of nanoporous SnS, with average pore diameter of 80-150 nm. When transferring from planar to nanoporous structure, the phase composition changes from SnS to SnS2-Sn2S3, and the optical bandgap shrinks from 1.43 to 1.16 eV, due to the preferred crystalline orientation, which also contributes to an ultralow reflectance of <1% at 200-500 nm when both the transmittance and the surface scattering remain at their maxima. The absorption coefficient is enhanced by nearly one order of magnitude with its minimum of >5 × 10(4) cm(-1) at the wavelength between 200 and 700 nm, due to the red-shifting of the absorption spectrum to at least 100 nm. The catalytically self-organized nanoporous SnS causes strong haze and beam divergence of 20°-30° by depolarized nonlinear scattering at the surface, which favors the solar energy conversion with reduced surface reflection and enhanced photon scattering under preserved transmittance. PMID:26842460

  6. Observation and analysis of the Coulter effect through carbon nanotube and graphene nanopores.

    PubMed

    Agrawal, Kumar Varoon; Drahushuk, Lee W; Strano, Michael S

    2016-02-13

    Carbon nanotubes (CNTs) and graphene are the rolled and flat analogues of graphitic carbon, respectively, with hexagonal crystalline lattices, and show exceptional molecular transport properties. The empirical study of a single isolated nanopore requires, as evidence, the observation of stochastic, telegraphic noise from a blocking molecule commensurate in size with the pore. This standard is used ubiquitously in patch clamp studies of single, isolated biological ion channels and a wide range of inorganic, synthetic nanopores. In this work, we show that observation and study of stochastic fluctuations for carbon nanopores, both CNTs and graphene-based, enable precision characterization of pore properties that is otherwise unattainable. In the case of voltage clamp measurements of long (0.5-1 mm) CNTs between 0.9 and 2.2 nm in diameter, Coulter blocking of cationic species reveals the complex structuring of the fluid phase for confined water in this diameter range. In the case of graphene, we have pioneered the study and the analysis of stochastic fluctuations in gas transport from a pressurized, graphene-covered micro-well compartment that reveal switching between different values of the membrane permeance attributed to chemical rearrangements of individual graphene pores. This analysis remains the only way to study such single isolated graphene nanopores under these realistic transport conditions of pore rearrangements, in keeping with the thesis of this work. In summary, observation and analysis of Coulter blocking or stochastic fluctuations of permeating flux is an invaluable tool to understand graphene and graphitic nanopores including CNTs. PMID:26712649

  7. Catalytically solid-phase self-organization of nanoporous SnS with optical depolarizability

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Hsien; Chi, Yu-Chieh; Wu, Chung-Lun; Lin, Chun-Jung; Tsai, Ling-Hsuan; Chang, Jung-Hung; Chen, Mu Ku; Shih, Min-Hsiung; Lee, Chao-Kuei; Wu, Chih-I.; Tsai, Din Ping; Lin, Gong-Ru

    2016-02-01

    The catalytic solid-phase synthesis of self-organized nanoporous tin sulfide (SnS) with enhanced absorption, manipulative transmittance and depolarization features is demonstrated. Using an ultralow radio-frequency (RF) sputtering power, the variation of the orientation angle between the anodized aluminum oxide (AAO) membrane and the axis of the sputtered ion beam detunes the catalytically synthesized SnS from nanorod to nanoporous morphology, along the sidewall of the AAO membrane. The ultraslow catalytic sputtering synthesis on the AAO at the RF plasma power of 20 W and the orientation angle of 0° regulates the porosity and integrality of nanoporous SnS, with average pore diameter of 80-150 nm. When transferring from planar to nanoporous structure, the phase composition changes from SnS to SnS2-Sn2S3, and the optical bandgap shrinks from 1.43 to 1.16 eV, due to the preferred crystalline orientation, which also contributes to an ultralow reflectance of <1% at 200-500 nm when both the transmittance and the surface scattering remain at their maxima. The absorption coefficient is enhanced by nearly one order of magnitude with its minimum of >5 × 104 cm-1 at the wavelength between 200 and 700 nm, due to the red-shifting of the absorption spectrum to at least 100 nm. The catalytically self-organized nanoporous SnS causes strong haze and beam divergence of 20°-30° by depolarized nonlinear scattering at the surface, which favors the solar energy conversion with reduced surface reflection and enhanced photon scattering under preserved transmittance.

  8. DNA translocation through single-layer boron nitride nanopores.

    PubMed

    Gu, Zonglin; Zhang, Yuanzhao; Luan, Binquan; Zhou, Ruhong

    2016-01-21

    Ultra-thin nanopores have become promising biological sensors because of their outstanding signal-to-noise ratio and spatial resolution. Here, we show that boron nitride (BN), which is a new two-dimensional (2D) material similar to graphene, could be utilized for making a nanopore with an atomic thickness. Using an all-atom molecular dynamics simulation, we investigated the dynamics of DNA translocation through the BN nanopore. The results of our simulations demonstrated that it is possible to detect different double-stranded DNA (dsDNA) sequences from the recording of ionic currents through the pore during the DNA translocation. Surprisingly, opposite to results for a graphene nanopore, we found the calculated blockage current for poly(A-T)40 in a BN nanopore to be less than that for poly(G-C)40. Also in contrast with the case of graphene nanopores, dsDNA models moved smoothly and in an unimpeded manner through the BN nanopores in the simulations, suggesting a potential advantage for using BN nanopores to design stall-free sequencing devices. BN nanopores, which display several properties (such as being hydrophilic and non-metallic) that are superior to those of graphene, are thus expected to find applications in the next generation of high-speed and low-cost biological sensors. PMID:26537824

  9. DNA damage due to perfluorooctane sulfonate based on nano-gold embedded in nano-porous poly-pyrrole film

    NASA Astrophysics Data System (ADS)

    Lu, Liping; Xu, Laihui; Kang, Tianfang; Cheng, Shuiyuan

    2013-11-01

    DNA damage induced from perfluorooctane sulfonate (PFOS) was further developed on a nano-porous bionic interface. The interface was formed by assembling DNA on nano-gold particles which were embedded in a nano-porous overoxidized polypyrrole film (OPPy). Atomic force microscopy, scanning electron microscope and electrochemical investigations indicate that OPPy can be treated to form nano-pore structures. DNA damage due to PFOS was proved using electrochemistry and X-ray photoelectron spectroscopy (XPS) and was investigated by detecting differential pulse voltammetry (DPV) response of methylene blue (MB) which was used as electro-active indicator in the system. The current of MB attenuates obviously after incubation of DNA in PFOS. Moreover, electrochemical impedance spectroscopy (EIS) demonstrates that PFOS weakens DNA charge transport. The tentative binding ratio of PFOS: DNA base pair was obtained by analyzing XPS data of this system.

