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Sample records for nanostructural features formed

  1. Molecular-level control of feature separation in one-dimensional nanostructure assemblies formed by biomolecular nanolithography.

    PubMed

    Woehrle, Gerd H; Warner, Marvin G; Hutchison, James E

    2004-07-06

    In this paper, we present a convenient and reliable method to organize small gold nanoparticles (d(CORE) = 1.5 nm) into linear chains with precisely controlled interparticle spacing over a range of 1.5-2.8 nm through biomolecular nanolithography. Controlling the feature separations of 1 to a few nanometers with angstrom-level precision is a key requirement in electronic and optical applications of nanostructures to tune the properties of the nanostructures and manipulate the interactions between neighboring structures. Here, chains are formed in solution by utilizing functional-group-directed self-assembly to organize ligand-stabilized gold nanoparticles onto DNA templates. The spacing between neighboring nanoparticles can be controlled chemically and tuned at the molecular level by utilizing nanoparticles possessing ligand shells of varying thickness to achieve angstrom-level resolution at spacings of 1.5, 2.1, and 2.8 nm. The small standard deviation (< or = 20%) in the values for the interparticle spacing illustrates the reproducibility of the approach. Because the interparticle spacing is enforced by the ligand shell rather than the scaffold, the spacing is uniform even in nonlinear sections of the chain. We further show that the assembly process is robust and produces extended linear nanoparticle chains of up to 1 microm in length and a total coverage of > 90%. All structures and interparticle spacings were analyzed using transmission electron microscopy. Our results demonstrate the potential of scaffold-assisted assembly approaches for patterning features with tunable dimensions on a length scale that is important for future applications of these materials in nanoscale electronics and optics.

  2. Composite materials formed with anchored nanostructures

    DOEpatents

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2015-03-10

    A method of forming nano-structure composite materials that have a binder material and a nanostructure fiber material is described. A precursor material may be formed using a mixture of at least one metal powder and anchored nanostructure materials. The metal powder mixture may be (a) Ni powder and (b) NiAl powder. The anchored nanostructure materials may comprise (i) NiAl powder as a support material and (ii) carbon nanotubes attached to nanoparticles adjacent to a surface of the support material. The process of forming nano-structure composite materials typically involves sintering the mixture under vacuum in a die. When Ni and NiAl are used in the metal powder mixture Ni.sub.3Al may form as the binder material after sintering. The mixture is sintered until it consolidates to form the nano-structure composite material.

  3. Supramolecular Nanostructures Formed by Anticancer Drug Assembly

    PubMed Central

    Cheetham, Andrew G.; Zhang, Pengcheng; Lin, Yi-an; Lock, Lye Lin; Cui, Honggang

    2013-01-01

    We report here a supramolecular strategy to directly assemble the small molecular hydrophobic anticancer drug camptothecin (CPT) into discrete, stable, well-defined nanostructures with a high and quantitative drug loading. Depending on the number of CPTs in the molecular design, the resulting nanostructures can be either nanofibers or nanotubes, and have a fixed CPT loading content ranging from 23% to 38%. We found that formation of nanostructures provides protection for both the CPT drug and the biodegradable linker from the external environment and thus offers a mechanism for controlled release of CPT. Under tumor-relevant conditions, these drug nanostructures can release the bioactive form of CPT and show in vitro efficacy against a number of cancer cell lines. This strategy can be extended to construct nanostructures of other types of anticancer drugs, and thus presents new opportunities for the development of self-delivering drugs for cancer therapeutics. PMID:23379791

  4. Nanostructural features of demosponge biosilica.

    PubMed

    Weaver, James C; Pietrasanta, Lía I; Hedin, Niklas; Chmelka, Bradley F; Hansma, Paul K; Morse, Daniel E

    2003-12-01

    Recent interest in the optical and mechanical properties of silica structures made by living sponges, and the possibility of harnessing these mechanisms for the synthesis of advanced materials and devices, motivate our investigation of the nanoscale structure of these remarkable biomaterials. Scanning electron and atomic force microscopic (SEM and AFM) analyses of the annular substructure of demosponge biosilica spicules reveals that the deposited material is nanoparticulate, with a mean particle diameter of 74+/-13 nm. The nanoparticles are deposited in alternating layers with characteristic etchant reactivities. Further analyses of longitudinally fractured spicules indicate that each deposited layer is approximately monoparticulate in thickness and exhibits extensive long range ordering, revealing an unanticipated level of nanoscale structural complexity. NMR data obtained from differentially heated spicule samples suggest that the etch sensitivity exhibited by these annular domains may be related to variation in the degree of silica condensation, rather than variability in the inclusion of organics. In addition, AFM phase imaging in conjunction with results obtained from HF and alkaline etching experiments suggest that at various stages in spicule biosynthesis, regions of unusually low silica condensation are deposited, indicating a possible interruption in normal spicule formation. While this discovery of nanoparticulate silica aggregation in demosponge skeletal elements is likely to reflect the intrinsic kinetic tendency of silica to form such particles during polycondensation, the heirarchical organization of these nanoparticles is biologically unique.

  5. Ordered biological nanostructures formed from chaperonin polypeptides

    NASA Technical Reports Server (NTRS)

    Trent, Jonathan D. (Inventor); McMillan, R. Andrew (Inventor); Kagawa, Hiromi (Inventor); Paavola, Chad D. (Inventor)

    2010-01-01

    The following application relates to nanotemplates, nanostructures, nanoarrays and nanodevices formed from wild-type and mutated chaperonin polypeptides, methods of producing such compositions, methods of using such compositions and particular chaperonin polypeptides that can be utilized in producing such compositions.

  6. Microfabricated structures and devices featuring nanostructured titania thin films

    NASA Astrophysics Data System (ADS)

    Monkowski, Adam J.

    2007-05-01

    When titanium reacts with hydrogen peroxide at 80°C--100°C, a nanostructured titania (NST) thin film is formed on the titanium surface. This nanostructured film is particularly suited for integration with thin film and bulk microfabrication techniques. The ability to manufacture devices in a batch format is a principal advantage of microfabrication-based production. To reliably produce arrays of micro-patterned NST thin films on the wafer scale, a patterning guideline must be considered. The formation of NST relies on a re-deposition process; adequate ti-peroxo species must be generated and remain at the solid-solution interface. Numerical analysis of the characteristic transient diffusion behavior for various micro-patterns has been compared with experimental data to generate a criterion to guide the design of NST micro-patterns. Wafer scale arrays of NST micro gas-sensors have been fabricated using standard thin film techniques. Sensing elements are 20 mum on a side. High sensitivity to hydrogen is achieved by modification of the sensors with platinum nanoparticles. When exposed to a 10 mT partial pressure of hydrogen at 250°C, the functionalized devices exhibit more than one order of magnitude resistance decrease with a response time of approximately 7 sec. Titanium microstructures formed using the titanium ICP deep etch (TIDE) process have been integrated with NST films to produce an ordered nanostructure-microstructure composite (3D-NST). The process developed allows for the incorporation of a planar top surface, advantageous for bonding and sealing applications, in which the nanostructured thin film is formed only on feature sidewalls and floors. When titanium microstructures are spaced less than 1 mum apart, titania nanostructures bridge adjacent features. NST and 3D-NST structures have been assembled and tested in a dye-sensitized solar cell (DSSC) device. The NST film is approximately 900nm thick; this yielded a DSSC with an efficiency of 1.8%, similar

  7. Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of the Effect of Mn on the Nanostructural Features formed in Irradiated Fe-Cu-Mn Alloys

    SciTech Connect

    Glade, S C; Wirth, B D; Asoka-Kumar, P; Odette, G R; Sterne, P A; Howell, R H

    2003-02-27

    The size, number density and composition of the nanometer defects responsible for the hardening and embrittlement in irradiated Fe-0.9wt.% Cu and Fe-0.9wt.% Cu-1.0wt% Mn model reactor pressure vessel alloys were measured using small angle neutron scattering and positron annihilation spectroscopy. These alloys were irradiated at 290 C to relatively low neutron fluences (E > 1 MeV, 6.0 x 10{sup 20} to 4.0 x 10{sup 21} n/m{sup 2}) in order to study the effect of manganese on the nucleation and growth of copper rich precipitates and secondary defect features. Copper rich precipitates were present in both alloys following irradiation. The Fe-Cu-Mn alloy had smaller precipitates and a larger number density of precipitates, suggesting Mn segregation at the iron matrix-precipitate interface which reduces the interfacial energy and in turn the driving force for coarsening. Mn also retards the precipitation kinetics and inhibits large vacancy cluster formation, suggesting a strong Mn-vacancy interaction which reduces radiation enhanced diffusion.

  8. Charge-free method of forming nanostructures on a substrate

    DOEpatents

    Hoffbauer; Mark , Akhadov; Elshan

    2010-07-20

    A charge-free method of forming a nanostructure at low temperatures on a substrate. A substrate that is reactive with one of atomic oxygen and nitrogen is provided. A flux of neutral atoms of least one of oxygen and nitrogen is generated within a laser-sustained-discharge plasma source and a collimated beam of energetic neutral atoms and molecules is directed from the plasma source onto a surface of the substrate to form the nanostructure. The energetic neutral atoms and molecules in the beam have an average kinetic energy in a range from about 1 eV to about 5 eV.

  9. Nanostructured thermoelectrics: big efficiency gains from small features.

    PubMed

    Vineis, Christopher J; Shakouri, Ali; Majumdar, Arun; Kanatzidis, Mercouri G

    2010-09-22

    The field of thermoelectrics has progressed enormously and is now growing steadily because of recently demonstrated advances and strong global demand for cost-effective, pollution-free forms of energy conversion. Rapid growth and exciting innovative breakthroughs in the field over the last 10-15 years have occurred in large part due to a new fundamental focus on nanostructured materials. As a result of the greatly increased research activity in this field, a substantial amount of new data--especially related to materials--have been generated. Although this has led to stronger insight and understanding of thermoelectric principles, it has also resulted in misconceptions and misunderstanding about some fundamental issues. This article sets out to summarize and clarify the current understanding in this field; explain the underpinnings of breakthroughs reported in the past decade; and provide a critical review of various concepts and experimental results related to nanostructured thermoelectrics. We believe recent achievements in the field augur great possibilities for thermoelectric power generation and cooling, and discuss future paths forward that build on these exciting nanostructuring concepts.

  10. Nanostructured thermoelectrics : big efficiency gains from small features.

    SciTech Connect

    Vineis, C. J.; Shakouri, A.; Majumdar, A.; Kanatzidis, M. G.; Materials Science Division; Northwestern Univ.; Univ.of California at Santa Cruz; Univ. of California at Berkeley

    2010-01-01

    The field of thermoelectrics has progressed enormously and is now growing steadily because of recently demonstrated advances and strong global demand for cost-effective, pollution-free forms of energy conversion. Rapid growth and exciting innovative breakthroughs in the field over the last 10-15 years have occurred in large part due to a new fundamental focus on nanostructured materials. As a result of the greatly increased research activity in this field, a substantial amount of new data - especially related to materials - have been generated. Although this has led to stronger insight and understanding of thermoelectric principles, it has also resulted in misconceptions and misunderstanding about some fundamental issues. This article sets out to summarize and clarify the current understanding in this field; explain the underpinnings of breakthroughs reported in the past decade; and provide a critical review of various concepts and experimental results related to nanostructured thermoelectrics. We believe recent achievements in the field augur great possibilities for thermoelectric power generation and cooling, and discuss future paths forward that build on these exciting nanostructuring concepts.

  11. Platinum nanostructures formed by femtosecond laser irradiation in water

    SciTech Connect

    Huo Haibin; Shen Mengyan

    2012-11-15

    Platinum nanostructures with various morphologies, such as spike-like, ripple-like and array-like structures, have been fabricated by 400 nm and 800 nm femtosecond laser irradiation in water. Different structures can be formed on the surfaces as a function of the laser wavelength, the fluence and scan methods. The reflectance measurements of these structures show much larger absorption on the irradiated surfaces than untreated platinum surfaces.

  12. Nanostructures formed by cyclodextrin covered aminobenzophenones through supramolecular self assembly

    NASA Astrophysics Data System (ADS)

    Rajendiran, N.; Sankaranarayanan, R. K.; Saravanan, J.

    2014-06-01

    Cyclodextrin (α and β) based nanostructures formed with 2-aminobenzophenone, 3-aminobenzophenone through the supramolecular self assembly are studied by absorption, fluorescence, time-resolved fluorescence, SEM, TEM, FT-IR, DSC, PXRD and 1H NMR. The unequal layer by layer nanosheets and nanoribbons are formed through self assembly of 3ABP/CD inclusion complexes. 2ABP/α-CD complex nanostructures show the self assembly hierarchical thread structure and β-CD complexes displays a nanobrick structure. The formation of nanostructures are prearranged to Hsbnd O⋯H, NH2⋯O and H2N⋯H intermolecular hydrogen bond between individual complexes. The absorption and fluorescence spectral changes explicit formation of 1:1 inclusion complexes and solvent study demonstrate the ESIPT and TICT present in both molecules. The thermodynamic parameters (ΔH, ΔG and ΔS) of 2ABP and 3ABP molecule and the inclusion complexes were determined from semiempirical PM3 calculations.

  13. Characterization of Nanostructural Features in Irradiated Reactor Pressure Vessel Model Alloys

    SciTech Connect

    Wirth, B D; Odette, G R; Asoka-Kumar, P; Howell, R H; Sterne, P A

    2001-08-01

    Irradiation embrittlement in nuclear reactor pressure vessel steels results from the formation of a high number density of nanometer-sized copper rich precipitates and sub-nanometer defect-solute clusters. We present results of small angle neutron scattering (SANS) and positron annihilation spectroscopy (PAS) characterization of the nanostructural features formed in binary and ternary Fe-Cu-Mn alloys irradiated at {approx}290 C. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of copper-manganese precipitates and smaller vacancy-copper-manganese clusters. The PAS characterization, including both Doppler broadening and positron lifetime measurements, indicates the presence of essentially defect-free Cu precipitates in the Fe-Cu-Mn alloy and vacancy-copper clusters in the Fe-Cu alloy. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of copper-rich precipitates and vacancy solute cluster complexes and tend to discount high Fe concentrations in the CRPs.

  14. Waste Form Features, Events, and Processes

    SciTech Connect

    R. Schreiner

    2004-10-27

    The purpose of this report is to evaluate and document the inclusion or exclusion of the waste form features, events and processes (FEPs) with respect to modeling used to support the Total System Performance Assessment for License Application (TSPA-LA). A screening decision, either Included or Excluded, is given for each FEP along with the technical bases for screening decisions. This information is required by the Nuclear Regulatory Commission (NRC) in 10 CFR 63.114 (d, e, and f) [DIRS 156605]. The FEPs addressed in this report deal with the issues related to the degradation and potential failure of the waste form and the migration of the waste form colloids. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA, (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical bases for exclusion from TSPA-LA (i.e., why the FEP is excluded). This revision addresses the TSPA-LA FEP list (DTN: MO0407SEPFEPLA.000 [DIRS 170760]). The primary purpose of this report is to identify and document the analyses and resolution of the features, events, and processes (FEPs) associated with the waste form performance in the repository. Forty FEPs were identified that are associated with the waste form performance. This report has been prepared to document the screening methodology used in the process of FEP inclusion and exclusion. The analyses documented in this report are for the license application (LA) base case design (BSC 2004 [DIRS 168489]). In this design, a drip shield is placed over the waste package and no backfill is placed over the drip shield (BSC 2004 [DIRS 168489]). Each FEP may include one or more specific issues that are collectively described by a FEP name and a FEP description. The FEP description may encompass a single feature, process or event, or a few closely related or coupled processes if the entire FEP can be addressed by a single specific screening argument or TSPA-LA disposition. The FEPs are

  15. Electrophysical properties and structural features of shungite (natural nanostructured carbon)

    NASA Astrophysics Data System (ADS)

    Golubev, E. A.

    2013-05-01

    This paper presents the results of investigations of the electrical conductive properties with a nanoscale locality at nanoampere currents and the results of an analysis of the correlation between the electrical conductivity and structural features of natural glassy carbon, i.e., shungite. The investigations have been performed using atomic force microscopy, electric force spectroscopy, scanning spreading resistance microscopy, X-ray spectroscopic analysis, and Raman spectroscopy. It has been found that there are differences in electrical conductive properties of the structurally similar shungite samples formed under different PT conditions. Based on the analysis of the structural parameters and specific features of the shungite compositions, it has been shown that the effect of intercalation of impurities into boundary layers of graphene sheets has the most significant influence on the electrical and physical properties of the shungites. The differences in types and values of conductivity of the shungite samples are determined by the different degrees of intercalation.

  16. Optical security features and filters using plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Gallinet, Benjamin; Lütolf, Fabian; Duempelmann, Luc; Basset, Guillaume; Luu-Dinh, Angélique; Schnieper, Marc; Bosshard, Christian

    2017-02-01

    Plasmonics involves the interaction of light with metallic structures at the nanoscale, which enables in particular the generation of strong reflection and absorption effects in the visible and near infrared range. The fabrication of plasmonic nanostructures using ultra-violet (UV) imprint and thin metallic coatings is reported. Wafer-scale fabrication and process compatibility with cost-efficient roll-to-roll production are demonstrated, which paves the road towards an industrial implementation. The color, phase, polarization and direction of the transmitted light are controlled by tuning the process parameters and the symmetry of the nanostructures. A family of devices is presented, for which the potential for sensing, filtering, anticounterfeiting and optical security is evaluated.

  17. Surface-enhanced infrared absorption studies of copper nanostructures formed by oblique-angle deposition

    NASA Astrophysics Data System (ADS)

    Henry, William A.; Biris, Alexandru S.; Watanabe, Fumiya; Huntington, Taylor E.; Owen, Aaron R.; Price, Adam S.; Golden, Jon W.; Primm, Katherine M.; Wilde, Brandon M.; Sweere, Morgan D.; Denton, Caleb N.; Branch, Bakarie S.; Banh, Thomas M.; Lindsey, Mary E.; Perry, Donald A.

    2016-10-01

    It is demonstrated that Cu nanostructures fashioned by oblique angle deposition (OAD) of gaseous Cu atoms onto CaF2 substrates have SEIRA enhancement factors that are close to par with Ag or Au nanostructures formed using vapor deposition at a normal deposition angle. Cu nanostructures grown at normal angle show about 5× in SEIRA enhancement of a p-nitrobenzoic acid (PNBA) monolayer and have a range of over 100 nm in particle size. Conversely, Cu nanostructures deposited by OAD show SEIRA enhancement of approximately 40× and are more uniform with approximate circular shapes averaging 25 nm and spacing less than 10 nm.

  18. Martian Features Formed When Material Moves Downslope

    NASA Image and Video Library

    2013-06-11

    As on the Earth, many processes can move material down a Martian slope. This graphic compares seven different types of features observed on Mars that appear to result from material flowing or sliding or rolling down slopes.

  19. Nanostructured gold architectures formed through high pressure-driven sintering of spherical nanoparticle arrays.

    PubMed

    Wu, Huimeng; Bai, Feng; Sun, Zaicheng; Haddad, Raid E; Boye, Daniel M; Wang, Zhongwu; Huang, Jian Yu; Fan, Hongyou

    2010-09-22

    We have demonstrated pressure-directed assembly for preparation of a new class of chemically and mechanically stable gold nanostructures through high pressure-driven sintering of nanoparticle assemblies at room temperature. We show that under a hydrostatic pressure field, the unit cell dimension of a 3D ordered nanoparticle array can be reversibly manipulated allowing fine-tuning of the interparticle separation distance. In addition, 3D nanostructured gold architecture can be formed through high pressure-induced nanoparticle sintering. This work opens a new pathway for engineering and fabrication of different metal nanostructured architectures.

  20. Manipulating Surface Energy to form Compound Semiconductor Nanostructures

    NASA Astrophysics Data System (ADS)

    DeJarld, Matthew T.

    Nanostructures have been lauded for their quantum confinement capabilities and potential applications in future devices. Compound semiconductor nanostructures are being integrated into the next generation of photovoltaic and light emitting devices to take advantage of their unique optical characteristics. Despite their promise, adoption of nanostructure based devices has been slow. This is due in large part to difficulties in effective fabrication and processing steps. By manipulating the surface energy of various components during growth, we can control the final structure and corresponding optoelectronic characteristics. Specifically I will present on GaSb quantum dots embedded in GaAs and GaAs nanowires using novel substrate and catalyst materials. GaSb quantum dots embedded in a GaAs matrix are ideal for devices that require capture of minority carriers as they exhibit a type II band offset with carrier concentration in the valence band. However, during GaAs capping, there is a strong driving force for the dot to demolish into a distribution of intact dots, rings, and GaSb material clusters. We demonstrate the ability to mitigate this effect using both chemical and kinetic means: we alter the surface chemistry via the addition of aluminum, and use droplet epitaxy as an alternative quantum dot formation method. Secondly, the growth of high quality GaAs on silicon has always been restricted due to material incompatibilities. With the emergence of increasingly smaller low power electronics, there is a demand to integrate optoelectronic devices directly on the surface of CMOS sensor stacks. Utilizing the vapor-liquid-solid growth mechanism we are able to demonstrate the growth of high quality GaAs nanowires on polycrystalline substrates at low temperatures. This allows for the growth of III-V nanowire based devices directly on the metal pads of pre-packaged CMOS chips. We also investigate the potential use of bismuth as an alternative to gold for catalyzing

  1. Light-reducible dissipative nanostructures formed at the solid-liquid interface.

    PubMed

    Soejima, Tetsuro; Amako, Yuta; Ito, Seishiro; Kimizuka, Nobuo

    2014-12-02

    Dissipative structures are macroscopic or even larger ordered structures that emerge under conditions far from thermodynamic equilibrium. In contrast, molecular self-assembly has been investigated near at the thermodynamic equilibrium, which provides basically smaller, nano-to-micron sized structures. In terms of the formation principles, there exists an essential gap between the dissipative structures and molecular self-assemblies. To fill this gap, molecular self-assembly of light-reducible organic-inorganic ion pairs was investigated under far-from-equilibrium conditions. When solid films of tetraalkylammonium hexafluorophosphate were immersed in aqueous Au(OH)4(-) and immediately photoirradiated, gold nanowires are formed at the solid-aqueous interface. On the other hand, such nanowires were not formed when the photoirradiation was conducted for the specimens after a prolonged immersion period of 60 min. These observations indicate spontaneous growth of dissipative nanofibrous self-assemblies consisting of light-reducible ion pairs [tetraalkylammonium ion][Au(OH)4(-)] at the interface and their photoreduction to give developed nanowires. These nanowires are not available by the photoreduction of Au(OH)4(-) ions under conditions near at the thermodynamic equilibrium. A picture for the dissipative nanostructures is obtained: the formation of amphiphilic light-reducible nanowire structures is based on the static self-assembly near at the thermodynamic equilibrium, whereas their spontaneous, anisotropic growth from the interface to the aqueous phase is directed by dynamic, dissipative self-assembly phenomena under the far-from-equilibrium conditions. Thus, the both elements of dissipative self-assembly (dynamic) and static molecular self-assembly fuse together at the nanoscale, which is an essential feature of the dissipative nanostructures.

  2. Featured Image: A Filament Forms and Erupts

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-06-01

    This dynamic image of active region NOAA 12241 was captured by the Solar Dynamics Observatorys Atmospheric Imaging Assembly in December 2014. Observations of this region from a number of observatories and instruments recently presented by Jincheng Wang (University of Chinese Academy of Sciences) and collaborators reveal details about the formation and eruption of a long solar filament. Wang and collaborators show that the right part of the filament formed by magnetic reconnection between two bundles of magnetic field lines, while the left part formed as a result of shearing motion. When these two parts interacted, the filament erupted. You can read more about the teams results in the article linked below. Also, check out this awesome video of the filament formation and eruption, again by SDO/AIA:http://cdn.iopscience.com/images/0004-637X/839/2/128/Full/apjaa6bf3f1_video.mp4CitationJincheng Wang et al 2017 ApJ 839 128. doi:10.3847/1538-4357/aa6bf3

  3. Nanostructural and biogeochemical features of the crinoid stereom

    NASA Astrophysics Data System (ADS)

    Gorzelak, P.; Stolarski, J.; Mazur, M.; Marrocchi, Y.; Meibom, A.; Chalmin, E.

    2009-04-01

    Representatives of all echinoderm clades (e.g., echinoids, holothuroids, ophiuroids, asteroids, and crinoids) form elaborate calcitic (polymorph of calcium carbonate) skeletons composed of numerous plates. Each plate consists of a three-dimensional meshwork of mineral trabeculae (stereom) that results from precisely orchestrated biomineralization processes. Individual skeletal plates behave as single calcite crystals as shown by X-ray diffraction and polarizing microscopy, however, their physico-chemical properties differ significantly from the properties of geologic or synthetic calcites. For example, echinoderm bio-calcite does not show cleavage planes typical of calcite but reveals conchoidal fracture surfaces that reduce the brittleness of the material. The unique properties of echinoderm bio-calcite result from intimate involvement of organic molecules in the biomineralization process and their incorporation into the crystal structure. Remnants of echinoderm skeleton are among the most frequently found fossils in the Mesozoic and Palaeozoic rocks thus, in order to use them as environmental proxies, it is necessary to understand the degree of biological ("vital effect") and inorganic control over their formation. Here, we show first nanoscale structural and biogeochemical properties of the stereom of extant and fossil crinoids. Using FESEM and AFM imaging techniques we show that the skeleton has nanocomposite structure: individual grains have ca. 100 nm in diameter and occasionally form larger aggregates. Fine scale geobiochemical mappings of crinoid plates (NanoSIMS microprobe) show that Mg is distributed heterogeneously in the stereom with higher concentration in the middle part of the trabecular bars. Although organic components constitute only ca. 0.10-0.26 wt% of modern echinoderm bio-calcite, in situ synchrotron sulphur K-edge x-ray absorption near edge structure (XANES) spectra show that the central parts of stereom bars contain higher levels of SO4 that

  4. Eigenanalysis of morphological diversity in silicon random nanostructures formed via resist collapse

    NASA Astrophysics Data System (ADS)

    Naruse, Makoto; Hoga, Morihisa; Ohyagi, Yasuyuki; Nishio, Shumpei; Tate, Naoya; Yoshida, Naoki; Matsumoto, Tsutomu

    2016-11-01

    Nano-artifact metrics is an information security principle and technology that exploits physically uncontrollable processes occurring at the nanometer-scale to protect against increasing security threats. Versatile morphological patterns formed on the surfaces of planar silicon devices originating from resist collapse are one of the most unique and useful vehicles for nano-artifact metrics. In this study, we demonstrate the eigenanalysis of experimentally fabricated silicon random nanostructures, through which the diversity and the potential capacity of identities are quantitatively characterized. Our eigenspace-based approach provides intuitive physical pictures and quantitative discussions regarding the morphological diversity of nanostructured devices while unifying measurement stability, which is one of the most important concerns regarding security applications. The analysis suggests approximately 10115 possible identities per 0.18-μm2 nanostructure area, indicating the usefulness of nanoscale versatile morphology. The presented eigenanalysis approach has the potential to be widely applicable to other materials, devices, and system architectures.

  5. Nanostructured Arrays Formed by Finely Focused Ion Beams

    SciTech Connect

    Budai, J.D.; Datsos, P.G.; Feldman, L.C.; Heinig, K.-H.; Meldrum, A.; Strobel, M.; Thomas, K.A.; Warmack, R.J.; White, C.W.; Zuhr, R.A.

    1998-11-30

    Amorphous, polycrystalline, and single crystal nanometer dimension particles can be formed in a variety of substrates by ion implantation and subsequent annealing. Such composite colloidal materials exhibit unique optical properties that could be useful in optical devices, switches, and waveguides. However colloids formed by blanket implantation are not uniform in size due to the nonuniform density of the implant, resulting in diminution of the size dependent optical properties. The object of the present work is to form more uniform size particles arranged in a 2-dimensional lattice by using a finely focused ion beam to implant identical ion doses only into nanometer size regions located at each point of a rectangular lattice. Initial work is being done with a 30 keV Ga beam implanted into Si. Results of particle formation as a function of implant conditions as analyzed by Rutherford backscattering, x-ray analysis, atomic force microscopy, and both scanning and transmission electron microscopy will be presented and discussed.

  6. Method of making nanostructured glass-ceramic waste forms

    SciTech Connect

    Gao, Huizhen; Wang, Yifeng; Rodriguez, Mark A.; Bencoe, Denise N.

    2014-07-08

    A waste form for and a method of rendering hazardous materials less dangerous is disclosed that includes fixing the hazardous material in nanopores of a nanoporous material, reacting the trapped hazardous material to render it less volatile/soluble, and vitrifying the nanoporous material containing the less volatile/soluble hazardous material.

  7. Studies of nanostructures formed in T-10 tokamak

    NASA Astrophysics Data System (ADS)

    Kolbasov, B. N.; Stankevich, V. G.; Svechnikov, N. Yu; Lebedev, A. M.; Menshikov, K. A.; Rajarathnam, D.; Somenkov, V. A.; Trunova, V. A.; Veligzhanin, A. A.; Zubavichus, Y. V.

    2011-06-01

    According to the X-ray diffraction (XRD) studies, hydrocarbon films and flakes formed under deuterium plasma discharges in T-10 tokamak are amorphous with graphene-like sheets. They have atomic ratio (D + H)/C about 1 and higher. The XRD peak positions revealed the presence of structural defects with interplane distances of 0.12, 0.24 and 0.66 nm. The peak widths gave the in-plane sizes of the scattering structures equal to about 1 nm. The properties of such films were studied with application of small-angle and wide-angle X-ray scattering measurements, neutron diffraction and other techniques. These experiments have shown that the films contain about 63% of sp3 and ~37% of sp2 states. X-ray fluorescence spectroscopy employing synchrotron radiation revealed that the films contain at least 12 impurities of Fe, Mo, Cr, Ni, Nb and other transition metals. Difference between film properties on its opposite sides was revealed using Fourier-transform infrared spectroscopy and analysis of current-voltage characteristics (CVC). On the wall facing side of the film, graphite-like Csp2 structures dominate. On the plasma facing side, diamond-like Csp3 structures prevail. Deuterium retention can be monitored by two groups of vibrational sp3 modes with different oscillator strengths, depending on the amount of deuterium in films.

  8. Study of the technology of the plasma nanostructuring of silicon to form highly efficient emission structures

    SciTech Connect

    Galperin, V. A.; Kitsyuk, E. P.; Pavlov, A. A.; Shamanaev, A. A.

    2015-12-15

    New methods for silicon nanostructuring and the possibility of raising the aspect ratios of the structures being formed are considered. It is shown that the technology developed relates to self-formation methods and is an efficient tool for improving the quality of field-emission cathodes based on carbon nanotubes (CNTs) by increasing the Si–CNT contact area and raising the efficiency of the heat sink.

  9. Flavonol-carbon nanostructure hybrid systems: a DFT study on the interaction mechanism and UV/Vis features.

    PubMed

    García, Gregorio; Atilhan, Mert; Aparicio, Santiago

    2016-02-14

    Flavonols are a class of natural compounds with potential biological and pharmacological applications. They are also natural pigments responsible for the diversity of colors in plants. Flavonols offer the possibility of tuning their features through chemical functionalization as well as the presence of an aromatic backbone, which could lead to non-covalent interactions with different nanostructures or aromatic molecules. In this work, a protocol based on ONIOM (QM/QM) calculations to investigate the structural features (binding energies, intermolecular interactions) of flavonols interacting with the surface of several carbon nanostructures (such as graphene, fullerene C60 and carbon nanotubes) is developed. The confinement of flavonols inside carbon nanotubes has also been studied. Three flavonols, galangin, quercetin and myricetin, as well as pristine flavone were selected. Special attention has also been paid to the changes in UV/Vis features of flavonols due to the interaction with carbon nanostructures. Our results point out that π-stacking interactions are the driving force for the adsorption onto carbon nanostructures as well as for the confinement inside carbon nanotubes. Likewise, UV/Vis features of flavonols could be fine-tuned through the interaction with suitable carbon nanostructures.

  10. Optical features of zinc selenide, silver iodide and its two-phase composite nanostructures

    NASA Astrophysics Data System (ADS)

    Smirnov, A. M.; Tomaev, V. V.; Golinskaya, A. D.; Kozlova, M.; Stebakova, J. V.; Valchuk, Y. V.; Borisov, E. N.; Polishchuk, V. A.

    2017-05-01

    The goal of this work is the investigation of optical spectra features of zinc selenide (ZnSe), silver iodide (AgI) and its two-phase composite AgI-ZnSe nanostructures produced by laser ablation method, which can be used to design optical sensors and diffractive structures in integrated optics. Shifted to blue wavelengths relatively to the bulk semiconductor material band edge transmission spectra minima have been discovered for the ZnSe and AgI-ZnSe films. The observed minima of the transmission spectra are peculiar to the quantum energy spectra of semiconductor nanostructures. Discovered transmission spectra minima for the ZnSe and AgI-ZnSe films shifted to the short-wavelength region from the energy of the bulk material band gap can be the evidence of nanocrystals formation during the film growth by laser ablation, and which are characterized by the energy spectrum quantization and lower electron and upper hole quantum confinement levels shifts from the bottom of the conduction and the top valence bands, respectively.

  11. Nanostructured proton conductors formed via in situ polymerization of ionic liquid crystals.

    PubMed

    Lu, Fei; Gao, Xinpei; Dong, Bin; Sun, Panpan; Sun, Nan; Xie, Shuting; Zheng, Liqiang

    2014-12-24

    Ionic liquid crystals (ILCs) with hexagonal and lamellar phases were successfully fabricated by the self-assembly of a polymerizable amphiphilic zwitterion, which is formed by 3-(1-vinyl-3-imidazolio)propanesulfonate (VIPS) and 4-dodecyl benzenesulfonic acid (DBSA) based on intermolecular electrostatic interactions. The microstructures and phase behaviors of ILCs were studied by polarized microscope (POM) and small-angle X-ray scattering (SAXS). The ILC topological structures can be considered as proton pathways and further fixed by photopolymerization to prepare nanostructured proton-conductive films. The introduction of highly ordered and well-defined ILC structures into these polymeric films radically improves the ionic conductivities.

  12. Electrolyte composition dependence of the morphological and nanostructural features of porous silicon prepared by electrochemical anodic etching

    NASA Astrophysics Data System (ADS)

    Kim, Hyo-Han; Son, Jong-Ick; Yun, Han-Sol; Cho, Nam-Hee

    2014-11-01

    Porous silicon layers were formed by electrochemical anodic etching of p-type Si wafers. The electrostatic condition at the interface between the Si wafers and electrolytes was affected sensitively by the addition of isopropyl alcohol (IPA) in the etchant. As the IPA ratio was varied in the range of 0 to 75%, the ideality factor in the ln I-V relationships and the viscosity of the electrolytes changed from 27.2 to 16.0, and from 1.0 to 3.3 cp, respectively. The etched surface exhibited three different morphologies, such as `turtle-back'-, `column'-, and `mountain'-like structures depending on the electrolyte composition. The etched layers contained Si nanocrystallites, 5.5 to 2.6 nm in size, which exhibited photoluminescence features in the wavelength range, 733 to 624 nm. The variation of the band gap was determined by size of the nanocrystallites, whereas the nanostructural and morphological features were dependent on the IPA ratios of the etchants.

  13. Application of porous alumina formed in selenic acid solution for nanostructures investigation via Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Nazarkina, Y. V.; Gavrilov, S. A.; Polohin, A. A.; Gromov, D.; Shaman, Y. P.

    2016-12-01

    Applicability of porous anodic alumina formed in selenic acid based electrolyte as the matrix for formation and Raman characterization of nanomaterials is investigated. For that, Raman spectra of nanostructured CdS layers deposited on top of porous alumina matrices are obtained. These spectra were compared with the ones, registered for the composites prepared using the commonly used matrix formed in oxalic acid solution. It is shown that application of porous alumina matrix formed in selenic acid electrolyte afford to detect the peaks corresponding to the CdS layers even at small amounts of CdS. It happens due to the absence of luminescence background in such matrix, which exists in matrices produced in organic acid electrolytes, for example, in oxalic acid.

  14. Nanostructure and Composition of Tribo-Boundary Films Formed in Ionic Liquid Lubrication

    SciTech Connect

    Qu, Jun; Chi, Miaofang; Meyer III, Harry M; Blau, Peter Julian; Dai, Sheng; Luo, Huimin

    2011-01-01

    Since the idea of using ionic liquids (ILs) as lubricants was raised in 2001, many studies have been conducted in this area and results have demonstrated superior lubricating performance for a variety of ionic liquids. It is widely believed that tribochemical reactions occur between the metal surface and the IL during the wear process to form a protective tribo-boundary film on the contact area that reduces friction and wear. However, the study of this critical boundary film has been limited to top surface two-dimensional topography examination and chemical analysis in the literature. A more comprehensive characterization is needed to help understand the film formation process and the lubricating mechanism. This study demonstrated a multi-technique three-dimensional approach to characterize the IL-formed boundary films, including top surface morphology examination, cross section nanostructure characterization, and layered chemical analysis. Characterization was carried out on both ferrous and aluminum surfaces lubricated by an ammonium IL. The focused-ion-beam (FIB) technique enabled TEM/EDS examination on the cross section of the boundary film to provide direct measurement of the film thickness, visualization of the nanostructure, and analysis of composition. In addition, composition-depth profiles were generated using XPS aided by ion-sputtering to reveal the composition change at different levels of the boundary film to investigate the film formation process.

  15. Spray-Formed Tooling with Micro-Scale Features

    SciTech Connect

    Kevin McHugh

    2010-06-01

    Molds, dies, and related tooling are used to shape many of the plastic and metal components we use every day at home and work. Traditional mold-making practices are labor and capital equipment intensive, involving multiple machining, benching and heat treatment operations. Spray forming is an alternative method to manufacture molds and dies. The general concept is to atomize and deposit droplets of a tooling alloy onto a pattern to form a thick deposit while imaging the pattern’s shape, surface texture and details. Unlike conventional machining, this approach can be used to fabricate tooling with micro-scale surface features. This paper describes a research effort to spray form molds and dies that are used to image micro-scale surface textures into polymers. The goal of the study is to replicate textures that give rise to superhydrophobic behavior by mimicking the surface structure of highly water repellent biological materials such as the lotus leaf. Spray conditions leading to high transfer fidelity of features into the surface of molded polymers will be described. Improvements in water repellency of these materials was quantified by measuring the static contact angle of water droplets on flat and textured surfaces.

  16. The role of nanoscale defect features in enhancing the thermoelectric performance of p-type nanostructured SiGe alloys

    NASA Astrophysics Data System (ADS)

    Bathula, Sivaiah; Jayasimhadri, M.; Gahtori, Bhasker; Singh, Niraj Kumar; Tyagi, Kriti; Srivastava, A. K.; Dhar, Ajay

    2015-07-01

    Despite SiGe being one of the most widely studied thermoelectric materials owing to its application in radioisotope thermoelectric generators (RTG), the thermoelectric figure-of merit (ZT) of p-type SiGe is still quite low, resulting in poor device efficiencies. In the present study, we report a substantial enhancement in ZT ~ 1.2 at 900 °C for p-type nanostructured Si80Ge20 alloys by creating several types of defect features within the Si80Ge20 nanostructured matrix in a spectrum of nano to meso-scale dimensions during its nanostructuring, by employing mechanical alloying followed by spark plasma sintering. This enhancement in ZT, which is ~25% over the existing state-of-the-art value for a p-type nanostructured Si80Ge20 alloy, is primarily due to its ultralow thermal conductivity of ~2.04 W m-1 K-1 at 900 °C, resulting from the scattering of low-to-high wavelength heat-carrying phonons by different types of defect features in a range of nano to meso-scale dimensions in the Si80Ge20 nanostructured matrix. These include point defects, dislocations, isolated amorphous regions, nano-scale grain boundaries and more importantly, the nano to meso-scale residual porosity distributed throughout the Si80Ge20 matrix. These nanoscale multi-dimensional defect features have been characterized by employing scanning and transmission electron microscopy and correlated with the electrical and thermal transport properties, based on which the enhancement of ZT has been discussed.Despite SiGe being one of the most widely studied thermoelectric materials owing to its application in radioisotope thermoelectric generators (RTG), the thermoelectric figure-of merit (ZT) of p-type SiGe is still quite low, resulting in poor device efficiencies. In the present study, we report a substantial enhancement in ZT ~ 1.2 at 900 °C for p-type nanostructured Si80Ge20 alloys by creating several types of defect features within the Si80Ge20 nanostructured matrix in a spectrum of nano to meso

  17. The role of nanoscale defect features in enhancing the thermoelectric performance of p-type nanostructured SiGe alloys.

    PubMed

    Bathula, Sivaiah; Jayasimhadri, M; Gahtori, Bhasker; Singh, Niraj Kumar; Tyagi, Kriti; Srivastava, A K; Dhar, Ajay

    2015-08-07

    Despite SiGe being one of the most widely studied thermoelectric materials owing to its application in radioisotope thermoelectric generators (RTG), the thermoelectric figure-of merit (ZT) of p-type SiGe is still quite low, resulting in poor device efficiencies. In the present study, we report a substantial enhancement in ZT∼ 1.2 at 900 °C for p-type nanostructured Si80Ge20 alloys by creating several types of defect features within the Si80Ge20 nanostructured matrix in a spectrum of nano to meso-scale dimensions during its nanostructuring, by employing mechanical alloying followed by spark plasma sintering. This enhancement in ZT, which is ∼25% over the existing state-of-the-art value for a p-type nanostructured Si80Ge20 alloy, is primarily due to its ultralow thermal conductivity of ∼2.04 W m(-1) K(-1) at 900 °C, resulting from the scattering of low-to-high wavelength heat-carrying phonons by different types of defect features in a range of nano to meso-scale dimensions in the Si80Ge20 nanostructured matrix. These include point defects, dislocations, isolated amorphous regions, nano-scale grain boundaries and more importantly, the nano to meso-scale residual porosity distributed throughout the Si80Ge20 matrix. These nanoscale multi-dimensional defect features have been characterized by employing scanning and transmission electron microscopy and correlated with the electrical and thermal transport properties, based on which the enhancement of ZT has been discussed.

  18. Endothelial and vascular smooth muscle cell function on poly(lactic-co-glycolic acid) with nano-structured surface features.

    PubMed

    Miller, Derick C; Thapa, Anil; Haberstroh, Karen M; Webster, Thomas J

    2004-01-01

    Biomaterials that successfully integrate into surrounding tissue should match not only the tissue's mechanical properties, but also its topography. The cellular response to a biomaterial may be enhanced in synthetic polymer formulations by mimicking the surface roughness created by the associated nano-structured extra-cellular matrix components of natural tissue. As a first step towards this endeavor, the goal of the present in vitro study was to use these design parameters to develop a synthetic, nano-structured, polymeric biomaterial that promotes cell adhesion and growth for vascular applications. In a novel manner, poly(lactic-co-glycolic acid) (PLGA) (50/50wt% mix) was synthesized to possess a range (from micron to nanometer) of surface features. Reduction of surface features was accomplished by treating conventional PLGA with various concentrations of NaOH for select periods of time. Results from cell experiments indicated that, compared to conventional PLGA, NaOH treated PLGA enhanced vascular smooth muscle cell adhesion and proliferation. However, PLGA prepared by soaking in NaOH decreased endothelial cell adhesion and proliferation compared to conventional PLGA. After further investigation, this finding was determined to be a result of chemical (and not topographical) changes during polymer synthesis. Surface chemistry effects were removed while retaining nano-structured topography by using polymer/elastomer casting methods. Results demonstrated that endothelial and smooth muscle cell densities increased on nano-structured cast PLGA. For these reasons, the present in vitro study provided the first evidence that nano-structured surface features can significantly improve vascular cell densities; such design criteria can be used in the synthesis of the next-generation of more successful tissue-engineered vascular grafts.

  19. Promising features of low-temperature grown Ge nanostructures on Si(001) substrates

    NASA Astrophysics Data System (ADS)

    Wang, Ze; Wang, Shuguang; Yin, Yefei; Liu, Tao; Lin, Dongdong; Li, De-hui; Yang, Xinju; Jiang, Zuimin; Zhong, Zhenyang

    2017-03-01

    High-quality Ge nanostructures are obtained by molecular beam epitaxy of Ge on Si(001) substrates at 200 °C and ex situ annealing at 400 °C. Their structural properties are comprehensively characterized by atomic force microscopy, transmission electron microscopy and Raman spectroscopy. It is disclosed that they are almost defect free except for some defects at the Ge/Si interface and in the subsequent Si capping layer. The misfit strain in the nanostructure is substantially relaxed. Dramatically strong photoluminescence (PL) from the Ge nanostructures is observed. Detailed analyses on the power- and temperature-dependent PL spectra, together with a self-consistent calculation, indicate the confinement and the high quantum efficiency of excitons within the Ge nanostructures. Our results demonstrate that the Ge nanostructures obtained via the present feasible route may have great potential in optoelectronic devices for monolithic optical–electronic integration circuits.

  20. Promising features of low-temperature grown Ge nanostructures on Si(001) substrates.

    PubMed

    Wang, Ze; Wang, Shuguang; Yin, Yefei; Liu, Tao; Lin, Dongdong; Li, De-Hui; Yang, Xinju; Jiang, Zuimin; Zhong, Zhenyang

    2017-03-17

    High-quality Ge nanostructures are obtained by molecular beam epitaxy of Ge on Si(001) substrates at 200 °C and ex situ annealing at 400 °C. Their structural properties are comprehensively characterized by atomic force microscopy, transmission electron microscopy and Raman spectroscopy. It is disclosed that they are almost defect free except for some defects at the Ge/Si interface and in the subsequent Si capping layer. The misfit strain in the nanostructure is substantially relaxed. Dramatically strong photoluminescence (PL) from the Ge nanostructures is observed. Detailed analyses on the power- and temperature-dependent PL spectra, together with a self-consistent calculation, indicate the confinement and the high quantum efficiency of excitons within the Ge nanostructures. Our results demonstrate that the Ge nanostructures obtained via the present feasible route may have great potential in optoelectronic devices for monolithic optical-electronic integration circuits.

  1. Nanostructures formed by displacement of porous silicon with copper: from nanoparticles to porous membranes

    PubMed Central

    2012-01-01

    The application of porous silicon as a template for the fabrication of nanosized copper objects is reported. Three different types of nanostructures were formed by displacement deposition of copper on porous silicon from hydrofluoric acid-based solutions of copper sulphate: (1) copper nanoparticles, (2) quasi-continuous copper films, and (3) free porous copper membranes. Managing the parameters of porous silicon (pore sizes, porosity), deposition time, and wettability of the copper sulphate solution has allowed to achieve such variety of the copper structures. Elemental and structural analyses of the obtained structures are presented. Young modulus measurements of the porous copper membrane have been carried out and its modest activity in surface enhanced Raman spectroscopy is declared. PMID:22916840

  2. Unique nanostructural features in Fe, Mn-doped YBCO thin films

    NASA Astrophysics Data System (ADS)

    Meledin, A.; Turner, S.; Cayado, P.; Mundet, B.; Solano, E.; Ricart, S.; Ros, J.; Puig, T.; Obradors, X.; Van Tendeloo, G.

    2016-12-01

    An attempt to grow a thin epitaxial composite film of YBa2Cu3O7-δ (YBCO) with spinel MnFe2O4 (MFO) nanoparticles on a LAO substrate using the CSD approach resulted in a decomposition of the spinel and various doping modes of YBCO with the Fe and Mn cations. These nanostructural effects lead to a lowering of T c and a slight J c increase in field. Using a combination of advanced transmission electron microscopy (TEM) techniques such as atomic resolution high-angle annular dark field scanning TEM, energy dispersive x-ray spectroscopy and electron energy-loss spectroscopy we have been able to decipher and characterize the effects of the Fe and Mn doping on the film architecture. The YBaCuFeO5 anion-deficient double perovskite phase was detected in the form of 3D inclusions as well as epitaxially grown lamellas within the YBCO matrix. These nano-inclusions play a positive role as pinning centers responsible for the J c/J sf (H) dependency smoothening at high magnetic fields in the YBCO-MFO films with respect to the pristine YBCO films.

  3. Nanostructure characterisation of flow-formed Cr-Mo-V steel using transmission Kikuchi diffraction technique.

    PubMed

    Birosca, S; Ding, R; Ooi, S; Buckingham, R; Coleman, C; Dicks, K

    2015-06-01

    Nowadays flow-forming has become a desired near net shape manufacturing method as it provides excellent mechanical properties with improved surface finish and significant manufacturing cost reduction. However, the material is subjected to excessive plastic deformation during flow-forming process, generating a very fine and complex microstructure. In addition, the intense dislocation density and residual stress that is generated in the component during processing makes the microstructure characterisation using conventional micro-analytical tools challenging. Thus, the microstructure/property relationship study in such a material is rather difficult. In the present study a flow-formed Cr-Mo-V steel nanostructure and crystallographic texture were characterised by means of Transmission Kikuchi Diffraction (TKD). Here, TKD is shown to be a powerful technique in revealing very fine martensite laths within an austenite matrix. Moreover, fine precipitates in the order of 20-70 nm on the martensite lath boundaries were clearly imaged and characterised. This greatly assisted in understanding the preferable site formation of the carbides in such a complex microstructure. The results showed that the actual TKD spatial resolution was in the range of 5-10 nm using 25 kV for flow-formed Cr-Mo-V steel.

  4. Flexible a-Si:H Solar Cells with Spontaneously Formed Parabolic Nanostructures on a Hexagonal-Pyramid Reflector.

    PubMed

    Dong, Wan Jae; Yoo, Chul Jong; Cho, Hyoung Won; Kim, Kyoung-Bo; Kim, Moojin; Lee, Jong-Lam

    2015-04-24

    Flexible amorphous silicon (a-Si:H) solar cells with high photoconversion efficiency (PCE) are demonstrated by embedding hexagonal pyramid nanostructures below a Ag/indium tin oxide (ITO) reflector. The nanostructures constructed by nanoimprint lithography using soft materials allow the top ITO electrode to spontaneously form parabolic nanostructures. Nanoimprint lithography using soft materials is simple, and is conducted at low temperature. The resulting structure has excellent durability under repeated bending, and thus, flexible nanostructures are successfully constructed on flexible a-Si:H solar cells on plastic film. The nanoimprinted pyramid back reflector provides a high angular light scattering with haze reflectance >98% throughout the visible spectrum. The spontaneously formed parabolic nanostructure on the top surface of the a-Si:H solar cells both reduces reflection and scatters incident light into the absorber layer, thereby elongating the optical path length. As a result, the nanopatterned a-Si:H solar cells, fabricated on polyethersulfone (PES) film, exhibit excellent mechanical flexibility and PCE increased by 48% compared with devices on a flat substrate.

  5. Superhydrophilic nanostructure

    DOEpatents

    Mao, Samuel S; Zormpa, Vasileia; Chen, Xiaobo

    2015-05-12

    An embodiment of a superhydrophilic nanostructure includes nanoparticles. The nanoparticles are formed into porous clusters. The porous clusters are formed into aggregate clusters. An embodiment of an article of manufacture includes the superhydrophilic nanostructure on a substrate. An embodiment of a method of fabricating a superhydrophilic nanostructure includes applying a solution that includes nanoparticles to a substrate. The substrate is heated to form aggregate clusters of porous clusters of the nanoparticles.

  6. Diagnostic features of relief formations on the nanostructured titanium VT1-0 surface after laser shock-wave treatment

    NASA Astrophysics Data System (ADS)

    Lytvynenko, I. V.; Lupenko, S. A.; Maruschak, P. O.; Panin, S. V.; Hats, Yu I.

    2017-02-01

    A new class of diagnostic features for conducting morphological analysis of relief formations induced by laser shock-wave treatment on the surface of the nanostructured titanium VT1-0 alloy is proposed. They are the coefficients of series expansions of statistical estimates for the orthogonal basis of Chebyshev, Laguerre, Kravchuk discrete polynomials and trigonometric functions. Based on the criterion of the minimum number of the diagnostic features in the above-mentioned bases, the Chebyshev one was selected as the most appropriate to solve this problem.

  7. Feature Article: Fast scanning tunnelling microscopy as a tool to understand changes on metal surfaces: from nanostructures to single atoms

    NASA Astrophysics Data System (ADS)

    Morgenstern, Karina

    2005-03-01

    The Feature Article [1] describes how structural changes in metallic nanostructures can be followed with fast scanning tunneling microscopy (STM). The title page shows the same spot of a Ag(111) surface at room temperature, imaged with STM approximately one hour apart. Intrinsic changes to prepared nano-structures are marked as Brownian motion of vacancy islands (rectangle), coalescence of two vacancy islands (hexagon), and decay of an adatom island (circle).Karina Morgenstern is now professor at the University of Hannover. Her research is placed within the field of nanoscience and is in particular devoted to thermally activated processes of metallic nanostructures, electronically activated reactions of molecules on metallic surfaces, and water-metal interactions.The present issue of physica status solidi (b) also contains the article Apperance of copper d9 defect centres in wide-gap CdSe nanoparticles: A high-fequency EPR study by N. R. J. Poolton et al. as Editor's Choice [2] as well as several papers on electrical and nonlinear optical properties from the European Conference on Organised Films (ECOF 2004) chaired by José Antonio de Saja, Valladolid.

  8. Characterization of the nanostructure of complexes formed by single- or double-stranded oligonucleotides with a cationic surfactant.

    PubMed

    Liu, Xiaoyang; Abbott, Nicholas L

    2010-12-02

    We report the use of dynamic light scattering (DLS), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS) to characterize the nanostructure of complexes formed by either single- or double-stranded oligonucleotides with a cationic surfactant (cetyltrimethylammonium bromide, CTAB) in aqueous solution (1 mM Li(2)SO(4)). For single-stranded oligonucleotides 5'-A(20)-3' and 5'-CCCCATTCTAGCAGCCCGGG-3', both the appearance of two Bragg peaks (at 0.14 and 0.28 Å(-1)) in SAXS spectra with a spacing of 1:2 and form factor fits to SANS spectra are consistent with the presence of multilamellar vesicles (with, on average, 6-9 layers with a periodicity of 45-48 Å). Some samples showed evidence of an additional Bragg peak (at 0.20 Å(-1)) associated with periodic packing (with a periodicity of 31 Å) of the oligonucleotides within the lamellae of the nanostructure. The nucleotide composition of the single-stranded oligonucleotides was also found to impact the number and size of the complexes formed with CTAB. In contrast to 5'-A(20)-3' and 5'-CCCCATTCTAGCAGCCCGGG-3', 5'-T(20)-3' did not change the state of aggregation of CTAB (globular micelles) over a wide range of oligonucleotide:CTAB charge ratios. These results support the proposition that hydrophobic interactions, as well as electrostatics, play a central role in the formation of complexes between cationic amphiphiles and single-stranded oligonucleotides and thus give rise to nanostructures that depend on nucleotide composition. In contrast to the single-stranded oligonucleotides, for double-stranded oligonucleotides mixed with CTAB, three Bragg peaks (0.13, 0.23, and 0.25 Å(-1)) in SAXS spectra with a spacing ratio of 1:√3:√4 and characteristic changes in SANS spectra indicate formation of a hexagonal nanostructure. Also, the composition of the double-stranded oligonucleotides did not measurably impact the nanostructure of complexes formed with CTAB, suggesting that electrostatic

  9. Form and content: looking at visual features of television.

    PubMed

    Schmitt, K L; Anderson, D R; Collins, P A

    1999-07-01

    Television viewing at home by 50 individuals in 5 age groups (2-, 5-, 8-, 12-year-olds, and adults) was recorded on 1-s time-lapse videotapes over 10-day periods. Coding was based on 5-min point samples. Analysis examined looking at the TV screen in relation to the visual presence of the features cuts, movement, animation, man, woman, child, and nonhuman; content features were child vs. adult programming and overt purposeful character behavior. Cuts, movement, and overt purposeful character behavior were positively related to looking independent of child vs. adult programming. Associations with looking for the remaining features depended on the viewer's age or sex or type of content within which they occurred.

  10. Role of artesian groundwater in forming Martian permafrost features

    NASA Technical Reports Server (NTRS)

    Howard, Alan D.

    1991-01-01

    Various landforms possibly related to formation (growth), movement, or decay of ground ice have been identified on Mars, including fretted terrain (ft) and associated lobate debris aprons (lda), the chaotic terrain, concentric crater fills (ccf), polygonal ground, softened terrain, small domes that are possibly pingos, and curvilinear (fingerprint) features (cuf). Glaciers may also have been present. Some of these may involve ice derived from artesian groundwater. Topical areas of discussion are: Mars groundwater and the location of permafrost features; the ft, lda, ccf, and cuf; role of artesian groundwater in formation of fretted terrain, lobate debris blankets, and concentric crater fills; sources of glacial ice; and pingos and other pseudovolcanic structures.

  11. Nanostructured BN-Mg composites: features of interface bonding and mechanical properties.

    PubMed

    Kvashnin, Dmitry G; Krasheninnikov, Arkady V; Shtansky, Dmitry; Sorokin, Pavel B; Golberg, Dmitri

    2016-01-14

    Magnesium (Mg) is one of the lightest industrially used metals. However, wide applications of Mg-based components require a substantial enhancement of their mechanical characteristics. This can be achieved by introducing small particles or fibers into the metal matrix. Using first-principles calculations, we investigate the stability and mechanical properties of a nanocomposite made of magnesium reinforced with boron nitride (BN) nanostructures (BN nanotubes and BN monolayers). We show that boron vacancies at the BN/Mg interface lead to a substantial increase in BN/Mg bonding establishing an efficient route towards the development of BN/Mg composite materials with enhanced mechanical properties.

  12. [Epidemiologic features of tetanus in adults form Yucatan, Mexico].

    PubMed

    Durán-Nah, J; Ceh-Gómez, E; Díaz-Cervera, I; Mis-Fernández, R

    2001-01-01

    To describe epidemiologic features from tetanus in adult patients (TIAP) treated at hospital general O'Horan in Merida, Yucatan, Mexico and compare them with another Mexican series analyzed 25 years ago. From 1985 to 1999, 121 TIAP cases aged 13 years or older were identified from which 112 were analyzed. Diagnosis of TIAP was made just in a clinical basis. To analyze information inferencial statistics were used. People affected by tetanus averaged 43 +/- 21, 95% CI 39 to 47. A 3:1 male to female ratio was documented. Eighty two (73%) patients come from the rural area; 43 (38%) did work as peasants. Sixty two cases (55%) were diagnosed during the Fall and Winter seasons. In 91 patients (81%) no anti-tetanus vaccination was documented. In 89 cases (79%) incubation period averaged 5.4 +/- 4 days, 95% CI 5 to 6. According to this 89 cases (79%) with incubation period < 10 days were graded as severe tetanus and 23 (21%) with incubation period > or = 10 days were graded as non-severe tetanus. Tetanus-prone wounds were documented in 95 (85%) cases, 59 (62%) of which (62%) were localized in the lower extremities. Final outcome dichotomized either as death patient (group one) or surviving patient (group two) was documented in 103 cases of whom 67 (65%) were in group one and 36 (35%) were in group two. By comparing them, differences were seen in mean age (P = 0.004, 95% CI 3.9 to 19.8), age categories (< 50 vs. > or = 50) (chi 2 P = 0.001, 95% CI 0.6 to 0.60), severity of tetanus (Fisher exact test P = 0.0009, 95% CI 2 to 53) and mean hospitalization time (mean difference 14.8, P = 0.0001, 95% CI 11 to 18) but not in sex (chi 2 0.69, P = 0.40). In the State of Yucatan, Peninsula de Yucatan, Mexico, TIAP is still an endemic process with high mortality rate specially among young productive people. Secondary preventive measures as routinely tetanus toxoid booster vaccination are still not enough, at least in adulthood.

  13. Morphological and biochemical features of Borrelia burgdorferi pleomorphic forms.

    PubMed

    Meriläinen, Leena; Herranen, Anni; Schwarzbach, Armin; Gilbert, Leona

    2015-03-01

    The spirochaete bacterium Borrelia burgdorferi sensu lato is the causative agent of Lyme disease, the most common tick-borne infection in the northern hemisphere. There is a long-standing debate regarding the role of pleomorphic forms in Lyme disease pathogenesis, while very little is known about the characteristics of these morphological variants. Here, we present a comprehensive analysis of B. burgdorferi pleomorphic formation in different culturing conditions at physiological temperature. Interestingly, human serum induced the bacterium to change its morphology to round bodies (RBs). In addition, biofilm-like colonies in suspension were found to be part of B. burgdorferi's normal in vitro growth. Further studies provided evidence that spherical RBs had an intact and flexible cell envelope, demonstrating that they are not cell wall deficient, or degenerative as previously implied. However, the RBs displayed lower metabolic activity compared with spirochaetes. Furthermore, our results indicated that the different pleomorphic variants were distinguishable by having unique biochemical signatures. Consequently, pleomorphic B. burgdorferi should be taken into consideration as being clinically relevant and influence the development of novel diagnostics and treatment protocols.

  14. Morphological and biochemical features of Borrelia burgdorferi pleomorphic forms

    PubMed Central

    Herranen, Anni; Schwarzbach, Armin; Gilbert, Leona

    2015-01-01

    The spirochaete bacterium Borrelia burgdorferi sensu lato is the causative agent of Lyme disease, the most common tick-borne infection in the northern hemisphere. There is a long-standing debate regarding the role of pleomorphic forms in Lyme disease pathogenesis, while very little is known about the characteristics of these morphological variants. Here, we present a comprehensive analysis of B. burgdorferi pleomorphic formation in different culturing conditions at physiological temperature. Interestingly, human serum induced the bacterium to change its morphology to round bodies (RBs). In addition, biofilm-like colonies in suspension were found to be part of B. burgdorferi’s normal in vitro growth. Further studies provided evidence that spherical RBs had an intact and flexible cell envelope, demonstrating that they are not cell wall deficient, or degenerative as previously implied. However, the RBs displayed lower metabolic activity compared with spirochaetes. Furthermore, our results indicated that the different pleomorphic variants were distinguishable by having unique biochemical signatures. Consequently, pleomorphic B. burgdorferi should be taken into consideration as being clinically relevant and influence the development of novel diagnostics and treatment protocols. PMID:25564498

  15. Largely Enhanced Single-molecule Fluorescence in Plasmonic Nanogaps formed by Hybrid Silver Nanostructures

    PubMed Central

    Zhang, Jian; Lakowicz, Joseph R.

    2013-01-01

    It has been suggested that narrow gaps between metallic nanostructures can be practical for producing large field enhancement. We design a hybrid silver nanostructure geometry in which fluorescent emitters are sandwiched between silver nanoparticles and silver island film (SIF). A desired number of polyelectrolyte layers are deposited on the SIF surface before the self-assembly of a second silver nanoparticle layer. Layer-by-layer configuration provides a well-defined dye position. It allows us to study the photophyical behaviors of fluorophores in the resulting gap at the single molecule level. The enhancement factor of a fluorophore located in the gap is much higher than those on silver surfaces alone and on glass. These effects may be used for increased detectability of single molecules bound to surfaces which contain metallic structures for either biophysical studies or high sensitivity assays. PMID:23373787

  16. [Featuring pathogenicity factors in biofilm-forming and no-biofilm forming strains of Staphylococcus epidermidis].

    PubMed

    Sidashenko, O I; Voronkova, O S; Sirokvasha, O A; Vinnikov, A I

    2015-01-01

    A comparative study of the manifestation of pathogenicity factors: hemolytic, lipase, letsytinase activity and ability to adhere in 20 film-forming and 17 non-film-forming strains of S. epidermidis. Studying pathogenicity factors of the film-forming strains it was found that complete hemolysis and lipase activity shown was by all the film-forming strains of S. epidermidis, letsytinase activity was observed in 80%. Among the non-film-forming strains complete hemolysis and lipase activity were observed in 89% and letsytinase - 71%. Researched non-film-forming and film-forming strains of S. epidermidis showed the ability to adhere to buccal epithelial cells of humans. Found that all the film-forming strains of S. epidermidis were hight level adgesion, the highest IAM was equal to 11,84. It was found that among non-film-forming strains of S. epidermidis were low-, medium- and hight level adgesion. IAM of non-film-forming strains of S. epidermidis is 3 times lower compared to the IAM of the film-forming strains of human epithelial cells and was 3.2.

  17. The In Vivo Bone Response of Ultraviolet-Irradiated Titanium Implants Modified with Spontaneously Formed Nanostructures: An Experimental Study in Rabbits.

    PubMed

    Shen, Jianwei; Liu, Jianhu; Chen, Xiaoyi; Wang, Xiaoxiang; He, Fuming; Wang, Huiming

    2016-01-01

    Acid etching in conjunction with storage in an aqueous solution can induce nanostructures forming spontaneously on titanium surfaces, but an inevitable biologic degradation is suspected to accompany the evolution of nanostructures. The aim of this study was to investigate whether ultraviolet (UV) irradiation is effective to solve this problem and further enhance the bioactivity. Surface characteristics of five groups of titanium implants (SLAnew, SLAold, modSLA, UV-SLA, and UV-modSLA) and their in vivo bone response were analyzed in this study. The surface characteristics were evaluated with contact angle measurements, scanning electron microscopy, and x-ray photon spectroscopy. A total of 160 implants (32 for each group) were inserted into the tibial metaphyses and femoral condyles of 40 rabbits. After 3 and 6 weeks, the rabbits were euthanized for removal torque tests and histomorphometric analysis. Spontaneously formed nanostructures were observed on water-stored surfaces with a size of approximately 15 nm in diameter, and an inevitable contamination of hydrocarbons accompanied the evolution of nanostructures. UV irradiation effectively eliminated hydrocarbon contamination that accompanied nanostructure evolution. UV-modSLA implants showed the highest removal torque value, and UV-irradiated implants exhibited higher bone-to-implant contact and bone area. UV irradiation can effectively eliminate the hydrocarbon contamination accompanying the evolution of nanostructures and further enhance the osseointegration. Nanostructures and UV treatment have combined effects in enhancing the interfacial strength between titanium and bone, while UV photofunctionalization has much more overwhelming effects on histologic and histomorphometric performance.

  18. Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

    SciTech Connect

    Wirth, B D; Asoka-Kumar, P; Howell, R H; Odette, G R; Sterne, P A

    2001-01-01

    Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs and VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime ({approx}500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs.

  19. Nanostructured ZnO films in forms of rod, plate and flower: Electrodeposition mechanisms and characterization

    NASA Astrophysics Data System (ADS)

    Kıcır, Nur; Tüken, Tunç; Erken, Ozge; Gumus, Cebrail; Ufuktepe, Yuksel

    2016-07-01

    Uniformity and reproducibility of well-defined ZnO nanostructures are particularly important issues for fabrication and applications of these nanomaterials. In present study, we report selective morphology control during electrodeposition, by adjusting the hydroxyl generation rate and Zn(OH)2 deposition. In presence of remarkably high chloride concentration (0.3 M) and -1.0 V deposition potential, slow precipitation conditions were provided in 5 mM Zn(NO3)2 solution. By doing so, we have obtained highly ordered, vertically aligned and uniformly spaced hexagon shaped nanoplates, on ITO surface. We have also investigated the mechanism for shifting the morphology from rod/plate to flower like structure of ZnO, for better understanding the reproducibility. For this reason, the influence of various supporting electrolytes (sodium/ammonium salts of acetate) has been investigated for interpretation of the influence of OH- concentration nearby the surface. From rod to plate and flower nanostructures, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were realized for characterization, also the optical properties were studied.

  20. Unfolding a molecular trefoil derived from a zwitterionic metallopeptide to form self-assembled nanostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Ye; Zhou, Ning; Shi, Junfeng; Pochapsky, Susan Sondej; Pochapsky, Thomas C.; Zhang, Bei; Zhang, Xixiang; Xu, Bing

    2015-02-01

    While used extensively by nature to control the geometry of protein structures, and dynamics of proteins, such as self-organization, hydration forces and ionic interactions received less attention for controlling the behaviour of small molecules. Here we describe the synthesis and characterization of a novel zwitterionic metallopeptide consisting of a cationic core and three distal anionic groups linked by self-assembling peptide motifs. 2D NMR spectra, total correlated spectroscopy and nuclear Overhauser effect spectroscopy, show that the molecule exhibits a three-fold rotational symmetry and adopts a folded conformation in dimethyl sulfoxide due to Coulombic forces. When hydrated in water, the molecule unfolds to act as a self-assembling building block of supramolecular nanostructures. By combining ionic interactions with the unique geometry from metal complex and hydrophobic interactions from simple peptides, we demonstrate a new and effective way to design molecules for smart materials through mimicking a sophisticated biofunctional system using a conformational switch.

  1. Unfolding a molecular trefoil derived from a zwitterionic metallopeptide to form self-assembled nanostructures.

    PubMed

    Zhang, Ye; Zhou, Ning; Shi, Junfeng; Pochapsky, Susan Sondej; Pochapsky, Thomas C; Zhang, Bei; Zhang, Xixiang; Xu, Bing

    2015-02-19

    While used extensively by nature to control the geometry of protein structures, and dynamics of proteins, such as self-organization, hydration forces and ionic interactions received less attention for controlling the behaviour of small molecules. Here we describe the synthesis and characterization of a novel zwitterionic metallopeptide consisting of a cationic core and three distal anionic groups linked by self-assembling peptide motifs. 2D NMR spectra, total correlated spectroscopy and nuclear Overhauser effect spectroscopy, show that the molecule exhibits a three-fold rotational symmetry and adopts a folded conformation in dimethyl sulfoxide due to Coulombic forces. When hydrated in water, the molecule unfolds to act as a self-assembling building block of supramolecular nanostructures. By combining ionic interactions with the unique geometry from metal complex and hydrophobic interactions from simple peptides, we demonstrate a new and effective way to design molecules for smart materials through mimicking a sophisticated biofunctional system using a conformational switch.

