Orientador: René Alfonso Nome Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T06:54:35Z (GMT). No. of bitstreams: 1 Dantas_WillianFranciscoCordeiro_M.pdf: 2446830 bytes, checksum: a6ef77a86d65956736e20e7c5e22ff59 (MD5) Previous issue date: 2015 / Resumo: A espectroscopia vibracional de femtossegundos da vizinhança é ideal para caracterizar os movimentos moleculares da vizinhança acoplados com o sistema eletrônico captador de luz. No caso dos movimentos nucleares intramoleculares, isto pode ser realizado tanto por infravermelho quanto por Raman, ambos de femtossegundos. No caso de movimentos intermoleculares, a dinâmica de femtossegundos somente pode ser caracterizada com experimento Raman coerente, e, por essa razão, é importante sabermos qual é o comportamento do clorofórmio em um experimento de femtossegundo. Dessa forma, pode-se realizar a comparação entre os dados experimentais e teóricos e concluir se o comportamento observado experimentalmente é o mesmo que o esperado. Este trabalho explora a análise de Franck-Condon para os espectros de emissão do pireno com dependência da temperatura. Assume-se que uma progressão vibrônica de bandas no formato de Lorenzianas pode representar o formato das bandas de emissão do fluoróforo. Consequentemente, é possível obter alguns parâmetros, como a largura de linha das bandas obtidas, as intensidades relativas dos picos observados (valores que são utilizados para encontrar os fatores de Huang-Rhys), a variação do comprimento de onda de emissão com o aumento da temperatura e a área integrada dos espectros / Abstract: The femtosecond vibrational spectroscopy of the neighborhood is ideal to characterize the molecular movements of the neighborhood coupled with the electronics pickup light. In the case of intra-molecular nuclear movements, this can be accomplished either by infrared and Raman both femtosecond. In the case of intermolecular movements, the dynamics of femtosecond can only be characterized with coherent Raman experiment, and so it is important to know the behavior of chloroform in a femtosecond experiment. Thus, it is possible to make a comparison between experimental and theoretical data and conclude that the observed experimentally is the same behavior expected. This work explores the Franck-Condon analysis for the emission spectra of pyrene in dependence on temperature. It is assumed that a vibronic bands in the progression Lorenzianas shape may represent the format of fluorophore emission bands. Consequently, it is possible to obtain some parameters such as the line width of the bands obtained, the relative intensities of the observed peaks (values that are used to find the Huang-Rhys factors), the variation of emission wavelength with increasing temperature and the integrated area of the spectra / Mestrado / Físico-Química / Mestre em Química

Orientadores: Eduardo Granado Monteiro da Silva, Fernando Iikawa / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-28T03:52:30Z (GMT). No. of bitstreams: 1 Ardito_FabioMachado1984-_D.pdf: 17276184 bytes, checksum: 26e823f6c84e2068348c69f11dbd1424 (MD5) Previous issue date: 2015 / Resumo: O célebre efeito Hall quântico semi-inteiro no grafeno é uma consequência direta dos níveis de Landau característicos previstos pela equação de Dirac. Apesar de se saber que os níveis de Landau devam ser tão estreitos quanto possível para que os efeitos de mecânica quântica relativística sejam realçados, pouca informação sobre os mecanismos mais relevantes que levam ao alargamento destes níveis em grafeno está disponível atualmente. Nesta tese, experimentos de micro-Raman a baixas temperaturas e campos magnéticos de até 15~T foram feitos em tipos diferentes de amostras de grafeno: monocamadas e bicamadas depositadas sobre um substrato de Si/SiO$_2$; e multicamadas produzidas sobre SiC. As larguras das transições interbanda entre níveis de Landau são obtidas pela análise do amortecimento das ressonâncias magneto-fônon que ocorrem quando transições opticamente ativas entre níveis de Landau cruzam a energia do fônon E$_{2g}$. A partir de uma análise quantitativa das larguras dependentes do índice de cada transição, encontramos que amostras produzidas por meios distintos mostram mecanismos de alargamento de níveis de Landau amplamente diferentes. O alargamento na amostra com multicamadas é causado por uma distribuição nas velocidades de Fermi ($\delta v_F \sim 8.7\times10^4$~m/s) possivelmente devida a flutuações residuais nas interações entre camadas, enquanto o alargamento em monocamadas é devido, principalmente, à presença de pseudo-campos magnéticos ($\delta B_{strain}=1.7$~T para nossa amostra) criados por tensões na rede através de interações com o substrato. A busca por