Experimental study on control fins of a small flying vehicle using piezo-composite actuators

A camber morphing control fin design and an all-moving control fin design using piezo-composite unimorph actuators are presented in this paper. The control fin of a small flying object is usually actuated using a servo motor system with an electromagnetic motor. Much research has been conducted to solve the structural complexity of servo actuation systems to convert the rotation of a servo motor to a linear actuation motion. To simplify this structural complexity, several types of smart actuators have been developed, such as bimorph or unimorph actuators with piezoelectric material layers and shape memory alloy actuators. In this study, a camber morphing type control fin and an all-moving type control fin actuated using piezo-composite actuators are designed to evaluate their ability to simplify the structural complexity of the gear transmission and electromagnetic servo motor system or hydraulic actuator system. Within the skin of the control fin, a piezo-composite actuator is mounted and the other end inserted in a slot of the control fin. As the piezo-composite actuator is excited by an electric field, the pitch angle of the control fin is changed. Experimental testing for the pitch rotation angle of a control fin in a 450 V electric field showed the deflection angle of the camber morphing control fin was 1.4° and the rotational angle of the all-moving control fin was 5.4°, which is obtained from the rotation angle magnification linkage structural system.     

Antimicrobial effect of an Undaria pinnatifida composite film containing vanillin against Escherichia coli and its application in the packaging of smoked chicken breast

To develop a value‐added product, we used the under‐utilised seaweed Undaria pinnatifida as a source material for the fabrication of a biodegradable film by extracting U. pinnatifida protein (UPP). UPP/gelatine composite films with different constituent ratios were prepared. In addition, the UPP/gelatine composite films containing vanillin (0.05%, 0.1% and 0.5%) were prepared as antimicrobial packaging material. To evaluate the utility of the UPP composite film containing 0.5% vanillin as food packaging material, smoked chicken breast samples inoculated with Escherichia coli were packed with the film and stored at 4 °C for 10 days. It was observed that packaging of smoked chicken breast with the UPP composite film containing vanillin decreased the population of the inoculated E. coli by 1.12 log CFU g^?1 compared with that in the control sample. Thus, the UPP/gelatine composite film with added vanillin can be utilised as a packaging material for smoked chicken breast.     

320排动态容积CT检测肾动脉解剖形态在介入治疗中的应用价值

【摘要】 目的 评价320排640层动态容积CT检测肾动脉解剖形态的优势及在介入治疗中的应用价值。方法 回顾性分析200例中上腹部320排动态容积CT增强扫描动脉期资料，容积数据通过ViTAL工作站进行后处理，结合容积再现、最大密度投影、多平面重建及曲面重建成像进行统计分析，检出肾动脉变异和疾病患者，并对肾动脉变异类型和病例进行分类分析。结果 200例患者中99例（49.5%）存在变异肾动脉，其中62例（31.0%）有副肾动脉，57例（28.5%）有肾动脉早发分支。共发现142支变异肾动脉，变异率为35.5%（142/400），左侧为38.5%（77/200），右侧为32.5%（65/200）；副肾动脉80支（56.3%），肾动脉早发分支62支（43.7%）；起源于腹主动脉78支，起源于肾动脉主干62支，起源于肠系膜上动脉1支，起源于右膈下动脉1支。200例患者中检出11例13支肾动脉狭窄，5例肾肿瘤。结论 320排动态容积CT增强检查扫描时间短，辐射剂量低，既能准确评估肾动脉变异类型，又能清晰显示各类变异细节，为临床肾脏病变介入治疗及其它外科治疗提供更多解剖学信息。

     

Steam reforming of liquefied natural gas (LNG) for hydrogen production over nickel–boron–alumina xerogel catalyst

A series of mesoporous nickel–boron–alumina xerogel (x-NBA) catalysts with different boron/nickel molar ratio (x = 0–1) were prepared by an epoxide-driven sol–gel method. The effect of boron/nickel molar ratio on the catalytic activities and physicochemical properties of nickel–boron–alumina xerogel catalysts was investigated in the steam reforming of liquefied natural gas (LNG). All the mesoporous x-NBA catalysts showed similar surface area. Introduction of boron increased interaction between nickel and support. In addition, introduction of boron into x-NBA catalysts reduced methane activation energy and increased nickel surface area. Promotion of boron had a positive effect on the catalytic activity due to the increase of adsorbed methane and nickel surface area. The amount of adsorbed methane and nickel surface area exhibited volcano-shaped trends with respect to boron/nickel molar ratio. LNG conversion and hydrogen yield increased with increasing the amount of adsorbed methane and with increasing nickel surface area. Among the catalysts, 0.3-NBA, which retained the largest amount of adsorbed methane and the highest nickel surface area, showed the best catalytic performance. It was also revealed that x-NBA catalysts showed strong coke resistance during the steam reforming reaction.     

