Hydroxyapatite (HA) and fluorapatite (FA) coatings were deposited on Ti-6Al-4V substrates with an Nd-YAG laser and then immersed in simulated body fluid (SBF) for up to 21 days to evaluate their bioactivity. Prior to SBF immersion, the coating layer of the HA specimen had a coral-like structure, and was mainly composed of Ti, CaTiO 3 , TiO 2 , Al 2 O 3 , and Ca 2 P 2 O 7 , whereas that of the FA specimen had a dense cellular-like structure, and was mainly composed of Ti, CaTiO 3 , TiO 2 , Al 2 O 3 , and residual FA. The Ca/P ratios of the HA and FA coating layers were 7.61 and 2.12, respectively. After 21 days of immersion in SBF, only a very small amount of precipitates, mainly consisting of CaCO 3 with some hydroxycarbonated apatite (HCA) and HA, formed on the HA coating layer, whose Ca/P ratio retained a high value of 6.34. In contrast, a dense accumulation of granulated precipitates, mainly consisting of HCA, formed on the FA coating layer after just 7 days of SBF immersion, with a corresponding Ca/P ratio of 1.63. The SBF immersion test shows that FA coatings produced via an Nd-YAG laser cladding technique on a Ti-6Al-4V substrate have better bioactivity than that of their HA counterparts.

A high-performance MEMS-based gas chromatography (GC) device is proposed comprising a miniature serpentine column with dimensions of 3.2 m 9 200 lm 9 250 lm (length 9 width 9 depth) and with an integrated Pt micro heater. The column is fabricated on a Si die measuring 3.5 9 1.8 mm 2 using a wet etching process and is bonded to a Pyrex cover plate incorporating the Pt micro heater via a thermal fusion process. The experimental results reveal that an applied voltage of 9.7 V is sufficient to maintain a constant temperature of 85°C for elution purposes. In addition, it is shown that the proposed device successfully detects the concentrations of both pure and mixed samples of four volatile organic compound gases, namely acetone, toluene, methanol, and benzene. Finally, the theoretical plate number obtained by the proposed MEMS-based GC device is shown to be 2-3 times higher than that obtained from a conventional capillarybased GC system under the same injection conditions.

Most skin tribology studies gave attention on the examination of frictional properties of normal and healthy skin surfaces. This study aims to investigate the frictional and mechanical properties of skin under different load and friction conditions after removing the stratum corneum from the designated uninjured forearm tissue by a tape stripping method. The influence of water on friction coefficient was explained by using adhesion model of friction. For quantifying the amount of removed stratum corneum from the skin surfaces, an UV/vis spectrum analysis was used to measure the absorbance and pseudo-absorbance of stratum corneum on the tape. To evaluate the influence of water on friction coefficient, trans-epidermal water loss (TEWL) value of different skin conditions was assessed by water evaporation measurements. Frictional and mechanical properties of the skin surfaces were acquired via a tribometer. Results revealed that the elastic modulus of skin decreased and the friction coefficient of skin increased with the increasing of the amount of removed stratum corneum. Friction force versus normal force was presented to explain the influence of water on friction coefficient and section change phenomenon of friction coefficient under different degrees of tape strips. & 2015 Southwest Jiaotong University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Effect of solidification cooling rate on Ag 3 Sn formation and its morphological appearance in Sn-Ag based lead-free solder was investigated. Depends on cooling rate, three types of Ag 3 Sn compound with different morphologies may form by solidification. They are particle-like, needle-like, and platelike respectively. Small particle-like Ag3Sn in large amount was occurred by rapid cooling, where plate liked Ag 3 Sn was formed by slow cooling condition. Extremely slow cooling such as furnace cooling results large plate-like or pillar-like Ag 3 Sn to form, particularly in solder matrix adjacent to the solder/Cu interface. The enrichment of Sn in Cu 6 Sn 5 IMC layer formation at interface causes Sn depletion at the adjacent area near the interface. As a result, Ag atoms were enriched relatively which favored formation and growth of primary Ag3Sn in liquid phase.

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