Thesis (Ph. D.)--University of North Texas, May, 2009. / Title from title page display. Includes bibliographical references.

Energy harvesting and energy storage are two most important technologies in today's green and renewable energy science. As for energy harvesting, the fundamental science and practically applicable technologies are not only essential in realizing the self-powered electronic devices and systems, but also tremendously helpful in meeting the rapid-growing world-wide energy consumptions. Mechanical energy is one of the most universally-existing, diversely-presenting, but usually-wasted energies in the natural environment. Owing to the limitations of the traditional technologies for mechanical energy harvesting, it is highly desirable to develop new technology that can efficiently convert different types of mechanical energy into electricity. On the other hand, the electricity generated from environmental energy often needs to be stored before used to drive electronic devices. For the energy storage units such as Li-ion batteries as the power sources, the limited lifetime is the prominent problem. Hybridizing energy harvesting devices with energy storage units could not only provide new solution for this, but also lead to the realization of sustainable power sources. In this dissertation, the research efforts have led to several critical advances in a new technology for mechanical energy harvesting—triboelectric nanogenerators (TENGs). Previous to the research of this dissertation, the TENG only has one basic mode—the contact mode. Through rational structural design, we largely improved the output performance of the contact-mode TENG and systematically studied their characteristics as a power source. Beyond this, we have also established the second basic mode for TENG—the lateral sliding mode, and demonstrated sliding-based disk TENGs for harvesting rotational energy and wind-cup-based TENGs for harvesting wind energy. In order to expand the application and versatility of TENG by avoid the connection of the electrode on the moving part, we further developed another basic mode—freestanding-layer mode, which is capable of working with supreme stability in non-contact mode and harvesting energy from any free-moving object. Both the grating structured and disk-structured TENGs based on this mode also display much improved long-term stability and very high energy conversion efficiency. For the further improvement of the TENG’s output performance from the material aspect, we introduced the ion-injection method to study the maximum surface charge density of the TENG, and for the first time unraveled its dependence on the structural parameter—the thickness of the dielectric film. The above researches have largely propelled the development of TENGs for mechanical energy harvesting and brought a big potential of impacting people’s everyday life. Targeted at developing sustainable and independent power sources for electronic devices, efforts have been made in this dissertation to develop new fundamental science and new devices that hybridize the nanogenerator-based mechanical energy harvesting and the Li-ion-battery-based energy storage process into a single-step process or in a single device. Through hybridizing a piezoelectric nanogenerator with a Li-ion battery, a self-charging power cell has been demonstrated based on a fundamentally-new mechanical-to-electrochemcial process. The triboelectric nanogenerator as a powerful technology for mechanical energy harvesting has also been hybridized with a Li-ion battery into a self-charging power unit. This new concept of device can sustainably provide a constant voltage for the non-stop operation of electronic devices.

