Photocatalytic Degradation of Oxytetracycline in Aqueous Solutions with TiO2 in Suspension and Prediction by Artificial Neural Networks

In this study, the photocatalytic degradation of oxytetracycline (OTC) in aqueous solutions has been studied under different conditions such as initial pollutant concentrations, amount of catalyst, and pH of the solution. Experimental results showed that photocatalysis was clearly the predominant process in the pollutant degradation, since OTC adsorption on the catalyst and photolysis are negligible. The optimal TiO₂ concentration for OTC degradation was found to be 1.0 g/L. The apparent rate constant decreased, and the initial degradation rate increased with increasing initial OTC concentration with the other parameters kept unchanged. Subsequently, data obtained from photocatalytic degradation were used for training the artificial neural networks (ANN). The Levenberg–Marquardt algorithm, log sigmoid function in the hidden layer, and the linear activation function in the output layer were used. The optimized ANN structure was four neurons at the input layer, eighteen neurons at the hidden layer, and one neuron at the output layer. The application of 18 hidden neurons allowed to obtain the best values for R² and the mean squared error, 0.99751 and 7.504e–04, respectively, showing the relevance of the training, and hence the network can be used for final prediction of photocatalytic degradation of OTC with suspended TiO₂.     

Predicting chain dimensions from an artificial neural network model

Artificial neural network models are used to investigate polymer chain dimensions. In our model, the input nodes are glass transition temperature (T_g), entanglement molecular weight (M_e), and melt density (ρ). The number of nodes in the hidden layer is eight. We found that the relative error for prediction of the characteristic ratio ranges from 0.77 to 7.5% and that the overall average error is 3.57%. Artificial neural network models may provide a new method for studying statistics properties of polymer chains. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3163–3167, 2000     

Anti-Reflective Coatings for CRTs by Sol-Gel Process

Two types of anti-reflective coatings composed of nano-particles were developed for cathode ray tubes (CRTs). The anti-reflective and anti-static coating is composed of two layers. An outer SiO₂ layer is formed over a porous inner layer composed of titanium oxynitride (TiO _x N_y), antimony-doped tin oxide (ATO) and SiO₂. To control the reflection of the film, a porous structure is formed using a mixed sol composed of TiO _x N _y -ATO particles and hydrolyzed-polymerized tetraethoxy-silane (TEOS). The resulting double layered coating is shown to consist in a nanocomposite pseudo three-layer structure. The antireflective electromagnetic-wave-shielding coating is also composed of two layers. An outer SiO₂ layer is formed over an electric-conductive inner layer composed of silver colloids, TiO _x N _y nano particles. Silver colloids are used to obtain a film having low surface resistivity and TiO _x N _y nano-particles contained in the inner layer enhance the durability of the film. To reduce the plasma-resonance absorption caused by silver colloids, silver ions are added to the outer layer solution. The silver ions diffuse into the inner layer from the outer layer when the film is cured, touch to the surface of silver colloids, suppress the silver colloid growth and reduce the specific absorption of the film. These coatings are successfully applied to the panel glass for CRTs on an industrial scale.     

Sol-enhanced triple-layered Ni–P–TiO2 composite coatings

A novel coating process, TiO₂ sol enhanced Ni–P electroless composite coatings on carbon steel, is presented in this paper. Transparent TiO₂ sol was added into the electroless plating Ni–P solution at a controlled rate, leading to in situ synthesis of a triple-layered Ni–P–TiO₂ composite coating, i.e. the inner, transition and outer layers. The inner layer has a thickness of ~3 μm, mainly composed of Ni and P elements. The transition layer of the coating has a relatively high content of TiO₂ with a thickness of ~500 nm and a columnar-structure. The thickness of the outer layer was ~7 μm, with almost evenly distributed Ni, P and TiO₂. The hardness and Young’s modulus of the composite coating were greatly improved to ~10 and ~200 GPa, respectively, compared to ~6 and ~110 GPa of the traditional Ni–P coating.     

Artificial Neural Network and Fuzzy Clustering – New Tools for Evaluation of Depth Profile Data?

