Contact Scanning Research Articles

Functionalisation of the Aluminium Surface by CuCl2 Chemical Etching and Perfluoro Silane Grafting: Enhanced Corrosion Protection and Improved Anti-Icing Behaviour

This study aimed to prepare a facile hierarchical aluminium surface using a two-step process consisting of chemical etching in selected concentrations of CuCl2 solution and surface grafting through immersion in an ethanol solution containing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane. The goal was to achieve superhydrophobic characteristics on the aluminium surface, including enhanced corrosion resistance, efficient self-cleaning ability, and improved anti-icing performance. The surface characterisation of the untreated aluminium and treated in CuCl2 solutions of different concentrations was performed using contact profilometry, optical tensiometry, and scanning electron microscopy coupled with energy dispersive spectroscopy to determine the surface topography, wettability, morphology, and surface composition. The corrosion properties were evaluated using potentiodynamic measurements in simulated acid rain solution and salt-spray test according to ASTM B117-22. In addition, self-cleaning and anti-icing tests were performed on superhydrophobic surfaces prepared under optimal conditions. The results showed that the nano-/micro-structured etched aluminium surface with an optimal 0.5 M concentration of CuCl2 grafted with a perfluoroalkyl silane film achieved superhydrophobic characteristics, with water droplets exhibiting efficient corrosion protection, self-cleaning ability, and improved anti-icing performance with decreased ice nucleation temperature and up to 545% increased freezing delay.

Enhancing 3D printed PET physicochemical properties to prevent bacterial adhesion: Phenolic compound-based approach

Polyethylene terephthalate (PET) has emerged as a versatile and widely used polymeric material in the healthcare sector, particularly for medical device manufacturing, owing to its exceptional properties such as biocompatibility, high uniformity, and mechanical strength. However, the susceptibility of PET to bacterial adhesion remains a critical challenge in medical applications, potentially leading to serious complications for patients. In this study, we assessed, using the contact angle and scanning electron microscopy (SEM) techniques, the effectiveness of various phenolic compounds, including gallic acid (GA), tannic acid (TA), caffeic acid (CA) and epigallocatechin gallate (EGCG), in preventing the adhesion of Staphylococcus aureus and Pseudomonas aeruginosa to 3D printed PET surfaces. The results revealed that PET, initially hydrophobic (θw = 75.7 ± 0.56° and ΔGiwi = −52.17 mJ/m2), became hydrophilic after treatment with TA, GA and CA, enhancing its physicochemical properties. Additionally, GA demonstrated remarkable anti-adhesive efficacy against S.aureus with inhibition percentage of 97.4 %, whereas TA exhibited a high inhibition rate against P.aeruginosa (98.5 %). In contrast, PET remained qualitatively hydrophobic after treatment with EGCG, which showed limited anti-adhesive efficacy with a percentage of coverage by S.aureus and P.aeruginosa of 70.15 and 92.7 %, respectively. These findings contribute to the development of sustainable anti-adhesive surfaces for medical devices.

A Novel Nano-Spherical Tip for Improving Precision in Elastic Modulus Measurements of Polymer Materials via Atomic Force Microscopy.

Micro-nano-scale mechanical properties are vital for engineering and biological materials. The elastic modulus is generally measured by processing the force-indentation curves obtained by atomic force microscopy (AFM). However, the measurement precision is largely affected by tip shape, tip wear, sample morphology, and the contact model. In such research, it has been found that the radius of the sharp tip increases due to wear during contact scanning, affecting elastic modulus calculations. For flat-ended tips, it is difficult to identify the contact condition, leading to inaccurate results. Our research team has invented a nano-spherical tip, obtained by implanting focused helium ions into a silicon microcantilever, causing it to expand into a silicon nanosphere. This nano-spherical tip has the advantages of sub-micro size and a smooth spherical surface. Comparative tests of the elastic modulus measurement were conducted on polytetrafluoroethylene (PTFE) and polypropylene (PP) using these three tips. Overall, the experimental results show that our nano-spherical tip with a consistent tip radius, symmetrical geometric shape, and resistance to wear and contamination can improve precision in elastic modulus measurements of polymer materials.

