| 1. |
- Chiragwandi, Zackary, 1968, et al.
(författare)
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Vortex rings in pure water under static external electric field
- 2005
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Ingår i: APPLIED PHYSICS LETTERS 87 (15): Art. No. 153109. - : AIP Publishing. ; 87(15):15, s. 1-3
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Tidskriftsartikel (refereegranskat)abstract
- The reproducible development of vortex rings in pure water under the action of a static external electric field is demonstrated. The phenomenon results from the electrochemical decomposition of water. Given the low conductivity of water in the absence of electrolyte, the field-driven buildup of hydroxide ions at the anode becomes essential to the proton release, which in turn is the result of the molecular O-2(g) evolution. Water recombination processes, which have protons flowing in a hydroxide background, as a key ingredient produce the phenomenon. (C) 2005 American Institute of Physics.
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| 2. |
- Persson, Clas Marcus, et al.
(författare)
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Electronic band-edge structure, effective masses, and optical absorption of Si1-xGex using an extended FPLAPW/VCA/LDA+U computational method
- 2006
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Ingår i: Brazilian journal of physics. - : Sociedade Brasileira de Fisica. - 0103-9733 .- 1678-4448. ; 36:2 A, s. 447-450
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Tidskriftsartikel (refereegranskat)abstract
- Electronic band-edge structure and optical properties of Si 1-xGex are investigated theoretically emloying a full-potential linearized augmented plane wave (FPLAPW) method. The exchange-correlation potential in the local density approximation (LDA) is corrected by an on-site Coulomb potential (i.e., within the LDA.+USIC approach) acting asymmetrically on the atomic-like orbitals in the muffin-tin spheres. The electronic structure of the Si1-xGex is calculated self-consistently, assuming a Td symmetrized Hamiltonian and a linear behavior of the valence-band eigenfunctions for Si, SiGe, and Ge with respect to Ge composition x, assuming randomly alloyed crystal structure, i.e., a "virtual-crystal like" approximation (VGA). We show that this approach yields accurate band-gap energies, effective masses, dielectric function, and optical properties of Si1-xGex. We perform absorption measurements showing the band-gap energy for x < 0.25.
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| 3. |
- Soliveres, S., et al.
(författare)
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Excess low frequency noise in single-wall carbon nanotube
- 2006
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Ingår i: Fluctuation and Noise Letters. - : WORLD SCIENTIFIC PUBL CO PTE LTD. - 0219-4775 .- 1793-6780. ; 6:1, s. L45-L55
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Tidskriftsartikel (refereegranskat)abstract
- Low frequency noise measurements have been performed on a single-wall carbon nanotube connected by Ti/Au electrodes. It has been found that the 1/f noise decreases when the measurements are undertaken under vacuum and when the nanotube is partially degassed, showing a correlation between the fluctuation inducing the 1/f noise and the presence of gases. We show that the 1/f noise sources are located at the metal/nanotube contacts. When the device is annealed under vacuum at 450K, some Lorentzian shapes are observable and can be related to nanotube defects or to strongly bound molecules. © World Scientific Publishing Company.
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| 4. |
- Willander, Magnus, 1948, et al.
(författare)
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Solid and soft nanostructured materials: fundamentals and applications
- 2005
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Ingår i: Microelectronics Journal. - : Elsevier BV. - 0026-2692. ; 36:11, s. 940-949
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Tidskriftsartikel (refereegranskat)abstract
- The scientific work worldwide on nanostructured materials is extensive as well as the work on the applications of nanostructured materials. We will review quasi two-, one- and zero-dimensional solid and soft materials and their applications. We will restrict ourselves to a few examples from partly fundamental aspects and partly from application aspects. We will start with trapping of excitons in semiconductor nanostructures. The subjects are: physical realizations, phase diagrams, traps, local density approximations, and mesoscopic condensates. From these fundamental questions in solid nanomaterials we will move to trapping of molecules in water using nanostructured electrodes. We will also discuss how to manipulate water (create vortices) by nanostructure materials. The second part deals with nanorods (nano-wires). Particularly we will exemplify with ZnO nanorods. The reason for this is that ZnO has: a very strong excitons binding energy (60 meV) and strong photon–excitons coupling energy, a strong tendency to create nanostructures, and properties which make the material of interest for both optoelectronics and for medical applications. We start with the growth of crystalline ZnO nanorods on different substrates, both crystalline (silicon, silicon carbide, sapphire, etc) and amorphous substrates (silicon dioxide, plastic materials, etc) for temperatures from 50 °C up to 900 °C. The optical properties and crystalline properties of the nanorods will be analyzed. Applications from optoelectronics (lasers, LEDs, lamps, and detectors) are analyzed and also medical applications like photodynamic cancer therapy are taken up. The third part deals with nano-particles in ZnO for sun screening. Skin cancer due to the exposure from the sun can be prevented by ZnO particles in a paste put on the exposed skin.
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