本論文主要探究竺道生思想中毘曇學闕如的現象問題，尤其側重於竺道生曾經積久學習毘曇之學，卻為何在其後來的論著當中難以尋見此般毘曇學的影響及痕跡。本論文的處理方式主要採取思想比較的進路，即透過選取毘曇學和竺道生思想中具代表性之論點，再運用分析、比較之方法，逐步釐清毘曇學在竺道生思想中所佔有的份量，以及竺道生對待毘曇學的立場、觀感等；透過補白竺道生思想中關於毘曇學的容受問題，將對於竺道生思想有著更為整全、確當的認識。同時，在回歸中國佛學發展的脈絡底下，亦能對於早期中國佛教毘曇和般若、甚至擴及大、小乘間的交涉過程、細節及其相關問題等，提供一個合理的觀察與說解。 　　在實際論述方面，第二章隸屬本論文的研究基礎。此部份包含探討中國早期毘曇文獻的翻譯與傳播、容受狀況，其用意在於呈顯、了解竺道生以前中國毘曇學的發展情形。其次，針對史傳等載錄竺道生生平遊學事跡與毘曇學接觸的史實進行考訂，其中包含竺道生接觸毘曇學的年份、地點、授予毘曇學的對象等各種細節。最後，具體論證竺道生所接觸到的毘曇學理論為何，用以釐清竺道生在各種部派毘曇學系統中的接受對象，始能明確地與後文論述般若學與毘曇學交涉的部分有所接應。 　　第三章以降，主要以思想、理論比較的方式進行。該章首先針對竺道生所接觸的毘曇學理論進行析論，主要集中在毘曇學對於「法體恆存」和「三世實有」理論的探討，其間包含毘曇學如何定義「法體」的內涵，以及由此導出「法體實有」的理路。其次，針對竺道生思想中位居核心地位的「理」概念進行考論，嘗試分析竺道生「理」概念的內涵，包含其中的觀念架構和理路推演，以及「理」概念的形成背景和基礎成分等，同時亦就竺道生言論中與「理」概念相關的其他理論內容，像是法身、悟理等概念進行延伸性的說明，以求能完整掌握道生「理」概念的特殊意義。第三部分則具體比較毘曇學「法體恆存」理論與竺道生「理」之概念在學說理論上的異同，並嘗試釐清二者間是否具有可架接或可融通之處，其間的轉圜點為何，轉出後的「理」概念是否有超越或不同於「法體實有」理論的部分，同時也觀察在道生身上當毘曇學遇到般若學時，他是否全盤的接受般若並放棄毘曇等關鍵問題。 　　接續的第四章主要進行關於修道理論的考察。由於上一章次已然確立對於法體內容的界定，而法體內涵的提出，最終仍回歸、落實於修行者的體證，故順此理路而進行修道論的比較。首先，將析論毘曇學中的修道理論，主要側重討論毘曇學中有關「漸修」與「頓斷」的關係，其中包含毘曇學對於修行次第、所斷煩惱、斷煩惱之智慧以及最終獲證果位等細節的分析。其次，論究竺道生思想中另一有關修道的核心議題──「頓悟」說，嘗試解讀竺道生「頓悟」說的內容，例如「頓」的意義指向、「悟」與「理」的關係、如何界定「頓悟」的標準、「頓悟」是否與「漸修」形成背反、相違等，同時亦針對與「頓悟」說相關的修行觀點，像是道生所認為障礙修行的主要煩惱為何、斷除煩惱所具備的智慧為何，以及其他有關修行過程的重要原則等，均在第二部分進行考論，以求能整全地發見竺道生對於修道理論的觀點。最後，專就毘曇學「漸修頓斷」理論與竺道生「頓悟」說的內容進行比對，討論其間是否有類同或相異之處，又該如何看待這些異同的部分。 　　第五章在比較、討論完法體與修道的理論後，由於凡夫修行至最終獲得成佛果位，並非一蹴可成，因此在不斷向上、向善的還滅過程中，便涉及界定善惡業報的發生及其可能造成的影響等，故須辨析業報論的層面。而由業報論衍生之問題係為「誰」來受報，故延伸之討論便觸及對眾生主體性解釋的意見差別。在實際論述上，本章仍先考察毘曇學對於業報理論的看法，箇中包含諸如「業」、「報」、「果」等個別概念定義及其種類區分，並且關注毘曇學談論業報的核心訴求為何。接著，則將集中於「業力相續」的討論；這涉及毘曇學認為業力如何延續的問題，並且擴及對眾生主體性的看法，同時亦將循此論究毘曇學在「無我」原則的堅持下如何維繫業感緣起的生發。此外，本章亦將擴及《三法度論》和犢子部立「不可說我」的內容，此係因道生很可能曾從僧伽提婆接觸到此種對眾生主體性問題的特殊意見。第二部分將考論竺道生的「善不受報」說；表面上「善不受報」似乎違逆於毘曇學承許業報存在的概念，但其實竺道生並非否認行善造惡等果報的因果鏈結關係，而是另有他所欲強調的、關於業報的看法，此係為本章次亟欲釐清的重點，故第二部分將以「善不受報」為主題線索，同時討論竺道生有關業報說的其他觀點，例如眾生未成佛前的行善造惡問題。第三部分，則比較毘曇學與竺道生對因果業報的看法、界說等，同時亦涉及二者對眾生主體性問題的立場；而究竟兩造理論間是否具有共通或迥異之處，又該如何解釋、看待道生對於業報的立場。 　　而經以上進程設定及考察後發現，竺道生係以般若學理為其思想基底，復在此上融會、貫通各類大乘經典，並且在會通各種大乘思想的過程中，亦對毘曇之學做出裁定與選擇。換句話說，竺道生思想中般若與毘曇之交涉現象，其實衍生的是他如何面對和處理大、小乘間教理取捨、定位等相關問題。而以道生為例，般若所反映的大乘空義思潮與毘曇所代表的部派佛學系統，對道生而言，最終他是擇選以般若等大乘經典為其思想歸向，也因此在他自覺地檢討、修正毘曇學問題時，遂體現出其思想形成毘曇學空白、闕如之現象。但另一方面，當談說竺道生思想以般若學為顯著特色、而以佛性義為最終歸向的同時，其間不可忽略者係是做為基層的毘曇學；正因為具備深厚、踏實的阿毗達摩基礎，道生才能在其上快速融會般若空理，然後串聯於佛性教說，並以之做為思想定位的終點，甚至可說正是因為道生具有深厚且由「部派阿毗達摩→般若經→法華經→涅槃經」的循序基底，所以才能在其上開結出以涅槃佛性為代表的思想取向，而這一切的根源自不脫離於毘曇之學。

