Addition Of Copper Nanoparticles Research Articles

Improving anti-corrosion and mechanical properties of mild steel pipelines by using polyurea with nanoparticles

ASTM A106 B grade is used to manufacture seamless steel pipe, which can be used at high temperature, pressure, and hard environmental conditions for oil and gas supplies but suffers from corrosion. Polyurea is an organic coating that is resistant to moisture, UV light, and chemicals and has a high range of service temperatures. In this study, the effect of polyurea coating with the addition of copper nanoparticles was investigated for improvement of anti-corrosion and mechanical behavior in 3.5 % NaCl solution for A106 steel. Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) tests were performed to examine anticorrosion properties, Scanning Electron Microscopy (SEM) was used to examine quality coating, thickness, and distribution of copper nanoparticles. Wear, hardness, and tensile tests were performed to check mechanical properties. The corrosion rate decreases from 0.16264 mpy to 0.01376 mpy while coating resistance increases from 2.95 × 104 Ω cm2 to 2.474 × 105 Ω cm2. An increasing trend was observed during the tensile test for pure polyurea and pure polyurea with 2 % copper nanoparticles. i.e., 501 MPa and 536 MPa, respectively. Results showed pure polyurea and polyurea with copper nanoparticles on steel improve its anti-corrosion and mechanical properties significantly.

Novel short Agave americana based biocomposite and nanobiocomposites for automotive applications

Short fibers of Agave Americana (AA) was extracted from its plant leaf, was chemically treated with Ac2O, HCOOH, H2O2, KMnO4 and NaOH, and then characterized by Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermo-gravimetric/differential thermo-gravimetric (TGA/DTG), and field emission-scanning electron microscopy (FE-SEM). PVA stabilized copper nanoparticles from chemical reduction method was characterized using field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), powder X-ray diffraction (PXRD), Dynamic light scattering analysis (DLS), UV–visible absorption spectroscopy, Fourier Transform infrared (FT-IR) spectroscopy and Thermogravimetric analysis/differential thermogravimetry (TGA/DTG). Bio-composites (AA + Polyester Resin (PE) and hybrid nano bio-composites (AA + Polyester Resin (PE) + Cu) were prepared from the untreated and treated AA fibers and further characterized. The synergistic effect of chemical treatment on morphological (SEM), thermal (TGA/DTG), mechanical properties (flexural, tensile, impact and compressive strength) followed by % water absorption were examined. The average surface roughness values (Ra) of chemical treated fiber was identified to be in decreasing manner along with compression strength of biocomposite in the order of untreated (10.74 μm, 44.01 MPa) > NaOH (8.55 μm, 45.07 MPa) > HCOOH (3.49 μm, 24.10 MPa) Ac2O (3.24 μm, 22.10 MPa) > H2O2 (2.51um, 17.9 MPa) > KMnO4 (1.52 μm, 15.1 MPa) treated fibers. Subsequently, the addition of 2s@PVA led to reverse the order namely, the compressive strength of the bionanocomposites were Untreated (10.74 μm, 9.0 MPa) < NaOH (8.55 μm, 0.1 MPa) < HCOOH (3.49 μm, 3.6 MPa) < Ac2O (3.24 μm, 7.6 MPa) < H2O2 (2.51um, 13.3 MPa) < KMnO4 (1.52 μm, 44.1 MPa) treated fibers. Similarly, the biocomposite where the fibres were treated with NaOH, HCOOH were more rough and had, good interconnection between fiber/PE matrix along with enhanced mechanical properties. On addition of nanobiocomposite, only KMnO4 treated fiber composite possed significant mechanical properties. Therefore, mixing CuNPs@PVA with KMnO4 treated fibers led to significant boost to the mechanical properties and minimised the % water absorption properties when compared to the untreated AA/PE biocomposites. The KMnO4 treatment of the AA fiber and addition of copper nanoparticles caused the enhancement of thermal properties, tensile strength and flexural strength. But, these nanobiocomposites were observed to have low impact strength; while, H2O2 treated nanobiocomposites had highest impact strength. The chemical treatment of the AA fiber with NaOH, Ac2O and KMnO4 developed the water resistance of the respective biocomposites. All the nanobiocomposites with chemically treated AA fibers (except Ac2O) were found to have high water resistance. So, they can be used in automotive industry for non-structural applications.

