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Coatings, Volume 12, Issue 8 (August 2022) – 192 articles

Cover Story (view full-size image): Common polyacrylate latex coatings suffer from moisture and water sensitivity, which often limits their practical application in the field of high-performance material protection. Several approaches can be used to improve the water resistance, wettability, and surface properties of latex coating films. Fluorinated monomer copolymerization, incorporation of polymerizable emulsifiers, and covalent crosslinking represent the most effective ones. Highly water-resistant and hydrophobic polyacrylate latex coatings that possess a self-healing ability can be prepared, provided that the polymerizable emulsifier and the fluorinated monomer are employed in the latex synthesis, along with the intra- and interparticle covalent crosslinking. View this paper
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18 pages, 6162 KiB  
Article
Deep Learning-Based Spectrum Reconstruction Method for Raman Spectroscopy
by Qian Zhou, Zhiyong Zou and Lin Han
Coatings 2022, 12(8), 1229; https://doi.org/10.3390/coatings12081229 - 22 Aug 2022
Cited by 1 | Viewed by 2706
Abstract
Raman spectroscopy, measured by a Raman spectrometer, is usually disturbed by the instrument response function and noise, which leads to certain measurement error and further affects the accuracy of substance identification. In this paper, we propose a spectral reconstruction method which combines the [...] Read more.
Raman spectroscopy, measured by a Raman spectrometer, is usually disturbed by the instrument response function and noise, which leads to certain measurement error and further affects the accuracy of substance identification. In this paper, we propose a spectral reconstruction method which combines the existing maximum a posteriori (MAP) method and deep learning (DL) to recover the degraded Raman spectrum. The proposed method first employs the MAP method to reconstruct the measured Raman spectra, so as to obtain preliminary estimated Raman spectra. Then, a convolutional neural network (CNN) is trained by using the preliminary estimated Raman spectra and the real Raman spectra to learn the mapping from the preliminary estimated Raman spectra to the real Raman spectra, so as to achieve a better spectral reconstruction effect than merely using the MAP method or a CNN. To prove the effectiveness of the proposed spectral reconstruction method, we employed the proposed method and some traditional spectral reconstruction methods to reconstruct the simulated and measured Raman spectra, respectively. The experimental results show that compared with traditional methods, the estimated Raman spectra reconstructed by the proposed method are closer to the real Raman spectra. Full article
(This article belongs to the Special Issue Optical Thin Film and Photovoltaic (PV) Related Technologies)
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14 pages, 1376 KiB  
Review
Dental Ceramics: Fabrication Methods and Aesthetic Characterization
by Jefferson David Melo de Matos, Guilherme Rocha Scalzer Lopes, Daher Antonio Queiroz, Leonardo Jiro Nomura Nakano, Nathália Carvalho Ramos Ribeiro, Adriano Baldotto Barbosa, Lilian Costa Anami and Marco Antonio Bottino
Coatings 2022, 12(8), 1228; https://doi.org/10.3390/coatings12081228 - 22 Aug 2022
Cited by 11 | Viewed by 6633
Abstract
This study aimed to describe different staining protocols for the main dental ceramics. A bibliographic search was conducted in the main health databases PubMed and Scholar Google, in which 100 studies published were collected. In vitro and in silico studies, case reports, and [...] Read more.
This study aimed to describe different staining protocols for the main dental ceramics. A bibliographic search was conducted in the main health databases PubMed and Scholar Google, in which 100 studies published were collected. In vitro and in silico studies, case reports, and systematic and literature reviews, on ceramic materials, were included. Therefore, articles that did not deal with the topic addressed were excluded. Ceramics can be classified into glass-matrix ceramics (etchable), polycrystalline (non-etchable), and hybrid ceramics. In this context, different fabrication methods, method indications, and characterization layers can be used for each ceramic group and numerous protocols differ according to the choice of material. Several ceramic systems are available, thus professionals in the prosthetic area need constant updates on dental ceramic restorations and their proper characterizations. Full article
(This article belongs to the Special Issue Preparation and Application of Multifunctional Ceramic Materials)
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38 pages, 14607 KiB  
Review
Bifunctional Electrocatalysts Materials for Non-Aqueous Li–Air Batteries
by Guanghui Yue, Zheyu Hong, Yongji Xia, Tianlun Yang and Yuanhui Wu
Coatings 2022, 12(8), 1227; https://doi.org/10.3390/coatings12081227 - 22 Aug 2022
Cited by 6 | Viewed by 2132
Abstract
Rechargeable lithium–air batteries (LABs), particularly the nonaqueous form, are demonstrated as the next-generation energy conversion and storage equipment for many applications. The air cathode has been certified as one of the critical aspects to affect the full performance of the LABs. At present, [...] Read more.
Rechargeable lithium–air batteries (LABs), particularly the nonaqueous form, are demonstrated as the next-generation energy conversion and storage equipment for many applications. The air cathode has been certified as one of the critical aspects to affect the full performance of the LABs. At present, the main challenge for the commercial application of air cathode is to exploit some new cathode catalysts with lower prices, higher efficiency, and better stability. In the last decade, tremendous efforts have been dedicated to developing new structure design and fabrication processes of the cathode materials to promote the full capability of the LABs. The recent research progress of bifunctional cathode catalysts for LABs, including the main improvement strategies and performance of cathode materials, is introduced in this paper. Besides, related technical challenges are analyzed, and possible resolving strategies for the challenges to develop the nonaqueous Li–air battery catalytic cathodes are elaborated on in this review. Full article
(This article belongs to the Special Issue Advances in Nanostructured Thin Films and Coatings)
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18 pages, 6103 KiB  
Article
Structural Optimization of Sorghum Straw Powder/ZnO/PVA Nanocomposite Films
by Juan Li, Guantao Zhang and Dongjie Zhang
Coatings 2022, 12(8), 1226; https://doi.org/10.3390/coatings12081226 - 22 Aug 2022
Cited by 2 | Viewed by 1679
Abstract
This study sought to improve the utilization of sorghum straw resources and promote the industrial production of new biomass materials. Herein, we fabricated SSP/ZnO/PVA nanocomposite films from sorghum straw powder (SSP), corn starch, polyvinyl alcohol (PVA), and nanostructured ZnO via the casting method. [...] Read more.
