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Elucidation of the mechanisms for iridescence in the feathers of the Oriental Magpie (Pica serica)
No full textStructural color; Iridescence; Melanosome; Keratin; Feather colorationFeathers of birds exhibit a wide array of colors, which can be produced by the simple deposition of pigments such as melanin and carotenoids, and/or by the interaction of light among the array of cellular components with different refractive indices such as melanin and keratin. In comparison to the pigmental color production where the density of pigments is important, less is known the cellular and developmental processes leading to structural color production is less studied. Magpies belonging to the genus Pica exhibit strong bluish and greenish iridescence in the barbules of the secondary and tail feathers respectively, but the primary feathers are black-and-white. The former feathers, in contrast to the latter, contain 3-5 layers of densely packed melanosomes embedded in keratin matrix just beneath the epicuticle. In this study, to understand the differences in melanosome formation between iridescent and non-iridescent feathers during the developmental process of feathers, morphological analysis was conducted. Also, the transcriptomes of iridescent and black-and-white feathers of three individuals of the Oriental Magpie (Pica serica) were compared using 5’ mRNA-Quant Seq in order to characterize the cellular processes responsible for the color difference among the feathers. We found greater expression of TYR, TYRP1 and MLANA in tail iridescent feathers compared with black-and-white feathers. This finding demonstrated consistent results of melanosome overproduction in iridescent feathers through morphological observations conducted under a microscope. These results suggest that greater melanosome production is responsible for the color difference between the iridescent and black-and-white feathers in the Oriental Magpie. Further study should examine the properties of the keratin matrices in iridescent and non-iridescent feathers as the process of keratin polymer synthesis is important in the attraction-depletion forces that are necessary for the formation of ordered arrays of melanosomes.|조류의 깃털은 멜라닌과 카로테노이드 같은 색소들의 침착으로 이루어지는 색소계 색상 또는 멜라닌과 케라틴과 같은 서로 다른 굴절 지수를 가진 세포 구성 요소와 빛 상호 작용을 통해 나오는 구조색을 통해 다양한 색상을 나타낼 수 있다. 이러한 구조적 색상 형성에 관련된 세포 및 발달 과정에 대한 연구는 아직 충분히 이루어지지 않은 상태이다. Pica 속에 속하는 까치는 비행 깃털에서 강렬한 푸른색과 녹색의 구조색을 나타내지만, 주요 깃털은 흑백이다. 금속성 광택을 가진 깃털의 구조는 표피 바로 아래에 케라틴 스폰지층이 있으며, 깃털의 가장자리에는 멜라노좀이 빽빽하게 3-5층으로 배치되어 있다. 본 연구에서는 까치(Pica serica)의 푸른색과 흑백 깃털의 발달형태학을 비교하기 위한 현미경 분석을 수행했고, 전사체 분석(5' mRNA-Quant Seq)을 수행하여 깃털의 색상 형성에 관여하는 세포 과정을 연구했다. 우리는 꼬리 깃털에서 TYR, TYRP1 및 MLANA 유전자의 높은 발현 및 구조색 부위에서 검정-흰색 깃털과 비교하여 케라틴 관련 유전자가 높은 발현을 보이는 것을 발견했다. 이러한 발견은 현미경으로 관찰한 발달형태학적 결과에서 금속성 광택을 가진 깃털에서 많은 양의 멜라노좀이 생성된 것과 일관된 결과를 나타내고 있다. 이러한 결과는 구조색과 흑백 깃털 간의 색상 차이가 멜라노좀 생성의 증가 및 케라틴 모세포 분화 및 케라틴화에 관여하는 유전자의 상반되는 발현 현상이 원인이라는 것을 시사하고 있다. 나아가서 구조색 부위와 아닌 깃털의 발달과정 중 멜라노좀의 분배와 케라틴 스폰지층의 특성을 조사할 예정이다.Ⅰ. Introduction · 1
Ⅱ. Materials and Methods 4
2.1 Sample preparation 4
2.2 Feather morphology 4
2.3 Differential gene expression analysis 4
2.4 GO analysis of differentially expressed gene 5
Ⅲ. Results
3.1 Feather morphology 6
3.2 Transcriptome Data Analysis 7
3.3 Gene Ontology Analysis 7
3.4 Differential Gene Expression 8
Ⅳ. Discussion 22
References 24
국문 초록 (Abstract in Korean) 27MasterdCollectio
