Electrochemical behaviour of Ti–25Nb–3Mo–3Zr–2Sn biomedical alloy in different simulated physiological environments

The electrochemical corrosion behaviour of biomedical Ti–25Nb–3Mo–3Zr-2Sn (TLM) alloy was investigated in various simulated body fluids at 37±0·5°C utilising potentiodynamic polarisation and current–time curves. The Ti–6Al–4V (TC4) alloy was also investigated to make a comparison. The different simulated body fluids comprised of 0·9%NaCl saline, Hank’s and Ringer’s solution were employed. The effect of heat treatment on the electrochemical behaviour of the TLM alloy was also considered. It was discovered that all the test specimens were passivated once immersed into the simulated body fluids. It was also found that the TLM alloy has poorer corrosion resistance in Hank’s solution, due to the chemical composition of the Hank’s. After different heat treated, the TLM alloy had different phases and microstructure, and the corrosion behaviour of the TLM alloy was different. In this study, after the heat treatment of 760°C/1 h/AC+550°C/6 h/AC, the TLM alloy had better corrosion resistance. Owing to the corrosion resistance of the TLM alloy was influenced by numerous factors, such as microstructure and the chemical composition of electrolyte, the corrosion behaviour of the TLM alloy is complex. By comparing with the corrosion behaviour of the TC4 alloy, the TLM alloy has poorer corrosion resistant than the TC4 alloy under the same conditions. But the current–time curves of the TLM alloy were more stable than these of the TC4 alloy with further experiments, because of the more passivation film on the surface of the TLM alloy.     

Analysis of the mechanism and failure mode of landslides subjected to transient seepage in a Piedmont region of Nanjing area

Bulletin of Engineering Geology and the Environment - The landslide mechanism and failure mode of the gently sloping Piedmont region are analyzed in Fangshan and Zhutoushan hills in the...     

冷加工制备医用铂钨丝材的研究

铂钨(PtW)合金是一种优良的生物医用材料,铂钨丝材可制成栓塞弹簧圈,用于治疗脑动脉瘤。由于铂钨属难熔合金,且开坯极易开裂。采用非自耗真空电弧熔炼方法制备铂钨合金铸锭,通过小变形量轧制并配以中间热处理,使铸锭发生塑性变形,结合后续的拉制及不同热处理工艺,采用光学显微镜、扫描电镜对微观组织进行观察,并研究铂钨合金丝材在不同热处理条件下的力学性能变化,成功制备出满足生物医用要求的铂钨超细丝材。     

Effects of TiO2 additive on ultra-low-loss MgO–LiF microwave dielectric ceramics

MgO ceramics have good microwave dielectric properties, but the high sintering temperatures limit its application. The effects of TiO₂ additive on the phase composition and microwave dielectric properties of MgO ceramics with 4mol%LiF were investigated by solid state reaction method. TiO₂ and MgO form Mg₂TiO₄ in a magnesium-rich environment with 4mol%LiF at about 900 °C, which as a solid solution or second phase had a huge impact on MgO ceramic with 4mol % LiF. When the content of TiO₂ less than 2mol %, Mg₂TiO₄ as a solid solution in MgO ceramics, which made the grain of MgO larger. When the content of TiO₂ more than 2mol %, Mg₂TiO₄ as a second phase in MgO ceramics, which made the microwave dielectric properties of MgO ceramics bad. Typically, the MgO-4mol%LiF-0.5mol%TiO₂ ceramic sintered at 1075 °C for 6 h acquired the best dielectric properties: ε_r = 9.7, Qf = 617,000 GHz and τ_f = −59.49 ppm/°C.     

A hybrid fuel cell system integrated with methanol steam reformer and methanation reactor

In this paper, a hybrid fuel cell system integrated with methanol steam reformer and methanation reactor is demonstrated. Methanol steam reformer employed in this system is to produce hydrogen-rich reformate in connection with a methanation reactor to reduce the carbon monoxide content effectively, and the reformate gas is sent into a low-temperature polymer electrolyte fuel cell for direct electric power generation. The optimum conditions (temperature, water to methanol ratio, and space velocity) for methanol steam reforming (MSR) reaction and methanation (MET) reaction are verified by experiments. A comparison between pure hydrogen, reformate surrogate, and actual reformate is performed. The results show that the power density of this hybrid system achieves 245.2 mW/cm² while it achieves 268.8 mW/cm² when employing pure hydrogen as the fuel. An alternative novel method to solve the problem of hydrogen storage and transportation is provided and the in-situ hydrogen production and utilizing through low-temperature fuel cell system is realized, which is helpful to accelerate the commercialization process of the fuel cell.     

Relationship between pungency and food components – A comparison of chemical and sensory evaluations

The influence of food ingredients (water, starch, fat, and sugar), individually and in combination, on the sensory perception of the pungency of capsaicin was studied in model food systems using the time-intensity method. Furthermore, the transferability of the results obtained using model food matrices to complex matrices, such as convenience salsas, was investigated. Significant differences between the samples (p < 0.05) were examined by analysis of variance (ANOVA) followed by the Tukey-HSD post hoc test. A highly complex matrix and a high starch content reduced the perception of pungency in both the model food matrices and the convenience salsa products. Therefore, the time-related maximum intensity of pungency (I_max) was affected by other factors in addition to the capsaicin concentration.The total capsaicinoid content in the salsas was quantified by high-performance liquid chromatography–mass spectrometry (HPLC–MS) and correlated to the results of the sensory evaluation. The best correlation (R² = 0.8029) was observed for the total capsaicinoid content and the maximum intensity of pungency (I_max) in comparison to the duration of the total pungency perception T_Dur (R² = 0.5176) and the area under the curve (R² = 0.6898). The calculated regression models serve as an example of how empirical calculations can be generated and used in a specific context.     

Confined space reduced graphite oxide doped with sulfur as metal-free oxygen reduction catalyst

Reduced GO in confined space of silica gel nanopores doped with sulfur shows high catalytic activity for oxygen reduction reaction (ORR) in alkaline medium and exhibits a superior tolerance to the presence of methanol. Even though the partially reduced GO with hydroquinone structures is a good catalysts for ORR, it shows instability in KOH. The good performance of S-doped material is linked to the coexistence of sulfur and oxygen on the surface in equal atomic quantities and a unique porosity being the replica of the silica pores. The former leads to the positive charge on the carbon atoms, which are the reaction sites. Hydrophobicity of the surface and small pores enhance adsorption of O₂.     

我国包装装潢设计存在的问题与探讨

通过对周边琳琅满目的包装装潢产品细细感悟的基础上,了解我国的包装装潢设计还存在着许多问题。指出其水平还处于初级阶段,普遍雷同,中国特色不强烈,进一步分析了这种问题存在的主客观原因。最后通过对两个优秀包装装潢设计的分析,发现只有立足于我国文化传统,并融入当代意识才能设计出在世界上站得住脚的包装装潢设计,由此来探讨我国包装装潢设计未来发展之路。     

石油集团企业的云计算战略

结合石油集团企业信息化的特点,从概念层面、商业层面和技术层面对云计算进行详细的介绍和分析。提出了石油企业实施云计算战略的三个阶段,即构建—拓展—提升,并指明在实施过程中决定成败的几个要素即性能、时效性、自动化和安全性。旨在引起石油企业对云计算的关注,引发战略性思考。     

用Excel辅助高职数学教学的实践与探索

Excel不仅是一款优秀的办公自动化软件,而且可以较好地辅助于高职数学教学。通过大量实例,以图表的方式列举了Excel在讲解两个重要极限、零点定理、研究函数性态和计算曲边梯形面积时的具体操作。