Influence of Al2O3/ Y-TSZ Mixture as Filler Loading on the Radiopacity of PMMA Denture Base Composites

AbstractThe radiopacity of alumina/yttrium stabilizer zirconia (Al2O3/Y-TSZ) particles with nitrile butadiene rubber (NBR) dispersed in PMMA denture base material has been investigated. PMMA matrix without filler was prepared from PMMA powder with 0.5% benzoyl peroxide (PBO) as the control material. The similar PMMA matrix was mixed with Al2O3/Y-TSZ (1:1) together with NBR particles as the reinforcement. The amount of NBR was fixed at 7.5wt %, however, Al2O3/Y-TSZ varied from 1 to 10wt %, respectively. Samples with 4mm thickness for each composition were irradiated using 60 KV, 10mA, 0.4 s to examine their radiopacity. This radiopacity was compared to radiopacity of aluminum plate which having the same thickness. The result shows that the radiopacity (i.e. the lower optical density the higher radiopacity) of reinforced PMMA matrix slightly increased from 1.40 to 1.05, respectively, with the increased of filler loading compared to unreinforced PMMA matrix

Lithofacies and Sedimentation of Organic Matter in Fine Grained Rocks of Nanggulan Formation in Kulon Progo, Yogyakarta

Fine grained rocks especially shale play a significant role in shale hydrocarbon system. Research on Eocene Nanggulan shale becomes an interest lately since this shale is considered as prospective interval for shale gas source. It potentially contains significant organic matter because coaly sediment is found in this formation as well. Nanggulan Formation fine grained rocks was deposited in various depositional environment from estuary – shallow marine. This paper integrates the result of lithofacies and depositional environment analysis with organic geochemical data to understand the sedimentation process of organic matter. Samples were taken from cores. The result of 14 geochemically analysed samples shows Total Organic Carbon (TOC) content between 0.36–1.00 % for fin e grained rocks (shales) and 12.80 % for coaly shales. Nine samples are categorized as fair and 2 samples are categorized as good source rock. The depositional environment of Nanggulan Formation sediment, which was shallow marine at Late Eocene and estuary (salt marsh) at Early Eocene, produced sediment with higher TOC. Whereas the deposition of sediment in estuary (tidal flat) at Middle Eocene produced lower content of TOC. Vulcanic activity at Middle Eocene also caused less organic material preservation because it produced abundant inorganic material

Investigation on Flux Characteristics of Field Excitation Flux Switching Machine with Single FEC Polarity

AbstractFlux switching machines (FSMs) that consist of all flux sources in the stator have been developed in recent years due to their definite advantage of single piece robust rotor structure suitable for high speed applications. They can be categorized into three groups that are permanent magnet (PM) FSM, field excitation (FE) FSM, and hybrid excitation (HE) FSM. Both PMFSM and FEFSM has only PM and field excitation coil (FEC), respectively as their main flux sources, while HEFSM combines both PM and FECs. Among these FSMs, the FEFSM offers advantages of low cost, simple construction and variable flux control capabilities suitable for various performances. In this paper, design study and flux interaction analysis of 24S-10P FEFSM with single direction of FEC winding is presented. Initially, design procedures of the FEFSM including parts drawing, materials and conditions setting, and properties setting are explained. Then, coil arrangement tests are examined to confirm the machine operating principle and position of each armature coil phase. Finally, the flux interaction between DC FEC and armature coil, FEC flux capabilities at various current condition, and initial torque are also investigated

Effect of maleated compatibiliser (PBS-g-MA) addition on the flexural properties and water absorption of poly(butylene succinate)/kenaf bast fibre composites

Poly(butylene succinate) (PBS) composites with 30 wt.% loading of kenaf bast fibre (KBF) were compatibilised with 5 wt.% maleated PBS (PBS-g-MA). The maleic anhydride (MA) concentration in the compatibiliser was either 3, 5, 7 or 10 phr. In general, the compatibilised composites showed better flexural properties than the un-compatibilised composite. The highest increment in the flexural strength and modulus of 12.7 and 8.9%, respectively, were obtained with the addition of PBS-g-MA with MA concentration of 5 phr. Compatibilised and un-compatibilised PBS/KBF composites were immersed in distilled water for 90 days. The absorption of water by all the composites was observed to follow Fick’s law. The equilibrium moisture content, Mm, of the composites with PBS-g-MA at 3, 5 and 7 phr of MA concentrations was lower than that of the un-compatibilised composite due to improved fiber-matrix interfacial adhesion and reduction of voids content. Both un-compatibilised and compatibilised composites showed dimensional instability after the water absorption. This was probably due to the degradation of the fibre-matrix interfacial adhesion and fibre integrity. The flexural properties of these composites decreased after the water absorption. After re-drying only some of the flexural properties were recovered from plasticizing effect of water

Development and Evaluation of Surface Modified Poly (lactic acid) Microsphere via Irradiation Techniques for Drug Delivery System

