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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Preparation and Characterization of Nanostructured Electrode Materials via Polymer-Mediated Synthesis
Get PDF학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부, 2014. 8. 이종협.전기자동차와 휴대용 전자기기의 대중화 현상은 높은 에너지 밀도와 안정성을 지닌 리튬이온전지, 슈퍼캐패시터, 연료전지와 같은 에너지 저장 및 변환 장치의 개발을 가속화시키고 있다. 에너지시스템을 구성하고 있는 전극물질은 구조나 조성에 따라 성능이 크게 좌우되기 때문에 전극물질을 합성하기 위한 연구가 활발히 진행되고 있다. 높은 성능과 청정에너지원의 요구를 충족시키기 위하여 나노구조체를 갖는 전극물질에 대한 지난 수년간 많이 연구되었다. 특히, 최근 유•무기 복합 전극물질이 전세계적으로 주목받음에 따라 이러한 물질을 합성할 수 있는 공정개발 및 응용은 공학적인 관점에서 매우 중요한 연구분야가 되었다. 지금까지 나노구조체의 유•무기 복합 전극물질을 합성하는 많은 방법들이 연구되었으나, 상당수의 방법들은 많은 시간과 복잡한 공정을 필요로 하기 때문에 효율적인 전극물질 제조 공정의 연구와 개발이 요구된다.
이 학위논문에서는 리튬이온전지의 전극물질로 사용하기 위하여 고분자 매개체를 이용한 나노구조체 유•무기 복합물질 제조법을 제안하였다. 제조법에서 폴리에틸렌이민은 안정제, 템플레이트 및 금속 전구체를 흡착을 위한 활성점으로 사용되었으며, 아가로즈 젤은 이방성 결정구조 형성을 위한 매개체 및 탄소원으로 이용되었다. 이와 관련된 세부 결과에 대한 요악은 아래와 같다.
첫 번째, 폴리에틸렌이민을 매개로한 전기화학증착법을 이용하여 그래핀/Co3O4와 그래핀/NiO 필름을 합성하였다. 그래핀 옥사이드에 흡착된 폴리에틸렌이민은 양전하를 띄는 금속전구체를 잡을 수 있기 때문에 그래핀옥사이드와 금속전구체간의 복합체를 형성에 아주 중요한 역할을 수행한다. 복합체 형성을 위하여 그래핀 옥사이드를 금속전구체가 들어있는 수용액 상에 넣고 교반을 한다. 이 후, 교반된 수용액을 이용하여 전기화학증착법을 실시하였다. 제조된 물질에서 그래핀은 금속산화물 사이에 매우 고르게 분포되어 있었으며, 리튬이온전지의 음극물질로써 향상된 성능을 보여주었다.
두 번째, 높은 가역용량과 향상된 사이클 안정성을 얻기 위해 아가로스 겔을 유기주형으로 사용하여 전기화학 증착법을 통해 탄소질의 매트릭스에 박힌 형태로 존재하는 Co3O4와 NiO 복합체를 합성하였다. 사용된 아가로스 겔은 열처리를 통해 탄소물질로의 변환이 가능하며, 단일결정 성장에 중요한 역할을 수행한다. 합성된 물질은 분석을 통하여 연결된 기공구조를 형성하는 것이 관찰되었으며, 이방성 결정면 (111)을 나타내는 것을 확인하였다. 전기화학적 실험을 통하여 구조적인 특징의 우수성과 향상된 전기화학적 성질을 입증하였다.Popularization of electric vehicles and portable electornic device stimulates the development of energy storage and conversion devices, such as Li-ion batteries (LIBs), supercapacitors, and fuel cells (FCs), toward high power and energy density and high safty, which significantly depends upon the advancement of new materials used in these systems. Moreover, electrode materials play an essential role in effiency, clean and versatile use of energy. Therefore, a wide range of nanostructured electrode materials have received great attention from research to meet the demands of high performance and clean energy source. Among the several general strategies for making nanostructured electrode materials, notable progress in the study of organic/inorganic hybrid materials has been made in recent years. Although various approaches have been employed to prepare the nanostructured hybrid materials, most of the currently proposed methods obviously involve highly toxic chemicals or high temperatures and, moreover, high energy consumption and multi-step processes are required. Consequently, a more efficient process for production is needed.