métodos de fabricação de grafeno com qualidade eletrônica superior precisa levar em conta estes dois tipos de mecanismos de alargamento / Abstract: The famous half-integer quantum hall effect in graphene is a direct consequence of the characteristic Landau levels predicted by the Dirac equation. Albeit minimal Landau level widths are mandatory to reinforce the relativistic quantum effects under low magnetic fields, little information on the most relevant mechanisms leading to Landau level broadening in graphene samples is presently available. In this thesis, micro-Raman experiments at low temperatures and fields up to 15 T were performed on distinct graphene samples, namely a natural single-layer and a bilayer graphene flake deposited over a Si/SiO$_2$ substrate; and a multilayer epitaxial graphene sample produced on SiC. The interband Landau level transition widths are obtained by an analysis of the damping of the magnetophonon resonances that occur when optically active Landau level transitions cross the energy of the $E_{2g}$ phonon. We find, by means of a quantitative analysis of the index-dependent Landau level transition widths, that graphene samples produced by such distinct routes show largely different dominant Landau level broadening mechanisms. In fact, the broadening in multilayer epitaxial graphene is caused by a distribution of Fermi velocities ($\delta v_F \sim 8.7\times10^4$~m/s), possibly due to fluctuations of residual interlayer graphene interactions, while the Landau level broadening in single-layer graphene is mainly due to the presence of random strain-induced pseudo-magnetic fields ($\delta B_{strain}=1.7$ T for our sample) caused by interactions with the substrate. Search for production methods of graphene with optimal electronic quality must take into account both possible Landau level broadening mechanisms / Doutorado / Física / Doutor em Ciências / CAPES

Orientadores: Eduardo Granado Monteiro da Silva, Gaston Eduardo Barberis / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T00:28:16Z (GMT). No. of bitstreams: 1 Silva_DaniloRigitanoGomes_M.pdf: 3482148 bytes, checksum: b0e5e19407a3aa53a6a788e88a435a94 (MD5) Previous issue date: 2016 / Resumo: LiNiPO4 é um isolante antiferromagnético com spins (S=1) de íons Ni 2+ localizados e um alto acoplamento magnetoelétrico abaixo de T N =20,8K. Medidas de espalhamento Raman polarizado em monocristais dessa estrutura ortorrômbica mostram, além do espectro de fônons, um sinal característico a valores baixos de número de onda (<100cm -1 ), que são independentes de campo magnético aplicado ao longo da direção do eixo a. Em polarização X(ZZ)-X, este sinal pode ser bem modelado pela teoria de Fleury-Loudon de espalhamento Raman por dois mágnons e usando um Hamiltoniano de Heisenberg com parâmetros de troca dos cinco primeiros íons vizinhos e dois de anisotropia. Essas constantes foram refinadas usando nossos dados de espalhamento Raman com dados previamente publicados de espalhamento inelástico de nêutron (INS, Jensen et al., Phys. Rev. B 79, 092413 (2009)) por um procedimento de fitting de simulated annealing, sendo consistentes com os parâmetros extraídos exclusivamente das medidas de INS. Em polarização X(ZY)-X, dois outros picos foram observados na fase de estado magneticamente ordenado, não atribuíveis a espalhamento por dois mágnons. Medidas similares de espectroscopia Raman foram realizadas para LiCoPO 4 mas o sinal obtido foi insuficiente para identificar a contribuição advinda das excitações magnéticas / Abstract: LiNiPO4 is an antiferromagnetic insulator with localized Ni 2+ spins (S=1) and large magnetoelectric coupling below T N =20.8K. Polarized Raman scattering experiments in a single crystal with ortorhombic structure show, besides the phonon spectra, extra features at low wavenumbers (<100cm -1 ) below T N , which are independent of applied magnetic fields along a-direction. In X(ZZ)-X polarization, this signal could be well modeled by the Fleury-Loudon theory of two-magnon Raman scattering, using a Heisenberg Hamiltonian with five nearest-neighbor exchange and two anisotropy parameters. These constants were refined using our Raman-scattering data and previously published inelastic neutron scattering data (INS, Jensen et al., Phys. Rev. B 79, 092413 (2009)) through a simulated annealing fitting procedure, being consistent to parameters extracted using INS data alone. In X(YZ)-X polarization, two extra peaks are observed in the magnetically ordered state, not attributable to two-magnon scattering. Similar measurements were taken for LiCoPO 4 , however the observed signal was insufficient to identify the contribution from magnetic excitations / Mestrado / Física / Mestre em Física / 1372841/2014 / CAPES

