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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Plasma Characteristics of the DC Saddle Field Glow Discharge

Leong, Keith R. 10 January 2014 (has links)
Plasma enhanced chemical vapor deposition systems are massively deployed to grow numerous thin film coatings including hydrogenated amorphous silicon. A new deposition chamber was designed, procured, and constructed to investigate the plasma properties of a 100% silane (SiH4) glow discharge with varying chamber pressure and inter-electrode spacing. A Hiden EQP1000 ion mass spectrometer sampled the plasma from the substrates point of view. Ion energy distributions were obtained using four different excitation sources +DC, –DC, radio frequency (at 13.56 MHz), and the DC Saddle Field (DCSF) in the tetrode configuration. The shape of the ion energy distributions was constant for the capacitively coupled +DC, –DC, and rf (at higher pressures of 75 and 160 mTorr) glow discharges. The shape of the ion energy distributions for the DCSF plasma exhibited a double peak or saddle structure analogous to radio frequency plasmas. The width between the peaks (peak separation) was controlled by the pressure and the semi-transparent cathode to semi-transparent anode distance. Ion energy distributions from the DCSF plasma concurred with rf and +DC ion energy distributions at specific pressures and inter-electrode distances. This result demonstrates the versatility of the DCSF glow discharge system. Moreover, control of the peak separation is modeled to be iii equivalent to controlling the critical ratio (ion transit time in the sheath to the electron oscillating period), and/or the inferred electron oscillating sheath potential. The DCSF possesses a fusion of rf and +DC methods. The long high energy tail or constant background are indicative of a +DC high voltage sheath in which there is an increasing fraction of collisionless ions as the anode-cathode distance increases. These collisionless ions are provided by the oscillating electrons (or rf nature) of the DCSF method. Higher order silane (silicon containing) ions increase in relative intensity with increasing inter-electrode spacing for the +DC, –DC, and rf plasmas. These higher order silane ions are also detected in the DCSF plasma, and can be reduced at either lower pressure or lower cathode to anode or cathode to substrate distances.
192

Plasma Characteristics of the DC Saddle Field Glow Discharge

Leong, Keith R. 10 January 2014 (has links)
Plasma enhanced chemical vapor deposition systems are massively deployed to grow numerous thin film coatings including hydrogenated amorphous silicon. A new deposition chamber was designed, procured, and constructed to investigate the plasma properties of a 100% silane (SiH4) glow discharge with varying chamber pressure and inter-electrode spacing. A Hiden EQP1000 ion mass spectrometer sampled the plasma from the substrates point of view. Ion energy distributions were obtained using four different excitation sources +DC, –DC, radio frequency (at 13.56 MHz), and the DC Saddle Field (DCSF) in the tetrode configuration. The shape of the ion energy distributions was constant for the capacitively coupled +DC, –DC, and rf (at higher pressures of 75 and 160 mTorr) glow discharges. The shape of the ion energy distributions for the DCSF plasma exhibited a double peak or saddle structure analogous to radio frequency plasmas. The width between the peaks (peak separation) was controlled by the pressure and the semi-transparent cathode to semi-transparent anode distance. Ion energy distributions from the DCSF plasma concurred with rf and +DC ion energy distributions at specific pressures and inter-electrode distances. This result demonstrates the versatility of the DCSF glow discharge system. Moreover, control of the peak separation is modeled to be iii equivalent to controlling the critical ratio (ion transit time in the sheath to the electron oscillating period), and/or the inferred electron oscillating sheath potential. The DCSF possesses a fusion of rf and +DC methods. The long high energy tail or constant background are indicative of a +DC high voltage sheath in which there is an increasing fraction of collisionless ions as the anode-cathode distance increases. These collisionless ions are provided by the oscillating electrons (or rf nature) of the DCSF method. Higher order silane (silicon containing) ions increase in relative intensity with increasing inter-electrode spacing for the +DC, –DC, and rf plasmas. These higher order silane ions are also detected in the DCSF plasma, and can be reduced at either lower pressure or lower cathode to anode or cathode to substrate distances.
193

