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Purpose: We investigated what changes occurred at single hand surgery center during the coronavirus disease 2019 (COVID-19) pandemic in Daegu, Korea using patient data of 4 years (2018–2021).Methods: This is a single-center retrospective study of patients visiting our center during the COVID-19 pandemic (January 22 to May 6, 2020) in comparison to the most recent 4 years from 2018 to 2021. Service volumes (SVs) including the number of in/outpatients, emergency room, elective, and emergency surgeries were analyzed. The demographics, injury mechanism, and place of injury of hand trauma were analyzed in patients seen during the peak period of COVID-19 (February 24 to March 9, 2020) at W Hospital.Results: SVs were significantly reduced in 2020 as compared with other years. The SVs except for the number of emergency surgeries have recovered after 2 months from the first confirmed case of COVID-19 in Daegu, Korea. At the peak period, the effect of COVID-19 was weak on emergency room-related SVs. In addition, a daily number of in/outpatients and elective surgeries had a statistically significant negative correlation with the number of COVID-19 confirmed (p

An epidermoid cyst is a slow-growing benign neoplasm that commonly occurs in the hand. Herein, we report a rare case of an epidermoid cyst with focal neuropathy in the left ring finger of a 38-year-old woman. Preoperatively, the patient complained of erythema, swelling, and paresthesia on her fingertips. On ultrasonography and magnetic resonance imaging, ulnar digital nerve thickening and inflammation around the nerve were observed, and a neurogenic tumor-like schwannoma was expected. An excisional biopsy with neurectomy of the involved sensory branch of the ulnar digital nerve was performed under brachial plexus block. During the operation, there is such an uncommon morphology, yellowish debris under the epineurium of the ulnar digital nerve sensory branch was involved with the epidermoid cyst and seemed to be propagating along the sensory branch from the skin surface. After the operation, the paresthesia and swelling resolved. Over the 6-month follow-up in the outpatient clinic, no complications and recurrences occurred. Thus, we reported a rare intraneural epidermoid cyst (occurred along the digital nerve) in the finger, and we believe that considering the anatomical characteristics and the surrounding structures is important during mass excision.

Purpose: This study evaluated the functional and aesthetic outcomes of a wide-second dorsal metacarpal artery perforator flap for reconstruction of the first web space of the hand. This flap sets the proximal edge of the extensor retinaculum as the distal limit.Methods: We measured the preoperative and postoperative angles of the first web space and assessed the quality of the donor site scar in eight patients.Results: The average flap size was 5.5 × 2.8 cm (range, 5.0 × 1.5 cm to 5.0 × 6.0 cm), and all flaps survived completely. The mean postoperative angle was 53°. The mean Vancouver Scar Scale score of the donor site was 4 points, and the patients had near-normal thickness and vascularity values. There was no distortion of the scar, and patients were satisfied with the scar appearance of the donor site.Conclusion: The wide-second dorsal metacarpal artery perforator flap is a useful technique to reconstruct large defects of the first web space. It is easy to raise, thin, and pliable, and has excellent color and tissue matching.

Background Topical calcineurin inhibitors have been used to treat vitiligo, either alone or in combination with phototherapy; however, the long-term safety of these agents remains controversial. Objective To investigate the risk of lymphoma and skin cancer in vitiligo patients who received topical calcineurin inhibitors or phototherapy. Methods A multicenter retrospective cohort study of 25,694 vitiligo patients who received topical calcineurin inhibitors or phototherapy for 6 weeks or more between 2001 and 2019 was performed. Cumulative doses of topical calcineurin inhibitors and total phototherapy sessions were determined. Outcomes were the development of lymphoma or skin cancer after enrollment, confirmed through chart review and pathology reports. Results During 95,203 person-years, 13 cases of lymphoma, 22 of actinic keratosis, 15 of nonmelanoma skin cancer, and 5 of melanoma were observed. The risk of lymphoma and skin cancer was not significantly increased by topical calcineurin inhibitor dose or phototherapy sessions. The interaction between the topical calcineurin inhibitors and phototherapy was not associated with an increased risk of skin cancer. Limitations Retrospective study, individual follow-up duration less than 4 years, and no adjustment for comorbidities and medication history. Not generalizable to other races. Conclusion The long-term risk of skin cancer or lymphoma was not associated with the use of topical calcineurin inhibitors, phototherapy, and both treatments in combination in patients with vitiligo.

