Organic Thin Film Transistors Fabricated by a Solution Process Using Direct Patterned Single-Layer Graphene Electrodes.

We propose the direct transfer method of single-layer graphene (SLG) from metal catalyst Cu-foil to a polymeric insulator and the direct patterning method of the SLG for electrodes of organic thin-film transistors (OTFTs) without contamination using soft-lithography. Through soft-lithography, SLG can be formed in various patterns relatively easily in comparison with the conventional photolithography method that has multiple complex process steps to make graphene patterns. Furthermore, the 6,13-bis(triisopropylsilylethynyl) pentacene OTFTs are fabricated in solution with SLG source and drain electrodes. As a result, the field-effect mobility of OTFTs based on SLG electrodes was enhanced about 4 times in comparison with that of OTFTs using typical metal electrodes due to the decrease in contact resistance.

Realization of a High Sensitivity Microphone for a Hearing Aid Using a Graphene-PMMA Laminated Diaphragm.

Microphones for hearing aid systems are required to have high sensitivity, an appropriate bandwidth, and a wide dynamic range. In this paper, a high sensitivity microphone, 4 mm in diameter and using a multilayer graphene-PMMA laminated diaphragm that can be applied in hearing aids, is designed, optimized, and implemented. Typically, polyphenylene sulfide (PPS) has been used for the diaphragm of electret condenser microphones (ECM), and this method provides simple, low cost mass production. Generally, the sensitivity of the commercial 4 mm diameter ECM is about -30 to 35 dB (0 dB = 1 V/Pa). A microphone using a nanometer-thick graphene diaphragm has been found to have higher sensitivity than the conventional ECM. However, nanometer-thick multilayer graphene is vulnerable to large mechanical shocks or high sound pressures, and the practical production of nanometer-thick diaphragms also poses a challenge. However, if a multilayer graphene diaphragm of the same thickness as the conventional ECM is used, displacement during diaphragm vibration will be severely attenuated due to the high elastic modulus of graphene, and the microphone sensitivity will be greatly reduced. In this paper, we fabricate a multilayer graphene/poly(methyl methacrylate) (PMMA) laminated diaphragm with sensitivity higher than that of any other microphones currently available for hearing aids, with the appropriate bandwidth in the auditory range. The high sensitivity arises from the laminated structure of the thin graphene membrane with high elastic modulus and from the PMMA membrane with lower elastic modulus and higher dielectric constant. The optimal thickness ratio of the graphene-PMMA layered diaphragm was studied by both analytical and experimental methods, and then a fabricated diaphragm was assembled in a 4 mm diameter microphone package. The performance of the implemented microphone was evaluated, including the sensitivity and total harmonic distortion. It is demonstrated that the microphone using a multilayer graphene-PMMA diaphragm has an excellent sensitivity of -20 dB and a dynamic range of 90 dB, which is on average 9 dB higher than the microphone using the conventional ECM diaphragm.

Rotationally reconfigurable metamaterials based on moiré phenomenon.

Exploiting moiré interference, we make a new type of reconfigurable metamaterials and study their transmission tunability for incident electromagnetic waves. The moiré pattern is formed by overlapping two transparent layers, each of which has a periodic metallic pattern, and the cluster size of the resulting moiré pattern can be varied by changing the relative superposition angle of the two layers. In our reconfigurable metamaterials, both the size and structural shape of the unit cell can be varied simultaneously through moiré interference. We show that the transmission of electromagnetic waves can be controlled from 90% to 10% at 11 GHz by experiments and numerical simulation. The reconfigurable metamaterial proposed here can be applied in bandpass filters and tunable modulation devices.

The association between chronic kidney disease and diabetic retinopathy: the Korea National Health and Nutrition Examination Survey 2008-2010.

PURPOSE: To explore the relationship between chronic kidney disease and diabetic retinopathy in a representative population of Korean diabetic adults. METHODS: We analyzed data from the Korea National Health and Nutrition Examination Surveys (2008-2010). A total of 15,409 individuals (weighted frequency, 32,168,636) aged 19 and over who completed ophthalmologic and renal functional examinations were evaluated. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate of < 60 ml/min/1.73 m2 or proteinuria greater than 1+. Seven standard photographs from the Early Treatment for Diabetic Retinopathy Study were obtained from each eye after pharmacological pupil dilatation. Diabetic retinopathy (DR) was defined as the presence of 1 or more retinal microaneurysms or retinal blot hemorrhages with or without more severe lesions. Vision-threatening diabetic retinopathy (VTDR) was defined as the presence of a clinically significant macular edema (CSME) or proliferative diabetic retinopathy. RESULTS: CKD was significantly associated with DR and VTDR (odds ratio (OR), 95% confidence interval (CI); 2.49(1.43-4.35) and 3.74(1.56-8.95), respectively) in the diabetic population. After controlling for confounders, however, CKD was significantly associated only with DR [adjusted OR (aOR), 95% CI; 2.34(1.04-5.28)]. In the subgroup analysis for CKD, only proteinuria was significantly associated with DR and VTDR (aOR, 95% CI; 4.56(1.51-13.77) and 5.61(1.06-29.87), respectively) in this population. CONCLUSIONS: Our results show that CKD appears to be associated with DR and VTDR in a Korean diabetic population. In particular, proteinuria, not decreased eGFR, is more significantly associated with DR or VTDR.