This study sought to improve the utilization of sorghum straw resources and promote the industrial production of new biomass materials. Herein, we fabricated SSP/ZnO/PVA nanocomposite films from sorghum straw powder (SSP), corn starch, polyvinyl alcohol (PVA), and nanostructured ZnO via the casting method. Then, we used response surface methodology to examine the effects of the mass concentrations of SSP, glycerol (Gly), and nanostructured ZnO, as well as the starch–PVA mass ratio on the tensile strength (TS) and water vapor permeability (WVP) of the SSP/ZnO/PVA nanocomposite films. The optimum preparation conditions were as follows: SSP mass concentration of 2.0 g/150 mL, Gly mass concentration of 2.5 g/150 mL, starch–PVA mass ratio of 6:4.5, and nanostructured ZnO mass concentration of 0.7 g/150 mL. The TS and WVP of the prepared films were 47.57% higher and 27.07% lower, respectively, than those of ZnO/PVA composite films without SSP. Scanning electron microscopy and atomic force microscopy showed that the SSP/ZnO/PVA nanocomposite films had smooth surfaces and dense cross-sections, without obvious delamination or phase separation. Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analyses revealed that SSP was highly compatible with the ZnO/PVA matrix. Thus, SSP addition could improve the crystallinity, thermal stability, and matrix interactions of SSP/ZnO/PVA nanocomposite films. Full article
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19 pages, 7230 KiB  
Article
Substitution Experiment of Biodegradable Paper Mulching Film and White Plastic Mulching Film in Hexi Oasis Irrigation Area
by Yiming Zhao, Fangyuan Zhang, Lu Li, Xiangjun Yang, Fengwei Zhang, Wuyun Zhao and Qiang He
Coatings 2022, 12(8), 1225; https://doi.org/10.3390/coatings12081225 - 22 Aug 2022
Cited by 7 | Viewed by 2333
Abstract
Biodegradable paper mulch has the advantages of being easily degradable and environmentally benign, but its own performance and adaptability to harsh environments have not been tested. This paper uses scanning electron microscopy and three-dimensional morphometry to microscopically characterize biodegradable paper mulch and white [...] Read more.
Biodegradable paper mulch has the advantages of being easily degradable and environmentally benign, but its own performance and adaptability to harsh environments have not been tested. This paper uses scanning electron microscopy and three-dimensional morphometry to microscopically characterize biodegradable paper mulch and white plastic mulch. To analyze and compare their mechanical and hydrophobic properties, and weather resistance, the two mulches were measured through tensile tear load and static contact angle. A comparative analysis of the effect of mulching in the dry crop area of the Hexi Corridor was conducted by comparing the growth index, farm water heat, soil oxygen content, and yield using maize and flax. The test results show that biodegradable paper mulch films were slightly inferior to traditional white mulch films in terms of mechanical and hydrophobic properties, with inadequate insulation and moisture retention, but better in terms of aging resistance, soil oxygen content, and crop insulation and water storage capacity in the middle and growth stages. White mulch film had a better yield enhancement effect on maize, while with biodegradable paper mulch film, this was more significant with flax. Full article
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33 pages, 4988 KiB  
Review
Research Progress of Self-Cleaning, Anti-Icing, and Aging Test Technology of Composite Insulators
by Qiang He, Wenjie He, Fangyuan Zhang, Yiming Zhao, Lu Li, Xiangjun Yang and Fengwei Zhang
Coatings 2022, 12(8), 1224; https://doi.org/10.3390/coatings12081224 - 22 Aug 2022
Cited by 6 | Viewed by 2608
Abstract
Composite insulators are widely used in power systems because of their advantages of light weight, good pollution resistance, and high mechanical strength. With the increasingly serious environmental pollution problem, especially in winter at high latitudes, composite insulators are easily affected by fog, bird [...] Read more.
Composite insulators are widely used in power systems because of their advantages of light weight, good pollution resistance, and high mechanical strength. With the increasingly serious environmental pollution problem, especially in winter at high latitudes, composite insulators are easily affected by fog, bird droppings, algae, and icing. Long-term exposure to the outdoor insulator surface will cause aging, which will then pose ae potential safety hazard to the stable operation of insulators. Therefore, the self-cleaning, anti-icing, and aging test technologies of composite insulators are particularly important. This paper introduces the research progress and current situation of self-cleaning, anti-icing surface preparation, and aging test technology of composite insulators, and looks forward to the future development of composite insulators. Full article
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14 pages, 5104 KiB  
Article
Characterization and Wear Behaviors of Electrodeposited Ni-MoS2/SiC Composite Coating
by Yutao Yan, Lifeng Lu, Yuqiu Huo and Yong Zhao
Coatings 2022, 12(8), 1223; https://doi.org/10.3390/coatings12081223 - 21 Aug 2022
Cited by 2 | Viewed by 1613
Abstract
Among the preparation methods of functional coatings, the electrodeposition technique has attracted much attention due to its advantages of economy, high efficiency and good structural adaptability. The application of aluminum alloy materials is greatly limited due to their poor friction reduction and wear [...] Read more.
Among the preparation methods of functional coatings, the electrodeposition technique has attracted much attention due to its advantages of economy, high efficiency and good structural adaptability. The application of aluminum alloy materials is greatly limited due to their poor friction reduction and wear resistance. Therefore, to enhance the tribological behaviors of aluminum alloy materials, the Ni-MoS2, Ni-SiC and Ni-MoS2/SiC composite coatings were prepared on the 2218 aluminum alloy by an electrodeposition technique. The prepared composite coating samples exhibited a compact and dense microstructure, which was consistent with the result of their high microhardness. No obvious microcracks and defects appeared at the interfaces, indicating that the composite coating samples had good adhesion to the substrates and can effectively improve the frictional shear resistance. The results of wear experiment showed that the wear rate, friction coefficient and friction response time of all composite coating samples were lower than that of the substrate sample. However, the friction reduction and wear resistance of the same composite coating sample were not consistent. The friction coefficient of the Ni-MoS2 composite coating sample was the lowest, and the wear rate of the Ni-SiC composite coating sample was the lowest. According to the worn surface observations, the wear mechanism of composite coating samples was mainly characterized by the mild abrasive wear, flake spalling, tearing and pits caused by particle shedding, and the substrate sample showed a severe adhesive wear and abrasive wear. Full article
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17 pages, 5022 KiB  
Article
Fatigue and Life Prediction of S135 High-Strength Drill Pipe Steel under Tension–Torsion Multiaxial Loading
by Sheji Luo, Ming Liu, Lihong Han and Yuna Xue
Coatings 2022, 12(8), 1222; https://doi.org/10.3390/coatings12081222 - 21 Aug 2022
Cited by 1 | Viewed by 2118
Abstract
This paper investigates the fatigue behavior of S135 high-strength drill pipe steel under tension–torsion multiaxial loading. Based on the concept of critical plane during fatigue, the fatigue model under the combined loading of tension–torsion is established. The proposed model is validated, and the [...] Read more.
This paper investigates the fatigue behavior of S135 high-strength drill pipe steel under tension–torsion multiaxial loading. Based on the concept of critical plane during fatigue, the fatigue model under the combined loading of tension–torsion is established. The proposed model is validated, and the predicted results are in good agreement with the experimental testing results. The maximum relative errors between the estimation and the experiment are mostly within the range of factor two to three for proportional, and 90° non-proportional tension–torsion loading. Meanwhile, the failure mechanism is also discussed through fracture analysis. Full article
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15 pages, 5260 KiB  
Article
Effect of Groove Width on Micromachine Groove Texture Tribology Characteristics of 0Cr17Ni7Al
by Liguang Yang, Wensuo Ma, Fei Gao and Shiping Xi
Coatings 2022, 12(8), 1221; https://doi.org/10.3390/coatings12081221 - 21 Aug 2022
Cited by 5 | Viewed by 1522
Abstract
Friction and wear are the main forms of material surface failure. Surface modification is very effective in friction reduction and wear resistance systems. Therefore, as a method of surface modification to improve the tribological properties of materials, surface texture has been widely loved [...] Read more.