  2. Spin-transfer torque and specific features of magnetic-state switching in vacuum tunnel nanostructures

    SciTech Connect

    Demin, G. D. Popkov, A. F.; Dyuzhev, N. A.

    2015-12-15

    The specific features of spin-transfer torque in vacuum tunnel structures with magnetic electrodes are investigated using the quasi-classical Sommerfeld model of electron conductivity, which takes into account the exchange splitting of the spin energy subbands of free electrons. Using the calculated voltage dependences of the transferred torques for a tunnel structure with cobalt electrodes and noncollinear magnetic moments in the electrodes, diagrams of stable spin states on the current–field parameter plane in the in-plane geometry of the initial magnetization are obtained.

  3. Atomically Traceable Nanostructure Fabrication.

    PubMed

    Ballard, Josh B; Dick, Don D; McDonnell, Stephen J; Bischof, Maia; Fu, Joseph; Owen, James H G; Owen, William R; Alexander, Justin D; Jaeger, David L; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J; Wallace, Robert M; Reidy, Richard; Silver, Richard M; Randall, John N; Von Ehr, James

    2015-07-17

    Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

  4. Atomically Traceable Nanostructure Fabrication

    PubMed Central

    Ballard, Josh B.; Dick, Don D.; McDonnell, Stephen J.; Bischof, Maia; Fu, Joseph; Owen, James H. G.; Owen, William R.; Alexander, Justin D.; Jaeger, David L.; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J.; Wallace, Robert M.; Reidy, Richard; Silver, Richard M.; Randall, John N.; Von Ehr, James

    2015-01-01

    Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure. PMID:26274555

  5. Luminescent features of novel sol-gel derived lanthanide multi-doped oxyfluoride nano-structured phosphors for white LED

    NASA Astrophysics Data System (ADS)

    Gouveia-Neto, Artur S.; da Silva, Andréa F.; Bueno, Luciano A.; Costa, Ernande B.

    2011-03-01

    Rare-earth doped oxyfluoride 75SiO2:25PbF2 nano-structured phosphors for white-light-emitting diodes were synthesized by thermal treatment of precursor sol-gel derived glasses. Room temperature luminescence features of Eu3+, Sm3+, Tb3+, Eu3+/Tb3+ and Sm3+/Tb3+ ions incorporated into low-phonon-energy PbF2 nanocrystals dispersed in the aluminosilicate glass matrix and excited with UV(395 nm) and blue(405 nm) light emitting diodes was investigated. The luminescence spectra exhibited strong emission signals in the red(600, 610, 625, 646 nm), green(548, and 560 nm) and blue(485 nm) wavelength regions. White-light emission was observed in Sm/Tb and Eu/Tb double-doped activated phosphors employing UV-LED excitation at 395 nm. The dependence of the luminescence emission intensities upon annealing temperature, and rare-earth concentration was also examined. The results indicated that there exist optimum annealing temperature and activator ion concentration in order to obtain intense visible emission light with high color rendering index. The study suggest that the nanocomposite phosphor based upon 75SiO2:25PbF2 host herein reported is a promising contender for white-light LED applications.

  6. Confirming the key role of Ar+ ion bombardment in growth feature of nanostructured carbon materials by PECVD.

    PubMed

    Liu, Yulin; Lin, Jinghuang; Jia, Henan; Chen, Shulin; Qi, J; Qu, Chaoqun; Cao, Jian; Feng, Jicai; Fei, Weidong

    2017-09-20

    In order to confirm the key role of plasma etching in growth feature of nanostructured carbon materials (NCMs), here we reported a novel strategy to in-situ create different states of plasma etching conditions in plasma enhanced chemical vapor deposition (PECVD) by separating catalyst film from substrate. Different plasma-related environments on either side of the catalyst film were created simultaneously for achieving multi-layered structural NCMs. Results showed that plasma etching is observed crucial and complex for the growth of NCMs. The effect of plasma etching has both positive and negative sides on carbon nanotubes (CNTs). On one hand, plasma etching can break up the structure of CNTs and thus thin CNTs cannot be obtained. On the other hand, plasma etching can remove the redundant carbon on surface of large catalyst particles, contributing to catalyzing thick CNTs. As a result, the diameter of CNTs depends on the state of plasma etching. For vertically oriented few-layer graphene (VFG), plasma etching is an essential asset and strong plasma etching can even change the CNTs into VFG. Therefore, specific multi-layered structural NCMs can be obtained by PECVD combining plasma etching with catalyst separation method, which is promising in many fields. © 2017 IOP Publishing Ltd.

  7. Particulates vs. fibers: dimension featured magnetic and visible light driven photocatalytic properties of Sc modified multiferroic bismuth ferrite nanostructures.

    PubMed

    Sakar, M; Balakumar, S; Saravanan, P; Bharathkumar, S

    2016-01-14

    We report the magnetic and visible light driven photocatalytic properties of scandium (Sc) substituted bismuth ferrite (BSFO) particulate and fiber nanostructures. An increasing concentration of Sc was found to reduce the crystallite size, particle size and band gap energy of the BSFO nanostructures, which was evident from X-ray diffraction, field emission scanning electron microscopy and UV-Visible diffuse reflectance spectroscopy analysis respectively. The temperature dependent magnetic studies carried out using a SQUID magnetometer suggested that the origin of the magnetic properties in the pure BFO system could be the emergence of an antiferromagnetic-core/ferromagnetic-shell like structure, in contrast to the modified spin canted structures in the case of the BSFO nanostructures. The observed photocatalytic efficiency was attributed to the enhanced band bending process and recombination resistance in the BSFO nanostructures. For a comparative study, the photocatalytic activities of some selected compositions were also investigated under simulated solar light along with natural solar light.

  8. Particulates vs. fibers: dimension featured magnetic and visible light driven photocatalytic properties of Sc modified multiferroic bismuth ferrite nanostructures

    NASA Astrophysics Data System (ADS)

    Sakar, M.; Balakumar, S.; Saravanan, P.; Bharathkumar, S.

    2015-12-01

    We report the magnetic and visible light driven photocatalytic properties of scandium (Sc) substituted bismuth ferrite (BSFO) particulate and fiber nanostructures. An increasing concentration of Sc was found to reduce the crystallite size, particle size and band gap energy of the BSFO nanostructures, which was evident from X-ray diffraction, field emission scanning electron microscopy and UV-Visible diffuse reflectance spectroscopy analysis respectively. The temperature dependent magnetic studies carried out using a SQUID magnetometer suggested that the origin of the magnetic properties in the pure BFO system could be the emergence of an antiferromagnetic-core/ferromagnetic-shell like structure, in contrast to the modified spin canted structures in the case of the BSFO nanostructures. The observed photocatalytic efficiency was attributed to the enhanced band bending process and recombination resistance in the BSFO nanostructures. For a comparative study, the photocatalytic activities of some selected compositions were also investigated under simulated solar light along with natural solar light.We report the magnetic and visible light driven photocatalytic properties of scandium (Sc) substituted bismuth ferrite (BSFO) particulate and fiber nanostructures. An increasing concentration of Sc was found to reduce the crystallite size, particle size and band gap energy of the BSFO nanostructures, which was evident from X-ray diffraction, field emission scanning electron microscopy and UV-Visible diffuse reflectance spectroscopy analysis respectively. The temperature dependent magnetic studies carried out using a SQUID magnetometer suggested that the origin of the magnetic properties in the pure BFO system could be the emergence of an antiferromagnetic-core/ferromagnetic-shell like structure, in contrast to the modified spin canted structures in the case of the BSFO nanostructures. The observed photocatalytic efficiency was attributed to the enhanced band bending process

  9. InP nanostructures formed in GaP-based nanowires grown on Si(1 1 1) substrates

    NASA Astrophysics Data System (ADS)

    Tateno, K.; Zhang, G.; Nakano, H.

    2008-06-01

    Two types of InP growth in GaP-based nanowires have been reported. The nanowires were grown by the vapor-liquid-solid method using Au particles of around 20-nm diameter as catalysts. For GaP/InP/GaP nanowire growth, InP egg-like structures were formed when the InP growth temperature was higher than the GaP growth one. Successively, the second GaP nanowire could be grown on these InP structures. Transmission electron microscopy and energy dispersive X-ray spectroscopy analyses indicated that these InP nanostructures were grown in both the axial and radial directions and that the edge of the first GaP nanowires was partly covered with InP, which formed a core-shell structure. For InP capping growth, which was performed after the growth of two-times-alternated GaP/GaAs on GaP nanowires, selective InP growth on the two GaAs parts was confirmed.

  10. Form drag in rivers due to small-scale natural topographic features: 1. Regular sequences

    USGS Publications Warehouse

    Kean, J.W.; Smith, J.D.

    2006-01-01

    Small-scale topographic features are commonly found on the boundaries of natural rivers, streams, and floodplains. A simple method for determining the form drag on these features is presented, and the results of this model are compared to laboratory measurements. The roughness elements are modeled as Gaussian-shaped features defined in terms of three parameters: a protrusion height, H; a streamwise length scale, ??; and a spacing between crests, ??. This shape is shown to be a good approximation to a wide variety of natural topographic bank features. The form drag on an individual roughness element embedded in a series of identical elements is determined using the drag coefficient of the individual element and a reference velocity that includes the effects of roughness elements further upstream. In addition to calculating the drag on each element, the model determines the spatially averaged total stress, skin friction stress, and roughness height of the boundary. The effects of bank roughness on patterns of velocity and boundary shear stress are determined by combining the form drag model with a channel flow model. The combined model shows that drag on small-scale topographic features substantially alters the near-bank flow field. These methods can be used to improve predictions of flow resistance in rivers and to form the basis for fully predictive (no empirically adjusted parameters) channel flow models. They also provide a foundation for calculating the near-bank boundary shear stress fields necessary for determining rates of sediment transport and lateral erosion.

  11. Nanostructures formed by cyclodextrin covered procainamide through supramolecular self assembly--spectral and molecular modeling study.

    PubMed

    Rajendiran, N; Mohandoss, T; Sankaranarayanan, R K

    2015-02-05

    Inclusion complexation behavior of procainamide (PCA) with two cyclodextrins (α-CD and β-CD) were analyzed by absorption, fluorescence, scanning electron microscope (SEM), transmission electron microscope (TEM), Raman image, FT-IR, differential scanning colorimeter (DSC), Powder X ray diffraction (XRD) and (1)H NMR. Blue shift was observed in β-CD whereas no significant spectral shift observed in α-CD. The inclusion complex formation results suggest that water molecules also present in the inside of the CD cavity. The present study revealed that the phenyl ring of the PCA drug is entrapped in the CD cavity. Cyclodextrin studies show that PCA forms 1:2 inclusion complex with α-CD and β-CD. PCA:α-CD complex form nano-sized particles (46 nm) and PCA:β-CD complex form self-assembled to micro-sized tubular structures. The shape-shifting of 2D nanosheets into 1D microtubes by simple rolling mechanism were analysed by micro-Raman and TEM images. Thermodynamic parameters (ΔH, ΔG and ΔS) of inclusion process were determined from semiempirical PM3 calculations.

  12. Karyological features of wild and cultivated forms of myrtle (Myrtus communis, Myrtaceae).

    PubMed

    Serçe, S; Ekbiç, E; Suda, J; Gündüz, K; Kiyga, Y

    2010-03-09

    Myrtle is an evergreen shrub or small tree widespread throughout the Mediterranean region. In Turkey, both cultivated and wild forms, differing in plant and fruit size and fruit composition, can be found. These differences may have resulted from the domestication of the cultivated form over a long period of time. We investigated whether wild and cultivated forms of myrtle differ in karyological features (i.e., number of somatic chromosomes and relative genome size). We sampled two wild forms and six cultivated types of myrtle. All the samples had the same chromosome number (2n = 2x = 22). The results were confirmed by 4',6-diamidino-2-phenylindole (DAPI) flow cytometry. Only negligible variation (approximately 3%) in relative fluorescence intensity was observed among the different myrtle accessions, with wild genotypes having the smallest values. We concluded that despite considerable morphological differentiation, cultivated and wild myrtle genotypes in Turkey have similar karyological features.

  13. Influence of fourfold anisotropy form on hysteresis loop shape in ferromagnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Ehrmann, Andrea; Blachowicz, Tomasz

    2014-08-01

    The dependence of the form of different mathematical depictions of fourfold magnetic anisotropies has been examined, using a simple macro-spin model. Strong differences in longitudinal and transverse hysteresis loops occur due to deviations from the usual phenomenological model, such as using absolute value functions. The proposed possible models can help understanding measurements on sophisticated magnetic nanosystems, like exchange bias layered structures employed in magnetic hard disk heads or magnetic nano-particles, and support the development of solutions with specific magnetization reversal behavior needed in novel magneto-electronic devices.

  14. Influence of fourfold anisotropy form on hysteresis loop shape in ferromagnetic nanostructures

    SciTech Connect

    Ehrmann, Andrea; Blachowicz, Tomasz

    2014-08-15

    The dependence of the form of different mathematical depictions of fourfold magnetic anisotropies has been examined, using a simple macro-spin model. Strong differences in longitudinal and transverse hysteresis loops occur due to deviations from the usual phenomenological model, such as using absolute value functions. The proposed possible models can help understanding measurements on sophisticated magnetic nanosystems, like exchange bias layered structures employed in magnetic hard disk heads or magnetic nano-particles, and support the development of solutions with specific magnetization reversal behavior needed in novel magneto-electronic devices.

  15. Visible light photoinactivation of bacteria by tungsten oxide nanostructures formed on a tungsten foil

    NASA Astrophysics Data System (ADS)

    Ghasempour, Fariba; Azimirad, Rouhollah; Amini, Abbas; Akhavan, Omid

    2015-05-01

    Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400-800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50-90 nm and crystalline phase of WO3) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K2W6O19 crystalline phase were formed on the foils. The WO3 nanorods showed a strong antibacterial property under visible light irradiation, corresponding to >92% bacterial inactivation within 24 h irradiation at room temperature, while the K2W6O19 microrods formed at 800 °C could inactivate only ∼45% of the bacteria at the same conditions.

  16. Genetically improved monolayer-forming tobacco mosaic viruses to generate nanostructured semiconducting bio/inorganic hybrids.

    PubMed

    Atanasova, Petia; Stitz, Nina; Sanctis, Shawn; Maurer, Johannes H M; Hoffmann, Rudolf C; Eiben, Sabine; Jeske, Holger; Schneider, Jörg J; Bill, Joachim

    2015-04-07

    The genetically determined design of structured functional bio/inorganic materials was investigated by applying a convective assembly approach. Wildtype tobacco mosaic virus (wt TMV) as well as several TMV mutants were organized on substrates over macroscopic-length scales. Depending on the virus type, the self-organization behavior showed pronounced differences in the surface arrangement under the same convective assembly conditions. Additionally, under varying assembly parameters, the virus particles generated structures encompassing morphologies emerging from single micrometer long fibers aligned parallel to the triple-contact line through disordered but dense films to smooth and uniform monolayers. Monolayers with diverse packing densities were used as templates to form TMV/ZnO hybrid materials. The semiconducting properties can be directly designed and tuned by the variation of the template architecture which are reflected in the transistor performance.

  17. Feature-oriented regional modeling and simulations (FORMS) for the western South Atlantic: Southeastern Brazil region

    NASA Astrophysics Data System (ADS)

    Calado, L.; Gangopadhyay, A.; da Silveira, I. C. A.

    The multi-scale synoptic circulation system in the southeastern Brazil (SEBRA) region is presented using a feature-oriented approach. Prevalent synoptic circulation structures, or "features," are identified from previous observational studies. These features include the southward-flowing Brazil Current (BC), the eddies off Cabo São Tomé (CST - 22°S) and off Cabo Frio (CF - 23°S), and the upwelling region off CF and CST. Their synoptic water-mass ( T- S) structures are characterized and parameterized to develop temperature-salinity ( T- S) feature models. Following [Gangopadhyay, A., Robinson, A.R., Haley, P.J., Leslie, W.J., Lozano, C.J., Bisagni, J., Yu, Z., 2003. Feature-oriented regional modeling and simulation (forms) in the gulf of maine and georges bank. Cont. Shelf Res. 23 (3-4), 317-353] methodology, a synoptic initialization scheme for feature-oriented regional modeling and simulation (FORMS) of the circulation in this region is then developed. First, the temperature and salinity feature-model profiles are placed on a regional circulation template and objectively analyzed with available background climatology in the deep region. These initialization fields are then used for dynamical simulations via the Princeton Ocean Model (POM). A few first applications of this methodology are presented in this paper. These include the BC meandering, the BC-eddy interaction and the meander-eddy-upwelling system (MEUS) simulations. Preliminary validation results include realistic wave-growth and eddy formation and sustained upwelling. Our future plan includes the application of these feature models with satellite, in-situ data and advanced data-assimilation schemes for nowcasting and forecasting the SEBRA region.

  18. Organo-montmorillonite Barrier Layers Formed by Combustion: Nanostructure and Permeability

    SciTech Connect

    Fox, James B; Ambuken, Preejith V.; Stretz, Holly A; Meisner, Roberta Ann; Payzant, E Andrew

    2010-01-01

    Self-assembly of nanoparticles into barrier layers has been the most cited theoretical explanation for the significant reduction in flammability often noted for nanocomposites formed from polymers and montmorillonite organoclays. Both mass and heat transport reductions have been credited for such improvements, and in most cases a coupled mechanism is expected. To provide validation for early models, new model barrier layers were produced from organoclays, and these barrier layers subjected to novel permeability analysis to obtain a flux. The effects of surfactant, temperature and pressure on barrier layer structure were examined. XRD versus TGA results suggest that chemical degradation of four different organoclays and physical collapse on heating are not correlated. Addition of pressure as low as 7kPa also altered the structure produced. Permeability of Ar through the ash was found to be sensitive to structural change/self assembly of high aspect ratio MMT nanoparticles. Actual fluxes ranged from 0.139 to 0.151 mol(m2.sec)-1, values which will provide useful limits in verifying models for the coupled contribution of mass and heat transfer to flammability parameters such as peak heat release rate.

  19. Intermolecular interactions and solvent diffusion in ordered nanostructures formed by self-assembly of block copolymers

    NASA Astrophysics Data System (ADS)

    Gu, Zhiyong

    Hydrogels formed by Poloxamer poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers find various pharmaceutical and biomedical applications. A variety of ordered structures can be exhibited by Poloxamer block copolymers in selective solvents such as water, for example, micellar cubic phase, hexagonal phase, lamellar phase, etc. We are interested in the thermodynamic and transport properties of water in such hydrogels that have an ordered (lyotropic liquid crystalline) structure. We have investigated the time evolution of water loss from Poloxamer gel films under a driving force of known water vapor pressure in the air in contact with the film. The experimental data on the drying process have been fitted to the diffusion equation for water in the film, under a boundary condition that includes the water concentration in the gel at infinite time; the water diffusion coefficient and other parameters have thus been obtained. The water chemical potential and osmotic pressure in the gel have been obtained from osmotic stress measurements. The osmotic pressure (force), together with data on the corresponding lyotropic liquid crystal spacing (distance) that we obtained from Small Angle X-Ray Scattering (SAXS) measurements, have been analyzed to provide information on the prevailing intermolecular (inter-assembly) forces in the gel. The forces in the gel reveal interactions that occur at two levels, that of the PEO coil and that of the PEO segment.

  20. The processing of polyelectrolyte-covered magnetite nanoparticles in the form of nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Marangoni, Valéria S.; Martins, Marccus Victor A.; Souza, José A.; Oliveira, Osvaldo N.; Zucolotto, Valtencir; Crespilho, Frank N.

    2012-03-01

    Magnetic nanoparticles are promising for a variety of applications, such as biomedical devices, spin electronics, magnetic data storage media, to name a few. However, these goals may only be reached if stable and organized structures are fabricated. In this article, we report on a single-step synthetic route with the coprecipitation method, in which iron oxide magnetic nanoparticles (Fe3O4 NPs) were stabilized in aqueous media using the poly(diallyldimethylammonium chloride) (PDAC) polyelectrolyte. The Fe3O4 NPs had a diameter of ca. 5 nm, according to transmission electron microscopy (TEM) images, being arranged in an inverse spinel structure typical of magnetite. An investigation with infrared spectroscopy indicated that the mechanisms of stabilization in the polymer matrix were based on the interaction between quaternary amide groups from PDAC and the nanoparticle surface. The Fe3O4-PDAC NPs exhibited considerable magnetic susceptibility, with a monotonic increase in the magnetization with decreasing temperature. These Fe3O4-PDAC NPs were immobilized in layer-by-layer (LbL) films, being alternated with layers of poly(vinylsulfonic acid) (PVS). The LbL films were much rougher than typical films made with polyelectrolytes, and Fe3O4-PDAC NPs have been responsible for the high electrocatalytic activity toward H2O2 reduction, with an overpotential shift of 0.69 V. Overall, the stability, magnetic properties and film-forming ability indicate that the Fe3O4-PDAC NPs may be used for nanoelectronics and bioelectrochemical devices requiring reversible and magnetic redox materials.

  1. Optical anisotropy of quasi-1D rare-earth silicide nanostructures on Si(001)

    NASA Astrophysics Data System (ADS)

    Chandola, S.; Speiser, E.; Esser, N.; Appelfeller, S.; Franz, M.; Dähne, M.

    2017-03-01

    Rare earth metals are known to interact strongly with Si(001) surfaces to form different types of silicide nanostructures. Using STM to structurally characterize Dy and Tb silicide nanostructures on vicinal Si(001), it will be shown that reflectance anisotropy spectroscopy (RAS) can be used as an optical fingerprint technique to clearly distinguish between the formation of a semiconducting two-dimensional wetting layer and the metallic one-dimensional nanowires. Moreover, the distinctive spectral features can be related to structural units of the nanostructures. RAS spectra of Tb and Dy nanostructures are found to show similar features.

  2. Form drag in rivers due to small-scale natural topographic features: 2. Irregular sequences

    NASA Astrophysics Data System (ADS)

    Kean, Jason W.; Smith, J. Dungan

    2006-12-01

    The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two-dimensional elements with Gaussian-shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.

  3. Form drag in rivers due to small-scale natural topographic features: 2. Irregular sequences

    USGS Publications Warehouse

    Kean, J.W.; Smith, J.D.

    2006-01-01

    The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two-dimensional elements with Gaussian-shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.

  4. Plastic deformation drives wrinkling, saddling and wedging of annular bilayer nanostructures

    PubMed Central

    Cho, Jeong-Hyun; Datta, Dibakar; Park, Si-Young; Shenoy, Vivek B.; Gracias, David H.

    2010-01-01

    We describe the spontaneous wrinkling, saddling, and wedging of metallic, annular bilayer nanostructures driven by grain coalescence in one of the layers. Experiments revealed these different outcomes based on the dimensions of the annuli and we find that the essential features are captured using finite element simulations of the plastic deformation in the metal bilayers. Our results show that the dimensions and nanomechanics associated with the plastic deformation of planar nanostructures can be important in forming complex three dimensional nanostructures. PMID:21090597

  5. Distinctive features of the microbiota associated with different forms of apical periodontitis

    PubMed Central

    Siqueira, José F.; Rôças, Isabela N.

    2009-01-01

    Microorganisms infecting the dental root canal system play an unequivocal role as causative agents of apical periodontitis. Although fungi, archaea, and viruses have been found in association with some forms of apical periodontitis, bacteria are the main microbial etiologic agents of this disease. Bacteria colonizing the root canal are usually organized in communities similar to biofilm structures. Culture and molecular biology technologies have demonstrated that the endodontic bacterial communities vary in species richness and abundance depending on the different types of infection and different forms of apical periodontitis. This review paper highlights the distinctive features of the endodontic microbiota associated with diverse clinical conditions. PMID:21523208

  6. Distinctive features of the microbiota associated with different forms of apical periodontitis.

    PubMed

    Siqueira, José F; Rôças, Isabela N

    2009-08-10

    Microorganisms infecting the dental root canal system play an unequivocal role as causative agents of apical periodontitis. Although fungi, archaea, and viruses have been found in association with some forms of apical periodontitis, bacteria are the main microbial etiologic agents of this disease. Bacteria colonizing the root canal are usually organized in communities similar to biofilm structures. Culture and molecular biology technologies have demonstrated that the endodontic bacterial communities vary in species richness and abundance depending on the different types of infection and different forms of apical periodontitis. This review paper highlights the distinctive features of the endodontic microbiota associated with diverse clinical conditions.

  7. Features of the magnetic state of the layered Fe-V nanostructure of the superconductor-ferromagnet type

    SciTech Connect

    Aksenov, V. L.; Nikitenko, Yu. V.; Petrenko, A. V.; Uzdin, V. M.; Khaidukov, Yu. N. Zabel, H.

    2007-05-15

    The magnetic state of the V(39 nm)/20 [V(3 nm)/Fe(3 nm)] nanostructure has been investigated by polarized neutron reflectometry in the temperature range from 1.6 to 30 K in magnetic fields from 0.2 to 15 kOe. The data obtained indicate that the superconductivity of vanadium layers may affect magnetic ordering both over the depth of the structure and in its plane.

  8. Utilization of Network-Forming Block Copolymers and Ionomers in the Development of Novel Nanostructures and Responsive Media

    NASA Astrophysics Data System (ADS)

    Mineart, Kenneth

    Network forming block copolymers, i.e. thermoplastic elastomers (TPEs), are one of the highest commodity forms of block copolymers due to their competitive elasticity and extendability as well as their ability to be melt and solution processed. TPEs owe many of their advantages to a combination of hard and soft blocks. The soft blocks, which must be covalently bound at both ends to hard blocks, connect adjacent hard domains resulting in physically cross-linked systems. Herein, simulations and theory are used to provide a molecular-level depiction of the evolution from diblock copolymers, which do not contain the ability to form physical cross-links, to network forming triblock copolymers. In addition, systems with high interblock incompatibility that are within the diblock-to-triblock transition (i.e. having high molecular asymmetry) are identified to form three component (ABC triblock copolymer) phases from copolymer containing only two chemically distinct blocks. Following this work, which emphasizes the fundamental principle of TPEs, the dissertation shifts focus to physically- and chemically-modified triblock and pentablock copolymer TPEs. Recent progress has sought to broaden TPEs to include properties that are above and beyond their inherent mechanical benefits, including responsiveness to external stimuli. The first examples presented here consist of TPEs prepared in combination with amorphous hydrocarbon additives to yield TPE gels (TPEGs). The resulting TPEGs, which maintain the beneficial processing properties of TPEs, are subsequently molded into 1- and 2-D arrays of microchannels that are filled with liquid metal. The final devices exhibit strain-sensitive electrical conductivity to at least 600% strain, have tunable compliance (ease of stretching), and are fully recyclable. The substitution of the amorphous hydrocarbon component for crystalline analogues with melting points <100 °C yield TPE composites (TPECs). The TPECs gain the added capability of

  9. FUNCTION FOLLOWS FORM: ACTIVATION OF SHAPE & FUNCTION FEATURES DURING OBJECT IDENTIFICATION

    PubMed Central

    Yee, Eiling; Huffstetler, Stacy; Thompson-Schill, Sharon L.

    2011-01-01

    Most theories of semantic memory characterize knowledge of a given object as comprising a set of semantic features. But how does conceptual activation of these features proceed during object identification? We present the results of a pair of experiments that demonstrate that object recognition is a dynamically unfolding process in which function follows form. We used eye movements to explore whether activating one object’s concept leads to the activation of others that share perceptual (shape) or abstract (function) features. Participants viewed four-picture displays and clicked on the picture corresponding to a heard word. In critical trials, the conceptual representation of one of the objects in the display was similar in shape or function (i.e., its purpose) to the heard word. Importantly, this similarity was not apparent in the visual depictions (e.g., for the target “frisbee,” the shape-related object was a triangular slice of pizza – a shape that a frisbee cannot take); preferential fixations on the related object were therefore attributable to overlap of the conceptual representations on the relevant features. We observed relatedness effects for both shape and function, but shape effects occurred earlier than function effects. We discuss the implications of these findings for current accounts of the representation of semantic memory. PMID:21417543

  10. Electroretinogram and visual evoked response in a form of `neuronal lipidosis' with diagnostic EEG features

    PubMed Central

    Harden, Ann; Pampiglione, G.; Picton-Robinson, N.

    1973-01-01

    Combined recordings of the electroretinogram (ERG) and the cortical visual evoked response (VER) have been made together with the electroencephalogram (EEG) in 16 children suffering from a `late infantile' form of `neuronal lipidosis'. The ERG was not usually recordable, in keeping with a gross loss of function of the retinal receptor elements. However, in all the 16 children, at whatever stage of the disease, a grossly enlarged VER was seen (some 12 to 20 times higher in amplitude than in a control group) and visible as a discharge on the primary EEG tracing. The first components of the VER were, however, of fairly similar wave form and latency to those seen in the control children. This unusual combination of ERG and VER findings together with the EEG features have not been found in other groups of diseases. PMID:4691692

  11. One-step growth of Si{sub 3}N{sub 4} stem-branch featured nanostructures: Morphology control by VS and VLS mode

    SciTech Connect

    Wang Qiushi; Gao Wei; Shan Lianchen; Zhang Jian; Jin Yunxia; Cong Ridong; Cui Qiliang

    2011-09-15

    We report here one-step synthesis of Si{sub 3}N{sub 4} nanodendrites by selectively applying a vapor-solid (VS) and vapor-liquid-solid (VLS) strategy via direct current arc discharge method. The resultant nanodendrites were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray powder diffraction. The spine-shaped nanodendrites were generated by a noncatalytic growth following a VS mode. The uniform secondary nanowire branches were epitaxial grown from two side surfaces of the nanowire stems. The pine-shaped nanodendrites were obtained through a catalytic growth in a VLS process. These branch nanowires were unsystematically grown from the nanocone-like stems. The photoluminescence spectra of the nanodendrites show a strong white light emission around 400-750 nm, suggesting their potential applications in light and electron emission devices. - Graphical abstract: Spine-shaped and pine-shaped Si{sub 3}N{sub 4} hierarchical nanostructures were synthesized by VS and VLS mode with plasma-assisted dc arc discharge method. Highlights: > Si{sub 3}N{sub 4} stem-branch featured nanostructures have been prepared. > Spine-shaped nanodendrites were generated by a noncatalytic growth following a VS mode. > Pine-shaped nanodendrites were obtained through a catalytic growth in a VLS process.

  12. Design, assembly, and activity of antisense DNA nanostructures.

    PubMed

    Keum, Jung-Won; Ahn, Jin-Ho; Bermudez, Harry

    2011-12-16

    Discrete DNA nanostructures allow simultaneous features not possible with traditional DNA forms: encapsulation of cargo, display of multiple ligands, and resistance to enzymatic digestion. These properties suggested using DNA nanostructures as a delivery platform. Here, DNA pyramids displaying antisense motifs are shown to be able to specifically degrade mRNA and inhibit protein expression in vitro, and they show improved cell uptake and gene silencing when compared to linear DNA. Furthermore, the activity of these pyramids can be regulated by the introduction of an appropriate complementary strand. These results highlight the versatility of DNA nanostructures as functional devices.

  13. Colonization by Staphylococcus aureus of Nano-Structured Fluorinated Surfaces, Formed by Different Methods of Ion-Plasma Technology.

    PubMed

    Elinson, V M; Didenko, L V; Shevlyagina, N V; Avtandilov, G A; Gaidarova, A Kh; Lyamin, A N

    2016-11-01

    Colonization of fluorinated surfaces produced by ion-plasma technology by Staphylococcus aureus was studied by scanning electron microscopy and surface energy analysis. It was shown that the intensity of colonization was determined by the surface relief and fluorine content. Formation of nanostructured surfaces accompanied by a sharp decrease in the surface energy prevented adhesion of Staphylococcus aureus cells to the fluorine-containing surface.

  14. Photocurrent detection of chemically tuned hierarchical ZnO nanostructures grown on seed layers formed by atomic layer deposition

    PubMed Central

    2012-01-01

    We demonstrate the morphological control method of ZnO nanostructures by atomic layer deposition (ALD) on an Al2O3/ZnO seed layer surface and the application of a hierarchical ZnO nanostructure for a photodetector. Two layers of ZnO and Al2O3 prepared using ALD with different pH values in solution coexisted on the alloy film surface, leading to deactivation of the surface hydroxyl groups. This surface complex decreased the ZnO nucleation on the seed layer surface, and thereby effectively screened the inherent surface polarity of ZnO. As a result, a 2-D zinc hydroxyl compound nanosheet was produced. With increasing ALD cycles of ZnO in the seed layer, the nanostructure morphology changes from 2-D nanosheet to 1-D nanorod due to the recovery of the natural crystallinity and polarity of ZnO. The thin ALD ZnO seed layer conformally covers the complex nanosheet structure to produce a nanorod, then a 3-D, hierarchical ZnO nanostructure was synthesized using a combined hydrothermal and ALD method. During the deposition of the ALD ZnO seed layer, the zinc hydroxyl compound nanosheets underwent a self-annealing process at 150 °C, resulting in structural transformation to pure ZnO 3-D nanosheets without collapse of the intrinsic morphology. The investigation on band electronic properties of ZnO 2-D nanosheet and 3-D hierarchical structure revealed noticeable variations depending on the richness of Zn-OH in each morphology. The improved visible and ultraviolet photocurrent characteristics of a photodetector with the active region using 3-D hierarchical structure against those of 2-D nanosheet structure were achieved. PMID:22672780

  15. Structural and optical properties of ZnMgO nanostructures formed by Mg in-diffused ZnO nanowires

    SciTech Connect

    Pan, C.-J.; Hsu, H.-C.; Cheng, H.-M.; Wu, C.-Y.; Hsieh, W.-F.

    2007-04-15

    ZnMgO nanostructures with wurtzite phase were prepared by thermal diffusion of Mg into the ZnO nanowires. As ZnO light-emitting devices have been operated by using ZnMgO layers as energy barrier layers to confine the carriers, it is essential to realize the characterization of ZnMgO particularly. In this work, the Mg content in Zn{sub 1} {sub -x} Mg {sub x} O alloy determined by X-ray diffraction (XRD) and photoluminescence (PL) shows a good coincidence. The variation of lattice constant and the blueshift of near-band-edge emission indicate that Zn{sup 2+} ions are successfully substituted by Mg{sup 2+} ions in the ZnO lattice. In Raman-scattering studies, the change of E {sub 2}(high) phonon line shape in ZnO:Mg nanostructures reveals the microscopic substitutional disorder. In addition to the host phonons of ZnO, two additional bands around 383 and 510 cm{sup -1} are presumably attributed to the Mg-related vibrational modes. - Graphical abstract: We reported the synthesis of the ZnMgO nanostructures prepared by a simple vapor transport method. Magnesium-related anomalous modes are observed by Raman spectra for the first time in ZnMgO system.

  16. Enhanced apatite-forming ability and cytocompatibility of porous and nanostructured TiO2/CaSiO3 coating on titanium.

    PubMed

    Hu, Hongjie; Qiao, Yuqin; Meng, Fanhao; Liu, Xuanyong; Ding, Chuanxian

    2013-01-01

    To improve the bioactivity and cytocompatibility of biomedical titanium dioxide coating, many efforts have been made to modify its surface composition and topography. Meanwhile, CaSiO(3) was commonly investigated as coating material on titanium implants for fast fixation and firm implant-bone attachment due to its demonstrated bioactivity and osteointegration. In this work, gradient TiO(2)/CaSiO(3) coating on titanium was prepared by a two-step procedure, in which porous and nanostructured TiO(2) coating on titanium was prepared by plasma electrolytic oxidation in advance, and then needle and flake-like CaSiO(3) nanocrystals were deposited on the TiO(2) coating surface by electron beam evaporation. In view of the potential clinical applications, apatite-forming ability of the TiO(2)/CaSiO(3) coating was evaluated by simulated body fluid (SBF) immersion tests, and MG63 cells were cultured on the surface of the coating to investigate its cytocompatibility. The results show that deposition of CaSiO(3) significantly enhanced the apatite-forming ability of nanostructured TiO(2) coating in SBF. Meanwhile, the MG63 cells on TiO(2)/CaSiO(3) coating show higher proliferation rate and vitality than that on TiO(2) coating. In conclusion, the porous and nanostructured TiO(2)/CaSiO(3) coating on titanium substrate with good apatite-forming ability and cytocompatibility is a potential candidate for bone tissue engineering and implant coating.

  17. Fractal features of soil particle size distribution in newly formed wetlands in the Yellow River Delta

    PubMed Central

    Yu, Junbao; Lv, Xiaofei; Bin, Ma; Wu, Huifeng; Du, Siyao; Zhou, Mo; Yang, Yanming; Han, Guangxuan

    2015-01-01

    The characteristic of particle size distribution (PSD) in the newly formed wetlands in coast has seldom been studied. We applied fractal-scaling theory in assessing soil particle size distribution (PSD) features of newly formed wetlands in the Yellow River Delta (YRD), China. The singular fractal dimensions (D) values ranged from 1.82 to 1.90, the capacity dimension (D0) values ranged from 0.84 to 0.93, and the entropy dimension (D1) values ranged from 0.66 to 0.84. Constrained corresponding analysis revealed that 43.5% of the variance in soil PSD can be explained by environmental factors, including 14.7% by seasonal variation, 8.6% by soil depth, and 8.0% by vegetation type. The fractal dimensions D and D1 were sensitive with fine particles with size ranging less than 126 μm, and D0 was sensitive with coarse particles with size ranging between 126 μm to 2000 μm. Fractal analysis makes full use of soil PSD information, and offers a useful approach to quantify and assess the soil physical attributes in the newly formed wetland. PMID:26014107

  18. Channels and valleys on Mars: Cold climate features formed as a result of a thickening cryosphere

    USGS Publications Warehouse

    Carr, M.H.

    1996-01-01

    Large flood channels, valley networks, and a variety of features attributed to the action of ground ice indicate that Mars emerged from heavy bombardment around 3.8Gyr ago, with an inventory of water at the surface equivalent to at least a few hundred meters spread over the whole planet, as compared with 3 km for the Earth. The surface water resided primarily in a porous, kilometers thick, megaregolith created by the high impact rates. At the end of heavy bombardment a rapid decline in erosion rates by a factor of 1000 suggests a major change in the global climate. It is proposed that at this time the climate became similar to today's and that this climate has been maintained throughout the rest of Mars' history. The various drainage features represent an adjustment of the distribution of water to the surface relief inherited from the period of heavy bombardment and to a thickening of the cryosphere as the heat flow declined. The valley networks formed mostly at the end of heavy bombardment when erosion rates were high and climatic conditions permitted an active water cycle. They continued to form after heavy bombardment when the cryosphere started to form by a combination of episodic flooding and mass-wasting aided by the presence of liquid water at shallow depths. As the cryosphere thickened with declining heat flow, water could no longer easily access the surface and the rate of valley formation declined. Hydrostatic pressures built below the cryosphere. Eruptions of groundwater became more catastrophic and massive floods resulted, mainly in upper Hesperian time. Flood sources were preferentially located in low-lying, low-latitude areas where the cryosphere was thin, or near volcanoes where a thinner than typical cryosphere is also expected. Floods caused a drawdown in the global water table so that few formed in the second half of Mars' history. The floodwaters pooled in low-lying areas, mostly in the northern plains. Some of the water may still be present as

  19. Characterization and optimization of illumination vector for contouring surface form and feature using DSPI

    NASA Astrophysics Data System (ADS)

    Song, Chaolong; Prasad A. S., Guru; Chan, Kelvin H. K.; Murukeshan, Vadakke Matham

    2016-06-01

    Surface defect or damage is one of the critical factors leading to the failure of engineering materials and structures. The methodologies for the measurement of surface shape and feature or defect have been extensively explored and developed over the past few decades, including both contact and non-contact methods. Speckle pattern interferometry, as a non-contact optical method, has been demonstrated to effectively contour the surface shape through adjusting the illumination vector. However, few studies have been made to investigate the effect of the initial position of the illumination source as well as the source translation direction. In this paper, we report to carry out a study of measuring the surface form and feature using digital speckle pattern interferometry system via a slight translation of illumination source. Through theoretically analyzing the sensitivity factor along with the experimental validation, it is shown that the contouring fringe is more sensitive to the surface height with an off-axis illumination than the paraxial illumination. It is also found that translating the source along axial and lateral direction can be both used for the surface shape re-construction.

  20. [Histological features of tumor-bearing tissues formed by human fibroblasts after reprograming by Piwil2].

    PubMed

    Zeng, Guangping; Wu, Xin; He, Dawei; Fu, Yiyao; Liu, Xing; Zhang, Deying; Lin, Tao; Wei, Guanghui

    2015-08-01

    To observe the histological features of tumor-bearing tissues formed by human fibroblasts after reprograming by spermatogonial stem cell self-renewal key regulating gene Piwil2 (Piwil2-iCSC). Piwil2-iCSC tumor spheroids-like colonies were selected for tumor formation assay in four nude mice. Pathological features of Piwil2-iCSC tumors were observed by histology. Stem cell markers and common triploblastic markers were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) assay and immunohistochemistry. Germ cell tumor markers were detected by immunohistochemical examination. Two weeks after inoculation, subcutaneous tumors were formed in all the four nude mice with a tumor formation rate of 100%. In the Piwil2-iCSC tumor tissues, Piwil2-GFP(+) cells showed high-density nuclear expression and were widely observed in DAPI-stained sections. Numerous mitotic figure of the neoplastic cells were seen (>10 cells/field of vision under high magnification) in HE-stained sections. Enlarged abnormal cell nuclei were observed. RT-PCR assay showed that Piwil2-iCSC tumors still expressed Piwil2 and some self-renewal and pluripotent markers of stem cells and some markers of triploblastic differentiation. Immunohistochemical staining showed that the tumors expressed stem cell markers, triploblastic markers and germ cell tumor markers AFP and HCG. Piwil2-iCSC tumors are probably undifferentiated embryonic small cell carcinoma, most likely to be immature teratoma, mixed with yolk sac tumor and choriocarcinoma components. It can be used as a useful model for the research of origin or genesis mechanism of cancer stem cells and the treatment of relevant tumors.

  1. Robust broadband beam-forming based on the feature of underwater target radiated noise

    NASA Astrophysics Data System (ADS)

    Chen, Xin-hua; Liu, Chao; Yu, Hua-bing; Zheng, En-ming; Sun, Chang-yu

    2016-12-01

    To the problem of the unknown underwater target detection, according to the feature that the underwater target radiated noise contains the stable line spectrum, a weighted method based on the main-to-side lobe ratio (MSLR) is proposed for broadband beam-forming. This weighted method can be implemented by using the following steps. Firstly, optimize the spatial spectrum of each frequency unit by the second-order cone programming (SOCP), and obtain the optimized spatial spectrum with lower side lobe. Secondly, construct weighting factors based on the MSLR of the optimized spatial spectrums to from weight factors. Lastly, cumulate the spatial spectrum of each frequency unit via the weight statistical method of this paper. This method can restrain the disturbance of background noise, enhance the output signal-to-noise ratio (SNR), and overcome the difficulty of traditional four-dimensional display. The theoretical analysis and simulation results both verify that this method can well enhance the spatial spectrum of line spectrum units, restrain the spatial spectrum of background noise units, and improve the performance of the broadband beam-forming.

  2. Fresh shallow valleys in the Martian midlatitudes as features formed by meltwater flow beneath ice

    NASA Astrophysics Data System (ADS)

    Hobley, Daniel E. J.; Howard, Alan D.; Moore, Jeffrey M.

    2014-01-01

    Significant numbers of valleys have been identified in the Martian midlatitudes (30-60°N/S), spatially associated with extant or recent ice accumulations. Many of these valleys date to the Amazonian, but their formation during these cold, dry epochs is problematic. In this study, we look in detail at the form, distribution, and quantitative geomorphology of two suites of these valleys and their associated landforms in order to better constrain the processes of their formation. Since the valleys themselves are so young and thus well preserved, uniquely, we can constrain valley widths and courses and link these to the topography from the Mars Orbiter Laser Altimeter and High-Resolution Stereo Camera data. We show that the valleys are both qualitatively and quantitatively very similar, despite their being >5000 km apart in different hemispheres and around 7 km apart in elevation. Buffered crater counting indicates that the ages of these networks are statistically identical, probably forming during the Late Amazonian, ~100 Ma. In both localities, at least tens of valleys cross local drainage divides, apparently flowing uphill. We interpret these uphill reaches to be characteristic of flow occurring beneath a now absent, relatively thin (order 101-102 m), regionally extensive ice cover. Ridges and mounds occasionally found at the foot of these valley systems are analogous to eskers and aufeis-like refreezing features. On the basis of their interaction with these aufeis-like mounds, we suggest that this suite of landforms may have formed in a single, short episode (perhaps order of days), probably forced by global climate change.

  3. Nanostructured protic ionic liquids retain nanoscale features in aqueous solution while precursor Brønsted acids and bases exhibit different behavior.

    PubMed

    Greaves, Tamar L; Kennedy, Danielle F; Weerawardena, Asoka; Tse, Nicholas M K; Kirby, Nigel; Drummond, Calum J

    2011-03-10

    Small- and wide-angle X-ray scattering (SWAXS) has been used to investigate the effect that water has on the nanoscale structure of protic ionic liquids (PILs) along with their precursor Brønsted acids and bases. The series of PILs consisted of primary, secondary, and tertiary alkylammonium cations in conjunction with formate, nitrate, or glycolate anions. Significant differences were observed for these systems. The nanoscale aggregates present in neat protic ionic liquids were shown to be stable in size on dilution to high concentrations of water, indicating that the water is localized in the ionic region and has little effect on the nonpolar domains. The Brønsted acid-water solutions did not display nanostructure at any water concentration. Primary amine Brønsted bases formed aggregates in water, which generally displayed characteristics of poorly structured microemulsions or a form of bicontinuous phase. Exceptions were butyl- and pentylamine with high water concentrations, for which the SWAXS patterns fitted well to the Teubner-Strey model for microemulsions. Brønsted base amines containing multiple alkyl chains or hydroxyl groups did not display nanostructure at any water concentration. IR spectroscopy was used to investigate the nature of water in the various solutions. For low PIL concentrations, the water was predominately present as bulk water for PIL molar fractions less than 0.4-0.5. At high PIL concentrations, in addition to the bulk water, there was a significant proportion of perturbed water, which is water influenced in some way by the cations and anions. The molecular state of the water in the studied amines was predominately present as bulk water, with smaller contributions from perturbed water than was seen in the PILs. © 2011 American Chemical Society

  4. Influence of the sputtering pressure on the morphological features and electrical resistivity anisotropy of nanostructured titanium films

    NASA Astrophysics Data System (ADS)

    Pedrosa, Paulo; Ferreira, Armando; Cote, Jean-Marc; Martin, Nicolas; Yazdi, Mohammad Arab Pour; Billard, Alain; Lanceros-Mendez, Senentxu; Vaz, Filipe

    2017-10-01

    Titanium films were DC sputtered with a particle flux incidence angle of 80°, using the Glancing Angle Deposition (GLAD) technique with increasing sputtering pressures from 0.2 to 1.5 Pa. This range of pressures is typically implemented for the deposition of thin films by the magnetron sputtering process. The main objective of this work was to study the anisotropic electrical resistivity behaviour of the different thin film nanostructures that were obtained. It is shown that low sputtering pressures (0.2-0.5 Pa) promote higher column angles β with respect to the substrate normal (15° ≤ β ≤ 40°), as well as better defined porous structures. On the other hand, intermediate and high pressures (0.6-0.8 Pa) originate secondary growth effects on the columnar structures perpendicular to the substrate normal (β = 0°). No defined columns can be seen when the films are sputtered using the highest pressure (1.5 Pa). The electrical resistivity is significantly affected by the differences in the columnar microstructure. Porous films exhibit higher room temperature (RT) resistivity values (0.95-1.5 × 10-5 Ω m), when compared to the more compact ones (0.6-0.9 × 10-5 Ω m). When a temperature cycle of RT(25)-300-RT(25) °C was applied, a more significant oxidation is evidenced in the more porous structures, as well as a higher resistivity anisotropy (maximum of 1.6) than in the more compact ones (minimum of 1.25).

  5. New Features of Disease after Diagnosis in Six Forms of Systemic Vasculitis

    PubMed Central

    Grayson, Peter C.; Cuthbertson, David; Carette, Simon; Hoffman, Gary S.; Khalidi, Nader A.; Koening, Curry L.; Langford, Carol A.; Maksimowicz-McKinnon, Kathleen; Monach, Paul A.; Seo, Philip; Specks, Ulrich; Ytterberg, Steven R.; Merkel, Peter A.

    2015-01-01

    Objective To quantify the occurrence of features of vasculitis that initially present after diagnosis in 6 types of primary vasculitis. Methods Standardized collection of data on 95 disease manifestations in 6 vasculitides, including granulomatosis with polyangiitis (Wegener's, GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (Churg-Strauss, EGPA), polyarteritis nodosa (PAN), giant cell arteritis (GCA), and Takayasu's arteritis (TAK), was performed within a set of multicenter longitudinal, observational cohorts. For each form of vasculitis, the frequency of disease-specific manifestations at diagnosis was compared to the cumulative frequency of each manifestation. The percentage of patients who initially developed “severe” manifestations after diagnosis, defined as organ- or life-threatening in the small and medium vessel vasculitides (GPA, MPA, EGPA, PAN) and as ischemic/vascular in the large vessel vasculitides (GCA, TAK), was reported. Results Out of 838 patients with vasculitis, 490 (59%) experienced ≥ 1 new disease manifestation after diagnosis. On average, patients with vasculitis experienced 1.3 new manifestations after diagnosis (GPA - 1.9, MPA - 1.2, EGPA - 1.5, PAN - 1.2, GCA - 0.7, TAK - 1.0). New severe manifestations occurred after diagnosis in 224 (27%) out of 838 patients (GPA - 26%, MPA - 19%, EGPA - 21%, PAN - 23%, GCA - 24%, and TAK - 44%). Timing of onset of new manifestations was not significantly associated with disease duration. Conclusion A majority of patients with vasculitis develop new disease features after diagnosis, including a substantial number of new, severe manifestations. Ongoing assessment of patients with established vasculitis should remain broad in scope. PMID:23908447

  6. Nanostructured photovoltaics

    NASA Astrophysics Data System (ADS)

    Fu, Lan; Tan, H. Hoe; Jagadish, Chennupati

    2013-01-01

    Energy and the environment are two of the most important global issues that we currently face. The development of clean and sustainable energy resources is essential to reduce greenhouse gas emission and meet our ever-increasing demand for energy. Over the last decade photovoltaics, as one of the leading technologies to meet these challenges, has seen a continuous increase in research, development and investment. Meanwhile, nanotechnology, which is considered to be the technology of the future, is gradually revolutionizing our everyday life through adaptation and incorporation into many traditional technologies, particularly energy-related technologies, such as photovoltaics. While the record for the highest efficiency is firmly held by multijunction III-V solar cells, there has never been a shortage of new research effort put into improving the efficiencies of all types of solar cells and making them more cost effective. In particular, there have been extensive and exciting developments in employing nanostructures; features with different low dimensionalities, such as quantum wells, nanowires, nanotubes, nanoparticles and quantum dots, have been incorporated into existing photovoltaic technologies to enhance their performance and/or reduce their cost. Investigations into light trapping using plasmonic nanostructures to effectively increase light absorption in various solar cells are also being rigorously pursued. In addition, nanotechnology provides researchers with great opportunities to explore the new ideas and physics offered by nanostructures to implement advanced solar cell concepts such as hot carrier, multi-exciton and intermediate band solar cells. This special issue of Journal of Physics D: Applied Physics contains selected papers on nanostructured photovoltaics written by researchers in their respective fields of expertise. These papers capture the current excitement, as well as addressing some open questions in the field, covering topics including the

  7. Fast classification of meat spoilage markers using nanostructured ZnO thin films and unsupervised feature learning.

    PubMed

    Längkvist, Martin; Coradeschi, Silvia; Loutfi, Amy; Rayappan, John Bosco Balaguru

    2013-01-25

    This paper investigates a rapid and accurate detection system for spoilage in meat. We use unsupervised feature learning techniques (stacked restricted Boltzmann machines and auto-encoders) that consider only the transient response from undoped zinc oxide, manganese-doped zinc oxide, and fluorine-doped zinc oxide in order to classify three categories: the type of thin film that is used, the type of gas, and the approximate ppm-level of the gas. These models mainly offer the advantage that features are learned from data instead of being hand-designed. We compare our results to a feature-based approach using samples with various ppm level of ethanol and trimethylamine (TMA) that are good markers for meat spoilage. The result is that deep networks give a better and faster classification than the feature-based approach, and we thus conclude that the fine-tuning of our deep models are more efficient for this kind of multi-label classification task.

  8. Specific features of a rare form of disseminated necrobiosis lipoidica granuloma annulare type: a case report.

    PubMed

    Ianoşi, Simona Laura; Tutunaru, Cristina; Georgescu, Claudia Valentina; Ianoşi, Nicolae Gabriel; Georgescu, Diana Monica; Dănoiu, Suzana; Niculescu, Elena Carmen; Neagoe, Carmen Daniela

    2014-01-01

    Necrobiosis lipoidica (NL) is a rare dermatosis that has been shown to precede the onset of diabetes mellitus in 15% of patients. It is more common in women; the average age of the onset is 30 years. Skin lesions of classic NL begin as a small papule, typically on the bilateral pretibial area. Progressively, these papules become indurated plaques with an atrophic, yellow center and multiple telangiectatic vessels, and brown-violaceous borders. We present the case of a 57-year-old male with type II diabetes mellitus from 2004, class II obesity, hepatosteatosis and metabolic disturbances who presents a disseminated eruption from 2010, formed by indurated plaques with flattened centers and a tendency of atrophy and raised, sharply demarcated, red-violaceous borders, having a variable diameter between 1.5 and 5 cm. The laboratory findings revealed elevated glucose levels between 250 and 300 mg%, high levels of transaminases and lipids. Diagnosis of disseminated necrobiosis lipoidica granuloma annulare-type was histopathologically confirmed. For the treatment, we have used topical corticosteroids and Tacrolimus 0.1% and systemic vasodilators. We consider this rare case interesting because has some peculiarities, as: disseminated lesions extend over the characteristic areas for necrobiosis lipoidica, the characteristic features of lesions similar to granuloma annulare, gender (male) and the onset of the disease over fifth decade.

  9. Characterization of Ag-porous silicon nanostructured layer formed by an electrochemical etching of p-type silicon surface for bio-application

    NASA Astrophysics Data System (ADS)

    Naddaf, M.; Al-Mariri, A.; Haj-Mhmoud, N.

    2017-06-01

    Nanostructured layers composed of silver-porous silicon (Ag-PS) have been formed by an electrochemical etching of p-type (1 1 1) silicon substrate in a AgNO3:HF:C2H5OH solution at different etching times (10 min-30 min). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) results reveal that the produced layers consist of Ag dendrites and a silicon-rich porous structure. The nanostructuring nature of the layer has been confirmed by spatial micro-Raman scattering and x-ray diffraction techniques. The Ag dendrites exhibit a surface-enhanced Raman scattering (SERS) spectrum, while the porous structure shows a typical PS Raman spectrum. Upon increasing the etching time, the average size of silicon nanocrystallite in the PS network decreases, while the average size of Ag nanocrystals is slightly affected. In addition, the immobilization of prokaryote Salmonella typhimurium DNA via physical adsorption onto the Ag-PS layer has been performed to demonstrate its efficiency as a platform for detection of biological molecules using SERS.

  10. Self-seeding in one dimension: a route to uniform fiber-like nanostructures from block copolymers with a crystallizable core-forming block.

    PubMed

    Qian, Jieshu; Lu, Yijie; Chia, Anselina; Zhang, Meng; Rupar, Paul A; Gunari, Nikhil; Walker, Gilbert C; Cambridge, Graeme; He, Feng; Guerin, Gerald; Manners, Ian; Winnik, Mitchell A

    2013-05-28

    One-dimensional micelles formed by the self-assembly of crystalline-coil poly(ferrocenyldimethylsilane) (PFS) block copolymers exhibit self-seeding behavior when solutions of short micelle fragments are heated above a certain temperature and then cooled back to room temperature. In this process, a fraction of the fragments (the least crystalline fragments) dissolves at elevated temperature, but the dissolved polymer crystallizes onto the ends of the remaining seed fragments upon cooling. This process yields longer nanostructures (up to 1 μm) with uniform width (ca. 15 nm) and a narrow length distribution. In this paper, we describe a systematic investigation of factors that affect the self-seeding behavior of PFS block copolymer micelle fragments. For PI(1000)-PFS(50) (the subscripts refer to the number average degree of polymerization) in decane, these factors include the presence of a good solvent (THF) for PFS and the effect of annealing the fragments prior to the self-seeding experiments. THF promoted the dissolution of the micelle fragments, while preannealing improved their stability. We also extended our experiments to other PFS block copolymers with different corona-forming blocks. These included PI(637)-PFS(53) in decane, PFS(60)-PDMS(660) in decane (PDMS = polydimethylsiloxane), and PFS(30)-P2VP(300) in 2-propanol (P2VP = poly(2-vinylpyridine)). The most remarkable result of these experiments is our finding that the corona-forming chain plays an important role in affecting how the PFS chains crystallize in the core of the micelles and, subsequently, the range of temperatures over which the micelle fragments dissolve. Our results also show that self-seeding is a versatile approach to generate uniform PFS fiber-like nanostructures, and in principle, the method should be extendable to a wide variety of crystalline-coil block copolymers.

  11. Comparative skeletal muscle histopathologic and ultrastructural features in two forms of polysaccharide storage myopathy in horses.

    PubMed

    McCue, M E; Armién, A G; Lucio, M; Mickelson, J R; Valberg, S J

    2009-11-01

    Polysaccharide storage myopathy (PSSM) has been found in more than 35 different horse breeds through identification of abnormal storage of polysaccharide in muscle biopsies. A dominant mutation in the glycogen synthase 1 gene (GYS1) accounts for a substantial proportion of PSSM cases in at least 17 breeds, including Quarter Horses, but some horses diagnosed with PSSM by muscle histopathologic analysis are negative for the mutation. We hypothesized that a second distinct form of glycogen storage disease exists in GYS1-negative horses with PSSM. The objectives of this study were to compare the histopathologic features, ultrastructure of polysaccharide, signalment, history, and presenting complaints of GYS1-negative Quarter Horses and related breeds with PSSM to those of GYS1-positive horses with PSSM. The total histopathologic score in frozen sections of skeletal muscle stained with hematoxylin and eosin, periodic acid Schiff (PAS) and amylase-PAS stains from 53 GYS1-negative horses did not differ from that of 52 GYS1-positive horses. Abnormal polysaccharide was fine granular or homogenous in appearance (49/53; 92%), often amylase-sensitive (28/53; 53%), more commonly located under the sarcolemma, and consisting of beta glycogen particles in GYS1-negative horses. However, in GYS1-positive horses, abnormal polysaccharide was usually coarse granular (50/52; 96%), amylase-resistant (51/52; 98%), more commonly cytoplasmic, and consisting of beta glycogen particles or, in some myofibers, filamentous material surrounded by beta glycogen particles. Retrospective analysis found that GYS1-negative horses (n = 43) were younger at presentation (4.9 +/- 0.6 years vs. 6.7 +/- 0.3 years for GYS1-positive horses) and were more likely to be intact males than GYS1-positive horses (n = 160). We concluded that 2 forms of PSSM exist and often have distinctive abnormal polysaccharide. However, because evaluation of the histologic appearance of polysaccharide can be subjective and

  12. Building a Relationship between Elements of Product Form Features and Vocabulary Assessment Models

    ERIC Educational Resources Information Center

    Lo, Chi-Hung

    2016-01-01

    Based on the characteristic feature parameterization and the superiority evaluation method (SEM) in extension engineering, a product-shape design method was proposed in this study. The first step of this method is to decompose the basic feature components of a product. After that, the morphological chart method is used to segregate the ideas so as…

  13. Building a Relationship between Elements of Product Form Features and Vocabulary Assessment Models

    ERIC Educational Resources Information Center

    Lo, Chi-Hung

    2016-01-01

    Based on the characteristic feature parameterization and the superiority evaluation method (SEM) in extension engineering, a product-shape design method was proposed in this study. The first step of this method is to decompose the basic feature components of a product. After that, the morphological chart method is used to segregate the ideas so as…

  14. Function Follows Form: Activation of Shape and Function Features during Object Identification

    ERIC Educational Resources Information Center

    Yee, Eiling; Huffstetler, Stacy; Thompson-Schill, Sharon L.

    2011-01-01

    Most theories of semantic memory characterize knowledge of a given object as comprising a set of semantic features. But how does conceptual activation of these features proceed during object identification? We present the results of a pair of experiments that demonstrate that object recognition is a dynamically unfolding process in which function…

  15. Function Follows Form: Activation of Shape and Function Features during Object Identification

    ERIC Educational Resources Information Center

    Yee, Eiling; Huffstetler, Stacy; Thompson-Schill, Sharon L.

    2011-01-01

    Most theories of semantic memory characterize knowledge of a given object as comprising a set of semantic features. But how does conceptual activation of these features proceed during object identification? We present the results of a pair of experiments that demonstrate that object recognition is a dynamically unfolding process in which function…

  16. Methods for the Precise Locating and Forming of Arrays of Curved Features into a Workpiece

    DOEpatents

    Gill, David Dennis; Keeler, Gordon A.; Serkland, Darwin K.; Mukherjee, Sayan D.

    2008-10-14

    Methods for manufacturing high precision arrays of curved features (e.g. lenses) in the surface of a workpiece are described utilizing orthogonal sets of inter-fitting locating grooves to mate a workpiece to a workpiece holder mounted to the spindle face of a rotating machine tool. The matching inter-fitting groove sets in the workpiece and the chuck allow precisely and non-kinematically indexing the workpiece to locations defined in two orthogonal directions perpendicular to the turning axis of the machine tool. At each location on the workpiece a curved feature can then be on-center machined to create arrays of curved features on the workpiece. The averaging effect of the corresponding sets of inter-fitting grooves provide for precise repeatability in determining, the relative locations of the centers of each of the curved features in an array of curved features.

  17. Androgen levels in women with various forms of ovarian dysfunction: associations with cardiometabolic features.

    PubMed

    Daan, N M P; Jaspers, L; Koster, M P H; Broekmans, F J M; de Rijke, Y B; Franco, O H; Laven, J S E; Kavousi, M; Fauser, B C J M

    2015-10-01

    Are differences in androgen levels among women with various forms of ovarian dysfunction associated with cardiometabolic abnormalities? Androgen levels differed substantially between women with and without ovarian dysfunction, and increased androgen levels were associated with impaired cardiometabolic features in all women irrespective of their clinical condition. Sex steroid hormones play important roles in the development of cardiovascular diseases (CVD). Extremes of low as well as high androgen levels have been associated with increased CVD risk in both men and women. This cross-sectional study included 680 women with polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI), natural post-menopausal women (NM), or regular menstrual cycles (RC) (170 women per group). Measurements of serum testosterone, androstenedione and dehydroepiandrosterone sulfate were performed using liquid chromatography-tandem mass spectrometry. Assessments were taken of body mass index (BMI), blood pressure, lipid profiles, glucose, insulin and SHBG, and the bioactive fraction of circulating testosterone was calculated using the free androgen index (FAI). PCOS women were hyperandrogenic [median FAI = 4.9 (IQR 3.6-7.4)], and POI women were hypoandrogenic [FAI = 1.2 (0.8-1.7)], compared with RC women [FAI = 1.7 (1.1-2.8)], after adjustment for age, ethnicity, smoking and BMI (P < 0.001). After adjustment for age, there were no significant differences in androgens between POI and NM (P = 0.15) women and between NM and RC (P = 0.27) women, the latter indicating that chronological aging rather than ovarian aging influences the differences between pre- and post-menopausal women. A high FAI was associated with elevated triglycerides (β log FAI for PCOS: 0.45, P < 0.001, POI: 0.25, P < 0.001, NM: 0.20, P = 0.002), insulin (β log FAI for PCOS: 0.77, POI: 0.44, NM: 0.40, all P < 0.001), HOMA-IR (β log FAI for PCOS: 0.82, POI: 0.46, NM: 0.47, all P < 0.001) and mean arterial

  18. Can two dots form a Gestalt? Measuring emergent features with the capacity coefficient.

    PubMed

    Hawkins, Robert X D; Houpt, Joseph W; Eidels, Ami; Townsend, James T

    2016-09-01

    While there is widespread agreement among vision researchers on the importance of some local aspects of visual stimuli, such as hue and intensity, there is no general consensus on a full set of basic sources of information used in perceptual tasks or how they are processed. Gestalt theories place particular value on emergent features, which are based on the higher-order relationships among elements of a stimulus rather than local properties. Thus, arbitrating between different accounts of features is an important step in arbitrating between local and Gestalt theories of perception in general. In this paper, we present the capacity coefficient from Systems Factorial Technology (SFT) as a quantitative approach for formalizing and rigorously testing predictions made by local and Gestalt theories of features. As a simple, easily controlled domain for testing this approach, we focus on the local feature of location and the emergent features of Orientation and Proximity in a pair of dots. We introduce a redundant-target change detection task to compare our capacity measure on (1) trials where the configuration of the dots changed along with their location against (2) trials where the amount of local location change was exactly the same, but there was no change in the configuration. Our results, in conjunction with our modeling tools, favor the Gestalt account of emergent features. We conclude by suggesting several candidate information-processing models that incorporate emergent features, which follow from our approach. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. The influence of nanostructured features on bacterial adhesion and bone cell functions on severely shot peened 316L stainless steel.

    PubMed

    Bagherifard, Sara; Hickey, Daniel J; de Luca, Alba C; Malheiro, Vera N; Markaki, Athina E; Guagliano, Mario; Webster, Thomas J

    2015-12-01

    Substrate grain structure and topography play major roles in mediating cell and bacteria activities. Severe plastic deformation techniques, known as efficient metal-forming and grain refining processes, provide the treated material with novel mechanical properties and can be adopted to modify nanoscale surface characteristics, possibly affecting interactions with the biological environment. This in vitro study evaluates the capability of severe shot peening, based on severe plastic deformation, to modulate the interactions of nanocrystallized metallic biomaterials with cells and bacteria. The treated 316L stainless steel surfaces were first investigated in terms of surface topography, grain size, hardness, wettability and residual stresses. The effects of the induced surface modifications were then separately studied in terms of cell morphology, adhesion and proliferation of primary human osteoblasts (bone forming cells) as well as the adhesion of multiple bacteria strains, specifically Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and ampicillin-resistant Escherichia coli. The results indicated a significant enhancement in surface work hardening and compressive residual stresses, maintenance of osteoblast adhesion and proliferation as well as a remarkable decrease in the adhesion and growth of gram-positive bacteria (S. aureus and S. epidermidis) compared to non-treated and conventionally shot peened samples. Impressively, the decrease in bacteria adhesion and growth was achieved without the use of antibiotics, for which bacteria can develop a resistance towards anyway. By slightly grinding the surface of severe shot peened samples to remove differences in nanoscale surface roughness, the effects of varying substrate grain size were separated from those of varying surface roughness. The expression of vinculin focal adhesions from osteoblasts was found to be singularly and inversely related to grain size, whereas the attachment of gram

  20. Transcontinental arch - a pattern formed by rejuvenation of local features across central North America

    USGS Publications Warehouse

    Carlson, M.P.

    1999-01-01

    The transcontinental Arch has been described by many authors as a feature having significant tectonic influence during the Phanerozoic, although the location, magnitude, and even the timing defining the arch vary greatly among authors. The general trend usually suggested for the Transcontinental Arch is northeast-southwest across the western midcontinent of North America. A series of isopachous and paleogeologic maps was compiled for this study that defines a number of smaller tectonic features - commonly trending northwest-southeast. Six persistent highs and six persistent lows (or sags) are defined that are largely basement controlled and were rejuvenated at various times during the Phanerozoic. These smaller northwest-trending features, when taken collectively and enhanced by the relative downwarping of the adjacent Williston and Anadarko basins, create a platform-like feature - the Transcontinental Arch of the literature. The concept of a Transcontinental Arch is an important reference trend in the geologic history of North America. In both regional and local studies, however, the smaller-scale, transverse features may have had significant control on both tectonic patterns and depositional influence.

  1. Properties of a photonic crystal formed in a solution featuring the Briggs-Rauscher oscillating reaction

    NASA Astrophysics Data System (ADS)

    Usanov, D. A.; Rytik, A. P.

    2016-06-01

    It is shown that a solution featuring the Briggs-Rauscher (BR) oscillating chemical reaction can exhibit the properties of a photonic crystal with alternating bandgap width. Thicknesses and dielectric permittivities of structural elements in the BR reaction solution have been determined by measuring the reflection and transmission spectra of microwave radiation in the range of 5-8 GHz.

  2. The Role of Eolian Processes in Forming Surface Features of the Martian Polar Layered Deposits

    NASA Astrophysics Data System (ADS)

    Howard, Alan D.

