The evolution of microemulsion microstructure formed from didodecyl dimethyl ammonium bromide, water and cyclohexane which started from being structureless (fiat scattering profile) to a mean-field Ginsburg-Landau behaviour is shown. The evolution gave the characteristic Lorentzian scattering profile as the system approaches phase separation.
Evolusi mikrostruktur mikroemulsi yang terbentuk daripada didodesil dimetil ammonium bromida, air dan sildoheksana tiada berstruktur (profil serakan yang malar) kepada medan-min Ginsburg-Landau. Evolusi tersebut memberikan serakan Lorentz apabila komposisinya menghampiri sempadan pemisahan fasa.
Nanozarah zink oksida telah disintesis menggunakan afrons gas koloid sebagai acuan. Zink sulfat (ZnSO4.7H2O) dan gas ammonia digunakan sebagi bahan tindak balas. Masa pengeraman yang dikaji adalah 2 jam dan 18 jam. Daripada analisis mikroskop elektron imbasan, morfologi nanohelaian dapat diperhatikan dengan ketebalan helaian 125 nm hingga 200 nm. Daripada analisis spektroskopi ultra lembayung-boleh nampak, saiz purata yang dianggarkan bagi sampel nanozarah zink oksida yang disintesis dengan masa pengeraman 2 jam adalah 2.03 nm dan 2.1 nm untuk sampel yang dieramkan selama 18 jam.
The preformation factor of alpha-decay process in compound nuclei is microscopically proposed with a new perspective. The formation of alpha particle inside the parent nuclei is considered as a quantum-mechanical state which is yielded from a certain interaction among the valance nucleons. This interaction is very similar to that one responsible for the formation of the quasi-bound states in many-body system. This introduced microscopic perspective might give more insight to the understanding of the nuclear structure in the compound nuclei.
Nanozarah Co-Ni-Cu telah disediakan dengan kaedah elektropengendapan pada keupayaan pengendapan -925 mV (SCE) menggunakan larutan sulfat (0.018M Co2++ 0.180M Ni2+ + 0.002M Cu2+) yang mengandungi surfaktan Glukopon 215 CSUP dan juga tanpa surfaktan. Kesan kepekatan surfaktan terhadap saiz dan sifat magnet nanozarah Co-Ni-Cu yang terhasil telah dikaji. Analisis morfologi permukaan endapan yang diperoleh dilakukan dengan menggunakan mikroskop elektron imbasan pancaran medan (FESEM) manakala sifat magnetnya diselidiki dengan menggunakan magnetometer getaran sampel (VSM). Nanozarah Co-Ni-Cu yang disediakan daripada larutan yang mengandungi Glukopon 215 CSUP didapati berbentuk sfera dengan saiz berskala nanometer. Saiz zarah paling kecil ialah lebih kurang 50 nm, diperoleh pada kepekatan surfaktan 5 %v, iaitu kepekatan paling tinggi yang dikaji dalam kajian ini. Kepaksaan (Hc) didapati lebih tinggi pada sampel yang disediakan daripada elektrolit yang mengandungi surfaktan berbanding tanpa surfaktan.
Titanium dioxide nanoparticles were synthesized by using sol gel method and their physico-chemical properties were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectrophotometer. The photocatalytic property of TiO2 nanoparticles was investigated by inactivation of Escherichia coli under irradiation of fluorescent lamp. The results showed that the size of TiO2 was in the range of 3 to 7 nm with high crystallinity of anatase phase. The sharp peaks in FTIR spectrum determined the purity of TiO2 nanoparticles and absorbance peak of UV-Vis spectrum showed the energy band gap of 3.2 eV. Optimum inactivation of E. coli was obtained at 1.0 g/L TiO2 nanoparticles, with 80% of E. coli population was inactivated. The light scattering effect and insufficient concentration are the factors that cause the less effective inactivation reaction for 2.5 g/L and 0.1 g/L TiO2 concentration.
Biosurfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. The unique properties of biosurfactants make them possible to replace or to be added to synthetic surfactants which are mainly used in food, cosmetics and pharmaceutical industries and in environmental applications. In this study twenty hydrocarbon-degrading bacteria were screened for biosurfactant production. All of the bacterial isolates were grown in mineral salt medium (MSM) with addition of 1% (v/v) Tapis crude oil as carbon source. The presence of biosurfactant was determined by the drop-collapse test, microplate analysis, oil spreading technique, emulsification index (%Ei24) and surface tension measurement. Only one isolate, Pseudomonas aeruginosa UKMP14T, was found to be positive for all the qualitative tests and reducing the surface tension of the medium to 49.5 dynes/cm with emulsification index of 25.29%. This isolate produced biosurfactant optimally at pH9.0 and incubation temperature of 37°C. Furthermore, P. aeruginosa UKMP14T when grown in MSM with addition of 1% (v/v) glycerol and 1.3 g/L ammonium sulphate with C/N ratio 14:1 produced biosurfactant with percentage of surface tension reduction at 55% or 30.6 dynes/cm with %Ei 24 of 43%. This percentage of surface tension reduction represents an increasing reduction in surface tension of medium by 39% over the value before optimization. This study showed that P. aeruginosa UKMP14T has the ability to biodegrade hydrocarbon and
concurrently produce biosurfactant.
The purpose of this study was to investigate the effect of annealing to the hardness of high Y2O3-oxide dispersion strengthened (ODS) ferritic steels. The samples were prepared by mechanical alloying method followed by Cold Isostatic Pressing (CIP). After compaction process, the samples were sintered at 1100°C for 1 h in a tube furnace. The crystal structure and morphology of samples were analyzed by X-ray Diffraction (XRD) measurement and characterized by using field emission scanning electron microscope (FESEM), respectively. The hardness of samples was measured by using a micro-Vickers hardness tester with a load of 200 gf at annealing temperature of 600°C, 800°C and 1000°C, respectively. The Vickers hardness value (HV0,2) versus annealing temperature graph showed that the hardness of all samples started to decrease at temperature of 600°C due to grain growth. The hardness value of all samples (1Y and 5Y) identified at this annealing temperature is 855 HV0,2 and 808 HV0, 2, respectively.
Small-angle X-ray scattering (SAXS) was used to investigate the nanostructure of the microfibrils of cell wall in Acacia Mangium wood. Parameters, such as the fibre length (L), surface area of the single fibre (S), the correspondence distance from the center of the fibre to the center of its neighbor and the shape of the fibre were determined as a function to the distance from pith towards the bark. The results indicate that the fibre length ranged from 53.44 nm to 13.72 nm from pith to bark. Surface area of the single fibre varied from 0.65 nm 2 to 4.36 nm 2 , the highest being found at the end of bark region. The mean value of the correspondence distance is 13.95 nm. Surface structure analysis from scattering graph showed a rod shape of fibre in the pith region of Acacia Mangium wood. The use of SAXS technique and scanning electron microscope (SEM) micrographs gives the most reliable dimensions values.
This study attempted to estimate the lifelong magnetic field (MF) exposures of a particular group of welders. Exposure was quantified via measurements, observations and interviews. It was found that these welders face a vast range of lifelong MF exposures depending on the welding processes and duration of the welding tasks performed. This may explain the inconsistency in the results of studies of MF exposures on human health. The mere assessing of the MF exposure levels through spot measurements does not give an overall picture of the total amount of exposure received by the welders as some of these workers performed the welding task throughout the day, whereas others performed this as a part of their job. The exposure to various chemicals in the fume may complicate the interpretation of the elevated health risk among the welders.
Magnetic paper were prepared via the in situ synthesis method with ferrites in the presence of polyethylenimine (PEI). In this work, the thermomechanical pulp (TMP) fibers were used due to low percentage of collapse lumen and the large lumen size for optimum loading degree. Four cycles of the reaction were performed on the TMP fibers with pH values of 4-10. It was found that variation of pH value played an important role in the loading degree of pulp during synthesis process. The magnetic, morphological and structural properties of the magnetic paper obtained were reported. At the
optimum pH of 6.0, saturation magnetization was found to be 3.08 emu/g, remainance magnetization was 0.11 emu/g and coercive force was 12.64 Oe. The optimum loading degree was found to be 23.25%.