Friction and wear are the main forms of material surface failure. Surface modification is very effective in friction reduction and wear resistance systems. Therefore, as a method of surface modification to improve the tribological properties of materials, surface texture has been widely loved by scholars. However, most scholars use laser and other processing methods to prepare the surface texture. Although these processing methods have a high preparation efficiency, they cannot obtain a surface texture with high dimensional accuracy due to their non-contact processing characteristics. Moreover, previous studies on different surface texture preparation methods are insufficient. Scholars have not fully studied the size parameters of surface modification. Micromachining is a contact machining method. It has high dimensional accuracy. Therefore, the surface groove texture of 0Cr17Ni7Al material commonly used in sliding bearings was prepared by micromachining in this paper. Under dry friction conditions, the effects of different groove widths on the tribological properties of surface texture were studied. The results show that the friction coefficient at the 0.6 mm-wide groove texture is the lowest, σ = 0.632. The minimum wear rate is ω = 3.351 × 10−4 mm3/(N·mm). The friction coefficient and wear rate of all groove textures are lower than those of untextured surfaces. It can be judged that the groove texture prepared by micromachining has good friction reduction and wear resistance under the same load, time, and linear speed. With the increase of the groove width, the friction coefficient and wear rate of groove texture decrease first and then increase. Full article
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12 pages, 3381 KiB  
Article
Adhesion Strength of Amorphous Carbon Films Deposited on a Trench Sidewall
by Kyohei Toyoshima, Abdelrahman Farghali and Junho Choi
Coatings 2022, 12(8), 1220; https://doi.org/10.3390/coatings12081220 - 20 Aug 2022
Viewed by 1698
Abstract
Hydrogenated amorphous carbon (a-C:H) films were deposited on the sidewall of 3-mm-wide stainless steel or Si trench, and the adhesion strength of the films was evaluated using a micro-scratch tester. Particularly, the effects of carbon ion implantation and Si-containing interlayer (a-SiCx:H) as the [...] Read more.
Hydrogenated amorphous carbon (a-C:H) films were deposited on the sidewall of 3-mm-wide stainless steel or Si trench, and the adhesion strength of the films was evaluated using a micro-scratch tester. Particularly, the effects of carbon ion implantation and Si-containing interlayer (a-SiCx:H) as the pretreatments on the adhesion strength of the a-C:H films prepared on the trench sidewall were investigated. It was found that both carbon ion implantation and interlayer improved the adhesion strength of the a-C:H films deposited on the trench sidewalls. In addition, the carbon ion implantation dominated the adhesion strength of the a-C:H films for the Si substrates, and the interlayer for the stainless steel substrates. In the case of the stainless steel substrates, the carbon was accumulated on the surface of the trench sidewall instead of implantation, whereas the carbon ions were implanted to the Si substrates on the trench sidewall to form a mixing layer. The a-SiCx:H interlayer forms Fe–Si bonds between the stainless steel substrate and the interlayer, which is thought to improve the adhesion strength. It was also found that there is a negative correlation between the trench depth and the adhesion strength regardless of the pretreatment methods. Full article
(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)
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17 pages, 56649 KiB  
Article
Experimental Research on Properties of UHPC Based on Composite Cementitious Materials System
by Fansheng Kong, Fang Xu, Qiuyang Xiong, Songji Xu, Xiang Li, Wenxiang Fu and Zhijiong Guo
Coatings 2022, 12(8), 1219; https://doi.org/10.3390/coatings12081219 - 20 Aug 2022
Cited by 2 | Viewed by 1525
Abstract
As concrete damage occurs frequently in the transition zone of bridge expansion joints, this paper discussed ultra-high-performance concrete (UHPC) based on composite cementitious materials system for the repair of the bridge expansion joint transition zone. The performance of UHPC based on composite cementitious [...] Read more.
As concrete damage occurs frequently in the transition zone of bridge expansion joints, this paper discussed ultra-high-performance concrete (UHPC) based on composite cementitious materials system for the repair of the bridge expansion joint transition zone. The performance of UHPC based on composite cementitious materials system was studied by combining the macroscopic properties and microstructure of the material with the hydration mechanism of the cementitious material. The influence of sulphate aluminum cement (SAC) on composite cementitious materials system was studied. The experimental results showed that the appropriate amount of SAC can effectively reduce the setting time in the composite cementitious materials system. While SAC caused the strength to decrease, it has little effect on the mechanical properties of the composite cementitious materials system. When the ratio of SAC is 0.1 in the composite cementitious materials system, the setting time is shortened with maintaining the dense micro-structure observed by the SEM images. It can achieve fast hardening and have good early mechanical performance while retaining excellent long-term properties. Therefore, the addition of SAC can effectively make it possible to apply the excellent performance of UHPC for the repair of highway and bridge. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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19 pages, 8353 KiB  
Article
Erosive Wear Behavior of High-Chromium Cast Iron: Combined Effect of Erodent Powders and Destabilization Heat Treatments
by Annalisa Fortini, Alessio Suman, Nicola Zanini and Giuseppe Cruciani
Coatings 2022, 12(8), 1218; https://doi.org/10.3390/coatings12081218 - 20 Aug 2022
Cited by 5 | Viewed by 1879
Abstract
High-chromium cast irons are frequently used in high-demanding applications, where low production costs and wear performance are key factors. The excellent abrasive resistance of these alloys results from the overall microstructural features, i.e., type, morphology, and distribution of hard primary and secondary carbides, [...] Read more.
High-chromium cast irons are frequently used in high-demanding applications, where low production costs and wear performance are key factors. The excellent abrasive resistance of these alloys results from the overall microstructural features, i.e., type, morphology, and distribution of hard primary and secondary carbides, along with the matrix constituents. Such a microstructure is the result of the chemical composition and solidification process, even though it could be further tuned by heat treatments. These latter are usually performed to destabilize the austenite and to induce the precipitation of secondary carbides. The present study investigates the combined effect of destabilization heat treatment route and erodent powder type on the erosive wear behavior of two commercial hypereutectic white cast irons. The as-received and the heat-treated materials were analyzed through optical and scanning electron microscopy, hardness tests, and X-ray diffraction to determine the relationship between microstructural variations and applied heat treatment. The erosive resistance was evaluated per the ASTM G76 standard in a purpose-built air blast test rig. Experiments were performed considering a raw meal powder, commonly used in cement factories, and Al2O3 as erodent powders. The adopted heat treatments were effective in increasing the overall hardness of the material, but this was not directly related to the erosion resistance. By contrast, the relative hardness ratio, i.e., erodent/target hardness, affects the erosion rate and different behaviors in relation to the softer/harder erodent particles were found. Full article
(This article belongs to the Section Tribology)
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14 pages, 7460 KiB  
Article
The Fabrication of Indium–Gallium–Zinc Oxide Sputtering Targets with Various Gallium Contents and Their Applications to Top-Gate Thin-Film Transistors
by Tsung-Cheng Tien, Jyun-Sheng Wu, Tsung-Eong Hsieh and Hsin-Jay Wu
Coatings 2022, 12(8), 1217; https://doi.org/10.3390/coatings12081217 - 19 Aug 2022
Cited by 1 | Viewed by 1585
Abstract
We prepared amorphous indium–gallium–zinc oxide (a-IGZO) thin films with various Ga content ratios and investigated their feasibility as the active channel layers of top-gate thin-film transistors (TFT). First, the 2-inch IGZO sputtering targets with stoichiometric ratios of InGaZn2O5 [...] Read more.
