Design & development of a novel glass polyalkenoate cement for sternal fixation and repair, in the event of median sternotomy surgery

Median sternotomy surgery is the gold standard for cardiac/thoracic procedures such as open-heart surgery. With over one million median sternotomy surgeries performed worldwide every year, sternal wound complications pose a serious risk to the health of affected patients. Various techniques have been used for sternal fixation including wiring, plate-screw systems and cementing. The ideal sternal closure device is the one which has mechanical properties suited to the local environment, biocompatibility, radio-opacity, cost-effectiveness and ease of removal when necessary. None of the techniques that have been utilized for sternal fixation to date address all of these requirements. Glass polyalkenoate cements (GPCs) have a long history of use in restorative and orthodontic dentistry and ear, nose and throat (ENT) surgery but have yet to be indicated for musculoskeletal applications. This dissertation relates to the development of new GPC-based adhesives for use in sternal closure. A series of novel glasses based on the system 48SiO2-(36-X) ZnO-6CaO-8SrO-2P2O5-XTa2O5 with X varying from 0.0 to 8.0 mole percentage were fabricated and characterized. The structural features as a function of Ta2O5 content were investigated by network connectivity (NC) calculations, x-ray diffraction (XRD), particle size analysis (PSA), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance (MAS-NMR). The thermal properties of the glasses were obtained by performing simultaneous thermal analysis (STA). The effect of glass structure on pH and solubility was also evaluated. The formulated glasses were used to prepare GPC adhesive materials and tested for their suitability for sternal fixation. The data collected has confirmed that substituting up to 0.5 mole percentage of ZnO with Ta2O5 in the glass system under study resulted in the formation of adhesives that are deemed suitable for sternal fixation. The formulated cements, based on the use of glasses containing no greater than 0.5 mole percentage of Ta2O5 have rheology, strength, radiopacity, antibacterial and in-vitro behavior suitable for sternal fixation. To the best knowledge of the candidate, this dissertation is the first to report the use of tantalum-containing GPC-based adhesives for sternal closure. Based on the obtained results, the formulated adhesives can be used in conjunction with sternal cable ties (current standard method) to offer optimal fixation for patients and reduce post-operative complications such as bacterial infection and pain from micro-motion.

Design & development of a novel glass polyalkenoate cement for sternal fixation and repair, in the event of median sternotomy surgery

Median sternotomy surgery is the gold standard for cardiac/thoracic procedures such as open-heart surgery. With over one million median sternotomy surgeries performed worldwide every year, sternal wound complications pose a serious risk to the health of affected patients. Various techniques have been used for sternal fixation including wiring, plate-screw systems and cementing. The ideal sternal closure device is the one which has mechanical properties suited to the local environment, biocompatibility, radio-opacity, cost-effectiveness and ease of removal when necessary. None of the techniques that have been utilized for sternal fixation to date address all of these requirements. Glass polyalkenoate cements (GPCs) have a long history of use in restorative and orthodontic dentistry and ear, nose and throat (ENT) surgery but have yet to be indicated for musculoskeletal applications. This dissertation relates to the development of new GPC-based adhesives for use in sternal closure. A series of novel glasses based on the system 48SiO2-(36-X) ZnO-6CaO-8SrO-2P2O5-XTa2O5 with X varying from 0.0 to 8.0 mole percentage were fabricated and characterized. The structural features as a function of Ta2O5 content were investigated by network connectivity (NC) calculations, x-ray diffraction (XRD), particle size analysis (PSA), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance (MAS-NMR). The thermal properties of the glasses were obtained by performing simultaneous thermal analysis (STA). The effect of glass structure on pH and solubility was also evaluated. The formulated glasses were used to prepare GPC adhesive materials and tested for their suitability for sternal fixation. The data collected has confirmed that substituting up to 0.5 mole percentage of ZnO with Ta2O5 in the glass system under study resulted in the formation of adhesives that are deemed suitable for sternal fixation. The formulated cements, based on the use of glasses containing no greater than 0.5 mole percentage of Ta2O5 have rheology, strength, radiopacity, antibacterial and in-vitro behavior suitable for sternal fixation. To the best knowledge of the candidate, this dissertation is the first to report the use of tantalum-containing GPC-based adhesives for sternal closure. Based on the obtained results, the formulated adhesives can be used in conjunction with sternal cable ties (current standard method) to offer optimal fixation for patients and reduce post-operative complications such as bacterial infection and pain from micro-motion.

Studying the Effect of High Substrate Temperature on the Microstructure of Vacuum Evaporated TAPC: C60 Organic Solar Thin Films

Organic solar cells (OSCs), also known as organic photovoltaics (OPVs), are an emerging solar cell technology composed of carbon-based, organic molecules, which convert energy from the sun into electricity. Key for their performance is the microstructure of the light-absorbing organic bulk heterojunction. To study this, organic solar films composed of both fullerene C60 as electron acceptor and different mole percentages of di-[4-(N,N-di-p-tolyl-amino)-phenyl]-cyclohexane (TAPC) as electron donor were evaporated in vacuum in different mixing ratios (5, 50 and 95 mol%) on an ITO-coated glass substrate held at room temperature and at 110 °C. The microstructure of the C60: TAPC heterojunction was studied by grazing incidence wide angle X-ray scattering to understand the effect of substrate heating. By increasing the substrate temperature from ambient to 110 °C, it was found that no significant change was observed in the crystal size for the C60: TAPC concentrations investigated in this study. In addition to the variation done in the substrate temperature, the variation of the mole percent of the donor (TAPC) was studied to conclude the effect of both the substrate temperature and the donor concentration on the microstructure of the OSC films. Bragg peaks were attributed to C60 in the pure C60 sample and in the blend with low donor mole percentage (5%), but the C60 peaks became nondiscernible when the donor mole percentage was increased to 50% and above, showing that TAPC interrupted the formation of C60 crystals.