Biochemical functionalization of silicon dioxide surfaces for sensing applications / Biochemische Funktionalisierung von Siliziumdioxidoberflächen für sensorische Anwendungen

Römhildt, Lotta 21 July 2014 (has links) (PDF)
The aim of this work was to functionalize silicon dioxide surfaces with biochemical molecules in such a way that biorecognition of target molecules in solution will be possible. By introducing a tool set of different molecules and characterization methods, a more universal approach towards various biosensor setups is presented. This includes on the one hand preparation of the biosensor surfaces to allow further molecule attachment via their reactive functional groups. Secondly, the selection of chemical molecules providing suitable counterparts for abundant functional groups of potential receptors is discussed. Two detection schemes are introduced – based on an antibody to detect the antibiotic amoxicillin and aptamers to detect thrombin. The antibody was implemented in an inverse competition assay to probe such small target molecules. Antibiotic residues are often present in wastewater. Aptamers, so-called artificial antibodies, were selected as they provide many advantages over antibodies. As a model system, two different thrombin binding aptamers were chosen which allowed to perform sandwich assays as well. The protein thrombin plays an important role in the blood coagulation cascade. To probe the individual modification steps, different techniques for analysis were applied. Surface micropatterning was introduced to improve recognition of modified areas and fluorescence-to-background ratios resulting in a thrombin detection limit down to 20 pM. One important goal was the integration in ion-sensitive field-effect transistor devices. Aptamers are small in size which might enable a higher sensitivity of these devices compared to the use of antibodies because of the Debye layer thickness. As a final step, first measurements towards silicon nanowire based field-effect transistor biosensors were carried out on devices with bottom-up and top-down fabricated nanowires using both proposed receptor-analyte combinations. The potential of these devices as portable sensors for real-time and label-free biosensing is demonstrated. / Ziel dieser Arbeit war es Siliziumdioxidoberflächen so mit biochemischen Molekülen zu funktional- isieren, dass die biologisch spezifische Erkennung von Zielmolekülen in Lösung möglich wird. Hier wird eine Auswahl an geeigneten Molekülen und Charakterisierungsmethoden für einen vielseitigen Ansatz gezeigt, der auf verschiedene Biosensorsysteme anwendbar ist. Das beinhaltet zum Einen die Präparation der Biosensoroberflächen, so dass die Moleküle über reaktive funktionelle Gruppen angebunden werden können. Als zweites ist die Auswahl der chemischen Moleküle wichtig, da diese die passenden Gegenstücke zu potentiellen funktionellen Gruppen der Rezeptoren darstellen. Zwei verschiedene Detektionsvarianten werden eingeführt – Antikörper gegen das Antibiotikum Amoxicillin und Aptamere gegen Thrombin. Der Antikörper wurde in einen inversen Wettbewerbsassay integriert um einen solch kleinen Ana- lyten detektieren zu können. Rückstände von Antibiotika sind häufig in Abwässern zu finden. Ap- tamere, sogenannte künstliche Antikörper, weisen gegenüber Antikörpern viele Vorteile auf. Als ein Modellsystem wurden zwei unterschiedliche Thrombin bindende Aptamere verwendet, was auch die Durchführung von Sandwich Assays ermöglichte. Das Protein Thrombin spielt eine wichtige Rolle bei der Blutgerinnung. Um die einzelnen Modifikationsschritte zu untersuchen, wurden verschiedene Charakterisierungsmethoden angewendet. Die Mikrostrukturierung der Funktionalisierung erleichterte die Erkennung der modifizierten Flächen und verbesserte das Fluoreszenz-zu-Hintergrund Verhältnis. Das führte zu einer Detektionsgrenze von 20 pM für Thrombin. Ein wichtiges Ziel dieser Arbeit war die Integration der Funktionalisierung in einen ionen-sensitiven Feldeffekttransistor. Die kleinen Aptamere könnten dabei aufgrund der geringen Debye-Schichtdicke bei diesen Sensoren eine höhere Sensitivität als mit Antikörpern ermöglichen. Zuletzt wurden erste Messungen hin zu Silizium Nanodraht basierten Feldeffekttransistor Biosen- soren mit beiden untersuchten Rezeptor-Analyt-Kombinationen durchgeführt. Sowohl die Chips mit bottom-up als auch mit top-down gewachsenen Nanodrähten zeigen dabei ihr Potential als handliche Sensoren zur markerfreien Detektion in Echtzeit.
194