 Depth profiling has been performed by using Auger electron spectrometry (AES) and X-ray photoelectron spectrometry (XPS) in combination with Ar-ion sputtering. The data obtained by both surface-analytical methods have been evaluated by means of factor analysis and afterwards by applying an artificial neural network or fuzzy clustering in order to determine the compositional layering of different samples such as a Cr₂O₃/CrN sandwich layer, tarnish layers on a nickel based alloy and on steel, and the coating of a Si₃N₄ ceramic powder. The applied artificial neural network was a Kohonen network. It turned out that the method of fuzzy c-means clustering was more successful than Kohonen network due to the fact that fuzzy c-means clustering starts with more input information which can be obtained from factor analysis.     

Use of an Electronic Tongue Based on All‐Solid‐State Potentiometric Sensors for the Quantitation of Alkaline Ions

An array of eight nonspecific potentiometric sensors was used in combination with multivariate calibration for the simultaneous determination of NH , K⁺ and Na⁺ ions. The sensors were of the all‐solid‐state type and employed a PVC polymer membrane. Signals were processed by using a multilayer artificial neural network (ANN). The ANN configuration used was optimized by using 8 neurons in the input layer, 5 in the hidden layer and 3 in the output layer. Use of the Bayesian Regularization algorithm allowed a quick building of an accurate model, as confirmed by random multi‐starting of network weights. The system was used to analyze synthetic and river water, waste water and fertilizer samples. Correct results were obtained for the three ions in synthetic and real water samples; in fertilizers, ammonium ion can be determined, while sodium and potassium show biased results.     

Corrosion behavior of tantalum alloying on γ‐TiAl by double‐glow plasma surface metallurgy technique

The Ta coating with corrosion resistance is grown on the γ‐TiAl substrate by double‐glow plasma surface metallurgy technique, followed by the electrochemical test in 10 wt%, 20 wt% HCl and 10 wt%, 40 wt% H₂SO₄ solution. The data of nanohardness and elastic modulus are collected by the nanoindention test. The adhesion strength of Ta coating is investigated by means of the scratch test. The study of corrosion resistance is performed using potentiodynamic polarization and electrochemical impedance spectroscopy and measured by SEM and X‐ray diffraction. Results highlight that the Ta coating is tightly bonded to the γ‐TiAl substrate, consisting of the deposition layer and diffusion layer. Experimental data indicate that the Ta coating presents excellent corrosion resistance, which is confirmed by the high values of polarization resistance (R_p) and the low values of corrosion current density (i_corr). The surface nanohardness of the Ta coating is improved from 3.41 to 7.29 GPa, nearly twice of that of the substrate. The Ta₂O₅ formed on the coating is able to hold back the penetration of adverse ions inwardly, owing to its dense structure and adhesion effect. Copyright © 2017 John Wiley & Sons, Ltd.     

Reflective and conductive surface‐silvered polyimide films prepared by surface graft copolymerization and electroless plating

Argon plasma‐pretreated polyimide (PI) films were subjected to UV‐induced surface graft copolymerization with 4‐vinylpyridine(4VP) under atmospheric conditions. Electroless plating of silver was carried out effectively on the 4VP graft copolymerized PI (PI‐g‐P4VP) surface after PdCl₂ activation and in the absence of SnCl₂ sensitization (the Sn‐free process). The surface compositions of the modified PI films were studied by X‐ray photoelectron spectroscopy (XPS). XPS results showed that the PI‐g‐P4VP surface is ready for electroless deposition of silver via the Sn‐free process. The grafted 4VP layer with well‐preserved pyridine groups was used not only as the chemisorption sites for the palladium complexes (without the need for prior sensitization by SnCl₂) during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The silver metallized PI films show high reflectivity and conductivity with a surface resistance of 1.5 Ω and a reflectivity of 91.3%, respectively. Copyright © 2007 John Wiley & Sons, Ltd.     

Development and characterization of transparent waterborne polyurethane acrylate/fullerenols thin-film nanocomposite as thermal-insulating coating

Thermal-insulating coating can lower the energy consumption and cooling costs, which caters to the tendency of environmental protection and energy conservation. Transparent waterborne polyurethane acrylate thin-film nanocomposite was developed by incorporating the fullerenol C₆₀(OH)₁₂(ONa)₂ into the system using ultrasonic dispersion. The thin-film nanocomposite was then synthesized by ultraviolet radiation curing and chemical crosslinking, and its morphology and chemical structures were characterized. Thermogravimetric analysis and differential thermal gravity were used to evaluate the thermal stability. The surface and mechanical properties were tested by the pendulum hardness and MEK resistance. The optical and thermal-insulating properties were assessed by the ultravioletvisible-near infrared spectrophotometer and indoor environmental simulation experiment. The thermal-insulating measurements showed that the glass coated thin-film nanocomposite possessed better thermal-insulation effect than empty glass.     

