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Evaluation of biological functionality of biomaterial surface modified by advanced laser equipment
No full textThe study presents a novel high focus laser scanning (HFLS) system, which integrates the advantages of conventional equipment, and demonstrates its superiority. The biological functions of biomaterial surfaces modified using HFLS were investigated. The advantages of HFLS, including ease of use, processing speed, and precision, were validated via morphological analyses such as microscopy, and surface characterization techniques such as contact angle measurements. The material surfaces were modified into the 'Line' and the 'Grid' shapes to facilitate further investigations on cellular response and drug delivery. Cell adhesion, migration, and proliferation were examined to investigate cellular responses to HFLS-modified material surfaces. To evaluate the functionality of HFLS-modified materials as drug carriers, prednisolone (PDS) holding capacity, drug release, platelet adhesion, and western blot analysis for inflammatory cytokines were performed. Compared with conventional methods, HFLS processing proved to be faster and more precise, enabling easy modification of materials into hydrophilic (the Line) or hydrophobic (the Grid) surfaces. The highest contact angle (158.63 degrees +/- 1.26) was observed for surfaces processed with a 50 mu m wave size. Cell culture medium spread across nearly the entire surface on the Line compared to the control, whereas minimal spread was observed on the Grid. These results align with those of cell adhesion, migration, proliferation, and platelet adhesion assays. Moreover, HFLS-modified materials demonstrated increased PDS retention, with PDS release occurring in a controlled manner rather than disappearance due to rapidly drug eluted. The released PDS maintained an anti-inflammatory effect, reducing the expression of cytokines associated with M1 macrophages. The laser system presented in this study proposes a promising approach for enhancing tissue engineering applications, including surface morphology modification, cytocompatibility improvement, and efficient drug delivery. Additionally, it holds potential for clinical accessibility as an equipment owing to its versatility.TRUEsciescopu
Computational discovery of Mg-based garnet structures with enhanced battery performance
No full textIn the burgeoning landscape of power source technologies, Mg-ion batteries have emerged as a promising alternative to the widely used Li-ion batteries due to the large natural abundance and divalence of magnesium. As an attempt to develop working Mg-ion batteries, for which securing efficient cathode materials with high energy density and ion mobility is crucial, we carry out electronic structure calculations based on density functional theory (DFT) to uncover high-performance garnet-type cathode materials, Mg3V1.5Cr3.5O12 (MVCO) and Mg3V3Mn2O12 (MVMO), for efficient Mg-ion batteries. Our DFT calculations demonstrate that MVCO (MVMO) not only achieves a high average voltage of 2.79V (2.69V) and energy density of 856 Wh/kg (821 Wh/kg) but also presents small volume change of 4.5 % (4 %) and low ion migration barrier of 395 meV (190 meV). It is further found out that although oxygen atoms participate in the redox reaction during the (de)intercalation process, the strong orbital hybridization between oxygen and transition metal elements prevents forming (O-O)n− dimers and thus oxygen release is likely to be suppressed, ensuring structural stability. Combined with high likelihood of successful synthesizability as is evidenced through comparison with the amorphous limits, these materials properties make the proposed garnet-structured magnesium compounds appealing candidates for post-Li energy storage solutions. © 2025 Elsevier B.V., All rights reserved.TRUEsciescopu