Hippocampus and jejunum biochemical parameters related to physiological ageing of neurons in rats fed diets with copper nanoparticles and different fiber types

Abstract One of the more important factors responsible for synaptic dysfunction of neurons is a neurological ageing. It is a natural consequence of occurrence of biochemical pathways in cells, promoting oxidation processes, an increase in the amount of free oxygen radicals that damage DNA, disorders in calcium ion homeostasis, interactions between lipids of cell membranes, formation of neurofibrillary tangles and deposition of toxic protein deposits. Diet modifications can delay neurometabolism disorders that occur as a result of aging, as well as limit the development of neurodegenerative diseases. The aim of this study on rats was to verify the hypothesis regarding the effect of dietary addition of copper nanoparticles (CuNPs; instead of standard CuCO3) in combination with various dietary fibers on changes in hippocampus and jejunum biochemical parameters related to metabolic disorders appearing with neurological ageing in rats. Male rats were fed a control diet with containing fiber α-cellulose and a standard or enhanced content of Cu provided as CuCO3 (6.5 or 13 mg/kg diet). The diets of other groups were deprived of CuCO3 and the animals were fed diets supplemented with two CuNPs aforementioned doses, and additionally combined with four different types of dietary fiber: α-cellulose (control fiber), pectin, inulin or psyllium (Plantago psyllium). The addition of dietary CuNPs increased the level of acetylcholinesterase (AChE) and decreased the levels of Tau protein, glycosylated AChE (GAChE) and Ca/calmodulin dependent protein kinase II alpha (CAMK2α) in the examined organs. To sum up, both applied doses of CuNPs, 6.5 mg and 13 mg per kg of a diet, can beneficially modulate some important parameters describing metabolic and neurodevelopmental status in the hippocampal and small intestinal tissue of rats. With regard to the fiber type added to rats’ diet, the Plantago psyllium fiber strengthened the mentioned effects of copper nanoparticles. The observed effects should be confirmed in a model study of neurodegeneration.

Temporal overlapping effect of the pump–probe technique on rhodamine 6G with the addition of copper nanoparticles

Temporal overlapping effect of the pump–probe technique on rhodamine 6G with the addition of copper nanoparticles

Evaluation of tool wear during turning of Ti6Al4V alloy applying MQL technique with Cu nanoparticles diversified in terms of size

In case of hard-to-cut materials, as titanium alloy Ti6Al4V, eco-friendly cooling methods or their modifications are still being developed. Therefore, various types of nanofluids are applied in the cutting process to reduce friction in the cutting zone and thus heat accumulation in the tool corner. This paper presents an analysis of the selected tool wear indicators, as well as the wear mechanisms, after turning with various cooling/lubricating techniques, including: MQL with the addition of copper nanoparticles (CuNPs), dry machining and the MQL technique without nanoparticles. Four sizes of CuNPs were applied: 22 nm, 35 nm, 65 nm and 80 nm. Analysis of SEM images and maps of elemental distributions on the cutting edge working surfaces allowed to determine that the smallest sizes of copper nanoparticles introduced in the cutting fluid result in reduced tool flank wear, as well as the reduced width and depth of the crater wear on the rake face. With the smallest size of copper nanoparticles, a “ball bearing” and tribofilm formation effects were obtained, which prevented intense adhesive and abrasive wear. Turning, applying MQL + CuNPS 22 nm method resulted in a decrease of selected tool wear rates from 25.7% to 55% compared to effects reached during dry machining, and from 11.7% to 39.2% compared to effects of MQL turning without addition of nanoparticles to the cutting fluid.