  10. Dealloying-driven nanoporous palladium with superior electrochemical actuation performance

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Bai, Qingguo; Zhang, Zhonghua

    2016-03-01

    Metal-hydrogen (in particular, Pd-H) interactions have been receiving considerable attention over the past 150 years within the scope of hydrogen storage, catalytic hydrogenation, hydrogen embrittlement and hydrogen-induced interfacial failure. Here, for the first time, we show that the coupling of hydrogen adsorption and absorption could trigger giant reversible strain in bulk nanoporous Pd (np-Pd) in a weakly adsorbed NaF electrolyte. The bulk np-Pd with a hierarchically porous structure and a ligament/channel size of ~10 nm was fabricated using a dealloying strategy with compositional/structural design of the precursor. The np-Pd actuator exhibits a giant reversible strain of up to 3.28% (stroke of 137.8 μm), which is a 252% enhancement in comparison to the state-of-the-art value of 1.3% in np-AuPt. The strain rate (~10-5 s-1) of np-Pd is two orders of magnitude higher than that of current metallic actuators. Moreover, the volume-/mass-specific strain energy density (10.71 MJ m-3/3811 J kg-1) of np-Pd reaches the highest level compared with that of previously reported actuator materials. The outstanding actuation performance of np-Pd could be attributed to the coupling of hydrogen adsorption/absorption and its unique hierarchically nanoporous structure. Our findings provide valuable information for the design of novel high-performance metallic actuators.Metal-hydrogen (in particular, Pd-H) interactions have been receiving considerable attention over the past 150 years within the scope of hydrogen storage, catalytic hydrogenation, hydrogen embrittlement and hydrogen-induced interfacial failure. Here, for the first time, we show that the coupling of hydrogen adsorption and absorption could trigger giant reversible strain in bulk nanoporous Pd (np-Pd) in a weakly adsorbed NaF electrolyte. The bulk np-Pd with a hierarchically porous structure and a ligament/channel size of ~10 nm was fabricated using a dealloying strategy with compositional/structural design of the

  11. Fast-response humidity-sensing films based on methylene blue aggregates formed on nanoporous semiconductor films

    NASA Astrophysics Data System (ADS)

    Ishizaki, Ryota; Katoh, Ryuzi

    2016-05-01

    We prepared fast-response colorimetric humidity-sensing (vapochromic) films based on methylene blue adsorption onto nanoporous semiconductor (TiO2, Al2O3) films. Color changes caused by changes of humidity could be easily identified visually. A characteristic feature of the vapochromic films was their fast response to changes of humidity. We found that the response began to occur within 10 ms. The response was rapid because all the methylene blue molecules attached to the nanoporous semiconductor surface were directly exposed to the environment. We also deduced that the color changes were caused by structural changes of the methylene blue aggregates on the surface.

  12. Asymmetric plasmonic induced ionic noise in metallic nanopores

    NASA Astrophysics Data System (ADS)

    Li, Yi; Chen, Chang; Willems, Kherim; Lagae, Liesbet; Groeseneken, Guido; Stakenborg, Tim; van Dorpe, Pol

    2016-06-01

    We present distinct asymmetric plasmon-induced noise properties of ionic transport observed through gold coated nanopores. We thoroughly investigated the effects of bias voltage and laser illumination. We show that the potential drop across top-coated silicon nanocavity pores can give rise to a large noise asymmetry (~2-3 orders of magnitude). Varying the bias voltage has an appreciable effect on the noise density spectra, typically in the Lorentzian components. The laser power is found to strongly affect the ionic noise level as well as the voltage threshold for light-induced noise generation. The asymmetric noise phenomenon is attributed to plasmon-induced interfacial reactions which promote light-induced charge fluctuation in the ion flow and allow voltage modulation of photo-induced carriers surmounting over such Schottky junctions. We further compare the ionic noise performances of gold nanocavities containing different material stacks, among which thermal oxide passivation of the silicon successfully mitigates the light-induced noise and is also fully CMOS-compatible. The understanding of the described noise characteristics will help to foster multiple applications using related structures including plasmonic-based sensing or plasmon-induced catalysis such as water splitting or solar energy conversion devices.We present distinct asymmetric plasmon-induced noise properties of ionic transport observed through gold coated nanopores. We thoroughly investigated the effects of bias voltage and laser illumination. We show that the potential drop across top-coated silicon nanocavity pores can give rise to a large noise asymmetry (~2-3 orders of magnitude). Varying the bias voltage has an appreciable effect on the noise density spectra, typically in the Lorentzian components. The laser power is found to strongly affect the ionic noise level as well as the voltage threshold for light-induced noise generation. The asymmetric noise phenomenon is attributed to plasmon

  13. Nanoporous Cathodes for High-Energy Li-S Batteries from Gyroid Block Copolymer Templates.

    PubMed

    Choudhury, Soumyadip; Agrawal, Mukesh; Formanek, Petr; Jehnichen, Dieter; Fischer, Dieter; Krause, Beate; Albrecht, Victoria; Stamm, Manfred; Ionov, Leonid

    2015-06-23

    This study reports on a facile approach to the fabrication of nanoporous carbon cathodes for lithium sulfur batteries using gyroid carbon replicas based on use of polystyrene-poly-4-vinylpyridine (PS-P4VP) block copolymers as sacrificial templates. The free-standing gyroid carbon network with a highly ordered and interconnected porous structure has been fabricated by impregnating the carbon precursor solution into the gyroid block copolymer nanotemplates and subsequently carbonizing them. A wide range of analytical tools have been employed to characterize fabricated porous carbon material. Prepared nanostructures are envisioned to have a great potential in myriad areas such as energy storage/conversion devices owing to their fascinating morphology exhibiting high surface area and uniform porosity with interconnected three-dimensional networks. The resulting carbon nanoporous structures infused with elemental sulfur have been found to work as a promising electrode for lithium sulfur batteries demonstrating a high cycling stability over more than 200 cycles. PMID:26014100

  14. Parameter modeling for nanopore lonic field effect transistors in 3-D device simulation.

    PubMed

    Park, Jun-Mo; Chun, Honggu; Park, Y Eugene; Park, Byung-Gook; Lee, Jong-Ho

    2014-11-01

    An Ion Field Effect Transistor (IFET) with nanopore structure was modeled in a conventional 3-dimensional (3-D) device simulator to understand current-voltage (I-V) characteristics and underlying physics of the device. Since the nanopore was filled with positive ions (K+) ions due to the negative interface charge on the insulator surface and negative gate bias condition, we could successfully simulate the IFET structure using modified p-type silicon to mimic KCl solution. We used p-type silicon with a doping concentration of 6.022 x 10(16) cm(-3) which has the same concentration of positive carriers (hole) as in 10(-4) M KCl. By controlling gate electric field effect on the mobility, the I-V curves obtained by the parameter modeling matched very well with the measured data. In addition, the decrease of [V(th)] with increasing V(DS) was physically analyzed. PMID:25958494

