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Holt, Jim, and Gregg Mitchell. "SAMS Work Group—Preventive Care." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/6466.
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Prompinit, Panida. "Formation and application of photo-patterned SAMs." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539684.
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Yousefalhaj, Nisreen. "Molecular engineering of azidoorganosilane-based SAMs for bioapplications." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0317.
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La capacité à contrôler les propriétés de surface et à réaliser l’ingénierie moléculaire de SAMs est déterminant pour permettre une immobilisation contrôlée des biomolécules, ce qui est d'une importance majeure pour le développement de nombreuses applications dans le domaine de la biologie. Dans ce travail, nous présentons d'abord la synthèse de différents types d'agents de couplage utilisés pour fournir deux types de SAM à terminaison azoture : portant un espaceur alkyle ou un espaceur urée de différentes longueurs. Ensuite, nous présentons en détail le dépôt des SAMs en utilisant différentes méthodes et stratégies dans différents solvants. Chaque changement a été étudié en profondeur pour étudier son effet sur la matière organique dans les SAMs et l'orientation des azotures, ainsi que la réactivité du groupe azido vis-à-vis de la réaction de clic CuAAC. Les modifications chimiques des surfaces ont été étudiées par les mesures PM-IRRAS, XPS, AFM et d'angle de contact. Ainsi, ce travail se termine par une liste relativement longue de SAMs bien définies à terminaison azoture, ce qui en fait de bons candidats pour diverses applications dans le domaine de la biologie. Certains des SAMs à terminaison azoture ont été utilisées avec succès pour immobiliser les GNL. La quantité de GNL varie à la surface en fonction de la nature des SAMs et de la quantité de groupes azotures. Cette plateforme montre des résultats prometteurs lorsqu'elle est testée pour la culture de cellules souchesThe ability to control surface properties and produce molecularly engineered SAMs is the key aspect for a precise biomolecules immobilisation in a preferred manner, which is of major importance for the development of many bioapplications. In this work, we provide first the novel synthesis of different types of coupling agents used to provide two types of azide-terminated SAMs: bearing an alkyl spacer or a urea spacer of different lengths. Then, we present in details the deposition of SAMs by using different methods and strategies in different solvents. Each change has been deeply studied to investigate its effect on the organic matter within the SAMs and the azide orientation, as well as the reactivity of the azido group towards the click reactions (CuAAC). The chemical modifications of the surfaces have been investigated by the PM-IRRAS, XPS, AFM and the contact angle measurements. Thus, this work ends up with a relatively big list of well-defined azide-terminated SAMs, as good candidates for various bioapplications. Some of azide-terminated SAMs have been successfully used to immobilise GNLs, resulting in differences of immobilised GNLs quantity on the surface depending on the nature of SAMs and the quantity of azide groups. This platform shows promising results when tested for stem cells culture
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Cheadle, Edward Martin. "Characterisation of self-assembled monolayers." Thesis, University of Leeds, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250878.
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Ribeiro, Luisa Maria Fialho. "Qualidade dos cuidados de enfermagem no hospital dos SAMS." Master's thesis, [s.n.], 2012. http://hdl.handle.net/10400.26/16142.
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Mestrado, Enfermagem de Saúde Infantil e Pediatria, 2012, Escola Superior de Enfermagem de LisboaNa identificação que o Plano Nacional de Saúde 2012-2016 faz da situação atual quanto à qualidade em saúde, e à semelhança do Plano anterior, identifica uma escassa cultura de qualidade associada a um défice organizacional dos serviços de saúde, assim como a falta de indicadores de desempenho e de apoio à decisão. A implementação de sistemas de melhoria contínua da qualidade torna-se assim fundamental. Com a qualidade enquanto core de uma organização de saúde, cabe ao enfermeiro chefe, enquanto gestor de enfermagem, munir-se dos instrumentos adequados e incrementar estratégias favorecedoras de um melhor nível de desempenho e responsabilidade profissional, com direta repercussão nos ganhos em saúde resultantes do cuidado de enfermagem. Objetivo: Com a realização deste Projeto de Intervenção pretendeu-se desencadear a implementação de um Sistema de Melhoria Contínua da Qualidade no Departamento de Cirurgia do Hospital dos SAMS. Metodologia: Para a consecução do presente trabalho, socorremo-nos da Metodologia de Trabalho de Projeto, e de um documento produzido pela Ordem dos Enfermeiros em 2010, - Regulamento da Idoneidade Formativa dos Contextos de Prática Clínica, que compreende sete dimensões de análise, à luz do qual foi feita a análise das práticas do Departamento de Cirurgia do Hospital dos SAMS. Da aplicação do referido documento, resultou uma grelha – grelha de análise – na qual, são evidenciadas as dimensões suscetíveis de intervenção. Resultados: Ao nível organizacional, foi envolvida a gestão de topo (Enfermeiro Supervisor), no sentido da necessidade de conceber um documento ancorador das práticas de enfermagem. Sustentados na literatura; no coaching obtido de instituições análogas e, ainda, em documentação interna, foi desenvolvido o Quadro de Referência para o Hospital dos SAMS. Ao nível departamental, destacamos a realização do Quadro de Referência para o Departamento; mobilização da equipa para desenvolver e ampliar o âmbito da avaliação da qualidade dos cuidados a outros indicadores (Dor; Satisfação do Utente; Incidente Críticos); nomeação do Enfermeiro Responsável pela Formação em Serviço e do Enfermeiro de ligação ao PQCE, que se traduziu na realização de diversas formações, designadamente, no âmbito do PQCE e dos indicadores de qualidade anteriormente mencionados. Conclusões: Em termos gerais, a concretização do presente projeto, foi bastante proveitosa na medida em que, por um lado, despertou a gestão de topo para as questões da qualidade dos cuidados associadas às práticas de enfermagem. De outro, ao nível do departamento, possibilitou a reflexão da equipa sobre as práticas, tendo a mesma constituindo-se como móbil de alargamento do âmbito de intervenção a outras dimensões consideradas pertinentes, designadamente, enquadradas no PQCE e, ao nível das parcerias com as Escolas Superiores de Enfermagem/Saúde. Ao nível pessoal e enquanto gestora da Unidade de Saúde, a consecução deste projeto facilitou o desenvolvimento de “novas competências” que, associadas à motivação, se traduziram num olhar “mais crítico” acerca do nosso contexto profissional, impelindo-nos a intervir e mobilizar recursos no sentido de operar mudança numa área que nos preocupa muito – Qualidade dos Cuidados. Terminamos sublinhando o carácter desenvolvimentista e reformador da metodologia de trabalho de projeto, como ferramenta de intervenção nos contextos de trabalho.
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Leonardi, Francesca <1986>. "Self-Assembled Monolayers (SAMs) in Organic Field-Effect Transistors." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6461/1/Leonardi__dottorato.pdf.
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Organic printed electronics is attracting an ever-growing interest in the last decades because of its impressive breakthroughs concerning the chemical design of π-conjugated materials and their processing. This has an impact on novel applications, such as flexible-large-area displays, low- cost printable circuits, plastic solar cells and lab-on-a-chip devices.
The organic field-effect transistor (OFET) relies on a thin film of organic semiconductor that bridges source and drain electrodes. Since its first discovery in the 80s, intensive research activities were deployed in order to control the chemico-physical properties of these electronic devices and consequently their charge. Self-assembled monolayers (SAMs) are a versatile tool for tuning the properties of metallic, semi-conducting, and insulating surfaces. Within this context, OFETs represent reliable instruments for measuring the electrical properties of the SAMs in a Metal/SAM/OS junction.
Our experimental approach, named Charge Injection Organic-Gauge (CIOG), uses OTFT in a charge-injection controlled regime. The CIOG sensitivity has been extensively demonstrated on different homologous self-assembling molecules that differ in either chain length or in anchor/terminal group.
One of the latest applications of organic electronics is the so-called “bio-electronics” that makes use of electronic devices to encompass interests of the medical science, such as biosensors, biotransducers etc…
As a result, thee second part of this thesis deals with the realization of an electronic transducer based on an Organic Field-Effect Transistor operating in aqueous media. Here, the conventional bottom gate/bottom contact configuration is replaced by top gate architecture with the electrolyte that ensures electrical contact between the top gold electrode and the semiconductor layer. This configuration is named Electrolyte-Gated Field-Effect Transistor (EGOFET).
The functionalization of the top electrode is the sensing core of the device allowing the detection of dopamine as well as of protein biomarkers with ultra-low sensitivity.
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Leonardi, Francesca <1986>. "Self-Assembled Monolayers (SAMs) in Organic Field-Effect Transistors." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6461/.
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Organic printed electronics is attracting an ever-growing interest in the last decades because of its impressive breakthroughs concerning the chemical design of π-conjugated materials and their processing. This has an impact on novel applications, such as flexible-large-area displays, low- cost printable circuits, plastic solar cells and lab-on-a-chip devices.
The organic field-effect transistor (OFET) relies on a thin film of organic semiconductor that bridges source and drain electrodes. Since its first discovery in the 80s, intensive research activities were deployed in order to control the chemico-physical properties of these electronic devices and consequently their charge. Self-assembled monolayers (SAMs) are a versatile tool for tuning the properties of metallic, semi-conducting, and insulating surfaces. Within this context, OFETs represent reliable instruments for measuring the electrical properties of the SAMs in a Metal/SAM/OS junction.
Our experimental approach, named Charge Injection Organic-Gauge (CIOG), uses OTFT in a charge-injection controlled regime. The CIOG sensitivity has been extensively demonstrated on different homologous self-assembling molecules that differ in either chain length or in anchor/terminal group.
One of the latest applications of organic electronics is the so-called “bio-electronics” that makes use of electronic devices to encompass interests of the medical science, such as biosensors, biotransducers etc…
As a result, thee second part of this thesis deals with the realization of an electronic transducer based on an Organic Field-Effect Transistor operating in aqueous media. Here, the conventional bottom gate/bottom contact configuration is replaced by top gate architecture with the electrolyte that ensures electrical contact between the top gold electrode and the semiconductor layer. This configuration is named Electrolyte-Gated Field-Effect Transistor (EGOFET).
The functionalization of the top electrode is the sensing core of the device allowing the detection of dopamine as well as of protein biomarkers with ultra-low sensitivity.
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Pardo-Figuerez, Maria M. "Designing neuronal networks with chemically modified substrates : an improved approach to conventional in vitro neural systems." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/27941.
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Highly organised structures have been well-known to be part of the complex neuronal network presented in the nervous system, where thousands of neuronal connections are arranged to give rise to critical physiological functions. Conventional in vitro culture methods are useful to represent simplistic neuronal behaviour, however, the lack of such organisation results in random and uncontrolled neurite spreading, leading to a lack of cell directionality and in turn, resulting in inaccurate neuronal in vitro models. Neurons are highly specialised cells, known to be greatly dependent on interactions with their surroundings. Therefore, when surface material is modified, drastic changes in neuronal behaviour can be achieved. The use of chemically modified surfaces in vitro has opened new avenues in cell culture, where the chaotic environment found in conventional culture methods can be controlled by the combination of surface modification methods with surface engineering techniques. Polymer brushes and self-assembled monolayers (SAMs) display a wide range of advantages as a surface modification tool for cell culture applications, since their properties can be finely tuned to promote or inhibit cellular adhesion, differentiation and proliferation. Therefore, when precisely combined with patterning techniques, a control over neuronal behaviour can be achieved. Neuronal patterning presents a system with instructive cues that can be used to study neuron-neuron communication by directing single neurites in specific locations to initiate synapses. Furthermore, although this area has not been much explored, the use of these patterned brushes could also be used in co-culture systems as a platform to closely monitor cell heterotypical communication. This research demonstrates the behaviour of SH-SY5Y neurons on a variety of SAMs and polymer brushes, both in isolation and combination to promote cellular spatial control. APTES and BIBB coatings promoted the highest cell viability, proliferation, metabolic activity and neuronal maturation, whilst low cell adhesion was seen on PKSPMA and PMETAC surfaces. Thereafter, PKSPMA brushes were used as a potential cell repulsive coating and its combination with micro- patterning techniques (photolithography and soft lithography) resulted in a system with instructive cues for neuronal guidance, where neuronal directionality was obtained. In the final chapter of this thesis, a chimeric co-culture system was developed where the patterned SH-SY5Y cells were co-cultured with C2C12 myoblasts in an attempt to obtain an organised neuronal-muscle co-culture system. Whilst preliminary observations showed first stages of a patterned neuronal-muscle co-culture, future work is necessary to refine and improve the patterned co-culture process.
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Pukenas, Laurynas. "Fabrication and characterisation of SAMs for spin crossover and photocleavable surfaces." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16602/.