Técnicas espectroscópicas vibracionais Raman e infravermelho foram utilizadas no estudo conformacional de algumas proteínas de interesse biológico, no que se refere a aspectos estruturais de seus esqueletos polipeptídicos e microambientes de cadeias laterais de certos resíduos de aminoácidos. O trabalho foi dividido em dois grupos, de acordo com os sistemas em estudo: a) Toxina &#947; do veneno de escorpião brasileiro Tityus serrulatus. A análise vibracional revelou que o esqueleto polipeptídico dessa proteína consiste de diferentes estruturas secundárias, com predominância de folhas &#946;, seguida por estruturas do tipo não regular e &#945;-hélice, com alguma evidência de dobras &#946;. Conformação gauche-gauche-gauche foi detectada para os segmentos CCSSCC das quatro pontes dissulfeto. A intensidade do dubleto Raman da Tyr a 853 e 828 cm-1 indicou que 4 dentre 5 resíduos de Tyr encontram-se expostos na superficie molecular. Também há indicações de que os 3 resíduos de Trp apresentem localização externa. Sob o ponto de vista qualitativo, as características conformacionais da toxina no estado sólido amorfo e em solução são virtualmente as mesmas. b) Fosfolipases A2 de pâncreas de porco e de Crotalus durissus terrificus. Mudanças confarmacionais foram detectadas para as moléculas de fosfolipase como consequência de diferentes condições experimentais tais como mudança de estado físico, presença de certas espécies iônicas e interação com um análogo de substrato e com o próprio substrato. Características conformacionais discrepantes foram observadas para a forma sólida amorfa e forma cristalina da fosfolipase pancreática. Transições conformacionais foram detectadas para a transformação zimogênio &#8594; fosfolipase A2 e diferentes conteúdos estruturais foram calculados para a forma tóxica e atóxica dessa enzima. Todas essas mudanças conformacionais envolveram basicamente a arquitetura do esqueleto polipeptídico, não afetando a conformação das cadeias laterais dos resíduos de amino ácidos. As pontes dissulfeto apresentaram consistentemente uma conformação ggg a qual não foi perturbada por nenhuma das condições experimentais empregadas. A ocorrência externa de resíduos de triptofano constituiu uma característica comum para os sistemas ensaiados, assim como a localização predominante de residuos de tirosina em microambientes hidrofílicos, provavelmente na superficie molecular. / Raman and infrared spectroscopies were used to investigate conformational features of some proteins of biological interest, in what concerns structural aspects of their polypeptide backbones and microenvironments of certains amino acid residue side-chains. The work has been divided in two groups as related to the systems studied: a) Toxin &#947; from the venom of Brazilian scorpion Tityus serrulatus. The vibrational analysis has revealed that the protein polypeptide backbone consists of different secondary structures, with predominance of &#946;-sheet, followed by unordered structure and &#945;-helix, with some evidence of &#946;-turns. A gauche-gauche-gauche (ggg) conformation for the CCSSCC fragments of the four dissulfide bridges has been detected. The intensity of the Tyr Raman doublet at 853 and 828 cm-1 indicated that 4 out of the 5 Tyr residues are exposed at the molecular surface. External localization of the 3 Trp residues has also been indicated. Under a qualitative point of view, conformational features of the toxin the amorphous solid state and in solution were virtually the same. B) Crotalus durissus terrificus and porcine pancreatic phospholipases A2. Conformational changes were detected for the phospholipases molecules as a consequence of different conditions such as change of physical state, presence of certain ionic species and interaction with a model substrate analog and with the substrate itself. Amorphous and crystalline solid pancreatic phospholipases presented discrepant conformational features. Conformational transitions were detected for the pancreatic zymogen &#8594; phospholipase A2 transformation and different secondary structures contents were observed for the toxic and the non toxic phospholipase melecules. All those structural changes heve been shown to involve primarily the architecture of the polypeptide backbone rather than the conformation of amino acid residue side-chains. Disulfide bridges have shown consistently a ggg conformation which has not been disturbed by any of the experimental conditions employed. The external occurrence of tryptophan residues has been a common feature for the systems assayed, as well as the predominant localization of tyrosine residues in hydrophylic environments, probably at the molecular surface.