  15. Ordered arrays of nanoporous silicon nanopillars and silicon nanopillars with nanoporous shells

    PubMed Central

    2013-01-01

    The fabrication of ordered arrays of nanoporous Si nanopillars with and without nanoporous base and ordered arrays of Si nanopillars with nanoporous shells are presented. The fabrication route is using a combination of substrate conformal imprint lithography and metal-assisted chemical etching. The metal-assisted chemical etching is performed in solutions with different [HF]/[H2O2 + HF] ratios. Both pore formation and polishing (marked by the vertical etching of the nanopillars) are observed in highly doped and lightly doped Si during metal-assisted chemical etching. Pore formation is more active in the highly doped Si, while the transition from polishing to pore formation is more obvious in the lightly doped Si. The etching rate is clearly higher in the highly doped Si. Oxidation occurs on the sidewalls of the pillars by etching in solutions with small [HF]/[H2O2 + HF] ratios, leading to thinning, bending, and bonding of pillars. PMID:23336430

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

    PubMed

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

    2016-04-14

    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. PMID:27020686

  17. Ion fluxes through nanopores and transmembrane channels

    NASA Astrophysics Data System (ADS)

    Bordin, J. R.; Diehl, A.; Barbosa, M. C.; Levin, Y.

    2012-03-01

    We introduce an implicit solvent Molecular Dynamics approach for calculating ionic fluxes through narrow nanopores and transmembrane channels. The method relies on a dual-control-volume grand-canonical molecular dynamics (DCV-GCMD) simulation and the analytical solution for the electrostatic potential inside a cylindrical nanopore recently obtained by Levin [Europhys. Lett.EULEEJ0295-507510.1209/epl/i2006-10240-4 76, 163 (2006)]. The theory is used to calculate the ionic fluxes through an artificial transmembrane channel which mimics the antibacterial gramicidin A channel. Both current-voltage and current-concentration relations are calculated under various experimental conditions. We show that our results are comparable to the characteristics associated to the gramicidin A pore, especially the existence of two binding sites inside the pore and the observed saturation in the current-concentration profiles.

  18. Surface chemistry driven actuation in nanoporous gold

    SciTech Connect

    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.

  19. High Density Methane Storage in Nanoporous Carbon

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  20. Ordered arrays of patterned nanoporous silicon

    NASA Astrophysics Data System (ADS)

    Wang, D.; Schönherr, S.; Ji, R.; Herz, A.; Ronning, C.; Schaaf, P.

    2013-07-01

    The fabrication of ordered arrays of patterned nanoporous Si with two-level nanostructures using a combination of metal-assisted chemical etching and nanoimprint lithography is presented. One nanostructure is the periodic arrays of holes and pillars with a period of several hundred nanometers and another nanostructure is the nanoporosity with a pore size of about 10 nm. The etching rate of (1 0 0) oriented Si is clearly higher than that of (1 1 0) and (1 1 1) oriented Si under the same conditions. More effective pore formation occurs in (1 1 1) oriented Si than in (1 0 0) and (1 1 0) oriented Si. Cathodoluminescence was measured and the patterned array of nanoporous Si shows visible luminescence with an overlap of two red emission bands at room temperature.

  1. A universal model for nanoporous carbon supercapacitors

    SciTech Connect

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

    2009-01-01

    Supercapacitors based on nanoporous carbon materials, 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. Nanoporous carbon supercapacitors are generally viewed as a parallel-plate capacitor since supercapacitors store energy by charge separation in an electric double layer formed at the electrode/electrolyte interface. The EDLC model has been used to characterize the energy storage of supercapacitors for decades. We comment in this chapter on the shortcomings of the EDLC model when applied to nanoporous carbon supercapacitors. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we have proposed a heuristic model that takes pore curvature into account as a replacement for the EDLC model. When the pore size is in the mesopore regime (2 50 nm), electrolyte counterions enter mesoporous carbons and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (< 2 nm), solvated/desolvated counterions line up along the pore axis to form an electric wire-in-cylinder capacitor (EWCC). In the macropore regime (> 50 nm), where pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced to the EDLC model. With the backing of experimental data and quantum density functional theory calculations, we have shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials and electrolytes. The strengths and limitations of this new model are discussed. The new model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration, dielectric constant, and solute ion size, and may lend support to the systematic optimization of the properties of carbon supercapacitors through experiments.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Tuneable graphene nanopores for single biomolecule detection.

    PubMed

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

    2016-05-21

    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. PMID:27171594

  4. The Potential and Challenges of Nanopore Sequencing

    SciTech Connect

    Branton, Daniel; Deamer, D. W.; Marziali, A.; Bayley, H.; Benner, S. A.; Butler, Thomas; Di Ventra, Massimiliano; Garaj, S.; Hibbs, Andrew; Huang, Xiaohua; Jovanovich, Stevan B.; Krstic, Predrag S; Lindsay, Stuart; Ling, Xinsheng Sean; Mastrangelo, Carlos H.; Meller, Amit; Oliver, John S.; Pershin, Yuriy V.; Ramsey, Dr. John Michael; Riehn, Robert; Soni, Gautam; Tabard-Cossa, Vincent; Wanuunu, Meni; Wiggin, Matthew; Schloss, Jeffrey A

    2008-10-01

    A nanopore-based device provides single-molecule detection and analytical capabilities that are achieved by electrophoretically driving molecules in solution through a nan-scale pore. The nanopore provides a highly confined space within which single nucleic acid polymers can be analyzed at high throughput by one of a variety of means, and the perfect processivity that can be enforced in a narrow pore ensures that the native order of the nucleobases in a polynucleotide is reflected in the sequence of signals that is detected. Kilobase length polymers (single-stranded genomic DNA or RNA) or small molecules (e.g., nucleosides) can be identified and characterized without amplification or labeling, a unique analytical capability that makes inexpensive, rapid DNA sequencing a possibility. Further research and development to overcome current challenges to nanopore identification of each successive nucleotide in a DNA strand offers the prospect of 'third generation' instruments that will sequence a diploid mammalian genome for ~$1,000 in ~24 h.

