High Internal Phase Emulsion As A Reaction Medium For Fabrication Of Brushite Crystal

This present work was aimed at fabrication of porous brushite crystals using oil-in-water high internal phase emulsion stabilized by synthesized palm-based nonionic surfactant as a reaction medium. This research work was divided into four categories. The first part of the work involved synthesizing palm-based nonionic surfactants. Palm oil derivatives, lauryl, palmityl and stearyl alcohols as renewable resources, were ethoxylated with an average of three, six (or eight or nine) and 100 moles of ethylene oxide. The critical micelle concentration of the synthesized surfactants was found to decrease with increasing ethylene oxide head groups due to intertwist amongst the head groups. This phenomenon enhances surfactant-surfactant interaction rather than surfactant-solvent interaction which increases the rate of micellization as proven by the Gibbs energy. The increase in the surfactant tail length had minimal effect on micellization. The second part of the work was to stabilize the high internal phase emulsion using the synthesized surfactants. The oil phase was vegetable oil, namely olive and olein oils. These UPLOAD emulsions, with dispersed phase of more than 75 wt%, were easily prepared by one-pot homogenization. Due to the high oil volume fraction, the oil droplets were no longer spherical but were squeezed to take the shape of polyhedral. Light scattering results showed that the droplet size increased with increasing ethylene oxide chain length. The rheology of the emulsions was governed by droplet size and oil volume fraction. The emulsions exhibited high stability as indicated by the rheological measurements even after storage at 40oC for three months. The third part of the work was on the fabrication of brushite crystals with high degree of porosity using the high internal phase emulsion as a reaction medium. The porosity of the crystals was manifested by precursor concentration, surfactant concentration, oil volume fraction, mixing method, mixing time, aging temperature, precursor type, mode of recovery and surfactant head group. Pore size of the brushite crystals was less than 5 μm. The mechanism for the formation of porous brushite crystals was postulated schematically based on the small angle x-ray scattering analysis. The fourth and final part of this work was related to the application of the porous brushite crystals as drug delivery devices. Prior to the controlled release study, the crystals were subjected to cytotoxicity test to ensure their compatibility with synoviocytes, which are cells that line the knee joints of rabbits. The crystals were found to enable cell growth for up to five days. Sodium ampicillin, a wide spectrum antibiotic, was successfully loaded into the pores of the crystals and subsequently released in vitro for 14 days. This work underlines the simplicity of using highly stable high internal phase emulsion as a reaction medium for the fabrication of porous brushite crystals, in which when loaded with drug, exhibited potential as localized bone treatment demonstrated by the promising controlled release rate

Analogical Learner For Natural Language Processing Based On Structured String-tree Correspondence (sstc) And Case-based Reasoning

Mesin terjemahan melalui contoh menggunakan contoh penterjemahan yang seiras yang didapati daripada bank pengetahuan dua bahasa (BKB). Example-Based Machine Translation (EBMT) is using the similar translation examples which are retrieved from the Bilingual Knowledge Bank (BKB) to translate an input sentence

Application Of Quantitative Pharmacological Modeling To Improve Drug Therapy In Older Adults

University of Minnesota Ph.D. dissertation. 2016. Major: Experimental & Clinical Pharmacology. Advisor: Angela Birnbaum. 1 computer file (PDF); 165 pages.Consideration of the elderly as a special population in pharmacological treatment is often overlooked. The consequence of this is an increased likelihood of therapeutic failure or adverse drug effects in elderly patients. Particularly given the huge disease burden and challenges with clinical trial recruitment in this population, the development and utilization of approaches that allow better understanding of pharmacological differences in older patients is important. This dissertation aimed to use model-based approaches to examine and characterize age-related differences in the drug disposition and tolerability of topiramate and gabapentin, two neurology drugs commonly used in elderly patients. In alignment with the support for model-based drug development in the elderly population, a modeling and simulation tool that helps facilitate the workflow of pharmacometrics tasks was also developed, as part of this dissertation. Based on data pooled from three randomized, crossover studies in healthy subjects, we characterized the relationship between topiramate plasma concentration and cognitive impairment, as measured by the Symbol Digit Modality Test (SDMT) using population pharmacokinetic-pharmacodynamic modeling. In this analysis, both age and number of prior test administered were important determinants of the baseline SDMT score, with an estimated decrease of 1.13% in baseline SDMT score per year increase in age, and 7% improvement in test scores after two prior testing. Differences in sensitivity to cognitive effect of topiramate based on age, could not be discerned. In the population pharmacokinetic analysis of gabapentin, data comprising of a wide range of renal function and ages from patients (aged 18 years and above) was pooled and the effects of factors such as renal function, age, dose, total daily dose etc. on pharmacokinetic parameters examined, with the objective of providing more information for dosing recommendations, especially in elderly. This data was sufficiently described by a one-compartment pharmacokinetic model, with saturable absorption of gabapentin characterized through a nonlinear function of dose on the extent of absorption. Similar to earlier reports, gabapentin clearance was dependent on renal function in this analysis, and there was no additional effect of age on clearance after this has been accounted for in the model. In addition, no pharmacokinetic differences between nursing home and community dwelling elderly were found, and no improvement in the model fit was observed with inclusion of age as a covariate on other parameters. Hence, from this analysis, no adjustment of dose by age in adults appears to be warranted. Lastly, we developed the R package, Phxnlme, as an auxiliary tool to address existing limitations in the population pharmacokinetic/pharmacodynamics software, Phoenix NLME. With the development and sharing of this R package on a public repository, additional ease is now provided for checking of model assumptions and exploring relationships in the output through graphical visualization. Furthermore, users will also be able to multi-task modeling activities using Phoenix NLME through the use of this R package. This is a functionality that was not readily available with the use of Phoenix NLME as a desktop software. Through this R package release, we hope to facilitate use of model-based drug development, particularly in the elderly population. In line with this, video demonstrations for use of the R package was made and a manual for its use is provided

