Risk management is a particular form of decision making within project management, and it is about making better decisions with regard to the management of projects. Risk identification process, as an early process in risk management, is... more
Risk management is a particular form of decision making within project management, and it is about making better decisions with regard to the management of projects. Risk identification process, as an early process in risk management, is essential and must be comprehensive. Routine approaches to risk identification in construction industry have some drawbacks both in the tools and the concept, due to inappropriate distinction and classification of risk source, event, and impact, and due to misinterpretation of the “multiple-source risk” concept. In this paper, based on an experiment, a new approach to risk identification and development of breakdown structures proposed and implemented to improve the “multiple-source risk” concept throughout the risk management processes in construction projects.
This study aim to synthesize bioceramic from Paphia undulata shell by using dry technique in order to proposed new bioceramic for human bone repair application. The clam shells obtained from the fisherman of Kuala Perlis coast were turned... more
This study aim to synthesize bioceramic from Paphia undulata shell by using dry technique in order to proposed new bioceramic for human bone repair application. The clam shells obtained from the fisherman of Kuala Perlis coast were turned into a fine powder using an agate mortar. Since the clam shells contain high percentage of calcium carbonate, calcium carbonate powder turned to calcium oxide (CaO) by a calcinations process and the calcined powder then mix with water to form calcium hydroxide. The crystalline phases of the mixtures were greatly dependent on the mixing ratio (wt %) of the calcium hydroxide to phosphoric acid. In a wide mixing ratio range of 1:1.1-1:1.3 wt%, hydroxyapatite were synthesized and palletized. All samples were sintered to determine most suitable sintering temperature to fabricate bioceramics for bone substitute materials. The composition of the samples had been analyzed by using X-ray diffractometry (XRD) spectroscopy. In addition, the mechanical properties of samples were characterized using compression test. The result obtained show hydroxyapatite was successfully produced with mixing ratio Ca/P is 1:1.2 wt% at 750°C sintering temperature.
Analysis of the total surface energy γ T and its three components as established by the van Oss-Chaudhury-Good Theory (vOCG) is conducted via Three Liquid Contact Angle Analysis (3LCAA). γ T is correlated with the composition of the top... more
Analysis of the total surface energy γ T and its three components as established by the van Oss-Chaudhury-Good Theory (vOCG) is conducted via Three Liquid Contact Angle Analysis (3LCAA). γ T is correlated with the composition of the top monolayers (ML) obtained from High-Resolution Ion Beam Analysis (HR-IBA). Control of γ T enables surface engineering for wafer bonding (Nano-Bonding TM) and/or epitaxial growth. Native oxides on boron-doped p-Si(100) are found to average γ T of 53 ± 1.4 mJ/m 2) and are always hydrophilic. An HF in methanol or aqueous HF etch for 60 s always renders Si(100) hydrophobic. Its γ T decreases by 20% to 44 ± 3 mJ/m 2 in HF in methanol etch and by 10% to 48 ± 3 mJ/m 2 in aqueous HF. On the contrary, GaAs(100) native oxides are found to always be hydrophobic. Tellurium n+-doped GaAs(100) yields an average of γ T of 37 ± 2 mJ/m 2 , 96% of which is due to the Lifshitz-Van der Waals molecular interactions (γ LW = 36 ± 1 mJ/m 2). However, hydrophobic GaAs(100) can be made highly hydrophilic. After etching, γ T increases by almost 50% to 66 ± 1.4 mJ/m 2. 3LCAA shows that the γ T increase is due to electron acceptor and donor interactions, while the Lifshitz-van der Waals energy γ LW remains constant. IBA combining the 3.039 ± 0.01 MeV oxygen nuclear resonance with <111> channeling, shows that oxygen on Si(100) decreases by 10% after aqueous HF etching, from 13.3 ± 0.3 monolayers (ML) to 11.8 ± 0.4 ML 1 hour after etch.Te-doped GaAs(100) exhibits consistent oxygen coverage of 7.2 ± 1.4 ML, decreasing by 50% after etching to a highly hydrophilic surface with 3.6 ± 0.2 oxygen ML. IBA shows that etching does not modify the GaAs surface stoichiometry to within 1%. Combining 3LCAA with HR-IBA provides a quantitative metrology to measure how GaAs and Si surfaces can be altered to a different hydroaffinity and surface termination.
The analytical techniques using ion beams are powerful tools for surface analysis of solid materials. Constituent elements are important in determining the biocompatibility and corrosion resistance of a biomaterial implant. The focus of... more
The analytical techniques using ion beams are powerful tools for surface analysis of solid materials. Constituent elements are important in determining the biocompatibility and corrosion resistance of a biomaterial implant. The focus of this article is on the application of ion beam analysis towards quantifying the composition of calcium phosphate based biomaterials. Thin films of calcium phosphate bioceramics were prepared on Si and Ti substrates using ion beam sputter deposition (IBSD) and ion beam assisted sputter deposition (IBASD) methods. Precise amounts of calcium, phosphorus, oxygen and hydrogen in these thin films are determined by combining four ion beam analysis techniques. The simultaneous application of proton induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were utilized to quantify composition and amounts of elements heavier than helium. Elastic recoil detection analysis (ERDA) was used to determine hydrogen content while resonance-enhanced RBS (RE-RBS) was utilized to measure oxygen concentration. The amount of assisting ion beam current density during deposition affected the concentration ratios of Ca, O and H to P. Combination of different ion beam analysis methods is useful in characterizing the elemental composition and distribution of composite biomaterials.
Rare-earth silicides have been studied by RBS spectrometry and X-ray diffraction. 72C and 4He RBS at 10 and 2 MeV, respectively, were used in order to compare heavy ion RBS (HIRBS) with conventional 4He RBS, 72C RBS gives better mass... more
Rare-earth silicides have been studied by RBS spectrometry and X-ray diffraction. 72C and 4He RBS at 10 and 2 MeV, respectively, were used in order to compare heavy ion RBS (HIRBS) with conventional 4He RBS, 72C RBS gives better mass resolution for heavy elements (M > 28 amu), but slightly poorer depth resolution in comparison with conventional RBS. In addition, the limited accuracy with which stopping power data of ~2C are known limits the accuracy of HIRBS.
In this paper the influence of surface topography on Rutherford backscattering spectrometry (RBS) is discussed. (Cu/Fe/Pd) multilayers with total thickness of about 10 nm were deposited by physical vapor deposition on self-organized array... more
In this paper the influence of surface topography on Rutherford backscattering spectrometry (RBS) is discussed. (Cu/Fe/Pd) multilayers with total thickness of about 10 nm were deposited by physical vapor deposition on self-organized array of SiO2 nanoparticles with the size of 50 nm and 100 nm. As a reference, the multilayered systems were also prepared on flat substrates under the same conditions. After the deposition, morphology of the systems was studied by scanning electron microscopy (SEM), while chemical analysis was performed using Rutherford backscattering spectrometry. It was found that the RBS spectra and determined compositions for flat and patterned multilayers differ. The difference is discussed by taking into account the effect of additional inelastic scattering and energy straggling occurring due to developed topography of patterned systems. Then, the multilayers were annealed in 600 °C in order to obtain FePdCu alloy. The phenomenon of solid-state dewetting resulted in the formation of isolated alloy islands on the top of SiO2 nanoparticles. The SEM and RBS analysis were repeated showing correlation between the size distribution of obtained alloy islands and broadening of peaks appearing in RBS spectra.
