Nano-sized Carbon Particles Research Articles

Organic nanoparticles from different fuel blends: in vitro toxicity and inflammatory potential.

Despite the well-established link between particulate vehicle emissions and adverse health effects, the biological effects produced by ultrafine particles generated from fuel combustion need to be investigated. The biological impact of nano-sized organic carbon particles in the size range 3-7 nm, obtained from an engine fuelled with a standard diesel and four diesel fuels doped with additives of commercial interest is reported. Our data showed that the number of particles < 10 nm is to a very small extent reduced by diesel particle filters, despite its ability to trap micrometric and submicrometric particulates, and that there is a correlation between the additives used and the chemical characteristics of the nanoparticles sampled. The results show that the different nano-sized organic carbon particles induce cytotoxic and proinflammatory effects on the in vitro systems A549 (epithelial cells) and BEAS-2B (bronchial cells). All the fuels tested are able to induce the release of proinflammatory interleukins 8 and 6; moreover, the IC50 values show that the additives can increase the toxic potential of particles 10 times. Further analyses are therefore needed to better define the potential impact of organic ultrafine particles on human health.

Nonenzymatic test system for noninstrumental determination of antibodies to species-specific fibers of Yersinia pseudotuberculosis on the basis of nanosized carbon particles

Nonenzymatic test system for noninstrumental determination of antibodies to species-specific fibers of Yersinia pseudotuberculosis on the basis of nanosized carbon particles

Optical characterization of nano-sized organic carbon particles emitted from a small gasoline engine

The nano-sized organic carbon (NOC) particles emitted from a small gasoline engine were characterized using various ex situ optical techniques to assess their hazardous impact. The exhaust gas was sampled iso-kinetically by a quartz probe and passed through de-ionized water to gather the hydrophilic carbonaceous particulates as hydrosol. The hydrodynamic diameter of the particles ranged between 1.7 and 3.6nm at no load, with a mean diameter of 2.4nm. The particle size in the engine exhaust was found to increase at higher loads, which is attributed to coagulation of the particles. The chemical structure of the particles was analyzed using UV–vis and infra-red spectroscopy. Both the band gap energy and oscillator strength data evaluated from the UV–vis absorbance showed that the NOC particles contained polyaromatic hydrocarbon structures with three to five aromatic rings. Infra-red spectroscopy analysis further confirmed the presence of aliphatic and carbonyl functionalities in the aromatic structures of the particles. The fine size of the particles, their high number concentration for the type of the engine under study and their structural features, make the particles extremely hazardous for environment and health.

Effect of Agglomeration on the Toxicity of Nano-sized Carbon Black in Sprague-Dawley Rats

ObjectivesRecent studies have shown that nano-sized carbon black is more toxic than large respirable carbon black because of its higher surface area. However, it is not clear if carbon black made larger by agglomeration demonstrates decreased toxicity. The purpose of this study was to verify if agglomeration affects the toxicity of carbon black using three differently prepared nano-sized carbon black aerosols in nose-only inhalation chambers for 13 weeks.MethodsPrintex 90 was selected as a representative nano-sized carbon black. To generate aerosols of three different types of agglomerates, Printex 90 was dispersed in distilled water by three different methods: vortex, vortex+sonication, and vortex+sonication with dispersion in a stabilizer. Then, the three differently prepared solutions were aerosolized through venturi nozzles. Male Sprague-Dawley rats were exposed to Printex 90 aerosols in a nose-only exposure chamber for 6 h/d, 5 d/wk for 13 weeks at a concentration of approximately 9 mg/m3.ResultsNumbers of total cells in the bronchoalveolar lavage (BAL) fluid, macrophages, and polymorphonuclear leukocytes were increased and carbon black masses were clearly seen in BAL cells and lung tissues of rats exposed to Printex 90. However, few differences were found between the three differently agglomerated aerosols. In addition, there were no significant differences in other parameters, such as body weight, lung function or cytokine levels in BAL fluid following carbon black exposure.ConclusionsOnly mild to moderate respiratory effects were found in rats exposed to nano-sized carbon black at 9 mg/m3 for 13 weeks. Agglomeration did not affect the toxicity of nano-sized carbon particles.

