Surfaces Of Various Materials Research Articles

Autoencoder-based anomaly detection for surface defect inspection

In this paper, the unsupervised autoencoder learning for automated defect detection in manufacturing is evaluated, where only the defect-free samples are required for the model training. The loss function of a Convolutional Autoencoder (CAE) model only aims at minimizing the reconstruction errors, and makes the representative features widely spread. The proposed CAE in this study incorporates a regularization that improves the feature distribution of defect-free samples within a tight range. It makes the representative feature vectors of all training samples as close as possible to the mean feature vector so that a defect sample in the evaluation stage can generate a distinct distance from the trained center of defect-free samples. The proposed CAE model with regularizations has been tested on a variety of material surfaces, including textural and patterned surfaces in images. The experimental results reveal that the proposed CAE with regularizations significantly outperforms the conventional CAE for defect detection applications in the industry.

Polymers with antiviral properties: A brief review.

Viruses that are pathogenic to humans and livestock pose a serious epidemiological threat and challenge the world's population. The SARS-CoV-2/COVID-19 pandemic has made the world aware of the scale of the threat. The surfaces of various materials can be a source of viruses that remain temporarily contagious in the environment. Few polymers have antiviral effects that reduce infectivity or the presence of a virus in the human environment. Some of the effects are due to certain physical properties, e.g., high hydrophobicity. Other materials owe their antiviral activity to a modified physicochemical structure favoring the action on specific virus receptors or on their biochemistry. Current research areas include: gluten, polyvinylidene fluoride, polyimide, polylactic acid, graphene oxide, and polyurethane bound to copper oxide. The future belongs to multi-component mixtures or very thin multilayer systems. The rational direction of research work is the search for materials with a balanced specificity in relation to the most dangerous viruses and universality in relation to other viruses.

A quantitative method to assess bacterial adhesion using recombinant bioluminescent Pseudomonas aeruginosa.

Bioluminescence technology has been widely used in the field of medical detection. The bioluminescent lux reporter system provides a non-invasive platform to monitor bacterial growth and expression in real time. This study aimed to establish a method for detecting bacterial adhesion on the surface of materials, including medical devices, by using recombinant bioluminescent Pseudomonas aeruginosa containing a lux reporter. By monitoring the growth and bioluminescent properties of the recombinant PAO1-lux strain, the optimal test conditions for bacterial adhesion detection in vitro were determined to be as follows: an initial inoculation density of 105 to 106 CFU/mL, M9 medium at a pH 6.2, an adhesion time of 6 h, and the collection of adherent bacteria by ultrasonic cleaning. The traditional CFU counting method and the bioluminescence method were compared, and the applicability of the new method was verified by testing the adhesion of bacteria on the surface of various materials. The validated bioluminescent strains could serve as strong candidates to be used as bacterial detection tools in applications such as bacterial adhesion evaluation as well as supplements and alternatives to traditional microbiological testing procedures. In addition, this method has the potential to enable the study of bacterial adhesion on the surface of inanimate objects and living tissues. With the development of this method and its wide applicability, it is expected to become a standard method for the detection of bacterial adhesion and the screening of anti-adhesion materials.

A mussel-inspired delivery system for enhancing self-healing property of epoxy coatings

Dopamine (DA), one type of mussel-inspired biological molecules with adhesive nature and corrosion inhibitor property, are often used to functionalize the surfaces of various materials. Herein, we report the application of polydopamine (PDA) microcapsules as novel nanocontainers for the purpose, loading corrosion inhibitor (benzotriazole) in its shell structure, and then were embedded into epoxy coatings to provide self-healing and anti-corrosion protection for carbon steel. Fast release of benzotriazole in acidic environment caused by local corrosion and the chelating effect of PDA-Fe3+ can synergistically promote the formation of protective film on bare steel surface, which endows coatings with self-healing functionality. Electrochemical impedance spectroscopy (EIS), local electrochemical impedance spectroscopy (LEIS), and spray tests were conducted to evaluate the active inhibition and corrosion resistance of the loaded coatings. The scratched coating with incorporation of nanocontainers presented better protection performance, exhibiting increased Ro (oxide layer resistance) and Rct (charge transfer resistance) during initial immersion periods. The EIS tests in long-term immersion were also performed to confirm the anti-corrosion effect of composited coatings. These results demonstrated that benzotriazole-decorated PDA capsules dramatically enhanced the self-healing properties and anti-corrosion performance of epoxy coatings with the synergistic help of PDA and benzotriazole.

