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Low pressure spark plasma sintered hydroxyapatite and Bioglass® composite scaffolds for bone tissue repair
No full textHydroxyapatite (HA) based composite scaffold materials were prepared by combining it with Bioglass® (BG) to overcome the major limitations of HA such as the lack of osseointegration, inadequate bioactivity and biodegradation. Earlier attempts to prepare BG reinforced HA composites via the conventional sintering process resulted excessive reactions between the constituents and/or crystallization of BG. Excessive reaction between the constituents and crystallization of BG are known to lengthen the bioactivity response. In this work, low pressure spark plasma sintering (SPS) was utilized to prepare HA-BG composite scaffold materials with BG content until 30 wt%. Compared to the conventional sintering practice, the milder processing conditions during the SPS process such as the compaction pressure, sintering time and temperature produced HA-BG composite scaffolds without the excessive reactions between the constituents and prevented the crystallization of BG. All of the developed composites were composed of calcium phosphate (HA and β-Tricalcium Phosphate phases) and glassy phases only. The effect of BG addition on the physical properties such as the bulk density, relative density and hardness are well in line with the XRD and FESEM analyses. The in vitro bioactivity investigation from the immersion of samples in simulated body fluid (SBF) confirmed the improved bioactivity of the composite samples with increased BG content
Experimental evaluation of fatty acid composition influence on Jatropha biodiesel physicochemical properties
No full textThe physiochemical properties of biodiesel are significantly influenced by its fatty acid composition (FAC). This research investigates FAC of Jatropha biodiesel (JB) synthesized using feedstocks originated from the east (JBEM) and west (JBWM) Malaysian regions together with biofuel properties. The critical properties of pure biodiesels and blends were analysed according to ASTM D6751/EN 14214 standards. The JB properties were precisely regulated by its FAC features such as saturated fatty acids (SFAs), unsaturated fatty acids (USFAs), degree of unsaturation, and long chain saturated factor. The influence of SFA and USFA was inversely associated over biodiesel properties. The presence of higher SFA greatly affects biodiesel properties like the cetane number, cold filter plugging point, kinematic viscosity, density, cloud point, and pour point; conversely, the fuel properties such as oxidation stability, iodine value, acid value, water content, and flash point were improving with USFA contents. Blending of biofuels with petro diesels considerably improved their fuel properties
Climate change and sustainable development issues: arguments and policy initiatives
No full textGlobal warming has emerged as one of the most serious threats to the existence of humankind. There is also increasing acknowledgement that old arguments that focused on the exhaustion of economic resources and changing dynamics of utility are no longer necessary and useful in confronting climate change. This article reviews the main arguments that have shaped recent global initiatives on mitigating climate change and global warming. The increasing introduction of climate change mitigation initiatives comes from the recognition that such initiatives no longer require reducing economic growth. Fortunately, recent developments appear promising as the majority of the world's nations pledged at the Paris Accord of 2015 to check environmental degradation. Consequently, individual signatories have supplied intended national determined contribution proposals to the United Nations Framework Convention for Climate Change to cap temperature rise to 1.5 ˚C over the next century
Empirical solutions for stress intensity factors of a surface crack in a solid cylinder under pure torsion
No full textNo empirical solution for the stress intensity factors (SIFs) of a surface crack in a solid cylinder under torsion was reported in literature. In this paper, empirical solutions for Modes I, II, and III stress intensity factors of a semi-elliptical surface crack in a solid cylinder under pure torsion are proposed. The dual boundary element method (DBEM) based software was used to generate the SIFs for different crack size, crack aspect ratio, and different inclination angles. Next, the solutions for the SIFs were produced through a systematic curve fitting approach
Academic stress among university students: A quantitative study of generation Y and Z’s perception
No full textConcerns on academic-related stress among students in institutions of higher learning are widespread. Pursuing tertiary education is said to be stressful as students pass through the process of adapting to new educational and social environments. Past literature has highlighted that common academic stressors include family-related pressures, scholarship requirements, financial burdens, competition in class and course-related stress. These stressors trigger physical and psychological issues resulting in lack of energy, loss of appetite, headaches, sleep problems or gastrointestinal problems. Although studies have been done on common stressors in universities/colleges, perceptions of what are considered academic stressors from the Generation Y and Z perspectives using the Perceived Stress Test (PSS) have not been carried out in the Malaysian context. Thus, this quantitative study aims to identify the perceptions of Gen Y and Z (18-25 years old) students to identify factors attributing to stress and their effects. The findings show that 88% of the respondents confirmed that studies are the main cause of their stress, while 78% admitted facing a moderate stress level and out of this, 36% had BMI that fell in the overweight/ obese category. Further, the study indicates that 54% experienced sleeping disorders. It is hoped that the findings will add to the understanding of the stress levels among Generation Y and Z to enable policy-makers and university/college management teams to strategise actions to alleviate issues arising from academic stress among students
