Combined atomic force microscopy–scanning electrochemical microscopy (AFM–SECM) is for the first time used to generate single corrosion pits on passivating iron surfaces in the micrometer range. The ...AFM–SECM probe locally generates nitric acid during the oxidation of nitrite ions with the release of protons at selected sites on the surface of the otherwise passive metal. High confinement of passive film breakdown is achieved from the combination of a small probe size and the inhibiting properties of non-reacted nitrite ions on the surrounding passivated surface. Simultaneous visualization of pit nucleation and propagation can be obtained in the same solution without changing the probe by AFM.
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•The operation of combined AFM–SECM for the nucleation of corrosion pits•Single pit nucleation initiated from the combined effect of acidity and chloride ions•Dual characteristics of nitrite as corrosion inhibitor and precursor for corrosive attack•Real time visualization of pit topography during pit nucleation
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The use of SEM-DIC, AFM, ECCI, and HR-EBSD to characterize slip-system activity was assessed on the same material volume of Ti-7Al. This study presents a robust comparison of the various methods for ...the first time, including an assessment of their advantages and disadvantages, and how they can be used effectively in a complementary fashion. The analysis of the different approaches was carried out in a blind, round-robin manner at three different universities. A Ti-7Al specimen was deformed in uniaxial tension to approximately 3% axial strain, and the active slip systems were independently identified using (i) trace analysis; (ii) in-SEM digital image correlation, (iii) observations of residual dislocations from ECCI, and (iv) long-range rotation gradients through HR-EBSD, with consistent trace identification in all cases. Displacement data from AFM was used to augment SEM-DIC displacement data by providing complementary out-of-plane displacement information. Furthermore, short-range dislocation gradients (measured by DIC) provided insight into the residual geometrically necessary dislocation (GND) content, and was consistent with the GND content extracted from EBSD data and ECCI images, confirming the presence of residual GNDs on the dominant slip systems resulting in visible slip bands. Furthermore, these approaches can be used in tandem to provide multi-modal information on slip band identification, strain and orientation gradients, out-of-plane displacements, and the presence of GNDs and SSDs, all of which can be used to inform and validate the development of dislocation-based crystal plasticity and strain gradient models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Understanding the structural evolution of SiC implanted with fission product surrogates in the presence of helium (He) is of importance for its application in both fission and fusion rectors. In this ...study, polycrystalline SiC wafers were sequentially co-implanted with 360 keV Sr and 21.5 keV He ions to a fluence of 2 × 1016 cm-2 and 1 × 1017 cm-2 at room temperature, respectively. The samples were then isochronally annealed in temperatures ranging from 1000 to 1300 °C for 5 h. Transmission electron microscopy (TEM) showed the formation of He-nanobubbles corresponding to helium's projected range. While scanning electron microscopy (SEM) revealed the formation of cornflower-like structures on the surface of the Sr + He–SiC samples after annealing. These were confirmed to be holes by atomic force microscopy (AFM), as a result of exfoliation and pressurized out-diffusion of helium gas from the samples. The Sr + He–SiC samples were completely amorphized characterized by the formation of the homonuclear bonds in Raman spectroscopy. The recovery process after annealing in the Sr + He–SiC samples resulted in the formation of graphite due to antisite defects driven by the growth of holes above the threshold chemical disorder. Time-of-flight heavy ions elastic recoil detection analysis (Tof-ERDA) showed that almost all helium out-diffused after annealing at 1000 °C and Sr atoms trapped in He cavities.
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•After implantation, an amorphous layer is formed.•Recrystallization occurred after annealing.•After annealing at high temperatures, He exo-diffused through the free surface.•He-induced defects (cavities) represents the center of trapping of Sr atoms.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
MXene has been widely used in energy storage, photocatalysis and lubrication area due to its good mechanical, electrical, and chemical properties. However, its friction and adhesion properties have ...not yet been fully grasped. In this study, for the first time, atomic force microscopy (AFM) Nanoman technology was used to compare the nano friction and adhesion of Ti3C2 and Nb2C MXene. The results indicated that the friction and adhesion of Nb2C were less than Ti3C2 under the same conditions, which is related to the difference in surface dipole moment density. In addition, adhesion and friction of both two MXenes decrease with the temperature increase. This study provides a broader application prospect for these new materials.