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This thesis investigates self-assembled monolayers (SAMs) of molecules of various complexity with a special focus on fabrication of surfaces that could exhibit an intrinsic active function, more precisely a capability to switch between two stable states upon external stimuli (spin crossover phenomenon) or to expose functional groups upon irradiation with light, i.e. photocleavage of a SAM. SAM formation of a complex novel molecule, lipoic acid ester of α-hydroxy-1-acetyl-pyrene (reagent 1), was studied in chapter 3. It contains i) a dithiolane headgroup capable of binding to gold surfaces via two sulfur atoms, and ii) a chromophore that makes it light sensitive (photocleavable) and leads to a deprotection of lipoic acid molecule upon exposure to soft UV (365nm). Reagent 1 successfully forms SAM1, but it interacts with the gold surface weaker than conventional thiol based SAMs, due to cross-linking of dithiolane headgroups. Nevertheless, SAM1 is a relatively stable monolayer and exerts a higher barrier against diffusion of copper ions towards gold surface in electrochemical deposition than SAMs of similarly complex molecules but with thiol headgroups or shorter alkanethiol SAMs terminated with carboxylic acid groups (COOH). SAM1 undergoes photolysis upon soft UV (365nm) irradiation, but only in the acidic catalyst 100mM HCl in isopropanol (IPA). Unexpectedly, this also leads to a removal of the resulting lipoic acid monolayer, thus ultimately leading to SAM1 with lower surface coverage, and changes packing and ordering. SAMs of alkanethiols terminated with COOH and of varying chain length were investigated in order to better understand the cause for the instability of lipoic acid monolayer. Loss of molecules from the surfaces was found to be a common issue in the COOH SAMs, however, the severity of the loss is strongly related to the initial SAM thickness. Thin SAMs like DTBA SAM yield huge (∼50%) loss, while thick SAMs like MUA SAM show no detectable loss. On the other hand, photo-patterned SAM1 produces especially high selectivity of Cu deposition between UV treated and non-treated regions, which is associated to this loss of surface coverage, packing and ordering. Surprisingly, reagent 1 also interacts with glass and silicon oxide surfaces to form hydrophobic films that exhibit green fluorescence under soft UV light. Such surfaces are photo-sensitive and can be photo-patterned in the air or in the acidic catalyst to produce non-fluorescent hydrophilic regions due to photo-bleaching of pyrene groups and photo-deprotection of lipoic acid molecules, respectively. The films and patterns stored under ambient conditions are detectable for at least 35 days. Formation of those films is associated with an interaction of pyrene group with adsorbates on the surfaces, while film growth is attributed to the cross-linking of dithiolane headgroups. SAM fabrication of metal complexes was explored in chapter 4. Two novel ligands L1 and L2, and their corresponding Fe(II) complexes C1 and C2, which can exhibit spin crossover (SCO) behaviour in bulk, were investigated. Both ligands successfully form SAMs. However, SAM L1 does not coordinate Fe(II), while its preformed complex C1 is not stable on Au surface and forms SAM L1 instead of SAM C1. In contrast, SAM L2 coordinates Fe(II) at nearly 100% yield, which leads to almost the same chemical composition as in a SAM of its preformed Fe(II) complex C2 (SAM C2). Although complex C2 with MeCN as the sixth exogenous ligand (SEL) exhibits low spin (LS) state in bulk at room temperature, only high spin (HS) state was detected in SAM C2. Complex C2 exhibits a unique property of changing its spins state in certain solvents, because a solvent molecule can easily displace the sixth exogenous ligand (SEL). However, rinsing SAM C2 with such solvents did not lead to a spin transition, and LS state was never observed for the SAM. This implies that the strength of the ligand field may need to be increased or SEL with a higher affinity coordinated to complex C2, in order to change the spin state by rinsing or to detect SCO in SAM C2. A long-chain alkanethiololigoethyleneglycol (LCAT-OEG) type molecule terminated with the azide group (reagent 2) was investigated for the facilitation of click chemistry on gold surfaces (chapter 5). Reagent 2 forms a good quality SAM (SAM2), and the concentration of reagent 2 in the SAM can be reduced in a controlled and predictable manner by the addition of LCAT-OEG-1 or LCAT-OEG-4 to the growth solution. QCMD measurements indicate that the whole surface of SAM2 successfully undergoes click reaction with cycloalkyne in aqueous solution without any catalyst. Finally, simple alkanethiol and aromatic type SAMs were investigated for use in surface-enhanced Raman spectroscopy (SERS) with nanoparticle-on-mirror configuration and for studying plasmonic systems, due to their ability to yield optimum precision over the control of thickness and dielectric function (chapter 5).
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Bonin, Helena. "Fremde Kinder und ideologische Staatsapparate : Wie Momo, Pippi und das Sams Ideologie entgehen." Thesis, Högskolan Dalarna, Tyska, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-29356.
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Ideology, as explained by Louis Althusser, is used by ideological state apparatuses (ISAs) to reinforce the control of the dominant class. ISAs in turn consist of elements of society such as families, schools, and churches. In the works of Michael Ende, Astrid Lindgren, and Paul Maars, Momo, Pippi and the Sams defy the ideologies and norms of their respective societies. This thesis shows that the three children can do this because they are alien children and therefore exist beyond the reach of the ISAs of their respective worlds.
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Graybill, Elizabeth A. "Age, Origin and Mineral Resources of the Sams Creek/Wakefield Complex, Maryland Piedmont." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1337975457.
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Wang, Lian. "Synthesis and Characterization of Functionalized Bio-Molecular Surfaces with Self-Assembled Monolayers and Bioreactive Ligands for Nano/Biotechnological Applications." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195096.
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In this work, the synthesis and characterization of functionalized biosurfaces that can be used for bioseparations and bio-nanotechnology are reported. A novel protein purification technique that incorporates chelating ligands and polymers onto the same chromatographic matrix is explored. A polysaccharide based gel, agarose, was modified systematically with hybrid ligands of the chelator iminodiacetic acid (IDA) and the polymer polyethylene glycol (PEG). The PEG molecule acts as a blocking polymer that can allow only small proteins to permeate onto the matrix surfaces and form conventional immobilized metal ion affinity chromatographic (IMAC) interactions with the chelators. Kinetic studies of chelator and polymer attachment were performed in order to effectively control the chelator and polymer densities on the matrix. Studies with different PEG surface densities and their effects on the adsorption of several proteins (e.g. myoglobin, lysozyme and bovine serum albumin (BSA)) were evaluated to characterize these new hybrid size exclusion IMAC (SEIMAC) matrices. An exclusion effect was observed while adsorption as observed in IMAC systems took place.Functionalization schemes and procedures were extended in the activation and incorporation of affinity ligands on inorganic surfaces such as gold surfaces. Functional gold platforms were explored for development of nano-interconnects via functionalized self assembled monolayers (FSAMs) on gold to attach specific affinity ligands as linkers to immobilize biomolecules, such as microtubules (MTs). MTs eventually could be utilized as self assembling structures and templates for fabrication of nano-scale bio-interconnect arrays and networks. In this work, different organothiols were used to form FSAMs and anti-glutathione S-transferase was attached as a linker to utilize the attachment of MT cap proteins, gamma-tubulin. The gamma-tubulin could recognize specifically a heterodimer of the MTs and can provide a nucleation center for MT growth. Several methodologies were employed including photolithographic methods and the use of photoreactive compounds for proper micro/nano scale dual protein functionalization of surfaces with homogeneous affinity ligands and with heterogeneous ligands as well.
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Marchante, Rodríguez Elena. "Self-assembled monolayers of electroactive molecules for the preparation of memory devices." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/406091.
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El objetivo fundamental de los circuitos eléctricos es la miniaturización utilizando moléculas, de manera individual o el conjunto de ellas, como bloques de construcción electrónicos. Se espera que el pequeño tamaño de los componentes electrónicos reduzca el consumo de energía a la vez que aumente la sensibilidad y el rendimiento del dispositivo.
Los esfuerzos que se hacen en investigación están orientados en dos direcciones: la primera está enfocada en el estudio, a nivel fundamental, de nuevas moléculas con propiedades o funcionalidades específicas, que proporcionan un conocimiento más profundo de la estructura molecular, dinámica y reactividad. El segundo se dedica al desarrollo de nuevas técnicas para la implementación de estas moléculas in dispositivos electrónicos.
A menudo, para fabricar un dispositivo molecular se necesita depositar las moléculas o materiales en un sustrato adecuado. Es importante controlar cómo afecta el disolvente, el sustrato o la funcionalización molecular en el ensamblaje molecular final y las interacciones moleculares, ya que el ordenamiento y el empaquetamiento de las moléculas son aspectos clave para el funcionamiento de los dispositivos.
Esta Tesis Doctoral está enfocada en el desarrollo de nuevos dispositivos moleculares electrónicos basados en monocapas auto-ensambladas de moléculas electroactivas, y en el estudio electroquímico de los procesos de transferencia electrónica asociados a ellos. En la primera parte de la Tesis, se describe el uso de diferentes moléculas redox inmovilizadas en sustratos de oro como interruptores moleculares. El estado de los compuestos electroactivos se puede modular aplicando un potencial específico sobre el sustrato, y se ha implementado satisfactoriamente la respuesta en capacitancia como señal de salida del interruptor. Es importante destacar que se han obtenido estos interruptores moleculares eléctricos usando también geles iónicos como electrolitos sólidos, demostrando la viabilidad de integrar estos sistemas en futuros dispositivos electrónicos y/o flexibles.
En la segunda parte de la Tesis, se presenta el estudio del mecanismo de transferencia electrónica, por medios electroquímicos, en una familia de compuestos derivados de radicales de policlorotrifenilmetilos (PTM), enlazados a sustratos de oro. La familia de moléculas de PTM contiene un grupo tiol en el extremo conectado al PTM a través de una cadena alquílica de distintas longitudes. Se ha estudiado el proceso de transferencia electrónica a través de SAMs de PTM en distintos medios electrolíticos y en función del grado de recubrimiento de la superficie del sustrato de oro modificado. Por lo tanto, se ha demostrado que la interacción de los disolventes juega un papel importante en el carácter adiabático del proceso redox. Además, el acoplamiento electrónico entre centros de moléculas de PTM adyacentes favorece la disminución de la constante de transferencia electrónica.
Finalmente, en la última parte de la Tesis, se han fabricado transistores orgánicos de efecto campo (OFETs) utilizando un gel iónico como material dieléctrico, y se han estudiado sus propiedades. Los OFET se fabricaron con geometrías tipo “top-gate” y “side-gate”, donde el gel iónico se colocó encima del sustrato con el canal semiconductor. Las propiedades de estos transistores con gel iónico se compararon con estructuras similares como referencia, las cuales están basadas en oxido de silicio convencional, resultando ser bastante interesantes para aplicarlos en transistores orgánicos flexibles y económicos.The ultimate goal of electrical circuits is miniaturization by using single molecules or collections of single molecules as electronic building blocks. It is expected that the smaller size of the electronic components will decrease the power consumption while increasing the sensitivity and the performance of the device. Research efforts are concentrated in two directions. The first one is focused in the study, at a fundamental level, of new molecules with specific properties or functionalities, which provides a deeper understanding of molecular structure, dynamics and reactivity. The second one is dedicated to develop new techniques for the implementation of these molecules in electronic devices. Often, to construct a molecular device it is necessary to deposit molecules or material on a suitable substrate. Since the ordering and packing of the molecules are crucial aspects for the operation of the devices, it is important to have a good control of how solvent, substrate or molecular functionalization influences on the resulting molecular assemblies and the intermolecular interactions. The present Doctoral Thesis is focused on the development of new molecular electronic devices based on electroactive self-assembled monolayers (SAMs), and on the electrochemical study of the electron transfer phenomena associated to them. In the first part of the Thesis, it is described the use of different redox molecules immobilized on gold substrates as molecular switches. The state of the electroactive compounds can be tuned when a specific potential is applied to the substrate, and the capacitance response has been successfully implemented as the read-out of the switch. It is important to highlight that these electrical molecular switches have been also obtained using ion gels as solid electrolytes, demonstrating the feasibility to integrate these systems in future electronic and/or flexible devices. In the second part of the Thesis, it is reported the electron transfer (ET) mechanism study, by electrochemical means, in a family of polychlorothriphenylmethyl radical (PTM) derivative compounds attached to gold substrates. The family of PTM molecules contains a thiol terminal group connected to the PTM through an alkyl chain with different lengths. It has been studied the ET process through PTM-SAMs in different organic electrolytic media and as a function of the surface coverage of the modified gold substrate. Hence, it was demonstrated that the interaction with the solvent plays an important role in the adiabaticity character of the redox process. Further, with neighbouring molecules, the intermolecular electronic coupling between PTM centers promotes a reduction of the ET constant rate. Finally, in the last part of the thesis, it has been fabricated a functioning OFET using an ion gel as gate dielectric, and its properties has been examined. The OFETs were prepared with top-gate and side-gate geometries, where the ion gel was placed on top of the substrate with the semiconductor channel. The ion gel gated OFET properties were compared with a reference OFET structure, which had a conventional SiO2 gate dielectric, demonstrating that the ion gels are highly attractive to be applied in low cost and flexible organic transistors.
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Hou, Lin, Jaber Derakhshandeh, Silvia Armini, Carine Gerets, Preter Inge De, Rebibis Kenneth June, Andy Miller, wolf Ingrid De, and Eric Beyne. "SAMs (self-assembled monolayers) passivation of cobalt microbumps for 3D stacking of Si chips." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-207172.
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In this paper SAM (self-assembled monolayers) is used to passivate cobalt microbumps for 3D-stacking of Si chips. The SAM deposition process is optimized, using input from characterization techniques such as water contact angle measurement, ATR, AFM and XPS analysis in order to form a monolayer of Thiols-SAM on cobalt microbumps. A 3D stacked Si chips test vehicle was used to demonstrate the effectiveness of the SAM coating on cobalt bumps by measuring the electrical continuity of daisy chains.