Support Vector Machine-based Soft Sensors in the Isomerisation Process

This paper presents the development of soft sensor empirical models using support<br /> vector machine (SVM) for the continual assessment of 2,3-dimethylbutane and 2-methylpentane mole percentage as important product quality indicators in the refinery isomerisation process. During the model development, critical steps were taken, including selection and pre-processing of the industrial process data, which are broadly discussed in this paper. The SVM model results were compared with dynamic linear output error model and nonlinear Hammerstein-Wiener model. Evaluation of the developed models on independent data sets showed their reliability in the assessment of the component contents. The soft sensors are to be embedded into the process control system, and serve primarily as a replacement during the process analysersb failure and service periods.

ACETONE RECOVERY USING BATCH DISTILLATION

This study focuses on determining the feasibility of obtaining maximum mole percentage of acetone (99 mole%) in the distillate stream from a 3 mole% acetone waste stream using batch distillation. The device which is used in this work has eight trays that will act as the stages of the batch distillation. The effects of varying reflux ratio and heat load (power) on acetone concentration were studied. Moreover, the operating conditions for the bath distillation column such as flooding and weeping with the extreme limits of operation were considered. The temperatures were also be recorded at each tray. The McCabe-Thiele method was used to determine the theoretical number of trays and compared with actual trays (column efficiency). For a chemical analysis of acetone/water compositions a refractometer was used for a chemical analysis, known acetone/water concentrations were analysed and used to construct a calibration curve. The results obtained showed that, the acetone concentration increases with increasing reflux ratio until a highest concentration was reached. Then, the concentration gradually decreases with increasing reflux ratio. However, the distillate stream with 99 mole % acetone was achieved at a reflux ratio of R=3 and at both powers 0.5 kw and 0.7 kw. Finally, the highest overall column efficiency reached by this work was about 75%.

The Study of Physical and Optical Properties of Barium Borophosphate Glasses

This research reports on the physical and optical properties of three series of borophosphate glasses combined with barium oxide (BaO), following BaBP-A, BaBP-B and BaBP-C, that were prepared by a melting and quenching process. The density, molar volume, refractive index and absorption spectra were investigated the effect of BaO on different glass structures. The results show that the densities and refractive index of the glass samples increased as the BaO (BaBP-A and BaBP-B) and B2O3 (BaBP-C) mole percentage increased. The molar volume of the glasses shows the adversative trend as the density: the molar volume decreased as the BaO and B2O3 content increased. The absorption spectra of all glass samples were slightly shifted to the longer wavelength, ultraviolet 250-350 nm, with increasing the concentration of BaO.

Synthesis of Silver Nanoparticles by a Sonochemistry Method Useful for Two-Dimentional Nanoparticle Arrays

Silver nanoparticles were synthesized by a sonochemistry method by using silver stearate and triphenylphosphine as silver precursor and reduction accelerator respectively. The experimental conditions that influence the formation and organization of the particles were investigated, and the particles were characterized by TEM. Results showed that well-ordered two-dimentional (2D)-monolayer was formed after solvent evaporation on a carbon-coated copper TEM grid at the optimal experimental conditions which was that the mole percentage of the amount of reducing agent and triphenylphosphine to silver precursor was 10% and 50% respectively, and the ultrasound power was set at 60% (relative to the maximum ultrasound power value of the machine).

Czochralski Crystal Growth of Zinc Oxide-Tellurium Oxide System

ABSTRACTCzochralski technique was employed in an attempt to grow a single crystal of the system ZnO-TeO2. A good quality grown crystal is expected to be transparent with a very light yellow color. The crystals exhibit a high resistivity of the order of 1013 Ω-cm. Different mole percentages have been tested for growth. Several attempts were performed to pull a single crystal. It was found that the best mole percentage of ZnO-TeO2 is 35.5:64.5. The pulled material grows uniformly, such that necking and conning are noticed. The pulled material contained multiple single crystals which were isolated and studied. Each one of them was transparent. Some properties will be presented. The pulled material of the 40:60 ZnO-TeO2 mole percentage returned four phases. Two of these phases are very uncommon.

The Effects of Slider Material on the Gasification of Carbon

The influence of alumina and titanium carbide, components of magnetic recording sliders, on the carbon gasification reaction was investigated. Pure alumina and titanium carbide powders were each combined with graphite powder and subjected to thermogravimetric analysis (TGA). The molar ratio ranged from 0 to 20 mol percent; graphite powder was the balance. From the thermogravimetric analysis, the activation energy Ea of the reactions was determined. It was found that the activation energy for carbon gasification reduced slightly for increasing alumina mole percentage. Titanium carbide additions markedly increased the activation energy. This increase indicates a competitive oxidation reaction that forms titanium oxide, as confirmed by X-ray diffraction (XRD). As a result of these observations, titanium oxide was also mixed with graphite powders and analyzed by TGA. Titanium oxide has an activation energy behavior that becomes more complex with increasing mole percentage: the activation energy first increases and then decreases. These data are presented and the oxidation reaction is proposed.