Microorganisms and cationic surfactants

Quaternary ammonium salts (QAS) as cationic surfactants with an amphiphilic structure show biocidal activity against non-pathogenic and pathogenic microorganisms (Gram-positive, Gram-negative bacteria, fungi, as well as lipophilic viruses) occurring in planktonic form or forming biofilms. They can also coat the surface of various materials (glass, metal, silicone, polyester) from which medical devices are made, such as: catheters, implants, heart valves, endoprostheses, and this allows inhibiting the adhesion of microorganisms to these surfaces. In their chemical structure, these surfactants contain labile bonds, e.g. ester or amide bonds, which enable the biodegradation of the compounds. Thanks to this, they are classified as “green chemistry”. Their biological activity depends on the length of the hydrophobic chain and the structure of the hydrophilic head of the compound. QAS have an affinity for the cell membrane by interacting with its lipids and proteins, which can lead to its disintegration. They have the ability to inhibit the activity of H+-ATPase of the cell membrane, the enzyme responsible for its electrochemical gradient and the transport of nutrients to the cell, e.g. amino acids. These compounds can influence the lipid composition (quantitative and qualitative) of the cell membrane of microorganisms. They are also inhibitors of respiratory processes and can induce the formation of reactive oxygen species. These surfactants are capable of forming micelles and liposomes in an aqueous environment. They are widely used in medicine (as disinfectants, DNA carriers in gene therapy), in industry and environmental protection (as biocides, preservatives) and in agriculture (as fungicides). The widespread use of QAS in many fields causes the growing resistance of microorganisms to these compounds. A common mechanism that generates reduced susceptibility to QAS is the presence of efflux pumps.

Treatment of wood with atmospheric plasma discharge: study of the treatment process, dynamic wettability and interactions with a waterborne coating

Abstract Plasma treatment is becoming a mature technique for modification of surfaces of various materials, including wood. A better insight in the treatment process and the impact of the plasma on properties of wood bulk are still needed. The study was performed on Norway spruce and common beech wood, as well as their thermally modified variations. The formations of the airborne discharge, as well as mass changes of the treated wood, were monitored. The impact of such treatment on wood-coating interaction was investigated by evaluating the dynamic wettability and penetration into wood. At the wood surface, plasma streamers were observed more intense on denser latewood regions. Wood mass loss was higher with increasing number of passes through the plasma discharge and was lower for thermally modified wood than for unmodified wood. Plasma treatment increased the surface free energy of all wood species and lowered the contact angles of a waterborne coating, these together indicating enhanced wettability after treatment. Finally, the distribution and penetration depth of the coating were studied with X-ray microtomography. It was found that the coating penetrated deeper into beech than into spruce wood. However, the treatment with plasma increased the penetration of the coating only into spruce wood.

Plasma source of charged particles for the formation of combined ion-electron beams

One of the ways to increase the efficiency of the implementation of ion-plasma technologies of exposure to the surfaces of various materials is partial or full compensation of the positive charge of ions in the stream or on the treated surface, for which additional emitting systems are used that create compensating electron flows in the discharge space, accelerating gap or on the processed surface. It was previously shown that for the implementation of such a compensating effect, it is possible to use plasma sources of charged particles, capable of forming beams of both signs when the polarity of the accelerating voltage is changed. The main problem in this case is the difficulty in achieving simultaneously high emission efficiency of ions and electrons, since the conditions for their emission from plasma are significantly different. This article proposes a concept and a design developed on its basis for a prototype of a multi-discharge plasma electron-ion source for the joint or alternating formation of electron and ion beams. It is shown that the proposed design realizes the possibility of increasing the perveance by compensating for the space charge by particles of the opposite sign. A number of characteristics of the developed model of a plasma electron-ion source (current-voltage characteristics of the extraction of electrons and ions) are presented and its prospects for further development of an electron-ion source for industrial use on its basis are shown. Combined or alternating ion-electron beams formed in the presented source can be used to implement the technology of applying thin-film layers of metals, semiconductors, and dielectrics to maintain ionization processes and ensure stable discharge burning, compensation of both the space charge in the beam and the surface charge on the formed film.

Metal Complex Bactericides with Detergent Properties

This communication describes the possibility of developing new metal complex bactericides with detergent properties that have no analogues. They irreversibly suppress bacteriophages, intestinal bacteria, virions, cocci, salmonella, trichomonas, and Becreus spores in fat-containing contaminants on the surfaces of various materials, in combination with washout of contaminants. In doses lethal to pathogens, the bactericide is safe for microflora, animals, and humans. The results seem to be relevant to the case of COVID-19 and possible worsening of the epidemiological situation.