High-Frequency Dynamic Compensation for Contact Scanning Probe Based on Dual-Parameter Feedback Optimization of Pole Configuration

High-Frequency Dynamic Compensation for Contact Scanning Probe Based on Dual-Parameter Feedback Optimization of Pole Configuration

Development of a Superhydrophobic Protection Mechanism and Coating Materials for Cement Concrete Surfaces.

In order to further enhance the erosion resistance of cement concrete pavement materials, this study constructed an apparent rough hydrophobic structure layer by spraying a micro-nano substrate coating on the surface layer of the cement concrete pavement. This was followed by a secondary spray of a hydroxy-silicone oil-modified epoxy resin and a low surface energy-modified substance paste, which combine to form a superhydrophobic coating. The hydrophobic mechanism of the coating was then analysed. Firstly, the effects of different types and ratios of micro-nano substrates on the apparent morphology and hydrophobic performance of the rough structure layer were explored through contact angle testing and scanning electron microscopy (SEM). Subsequently, Fourier transform infrared spectroscopy and permeation gel chromatography were employed to ascertain the optimal modification ratio, temperature, and reaction mechanism of hydroxy-silicone oil with E51 type epoxy resin. Additionally, the mechanical properties of the modified epoxy resin-low surface energy-modified substance paste were evaluated through tensile tests. Finally, the erosion resistance of the superhydrophobic coating was tested under a range of conditions, including acidic, alkaline, de-icer, UV ageing, freeze-thaw cycles and wet wheel wear. The results demonstrate that relying solely on the rough structure of the concrete surface makes it challenging to achieve superhydrophobic performance. A rough structure layer constructed with diamond micropowder and hydrophobic nano-silica is less prone to cracking and can form more "air chamber" structures on the surface, with better wear resistance and hydrophobic performance. The ring-opening reaction products that occur during the preparation of modified epoxy resin will severely affect its mechanical strength after curing. Controlling the reaction temperature and reactant ratio can effectively push the modification reaction of epoxy resin through dehydration condensation, which produces more grafted polymer. It is noteworthy that the grafted polymer content is positively correlated with the hydrophobicity of the modified epoxy resin. The superhydrophobic coating exhibited enhanced erosion resistance (based on hydrochloric acid), UV ageing resistance, abrasion resistance, and freeze-thaw damage resistance to de-icers by 19.41%, 18.36%, 43.17% and 87.47%, respectively, in comparison to the conventional silane-based surface treatment.

A Comparative Evaluation of Surface Hardness and Nanomechanical Properties of Nickel-Titanium Orthodontic Wires: An In Vitro Study.

The study aimed to evaluate the influence of various surface coatings (epoxy, Teflon, and rhodium) on the surface roughness (SR) and nanomechanical characteristics of nickel-titanium (NiTi) archwires. The study compared these coated archwires to uncoated ones from a single manufacturer, which served as a control. There were 15 rectangular samples of four distinct archwires measuring 0.17 × 0.25. These were ultrasonically treated with an alkaline solution at 60°C for 15 minutes before being rinsed with distilled water to remove precipitates. With an orthodontic soft wire cutter, the straight buccal sections of coated and uncoated archwires were cut into 20 mm lengths. A three-dimensional optical noncontact surface profilometer evaluated the surface. Profilometers use contact scanning white light interferometry. Using the Vision64 software (Bruker Corporation, San Jose, CA), the profilometer's nanolens atomic force microscopy module has a completely automated turret with programmed X, Y, and Z motions. Images were taken in five random locations. Five average measurements matched specimen SR. A nanoindenter with a Berkovich diamond indenter measured nanohardness (NH) and elastic modulus (EM). The experimental results were analyzed using the Statistical Package for the Social Sciences software version 26.0 (SPSS Inc., Chicago, IL). To examine mean differences at 5% significance, analysis of variance and Tukey's post hoc test were applied for SR, NH, and EM. Wires coated with epoxy had the highest SR (1.499 ± 0.082), followed by Teflon (0.811 ± 0.023) and rhodium (0.308 ± 0.024). The SR of the control group was 0.289 ± 0.027. Significant differences in SR were found (p < 0.0001). Except for the comparison between rhodium and the control group (p = 0.684), all intergroup comparisons of SR showed significant differences (p < 0.0001). The rhodium-coated wires exhibited the highest NH (0.185 ± 0.014), and the epoxy group had the lowest (0.147 ± 0.017). Variations in NH were significant between the study groups (p < 0.0001). The epoxy, Teflon, and rhodium groups showed significant differences against the control group (p < 0.0001) in intergroup comparisons for NH. The Teflon group had the highest EM (5.367 ± 0.379), and the epoxy group had the lowest (5.012 ± 0.498). The EM of the control group was 56.946 ± 0.737. Results indicate considerable EM changes between the groups (p < 0.05). Comparisons between experimental and control groups showed significant differences (p < 0.0001). The study's findings indicate that the SR of rhodium-coated archwires is substantially comparable to that of uncoated archwires. However, Teflon-, rhodium-, and epoxy-coated archwires had significantly different NH and EM compared to uncoated ones. Further, uncoated archwires have higher NH and EM.