In this thesis, two recently discovered polymorphs of LiFeSO4F, adopting a tavorite- and triplite-type structure, were investigated as potential candidates for use as cathode materials in Li-ion batteries. The studies aimed at enriching the fundamental understanding of the synthetic preparations, structural properties, and electrochemical functionality of these materials. By in situ synchrotron X-ray diffraction (XRD), the formation mechanism of the tavorite-type LiFeSO4F was followed starting from two different sets of precursors, FeSO4∙H2O + LiF, and Li2SO4 + FeF2. The results indicated that the formation of LiFeSO4F is possible only through the structurally related FeSO4∙H2O, in line with the generally recognized topotactic reaction mechanism. Moreover, an in-house solvothermal preparation of this polymorph was optimized with the combined use of XRD and Mössbauer spectroscopy (MS) to render phase pure and well-ordered samples. Additionally, the triplite-type LiFeSO4F was prepared using a facile high-energy ball milling procedure. The electrochemical performance of as-prepared tavorite LiFeSO4F was found to be severely restricted due to residual traces of the reaction medium (tetraethylene glycol (TEG)) on the surface of the synthesized particles. A significantly enhanced performance could be achieved by removing the TEG residues by thorough washing, and a subsequent application of an electronically conducting surface coating of p-doped PEDOT. The conducting polymer layer assisted the formation of a percolating network for efficient electron transport throughout the electrode, resulting in optimal redox behavior with low polarization and high capacity. In the preparation of cast electrodes suitable for use in commercial cells, reducing the electrode porosity was found to be a key parameter to obtain high-quality electrochemical performance. The triplite-type LiFeSO4F showed similar improvements upon PEDOT coating as the tavorite-type polymorph, but with lower capacity and less stable long-term cycling due to intrinsically sluggish kinetics and unfavorable particle morphology. Finally, the Li+-insertion/extraction process in tavorite LiFeSO4F was investigated. By thorough ex situ characterization of chemically and electrochemically prepared LixFeSO4F compositions (0≤x≤1), the formation of an intermediate phase, Li1/2FeSO4F, was identified for the first time. These findings helped redefine the (de)lithiation mechanism which occurs through two subsequent biphasic reactions, in contrast to a previously established single biphasic process.

