429 research outputs found
Electrochemical potential profiles of molecule junctions using constrained-search density functional study
No full textOrganic Transistor-Based Chemical Sensors for Wearable Bioelectronics
No full textCONSPECTUS: Bioelectronics for healthcare that monitor the health information on users in real time have stepped into the limelight as crucial electronic devices for the future due to the increased demand for "point-of-care" testing, which is defined as medical diagnostic testing at the time and place of patient care. In contrast to traditional diagnostic testing, which is generally conducted at medical institutions with diagnostic instruments and requires a long time for specimen analysis, point-of-care testing can be accomplished personally at the bedside, and health information on users can be monitored in real time. Advances in materials science and device technology have enabled next-generation electronics, including flexible, stretchable, and biocompatible electronic devices, bringing the commercialization of personalized healthcare devices increasingly within reach, e.g., wearable bioelectronics attached to the body that monitor the health information on users in real time. Additionally, the monitoring of harmful factors in the environment surrounding the user, such as air pollutants, chemicals, and ultraviolet light, is also important for health maintenance because such factors can have short- and long-term detrimental effects on the human body. The precise detection of chemical species from both the human body and the surrounding environment is crucial for personal health care because of the abundant information that such factors can provide when determining a person's health condition. In this respect, sensor applications based on an organic-transistor platform have various advantages, including signal amplification, molecular design capability, low cost, and mechanical robustness (e.g., flexibility and stretchability). This Account covers recent progress in organic transistor-based chemical sensors that detect various chemical species in the human body or the surrounding environment, which will be the core elements of wearable electronic devices. There has been considerable effort to develop high-performance chemical sensors based on organic-transistor platforms through material design and device engineering. Various experimental approaches have been adopted to develop chemical sensors with high sensitivity, selectivity, and stability, including the synthesis of new materials, structural engineering, surface functionalization, and device engineering. In this Account, we first provide a brief introduction to the operating principles of transistor-based chemical sensors. Then we summarize the progress in the fabrication of transistor-based chemical sensors that detect chemical species from the human body (e.g., molecules in sweat, saliva, urine, tears, etc.). We then highlight examples of chemical sensors for detecting harmful chemicals in the environment surrounding the user (e.g., nitrogen oxides, sulfur dioxide, volatile organic compounds, liquid-phase organic solvents, and heavy metal ions). Finally, we conclude this Account with a perspective on the wearable bioelectronics, especially focusing on organic electronic materials and devices.11sciescopu
Quasi-Fermi level profiles across molecular junctions from multi-space constrained-search density functional theory
No full textEdge city, beyond edge city: Evolutionary urbanization by dynamics of landscape ecology
No full textHistorically, cities have been shaped by the transport system as it was considered as the most crucial element for economic growth. However, the advance of infomation technology broke the strong relationship between the city shape, the transport system and the economic growth. Since the flow of information is no longer dependant on the physical transport system today, modern cites recently show the limits of current design methods in their urban spatial structure. In the meantime. Landscape urbanism has been discussed as an alternative way of designing urban spatial structure. However, the actual method for design process is not developed yet. The problem of the method developing process is that Landscape urbanism does not have a quantitative part to materialize the concept of landscape as a structuring element. For this reason, this paper attempts to combine landscape urbanism with a quantitative tool, Spacematrix. By the marriage between them, landscape urbanism have a tool to materialize the idea of re-structuring a city with nature. At the same time, a new usage of spacematrix for design process is discovered. San Jose is a case chosen for the process of developing the method because the current situation of the city shows the struggle of the new urban transformation. It is located in the southern part of San Francisco bay, greatly overlapped with the area of silicon valley. Since the silicon valley has shown noticeable economic performance last decades, it has been gradually expanding, and reaching the periphery of the city toward the sea. Today the area cannot offer enough land for new development of the silicon valley because of the shortage of available land. Besides, the trend of sea level rising is also threatening the availability of land. As a result, the migration of silicon valley is getting accelarated every year. In the process of developing the method. Therefore, this paper focus on providing a solution for both the development issue and the flood problem based on landscape urbanism and spacematrix
식품별 비소 함유형태에 따른 체내흡수율 및 위해성 평가
No full text보건대학원/석사식품 중 무기비소는 토양, 수계 등 환경매체로부터 자연적으로 이동되어 존재함에도 불구하고, 쌀과 같이 다소비 식품에서 검출됨으로서 사회문제가 되고 있다. JECFA 등 국제기구에서는 식품 중 중금속의 안전성을 확보하기 위해 위해성 평가 기법을 이용하여 인체 안전 기준을 설정하고 있다 특히 무기비소는 적합한 동물시험 자료가 불충분하여 무기비소가 고농도로 함유된 지하수를 장기간 복용하였던 역학 연구 결과를 바탕으로 식품 인체 안전 기준이 설정된 대표적인 물질이다. 그러나 물 중 이온 상태로 존재하는 무기비소의 체내 흡수율과 식이섬유에 함유된 식품에서의 흡수율 차이로 인해 식품 섭취시 위해도는 과대평가될 우려가 존재한다.