The politics of scaling in AI: Toward research agendas for the social studies of generative AI models
No full text이 글은 생성형 인공지능(Generative AI)의 등장 이후 이 기술이 연구개발과 사용 현장에서 전개되는 구체적인 실천 양상을 살펴보고 이를 바탕으로 기술의 사회적 연구(social studies of technology)를 위한 새로운 연구 어젠다를 탐색하고자 한다. 특히, 거대 언어 모델(LLM)의 성공 이후 이른바 ‘스케일링 법칙(scaling law)’이 이 분야 기술혁신에서 핵심 원칙이 되고 있다는 점에 주목한다. AI 모델의 매개변수와 데이터 수 등을 증가시키면 모델의 성능을 계속 향상시킬 수 있다는 주장이 하나의 자연법칙처럼 반복되면서 기술기업 등은 모델의 규모를 끝없이 확대하면서 경쟁하고 있다. 이 글은 컴퓨터과학자들처럼 스케일링 법칙을 경험적 자연법칙처럼 간주하기보다는 AI 연구개발을 둘러싼 새로운 기술정치의 핵심 요소로 다룰 것이다. 이는 AI 기술을 구성하는 다양한 담론적·정치경제적·물질적·실천적 요소들을 드러냄으로써 탈역사적이고 신비적인 것처럼 보이는 AI 기술을 ‘불안정하게’ 만들고자 하는 시도다. 무엇보다 이 글은 LLM의 연구개발, 유지와 사용 현장에서 작동하는 기술정치를 이해하기 위한 개념으로 ‘스케일링의 정치(politics of scaling)’를 제안하고자 한다(Pfotenhauer et al., 2022). 이 연구는 과학연구 논문과 연구개발 실천을 다룬 현장 사회과학 연구를 검토하고, 일부 면담 자료를 바탕으로 스케일링의 정치가 작동하는 방식을 분석한다. 이를 통해 스케일링의 정치를 분석적으로 접근할 수 있는 연구 어젠다로 스케일 낙관주의, 마찰의 선택적 가시화, 거대 실험주의를 제시한다. 이 요소들은 스케일링의 정치를 구성하면서 AI 모델의 사회적 연구를 하려는 이들에게 새로운 연구 주제들을 구체적으로 제공해 준다. 이런 분석은 AI 모델의 규모가 끝없이 확대되는 과정에서 인식론적 믿음, 가치평가 도구, 정치경제적 조건, 담론 지형 등이 상호 결합해 특정한 권력을 형성하고 있다는 점을 보여준다. 이 연구는 AI 기술혁신이 주도하는 최근의 변화를 스케일링의 정치로 이해할 가능성을 제시하면서 기술의 사회적 연구가 개입할 수 있는 다양한 지점을 마련하는 데 기여할 것이다.kc
Investigation of Film Morphology and Device Performance Based on Size-Controlled Bulk-Heterojunction Nanoparticles in Organic Photodetector
No full textBulk-heterojunction systems, which are based on donor and acceptor, have been studied as active layers of organic electronic devices owing to their various advantages including simple fabrication, broadband absorption, and efficient charge generation. Recently, to expand the utilization scope of bulk heterojunction systems into industrial applications, various research on bulk-heterojunction nanoparticles (BHJ-NPs)-based electronic devices have attracted attention due to the possibility of environmentally friendly processes. Moreover, BHJ-NPs exhibit novel properties at the nanoscale arising from their high surface area-to-volume ratio, providing potential as new organic optoelectronic materials. To successfully introduce the colloidal nanoparticle dispersion to organic electronic devices, the morphology control of BHJ-NPs films is significant. Herein, I synthesized the size-controlled PM6:Y6-based BHJ-NPs for organic photodetector and explored their size-dependent properties together with thermal-dependent phenomena, which are closely related to film morphology. Small-sized nanoparticles with a high temperature annealing of 200 °C accomplished high device performance with the enhancement of photocurrent, achieving a photosensitivity of 2.16, a photoresponsivity of 38.4 mA/W, and a specific detectivity of 2.28x10^9 Jones as critical organic phototransistor parameters. Compared to large-sized BHJ-NPs over 100 nm in diameter, high quality and fine film formation with low RMS roughness can be obtained from the small and medium-sized BHJ-NPs, showing enhanced Y6 molecular aggregation states. Furthermore, the high temperature thermal annealing (200 °C) can induce the coalescences between BHJ-NPs and increase intermolecular interactions effectively while enhancing the aggregation of donor and acceptor. Optimizing the size of BHJ-NPs and film annealing temperature improves optical and electrical properties with fine film morphology for environmentally friendly-processed nanoparticle-based organic photodetectors.MasterList of Figure v
List of Table vi
I. Introduction 1
II. Theory 3
2.1. Organic Photodetectors 3
2.1.1. Organic Photodetectors (OPDs)[15] 3
2.1.2. Structures and Working Principles of OPDs[15-17] 4
2.1.3. Device Parameters of OPDs[15] 7
2.2. Organic Semiconductors 8