Preparation And Characterization Of Glass Fiber Reinforced Poly(ethylene Terephthalate)

Altan, Cansu 01 July 2004 (has links) (PDF)
Glass fiber reinforced poly(ethylene terephthalate), GF/PET has excellent potential for future structural applications of composite materials. PET as a semi-crystalline thermoplastic polyester has high wear resistance, low coefficient of friction, high flexural modulus and superior dimensional stability make it a versatile material for designing mechanical and electromechanical parts. Glass fibers are currently used as strength giving material in structural composites because of their high strength and high performance capabilities. In order to obtain high interfacial adhesion between glass fiber and polymer, glass fibers are treated with silane coupling agents. The objective of this study is to produce GF/PET composites with varying glass fiber concentration at constant process parameters in a twin screw extruder. Also, by keeping GF content constant, it is aimed to observe the effects of process parameters such as screw speed and feed rate on structural properties of the composites. Another objective of the study is to investigate the influence of different coupling agents on the morphological, thermal and mechanical properties and on fiber length distributions of the composites. Tensile strength and tensile moduli of the GF/PET composites increased with increasing GF loading. There was not a direct relation between strain at break values and GF content. The interfacial adhesion between glass fiber received from the manufacturer and PET was good as observed in the SEM photograps. Degree of crystallinity values increased with the addition of GF. Increasing the screw speed did not affect the tensile strength of the material significantly. While increasing the feed rate the tensile strength decreased. The coupling agent, 3-APME which has less effective functional groups than the others showed poor adhesion between glass fiber and PET. Therefore, lower tensile properties were obtained for the composite with 3-APME than those of other silane coupling agents treated composites. Number average fiber length values were reduced to approximately 300&amp / #61549 / m for almost all composites prepared in this study.
195

Designing functional magnetic nanoparticles with flame spray pyrolysis for bio-applications

Li, Dan, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2009 (has links)
Magnetic nanoparticles (MNPs) hold great promise in the fields of biology and medicine. The synthesis of functional MNPs with precisely controlled crystallographic, physicochemical, and magnetic properties on a large scale still remains the challenge today. This thesis reports the exploration of liquid-fed flame spray pyrolysis (FSP) in the synthesis of functional MNPs, their surface modifications, and potential bio-applications. Superparamagnetic and ferromagnetic maghemite (γ-Fe2O3) nanoparticles, and silica-coated maghemite (SiO2/γ-Fe2O3) nanocomposites were synthesised using FSP. The size of γ-Fe2O3 was controllable from 6 to 53 nm, with morphology evolving from a disordered near-spherical shape to fully ordered 2-D hexagonal/octagonal platelet. The saturation magnetisation (Ms) increased from 21 to 74 emu/g with increasing particle size, up to 13 nm when Ms approached the bulk γ-Fe2O3 characteristics. In the case of SiO2/γ-Fe2O3, three distinct morphologies, namely the single segregated γ-Fe2O3 core- SiO2 shell, transitional mixed morphologies, and multi γ-Fe2O3 cores embedded in submicron SiO2 shell, were obtained. The core size, composite size, and morphology of γ- Fe2O3 were tunable by varying %SiO2 loading and the use of a quartz tube enclosure during flame synthesis. The magnetic behaviour correlated well with the crystal microstructure. Following the core particle design, protein adsorption-desorption behaviour on FSP-madeMNPs was studied. Bovine serum albumin (BSA) adsorption was found to follow the Langmuir isotherm, with high binding capacities (150−348 mg BSA/g particle) and fast association constants. Electrostatically governed BSA orientations were proposed for different particle-buffer systems. The adsorbed BSA was effectively recovered by pH-shift using K2HPO4. Subsequently, terminal amine, aldehyde, carboxylic, epoxy, mercapto and maleimide functionality were anchored onto the FSP-made γ-Fe2O3 particles. These versatile functional groups led to conjugation of active trypsin. The immobilised trypsin exhibited superior durability with >60% residual activity after one week, and excellent reusability for >5 cycles. The trypsin-conjugated MNPs are promising carriers in proteomics, demonstrating good substrate specificity with equivalent or better sequence coverage compared to free trypsin in insulin and BSA digestion. In another application, a refined silanisation procedure simultaneously reduced γ-Fe2O3 to Fe3O4, and generated thiol enriched surface for matrix metalloproteinase-2 (MMP-2) conjugation. The highly active MMP-2-conjugated MNPs could potentially enhance the interstitial transport of macromolecule/nanoparticles in drug delivery.
196