Dynamic Simulation Test of Chemical Cleaning of Superheater

The dissolution of superheater oxide skin by compound cleaning agent was studied in a dynamic simulation test device. The corrosion rate of compound cleaning agent on various materials was studied by weight loss method. The results show that the compound cleaning agent can remove the oxide skin formed on the surface of various materials and the austenitic steel was cleaned without intergranular corrosion.

Q-switched mode in laser ceramics with Cr4+ for technological surface cleaning

A compact solid-state laser based on a Nd:YAG (1 at. %) ceramic active media in the Q-switched mode was studied. Ceramic YAG elements with different concentrations (0.1 to 1 at.%) of Cr4+ doping were used as a Q-switches, 50 to 500 ns pulses were registered with the high energy single pulse. Transparent ceramic obtained by thermosetting sintering. A laser scheme is proposed with a pulse duration and energy setting that contains a composite element for combining the properties of the studied samples of transparent ceramics in one volume. This scheme allows you to implement a compact laser to clean the surface of various materials (glass, concrete, plastic, steel, etc.) from contamination.

Optimization and experiment of key components in pneumatic peanut pod conveyor

Research interest in pneumatic conveying technologies in processes such as peanut harvesting and shelling has grown rapidly in recent years. However, the use of pneumatic conveyors in this application suffers from high pod damage rates and duct obstruction. To address these issues, we analyzed the critical speed of pneumatic transport for conveying the peanut pods and measured the angle of friction and coefficient of restitution of peanut pods on a variety of material surfaces. Based on the results of these tests, optimizations and improvements were made to the separator bowl, air supply duct, and conveying duct. A pneumatic conveying experiment was then performed using peanut pods. In the factorial experiment, it was found that increases in fan speed increase the pod damage rate and transport efficiency, while increases in the thickness of the cushioning/anti-obstruction layer decrease the rate of pod damage and transport efficiency. Pod damage rates were significantly affected by fan speed, the thickness of the cushioning/obstruction prevention layer, and interaction between these factors, while transport efficiency was only significantly affected by fan speed. It is proved by the machine verification test, the optimal parameters for the pneumatic transport of Baisha peanut pods with a moisture content of 7.24% was a fan speed of 2700 r/min and a cushioning/anti-obstruction layer thickness of 6 mm. A pod damage rate of 5.19% and transport efficiency of 92.03% were achieved using these parameters, which are sufficient for meeting the requirements of industrial applications. Keywords: pneumatic transport, material properties, peanut pods, damage rate, transport efficiency DOI: 10.25165/j.ijabe.20201303.4609 Citation: Gao X M, Xie H X, Gu F W, Wei H, Liu M J, Yan J C, et al. Optimization and experiment of key components in pneumatic peanut pod conveyor. Int J Agric & Biol Eng, 2020; 13(3): 100–107.

Synthesis of Polypyrrole/V2O5 Composite Film on the Surface of Magnesium Using a Mild Vapor Phase Polymerization (VPP) Method for Corrosion Resistance

The vapor phase polymerization (VPP) method is a conventional strategy for synthesizing conducting polymers (CPs) on the surfaces of various materials. However, the current VPP method performed on a metal surface usually requires harsh reaction conditions, such as high temperature and low vacuum. In this paper, a polypyrrole (PPy) and vanadium pentoxide (V2O5) composite film was synthesized on the surface of Mg using a mild VPP method. Here, V2O5 was used as an oxidant, and it was found that the oxidation of pyrrole (Py) vapor on the surface of V2O5, which had been previously coated on the surface of Mg, could be performed at room temperature under normal atmospheric pressure. The formation of the PPy/V2O5 composite was verified by Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX) spectroscopy. A thermogravimetric analyzer (TGA) was used to study the thermal stability of the composite. Subsequent corrosion tests showed that the PPy/V2O5 composite film could slow down the corrosion of Mg in 3.5 wt% NaCl. It is expected that the mild VPP method may find great potential in the fields of synthesis of CPs and the corrosion protection of reactive metals.