An alternate family of “high” voltage (where the equilibrium voltage lies between 3.6 V and 4.2 V) polyanion cathode materials is reported in this thesis with the objective of improving specific energy density (Wh/kg) and developing a better understanding of polyanion electrochemistry. The electrochemical properties, synthesis and the structure of novel fluorosulfate materials crystallizing in the tavorite and the triplite type mineral structures are described. These materials display highest discharge voltages reported for any Fe2+/Fe3+ redox couple. LiFeSO4F was prepared in both the tavorite and the triplite polymorphs using inexpensive and scalable methods. Complete structural characterization was performed using X-ray and neutron based diffraction methods. A rapid synthesis of fluorosulfates can be achieved by using microwave heating. The local rapid heating created by the microwaves generates nanocrystalline LiFeSO4F tavorite with defects that induce significant microstrain. To date, this is unique to the microwave synthesis method. Phase transformation to the more stable triplite framework, facilitated by the lattice defects which include hydroxyl groups, is therefore easily triggered. The formation of nanocrystalline tavorite leads to nanocrystalline triplite, which greatly favors its electrochemical performance because of the inherently disordered nature of the triplite structure. Direct synthesis of the electrochemically active triplite type compound can be carried out either by extending the duration of the solvothermal reactions or by the partial substitution of Fe by Mn to produce LiFe1-xMnxSO4F. This study, overall, has led to a better understanding of the transformation of tavorite to the triplite phase. To examine Li and the Na ion conduction and their correlation with the electrochemical performance of 3-D, 2-D and 1-D ion conductors, atomistic scale simulations have been used to investigate tavorite type LiFeSO4F, NaFeSO4F, olivine type NaMPO4 (M= Fe, Mn, Fe0.5Mn0.5) and layered Na2FePO4F. These calculations predict high mobility of the Li-ion in the tavorite type LiFeSO4F but sluggish Na-ion transport in iso-structural NaFeSO4F. High mobility of the Na-ion is predicted for phosphate layered and olivine structures. Finally, the synthesis and structural details of NaMSO4F (M=Fe, Mn) and NH4MSO4F (M=Fe, Mn) are presented in the last chapter to show the structural diversity present in the fluorosulfate family.

This dissertation explores the interaction between literati and various social forces in east China in the mid-seventeenth century by focusing on their military performance. Based on a wide range of sources, the study focuses on about twenty literati, most of whom have never been previously researched from a military history perspective. It examines the diversity and complexity of Chinese literati as they pursued power over and within local society, paying special attention to the interrelation between them (literati and society). It argues that Chinese literati in this time period had much less aptitude in changing China than has been previously thought. Both individual and group case studies show that they mainly focused on the realization of an ideal goal, but were unwilling or ill-equipped to adapt themselves to changing conditions as well as environments. This study also indicates that the local military forces as well as ordinary peasants generally played a more crucial role than the literati; the latter's superior position could only be realized in times of peace. That civil and military officials affected each other in fact is an expression of a larger relationship between the central government and its own military forces or with certain local forces. Finally, this study concludes that Chinese literati as a whole had no idea how to integrate and lead the other social forces to reach an ideal goal in that specific time period.