Two advanced, automated crystal orientation mapping techniques suited for nanocrystalline materials—precession electron diffraction (PED) in transmission electron microscopy (TEM) and on-axis transmission Kikuchi diffraction (TKD) in scanning electron microscopy (SEM)—are evaluated by comparing the orientation maps obtained from the identical location on a 30 nm-thick nanocrystalline tungsten (W) thin film. A side-by-side comparison of the orientation maps directly showed that the large-scale orientation features are almost identical. However, there are differences in the fine details, which arise from the fundamentally different nature of the spot pattern and Kikuchi line pattern in terms of the excitation volume and the angular resolution. While TEM-PED is more reliable to characterize grains oriented along low-index zone axes, the high angular resolution of SEM-TKD allows the detection of small misorientation between grains and thus yields better quantification and statistical analysis of grain orientation. Given that both TEM-PED and SEM-TKD orientation mapping techniques are complementary tools for nanocrystalline materials, one can be favorably selected depending on the requirements of the analysis, as they have competitive performance in terms of angular resolution and texture quantification.

Classification of facial and truncal segmental vitiligo and its clinical courses including recurrence rate and patterns: a retrospective review of 956 patients

Vitiligo is a relatively common, acquired hypopigmentary disorder caused by the loss of epidermal melanocytes. It is characterized by asymptomatic, well-circumscribed round to oval-shaped whitish patches that vary in size. Depending on various clinical features, vitiligo is classified into several types, that is, non-segmental, segmental, and undetermined/unclassified vitiligo. The uniform classification of vitiligo is very important in predicting its clinical course and prognosis and communication among researchers. In particular, segmental vitiligo is a highly distinctive subtype of vitiligo considering its clinical features and prognosis. It usually has an onset early in life and spreads rapidly within the affected area limited to one segment of the integument. Signs of vitiligo activity such as Koebnerʼs phenomenon, trichrome vitiligo, inflammatory vitiligo, and confetti-like lesions give useful information to start treatments to block the progression of the disease. Lastly, other hypopigmentary disorders should be distinguished from vitiligo to make the correct diagnosis and prescribe the right treatment. In this report, I review the clinical features of vitiligo, various subtypes according to classification, and the importance for differential diagnosis of hypopigmentary disorders from vitiligo.

Background and objectives The treatment of Riehl's melanosis, also known as pigmented contact dermatitis, is highly challenging. Intense pulsed light (IPL) and 1064 nm Q-switched Nd:Yag (QS-Nd:YAG) laser are reported to have some efficacy. However, no single effective treatment has yet been identified. In this study, we demonstrated the efficacy and safety of the non-ablative 1927 nm fractional thulium fiber laser (TFL, LASEMD™; Lutronic Corp., Goyang, Korea) for patients with Riehl's melanosis. Study design/materials and methods A retrospective chart and photographic review of nine patients with Riehl's melanosis, who had received at least three sessions of TFL treatment, was performed. Before the start of TFL treatment, combination treatment with a topical cream containing hydroquinone, low-fluence QS-Nd:YAG laser, pulsed dye laser, and IPL was used with variable and discouraging effects. Seven patients were treated on the face and two patients on the neck with three to seven sessions at 1-month intervals. Clinical improvement was assessed using clinical photos taken before and after every treatment session according to dermal pigmentation area and severity index (DPASI) and a quartile grading scale by two blinded dermatologists. Results Patients underwent three to seven sessions of TFL treatment depending on severity of pigmentation. Of nine patients, six demonstrated a clinical improvement of 51%-75%, one demonstrated an improvement of 76%-100%, and two showed an improvement of 26%-50% after treatment. The DPASI was significantly decreased from 9.55 to 5.25 on average. Melanin index was decreased after treatment in two patients whose melanin index were measured at initial visits. Treatment-related adverse events, such as scarring or postinflammatory hyperpigmentation (PIH), were not observed in all patients except for transient erythema and swelling. Conclusions This report suggests that TFL could be an alternative and/or additive treatment option for hyperpigmentation in intractable Riehl's melanosis and might be a promising treatment for PIH caused by any reason including Riehl's melanosis. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Background/purpose Vitiligo remains a major challenge in dermatology. However, much of the treatment remains unclear, because little evidence is available. We sought to answer some critical questions pertaining to management of vitiligo patients. Methods A modified Delphi process among 31 vitiligo experts was conducted. A total of 12 clinical vitiligo treatment questions without clear answers were collected via a vote. To address each question, two members performed systematic literature reviews and prepared draft statements along with the levels of evidence and strength of recommendation. After reviewing the draft, all expressed their extent of agreement from 1 (strong disagreement) to 9 (strong agreement) for each item. The drafts were revised to reflect suggested comments. Discussion continued until all members agreed with the ultimate decision. Results The consensus process was completed after five rounds. We identified the best answers to 12 key questions, including issues on long-term phototherapy, systemic and topical corticosteroids, topical calcineurin inhibitors, immunosuppressants, excimer laser treatment, and surgical interventions. Conclusion This consensus would complement current guidelines and aid both physician and patient decision-making in the treatment of vitiligo.