Efficiency improvement of solar stills through wettability alteration of the condensation surface: An experimental study

The condensation process is of great importance in many heat transfer devices in which a large amount of energy must be transferred. Furthermore, condensation is a crucial part of energy conversion and affects the energy efficiency of thermal desalination plants and solar stills. During the condensation process in solar stills, an essential part of the energy is transferred through the condensation surface to produce fresh water. Therefore, the condensation surface plays a significant role in the working efficiency of solar stills. The wettability of the condensation surface influences the condensation mechanism, which, in turn, affects the efficiency of solar stills. This study aims to improve the efficiency of solar stills through wettability alteration of the condensation surface by utilizing nanoparticles. To this end, the condensation surfaces of various materials were selected and coated with titanium dioxide and silicon nanoparticles (which have different wetting properties) to increase and/or decrease the surface wettability. Outdoor and indoor experiments were conducted to evaluate the productivity of solar stills with regard to utilizing clean and nano-coated condensation surfaces. Furthermore, scanning electron microscopy and atomic force microscopy analyses were utilized to examine the deposition of nanoparticles on the condensation surfaces. The experimental results indicated that nano-coated condensation surfaces significantly improved the efficiency of solar stills. For instance, silicone coating caused an increase in the productivity of solar still by 20% for the glass condensation cover.

Shape and Reflectance Reconstruction Using Concentric Multi-Spectral Light Field.

Recovering the shape and reflectance of non-Lambertian surfaces remains a challenging problem in computer vision since the view-dependent appearance invalidates traditional photo-consistency constraint. In this paper, we introduce a novel concentric multi-spectral light field (CMSLF) design that is able to recover the shape and reflectance of surfaces of various materials in one shot. Our CMSLF system consists of an array of cameras arranged on concentric circles where each ring captures a specific spectrum. Coupled with a multi-spectral ring light, we are able to sample viewpoint and lighting variations in a single shot via spectral multiplexing. We further show that our concentric camera and light source setting results in a unique single-peak pattern in specularity variations across viewpoints. This property enables robust depth estimation for specular points. To estimate depth and multi-spectral reflectance map, we formulate a physics-based reflectance model for the CMSLF under the surface camera (S-Cam) representation. Extensive synthetic and real experiments show that our method outperforms the state-of-the-art shape reconstruction methods, especially for non-Lambertian surfaces.

Enabling highly effective underwater oxygen-consuming reaction at solid-liquid-air triphasic interface

Electrode surfaces with superhydrophobic and conductive properties exhibit a unique energy-mass transfer behavior in electrolytes. Therefore, the rational design of electrode surface structures, conductivity, and infiltration performance is expected to yield more efficient electrochemical reactions and solve the gas-deficit problem that hinders many underwater gas-consuming reaction systems. In this paper, hydrogenated carbon nano-onions displaying superhydrophobicity and conductivity were prepared by microwave plasma-enhanced chemical vapor deposition, which exhibited remarkable transferability and designability. The fabricated carbon nano-onions were used to modify the surfaces of various materials and structures toward their application to self-cleaning, oil-water separation, and enabling highly effective underwater oxygen-consuming reactions. Systematic analyses of the different wetting states of the superhydrophobic electrodes coated with the fabricated carbon nano-onions indicated that the different wetting states have important effects on their behaviors for underwater nucleation reactions, thus changing the efficiency of underwater oxygen-consuming reaction systems. The results reveal that designing a superhydrophobic electrode with a Wenzel-Cassie coexistent underwater wetting state, rather than a Cassie state or Wenzel state, is the key to enabling highly effective underwater oxygen-consuming reactions.

Optimization and experiment of key components in pneumatic peanut pod conveyor

Research interest in pneumatic conveying technologies in processes such as peanut harvesting and shelling has grown rapidly in recent years. However, the use of pneumatic conveyors in this application suffers from high pod damage rates and duct obstruction. To address these issues, we analyzed the critical speed of pneumatic transport for conveying the peanut pods and measured the angle of friction and coefficient of restitution of peanut pods on a variety of material surfaces. Based on the results of these tests, optimizations and improvements were made to the separator bowl, air supply duct, and conveying duct. A pneumatic conveying experiment was then performed using peanut pods. In the factorial experiment, it was found that increases in fan speed increase the pod damage rate and transport efficiency, while increases in the thickness of the cushioning/anti-obstruction layer decrease the rate of pod damage and transport efficiency. Pod damage rates were significantly affected by fan speed, the thickness of the cushioning/obstruction prevention layer, and interaction between these factors, while transport efficiency was only significantly affected by fan speed. It is proved by the machine verification test, the optimal parameters for the pneumatic transport of Baisha peanut pods with a moisture content of 7.24% was a fan speed of 2700 r/min and a cushioning/anti-obstruction layer thickness of 6 mm. A pod damage rate of 5.19% and transport efficiency of 92.03% were achieved using these parameters, which are sufficient for meeting the requirements of industrial applications. Keywords: pneumatic transport, material properties, peanut pods, damage rate, transport efficiency DOI: 10.25165/j.ijabe.20201303.4609 Citation: Gao X M, Xie H X, Gu F W, Wei H, Liu M J, Yan J C, et al. Optimization and experiment of key components in pneumatic peanut pod conveyor. Int J Agric & Biol Eng, 2020; 13(3): 100–107.