Long-term trends in intraocular pressure after combined vitrectomy with sub-tenon injection of triamcinolone acetonide.

PURPOSE: To evaluate the long-term effect of vitrectomy by itself and combined vitrectomy with sub-Tenon injection of triamcinolone acetonide (TA) on intraocular pressure (IOP). METHODS: In a retrospective cohort study, the medical records of 56 eyes of 56 patients who underwent nonemergent vitrectomy and were followed up for at least 24 months were reviewed. Thirty-two eyes of 32 patients underwent combined vitrectomy with sub-Tenon injection of TA. Twenty-four eyes of 24 patients underwent vitrectomy only. Increased IOP of >4 mmHg from the baseline, change in IOP from the baseline, and preoperative and postoperative measured IOPs were recorded and compared between the two groups, and with fellow eyes. RESULTS: Minimum follow-up period was 24 months. Except the IOP at postoperative 1 day, there were no significant differences between vitrectomized eyes and nonvitrectomized fellow eyes. There were also no differences between vitrectomized eyes and eyes that underwent combined vitrectomy with sub-Tenon injection of TA. And in the comparison of the vitrectomy-only eye group and the vitrectomy with sub-Tenon TA eye group, there was also no significant difference during the whole follow-up period. CONCLUSION: Vitrectomy by itself or combined vitrectomy with sub-Tenon injection of TA does not seem to increase IOP in the long term.

Resist-free antireflective nanostructured film fabricated by thermal-NIL.

Resist-free antireflective (AR) nanostructured films are directly fabricated on polycarbonate (PC) film using thermal-nanoimprint lithography (T-NIL) and the moth-eye shape of AR nanostructure is elaborately optimized with different oxygen reactive ion etching conditions. Anodic aluminum oxide (AAO) templates are directly used as master molds of T-NIL for preparation of AR nanostructures on PC film without an additional T-NIL resist. AR nanostructures are well arranged with a period of about 200 nm and diameter of about 150 nm, which corresponds to those of the AAO template mold. The moth-eye AR nanostructures exhibit the average reflectance of 2% in wavelength range from 400 to 800 nm. From the results, highly enhanced AR properties with simple direct imprinting on PC film demonstrate the potential for panel application in the field of flat display, touch screen, and solar cells.

Reactive lymphoid hyperplasia of lacrimal canaliculus caused by a silicone plug.

Complications of tumorigenesis by a lacrimal silicone plug are rarely reported and most of them were cases of granuloma due to chronic inflammation. The authors present a case of a 57-year-old healthy woman complaining of lower eyelid swelling and protruding mass from lower punctum who had undergone insertion of a lacrimal silicone plug. Surgical mass resection was performed and initial histopathology revealed lymphoid hyperplasia. Additional immunophenotypic markers CD3, CD20, and BCL2 showed reactive lymphoid hyperplasia. It has a histopathologic significance in that it can mimic lymphoma and should be distinguished from malignancy.

Treatment for trichiasis through a combination of eyelash trephination and electrocautery.

PURPOSE: This article introduces 3-mm-deep eyelash trephination combined with electrocautery as a way to increase the success rate for treatment for trichiasis. METHOD: We have modified surgical instruments, ready-made ophthalmic microtrephine and cautery tip for a 3-mm-deep eyelash trephination and electrocautery. After eyelash trephination with microtrephine, electrocautery was added with a bended cautery tip after embedding in the trephination site. The trephined eyelids were photographed biweekly and checked for recurrence until 8 weeks after operation. RESULT: Eyelash trephination combined with electrocautery was carried out on 20 Korean patients. The number of removed cilia was 109. Of these, the number of successfully removed hair follicles was 89. During 8 weeks, the total recurring rate of eyelash trephination combined with electrocautery was 17%. In the case of hair follicle removal success with electrocautery, the recurring rate was as low as 11%, but in the case of hair follicle removal failure with electrocautery, recurring rate is 45%. We checked the depth of removed eyelash follicles, and the mean depth was 2.03 ± 0.085 mm in this study. No serious complication was found during the period of this study. CONCLUSION: The eyelash trephination combined with electrocautery for trichiasis is a method with a low recurrence rate and few complications.

Clinical features of ocular toxoplasmosis in Korean patients.

We report here the records of 10 consecutive Korean patients (10 eyes) with ocular toxoplasmosis which showed the typical clinical manifestations with seropositivity for Toxoplasma gondii specific IgG antibodies by micro-ELISA between 2006 and 2010. Nine patients were males and 1 was female; their age was 50.5 ± 13.8 years. The most common accompanying signs were vitritis (100%), anterior uveitis (70%), and scattered white deposit (80%). Pre-existing retinochoroidal scar was found in 1 (10%) patient. All patients received antiparasitic chemotherapy and systemic corticosteroid treatment, which resolved the presenting attack and recovered the visual acuity better than initial one in 9 patients and worse in 1. Optic atrophy, cataract, and retinal neovascularization were observed during the follow-up period and recurrence was detected in 3 eyes (30%) 6 to 20 months after the initial attack. In Korea, although rarely detected and reported, ocular toxoplasmosis needs more attention in clinical field of retinal diseases.