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16 pages, 1249 KiB

Open AccessArticle

Impact of Electromagnetic Field on the Physicochemical Properties, Permeability, and Accumulation of Salicylic Acid

by Karolina Zyburtowicz-Ćwiartka, Anna Nowak, Anna Muzykiewicz-Szymańska, Łukasz Kucharski, Maciej Konopacki, Rafał Rakoczy and Paula Ossowicz-Rupniewska

Appl. Sci. 2025, 15(13), 7606; https://doi.org/10.3390/app15137606 - 7 Jul 2025

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Abstract

Transdermal drug delivery offers a non-invasive route for the systemic and localized administration of therapeutics; however, the skin’s barrier function limits its efficiency. This study investigates the application of various electromagnetic field (EMF) configurations to enhance the transdermal delivery of salicylic acid, a [...] Read more.

Transdermal drug delivery offers a non-invasive route for the systemic and localized administration of therapeutics; however, the skin’s barrier function limits its efficiency. This study investigates the application of various electromagnetic field (EMF) configurations to enhance the transdermal delivery of salicylic acid, a model compound with moderate lipophilicity and ionizability. Samples were exposed to pulsed, oscillating, static, and rotating magnetic fields, and their effects on physicochemical properties, thermal stability, skin permeation, and accumulation were evaluated. Structural analyses (FTIR, XRD) and thermal assessments (TGA, DSC) confirmed that EMF exposure did not alter the chemical structure or stability of salicylic acid. In vitro transdermal studies using porcine skin and Franz diffusion cells revealed that pulsed magnetic fields—especially with a 5 s on/5 s off cycle—and rotating magnetic fields at 30–50 Hz significantly enhanced drug permeation compared to controls. In contrast, static fields of negative polarity increased skin retention, suggesting their potential for controlled, localized delivery. These findings demonstrate that EMFs can be used as tunable, non-destructive tools to modulate drug transport across the skin and support their integration into transdermal delivery systems aimed at optimizing therapeutic profiles. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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15 pages, 10114 KiB

Open AccessArticle

Effect of Grain Size and Incidence Angle on Erosive Wear of Polyurea Coating

by Justyna Sokolska and Piotr Sokolski

Appl. Sci. 2025, 15(13), 7568; https://doi.org/10.3390/app15137568 - 5 Jul 2025

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Abstract

This study investigated the erosive wear of a polyurea coating with a hardness of 95 ShA and a thickness of 3 mm applied to a 3 mm thick plate made of S235 steel. The process of erosive wear was carried out using a [...] Read more.

This study investigated the erosive wear of a polyurea coating with a hardness of 95 ShA and a thickness of 3 mm applied to a 3 mm thick plate made of S235 steel. The process of erosive wear was carried out using a stream of compressed air containing abrasive grains of aluminum oxide (Al₂O₃). The erosive wear was studied using different incidence angles (45°, 60° and 90°) and erosive grain sizes. Thus, the effects of the incidence angle and erosive grain size on the erosive wear of the polyurea coating were analyzed. Erosive wear was determined as linear wear: the depth of the wear trace was measured using an optical profilometer. This study showed a non-linear correlation between erosive wear, incidence angle and erosive particle size. In addition, a qualitative study of the surface of the coating after a wear test was carried out using a scanning electron microscope, which made it possible to describe the mechanisms of erosive wear of the polyurea coating. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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19 pages, 3609 KiB

Open AccessArticle

The Influence of a Biopolymer Coating on Selected Surface Properties of Soilless Substrates Made from Coconut Fibre

by Maciej Balawejder, Natalia Matłok, Małgorzata Szostek and Maciej Kuboń

Appl. Sci. 2025, 15(13), 7039; https://doi.org/10.3390/app15137039 - 23 Jun 2025

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Abstract

Horticultural substrates based on coconut fibre are among the most commonly used growing media, but with limited durability. This study presents methods for modifying coconut fibre through surface coating with biopolymers, where polymerisation was initiated in the applied solution. Additionally, the suitability of [...] Read more.

Horticultural substrates based on coconut fibre are among the most commonly used growing media, but with limited durability. This study presents methods for modifying coconut fibre through surface coating with biopolymers, where polymerisation was initiated in the applied solution. Additionally, the suitability of adding pelletised biochar was analysed. A biomonomer derived from wood processing was used both for fibre surface modification and for binding biochar into pellets. Surface modification through biopolymer coating resulted in changes to selected physicochemical properties. It was found that the coating significantly altered the porosity of the substrate. Depending on the type of coconut fibre, the differences in porosity compared to the unmodified substrate ranged from 12 to 24%. This directly influenced bulk density, which is a crucial parameter in the preparation of substrates for plant growth. The surface properties of the modified substrates also affected sorption and retention capacities. From the perspective of plant production, the supply of bioavailable forms of potassium and phosphorus is essential. Coating and the addition of pelletised biochar, regardless of the type of fibre used, significantly increased the release of PO₄³⁻ and K⁺ compared to unmodified substrates. The physiological parameters in plants confirmed the suitability of the modified substrates for plant production. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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15 pages, 3599 KiB

Open AccessArticle

Electrochemically Engineered Mesoporous Sn-Oxide Rods for Anode Materials in Lithium-Ion Batteries

by Woo-Jin Lee, Yu-Jeong Min and Heon-Cheol Shin

Appl. Sci. 2025, 15(11), 6026; https://doi.org/10.3390/app15116026 - 27 May 2025

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Abstract

Sn-based anodes for lithium-ion batteries (LIBs) offer high capacity and low cost; however, significant volume changes during lithiation/delithiation cause mechanical degradation, limiting their practical applications. Microstructural control is a key approach to mitigating these volume changes. This study reports the fabrication of core [...] Read more.