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Pinheiro, Solange de Oliveira. "Sintese , caracterizaÃÃo e eletroatividade de sams formadas com compostos catiÃnicos de tetraaminas de rutÃnio." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1460.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorOs complexos trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+ (CNpy = 4-Cianopiridina, 1,4- dt = 1,4-ditiano), trans-[Ru(CNpy)(NH3)4(pyS)]2+ (pyS = 4-mercaptopiridina) e trans- [Ru(CNpy)(NH3)4(Tio)]2+ (Tio = tionicotinamida) foram sintetizados e caracterizados por Cromatografia LÃquida de Alta EficiÃncia, anÃlise elementar, eletroquÃmica e espectroscopias eletrÃnica e vibracional. Os espectros de absorÃÃo eletrÃnica e os resultados de eletroquÃmica evidenciaram uma interaÃÃo do tipo π back-bonding do centro metÃlico RuII para os ligantes piridÃnicos. Os valores dos potenciais formais de meia onda (E1/2) observados para os complexos trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+, trans-[Ru(CNpy)(NH3)4(pyS)]2+ e trans-[Ru(CNpy)(NH3)4(Tio)]2+: 1,00, 0,67 e 1,03 V vs ENH, respectivamente, indicam a estabilizaÃÃo do estado reduzido do centro metÃlico em relaÃÃo ao complexo de partida trans-[Ru(CNpy)(NH3)4(OH2)]2+ (E1/2 = 0,35 V vs ENH). Esse resultado indica, tambÃm, a forte capacidade π retiradora do ligante CNpy que, no caso do complexo trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+, à tÃo intensa que facilita comparativamente o processo de oxidaÃÃo do centro metÃlico. Podese concluir, portanto, que a capacidade π retiradora dos ligantes CNpy, pyS e Tio à similar. O deslocamento na freqÃÃncia de estiramento da ligaÃÃo C≡N do ligante Cnpy livre de 2239 para ∼2200 cm-1 apÃs coordenaÃÃo ao centro metÃlico [Ru(NH3)4]2+ nos espectros vibracionais indica que a coordenaÃÃo do ligante CNpy ocorre pelo grupamento nitrila. Para os ligantes pyS e Tio, a observaÃÃo das bandas atribuÃdas aos νC=S e νSH, respectivamente, indica que a coordenaÃÃo ocorre pelo Ãtomo de nitrogÃnio do anel piridÃnico. Os espectros SERS ex situ das superfÃcies modificadas com os compostos isolados permitem a classificaÃÃo destes como molÃculas modificadoras bifuncionais, onde o Ãtomo de enxofre dos ligantes pyS, 1,4-dt e Tio atuam como sÃtio de adsorÃÃo e o Ãtomo de nitrogÃnio piridÃnico do ligante CNpy atua como grupo funcional terminal. AlÃm disso, os resultados SERS sugerem uma conformaÃÃo trans para o complexo trans-[Ru(CNpy)(NH3)4(pyS)]2+ e gauche para os complexos trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+ e trans-[Ru(CNpy)(NH3)4(Tio)]2+ sobre ouro. A dependÃncia nas intensidades das bandas com o potencial aplicado aos eletrodos modificados ilustra o efeito π back-bonding dos Ãons metÃlicos dos adsorbatos inorgÃnicos, uma vez que observa-se uma relaÃÃo direta com os valores dos potenciais formais de meia onda dos complexos estudados. Os valores dos potenciais de dessorÃÃo redutiva observados para as SAMs dos complexos isolados refletem a capacidade π retiradora do ligante CNpy que se encontra na posiÃÃo para em relaÃÃo ao sÃtio de adsorÃÃo. Esse efeito à bem mais intenso no complexo trans- [Ru(CNpy)(NH3)4(1,4-dt)]2+, uma vez que a capacidade de interaÃÃo π back-bonding do ligante 1,4-dt à significativamente menor que as dos ligantes pyS e Tio. Sugere-se, para esse complexo, uma oxidaÃÃo parcial do centro metÃlico o que implica em uma intensificaÃÃo da interaÃÃo σ com o ligante 1,4-dt (RuII-S) e, conseqÃentemente, um enfraquecimento da ligaÃÃo Au-S. A reaÃÃo hTE da metaloproteÃna cyt c foi observada em valor consistente com seu estado in natura indicando que as SAMs estudadas acessam satisfatoriamente o processo hTE do cyt c alÃm de evitar a desnaturaÃÃo desta proteÃna. A forma das curvas voltamÃtricas, entretanto, apresentou uma dependÃncia com a configuraÃÃo dos complexos sobre a superfÃcie. Curvas de melhor definiÃÃo foram obtidas com a SAM do complexo trans-[Ru(CNpy)(NH3)4(pyS)]2+ que apresenta uma configuraÃÃo trans em relaÃÃo à superfÃcie.
Trans-[Ru(CNpy)(NH3)4(L)]2+ type complexes, where CNpy (4- Cyanopyridine), L= 1,4-dt (1,4-dithiane), pyS (4-mercaptopyridine), and Tio (thionicotinamide), were synthesized and characterized by HPLC, microanalysis, eletrochemistry and vibrational and eletronic spectroscopies. The eletrochemical and eletronic absorption results are indicative of a π back-bonding interaction, L(nπ*) ← RuII(dπ) for which L is the pyS, CNpy and Tio ligands. The half-wave formal potentials (E1/2) observed for the trans-[Ru(CNpy)(NH3)4(pyS)]2+, trans- [Ru(CNpy)(NH3)4(1,4-dt)]2+ and trans-[Ru(CNpy)(NH3)4(Tio)]2+ complexes: 1.00, 0.67 and 1.03 V vs NHE, respectively, are indicative of the stabilization of the metal in the reduced state comparatively to the start complex, trans-[Ru(CNpy)(NH3)4(OH2)]2+ (E1/2 = 0.35 V vs NHE). This result indicates, also, the strong π withdraw capability of the CNpy ligand. The shift observed for the νC≡N mode from 2239 cm-1 in the vibrational spectra of the CNpy free ligand to ∼2200 cm-1 upon coordination suggests that the coordination occurs through the nitrile fragment. For the pyS and Tio ligands, the observation of the signals assigned to the νC=S and νSH modes, respectively, in the vibrational spectra os the complexes indicates that the coordination occurs through the nitrogen atom os the pyridine ring. The SERS ex situ spectra of the gold surfaces modified with the isolated complexes allow the classification of these species as binfunctional molecules in which the sulfur atom of the pyS, 1,4-dt and Tio ligands is the adsorption site and the nitrogen atom of the CNpy pyridine ring is the functional terminal group. Also, the SERS results point for a trans conformation for the trans- [Ru(CNpy)(NH3)4(pyS)]2+ complex and for a gauche configuration for the trans- [Ru(CNpy)(NH3)4(1,4-dt)]2+ and trans-[Ru(CNpy)(NH3)4(Tio)]2+ complexes on gold. The intensity dependence of some signals in the SERS spectra with the applie potential reflects the π back-bonding effect on surface since this behavior is observed to be strongly related to the E1/2 values of the complexes. The reductive desorption potentials of the SAMs formed with the isolated compounds reflects the π withdraw capability of the CNpy ligand. This effect is much more intense for the trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+ complex since the π back-bonding interaction of the 1,4-dt ligand is lower than the CNpy, pyS and Tio ligands. The heterogeneous electron transfer reaction of the cytochrome c metalloprotein was satisfactorily assessed with the SAMs formed by the isolated complexes (E1/2 = 0.05 V vs Ag⏐AgCl⏐Cl-). The Best voltammetric response was observed with the SAM of the trans- [Ru(CNpy)(NH3)4(pyS)]2+ complex due to the trans conformation on surface.
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Pinheiro, Solange de Oliveira. "Sintese , caracterização e eletroatividade de sams formadas com compostos catiônicos de tetraaminas de rutênio." reponame:Repositório Institucional da UFC, 2006. http://www.repositorio.ufc.br/handle/riufc/13712.
Full textAbstract:
PINHEIRO, S. O.; DIÓGENES, I. C. N. Sintese , caracterização e eletroatividade de sams formadas com compostos catiônicos de tetraaminas de rutênio. 2006. 116 f. Dissertação (Mestrado em Química Orgânica) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2006.Submitted by José Jairo Viana de Sousa (jairo@ufc.br) on 2014-10-15T17:44:28Z No. of bitstreams: 1 2006_dis_sopinheiro.pdf: 2241358 bytes, checksum: 0dea1c8d56ba429bd77cc89b4b868d66 (MD5)
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Trans-[Ru(CNpy)(NH3)4(L)]2+ type complexes, where CNpy (4- Cyanopyridine), L= 1,4-dt (1,4-dithiane), pyS (4-mercaptopyridine), and Tio (thionicotinamide), were synthesized and characterized by HPLC, microanalysis, eletrochemistry and vibrational and eletronic spectroscopies. The eletrochemical and eletronic absorption results are indicative of a π back-bonding interaction, L(nπ*) ← RuII(dπ) for which L is the pyS, CNpy and Tio ligands. The half-wave formal potentials (E1/2) observed for the trans-[Ru(CNpy)(NH3)4(pyS)]2+, trans- [Ru(CNpy)(NH3)4(1,4-dt)]2+ and trans-[Ru(CNpy)(NH3)4(Tio)]2+ complexes: 1.00, 0.67 and 1.03 V vs NHE, respectively, are indicative of the stabilization of the metal in the reduced state comparatively to the start complex, trans-[Ru(CNpy)(NH3)4(OH2)]2+ (E1/2 = 0.35 V vs NHE). This result indicates, also, the strong π withdraw capability of the CNpy ligand. The shift observed for the νC≡N mode from 2239 cm-1 in the vibrational spectra of the CNpy free ligand to ∼2200 cm-1 upon coordination suggests that the coordination occurs through the nitrile fragment. For the pyS and Tio ligands, the observation of the signals assigned to the νC=S and νSH modes, respectively, in the vibrational spectra os the complexes indicates that the coordination occurs through the nitrogen atom os the pyridine ring. The SERS ex situ spectra of the gold surfaces modified with the isolated complexes allow the classification of these species as binfunctional molecules in which the sulfur atom of the pyS, 1,4-dt and Tio ligands is the adsorption site and the nitrogen atom of the CNpy pyridine ring is the functional terminal group. Also, the SERS results point for a trans conformation for the trans- [Ru(CNpy)(NH3)4(pyS)]2+ complex and for a gauche configuration for the trans- [Ru(CNpy)(NH3)4(1,4-dt)]2+ and trans-[Ru(CNpy)(NH3)4(Tio)]2+ complexes on gold. The intensity dependence of some signals in the SERS spectra with the applie potential reflects the π back-bonding effect on surface since this behavior is observed to be strongly related to the E1/2 values of the complexes. The reductive desorption potentials of the SAMs formed with the isolated compounds reflects the π withdraw capability of the CNpy ligand. This effect is much more intense for the trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+ complex since the π back-bonding interaction of the 1,4-dt ligand is lower than the CNpy, pyS and Tio ligands. The heterogeneous electron transfer reaction of the cytochrome c metalloprotein was satisfactorily assessed with the SAMs formed by the isolated complexes (E1/2 = 0.05 V vs Ag⏐AgCl⏐Cl-). The Best voltammetric response was observed with the SAM of the trans- [Ru(CNpy)(NH3)4(pyS)]2+ complex due to the trans conformation on surface.
Os complexos trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+ (CNpy = 4-Cianopiridina, 1,4- dt = 1,4-ditiano), trans-[Ru(CNpy)(NH3)4(pyS)]2+ (pyS = 4-mercaptopiridina) e trans- [Ru(CNpy)(NH3)4(Tio)]2+ (Tio = tionicotinamida) foram sintetizados e caracterizados por Cromatografia Líquida de Alta Eficiência, análise elementar, eletroquímica e espectroscopias eletrônica e vibracional. Os espectros de absorção eletrônica e os resultados de eletroquímica evidenciaram uma interação do tipo π back-bonding do centro metálico RuII para os ligantes piridínicos. Os valores dos potenciais formais de meia onda (E1/2) observados para os complexos trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+, trans-[Ru(CNpy)(NH3)4(pyS)]2+ e trans-[Ru(CNpy)(NH3)4(Tio)]2+: 1,00, 0,67 e 1,03 V vs ENH, respectivamente, indicam a estabilização do estado reduzido do centro metálico em relação ao complexo de partida trans-[Ru(CNpy)(NH3)4(OH2)]2+ (E1/2 = 0,35 V vs ENH). Esse resultado indica, também, a forte capacidade π retiradora do ligante CNpy que, no caso do complexo trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+, é tão intensa que facilita comparativamente o processo de oxidação do centro metálico. Podese concluir, portanto, que a capacidade π retiradora dos ligantes CNpy, pyS e Tio é similar. O deslocamento na freqüência de estiramento da ligação C≡N do ligante Cnpy livre de 2239 para ∼2200 cm-1 após coordenação ao centro metálico [Ru(NH3)4]2+ nos espectros vibracionais indica que a coordenação do ligante CNpy ocorre pelo grupamento nitrila. Para os ligantes pyS e Tio, a observação das bandas atribuídas aos νC=S e νSH, respectivamente, indica que a coordenação ocorre pelo átomo de nitrogênio do anel piridínico. Os espectros SERS ex situ das superfícies modificadas com os compostos isolados permitem a classificação destes como moléculas modificadoras bifuncionais, onde o átomo de enxofre dos ligantes pyS, 1,4-dt e Tio atuam como sítio de adsorção e o átomo de nitrogênio piridínico do ligante CNpy atua como grupo funcional terminal. Além disso, os resultados SERS sugerem uma conformação trans para o complexo trans-[Ru(CNpy)(NH3)4(pyS)]2+ e gauche para os complexos trans-[Ru(CNpy)(NH3)4(1,4-dt)]2+ e trans-[Ru(CNpy)(NH3)4(Tio)]2+ sobre ouro. A dependência nas intensidades das bandas com o potencial aplicado aos eletrodos modificados ilustra o efeito π back-bonding dos íons metálicos dos adsorbatos inorgânicos, uma vez que observa-se uma relação direta com os valores dos potenciais formais de meia onda dos complexos estudados. Os valores dos potenciais de dessorção redutiva observados para as SAMs dos complexos isolados refletem a capacidade π retiradora do ligante CNpy que se encontra na posição para em relação ao sítio de adsorção. Esse efeito é bem mais intenso no complexo trans- [Ru(CNpy)(NH3)4(1,4-dt)]2+, uma vez que a capacidade de interação π back-bonding do ligante 1,4-dt é significativamente menor que as dos ligantes pyS e Tio. Sugere-se, para esse complexo, uma oxidação parcial do centro metálico o que implica em uma intensificação da interação σ com o ligante 1,4-dt (RuII-S) e, conseqüentemente, um enfraquecimento da ligação Au-S. A reação hTE da metaloproteína cyt c foi observada em valor consistente com seu estado in natura indicando que as SAMs estudadas acessam satisfatoriamente o processo hTE do cyt c além de evitar a desnaturação desta proteína. A forma das curvas voltamétricas, entretanto, apresentou uma dependência com a configuração dos complexos sobre a superfície. Curvas de melhor definição foram obtidas com a SAM do complexo trans-[Ru(CNpy)(NH3)4(pyS)]2+ que apresenta uma configuração trans em relação à superfície.
