Orientador: Isabel Cristina Sales Fontes Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T10:34:05Z (GMT). No. of bitstreams: 1 Ferreira_ClaudiodeCastro_M.pdf: 1652977 bytes, checksum: b266745fcbc738cc97c41fdc4d79a00b (MD5) Previous issue date: 2014 / Resumo: / Resumo: Neste trabalho, prepararam-se fases estacionárias (FE) fluoradas capeadas para utilização em Cromatografia Líquida de Alta Eficiência em Fase Reversa (CLAE-FR). A preparação da FE consistiu na sorção do polímero poli(metil-3,3,3-trifluorproprilsiloxano) (PMTFS) sobre sílica, tipo B, com tamanho de partícula de 5 ?m, seguido de imobilização térmica a 226 oC, por 12 horas e extração com diclorometano, a fim de eliminar o polímero não aderido ao suporte. A FE imobilizada, Si(PMTFS), foi submetida à reação de capeamento com trimetilclorossilano e hexametildissilaxano, para a redução dos grupos silanóis que não foram recobertos pelo polímero. Testes físico-químicos e cromatográficos comprovaram a eficiência da imobilização do polímero e do capeamento. O desempenho cromatográfico da FE fluorada capeada, Si(PMTFS)ec, foi superior ao da não capeada e os testes de Tanaka e colaboradores demonstraram que o capeamento diminuiu a atividade silanofílica da FE e aumentou a sua hidrofobicidade. A FE Si(PMTFS)ec apresentou o mecanismo "U-shape", pois se observou o aumento da retenção de compostos básicos e polares em altas porcentagens do modificador orgânico na fase móvel. As FE de Si(PMTFS)ec apresentaram estabilidade química superior às FE não capeadas, porém, elas mostraram-se mais instáveis que as FE C8, C18 preparadas no grupo. Embora a estabilidade química à fase móvel em meio básica seja uma desvantagem, a mesma possui o mecanismo "U-shape" que pode ser utilizado para aumentar a retenção dos compostos básicos, sem o uso de condições drásticas de pH, além de ser uma FE mais apropriada quando se emprega o espectrômetro de massas, pois a alta concentração de solvente orgânico na fase móvel melhora a ionização dos analitos, aumentando as suas detectabilidades. A FE Si(PMTFS)ec constitui em uma alternativa bem sucedida para emprego em CLAE-FR, devido a sua capacidade em separar vários tipos de compostos / Abstract: / Abstract: In this work, end-capped fluorinated stationary phases (SP) for use in High-Performance Liquid Chromatography on Reversed Phase (RP-HPLC) were prepared. The preparation of the SP consisted in the sorption of the polymer poly(methyl-3,3,3-trifluorproprilsiloxane) (PMTFS) onto type B silica, with particle size of 5 µm, followed by thermal immobilization at 226 °C for 12 h and extraction with dichloromethane to eliminate the polymer that had not interacted with the support. The immobilized SP, Si (PMTFS), was subjected to an end-capping reaction to reduce the silanol groups that were not covered by the polymer. Physical-chemical and chromatographic tests were conducted to evaluate the efficiency of the immobilization of the polymer and of the end-capping reaction. The chromatographic performance of the end-capped fluorinated SP, Si (PMTFS)ec, was greater than that of the non-end-capped phase. The Tanaka tests showed a decrease in silanophilic activity and an increase in hydrophobicity. The Si (PMTFS)ec SP showed a U-shaped mechanism, because of the observed increase in retention of basic compounds at high percentages of the organic component in the mobile phase. The Si (PMTFS)ec SP showed superior chemical stability to non-end-capped SP, however, less stability than C8 and C-18 SP also prepared by the group. Although chemical stability in alkaline mobile phase is a disadvantage, it has a "U-shape" mechanism that can be used to increase the retention of basic compounds without the use of drastic conditions of pH, and is more appropriate for use with a mass spectrometer. Due to the high concentrations of organic solvent in the mobile phase the ionization of the analytes is better, increasing the detectability. The Si (PMTFS)ec SP can be used in RP-HPLC due to its ability to separate various types of compounds / Mestrado / Quimica Analitica / Mestre em Química

