Hyun Jin Lee

Periodic Array of Polyelectrolyte-Gated Organic Transistors from Electrospun Poly(3-hexylthiophene) Nanofibers

High-performance organic field-effect transistors (OFETs) based on polyelectrolyte gate dielectric and electrospun poly(3-hexylthiophene) (P3HT) nanofibers were fabricated on a flexible polymer substrate. The use of UV-crosslinked hydrogel including ionic liquids for the insulating layer enabled fast and large-area fabrication of transistor arrays. The P3HT nanofibers were directly deposited on the methacrylated polymer substrate. During UV irradiation through a patterned mask, the methacrylate groups formed covalent bonds with the patterned polyelectrolyte dielectric layer, which provides mechanical stability to the devices. The OFETs operate at voltages of less than 2 V. The average field-effect mobility and on/off ratio were approximately 2 cm(2)/(Vs) and 10(5), respectively.

Clinical efficacy of initial intratympanic steroid treatment on sudden sensorineural hearing loss with diabetes

Objective: The purpose of this study is to compare the efficacy of intratympanic steroid injection (ITSI) with that of systemic steroids as an initial treatment of sudden sensorineural hearing loss (SNHL) with diabetes. Study Design: Prospective, nonrandomized multicenter clinical trial. Setting: Multicenter study in Busan and Masan, South Korea. Subjects and Methods: A total of 114 sudden SNHL patients who were diagnosed with diabetes were divided into peroral (PO) group (n = 48), intravenous (IV) group (n = 32), and intratympanic (IT) group (n = 34). In the PO group, prednisolone was used orally for 10 days, per schedule. In the IV group, prednisolone was administered intravenously for seven days, followed by oral administration of tapered doses for another several days. In the IT group, dexamethasone was injected into the tympanic cavity four times within a two-week period. Hearing outcome was assessed before and after the treatment. Results: All groups showed significant improvement with criteria of 15 dB (P < 0.05). However, there was no significant difference in hearing gain and recovery rate among groups (P > 0.05). Systemic steroid treatment was stopped for two patients in the IV group and for one in the PO group due to uncontrolled hyperglycemia. However, in the IT group, there were no patients who failed to control their blood sugar level. Conclusion: ITSI is as effective as systemic steroid treatment for sudden SNHL patients with diabetes and it can avoid undesirable side effects. Therefore, we consider ITSI to be a more reasonable alternative as an initial treatment for sudden SNHL patients with diabetes.

Broadband planar antenna having round corner rectangular wide slot

A round corner rectangular wide slot antenna is proposed with a novel feeding geometry to have better wideband characteristics than a normal rectangular wide slot antenna. The input impedances of slots with various geometries were calculated and the antenna having the best result was fabricated for verification. The measured bandwidth of the antenna is almost two octaves (2.08 GHz to 8.25 GHz) with VSWR<2.

Autoimmunity as a Candidate for the Etiopathogenesis of Meniere's Disease: Detection of Autoimmune Reactions and Diagnostic Biomarker Candidate

Menieres disease is an inner ear disorder that can manifest as fluctuating vertigo, sensorineural hearing loss, tinnitus, and aural fullness. However, the pathologic mechanism of Menieres disease is still unclear. In this study, we evaluated autoimmunity as a potential cause of Menieres disease. In addition we tried to find useful biomarker candidates for diagnosis. We investigated the protein composition of human inner ear fluid using liquid column mass spectrometry, the autoimmune reaction between circulating autoantibodies in patient serum and multiple antigens using the Protoarray system, the immune reaction between patient serum and mouse inner ear tissues using western blot analysis. Nine proteins, including immunoglobulin and its variants and interferon regulatory factor 7, were found only in the inner ear fluid of patients with Menieres disease. Enhanced immune reactions with 18 candidate antigens were detected in patients with Menieres disease in Protoarray analysis; levels of 8 of these antigens were more than 10-fold higher in patients than in controls. Antigen-antibody reactions between mouse inner ear proteins with molecular weights of 23–48 kDa and 63–75 kDa and patient sera were detected in 8 patients. These findings suggest that autoimmunity could be one of the pathologic mechanisms behind Menieres disease. Multiple autoantibodies and antigens may be involved in the autoimmune reaction. Specific antigens that caused immune reactions with patients serum in Protoarray analysis can be candidates for the diagnostic biomarkers of Menieres disease.

Transoral robotic surgery for neurogenic tumors of the prestyloid parapharyngeal space

The parapharyngeal space is a difficult area for a surgical approach due to anatomical complexity. We performed a minimally invasive and precise surgical technique to remove neurogenic tumors of the prestyloid parapharyngeal space using transoral robotic instrumentation. The mass was successfully removed in the two cases with three-dimensional visualization providing an excellent view of the resection margin and the dissection plane preserving the vital structures. An adequate resection margin was acquired, and no violation of the tumor capsule occurred. No significant complications were noted. Transoral robotic surgery was feasible for neurogenic tumors of the prestyloid parapharyngeal space, providing a sufficient resection margin and delicate dissection through excellent surgical views and instrumentation.