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Ben, Youssef Mariem. "Fonctionnalisation de surface des oxydes métalliques par des SAMs dipolaires; application aux cellules photovoltaïques." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC157/document.
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L'insertion de couches minces d'oxyde métallique (MO) à l'interface entre les électrodes conductrices (FTO / ITO, Métaux) et la couche active (polymère, pérovskite) constitue une solution prometteuse pour améliorer les performances des dispositifs photovoltaïques organiques et hybrides. La procédure consiste à introduire des couches MO fonctionnalisées par des monocouches auto-assemblées dipolaires (SAMs) à l'interface entre l'électrode conductrice et la couche active. Les couches SAMs supportant des dipôles perpendiculaires à la surface peuvent avoir un impact important sur les dispositifs électroniques à la fois en affectant la croissance et l'organisation de la couche organique active et en accordant le travail de sortie des couches MO. Dans ce travail, nous montrons que le greffage des molécules dipolaires sur des couches minces de MO peut affecter considérablement les performances des cellules photovoltaïques. Cet impact dépend fortement de l'orientation du dipôle permanent situé sur la molécule SAMThe insertion of very thin metal-oxide (MO) layers at the interface between the conductive electrodes (FTO/ITO, Metals) and the active layer (polymer, perovskite) presents a promising solution to improve the performances of organic and hybrid photovoltaic devices. The procedure is about introducing MO layers functionalized by dipolar self-assembling monolayer’s (SAMs) at the interface between the conductive electrode and the active layer. The SAM layers bearing dipoles perpendicular to the surface that can have a large impact on the electronic devices both by affecting the growth and organization of active organic layer and by tuning the work function of the MO layers. In this work we show that the grafting of dipole molecular on top of MO thin films can considerably affect the performance of the photovoltaic cell. The impact on these performances depends strongly on the orientation of the permanent dipole lying on the SAM molecule
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Bennett, Megan. "Energy Transfer Dynamics in Collisions of Polar and Non-polar Gases with Functionalized Self-Assembled Monolayers." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33229.
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Molecular beam scattering experiments are used to investigate the extent of thermal accommodation of Ne, CD4, ND3, and D2O in collisions with long chain CH3, NH2, and OH terminated self-assembled monolayers (SAMs) on gold. Surface rigidity, internal degrees of freedom of the impinging gas, and potential energy surface well depths have been explored as a way to predict the outcome of a gas-surface collision. Ne is used to assess the mechanical rigidity of the SAMs. The order of rigidity is CH3 < NH2 ~ OH. The NH2 and OH terminated SAMs are more rigid due to the intermolecular hydrogen bonding structure at the gas-surface interface. Despite the hydrogen bonding nature of the NH2 and OH terminated SAMs CD4, ND3, and D2O are extensively thermally accommodated on the surfaces, therefore surface rigidity is no solely responsible for energy transfer dynamics. It was found that the number of degrees of freedom do not predict how extensively a gas will thermally accommodate on a surface capable of hydrogen bonding. A qualitative correlation between increasing potential energy well depths and the extent of thermal accommodation has been established as a result of these scattering experiments.Master of Science
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Shuler, Shelby. "Investigation of Gas-Surface Dynamics Using an Ar Atomic Beam and Functionalized Self-Assembled Monolayers." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32686.
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Interactions of gas-phase molecules with surfaces are important in many ordinary
events, such as ozone depletion, corrison of metals, and heterogeneous catalysis. These
processes are controlled by the bonding, diffusion, and reactivity of the impinging gas
species. Our research employs molecular beam techniques and well-characterized
surfaces to study these processes.
The goal of this study is to better understand how the physical and chemical
nature of the surface interface influences energy transfer dynamics in gas-surface
collisions. An atomic beam is used to probe the energy transfer dynamics in collisions of
Argon with model surfaces of functionalized self-assembled monolayers (SAMs)
(1-dodecanethiol and 11-mercapto-1-undecanol) on gold. The beam is directed towards the surface
at an incident angle of 30 degrees and the scattered Ar atoms are detected at the specular angle
of 30 degrees. Time-of-flight scans measure the velocity distributions of atoms leaving the surface,
which correlate with the energy transfer dynamics of the impinging gas atoms.
Gas-surface energy transfer experiments are accomplished by directing an 80 kJ/mol
Ar atomic beam at a clean Au(111) surface and surfaces composed of hydroxyl-terminated
or methyl-terminated SAMs on Au(111). The fractional energy transferred to
the bare gold surface is 69 %, while it is grater than 77 % for the monolayer-covered
surfaces. The extent of thermalization on the surface during the collision is significantly
greater for the methyl-terminated surface than for the hydroxyl-terminated surface. Since the two
monolayers are similar in structure, packing density, and mass, the differences in
scattering dynamics are likely due to a combination of factors that may include
differences in the available energy modes between the two terminal groups and the
hydrogen-bonding nature of the hydroxyl-terminated SAM.Master of Science
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Meillan, Matthieu. "Immobilisation de biomolécules sur des monocouches auto-assemblées et élaboration de sondes AFM à nanotubes de carbonne fonctionnalisés pour des mesures d'interactions ligrand-récepteur." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0109/document.
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Lors de la mise au point de biocapteurs, le contrôle de l'état de surface sur laquelle sontimmobilisées les biomolécules est un paramètre crucial pour la fiabilité et la reproductibilité desmesures. Pour ce travail de Thèse, deux objectifs principaux ont été fixés :- obtenir de façon reproductible des films organiques fonctionnels capables de rendre lessurfaces inorganiques biocompatibles afin d'immobiliser des biomolécules sans les dénaturer.- se doter d'outils innovants afin d'analyser la distribution de biomolécules sur la surface etd'évaluer leur activité biologique à l'échelle de la molécule unique.L'immobilisation a été réalisée sur des SAMs terminées par une fonction acide carboxylique.Pour imager les surfaces nous avons choisi la Microscopie Atomique de Force (AFM) qui permetd'obtenir des informations à l'échelle nanométrique et de mesurer des interactions moléculaires del'ordre du piconewton (10-12 N).Des CNTs, générés par dépôt chimique en phase vapeur, sont fixés sur une pointe AFM. Puis Ilssont biofonctionnalisés selon un protocole de trempage original afin d'obtenir une modificationchimique sélective de leur apex. Les interactions entre un récepteur, immobilisé sur la surface, et sonligand, lié de façon covalente au CNT, sont mesurées à l'échelle de la molécule uniqueDuring the development of biosensors, control of the surface on which the biomolecules areimmobilized is a crucial parameter for the reliability and reproducibility of the measurements. For thisPhD work, two main objectives were set:- obtain in a reproducible way functional organic films able to make inorganic surfacebiocompatible for the immobilization of biomolecules without any denaturation.- develop innovative tools in order to analyze the distribution of biomolecules on the surface etevaluate their biological activity at single molecule scaleThe immobilization step was done on SAMs terminated by a carboxylic acid function.In order to image surfaces, Atomic Force Microscopy (AFM) was chosen. This technique permits toobtain information at nanometric scale and to measure molecular interactions in the range ofpiconewton forces (10-12 N).MWCNTs were linked to a commercial AFM tip by micro-welding under optical microscopy. CNTswere biofunctionalized at the nanotube apex by an original dipping procedure.The interactions between a ligand, immobilized on the surface, and a receptor covalently linked to aCNT have been characterized
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Bauer, Stella Valery [Verfasser], and Axel [Akademischer Betreuer] Rosenhahn. "Hydratation und Antifouling-Oberflächen: Modellsysteme auf Basis zwitterionischer SAMs und Polysaccharide / Stella Valery Bauer ; Betreuer: Axel Rosenhahn." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180301420/34.
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Jademan, Jessica, and Veronica Johansson. "”Vi sa bara förlåt och sedan blev vi sams" : En studie om konflikter och bemötande i förskolan." Thesis, Högskolan i Borås, Akademin för bibliotek, information, pedagogik och IT, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-10314.
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BakgrundI detta arbete studerar vi barns bemötande utifrån olika konfliktsituationer som kan uppstå utifrån ett barns perspektiv. Med vårt arbete vill vi belysa vikten med aktivt arbete för konflikthantering.SyfteSyftet med vår uppsats är att studera barns perspektiv på konflikter som uppstår i förskolan samt hur bemötandet barn emellan ser ut under konfliktsituationen.MetodVårt metodval består av en kvalitativ samt kvantitativ undersökning där vi valde att använda oss av intervjuer med barn och även schematiska observationsscheman. Syftet med dessa metodval är att vi skulle kunna bilda oss en uppfattning ur ett barns perspektiv.ResultatResultatet visar att konflikter är en del av förskolans vardag framför allt i förskolans innemiljö. Barnen har i det stora hela en gemensam syn att en konflikt innebär en fysisk handling. Utefter vårt resultat kan vi också konstatera hur viktigt det är att barn inom förskolans verksamhet får kunskap och möjligheter till att sätta ord på sina känslor samt kunskap om olika alternativ till att hantera en konflikt. För att ge barnen dessa förutsättningar krävs det att pedagogerna har kunskap om hur de kan arbeta dagligen men även på ett förebyggande sätt kring konflikter samt konflikthantering.
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Mearns, Freya Justine Chemistry Faculty of Science UNSW. "A study of hybridisation of DNA immobilised on gold: strategies for DNA biosensing." Awarded by:University of New South Wales. Chemistry, 2006. http://handle.unsw.edu.au/1959.4/23978.
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This thesis outlines a study of the physical changes that hybridisation imposes on single-stranded DNA (ssDNA) immobilised by one end to a substrate, and of how such physical changes can be exploited to detect specific sequences of DNA in a target solution. The system studied was composed of a mixed monolayer of 20mer ssDNA with C6 alkanethiolate modifications on their 3??? ends and short-chain hydroxyterminated alkanethiolates, on a gold substrate. It was prepared using the self-assembly properties of alkanethiols on gold. Atomic force microscopy images showed that the end-immobilised ssDNA is flexible enough to lie over the diluent hydroxy-terminated self-assembled monolayer (SAM). Hybridisation was shown to cause the DNA to become more rigid and stand up off the substrate due to an increase in persistence length. Such physical changes of the DNA upon hybridisation were significant enough to be exploited in the development of a DNA recognition interface. The recognition interface was designed with the view of keeping it both simple to make and simple to use, and was coupled with electrochemical transduction. A label-free recognition interface was developed that relied on the oxidation of the sulfur head group of the alkanethiolate SAM to detect hybridisation (firstly air oxidation and then electrochemical oxidation). It produced a positive signal upon hybridisation with complementary target DNA. Improvements in the reliability and robustness of the recognition interface were made using a labelled approach. The labelled version employed electroactive molecules as labels on the 5??? ends of the probe DNA strands. Two labels were investigated ??? anthraquinone and ferrocene. The flexibility of the ssDNA ensured that the redox labels were able to directly access the underlying gold electrode. Hybridisation was expected to remove the labels from the electrode due to an increase in the DNA???s persistence length, and thus perturb the electrochemical signal. The use of ferrocene as a label provided a ???proof-of-concept??? for the system. The labelled recognition interface provides a foundation for the future development of a simple, reliable, and selective DNA hybridisation biosensor.
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von, Sydow Rebecca. "Social blandning och blandade upplåtelseformer : En kvantitativ studie med tonvikt på nyproducerade bostadsområden." Thesis, Stockholms universitet, Kulturgeografiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-90498.
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Bostadsfrågor utgör en stor del i samhällsplanering, och boendesegregation har under de senaste åren uppmärksammats. Syftet med denna masteruppsats är att analysera befolkningssammansättningen i nyproducerade bostadsområden med särskilt fokus på blandade upplåtelseformer som metod för att uppnå social blandning. Uppsatsen är skriven på uppdrag av Arbetsmarknadsdepartementet och grundas i en teori om att blandade upplåtelseformer bidrar till en ökad social blandning och därmed ett mindre boendesegregerat samhälle. Teorier angående social blandning och dess effekter, samt strategin att blanda upplåtelseformer diskuteras. Frågeställningarna lyder: Bidrar social blandning i nyproducerade bostadsområden till mindre boendesegregation? Hur ser en eventuell förändring av befolkningssammansättningen ut i upplåtelseformerna? Har upplåtelseformer i nyproduktion förändrats över tid? Vilken roll har hyresrätten? Metoden är kvantitativ och bygger på LOUISE-data inom projektet SPaDE, och behandlar SAMS-områden i utvalda kommuner och stadsdelar i Sverige. Resultatet visar bland annat en skillnad mellan befolkningen i befintliga bostadsområden med befolkningen i områden med nyproduktion, trots en ökad blandning av upplåtelseformer och en ökad andel hyresrätter. Befolkningsutvecklingen ser även olika ut över tid då färre är arbetslösa, har socialbidrag eller studiebidrag, och fler är födda i Sverige, inom områden med nyproduktion. Den sociala blandningen som eftersträvas kan kopplas till blandade upplåtelseformer, men detta sker på olika skalor och kontext och förutsättningar är avgörande.SPaDE
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Mehring, Patrick Dennis [Verfasser], Carsten [Akademischer Betreuer] Westphal, and Thomas [Gutachter] Weis. "SAMs organischer Halbleiter auf Au-Substraten : Eine STM-Untersuchung / Patrick Dennis Mehring. Betreuer: Carsten Westphal. Gutachter: Thomas Weis." Dortmund : Universitätsbibliothek Dortmund, 2013. http://d-nb.info/1103591363/34.
