Electrochemical Behavior of Carbon Nanoparticles (NPs) from Carbon Soot in Non-Aqueous Medium

Nanoparticles (NPs) generated by candle soot are of interest due to their potential applications. Because of their electronic properties, carbon-based zero-dimensional, one-dimensional, and two-dimensional nanomaterials such as graphene, fullerene, carbon nanotubes, and carbon nanofibers are extensively studied (1).However, synthesis of these nanomaterials is complex and expensive. Candle soot also contains fluorescent carbon NPswhich can be used for the preparation of fluorescent makers (2). The potential applications of candle soot NPs include energy storage [e.g., can be used for supercapacitor electrode material (3)], and conversion [fuel cells (4)]. Candle soot can be an excellent source of carbon NPs. In this presentation, we cover some challenges associated with carbon NPs, such as (a) instability of NPs due to agglomeration with time and increase in temperature and (b) separation and isolation of NPs. Thus, we focus on stabilization of NPs, isolation and characterization of NPs and to study electronic, optical, and electrochemical properties to determine whether they are promising candidate in the field of energy conversion.Candle soot formation depends on various parameters like substrate material, deposition time, flame temperature, wick dimension, and flame height (5). We developed a protocol for the collection of candle soot. With this proposed protocol, the carbon NPs generated from candle soot ranges from 50 nm to larger particle size which is confirmed by dynamic light scattering (DLS) technique shown in Fig. 1, and transmission electron microscope (TEM). We will include the electrochemical analysis such as investigation of oxidation/reduction processes to determine fundamental thermodynamic parameters of standard potential in organic solvents and aqueous solutions. References Jariwala, V.K. Sangwan, L.J. Lauhan, T.J. Marks, M.C. Harsam, Carbon nanomaterials for electronics, optoelectronics, photovoltaics, and sensing, Chem. Soc. Rev., 43 (2013), 2824-28.J. Campbell, M.J. Andrews, K.J. Stevenson, New nanotech from an ancient material: Chemistry demonstrations involving carbon-based soot, J. Chem. Educ., 89 (2012) 1280-1287.Zhang, D. Wang, B. Yu, F. Zhou, W. Liu, Candle soot as a supercapacitor electrode material, RSC. Adv., 4 (2014), 2586-2589.Khalakhan, R. Fiala, J. Laukova, P. Kus, A. Ostroverkh, M. Vaclavu, M. Vorokhta, I. Matolinova, V. Matolin., Candle Soot as an efficient support for proton exchange membrane fuel cell catalyst, Fuel Cell., 16 (2016) 652-655.N. Sahoo, B. kandasubramanian. An experimental design for the investigation of water repellent property of candle soot particles, Mater. Chem. Phys.,148 (2014), 134-142. Figure 1

The internationalization of the higher education sector in Algeria is one of the government’s most important priorities to catch up with the contemporary trends towards fostering internationalization in higher education in the twenty-first century globalized world. The U.S. Embassy in Algeria has added a valuable support instrument in this respect through its cultural exchange programs. Ongoing programs of scholarships for students’ mobility based on the strategies that aim at strengthening the universities’ international dimension have been created. The U.S. Embassy in Algiers provides different types of programs which are perceived as useful and important as they create further opportunities for the learners and the institutions to open up to the increased international environment of the higher education sector. Nevertheless, there seems to be major challenges and hindrances limiting its full potential as a strong tool for sustainable development and better higher education quality. As a strategic soft power tool with long-term impact, American cultural exchange programs seek to Americanize the world via spreading the American values, principles, and ideals abroad through impressing the program participators with the American culture and ideologies. In other words, the Americans assign to themselves the role of reinforcing and supervising peace and democracy in the world. To achieve that, they use the various cultural and educational exchange programs as a soft power mechanism to promote and emphasize the superiority of the American system, ideology, and identity in the world. The seriousness of these programs lies in the pre-selection of the participants. They select the youth with a special focus on their abilities to affect and influence others, along with the potentials they have to be future leaders in their countries to pursue and reinforce the American interests. Ideologies are associated with power structures. Indeed, American Policymakers rely on cultural exchange programs to fashion an international atmosphere that is supportive and conducive to the U.S. interests and values worldwide.

