| 1. |
- Arve, K, et al.
(författare)
-
Analysis of the state and size of silver on alumina in effective removal of NOx from oxygen rich exhaust gas
- 2006
-
Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 0000-0000. ; 6:4, s. 1076-1083
-
Tidskriftsartikel (refereegranskat)abstract
- Ag/alumina catalysts with different silver contents for octane-SCR were prepared by impregnation and incipient wetness methods. Activity tests revealed that the decisive factor for high activity is not only a high dispersion of silver, but also the ability of the system to redisperse clustered silver. Determination of dispersion by TEM/HAADF and O-2-chemisorption experiments resulted in values close to each other even if the results were not directly comparable. This is suggested to be due to not complete silver reduction below 700 degrees C and the samples being very heterogeneous in terms of particle size, e.g., having a bimodal size distribution. Small charged Ag-n(delta+) clusters containing 2-8 silver atoms highly prevailed in the samples containing < 2 wt% Ag and exhibiting high octane-SCR activity In highly loaded Ag/alumina samples or those reduced and reoxidized at high temperature (> 400 degrees C), large metallic particles are stabilized, resulting in poor conversion of NOx to N-2.
|
|
| 2. |
- Balmes, Olivier, et al.
(författare)
-
Self-healing and self-organized gold nanoparticle films at a water/organic solvent interface
- 2006
-
Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 0000-0000. ; 6:1, s. 130-134
-
Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles (5 nm and 20 nm) have been synthesized and stabilized with mercaptoundecanol. These particles, although insoluble in water or common organic solvents, spread as a thin film at the liquid-liquid interface between a water phase and an organic phase. Films of these gold nanoparticles have been observed both by conventional transmission electron microscopy of deposited samples and by cryo-transmission electron microscopy of plunge-frozen samples. The film can be monolayered and extend over centimeter-sized areas. The particle films spontaneously re-assemble and self-organize at the interface when disrupted. This self-healing capacity of the film should make it possible to build a device for continuous production and deposition of the film.
|
|
| 3. |
- Balocco, C, et al.
(författare)
-
Microwave detection at 110 GHz by nanowires with broken symmetry
- 2005
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:7, s. 1423-1427
-
Tidskriftsartikel (refereegranskat)abstract
- By using arrays of nanowires with intentionally broken symmetry, we were able to detect microwaves up to 110 GHz at room temperature. This is, to the best of our knowledge, the highest speed that has been demonstrated in different types of novel electronic nanostructures to date. Our experiments showed a rather stable detection sensitivity over a broad frequency range from 100 MHz to 110 GHz. The novel working principle enabled the nanowires to detect microwaves efficiently without a dc bias. In principle, the need for only one high-resolution lithography step and the planar architecture allow an arbitrary number of nanowires to be made by folding a linear array as many times as required over a large area, for example, a whole wafer. Our experiment on 18 parallel nanowires showed a sensitivity of approximately 75 mV dc output/mW of nominal input power of the 110 GHz signal, even though only about 0.4% of the rf power was effectively applied to the structure because of an impedance mismatch. Because this array of nanowires operates simultaneously, low detection noise was achieved, allowing us to detect -25 dBm 110 GHz microwaves at zero bias with a standard setup.
|
|
| 4. |
- Bao, Jiming, et al.
(författare)
-
Optical properties of rotationally twinned InP nanowire heterostructures
- 2008
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:3, s. 836-841
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc blende InP nanowires. We have constructed the energy band diagram of the resulting multiquantum well heterostructure and have performed detailed quantum mechanical calculations of the electron and hole wave functions. The excitation power dependent blue-shift of the photoluminescence can be explained in terms of the predicted staggered band alignment of the rotationally twinned zinc blende/wurzite InP heterostructure and of the concomitant diagonal transitions between localized electron and hole states responsible for radiative recombination. The ability of rotational twinning to introduce a heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering.
|
|
| 5. |
- Barauskas, Justas, et al.
(författare)
-
Self-assembled lipid superstructures: Beyond vesicles and liposomes
- 2005
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:8, s. 1615-1619
-
Tidskriftsartikel (refereegranskat)abstract
- A unique set of nanoparlicle dispersions of self-assembled lipid mesophases with distinctive reversed cubic, hexagonal, and sponge phase structures has been prepared by use of original lipid combinations and a simple, generally applicable and scalable method. All key properties, particle size distributions, shape, phase structure, and stability, are controlled predictably and reproducibly. The results suggest the cross-disciplinary use of nonlamellar particle structures in science and technology as, for instance, biomimetics, in vivo drug delivery vehicles for diagnostic and therapeutic agents, protein crystallization matrices, and soft nanoporous materials.
|
|
| 6. |
- Bayer, K., et al.