Submitted by Jakeline Ortega (jakortega@unoeste.br) on 2018-09-21T20:10:17Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Viviane Ribas Pereira PDF.pdf: 2053033 bytes, checksum: 480912202f53c9af07d7ace2942faf4f (MD5) / Made available in DSpace on 2018-09-21T20:10:17Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Viviane Ribas Pereira PDF.pdf: 2053033 bytes, checksum: 480912202f53c9af07d7ace2942faf4f (MD5) Previous issue date: 2018-04-14 / Difenoconazole, a fungicide of the triazoles group, is widely used during the cultivation of passion fruit, orange, strawberry, papaya and other crops. Respiratory return and in the public health space, as it can affect the population through the consumption of contaminated food. Thus, the present study was evaluated as an experimental challenge on sperm quality, from an experimental model. For this, Wistar males (45 days) were divided into 4 experimental groups (n = 10 / group): control and exposed to 5 (DA), 10 (DB) and 50 (DC) mg / kg / day of diphenoconazole, via gavage for 30 consecutive days. During the exposure period, the animals were followed for clinical signs of toxicity, water and feed intake and body weight. Throughout this period, the reproductive organs, liver and kidneys were collected and weighed. Spermatozoa were submitted to evaluation of motility, morphology, vitality, acrosome and Surface Enhanced Raman Spectroscopy (SERS). The testis and epididymis were scaled for sperm counts. For the original network learning test, the Bayes classifier (BAY), K-Nearest Neighbors (K-NN) and Support Vector Machine (SVM). The results were compared by ANOVA with Tukey posterior test, and the Kruskall-Wallis test with Dunn a posteriori, considering p <0.05. Body weight and reproductive organs, liver and culture are not altered during exposure to the fungicide. The progressive motility, the acrosomal membrane and the percentage of spermatozoa were the variables used in the variables DB and DC in relation to the joint control. Already vitality was only doubled in the DC group. In addition, sperm indices were not tested and were reduced in the three groups exposed. SERS measurements resulted in changes in the sperm bands of the DC group in relation to the control. The computational analysis identified the presence of a standard for the experimental groups with good classification in the SVM test (≥ 80% accuracy). Thus, the exposure of Wistar rats to doses of the difenoconazole fungicide may be reduced by reducing the sperm quality, with the classification pattern of exposure groups. / O difenoconazol, um fungicida do grupo dos triazóis, é amplamente utilizado durante o cultivo de maracujá, laranja, morango, mamão e em outras culturas. Sua intensa utilização traz preocupações ambientais e no âmbito da saúde pública, visto que, pode afetar a população através do consumo de alimentos contaminados. Desta forma, o objetivo do presente estudo foi avaliar os efeitos da exposição ao difenoconazol sobre a qualidade espermática, de um modelo experimental. Para isso, foram utilizados ratos machos Wistar (45 dias) divididos em 4 grupos experimentais (n=10/grupo): controle e expostos a 5 (DA), 10 (DB) e 50 (DC) mg/kg/dia de difenoconazol, via gavagem por 30 dias consecutivos. Durante o período de exposição, os animais foram acompanhados em relação aos sinais clínicos de toxicidade, consumo de água e ração e peso corpóreo. Ao término deste período, os órgãos reprodutivos, fígado e rins foram coletados e pesados. Os espermatozoides foram submetidos à avaliação da motilidade, morfologia, vitalidade, integridade acrossomal e análise de Espectroscopia de Espalhamento Raman Amplificado em Superfície (SERS). O testículo e o epidídimo direito foram coletados para as contagens espermáticas. Para o teste de aprendizado de máquina foram utilizados quatro algoritmos de reconhecimento de padrões: Artificial Neural Network (ANN), Bayes Classifier (BAY), K-Nearest Neighbors (K-NN) e Support Vector Machine (SVM). Os resultados foram comparados por ANOVA com o teste “a posteriori” de Tukey, e o teste de Kruskall-Wallis, com “a posteriori” de Dunn, considerando p<0,05. O peso corpóreo e dos órgãos reprodutivos, fígado e rins não sofreram alterações significativas após