Efeito da temperatura de secagem de dois tipos de silano e da supressão ou redução do tempo de condicionamento com ácido hidrofluorídrico na resistência de união entre uma cerâmica de dissilicato de lítio e um cimento resinoso / Effect of drying temperature of two silan types and elimination or reduction of conditioning hydrofluoridric acid time with the bond strenght between a lithium disilicate ceramic and a resin cement

Leticia Monteiro Peixoto 24 August 2012 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Este estudo avaliou o efeito de diferentes métodos de silanização e aplicação do ácido hidrofluorídrico (HF) sobre a resistência à microtração de uma cerâmica de dissilicato de lítio a um cimento resinoso. Quarenta blocos de IPS e.max Press /Ivoclar Vivadent (5x5x6mm) foram cimentados a blocos de resina Z250/3M ESPE (5x5x6mm) usando o cimento resinoso RelyX ARC/3M ESPE de acordo com os seguintes métodos de tratamento superficial: G1: 20s de ácido fluorídrico (HF) + silano não hidrolisado Primer-Activactor/Dentsply (SNH) seco à temperatura ambiente; G2: 20s HF + silano pré-hidrolisado RelyX Ceramic-Primer/3M ESPE (SPH) seco à temperatura ambiente; G3: 10s HF + SNH seco com ar quente (50oC-2min); G4: 10sHF + SPH seco com ar quente (50oC-2min); G5: sem ácido, SNH seco com ar quente (50oC-2min); G6: sem ácido, SPH seco com ar quente (50oC-2min); G7: sem ácido, SNH seco à temperatura ambiente; G8: sem ácido, SPH seco à temperatura ambiente. Antes de cada método de silanização, os blocos cerâmicos receberam acabamento com lixas de carbeto de silício (220-600) e limpeza com ácido fosfórico 37% (1min). A cimentação foi realizada com carga vertical de 1kg por 10min. Os conjuntos de cerâmica/cimento/resina foram armazenados em água destilada (37C) por 24 horas e depois seccionados em máquina de corte Isomet 1000 a fim de obter palitos (n = 40) de 1mm2 de área da seção transversal, que foram submetidos ao teste de microtração em máquina de ensaio universal Emic (v = 0,5mm/min). O modo de fratura foi avaliado em microscópio eletrônico de varredura. A análise estatística foi realizada utilizando ANOVA / Dunnett (p-valor = 0,000). As médias MPa e desvio padrão foram: G1-21,5 (8,9) BC; G2-30,5 (7,2) A; G3-19.4 (9.1) BC; G4-24,0 (9,0) B; G5-8.1 (3.2) D; G6 -18,0 (6,2) C; G7-7.8 (2,6) D; G8-6.3 (2,5) D. Grupos 2, 3, 4 e 6 não tiveram falhas prematuras dos palitos contra os grupos 1, 5, 7 e 8, que apresentaram 2,2; 44,4; 75,6 e 33,3% de perdas prematuras, respectivamente. O teste de correlação foi realizado apresentando significância estatística, com valor de -0,736 (p-valor = 0,000), mostrando que, a medida que o percentual de perda prematura aumenta, a média da MPa diminui. Quanto ao modo de fratura, observou-se 44,97% de falhas do tipo mista, 51,70% de falhas do tipo adesiva, 3,33% de falhas do tipo coesiva do cimento. Quando é realizada a supressão do condicionamento com HF como pré-tratamento da superfície cerâmica IPS e.max Press, a aplicação de silano SPH, associada ao seu tratamento térmico, deve ser o método de silanização recomendado, embora os