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Biodiesel production over supported zinc oxide nano-particlesMukenga, Mbala 10 April 2013 (has links)
M.Tech. (Chemical Engineering) / Please refer to full text to view abstract
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Design and evaluation of hybrid plasmonic nanostructures towards materialization of SERS sensorsHoang, Phuong 10 1900 (has links)
Optical sensors based on Surface-enhanced Raman scattering (SERS) effect are among the most versatile sensors due to their ability to characterize samples in various states of matter. The appeal of the SERS sensors lies in the molecular “fingerprint” specificity, sensitivity, and the non-invasive nature of the analysis. Although the current state of art SERS sensors have advanced toward ultrasensitivity with single-molecule detection limit, ultrafast analysis at femtosecond and sub-nanometer resolution, the application of these innovations in the industrial settings is still limited by the complexity of the substrate fabrication and the reproducibility of the SERS measurements. In this context, a study on the SERS sensors fabrication strategies and reliability of the SERS analysis is essential. This dissertation investigates various hybrids of noble metal and semiconductor materials and surface modifications to improve the stability and reliability of SERS measurement. Different industrial applications, including detection of petrochemical organic compounds and sensitive biochemical samples, were conducted to evaluate the performance of different SERS sensor designs. Evaluation of the morphology and surface functionalization of the substrate was accomplished to optimize the performance and stability of the collected signal. Together with the separately performed studies on Raman signal processing and interpretation, the proposed SERS sensor fabrication and signal analysis approach was successfully applied to detect and quantify organic isomers compounds and mutation point in peptides. The findings presented in this thesis offer rational SERS substrate designs and detection approaches that can advance the future commercialization of SERS sensors.
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Impact des nano-particules sur le comportement au jeune âge et à l’état frais des matériaux à base de ciment / Impact of nano particle on the early age and fresh state behavior of cement based materialsConte, Théau 15 June 2017 (has links)
Ce travail de thèse rentre dans le cadre de la problématique générale, en plein développement actuellement, concernant l’exploitation des nanotechnologies pour le développement d’écomatériaux, dont les propriétés sont significativement améliorées et élargies. A cause de leur surface spécifique particulièrement élevée, l’ajout d’une infime quantité (de l’ordre du % par rapport au ciment) de particules nanométriques à une formulation d’un matériau cimentaire peut entrainer des modifications significatives des propriétés du produit. Ces modifications peuvent intervenir à tout niveau de maturation du matériau en impactant les propriétés correspondantes : état frais (rhéologie), jeune âge (cinétique de prise, retrait, fissuration) et état durci (propriétés mécaniques, thermiques et durabilité).Le principal travail de cette thèse a consisté à étudier l’impact de nano particules isotropes (nano silice) et anisotropes (nano argile) sur la rhéologie des matériaux cimentaires à l’aide d’un nouveau protocole : la rhéologie oscillatoire aux grandes amplitudes. De plus, l’impact de celle-ci sur le processus d’hydratation des matériaux contenant de hauts dosages en laitier de haut fourneaux a aussi été étudié. / This PhD gets in the larger topic of the use of nano-technology to develop eco-friendly materials whose properties are improved. Due to their very high specific surface, a very low quantity (only a few percent) of nano particles into a cement-based material can induce significant changes of materials properties. These changes can take place at every ages of materials such as fresh state (rheology), young age (kinetic of hydration, shrinkage) or long term (mechanical, thermal properties and durability). During this PhD, different types of nano particles are considered: isotropic (nano silica) or anisotropic (nano clay). The main objective is to consider the impact of nano particles on rheological properties considering a new rheological protocol: large amplitude oscillation shear (LAOS). Besides, interaction between nano particles and hydration products in the case of cement based material containing high dosage of slag is also considered. This study will help to understand how nano particles change material properties at fresh state and young age. Indeed, it is at these ages that materials properties are lower when cement is replaced by other material.
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Responsive Materials via Diels-Alder ChemistryStrange, Gregory Alan 01 March 2012 (has links) (PDF)
The corrosion of infrastructure imposes a significant monetary cost, and at times human cost, upon society. Methods to improve corrosion resistance of materials are described herein which utilize the reversibility of the Diels-Alder reaction to impart thermal responsiveness upon materials. Such stimuli responsiveness can potentially play a role in self healing properties which lead to reduced cracking and thus increased corrosion protection.
Reversible Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates. Hydrophobic dieneophiles were prepared and attached to glass slides and capillaries to yield a nonwetting surface. Thermal treatment of the surfaces cleaved the Diels-Alder linkage, and resulted in the fabrication of a hydrophilic surface. Preliminary analysis utilized contact angle (CA) measurements to monitor the change in surface energy, and observed a hydrophilic state (CA - 70±3°) before attachment of the dieneophile to a hydrophobic state (CA - 101±9°) followed by regeneration of the hydrophilic state (CA - 70±6°) upon cleavage of the Diels-Alder linkage. The treatments were then applied to glass capillaries, with effective treatment confirmed by fluid column measurements. Patterned treatments were also demonstrated to provide effective fluid flow gating.
