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Surface characterization of polyester resins formulated with different cross-linking agents
Introduction Aluminum alloys are largely used due to their low density and good mechanical properties. Besides, the naturally formed oxide layer during aluminum exposure to the environment provides fair corrosion protection at low... more
Introduction Aluminum alloys are largely used due to their low density and good mechanical properties. Besides, the naturally formed oxide layer during aluminum exposure to the environment provides fair corrosion protection at low aggressive environments. However, the passivating oxide film formed does not present corrosion resistance in chloride containing environments, and surface treatments are necessary to protect the aluminum alloys surfaces. The surface treatments based on hexavalent chromium (Cr VI) are the most effective and have been used for many years with aluminum alloys used in the aeronautic industry due to their self-healing properties. However, due to the generation of toxic residues associated to these treatments, they are increasingly being prohibited. This has led to much research in search for alternative treatments that are environmentally friendly, mainly in the last decades [1-3]. The new treatments must also provide high corrosion resistance to the aluminum s...
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Multifunctional materials for energy conversion and storage could act as a key solution for growing energy needs. In this study, we synthesized nanoflower-shaped iron-nickel sulfide (FeNiS) over a nickel foam (NF) substrate using a facile... more
Multifunctional materials for energy conversion and storage could act as a key solution for growing energy needs. In this study, we synthesized nanoflower-shaped iron-nickel sulfide (FeNiS) over a nickel foam (NF) substrate using a facile hydrothermal method. The FeNiS electrode showed a high catalytic performance with a low overpotential value of 246 mV for the oxygen evolution reaction (OER) to achieve a current density of 10 mA/cm2, while it required 208 mV at 10 mA/cm2 for the hydrogen evolution reaction (HER). The synthesized electrode exhibited a durable performance of up to 2000 cycles in stability and bending tests. The electrolyzer showed a lower cell potential requirement for a FeNiS-Pt/C system (1.54 V) compared to a standard benchmark IrO2-Pt/C system (1.56 V) to achieve a current density of 10 mA/cm2. Furthermore, the FeNiS electrode demonstrated promising charge storage capabilities with a high areal capacitance of 13.2 F/cm2. Our results suggest that FeNiS could be us...
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Surface initiated PMMA brushes are a promising candidate to lubricate the silicon nitride–steel contact under oil lubricated conditions.
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Sodium-ion hybrid capacitors (SHCs) have attracted great attention owing to the improved power density and cycling stability in comparison with sodium-ion batteries. Nevertheless, the energy density (<100 Wh·kg-1) is usually limited by... more
Sodium-ion hybrid capacitors (SHCs) have attracted great attention owing to the improved power density and cycling stability in comparison with sodium-ion batteries. Nevertheless, the energy density (<100 Wh·kg-1) is usually limited by low specific capacity anodes (<150 mAh·g-1) and "kinetics mismatch" between the electrodes. Hence, we report a high energy density (153 Wh·kg-1) SHC based on a highly pseudocapacitive interface-engineered 3D-CoO-NrGO anode. This high-performance anode (445 mAh·g-1 @0.025 A·g-1, 135 mAh·g-1 @5.0 A·g-1) consists of CoO (∼6 nm) nanoparticles chemically bonded to the NrGO network through Co-O-C bonds. Exceptional pseudocapacitive charge storage (up to ∼81%) and capacity retention (∼80% after 5000 cycles) are also identified for this SHC. Excellent performance of the 3D-CoO-NrGO anode and SHC is owing to the synergistic effect of the CoO conversion reaction and pseudocapacitive sodium-ion storage induced by numerous Na2O/Co/NrGO nanointerfaces. Co-O-C bonds and the 3D microstructure facilitating efficient strain relaxation and charge-transfer correspondingly are also identified as vital factors accountable for the excellent electrochemical performance. The interface-engineering strategy demonstrated provides opportunities to design high-performance transition metal oxide-based anodes for advanced SHCs.
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We report the need for careful selection of anti-solvents for Sn-based perovskite solar cells fabricated through the commonly used anti-solvent method, compared to their Pb-based counterparts.