This dissertation consists of two studies, which respectively investigate L2 Chinese learners' acquisition of simple wh-questions of different grammatical functions longitudinally over their first-year learning and their acquisition of indirect questions and wh-questions in complements at the end of their first year. The participants consisted of 21 first-year English-speaking learners of Chinese. Both grammaticality judgment (GJ) and oral production (OP) tests were used. Study 1 reports that only attributive wh-questions posed more difficulty to the participants than object wh-questions in OP test at the beginning stage, and adverbial wh-questions and object wh-questions were not found to be significantly different to the participants as reported in some L1 and L2 studies. This author attributed this to the different syntactic mechanism that L2 learners of movement language and learners of in-situ language go through. The initial stage of participants' grammar did not display a clear presence of [+wh] feature strength, and the development of the [-wh] feature strength in learners' L2 grammar was not linear, but U-shaped. Study 2 reveals that learners' performance on indirect questions and wh-questions in object complements was not as good as their performance on simple wh-questions at the end of first year learning. For indirect questions, the initial stage of participants' L2 grammar showed an obvious L1 influence, the embedded [+wh]. For wh-questions in complements, it did not show an L1 influence, the matrix [+wh], but an embedded [+wh], which is non-target like but resembles wide-scope wh-questions with an embedded [+wh] in Malay and Madurese. Learners' performance on simple wh-questions patterned together with that in matrix clauses of wh-questions in complements, which was better than their performance on embedded clauses of the two types of complex wh-questions. Evidence for connection between their performance on simple wh-questions and matrix clauses of wh-questions in complements regarding the grammatical feature that wh-words are not allowed in clause initial position was revealed, but there was no strong evidence for connection between their performance on embedded clauses of the two types of complex wh-questions. It suggests that learners might be using different strategies for acquisition of structures of different natures.

Ultra Wide Band (UWB) is a short-pulse signal which has extremely potential in wireless communication system due to the advantages of high data rate, better immunity to multipath fading, wide bandwidth, and high capability. According to the Federal Communications Commission (F.C.C.), UWB only can be transmitted in short distance of a few to tens of meters due to low power density (-41.3dBm/MHz). However, optical fiber has low loss and cost and wide bandwidth, so it can be achieved in wide area network. In this work, we propose a novel method to generate optical UWB doublet pulse without complicated setup. When electroabsorption modulator (EAM) integrating a taper optical directional coupler (TODC) was applied field, the transmission loss and coupling would change resulting from the absorption coefficient and effective index of active waveguide with the applied field. So, we used a single mode fiber collecting the power after the device, we could get the valley shape transfer function. Using the transfer function of electro-absorption modulator (EAM) integrating TODC we inject a Gaussian pulse into the EAM in the range of valley shape, and it can transform an electrical pulse into optical UWB doublet pulse by acceptable operating point. Therefore, the optical signals could be transmitted in optical fiber so that it can reduce loss of the electro-optic transformation. Experimentally, the full wave at half maximum of doublet pulse, 10dB bandwidth, fractional bandwidth were 75ps, 7.5GHz, 125%, respectively, and power density was less than -41.3dBm/MHz. These were all meeting the F.C.C. standard. In the future, we will use long distant optical fiber to transmitted UWB signal, and compare with different distance. Finally, we will check the UWB signal can be transmitted in optical fiber to achieve wide range signal transmission by bit error rate test.

This study had three main purposes: (a) to determine whether there is a linear relationship between international undergraduate (IU) students' adaptation and time at Virginia Polytechnic Institute and State University (Virginia Tech), (b) to examine the effects of IU students' combined economic and linguistic backgrounds on their adaptation experience at Virginia Tech, (c) to determine the u-shaped curve model's effectiveness in explaining the adaptation experience of IU students from different backgrounds. The findings of this study could not be used to justify either a linear or a curvilinear relationship between time and IU students' adaptation. A difference in adaptation was found between IU students with two and four years at Virginia Tech based on their linguistic background differences, but no differences were found in regard to their economic background differences. A correlation analysis suggested a relationship between adaptation and the support IU students received while at Virginia Tech. Nevertheless, the most important finding is the fact that the existing models of IU students' adaptation do not adequately explain their adaptation experience. This study suggests that future research should concentrate on determining the relationship between IU students' adaptation and the adequacy of support they received. / Ph. D.

