Map equation for link community

Community structure exists in many real-world networks and has been reported being related to several functional properties of the networks. The conventional approach was partitioning nodes into communities, while some recent studies start partitioning links instead of nodes to find overlapping communities of nodes efficiently. We extended the map equation method, which was originally developed for node communities, to find link communities in networks. This method is tested on various kinds of networks and compared with the metadata of the networks, and the results show that our method can identify the overlapping role of nodes effectively. The advantage of this method is that the node community scheme and link community scheme can be compared quantitatively by measuring the unknown information left in the networks besides the community structure. It can be used to decide quantitatively whether or not the link community scheme should be used instead of the node community scheme. Furthermore, this method can be easily extended to the directed and weighted networks since it is based on the random walk.Comment: 9 pages,5 figure

Development of a Remote Testing System for Performance of Gas Leakage Detectors

In this research, we designed a remote system to test parameters of gas detectors such as gas concentration and initial response time. This testing system is available to measure two gas instruments simultaneously. First of all, we assembled an experimental jig with a square structure. Those parts are included with a glass flask, two high-quality cameras, and two Ethernet modems for transmitting data. This remote gas detector testing system extracts numerals from videos with continually various gas concentrations while LCDs show photographs from cameras. Extracted numeral data are received to a laptop computer through Ethernet modem. And then, the numerical data with gas concentrations and the measured initial response speeds are recorded and graphed. Our remote testing system will be diversely applied on gas detector’s test and will be certificated in domestic and international countries

Tuning orbital-selective phase transitions in a two-dimensional Hund's correlated system

Hund's rule coupling ($\textit{J}$) has attracted much attention recently for its role in the description of the novel quantum phases of multi orbital materials. Depending on the orbital occupancy, $\textit{J}$ can lead to various intriguing phases. However, experimental confirmation of the orbital occupancy dependency has been difficult as controlling the orbital degrees of freedom normally accompanies chemical inhomogeneities. Here, we demonstrate a method to investigate the role of orbital occupancy in $\textit{J}$ related phenomena without inducing inhomogeneities. By growing SrRuO$_3$ monolayers on various substrates with symmetry-preserving interlayers, we gradually tune the crystal field splitting and thus the orbital degeneracy of the Ru \textit{t_2_g$}$ orbitals. It effectively varies the orbital occupancies of two-dimensional (2D) ruthenates. Via in-situ angle-resolved photoemission spectroscopy, we observe a progressive metal-insulator transition (MIT). It is found that the MIT occurs with orbital differentiation: concurrent opening of a band insulating gap in the $\textit{d$_x_y} band and a Mott gap in the \textit{d_x$$_z$$_/$$_y$$_z} bands. Our study provides an effective experimental method for investigation of orbital-selective phenomena in multi-orbital materials