In this dissertation, the nanostructured carbon/metal oxide hybrid materials prepared by polymer-mediated strategies are proposed as electrode materials for energy storage. This facile and scalable synthesis is using polyethyleneimine (PEI) as a stabilizer, template, and active site for anchoring metal precursors and agarose gel as a carbon source and mediation for the preferential growth of metal oxides. Details are as follows:
Firstly, graphene/Co3O4 and NiO thin films were prepared by the directly co-electrodeposition using PEI-assisted strategy. Water-soluble cationic PEI chains grafted onto graphene oxides (GOs) acted as a kind of trapping agent for cationic metal ions, which plays a key role in sequential complexation between GOs and cationic precursor ions such as Co2+ and Ni2+. For the formation of PEI modified GOs (PEI-GOs) and metal ion complexes, the PEI-GOs dispersion was mixed with aqueous phase of Co(NO3)2 and Ni(NO3)2, respectively. And then, the solution was used as the plating bath for coelectrodeposition. Results showed that the graphene and metal oxides were uniformly distributed on the surface of the substrate. The prepared graphene/metal oxide films were employed as an anode material for LIBs, and it exhibited not only an enhanced cycleability but also high electronic conductivity.
Secondly, a simple strategy for the synthesis of Co3O4 and NiO/carbonaceous matrix composite using an agarose gel-mediated electrodeposition is described to achieve large reversible capacity and long cycle stability of electrode. The close-packed and porous sturctures were formed by a preferential growth mechanism within a short time. Results of X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR) proved the preferential (111) growth of metal oxide embedded in carbonaceous matrix. As an anode material for lithium ion batteries, this novel structure played a positive role in producing a material with a large reversible capacity, high conductivity, and long cyclic stability. The high reversible capacity was maintained at an elevated current density. The results indicated the existence of a synergetic effect between the porous metal oxide layers and the conductive matrix in the composite.
The results suggest that the concept proposed herein can be effectively used to overcome a bottleneck problem associated with the production of organic/inorganic hybrid materials with nanostructure.Chapter 1 Introduction 1
1.1 Lithium-ion battery for energy storage system 1
1.2 Nanostructured electrode material 4
1.3 Polymer-mediated synthesis 6
1.3.1 Polyethyleneimine 6
1.3.2 Agarose gel 8
1.4 Objectives 12
Chapter 2 Facile preparation of graphene/metal oxide composites via polyethyleneimine-mediated strategy for Li-ion battery anodes 13
2.1 Synthesis of graphene/Co3O4 thin films for lithium ion battery anodes by co-electrodeposition 13
2.1.1 Introduction 13
2.1.2 Experimental 16
2.1.2.1 Preparation of graphene/Co3O4 thin films 16
2.1.2.2 Materials characterization 16
2.1.3 Results and discussion 18
2.2 Preparation via an electrochemical method of graphene films coated on both sides with NiO nanoparticles for use as Li-ion battery anodes 28
2.2.1 Introduction 28
2.2.2 Experimental 31
2.2.2.1 Preparation of PEI-modified graphene oxide 31
2.2.2.2 Electrodeposition of graphene/NiO composites film 31
2.2.2.3 Materials characterization 32
2.2.3 Results and discussion 33
Chapter 3 Preferential growth of metal oxides via agarose gel-mediated electrodeposition for Li-ion battery anodes 50
3.1 Agarose gel-mediated electrodeposition: Preferential growth of Co3O4 anode material for lithium-ion batteries 50
3.1.1 Introduction 50
3.1.2 Experimental 53
3.1.2.1 Preparation of preferentially grown Co3O4 embedded in a carbonaceous matrix 53
3.1.2.2 Materials characterization 53
3.1.2.3 Electrochemical measurement 54
3.1.3 Results and discussion 55
3.2 Synthesis of porous NiO materials with preferentially oriented crystalline structure with enhanced stability as Li-ion battery anodes 73
3.2.1 Introduction 73
3.2.2 Experimental 76
3.2.2.1 Preparation of preferentially grown NiO embedded in a carbonaceous matrix 76
3.2.2.2 Materials characterization 76
3.2.2.3 Electrochemical measurement 77
3.2.3 Results and discussion 78
Chapter 4 Summary and Conclusions 91
Chapter 5 Recommendation for Further Research 95
Bibliography 97
국문초록 105
List of publications 108Docto
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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