We prepared amorphous indium–gallium–zinc oxide (a-IGZO) thin films with various Ga content ratios and investigated their feasibility as the active channel layers of top-gate thin-film transistors (TFT). First, the 2-inch IGZO sputtering targets with stoichiometric ratios of InGaZn2O5, InGaZnO4, and InGa2ZnO5.5 were fabricated using In2O3, Ga2O3, and ZnO oxide powders as raw materials via sintering treatments at temperatures ranging from 900 °C to 1300 °C for 6 h or 8 h. X-ray diffraction analysis indicated that the InGaZn2O5 and InGaZnO4 targets are single-phase structures whereas the InGa2ZnO5.5 target is a two-phase structure. Hall effect measurement indicated that the a-InGaZn2O5 and a-InGaZnO4 layers possess a carrier concentration (N) of about 1019 cm−3 and a resistivity (ρ) of about 10−2 Ω·cm; however, the N of the a-InGa2ZnO5.5 layer is only 1017 cm−3, and the ρ is about 1 to 4 Ω·cm. Moreover, the a-InGaZn2O5 layer exhibited the highest Hall-effect mobility (μHall) of 21.17 cm2·V−1·sec−1. This indicated that the impedance of Ga3+ ions to carrier migration is the main factor affecting the electrical properties of a-IGZO layers. Ga content in the a-IGZO channel similarly affects the performance of the TFT devices prepared in this study. The annealing at 300 °C for 1 h in an ambient atmosphere was found to significantly improve the electrical properties of the TFT devices. The best performance was observed in the a-InGaZnO4 TFT sample subjected to post-annealing at 300 °C with Vth = −0.85 V, μFE = 8.46 cm2, V−1·sec−1, SS = 2.31, V·decade−1, and Ion/Ioff = 2.9 × 104. Full article
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12 pages, 2444 KiB  
Article
Vertical Growth Dynamics and Multifractality of the Surface of Electropolymerized Poly(o-ethoxyaniline) Thin Films
by Cindel Cavalcante de Souza, Ariamna María Dip Gandarilla, Walter Ricardo Brito, Edgar Aparecido Sanches, Abhijeet Das, Sanjeev Kumar, Robert Saraiva Matos, Ştefan Ţălu and Henrique Duarte da Fonseca Filho
Coatings 2022, 12(8), 1216; https://doi.org/10.3390/coatings12081216 - 19 Aug 2022
Viewed by 1392
Abstract
Electropolymerized poly(o-ethoxyaniline) (POEA) nanostructured thin films were successfully deposited on indium tin oxide (ITO) substrate. The surface dynamic of the films was extensively investigated using morphological and multifractal parameters extracted from the atomic force microscopy (AFM). AFM topographical maps reveal surfaces with different [...] Read more.
Electropolymerized poly(o-ethoxyaniline) (POEA) nanostructured thin films were successfully deposited on indium tin oxide (ITO) substrate. The surface dynamic of the films was extensively investigated using morphological and multifractal parameters extracted from the atomic force microscopy (AFM). AFM topographical maps reveal surfaces with different morphologies as a function of the deposition cycles. The height parameters show that there is greater spatial vertical growth for films deposited with higher cycles of deposition. After five cycles of deposition occurs the formation of a more isotropic surface, while for 15 cycles a less isotropic surface is observed. The Minkowski functionals confirm that morphological aspects of the two films change according to the amount of deposition cycles employed. The POEA surfaces also exhibit a strong multifractal nature with a decrease in the multifractal spectrum width as the number of deposition cycles increases. Our findings prove that deposition cycles can be useful in controlling the vertical growth and surface dynamics of electropolymerized POEA nanostructured samples, which can be useful for improving the fabrication of POEA-coated ITO-based devices. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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11 pages, 1394 KiB  
Article
Biobased Materials for the Development of Biodegradable Slow-Release Fertilizers
by Przemysław Boberski, Kamila Torchała, Hanna Studnik, Jan Wójcik, Marek Główka and Nikodem Kuźnik
Coatings 2022, 12(8), 1215; https://doi.org/10.3390/coatings12081215 - 19 Aug 2022
Viewed by 2508
Abstract
According to the regulations of the European Parliament on fertilizer products, by July 2024, all substances used for coating fertilizers should be biodegradable. A series of coated fertilizers was prepared, which differed in the amount of applied coating layer. The core of the [...] Read more.
According to the regulations of the European Parliament on fertilizer products, by July 2024, all substances used for coating fertilizers should be biodegradable. A series of coated fertilizers was prepared, which differed in the amount of applied coating layer. The core of the composition was granular ammonium nitrate, which contains 27% nitrogen. The effects of the amount of oil layers were examined. The article shows the results of IR testing and Iodine Value of the materials used. The coated fertilizer was evaluated for the release of nutrients under water conditions according to the standard ISO 21263, and the water samples were taken after every day for a 7-day period. The nitrogen content was analysed by elemental analysis. Microscopic pictures of the fertilizer composition were taken before release. The obtained product had potential controlled-release properties and was environmentally friendly. The tested material shows high potential as a component of a two-layer coated fertilizer. This type of fertilizer could be particularly useful in agricultural and horticultural applications. Full article
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9 pages, 3633 KiB  
Article
Efficient Isolation of Circulating Tumor Cells Using Ultra-Convenient Substrates Based on Self-Assembled Hollow MnO2 Nanoparticles
by Rui Li, Yuankun Wang and Tengfei Long
Coatings 2022, 12(8), 1214; https://doi.org/10.3390/coatings12081214 - 19 Aug 2022
Cited by 1 | Viewed by 1324
Abstract
An efficient and active sorting platform of circulating tumor cells (CTCs) is still a challenge in clinical research. In this paper, we design a novel system based on hollow MnO2 nanoparticles for the capture and release of CTCs. Using the self-assembly method, [...] Read more.
