| 1. |
- Abdel-Karim, R., et al.
(författare)
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Electrodeposition and Characterization of Nanocrystalline Ni-Fe Alloys
- 2011
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; , s. 519274-
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Tidskriftsartikel (refereegranskat)abstract
- Nanocrystalline Ni-Fe deposits with different composition and grain sizes were fabricated by electrodeposition. Deposits with iron contents in the range from 7 to 31% were obtained by changing the Ni(2+)/Fe(2+) mass ratio in the electrolyte. The deposits were found to be nanocrystalline with average grain size in the range 20-30 nm. The surface morphology was found to be dependent on Ni(2+)/Fe(2+) mass ratio as well as electroplating time. The grains size decreased with increasing the iron content, especially in case of short time electroplating. Increasing the electroplating time had no significant effect on grain size. The microhardness of the materials followed the regular Hall-Petch relationship with amaximum value (762 Hv) when applying Ni(2+)/Fe(2+) mass ratio equal to 9.8.
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| 2. |
- Amin, Gul, et al.
(författare)
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Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method
- 2011
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Ingår i: Journal of Nanomaterials. - NY, USA : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; :269692
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C > 400mM) to lower (C < 25mM) C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the effect of growth temperature was seen as an influence on the aspect ratio.
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| 3. |
- Amin, Muhammad, 1979, et al.
(författare)
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Performance Enhancement of Carbon Nanomaterials for Supercapacitors
- 2016
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2016:Article Number: 1537269, s. 17-
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Forskningsöversikt (refereegranskat)abstract
- Carbon nanomaterials such as carbon nanotubes, carbon nanofibers, and graphene are exploited extensively due to their unique electrical, mechanical, and thermal properties and recently investigated for energy storage application (supercapacitor) due to additional high specific surface area and chemical inertness properties. The supercapacitor is an energy storage device which, in addition to long cycle life (one million), can give energy density higher than parallel plate capacitor and power density higher than battery. In this paper, carbon nanomaterials and their composites are reviewed for prospective use as electrodes for supercapacitor. Moreover, different physical and chemical treatments on these nanomaterials which can potentially enhance the capacitance are also reviewed.
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| 4. |
- Ayedh, Hussein, et al.
(författare)
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Acoustic phonons in nanowires with embedded heterostructures
- 2011
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2011
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined Acoustic phonons are studied in finite nanowires based on the elastic continuum model. The phonon dispersion relations are compared for different types of approximations both for pure nanowires and nanowire heterostructures including cubic and wurtzite materials. We find that the isotropic approximation highly underestimates the frequency of torsional modes. The impact of heterostructures on the lowest modes is rather weak and can be described by an average of the different structure parameters.
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| 5. |
- Bano, Nargis, et al.
(författare)
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Study of Radiative Defects Using Current-Voltage Characteristics in ZnO Rods Catalytically Grown on 4H-p-SiC
- 2010
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Ingår i: JOURNAL OF NANOMATERIALS. - : Hindawi. - 1687-4110 .- 1687-4129. ; 2010
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Tidskriftsartikel (refereegranskat)abstract
- High-quality ZnO rods were grown by the vapour-liquid-solid (VLS) technique on 4H-p-SiC substrate. The current transport mechanisms of the diodes at room temperature (RT) have been explained in term of the space-charge-limited current model based on the energy band diagram of ZnO rods/4H-p-SiC heterostructure. The tunneling mechanism via deep-level states was found to be the main conduction process at low-applied voltage but at trap-filled limit voltage VTFL all traps are filled and the space-charge-limited current conduction dominated the current transport. From the RT current voltage measurements, the energy of the deep level trap and the trap concentration were obtained as ∼0.24±0.02eV and 4.4×1018cm−3, respectively. The deep level states observed correspond to zinc interstitial (Zni ), responsible for the violet emission.
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| 6. |
- Bouhrara, M., et al.
(författare)
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Electromagnetic Properties of Inner Double Walled Carbon Nanotubes Investigated by Nuclear Magnetic Resonance
- 2013
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2013, s. 713475-
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear magnetic resonance (NMR) analytical technique was used to investigate the double walled carbon nanotubes (DWNTs) electromagnetic properties of inner walls. The local magnetic and electronic properties of inner nanotubes in DWNTs were analyzed using 25% (13) C enriched C-60 by which the effect of dipolar coupling could be minimized. The diamagnetic shielding was determined due to the ring currents on outer nanotubes in DWNTs. The NMR chemical shift anisotropy (CSA) spectra and spin-lattice relaxation studies reveal the metallic properties of the inner nanotubes with a signature of the spin-gap opening below 70 K.