Background Argyria results from silver accumulation in the skin. It is a stressful condition for patients due to skin discoloration. In the past, no effective treatments were available. However, it has been recently reported laser treatments showed promising results. Aim To review and summarize all reported laser treatment options for argyria patients. Methods We reviewed all laser treatment options for argyria in the database of the US National Library of Medicine PubMed. The search of the words "argyria and laser" was performed on the March 4, 2020. Results We found 11 studies that reported laser treatment for argyria. All of the studies were case reports demonstrating treatment responses of laser devices such as 1064 nm Nd:Yag laser and 755 nm alexandrite laser. Despite various treatment parameters, 1064 nm Nd:Yag and alexandrite lasers showed good responses in argyria. However, severe pain during the laser procedure was the main concern. We summarized laser treatment options for argyria including their parameters, treatment response, and anesthesia for laser treatment in argyria. We also report a case of argyria, which successfully responded to low fluence 1064 nm Nd:Yag laser. Conclusion Laser therapies resulted in almost complete clearing of pigment in argyria. Earlier reports showed that 1064 nm Nd:Yag laser successfully treated argyria but recent studies suggested 755 nm alexandrite was also a good treatment option for argyria. Additionally, our case achieved excellent results even in one session of low fluence Q-switched Nd:Yag laser, though we need to ensure pain control during the laser treatment.

The reliability of Ge–Sb–Te phase-change memory (PCM) devices has been limited by failure due to void formation and this still remains one of the critical issues affecting their use in storage-class memory applications. To directly observe the void formation processes in real-time, we implemented in situ switching of PCM devices by applying set and reset voltage pulses to a Ge2Sb2Te5 (GST) cell inside a transmission electron microscope (TEM). The in situ TEM observations directly show that a void nucleates preferentially near the TiN bottom electrode in the GST cell, where the temperature is the highest. The nucleated void grows gradually until it reaches a certain size while migrating slowly toward the positively biased electrode. The fully grown void then continues migrating toward the positively biased electrode in subsequent set pulses. The observed polarity-dependent void migration can be explained by the field-induced redistribution of the constituent elements, especially by the electromigration of under-coordinated Te− ions which have vacancies around them. When the reset pulse with the same voltage polarity is applied, the voids exhibit a slight volume shrinkage but are not completely eliminated, resulting in a reset-stuck failure. The present in situ TEM observations revealing the nucleation, growth, and polarity-dependent migration of voids will contribute to the fundamental understanding of the failure by void formation in nanoscale GST-based PCM devices and help improving the design of reliable PCM devices.

Demands for high-performance displays with high pixel density and picture quality are ever increasing. Indium gallium nitride (InGaN)-based micro-LEDs (μLEDs) are suitable for meeting such demands owing to their high efficiency, brightness, and stability. However, the poor yield of the pick-and-place technique, defect repair, and visibility of edge lines between modules limit the applications of μLEDs. Furthermore, the external quantum efficiency (EQE) decreases (

The International Society for Cutaneous Lymphoma (ISCL) proposes a diagnostic algorithm for early mycosis fungoides (MF) that includes clinical, histological, immunophenotypical, and molecular criteria. Here, we analyzed the immunologic markers and features of T-cell clonality in 38 early MF cases and 22 non-MF cases to validate the ISCL algorithm. We found that CD5 and CD7 expression differed significantly between early MF and non-MF cases, with epidermal discordance of CD7 expression more frequently identified in early MF. Notably, increasing the cut-off value for CD7 expression from 10% to 22.5% improved its sensitivity. Furthermore, TCR-γ and β chain rearrangements were more frequently detected in early MF than in non-MF cases. Based on these findings, we propose CD5 and CD7 deficiency as mandatory immunopathologic criteria and PCR-based testing for TCR-γ and β chains as required molecular/biologic criteria to improve the efficiency of early MF diagnosis using the ISCL algorithm.