An electronic tongue using potentiometric all-solid-state PVC-membrane sensors for the simultaneous quantification of ammonium and potassium ions in water

The simultaneous determination of NH₄⁺ and K⁺ in solution has been attempted using a potentiometric sensor array and multivariate calibration. The sensors used are rather non-specific and of all-solid-state type, employing polymeric (PVC) membranes. The subsequent data processing is based on the use of a multilayer artificial neural network (ANN). This approach is given the name "electronic tongue" because it mimics the sense of taste in animals. The sensors incorporate, as recognition elements, neutral carriers belonging to the family of the ionophoric antibiotics. In this work the ANN type is optimized by studying its topology, the training algorithm, and the transfer functions. Also, different pretreatments of the starting data are evaluated. The chosen ANN is formed by 8 input neurons, 20 neurons in the hidden layer and 2 neurons in the output layer. The transfer function selected for the hidden layer was sigmoidal and linear for the output layer. It is also recommended to scale the starting data before training. A correct fit for the test data set is obtained when it is trained with the Bayesian regularization algorithm. The viability for the determination of ammonium and potassium ions in synthetic samples was evaluated; cumulative prediction errors of approximately 1% (relative values) were obtained. These results were comparable with those obtained with a generalized regression ANN as a reference algorithm. In a final application, results close to the expected values were obtained for the two considered ions, with concentrations between 0 and 40 mmol L^–1.     

Bisphosphoric modified amino functional [xFe3O4–2xAl(OH)3]/waterborne polyurethane nanocomposite with superparamagnetism and flame retardancy

Based on the strong adsorption of the diphosphate group to Fe and Al ions, first, the Fe₃O₄ and Al (OH)₃ nanoparticles were modified by alendronate sodium (ALN), and organic phosphorus coated nanoparticles (Fe₃O₄‐ALN and Al (OH)₃‐ALN) with the active group ─NH₂ were prepared. Novel [xFe₃O₄–2xAl(OH)₃]/waterborne polyurethane nanocomposite with superparamagnetism and excellent flame retardancy were prepared by in situ polymerization. The experimental results showed that when the content of Fe₃O₄‐ALN increased, the M_s increased. And the saturation magnetization reached 14.35 emu/g when the Fe₃O₄‐ALN content was 10 wt%. The nanoparticle network formed by Fe₃O₄ and Al (OH)₃ can prevent the melting deformation of waterborne polyurethane (WPU) composite film and reduce the burning area. And the dual physical protective layer formed by nanoparticle network and char layer can prevent the combustible gas contacting with oxygen and giving off combustion heat, which effectively reduced the heat and smoke gas release. When the content of xFe₃O₄–2xAl(OH)₃ was 20 wt%, the oxygen index of the composite was 28.4%, and the flame retardancy of nanocomposite was classified as V‐0 rating in the UL‐94 test.     

Fabrication,morphology and mechanical properties of Al2O3–Al graded coatings on China low activation martensitic steel substrates

Al₂O₃, Al₂O₃/Al and Al₂O₃–Al graded coatings were fabricated on China low activation martensitic steel and silicon substrates by RF magnetron sputtering. The coating composition and cross‐section morphologies were investigated using X‐ray photoelectron spectroscopy, Auger electron spectroscopy and field‐emission scanning electron microscopy. The mechanical properties of the coatings were studied using nanoindentation, wafer‐curvature measurements and microscratch tests. The results show that usable Al₂O₃–Al graded coatings could be fabricated. With a more continuous compositional gradient, the interface zone was more compact. The hardness and elastic modulus of Al₂O₃–Al graded coatings were less than those of Al₂O₃ coatings, but greater than those of Al₂O₃/Al coatings. After annealing at 773 K for 3 h, the hardness of Al₂O₃–Al graded coating showed a small increase. The residual stresses in Al₂O₃–Al graded coatings declined to about 0.3 GPa, compared with the 6.6 GPa for Al₂O₃ coating. The adhesion of Al₂O₃ was improved by deposition of Al or Al compositional gradient oxide layers. Copyright © 2011 John Wiley & Sons, Ltd.     