Valence and spin states in delafossite AgNiO2 and the frustrated Jahn-Teller system ANiO2 "A=Li,Na…

Electronic structures of delafossite oxides AgNi1�xCoxO2 and the frustrated Jahn-Teller JT system ANiO2 A =L i,N a have been investigated by employing soft x-ray absorption spectroscopy and photoemission spectroscopy PES. It is found that Ni ions are in the Ni 2+ -Ni 3+ mixed-valent states and that the low-spin LS Ni 3+ component increases from LiNiO2 to AgNiO2 and NaNiO2, in agreement with the presence of the JT transition in NaNiO2 and the absence of the JT transition in LiNiO2 and AgNiO2 .I n AgNi 1�xCoxO2, the Ni 3+ component increases with x, while Co ions are in the LS Co 3+ states for all x, which is consistent with the metallic nature for low values of x. A good agreement is found between the measured PES spectra and the calculated local spin density approximation LSDA electronic structures of AgNiO2 and AgCoO2, but the pseudogap feature in PES of AgNiO2 is not described by the LSDA.

Endoscopic axillo-breast approach for benign neck mass excision†

Benign neck masses are usually found in younger patients, who are more likely to be concerned about postoperative scars. Until recently, a direct approach through a transcervical incision along the mass has been accepted as a standard surgical procedure for the benign neck mass. However, this conventional transcervical approach leaves a visible scar on the neck, regardless of the size of the incision. We assumed that an endoscopic gasless axillo‐breast (A‐B) approach might be a good alternative method for excision of benign neck masses. The aim of this study was to determine the safety and feasibility of a gasless A‐B approach for the excision of benign neck masses by comparing it to the conventional open approach.

Heat-Flux Analysis of Solar Furnace Using the Monte Carlo Ray-Tracing Method

An understanding of the concentrated solar flux is critical for the analysis and design of solar-energy-utilization systems. The current work focuses on the development of an algorithm that uses the Monte Carlo ray-tracing method with excellent flexibility and expandability; this method considers both solar limb darkening and the surface slope error of reflectors, thereby analyzing the solar flux. A comparison of the modeling results with measurements at the solar furnace in Korea Institute of Energy Research (KIER) show good agreement within a measurement uncertainty of 10%. The model evaluates the concentration performance of the KIER solar furnace with a tracking accuracy of 2 mrad and a maximum attainable concentration ratio of 4400 sun. Flux variations according to measurement position and flux distributions depending on acceptance angles provide detailed information for the design of chemical reactors or secondary concentrators.

Prevalence and clinical significance of spontaneous low-frequency air-bone gaps in Ménière's disease.

Objectives The prevalence and clinical significance of spontaneous low-frequency air-bone gaps (LFABGs) in Ménière’s disease were investigated. Study Design A retrospective study. Settings Tertiary referral center. Patients Three hundred thirty-seven patients with definite Ménière’s disease. Main Outcome Measures The prevalence of LFABG in this population was calculated, and the following parameters were analyzed: 1) changes in hearing thresholds after the resolution of LFABG; 2) correlation between LFABG and electrocochleography (ECoG) results; 3) changes in the number of vertigo spells after the resolution of LFABG; 4) correlation between LFABG and canal paresis (CP) values in caloric testing; and 5) the difference in the prognoses of patients with and without LFABG. Results The prevalence of LFABG was 13.9%. Patients’ hearing thresholds were significantly decreased after the resolution of LFABG (from 49.4 ± 16.8 to 38.3 ± 19.3, p = 0.044), whereas the summating potential and action potential ratio in ECoG tended to increase as LFABG increased (R2 = 0.09, p = 0.03). The mean number of vertigo spells was significantly reduced after the resolution of LFABG (from 2.9 to 0.5, p < 0.0001), but CP did not correlate with LFABG. The prognosis was not different for patients with and without LFABG. Conclusion The number of vertigo spells and hearing thresholds were significantly higher during the period of LFABG development. Although the prognostic importance of LFABG was not significant, it likely reflects the aggravation of the endolymphatic hydrops in the cochlear and vestibular compartments and may be useful for evaluating and treating patients with Ménière’s disease.

Use of Pulsed Dye Laser in the Treatment of Sulcus Vocalis

Objective The pulsed dye laser (PDL) has been shown to be effective in the treatment of hypertrophic scars and keloids in dermatology. On the basis of histopathologic similarities between sulcus vocalis and scar tissue and numerous reports on the treatment of laryngeal lesions, especially scar tissue, with PDL, we evaluated the efficacy of treating sulcus vocalis with PDL. We named this surgical procedure PDL glottoplasty. Study Design Case series with planned data collection. Setting A university-based, tertiary care medical center. Subjects and Methods This study was conducted on 25 patients diagnosed with sulcus vocalis by videostroboscopy at the Gangnam Severance Hospital Otorhinolaryngology Department between August 2006 and February 2012. Energy delivery was fixed at 0.75 Joules (J) per pulse, and each vocal fold was administered 60 to 110 pulses (average 72.5 pulses) during each procedure. Aerodynamic, stroboscopic, and acoustic voice analyses were performed pre- and postoperatively. Results Although assessment was necessarily subjective, our study indicated that vocal folds showed decreased stiffness and improved mucosal wave properties after treatment, resulting in improved vibration and dysphonia. In the objective assessments, most patients who underwent PDL glottoplasty showed improvement in several postoperative voice analysis indices. The differences between preoperative and some postoperative voice parameter indices were statistically significant. Conclusion We found PDL glottoplasty to be beneficial in the treatment of sulcus vocalis. Objective measurements of voice quality and normalization of vocal fold vibration improved after PDL treatment in most cases. Our results warrant further studies with larger numbers of participants and longer follow-up periods.