An efficient and active sorting platform of circulating tumor cells (CTCs) is still a challenge in clinical research. In this paper, we design a novel system based on hollow MnO2 nanoparticles for the capture and release of CTCs. Using the self-assembly method, we prepared rough MnO2 nanomaterial substrates that provide more binding sites for antibody grafting, increase the contact probability between cells and materials and improve the capture efficiency. The highest capture efficiency was 83.2% under the incubation time of 120 min. The MnO2 nanosubstrate was dissolved by employing a 2 × 10−3 M concentration of oxalic acid to release the captured cells. The cell release efficiency was up to 91.46% with a reaction time of 60 s. The released cells had a strong ability to proliferate after being collected and re-cultured for 24 h. Identifying and counting CTCs from the peripheral blood of breast cancer patients through the three-color immunocytochemistry method proved the effectiveness of our design platform. Such a simple and economical approach provides a promising platform for the capture and release of cells in clinical research. Full article
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15 pages, 3348 KiB  
Article
Preparation of Melamine-Formaldehyde Resin/Rice Husk Powder Coated Epoxy Resin Microcapsules and Effects of Different Microcapsule Contents on the Properties of Waterborne Coatings on Tilia europaea Surface
by Nan Huang, Xiaoxing Yan and Yan Han
Coatings 2022, 12(8), 1213; https://doi.org/10.3390/coatings12081213 - 19 Aug 2022
Cited by 7 | Viewed by 2217
Abstract
With the development of economy and science and technology, people put forward higher standards for the performance of the surface coating of wood products, which requires us to carry out innovative research on the coating. In this work, a kind of microcapsule was [...] Read more.
With the development of economy and science and technology, people put forward higher standards for the performance of the surface coating of wood products, which requires us to carry out innovative research on the coating. In this work, a kind of microcapsule was prepared with melamine-formaldehyde resin/rice husk powder as wall material and epoxy resin as core material. The microcapsules were added to the waterborne acrylic resin coating according to the contents of 0%, 1.0%, 4.0%, 7.0%, 10.0%, 13.0%, 16.0% and 20.0% respectively, and were coated on the surface of the Tilia europaea boards in the form of topcoat. The effects of different contents of microcapsules on the optical properties, mechanical properties and aging resistance of the coating were explored, and the optimal content that can effectively improve the properties of the coating was analyzed. Test results indicated that when the microcapsule content is 7.0%, the comprehensive properties of the coating is optimal. At this time, the color difference of the coating is 6.96, the gloss at 60° is 13.4%, the hardness is 2H, the adhesion grade is 1, and the impact resistance is 12.0 kg·cm. After the aging test, the gloss loss rate decreases, the color difference is 5.69, and the gloss at 60° is 11.6%. The results of aging test show that the coating with epoxy microcapsules has a certain self-healing function. In this study, the microcapsules which can optimize the mechanical properties waterborne coating and prolong the service life of wood were prepared. This can meet the diverse needs of consumers, supply a theoretical reference for the preparation of functional microcapsules, and provide reference value for the functional research of the coating on wood furniture surface. Full article
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16 pages, 7700 KiB  
Article
The In Vitro Impact of Two Scaffold-Type Structure Dental Ceramics on the Viability, Morphology, and Cellular Migration of Pharyngeal Cancer Cells
by Mihai M. C. Fabricky, Robert Cosmin Racea, Ioana Macasoi, Iulia Pinzaru, Cosmin Sinescu, Horatiu Cristian Manea, Laura-Cristina Rusu, Dana Stoian, Roxana Buzatu and Stefania Dinu
Coatings 2022, 12(8), 1212; https://doi.org/10.3390/coatings12081212 - 18 Aug 2022
Viewed by 1367
Abstract
There is a growing trend with respect to the use of ceramic materials in dental practice. With an increase in the number of cases of head and neck cancer, the use of dental implants in these patients is subject to controversy. Consequently, the [...] Read more.
There is a growing trend with respect to the use of ceramic materials in dental practice. With an increase in the number of cases of head and neck cancer, the use of dental implants in these patients is subject to controversy. Consequently, the purpose of the present study was to evaluate the impact of two ceramic materials on the viability, proliferation, migration, and structure of the cytoskeleton and nuclei of pharyngeal cancer cells. Therefore, samples of the two ceramic were immersed in artificial saliva with three different pH values in order to better simulate the natural biological environment. A 21-day immersion period was followed by testing of the saliva on pharyngeal cancer cell line Detroit-562 for its viability, morphology, and migration, as well as its effects on the nucleus and cytoskeleton. The results of the study after stimulation of Detroit-562 cells for 72 h with the three types of artificial saliva in which the ceramic materials were immersed indicated the following: (i) viability of cells did not change significantly, with the percentage of viable cells not falling below 90%; (ii) no morphological changes were recorded, with the shape and number of cells being similar to that of the control cells; (iii) the scratch assay method indicated that the two types of ceramics do not stimulate cell migration; and (iv) fluorescence immunocytochemistry revealed that both the nucleus and the cytoskeleton distributions were unaltered, as they were observed in unstimulated cells. The preliminary results of the study indicate that the investigated ceramic materials did not interact unfavorably with tumor cells when immersed in artificial saliva, thereby supporting the possibility of their safe use in cancer patients. Full article
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12 pages, 6385 KiB  
Article
Characteristics of Thin High Entropy Alloy Films Grown by Pulsed Laser Deposition
by Edwin Alexandru Laszlo, Doina Crăciun, Gabriela Dorcioman, Gabriel Crăciun, Victor Geantă, Ionelia Voiculescu, Daniel Cristea and Valentin Crăciun
Coatings 2022, 12(8), 1211; https://doi.org/10.3390/coatings12081211 - 18 Aug 2022
Cited by 2 | Viewed by 1884
Abstract
Starting from solid-solutions (SS) of AlCoCrFeNix high-entropy alloys (HEAs) that have been produced with high purity constituent elements by vacuum arc remelting (VAR) method varying the nickel molar ratio x from 0.2 to 2.0, we investigated the synthesis of protective thin films [...] Read more.
Starting from solid-solutions (SS) of AlCoCrFeNix high-entropy alloys (HEAs) that have been produced with high purity constituent elements by vacuum arc remelting (VAR) method varying the nickel molar ratio x from 0.2 to 2.0, we investigated the synthesis of protective thin films of HEAs and high-entropy nitrides (HENs) with the aid of the pulsed laser deposition (PLD) system. The structure of all ten available bulk targets have been examined by means of X-Ray Diffraction (XRD), as well as their elemental composition by means of energy dispersion X-ray spectroscopy (EDS). Three targets with nickel molar composition x = 0.4, 1.2 and 2.0 corresponding to BCC, mixed BCC and FCC, and finally FCC structures were used for thin film depositions using a KrF excimer laser. The depositions were performed in residual low vacuum (10−7 mbar) and under N2 (10−4 mbar) at room temperature (RT~25 °C) on Si and glass substrates. The deposited films’ structure was investigated using grazing incidence XRD, their surface morphology, thickness and elemental composition by scanning electron microscopy (SEM), EDS and X-ray photoelectron spectroscopy (XPS), respectively. A homemade four-point probe (4PP) set-up was applied to determine layers electrical resistance. Besides, a Nanoindentation (NI) was employed to test films’ mechanical properties. XRD results showed that all deposited films, regardless of the initial structure of targets, were a mixture of FCC and BCC structures. Additionally, the quantitative and qualitative EDS and XPS results showed that the elemental composition of films was rather close to that of the targets. The depositions under an N2 atmosphere resulted in the inclusion of several percentage nitrogen atoms in a metallic nitride type compound into films, which may explain their higher electrical resistivity. The Young’s modulus, nanohardness and friction coefficient values showed that the deposited films present good mechanical properties and could be used as protective coatings to prevent damage in harsh environments. Full article
(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings)
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12 pages, 3674 KiB  
Article
Realizing Efficient Photoelectrochemical Performance for Well-Designed CdS@ZnIn2S4 Heterostructure Photoanode with Directional Interfacial Charge Transfer Dynamics
by Xianchen Wu, Yu Qian, Gangyang Lv, Liyuan Long, Yong Zhou and Dunhui Wang
Coatings 2022, 12(8), 1210; https://doi.org/10.3390/coatings12081210 - 18 Aug 2022
Viewed by 1815
Abstract
Designing a heterostructure photoanode with an appropriate band alignment, a beneficial charge migration pathway, and an adequate interfacial coupling is crucial for photoelectrochemical (PEC) energy conversion. Herein, we fabricate a hetero-nanostructure photoanode with CdS nanorods (CdS NRs) and two-dimensional (2D) ZnIn2S [...] Read more.