Green and Abrasion-Resistant Superhydrophobic Coatings Constructed with Tung Oil/Carnauba Wax/Silica for Wood Surface.

As a renewable, environmentally friendly, natural, and organic material, wood has been receiving extensive attention from various industries. However, the hydrophilicity of wood significantly impacts the stability and durability of its products, which can be effectively addressed by constructing superhydrophobic coatings on the surface of wood. In this study, tung oil, carnauba wax, and silica nanoparticles were used to construct superhydrophobic coatings on hydrophilic wood surfaces by a facile two-step dip-coating method. The surface wettability and morphology of the coatings were analyzed by a contact angle meter and scanning electron microscope, respectively. The results suggest that the coating has a micron-nanosized two-tiered structure, and the contact angle of the coating is higher than 150° and the roll-off angle is lower than 10°. Sandpaper abrasion tests and UV diffuse reflectance spectra indicate that the coatings have excellent abrasion resistance and good transparency. In addition, the coated wood shows excellent self-cleaning and water resistance, which have great potential for applications in industry and furniture manufacturing.

Ultrasonic detection method based on flexible capillary water column arrays coupling

Conventional water immersion ultrasonic testing faces limitations due to factors such as environmental conditions, workpiece dimensions, corrosion, and resource wastage. Contact-based coupling methods, which employ coupling media or specific coupling structures, offer a convenient approach to coupling acoustic waves and reduce signal attenuation. However, these methods are time-sensitive and lack adaptability to uneven surfaces, particularly when dealing with workpieces featuring subtle undulations, resulting in significant signal decay. This paper presents an ultrasonic coupling method based on a flexible capillary water column array. By employing a stable and flexible water column array within the micro-channels as the coupling medium, stable contact-based transmission of ultrasonic signals is achieved. The influence of water column array unit dimensions and array structures is explored through theoretical analysis and experimentation, demonstrating lower energy attenuation compared to reductions in water column area. Notably, the tests revealed the method’s adaptability at oblique angles below 20 degrees, which surpasses the performance of submerged detection at similar angles. This research presents an innovative and stable approach for contact-based ultrasonic coupling testing, particularly in scenarios involving dynamic contact scanning between ultrasonic waves and workpieces.

Enhancement of magnetic activation on the backfilling performance of coal gangue-based composite materials

ABSTRACT The large accumulation of coal gangue has resulted in significant environmental contamination and detrimental impacts. Utilizing it as a filler material in coal mining operations may successfully address this issue. It may be used to efficiently alleviate this issue by filling up coal mines. The wettability of magnetized solution on the coal gangue surface and the phase composition, microstructure, and pore structure of hydration products of coal gangue-based composite material (CGCM) at different ages were analyzed by means of contact angle (CA), X-ray diffraction (XRD), thermogravimetry (TG/DTG), mercury intrusion (MIP), and scanning electron microscopy (SEM) in order to control the fluidity and mechanical properties of backfilling materials. Simultaneously, an investigation was conducted on the slump expansion, setting time, and compressive strength of composite filler materials derived from magnetized coal gangue. The findings indicate that the application of a magnetic field reduces the interaction force among the molecules in the mixing water. Consequently, this leads to an improvement in the wettability of the coal gangue particle surface. Thus, the fluidity of the backfilling slurry is improved. The permeability and diffusion characteristics of magnetized water surpass those of regular water, The rate of dissolving and hydration reactions of the cementitious active material in the slurry is increased, resulting in a noticeable reduction in the setting time of the slurry. In the backfilling body, magnetized mixing water can encourage the formation of dicalcium silicate (C2S), tricalcium silicate (C3S), and Ca (OH)2. Higher amounts of C-S-H gel and Aft are produced by the pozzolanic action with SiO2, which enhances the pore structure. Thus, the mechanical qualities of the filler body are enhanced. The study findings provide novel insights into the coal gangue backfill mining and offer an environmentally friendly and efficient approach for the large-scale processing and exploitation of coal gangue.