NMR experiments performed under the effect of electric fields, either continuous or pulsed, can provide quantitative parameters related to ion association and ion transport in solution.  Electrophoretic NMR (eNMR) is based on a diffusion pulse-sequence with electric fields applied in the form of pulses. Magnetic field gradients enable the measurement of the electrophoretic mobility of charged species, a parameter that can be related to ionic association. The effective charge of the tetramethylammonium cation ion in water, dimethylsulphoxide (DMSO), acetonitrile, methanol and ethanol was estimated by eNMR and diffusion measurements and compared to the value predicted by the Debye-Hückel-Onsager limiting law. The difference between the predicted and measured effective charge was attributed to ion pairing which was found to be especially significant in ethanol. The association of a large set of cations to polyethylene oxide (PEO) in methanol, through the ion-dipole interaction, was quantified by eNMR. The trends found were in good agreement with the scarce data from other methods. Significant association was found for cations that have a surface charge density below a critical value. For short PEO chains, the charge per monomer was found to be significantly higher than for longer PEO chains when binding to the same cations. This was attributed to the high entropy cost required to rearrange a long chain in order to optimize the ion-dipole interactions with the cations. Moreover, it was suggested that short PEO chains may exhibit distinct binding modes in the presence of different cations, as supported by diffusion measurements, relaxation measurements and chemical shift data. The protonation state of a uranium (VI)-adenosine monophosphate (AMP) complex in aqueous solution was measured by eNMR in the alkaline pH range. The question whether or not specific oxygens in the ligand were protonated was resolved by considering the possible association of other species present in the solution to the complex. The methodology of eNMR was developed through the introduction of a new pulse-sequence which suppresses artifactual flow effects in highly conductive samples. In another experimental setup, using NMR imaging, a constant current was applied to a lithium ion (Li ion) battery model. Here, 7Li spin-echo imaging was used to probe the spin density in the electrolyte and thus visualize the development of Li+ concentration gradients. The Li+ transport number and salt diffusivity were obtained within an electrochemical transport model. The parameters obtained were in good agreement with data for similar electrolytes. The use of an alternative imaging method based on CTI (Constant Time Imaging) was explored and implemented. / <p>QC 20140825</p>

Les batteries, et en particulier les batteries lithium-ion (Li-ion), sont devenues des vecteurs de stockage de l'énergie particulièrement adaptés à l'avènement des très nombreuses applications portables (téléphones ou ordinateurs). Dans le but d'améliorer et de rendre plus sûrs ces vecteurs, il est impératif de pouvoir comprendre et caractériser de la manière la plus précise les matériaux les constituant et les interfaces les séparant. Pour cela, l'utilisation d'outils puissants et adaptés est essentielle, notamment depuis l'apparition de matériaux ayant une architecture à l'échelle nanométrique. Ainsi, l'utilisation de la Microscopie Electronique en Transmission (MET) est particulièrement prometteuse, pour sa capacité à analyser les propriétés morphologiques, structurales ou chimiques à cette échelle. Fort de ce constat, nous avons tenté de réaliser la première observation in situ dans un MET d'une batterie en cours de cyclage électrochimique. La première partie de ce manuscrit est dédiée à la présentation de la stratégie utilisée. En effet, les nombreuses difficultés liées à la fois à l'environnement du MET et à la nature même d'une batterie, nous ont forcé à faire des choix basés sur l'analyse de l'état de l'art, principalement en termes de matériaux, de technologies et d'équipements expérimentaux. Ainsi, ce projet est basé sur l'étude d'une microbatterie Li-ion tout solide. Le deuxième chapitre est lui consacré au procédé de fabrication par ablation laser de ces microbatteries tout solide, avec notamment la synthèse et la caractérisation de chacun des matériaux actifs constitutifs. La troisième partie décrit les solutions envisagées pour lever certaines des incertitudes qui avaient été identifiées. Nous avons ainsi réussi la première observation ex situ par MET d'une "nanobatteries" obtenue par découpe d'une microbatterie à l'aide d'un faisceau d'ions focalisés (FIB) dans un MEB à double faisceaux. Les analyses par MET entre des coupes de batteries après dépôt et ayant subi un cyclage électrochimique ont permis de mettre en évidence, pour la première fois, de nombreux dommages ou des mécanismes de détérioration des interfaces. Les premiers essais, et notamment la configuration utilisée, n'ayant pas permis de réaliser les premiers tests de cyclage in situ dans un MET, plusieurs modifications ont dû être opérées, qui sont présentées dans le dernier chapitre. Ce nouveau design a permis d'expérimenter un cyclage in situ sur des "nanobatteries" et de mettre en lumière les derniers challenges à relever.