Sn-based anodes for lithium-ion batteries (LIBs) offer high capacity and low cost; however, significant volume changes during lithiation/delithiation cause mechanical degradation, limiting their practical applications. Microstructural control is a key approach to mitigating these volume changes. This study reports the fabrication of core (Sn rod)-shell (mesoporous Sn-oxide layer) structures through electrodeposition followed by anodization, and their applications to anode active materials for LIBs. First, micro-Sn rods with controlled lengths and diameters were fabricated under various electrodeposition conditions. The electrodeposited Sn exhibited a dendritic structure with short secondary rods branching from a long primary rod. While the primary Sn rod diameters remained constant, the secondary rod diameters varied depending on electrodeposition parameters. Notably, rod coarsening due to secondary rod agglomeration occurred at higher currents and longer deposition durations during galvanostatic electrodeposition. In contrast, potentiostatic electrodeposition prevented agglomeration and increased the quantity of Sn rods with voltage. Subsequently, the core-shell structures were fabricated by anodizing Sn rods, forming mesoporous Sn-oxide layers with different pore sizes and pore wall thicknesses. Electrochemical characterization revealed that the core-shell anode performance for LIBs varied with the Sn-oxide shell’s microstructure. These findings provide insights into optimal core-shell structures to improve anode performance for LIBs. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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16 pages, 7531 KiB

Open AccessArticle

Mg-Doped Carbonated Hydroxyapatite and Tricalcium Phosphate Anodized Coatings on Titanium Implant Alloys

by Amisha Parekh, Maggie Moore, Amol V. Janorkar and Michael D. Roach

Appl. Sci. 2024, 14(24), 11831; https://doi.org/10.3390/app142411831 - 18 Dec 2024

Cited by 3 | Viewed by 1204

Abstract

The rising demand for dental and orthopedic implants and their frequent aseptic loosening failure mode necessitate the drive to continue modifying implant surfaces to improve osseointegration outcomes. Plasma-sprayed hydroxyapatite coatings are widely used but are prone to delamination. This study involves a single-step [...] Read more.

The rising demand for dental and orthopedic implants and their frequent aseptic loosening failure mode necessitate the drive to continue modifying implant surfaces to improve osseointegration outcomes. Plasma-sprayed hydroxyapatite coatings are widely used but are prone to delamination. This study involves a single-step anodization process utilizing a novel electrolyte to produce Mg-doped carbonated hydroxyapatite and tricalcium phosphate-containing coatings on four titanium alloy surfaces. XRD confirmed hydroxyapatite and tricalcium phosphate formation, with FTIR examination revealing carbonate substitutions indicative of bone-like apatite formation in each oxide. SEM analyses revealed micro- and nano-scaled surface features on each oxide. SEM and EDS analyses of the oxide coating cross-sections showed each group to be bi-layered with an inner titanium dioxide-rich layer and an outer hydroxyapatite/tricalcium phosphate-rich layer. The oxide layer adhesion quality was shown to be good on CPTi, TAV, and TiMo α + β implant alloy surfaces. Unfortunately, the anodization process also resulted in an undesirable and embrittling omega phase at the substrate–oxide interface due to the migration of molybdenum into the inner oxide. Nonetheless, the anodized coatings on the CPTi and TAV alloy substrates, which are the most widely used titanium alloys for implant applications, show much potential for improving future patient outcomes. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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14 pages, 6535 KiB

Open AccessArticle

Electrochemical Corrosion Resistance of Al₂O₃–YSZ Coatings on Steel Substrates

by Ramona Cimpoeșu, Marian Luțcanu, Alin Marian Cazac, Ionuț Adomniței, Costică Bejinariu, Liviu Andrușcă, Marius Prelipceanu, Lucian-Ionel Cioca, Daniela Lucia Chicet, Ancuța Mirela Radu and Nicanor Cimpoeșu

Appl. Sci. 2024, 14(23), 10877; https://doi.org/10.3390/app142310877 - 24 Nov 2024

Cited by 3 | Viewed by 1200

Abstract

Ceramic materials as coatings are known to have very good corrosion resistance properties compared to metallic or organic coatings, regardless of environmental conditions. The following samples were used for the experiments: an initial steel substrate and Al₂O₃ + YSZ (12.5%; [...] Read more.

