Polymer brushes represent a relatively new class of materials and are referred to an assembly of polymer chains tethered by one of their extremities to a surface by a chemical bond. Different techniques to produce polymer brushes exist but our privileged choice was about the ¡§grafting from¡¨ method due to the better control over the types of grafted polymer, the surface-grafting density, and the chain-lengths. In our project, we focused on polymerizations from self-assembled monolayers of thiol chemisorbed on gold surface, bearing end-group functions as anchoring sites. The main objective of this work is to develop multifunctional polymeric surfaces composed by micro-domains of diverse compounds, which contain opposite features. Poly(ƓÕ-caprolactone) and poly(L,L-lactide)-based brushes both known for their high degree of crystallinity and hydrophobicity, and poly(dimethylamino ethyl methacrylate) (PDMAEMA)-based brushes for their hydrophilicity and external stimuli responsive characteristics were investigated. Moreover, the design of these advanced materials can be achieved with patterning technique such as micro-contact printing, leading to a spatial confinement of the polymer brushes. In order to reach our objective, the thesis was decomposed in different parts. First, the preparation of homogeneous and heterogeneous monolayers derived from thiols on gold surface will be investigated. Secondly, the ¡§grafting from¡¨ synthesis of homo-polymers from thiol end group will be carried out. This part required the development of synthesis conditions for both types of homopolymer brushes. Subsequently, these parameters were applied to the creation of a binary system by the growth of two different macromolecular chains on the same substrate. Finally, upon the ¡§smart¡¨ behavior of PDMAEMA, the potential of the polymer as chemical sensor was evaluated with single walled and multi walled-carbon nanotubes (SW- and MW-CNTs) as interesting conductive (nano)fillers.

Amorphous selenium based digital radiography has attracted much attention because of selenium's high X-ray absorption and excellent charge transport properties, and the ability to be created thick (typically 100 to 1000 micron) uniform layers over a large area (typically 30 cm X 30 cm) at low processing temperatures (typically at around 50 degree C substrate temperature). In this work, the excess noise in amorphous selenium has been studied. A number of device parameters were altered to study the noise characteristics, such as the metal of the electrodes, bulk material composition, device volume, surface conditions and substrate temperature. All the samples had a transverse geometry with 20 to 200- micron thick layers of amorphous selenium electroded with metal at the top and at the bottom. Sample devices were fabricated by conventional vacuum deposition.<p> Noise power was measured over a limited bandwidth of 1 kHz. The fluctuations for one sample amounted to 1% of the bias current. The excess noise was mainly 1/<i>f</i> noise with the slope ranging from -0.77 to -1.4. Interpretation of the noise spectra was complicated due to the samples' highly non-linear I-V relation and long time transients.<p> The metals of the electrode clearly showed a large effect on both the magnitude and shape of the noise spectrum. Of the metals studied, aluminum produced the least normalized noise and platinum the most. The addition of arsenic caused a decrease in the normalized noise. An additional 0.2% (% wt.) arsenic decreased the 1/<i>f</i> noise magnitude by more than a decade, but did not change the slope. The addition of chlorine did not affect the noise magnitude. Amorphous selenium is quite vulnerable to stress and in particular, external mechanical stress causes crystallization. The surface of the sample was gently abraded, applying the least possible amount of stress to the selenium layer. A change in the surface condition before the top electrode was deposited showed that a roughened surface decreased the noise magnitude substantially. These results strongly indicate that the noise is controlled by the metal-semiconductor interface.<p> Noise characteristics in multilayered samples were examined. The p-i-n and n-i-p structures consisted of 200 micron i-layer with 2 to 6 micron p- and n-like layers. The noise fluctuation in the current are typical of 1/<i>f</i> noise showing a power-law spectrum with slopes between -0.9 to -1.1. These samples showed a substantial decrease in the noise power compared to single layer samples; the additional n-like and p-like layers acted as carrier sources so that the current was not controlled by the metal interface. Hence, the measurements are closer to the intrinsic noise of a-Se. After exposure to 14 R (Roentgen) of X-rays, the normalized noise decreased by a factor of 1.6 for the n-i-p structure.

