Advanced Materials Research Vol. 620

Abstract: This study covers the effect of ferrous chloride (FeCl₂) concentration on the formation of iron oxide nanoparticles (IONPs) via the precipitation method. IONPs with appropriate surface functionalization were synthesized in order to obtain a stable colloidal IONPs (ferrofluid) for the conjugation process. The electrostatic repulsion using percloric acid (HClO₄) and steric stabilization using silane polyethelene glycol (SiPEG) were generated. The optimum concentration of FeCl₂ was at 0.3 M. From the transmission electron microscopy (TEM) image, the size of IONPs obtained was ~13 nm. The stable IONPs were then conjugated to the antibody and tested in the lateral flow immunoassay as the labelling agent. The conjugated IONPS with the antibody was proven sensitive to the Brugian Filiarisis disease.

Abstract: This study investigated the effect of Ag addition on the morphology and growth rate of Cu₅Zn₈, Cu₆Sn₅ and Cu₃Sn intermetallics in the Sn-8Zn-3Bi solder. The solder was prepared by mixing 1wt% of Ag into 99wt% of Sn-8Zn-3Bi solder. The intermetallics were formed by liquid-state aging, whereby the solders were reacted on Cu substrate above the melting temperature of the solder. The reflow was done at 250°C and 270°C at various soldering times. A scanning electron microscope (SEM) was used to observe the morphology of the intermetallic phase and energy dispersive X-ray (EDX) was used to identify the elemental composition. The Sn-8Zn-3Bi solder reacting with Cu substrate formed a single Cu₅Zn₈ intermetallic layer with a flat structure. On the other hand, the reaction between (Sn-8Zn-3Bi)-1Ag solder and Cu substrate produces Cu₆Sn₅ intermetallic. This Cu₆Sn₅ intermetallic has a scallop structure. As the soldering time increases, a second layer, identified as Cu₃Sn starts to grow. The thickness of the intermetallics increases with aging temperatures and time. The addition of Ag into the Sn-8Zn-3Bi solder has significantly suppressed the formation of Cu₅Zn₈ intermetallic and promoted the growth of Cu₆Sn₅ intermetallic.

Abstract: Sol-gel silica-supported mineral acids (namely sol-gel perchloric acid (slg HClO₄), sulfuric acid (slg H₂SO₄) and phosphoric acid (slg H₃PO₄), prepared by incorporating mineral acids molecules into silica via sol-gel technique, were used as an efficient heterogeneous catalyst for the direct addition reaction of oleic acid (OA) to form estolides compound. The reactions were carried out under vacuum (2 mBar) for 10 hours at 70°C under solvent-less conditions. Liquid chromatography-mass spectrometry time of flight (LC-MS ToF) of reaction products results showed chromatographic peaks for the presence of two new estolide compounds, oleic-oleic monoestolide acid (m/z 563.51, as [M-^-), and oleic-oleic diestolide acid (m/z 845.77 [M-^-). The HClO sol-gel catalyst turned out to be the best catalyst, achieving a final conversion of 76.4% with 83.4% selectivity to oleic-oleic monoestolide acid (OOM) and 16.6% selectivity to oleic-oleic diestolide acid (OOD). The activity and selectivity of the mineral acid sol-gel catalysts have been investigated and compared with homogeneous HClO₄. The samples were characterised by XRD, TPD-NH₃ and XPS.

Abstract: The green SrAl₂O₄:Eu²⁺, Dy³⁺ phosphor is a well-known persistent material for a wide region of applications such as lighting, traffic signs, interior decoration and medical application. Double activated SrAl₂O₄:Eu²⁺, Dy³⁺ with improved properties has been synthesized through solid state route at different firing atmospheres (reduction, vacuum, oxygen and CO₂ wet gas) and heating times (1 h to 8 h). At the beginning the powders were heat treated for 2 h with a heating rate of 10°C/min. The phosphor prepared at different firing atmospheres and heating times exhibited a different wavelength and intensity of PL spectra. The emission intensity becomes stronger as the heating times increases from 1 h to 4 h. The difference found from these spectra maxima is rationalized based on the presence of intermediate phases and also on the diffusion activities of activator and co-activator in the host matrices.

