3D Printing Conductive Composites with Poly(ionic liquid) as a Noncovalent Intermedia to Fabricate Carbon Circuits

In this study, a kind of imidazole type poly(ionic liquid) ([PEP-MIM]Cl) is synthesized, which can disperse carbon effectively. [PEP-MIM]Cl is used as an intermediate to coat carbon on the poly(acrylic acid)(PAA-co-MBA) via ion exchange to obtain conductive polymer composite (CPC). A series of characterizations are performed. Experiments show that carbon can be coated on the PAA-co-MBA uniformly, and compared with using carbon as filler, this method requires less carbon to achieve good conductive performance. The carbon layer on the polymer's surface is enriched via the swelling-shrinking properties of PAA-co-MBA according to the SEM images. Furthermore, in combination with 3D printing technology, PAA-co-MBA can be designed into different shapes to achieve various functions such as pressure-sensing element. Finally, a new type of CPC named carbon clad polymeric laminate (CCPL) is prepared by using the carbon coating method and 3D printing technology. It has the potential to replace copper clad laminate (CCL) and printed circuit board (PCB), to a certain extent. This technology expands the preparation method and application of the CPC such as flexible and wearable conductive fabrics.     

The Effects of Phenyltrimethoxysilane Coupling Agents on the Properties of PTFE/Silica Composites

A study on PTFE reinforced with SiO₂ was described. This study included the manufactural process of SiO₂-reinforced PTFE and the effects of the content of silane (Z6124) on the properties of the composites material, such as thermal, dielectric properties, tensile strength and morphology, etc. PTFE/silica composites of 60 wt% SiO₂ loaded with a different coupling agent content were mixed by a high-speed dispersion machine and prepared by a two-roll milling machine. Our results show that the sample treated with 3 wt% silane has the highest tensile strength and optimum dielectric properties. Furthermore, the tensile strength and coefficient of thermal expansion (CTE) increase, and the water absorption decreases, with an increasing silane content. These experiments reveal that silane treatment can reduce the overall hydrophilicity of the composites. Finally, predictions on dielectric and CTE properties are discussed. It has been found that experimental values of the dielectric constant agree well with those predicted by the rule of mixture.     

积极引导新社会阶层有序参政议政的思考

改革开放30年来中国社会结构发生的最大变化是新社会阶层的形成。随着社会主义市场经济体制的初步建立,新社会阶层的队伍不断壮大,使中国经济、社会的影响力也越来越大,并在政治舞台上渐渐有了一席之地。人们参政愿望的强烈、自身素质的提高以及参政过程中存在的不同程度的问题,为新社会阶层有序参政提供了可能性和必要性,而执政党的积极引导则成为新社会阶层有序参政议政的领路航标。     

NH_3-(NH_4)_2SO_4体系浸析PCB污泥中铜的研究

利用NH3-(NH4)2SO4体系,对印刷电路板(printed circuit boards,PCB)生产过程中产生大量的含铜污泥中的铜进行浸析。对PCB污泥中重金属的质量分数进行了测定,其中铜在污泥中的质量分数为33.500%,其余金属质量分数较小。重点探讨了氨-硫酸铵浓度及pH、浸析时间、液固比、温度等条件对浸析率的影响。NH3-(NH4)2SO4体系对PCB污泥中铜浸析的最优条件为氨、硫酸铵浓度分别为3.0mol/L和1.5mol/L,液固比为20mL/g,浸析时间为180min,浸析温度为25℃。在最优条件下进行了浸析应用试验,结果表明铜的浸析率可达到97.5%,此方法的相对标准偏差(relative standard deviation,RSD)为0.63%。     

Using Courseware Discussion Boards to Engage Graduate Students in Online Library Workshops

ABSTRACT

Librarians at Oregon State University (OSU) Libraries used the discussion board features of Blackboard courseware to create an interactive experience for graduate students at a distance who could not attend the on-campus “Literature Review Workshops.” These recently developed workshops have been extremely popular with graduate students across the disciplines and have generated a growing demand from distance education graduate students and faculty to offer similar information online. Reluctant to simply deliver content via an online tutorial, librarians sought to duplicate the workshop atmosphere by making the sessions available for a short time-period online, asking participants to respond to discussion questions at specific points in the workshop, and offering audio-mediated online demonstrations of tools and resources. Student feedback and follow-up requests for more workshops support the perception that this approach offered a rewarding learning experience that addressed their specific adult learning needs.     