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Mehring, Patrick [Verfasser], Carsten [Akademischer Betreuer] Westphal, and Thomas [Gutachter] Weis. "SAMs organischer Halbleiter auf Au-Substraten : Eine STM-Untersuchung / Patrick Dennis Mehring. Betreuer: Carsten Westphal. Gutachter: Thomas Weis." Dortmund : Universitätsbibliothek Dortmund, 2013. http://d-nb.info/1103591363/34.
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Paulo, TÃrcio de Freitas. "SAMs de MolÃculas Sulfuradas: Estudo TermodinÃmico e CinÃtico de AdsorÃÃo e AplicaÃÃo em ReaÃÃes de TransferÃncia de ElÃtrons de Metaloproteinas." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6337.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorO emprego das tÃcnicas de eletroquÃmica, microbalanÃa de cristal quartzo (QCM â Quartz Crystal Microbalance) e ressonÃncia de plÃsmons de superfÃcie (SPR â Surface Plasmon Resonance) mostram que as espÃcies 1,4-ditiano (1,4-dt), 4-mercaptopiridina (pyS), 5-(4-piridil)-1,3,4-oxadiazol-2-tiol (Hpyt), tionicotinamida (TNA) e isotionicotinamida (iTNA) experimentam adsorÃÃo espontÃnea formando SAMs (Self-Assembled Monolayers) como resultado da imersÃo de substratos de ouro em soluÃÃo contendo estas espÃcies. As imagens obtidas por microscopia de varredura por tunelamento (STM â Scanning Tunneling Microscopy) indicam um arranjo prÃximo do hexagonal com exceÃÃo da iTNA cujas imagens nÃo foram conclusivas. Adicionalmente, as imagens indicam a existÃncia de defeitos nas SAMs mesmo apÃs longos perÃodos de imersÃo (24 h). Os estudos termodinÃmicos e cinÃticos dos processos de adsorÃÃo foram realizados por desorÃÃo redutiva em meio alcalino e QCM. Os valores dos potenciais de desorÃÃo redutiva, Edr, foram observados em −0,9, −0,8 e −0,5 V vs. Ag/AgCl/Cl- para a desorÃÃo de iTNA, TNA e Hpyt, respectivamente. Comparativamente Ãs espÃcies 1,4-dt (−0,8 V) e pyS (−0,5 V), o valor de Edr da SAM de Hpyt indica uma interaÃÃo sigma ao passo que aqueles observados para iTNA e TNA sugerem uma contribuiÃÃo pi adicional. Os valores de quantidade de material adsorvido (gama) e da taxa de recobrimento da superfÃcie (teta), calculados por desorÃÃo redutiva e impedÃncia eletroquÃmica, respectivamente, foram consistentes com as imagens de STM. Comparativamente aos resultados de desorÃÃo, os maiores valores de gama determinados por QCM foram atribuÃdos à presenÃa de molÃculas de Ãgua co-adsorvidas visto que foi observada uma relaÃÃo linear entre o excesso de massa e o momento de dipolo das espÃcies modificadoras. As curvas de desorÃÃo obtidas para pyS indicam a decomposiÃÃo da monocamada nÃo possibilitando, portanto, a determinaÃÃo dos parÃmetros termodinÃmicos e cinÃticos de adsorÃÃo. A correlaÃÃo com os resultados obtidos apÃs imersÃo do eletrodo de ouro em soluÃÃo de Na2S sugere que este processo està associado à quebra da ligaÃÃo C─S com formaÃÃo de uma camada de enxofre atÃmico e/ou oligomÃrico. As isotermas de adsorÃÃo obtidas para os processos de formaÃÃo das SAMs de Hpyt, TNA e iTNA, adequaram-se ao modelo de Langmuir permitindo a determinaÃÃo da variaÃÃo da energia livre de adsorÃÃo, ΔGads, como −35,9, −38,5 e −34,9 kJ mol−1, respectivamente. Estes valores sÃo indicativos de interaÃÃo forte sendo caracterÃsticos de processos de quimissorÃÃo. Para o modelo de Frumkin, os dados apresentaram melhores correlaÃÃes quando o parÃmetro de interaÃÃo (g) foi fixado em −0,45, −0,30 e −0,10, respectivamente, para as SAMs de Hpyt, TNA e iTNA indicando interaÃÃes repulsivas entre as molÃculas adjacentes. Os valores de pKa das SAMs de Hpyt (4,2), TNA (5,0 e 8,5) e iTNA (4,5 e 7,9) foi determinado por voltametria utilizando-se o Ãon complexo [Fe(CN)6]3−. Neste estudo, foram sugeridas modificaÃÃes, uma vez que o mÃtodo proposto na literatura dificulta a determinaÃÃo de mais de um valor de pKa como observado para as molÃculas de TNA e iTNA. As reaÃÃes de transferÃncia de elÃtrons (TE) das metaloproteÃnas citocromo c (cyt c) e mioglobina (Mb) foram estudadas utilizando-se as SAMs de Hpyt, TNA, iTNA, pyS e 1,4-dt. Para as SAMs de TNA e iTNA, o deslocamento positivo de 0,2V no valor do potencial de meia-onda do cyt c (pH~7,0) em relaÃÃo a forma nativa, foi atribuÃdo à densidade de carga positiva resultante da protonaÃÃo do grupo NH2 (pKa ~ 8,0). Resultados de QCM e SPR indicaram que hà a formaÃÃo de uma monocamada de cyt c sobre as SAMs estudadas. Esta monocamada, embora nÃo sendo redox ativa, permite o estudo da reaÃÃo de TE das molÃculas de cyt c em soluÃÃo sugerindo que este processo pode envolver os orbitais das molÃculas modificadoras. Para a metaloproteÃna Mb, utilizou-se uma SAM formada pelo aminoÃcido L-cisteÃna (cys), uma vez que nenhuma das SAMs estudadas acessou a reaÃÃo de TE. O processo redox foi observado em 0,086 V o que sugere a forma nativa. Os dados de QCM e SPR indicaram, tambÃm, a formaÃÃo de uma monocamada sobre a SAM de cys (Au/cys/Mb). Valores de â49,67 kJ mol−1 e −0,15 para ΔGads e g, respectivamente, foram calculados para a formaÃÃo da monocamada de Mb sobre a SAM de cys. O eletrodo Au/cys/Mb apresentou atividade catalÃtica em relaÃÃo a reaÃÃo de oxidaÃÃo do Ãcido ascÃrbico com uma diminuiÃÃo de 400 mV no sobrepotencial e uma reaÃÃo cineticamente controlada com uma constante de velocidade, kf, de ~2,0 x 10^4 L mol-1 s-1.
Electrochemical techniques, quartz crystal microbalance (QCM) and surface plÃsmons resonance (SPR) were used to study the formation of self-assembled monolayers (SAMs) of 1,4-ditiano (1,4-dt), 4-mercaptopyridine (pyS), 5-(4-piridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt), thionicotinamide (TNA) and thioisonicotinamide (iTNA) as a result of the immersion of gold substrates into the respective solutions. STM (Scanning Tunneling Microscopy) images indicate the sulfur atom as the adsorption site of these molecules and a hexagonal conformation on surface. For the iTNA molecule, the images were not conclusive. In addition, the images indicated the existence of defects even after longer immersion times (24 h). Thermodynamic and kinetic aspects of the adsorption process were evaluated by reductive desorption in alkaline media and QCM. The reductive desorption potentials, Edr, were observed at −0.9, −0.8, and −0.5 V vs. Ag/AgCl for the desorption of iTNA, TNA and Hpyt, respectively. In comparison to 1,4-dt (−0.8 V) and pyS (−0.5 V) species, the Edr value of Hpyt indicates a sigma interaction whereas those of iTNA and TNA indicate an additional pi contribution. The values of the concentration of adsorbed material, gama, and fractional coverage (teta ~ 0.9), determined, respectively, by reductive desorption and impedance are consistent with the STM images. In comparison to the desorption data, the higher values of gama calculated by QCM were assigned to the presence of water molecules since a linear relation was observed between the dipole moment and the mass change calculated by QCM. The desorption curves acquired for the pyS SAM indicated the decomposition of the monolayer thus not allowing the determination of the thermodynamic and kinetic parameters of adsorption. In comparison with the results obtained for the electrode modified after immersion in Na2S solution, it was suggested that this process is associated to the cleavage of the C─S bond which results in the formation of an adlayer composed of atomic and/or oligomeric sulfur species. The adsorption isotherms for Hpyt, TNA and iTNA fitted the Langmuir model of adsorption allowing the determination of the free energy of adsorption, ΔGads, as −35.9, −38.5 and −34,9 kJ/mol, respectively. These values are indicative of strong interaction being typical of chemisorption. For the Frumkin model, the best correlation was found when the interaction parameter, g, was established as −0.45, −0.20 and −0.10 for Hpyt, TNA and iTNA, respectively, indicating repulsive interactions between the adjacent molecules. Cyclic voltammetry was used to determinate the pKa of the SAMs of Hpyt (4.2), TNA (5.0 and 8.5) and iTNA (4.5 and 7.9) by using [Fe(CN)6]3− as a probe molecule. For this study, some changes were suggested since in the method proposed in the literature the existence of more than one protonation site was not considered thus not allowing the determination of more than one pKa value as was observed for TNA and iTNA molecules. Electron transfer reactions (TE) of cytochrome c (cyt c) and myoglobin (Mb) metalloproteins were studied by using the SAMs of Hpyt, TNA, iTNA, pyS and 1,4-dt. For the SAMs formed with TNA and iTNA, the positive shift of 0.2V on the half-wave potential of cyt c in relation to that of the native protein, was assigned to the positive charge density on surface in consequence of the protonation of NH2 groups (pKa~8.0) since these measurements were carried out in physiological medium. QCM and SPR data indicated the formation of a monolayer of cyt c on the studied SAMs. This monolayer, although not being electroactive, allows the study of the TE reaction of the cyt c molecules in solution suggesting that this process involves the orbitals of the modifier molecules. For the Mb metalloprotein, a SAM of L-cysteine amino acid was used since none of the studied sulfur molecules was able to access the TE reaction. The redox process was observed at 0.086 V suggesting the native form of Mb. QCM and SPR data indicated, also, the formation of a monolayer of Mb on the cys SAM (Au/cys/Mb). Values of â49.67 kJ mol−1 and −0.15 for ΔGads and g, respectively, were calculated for the formation of the monolayer of Mb on the cys SAM. The electrode Au/cys/Mb presented catalytic activity toward the oxidation reaction of ascorbic acid presenting a decrease of 400 mV in the overpotential and a kinetic controlled with a rate constant, kf, of 2.0 x 104 L mol-1 s-1.
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Cavadas, Francisco Troitino. "Spectroscopic and electrochemical investigation of phenyl, phenoxy, and hydroxyphenyl-terminated alkanethiol monolayers." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/28611.
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4-(12-mercaptododecyloxy)phenol (1), 3-(12-mercaptododecyloxy)phenol (2), 4-(12-mercaptododecyl)phenol (3), 4-(12-mercapto-dodecyl)phenol (4), 12-phenyldodecyl-mercaptan (5), 12-phenylundecyoxymercaptan (6), 4-(6-mercapto-hexyl)phenol (7), and 4-(12-mercaptododecyloxy)phenol (8) were synthesized. The thiol products were characterized by NMR, HRMS, and elemental analysis. Self-assembled monolayers (SAMs) on gold substrates were prepared from thiols 1-8, and the resulting monolayer surfaces were analyzed using Reflectance Absorbance Infrared Spectroscopy (RAIRS), contact angle goniometry, ellipsometry, reductive desorption cyclic voltametry, and impedance spectroscopy.
Several aromatic C-C vibrational frequencies in the RAIRS spectra, for SAMs of 1-8, reveal a dependence of peak intensity on substitution regiochemistry of the aromatic ring. This result suggests that the orientation of the aromatic ring changes with substitution. Peak intensity, and peak widths of alkyl C-H vibrational features in the RAIRS spectra also reveal a dependence of the environment of the alkyl chain on structure of thiols 1-8. Meta-substitution seems to significantly alter the projection of the terminal -OH group relative to para-substitution.
Contact angles were obtained for each SAM surface using water, glycerol, and ethylene glycol. From the contact angle data, Zisman and Fowkes analyses were performed in order to determine surface free energy values and also to determine the dispersive contribution to the surface energy. The energy values obtained from the Zisman plots as well as the dispersive contributions obtained from the Fowkes plots suggest a dependence of surface energy on substitution regiochemistry of the aromatic ring. The results are consistent with the interpretation of the RAIRS spectra as they relate to the effect substitution regiochemistry has on SAM structure and interfacial properties.
The results of the reductive desorption measurements performed on each monolayer surface, indicate that changes in substitution regiochemistry do not seem to affect the surface coverage of SAMs 1-8. Desorption potentials however, are affected by the structure of the thiols composing the SAM, which suggests that the lateral stability resulting from interactions of the terminal groups and alkyl chains, is different for each monolayer surface. Specifically SAMs of 12-phenyldodecylmercaptan (5) and SAMs of 4-(12-mercaptododecyloxy)phenol (1) seem to be more stable due to interactions of the terminal aromatic ring in SAMs of (5) and due to an increase in van der Waals interactions in SAMs of (1).