Improving the adhesion of polymethacrylate thin films onto indium tin oxide electrodes using a silane-based “Molecular Adhesive”

Indium tin oxide (ITO) is the most commonly used transparent conducting substance. It has been used in numerous applications such as light-emitting diodes. In most applications and studies, the ITO surface is further coated with additional layers. The interface between the ITO and the coating is of utmost importance since it affects the physical and chemical properties of the final device. Improving the adhesion between ITO and a coating layer can be achieved by applying a “molecular adhesive” as an inter-phasing molecular layer. In this study, we used 3-(trimethoxysilyl)propyl methacrylate as a “molecule adhesive” for better connection between ITO and a polymethacrylate layer. The samples were studied by electrochemistry, contact angle goniometry, atomic force microscopy, and nano scratch microscopy. These studies clearly show that a simple silanization process formed a thin molecular adhesive layer, which did not influence the physical and chemical properties of the final coated electrode and at the same time increased significantly the adhesion between the ITO and the polymethacrylate coating.

     

FeOx Coating on Pd/C Catalyst by Atomic Layer Deposition Enhances the Catalytic Activity in Dehydrogenation of Formic Acid

Hydrogen generation from formic acid (FA) has received significant attention.The challenge is to obtain a highly active catalyst under mild conditions for practical applications.Here atomic layer deposition (ALD) of FeO_x was performed to deposit an ultrathin oxide coating layer to a Pd/C catalyst,therein the FeO_x coverage was precisely controlled by ALD cycles.Transmission electron microscopy and powder X-ray diffraction measurements suggest that the FeO_x coating layer improved the thermal stability of Pd nanoparticles (NPs).X-ray photoelectron spectroscopy measurement showed that deposition of FeO_x on the Pd NPs caused a positive shift of Pd3d binding energy.In the FA dehydrogenation reaction,the ultrathin FeO_x layer on the Pd/C could considerably improve the catalytic activity,and Pd/C coated with 8 cycles of FeO_x showed an optimized activity with turnover frequency being about 2 times higher than the uncoated one.The improved activities were in a volcanoshape as a function of the number of FeO_x ALD cycles,indicating the coverage of FeO_x is critical for the optimized activity.In summary,simultaneous improvements of activity and thermal stability of Pd/C catalyst by ultra-thin FeO_x overlayer suggest to be an effective way to design active catalysts for the FA dehydrogenation reaction.     

Comparative Analysis of a Solar Control Coating on Glass by AES, EPMA, SNMS and SIMS

 A solar control coating was analysed by different methods of surface analysis with respect to the layer sequence and the composition and thickness of each sublayer. The methods used for depth profiling were Auger electron spectroscopy, electron probe microanalysis, secondary neutral mass spectroscopy and secondary ion mass spectroscopy based on MCs⁺. The structure of the coating was unknown at first. All methods found a system of two metallic Ag layers, embedded between dielectric SnO_X layers. Additionally, thin Ni-Cr layers of 1–2 nm were detected on top of the Ag layers. Thus the detected layer sequence is SnO_X/Ni-Cr/Ag/SnO_X/Ni-Cr/Ag/SnO_X/glass. The Ni:Cr ratio in the nm-thin layers could be quantified by every method, the Cr fraction corresponding to less than one monolayer. We compare the capabilities and limitations of each method in routinely investigating this solar control coating. Importance was attached to an effective investigation. Nevertheless, by combining all methods, measuring artefacts could be uncovered and a comprehensive characterisation of the system was obtained.     

