Formation,densification and properties of sol–gel TiO<Subscript>2</Subscript> films prepared from triethanolamine-chelated soluble precursor powders

Amorphous, soluble powders were synthesized with triethanolamine (TEA) as chelating agent as precursors for TiO₂ sol–gel solutions. Dip coating on glass substrates and subsequent annealing yielded thin films with excellent optical properties. Furthermore as-dried films were scraped of substrates, annealed at different temperatures and characterized in order to investigate the structural changes during processing. The observations were systematically compared with previous studies on precursor powders based on acetylacetone. Results indicate that triethanolamine provides both a sufficient hydrolytical stability of the Ti-precursor during coating and an adequate plasticity of the film material throughout thermal densification. These characteristics significantly improve the practical workability of the respective process. Additionally former assumptions regarding the relationship between film properties and intermediate structural features were verified and refined.     

Evaluation of a mathematical model using experimental data and artificial neural network for prediction of gas separation

In recent times, membranes have found wide applications in gas separation processes. As most of the industrial membrane separation units use hollow fiber modules, having a proper model for simulating this type of membrane module is very useful in achieving guidelines for design and characterization of membrane separation units. In this study, a model based on Coker, Freeman, and Fleming＇s study was used for estimating the required membrane area. This model could simulate a multicomponent gas mixture separation by solving the governing differential mass balance equations with numerical methods. Results of the model were validated using some binary and multicomponent experimental data from the literature. Also, the artificial neural network （ANN） technique was applied to predict membrane gas separation behavior and the results of the ANN simulation were compared with the simulation results of the model and the experimental data. Good consistency between these results shows that ANN method can be successfully used for prediction of the separation behavior after suitable training of the network     

Effect of nano‐modified SiO2/Al2O3 mixed‐matrix micro‐composite fillers on thermal,mechanical, and tribological properties of epoxy polymers

Thermo‐mechanically durable industrial polymer nanocomposites have great demand as structural components. In this work, highly competent filler design is processed via nano‐modified of micronic SiO₂/Al₂O₃ particulate ceramics and studied its influence on the rheology, glass transition temperature, composite microstructure, thermal conductivity, mechanical strength, micro hardness, and tribology properties. Composites were fabricated with different proportions of nano‐modified micro‐composite fillers in epoxy matrix at as much possible filler loadings. Results revealed that nano‐modified SiO₂/Al₂O₃ micro‐composite fillers enhanced inter‐particle network and offer benefits like homogeneous microstructures and increased thermal conductivity. Epoxy composites attained thermal conductivity of 0.8 W/mK at 46% filler loading. Mechanical strength and bulk hardness were reached to higher values on the incorporation of nano‐modified fillers. Tribology study revealed an increased specific wear rate and decreased friction coefficient in such fillers. The study is significant in a way that the design of nano‐modified mixed‐matrix micro‐composite fillers are effective where a high loading is much easier, which is critical for achieving desired thermal and mechanical properties for any engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.     

IR Reflective LaPO4 Ceramic Colorant Reinforced Polymer Composite Coatings on Glass and Metal Substrates for Heat Management Applications

LaPO₄ ceramic colorants were processed in the vibrant shades of green and brick red, and subsequently embedded in polymer resins for the fabrication of heat management coatings. The IR/UV shielding characteristics of these ceramic colorants and polymer coatings were analysed and it was found that the ceramic dispersoids enhance the IR reflectance quality of polymer resins by 20 to 25 times. The nano ceramic green colorant-reinforced polymer coating on glass panels offers the stringent property, i. e., optical transparency and heat reflectance combined, when exposed to direct sunlight. Other photophysical properties were also studied and analysed. The brick red colorant entrenched resin coating on metal substrate offered heat reflectance and corrosion resistance characteristics. XPS studies provided the chemical environment of the systems. Surface morphology, crystallinity and particle size of the products were investigated using SEM, TEM, XRD and DLS techniques. The polymer resin coating of these ceramic colorants offers thermal stability and colorfastness properties.     

Anti-soiling effect of porous SiO<Subscript>2</Subscript> coatings prepared by sol–gel processing

Thin films being composed of a nanoporous SiO₂ network and silica nanoparticles were prepared on glass substrates by sol–gel processing. The surfaces combine anti-reflective (AR) and anti-soiling properties as demonstrated in laboratory testing and long term outdoor exposure. Films were characterized by scanning electron microscopy (SEM). It is shown that both, the structure of the nanoporous matrix as well as the particle density, contribute to this effect, the influence of relative humidity (RH) during dust exposure was investigated. Due to their generally improved solar transmittance and dust-repellant properties the coatings are believed to have a vast potential for many photovoltaic and solar thermal applications.     

Ring-resonator-based frequency-domain optical activity measurements of a chiral liquid

Chiral liquids rotate the plane of polarization of linearly polarized light and are therefore optically active. Here we show that optical rotation can be observed in the frequency domain. A chiral liquid introduced in a fiber-loop ring resonator that supports left and right circularly polarized modes gives rise to relative frequency shifts that are a direct measure of the liquid's circular birefringence and hence of its optical activity. The effect is in principle not diminished if the circumference of the ring is reduced. The technique is similarly applicable to refractive index and linear birefringence measurements.     

Performance Optimization for the Parallel Gauss–Seidel Smoother

Simulation, e.g., in the field of computational fluid dynamics, accounts for a major part of the computing time on highperformance systems. Many simulation packages still rely on Gauss–Seidel iteration, either as the main linear solver or as a smoother for multigrid schemes. Straight-forward implementations of this solver have efficiency problems on today's most common high-performance computers, i.e., multiprocessor clusters with pronounced memory hierarchies. In this work we present two simple techniques for improving the performance of the parallel Gauss–Seidel method for the 3D Poisson equation by optimizing cache usage as well as reducing the number of communication steps. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)