Achieving Nearly 100% Photoluminescence Quantum Efficiency in Organic Radical Emitters by Fine-Tuning the Effective Donor-Acceptor Distance
No full textDonor-acceptor (D-A(center dot )) type luminescent organic radicals have received widespread attention as efficient doublet emitters. However, their generally low photoluminescence quantum efficiency (PLQE) and limited photostability restrict their various applications. Since unraveling the relationship between structure and properties of D-A(center dot ) type luminescent radicals remains a challenge, here, a series of tri(2,4,6-trichlorophenyl)methyl (TTM) radical derivatives, which differ by the location of their ring fusion sites and nature of their heteroatoms, is synthesized. The PLQE of isomers varies by ten times as a function of ring fusion sites. In particular, the PLQE of a radical undergoing ring fusion at the carbazole 3,4-position is as high as 98.0%. Quantum-chemical calculations show that in the case of overlapping holes and electrons, by increasing the effective distance between the D and A moieties, the radiative transition rates of the radicals increase. Also, decreasing the electronic coupling between the charge-transfer and local-excited states and avoiding large geometrical distortions between the ground state (D-0)_and the first excited state (D-1) can significantly reduce the nonradiative transition rates. This work offers a design strategy to obtain efficient and stable luminescent radicals by modifying the sites of ring fusion, which allows control of the radiative and nonradiative transition rates. © 2024 Wiley-VCH GmbHFALSEsciescopu
Tribovoltaic performance of the Schottky contact between metal and PZT ceramic
No full textThe sliding contact between a metal or semiconductor with another semiconductor can lead to a new charge generation mechanism known as the tribovoltaic effect. This effect has several advantage over the more common triboelectric effect, such as a higher rate of charge transfer and the ability to produce a direct current (DC) output directly via the junction interface. During operation, the junction interface produces a built-in electric field. In this study, we investigate the tribovoltaic effect on sliding between copper and unpoled lead zirconate titanate (PZT) ceramic. It was found that the contact between the metal and semiconducting oxide ceramic leads to the Schottky junction effect, which can effectively drive frictionally excited charges to an external load. By increasing the applied stress to PZT, we observed different current-voltage characteristic curves. The proposed electronic band behavior determines the electrical output direction in the tribovoltaic nanogenerator (TVNG). This direction depends on the built-in electric fields formed at the junction. The performance of the TVNG was tested in both series and parallel connections, observing clearly improved electrical outputs for both. The proposed TVNG can efficiently power small electronic devices, such as LEDs, and charge capacitors in a short period of time. This work expands the understanding of unconventional transport mechanisms through the Schottky contact of PZT and metal, and provides fundamental knowledge for the future development of tribovoltaic devices. © 2024 Elsevier Ltd and Techna Group S.r.l.FALSEsciescopu
3차원 디락준금속 Cd3As2 나노선 p-n 접합에서의 탄도전자수송 연구