이에 본 논문에서는 우리나라 특유의 식습관을 적용하여 무기비소 함유 가능성이 있는 곡류 중 백미, 현미와 해조류 중 톳, 미역을 선정하여 경구 섭취에 대한 생체접근률(bioaccessibility)을 추정하였다. RIVM에서 제시하고 있는 체외 소화모델 실험방법을 적용하여 조리 및 소화단계별 생체접근률을 평가하고, 이로 인한 일일섭취량을 추정하여 기존의 원재료 농도 기반의 노출량과 비교하였다. 대상 식품별로 각각 5개의 원재료를 구매하여 원재료에서부터 단순처리(세척), 단순가공(불림, 데침) 및 소화 단계로 나누어 총 5회 반복 시험을 하였다. 각 단계별 검출농도를 이용하여 원재료 100g 당 총비소 및 무기비소 함량을 산출함으로써 조리 및 소화단계별 물질 이동량(mass balance)을 평가하였다. 또한 국민건강영양 조사 자료(2008~2010)에서 산출된 대상 식품의 연령별 일일식이량을 이용하여 생체접근률 적용 유무에 따른 일일섭취노출량을 추정하여 JECFA의 인체안전수준(PTWI)과 비교하였다.
본 논문의 주요 결과는 다음과 같다. 각 식품 원재료에 대한 총비소 평균 농도는 백미 0.046±0.004 ㎎/㎏, 현미 0.401±0.012 ㎎/㎏, 톳 11.1±1.0 ㎎/㎏, 미역 9.0±2.6 ㎎/㎏ 이었다. 무기비소는 백미 0.039±0.002 ㎎/㎏, 현미 0.052±0.004 ㎎/㎏, 톳 5.294±0.510 ㎎/㎏수준이었으며, 이는 식품의약품안전처의 조사 농도와 유사하였다(식품의약품안전처 2012, 2013).
백미와 현미의 세척과정에 의해 원재료 농도 대비 총비소의 88%가 감소하였으며, 톳과 미역의 불림, 데침 과정에 의해서 총비소 27%가 감소하였다. 원재료 농도 대비 체외 소화모형에 의한 소화액 중 농도를 이용하여 추정된 생체접근률은 총비소의 경우 백미 57%, 현미 39%, 톳 15%, 미역 29%로 추정되었다. 무기비소의 생체접근률은 백미 50%, 현미 23%, 톳 21%로 추정되었다. 따라서 원재료 농도에 비해 소화과정에 의한 생체접근률을 보정한 위해도는 총비소 생체접근률 적용시 백미 43%, 현미 61%, 톳 84%, 미역 87%의 감소를 보였다.
이상의 연구결과를 통해 세척, 데침, 불림 등의 적절한 조리방법이 비소와 같은 수용성 유해물질을 효과적으로 저감할 수 있을 것으로 관찰되었다. 또한 물 중 비소와는 달리, 식이섬유에 함유되어 있는 비소의 소화기를 통한 생체접근률은 높지 않은 것으로 추정되었다. 따라서 현미, 톳 등과 같이 식이섬유질이 높은 식품의 경우 원재료 농도 기반의 위해성 평가시 실제 노출수준보다 과대평가 될 가능성이 있었다. 특히 식이 섬유의 함량이 높을수록 생체접근률은 반대로 낮아지는 것으로 관찰된 바, 이를 이용한 건강한 식이습관을 제시할 수 있을 것이다.ope
‐Bridge Spacer Embedded Electron Donor–Acceptor Polymer for Flexible Electrochromic Zn‐Ion Batteries
No full textZinc-ion batteries (ZIBs) have drawn much attention for next-generation energy storage for smart and wearable electronics due to their high theoretical gravimetric/volumetric energy capacities, safety from explosive hazards, and cost-effectiveness. However, current state-of-the-art ZIBs lack the energy capacity necessary to facilitate smart functionalities for intelligent electronics. In this work, a "p-bridge spacer"-embedded electron donor-acceptor polymer cathode combined with a Zn2+-ion-conducting electrolyte is proposed for a smart and flexible ZIB to provide high electrochromic-electrochemical performances. The p-bridge spacer endows the polymeric skeleton with improved physical ion accessibility and sensitive charge transfer through the cycles, providing extremely stable cyclability with high specific capacity (110 mAh g(-1)) at very fast rates (8 A g(-1)) and large coloration efficiency (79.8 cm(2) C-1) under severe mechanical deformation over a long period. These results are markedly outstanding compared to the topological analogue without the p-bridge spacer (80 mAh g(-1) at current density of 8 A g(-1), 63.0 cm(2) C-1). The design to incorporate a p-bridge spacer realizes notable electrochromism behaviors and high electrochemical performance, which sheds light on the rational development of multifunctional flexible-ZIBs with color visualization properties for widespread usage in powering smart electronics.
