Applied Mechanics and Materials Vol. 842

Abstract: Stress distributions that occur in the free end second premolar tooth and its root form dental implant replacement were evaluated using finite element method. In the modelling process, 3D reconstructions were performed. Instead of doing it manually, the 3D reconstruction in this paper was done using cone beam computed tomography (CBCT) scanning process. The 3D reconstruction method used in this paper, is considerably faster than the traditional manual 3D reconstruction method. In order to mimic the actual biting force, static load of 200 N was modelled in the vertical direction parallel to the long axis of the tooth which is placed on bite contact at second premolars and dental implant crown. The stress result on root form dental implant is generally higher than the stress on the natural free end second premolar tooth. The stress concentration locations on root form dental implant were also found and will be used in the future to improve the design of root form dental implant.

Abstract: Water confined in carbon nanotubes (CNTs) under the influence of an electric field has interesting properties that are potential for nanofluidic-based applications. With molecular dynamics simulations, this work shows that the electric field induces formation of ordered structures of water molecules in the CNTs. Formation of the ordered structures strengthens the electrostatic interaction between the water molecules. As a result, water strongly prefers to fill CNTs over methanol and it produces a separation effect. Interestingly, the separation effect with the electric field does not decrease for a wide range of CNT diameter.

Abstract: This paper presents design and fabrication of portable desalination chamber utilizing water permeable polyethersulfone (PES) membrane. The chamber has four stages of desalination process. Each stage has a membrane clamped by filter plate to desalinate sea water and an outlet to qualify the desalinated water from each stage. The chamber works without electrical power, hence desalination process can be carried out in remote areas where electricity source is difficult to find. The water stream is used to test the pumping system of the chamber to pump the water from the water container. The test shows that the pumping system of the chamber is working properly in delivering water to each stage of the chamber without any leakage. The membrane used in each chamber is a modified PES membrane which has high water permeability. Water permeability of the membrane will guarantee that the salt water will permeate easily through the membrane porous during desalination process, hence results in producing fresh water at the final outlet.

Abstract: Due to the increase of industrial activities both at local and national level, the quality of water in Indonesia is significantly degraded by time. Heavy metal wastes from industrial activities have become serious contaminants in the water. The contamination dangers human’s health since most people living near the river-bank still use the water to fulfill their daily needs. In this paper, we present the fabrication of Hydroxyapatite (HA) disc as a filtration medium in waste water treatment system. HA is one of biomaterial which can be derived from animal’s bone and is capable to absorb dangerous heavy-metal contaminants such as lead (Pb) in the water. Our produced HA was made by extracting cortical bovine bones into cortical bone HA powder. The cortical bovine bones were processed using physical method by heating the bones at 900oC to gained powder then followed by forming green bodies and sintering at 1000oC and 1400oC. Those powders were then pressed into a disc form and will be used as filtration media in HA modular purifier. SEM/EDX results show the disk surface has interconnected micropores and Ca/P ratio value on sintered HA disc at 1000oC and 1400oC are 2.20 and 1.85, respectively.

Abstract: There is no doubt that currently the use of electronic products and appliances has escalated tremendously in all over the world including Indonesia. This situation obviously also causes the increase of e-waste (electronic waste). Without proper treatment, e-waste will eventually cause environmental degradation as most of substances in electronic products contain hazardous materials. Proper treatment of e-waste will prevent environmental problems and at the same time will preserve natural resources as most of the materials even components in electronic products are reusable or recyclable. In many developed countries the collection of e-waste has been regulated and professionally managed. The situation is different in Indonesia as there is low law enforcement to handle e-waste at national and local levels. This paper will present a research utilizing Fuzzy Analytical Hierarchy Process (AHP) to determine the best e-waste collection scenario for Indonesia. Criteria and sub-criteria that need to be considered for future implementation as well as recommendation for e-waste collection in Indonesia are presented as the result of the research.

Abstract: Lead (Pb) is one of common heavy metal that has been shown to be very useful tracers of environmental pollution. The consequences of urbanization process can cause not only economic growth but also negatively impact on the quality of water and soil. Therefore the objective of this research is to know the potential contamination of lead in soil of urban area. The soil samples were conducted by batch leaching experiment. In surface soil, lead in soil of Pakem area varies from 2.01ppm to 5.13 ppm with average value of 3.02 ppm and Merapi area ranges from 1.84 ppm to 3.41ppm with average value of 2.42 ppm. In urban area, lead varies from 4.18 to 14.88 ppm with average of 9.93 ppm. Lead in urban soil is higher than Pakem and Merapi soil. The potential contamination of lead in urban soil is occurred with respect to urbanization and human activities. The value of lead is shown with the average of 3 ppm for Caturtunggal, Depok District, 6.53 ppm in Mantrijeron District and 9.82 ppm for Kotagede District in Yogyakarta city. The result of lead distribution in Kotagede District is the highest concentrated and it is followed by Mantrijeron District and Caturtunggal, Depok District.