  5. Nanoporous Materials from ABAC Tetrablock Terpolymers

    NASA Astrophysics Data System (ADS)

    Jackson, Elizabeth Ashley

    This dissertation describes efforts towards the preparation of tough nanoporous membranes from ABAC tetrablock terpolymers. This architecture was strategically chosen to combine an etchable C block, PLA, with a mechanically tough ABA triblock into one ABAC terpolymer. Multiple series of poly(styrene- b-isoprene-b-styrene-b-lactide) (PS-PI-PS-PLA) tetrablock terpolymers were synthesized. Morphological behavior was characterized for terpolymers containing both a 50:50 and 30:70 PS:PI ratio with between 0 and ~20% PLA by volume. Observed bulk morphologies include hexagonally packed cylinders (HEX), core(PLA)-shell(PS) cylinders (CSC), and a PLA sphere in cylinder morphology. Mechanical properties of PS-PEEP-PS-PLA tetrablocks were also investigated. All materials exhibited mechanical properties characteristic of tough thermoplastic elastomers. Composite membranes were prepared from a thin film of PS-PI-PS-PLA terpolymer and a macroporous polyethersulfone support. Described within are the efforts related to the fabrication and filtration performance of these nanoporous PS-PI-PS composite membranes. As part of this process, solvent casting and annealing conditions were varied to investigate effects on tetrablock thin film morphology. Optimum conditions were determined to achieve PS-PI-PS-PLA films with perpendicular PLA cylinder orientation. These conditions included use of a mixed solvent system and the addition of a small amount of homopolymer PLA. Highly ordered films with vertically oriented nanopores were obtained.

  6. Direct single ion machining of nanopores.

    SciTech Connect

    Doyle, Barney Lee; Follstaedt, David Martin; Rossi, Paolo; Norman, Adam K.

    2004-10-01

    The irradiation of thin insulating films by high-energy ions (374 MeV Au{sup +25} or 241 MeV I{sup +19}) was used to attempt to form nanometer-size pores through the films spontaneously. Such ions deposit a large amount of energy into the target materials ({approx}20 keV/nm), which significantly disrupts their atomic lattice and sputters material from the surfaces, and might produce nanopores for appropriate ion-material combinations. Transmission electron microscopy was used to examine the resulting ion tracks. Tracks were found in the crystalline oxides quartz, sapphire, and mica. Sapphire and mica showed ion tracks that are likely amorphous and exhibit pits 5 nm in diameter on the surface at the ion entrance and exit points. This suggests that nanopores might form in mica if the film thickness is less than {approx}10 nm. Tracks in quartz showed strain in the matrix around them. Tracks were not found in the amorphous thin films examined: 20 nm-SiN{sub x}, deposited SiOx, fused quartz (amorphous SiO{sub 2}), formvar and 3 nm-C. Other promising materials for nanopore formation were identified, including thin Au and SnO{sub 2} layers.

  7. Tuneable graphene nanopores for single biomolecule detection

    NASA Astrophysics Data System (ADS)

    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. Scale effects in the latent heat of melting in nanopores.

    PubMed

    Shin, J-H; Parlange, J-Y; Deinert, M R

    2013-07-28

    The curvature of a liquid vapor interface has long been known to change the equilibrium vapor pressure. It has also been shown that a capillary structure will affect the temperature at which both freezing and vaporization of a substance will occur. However, describing interfacial effects on the latent heat of a phase change has proven more difficult. Here, we present a classical thermodynamic model for how the latent heat of melting changes as the size of the particles undergoing the transition decreases. The scale dependence for the surface tension is taken into consideration using a Tolman length correction. The resulting model is tested by fitting to published experimental data for the latent heat of melting for benzene, heptane, naphthalene, and water contained in nano-porous glass. In all cases the model fits the data with a R(2) ≥ 0.94. PMID:23901997

  9. A Simple Route for Preparation of Nanoporous Templates

    NASA Astrophysics Data System (ADS)

    Park, Soojin; Wang, Jia-Yu; Kim, Bokyung; Russell, Thomas

    2007-03-01

    Spin-coating method of block copolymers represents a very simple means of producing thin films for the fabrication of nanostructured materials. However, the orientation and long-range ordering of the block copolymer microdomains must be controlled to maximize areal density. Here, spin coated films of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymers in THF/toluene solvent mixtures were investigated and it was found that highly oriented cylindrical microdomains with long-range lateral order were obtained on a variety of substrates, such as silicon oxide, polystyrene, polyimide, poly(butylene terephthalate), and germanium. The preferential solvation of P4VP block with an alcohol enabled a surface reconstruction to produce a structure of the block copolymer film that leads to the generation of a nanoporous template upon drying. The gold evaporation on the reconstructed films produces thermally stable and plasma resistant films.

  10. Lithium atom storage in nanoporous cellulose via surface-induced Li2 breakage

    NASA Astrophysics Data System (ADS)

    Boström, Mathias; Huang, Dan; Yang, Weihong; Persson, Clas; Sernelius, Bo E.

    2013-12-01

    We demonstrate a physical mechanism that enhances a splitting of diatomic Li2 at cellulose surfaces. The origin of this splitting is a possible surface-induced diatomic-excited-state resonance repulsion. The atomic Li is then free to form either physical or chemical bonds with the cellulose surface and even diffuse into the cellulose layer structure. This allows for an enhanced storage capacity of atomic Li in nanoporous cellulose.

  11. Ultraselective Gas Separation by Nanoporous Metal-Organic Frameworks Embedded in Gas-Barrier Nanocellulose Films.

    PubMed

    Matsumoto, Makoto; Kitaoka, Takuya

    2016-03-01

    Metal-organic frameworks (MOFs) are synthesized at carboxy groups on crystalline TEMPO-oxidized cellulose nanofibers (TOCNs). MOF-TOCN films coated on a paper filter have a hierarchical structure from the nano- to macroscale, and demonstrate a high CO2 /CH4 selectivity, over 120 for CO2 at a high gas flux, by the combination of the nanoporous MOFs and the gas-barrier TOCNs, which have strong affinity with each other. PMID:26669724

  12. Nanoporous anodic titanium dioxide layers as potential drug delivery systems: Drug release kinetics and mechanism.

    PubMed

    Jarosz, Magdalena; Pawlik, Anna; Szuwarzyński, Michał; Jaskuła, Marian; Sulka, Grzegorz D