An Adaptive Control Method and Learning Strategy for Ultrasound-Guided Puncture Robot

The development of a new generation of minimally invasive surgery is mainly reflected in robot-assisted diagnosis and treatment methods and their clinical applications. It is a clinical concern for robot-assisted surgery to use a multi-joint robotic arm performing human ultrasound scanning or ultrasound-guided percutaneous puncture. Among them, the motion control of the robotic arm, and the guiding and contact scanning processes of the ultrasonic (US-) probe determine the diagnosis effect, as well as the accuracy and safety of puncture surgery. To address these challenges, this study developed an intelligent robot-assisted system integrating autonomous US inspection and needle positioning, which has relation to several intelligent algorithms such as adaptive flexible control of the robot arm, autonomous US-scanning, and real-time attitude adjustment of the puncture needle. To improve the cooperativity of the spatial operation of the robot end-effector, we propose an adaptive flexible control algorithm that allows the operator to control the robot arm flexibly with low damping. To achieve the stability and uniformity of contact detection and imaging, we introduced a self-scanning method of US-probe based on reinforcement learning and built a software model of variable stiffness based on MuJoco to verify the constant force and velocity required by the end mechanism. We conducted a fixed trajectory scanning experiment at a scanning speed of 0.06 m/s. The force curve generally converges towards the desired contact force of 10 N, with minor oscillations around this value. For surgical process monitoring, we adopted the puncture needle detection algorithm based on Unet++ to acquire the position and attitude information of the puncture needle in real time. In short, we proposed and verified an adaptive control method and learning strategy by using an UR robotic arm equipped with a US-probe and puncture needle, and we improved the intelligence of the US-guided puncture robot.

Investigation of Gas Diffusion Layer Degradation in Polymer Electrolyte Fuel Cell Via Chemical Oxidation

The gas diffusion layer (GDL) is a key part of the membrane electrolyte assembly and is critical for the transport of fuel, oxygen and water. The GDL is made up of two layers: macroporous substrate (MPS) and microporous layer (MPL) (1). To achieve the hydrophobicity required for water management, the two layers are typically treated with polytetrafluoroethylene (PTFE) (2). In many long-term experiments, it has been observed that GDL degradation, such as carbon corrosion and PTFE loss, leads to a deterioration of water management, conductivity and mass transport (3).To solve this durability problem, a thorough and in-depth understanding of the GDL degradation mechanism is required. In this study, GDLs are subjected to an accelerated stress test to investigate degradation by chemical oxidation. GDLs are soaked in Fenton's reagent for 24 hours. The hydrophobic properties of pristine and soaked GDLs are compared based on contact angle measurements, thermogravimetry and scanning electron microscopy. In addition, the chemical composition of the solutions before and after the immersion test is analyzed using a total organic carbon analyzer and an ion chromatograph. The results show that the hydrophobicity of GDL exposed to Fenton reagent is decreased by 5 and 4 degrees for the MPL and the MPS respectively. Fig 1. depicts a decrease in surface contact angle, which is associated with surface oxidation and PTFE deterioration.AcknowledgementThis research work is performed under the project AlpeDHues (AlpeDHues / FFG 889328) which is supported by the Austrian Research Promotion Agency (FFG).References C. Csoklich, R. Steim, F. Marone, T. Schmidt and F. Büchi, ACS Applied Materials & Interfaces, 13, 9908–9918 (2021).A. Ozden, S. Shahgaldi, X. Li and F. Hamdullahpur, Progress in Energy and Combustion Science, 74, 50–102 (2019).Y. Yang, X. Zhou, B. Li and C. Zhang, Applied Energy, 303, 117688 (2021). Figure 1

Effectiveness of Different Application Modalities on the Bond Performance of Four Polymeric Adhesive Systems to Dentin.