    2000-04-01

    The major topographic features of the martian polar layered deposits include the conspicuous spiral troughs, subtle undulations, broad reentrants (chasma), steep, arcuate scarps, and dune fields. A prominent role for eolian processes in the formation of all of these features is proposed. Strong katabatic winds occur on the north polar cap, producing widespread frost streaks. These cold drainage winds are analogous to those on the terrestrial Antarctic cap. In the chasmae convergent katabatic winds create yardangs and erode arcuate scarps in the layered deposits that are also the source for local dune fields migrating outward from the polar cap. The chasmae are postulated to originate by long-term erosion by katabatic wind. Wind plays a role in formation of the troughs and scarps primarily through removal of dust freed from exposed layered deposits by ablation of ice on defrosted equator-facing slopes. The undulations are created by interaction between surface erosion or deposition of perennial ice and standing waves in the shallow katabatic windflow. The south polar layered deposits exhibit topographic features similar to those at the north polar cap, but erosion and depositional processes creating these features may be inactive during the current epoch because of the lack of an extensive perennial ice cover and associated katabatic wind.

  3. Tuning of structural, light emission and wetting properties of nanostructured copper oxide-porous silicon matrix formed on electrochemically etched copper-coated silicon substrates

    NASA Astrophysics Data System (ADS)

    Naddaf, M.

    2017-01-01

    Matrices of copper oxide-porous silicon nanostructures have been formed by electrochemical etching of copper-coated silicon surfaces in HF-based solution at different etching times (5-15 min). Micro-Raman, X-ray diffraction and X-ray photoelectron spectroscopy results show that the nature of copper oxide in the matrix changes from single-phase copper (I) oxide (Cu2O) to single-phase copper (II) oxide (CuO) on increasing the etching time. This is accompanied with important variation in the content of carbon, carbon hydrides, carbonyl compounds and silicon oxide in the matrix. The matrix formed at the low etching time (5 min) exhibits a single broad "blue" room-temperature photoluminescence (PL) band. On increasing the etching time, the intensity of this band decreases and a much stronger "red" PL band emerges in the PL spectra. The relative intensity of this band with respect to the "blue" band significantly increases on increasing the etching time. The "blue" and "red" PL bands are attributed to Cu2O and porous silicon of the matrix, respectively. In addition, the water contact angle measurements reveal that the hydrophobicity of the matrix surface can be tuned from hydrophobic to superhydrophobic state by controlling the etching time.

  4. Shape controllable synthesis of ZnCdS 1-D nanostructures formed on ITO/glass by using the co-evaporation method

    NASA Astrophysics Data System (ADS)

    Lee, Dong Jin; Jeon, Hee Chang; Yuldashev, Shavkat; Kang, Tae Won; Ryu, Sung Ryong; Son, Moon A.; Park, Ji Won; Woo, Yong Deuk

    2015-01-01

    Self-assembled, one dimensional (1-D) Zn1- x Cd x S nanostructures with a Cd composition of x = 0.11 have been successfully fabricated on indium-tin-oxide/glass substrates by using a co-evaporation method in the absence of any catalyst. The structures and the morphologies of these nanostructures were studied using X-ray diffraction and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy confirmed that the Cd ions occupied the Zn sites in the ZnCdS nanowire. The fabricated ZnCdS nanostructures exhibited various shapes, such as hexagonal nanorods (H-NRs), cylindrical nanorods (C-NRs), nanoneedles (NNs), nanowires (NWs) and nanodumbbells (NDs), for different substrate temperatures. Increasing the substrate temperature resulted in the formation of nanostructures with smaller diameters. The shape-controllable growth of ZnCdS 1-D nanostructures might result in the development of a high-efficiency nano-solar cell.

  5. Classifying Glioblastoma Multiforme Follow-Up Progressive vs. Responsive Forms Using Multi-Parametric MRI Features

    PubMed Central

    Ion-Mărgineanu, Adrian; Van Cauter, Sofie; Sima, Diana M.; Maes, Frederik; Sunaert, Stefan; Himmelreich, Uwe; Van Huffel, Sabine

    2017-01-01

    Purpose: The purpose of this paper is discriminating between tumor progression and response to treatment based on follow-up multi-parametric magnetic resonance imaging (MRI) data retrieved from glioblastoma multiforme (GBM) patients. Materials and Methods: Multi-parametric MRI data consisting of conventional MRI (cMRI) and advanced MRI [i.e., perfusion weighted MRI (PWI) and diffusion kurtosis MRI (DKI)] were acquired from 29 GBM patients treated with adjuvant therapy after surgery. We propose an automatic pipeline for processing advanced MRI data and extracting intensity-based histogram features and 3-D texture features using manually and semi-manually delineated regions of interest (ROIs). Classifiers are trained using a leave-one-patient-out cross validation scheme on complete MRI data. Balanced accuracy rate (BAR)–values are computed and compared between different ROIs, MR modalities, and classifiers, using non-parametric multiple comparison tests. Results: Maximum BAR–values using manual delineations are 0.956, 0.85, 0.879, and 0.932, for cMRI, PWI, DKI, and all three MRI modalities combined, respectively. Maximum BAR–values using semi-manual delineations are 0.932, 0.894, 0.885, and 0.947, for cMRI, PWI, DKI, and all three MR modalities combined, respectively. After statistical testing using Kruskal-Wallis and post-hoc Dunn-Šidák analysis we conclude that training a RUSBoost classifier on features extracted using semi-manual delineations on cMRI or on all MRI modalities combined performs best. Conclusions: We present two main conclusions: (1) using T1 post-contrast (T1pc) features extracted from manual total delineations, AdaBoost achieves the highest BAR–value, 0.956; (2) using T1pc-average, T1pc-90th percentile, and Cerebral Blood Volume (CBV) 90th percentile extracted from semi-manually delineated contrast enhancing ROIs, SVM-rbf, and RUSBoost achieve BAR–values of 0.947 and 0.932, respectively. Our findings show that AdaBoost, SVM-rbf, and

  6. Modeling of semi-shell nanostructures formed by metal deposition on dielectric nanospheres and numerical evaluation of plasmonic properties

    NASA Astrophysics Data System (ADS)

    Fujimura, Ryushi; Zhang, Ruzhi; Kitamoto, Yoshitaka; Shimojo, Masayuki; Kajikawa, Kotaro

    2014-03-01

    A theoretical model of semi-shell structures formed by metal deposition is constructed for accurate prediction of plasmonic properties. Our model takes account of the influence of metal migration after deposition and the granular nature of the metal. Validity of our model was confirmed by the fact that the plasmonic resonances simulated by our model agreed well with those obtained by experiment. Simulations using the discrete dipole approximation revealed that the semi-shells formed by metal deposition show a larger absorption cross-section than semi-shells fabricated by reshaping of fully-covered core-shells. The deposition type semi-shell is suitable for the photothermal therapy because a larger temperature rise is expected due to greater absorption.

  7. SPATIALLY RESOLVED POLYCYCLIC AROMATIC HYDROCARBON EMISSION FEATURES IN NEARBY, LOW METALLICITY, STAR-FORMING GALAXIES

    SciTech Connect

    Haynes, Korey; Cannon, John M.; Skillman, Evan D.; Gehrz, Robert; Jackson, Dale C. E-mail: khaynes5@gmu.ed E-mail: gehrz@astro.umn.ed

    2010-11-20

    Low-resolution, mid-infrared Spitzer/IRS spectral maps are presented for three nearby, low-metallicity dwarf galaxies (NGC 55, NGC 3109, and IC 5152) for the purpose of examining the spatial distribution and variation of polycyclic aromatic hydrocarbon (PAH) emission. The sample straddles a metallicity of 12 + log(O/H) {approx} 8, a transition point below which PAH intensity empirically drops and the character of the interstellar medium changes. We derive quantitative radiances of PAH features and atomic lines on both global and spatially resolved scales. The Spitzer spectra, combined with extensive ancillary data from the UV through the mid-infrared, allow us to examine changes in the physical environments and in PAH feature radiances down to a physical scale of {approx}50 pc. We discuss correlations between various PAH emission feature and atomic line radiances. The (6.2 {mu}m)/(11.3 {mu}m), (7.7 {mu}m)/(11.3 {mu}m), (8.6 {mu}m)/(11.3 {mu}m), (7.7 {mu}m)/(6.2 {mu}m), and (8.6 {mu}m)/(6.2 {mu}m) PAH radiance ratios are found to be independent of position across all three galaxies, although the ratios do vary from galaxy to galaxy. As seen in other galaxies, we find no variation in the grain size distribution as a function of local radiation field strength. Absolute PAH feature intensities as measured by a ratio of PAH/(24 {mu}m) radiances are seen to vary both positionally within a given galaxy and from one galaxy to another when integrated over the full observed extent of each system. We examine direct comparisons of CC mode PAH ratios (7.7 {mu}m)/(6.2 {mu}m) and (8.6 {mu}m)/(6.2 {mu}m) to the mixed (CC/CH) mode PAH ratio (7.7 {mu}m)/(11.3 {mu}m). We find little variation in either mode and no difference in trends between modes. While the local conditions change markedly over the observed regions of these galaxies, the properties of PAH emission show a remarkable degree of uniformity.

  8. Complex WS 2 nanostructures

    NASA Astrophysics Data System (ADS)

    Whitby, R. L. D.; Hsu, W. K.; Lee, T. H.; Boothroyd, C. B.; Kroto, H. W.; Walton, D. R. M.

    2002-06-01

    A range of elegant tubular and conical nanostructures has been created by template growth of (WS 2) n layers on the surfaces of single-walled carbon nanotube bundles. The structures exhibit remarkably perfect straight segments together with interesting complexities at the intersections, which are discussed here in detail in order to enhance understanding of the structural features governing tube growth.

  9. Light-emitting Si nanostructures formed by swift heavy ions in a-Si:H/SiO2 multilayer heterostructures

    NASA Astrophysics Data System (ADS)

    Cherkova, S. G.; Volodin, V. A.; Cherkov, A. G.; Antonenko, A. Kh; Kamaev, G. N.; Skuratov, V. A.

    2017-08-01

    Light-emitting nanoclusters were formed in Si/SiO2 multilayer structures irradiated with 167 MeV Xe ions to the doses of 1011-3  ×  1014 cm-2 and annealed in the forming-gas at 500 °C and in nitrogen at 800-1100 °C, 30 min. The thicknesses were ~4 nm or ~7-8 for the Si, and ~10 nm for the SiO2 layers. The structures were studied using photoluminescence (PL), Raman spectroscopy, and the cross-sectional high resolution transmission electron microscopy (HRTEM). As-irradiated samples showed the PL, correlating with the growth of the ion doses. HRTEM found the layers to be partly disintegrated. The thickness of the amorphous Si layer was crucial. For 4 nm thick Si layers the PL was peaking at ~490 nm, and quenched by the annealing. It was ascribed to the structural imperfections. For the thicker Si layers the PL was peaking at ~600 nm and was attributed to the Si-rich nanoclusters in silicon oxide. The annealing increases the PL intensity and shifts the band to ~790 nm, typical of Si nanocrystals. Its intensity was proportional to the dose. Raman spectra confirmed the nanocrystals formation. All the results obtained evidence the material melting in the tracks for 10-11-10-10 s providing thereby fast diffusivities of the atoms. The thicker Si layers provide more excess Si to create the nanoclusters via a molten state diffusion.

  10. Investigation of influence of friction stir welding regimes on the features of mass transfer and temperature distribution in forming welds

    NASA Astrophysics Data System (ADS)

    Astafurov, S. V.; Shilko, E. V.; Kolubaev, E. A.; Psakhie, S. G.

    2015-10-01

    Computer simulation by the movable cellular automaton method was performed to study the influence of friction stir welding regimes on the features of intensive mass transfer and temperature distribution in forming welded joints. The calculation results showed that there is a range of optimal values of the ratio of the angular velocity to the welding speed which provides sufficient mass transfer to form a welded joint with a minimum volume content of defects. The use of the optimal FSW regimes allows to obtain joints without significant overheating of the welded materials.

  11. Formation of different gold nanostructures by silk nanofibrils.

    PubMed

    Fang, Guangqiang; Yang, Yuhong; Yao, Jinrong; Shao, Zhengzhong; Chen, Xin

    2016-07-01

    Metal nanostructures that have unique size- and shape-dependent electronic, optical and chemical properties gain more and more attention in modern science and technology. In this article, we show the possibility that we are able to obtain different gold nanostructures simply with the help of silk nanofibrils. We demonstrate that only by varying the pH of the reaction solution, we get gold nanoparticles, nano-icosahedrons, nanocubes, and even microplates. Particularly, we develop a practical method for the preparation of gold microplates in acid condition in the presence of silk nanofibrils, which is impossible by using other forms of silk protein. We attribute the role of silk nanofibrils in the formation of gold nanostructure to their reduction ability from several specific amino acid residues, and the suitable structural anisotropic features to sustain the crystal growth after the reduction process. Although the main purpose of this article is to demonstrate that silk nanofibrils are able to mediate the formation of different gold nanostructure, we show the potential applications of these resulting gold nanostructures, such as surface-enhanced Raman scattering (SERS) and photothermal transformation effect, as same as those produced by other methods. In conclusion, we present in this communication a facile and green synthesis route to prepare various gold nanostructures with silk nanofibrils by simply varying pH in the reaction system, which has remarkable advantages in future biomedical applications.

  12. Method of fabrication of anchored nanostructure materials

    DOEpatents

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2013-11-26

    Methods for fabricating anchored nanostructure materials are described. The methods include heating a nano-catalyst under a protective atmosphere to a temperature ranging from about 450.degree. C. to about 1500.degree. C. and contacting the heated nano-catalysts with an organic vapor to affix carbon nanostructures to the nano-catalysts and form the anchored nanostructure material.

  13. Nanostructured materials in electroanalysis of pharmaceuticals.

    PubMed

    Rahi, A; Karimian, K; Heli, H

    2016-03-15

    Basic strategies and recent developments for the enhancement of the sensory performance of nanostructures in the electroanalysis of pharmaceuticals are reviewed. A discussion of the properties of nanostructures and their application as modified electrodes for drug assays is presented. The electrocatalytic effect of nanostructured materials and their application in determining low levels of drugs in pharmaceutical forms and biofluids are discussed.

  14. Structure and Optical Features of Micro/Nanosized Carbon Forms Prepared by Electrochemical Exfoliation

    NASA Astrophysics Data System (ADS)

    Nedilko, Sergii G.; Revo, Sergiy; Chornii, Vitalii; Scherbatskyi, Vasyl; Ivanenko, Kateryna; Nedielko, Maksym; Sementsov, Yurii; Skoryk, Mykola; Nikolenko, Andrii; Strelchuk, Victor

    2017-01-01

    Micro/nanosized carbon materials were prepared by electrochemical exfoliation method in the forms of the colloids and thin films. Scanning electronic microscopy, optical and luminescent microscopy, and Raman scattering and luminescent spectroscopy were applied for characterization of materials. The wide photoluminescence band in the visible spectral region was observed for each of the samples. The shape of the photoluminescence band depends on excitation wavelength and on the size of the particles. At least two components with maxima at 580 and 710 nm can be distinguished in the photoluminescence spectra. The relations between the photoluminescence properties and morphology of the samples have been described and discussed.

  15. Special features in the electroreduction of oxidic molybdenum(VI) forms in tungstate melt

    SciTech Connect

    Shapoval, V.I.; Baraboshkin, A.N.; Kushkhov, K.B.; Malyshev, V.V.

    1988-01-01

    The electrochemical behavior of oxidic molybdenum in tungstate melt was studied under equilibrium and nonequilibrium conditions. Chronovoltammetry and transient polarization was used. The current-voltage curves were recorded with a pulse potentiostat and the experiments were performed in a quartz reactor with platinum and molybdenum electrodes and a platinum crucible served as the melt container and anode. The end product of the oxidic molybdenum forms were shown to depend on the acid-base properties of the melt which allows for choosing the properties and controlling the electrode process.

  16. Generation Mechanism and Propagation Features of the Ionospheric Weather Forming ULF Electromagnetic Wave Structures

    NASA Astrophysics Data System (ADS)

    Aburjania, G. D.; Chargazia, Kh. Z.; Khantadze, A. G.; Lominadze, J. G.

    2006-12-01

    Results of theoretical investigation of the dynamics of generation and propagation of planetary (with wavelengths 103 km and more) weather-forming Ultra-Low Frequency (ULF) electromagnetic wave structures in the dissipative ionosphere are given in this paper. It is established that the global factor, acting permanently in the ionosphere spatial inhomogeneity and curvature of the geomagnetic field and inhomogeneity of angular velocity of the Earth's rotation generates the fast and slow planetary ULF electromagnetic waves. The waves propagate along the parallels to the east as well as to the west. In the E-region the fast waves have phase velocities of (2-20) km/s-1 and frequencies of (10^-1-10^-4) Hz; the slow waves propagate with local wind velocities and have frequencies (10^-4-10^-6) Hz. In the F-region the fast ULF electromagnetic waves propagate with phase velocities of tens-hundreds km/s-1 and their frequencies are in the range of (10-10^-3) Hz. The large-scale waves are weakly damped. The waves generate the geomagnetic field perturbations from several tens to several hundreds nT and more. It is established that planetary ULF electromagnetic waves, at their interaction with the local shear winds, can self-localize in the form of nonlinear solitary vortices, moving along the latitude circles westward as well as eastward.

  17. Direct observation of melting behaviors at the nanoscale under electron beam and heat to form hollow nanostructures.

    PubMed

    Huang, Chun-Wei; Hsin, Cheng-Lun; Wang, Chun-Wen; Chu, Fu-Hsuan; Kao, Chen-Yen; Chen, Jui-Yuan; Huang, Yu-Ting; Lu, Kuo-Chang; Wu, Wen-Wei; Chen, Lih-Juann

    2012-08-07

    We report the melting behaviours of ZnO nanowire by heating ZnO-Al(2)O(3) core-shell heterostructures to form Al(2)O(3) nanotubes in an in situ ultrahigh vacuum transmission electron microscope (UHV-TEM). When the ZnO-Al(2)O(3) core-shell nanowire heterostructures were annealed at 600 °C under electron irradiation, the amorphous Al(2)O(3) shell became single crystalline and then the ZnO core melted. The average vanishing rate of the ZnO core was measured to be 4.2 nm s(-1). The thickness of the Al(2)O(3) nanotubes can be precisely controlled by the deposition process. Additionally, the inner geometry of nanotubes can be defined by the initial ZnO core. The result shows a promising method to obtain the biocompatible Al(2)O(3) nanotubes, which may be applied in drug delivery, biochemistry and resistive switching random access memory (ReRAM).

  18. Thermodynamic Features of Structural Motifs Formed by β-L-RNA

    PubMed Central

    Szabat, Marta; Gudanis, Dorota; Kotkowiak, Weronika; Gdaniec, Zofia; Kierzek, Ryszard; Pasternak, Anna

    2016-01-01

    This is the first report to provide comprehensive thermodynamic and structural data concerning duplex, hairpin, quadruplex and i-motif structures in β-L-RNA series. Herein we confirm that, within the limits of experimental error, the thermodynamic stability of enantiomeric structural motifs is the same as that of naturally occurring D-RNA counterparts. In addition, formation of D-RNA/L-RNA heterochiral duplexes is also observed; however, their thermodynamic stability is significantly reduced in reference to homochiral D-RNA duplexes. The presence of three locked nucleic acid (LNA) residues within the D-RNA strand diminishes the negative effect of the enantiomeric, complementary L-RNA strand in the formation of heterochiral RNA duplexes. Similar behavior is also observed for heterochiral LNA-2′-O-methyl-D-RNA/L-RNA duplexes. The formation of heterochiral duplexes was confirmed by 1H NMR spectroscopy. The CD curves of homochiral L-RNA structural motifs are always reversed, whereas CD curves of heterochiral duplexes present individual features dependent on the composition of chiral strands. PMID:26908023

  19. Form features provide a cue to the angular velocity of rotating objects

    PubMed Central

    Blair, Christopher David; Goold, Jessica; Killebrew, Kyle; Caplovitz, Gideon Paul

    2013-01-01

    As an object rotates, each location on the object moves with an instantaneous linear velocity dependent upon its distance from the center of rotation, while the object as a whole rotates with a fixed angular velocity. Does the perceived rotational speed of an object correspond to its angular velocity, linear velocities, or some combination of the two? We had observers perform relative speed judgments of different sized objects, as changing the size of an object changes the linear velocity of each location on the object’s surface, while maintaining the object’s angular velocity. We found that the larger a given object is, the faster it is perceived to rotate. However, the observed relationships between size and perceived speed cannot be accounted for simply by size-related changes in linear velocity. Further, the degree to which size influences perceived rotational speed depends on the shape of the object. Specifically, perceived rotational speeds of objects with corners or regions of high contour curvature were less affected by size. The results suggest distinct contour features, such as corners or regions of high or discontinuous contour curvature, provide cues to the angular velocity of a rotating object. PMID:23750970

  20. Form features provide a cue to the angular velocity of rotating objects.

    PubMed

    Blair, Christopher David; Goold, Jessica; Killebrew, Kyle; Caplovitz, Gideon Paul

    2014-02-01

    As an object rotates, each location on the object moves with an instantaneous linear velocity, dependent upon its distance from the center of rotation, whereas the object as a whole rotates with a fixed angular velocity. Does the perceived rotational speed of an object correspond to its angular velocity, linear velocities, or some combination of the two? We had observers perform relative speed judgments of different-sized objects, as changing the size of an object changes the linear velocity of each location on the object's surface, while maintaining the object's angular velocity. We found that the larger a given object is, the faster it is perceived to rotate. However, the observed relationships between size and perceived speed cannot be accounted for simply by size-related changes in linear velocity. Further, the degree to which size influences perceived rotational speed depends on the shape of the object. Specifically, perceived rotational speeds of objects with corners or regions of high-contour curvature were less affected by size. The results suggest distinct contour features, such as corners or regions of high or discontinuous contour curvature, provide cues to the angular velocity of a rotating object.

  1. Extrastriate Visual Areas Integrate Form Features over Space and Time to Construct Representations of Stationary and Rigidly Rotating Objects.

    PubMed

    McCarthy, J Daniel; Kohler, Peter J; Tse, Peter U; Caplovitz, Gideon Paul

    2015-11-01

    When an object moves behind a bush, for example, its visible fragments are revealed at different times and locations across the visual field. Nonetheless, a whole moving object is perceived. Unlike traditional modal and amodal completion mechanisms known to support spatial form integration when all parts of a stimulus are simultaneously visible, relatively little is known about the neural substrates of the spatiotemporal form integration (STFI) processes involved in generating coherent object representations from a succession visible fragments. We used fMRI to identify brain regions involved in two mechanisms supporting the representation of stationary and rigidly rotating objects whose form features are shown in succession: STFI and position updating. STFI allows past and present form cues to be integrated over space and time into a coherent object even when the object is not visible in any given frame. STFI can occur whether or not the object is moving. Position updating allows us to perceive a moving object, whether rigidly rotating or translating, even when its form features are revealed at different times and locations in space. Our results suggest that STFI is mediated by visual regions beyond V1 and V2. Moreover, although widespread cortical activation has been observed for other motion percepts derived solely from form-based analyses [Tse, P. U. Neural correlates of transformational apparent motion. Neuroimage, 31, 766-773, 2006; Krekelberg, B., Vatakis, A., & Kourtzi, Z. Implied motion from form in the human visual cortex. Journal of Neurophysiology, 94, 4373-4386, 2005], increased responses for the position updating that lead to rigidly rotating object representations were only observed in visual areas KO and possibly hMT+, indicating that this is a distinct and highly specialized type of processing.

  2. Extrastriate visual areas integrate form features over space and time to construct representations of stationary and rigidly rotating objects

    PubMed Central

    McCarthy, J. Daniel; Kohler, Peter J.; Tse, Peter U.; Caplovitz, Gideon Paul

    2016-01-01

    When an object moves behind a bush, for example, its visible fragments are revealed at different times and locations across the visual field. Nonetheless, a whole moving object is perceived. Unlike traditional modal and amodal completion mechanisms known to support spatial form integration when all parts of a stimulus are simultaneously visible, relatively little is known about the neural substrates of the spatiotemporal form integration processes involved in generating coherent object representations from a succession visible fragments. We use fMRI to identify brain regions involved in two mechanisms supporting the representation of stationary and rigidly rotating objects whose form features are shown in succession: Spatiotemporal Form Integration (STFI) and Position Updating. STFI allows past and present form cues to be integrated over space and time into a coherent object even when the object is not visible in any given frame. STFI can occur whether or not the object is moving. Position updating allows us to perceive a moving object, whether rigidly rotating or translating, even when its form features are revealed at different times and locations in space. Our results suggest that STFI is mediated by visual regions beyond V1 and V2. Moreover, while widespread cortical activation has been observed for other motion percepts derived solely from form-based analyses (Krekelberg, Vatakis, & Kourtzi, 2005; Tse, 2006), increased responses for the position updating that leads to rigidly rotating object representations were only observed in visual areas KO and possibly hMT+, indicating that this is a distinct and highly specialized type of processing. PMID:26226075

  3. Membranous glomerulonephritis: histological and serological features to differentiate cancer-related and non-related forms.

    PubMed

    Murtas, Corrado; Ghiggeri, Gian Marco

    2016-08-01

    Membranous nephropathy is a frequent cause of nephrotic syndrome in adults. In most patients, it appears as a primary renal disease but in about 20 % of cases membranous nephropathy is associated with systemic conditions such as systemic lupus erythematosus, infections or cancer, or with drug exposure. Reliable differentiation between primary and secondary membranous nephropathy has important implications for the patient, because of different therapeutic approaches between the different forms. The recent in vivo definition of glomerular targets of autoimmunity in idiopathic membranous nephropathy represented a real breakthrough and nowadays more than one podocyte antigen is considered in some way implicated in the pathogenesis of human membranous nephropathy. Specific antibodies against all these components have been detected in serum of patients and could become biomarkers of membranous nephropathy and/or of disease activity. In this brief review, we discuss the usefulness of newly described autoantibodies in the differential diagnosis of secondary membranous nephropathy. Histological clues for recognizing the two pathological entities are also analysed with regard to the available scientific evidence on this issue. Our evaluation shows that more research is needed to identify the best approach to reach a correct diagnosis of primary or secondary membranous nephropathy.

  4. Reactor and method for production of nanostructures

    DOEpatents

    Sunkara, Mahendra Kumar; Kim, Jeong H.; Kumar, Vivekanand

    2017-04-25

    A reactor and method for production of nanostructures, including metal oxide nanowires or nanoparticles, are provided. The reactor includes a regulated metal powder delivery system in communication with a dielectric tube; a plasma-forming gas inlet, whereby a plasma-forming gas is delivered substantially longitudinally into the dielectric tube; a sheath gas inlet, whereby a sheath gas is delivered into the dielectric tube; and a microwave energy generator coupled to the dielectric tube, whereby microwave energy is delivered into a plasma-forming gas. The method for producing nanostructures includes providing a reactor to form nanostructures and collecting the formed nanostructures, optionally from a filter located downstream of the dielectric tube.

  5. Structure and spectral features of H+(H2O)7: Eigen versus Zundel forms

    NASA Astrophysics Data System (ADS)

    Shin, Ilgyou; Park, Mina; Min, Seung Kyu; Lee, Eun Cheol; Suh, Seung Bum; Kim, Kwang S.

    2006-12-01

    The two dimensional (2D) to three dimensional (3D) transition for the protonated water cluster has been controversial, in particular, for H+(H2O)7. For H+(H2O)7 the 3D structure is predicted to be lower in energy than the 2D structure at most levels of theory without zero-point energy (ZPE) correction. On the other hand, with ZPE correction it is predicted to be either 2D or 3D depending on the calculational levels. Although the ZPE correction favors the 3D structure at the level of coupled cluster theory with singles, doubles, and perturbative triples excitations [CCSD(T)] using the aug-cc-pVDZ basis set, the result based on the anharmonic zero-point vibrational energy correction favors the 2D structure. Therefore, the authors investigated the energies based on the complete basis set limit scheme (which we devised in an unbiased way) at the resolution of the identity approximation Møller-Plesset second order perturbation theory and CCSD(T) levels, and found that the 2D structure has the lowest energy for H+(H2O)7 [though nearly isoenergetic to the 3D structure for D+(D2O)7]. This structure has the Zundel-type configuration, but it shows the quantum probabilistic distribution including some of the Eigen-type configuration. The vibrational spectra of MP2/aug-cc-pVDZ calculations and Car-Parrinello molecular dynamics simulations, taking into account the thermal and dynamic effects, show that the 2D Zundel-type form is in good agreement with experiments.

  6. Controlled placement and orientation of nanostructures

    DOEpatents

    Zettl, Alex K; Yuzvinsky, Thomas D; Fennimore, Adam M

    2014-04-08

    A method for controlled deposition and orientation of molecular sized nanoelectromechanical systems (NEMS) on substrates is disclosed. The method comprised: forming a thin layer of polymer coating on a substrate; exposing a selected portion of the thin layer of polymer to alter a selected portion of the thin layer of polymer; forming a suspension of nanostructures in a solvent, wherein the solvent suspends the nanostructures and activates the nanostructures in the solvent for deposition; and flowing a suspension of nanostructures across the layer of polymer in a flow direction; thereby: depositing a nanostructure in the suspension of nanostructures only to the selected portion of the thin layer of polymer coating on the substrate to form a deposited nanostructure oriented in the flow direction. By selectively employing portions of the method above, complex NEMS may be built of simpler NEMSs components.

  7. Bottom-up multiferroic nanostructures

    NASA Astrophysics Data System (ADS)

    Ren, Shenqiang

    Multiferroic and especially magnetoelectric (ME) nanocomposites have received extensive attention due to their potential applications in spintronics, information storage and logic devices. The extrinsic ME coupling in composites is strain mediated via the interface between the piezoelectric and magnetostrictive components. However, the design and synthesis of controlled nanostructures with engineering enhanced coupling remain a significant challenge. The purpose of this thesis is to create nanostructures with very large interface densities and unique connectivities of the two phases in a controlled manner. Using inorganic solid state phase transformations and organic block copolymer self assembly methodologies, we present novel self assembly "bottom-up" techniques as a general protocol for the nanofabrication of multifunctional devices. First, Lead-Zirconium-Titanate/Nickel-Ferrite (PZT/NFO) vertical multilamellar nanostructures have been produced by crystallizing and decomposing a gel in a magnetic field below the Curie temperature of NFO. The ensuing microstructure is nanoscopically periodic and anisotropic. The wavelength of the PZT/NFO alternation, 25 nm, agrees within a factor of two with the theoretically estimated value. The macroscopic ferromagnetic and magnetoelectric responses correspond qualitatively and semi-quantitatively to the features of the nanostructure. The maximum of the field dependent magnetoelectric susceptibility equals 1.8 V/cm Oe. Second, a magnetoelectric composite with controlled nanostructures is synthesized using co-assembly of two inorganic precursors with a block copolymer. This solution processed material consists of hexagonally arranged ferromagnetic cobalt ferrite (CFO) nano-cylinders within a matrix of ferroelectric Lead-Zirconium-Titanate (PZT). The initial magnetic permeability of the self-assembled CFO/PZT nanocomposite changes by a factor of 5 through the application of 2.5 V. This work may have significant impact on the

  8. Nanostructured metal foams: synthesis and applications

    SciTech Connect

    Luther, Erik P; Tappan, Bryce; Mueller, Alex; Mihaila, Bogdan; Volz, Heather; Cardenas, Andreas; Papin, Pallas; Veauthier, Jackie; Stan, Marius

    2009-01-01

    Fabrication of monolithic metallic nanoporous materials is difficult using conventional methodology. Here they report a relatively simple method of synthesizing monolithic, ultralow density, nanostructured metal foams utilizing self-propagating combustion synthesis of novel metal complexes containing high nitrogen energetic ligands. Nanostructured metal foams are formed in a post flame-front dynamic assembly with densities as low as 0.011 g/cc and surface areas as high as 270 m{sup 2}/g. They have produced metal foams via this method of titanium, iron, cobalt, nickel, zirconium, copper, palladium, silver, hafnium, platinum and gold. Microstructural features vary as a function of composition and process parameters. Applications for the metal foams are discussed including hydrogen absorption in palladium foams. A model for the sorption kinetics of hydrogen in the foams is presented.

  9. Dynamics of glass-forming liquids. XV. Dynamical features of molecular liquids that form ultra-stable glasses by vapor deposition.

    PubMed

    Chen, Zhen; Richert, Ranko

    2011-09-28

    The dielectric relaxation behavior of ethylbenzene (EBZ) in its viscous regime is measured, and the glass transition temperature (T(g) = 116 K) as well as fragility (m = 98) are determined. While the T(g) of EBZ from this work is consistent with earlier results, the fragility is found much higher than what has been assumed previously. Literature data is supplemented by the present results on EBZ to compile the dynamic behavior of those glass formers that are known to form ultra-stable glasses by vapor deposition. These dynamics are contrasted with those of ethylcyclohexane, a glass former for which a comparable vapor deposition failed to produce an equally stable glassy state. In a graph that linearizes Vogel-Fulcher-Tammann behavior, i.e., the derivative of -logτ with respect to T/T(g) raised to the power of -1/2 versus T/T(g), all ultra-stable glass formers fall onto one master curve in a wide temperature range, while ethylcyclohexane deviates for T ≫ T(g). This result suggests that ultra-stable glass formers share common behavior regarding the dynamics of their supercooled liquid state if scaled to their respective T(g) values, and that fragility and related features are linked to the ability to form ultra-stable materials.

  10. Nanostructured materials

    NASA Astrophysics Data System (ADS)

    Moriarty, Philip

    2001-03-01

    Nanostructured materials may be defined as those materials whose structural elements - clusters, crystallites or molecules - have dimensions in the 1 to 100 nm range. The explosion in both academic and industrial interest in these materials over the past decade arises from the remarkable variations in fundamental electrical, optical and magnetic properties that occur as one progresses from an `infinitely extended' solid to a particle of material consisting of a countable number of atoms. This review details recent advances in the synthesis and investigation of functional nanostructured materials, focusing on the novel size-dependent physics and chemistry that results when electrons are confined within nanoscale semiconductor and metal clusters and colloids. Carbon-based nanomaterials and nanostructures including fullerenes and nanotubes play an increasingly pervasive role in nanoscale science and technology and are thus described in some depth. Current nanodevice fabrication methods and the future prospects for nanostructured materials and nanodevices are discussed.

  11. Nanostructures and mesoscopic systems

    SciTech Connect

    Kirk, W.P. . Dept. of Physics); Reed, M.A. )

    1992-01-01

    This book covers the following topics: nanostructure fabrication; ballistic transport and coherence; low-dimensional tunneling; electron correlation and coulomb blockade; nanostructure arrays and collective effects; theory and modeling of nanostructures; optical properties of nanostructures; and new systems.

  12. Synthesis and characterization of one-dimensional nanostructured fluorine-doped tin dioxide thin films

    NASA Astrophysics Data System (ADS)

    Murakami, Kenji; Bandara, Ajith; Okuya, Masayuki; Shimomura, Masaru; Rajapakse, R. M. G.

    2016-09-01

    This paper describes preparation and characterization of the optically-transparent and electrically conducting thin films of fluoride-doped tin dioxide (FTO) one-dimensional nanostructures and features of the purpose-built, novel and advanced version of spray pyrolysis technique, known as Rotational, Pulsed and Atomized Spray Pyrolysis. This technique allows perfect and simple control of morphology of the nanostructures of FTO layer by adjusting the spray conditions. Effect of the different additives on crystal morphology and texture of the 1-dimensional (1-D) nanostructured FTO thin films is studied. Vertically aligned and well separated nanotubes are easily fabricated using propanone and ethanol as additives. We suggest that propanone additive plays a role to form vertically aligned nanotubes with (101) preferential orientation while (110) face is the predominant plane of well separated nanotubes with ethanol additive. The conductivity of the 1-D nanostructured thin films are also enhanced using the commercial FTO glasses as a substrate.

  13. Enhanced functions of vascular cells on nanostructured Ti for improved stent applications.

    PubMed

    Choudhary, Saba; Haberstroh, Karen M; Webster, Thomas J

    2007-07-01

    Vascular tissue possesses numerous nanostructured surface features, but most metallic vascular stents proposed to restore blood flow are smooth at the nanoscale. Thus, the objective of the present study was to determine in vitro vascular cell functions on nanostructured titanium (Ti) compared to conventional commercially pure (c.p.) Ti. Results of this study showed for the first time greater competitive adhesion of endothelial versus vascular smooth muscle cells on nanostructured Ti compared to conventional Ti after 4 hours. Moreover, when cultured separately, increased endothelial and vascular smooth muscle cell density was observed on nanostructured Ti compared to conventional c.p. Ti after 1, 3, and 5 days; endothelial cells formed confluent monolayers before vascular smooth muscle cells on nanostructured Ti. Results also showed greater total amounts of collagen and elastin synthesis by vascular cells when cultured on nanostructured Ti. Since a major mode of failure of conventional vascular stents is the overgrowth of smooth muscle cells compared to endothelial cells, these results suggest that while the functions of both types of vascular cells were promoted on nanostructured c.p. Ti, endothelial cell functions (of particular importance, cell density or confluence) were enhanced over that of vascular smooth muscle cells. Thus, the present in vitro study showed that vascular stents composed of nanometer c.p. Ti particles may invoke advantageous cellular responses for improved stent applications.

  14. Integration of inorganic nanostructures with polydopamine-derived carbon: tunable morphologies and versatile applications

    NASA Astrophysics Data System (ADS)

    Kong, Junhua; Seyed Shahabadi, Seyed Ismail; Lu, Xuehong

    2016-01-01

    Polydopamine (PDA), a mussel adhesive-inspired biomimetic polymer, has attracted tremendous attention owing to its extremely versatile adhesion properties, facile aqueous coating process, capability of self-assembly to form nanostructures, and abundant surface functional groups for secondary modification. PDA is also a fantastic carbon source because it gives nitrogen (N)-doped graphite-like carbon in high yield, and the carbonized PDA (C-PDA) thin coatings have similar properties to those of N-doped multilayered graphene, i.e., they exhibit high electrical conductivity, and good electrochemical and mechanical properties. In comparison with other carbon sources, an outstanding feature of PDA lies in its ease of integration with inorganic nanostructures and capability for easy tailoring the structure and morphology of the resultant composite nanostructures. In this article, different routes for the preparation of C-PDA-based composite nanostructures, such as carbon/metal oxide and carbon/Si hollow, mesoporous, core-shell, yolk-shell nanostructures, are introduced with typical examples. The structures, morphologies and properties of the C-PDA-based composite nanostructures are also reviewed, and their potential applications in various engineering fields, such as energy storage, solar water splitting, flexible electronics, catalysis, sensing and environmental engineering, are highlighted. Finally a future outlook for this fascinating composite-nanostructure enabler is also presented.

  15. Integration of inorganic nanostructures with polydopamine-derived carbon: tunable morphologies and versatile applications.

    PubMed

    Kong, Junhua; Seyed Shahabadi, Seyed Ismail; Lu, Xuehong

    2016-01-28

    Polydopamine (PDA), a mussel adhesive-inspired biomimetic polymer, has attracted tremendous attention owing to its extremely versatile adhesion properties, facile aqueous coating process, capability of self-assembly to form nanostructures, and abundant surface functional groups for secondary modification. PDA is also a fantastic carbon source because it gives nitrogen (N)-doped graphite-like carbon in high yield, and the carbonized PDA (C-PDA) thin coatings have similar properties to those of N-doped multilayered graphene, i.e., they exhibit high electrical conductivity, and good electrochemical and mechanical properties. In comparison with other carbon sources, an outstanding feature of PDA lies in its ease of integration with inorganic nanostructures and capability for easy tailoring the structure and morphology of the resultant composite nanostructures. In this article, different routes for the preparation of C-PDA-based composite nanostructures, such as carbon/metal oxide and carbon/Si hollow, mesoporous, core-shell, yolk-shell nanostructures, are introduced with typical examples. The structures, morphologies and properties of the C-PDA-based composite nanostructures are also reviewed, and their potential applications in various engineering fields, such as energy storage, solar water splitting, flexible electronics, catalysis, sensing and environmental engineering, are highlighted. Finally a future outlook for this fascinating composite-nanostructure enabler is also presented.

  16. Aqueous Black Colloids of Reticular Nanostructured Gold

    NASA Astrophysics Data System (ADS)

    Stanca, S. E.; Fritzsche, W.; Dellith, J.; Froehlich, F.; Undisz, A.; Deckert, V.; Krafft, C.; Popp, J.

    2015-01-01

    Since ancient times, noble gold has continuously contributed to several aspects of life from medicine to electronics. It perpetually reveals its new features. We report the finding of a unique form of gold, reticular nanostructured gold (RNG), as an aqueous black colloid, for which we present a one-step synthesis. The reticules consist of gold crystals that interconnect to form compact strands. RNG exhibits high conductivity and low reflection, and these features, coupled with the high specific surface area of the material, could prove valuable for applications in electronics and catalysis. Due to high absorption throughout the visible and infrared domain, RNG has the potential to be applied in the construction of sensitive solar cells or as a substrate for Raman spectroscopy.

  17. Aqueous black colloids of reticular nanostructured gold.

    PubMed

    Stanca, S E; Fritzsche, W; Dellith, J; Froehlich, F; Undisz, A; Deckert, V; Krafft, C; Popp, J

    2015-01-20

    Since ancient times, noble gold has continuously contributed to several aspects of life from medicine to electronics. It perpetually reveals its new features. We report the finding of a unique form of gold, reticular nanostructured gold (RNG), as an aqueous black colloid, for which we present a one-step synthesis. The reticules consist of gold crystals that interconnect to form compact strands. RNG exhibits high conductivity and low reflection, and these features, coupled with the high specific surface area of the material, could prove valuable for applications in electronics and catalysis. Due to high absorption throughout the visible and infrared domain, RNG has the potential to be applied in the construction of sensitive solar cells or as a substrate for Raman spectroscopy.

  18. A form of cell death with some features resembling apoptosis in the amitochondrial unicellular organism Trichomonas vaginalis.

    PubMed

    Chose, Olivier; Noël, Christophe; Gerbod, Delphine; Brenner, Catherine; Viscogliosi, Eric; Roseto, Alberto

    2002-05-15

    One of hallmarks of apoptosis is the degradation and concomitant compaction of chromatin. It is assumed that caspases and caspase-independent pathways are rate limiting for the development of nuclear apoptosis. The caspase-independent pathway involves apoptosis-inducing factor (AIF) and leads to DNA fragmentation and peripheral chromatin condensation. Both pathways are the result of activation of death signals that the mitochondrion receives, integrates, and responds to with the release of various molecules (e.g., cytochrome c and AIF). In fact, both pathways have in common the final point of the DNA fragmentation and the mitochondrial origin of molecules that initiate the apoptotic events. Here, we examine the question of whether apoptosis or apoptotic-like processes exist in a unicellular organism that lacks mitochondria. We herein show that a form of cell death with some features resembling apoptosis is indeed present in Trichomonas vaginalis. Characterization of morphological aspects implicated in this event together with the preliminary biochemical data provided may lead to new insight about the evolutionary relationships between the different forms of programmed cell death identified so far.

  19. Chemically enabled nanostructure fabrication

    NASA Astrophysics Data System (ADS)

    Huo, Fengwei

    The first part of the dissertation explored ways of chemically synthesizing new nanoparticles and biologically guided assembly of nanoparticle building blocks. Chapter two focuses on synthesizing three-layer composite magnetic nanoparticles with a gold shell which can be easily functionalized with other biomolecules. The three-layer magnetic nanoparticles, when functionalized with oligonucleotides, exhibit the surface chemistry, optical properties, and cooperative DNA binding properties of gold nanoparticle probes, while maintaining the magnetic properties of the Fe3O4 inner shell. Chapter three describes a new method for synthesizing nanoparticles asymmetrically functionalized with oligonucleotides and the use of these novel building blocks to create satellite structures. This synthetic capability allows one to introduce valency into such structures and then use that valency to direct particle assembly events. The second part of the thesis explored approaches of nanostructure fabrication on substrates. Chapter four focuses on the development of a new scanning probe contact printing method, polymer pen lithography (PPL), which combines the advantages of muCp and DPN to achieve high-throughput, flexible molecular printing. PPL uses a soft elastomeric tip array, rather than tips mounted on individual cantilevers, to deliver inks to a surface in a "direct write" manner. Arrays with as many as ˜11 million pyramid-shaped pens can be brought into contact with substrates and readily leveled optically in order to insure uniform pattern development. Chapter five describes gel pen lithography, which uses a gel to fabricate pen array. Gel pen lithography is a low-cost, high-throughput nanolithography method especially useful for biomaterials patterning and aqueous solution patterning which makes it a supplement to DPN and PPL. Chapter 6 shows a novel form of optical nanolithography, Beam Pen Lithography (BPL), which uses an array of NSOM pens to do nanoscale optical

  20. Prediction of protein subcellular localization by incorporating multiobjective PSO-based feature subset selection into the general form of Chou's PseAAC.

    PubMed

    Mandal, Monalisa; Mukhopadhyay, Anirban; Maulik, Ujjwal

    2015-04-01

    In this article, the possible subcellular location of a protein is predicted using multiobjective particle swarm optimization-based feature selection technique. In general form of pseudo-amino acid composition, the protein sequences are used for constructing protein features. Here, the different amino acids compositions are used to construct the feature sets. Therefore, the data are presented as sample of protein versus amino acid compositions as features. The proposed algorithm tries to maximize the feature relevance and minimize the feature redundancy simultaneously. After proposed algorithm is executed on the multiclass dataset, some features are selected. On this resultant feature subset, tenfold cross-validation is applied and corresponding accuracy, F score, entropy, representation entropy and average correlation are calculated. The performance of the proposed method is compared with that of its single objective versions, sequential forward search, sequential backward search, minimum redundancy maximum relevance with two schemes, CFS, CBFS, [Formula: see text], Fisher discriminant and a Cluster-based technique.

  1. Computational Studies of Nanostructures of Boron

    NASA Astrophysics Data System (ADS)

    Tandy, P.; Yu, M.; Leahy, C.; Tian, W. Q.; Wu, S. Y.; Jayanthi, C. S.

    2009-03-01

    The goal of this work is to develop a reliable semi-empirical Hamiltonian for boron that may be used to predict nanostructures of boron. It is well known that bonding in boron is complicated as it may form three-center, two-electron bonds. The semi-empirical Hamiltonian used here was recently developed by Leahy et al. in the framework of linear combination of atomic orbitals[1]. The salient feature of this Hamiltonian is that it treats environment dependency and charge redistributions on equal footing. It will be shown that such a parameterized Hamiltonian can predict the B80 cage structure with C1 symmetry as found in a recent first-principles study [2]. Having validated our semi-empirical Hamiltonian for boron with small boron clusters and the B80 cage, we have performed a systematic study of other boron nanostructures: (i) larger cage structures (e.g., B215), (ii) boron clusters cut from the bulk alpha boron, and (iii) boron sheets (triangular sheets with and without holes). We will discuss the ground state structures of these boron nanostructures as well as the energetics and HOMO-LUMO gaps of different families of boron clusters as a function their diameters. 1. C. Leahy et al. Phys. Rev. B74, 155408 (2006). 2. N. G. Szwacki et al. PRL 100, 159901 (2008).

  2. Plasmonic Nanostructured Cellular Automata

    NASA Astrophysics Data System (ADS)

    Alkhazraji, Emad; Ghalib, A.; Manzoor, K.; Alsunaidi, M. A.

    2017-03-01

    In this work, we have investigated the scattering plasmonic resonance characteristics of silver nanospheres with a geometrical distribution that is modelled by Cellular Automata using time-domain numerical analysis. Cellular Automata are discrete mathematical structures that model different natural phenomena. Two binary one-dimensional Cellular Automata rules are considered to model the nanostructure, namely rule 30 and rule 33. The analysis produces three-dimensional scattering profiles of the entire plasmonic nanostructure. For the Cellular Automaton rule 33, the introduction of more Cellular Automata generations resulted only in slight red and blue shifts in the plasmonic modes with respect to the first generation. On the other hand, while rule 30 introduced significant red shifts in the resonance peaks at early generations, at later generations however, a peculiar effect is witnessed in the scattering profile as new peaks emerge as a feature of the overall Cellular Automata structure rather than the sum of the smaller parts that compose it. We strongly believe that these features that emerge as a result adopting the different 256 Cellular Automata rules as configuration models of nanostructures in different applications and systems might possess a great potential in enhancing their capability, sensitivity, efficiency, and power utilization.

  3. Specific features of the atomic structure of metallic layers of multilayered (CoFeZr/SiO2)32 and (CoFeZr/ a-Si)40 nanostructures with different interlayers

    NASA Astrophysics Data System (ADS)

    Domashevskaya, E. P.; Guda, A. A.; Chernyshev, A. V.; Sitnikov, V. G.

    2017-02-01

    Multilayered nanostructures (MN) were prepared by ion-beam successive sputtering from two targets, one of which was a metallic Co45Fe45Zr10 alloy plate and another target was a quartz (SiO2) or silicon plate on the surface of a rotating glass-ceramic substrate in an argon atmosphere. The Co and Fe K edges X-ray absorption fine structure of XANES in the (CoFeZr/SiO2)32 sample with oxide interlayers was similar to XANES of metallic Fe foil. This indicated the existence in metallic layers of multilayered CoFeZr nanocrystals with a local environment similar to the atomic environment in solid solutions on the base of bcc Fe structure, which is also confirmed by XRD data. XANES near the Co and Fe K edges absorption in another multilayered nanostructure with silicon interlayers (CoFeZr/ a-Si)40 differs from XANES of MN with dielectric SiO2 interlayer, which demonstrates a dominant influence of the Fe-Si and Co-Si bonds in the local environment of 3 d Co and Fe metals when they form CoFeSi-type silicide phases in thinner bilayers of this MN.

  4. Photocatalytic activity of nanostructured {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder formed via a polyelectrolyte-multilayer-assisted sol-gel reaction

    SciTech Connect

    Logar, Manca; Kocjan, Andraz; Dakskobler, Ales

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer PEM assisted synthesis for {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder is developed. Black-Right-Pointing-Pointer Nanoparticulate TiO{sub 2} layer results in high specific surface area composite powder. Black-Right-Pointing-Pointer {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder exhibit enhanced photocatalytic activity. -- Abstract: Nanostructured, {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder was fabricated via an in situ, sol-gel reaction of titanium iso-propoxide in a self-assembled, polyelectrolyte multilayer (PEM) formed on the surface of high-specific-area, polycrystalline, {gamma}-Al{sub 2}O{sub 3} lamellas. The infiltration of the titanium precursor into the PEM, followed by the hydrolysis and condensation reactions with the water absorbed in the PEM after annealing, resulted in the formation of a nanostructured TiO{sub 2} layer on the surface of the {gamma}-Al{sub 2}O{sub 3} lamellas. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were employed to evaluate the morphology, the chemical composition and the crystallinity of the {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} particles of the composite powder. The as-formed, nanostructured, {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder exhibited a 2.7-times-higher photo-activity in the near-UV region compared to commercially available TiO{sub 2} (Degusa P25), as monitored by the photo-decomposition of a methylene blue (MB) dye.

  5. Epidemiological and clinical features of the endomyocardial form of restrictive cardiomyopathy in cats: a review of 41 cases.

    PubMed

    Kimura, Yusuke; Fukushima, Ryuji; Hirakawa, Atsushi; Kobayashi, Masayuki; Machida, Noboru

    2016-06-01

    Examination of our necropsy records for the period 2005 to 2014 yielded 41 cases of the endomyocardial form of restrictive cardiomyopathy among 327 cats with evidence of heart disease, and here, we reviewed their epidemiological and clinical features. The medical data obtained retrospectively included signalment, presenting complaints, findings of physical examination, results of various diagnostic tests, methods of treatment and survival times. Except for one Chinchilla Persian cat, all were domestic short-haired cats. The mean age at death was 7.3 ± 4.5 years (median, 6 years; range, 4 months to 19 years), and males accounted for 61% (25/41) of the total. Dyspnea was the most common clinical sign, being evident in 83% (35/41) of the cats. Hind limb paresis or paralysis due to aortic thromboembolism was evident in 41% (17/41). Arrhythmias of atrial origin were common. Echocardiography commonly revealed left atrial or biatrial enlargement with severe endocardial thickening of the left ventricle. Most of the affected cats had a poor outcome; the disease duration ranged from 1 to 977 days, and the median survival period was 30 days.

  6. Epidemiological and clinical features of the endomyocardial form of restrictive cardiomyopathy in cats: a review of 41 cases

    PubMed Central

    KIMURA, Yusuke; FUKUSHIMA, Ryuji; HIRAKAWA, Atsushi; KOBAYASHI, Masayuki; MACHIDA, Noboru

    2016-01-01

    Examination of our necropsy records for the period 2005 to 2014 yielded 41 cases of the endomyocardial form of restrictive cardiomyopathy among 327 cats with evidence of heart disease, and here, we reviewed their epidemiological and clinical features. The medical data obtained retrospectively included signalment, presenting complaints, findings of physical examination, results of various diagnostic tests, methods of treatment and survival times. Except for one Chinchilla Persian cat, all were domestic short-haired cats. The mean age at death was 7.3 ± 4.5 years (median, 6 years; range, 4 months to 19 years), and males accounted for 61% (25/41) of the total. Dyspnea was the most common clinical sign, being evident in 83% (35/41) of the cats. Hind limb paresis or paralysis due to aortic thromboembolism was evident in 41% (17/41). Arrhythmias of atrial origin were common. Echocardiography commonly revealed left atrial or biatrial enlargement with severe endocardial thickening of the left ventricle. Most of the affected cats had a poor outcome; the disease duration ranged from 1 to 977 days, and the median survival period was 30 days. PMID:26822001

  7. Sintering and ripening resistant noble metal nanostructures

    DOEpatents

    van Swol, Frank B; Song, Yujiang; Shelnutt, John A; Miller, James E; Challa, Sivakumar R

    2013-09-24

    Durable porous metal nanostructures comprising thin metal nanosheets that are metastable under some conditions that commonly produce rapid reduction in surface area due to sintering and/or Ostwald ripening. The invention further comprises the method for making such durable porous metal nanostructures. Durable, high-surface area nanostructures result from the formation of persistent durable holes or pores in metal nanosheets formed from dendritic nanosheets.

  8. Nanostructure Neutron Converter Layer Development

    NASA Technical Reports Server (NTRS)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  9. Planar plasmonic chiral nanostructures

    NASA Astrophysics Data System (ADS)

    Zu, Shuai; Bao, Yanjun; Fang, Zheyu

    2016-02-01

    A strong chiral optical response induced at a plasmonic Fano resonance in a planar Au heptamer nanostructure was experimentally and theoretically demonstrated. The scattering spectra show the characteristic narrow-band feature of Fano resonances for both left and right circular polarized lights, with a chiral response reaching 30% at the Fano resonance. Specifically, we systematically investigate the chiral response of planar heptamers with gradually changing the inter-particle rotation angles and separation distance. The chiral spectral characteristics clearly depend on the strength of Fano resonances and the associated near-field optical distributions. Finite element method simulations together with a multipole expansion method demonstrate that the enhanced chirality is caused by the excitation of magnetic quadrupolar and electric toroidal dipolar modes. Our work provides an effective method for the design of 2D nanostructures with a strong chiral response.A strong chiral optical response induced at a plasmonic Fano resonance in a planar Au heptamer nanostructure was experimentally and theoretically demonstrated. The scattering spectra show the characteristic narrow-band feature of Fano resonances for both left and right circular polarized lights, with a chiral response reaching 30% at the Fano resonance. Specifically, we systematically investigate the chiral response of planar heptamers with gradually changing the inter-particle rotation angles and separation distance. The chiral spectral characteristics clearly depend on the strength of Fano resonances and the associated near-field optical distributions. Finite element method simulations together with a multipole expansion method demonstrate that the enhanced chirality is caused by the excitation of magnetic quadrupolar and electric toroidal dipolar modes. Our work provides an effective method for the design of 2D nanostructures with a strong chiral response. Electronic supplementary information (ESI) available

  10. Peptide nanostructures in biomedical technology.

    PubMed

    Feyzizarnagh, Hamid; Yoon, Do-Young; Goltz, Mark; Kim, Dong-Shik

    2016-09-01

    Nanostructures of peptides have been investigated for biomedical applications due to their unique mechanical and electrical properties in addition to their excellent biocompatibility. Peptides may form fibrils, spheres and tubes in nanoscale depending on the formation conditions. These peptide nanostructures can be used in electrical, medical, dental, and environmental applications. Applications of these nanostructures include, but are not limited to, electronic devices, biosensing, medical imaging and diagnosis, drug delivery, tissue engineering and stem cell research. This review offers a discussion of basic synthesis methods, properties and application of these nanomaterials. The review concludes with recommendations and future directions for peptide nanostructures. WIREs Nanomed Nanobiotechnol 2016, 8:730-743. doi: 10.1002/wnan.1393 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

  11. Microscopic characterization of peptide nanostructures.

    PubMed

    Mammadov, Rashad; Tekinay, Ayse B; Dana, Aykutlu; Guler, Mustafa O

    2012-02-01

    Peptide-based nanomaterials have been utilized for various applications from regenerative medicine to electronics since they provide several advantages including easy synthesis methods, numerous routes for functionalization and biomimicry of secondary structures of proteins which leads to design of self-assembling peptide molecules to form nanostructures. Microscopic characterization at nanoscale is critical to understand processes directing peptide molecules to self-assemble and identify structure-function relationship of the nanostructures. Here, fundamental studies in microscopic characterization of peptide nanostructures are discussed to provide insights in widely used microscopy tools. In this review, we will encompass characterization studies of peptide nanostructures with modern microscopes, such as TEM, SEM, AFM, and advanced optical microscopy techniques. We will also mention specimen preparation methods and describe interpretation of the images.

  12. Larval myogenesis in Echinodermata: conserved features and morphological diversity between class-specific larval forms of Echinoidae, Asteroidea, and Holothuroidea.

    PubMed

    Dyachuk, Vyacheslav; Odintsova, Nelly

    2013-01-01

    The myogenesis of class-specific larval forms of three classes belonging to the phylum Echinodermata (Echinoidae, Asteroidea, and Holothuroidea) was investigated via gross-anatomy and comparative morphology of larval muscles. Using staining with phalloidin and antibodies against the muscle proteins, with subsequent CLSM and 3D imaging, we have examined myogenesis in the larvae from the gastrula stage to pre-metamorphosis larval stages. We have shown that temporal and spatial expression of muscle proteins is similar in echinoidea and asteroidea larvae but differs in holothuroidea larvae at early developmental stages. New insights regarding the protein composition of maturing muscular fibrils during development in echinoderm larvae were detected. The first differentiating muscle structures in all tested classes have been found to be circular esophageal muscles that are associated with larval feeding. During early differentiation of echinoderm larval muscle cells, we observed that the expression patterns of the muscle proteins were not uniform but with a characteristic diffuse distribution, which is typical for smooth muscle. An unusual pattern of expression of the muscle proteins was detected in larval sphincters: the thick muscle proteins were first expressed during the early developmental stages, whereas F-actin appeared at later stages. In addition, paired star-shaped muscles were revealed in the mature Echinoidae plutei, but were absent in the Asteroidea, and Holothuroidea larvae. All tested species of Echinodermata exhibited both conserved features of muscle morphology during development indicating a common life history strategy and a planktonic habitat, and also an extensive morphological diversity representing specific anatomical adaptations during development.

  13. Anchored nanostructure materials and method of fabrication

    DOEpatents

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2012-11-27

    Anchored nanostructure materials and methods for their fabrication are described. The anchored nanostructure materials may utilize nano-catalysts that include powder-based or solid-based support materials. The support material may comprise metal, such as NiAl, ceramic, a cermet, or silicon or other metalloid. Typically, nanoparticles are disposed adjacent a surface of the support material. Nanostructures may be formed as anchored to nanoparticles that are adjacent the surface of the support material by heating the nano-catalysts and then exposing the nano-catalysts to an organic vapor. The nanostructures are typically single wall or multi-wall carbon nanotubes.

  14. Antibacterial Au nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-01-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It

  15. Organizational-Pedagogical Conditions to Form the Foreign Competence in Students with the Features of Linguistic Giftedness

    ERIC Educational Resources Information Center

    Panfilova, Valentina Michailovna; Panfilov, Alexey Nikolaevich; Merzon, Elena Efimovna

    2015-01-01

    The study of foreign competence at the present stage of the higher education development becomes more relevant. The article emphasizes the organizational-pedagogical conditions, providing the formation of foreign competence in students with the features of linguistic giftedness. The way to reveal the students, who have the features of linguistic…

  16. Portraits of colloidal hybrid nanostructures: controlled synthesis and potential applications.

    PubMed

    Nguyen, Thanh-Dinh

    2013-03-01

    Inorganic hybrid nanostructures containing two or more nanocomponents have been emerging in many areas of materials science in recent years. The particle-particle interactions in a hybrid particle system could significantly improve existing local electronic structure and induce tunable physiochemical responses. The current work reviews the diverse inorganic hybrid nanostructures formed by adhesion of the different single components via seed-mediated method. The hybrid nanomaterials have great potentials for real applications in many other fields. The nanohybrids have been used as efficient heterocatalysts for carbon monoxide conversion and photodegradation of organic contaminants. The enhanced catalytic activity of these hybrid nanocatalysts could be attributed the formation of oxygen vacancies and electron transfer across the structural junction in a hybrid system as a result of the interfacial particle-particle interactions. The synergistic combination of up-converting and semiconducting properties in an up-converting semiconducting hybrid particle results in appearance of sub-band-gap photoconductivity. This behavior has a great significance for the design of photovoltaic devices for effective solar energy conversion. The functionalization and subsequent bioconjugation of the hybrid nanostructures to afford the multifunctional nanomedical platforms for simultaneous diagnosis and therapy are reviewed. The conjugated multifunctional hybrid nanostructures exhibit high biocompatibility and highly selective binding with functional groups-fabricated alive organs through delivering them to the tumor sites. The clever combinations of multifunctional features and antibody conjugation within these vehicles make them to generally offer new opportunities for clinical diagnostics and therapeutics.

  17. Directed spatial organization of zinc oxide nanostructures

    DOEpatents

    Hsu, Julia; Liu, Jun

    2009-02-17

    A method for controllably forming zinc oxide nanostructures on a surface via an organic template, which is formed using a stamp prepared from pre-defined relief structures, inking the stamp with a solution comprising self-assembled monolayer (SAM) molecules, contacting the stamp to the surface, such as Ag sputtered on Si, and immersing the surface with the patterned SAM molecules with a zinc-containing solution with pH control to form zinc oxide nanostructures on the bare Ag surface.

  18. Lightweight Beryllium Free Nanostructured Nanostructured Composites

    DTIC Science & Technology

    2007-11-02

    Plasma Processes, Inc. Lightweight Beryllium Free Nanostructured Composites SBIR Contract DASG60-02-P-41 Phase I Final Report 1/15/03 Submitted by...Report Type N/A Dates Covered (from... to) - Title and Subtitle Lightweight Beryllium Free Nanostructured Nanostructured Composites Contract

  19. [The specific features of relations of the fleas Xenopsylla cheopis L. to the plague microbe of the Altai subspecies, its L-forms and revertant].

    PubMed

    Bazanova, L P; Inokent'eva, T I; Maevskiĭ, M P

    2011-01-01

    The rate and changes in the formation of bacterial lumps and blocks of the proventriculus in Xenopsylla cheopis fleas in their contamination with the plague microbe of the Altai subspecies, its L-form and revertant were studied to clarify the specific features of relations with the vector, including its transmission ability. The plague microbe of the Altai subspecies, which was exposed to L-transformation in the resistant organism of a warm-blooded host (a guinea pig), as well as L-form revertants obtained on nutrient media substantially lost their ability to get acclimatized in the vector and to form a proventricular block. The capacity to form lumps did not greatly differ in L- and original form of the microbe. At the same time, the ratio of the formed blocks and lumps was much lower, which points to the instability of the formed masses. This is supported by the detection of specimens with partial blocks only among the fleas infected with L-forms. The reversed bacterial form was exceeded in the rate of formation of lumps by the original and L-forms. This may be associated with the reversion of L-forms on the nutrient medium rather than in the vector. At the same time, the revertant formed stable blocks in shorter periods than did L-forms and caused a generalization of the infection in plague-infected mice, which may be important for further transmission of the microbe.

  20. Study of the Structure, Composition, and Stability of Yttrium-Ti-Oxygen nm-Scale Features in Nano-Structured Ferritic Alloys

    NASA Astrophysics Data System (ADS)

    Cunningham, Nicholas John

    This work advances the understanding of the Y-Ti-O nanofeatures (NFs) in nanostructured ferritic alloys (NFAs); a class of high temperature, oxide dispersion strengthened iron alloys with applications in both advanced fission and fusion reactors. NFAs exhibit high creep strength up to 800ºC and a remarkable radiation damage tolerance and He management. However, the NFs, which are responsible for these properties, are not fully understood. This work addresses key questions including: a) what is the NF structure and composition and how are they affected by alloy composition and processing; b) what is the NFA long-term thermal stability; c) and what alternative processing paths are available to reduce costs and produce more uniform NF distributions? A detailed study using small angle neutron scattering (SANS), transmission electron microscopy (TEM-group member Y. Wu), and atom probe tomography (APT) evaluated the NF average size (), number density (N), volume fraction (f), composition, and structure in two heats of the commercial NFA MA957. The and N were ≈2.6 nm and ≈5x1023 m-3 , respectively, for both heats, with TEM indicating the NF are Y 2Ti2O7. However, SANS indicates a mixture of NF compositions or atomic densities with a difference between the heats, while APT shows compositions with ≈ 10% Cr and a Y/Ti ratio < 1. However, microscope artifacts such as preferential undercounting of Y and O or trajectory aberrations that prevent resolving Ti segregation to the NF-matrix interface could account for the discrepancy. The microstructure and NFs in MA957 were stable for long times at temperatures up to 900ºC. Notably, Ti in the matrix and some from the NFs migrates to large, Ti-rich phases. Aging at higher temperatures up to 1000ºC for 19.5 kh produced modest coarsening for ≈ 3.8 nm and ≈30% increase in grain size for a corresponding 13% reduction in microhardness. A coarsening model shows no significant NF coarsening will occur at temperatures less than

  1. TOPICAL REVIEW: Hybrid nanostructures for efficient light harvesting

    NASA Astrophysics Data System (ADS)

    Mackowski, Sebastian

    2010-05-01

    Hybrid nanostructures are systems composed of two or more nanostructures designed for improving the performance over individual components. In this work we introduce the concept of bridging natural photosynthetic protein-pigment complexes with nanostructures fabricated in an artificial way, such as semiconductor nanocrystals, metallic nanoparticles or carbon nanotubes, with the purpose of enhancing the efficiency of light harvesting either via plasmon excitation in metals or absorption tunability characteristics of semiconductors. In addition to presenting basic features of inorganic nanostructures, we discuss recent advances in the field of hybrid nanostructures composed of photosynthetic pigment-protein complexes.

  2. One-dimensional semiconductor nanostructure based thin-film partial composite formed by transfer implantation for high-performance flexible and printable electronics at low temperature.

    PubMed

    Moon, Kyeong-Ju; Lee, Tae-Il; Choi, Ji-Hyuk; Jeon, Joohee; Kang, Youn Hee; Kar, Jyoti Prakash; Kang, Jung Han; Yun, Ilgu; Myoung, Jae-Min

    2011-01-25

    Having high bending stability and effective gate coupling, the one-dimensional semiconductor nanostructures (ODSNs)-based thin-film partial composite was demonstrated, and its feasibility was confirmed through fabricating the Si NW thin-film partial composite on the poly(4-vinylphenol) (PVP) layer, obtaining uniform and high-performance flexible field-effect transistors (FETs). With the thin-film partial composite optimized by controlling the key steps consisting of the two-dimensional random dispersion on the hydrophilic substrate of ODSNs and the pressure-induced transfer implantation of them into the uncured thin dielectric polymer layer, the multinanowire (NW) FET devices were simply fabricated. As the NW density increases, the on-current of NW FETs increases linearly, implying that uniform NW distribution can be obtained with random directions over the entire region of the substrate despite the simplicity of the drop-casting method. The implantation of NWs by mechanical transfer printing onto the PVP layer enhanced the gate coupling and bending stability. As a result, the enhancements of the field-effect mobility and subthreshold swing and the stable device operation up to a 2.5 mm radius bending situation were achieved without an additional top passivation.

  3. Leveraging Fourth and Sixth Graders' Experiences to Reveal Understanding of the Forms and Features of Distributed Causality

    ERIC Educational Resources Information Center

    Grotzer, Tina A.; Derbiszewska, Katarzyna; Solis, S. Lynneth

    2017-01-01

    Research has focused on students' difficulties understanding phenomena in which agency is distributed across actors whose individual-level behaviors converge to result in collective outcomes. Building on Levy and Wilensky (2008), this study identified features of distributed causality students understand and that may offer affordances for…

  4. Leveraging Fourth and Sixth Graders' Experiences to Reveal Understanding of the Forms and Features of Distributed Causality

    ERIC Educational Resources Information Center

    Grotzer, Tina A.; Derbiszewska, Katarzyna; Solis, S. Lynneth

    2017-01-01

    Research has focused on students' difficulties understanding phenomena in which agency is distributed across actors whose individual-level behaviors converge to result in collective outcomes. Building on Levy and Wilensky (2008), this study identified features of distributed causality students understand and that may offer affordances for…

  5. DNA nanostructure meets nanofabrication.

    PubMed

    Zhang, Guomei; Surwade, Sumedh P; Zhou, Feng; Liu, Haitao

    2013-04-07

    Recent advances in DNA nanotechnology have made it possible to construct DNA nanostructures of almost arbitrary shapes with 2-3 nm of precision in their dimensions. These DNA nanostructures are ideal templates for bottom-up nanofabrication. This review highlights the challenges and recent advances in three areas that are directly related to DNA-based nanofabrication: (1) fabrication of large scale DNA nanostructures; (2) pattern transfer from DNA nanostructure to an inorganic substrate; and (3) directed assembly of DNA nanostructures.