L'objectif du travail décrit dans cette thèse est de développer des batteries Li-ion peu coûteuses, respectueuses de l'environnement, facilement industrialisables et recyclables, tout en utilisant des fibres cellulosiques et un procédé en milieu aqueux. Deux approches ont été adoptées pendant ce travail expérimental. Dans un premier temps, les microfibrilles de cellulose ont été utilisées pour la production d'anodes par un procédé de casting. Puis, une approche papetière a été adoptée. La plupart des travaux expérimentaux se sont focalisés sur l'utilisation de fibres de cellulose pour la production d'électrodes papier (anodes et cathodes) et de séparateurs-papier par procédé de filtration en milieu aqueux pour obtenir des cellules complètes à base de cellulose. Les électrodes obtenues sont homogènes, souples et leurs propriétés électrochimiques comparables à celles d'électrodes de références utilisant un polymère de synthèse comme liant.

Bakgrund. Kostens sammansättning får en stor betydelse för boende i Sverige då de inte tillgodogör sig D-vitamin från solen i samma utsträckning som länder vid ekvatorn, speciellt vintertid. Hela 80 % av den intagna mängden D-vitamin absorberas i tarmen, ändå visar forskning på att brist föreligger i större utsträckning bland boende över 55 breddgraden. Syfte. Studiens syfte var att undersöka hur troligt det är att boende i Sverige uppnår rekommenderat dagligt intag av D-vitamin. Metod. För att besvara syftet utfördes en internetbaserad kvantitativ studie, baserad på en frekvensenkät. Enkäten bestod av 28 frågor, varav åtta mätte intagsfrekvens av D-vitaminrika livsmedel. Urvalet baserades på ett bekvämlighetsurval. Kön, utbildningsnivå, hemort, utlandsvistelse, träning, kosttillskott- och solskyddsanvändning testades mot tre intagsgrupper baserad på intagen mängd D-vitamin med hjälp av Chit2-test. Vidare jämfördes deltagarnas intag mot EFSA´s gränsvärden. Resultat. Totalt inkom 144 enkätsvar av dessa rapporterade 93 % ett D-vitaminintag under rekommenderat dagligt intag (RDI). Beträffande livsmedel var lax, makrill, berikad lätt-/mellanmjölk och ägg de främsta källorna till deltagarnas uppskattade D-vitaminintag. Det var 21 % av respondenter som rapporterade ett intag under lower intake level (LI). Vidare rapporterade 32 % av respondenterna ett intag mellan LI och average requirement (AR). En mindre andel av respondenterna (n=20) hade varit utomlands under efterfrågad period. Majoriteten av respondenterna sågs använda solskyddsmedel, var aktiva och upplevde sig ha en god hälsa. Slutsats. Det beräknades föreligga en 53-% risk att någon av deltagarna hade ett inadekvat D-vitaminintag. Ett fåtal deltagare (n=10) beräknades inta D-vitamin i enlighet med RDI. / Background. The diet is of a great importance for residents in Sweden, since they do not assimilate vitamin D from the sun to the same extent as people living in countries located at the equator. The intestine absorbs as much as 80 % of the vitamin-D intake; nevertheless the insufficiency is more common among countries above the 55 latitude. Aim. The study aimed to investigate how likely it is that people in Sweden achieves the recommended daily intake of vitamin D. Method. To answer the question a quantitative study approach was chosen based on a non-random selection. Frequency questionnaire consisted of a total of 28 questions; eight measured the intake frequency of D- vitamin in food. Gender, education, place of residence, educational, training, food supplements and sun block use were tested against three intake groups based on vitamin D intake with Chit2 test. Later on participants' intake was compared with the limits of EFSA. Results. A total of 144 responded the survey, 93% of these reported a D-vitamin intake below the recommended daily intake (RDI). Food such as, salmon, mackerel, enriched easy- /semi-skimmed milk and eggs were principal sources of the participants' estimated D-vitamin intake. It was 21 % of respondents who reported an intake below lower intake level (LI). Furthermore, 32% of the respondents reported an intake between LI and average requirement (AR). A smaller proportion of the respondents (n= 20) had been abroad during requested period. The majority of the respondents were seen using sun block, was active and experienced to have a good health. Conclusion. It might be a 53-% risks that participants have an inadequate D-vitamin intake. A small number of participants (n= 10) estimate a vitamin D intake in accordance with RDI.