One of the major goals of adhesive dentistry is to improve the interaction of the already-existing adhesives with different substrates by using different application techniques. Thus, the objective of the present in vitro study was to assess the bond performance of four adhesive systems, Prime&Bond Universal (PBU), Clearfil SE Bond (CSE), OptiBond Universal (OBU), and OptiBond FL (OBFL), to dentin using various application modes: passive application (PA), active application (AA), Compo-Vibes modified application (CVM), and Compo-Vibes application (CV). Eighty extracted human molars were allocated into four groups based on the application modalities tested. The micro-tensile bond strength as well as fracture mode were tested in accordance with ISO/TS 11.405 after 24 h and 6 months of aging. Adhesive contact angle (CA) and scanning electron microscope analysis were also performed (n = 3). Statistical tests were performed with α = 0.05. After 24 h, a significant difference with a higher bond strength value was found for PBU in the AA modality and for CSE in the CVM modality (p < 0.05). However, no significant difference was shown between the techniques used among the other adhesives (OBFL and OBU). Moreover, at 24 h, only the PA demonstrated significant differences between the tested materials (p < 0.05). After 6 months, CSE, PBU, and OBU demonstrated significant differences between the techniques (p < 0.05), with a higher bond strength for CSE in AA and CVM modalities, for PBU in AA modality, and for OBU in AA and PA modalities. No significant differences were found between the techniques used among the OBFL (p > 0.05). In addition, only the CVM technique demonstrated significant differences between the tested materials after 6 months. CV and CVM showed a decreased value after aging for CSE and PBU, respectively. However, all the modalities decreased for OBU and OBFL after aging. All the adhesives showed marked resin infiltration into dentinal tubules in AA among all the modalities tested. Both universal adhesive systems (OBU and PBU) demonstrated statistically lower CA when compared to the other systems (CSE and OBFL) (p < 0.05) when applied in the PA mode. Concerning the AA mode, only CSE and OBFL were tested. The AA demonstrated lower CA values compared to the same adhesives in PA (p < 0.05). It could be concluded that the bond strength could be influenced by both materials and application techniques. It seems that the AA technique could be recommended as a gold standard for the application of an adhesive system to dentin. Plus, the CV and CVM modalities after 6 months of aging were considered stable for PBU and CSE, respectively. Consequently, the performance of these adhesive systems might vary when applied to other modalities. Future studies are needed to test this hypothesis.

Carboxymethyl chitosan-TK resistant starch complex ameliorates type 2 diabetes by regulating the gut microbiota

Carboxymethyl chitosan and resistant starch exhibit good performance in diabetes regulation. We prepared carboxymethyl chitosan - resistant starch complex. Test the properties of composite resistant starch by using X-ray diffraction, water contact angle, infrared spectroscopy, and scanning electron microscopy, interactions with intestinal microbiota and mouse experiments were also conducted. The results indicated that the composite resistant starch had a good effect on promoting the proliferation of probiotics on Bifidobacterium and a significant inhibitory effect on Escherichia coli than resistant starch (P < 0.05). After administration, the water intake and weight of diabetic mice were significantly reduced. The blood glucose of diabetic mice was also reduced, and oral glucose tolerance showed that the glucose degradation rates of composite resistant starch were significantly improved compared to model mice. Cholesterol, triglycerides, high-density lipoprotein and low-density lipoprotein were significantly lower than those in the diabetes group (P < 0.05). The diversity of the gut microbiota was also proven.

Effect of Er: YAG laser and plasma treatment on the bond strength of Y-TZP

ObjectivesThis study aimed to evaluate the effects of Er:YAG laser and plasma treatment on the bond strength between Y-TZP and resin cement. Materials and methodsSixty yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) specimens were fabricated and randomly assigned to six groups (n = 10): control group (group A); Sandblasting treatment (group B); Er:YAG laser group (group C); Ar plasma group (group D); Sandblasting + Ar plasma group (group E); and Er:YAG laser + Ar plasma group (group F). The surface of each zirconia specimen was tested using a contact angle meter, profilometer, and scanning electron microscope, and the shear bonding strength (SBS) was calculated. Statistical analysis was performed with One-way analysis of variance (ANOVA) combined with a least significant difference (LSD) test. ResultsThe surface morphology showed no difference between group A and group D, with smooth surfaces and shallow scratches after polishing. The surface roughness value of group C was 2.58 ± 0.14μm and was not significantly different from that of group F (P > 0.05), was higher than that of group A (P < 0.05). The SBS of group B was not significantly different from that of group D (P > 0.05). The hydrophilicity, carbon and oxygen contents, and SBS of group E were similar to those of group F (P > 0.05) and significantly higher than those of groups A, B, C, and D (P < 0.05). SignificanceThe Er:YAG laser and Ar plasma treatment can improve the bonding strength between zirconia and resin cement, and mechanical treatment followed by Ar plasma surface modification is more effective.