Synthesis of polycrystalline γ-AlON powders by novel wet chemical processing

The synthesis of polycrystalline aluminum oxynitride (AlON) powders was investigated by the carbothermal reduction and nitridation (CRN) of amorphous precursor obtained by wet chemical processing. Co-precipitation processing was employed to achieve amorphous precursor from Al(NO3)3 solution dispersed by nanosized carbon particles, which was composed of Al(OH)3 and C particles homogeneously. The effects of the content of carbon black, pH value, and calcination temperature on formation of AlON phase were investigated by means of XRD, SEM and TEM, respectively. It was found that single phase AlON powder could be synthesized when the resultant precursors were calcined at 1750°C for 2 hours under flowing N2. Under optimal additional content of C (5.6wt%), the resultant AlON powders exhibited the primary particle size of about 1–3 μm with a specific surface area of 3.2 m2/g, which were superior to that of carbothermal reduction of immediate mixture of γ-Al2O3/C powders.

Increase in the rate of fuel combustion on addition of nanosized carbon particles

Nanosized carbon fuel additives were formed by ultrasonic crushing of graphitized films or by subjecting ethanol to an electric discharge. The obtained specimens of fuel were tested on a setup for rapid adiabatic compression. Under conditions of ultrasonic dispersion, a wide spectrum of particle sizes was observed, and their influence on the characteristics of combustion turned out to be insignificant. When ethanol was treated by an electric discharge, spherical or plane carbon nanoclusters and various transient shapes, as well as liquid components, were synthesized. The resulting fuel displayed a substantial increase in the rate of combustion.

Research Nanostructurized Carbon-Containing Catalysts on the тonkeris Clay Base by Physico-Chemical Methods

In this work are presented research results of physical and chemical characteristics of carbon-containing catalysts on Tonkeris clay base. A magnetic property of these catalysts was studied. It was established that the structure of the catalysts are contains а nano-sized carbon particles in a different morphology. Gydrocracking processes were investigated on the bases synthesized catalysts.

Synthesis of nano-structured 3C-SiC by carbothermal reduction of silicon bearing gel and carbon soot

Nano-sized 3C-SiC was synthesized using sol–gel method. The silica bearing sol was prepared using fumed silica and alkaline ethylene glycol which on hydrolysis resulted in a gel. The gel was mixed with nano-sized carbon particles (obtained from soot) and heat treated in 1300–1580 °C temperature range. The formation of 3C-SiC began at ~ 1400 °C and at 1580 °C it was observed to be the major phase while small amount of 2H-SiC was also present. The silicon carbide synthesized between 1400 and 1580 °C had particles in 30–50 nm range and crystallite size between 15 and 17 nm.

Preparation and Li Storage Properties of Hierarchical Porous Carbon Fibers Derived from Alginic Acid

One-dimensional (1D) hierarchical porous carbon fibers (HPCFs) have been prepared by controlled carbonization of alginic acid fibers and investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, nitrogen adsorption-desorption isotherms, and electrochemical tests toward lithium storage. The as-obtained HPCFs consist of a 3D network of nanosized carbon particles with diameters less than 10 nm and exhibit a hierarchical porous architecture composed of both micropores and mesopores. Electrochemical measurements show that HPCFs exhibit excellent rate capability and capacity retention compared with commercial graphite when employed as anode materials for lithium-ion batteries. At the discharge/charge rate of 45 C, the reversible capacity of HPCFs is still as high as 80 mA h g(-1) even after 1500 cycles, which is about five times larger than that of commercial graphite anode. The much improved electrochemical performances could be attributed to the nanosized building blocks, the hierarchical porous structure, and the 1D morphology of HPCFs.

Platelet adhesion and fibrinogen deposition in murine microvessels upon inhalation of nanosized carbon particles.

The translocation of nanoparticles in the lung toward effector organs via the circulation is considered an important direct pathway for systemic effects of nanoparticles after inhalation. Recently, we have reported that a moderate dose of systemically administered nanosized carbon black particles exerted thrombogenic effects in hepatic microvessels of healthy mice. This study addresses the questions of whether similar thrombogenic effects are also evoked upon inhalation of nanosized carbon particles (NCP) and whether NCP-induced hepatic platelet accumulation is associated with pulmonary or systemic inflammation. Two and 8 h after a 24-h exposure to either filtered air or to NCP, intravital fluorescence microscopy of the hepatic microcirculation was performed in C57Bl/6 mice. Parameters of pulmonary or systemic inflammatory response were determined in bronchoalveolar lavage and blood/plasma samples. Inhalative exposure to NCP caused platelet accumulation in the hepatic microvasculature, whereas leukocyte recruitment and sinusoidal perfusion did not differ from controls. Fibrinogen deposition was detected by immunohistochemistry in both hepatic and cardiac microvessels from NCP-exposed mice. In contrast, inhalation of NCP affected neither the plasma levels of proinflammatory cytokines nor blood cell counts. Moreover, the bronchoalveolar lavage data indicate that no significant inflammatory response occurred in the lung. Thus, exposure to NCP exerts thrombogenic effects in the microcirculation of healthy mice independent of the route of administration (i.e. inhalation or systemic intra-arterial administration). The NCP-induced thrombogenic effects are not liver specific, are associated with neither a local nor a systemic inflammatory response, and seem to be independent of pulmonary inflammation.