Designing a heterostructure photoanode with an appropriate band alignment, a beneficial charge migration pathway, and an adequate interfacial coupling is crucial for photoelectrochemical (PEC) energy conversion. Herein, we fabricate a hetero-nanostructure photoanode with CdS nanorods (CdS NRs) and two-dimensional (2D) ZnIn2S4 nanosheets (ZIS NSs) via a two-step in situ growth method on FTO glass to acquire a sufficient interfacial contact between two semiconductors. Based on their electronic band structures, the CdS is designed to be firstly grown on FTO to act as a photoelectron transport layer and 2D ZIS is further fabricated on the CdS as a photohole accumulation layer to directly contact the electrolyte. Benefitting from the Type II band alignment between the CdS and ZIS, such a heterostructure significantly enhances the separation efficiency and prolongs the lifetime of photocarriers. More importantly, it ensures that photoholes accumulate on the 2D ZIS with a highly exposed surface area for an oxidation reaction at the surface-active sites, while the photoelectrons transfer to counter electrode for hydrogen evolution. The optimum CdS@ZIS heterostructure photoanode exhibits a superior PEC performance with a photocurrent of 4.19 mA/cm2 at 1.23 VRHE (two times that of the CdS and eight times that of ZIS) and an applied bias photo-to-current efficiency (ABPE) of 1.93% at 0.49 VRHE. This work can inspire the future design of heterostructure photoanodes for highly efficient solar energy conversion. Full article
(This article belongs to the Special Issue Optical Thin Film and Photovoltaic (PV) Related Technologies)
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15 pages, 12820 KiB  
Article
Effect of WC on Microstructure and Wear Resistance of Fe-Based Coating Fabricated by Laser Cladding
by Angang Wei, Yun Tang, Tong Tong, Fang Wan, Shaoshuai Yang and Kaiming Wang
Coatings 2022, 12(8), 1209; https://doi.org/10.3390/coatings12081209 - 18 Aug 2022
Cited by 10 | Viewed by 2161
Abstract
As the core component of the wind turbine transmission chain, the wind power gear plays a vital role in the safe and efficient operation of the whole machine. Wind power gears are subjected to varying degrees of wear on their contact surfaces due [...] Read more.
As the core component of the wind turbine transmission chain, the wind power gear plays a vital role in the safe and efficient operation of the whole machine. Wind power gears are subjected to varying degrees of wear on their contact surfaces due to alternating load impacts. For wind power gear repair and remanufacturing, laser cladding technology is proposed on the wind power gearbospline shaft. The effect of tungsten carbide (WC) addition on the laser-clad Fe-based coatings was investigated in this study. The morphology and composition of the composite coatings formed with different proportions of WC were studied using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The microhardness and wear resistance were measured with a digital microhardness tester and a wear testing machine, respectively. The coatings were compact with no apparent cracks or pores and the microstructures of the regions above the fusion zone gradually changed from planar crystal to columnar crystal and cellular crystal, while the middle and upper parts of the coating mainly consisted of equiaxed crystals. The microhardness of the coatings gradually increased with the increase of WC content. The coating with 16% WC addition reached a maximum microhardness of 826.2 HV. The increase of WC content improved the wear resistance of the laser-clad Fe-based composite coatings. The wear mechanism of the coatings was mainly abrasive wear, along with slight adhesion wear and oxidative wear. Full article
(This article belongs to the Section Laser Coatings)
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10 pages, 3596 KiB  
Article
Simulation of Mushroom Nanostructures with Ag Nanoparticles for Broadband and Wide-Angle Superabsorption
by Jinshuang Wu, Mingzhao Ouyang, Bowei Yang and Yuegang Fu
Coatings 2022, 12(8), 1208; https://doi.org/10.3390/coatings12081208 - 18 Aug 2022
Cited by 1 | Viewed by 1393
Abstract
Metal nanoparticles (NPs) concentrate the energy of incident photons through plasmon resonance excitation, which allows scattering into a substrate with a high refractive index, and the radiated energy from this excitation significantly increases the optical absorption of the substrate. In this work, the [...] Read more.
Metal nanoparticles (NPs) concentrate the energy of incident photons through plasmon resonance excitation, which allows scattering into a substrate with a high refractive index, and the radiated energy from this excitation significantly increases the optical absorption of the substrate. In this work, the effect of Ag NPs on the absorption capacity of mushroom-nanostructured Si metasurfaces was analyzed using the finite-difference time-domain method. It was observed that the absorbance in the metasurfaces with Ag NPs increased from 90.8% to 98.7% compared with nanostructured Si metasurface without NPs. It was shown that the plasmon resonance effect of Ag NPs enlarged the range of the FP cavity by about 10 times, and the electric field strength E2 increased by about four times through the combination of Ag NP and Si absorbers. Meanwhile, the effect of randomly distributed nanostructures on the absorption properties of Si metasurfaces was simulated. Additionally, the nanostructured surface with Ag NPs was insensitive to angle, which encourages the design of broadband and wide-angle superabsorption nanostructures. Full article
(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)
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22 pages, 4794 KiB  
Article
Structure and Corrosion Resistance of Coatings Obtained by the Batch Double Hot Dip Method in Eutectoid ZnAl Bath with the Addition of Mg and Si
by Henryk Kania
Coatings 2022, 12(8), 1207; https://doi.org/10.3390/coatings12081207 - 18 Aug 2022
Cited by 4 | Viewed by 2053
Abstract
The article presents the results of the research determining the synergistic effect of Mg and Si additives in the ZnAl23 bath on the microstructure (SEM), growth kinetics, and corrosion resistance of coatings obtained by the batch double hot dip method. On the basis [...] Read more.
