1,720,968 research outputs found
Multiscale analysis of adsorption-induced deformation of antilever-based biosensor
No full text以感測懸臂樑變形為主的生物微感測器因擁有高靈敏性、不需任何標定物、成本低廉、容易透過標準微機電製程批量生產等特性，近年來越來越受到重視。如能正確分析此微懸臂樑的表面吸附受力與變形行為，不僅能協助我們深入瞭解其力學性質，更能大幅提升設計此元件的能力。本研究目的即是希望發展多尺度模擬，適當地連結微觀的生物分子吸附機制與巨觀的撓曲變形。研究推導出一套完整多尺度理論，連接分子吸附的作用與連體懸臂樑之間的關係，對其力學行為做正確之分析與預測。在多尺度分析中推導出一可分析懸臂樑變形行為受吸附影響的解析式，將原子與量子計算中所獲得的吸附特性代入推導求得巨觀撓曲行為。本研究利用原子尺度模擬計算分析自組裝單層分子(alkanethiol)吸附性與金表面的微觀吸附現象。使用VASP進行第一原理計算，正確的模擬自組裝單層分子吸附在金表面上的行為，包含吸附能及吸附位置等皆與文獻值相近，其吸附能的最大誤差範圍在13％以內，並延伸至使用分子模擬正確計算出多碳鏈的吸附行為，誤差在7％以下。多尺度計算中，本研究將原子計算中所獲得的吸附特性代入推導，成功分析文獻中實驗數據，發現不同長度自組裝單層分子與懸臂樑的撓度成正比且呈線性關係與實驗結果相似。本研究分析出為金表面原子因受到不同長度自組裝單層分子影響，而使得原子的產生移動以及受力改變，導致表面應力不同。在最後，並提出與本研究相關的議題，作為以後延伸之參考。Microcantilever-based biosensors are rapidly becoming an enabling sensing technology for a variety of label-free biological applications due to their wide applicability, versatility and low cost. It is thus imperative for us to reveal the physical origin of adsorption-induced deformation, and to further analyze its implication of microscopic mechanisms on macroscopic deformation. The objective of this work is to develop a multi-scale theory that can analyze deformation of micro-cantilever beam subjected to bio-adsorption mechanisms calculated by ab- initio simulation and classical molecular dynamics. he multi-scale theory developed herein has successfully correlated atomistic information (the mechanism of bio-adsorption) and continuum description (bending behavior of a cantilever beam). We have studied the adsorption mechanisms of bio-molecules for SAM (self-assembly monolayer, alkanethiolic molecular for n=1~14) adsorbed on gold through ab-initio and molecular dynamics simulation. The ab-initio simulation results are in a good agreement with the literature, and the error of calculated absorption energy is less than 13％. We then extend to longer SAM simulation by molecular dynamics and the calculated absorption energy is less than 7％ when comparing with the ab-initio results.dsorption-induced stresses for different SAMs (for n=4, 6, 8, 12 and 14) are calculated by the multi-scale method. Calculated deflection based on the adsorption-induced stress agrees well with experimental measurements. Physical origin of adsorption induced deformation is revealed through the change of atomic positions and forces.目錄謝 i要 iiibstract v目錄 xi目錄 xv一章 緒論 1-1 研究背景與目的 1-2 文獻回顧 3-2-1 生物感測器基本原理 3-2-2 懸臂樑式生物微感測器實驗發展現況 7-2-3 懸臂樑式生物微感測器理論發展現況 10-2-4 SAM吸附於金表面發展之現況 11-3 研究方法與步驟 14-4 論文組織 14二章 多尺度分析生物微感測器變形行為之方法 17-1 表面應力 17-2 理論 20-2-1 原子尺度 20-2-2 連體理論─Stoney formula 22-3 多尺度分析理論推導 25-3-1 多尺度分析之目標 25-3-2 多尺度分析理論 27三章 生物感測器之吸附行為 31-1 吸附行為 31-1-1 吸附性 31-1-2 自組裝分子 32-2 原子尺度模擬計算─第一原理計算 34-2-1 原子尺度模擬分析理論 34-2-2 模型建立與模擬參數 35-3 原子尺度模擬計算─分子模擬 40-4 模擬結果分析討論 43-4-1 第一原理模擬結果 43-4-2 分子模擬結果 45四章 原子尺度模擬生物感測器 53-1 生物感測器模擬之多尺度模擬分析 53-2 多尺度分析結果 57-3 結果分析與討論 (實驗比對) 64五章 結論與建議 69-1 結論 69-2 建議 70考文獻 7
First-principles study on variation of lattice parameters of mullite Al4+ 2xSi2− 2xO10− x (x= 0.125, 0.250, 0.375)
No full textMicrocantilever biosensor: sensing platform, surface characterization and multiscale modeling
No full text
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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