Abstract: Recyclability effect on catalytic performance of Ru supported on the mixture of bentonite-TiO₂ for the hydrogenolysis of glycerol was investigated under reaction condition of 150°C, 2.0 MPa hydrogen pressure and 7 h reaction time. Interestingly, the recovered Ru/bentonite-TiO₂ catalyst was found to be active in the repeated runs. The conversion of glycerol increased in the four successive reactions as follows: 61.3%, 65.6%, 68.1% and 75.3%. This suggested that a sort of metal activation affect such as in situ reduction occurred during the repeated reaction. In order to confirm in situ reduction had occurred during the repeated reaction, XPS analysis of used catalyst after each reaction were carried out to study the chemical state of Ru 3d species. Narrow scan of peak Ru 3d revealed that intensity of Ru 3d_5/2 peak at BE 280.0 eV which is corresponding to Ru⁰ species increased until three cycle reaction. This result confirmed that in situ reduction had occurred during the repeated reaction and this made the activities of the catalyst increased upon recycling due to the availability of more metallic Ru on the surface of the catalyst. This study also shows that conversion of glycerol increased linearly with the percentage atomic ratio of Ru metal active site available on the surface of catalyst.

Abstract: ndialite or α-cordierite was synthesized by glass crystallization method. Effect of different sintering profile; single stage sintering (1s) and two stages sintering (2s) on phase formation was determined via x-ray diffraction (XRD) analysis using rietvield method of HighScore Plus software. It has been found that 1s produce 85 % of α-cordierite with 15 % anorthite as secondary phase while, α-cordierite appeared about 68.6 % with 24.3 % anorthite and 7.1 % forsterite as secondary phase using 2s sintering profile.

Abstract: Cellulose microfibril from banana pseudo-stem fiber waste has been isolated and characterised. Isolation of microfibril cellulose from raw fibers was achieved using alkaline treatment and bleaching. The treated and untreated samples were characterized using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Characterizations of treated and untreated samples were compared. XRD studies shows that the treated cellulose prepared by alkaline and bleaching treatment was more crystalline than the untreated banana fiber. Surface morphological studies using FESEM shows there was a reduction in fiber diameter during the chemical treatment.

Abstract: Ti₃SiC₂ compound was synthesized from the starting powder mixtures of 3Ti/1.2Si/2C/xAl (x=0, 0.1, 0.2, 0.3) by using arc melting method. The effect of Al on the Ti₃SiC₂ formation was studied. X-ray diffraction and scanning electron microscopy were used to characterize the synthesized materials. It was found that the addition of Al increased the purity of Ti₃SiC₂. When x=0.2, Ti₃SiC₂ content in the final product reached 67% after being ball milled for 24 hours. However, excessive Al reduced the content of Ti₃SiC₂. In addition, the density of the final product decreased with increasing of Al content. It was revealed that addition of Al in the starting powders can increase the final product purity.

Abstract: The effects of ball-milling parameter on the structures and properties of the synthesis of multi-walled carbon nanotubes (MWCNT)/alumina hybrid compound via methane decomposition process using Ni-Alumina catalyst were researched. The structural evaluation of particles compound was investigated by particle size analysis, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), FTIR spectrometer and scanning electron microscopy (SEM). The results indicated that with 300rpm 15h, the microstructure of the hybrid compound is greatly refined, and methane decomposition process distributed uniformly, thus increasing the efficiency of the carbon nanotubes growth process.

Abstract: Hardwood is wood from angiosperm trees. The characteristic of hardwood include flowers, endosperm within seeds and the production of fruits that contain the seeds. This paper aims to discuss the preparation and characterization of cellulose obtained from hardwood. The hardwood Merbau (Intsia bijuga) was chosen as raw material in this study. Alkaline treatment and delignification methods were used for the preparation of cellulose. Acid hydrolysis was employed to produce cellulose nanocrystal (CNC). The treated and untreated samples were characterized using x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The final product, from both trated and untreated samples were then compared.