INFLUENCE OF THE ADDITIVE OF COPPER NANOPARTICLES ON THE PROPERTIES OF DRILLING FLUIDS

Link for citation: Tretyak A.Ya., Krivosheev K.V., Bezmolitvenny D.I. Influence of the additive of copper nanoparticles on the properties of drilling fluids. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 43-49. In Rus. Relevance. Currently, drilling companies affect up to 30 % of productive time to combat differential grabs. The development of drilling fluids that contribute to the reduction of differential tacks is an urgent task. It is known that nanodisperse particles have a positive effect on the technological process of drilling wells, in this regard, the issue of developing nanostructured drilling fluids for drilling companies is in demand. Experimental studies have been carried out at the Department of Oil and Gas Engineering and Technology of the South-Russian State Polytechnic University (Novocherkassk Polytechnic University) and highly inhibited drilling fluids with the addition of nanodispersed copper with a concentration of up to 4 % and a particle size from 40 to 80 nm have been developed at the level of inventions. It has been experimentally established that the addition of nanoparticles of nanodispersed copper to highly inhibited drilling fluids improves rheological, lubricating and anti-seizure performance. Nanodispersed copper particles in the drilling fluid help to reduce the surface tension at the separation of the two phases – drilling column – filtration crust, which helps to reduce the probability of differential tacks. The aim of the purpose of the research is to study the properties of the developed highly inhibited water-based solutions with the addition of nanodispersed copper, as well as to study their rheological, filtration, lubricating and anti-seizure capabilities. Objects: highly inhibited drilling fluids and their main properties. Methods: experimental-analytical method for studying the addition of copper nanoparticles to the properties of the drilling fluid. Results. Laboratory studies of the effect of copper nanoparticle additives on the quality of the drilling fluid were carried out. The effect of dispersed copper nanoparticles on the main parameters of the drilling fluid was established.

Mechanical Behaviour of Aluminium Hybrid Composites Reinforced with: Rice Husk Ash - Silicon Carbide - Copper Nanoparticles

The mechanical behaviour of Al6063 alloy matrix composites reinforced with rice husk ash (RHA), silicon carbide (SiC) and copper nanoparticles (CuNP) has been investigated. Rice husk ash and silicon carbide mixed in fixed weight ratios of 3: 1 while copper nanoparticles were varied from 1 to 4 weight ratio to prepare hybrid reinforced Al6063 based composites using two-step stir casting and spin casting technique. Hardness measurement, tensile testing, impact toughness, optical and scanning electron microscopy were used to characterize the composites produced. It was observed that as the density increases with the increase in addition of copper nanoparticles, the porosity reduces. It was also observed that hardness increases with increase in copper nanoparticles addition. The ultimate tensile strength and impact toughness increased with increase in copper nanoparticles. The impact toughness of reinforced composites improved with increase in copper nanoparticles addition. The composition with 4 wt. % copper nanoparticles exhibited superior combination of properties that may be useful for design of components for automobile application.

The Addition of Copper Nanoparticles to Mineral Trioxide Aggregate for Improving the Physical and Antibacterial Properties

The physical and antibacterial properties of mineral trioxide aggregate (MTA) have been improved by adding copper nanoparticles (CuNP). The CuNP colloid was synthesized by reacting CuCl2·2H2O and NaBH4 as the reducing agent using C6H8O6 as the capping agent. The Cu(II) concentration was varied by 3.0, 6.0, and 9.0 mM to produce CuNP-3, CuNP-6, and CuNP-9 colloids, respectively. The CuNP colloids were characterized with a UV-Vis spectrophotometer and TEM. MTA was hydrated with CuNP at a mass-to-volume ratio of 2:1 to produce Cu-MTA-3, Cu-MTA-6, and Cu-MTA-9, respectively. All products were characterized with XRD and SEM-EDX. The compressive strength, pH, Ca ion release, and solubility were measured, and antibacterial activity was tested. The results showed a spherical shape of the synthesized CuNP with a particle size of ~28.08 nm. Adding CuNP-9 to hydrated MTA increased the compressive strength, pH, Ca ion release, and solubility, with the value of 4.78±0.38 MPa; 9.01±0.03; 1718±63 ppm, and 22.48±0.37%, respectively. The highest antibacterial activity occurred for Cu-MTA-9, with an inhibition zone of 10.15±0.47 mm against S. aureus and 11.93±1.16 mm against P. aeruginosa. The findings show a potential application of the product for endodontic materials containing antibacterial agents.

Superlubricity of TiN coating using glycerol with the addition of Cu nanoparticles

Superlubricity was achieved by the addition of copper nanoparticles (CuNPs) as an additive to glycerol, a sustainable lubricant, which was applied to TiN-coated steel that underwent ball-on-flat reciprocating testing at an average contact pressure of 54.6 MPa. A coefficient of friction of ∼ 0.007 and a wear rate of 2.0 × 10–8 mm3/N m were achieved on the TiN coating when lubricated with glycerol + 0.1 wt% CuNPs at a sliding speed of 120 mm/s. XPS and Raman analysis suggested that a surface tribofilm containing CuNPs and a carbon-based film derived from the degradation of glycerol were deposited onto the contact area of the tribopairs, which effectively prevented the direct asperity contact between the steel ball and TiN-coated steel, enabling ultra-low friction.