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ABSTRACT The core-level photoelectron spectra for Ni(bpy)2(OOCCMe3)2, Ni2(H2O)bpy2(OOCCMe3)4, Nibpy(OOCCMe3)2, Ni(C10H4(CH3)2N(SO2C6H4(CH3), Ni2(2,4-Lut)2(OOCCMe3)4, and (2,4-Lut is 2,4-lutidine) are reported and discussed, and the role... more
ABSTRACT The core-level photoelectron spectra for Ni(bpy)2(OOCCMe3)2, Ni2(H2O)bpy2(OOCCMe3)4, Nibpy(OOCCMe3)2, Ni(C10H4(CH3)2N(SO2C6H4(CH3), Ni2(2,4-Lut)2(OOCCMe3)4, and (2,4-Lut is 2,4-lutidine) are reported and discussed, and the role of ligands in their appearance is determined. X-ray irradiation of some complexes was found to induce removal of some pyridyl rings and oligomerization both at room and liquid nitrogen temperature. The dependence of composition on temperature was used to find correlation between ligand surrounding and the spectra.
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Stainless steel 316L material is commonly used for the production of coronary and peripheral vessel stents. Effective biofunctionalization is a key to improving the performance and safety of the stents after implantation. This paper... more
Stainless steel 316L material is commonly used for the production of coronary and peripheral vessel stents. Effective biofunctionalization is a key to improving the performance and safety of the stents after implantation. This paper reports the method for the immobilization of recombinant antibody fragments (scFv) on stainless steel 316L to facilitate human endothelial progenitor cell (EPC) growth and thus improve cell viability of the implanted stents for cardiovascular applications. The modification of stent surface was conducted in three steps. First the stent surface was coated with titania based coating to increase the density of hydroxyl groups for successful silanization. Then silanization with 3 aminopropyltriethoxysilane (APTS) was performed to provide the surface with amine groups which presence was verified using FTIR, XPS and fluorescence microscopy. The maximum density of amine groups (4.8*10-5 mol/cm(2) ) on the surface was reached after reaction taking place in ethano...
Research Interests: Engineering, Materials Science, Cell Adhesion, Medicine, Stents, and 14 moreBiological Sciences, Cell line, Humans, Surface modification, Coating, Stainless Steel, Surface Properties, Cell Proliferation, Silanization, Materials Testing, Recombinant Proteins, Endothelial Progenitor Cells, silanes, and Single-Chain Antibodies
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Highly selective and stable Ni supported on La2O3–Al2O3 catalyst on the deCO/deCO2 reaction paths for the production of renewable diesel.
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Abstract The study presented herein examines, for the first time in the literature, the role of CaO-MgO as a modifier of γ-Αl2O3 for Ni catalysts for the production of green diesel through the deoxygenation of palm oil. The... more
Abstract The study presented herein examines, for the first time in the literature, the role of CaO-MgO as a modifier of γ-Αl2O3 for Ni catalysts for the production of green diesel through the deoxygenation of palm oil. The characteristics of the catalytic samples were examined by N2 adsorption/desorption, XRD, NH3-TPD, CO2-TPD, H2-TPR, XPS and TEM analysis. The carbon deposited on the catalytic surfaces was characterized by TPO, Raman and TEM/HR-TEM. Experiments were conducted between 300 and 400 °C, at 30 bar. Maximum triglyceride conversion and the yield of the target n–C15–n–C18 paraffins increased with temperature up to 375 °C for both catalysts. Both samples promoted deCO2 and deCO deoxygenation reactions much more extensively than HDO. However, although both catalysts exhibited similar activity at the optimal temperature of 375 °C, the Ni/modAl was more active at lower reaction temperatures, which can be probably understood on the basis of the increased dispersion of Ni on its surface and its lower acidity, which suppressed hydrocracking reactions. Time-on-stream experiments carried out for 20 h showed that the Ni/modAl catalyst was considerably more stable than the Ni/Al, which was attributed to the lower amount and lower crystallinity of the carbon deposits and to the suppression of sintering due to the presence of the CaO-MgO modifiers.
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The Ce–Sm–5Cu catalyst exhibited the highest H2 selectivity from 40% to 75% while producing the highest amount of CO (97–71%) and the lowest amount of CO2 (3–28%).
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Understanding how the brain works requires developing advanced tools that allow measurement of bioelectrical and biochemical signals, including how they propagate between neurons. The introduction of nanomaterials as electrode materials... more
Understanding how the brain works requires developing advanced tools that allow measurement of bioelectrical and biochemical signals, including how they propagate between neurons. The introduction of nanomaterials as electrode materials has improved the impedance and sensitivity of microelectrode arrays (MEAs), allowing high quality recordings of single cells in situ using electrode diameters of ≤20 μm. MEAs also have the potential to measure electroactive biological molecules in situ, such as dopamine, a neurotransmitter in the nervous system. Thus, this work focused on fabricating a functionalised carbon nanotube (CNT)-based MEA to demonstrate its potential for future measurement of small signals generated from excitable cells. To this end, the functionalised CNT MEA has recorded one of the lowest electrochemical interfacial impedances available in the literature, 2.8±0.2 kΩ, for an electrode of its geometric surface area. Electrochemical detection of dopamine revealed again one of the best sensitivity values per area available in the literature, 9.48 μA μM−1 mm−2. Additionally, a limit of detection of 7 nM was recorded for dopamine using the functionalised CNT MEA, with selectivity against common electrochemical interferents such as ascorbic acid. These results indicate improvement beyond currently available MEAs, along with the feasibility of using these devices for multi-site detection of physiologically relevant electroactive biomolecules.