Ceramic materials as coatings are known to have very good corrosion resistance properties compared to metallic or organic coatings, regardless of environmental conditions. The following samples were used for the experiments: an initial steel substrate and Al₂O₃ + YSZ (12.5%; 25% and 37.5% wt) atmospheric plasma spray-coated samples. The open circuit potential showed similar average values for all samples coated with ceramic layers, which were slightly higher than the potential of the original uncoated sample. The corrosion current densities (i_corr) of all plasma jet sputter-coated systems were very similar and significantly lower than those of the original material. Corrosion rates were much lower in the coated systems due to the chemical inertness of the ceramic coatings, particularly alumina- and zirconia-based coatings. It was observed that ceramic layers improve the corrosion resistance of the metallic material, especially at higher percentages of YSZ in the plasma spray-deposited complex layer. The porosity of the sputter-deposited layers reduced their corrosion resistance due to the contact between the electrolyte solution and the metal substrate created by the interconnection of the pores. The complex equivalent electrical circuit chosen for the analysis of the values led to results in accordance with the experimental parameters. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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Review

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15 pages, 2052 KiB

Open AccessReview

Application of Areal Topography Parameters in Surface Characterization

by Vesna Alar, Andrej Razumić, Biserka Runje, Ivan Stojanović, Marin Kurtela and Branko Štrbac

Appl. Sci. 2025, 15(12), 6573; https://doi.org/10.3390/app15126573 - 11 Jun 2025

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Abstract

This review paper provides a comprehensive overview of selected 3D surface texture parameters defined by ISO 25178-2, with a focus on their metrological aspects in high-resolution measurements using atomic force microscopy (AFM). The parameters Sa, Sz, Sq, Sdq, and [...] Read more.

This review paper provides a comprehensive overview of selected 3D surface texture parameters defined by ISO 25178-2, with a focus on their metrological aspects in high-resolution measurements using atomic force microscopy (AFM). The parameters Sa, Sz, Sq, Sdq, and Sdr are analyzed in terms of their practical application, sensitivity to measurement conditions, and role in assessing surface functionality. Through a review of the literature and simulations of surface profiles with controlled geometric variations, the study demonstrates how the selected parameters respond to changes in step pitch, step width, slope, and lateral calibration errors. Experimental AFM measurements performed on a certified step height standard further illustrate the impact of calibration on the quality of measurement results. Special emphasis is placed on the importance of evaluating measurement uncertainty. The results confirm the need for rigorous instrument calibration and uncertainty assessment to ensure reliable and comparable surface characterization across different instruments and laboratories. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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34 pages, 4100 KiB

Open AccessReview

Crosslinking Approaches for Polyethylene Imine (PEI) and Its Uses in Adsorption of Heavy Metals, Dyes, and Carbon Dioxide

by Ashika Chandra, Ashneel Ajay Singh, Surendra Prasad, Mats R. Andersson and Desta Gedefaw

Appl. Sci. 2025, 15(9), 4767; https://doi.org/10.3390/app15094767 - 25 Apr 2025

Viewed by 2567

Abstract

Polyethylene imine (PEI) is a synthetic water-soluble and nitrogen-rich polymer with an ethylene amine repeating unit. It exists in a linear or branched forms and finds applications in various areas. PEI is often chemically modified by crosslinking reactions using molecular and polymeric crosslinkers [...] Read more.

Polyethylene imine (PEI) is a synthetic water-soluble and nitrogen-rich polymer with an ethylene amine repeating unit. It exists in a linear or branched forms and finds applications in various areas. PEI is often chemically modified by crosslinking reactions using molecular and polymeric crosslinkers (e.g., trichlorotriazine, epichlorohydrin, ethylene glycol diglycidyl ether, poly(ethylene glycol) diglycidyl ether, etc.) to increase its stability and reduce its water solubility. PEI (pristine/crosslinked) has a strong affinity for metal cations (e.g., Cu²⁺, Au³⁺, Pb²⁺, etc.), where the nitrogen atoms interact with the metal ions, and hence is suitable to remove metals from water with high efficiency. A thin film of crosslinked PEI on substrates can be prepared and finds diverse applications such as in removing metals and dyes, and biofouling prevention in the marine environment. The copper ion, as an example, can be stored (adsorbed) in a thin film of crosslinked PEI on a carbon cloth substrate, which can be released to water by passing an electric current through the film or with an acid treatment. It has also been reported that crosslinked PEI and composite materials can be used for the adsorption of dyes and gases such as CO₂ and SO₂ from the environment. The performance of pristine/composite/crosslinked PEI in gas, metal ion, and dye adsorption is affected by several factors. The focus of this review is to discuss the different reactions used to crosslink PEI and review the properties of the crosslinked materials and their applications. Studies have shown that the properties of the crosslinked PEI and hence its success in capturing metal ions, dyes, and CO₂ is dependent not only on the type of crosslinker but also on the degree of crosslinking. Full article

(This article belongs to the Special Issue Feature Papers in 'Surface Sciences and Technology' Section, 3rd Edition)

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