Over the last few decades, rechargeable lithium-ion batteries have been extensively used in portable instruments due to their high energy density and low self-discharge rate. Recently, lithium-ion batteries have emerged as the most promising candidate for electric vehicles and stationary energy storage. However, the maximum energy that lithium-ion batteries can store decreases as they are used because of various irreversible degradation mechanisms. Lithium-ion batteries are complex systems to understand, and various processes and their interactions are responsible for the degradation over time. The mechanical integrity and stability of the electrode layers inside the battery highly influence the battery performance, which makes it a necessity to characterize the mechanical behavior of electrode active layers for mesoscopic and macroscopic level modeling. In papers 1 and 2, the macroscopic mechanical behavior of active layers in the electrodes is investigated using U-shape bending tests. The active layers are porous and a different tensile and compressive behavior is captured by performing tests on single side coated dry specimens. The experiments reveal that the active layer is stiffer in compression as compared to tension. The compressive stiffness increases with bending strain whereas the tensile stiffness is almost independent of the bending strain. A very low value of modulus of the active layer (1-5 GPa) is measured in comparison to the metal foils (70-110 GPa) and the active particles (50-200 GPa) which shows that the electrode properties are governed majorly by the binders present in the active layers.  The time-dependent and hysteresis effects are also captured by the method which circumvents the flaws of many other test methods presented in the literature.   In paper 3, we present a multiscale homogenization method that couples mechanics and electrochemistry at the particle, electrode, and battery scales. The active materials of lithium-ion battery electrodes exhibit volume change during lithium intercalation or deintercalation. A lithium concentration gradient develops inside particles, as well as inside the active layer. The developed stress due to deformations further affects solid diffusion.  We utilized models that have already been developed to couple particle and electrode layer levels. The mechanical coupling between the electrode and the battery level is achieved by homogenization of the layered battery using three-dimensional laminate theory.  By application of the model, we demonstrate that the stresses on all considered scales can be predicted from the homogenized model. It is furthermore demonstrated that the effects of external battery loadings like battery stacks, casings, and external pressure can be captured by the model. The model can also capture the effect of various electrochemical cycling rates and mechanical parameters like layer thicknesses, stiffnesses, and swelling properties. The presented multi-scale model is fast, accurate and the efficiency of the method is demonstrated by comparisons to detailed finite element computations where each layer is individually modeled.

金融商品的價格變動是投資人用以判斷獲利與否的重要工具，因為價格變動不易精確預測，所以常利用其他變數輔助預測價格變動，其中以交易量最常被投資人用來分析價格變動。本文是利用台灣首檔指數型股票基金「台灣50指數股票型基金，簡稱TTT」，分析基金的價格變動與交易量之間的關係。 由於TTT具有「實物申購╱買回」機制，當TTT發生折溢價現象時，投資者會利用此機制進行策略性的投資。因此，「實物申購╱買回」機制使用，會對TTT交易量產生影響，並且使得基金淨值與價格更為貼進。所以本文也將分析TTT折溢價與交易量之間的關係。 本研究利用Granger因果關係理論檢測變數之間的因果關係，實證結果發現，TTT的交易量與價格變動呈現雙向因果關係，且折溢價對於交易量具有單向因果關係，即折溢價可以解釋和預測交易量變動，並且折溢價偏離的現象在半天之內會消失。因此，歸論「實物申購╱買回」機制能有效發揮其作用。 / This study examines intraday patterns of the Taiwan Top 50 Tracker Fund (TTT), with special emphasis on the causal relationship between trading volume and return, and the causal relationship between trading volume and deviation ratio. We find strong intraday seasonality, namely the W-shaped trading pattern which appeared to be caused by the so-called lunch-break effect. After accounting for this apparent seasonality, and by employing the Granger causality test, we find that there is a causal bi-direction relationship between trading volume and absolute return. However, there only exists a uni-directional causal relationship from the deviation ratio to trading volume, but not vice versa. Also, the deviation is disappeared within half day.