Organic acids are usually the reactants which proceed in chlorination reaction into products of disinfection by-products in water treatment plant. The purpose of this study is by using tests of kinetics and equilibrium adsorptions to investigate adsorption characteristics and kinetic model evaluations of selected organic acid in solution. We use commercial carbon nano-tube for the adsorbents. The major factors in adsorption tests include the concentration of fulvic acid (a typical organic acid in raw water), pH, ionic strength and temperature. Experiment results exhibited kinetic adsorption reached equilibrium about 120 minutes, the adsorption capacity increased with concentrations increasing of fulvic acid and decreased with ionic strengths. The best selection in kinetic models evaluation, fitting models such as Modified Freundlich equation, Pseudo-1st-order equation and Pesudo-2nd-oder equation is Modified Freundlch equation model. In addition, intraparticle diffusion equation model was fitted well and showed adsorption process was controlled with pore diffusion. The maximum adsorption capacity varied from 26.094 to 20.772 mg/g when temperature ranging from 4 to 45¢J. Isotherm adsorption results were fitted on Langmuir and Freundich models. The £GG¢X values ranged from -0.930 to -1.014 kcal/mol, £GH¢X:-1.561 kcal/mol and £GS¢X:-2.02 cal/mol. Thermodynamic parameters indicated that the adsorption is spontaneously and an exothermic reaction. Adsorption of fulvic acid by carbon nano-tube has a good performance when operation conditions of higher fulvic acid concentration, lower ionic strength, lower pH and lower temperature.

The mechanical and electrical properties of thin films have been become important and urgent in recent years, especially, the laminated structure made by films stacked over hundreds of layers. For example, the Multi-Layered Ceramic Capacitors (MLCCs) are such structures fabricated by one layer ceramic film interleaves with one layer electrode film repeatedly a hundred times. Thus, the advantages of MLCCs include small volume, mass product, and high capacity. That makes the MLCCs the necessary part of passive components. The Finite element method is adopted in the study. The model is built by the simulation program of ANSYS. After meshing and setting boundary conditions, the numerical process is performed. The numerical simulation was started first by applying a uniformly distributed pressure on the top of near hundred layers of MLCCs before sintering process with the bottom plate fixed. Then, the displacement and stress fields of MLCCs under five pressures were obtained and discussed. In order to visualize the results, the data of displacement and the stress fields were listed in Tables and plot in Figures. In addition to the MLCCs under vertically and uniformly distributed pressure, the slightly slant distributed pressure and gradient distributed pressure had been simulated. Next, the results of changing Young¡¦s modulus had also been received. It is found that the vertical distributed pressure and slant distributed pressure were not the main factor led to the side deformation. The lateral constraint of gradient distributed pressure would influence the deformation of the MLCCs significantly.

Fully conjugated heterocyclic aromatic rod-like polymer poly-p-phenylene- benzobisoxazole (PBO) and coil-like poly-(3-hexylthiophene) (P3HT) were applied as opto-electronically active layer. The two polymers mixed with nano-carbon particles, having excellent optical absorption and electric conductivity, of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) or esterified multi-wall carbon nano-tube (MWNT-COOC10H21) as well as a hole transporting layer of PEDOT:PSS. Photovoltaic (PV) cells of indium-tin-oxide (ITO)/PEDOT:PSS/nano-carbon particle:fully conjugated polymer/Al were fabricated for optical and electrical characterizations. Tri-layered structure of ITO/PEDOT:PSS/PBO/PCBM/Al produced a straight current-voltage relation showing no PV effects. Upon changing the active layer into PCBM doped P3HT layer (PCBM:P3HT), it produced good PV effects suggesting that the doped layer had a penetrating network to facilitate the PV effects. When PCBM or MWNT-COOC10H21 was doped into P3HT, the device PV effects were increased significantly with nano-carbon particle concentration. The direct-current electric conductivity parallel to the film surface (£m¡ü)was increased with the nano-carbon particle concentration. By changing the thickness of hole transporting PEDOT:PSS and of opto-electronically active layers, it was found that when the PEDOT:PSS layer was decreased from 90 nm to 32 nm, there was a slight increase of PV cell efficiency. The active layer of PCBM:P3HT with a thickness of 99 nm had the best optical absorption and charge transport leading to an increase of PV cell efficiency.