The article presents the results of the research determining the synergistic effect of Mg and Si additives in the ZnAl23 bath on the microstructure (SEM), growth kinetics, and corrosion resistance of coatings obtained by the batch double hot dip method. On the basis of the research on the chemical composition in micro-regions (EDS) and the research on the phase composition (XRD), the structural components of the coatings with a content of 3 and 6 wt.% Mg and 0.2–0.4 wt.% Si were identified. The corrosion resistance of the coatings was compared with that of the reference coating obtained in the ZnAl23Si0.4 bath in the neutral salt spray test (EN ISO 9227), and the test with sulfur dioxide in a humid atmosphere (EN ISO 6988). The parameters of electrochemical corrosion of the coatings were determined. This allowed for the conclusion that the addition of Mg and Si to the ZnAl23 bath improved the microstructural uniformity of the coating. In the area of the diffusion layer, the presence of the FeAl3 intermetallic phase was found, while in the outer layer the dendrite of the Al-rich solution with interdendritic spaces, where it locates areas of Zn-rich solution, eutectic Zn/MgZn2 or phase separation MgZn2 and Mg2Si are located. Additions of Mg and Si stabilize the kinetics of the coating’s growth, and its course is parabolic. The conducted corrosion tests showed better corrosion resistance of the coatings obtained in the bath with Mg addition compared to the reference coating obtained in the ZnAl23Si bath. The increase in corrosion resistance results from the presence of a more anodic MgZn2 phase, which, however, may be weakened by the presence of Mg2Si phase precipitates. Full article
(This article belongs to the Special Issue Corrosion and Anticorrosion of Alloys/Metals)
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12 pages, 4819 KiB  
Article
Fabrication and Characterization of P-Type Semiconducting Copper Oxide-Based Thin-Film Photoelectrodes for Solar Water Splitting
by Chih-Jui Chang, Chih-Wei Lai, Wei-Cheng Jiang, Yi-Syuan Li, Changsik Choi, Hsin-Chieh Yu, Shean-Jen Chen and YongMan Choi
Coatings 2022, 12(8), 1206; https://doi.org/10.3390/coatings12081206 - 17 Aug 2022
Cited by 3 | Viewed by 2672
Abstract
Solar light-driven hydrogen by photocatalytic water splitting over a semiconductor photoelectrode has been considered a promising green energy carrier. P-type semiconducting copper oxides (Cu2O and CuO) have attracted remarkable attention as an efficient photocathode for photoelectrochemical (PEC) water splitting because of [...] Read more.
Solar light-driven hydrogen by photocatalytic water splitting over a semiconductor photoelectrode has been considered a promising green energy carrier. P-type semiconducting copper oxides (Cu2O and CuO) have attracted remarkable attention as an efficient photocathode for photoelectrochemical (PEC) water splitting because of their high solar absorptivity and optical band gaps. In this study, CuO thin films were prepared using the sol-gel spin coating method to investigate the effects of aging time and layer dependency. Electrodeposition was also applied to fabricate Cu2O thin films. Cu2O thin films annealed at 300 °C are a hetero-phase system composed of Cu2O and CuO, while those at 400 °C are fully oxidized to CuO. Thin films are characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-VIS), Fourier transform infrared spectroscopy (FTIR), spectroscopic ellipsometry (SE), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman microscopy. The hetero-phase thin films increase the photoconversion efficiency compared to Cu2O. Fully oxidized thin films annealed at 400 °C exhibit a higher efficiency than the hetero-phase thin film. We also verified that CuO thin films fabricated using electrodeposition show slightly higher efficiency than the spin coating method. The highest photocurrent of 1.1 mA/cm2 at 0.10 V versus RHE was measured for the fully oxidized CuO thin film under one-sun AM1.5G illumination. This study demonstrates a practical method to fabricate durable thin films with efficient optical and photocatalytic properties. Full article
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16 pages, 18049 KiB  
Article
Dissolution Behavior of Different Alumina Phases within Plasma Electrolytic Oxidation Coatings
by Frank Simchen, Roy Morgenstern, Steffen Clauß, Thomas Mehner and Thomas Lampke
Coatings 2022, 12(8), 1205; https://doi.org/10.3390/coatings12081205 - 17 Aug 2022
Cited by 3 | Viewed by 1351
Abstract
The influence of chemical redissolution in the PEO layer-growth equilibrium on aluminum is evaluated differently in literature. In order to estimate whether and to what extent various alumina modifications could be affected by redissolution processes during PEO, immersion experiments were carried out on [...] Read more.
The influence of chemical redissolution in the PEO layer-growth equilibrium on aluminum is evaluated differently in literature. In order to estimate whether and to what extent various alumina modifications could be affected by redissolution processes during PEO, immersion experiments were carried out on PEO coatings in model electrolytes of different alkalinity and silicate concentration. Their composition was determined spectroscopically before and after the experiments. The layers were characterized by XRD before and after the tests and examined at affected and unaffected zones using SEM, EDX, and EBSD. The results show that chemical oxide dissolution can only be observed at the layer/substrate interface and that primarily amorphous alumina is affected. This process is intensified by higher alkalinity and inhibited by silicate additives. The crystalline Al2O3 modifications show no significant attack by the electrolytes used. Transferring these observations to plasma electrolytic oxidation, they allow the conclusion that the electrochemically active zone in the pore ground of discharge channels interacts with the electrolytic and electrical process parameters throughout the entire PEO procedure. Influences of bath alkalinity and silicate content on layer growth rates are to be understood as impact on the passivation processes at the layer/substrate interface rather than chemical redissolution. Full article
(This article belongs to the Special Issue Plasma Electrolytic Oxidation (PEO) Coatings, 2nd Edition)
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17 pages, 2508 KiB  
Article
Integrative Approach of MAP and Active Antimicrobial Packaging for Prolonged Shelf-Life of Composite Bottle Gourd Milk Cake
by Rekha Chawla, Sivakumar Shanmugam, Jasbir Singh Bedi, Selvamuthukumaran, Deep N. Yadav and Rahul Anurag
Coatings 2022, 12(8), 1204; https://doi.org/10.3390/coatings12081204 - 17 Aug 2022
Cited by 1 | Viewed by 1879
Abstract
The current research explored the integrative effect of antimicrobial edible films and modified atmosphere packaging (MAP) on the quality parameters and shelf-life of bottle gourd burfi, which is a heat-desiccated composite Indian confection. The edible antimicrobial films prepared using a combination of nisin [...] Read more.
The current research explored the integrative effect of antimicrobial edible films and modified atmosphere packaging (MAP) on the quality parameters and shelf-life of bottle gourd burfi, which is a heat-desiccated composite Indian confection. The edible antimicrobial films prepared using a combination of nisin and natamycin (NANIF) were evaluated for their antimicrobial activity as the first line of defense against Bacillus cereus and Aspergillus niger. The product was wrapped in developed films, which was followed by flushing of the altered environment employing MAP in a closed PP box and evaluation during refrigerated storage at 4 ± 2 °C, comparing the product with the control counterpart. During this period, the physicochemical, sensory, and microbiological status of the product was assessed. Results indicated a significant (p ≤ 0.05) variance between the two kinds of samples wherein the antimicrobial film produced excellent results in terms of being less supportive toward microbial growth, thereby extending the life of film-treated samples beyond 35 days compared to the control (21 days). In addition, the product conformed to the legal standards of microbiological count well under the permissible limits laid by the FSSAI. Furthermore, the sensory characteristics of the product did not change much, illustrating the significance of the integrative approach. Full article
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14 pages, 2992 KiB  
Article
Machining of Carbon Steel under Aqueous Environment: Investigations into Some Performance Measures
by Mushtaq Ali, Tahir Abdul Hussain Ratlamwala, Ghulam Hussain, Tauheed Shehbaz, Riaz Muhammad, Muhammad Aamir, Khaled Giasin and Danil Yurievich Pimenov
Coatings 2022, 12(8), 1203; https://doi.org/10.3390/coatings12081203 - 17 Aug 2022
Viewed by 1534
Abstract
In this study, a new machining approach (aqueous machining) is applied for mill machining and its performance is compared with traditional wet machining. AISI 1020 steel is employed as the test material and Taguchi statistical methodology is implemented to analyze and compare the [...] Read more.