Corrosion and wear resistance properties of multilayered diamond‐like carbon nanocomposite coating

Multilayered diamond‐like carbon (DLC) nanocomposite coating has been deposited on silicon and stainless steel substrates by combination of cathodic arc evaporation and magnetron sputtering. In order to make DLC coating adhered to metal substrate, a chromium interlayer has been deposited with constant bias voltage of −150 V applied to the substrate. Dense multilayered coating consists of metallic or nonmetallic and tetrahedral carbon (ta‐C) layers with total thickness of 1.44 μm. The coating has been studied for composition, morphology, surface nature, nanohardness, corrosion resistance, and tribological properties. The composition of the coating has been estimated by energy‐dispersive spectroscopy. Field‐emission scanning electron microscopy and atomic force microscopy have been used to study the surface morphology and topography. I_D/I_G ratio of ta‐C:N layer obtained from Raman spectroscopy is 1.2, indicating the disorder in the layer. X‐ray photoelectron spectroscopy studies of individual ta‐C:N, CrN, and Cr‐doped DLC layers confirm the presence of sp²C, sp³C, CrN, Cr₂N, and carbidic carbon, and sp²C, sp³C, and Cr carbide. Nanohardness studies show the maximum penetration depth of 70 to 85 nm. Average nanohardness of the multilayered DLC coating is found to be 35 ± 2.8 GPa, and Young's modulus is 270 GPa. The coating demonstrates superior corrosion resistance with better passivation behavior in 3.5% NaCl solution, and corrosion potential is observed to move towards nobler (more positive) values. A low coefficient of friction (0.11) at different loads is observed from reciprocating wear studies. Wear volume is lower at all loads on the multilayered DLC nanocomposite coating compared to the substrate.     

Characterization of La0.8Sr0.2MnO3 Produced by a Reactive DC Thermal Plasma Spray System

An atmospheric pressure, reactive DC plasma spray system was used to evaluate a process for depositing porous, complex oxide thin films. A mixture of La₃O₃, SrCO₃, and MnCo₃ was used to produce a porous cathode layer for potential application in planar solid oxide fuel cells. The coated lanthanum strontium manganite (LSMO) layer made from the mixture was compared to ones generated using a pre-reacted LMSO powder made by solid-state reaction. The results showed that the crystallization of the reactive-spray formed coating layer on the zirconia substrate was higher than that of the coating layer on the mild steel from the pre-reacted LMSO powder. It is both a simpler process and gave better crystallization. The controlled porous coating layers with open pore size of less than 1 m were successfully produced in a reactive DC plasma spray system from the mixture of raw materials.     

Hexamethyldisiloxane‐modified ZnO‐SiO2‐coated superhydrophobic textiles for antibacterial application

A superhydrophobic cotton textile with high antibacterial properties has been fabricated. The cotton textile was coated through the in situ growth of ZnO‐SiO₂ nanoparticles in presence of chitosan as the template agent via a hydrothermal process at 95 °C. This process was followed by the coating of additional layers of hexadecyltrimethoxysilane (HDTMS). The obtained cotton textile showed antibacterial property against Staphylococcus epidermis and Escherichia coli with inhibition zones up to 18.26 and 8.48 mm, respectively. Scanning electron microscopy (SEM) revealed that the coating had a rough surface, which was attributed to the distribution of ZnO‐SiO₂ nanorods of hexagonal shape. This rough surface creates a superhydrophobic layer that repels the bacteria, as proven by the large water contact angle of approximately 150°. Nevertheless, the HDTMS layers prolong the durability of hydrophobicity for up to 3 h.     

Microstructural and Thermal properties of Plasma Sprayed YSZ Nano-Clusters Thermal Barrier Coatings

In the present study, a novel durable three layered thermal barrier coating (TBCs) were prepared using atmospheric plasma spray (APS) on Ni718 superalloy substrate consisting of the YSZ nano-clusters. In order to develop a functionally graded coating system, the non-transformable (t′) tetragonal YSZ nano-clusters (40 nm) were synthesized by a sol–gel process and characterized at the temperature 1200 °C for 100 h. NiCrAlY was used as bond coat. The developed coating system introduces a protective top layer of MoSi₂ (top coat) for preventing diffusion of oxygen, oxidation of the bond coating, provides thermal insulation and protection against corrosion and high temperature erosion. Microstructural, thermal oxidation resistance, thermal shock and adhesion strength of TBCs were analyzed. Different properties of as-sprayed TBCs have no significant effect on thermal oxidation property. The TBCs have shown better thermal shock resistance but lower adhesion strength than the TBCs made of without MoSi₂ layer.