sj-docx-1-tej-10.1177_20417314231226105 – Supplemental material for Therapeutic potential of luteolin-loaded poly(lactic-co-glycolic acid)/modified magnesium hydroxide microsphere in functional thermosensitive hydrogel for treating neuropathic pain
No full textSupplemental material, sj-docx-1-tej-10.1177_20417314231226105 for Therapeutic potential of luteolin-loaded poly(lactic-co-glycolic acid)/modified magnesium hydroxide microsphere in functional thermosensitive hydrogel for treating neuropathic pain by So-Yeon Park, Joon Hyuk Jung, Da-Seul Kim, Jun-Kyu Lee, Byeong Gwan Song, Hae Eun Shin, Ji-Won Jung, Seung-Woon Baek, Seungkwon You, Inbo Han and Dong Keun Han in Journal of Tissue Engineering</p
The dilemma of the upward path to structural realism and direct structural realism
No full text학위논문 (석사) -- 서울대학교 대학원 : 자연과학대학 협동과정 과학사및과학철학전공, 2021. 2. 천현득.본 논문에서 나는 구조적 실재론의 한 형태인 상향식 구조적 실재론을 명료화하고 옹호한다.
구조적 실재론은 우리가 관찰가능한 영역에 대한 지식만이 아니라 관찰불가능한 영역에 대한 지식도 얻을 수 있다고 주장한다. 그중 러셀이 제시한 상향식 구조적 실재론은 관찰가능한 지각의 구조를 인식적 기반으로 삼고, 이와 대응하는 관찰불가능한 자극의 구조에 대한 지식을 확보함으로써 경험주의와 실재론을 절충하고자 한다. 이에 따르면, 우리는 두 원리(HW원리와 MR원리)를 이용하여, 관찰가능한 구조로부터 관찰불가능한 구조를 추론할 수 있다.
프실로스는 상향식 구조적 실재론을 검토한 후, 상향식 구조적 실재론이 경험주의 동기와 실재론을 동시에 만족할 수 없다는 딜레마를 제시했다. 딜레마에 따르면, HW원리 의 역인 WH원리를 상향식 구조적 실재론이 받아들이지 않는다면, 경험주의 동기가 만 족되지 않으며, WH원리를 받아들인다면 경험주의와는 부합하지만, 실재론과는 멀어진 다. 보트시스는 상향식 구조 실재론의 구조 개념을 형식화하고 MR원리를 이용해 딜레마를 해결하려 시도한다. 그러나 보트시스는 MR원리의 역할은 논의했으면서도, MR원리의 구체적 내용은 제시하지 않아, MR원리가 어떻게 딜레마를 해결할 수 있는지는 보여주지 못했다. 나는 MR원리가 자신의 역할을 하기 위해서는, 형식적으로 어떤 내용이어야 하는지 살펴본다. 그리고 여기서 얻은 MR원리는 정당화될 필요가 있지만 보트시스는 정당화에 소홀했다는 것을 지적한다.
나는 지각의 구조가 아닌 현상의 구조를 관찰가능한 구조로 상정하는 직접 구조적 실재론에서는 MR원리가 정당화될 수 있다고 주장한다. 현대의 과학적 실재론 논의와 과학 적 실천에 부합하는 관찰가능한 구조는, 지각의 구조가 아니라 실험 설계와 이론적 고려를 거쳐 신뢰성이 확보된 데이터 모형으로 이해된다. 이러한 데이터 모형을 인식적 기반으로 삼는다면, MR원리는 기적 논증으로 정당화된다.In this paper, I clarify and defense the Russellian upward path to structural realism.
Structural realism argues that we can obtain not only knowledge of observables but unobservables. Especially, Russellian structural realism attempts to compromise between empiricism and realism by setting a structure of observable percepts as the epistemic basis for knowledge of the corresponding structure of unobservable stimuli. According to Russell, we can infer unobservable structures from observable structures using two principles (HW and MR principles).