Film thicknesses, as determined by ellipsometry, also suggest that meta-substitution of the aromatic ring results in lower thicknesses for SAMs of (4), which is consistent with the interpretation of the structural changes resulting from meta-substitution, suggested by the interpretation of the RAIRS spectrum of SAMs of (4). Thickness measurements also indicate that most of the functionalized SAMs (1-4, 7, 8) react with OTS, which suggests the terminal -OH group is not shielded at the interface and is available for reaction. Following reaction with OTS the RAIRS spectra of the reacted surfaces reveal structural changes to the underlying SAM.
Impedance spectroscopic measurements performed on SAMs of 1-8 reveal what seems to be a correlation between the orientation of the aromatic ring and the resistance properties of the SAM. It appears meta-substitution of the ring lowers the monolayers ability to resist electron transfer.
These data suggest that meta-substitution of the aromatic ring has a significant impact upon the structure of the resulting monolayer relative to monolayers composed of para-substituted molecules. The data also suggests that there is a correlation between molecular structure and interfacial properties particularly as it relates to surface energy and reactivity. Small atomic changes in the molecules composing the SAM result in measurable differences in macroscopic properties of the interface. It is important to recognize the need for understanding structure-property relationships in self-assembled monolayers particularly if logical design of surfaces is to be achieved and applied towards solving problems associated with corrosion and adhesion of metal surfaces.Ph. D.
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Jakubowicz, Agnieszka. "Investigation of growth kinetics of self-assembling monolayers by means of contact angle, optical ellipsometry, angle-resolved XPS and IR spectroscopy." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4602/.
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Absorption of octadecanethiol and p-nitrobenzenethiol onto gold surfaces from ethanol solutions has been studied by means of contact angle, optical ellipsometry, angle-resolved XPS (ARXPS), and with grazing angle total reflection FTIR. Growth of the monolayers from dilute solutions has been monitored and Langmuir isotherm adsorption curves were fitted to experimental data. A saturated film is formed within approximately 5h after immersion in solutions of concentrations ranging from 0.0005mM to 0.01mM. We found, that the final density of monolayer depends on the concentration of the solution.
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Böhmler, Judith. "Well-controlled and well-described SAMs-based platforms for the study of material-bacteria interactions occuring at the molecular scale." Phd thesis, Université de Haute Alsace - Mulhouse, 2012. http://tel.archives-ouvertes.fr/tel-00847480.
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Bacterial adhesion is the first step of biofilm formation and in the focus of research interest since several decades. Biofilms cause many problems, sometimes dramatic, for example in health, food packing or waste water purification. Despite of high interest, bacterial adhesion process is only poorly understood yet. In this work, bacterial adhesion was investigated on well-organized and structured model surfaces with various chemistries at molecular scale. For that purpose a characterization methodology was developed to sufficiently analyze monolayers on silicon wafers, and controlled mixed monolayers surfaces with different densities of NH 2 backfilled with CH3 were developed and optimized. These controlled surfaces with different densities of 0 % NH2 up to 100% NH2 were eventually used as tool to study bacterial adhesion in batch and real time conditions. The results demonstrate a significant impact on bacterial adhesion of weak difference in the surface chemistry at molecular scale. In the batch experiments, two so-called "plateaus" zones were determined, in which bacterial adhesion is not significantly different despite the change of the amine concentration on the surface. On the contrary, one transition zone exists between the "plateaus" in which a slight chunge.in the amine concentration leads to a significant increase / decrease of the bacterial adhesion. The same trend of bacteria behavior was observed for different bacterial strains.
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Fast, Ellen [Verfasser], Thisbe K. [Akademischer Betreuer] Lindhorst, and Ulrich [Gutachter] Lüning. "Synthese von Glycoazobenzol-Konjugaten zur Verbesserung der Photoschaltbarkeit von Glyco-SAMs / Ellen Fast ; Gutachter: Ulrich Lüning ; Betreuer: Thisbe K. Lindhorst." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1203624603/34.
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Paulo, Tércio de Freitas. "SAMs de Moléculas Sulfuradas: Estudo Termodinâmico e Cinético de Adsorção e Aplicação em Reações de Transferência de Elétrons de Metaloproteinas." reponame:Repositório Institucional da UFC, 2011. http://www.repositorio.ufc.br/handle/riufc/10364.
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PAULO, T. F. SAMs de Moléculas Sulfuradas: Estudo Termodinâmico e Cinético de Adsorção e Aplicação em Reações de Transferência de Elétrons de Metaloproteinas. 2011. 145 f. Tese (Doutorado em Química) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2011.Submitted by Daniel Eduardo Alencar da Silva (dealencar.silva@gmail.com) on 2014-11-28T20:27:24Z No. of bitstreams: 1 2011_tese_tfpaulo.pdf: 4290650 bytes, checksum: 1da8fc74403953d546dbf330e21660e2 (MD5)
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Electrochemical techniques, quartz crystal microbalance (QCM) and surface plásmons resonance (SPR) were used to study the formation of self-assembled monolayers (SAMs) of 1,4-ditiano (1,4-dt), 4-mercaptopyridine (pyS), 5-(4-piridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt), thionicotinamide (TNA) and thioisonicotinamide (iTNA) as a result of the immersion of gold substrates into the respective solutions. STM (Scanning Tunneling Microscopy) images indicate the sulfur atom as the adsorption site of these molecules and a hexagonal conformation on surface. For the iTNA molecule, the images were not conclusive. In addition, the images indicated the existence of defects even after longer immersion times (24 h). Thermodynamic and kinetic aspects of the adsorption process were evaluated by reductive desorption in alkaline media and QCM. The reductive desorption potentials, Edr, were observed at −0.9, −0.8, and −0.5 V vs. Ag/AgCl for the desorption of iTNA, TNA and Hpyt, respectively. In comparison to 1,4-dt (−0.8 V) and pyS (−0.5 V) species, the Edr value of Hpyt indicates a sigma interaction whereas those of iTNA and TNA indicate an additional pi contribution. The values of the concentration of adsorbed material, gama, and fractional coverage (teta ~ 0.9), determined, respectively, by reductive desorption and impedance are consistent with the STM images. In comparison to the desorption data, the higher values of gama calculated by QCM were assigned to the presence of water molecules since a linear relation was observed between the dipole moment and the mass change calculated by QCM. The desorption curves acquired for the pyS SAM indicated the decomposition of the monolayer thus not allowing the determination of the thermodynamic and kinetic parameters of adsorption. In comparison with the results obtained for the electrode modified after immersion in Na2S solution, it was suggested that this process is associated to the cleavage of the C─S bond which results in the formation of an adlayer composed of atomic and/or oligomeric sulfur species. The adsorption isotherms for Hpyt, TNA and iTNA fitted the Langmuir model of adsorption allowing the determination of the free energy of adsorption, ΔGads, as −35.9, −38.5 and −34,9 kJ/mol, respectively. These values are indicative of strong interaction being typical of chemisorption. For the Frumkin model, the best correlation was found when the interaction parameter, g, was established as −0.45, −0.20 and −0.10 for Hpyt, TNA and iTNA, respectively, indicating repulsive interactions between the adjacent molecules. Cyclic voltammetry was used to determinate the pKa of the SAMs of Hpyt (4.2), TNA (5.0 and 8.5) and iTNA (4.5 and 7.9) by using [Fe(CN)6]3− as a probe molecule. For this study, some changes were suggested since in the method proposed in the literature the existence of more than one protonation site was not considered thus not allowing the determination of more than one pKa value as was observed for TNA and iTNA molecules. Electron transfer reactions (TE) of cytochrome c (cyt c) and myoglobin (Mb) metalloproteins were studied by using the SAMs of Hpyt, TNA, iTNA, pyS and 1,4-dt. For the SAMs formed with TNA and iTNA, the positive shift of 0.2V on the half-wave potential of cyt c in relation to that of the native protein, was assigned to the positive charge density on surface in consequence of the protonation of NH2 groups (pKa~8.0) since these measurements were carried out in physiological medium. QCM and SPR data indicated the formation of a monolayer of cyt c on the studied SAMs. This monolayer, although not being electroactive, allows the study of the TE reaction of the cyt c molecules in solution suggesting that this process involves the orbitals of the modifier molecules. For the Mb metalloprotein, a SAM of L-cysteine amino acid was used since none of the studied sulfur molecules was able to access the TE reaction. The redox process was observed at 0.086 V suggesting the native form of Mb. QCM and SPR data indicated, also, the formation of a monolayer of Mb on the cys SAM (Au/cys/Mb). Values of –49.67 kJ mol−1 and −0.15 for ΔGads and g, respectively, were calculated for the formation of the monolayer of Mb on the cys SAM. The electrode Au/cys/Mb presented catalytic activity toward the oxidation reaction of ascorbic acid presenting a decrease of 400 mV in the overpotential and a kinetic controlled with a rate constant, kf, of 2.0 x 104 L mol-1 s-1.
O emprego das técnicas de eletroquímica, microbalança de cristal quartzo (QCM – Quartz Crystal Microbalance) e ressonância de plásmons de superfície (SPR – Surface Plasmon Resonance) mostram que as espécies 1,4-ditiano (1,4-dt), 4-mercaptopiridina (pyS), 5-(4-piridil)-1,3,4-oxadiazol-2-tiol (Hpyt), tionicotinamida (TNA) e isotionicotinamida (iTNA) experimentam adsorção espontânea formando SAMs (Self-Assembled Monolayers) como resultado da imersão de substratos de ouro em solução contendo estas espécies. As imagens obtidas por microscopia de varredura por tunelamento (STM – Scanning Tunneling Microscopy) indicam um arranjo próximo do hexagonal com exceção da iTNA cujas imagens não foram conclusivas. Adicionalmente, as imagens indicam a existência de defeitos nas SAMs mesmo após longos períodos de imersão (24 h). Os estudos termodinâmicos e cinéticos dos processos de adsorção foram realizados por desorção redutiva em meio alcalino e QCM. Os valores dos potenciais de desorção redutiva, Edr, foram observados em −0,9, −0,8 e −0,5 V vs. Ag/AgCl/Cl- para a desorção de iTNA, TNA e Hpyt, respectivamente. Comparativamente às espécies 1,4-dt (−0,8 V) e pyS (−0,5 V), o valor de Edr da SAM de Hpyt indica uma interação sigma ao passo que aqueles observados para iTNA e TNA sugerem uma contribuição pi adicional. Os valores de quantidade de material adsorvido (gama) e da taxa de recobrimento da superfície (teta), calculados por desorção redutiva e impedância eletroquímica, respectivamente, foram consistentes com as imagens de STM. Comparativamente aos resultados de desorção, os maiores valores de gama determinados por QCM foram atribuídos à presença de moléculas de água co-adsorvidas visto que foi observada uma relação linear entre o excesso de massa e o momento de dipolo das espécies modificadoras. As curvas de desorção obtidas para pyS indicam a decomposição da monocamada não possibilitando, portanto, a determinação dos parâmetros termodinâmicos e cinéticos de adsorção. A correlação com os resultados obtidos após imersão do eletrodo de ouro em solução de Na2S sugere que este processo está associado à quebra da ligação C─S com formação de uma camada de enxofre atômico e/ou oligomérico. As isotermas de adsorção obtidas para os processos de formação das SAMs de Hpyt, TNA e iTNA, adequaram-se ao modelo de Langmuir permitindo a determinação da variação da energia livre de adsorção, ΔGads, como −35,9, −38,5 e −34,9 kJ mol−1, respectivamente. Estes valores são indicativos de interação forte sendo característicos de processos de quimissorção. Para o modelo de Frumkin, os dados apresentaram melhores correlações quando o parâmetro de interação (g) foi fixado em −0,45, −0,30 e −0,10, respectivamente, para as SAMs de Hpyt, TNA e iTNA indicando interações repulsivas entre as moléculas adjacentes. Os valores de pKa das SAMs de Hpyt (4,2), TNA (5,0 e 8,5) e iTNA (4,5 e 7,9) foi determinado por voltametria utilizando-se o íon complexo [Fe(CN)6]3−. Neste estudo, foram sugeridas modificações, uma vez que o método proposto na literatura dificulta a determinação de mais de um valor de pKa como observado para as moléculas de TNA e iTNA. As reações de transferência de elétrons (TE) das metaloproteínas citocromo c (cyt c) e mioglobina (Mb) foram estudadas utilizando-se as SAMs de Hpyt, TNA, iTNA, pyS e 1,4-dt. Para as SAMs de TNA e iTNA, o deslocamento positivo de 0,2V no valor do potencial de meia-onda do cyt c (pH~7,0) em relação a forma nativa, foi atribuído à densidade de carga positiva resultante da protonação do grupo NH2 (pKa ~ 8,0). Resultados de QCM e SPR indicaram que há a formação de uma monocamada de cyt c sobre as SAMs estudadas. Esta monocamada, embora não sendo redox ativa, permite o estudo da reação de TE das moléculas de cyt c em solução sugerindo que este processo pode envolver os orbitais das moléculas modificadoras. Para a metaloproteína Mb, utilizou-se uma SAM formada pelo aminoácido L-cisteína (cys), uma vez que nenhuma das SAMs estudadas acessou a reação de TE. O processo redox foi observado em 0,086 V o que sugere a forma nativa. Os dados de QCM e SPR indicaram, também, a formação de uma monocamada sobre a SAM de cys (Au/cys/Mb). Valores de –49,67 kJ mol−1 e −0,15 para ΔGads e g, respectivamente, foram calculados para a formação da monocamada de Mb sobre a SAM de cys. O eletrodo Au/cys/Mb apresentou atividade catalítica em relação a reação de oxidação do ácido ascórbico com uma diminuição de 400 mV no sobrepotencial e uma reação cineticamente controlada com uma constante de velocidade, kf, de ~2,0 x 10^4 L mol-1 s-1.
