Solar Wind Turbulence and the Role of Ion Instabilities

International audienc

A dual-mode bandpass filter with enhanced capacitive perturbation

10.1109/TMTT.2003.815264IEEE Transactions on Microwave Theory and Techniques5181906-1910IETM

A modified microstrip circular patch resonator filter

10.1109/LMWC.2002.801135IEEE Microwave and Wireless Components Letters127252-254IMWC

Heat transfer performance of water-based tetrahydrofurfuryl polyethylene glycol-treated graphene nanoplatelet nanofluids

In order to improve the colloidal stability of graphene nanoplatelets (GNPs) in aqueous media, GNPs were first functionalized with tetrahydrofurfuryl polyethylene glycol in a quick electrophilic addition reaction method. To assess this, surface functionalization of the GNPs was analyzed by FTIR and Raman spectroscopy, and thermogravimetric analysis. In addition, the morphology of treated samples was investigated by transmission electron microscopy (TEM). As the second phase of the study, the thermophysical properties of samples were experimentally investigated. The third phase of the study involved experimentally measuring and numerically simulating the convective heat transfer coefficient and pressure drop of water-based TFPEG-treated GNP nanofluids (TGNP/water) at various weight concentrations and comparison with the base fluid in an annular heat exchanger. The results suggest that the addition of TGNP into the water improved the convective heat transfer coefficient dramatically. The pressure drop of prepared samples illustrated an insignificant variation as compared with the base fluid. The steady-state forced convective heat transfer experiments and simulation have confirmed the promising cooling capabilities of TGNP/water

Microwave-Assisted Synthesis of Highly-Crumpled, Few-Layered Graphene and Nitrogen-Doped Graphene for Use as High-Performance Electrodes in Capacitive Deionization

Capacitive deionization (CDI) is a promising procedure for removing various charged ionic species from brackish water. The performance of graphene-based material in capacitive deionization is lower than the expectation of the industry, so highly-crumpled, few-layered graphene (HCG) and highly-crumpled nitrogen-doped graphene (HCNDG) with high surface area have been introduced as promising candidates for CDI electrodes. Thus, HCG and HCNDG were prepared by exfoliation of graphite in the presence of liquid-phase, microwave-assisted methods. An industrially-scalable, cost-effective, and simple approach was employed to synthesize HCG and HCNDG, resulting in few-layered graphene and nitrogen-doped graphene with large specific surface area. Then, HCG and HCNDG were utilized for manufacturing a new class of carbon nanostructure-based electrodes for use in large-scale CDI equipment. The electrosorption results indicated that both the HCG and HCNDG have fairly large specific surface areas, indicating their huge potential for capacitive deionization applications

Microwave-assisted direct coupling of graphene nanoplatelets with poly ethylene glycol and 4-phenylazophenol molecules for preparing stable-colloidal system

Herein, microwave-assisted direct coupling of Graphene Nanoplatelets (GNP) with polymers including hydroxyl ( OH) groups such as poly ethylene glycol (PEG) and bio-molecules like 4-phenylazophenol (Azo) are investigated. Among different water-soluble polymers, PEG has received unique consideration due to its biocompatibility. Moreover, Azo-treated GNP can easily employ in long-term solar thermal storage. Thus, an electrophilic addition reaction under microwave irradiation is presented as an efficient procedure to functionalize GNP with Azo and PEG. In order to compare the activities of different catalysts under microwave irradiation, the direct coupling of GNP with Azo and PEG were performed in the presence of ZnCl2, FeCl2,TiCl4 and AlCl3, separately. The use of simple Lewis acids loading provides an electrophilic addition reaction in as little as 30 min, which provide a shortcut and prevent time-consuming and multiple steps approaches. Interestingly, PEG-treated GNP has no cross-linking of the flakes, which this allows the production of more dispersed GNP in aqueous media. Investigation of colloidal stability using particle absorbance measurement showed successful results in terms of stability with very low sediment. (C) 2015 Elsevier B.V. All rights reserved

A miniaturized dual-mode ring bandpass filter with a new perturbation

10.1109/TMTT.2004.839928IEEE Transactions on Microwave Theory and Techniques531343-348IETM

In vitroandin vivostudy of hazardous effects of Ag nanoparticles and Arginine-treated multi walled carbon nanotubes on blood cells: Application in hemodialysis membranes

One of the novel applications of the nanostructures is the modification and development of membranes for hemocompatibility of hemodialysis. The toxicity and hemocompatibility of Ag nanoparticles and arginine-treated multiwalled carbon nanotubes (MWNT-Arg) and possibility of their application in membrane technology are investigated here. MWNT-Arg is prepared by amidation reactions, followed by characterization by FTIR spectroscopy, Raman spectroscopy, and thermogravimetric analysis. The results showed a good hemocompatibility and the hemolytic rates in the presence of both MWNT-Arg and Ag nanoparticles. The hemolytic rate of Ag nanoparticles was lower than that of MWNT-Arg. In vivo study revealed that Ag nanoparticle and MWNT-Arg decreased Hematocrit and mean number of red blood cells (RBC) statistically at concentration of 100 μg mL-1. The mean decrease of RBC and Hematocrit for Ag nanoparticles (18% for Hematocrit and 5.8 × 1,000,000/μL) was more than MWNT-Arg (20% for Hematocrit and 6 × 1000000/μL). In addition, MWNT-Arg and Ag nanoparticles had a direct influence on the White Blood Cell (WBC) drop. Regarding both nanostructures, although the number of WBC increased in initial concentration, it decreased significantly at the concentration of 100 μg mL-1. It is worth mentioning that the toxicity of Ag nanoparticle on WBC was higher than that of MWNT-Arg. Because of potent antimicrobial activity and relative hemocompatibility, MWNT-Arg could be considered as a new candidate for biomedical applications in the future especially for hemodialysis membranes