  6. Formation of nanostructures at the glass-carbon surface exposed to laser radiation

    SciTech Connect

    Abramov, D V; Gerke, M N; Kucherik, A O; Kutrovskaya, S V; Prokoshev, V G; Arakelyan, S M

    2007-11-30

    An experimental technique for obtaining nanostructures in the field of high-power laser radiation at the surface of carbon materials is developed. A specific feature of this technique is the formation of liquid carbon inside the region of laser action in the sample exposed to radiation in air at a pressure of {approx}1 atm. Several types of nanostructures (quasi-domains and nanopeaks) are detected in the laser cavern and beyond the range of laser action. Mechanisms of formation of such structures are proposed. The formation of quasi-domains is related to crystallisation of the melt. The nanopeak groups are formed outside the laser action region during the deposition of hot vapours of the material escaping from this region. The dependences of the variation in morphological properties of the nanostructures on the duration of laser action and the radii of typical cavern zones on the laser radiation power are obtained. (interaction of laser radiation with matter. laser plasma)

  7. Optimized design of a nanostructured SPCE-based multipurpose biosensing platform formed by ferrocene-tethered electrochemically-deposited cauliflower-shaped gold nanoparticles

    PubMed Central

    Argoubi, Wicem; Saadaoui, Maroua

    2015-01-01

    Summary The demand for on-site nanodevices is constantly increasing. The technology development for the design of such devices is highly regarded. In this work, we report the design of a disposable platform that is structured with cauliflower-shaped gold nanoparticles (cfAuNPs) and we show its applications in immunosensing and enzyme-based detection. The electrochemical reduction of Au(III) allows for the electrodeposition of highly dispersed cauliflower-shaped gold nanoparticles on the surface of screen-printed carbon electrodes (SPCEs). The nanostructures were functionalized using ferrocenylmethyl lipoic acid ester which allowed for the tethering of the ferrocene group to gold, which serves as an electrochemical transducer/mediator. The bioconjugation of the surface with anti-human IgG antibody (α-hIgG) or horseradish peroxidase (HRP) enzyme yields biosensors, which have been applied for the selective electrochemical detection of human IgG (hIgG) or H2O2 as model analytes, respectively. Parameters such as the number of sweeps, amount of charge generated from the oxidation of the electrodeposited gold, time of incubation and concentration of the ferrocene derivatives have been studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Selectivity and specificity tests have been also performed in the presence of potentially interfering substances to either hIgG or H2O2. Results showed that the devised immunosensor is endowed with good selectivity and specificity in the presence of several folds of competitive analytes. The enzyme-based platform showed a good catalytic activity towards H2O2 oxidation which predestined it to potential applications pertaining to enzymatic kinetics studies. The levels of hIgG in human serum and H2O2 in honey were successfully determined and served as assessment tools of the applicability of the platforms for real samples analysis. PMID:26425435

  8. Ceramic nanostructures and methods of fabrication

    DOEpatents

    Ripley, Edward B.; Seals, Roland D.; Morrell, Jonathan S.

    2009-11-24

    Structures and methods for the fabrication of ceramic nanostructures. Structures include metal particles, preferably comprising copper, disposed on a ceramic substrate. The structures are heated, preferably in the presence of microwaves, to a temperature that softens the metal particles and preferably forms a pool of molten ceramic under the softened metal particle. A nano-generator is created wherein ceramic material diffuses through the molten particle and forms ceramic nanostructures on a polar site of the metal particle. The nanostructures may comprise silica, alumina, titania, or compounds or mixtures thereof.

  9. A transparent nanostructured optical biosensor.

    PubMed

    He, Yuan; Li, Xiang; Que, Long

    2014-05-01

    Herein we report a new transparent nanostructured Fabry-Perot interferometer (FPI) device. The unique features of the nanostructured optical device can be summarized as the following: (i) optically transparent nanostructured optical device; (ii) simple and inexpensive for fabrication; (iii) easy to be fabricated and scaled up as an arrayed format. These features overcome the existing barriers for the current nanopore-based interferometric optical biosensors by measuring the transmitted optical signals rather than the reflected optical signals, thereby facilitating the optical testing significantly for the arrayed biosensors and thus paving the way for their potential for high throughput biodetection applications. The optically transparent nanostructures (i.e., anodic aluminum oxide nanopores) inside the FPI devices are fabricated from 2.2 microm thick lithographically patterned Al thin film on an indium tin oxide (ITO) glass substrate using a two-step anodization process. Utilizing the binding between Protein A and porcine immunoglobulin G (IgG) as a model, the detection of the bioreaction between biomolecules has been demonstrated successfully. Experiments found that the lowest detection concentration of proteins is in the range of picomolar level using current devices, which can be easily tuned into the range of femtomolar level by optimizing the performance of devices.

  10. Titanate and titania nanostructures and nanostructure assemblies, and methods of making same

    DOEpatents

    Wong, Stanislaus S; Mao, Yuanbing

    2013-05-14

    The invention relates to nanomaterials and assemblies including, a micrometer-scale spherical aggregate comprising: a plurality of one-dimensional nanostructures comprising titanium and oxygen, wherein the one-dimensional nanostructures radiate from a hollow central core thereby forming a spherical aggregate.

  11. Titanate and titania nanostructures and nanostructure assemblies, and methods of making same

    SciTech Connect

    Wong, Stanislaus S.; Mao, Yuanbing

    2016-06-14

    The invention relates to nanomaterial's and assemblies including, a micrometer-scale spherical aggregate comprising: a plurality of one-dimensional nanostructures comprising titanium and oxygen, wherein the one-dimensional nanostructures radiate from a hollow central core thereby forming a spherical aggregate.

  12. Structural Features of Apicomplexan Pore-Forming Proteins and Their Roles in Parasite Cell Traversal and Egress.

    PubMed

    Guerra, Alfredo J; Carruthers, Vern B

    2017-08-29

    Apicomplexan parasites cause diseases, including malaria and toxoplasmosis, in a range of hosts, including humans. These intracellular parasites utilize pore-forming proteins that disrupt host cell membranes to either traverse host cells while migrating through tissues or egress from the parasite-containing vacuole after replication. This review highlights recent insight gained from the newly available three-dimensional structures of several known or putative apicomplexan pore-forming proteins that contribute to cell traversal or egress. These new structural advances suggest that parasite pore-forming proteins use distinct mechanisms to disrupt host cell membranes at multiple steps in parasite life cycles. How proteolytic processing, secretion, environment, and the accessibility of lipid receptors regulate the membranolytic activities of such proteins is also discussed.

  13. Performance comparison of the Prophecy (forecasting) Algorithm in FFT form for unseen feature and time-series prediction

    NASA Astrophysics Data System (ADS)

    Jaenisch, Holger; Handley, James

    2013-06-01

    We introduce a generalized numerical prediction and forecasting algorithm. We have previously published it for malware byte sequence feature prediction and generalized distribution modeling for disparate test article analysis. We show how non-trivial non-periodic extrapolation of a numerical sequence (forecast and backcast) from the starting data is possible. Our ancestor-progeny prediction can yield new options for evolutionary programming. Our equations enable analytical integrals and derivatives to any order. Interpolation is controllable from smooth continuous to fractal structure estimation. We show how our generalized trigonometric polynomial can be derived using a Fourier transform.

  14. Structural features of the pore formed by Staphylococcus aureus alpha-toxin inferred from chemical modification and primary structure analysis.

    PubMed

    Menestrina, G; Belmonte, G; Parisi, V; Morante, S

    1992-09-01

    Staphylococcus aureus alpha-toxin makes cells and model membranes permeable to ions and uncharged molecules by opening oligomeric pores of uniform size. Its primary sequence reveals peculiar features which give some hints on the structure of the pore. A flexible region separating the toxin into two halves, several amphiphilic beta-strands and two amphiphilic alpha-helices long enough to span the hydrophobic core of the lipid bilayer are predicted. In analogy to bacterial porins, we propose that the inner walls of the pore are, at least in part, built by an amphiphilic beta-barrel. The model is consistent with circular dichroism data and with the electrophysiological properties of the pore. Functional information on this toxin were obtained by chemical modification of its four histidine residues. Specific carbethoxylation suggested they have different roles: one is required for specific receptor binding, one for oligomerisation and two for unspecific lipid binding. A tentative assignment of each histidine to its specific role is done on the basis of the structural predictions. A functionally related hemolysin, Aeromonas hydrophyla aerolysin, reveals remarkably similar features including the presence and location of histidines involved in receptor binding and oligomerisation.

  15. Decreased bacteria density on nanostructured polyurethane.

    PubMed

    Yao, Chang; Webster, Thomas J; Hedrick, Matthew

    2014-06-01

    As is well known, medical device infections are a growing clinical problem with no clear solution due to previous failed attempts of using antibiotics to decrease bacteria functions for which bacteria quickly develop a resistance toward. Because of their altered surface energetics, the objective of the present in vitro study was to create nanoscale surface features on polyurethane (PU) by soaking PU films in HNO3 and to determine bacteria (specifically, S. epidermidis, E. coli, and P. mirabilis) colony forming units after 1 h. Such bacteria frequently infect numerous medical devices. Results provided the first evidence that without using antibiotics, S. epidermidis density decreased by 5 and 13 times, E. coli density decreased by 6 and 20 times, and P. mirabilis density decreased by 8 and 35 times compared to conventional PU and a tissue engineering control small intestine submucosa (SIS), respectively. Material characterization studies revealed significantly greater nanoscale roughness and hydrophobicity for the HNO3-treated nanostructured PU compared to conventional PU (albeit, still hydrophilic) which may provide a rationale for the observed decreased bacteria responses. In addition, significantly greater amounts of fibronectin adsorption from serum were measured on nanorough compared conventional PU which may explain the decreased bacteria growth. In summary, this study provides significant promise for the use of nanostructured PU to decrease bacteria functions without the use of antibiotics, clearly addressing the wide spread problem of increased medical device infections observed today.

  16. [Features of biochemical changes in blood serum according to the form of progression of idiopathic and dysplastic coxarthrosis].

    PubMed

    Gaĭko, G V; Magomedov, A M; Kalashnikov, A V; Kuzub, T A; Polishchuk, L V

    2013-01-01

    Carried out biochemical studies of blood serum (collagenase activity, glycosamineglicans and hydroxyproline fractions) of 72 patients with hip idiopathic osteoarthrosis and 30 patients with dysplastic osteoarthrosis of the iv-th stage in.accordance with J. H. Kellgren and J. S. Lavrence depending on the form of pathologic process progression. It has been proved that both with idiopathic and dysplastic coxartrosis metabolism of basic protein of osteochonrous tissue was broken both in catabolic and in synthetic phase of this process. The most deep changes 1 of biochemical values (collagenase, free and proteinbinded hydroxyprolines, the content of glycosamines) have been observed with rapid form of course progression of idiopathic and dysplastic coxarthrosis. Definite appropriateness promotesin.patients better understanding of coxarthrosis pathogenese, development of diagnostic and medical measures for patients with this severe orthopedic pathology.

  17. Formation of nanostructure and nano-hardness characterization on the meso-scale workpiece by a novel laser indirect shock forming method.

    PubMed

    Hu, Y; Liu, H X; Wang, X; Shen, Z B; Li, P; Gu, C X; Gu, Y X; Lu, M M; Zhang, Q

    2013-04-01

    The meso-scale workpiece with greatly enhanced mechanical properties is potential to be widely used in the electronics productions and micro-electro mechanical systems. In this study, it demonstrates that the meso-scale cup-shape workpiece with good geometry can be obtained by a novel laser indirect shock forming method. After the forming process, the mechanical properties and microstructures of the formed workpiece were characterized. By transmission electron microscope observation, it was found that a mixed refined microstructure consisting of nano-scale twins embedded in nano-sized grains was produced at the center of the formed sample. Formation of these nanograins could be mainly attributed to two mechanisms: twin-twin intersections and twin∕matrix lamellae fragmentation. By nanoindentation tests, it reveals that the hardness of the sample has increased greatly after laser shock forming and the hardness increases with the laser energy. The elevated hardness originates from a considerable number of nano-scale twins and nanograins, which possess a pretty high strength due to the significant effects of grain boundary strengthening and twin boundary strengthening.

  18. Synthesis, morphology, optical and photocatalytic performance of nanostructured β-Ga{sub 2}O{sub 3}

    SciTech Connect

    Girija, K.; Thirumalairajan, S.; Avadhani, G.S.; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2013-06-01

    Highlights: ► Nanostructures of β-Ga{sub 2}O{sub 3} were prepared using facile reflux condensation process. ► The pH of the reaction mixture shows evident influence on the size and shape of the nanostructures formed. ► The nanostructures exhibited good photocatalytic activity toward Rhodamine B and was found to be superior for higher pH value. - Abstract: Fine powders of β-Ga{sub 2}O{sub 3} nanostructures were prepared via low temperature reflux condensation method by varying the pH value without using any surfactant. The pH value of reaction mixture had great influence on the morphology of final products. High crystalline single phase β-Ga{sub 2}O{sub 3} nanostructures were obtained by thermal treatment at 900 °C which was confirmed by X-ray diffraction and Raman spectroscopy. The morphological analysis revealed rod like nanostructures at lower and higher pH values of 6 and 10, while spindle like structures were obtained at pH = 8. The phase purity and presence of vibrational bands were identified using Fourier transform infrared spectroscopy. The optical absorbance spectrum showed intense absorption features in the UV spectral region. A broad blue emission peak centered at 441 nm due to donor–acceptor gallium–oxygen vacancy pair recombination appeared. The photocatalytic activity toward Rhodamine B under visible light irradiation was higher for nanorods at pH 10.

  19. Nanostructured magnesium has fewer detrimental effects on osteoblast function

    PubMed Central

    Weng, Lucy; Webster, Thomas J

    2013-01-01

    Efforts have been made recently to implement nanoscale surface features on magnesium, a biodegradable metal, to increase bone formation. Compared with normal magnesium, nanostructured magnesium has unique characteristics, including increased grain boundary properties, surface to volume ratio, surface roughness, and surface energy, which may influence the initial adsorption of proteins known to promote the function of osteoblasts (bone-forming cells). Previous studies have shown that one way to increase nanosurface roughness on magnesium is to soak the metal in NaOH. However, it has not been determined if degradation of magnesium is altered by creating nanoscale features on its surface to influence osteoblast density. The aim of the present in vitro study was to determine the influence of degradation of nanostructured magnesium, created by soaking in NaOH, on osteoblast density. Our results showed a less detrimental effect of magnesium degradation on osteoblast density when magnesium was treated with NaOH to create nanoscale surface features. The detrimental degradation products of magnesium are of significant concern when considering use of magnesium as an orthopedic implant material, and this study identified a surface treatment, ie, soaking in NaOH to create nanoscale features for magnesium that can improve its use in numerous orthopedic applications. PMID:23674891

  20. PREFACE: Self-organized nanostructures

    NASA Astrophysics Data System (ADS)

    Rousset, Sylvie; Ortega, Enrique

    2006-04-01

    In order to fabricate ordered arrays of nanostructures, two different strategies might be considered. The `top-down' approach consists of pushing the limit of lithography techniques down to the nanometre scale. However, beyond 10 nm lithography techniques will inevitably face major intrinsic limitations. An alternative method for elaborating ultimate-size nanostructures is based on the reverse `bottom-up' approach, i.e. building up nanostructures (and eventually assemble them to form functional circuits) from individual atoms or molecules. Scanning probe microscopies, including scanning tunnelling microscopy (STM) invented in 1982, have made it possible to create (and visualize) individual structures atom by atom. However, such individual atomic manipulation is not suitable for industrial applications. Self-assembly or self-organization of nanostructures on solid surfaces is a bottom-up approach that allows one to fabricate and assemble nanostructure arrays in a one-step process. For applications, such as high density magnetic storage, self-assembly appears to be the simplest alternative to lithography for massive, parallel fabrication of nanostructure arrays with regular sizes and spacings. These are also necessary for investigating the physical properties of individual nanostructures by means of averaging techniques, i.e. all those using light or particle beams. The state-of-the-art and the current developments in the field of self-organization and physical properties of assembled nanostructures are reviewed in this issue of Journal of Physics: Condensed Matter. The papers have been selected from among the invited and oral presentations of the recent summer workshop held in Cargese (Corsica, France, 17-23 July 2005). All authors are world-renowned in the field. The workshop has been funded by the Marie Curie Actions: Marie Curie Conferences and Training Courses series named `NanosciencesTech' supported by the VI Framework Programme of the European Community, by

  1. Basic morphofunctional features of pharmaceutic leech (Hirudo verbana Carena, 1820) tissues in various forms of response after hirudotherapeutic procedures.

    PubMed

    Frolov, Aleksandr K; Litvinenko, Raisa A

    2015-01-01

    It is analyzed morphofunctional features of Hirudo verbana tissues on histological sections in order to determine the possible causes of their partial death after hirudotherapeutic procedure. In the study was taken 4 groups of leeches: hungry (control), healthy well-fed, well-fed that vomited blood and well-fed dead. Morphofunctional changes in midgut of healthy well-fed H. verbana compared to the hungry are the changes of epithelium height through stretching eaten blood. In well-fed that vomited blood and well-fed dead leeches in the intestinal epithelium were observed degenerative processes that are accompanied by a decrease in the height of the epithelium, its partial desquamation. Botryoidal tissue of hungry leeches is in an inactive state, in healthy well-fed ones it responds with an increased physiological vascularization, activation of some botryoidal granulocytes with an increase in their average size, on receipt of the products of digestion. Activation of some botryoidal granulocytes, without a significant increase in their sizes, in well-fed leeches that vomited eaten blood and well-fed dead leeches, with increased infiltration of the adjacent connective tissue lymphocyte- and macrophage-like cells, amebocytes and granulocytes indicates the development of pathological processes, which are resulting in immunological conflict between eaten human blood and leeches' tissue microenvironment.

  2. Recognizing and predicting thioether bridges formed by lanthionine and β-methyllanthionine in lantibiotics using a random forest approach with feature selection.

    PubMed

    Wang, ShaoPeng; Zhang, Yu-Hang; Zhang, Ning; Chen, Lei; Huang, Tao; Cai, Yu-Dong

    2017-03-10

    Lantibiotics, which are usually produced from Gram-positive bacteria, are regarded as one type of special bacteriocins. Lantibiotics have unsaturated amino acid residues formed by lanthionine (Lan) and β-methyllanthionine (MeLan) residues as a ring structure in the peptide. They are derived from the serine and threonine residues and are essential to preventing the growth of other similar strains. In this pioneering work, we firstly proposed a machine learning method to recognize and predict the Lan and MeLan residues in the protein sequences of lantibiotics. We adopted maximal relevance minimal redundancy (mRMR) and incremental feature selection (IFS) to select optimal features and random forest (RF) to build classifiers determining the Lan and MeLan residues. A 10-fold cross-validation test was performed on the classifiers to evaluate their predicted performances. As a result, the Matthew's correlation coefficient (MCC) values for predicting the Lan and MeLan residues were 0.813 and 0.769, respectively. Our constructed RF classifiers were shown to have a reliable ability to recognize Lan and MeLan residues from lantibiotic sequences. Furthermore, three other methods, Dagging, the nearest neighbor algorithm (NNA) and sequential minimal optimization (SMO) were also utilized to build classifiers to predict Lan and MeLan residues for comparison. Analysis was also performed on the optimal features, and the relationships between the optimal features and their biological importance were provided. We believe the selected optimal features and analysis in this work will contribute to a better understanding of the sequence and structural features around the Lan and MeLan residues. It could provide useful information and practical suggestions for experimental and computational methods toward exploring the biological features of such special residues in lantibiotics. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Chemical and environmental implications of visible and near-infrared spectral features of salt crusts formed from different brines.

    PubMed

    Howari, Fares M

    2004-04-01

    This work describes a laboratory experiment intended to study the formation and spectral reflectance properties of stratified salt crusts that cause severe environmental degradations to soil and water resources in arid regions. Salt crusts were prepared by evaporating three types of saline solutions consisting of i) NaCl - Na2SO4, ii) Na2SO4 - MgSO4, and iii) NaCl - MgSO4 at an initial concentrations of 50 mmol L(-1). They were examined for evaporite mineralogy using X-ray diffraction, optical and reflected microscopes, and for spectral reflectance with a high-resolution spectroradiometer (GER 3700) in the visible and near-infrared regions (400-2500 nm). The study documented chemical and environmental implications of the spectral properties of salt formed from the studied saline-systems. The reported results can be used to understand remotely sensed signatures of salt crusts and their implications.

  4. Optical design including characteristics of manufactured nanostructures

    NASA Astrophysics Data System (ADS)

    Wächter, Christoph; Müller, Martin; Förster, Erik; Oliva, Maria; Michaelis, Dirk

    2013-09-01

    Micro- and nanostructures enable specific optical functionalities, which rely on diffractive effects or effective medium features, depending on pattern dimension and wavelength. Performance predictions of optical systems which make use of nanostructured materials require having an accurate description of these materials ready to hand within the optical design. At the one hand, nanostructure characteristics which result from rigorous electromagnetic modeling can be used for the optical design. At the other hand, manufactured nanostructures may deviate from their idealized geometry, which will affect the performance of the optical system, wherein these artificial structures will be used. Thus, detailed optical characterization of the micro- or nanostructure functionality is prerequisite for accurate optical design and performance prediction. To this end, several characterization techniques can be applied depending on the scope of the optical design, finally. We report on a general route to include all accessible and required optical information about the nanostructured material within a corresponding model of the nanostructure as a specific optical component which can be used within a ray-trace engine, finally. This is illustrated by a meta-material with asymmetric transmission properties in some more detail.

  5. Sequence-specific recognition of DNA nanostructures.

    PubMed

    Rusling, David A; Fox, Keith R

    2014-05-15

    DNA is the most exploited biopolymer for the programmed self-assembly of objects and devices that exhibit nanoscale-sized features. One of the most useful properties of DNA nanostructures is their ability to be functionalized with additional non-nucleic acid components. The introduction of such a component is often achieved by attaching it to an oligonucleotide that is part of the nanostructure, or hybridizing it to single-stranded overhangs that extend beyond or above the nanostructure surface. However, restrictions in nanostructure design and/or the self-assembly process can limit the suitability of these procedures. An alternative strategy is to couple the component to a DNA recognition agent that is capable of binding to duplex sequences within the nanostructure. This offers the advantage that it requires little, if any, alteration to the nanostructure and can be achieved after structure assembly. In addition, since the molecular recognition of DNA can be controlled by varying pH and ionic conditions, such systems offer tunable properties that are distinct from simple Watson-Crick hybridization. Here, we describe methodology that has been used to exploit and characterize the sequence-specific recognition of DNA nanostructures, with the aim of generating functional assemblies for bionanotechnology and synthetic biology applications.

  6. Stacked mechanical nanogenerator comprising piezoelectric semiconducting nanostructures and Schottky conductive contacts

    DOEpatents

    Wang, Zhong L.; Xu, Sheng

    2011-08-23

    An electric power generator includes a first conductive layer, a plurality of semiconducting piezoelectric nanostructures, a second conductive layer and a plurality of conductive nanostructures. The first conductive layer has a first surface from which the semiconducting piezoelectric nanostructures extend. The second conductive layer has a second surface and is parallel to the first conductive layer so that the second surface faces the first surface of the first conductive layer. The conductive nanostructures depend downwardly therefrom. The second conductive layer is spaced apart from the first conductive layer at a distance so that when a force is applied, the semiconducting piezoelectric nanostructures engage the conductive nanostructures so that the piezoelectric nanostructures bend, thereby generating a potential difference across the at semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the semiconducting piezoelectric nanostructures and the conductive nanostructures.

  7. Metallic Nanostructures Based on DNA Nanoshapes.

    PubMed

    Shen, Boxuan; Tapio, Kosti; Linko, Veikko; Kostiainen, Mauri A; Toppari, Jari Jussi

    2016-08-10

    Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable development of DNA-based nanostructures has provided many successful methods and realizations for these needs, such as chemical DNA metallization via seeding or ionization, as well as DNA-guided lithography and casting of metallic nanoparticles by DNA molds. These methods offer high resolution, versatility and throughput and could enable the fabrication of arbitrarily-shaped structures with a 10-nm feature size, thus bringing novel applications into view. In this review, we cover the evolution of DNA-based metallic nanostructures, starting from the metallized double-stranded DNA for electronics and progress to sophisticated plasmonic structures based on DNA origami objects.

  8. Metallic Nanostructures Based on DNA Nanoshapes

    PubMed Central

    Shen, Boxuan; Tapio, Kosti; Linko, Veikko; Kostiainen, Mauri A.; Toppari, Jari Jussi

    2016-01-01

    Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable development of DNA-based nanostructures has provided many successful methods and realizations for these needs, such as chemical DNA metallization via seeding or ionization, as well as DNA-guided lithography and casting of metallic nanoparticles by DNA molds. These methods offer high resolution, versatility and throughput and could enable the fabrication of arbitrarily-shaped structures with a 10-nm feature size, thus bringing novel applications into view. In this review, we cover the evolution of DNA-based metallic nanostructures, starting from the metallized double-stranded DNA for electronics and progress to sophisticated plasmonic structures based on DNA origami objects. PMID:28335274

  9. Unusual Features of Vaccinia Virus Extracellular Virion Form Neutralization Resistance Revealed in Human Antibody Responses to the Smallpox Vaccine

    PubMed Central

    Benhnia, Mohammed Rafii-El-Idrissi; Maybeno, Matthew; Blum, David; Aguilar-Sino, Rowena; Matho, Michael; Meng, Xiangzhi; Head, Steven; Felgner, Philip L.; Zajonc, Dirk M.; Koriazova, Lilia; Kato, Shinichiro; Burton, Dennis R.; Xiang, Yan; Crowe, James E.; Peters, Bjoern

    2013-01-01

    The extracellular virion form (EV) of vaccinia virus (VACV) is essential for viral pathogenesis and is difficult to neutralize with antibodies. Why this is the case and how the smallpox vaccine overcomes this challenge remain incompletely understood. We previously showed that high concentrations of anti-B5 antibodies are insufficient to directly neutralize EV (M. R. Benhnia, et al., J. Virol. 83:1201–1215, 2009). This allowed for at least two possible interpretations: covering the EV surface is insufficient for neutralization, or there are insufficient copies of B5 to allow anti-B5 IgG to cover the whole surface of EV and another viral receptor protein remains active. We endeavored to test these possibilities, focusing on the antibody responses elicited by immunization against smallpox. We tested whether human monoclonal antibodies (MAbs) against the three major EV antigens, B5, A33, and A56, could individually or together neutralize EV. While anti-B5 or anti-A33 (but not anti-A56) MAbs of appropriate isotypes were capable of neutralizing EV in the presence of complement, a mixture of anti-B5, anti-A33, and anti-A56 MAbs was incapable of directly neutralizing EV, even at high concentrations. This remained true when neutralizing the IHD-J strain, which lacks a functional version of the fourth and final known EV surface protein, A34. These immunological data are consistent with the possibility that viral proteins may not be the active component of the EV surface for target cell binding and infectivity. We conclude that the protection afforded by the smallpox vaccine anti-EV response is predominantly mediated not by direct neutralization but by isotype-dependent effector functions, such as complement recruitment for antibodies targeting B5 and A33. PMID:23152530

  10. Effects of organic ligands, electrostatic and magnetic interactions in formation of colloidal and interfacial inorganic nanostructures.

    PubMed

    Khomutov, G B; Koksharov, Yu A

    2006-09-25

    This paper discusses effects of organic ligands, electrostatic and magnetic interactions involved in morphological control of chemically synthesized inorganic nanostructures including colloid and planar systems. The special attention was concentrated on noble metal (gold and palladium) nanoparticles and nanostructures formed at the gas-liquid interface. The analysis of experimental data showed that electrostatic and ligand-related interactions influence very strongly on the metal nanostructure morphology. The hydrophobicity of ligand, charge and binding affinity to inorganic phase are important factors influencing the morphology of inorganic nanostructures formed in a layer at the gas/liquid interface by the interfacial synthesis method. The important point of this method is the quasi two-dimensional character of reaction area and possibilities to realize ultimately thin and anisotropic dynamic monomolecular reaction system with two-dimensional diffusion and interactions of precursors, intermediates and ligands resulting in planar growth and organization of inorganic nanoparticles and nanostructures in the plain of Langmuir monolayer. The morphology of resulting inorganic nanostructures can be controlled efficiently by variations of growth conditions via changes in state and composition of interfacial planar reaction media with the same precursor, and by variations of composition of adjacent bulk phases. The extreme anisotropy and heterogeneity of two-dimensional interfacial reaction system allows creating conditions when growing inorganic particles floating on the aqueous phase surface interact selectively with hydrophobic water-insoluble ligands in interfacial monolayer or with hydrophilic bulk-phase ligands, or at the same time with ligands of different nature present in monolayer and in aqueous phase. The spatial anisotropy of interfacial reaction system and non-homogeneity of ligand binding to inorganic phase gives possibilities for growth of integrated

  11. Laser Fabricated Nanostructures on Vanadium Foils

    SciTech Connect

    Farkas, B.; Fuele, M.; Nanai, L.; Balint, A. M.

    2011-10-03

    In this work we present our results concerning to the nanostructure generation on vanadium surfaces by ultrashort pulsed laser irradiation. The melting free formation of these structures is very important in many fields of science and industry too. We obtain that the nanostructure forming process on vanadium surface is Stransky Krastanov type. The surface covering and the nano-tower shape are depending on the ambient of the laser matter reaction.

  12. Nanostructured Block Copolymer Solutions and Composites: Mechanical and Structural Properties

    NASA Astrophysics Data System (ADS)

    Walker, Lynn

    2015-03-01

    Self-assembled block copolymer templates are used to control the nanoscale structure of materials that would not otherwise order in solution. In this work, we have developed a technique to use close-packed cubic and cylindrical mesophases of a thermoreversible block copolymer (PEO-PPO-PEO) to impart spatial order on dispersed nanoparticles. The thermoreversible nature of the template allows for the dispersion of particles synthesized outside the template. This feature extends the applicability of this templating method to many particle-polymer systems, including proteins, and also permits a systematic evaluation of the impact of design parameters on the structure and mechanical properties of the nanocomposites. The criteria for forming co-crystals have been characterized using small-angle scatting and the mechanical properties of these soft crystals determined. Numerous crystal structures have been reported for the block copolymer system and we have taken advantage of several to generate soft co-crystals. The result of this templating is spatially ordered nanoparticle arrays embedded within the block copolymer nanostructure. These soft materials can be shear aligned into crystals with long range order and this shear alignment is discussed. Finally, the dynamics of nanoparticles within the nanostructured material are characterized with fluorescence recovery after photobleaching (FRAP). The applications and general behavior of these nanostructured hydrogels are outlined.

  13. Correlations in infrared spectra of nanostructures based on mixed oxides

    NASA Astrophysics Data System (ADS)

    Averin, I. A.; Karmanov, A. A.; Moshnikov, V. A.; Pronin, I. A.; Igoshina, S. E.; Sigaev, A. P.; Terukov, E. I.

    2015-12-01

    This paper has presented experimental data on the infrared spectroscopic investigation of nanostructures based on mixed oxides. Nanostructures in the form of porous thin films deposited on oxidized single- crystal silicon substrates have been synthesized by the sol-gel method. The qualitative composition of film-forming sols and the related nanostructures has been examined. Correlations relating the coefficient of transmission of infrared radiation through the materials under investigation and their quantitative composition have been established. The processes occurring during the annealing of the nanostructures in the temperature range from 100 to 600°C have been analyzed.

  14. @AuAg nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Rina; Soni, R. K.

    2014-09-01

    Bimetallic and trimetallic nanoparticles have attracted significant attention in recent times due to their enhanced electrochemical and catalytic properties compared to monometallic nanoparticles. The numerical calculations using Mie theory has been carried out for three-layered metal nanoshell dielectric-metal-metal (DMM) system consisting of a particle with a dielectric core (Al@Al2O3), a middle metal Ag (Au) layer and an outer metal Au (Ag) shell. The results have been interpreted using plasmon hybridization theory. We have also prepared Al@Al2O3@Ag@Au and Al@Al2O3@AgAu triple-layered core-shell or alloy nanostructure by two-step laser ablation method and compared with calculated results. The synthesis involves temporal separations of Al, Ag, and Au deposition for step-by-step formation of triple-layered core-shell structure. To form Al@Ag nanoparticles, we ablated silver for 40 min in aluminium nanoparticle colloidal solution. As aluminium oxidizes easily in water to form alumina, the resulting structure is core-shell Al@Al2O3. The Al@Al2O3 particle acts as a seed for the incoming energetic silver particles for multilayered Al@Al2O3@Ag nanoparticles is formed. The silver target was then replaced by gold target and ablation was carried out for different ablation time using different laser energy for generation of Al@Al2O3@Ag@Au core-shell or Al@Al2O3@AgAu alloy. The formation of core-shell and alloy nanostructure was confirmed by UV-visible spectroscopy. The absorption spectra show shift in plasmon resonance peak of silver to gold in the range 400-520 nm with increasing ablation time suggesting formation of Ag-Au alloy in the presence of alumina particles in the solution.

  15. Dynamics of Nanostructures at Surfaces

    SciTech Connect

    Schmid, Andreas K.

    2001-02-28

    Currently, much effort is being devoted to the goal of achieving useful nanotechnologies, which depend on the ability to control and manipulate things on a very small scale. One promising approach to the construction of nanostructures is 'self-assembly', which means that under suitable conditions desired nanostructures might form automatically due to physical and chemical forces. Remarkably, the forces controlling such self-assembly mechanisms are only poorly understood, even though highly successful examples of self-assembly are known in nature (e.g., complex biochemical machinery regularly self-assembles in the conditions inside living cells). This talk will highlight basic measurements of fundamental forces governing the dynamics of nanostructures at prototypical metal surfaces. We use advanced surface microscopy techniques to track the motions of very small structures in real time and up to atomic resolution. One classic example of self-organized nanostructures are networks of surface dislocations (linear crystal defects). The direct observation of thermally activated atomic motions of dislocations in a reconstructed gold surface allows us to measure the forces stabilizing the remarkable long-range order of this nanostructure. In another example, the rapid migration of nano-scale tin crystals deposited on a pure copper surface was traced to an atomic repulsion between tin atoms absorbed on the crystal surface and bronze alloy formed in the footprint of the tin crystals. It is intriguing to consider the clusters as simple chemo-mechanical energy transducers, essentially tiny linear motors built of 100,000 Sn atoms. We can support this view by providing estimates of the power and energy-efficiency of these nano-motors.

  16. Study of the chemical chelates and anti-microbial effect of some metal ions in nanostructural form on the efficiency of antibiotic therapy "norfloxacin drug"

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Hawary, W. F.; Mohamed, Mahmoud A.

    2012-04-01

    This paper has reviewed the chemical and biological impact resulting from the interaction between norfloxacin (norH) antibiotic drug and two lanthanide (lanthanum(III) and cerium(III)) metal ions, which prepared in normal and nano-features. La(III) and Ce(III) complexes were synthesized with chemical formulas [La(nor)3]·3H2O and [Ce(nor)3]·2H2O. Lanthanum and cerium(III) ions coordinated toward norH with a hexadentate geometry. The norH acts as deprotonated bidentate ligand through the oxygen atom of carbonyl group and the oxygen atom of carboxylic group. Elemental analysis, FT-IR spectral, electrical conductivity, thermal analysis (TG/DTA), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurements have been used to characterize the mentioned isolated complexes. The Coats-Redfern and Horowitz-Metzger integral methods are used to estimate the kinetic parameters for the major successive steps detectable in the TG curve. The brightness side in this study is to take advantage for the preparation and characterization of single phases of La2O3 and CeO2 nanoparticles using urea as precursors via a solid-state decomposition procedure. The norH ligand in comparison with both cases (normal and nano-particles) of lanthanide complexes were screened against for antibacterial (Escherichia Coli, Staphylococcus Aureus, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal (Aspergillus Flavus and Candida Albicans) activities. The highest antibacterial and antifungal activities data of the nano-particles complexes were observed with more potent than the free norH and normal lanthanide complexes.

  17. Bulk Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Koch, C. C.; Langdon, T. G.; Lavernia, E. J.

    2017-09-01

    This paper will address three topics of importance to bulk nanostructured materials. Bulk nanostructured materials are defined as bulk solids with nanoscale or partly nanoscale microstructures. This category of nanostructured materials has historical roots going back many decades but has relatively recent focus due to new discoveries of unique properties of some nanoscale materials. Bulk nanostructured materials are prepared by a variety of severe plastic deformation methods, and these will be reviewed. Powder processing to prepare bulk nanostructured materials requires that the powders be consolidated by typical combinations of pressure and temperature, the latter leading to coarsening of the microstructure. The thermal stability of nanostructured materials will also be discussed. An example of bringing nanostructured materials to applications as structural materials will be described in terms of the cryomilling of powders and their consolidation.

  18. Versatile pattern generation of periodic, high aspect ratio Si nanostructure arrays with sub-50-nm resolution on a wafer scale.

    PubMed

    Ho, Jian-Wei; Wee, Qixun; Dumond, Jarrett; Tay, Andrew; Chua, Soo-Jin

    2013-12-01

    We report on a method of fabricating variable patterns of periodic, high aspect ratio silicon nanostructures with sub-50-nm resolution on a wafer scale. The approach marries step-and-repeat nanoimprint lithography (NIL) and metal-catalyzed electroless etching (MCEE), enabling near perfectly ordered Si nanostructure arrays of user-defined patterns to be controllably and rapidly generated on a wafer scale. Periodic features possessing circular, hexagonal, and rectangular cross-sections with lateral dimensions down to sub-50 nm, in hexagonal or square array configurations and high array packing densities up to 5.13 × 107 structures/mm2 not achievable by conventional UV photolithography are fabricated using this top-down approach. By suitably tuning the duration of catalytic etching, variable aspect ratio Si nanostructures can be formed. As the etched Si pattern depends largely on the NIL mould which is patterned by electron beam lithography (EBL), the technique can be used to form patterns not possible with self-assembly methods, nanosphere, and interference lithography for replication on a wafer scale. Good chemical resistance of the nanoimprinted mask and adhesion to the Si substrate facilitate good pattern transfer and preserve the smooth top surface morphology of the Si nanostructures as shown in TEM. This approach is suitable for generating Si nanostructures of controlled dimensions and patterns, with high aspect ratio on a wafer level suitable for semiconductor device production.

  19. Versatile pattern generation of periodic, high aspect ratio Si nanostructure arrays with sub-50-nm resolution on a wafer scale

    NASA Astrophysics Data System (ADS)

    Ho, Jian-Wei; Wee, Qixun; Dumond, Jarrett; Tay, Andrew; Chua, Soo-Jin

    2013-12-01

    We report on a method of fabricating variable patterns of periodic, high aspect ratio silicon nanostructures with sub-50-nm resolution on a wafer scale. The approach marries step-and-repeat nanoimprint lithography (NIL) and metal-catalyzed electroless etching (MCEE), enabling near perfectly ordered Si nanostructure arrays of user-defined patterns to be controllably and rapidly generated on a wafer scale. Periodic features possessing circular, hexagonal, and rectangular cross-sections with lateral dimensions down to sub-50 nm, in hexagonal or square array configurations and high array packing densities up to 5.13 × 107 structures/mm2 not achievable by conventional UV photolithography are fabricated using this top-down approach. By suitably tuning the duration of catalytic etching, variable aspect ratio Si nanostructures can be formed. As the etched Si pattern depends largely on the NIL mould which is patterned by electron beam lithography (EBL), the technique can be used to form patterns not possible with self-assembly methods, nanosphere, and interference lithography for replication on a wafer scale. Good chemical resistance of the nanoimprinted mask and adhesion to the Si substrate facilitate good pattern transfer and preserve the smooth top surface morphology of the Si nanostructures as shown in TEM. This approach is suitable for generating Si nanostructures of controlled dimensions and patterns, with high aspect ratio on a wafer level suitable for semiconductor device production.

  20. Versatile pattern generation of periodic, high aspect ratio Si nanostructure arrays with sub-50-nm resolution on a wafer scale

    PubMed Central

    2013-01-01

    We report on a method of fabricating variable patterns of periodic, high aspect ratio silicon nanostructures with sub-50-nm resolution on a wafer scale. The approach marries step-and-repeat nanoimprint lithography (NIL) and metal-catalyzed electroless etching (MCEE), enabling near perfectly ordered Si nanostructure arrays of user-defined patterns to be controllably and rapidly generated on a wafer scale. Periodic features possessing circular, hexagonal, and rectangular cross-sections with lateral dimensions down to sub-50 nm, in hexagonal or square array configurations and high array packing densities up to 5.13 × 107 structures/mm2 not achievable by conventional UV photolithography are fabricated using this top-down approach. By suitably tuning the duration of catalytic etching, variable aspect ratio Si nanostructures can be formed. As the etched Si pattern depends largely on the NIL mould which is patterned by electron beam lithography (EBL), the technique can be used to form patterns not possible with self-assembly methods, nanosphere, and interference lithography for replication on a wafer scale. Good chemical resistance of the nanoimprinted mask and adhesion to the Si substrate facilitate good pattern transfer and preserve the smooth top surface morphology of the Si nanostructures as shown in TEM. This approach is suitable for generating Si nanostructures of controlled dimensions and patterns, with high aspect ratio on a wafer level suitable for semiconductor device production. PMID:24289275

  1. The influence of silver nanostructures formed in situ in silica sol-gel derived films on the rate of Förster resonance energy transfer.

    PubMed

    Holmes-Smith, A Sheila; McDowell, Gary R; Toury, Marion; McLoskey, David; Hungerford, Graham

    2012-02-01

    The efficiency of Förster resonance energy transfer (FRET) can be enhanced in the presence of a metal. Herein, we demonstrate the increased efficiency for a novel model sensor system where FRET is shown to occur between Rhodamine 6G in the bulk sol-gel matrix and Texas Red, which is held a fixed distance away by covalent attachment onto a silane spacer. Silver colloids are formed using light to initiate the reduction of a silver salt, which can be achieved at controlled locations within the film. Both the fluorescence intensity and lifetime maps and analysis indicate that an enhanced FRET efficiency has been achieved in the presence of silver nanoparticles. An increase in efficiency of 1.2-1.5 times is demonstrated depending on the spacer used. The novelty of our approach lies in the method of silver-nanoparticle formation, which allows for the accurate positioning of the silver nanoparticles and hence selective fluorescence enhancement within a biocompatible host material. Our work gives a practical demonstration of metal-enhanced FRET and demonstrates the ability of such systems to be developed for molecular-recognition applications that could find use in lab-on-a-chip technologies.

  2. Hematite nanostructuring using electrohydrodynamic lithography

    NASA Astrophysics Data System (ADS)

    Boudoire, Florent; Toth, Rita; Heier, Jakob; Braun, Artur; Constable, Edwin C.

    2014-06-01

    Tailoring hematite thin film nanostructure is particularly interesting since this oxide's function is closely related to its structure, for example when implemented as a photoanode in water splitting solar cells. In this study, electrohydrodynamic destabilization was designed to grow hematite nanodroplets with morphologies controlled by a master electrode. A polymer/iron salt film was destabilized by electrohydrodynamic destabilization and the resulting structures were pyrolysed to achieve crystalline α-Fe2O3 nanodroplets of 30 nm height and 70 nm radius. NEXAFS spectroscopy proved that the structures contain ferrihydrite, which is converted into hematite during pyrolysis, while the polymer was decomposed. Homogeneous nanoparticle precipitation in the bulk of the polymer, due to encapsulation of the iron precursor in the polymer matrix, is accounted for the good preservation of the structures. This study represents the first step towards the use of electrohydrodynamic destabilization for nanostructuring of hematite thin films, with a control over the feature size.

  3. Sub-Tg features of glasses formed by cooling glycerol under pressure - Additional incompatibility of vibrational with configurational states in the depressurized, high density glass

    NASA Astrophysics Data System (ADS)

    Andersson, Ove; Johari, G. P.

    2016-11-01

    The vibrational state of a glass is naturally incompatible with its configurational state, which makes the glass structurally unstable. When a glass is kept at constant temperature, both the vibrational and configurational states of a glass change with time until it becomes metastable (equilibrium) liquid and the two states become compatible. The process, known as structural relaxation, occurs at a progressively higher rate during heating, and the properties of a glass change accordingly. We add to this incompatibility by depressurizing a glass that had been formed by cooling a liquid under a high pressure, p, and then investigate the effects of the added incompatibility by studying thermal conductivity, κ , and the heat capacity per unit volume ρ Cp of the depressurized glass. We use glycerol for the purpose and study first the changes in the features of κ and of ρ Cp during glass formation on cooling under a set of different p. We then partially depressurize the glass and study the effect of the p-induced instability on the features of κ and ρ Cp as the glass is isobarically heated to the liquid state. At a given low p, the glass configuration that was formed by cooling at high-p had a higher κ than the glass configuration that was formed by cooling at a low p. The difference is more when the glass is formed at a higher p and/or is depressurized to a lower p. On heating at a low p, its κ decreases before its glass-liquid transition range is reached. The effect is the opposite of the increase in κ observed on heating a glass at the same p under which it was formed. It is caused by thermally assisted loss of the added incompatibility of configurational and vibrational states of a high-p formed glass kept at low p. If a glass formed under a low-p is pressurized and then heated under high p, it would show the opposite effect, i.e., its κ would first increase to its high p value before its glass-to-liquid transition range.

  4. Repairable, nanostructured biomimetic hydrogels

    NASA Astrophysics Data System (ADS)

    Firestone, M.; Brombosz, S.; Grubjesic, S.

    2013-03-01

    Proteins facilitate many key cellular processes, including signal recognition and energy transduction. The ability to harness this evolutionarily-optimized functionality could lead to the development of protein-based systems useful for advancing alternative energy storage and conversion. The future of protein-based, however, requires the development of materials that will stabilize, order and control the activity of the proteins. Recently we have developed a synthetic approach for the preparation of a durable biomimetic chemical hydrogel that can be reversibly swollen in water. The matrix has proven ideal for the stable encapsulation of both water- and membrane-soluble proteins. The material is composed of an aqueous dispersion of a diacrylate end-derivatized PEO-PPO-PEO macromer, a saturated phospholipid and a zwitterionic co-surfactant that self-assembles into a nanostructured physical gel at room temperature as determined by X-ray scattering. The addition of a water soluble PEGDA co-monomer and photoinitator does not alter the self-assembled structure and UV irradiation serves to crosslink the acrylate end groups on the macromer with the PEGDA forming a network within the aqueous domains as determined by FT-IR. More recently we have begun to incorporate reversible crosslinks employing Diels-Alder chemistry, allowing for the extraction and replacement of inactive proteins. The ability to replenish the materials with active, non-denatured forms of protein is an important step in advancing these materials for use in nanostructured devices This work was supported by the Office of Basic Energy Sciences, Division of Materials Sciences, USDoE under Contract No. DE-AC02-06CH11357.

  5. Ultrahard magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Sahota, P. K.; Liu, Y.; Skomski, R.; Manchanda, P.; Zhang, R.; Franchin, M.; Fangohr, H.; Hadjipanayis, G. C.; Kashyap, A.; Sellmyer, D. J.

    2012-04-01

    The performance of hard-magnetic nanostructures is investigated by analyzing the size and geometry dependence of thin-film hysteresis loops. Compared to bulk magnets, weight and volume are much less important, but we find that the energy product remains the main figure of merit down to very small features sizes. However, hysteresis loops are much easier to control on small length scales, as epitomized by Fe-Co-Pt thin films with magnetizations of up to 1.78 T and coercivities of up to 2.52 T. Our numerical and analytical calculations show that the feature size and geometry have a big effect on the hysteresis loop. Layered soft regions, especially if they have a free surface, are more harmful to coercivity and energy product than spherical inclusions. In hard-soft nanocomposites, an additional complication is provided by the physical properties of the hard phases. For a given soft phase, the performance of a hard-soft composite is determined by the parameter (Ms - Mh)/Kh.

  6. Nanostructured composite reinforced material

    DOEpatents

    Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  7. Wedging transfer of nanostructures.

    PubMed

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

    2010-05-12

    We report a versatile water-based method for transferring nanostructures onto surfaces of various shapes and compositions. The transfer occurs through the intercalation of a layer of water between a hydrophilic substrate and a hydrophobic nanostructure (for example, graphene flakes, carbon nanotubes, metallic nanostructures, quantum dots, etc.) locked within a hydrophobic polymer thin film. As a result, the film entrapping the nanostructure is lifted off and floats at the air-water interface. The nanostructure can subsequently be deposited onto a target substrate by the removal of the water and the dissolution of the polymeric film. We show examples where graphene flakes and patterned metallic nanostructures are precisely transferred onto a specific location on a variety of patterned substrates, even on top of curved objects such as microspheres. The method is simple to use, fast, and does not require advanced equipment.

  8. Optical properties of chiral nanostructures

    NASA Astrophysics Data System (ADS)

    Cecilia, Noguez; Román-Velázquez, Carlos E.; Garzón, Ignacio L.

    2004-03-01

    We present a computational model to study the optical properties chiral nanostructures[1] . In this work the nanostructures of interest are composed by N atoms, where each one is represented by a polarizable point dipole located at theposition of the atom. We assume that the dipole located is characterized by a polarizability. The nanostructure is excited by a circularly polarized incident wave, such that, each dipole is subject to a total electric field due to: (i) the incident radiation field, plus (ii) the radiation field resulting from all of the other induced dipoles. Once we solve the complex-linear equations, the dipole moment on each atom in the cluster can be determined and we can find the extinction cross section of the whole nanoparticle. Circular dichroism (CD) spectra of chiral bare and thiol-passivated gold nanoclusters have been calculated within the dipole approximation. The calculated CD spectra show features that allow us to distinguish between clusters with different indexes of chirality. The main factor responsible of the differences in the CD lineshapes is the distribution of interatomic distances that characterize the chiral cluster geometry. These results provide theoretical support for the quantification of chirality and its measurement, using the CD lineshapes of chiral metal nanoclusters. [1] C. E. Roman-Velazquez, et al., J. of Phys. Chem. B (Letter) 107, 12035 (2003) This work has been partly supported by DGAPA-UNAM grants No. IN104201 and IN104402, and by CONACyT grant 36651-E.

  9. Resonant electron tunneling and related charging phenomena in metal-oxide- p +-Si nanostructures

    NASA Astrophysics Data System (ADS)

    Vexler, M. I.; Kareva, G. G.; Illarionov, Yu. Yu.; Grekhov, I. V.

    2016-11-01

    The j- V characteristics of the Al/thermal or electrochemical SiO2(2-4 nm)/heavily doped p +-Si nanostructures operating as a resonant-tunneling diode were measured and theoretically analyzed. The characteristics have specific features in the form of current steps and peaks, which are caused by electron transport between the silicon valence band and metal through discrete levels of the quantum well formed by the p +-Si conduction band and SiO2/ p +-Si interface. Resonant tunneling through the surface state levels and the appearance of a charge near this interface under certain conditions are discussed.

  10. The relationship between personality organization as assessed by theory-driven profiles of the Dutch Short Form of the MMPI and self-reported features of personality organization.

    PubMed

    Eurelings-Bontekoe, Elisabeth H M; Luyten, Patrick; Remijsen, Mila; Koelen, Jurrijn

    2010-11-01

    In this study, we investigated the relationships between features of personality organization (PO) as assessed by theory driven profiles of the Dutch Short Form of the MMPI (DSFM; Luteijn & Kok, 1985) and 2 self-report measures of personality pathology, that is, the Dutch Inventory of Personality Organization (Berghuis, Kamphuis, Boedijn, & Verheul, 2009) and the Dutch Schizotypy Personality Questionnaire-Revised (Vollema & Hoijtink, 2000), in a sample of 190 outpatient psychiatric patients. Results showed that the single scales of all 3 measures segregated into 2 theoretically expected and meaningful dimensions, that is, a dimension assessing severity of personality pathology and an introversion/extraversion dimension. Theory-driven combinations of single DSFM subscales as a measure of level of PO distinguished characteristics of patients at various levels of PO in theoretically predicted ways. Results also suggest that structural personality pathology may not be fully captured by self-report measures.

  11. EDITORIAL: Focus on Nanostructured Soft Matter

    NASA Astrophysics Data System (ADS)

    Reineker, Peter; Schülz, Michael

    2004-01-01

    Nanostructures in general are playing a more and more important role in the physics and chemistry of condensed matter systems including both hard and soft materials. This Focus Issue concentrates particularly on recent developments in Nanostructured Soft Matter Systems. Many interesting questions related to both fundamental and applied research in this field have arisen. Some of them are connected to the chemical reactions that take place during the irreversible formation of soft matter systems. Others refer to the theoretical and experimental investigations of structures and topologies of `nanostructured soft matter', e.g. heterogeneous polymers and polymer networks, or soft matter at low dimensions or in constrained geometries. Additional research has also been devoted to the dynamics of other complex nanostructured systems, such as the structure formation on the basis of polymer systems and polyelectrolytes, and several kinds of phase transitions on nano- and microscales. The contributions collected here present the most up-to-date research results on all of these topics. New Journal of Physics, as an electronic journal, is perfectly suited for the presentation of the complex results that the experimental and theoretical investigations reported here yield. The articles that will follow provide a number of excellent examples of the use of animations, movies and colour features for the added benefit of the reader. Focus on Nanostructured Soft Matter Contents Phase separation kinetics in compressible polymer solutions: computer simulation of the early stages Peter Virnau, Marcus Müller, Luis González MacDowell and Kurt Binder Spectral dynamics in the B800 band of LH2 from Rhodospirillum molischianum: a single-molecule study Clemens Hofmann, Thijs J Aartsma, Hartmut Michel and Jürgen Köhler Adsorption of polyacrylic acid on self-assembled monolayers investigated by single-molecule force spectroscopy Claudia Friedsam, Aránzazu Del Campo Bécares, Ulrich Jonas

  12. Design principles for rapid folding of knotted DNA nanostructures.

    PubMed

    Kočar, Vid; Schreck, John S; Čeru, Slavko; Gradišar, Helena; Bašić, Nino; Pisanski, Tomaž; Doye, Jonathan P K; Jerala, Roman

    2016-02-18

    Knots are some of the most remarkable topological features in nature. Self-assembly of knotted polymers without breaking or forming covalent bonds is challenging, as the chain needs to be threaded through previously formed loops in an exactly defined order. Here we describe principles to guide the folding of highly knotted single-chain DNA nanostructures as demonstrated on a nano-sized square pyramid. Folding of knots is encoded by the arrangement of modules of different stability based on derived topological and kinetic rules. Among DNA designs composed of the same modules and encoding the same topology, only the one with the folding pathway designed according to the 'free-end' rule folds efficiently into the target structure. Besides high folding yield on slow annealing, this design also folds rapidly on temperature quenching and dilution from chemical denaturant. This strategy could be used to design folding of other knotted programmable polymers such as RNA or proteins.

  13. To the understanding of the formation of the droplet-epitaxial III-V based nanostructures

    SciTech Connect

    Nemcsics, Ákos

    2014-05-15

    In this work, we discuss the evolution of the self-assembling III-V based nanostructures. These nano-structures were prepared by droplet epitaxial technique. The different nanostructures such as quantum dot, quantum ring, double quantum ring, or nanohole form similarly from an initial Ga droplet but under different substrate temperature and various arsenic pressures. Started from few atomic courses, we give here a qualitative description of the key processes for all of the aforementioned nanostructures.

  14. Interstellar Analogs from Defective Carbon Nanostructures Account for Interstellar Extinction

    NASA Astrophysics Data System (ADS)

    Tan, Zhenquan; Chihara, Hiroki; Koike, Chiyoe; Abe, Hiroya; Kaneko, Kenji; Sato, Kazuyoshi; Ohara, Satoshi

    2010-11-01

    Because interstellar dust is closely related to the evolution of matter in the galactic environment and many other astrophysical phenomena, the laboratory synthesis of interstellar dust analogs has received significant attention over the past decade. To simulate the ultraviolet (UV) interstellar extinction feature at 217.5 nm originating from carbonaceous interstellar dust, many reports focused on the UV absorption properties of laboratory-synthesized interstellar dust analogs. However, no general relation has been established between UV interstellar extinction and artificial interstellar dust analogs. Here, we show that defective carbon nanostructures prepared by high-energy collisions exhibit a UV absorption feature at 220 nm which we suggest accounts for the UV interstellar extinction at 217.5 nm. The morphology of some carbon nanostructures is similar to that of nanocarbons discovered in the Allende meteorite. The similarity between the absorption feature of the defective carbon nanostructures and UV interstellar extinction indicates a strong correlation between the defective carbon nanostructures and interstellar dust.

  15. INTERSTELLAR ANALOGS FROM DEFECTIVE CARBON NANOSTRUCTURES ACCOUNT FOR INTERSTELLAR EXTINCTION

    SciTech Connect

    Tan, Zhenquan; Abe, Hiroya; Sato, Kazuyoshi; Ohara, Satoshi; Chihara, Hiroki; Koike, Chiyoe; Kaneko, Kenji

    2010-11-15

    Because interstellar dust is closely related to the evolution of matter in the galactic environment and many other astrophysical phenomena, the laboratory synthesis of interstellar dust analogs has received significant attention over the past decade. To simulate the ultraviolet (UV) interstellar extinction feature at 217.5 nm originating from carbonaceous interstellar dust, many reports focused on the UV absorption properties of laboratory-synthesized interstellar dust analogs. However, no general relation has been established between UV interstellar extinction and artificial interstellar dust analogs. Here, we show that defective carbon nanostructures prepared by high-energy collisions exhibit a UV absorption feature at 220 nm which we suggest accounts for the UV interstellar extinction at 217.5 nm. The morphology of some carbon nanostructures is similar to that of nanocarbons discovered in the Allende meteorite. The similarity between the absorption feature of the defective carbon nanostructures and UV interstellar extinction indicates a strong correlation between the defective carbon nanostructures and interstellar dust.

  16. Main clinical features of the three mapped autosomal recessive limb-girdle muscular dystrophies and estimated proportion of each form in 13 Brazilian families.

    PubMed Central

    Passos-Bueno, M R; Moreira, E S; Marie, S K; Bashir, R; Vasquez, L; Love, D R; Vainzof, M; Iughetti, P; Oliveira, J R; Bakker, E; Strachan, T; Bushby, K; Zatz, M

    1996-01-01

    Autosomal recessive limb-girdle muscular dystrophies (AR LGMD) represent a group of muscle diseases with a wide spectrum of clinical signs, varying from very severe to mild. Four different loci that when mutated cause the AR LGMD phenotype have been mapped or cloned or both: in two of them the linked families seem to have a relatively mild phenotype (LGMD2a and LGMD2b), in the third one the reported linked families show a more severe clinical course (LGMD2c), while mutations in the fourth locus may cause severe or mild phenotypes (LGMD2d). The relative proportion of each of these genetic forms among the LGMD families and whether there are other genes that when mutated cause this phenotype is unknown. The closest available informative markers for each of the mapped AR LGMD genes have been tested in 13 Brazilian families with at least three affected patients. The findings from the present report confirm non-allelic heterogeneity for LGMD and suggest that in our population about 33% of the LGMD families are caused by mutations in the 15q gene, 33% in the 2p gene, 17% by mutations in the adhalin gene, and less than 10% may be by mutations at the 13q locus. They also suggest that there is at least one other gene responsible for this phenotype. In addition, the main clinical features of the different forms are discussed. PMID:8929943

  17. Analysing and Manipulating the Nanostructure of Geopolymers

    NASA Astrophysics Data System (ADS)

    Provis, J. L.; Hajimohammadi, A.; Rees, C. A.; van Deventer, J. S. J.

    Geopolymer concretes are currently being commercialised in Australia and elsewhere around the world, with a view towards enhancing the sustainability of the world’s construction industry. The fundamental geopolymer binder is an aluminosilicate gel which displays key structural features on every length scale from Ångstroms up to centimetres, meaning that multiscale analysis is key to the development of a detailed understanding of geopolymer formation and performance. Here, we present results from investigations of geopolymer nanostructure, focusing on the use of infrared spectroscopy as an analytical tool. The effects of different combinations of precursors in geopolymer formation provides critical information, in particular with regard to the rate of reaction and its impact on the final distribution of elements and structures within the geopolymer binder. Formulations are designed so that the same composition is obtained by the use of precursors which release their constituent elements at very different rates under alkaline attack during geopolymerisation, and this provides essential information regarding the role of different elements in forming strong and durable geopolymer structures. Seeding the geopolymer mixture with very low doses of oxide nanoparticles presents several unexpected effects, both in terms of reaction kinetics and also in altering the nature of the zeolitic crystallites formed within the predominantly X-ray amorphous geopolymer binder.

  18. Structural features underlying the selective cleavage of a novel exo-type maltose-forming amylase from Pyrococcus sp. ST04.

    PubMed

    Park, Kwang-Hyun; Jung, Jong-Hyun; Park, Sung-Goo; Lee, Myeong-Eun; Holden, James F; Park, Cheon-Seok; Woo, Eui-Jeon

    2014-06-01

    A novel maltose-forming α-amylase (PSMA) was recently found in the hyperthermophilic archaeon Pyrococcus sp. ST04. This enzyme shows <13% amino-acid sequence identity to other known α-amylases and displays a unique enzymatic property in that it hydrolyzes both α-1,4-glucosidic and α-1,6-glucosidic linkages of substrates, recognizing only maltose units, in an exo-type manner. Here, the crystal structure of PSMA at a resolution of 1.8 Å is reported, showing a tight ring-shaped tetramer with monomers composed of two domains: an N-domain (amino acids 1-341) with a typical GH57 family (β/α)7-barrel fold and a C-domain (amino acids 342-597) composed of α-helical bundles. A small closed cavity observed in proximity to the catalytic residues Glu153 and Asp253 at the domain interface has the appropriate volume and geometry to bind a maltose unit, accounting for the selective exo-type maltose hydrolysis of the enzyme. A narrow gate at the putative subsite +1 formed by residue Phe218 and Phe452 is essential for specific cleavage of glucosidic bonds. The closed cavity at the active site is connected to a short substrate-binding channel that extends to the central hole of the tetramer, exhibiting a geometry that is significantly different from classical maltogenic amylases or β-amylases. The structural features of this novel exo-type maltose-forming α-amylase provide a molecular basis for its unique enzymatic characteristics and for its potential use in industrial applications and protein engineering.

  19. Conserved Surface Features Form the Double-stranded RNA Binding Site of Non-structural Protein 1 (NS1) from Influenza A and B Viruses

    SciTech Connect

    Yin,C.; Khan, J.; Swapna, G.; Ertekin, A.; Krug, R.; Tong, L.; Montelione, G.

    2007-01-01

    Influenza A viruses cause a highly contagious respiratory disease in humans and are responsible for periodic widespread epidemics with high mortality rates. The influenza A virus NS1 protein (NS1A) plays a key role in countering host antiviral defense and in virulence. The 73-residue N-terminal domain of NS1A (NS1A-(1-73)) forms a symmetric homodimer with a unique six-helical chain fold. It binds canonical A-form double-stranded RNA (dsRNA). Mutational inactivation of this dsRNA binding activity of NS1A highly attenuates virus replication. Here, we have characterized the unique structural features of the dsRNA binding surface of NS1A-(1-73) using NMR methods and describe the 2.1-{angstrom} x-ray crystal structure of the corresponding dsRNA binding domain from human influenza B virus NS1B-(15-93). These results identify conserved dsRNA binding surfaces on both NS1A-(1-73) and NS1B-(15-93) that are very different from those indicated in earlier 'working models' of the complex between dsRNA and NS1A-(1-73). The combined NMR and crystallographic data reveal highly conserved surface tracks of basic and hydrophilic residues that interact with dsRNA. These tracks are structurally complementary to the polyphosphate backbone conformation of A-form dsRNA and run at an {approx}45{sup o} angle relative to the axes of helices {alpha}2/{alpha}2'. At the center of this dsRNA binding epitope, and common to NS1 proteins from influenza A and B viruses, is a deep pocket that includes both hydrophilic and hydrophobic amino acids. This pocket provides a target on the surface of the NS1 protein that is potentially suitable for the development of antiviral drugs targeting both influenza A and B viruses.

  20. Conserved surface features form the double-stranded RNA binding site of non-structural protein 1 (NS1) from influenza A and B viruses.

    PubMed

    Yin, Cuifeng; Khan, Javed A; Swapna, G V T; Ertekin, Asli; Krug, Robert M; Tong, Liang; Montelione, Gaetano T

    2007-07-13

    Influenza A viruses cause a highly contagious respiratory disease in humans and are responsible for periodic widespread epidemics with high mortality rates. The influenza A virus NS1 protein (NS1A) plays a key role in countering host antiviral defense and in virulence. The 73-residue N-terminal domain of NS1A (NS1A-(1-73)) forms a symmetric homodimer with a unique six-helical chain fold. It binds canonical A-form double-stranded RNA (dsRNA). Mutational inactivation of this dsRNA binding activity of NS1A highly attenuates virus replication. Here, we have characterized the unique structural features of the dsRNA binding surface of NS1A-(1-73) using NMR methods and describe the 2.1-A x-ray crystal structure of the corresponding dsRNA binding domain from human influenza B virus NS1B-(15-93). These results identify conserved dsRNA binding surfaces on both NS1A-(1-73) and NS1B-(15-93) that are very different from those indicated in earlier "working models" of the complex between dsRNA and NS1A-(1-73). The combined NMR and crystallographic data reveal highly conserved surface tracks of basic and hydrophilic residues that interact with dsRNA. These tracks are structurally complementary to the polyphosphate backbone conformation of A-form dsRNA and run at an approximately 45 degrees angle relative to the axes of helices alpha2/alpha2'. At the center of this dsRNA binding epitope, and common to NS1 proteins from influenza A and B viruses, is a deep pocket that includes both hydrophilic and hydrophobic amino acids. This pocket provides a target on the surface of the NS1 protein that is potentially suitable for the development of antiviral drugs targeting both influenza A and B viruses.

  1. When lithography meets self-assembly: a review of recent advances in the directed assembly of complex metal nanostructures on planar and textured surfaces

    NASA Astrophysics Data System (ADS)

    Hughes, Robert A.; Menumerov, Eredzhep; Neretina, Svetlana

    2017-07-01

    One of the foremost challenges in nanofabrication is the establishment of a processing science that integrates wafer-based materials, techniques, and devices with the extraordinary physicochemical properties accessible when materials are reduced to nanoscale dimensions. Such a merger would allow for exacting controls on nanostructure positioning, promote cooperative phenomenon between adjacent nanostructures and/or substrate materials, and allow for electrical contact to individual or groups of nanostructures. With neither self-assembly nor top-down lithographic processes being able to adequately meet this challenge, advancements have often relied on a hybrid strategy that utilizes lithographically-defined features to direct the assembly of nanostructures into organized patterns. While these so-called directed assembly techniques have proven viable, much of this effort has focused on the assembly of periodic arrays of spherical or near-spherical nanostructures comprised of a single element. Work directed toward the fabrication of more complex nanostructures, while still at a nascent stage, has nevertheless demonstrated the possibility of forming arrays of nanocubes, nanorods, nanoprisms, nanoshells, nanocages, nanoframes, core-shell structures, Janus structures, and various alloys on the substrate surface. In this topical review, we describe the progress made in the directed assembly of periodic arrays of these complex metal nanostructures on planar and textured substrates. The review is divided into three broad strategies reliant on: (i) the deterministic positioning of colloidal structures, (ii) the reorganization of deposited metal films at elevated temperatures, and (iii) liquid-phase chemistry practiced directly on the substrate surface. These strategies collectively utilize a broad range of techniques including capillary assembly, microcontact printing, chemical surface modulation, templated dewetting, nanoimprint lithography, and dip-pen nanolithography and

  2. Vibron and phonon hybridization in dielectric nanostructures.

    PubMed

    Preston, Thomas C; Signorell, Ruth

    2011-04-05

    Plasmon hybridization theory has been an invaluable tool in advancing our understanding of the optical properties of metallic nanostructures. Through the prism of molecular orbital theory, it allows one to interpret complex structures as "plasmonic molecules" and easily predict and engineer their electromagnetic response. However, this formalism is limited to conducting particles. Here, we present a hybridization scheme for the external and internal vibrations of dielectric nanostructures that provides a straightforward understanding of the infrared signatures of these particles through analogy to existing hybridization models of both molecular orbitals and plasmons extending the range of applications far beyond metallic nanostructures. This method not only provides a qualitative understanding, but also allows for the quantitative prediction of vibrational spectra of complex nanoobjects from well-known spectra of their primitive building blocks. The examples of nanoshells illustrate how spectral features can be understood in terms of symmetry, number of nodal planes, and scale parameters.