Freestanding membranes of electronically reconfigurable complex oxide heterostructure are demonstrated., In recent years, lanthanum aluminate/strontium titanate (LAO/STO) heterointerfaces have been used to create a growing family of nanoelectronic devices based on nanoscale control of LAO/STO metal-to-insulator transition. The properties of these devices are wide-ranging, but they are restricted by nature of the underlying thick STO substrate. Here, single-crystal freestanding membranes based on LAO/STO heterostructures were fabricated, which can be directly integrated with other materials via van der Waals stacking. The key properties of LAO/STO are preserved when LAO/STO membranes are formed. Conductive atomic force microscope lithography is shown to successfully create reversible patterns of nanoscale conducting regions, which survive to millikelvin temperatures. The ability to form reconfigurable conducting nanostructures on LAO/STO membranes opens opportunities to integrate a variety of nanoelectronics with silicon-based architectures and flexible, magnetic, or superconducting materials.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Product sales forecasting is one of the factors that gives significant impact on the company's sales and production plans. In order to increase the accuracy of sales forecast, companies are trying to reflect the opinions of consumers. In this study, we reconfirm the work of Hwang(2017) which analyzed the consumer review by applying the information gain to predict the product sales. This study is meaningful in that it applies the research model to the automobile market, which is one of the traditional durable goods market. Compared to the smartphone market, which has a short product life cycle, the automobile market has well-defined consumers and products are specifically targeted to each consumer group. In this paper, we verify the applicability and predictive power of proposed methodology of Hwang(2017) using actual market data, and show the relationship between information gain from online consumer review and product sales.

Symmetrical giant facial plaque-type juvenile xanthogranuloma (SGFP-JXG) is a rare variant of juvenile xanthogranuloma, reported only in two cases in the literature. We report a case of a 3-year-old Korean boy who developed bilateral yellowish indurated plaques on both cheeks since 1 year after birth. A skin biopsy revealed numerous foam cells and Touton type giant cells throughout the upper dermis, and its immunohistochemical studies resulted positive for CD68 and negative for S-100. The boy was therefore diagnosed as a persistent SGFP-JXG. As the lesion did not show any signs of spontaneous regression, we performed a single session of fractional ablative CO2 laser, which resulted in a significant reduction of the lesion. This is the first case report of a persistent SGFP-JXG on which a single ablative laser therapy was performed with a successful outcome.

Dislocation arrays embedded in low-angle grain-boundaries have emerged as an effective structural defect for a dramatic improvement of thermoelectric performance by reducing thermal conductivity [1]. A transient liquid-flow assisted compacting process has been employed for p-type Bi 0.5 Sb 1.5 Te 3 material to generate the dislocation arrays at grain-boundaries. The details of underlying formation mechanism are crucial for the feasibility of the process on other state-of-the-art thermoelectric materials but have not been well understood. Here, we report the direct observation of dislocation formation process at grain-boundaries of Sb 2 Te 3 system as a proof-of-concept material. We found that the formation of homointerface between Te-terminated Sb 2 Te 3 matrix phase and Te liquid atomic-layer of secondary phase is a prerequisite factor to achieve the low-energy liquid-solid homointerface at compacting elevated temperature. We further demonstrate from the successful observations of atomic structure in the intermediate state of the compacted pellet that the high self-diffusion rate of Te atoms at the liquid-solid homointerface facilitates an effective grain rearrangement, generating low-energy grain-boundaries embedded with dense dislocation arrays. These results pave the way to improve thermoelectric performance of various materials where dislocation arrays are generated by transient liquid-flow assisted compacting process using precursors with an interface constructed with the same types of atoms.

The horizontal wave pressure on the front wall of the caisson protected by armor blocks on the rubble-mounted core is investigated by carrying out physical experiments. There have been few previous studies regarding this type of structure, and the characteristics of horizontal wave pressure on the structure are still unclear. Considering this, a series of experiments were performed by changing the configuration of the coverage rate in front of the caisson and the shoulder width of the armor blocks. For each of the different configurations of the model setup, wave pressure on the caisson was measured under 20 regular waves of different wave periods and heights. By analyzing the obtained experimental data, it was possible to quantify the effects of the coverage rate and the shoulder width on the wave pressure. The wave pressure tended to increase up to maximally 1.5 to 2 times at the exposed part of the caisson if it was incompletely protected. In addition, the wave pressure at the top part of the caisson was substantially reduced with the increase of the shoulder width of the armor layer. Based on these results, adjustment factors for evaluating such effects have been suggested, which can be applicable for the practical design of the caisson covered with armor blocks on the rubble-mounted core.

Background Fractional microneedle radiofrequency (FMR) and nonablative 1927-nm fractional thulium fiber laser (TFL) are widely used for skin rejuvenation treatment. Objectives To investigate the efficacy and safety of combined treatment with both devices for wrinkles. Patients and methods Twenty-five patients with wrinkles were enrolled. One side of the face was treated with FMR alone, while the other side was treated with a combination of FMR and TFL. Each treatment consisted of 3 sessions at four-week intervals and patients were followed up 12 weeks after the last treatment. Overall improvement was assessed by patient global assessment (PGA) and investigator global assessment (IGA). Depression scores for the evaluation of wrinkles were objectively assessed by Antera 3D system. Results Both sides of the face led to clinical improvement in both mean PGA and IGA. Combination treatment demonstrated a greater improvement in both mean PGA and IGA compared with FMR alone. In addition, wrinkle grading scales and depression scores showed greater improvement in the combination group than in FMR alone. Conclusion This study demonstrated that FMR and TFL comprise a good combination treatment for the treatment of wrinkles because both treatments have a synergistic effect on wrinkle improvement.