Reversible Diels-Alder linkages were incorporated into polymer thermoset binding resins in order to provide a means by which a crosslinked thermoset could undergo stimuli responsive reversible crosslinking. The binder systems which were utilized included two types of amine curing agents, polydimethylsiloxane (PDMS) and Jeffamine® polyetheramines (PEA), and two types of epoxy resins, EPON resin based on diglycidyl ether of Bisphenol-A and epoxidized soybean oil. Various dienes and dienophiles were employed to functionalize the selected binder systems and were met with various degrees of success. The synthetic technique which proved to be the most promising was the Diels-Alder modification of the epoxidized soybean oil.
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Molecular Shape Amphiphile Based on Keggin Polyoxometalates and iso-Butyl Polyhedral Oligomeric Silsesquioxanes: Synthesis and CharacterizationShan, Wenpeng 17 September 2014 (has links)
No description available.
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Detection of Nano Particles in TEM Images Using an Ensemble Learning AlgorithmLohiya, Paranjith Singh 01 June 2015 (has links)
No description available.
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Synthese intermetallischer Nanostrukturen in KohlenstoffnanoröhrenHaft, Marcel 29 May 2017 (has links) (PDF)
Kohlenstoffnanoröhren als eigenständige Modifikation des Kohlenstoffs sind zylindrische, aus mehreren Lagen Kohlenstoff aufgebaute Röhren, die über einen Hohlraum im Inneren verfügen. Bereits kurze Zeit nach ihrer Entdeckung, kam die Idee auf, Substanzen in diesen Hohlraum zu füllen. Durch den Einbau von Katalysatormaterial während der Synthese, ist bereits eine Vielzahl von Elementen als Füllmaterial zugänglich. Um jedoch nicht auf Elemente limitiert zu sein, die als Katalysator für die CNT-Synthese dienen, ist es möglich eine postsynthetische Füllung durchzuführen. Hier werden ungefüllte CNT geöffnet und anschließend, unter Ausnutzung der Kapillarkräfte, gefüllt.
In der vorliegenden Arbeit wurden zunächst verschiedene Methoden zur Füllung untersucht. Neben lösemittelbasierten Methoden wurde mit Salzschmelzen, durch Gasphasentransport und durch Füllung mit einer kovalenten Präkursorverbindung gefüllt. Da metallische Partikel das Ziel waren, folgte im Anschluss an die Füllung mit Salzen, Salzlösungen, oder anderen Präkursoren jeweils eine Reduktion mit Wasserstoffgas bei erhöhten Temperaturen. Die Ergebnisse der Füllung wurden umfassend mittels Elektronenmikroskopie untersucht. Füllungsgrade wurden mittels Thermogravimetrie bestimmt. So konnten für zahlreiche Elemente eine geeignete Methode zur Füllung mit metallischen Partikeln entwickelt werden.
Im Falle der Füllung mit Zinn konnte zudem gezeigt werden, dass ein Zusammenhang zwischen der Dauer der Füllreaktion und dem Anteil an drahtartigen Nanostrukturen in den CNT, sowie ein Zusammenhang zwischen der eingesetzten Lösungskonzentration und dem Füllungsgrad besteht. Im weiteren Verlauf der Arbeit wurde die Synthese von intermetallischen Partikeln in CNT untersucht. Hierbei dienten die Systeme Nickel-Zinn und Cobalt-Zinn, die als vielversprechende Materialien im Einsatz als Anodenmaterial in Lithium-Ionen-Akkumulatoren diskutiert werden, als Modellsysteme.
Zunächst wurde gezeigt, dass es nicht möglich ist, aus einem Gemisch des Zinnsalzes und des jeweiligen anderen Salzes erfolgreich intermetallische Partikel herzustellen. Mittels Pulverröntgendiffraktometrie (XRD) und energiedispersiver Röntgenspektroskopie (EDX) konnte gezeigt werden, dass lediglich Zinnpartikel in den CNT vorhanden waren.
Schließlich konnte mit dem Verfahren der sequentiellen Füllung eine erfolgreiche Synthese intermetallischer Nanostrukturen bewerkstelligt werden. Hierbei wird die CNT zuerst mit einer Lösung von Zinnchlorid
gefüllt und schließlich reduziert. Anschließend erfolgt eine weitere Füllung mit einem Nickel- bzw. Cobaltsalz und einer nachfolgenden Reduktion. Während dieser zweiten Reduktion erfolgt die Bildung der intermetallischen Nanostrukturen in den CNT. Mittels XRD konnte gezeigt werden, dass tatsächlich intermetallische Strukturen in der Probe enthalten sind und dass man zudem durch das Verhältnis der beiden eingesetzten Elemente (Zinn zu Nickel bzw. Cobalt) Einfluss auf die vorherrschende intermetallische Verbindung nehmen kann. Durch EDX-Linienscans und Elementkarten, die am Transmissionselektronenmikroskop angefertigt wurden, konnte nachgewiesen werden, dass einzelne, in den CNT befindliche Partikel, tatsächlich aus den beiden Elementen Zinn und Nickel bzw. Cobalt bestehen und somit intermetallisch sind.
