Advanced Materials Research Vol. 1088

Abstract: The growth of microarc oxidation (MAO) coatings on aluminum substrates was controlled by different mono-component solutions, involving (NaPO₃)₆, Na₃PO₄, Na₂SiO₃ and Na₂MoO₄ aqueous electrolyte. The results show that (NaPO₃)₆ solution can accelerate the growth of MAO coating, revealed by the maximum coating thickness of 12.1 μm; and meanwhile, Na₂SiO₃ solution favors the doping of solute elements during MAO, suggested by 10.75 at.% Si in coating. Furthermore, the variety of mono-component solution also affects the porous structure of MAO coating. It is assumed that the property of coating/solution interface is influenced by solution variety, while the interfacial property determines the solidification of ceramic particles and the adsorption of solute anion during microarc discharge, thus realizing controlled growth of MAO coating.

Abstract: An amino protection method was developed in which phthalic anhydride was used as the amino protection group, N,N-dimethylformamide (DMF) as solvent, L-threonine and L-serine with hydroxyl groups in side chain as the protected amino acids.The structures of products were confirmed by IR、1H NMR and 13C NMR. It is an efficient and simple protection method of amino acids with a hydroxyl group in the side chain.In addition, the synthetic method avoids the side reaction and significantly improves reaction yields(over 90%).

Abstract: A novel efficient method for the synthesis of 4-amino-5- substituted-1,2,4- triazole -3-thione was developed in which substituted aromatic/aliphatic acids with symmetrical dithiocarbohydrazones were used as starting materials and phosphorus pentachloride was used as catalyst.The structures of these products were confirmed by melting point determination, IR, 1H NMR and elemental analysis. This is a novel and cost-effective synthetic method. In addition, the synthetic method avoids the use of organic solvents and significantly improves reaction yields.

Abstract: Spherical YAG:Ce³⁺ phosphors were synthesized by three different routes namely sol-gel method, co-precipitation method and solvethermal method. The microstructure, crystallization and luminescent properties of the phosphors were studied in order to find the best processing parameter for spherical shape and good luminescence properties of YAG:Ce³⁺ phosphor. Adding citric acid to the precursor solution resulted in the formation of spherical particles in sol-gel method. YAG:Ce³⁺ phosphor made by co-precipitation method was separated with PEG2000, and its spherical particles of size was around 500nm. The hydro-thermal method could get perfect spherical appearance, but it needed heat treatment improve the luminescence property.

Abstract: A metal-semiconductor-metal photoconductive detector was fabricated using Ce-doped ZnO nanofibers synthesized by electrospinning and calcinations. UV photocurrents were carried out to study optoelectronic properties of Ce-doped ZnO nanofibers. The current-voltage (I–V) characteristics of photodetector device were analyzed under different wavelength UV illumination. The photocurrent increased by about 300 times under UV illumination. Results showed that the photocurrent of the device increased with the decrease of the wavelengths. A maximum photocurrent and photo-responsivity was observed at 365 nm, 308 nm, 254nm, respectively, under 30 V bias. The response and recovery time of the nanofibers was 16 s and 16 s at 365 nm, 10 s and 12 s at 308nm, 4 s and3 s at 254nm under 30 V bias, respectively.

Abstract: In this work I present fluorescent carbon dots (CDs) prepared by facile and inexpensive synthesis by hydrothermal carbonization from cationic surfactant cetylpyridinium chloride (CPC). These CDs show tunable photoluminescence as well as long-term colloidal stability. Moreover, CDs exhibit high selectivity and sensitivity towards Fe³⁺ ions. Therefore a specific quantitative method is proposed for the determination of Fe³⁺ ions based on fluorescence quenching of CDs.

Abstract: The constants of acid-base equilibrium were estimated with spectroscopic method at the ground (S₀) and at the fluorescent (S₁^fl) states. The constants of acid-base equilibrium for Franck-Condon excited states (S₁^F-C) were estimated from spectral shifts for basic and acid forms. This results are compared with quantum yields of photostability of complexes in neutral solvents. The mechanisms of complexes protonation are discussed dependence from the structure of ligands.

Abstract: The article deals with producing diamondlike-PVD-coatings based on carbon: a-C and a-C:H and MeN/CNx. These types of coatings were prepared by magnetron sputtering materials in vacuum. The results of experimental studies of their mechanical and tribological properties and recommendations for use in industry

Abstract: The work evaluates the possibility of the use the exhauster powder generated in the foundry process in ceramic mass atomized semigre type. The raw materials used were semi-stoneware kind atomized powder used on the coating ceramic manufacturing and dust exhaust byproduct supplied by a foundry industry both from brazilian industries . Tests were conducted using a heating rate of 10o.C / min and oxidant and / or inert atmosphere. Specimens contained different amounts of byproduct to the extent of 30% by mass, in order to verify the maximum addition of byproduct and were used in order to analyze the technological properties evaluation (water absorption linear shrinkage, bulk density). at the temperature of 1100 ° C showed higher difference between the results obtained and 1200o C this difference decreased.

Abstract: Woven fiber reinforced polymer composites plays major role in structural applications. Structures subjected to dynamic situations, this leads to increased attention in finding characteristic behaviour/performance of FRP composites beams under vibrating conditions. The objective of this work is to understand and investigate the influence of cross sectional shapes of beams on successive vibration resonance frequencies and its damping performance under cantilever end conditions. The beams were fabricated by hand lay-up method in two different modulus material and cross sections like I and channel; maintaining uniform cross sectional area and moment of inertia apart from length of the beams using woven carbon fibre. The investigation was performed by impulse frequency response method using standard test procedure on low modulus Glass/epoxy composite beams and compared with high modulus Carbon/epoxy beams. Frequency response curve of I and channel shaped beams were compared for their damping performance. The modal frequencies of all fabricated beams were obtained using MEScopeVES® software and modal resonant frequencies, loss factor were compared against shapes.