IMPORTANCE: Narrowband UV-B (NBUVB) phototherapy has been the mainstay in the treatment of vitiligo, but its long-term safety in terms of photocarcinogenesis has not been established. OBJECTIVES: To investigate the risks of skin cancer and precancerous lesions among patients with vitiligo undergoing NBUVB phototherapy, based on the number of NBUVB phototherapy sessions. DESIGN, SETTING, AND PARTICIPANTS: This nationwide population-based retrospective cohort study enrolled 60 321 patients with vitiligo 20 years or older between January 1, 2007, and December 31, 2017. Patients and outcomes were identified through nationwide cohort data from the Korean national health insurance claims database, and frequency matching by age and sex was performed. EXPOSURES: The number of phototherapy sessions each patient received between 2008 and 2017. Patients were classified into 5 groups according to the number of phototherapy sessions (0 sessions, 20 105 patients; 1-49 sessions, 20 106 patients; 50-99 sessions, 9702 patients; 100-199 sessions, 6226 patients; and ≥200 sessions, 4182 patients). We also identifed patients who underwent at least 500 phototherapy sessions (717 patients). MAIN OUTCOMES AND MEASURES: Primary outcomes were the development of actinic keratosis, Bowen disease, nonmelanoma skin cancer, or melanoma after enrollment. RESULTS: Among the 60 321 patients with vitiligo in this study (33 617 women; mean [SD] age, 50.2 [14.9] years), the risks of Bowen disease (

Since localized treatment for vitiligo is as essential as systemic treatment, a reliable instrument for target evaluation is needed besides those for whole body evaluation. We developed the Vitiligo Extent Score for a Target Area (VESTA) using reference images of both marginal and perifollicular repigmentation to measure the repigmentation rate (%) in a target lesion. In the validation study, a total of 65 dermatologists in 10 institutes evaluated 17 pairs of vitiligo images (pre- and post-treatment) using both a rough estimate and the VESTA. The VESTA (concordance correlation coefficient: 0.949, 95% confidence interval [CI] 0.942-0.955) was significantly more accurate than the rough estimate (0.896, 95% CI: 0.883-0.908). It was also associated with better inter-rater reliability over the rough estimate, albeit not significant. The VESTA can afford intuitive, convenient, and reliable assessment of the treatment response in a target area, and would be useful in clinical practice as well as retrospective studies.

Yonsei Dermatology celebrated its centennial in 2017, marking 100 years since Kung Sun Oh established the first Department of Dermatology and Urology in Korea in 1917. Following the footsteps of Kung Sun Oh, a pioneer of Korean dermatology, its members united and worked to provide the best medical service and achieve academic milestones in dermatology. Over the past hundred years, Yonsei Dermatology has played a pivotal role in the advancement of medical science and academia in Korea. The main activities of the department include medical care, education, and dermatologic research. Its research activities have encompassed a wide spectrum of dermatologic manifestations from skin immunology and pathology to introduction of newly developed treatment technologies. As Kung Sun Oh was the first Korean professor of dermatology at Severance Medical School and a passionate educator, we continue to serve his will by nurturing medical students and dermatology specialists to serve as global medical leaders. The Kung Sun Oh Memorial Lecture, first hosted in 1977, was the beginning of mutual international academic exchange in the field of dermatology in Korea. The memorial lecture has played a major role in advancing the academic status of Korean dermatological science by inviting distinguished dermatologists from around the world as guest lecturers. Yonsei Dermatology has played a key role in the history of modern medicine and dermatology in Korea over the last 100 years and continues to make an impact.