분자인식 나노재료를 이용한 형광센서 제조에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2016. 2. 장지영.Molecular imprinting has been considered as a practical way to produce materials with molecular recognition properties due to its ease of use and low cost. In this study, the fluorescent sensors based on molecularly imprinted nanomaterials were developed using various fluorescent materials as a signal transducer. Firstly, a highly sensitive molecularly imprinted fluorescent sensor was prepared by using a CdSe quantum dot (QD) as a signal transducer and a mesoporous silica nanoparticle as an imprinting material. Bisphenol A (BPA) was chosen as a model template, which is known as an endocrine disruptor. Binding sites were selectively formed between the pores and CdSe QDs were encapsulated in the pores of the mesoporous silica. QD-encapsulated, molecularly imprinted mesoporous silica particles (QD-MIMS) exhibited excellent molecular recognition properties in terms of both sensitivity and selectivity. Owing to the proximity of the binding sites to the QDs, a significant, concentration-sensitive fluorescence quenching was observed in the presence of BPA. QD-MIMS showed a linear Stern-Volmer relationship for BPA and its analogs. QD-MIMS had a much larger quenching constant for BPA (by more than ten times) than for BPA analogs, demonstrating the high selectivity of QD-MIMS. Secondly, a molecularly imprinted polymer-based fluorescent sensor was fabricated through an organogelation process. The sensor was comprised of a molecularly imprinted nanofiber as a receptor and a CdSe/ZnS quantum dot as a signal transducer. Histamine was selected as a model template. An organogelator with two different polymerizable groups, an acrylate and a diacetylene was successfully synthesized. As a functional monomer for complexation with the template, an acrylate having a carboxyl group was used. The QD and template-containing organogel formed in n-decane was polymerized in the presence of a photoinitiator and a cross-linker by UV irradiation to produce highly cross-linked organogel nanofibers. The template molecules were removed by extraction with methanol/acetic acid (9:1 v/v) to give the QD-incorporated, histamine imprinted organogel nanofibers (QD-HIOGNF). QD-HIOGNF showed high molecular recognition properties toward histamine in respects to both sensitivity and selectivity. The fluorescence intensity of QD-HIOGNF decreased sensitively as the concentration of histamine increased. QD-HIOGNF could be reused for sensing after removing the bound analytes. Thirdly, a facile and versatile sensing assay of diethylstilbestrol (DES) was developed by fabricating a molecularly imprinted fullerene-silica nanocomposites (MIFSNCs). Fullerene encapsulated in a microemulsion with the aid of the non-ionic surfactant was incorporated into the silica network by the sol-gel reaction of triethyl orthosilicate and a triethoxysilane-DES complex as silica precursors. MIFSNCs exhibited a fast kinetic binding and high molecular recognition properties in terms of both sensitivity and selectivity. MIFSNCs showed a notable fluorescence quenching under all given concentrations of DES. On the other hand, non-imprinted fullerene-silica nanocomposites (NIFSNCs) showed only a few amount of quenching for the concentrations of DES. Lastly, a molecularly imprinted mesoporous silica in which the tetraphenylethylene based AIE active chromophore was selectively introduced into the inner pore of the silica network was prepared. DES was chosen as a target molecule and connected to the triethoxysilane moieties via the thermally reversible urethane bonds. DES-selective imprinted cavities which have two-point binding sites were successfully formed between the pores of the silica framework by the sol-gel reaction and subsequent removal of DES. The AIE chromophore-grafted, DES imprinted mesoporous silica nanoparticles (TFPE-DIMS) showed a specific binding ability for the target template and a fast kinetic binding profile. The degree of fluorescence quenching of TFPE-DIMS was concentration-sensitive. The sensitivity and selectivity of TFPE-DIMS were estimated by the Stern-Volmer equation. TFPE-DIMS displayed a much larger Stern-Volmer quenching constant for DES than for DES analogs with a high molecular imprinting factor. TFPE-DIMS also showed a great recovery of its initial fluorescence intensity even after several extraction and rebinding cycles.Chapter I. Introduction 1 I-1. Molecularly Imprinting 1 I-1-1. Principle of Molecular Imprinting 1 I-1-2. Application of Molecularly Imprinted Nanomaterials for Fluorescent Sensor 9 I-2. Mesoporous Silica 13 I-2-1. Sol-Gel Reaction 13 I-2-2. Post Synthetic Functionalization of Mesoporous Silica (Grafting) 14 I-2-3. Direct Synthesis (Co-Condensation) 15 I-2-4. Periodic Mesoporous Organosilica (PMO) 17 I-3. Organogel 19 I-3-1. Definition of Organogel 19 I-3-2. Driving Force of Fibrous Networks in Organogel 20 I-3-3. Types of Organogelators 21 I-4. References 29 Chapter II. Preparation of CdSe Quantum Dot-Encapsulated Molecularly Imprinted Mesoporous Silica Nanoparticles for Fluorescent Sensing of Bisphenol A 36 II-1. Introduction 36 II-2. Experimental Section 38 II-3. Results and Discussion 42 II-3-1. Synthesis and Structural Characterization 42 II-3-2. Photophysical and Kinetic Binding Properties of QD-MIMS 48 II-3-3. Sensitivity and Selectivity Study of QD-MIMS 50 II-4. Conclusions 55 II-5. References 56 Chapter III. Preparation of a Fluorescent Sensor by Organogelation: CdSe/ZnS Quantum Dots Embedded Molecularly Imprinted Organogel Nanofibers 59 III-1. Introduction 59 III-2. Experimental Section. 61 III-3. Results and Discussion 65 III-3-1. Preparation of Organogel Nanofibers 65 III-3-2. Structural and Morphological Analysis of Organogel Nanofibers 67 III-3-3. Rebinding Performance and Sensitivity of QD-HIOGNF 70 III-3-4. Selectivity of QD-HIOGNF 72 III-3-5. Recyclability Test 75 III-4. Conclusions 77 III-5. References 78 Chapter IV. Preparation of Molecularly Imprinted Fullerene-Silica Nanocomposites for Sensitive and Selective Recognition of Diethylstilbestrol 82 IV-1. Introduction 82 IV-2. Experimental Section 84 IV-3. Results and Discussion 88 IV-3-1. Preparation and Structural Characterization 88 IV-3-2. Photophysical Properties of MIFSNCs 93 IV-3-3. Sensitivity and Competitive Rebinding Performance of MIFSNCs 95 IV-4. Conclusions 100 IV-5. References 101 Chapter V. Preparation of Highly Luminescent AIE Chromophore-Grafted Molecularly Imprinted Mesoporous Silica Nanoparticles for Fluorescent Sensing of Diethylstilbestrol 103 V-1. Introduction 103 V-2. Experimental Section 106 V-3. Results and Discussion 111 V-3-1. Synthesis and Characterization 111 V-3-2. Structural and Morphological Analysis of Mesoporous Silica Nanoparticles 114 V-3-3. Photophysical Properties 120 V-3-4. Kinetic Binding Study of TFPE-DIMS 122 V-3-5. Molecular Recognition Properties of TFPE-DIMS 123 V-3-6. Recyclability Test 126 V-4. Conclusions. 128 V-5. References. 129 국문 요약 134 List of Publications 137 List of Presentations 138Docto