Electrical conductive adhesives (ECAs) containing silver filler and polyaniline co-filler were characterized for their electro-mechanical properties. Polyaniline is a conductive polymer and has a moderate conductivity in between those of the silver and epoxy. Incorporation of polyaniline (μm sized) in silver-epoxy facilitated the electrical conduction in ECAs and reduced the percolation threshold- a minimum volume of filler necessary to initiate the conduction. It also prevented the localization of charge carriers due to aggregation of silver filler particles. ‘Bridging effect’ was observed due to addition polyaniline in which the polyaniline enhanced the tunneling of electrons over the silver filler particles. We have investigated the polyaniline co-fillers as a promising alternative way to tune the mechanical and electrical properties of the ECAs and have provided a detailed analysis of the electro-mechanical properties of silver-epoxy (Ag-epoxy) and silver-polyaniline-epoxy (Ag-PANI-epoxy) system in both partially-cured/ viscoelastic and fully-cured states. Analysis of electro-mechanical properties of silver-epoxy and silver-polyaniline-epoxy also provided the insights into electrical contact resistance of ECAs under compressive force. Electro-mechanical properties of ECAs were measured ‘in-situ’ using micro-indentation technique. We also synthesized the electrically conductive and highly crystalline nanotubes of polyaniline by mini-emulsion polymerization of aniline. The motivation behind the synthesis of polyaniline was to propose a potential filler/co-filler for replacement of metallic filler in ECAs. Electrical conductivity of polyaniline nanotubes was tuned by in-situ doping using hydrochloric acid as a dopant. Increase in dopant caused the polyaniline crystallite to grow along (400) plane. Optical, structural, electrical and thermal properties of polyaniline nanotubes are reported with varying amount of dopant. We fabricated the flexible electrically conductive coating of polyaniline tubes with uniform dispersion of polyaniline. Electrical performance of as-synthesized flexible coating is also revealed.

A previous study in chickens revealed that myosin light chain kinase (MLCK), f actin, and myosin are found on the crystalline lens. Their polygonal arrangement at the posterior surface resembles a muscle tissue, which suggests that these proteins may have a contractile role in accommodation. The ciliary muscle in chickens is skeletal in nature and, therefore, chickens were used to test the hypothesis that contractile microfilaments play a role in accommodation. Ciliary nerve-induced accommodation was measured in the presence of an MLCK inhibitor 1-(5-Iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7). Eyes of 6-day old white Leghorn chickens (gallus gallus domesticus) were enucleated in Tyrode’s saline solution while keeping the ciliary nerve intact. One eye was treated with ML-7 and the other eye was treated with vehicle only. Three concentrations of ML-7 were used: 1 µM, 10 µM, and 100 µM. Two experiments were carried out, one including a (3×10 min) wash and one without. Focal lengths of the vehicle- and ML-7-treated eyes were measured before, during and after accommodation. Immunoblots were used to detect the amount of phosphorylated myosin with and without the inhibitor. Focal lengths for accommodation were shorter than those at rest (p<0.001). In the wash experiment, vehicle-treated eyes had higher accommodative amplitudes compared to ML-7-treated eyes for all three dosage groups. In the no-wash experiment, only the 1 µM group demonstrated the same trend as the wash experiment. For the 10 µM and 100 µM groups, ML-7-treated eyes had higher accommodative amplitudes compared to vehicle-treated eyes. Immunoblots revealed varying amounts of inhibition within pairs of eyes as well as between birds for both experiments. Results from this experiment indicate that ML-7 was not effective at determining whether contractile microfilaments found on the lens contribute to accommodation.

A previous study in chickens revealed that myosin light chain kinase (MLCK), f actin, and myosin are found on the crystalline lens. Their polygonal arrangement at the posterior surface resembles a muscle tissue, which suggests that these proteins may have a contractile role in accommodation. The ciliary muscle in chickens is skeletal in nature and, therefore, chickens were used to test the hypothesis that contractile microfilaments play a role in accommodation. Ciliary nerve-induced accommodation was measured in the presence of an MLCK inhibitor 1-(5-Iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7). Eyes of 6-day old white Leghorn chickens (gallus gallus domesticus) were enucleated in Tyrode’s saline solution while keeping the ciliary nerve intact. One eye was treated with ML-7 and the other eye was treated with vehicle only. Three concentrations of ML-7 were used: 1 µM, 10 µM, and 100 µM. Two experiments were carried out, one including a (3×10 min) wash and one without. Focal lengths of the vehicle- and ML-7-treated eyes were measured before, during and after accommodation. Immunoblots were used to detect the amount of phosphorylated myosin with and without the inhibitor. Focal lengths for accommodation were shorter than those at rest (p<0.001). In the wash experiment, vehicle-treated eyes had higher accommodative amplitudes compared to ML-7-treated eyes for all three dosage groups. In the no-wash experiment, only the 1 µM group demonstrated the same trend as the wash experiment. For the 10 µM and 100 µM groups, ML-7-treated eyes had higher accommodative amplitudes compared to vehicle-treated eyes. Immunoblots revealed varying amounts of inhibition within pairs of eyes as well as between birds for both experiments. Results from this experiment indicate that ML-7 was not effective at determining whether contractile microfilaments found on the lens contribute to accommodation.