Background/Aims: Radiation-induced skin fibrosis is a common side effect of clinical radiotherapy. Our previous next-generation sequencing (NGS) study demonstrated the reduced expression of the regulatory α subunit of phosphatidylinositol 3-kinase (PIK3r1) in irradiated murine skin. Metformin has been reported to target the PIK3-FOXO3 pathway. In this study, we investigated the effects of metformin on radiation-induced skin fibrosis. Methods: Metformin was orally administered to irradiated mice. Skin fibrosis was analyzed by staining with H&E and Masson’s trichrome stain. The levels of cytokines and chemokines associated with fibrosis were analyzed by immunohistochemistry and quantitative RT-PCR. The roles of PIK3rl and FOXO3 in radiation-induced skin fibrosis were studied by overexpressing PIK3rl and transfecting FOXO3 siRNA in NIH3T3 cells and mouse-derived dermal fibroblasts (MDF). Results: The oral administration of metformin significantly reduced radiation-induced skin thickening and collagen accumulation and significantly reduced the radiation-induced expression of FOXO3 in murine skin. Additionally, the overexpression of PIK3r1 reduced the radiation-induced expression of FOXO3, while FOXO3 silencing decreased the radiation-induced expression of TGFβ in vitro. Conclusions: The results indicated that metformin suppresses radiation-induced skin injuries by modulating the expression of FOXO3 through PIK3r1. Collectively, the data obtained in this study suggested that metformin could be a potent therapeutic agent for alleviating radiation-induced skin fibrosis.

Despite a longstanding controversy surrounding TiO2 materials, TiO2 polymorphs with heterojunctions composed of anatase and rutile outperform individual polymorphs because of the type-II energetic band alignment at the heterojunction interface. Improvement in photocatalysis has also been achieved via black TiO2 with a thin disorder layer surrounding ordered TiO2. However, localization of this disorder layer in a conventional single TiO2 nanoparticle with the heterojunction composed of anatase and rutile has remained a big challenge. Here, we report the selective positioning of a disorder layer of controlled thicknesses between the anatase and rutile phases by a conceptually different synthetic route to access highly efficient novel metal-free photocatalysis for H2 production. The presence of a localized disorder layer within a single TiO2 nanoparticle was confirmed for the first time by high-resolution transmission electron microscopy with electron energy-loss spectroscopy and inline electron holography. ...

Alloying two-dimensional transition metal dichalcogenides (2D TMDs) is a promising avenue for band gap engineering. In addition, developing a scalable synthesis process is essential for the practical application of these alloys with tunable band gaps in optoelectronic devices. Here, we report the synthesis of optically uniform and scalable single-layer Mo1- xW xS2 alloys by a two-step chemical vapor deposition (CVD) method followed by a laser thinning process. The amount of W content ( x) in the Mo1- xW xS2 alloy is systemically controlled by the co-sputtering technique. The post-laser process allows layer-by-layer thinning of the Mo1- xW xS2 alloys down to a single-layer; such a layer exhibits tunable properties with the optical band gap ranging from 1.871 to 1.971 eV with variation in the W content, x = 0 to 1. Moreover, the predominant exciton complexes, trions, are transitioned to neutral excitons with increasing W concentration; this is attributed to the decrease in excessive charge carriers with an increase in the W content of the alloy. Photoluminescence (PL) and Raman mapping analyses suggest that the laser-thinning of the Mo1- xW xS2 alloys is a self-limiting process caused by heat dissipation to the substrate, resulting in spatially uniform single-layer Mo1- xW xS2 alloy films. Our findings present a promising path for the fabrication of large-scale single-layer 2D TMD alloys and the design of versatile optoelectronic devices.

Background:. Keloid formation after syndactyly division is a stressful situation for patients. In our experience, digital enlargement may be involved in keloid formation following syndactyly divisions. Therefore, we aimed to identify predictive factors and reference values for keloid formation. Methods:. In this retrospective study, 11 keloid patients (seven children, four adults) and 11 nonkeloid patients after syndactyly division (control group) with the same sex, age, webspace division site, and operation were enrolled between 2008 and 2020. Using preoperative x-ray images, we compared bony width, length, area, and protruding index relative to the great toe between keloid and control groups. Additionally, reference values for keloid formation were obtained using receiver operating characteristic curves. Statistical analysis was performed using Spearman’s correlation test. Results:. When compared with the same digit in the normal foot, distal phalanx (P3) bony base width, area, and protruding index on keloid foot were significantly different between keloid group and control group. The reference values for keloid formation after syndactyly release were 1.34 for the P3 area ratio and 1.61 for the P3 triangular area ratio (using the horizontal length of the P3 base and P3 vertical length). The reliability of reference values for the P3 area ratio and P3 triangular area ratio was excellent for all patients. Conclusions:. If digital enlargement in distal phalanx is present when compared with adjacent toe in patients who had undergone primary foot syndactyly divisions, risk of keloid development should be communicated preoperatively, and preventive strategies for keloid development and close observations are required.