  3. Silicon nanostructures for cancer diagnosis and therapy.

    PubMed

    Peng, Fei; Cao, Zhaohui; Ji, Xiaoyuan; Chu, Binbin; Su, Yuanyuan; He, Yao

    2015-01-01

    The emergence of nanotechnology suggests new and exciting opportunities for early diagnosis and therapy of cancer. During the recent years, silicon-based nanomaterials featuring unique properties have received great attention, showing high promise for myriad biological and biomedical applications. In this review, we will particularly summarize latest representative achievements on the development of silicon nanostructures as a powerful platform for cancer early diagnosis and therapy. First, we introduce the silicon nanomaterial-based biosensors for detecting cancer markers (e.g., proteins, tumor-suppressor genes and telomerase activity, among others) with high sensitivity and selectivity under molecular level. Then, we summarize in vitro and in vivo applications of silicon nanostructures as efficient nanoagents for cancer therapy. Finally, we discuss the future perspective of silicon nanostructures for cancer diagnosis and therapy.

  4. Nanostructured scaffolds for bone tissue engineering.

    PubMed

    Li, Xiaoming; Wang, Lu; Fan, Yubo; Feng, Qingling; Cui, Fu-Zhai; Watari, Fumio

    2013-08-01

    It has been demonstrated that nanostructured materials, compared with conventional materials, may promote greater amounts of specific protein interactions, thereby more efficiently stimulating new bone formation. It has also been indicated that, when features or ingredients of scaffolds are nanoscaled, a variety of interactions can be stimulated at the cellular level. Some of those interactions induce favorable cellular functions while others may leads to toxicity. This review presents the mechanism of interactions between nanoscaled materials and cells and focuses on the current research status of nanostructured scaffolds for bone tissue engineering. Firstly, the main requirements for bone tissue engineering scaffolds were discussed. Then, the mechanism by which nanoscaled materials promote new bone formation was explained, following which the current research status of main types of nanostructured scaffolds for bone tissue engineering was reviewed and discussed. Copyright © 2013 Wiley Periodicals, Inc.

  5. DNA nanostructure-based imaging probes and drug carriers.

    PubMed

    Zhan, Pengfei; Jiang, Qiao; Wang, Zhen-Gang; Li, Na; Yu, Haiyin; Ding, Baoquan

    2014-09-01

    Self-assembled DNA nanostructures are well-defined nanoscale shapes, with uniform sizes, precise spatial addressability, and excellent biocompatibility. With these features, DNA nanostructures show great potential for biomedical applications; various DNA-based biomedical imaging probes or payload delivery carriers have been developed. In this review, we summarize the recent developments of DNA-based nanostructures as tools for diagnosis and cancer therapy. The biological effects that are brought about by DNA nanostructures are highlighted by in vitro and in vivo imaging, antitumor drug delivery, and immunostimulatory therapy. The challenges and perspectives of DNA nanostructures in the field of nanomedicine are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Multifunctional nanostructured materials for multimodal cancer imaging and therapy.

    PubMed

    Liao, Jinfeng; Qi, Tingting; Chu, Bingyang; Peng, Jinrong; Luo, Feng; Qian, Zhiyong

    2014-01-01

    This paper reviews the recent research and development of multifunctional nanostructured materials for multimodal imaging and therapy. The biomedical applications for multifunctional imaging, diagnosis and therapy are discussed for several nanostructured materials such as polymeric nanoparticles, magnetic nanoparticles, gold nanomaterials, carbon materials, quantum dots and silica nanoparticles. Due to the unique features of nanostructured materials including the large surface area, structural diversity, multifunctionality, and long circulation time in blood, these materials have emerged as attractive preferences for optimized therapy. Multimodal imaging can be introduced to nanostructured materials for precise and fast diagnosis of cancer, which overcomes the shortcoming of single-imaging modality. Meanwhile, nanostructured materials can be also used to deliver therapeutic agents to the disease site in order to accomplish multimodal imaging and simultaneous diagnosis and therapy.

  7. Eco-friendly fabrication of Ag nanostructures using the seed extract of Pedalium murex, an ancient Indian medicinal plant: Histopathological effects on the Zika virus vector Aedes aegypti and inhibition of biofilm-forming pathogenic bacteria.

    PubMed

    Ishwarya, Ramachandran; Vaseeharan, Baskaralingam; Anuradha, Ramasamy; Rekha, Ravichandran; Govindarajan, Marimuthu; Alharbi, Naiyf S; Kadaikunnan, Shine; Khaled, Jamal M; Benelli, Giovanni

    2017-09-01

    The control of Zika virus mosquito vectors and well as the development of drugs in the fight against biofilm-forming microbial pathogens, are timely and important challenges in current bionanoscience. Here we focused on the eco-friendly fabrication of Ag nanostructures using the seed extract of Pedalium murex, an ancient Indian medicinal plant. Initial confirmation of Ag nanoparticles (AgNPs) production was showed by a color change from transparent to dark brown. The UV-Visible spectrum (476nm), X-ray diffraction peaks (101, 200, 220 and 311) and Fourier transform infrared spectroscopy shed light on the production of green-capped AgNPs. Morphological structure analysis using HR-TEM showed that the AgNPs were mostly hexagonal in shape with rough edges, and a size of 20-30nm. The larvicidal potential of P. murex seed extract and AgNPs fabricated using the P. murex seed extract (Pm-AgNPs) was tested on fourth instar mosquito larvae of the Zika virus vector Aedes aegypti. Maximum efficacy was achieved by Pm-AgNPs against Ae. aegypti after 24h (LC50 34.88; LC90 64.56mg/ml), if compared to the P. murex seed extract. Histopathological analyses showed severe damages to the hindgut and larval muscles in NPs-treated Ae. aegypti larvae. The sub-MIC concentrations of Pm-AgNPs exhibited significant anti-biofilm activity against Gram positive (Enterococcus faecalis, Staphylococcus aureus) and Gram negative (Shigella sonnei, Pseudomonas aeruginosa) bacterial pathogens, as showed by EPS and MTP assays. Light and CLSM microscopic studies highlighted a significant impact of P. murex seed extract and Pm-synthesized AgNPs on the surface topography and architecture of bacterial biofilm, both in Gram positive and Gram negative species. Overall, results reported here contribute to the development of reliable large-scale protocols for the green fabrication of effective mosquito larvicides and biofilm inhibitors. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Nanostructural Characteristics of Vacuum Cold-Sprayed Hydroxyapatite/Graphene-Nanosheet Coatings for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Huang, Jing; Li, Hua

    2014-10-01

    Development of novel biocompatible nanomaterials has provided insights into their potential biomedical applications. Bulk fabrication of the nanomaterials in the form of coatings remains challenging. Here, we report hydroxyapatite (HA)/graphene-nanosheet (GN) composite coatings deposited by vacuum cold spray (VCS). Significant shape changes of HA nanograins during the coating deposition were revealed. The nanostructural features of HA together with curvature alternation of GN gave rise to dense structures. Based on the microstructural characterization, a structure model was proposed to elucidate the nanostructural characteristics of the HA-GN nanocomposites. Results also showed that addition of GN significantly enhanced fracture toughness and elastic modulus of the HA-based coatings, which is presumably accounted for by crack bridging offered by GN in the composites. The VCS HA-GN coatings show potential for biomedical applications for the repair or replacement of hard tissues.

  9. Focused ion beam lithography for fabrication of suspended nanostructures on highly corrugated surfaces.

    PubMed

    Erdmanis, M; Sievilä, P; Shah, A; Chekurov, N; Ovchinnikov, V; Tittonen, I

    2014-08-22

    We propose a nanofabrication method that allows for patterning on extremely corrugated surfaces with micrometer-size features. The technique employs focused ion beam nanopatterning of ion-sensitive inorganic resists formed by atomic layer deposition at low temperature. The nanoscale resolution on corrugated surfaces is ensured by inherently large depth of focus of a focused ion beam system and very uniform resist coating. The utilized TiO₂ and Al₂O₃ resists show high selectivity in deep reactive ion etching and enable the release of suspended nanostructures by dry etching. We demonstrate the great flexibility of the process by fabricating suspended nanostructures on flat surfaces, inclined walls, and on the bottom of deep grooves.

  10. Self-assembling graphene-anthraquinone-2-sulphonate supramolecular nanostructures with enhanced energy density for supercapacitors

    NASA Astrophysics Data System (ADS)

    Gao, Lifang; Gan, Shiyu; Li, Hongyan; Han, Dongxue; Li, Fenghua; Bao, Yu; Niu, Li

    2017-07-01

    Boosting the energy density of capacitive energy storage devices remains a crucial issue for facilitating applications. Herein, we report a graphene-anthraquinone supramolecular nanostructure by self-assembly for supercapacitors. The sulfonated anthraquinone exhibits high water solubility, a π-conjugated structure and redox active features, which not only serve as a spacer to interact with and stabilize graphene but also introduce extra pseudocapacitance contributions. The formed nest-like three-dimensional (3D) nanostructure with further hydrothermal treatment enhances the accessibility of ion transfer and exposes the redox-active quinone groups in the electrolytes. A fabricated all-solid-state flexible symmetric device delivers a high specific capacitance of 398.5 F g-1 at 1 A g-1 (1.5 times higher than graphene), superior energy density (52.24 Wh kg-1 at about 1 kW kg-1) and good stability (82% capacitance retention after 10 000 cycles).

  11. Computer-Aided Production of Scaffolded DNA Nanostructures from Flat Sheet Meshes.

    PubMed

    Benson, Erik; Mohammed, Abdulmelik; Bosco, Alessandro; Teixeira, Ana I; Orponen, Pekka; Högberg, Björn

    2016-07-25

    The use of DNA as a nanoscale construction material has been a rapidly developing field since the 1980s, in particular since the introduction of scaffolded DNA origami in 2006. Although software is available for DNA origami design, the user is generally limited to architectures where finding the scaffold path through the object is trivial. Herein, we demonstrate the automated conversion of arbitrary two-dimensional sheets in the form of digital meshes into scaffolded DNA nanostructures. We investigate the properties of DNA meshes based on three different internal frameworks in standard folding buffer and physiological salt buffers. We then employ the triangulated internal framework and produce four 2D structures with complex outlines and internal features. We demonstrate that this highly automated technique is capable of producing complex DNA nanostructures that fold with high yield to their programmed configurations, covering around 70 % more surface area than classic origami flat sheets.

  12. Mueller matrix imaging ellipsometry for nanostructure metrology.

    PubMed

    Liu, Shiyuan; Du, Weichao; Chen, Xiuguo; Jiang, Hao; Zhang, Chuanwei

    2015-06-29

    In order to achieve effective process control, fast, inexpensive, nondestructive and reliable nanometer scale feature measurements are extremely useful in high-volume nanomanufacturing. Among the possible techniques, optical scatterometry is relatively ideal due to its high throughput, low cost, and minimal sample damage. However, this technique is inherently limited by the illumination spot size of the instrument and the low efficiency in construction of a map of the sample over a wide area. Aiming at these issues, we introduce conventional imaging techniques to optical scatterometry and combine them with Mueller matrix ellipsometry based scatterometry, which is expected to be a powerful tool for the measurement of nanostructures in future high-volume nanomanufacturing, and propose to apply Mueller matrix imaging ellipsometry (MMIE) for nanostructure metrology. Two kinds of nanostructures were measured using an in-house developed Mueller matrix imaging ellipsometer in this work. The experimental results demonstrate that we can achieve Mueller matrix measurement and analysis for nanostructures with pixel-sized illumination spots by using MMIE. We can also efficiently construct parameter maps of the nanostructures over a wide area with pixel-sized lateral resolution by performing parallel ellipsometric analysis for all the pixels of interest.

  13. Integration of nanostructured titania into microsystems

    NASA Astrophysics Data System (ADS)

    Abu Samah, Zuruzi

    2005-07-01

    This thesis describes research on a novel process to fabricate integrated nanostructured titanic (NST) features as functional components in microsystems devices. NST features were formed by oxidizing Ti films in aqueous hydrogen peroxide followed by thermal annealing. The oxidation kinetics and properties of NST formed were investigated. The process developed is compatible with current microelectronics manufacturing practices for Si and plastic substrates. Amorphous hydrated titanic gels form when hydrogen peroxide (H2 O2) reacts with Ti. Oxidation of a blanket (unpatterned) Ti surface with hydrogen peroxide results in a titanic layer with high crack density. In this study, NST was formed by reacting pre-patterned Ti thin films with H2O2 solution. Crack elimination was achieved when exposed Ti films were below a threshold dimension. Hydrated titanic gel crystallizes into anatase after annealing at 300°C for 8 hr. Crack elimination is thought to result from stress reduction in titanic gels due to patterning. Oxidation of Ti films occurs by nucleation and growth mechanism. During growth, oxidation of Ti films with thickness 50 nm and below proceeds at a constant rate until films are fully consumed. For Ti films with thickness 100 nm or thicker oxidation rate reduces significantly after a period of growth. This reduction is attributed to a change in mechanism controlling growth of the hydrated titania gel layer. Functionality of NST formed and compatibility of the process with current microelectronics manufacturing practices were demonstrated by exploring three applications. First, a prototype conductometric gas sensor was fabricated that used micrometer-scale NST pad arrays as sensing elements. This sensor is capable of detecting hydrogen and oxygen gas at concentration of a few parts per million (ppm). Second, micrometer scale Au-NST interpenetrating network nanocomposite contacts in micro-switches were fabricated by infiltrating NST features with Au using

  14. Nanostructured scaffolds for neural applications.

    PubMed

    Seidlits, Stephanie K; Lee, Jae Y; Schmidt, Christine E

    2008-04-01

    This review discusses the design of scaffolds having submicron and nanoscale features for neural-engineering applications. In particular, the goal is to create materials that can interface more intimately with individual neuronal cells, within both living tissues and in culture, by better mimicking the native extracellular environment. Scaffolds with nanoscale features have the potential to improve the specificity and accuracy of materials for a number of neural-engineering applications, ranging from neural probes for Parkinson's patients to guidance scaffolds for axonal regeneration in patients with traumatic nerve injuries. This review will highlight several techniques that are used to create nanostructured scaffolds, such as photolithography to create grooves for neurite guidance, electrospinning of fibrous matrices, self-assembly of 3D scaffolds from designer peptides and fabrication of conductive nanoscale materials. Most importantly, this review focuses on the effects of incorporating nanoscale architectures into these materials on neuronal and glial cell growth and function.

  15. Experimental Study of Water Droplet Vaporization on Nanostructured Surfaces

    NASA Astrophysics Data System (ADS)

    Padilla, Jorge, Jr.

    This dissertation summarizes results of an experimental exploration of heat transfer during vaporization of a water droplet deposited on a nanostructured surface at a temperature approaching and exceeding the Leidenfrost point for the surface and at lower surface temperatures 10-40 degrees C above the saturated temperature of the water droplet at approximately 101 kPa. The results of these experiments were compared to those performed on bare smooth copper and aluminum surfaces in this and other studies. The nanostructured surfaces were composed of a vast array of zinc oxide (ZnO) nanocrystals grown by hydrothermal synthesis on a smooth copper substrate having an average surface roughness of approximately 0.06 micrometer. Various nanostructured surface array geometries were produced on the copper substrate by performing the hydrothermal synthesis for 4, 10 and 24 hours. The individual nanostructures were randomly-oriented and, depending on hydrothermal synthesis time, had a mean diameter of about 500-700 nm, a mean length of 1.7-3.3 micrometers,and porosities of approximately 0.04-0.58. Surface wetting was characterized by macroscopic measurements of contact angle based on the droplet profile and calculations based on measurements of liquid film spread area. Scanning electron microscope imaging was used to document the nanoscale features of the surface before and after the experiments. The nanostructured surfaces grown by hydrothermal synthesis for 4 and 24 hours exhibited contact angles of approximately 10, whereas the surfaces grown for 10 hours were superhydrophilic, exhibiting contact angles typically less than 3 degrees. In single droplet deposition experiments at 101 kPa, a high-speed video camera was used to document the droplet-surface interaction. Distilled and degassed water droplets ranging in size from 2.5-4.0 mm were deposited onto the surface from heights ranging from approximately 0.2-8.1 cm, such that Weber numbers spanned a range of approximately 0

  16. Ions and carbon nanostructures

    NASA Astrophysics Data System (ADS)

    Gyulai, József; Tapasztó, Levente; Endre Horváth, Zsolt; Nemes-Incze, Péter; Osváth, Zoltán; Péter Biró, László

    2013-06-01

    First experiments on swift ion irradiation of highly oriented pyrolythic graphite led to formation of carbon nanotubes (CNT) at the cascade eruption points. CNT length was in the micron range, which corresponded to an explosive crystallization of the carbon plume with about sound velocity. Multiplicity of CNT walls depended on cascade density: single wall CNTs were formed for approx. 200 MeV Xe ions, while multiwall CNTs for Kr, Ne ions of similar energy. Ion beam created defects were clearly visible on scanning tunneling microscopy (STM) images with atomic resolution. Second part of the paper deals with results of ion irradiation to sensitize CNT-s to reach, e.g. gas sensing properties using mainly changes in electrical conductivity of the bunch of CNTs. A third part of the paper contains some results on irradiated graphene. A new nanolithography technique of graphene used STM as a tool for nanostructuring graphene with crystallographic orientation control and line width of the order of few nanometers. The process enables to produce few nm wide stripes with precise crystallographic orientation.

  17. Measuring Strong Nanostructures

    ScienceCinema

    Andy Minor

    2016-07-12

    Andy Minor of Berkeley Lab's National Center for Electron Microscopy explains measuring stress and strain on nanostructures with the In Situ Microscope. More information: http://newscenter.lbl.gov/press-relea...

  18. Measuring Strong Nanostructures

    SciTech Connect

    Andy Minor

    2008-10-16

    Andy Minor of Berkeley Lab's National Center for Electron Microscopy explains measuring stress and strain on nanostructures with the In Situ Microscope. More information: http://newscenter.lbl.gov/press-relea...

  19. Nanostructuring of PEG-fibrinogen polymeric scaffolds.

    PubMed

    Frisman, Ilya; Seliktar, Dror; Bianco-Peled, Havazelet

    2010-07-01

    Recent studies have shown that nanostructuring of scaffolds for tissue engineering has a major impact on their interactions with cells. The current investigation focuses on nanostructuring of a biocompatible, biosynthetic polymeric hydrogel scaffold made from crosslinked poly(ethylene glycol)-fibrinogen conjugates. Nanostructuring was achieved by the addition of the block copolymer Pluronic F127, which self-assembles into nanometric micelles at certain concentrations and temperatures. Cryo-transmission electron microscopy experiments detected F127 micelles, both embedded within PEGylated fibrinogen hydrogels and in solution. The density of the F127 micelles, as well as their ordering, increased with increasing block copolymer concentration. The mechanical properties of the nanostructured hydrogels were investigated using stress-sweep rheological testing. These tests revealed a correlation between the block copolymer concentration and the storage modulus of the composite hydrogels. In vitro cellular assays confirmed that the increased modulus of the hydrogels did not limit the ability of the cells to form extensions and become spindled within the three-dimensional (3-D) hydrogel culture environment. Thus, altering the nanostructure of the hydrogel may be used as a strategy to control cellular behavior in 3-D through changes in mechanical properties of the environment.

  20. Architectures for Nanostructured Batteries

    NASA Astrophysics Data System (ADS)

    Rubloff, Gary

    2013-03-01

    Heterogeneous nanostructures offer profound opportunities for advancement in electrochemical energy storage, particularly with regard to power. However, their design and integration must balance ion transport, electron transport, and stability under charge/discharge cycling, involving fundamental physical, chemical and electrochemical mechanisms at nano length scales and across disparate time scales. In our group and in our DOE Energy Frontier Research Center (www.efrc.umd.edu) we have investigated single nanostructures and regular nanostructure arrays as batteries, electrochemical capacitors, and electrostatic capacitors to understand limiting mechanisms, using a variety of synthesis and characterization strategies. Primary lithiation pathways in heterogeneous nanostructures have been observed to include surface, interface, and both isotropic and anisotropic diffusion, depending on materials. Integrating current collection layers at the nano scale with active ion storage layers enhances power and can improve stability during cycling. For densely packed nanostructures as required for storage applications, we investigate both ``regular'' and ``random'' architectures consistent with transport requirements for spatial connectivity. Such configurations raise further important questions at the meso scale, such as dynamic ion and electron transport in narrow and tortuous channels, and the role of defect structures and their evolution during charge cycling. Supported as part of the Nanostructures for Electrical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001160

  1. A Novel Nanofabrication Technique of Silicon-Based Nanostructures

    NASA Astrophysics Data System (ADS)

    Meng, Lingkuan; He, Xiaobin; Gao, Jianfeng; Li, Junjie; Wei, Yayi; Yan, Jiang

    2016-11-01

    A novel nanofabrication technique which can produce highly controlled silicon-based nanostructures in wafer scale has been proposed using a simple amorphous silicon (α-Si) material as an etch mask. SiO2 nanostructures directly fabricated can serve as nanotemplates to transfer into the underlying substrates such as silicon, germanium, transistor gate, or other dielectric materials to form electrically functional nanostructures and devices. In this paper, two typical silicon-based nanostructures such as nanoline and nanofin have been successfully fabricated by this technique, demonstrating excellent etch performance. In addition, silicon nanostructures fabricated above can be further trimmed to less than 10 nm by combing with assisted post-treatment methods. The novel nanofabrication technique will be expected a new emerging technology with low process complexity and good compatibility with existing silicon integrated circuit and is an important step towards the easy fabrication of a wide variety of nanoelectronics, biosensors, and optoelectronic devices.

  2. A Novel Nanofabrication Technique of Silicon-Based Nanostructures.

    PubMed

    Meng, Lingkuan; He, Xiaobin; Gao, Jianfeng; Li, Junjie; Wei, Yayi; Yan, Jiang

    2016-12-01

    A novel nanofabrication technique which can produce highly controlled silicon-based nanostructures in wafer scale has been proposed using a simple amorphous silicon (α-Si) material as an etch mask. SiO2 nanostructures directly fabricated can serve as nanotemplates to transfer into the underlying substrates such as silicon, germanium, transistor gate, or other dielectric materials to form electrically functional nanostructures and devices. In this paper, two typical silicon-based nanostructures such as nanoline and nanofin have been successfully fabricated by this technique, demonstrating excellent etch performance. In addition, silicon nanostructures fabricated above can be further trimmed to less than 10 nm by combing with assisted post-treatment methods. The novel nanofabrication technique will be expected a new emerging technology with low process complexity and good compatibility with existing silicon integrated circuit and is an important step towards the easy fabrication of a wide variety of nanoelectronics, biosensors, and optoelectronic devices.

  3. Shape-Controlled Growth of Carbon Nanostructures: Yield and Mechanism.

    PubMed

    Ma, Yao; Sun, Xiao; Yang, Nianjun; Xia, Junhai; Zhang, Lei; Jiang, Xin

    2015-08-24

    Carbon nanostructures with precisely controlled shapes are difficult materials to synthesize. A facet-selective-catalytic process was thus proposed to synthesize polymer-linked carbon nanostructures with different shapes, covering straight carbon nanofiber, carbon nano Y-junction, carbon nano-hexapus, and carbon nano-octopus. A thermal chemical vapor deposition process was applied to grow these multi-branched carbon nanostructures at temperatures lower than 350 °C. Cu nanoparticles were utilized as the catalyst and acetylene as the reaction gas. The growth of those multi-branched nanostructures was realized through the selective growth of polymer-like sheets on certain indexed facets of Cu catalyst. The vapor-facet-solid (VFS) mechanism, a new growth mode, has been proposed to interpret such a growth in the steps of formation, diffusion, and coupling of carbon-containing oligomers, as well as their final precipitation to form nanostructures on the selective Cu facets.

  4. Nanoscale growth and patterning of inorganic oxides using DNA nanostructure templates.

    PubMed

    Surwade, Sumedh P; Zhou, Feng; Wei, Bryan; Sun, Wei; Powell, Anna; O'Donnell, Christina; Yin, Peng; Liu, Haitao

    2013-05-08

    We describe a method to form custom-shaped inorganic oxide nanostructures by using DNA nanostructure templates. We show that a DNA nanostructure can modulate the rate of chemical vapor deposition of SiO2 and TiO2 with nanometer-scale spatial resolution. The resulting oxide nanostructure inherits its shape from the DNA template. This method generates both positive-tone and negative-tone patterns on a wide range of substrates and is compatible with conventional silicon nanofabrication processes. Our result opens the door to the use of DNA nanostructures as general-purpose templates for high-resolution nanofabrication.

  5. Vertical stacking of three-dimensional nanostructures via an aerosol lithography for advanced optical applications.

    PubMed

    Lee, Kiwoong; Choi, Hoseop; Kim, Dae Seong; Jang, Min Seok; Choi, Mansoo

    2017-09-29

    In this report, we introduce a method utilizing ion-assisted aerosol lithography (IAAL) to stack 3D nanostructures vertically. The stacked 3D nanostructures exhibit extraordinary optical properties: the double layer 3D nanostructures show more than 5-fold increased surface enhanced Raman scattering (SERS) intensities compared to their single layer counterpart. This unusual enhancement of Raman intensity implies the existence of additional vertical hotspots formed by interlayer cavity effects between the lower and upper nanostructures. Allowing for full 3-dimensional control in nanofabrication, this work provides a reliable way to create complex-shaped advanced optical nanostructures with non-intuitive bulk optical properties. © 2017 IOP Publishing Ltd.

  6. Light management for photovoltaics using high-index nanostructures

    NASA Astrophysics Data System (ADS)

    Brongersma, Mark L.; Cui, Yi; Fan, Shanhui

    2014-05-01

    High-performance photovoltaic cells use semiconductors to convert sunlight into clean electrical power, and transparent dielectrics or conductive oxides as antireflection coatings. A common feature of these materials is their high refractive index. Whereas high-index materials in a planar form tend to produce a strong, undesired reflection of sunlight, high-index nanostructures afford new ways to manipulate light at a subwavelength scale. For example, nanoscale wires, particles and voids support strong optical resonances that can enhance and effectively control light absorption and scattering processes. As such, they provide ideal building blocks for novel, broadband antireflection coatings, light-trapping layers and super-absorbing films. This Review discusses some of the recent developments in the design and implementation of such photonic elements in thin-film photovoltaic cells.

  7. Interlocked DNA nanostructures controlled by a reversible logic circuit

    PubMed Central

    Li, Tao; Lohmann, Finn; Famulok, Michael

    2014-01-01

    DNA nanostructures constitute attractive devices for logic computing and nanomechanics. An emerging interest is to integrate these two fields and devise intelligent DNA nanorobots. Here we report a reversible logic circuit built on the programmable assembly of a double-stranded (ds) DNA [3]pseudocatenane that serves as a rigid scaffold to position two separate branched-out head-motifs, a bimolecular i-motif and a G-quadruplex. The G-quadruplex only forms when preceded by the assembly of the i-motif. The formation of the latter, in turn, requires acidic pH and unhindered mobility of the head-motif containing dsDNA nanorings with respect to the central ring to which they are interlocked, triggered by release oligodeoxynucleotides. We employ these features to convert the structural changes into Boolean operations with fluorescence labelling. The nanostructure behaves as a reversible logic circuit consisting of tandem YES and AND gates. Such reversible logic circuits integrated into functional nanodevices may guide future intelligent DNA nanorobots to manipulate cascade reactions in biological systems. PMID:25229207

  8. Interlocked DNA nanostructures controlled by a reversible logic circuit.

    PubMed

    Li, Tao; Lohmann, Finn; Famulok, Michael

    2014-09-17

    DNA nanostructures constitute attractive devices for logic computing and nanomechanics. An emerging interest is to integrate these two fields and devise intelligent DNA nanorobots. Here we report a reversible logic circuit built on the programmable assembly of a double-stranded (ds) DNA [3]pseudocatenane that serves as a rigid scaffold to position two separate branched-out head-motifs, a bimolecular i-motif and a G-quadruplex. The G-quadruplex only forms when preceded by the assembly of the i-motif. The formation of the latter, in turn, requires acidic pH and unhindered mobility of the head-motif containing dsDNA nanorings with respect to the central ring to which they are interlocked, triggered by release oligodeoxynucleotides. We employ these features to convert the structural changes into Boolean operations with fluorescence labelling. The nanostructure behaves as a reversible logic circuit consisting of tandem YES and AND gates. Such reversible logic circuits integrated into functional nanodevices may guide future intelligent DNA nanorobots to manipulate cascade reactions in biological systems.

  9. Formation of silicon nanostructures with a combination of spacer technology and deep reactive ion etching

    PubMed Central

    2012-01-01

    A new method of fabricating high aspect ratio nanostructures in silicon without the use of sub-micron lithographic technique is reported. The proposed method comprises two important steps including the use of CMOS spacer technique to form silicon nitride nanostructure masking followed by deep reactive ion etching (DRIE) of the silicon substrate to form the final silicon nanostructures. Silicon dioxide is used as the sacrificial layer to form the silicon nitride nanostructures. With DRIE a high etch selectivity of 50:1 between silicon and silicon nitride was achieved. The use of the spacer technique is particularly advantageous where self-aligned nanostructures with potentially unlimited lengths are formed without the need of submicron lithographic tools and resist materials. With this method, uniform arrays of 100 nm silicon nanostructures which are at least 4 μm tall with aspect ratio higher than 40 were successfully fabricated. PMID:22672745

  10. Elongated nanostructures for radial junction solar cells.

    PubMed

    Kuang, Yinghuan; Vece, Marcel Di; Rath, Jatindra K; Dijk, Lourens van; Schropp, Ruud E I

    2013-10-01

    In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

  11. Elongated nanostructures for radial junction solar cells

    NASA Astrophysics Data System (ADS)

    Kuang, Yinghuan; Di Vece, Marcel; Rath, Jatindra K.; van Dijk, Lourens; Schropp, Ruud E. I.

    2013-10-01

    In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

  12. DNA Nanostructures-Mediated Molecular Imprinting Lithography.

    PubMed

    Tian, Cheng; Kim, Hyojeong; Sun, Wei; Kim, Yunah; Yin, Peng; Liu, Haitao

    2017-01-24

    This paper describes the fabrication of polymer stamps using DNA nanostructure templates. This process creates stamps having diverse nanoscale features with dimensions ranging from several tens of nanometers to micrometers. DNA nanostructures including DNA nanotubes, stretched λ-DNA, two-dimensional (2D) DNA brick crystals with three-dimensional (3D) features, hexagonal DNA 2D arrays, and triangular DNA origami were used as master templates to transfer patterns to poly(methyl methacrylate) and poly(l-lactic acid) with high fidelity. The resulting polymer stamps were used as molds to transfer the pattern to acryloxy perfluoropolyether polymer. This work establishes an approach to using self-assembled DNA templates for applications in soft lithography.

  13. Nanostructures having high performance thermoelectric properties

    DOEpatents

    Yang, Peidong; Majumdar, Arunava; Hochbaum, Allon I.; Chen, Renkun; Delgado, Raul Diaz

    2015-12-22

    The invention provides for a nanostructure, or an array of such nanostructures, each comprising a rough surface, and a doped or undoped semiconductor. The nanostructure is an one-dimensional (1-D) nanostructure, such a nanowire, or a two-dimensional (2-D) nanostructure. The nanostructure can be placed between two electrodes and used for thermoelectric power generation or thermoelectric cooling.

  14. Nanostructures having high performance thermoelectric properties

    DOEpatents

    Yang, Peidong; Majumdar, Arunava; Hochbaum, Allon I; Chen, Renkun; Delgado, Raul Diaz

    2014-05-20

    The invention provides for a nanostructure, or an array of such nanostructures, each comprising a rough surface, and a doped or undoped semiconductor. The nanostructure is an one-dimensional (1-D) nanostructure, such a nanowire, or a two-dimensional (2-D) nanostructure. The nanostructure can be placed between two electrodes and used for thermoelectric power generation or thermoelectric cooling.

  15. Conductance fluctuations in nanostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Ningjia

    1997-12-01

    In this Ph.D thesis the conductance fluctuations of different physical origins in semi-conductor nanostructures were studied using both diagrammatic analytical methods and large scale numerical techniques. In the "mixed" transport regime where both mesoscopic and ballistic features play a role, for the first time I have analytically calculated the non-universal conductance fluctuations. This mixed regime is reached when impurities are distributed near the walls of a quantum wire, leaving the center region ballistic. I have discovered that the existence of a ballistic region destroys the universal conductance fluctuations. The crossover behavior of the fluctuation amplitude from the usual quasi-1D situation to that of the mixed regime is clearly revealed, and the role of various length scales are identified. My analytical predictions were confirmed by a direct numerical simulation by evaluating the Landauer formula. In another direction, I have made several studies of conductance or resistance oscillations and fluctuations in systems with artificial impurities in the ballistic regime. My calculation gave explanations of all the experimental results concerning the classical focusing peaks of the resistance versus magnetic field, the weak localization peak in a Sinai billiard system, the formation of a chaotic billiard, and predicted certain transport features which were indeed found experimentally. I have further extended the calculation to study the Hall resistance in a four-terminal quantum dot in which there is an antidot array. From my numerical data I analyzed the classical paths of electron motion and its quantum oscillations. The results compare well with recent experimental studies on similar systems. Since these billiard systems could provide quantum chaotic dynamics, I have made a detailed study of the consequence of such dynamics. In particular I have investigated the resonant transmission of electrons in these chaotic systems, and found that the level

  16. Nonlinear photoluminescence spectrum of single gold nanostructures.

    PubMed

    Knittel, Vanessa; Fischer, Marco P; de Roo, Tjaard; Mecking, Stefan; Leitenstorfer, Alfred; Brida, Daniele

    2015-01-27

    We investigate the multiphoton photoluminescence characteristics of gold nanoantennas fabricated from single crystals and polycrystalline films. By exciting these nanostructures with ultrashort pulses tunable in the near-infrared range, we observe distinct features in the broadband photoluminescence spectrum. By comparing antennas of different crystallinity and shape, we demonstrate that the nanoscopic geometry of plasmonic devices determines the shape of the emission spectra. Our findings rule out the contribution of the gold band structure in shaping the photoluminescence.

  17. The nanostructure problem

    SciTech Connect

    Billinge, S.

    2010-03-22

    Diffraction techniques are making progress in tackling the difficult problem of solving the structures of nanoparticles and nanoscale materials. The great gift of x-ray crystallography has made us almost complacent in our ability to locate the three-dimensional coordinates of atoms in a crystal with a precision of around 10{sup -4} nm. However, the powerful methods of crystallography break down for structures in which order only extends over a few nanometers. In fact, as we near the one hundred year mark since the birth of crystallography, we face a resilient frontier in condensed matter physics: our inability to routinely and robustly determine the structure of complex nanostructured and amorphous materials. Knowing the structure and arrangement of atoms in a solid is so fundamental to understanding its properties that the topic routinely occupies the early chapters of every solid-state physics textbook. Yet what has become clear with the emergence of nanotechnology is that diffraction data alone may not be enough to uniquely solve the structure of nanomaterials. As part of a growing effort to incorporate the results of other techniques to constrain x-ray refinements - a method called 'complex modeling' which is a simple but elegant approach for combining information from spectroscopy with diffraction data to solve the structure of several amorphous and nanostructured materials. Crystallography just works, so we rarely question how and why this is so, yet understanding the physics of diffraction can be very helpful as we consider the nanostructure problem. The relationship between the electron density distribution in three dimensions (i.e., the crystal structure) and an x-ray diffraction pattern is well established: the measured intensity distribution in reciprocal space is the square of the Fourier transform of the autocorrelation function <{rho}(r){rho}(r+r')> of the electron density distribution {rho}(r). The fact that we get the autocorrelation function

  18. Self-replication: Nanostructure evolution

    NASA Astrophysics Data System (ADS)

    Simmel, Friedrich C.

    2017-10-01

    DNA origami nanostructures were utilized to replicate a seed pattern that resulted in the growth of populations of nanostructures. Exponential growth could be controlled by environmental conditions depending on the preferential requirements of each population.

  19. Nanostructured materials in potentiometry.

    PubMed

    Düzgün, Ali; Zelada-Guillén, Gustavo A; Crespo, Gastón A; Macho, Santiago; Riu, Jordi; Rius, F Xavier

    2011-01-01

    Potentiometry is a very simple electrochemical technique with extraordinary analytical capabilities. It is also well known that nanostructured materials display properties which they do not show in the bulk phase. The combination of the two fields of potentiometry and nanomaterials is therefore a promising area of research and development. In this report, we explain the fundamentals of potentiometric devices that incorporate nanostructured materials and we highlight the advantages and drawbacks of combining nanomaterials and potentiometry. The paper provides an overview of the role of nanostructured materials in the two commonest potentiometric sensors: field-effect transistors and ion-selective electrodes. Additionally, we provide a few recent examples of new potentiometric sensors that are based on receptors immobilized directly onto the nanostructured material surface. Moreover, we summarize the use of potentiometry to analyze processes involving nanostructured materials and the prospects that the use of nanopores offer to potentiometry. Finally, we discuss several difficulties that currently hinder developments in the field and some future trends that will extend potentiometry into new analytical areas such as biology and medicine.

  20. IRAC Excess in Distant Star-Forming Galaxies: Tentative Evidence for the 3.3 μm Polycyclic Aromatic Hydrocarbon Feature?

    NASA Astrophysics Data System (ADS)

    Magnelli, B.; Chary, R. R.; Pope, A.; Elbaz, D.; Morrison, G.; Dickinson, M.

    2008-07-01

    We present evidence for the existence of an IRAC excess in the spectral energy distribution (SED) of five galaxies at 0.6 < z < 0.9 and one galaxy at z = 1.7. These six galaxies, located in the Great Observatories Origins Deep Survey field (GOODS-N), are star-forming since they present strong 6.2, 7.7, and, 11.3 μm polycyclic aromatic hydrocarbon (PAH) lines in their Spitzer IRS mid-infrared spectra. We use a library of templates computed with PEGASE.2 to fit their multiwavelength photometry and derive their stellar continuum. Subtraction of the stellar continuum enables us to detect in five galaxies a significant excess in the IRAC band pass where the 3.3 μm PAH is expected (i.e., IRAC 5.8 μm for the range of redshifts considered here). We then assess if the physical origin of the IRAC excess is due to an obscured active galactic nucleus (AGN) or warm dust emission. For one galaxy evidence of an obscured AGN is found, while the remaining four do not exhibit any significant AGN activity. Possible contamination by warm dust continuum of unknown origin as found in the Galactic diffuse emission is discussed. The properties of such a continuum would have to be different from the local universe to explain the measured IRAC excess, but we cannot definitively rule out this possibility until its origin is understood. Assuming that the IRAC excess is dominated by the 3.3 μm PAH feature, we find good agreement with the observed 11.3 μm PAH line flux arising from the same C-H bending and stretching modes, consistent with model expectations. Finally, the IRAC excess appears to be correlated with the star formation rate in the galaxies. Hence it could provide a powerful diagnostic for measuring dusty star formation in z > 3 galaxies once the mid-infrared spectroscopic capabilities of the James Webb Space Telescope become available.

  1. Closed form unsupervised registration of multi-temporal structure from motion-multiview stereo data using non-linearly weighted image features

    NASA Astrophysics Data System (ADS)

    Seers, T. D.; Hodgetts, D.

    2013-12-01

    Seers, T. D. & Hodgetts, D. School of Earth, Atmospheric and Environmental Sciences, University of Manchester, UK. M13 9PL. The detection of topological change at the Earth's surface is of considerable scholarly interest, allowing the quantification of the rates of geomorphic processes whilst providing lucid insights into the underlying mechanisms driving landscape evolution. In this regard, the past decade has witnessed the ever increasing proliferation of studies employing multi-temporal topographic data in within the geosciences, bolstered by continuing technical advancements in the acquisition and processing of prerequisite datasets. Provided by workers within the field of Computer Vision, multiview stereo (MVS) dense surface reconstructions, primed by structure-from-motion (SfM) based camera pose estimation represents one such development. Providing a cost effective, operationally efficient data capture medium, the modest requirement of a consumer grade camera for data collection coupled with the minimal user intervention required during post-processing makes SfM-MVS an attractive alternative to terrestrial laser scanners for collecting multi-temporal topographic datasets. However, in similitude to terrestrial scanner derived data, the co-registration of spatially coincident or partially overlapping scans produced by SfM-MVS presents a major technical challenge, particularly in the case of semi non-rigid scenes produced during topographic change detection studies. Moreover, the arbitrary scaling resulting from SfM ambiguity requires that a scale matrix must be estimated during the transformation, introducing further complexity into its formulation. Here, we present a novel, fully unsupervised algorithm which utilises non-linearly weighted image features for the solving the similarity transform (scale, translation rotation) between partially overlapping scans produced by SfM-MVS image processing. With the only initialization condition being partial intersection

  2. Nanostructured biointerfacing of metals with carbon nanotube/chitosan hybrids by electrodeposition for cell stimulation and therapeutics delivery.

    PubMed

    Patel, Kapil D; Kim, Tae-Hyun; Lee, Eun-Jung; Han, Cheol-Min; Lee, Ja-Yeon; Singh, Rajendra K; Kim, Hae-Won

    2014-11-26

    Exploring the biological interfaces of metallic implants has been an important issue in achieving biofunctional success. Here we develop a biointerface with nanotopological features and bioactive composition, comprising a carbon nanotube (CNT) and chitosan (Chi) hybrid, via an electrophoretic deposition (EPD). The physicochemical properties, in vitro biocompatibility, and protein delivering capacity of the decorated nanohybrid layer were investigated, to address its potential usefulness as bone regenerating implants. Over a wide compositional range, the nanostructured hybrid interfaces were successfully formed with varying thicknesses, depending on the electrodeposition parameters. CNT-Chi hybrid interfaces showed a time-sequenced degradation in saline water, and a rapid induction of hydroxyapatite mineral in a simulated body fluid. The nanostructured hybrid substrates stimulated the initial adhesion events of the osteoblastic cells, including cell adhesion rate, spreading behaviors, and expression of adhesive proteins. The nanostructured hybrid interfaces significantly improved the adsorption of protein molecules, which was enabled by the surface charge interaction, and increased surface area of the nanotopology. Furthermore, the incorporated protein was released at a highly sustained rate, profiling a diffusion-controlled pattern over a couple of weeks, suggesting the possible usefulness as a protein delivery device. Collectively, the nanostructured hybrid CNT-Chi layer, implemented by an electrodeposition, is considered a biocompatible, cell-stimulating, and protein-delivering biointerface of metallic implants.

  3. Controllable fabrication of copper phthalocyanine nanostructure crystals.

    PubMed

    Liu, Fangmei; Sun, Jia; Xiao, Si; Huang, Wenglong; Tao, Shaohua; Zhang, Yi; Gao, Yongli; Yang, Junliang

    2015-06-05

    Copper phthalocyanine (CuPc) nanostructure crystals, including nanoflower, nanoribbon, and nanowire, were controllably fabricated by temperature gradient physical vapor deposition (TG-PVD) through controlling the growth parameters. In a controllable growth system with carrier gas N2, nanoflower, nanoribbon, and nanowire crystals were formed in a high-temperature zone, medium-temperature zone, and low-temperature zone, respectively. They were proved to be β-phase, coexist of α-phase and β-phase, and α-phase respectively based on x-ray diffraction results. Furthermore, ultralong CuPc nanowires up to several millimeters could be fabricated by TG-PVD without carrier gas, and they were well-aligned to form large-area CuPc nanowire crystal arrays by the Langmuir-Blodgett method. The nanostructure crystals showed unusual optical absorption spectra from the ultraviolet-visible to near-infrared range, which was explained by the diffraction and scattering caused by the wavelength-sized nanostructures. These CuPc nanostructure crystals show potential applications in organic electronic and optoelectronic devices.

  4. Controllable synthesis of conducting polypyrrole nanostructures.

    PubMed

    Zhang, Xuetong; Zhang, Jin; Song, Wenhui; Liu, Zhongfan

    2006-01-26

    Wire-, ribbon-, and sphere-like nanostructures of polypyrrole have been synthesized by solution chemistry methods in the presence of various surfactants (anionic, cationic, or nonionic surfactant) with various oxidizing agents [ammonium persulfate (APS) or ferric chloride (FeCl3), respectively]. The surfactants and oxidizing agents used in this study have played a key role in tailoring the nanostructures of polypyrrole during the polymerization. It is inferred that the lamellar structures of a mesophase are formed by self-assembly between the cations of a long chain cationic surfactant [cetyltrimethylammonium bromide (CTAB) or dodeyltrimethylammonium bromide (DTAB)] and anions of oxidizing agent APS. These layered mesostructures are presumed to act as templates for the formation of wire- and ribbon-like polypyrrole nanostructures. In contrast, if a short chain cationic surfactant octyltrimethylammonium bromide (OTAB) or nonionic surfactant poly(ethylene glycol) mono-p-nonylphenyl ether (Opi-10) is used, sphere-like polypyrrole nanostructures are obtained, whichever of the oxidizing agents mentioned above is used. In this case, micelles resulting from self-assembly among surfactant molecules are envisaged to serve as the templates while the polymerization happens. It is also noted that, if anionic surfactant sodium dodeyl surfate (SDS) is used, no characteristic nanostructures of polypyrrole were observed. This may be attributed to the doping effect of anionic surfactants into the resulting polypyrrole chains, and as a result, micelles self-assembled among surfactant molecules are broken down during the polymerization. The effects of monomer concentration, surfactant concentration, and surfactant chain length on the morphologies of the resulting polypyrrole have been investigated in detail. The molecular structures, composition, and electrical properties of the nanostructured polypyrrole have also been investigated in this study.

  5. Hydrothermal synthetic strategies of inorganic semiconducting nanostructures.

    PubMed

    Shi, Weidong; Song, Shuyan; Zhang, Hongjie

    2013-07-07

    Because of their unique chemical and physical properties, inorganic semiconducting nanostructures have gradually played a pivotal role in a variety of research fields, including electronics, chemical reactivity, energy conversion, and optics. A major feature of these nanostructures is the quantum confinement effect, which strongly depends on their size, shape, crystal structure and polydispersity. Among all developed synthetic methods, the hydrothermal method based on a water system has attracted more and more attention because of its outstanding advantages, such as high yield, simple manipulation, easy control, uniform products, lower air pollution, low energy consumption and so on. Precise control over the hydrothermal synthetic conditions is a key to the success of the preparation of high-quality inorganic semiconducting nanostructures. In this review, only the representative hydrothermal synthetic strategies of inorganic semiconducting nanostructures are selected and discussed. We will introduce the four types of strategies based on exterior reaction system adjustment, namely organic additive- and template-free hydrothermal synthesis, organic additive-assisted hydrothermal synthesis, template-assisted hydrothermal synthesis and substrate-assisted hydrothermal synthesis. In addition, the two strategies based on exterior reaction environment adjustment, including microwave-assisted and magnetic field-assisted hydrothermal synthesis, will be also described. Finally, we conclude and give the future prospects of this research area.

  6. Tailoring the shape of oxide complex nanostructures

    NASA Astrophysics Data System (ADS)

    Méndez, B.; López, I.; Alonso-Orts, M.; Sanz, A.; Nogales, E.; Hidalgo, P.; Piqueras, J.

    2017-05-01

    The synthesis of complex nanostructures that combine materials and dimensionality, promises the ability to identify novel designs and architectures with enhanced properties that could be used in new devices. One of the building blocks in nanomaterials are nanowires, which offer several possibilities to get complex nanostructures. We present two kinds of morphologies based on oxide nanowires obtained by a thermal evaporation method. The common feature of both morphologies is a central oxide nanowire and, depending on the growth parameters, nanowires with either nanocrystallites or nano/microrods attached to the central wire are obtained. We have previously reported the fabrication of several single oxide nanowires and in particular, gallium oxide (β-Ga2O3) and zinc germanate oxide (Zn2GeO4) nanowires. Here we report the shape evolution of these nanowires by the suitable modification of the growth parameters. The addition of tin oxide (SnO2) to the precursors and variation of the thermal treatments duration result in the formation of the above-mentioned complex nanostructures. Structural and chemical characterizations were performed by electron microscopy techniques and Raman spectroscopy. The results shed light on the understanding of the driving mechanisms that lead to the formation of complex oxide nanostructures.

  7. Process for the preparation of metal-containing nanostructured films

    NASA Technical Reports Server (NTRS)

    Lu, Yunfeng (Inventor); Wang, Donghai (Inventor)

    2006-01-01

    Metal-containing nanostructured films are prepared by electrodepositing a metal-containing composition within the pores of a mesoporous silica template to form a metal-containing silica nanocomposite. The nanocomposite is annealed to strengthen the deposited metal-containing composition. The silica is then removed from the nanocomposite, e.g., by dissolving the silica in an etching solution to provide a self-supporting metal-containing nanostructured film. The nanostructured films have a nanowire or nanomesh architecture depending on the pore structure of the mesoporous silica template used to prepare the films.

  8. Geometrically induced surface polaritons in planar nanostructured metallic cavities

    SciTech Connect

    Davids, P. S.; Intravia, F; Dalvit, Diego A.

    2014-01-14

    We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer at short separations.

  9. Characterization of Si nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Zaidi, Saleem H.; Gee, James M.; Ruby, Douglas S.; Brueck, Steven R. J.

    1999-06-01

    Surface scattering of Si to enhanced absorption particularly in the IR spectral region has been extensively investigated. Previous research chiefly examined approaches based on geometrical optics. These surface textures typically consist of pyramids with dimensions much larger than optical wavelengths. We have investigated a physical optics approach that relies on surface texture features comparable to, or smaller than, the optical wavelengths inside the semiconductor material. Light interaction at this are strongly dependent on incident polarization and surface profile. Nanoscale textures can be tuned for either narrow band, or broad band absorptive behavior. Lowest broad band reflection has been observed for triangular profiles with linewidths significantly less than 100 nm. Si nanostructures have been integrated into large (approximately 42 cm2) area solar cells. Internal quantum efficiency measurements in comparison with polished and conventionally textured cells show lower efficiency in the UV-visible (350 - 680 nm), but significantly higher IR (700 - 1200 nm) efficiency.

  10. Characterization of Si Nanostructured Surfaces

    SciTech Connect

    Brueck, S.R.J.; Gee, James M.; Ruby, Douglas S.; Zaidi, Saleem H.

    1999-07-20

    Surface texturing of Si to enhance absorption particularly in the IR spectral region has been extensively investigated. Previous research chiefly examined approaches based on geometrical optics. These surface textures typically consist of pyramids with dimensions much larger than optical wavelengths. We have investigated a physical optics approach that relies on surface texture features comparable to, or smaller than, the optical wavelengths inside the semiconductor material. Light interaction at this are strongly dependent on incident polarization and surface profile. Nanoscale textures can be tuned for either narrow band, or broad band absorptive behavior. Lowest broadband reflection has been observed for triangular profiles with linewidths significantly less than 100 nm. Si nanostructures have been integrated into large ({approximately}42 cm{sup 2}) area solar cells, Internal quantum efficiency measurements in comparison with polished and conventionally textured cells show lower efficiency in the UV-visible (350-680 mu), but significantly higher IR (700-1200 nm) efficiency.

  11. Fabrication of Ordered Blue Nanostructure by Anodization of an Aluminum Plate

    NASA Astrophysics Data System (ADS)

    Kurashima, Yuichi; Yokota, Yoshihiko; Miyamoto, Iwao; Itatani, Taro

    2007-03-01

    Colors in organisms are created by chemical interactions of molecular pigments and by optical interactions of incident light with biological nanostructures. The latter classes are called structural colors and form an important component of the phenotypes of many animals and even some plants. In this paper, we report on the fabrication of an ordered blue nanostructure by the anodization of an Al plate. In the fabrication of such an ordered nanostructure by the anodization of an Al plate, ordered nanostructures with a pitch and an alumina thickness of approximately 100 nm were produced on the Al plate. The ordered nanostructures on the Al plate showed no colors. However, an ordered nanostructure deposited with a Pt thin film with a thickness of approximately 10 nm showed a blue reflection with a peak reflectivity of approximately 370 nm. We conclude that this blue nanostructure on the Al plate is caused by an interference between the Al surface and the Pt surface.

  12. PSNO: predicting cysteine S-nitrosylation sites by incorporating various sequence-derived features into the general form of Chou's PseAAC.

    PubMed

    Zhang, Jian; Zhao, Xiaowei; Sun, Pingping; Ma, Zhiqiang

    2014-06-25

    S-nitrosylation (SNO) is one of the most universal reversible post-translational modifications involved in many biological processes. Malfunction or dysregulation of SNO leads to a series of severe diseases, such as developmental abnormalities and various diseases. Therefore, the identification of SNO sites (SNOs) provides insights into disease progression and drug development. In this paper, a new bioinformatics tool, named PSNO, is proposed to identify SNOs from protein sequences. Firstly, we explore various promising sequence-derived discriminative features, including the evolutionary profile, the predicted secondary structure and the physicochemical properties. Secondly, rather than simply combining the features, which may bring about information redundancy and unwanted noise, we use the relative entropy selection and incremental feature selection approach to select the optimal feature subsets. Thirdly, we train our model by the technique of the k-nearest neighbor algorithm. Using both informative features and an elaborate feature selection scheme, our method, PSNO, achieves good prediction performance with a mean Mathews correlation coefficient (MCC) value of about 0.5119 on the training dataset using 10-fold cross-validation. These results indicate that PSNO can be used as a competitive predictor among the state-of-the-art SNOs prediction tools. A web-server, named PSNO, which implements the proposed method, is freely available at http://59.73.198.144:8088/PSNO/.

  13. Nanostructured materials for hydrogen storage

    DOEpatents

    Williamson, Andrew J.; Reboredo, Fernando A.

    2007-12-04

    A system for hydrogen storage comprising a porous nano-structured material with hydrogen absorbed on the surfaces of the porous nano-structured material. The system of hydrogen storage comprises absorbing hydrogen on the surfaces of a porous nano-structured semiconductor material.

  14. Nanostructured Biomaterials for Regeneration**

    PubMed Central

    Wei, Guobao; Ma, Peter X.

    2009-01-01

    Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/dysfunctional tissues or organs. Biomaterials (scaffolds) serve as temporary 3D substrates to guide neo tissue formation and organization. It is often beneficial for a scaffolding material to mimic the characteristics of extracellular matrix (ECM) at the nanometer scale and to induce certain natural developmental or/and wound healing processes for tissue regeneration applications. This article reviews the fabrication and modification technologies for nanofibrous, nanocomposite, and nanostructured drug-delivering scaffolds. ECM-mimicking nanostructured biomaterials have been shown to actively regulate cellular responses including attachment, proliferation, differentiation and matrix deposition. Nano-scaled drug delivery systems can be successfully incorporated into a porous 3D scaffold to enhance the tissue regeneration capacity. In conclusion, nano-structured biomateials are a very exciting and rapidly expanding research area, and are providing new enabling technologies for regenerative medicine. PMID:19946357

  15. Synthesis of porphyrin nanostructures

    DOEpatents

    Fan, Hongyou; Bai, Feng

    2014-10-28

    The present disclosure generally relates to self-assembly methods for generating porphyrin nanostructures. For example, in one embodiment a method is provided that includes preparing a porphyrin solution and a surfactant solution. The porphyrin solution is then mixed with the surfactant solution at a concentration sufficient for confinement of the porphyrin molecules by the surfactant molecules. In some embodiments, the concentration of the surfactant is at or above its critical micelle concentration (CMC), which allows the surfactant to template the growth of the nanostructure over time. The size and morphology of the nanostructures may be affected by the type of porphyrin molecules used, the type of surfactant used, the concentration of the porphyrin and surfactant the pH of the mixture of the solutions, and the order of adding the reagents to the mixture, to name a few variables.

  16. Experiment-Driven Modeling of Plasmonic Nanostructures

    NASA Astrophysics Data System (ADS)

    Hryn, Alexander John

    Plasmonic nanostructures can confine light at their surface in the form of surface plasmon polaritons (SPPs) or localized surface plasmons (LSPs) depending on their geometry. SPPs are excited on nano- and micropatterned surfaces, where the typical feature size is on the order of the wavelength of light. LSPs, on the other hand, can be excited on nanoparticles much smaller than the diffraction limit. In both cases, far-field optical measurements are used to infer the excited plasmonic modes, and theoretical models are used to verify those results. Typically, these theoretical models are tailored to match the experimental nanostructures in order to explain observed phenomena. In this thesis, I explore incorporating components of experimental procedures into the models to increase the accuracy of the simulated result, and to inform the design of future experiments. First, I examine SPPs on nanostructured metal films in the form of low-symmetry moire plasmonic crystals. I created a general Bragg model to understand and predict the excited SPP modes in moire plasmonic crystals based on the nanolithography masks used in their fabrication. This model makes use of experimental parameters such as periodicity, azimuthal rotation, and number of sequential exposures to predict the energies of excited SPP modes and the opening of plasmonic band gaps. The model is further expanded to apply to multiscale gratings, which have patterns that contain hierarchical periodicities: a sub-micron primary periodicity, and microscale superperiodicity. A new set of rules was established to determine how superlattice SPPs are excited, and informed development of a new fabrication technique to create superlattices with multiple primary periodicities that absorb light over a wider spectral range than other plasmonic structures. The second half of the thesis is based on development of finite-difference time-domain (FDTD) simulations of plasmonic nanoparticles. I created a new technique to model

  17. Three-dimensional hierarchical Te-Si nanostructures.

    PubMed

    Lim, Jae-Hong; Shin, Gyeong-Jin; Hwang, Tae-Yeon; Lim, Hyo-Ryoung; Lee, Young-In; Lee, Kyu-Hwan; Kim, Sung-Dae; Oh, Min-Wook; Park, Su-Dong; Myung, Nosang V; Choa, Yong-Ho

    2014-10-21

    Three-dimensional hybrid nanostructures (i.e., Te "nanobranches" on a Si "nanotrunk" or Te "nanoleaves" on a Si "nanotrunk") were synthesized by combining the gold-assisted chemical etching of Si to form Si "nanotrunks" and the galvanic displacement of Si to form Te "nanobranches" or "nanoleaves." By adjusting the composition of the electrolyte used for the galvanic displacement reaction, the shape of the Te nanostructures could be changed from nanoleaves to nanobranches. The Si nanotrunks with Te nanobranches showed stronger luminescent emission in the visible region, with their Raman spectrum having a higher wave number, owing to their grain size being larger. This suggested that the optical and photoelectrochemical properties of Te-Si hybrid nanostructures depend on their shape and size. Using this approach, it should be possible to fabricate various hierarchical nanostructures for use in photoelectronic and photoelectrochemical devices.

  18. Chiral Inorganic Nanostructures.

    PubMed

    Ma, Wei; Xu, Liguang; de Moura, André F; Wu, Xiaoling; Kuang, Hua; Xu, Chuanlai; Kotov, Nicholas A

    2017-06-28

    The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of individual nanoparticles (NPs) and their assemblies and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others. Multiple chiral geometries were observed with characteristic scales from ångströms to microns. Uniquely high values of chiral anisotropy factors that spurred the development of the field and differentiate it from chiral structures studied before, are now well understood; they originate from strong resonances of incident electromagnetic waves with plasmonic and excitonic states typical for metals and semiconductors. At the same time, distinct similarities with chiral supramolecular and biological systems also emerged. They can be seen in the synthesis and separation methods, chemical properties of individual NPs, geometries of the nanoparticle assemblies, and interactions with biological membranes. Their analysis can help us understand in greater depth the role of chiral asymmetry in nature inclusive of both earth and space. Consideration of both differences and similarities between chiral inorganic, organic, and biological nanostructures will also accelerate the development of technologies based on chiroplasmonic and chiroexcitonic effects. This review will cover both experiment and theory of chiral nanostructures starting with the origin and multiple components of mirror asymmetry of individual NPs and their assemblies. We shall consider four different types of chirality in nanostructures and related physical, chemical, and

  19. Templated Self Assemble of Nano-Structures

    SciTech Connect

    Suo, Zhigang

    2013-04-29

    This project will identify and model mechanisms that template the self-assembly of nanostructures. We focus on a class of systems involving a two-phase monolayer of molecules adsorbed on a solid surface. At a suitably elevated temperature, the molecules diffuse on the surface to reduce the combined free energy of mixing, phase boundary, elastic field, and electrostatic field. With no template, the phases may form a pattern of stripes or disks. The feature size is on the order of 1-100 nm, selected to compromise the phase boundary energy and the long-range elastic or electrostatic interaction. Both experimental observations and our theoretical simulations have shown that the pattern resembles a periodic lattice, but has abundant imperfections. To form a perfect periodic pattern, or a designed aperiodic pattern, one must introduce a template to guide the assembly. For example, a coarse-scale pattern, lithographically defined on the substrate, will guide the assembly of the nanoscale pattern. As another example, if the molecules on the substrate surface carry strong electric dipoles, a charged object, placed in the space above the monolayer, will guide the assembly of the molecular dipoles. In particular, the charged object can be a mask with a designed nanoscale topographic pattern. A serial process (e.g., e-beam lithography) is necessary to make the mask, but the pattern transfer to the molecules on the substrate is a parallel process. The technique is potentially a high throughput, low cost process to pattern a monolayer. The monolayer pattern itself may serve as a template to fabricate a functional structure. This project will model fundamental aspects of these processes, including thermodynamics and kinetics of self-assembly, templated self-assembly, and self-assembly on unconventional substrates. It is envisioned that the theory will not only explain the available experimental observations, but also motivate new experiments.

  20. Nanostructured Solar Cells

    PubMed Central

    Chen, Guanying; Ning, Zhijun; Ågren, Hans

    2016-01-01

    We are glad to announce the Special Issue “Nanostructured Solar Cells”, published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  1. Plasmonics in nanostructures.

    PubMed

    Fang, Zheyu; Zhu, Xing

    2013-07-26

    Plasmonics has developed into one of the rapidly growing research topics for nanophotonics. With advanced nanofabrication techniques, a broad variety of nanostructures can be designed and fabricated for plasmonic devices at nanoscale. Fundamental properties for both surface plasmon polaritons (SPP) and localized surface plasmons (LSP) arise a new insight and understanding for the electro-optical device investigations, such as plasmonic nanofocusing, low-loss plasmon waveguide and active plasmonic detectors for energy harvesting. Here, we review some typical functional plasmonic nanostructures and nanosmart devices emerging from our individual and collaborative research works. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Nanostructured Solar Cells.

    PubMed

    Chen, Guanying; Ning, Zhijun; Ågren, Hans

    2016-08-09

    We are glad to announce the Special Issue "Nanostructured Solar Cells", published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  3. Simulation of Semiconductor Nanostructures

    SciTech Connect

    Williamson, A J; Grossman, J C; Puzder, A; Benedict, L X; Galli, G

    2001-07-19

    The field of research into the optical properties of silicon nanostructures has seen enormous growth over the last decade. The discovery that silicon nanoparticles exhibit visible photoluminescence (PL) has led to new insights into the mechanisms responsible for such phenomena. The importance of understanding and controlling the PL properties of any silicon based material is of paramount interest to the optoelectronics industry where silicon nanoclusters could be embedded into existing silicon based circuitry. In this talk, we present a combination of quantum Monte Carlo and density functional approaches to the calculation of the electronic, structural, and optical properties of silicon nanostructures.

  4. Ultrasensitive electrochemical cocaine biosensor based on reversible DNA nanostructure.

    PubMed

    Sheng, Qinglin; Liu, Ruixiao; Zhang, Sai; Zheng, Jianbin

    2014-01-15

    We proposed an ultrasensitive electrochemical cocaine biosensor based on the three-dimensional (3D) DNA structure conversion of nanostructure from Triangular Pyramid Frustum (TPFDNA) to Equilateral Triangle (ETDNA). The presence of cocaine triggered the aptamer-composed DNA nanostructure change from "Close" to "Open", leading to obvious faradaic impedance changes. The unique properties with excellent stability and specific rigid structure of the 3D DNA nanostructure made the biosensing functions stable, sensitive, and regenerable. The Faradaic impedance responses were linearly related to cocaine concentration between 1.0 nM and 2.0 μM with a correlation coefficient of 0.993. The limit of detection was calculated to be 0.21 nM following IUPAC recommendations (3Sb/b). It is expected that the distinctive features of DNA nanostructure would make it potentially advantageous for a broad range of biosensing, bionanoelectronics, and therapeutic applications.

  5. Metamaterial 3D Gain Nanostructures Fabricated Using Direct Laser Writing

    DTIC Science & Technology

    2015-07-11

    AFRL-AFOSR-UK-TR-2015-0033 Metamaterial 3D Gain Nanostructures Fabricated Using Direct Laser Writing Maria Farsari...abricated Direct Laser Writing 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA8655-13-1-3048 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Maria Farsari 5d...Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39-18   1 Metamaterial 3D Gain Nanostructures Fabricated Using Direct Laser Writing EOARD

  6. Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

    SciTech Connect

    Wójcik, P. Adamowski, J. Wołoszyn, M.; Spisak, B. J.

    2015-07-07

    We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be used to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.

  7. Controlled formation of nanostructures on MoS2 layers by focused laser irradiation

    NASA Astrophysics Data System (ADS)

    Rani, Renu; Dimple, Jena, Nityasagar; Kundu, Anirban; Sarkar, Abir De; Hazra, Kiran Shankar

    2017-02-01

    MoS2 nanostructures, i.e., nanoribbons, nano-mesh, etc., may open different prospect of applications in nano-electronic and opto-electronic devices and sensors. However, the fabrication of these complicated nanostructures can be executed by using standard nano-patterning techniques such as lithography, printing, etc. Nevertheless, these standard techniques involve affluent multistep processes to optimize scalability, form factors and accuracy in the feature size. Herein, we demonstrate the fabrication of unique nano-structures on MoS2, such as nano-ribbons and nano-mesh, by a simple one-step process of direct laser writing using 532 nm low power focused laser. The minimum power required to etch a MoS2 layer for a 532 nm laser is found to be ˜6.95 mW and the minimum void size observed is ˜300 nm, which is very close to the diffraction limit of the laser used. Both the experimental and computational results have shown that the voids induced by laser etching always take a hexagonal or triangular shape, which can be used to define crystal orientation of the MoS2 flake. Investigation shows that the periphery of hexagonal voids lies on S atoms, whereas for triangular voids, it lies on Mo atoms of the MoS2 crystal. In-depth AFM and Raman analysis show that the etching rate is tunable by controlling the laser power and the exposure time.

  8. STM observation of a box-shaped graphene nanostructure appeared after mechanical cleavage of pyrolytic graphite

    NASA Astrophysics Data System (ADS)

    Lapshin, Rostislav V.

    2016-01-01

    A description is given of a three-dimensional box-shaped graphene (BSG) nanostructure formed/uncovered by mechanical cleavage of highly oriented pyrolytic graphite (HOPG). The discovered nanostructure is a multilayer system of parallel hollow channels located along the surface and having quadrangular cross-section. The thickness of the channel walls/facets is approximately equal to 1 nm. The typical width of channel facets makes about 25 nm, the channel length is 390 nm and more. The investigation of the found nanostructure by means of a scanning tunneling microscope (STM) allows us to draw a conclusion that it is possible to make spatial constructions of graphene similar to the discovered one by mechanical compression, bending, splitting, and shifting graphite surface layers. The distinctive features of such constructions are the following: simplicity of the preparation method, small contact area between graphene planes and a substrate, large surface area, nanometer cross-sectional sizes of the channels, large aspect ratio. Potential fields of application include: ultra-sensitive detectors, high-performance catalytic cells, nanochannels for DNA manipulation, nanomechanical resonators, electron multiplication channels, high-capacity sorbents for hydrogen storage.

  9. Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

    NASA Astrophysics Data System (ADS)

    Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

    2015-07-01

    We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be used to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.

  10. Nanostructured luminescently labeled nucleic acids.

    PubMed

    Kricka, Larry J; Fortina, Paolo; Park, Jason Y

    2017-03-01

    Important and emerging trends at the interface of luminescence, nucleic acids and nanotechnology are: (i) the conventional luminescence labeling of nucleic acid nanostructures (e.g. DNA tetrahedron); (ii) the labeling of bulk nucleic acids (e.g. single-stranded DNA, double-stranded DNA) with nanostructured luminescent labels (e.g. copper nanoclusters); and (iii) the labeling of nucleic acid nanostructures (e.g. origami DNA) with nanostructured luminescent labels (e.g. silver nanoclusters). This review surveys recent advances in these three different approaches to the generation of nanostructured luminescently labeled nucleic acids, and includes both direct and indirect labeling methods. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Fabrication and characterization of carbon doped molybdenum oxide nanostructures.

    PubMed

    Wisitsoraat, A; Tuantranont, A; Patthanasettakul, V; Lomas, T

    2009-02-01

    Molybdenum oxide (MoOx) nanostructure has gained considerable attention because of its low-cost fabrication by low-temperature evaporation/condensation technique and its promising properties for applications in the field of catalysts and chemical sensors. However, MoOx has some inferior properties including very high electrical resistivity and instability at elevated temperature. These properties may be improved by means of foreign atom addition into its nanostructure. In this work, we develop a simple mean for doping of MoOx nanostructures by introduction of gas source dopant during evaporation. Carbon doped MoOx nanostructures have been synthesized by MoOx powder evaporation in Argon/Acetylene mixture with varying process parameters. Depending on growth conditions, various nanostructures including, nanorod, nanoplate, nanodots, can be formed with different dimensions and doping concentrations. Structural characterization by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) indicate that the MoOx based nanostructures are highly crystalline and carbon dopant is successfully incorporated in the structure with controllable concentration. Electrical characterization shows that the electrical conductivity of molybdenum oxide nanostructures can be increased by several orders of magnitude with carbon incorporation.