Amorphous selenium based digital radiography has attracted much attention because of selenium's high X-ray absorption and excellent charge transport properties, and the ability to be created thick (typically 100 to 1000 micron) uniform layers over a large area (typically 30 cm X 30 cm) at low processing temperatures (typically at around 50 degree C substrate temperature). In this work, the excess noise in amorphous selenium has been studied. A number of device parameters were altered to study the noise characteristics, such as the metal of the electrodes, bulk material composition, device volume, surface conditions and substrate temperature. All the samples had a transverse geometry with 20 to 200- micron thick layers of amorphous selenium electroded with metal at the top and at the bottom. Sample devices were fabricated by conventional vacuum deposition.<p> Noise power was measured over a limited bandwidth of 1 kHz. The fluctuations for one sample amounted to 1% of the bias current. The excess noise was mainly 1/<i>f</i> noise with the slope ranging from -0.77 to -1.4. Interpretation of the noise spectra was complicated due to the samples' highly non-linear I-V relation and long time transients.<p> The metals of the electrode clearly showed a large effect on both the magnitude and shape of the noise spectrum. Of the metals studied, aluminum produced the least normalized noise and platinum the most. The addition of arsenic caused a decrease in the normalized noise. An additional 0.2% (% wt.) arsenic decreased the 1/<i>f</i> noise magnitude by more than a decade, but did not change the slope. The addition of chlorine did not affect the noise magnitude. Amorphous selenium is quite vulnerable to stress and in particular, external mechanical stress causes crystallization. The surface of the sample was gently abraded, applying the least possible amount of stress to the selenium layer. A change in the surface condition before the top electrode was deposited showed that a roughened surface decreased the noise magnitude substantially. These results strongly indicate that the noise is controlled by the metal-semiconductor interface.<p> Noise characteristics in multilayered samples were examined. The p-i-n and n-i-p structures consisted of 200 micron i-layer with 2 to 6 micron p- and n-like layers. The noise fluctuation in the current are typical of 1/<i>f</i> noise showing a power-law spectrum with slopes between -0.9 to -1.1. These samples showed a substantial decrease in the noise power compared to single layer samples; the additional n-like and p-like layers acted as carrier sources so that the current was not controlled by the metal interface. Hence, the measurements are closer to the intrinsic noise of a-Se. After exposure to 14 R (Roentgen) of X-rays, the normalized noise decreased by a factor of 1.6 for the n-i-p structure.

The objective of the proposed research is to develop novel, fully-packaged voltage controlled oscillators (VCOs), concurrent oscillators, and multi-mode filters using Liquid Crystalline Polymer (LCP) dielectric material that are directly applicable to simultaneous multi-band radio communication. Integrated wireless devices of the near-future will serve more diverse range of applications (computing, voice/video/data communication) and hence, will require more functionality. This research is focused on providing cost-effective and area-efficient solutions for multi-band/multi-mode oscillators and filters using system-on-package (SOP) design methodology. Silicon-based integrated circuits (ICs) provide an economical method of miniaturizing modules and hence, are attractive for multi-band applications. However, fully monolithic solutions are limited, by its high substrate losses, and marginal quality factors (Qs) of the passives, to low profile applications. Furthermore, the VCOs made on conventional packaging technologies are not very cost-effective. This thesis is directed towards developing highly optimized VCOs and filters using LCP substrate for use in multi-mode radio systems. The thesis investigates and characterizes lumped passive components on new LCP based technology feasible for VCO and filter design. The dissertation then investigates design techniques for optimizing both power consumption and the phase noise of the VCOs to be employed in commercial wireless systems. This work then investigates the temperature performance of LCP-based VCOs satisfying military standards. Another aspect of the thesis is the development of dual-band (multi-mode) oscillators. The approach is to employ existing multi-band theories to demonstrate one of the first prototypes of the oscillator. Finally, the design of multi-mode, lumped-element type filters was investigated.

