Comparative study of the modification of multi-wall carbon nanotubes by gamma irradiation and sonochemically assisted acid etching

Multi-walled carbon nanotubes (CNTs) have been treated with gamma irradiation in air or by using dilute acids (H 2SO 4/HNO 3) combined with 20 kHz ultrasound to compare their effects. The CNT microstructure has been investigated using transmission electron microscopy which revealed that both methods effectively modified the CNTs to overcome aggregation of the nanotubes, resulting in efficient dispersion in ethanol. The nature of the surface modifications was investigated using Raman and FTIR spectroscopies. The introduction of oxygenated species at the CNT surface was detected. At longer treatment times or high ultrasound intensities, the sonochemically assisted acid treatment showed the highest degree of reaction and functionalisation. Modification of the structure with γ-radiation with doses of 100 kGy or 200 kGy also resulted in a reduction of defects, attributed to an annealing and reorganisation process. The observed effects could be correlated with the time and intensity of the ultrasound used or the dose and dose rate of the γ-radiation. Both methods offer the possibility for processes with lower environmental inpact than those that currently exist. Our results also illustrate the importance of careful control over these experimental parameters if optimum results are to be obtained. </p

Ultrasound Promoted Synthesis and Properties of Chitosan Nanocomposites Containing Carbon Nanotubes and Silver Nanoparticles

A rapid and facile method to prepare functional chitosan nanocomposite films incorporating silver nanoparticles (AgNPs) has been developed using ultrasound assisted in-situ synthesis, dispersion and crosslinking. Addition of AgNPs and CNTs increased the mechanical strength and extensibility of polymeric chitosan nanocomposites. The films were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and infrared spectroscopy (IR). TEM showed that ultrasound produced more homogeneous dispersion of AgNPs and nanotubes as a result of breakage of CNTs bundles. Dielectric spectroscopy revealed that the real part of dielectric constant is found to increase with increase in temperature and frequency for both Chi/Ag and Chi/CNTs/Ag nanocomposite films. The conductivity of Chi/CNTs/Ag nanocomposite films was lower than when the CNTs were omitted

Comparative study of the modification of multi-wall carbon nanotubes by gamma irradiation and sonochemically assisted acid etching

Multi-walled carbon nanotubes (CNTs) have been treated with gamma irradiation in air or by using dilute acids (H 2SO 4/HNO 3) combined with 20 kHz ultrasound to compare their effects. The CNT microstructure has been investigated using transmission electron microscopy which revealed that both methods effectively modified the CNTs to overcome aggregation of the nanotubes, resulting in efficient dispersion in ethanol. The nature of the surface modifications was investigated using Raman and FTIR spectroscopies. The introduction of oxygenated species at the CNT surface was detected. At longer treatment times or high ultrasound intensities, the sonochemically assisted acid treatment showed the highest degree of reaction and functionalisation. Modification of the structure with γ-radiation with doses of 100 kGy or 200 kGy also resulted in a reduction of defects, attributed to an annealing and reorganisation process. The observed effects could be correlated with the time and intensity of the ultrasound used or the dose and dose rate of the γ-radiation. Both methods offer the possibility for processes with lower environmental inpact than those that currently exist. Our results also illustrate the importance of careful control over these experimental parameters if optimum results are to be obtained. </p

Fekete-Szegö Problem of Functions Associated with Hyperbolic Domains

In the field of Geometric Function Theory, one can not deny the importance of analytic and univalent functions. The characteristics of these functions including their taylor series expansion, their coefficients in these representations as well as their associated functional inequalities have always attracted the researchers. In particular, Fekete-Szegö inequality is one of such vastly studied and investigated functional inequality. Our main focus in this article is to investigate the Fekete-Szegö functional for the class of analytic functions associated with hyperbolic regions. Tofurther enhance the worth of our work, we include similar problems for the inverse functions of these discussed analytic functions

Eco-friendly synthesis and catalytic application of chitosan/gold/carbon nanotube nanocomposite films

Novel eco-friendly chitosan nanocomposite membranes containing gold nanoparticles and carbon nanotubes (CNTs) have been synthesized to produce reusable catalytic membranes.</p

Preparation, morphology and sonication time dependence of silver nanoparticles in amphiphilic block copolymers of PEO with polystyrene or PMMA

Composite materials comprising arrays of silver nanoparticles in amphiphilic copolymers have been prepared by sonochemically enhanced borohydride reduction of precursor silver nitrate (AgNO3). The precursor was incorporated into the cores of polymeric micelles formed from block copolymers of polystyrene (PS) or poly(methyl methacrylate) (PMMA) with poly(ethylene oxide) (PEO). The copolymers were synthesised with varying hydrophobic block lengths from a PEO macroinitiator by atom transfer radical polymerization (ATRP). UV/visible spectroscopy was used to confirm the formation of elemental silver and the effect of sonication time on the appearance of the silver nanoparticles was determined. The growth was faster than when gold nanoparticles are formed in comparable block copolymers. Nanoparticles formed in copolymers with PMMA blocks were more stable to agglomeration than when polystyrene was used. Electron microscopy revealed the morphology of the nanocomposites which confirmed that both block copolymers are vehicles for the formation of well-defined films containing nanoparticulate silver. However, AgNP formation shows some significant differences from previous reports of gold NP containing materials formed under similar conditions

Certain geometric properties of Mittag-Leffler functions

Abstract In this paper, some geometric properties of normalized Mittag-Leffler functions are investigated. We focus on starlikeness of order 2μ+η−1 $2\mu +\eta -1$ and convexity in the direction of imaginary axis. In addition, we study pre-starlikeness of Mittag-Leffler functions. The results are obtained by using the positivity technique