The Malayan Indian Congress and Early Political Rivalry among Indian Organisations in Malaya, 1946–1950
No full textThe Malayan Indian Congress (MIC) emerged amid the chaos of the immediate postwar period in Malaya to represent the interests of the minority Indian community. Several Indian leaders who had been involved in the Indian Independence League during the war decided that a national organisation was needed to serve as the voice of the Indian community. Within a few years, the party became the leading representative of the Indian community. But the MIC's transformation was not without serious challenges from within and from other Indian political movements. This article examines the early period of the party's history to trace the growth of the MIC into the leading political movement of the Indians in Malaya, its internal problems and significant rivalry with other Indian-based organisations during this period and the issues that arose. The article shows that a pragmatic approach by the party leadership, in particular its discontinuance of the boycott of the 1948 Federation Constitution and its principled position on citizenship, enabled the party to overcome the challenge posed by rival Indian organisations to become the leading voice of the Indians by 1950
Optimal fixed charge–rate coordination of plug-in electric vehicle incorporating capacitor and OLTC switching to minimize power loss and voltage deviation
No full textIntegration of plug-in electric vehicles (PEVs) in a smart grid largely deteriorates the performances of the system. This paper proposes a two-stage optimization approach to optimize customer satisfaction as well as grid performances when fixed charge–rate PEV coordination, switching capacitor and on-load tap charger (OLTC) are coordinated simultaneously. To coordinate PEV charging, capacitor and OLTC, an efficient binary particle swarm optimization (BPSO) has been applied. The main consideration in this optimal coordination is to minimize the daily power loss and voltage deviation while maximizing customer satisfaction. Simulation results are compared with the variable charge–rate coordination that is proposed previously
Ultrashort Pulse Soliton Fiber Laser Generation With Integration of Antimony Film Saturable Absorber
No full textA soliton-locked Erbium-doped fiber laser is demonstrated for the first time using a pure Antimony (Sb) film as a saturable absorber (SA). The SA device is fabricated by depositing a 5 μm Sb layer onto a polyvinyl alcohol thin film via Physical vapor deposition process. Self-starting soliton mode-locked pulses train with a constant repetition rate of 0.99 MHz is obtained as the pump power increased from 101 mW to 142 mW. The laser operates at 1559 nm with a pulse width of 3.53 ps. At the pump power of 142 mW, the maximum peak power and pulse energy are calculated as 5.83 kW and 20.59 nJ, respectively. The obtainable pulse is very stable with a signal-to-noise ratio (SNR) of 70 dB. Our experimental results manifest that the pure Sb thin film-based SA is able to generate mode-locked pulsed laser at the 1.55-micron laser regime
From immigrants to sports figures: The case study of the ioc refugee team in Rio Olympics 2016
No full textThis paper examines the experiences of refugee athletes in pursuing their ultimate dream to compete in the Olympics, and explores the challenges and prospects they faced. Relevant data were obtained from secondary sources, such as sports articles and biographies on websites, about refugee athletes competing in the Rio Olympics in 2016. Eleven sports personalities among the refugees from South Sudan, Syria, Democratic Republic of Congo and Ethiopia were studied. They represented the Refugee Team in judo, athletics and swimming. A summative content analysis was conducted to see variations in their sporting motives. The analysis suggests that despite of harsh living conditions in their home countries, refugees’ passion to compete in sport was very much alive when they arrived at the host countries. The paper also reveals that host countries like Germany, Brazil, and Luxembourg provided several opportunities for the refugees to venture into sport, but available opportunities are selective due to their status as refugees. Also, their participation in sport is confined to Olympic events only. Today, participation in sport is seen as an avenue for refugees to salvage their pride and dignity apart from seeking better opportunities in life. Indeed, sport is a powerful tool to unite people from different backgrounds and nationalities
Not-yet-designed multilayer Nb/HA/MWCNT-Au/Se/AuNPs and NbO2/HA/GO/Se biocomposites coated Ti6Al7Nb implant
No full textIncreased commercial demands of appropriate bone materials, smart multilayer biocomposites named niobium/hydroxyapatite/multiwall carbon nanotube hybrid gold/selenium/gold nanoparticles (Nb/HA/MWCNT-Au/Se/AuNPs) and niobium oxide/hydroxyapatite/graphene oxide/selenium (NbO2/HA/GO/Se) support Ti-6Al-7Nb implant alloy (Ti67IMP). Adhesion strength of primary as-deposited films was assessed by micro-scratch nanomaterial analysis. The microstructure, phase and elemental features of developed large-surface-area composites were characterized via FESEM, TEM/HRTEM, XPS, XRD/GIXRD, Raman and FT-IR techniques. Besides, in-vitro bioactivity study of reinforced Ti67IMP in simulated body fluid (SBF) media followed to evaluate the enhanced potential of bone-like apatite layer formation on treated surfaces comparatively. The designed multilayer biofilm-Ti67IMP systems may contribute to facilitate low-risk bone regeneration with antibacterial and drug delivery potential and long-term mechanical satisfaction