No full textCd3As2; Dirac semimetal; Conductance quantization; Superconducting LC circuit; Fabry-Perot interference; Ballistic transport본 논문은 3 차원 위상 디락 준금속 Cd3As2 나노선의 p-n 접합에서 발생하는 탄도 전자 수송을 연구하였다. Cd3As2 는 3 차원 운동량 공간에서 선형 분산을 보이며, 이로 인해 많은 연구자들이 주목하고 있다. 이러한 선형 분산은 시간 역전 대칭, 점 대칭, 회전 대칭과 같은 대칭 깨짐을 통해 위상적으로 보호되어 바일 디락 준금속으로 전이 할 수 있다. 본 실험에서는 Cd3As2 나노선을 전계 효과 트랜지스터 구조로 제작하고, 이 아래에 2 개의 하부 게이트 전극을 만들어 하나의 Cd3As2 나노선 채널 내에 서로 다른 유형의 p-n 접합을 형성했다. 형성된 p-n 접합을 통해 각 p-n 접합 유형에서 음의 자기 저항이 어떻게 동작하는지 확인했다. 자기장을 가한 p-n 접합에서 전도도가 양자화되는 현상도 확인했다. 또한 전도양자화와 함께 나타난 Fabry-Perot 간섭을 통해 우리의 Cd3As2 나노선 소자가 1 차원적으로 탄도 수송되는 것을 확인했다. 나노선과 나노리본 유형의 Cd3As2 샘플을 비교하여 두 Cd3As2 에서 구조적으로 다른 전도 양자화를 확인하여, 이는 바일 디락 반금속에서의 3 차원 위상 현상임을 보여준다. 더불어 양자 소자로서의 가능성과 기초를 마련하기 위해 초전도 LC 회로를 만들어 Cd3As2 전계 효과 소자와 결합했다. Cd3As2 나노선의 p-n 접합은 초전도 LC 회로에 결합된 Cd3As2 나노선 전계 효과 소자를 통해 공명과 함께 전도도를 확인했으며, Cd3As2 나노선이 가진 양자 커페시턴스의 게이트 의존성으로 인한 공진 주파수 변화를 확인했다. 이는 소자의 크기가 작아지면서 발생하는 현상으로, 우리의 결과는 Cd3As2 를 양자 소자로 사용할 때 양자 커페시턴스를 고려해야 한다는 점을 제안한다. 또한 초전도 LC 회로에 결합된 Cd3As2 나노선 전계 효과 소자에서 나타난 Fabry-Perot 간섭을 분석하여, 우리의 소자의 채널 전 영역에서 탄도 수송이 이루어지고 있음을 확인했다. 이러한 결과들은 3 차원 위상 디락 반금속을 기반으로 한 미래의 양자 소자로서의 가능성을 보여준다.|This paper investigates ballistic electron transport in the p-n junction of three-dimensional topological Dirac semi- metal Cd₃As₂ nanowires. In our experiment, we fabricated Cd₃As₂ nanowires into a field-effect transistor structure, with two underlying trenched gate creating controllable p-n junctions within a single Cd₃As₂ nanowire channel. Through the formed p-n junctions, we examined how negative magnetoresistance behaves in each type of p-n junction. The phenomenon of quantum quantization was confirmed when a magnetic field was applied to the Cd₃As₂ nanowire/nanoribbon device. Additionally, We also observed the Fabry-Perot interference. These results indicated one-dimensional ballistic transport in our Cd₃As₂ nanowire/nanoribbon device. By comparing nanowires and nanoribbon type Cd₃As₂ devices, we identified structurally distinct quantum conductance in the two Cd₃As₂. This indicates the three-dimensional topological phenomena in Dirac semimetals Cd₃As₂. Furthermore, to explore the potential as a quantum device, we coupled Cd₃As₂ nanowire field-effect transistors with a superconducting LC circuit. The p-n junctions of Cd₃As₂ nanowires, coupled to the superconducting LC circuit, exhibited in resonance spectrum and current map data. We confirmed that the resonant frequency shift, influenced by the gate-dependent quantum capacitance of Cd₃As₂ nanowires. This suggests the importance of considering quantum capacitance when utilizing low dimensional Dirac semimetal or some material with as a quantum device. we observed the Fabry-Perot interference in the superconducting LC circuit coupled to Cd₃As₂ nanowire field-effect transistor. Additionally, through the analysis of Fabry-Perot interference, we determined that ballistic transport occurs across the entire channel region of our device. These results demonstrate the potential of three-dimensional topological Dirac semimetals as the foundation for future quantum devices.1. Introduction 1
1.1 Topological material 1
1.2 Mesoscopic world 1
2. Theoretical concept 3
2.1 Topological semimetal 3
2.1.1 Topological Dirac and Weyl semimetal 3
2.1.2 Dirac semimetal from band structure 4
2.1.3 Surface state in Dirac and Weyl semimetal · 6
2.1.4 Cd₃As₂ – 3D Dirac semimetal · 7
2.2 Physics in Dirac and Weyl semimetal Cd₃As₂ · 10
2.2.1 Chiral anomaly effect 10
2.2.2 Aharonov Bohm effect · 11
2.2.3 Fermi-arc transport 13
2.2.4 Shubnikov-de Haas oscillation · 16
2.3 Superconductivity 18
2.4 RF measurement 19
2.4.1 transmission line theory 19