    2016-07-01

    Nanoporous anodic titanium dioxide (ATO) layers on Ti foil were prepared via a three step anodization process in an electrolyte based on an ethylene glycol solution with fluoride ions. Some of the ATO samples were heat-treated in order to achieve two different crystallographic structures - anatase (400°C) and a mixture of anatase and rutile (600°C). The structural and morphological characterizations of ATO layers were performed using a field emission scanning electron microscope (SEM). The hydrophilicity of ATO layers was determined with contact angle measurements using distilled water. Ibuprofen and gentamicin were loaded effectively inside the ATO nanopores. Afterwards, an in vitro drug release was conducted for 24h under a static and dynamic flow conditions in a phosphate buffer solution at 37°C. The drug concentrations were determined using UV-Vis spectrophotometry. The absorbance of ibuprofen was measured directly at 222nm, whether gentamicin was determined as a complex with silver nanoparticles (Ag NPs) at 394nm. Both compounds exhibited long term release profiles, despite the ATO structure. A new release model, based on the desorption of the drug from the ATO top surface followed by the desorption and diffusion of the drug from the nanopores, was derived. The proposed release model was fitted to the experimental drug release profiles, and kinetic parameters were calculated. PMID:27037782

  13. Silica nanoporous membranes and their applications

    NASA Astrophysics Data System (ADS)

    Khabibullin, Amir

    This thesis describes the development of novel silica and hybrid nanoporous membranes. Nanoporous membranes are widely used in various applications. This thesis focuses on their potential applications in the energy area, such as fuel cells and lithium batteries, and in separations and ultrafiltration. We use silica colloidal spheres and polymer-modified silica spheres to prepare the membranes in a time-, cost- and material-efficient manner. First, we prepared novel silica nanoporous membranes by pressing silica colloidal spheres followed by sintering. The pore size, the thickness, and the area of the membrane are precisely controlled by experiment parameters. The resulting membranes are mechanically and thermally durable, crack-free, and capable of size-selective transport. Next, to demonstrate the utility of the pressed membranes, described above, the proton-conductive pore-filled silica colloidal membranes were prepared and the fuel cells were constructed using these membranes. We modified these membranes by filling the membrane pores with surface-attached proton-conductive polymer brushes and prepared membrane-electrode assemblies to test fuel cell performance. We studied the proton conductivity and fuel cell performance as a function of the amount of sulfonic groups in the membrane. We also prepared and characterized reversible hybrid nanoporous membranes, self-assembled from solution containing polymer-modified silica colloidal spheres. Here we applied the new concept of noncovalent membranes, where the material is held together via noncovalent interactions of polymer brushes. This enables so-called reversible assembly of the membranes, in which membrane can be assembled in one solvent and dissolved in other. This approach provides advantages in recycling and reusing of the material. This work is one of the first of its kind and it opens a whole new area of research on reversible membranes made of polymer-modified nanoparticles. Finally, we applied our

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

    NASA Astrophysics Data System (ADS)

    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

  15. Active current gating in electrically biased conical nanopores

    NASA Astrophysics Data System (ADS)

    Bearden, Samuel; Simpanen, Erik; Zhang, Guigen

    2015-05-01

    We observed that the ionic current through a gold/silicon nitride (Si3N4) nanopore could be modulated and gated by electrically biasing the gold layer. Rather than employing chemical modification to alter device behavior, we achieved control of conductance directly by electrically biasing the gold portion of the nanopore. By stepping through a range of bias potentials under a constant trans-pore electric field, we observed a gating phenomenon in the trans-pore current response in a variety of solutions including potassium chloride (KCl), sodium chloride (NaCl), and potassium iodide (KI). A computational model with a conical nanopore was developed to examine the effect of the Gouy-Chapman-Stern electrical double layer along with nanopore geometry, work function potentials, and applied electrical bias on the ionic current. The numerical results indicated that the observed modulation and gating behavior was due to dynamic reorganization of the electrical double layer in response to changes in the electrical bias. Specifically, in the conducting state, the nanopore conductance (both numerical and experimental) is linearly proportional to the applied bias due to accumulation of charge in the diffuse layer. The gating effect occurs due to the asymmetric charge distribution in the fluid induced by the distribution of potentials at the nanopore surface. Time dependent changes in current due to restructuring of the electrical double layer occur when the electrostatic bias is instantaneously changed. The nanopore device demonstrates direct external control over nanopore behavior via modulation of the electrical double layer by electrostatic biasing.

  16. Single Nanoparticle Translocation Through Chemically Modified Solid Nanopore.

    PubMed

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

    2016-12-01

    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. PMID:26831688

  17. Catalytic pyrolysis of oilsand bitumen over nanoporous catalysts.

    PubMed

    Lee, See-Hoon; Heo, Hyeon Su; Jeong, Kwang-Eun; Yim, Jin-Heong; Jeon, Jong-Ki; Jung, Kyeong Youl; Ko, Young Soo; Kim, Seung-Soo; Park, Young-Kwon

    2011-01-01

    The catalytic cracking of oilsand bitumen was performed over nanoporous materials at atmospheric conditions. The yield of gas increased with application of nanoporous catalysts, with the catalytic conversion to gas highest for Meso-MFI. The cracking activity seemed to correlate with pore size rather than weak acidity or surface area. PMID:21446540

  18. Single Nanoparticle Translocation Through Chemically Modified Solid Nanopore

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  20. Nanopore analysis of amyloid fibrils formed by lysozyme aggregation.

    PubMed

    Martyushenko, Nikolay; Bell, Nicholas A W; Lamboll, Robin D; Keyser, Ulrich F

    2015-07-21

    The measurement of single particle size distributions of amyloid fibrils is crucial for determining mechanisms of growth and toxicity. Nanopore sensing is an attractive solution for this problem since it gives information on aggregates' shapes with relatively high throughput for a single particle technology. In this paper we study the translocation of lysozyme fibrils through quartz glass nanopores. We demonstrate that, under appropriate salt and pH conditions, lysozyme fibrils translocate through bare quartz nanopores without causing significant clogging. This enables us to measure statistics on tens of thousands of translocations of lysozyme fibrils with the same nanopore and track their development over a time course of aggregation spanning 24 h. Analysis of our events shows that the statistics are consistent with a simple bulk conductivity model for the passage of rods with a fixed cross sectional area through a conical glass nanopore. PMID:25994201

  1. Universal Scaling Law for the Collapse of Viscous Nanopores.

    PubMed

    Lu, Jiakai; Yu, Jiayun; Corvalan, Carlos M

    2015-08-11

    Below a threshold size, a small pore nucleated in a fluid sheet will contract to minimize the surface energy. Such behavior plays a key role in nature and technology, from nanopores in biological membranes to nanopores in sensors for rapid DNA and RNA sequencing. Here we show that nanopores nucleated in viscous fluid sheets collapse following a universal scaling law for the pore radius. High-fidelity numerical simulations reveal that the scaling is largely independent of the initial conditions, including the size, shape, and thickness of the original nanopore. Results further show that the scaling law yields a constant speed of collapse as observed in recent experiments. Nanopores in fluid sheets of moderate viscosity also attain this constant terminal speed provided that they are sufficiently close to the singularity. PMID:26230279