Kappa-carrageenan is one form of necessary hydrocolloid. Hydrocolloids are macromolecular materials, which swell upon absorption of water; in some cases, forming a stiff gel in the presence of additives. This property is very important to suspend nanocarriers into gel network, which provide them long time stability at a varying temperature range. In this work, we prepared microemulsion and trapped these particles inside the kappa-carrageenan gel network. The microemulsion was composed of sodium N-lauroylsarcosinate hydrate (SNLS), oleic acid and deionized water. The purpose of this study was to immobilize them into the gel network, giving longer shelf life at a range of temperatures for oral drug delivery. Morphological properties were investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and Fourier transform infrared (FTIR) spectra. The TEM results showed that microemulsions are trapped in the gel network, and the diameter of the microemulsions are below 100 nm, which is comparable with the DLS results. The important functional groups of kappa-carrageenan and microemulsion were shown from the FTIR result of the complex microemulsion gel. These results confirmed the interaction between SNLS based microemulsion and kappa- carrageenan gel.
Combination of magnetic and biocompatible materials to form core-shell nanomaterials has been widely used in medical fields. These core-shell magnetic biomaterials have a great potential for magnetic fluid hyperthermia (MFH) treatment to remedy cancer. The aims of this study were to investigate the production of core-shell cobalt ferrite/polycaprolactone (CoFe2O4/PCL) nanomaterials with different ratios of cobalt ferrite to caprolactone, to study the effects of using polymer in reducing the agglomerations between particles and to determine the structure, morphology, thermal and magnetic properties of these core-shell nanomaterials. The core-shell nanomaterials were produced by in situ polymerization method. The formation of the CoFe2O4/PCL was investigated by means of Fourier transform infrared spectroscopy (FTIR), x-ray diffractometer (XRD) and transmission electron microscopy (TEM). Its thermal properties were determined by using thermogravimetric analyzer (TGA). The vibrating sample magnetometer (VSM) was used to reveal the magnetic properties. The results for the XRD and FTIR spectra demonstrated the formation of cobalt ferrite and polycaprolactone in core-shell nanomaterials. From the TEM results, it was seen that the core-shell CoFe2O4/PCL nanomaterials were best formed at a ratio of CoFe2O4 to monomer caprolactone mixtures of 1:4.
Oleic acid (OA) capped wolfram (VI) oxide, WO3 nanoparticles were chemically synthesized and characterized by means of Fourier Transform-Infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The tribological properties of the capped WO3 nanoparticles as an additive in base oils were investigated using a four-ball machine. Results show that OA-capped WO3 nanoparticles are able to prevent water adsorption and capable of being dispersed stable in organic solvents which is base oils. The as-prepared capped WO3 nanoparticles have an average size of 15 nm. In addition, OA-capped WO3 nanoparticles as an additive in base oils perform good anti-wear (AW) and anti-friction (AF) properties owing to the formation of a boundary film.
Catanionic system using anionic sodium bis-(2ethylhexyl)sulfosuccinate (Am) and cationic cetyltrimethylammonium bromide (cTAB) is studied. The system is prepared by addition of CTAB solution to a prepared AOT solution until slight anionic-rich catanionic phase is produced. Catanionic system consists of the mixture of different types of surfactants and counterion due to electrostatic interaction between the oppositely charged surfactant. Both of these products affect the in surface activity of the surfactant. Hydrodynamic diameters decrease and clearer solution were seen with the increase of CTAB concentration in solution mixture. As a result, mixed surfactant with larger hydrophobic region and the presence of counterion will induce smaller vesicle to form in catanionic system.
Praseodymium ion, Pr3+ doped Gd2
O2
S nanophosphors were successfully synthesized via gamma irradiation route
along with the heat treatment. The effect of the gamma irradiation (0-150 kGy) on the structural, morphology and
photoluminescence properties of Gd2
O2
S:Pr3+ were characterized via X-ray diffraction (XRD), field emission scanning
electron microscope (FESEM) and photoluminescence spectroscopy (PL). The thermal properties of precursor sample
were tested by the thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The chemical bonding of
the precursor samples were analyzed by Fourier transform infrared spectroscopy (FT-IR). The XRD result confirmed the
formation of hexagonal phase of Gd2
O2
S:Pr3+ without the presence of any impurities. The FESEM inspection showed the
non-symmetrical shape of particles transformed into grain-like shape. The optimum photoluminescence (PL) emission
intensities of Gd2-xO2
S:xPr3+ occur at 50 kGy dose of gamma irradiation and 2 mol% concentration dopant of Pr3+ ions.