Four-year effects of copper-nanoparticles on durability of resin-dentin interfaces

ObjectiveTo evaluate the effect of the addition of copper nanoparticles (CuNp) at different concentrations in an etch-and-rinse (ER) adhesive on the resin-dentin bond strength (μTBS), nanoleakage (NL) and presence of copper nanoparticles within the hybrid layer, in the immediate time (IM) and after 4 years of water storage (4 y). Material and methodsSeven experimental adhesive systems were formulated according to the concentration of CuNp (0 [control], 0.0075, 0.015, 0.06, 0.1, 0.5 and 1 wt%) added into the ER adhesive Ambar (FGM). The adhesives were applied to flat occlusal dentin surfaces after acid etching, and then a resin restoration was build-up. Specimens were longitudinally sectioned to obtain resin-dentin beam-like, which were used for evaluation of μTBS, NL and identification of presence of CuNp within the hybrid layer, at the IM and 4 y periods. ANOVA and Tukey's test were applied (α = 0.05). ResultsAddition of CuNp up to 0.5% in the adhesive system significantly increased the μTBS at IM (p < 0.05). After 4 y, copper-containing adhesives showed higher values of μTBS compare to control (p < 0.05). All adhesives showed a significant decrease in μTBS over time (p < 0.05). Significant decreases in the NL values were observed in the copper-containing adhesives in IM in comparison with control group (p < 0.05). After 4 y, all copper-containing adhesives showed significantly decreased NL values compare to control group. All adhesives showed a significant increase in NL over time (p < 0.05). Presence of copper within the hybrid layer was identified from 0.06% concentration even after 4 y of water storage. ConclusionThe addition of copper nanoparticles from 0.06% to 0.5% concentrations in an adhesive decreased the degradation of the adhesive interface, mainly because it is still present in the hybrid layer even after 4 years of water storage.

Structure and thermal properties of copper-polypropylene based nanocomposites

Polymer nanocomposites based on PP/Cu were obtained by the combining of ex-situ casting solution and hot pressing methods. The structure of polymer nanocomposites was characterized by XRD, SEM, EDS, AFM and FT-IR spectroscopy analysis. The thermal properties were analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the addition of copper nanoparticles to the PP polymer matrix increases the thermal stability of the polymer, and this thermal stability reaches its maximum value at 3% content of copper nanoparticles in the polymer. The reason for the increase in the thermal properties of nanocomposites is associated with the formation of a more perfect, dense and ordered structure of PP-based composites and the fact that nanoparticles play the role of a nucleus of crystallization for polymer matrices.

A Comprehensive Comparison in the Heat Transfer Performance of Pure Water-Based and Liquid Gallium-Based Hybrid Nanofluid Flows through a Minichannel, Using Two-Phase Eulerian–Eulerian Model

An in-house Fortran-based two-phase Eulerian–Eulerian solver is used to numerically study water-based and liquid metal gallium-based alumina-copper hybrid nanofluid forced convection flow through a wide rectangular mini channel in the laminar regime. The governing equations of liquid and solid phases are solved using sixth-order compact finite difference method. A parametric study involving Reynolds number, particle concentration and mixture ratios has been reported. From the study it is found that pure liquid gallium has 43.5% greater heat transfer enhancement compared to pure water. The ‘heat transfer performance parameter’ is used to analyze the heat transfer characteristics of all the nanofluids considered. Addition of copper nanoparticles into base fluid improves the heat transfer performance of liquid gallium by 10.73% and pure water by 46.9%, at 1% particle concentration and a Reynolds number of 100. A significant change in heat transfer performance is found with a change in the Reynolds number and particle concentration for water-based hybrid nanofluids compared to liquid gallium-based hybrid nanofluids. A Nusselt number correlation is proposed for alumina-copper water-based hybrid nanofluids. Present results are validated with numerical and experimental results available in the literature.

