Irman Abdul Rahman

Ternary phase behaviour and vesicle formation of a sodium N-lauroylsarcosinate hydrate/1-decanol/water system

The phase behaviour of a system composed of amino acid-based surfactant (sodium N-lauroylsarcosinate hydrate), 1-decanol and deionised water was investigated for vesicle formation. Changing the molar ratio of the amphiphiles, two important aggregate structures were observed in the aqueous corner of the phase diagram. Two different sizes of microemulsions were found at two amphiphile-water boundaries. A stable single vesicle lobe was found for 1∶2 molar ratios in 92 wt% water with vesicles approximately 100 nm in size and with high zeta potential value. Structural variation arises due to the reduction of electrostatic repulsions among the ionic headgroups of the surfactants and the hydration forces due to adsorbed water onto monolayers. The balance of these two forces determines the aggregate structures. Analysis was followed by the molecular geometrical structure. These findings may have implications for the development of drug delivery systems for cancer treatments, as well as cosmetic and food formulations.

Effect of Gamma-Irradiation towards Stress-Strain Curve of Single Die QFN Package

The aim of the research was to establish the relationship between stress-strain behaviour of single die Quad Flat No lead (SDQFN) and degradation by gamma irradiation. The SDQFN was exposed to Cobalt-60 with different doses from 0.5 Gy, 1.5 Gy, 5.0 Gy, 10.0 Gy and 50.0 kGy. The three-point bending technique was used to measure the flexural stress and strain of the package behaviour relations. After exposing with gamma radiation, the result showed the decreasing in the strength of the package behaviour of irradiated SDQFN when increasing the dose of gamma irradiation. The highest gamma irradiation dose used in this work produced the highest change in stress-strain behaviour of irradiated SDQFN.

Synthesis and characterization of exfoliated graphene oxide

Graphene oxide has many applications such as in electronic devices, as storage energy device, biosensor, biomedical application, water purification, coating technology, as a composite and paper like materials. Hummer’s method is one of the most common methods used in synthesizing graphene oxide. Graphene is different in size and structure because of oxidized layered of graphene oxide hence, the expanded interlayer structure of graphene oxide can be easily exfoliated by ultrasonication. We report on the preparation of exfoliated graphene oxide by using sonication method. Ultraviolet-visible spectrometer (UV-Vis) and Fourier-Transform Infrared Spectra Analyzer (FTIR) were used to characterize the exfoliated graphite oxide. Exfoliation of graphite oxide is conducted using water bath sonication. In order to confirm the chemical conformation and structure of the produced graphene oxide, FTIR and UV-Vis spectroscopy were utilized. Both peak of C=O and C-C bond are detected using UV-Vis and the results were conf...

Effect of gamma radiation on micromechanical hardness of lead-free solder joint

Lead-free solders are important material in nano and microelectronic surface mounting technology for various applications in bio medicine, environmental monitoring, spacecraft and satellite instrumentation. Nevertheless solder joint in radiation environment needs higher reliability and resistance to any damage caused by ionizing radiations. In this study a lead-free 99.0Sn0.3Ag0.7Cu wt.% (SAC) solder joint was developed and subjected to various doses of gamma radiation to investigate the effects of the ionizing radiation to micromechanical hardness of the solder. Averaged hardness of the SAC joint was obtained from nanoindentation test. The results show a relationship between hardness values of indentations and the increment of radiation dose. Highest mean hardness, 0.2290 ± 0.0270 GPa was calculated on solder joint which was exposed to 5 Gray dose of gamma radiation. This value indicates possible radiation hardening effect on irradiated solder. The hardness gradually decreased to 0.1933 ± 0.0210 GPa and 0.1631 ± 0.0173 GPa when exposed to doses 50 and 500 gray respectively. These values are also lower than the hardness of non irradiated sample which was calculated as 0.2084 ± 0.0.3633 GPa indicating possible radiation damage and needs further related atomic dislocation study.

Gamma Irradiation Effect on Load-Deflection Curve of Semiconductor Package

The effect of different doses of gamma radiation (0.5 Gy, 1.5 Gy, 5.0 Gy, 10.0 Gy and 50 kGy) on the maximum load and deflection of the Single Die Quad Flat No Lead (SDQFN) semiconductor package has been investigated. The three-point technique was carried out to obtain the maximum load and deflection of the package. The results of irradiated SDQFN show the decreasing in their maximum load and deflection with the increasing of gamma irradiation dose. The higher gamma irradiation dose produced the more significant change in the load-deflection behaviour of the irradiated SDQFN. The package becomes prone to failure when exposed to the radiation environment.

Isolation and identification of local bacteria endophyte and screening of its antimicrobial property against pathogenic bacteria and fungi