Phase transitions in correlated materials can be manipulated at the nanoscale to yield emergent functional properties, promising new paradigms for nanoelectronics and nanophotonics. Vanadium dioxide (VO2), an archetypal correlated material, exhibits a metal–insulator transition (MIT) above room temperature. At the thicknesses required for heterostructure applications, such as an optical modulator discussed here, the strain state of VO2 largely determines the MIT dynamics critical to the device performance. We develop an approach to control the MIT dynamics in epitaxial VO2 films by employing an intermediate template layer with large lattice mismatch to relieve the interfacial lattice constraints, contrary to conventional thin film epitaxy that favors lattice match between the substrate and the growing film. A combination of phase-field simulation, in situ real-time nanoscale imaging, and electrical measurements reveals robust undisturbed MIT dynamics even at preexisting structural domain boundaries and si...

The interface-type resistive switching devices exhibiting bipolar and multi-level resistive switching have been considered as the key component for neuromorphic device applications. To directly observe the microscopic details of underlying electrochemical redox reactions occuring at a metal/oxide interface, we implemented in situ resistive switching of TiN/Pr0.7Ca0.3MnO3 (PCMO)/Pt junction devices in a transmission electron microscope (TEM). The in situ TEM observations directly show that an intermediate reaction layer (TiOxNy), growing and shrinking in the thickness range of a few nanometers at the TiN/PCMO interface in response to the applied voltage, mainly determines the device resistance by limiting the transport of charge carriers via the Poole-Frenkel conduction mechanism. A detailed analysis of in situ TEM observations demonstrates that electrochemical redox reactions at the TiN/PCMO interface are facilitated by the electric field driven drift of oxygen as well as Ti ions with a much stronger influence of the oxygen ions. As such, the reaction kinetics are governed by the electric field acting across the TiOxNy reaction layer. This layer defines the critical field for the onset of switching, which is measured to be of the order of 106 V cm-1, a typical value at which the ionic drift velocity starts increasing exponentially with the field according to the nonlinear ionic drift model. The present results indicate that understanding the nature of the electric field driven drift of ions in a nanoscale solid electrolyte is a key to the precise control of the resistive switching of metal/insulator/metal junction devices via voltage stimulations.

we report a case of MV in which segmental IV mimicking LS progressed to non-segmental vitiligo. Clinicians need to be cautious when there is an inflammatory lesion with subtle hypopigmentation following Blaschko’s lines; the possibility of segmental IV should be considered as a differential diagnosis

Atomically thin van der Waals semiconductor films were synthesized in a three-dimensional membrane form with monolayer precision., We report wafer-scale growth of atomically thin, three-dimensional (3D) van der Waals (vdW) semiconductor membranes. By controlling the growth kinetics in the near-equilibrium limit during metal-organic chemical vapor depositions of MoS2 and WS2 monolayer (ML) crystals, we have achieved conformal ML coverage on diverse 3D texture substrates, such as periodic arrays of nanoscale needles and trenches on quartz and SiO2/Si substrates. The ML semiconductor properties, such as channel resistivity and photoluminescence, are verified to be seamlessly uniform over the 3D textures and are scalable to wafer scale. In addition, we demonstrated that these 3D films can be easily delaminated from the growth substrates to form suspended 3D semiconductor membranes. Our work suggests that vdW ML semiconductor films can be useful platforms for patchable membrane electronics with atomic precision, yet large areas, on arbitrary substrates.

An electrically degenerate layer deteriorates the optoelectric performance of a wide band gap semiconductor grown on an insulator substrate. This detrimental effect can be passively avoided by using a buffer layer to harbor various lattice defects. However, the longstanding scientific questions regarding the microscopic origin of the degenerate interface layer and the effect of local changes in the atomic structure and chemical environment at an interface on the functionality of a desired film have remained unanswered. Moreover, this is key information for the development of ultrathin optoelectronic devices. In this study, we discuss the direct observation of a degenerate interface phase at the GaN/sapphire interface on an atomic scale. By combining high-resolution transmission electron microscopy and electron energy loss spectroscopy, we detect the presence of an ultrathin (∼6.5 A) α-Ga2O3-x layer near the GaN/sapphire interface, which is subjected to ∼4.5% biaxial compressive strain and contains many oxygen vacancies. Density functional theory calculations show that the presence of a defective α-Ga2O3-x thin layer in the GaN and sapphire heterostructure remarkably reduces the band offset between the α-Ga2O3-x conduction band and the GaN valence band, thereby exerting a significant influence on the conductivity enhancement of the interface. Our results provide an unprecedented integrated picture of the degenerate interface phenomenon on an atomic scale, which would evolve the fundamental understanding about a wide band gap semiconductor heterostructure system.

