RESUMEN
Pseudoangiomatous stromal hyperplasia (PASH) is a rare idiopathic proliferative mesenchymal breast disease related to hormonal imbalance, and thus extremely rare in children and adolescents. In addition, PASH manifests as a bilateral gigantomastia in some cases with no established cause or treatment. Here, we report a case of a rapidly developed PASH presenting with bilateral gigantomastia in a 14-year-old premenarchial female patient. Considering the patient's age and emotions and the need for nipple-areolar complex repositioning, we performed reduction mammoplasty rather than total mastectomy despite the possibility of recurrence. Although some masses could not be completely removed, no complications, such as infection, wound dehiscence, or hematoma occurred postoperatively. The patient was stable during the 18-month follow-up period, although an evidence of recurrent and residual disease was noted upon ultrasonography.
RESUMEN
Recently, as air pollution and particulate matter worsen, the importance of a platform that can monitor the air environment is emerging. Especially, among air pollutants, nitrogen dioxide (NO2) is a toxic gas that can not only generate secondary particulate matter, but can also derive numerous toxic gases. To detect such NO2 gas at low concentration, we fabricated a GNWs/NiO-WO3/GNWs heterostructure-based gas sensor using microwave plasma-enhanced chemical vapor deposition (MPECVD) and sputter, and we confirmed the NO2 detection characteristics between 10 and 50 ppm at room temperature. The morphology and carbon lattice characteristics of the sensing layer were investigated using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. In the gas detection measurement, the resistance negative change according to the NO2 gas concentration was recorded. Moreover, it reacted even at low concentrations such as 5-7 ppm, and showed excellent recovery characteristics of more than 98%. Furthermore, it also showed a change in which the reactivity decreased with respect to humidity of 33% and 66%.
RESUMEN
This research is conducted in order to investigate the structural and electrical characteristics of carbon nanowalls (CNWs) according to the sputtering time of interlayers. The thin films were deposited through RF magnetron sputtering with a 4-inch target (Ni and Ti) on the glass substrates, and the growth times of the deposition were 5, 10, and 30 min. Then, a microwave plasma-enhanced chemical vapor deposition (PECVD) system was used to grow CNWs on the interlayer-coated glass substrates by using a mixture of H2 and CH4 gases. The FE-SEM analysis of the cross-sectional and planar images confirmed that the thickness of interlayers linearly increased according to the deposition time. Furthermore, CNWs grown on the Ni interlayer were taller and denser than those grown on the Ti interlayer. Hall measurement applied to measure sheet resistance and conductivity confirmed that the electrical efficiency improved significantly as the Ni or Ti interlayers were used. Additionally, UV-Vis spectroscopy was also used to analyze the variations in light transmittance; CNWs synthesized on Ni-coated glass have lower average transmittance than those synthesized on Ti-coated glass. Based on this experiment, it was found that the direct growth of CNW was possible on the metal layer and the CNWs synthesized on Ni interlayers showed outstanding structural and electrical characterizations than the remaining interlayer type.
RESUMEN
In this study, the growth characteristics of carbon nanowalls (CNWs), which are applied to many devices because of their high aspect ratio and excellent electrical characteristics thanks to their two-dimensional structure, were confirmed by changing the ratio of methane (CH4) and hydrogen (H2) therein. In many studies, CNWs were grown using various chemical vapor deposition (CVD) or sputtering methods, with a mixture of CH4 and H2 or argon (Ar) gas. To find the suitable rate, 25 sccm CH4, which is used as the source gas, was first injected into the chamber, and the characteristics were confirmed by changing the amount of H2 gas from 0 to 50 sccm. Ultrasonically cleaned Si wafer was used as the substrate, and the CNW was grown for 10 minutes at microwave power (1300 W, 600°C) using microwave-plasma-enhanced CVD (MPECVD).
RESUMEN
Aluminum-doped zinc oxide (AZO) thin films were deposited on glass and polyimide substrates using radio frequency magnetron sputtering. We investigated the effects of the oxygen gas ratio on the properties of the AZO films for Cu(In,Ga)Se2 thin-film solar cell applications. The structural and optical properties of the AZO thin films were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and UV-Visible-NIR spectrophotometry. The oxygen gas ratio played a crucial role in controlling the optical as well as electrical properties of the films. When oxygen gas was added into the film, the surface AZO thin films became smoother and the grains were enlarged while the preferred orientation changed from (0 0 2) to (1 0 0) plane direction of the hexagonal phase. An improvement in the transmittance of the AZO thin films was achieved with the addition of 2.5-% oxygen gas. The electrical resistivity was highly increased even for a small amount of the oxygen gas addition.