The main aim of this work was the synthesis and applications of functionalized-silica-supported gold nanoparticles. The silica-anchored functionalities employed, e.g. amine, alkynyl carbamate and sulfide moieties, possess a notable affinity with gold, so that they could be able to capture the gold precursor, to spontaneously reduce it (possibly at room temperature), and to stabilize the resulting gold nanoparticles. These new materials, potentially suitable for heterogeneous catalysis applications, could represent a breakthrough among the “green” synthesis of supported gold nanoparticles, since they would circumvent the addition of extra reducing agent and stabilizers, also allowing concomitant absorption of the active catalyst particles on the support immediately after spontaneous formation of gold nanoparticles. In chapter 4 of this thesis is also presented the work developed during a seven-months Marco Polo fellowship stay at the University of Lille (France), regarding nanoparticles nucleation and growth inside a microfluidic system and the study of the corresponding mechanism by in situ XANES spectroscopy. Finally, studies regarding the reparation and reactivity of gold decorated nanodiamonds are also described. Various methods of characterization have been used, such as ultraviolet-visible spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), X-ray Fluorescence (XRF), Field Emission Gun Scanning Electron Microscopy (SEM-FEG), X-ray Photoionization (XPS), X ray Absorption Spectroscopy (XAS).

Effects of low ambient pressure on the flame characteristics of ethanol−gasoline blended pool fire

Fire whirls can occur during urban fires, especially in intense fires in combustible building structures, and more often in forest or wildland fires. They are a special swirling diffusion flame characterized by significant enhancement in burning rates, flame heights and flame temperatures, along with a strong whirling motion of the flame. This whirling motion can pick up large firebrands and scatter them afar leading to spot fires. Many researchers have published experimental work on small- and medium-scale pool fire whirls and gaseous fuel fire whirls using split cylinders and various fixed-frame apparatus to investigate axial and tangential velocity profiles, axial and radial temperature distribution, burning rates, and flame heights. Likewise, several researchers have attempted to predict the experimental results of fire whirls using different modelling approaches and simulation software.In this paper, experiments were undertaken to study the dynamics of propane gas fire whirls in a small-scale, square-based, fixed-frame apparatus. Measurements of flame height and temperature profiles (both axial centerline and radial) were made for a low initial momentum burner of 76.2 mm internal diameter. The burner was operated at a volumetric flow rate of 6 dm3/min, which gave a heat release rate of 9.12 kW. Simulations using Fire Dynamics Simulator (FDS 6.6.0) and ANSYS Fluent 17.1 were performed to compare with the experimental measurements. Four separate mesh refinements were employed and four different sub-grid-scale (SGS) turbulence models were tested with FDS. The Deardorff, Wall-Adapting Local Eddy-viscosity (WALE), and dynamic Smagorinsky models, formed stable fire whirls for the two largest mesh refinements.The temperature profiles were overpredicted at the core of the flame with FDS and underpredicted with Fluent. The FDS simulation prematurely predicts the peak temperature for the axial centreline profile, whereas with Fluent the axial temperature profile matches the general trend of the experimental measurements.The visible flame height, determined through image processing, was approximately 0.88 ± 0.06 m, which corresponds to a measured temperature of ∼500°C. The 500°C temperature contour was used as a rough approximation of the flame height in the numerical simulations. It was found that with Fluent the 500°C contour grew until the fire whirl stabilized and reached the top of the hood at 1.6 m, clearly overpredicting the flame height. The height estimates based on the predicted 500°C contours show a strong dependence on the mesh resolution. This is primarily due to increased instability resulting in more mixing and spreading of the temperature for the coarser mesh size. However, the simulated flame heights show less dependence on the SGS turbulence models.