The dispersed SiO2 microspheres supported Ru catalyst with enhanced activity for ammonia decomposition

Ru nanoparticles supported on SiO₂ microspheres (Ru/SiO₂-GUS) were prepared by the glucose-urea-metallic salt method and applied in the decomposition of ammonia. In the glucose-urea-metallic salt method, glucose as the carbon template plays a significant role in the formation of diffusion-beneficial structural properties of Ru/SiO₂-GUS, and also induceds the modification of the electronic state of Ru. Ru/SiO₂-GUS exhibited higher catalytic activity compared with the catalyst prepared with the impregnation method. The catalytic performance of Ru/SiO₂-GUS was further enhanced with the addition of either K or Cs——the addition order and amount strongly affecting the catalytic performance. When the ratio of K/Cs to Ru is 2, the alkali metal (KOH/CsOH) solution is added in the homogeneous solution of glucose, urea, RuCl₃ and the colloidal silica, the promotion effect of K/Cs is the strongest, particularly under lower reaction temperatures. However, the promotion effects of K and Cs are different as reveled by the combined results of H₂-TPR, XPS and NH₃-TPSR. More NH₃ can be absorbed on K–Ru/SiO₂-GUS and the electron density of Ru decreased. By contrast, more metallic Ru formed on Cs–Ru/SiO₂-GUS, facilitating N₂ recombination.     

Assessment of energy-saving technologies retrofitted to existing public buildings in China

This study compared and analyzed both the energy savings and cost-effectiveness of various energy-saving technologies retrofitted to common buildings in China. Base models for an office and store building, set in representative climate zones of China—Beijing, Shanghai, and Guangzhou—were established and calibrated in EnergyPlus, a building energy simulation software program. Various energy-saving technologies were then applied to these models in EnergyPlus to calculate the overall energy savings under different climate conditions. In addition, a payback analysis was performed to determine the cost-effectiveness of each technology. The final results of this study can serve as a preliminary reference for selecting effective and economical energy-saving technologies to retrofit existing public buildings.     

Conductive adhesive with transient liquid‐phase sintering technology for high‐power device applications

A highly reliable conductive adhesive obtained by transient liquid‐phase sintering (TLPS) technologies is studied for use in high‐power device packaging. TLPS involves the low‐temperature reaction of a low‐melting metal or alloy with a high‐melting metal or alloy to form a reacted metal matrix. For a TLPS material (consisting of Ag‐coated Cu, a Sn96.5‐Ag3.0‐Cu0.5 solder, and a volatile fluxing resin) used herein, the melting temperature of the metal matrix exceeds the bonding temperature. After bonding of the TLPS material, a unique melting peak of TLPS is observed at 356 °C, consistent with the transient behavior of Ag₃Sn + Cu₆Sn₅ → liquid + Cu₃Sn reported by the National Institute of Standards and Technology. The TLPS material shows superior thermal conductivity as compared with other commercially available Ag pastes under the same specimen preparation conditions. In conclusion, the TLPS material can be a promising candidate for a highly reliable conductive adhesive in power device packaging because remelting of the SAC305 solder, which is widely used in conventional power modules, is not observed.     

Hypoxia Suppresses Spontaneous Mineralization and Osteogenic Differentiation of Mesenchymal Stem Cells via IGFBP3 Up-Regulation

Hypoxia has diverse stimulatory effects on human adipose-derived stem cells (ASCs). In the present study, we investigated whether hypoxic culture conditions (2% O₂) suppress spontaneous mineralization and osteogenic differentiation of ASCs. We also investigated signaling pathways and molecular mechanisms involved in this process. We found that hypoxia suppressed spontaneous mineralization and osteogenic differentiation of ASCs, and up-regulated mRNA and protein expression of Insulin-like growth factor binding proteins (IGFBPs) in ASCs. Although treatment with recombinant IGFBPs did not affect osteogenic differentiation of ASCs, siRNA-mediated inhibition of IGFBP3 attenuated hypoxia-suppressed osteogenic differentiation of ASCs. In contrast, overexpression of IGFBP3 via lentiviral vectors inhibited ASC osteogenic differentiation. These results indicate that hypoxia suppresses spontaneous mineralization and osteogenic differentiation of ASCs via intracellular IGFBP3 up-regulation. We determined that reactive oxygen species (ROS) generation followed by activation of the MAPK and PI3K/Akt pathways play pivotal roles in IGFBP3 expression under hypoxia. For example, ROS scavengers and inhibitors for MAPK and PI3K/Akt pathways attenuated the hypoxia-induced IGFBP3 expression. Inhibition of Elk1 and NF-κB through siRNA transfection also led to down-regulation of IGFBP3 mRNA expression. We next addressed the proliferative potential of ASCs with overexpressed IGFBP3, but IGFBP3 overexpression reduced the proliferation of ASCs. In addition, hypoxia reduced the osteogenic differentiation of bone marrow-derived clonal mesenchymal stem cells. Collectively, our results indicate that hypoxia suppresses the osteogenic differentiation of mesenchymal stem cells via IGFBP3 up-regulation.