AbstractPoly (lactic acid) (PLA) has been used in medical field because it is biocompatible, biodegradable and has good mechanical properties. However, its surface characteristic which is hydrophobic and chemically inert is not suitable as a carrier in drug delivery system. Purpose of this study is to modify and improve PLA microspheres surface by grafting hydrophilic monomers onto its surface via irradiation techniques. Two sets of PLA microspheres with and without hydrophilic monomers were irradiated using high energy irradiations which are electron beam and Gamma (γ) rays respectively. Although dose used in irradiating samples were same for both electron beam and γ-rays, but the dose rate were different where electron beam has the higher dose rate. Free radicals will be formed when a matter is irradiated with ionising radiation and these radicals will interact with monomers and initiate grafting. Three hydrophilic monomers were used in this study i.e. Acrylic Acid (AA), Acrylamide and Maleic Anhydride (MAH). Surface modified PLA microspheres were characterised using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). PLA microspheres surface were successfully modified and grafted with selected monomers and confirmed by FTIR results. The degrees of grafting were found to be dependent on irradiation dose and dose rate of irradiation as well as monomer used in the grafting. SEM shows surface of PLA microsphere after surface modification is rougher compared to before surface modification

Rheological evaluation of the fabrication parameters of cellulose acetate butyrate membrane on CO2/N2 separation performance

The rise in emission of greenhouse gases (GHGs) mainly carbon dioxide (CO2) in recent years due to rapid development of modern civilisation, has been listed as the primary contributor to global warming. To address this global issue, membrane technology was applied and developed intensively because of its superior performance in terms of efficiency and economic advantages. In this study, the cellulose acetate butyrate (CAB) polymer was selected as the polymer matrix material since it exhibited excellent film-forming properties. In addition, the wet-phase inversion technique was adopted to synthesise the membrane based on different casting conditions. The optimum outcomes of the fabrication conditions were then characterised with the scanning electron micrograph (SEM) to determine the best CAB membrane for CO2/N2 separation. The results showed that CAB-70000 fabricated with 4 wt% of CAB polymer concentration, casting thickness of 250 µm, solvent evaporation time of 5 minutes, and 30 minutes of solvent exchange for isopropyl alcohol and n-hexane, exhibited the best gas separation performance. Further, CAB-70000 showed an average selectivity of 6.12 ± 0.09 and permeance up to 227.95 ± 0.39 GPU for CO2 and 37.28 ± 0.54 GPU for N2, respectively. In summary, this study is expected to show a detailed outline of the future direction and perspective of the novel CAB polymeric membrane that is suitable to be applied in the industry, and serves as an insight for researchers and manufacturers working in the related field of gas separation

Satellite Estimation of Spectral Surface UV Irradiance

The local variability of UV irradiance at the Earth's surface is mostly caused by clouds in addition to the seasonal variability. Parametric representations of radiative transfer RT calculations are presented for the convenient solution of the transmission T of ultraviolet radiation through plane parallel clouds over a surface with reflectivity R(sub s). The calculations are intended for use with the Total Ozone Mapping Spectrometer (TOMS) measured radiances to obtain the calculated Lambert equivalent scene reflectivity R for scenes with and without clouds. The purpose is to extend the theoretical analysis of the estimation of UV irradiance from satellite data for a cloudy atmosphere. Results are presented for a range of cloud optical depths and solar zenith angles for the cases of clouds over a low reflectivity surface R(sub s) less than 0.1, over a snow or ice surface R(sub s) greater than 0.3, and for transmission through a non-conservative scattering cloud with single scattering albedo omega(sub 0) = 0.999. The key finding for conservative scattering is that the cloud-transmission function C(sub T), the ratio of cloudy-to clear-sky transmission, is roughly C(sub T) = 1 - R(sub c) with an error of less than 20% for nearly overhead sun and snow-free surfaces. For TOMS estimates of UV irradiance in the presence of both snow and clouds, independent information about snow albedo is needed for conservative cloud scattering. For non-conservative scattering with R(sub s) greater than 0.5 (snow) the satellite measured scene reflectance cannot be used to estimate surface irradiance. The cloud transmission function has been applied to the calculation of UV irradiance at the Earth's surface and compared with ground-based measurements

Proceeding of Annual International Conference Syiah Kuala University 2011

The main objective of this conference is to provide a forum for researchers, government officers, educators, students and industries. This forum is a media for exchange ideas, communicate and discuss research findings and new advancement in science from multi-disciplines, and explore possible avenues to foster academic as well as scientific activities at international level

An All-Optical Frequency Up/Down-Converter Utilizing Stimulated Brillouin Scattering In A Trf And Dcf For Rof Application

A frequency up and down conversion is proposed based on stimulated Brillouin scattering (SBS) for Radio-over-fiber (RoF) system. Microwave frequency up conversion from 2GHz to 12.5GHz and microwave frequency down conversion from 12.5GHz to 1.8GHz with largest Intermediate Frequency (IF) power of -32dBm is successfully demonstrated. The up conversion is based on the 1st Stokes of Brillouin fiber laser in Truewave reach fiber (TWF) and the down conversion is based on 1st AntiStokes of Brillouin fiber laser in Dispersion compensating fiber (DCF)