valores mais elevados de resistência de união tenham sido os obtidos quando utilizado o condicionamento com HF por 20s. Quando é realizada a redução do tempo de condicionamento com HF para 10s, a aplicação do silano (SPH ou SNH) deve ser sempre associada ao seu tratamento térmico. O SNH só deve ser usado se as superfícies das cerâmicas IPS e.max Press forem tratadas com HF. / This study devaluated the effect of different types of silanization and hydrofluoric acid on the microtensile bond strength of a lithium dissilicate ceramic system. Forty IPS e.max Press /Ivoclar Vivadent blocks (5x5x6mm) were cemented to Z250/3M ESPE resin blocks (5x5x6mm) using RelyX ARC/3M ESPE resin-cement according to the following silanization methods: G1: 20s hydrofluoric acid (HF) + non-hydrolyzed silane Primer-Activactor/Dentsply (NHS) dried at room temperature; G2: 20sHF + pre-hydrolyzed silane RelyX Ceramic-Primer/3M ESPE (PHS) dried at room temperature; G3: 10sHF + NHS dried with hot air (50oC-2min); G4: 10sHF + PHS + hot air; G5: NHS + hot air; G6: PHS + hot air; G7: NHS dried at room temperature; G8: PHS dried at room temperature. Before each silanization method, all ceramic blocks were abraded with SiC grit papers (220-600) and cleaned with 37% phosphoric acid (1min). The cementation was made with vertical load of 01 kg for 10 min. After cementation procedure, all ceramic/ciment/resin blocks were stored in distilled water (37oC) for 24h before being cut to obtain stick-shapped specimens (n=45) of approximately 1mm2 cross-sectional area for microtensile test (v=0.5mm/min). Statistical analysis was performed using ANOVA/Dunnett (p-value = 0,000). The mean MPa(SD) values were: G1-21.5(8.9)BC; G2-30.5(7.2)A; G3-19.4(9.1)BC; G4-24.0(9.0)B; G5-8.1(3.2)D; G6-18.0(6.2)C; G7-7.8(2.6)D; G8-6.3(2.5)D. Groups 2, 3, 4 and 6 had no sticks premature fail against groups 1, 5, 7 and 8, that had 2.2, 44.4, 75.6 and 33.3% of sticks premature fails, respectively. As the correlation coefficient was statistically significant, -0.736 (p-value = 0.000), it could be argued that as the percentage of premature loss increased the MPa mean decreases. The failure mode was 44.97% of mixed failures, 51.70% of adhesive failures, 3.33% of cohesive failures of the cement. When the pretreatment is performed without HF conditioning of the IPS e.max Press ceramic surface, then PHS with hot air application should be the silanization method recommended, although higher bond strength values were obtained when HF conditioning for 20s was used with this type of silane. When the time of HF conditioning is reduced for 10 sec, the application of silane (SPH or SNH) must be always related to its heat treatment. NHS should only be used if IPS e.max Press ceramic surfaces are treated with HF.
197

Studies Of Thermal, Nanomechanical And Tribological Characteristics Of Perfluoroalkyl Silanes Self Assembled On Aluminum Surfaces

Devaprakasam, D 04 1900 (has links) (PDF)
No description available.
198

Towards bottom-up silicon nanowire-based biosensing:: Innovative concepts for fabricating lab-on-a-chip devices