  12. Metal oxide nanostructures by a simple hot water treatment.

    PubMed

    Saadi, Nawzat S; Hassan, Laylan B; Karabacak, Tansel

    2017-08-02

    Surfaces with metal oxide nanostructures have gained considerable interest in applications such as sensors, detectors, energy harvesting cells, and batteries. However, conventional fabrication techniques suffer from challenges that hinder wide and effective applications of such surfaces. Most of the metal oxide nanostructure synthesis methods are costly, complicated, non-scalable, environmentally hazardous, or applicable to only certain few materials. Therefore, it is crucial to develop a simple metal oxide nanostructure fabrication method that can overcome all these limitations and pave the way to the industrial application of such surfaces. Here, we demonstrate that a wide variety of metals can form metal oxide nanostructures on their surfaces after simply interacting with hot water. This method, what we call hot water treatment, offers the ability to grow metal oxide nanostructures on most of the metals in the periodic table, their compounds, or alloys by a one-step, scalable, low-cost, and eco-friendly process. In addition, our findings reveal that a "plugging" mechanism along with surface diffusion is critical in the formation of such nanostructures. This work is believed to be of importance especially for researchers working on the growth of metal oxide nanostructures and their application in functional devices.

  13. Nanostructured catalyst supports

    DOEpatents

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2012-10-02

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  14. Nanostructured catalyst supports

    DOEpatents

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2015-09-29

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  15. Building Nanostructures with Drugs

    PubMed Central

    Ma, Wang; Cheetham, Andrew G.

    2016-01-01

    The convergence of nanoscience and drug delivery has prompted the formation of the field of nanomedicine, one that exploits the novel physicochemical and biological properties of nanostructures for improved medical treatments and reduced side effects. Until recently, this nanostructure-mediated strategy considered the drug to be solely a biologically active compound to be delivered, and its potential as a molecular building unit remained largely unexplored. A growing trend within nanomedicine has been the use of drug molecules to build well-defined nanostructures of various sizes and shapes. This strategy allows for the creation of self-delivering supramolecular nanomedicines containing a high and fixed drug content. Through rational design of the number and type of the drug incorporated, the resulting nanostructures can be tailored to assume various morphologies (e.g. nanospheres, rods, nanofibers, or nanotubes) for a particular mode of administration such as systemic, topical, and local delivery. This review covers the recent advances in this rapidly developing field, with the aim of providing an in-depth evaluation of the exciting opportunities that this new field could create to improve the current clinical practice of nanomedicine. PMID:27066106

  16. Emerging double helical nanostructures

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    As one of the most important and land-mark structures found in nature, a double helix consists of two congruent single helices with the same axis or a translation along the axis. This double helical structure renders the deoxyribonucleic acid (DNA) the crucial biomolecule in evolution and metabolism. DNA-like double helical nanostructures are probably the most fantastic yet ubiquitous geometry at the nanoscale level, which are expected to exhibit exceptional and even rather different properties due to the unique organization of the two single helices and their synergistic effect. The organization of nanomaterials into double helical structures is an emerging hot topic for nanomaterials science due to their promising exceptional unique properties and applications. This review focuses on the state-of-the-art research progress for the fabrication of double-helical nanostructures based on `bottom-up' and `top-down' strategies. The relevant nanoscale, mesoscale, and macroscopic scale fabrication methods, as well as the properties of the double helical nanostructures are included. Critical perspectives are devoted to the synthesis principles and potential applications in this emerging research area. A multidisciplinary approach from the scope of nanoscience, physics, chemistry, materials, engineering, and other application areas is still required to the well-controlled and large-scale synthesis, mechanism, property, and application exploration of double helical nanostructures.

  17. Emerging double helical nanostructures.

    PubMed

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

    2014-08-21

    As one of the most important and land-mark structures found in nature, a double helix consists of two congruent single helices with the same axis or a translation along the axis. This double helical structure renders the deoxyribonucleic acid (DNA) the crucial biomolecule in evolution and metabolism. DNA-like double helical nanostructures are probably the most fantastic yet ubiquitous geometry at the nanoscale level, which are expected to exhibit exceptional and even rather different properties due to the unique organization of the two single helices and their synergistic effect. The organization of nanomaterials into double helical structures is an emerging hot topic for nanomaterials science due to their promising exceptional unique properties and applications. This review focuses on the state-of-the-art research progress for the fabrication of double-helical nanostructures based on 'bottom-up' and 'top-down' strategies. The relevant nanoscale, mesoscale, and macroscopic scale fabrication methods, as well as the properties of the double helical nanostructures are included. Critical perspectives are devoted to the synthesis principles and potential applications in this emerging research area. A multidisciplinary approach from the scope of nanoscience, physics, chemistry, materials, engineering, and other application areas is still required to the well-controlled and large-scale synthesis, mechanism, property, and application exploration of double helical nanostructures.

  18. Harnessing microtubule dynamic instability for nanostructure assembly

    NASA Astrophysics Data System (ADS)

    Bouchard, Ann M.; Warrender, Christina E.; Osbourn, Gordon C.

    2006-10-01

    Intracellular molecular machines synthesize molecules, tear apart others, transport materials, transform energy into different forms, and carry out a host of other coordinated processes. Many molecular processes have been shown to work outside of cells, and the idea of harnessing these molecular machines to build nanostructures is attractive. Two examples are microtubules and motor proteins, which aid cell movement, help determine cell shape and internal structure, and transport vesicles and organelles within the cell. These molecular machines work in a stochastic, noisy fashion: microtubules switch randomly between growing and shrinking in a process known as dynamic instability; motor protein movement along microtubules is randomly interrupted by the motor proteins falling off. A common strategy in attempting to gain control over these highly dynamic, stochastic processes is to eliminate some processes (e.g., work with stabilized microtubules) in order to focus on others (interaction of microtubules with motor proteins). In this paper, we illustrate a different strategy for building nanostructures, which, rather than attempting to control or eliminate some dynamic processes, uses them to advantage in building nanostructures. Specifically, using stochastic agent-based simulations, we show how the natural dynamic instability of microtubules can be harnessed in building nanostructures, and discuss strategies for ensuring that “unreliable” stochastic processes yield a robust outcome.

  19. Harnessing microtubule dynamic instability for nanostructure assembly.

    SciTech Connect

    Bouchard, Ann Marie; Osbourn, Gordon Cecil

    2004-06-01

    Intracellular molecular machines synthesize molecules, tear apart others, transport materials, transform energy into different forms, and carry out a host of other coordinated processes. Many molecular processes have been shown to work outside of cells, and the idea of harnessing these molecular machines to build nanostructures is attractive. Two examples are microtubules and motor proteins, which aid cell movement, help determine cell shape and internal structure, and transport vesicles and organelles within the cell. These molecular machines work in a stochastic, noisy fashion: microtubules switch randomly between growing and shrinking in a process known as dynamic instability; motor protein movement along microtubules is randomly interrupted by the motor proteins falling off. A common strategy in attempting to gain control over these highly dynamic, stochastic processes is to eliminate some processes (e.g., work with stabilized microtubules) in order to focus on others (interaction of microtubules with motor proteins). In this paper, we illustrate a different strategy for building nanostructures, which, rather than attempting to control or eliminate some dynamic processes, uses them to advantage in building nanostructures. Specifically, using stochastic agent-based simulations, we show how the natural dynamic instability of microtubules can be harnessed in building nanostructures, and discuss strategies for ensuring that 'unreliable' stochastic processes yield a robust outcome.

  20. Nanostructured polyurethane-poly-lactic-co-glycolic acid scaffolds increase bladder tissue regeneration: an in vivo study.

    PubMed

    Yao, Chang; Hedrick, Matt; Pareek, Gyan; Renzulli, Joseph; Haleblian, George; Webster, Thomas J

    2013-01-01

    Although showing much promise for numerous tissue engineering applications, polyurethane and poly-lactic-co-glycolic acid (PLGA) have suffered from a lack of cytocompatibility, sometimes leading to poor tissue integration. Nanotechnology (or the use of materials with surface features or constituent dimensions less than 100 nm in at least one direction) has started to transform currently implanted materials (such as polyurethane and PLGA) to promote tissue regeneration. This is because nanostructured surface features can be used to change medical device surface energy to alter initial protein adsorption events important for promoting tissue-forming cell functions. Thus, due to their altered surface energetics, the objective of the present in vivo study was to create nanoscale surface features on a new polyurethane and PLGA composite scaffold (by soaking the polyurethane side and PLGA side in HNO₃ and NaOH, respectively) and determine bladder tissue regeneration using a minipig model. The novel nanostructured scaffolds were further functionalized with IKVAV and YIGSR peptides to improve cellular responses. Results provided the first evidence of increased in vivo bladder tissue regeneration when using a composite of nanostructured polyurethane and PLGA compared with control ileal segments. Due to additional surgery, extended potentially problematic healing times, metabolic complications, donor site morbidity, and sometimes limited availability, ileal segment repair of a bladder defect is not optimal and, thus, a synthetic analog is highly desirable. In summary, this study indicates significant promise for the use of nanostructured polyurethane and PLGA composites to increase bladder tissue repair for a wide range of regenerative medicine applications, such as regenerating bladder tissue after removal of cancerous tissue, disease, or other trauma.

  1. Synthesis and characterization of hybrid nanostructures

    PubMed Central

    Mokari, Taleb

    2011-01-01

    There has been significant interest in the development of multicomponent nanocrystals formed by the assembly of two or more different materials with control over size, shape, composition, and spatial orientation. In particular, the selective growth of metals on the tips of semiconductor nanorods and wires can act to couple the electrical and optical properties of semiconductors with the unique properties of various metals. Here, we outline our progress on the solution-phase synthesis of metal-semiconductor heterojunctions formed by the growth of Au, Pt, or other binary catalytic metal systems on metal (Cd, Pb, Cu)-chalcogenide nanostructures. We show the ability to grow the metal on various shapes (spherical, rods, hexagonal prisms, and wires). Furthermore, manipulating the composition of the metal nanoparticles is also shown, where PtNi and PtCo alloys are our main focus. The magnetic and electrical properties of the developed hybrid nanostructures are shown. PMID:22110873

  2. Dynamic Defrosting on Nanostructured Superhydrophobic Surfaces

    SciTech Connect

    Boreyko, Jonathan B.; Srijanto, Bernadeta R.; Nguyen, Trung Dac; Vega, Carlos; Fuentes-Cabrera, Miguel; Collier, C. Patrick

    2013-07-03

    Water suspended on chilled superhydrophobic surfaces exhibits delayed freezing; however, the interdrop growth of frost through subcooled condensate forming on the surface seems unavoidable in humid environments. It is therefore of great practical importance to determine whether facile defrosting is possible on superhydrophobic surfaces. Here in this paper, we report that nanostructured superhydrophobic surfaces promote the growth of frost in a suspended Cassie state, enabling its dynamic removal upon partial melting at low tilt angles (<15°). The dynamic removal of the melting frost occurred in two stages: spontaneous dewetting followed by gravitational mobilization. This dynamic defrosting phenomenon is driven by the low contact angle hysteresis of the defrosted meltwater relative to frost on microstructured superhydrophobic surfaces, which forms in the impaled Wenzel state. Dynamic defrosting on nanostructured superhydrophobic surfaces minimizes the time, heat, and gravitational energy required to remove frost from the surface, and is of interest for a variety of systems in cold and humid environments.

  3. Thermal Failure of Nanostructured Thermal Barrier Coatings with Cold-Sprayed Nanostructured NiCrAlY Bond Coat

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Li, Chang-Jiu; Li, Yong; Zhang, Shao-Ling; Wang, Xiu-Ru; Yang, Guan-Jun; Li, Cheng-Xin

    2008-12-01

    Nanostructured thermal barrier coatings (TBCs) were deposited by plasma spraying using agglomerated nanostructured YSZ powder on Inconel 738 substrate with cold-sprayed nanostructured NiCrAlY powder as bond coat. The isothermal oxidation and thermal cycling tests were applied to examine failure modes of plasma-sprayed nanostructured TBCs. For comparison, the TBC consisting of conventional microstructure YSZ and conventional NiCrAlY bond coat was also deposited and subjected to the thermal shock test. The results showed that nanostructured YSZ coating contained two kinds of microstructures; nanosized zirconia particles embedded in the matrix and microcolumnar grain structures of zirconia similar to those of conventional YSZ. Although, after thermal cyclic test, a continuous, uniform thermally grown oxide (TGO) was formed, cracks were observed at the interface between TGO/BC or TGO/YSZ after thermal cyclic test. However, the failure of nanostructured and conventional TBCs mainly occurred through spalling of YSZ. Compared with conventional TBCs, nanostructured TBCs exhibited better thermal shock resistance.

  4. Magneto Transport in Three Dimensional Carbon Nanostructures

    NASA Astrophysics Data System (ADS)

    Datta, Timir; Wang, Lei; Jaroszynski, Jan; Yin, Ming; Alameri, Dheyaa

    Electrical properties of self-assembled three dimensional nanostructures are interesting topic. Here we report temperature dependence of magneto transport in such carbon nanostructures with periodic spherical voids. Specimens with different void diameters in the temperature range from 200 mK to 20 K were studied. Above 2 K, magnetoresistance, MR = [R(B) - R(0)] / R(0), crosses over from quadratic to a linear dependence with the increase of magnetic field [Wang et al., APL 2015; DOI:10.1063/1.4926606]. We observe MR to be non-saturating even up to 18 Tesla. Furthermore, MR demonstrates universality because all experimental data can be collapsed on to a single curve, as a universal function of B/T. Below 2 K, magnetoresistance saturates with increasing field. Quantum Hall like steps are also observed in this low temperature regime. Remarkably, MR of our sample displays orientation independence, an attractive feature for technological applications.

  5. Large hysteretic magnetoresistance of silicide nanostructures

    NASA Astrophysics Data System (ADS)

    Kim, T.; Naser, B.; Chamberlin, R. V.; Schilfgaarde, M. V.; Bennett, P. A.; Bird, J. P.

    2007-11-01

    We demonstrate a large (as much as 100%) and strongly hysteretic magnetoresistance (MR) in nominally nonferromagnetic silicide films and nanowires. This unusual MR is quenched above a few kelvins, where conventional behavior due to weak antilocalization is recovered. The dynamic characteristics of this effect are suggestive of weakly interacting, localized paramagnetic moments that form at the surface oxide of the silicide nanostructures, with dramatic consequences for transport when the system size is reduced to the nanoscale.

  6. Design rule of nanostructures in light-emitting diodes for complete elimination of total internal reflection.

    PubMed

    Son, Jun Ho; Kim, Jong Uk; Song, Yang Hee; Kim, Buem Joon; Ryu, Chul Jong; Lee, Jong-Lam

    2012-05-02

    Cone-shaped nanostructures with controllable side-wall angle are success- fully fabricated with a SiO(2) nanosphere lithography (NSL) etching mask. Vertical LEDs with cone-shaped nanostructures with a 24.1° side-wall angle provide 6% more light output power compared to those using hexagonal pyramids formed by photochemical etching. This achievement is attributed to effective elimination of total internal reflection by angle-controlled nanostructures.

  7. Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures

    DTIC Science & Technology

    2008-09-22

    CdSe nanoparticles nanorods nanostructures photocatalysis semiconductors Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting...worldwide. Lawrence Berkeley National Laboratory Title: Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures Author...9rz418n4 Citation: Dukovic, Gordana. (2008). Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures . Lawrence Berkeley National

  8. EDITORIAL: Nanostructures + Light = 'New Optics'

    NASA Astrophysics Data System (ADS)

    Zheludev, Nikolay; Shalaev, Vladimir

    2005-02-01

    Suddenly, at the end of the last century, classical optics and classical electrodynamics became fashionable again. Fields that several generations of researchers thought were comprehensively covered by the famous Born and Wolf textbook and were essentially dead as research subjects were generating new excitement. In accordance with Richard Feynman’s famous quotation on nano-science, the optical community suddenly discovered that 'there is plenty of room at the bottom'—mixing light with small, meso- and nano-structures could generate new physics and new mind-blowing applications. This renaissance began when the concept of band structure was imported from electronics into the domain of optics and led to the development of what is now a massive research field dedicated to two- and three-dimensional photonic bandgap structures. The field was soon awash with bright new ideas and discoveries that consolidated the birth of the 'new optics'. A revision of some of the basic equations of electrodynamics led to the suspicion that we had overlooked the possibility that the triad of wave vector, electric field and magnetic field, characterizing propagating waves, do not necessarily form a right-handed set. This brought up the astonishing possibilities of sub-wavelength microscopy and telescopy where resolution is not limited by diffraction. The notion of meta-materials, i.e. artificial materials with properties not available in nature, originated in the microwave community but has been widely adopted in the domain of optical research, thanks to rapidly improving nanofabrication capabilities and the development of sub-wavelength scanning imaging techniques. Photonic meta-materials are expected to open a gateway to unprecedented electromagnetic properties and functionality unattainable from naturally occurring materials. The structural units of meta-materials can be tailored in shape and size; their composition and morphology can be artificially tuned, and inclusions can be

  9. Nano-structured titanium coating for improving biological performance.

    PubMed

    Xie, Youtao; Yang, Fei; Zheng, Xuebin; Ding, Chuanxian; Dai, Kerong; Huang, Liping

    2011-12-01

    Nano-structured titanium coating was obtained by alkali treating the vacuum plasma sprayed samples following hot water immersing for 24 h. The influences of the surface microstructure on the biological performance were studied. A canine model was applied for in vivo evaluation of the bone bonding ability of the coatings. The histological examination results demonstrate that new bone was formed more rapidly on the nano-structured coating implants and grew into the porosity than the as-sprayed one. After 4 weeks implantation, the nano-structured implants were found to appose directly to the surrounding bone while large lacunae could still be observed at the interface between the as-sprayed samples and bone. All these results indicate that a nano-structured surface on the porous titanium coating is favorable for bone bonding.

  10. ZnS:Cr Nanostructures Building Fractals and Their Properties

    SciTech Connect

    Gogoi, D. P.; Das, U.; Mohanta, D.; Ahmed, G. A.; Choudhury, A.

    2010-10-04

    Cr doped ZnS nanostructures have been fabricated through colloidal solution route by using Polyvinyl alcohol (-C{sub 2}H{sub 4}O){sub n} and Polyvinyl pyrrolidone k30 (C{sub 6}H{sub 9}NO){sub x} as dielectric hosts. Growth of fractal structures have been observed through Transmission Electron Microscopy. Higher magnification TEM study reveals that these fractals actually a organize structure of ZnS:Cr nanostructures. The structural study of these nanostructures in the fractals is done by X-Ray Diffraction, UV-Visible spectroscopy, Photoluminescence spectroscopy AFM and MFM. These investigations allow us to form a comprehensive explanation of fractal as well as nanostructure growth. We have done dimensional study of these fractals and the reason behind the formation of these fractals.

  11. Manganese Nanostructures and Magnetism

    NASA Astrophysics Data System (ADS)

    Simov, Kirie Rangelov

    The primary goal of this study is to incorporate adatoms with large magnetic moment, such as Mn, into two technologically significant group IV semiconductor (SC) matrices, e.g. Si and Ge. For the first time in the world, we experimentally demonstrate Mn doping by embedding nanostructured thin layers, i.e. delta-doping. The growth is observed by in-situ scanning tunneling microscopy (STM), which combines topographic and electronic information in a single image. We investigate the initial stages of Mn monolayer growth on a Si(100)(2x1) surface reconstruction, develop methods for classification of nanostructure types for a range of surface defect concentrations (1.0 to 18.2%), and subsequently encapsulate the thin Mn layer in a SC matrix. These experiments are instrumental in generating a surface processing diagram for self-assembly of monoatomic Mn-wires. The role of surface vacancies has also been studied by kinetic Monte Carlo modeling and the experimental observations are compared with the simulation results, leading to the conclusion that Si(100)(2x1) vacancies serve as nucleation centers in the Mn-Si system. Oxide formation, which happens readily in air, is detrimental to ferromagnetism and lessens the magnetic properties of the nanostructures. Therefore, the protective SC cap, composed of either Si or Ge, serves a dual purpose: it is both the embedding matrix for the Mn nanostructured thin film and a protective agent for oxidation. STM observations of partially deposited caps ensure that the nanostructures remain intact during growth. Lastly, the relationship between magnetism and nanostructure types is established by an in-depth study using x-ray magnetic circular dichroism (XMCD). This sensitive method detects signals even at coverages less than one atomic layer of Mn. XMCD is capable of discerning which chemical compounds contribute to the magnetic moment of the system, and provides a ratio between the orbital and spin contributions. Depending on the amount

  12. Biological features of biofilm-forming ability of Acinetobacter baumannii strains derived from 121 elderly patients with hospital-acquired pneumonia.

    PubMed

    Zhang, Duchao; Xia, Jingjing; Xu, Yaping; Gong, Meiliang; Zhou, Yu; Xie, Lixin; Fang, Xiangqun

    2016-02-01

    This study is to investigate a biological activity of Acinetobacter baumannii isolates from sputum specimens of 121 elderly patients with hospital-acquired pneumonia. The ability of the isolates to form biofilms was quantitatively assessed by crystal violet staining, and adhesive property was examined using Giemsa staining. Biofilm-forming ability by the isolates was employed to test antimicrobial resistance and examine sources and clinical manifestations. The isolates grew as biofilm on abiotic surface at the indicated temperatures after a 48 h of incubation. 27.3 % of the isolates were strongly biofilm-positive in the samples, and 84.8 % displayed high adhesion ability (P < 0.05). All of the isolates showed antibiotic resistance at different levels, and the isolates produced strong biofilm exhibited low-level resistance to gentamicin, minocycline and ceftazidime (P < 0.05). The patients' experience in ICU, use of antibiotics and estimation of APACHE II (<17) were related to incidence of strong biofilm formation with no clinical manifestations found in the study. All clinical isolates are able to form biofilms which refer to adhesive efficiency and antibiotic resistance. Patient experiences in ICU surveillance, use of antibiotics and APACHE II scores are involved in biofilm-forming ability by the nosocomial pathogen derived from the hospitalized patients.

  13. 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.

  14. Towards nano-organic chemistry: perspectives for a bottom-up approach to the synthesis of low-dimensional carbon nanostructures

    NASA Astrophysics Data System (ADS)

    Mercuri, Francesco; Baldoni, Matteo; Sgamellotti, Antonio

    2012-01-01

    Low-dimensional carbon nanostructures, such as nanotubes and graphenes, represent one of the most promising classes of materials, in view of their potential use in nanotechnology. However, their exploitation in applications is often hindered by difficulties in their synthesis and purification. Despite the huge efforts by the research community, the production of nanostructured carbon materials with controlled properties is still beyond reach. Nonetheless, this step is nowadays mandatory for significant progresses in the realization of advanced applications and devices based on low-dimensional carbon nanostructures. Although promising alternative routes for the fabrication of nanostructured carbon materials have recently been proposed, a comprehensive understanding of the key factors governing the bottom-up assembly of simple precursors to form complex systems with tailored properties is still at its early stages. In this paper, following a survey of recent experimental efforts in the bottom-up synthesis of carbon nanostructures, we attempt to clarify generalized criteria for the design of suitable precursors that can be used as building blocks in the production of complex systems based on sp2 carbon atoms and discuss potential synthetic strategies. In particular, the approaches presented in this feature article are based on the application of concepts borrowed from traditional organic chemistry, such as valence-bond theory and Clar sextet theory, and on their extension to the case of complex carbon nanomaterials. We also present and discuss a validation of these approaches through first-principle calculations on prototypical systems. Detailed studies on the processes involved in the bottom-up fabrication of low-dimensional carbon nanostructures are expected to pave the way for the design and optimization of precursors and efficient synthetic routes, thus allowing the development of novel materials with controlled morphology and properties that can be used in

  15. Bimetallic nanostructures as active Raman markers: gold-nanoparticle assembly on 1D and 2D silver nanostructure surfaces.

    PubMed

    Gunawidjaja, Ray; Kharlampieva, Eugenia; Choi, Ikjun; Tsukruk, Vladimir V

    2009-11-01

    It is demonstrated that bimetallic silver-gold anisotropic nanostructures can be easily assembled from various nanoparticle building blocks with well-defined geometries by means of electrostatic interactions. One-dimensional (1D) silver nanowires, two-dimensional (2D) silver nanoplates, and spherical gold nanoparticles are used as representative building blocks for bottom-up assembly. The gold nanoparticles are electrostatically bound onto the 1D silver nanowires and the 2D silver nanoplates to give bimetallic nanostructures. The unique feature of the resulting nanostructures is the particle-to-particle interaction that subjects absorbed analytes to an enhanced electromagnetic field with strong polarization dependence. The Raman activity of the bimetallic nanostructures is compared with that of the individual nanoparticle blocks by using rhodamine 6G solution as the model analyte. The Raman intensity of the best-performing silver-gold nanostructure is comparable with the dense array of silver nanowires and silver nanoplates that were prepared by means of the Langmuir-Blodgett technique. An optimized design of a single-nanostructure substrate for surface-enhanced Raman spectroscopy (SERS), based on a wet-assembly technique proposed here, can serve as a compact and low-cost alternative to fabricated nanoparticle arrays.

  16. Nanostructured Superhydrophobic Coatings

    SciTech Connect

    2009-03-01

    This factsheet describes a research project that deals with the nanostructured superhydrophobic (SH) powders developed at ORNL. This project seeks to (1) improve powder quality; (2) identify binders for plastics, fiberglass, metal (steel being the first priority), wood, and other products such as rubber and shingles; (3) test the coated product for coating quality and durability under operating conditions; and (4) application testing and production of powders in quantity.

  17. Macromolecular Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Ueyama, Norikazu; Harada, Akira

    This book presents a detailed account of the synthesis, characterization and application of organic and inorganic macromolecular nanostructured materials. These materials consist of simple organic compounds, inorganic complexes and polymers, and display unique properties such as electrical conductivity ranging from semiconducting to superconducting. Also described in the book are the roles of these materials in electrodeposition and gas deposition, as photosensitizers, magnets, macromolecular metal catalysts, sol-gel hybrids, and in biomineralization.

  18. Dynamic modeling and scaling of nanostructure formation in the lithographically induced self-assembly and self-construction

    NASA Astrophysics Data System (ADS)

    Wu, Lin; Chou, Stephen Y.

    2003-05-01

    We numerically studied the dynamical formation process and the scaling of the nanostructures in the lithographically induced self-assembly and self-construction of thin polymer films. Our studies show that the period of the self-assembled pillars depends on the ratio between the surface tension force and the electrostatic force. The viscosity of the polymer has no effect on the final pillar shape. When the feature width of the mold is comparable to or smaller than the most unstable disturbance wavelength of the system, the initially self-assembled pillars will merge to form a self-constructed mesa.

  19. Alternative nanostructures for thermophones.

    PubMed

    Aliev, Ali E; Mayo, Nathanael K; Jung de Andrade, Monica; Robles, Raquel O; Fang, Shaoli; Baughman, Ray H; Zhang, Mei; Chen, Yongsheng; Lee, Jae Ah; Kim, Seon Jeong

    2015-05-26

    Thermophones are highly promising for applications such as high-power SONAR arrays, flexible loudspeakers, and noise cancellation devices. So far, freestanding carbon nanotube aerogel sheets provide the most attractive performance as a thermoacoustic heat source. However, the limited accessibility of large-size freestanding carbon nanotube aerogel sheets and other even more exotic materials recently investigated hampers the field. We describe alternative materials for a thermoacoustic heat source with high-energy conversion efficiency, additional functionalities, environmentally friendly, and cost-effective production technologies. We discuss the thermoacoustic performance of alternative nanostructured materials and compare their spectral and power dependencies of sound pressure in air. We demonstrate that the heat capacity of aerogel-like nanostructures can be extracted by a thorough analysis of the sound pressure spectra. The study presented here focuses on engineering thermal gradients in the vicinity of nanostructures and subsequent heat dissipation processes from the interior of encapsulated thermoacoustic projectors. Applications of thermoacoustic projectors for high-power SONAR arrays, sound cancellation, and optimal thermal design, regarding enhanced energy conversion efficiency, are discussed.

  20. Sonoelectrochemical Approach Towards Nanostructures

    NASA Astrophysics Data System (ADS)

    Burda, Clemens; Qiu, Xiaofeng

    2006-03-01

    We will report on the sonoelectrochemical synthesis of nanostructured semiconductor materials. The talk will focus on the control of the nanostructure size, shape, and composition using sonolectrochemistry as a versatile synthesis tool. The synthesis of targeted nanostructures requires thorough control of the redox chemistry during the growth process. The composition of the product can be controlled by changing the initial metal-ligand concentration. Futhermore, the properties of the novel materials will be discussed. Powder X-ray diffraction of the products confirmed the compositional change in the nanomaterials. Control of the involved sonoelectrochemistry also allows for the formation of highly monodispersed 1-D Nanorods. Qiu, Xiaofeng; Lou, Yongbing; Samia, Anna C. S.; Devadoss, Anando; Burgess, James D.; Dayal, Smita; Burda, Clemens. PbTe nanorods by sonoelectrochemistry. Angewandte Chemie, International Edition (2005), 44(36), 5855-5857. Qiu, Xiaofeng; Burda, Clemens; Fu, Ruiling; Pu, Lin; Chen, Hongyuan; Zhu, Junjie. Heterostructured Bi2Se3 Nanowires with Periodic Phase Boundaries. Journal of the American Chemical Society (2004), 126(50), 16276-16277.

  1. Determination of structural and vibrational spectroscopic features of neutral and anion forms of dinicotinic acid by using NMR, infrared and Raman experimental methods combined with DFT and HF

    NASA Astrophysics Data System (ADS)

    Kose, E.; Bardak, F.; Atac, A.; Karabacak, M.; Cipiloglu, M. A.

    2013-10-01

    In this study; the experimental (NMR, infrared and Raman) and theoretical (HF and DFT) analysis of dinicotinic acid were presented. 1H and 13C NMR spectra were recorded in DMSO solution and chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of dinicotinic acid were recorded by FT-Raman and FT-IR spectra in the range of 4000-10 cm-1 and 4000-400 cm-1, respectively. To determine the most stable neutral conformer of molecule, the selected torsion angle was changed every 10° and molecular energy profile was calculated from 0° to 360°. The geometrical parameters and energies were obtained for all conformers form from density functional theory (DFT/B3LYP) and HF with 6-311++G(d,p) basis set calculations. However, the results of the most stable neutral and two anion forms (anion-1 and anion-2 forms) of dinicotinic acid are reported here. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational wavenumbers, calculated with scaled quantum mechanics (SQM) method and PQS program.

  2. Determination of structural and vibrational spectroscopic features of neutral and anion forms of dinicotinic acid by using NMR, infrared and Raman experimental methods combined with DFT and HF.

    PubMed

    Kose, E; Bardak, F; Atac, A; Karabacak, M; Cipiloglu, M A

    2013-10-01

    In this study; the experimental (NMR, infrared and Raman) and theoretical (HF and DFT) analysis of dinicotinic acid were presented. (1)H and (13)C NMR spectra were recorded in DMSO solution and chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of dinicotinic acid were recorded by FT-Raman and FT-IR spectra in the range of 4000-10 cm(-1) and 4000-400 cm(-1), respectively. To determine the most stable neutral conformer of molecule, the selected torsion angle was changed every 10° and molecular energy profile was calculated from 0° to 360°. The geometrical parameters and energies were obtained for all conformers form from density functional theory (DFT/B3LYP) and HF with 6-311++G(d,p) basis set calculations. However, the results of the most stable neutral and two anion forms (anion(-1) and anion(-2) forms) of dinicotinic acid are reported here. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational wavenumbers, calculated with scaled quantum mechanics (SQM) method and PQS program.

  3. Magnetic domain wall manipulation in (Ga,Mn)As nanostructures for spintronic applications

    SciTech Connect

    Wosinski, Tadeusz; Andrearczyk, Tomasz; Figielski, Tadeusz; Olender, Karolina; Wrobel, Jerzy

    2014-02-21

    Ring-shaped nanostructures have been designed and fabricated by electron-beam lithography patterning and chemical etching from thin epitaxial layers of the ferromagnetic semiconductor (Ga,Mn)As. The nanostructures, in a form of planar rings with a slit, were supplied with four electrical terminals and subjected to magneto-transport studies under planar weak magnetic field. Magnetoresistive effects caused by manipulation of magnetic domain walls and magnetization reversal in the nanostructures have been investigated and possible applications of the nanostructures as four-terminal spintronic devices are discussed.

  4. Polaronic effects on diamagnetic susceptibility of a hydrogenic donor in nanostructures

    NASA Astrophysics Data System (ADS)

    Jeice, A. R.; Jayam G., Sr.; Wilson, K. S. J.

    2016-07-01

    The binding energy and diamagnetic susceptibility of a hydrogenic donor in nanostructures like quantum well, quantum wire and quantum dot have been calculated for the finite and infinite barrier square well potential and are computed using variational technique. The binding energy of cubic nanostructures formed by GaAs/Ga1- x Al x As has also been obtained using conduction band non-parabolicity and polaronic correction. Our results demonstrate that the effect of polaronic mass and band non-parabolicity which exhibits effective binding energy and diamagnetic susceptibility for the nanostructures having narrow width sizes and it is not significant to the low dimensional nanostructures.

  5. Tuning the Fabrication of Nanostructures by Low-Energy Highly Charged Ions.

    PubMed

    El-Said, Ayman S; Wilhelm, Richard A; Heller, Rene; Sorokin, Michael; Facsko, Stefan; Aumayr, Friedrich

    2016-09-16

    Slow highly charged ions have been utilized recently for the creation of monotype surface nanostructures (craters, calderas, or hillocks) in different materials. In the present study, we report on the ability of slow highly charged xenon ions (^{129}Xe^{Q+}) to form three different types of nanostructures on the LiF(100) surface. By increasing the charge state from Q=15 to Q=36, the shape of the impact induced nanostructures changes from craters to hillocks crossing an intermediate stage of caldera structures. A dimensional analysis of the nanostructures reveals an increase of the height up to 1.5 nm as a function of the potential energy of the incident ions. Based on the evolution of both the geometry and size of the created nanostructures, defect-mediated desorption and the development of a thermal spike are utilized as creation mechanisms of the nanostructures at low and high charge states, respectively.

  6. Hollow Nanostructured Metal Silicates with Tunable Properties for Lithium Ion Battery Anodes.

    PubMed

    Yu, Seung-Ho; Quan, Bo; Jin, Aihua; Lee, Kug-Seung; Kang, Soon Hyung; Kang, Kisuk; Piao, Yuanzhe; Sung, Yung-Eun

    2015-11-25

    Hollow nanostructured materials have attracted considerable interest as lithium ion battery electrodes because of their good electrochemical properties. In this study, we developed a general procedure for the synthesis of hollow nanostructured metal silicates via a hydrothermal process using silica nanoparticles as templates. The morphology and composition of hollow nanostructured metal silicates could be controlled by changing the metal precursor. The as-prepared hierarchical hollow nanostructures with diameters of ∼100-200 nm were composed of variously shaped primary particles such as hollow nanospheres, solid nanoparticles, and thin nanosheets. Furthermore, different primary nanoparticles could be combined to form hybrid hierarchical hollow nanostructures. When hollow nanostructured metal silicates were applied as anode materials for lithium ion batteries, all samples exhibited good cyclic stability during 300 cycles, as well as tunable electrochemical properties.

  7. Enantioselective control of lattice and shape chirality in inorganic nanostructures using chiral biomolecules.

    PubMed

    Ben-Moshe, Assaf; Wolf, Sharon Grayer; Bar Sadan, Maya; Houben, Lothar; Fan, Zhiyuan; Govorov, Alexander O; Markovich, Gil

    2014-07-08

    A large number of inorganic materials form crystals with chiral symmetry groups. Enantioselectively synthesizing nanostructures of such materials should lead to interesting optical activity effects. Here we report the synthesis of colloidal tellurium and selenium nanostructures using thiolated chiral biomolecules. The synthesis conditions are tuned to obtain tellurium nanostructures with chiral shapes and large optical activity. These nanostructures exhibit visible optical and chiroptical responses that shift with size and are successfully simulated by an electromagnetic model. The model shows that they behave as chiral optical resonators. The chiral tellurium nanostructures are transformed into chiral gold and silver telluride nanostructures with very large chiroptical activity, demonstrating a simple colloidal chemistry path to chiral plasmonic and semiconductor metamaterials. These materials are natural candidates for studies related to interactions of chiral (bio)molecules with chiral inorganic surfaces, with relevance to asymmetric catalysis, chiral crystallization and the evolution of homochirality in biomolecules.

  8. Tuning the Fabrication of Nanostructures by Low-Energy Highly Charged Ions

    NASA Astrophysics Data System (ADS)

    El-Said, Ayman S.; Wilhelm, Richard A.; Heller, Rene; Sorokin, Michael; Facsko, Stefan; Aumayr, Friedrich

    2016-09-01

    Slow highly charged ions have been utilized recently for the creation of monotype surface nanostructures (craters, calderas, or hillocks) in different materials. In the present study, we report on the ability of slow highly charged xenon ions (129Xe Q+ ) to form three different types of nanostructures on the LiF(100) surface. By increasing the charge state from Q =15 to Q =36 , the shape of the impact induced nanostructures changes from craters to hillocks crossing an intermediate stage of caldera structures. A dimensional analysis of the nanostructures reveals an increase of the height up to 1.5 nm as a function of the potential energy of the incident ions. Based on the evolution of both the geometry and size of the created nanostructures, defect-mediated desorption and the development of a thermal spike are utilized as creation mechanisms of the nanostructures at low and high charge states, respectively.

  9. Tailored magnetic nanostructures on surfaces

    NASA Astrophysics Data System (ADS)

    Pierce, John Philip

    Nanostructuring has introduced us to a new world of tunable, artificially structured materials. An exciting aspect of this new world is that we control where the atoms, or layers of atoms, are arranged in materials and have learned that this can awaken new properties in them. But, we are only at the beginning stages in developing this control and an understanding of what can be done with it. This dissertation is about an important part of finding our way in this new world; learning to tailor magnetic nanostructures on surfaces. We begin by showing ways in which the magnetic properties of ultrathin films, nanostripes, and isolated nanoclusters can be systematically varied in order to teach us about their behavior. The ultrathin films are from the historically challenging Fe/Cu(100) system. We use small fractions of a single layer of cobalt capping atoms to control their magnetization direction and find a completely new way to cause the magnetization direction to reorient. The nanostripes are made of alloys of iron and cobalt on a tungsten surface. We explore how the magnetic ordering in these stripes is affected by variation of their composition. We then show how changing the size and spacing of isolated Fe dots on a copper surface can teach us about magnetic interactions between them. Finally, we show how our ability to synthesize the dots represented the last piece in an important puzzle. This work enables us to make the first direct observation of how the magnetic properties of a particular amount of a single material change as it is prepared in the form of an ultrathin film, wire array, or dot assembly on a common template.

  10. Field Emission and Nanostructure of Carbon Films

    SciTech Connect

    Merkulov, V.I.; Lowndes, D.H.; Baylor, L.R.

    1999-11-29

    The results of field emission measurements of various forms of carbon films are reported. It is shown that the films nanostructure is a crucial factor determining the field emission properties. In particular, smooth, pulsed-laser deposited amorphous carbon films with both high and low sp3 contents are poor field emitters. This is similar to the results obtained for smooth nanocrystalline, sp2-bonded carbon films. In contrast, carbon films prepared by hot-filament chemical vapor deposition (HE-CVD) exhibit very good field emission properties, including low emission turn-on fields, high emission site density, and excellent durability. HF-CVD carbon films were found to be predominantly sp2-bonded. However, surface morphology studies show that these films are thoroughly nanostructured, which is believed to be responsible for their promising field emission properties.

  11. Nanowires, nanostructures and devices fabricated therefrom

    DOEpatents

    Majumdar, Arun; Shakouri, Ali; Sands, Timothy D.; Yang, Peidong; Mao, Samuel S.; Russo, Richard E.; Feick, Henning; Weber, Eicke R.; Kind, Hannes; Huang, Michael; Yan, Haoquan; Wu, Yiying; Fan, Rong

    2005-04-19

    One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as "nanowires", include single-crystalline homostructures as well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN).

  12. Metal plasmas for the fabrication of nanostructures

    SciTech Connect

    Anders, Andre

    2006-09-21

    A review is provided covering metal plasma production, theenergetic condensation of metal plasmas, and the formation ofnanostructures using such plasmas. Plasma production techniques includepulsed laser ablation, filtered cathodic arcs, and various forms ofionized physical vapor deposition, namely magnetron sputtering withionization of sputtered atoms in radio frequency discharges,self-sputtering, and high power impulse magnetron sputtering. Thediscussion of energetic condensation focuses on the control of kineticenergy by biasing and also includes considerations of the potentialenergy and the processes occurring at subplantation and implantation. Inthe final section on nanostructures, two different approaches arediscussed. In the top-down approach, the primary nanostructures arelithographically produced and metal plasma is used to coat or filltrenches and vias. Additionally, multilayers with nanosize periods(nanolaminates) can be produced. In the bottom-up approach, thermodynamicforces are used to fabricate nanocomposites and nanoporous materials bydecomposition and dealloying.

  13. Nanostructured cathode materials for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Myung, Seung-Taek; Amine, Khalil; Sun, Yang-Kook

    2015-06-01

    The prospect of drastic climate change and the ceaseless fluctuation of fossil fuel prices provide motivation to reduce the use of fossil fuels and to find new energy conversion and storage systems that are able to limit carbon dioxide generation. Among known systems, lithium-ion batteries are recognized as the most appropriate energy storage system because of their high energy density and thus space saving in applications. Introduction of nanotechnology to electrode material is beneficial to improve the resulting electrode performances such as capacity, its retention, and rate capability. The nanostructure is highly available not only when used alone but also is more highlighted when harmonized in forms of core-shell structure and composites with carbon nanotubes, graphene or reduced graphene oxides. This review covers syntheses and electrochemical properties of nanoscale, nanosized, and nanostructured cathode materials for rechargeable lithium batteries.

  14. Self-assembled Oniontype Multiferroic Nanostructures

    NASA Astrophysics Data System (ADS)

    Ren, Shenqiang; Briber, Robert M.; Wuttig, Manfred

    2009-03-01

    Spontaneously self-assembled oniontype multiferroic nanostructures based on block copolymers as templating materials are reported. Diblock copolymer containing two different magnetoelectric precursors separately segregated to the two microdomains have been shown to form well-ordered templated lamellar structures. Onion-type multilamellar ordered multiferroic (PZT/CoFe2O4) nanostructures have been induced by room temperature solvent annealing in a magnetic field oriented perpendicular to the plane of the film. The evolution of the onion-like microstructure has been characterized by AFM, MFM, and TEM. The structure retains lamellar periodicity observed at zero field. The onion structure is superparamagnetic above and antiferromagnetic below the blocking temperature. This templating process opens a route for nanometer-scale patterning of magnetic toroids by means of self-assembly on length scales that are difficult to obtain by standard lithography techniques.

  15. Precipitate strengthening of nanostructured aluminium alloy.

    PubMed

    Wawer, Kinga; Lewandowska, Malgorzata; Kurzydlowski, Krzysztof J

    2012-11-01

    Grain boundaries and precipitates are the major microstructural features influencing the mechanical properties of metals and alloys. Refinement of the grain size to the nanometre scale brings about a significant increase in the mechanical strength of the materials because of the increased number of grain boundaries which act as obstacles to sliding dislocations. A similar effect is obtained if nanoscale precipitates are uniformly distributed in coarse grained matrix. The development of nanograin sized alloys raises the important question of whether or not these two mechanisms are "additive" and precipitate strengthening is effective in nanostructured materials. In the reported work, hydrostatic extrusion (HE) was used to obtain nanostructured 7475 aluminium alloy. Nanosized precipitates were obtained by post-HE annealing. It was found that such annealing at the low temperatures (100 degrees C) results in a significant increase in the microhardness (HV0.2) and strength of the nanostructured 7475 aluminium alloy. These results are discussed in terms of the interplay between the precipitation and deformation of nanocrystalline metals.

  16. Subwavelength resonant nanostructured films for sensing

    SciTech Connect

    Alvine, Kyle J.; Bernacki, Bruce E.; Suter, Jonathan D.; Bennett, Wendy D.; Edwards, Daniel L.; Mendoza, Albert

    2013-05-29

    We present a novel subwavelength nanostructure architecture that may be utilized for optical standoff sensing applications. The subwavelength structures are fabricated via a combination of nanoimprint lithography and metal sputtering to create metallic nanostructured films encased within a transparent media. The structures are based on the open ring resonator (ORR) architecture and have their analog in resonant LC circuits, which display a resonance frequency that is inversely proportional to the square root of the product of the inductance and capacitance. Therefore, any perturbation of the nanostructured films due to chemical or environmental effects can alter the inductive or capacitive behavior of the subwavelength features, which can shift the resonant frequency and provide an indication of the external stimulus. This shift in resonance can be interrogated remotely either actively using either laser illumination or passively using hyperspectral or multispectral sensing. These structures may be designed to be either anisotropic or isotropic, which can also provide polarization-sensitive interrogation. Due to the nanometer-scale of the structures, they can be tailored to be optically responsive in the visible or near infrared spectrum with a highly reflective resonant peak that is dependent solely on structural dimensions and material characteristics. We present experimental measurements of the optical response of these structures as a function of wavelength, polarization, and incident angle demonstrating the resonant effect in the near infrared region. Numerical modeling data showing the effect of different fabrication parameters such as structure parameters are also discussed.

  17. Responsive nanostructures from aqueous assembly of rigid-flexible block molecules.

    PubMed

    Kim, Ho-Joong; Kim, Taehoon; Lee, Myongsoo

    2011-01-18

    During the past decade, supramolecular nanostructures produced via self-assembly processes have received considerable attention because these structures can lead to dynamic materials. Among these diverse self-assembly systems, the aqueous assemblies that result from the sophisticated design of molecular building blocks offer many potential applications for producing biocompatible materials that can be used for tissue regeneration, drug delivery, and ion channel regulation. Along this line, researchers have synthesized self-assembling molecules based on ethylene oxide chains and peptide building blocks to exploit water-soluble supramolecular structures. Another important issue in the development of systems that self-assemble is the introduction of stimuli-responsive functions into the nanostructures. Recently, major efforts have been undertaken to develop responsive nanostructures that respond to applied stimuli and dynamically undergo defined changes, thereby producing switchable properties. As a result, this introduction of stimuli-responsive functions into aqueous self-assembly provides an attractive approach for the creation of novel nanomaterials that are capable of responding to environmental changes. This Account describes recent work in our group to develop responsive nanostructures via the self-assembly of small block molecules based on rigid-flexible building blocks in aqueous solution. Because the rigid-flexible molecules self-assemble into nanoscale aggregates through subtle anisometric interactions, the small variations in local environments trigger rapid transformation of the equilibrium features. First, we briefly describe the general self-assembly of the rod amphiphiles based on a rigid-flexible molecular architecture in aqueous solution. We then highlight the structural changes and the optical/macroscopic switching that occurs in the aqueous assemblies in response to the external signals. For example, the aqueous nanofibers formed through the self

  18. Ordered Nanostructures Made Using Chaperonin Polypeptides

    NASA Technical Reports Server (NTRS)

    Trent, Jonathan; McMillan, Robert; Paavola, Chad; Mogul, Rakesh; Kagawa, Hiromi

    2004-01-01

    A recently invented method of fabricating periodic or otherwise ordered nanostructures involves the use of chaperonin polypeptides. The method is intended to serve as a potentially superior and less expensive alternative to conventional lithographic methods for use in the patterning steps of the fabrication of diverse objects characterized by features of the order of nanometers. Typical examples of such objects include arrays of quantum dots that would serve as the functional building blocks of future advanced electronic and photonic devices. A chaperonin is a double-ring protein structure having a molecular weight of about 60 plus or minus 5 kilodaltons. In nature, chaperonins are ubiquitous, essential, subcellular structures. Each natural chaperonin molecule comprises 14, 16, or 18 protein subunits, arranged as two stacked rings approximately 16 to 18 nm tall by approximately 15 to 17 nm wide, the exact dimensions depending on the biological species in which it originates. The natural role of chaperonins is unknown, but they are believed to aid in the correct folding of other proteins, by enclosing unfolded proteins and preventing nonspecific aggregation during assembly. What makes chaperonins useful for the purpose of the present method is that under the proper conditions, chaperonin rings assemble themselves into higher-order structures. This method exploits such higher-order structures to define nanoscale devices. The higher-order structures are tailored partly by choice of chemical and physical conditions for assembly and partly by using chaperonins that have been mutated. The mutations are made by established biochemical techniques. The assembly of chaperonin polypeptides into such structures as rings, tubes, filaments, and sheets (two-dimensional crystals) can be regulated chemically. Rings, tubes, and filaments of some chaperonin polypeptides can, for example, function as nano vessels if they are able to absorb, retain, protect, and release gases or

  19. Click modification of diazido acridine intercalators: a versatile route towards decorated DNA nanostructures.

    PubMed

    Moradpour Hafshejani, Shahrbanou; Watson, Scott M D; Tuite, Eimer M; Pike, Andrew R

    2015-09-01

    Diazido derivatives of 3,6-diamino acridine (proflavine) intercalate into DNA and undergo functionalization through click chemistry to form 1D nanostructures with redox active, conductive nanowire, and fluorescent properties. This two-step approach, intercalation followed by click modification allows for the controlled decoration of DNA nanostructures.

  20. Helium entrapment in a nanostructured ferritic alloy

    SciTech Connect

    Edmondson, Philip D; Parish, Chad M; Zhang, Yanwen; Hallen, Dr Anders; Miller, Michael K

    2011-01-01

    The nanostructured ferritic alloy 14YWT has been irradiated with He ions to simulate accumulation of He during the service life of a nuclear reactor to test the hypothesis that the large surface area for nanoclusters is a preferential nucleation site for bubbles. Transmission electron microscopy and atom probe tomography showed that high number densities of He bubbles were formed on the surface of nanoclusters and Ti(C,N) precipitates, and along grain boundaries and dislocations. At higher fluences, facetted bubbles are formed and it is postulated that the lowest energy state configuration is the truncated rhombic dodecahedron.

  1. Class III alcohol dehydrogenase from Saccharomyces cerevisiae: structural and enzymatic features differ toward the human/mammalian forms in a manner consistent with functional needs in formaldehyde detoxication.

    PubMed

    Fernández, M R; Biosca, J A; Norin, A; Jörnvall, H; Parés, X

    1995-08-14

    Alcohol dehydrogenase class III (glutathione-dependent formaldehyde dehydrogenase) from Saccharomyces cerevisiae was purified and analyzed structurally and enzymatically. The corresponding gene was also analyzed after cloning from a yeast genome library by screening with a probe prepared through PCR amplification. As with class III alcohol dehydrogenase from other sources, the yeast protein was obtained in two active forms, deduced to reflect different adducts/modifications. Protein analysis established N-terminal and C-terminal positions, showing different and specific patterns in protein start positions between the human/mammalian, yeast, and prokaryotic forms. Km values with formaldehyde differ consistently, being about 10-fold higher in the yeast than the human/mammalian enzymes, but compensated for by similar changes in kcat values. This is compatible with the different functional needs, emphasizing low formaldehyde concentration in the animal cells but efficient formaldehyde elimination in the microorganisms. This supports a general role of the enzyme in formaldehyde detoxication rather than in long-chain alcohol turnover.

  2. Early clinical and electrophysiologic features of the two most common autosomal recessive forms of Charcot-Marie-Tooth disease in the Roma (Gypsies).

    PubMed

    Guergueltcheva, Velina; Tournev, Ivailo; Bojinova, Veneta; Hantke, Janina; Litvinenko, Ivan; Ishpekova, Boryana; Shmarov, Alexander; Petrova, Julia; Jordanova, Albena; Kalaydjieva, Luba

    2006-01-01

    Our recent studies of the genetic epidemiology of neuromuscular disorders in Gypsies in Bulgaria have revealed that two private disorders, hereditary motor and sensory neuropathy type Lom and hereditary motor and sensory neuropathy type Russe, account for most cases of Charcot-Marie-Tooth disease in this population. In this study, we examined the clinical and electrophysiologic manifestations of the two disorders in childhood, aiming to identify the distinctive features that allow early differential diagnosis. The study included 13 patients, aged between 2 and 15 years. The childhood clinical manifestations of both neuropathies were similar, although they tended to be more severe in hereditary motor and sensory neuropathy type Lom. The nerve conduction velocities in hereditary motor and sensory neuropathy type Lom were lower than in hereditary motor and sensory neuropathy type Russe. Brainstem auditory evoked potentials were abnormal in hereditary motor and sensory neuropathy type Lom, even at an early age, and normal in hereditary motor and sensory neuropathy type Russe. Although electrophysiologic data provide a more reliable differentiation than clinical data, the definitive diagnosis should rely on genetic testing. (J Child Neurol 2006;21:20-25).

  3. Ion-sensing properties of 1D vanadium pentoxide nanostructures

    PubMed Central

    2012-01-01

    The application of one-dimensional (1D) V2O5·nH2O nanostructures as pH sensing material was evaluated. 1D V2O5·nH2O nanostructures were obtained by a hydrothermal method with systematic control of morphology forming different nanostructures: nanoribbons, nanowires and nanorods. Deposited onto Au-covered substrates, 1D V2O5·nH2O nanostructures were employed as gate material in pH sensors based on separative extended gate FET as an alternative to provide FET isolation from the chemical environment. 1D V2O5·nH2O nanostructures showed pH sensitivity around the expected theoretical value. Due to high pH sensing properties, flexibility and low cost, further applications of 1D V2O5·nH2O nanostructures comprise enzyme FET-based biosensors using immobilized enzymes. PMID:22709724

  4. Crystalline Gaq3 Nanostructures: Preparation, Thermal Property and Spectroscopy Characterization

    NASA Astrophysics Data System (ADS)

    Yu, Ya-Wen; Cho, Chun-Pei; Perng, Tsong-Pyng

    2009-08-01

    Crystalline Gaq3 1-D nanostructures and nanospheres could be fabricated by thermal evaporation under cold trap. The influences of the key process parameters on formation of the nanostructures were also investigated. It has been demonstrated that the morphology and dimension of the nanostructures were mainly controlled by working temperature and working pressure. One-dimensional nanostructures were fabricated at a lower working temperature, whereas nanospheres were formed at a higher working temperature. Larger nanospheres could be obtained when a higher working pressure was applied. The XRD, FTIR, and NMR analyses evidenced that the nanostructures mainly consisted of δ-phase Gaq3. Their DSC trace revealed two small exothermic peaks in addition to the melting endotherm. The one in lower temperature region was ascribed to a transition from δ to β phase, while another in higher temperature region could be identified as a transition from β to δ phase. All the crystalline nanostructures show similar PL spectra due to absence of quantum confinement effect. They also exhibited a spectral blue shift because of a looser interligand spacing and reduced orbital overlap in their δ-phase molecular structures.

  5. Method for forming cooperative binary ionic solids

    DOEpatents

    Shelnutt, John A.; Martin, Kathleen E.; Wang, Zhongchun; Medforth, Craig J.

    2014-09-09

    A nanostructured molecular unit and method for forming is described where a cationic porphyrin having an ethanolic substituent species and a metal in the porphyrin cavity is combined with an anionic porphyrin having a sulfonate substituent species and a metal in the porphyrin cavity to form by self-assembly a nanostructured molecular unit with a morphology comprising four dendritic elements connected at a central node.

  6. Method for forming cooperative binary ionic solids

    DOEpatents

    Shelnutt, John A.; Martin, Kathleen E.; Wang, Zhongchun; Medforth, Craig J.

    2013-03-05

    A nanostructured molecular unit and method for forming is described where a cationic porphyrin having an ethanolic substituent species and a metal in the porphyrin cavity is combined with an anionic porphyrin having a sulfonate substituent species and a metal in the porphyrin cavity to form by self-assembly a nanostructured molecular unit with a morphology comprising four dendritic elements connected at a central node.

  7. Bioindication of trace metals in Brachythecium rutabulum around a copper smelter in Legnica (Southwest Poland): Use of a new form of data presentation in the form of a self-organizing feature map.

    PubMed

    Samecka-Cymerman, A; Stankiewicz, A; Kolon, K; Kempers, A J

    2009-05-01

    Concentrations of the elements Al, Be, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were measured in the terrestrial moss Brachythecium rutabulum and the soil on which it grew. Soil and moss plants were sampled at sites situated 1.5, 3, 6, 9 and 15 km to the north, south, east and west of the Legnica copper smelter (SW Poland). The self-organizing feature map (SOFM) or Kohonen network was used to classify the soil and moss samples according to the concentrations of the elements. The self-organizing map yielded distinct groups of B. rutabulum and soil samples, depending on the distance from and direction to the source of pollution. When the map-identified groups of sites with similar soil metal concentrations were combined with the map-identified groups of sites with similar metal concentrations in B. rutabulum, these maps were found to correspond closely. The SOFMs accurately represented the least polluted, moderately polluted and severely polluted sites, reflecting the distribution of metals that is typical of the smelter area, caused by the prevailing westerly and northerly winds.

  8. Molecularly Designed Ultrafine/Nanostructured Materials

    DTIC Science & Technology

    1994-04-08

    MIateria ls. NIT.3 Weber . P). 1.ecoq - R.C. R mnehti C. N\\uods. W.\\I. Yen. R,-Y. /.Iiu. 1994. ISB.N: 1-55S99-2󈧴-0 Volume 349- Nowel FI iins in au hon...precursor pOder to the desired nanostructured composite powder through controlled gas-solid reactions. The thermodynamic and kinetic features .q the gas-solid...279 4. H.D. Fuchs. M.S. Brandt. M. Stutzmann, J. Weber , Mat. Res. Soc. Symp. Proc. 256, 159 (1992). 5. MIJ Sallor. K.L. Kavanagh, Adv. Mater. 4, 432

  9. Highly sensitive NIR PtSi/Si-nanostructure detectors

    NASA Astrophysics Data System (ADS)

    Li, Hua-gao; Guo, Pei; Yuan, An-bo; Long, Fei; Li, Rui-zhi; Li, Ping; Li, Yi

    2016-10-01

    We report a high external quantum efficiency (EQE) photodiode detector with PtSi/Si-nanostructures. Black silicon nanostructures were fabricated by metal-assist chemical etching (MCE), a 2 nm Pt layer was subsequently deposited on black silicon surface by DC magnetron sputtering system, and PtSi/Si-nanostructures were formed in vacuum annealing at 450 oC for 5 min. As the PtSi/Si-nanostructures presented a spiky shape, the absorption of incident light was remarkably enhanced for the repeat reflection and absorption. The breakdown voltage, dark current, threshold voltage and responsivity of the device were investigated to evaluate the performance of the PtSi/Si-nanostructures detector. The threshold voltage and dark currents of the PtSi/Si-nanostructure photodiode tends to be slightly higher than those of the standard diodes. The breakdown voltage remarkably was reduced because of existing avalanche breakdown in PtSi/Si-nanostructures. However, the photodiodes had high response at room temperature in near infrared region. At -5 V reverse bias voltage, the responsivity was 0.72 A/W in 1064 nm wavelength, and the EQE was 83.9%. By increasing the reverse bias voltage, the responsivity increased. At -60 V reverse bias voltage, the responsivity was 3.5 A/W, and the EQE was 407.5%, which means the quantum efficiency of PtSi/Si-nanostructure photodiodes was about 10 times higher than that of a standard diode. Future research includes how to apply this technology to enhance the NIR sensitivity of image sensors, such as Charge Coupled Devices (CCD).

  10. Bilinear form, bilinear Bäcklund transformation and dynamic features of the soliton solutions for a variable-coefficient (3+1)-dimensional generalized shallow water wave equation

    NASA Astrophysics Data System (ADS)

    Huang, Qian-Min; Gao, Yi-Tian

    2017-08-01

    Under investigation in this letter is a variable-coefficient (3+1)-dimensional generalized shallow water wave equation. Bilinear form and Bäcklund transformation are obtained. One-, two- and three-soliton solutions are derived via the Hirota bilinear method. Interaction and propagation of the solitons are discussed graphically. Stability of the solitons is studied numerically. Soliton amplitude is determined by the spectral parameters. Soliton velocity is not only related to the spectral parameters, but also to the variable coefficients. Phase shifts are the only difference between the two-soliton solutions and the superposition of the two relevant one-soliton solutions. Numerical investigation on the stability of the solitons indicates that the solitons could resist the disturbance of small perturbations and propagate steadily.

  11. Transverse Anderson localization of light near Dirac points of photonic nanostructures

    PubMed Central

    Deng, Hanying; Chen, Xianfeng; Malomed, Boris A.; Panoiu, Nicolae C.; Ye, Fangwei

    2015-01-01

    We perform a comparative study of the Anderson localization of light beams in disordered layered photonic nanostructures that, in the limit of periodic layer distribution, possess either a Dirac point or a Bragg gap in the spectrum of the wavevectors. In particular, we demonstrate that the localization length of the Anderson modes increases when the width of the Bragg gap decreases, such that in the vanishingly small bandgap limit, namely when a Dirac point is formed, even extremely high levels of disorder are unable to localize the optical modes residing near the Dirac point. A comparative analysis of the key features of the propagation of Anderson modes formed in the Bragg gap or near the Dirac point is also presented. Our findings could provide valuable guidelines in assessing the influence of structural disorder on the functionality of a broad array of optical nanodevices. PMID:26498634

  12. Transverse Anderson localization of light near Dirac points of photonic nanostructures.

    PubMed

    Deng, Hanying; Chen, Xianfeng; Malomed, Boris A; Panoiu, Nicolae C; Ye, Fangwei

    2015-10-26

    We perform a comparative study of the Anderson localization of light beams in disordered layered photonic nanostructures that, in the limit of periodic layer distribution, possess either a Dirac point or a Bragg gap in the spectrum of the wavevectors. In particular, we demonstrate that the localization length of the Anderson modes increases when the width of the Bragg gap decreases, such that in the vanishingly small bandgap limit, namely when a Dirac point is formed, even extremely high levels of disorder are unable to localize the optical modes residing near the Dirac point. A comparative analysis of the key features of the propagation of Anderson modes formed in the Bragg gap or near the Dirac point is also presented. Our findings could provide valuable guidelines in assessing the influence of structural disorder on the functionality of a broad array of optical nanodevices.

  13. Hybrid lipid-based nanostructures

    NASA Astrophysics Data System (ADS)

    Dayani, Yasaman

    then, using a sonication process, a uniform lipid bilayer that supports the incorporation of membrane proteins is formed. These bilayer-coated carbon nanotubes are highly dispersible and stable in aqueous solution, and they can be used in development of various biosensors and energy producing devices. In the other hybrid nanostructure, the lipid bilayer of a liposome is covalently anchored to a biocompatible poly(ethylene) glycol (PEG) hydrogel core using double-stranded DNA (dsDNA) linkers. Release studies shows that nano-size hydrogel-anchored liposomes are exceptionally stable, and they can be used as biomimetic model membranes that mimic the connectivity between the cytoskeleton and the plasma membrane. After lipid bilayer removal, dsDNA linkers can provide programmable nanogels decorated with oligonucleotides with potential sites for further molecular assembly. These stable nanostructures can be useful for oligonucleotide and drug delivery applications. The developed hydrogel-anchored liposomes are exploited for encapsulation and intracellular delivery of therapeutic peptide. Peptides with anti-cancer properties are successfully encapsulated in hydrogel core of pH-sensitive liposomes during rehydration process. Liposomes release their cargo at acidic pH. Confocal microscopy confirms the intracellular delivery of liposomes through an endocytotic pathway.

  14. Pomological features, nutritional quality, polyphenol content analysis, and antioxidant properties of domesticated and 3 wild ecotype forms of raspberries (Rubus idaeus L.).

    PubMed

    Gülçin, Ilhami; Topal, Fevzi; Çakmakçı, Ramazan; Bilsel, Mine; Gören, Ahmet C; Erdogan, Ummugulsum

    2011-05-01

    The raspberry (Rubus idaeus L.) is an economically important berry crop that contains many phenolic compounds with potential health benefits. In this study, important pomological features, including nutrient content and antioxidant properties, of a domesticated and 3 wild (Yayla, Yavuzlar, and Yedigöl) raspberry fruits were evaluated. Also, the amount of total phenolics and flavonoids in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were calculated as gallic acid equivalents (GAEs) and quercetin equivalents (QE). The highest phenolic compounds were found in wild Yayla ecotype (26.66 ± 3.26 GAE/mg extract). Whilst, the highest flavonoids were determined in wild Yedigöl ecotype (6.09 ± 1.21 QA/mg extract). The antioxidant activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were investigated as trolox equivalents using different in vitro assays including DPPH(•), ABTS(•+), DMPD(•+), and O(•-)(2) radical scavenging activities, H(2)O(2) scavenging activity, ferric (Fe(3+)) and cupric ions (Cu(2+)) reducing abilities, ferrous ions (Fe(2+)) chelating activity. In addition, quantitative amounts of caffeic acid, ferulic acid, syringic acid, ellagic acid, quercetin, α-tocopherol, pyrogallol, p-hydroxybenzoic acid, vanillin, p-coumaric acid, gallic acid, and ascorbic acid in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were detected by high-performance liquid chromatography and tandem mass spectrometry (LC-MS-MS). The results clearly show that p-coumaric acid is the main phenolic acid responsible for the antioxidant and radical scavenging activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits. © 2011 Institute of Food Technologists®

  15. One-dimensional metal oxide nanostructures for heterogeneous catalysis.

    PubMed

    Zhang, Qian; Wang, Hsin-Yi; Jia, Xinli; Liu, Bin; Yang, Yanhui

    2013-08-21

    Metal oxides are of paramount importance in heterogeneous catalysis as either supports or active phases. Controlled synthesis of one-dimensional (1D) metal oxide nanostructures has received enormous attention in heterogeneous catalysis due to the possibility of tailoring the properties of metal oxides by tuning their shapes, sizes, and compositions. This feature article highlights recent advances in shape controlled synthesis of 1D metal oxide nanostructures and their applications in heterogeneous catalysis, with the aim of introducing new insights into the heterogeneous catalyst design.

  16. The effect of solvent on the morphology of ZnO nanostructure assembly by dielectrophoresis and its device applications.

    PubMed

    La Ferrara, Vera; Pacheri Madathil, Aneesh; De Girolamo Del Mauro, Anna; Massera, Ettore; Polichetti, Tiziana; Rametta, Gabriella

    2012-07-01

    Different zinc oxide nanostructured morphologies were grown on photolithographically patterned silicon/silicon dioxide substrates by dielectrophoresis technique using different solvents, such as water and ethanol, obtaining rod-like and net-like nanostructures, respectively. The formation of continuous nanostructures was confirmed by scanning electron microscopic, atomic force microscopic images, and electrical characterizations. The rod-like zinc oxide nanostructures were observed in the 10 μm gap between the fingers in the pattern, whereas net-like nanostructures were formed independently of microgap. A qualitative study about the mechanism for the assembly of zinc oxide continuous nanostructures was presented. Devices were electrically characterized, at room temperature, in controlled environment to measure the conductance behavior in ultraviolet and humidity environment. Devices based on zinc oxide nanostructures grown in ethanol medium show better responses under both ultraviolet and humidity, because of the net-like structure with high surface-to-volume ratio.

  17. Metallic nanospheres embedded in nanowires initiated on nanostructures and methods for synthesis thereof

    DOEpatents

    Zaidi, Saleem [Albuquerque, NM; Tringe, Joseph W [Walnut Creek, CA; Vanamu, Ganesh [Sunnyvale, CA; Prinja, Rajiv [Albuquerque, NM

    2012-01-10

    A nanostructure includes a nanowire having metallic spheres formed therein, the spheres being characterized as having at least one of about a uniform diameter and about a uniform spacing there between. A nanostructure in another embodiment includes a substrate having an area with a nanofeature; and a nanowire extending from the nanofeature, the nanowire having metallic spheres formed therein, the spheres being characterized as having at least one of about a uniform diameter and about a uniform spacing there between. A method for forming a nanostructure is also presented. A method for reading and writing data is also presented. A method for preparing nanoparticles is also presented.

  18. Nanostructured optical fiber sensors for breathing airflow monitoring

    NASA Astrophysics Data System (ADS)

    Kang, Y.; Ruan, H.; Mecham, Jeffrey; Wang, Y.; Arregui, Francisco J.; Matias, Ignacio R.; Claus, Richard O.

    2005-05-01

    This paper presents recent progresses in the application of nanostructured optical fiber-based sensors for non-invasive, fast and reliable monitoring of respiratory airflow. Molecular-level self-assembly processing method is used to form multilayered inorganic nanocluster and polymer thin films on the distal ends of optical fibers to form such sensors. In order to optimize sensing performance, recent work has studies the synthesis process and the fundamental mechanisms for the change in optical reflection, specifically caused by exhaled air condensation on the coating surface. The physically small sensors fabricated by varying thin film chemistry, offer a full range of environmental relative humidity sensing from 0% to 100% with response times of microseconds, and mostly important, provide much higher sensitivity to breathing air, over 6 times larger than 100% relative humidity. The sensor performances in comparison with a medical nasal thermistor suggest such a thin film sensor an excellent device for advanced breathing airflow monitoring. All the features are appealing to clinical respiratory diagnosis and related sensor instrumentation design, and in good agreement with our analytical model.

  19. Nature of radio feature formed by re-started jet activity in 3C 84 and its relation with γ-ray emissions

    NASA Astrophysics Data System (ADS)

    Nagai, H.; Chida, H.; Kino, M.; Orienti, M.; D'Ammando, F.; Giovannini, G.; Hiura, K.

