Applied Mechanics and Materials Vol. 709

Abstract: The compositional dependences of luminescence properties and light yield were studied in Ce³⁺ -doped Y₁Gd₂Al_5-xGa_xO₁₂ (x = 2, 3, 4) single crystal scintillators. The Gd³⁺→ Ce³⁺ energy transfer was evidenced by photoluminescence excitation spectra of Ce³⁺ emission. With increasing Ga content in the garnet host, the Ce³⁺ luminescence from the lowest 5d level (5d1) was blue-shifted due to the decrease in the crystal field splitting of the 5d levels. High light yield (LY) value of ~36,000 ph/MeV was obtained for a Y₁Gd₂Al₂Ga₃O₁₂:Ce sample under excitation with 662 keV γ-rays. The decrease of LY value was also observed with higher Ga content due to the thermal ionization from the 5d1 level to the conduction band.

Abstract: Al-5Ti alloy wires with fine grain microstructures were prepared via a continuousequal channel angular pressing process with 1 to 4 passes in a castingextrusion (CASTEX) equipment equipped with a multi-channel die. The evolutionof Al-5Ti alloy microstructure during each forming pass was investigated. Thefracture of TiAl₃ particle phases during deformation, as well astheir interaction with deformation, was also analyzed. The results proved that thecontinuous equal channel angular pressing process can effectively refine Almatrix structure and TiAl₃ particle phases, improve thestrengthening effect of TiAl₃ reinforcing particles on the matrixmetal and produce wires with fine grain microstructure.

Abstract: Aluminum (Al) alloys have great potential as ideal structural materials because of their high specific strength and stiffness. However, Al alloys exhibit poor ductility at room temperature. Enhancing the formability is a very important and challenging problem to both automotive and manufacturing engineers. In this study, the electro-plastic effects, which is first discovered in 1960s, of 5xxx Al alloy sheets are investigated to improve the formability. To begin with, a test system is built up to carry out the tensile test with heavy electric current flowing through the specimen. The evolutions of the flow stress and the electric resistivity are obtained using this test system. The significant decrease in the flow stress caused by the heavy flowing through current is observed.

Abstract: The article investigates the changing in the structure and phase composition of the R6M5 high-speed steel surface layer after electrolytic-plasma nitriding. It is found that after electrolytic-plasma nitriding on the R6M5 steel surface, modified layer is formed, which consist from a diffusion layer. It was showed phase composition of difysion layer is changing depending on the nitriding. It is found that electrolytic-plasma nitriding lead to accelerated formation of the modified layer. It is determined that after electrolytic-plasma nitriding on the high-speed steel surface, modified layer is formed, consisting only of the diffusion layer.

Abstract: The current situation and production methods of vulcanized rubber powder at home abroad were summarized in this paper. The common production mathods always include RAPRA, anrbient grourd and cryogenic ground. For the current status of the domestic and overseas cryogenic ground technolgy,the prospects of grounding waste rubber by LNG cryogenic energy were put forward.

Abstract: Acanthamoeba spp. is the free living protozoain the environment which are opportunistic pathogens of human [1]. Acanthamoeba spp. is the causative agents of Acanthamoeba keratitis (AK)[2]. The risks of AK increased by using contact lens are not good hygiene. Antiamoebic therapy were biguanides chlorhexidine (BCH) or polyhexamethylene biguanide (PHMB) which were not effective enough to kill Acanthamoeba cysts [3]. Reported, plant for protected glaucoma, anti-inflammatory and analgesic properties are Peperomia pellucida in Piperaceae family. This interesting of studied P. pellucida for antiamoebic. Dried plant of P. pellucida was chromatographic by Diaion HP20 and fractionated into methanol : water (1:1, FrI), methanol (FrII) and ethyl acetate (FrIII). The methanol fraction (FrII) was damaged morphological and changed structural of Acanthamoeba cysts, detected by toluidine dye staining are shown under the light microscope, in IC₅₀ 29.28±3.64%.The active methanol fraction was studied by chromatography, gave four fractionated fraction A1-A4. A1 led to the isolation of compounds 1, A2 and A3 isolated compounds 2-5. They were identified using spectroscopic methods.

Abstract: Using solid phase extraction and high performance liquid chromatography (HPLC), this paper studies the adsorption capability of activated carbon to phenol. The phenol wastewater is simulated with raw water and pure water, respectively. In detail, we examine impact factors including adsorption time, activated carbon dosage, equilibrium concentration of phenol. Using the adsorption principles from the aspect of kinetics, our study shows that adsorption of powder activated carbon to phenol conforms to the Fran Delhi Freundrich adsorption model.

Abstract: Through the application of electrochemistry, CO₂ was captured in an eutectic mixture of Li-Na-K carbonates before forming a nanosized amorphous carbon powder. The carbon powder was used to study on the absorption on tetracycline in aqueous solutions. At 298K, the maximum adsorption capacity of tetracycline reached 127.76mg/g. The sorption data could be well fitted into pseudo-second-order kinetics and Frendlich sorption isotherms. The adsorption process was endothermic, spontaneous and irreversible.

Abstract: With attempt of using all-ceramic fixed partial denture (FPD) on posterior teeth region while the high-strength ceramics themselves cannot be guaranteed for the strength of the FPD, the length of pontic of FPD is considered to be one of the significant factors that influence the FPD strength. This study was therefore aimed to use FEA to simulate the actual laboratory test in investigating whether a 3-unit all-ceramic FPD on posterior teeth could tolerate the maximum normal bite force, which is approximately 665 N. The FPD was designed to be fabricated with In-Ceram^® zirconia and have pontic length of 11 mm. The simulation was performed using a 2-dimensional finite element analysis (FEA) on ANSYS software. Lower second premolar and second molar teeth were placed at 11 mm apart in acrylic resin block. The teeth were prepared to be abutments of FPD. The result of the FEA showed that the FPD could tolerate the force exceeded the maximum normal bite force on molar region in human. This is corresponding with the previous study performed in the laboratory presenting that the FPD can withstand the load of greater than 1000 N. As the FEA has given the relevant result to that of the laboratory test, further investigations are anticipated to be performed to achieve the optimum length of a 3-unit all-ceramic FPD on posterior teeth fabricated in various systems.

Abstract: Biopsy is a common medical procedure to treat and diagnose prostate cancer and breast cancer. Needle insertion is a critical step in biopsy, but the inserting force has a big effect on precision of needle insertion. A new method is presented to reduce the penetration force, and then improve the precision of needle insertion in this paper. Preloaded piezo actuator was introduced to provide biomimetic vibration for needle during needle insertion into a pork liver, just as a fascicle insertion into the skin by a mosquito. The experimental results showed that the penetration force was reduced 26.7% compared with the force without biomimetic vibration.