Study on the performance enhancement of biomedical implants: in vitro test under UV irradiation of titanium anodised in mixed electrolyte

Titanium (Ti) recently has widely been used in the biomedical applications due to its high performance. Therefore, surface modifications of titanium have attracted a lot of interest to provide better osseointegration. Ti was subjected to anodic oxidation process and in vitro testing to assess the bioactivity of titanium oxide (TiO2) coating. TiO2 coating has been anodised at room temperature in different electrolyte; in sulphuric acid (H2SO4); phosphoric acid (H3PO4); and a mixture of H2SO4 and H3PO4 acids. The parameters used in anodization were: concentration of the electrolytes, applied voltage and current density. The coated surface is then evaluated using different testing techniques; the microstructure using scanning electron microscope (SEM); the elemental analysis using Energy-dispersive x-ray spectroscopy (EDX); mineralogical and crystal structure using x-ray diffraction (XRD); absorption analysis using Fourier transform infrared spectroscopy (FT-IR); and the hydrophilicity using water contact angle (WCA). TiO2 was then subjected in vitro testing to assess the bioactivity of TiO2 surface; that is the apatite formation ability. The apatite formation of the TiO2 coating was precipitated by using simulated body fluid (SBF) in the dark and under the ultraviolet (UV) irradiation to mimic the reactions that may occur with the human bone-like cells layer. The testing was done to evaluate the apatite’s microstructure, mineralogy, elements and absorption. From the results it was found that higher apatite was obtained with the increased of the immersion time; higher apatite formation and crystallization was found at earlier time of immersion for the TiO2 that was immersed in SBF under the UV; higher apatite was obtained on the TiO2 coatings that were anodised in H2SO4, H3PO4 and mixture electrolyte at lower electrolyte concentration. The increased apatite on these coatings can be related to the strong Ti-O- functional groups on the coating surface. The highest apatite was obtained on the TiO2 coating that was anodised in a mixture electrolyte that has obtained Ti-OH functional group. The UV has resulted in the increased Ti-O- and Ti-OH groups, thus higher apatite precipitation ability

Impact of Near Well Heterogeneity on Conformance

Imperial Users onl

Culture, Wasta and perceptions of performance appraisal in Saudi Arabia

This article explores the relationship between Arabic culture and employees’ perceptions of performance appraisal in a Saudi Arabian company named SACO. Using an interpretive and qualitative methodological framework, the article suggests that Western models of performance appraisal rooted in rationality and objectivity conflict with aspects of Saudi Arabian culture. Specifically, the personal relations implicated in the social practice of Wasta. However, the article also shows how SACO employees are beginning to reject Saudi Arabian cultural norms and adopt alternative values which are linked to notions of organisational justice and individual egalitarianism. These values are compatible with Western models of performance appraisal

An improved firefly algorithm for optimal microgrid operation with renewable energy

Lately, an electrical network in microgrid system becomes very important to rural or remote areas without connection from primary power grid system. Higher cost of fuels, logistic, spare parts and maintenance affect the cost for operation microgrid generation to supply electrical power for remote areas and rural community. This project proposes an Improved Firefly Algorithm (IFA), which is a improvement of classical Firefly Algorithm (FA) technique using characteristic approach of Lévy flights to solve the optimal microgrid operation. The IFA has been used for optimizing the cost of power generation in microgrid system where daily power balance constraints and generation limits are considered. The microgrid system for this case study considered both of renewable energy plant and conventional generator units. There are two test systems that have been considered as case study. The first test system is a simple microgrid system which consists of three generators. The second test system consists of seven generating units including two wind turbines, three fuel-cell plants and two diesel generators. The IFA method has been implemented using MATLAB software. The results obtained by IFA was compared to FA and other algorithms based on optimal cost, convergence characteristics and robustness to validate the effectiveness of the IFA. It shows that the IFA obtained better results in terms of operating costs compared to FA, Differential Evolution (DE), Particle Swarm Optimization (PSO) and Cuckoo Search Algorithm (CSA)

Effects of flux application and melting parameters in investment casting of pure aluminium by in-situ melting technique