Growth and characterization of superconductor-ferromagnet thin film heterostructure la1.85sr0.15cuo4/srruo3

© 2021, Korea Institute of Applied Superconductivity and Cryogenics. All rights reserved.Superconductor-ferromagnet thin film heterostructure is an ideal system for studying the interplay between superconductivity and ferromagnetism. These two antagonistic properties combined in thin film heterostructure create interesting proximity effects such as spin-triplet superconductivity. Thin film heterostructure of optimally doped La2-xSrxCuO4(LSCO) cuprate superconductor and SrRuO3(SRO) ruthenate ferromagnet has been grown by pulsed laser deposition. Its temperature-dependent resistivity and Hall effect measurements show that our LSCO/SRO heterostructure has both superconductivity and ferromagnetism. In the Hall effect measurement results, we find additional hump-like structures appear in the anomalous Hall effect signal in the vicinity of superconducting transition. We conclude that giant magnetoresistance of the LSCO layer distorts the AHE signal, which results in a hump-like structure.11Nscopuskc

Accelerated settling velocity of airborne particulate matter on hairy plant leaves

Phytoremediation has emerged as an ecofriendly technique to reduce hazardous particulate matter (PM) in the air. Although previous studies have conducted statistical analyses to reveal PM removal capabilities of various plant species according to their leaf characteristics, the underlying physical mechanism of PM adsorption of plants remains unclear. Conventional methodologies for measuring PM accumulation usually require long-term field tests and provide limited understanding on PM removal effects of individual leaf traits of various plants. In this study, we propose a novel methodology which can compare the electrostatic interactions between PMs and plant leaves according to their trichome structures by using digital in-line holographic microscopy (DIHM). Surface characteristics of Perilla frutescens and Capsicum annuum leaves are measured to examine electrostatic effects according to the morphological features of trichomes. 3D settling motions of PMs near the microstructures of trichomes of the two plant species are compared in detail. To validate the PM removal effect of the hairy microstructures, a polydimethylsiloxane (PDMS) replica model of a P. frutescens leaf is fabricated to demonstrate accelerated settling velocities of PMs near trichome-like microstructures. The size and electric charge distributions of PMs with irregular shapes are analyzed using DIHM. Numerical simulation of the PM deposition near a trichome-like structure is conducted to verify the empirical results. As a result, the settling velocities of PMs on P. frutescens leaves and a PDMS replica sample are 12.11 ± 1.88% and 34.06 ± 4.19% faster than those on C. annuum leaves and a flat PDMS sample, respectively. These findings indicate that the curved microstructures of hairy trichomes of plant leaves increase the ability to capture PMs by enhancing the electric field intensity just near trichomes. Compared with conventional methods, the proposed methodology can quantitatively evaluate the settling velocity of PMs on various plant leaves according to the morphological structure and density of trichomes within a short period of time. The present research findings would be widely utilized in the selection of suitable air-purifying plants for sustainable removal of harmful air pollutants in urban and indoor environments. © 2023 Elsevier Ltd11Nsciescopu

Smartphone-based holographic measurement of polydisperse suspended particulate matter with various mass concentration ratios

Real-time monitoring of suspended particulate matter (PM) has become essential in daily life due to the adverse effects of long-term exposure to PMs on human health and ecosystems. However, conventional techniques for measuring micro-scale particulates commonly require expensive instruments. In this study, a smartphone-based device is developed for real-time monitoring of suspended PMs by integrating a smartphone-based digital holographic microscopy (S-DHM) and deep learning algorithms. The proposed S-DHM-based PM monitoring device is composed of affordable commercial optical components and a smartphone. Overall procedures including digital image processing, deep learning training, and correction process are optimized to minimize the prediction error and computational cost. The proposed device can rapidly measure the mass concentrations of coarse and fine PMs from holographic speckle patterns of suspended polydisperse PMs in water with measurement errors of 22.8 ± 18.1% and 13.5 ± 9.8%, respectively. With further advances in data acquisition and deep learning training, this study would contribute to the development of hand-held devices for monitoring polydisperse non-spherical pollutants suspended in various media. © 2022, The Author(s).11Ysciescopu