  2. Characterization of Nanoporous Materials with Atom Probe Tomography.

    PubMed

    Pfeiffer, Björn; Erichsen, Torben; Epler, Eike; Volkert, Cynthia A; Trompenaars, Piet; Nowak, Carsten

    2015-06-01

    A method to characterize open-cell nanoporous materials with atom probe tomography (APT) has been developed. For this, open-cell nanoporous gold with pore diameters of around 50 nm was used as a model system, and filled by electron beam-induced deposition (EBID) to obtain a compact material. Two different EBID precursors were successfully tested-dicobalt octacarbonyl [Co2(CO)8] and diiron nonacarbonyl [Fe2(CO)9]. Penetration and filling depth are sufficient for focused ion beam-based APT sample preparation. With this approach, stable APT analysis of the nanoporous material can be performed. Reconstruction reveals the composition of the deposited precursor and the nanoporous material, as well as chemical information of the interfaces between them. Thus, it is shown that, using an appropriate EBID process, local chemical information in three dimensions with sub-nanometer resolution can be obtained from nanoporous materials using APT. PMID:25990813

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

    NASA Astrophysics Data System (ADS)

    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.

  4. The role of nanopore shape in surface-induced crystallization

    NASA Astrophysics Data System (ADS)

    Diao, Ying; Harada, Takuya; Myerson, Allan S.; Alan Hatton, T.; Trout, Bernhardt L.

    2011-11-01

    Crystallization of a molecular liquid from solution often initiates at solid-liquid interfaces, and nucleation rates are generally believed to be enhanced by surface roughness. Here we show that, on a rough surface, the shape of surface nanopores can also alter nucleation kinetics. Using lithographic methods, we patterned polymer films with nanopores of various shapes and found that spherical nanopores 15-120 nm in diameter hindered nucleation of aspirin crystals, whereas angular nanopores of the same size promoted it. We also show that favourable surface-solute interactions are required for angular nanopores to promote nucleation, and propose that pore shape affects nucleation kinetics through the alteration of the orientational order of the crystallizing molecule near the angles of the pores. Our findings have clear technological implications, for instance in the control of pharmaceutical polymorphism and in the design of ‘seed’ particles for the regulation of crystallization of fine chemicals.

  5. Synthesis and Characterization of Nanoporous Alumina Films and their Application to Nanorod Array Fabrication

    NASA Astrophysics Data System (ADS)

    Abolhassani Monfared, Negar

    The purpose of this study is to synthesize and characterize the nanoporous structures that can be obtained by the anodization of thin film aluminum sputter deposited on a silicon wafer substrate. This study also investigated the application of nanoporous alumina to fabricate nanorod arrays by using preceramic polymers. Although there are many studies on the effect of anodizing conditions on anodized alumina, there are a few studies on anodizing of thin film aluminum. Anodized thin film of aluminum supported on silicon could have several applications that involve integrating the nanoporous structures into chemical and biological sensors and as templates for creating hierarchically complex nanostructures that are integrated with microelectronic circuits. In this study the different attributes of anodizing parameters in the synthesis of nanoporous structures on thin film aluminum compared to the results of studies on aluminum bulk is investigated. These differences can be due to attributes of the material, the resistance of the substrate and the reactions of substrate during anodizing. In this study the effects of different anodizing parameters and the contribution of each parameter were investigated using statistical approaches for quantification of pore sizes, their distributions and pore densities. This approach has never been previously used for studying the aluminum anodization. Until now, studies have always been based on average of the structure parameters with the hypothesis of homogeneity and uniformity of the structure which is not the case for anodization of thin film aluminum. To investigate the relative effect of each parameter, the Taguchi method and signal-to-noise calculation were applied. A new fabrication method for making nanorod arrays was introduced. In this method, nanoporous alumina was used as a casting mold for being filled by a preceramic polymer. KDT Ceraset polysilazane 20 (PSZ) and KDT Ceraset polyureasilazane (PUSZ) were two preceramic

  6. Molecular Sensing with Protein and Solid-State Nanopores

    NASA Astrophysics Data System (ADS)

    Niedzwiecki, David J.

    In the past 15 years nanopore sensing has proven to be a successful method for probing a variety of molecules of biological interest, such as DNA, RNA and proteins. Of particular appeal is this technique's ability to probe these molecules without the need for chemical modification or labeling, to do so at physiological conditions, and to probe single molecules at a time, allowing the possibility for results masked in bulk measurements to come to light. In this thesis these advantageous properties will be used in work on both a synthetic (solid-state) nanopore system and an engineered biological nanopore. I will describe the techniques for producing solid-state nanopores in thin membranes of silicon nitride and how these nanopores can be integrated into a fully functioning nanopore sensor system. I will then explore two applications of this system. First, a study of adsorption of bovine serum albumin (BSA), a protein found in blood serum, to the inorganic surface of nitride at the single molecule level. A simple physical model describing the behavior of this protein in the nanopore will be shown. Second, a study of the binding of the nucleocapsid protein of HIV-1 (NCp7) to three aptamers of different affinity, specifically three sequence 20mer mimics of the stem-loop 3 (SL3) RNA---the packaging domain of genomic RNA. Additionally, N-ethylmaleimide, which is known to inhibit the binding of NCp7 to a high-affinity SL3 RNA aptamer, will be used to demonstrate that the inhibition of the binding can be monitored in real time. Following these applications of the solid-state nanopore system, I will explore the geometry of a newly engineered biological nanopore, FhuA DeltaC/Delta4L, by using inert polymers to probe the nanopore interior.

  7. Chemically responsive nanoporous pigments: colorimetric sensor arrays and the identification of aliphatic amines.

    PubMed

    Bang, Jin Ho; Lim, Sung H; Park, Erwin; Suslick, Kenneth S

    2008-11-18

    A general method has been developed for the preparation of microspheres of nanoporous pigments, their formulation into chemically responsive pigment inks, and the printing of these inks as colorimetric sensor arrays. Using an ultrasonic-spray aerosol-gel synthesis from chemically responsive dyes and common silica precursors, 16 different nanoporous pigment microspheres have been prepared and characterized. New colorimetric sensor arrays have been created by printing inks of these chemically responsive pigments as primary sensor elements; these arrays have been successfully tested for the detection, identification, and quantitation of toxic aliphatic amines. Among 11 structurally similar amines, complete identification of each analyte without confusion was achieved using hierarchical cluster analysis (HCA). Furthermore, visual identification of ammonia gas was easily made at the IDLH (immediately dangerous to life or health), PEL (permissible exposure limits), and 0.1 PEL concentrations with high reproducibility. PMID:18950204

  8. Nanoporous Ti-metal film deposition using radio frequency magnetron sputtering technique for photovoltaic application.