Investment cast aluminium suffers porosity defect attributed to the complex combination of various factors including melt quality, casting process parameter and pouring technique. Even though, melt treatment and controlled of the process parameter have promising result, however turbulence developed during pouring of molten aluminium increasing the formation of porosity as a result of the entrainment of the surface oxide (Al2O3) film known as bifilm. Currently, turbulence free filling system was applied in casting process using tilt casting, bottom filling integrated with low pressure and also in-situ casting or in-situ melting techniques to address the porosity problem. However, in-situ melting technique has not been studied to reduce the porosity of the investment cast aluminium due to the oxidation of the granular aluminium occurs during heating hinders the complete melting of the granules. This research develops a procedure for investment casting of aluminium granules of 99.4% purity by in-situ melting technique. The aluminium granules were filled in ceramic moulds and heated at four different temperatures of 700, 750, 800 and 850oC for 30 and 60 min in a high temperature muffle furnace in ambient. As the heating temperature and duration were increased, the aluminium granules incompletely melt and produced a casting, however the granules agglomerate and replicate the shape of the ceramic mould. The aluminium granules oxidised during heating, encapsulated by a layer of complex oxides composed of stable [α-Al2O3], metastable [γ-Al2O3] and hydroxides. The thickness of the oxide layer formed on the surface of the air-heated granules increased as the heating temperature and duration were increased. The aluminium granules then were heated at the temperature of 850oC for 30 min in argon environment at the flow rate of argon gas 0.5, 2.5 and 5 l/min to reduce the oxidation of the aluminium granules. The thickness of the oxide layer formed on the argon-heated granule (5 l/min) was reduced by 60%, but failed to produce a casting. NaCl-KCl flux was applied, which was mixed and sprinkled on the aluminium granules at the Al:Flux ratio of 1:0.2, 1:0.25 and 1:0.33 and heated at the temperature of 850oC for 30 min to break the oxide layer that encapsulate the granules during heating. At the Al:Flux ratio of 1:0.33, 99% of the aluminium granules were successfully melted and produced a casting. The granules began melting at the temperature range 657.2 to 658.4oC and completely melted in 16 min with final melting temperature between 660.1 and 660.6oC. The average porosity level of the casting was 1.22%, which is lower than the investment cast aluminium produced by current pouring technique (2.48%). The low porosity level was attributed to micro-intergranular porosity present in the casting due to volume shrinkage. Investment casting of aluminium granules by in-situ melting technique with application of NaCl-KCl flux at the Al:Flux ratio of 1:0.33 mixed and sprinkled on the granules heated at the temperature of 850oC for 30 min producing low porosity aluminium casting

