The availability of daylight from tropical skies—a case study of Malaysia

In Malaysia, no long-term daylight data are measured. It was only recently that the need to measure the availability of daylight became urgent when the importance of daylighting in buildings was rediscovered. The hourly daylight availability has been simulated for the Malaysian sky using daylight modelling techniques based on empirical and measured solar irradiation and cloud cover data. This paper presents the techniques involved in producing exterior illuminance data. These data were then compared with measured illuminance at Shah Alam and Bangi, Malaysia. The global illuminance levels are generally high, with values exceeding 80,000 lux at noon during the months when solar irradiation is highest. Even during the months when the ground receives less solar irradiation, the peak illuminance can reach 60,000 lux. Applications and uses of such data are in daylighting design, both for visual and thermal comfort, task illuminance and energy-conscious design of buildings. Recommendations are made at the end of the paper on the various climatic data that are required to be measured for overall daylighting design applications.     

Comparative study of chelating ion exchange resins for the recovery of nickel and cobalt from laterite leach tailings

Commercially available chelating resins with the iminodiacetate functional group have been evaluated for their suitability for the adsorption of nickel and other metal ions by a resin-in-pulp process from the tailings of a pressure acid leach process for nickel laterites. The Amberlite IRC 748 and TP 207 MonoPlus resins were found to be the most suitable in terms of loading capacity for nickel and kinetics of adsorption. The resin with the highest nominal capacity was observed to adsorb less nickel as a result of the adsorption of greater amounts of the impurity ions. The equilibrium loading for nickel on the preferred resin was found to be similar from the ammonium and protonated form of the resin although the kinetics of adsorption is greater when the resin is initially in the ammonium form. A study of the kinetics of the loading of nickel and cobalt from pulp has shown that the rate can be described in terms of a first-order approach to equilibrium. The optimum pH for adsorption was found to be in the range 4 to 5 as this pH is high enough to maximize the adsorption of nickel and cobalt while preventing precipitation of nickel and cobalt as hydroxides from the pulp. A method for minimizing the competition from more strongly loaded ions such as iron(III) and chromium(III) which are present in the pulp was also developed in the initial laboratory phase of the study.     

Formulation Optimization of a Palm-Based Nanoemulsion System Containing Levodopa

Response surface methodology (RSM) was utilized to investigate the influence of the main emulsion composition; mixture of palm and medium-chain triglyceride (MCT) oil (6%–12% w/w), lecithin (1%–3% w/w), and Cremophor EL (0.5%–1.5% w/w) as well as the preparation method; addition rate (2–20 mL/min), on the physicochemical properties of palm-based nanoemulsions. The response variables were the three main emulsion properties; particle size, zeta potential and polydispersity index. Optimization of the four independent variables was carried out to obtain an optimum level palm-based nanoemulsion with desirable characteristics. The response surface analysis showed that the variation in the three responses could be depicted as a quadratic function of the main composition of the emulsion and the preparation method. The experimental data could be fitted sufficiently well into a second-order polynomial model. The optimized formulation was stable for six months at 4 °C.     

Facile modification of polysulfone hollow-fiber membranes via the incorporation of well-dispersed iron oxide nanoparticles for protein purification

Protein existence in wastewater is an important issue in wastewater management because proteins are generally present as contaminants and foulants. Hence, in this study, we focused on designing a polysulfone (PSf) hollow-fiber membrane embedded with hydrophilic iron oxide nanoparticles (IONPs) for protein purification by means of ultrafiltration. Before membrane fabrication, the dispersion stability of the IONPs was enhanced by the addition of a stabilizer, namely, citric acid (CA). Next, PSf–IONP–CA nanocomposite hollow-fiber membranes were prepared via a dry–wet spinning process and then characterized in terms of their hydrophilicity and morphology. Ultrafiltration and adsorption experiments were then conducted with bovine serum albumin as a model protein. The results that an IONP/CA weight ratio of 1:20 contributed to the most stable IONP dispersion. It was also revealed that the membrane incorporated with IONP–CA at a weight ratio of 1:20 exhibited the highest pure water permeability (58.6 L m⁻² h⁻¹ bar⁻¹) and protein rejection (98.5%) while maintaining a low protein adsorption (3.3 μg/cm²). The addition of well-dispersed IONPs enhanced the separation features of the PSf hollow-fiber membrane for protein purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47502.     

Photodetector performance enhancement using an electron accelerator controlled by light

A new method of photodetector performance enhancement using an embedded optical accelerator circuit within the photodetector is proposed. The principle of optical tweezer generation using a light pulse within a PANDA ring is also reviewed. By using a modified add-drop optical filter known as a PANDA microring resonator, which is embedded within the photodetector circuit, the device performance can be improved by using an electron injection technique, in which electrons can be trapped by optical tweezers generated by a PANDA ring resonator. Finally, electrons can move faster within the device via the optical waveguide without trapping center in the silicon bulk to the contact, in which the increase in photodetector current is seen. Simulation results obtained have shown that the device's light currents are increased by the order of four, and the switching time is increased by the order of five. This technique can be used for better photodetector performance and other semiconductor applications in the future.     