Carbothermal reduction and nitridation synthesis of silicon nitride by using solution combustion synthesized precursors

Carbothermal reduction and nitridation synthesis of Si3N4 was investigated by using precursor powders prepared by a solution combustion synthesis method. Glycine or urea (fuel), ammonium nitrate (oxidizer), silicic acid (Si source), and sucrose (major carbon source) were dissolved completely in water. This solution was dried and then heated to undergo the solution combustion synthesis reaction, resulting in a homogeneous mixture of nano-sized carbon and SiO2 particles, which was used as the precursor powder for the carbothermal reduction and nitridation synthesis of Si3N4. When the carbothermal reduction and nitridation reaction was carried out at 1,425–1,450 °C for 4 h, formation of Si3N4 can be detected only when the C/SiO2 weight ratio is greater than ~2.0. The Si3N4 yield increases rapidly as the C/SiO2 weight ratio is increased from ~2.0 to 2.8 and decreases with further increase in the C/SiO2 ratio. The α-phase content increases with increasing C/SiO2 weight ratio and decreases with increasing temperature. Depending on the C/SiO2 ratio, a Si3N4 yield of ~80 wt% and an α-phase content of ~90 wt% could be obtained.

On the interaction of nano-sized organic carbon particles with model lipid membranes

The cytotoxic character of atmospheric ultra-fine-particles (UFPs) has been reported in numerous, mainly epidemiological, investigations. However, the detailed mechanism, at the molecular level, leading to UFP cytotoxicity is not yet fully understood. To address this question, a better characterization of UFP toxicity in relation to chemical composition, surface area and particle number is needed. To follow this bottom-up approach, we have investigated the interaction of nano-sized organic carbon particles (NOCs), produced in ordinary combustion processes, with cell-sized unilamellar vesicles. These particles have a size in the 1–5 nm range and constitute an abundant fraction of the total carbon emission to the environment due to human activity. The investigation was performed by spectroscopically analyzing the chemical modifications of membrane lipid tails in optically trapped vesicles after exposure to NOCs. Our experimental outcomes demonstrate that they are able to induce oxidative damage to liposome membranes. This modification, in turn, leads to a change in membrane permeability, as observed by surface enhanced Raman scattering. It should be noticed that the method reported herein paves the way for a deeper comprehension of the interaction of nanomaterials with lipid membranes, in relation to both nanoparticles characteristics and membrane lipid composition.

Electrolytic Generation of Nano-Scale Carbon Phases with Framework Structures in Molten Salts on Metal Cathodes

An electrochemical study of mechanisms of electrodeposition of carbon solid phases from halide melts (Na,K|Cl; Na,K,Cs|Cl), saturated with carbon dioxide under an excessive pressure of up to 1.5 MPa, has been carried out in the temperature range 550 - 850 °C by cyclic voltammetry. It has been found that the cathode process occurs in three steps at sweep rates of less than 0.1 Vs−1, and its electrochemical-chemical-electrochemical (ECE) mechanism is suggested. It has furthermore been found that cathodic deposits contain nano-sized carbon particles of different forms and structure: blocks of amorphous carbon, crystalline graphite, carbon nanotubes (CNT), and nanofibres. The outer diameter of the tubes is 5 - 250 nm, and the internal diameter is 2 - 140 nm. A correlation between the product structure and yield against electrolysis conditions and regimes has been established.

Activation of the 3.47 μm Band by H Atom Irradiation of Carbon Grains Covered with a Water Ice Layer at 12 K

We present the first results of laboratory research on the processing of nano-sized carbon particles under simulated dense-medium conditions. The experiments aim to study the variations of the degree of hydrogenation of carbon particles covered with a water ice layer in response to H atom exposure. The effects of H atom processing have been studied by means of IR spectroscopy. The results show that the formation of C-H bonds in the aliphatic CH2 and CH3 functional groups does not take place. The activation of a band at 3.47 μm is observed. It is assigned to the C-H stretching vibration of tertiary sp3 carbon atoms. The band profile is compatible with that present in the spectrum of sources embedded in dense clouds. We propose that the carbon grain population, which is responsible for the interstellar aliphatic 3.4 μm band in diffuse regions, absorbs at 3.47 μm in dense clouds.