Answering Global Warming’s Hottest Debate: A Better Way to Tax Carbon

Some of you are sick of hearing about it, some of you don’t really care, and the rest of you are probably the reason the first group is sick of hearing about it, but regardless of which category you fall into, one thing is certain: climate change is real and it’s already happening. With that said, I’m moving forward under the assumption that all of us here believe in science and understand this phenomenon to be largely a result of post-industrial anthropogenic activity. In which case, reducing our emissions is the only way to prevent climate change from becoming a global catastrophe. Enter the IRS’s Section 45Q tax code, the best solution you’ve never heard of for reducing carbon emissions. Alright, so what is Section 45Q and why is it so great? Long story short, 45Q is a performance-based tax credit being legislated by the IRS to incentivize the construction and operation of carbon capture & sequestration (“CCS”) projects by large industrial polluters. To clarify, this is different than a pure “carbon tax,” where polluters are forced to pay for their emissions. Instead, this tax credit provides economic reward to firms who successfully implement CCS projects. Without getting overly technical, Section 45Q will work by granting eligible firms a tradeable tax credit for each metric ton of carbon they successfully capture and sequester (securely store underground) with their CCS equipment. However, many of the firms eligible for these tax credits have limited tax appetite (taxable income) and are unable to efficiently utilize all the credits they earn. This creates a market where institutional investors can get involved, because firms with CCS projects will turn to investors for cash in return for future discounted tax credits to develop projects—a proven concept derived from the PTCs and ITCs I describe later. As a result, projects get structured in a mutually beneficial manner and the CCS industry gets access to a substantially larger pool of capital. The involvement of institutional investors is important because their additional capital will foster the development of country-wide CCS infrastructure, similar to what we’ve seen happen with wind and solar in recent years. Switching from fossil fuels to renewables won’t be enough to curb GHGs, which is why reducing emissions in existing industries is critical. However, without these tax credits, implementing a CCS project would yield significant economic loss to developers, so Section 45Q is essential to reaching a point of wide-scale commercial operation. Referencing my earlier comment, this tax credit structure has already proven extremely successful in accelerating the adoption of new and expensive technologies. Consider the results Production Tax Credits (“PTCs”) and Investment Tax Credits (“ITCs”) have generated for wind and solar power. Since ITCs were enacted in 2006, the U.S. solar industry has grown by more than 10,000%, creating hundreds of thousands of new jobs and stimulating the investment of billions of dollars into our economy . Similarly, since 2007, PTCs helped generate over $143 Billion of private investments in our economy to support wind energy, quadrupling the country’s wind power capacity, creating over 114,000 new jobs, and reducing the cost of U.S. wind power by nearly 70% . I firmly believe carbon tax credits will do the same for CCS. Nevertheless, detractors of Section 45Q persist. Many opponents of Section 45Q argue it is counterproductive to subsidize the industries causing much of our country’s emissions in the first place, ultimately slowing our transition off fossil fuels. In reality, many eligible industries—like cement manufacturing—emit even larger amounts of carbon than power plants and would continue operating long after a full transition to low-carbon fuels. Furthermore, some industries will become carbon negative by implementing CCS. For example, the CO2 released from ethanol refineries during fermentation is the same carbon plants absorbed from the atmosphere during photosynthesis. Therefore, sequestering these emissions reduces atmospheric carbon, something even wind and solar can’t do. Other opponents of 45Q worry firms will earn credits for emissions they didn’t truly mitigate. Although, if a CCS project shows even the slightest risk of having its credits recaptured by the IRS for improper mitigation, institutional investors will deem it too risky and withhold the capital necessary for the project to begin. Granted, Section 45Q isn’t the perfect answer, but it is the better answer to a carbon tax, one that helps firms reduce emissions without punishing them, and follows a proven method for fostering the development of new industries while benefitting the economy. I stand behind the implementation of CCS subsidies and urge you to do the same

Kesedaran terhadap amalan pemakanan seimbang dalam kalangan pelajar Politeknik Merlimau, Melaka: satu tinjauan

Pemakanan yang baik mula mempengaruhi kesihatan tubuh badan sejak daripada kecil lagi. Pemakanan memainkan peranan penting dalam mengekalkan kesihatan dan mencegah penyakit. Oleh itu, kajian ini dilakukan adalah bertujuan untuk meninjau sejauhmanakah kesedaran pelajar politeknik terhadap amalan pemakanan seimbang. Skop yang dikaji dalam kajian ini ialah menentukan tahap pengetahuan pelajar terhadap pemakanan seimbang, meninjau faktor-faktor yang mempengaruhi pemilihan pemakanan pelajar, menentukan tahap kesedaran pelajar terhadap amalan pemakanan seimbang serta mengenalpasti hubungan yang signifikan di antara tahap pengetahuan dengan amalan pemakanan seimbang. Reka bentuk kajian yang digunakan penyelidik adalah kajian deskriptif berbentuk tinjauan. Saiz sampel seramai 297 orang responden telah terlibat dalam kajian ini melibatkan Politeknik Merlimau, Melaka dari semua jabatan. Instrumen yang digunakan dalam kajian ini adalah borang soal selidik. Data dalam kajian ini dianalisis dengan menggunakan perisian Statistical Package For Social Science (SPSS) versi 21.0 bagi mendapatkan nilai skor min, kekerapan, sisihan piawai, peratusan (%) serta Ujian Korelasi Pearson kerana data bertaburan normal. Hasil analisis menunjukkan bahawa tahap pengetahuan pelajar terhadap pemakanan seimbang masih di peringkat sederhana. Selain itu, melalui kajian ini dapat dibuktikan bahawa harga makanan dan keluarga merupakan faktor utama yang mempengaruhi pemilihan makanan pelajar. Walaupun tahap pengetahuan mereka sederhana, akan tetapi kesedaran mereka terhadap amalan pemakanan seimbang tinggi. Melalui analisis ujian korelasi Pearson mendapati bahawa terdapat hubungan yang signifikan di antara tahap pengetahuan pelajar dengan amalan pemakanan mereka. Walaupun sedemikian, perhubungan yang wujud adalah pada tahap sederhana dan positif. Kata kunci : Pemakanan seimbang, pengetahuan, amalan pemakanan seimbang, kesedaran