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•The friction and adhesion of Nb2C were less than Ti3C2 under the same conditions.•Adhesion and friction force of Ti3C2 and Nb2C MXenes decrease with the temperature increase.•The differences in friction and adhesion between Ti3C2 and Nb2C MXene are related to its surface dipole moment density.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The corrosion inhibition performance of three novel imidazole derivatives namely 2-(4-methoxyphenyl)-4,5-diphenyl-imidazole (M-1), 4,5-diphenyl-2-(p-tolyl)-imidazole (M-2) and ...2-(4-nitrophenyl)-4,5-diphenyl-imidazole (M-3) for J55 steel in CO2 saturated brine solution was studied by weight loss method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM), contact angle, scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and quantum chemical calculation. M-1 exhibited the best inhibition efficiency of 93% at 400 mg/L concentration. The adsorption of the imidazole derivatives obeyed the Langmuir adsorption isotherm. Contact angle measurement reveals the hydrophobic nature of J55 steel in presence of inhibitors. Quantum chemical calculation well supports the experimental results.
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•J55 steel protection in 3.5% NaCl with CO2 in presence of imidazole derivatives.•Tafel curves reveal that the inhibitors are mixed type but anodically dominant.•The inhibitors obey the Langmuir isotherm and Kads and ΔG°ads are also discussed.•Examination of surface morphology by SECM and SEM.•Correlation between experimental and Quantum chemical results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•Synthesis of Bismuth doping Nickel ferrite (NBF) was done by a simple and cost-effective sol–gel auto-combustion method.•The crystalline size obtained from the XRD pattern, ...calculated by the Debye Scherer formula as increasing from 34 to 11 nm by varying concentrations of Bi3+ with lattice parameters ranging from 8.3391 to 8.3147 A0.•The dielectric constant and tangent loss decrease with frequency value and increasing conductivity, measured as a function of frequency using L.C.R.-Q meter in the frequency range 100 Hz to 5 MHz with an accuracy of 0.001 Hz.•The noticeable decrease in the crystallite size in nickel ferrite was observed by increasing Bismuth doping with improving band gap and magnetization saturation for energy storage devices.
The Bi3+ ions doped spinel Nickel ferrite NiBixFe2-xO4 (NBF) where, x = 0, 0.025, 0.050, 0.075, 0.1, 0.125, 0.150 was synthesized by sol–gel auto combustion method. The properties of prepared NBF were studied by using X-ray diffraction, UV–Vis spectroscope, Vibrating Sample Magnetometer, Fourier Transform Infrared Spectroscopy, Atomic Force Microscope, Scanning electron microscope, etc. X-ray diffraction showed that increasing the concentration of Bi3+ ions led to a decrease in crystallite size from 34 to 11 nm and lattice parameters ranging from 8.339 to 8.315 Å, confirming the formation of single-phase cubic spinel structure NBF also the crystallite size calculated by using Williamson Hall plot, is 15 to 36 nm. The energy band gap studied using UV–Vis spectroscopy decreases from 1.510 to 1.418 eV. The dielectrics and AC conductivity of NBF were studied by LCR-Q meter by varying frequency.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Graphene structural defects, namely edges, step-edges, and wrinkles, are susceptible to severe mechanical deformation and stresses under tribo-mechanical operations. Applied forces may cause ...deformation by folding, buckling, bending, and tearing of these defective sites of graphene, which lead to a remarkable decline in normal and friction load bearing capacity. In this work, we experimentally quantified the maximum sustainable normal and friction forces, corresponding to the damage thresholds of the different investigated defects as well as their pull-out (adhesion) forces. Horizontal wrinkles (with respect to the basal plane, i.e., folded) sustained the highest normal load, up to 317 nN, during sliding, whereas for vertical (i.e., standing) wrinkles, step-edges, and edges, the load bearing capacities are up to 113, 74, and 63 nN, respectively. The related deformation mechanisms were also experimentally investigated by varying the normal load up to the initiation of the damage from the defects and extended with the numerical results from molecular dynamics and finite element method simulations.
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IJS, KILJ, NUK, PNG, UL, UM
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•Synthetic Peptides are effective against Penicillium digitatum.•Synthetic peptides induced severe morphological damage in P. digitatum.•Synthetic Peptides induced membrane pore ...formation and ROS overproduction.•Synthetic peptides are highly effective compared to commercial food preservative.•Synthetic peptides have the biotechnological potential to prevent fungal food spoilage.