a exposição ao fungicida. A motilidade progressiva, a integridade da membrana acrossomal e a porcentagem de espermatozoides morfologicamente normais foram reduzidas nos grupos DB e DC em relação ao grupo controle. Já a vitalidade foi reduzida apenas no grupo DC. Além disso, os números de espermatozoides no testículo e no segmento cabeça/corpo do epidídimo e a produção diária de espermatozoides foram reduzidos nos três grupos expostos. As medidas de SERS mostraram alterações nas bandas dos espectros dos espermatozoides do grupo DC em relação ao controle. A análise computacional identificou a presença de um padrão para os grupos experimentais com boa classificação no teste SVM (≥ 80% de acurácia). Assim, concluiu-se que a exposição de ratos Wistar a diferentes doses do fungicida difenoconazol pode reduzir a qualidade espermática, com reconhecível padrão de classificação de grupos de exposição.

Brain tumors or brain cancer is a disease than affects people of all ages. The median age of a person living with a brain tumor is 60 years, it is however a disease that affects children and young adults in high grade. Brain cancer is the second most common type of cancer among children and is also the most common cause of cancer related death among this group. To ensure that the damages on the brain is as small as possible, it is important that a tumor can be diagnosed and removed as early as possible. Previous methods of diagnosis is based on biopsy where a part of the tumor is removed and examinated by a pathologist. This is a time consuming process that also is biased by the human factor, there is therefore a need for a method that can be used \textit{in situ} with an unbiased result. One method that have shown great promise is photensitation with 5-Aminolevoluic acid (5-ALA). However, this method have shown to only work properly on tumors of high malignancy in adults. As a comlpiment to photosentisation, Raman spectroscopy have shown good promise in previous studies.  This study was conducted to investigate the use of Raman spectroscopy as a tool for \textit{in situ} brain tumor diagnostics. The use of Raman spectroscopy was tested by comparing two previously performed studies, where they looked at a number of Raman bands from biological markers that are known to change in cancerous tissue as well as the intensity ratio between some Raman bands.  A measurement system for Raman spectroscopy was designed and built at Luleå University of Technology where the system were evaluated on tissue samples from conventional meat i.e. pork and beef to ensure that is was possible to achieve spectroscopic information of protein and lipid content in tissue. The measurement system was then transported to Linköpings University where the measurements on six brain tissue samples where performed. The samples came from five different tumors of which one tumor was thought to come from a high malignant tumor based on preliminary histopathological analysis and four from low malignant or benign tumors. Two samples where obtained from the high malignant tumor that was photosentisized with 5-Aminolevoluic acid and one of the samples where illuminated with blue light prior to the Raman spectroscopic measurements.  The spectroscopic data was pre-processed before analysis using conventional methods. The analysed spectra from the brain tissue samples showed presence of the Raman bands associated with brain tissue. It was also possible to see Raman bands associated with 5-ALA in the samples that had been photosentisized, however when the tissue had been illuminated with blue light it was also possible to see distinct Raman bands associated with brain tissue. One tissue sample also showed presence of reduced Neuroglobin (NGB). The composition of NGB is also known to change in tumorous tissue and could therefore be used in future work as a biological marker for brain tumors. When comparing the results obtained in this study with the two previously performed, one of the studies showed that two samples were from a tumor of high malignancy and the other from low malignant or benign tumors. This result was in accordance with the preliminary histopathological assessment of the brain tissue samples. When comparing the results to the other study, the results where contradictory and indicated that all tissue samples where from low malignant or benign tumors.  