微机原理与接口课程教学改革探讨

本文针对目前微机原理与接口课程在高职院校教学中存在的一些问题,对课程的教学设计、实践教学及考核形式等方面提出了一系列的改革与措施。     

Home-based communication system for older adults and their remote family

As in many Latin–American countries, in Mexico many older adults live alone as a result of the migration of one or more of their relatives, mostly to the USA. Thus, not only do they live alone, but they might seldom see these relatives for long periods, even though they often depend on them financially. With the goal of designing appropriate communication technology for seniors and their relatives experiencing this situation, we conducted interviews and evaluated scenarios and prototypes to reveal the practical ways they maintain emotional ties despite the distance. Based on those findings, we envisioned a communication system through which seniors and their relatives can maintain close social ties by sharing information, personal reminiscences and stories. We found that older adults perceived the system as a richer, natural form of communication with their relatives that could facilitate their integration into the networks that currently connect members of their families.     

Preferred VDT workstation settings, body posture and physical impairments

In a field study an adjustable VDT workstation was given to each of the 68 operators for one week. The preferred settings, the body postures and subjective evaluations were assessed during normal working activities of the operators. The preferred ranges disclose the following figures: keyboard height (home row above floor) 71-87 cm, screen height (centre above floor) 92-116 cm, viewing angles (eye to screen centre) + 2 to -26 degrees, visual distance (eye to screen) 61-93 cm. There was practically no correlation between preferred settings and anthropometric data of body length or eye levels above floor. The study of body postures revealed that the great majority of operators tend to lean backwards with trunk inclinations between 97 degrees and 121 degrees (95% confidence interval). Some of the preferred settings strongly differ from those recommended in many brochures and standards. The physical complaints in the neck-shoulder and back area are diminished with the preferred settings.     

旱情预警几个主要技术问题的探讨

旱灾是我国主要的自然灾害之一。近年来,我国干旱灾害发生频繁,对经济社会造成的影响不断加剧。加强旱情监测,提高旱情综合评判能力,探索旱情预警方法等,显得十分必要和紧迫。目前,我国旱情监测工作相对薄弱,旱情预测预报起步较晚,旱情预警尚处于研究和探索阶段。本文结合吉林省旱情预警模型研究的有关成果,探讨预警指标、预测模型、预警综合指数等主要技术问题的创建思路,为旱情预警系统研究提供借鉴和参考作用。     

未拆/已拆电子元器件的废旧印刷线路板浸铜规律对比研究

以未拆和已拆电子元器件的废旧印刷线路板（Waste Printed Circuit Boards,WPCBs）为研究对象,对比研究了其在硝酸中金属铜的浸出规律。研究结果表明：两者铜的浸出率随粒径的增大、时间的延长和固液比的减小而增大,温度对两者的影响都不大。已拆电子元器件的WPCBs的铜浸出率随H2O2和HNO3用量的增大而增大,而后者在实验讨论的范围内,H2O2和HNO3用量对其浸出率无明显影响。对于1 g样品,当未拆电子元器件的WPCBs粒径为0.25～0.5 mm,固液比为1：1,H2O2和HNO3均为2 mL时,50℃浸出2 h,即可浸出几乎全部的铜;当已拆电子元器件的WPCBs粒径为0.1～0.25 mm,固液比为1：1,H2O2和HNO3用量分别为2 mL和6 mL时,室温浸出2 h,铜浸出率达92.03%。