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| 7. |
- Chey, Chan Oeurn, et al.
(författare)
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Synthesis of Fe-Doped ZnO Nanorods by Rapid Mixing Hydrothermal Method and Its Application for High Performance UV Photodetector
- 2014
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; , s. 524530-
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Tidskriftsartikel (refereegranskat)abstract
- We have successfully synthesized Fe-doped ZnO nanorods by a new and simple method in which the adopted approach is by using ammonia as a continuous source of OH- for hydrolysis instead of hexamethylenetetramine (HMT). The energy dispersive X-ray (EDX) spectra revealed that the Fe peaks were presented in the grown Fe-doped ZnO nanorods samples and the X-ray photoelectron spectroscopy (XPS) results suggested that Fe3+ is incorporated into the ZnO lattice. Structural characterization indicated that the Fe-doped ZnO nanorods grow along the c-axis with a hexagonal wurtzite structure and have single crystalline nature without any secondary phases or clusters of FeO or Fe3O4 observed in the samples. The Fe-doped ZnO nanorods showed room temperature (300 K) ferromagnetic magnetization versus field (M-H) hysteresis and the magnetization increases from 2.5 mu emu to 9.1 mu emu for Zn0.99Fe0.01O and Zn0.95Fe0.05O, respectively. Moreover, the fabricated Au/Fe-doped ZnO Schottky diode based UV photodetector achieved 2.33 A/W of responsivity and 5 s of time response. Compared to other Au/ZnO nanorods Schottky devices, the presented responsivity is an improvement by a factor of 3.9.
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| 8. |
- Duoc, Vo Thanh, et al.
(författare)
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New Design of ZnO Nanorod- and Nanowire-Based NO2 Room-Temperature Sensors Prepared by Hydrothermal Method
- 2019
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Ingår i: Journal of Nanomaterials. - : HINDAWI LTD. - 1687-4110 .- 1687-4129.
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Tidskriftsartikel (refereegranskat)abstract
- Room-temperature gas sensors are attracting attention because of their low power consumption, safe operation, and long-term stability. Herein, ZnO nanorods (NRs) and nanowires (NWs) were on-chip grown via a facile hydrothermal method and used for room-temperature NO2 gas sensor applications. The ZnO NRs were obtained by a one-step hydrothermal process, whereas the NWs were obtained by a two-step hydrothermal process. To obtain ZnO NW sensor, the length of NRs was controlled short enough so that none of the nanorod-nanorod junction was made. Thereafter, the NWs were grown from the tips of no-contact NRs to form nanowire-nanowire junctions. The gas-sensing characteristics of ZnO NRs and NWs were tested against NO2 gas at room temperature for comparison. The gas-sensing characteristics of the sensors were also tested at different applied voltages to evaluate the effect of the self-activated gas-sensing performance. Results show that the diameter of ZnO NRs and NWs is the dominant parameter of their NO2 gas-sensing performance at room temperature. In addition, self-activation by local heating occurred for both sensors, but because the NWs were smaller and sparser than the NRs, local heating thus required a lower applied voltage with maximal response compared with the NRs.
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| 9. |
- Gardner, James M., 1982-, et al.
(författare)
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Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy
- 2011
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2011, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal crystal templates were prepared by gravitational sedimentation of 0.5 micron polystyrene particles onto fluorine-doped tin oxide (FTO) electrodes. Scanning electron microscopy (SEM) shows that the particles were close packed and examination of successive layers indicated a predominantly face-centered-cubic (fcc) crystal structure where the direction normal to the substrate surface corresponds to the (111) direction. Oxidation of aqueous ferrous solutions resulted in the electrodeposition of ferric oxide into the templates. Removal of the colloidal templates yielded ordered macroporous electrodes (OMEs) that were the inverse structure of the colloidal templates. Current integration during electrodeposition and cross-sectional SEM images revealed that the OMEs were about 2 mu m thick. Comparative X-ray diffraction and infrared studies of the OMEs did not match a known phase of ferric oxide but suggested a mixture of goethite and hematite. The spectroscopic properties of the OMEs were insensitive to heat treatments at 300. C. The OMEs were utilized for photoassisted electrochemical oxidation. A sustained photocurrent was observed from visible light in aqueous photoelectrochemical cells. Analysis of photocurrent action spectra revealed an indirect band gap of 1.85 eV. Addition of formate to the aqueous electrolytes resulted in an approximate doubling of the photocurrent.