Effect of organosilicon modified epoxy resin on slurry viscosity and mechanical properties of polyurethane grouting materials

Polyurethane (PU) grouting reinforcement materials are widely used in the construction and maintenance of civil engineering works such as coal mine, high-speed railways, subways and tunnels. The initial viscosity, allowable operation time and the mechanical strength of the grouting material are important factors affecting its application and how to strike a balance between these three factors is a key challenge in this field. In this study, a new strategy was proposed to overcome these problems. The use of alkoxy silane groups attached to the main chain of epoxy resin can reduce the entanglement between molecular chains and thus increase the flexibility of polyurethane molecular chain. A series of organosilicon modified epoxy (ME) resins were synthesized by modifying bisphenol A epoxy resin E51 with silane coupling agent KH550. The viscosity, mechanical properties and thermal stability organosilicon epoxy modified polyurethane (MEPU) were studied by adjusting the amount of ME. The apparent viscosity and shear strain viscosity of organosilicon epoxy modified polyurethane (MEPU) were investigated by means of a rotational viscometer and a rotational rheometer. The effect of ME on the mechanical properties of MEPU was systematically studied through the mechanical properties test (compression test, tensile test and impact test). The surface properties and microstructure of MEPU were investigated by water contact angle testing and scanning electron microscopy. The resulting MEPU exhibits low slurry viscosity and high compressive strength. Slurry viscosity tends to decrease as the proportion of ME increases. Compared to the unmodified polyurethane grouting slurry, MEPU-15 shows a significant reduction in slurry viscosity and maximum curing temperature for 48.7% and 8 ℃ respectively, and the consolidation fracture toughness increases 28.7%. At the same time, the addition of ME changes the polyurethane grouting material from hydrophilic to hydrophobic. In this work, polyurethane grouting materials with low slurry viscosity, high mechanical strength and low exothermic reaction have been successfully synthesized. It is possible for polyurethane grouting material to be applied more widely.

Temporary Anti-Corrosive Double Layer on Zinc Substrate Based on Chitosan Hydrogel and Epoxy Resin.

In practice, metal structures are frequently transported or stored before being used. Even in such circumstances, the corrosion process caused by environmental factors (moisture, salty air, etc.) can occur quite easily. To avoid this, metal surfaces can be protected with temporary coatings. The objective of this research was to develop coatings that exhibit effective protective characteristics while also allowing for easy removal, if required. Novel, chitosan/epoxy double layers were prepared on zinc by dip-coating to obtain temporary tailor-made and peelable-on-demand, anti-corrosive coatings. Chitosan hydrogel fulfills the role of a primer that acts as an intermediary between the zinc substrate and the epoxy film to obtain better adhesion and specialization. The resulting coatings were characterized using electrochemical impedance spectroscopy, contact angle measurements, Raman spectroscopy, and scanning electron microscopy. The impedance of the bare zinc was increased by three orders of magnitude when the protective coatings were applied, proving efficient anti-corrosive protection. The chitosan sublayer improved the adhesion of the protective epoxy coating. The structural integrity and absolute impedance of the protective layers were conserved in both basic and neutral environments. However, after fulfilling its lifespan, the chitosan/epoxy double-layered coating could be removed after treatment with a mild acid without damaging the substrate. This was because of the hydrophilic properties of the epoxy layer, as well as the tendency of chitosan to swell in acidic conditions.