Effect of chitosan complexes on the bacterial community of cecum and productivity of broiler chickens

The search and development of natural biological additives that have a comprehensive effect as immunostimulants and improve digestion in poultry is relevant. This study was carried out at the Selection and Genetics Center “Zagorskoe EPH”. The control and experimental groups were formed of the 1-day-old Ross-308 cross broilers (35 heads in each). Six groups were formed. The broilers of the group No.1 (control) received basic feed (BF) with the addition of feed antibiotic Maxus. The group No.2 (control) received BF without feed antibiotic. The broilers of the group No.3 (experimental) received BF and the KH-1 chitosan complex. The group No.4 (experimental) received BF and the KHM chitosan complex with the addition of copper nanoparticles. The group No.5 (experimental) received BF and drinking preparation based on the KH-Aqua chitosan complex. The group No.6 (experimental) received BF and drinking preparation based on the KH-Aqua chitosan complex enriched with copper nanoparticles. The bacterial community of the gut cecum was analyzed using the molecular genetics method of next-generation sequencing (NGS). The addition of chitosan complexes (both supplemented with copper nanoparticles and in the drinking form) made it possible to obtain high livability of broilers with increased live body weight and decreased feed consumption per 1 kg of live body weight gain. The live body weight of 35-day-old broilers in the experimental groups was 2.96-5.70% higher than that of the control with a 5.86-8.23% decrease in feed consumption per 1 kg of live body weight gain. The results of NGS showed that the effect of chitosan complexes on the regulation of the composition of the microbiome of broilers’ cecum was predominantly positive. There was an up to 4.4-fold increase in the content of representatives of the normoflora, bacteria of the family Lactobacillaceae. The number of bacteria of genus Helicobacter, among which pathogens are often found, in the experimental groups was 2.6-33.3 times lower than in the group received antibiotics. So, the chitosan complexes were proved to be valuable supplements for poultry.

A study on the effect of the addition of copper nanoparticles on the tribological performance of Polyalphaolefin synthetic oil

Lubrication has become a powerful tool for minimizing friction and wear between mechanical contact surfaces. In order to improve the lubricating properties of base oil, nanoparticles are added. The present study investigates the effect of the addition of Cu Nanoparticles on the tribological behaviour of Polyalphaolefin (PAO4) synthetic oil. Tribo four-ball tester is used to determine the Friction Co-Efficient (COF) for pure PAO4 base oil and also with different concentrations (0.2, 0.4, 0.6, 0.8, 1.0, 1.2, and 1.4 wt%) of Cu nanoparticles. The wear surfaces are examined using a Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDX) and a Tool Makers Microscope. It is observed that Cu nanoparticles, when used as an oil additive, offer excellent anti-friction and anti-wear properties. When 1.0 wt% Cu nanoparticles are added to PAO4 oil, the COF (at the contact point) is lowered by 51.85 percent, and the wear scar diameter is reduced as well when compared to pure PAO4 oil.

Photocatalytic reduction of CO2 over LaMO3 (M: Fe, Co, Mn) /CuxO films

LaMO3/CuxO (M: Co, Mn, Fe) thin films were prepared in two steps. First, lanthanum perovskites were deposited by spin coating, and then a CuxO layer by Chemical Vapor Deposition. The X-ray diffraction characterization confirmed the formation of the crystalline perovskite phases. The topography of the films was observed by AFM analysis, where fine needles grains appeared in LaMnO3/CuxO and LaCoO3/CuxO perovskite films, being attributed to the CuxO layer. XPS characterization confirms the presence of a larger concentration of oxygenated species over the surface of the films; besides, it was possible to elucidate a mixed-valence state of copper nanoparticles. DR UV–vis analyses show a redshift displacement for LaCoO3 and LaMnO3 films with the addition of copper nanoparticles, related to improved light absorption. The evaluation of the CO2 photoreduction using the pure perovskite films was performed. The reaction showed that adsorbed oxygenated species (CO32−, OH−, among others) over the surface could hinder active sites causing low performance. Once films were decorated with CuxO nanoparticles, their performance was improved significantly in the formic acid evolution. Copper nanoparticles acted like active sites for CO2 reduction, promoting the separation of the charges.LaMnO3/CuxO films presented the higher production of formic acid associated with low presence of oxygenated species in the surface and the formation of scheme Z between semiconductors, allowing a better charge transfer.

The Role of 20-HETE, COX, Thromboxane Receptors, and Blood Plasma Antioxidant Status in Vascular Relaxation of Copper-Nanoparticle-Fed WKY Rats.