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| 10. |
- Hobzova, Radka, et al.
(författare)
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Embedding of Bacterial Cellulose Nanofibers within PHEMA Hydrogel Matrices: Tunable Stiffness Composites with Potential for Biomedical Applications
- 2018
-
Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2018
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial cellulose (BC) and poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels are both considered as biocompatible materials with potential use in various biomedical applications including cartilage, cardiovascular stent, and soft tissue engineering. In this work, the "ever-wet" process based on in situ UV radical polymerization of HEMA monomer in BC nanofibrous structure impregnated with HEMA was used, and a series of BC-PHEMA composites was prepared. The composite structures were characterized by ATR FT-IR spectroscopy, WAXD, SEM, and TEM techniques. The strategy of using densified BC material of various cellulose fiber contents was applied to improve mechanical properties. The mechanical properties were tested under tensile, dynamic shear, and relaxation modes. The final composites contained 1 to 20 wt% of BC; the effect of the reinforcement degree on morphology, swelling capacity, and mechanical properties was investigated. The biocompatibility test of BC-PHEMA composites was performed using mouse mesenchymal stem cells.
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| 11. |
- Ibupoto, Zafar Hussain, et al.
(författare)
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The Synthesis of NiO/TiO2 Heterostructures and Their Valence Band Offset Determination
- 2014
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; :928658
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a heterojunction based on p-type NiO/n-type TiO2 nanostructures has been prepared on the fluorine doped tin oxide (FTO) glass substrate by hydrothermal method. Scanning electron microscopy (SEM) and X-Ray diffraction techniques were used for the morphological and crystalline arrays characterization. The X-ray photoelectron spectroscopy was employed to determine the valence-band offset (VBO) of the NiO/TiO2 heterojunction prepared on FTO glass substrate. The core levels of Ni 2p and Ti 2p were utilized to align the valence-band offset of p-type NiO/n-type TiO2 heterojunction. The valence band offset was found to be similar to 0.41 eV and the conduction band was calculated about similar to 0.91 eV. The ratio of conduction band offset and the valence-band offset was found to be 2.21.
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| 12. |
- Jamshidi, Asgar, et al.
(författare)
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Efficiency Enhanced Colloidal Mn-Doped Type II Core/Shell ZnSe/CdS Quantum Dot Sensitized Hybrid Solar Cells
- 2015
-
Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129.
-
Tidskriftsartikel (refereegranskat)abstract
- Colloidal Mn-doped ZnSe/CdS core/shell quantum dots (QDs) are synthesized for the first time and employed as a strategy to boost the power conversion efficiency of quantum dot sensitized solar cells. By using Mn-doping as a band gap engineering tool for core/shell QDs an effective improvement of absorption spectra could be obtained. The mid-states generated by a proper Mn content alleviate carrier separation and enhance the electron injection rate, thus facilitating electron transport to the TiO2 substrate. It is demonstrated that a device constructed with 0.25% Mn-doped ZnSe/CdS leads to an enhancement of the electron injection rate and power conversion efficiency by 4 times and 1.3, respectively.
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| 13. |
- Kashif, M., et al.
(författare)
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Effect of Different Seed Solutions on the Morphology and Electrooptical Properties of ZnO Nanorods
- 2012
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2012:452407
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Tidskriftsartikel (refereegranskat)abstract
- The morphology and electrooptical properties of ZnO nanorods synthesized on monoethanolamine-based seed layer and KOH-based seed layer were compared. The seed solutions were prepared in monoethanolamine in 2-methoxyethanol and potassium hydroxide in methanol, respectively. Zinc acetate dihydrate was as a common precursor in both solutions. The nanorod-ZnOs were synthesized via the spin coating of two different seed solutions on silicon substrates followed by their hydrothermal growth. The scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and Raman studies revealed that the ZnO nanorods obtained from monoethanolamine-based seed layer had fewer defects, better crystals, and better alignment than those realized via KOH-based seed layer. However, the current-voltage (I-V) characteristics demonstrated better conductivity of the ZnO nanorods obtained via KOH-based seed layer. The current measured in forward bias was 4 mA and 40 mu A for ZnO-nanorods grown on KOH-based seed layer and monoethanolamine-based with the turn on voltage of approximately 1.5 V and 2.5V, respectively, showing the feasibility of using both structures in optoelectric devices.
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| 14. |
- Kovacic, Suzana, et al.
(författare)
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Design and Construction of a One- Dimensional DNA Track for an Artificial Molecular Motor
- 2012
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110.