In this study, a new machining approach (aqueous machining) is applied for mill machining and its performance is compared with traditional wet machining. AISI 1020 steel is employed as the test material and Taguchi statistical methodology is implemented to analyze and compare the performance of the two machining approaches. The cutting speed, feed rate, and depth of cut were the machining parameters used for both types of machining, while the selected response variables were surface roughness and hardness. Temperature variations were also recorded in aqueous machining. Compared with wet machining, aqueous machining resulted in lower surface roughness (up to 13%) for the same operating conditions and about 14% to 16% enhancement in hardness due to the formation of finer pearlite, as revealed by the microstructure analysis. Compared to the parent unmachined surface, the hardness of machined surfaces was 24% to 31% higher in wet machining and 44% to 51% higher in aqueous machining. Another benefit of aqueous machining was the energy gain, which ranged from 718 to 8615.96 J. This amount of heat energy can be used as waste heat for preheating domestic hot water, running the organic Rankine cycle with waste heat and preheating the inlet saline water for desalination, vacuum desalination, etc. If successfully implemented in the future, this idea will provide a step towards achieving sustainable machining by saving lubricants and toxic wastes in addition to saving energy for secondary applications. Full article
(This article belongs to the Special Issue Recent Advances in the Machining of Metals and Composites)
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18 pages, 1646 KiB  
Review
Can Graphene Oxide Help to Prevent Peri-Implantitis in the Case of Metallic Implants?
by Radu Nartita, Mihai Andrei, Daniela Ionita, Andreea Cristiana Didilescu and Ioana Demetrescu
Coatings 2022, 12(8), 1202; https://doi.org/10.3390/coatings12081202 - 17 Aug 2022
Cited by 4 | Viewed by 2143
Abstract
This paper is a review focused on the capability of graphene oxide (GO) coatings in preventing peri-implantitis. Firstly, the paper establishes GO’s place in the frame of carbonic materials and its role as a composite material in dentistry in the prevention of bacterial [...] Read more.
This paper is a review focused on the capability of graphene oxide (GO) coatings in preventing peri-implantitis. Firstly, the paper establishes GO’s place in the frame of carbonic materials and its role as a composite material in dentistry in the prevention of bacterial infections and in sustaining osseointegration. Secondly, the most relevant articles on GO as implant coatings and their associated shortcomings are presented and emphasizing is placed on the areas where more data is needed. The main chapters are devoted to the relationship between GO and biofilm formation on the implants and the surrounding periodontal tissue and we also attempt to evaluate GO’s efficacy in the case of peri-implantitis. Our findings strongly indicate that GO is a promising material for mitigating the problems mentioned, but some answers remain to be answered through rigorous research before declaring it a real success. Full article
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10 pages, 2372 KiB  
Article
Novel Terahertz Properties of Nanostructured Mn3+0.53Sn Films with Different Crystalline Orientations Driven by Ostwald Ripening on (0001) c-Al2O3
by Shaopeng Yang, Xinyue Wang, Qiujin Wang, Tong Xu, Qian Wang, Jin Guo, Jian Zuo, Cunlin Zhang, Wen Xu, Yujun Song, Ying Liu, Jing Wang and Hai Wang
Coatings 2022, 12(8), 1201; https://doi.org/10.3390/coatings12081201 - 17 Aug 2022
Viewed by 1644
Abstract
The characteristic energies of elementary excitations and collective modes in many quantum materials lie mostly in the terahertz (THz) frequency range, which provides a wide space for the development of THz optical materials and devices. In particular, topological Weyl semimetal Mn3Sn [...] Read more.
The characteristic energies of elementary excitations and collective modes in many quantum materials lie mostly in the terahertz (THz) frequency range, which provides a wide space for the development of THz optical materials and devices. In particular, topological Weyl semimetal Mn3Sn is a noncollinear antiferromagnet with anomalous THz properties, which is strongly affected by thermal energy and external magnetic fields. Despite the explosive growth of the research on magnetic Weyl semimetals recently, its nanoscale structure for applications in THz optical devices remains to be explored. Here, we fabricated nanostructured Mn3+0.53Sn films with different crystal orientations, driven by Ostwald Ripening (OR) on (0001) c-Al2O3. A huge anisotropic THz response manifested a firm link between the optical properties of Weyl antiferromagnet Mn3Sn and its contrivable spin structures. The topological properties of Mn3Sn are robustly protected in its nanostructures. This work can provide a new horizon for the fabrication of a nanostructured magnetic Weyl alloy and for its potential applications in subwavelength high-performance THz devices. Full article
(This article belongs to the Section Thin Films)
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14 pages, 2377 KiB  
Article
Evaluation Test of NO Degradation by Nano-TiO2 Coatings on Road Pavements under Natural Light
by Mingjing Fang, Longfan Peng, Yunyu Li, Yuxiao Cheng and Lu Zhan
Coatings 2022, 12(8), 1200; https://doi.org/10.3390/coatings12081200 - 17 Aug 2022
Cited by 1 | Viewed by 1850
Abstract
Reducing or degrading nitrogen oxides (NOx) emitted by automobile exhausts has diversified ways. This paper presents a solution to degrade NO by Nano-sized titanium dioxide (Nano-TiO2) mixed with coating materials for traffic marking on road pavements. The effect on [...] Read more.
Reducing or degrading nitrogen oxides (NOx) emitted by automobile exhausts has diversified ways. This paper presents a solution to degrade NO by Nano-sized titanium dioxide (Nano-TiO2) mixed with coating materials for traffic marking on road pavements. The effect on degradation was evaluated by adopting a simple laboratory test with statistical analysis. During the test, five different contents of Nano-TiO2, 2%, 3%, 4%, 5%, and 6%, mix with a coating material for pavement marking, followed by an interpretation of the micro mechanism of degradation effect. The results show that the pavement marking coatings mixed with Nano-TiO2 has a good performance on NO degradation. The effect of degradation is increased with increasing the content of Nano-TiO2 particles, however. At the same time, a peak value with about 70% of the maximum removing rate existed when applying 4% Nano-TiO2 due to the agglomeration phenomenon for nanoparticles close to each other for adding more Nano-TiO2. The methods to reduce agglomeration are also suggested, and a routine field test for all potential traffic coating materials is recommended in this study. Full article
(This article belongs to the Special Issue Functional Materials for Building and Pavement Coatings)
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