Magnetite (Fe3O4) nanoparticles prepared using hydrothermal approach were employed to study their potential application as magnetic resonance imaging (MRI) contrast agent. The hydrothermal process involves precursors FeCl2·4H2O and FeCl3 with NaOH as reducing agent to initiate the precipitation of Fe3O4, followed by hydrothermal treatment to produce nano-sized Fe3O4. Chitosan (CTS) was coated onto the surface of the as-prepared Fe3O4 nanoparticles to enhance its stability and biocompatible properties. The size distribution of the obtained Fe3O4 nanoparticles was examined using transmission electron microscopy (TEM). The cubic inverse spinel structure of Fe3O4 nanoparticles was confirmed by X-ray diffraction technique (XRD). Fourier transform infrared (FTIR) spectrum indicated the presence of the chitosan on the surface of the Fe3O4 nanoparticles. The superparamagnetic behaviour of the produced Fe3O4 nanoparticles at room temperature was elucidated using a vibrating sample magnetometer (VSM). From the result of custom made phantom study of magnetic resonance (MR) imaging, coated Fe3O4 nanoparticles have been proved to be a promising contrast enhanced agent in MR imaging. 相似文献
Direct ethanol fuel cells (DEFCs) offer a high degree of design flexibility, ranging from a single cell to a massive multi-cell that can be used in various applications, including portable devices, transportation, and stationary applications. Unfortunately, the most significant barrier to the commercialization of DEFCs is getting low-cost and ethanol permeability, high conductivity performance, and extended durability of polymer electrolyte membranes, as key components that highly influence the overall performance. In this paper, the recent progress in developing the polymer electrolyte membrane for the application of DEFCs has been comprehensively reviewed. Focusing on an updated modification of polymeric materials in the last 5 years, including Nafion-based membrane, polyvinyl alcohol-based membrane, polybenzimidazoles-based membrane, chitosan-based membrane, and sodium alginate-based membrane, as well as factors and challenges that affected the performance of polymer electrolyte membranes have been discussed, including the main characterization, catalyst selection, cell design, and work in membrane and cell performance of DEFCs. All discussion addresses the strategy to improve the performance of polymer electrolyte membranes in DEFCs in order to penetrate the commercialization stages. 相似文献
Topics in Catalysis - CO2 reforming of methanol for producing hydrogen was experimentally carried out in a fixed-bed reactor on 10%Ni/SiO2. The 10%Ni/SiO2 was completely reduced during H2... 相似文献
The moisture sorption isotherm (MSI) of lean beef and fat beef was experimentally determined. The experimental procedure used was that of the COST 90 project with some modifications to accelerate equilibration. The procedure was validated with the standard reference material microcrystalline cellulose. The MSI of the beef at the highest humidity range was obtained by accelerating equilibration with changes of salts, using a low water activity salt for some time. This procedure was reliable for beef samples but not for the fat samples. No significant changes were found for lean beef in the temperature range 5–40 °C. Three models, GAB, Peleg and Lewicki, were used to fit the experimental data. The best fit was obtained with the GAB equation. The fat MSI was determined at 5, 15 and 25 °C and it was best fitted with the Lewicki model. 相似文献
ABSTRACTA relatively better performance of jute fiber and yarn reinforced concrete composites can open up a wide access to application of natural resources in concrete strengthening. In order to achieve this goal, an experimental investigation on the flexural, compressive and tensile strengths of Jute Fiber Reinforced Concrete Composites (JFRCC) and Jute Yarn Reinforced Concrete Composites (JYRCC) has been conducted. To draw a specific conclusion, the mix ratios of 1:1.5:3 and 1:2:4 (by volume) of concrete have been maintained with incorporation of jute fiber and yarn in concrete mortar having different cut lengths with distinct volumetric ratios. Finally, a comparison of the JFRCC and JYRCC strength increments with respect to the plain concrete has been investigated. A significant increment of compressive, flexural and tensile strength was observed only for a short cut length having a low volumetric ratio, where JYRCC increment value was always found progressive. A far more regular arrangement and adequate mixture of JYRCC was also visualized compare to JFRCC in concrete mortar. All the principal increment values were found only in case of JYRCC with a mix ratio of 1:1.5:3. So, it can be concluded that the presence of jute yarn and more cement content can strengthen the concrete to a great extent. 相似文献
In this study, an amorphous poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) copolymer with a high yield strain (approximately 18 %) is proposed as a cladding material for highly flexible and reliable piezoelectric ribbon fibers. Macro preforms are fabricated for thermal drawing (TD) processes, in which a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) film is sandwiched between two electrically conductive composite sheets (carbon black (CB)/polypropylene (PP)). The piezoelectric device is cladded with the P(VDF-HFP) copolymer. The preform geometries and TD parameters are optimized to overcome the incompatibility of flow characteristics among P(VDF-HFP), P(VDF-TrFE), and CB/PP composite at the drawing temperature, yielding fibers of length more than 80 m through TD. After annealing and poling, the fiber produces approximately 5 V (peak-to-peak) under 2.5 % tensile strain and 0.5 V (peak-to-peak) under bending deformation, with a 5-mm radius of curvature. Furthermore, the piezoelectric fiber shows no severe degradation in the output voltage after 10000 cycles of bending deformation with 1-mm radius of curvature. The piezoelectric ribbon fiber developed herein has potential as a flexible tensile, pressure, or bending sensor fiber for wearable applications.
It is evident that the carbon-fiber-reinforced cementitious composites are being used in the structural and construction works owing to the synergetic action from two components viz. fiber and mortar matrix. Incorporation of a very nominal percentage of carbon fibers into a mortar mixture produces a strong and durable composite that leads the product of smart material properties. Flexural behavior of cement-based matrices carrying carbon fibers reinforcement of different percentage and size is studied in this paper. Influence of fiber content and length of the fiber is quantified using load–deflection curves. Specimens containing fiber of 0.0, 0.5, 1.0 and 1.5% with 3 mm (0.12 in.), 6 mm (0.36 in.), and their combination are prepared and tested. It is demonstrated that combination of 3 mm (0.12 in.) and 6 mm (0.36 in.) fibers enhances the bearing capacity to crack- and ultimate-stresses as well as the Young’s modulus of the fiber reinforced cement composites. The paper emphasizes the desired performances after the initiation of cracks and discusses the pre- and post-cracking load–deflection characteristics of the composites. 相似文献