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Tidskriftsartikel (refereegranskat)abstract
- DNA is a versatile heteropolymer that shows great potential as a building block for a diverse array of nanostructures. We present here a solution to the problem of designing and synthesizing a DNA-based nanostructure that will serve as the track along which an artificial molecular motor processes. This one-dimensional DNA track exhibits periodically repeating elements that provide specific binding sites for the molecular motor. Besides these binding elements, additional sequences are necessary to label specific regions within the DNA track and to facilitate track construction. Designing an ideal DNA track sequence presents a particular challenge because of the many variable elements that greatly expand the number of potential sequences from which the ideal sequence must be chosen. In order to find a suitable DNA sequence, we have adapted a genetic algorithm which is well suited for a large but sparse search space. This algorithm readily identifies long DNA sequences that include all the necessary elements to both facilitate DNA track construction and to present appropriate binding sites for the molecular motor. We have successfully experimentally incorporated the sequence identified by the algorithm into a long DNA track meeting the criteria for observation of the molecular motor's activity.
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| 15. |
- Larsson, Mikael, 1982, et al.
(författare)
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Nanocomposites of polyacrylic acid nanogels and biodegradable polyhydroxybutyrate for bone regeneration and drug delivery
- 2014
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2014, s. Art. no. 371307-
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Tidskriftsartikel (refereegranskat)abstract
- Biodegradable cell scaffolds and local drug delivery to stimulate cell response are currently receiving much scientific attention. Here we present a nanocomposite that combines biodegradation with controlled release of lithium, which is known to enhance bone growth. Nanogels of lithium neutralized polyacrylic acid were synthesized by microemulsion-templated polymerization and were incorporated into a biodegradable polyhydroxybutyrate (PHB) matrix. Nanogel size was characterized using dynamic light scattering, and the nanocomposites were characterized with regard to structure using scanning electron microscopy, mechanical properties using tensile testing, permeability using tritiated water, and lithium release in PBS using a lithium specific electrode. The nanogels were well dispersed in the composites and the mechanical properties were good, with a decrease in elastic modulus being compensated by increased tolerance to strain in the wet state. Approximately half of the lithium was released over about three hours, with the remaining fraction being trapped in the PHB for subsequent slow release during biodegradation. The prepared nanocomposites seem promising for use as dual functional scaffolds for bone regeneration. Here lithium ions were chosen as model drug, but the nanogels could potentially act as carriers for larger and more complex drugs, possibly while still carrying lithium.
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| 16. |
- Laxman, K., et al.
(författare)
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Improved sensitization of zinc oxide nanorods by cadmium telluride quantum dots through charge induced hydrophilic surface generation
- 2014
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2014
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on UV-mediated enhancement in the sensitization of semiconductor quantum dots (QDs) on zinc oxide (ZnO) nanorods, improving the charge transfer efficiency across the QD-ZnO interface. The improvement was primarily due to the reduction in the interfacial resistance achieved via the incorporation of UV light induced surface defects on zinc oxide nanorods. The photoinduced defects were characterized by XPS, FTIR, and water contact angle measurements, which demonstrated an increase in the surface defects (oxygen vacancies) in the ZnO crystal, leading to an increase in the active sites available for the QD attachment. As a proof of concept, a model cadmium telluride (CdTe) QD solar cell was fabricated using the defect engineered ZnO photoelectrodes, which showed ∼10% increase in photovoltage and ∼66% improvement in the photocurrent compared to the defect-free photoelectrodes. The improvement in the photocurrent was mainly attributed to the enhancement in the charge transfer efficiency across the defect rich QD-ZnO interface, which was indicated by the higher quenching of the CdTe QD photoluminescence upon sensitization.
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| 17. |
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| 18. |
- Liu, D. C., et al.
(författare)
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The Human Stratum Corneum Prevents Small Gold Nanoparticle Penetration and Their Potential Toxic Metabolic Consequences
- 2012
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129.
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles are being used inmultiple applications, ranging from biomedical and skin care products (e. g., sunscreen) through to industrial manufacturing processes (e. g., water purification). The increase in exposure has led to multiple reports on nanoparticle penetration and toxicity. However, the correlation between nanoparticle size and its penetration without physical/chemical enhancers through the skin is poorly understood-with studies instead focusing primarily on skin penetration under disrupted conditions. In this paper, we investigate the penetration and metabolic effects of 10 nm, 30 nm, and 60 nm gold nanoparticles within viable excised human skin after 24-hour exposure usingmultiphoton tomograph-fluorescence lifetime imaging microscopy. After 24 hour treatment with the 10, 30, and 60 nm gold nanoparticles, there was no significant penetration detected below the stratum corneum. Furthermore, there were no changes in metabolic output (total NAD(P) H) in the viable epidermis posttreatment correlating with lack of penetration of nanoparticles. These results are significant for estimating topical nanoparticle exposure in humans where other model systems may overestimate the exposure of nanoparticles to the viable epidermis. Our data shows that viable human skin resists permeation of small nanoparticles in a size range that has been reported to penetrate deeply in other skin models.
