The electrochemical discharge machining (ECDM) has been proved to be a potential process for the machining of high-strength non-conductive materials. Traveling wire electrochemical discharge machining (TW-ECDM), a newly developed technology, is used to slice the small size (10-30 mm diameter) optical glass and quartz bars. The electrical-thermal etching effect and its feasibility are investigated. The energy release intensities and their physical phenomena under different sizes of discharge wires, power source modulations and methods of electrolyte supply are discussed. The pulsed dc power proves better spark stability and more spark energy release proportion than constant dc power. The input power is modulated to obtain the appropriate frequencies and duty factors for machining glass and quartz materials. The ion translation rate, the electrolyte immersing depth and the concentration of the alkali are found to be the dominant factors of bubbles reaction. Based on the SEM photographs of the workpiece surface, it is noted that the more purple the sparks from the mixed gases of hydrogen and vapor, the better the etching effect is. The V-shape defect occurring at the cut-in and cut-out can be significantly reduced by rotating the workpiece. Finally the appropriate cutting conditions for the quartz and borosilicate optical glass materials are concluded.

Rare cells in the blood often have rich clinical significance. Although their isolation is highly desirable, this goal remains elusive due to their rarity. This paper presents a systemic approach to isolate and characterize trophoblasts from the maternal circulation. A microfluidic rare cell disc assay (RaCDA) was designed to process an extremely large volume of up to 15 mL of blood in 30 min, depleting red blood cells (RBCs) and RBC-bound white blood cells (WBC) while isolating trophoblasts in the collection chip. To minimize cell loss, on-disc labeling of cells with fluorescent immuno-staining identified the trophoblasts. Retrieval of trophoblasts utilized an optimized strategy in which multiple single cells were retrieved within the same micropipette column, with each cell encapsulated in a fluid volume (50 nL) separated by an air pocket (10 nL). Further, whole-genome amplification (WGA) amplified contents from a few retrieved cells, followed by quality control (QC) on the success of WGA via housekeeping genes. For definitive confirmation of trophoblasts, short-tandem repeat (STR) of the WGAamplified content was compared against STR from maternal WBC and amniocytes from amniocentesis. Results showed a mean recovery rate (capture efficiency) of 91.0% for spiked cells with a WBC depletion rate of 99.91%. The retrieval efficiency of single target cells of 100% was achieved for up to four single cells retrieved per micropipette column. Comparison of STR signatures revealed that the RaCDA can retrieve trophoblasts from the maternal circulation.