| 1. |
- Akan, Rabia, et al.
(author)
-
Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures
- 2018
-
In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 8:23, s. 12628-12634
-
Journal article (peer-reviewed)abstract
- Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures.
|
|
| 2. |
- Baykal, A., et al.
(author)
-
Synthesis and Characterization of Dendrimer-Encapsulated Iron and Iron-Oxide Nanoparticles
- 2012
-
In: JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:5, s. 1541-1549
-
Journal article (peer-reviewed)abstract
- In this paper, a series of iron (Fe) containing nanoparticles were prepared by employing PAMAM (Poly(amidoamine), dendrimers with different generations (G0-G3) as templates and sodium borohydride as a reducing agent. The products have been characterized by TEM, FT-IR, XRD, VSM, TGA, and XPS. XRD analysis reveal low crystallinity of formed particles within the dendrimers, however, crystallinity of the nanoparticles was observed to increase with increasing generation of dendrimers. Dominant phases were determined as magnetite (Fe3O4 or maghemite, gamma-Fe2O3). XPS analysis revealed the chemical composition of nanoparticles as iron oxide which indicated the oxidation of Fe species subsequent to the reduction process, in agreement with XRD analysis. The magnetization curves have superparamagnetic nonhysteretic characteristic at lower fields and with nonsaturation characteristic at high fields. Magnetic evaluation of samples with the 20:1 molar ratio of Fe:PAMAM showed decreasing superparamagnetic character and decreasing saturation magnetisation with increasing generation of dendrimers.
|
|
| 3. |
- Holten-Andersen, Niels, et al.
(author)
-
Metals and the integrity of a biological coating : The cuticle of mussel byssus
- 2009
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 25:6, s. 3323-3326
-
Journal article (peer-reviewed)abstract
- The cuticle of mussel byssal threads is a robust natural coating that combines high extensibility with high stiffness and hardness. In this study, fluorescence microscopy and elemental analysis were exploited to show that the 3,4-dihydroxyphenyl-L-alanine (dopa) residues of mussel foot protein-1 colocalize with Fe and Ca distributions in the cuticle of Mytilus galloprovincialis mussel byssal threads. Chelated removal of Fe and Ca from the cuticle of intact threads resulted in a 50% reduction in cuticle hardness, and thin sections subjected to the same treatment showed a disruption of cuticle integrity. Dopa-metal complexes may provide significant interactions for the integrity of composite cuticles deformed under tension.
|
|
| 4. |
- Kurtan, U., et al.
(author)
-
Temperature dependent magnetic properties of CoFe2O4/CTAB nanocomposite synthesized by sol gel auto-combustion technique
- 2013
-
In: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:6, s. 6551-6558
-
Journal article (peer-reviewed)abstract
- A CoFe2O4/cetyl trimethylammonium bromide (CTAB) nanocomposite has been fabricated by a sol gel auto-combustion method. Characterization of the material revealed the composition of the crystalline phase as CoFe2O4 while FT-IR confirmed the presence of CTAB on the nanoparticles. From X-ray line profile fitting, average crystallite size was estimated to be 22 +/- 6 nm. SEM analysis showed a porous sheet-like morphology with internal nanosize grains of about 30 nm. The room temperature coercive field (He) of the CoFe2O4/CTAB nanocomposite was found to be 1045 Oe which is close to the previously reported room temperature values for bulk CoFe2O4. The H-c, was observed to decrease almost linearly with the square root of the temperature (root T) according to Kneller's law. From the linear fit of H-c versus root T, the zero-temperature coercivity (H-c0) and superparamagnetic blocking temperature (T-B) of the CoFe2O4/CTAB nanocomposite were found to be similar to 9.1 kOe and similar to 425 K, respectively. The remanence magnetization (M-r), the reduced remanent magnetization (M-r/M-s), and the effective magnetic anisotropy (K-eff) decrease with increasing temperature. The M-r/M-s value of 0.6 at 10 K higher than the theoretical value of 0.5 for non-interacting single domain particles with the easy axis randomly oriented suggests the CoFe2O4/CTAB nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner Wohlfarth model.
|
|
| 5. |
- Lobov, G. S., et al.
(author)
-
Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component
- 2017
-
In: Optical Materials Express. - 2159-3930. ; 7:1, s. 52-61
-
Journal article (peer-reviewed)abstract
- Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.
|
|
| 6. |
|
|
| 7. |
- Nikkam, Nader, 1978-, et al.
(author)
-
Effect of nanoparticle morphology on thermal conductivity and rheology of Zinc Oxide nanofluids
- 2012
-
Conference paper (peer-reviewed)abstract
- Nanofluids are stable dispersions of engineered nanometer-sized particles which have shown potential to enhance heat transfer properties. Nanoparticle morphology might influence the heat transport properties of the nanofluid. In this work our aim is to investigate the influence of nanoparticle morphology in the heat transfer and rheological properties of ZnO nanofluids. ZnO nanoparticles and nanorods were synthesized and dispersed in ethylene glycol, as the base fluid, to obtain nanofluids with different percentages of nanoparticle loading. Ultrasonic agitation was used for obtaining a stable suspension and the use of surfactants was avoided. The concentrations of ZnO nanofluids were varied between 1 wt% and 3 wt%. The physicochemical properties of nanofluids were characterized by using various techniques including particle size analyzer, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The thermal conductivity of prepared nanofluids were measured by Transient Hot Wire (THW) method and our finding on the physicochemical, transport and rheological properties of the ZnO nanofluids, containing nanoparticles with different morphology, are presented in detail.
|
|
| 8. |
|
|