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This paper focuses on the LiFePO4 (LFP) battery, a classical and one of the safest Li-ion battery technologies. To facilitate and make the cathode manufacture more sustainable, two Kynar® binders (Arkema, France) are investigated which... more
This paper focuses on the LiFePO4 (LFP) battery, a classical and one of the safest Li-ion battery technologies. To facilitate and make the cathode manufacture more sustainable, two Kynar® binders (Arkema, France) are investigated which are soluble in solvents with lower boiling points than the usual solvent for the classical PVDF binder. Li-LFP and graphite-Li half cells and graphite-LFP full cells are fabricated and tested in electrochemical impedance spectroscopy, cyclic voltammetry (CV) and galvanostatic charge-discharge cycling. The diffusion coefficients are determined from the CV plots, employing the Rendles-Shevchik equation, for the LFP electrodes with the three investigated binders and the graphite anode, and used as input data in simulations based on the single-particle model. Microstructural and surface composition characterization is performed on the LFP cathodes, pre-cycling and after 25 cycles, revealing the aging effects of SEI formation, loss of active lithium, surfa...
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A greener lubrication solution based on self-assembling methods for steel on silicon nitride hybrid contacts is investigated in this study. Surface initiated atom transfer radical polymerisation (ATRP) is employed to produce oleophilic... more
A greener lubrication solution based on self-assembling methods for steel on silicon nitride hybrid contacts is investigated in this study. Surface initiated atom transfer radical polymerisation (ATRP) is employed to produce oleophilic polymer brushes based on methyl methacrylate (MMA). This paper presents the synthesis and characteristics of poly(MMA) brushes that have been designed to synergize with a PAO lubricant whilst forming a strong covalent bond with the silicon nitride surface. By utilising activators regenerated by electron transfer (ARGET) the amount of catalyst needed is reduced to ppm levels allowing polymerisations to take place in a limited amount of air. The initiators and the polymer brushes formed on silicon nitride surfaces are characterised using XPS, contact angle, gel permeation chromatography and atomic force microscopy. The lubricating effects of the polymer brushes under dry and swollen states are evaluated using lateral force microscopy with a steel colloid.
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Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary... more
Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary difficulty in obtaining n-type conductivity. The ability to form chalcogenide-glass p-n junctions could improve the performance of phase-change memory and thermoelectric devices and allow the direct electronic control of non-linear optical devices. Previously, carrier type reversal has been restricted to the GeCh (Ch = S, Se, Te) family of glasses, with very high Bi or Pb ‘doping’ concentrations (~5-11 at.%), incorporated during high-temperature glass melting. Here, we report the first n-type doping of chalcogenide glasses by ion implantation of Bi into GeTe and GaLaSO amorphous films, demonstrating rectification and photocurrent in a Bi-implanted GaLaSO device. Carrier type reversal is observed at a Bi doping concentration of 0.6 at.%, a 100× lower...
Cs incorporation into perovskite film via a thin Cs2CO3 layer ETL passivation treatment.
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Highly active metal-free mesoporous phosphated silica was synthesized by a two-step process and used as a SO2 hydrogenation catalyst. With the assistance of a microwave, MCM-41 was obtained within a 10 min heating process at 180 °C, then... more
Highly active metal-free mesoporous phosphated silica was synthesized by a two-step process and used as a SO2 hydrogenation catalyst. With the assistance of a microwave, MCM-41 was obtained within a 10 min heating process at 180 °C, then a low ratio of P precursor was incorporated into the mesoporous silica matrix by a phosphorization step, which was accomplished in oleylamine with trioctylphosphine at 350 °C for 2 h. For benchmarking, the SiO2 sample without P precursor insertion and the sample with P precursor insertion into the calcined SiO2 were also prepared. From the microstructural analysis, it was found that the presence of CTAB surfactant was important for the incorporation of active P species, thus forming a highly dispersed, ultrafine (uf) phosphate silica, (Si-P) catalyst. The above approach led to the promising catalytic performance of uf-P@meso-SiO2 in the selective hydrogenation of SO2 to H2S; the latter reaction is very important in sulfur-containing gas purification...