Gang, Andreas 09 March 2018 (has links)
The term "Lab-on-a-Chip" (LoC) describes highly miniaturized systems in which the functionalities of entire laboratories are scaled down to the size of transportable microchips. Particularly in the field of chemical and bio-analysis, such platforms are desired for a fast and highly sensitive sample analysis at the point of care. This work focuses on silicon nanowire (SiNW) based sensors. Innovative device fabrication concepts are developed from various directions, for a facile and reliable assembly of LoC analysis systems. Firstly, a multifunctional microfluidic set-up is developed which allows for a facile reversible sealing of channel structures on virtually any kind of substrate while maintaining the possibility of a rapid prototyping of versatile channel designs and the applicability of high working pressures of up to 600 kPa. Secondly, a 3-(triethoxysilyl)propylsuccinic anhydride (TESPSA) based surface modification strategy for the attachment of specific receptor molecules without additional binding site passivation is explored. Thirdly, bottom-up grown SiNWs are utilized for producing parallel arrays of Schottky barrier field-effect transistors (FETs) via contact printing. Using the initially developed microfluidic set-up, the concept of the TESPSA-based receptor immobilization is proved via fluorescence microscopy and by applying the SiNW FETs as biosensors. Using a receptor-analyte system based on a set of antibodies and a peptide from human influenza hemagglutinin, it is shown that antibodies immobilized with the developed method maintain the specificity for their antigens. The fourth major research field in this work is the microfluidics-based alignment of one-dimensional nanostructures and their deposition at predetermined trapping sites for reliably fabricating single NW-based FETs. Such devices are expected to provide superior sensitivity over sensors based on parallel arrays of FETs. Consequently, within this work, innovative LoC devices fabrication approaches over a broad range of length scales, from micrometer scale down to the molecular level, are investigated. The presented methods are considered a highly versatile and beneficial tool set not only for SiNW-based biosensors, but also for any other LoC application. / Unter dem Begriff „Lab-on-a-Chip“ (LoC) fasst man stark miniaturisierte Systeme zusammen, die die Fähigkeiten eines ganzen Labors auf einen transportablem Mikrochip übertragen. Insbesondere im Bereich der Analyse chemischer und biologischer Proben werden solche Plattformen bevorzugt eingesetzt, da sie direkt am Ort der Probenentnahme schnelle, hoch sensible Messungen ermöglichen. Im Mittelpunkt dieser Doktorarbeit stehen Sensoren auf Basis von Siliziumnanodrähten (SiNWs). Auf verschiedenen Gebieten werden innovative Konzepte zur einfachen und zuverlässigen Herstellung von LoC Systemen entwickelt. Zu Beginn wird ein multifunktionaler Mikrofluidik-Aufbau vorgestellt, der ein einfaches reversibles Verschließen von Mikrofluidik-Kanälen auf nahezu allen möglichen Substraten erlaubt. Der Aufbau ermöglicht das schnelle Anfertigen und Testen verschiedener Kanalstrukturen sowie das Betreiben von Fluidik-Experimenten mit hohen Arbeitsdrücken von bis zu 600 kPa. Der zweite Schwerpunkt der Arbeit ist die Entwicklung einer Methode zur Funktionalisierung von Sensor-Oberflächen mittels 3-(Triethoxysilyl) Propyl Bernsteinsäure Anhydrid (TESPSA) für die Immobilisierung spezifischer Rezeptormoleküle. Bei dieser Methode entfällt die Notwendigkeit einer zusätzlichen Passivierung ungenutzter Anbindungsstellen. Des Weiteren erfolgt die Herstellung von Parallelschaltungen von Schottky-Barrieren-Feld-Effekt-Transistoren (SB-FETs) aus „bottom-up“ gewachsenen SiNWs durch mechanisches Abreiben der SiNWs vom Wachstumssubstrat auf ein Empfängersubstrat. Unter Verwendung des eingangs entwickelten Mikrofluidik-Aufbaus wird die prinzipielle Anwendbarkeit der TESPSA-basierten Rezeptor-Immobilisierung nachgewiesen, sowohl anhand von Fluoreszenzmikroskopie-Untersuchungen als auch mit Hilfe der SiNW FETs als Biosensoren. Mittels eines Rezeptor-Analyt-Systems, bestehend aus verschiedenen Antikörpern und einem Peptid des Influenzavirus A, wird gezeigt, dass Antikörper, die über TESPSA an Oberflächen gebunden werden, ihre Spezifizität für ihre Antigene beibehalten. Der vierte große Forschungsabschnitt dieser Arbeit widmet sich der mikrofluidischen Ausrichtung eindimensionaler Nanomaterialien und deren Ablage an vorgegebenen Fangstellen, wodurch eine zuverlässige Herstellung von FETs aus Einzelnanodrähten erreicht wird. Es wird davon ausgegangen, dass Einzelnanodraht-FETs gegenüber Parallelschaltungen von Nanodraht-FETs verbesserte Sensoreigenschaften aufweisen. Folglich beinhaltet diese Arbeit viele zukunftsweisende Ansätze für die Herstellung von LoC Systemen. Untersuchungen über eine Bandbreite von Längenskalen, von Mikrometer großen Strukturen bis hinab zur molekularen Ebene, werden präsentiert. Es wird davon ausgegangen, dass die vorgestellten Methoden als eine vielfältige Sammlung von Werkzeugen nicht nur bei der Herstellung von Biosensoren auf SiNW-Basis Einsatz finden, sondern ganz allgemein den Aufbau verschiedenster LoC Systeme vorantreiben.
199