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Adamkiewicz, Malgorzata. "Self-assembled monolayers on silicon : deposition and surface chemistry." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3938.
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Fabrication of surfaces with versatile functional groups is an important research area. Hence, it is essential to control and tune the surface properties in a reliable manner. Vinyl-terminated self-assembled monolayers (SAMs) offer significant flexibility for further chemical modification and can serve as a versatile starting point for tailoring of surface properties. Here a synthetic route for the preparation of vinyl-terminated trichlorosilane self-assembling molecules: 9-decenyltrichlorosilane (CH₂=CH-(CH₂)₈-SiCl₃), 10-undecenyltrichlorosilane (CH₂=CH-(CH₂)₉-SiCl₃), and 14-pentadecenyltrichlorosilane (CH₂=CH-(CH₂)₁₃-SiCl₃) is presented. These molecules were used for the preparation of SAMs in either liquid or vapour phase processes. Commercially available methyl-terminated self-assembling molecules: decyltrichlorosilane (CH₃-(CH₂)₉-SiCl₃) and octadecanetrichlorosilane (CH₃-(CH₂)₁₇-SiCl₃) were used as controls. The resultant films were characterised by X-ray photoelectron spectroscopy (XPS), contact angle analysis, ellipsometry, and atomic force microscopy (AFM). Well defined, vinyl-terminated SAMs were further chemically modified with carbenes (:CCl₂, :CBr₂, :CF₂) and hexafluoroacetone azine (HFAA). The reactions were performed in the liquid or the vapour phase. The resulting SAMs were characterised using the same methods as for the vinyl-terminated monolayers. Successful modification was confirmed by the appearance of new signals in the XPS spectrum, with simultaneous changes in water contact angle values and unchanged thickness values. Methyl-terminated SAMs were also exposed to carbenes and HFAA as a control system. These are the first examples of C-C bond formation on SAMs in the vapour phase.
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Wiley, Devon S. "Oxide Nanofilms from Nanoparticle Suspensions Deposited on Functionalized Surfaces." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1217022473.
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Mousli, Yannick. "Synthès de nano-films bio-fonctionnels pour l'immobilisation spécifique d'espèces biologiques." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0840/document.
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Le contrôle des propriétés physicochimiques et de l’état de surface des solides constituent un enjeu majeur pour le développement des biotechnologies, et notamment des bio-capteurs. Pour des applications en analyse et diagnostic biologique, la fonctionnalisation des surfaces à base de silicium peut être réalisée grâce à la formation d’un nano-film organique appelé SAM (Self-Assembled Monolayer). L'objectif de ce travail de thèse est ainsi de synthétiser des monocouches sur des substrats de silice afin de les rendre biofonctionnels en vue de développer une plateforme de biodétection polyvalente.Pour ce faire, deux types d'agents de couplages ont été envisagés : l'un possédant un motif azoture et l'autre une biotine. L’obtention de ces deux types de molécules a fait l’objet d’un travail de synthèse permettant d’aboutir à de nouveaux organosilanes fonctionnels directement greffables sur des surfaces de SiO2. La biofonctionnalité est introduite sur le substrat par la biotine, soit directement lors de la formation de la SAM, soit par chimie click sur les monocouches fonctionnalisées par des azotures.Les différentes surfaces obtenues ont ensuite été caractérisées par Spectroscopie Infrarouge de Réflexion–Absorption par Modulation de Polarisation (PM-IRRAS) et par Microscopie de Force Atomique (AFM). La bioactivité des SAMs biotinylées a enfin été évaluée par un protocole mettant en jeu une streptavidine modifiée par une enzyme (la HRP) capable de catalyser des réactions d’oxydoréduction de molécules chromogènesControl of surface physicochemical properties is a key aspect for the development of many biotechnological tools, such as biosensors. For analysis and diagnostic, the functionalization of silica-based surfaces may be carried out through the creation of an organic nano-film named a Self-Assembled Monolayer (SAM). The main goal of this PhD work is thus to synthesize monolayer on SiO2 substrates in order give them biofunctionality, aiming at developing a versatile biodetection platform.In order to do so, we focused on the synthesis of two types of coupling agents, either bearing an azide moiety or a biotin. This organic synthesis work led to two new sorts of functional organosilanes which can be directly grafted onto silica surfaces. Biofunctionality itself is introduced by the biotin, either through the formation of the monolayer or through click chemistry on azide-functionalized SAMs.Said surfaces were then fully characterized using Polarization Modulation Infrared Reflection-Absorption Spectroscopy (PM-IRRAS) an Atomic Force Microscopy (AFM). Bioactivity of biotinylated surfaces was then monitored using streptavidin conjugated with HRP in order to catalyze the redox reaction of chromogenic substrates
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Killian, Manuela S. [Verfasser], and Patrik [Akademischer Betreuer] Schmuki. "Organic Modification of TiO2 and other Metal Oxides with SAMs and Proteins - a Surface Analytical Investigation / Manuela S. Killian. Gutachter: Patrik Schmuki." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2013. http://d-nb.info/1065378084/34.
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Rechmann, Julian [Verfasser], Andreas Gutachter] Erbe, and Axel [Gutachter] [Rosenhahn. "Modification of metal surface electronic properties by phenothiazine-based SAMs / Julian Rechmann ; Gutachter: Andreas Erbe, Axel Rosenhahn ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2020. http://nbn-resolving.de/urn:nbn:de:hbz:294-69146.
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Rechmann, Julian [Verfasser], Andreas [Gutachter] Erbe, and Axel [Gutachter] Rosenhahn. "Modification of metal surface electronic properties by phenothiazine-based SAMs / Julian Rechmann ; Gutachter: Andreas Erbe, Axel Rosenhahn ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/1204258538/34.
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Rouviere, Lisa. "Synthèse organique de silanes fonctionnels et élaboration de monocouches fluorogènes bioconjugables." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0027.
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Dans le cadre de l’élaboration de biocapteurs, des monocouches auto-assemblées (SAMs) fluorogènes pouvant immobiliser un biorécepteur de façon bio-orthogonale et permettre de visualiser la formation du lien covalent entre celui-ci et la surface ont été élaborées. La réaction 1,3-dipolaire de Huisgen entre un azoture et un alcyne a été choisie comme réaction bio-orthogonale. La visualisation de l’immobilisation covalente du biorécepteur se fera par une modulation de la fluorescence. Pour ce faire, deux familles de molécules, les coumarines et les naphthalimides ont été abordées. L’introduction d’une fonction azoture ou alcyne dans une position spécifique permet d’inhiber la fluorescence. Celle-ci pourra alors être libérée lors de l’immobilisation du biorécepteur. Les nouvelles monocouches fonctionnelles fluorogènes ont été caractérisées par infrarouge de réflexion-absorption par modulation de polarisation (PM-IRRAS) pour attester du greffage de l’organosilane et par fluorescence pour suivre la réaction clickAs part of the development of biosensors, fluorogenic self-assembled monolayers (SAMs) that can immobilize a bioreceptor in a bio-orthogonal way revealing the covalent bond between the bioreceptor and the monolayer were elaborated. The Huisgen 1,3- dipolar reaction between an azide and an alkyne was chosen as the bio-orthogonal reaction. The covalent immobilization of the bioreceptor will be visualize by a modulation of the fluorescence. To do this, two families of molecules, coumarines and naphthalimides, have been studied. The introduction of an azide or an alkyne in a specific position quench the fluorescence of the chromophores. The fluorescence will be released after the immobilization of the bioreceptor. New fluorogenic functional monolayers have been characterized by Polarization Modulation-Infrared Reflection-Adsorption Spectroscopy (PM-IRRAS) to confirm the grafting of the organosilanes and by fluorescence to monitor the click reaction
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Liličenko, Nadežda [Verfasser]. "Adsorption kinetic investigations of phthalocyanine derivatives self assembled monolayers (SAMs) on gold: Temperature influence on the SAM formation process and quality / Nadežda Liličenko." Kassel : Universitätsbibliothek Kassel, 2015. http://d-nb.info/1075466954/34.
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Aydogmus, Turkan. "Thermodynamic and transport properties of self-assembled monolayers from molecular simulations." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3080.
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The purpose of the work is to employ molecular simulation to further extend the understanding of Self-Assembled Monolayers (SAMs), especially as it relates to three particular applications: organic-inorganic composite membranes, surface treatments in Micro-Electro-Mechanical Systems (MEMS) and organic-surface-modified Ordered Mesoporous Materials (OMMs).
The first focus area for the work is the use of SAMS in organic-inorganic composite membranes for gas separations. These composite membranes, recently proposed in the literature, are based on the chemical derivatization of porous inorganic surfaces with organic oligomers. Our simulations achieve good qualitative agreement with experiment in several respects, including the improvement in the overall selectivity of the membrane and decrease in the permeance when increasing the chain length. The best improvement in the overall solubility selectivity is reached when the chains span throughout the pore.
The second application focus is on the use of SAMs as coatings in MEMS devices. The work focuses on the modeling of adhesion issues for SAM coatings at the
molecular level. It is shown that as the chain length is increased from 4 to 18 carbon atoms, the adhesion forces between two monolayers at the same separations decreases.
The third application focus is on the use of SAMs for tailoring surface and structural properties of OMMs, in particular, porous silicas. A molecular study of structural and surface properties of a silica material with a 5 nm pore size, modified via chemical bonding of organosilanes with a range of sizes (C4, C8 and C18) is presented. Grand canonical MC simulations are employed to obtain nitrogen adsorption isotherms for unmodified and modified MCM-41 material models. Furthermore, the density profiles of alkyl chains and nitrogen molecules are analyzed to clarify the differences in the adsorption mechanisms in unmodified and modified materials. The position of the capillary condensation steps gradually shifted to lower pressure values with the increase in size of the bonded ligands, and this shift was accompanied by a gradual disappearance of the hysteresis loop. As the length of the bonded ligands is increased, a systematic decrease in the pore diameter is observed and the multi-layer adsorption mechanism in modified model materials diminishes.
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Siurdyban, Elise. "Immobilisation de dérivés du cryptophane-A sur des surfaces planes SiO2/or et or ainsi que sur des nanoparticules magnétiques." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0149/document.
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Les cryptophanes sont des molécules sphériques pouvant encapsuler dans leur cavité lipophile des molécules neutres (halogénométhanes, xénon) mais aussi des espèces ioniques comme les cations césium et thallium. Notre objectif a été d’immobiliser ces cages moléculaires de manière covalente sur un support solide dans le but de créer un matériau capable d’extraire des cations toxiques comme le thallium en milieu aqueux. Différentes stratégies ont été envisagées pour optimiser l’immobilisation de dérivés du cryptophane-A sur des surfaces de silice et d’or (surfaces planes et nanoparticules magnétiques de type coeur-écorce). Les cryptophanes-A mono-acide (1) et hexa-acide(2) ont été immobilisés sur des surfaces de silice préalablement fonctionnalisées par des groupements amines. Le cryptophane-A alcanethiol (3), ainsi que les cryptophanes 1 et 2 modifiés par lacystéamine (respectivement 4 et 5) ont été immobilisés sur des surfaces d’or. La caractérisation des surfaces planes par spectroscopie infrarouge de réflexion-absorption par modulation de polarisation(PM-IRRAS) a permis d’estimer le taux de recouvrement des différentes monocouches de cryptophanes et, ainsi, d’évaluer la méthode d’immobilisation la plus efficace. Un taux de recouvrement proche de 100% a été obtenu pour le cryptophanes 3 immobilisé sur les surfaces d’or.Ce composé a également été immobilisé de façon très efficace sur des nanoparticules magnétiques(γ-Fe2O3/SiO2) enrobées d’une nano-écorce d’or. Ces résultats permettent d’envisager la synthèse d’un cryptophane portant cinq fonctions hydroxyles et une fonction thiol afin de créer des matériaux capables d’extraire des cations toxiquesCryptophanes are spherical molecules that can encapsulate neutral molecules(halogenomethanes, xenon), and ionic species like cesium and thallium cations in their lipophiliccavity. Our objective was to covalently immobilize these molecular cages onto solid substrates tocreate a material able to extract toxic cations such as thallium in aqueous media. Different strategieswere considered to optimize the immobilization of cryptophane-A derivatives onto silica and goldsurfaces (flat surfaces and core-shell magnetic nanoparticles). Mono-acid cryptophane-A (1) andhexa-acid cryptophane-A (2) were immobilized onto silica surfaces that were functionalized by aminogroups beforehand. Alcanethiols cryptophane-A (3), 1 and 2 modified by cysteamine (cryptophanes 4and 5 ,respectively) were immobilized onto gold surfaces. Flat surfaces were characterized bypolarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to estimate thesurface coverage of different cryptophane monolayers and to evaluate the most effective method. Asurface coverage close to 100% was obtained for the cryptophane 3 immobilized onto gold surfaces.This compound has been also immobilized efficiently onto magnetic nanoparticles (γ-Fe2O3/SiO2)coated with gold nano-shell. These results allow to consider the synthesis of cryptophane bearing fivehydroxyl and one thiol functions to create materials able to extract toxic cations
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Cunning, Benjamin V. "An Exploration in Nano-Carbons: Bulk Graphene, Ultrafast Physics, Carbon-Nanotubes." Thesis, Griffith University, 2013. http://hdl.handle.net/10072/367408.
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Carbon nanomaterials encompass the newly discovered allotropes of carbon with at least one of its spatial dimensions on the order of a few nanometers. The physical properties of these nanomaterials differ substantially from the bulk carbon allotropes such as graphite and diamond. Of these nanomaterials, single-walled carbon nanotubes (SWNTs) and graphene have illicited much of the attention owing to their unique and attractive electronic, optical, thermal, and mechanical
properties which have found numerous applications in emerging technologies.