2.2.1. Conjugated Polymer[18-19] 8
2.2.2. Donor & Acceptor Bulk-Heterojunction System[1,21] 10
2.2.3. PM6 & Y6[22-24] 12
2.2.4. Bulk-Heterojunction Nanoparticles (BHJ-NPs)[14,25] 14
III. Motivation 17
IV. Experimental Procedures 19
4.1. Materials 19
4.2. Synthesis and characterization of bulk-heterojunction nanoparticles 19
4.3. Device Fabrication and Characterization 22
V. Results & Discussion 23
5.1. Fabrication of nanoparticles 23
5.2. UV-Vis Absorption Spectra 27
5.3. Morphology Analysis 31
5.4. Device Performance 35
Ⅵ. Conclusion 42
Ⅶ. Reference 43
List of Figure
Figure 1. Device structures and working principles of organic photodetectors (OPDs). (a) organic
photodiode, (b) organic phototransistor 6
Figure 2. Typical I-V characteristics and transfer curve of (a) organic photodiodes, and (b) organic
phototransistors under dark and illumination conditions 6
Figure 3. Energy level diagram of organic conjugated molecules with increasing conjugation length.
Reproduced from ref [20] 9
Figure 4. Photo-induced charge transfer between donor and acceptor 11
Figure 5. Examples of donors (conjugated polymer) and acceptors (small molecule or polymer) 11
Figure 6. Molecular structures of PM6 (left) and Y6 (right) 13
Figure 7. Energy level diagram of PM6 and Y6 13
Figure 8. Schematic illustration of D/A bulk-heterojunction nanoparticle morphologies 16
Figure 9. Schematic illustration of the BHJ-NPs-based OPDs fabrication process 18
Figure 10. Schematic illustration of the BHJ-NPs synthesis process 21
Figure 11. DLS measurements of size-controlled BHJ-NPs 24
Figure 12. Photographs of the solubility test of BHJ-NPs dispersion and organic solution 26
Figure 13. Normalized UV-Vis absorption spectra of thin films of CB-based BHJ films and BHJ-NPs films
with different annealing temperatures (a) in full wavelengths, and enlarged spectra (b) in D and (c) in A
wavelengths 28
Figure 14. Normalized UV-Vis absorption spectra of size-controlled BHJ-NPs films with different annealing
temperature 30
Figure 15. SEM images of size-controlled BHJ-NPs with different magnifications 33
Figure 16. AFM topographic images of BHJ films fabricated by organic solvent (CB) 34
Figure 17. AFM topographic images of size-controlled BHJ-NPs with different annealing temperatures 34
Figure 18. Transfer curve of CB-based BHJ OPTs and BHJ-NPs (Medium NP) OPTs varying annealing
temperatures 37
Figure 19. Transfer curves of size-controlled BHJ-NPs OPTs 39
Figure 20. Output curves of CB-based BHJ OPTs and size-controlled BHJ-NPs OPTs (Solid line:
Illuminated condition, Dash line: Dark condition) 41
List of Table
Table 1. Summary of size-controlled BHJ-NPs colloidal dispersion characteristics 25
Table 2. Optical characteristics of CB-based BHJ films and BHJ-NPs films with different annealing
temperatures 29
Table 3. Device parameters of CB-based BHJ OPTs and BHJ-NPs OPTs varying annealing temperatures 38
Table 4. Device parameters of size-controlled BHJ-NPs OPTs 4
Molecular Design and Synthesis for Advanced Functional Materials: Surface Engineering of Electron Transport Layers and Dry-Developable EUV Photoresists
No full textThis study presents the molecular design and synthesis of advanced functional materials tailored for two pivotal applications: surface-engineered electron transport layers (ETLs) in organic solar cells (OSCs) and dry-developable extreme ultraviolet (EUV) photoresists for nanofabrication. For OSCs, urea-functionalized polyethyleneimine (u-PEI) was developed to modify tin oxide (SnO₂) ETLs, addressing energy-level mismatches with Y-series nonfullerene acceptors (NFAs) and mitigating surface defects. This modification significantly enhanced SnO₂ conductivity, achieving a power conversion efficiency (PCE) of 16% and improved thermal and photostability. In