Influences of the inner diameter of the solid shielding tube on the characteristics of the radio-frequency cold atmospheric plasma jet

Active control of the local environment of the cold atmospheric plasma (CAP) jet is of great importance in actual applications since the CAP operates in an open atmosphere with the inevitable entrainment of the surrounding cold air. In this paper, the solid shielding effects of the cylindrical quartz tubes with different inner diameters on the characteristics of the CAP jets driven by a radio-frequency (RF) power supply are studied experimentally. The experimental results show that the total length of the shielded plasma jet can be increased significantly by an appropriate combination of the quartz tube inner diameter and that of the plasma generator nozzle exit with other parameters being unchanged. This phenomenon may be qualitatively attributed to the loss of diffusion of the charged particles in the radial direction under different inner diameters of the quartz tubes. Compared with the plasma free jet, the plasma shielding jet is produced with optimized parameters including longer plasma jet length, higher concentrations of chemically reactive species, higher rotational, vibrational, and electron excitation temperatures when the inner diameters of the solid shielding tube and the generator nozzle exit are the same. A maximum plasma jet length of 52.0 cm is obtained in contrast to that of 5.0 cm of the plasma free jet in this study. The experimental results indicate that the solid shielding effect provides a new method for the active control of the local environment of the RF-CAP jet operating in an open atmosphere.     

Improved Corrosion Resistance of Selective Laser Melted Ti–5Cu Alloy Using Atomized Ti–5Cu Powder

The different types of metal powder used for selective laser melting(SLM) process would cause distinct corrosion behavior due to the uniformity of the obtained microstructure.The SLM-produced Ti–5Cu alloy using atomized Ti–5Cu metal powder(SLMed Ti–5Cu) in this work reveals a relatively uniform microstructure with overwhelming acicular α/α′ phase and shows great advantages on corrosion resistance compared with the SLM-produced Ti–5Cu alloy using the mixture powder(SLMedM Ti–5Cu).The effect of the micro-galvanic cells decreases due to the undetectable Ti_2Cu phase in the microstructure of the SLMed Ti–5Cu.An apparent passivation behavior was observed for SLMed Ti–5Cu instead of severe pitting phenomenon for the SLMed-M Ti–5Cu.The charge transfer resistance of SLMed Ti–5Cu in this work is 10.09 ± 2.63 MΩ cm~2, which is significantly higher than that of SLMed-M Ti–5Cu(4.76 MΩ cm~2).The above result indicates the atomized Ti–5Cu powder plays an important role in the formation of the uniform microstructure of SLMed product, thereby enhancing its corrosion resistance in Hank's solution at 37 ℃.     

镀铝板用耐高温型无铬钝化结合机理及性能

传统的有机类无铬钝化产品在400 ℃的高温条件下黄变较重,在保持优异的耐高温前提下,同时具有优异的耐蚀性和加工性能,设计了镀铝板使用的无机类加少量有机类的无铬钝化产品。利用电化学工作站、X射线光电子能谱、X射线荧光谱、红外光谱等方法,对该无铬钝化药剂在热镀铝板表面的成膜机理进行了研究,并结合成膜动力学分析,完成了皮膜与铝硅镀层的界面结合机理分析。对膜重、固化温度对镀铝板工艺性能影响进行研究,得出综合性能优异的膜重控制范围为0.8～1.2 g/m2,对应的PMT温度大于80 ℃。所生产的无铬钝化热镀铝板产品耐高温、耐腐蚀和冲压性能优异,400 ℃烘烤2 h后表面色差ΔE＜3,72 h中性盐雾试验未出现锈蚀。     

Natural Silk Film for Magnesium Protection: Hydrophobic/Hydrophilic Interaction and Self‐Healing Effect

Biodegradable implants are required in order to provide successful treatment of injuries. Temporary magnesium‐based implants with particular properties are needed in cases when it is desirable not only to maintain vital activity, but also to initiate the self‐healing process of damaged bones or tissues as well. Unfortunately, the use of magnesium alloys is limited due to the fast biodegradability of the applied material. The aim of this research is to improve the corrosion resistance of magnesium alloys by sonochemical treatment in silk solution followed by additional layer‐by‐layer deposition of natural silk on the magnesium surface. The sonication process is carried out at a frequency of 20 kHz during 5–10 min, while the duration of the silk layer deposition is 15 min. The corrosion behavior of magnesium substrates modified by natural silk layer‐by‐layer assembly is studied. Magnesium substrates sonochemically treated in silk solution demonstrate three times better corrosion resistance compared to control samples sonochemically treated in water. Additional deposition of a silk layer enhances obtained corrosion resistance by 18 times, resulting in a 54‐fold increase overall.     