    2016-02-01

    Re-started jet activity occurred in the bright nearby radio source 3C 84 in about 2005. The re-started jet is forming a prominent component (namely C3) at the tip of jet. The component has showed an increase in radio flux density for more than 7 years while the radio spectrum remains optically thin. This suggests that the component is the head of a radio lobe including a hotspot where the particle acceleration occurs. Thus, 3C 84 is a unique laboratory to study the physical properties at the very early stage of radio source evolution. Another important aspect is that high energy and very high energy γ-ray emissions are detected from this source. The quest for the site of γ-ray emission is quite important to obtain a better understanding of γ-ray emission mechanisms in radio galaxies. In this paper, we review the observational results from very long baseline interferometry (VLBI) monitoring of 3C 84 reported in series of our previous papers. We argue the nature of re-started jet/radio lobe and its relation with high-energy emission.

  20. Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

    SciTech Connect

    Meisner, Ludmila L.; Semin, Viktor O.; Gudimova, Ekaterina Y.; Neiman, Alexey A. Lotkov, Alexander I.; Ostapenko, Marina G.; Koval, Nikolai N.; Teresov, Anton D.

    2015-10-27

    By transmission electron microscopy method the evolution of structural-phase states on a depth of close to equiatomic NiTi modified layer has been studied. Modification performed by pulse impact on its surface low-energy high-current electron beam (beam energy density 10 J/sm{sup 2}, 10 pulses, pulse duration 50mks). It is established that during the treatment in the layer thickness of 8–10 μm, the melting of primary B2 phase and contained therein as Ti2Ni phase particles occurs. The result is change in the concentration ratio of titanium and nickel in the direction of increasing titanium content, which was confirmed by X-ray analysis in the form of increased unit cell parameter B2 phase. Analysis of the electron diffraction pattern showed that the modified layer is characterized as a highly distorted structure on the basis of bcc lattice. Lattice distortions are maximal near the surface and extends to a depth of melt. In subjacent layer there is gradual decline lattice distortions is observed.

  1. Tissue Engineering Special Feature: A macroporous hydrogel for the coculture of neural progenitor and endothelial cells to form functional vascular networks in vivo

    NASA Astrophysics Data System (ADS)

    Ford, Millicent C.; Bertram, James P.; Royce Hynes, Sara; Michaud, Michael; Li, Qi; Young, Michael; Segal, Steven S.; Madri, Joseph A.; Lavik, Erin B.

    2006-02-01

    A microvascular network is critical for the survival and function of most tissues. We have investigated the potential of neural progenitor cells to augment the formation and stabilization of microvascular networks in a previously uncharacterized three-dimensional macroporous hydrogel and the ability of this engineered system to develop a functional microcirculation in vivo. The hydrogel is synthesized by cross-linking polyethylene glycol with polylysine around a salt-leached polylactic-co-glycolic acid scaffold that is degraded in a sodium hydroxide solution. An open macroporous network is formed that supports the efficient formation of tubular structures by brain endothelial cells. After subcutaneous implantation of hydrogel cocultures in mice, blood flow in new microvessels was apparent at 2 weeks with perfused networks established on the surface of implants at 6 weeks. Compared to endothelial cells cultured alone, cocultures of endothelial cells and neural progenitor cells had a significantly greater density of tubular structures positive for platelet endothelial cell adhesion molecule-1 at the 6-week time point. In implant cross sections, the presence of red blood cells in vessel lumens confirmed a functional microcirculation. These findings indicate that neural progenitor cells promote the formation of endothelial cell tubes in coculture and the development of a functional microcirculation in vivo. We demonstrate a previously undescribed strategy for creating stable microvascular networks to support engineered tissues of desired parenchymal cell origin. microvasculature | neural stem cells | polymer | scaffold

  2. Nanostructures for peroxidases

    PubMed Central

    Carmona-Ribeiro, Ana M.; Prieto, Tatiana; Nantes, Iseli L.

    2015-01-01

    Peroxidases are enzymes catalyzing redox reactions that cleave peroxides. Their active redox centers have heme, cysteine thiols, selenium, manganese, and other chemical moieties. Peroxidases and their mimetic systems have several technological and biomedical applications such as environment protection, energy production, bioremediation, sensors and immunoassays design, and drug delivery devices. The combination of peroxidases or systems with peroxidase-like activity with nanostructures such as nanoparticles, nanotubes, thin films, liposomes, micelles, nanoflowers, nanorods and others is often an efficient strategy to improve catalytic activity, targeting, and reusability. PMID:26389124

  3. Nanoindentation of Carbon Nanostructures.

    PubMed

    Kumar, Dinesh; Singh, Karamjit; Verma, Veena; Bhatti, H S

    2016-06-01

    In the present research paper carbon nanostructures viz. single walled carbon nanotubes, multi-walled carbon nanotubes, single walled carbon nanohorns and graphene nanoplatelets have been synthesized by CVD technique, hydrothermal method, DC arc discharge method in liquid nitrogen and microwave technique respectively. After synthesis 5 mm thick pallets of given nanomaterial are prepared by making a paste in isopropyl alcohol and using polyvinylidene difluoride as a binder and then these pallets were used for nanoindentation measurements. Hardness, reduced modulus, stiffness, contact height and contact area have been measured using nanoindenter.

  4. N-MOSFETs Formed on Solid Phase Epitaxially Grown GeSn Film with Passivation by Oxygen Plasma Featuring High Mobility.

    PubMed

    Fang, Yung-Chin; Chen, Kuen-Yi; Hsieh, Ching-Heng; Su, Chang-Chia; Wu, Yung-Hsien

    2015-12-09

    Solid phase epitaxially grown GeSn was employed as the platform to assess the eligibility of direct O2 plasma treatment on GeSn surface for passivation of GeSn N-MOSFETs. It has been confirmed that O2 plasma treatment forms a GeSnO(x) film on the surface and the GeSnO(x) topped by in situ Al2O3 constitutes the gate stack of GeSn MOS devices. The capability of the surface passivation was evidenced by the low interface trap density (D(it)) of 1.62 × 10(11) cm(-2) eV(-1), which is primarily due to the formation of Ge-O and Sn-O bonds at the surface by high density/reactivity oxygen radicals that effectively suppress dangling bonds and decrease gap states. The good D(it) not only makes tiny frequency dispersion in the characterization of GeSn MOS capacitors, but results in GeSn N-MOSFETs with outstanding peak electron mobility as high as 518 cm(2)/(V s) which outperforms other devices reported in the literature due to reduced undesirable carrier scattering. In addition, the GeSn N-MOSFETs also exhibit promising characteristics in terms of acceptable subthreshold swing of 156 mV/dec and relatively large I(ON)/I(OFF) ratio more than 4 orders. Moreover, the robust reliability in terms small V(t) variation against high field stress attests the feasibility of using the O2 plasma-treated passivation to advanced GeSn technology.

  5. Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica

    NASA Astrophysics Data System (ADS)

    Picard, G.; Royer, A.; Arnaud, L.; Fily, M.

    2014-06-01

    Space-borne passive microwave radiometers are widely used to retrieve information in snowy regions by exploiting the high sensitivity of microwave emission to snow properties. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this paper, we investigate the spatial variations of brightness temperature over a range of a few kilometers in the Dome C area. Using ground-based radiometers towed by a vehicle, we collected brightness temperature at 11, 19 and 37 GHz at horizontal and vertical polarizations along transects with meter resolution. The most remarkable observation was a series of regular undulations of the signal with a significant amplitude reaching 10 K at 37 GHz and a quasi-period of 30-50 m. In contrast, the variability at longer length scales seemed to be weak in the investigated area, and the mean brightness temperature was close to SSM/I and WindSat satellite observations for all the frequencies and polarizations. To establish a link between the snow characteristics and the microwave emission undulations, we collected detailed snow grain size and density profiles at two points where opposite extrema of brightness temperature were observed. Numerical simulations with the DMRT-ML microwave emission model revealed that the difference in density in the upper first meter explained most of the brightness temperature variations. In addition, we found that these variations of density near the surface were linked to snow hardness. Patches of hard snow - probably formed by wind compaction - were clearly visible and covered as much as 39% of the investigated area. Their brightness temperature was higher than in normal areas. This result implies that the microwave emission measured by satellites over Dome C is more complex than expected and very likely depends on

  6. Morphology and thermodynamic characteristics of selenium-containing nanostructures based on polymethacrylic acid

    NASA Astrophysics Data System (ADS)

    Valueva, S. V.; Borovikova, L. N.; Vylegzhanina, M. E.; Sukhanova, T. E.

    2010-09-01

    The morphology and thermodynamic characteristics of nanostructures formed as a result of the reduction of the selenium ion in a selenite-ascorbate redox system in water solutions of polymethacrylic acid were studied by molecular optics and atomic-force microscopy. The dependence of the morphology of the selenium-containing nanostructures on the mass selenium-to-polymer ratio (ν) in solution was determined. It was established that a large number of macromolecules (up to 4300) is adsorbed on the selenium nanoparticles, leading to the formation of nanostructures with super-high molecular mass and an almost spherical form. It was shown that the density of the nanostructures, as calculated on the basis of the experimental data on the size and molecular mass of the nanocomposite, depends substantially on the selenium concentrations in the solution. The thermodynamic state of the solutions of nanostructures is described.

  7. Self-assembled peptide nanostructures for functional materials

    NASA Astrophysics Data System (ADS)

    Sardan Ekiz, Melis; Cinar, Goksu; Aref Khalily, Mohammad; Guler, Mustafa O.

    2016-10-01

    Nature is an important inspirational source for scientists, and presents complex and elegant examples of adaptive and intelligent systems created by self-assembly. Significant effort has been devoted to understanding these sophisticated systems. The self-assembly process enables us to create supramolecular nanostructures with high order and complexity, and peptide-based self-assembling building blocks can serve as suitable platforms to construct nanostructures showing diverse features and applications. In this review, peptide-based supramolecular assemblies will be discussed in terms of their synthesis, design, characterization and application. Peptide nanostructures are categorized based on their chemical and physical properties and will be examined by rationalizing the influence of peptide design on the resulting morphology and the methods employed to characterize these high order complex systems. Moreover, the application of self-assembled peptide nanomaterials as functional materials in information technologies and environmental sciences will be reviewed by providing examples from recently published high-impact studies.

  8. High-throughput drawing and testing of metallic glass nanostructures.

    PubMed

    Hasan, Molla; Kumar, Golden

    2017-03-02

    Thermoplastic embossing of metallic glasses promises direct imprinting of metal nanostructures using templates. However, embossing high-aspect-ratio nanostructures faces unworkable flow resistance due to friction and non-wetting conditions at the template interface. Herein, we show that these inherent challenges of embossing can be reversed by thermoplastic drawing using templates. The flow resistance not only remains independent of wetting but also decreases with increasing feature aspect-ratio. Arrays of assembled nanotips, nanowires, and nanotubes with aspect-ratios exceeding 1000 can be produced through controlled elongation and fracture of metallic glass structures. In contrast to embossing, the drawing approach generates two sets of nanostructures upon final fracture; one set remains anchored to the metallic glass substrate while the second set is assembled on the template. This method can be readily adapted for high-throughput fabrication and testing of nanoscale tensile specimens, enabling rapid screening of size-effects in mechanical behavior.

  9. Nanostructure templating using low temperature atomic layer deposition

    DOEpatents

    Grubbs, Robert K [Albuquerque, NM; Bogart, Gregory R [Corrales, NM; Rogers, John A [Champaign, IL

    2011-12-20

    Methods are described for making nanostructures that are mechanically, chemically and thermally stable at desired elevated temperatures, from nanostructure templates having a stability temperature that is less than the desired elevated temperature. The methods comprise depositing by atomic layer deposition (ALD) structural layers that are stable at the desired elevated temperatures, onto a template employing a graded temperature deposition scheme. At least one structural layer is deposited at an initial temperature that is less than or equal to the stability temperature of the template, and subsequent depositions made at incrementally increased deposition temperatures until the desired elevated temperature stability is achieved. Nanostructure templates include three dimensional (3D) polymeric templates having features on the order of 100 nm fabricated by proximity field nanopatterning (PnP) methods.

  10. Cloning and characterization of four rabbit aldo-keto reductases featuring broad substrate specificity for xenobiotic and endogenous carbonyl compounds: relationship with multiple forms of drug ketone reductases.

    PubMed

    Endo, Satoshi; Matsunaga, Toshiyuki; Arai, Yuki; Ikari, Akira; Tajima, Kazuo; El-Kabbani, Ossama; Yamano, Shigeru; Hara, Akira; Kitade, Yukio

    2014-04-01

    Multiple forms of reductases for several drug ketones were isolated from rabbit liver, but their interrelationship and physiologic roles remain unknown. We isolated cDNAs for four aldo-keto reductases (AKR1C30, AKR1C31, AKR1C32, and AKR1C33), which share high amino acid sequence identity with the partial sequences of two rabbit naloxone reductases. The four recombinant enzymes reduced a variety of carbonyl compounds, including endogenous α-dicarbonyls (e.g., isatin and diacetyl), aldehydes (e.g., farnesal and 4-oxo-2-nonenal), and ketosteroids. They differed in specificity for drug ketones and ketosteroids. Although daunorubicin and befunolol were common substrates of all of the enzymes, AKR enzymes specifically reduced naloxone (AKR1C30, AKR1C32, and AKR1C33), metyrapone (AKR1C32 and AKR1C33), loxoprofen (AKR1C31 and AKR1C32), ketotifen (AKR1C30), and naltrexone and fenofibric acid (AKR1C33). AKR1C30 reduced only 17-keto-5β-androstanes, whereas the other enzymes were active toward 3-, 17-, and 20-ketosteroids, and AKR1C33 further reduced 3-keto groups of bile acids and 7α-hydroxy-5β-cholestanes. In addition, AKR1C30, AKR1C31, AKR1C32, and AKR1C33 were selectively inhibited by carbenoxolone, baccharin, phenolphthalein, and zearalenone, respectively. The mRNAs for the four enzymes were ubiquitously expressed in male rabbit tissues, in which highly expressed tissues were the brain, heart, liver, kidney, intestine, colon, and testis (for AKR1C30 and AKR1C31); brain, heart, liver, kidney, testis, lung, and adrenal gland (for AKR1C32); and liver and intestine (for AKR1C33). Thus, the four enzymes correspond to the multiple drug ketone reductases, and may function in the metabolisms of steroids, isatin and reactive carbonyl compounds, and bile acid synthesis.

  11. Hydrolytic stability of the Si-O-Ti bonds in the chemical assembly of titania nanostructures on silica surfaces

    NASA Astrophysics Data System (ADS)

    Sosnov, Evgeni A.; Malkov, A. A.; Malygin, A. A.

    2010-12-01

    The hydrolytic stability of the Si-O-Ti bonds in titania nanostructures on the surface of silica materials of different genesis is analyzed. The mechanism of hydrolysis is considered and the decisive role of structural and chemical features of silicas in the stability of titania nanostructures on their surface is demonstrated.

  12. Size-dependent optical properties of TiO2 nanostructures

    NASA Astrophysics Data System (ADS)

    Solanki, Vanaraj; Majumder, Subrata; Mishra, Indrani; Joshi, Shalik R.; Kanjilal, Dinakar; Varma, Shikha

    2013-08-01

    The size-dependent optical properties of the nanostructures created on the TiO2(110) surfaces, via low-energy ion-beam sputtering technique, have been investigated here. The crystalline nanostructures have been produced in off-normal geometry. A significant enhancement in UV and visible light absorption has been observed for TiO2 surfaces patterned with nanostructures. Moreover, this enhancement depends on the sizes of the nanostructures. Preferential sputtering of oxygen atoms, during ion beam irradiation, leads to the presence of excess Ti on the surface. Ti-rich zones thus formed can promote nucleation of self-assembled nanostructures on the TiO2(110) surface. These results have been observed in the absence of any dopant. The formation of crystalline TiO2 nanostructures and the development of Ti-rich zones on the surface, after sputtering, are responsible for the enhancement in visible absorbance seen in the present study. Although small-sized (∼10 nm) nanostructures display increased absorbance and a higher bandgap, compared to bulk TiO2, due to quantum effects, much higher absorbance with decreased bandgap is observed from larger-(∼50 nm) sized nanostructures. This enhancement in absorbance is due to the presence of well-developed (200 and 310) crystalline faces in bigger nanostructures.

  13. Intergranular Exchange in Magnetic Nanostructures

    NASA Astrophysics Data System (ADS)

    Skomski, Ralph

    2005-03-01

    Exchange interactions determine not only atomic-scale properties such as the Curie temperature but are also paramount to the realization of mesoscopic magnetism. Nanoscale exchange reflect the relativistic origin of magnetism. On an atomic scale, interatomic exchange tends to be much stronger than magnetic interactions, but the quadratic wave-vector dependence of the exchange energy makes magnetic interactions competitive on a nanoscale. The corresponding characteristic length scale is ao/α = 7.252 nm, where ao is the Bohr radius and α = 1/137 is Sommerfeld's fine structure constant. In homogeneous solids, the competing relativistic and nonrelativistic interactions determine, for example, the thickness of domain walls. In nanostructures, the situation is more complex, because mesoscopic and atomic exchange effects interfere with structural length scales. This is important in many areas of magnetism, such as permanent magnetism, soft magnetism, spin electronics, and magnetic recording. (For a recent review, see Skomski, J. Phys. CM, vol. 15, 2003, p. R841.) From an atomic point of view, local magnetic moments embedded in an itinerant electron gas are coupled by RKKY-type interactions, whose oscillatory period is determined by the Fermi wave vector kF. First, RKKY interaction between embedded clusters or particles do not average to zero but actually increase with particle size. Second, the low carrier densities of semimetals and semiconductors yield small Fermi wave vectors and nanoscale oscillation periodicities. From a mesoscopic point of view, traditional random-anisotropy scaling amounts to a dimensionless coupling constant A/K1R^2, but this expression fails to account for important real-structure features. For example, grain boundaries with reduced interatomic exchange give rise to a quasi-discontinuity of the magnetization, create a magnetization perturbation that extends far into the bulk, and modify scaling relations for the coercivity and other quantities

  14. Mesoporous SnO2 nanostructures of ultrahigh surface areas by novel anodization.

    PubMed

    Bian, Haidong; Tian, Yayuan; Lee, Chris; Yuen, Muk Fung; Zhang, WenJun; Li, Yang Yang

    2016-10-04

    Here we report a novel type of hierarchical mesoporous SnO2 nanostructures fabricated by a facile anodization method in a novel electrolyte system (an ethylene glycol solution of H2C2O4/NH4F) followed by thermal annealing at a low temperature. The SnO2 nanostructures thus obtained feature highly porous nanosheets with mesoporous pores well below 10 nm, enabling a remarkably high surface area of 202.8 m2/g which represents one of the highest values reported to date on SnO2 nanostructures. The formation of this novel type of SnO2 nanostructures is ascribed to an interesting self-assembly mechanism of the anodic tin oxalate, which was found to be heavily impacted by the anodization voltage and water content in the electrolyte. The electrochemical measurements of the mesoporous SnO2 nanostructures indicate their promising applications as lithium-ion battery and supercapacitor electrode materials.

  15. Disparities in correlating microstructural to nanostructural preservation of dinosaur femoral bones

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Kyun; Kwon, Yong-Eun; Lee, Sang-Gil; Lee, Ji-Hyun; Kim, Jin-Gyu; Huh, Min; Lee, Eunji; Kim, Youn-Joong

    2017-03-01

    Osteohistological researches on dinosaurs are well documented, but descriptions of direct correlations between the bone microstructure and corresponding nanostructure are currently lacking. By applying correlative microscopy, we aimed to verify that well-preserved osteohistological features correlate with pristine fossil bone nanostructures from the femoral bones of Koreanosaurus boseongensis. The quality of nanostructural preservation was evaluated based on the preferred orientation level of apatite crystals obtained from selected area electron diffraction (SAED) patterns and by measuring the “arcs” from the {100} and {002} diffraction rings. Unlike our expectations, our results revealed that well-preserved microstructures do not guarantee pristine nanostructures and vice versa. Structural preservation of bone from macro- to nanoscale primarily depends on original bioapatite density, and subsequent taphonomical factors such as effects from burial, pressure, influx of external elements and the rate of diagenetic alteration of apatite crystals. Our findings suggest that the efficient application of SAED analysis opens the opportunity for comprehensive nanostructural investigations of bone.

  16. Magnetic Properties of Nanostructures

    NASA Astrophysics Data System (ADS)

    Ciraldo, John

    2007-10-01

    The recent development of the superlattice nanowire pattern transfer (SNAP) technique has enabled the fabrication of complex molecular-electronic circuits at unprecedented densities. In this project, we explore the possibility of extending this technique to generate comparably dense arrays of nanoscale giant magnetoresistive (GMR) and tunneling magnetoresistive (TMR) devices. My primary contribution to this project has focused on using a vibrating sample magnetometer (VSM), as well as a superconducting interference device (SQUID) magnetometer to monitor the magnetic properties of the devices as they are processed from thin 2D films into nanostructure arrays. This investigation allows us to investigate both fundamental and technological aspects of the nanopatterning process. For example, the effects of changing surface to volume ratios on the ferromagnetic exchange interaction and the role of various patterning techniques in determining surface chemistry and oxidation of the final nanostructures, respectively. Additionally I have worked on simulations of the materials using NIST's OOMF program, allowing me to compare actual results with theoretical expectations. I am also designing a magneto-optical Kerr effect (MOKE) detector, which will allow faster approximations of magnetic behavior.

  17. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    NASA Astrophysics Data System (ADS)

    Pruna, R.; Palacio, F.; López, M.; Pérez, J.; Mir, M.; Blázquez, O.; Hernández, S.; Garrido, B.

    2016-08-01

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  18. Ion-beam assisted laser fabrication of sensing plasmonic nanostructures

    PubMed Central

    Kuchmizhak, Aleksandr; Gurbatov, Stanislav; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

    2016-01-01

    Simple high-performance, two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique, a thin noble-metal film on a dielectric substrate is irradiated by a single tightly focused nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar+) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar+-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depend on the laser pulse energy and metal film thickness, while subsequent Ar+-ion polishing enables to vary height of the resulting nanostructures. Plasmonic properties of the fabricated nanostructures were characterized by dark-field micro-spectroscopy, Raman and photoluminescence measurements performed on single nanofeatures, as well as by supporting numerical calculations of the related electromagnetic near-fields and Purcell factors. The developed simple two-stage technique represents a new step towards direct large-scale laser-induced fabrication of highly ordered arrays of complex plasmonic nanostructures. PMID:26776569

  19. Ion-beam assisted laser fabrication of sensing plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Kuchmizhak, Aleksandr; Gurbatov, Stanislav; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

    2016-01-01

    Simple high-performance, two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique, a thin noble-metal film on a dielectric substrate is irradiated by a single tightly focused nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar+) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar+-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depend on the laser pulse energy and metal film thickness, while subsequent Ar+-ion polishing enables to vary height of the resulting nanostructures. Plasmonic properties of the fabricated nanostructures were characterized by dark-field micro-spectroscopy, Raman and photoluminescence measurements performed on single nanofeatures, as well as by supporting numerical calculations of the related electromagnetic near-fields and Purcell factors. The developed simple two-stage technique represents a new step towards direct large-scale laser-induced fabrication of highly ordered arrays of complex plasmonic nanostructures.

  20. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    SciTech Connect

    Pruna, R. Palacio, F.; López, M.; Mir, M.; Blázquez, O.; Hernández, S.; Garrido, B.

    2016-08-08

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  1. Ion-beam assisted laser fabrication of sensing plasmonic nanostructures.

    PubMed

    Kuchmizhak, Aleksandr; Gurbatov, Stanislav; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

    2016-01-18

    Simple high-performance, two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique, a thin noble-metal film on a dielectric substrate is irradiated by a single tightly focused nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar(+)) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar(+)-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depend on the laser pulse energy and metal film thickness, while subsequent Ar(+)-ion polishing enables to vary height of the resulting nanostructures. Plasmonic properties of the fabricated nanostructures were characterized by dark-field micro-spectroscopy, Raman and photoluminescence measurements performed on single nanofeatures, as well as by supporting numerical calculations of the related electromagnetic near-fields and Purcell factors. The developed simple two-stage technique represents a new step towards direct large-scale laser-induced fabrication of highly ordered arrays of complex plasmonic nanostructures.

  2. Rapid synthesis of flower-like ZnO nanostructures.

    PubMed

    Movahedi, Maryam; Mahjoub, Ali Reza; Yavari, Issa; Kowsari, Elaheh

    2010-09-01

    Flower-like ZnO nanostructures were prepared via microwave assisted heating in the presence and absence of ionic liquid (IL). X-ray diffraction analysis (XRD), Scanning electron microscopy SEM and room temperature photoluminescence (PL) spectra have been employed for characterization of the products. The SEM image illustrates the surface of flower-like ZnO prepared in the presence of IL is not smooth and consists of nanoparticles with grain size of about 48 nm. PL spectra of flower-like ZnO in absence and presence IL reveal similar photoluminescence features: a strong UV, weak blue and green-yellow emissions peak at a bout 393 nm, 448 nm and 583 nm respectively. The strong UV photoluminescence and the weak green emission indicate the good crystallization quality of the flower-like nanostructure. The results show that imidazolium-based IL can be used as template for achieving very high level control over the size and shape of nanostructures. The approach developed in this work can potentially be used as a viable method for making various other uniform nanostructures in the presence of IL. This method is simple, fast, low-cost and suitable for large-scale production of ZnO nanostructures.

  3. Making nanostructured pyrotechnics in a beaker

    SciTech Connect

    Gash, A E; Simpson, R L; Tillotson, T M; Satcher, J H; Hrubesh, L W

    2000-04-10

    Controlling composition at the nanometer scale is well known to alter material properties in sometimes highly desirable and dramatic ways. In the field of energetic materials component distributions, particle size, and morphology, effect both sensitivity and reactivity performance. To date nanostructured energetic materials are largely unknowns with the exception of nanometer-sized reactive powders now being produced at a number of laboratories. We have invented a new method of making nanostructured energetic materials, specifically explosives, propellants, and pyrotechnics, using sol-gel chemistry. The ease of this synthetic approach along with the inexpensive, stable, and benign nature of the metal precursors and solvents permit large-scale syntheses to be carried out. This approach can be accomplished using low cost processing methods. We will describe here, for the first time, this new synthetic route for producing metal-oxide-based pyrotechnics. The procedure employs the use of stable and inexpensive hydrated-metal inorganic salts and environmentally friendly solvents such as water and ethanol. The synthesis is straightforward and involves the dissolution the metal salt in a solvent followed by the addition of an epoxide, which induces gel formation in a timely manner. Experimental evidence suggests that the epoxide acts as an irreversible proton scavenger that induces the hydrated-metal species to undergo hydrolysis and condensation to form a sol that undergoes. further condensation to form a metal-oxide nanostructured gel. Both critical point and atmospheric drying have been employed to produce monolithic aerogels and xerogels, respectively. Using this method we have synthesized metal-oxide nanostructured materials using Fe{sup 3+}, Cr{sup 3+}, Al{sup 3+}, Ga{sup 3+}, In{sup 3+}, Hf{sup 4+}, Sn{sup 4+} and Zr{sup 4+} inorganic salts. Using related methods we have made nanostructured oxides of Mo, Ti, V, Co, Ni, Cu, Y , Ta, W, Pb, B, Pr, Er, Nd and Si. These

  4. EDITORIAL: Nanostructured solar cells Nanostructured solar cells

    NASA Astrophysics Data System (ADS)

    Greenham, Neil C.; Grätzel, Michael

    2008-10-01

    Conversion into electrical power of even a small fraction of the solar radiation incident on the Earth's surface has the potential to satisfy the world's energy demands without generating CO2 emissions. Current photovoltaic technology is not yet fulfilling this promise, largely due to the high cost of the electricity produced. Although the challenges of storage and distribution should not be underestimated, a major bottleneck lies in the photovoltaic devices themselves. Improving efficiency is part of the solution, but diminishing returns in that area mean that reducing the manufacturing cost is absolutely vital, whilst still retaining good efficiencies and device lifetimes. Solution-processible materials, e.g. organic molecules, conjugated polymers and semiconductor nanoparticles, offer new routes to the low-cost production of solar cells. The challenge here is that absorbing light in an organic material produces a coulombically bound exciton that requires dissociation at a donor-acceptor heterojunction. A thickness of at least 100 nm is required to absorb the incident light, but excitons only diffuse a few nanometres before decaying. The problem is therefore intrinsically at the nano-scale: we need composite devices with a large area of internal donor-acceptor interface, but where each carrier has a pathway to the respective electrode. Dye-sensitized and bulk heterojunction cells have nanostructures which approach this challenge in different ways, and leading research in this area is described in many of the articles in this special issue. This issue is not restricted to organic or dye-sensitized photovoltaics, since nanotechnology can also play an important role in devices based on more conventional inorganic materials. In these materials, the electronic properties can be controlled, tuned and in some cases completely changed by nanoscale confinement. Also, the techniques of nanoscience are the natural ones for investigating the localized states, particularly at

  5. Growth and reactions of SiOx/Si nanostructures on surface-templated molecule corrals.

    PubMed

    Liu, Yi; Zhang, Zhanping; Wells, Matthew C; Beebe, Thomas P

    2005-09-13

    Surface-templated nanostructures on the highly oriented pyrolytic graphite (HOPG) basal plane were created by controlled Cs+- or Ga+)ion bombardment, followed by subsequent oxidation at high temperature, forming molecule corrals. The corrals were then used for template growth of SiOx/Si nanostructures. We demonstrate here that, for SiOx/Si nanostructures formed in controlled molecule corrals, the amount of silicon deposited on the surface is directly correlated with the corral density, making it possible to generate patterned SiOx/Si nanostructures on HOPG. Since the size, depth, position, and surface density of the nanostructures can be controlled on the HOPG, it is possible to produce surfaces with patterned or gradient functionalities for applications in fields such as biosensors, microelectronics, and biomaterials (e.g., neuron pathfinding). If desired, the SiOx structures can be reduced in size by etching in dilute HF, and further oxidation of the nanostructures is slow enough to provide plenty of time to functionalize them using ambient and solution reactions and to perform surface analysis. Organosilane monolayers on surface-templated SiOx/Si nanostructures were examined by X-ray photoelectron spectroscopy, time-of-flight secondary ion mas spectrometry, and atomic force microscopy. Silanes with long alkyl chains such as n-octadecyltrichlorosilane (C18) were found to both react on SiOx/Si nanostructures and to condense on the HOPG basal plane. Shorter-chain silanes, such as 11-bromoundicyltrimethoxysilane (C11) and 3-mercaptopropyltrimethoxysilane (C3) were found to react preferentially with SiOx/Si nanostructures, not HOPG. The SiOx/Si nanostructures were also found to be stable toward multiple chemical reactions. Selective modification of SiOx/Si nanostructures on the HOPG basal plane is thus achievable.

  6. Lithographically-directed self-assembly of nanostructures

    SciTech Connect

    Liddle, J. Alexander; Cui, Yi; Alivisatos, Paul

    2004-09-21

    The combination of lithography and self-assembly provides apowerful means of organizing solution-synthesized nanostructures for awide variety of applications. We have developed a fluidic assembly methodthat relies on the local pinning of a moving liquid contact line bylithographically produced topographic features to concentratenanoparticles at those features. The final stages of the assembly processare controlled first by long-range immersion capillary forces and then bythe short-range electrostatic and Van der Waal's interactions. We havesuccessfully assembled nanoparticles from 50 nm to 2 nm in size usingthis technique and have also demonstrated the controlled positioning ofmore complex nanotetrapod structures. We have used this process toassemble Au nanoparticles into pre-patterned electrode structures andhave performed preliminary electrical characterization of the devices soformed. The fluidic assembly method is capable of very high yield, interms of positioning nanostructures at each lithographically-definedlocation, and of excellent specificity, with essentially no particledeposition between features.

  7. Superhydrophobic nature of nanostructures on an indigenous Australian eucalyptus plant and its potential application

    PubMed Central

    Poinern, Gérrard Eddy Jai; Le, Xuan Thi; Fawcett, Derek

    2011-01-01

    In this preliminary study, the morphology and nanostructured features formed by the epicuticular waxes of the mottlecah (Eucalyptus macrocarpa) leaf were investigated and quantified. The surface features formed by the waxes give the leaf remarkable wetting and self-cleaning properties that enhance the plant’s survival in an arid climate. This paper also provides experimental evidence of the self-assembly properties of the epicuticular waxes. Analysis of the water contact angle measurements gave a mean static contact angle of 162.00 ± 6.10 degrees, which clearly indicated that the mottlecah’s leaf surface was superhydrophobic. Detailed field emission scanning electron microscopy examination revealed that the surface was covered by bumps approximately 20 μm in diameter and regularly spaced at a distance of around 26 μm. The bumps are capped by nanotubules/pillars with an average diameter of 280 nm at the tips. Self-cleaning experiments indicated that the mottlecah’s leaf could be effectively cleaned by a fine spray of water droplets that rolled over the surface picking up contaminants. Field emission scanning electron microscopy investigation of extracted epicuticular waxes revealed that the waxes were capable of self-reassembly and formed features similar to those of the original leaf surface. Furthermore, also reported is a simple technique for surface treating one side of a planar surface to produce a superhydrophobic surface that can be used as a planar floatation platform for microdevices. PMID:24198490

  8. Superhydrophobic nature of nanostructures on an indigenous Australian eucalyptus plant and its potential application.

    PubMed

    Poinern, Gérrard Eddy Jai; Le, Xuan Thi; Fawcett, Derek

    2011-01-01

    In this preliminary study, the morphology and nanostructured features formed by the epicuticular waxes of the mottlecah (Eucalyptus macrocarpa) leaf were investigated and quantified. The surface features formed by the waxes give the leaf remarkable wetting and self-cleaning properties that enhance the plant's survival in an arid climate. This paper also provides experimental evidence of the self-assembly properties of the epicuticular waxes. Analysis of the water contact angle measurements gave a mean static contact angle of 162.00 ± 6.10 degrees, which clearly indicated that the mottlecah's leaf surface was superhydrophobic. Detailed field emission scanning electron microscopy examination revealed that the surface was covered by bumps approximately 20 μm in diameter and regularly spaced at a distance of around 26 μm. The bumps are capped by nanotubules/pillars with an average diameter of 280 nm at the tips. Self-cleaning experiments indicated that the mottlecah's leaf could be effectively cleaned by a fine spray of water droplets that rolled over the surface picking up contaminants. Field emission scanning electron microscopy investigation of extracted epicuticular waxes revealed that the waxes were capable of self-reassembly and formed features similar to those of the original leaf surface. Furthermore, also reported is a simple technique for surface treating one side of a planar surface to produce a superhydrophobic surface that can be used as a planar floatation platform for microdevices.

  9. Lithium insertion in nanostructured TiO(2)(B) architectures.

    PubMed

    Dylla, Anthony G; Henkelman, Graeme; Stevenson, Keith J

    2013-05-21

    Electric vehicles and grid storage devices have potentialto become feasible alternatives to current technology, but only if scientists can develop energy storage materials that offer high capacity and high rate capabilities. Chemists have studied anatase, rutile, brookite and TiO2(B) (bronze) in both bulk and nanostructured forms as potential Li-ion battery anodes. In most cases, the specific capacity and rate of lithiation and delithiation increases as the materials are nanostructured. Scientists have explained these enhancements in terms of higher surface areas, shorter Li(+) diffusion paths and different surface energies for nanostructured materials allowing for more facile lithiation and delithiation. Of the most studied polymorphs, nanostructured TiO2(B) has the highest capacity with promising high rate capabilities. TiO2(B) is able to accommodate 1 Li(+) per Ti, giving a capacity of 335 mAh/g for nanotubular and nanoparticulate TiO2(B). The TiO2(B) polymorph, discovered in 1980 by Marchand and co-workers, has been the focus of many recent studies regarding high power and high capacity anode materials with potential applications for electric vehicles and grid storage. This is due to the material's stability over multiple cycles, safer lithiation potential relative to graphite, reasonable capacity, high rate capability, nontoxicity, and low cost (Bruce, P. G.; Scrosati, B.; Tarascon, J.-M. Nanomaterials for Rechargeable Lithium Batteries. Angew. Chem., Int. Ed.2008, 47, 2930-2946). One of the most interesting properties of TiO2(B) is that both bulk and nanostructured forms lithiate and delithiate through a surface redox or pseudocapacitive charging mechanism, giving rise to stable high rate charge/discharge capabilities in the case of nanostructured TiO2(B). When other polymorphs of TiO2 are nanostructured, they still mainly intercalate lithium through a bulk diffusion-controlled mechanism. TiO2(B) has a unique open crystal structure and low energy Li

  10. Silk fibroin nanostructured materials for biomedical applications

    NASA Astrophysics Data System (ADS)

    Mitropoulos, Alexander N.

    Nanostructured biopolymers have proven to be promising to develop novel biomedical applications where forming structures at the nanoscale normally occurs by self-assembly. However, synthesizing these structures can also occur by inducing materials to transition into other forms by adding chemical cross-linkers, changing pH, or changing ionic composition. Understanding the generation of nanostructures in fluid environments, such as liquid organic solvents or supercritical fluids, has not been thoroughly examined, particularly those that are based on protein-based block-copolymers. Here, we examine the transformation of reconstituted silk fibroin, which has emerged as a promising biopolymer due to its biocompatibility, biodegradability, and ease of functionalization, into submicron spheres and gel networks which offer applications in tissue engineering and advanced sensors. Two types of gel networks, hydrogels and aerogels, have small pores and large surface areas that are defined by their structure. We design and analyze silk nanoparticle formation using a microfluidic device while offering an application for drug delivery. Additionally, we provide a model and characterize hydrogel formation from micelles to nanoparticles, while investigating cellular response to the hydrogel in an in vitro cell culture model. Lastly, we provide a second model of nanofiber formation during near-critical and supercritical drying and characterize the silk fibroin properties at different drying pressures which, when acting as a stabilizing matrix, shows to improve the activity of entrapped enzymes dried at different pressures. This work has created new nanostructured silk fibroin forms to benefit biomedical applications that could be applied to other fibrous proteins.

  11. The morphological and optical characteristics of femtosecond laser-induced large-area micro/nanostructures on GaAs, Si, and brass.

    PubMed

    Huang, Min; Zhao, Fuli; Cheng, Ya; Xu, Ningsheng; Xu, Zhizhan

    2010-11-08

    We systematically study the morphological and optical characteristics of the large-area micro/nanostructures produced by femtosecond laser irradiation on GaAs, Si, and brass. The experimental results demonstrate that along with the increase of laser fluence, significant changes in the surface morphology can be observed, and the most prominent phenomenon is the enlarging of the feature size of formed structures. Interestingly, by the fourier analysis of the treated areas, a peculiar phenomenon can be revealed: as laser fluence increases, the spatial frequencies of the structures change following a specific law--the allowed main frequencies are discrete, and appear to be a sequence of 2f, f, f/2, f/4, and f/8 (f is the fundamental frequency corresponding to the near-subwavelength ripples). In our opinion, the new frequency components of f/2, f/4, and f/8 originate in the 2-order, 4-order, and 8-order grating coupling. The law can offer us new insights for the evolving mechanisms of a variety of laser-induced micro/nanostructures in different scales. Furthermore, the optical characteristics of the treated surface are strongly dependent on the morphological characteristics that are mainly determined by laser fluence, such as the feature size of the micro/nanostructures, the topology of the surface morphology, the surface roughness, and the irregular degree of the formed structures. In general, as laser fluence increases in a moderate range, the specular reflectance of the structured surface would be significantly reduced. However, if laser fluence is excessive, the anti-specular-reflection effect would be much weakened. In ideal laser fluence, the micro/nanostructures produced by the near-infrared laser can achieve an ultra-low specular reflectance in the visible and near-infrared spectral region, which exhibits an attracting application prospect in the field of utilizing solar energy.

  12. Periodic nanostructural materials for nanoplasmonics

    NASA Astrophysics Data System (ADS)

    Choi, Dukhyun

    2017-02-01

    Nanoscale periodic material design and fabrication are essentially fundamental requirement for basic scientific researches and industrial applications of nanoscience and engineering. Innovative, effective, reproducible, large-area uniform, tunable and robust nanostructure/material syntheses are still challenging. Here, I would like to introduce the novel periodic nanostructural materials particularly with uniformly ordered nanoporous or nanoflower structures, which are fabricated by simple, cost-effective, and high-throughput wet chemical methods. I also report large-area periodic plasmonic nanostructures based on template-based nanolithography. The surface morphology and optical properties are characterized by SEM and UV-vis. spectroscopy. Furthermore, their enhancement factor is evaluated by using SERS signals.

  13. Mechanical design of DNA nanostructures.

    PubMed

    Castro, Carlos E; Su, Hai-Jun; Marras, Alexander E; Zhou, Lifeng; Johnson, Joshua

    2015-04-14

    Structural DNA nanotechnology is a rapidly emerging field that has demonstrated great potential for applications such as single molecule sensing, drug delivery, and templating molecular components. As the applications of DNA nanotechnology expand, a consideration of their mechanical behavior is becoming essential to understand how these structures will respond to physical interactions. This review considers three major avenues of recent progress in this area: (1) measuring and designing mechanical properties of DNA nanostructures, (2) designing complex nanostructures based on imposed mechanical stresses, and (3) designing and controlling structurally dynamic nanostructures. This work has laid the foundation for mechanically active nanomachines that can generate, transmit, and respond to physical cues in molecular systems.

  14. Electronic Properties of Novel Nanostructures

    NASA Astrophysics Data System (ADS)

    Kuzmany, Hans; Fink, Jörg; Mehring, Michael; Roth, Siegmar

    The 19th Winterschool focused mainly on new nanostructured materials, with data presented on functionalized fullerenes and carbon nanotubes, filled and double-wall nanotubes, non-carbon nanotubes, such as BN and MoS2 tubes, and other nanostructures. The direction of nanoelectronics research was explored in depth, and advancements in composite technology and novel applications for nanotubes were discussed. Importantly, participants were updated on the theoretical and experimental determinations of structural and electronic properties as well as on characterization methods for molecular nanostructures.

  15. Structural differences between capped GaSb nanostructures grown by Stranski-Krastanov and droplet epitaxy growth modes

    NASA Astrophysics Data System (ADS)

    DeJarld, Matt; Yan, Lifan; Luengo-Kovac, Marta; Sih, Vanessa; Millunchick, Joanna

    2017-01-01

    Droplet epitaxy (DE) has emerged as an alternative to Stranski-Krastanov (SK) as a method for epitaxial nanostructure formation. We find significant structural differences of similar sized nanostructures embedded in GaAs between the two methods. Atomic force microscopy and atom probe tomography measurements reveal that uncapped and capped SK structures resemble each other. However, the DE nanostructures appear as rings topographically but are quantum dots compositionally. A GaSb wetting layer is present regardless of the growth method and shares a nearly identical Sb concentration profile. DE nanostructures are shown to have a lower Sb concentration, and transmission electron microscopy measurements reveal that they produce less strain on the capping layer. Despite significant structural differences, SK and DE nanostructures exhibit the same photoluminescence response, suggesting that the emission is from a shared feature such as the wetting layer, rather than the nanostructures.

  16. Numerical Simulation of Nanostructure Growth

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    Nanoscale structures, such as nanowires and carbon nanotubes (CNTs), are often grown in gaseous or plasma environments. Successful growth of these structures is defined by achieving a specified crystallinity or chirality, size or diameter, alignment, etc., which in turn depend on gas mixture ratios. pressure, flow rate, substrate temperature, and other operating conditions. To date, there has not been a rigorous growth model that addresses the specific concerns of crystalline nanowire growth, while demonstrating the correct trends of the processing conditions on growth rates. Most crystal growth models are based on the Burton, Cabrera, and Frank (BCF) method, where adatoms are incorporated into a growing crystal at surface steps or spirals. When the supersaturation of the vapor is high, islands nucleate to form steps, and these steps subsequently spread (grow). The overall bulk growth rate is determined by solving for the evolving motion of the steps. Our approach is to use a phase field model to simulate the growth of finite sized nanowire crystals, linking the free energy equation with the diffusion equation of the adatoms. The phase field method solves for an order parameter that defines the evolving steps in a concentration field. This eliminates the need for explicit front tracking/location, or complicated shadowing routines, both of which can be computationally expensive, particularly in higher dimensions. We will present results demonstrating the effect of process conditions, such as substrate temperature, vapor supersaturation, etc. on the evolving morphologies and overall growth rates of the nanostructures.

  17. Numerical Simulation of Nanostructure Growth

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    Nanoscale structures, such as nanowires and carbon nanotubes (CNTs), are often grown in gaseous or plasma environments. Successful growth of these structures is defined by achieving a specified crystallinity or chirality, size or diameter, alignment, etc., which in turn depend on gas mixture ratios. pressure, flow rate, substrate temperature, and other operating conditions. To date, there has not been a rigorous growth model that addresses the specific concerns of crystalline nanowire growth, while demonstrating the correct trends of the processing conditions on growth rates. Most crystal growth models are based on the Burton, Cabrera, and Frank (BCF) method, where adatoms are incorporated into a growing crystal at surface steps or spirals. When the supersaturation of the vapor is high, islands nucleate to form steps, and these steps subsequently spread (grow). The overall bulk growth rate is determined by solving for the evolving motion of the steps. Our approach is to use a phase field model to simulate the growth of finite sized nanowire crystals, linking the free energy equation with the diffusion equation of the adatoms. The phase field method solves for an order parameter that defines the evolving steps in a concentration field. This eliminates the need for explicit front tracking/location, or complicated shadowing routines, both of which can be computationally expensive, particularly in higher dimensions. We will present results demonstrating the effect of process conditions, such as substrate temperature, vapor supersaturation, etc. on the evolving morphologies and overall growth rates of the nanostructures.

  18. Method of Making Large Area Nanostructures

    NASA Technical Reports Server (NTRS)

    Marks, Alvin M.

    1995-01-01

    A method which enables the high speed formation of nanostructures on large area surfaces is described. The method uses a super sub-micron beam writer (Supersebter). The Supersebter uses a large area multi-electrode (Spindt type emitter source) to produce multiple electron beams simultaneously scanned to form a pattern on a surface in an electron beam writer. A 100,000 x 100,000 array of electron point sources, demagnified in a long electron beam writer to simultaneously produce 10 billion nano-patterns on a 1 meter squared surface by multi-electron beam impact on a 1 cm squared surface of an insulating material is proposed.

  19. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    SciTech Connect

    Black, Marcie

    2014-10-30

    This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

  20. Nanostructured Magnesium Hydride for Reversible Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    de Rango, P.; Chaise, A.; Fruchart, D.; Miraglia, S.; Marty, Ph.

    2013-05-01

    The aim of this work was to develop suitable materials to store hydrogen in a solid state. A systematic investigation of the co-milling process of magnesium hydride with a transition metal was undertaken in order to produce nanostructured and highly reactive powders. The initiating role of the transition metal was evidenced by in situ neutron diffraction experiments. High performances in terms of thermal and mechanical behavior were achieved introducing expanded graphite and compacting the mixture to form composite materials. Absorption and desorption kinetics have been measured versus temperature and H2 pressure.

  1. Effective elastic properties of two dimensional multiplanar hexagonal nanostructures

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, T.; Mahata, A.; Adhikari, S.; Asle Zaeem, M.

    2017-06-01

    A generalized analytical approach is presented to derive closed-form formulae for the elastic moduli of hexagonal multiplanar nano-structures. Hexagonal nano-structural forms are common for various materials. Four different classes of materials (single layer) from a structural point of view are proposed to demonstrate the validity and prospective application of the developed formulae. For example, graphene, an allotrope of carbon, consists of only carbon atoms to form a honeycomb like hexagonal lattice in a single plane, while hexagonal boron nitride (hBN) consists of boron and nitrogen atoms to form the hexagonal lattice in a single plane. Unlike graphene and hBN, there are plenty of other materials with hexagonal nano-structures that have the atoms placed in multiple planes such as stanene (consists of only Sn atoms) and molybdenum disulfide (consists of two different atoms: Mo and S). The physics based high-fidelity analytical model developed in this article are capable of obtaining the elastic properties in a computationally efficient manner for wide range of such materials with hexagonal nano-structures that are broadly classified in four classes from structural viewpoint. Results are provided for materials belonging to all the four classes, wherein a good agreement between the elastic moduli obtained using the proposed formulae and available scientific literature is observed.

  2. Ultrafast Dynamics of Heat Generation in Plasmonic Nanostructures

    DTIC Science & Technology

    2014-10-09

    Biosensing, optical forces, optical nonlinearities, quantum electrodynamics , surface enhanced Raman spectroscopy 16. SECURITY CLASSIFICATION OF: 17...nanostructures can form resonances for the enhancement of electromagnetic intensity, resulting in numerous applications including quantum ... electrodynamics , optical nonlinearities, optical forces, surface enhanced Raman spectroscopy and biosensing. 2 Introduction The objective of this project is

  3. Electronic properties of complex nanostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Zhen

    Nanostructured materials have brought an unprecedented opportunity for advancement in many fields of human endeavor and in applications. Nanostructures are a new research field which may revolutionize people's everyday life. In the Thesis, I have used theoretical methods including density functional theory (DFT), molecular dynamic simulations (MD) and tight-binding methods to explore the structural, mechanical and electronic properties of various nanomaterials. In all this, I also paid attention to potential applications of these findings. First, I will briefly introduce the scientific background of this Thesis, including the motivation for the study of a boron enriched aluminum surface, novel carbon foam structures and my research interest in 2D electronics. Then I will review the computational techniques I used in the study, mostly DFT methods. In Chapter 3, I introduce an effective way to enhance surface hardness of aluminum by boron nanoparticle implantation. Using boron dimers to represent the nanoparticles, the process of boron implantation is modeled in a molecular dynamics simulation of bombarding the aluminum surface by energetic B 2 molecules. Possible metastable structures of boron-coated aluminum surface are identified. Within these structures, I find that boron atoms prefer to stay in the subsurface region of aluminum. By modeling the Rockwell indentation process, boron enriched aluminum surface is found to be harder than the pristine aluminum surface by at least 15%. In Chapter 4, I discuss novel carbon structures, including 3D carbon foam and related 2D slab structures. Carbon foam contains both sp 2 and sp3 hybridized carbon atoms. It forms a 3D honeycomb lattice with a comparable stability to fullerenes, suggesting possible existence of such carbon foam structures. Although the bulk 3D foam structure is semiconducting, an sp2 terminated carbon surface could maintain a conducting channel even when passivated by hydrogen. To promote the experimental

  4. Composite, nanostructured, super-hydrophobic material

    DOEpatents

    D'Urso, Brian R.; Simpson, John T.

    2007-08-21

    A hydrophobic disordered composite material having a protrusive surface feature includes a recessive phase and a protrusive phase, the recessive phase having a higher susceptibility to a preselected etchant than the protrusive phase, the composite material having an etched surface wherein the protrusive phase protrudes from the surface to form a protrusive surface feature, the protrusive feature being hydrophobic.

  5. Rapid Solid-State Metathesis Routes to Nanostructured Silicon-Germainum

    NASA Technical Reports Server (NTRS)

    Kaner, Richard B. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor); Rodriguez, Marc (Inventor)

    2014-01-01

    Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

  6. Bioscaffolds for metal nanostructures

    NASA Astrophysics Data System (ADS)

    Radloff, Corey J.; Vaia, Richard A.; Brunton, Jason; Ward, Vernon; Kalmakoff, James; Dokland, Terge

    2004-10-01

    The use of virus nanoparticles, specifically Chilo and Wiseana Iridovirus, as core substrates in the fabrication of metallodielectric, plasmonic nanostructures is discussed. A gold shell is assembled around the viral core by attaching small, 2 - 5 nm, gold nanoparticles to the virus surface by means of inherent chemical functionality found within the protein cage structure of the viral capsid. These gold nanoparticles act as nucleation sites for electroless deposition of gold ions from solution. The density of the gold nucleation sites on the virus was maximized by reducing the repulsive forces between the gold particles, which was accompolished by controlling the ionic strength of the nanoparticle solution. UV/Vis spectroscopy and transmission electron microscopy were used to verify creation of the virus-Au particles. The optical extinction spectra of the metallo-viral complex were compared to Mie scattering theory and found to be in quantitative agreement.

  7. Alternative nanostructures for thermophones

    NASA Astrophysics Data System (ADS)

    Mayo, Nathanael; Aliev, Ali; Baughman, Ray

    2015-03-01

    There is a large promise for thermophones in high power sonar arrays, flexible loudspeakers, and noise cancellation devices. So far, freestanding aerogel-like carbon nanotube sheets demonstrate the best performance as a thermoacoustic heat source. However, the limited accessibility of large size freestanding carbon nanotube sheets and other even more exotic materials published recently, hampers the field. We present here new alternative materials for a thermoacoustic heat source with high energy conversion efficiency, additional functionalities, environmentally friendly and cost effective production technologies. We discuss the thermoacoustic performance of alternative nanoscale materials and compare their spectral and power dependencies of sound pressure in air. The study presented here focuses on engineering thermal gradients in the vicinity of nanostructures and subsequent heat dissipation processes from the interior of encapsulated thermoacoustic projectors. Applications of thermoacoustic projectors for high power SONAR arrays, sound cancellation, and optimal thermal design, regarding enhanced energy conversion efficiency, are discussed.

  8. Crystalline nanostructures on Ge surfaces induced by ion irradiation

    NASA Astrophysics Data System (ADS)

    Ou, Xin; Facsko, Stefan

    2014-12-01

    Besides conventional low efficiency lithographic techniques broad ion beam irradiation is a simple and potentially mass productive technique to fabricate nanoscale patterns on various semiconductor surfaces. The main drawback of this method is that the irradiated semiconductor surfaces are amorphized, which strongly limits the potential application of these nanostructures in electronic and optoelectronic devices. In this work we report that high-quality crystalline nanostructure patterns are formed on Ge surfaces via Ar+ irradiation at elevated temperatures. This pattern formation process resembles the pattern formation in homoepitaxy. Therefore, the process is discussed based on a 'reverse epitaxy' mechanism.

  9. Novel silicon phases and nanostructures for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Wippermann, Stefan; He, Yuping; Vörös, Márton; Galli, Giulia

    2016-12-01

    Silicon exhibits a large variety of different bulk phases, allotropes, and composite structures, such as, e.g., clathrates or nanostructures, at both higher and lower densities compared with diamond-like Si-I. New Si structures continue to be discovered. These novel forms of Si offer exciting prospects to create Si based materials, which are non-toxic and earth-abundant, with properties tailored precisely towards specific applications. We illustrate how such novel Si based materials either in the bulk or as nanostructures may be used to significantly improve the efficiency of solar energy conversion devices.

  10. Novel silicon phases and nanostructures for solar energy conversion

    SciTech Connect

    Wippermann, Stefan; He, Yuping; Vörös, Márton; Galli, Giulia

    2016-12-01

    Silicon exhibits a large variety of different bulk phases, allotropes, and composite structures, such as, e.g., clathrates or nanostructures, at both higher and lower densities compared with diamond-like Si-I. New Si structures continue to be discovered. These novel forms of Si offer exciting prospects to create Si based materials, which are non-toxic and earth-abundant, with properties tailored precisely towards specific applications. We illustrate how such novel Si based materials either in the bulk or as nanostructures may be used to significantly improve the efficiency of solar energy conversion devices.

  11. Concept of quantum topology of nanostructures in the condensed state

    NASA Astrophysics Data System (ADS)

    Beznosyuk, S. A.

    1996-05-01

    The basic components of one of the central ideas forming the basis of the theory of nanostructure physics of materials are treated here. A systematic development of the quantum topology of atoms embedded in an electronic medium is given, along with the quantum-field topology of the electron loges. Their representation by kinematic electron density waves is discussed. An analysis is given of the model of nanometer-scale “corpuscles” as a certain type of compact electronic loges, including the atoms and the boundary layers of the electronic medium enclosing them. In conclusion, corpuscular mechanisms for familiar fundamental phenomena in nanostructure physics of materials are analyzed.

  12. [Specific features of rare forms of paratonsillitis].

    PubMed

    Bobrov, V M

    1997-01-01

    With decreasing number of patients subjected to tonsilectomy, the number of paratonsillitis patients, on the contrary, is on the increase. Among 1718 patients with paratonsillitis observed and treated by the author in 1985-1996, 313 had infiltration and 1405 patients--abscess stage of paratonsillitis. 284 (20.2%) of the latter underwent abscesstonsilectomy. 32, 96 and 4 patients had bilateral, recurrent and extensive paratonsillitis, respectively. Complicating parapharyngitis occurred in 55 (3.2%) patients. Opening of the abscess led to massive bleeding from incisio demanding abscesstonsilectomy. Despite previous tonsilectomy, 17 (0.99%) patients developed paratonsillitis which originated from the residual lymphoid tissue in the upper pole of the tonsil hidden in the scars. 1672 patients had tonsillogenic paratonsillitis, 46 patients exhibited odontogenic paratonsillitis.

  13. NANOSTRUCTURE PATTERNING UNDER ENERGETIC PARTICLE BEAM IRRADIATION

    SciTech Connect

    Wang, Lumin; Lu, Wei

    2013-01-31

    Energetic ion bombardment can lead to the development of complex and diverse nanostructures on or beneath the material surface through induced self-organization processes. These self-organized structures have received particular interest recently as promising candidates as simple, inexpensive, and large area patterns, whose optical, electronic and magnetic properties are different from those in the bulk materials [1-5]. Compared to the low mass efficiency production rate of lithographic methods, these self-organized approaches display new routes for the fabrication of nanostructures over large areas in a short processing time at the nanoscale, beyond the limits of lithography [1,4]. Although it is believed that surface nanostructure formation is based on the morphological instability of the sputtered surface, driven by a kinetic balance between roughening and smoothing actions [6,7], the fundamental mechanisms and experimental conditions for the formation of these nanostructures has still not been well established, the formation of the 3-D naopatterns beneath the irradiated surface especially needs more exploration. During the last funding period, we have focused our efforts on irradiation-induced nanostructures in a broad range of materials. These structures have been studied primarily through in situ electron microscopy during electron or ion irradiation. In particular, we have performed studies on 3-D void/bubble lattices (in metals and CaF2), embedded sponge-like porous structure with uniform nanofibers in irradiated semiconductors (Ge, GaSb, and InSb), 2-D highly ordered pattern of nanodroplets (on the surface of GaAs), hexagonally ordered nanoholes (on the surface of Ge), and 1-D highly ordered ripple and periodic arrays (of Cu nanoparticles) [3,8-11]. The amazing common feature in those nanopatterns is the uniformity of the size of nanoelements (nanoripples, nanodots, nanovoids or nanofibers) and the distance separating them. Our research focuses on the

  14. Process flow to integrate nanostructures on silicon grass in surface micromachined systems

    NASA Astrophysics Data System (ADS)

    Mehner, H.; Müller, L.; Biermann, S.; Hänschke, F.; Hoffmann, M.

    2016-10-01

    The process flow to integrate metallic nanostructures in surface micromachining processes is presented. The nanostructures are generated by evaporation of microstructured silicon grass with metal. The process flow is based on the lift-off of a thin amorphous silicon layer deposited using a CVD process. All steps feature a low temperature load beneath 120 °C and high compatibility with many materials as only well-established chemicals are used. As a result metallic nanostructures usable for optical applications can be generated as part of multilayered microsystems fabricated in surface micromachining.

  15. Triphenylalanine peptides self-assemble into nanospheres and nanorods that are different from the nanovesicles and nanotubes formed by diphenylalanine peptides.

    PubMed

    Guo, Cong; Luo, Yin; Zhou, Ruhong; Wei, Guanghong

    2014-03-07

    Understanding the nature of the self-assembly of peptide nanostructures at the molecular level is critical for rational design of functional bio-nanomaterials. Recent experimental studies have shown that triphenylalanine(FFF)-based peptides can self-assemble into solid plate-like nanostructures and nanospheres, which are different from the hollow nanovesicles and nanotubes formed by diphenylalanine(FF)-based peptides. In spite of extensive studies, the assembly mechanism and the molecular basis for the structural differences between FFF and FF nanostructures remain poorly understood. In this work, we first investigate the assembly process and the structural features of FFF nanostructures using coarse-grained molecular dynamics simulations, and then compare them with FF nanostructures. We find that FFF peptides spontaneously assemble into solid nanometer-sized nanospheres and nanorods with substantial β-sheet contents, consistent with the structural properties of hundred-nanometer-sized FFF nano-plates characterized by FT-IR spectroscopy. Distinct from the formation mechanism of water-filled FF nanovesicles and nanotubes reported in our previous study, intermediate bilayers are not observed during the self-assembly process of FFF nanospheres and nanorods. The peptides in FFF nanostructures are predominantly anti-parallel-aligned, which can form larger sizes of β-sheet-like structures than the FF counterparts. In contrast, FF peptides exhibit lipid-like assembly behavior and assemble into bilayered nanostructures. Furthermore, although the self-assembly of FF and FFF peptides is mostly driven by side chain-side chain (SC-SC) aromatic stacking interactions, the main chain-main chain (MC-MC) interactions also play an important role in the formation of fine structures of the assemblies. The delicate interplay between MC-MC and SC-SC interactions results in the different nanostructures formed by the two peptides. These findings provide new insights into the structure

  16. TOPICAL REVIEW: Magnetic surface nanostructures

    NASA Astrophysics Data System (ADS)

    Enders, A.; Skomski, R.; Honolka, J.

    2010-11-01

    Recent trends in the emerging field of surface-supported magnetic nanostructures are reviewed. Current strategies for nanostructure synthesis are summarized, followed by a predominantly theoretical description of magnetic phenomena in surface magnetic structures and a review of experimental research in this field. Emphasis is on Fe- or Co-based nanostructures in various low-dimensional geometries, which are studied as model systems to explore the effects of dimensionality, atomic coordination, chemical bonds, alloying and, most importantly, interactions with the supporting substrate on the magnetism. This review also includes a discussion of closely related systems, such as 3d element impurities integrated into organic networks, surface-supported Fe-based molecular magnets, Kondo systems or 4d element nanostructures that exhibit emergent magnetism, thereby bridging the traditional areas of surface science, molecular physics and nanomagnetism.

  17. Nanostructured Materials for Renewable Energy

    SciTech Connect

    2009-11-01

    This factsheet describes a research project whose overall objective is to advance the fundamental understanding of novel photoelectronic organic device structures integrated with inorganic nanostructures, while also expanding the general field of nanomaterials for renewable energy devices and systems.

  18. Ion-implanted Si-nanostructures buried in a SiO{sub 2} substrate studied with soft-x-ray spectroscopy

    SciTech Connect

    Williams, R.; Rubensson, J.E.; Eisebitt, S.

    1997-04-01

    In recent years silicon nanostructures have gained great interest because of their optical luminescence, which immediately suggests several applications, e.g., in optoelectronic devices. Nanostructures are also investigated because of the fundamental physics involved in the underlying luminescence mechanism, especially attention has been drawn to the influence of the reduced dimensions on the electronic structure. The forming of stable and well-defined nanostructured materials is one goal of cluster physics. For silicon nanostructures this goal has so far not been reached, but various indirect methods have been established, all having the problem of producing less well defined and/or unstable nanostructures. Ion implantation and subsequent annealing is a promising new technique to overcome some of these difficulties. In this experiment the authors investigate the electronic structure of ion-implanted silicon nanoparticles buried in a stabilizing SiO{sub 2} substrate. Soft X-ray emission (SXE) spectroscopy features the appropriate information depth to investigate such buried structures. SXE spectra to a good approximation map the local partial density of occupied states (LPDOS) in broad band materials like Si. The use of monochromatized synchrotron radiation (MSR) allows for selective excitation of silicon atoms in different chemical environments. Thus, the emission from Si atom sites in the buried structure can be separated from contributions from the SiO{sub 2} substrate. In this preliminary study strong size dependent effects are found, and the electronic structure of the ion-implanted nanoparticles is shown to be qualitatively different from porous silicon. The results can be interpreted in terms of quantum confinement and chemical shifts due to neighboring oxygen atoms at the interface to SiO{sub 2}.

  19. Nanostructure-induced DNA condensation

    NASA Astrophysics Data System (ADS)

    Zhou, Ting; Llizo, Axel; Wang, Chen; Xu, Guiying; Yang, Yanlian

    2013-08-01

    The control of the DNA condensation process is essential for compaction of DNA in chromatin, as well as for biological applications such as nonviral gene therapy. This review endeavours to reflect the progress of investigations on DNA condensation effects of nanostructure-based condensing agents (such as nanoparticles, nanotubes, cationic polymer and peptide agents) observed by using atomic force microscopy (AFM) and other techniques. The environmental effects on structural characteristics of nanostructure-induced DNA condensates are also discussed.

  20. Synthesis and properties of graphene oxide/graphene nanostructures

    NASA Astrophysics Data System (ADS)

    Kapitanova, O. O.; Panin, G. N.; Baranov, A. N.; Kang, T. W.

    2012-05-01

    We report preparation of graphene oxide (GO)/graphene (G) nanostructures and their structural, optical and electrical properties. GO was synthesized through oxidation of graphite by using the modified Hummer's method, in which a long oxidation time was combined with a highly effective method for purifying the reaction products. The obtained GO was partially reduced (r-GO) by adding ascorbic acid and thermal annealing. An electrical reduction/oxidation process in r-GO under an electric field was used to form and control the GO/G nanostructures and the potential barrier at the interface. After the treatment, the ratio of the intensity of peak G (1578 cm-1) to that of peak D (1357 cm-1) in Raman spectra of the samples is increased, which is attributed to an increase in the ratio between the sp2 and sp3 regions. The electrical and the luminescence characteristics of the GO/G nanostructures were investigated.

  1. Tunable morphologies of indium tin oxide nanostructures using nanocellulose templates

    DOE PAGES

    Aytug, Tolga; Meyer, III, Harry M.; Ozcan, Soydan; ...

    2015-01-01

    Metal oxide nanostructures have emerged as an important family of materials for various device applications. The performance is highly dependent on the morphology of the metal oxide nanostructures. Here we report a completely green approach to prepare indium tin oxide (ITO) nanoparticles using only water and cellulose nanofibril (CNF) in addition to the ITO precursor. Surface hydroxyl groups of the CNFs allow for efficient conjugation of ITO precursors (e.g., metal ions) in aqueous solution. The resulting CNF film allows for controllable spatial arrangement of metal oxide precursors, which results in tunable particle morphology (e.g., nanowires, nanospheres, and octahedral nanoparticles). Thesemore » ITO nanoparticles can also form conductive and transparent ITO films. This study opens a new perspective on developing metal oxide nanostructures.« less

  2. Tunable morphologies of indium tin oxide nanostructures using nanocellulose templates

    SciTech Connect

    Aytug, Tolga; Meyer, III, Harry M.; Ozcan, Soydan; Lu, Yuan; Poole, II, Joseph E.

    2015-01-01

    Metal oxide nanostructures have emerged as an important family of materials for various device applications. The performance is highly dependent on the morphology of the metal oxide nanostructures. Here we report a completely green approach to prepare indium tin oxide (ITO) nanoparticles using only water and cellulose nanofibril (CNF) in addition to the ITO precursor. Surface hydroxyl groups of the CNFs allow for efficient conjugation of ITO precursors (e.g., metal ions) in aqueous solution. The resulting CNF film allows for controllable spatial arrangement of metal oxide precursors, which results in tunable particle morphology (e.g., nanowires, nanospheres, and octahedral nanoparticles). These ITO nanoparticles can also form conductive and transparent ITO films. This study opens a new perspective on developing metal oxide nanostructures.

  3. Wear Behavior of Nanostructured Hypoeutectic Fe-B Alloy

    NASA Astrophysics Data System (ADS)

    Fu, Licai; Yang, Jun; Zhou, Lingping; Liu, Weimin

    The wear behavior of nanostructured hypoeutectic Fe94.3B5.7 alloy was investigated in comparison with coarse grained counterpart. The friction coefficient of the Fe94.3B5.7 alloy changed slightly with grain size. While the wear rate decreased as the grain size decreased to nano scale. Both Fe2O3 and Fe2SiO4 oxides were found on the worn surfaces in the nanostructured Fe94.3B5.7 alloy, but only a few oxide films were observed for the coarse grained counterpart. These results suggested that the nanostructured eutectic was conducive to forming oxide films on the worn surface of the Fe94.3B5.7 alloy, and improved the wear resistance.

  4. Metallic glass nanostructures of tunable shape and composition

    PubMed Central

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J.; Schroers, Jan

    2015-01-01

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top–down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties. PMID:25901951

  5. Zinc oxide's hierarchical nanostructure and its photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Kanjwal, Muzafar A.; Sheikh, Faheem A.; Barakat, Nasser A. M.; Li, Xiaoqiang; Kim, Hak Yong; Chronakis, Ioannis S.

    2012-02-01

    In this study, a new hierarchical nanostructure that consists of zinc oxide (ZnO) was produced by the electrospinning process followed by a hydrothermal technique. First, electrospinning of a colloidal solution that consisted of zinc nanoparticles, zinc acetate dihydrate and poly(vinyl alcohol) was performed to produce polymeric nanofibers embedding solid nanoparticles. Calcination of the obtained electrospun nanofiber mats in air at 500 °C for 90 min produced pure ZnO nanofibers with rough surfaces. The rough surface strongly enhanced outgrowing of ZnO nanobranches when a specific hydrothermal technique was used. Methylene blue dihydrate was used to check the photocatalytic ability of the produced nanostructures. The results indicated that the hierarchical nanostructure had a better performance than the other form.