With the aim to enhance the efficiency of utilization of crystalline methionine supplemented in the high plant-protein diet for grouper (Epinephelus coioides), this study used Bacillus subtitlis spore as a probiotic additive in the diet to shorten the absorption time difference between protein-bound amino acid and crystalline methionine. The study was conducted in two parts. In the first part, juvenile groupers were fed for 14 weeks with 5 experimental diets: fish meal diet, high plant-protein diet with/without crystalline methionine, as well as with/without B. subtitlis spore separately. Growth performance, PER, protein digestibility, amino acid digestibility, non-specific immune responses, and free amino acid concentration in both muscle and serum were assessed. The second part was a time-series study on serum free amino acids concentration after a force-feeding experiment. The results showed that crystalline methionine supplementation in the high plant-protein diet effectively improved the growth of E. coioides (P<0.05). However, B. subtitlis spore supplementation did not affect fish growth performance significantly (P>0.05). A delay in the appearance of peak serum amino acid concentration was observed when fishmeal was partially replaced by soy protein. On the other hand, the force-feeding experiment showed that serum essential amino acid (include methionine) concentrations droped drastically after they reached the peak concentrations from being forced-fed with the B. subtilis containing diet. Supplementation of crystalline methionine seemed to ease the drop of serum methionine concentration. Based on these results, it is concluded that addition of B. subtitlis spore in high plant-protein diet for the grouper does not enhance the utilization of crystalline methionine, but supplementation of crystalline methionine significantly improve the growth performance of the grouper.

The present study was undertaken to evaluate the effects of stress on crystalline style characteristics in bivalves of Crassostrea angulata, Meretrix lusoria, and Perna viridis. Firstly, the crystalline style morphological characteristics in normal submerged condition was examined. The presence percentage of crystalline styles in C. angulata collected from different months ranged from 0 to 73%. While, it was 100% in M. lusoria and P. viridis. Secondly, the crystalline style morphological characteristics were investigated under stresses of starvation, hypoxia and desiccation. In C. angulata, the crystalline styles were absent after treated with each of the unfavorable conditions for 1 hour. In M. lusoria, under starvation and hypoxia conditions for 72 hours, the presence percentage of crystalline styles was significantly decreased. Even more, the presence percentages of crystalline styles in M. lusoria reduced to 22% when treated with desiccation for 2 hours. In P. viridis, the presence percentage of crystalline styles was 100% under starvation and hypoxia for 72 hours. In contrast, the mussels were totally dead under desiccation for 72 hours. By comparison, desiccation had greater influence on the three bivalves than starvation and hypoxia based on the standardized crystalline style wet weight (crystalline style wet weight/ shell length). Additionally, the presence percentage of crystalline styles in C. angulata was also influence by fed. In all, among the three examined species, oyster C. angulata is the most sensitive one to unfavorable conditions.

Acryloyloxybenzoic acid (ABA) was prepared by the condensation reaction of acryloyl chloride with p-hydroxybenzoic acid in alkaline medium. The polymerization and grafting of ABA onto Polypropylene were anticipated to occur simultaneously in melt mixing at high temperature. The monomer showed liquid crystalline property. For a better dispersion of ABA in PP before graft copolymerization, a masterbatch of 50-50 (by weight) low density polyethylene + ABA was prepared, which was then used for 5, 10, 15 % ABA + PP mixtures in the Brabender Plasti Corder. Furthermore, these compositions were reprocessed at the same temperature in the molten state. Compression molding was used to prepare films for characterization experiments at 200 &ordm / C under 15000 psi for approximately 3-5 minutes. The graft copolymers were characterized by several techniques / DSC, FTIR, MFI, SEM and mechanical testing. In DSC thermograms the crystallization of PP was seen at approximately 160&ordm / C. An endothermic peak was also assigned to grafted PABA at 280&ordm / C . The incorporation of ABA onto the PP backbone as a graft copolymer (PABA-g-PP) at low percentages results in a possible rearrangement, where tensile strength values increased, while strain decreased. The grafting goes through thermal radicalic mechanism. MFI values were found to increase from 8.7 to 16.35 g/10 min at 10 wt % ABA, then decreased to 10.57 g/10 min at 15 wt % ABA. It is most likely that the presence of PABA produced easy orientational flow up to 10 % of ABA, but at 15 % ABA addition caused a slight decrease in MFI. The tensile test specimens were analyzed by Scanning Electron Microscope. None of the three samples exhibited phase separation. This observation confirms that the graft copolymerization occurrs in a homogenous manner onto PP. The brittle nature of material is observed at all three compositions.