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| 19. |
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| 20. |
- Moberg, Tobias, 1986, et al.
(författare)
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Preparation and Viscoelastic Properties of Composite Fibres Containing Cellulose Nanofibrils : Formation of a Coherent Fibrillar Network
- 2016
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2016
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Tidskriftsartikel (refereegranskat)abstract
- Composite fibres with a matrix of poly(ethylene glycol) (PEG) and cellulose nanofibrils (CNF) as reinforcing elements were produced using a capillary viscometer. Two types of CNF were employed: one based on carboxymethylated pulp fibres and the other on TEMPO-oxidized pulp. Part of the latter nanofibrils was also grafted with PEG in order to improve the compatibility between the CNF and the PEG matrix. The nominal CNF-content was kept at 10 or 30 weight-%. The composite fibres were characterized by optical and scanning electron microscopy in addition to dynamic mechanical thermal analysis (DMTA). Evaluation of the storage modulus indicated a clear reinforcing effect of the CNF, more pronounced in the case of the grafted CNF and depending on the amount of CNF. An interesting feature observed during the DMTA-measurements was that the fibrils within the composite fibres appeared to forma rather coherent and load-bearing network which was evident even after removing of the PEG-phase (by melting). An analysis of the modulus of the composite fibres using a rather simple model indicated that the CNF were more efficient as reinforcing elements at lower concentrations which may be associated with a more pronounced aggregation as the volume fraction of CNF increased.
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| 21. |
- Mu, Liwen, et al.
(författare)
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Self-Lubricating Polytetrafluoroethylene/Polyimide Blends Reinforced with Zinc Oxide Nanoparticles
- 2015
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129.
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Tidskriftsartikel (refereegranskat)abstract
- ZnO nanoparticle reinforced polytetrafluoroethylene/polyimide (PTFE/PI) nanocomposites were prepared and their corresponding tribological and mechanical properties were studied in this work. The influences of ZnO loading, sliding load, and velocity on the tribological properties of ZnO/PTFE/PI nanocomposites were systematically investigated. Results reveal that nanocomposites reinforced with 3 wt% ZnO exhibit the optimal tribological and mechanical properties. Specifically, the wear loss decreased by 20% after incorporating 3 wt% ZnO compared to unfilled PTFE/PI. Meanwhile, the impact strength, tensile strength, and elongation-at-break of 3 wt% ZnO/PTFE/PI nanocomposite are enhanced by 85, 5, and 10% compared to pure PTFE/PI blend. Microstructure investigation reveals that ZnO nanoparticles facilitate the formation of continuous, uniform, and smooth transfer film and thus reduce the adhesive wear of PTFE/PI.
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| 22. |
- Mudimela, Prasantha R., et al.
(författare)
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Synthesis of carbon nanotubes and nanofibers on silica and cement matrix materials
- 2009
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; 2009
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Tidskriftsartikel (refereegranskat)abstract
- In order to create strong composite materials, a good dispersion of carbon nanotubes (CNTs) and nanofibers (CNFs) in a matrix material must be obtained. We proposed a simple method of growing the desirable carbon nanomaterial directly on the surface of matrix particles. CNTs and CNFs were synthesised on the surface of model object, silica fume particles impregnated by iron salt, and directly on pristine cement particles, naturally containing iron oxide. Acetylene was successfully utilised as a carbon source in the temperature range from 550 to 750 °C. 5-10 walled CNTs with diameters of 10-15nm at 600 °C and 12-20nm at 750 °C were synthesised on silica particles. In case of cement particles, mainly CNFs with a diameter of around 30nm were grown. It was shown that high temperatures caused chemical and physical transformation of cement particles. © 2009 Prasantha R. Mudimela et al.
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| 23. |
- Nasibulina, Larisa I., et al.
