Advanced Materials Research VII

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Authors: Thidarat Wangkham
Abstract: Materials modification with surface functional group for bioactive film or sensor surface is important in many applications. A suitable surface for each system can be shown high efficiency of detection. In this work, two different surfaces via covalent binding are created on gold substrate for finding the suitable surface in medical applications. The liver cancer biomarker, alpha-fetoprotein (AFP) was detected on two surfaces; one is carboxy dextran and another is a modified polymethyl metacrylate (PMMA). The substrates were improved by physical and chemical binding for AFP antibody immobilization. Contact angle and surface Plasmon resonance (SPR) were used to study the characteristic of surfaces. The result was found that the carboxy dextran gave higher detection than PMMA. Moreover, the dextran surface was studied in real serum samples. It was shown the significantly different between positive and negative AFP serum which is preliminary results for testing in more clinical samples further.
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Authors: I Hao Chen, Ching Ming Chien, Chun Ting Wang, Chih Ling Huang, Chih Kuang Wang, Yur Ren Kuo
Abstract: Chitosan and gelatin are potential wound dressing materials. However, chitosan takes too much time to degrade and gelatin degrades too fast. As a result, chitosan and gelatin are blended to adjust their degradation rate. The degree of degradation test by means of weight loss and thermogravimetric analyzer after being incubated with lysozyme, which is a common enzyme in body fluid. Optical microscopy was used to observe the materials morphology after immersed in water. Finally, fibroblast cells were cultured with various material extracts to examine cell adhesion In Vitro. Cell adhesion tests showed there are no negative effect on cells. Therefore, there is no cell toxicity of chitosan on cells. Chitosan and gelatin can be promising wound dressing raw materials in future.
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Authors: Patcharaporn Thitiwongsawet, Choolchinda Chandratat, Sutee Boonnoppornkul
Abstract: Sodium salicylate (SS), a non-steroidal anti-inflammatory drug, was loaded into starch-based hydrogels and the release characteristics of SS therefrom was studied. The hydrogels were prepared from wheat and arrowroot starches and crosslinked with either glutaraldehyde or sodium tetraborate decahydrate (borax). SS was loaded into hydrogel at concentrations of 10 and 20%w/w based on dry weight of sample. The study of release characteristics was carried out by total immersion method for 24 h in an acetate buffer solution (pH 5.5) at 32°C as the same condition of human skin. A burst release of SS at the initial time followed by a gradual release to reach a plateau was observed. The maximum amounts of SS released from the hydrogels were about 8-22 mg. The amount of water retention of hydrogels was also determined at the same condition with that of the study of release. The hydrogels with the greater amount of water retention showed the higher release of SS. The hydrogels crosslinked with borax had higher amounts of SS released than those crosslinked with glutaraldehyde. The hydrogels containing 20% SS-loaded showed higher amounts of SS released than those containing 10% SS-loaded. The hydrogels prepared from arrowroot starch showed higher amounts of SS released than those prepared from wheat starch. From the study of release kinetics based on the Korsmeyer-Peppas model, the exponents of release (n) of all specimens were close to 1 which indicated Case II diffusion.
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Authors: Kyung Won Kim, Brandon Y. Boeur, Sin Jae Hyun, Cheol Woo Park
Abstract: In the present study, we experimentally investigated the aerosol-particle sustaining features of a porous-walled rubber foam tube model according to outlet humidity and temperature variations. An oleic acid aerosol is used as the inlet working fluid and the embedded particle diameters are in the range of 6–10 μm. To analyze particle size distribution, a wide-ranging particle spectrometer is employed, and particle sizes are measured at the inlet and outlet of the tube. Variance analysis is performed to evaluate the significance level of various tube-wall conditions, including dry and moist aerosol conditions at room and body temperatures. For the cases of larger particle sizes, the sustaining rates are increased when the porous wall condition is moist and at body temperature.
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Authors: Wei Wen Lin, Wei Fang, I Hao Chen, Tze Yo Hung, Chih Ling Huang
Abstract: Bioactive glass (BG) is characteristic of its great biocompatibility as well as osteoconductivity. Application of BG after surgery (e.g., tumor resection) aids rehabilitation of previously traumatized area, promotes bone regeneration, and prevents aggravation of wounds. In this in vitro study, bioglass nanoparticles (BGN) were successfully produced via sol-gel method. We observed the morphology of BGN through Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Particle size was measured by Dynamic Light Scattering (DLS): 182.9 nm ± 37.7 nm in diameter, which corresponds to images obtained by SEM and TEM. We then synthesized BGs containing different proportions of Ca and P ions. Under different pH values, gels with various morphologies were formed.