Raman spectroscopy is an invaluable technique in the characterisation of these materials as it allows for both a rapid and non-destructive analysis of these nanomaterials. We examined a number of methodologies for the synthesis of “bulk” quantities of graphene, and using Raman spectroscopy, analysed these samples to critically assess their crystalline quality, finding that many of the bulk methods produce material which could be considered as amorphous, rather than crystalline,
having crystalline domain sizes less than a few nanometers. An important finding, as many of graphene’s unique properties are severely attenuated with increasing defects.
Using these findings, we utilised the non-linear optical properties of graphene, namely its property of saturable absorption (wherby its light absorption decreases with increasing light intensitiy), to create
saturable absorber mirrors (SAMs) which are used in the mode-locking of lasers creating pulses of light on the order femtoseconds with very high peak power. We developed graphene SAMs from the bulk synthetic methods which we found to have good crystalline quality and attempted to use them to passively mode-lock an Er:fiber laser operating at t 1560 nm. We successfully mode-locked the laser with graphene produced from the ultrasound induced exfoliation of graphite generating pules of sub-200 fs duration with low nonsaturable loss, and large modulation depths allowing use in low-gain lasers.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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Ramin, Michael. "Synthèses de nouvelles monocouches auto-assemblées à partir d’organosilanes fonctionnels capables d’auto-association par liaisons hydrogène." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14181/document.
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Il existe une très forte demande en biocapteurs pour la détection d’agents pathogènes dans le domaine environnemental et médical. Dans ce contexte, le contrôle de l’état de surface des biocapteurs joue un rôle crucial. Les monocouches auto-assemblées (Self-Assembled Monolayers, SAMs) permettent de fonctionnaliser de manière homogène et reproductible ces surfaces. Ces SAMs sont généralement obtenues à partir d’agents de couplage siliciés à longue chaîne alkyle. Mais, ces composés sont souvent difficiles à synthétiser et à purifier en raison de leurs faibles solubilités dans les solvants organiques. C’est pour cela que nous avons proposé d’introduire une fonction polaire (amide ou urée) au sein de ces films. Ces fonctions permettent également un auto-assemblage des molécules sur le substrat au moyen de liaisons hydrogène entre les molécules. Les nouvelles monocouches fonctionnelles ont été caractérisées entre autres par spectroscopie infrarouge de réflexion-absorption par modulation de polarisation (PM-IRRAS) ce qui a permis d’identifier les différents groupes moléculaires. Ces monocouches ont aussi montré leurs capacités à immobiliser une molécule biologique (Protéine A)There is an increasing demand for biosensors to detect pathogens in environmental and medical fields. In this context, the control of the surface properties plays an important role. Self-Assembled Monolayers (SAMs) allow to functionalize these surfaces homogeneously and reproducible. SAMs on silicon based surfaces are usually obtained from silylated coupling agents with long alkyl chain. However, these compounds are often difficult to purify owing to their low solubility in organic solvents. That’s why we proposed to introduce a polar function (amide or urea) in the molecular structure. These precursors were also capable of association by H-bonds and offer possibilities to control the organic assembly on the surfaces. The new functional monolayers were characterized by Polarization Modulation Infrared Reflection Adsorption Spectroscopy (PM-IRRAS) and others techniques such as XPS and contact angle in order to identify the different molecular groups on the surface. These functionalized monolayers have also shown their ability to immobilize biomolecules (Protein A)
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Crivillers, Clusella Núria. "Organitzacions bi i tridimensionals de molècules electroactives per aplicacions en dispositius." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/3280.
Full textAbstract:
La preparació de dispositius moleculars amb aplicacions específiques ha atret una gran atenció durant aquests darrers anys, ja que aquests poden oferir nous avantatges respecte la tecnologia basada en l'òxid de silici. Sovint, per la preparació dels dispositius és necessari dipositar les molècules o material sobre un suport sòlid adequat. L'ordenament i l'empaquetament de les molècules són aspectes crucials per la operació del dispositiu i, per tant, és molt important tenir un bon control de com el dissolvent, el substrat i la funcionalització molecular influeixen en les organitzacions moleculars resultants i en les interaccions intermoleculars. En aquesta Tesi s'han estudiat les organitzacions de dues famílies d'espècies electroactives, els tetratiafulvalens (TTFs) i els radicals policlorotrifenilmetílics (PTMs), que s'han utilitzat per la preparació de transistors orgànics d'efecte de camp (OFETs) i interruptors moleculars, respectivament.
Els OFETs estan inclosos dintre del que es coneix com l'electrònica dels plàstics. Alguns derivats de TTFs posseeixen unes característiques electròniques i estructurals apropiades per ser utilitzats com a semiconductors orgànics per OFETs. En aquesta Tesi es descriuen els principals resultats obtinguts en la síntesi i estudi de les propietats elèctriques com a OFETs dels derivats de TTF ditiofetetratiafulvalè (DT-TTF) i el dibenzotetratiafulvalè (DB-TTF). OFETs basats en cristalls que han estat processats a partir de solució, han donat mobilitats molt altes d'1 i 3.65 cm2/Vs, pel DB-TTF i el DT-TTF, respectivament. S'han preparat pel·lícules altament ordenades del DT-TTF utilitzant la tècnica de Zone Casting, i s'han obtingut mobilitats de l'ordre del silici amorf i, per tant, amplien la possibilitat d'utilizar-los en l'electrònica de baix cost.
Ja que la miniaturització dels dispositius és un dels principals objectius de l'electrònica molecular, la possibilitat de fabricar-los amb un nombre reduït de molècules és una aproximació molt atractiva. Amb aquesta finalitat, s'han preparat monocapes auto-assemblades (SAMs) basades en radicals PTM. Aquestes compostos són espècies multifuncionals ja que combinen propietats òptiques, magnètiques i electroquímiques. Les SAMs s'han preparat sobre substrats derivats del SiO2 i Au. S'ha demostrat el comportament com a interruptor molecular (químic i electroquímic) dels substrats funcionalitzats amb radicals PTM i s'ha utilitzat la resposta òptica o magnètica per llegir l'estat de l'interruptor.
D'altra banda, també s'ha estudiat per microscòpia de força atòmica (AFM) i microscòpia d'efecte túnel (STM) el tipus d'organització que formen alguns derivats de TTF i PTM fisisorbits sobre substrats de diferent naturalesa (grafit, mica i SiO2). L'auto-assemblatge sobre grafit d'un derivat de radical PTM funcionalitzat amb tres cadenes alquíliques llargues ha donat lloc a la formació d'estructures tipus fibril·lars altament ordenades, formades per files magnètiques separades per les cadenes alquíliques, que actuen com a barreres diamagnètiques. En el cas dels TTFs, s'ha estudiat l'organització bi i tridimensional del tricarbometoxitetratiafulvalè (TCM-TTF). S'ha observat que les interaccions molècula-molècula, molècula-substrat i molècula-dissolvent tenen un paper molt important en l'organització resultant, formant-se des de capes fins a fibres moleculars.
The construction of molecular devices with specific applications has attracted a great deal of attention in recent years since they can offer new advantages to well-established silicon-based technologies. Often, to construct a molecular device it is necessary to deposit molecules or material on a suitable substrate. Since the ordering and packing of the molecules are crucial aspects for the operation of the device, it is important to have good control of how solvent, substrate or molecular funcionalitzation influences on the resulting molecular assemblies and the intermolecular interactions.
In this Thesis we have studied the organizations of two families of electroactive molecules, tetrathiafulvalenes (TTFs) and polychlorotriphenylmethyl (PTM) radicals, which have been used as the active components of Organic Field Effect Transistors (OFETs) and molecular switches, respectively.
OFETs are included in the field of Plastic Electronics. Some TTF derivatives have appropriate structural and electronic characteristics to be used as organic semiconductors in OFETs. The main results related to the synthesis and the electrical properties as OFETs of the dithiophene-tetrathiafulvalene (DT-TTF) and dibenzo-tetrathiafulvalene (DB-TTF) are described in this Thesis. OFETs based on single crystals obtained from solution of these synthesized compounds have resulted in mobilities of 1 cm2/Vs and 3.6 cm2/Vs, for DB-TTF and DT-TTF, respectively, being the later the highest mobility reported for solution-processed devices. Highly ordered films based on DT-TTF were prepared by Zone Casting exhibiting also high mobilities, of the order of 0.2 cm2/Vs. Thus, this technique offers a promising approach to obtain low-cost devices with large area coverage.
Since the miniaturization of the devices is one of the main aim in the field of molecular electronics, the possibility to fabricate a device with a small group of molecules is a very attractive approach. With this purpose, self-assembled monolayers (SAMs) based on PTM radicals have been prepared. These are multifunctional species that combine optical, magnetic and electrochemical properties. SAMs of PTM radicals have been formed on silicon dioxide-based substrates and gold. It has been demonstrated that the resulting functionalized substrates can be used as molecular switches (chemical and electrochemical), using the optical and magnetic response to read the status of the switch.
We have also studied by AFM and STM the self-assembly of some TTFs and PTMs derivatives physisorbed on surface. A new PTM radical bearing long alkyl chains was synthesized and its self-assembly on graphite was studied by STM at the liquid-solid interface. The self-assembly of this PTM radical gave highly-ordered structures composed by magnetic double rows, formed by the PTM cores, separated by the alkyl chains that act as insulating diamagnetic barriers and determine the spacing between the rows. On the other hand, we have studied the organization of the tetra(carbometoxy)-tetrathiafulvalene (TCM-TTF) and it was observed that depending on the combination of the two main parameters (solvent and substrate) the resulting two-dimensional assemblies can be completely different, ranging from molecular layers to long molecular fibers.
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Kleinert, Mike [Verfasser]. "Cluster-Glycoside als Bausteine für selbstanordnende Monoschichten (SAMs) : Glyco-SAMs als Glycocalix-Mimetika / vorgelegt von Mike Kleinert." 2005. http://d-nb.info/977247546/34.
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Lin, Tzung-Han, and 林宗翰. "Silicon nanoelectronic sensors with SAMs selective surface passivation." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01757342341900179060.
Full textAbstract:
碩士國立交通大學
材料科學與工程學系奈米科技碩博士班
101
In this study, selective ablation of self-assembly monolayer methoxy-poly (ethylene glycol) silane (MPEG-sil) and Octadecyltrichlorosilane (OTS) on silicon nanoelectronic devices by localize joule heating was demonstrated for biosensing application. Lightly doped region in a silicon nanoelectronic device is usually functioned as the active channel which is sensitive to the change of surface potential. And, the resistance of this region is higher compared to other regions in a device so that the electric power consumed. SAMs on lightly doped region were ablated during Joule heating leaving the rest area passivated. The subthreshold swing of nanoelectronic device almost kept unchanged after Joule heating. AFM was adopted to characterize the device surface before and after Joule heating and selective biomolecule modifications. Analysis of fluorescent results showed consistency with AFM results that selectivity in surface modofications was achieved. We found that SAM-ablated device possess potential in the increase of sensing response and in the increase of sensitivity for low concentration detection. In streptavidin detection, the device with selective modification exhibited a detection limits of 15 pM, while the device without selective modification showed an order of magnitude higer in its limit of detection.
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Chang, Yi-Cheng, and 張義正. "Studies of Nanoscale Organic Molecules SAMs on ITO-Glass." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/94292554066847065539.
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碩士淡江大學
化學學系碩士班
98
Some nanoscale organic molecules were designed based on the combination of thiophenyl and phenyl structures. A series of designed compounds was successfully synthesized and theirs (SAM) formations on ITO-glass also were achieved. The conductance of these SAMs were measured by conductive Atomic Force Microscopy (c-AFM) technology. The experimental results showed that the conductivity values were determined by the contact surface structure of its SAM.
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TSAI, MENG-TING, and 蔡孟廷. "Study of Work Function Modulation with Self-Assembled Monolayers（SAMs）." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/f3s48e.
Full textAbstract:
碩士國立中正大學
化學暨生物化學研究所
105
The purpose of this research is to find a self-assembled monolayer system to modify gold surface and maximize the change in its work function, so as to facilitate charge injection in organic electronic devices when using the metal as electrode. The change of work function relates to the dipole moment of the molecule used to modify the electrode surface along the surface normal. However, the CF3SO2BnCH2SH (dipole : 6.52 debye) -modified Au has lower work function(work function : 5.33 eV) than CF3BnCH2SH(dipole : 3.99 debye) -modified Au (work function : 5.81 eV). It is presumed that with higher dipole of molecule, there is stronger electrostatic repulsion between molecules so that either a closely-packed monolayer cannot be formed or the direction of the dipole is pushed away from the normal of the surface. To reduce the repulsion, two methods are proposed. One is to use mixed monolayer containing molecules with the same terminal functional group but with different molecular length. The other is to improve the intermolecular attractions in a mixed layer with electron-poor and electron-rich arenes. In specific mixing ratios, both methods can achieve a work function higher than what a single component monolayer can achieve. It is worth noting that in the former one, the adsorption density of mixed monolayer is ~10% more than single component monolayer by cyclic voltammetry and X-ray photon spectrum.
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Lee, Tzu-Nien, and 李子念. "The Study of SAMs/SiO2 Stacked Sensing Membrane for ISFETs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/45925080917437867195.
Full textAbstract:
碩士國立暨南國際大學
電機工程學系
101
In this thesis, the SAM/SiO2 stacked sensing membrane was used to improve the sensing characteristic of ISFETs. In our results, the sensitivity, hysteresis and drift of EIS with the SAM/SiO2 stacked sensing membrane were all improved. Besides, the sensitivity of ISFETs was also improved .This technology will be suitable for the future high sensitivity ISFETs.