Experimental has been conducted on the effects of variations in the direction of the magnetic fields on flames characteristic of droplets combustion of coconut and palm oils. Two variations of the directions magnetic field N-N and S-N were used in this experiment by placing droplets of vegetable oils on the type K thermocouple between two permanent magnet rods. High-speed camera (120 frame per second) recorded the flames up to extinguished. The result showed that S-N magnetic fields affected on shorter burning time of coconut and palm oil, respectively 670 ms and 871 ms, with the highest temperature of 816.25 oC and 778 oC. The flame height produced by the S-N magnetic field in coconut oil is 34.36 mm shorter, ignitions delay time for all oils has faster than the N-N magnetic field. The strong magnetic field direction increases the oxygen concentrations and fuel molecules around the reaction zone, causing shorter combustion. This combustion produces different flame evolution, shape, height, temperature, and ignition delay times. Keywords: Flames evolution, Flames height, Flames temperature, Ignition delay, Vegetable oils.

Characteristics of microjet hydrogen diffusion flames stabilized near extinction are investigated numerically. Two-dimensional simulations are carried out using a detailed reaction mechanism. The effect of burner wall material, thickness, and thermal radiation on flame characteristics such as flame height and maximum flame temperature are studied. Results show that the flame stabilizes at lower fuel jet velocities for quartz burner than steel or aluminum. Higher flame temperatures are observed for low conductive burners, whereas the flame length increases with an increase in thermal conductivity of the burner. Even though thermal radiation has a minor effect on flame characteristics like flame temperature and flame height, it significantly influences the flame structure for low conductive burner materials. The burner tip and its vicinity are substantially heated for low conductive burners. The effect of burner wall thickness on flame height is significant, whereas it has a more negligible effect on maximum flame temperature. Variation in wall thickness also affects the distribution of H and HO2 radicals in the flame region. Although the variation in wall thickness has the least effect on the overall flame shape and temperature distribution, the structure near the burner port differs.

To study the effect of spacing on the flame propagation characteristics of polyethylene (PE)/metal sandwich insulation panels, an experimental platform was built to simulate the ejection of a flame from the opening of a building compartment of a high-rise building, and the effects of different spacings and the presence of hemming were investigated. The flame propagation characteristics were summarized from the three perspectives of the flame height, temperature change, and mass-loss rate. A temperature distribution model was established via the combination of the flame height and temperature change, and a mass-loss model was established to judge the degree of flame propagation. The experimental results are as follows. With the increase of the spacing, the flame height was found to first increase and then decrease, after which it finally reached stability. The front flame height reached the peak at the spacing of 6 cm, and the rear flame height reached the peak at the spacing of 9 cm. With the increase of the spacing, the flame temperature and mass-loss rate were found to first increase and then decrease, and both reached the peak values at the spacing of 6 cm. Moreover, the hemming of the thermal insulation panel was found to hinder the spread of flames to a certain extent.

BackgroundAs a radiosensitizing agent in magnetic resonance imaging (MRI), gadolinium is disadvantageous in that it confers a rather high toxicity and low longitudinal comfort time (r1). We hypothesized that gadolinium when combined with gold-coated iron oxide nanoparticles (NPs), might deliver better radiosensitization in MRI-based cancer theranostics. After being synthesized ligand/receptor RGD@Fe3O4-Au/Gd nanoparticles, they were characterized via some methods, such as visible–ultraviolet spectroscopy (UV–VIS), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscope (TEM). Using relaxometry, the parameters of contrast change in T1-weighted MRI and the rate of radiation sensitivity on cancerous (MCF-7, SK-BR-3 and MDA-MB-231 (and reference (MCF-10a) breast cell lines were investigated.ResultsThe presence of ultra-small iron oxide, gold, gadolinium, and RGD peptide as components of the RGD@Fe3O4-Au/Gd nanocomplex was confirmed by UV–visible, FTIR, EDX and XRD tests. With a size ranging from 4.124 nm (DLS) to 15 nm (TEM), these NPs exhibited a surface charge of –45.7 mV and a magnetic saturation of 3 emu/g. The concentrations of iron, gadolinium and gold samples in the nanocomplex were 1000, 1171 and 400 parts per million (ppm), respectively. In the relaxometry test, the rates of r2/r1 and r1 NPs were 1.56 and 23.5 mM−1 s−1. The dose increase factor for targeted (RGD@Fe3O4-Au/Gd) and non-targeted (Fe3O4-Au/Gd) NPs at 6 MV and 2 Gy was 89.1 and 59.1, respectively.ConclusionOwing to an enhanced signal-to-noise ratio (SNR), as confirmed by the MRI of RGD receptor-expressing MDA-MB-231 cells, RGD@Fe3O4-Au/Gd NPs were found to confer higher radiosensitization and an overall better performance as a novel radiosensitizer for MRI-based breast cancer theranostics than Fe3O4-Au/Gd nanocomplex.Graphical