A Hybrid Character Recognition Approach Using Fuzzy Logic and Stroke Bayesian Program Learning With Naïve Bayes in Industrial Environments

Automated character recognition is critical for reading and tracking data in a variety of fields. It is particularly challenging in industrial settings since information may be printed on the surface of various materials with complex and uneven shapes, causing overlapping, obstructing, and distorting characters. We propose a hybrid character recognition approach using fuzzy logic and stroke Bayesian program learning with naive Bayes. During character segmentation, touching characters are separated using support vector machines and a three-feature fuzzy segmentation strategy that uses particle swarm optimization. This approach includes a new methodology for stroke presentation and extraction using a prebuilt primitive-stroke library containing prior knowledge. During character recognition, a conceptual character model is constructed using stroke Bayesian program learning. Monte Carlo Markov chain sampling is used to produce a fitting model for each character. This model predicts character classification by calculating the probability that a target sample belongs to a training set. To this end, naive Bayes effectively discerns extremely similar characters. We evaluate our method experimentally using a database of industrial images and the NIST dataset. Our method outperforms existing state-of-the art methods.

Ar-Driven Gas Discharge System Based on Dielectric Zeolite Material

A progress update on the development of microporous dielectric materials for gas discharge systems, microelectronics, and energy storage devices is described herein. Experimental results on the dependence of the discharge emission intensity (DEI) on the current in ambient air and argon media for various values of the gas discharge gap dg (45–250 μm) and residual pressure pg (5.33–101 kPa) in a gas discharge system with a dielectric zeolite electrode (ZGDS) are presented for the first time. The unique electronic properties of the microporous surface of the zeolite used in the ZGDS could significantly enhance the emission of electrons from its surface, thereby reducing the ignition voltage Uign. The ignition voltage Uign and the DEI of the ZGDS are found to depend significantly on the electrooptical parameters of the microporous zeolite as well as dg, pg, and the gaseous medium. We therefore believe that a ZGDS with a dielectric microporous zeolite electrode is very promising as a source of cold nonequilibrium plasma at atmospheric pressure (AP) and could be used to create plasma-chemical sources that activate the gaseous medium and surfaces of various materials at AP.

Studies of Morphology and Size of Calcium Carbonate Crystals Nucleating on Surfaces of Various Materials

The effects of material surface characteristics on the morphology and size of calcium carbonate crystals nucleating under cold wall pipe flow conditions were studied. We found that high surface energy materials could accelerate the conversion of crystals from vaterite to calcite, and the crystal size increased. Aragonite was found to be absent throughout the experiment. The deposition of calcium carbonate crystals is a layer-over-layer formation process. In the initial deposition period, the crystals are large and continue to grow until covering the material surface. At subsequent stages, the crystals forming on the existing fouling become much smaller. Studying the influence of material surface on the morphology and size of calcium carbonate crystals is important both for the reasonable selection of industrial materials and for the synthesis of calcium carbonate crystals with certain morphology and size.

Modeling of dry snow adhesion during normal impact with surfaces

Contamination due to dry snow smoke adhesion is an evident danger for sensor blinding on future autonomous driving cars under winter road conditions. This paper examines at what velocities ice particles and agglomerates, representing dry snow, adhere to surfaces of various materials. Contact models for normal direction, tangential sliding, and tangential rolling that account for the adhesive interaction of spherical particles due to Van der Waals forces are used in the study. Three different scenarios of impacts are presented i) single particle impact, ii) small agglomerate impacts, and iii) large agglomerate impacts. It is shown that by increasing the number of particles in an agglomerate, the velocity at which the agglomerate sticks to the impact wall increases, i.e. the agglomerate is more likely to stick to a surface. It is also shown how material properties influence the tendency of dry road snow to adhere to a surface.