(författare)
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Effect of carbon nanotube aqueous dispersion quality on mechanical properties of cement composite
- 2012
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- An effect of the quality of carbon nanotube (CNT) dispersions added to cement on paste mechanical properties has been studied. High-quality dispersions of few-walled CNT (FWCNTs) were produced in two steps. First, FWCNTs were functionalized in a mixture of nitric and sulfuric acids (70wt. and 96wt., resp.) at 80°C. Second, functionalized FWCNTs were washed out by acetone to remove carboxylated carbonaceous fragments (CCFs) formed during CNT oxidation. Mechanical test results showed 2-fold increase in the compressive strength of the cement paste prepared from the dispersion of acetone-washed functionalized FWCNTs, which is believed to occur due to the chemical interaction between cement matrix and functional groups (-COOH and -OH). Utilisation of unwashed FWCNTs led to a marginal improvement of mechanical properties of the cement pastes, whereas surfactant-treated functionalized FWCNT dispersions only worsened the mechanical properties. Copyright © 2012 Larisa I. Nasibulina et al.
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| 24. |
- Noshad, Asma, et al.
(författare)
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Impact of AgNPs on seed germination and seedling growth : A focus study on its antibacterial potential against clavibacter michiganensis subsp. Michiganensis infection in solanum lycopersicum
- 2019
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of biogenic AgNPs on seed germination and seedling growth of Solanum lycopersicum. Treatment with silver nanoparticles (AgNPs) showed a significantly high germination rate and seedling growth compared to untreated seeds. Furthermore, its bactericidal effect against bacterial pathogen Clavibacter michiganensis subsp. michiganensis (cmm) infection in Solanum lycopersicum was also determined. Bacterial canker of tomato (BCT) caused by cmm results in reduced plant growth and production leading to considerable economic losses. Herein, fungal extracts of T. harzianum and A. fumigatus were used separately as a reducing agent to synthesize AgNPs of varying concentrations (0.088 mg/L, 0.176 mg/L, and 0.44 mg/L). Results suggested that the biosynthesized AgNPs not only worked as bactericide but also completely inhibited the incidence of cmm infection even at the lowest concentration of 0.088 mg/L under greenhouse conditions. Plants treated with AgNPs showed significantly enhanced growth parameters including plant height (cm), tomato yield/plant (g), fresh biomass (g), number of shoots/plant, root weight (g), and dry biomass (g). So, in order to reduce the toxic effects of chemical-based bactericides, biobased AgNPs are recommended, not only to control but also to prevent the bacterial infection in agriculture.
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| 25. |
- Saleemi, Mohsin, et al.
(författare)
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Classical Behavior of Alumina (Al2O3) Nanofluids in Antifrogen N with Experimental Evidence
- 2015
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- A nanofluid is a suspension containing nanoparticles in conventional heat transfer fluids. This paper reports on an investigation of alumina (Al2O3) nanoparticles in Antifrogen N, also called AFN, which is a popular antifreeze coolant consisting primarily of ethylene glycol and other additives to impede corrosion. The base carrier fluid is 50% by weight of water and 50% by weight of AFN. We systematically measured the nanomaterials and heat transfer data of nanofluids for four different size particles, namely, 20, 40, 150, and 250 nm alumina particles. The pH of all the nanofluids is adjusted to have a stable dispersion. The material characterizations include SEM and DLS particle measurements. We measured thermal conductivity, viscosity, and heat transfer coefficient in developing flow of the nanofluids. We observed that these nanofluids behave as any other classical fluids in thermally developing flow and classical heat transfer correlations can be used to completely describe the characteristics of these nanofluids.
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| 26. |
- Schröder, Elsebeth, 1966
(författare)
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Methanol Adsorption on Graphene
- 2013
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2013:Art. no. 871706
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption energies and orientation of methanol on graphene are determined from first-principles density functional calculations. We employ the well-tested vdW-DF method that seamlessly includes dispersion interactions with all of the more close-ranged interactions that result in bonds like the covalent and hydrogen bonds. The adsorption of a single methanol molecule and small methanol clusters on graphene is studied at various coverages. Adsorption in clusters or at high coverages (less than a monolayer) is found to be preferable, with the methanol C-O axis approximately parallel to the plane of graphene. The adsorption energies calculated with vdW-DF are compared with previous DFT-D and MP2-based calculations for single methanol adsorption on flakes of graphene (polycyclic aromatic hydrocarbons). For the high coverage adsorption energies, we also find reasonably good agreement with previous desorption measurements.
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| 27. |
- Sowwan, Mukhles, et al.