The conclusion of this work is that Raman spectroscopy is possible to use as a tool for brain tumor diagnostics. It would be desirable to use this method in combination with 5-ALA staining since the Raman bands from brain tissue could be resolved when the tissue had been illuminated with blue light. / Hjärntumörer kan drabba människor i alla åldrar, medelåldern för människor som lever med en hjärntumör är 60 år, men det är ett tillstånd som även drabbar barn och unga i stor utsträckning. Hjärntumörer är den näst vanligaste cancerformen hos barn och är även den främsta orsaken till cancerrelaterad död i den åldergruppen. För att minimera skadorna på hjärnan är det viktigt att en tumör kan lokaliseras och tas bort så tidigt som möjligt. De metoder som används idag bygger framför allt på biopsi, där en del av tumören tas bort och undersöks av en histopatalog. Det är en process som tar lång tid och även påverkas av den mänskliga faktorn, det finns därmed ett behov av en metod som kan avändas \textit{in situ} som ger ett resultat som inte påverkas av den mänskliga faktorn. En metod som har visat lovande resultat är fotosensibilisering med 5-Aminolevulinsyra (5-ALA). Desvärre har den metoden bara visat sig fungera bra för högmaligna tumörer hos vuxna. Som ett komplement till fotosensibilisering har Ramanspektroskopi visat lovande resultat i tidigare genomförda studier.  Det här arbetet genomfördes för att undersöka användningen av Ramanspektroskopi som ett verktyg för diagnostisering av hjärntumörer. Som grund användes två tidigare genomförda studier där de undersökte Ramanband från biologiska markörer i hjärnvävnad som ändras i cancerogen vävnad. De undersökte även hur den biokemiska sammansättningen av hjärnvävnaden ändrades genom att jämföra intensiteten av olika Ramanband.  Ett mätsystem för Ramanspektroskopi designades och byggdes upp på Luleå Tekniska Universitet där det även testades på vävnad från kött (fläsk och biff). Därefter transporterades mätsystemet till Linköpings Universitet för att genomföra mätningar på sex olika vävnadsprov från fem hjärntumörer av olika malignitet. Baserat på en preliminär histopatalogisk bedömning var en av tumörerna högmalignt och de fyra andra tumörerna var antingen lågmalignta eller benigna. Två av proverna som undersöktes kom från den högmalignta tumören som även var fotosensibilierad med 5-Aminolevulinsyra, varav ett av proverna var belyst med blått ljus innan de Ramanspektroskopiska mätningarna genomfördes.  Innan resultatet från Ramanspektroskopiska mätningarna analyserades behandlades datan med konventionella metoder i MatLab. I de resulterade spektrumen gick det att se tydliga Ramanband associerade med hjärnvävnad. Det gick även att se Ramanband associerade med 5-ALA i de två prover som var fotosensibiliserade och i det provet som var belyst med blått ljus innan de spektroskopiska mätningarna gjordes gick det även att se tydliga Ramanband associerade med hjärnvävnad. När resultatet analyserades gick det även att se spektra associerat med reducerat Neuroglobin (NGB) i ett av proverna. Sammansättningen av NGB är också någonting som ändras i cancerogen vävnad och skulle därför också kunna användas som en bilogisk markör för hjärntumörer i framtida studier.  När resultaten från den här studien jämfördes med de tidigare studierna indikerade den ena studien att två av vävnadsproverna kom från en högmalignt tumör och att de resterande fyra från lågmaligna eller benigna tumörer, vilket stämmer överens med den preliminära diagnosticeringen av tumörerna. När resultatet istället jämfördes med den andra studien stämde inte resultatet lika bra med den preliminära diagnosticeringen av tumörerna. Metoden presenterad av Zhou m.fl. indikerade att alla tumörer kom från lågmaligna eller benigna tumörer.  Slutsaten av det här arbetet är att Ramanspektroskopi skulle kunna användas som en metod för diagnosticering av hjärntumörer. Metoden skulle även fungera bra som ett komplement till fotosensibilisering med 5-ALA eftersom att det var möjligt att se Ramanband associerade med hjärnvävnad när vävnaden hade belysts med blått ljus.