A 308-nm excimer laser (EL) has been widely used to treat patients with localized vitiligo. However, data are rare on the influence of EL treatment on the risks of skin cancer. To evaluate the skin cancer risks after long-term EL treatment, we performed a nationwide population-based retrospective cohort study using the Korean National Health Insurance Claims Database. A total of 5,052 patients with vitiligo were classified into three groups according to the EL treatment sessions between 2009 and 2016: no, 50-99, and 100 or more EL treatments after 2-year washout period (2007 and 2008). Using multivariable Cox proportional hazard models, we found that the risks of actinic keratosis, non-melanoma skin cancers, and melanoma did not significantly differ among the groups, respectively. In conclusion, EL treatment would not increase the risks of premalignant skin lesions and skin cancers in patients with vitiligo. Based on our results, EL is likely to be a safe treatment option for patients with localized vitiligo.

In this work, 40 × 40 μm2 blue InGaN micro-light-emitting diodes (μLEDs) with transparent and vertical package was first demonstrated by using either double-side polished zinc oxide (ZnO) or sapphire substrate as a transparent submount. The performance of the vertical and conventional packages was compared, where the devices packaged vertically resulted in smaller blueshift in peak wavelength with increasing drive current due to the higher junction temperature. Moreover, devices packaged vertically with the sapphire submount offered 19% and 32% greater light output power at 20 and 100 A cm−2, respectively, and 18% improvement in maximum external quantum efficiency (EQE) than devices with conventional package. Finally, the peak EQE of 58% was achieved from the μLED packaged vertically using a sapphire submount.

In this study, the discharge performance of the sluice passageway of tidal power plants was investigated based on the experiments conducted in a planar open channel and three-dimensional numerical simulations. By conducting the experiments in a planar channel, it was possible to reproduce the three-dimensional flow field around the sluice passageways similar to the field condition. The discharge capability of the passageway was estimated under various flow conditions with five different channel bathymetries. The estimates of the discharge coefficient generally ranged from 1.3 to 1.45, which are significantly smaller than the values obtained from the previous study based on the two-dimensional experiment. In addition, the experimental results showed a considerable difference in the discharge coefficient among the test cases, demonstrating an apparent influence of channel bed topography on the discharge performance. Based on an intensive parametric study carried out using the numerical simulations, an optimal configuration of the width, slope, and bottom length of the apron section was suggested for maximizing the discharge capability of the sluice passageway.

The effect of reducing wave overtopping by use of the wave return wall was quantitatively analyzed based on physical experiments. The overtopping discharge for the arc seawall and the inclined seawall was measured and compared with the predictive formula that estimates reduction of overtopping by the wave return wall. When the overtopping discharge was relatively large (>), the agreement in terms of overtopping reduction rate was fairly good between the prediction and the measurement. For the condition of smaller overtopping than the above criterion, however, the discrepancy was large between the predicted and measured result. In this context, it is required to develop a better formula for estimating reduction of wave overtopping by the wave return wall.

Design formula for estimating the wave loading on the perforated caisson having two wave chambers is yet available. In this study, the analysis results are presented with the experimental data for the wave force acting on such a breakwater model. Based on the experimental results, it was able to clarify the variation of wave action according to five different wave phases that are associated with peak wave loading at the three vertical walls. Then the force adjustment factor for double-chamber caisson was estimated, similarly as Takahashi and Shimosako (1994), which needs to be further validated with subsequent experiments and practical application in the field.

Alopecia is considered an aesthetic, psychological, and social issue among modern people. Although laser-induced skin stimulation is utilized for depilation treatment, such treatment has significant drawbacks of high energy consumption, huge equipment size, and limited usage in daily life. Here, we present a wearable photostimulator for hair-growth applications using high-performance flexible red vertical light-emitting diodes (f-VLEDs). Flexible microscale LEDs were effectively fabricated by a simple monolithic fabrication process, resulting in high light output (∼30 mW mm–2), low forward voltage (∼2.8 V), and excellent flexibility for wearable biostimulation. Finally, trichogenic stimulation of a hairless mouse was achieved using high-performance red f-VLEDs with high thermal stability, device uniformity, and mechanical durability.

The internal quantum efficiencies (IQE) and carrier lifetimes of semipolar (202¯1¯) InGaN/GaN LEDs with different active regions are measured using temperature-dependent, carrier-density-dependent, and time-resolved photoluminescence. Three active regions are investigated: one 12-nm-thick single quantum well (SQW), two 6-nm-thick QWs, and three 4-nm-thick QWs. The IQE is highest for the 12-nm-thick SQW and decreases as the well width decreases. The radiative lifetimes are similar for all structures, while the nonradiative lifetimes decrease as the well width decreases. The superior IQE and longer nonradiative lifetime of the SQW structure suggests using thick SQW active regions for high brightness semipolar (202¯1¯) LEDs.