Enhanced photovoltaic performance of silver@titania plasmonic photoanode in dye-sensitized solar cells

In the present investigation, silver@titania (Ag@TiO2) plasmonic nanocomposite materials with different Ag content were prepared using a simple one-step chemical reduction method and used as a photoanode in high-performance dye-sensitized solar cells. Transmission electron microscopic images revealed the uniform distribution of ultra-small Ag nanoparticles with a particle size range of 2–4 nm on the TiO2 surface. The incorporation of Ag on the TiO2 surface significantly influenced the optical properties in the region of 400–500 nm because of the surface plasmon resonance effect. The dye-sensitized solar cells (DSSCs) assembled with the Ag@TiO2-modified photoanode demonstrated an enhanced solar-to-electrical energy conversion efficiency (4.86%) compared to that of bare TiO2 (2.57%), due to the plasmonic effect of Ag. In addition, the Ag nanoparticles acted as an electron sink, which retarded the charge recombination. The influence of the Ag content on the overall efficiency was also investigated, and the optimum Ag content with TiO2 was found to be 2.5 wt%. The enhanced solar energy conversion efficiency of the Ag@TiO2 nanocomposite makes it a promising alternative to conventional photoanode-based DSSCs

Aerosol assisted chemical vapour deposited (AACVD) of TiO2 thin film as compact layer for dye-sensitised solar cell

Compact TiO2 has been introduced onto the surface of an indium tin oxide glass slide (ITO), using an aerosol-assisted chemical vapour deposition method. This serves as a blocking layer for a dye-sensitised solar cell (DSSC). The thickness of the compact TiO2 could be controlled by deposition time. X-ray diffraction and Raman spectroscopy analyses reveal that the compact TiO2 is made up of mixed anatase and rutile phases. The field emission scanning electron microscopy image displays a pyramidal morphology of the compact TiO2. A layer of P25 paste was then smeared onto the compact TiO2-modified ITO, using the doctor's blade method. A post-treatment procedure was applied to remove the contaminants from the prepared hybrid film, by immersing in a hydrochloric acid solution. The photoelectrochemical measurements and J–V characterisation of the hybrid film show an approximately fourfold increase in photocurrent density generation (114.22 µA/cm2), and approximately 25% enhancement of DSSC conversion efficiency (4.63%), compared to the acid-treated P25 paste alone (3.68%)

Silver/titania nanocomposite-modified photoelectrodes for photoelectrocatalytic methanol oxidation

Silver deposited titania (Ag/TiO2) nanocomposite thin films were fabricated by the simple sonochemical deposition of Ag on preformed aerosol-assisted chemical vapor deposited TiO2 thin films. The photelectrocatalytic performance of a newly fabricated Ag/TiO2-modified photoelectrode was studied for methanol oxidation under simulated solar AM 1.5G irradiation (100 mW/cm2). The Ag/TiO2-modified photoelectrode showed a photocurrent density of 1 mA/cm2, which is four times that of an unmodified TiO2 photoelectrode. The modification of Ag on the TiO2 surface significantly enhanced the photoelectrocatalytic performance by improving the interfacial charge transfer processes, which minimized the charge recombination. Density functional theory (DFT) calculation studies revealed that methanol could be easily adsorbed onto the Ag surfaces of Ag/TiO2 via a partial electron transfer from Ag to methanol. The newly fabricated Ag/TiO2-modified photoelectrode could be a promising candidate for photoelectrochemical applications

Effect of electropolymerization potential on the preparation of PEDOT/graphene oxide hybrid material for supercapacitor application

Conducting polymer poly(3,4-ethylenedioxythipohene) (PEDOT) hybrid with carbon-based material, graphene oxide (GO), was prepared for supercapacitor application. Different applied potentials were employed in order to study the effect of electropolymerization potential on PEDOT/GO thin film. Field emission scanning electron microscopy (FESEM) images showed that PEDOT/GO possessed more pronounced wrinkle paper-like sheet surface morphology as the potential increased from 1.0 to 2.0 V. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy revealed that GO was successfully incorporated into PEDOT during electropolymerization. The cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements revealed that the PEDOT/GO composite electropolymerized at the applied potential of 1.2 V exhibited a maximum specific capacitance of 115.15 F/g with energy density and power density of 13.60 Wh/kg and 139.09 W/kg, respectively at current density 0.3 A/g. The EIS result showed that the Rct decreased as the electropolymerization potential rose from 1 V to 1.2 V and increased when the electropolymerization further increased to 2 V due to a large electron transfer resistance that makes the rate of charge transfer becomes slower

Adapting An Existing Example-Based Machine Translation (EBMT) System For New Language Pairs Based On An Optimized Bilingual Knowledge Bank (BKB).

Sourcing for large amount of text and translating them are some of the challenges in building an Example-Based Machine Translation (EBMT) system. These big amounts of translated texts are annotated into the S-SSTC format to cover an extensive vocabulary and sentence structures. However, the Bilingual Knowledge Bank (BKB), which is a collection of the S-SSTCs, will normally contain redundancy. Hence, the idea of an optimized BKB is born. An optimized BKB (redundancy reduced; is smaller in size but is as equally extensive in term of its sentence structure coverage compared to an un-optimized BKB. Therefore, an optimized BKB enhances the performance of the EBMT. In this paper, we introduce the idea of an optimized BKB and propose it to be re-used to effectively construct new BKBs in order to adapt an existing EBMT for new language pairs