Corrosion inhibition of mild steel in hydrochloric acid solution by the expired Ampicillin drug

This study examines the utilization of the expired drug, namely ampicillin, as a mild steel corrosion inhibitor in an acidic environment. The inhibitor was evaluated using weight loss and electrochemical measurement accompanied with surface analytical techniques. The drug showed a potential inhibitory efficiency of > 95% at 55 °C. The inclusion of the inhibitor increased the charge transfer resistance at the steel-solution interface, according to impedance analyses. According to potentiodynamic polarisation measurements, expired ampicillin drug significantly decreased the corrosion current density and worked as a mixed-type corrosion inhibitor. The Langmuir adsorption isotherm was followed by the adsorption of ampicillin drug on the steel substrate, exhibiting an association of physical and chemical adsorption mechanisms. The surface study performed using contact angle and scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) measurements supported the inhibitor adsorption on the steel substrate.

Physicochemical characterization of reusable facemasks and theoretical adhesion by a challenged bacterium.

Adhesion of microorganisms on facemask surfaces is a major problem that produces contamination of the mask wearer either by inhalation or by direct contact. Generally, physicochemical properties of the material and the microorganism are responsible for this adhesion and are also reported to influence the filtration efficiency of facemasks. However, theses surface proprieties and their effect on particles attachment on facemask materials remain poorly documented. The purpose of this study was to investigate the physicochemical properties of seven facemasks and evaluate the influence of these characteristics on the adhesion of Sataphylococcus aureus. Physicochemical properties is done by contact angle method and scanning electron microscopy while theoretical adhesion of S. aureus is done according to XDLVO approach. The obtained results showed that all masks have a hydrophobic character. The electron donor and electron acceptor parameters change depending on each mask. Chemical analysis demonstrates the presence of two chemical elements (carbon and oxygen). Predictive adhesion demonstrate that S. aureus has an attractive behavior towards the masks used but the potential of adhesion is not the same. Such information is valuable to understand attachment of biological particles and to contribute in the inhibition of this attachment.

Effect of oil carboxylate hydrophobicity on calcite wettability and its reversal by cationic surfactants: An experimental and molecular dynamics simulation investigation

The oil-wet state of carbonate reservoirs presents a serious challenge for oil recovery. While cationic surfactants are able to reverse the wettability, their efficiency depends on the oil composition, particularly on the carboxylates as the main surface-active compounds. In this study, calcite surface was aged by two distinct carboxylates: a shorter, less hydrophobic octanoate and a more hydrophobic stearate. The surface wettability and its reversal by a quaternary ammonium cationic surfactant were studied both experimentally by contact angle measurements and Scanning Electron Microscopy (SEM) imaging, and by molecular dynamics (MD) simulations. Both simulations and experiments show that aging with the more hydrophobic stearates yields more strongly oil-wet surfaces, whose wettability is more difficult to reverse by the cationic surfactant, than aging with octanoates. While the surfactant ultimately reverses the wettability in both cases, significantly higher surfactant concentration is required for the stearate-aged calcite. The difference in the wettability can be rationalized by the greater hydrophobicity of the stearate, which strengthens both the surface adsorption and attraction of the non-polar oil phase.

Germination enhancement of mustard (Brassica nigra) seeds using dielectric barrier discharge (DBD)

There have been continual attempts to identify alternatives to increase the agricultural output to improve the living standards of farmers, meet the current demand, and promote sustainability in commercial agriculture. Within this paradigm, low-temperature plasma (LTP) treatments have piqued the attention of investigators and are presently being extensively researched in the agriculture sector. A preliminary study was conducted on mustard seeds (Brassica nigra) to examine the potential of LTP in agriculture to enhance germination and productivity. The seeds were subjected to LTP treatment for 1 to 4 min in an argon environment (11.7 kV, 50 Hz, and Q = 3 L/min) at atmospheric pressure. The germination and growth parameters of the untreated and treated seeds were calculated on the 16th day of the seeds’ germination and compared. All germination and growth-related parameters were found to be improved in LTP-exposed seeds up to 3 min. However, the germination and growth-related parameters deteriorated in 4-min LTP-treated seeds compared to those of control and other treatment time seeds. The water contact angle and scanning electron micrograph images clearly indicated that there is a significant change in the seed coat after being exposed to LTP for a specific time period. The treated seed’s texture was significantly rougher than that of the control, which is directly related to the hydrophilicity of seeds. The findings of this study suggest that using seeds exposed to LTP for a suitable time results in a considerable increase in the germination percentage of sown seeds while also hastening seedling growth and development.