Solar cells are at the frontier of renewable energy technologies. Photovoltaic energy is clean, reusable, can be used anywhere in our solar system and can be very well integrated with power distribution grids and advanced technological systems. Thin film solar cells are a class of solar cells that offer low material cost, efficient fabrication process and compatibility with advanced electronics. However, as of now, the conversion efficiency of thin film solar cells is inferior to that of thick crystalline cells. Research efforts to improve the performance bottlenecks of thin film solar cells are highly motivated. A class of techniques towards this goal is called light trapping methods, which aims at improving the spectral absorptivity of a thin film cell by using surface texturing. The precise mathematical and physical characterization of these techniques is very challenging. This dissertation proposes a numerical and computational framework to optimize, design, and fabricate efficient light trapping structures in thin film solar cells, as well as methods to verify the fabricated designs. The numerical framework is based on the important "inverse optimization" technique, which is very is widely applicable to engineering design problems. An overview of the state-of-the-art thin film technology and light trapping techniques is presented in this thesis. The inverse problem is described in details with numerous examples in engineering applications, and is then applied to light trapping optimization. The proposed designs are studied for sensitivity analysis and fabrication error, as other aspects of the proposed computational framework. At the end, reports of fabrication, measurement and verification of some of the proposed designs are presented. / text

This thesis describes novel microel ectromechanical system (MEMS) based electrochemical gas sensors and methods of fabrication. This thesis presents the research in two parts. In the first part, a method to handle a thin silicon wafer using an electrochemically active adhesive is described. Handling of a thin silicon wafer is an important issue in 3D-IC manufacturing where through silicon vias (TSVs) is an enabling technology. Thin silicon wafers are flexible and fragile, therefore difficult to handle. In addressing the need for a reliable solution, a method based on an electrochemically active adhesive was developed. In this method, an electrochemically active adhesive was diluted and spin coated on a 100 mm diameter silicon wafer (carrier wafer) on which another silicon wafer (device wafer) was bonded. Device wafer was subjected to post processing fabrication technique such as wafer thinning. Successful debonding of the device wafer was achieved by applying a voltage between the two wafers. In another part of the research, a fabrication process for developing a functional nanoporous material using atomic layer deposition is presented. In order to realize a nanoporous electrode, a nanoporous anodized aluminum oxide (AAO) substrate was used, which was functionalized with very thin layers (~ 10 nm) of platinum (Pt) and aluminum oxide (Al2O3) using atomic layer deposition. Nanoporous material when used as an electrode delivers high sensitivity due to the inherent high surface area and is potentially applicable in fuel cells and in electrochemical sensing. The second part of the thesis addresses the need for a high performance gas sensor that is applicable for asthma monitoring. Asthma is a disease related to the inflammation in the airways of the lungs and is characterized by the presence of nitric oxide gas in the exhaled breath. The gas concentration of above approximately 50 parts-per-billion indicates a likely presence of asthma. A MEMS based electrochemical gas sensor was successfully designed and developed to meet the stringent requirements needed for asthma detection. Furthermore, to enable a hand held asthma measuring instrument, a miniaturized sensor with integrated electrodes and liquid electrolyte was developed. The electrodes were assembled at a wafer-level to demonstrate the feasibility towards a high volume fabrication of the gas sensors. In addition, the designed amperometric gas sensor was successfully tested for hydrogen sulphide concentration, which is a bio marker for bad breath. / <p>QC 20150907</p>

The modification of spontaneous emission, i.e. the Purcell effect, with optical cavities has been highly studied over the past 20 years as one of the most important goals for cavity quantum electrodynamics (cQED). The recent development of using surface plasmon resonances to concentrate optical field into sub-wavelength scale further extended cQED research of into a new regime. However, although metallic reflectors are used in some of the earliest demonstrations of cQED, the use of metals is not preferable in high Q optical cavities due to the lossy nature of metals. The presence of metals near an optical emitter also strongly alters its radiation dynamics. As a result, the development of plasmonic cavities brings not only new opportunities but also new problems and challenges. In this thesis we describe four different plasmonic cavity designs along with optical simulations and measurements on them to demonstrate: large spontaneous emission enhancement, controlled mode tuning, and control of the plasmonic band-gap and resonances of high-Q plasmonic cavities for coupling to specific emitters. We hope that our work can guide and inspire researchers who are moving from traditional cavity designs to novel plasmonic devices, helping them to establish design concepts, fabrication criteria, and baselines for characterizing these devices. / Engineering and Applied Sciences

