1,721,059 research outputs found
바이오 자기조립 기반 기능성 하이브리드 나노제작기술
No full text학위논문(박사) - 한국과학기술원 : 신소재공학과, 2010.2, [ 145 ]Molecular self-assembly is defined as ‘the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregated joined by noncovalent bonds’. As a new strategy in nanofabrication, molecular self-assembly serves as an alternative paradigm for preparing functional nanostructures. There are numerous examples involving different molecular entities: organic molecules, colloidal nanospheres, block copolymer, and others. Among various self-assembling system of soft materials, the self-assembly based on biological molecules is becoming hot issues because biological molecules have various advantages in nanofabrication: they form the hierarchically ordered structures and have diverse functionalities. Besides those advantanges, biomolecular self-assembly is considered a valuable pathway for nanofabrication due to their highly specific molecular recognition ability, the diverse chemical and biological functionalities, and environmentally benign processing.
This thesis is divided into two parts. Part I concerns “the fabrication of peptide nanomaterials \It{via} biomolecular self-assembly strategies” and Part II is a study of “the hybrid assembly of functional nanomaterials and their applications as energy devices”.
In part I, the synthesis of a variety of functional peptide nanomaterials were shown. Peptide molecules are very attractive building blocks for functional nanomaterials. In this part, peptide nanomaterials were assembled from an aromatic dipeptides consisting of two successively connected phenylalanine units, well known as a structural motif for Alzheimer plaque. Diverse of nanostructures including nanowires, nanotubes, nanoribbons, and nanospheres were fabricated with this peptide molecule. The prepared nanomaterials have flexible material properties for organic/inorganic hybridization processes. In details, (1) The nematic liquid crystalline dispersion of peptide nanowires and their alignments control with e...한국과학기술원 : 신소재공학과
Hierarchically ordered polymer films by templated organization of aqueous droplets
No full textHierarchically ordered structures facilitate the incorporation of diverse functions simultaneously. The present report introduces a simple and novel strategy for producing hierarchically ordered polymeric films. Hierarchical ordering of aqueous droplets on a polymer solution is realized by the imposition of physical confinement via various shaped gratings. After drying of the solution, well-ordered hierarchical structures were fabricated in the remaining polymer film. The size of the grating structure and the lattice size of spontaneous hexagonally packed aqueous pores comprise two different length scales, thereby offering multiscale ordering. Interfacial wetting of the polymer solution to the grating surface was crucial in terms of obtaining a highly ordered structure that can be tuned by dissolving a small amount of surfactant in the polymer solution. The present novel approach provides a new opportunity for lithography-free fabrication of complex hierarchical structures
Graphene oxide liquid crystals: a frontier 2D soft material for graphene-based functional materials
No full textGraphene, despite being the best known strong and electrical/thermal conductive material, has found limited success in practical applications, mostly due to difficulties in the formation of desired large-scale highly organized structures. Our discovery of a liquid crystalline phase formation in graphene oxide dispersion has enabled a broad spectrum of highly aligned graphene-based structures, including films, fibers, membranes, and mesoscale structures. In this review, the current understanding of the structureproperty relationship of graphene oxide liquid crystals (GOLCs) is overviewed. Various synthetic methods and parameters that can be optimized for GOLC phase formation are highlighted. Along with the results from different characterization methods for the identification of the GOLC phases, the typical characteristics of different types of GOLC phases introduced so far, including nematic, lamellar and chiral phases, are carefully discussed. Finally, various interesting applications of GOLCs are outlined together with the future prospects for their further developments.
Morphology Control of One-Dimensional Peptide Nanostructures
No full textSelf-assembly of peptides has gathered particular attentions since it may provide unique properties relying on highly specific molecular recognition and structural organization. Peptides assemble into complex nanostructures through highly specific biomolecular interactions such as hydrogen bonding and hydrophobic interaction. Among various nanostructured materials, one-dimensional nanostructures, such as nanowires, nanotubes, and nanoribbons, have been intensively investigated. However, so far, systematic investigations on the morphological variation of peptide-assembly have rarely been explored. Here we demonstrate the morphological diversity of the self-assembly of an aromatic peptide unit. The aromatic dipeptides spontaneously assembled into nanotubes, nanoribbons, and nanowires in various polar solvents. Our work provides a broad spectrum of one-dimensional nanostructured materials, which are potentially significant for nanofabrication.We thank Dr.Q.D.Nghiem for
helpful discussions.This work was supported by the
Korea Research Foundation (KRF-2005-003-D00085), the
second stage of the Brain Korea 21 Project, the Basic
Research Program of the Korea Science and Engineering
Foundation (R01-2005-000-10456-0), R0A-2008-000-
20057-0), the 21st Century Frontier Research Program
(Center for Nanoscale Mechatronics & Manufacturing,
08K1401-01010) of the Ministry of Education, Science
and Technology, the Korean Ministry of Science and Technology,
the Fundamental R&D Program for Core Technology
of Materials funded by the Ministry of Commerce,
Industry and Energy, Republic of Korea
Liquid crystalline peptide nanowires
No full textThe synthesis and liquid crystalline behavior of peptide nanowire is presented. An aromatic dipeptide rapidly assembles into robust one-dimensional nanowires having a large aspect ratio in a volatile organic solvent. The stable dispersion of rigid nanowires shows a colloidal nematic liquid crystalline phase over a broad concentration, which is particularly advantageous for fabricating well-aligned nanowire morphologies under an external field.We thank Dr C. M. Koo and Prof. D. G. Churchill for helpful discussions,
and M. J. Woo for assisting with the powder diffractometer
system. This work was supported by the Korea Research Foundation
(KRF-2005-003-D00085), Creative Research Initiatives (Center for
Time-Resolved Diffraction) of MOST/KOSEF, the second stage of
the Brain Korea 21 Project, the Basic Research Program of the Korea
Science &Engineering Foundation (R01-2005-000-10456-0), and the
Korean Ministry of Science and Technology, the Fundamental R&D
Program for Core Technology of Materials funded by the Ministry of
Commerce, Industry and Energy, Korea. Supporting Information is
available online from Wiley InterScience or from the author
액정성을 가지는 그래핀 조성물 및 그의 제조방법
No full textThe present invention relates to a graphene composition having liquid crystalline properties and a preparation method thereof, and more particularly to a graphene composition wherein graphene having useful electrical properties is uniformly dispersed in a medium, whereby it is chemically and physically stable, exhibits a liquid crystal phase in a wide temperature range and has good compatibility with other compounds, and to a preparation method thereof. In the graphene composition, liquid crystalline properties are imparted to graphene, which can be produced in large amounts and has excellent mechanical, chemical and electrical properties, and thus the graphene composition can provide a chance to apply functional carbon materials in various fields, including nanocomposites, energy storage materials, and photonics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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