  6. Noble-metal nanostructures on carburized W(110)

    NASA Astrophysics Data System (ADS)

    Bachmann, Magdalena; Memmel, Norbert; Bertel, Erminald

    2011-07-01

    Noble metal nanostructures of Au, Ag and Cu were prepared on two types of carbon-modified W(110) surfaces-R(15 × 12) and R(15 × 3)-and investigated by means of scanning tunneling microscopy. For all deposited metals qualitatively the same behaviour is observed: On the R(15 × 12)-template always isotropic clusters are formed. In contrast, on the R(15 × 3)-substrate the anisotropy of the nanostructures can be tuned from clusters at low temperatures via thin nanowires to thicker nanobars at high deposition temperatures. At intermediate temperatures on the R(15 × 3) the anisotropic Au nanowires arrange themselves into straight lines along domain boundaries induced by deposition of the Au metal. Similarities and differences to Au nanostructures as recently reported by Varykhalov et al. [A. Varykhalov, O. Rader, W. Gudat. Physical Review B 77, 035412 (2008).] are discussed.

  7. Metallic glass nanostructures of tunable shape and composition.

    PubMed

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J; Schroers, Jan

    2015-04-22

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top-down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties.

  8. Stabilizing nanostructures in metals using grain and twin boundary architectures

    NASA Astrophysics Data System (ADS)

    Lu, K.

    2016-05-01

    Forming alloys with impurity elements is a routine method for modifying the properties of metals. An alternative approach involves the incorporation of interfaces into the crystalline lattice to enhance the metal's properties without changing its chemical composition. The introduction of high-density interfaces in nanostructured materials results in greatly improved strength and hardness; however, interfaces at the nanoscale show low stability. In this Review, I discuss recent developments in the stabilization of nanostructured metals by modifying the architectures of their interfaces. The amount, structure and distribution of several types of interfaces, such as high- and low-angle grain boundaries and twin boundaries, are discussed. I survey several examples of materials with nanotwinned and nanolaminated structures, as well as with gradient nanostructures, describing the techniques used to produce such samples and tracing their exceptional performances back to the nanoscale architectures of their interfaces.

  9. Nanostructure formation in the lecithin/isooctane/water system.

    PubMed

    Koifman, Naama; Schnabel-Lubovsky, Maya; Talmon, Yeshayahu

    2013-08-15

    We present here for the first time a study of the self-assembled nanostructures in the lecithin/isooctane/water system by direct-imaging techniques, namely, cryogenic transmission electron microscopy (cryo-TEM) and cryogenic scanning electron microscopy (cryo-SEM). Along the dilution line [water]/[lecithin] = 5, we identified a nanostructural development with the increase of lecithin concentration. The system changes from a single reverse micellar phase, through a reverse micellar phase coexisting with a lamellar phase, and finally to a reverse liquid crystalline cubic phase and a lamellar phase. We compared the nanostructures formed when phosphatidylcholine rather than naturally occurring lecithin is used and found that both phase behavior and nanostructure are significantly different. The use of the two complementary cryo-EM techniques proved very efficient in the nanostructural characterization of the system. We also performed small-angle X-ray scattering to confirm our findings. Since the system is very sensitive to changes in composition, the cryo-EM specimens were prepared in a Controlled Environment Vitrification System (CEVS) that has been modified for our specimen preparation needs. We were able to overcome the challenges involved in directly imaging this nonaqueous (oil-rich), concentrated complex liquid systems, thus extending the usefulness of those characterization techniques.

  10. Intrinsic instability of thin liquid films on nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Sun, L.; Hu, H.; Rokoni, A. A.; Sun, Y.

    2016-09-01

    The instability of a thin liquid film on nanostructures is not well understood but is important in liquid-vapor two-phase heat transfer (e.g., thin film evaporation and boiling), lubrication, and nanomanufacturing. In thin film evaporation, the comparison between the non-evaporating film thickness and the critical film breakup thickness determines the stability of the film: the film becomes unstable when the critical film breakup thickness is larger than the non-evaporating film thickness. In this study, a closed-form model is developed to predict the critical breakup thickness of a thin liquid film on 2D periodic nanostructures based on the minimization of system free energy in the limit of a liquid monolayer. Molecular dynamics simulations are performed for water thin films on square nanostructures of varying depth and wettability, and the simulations agree with the model predictions. The results show that the critical film breakup thickness increases with the nanostructure depth and the surface wettability. The model developed here enables the prediction of the minimum film thickness for a stable thin film evaporation on a given nanostructure.

  11. Intrinsic instability of thin liquid films on nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Rokoni, Arif; Hu, Han; Sun, Liyong; Sun, Ying

    2016-11-01

    The instability of a thin liquid film on nanostructures is not well understood but is important in liquid-vapor two-phase heat transfer (e.g., thin film evaporation and boiling), lubrication, and nanomanufacturing. In thin film evaporation, the comparison between the non-evaporating film thickness and the critical film breakup thickness determines the stability of the film: the film becomes unstable when the critical film breakup thickness is larger than the non-evaporating film thickness. In this study, a closed-form model is developed to predict the critical breakup thickness of a thin liquid film on 2D periodic nanostructures based on minimization of system free energy in the limit of a liquid monolayer. Molecular dynamics simulations are performed for water thin films on square nanostructures of varying depth and wettability and the simulations agree with the model predictions. The results show that the critical film breakup thickness increases with the nanostructure depth and the surface wettability. The model developed here enables the prediction of the minimum film thickness for stable thin film evaporation on a given nanostructure.

  12. Reactive nanostructured membranes for water purification.

    PubMed

    Lewis, Scott R; Datta, Saurav; Gui, Minghui; Coker, Eric L; Huggins, Frank E; Daunert, Sylvia; Bachas, Leonidas; Bhattacharyya, Dibakar

    2011-05-24

    Many current treatments for the reclamation of contaminated water sources are chemical-intensive, energy-intensive, and/or require posttreatment due to unwanted by-product formation. We demonstrate that through the integration of nanostructured materials, enzymatic catalysis, and iron-catalyzed free radical reactions within pore-functionalized synthetic membrane platforms, we are able to conduct environmentally important oxidative reactions for toxic organic degradation and detoxification from water without the addition of expensive or harmful chemicals. In contrast to conventional, passive membrane technologies, our approach utilizes two independently controlled, nanostructured membranes in a stacked configuration for the generation of the necessary oxidants. These include biocatalytic and organic/inorganic (polymer/iron) nanocomposite membranes. The bioactive (top) membrane contains an electrostatically immobilized enzyme for the catalytic production of one of the main reactants, hydrogen peroxide (H(2)O(2)), from glucose. The bottom membrane contains either immobilized iron ions or ferrihydrite/iron oxide nanoparticles for the decomposition of hydrogen peroxide to form powerful free radical oxidants. By permeating (at low pressure) a solution containing a model organic contaminant, such as trichlorophenol, with glucose in oxygen-saturated water through the membrane stack, significant contaminant degradation was realized. To illustrate the effectiveness of this membrane platform in real-world applications, membrane-immobilized ferrihydrite/iron oxide nanoparticles were reacted with hydrogen peroxide to form free radicals for the degradation of a chlorinated organic contaminant in actual groundwater. Although we establish the development of these nanostructured materials for environmental applications, the practical and methodological advances demonstrated here permit the extension of their use to applications including disinfection and/or virus inactivation.

  13. Reactive nanostructured membranes for water purification

    PubMed Central

    Lewis, Scott R.; Datta, Saurav; Gui, Minghui; Coker, Eric L.; Huggins, Frank E.; Daunert, Sylvia; Bachas, Leonidas; Bhattacharyya, Dibakar

    2011-01-01

    Many current treatments for the reclamation of contaminated water sources are chemical-intensive, energy-intensive, and/or require posttreatment due to unwanted by-product formation. We demonstrate that through the integration of nanostructured materials, enzymatic catalysis, and iron-catalyzed free radical reactions within pore-functionalized synthetic membrane platforms, we are able to conduct environmentally important oxidative reactions for toxic organic degradation and detoxification from water without the addition of expensive or harmful chemicals. In contrast to conventional, passive membrane technologies, our approach utilizes two independently controlled, nanostructured membranes in a stacked configuration for the generation of the necessary oxidants. These include biocatalytic and organic/inorganic (polymer/iron) nanocomposite membranes. The bioactive (top) membrane contains an electrostatically immobilized enzyme for the catalytic production of one of the main reactants, hydrogen peroxide (H2O2), from glucose. The bottom membrane contains either immobilized iron ions or ferrihydrite/iron oxide nanoparticles for the decomposition of hydrogen peroxide to form powerful free radical oxidants. By permeating (at low pressure) a solution containing a model organic contaminant, such as trichlorophenol, with glucose in oxygen-saturated water through the membrane stack, significant contaminant degradation was realized. To illustrate the effectiveness of this membrane platform in real-world applications, membrane-immobilized ferrihydrite/iron oxide nanoparticles were reacted with hydrogen peroxide to form free radicals for the degradation of a chlorinated organic contaminant in actual groundwater. Although we establish the development of these nanostructured materials for environmental applications, the practical and methodological advances demonstrated here permit the extension of their use to applications including disinfection and/or virus inactivation. PMID

  14. Ultraflexible nanostructures and implications for future nanorobots

    NASA Astrophysics Data System (ADS)

    Cohn, Robert W.; Panchapakesan, Balaji

    2016-05-01

    Several high aspect ratio nanostructures have been made by capillary force directed self-assembly including polymeric nanofiber air-bridges, trampoline-like membranes, microsphere-beaded nanofibers, and intermetallic nanoneedles. Arrays of polymer air-bridges form in seconds by simply hand brushing a bead of polymeric liquid over an array of micropillars. The domination of capillary force that is thinning unstable capillary bridges leads to uniform arrays of nanofiber air-bridges. Similarly, arrays of vertically oriented Ag2Ga nanoneedles have been formed by dipping silvercoated arrays of pyramidal silicon into melted gallium. Force-displacement measurements of these structures are presented. These nanostructures, especially when compressively or torsionally buckled, have extremely low stiffnesses, motion due to thermal fluctuations that is relatively easily detected, and the ability to move great distances for very small changes in applied force. Nanofibers with bead-on-a-string structure, where the beads are micron diameter and loaded with magnetic iron oxide (maghemite), are shown to be simply viewable under optical microscopes, have micronewton/ m stiffness, and have ultralow torsional stiffnesses enabling the bead to be rotated numerous revolutions without breaking. Combination of these high aspect ratio structures with stretched elastomers offer interesting possibilities for robotic actuation and locomotion. Polydimethylsiloxane loaded with nanomaterials, e.g. nanotubes, graphene or MoS2, can be efficiently heated with directed light. Heating produces considerable force through the thermoelastic effect, and this force can be used for continuous translation or to trigger reversible elastic buckling of the nanostructures. The remote stimulation of motion with light provides a possible mechanism for producing cooperative behavior between swarms of semiautonomous nanorobots.

  15. Nanostructured liquid-crystalline particles for drug delivery.

    PubMed

    Lancelot, Alexandre; Sierra, Teresa; Serrano, José Luis

    2014-04-01

    Nanostructured lyotropic liquid crystal particles (LLC NPs) have proven to be extremely useful tools for applications in drug delivery. These structured nanoparticles are formed by amphiphilic molecules and contain internal water channels, which are not in contact with external water, and where polar drugs can situate; on the other hand, apolar drugs can be loaded in the lipophilic part of the structure and the amphiphilic drugs can locate at the polar/apolar interfaces. A revision of the most relevant results published in the field of LLC NPs has been made. The first section discusses the most common compounds used in these nanoparticles and their preparation and characterization. A summary of recent and relevant results including the composition and type of nanoparticles used, the illness treated, the administration via and some special features in each case have been summarized in a table. LLC NPs are highly versatile drug delivery systems, which can be applied by topical, oral and intravenous treatments. Especially relevant is their use for the release of anticancer drugs, biomolecules and vaccines. Nevertheless a number of critical points need to be solved in order to attain practical applications.

  16. Organic phase synthesis of noble metal-zinc chalcogenide core-shell nanostructures.

    PubMed

    Kumar, Prashant; Diab, Mahmud; Flomin, Kobi; Rukenstein, Pazit; Mokari, Taleb

    2016-10-15

    Multi-component nanostructures have been attracting tremendous attention due to their ability to form novel materials with unique chemical, optical and physical properties. Development of hybrid nanostructures that are composed of metal-semiconductor components using a simple approach is of interest. Herein, we report a robust and general organic phase synthesis of metal (Au or Ag)-Zinc chalcogenide (ZnS or ZnSe) core-shell nanostructures. This synthetic protocol also enabled the growth of more compositionally complex nanostructures of Au-ZnSxSe1-x alloys and Au-ZnS-ZnSe core-shell-shell. The optical and structural properties of these hybrid nanostructures are also presented.

  17. Fabrication of hierarchical ZnO nanostructures on cotton fabric for wearable device applications

    NASA Astrophysics Data System (ADS)

    Pandiyarasan, V.; Suhasini, S.; Archana, J.; Navaneethan, M.; Majumdar, Abhijit; Hayakawa, Y.; Ikeda, H.

    2017-10-01

    We have investigated ZnO nanostructures on cotton fabric (CF) s a flexible material for an application of wearable thermoelectric (TE) power generator which requires super-hydrophobicity, UV protection, and high TE efficiency. Field emission scanning electron microscopy images revealed that the formed ZnO nanostructures have a mixture of nanorods and nanosheets and are uniformly coated on the CF. XRD pattern and Raman spectra revealed that the ZnO nanostructure has a wurtzite structure. Contact angle measurements showed that the ZnO-nanostructures-coated CF possessed a high super hydrophobic nature with an angle of 132.5°. ZnO nanocomposite/CF sample exhibited an excellent UV protection factor 183.84. Seebeck coefficient, electrical resistivity and thermoelectric power factor of the ZnO nanostructures on cotton fabric were evaluated to be 28 μV/K, 0.04 Ω-cm, and 22 μW/m K2, respectively.

  18. Use of facile mechanochemical method to functionalize carbon nanofibers with nanostructured polyaniline and their electrochemical capacitance

    NASA Astrophysics Data System (ADS)

    Du, Xusheng; Liu, Hong-Yuan; Cai, Guipeng; Mai, Yiu-Wing; Baji, Avinash

    2012-02-01

    A facile approach to functionalize carbon nanofibers [CNFs] with nanostructured polyaniline was developed via in situ mechanochemical polymerization of polyaniline in the presence of chemically treated CNFs. The nanostructured polyaniline grafting on the CNF was mainly in a form of branched nanofibers as well as rough nanolayers. The good dispersibility and processability of the hybrid nanocomposite could be attributed to its overall nanostructure which enhanced its accessibility to the electrolyte. The mechanochemical oxidation polymerization was believed to be related to the strong Lewis acid characteristic of FeCl3 and the Lewis base characteristic of aniline. The growth mechanism of the hierarchical structured nanofibers was also discussed. After functionalization with the nanostructured polyaniline, the hybrid polyaniline/CNF composite showed an enhanced specific capacitance, which might be related to its hierarchical nanostructure and the interaction between the aromatic polyaniline molecules and the CNFs.

  19. Versatile Micropatterning of Plasmonic Nanostructures by Visible Light Induced Electroless Silver Plating on Gold Nanoseeds.

    PubMed

    Yoshikawa, Hiroyuki; Hironou, Asami; Shen, ZhengJun; Tamiya, Eiichi

    2016-09-14

    A versatile fabrication technique for plasmonic silver (Ag) nanostructures that uses visible light exposure for micropatterning and plasmon resonance tuning is presented. The surface of a glass substrate modified with gold (Au) nanoseeds by a thermal dewetting process was used as a Ag plating platform. When a solution containing silver nitrate and sodium citrate was dropped on the Au nanoseeds under visible light exposure, the plasmon-mediated reduction of Ag ions was induced on the Au nanoseeds to form Ag nanostructures. The plasmon resonance spectra of Ag nanostructures were examined by an absorption spectral measurement and a finite-difference time-domain (FDTD) simulation. Some examples of Ag nanostructure patterning were demonstrated by means of light exposure through a photomask, direct writing with a focused laser beam, and the interference between two laser beams. Surface enhanced Raman spectroscopy (SERS) of 4-aminothiophenol (4-ATP) was conducted with fabricated Ag nanostructures.

  20. Effect of laser parameters and assist gas on spectral response of silicon fibrous nanostructure

    SciTech Connect

    Mahmood, Abdul Salam; Venkatakrishnan, Krishnan; Alubiady, M.; Tan, Bo

    2010-11-15

    This article report, for the first time, the influence of laser parameters on the spectral response of weblike silicon fibrous nanostructures. These nanostructures are formed by femtosecond laser irradiation at megahertz pulse frequency under atmosphere and nitrogen ambient. The observed decreasing in reflectance is correlated with the density of fibrous nanostructures and the size of the agglomerated nanoparticles. Compared to bulk silicon, Raman spectra of fibrous nanostructures shows a downward shift and asymmetric broadening at the first order phonon peak. The shift and broadening are attributed to phonon confinement of fibrous nanostructure. Polarization and nitrogen gas modify the morphology of generated nanomaterials but does not have effect on light absorptance. Pulsewidth and pulse frequency do not have significant effect on light absorptance.

  1. Use of facile mechanochemical method to functionalize carbon nanofibers with nanostructured polyaniline and their electrochemical capacitance

    PubMed Central

    2012-01-01

    A facile approach to functionalize carbon nanofibers [CNFs] with nanostructured polyaniline was developed via in situ mechanochemical polymerization of polyaniline in the presence of chemically treated CNFs. The nanostructured polyaniline grafting on the CNF was mainly in a form of branched nanofibers as well as rough nanolayers. The good dispersibility and processability of the hybrid nanocomposite could be attributed to its overall nanostructure which enhanced its accessibility to the electrolyte. The mechanochemical oxidation polymerization was believed to be related to the strong Lewis acid characteristic of FeCl3 and the Lewis base characteristic of aniline. The growth mechanism of the hierarchical structured nanofibers was also discussed. After functionalization with the nanostructured polyaniline, the hybrid polyaniline/CNF composite showed an enhanced specific capacitance, which might be related to its hierarchical nanostructure and the interaction between the aromatic polyaniline molecules and the CNFs. PMID:22315992

  2. Electrochemical Synthesis of Nanostructured Noble Metal Films for Biosensing

    NASA Astrophysics Data System (ADS)

    Bhattarai, Jay K.

    Nanostructures of noble metals (gold and silver) are of interest because of their important intrinsic properties. Noble metals by themselves are physically robust, chemically inert, highly conductive, and possess the capability to form strong bonds with thiols or dithiol molecules present in organic compounds, creating self-assembled monolayers with tunable functional groups at exposed interfaces. However, when the nanostructures are formed, they in addition possess high surface area and unique optical properties which can be tuned by adjusting the shape and the size of the nanostructures. All of these properties make nanostructures of noble metals suitable candidates to be used as a transducer for optical and electrochemical biosensing. Individual nanostructures might be easier to prepare but difficult to handle to use as a transducer. Therefore, we prepared and analyzed nanostructured films/coating of noble metals and used them as a transducer for optical and electrochemical biosensing. We have electrochemically prepared nanoporous gold (NPG) on gold wire varying different dependable parameters (deposition potential, time, and compositional ratio) to obtain an optimal structure in term of stability, morphology, and better surface area. NPG prepared using a deposition potential of --1.0 V for 10 min from 30:70% 50 mM potassium dicyanoaurate(I) and 50 mM potassium dicyanoargentate(I) was used as an optimal surface for protein immobilization, and to perform square wave voltammetry (SWV) based enzyme-linked lectinsorbent assays. On flat gold surfaces, adjacent protein molecules sterically block their active sites due to high-density packing, which can be minimized using NPG as a substrate. NPG can also show significant peak current in SWV experiments, a sensitive electrochemical technique that minimizes non-Faradaic current, which is difficult to obtain using a flat gold surface. These all make NPG a suitable substrate, electrode, and transducer to be used in

  3. (Plasmonic Metal Core)/(Semiconductor Shell) Nanostructures

    NASA Astrophysics Data System (ADS)

    Fang, Caihong

    shape is maintained throughout the sulfidation process, with the edge length being increased gradually. TiO2 is one of the most important semiconductors that are employed in light-harvesting applications. It has been extensively studied for a variety of applications by virtue of its low toxicity, biological compatibility, chemical and thermal stability, resistance to photocorrosion, and relative abundance. However, the photocatalytic activity of TiO2 is limited to the UV region because of its wide band gap, which limits its applications in light harvesting. Although (Au core)/(TiO2 shell) nanostructures can improve the photocatalytic activities of TiO2 in visible light, it has only been demonstrated in a few experiments and has been limited with Au nanospheres. Compared with Au nanospheres, Au nanorods offer more attractive plasmonic features, including stronger electric field enhancements and synthetically tunable longitudinal plasmon wavelengths over the visible to near-infrared region. The coating of Au nanorod therefore can largely improve light harvesting capability of TiO2. In this thesis, I developed a facile and versatile method for the preparation of (Au nanocrystal core)/(TiO2 shell) nanostructures by using a Ti(III) compound as the titania precursor. By employing Au nanorods with different sizes and varying the shell thickness, the plasmonic bands of the core/shell nanostructures can be tailored. TiO2 can also be grown on other monometallic and bimetallic Pd, Pt, Au nanocrystals. As a proof-of-concept application, (Au nanorod core)/(TiO2 shell) nanostructures were utilized in dye-sensitized solar cells to function as a scattering layer. The resultant solar cells exhibited higher power conversion efficiencies with a thinner thickness compared to the traditional TiO 2 solar cells. In addition, I also examined the property of plasmon-enhanced reactive oxygen species generation. Moreover, the TiO2 shell with a high refractive index can efficiently couple with the

  4. The influence of aminophylline on the nanostructure and nanomechanics of T lymphocytes: an AFM study

    NASA Astrophysics Data System (ADS)

    Huang, Xun; He, Jiexiang; Liu, Mingxian; Zhou, Changren

    2014-09-01

    Although much progress has been made in the illustration of the mechanism of aminophylline (AM) treating asthma, there is no data about its effect on the nanostructure and nanomechanics of T lymphocytes. Here, we presented atomic force spectroscopy (AFM)-based investigations at the nanoscale level to address the above fundamental biophysical questions. As increasing AM treatment time, T lymphocytes' volume nearly double increased and then decreased. The changes of nanostructural features of the cell membrane, i.e., mean height of particles, root-mean-square roughness (Rq), crack and fragment appearance, increased with AM treatment time. T lymphocytes were completely destroyed with 96-h treatment, and they existed in the form of small fragments. Analysis of force-distance curves showed that the adhesion force of cell surface decreased significantly with the increase of AM treatment time, while the cell stiffness increased firstly and then decreased. These changes were closely correlated to the characteristics and process of cell oncosis. In total, these quantitative and qualitative changes of T lymphocytes' structure and nanomechanical properties suggested that AM could induce T lymphocyte oncosis to exert anti-inflammatory effects for treating asthma. These findings provide new insights into the T lymphocyte oncosis and the anti-inflammatory mechanism and immune regulation actions of AM.

  5. The influence of aminophylline on the nanostructure and nanomechanics of T lymphocytes: an AFM study.

    PubMed

    Huang, Xun; He, Jiexiang; Liu, Mingxian; Zhou, Changren

    2014-01-01

    Although much progress has been made in the illustration of the mechanism of aminophylline (AM) treating asthma, there is no data about its effect on the nanostructure and nanomechanics of T lymphocytes. Here, we presented atomic force spectroscopy (AFM)-based investigations at the nanoscale level to address the above fundamental biophysical questions. As increasing AM treatment time, T lymphocytes' volume nearly double increased and then decreased. The changes of nanostructural features of the cell membrane, i.e., mean height of particles, root-mean-square roughness (Rq), crack and fragment appearance, increased with AM treatment time. T lymphocytes were completely destroyed with 96-h treatment, and they existed in the form of small fragments. Analysis of force-distance curves showed that the adhesion force of cell surface decreased significantly with the increase of AM treatment time, while the cell stiffness increased firstly and then decreased. These changes were closely correlated to the characteristics and process of cell oncosis. In total, these quantitative and qualitative changes of T lymphocytes' structure and nanomechanical properties suggested that AM could induce T lymphocyte oncosis to exert anti-inflammatory effects for treating asthma. These findings provide new insights into the T lymphocyte oncosis and the anti-inflammatory mechanism and immune regulation actions of AM.

  6. Application of aqueous dispersions of silver nanostructures for treatment of pyoinflammatory diseases with a chronic component

    NASA Astrophysics Data System (ADS)

    Rutberg, Ph; Kolikov, V.; Snetov, V.; Stogov, A.; Moshkin, A.; Khalilov, M.

    2011-01-01

    Bactericidal properties of aqueous dispersions of oxide silver nanostructures (ADSN) produced by means of pulsed electric discharges (PED) in water can use in surgery for treatment of upper purulent wounds with a chronic component. The patients with such wounds are of large number and differ on etiology of diseases but their mutual feature is long treatment without marked positive changes. Thus long application of antibiotics leads to abnormality of immune processes and antibacterial resistance of microbial flora. Moreover, local antiseptics are frequently toxic and one can oppress processes of reparation in a wound. The investigation is addressed to finding out the opportunity of usage of an ADSN for treatment of purulent wounds with a chronic component and comparison of its efficiency with the sodium hypochlorite. At investigation, the ADSN formed at PED of 5 - 10 μs duration, with highest share of "small" (hydrodynamic diameter <= 100 nm) nanostructures and greatest surface electric charge we used. It was found that the usage of ADSN during the first 5 days characterized by high active reparative processes with their maximum at 3rd - 4th days and subsequent moderate further healing. At local use of ADSN, there were no cellular atypia and preternatural representations about inflammatory reactions. It is possible to assume that usage of ADSN will allow in prospect to correct the practice of out-patient therapy of chronic and slow pyoinflammatory diseases.

  7. Toward Nanostructured Thermoelectrics. Synthesis and Characterization of Lead Telluride Gels and Aerogels

    SciTech Connect

    Ganguly, Shreyashi; Brock, Stephanie L.

    2011-05-12

    The synthesis and characterization of lead telluride (PbTe) gels and aerogels with nanostructured features of potential benefit for enhanced thermoelectrics is reported. In this approach, discrete thiolate-capped PbTe nanoparticles were synthesized by a solution-based approach followed by oxidation-induced nanoparticle assembly with tetranitromethane or hydrogen peroxide to form wet gels. Drying of the wet gels by supercritical CO₂ extraction yielded aerogels, whereas xerogels were produced by ambient pressure bench top drying. The gels consist of an interconnected network of colloidal nanoparticles and pores with surface areas up to 74 m² g-1. The thermal stability of the nanostructures relative to nanoparticles was probed with the help of in situ transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The aerogels were observed to sublime at a higher temperature and over a larger range (425–500 °C) relative to the precursor nanoparticles. TGA-DSC suggests that organic capping groups can be removed in the region 250–450 °C, and melting of PbTe nanoparticles occurs near the temperature for bulk materials (ca. 920 °C). The good thermal stability combined with the presence of nanoscale interfaces suggests PbTe gels may show promise in thermoelectric devices.

  8. The formation of a multipeak relief on the surface on nanostructured nickel and field electron emission from it

    NASA Astrophysics Data System (ADS)

    Nazarov, K. S.; Khisamov, R. Kh.; Yumaguzin, Yu. M.; Mulyukov, R. R.

    2015-06-01

    Studies of the relief formed on the surface of nanostructured nickel with nonequilibrium grain boundaries formed upon ion-beam sputtering are presented. It has been shown that the relief on the nano-structured nickel surface differs substantially from the relief formed on the surface of the coarse-grained nickel with equilibrium grain boundaries. In particular, a multipeak relief with submicron dimensionality of the peaks forms on the surface of nanostructured nickel under certain conditions. This relief is advantageous for the field electron emission. For the sample with multipeak relief, a CVC of field electron emission is measured.

  9. Fabrication and characterization of ordered arrays of nanostructures

    NASA Astrophysics Data System (ADS)

    Larson, Preston

    2005-11-01

    Nanostructures are currently of great interest because of their unique properties and potential applications in a wide range of areas such as opto-electronic and biomedical devices. Current research in nanotechnology involves fabrication and characterization of these structures, as well as theoretical and experimental studies to explore their unique and novel properties. Not only do nanostructures have the potential to be both evolutionary (state-of-the-art ICs have more and more features on the nanoscale) but revolutionary (quantum computing) as well. In this thesis, a combination of bottom-up and top-down approaches is explored to fabricate ordered arrays of nanostrucutures. The bottom-up approach involves the growth of self-organized porous anodic aluminum oxide (AAO) films. AAO films consist of a well ordered hexagonal array of close-packed pores with diameters and spacings ranging from around 5 to 500 nm. Via a top-down approach, these AAO films are then used as masks or templates to fabricate ordered arrays of nanostructures (i.e. dots, holes, meshes, pillars, rings, etc.) of various materials using conventional deposition and/or etching techniques. Using AAO films as masks allows a simple and economical method to fabricate arrays of structures with nano-scale dimensions. Furthermore, they allow the fabrication of large areas (many millimeters on a side) of highly uniform and well-ordered arrays of nanostructures, a crucial requirement for most characterization techniques and applications. Characterization of these nanostructures using various techniques (electron microscopy, atomic force microscopy, UV-Vis absorption spectroscopy, photoluminescence, capacitance-voltage measurements, magnetization hysteresis curves, etc.) will be presented. Finally, these structures provide a unique opportunity to determine the single and collective properties of nanostructure arrays and will have various future applications including but not limited to: data storage, light

  10. Femtosecond laser induced periodic nanostructures on titanium dioxide film for improving biocompatibility

    NASA Astrophysics Data System (ADS)

    Shinonaga, T.; Horiguchi, N.; Tsukamoto, M.; Nagai, A.; Yamashita, K.; Hanawa, T.; Matsushita, N.; Guoqiang, X.; Abe, N.

    2013-03-01

    Periodic nanostructures formation on Titanium dioxide (TiO2) film by scanning of femtosecond laser beam spot at fundamental and second harmonic wave is reported. Titanium (Ti) is one of the most widely used for biomaterials, because of its excellent anti-corrosion and high mechanical properties. However, Ti implant is typically artificial materials and has no biofunction. Hence, it is necessary for improving the bioactivity of Ti. Recently, coating of TiO2 film on Ti plate surface is useful methods to improve biocompatibility of Ti plate. Then, if periodic nanostructures were formed on the film surface, cell spreading might be controlled at one direction. We propose periodic nanostructures formation on TiO2 film by femtosecond laser irradiation. Cell spread could be controlled along the grooves of periodic nanostructures. In the experiments, the film was formed on Ti plate with an aerosol beam. A commercial femtosecond Ti : sapphire laser system was employed in our experiments. Periodic nanostructures, lying perpendicular to the laser electric field polarization vector, were formed on the film at fundamental and second harmonic wave. Periodic nanostructures were also produced on Ti plate with femtosecond laser. The period of periodic nanostructures on the film was much shorter than that on Ti plate. By cell test, there was a region of cell spreading along the grooves of periodic nanostructures on the film formed with femtosecond laser at fundamental wave. On bare film surface, cell spreading was observed at all direction. These results suggest that direction of cell spread could be controlled by periodic nanostructures formation on the film.

  11. LDRD final report on adaptive-responsive nanostructures for sensing applications.

    SciTech Connect

    Shelnutt, John Allen; van Swol, Frank B.; Wang, Zhongchun; Medforth, Craig J.

    2005-11-01

    Functional organic nanostructures such as well-formed tubes or fibers that can easily be fabricated into electronic and photonic devices are needed in many applications. Especially desirable from a national security standpoint are nanostructures that have enhanced sensitivity for the detection of chemicals and biological (CB) agents and other environmental stimuli. We recently discovered the first class of highly responsive and adaptive porphyrin-based nanostructures that may satisfy these requirements. These novel porphyrin nanostructures, which are formed by ionic self-assembly of two oppositely charged porphyrins, may function as conductors, semiconductors, or photoconductors, and they have additional properties that make them suitable for device fabrication (e.g., as ultrasensitive colorimetric CB microsensors). Preliminary studies with porphyrin nanotubes have shown that these nanostructures have novel optical and electronic properties, including strong resonant light scattering, quenched fluorescence, and electrical conductivity. In addition, they are photochemically active and capable of light-harvesting and photosynthesis; they may also have nonlinear optical properties. Remarkably, the nanotubes and potentially other porphyrin nanostructure are mechanically responsive and adaptive (e.g., the rigidity of the micrometers-long nanotubes is altered by light, ultrasound, or chemicals) and they self-heal upon removal the environmental stimulus. Given the tremendous degree of structural variation possible in the porphyrin subunits, additional types of nanostructures and greater control over their morphology can be anticipated. Molecular modification also provides a means of controlling their electronic, photonic, and other functional properties. In this work, we have greatly broadened the range of ionic porphyrin nanostructures that can be made, and determined the optical and responsivity properties of the nanotubes and other porphyrin nanostructures. We have

  12. Surface nanostructuring of Ni/Cu foils by femtosecond laser pulses

    SciTech Connect

    Korol'kov, V P; Ionin, Andrei A; Kudryashov, Sergei I; Seleznev, L V; Sinitsyn, D V; Samsonov, R V; Maslii, A I; Medvedev, A Zh; Gol'denberg, B G

    2011-04-30

    This work examines the effect of high-power femtosecond laser pulses on Ni/Cu bilayer foils produced by electrodeposition. We consider nanostructures formed at different laser beam parameters and under different ambient conditions. The surface nanostructures obtained in air and water have mostly the form of quasi-periodic ripples with a characteristic period of 400 - 450 and 370 - 390 nm, respectively, at a laser wavelength of 744 nm, whereas the nanostructures produced in ethanol and benzine have the form of spikes, typically spaced 400 - 700 nm apart. Femtosecond laser nanostructuring of metals is for the first time proposed, and experimentally tested, as a viable approach to producing anti-reflective coatings on the surface of polymer replicas. (laser nanotechnologies)

  13. Supercritical carbon dioxide approach to nanostructured materials

    NASA Astrophysics Data System (ADS)

    Ye, Xiang-Rong

    Supercritical fluid technology is a novel and emerging strategy to generate nanomaterials in small areas, within high-aspect-ratio structures, on complicated surfaces and poor wettable substrates with high uniformity, high homogeneity and minimum environmental problems. In this dissertation, several strategies were developed for thin film deposition and nanocomposite fabrication. In developing supercritical fluid immersion deposition (SFID), supercritical or near supercritical CO2 was used as a new solvent for immersion deposition, a galvanic displacement process traditionally carried out in aqueous HF solutions containing metal ions, to selectively develop Pd, Cu, Ag and other metal films on featured and non-featured Si substrates. Annealing of thin palladium films deposited by SFID can lead to the formation of palladium silicide in small features on Si substrates. Deposition of metal films on germanium substrates was also achieved through SFID. Through hydrogen reduction of metal-beta-diketone complexes in supercritical CO2, a rapid, convenient and environmentally benign approach has been developed to synthesize a variety of nanostructured materials: (1) Metal (Pd, Ni and Cu) nanowires and nanorods sheathed within multi-walled carbon nanotube (MWCNT) templates; (2) nanoparticles of palladium, rhodium and ruthenium decorated onto functionalized MWCNTs. These highly dispersed nanoparticles are expected to exhibit promising catalytic properties for a variety of chemical or electrochemical reactions; (3) Cu, Pd or Cu-Pd alloy nanocrystals deposited onto SiO2 nanowires (NWs), SiO2 microfibers, or SiC NWs. Different types of nanostructures were achieved, including nanocrystal-NW, spherical aggregation-NW, shell-NW composites and "mesoporous" metals supported by the framework of NWs.

  14. Morphological characteristics of selenium-containing nanostructures based on rigid-chain molecules

    NASA Astrophysics Data System (ADS)

    Ivanov, D. A.; Valueva, S. V.; Novoselov, N. P.

    2010-06-01

    Selenium-containing nanostructures of rigid-chain polymers with close molecular masses were studied by flow birefringence (FB) and static and dynamic light scattering at a fixed selenium to polymer mass ratio ν = 0.1 in solution. The group of polymers under study included the cationic polyelectrolyte poly-N,N,N,N-trimethylmethacryloyloxyethylammonium methyl sulfate, anionic polyelectrolyte carboxymethylcellulose, and nonionogen polymer oxyethylcellulose. High-molecular selenium-containing polymer nanostructures were found in all cases. Nanostructures with a maximum molecular mass and the largest number of constituent macromolecules were obtained using oxyethylcellulose. At ν = 0.1 the mean square radii of inertia of the nanostructures were almost independent of the nature of the polymer matrix. The thermodynamic state of the solutions of nanostructures was close to the ideal one in all cases. For the region where stable dispersions formed, the Gibbs energies of macromolecule-selenium nanoparticle interactions were calculated and shown to be almost independent of the nature of the polymer matrix at ν = 0.1. The close mean square radii of inertia R {g/*} of the nanostructures, the Gibbs energies of interaction, and the equivalence of the thermodynamic state of the solutions of nanostructures obtained for all polymer matrices at ν = 0.1 suggest that ν = 0.1 corresponds to the ultimate adsorption capacity of selenium nanoparticles; the considerable differences between the molecular masses (for close R {/g *} values), mean densities, and structural conformation parameters ρ* point to different packings of macromolecules in the nanostructures under study.

  15. Guanidinium-Based Polymerizable Surfactant as a Multifunctional Molecule for Controlled Synthesis of Nanostructured Materials with Tunable Morphologies.

    PubMed

    Ji, Jingwei; Zhu, Wei; Li, Jian; Wang, Peng; Liang, Yun; Zhang, Wanlin; Yin, Xianpeng; Wu, Baozhen; Li, Guangtao

    2017-06-07

    Rationally and efficiently controlling the morphology of nanomaterials plays a crucial role in significantly enhancing their functional properties and expending their applications. In this work, a strategy for controlled synthesis of diverse nanostructured materials with tunable morphologies was developed using a guanidinium-based surfactant with a polymerizable pyrrole unit as a multifunctional molecule that can serve not only as a structure-directing agent for mesostucture formation but also as a monomer and carbon source. The unique self-assembly behavior of the guanidinium head group under different conditions allows the synthesized surfactants to form different aggregates and thus to produce silica nanomaterials with multiple morphologies (such as sphere, disk, fiber, and cocoon) in conjunction with sol-gel chemistry. Besides the mesostructured silicates, by further exploring the polymerization and carbonization features of pyrrole units that were densely packed in the formed silica nanochannels, diverse nanostructured materials such as mesostructured conducting polymers, carbon materials, and metal-nanoparticle (NP)-decorated forms could also be easily obtained in one-pot fashion for various applications, such as energy storage and catalysis. As a demonstration, carbon nanotubes and Pd-NP-doped hollow carbon spheres were fabricated, which exhibited good specific capacitance (101.7 F g(-1)) at the scan rates of 5 mV s(-1) and excellent catalytic performance (100% conversion for three cycles) in the Suzuki C-C coupling reaction, respectively. All of the results indicate that our strategy may open a new avenue for efficiently accessing diverse nanostructured materials with tunable morphologies for wide applications.

  16. Engineering DNA self-assemblies as templates for functional nanostructures.

    PubMed

    Wang, Zhen-Gang; Ding, Baoquan

    2014-06-17

    CONSPECTUS: DNA is a well-known natural molecule that carries genetic information. In recent decades, DNA has been used beyond its genetic role as a building block for the construction of engineering materials. Many strategies, such as tile assembly, scaffolded origami and DNA bricks, have been developed to design and produce 1D, 2D, and 3D architectures with sophisticated morphologies. Moreover, the spatial addressability of DNA nanostructures and sequence-dependent recognition enable functional elements to be precisely positioned and allow for the control of chemical and biochemical processes. The spatial arrangement of heterogeneous components using DNA nanostructures as the templates will aid in the fabrication of functional materials that are difficult to produce using other methods and can address scientific and technical challenges in interdisciplinary research. For example, plasmonic nanoparticles can be assembled into well-defined configurations with high resolution limit while exhibiting desirable collective behaviors, such as near-field enhancement. Conducting metallic or polymer patterns can be synthesized site-specifically on DNA nanostructures to form various controllable geometries, which could be used for electronic nanodevices. Biomolecules can be arranged into organized networks to perform programmable biological functionalities, such as distance-dependent enzyme-cascade activities. DNA nanostructures can carry multiple cytoactive molecules and cell-targeting groups simultaneously to address medical issues such as targeted therapy and combined administration. In this Account, we describe recent advances in the functionalization of DNA nanostructures in different fashions based on our research efforts in nanophotonics, nanoelectronics, and nanomedicine. We show that DNA origami nanostructures can guide the assembly of achiral, spherical, metallic nanoparticles into nature-mimicking chiral geometries through hybridization between complementary DNA

  17. DNA-nanostructure-assembly by sequential spotting.

    PubMed

    Breitenstein, Michael; Nielsen, Peter E; Hölzel, Ralph; Bier, Frank F

    2011-11-18

    The ability to create nanostructures with biomolecules is one of the key elements in nanobiotechnology. One of the problems is the expensive and mostly custom made equipment which is needed for their development. We intended to reduce material costs and aimed at miniaturization of the necessary tools that are essential for nanofabrication. Thus we combined the capabilities of molecular ink lithography with DNA-self-assembling capabilities to arrange DNA in an independent array which allows addressing molecules in nanoscale dimensions. For the construction of DNA based nanostructures a method is presented that allows an arrangement of DNA strands in such a way that they can form a grid that only depends on the spotted pattern of the anchor molecules. An atomic force microscope (AFM) has been used for molecular ink lithography to generate small spots. The sequential spotting process allows the immobilization of several different functional biomolecules with a single AFM-tip. This grid which delivers specific addresses for the prepared DNA-strand serves as a two-dimensional anchor to arrange the sequence according to the pattern. Once the DNA-nanoarray has been formed, it can be functionalized by PNA (peptide nucleic acid) to incorporate advanced structures. The production of DNA-nanoarrays is a promising task for nanobiotechnology. The described method allows convenient and low cost preparation of nanoarrays. PNA can be used for complex functionalization purposes as well as a structural element.

  18. Nano-sized double helices and braids: interesting carbon nanostructures

    SciTech Connect

    Liu Jun; Zhang, X.; Zhang Yingjiu; Chen Xihua; Zhu Jing

    2003-01-25

    Two interesting carbon nanostructures, the double helices and the nanobraids, have been synthesized by pyrolysis of acetone at 715 deg. C, using iron nanoparticles as catalysts. The double helix was formed by two nanofibers, strictly coiled together with a strikingly constant pitch. Such a rope-like structure usually extended hundreds of microns in length, and provided excellent strength, stability and flexibility. The nanobraids appeared to be partially rolled up from carbon layers. Electron microscopy was applied to characterize these carbon forms.

  19. On the character of nanoscale features in reactor pressure vessel steels under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Wirth, Brian David

    Nanostructural features that form in reactor pressure vessel steels under neutron irradiation at around 290°C are responsible for significant hardening and embrittlement. It is well established that the nanostructural features can be separated into well formed precipitates and matrix features comprised of point defect clusters complexed with solutes, which may also include regions of solute enrichment that are not well formed precipitates. However, a more detailed atomicscale understanding of these features is needed to better interpret experimental measurements and provide a physical basis for predictive embrittlement models. The overall objective of this work is to provide atomic-level insight into the character of the nanostructural features and the physical processes involved in their formation. One focus of this work has been on modeling cascade aging; defined as the evolution of self-interstitial and vacancy defects spanning from their spatially correlated birth in displacement cascades over picoseconds to times on the order of >10 5 seconds, when defect populations have built up to steady-state values and no longer have a geometric correlation. During cascade aging, the self-interstitial and vacancy fluxes are responsible for radiation enhanced diffusion, resulting in wellformed precipitates, and are a direct source of matrix defect features. Many-bodied molecular-statics energy relaxation methods have been used to investigate the structure and energetics of self-interstitial and vacancy clusters. The characterization reveals that self-interstitial clusters form as highly kinked, prismatic, perfect proto dislocation loops and vacancy clusters form as faceted three-dimensional clusters. Molecular dynamics simulations of self-interstitial cluster migration reveal that they undergo easy one-dimensional glide, probably due to the presence and easy motion of intrinsic kinks. Our study of the structural characteristics and mobility of the self

  20. Clay nanotube composites for antibacterial nanostructured coatings

    NASA Astrophysics Data System (ADS)

    Boyer, Christen J.

    A surging demand for the development of new antimicrobial nanomaterials exists due to the frequency of medical device-associated infections and the transfer of pathogens from highly touched objects. Naturally occurring halloysite clay nanotubes (HNTs) have shown to be ideal particles for polymer reinforcement, time-release drug delivery, nano-reactor synthesis, and as substrate material for nanostructured coatings. This research demonstrates the feasibility of a novel method for coating HNTs with metals for antibacterial applications. The first ever ability to coat HNTs through electrolysis was developed for customizable and multi-functional antibacterial nanoparticle platforms. HNTs were investigated as substrate for the deposition of copper (Cu) and silver (Ag) metal nanoparticles through electrochemical syntheses, and as a platform for nano-structured antibacterial polymer composites. Characterization of interfacial and material properties demonstrated the feasibility of electrolysis as a new efficient and replicable nano-scale surface modification route. Methods of encapsulating HNTs in nanofibers, three-dimensional printer filaments, and multifunctional polymer rubbers were also realized. The nanofabrication methods, nanoparticles, and polymer composites created in this work were novel, scalable, easy-to-replicate, and displayed antibacterial features with tunable properties.

  1. Boron Nitride Nanostructures: Fabrication, Functionalization and Applications.

    PubMed

    Yin, Jun; Li, Jidong; Hang, Yang; Yu, Jin; Tai, Guoan; Li, Xuemei; Zhang, Zhuhua; Guo, Wanlin

    2016-06-01

    Boron nitride (BN) structures are featured by their excellent thermal and chemical stability and unique electronic and optical properties. However, the lack of controlled synthesis of quality samples and the electrically insulating property largely prevent realizing the full potential of BN nanostructures. A comprehensive overview of the current status of the synthesis of two-dimensional hexagonal BN sheets, three dimensional porous hexagonal BN materials and BN-involved heterostructures is provided, highlighting the advantages of different synthetic methods. In addition, structural characterization, functionalizations and prospective applications of hexagonal BN sheets are intensively discussed. One-dimensional BN nanoribbons and nanotubes are then discussed in terms of structure, fabrication and functionality. In particular, the existing routes in pursuit of tunable electronic and magnetic properties in various BN structures are surveyed, calling upon synergetic experimental and theoretical efforts to address the challenges for pioneering the applications of BN into functional devices. Finally, the progress in BN superstructures and novel B/N nanostructures is also briefly introduced.

  2. Plasmonic hybrid nanostructure with controlled interaction strength

    NASA Astrophysics Data System (ADS)

    Grzelak, Justyna K.; Krajnik, Bartosz; Thoreson, Mark D.; Nyga, Piotr; Shalaev, Vladimir M.; Mackowski, Sebastian

    2014-03-01

    In this report we discuss the influence of plasmon excitations in a silver island film on the fluorescence of photosynthetic complex, peridinin-chlorophyll-protein (PCP). Control of the separation between these two components is obtained by fabricating a wedge layer of silica across the substrate, with a thickness from 0 to 46 nm. Continuous variation of the silica thickness allows for gradual change of interaction strength between plasmon excitations in the metallic film and the excited states of pigments comprising photosynthetic complexes. While the largest separation between the silver film and photosynthetic complexes results in fluorescence featuring a mono-exponential decay and relatively narrow distribution of intensities, the PCP complexes placed on thinner silica spacers show biexponential fluorescence decay and significantly broader distribution of total fluorescence intensities. This broad distribution is a signature of stronger sensitivity of fluorescence enhancement upon actual parameters of a hybrid nanostructure. By gradual change of the silica spacer thickness we are able to reproduce classical distance dependence of fluorescence intensity in plasmonic hybrid nanostructures on ensemble level. Experiments carried out for different excitation wavelengths indicate that the interaction is stronger for excitations resonant with plasmon absorption in the metallic layer.

  3. Towards new functional nanostructures for medical imaging

    SciTech Connect

    Matsuura, Naomi; Rowlands, J. A.

    2008-10-15

    Nanostructures represent a promising new type of contrast agent for clinical medical imaging modalities, including magnetic resonance imaging, x-ray computed tomography, ultrasound, and nuclear imaging. Currently, most nanostructures are simple, single-purpose imaging agents based on spherical constructs (e.g., liposomes, micelles, nanoemulsions, macromolecules, dendrimers, and solid nanoparticle structures). In the next decade, new clinical imaging nanostructures will be designed as multi-functional constructs, to both amplify imaging signals at disease sites and deliver localized therapy. Proposals for nanostructures to fulfill these new functions will be outlined. New functional nanostructures are expected to develop in five main directions: Modular nanostructures with additive functionality; cooperative nanostructures with synergistic functionality; nanostructures activated by their in vivo environment; nanostructures activated by sources outside the patient; and novel, nonspherical nanostructures and components. The development and clinical translation of next-generation nanostructures will be facilitated by a combination of improved clarity of the in vivo imaging and biological challenges and the requirements to successfully overcome them; development of standardized characterization and validation systems tailored for the preclinical assessment of nanostructure agents; and development of streamlined commercialization strategies and pipelines tailored for nanostructure-based agents for their efficient translation to the clinic.

  4. Nanostructure-initiator mass spectrometry metabolite analysis and imaging.

    PubMed

    Greving, Matthew P; Patti, Gary J; Siuzdak, Gary

    2011-01-01

    Nanostructure-Initiator Mass Spectrometry (NIMS) is a matrix-free desorption/ionization approach that is particularly well-suited for unbiased (untargeted) metabolomics. An overview of the NIMS technology and its application in the detection of biofluid and tissue metabolites are presented. (To listen to a podcast about this feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html .).

  5. Nanostructures in photovoltaics.

    PubMed

    Catchpole, Kylie R

    2006-12-15

    The world has recently been waking up to the urgent need to move away from fossil fuels and towards a low-carbon economy. To achieve this, we need a way of producing electricity that is efficient, widely applicable and cheap. At the same time, there has recently been an appreciation of the tremendous scope for making entirely new types of devices, and even seeing new physics, by structuring matter at the nanoscale. Furthermore, the occurrence of self-assembly in nature suggests that a range of types of nanoscale structures could be made simply and cheaply. The application of nanostructures to photovoltaics combines a field of almost limitless possibilities with a problem of vital urgency. In this paper, some of the newer ideas emerging from this trend are described, along with how they challenge our ideas on what a solar cell looks like. We are at the beginning of a time of radically rethinking the design of the solar cell, which may lead to the exploitation of completely new physical ideas in achieving a sustainable energy future.

  6. Phonon engineering for nanostructures.

    SciTech Connect

    Aubry, Sylvie; Friedmann, Thomas Aquinas; Sullivan, John Patrick; Peebles, Diane Elaine; Hurley, David H.; Shinde, Subhash L.; Piekos, Edward Stanley; Emerson, John Allen

    2010-01-01

    Understanding the physics of phonon transport at small length scales is increasingly important for basic research in nanoelectronics, optoelectronics, nanomechanics, and thermoelectrics. We conducted several studies to develop an understanding of phonon behavior in very small structures. This report describes the modeling, experimental, and fabrication activities used to explore phonon transport across and along material interfaces and through nanopatterned structures. Toward the understanding of phonon transport across interfaces, we computed the Kapitza conductance for {Sigma}29(001) and {Sigma}3(111) interfaces in silicon, fabricated the interfaces in single-crystal silicon substrates, and used picosecond laser pulses to image the thermal waves crossing the interfaces. Toward the understanding of phonon transport along interfaces, we designed and fabricated a unique differential test structure that can measure the proportion of specular to diffuse thermal phonon scattering from silicon surfaces. Phonon-scale simulation of the test ligaments, as well as continuum scale modeling of the complete experiment, confirmed its sensitivity to surface scattering. To further our understanding of phonon transport through nanostructures, we fabricated microscale-patterned structures in diamond thin films.

  7. Topological crystalline insulator nanostructures.

    PubMed

    Shen, Jie; Cha, Judy J

    2014-11-06

    Topological crystalline insulators are topological insulators whose surface states are protected by the crystalline symmetry, instead of the time reversal symmetry. Similar to the first generation of three-dimensional topological insulators such as Bi₂Se₃ and Bi₂Te₃, topological crystalline insulators also possess surface states with exotic electronic properties such as spin-momentum locking and Dirac dispersion. Experimentally verified topological crystalline insulators to date are SnTe, Pb₁-xSnxSe, and Pb₁-xSnxTe. Because topological protection comes from the crystal symmetry, magnetic impurities or in-plane magnetic fields are not expected to open a gap in the surface states in topological crystalline insulators. Additionally, because they have a cubic structure instead of a layered structure, branched structures or strong coupling with other materials for large proximity effects are possible, which are difficult with layered Bi₂Se₃ and Bi₂Te₃. Thus, additional fundamental phenomena inaccessible in three-dimensional topological insulators can be pursued. In this review, topological crystalline insulator SnTe nanostructures will be discussed. For comparison, experimental results based on SnTe thin films will be covered. Surface state properties of topological crystalline insulators will be discussed briefly.

  8. Spatially-interactive biomolecular networks organized by nucleic acid nanostructures.

    PubMed

    Fu, Jinglin; Liu, Minghui; Liu, Yan; Yan, Hao

    2012-08-21

    Living systems have evolved a variety of nanostructures to control the molecular interactions that mediate many functions including the recognition of targets by receptors, the binding of enzymes to substrates, and the regulation of enzymatic activity. Mimicking these structures outside of the cell requires methods that offer nanoscale control over the organization of individual network components. Advances in DNA nanotechnology have enabled the design and fabrication of sophisticated one-, two- and three-dimensional (1D, 2D, and 3D) nanostructures that utilize spontaneous and sequence-specific DNA hybridization. Compared with other self-assembling biopolymers, DNA nanostructures offer predictable and programmable interactions and surface features to which other nanoparticles and biomolecules can be precisely positioned. The ability to control the spatial arrangement of the components while constructing highly organized networks will lead to various applications of these systems. For example, DNA nanoarrays with surface displays of molecular probes can sense noncovalent hybridization interactions with DNA, RNA, and proteins and covalent chemical reactions. DNA nanostructures can also align external molecules into well-defined arrays, which may improve the resolution of many structural determination methods, such as X-ray diffraction, cryo-EM, NMR, and super-resolution fluorescence. Moreover, by constraint of target entities to specific conformations, self-assembled DNA nanostructures can serve as molecular rulers to evaluate conformation-dependent activities. This Account describes the most recent advances in the DNA nanostructure directed assembly of biomolecular networks and explores the possibility of applying this technology to other fields of study. Recently, several reports have demonstrated the DNA nanostructure directed assembly of spatially interactive biomolecular networks. For example, researchers have constructed synthetic multienzyme cascades by

  9. Fabrication of nanostructured electrodes and interfaces using combustion CVD

    NASA Astrophysics Data System (ADS)

    Liu, Ying

    Reducing fabrication and operation costs while maintaining high performance is a major consideration for the design of a new generation of solid-state ionic devices such as fuel cells, batteries, and sensors. The objective of this research is to fabricate nanostructured materials for energy storage and conversion, particularly porous electrodes with nanostructured features for solid oxide fuel cells (SOFCs) and high surface area films for gas sensing using a combustion CVD process. This research started with the evaluation of the most important deposition parameters: deposition temperature, deposition time, precursor concentration, and substrate. With the optimum deposition parameters, highly porous and nanostructured electrodes for low-temperature SOFCs have been then fabricated. Further, nanostructured and functionally graded La0.8Sr0.2MnO2-La 0.8SrCoO3-Gd0.1Ce0.9O2 composite cathodes were fabricated on YSZ electrolyte supports. Extremely low interfacial polarization resistances (i.e. 0.43 Ocm2 at 700°C) and high power densities (i.e. 481 mW/cm2 at 800°C) were generated at operating temperature range of 600°C--850°C. The original combustion CVD process is modified to directly employ solid ceramic powder instead of clear solution for fabrication of porous electrodes for solid oxide fuel cells. Solid particles of SOFC electrode materials suspended in an organic solvent were burned in a combustion flame, depositing a porous cathode on an anode supported electrolyte. Combustion CVD was also employed to fabricate highly porous and nanostructured SnO2 thin film gas sensors with Pt interdigitated electrodes. The as-prepared SnO2 gas sensors were tested for ethanol vapor sensing behavior in the temperature range of 200--500°C and showed excellent sensitivity, selectivity, and speed of response. Moreover, several novel nanostructures were synthesized using a combustion CVD process, including SnO2 nanotubes with square-shaped or rectangular cross sections, well

  10. Nanostructured catalysts for organic transformations.

    PubMed

    Chng, Leng Leng; Erathodiyil, Nandanan; Ying, Jackie Y

    2013-08-20

    The development of green, sustainable and economical chemical processes is one of the major challenges in chemistry. Besides the traditional need for efficient and selective catalytic reactions that will transform raw materials into valuable chemicals, pharmaceuticals and fuels, green chemistry also strives for waste reduction, atomic efficiency and high rates of catalyst recovery. Nanostructured materials are attractive candidates as heterogeneous catalysts for various organic transformations, especially because they meet the goals of green chemistry. Researchers have made significant advances in the synthesis of well-defined nanostructured materials in recent years. Among these are novel approaches that have permitted the rational design and synthesis of highly active and selective nanostructured catalysts by controlling the structure and composition of the active nanoparticles (NPs) and by manipulating the interaction between the catalytically active NP species and their support. The ease of isolation and separation of the heterogeneous catalysts from the desired organic product and the recovery and reuse of these NPs further enhance their attractiveness as green and sustainable catalysts. This Account reviews recent advances in the use of nanostructured materials for catalytic organic transformations. We present a broad overview of nanostructured catalysts used in different types of organic transformations including chemoselective oxidations and reductions, asymmetric hydrogenations, coupling reactions, C-H activations, oxidative aminations, domino and tandem reactions, and more. We focus on recent research efforts towards the development of the following nanostructured materials: (i) nanostructured catalysts with controlled morphologies, (ii) magnetic nanocomposites, (iii) semiconductor-metal nanocomposites, and (iv) hybrid nanostructured catalysts. Selected examples showcase principles of nanoparticle design such as the enhancement of reactivity, selectivity

  11. Carbon nanostructures for orthopedic medical applications.

    PubMed

    Yang, Lei; Zhang, Lijuan; Webster, Thomas J

    2011-09-01

    Carbon nanostructures (including carbon nanofibers, nanostructured diamond, fullerene materials and so forth) possess extraordinary physiochemical, mechanical and electrical properties attractive to bioengineers and medical researchers. In the past decade, numerous developments towards the fabrication and biological studies of carbon nanostructures have provided opportunities to improve orthopedic applications. Therefore, the aim of this article is to provide an up-to-date review on carbon nanostructure advances in orthopedic research. Orthopedic medical device applications of carbon nanotubes/carbon nanofibers and nanostructured diamond (including particulate nanodiamond and nanocrystalline diamond coatings) are emphasized here along with other carbon nanostructures that have promising potential. In addition, widely used fabrication techniques for producing carbon nanostructures in both the laboratory and in industry are briefly introduced. In conclusion, carbon nanostructures have demonstrated tremendous promise for orthopedic medical device applications to date, and although some safety, reliability and durability issues related to the manufacturing and implantation of carbon nanomaterials remain, their future is bright.

  12. Nanostructured Diclofenac Sodium Releasing Material

    NASA Astrophysics Data System (ADS)

    Nikkola, L.; Vapalahti, K.; Harlin, A.; Seppälä, J.; Ashammakhi, N.

    2008-02-01

    Various techniques have been developed to produce second generation biomaterials for tissue repair. These include extrusion, molding, salt leaching, spinning etc, but success in regenerating tissues has been limited. It is important to develop porous material, yet with a fibrous structure for it to be biomimetic. To mimic biological tissues, the extra-cellular matrix usually contains fibers in nano scale. To produce nanostructures, self-assembly or electrospinning can be used. Adding a drug release function to such a material may advance applications further for use in controlled tissue repair. This turns the resulting device into a multifunctional porous, fibrous structure to support cells and drug releasing properties in order to control tissue reactions. A bioabsorbable poly(ɛ-caprolactone-co-D,L lactide) 95/5 (PCL) was made into diluted solution using a solvent, to which was added 2w-% of diclofenac sodium (DS). Nano-fibers were made by electrospinning onto substrate. Microstructure of the resulting nanomat was studied using SEM and drug release profiles with UV/VIS spectroscopy. Thickness of the electrospun nanomat was about 2 mm. SEM analysis showed that polymeric nano-fibers containing drug particles form a highly interconnected porous nano structure. Average diameter of the nano-fibers was 130 nm. There was a high burst peak in drug release, which decreased to low levels after one day. The used polymer has slow a degradation rate and though the nanomat was highly porous with a large surface area, drug release rate is slow. It is feasible to develop a nano-fibrous porous structure of bioabsorbable polymer, which is loaded with test drug. Drug release is targeted at improving the properties of biomaterial for use in controlled tissue repair and regeneration.

  13. Displacement Talbot lithography: an alternative technique to fabricate nanostructured metamaterials

    NASA Astrophysics Data System (ADS)

    Le Boulbar, E. D.; Chausse, P. J. P.; Lis, S.; Shields, P. A.

    2017-06-01

    Nanostructured materials are essential for many recent electronic, magnetic and optical devices. Lithography is the most common step used to fabricate organized and well calibrated nanostructures. However, feature sizes less than 200 nm usually require access to deep ultraviolet photolithography, e-beam lithography or soft lithography (nanoimprinting), which are either expensive, have low-throughput or are sensitive to defects. Low-cost, high-throughput and low-defect-density techniques are therefore of interest for the fabrication of nanostructures. In this study, we investigate the potential of displacement Talbot lithography for the fabrication of specific structures of interest within plasmonic and metamaterial research fields. We demonstrate that nanodash arrays and `fishnet'-like structures can be fabricated by using a double exposure of two different linear grating phase masks. Feature sizes can be tuned by varying the exposure doses. Such lithography has been used to fabricate metallic `fishnet'-like structures using a lift-off technique. This proof of principle paves the way to a low-cost, high-throughput, defect-free and large-scale technique for the fabrication of structures that could be useful for metamaterial and plasmonic metasurfaces. With the development of deep ultraviolet displacement Talbot lithography, the feature dimensions could be pushed lower and used for the fabrication of optical metamaterials in the visible range.

  14. Design, assembly, and evaluation of RNA-protein nanostructures.

    PubMed

    Ohno, Hirohisa; Osada, Eriko; Saito, Hirohide

    2015-01-01

    The use of RNA-protein interaction motifs (RNP motifs) to design and build nanoscale objects has the potential to expand the field of RNA nanotechnology. In principle, RNP motifs can be integrated easily into RNA nano objects, providing an alternative technique to increase the functional and structural complexities of the RNA. Investigating the design principles of RNP nanostructures will enable the construction of highly sophisticated biomacromolecular complexes such as ribosomes from scratch. As an initial step towards this goal, we designed and constructed triangular-like nanostructures by employing box C/D kink-turn (K-turn)-L7Ae RNP motifs. We showed that the K-turn RNA and the ribosomal protein L7Ae could form a nanostructure shaped like an equilateral triangle that consists of the three proteins attached to the tips of the RNA scaffold. The construction of the complex depends on L7Ae binding to the K-turn motifs in the RNA. The RNP motif allows the RNA to bend by approximately 60° at three positions to form a nanoscale triangle. Functional RNP triangles with desired protein modules at the three tips can be constructed in a modular manner. Here, we describe how to design, construct, and evaluate the RNP nanostructures.

  15. Supramolecular materials: Self-organized nanostructures

    SciTech Connect

    Stupp, S.I.; LeBonheur, V.; Walker, K.

    1997-04-18

    Miniaturized triblock copolymers have been found to self-assemble into nanostructures that are highly regular in size and shape. Mushroom-shaped supramolecular structures of about 200 kilodaltons form by crystallization of the chemically identical blocks and self-organize into films containing 100 or more layers stacked in a polar arrangement. The polar supramolecular material exhibits spontaneous second-harmonic generation from infrared to green photons and has an adhesive tape-like character with nonadhesive-hydrophobic and hydrophilic-sticky opposite surfaces. The films also have reasonable shear strength and adhere tenaciously to glass surfaces on one side only. The regular and finite size of the supramolecular units is believed to be mediated by repulsive forces among some of the segments in the triblock molecules. A large diversity of multifunctional materials could be formed from regular supramolecular units weighing hundreds of kilodaltons. 21 refs., 10 figs.

  16. Nanostructured Deep Carbon: A Wealth of Possibilities

    NASA Astrophysics Data System (ADS)

    Navrotsky, A.

    2012-12-01

    The materials science community has been investigating novel forms of carbon including C60 buckyballs, nanodiamond, graphene, carbon "onion" structures with a mixture of sp2 and sp3 bonding , and multicomponent nanostructured Si-O-C-N polymer derived ceramics. Though such materials are generally viewed as metastable, recently measured energetics of several materials suggest that this may not always be the case in multicomponent systems. Finely disseminated carbon phases, including nanodiamonds, have been found in rocks from a variety of deep earth settings. The question then is whether some of the more exotic forms of carbon can also exist in the deep earth or other planetary interiors. This presentation discusses thermodynamic constraints related to surface and interface energies, nanodomain structures, and compositional effects on the possible existence of complex carbon, carbide and oxycarbide nanomaterials at high pressure.

  17. Comparison of the structural and chemical composition of two unique micro/nanostructures produced by femtosecond laser interactions on nickel

    SciTech Connect

    Zuhlke, Craig A.; Anderson, Troy P.; Alexander, Dennis R.

    2013-09-16

    The structural and chemical composition of two unique microstructures formed on nickel, with nanoscale features, produced using femtosecond laser surface processing (FLSP) techniques is reported in this paper. These two surface morphologies, termed mounds and nanoparticle-covered pyramids, are part of a larger class of self-organized micro/nanostructured surfaces formed using FLSP. Cross-sections of the structures produced using focused ion beam milling techniques were analyzed with a transmission electron microscope. Both morphologies have a solid core with a layer of nanoparticles on the surface. Energy dispersive X-ray spectroscopy by scanning transmission electron microscopy studies reveal that the nanoparticles are a nickel oxide, while the core material is pure nickel.

  18. Key Physical Mechanisms in Nanostructured Solar Cells

    SciTech Connect

    Dr Stephan Bremner

    2010-07-21

    The objective of the project was to study both theoretically and experimentally the excitation, recombination and transport properties required for nanostructured solar cells to deliver energy conversion efficiencies well in excess of conventional limits. These objectives were met by concentrating on three key areas, namely, investigation of physical mechanisms present in nanostructured solar cells, characterization of loss mechanisms in nanostructured solar cells and determining the properties required of nanostructured solar cells in order to achieve high efficiency and the design implications.

  19. Broadband antireflective silicon nanostructures produced by spin-coated Ag nanoparticles

    PubMed Central

    2014-01-01

    We report the fabrication of broadband antireflective silicon (Si) nanostructures fabricated using spin-coated silver (Ag) nanoparticles as an etch mask followed by inductively coupled plasma (ICP) etching process. This fabrication technique is a simple, fast, cost-effective, and high-throughput method, making it highly suitable for mass production. Prior to the fabrication of Si nanostructures, theoretical investigations were carried out using a rigorous coupled-wave analysis method in order to determine the effects of variations in the geometrical features of Si nanostructures to obtain antireflection over a broad wavelength range. The Ag ink ratio and ICP etching conditions, which can affect the distribution, distance between the adjacent nanostructures, and height of the resulting Si nanostructures, were carefully adjusted to determine the optimal experimental conditions for obtaining desirable Si nanostructures for practical applications. The Si nanostructures fabricated using the optimal experimental conditions showed a very low average reflectance of 8.3%, which is much lower than that of bulk Si (36.8%), as well as a very low reflectance for a wide range of incident angles and different polarizations over a broad wavelength range of 300 to 1,100 nm. These results indicate that the fabrication technique is highly beneficial to produce antireflective structures for Si-based device applications requiring low light reflection. PMID:24484636

  20. Second harmonic generation from ZnO films and nanostructures

    NASA Astrophysics Data System (ADS)

    Larciprete, Maria Cristina; Centini, Marco

    2015-09-01

    Zinc oxide ZnO is a n-type semiconductor having a wide direct band gap (3.37 eV) as well as a non-centrosymmetric crystal structure resulting from hexagonal wurtzite phase. Its wide transparency range along with its second order nonlinear optical properties make it a promising material for efficient second harmonic generation processes and nonlinear optical applications in general. In this review, we present an extensive analysis of second harmonic generation from ZnO films and nanostructures. The literature survey on ZnO films will include some significant features affecting second harmonic generation efficiency, as crystalline structure, film thickness, surface contributes, and doping. In a different section, the most prominent challenges in harmonic generation from ZnO nanostructures are discussed, including ZnO nanowires, nanorods, and nanocrystals, to name a few. Similarly, the most relevant works regarding third harmonic generation from ZnO films and nanostructures are separately addressed. Finally, the conclusion part summarizes the current standing of published values for the nonlinear optical coefficients and for ZnO films and nanostructures, respectively.