This paper presents a new polydimethylsiloxane (PDMS) dry-etching method that uses microwave plasma. The applicability of the method for fabricating microstructures and removing residual PDMS is also verified. The etch rate of PDMS was dominantly influenced by the gas flux ratio of CF 4 /O 2 and the microwave power. While the PDMS etch rate increased as the flux ratio of CF 4 was increased, the etch rate decreased as the flux ratio of O 2 was increased. The maximum etch rate of 4.31 μm min −1 was achieved when mixing oxygen (O 2 ) and tetrafluoromethane (CF 4 ) at a 1:2 ratio at 800 W power. The PDMS etch rate almost linearly increased with the microwave power. The ratio of the vertical etch rate to the lateral etch rate was in a range of 1.14-1.64 and varied with the gas fluxes. In consideration of potential applications of the proposed PDMS etching method, array-type PDMS microwells and network-type microprotrusion structures were fabricated. The contact angle was dramatically increased from 104 • (non-etched PDMS surface) to 148 • (etched PDMS surface) and the surface was thereby modified to be superhydrophobic. In addition, a thin PDMS skin that blocked holes and PDMS residues affixed in nickel microstructures was successively removed.
We present the replication of polyethylene (PE) nano-micro hierarchical structures and their application for superhydrophobic surfaces. A commercial ultrasonic welding system was used to apply ultrasonic vibration energy to the forming of nano-micro hierarchical structures. To evaluate ultrasonic formability, Ni nanomold and nano-micro hierarchical mold were designed and fabricated. The optimal weld times were 1.5 s and 3.0 s for PE nanoprotrusions and nano-micro hierarchical structures, respectively. The forming process was conducted at atmospheric pressure. The PE structures were well replicated without a vacuum. The trapped air in the microcavity of the nano-micromold was dispersed and absorbed into the molten PE. Ultrasonic nano-microreplication technology showed an extremely short processing time and did not require a vacuum environment. To investigate the applicability of ultrasonic forming, the fabricated nanoprotrusions and nano-micro hierarchical structures were coated with plasma polymerized fluorocarbon (PPFC) of a hydrophobic nature and were applied to modify superhydrophobic surfaces. The contact angle was increased from 106 • (smooth surface) to 125 • (nanostructured surface) and finally to 160 • (nano-microstructured surface) so that the surface became superhydrophobic.
This paper presents a novel fabrication method of patternable silicon nanotips. The proposed fabrication method involves four steps: lithography, the first deep reactive ion etching (DRIE), removal of the photoresist and the second DRIE. The fabricated silicon nanotips are well aligned along the edges of microstructures. The plane shape of the microstructure was determined by the patterned shape of the photoresist. It means that the silicon nanotips can be patterned by the patterned shape of the photoresist. The width of the nanotips, 1 µm below the top, was measured to be about 200 nm. The fabricated nanotips were applied to modify the surface of silicon from hydrophilic to superhydrophobic. The contact angle was drastically increased from 79.7 • (bare silicon surface) to 158.3 • (surface modified with nanotips). Therefore, the surface was modified from hydrophilic to superhydrophobic.
Transmesenteric hernias have bimodal distribution and occur in both pediatric and adult patients. In the adult population, the cause is iatrogenic, traumatic, or inflammatory. We report a case of transmesocolic hernia in an elderly person without any preoperative history. An 84-year-old Korean female was admitted with mid-abdominal pain and distension for 1 d. On abdominal computed tomography, we diagnosed transmesocolic hernia with strangulated small bowel obstruction, and performed emergency surgery. The postoperative period was uneventful and she was discharged 11 d after surgery. Hence, it is important to consider the possibility of transmesocolic hernia in elderly patients with signs and symptoms of intestinal obstruction, even in cases with no previous surgery.
Tuberculosis of the sigmoid colon is a rare disorder. An 80-year-old man visited Bongseng Memorial Hospital for medical examination. A colonoscopy was performed, and a lesion in the sigmoid colon that was suspected to be colon cancer was found. A biopsy was performed, and tuberculous enteritis with chronic granulomatous inflammation was diagnosed. Intestinal tuberculosis is most frequent in the ileocecal area, followed by the ascending colon, transverse colon, duodenum, stomach, and sigmoid colon, in descending order. Hence, we report a case of intestinal tuberculosis in the sigmoid colon, which is rare and almost indistinguishable from colon cancer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.