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Authors: Annie Yu, Pui Ling Li, Kit Lun Yick, Sun Pui Ng, Joan Ne Yip
Abstract: Thermal comfort is an important criterion for the overall wear comfort of shoes. In this study, the materials properties, the microclimate of two types of sport shoes made of leather and mesh spacer fabric were evaluated. The human subjective sensations when wearing the shoes were investigated. Ten youth and ten elderly subjects have taken part in wear trials that consist of three activities: sitting, walking and running, while wearing the two types of shoes and in the barefoot condition. The order of the wear trials is randomized for each subject. The temperature and humidity at six locations of the foot were recorded during the wear trials and subjective perceptions of thermal, humidity and comfort were rated at the end of each wear trial. The results show that the leather sports shoes trap more heat and moisture on the feet than the mesh fabric sports shoes. The effect is more significant during running. Therefore, the shoe upper materials not only affect the temperature and humidity of the foot dorsal but also those of the foot plantar. Gender, foot condition and type of activity have a significant linear relationship with thermal, humidity and comfort perceptions towards footwear. Age does not have any impact on the three subjective perceptions. The findings in this study can therefore act as a reference source for the design and development of footwear that have better wear comfort.
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Authors: Seung Min Oh, Sun Ig Hong
Abstract: Microstructure and mechanical properties of cast and cold-rolled equitomic CoCrFeCuNi alloy in which Mn was substituted by Cu from Cantor alloy was studied. The separation into two solid solutions (Cr-Co-Fe rich and Cu-rich phases) were observed in CoCrFeCuNi. Coarsening and widening of interdendritic Cu-rich phase after homogenization was observed after homogenization, suggesting Cu-rich phase is thermodynamically stable. The compressive stress-strain curves of homogenized cast CoCrFeCuNi alloy exhibited the reasonably high strength and excellent deformability for the cast alloy. The yield strength increased up to 960MPa after cold rolling from 265MPa of the homogenized cast alloy. The significant increase of yield strength is thought to be associated with the alignment of Cu-rich second phase in addition to cold work dislocation storage after cold rolling.
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Authors: Tosapolporn Pornpibunsompop, Purit Thanakijkasem
Abstract: High temperature corrosion of 310S austenitic stainless steel in simulated rocket combustion gas at 900 degree Celsius was investigated and discussed in this paper. 310S austenitic stainless steel was chosen because it was used for building some components of a rocket launcher. The corrosive atmosphere was prepared by mixing of hydrochloric acid and distilled water with 5.5 mole per liter then, boiling that solution and feeding into a corrosion testing chamber. The chamber was set up at 900 degree Celsius with duration 210 hrs. After testing, the corroded specimen was microscopically characterized by OM and SEM/EDS techniques. The corrosion layer was classified into three main sublayers: peeling-off scale, external corrosion sublayer, and internal corrosion sublayer. The local chemical information was analyzed by XRD (in case of peeling-off scale) and SEM/EDS (in case of external and internal corrosion sublayers). The peeling off scale mainly comprised Fe2O3 and Fe21.3O32 ferrous oxides because they needed much oxygen consumption to exist. In case of external and internal sublayers, there were a lot of pore tunnels and corrosion products. Chlorine and/or hydrogen chloride would penetrate through a passive film and, then, metal chlorides was formed on both external and internal corrosion sublayers. Metal chlorides would volatile because of their lower evaporation temperature than the testing temperature. Moreover, they were oxidized by oxygen in wet condition and resulted metal oxides mostly remaining on the external corrosion sublayer.
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Authors: Jiang Li, Fu Guo Li, Xin Kai Ma, Ming Jie Zhang, Zhan Wei Yuan
Abstract: In order to study the micromechanical behaviour of the forged Ti-1023 titanium alloy, micro-indentation experiments of the forged Ti-1023 titanium alloy were performed with various maximum indentation loads from 500 mN to 4000 mN and various loading speeds from 5.06 mN/s to 51.85 mN/s. Using the experimental data, the non-destructive instrumental approach was applied to indicate the mechanical properties just like the Young’s modulus E, microhardness H, initial yield stress σy and strain hardening exponent n using the P-h curves from the tests. The result showed that the value of the indentation Young’s modulus basically remain unchanged in the range from 110 GPa to 150 GPa and H decreased with the increase of the load, the micro-indentaion plasticity constitutive equations were obtained by using Hookean elastic and power-law plastic stress-strain equations.
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Authors: You Bin Kang, Seung Min Oh, Kap Ho Lee, Sun Ig Hong
Abstract: Stress-strain responses and microstructure of multi-phase CoCrCuMnNi and CoCrMnFeCu alloys in which Fe or Ni was replaced by Cu from Cantor alloy were studied. The deformation mechanisms of CoCrCuMnNi and CoCrMnFeCu were observed to be influenced by the presence of brittle sigma phase and the separated Cu-rich and the matrix phase. CoCrCuMnNi exhibited the relatively lower strength and excellent deformability, while CrMnFeCoCu alloy exhibited higher strength and lower ductility. The higher strength and the lower ductility of CoCrCuMnNi is associated with the presence more frequent and coarser sigma phase than those in CoCrCuMnNi.
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