Solvothermal hot injection synthesis of core-shell AgNi nanoparticles

This study presents the examination of zinc oxide (ZnO) nanoparticles (NPs) as potential contrast agents for microwave imaging (MWI). Polyethylene Glycol (PEG) with varying molecular weights (Mw) have been used to coat NPs. Characterisation of the colloidal dispersions have been recorded using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and Ultraviolet-Visible spectroscopy (UV-Vis). The dielectric characterisation of the aqueous colloidal suspensions was recorded over the microwave frequency range between 1–4 GHz, to assess effective contrast for microwave breast imaging applications. Our data shows zinc oxide NPs increase dielectric constant compared to the background medium. The PEGylation process further improved the suspension stability, which was confirmed by DLS and UV-Vis. ZnO-PEG achieved a significant increase in the dielectric constant and the increase was dependent on the different molecular weights of PEG.

The treatment of glioblastoma (GB) and neuroblastoma (NB) remains a challenge, as current chemotherapies are plagued with systemic toxicity, drug resistance, and inadequate blood–brain barrier (BBB) penetration. Therefore, novel therapeutic strategies with high specificity and the capacity to bypass the BBB are required. Chlorotoxin (CTX) selectively targets gliomas and neuroectodermal tumors, hence the use of CTX-targeted nanoparticles (NPs) represents a promising therapeutic approach for nervous system (NS) cancers. Bimetallic NPs composed of two metals such as gold-platinum NPs (AuPtNPs) exhibit enhanced anticancer properties compared to single-metal NPs, however their application in studying NS tumors has been relatively limited. CTX-functionalized monometallic gold NPs (CTX-AuNPs) and bimetallic gold-platinum NPs (CTX-AuPtNPs) were synthesized in this study. The NPs were characterized by Ultraviolet-Visible Spectroscopy (UV–vis), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Fourier Transform Infra-Red Spectroscopy (FTIR). Cytotoxicity of NPs was investigated in cancer (U87 and SH-SY5Y) and non-cancer (KMST-6) cells using the water-soluble tetrazolium (WST)-1 assay. The CTX-AuNPs and CTX-AuPtNPs had a core size of ∼5 nm. The CTX-AuPtNPs showed significant anticancer activity in U87 cells possibly due to the synergistic effects of combined metals. Findings obtained from this study demonstrated that CTX can be used to target NS cancers and that bimetallic NPs could be effective in their treatment. More studies are required to investigate the mechanisms of NPs toxicity, and further explore the hyperthermia treatment of NS cancer using the CTX-AuPtNPs.

Tunable surface adsorption and wettability of candle soot coated on ferroelectric ceramics

Eco-friendly synthesis of curcumin-loaded ZnO nanoparticles encapsulated in Pluronic F-127: Implications for bacterial and breast cancer therapies

Effect of liquid medium and laser processing parameters on the fabrication of carbon nanoparticles via pulsed laser ablation in liquid towards paper electronics