(författare)
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Growth of 2,2-Biimidazole-Based Nanorods on Mica Substrate
- 2010
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2010
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a one-dimensional single-stranded helix using the crystallization of silver (I) nitrate and 2,2-biimidazole has promising potential for use in the area of nanotechnology mainly because of its unique electrical properties and its structural similarity to naturally occurring nucleic acids. In this study, we report a new method for the deposition and growth of 2,2-biimidazole- based nanorods on mica substrates by employing a complex solution of silver nitrate (I) and 2,2-biimidazole. The morphology and electrical polarizability of the prepared nanorods are investigated by tapping mode atomic force microscopy (AFM) and noncontact electrostatic force microscopy (EFM). The experimental results show highly polarizable and singly separated nanorods oriented in three preponderant directions. In addition, we show that the active K+ ions on the mica surface are required for the formation of these nanorods. Additionally, these potassium ions are a critical factor in controlling the nucleation and morphology of nanostructures.
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| 28. |
- Sun, Hongfang, et al.
(författare)
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Synthesis and Properties of Red Mud-Based Nanoferrite Clinker
- 2019
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- Red mud, an industrial waste obtained from alumina plants, is usually discharged into marine or disposed into a landfill polluting the surrounding water, atmosphere, and soil. Thus, disposal of red mud is an environmental concern and it should be recycled in an effective way. Since red mud consists of iron- and aluminum-rich phases, it can potentially be processed into cementitious material and can be used for a construction purpose. This research investigated the synthesis of nanoferrite (NF) clinker by using red mud as a raw material through chemical combustion technology for potential use in cement-based composite. Before the synthesis of NF, red mud was characterized by using XRF, XRD, and SEM techniques. From characterization results, the stoichiometric ratio of raw materials was calculated and experimentally optimized. The sample was then tested at various temperatures (815, 900, 1000, and 1100 degrees C) to find the optimum synthesis temperature. Finally, the hydraulic activity of NF was verified and the contribution to mechanical properties was determined by replacing cement with NF at various substitution levels (0, 5, 10, and 20wt%). Test results showed that the optimum condition for the synthesis of NF was found when the ratio of CaCO3/red mud was 1.5 and the sintering temperature was 815 degrees C. The synthesized NF had an average diameter of 300nm, and the main composition was brownmillerite (C(4)AF) with distinct hydraulic reaction. When NF was used as a substitute of Portland cement in mortar, the flexural strength with a 5% replacement level improved by 15%. Therefore, it can be concluded that the synthesis of NF provides an alternative approach to recycle red mud and could significantly help in reducing environmental pollution.
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| 29. |
- Sun, Jie, 1977, et al.
(författare)
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Electrochemical Bubbling Transfer of Graphene Using a Polymer Support with Encapsulated Air Gap as Permeation Stopping Layer
- 2016
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110. ; 2016
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical bubbling transfer of graphene is a technique with high industrial potential due to its scalability, time- and cost-effectiveness, and ecofriendliness. However, the graphene is often damaged due to the turbulence and the trapped bubbles formed by the direct H2O and H+ permeation through the supporting polymer. We invent a graphene mechanical support of polyethylene terephthalate foil/plastic frame/poly(methyl methacrylate) sandwich, with an encapsulated air gap as the permeation stopping layer. The graphene damage is drastically reduced, as confirmed by the morphology and structural and electrical characterization, ultimately improving the controllability/reproducibility of the bubbling transfer of graphene and other two-dimensional materials.
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| 30. |
- Venkatesan, Dhanasekaran, et al.
(författare)
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Synthesis and Characterization of Sodium Bis(2-ethylhexyl) Sulfonsuccinate (AOT) Capped Pure and Mn-Doped CdS Nanoparticles
- 2012
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; , s. 492573-
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Tidskriftsartikel (refereegranskat)abstract
- CdS nanoparticles and thin films are well known for their excellent semiconducting properties. When transition metal ions are doped into the CdS, it exhibits magnetic properties in addition to semiconducting properties and they are termed as dilute magnetic semiconductors (DMSs). In this paper, we discuss the preparation of sodium bis(2-ethylhexyl) sulfonsuccinate (AOT) capped CdS nanoparticles and thin films doped with magnetic impurity Mn. Sodium bis(2-ethulexyl) sulfonsuccinate (AOT), capping agent promotes the uniform formation of nanoparticles. Optical characterizations are made using the UV-Vis spectrometer, PL, and FTIR. XRD shows the hexagonal structure of the CdS. SEM images and EDS measurements were made for the thin films. EPR shows the clear hyperfine lines corresponding to Mn2+ ion in the CdS nanoparticles.
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| 31. |
- Wrzesinska, A., et al.