nanofabrication, N-heterocyclic carbene (NHC)-based metal–ligand complexes were synthesized as sustainable, etchant-free, and dry-developable EUV photoresists. These materials demonstrated exceptional sensitivity at EUV doses as low as 8.5 mJ cm⁻² and achieved resolutions of 40 nm via wet development and 80 nm via a straightforward thermal dry development process. Mechanistic insights obtained from spectroscopic analyses revealed EUV-induced polymerization, driven by secondary electron generation and styrene chain reactions. These findings offer innovative, efficient, and sustainable solutions for OSC performance enhancement and high-resolution nanolithography, advancing the frontiers of energy and nanotechnology through strategic material design.DoctorContents i
List of figures and schemes ii
List of tables v
Part Ⅰ. Bifunctional Urea-Polyethyleneimine Mediated Surface Engineering in SnO2 Electron Transport
Layer for Efficient and Stable Organic Solar Cells 1
1. Abstract 1
2. Introduction 2
Organic Solar Cells: A Sustainable Energy Solution 2
Advancements in Active Layer Donor and Acceptor Materials. 4
Role of interface properties in organic solar cells. 7
Advancements of electron transport layer materials: ZnO and SnO2 12
Application of polyethyleneimine in nonfullerene acceptor-based organic solar cells 18
3. Results & Discussion 23
Material Synthesis and Fundamental Property Analysis. 23
Impact of u-PEI Functionalization on SnO2 26
Application of u-PEI-modified SnO2 in Organic Solar Cells. 32
4. Conclusion 39
5. Experimental Section 40
NMR Spectra. 45
6. Reference 52
Part Ⅱ. Bifunctional Urea-Polyethyleneimine Mediated Surface Engineering in SnO2 Electron Transport
Layer for Efficient and Stable Organic Solar Cells 61
1. Abstract 61
2. Introduction 6 2
Recent Advances of Photolithography Patterning 62
The Evolution of EUV Photoresists: Chemically Amplified Resists 68
The Evolution of EUV Photoresists: Molecular Organometallic Resist for EUV 70
Dry Photoresist System for EUV Patterning 76
N-Heterocyclic Carbenes as a Promising Backbone for Dry Photoresists 79
Etchant-Free, Dry-Developable Photoresists: Optimization of Ligands and Metals 83
3. Results & Discussion 88
Material Synthesis and Fundamental Property Analysis. 88
EUV Analysis: Dose-Thickness Relationship and Photoelectron Spectroscopy. 95
Nanopattern Fabrication via EUV Transmission Lithography. 97
Thermal Dry Development Condition Optimization and Nanopattern Fabrication 101
EUV Reaction Analysis: NEXAFS, Raman, DFT, and XPS 105
Proposed EUV-initiated Polymerization Reaction Pathways 109
4. Conclusion 11 2
5. Experimental Section 113
NMR Spectra 118
6. Reference 12
Effective Strategies To Enhance Dehydration Kinetics in Metal Oxide Pellets for Thermal Energy Storage Materials
No full textThermochemical energy storage using Mg(OH)2 is attractive due to its high energy density, low cost, and nontoxicity. However, its practical application is limited by the high dehydration temperature required to achieve sufficient reaction rates. Although metal salt additives are known to enhance dehydration kinetics, prior studies have mainly focused on powders, with limited research on pellets. Unlike powders, pellet manufacturing involves high-temperature sintering for mechanical stability, requiring a specialized approach tailored to pellet fabrication. To overcome this, we present a strategy that simultaneously enhances the mechanical strength of Mg(OH)2 pellets through sintering and improves dehydration kinetics by introducing metal salts via postsintering infiltration. This method leads to an 80 degrees C reduction in dehydration temperature and an 8-fold increase in the maximum dehydration rate. Additionally, this study confirms that the primary factor promoting dehydration behavior is attributed to the increased active surface area and reactivity caused by the gas-liquid-solid triphasic interface formed by molten metal salt.FALSEsciescopu
