823 research outputs found
Unusual microstructure and mechanical properties of egg case of the bolas spider Mastophora corpulenta Banks (Araneae, Araneidae)
No full textSustainable and very-low-temperature wet-chemistry routes for the synthesis of crystalline inorganic nanostructures
No full textIn this chapter, selected low (T < 200 °C)-temperature wet-chemistry
routes for the synthesis of crystalline inorganic compounds are described and
reviewed, outlining their main features and application fi elds. In particular, the chosen
approaches are hydro/solvothermal synthesis, template-assisted approaches,
nucleation and growth in solution/suspension, microemulsion and miniemulsion.
The described synthetic strategies have been selected since all of them, once optimized
the experimental set-up and conditions, comply with the paradigms of green
chemistry, being based on low (or even room) temperature of processing, on low
chemical consumption (they are all bottom-up approach), in many cases having water
as solvent or dispersing medium. In this regard, environmentally friendly methodologies
for the controlled synthesis of inorganic nanostructures represent a stimulating
research playground, since the use of environmentally friendly, green, cost-effective
and technically sound approaches to inorganic crystalline nanostructures does not
necessarily imply to sacrifi ce the sample crystallinity, purity, and monodispersity
Chemical functionalization of inner walls of carbon nanotubes with long-chain aliphatic amines
No full textSynthesis of carbon nanotubes (CNTs) using porous anodic alumina membrane (PA) as template and the chemical functionalization of their inner walls is presented. The CNT were prepared by catalyst-free process using the pyrolysis of liquid aerosol of toluene: ethanol (1:1 v/v). The surface modification of the inner surface walls of CNT was performed using the gas phase synthesis by aliphatic amines (1,8-diaminooctane, DO). SEM, TEM and XPS analysis confirmed the morphology of prepared CNT inside of PA pores and their successful functionalization by amino groups. The presence and growth of interesting carbon nanoparticle inside CNT was observed during amination process. We hypothesized their origin as nanodiamonds formed as a result of the heat treatment in the presence of air that support etching mechanism and defects formation which acts as a diamond growth sites.Tariq Altalhi, Elena V. Basiuk, Juan Rizo, Vladimir A. Basiuk, Milena Ginic-Markovic, Stephen Clarke and Dusan Losi
Solvent-free covalent functionalization of multi-walled carbon nanotubes and nanodiamond with diamines: Looking for cross-linking effects
No full textTowards self-consistent plasma modelisation in presence of neoclassical tearing mode and sawteeth: effects on transport coefficients
No full textThe neoclassical tearing modes (NTM) increase the effective heat and particle radial transport inside the plasma, leading to a flattening of the electron and ion temperature and density profiles at a given location depending on the safety factor q rational surface (Hegna and Callen 1997 Phys. Plasmas 4 2940). In burning plasma such as in ITER, this NTM-induced increased transport could reduce significantly the fusion performance and even lead to a disruption. Validating models describing the NTM-induced transport in present experiment is thus important to help quantifying this effect on future devices. In this work, we apply an NTM model to an integrated simulation of current, heat and particle transport on JET discharges using the European transport simulator. In this model, the heat and particle radial transport coefficients are modified by a Gaussian function locally centered at the NTM position and characterized by a full width proportional to the island size through a constant parameter adapted to obtain the best simulations of experimental profiles. In the simulation, the NTM model is turned on at the same time as the mode is triggered in the experiment. The island evolution is itself determined by the modified Rutherford equation, using self-consistent plasma parameters determined by the transport evolution. The achieved simulation reproduces the experimental measurements within the error bars, before and during the NTM. A small discrepancy is observed on the radial location of the island due to a shift of the position of the computed q = 3/2 surface compared to the experimental one. To explain such small shift (up to about 12% with respect to the position observed from the experimental electron temperature profiles), sensitivity studies of the NTM location as a function of the initialization parameters are presented. First results validate both the transport model and the transport modification calculated by the NTM model
Solvent-free covalent functionalization of multi-walled carbon nanotubes and nanodiamond with diamines: Looking for cross-linking effects
No full textThe covalent functionalization of carbon nanomaterials with diamines is a way to enhance the mechanical strength of nanocomposites due to cross-linking effects, to form complex networks for nanotube-based electronic circuits, as well as is important for a number of biomedical applications. The main goal of the present work was to covalently functionalize pristine multi-walled carbon nanotubes and nanodiamond with three aliphatic diamines (1,8-diaminooctane, 1,10-diaminodecane and 1,12-diaminododecane) and one aromatic diamine (1,5-diaminonaphthalene), by employing a simple one-step solvent-free methodology, which is based on thermal instead of chemical activation. We looked for experimental evidences of cross-linking effects in the carbon nanomaterials synthesized by using solubility/dispersibility tests, atomic force microscopy, scanning and transmission electron microscopy, as well as Fourier-transform infrared spectroscopy and thermogravimetric analysis for additional characterization
Solvent-free functionalization of carbon nanotube buckypaper with amines
No full texttWe demonstrate the possibility of fast and efficient solvent-free functionalization of buckypaper(BP) mats prefabricated from oxidized multiwalled carbon nanotubes (MWCNTs-ox), by using threerepresentative amines of different structure: one monofunctional aliphatic amine, octadecylamine(ODA), one monofunctional aromatic amine, 1-aminopyrene (AP), and one aromatic diamine, 1,5-diaminonaphthalene (DAN). The functionalization procedure, which relies on the formation of amidebonds with carboxylic groups of MWCNTs-ox, is performed at 150–180◦C under reduced pressure andtakes about 4 h including auxiliary degassing. The amine-treated BP samples (BP-ODA, BP-AP and BP-DAN, respectively) were characterized by means of a variety of analytical techniques such as Fourier-transforminfrared and Raman spectroscopy, thermogravimetric and differential thermal analysis, scanning andtransmission electron microscopy, scanning helium ion microscopy, and atomic force microscopy. Thehighest amine content was found for BP-ODA, and the lowest one was observed for BP-DAN, with a possi-ble contribution of non-covalently bonded amine molecules in all three cases. Despite of some differencesin spectral and morphological characteristics for amine-functionalized BP samples, they have in commona dramatically increased stability in water as compared to pristine BP and, on the other hand, a relativelyinvariable electrical conductivity
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