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PublicationEffects of multiple reflow on the formation of primary crystals in Sn-3.5Ag and solder joint strength: experimental and finite element analysis(MDPI, 2023)The growth and formation of primary intermetallics formed in Sn-3.5Ag soldered on copper organic solderability preservative (Cu-OSP) and electroless nickel immersion gold (ENIG) surface finish after multiple reflows were systematically investigated. Real-time synchrotron imaging was used to investigate the microstructure, focusing on the in situ growth behavior of primary intermetallics during the solid–liquid–solid interactions. The high-speed shear test was conducted to observe the correlation of microstructure formation to the solder joint strength. Subsequently, the experimental results were correlated with the numerical Finite Element (FE) modeling using ANSYS software to investigate the effects of primary intermetallics on the reliability of solder joints. In the Sn-3.5Ag/Cu-OSP solder joint, the well-known Cu6Sn5 interfacial intermetallic compounds (IMCs) layer was observed in each reflow, where the thickness of the IMC layer increases with an increasing number of reflows due to the Cu diffusion from the substrate. Meanwhile, for the Sn-3.5Ag/ENIG solder joints, the Ni3Sn4 interfacial IMC layer was formed first, followed by the (Cu, Ni)6Sn5 IMC layer, where the formation was detected after five cycles of reflow. The results obtained from real-time imaging prove that the Ni layer from the ENIG surface finish possessed an effective barrier to suppress and control the Cu dissolution from the substrates, as there is no sizeable primary phase observed up to four cycles of reflow. Thus, this resulted in a thinner IMC layer and smaller primary intermetallics, producing a stronger solder joint for Sn-3.5Ag/ENIG even after the repeated reflow process relative to the Sn-3.5Ag/Cu-OSP joints.
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PublicationInsights on anticancer activities, associated Phytochemicals and potential molecular mechanisms of Quisqualis indica: a mini review(Universiti Kebangsaan Malaysia (UKM), 2023)Drug resistance is the main issue causing the treatment failure of anticancer drugs. This issue has urged researchers to search for new substances from medicinal plants, which are widely reported as the good sources of anticancer agents. Quisqualis indica is a plant belongs to Combretaceae family, known as Rangoon Creeper, which can be found abundantly in tropical countries and distributed profusely as a wild shrub. It has been widely used traditionally and scientifically claimed to process various therapeutic activities. It has recently been reported to possess various potential anticancer activities against different cancers. Looking at its availability in almost all seasons and grow fast, it is an arising source of herbal medicine in the discovery of anticancer drugs economically. Besides, Q. indica is enriched with several secondary metabolites of interest, which are responsible for the positive findings for its anticancer potentials. In this review, we aim to decipher and discuss the anticancer activities of Q. indica crude extracts and isolated phytochemicals as evidenced in preclinical models, as well as the associated molecular mechanisms. More preclinical investigations on its anticancer potentials should be conducted before translation to clinical testing.
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PublicationBiological synthesis of zinc-oxide nanoparticle using wide-spread Lentinus sajor-caju extract as a carrier for natural-compounds(Elsevier, 2023)The use of nanotechnology in industry and medicine has recently become a hot topic of research. This study focused on synthesizing zinc oxide nanoparticles (ZnONPs) using Lentinus sajor-caju extract, followed by applying the nanoparticle as a carrier for natural compounds. Energy dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Field-emission scanning electron microscopy (FESEM), Filed-emission transmission electron microscopy (FETEM), and zeta potential measurements were used to characterize the synthesized nanoparticles. The synthesis of ZnONPs was also confirmed by UV–visible spectroscopy. The ZnONPs had a spherical shape with an average size of 28 nm in diameter, according to FETEM and FESEM. X-ray powder diffraction and selected area electron diffraction showed that the ZnONPs were crystalline in structure. The active components of the L. sajor-caju extracts were found to cap the ZnONPs, according to FTIR analysis. Additionally, EDX analysis revealed test showed the elemental composition of ZnONP's. The performance of the L. sajor-caju-capped ZnONP conjugated with a drug was studied in terms of inhibition of microbial growth against gram-negative and gram-positive bacteria through the disc diffusion method. The results demonstrated a considerable inhibition of both bacteria, demonstrating ZnONP's potential for use in biomedicine.
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PublicationEffect of bolt configurations on stiffness for steel-wood-steel connection loaded parallel to grain for softwoods in Malaysia( 2022)Steel-wood-steel connection is widely seen in many applications, such as timber structures. The stiffness of steel-wood-steel connection loaded parallel to grain for softwoods originated from Malaysia was investigated in this study. Numerical models have been developed in ABAQUS to study the stiffness connection. Softwoods of Damar Minyak and Podo have been selected in this analysis. The comprehensive study focused on the effect of bolt configurations on stiffness. Numerical analysis is carried out and the developed model has been validated with the previous study. Further investigations have been made by using the validated model. From this model, numerical analysis of the stiffness values have been made for various bolt configurations, including bolt diameter, end distance, bolt spacing, number of rows and bolts and edge distance. The result shows that the stiffness of bolted timber connections for softwood depends on the bolt diameter, number of rows and bolts, end distance and edge distance. Based on the result, stiffness increased as the diameter of the bolt, end distance, number of rows and bolts and edge distance increased. It is also discovered that the stiffness equation in Eurocode 5 (EC5) is inadequate as the equation only considered parameters which are wood density and bolt diameter. Other connection parameters such as geometry are not considered in the EC5 equation.
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PublicationScreening biosurfactant‐producing actinomycetes: Identification of Streptomyces sp. RP1 as a potent species for bioremediation( 2024)AbstractThis study aimed to isolate biosurfactant‐producing and hydrocarbon‐degrading actinomycetes from different soils using glycerol–asparagine and starch–casein media with an antifungal agent. The glycerol–asparagine agar exhibited the highest number of actinomycetes, with a white, low‐opacity medium supporting pigment production and high growth. Biosurfactant analyses, such as drop collapse, oil displacement, emulsification, tributyrin agar test, and surface tension measurement, were conducted. Out of 25 positive isolates, seven could utilize both olive oil and black oil for biosurfactant production, and only isolate RP1 could produce biosurfactant when grown in constrained conditions with black oil as the sole carbon source and inducer, demonstrating in situ bioremediation potential. Isolate RP1 from oil‐spilled garden soil is Gram‐staining‐positive with a distinct earthy odor, melanin formation, and white filamentous colonies. It has a molecular size of ~621 bp and 100% sequence similarity to many Streptomyces spp. Morphological, biochemical, and 16 S rRNA analysis confirmed it as Streptomyces sp. RP1, showing positive results in all screenings, including high emulsification activity against kerosene (27.2%) and engine oil (95.8%), oil displacement efficiency against crude oil (7.45 cm), and a significant reduction in surface tension (56.7 dynes/cm). Streptomyces sp. RP1 can utilize citrate as a carbon source, tolerate sodium chloride, resist lysozyme, degrade petroleum hydrocarbons, and produce biosurfactant at 37°C in a 15 mL medium culture, indicating great potential for bioremediation and various downstream industrial applications with optimization.