Recently, the addition of copper nanoparticles (NPs) in a daily diet (6.5 mg/kg) was studied in different animal models as a possible alternative to ionic forms. Male Wistar–Kyoto rats (24-week-old, n = 11) were fed with copper, either in the form of carbonate salt (Cu6.5) or metal-based copper NPs (NP6.5), for 8 weeks. The third group was fed with a half dose of each (NP3.25 + Cu3.25). The thoracic aorta and blood plasma was studied. Supplementation with NP6.5 decreased the Cu (×0.7), Cu/Zn-ratio (×0.6) and catalase (CAT, ×0.7), and increased Zn (×1.2) and superoxide dismutase (SOD, ×1.4). Meanwhile, NP3.25 + Cu3.25 decreased the Cu/Zn-ratio (×0.7), and CAT (×0.7), and increased the daily feed intake (×1.06). Preincubation with either the selective cyclooxygenase (COX)-2 inhibitor, or the non-selective COX-1/2 inhibitor attenuated vasodilation of rat thoracic aorta in the NP6.5 group exclusively. However, an increased vasodilator response was observed in the NP6.5 and NP3.25 + Cu3.25 group of rats after preincubation with an inhibitor of 20-hydroxyeicosatetraenoic acid (20-HETE) formation, and the thromboxane receptor (TP) antagonist. Significant differences were observed between the NP6.5 and NP3.25 + Cu3.25 groups of rats in: dietary intake, acetylcholine-induced vasodilation, and response to COX-inhibitors. Copper NPs in a standard daily dose had more significant effects on the mechanism(s) responsible for the utilization of reactive oxygen species in the blood plasma with the participation of prostanoids derived from COX-2 in the vascular relaxation. Dietary copper NPs in both doses modified vasodilation through the vasoconstrictor 20-HETE and the TP receptors.

Comparative Study of the Performance of Syngas-Fueled Carbon-Air Solid Oxide Fuel Cells Using Anodes Based on M-Doped CeO2 (M: Mo or Mo-Cu)

The use of syngas to feed solid oxide fuel cells (SOFCs) appears as an attractive alternative due to the possibility of being obtained from renewable sources such as biomass or from other solids of carbonaceous composition such as solid wastes through reforming reactions. The use of syngas in SOFCs has been studied in several previous works, directing the efforts to obtain an anode material with the appropriate electrocatalytic activity for the electrooxidation of syngas, able to tolerate carbon deposition and avoid sulfur poisoning [1]. The Ni-YSZ anode has been studied in the electrooxidation of syngas, being one of its advantages the catalysis of the water gas shift (WGS) reaction, generating more H2 with respect to CO and therefore improving the reaction kinetics [2]. One of the disadvantages presented by Ni-YSZ is the decrease of its performance in long term tests, due to the catalytic activity of Ni towards the reverse Boudouard reaction, so that carbon deposits block the triple phase boundaries (TPBs) of the anode [3]. CeO2-based materials are suitable for use as anodes in fuel cells fed with carbonaceous fuels due to their resistance to carbon deposition and sulfur poisoning [4, 5]. Recently it has been reported that the addition of molybdenum to CeO2 (Mo-doped CeO2 or CMO) confers catalytic activity to the carbon gasification reaction and an increase in the electrical conductivity of CeO2 [6]. Furthermore, it has been reported that the addition of copper nanoparticles to Mo-doped CeO2 increases about 10 times its electrical conductivity [7].Two nanomaterials for SOFC anodes were synthesized: Mo-doped CeO2 (CMO) and Cu,Mo-doped CeO2 (CMCuO). Both nanomaterials were synthesized by the combustion method with 10 wt.% total metal loading following the experimental procedures detailed in [6] and [7] correspondingly. The SOFCs were fabricated using a CMO-YSZ or CMCuO-YSZ composite as anode, a dense YSZ electrolyte and a LSM-YSZ cathode. Both SOFCs were fed with air at the cathode and humidified syngas at the anode (syngas + 3 vol.% H2O). The morphology of the SOFCs was studied by SEM, while the crystal structure and chemical stability of the materials were studied by XRD and EDS. The cells were characterized by EIS at OCV condition at different temperatures and syngas concentrations, while the cell performance was studied by linear sweep voltammetry.An ADIS analysis obtained from the EIS data for both fuel cells in Figure 1 clearly shows the presence of two phenomena at high frequencies related to the electrooxidation reactions of H2 and CO, these phenomena are sensitive to temperature changes, the differences in their charge transfer resistance values suggest that both reactions are carried out with different kinetics. The processes shown at low frequencies are related to diffusional limitations of each gas towards triple phase boundaries (TPBs), processes sensitive to changes in syngas concentration. Cell tests, operating at 800°C, showed a maximum electrical power density of 114 mW cm-2 at a current density of 208 mA cm-2 and a cell voltage of 549 mV for SOFC with CMO-YSZ anode and a maximum electrical power density of 120 mW cm-2 at a current density of 200 mA cm-2 and a cell voltage of 600 mV for SOFC with CMCuO-YSZ. The addition of copper to the CMO produces a slight improvement in the electrocatalytic activity of the material and reduced ohmic resistance by almost 50% (see Figure 2), however the ASR of the cell with CMCuO anodes does not show a substantial improvement with respect to the cell with CMO anodes. In addition, the ohmic resistance is the most important component in the ASR of both cells. SEM images of the cells after tests show that the CMCuO anode surface exhibits fractures and delamination of the material, which is not observed on the CMO anode surface. The X-ray diffraction spectra do not show the presence of new phases in any of the two anode materials so the delamination of the CMCuO anode is related to the differences in thermal expansion coefficients (TECs) of the materials whose value must be measured to prove this hypothesis.[1] T.M. Gür (2013) Chem. Rev., 113(8), 6179-6206.[2] O. Costa Nunez et al. (2005) J. Power Sources, 141(2), 241-249.[3] T.M. Gür et al. (2010) J. Power Sources, 195(4), 1085-1090.[4] I. Sreedhar et al. (2019), J. Electroanal. Chem., 848, 113315.[5] N. Mahato et al. (2015) Prog. Mater. Sci., 72, 141-337.[6] I. Díaz‐Aburto et al. (2019) Fuel Cells, 19(2), 147-159.[7] I. Díaz-Aburto et al. (2021), J. Electrochem. Sci. Technol., [epub ahead of print: https://doi.org/10.33961/jecst.2020.01571]. Figure 1

