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Hydrogen Evolution Reaction on 2D Heterostructures: From Material Design to Performance Enhancement
No full textThe urgency to address environmental concerns and energy-related challenges necessitates the advancement of sustainable and renewable energy sources, as well as the enhancement of energy storage and conversion technologies. The integration of electrochemical water splitting with extensive renewable energy harvesting systems is currently being recognized as a highly promising approach in this thesis. Moreover, hydrogen, which is generally recognized for its superior mass-energy density compared to other fuels, is commonly regarded as the optimal and most environmentally friendly energy carrier. The successful implementation of water splitting relies heavily on the advancement of economically viable, exceptionally efficient, and durable catalysts for the hydrogen evolution reaction. In recent times, there has been a notable demonstration of exceptional electrocatalytic performance in both the hydrogen evolution reaction and the oxygen evolution reaction by heterostructured catalysts. These catalysts consist of electrochemically active materials combined with various functional additions. It is worth mentioning that a few of these heterostructures, which do not contain precious metals, have demonstrated levels of activity that are equivalent to catalysts that depend on precious metals. In this way, the new class of two-dimensional (2D) semiconductors, such as transition metal oxides and chalcogenides, has gotten a lot of attention because of their unique features and possible uses in energy gathering. Besides, developing low-cost and highly efficient electrocatalysts is closely related to establishing the composition, structure, activity relationships and fundamental understanding of catalytic mechanisms. Finding 2D materials that can generate high-value electrochemistry energy harvesting through electrochemical conversion technologies in the green and sustrainable energy systems has remained challenges. Density functional theory (DFT) is becoming an important computational tool that can help us understand the relationship between the electrochemical performances and physical/chemical properties of catalysts. Improvements in DFT have had a growing effect on materials research, both in terms of basic understanding and the creation of materials for future technologies. Therefore, the main goal of this thesis is using DFT and machine learning to find out new 2D materials can be used to improve current applications in energy havesting, especially hydrogen evolution reaction (HER) catalysts, and to explain how multilayer, dopings and interface effects can be used to tune these 2D materials. Moreover, an extensive investigation into piezoelectric Janus materials establishes the fundamental basis for the advancement of these novel materials with prospective applications in the field of piezo-photoelectrochemistry in the imminent future.Docto
Distribution of volatile organic compounds by distance from industrial complexes and potential health impact on the residents
No full textVolatile organic compounds (VOCs) are the air pollutants emitted from the petrochemical industry known to pose adverse health effects on workers. The database based on the third phase of The Environmental Health Study in the Korean National Industrial Complexes (EHSNIC) in Ulsan conducted from 2018 to 2021 was used. Subjects were divided into the exposed and control group according to the estimated pollution level and distances from the industrial complexes. Ambient benzene, ethylbenzene, and xylene were significantly higher in the exposed group compared to the controls, as well as their metabolites. Risk of chronic disease and atopic dermatitis was higher in the exposed group which was supported by higher serum inflammatory markers and high hazard index of the exposed region. These results can draw attention to people engaged with environmental plans and used as primary data when making policies to reduce pollutant levels around industrial complexes
Radiologic Outcomes of Plantar Plate Repair through a Plantar Approach for the Dislocated Metatarsophalangeal Joint of the Lesser Toe
No full textBackground: A torn plantar plate (PP) is important pathologic anatomy related to a dislocated or subluxated metatarsophalangeal joint (MTPJ). Traditionally, a torn PP was treated with Weil osteotomy through a dorsal approach. However, because of the limited visualization of the dorsal approach, PP repair through a plantar approach has been proposed as a new technique. This study aimed to radiologically evaluate the outcome of PP repair through the plantar approach using an improved MTPJ overlap distance (MOD) on an anteroposterior view and the degree of subluxation on an oblique view. We also aimed to investigate the potential factors affecting the recurrence of MTPJ instability.
Methods: In this study, we included 31 patients who had a subluxated or dislocated MTPJ of the second or third toe and underwent surgical PP repair. PP repair was performed via a plantar approach after shortening metatarsal (MT) osteotomy with a dorsal approach for longer MT bone. We assessed the severity of MTPJ subluxation by measuring the MOD and subluxation subtype on radiographs. Radiologic recurrence was defined as an increase in MOD or change from subluxation type A to subluxation type B. The relationship of recurrence with clinical and radiologic factors was evaluated by comparing the recurred group against the non-recurred group.
