空气氧化—氨浸出废旧电路板中的铜

提出了在氨水—硫酸铵体系下鼓入空气浸出废旧电路板中铜的新工艺。考察了氨水浓度、硫酸铵浓度、固液比、反应温度、通入空气流量和浸出时间对铜浸出率的影响。结果表明,在下述最佳浸出条件下,渣计铜浸出率达到96.67%:氨水浓度2mol/L,硫酸铵浓度2mol/L,固液比1∶20,反应温度25℃、通入空气量8m3/h、浸出时间4h。     

An inspection and classification method for chip solder joints using color grads and Boolean rules

In order to improve the comprehensive performance of solder joints inspection in three aspects, i.e. high recognition rate, detailed classification of defect types and fast inspection speed, a new detection and classification algorithm of the chip solder joints based on color grads and Boolean rules is developed in this paper. Firstly, the region features, evaluation features and color grads’ features are defined and extracted based on the special solder joint image, which is acquired by a particular image acquisition system composed of a 3-CCD color digital camera and a 3-color (red, green, and blue) hemispherical LED array illumination. Secondly, the models of solder joint types are built based on extracted features and statistical characteristics of solder joint types. Thirdly, the detection and classification method is designed and presented using Boolean rules, then eight common solder joint types, including the acceptable solder joint, pseudo, no solder, lacked solder, excess solder, shifted, tombstone, and miss component, can be classified and detected by the proposed algorithm. Fourthly, the proposed algorithm is optimized to improve the inspection speed based on a parallel computing method. Finally, to evaluate the performance of the proposed method, 79 pieces of PCBs with defects were inspected by the commercial AOI system developed by the authors which integrates the proposed algorithm. Experiment and result analysis illustrates that the proposed method is better than other methods in three aspects, it can detect and classify properly all the eight common types of solder joints, its detailed classification, and high correct rate, which is up to 97.7%, are more useful to the quality control in the manufacturing process, and its inspection speed is faster, thus helping us to improve the efficiency of the manufacturing process.     

Tantalum Capacitor Separation from Waste Printed Circuit Boards with Molten Salt or Metal

Tantalum is the crucial metal of surface-mounted (SMD) tantalum capacitors. Some 50 % of the tantalum mined is consumed in its manufacture, making waste printed circuit boards (WPCBs) an excellent source of secondary tantalum. Yet, its recycling rate is less than 1 %. This paper proposes liberating SMD capacitors from WPCBs by treating them with molten metal or salt. For both processes, the epoxy encapsulation of the capacitors did not disengage from the tantalum core. Furthermore, the molten metal process appears superior to the molten salt one. The tantalum capacitors exit the pyrolysis chamber without salt adhering to them.     

Dual-Wave Acoustofluidic Centrifuge for Ultrafast Concentration of Nanoparticles and Extracellular Vesicles (Small 35/2023)

Extracellular vesicles (EVs) are secreted nanostructures that play various roles in critical cancer processes. They operate as an intercellular communication system, transferring complex sets of biomolecules from cell to cell. The concentration of EVs is difficult to decipher, and there is an unmet technological need for improved (faster, simpler, and gentler) approaches to isolate EVs from complex matrices. Herein, an acoustofluidic concentration of extracellular vesicles (ACEV) is presented, based on a thin-film printed circuit board with interdigital electrodes mounted on a piezoelectric substrate. An angle of 120° is identified between the electrodes and the reference flat of the piezoelectric substrate for simultaneous generation of Rayleigh and shear horizontal waves. The dual waves create a complex acoustic field in a droplet, resulting in effective concentration of nanoparticles and EVs. The ACEV is able to concentrate 20 nm nanospheres within 105 s and four EV dilutions derived from the human prostate cancer (Du145) cell line in approximately 30 s. Cryo-electron microscopy confirmed the preservation of EV integrity. The ACEV device holds great potential to revolutionize investigations of EVs. Its faster, simpler, and gentler approach to EV isolation and concentration can save time and effort in phenotypic and functional studies of EVs.     

参与式课堂教学方法的效果检验——基于“马克思主义基本原理概论”的调查

本文以对马克思主义基本原理概论教学状况的调查为基础,对参与式课堂教学方法及其效果进行了研究。调查表明,参与式课堂教学方法对于活跃课堂气氛、提高教学的针对性与实效性具有非常重要的作用,同时也存在需要改进之处。     

晶振式非接触表面轮廓传感器的动态特性

从理论上对线性伸展模式的石英振子的动态特性进行了分析，讨论了在近场效应作用下，影响晶振品质因数的各种阻尼，并将所获得的解析模型与实验结果进行了比较。     

民族班学生物理化学课程教学方法的探讨

新疆是一个经济、教育欠发达的多民族地区,加强民族学生教育意义重大。物理化学作为一门重要的专业基础课程,如何提高民族班教学质量是常做常新的重要课题。笔者根据多年的教学经验总结了一些民族班物理化学教学的体会和心得,提出了一些探讨性的建议和方法。     

水浸法回收线路板熔炼烟灰焙烧砂有价元素的试验

采用水浸出废旧线路板熔炼烟灰硫酸化焙烧渣,考察浸出温度、搅拌速率、浸出时间和液固比对铜、锌浸出率及铅富集效果的影响。研究表明,较低温度下铜、锌浸出率均可达到99%以上,而铅也能大部分富集在浸出渣中;搅拌速率、浸出时间和液固比对铜、锌浸出率影响较大,对铅浸出率的影响较小。最佳浸出条件为:浸出温度40℃、搅拌速率175r/min,浸出时间1h、液固比5∶1。在此条件下,铜、锌的浸出率分别达到99.49%和99.58%,浸出渣中铅含量达到50%左右。     

从和谐社会·和谐环境所想到的——是创造一个环境,还是培育一个环境

通过和谐社会、和谐环境所想到的几个问题,阐述了笔者对园林事业发展趋势及方向的认识,并通过国内外的最新动态,说明了和谐社会与和谐环境的重要性。并对规划设计在风景园林专业中的位置进行了讨论。最后明确地解释了我们所从事的工作应该是“培育”一个环境而不“是创造”一个环境的理念,并视其为最基本的目标。