Incorporation of multi-phase halogen chemistry into the Community Multiscale Air Quality (CMAQ) model
No full textHalogen radicals (Cl, Br, and I) significantly influence atmospheric oxidation capacity, affecting both O3 formation and destruction. However, understanding of halogen chemistry remains limited. To better investigate comprehensive atmospheric halogen chemistry, we incorporated halogen processes into the Community Multi-scale Air Quality (CMAQ) model: (i) emissions of Cl2, HCl, Br2, and HBr from anthropogenic sources and Br2, I2, HOI, and halocarbons from natural sources and (ii) 177 multi-phase halogen reactions. Model performance was evaluated against observed ClNO2 levels and by comparison with reported ranges of BrO and IO levels. The updated model showed significant improvements in simulating ClNO2 mixing ratios, with the index of agreement (IOA) increasing from 0.41 to 0.66 and mean bias (MB) decreasing from -159.36 to -25.07 ppt at supersites. Furthermore, simulated BrO and IO levels fell within the ranges reported in previous studies. We found that these improvements were driven by four key reactions: (i) ClO self-reaction, (ii) heterogeneous HOBr chemistry, (iii) NO2 uptake, and (iv) revised N2O5 parameterization. Based on our modeling system, we found that the presence of halogen radicals led to changes in the net Ox production rate (P(Ox)), which increased from 3.08 to 3.33 ppbh-1 on land and decreased from 0.21 to 0.07 ppbh-1 over ocean. It was noted that levels of OH, HCHO, and NOx also increased by similar to 0.007 ppt (5.5 %), similar to 0.03 ppb (1.6 %), and similar to 0.29 ppb (2.9 %), respectively, while levels of HO2 and volatile organic compounds (VOCs) decreased by similar to 0.45 ppt (5.3 %) and similar to 0.71 ppb (5.9 %). These results highlight the importance of accurately representing halogen processes in regional air quality models.TRUEsciescopu
The interplay of cellular senescence and reprogramming shapes the biological landscape of aging and cancer revealing novel therapeutic avenues
No full textCellular senescence and cellular reprogramming represent two fundamentally intertwined processes that profoundly influence aging and cancer. This paper explores how the permanent cell-cycle arrest of senescent cells and the identity-resetting capacity of reprogramming jointly shape biological outcomes in later life and tumor development. We synthesize recent findings to show that senescent cells, while halting the proliferation of damaged cells, can paradoxically promote tissue dysfunction and malignancy via their secretory phenotype. Conversely, induced reprogramming of somatic cells-exemplified by Yamanaka factors-resets cellular age and epigenetic marks, offering a potential to rejuvenate aged cells. Key findings highlight shared mechanisms (e.g., DNA damage responses and epigenetic remodeling) and bidirectional crosstalk between these processes: senescence signals can facilitate neighboring cell plasticity, whereas reprogramming attempts can trigger intrinsic senescence programs as a barrier. In aging tissues, transient (partial) reprogramming has been shown to erase senescence markers and restore cell function without inducing tumorigenesis, underlining a novel strategy to combat age-related degeneration. In cancer, we discuss how therapy-induced senescence of tumor cells may induce stem-cell-like traits in some cells and drive relapse, revealing a delicate balance between tumor suppression and tumor promotion. Understanding the interplay between senescence and reprogramming is crucial for developing innovative therapies. By targeting the senescence-reprogramming axis-for instance, via senolytic drugs, SASP inhibitors, or safe reprogramming techniques-there is significant therapeutic potential to ameliorate aging-related diseases and improve cancer treatment. Our findings underscore that carefully modulating cellular senescence and rejuvenation processes could pave the way for novel regenerative and anti-cancer strategies.FALSEsciescopu
