This study aims to investigate the interfacial crystallization between glass fiber (GF) and polypropylene (PP) by micro-injection molding. Three different kinds of transcrystallinity (TC) were formed at different conditions by different formation mechanisms. The virgin GF could form the TC by aligning the adjacent molecules to parallel with the GF surface, while the modified GF (M-GF) could induce the TC directly on its surface. Furthermore, the M-GF reduced the number of nano-voids between the GF and iPP, characterized by X-ray scattering technique. When β-nucleation agents (β-NA) were added, a novel net-coating layer was first discovered on the M-GF surface. This structure may be caused by the self-organization of β-NA and leads to some unique intensity streaks in SAXS patterns. Based on the experimental results, a schematic model was proposed.
Ultrasonic vibration-composited electrolysis/electro-discharge machining technology (UE/DM) is effective for machining particulate-reinforced metal matrix composites (MMCs). However, the vibration of the tool or workpiece suitable for holes limits the application of UE/DM. To improve the generating machining efficiency and quality of flat and curved surfaces, in this study, we implemented two-dimensional ultrasonic vibration into UE/DM and constructed a novel method named two-dimensional ultrasonic vibration-composited electrolysis/electro-discharge machining (2UE/DM). The influence of vibration on the performance of 2UE/DM compared to other process technologies was studied, and an orthogonal experiment was designed to optimize the parameters. The results indicated that the materiel remove rate (MRR) mainly increased via voltage and tool vibration. The change current was responsible for the MRR in the process. Spindle speed and workpiece vibration were not dominant factors affecting the MRR; the spindle speed and tool and workpiece vibration, which reduced the height difference between a ridge and crater caused by abrasive grinding, were responsible for surface roughness (Ra) and form precision (δ). Additionally, the optimized parameters of 1000 rpm, 3 V, and 5 um were conducted on MMCs of 40 SiCp/Al and achieved the maximum MRR and minimum Ra and δ of 0.76 mm3/min, 3.35 um, and 5.84%, respectively. This study’s findings provide valuable process parameters for improving machining efficiency and quality for MMCs of 2UE/DM.
Schwannoma rarely occurs in the stomach. We present a case of gastric schwannoma, which was initially evaluated by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy and confirmed by surgical resection. The patient was a 57-yearsold woman with history of dyspepsia, who was found to have a large submucosal mass in the stomach. EUS-FNA showed scant spindle cells with abundant lymphocytes. The spindle cells were immunoreactive with S100, while negative for CD117, desmin, and CD34. The lymphocytes were mixed B-cells and T-cells. Immunostaining, flow cytometry, and molecular testing showed no evidence of B-cell lymphoma. The diagnosis of gastric schwannoma was confirmed by histopathological evaluation of the resected tumor. Gastric schwannoma has unique features of mixed spindle cells and lymphocytes. The tumor should be differentiated from other gastric mesenchymal tumors, and lymphoproliferative disorder is a pitfall. K E Y W O R D S endoscopy, fine needle aspiration, mesenchymal tumor, schwannoma, stomach
According to the machining characteristics of ceramic-particle-reinforced metal matrix composites, an experimental study on difficult-to-machine materials was carried out by two-dimensional (2D) rotatory ultrasonic combined electrolytic generating machining (RUCEGM), which organically combined an ultrasonic effect with a high-speed rotating tool electrode and electrolysis. After building the one-dimensional (1D) and 2D-RUCEGM systems, the factors influencing the combined machining process were analyzed and the experiments on RUCEGM were conducted to explore the feasibility and advantages of 2D-RUCEGM. The experimental results showed that, compared with 1D-RUCEGM, 2D-RUCEGM had higher accuracy, which increased about 21% and also reduced the machining time. Under certain conditions, the efficiency of 2D-RUCEGM was proportional to the voltage, and the machining efficiency could be enhanced by increasing the feed rate. The inter-electrode voltage detection module used in the experiment could improve the machining stability of the system.
Materials such as stainless steel, cemented carbide, metal matrix composites, etc., usually require combinations of multiple machining, due to their high hardness, high wear resistance, and other mechanical properties. Ultrasonic combined electro-machining (UCEM) is the preferred solution for the efficient machining of high hardness and high toughness products. However, the machining can deviate from the expected values for factors such as physical and chemical complexity and variability, as well as tool head wear, which can make it difficult to keep the process stable, thus leading to a decrease in machining efficiency. To address the above problems, this study constructed and optimized a UCEM detection and control system based on an analysis of the mutual coordination mechanism of each effects of combined machining, and proposed a machining short-circuit avoidance method based on inter-pulse voltage detection that can avoid the irreversible harm caused by the high current generated during electrode short-circuiting in electrolytic machining. This method could be of great value and significance in preventing workpiece burns and improving machining quality.
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