Factors Affecting Web Disclosure Adoption in the Nonprofit Sector

ABSTRACT

Nonprofit organizations (NPOs) are strategically using their own personal website to present themselves to the public and share information. Despite the potential benefits of enhanced public confidence and trust, reduced operating costs, improved donor decision making, and increased donations, many nonprofit organizations have resisted the adoption of web disclosure. Informed by the literature on information systems (IS) adoption and technological innovation, this study examines the primary factors that influence the adoption and resistance of web disclosure. Our sample consisted of 176 survey responses from an initial group of 3,323 U.S. NPOs. The statistical results indicate that attitude toward disclosure, compatibility of disclosure with current practices, and financial readiness have a positive influence on web disclosure adoption. The findings have implications for research and practice.     

电驱液压式大截面导线压接设备自动化研究

现有的压接设备可控性差、操作复杂,导致压接质量因人而异。针对此问题,提出了基于DDVC技术的导线压接设备自动化控制方案,建立了速度控制系统数学模型,应用Simulink进行仿真,分析系统性能。建立了基于DEFORM的耐张线夹压接实验模型,获得了耐张线夹压接的最佳加载速度曲线,并以此作为压接设备速度控制系统的Simulink仿真模型输入,对压接过程进行了仿真分析。结果表明:开环控制时系统存在一定的超调,加入PID控制后可有效抑制超调;所设计的压接设备可很好地跟随最佳压接曲线,跟随误差仅为0. 904 mm·s-1。研究成果对改进压接设备、提高压接质量提供了新的解决方案。     

热处理对等离子喷涂铁基非晶合金涂层微观结构和耐腐蚀性能的影响

采用等离子喷涂技术在Q235钢基体上制备Fe48Cr15Mo14C15B6Y2非晶合金涂层,之后对涂层进行200,300,500,600,700℃热处理,研究了热处理对涂层微观结构、耐电化学腐蚀性能和耐均匀腐蚀性能的影响。结果表明:随着热处理温度的升高,涂层的非晶含量降低,孔隙率先减小后增大,经300℃热处理后涂层的孔隙率最低,且低于未热处理涂层的;热处理后涂层中的晶体相主要包括α-Fe,Fe-Cr,Fe63Mo37,Fe3C等;随着热处理温度的升高,涂层的自腐蚀电流密度先减小后增大,经300℃热处理后,自腐蚀电流密度最小,涂层的耐电化学腐蚀性能最好;经过热处理后,涂层在NaCl溶液中浸泡31d后的单位面积质量损失减小,且热处理温度越高,单位面积质量损失越小,涂层的耐均匀腐蚀性能提高。     

沿空切顶成巷段巷道围岩变形规律研究

以宏景塔一矿回采工作面为研究对象,基于切顶卸压无煤柱自动成巷技术原理,采用数值模拟计算和现场实测的方法,对该矿成巷段巷道围岩支承压力分布及围岩变形规律进行分析。研究结果表明:随着工作面向前推进,巷道围岩支承压力呈先增大后减小最后趋于稳定的变化趋势,支承压力稳定值为13.5 MPa;受工作面回采动压的影响,距离工作面70 m以内,锚索受力急剧增大到恒阻值、巷道围岩变形明显;距离工作面70~150 m,锚索受力迅速减小、巷道围岩变形逐渐变缓;在距离工作面150 m之后,锚索受力仅有微量变化、巷道围岩变形趋于稳定。因此确定支护体回撤保守安全位置为工作面后方150 m。工程实践表明:所设支护体回撤距离能够应对巷道围岩变形,成巷效果良好。     

淀粉/聚乙烯醇活性包装薄膜及其在食品包装应用中的研究进展

综述了淀粉/聚乙烯醇（PVA）活性包装薄膜及其在食品包装中的研究进展，主要对从不同比例共混、疏水改性、增强改性等方面对淀粉/PVA薄膜的改性研究，从功能特性和活性物质对薄膜性能的影响2个方面对淀粉/PVA活性薄膜研究和薄膜在食品包装中的应用3个方面进行了归纳总结，旨在为以淀粉/PVA为基材的活性包装薄膜研究提供参考。