2.4.2 lossless line 23
2.4.3 wave reflection in transmission line 24
2.4.4 impedance matching · 26
3. Design and Fabrication 29
3.1 Cd₃As₂ nanowire growth and characterization 29
3.2 Device design 31
3.3 Device fabrication 32
3.4 Measurement setup 36
4. 3D Dirac semimetal Cd₃As₂ nanowire p-n junction · 39
4.1 Introduction 39
4.2 p-n junction · 41
4.3 Magnetoresistance in p-n junction 45
4.4 Conductance quantization 49
4.5 Fabry-Perot interference 57
5. Superconducting resonator coupled to Cd₃As₂ nanowire 61
5.1 introduction 61
5.2 p-n junctions in RF measurement and DC measurement 63
5.3 Resonance shift and quantum capacitance · 68
5.4 Long coherent Fabry-Perot interference 73
6. (Additional experiment) Charge pumping on double quantum dot in InAs
nanowire 78
6.1 Introduction · 78
6.2 Experimental results 80
6.3 conclusion 94
Reference 95
Summary in Korean · 106DoctordCollectio
Solvation Tuning Dilution of High Concentration Linear Carbonate Electrolytes for Achieving Fast Charging Capability of Li-ion Batteries
No full text급속 충전Ⅰ. Introduction 1
1.1 Overview of lithium-ion battery 1
1.2 Challenges of fast charging · 2
1.3 Electrolytes design for fast charging 3
1.4 Research goal 4
Ⅱ. Experimental method
2.1 Electrode fabrication 6
2.2 Cell assembly 6
2.3 Electrochemical testing 6
2.4 Characterization 7
2.5 Computational simulation 8
Ⅲ. Result and Discussion
3.1 Electrolyte design: PHCEs · 10
3.2 Changes in solvation structure depending on the type of diluent 13
3.3 Interfacial changes due to variation in solvation structure · 16
3.4 Scenarios of anion and additive co-derived SEI formation with HCE and PHCEs 21
3.5 Electrochemical performances of Li-ion full cells under extreme conditions 22
Ⅳ. Conclusion · 26
References 27
Summary in Korean · 32MasterdCollectio
Method of determining and maintaining scanning parameters for optimal lissajous scanning
No full text본 발명은 최적 리사쥬 스캐닝을 위한 스캐닝 조건 결정 및 유지 방법에 관한 것이다. 본 발명에 따르면, 2축에 대해 각각 기 설정된 주파수 범위 내의 주파수 조합에서 매핑 시간 지연 차이에 따른 최소 스캐닝 밀도를 최대로 하는 경우의 주파수 조합 및 매핑 시간 지연 차이를 최적 스캐닝 조건으로 선택하는 단계; 및 실제 위상 변화에 따라 조절된 지연 인덱스로 인해, 실제 시간 지연 차이와 상기 최적 스캐닝 조건으로 선택된 최적 시간 지연 차이 사이의 편차를 보상하기 위해 변조된 구동 위상 오프셋을 인가하여 최적 스캐닝을 유지하는 단계를 포함한다. 이와 같이 본 발명에 따르면, 리사쥬 스캐닝을 구현함에 있어서 소수점을 가진 주파수 조합에서 보다 유연하게 주파수 조합을 선택할 수 있다. 또한, 최적의 스캐닝 조건을 결정하고 지속적으로 일정 수준 이상의 스캐닝 밀도를 보장할 수 있다
저전압 입력 전압에서 동작이 가능한 높은 전력효율을 갖는 선형 레귤레이터
No full textlow dropout regulator(LDO);self-oscillating charge pump(SOCP);NMOS pass transistor;highly power-efficient;low VIN operationⅠ. Introduction 1
1.1 Background 1
1.1.1 Types of PMIC 1
1.1.2 Structure of power managing for battery-powered SoC 3
ⅠI. Literature Review 7
2.1 Conventional LDOs 7
2.1.1 Conventional ALDOs 7
2.1.2 Conventional DLDOs 8
2.2 ALDOs Targeted of Low Input Voltage 9
2.2.1 Time-based ALDOs 10
2.2.2 ALDOs with multi-stage EA 11
2.3 Pass Transistor under Low VDO conditions 12
2.3.1 Relationship between VDO and IL 13
2.3.2 Pass transistor selection 15
2.3.3 Limitation for lowering VDO in NMOS LDOs 16
ⅠII. Proposed System 19
3.1 System Design 19
3.1.1 Target specification of proposed LDO 19
3.1.2 Overall architecture of proposed LDO 20
3.2 Circuit Design 22
3.2.1 Self-oscillating charge pump(SOCP) 22
3.2.2 Delay cell 24
3.2.3 Invert phase-synchronized SOCP(I-SOCP) 25
3.2.4 Error amplifier(EA) 26
3.3 Stability Analysis 28
ⅠV. Measurement Results and Conclusions 35
4.1 Measurement Results 35
V. Conclusions and Future Works 47
5.1 Conclusions 47
5.2 Future Works 48
References 50MasterdCollectio