Results: Shortening MT osteotomy was performed in 26 of 31 cases (84%). Repeated measures analysis of variance comparing preoperation, pin removal, and the latest follow-up MOD values revealed the effectiveness of PP repair through the plantar approach (p < 0.001). The MOD did not significantly change after pin removal and the latest follow-up (p = 0.130), indicating that reduction was well maintained. None of the clinical and radiologic factors were significantly related to recurrence. However, 3 of 12 rheumatoid arthritis (RA) feet (25%) recurred and 3 of 5 recurred cases (60%) were RA feet. This result suggests that RA indicated a tendency for recurrence.
Conclusions: PP repair through the plantar approach has the advantage of excellent visualization of a torn PP and direct repair. We, therefore, recommend using the plantar approach for PP repair of the MTPJ
Strength-ductility synergy in a graphene oxide reinforced aluminum matrix composite made by friction stir processing
No full textThe present study examines the influence of carbonaceous reinforcement (graphene oxide, GO) on the microstructural and mechanical properties of aluminum (Al) matrix composite fabricated by single-pass friction stir processing (FSP). GO reinforcement is introduced to the metal matrix by adhesively attaching GO powder to the surface of pure Al plates. The presence of GO within the Al matrix is initially characterized using Raman spectroscopy and secondary ion mass spectrometry, followed by detailed analysis using scanning electron microscopy and transmission electron microscopy. Due to dynamic recrystallization, significant grain refinement occurs in both FSP-treated Al alloys with and without GO conditions. However, the grains are more refined for FSP-GO condition, as the extent of dynamic recrystallization changed due to the dispersion of GO within the Al matrix. The presence of GO and its interaction with Al alloys during FSP develop superior mechanical properties (higher yield and tensile strength with greater ductility) compared to the BM and FSP-treated Al (FSP-only) conditions. The microhardness distribution shows the most hardened region on the advancing side of the stir zone, where the GO concentration is relatively high due to material flow occurring during FSP
Uncovering the clinicopathological features of early recurrence after surgical resection of pancreatic cancer
No full textTo identify risk factors and biomarker for early recurrence in patients diagnosed with pancreatic cancer who undergo curative resection. Early recurrence after curative resection of pancreatic cancer is an obstacle to long-term survival. We retrospectively reviewed 162 patients diagnosed with pancreatic cancer who underwent curative resection. Early recurrence was defined as recurrence within 12 months of surgery. We selected S100A2 as a biomarker and investigated its expression using immunohistochemistry. Of the total, 79.6% (n = 129) of patients received adjuvant chemotherapy after surgery and 117 (72.2%) experienced recurrence, of which 73 (45.1%) experience early recurrence. In multivariate analysis, age 5) was significantly lower in the early recurrence group (41.5% vs. 63.3%, P = 0.020). The cumulative incidence rate of early recurrence was higher in patients with an S100A2 H-score < 5 (41.5% vs. 63.3%, P = 0.012). The median overall survival of patients with higher S100A2 expression was longer than those with lower S100A2 expression (median 30.1 months vs. 24.2 months, P = 0.003). High-risk factors for early recurrence after surgery for pancreatic cancer include young age, lymph node metastasis, and no adjuvant therapy. Neoadjuvant treatment or intensive adjuvant therapy after surgery may improve the prognosis of patients with high-risk signatures. In patients who receive adjuvant therapy, high S100A2 expression is a good predictor
The Circadian Clock of Müller Glia Is Necessary for Retinal Homeostasis and Neuronal Survival
No full textBiological processes throughout the body are orchestrated in time through the regulation of local circadian clocks. The retina is among the most metabolically active tissues, with demands depending greatly on the light/dark cycle. Most cell types within the rodent retina are known to express the circadian clock; however, retinal clock expression in humans has not previously been localized. Moreover, the effect of local circadian clock dysfunction on retinal homeostasis is incompletely understood. The current study indicated an age-dependent decline in circadian clock gene and protein expression in the human retina. An animal model of targeted Bmal1 deficiency was used to identify the circadian clock of the retinal Müller glia as essential for neuronal survival, vascular integrity, and retinal function. These results suggest a potential role for the local retinal circadian clock within the Müller glia in age-related retinal disease and retinal degeneration
Analysis of intraocular lens decentration and tilt after femtosecond laser-assisted cataract surgery using swept-source anterior optical coherence tomography
No full textObjective
To evaluate and compare the magnitude of intraocular lens (IOL) decentration and tilt following conventional and femtosecond laser-assisted cataract surgery (FLACS) using swept-source anterior optical coherence tomography (SS-OCT).