Ein erster Test des erhaltenen Materials aus CNT und intermetallischen Nickel-ZinnVerbindungen als Anodenmaterial konnte bereits durchgeführt werden. Die gemessene Kapazität lag bereits im Bereich von Graphit, welches üblicherweise als Anodenmaterial verwendet wird, könnte jedoch durch Erhöhung des Anteils der intermetallischen Verbindung noch weiter gesteigert werden.
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On the synthesis, measurement and applications of solar energy materials and devicesKevin, Punarja January 2016 (has links)
Second generation solar cells based on thin film semiconductors emerged as a result of the past ten years of intense research in the thin film preparation technology. Thin film solar cell technology can be cost effective as it uses comparatively cheap materials suitable for solar building integration. Chemical Vapour Deposition (CVD) is a well-known method for the deposition of high quality thin films. This thesis describes the synthesis of novel tin(II)dithiocarbamate [Sn(S2CNEt2)2] and bis(diphenylphosphinediselenoato) tin(II) [Sn(Ph2PSe2)2] and these complexes as single source precursor for the deposition of SnS and SnSe and by using the combination of [Sn(Ph2PSe2)2] with [Cu(acac)2], Cu2SnSe3 thin films were deposited by AACVD. By using suitable combinations of metal complexes ([nBu2Sn(S2CNEt2)2], [Cu(S2CNEt2)2] [Zn(S2CNEt2)2] [Zn(Se2CNEt2)2] [Zn(acac)2], [Sn(OAc)4], [Cu(PPh3){Ph2P(Se)NP(Se)Ph2}] thin films and nanocomposites of CZTS, CFTS, CZTSe, CFTSe, CZFTS, , CZFTSe, CZTSSE, CFTSSe and CZFTSSe were prepared. The effect of precursor concentration and deposition temperature on the structure, morphology and composition of the thin films were studied in detail using by powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and elemental mapping. This thesis addressing the structural inhomogeneity, control of growth and material characterization is expected to yield closer performance parity between CZTS-Se and CIGS solar cells. A series of systematic experiments were carried out. Through AACVD and simple solvothermal methods CZFTS nanoparticles and thin films were prepared. The simple, potentially, low-cost nature of the CZTS nanoparticles and the enhancement of charge carrier mobility achieved suggest that these nanoparticles have potential in the improvement of OFETs and perhaps other organic electronic devices.
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Synthesis of gold nano-particles in a microfluidic platform for water quality monitoring applicationsDatta, Sayak 15 May 2009 (has links)
A microfluidic lab-on-a-chip (LOC) device for in-situ synthesis of gold nano-particles
was developed. The long term goal is to develop a portable hand-held diagnostic
platform for monitoring water quality (e.g., detecting metal ion pollutants).
The LOC consists of micro-chambers housing different reagents and samples that feed to
a common reaction chamber. The reaction products are delivered to several waste
chambers in a pre-defined sequence to enable reagents/ samples to flow into and out of
the reaction chamber. Passive flow actuation is obtained by capillary driven flow
(wicking) and dissolvable microstructures called ‘salt pillars’. The LOC does not require
any external power source for actuation and the passive microvalves enable flow
actuation at predefined intervals. The LOC and the dissolvable microstructures are
fabricated using a combination of photolithography and soft lithography techniques.
Experiments were conducted to demonstrate the variation in the valve actuation time
with respect to valve position and geometric parameters. Subsequently, analytical models were developed using one dimensional linear diffusion theory. The analytical
models were in good agreement with the experimental data. The microvalves were
developed using various salts: polyethylene glycol, sodium chloride and sodium acetate.
Synthesized in-situ in our experiments, gold nano-particles exhibit specific colorimetric
and optical properties due to the surface plasmon resonance effect. These stabilized
mono-disperse gold nano-particles can be coated with bio-molecular recognition motifs
on their surfaces. A colorimetric peptide assay was thus developed using the intrinsic
property of noble metal nano-particles. The LOC device was further developed on a
paper microfluidics platform. This platform was tested successfully for synthesis of gold
nano-particles using a peptide assay and using passive salt-bridge microvalves.
This study proves the feasibility of a LOC device that utilizes peptide assay for
synthesis of gold nano-particles in-situ. It could be highly significant in a simple
portable water quality monitoring platform.
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Dissipative Particle Dynamics Simulations Study on Organic Thiol Molecule-Au Nano-particles Aggregation and Protein Folding in Aqueous SolutionJuan, Shen-ching-chi 19 July 2005 (has links)
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