Nano-structures, such as photonic crystal cavities and metallic antennas, allow one to focus and store optical energy into very small volumes, greatly increasing light-matter interactions. These structures produce resonances which are typically characterized by how well they confine energy both temporally (quality factor–Q) and spatially (mode volume–V). In order to observe non-linear effects, modified spontaneous emission (e.g. Purcell enhancement), or quantum effects (e.g. vacuum Rabi splitting), one needs to maximize the ratio of Q/V while also maximizing the coupling between the resonance and the active medium. In this dissertation I will discuss several projects related by the goal of controlling light-matter interactions using such nano-structures. In the first portion of this dissertation I will discuss the deterministic placement of self-assembled InAs quantum dots, which would allow one to precisely position an optically-active material, for maximum interaction, inside of a photonic crystal cavity. Additionally, I will discuss the use of atomic layer deposition to tune and improve both the resonance wavelength and quality factor of silicon based photonic crystal cavities. Moving from dielectric materials to metals allows one to achieve mode-volumes well below the diffraction limit. The quality factor of these resonators is severely limited by Ohmic loss in the metal; however, the small mode-volume still allows for greatly enhanced light-matter interaction. In the second portion of this dissertation I will investigate the coupling between an array of metallic resonators (antennas) and a nearby semiconductor quantum well. Using time-resolved pump-probe measurements I study the properties of the coupled system and compare the results to a model which allows one to quantitatively compare various antenna geometries.

No description available.

Patterned arrays of metallic nanostructures are commonly used in photonics, electronics, as well as functional materials and biotechnology because of their unique electronic and optical properties. Although great effort has been devoted to the development of nano-patterning techniques in the past decades, there are still existing challenges for nano-fabrication to achieve fine resolution and complex features over macroscopic areas in a reasonable time period. Herein, we devise two versatile patterning strategies, namely indentation colloidal lithography (ICL) and oblique colloidal lithography (OCL), for the stepwise patterning of planar substrates with numerous complex and unique designs. Those strategies combine colloidal self-assembly, imprint molding in conjunction with capillary force lithography and reactive ion etching, all of which are simple and straightforward. Hexagonal arrays of symmetric and nonconcentric gold features are fabricated on glass substrates with highly controllable geometric parameters. The width, size and asymmetry of each surface structure could be tuned down to the ~10 nm level while the scale of the patterned area could exceed 1 cm^(2). Moreover, our technique also leads to the ability to develop an enormous variety of patterns through stepwise amplification of feature types. In particular, some of the features are fabricated for the first time, including target-triangle, hexagram, hexagram-dot and triangle-dot. Distinctive surface plasmon resonance (SPR) properties, such as higher order surface plasmon modes and Fano resonances are both observed from our patterns, which would be highly desired forthe study of plasmonic coupling. In addition, we have demonstrated a surface orientation dependent Raman selectivity on two nano-structures for the first time. Molecular vibrations with opposite symmetries can be selectively enhanced on different substrates. As a demonstration, this property is applied to the odd-even effect of n-alkanethiol self-assembly monolayers (SAMs) on the gold surface. The alternative alternation of the intensity ratios of two vibration pairs have been shown by surface enhanced Raman spectroscopy (SERS) as a function of the number of carbon atoms. The results obtained exhibit high sensitivity and excellent agreement with previous publications.

Electrospray ionization (ESI) has been an invaluable technique to mass spectrometry (MS) especially for analyzing large bio-molecules with unparalleled sensitivity, robustness, and simplicity. Great effort in the development of ESI technique has been devoted in the emitter design, as its shape and geometry have proved pivotal to the electrospray performance and further MS detection. Intrinsic problems for the traditional single-hole emitters including clogging and low throughput limit the applicability of the technique. To address this issue, the current project is focused on developing multiple electrospray (MES) emitters for improved ESI-MS analysis. In this thesis, joint work of both computational fluid dynamic (CFD) simulations for electrospray and offline electrospray experiments for spray current measurement were performed. Numerical simulations were used to test the effect of various emitter designs on electrospray performance and the laboratory results serve as a guide and validation. The CFD code was based on Taylor-Melcher leaky dielectric model (LDM) and the transient electrospray process was successfully simulated. The method was first validated via a 750 μm inner diameter (i.d.) emitter and further applied to a 20 μm i.d. model. Different stages of the electrospray process were visually demonstrated and the quantitative investigations for the change of spray current under various applied electric fields and flow rates share good agreement with previous simulations and measurements. Based on the single-aperture prototype, MES simulations were performed with 2-hole and 3-hole emitters. Simulation predictions compared favorably with the experimental results. Evidence from this work has proved that CFD simulation can be used as an effective numerical tool to test emitter designs for MES. The benchmarking result on the successful simulation of a microscale emitter electrospray achieved in this work is believed to be the smallest scale of the dynamic simulation for electrospray published to date. / Thesis (Master, Chemistry) -- Queen's University, 2011-12-23 13:36:08.754