Gold nanoparticles produced using the Turkevich method were able to have their hydrophobicity modified using octanethiol in a novel method for SERS application. Both amphiliphic GNPs and hydrophobic GNPs were produced and differentiated by Raman signals. The amphiliphic GNPs were able to enhance the SERS signals of the protein emulsifier in the emulsion in situ and the hydrophobic GNPs were able to enhance the SERS signals from canola oil. Further purification of the hydrophobic GNPs proved to have higher enhancement and sensitivity, but still poor consistency which is typical of SERS. Monitoring lipid oxidation using Raman and SERS using alternative approaches was the primary objective of the thesis. The purified GNPs were capable of enhancing the canola oil over two weeks, but the poor consistency led to no major trends. Using normal Raman, a triphenylphosphine oxidation reaction was capable of producing a peroxide value correlation in a very simple and rapid manor. Using a gold nanoparticle modified stainless steel wire, the headspace volatiles from canola oil oxidation were able to be enhanced, but with poor consistency. Silver dendrites were used to enhance the canola oil signal but with poor resolution. A combination of silver dendrites and GNPs were used to slightly improve enhancement, but not as strong as GNPs alone.

京都大学 / 新制・論文博士 / 博士(工学) / 乙第13407号 / 論工博第4193号 / 新制||工||1762(附属図書館) / (主査)教授 安部 武志, 教授 作花 哲夫, 教授 阿部 竜 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Fabrication of carbon infiltrated carbon nanotubes (CI-CNT) can result in large mechanical property variation, and methods to characterize properties usually involve destructive testing. Finding a non-destructive way to test for stiffness of this material reduces the number of parts that have to be made. It also simplifies testing of complex parts. The stiffness of CI-CNT beams is related to the type of carbon material infiltrated between the carbon nanotubes (CNTs), how it interacts with the CNTs, and how much of it there is. The amount of material can be estimated using the density of the beam, and both the type of material and its interaction with the carbon nanotubes can be approximated through analysis of the Raman spectra taken at the surface. A combination of these two observations can be related to the effective material stiffness. The relationship can be fitted with a power function, with a variance of 1.41 GPa, which is about 11% of the maximum stiffness of the samples tested. This variance is similar to the larger variations in CI-CNT beam stiffnesses found in a single batch of beams.

The evolution of electronics has become the staple thrust of modern scientific innovation: a need for advancing materials engineered for our equally rapidly advancing needs and computing requirements has fueled recent wealth of new materials. Here, I use the ideals of exotic materials design to answer this need, specifically for 2D materials. Two-dimensional (2D) van der Waals materials with in-plane anisotropy are of great interest for directional transport of charge and energy. I perform solid state synthesis to produce several such materials: an intrinsic antiferromagnet, superatomic semiconductors, and a polytype system with a component that displays the possibilities of Weyl nodes.The former, chromium sulfur bromide (CrSBr), is first synthesized, then fully studied structurally, compositionally, electronically, and magnetically. Second harmonic generation (SHG), more advanced than older techniques such as magneto-optical Kerr spectroscopy or Raman spectroscopy, allows us to fully understand the magnetic symmetry in this system as an interlayer antiferromagnetic and intralayer ferromagnetic in-plane anisotropic material. I also introduce published work in which we integrate CrSBr into different devices to show the utility of this fundamental research into a more practical application setting. It is used to stimulate more magnetic response from graphene — promising ultra-thin magnetic memory or sensory devices in future projects. Applying strain and external magnetic fields provides another tuning knob through which to access different functional modalities. In the latter third of this dissertation, we report a layered van der Waals semiconductor with in-plane anisotropy built upon the superatomic units of Mo₆S₃Br₆ (MSB), a robust construction with a direct gap of 1.64 eV. Next, MSB and Re₆Se₈Cl₂, another analogous superatomic vdW material, are potential candidates for optoelectronic applications; we qualify this by studying their Auger dynamics as a measure of quantum efficiency. Finally, layered van der Waals (vdW) materials belonging to the MM’Te₄ structure class have recently received intense attention due to their ability to host exotic electronic transport phenomena, such as in-plane transport anisotropy, Weyl nodes, and superconductivity. In summary, we have discovered two ternary exfoliatable vdW TMD polytypes with the composition TaFeTe₄, one of which (ꞵ) shows the prerequisite symmetry elements to be a type-II Weyl semimetal. This dissertation is a treatise to solid state synthesis, exploration into the more exotic spectrum of 2D materials, and robust and eclectic methods used to paint a full picture of different magnetic and electronic systems within.