(författare)
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Influence of the La3+, Eu3+, and Er3+ Doping on Structural, Optical, and Electrical Properties of BiFeO3 Nanoparticles Synthesized by Microwave-Assisted Solution Combustion Method
- 2019
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- In this study, nanocrystalline (18-28 nm) perovskite-like bismuth ferrite rare earth-doped powders (Bi0.9RE0.1FeO3, where RE = La (BLaFO), Eu (BEuFO), and Er (BErFO)) were obtained by microwave-assisted modification of solution combustion synthesis (SCS). The influence of high load La3+, Eu3+, and Er3+ doping on structural, optical, and electrical properties of BiFeO3 was investigated. It was found that rare earth doping along with fast phase formation and quenching significantly distorts the crystal cells of the obtained materials, which results in the formation of mixed rhombohedral- (R3c-) orthorhombic (Pbnm) crystal structures with decreased lengths of Bi-O and Fe-O bonds along with a decreasing radius size of doping ions. This promotes reduction of the optical band gap energy and suppression of ionic polarization at high frequencies and results in enhanced dielectric permittivity of the materials at 1 MHz.
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| 32. |
- Wu, Phillip, et al.
(författare)
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Toward 3D Integration of 1D Conductors: Junctions of InAs Nanowires
- 2011
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110.
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Tidskriftsartikel (refereegranskat)abstract
- A vision and one of the next challenges in nanoelectronics is the 3D integration of nanowire building blocks. Here we show that capillary forces associated with a liquid-air meniscus between two nanowires provides a simple, controllable technique to bend vertical nanowires into designed, interconnected assemblies. We characterize the electric nature of the junctions between crossed nanowires in a lateral geometry, which is one type of basic unit that can be found in interconnected-bent vertical nanowires. The crossed nanowire junction is capacitive in nature, and we demonstrate that one nanowire can be used to field effect gate the other nanowire, allowing for the possibility to develop extremely narrow conducting channels in nanowire planar or 3D electronic devices.
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| 33. |
- Yuwawech, Kitti, et al.
(författare)
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Effects of Two Different Cellulose Nanofiber Types on Properties of Poly(vinyl alcohol) Composite Films
- 2015
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- This work concerns a study on the effects of fiber types and content of cellulose nanofiber on mechanical, thermal, and optical properties polyvinyl alcohol (PVA) composites. Two different types of cellulose nanofibers, which are nanofibrillated cellulose (NFC) and bacterial cellulose (BC), were prepared under various mechanical treatment times and then incorporated into the PVA prior to the fabrication of composite films. It was found that tensile modulus of the PVA film increased with nanofibers content at the expense of its percentage elongation value. DSC thermograms indicate that percentage crystallinity of PVA increased after adding 2-4 wt% of the fibers. This contributed to the better mechanical properties of the composites. Tensile toughness values of the PVA/BC nanocomposite films were also superior to those of the PVA/NFC system containing the same fiber loading. SEM images of the composite films reveal that tensile fractured surface of PVA/BC experienced more ductile deformation than the PVA/NFC analogue. The above discrepancies were discussed in the light of differences between the two types of fibers in terms of diameter and their intrinsic properties. Lastly, percentage total visible light transmittance values of the PVA composite films were greater than 90%, regardless of the fiber type and content.
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| 34. |
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| 35. |
- Zhao, Yichen, et al.
(författare)
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Direct Determination of Spatial Localization of Carriers in CdSe-CdS Quantum Dots
- 2015
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal quantum dots (QDs) have gained significant attention due to their tunable band gap, simple solution processability, ease of scale-up, and low cost. By carefully choosing the materials, core-shell heterostructure QDs (HQDs) can be further synthesized with a controlled spatial spread of wave functions of the excited electrons and holes for various applications. Many investigations have been done to understand the exciton dynamics by optical characterizations. However, these spectroscopic data demonstrate that the spatial separation of the excitons cannot distinguish the distribution of excited electrons and holes. In this work, we report a simple and direct method to determine the localized holes and delocalized electrons in HQDs. The quasi-type-II CdSe-CdS core-shell QDs were synthesized via a thermolysis method. Poly(3-hexylthiophene) (P3HT) nanofiber and ZnO nanorods were selected as hole and electron conductor materials, respectively, and were combined with HQDs to form two different nanocomposites. Photoelectrical properties were evaluated under different environments via a quick and facile characterization method, confirming that the electrons in the HQDs were freely accessible at the surface of the nanocrystal, while the holes were confined within the CdSe core.
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