    PubMed

    Sung, Youl-Moon; Paeng, Sung-Hwan; Moon, Byung-Ho; Kwak, Dong-Joo

    2012-02-01

    Nanoporous Ti-metal film electrode was fabricated by radio frequency (rf) magnetron sputtering technique on nanoporous TiO2 layer prepared by sol-gel combustion method and investigated with respect to its photo-anode properties of TCO-less DSCs. The porous Ti layer (approximately 1 microm) with low sheet resistance (approximately 17 Omega/sq.) can collect electrons from the TiO2 layer and allows the ionic diffusion of I(-)/I(3-) through the hole. The porous Ti layer with highly ordered columnar structure prepared by 8 mTorr sputtering shows the good impedance characteristics. The efficiency of prepared TCO-less DSCs sample is about 4.83% (ff: 0.6, Voc: 0.65 V, Jsc: 11.2 mA/cm2). PMID:22629960

  9. Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

    PubMed

    Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

    2011-02-01

    In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time. PMID:21456152

  10. Nanoporous ZnO nanostructures for photocatalytic degradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Ying, Yulong; Song, Tao; Huang, Hongwen; Peng, Xinsheng

    2013-02-01

    ZnO porous bamboo-leave-like nanorods and nanoporous networks were prepared by thermal conversion from Zn2CO3(OH)2ṡH2O bamboo-leave-like nanorods, Zn(OH)2 nanoparticle networks and Zn(OH)2 long nanostrand networks, respectively. Among them, the ZnO nanoporous networks prepared from Zn(OH)2 nanostrands had the highest surface area of 78.57 m2/g and presented the best photocatalytic decomposition of organics. The morphologies of the Zn(OH)2 nanostructures significantly depended on the solvent used for the precursors of aminoethanol and Zn(NO3)2 and then determined the corresponding structures and properties of the final ZnO nanostructures. The ethanol/water mixture solvent dramatically increased the stability of Zn(OH)2 nanostrands. This is very beneficial for the collection and application of Zn(OH)2 nanostrands.

  11. Electronic detection of dsDNA transition from helical to zipper conformation using graphene nanopores

    PubMed Central

    Sathe, Chaitanya; Girdhar, Anuj; Leburton, Jean-Pierre; Schulten, Klaus

    2014-01-01

    Mechanical manipulation of DNA, by forced extension, can lead to a structural transformation of double-stranded DNA (dsDNA) from a helical form to a linear zipper-like form. By employing classical molecular dynamics and quantum mechanical non-equilibrium Greens function-based transport simulations, we show the ability of graphene nanopores to discern different dsDNA conformations, in a helical to zipper transition, using transverse electronic conductance. In particular, conductance oscillations due to helical dsDNA vanish as dsDNA extends from helical to zipper form as it is transported through the nanopore. The predicted ability to detect conformational changes in dsDNA, via transverse electronic conductance, can widen the potential of graphene-based nanosensors for DNA detection. PMID:25325530

  12. Ultrasensitive cDNA Detection of Dengue Virus RNA Using Electrochemical Nanoporous Membrane-Based Biosensor

    PubMed Central

    Rai, Varun; Hapuarachchi, Hapuarachchige C.; Ng, Lee Ching; Soh, Siew Hwa; Leo, Yee Sin; Toh, Chee-Seng

    2012-01-01

    A nanoporous alumina membrane-based ultrasensitive DNA biosensor is constructed using 5′-aminated DNA probes immobilized onto the alumina channel walls. Alumina nanoporous membrane-like structure is carved over platinum wire electrode of 76 µm diameter dimension by electrochemical anodization. The hybridization of complementary target DNA with probe DNA molecules attached inside the pores influences the pore size and ionic conductivity. The biosensor demonstrates linear range over 6 order of magnitude with ultrasensitive detection limit of 9.55×10−12 M for the quantification of ss-31 mer DNA sequence. Its applicability is challenged against real time cDNA PCR sample of dengue virus serotype1 derived from asymmetric PCR. Excellent specificity down to one nucleotide mismatch in target DNA sample of DENV3 is also demonstrated. PMID:22927927

  13. Nanoporous gold catalysts for selective gas-phase oxidative coupling of methanol at low temperature.

    PubMed

    Wittstock, A; Zielasek, V; Biener, J; Friend, C M; Bäumer, M

    2010-01-15

    Gold (Au) is an interesting catalytic material because of its ability to catalyze reactions, such as partial oxidations, with high selectivities at low temperatures; but limitations arise from the low O2 dissociation probability on Au. This problem can be overcome by using Au nanoparticles supported on suitable oxides which, however, are prone to sintering. Nanoporous Au, prepared by the dealloying of AuAg alloys, is a new catalyst with a stable structure that is active without any support. It catalyzes the selective oxidative coupling of methanol to methyl formate with selectivities above 97% and high turnover frequencies at temperatures below 80 degrees C. Because the overall catalytic characteristics of nanoporous Au are in agreement with studies on Au single crystals, we deduced that the selective surface chemistry of Au is unaltered but that O2 can be readily activated with this material. Residual silver is shown to regulate the availability of reactive oxygen. PMID:20075249

  14. Temporal evolution of nanoporous layer in off-normally ion irradiated GaSb

    SciTech Connect

    Datta, D. P.; Garg, S. K.; Som, T.; Kanjilal, A.; Sahoo, P. K.; Kanjilal, D.

    2014-03-28

    Room temperature irradiation of GaSb by 60 keV Ar{sup +}-ions at an oblique incidence of 60° leads to simultaneous formation of a nanoporous layer and undulations at the interface with the underlying substrate. Interestingly, with increasing ion fluence, a gradual embedding of the dense nanoporous layer takes place below ridge-like structures (up to the fluence of 1 × 10{sup 17} ions cm{sup −2}), which get extended to form a continuous layer (at fluences ≥4 × 10{sup 17} ions cm{sup −2}). Systematic compositional analyses reveal the co-existence of Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3} in the surface layer. The results are discussed in terms of a competition between ion-induced defect accumulation and re-deposition of sputtered atoms on the surface.