Demand Flexibility Strategies in Electricity Markets through CDM and VPP Integration
No full textThe global push for carbon neutrality is accelerating the energy transition, driving fundamental changes in power systems. These include the emergence of Virtual Power Plants (VPPs), increasing integration of demand flexibility resources, and the growing importance of carbon pricing mechanisms. However, South Korea continues to face institutional and structural challenges in unlocking the full potential of demand response (DR) resources and in activating its underperforming carbon market. DR participation remains limited to the energy market, with virtually no integration alongside generation assets in aggregated systems such as VPPs. Moreover, the current baseline methodology lacks dynamic adjustment features, raising concerns about estimation accuracy and strategic manipulation. Korea’s carbon market also lags behind international benchmarks such as the EU-ETS and CBAM in terms of both liquidity and price signaling. To address these gaps, this study proposes a dual-track research framework. The first track introduces a DR-based Clean Development Mechanism (CDM) methodology for quantifying carbon reductions of DR resources. This approach introduces a Same-Day Adjustment (SDA) to enhance the accuracy of baseline estimation and incorporates a data-driven rebound effect model that captures load recovery behavior. The second track presents a market participation strategy for DR-integrated VPPs, supported by three sequential models: (i) an LSTM-based forecasting model, (ii) a MILP-based optimization model for market bidding, and (iii) a cooperative game-theoretic model to manage uncertainty. Case studies demonstrate that the proposed CDM methodology can yield meaningful carbon revenues—ranging from 33 to 53 KRW/kWh depending on the carbon price benchmark—thus enhancing the financial viability of DR participation. The integrated VPP strategy also proves effective in reducing risk and improving profitability, especially for small-scale operators. Overall, the study presents a strategic blueprint for aligning DR implementation with electricity and carbon market mechanisms, thereby promoting a more flexible and climate-oriented power system in Korea.Doctor1. Introduction 1
1.1. Research Background 1
2. Composition of Research 5
3. Demand Flexibility-Oriented CDM Methodology 6
3.1. CDM Methodology 7
3.1.1. Baseline 7
3.1.2. Rebound Effect 11
3.1.3. Verification 14
3.1.4. Suggestion of CDM Methodology 18
4. Market Participation of VPP 21
4.1. Proposed Market Framework 21
4.2. Market Participation Framework 21
4.2.1. Electricity Market in Korea 23
4.2.2 Framework for Three-Stage Resource Scheduling 25
4.3. Mathematical Formulation 26
4.3.1. Forecasting Model 27
4.3.2. Optimization Model 31
4.3.3. Cooperative Game Model 37
5. Case Study 41
5.1. Forecasting Results 41
5.2. Case 1: Small-scaled VPP 42
5.3. Case 2: VPP with Demand Response as a core resource 45
6. Discussion 49
6.1. Results of case 1 49
6.2. Results of case 2 49
6.2.1. Results of case 2 49
6.2.2. Adjusted Case 2 Results under Realistic DR Market Conditions 50
6.2.3. Adjusted Case 2 Results under Different Carbon Pricing Scenarios 51
6.3. Strategic Policy Directions for VPP, DR Integration, and Carbon Market Reform 52
7. Conclusion 55
Reference 5