Fungal contamination is among the main reasons for food spoilage, affecting food safety and the economy. Among fungi, Penicillium digitatum is a major agent of this problem. Here, the in vitro activity of eight synthetic antimicrobial peptides was assessed against P. digitatum, and their action mechanisms were evaluated. All peptides were able to inhibit fungal growth. Furthermore, atomic force and fluorescence microscopies revealed that all peptides targeted the fungal membrane leading to pore formation, loss of internal content, and death. The induction of high levels of reactive oxygen species (ROS) was also a mechanism employed by some peptides. Interestingly, only three peptides (PepGAT, PepKAA, and Mo-CBP3-PepI) effectively control P. digitatum colonization in orange fruits, at a concentration (50 µg mL−1) 20-fold lower than the commercial food preservative (sodium propionate). Altogether, PepGAT, PepKAA, and Mo-CBP3-PepI showed high biotechnological potential as new food preservatives to control food infection by P. digitatum.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The rejuvenating effect for aged binders was thoroughly evaluated at both macro- and micro-scales.•Results suggest that changes in chemical compositions contributed to mechanical properties ...variations.•Characterization of the rejuvenating effect benefits the effort for better recycling bituminous materials.
With the increasing environmental awareness and rising costs of virgin binders, reclaimed asphalt pavement (RAP) has been used as an alternative for energy and cost saving in asphalt pavements. However, RAP binders have been aged to different extents during pavements’ service life and adding rejuvenating agents provides a practical means for restoring the mechanical properties of the aged binders reducing the needed additional virgin binder. In many studies, the rejuvenating effect has been evaluated in terms of the improvement of rejuvenated binders’ rheological properties whereas the fundamental rejuvenation mechanism remains unclear. In this research, two different asphalt binders from the Materials Reference Library of the Strategic Highway Research Program (SHRP) were aged, and rejuvenated by complete blending with two commonly used rejuvenators. The rheological properties of the virgin, aged, and rejuvenated binders were tested using the dynamic shear rheometer and the bending beam rheometer. Furthermore, in order to better understand the rejuvenating effect, surface microscopic properties and chemical composition of the binders were measured using atomic force microscopy (AFM) and SARA (Saturates, Aromatics, Resins, Asphaltenes) fractionation, respectively. Results indicated that the bulk mechanical properties (complex modulus and viscosity) of the rejuvenated binders were in between those of the virgin and aged binders. Aging and rejuvenation led to morphological changes as compared to their virgin binders; however, the rejuvenated binders did not always reproduce the microstructures of the virgin binders. Microscopic measurements on adhesion and dissipation of virgin, aged, and rejuvenated samples were qualitatively consistent with the bulk rheological results. SARA separation results suggested that changes in chemical fractions were responsible for the stiffening effect of aging and the improvement of mechanical properties with the addition of the rejuvenators. Such a systematic approach of characterizing the rejuvenating mechanism will benefit the effort of producing more sustainable RAP-containing asphalt pavements.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Ceramic membranes are among the most promising technologies for membrane applications, owing to their excellent resistance to mechanical, chemical, and thermal stresses. However, membrane fouling is ...still an issue that hampers the applications at large scales. Air Nano Bubbles (NBs), due to high mass transfer efficiency, could potentially prevent fouling of ceramic membrane filtration processes. In this study, bench and pilot scale ceramic membrane filtration was performed with air NBs to resist fouling. To simulate fouling, humic acid, as an organic foulant, was applied to the membrane flat sheet surface. Complete membrane clogging was achieved in less than 6 h. Membrane defouling (cleaning) was performed by directly feeding of air NBs to the membrane cells. The surface of the ceramic membrane was superbly cleaned by air NBs, as revealed by atomic force microscope (AFM) images before and after the treatment. The permeate flux recovered to its initial level (e.g., 26.7 × 10−9 m3/m2/s at applied pressure of 275.8 kPa), which indicated that NBs successfully unclogged the pores of the membrane. The integrated ceramic membrane and air NBs system holds potential as an innovative sustainable technology.
•The membrane fouled surface was cleaned by feeding air NBs into the membrane holder.•It was predicted that OH• radicals make a bond with organic foulants like humic acids and break down the organic matter.•NBs dramatically cleaned the membrane with minimum observed adverse effects.•The Cubic method showed the most accurate prediction of the permeate flux at any of the applied pressures and times.•The economic benefit of air NBs application is minimizing the usage of chemicals.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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