Nano-sized mesoporous carbon particles with bimodal pore system and semi-crystalline porous walls

Acetylene CVD carbon replication of a hierarchical pore silica-based material, Fe-UVM-7, is reported. The original template organization, which is based on the aggregation of mesoporous nanoparticles, is accurately replicated in the final carbon material: a bimodal porous carbon combining mesoporous nanoparticles and inter-particle textural-like pores which provide high surface area, a highly accessible pore system and semi-crystalline pore walls in the form of graphitic-like nanodomains is presented.

Laboratory simulation of the evolution of organic matter in dense interstellar clouds

AbstractLaboratory simulation of interstellar grain processing is a unique tool to better understand the nature and evolution of cosmic dust. In recent years this approach has been crucial to outline a new model of evolution of the aliphatic component of organic matter in the interstellar medium. Here, the results of a recent laboratory research on processing of nano-sized carbon particles by H atoms under simulated dense medium conditions are discussed. The experiments show that the formation of C-H bonds in the aliphatic CH2 and CH3 functional groups does not take place, while the activation of a band at 3.47 μm, due to the C-H stretching vibration of tertiary sp3 carbon atoms, is observed. These results indicate that the assumption about inhibition of aliphatic C-H bond formation in interstellar dense clouds is correct. Moreover, they suggest that carbon grains responsible for the interstellar aliphatic band at 3.4 μm in diffuse regions can contribute to the absorption observed at 3.47 μm in dense clouds.

Surface-enhanced Raman scattering study of nano-sized organic carbon particles produced in combustion processes

Surface-enhanced Raman scattering (SERS) has been employed for the first time to characterize nano-sized organic carbon (NOC) particles produced in ordinary combustion processes. Ag-coated glass microparticles, used as SERS substrate, provide a Raman scattering cross section enhancement up to five orders of magnitude, which allows sample investigation at low concentration level. The observed spectral features supply a deeper insight on the chemical properties of the investigated combustion product. In addition, the high sensitivity of the SERS technique might be useful to test and characterize the toxicity of NOC particles.

Fabrication and Evaluation of the Novel Elastomer Based Nanocomposite with Pressure Sensing Function

A novel organic/inorganic composite material which can work as a pressure sensor has been synthesized. This composite basically contains nano-sized carbon particles as conductive filler into an elastomer matrix to achieve pressure sensitive function. The superior pressure sensitive effect was showed at 0.88vol% of carbon particles while in the previous study the micro-sized carbon particle was required above 30vol%. In addition, nano-sized silica particles were added to reinforce electrical insulation properties and to improve the pressure sensing reliability of the composite. The addition of the surface modified silica improved better both the sensing performance and the mechanical strength than the composite containing non-modified silica particles. These polymer-based sensors have economical advantage due to low cost production regardless of the high performance.

Scanning-tunneling-microscopy of the formation of carbon nanocaps on SiC(0 0 0 −1)

Formation of nanosized cap structures on a thermally treated 6H–SiC(0 0 0 −1) substrate was investigated using atomic-resolution ultrahigh-vacuum scanning tunneling microscopy (UHV-STM). After removal of surface oxides by heating under UHV, clusters of carbon particles 1–2 nanometer in diameter were formed on the SiC surface at 1150 °C. Upon heating above 1150 °C, the carbon nanoparticles in the clusters merged, forming nanosized cap structures, which subsequently transformed into carbon nanotubes (CNTs). The clusters of nanosized carbon particles are thought to be the precursors of carbon nanocaps, and their sizes are strongly related to the sizes of CNT caps forming on the SiC surface.

Infrared analysis of nano organic particles produced in laminar flames

In this work we present the first infrared investigation of nano-sized organic carbon (NOC) particles produced in premixed laminar ethylene flames. We analyzed the chemical transformation of NOC when the combustible/oxidant ratio (C/O) passed from lean to slightly sooting conditions. We also demonstrate the increase of the aromatic character for samples under thermal treatment. The analysis of the infrared spectra clearly shows the persistence of this material after soot inception.