(författare)
-
Targeted deposition of Au aerosol nanoparticles on vertical nanowires for the creation of nanotrees
- 2007
-
Ingår i: Journal of Nanoparticle Research. - : Springer Science and Business Media LLC. - 1572-896X .- 1388-0764. ; 9:6, s. 1211-1216
-
Tidskriftsartikel (refereegranskat)abstract
- Complex tree-like nanostructures with controlled morphology are becoming increasingly important for the development of nanoscale devices. The position of branches on III-V semiconductor nanotrees is determined by the distribution of Au seed particles. Here we report the dependence of the distribution of Au aerosol nanoparticles on nanowires on parameters including distance between wires, particle size, wire length, wire diameter, III-V material and particle charge. It was observed that different wire lengths and separation distances as well as different particle polarities have a significant effect on the resulting particle distribution while different wire diameters, particle diameters, materials and deposition voltages do not.
|
|
| 7. |
- Björk, Per, et al.
(författare)
-
Oligothiophene Assemblies Defined by DNA Interaction : From Single Chains to Disordered Clusters
- 2009
-
Ingår i: SMALL. - : Wiley. - 1613-6810 .- 1613-6829. ; 5:1, s. 96-103
-
Tidskriftsartikel (refereegranskat)abstract
- The organization of conjugated polyelectrolytes (CPEs) interacting with biomolecules sets conditions for the biodetection of biological processes and identity, through the use of optical emission from the CPE. Herein, a well-defined CPE and its binding to DNA is studied. By using dynamic light scattering and circular dichroism spectroscopy, it is shown that the CPE forms a multimolecule ensemble in aqueous solution that is more than doubled it? size when interacting with a small DNA chain, while single chains are evident in ethanol. The related changes in the fluorescence spectra upon polymer aggregation are assigned to oscillator strength redistribution between vibronic transitions in weakly coupled H-aggregates. An enhanced single-molecule spectroscopy technique that allows full control of excitation and emission light polarization is applied to combed and decorated;,DNA chains. It is found that the organization of combed CPE-lambda DNA complexes (when dry on the surface) allows considerable variation of CPE distances and direction relative to the DNA chain. By analysis of the polarization data. energy transfer between the polymer chains in individual complexes is confirmed and their sizes estimated.
|
|
| 8. |
- Björk, Per, et al.
(författare)
-
Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA
- 2005
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 5:10, s. 1948-1953
-
Tidskriftsartikel (refereegranskat)abstract
- DNA is the prototype template for building nanoelectronic devices by self-assembly. The electronic functions are made possible by coordinating electronic polymer chains to DNA. This paper demonstrates two methods for fabrication of aligned and ordered DNA nanowires complexed with conjugated polyelectrolytes (CPEs). The complex can be formed either in solution prior to stretching or after stretching of the bare DNA on a surface. Molecular combing was used to stretch the complexes on surface energy patterned surfaces, and PMMA for the bare DNA. Single molecular spectroscopy, in fluorescence, and microscopy, in atomic force microscopy, give evidence for coordination of the short CPE chains to the aligned DNA.
|
|
| 9. |
- Bordag, Michael, et al.
(författare)
-
Shear stress measurements on InAs nanowires by AFM manipulation
- 2007
-
Ingår i: Small. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 3:8, s. 1398-1401
-
Tidskriftsartikel (refereegranskat)abstract
- On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.
|
|
| 10. |
- Borgström, Magnus, et al.
(författare)
-
Precursor evaluation for in situ InP nanowire doping
- 2008
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19:44
-
Tidskriftsartikel (refereegranskat)abstract
- The use of tetraethyltin (TESn) and dimethylzinc (DMZn) as in situ n- and p-dopant precursors during particle-assisted growth of InP nanowires is reported. Gate voltage dependent transport measurements demonstrate that the nanowires can be predictably synthesized as either n- or p-type. These doped nanowires can be characterized based on their electric field response and we find that n- type doping scales over a range from 10(17) to 10(19) cm(-3) with increasing input TESn dopant molar fraction. On the other hand, the p-type doping using DMZn saturates at low levels, probably related to a strong increase in nanowire growth rate with increasing DMZn molar fractions. By optimizing growth conditions with respect to tapering, axial pn-junctions exhibiting rectifying behavior were fabricated. The pn-junctions can be operated as light emitting diodes.
|
|