Psillos presents a dilemma that Russellian structural realism cannot satisfy empiricists motivation and realism at the same time. According to Psillos, without WH principle, the converse of HW principle, Russellian structural realism cannot satisfy empiricists motivation. On the contrary, with the WH principle, Russellian structural realism is consistent with empiricism, but it is far from realism. Votsis formalizes concepts of Russellian structural realism and attempts to solve the dilemma using MR principle. However, Votsis discusses the role of MR principle but does not provide formal details of MR principle, so fails to show how MR principle could be used to solve the dilemma. I discuss what form MR principle should be to play the role. I also point out that proper MR principle needs to be justified, but Votsis did not justify it.
I argue that MR principle can be justified in direct structural realism, which regards structures of phenomena as observable structures, not perceptual structures as observable structures. Observable structures that accord with modern scientific realism discussions and scientific practice should not be understood as structures of percepts, but as data models that gain their reliability through scientists experimental design and theoretical considerations. If these data models are understood as the basis for scientific knowledge, MR principle can be justified by the 'No Miracle Argument'.1. 도입 1
2. 과학적 실재론과 상향식 구조적 실재론 4
2.1. 과학적 실재론 논쟁과 최선의 절충 4
2.2. 러셀의 상향식 구조적 실재론 9
3. 구조적 실재론의 딜레마와 MR원리의 구체화 17
3.1. 프실로스의 딜레마 17
3.2. 보트시스의 대응 22
3.3. MR원리는 정확히 어떤 원리인가 28
4. 직접 구조적 실재론 36
4.1. 지각에서 현상으로 36
4.2. 기적 논증과 MR원리 42
5. 결론: 경험주의적 실재론 53
참고문헌 56Maste
sj-tif-2-tej-10.1177_20417314231226105 – Supplemental material for Therapeutic potential of luteolin-loaded poly(lactic-co-glycolic acid)/modified magnesium hydroxide microsphere in functional thermosensitive hydrogel for treating neuropathic pain
No full textSupplemental material, sj-tif-2-tej-10.1177_20417314231226105 for Therapeutic potential of luteolin-loaded poly(lactic-co-glycolic acid)/modified magnesium hydroxide microsphere in functional thermosensitive hydrogel for treating neuropathic pain by So-Yeon Park, Joon Hyuk Jung, Da-Seul Kim, Jun-Kyu Lee, Byeong Gwan Song, Hae Eun Shin, Ji-Won Jung, Seung-Woon Baek, Seungkwon You, Inbo Han and Dong Keun Han in Journal of Tissue Engineering</p
A Single-Center Retrospective Analysis of Periprocedural Variables Affecting Local Tumor Progression after Radiofrequency Ablation of Colorectal Cancer Liver Metastases
No full textBackground: Local tumor progression (LTP) is associated with poorer survival in patients undergoing radiofrequency ablation (RFA) for colorectal liver metastasis (CLM). An algorithmic strategy to predict LTP may help in selection of patients who would benefit most from RFA for CLM. Purpose: To estimate local tumor progression-free survival (LTPFS) following RFA of CLM and develop an algorithmic strategy based on clinical variables. Materials and Methods: In this retrospective study, between March 2000 and December 2014, patients who underwent percutaneous RFA for CLM were randomly split into development (60%) and internal validation (40%) data sets. Kaplan-Meier method was used to estimate LTPFS and overall survival (OS) rates. Independent factors affecting LTPFS in the development data set were investigated by using multivariable Cox proportional hazard regression analysis. Risk scores were assigned to the risk factors and applied to the validation data set. Results: A total of 365 patients (mean age, 60 years 6 11 [standard deviation]; 259 men) with 512 CLMs were evaluated. LTPFS and OS rates were 85% and 92% at 1 year, 73% and 41% at 5 years, 72% and 30% at 10 years, and 72% and 28% at 15 years, respectively. Independent risk factors for LTP included tumor size of 2 cm or greater (hazard ratio [HR], 3.8; 95% CI: 2.3, 6.2; P < .001), subcapsular tumor location (HR, 1.9; 95% CI: 1.1, 3.1; P = .02), and minimal ablative margin of 5 mm or less (HR, 11.7; 95% CI: 4.7, 29.2; P < .001). A prediction model that used the risk factors had areas under the curve of 0.89, 0.92, and 0.90 at 1, 5, and 10 years, respectively, and it showed significantly better areas under the curve when compared with the model using the minimal ablative margin of 5 mm or less alone. Conclusion: Radiofrequency ablation provided long-term control of colorectal liver metastases. Although minimal ablative margin of 5 mm or less was the most dominant factor, the multifactorial approach including tumor size and subcapsular location better predicted local tumor progression-free survival. (C) RSNA, 202011Nsciescopu
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