Effect of Mg, Si and Cu content on the microstructure of dilute 6000 series aluminium alloys

The effect of Mg, Si and Cu content on the microstructural development during ageing treatment of dilute 6000 series alloys have been investigated using transmission electron microscopy (TEM). Four dilute alloys were used in this study. These alloys were subjected to quenching and artificial ageing at 100 °C, 185 °C and 300 °C. The microstructural developments of the precipitates formed were monitored by TEM. The ageing temperature of 100 °C was found to be too low to form precipitates. It was found that needle or rod-shaped precipitates were formed in the alloys after ageing at 185 and 300 °C. Prolong ageing up to 1000 h at 300 °C resulted in the formation of Mg₂Si precipitate that coexists with the type of AlFeSi and Si precipitates. The results show a correlation between the Mg₂Si, Si and Cu content on the microstructure of the four dilute alloys after ageing treatment.     

5–11 GHz CMOS PA with 158.9 ± 41 ps group delay and low power using current-reused technique

This paper proposes the design of a low group delay and low power ultra-wideband (UWB) power amplifier (PA) in 0.18 μm CMOS technology. The PA design employs two stages cascade with inductive peaking technique to provide broad bandwidth characteristic and higher gain while gain flatness can be achieved by connecting inter-stage circuit. A common gate current-reused technique is adopted at the first stage amplifier to achieve good input matching, low group delay and low power. The simulation results show that the proposed PA design has an average gain of 11.5 dB with flatness of ±0.4 dB from 5–11 GHz, while maintaining bandwidth of 4.2–12.3 GHz. An input return loss (S₁₁) less than −10.4 dB and output return loss (S₂₂) less than −9.5 dB, respectively are obtained. The PA design achieves excellent phase linearity (i.e., group delay variation) of ±41 ps and only consuming 17 mW power from 1.2 V supply voltage. A good output 1-dB compression point OP1 dB of 3.7 dBm is obtained. By using this method, the proposed design has low group delay variation and lowest power among the recently reported UWB CMOS PAs applications.     

Effect of Ice Storage on Fatty Acids Profile of Freshwater and Marine Fishes Available at Malaysia Wet Market

This study was conducted in the intention to identify and determine the fatty acid profile in freshwater fishes and marine fishes available at Malaysian wet market as well as its deterioration kept in ice storage up to 21 days. Three freshwater fishes： Oreochromis sp. commonly known as Tilapia, Monopterus alba commonly known as Belut, Pangasius hypothalamus commonly known as Patin and marine fish Rastrellinger kanagurta commonly known as Kembung, Thunnus tonggol commonly known as Tongkol and Epinephelus sp. commonly known as Kerapu with average weight of 500-600 g were tested with storage time of 1, 3, 6, 9, 12, 15. 18 and 21 days kept ice storage. The Fatty Acid Methyl Ester （FAMEs） were prepared using one step method and were identified by using gas chromatograph Agilent 6890N equipped with flame ionization detector. Separation was performed by injecting 1μL of a sample into the capillary column DB-225MS column （30 m length × 0.250 mm diameter × 0.25 μm film thickness）. The fatty acids peaks were indentified using Agilent Technologies software 5988-5871EN and comparing their retention time against the authentic standard Supelco 37 Component FAME Mix. Statistical results showed that palmitic acid （CI6：0） were the major fatty acids among the saturated fatty acids （SFA） while oleic acid （C 18：1 n9） were the major monounsaturated fatty acids （MUFA） detected in each sample studied. Both linoliec acid （C 18：2n6） and arachadonic acid （C20：4n6） were predominant in total omega-6 polyunsaturated fatty acids （PUFA）. The essential fatty acids show prominent in ecosapentanoic acid （C20：5n3） and docosahexanoic acid （C22：6n3）. During ice storage polyunsaturated fatty acids （PUFA） and monounsaturated fatty acids （MUFA） decrease as the time of storage increase. There is significant decrease in polyene index （PI） index of all the species throughout the storage time, The PI in freshwater fishes decrease by 70% in Tilapia, 90.1% in Belut and 90.9% in Patin, while for marine fishes, PI in Kembung decreases by 67.8%, 85.7% in Kerapu and 65.93% in Tongkol during kept in ice storage. During ice storage, the percentage of EPA, DHA and ALA decrease in Tilapia （55.36%, 13.86% and 75.41%）, Belut （78.55%, 87.74 % and 74.53%） and Patin （82.45%, 40.0% and 82.10%）, respectively. The same result were also observed in the marine fishes where the percentage ofEPA, DHA and ALA decrease in Kembung （94.27%, 49.03% and 88.52%）, in Kerapu （73.03%, 88.18% and 38.73%） and Tongkol （70.05%, 38.24% and 57.14%）, respectively.