The spectra under 325 nm UV excitation shows a strong green emission at 515 nm, which match the 3
P0 → 3
H4
transition
of Pr3+ ions. The Gd2
O2
S:Pr3+ nanophosphors possessed many useful approaches in various applications mainly as
radiation detection and biomedical diagnostic.
Unilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) were prepared by the reverse-phase
evaporation method and extrusion through a polycarbonate membrane filter. Liposomes at 0.7 mg/mL lipid concentration
in deionized water were exposed to gamma irradiation at a dose in the range 0.5 to 25 kGy. Gamma irradiation of
liposomes resulted in the degradation of DPPC lipids into free fatty acids, lysophosphatidylcholine and 1,2-palmitoylphosphatidic
acid (DPPA). The effect of gamma irradiation towards the physical stability of liposomes was investigated
by means of dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential analysis. From
the DLS analysis, no significant changes were observed in the hydrodynamic size of liposomes. TEM images indicate that
the liposomes surface became smoother and rounder as higher irradiation doses were applied. Zeta potential analysis
showed that gamma irradiation of DPPC liposomes at radiation doses as low as 0.5 kGy resulted in a drastic rise in the
magnitude of the zeta potential. The results also demonstrate that gamma irradiation of liposomes suspension enhanced
the overall stability of liposomes. Hence, it can be concluded that gamma irradiation on DPPC liposomes may potentially
produce liposomes with higher stability.
Electricity has become one of the necessities for human daily activities. The presence of electric
current produces electromagnetic fields (EMF) at extremely low frequency (ELF). The problem arises
when scientists suggests a possible connection between ELF exposure to human health and safety.
Concerned about the safety and health of students and staff, Universiti Kebangsaan Malaysia (UKM)
took the initiative to identify possible ELF sources and measure their exposure in various locations
around the UKM main campus in Bangi. This paper reports the results obtained from the monitoring
of the magnetic flux density at three identified locations in the vicinity of the overhead high-voltage
transmission line which transverses the university compound and compare the maximum value results
with the exposure limit suggested by the International Committee on Non Ionising Radiation
Protection (ICNIRP) for ELF. Measurements were done with an (Extech) Three Axis
Electromagnetic Field (EMF) Meter (Model 430826) to determine the magnetic flux density. The
lateral profile method was applied as the standard measurement methodology. Results showed that the
maximum value of the magnetic flux density was 12.5 mG, which is below the suggested ICNIRP
public exposure limit of 1000 mG, or in percentage ratio, 1.25% of ICNIRP public exposure limit.
Results from the statistical Kruskal-Wallis test showed that there is a significant difference in the
distributions of the magnetic flux densities at the different locations (P < 0.05). In conclusion, the
measured locations are still safe for people in short-term exposure. However, long-term exposure
measurements still need to be done to provide concrete data on the ELF-emission levels in UKM.
Struktur-nano TiO2 dengan pelbagai saiz dan bentuk telah disintesis melalui kaedah hidrotermal menggunakan serbuk nanozarah TiO2 sebagai prekursor. Sistem hidrotermal yang mudah, murah dan bebas templet pada suhu rawatan 180ºC, pengaruh medium alkali dengan penambahan NaOH dan KOH ke atas saiz, morfologi dan sifat fotovoltaik struktur-nano TiO2 telah dikaji. Sampel telah diperincikan oleh mikroskopi elektron transmisi (TEM), analisis penyebaran tenaga sinar-x (EDAX) manakala keupayaan fotovoltaik sel suria sensitif pewarna (DSSC) diukur menggunakan Gamry Potentiostat Series G-300. Hasil kajian dengan menggunakan agen alkali yang berlainan (NaOH dan KOH) jelas mempengaruhi morfologi TiO2 dan sel suria sensitif pewarna yang terdiri daripada struktur nanorod TiO2 menunjukkan keupayaan terbaik dengan voltan litar terbuka (Voc) sebanyak 416.8 mV, ketumpatan arus litar terbuka (Jsc) sebanyak 0.169 mA/cm2 dan kecekapan penukaran (η) sebanyak 0.0232% di bawah iluminasi lampu xenon AM 1.5.