  15. Nanoscale Bio-engineering Solutions for Space Exploration: The Nanopore Sequencer

    NASA Technical Reports Server (NTRS)

    Stolc, Viktor; Cozmuta, Ioana

    2004-01-01

    Characterization of biological systems at the molecular level and extraction of essential information for nano-engineering design to guide the nano-fabrication of solid-state sensors and molecular identification devices is a computational challenge. The alpha hemolysin protein ion channel is used as a model system for structural analysis of nucleic acids like DNA. Applied voltage draws a DNA strand and surrounding ionic solution through the biological nanopore. The subunits in the DNA strand block ion flow by differing amounts. Atomistic scale simulations are employed using NASA supercomputers to study DNA translocation, with the aim to enhance single DNA subunit identification. Compared to protein channels, solid-state nanopores offer a better temporal control of the translocation of DNA and the possibility to easily tune its chemistry to increase the signal resolution. Potential applications for NASA missions, besides real-time genome sequencing include astronaut health, life detection and decoding of various genomes.

  16. Surface enhanced Raman scattering detection of single R6G molecules on nanoporous gold films

    NASA Astrophysics Data System (ADS)

    Liu, Hongwen; Zhang, L.; Yamaguchi, Y.; Iwasaki, H.; Inouye, Y.; Xue, Q. K.; Chen, M. W.

    2011-03-01

    Detecting single molecules with high sensitivity and molecular specificity is of great practical interest in many fields such as chemistry, biology, medicine, and pharmacology. For this purpose, cheap and highly active substrates are of crucial importance. Recently, nanoporous metals (NPMs), with a three-dimensional continuous network structure and pore channels usually much smaller than the wavelength of visible light, revealed outstanding optical properties in surface enhanced Raman scattering (SERS). In this work, we further modify the nanoporous gold films by growing a high density of gold nano-tips on the surface. Extremely focused electromagnetic fields can be produced at the apex of the nano-tips, resulting in so-called hot spots. With this NPM-based and affordable substrate, single molecule-detection is achievable with ultrahigh enhancement in SERS.

  17. Detection of biological analytes using nanomechanical infrared spectroscopy with a nanoporous microcantilever

    NASA Astrophysics Data System (ADS)

    Lee, Dongkyu; Kim, Seonghwan; Thundat, Thomas

    2013-05-01

    The highly sensitive nanoporous cantilever beam without immobilized receptors was combined with highly selective mid-infrared (IR) spectroscopy for molecular recognition of analytes using characteristic molecular vibrations. Unlike conventional IR spectroscopy, in addition, the detection sensitivity and resolution are drastically enhanced by combining high power tunable quantum cascade laser with a nanoporous cantilever having large surface area, low modulus, and nanowell structures. Further, analytes can be easily loaded on the porous microcantilever without receptor due to nanowells. In addition, orthogonal signals, variations in the mass and IR spectrum, provide more reliable and quantitative results including physical as well as chemical information of samples. We have used this technique to rapidly identify single and double stranded DNA.

  18. Single-molecule DNA detection using a novel SP1 protein nanopore.

    PubMed

    Wang, Hai-Yan; Li, Yang; Qin, Li-Xia; Heyman, Arnon; Shoseyov, Oded; Willner, Itamar; Long, Yi-Tao; Tian, He

    2013-02-28

    SP1 protein as a new type of biological nanopore is described and is utilized to distinguish single-stranded DNA at the single-molecule level. Using the SP1 nanopore to investigate single molecule detection broadens the existing research areas of pore-forming biomaterials from unsymmetrical biological nanopores to symmetrical biological nanopores. This novel nanopore could provide a good candidate for single-molecule detection and characterization of biomaterial applications. PMID:23340583

  19. Nanopore Connectivity, Wettability and Fluid Migration in Mudrocks

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Hu, Q.; Barber, T.; Md Golam, K.

    2015-12-01

    Micro(nano)scopic pore characteristics (e.g., pore size, pore-size distribution, and pore connectivity) of mudrocks, implicated by their mixed wettability, control macroscopic fluid flow and hydrocarbon production. This work discusses various approaches to investigating pore structure (both geometry and topology) of several mudrocks of leading U.S. plays (Barnett, Bakken/Three Forks, and Utica), and the presence and connection of mixed wettability associated with compositional phases. Results show that these mudrocks have very limited edge-accessible pore spaces. This is shown from low pore connectivity behavior of fluid imbibition, steep decline of edge-accessible porosity from vacuum saturation, the heterogeneous presence of only trace amount of diffusing tracers beyond a few mm from a sample edge, and limited connected pathways from high-pressure injection of traced n-decane at 414 MPa. As mudrocks contain distinct hydrophobic organic materials (e.g., kerogen), as well as hydrophilic and/or hydrophobic minerals, different nano-sized tracers in two wettability fluids (API brine and n-decane) were developed to interrogate their pore spaces and connectivity. For two molecular tracers in n-decane with the sizes of 1.393 nm×0.287 nm×0.178 nm for 1-iododecane and 1.273 nm×0.919 nm×0.785 nm for trichlorooxobis (triphenylphosphine) rhenium, much less penetration was observed for wider molecules of organic-Re in these mudrocks with median pore-throats of around 5 nm, indicating the entangling of nano-sized molecules in nanopore spaces of mudrocks. The sparse nanopore space connection within the mudrock matrix, implicated by mixed wettability, could lead to limited movement of nano-sized hydrocarbon molecules and fracture-matrix interactions in fractured reservoirs, and consequently steep initial production decline and low recovery.

  20. Theoretical study of intermolecular interactions in nanoporous networks on boron doped silicon surface

    NASA Astrophysics Data System (ADS)

    Boukari, Khaoula; Duverger, Eric; Hanf, Marie-Christine; Stephan, Régis; Sonnet, Philippe

    2014-11-01

    Supramolecular networks on a doped boron silicon surface under ultra high vacuum (UHV) have been recently obtained (Makoudi et al., 2013). The used molecule contains different end-groups, bearing either bromine, iodine or hydrogen atoms denoted 1,3,5-tri(4‧-bromophenyl)benzene (TBB), 1,3,5-tri(4-iodophenyl)benzene (TIB) and 1,3,5-triphenyl-benzene (THB). To explain the formation of the nanoporous structures, interactions of the type aryl-X⋯H hydrogen bonds (X being a halogen atom) have been proposed. In order to obtain a complete insight of the stabilizing interaction in these networks adsorbed on the Si(1 1 1)√3x√3R30°-boron surface, we present a full density-functional-theory study taking the van der Waals interactions into account. We investigated the energetic and structural properties of three different nanoporous networks constituted by TBB, TIB and THB molecules. The electronic studies allow us to identify hydrogen bond and dipole-dipole intermolecular interactions in the supramolecular halogen networks, whereas only dipole-dipole interactions are present in the 1,3,5-triphenyl-benzene nanoporous network.