Effects of sintering and zirconmullite doping on nanostructural vacancies of bovine hydroxyapatite by positron techniques

In this study, the nanostructural vacancy behavior of bovine derived hydroxyapatite (BHA) doped with powder zirconmullite (ZM) contents of 5, 7.5, 10 and 12.5 wt.% were presented at sintering temperatures of 1000, 1100, 1200 and 1300°C. ZM-doped BHA (ZM-BHA) was characterized by X-ray diffraction and positron annihilation lifetime spectroscopy (PALS). Density and hardness behavior were measured with respect to increasing sintering temperature. PALS results indicate that the longest lifetime component τ₃ of ortho-positronium (o-Ps) localized at open spaces is attributed to the vacancy site and almost constant with the ZM contents and the sintering temperatures to have a mean value of 0.680 ns (corresponding to the radius of 0.997 nm). This average value is ascribed to the OH group defects along the main crystalline line. On the other hand, the o-Ps intensity attributed to the number of vacancy sites increases almost linearly with ZM additives and sintering temperatures. The intensity is also related to the density and hardness of ZM-BHA in terms of ZM contents.     

Fuzzy expert system for troubleshooting of the deodorizer unit in a palm oil refining plant

In this paper, a troubleshooting technique is developed to provide a sequence of necessary actions during deodorizer unit failure in a palm oil refinery. This paper introduces a fuzzy expert system that incorporates the knowledge of experienced plant workers in dealing with the complex problems of the palm oil deodorizer. The presented methodology uses both qualitative and quantitative data. Qualitative data are collected from several interview sessions with the technical staff in a palm oil refinery. Quantitative data are gathered from various sources, such as control and monitoring systems. The qualitative data are analyzed to discover the possible pattern of faults in the deodorizer failure. This tool can diagnose possible faults and provide a sequence of necessary actions when deodorizer failure occurs. The obtained results show the developed deodorizer troubleshooting tool is useful to guide plant workers/operators in diagnosing the possible faults and abnormalities during the troubleshooting process, as well as to provide field training for inexperienced staff.     

Diffusion coefficients and phase equilibria of carbon dioxide–ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) system

This article presents the mutual diffusion coefficients of a carbon dioxide–ionic liquid, [bmim][PF₆], system at temperatures of 313.15 and 323.15 K and pressures of 5 and 8 MPa. In order to estimate the diffusion coefficients, we have carried out experiments to find time-dependent carbon dioxide solubilities in the ionic liquid and then fit a transport model to the data. In a system containing high pressure carbon dioxide and ionic liquid, carbon dioxide dissolves in the liquid until its equilibrium mole fraction is reached. During this process, the position of the liquid–vapour interface and the density of the liquid phase change. To account for the variation in liquid density, an equation fit to the experimental density data is included in the transport model. To track the moving interface, the volume-of-fluid method is used. The diffusivities at dilute concentration and at thermodynamic phase equilibrium are determined and compared with the literature values and those obtained from correlations.     

Broadband complex dielectric constants of water and sodium chloride aqueous solutions with different DC conductivities

Broadband dielectric constant measurements in the frequency range between 40 Hz and 50 GHz of pure water, tap water, and sodium chloride aqueous solutions with different DC conductivities up to 5 S/m were conducted. The measurements were done using an impedance analyzer for the frequency range 40 Hz to 110 MHz and a vector network analyzer for 10 MHz to 50 GHz. The results show that the dielectric constant decreases with the increase in DC conductivity and is dependent on the frequency. The dielectric relaxation of water with a constant dielectric loss peak was also observed. The frequency dependence of the conductivity is also large. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Microwave absorption properties of (1 − x)La0.85Ag0.15MnO3/x graphene (x = 0, 3, and 5 wt.%) composites

Composite of (1 − x)La_0.85Ag_0.15MnO₃/x graphene (x = 0, 3, and 5 wt.%) and epoxy resin with a ratio of 4:1 were prepared to investigate the influence of the addition of graphene in (1 − x)La_0.85Ag_0.15MnO₃/x graphene on real and imaginary parts of permittivity, permeability, as well as microwave reflection loss (RL), using a vector network analyzer in the 8–18 GHz of the frequency range. It is found that the value of RL is smaller at x = 3 wt.% (−20.74 dB at 14.85 GHz) and 5 wt.% (−14.81 at 16.50 GHz) compared to at x = 0 wt.% (−8.89 dB at 15.90 GHz). The result indicates that microwave absorption properties significantly improved as a result of the addition of graphene. It is suggested that the addition of graphene enhanced the dielectric loss–related mechanism such as interfacial polarization and conduction loss resulting in an improvement of microwave absorption performance for both x = 3 wt.% and x = 5 wt.% samples. It also shows that the observed enhanced microwave absorption properties may also be influenced by the resistivity of the sample as x = 3 wt.% sample exhibits enhanced microwave absorption properties and the lowest resistivity among the studied samples.     

Syngas Production via Bi-Reforming of Methane Over Fibrous KCC-1 Stabilized Ni Catalyst

Topics in Catalysis - Bi-reforming of methane (BRM) technology has the potential to serve as an alternative energy source while also mitigating greenhouse gas emissions. However, the main hurdle in...     

Symmetric and asymmetric impacts of the palm oil industry on carbon dioxide emissions in Malaysia based on linear and nonlinear autoregressive distributed lag models

Clean Technologies and Environmental Policy - Palm oil is a major global commodity that is vital for the well-being of many communities. Despite its significant contribution to the attainment of...     

Production of N-methyldiethanolamine di-ester via heterogeneous transesterification of palm methyl ester over modified calcium oxide catalyst by metal oxides

The production cycle of the heterogeneous catalyzed-transesterification of methyl ester and alkanolamine for the production of esterquats precursor can be considered as a cleaner and sustainable process. This process is an important alternative route as opposed to the conventional homogeneous catalysis as it can eliminates the formation of wastewater, consumes less toxic chemical and reduce the production cost through catalyst reuse. Calcium oxide (CaO)-based catalysts which include pure CaO and modified CaO by other metal oxides were employed in this study for the production of alkanolamine ester, a precursor of esterquats. The basicity and textural properties of these catalysts were characterized using TPD-CO₂ and N₂ physisorption, respectively. Transesterification activity of CaO-based catalysts successfully showed a high di-ester yield of more than 85% at 160°C, 80 mbar, 4 wt% of catalyst dosage, 6 h reaction time, methyl palmitate to N-methyldiethanolamine mole ratio of 2:1 and agitation speed of 150 rpm. ZnO/CaO catalyst rendered the best durability characteristic as it exhibited constant activities for three subsequent runs with 85% di-ester yield. ZnO/CaO showed high catalytic activity similar to pure CaO catalyst with low leaching of Ca active phase and better reusability than that of pure CaO catalyst, that shows loss of its activity after the first cycle.     

Comparison of high pressure and thermal pasteurization on the quality parameters of strawberry products: a review

Food Science and Biotechnology - Strawberry (Fragaria ananassa) is rich in bioactive compounds with high antioxidant activity. High pressure processing (HPP) is an efficient alternative to preserve...