Methods
In this retrospective observational study, we enrolled patients who underwent conventional cataract surgery or FLACS with the implantation of hydrophobic 1-piece monofocal IOL. The magnitude of IOL decentration and tilt were measured using SS-OCT. Visual acuity, intraocular pressure, spherical equivalent, axial length, contrast sensitivity, and satisfaction questionnaire were evaluated before and one-month post-surgery. Additionally, postoperative internal cylinder measurements were obtained using a wavefront aberrometer. Correlation factors between each parameter and IOL decentration or tilt were analyzed.
Results
This study included 100 eyes from 100 patients. Mean IOL decentration and tilt were 0.21 ± 0.13 mm and 5.01 ± 1.49°, respectively. Conventional cataract surgery (versus FLACS, P = 0.001) and male sex (versus female, P = 0.047) were significantly correlated with higher postoperative decentration. Preoperative lens diameter (P < 0.001), preoperative lens tilt (P = 0.007), and preoperative intraocular pressure (P = 0.027) were correlated with higher postoperative tilt. Fifty eyes that underwent FLACS demonstrated mean postoperative decentration of 0.21 ± 0.13 mm and tilt of 4.64 ± 1.48°. Compared with the conventional surgery group, the FLACS group significantly differed in postoperative decentration (0.30 ± 0.12 mm, P < 0.001) but not in tilt (5.03 ± 1.35°, P = 0.173). Postoperative visual acuity did not significantly differ between the two groups.
Conclusion
Patients who underwent FLACS demonstrated better IOL decentration and tilt than those who underwent conventional cataract surgery one-month post-surgery. However, differences in IOL decentration and tilt did not affect postoperative visual acuity
Analysis of Adhesion Force and Adhesive Energy of Ag Thin Films under Pressure Conditions Using Nanoscratch Test
No full text초고해상도 organic light-emitting diode (OLED)의 수요가 꾸준히 증가하면서 기존 증착 공정의 물리적인 한계를 극복하기 위해 전사 공정을 활용한 연구들이 활발히 진행되고 있다. 전사 공정은 전사 몰드 위의 타깃 물질을 기판으로 옮기는 공정이므로 전사 기판과 타깃 물질 간의 접합력이 전사 몰드의 접합력보다 높아야 한다. 이를 위해 전사 시 압력을 인가하는 경우가 많은데, 너무 높은 압력은 소자에 손상을 줄 수 있으므로 인가 압력에 따른 타깃 물질과 기판 간 접합력 분석이 필요하다. 이에 본 연구에서는 나노스케일에 대한 정량적인 분석이 가능한 나노스크래치 테스트를 활용하여 OLED용 소자에 인가 압력에 따른 타깃 물질과 기판 간의 접합력 및 접합에너지를 분석하였다. 그 결과, 압력을 인가하지 않거나 1 bar의 압력을 인가하였을 때보다 5 bar의 압력을 인가하였을 때 접합력이 월등히 증가하여 Si 기판이 파괴될 때까지 박리가 발생하지 않았다. 이때, 박리가 발생하지 않은 시편들의 기판 파괴 하중이 서로 달랐으며 이 차이를 사용하여 접합력을 정량적으로 비교하였다. 이를 통해 전사 공정 시 적절하게 압력을 인가하면 증착 공정보다 더 우수한 접합력을 갖는 소자를 제작할 수 있음을 확인하였다.