Endophytes are organisms, often fungi and bacteria that live in living plant cells. These organisms reside in the living tissues of the host plant in a variety of relationships, ranging from symbiotic to slightly pathogenic. The endophytes may produce a plethora of substances that have potential to be used in modern medicine, agriculture and industry. The aims of this study are to isolate, identify and screening antimicrobial activity of bacterial endophytes. The endophytes were isolated using nutrient agar, incubated at 37°C for 48 hours. Identification of the isolates were done based on morphological characteristics, biochemical tests and 16S rDNA molecular analysis. Disk diffusion method was used to screen for antimicrobial activity of metabolites from endophytes against pathogenic bacteria. Screening for antifungal activity of selected endophytes was done using dual culture method againts pathogenic fungi followed by Kirby-Bauer method. Results showed endophytes designated as B2c and B7b have positive antimicrobial activity. The metabolites from isolate B2c showed antimicrobial activity against pathogenic bacteria methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus and Staphylococcus epidermis, while isolate B7b have positive activities againts MRSA, S. aureus and Pseudomonas aeruginosa. Isolates B2c displayed antifungal activity against Fusarium oxysporum, Fusarium solani, Phytophthora palmivora and Colletotrichum gloeosporioides. Identification using biochemical tests and 16S rDNA sequences identified isolate B2c as Pseudomonas resinovorans with 97% homology and isolate B7b as Bacillus subtilis with 98% homology.Endophytes are organisms, often fungi and bacteria that live in living plant cells. These organisms reside in the living tissues of the host plant in a variety of relationships, ranging from symbiotic to slightly pathogenic. The endophytes may produce a plethora of substances that have potential to be used in modern medicine, agriculture and industry. The aims of this study are to isolate, identify and screening antimicrobial activity of bacterial endophytes. The endophytes were isolated using nutrient agar, incubated at 37°C for 48 hours. Identification of the isolates were done based on morphological characteristics, biochemical tests and 16S rDNA molecular analysis. Disk diffusion method was used to screen for antimicrobial activity of metabolites from endophytes against pathogenic bacteria. Screening for antifungal activity of selected endophytes was done using dual culture method againts pathogenic fungi followed by Kirby-Bauer method. Results showed endophytes designated as B2c and B7b have positive...

Pengkapsulan nanozarah gadolinium ke dalam vesikel berasaskan asid amino

Production of amino acid based vesicles using sonication method was employed to determine its encapsulation efficacy towards gadolinium(III) nanoparticles as potential drug carrier. The sonication process involved precursor namely sodium Nlauroylsarcosinate hydrate with 1-decanol to produce vesicle in 92 wt.% of water. Gadolinium(III) nanoparticle was then encapsulated into the vesicle system. The structure of Gd2O2CO3 nanoparticles was confirmed by X-ray Diffraction technique (XRD). Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy indicates the presence of bonding that formed the vesicles. The size distribution of the obtained gadolinium encapsulated vesicle was examined using Transmission Electron Microscopy (TEM). It has been proven to be a potential nano-sized drug carrier.

Effect of Boron Carbide Content on Properties of Thermoplastic Natural Rubber Composite as Thermal Neutron Shielding

In this work, thermoplastic natural rubber (TPNR) composites were produced through melt blending method. Boron carbide (B4C) as filler was added into the polymer blend (TPNR) with different weight percent from 0% to 30% and the effect of different B4C contents on mechanical and thermal neutron attenuation properties of TPNR composites has been studied. The phase formation in composites was analyzed using XRD technique. From the results, it showed that the incorporation of B4C fillers into TPNR matrix has enhanced the macroscopic cross section of the composites, however it lessens the tensile strength. Macroscopic cross section of the composites were increased from 3.34 cm-1 to 14.8 cm-1, while the tensile strength of the composites decreased from 3.79 MPa to 1.06 MPa with increasing B4C from 0 wt% to 30 wt%. B4C diffraction peaks were also increased in intensity with increasing B4C content.

Study on the Effect of γ-Irradiation on Gadolinium Oxysulfide Nanophosphors (Gd2O2S-NPs)

Gadolinium oxysulfide nanophosphors (Gd2O2S-NPs) have been successfully synthesized using γ-irradiation and hydrogenation treatment. The primary stage of Gd2O2S-NPs synthesis was carried out using various doses of γ-irradiation to form diverse sizes of Gd2(SO4)3 precursor, followed by hydrogenation treatment at 900°C for 2 hours to form Gd2O2S-NPs. Then, the nanophosphors were characterized for the structure, morphology, and luminescence properties through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and photoluminescence spectrometer (PL). Pure hexagonal phase of Gd2O2S-NPs was obtained with high crystallinity and without any impurities. The morphologies were observed from grain-like nanostructures transformed to spherical shape as the irradiation dose reached 40 kGy. Besides, Gd2O2S-NPs which were prepared at highest irradiation dose of 40 kGy show highest intensity of emission peak at 548 nm and corresponded to Stark level transition from the state of Gd3+ ion. It can be emphasized that the different doses of γ-irradiation influenced the nucleation event of Gd2(SO4)3 precursor thus affecting the morphology and size particles of Gd2O2S-NPs. Hence, from the results, it can be suggested that Gd2O2S-NPs can be a promising host for optical applications.

Nanoindentation Study on Heat Treated Gold Wire Bonding

The effect of high temperature storage of gold ball bonds towards micromechanical properties has been investigated. Gold wire from thermosonic wire bonding exposed to high temperature storage at 150 °C for 10, 100 and 1000 hours. The nanoindentation test was used in order to evaluate the high temperature storage effect on wire bonding in more details and localized. Prior to nanoindentation test, the specimens were cross-sectioned diagonally. The constant load nanoindentation was performed at the center of gold ball bond to investigate the hardness and reduced modulus. The load-depth curve of nanoindentation for the high temperature storage gold wire has apparent the discontinuity during loading compared to as-received gold wire. The hardness value increased after subjected to high temperature storage. However, the hardness decreased when the storage period is extended. The decreasing in the hardness value may due to the grain size of Au metal which recrystallized after subjected to high temperature storage. The results obtained from nanoindentation is important in assessing the high temperature storage of wire bonding.