Dynamic Heterogeneity Analysis of Silica Reinforced SBR Using X-ray Photon Correlation Spectroscopy

Huang, Zheng 03 May 2021 (has links)
No description available.
200

Chemical Templating by AFM Tip-Directed Nano-Electrochemical Patterning

Nelson, Kyle A. 14 December 2011 (has links) (PDF)
This work has examines the creation and use of chemical templates for nanocircuit and other nanodevice fabrication. Chemical templating can be useful in attachment, orientation and wiring of molecularly templated circuits. DNA origami provides a suitable method for creating molecularly templated circuits as DNA can be folded into complex shapes and functionalized with active circuit elements, such as semiconducting nanomaterials. Surface attachment of DNA origami structures can be accomplished by hybridization of dangling single-stranded DNA (ssDNA) on the origami structures with complementary surface-bound strands. Chemical templating provides a pathway for placing the patterned surface-bound attachment points needed for surface alignment of the molecular templates. Chemical templates can also be used to connect circuit elements on the surface by selectively metallizing the templates to form local wiring. AFM tip-directed nano-oxidation was selected as the method for patterning to create chemical templates. This project demonstrates new techniques for creating, continuous metallization of, and DNA attachment to nanochemical templates. Selective-continuous metallization of nanochemical templates is needed for wiring of circuit templates. To improve the metallization density and enable the continuous nano-scale metallization of amine-coated surfaces, the treatment of amine-coated surfaces with a plating additive prior to metallization was studied. The additive treatment resulted in a 73% increase in seed material, enabling continuous nano-scale metallization. A new method was developed to create amine nanotemplates by selective attachment of a polymer to surface oxide patterns created by nano-oxidation. The treatment of the templates with the additive enabled a five-fold reduction in feasible width for continuous metallization. Nano-oxidation was also used in the nanometer-scale patterning of a thiol-coated surface. Metallization of the background thiols but not the oxidized patterns resulted in a metal film that was a negative of the patterns. The resulting metal film may be useful for nanometer-scale pattern transfer. DNA-coated gold nanoparticles (AuNPs) were selectively attached to amine templates by an ionic interaction between the template and ssDNA attached to the particles. Only the ssDNA on the bottom of the AuNPs interacted with the template, leaving the top strands free to bind with complementary ssDNA. Attempts to attach origami structures to these particles were only marginally successful, and may have been hindered by the presence of complementary ssDNA in solution but not attached to the origami, or the by the low density of DNA-AuNPs attached to the templates. The formation of patterned binding sites by direct, covalent attachment of ssDNA to chemical templates was also explored. Initial results indicated that ssDNA was chemically bound to the templates and able to selectively bind to complementary strands; however, the observed attachment density was low and further optimization is required. Methods such as these are needed to enable nano-scale, site-specific alignment of nanomaterials.

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