The demand for ultra-high-resolution organic light-emitting diodes (OLED) continues to rise, thereby driving extensive re search into transfer processes aimed at overcoming the physical limitations of conventional deposition methods. As a process that transfers target materials from a transfer mold to a substrate, the transfer process requires the adhesion between the target material and the substrate to exceed the adhesion of the transfer mold for effective bonding. To achieve this, pressure is often applied during transfer; however, excessive pressure can potentially damage the device, making it essential to thoroughly ana lyze the adhesion between the target material and substrate under varying applied pressure. In this study, nanoscratch testing, capable of detailed quantitative nanoscale analysis, was employed to evaluate the adhesion and adhesion energy between the target material and substrate in OLED devices subjected to different pressures. As a result, the adhesion significantly increased under an applied pressure of 5 bar compared to conditions without applied pressure or with 1 bar of pressure, with no de lamination occurring until the Si substrate fractured. The fracture loads varied among specimens without delamination, en abling a quantitative comparison of adhesion. These findings confirm that applying appropriate pressure during the transfer process can produce devices with superior adhesion compared to deposition methods
Aesthetic Outcomes of Rhinoplasty Performed in the Early Posttrauma Period after Nasal Bone Fracture
No full textThe optimal timing of rhinoplasty for patients with nasal bone fractures remains controversial. We investigated whether the timing of rhinoplasty after nasal trauma affects the aesthetic outcome of the procedure. A total of 41 adult patients with nasal bone fractures who underwent rhinoplasty between 2006 and 2021 were enrolled in this study. A visual analog scale (VAS) was used to indicate the assessor's satisfaction with the surgical outcome after a comparison of the pre- and postoperative facial photographs of each patient. Of the 41 patients, 28 underwent rhinoplasty within 14 days after nasal trauma (early rhinoplasty group), whereas 13 underwent rhinoplasty more than 14 days after nasal trauma (late rhinoplasty group). The rate of receiving spreader and shield graft was higher in the late rhinoplasty group (p = 0.043 and 0.018, respectively). Patients with type IV or V nasal bone fracture and patients with preoperative saddle noses had higher VAS scores than those with types I to III fractures and those without preoperative saddle nose (p = 0.003 and 0.020, respectively). There was no significant difference in overall aesthetic outcome between the early and late rhinoplasty groups. Both groups achieved significantly better radix height, dorsal height, and tip projection after rhinoplasty. The aesthetic outcome of rhinoplasty performed in the early posttrauma period is comparable with that of rhinoplasty performed more than 2 weeks after nasal bone fracture. Rhinoplasty can be considered a safe surgical treatment option for nasal bone fracture, even in the early posttrauma period. LEVEL OF EVIDENCE: : 4
A Study of Peer Reviewers’ Perceptions on Introduction ofNon-Contact Online Review for R&D Proposal
No full text이 연구에서는 COVID-19 팬데믹 이후 비대면 화상평가방식 도입에 따른 평가참여자들의 인식을 조사·분석하여 향후 정부 R&D 사업과제에 대한 비대면 평가방식 운영을 위한 함의를 도출하고자 하였다. 특히, 이 연구에서는 한국연구재단 기초연구사업 바이오 분야의 최근 4년간 평가에 평가자와 피평가자로 참여한 1,790명을 대상으로 비대면 화상평가에 관한 설문조사를 실시하고, 수집된 데이터를 활용하여 다양한 실증분석을 실시하였다. 사회 현상을 분석하고 예측하는 많은 전문가들은 비대면 인프라가 발달하고, 사회 전체가 이에 익숙해지면서 향후 대면 평가와 함께 비대면 화상평가가 병행될 가능성이 높을 것으로 추정하고 있다. 따라서, 이 연구에서는 향후 비대면 평가방식의 장점을 극대화하고, 단점을 보완할 수 있는 개선방안으로써 평가위원 간 의사소통 문제를 해결할 수 있는 방안 마련, 심층질문이 가능하도록 시스템적인 준비 필요, 비대면 화상평가 시 장비 오작동과 관련된 충분한 대응역량 강화 등을 제시하고 있다.
This study aims to analyze the evaluators and appraisees’ perception of the introduction of non-contact online conferences to review process after COVID-19 pandemic, and to derive implications for the evaluation method for the government R&D proposals the future. In particular, this study used a survey data of 1,790 evaluators and appraisers who participated in the bio part of basic research project for the National Research Foundation of Korea. Many experts who analyze and predict social phenomena predict that as non-contact infrastructure develops and all members of society become accustomed to it, there is a high possibility that non-contact online review method will be used in parallel with face-to-face evaluations method for R&D proposal in the future. Therefore, to maximizes the advantages of the non-contact online review method and to compensate for the shortcomings of the non-contact online review method, this study suggests the needs for developing a plan to resolve communication issues between evaluators, requiring systematic preparation to enable in-depth Q&A, and strengthening response capabilities related to equipment malfunction during non-contact online review