超疏水微纳多级表面的可控制造及其俘能应用

超疏水表面在防污减阻、油水分离、生物医用等领域应用广泛,在摩擦发电蓝色能源收集领域展现出新的应用前景,但其大面积制造及结构形貌的精确调控仍充满挑战。提出光刻和模塑成形相结合的微纳多级表面的可控制造工艺,分别以光刻工艺制造的微米孔和V形孔阳极氧化铝纳米孔为微米尺度和纳米尺度模板,采用一步模塑成形工艺实现微纳多级表面的构建,并通过改变模板尺寸简易并精确调控微纳多级表面的形貌和结构尺寸。通过接触角测量仪分析发现,相比单级纳米表面和单级微米表面,构建的微纳多级表面疏水性能显著提升,并实现超疏水,静态接触角最高达158°,滚动角仅为2°。最后开展超疏水微纳多级表面在水能收集方面的应用研究,采用搭建的固-液摩擦纳米发电测试装置分析表面结构对摩擦电输出性能的影响。结果表明:相比平膜和单级微米表面,微纳多级表面由于摩擦面面积增加和疏水性能增强产生更加优异的电输出信号。当水流速度为8 mL/s时,微纳多级表面的输出电压峰值最高为46 V,短路电流峰值最高为6.3μA。提出了一步模塑成形工艺,实现了超疏水微纳多级表面的大面积、可调控制造,基于微纳多级表面构建的固-液摩擦纳米发电机有望应用于水能收集、自驱动传感等领域。

基于管状结构的液–固接触摩擦纳米发电机

构建微能量收集系统并将其作为传感器分布式电源或自驱动传感器具有重要意义。基于摩擦起电原理,设计并制作一种管状结构的单电极液-固接触摩擦纳米发电机(liquid-solid triboelectric nanogenerator,LS-TENG),实现对固–液摩擦过程所产生电荷的直接提取,无需传统摩擦纳米发电机的静电感应过程。首先,基于多物理场耦合分析液-固接触摩擦纳米发电机工作原理,解析电荷转移过程中的电势分布。其次,试验探究液体流量、管道长度、内径和材料对摩擦纳米发电机输出特性的影响情况。最后展示所构建的摩擦纳米发电机作为微电源的负载供能特性。研究发现,LS-TENG的输出电压、电流、转移电荷与流量成正比,与管道内径成反比;LS-TENG输出电能经过整流桥可实现对电容充电储能,在610 mL·min-1的流量下可驱动至少40个LED灯珠。相关研究成果为构建基于管状结构的微水能收集系统提供参考。

Energy-Efficient Mobile Data Collection Adopting Node Cooperation in an Underwater Acoustic Sensor Network

This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node individually employing traditional automatic-repeat-request(ARQ) protocol.We propose a practical node cooperation(NC) protocol to enhance the collection efficiency,utilizing the fact that underwater nodes can overhear the transmission of others.To reduce the source level of underwater nodes,the underwater data collection area is divided into several sub-zones,and in each sub-zone,the mobile surface node adopting the NC protocol could switch adaptively between selective relay cooperation(SRC) and dynamic network coded cooperation(DNC) .The difference of SRC and DNC lies in whether or not the selected relay node combines the local data and the data overheard from undecoded node(s) to form network coded packets in the retransmission phase.The NC protocol could also be applied across the sub-zones due to the wiretap property.In addition,we investigate the effects of different mobile collection paths,collection area division and cooperative zone design for energy saving.The numerical results showthat the proposed NC protocol can effectively save energy compared with the traditional ARQ scheme.

Influence of Temperature, Water Quality and Collector Type on Flotation Performance of a Peruvian Phosphate Ore

The sedimentary phosphate deposit of Bayovar is located in a very dry area of Peru （desert of Sechura） which is close to the Pacific coast. It consists of seven superposed layers （beds） which call for different strategy of concentration. The ore is composed predominantly by apatite （84% in weight basis） plus silicates （16%）. To concentrate phosphate from beds 6-7, it is necessary to carry out further cationic reverse flotation of silicates, at neutral pH, to yield a concentrate which meets market specification. The new process was developed in laboratory scale by a collaborative program conducted between Vale S. A. and the University of Sao Paulo--Brazil. As water resources are very limited at Bayovar region, all the steps of concentration, including flotation, must be performed with seawater which must be continuously recycled. This work addresses some relevant topics related to the use of seawater in the reverse cationic flotation of silicates： influence of temperature, water quality （ageing and chemical composition） and collector type. The results indicate that amido amine works better than ether amine. If flotation is conducted with the former collector, the separation process is able to tolerate changes in temperature （25 ℃-40 ℃） and water quality caused by either evaporation or ageing.

The Impacts of Co-creation of Local Culture English Books on EFL 5th Graders＇ English Vocabulary Ability and Local Cultural Knowledge

The purpose of this study aims to explore the impacts of task-based co-creation of local picture books on facilitating the development of vocabulary ability and cultural knowledge ofEFL 5th graders with different English proficiency levels in Taiwan. Twenty-one 5th graders participated in this study forty minutes per week, lasting for sixteen weeks. They were required to co-create English picture books of Pinghu through thematic task-based activities. Research data required for the study were collected through the pre-/post-tests of vocabulary and cultural knowledge, a participants＇ feedback questionnaire as well as semi-structured interviews. The results of this study showed that after experimental instruction, EFL 5th graders significantly improved their recognition of the connection between English word sounds and word meanings, word meanings and word forms, word forms and word meanings, as well as spellings. Moreover, their local cultural knowledge was improved significantly as well. Furthermore, based upon the 5th graders＇ responses to questionnaire and semi-structure interview, most of them developed a very positive attitude towards the activities of co-creating local picture books and their interest, self-confidence in English writing, and English learning behavior. Based on the findings, some suggestions were offered for the pedagogical applications and future studies.