Thermal efficiency of flat plate thermosyphon solar water heater with nanofluids

BackgroundMany techniques are used to improve the thermal efficiency of flat plate solar collectors. The previous studies showed the high potentials of nanofluids for thermal efficiency improvement of flat plate solar collectors. MethodsIn this study, a numerical simulation is carried out to investigate the thermal efficiency of the flat plate thermosyphon solar water heater with different nanofluids. The water-aluminum oxide, water-copper oxide, water-copper, and water-titanium oxide nanofluids are used. The effects of different parameters, such as the volume fraction of nanoparticles, volumetric flow rate, solar radiation intensity, ambient temperature, and inlet temperature of water on the efficiency, useful energy, and mean temperature of absorber of the solar collector are investigated. FindingsThe results indicated that among the various nanoparticles, the addition of copper nanoparticles, followed by copper oxide, results in the greatest improvement in the efficiency and useful energy. The efficiency and useful energy increase with increasing the volumetric flow rate and volume fraction of nanoparticles. As the volume fraction of nanoparticles increases, the mean temperature of absorber decreases. As the ambient temperature increases from 20 °C to 40 °C, the efficiency increases by 5.5%. As the inlet temperature of water increases from 30 °C to 55 °C, the efficiency decreases by 15%. The efficiency decreases with increasing the solar radiation intensity.

Retraction: experimental evaluation on the tribological properties of cassia tora oil by the addition of copper nanoparticles

Retraction: experimental evaluation on the tribological properties of cassia tora oil by the addition of copper nanoparticles

Microstructure and Dielectric Properties of Polyaniline Doped with Copper Nanoparticles

Polyaniline (PANI) has been prepared by the oxidation method in order to fabricate it with various concentrations of copper nanoparticles (CuNPs) which produced using the reduction method. Various techniques have characterized pure PANI and PANI doped CuNPs composites, such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS), which were provided important information about the structure and morphology of the fabricated polymer nanocomposites. The properties of dielectric permittivity (έ), dielectric loss (ἔ) and electrical conductivity (σ_AC) properties were studied at room temperature versus a range of frequency (15-150) kHz. The results demonstrated that the addition of copper nanoparticles to polyaniline matrix increases the dielectric permittivity property and it decreases with increasing the frequency to reach a fixed value. So, the electrical conductivity of studied samples decrease with increasing the frequency.