The studies of ¹³⁷Cs content in the seawater surrounding Peninsular Malaysia had been carried out as part of the Malaysia Marine Radioactivity Database Project. The results of the measurement will serve as the baseline data and reference level to Malaysia. A numbers of sampling locations, including coastal and offshore at the East Coast (South China Sea) and West Coast (Straits of Malacca) of Peninsular Malaysia had been selected for the study. From each location at the coastal area, water samples were collected from the surface of the seawater. Meanwhile, for the offshore area, water samples have been collected at three different depths. Due to usual low concentration of ¹³⁷Cs in the marine environment, large volumes of seawater were collected and the co precipitation technique was employed to concentrate the ¹³⁷Cs. The activity of ¹³⁷Cs was determined by measuring the peak area under photo peak of the gamma spectrum at 661 keV, which is equivalent to the gamma intensity corrected to the HpGe detection efficiency and percentage of gamma ray abundance of the ¹³⁴Cs. At each study location, there were no significant differences for ¹³⁷Cs activities at 95% confidence interval. The activities of ¹³⁷Cs found to be quite uniformly distributed in the range of 2.33 to 5.00 Bq/m3and 1.76 to 4.76 Bq/m3for the South China Sea and the Straits of Malacca, respectively.
Neutron aperture is one of the collimator components in a neutron radiography facility. The optimum design of neutron aperture is very importance in order to obtain largest L/D ratio with highest thermal neutron flux and low gamma-rays at the image plane. In this study, the optimization of neutron aperture parameters were done using Monte Carlo N-Particle Transport Code, version five (MCNP5). This code has a capability to simulate the neutron, photon, and electron or coupled of neutron/photon/electron transport, including the capability to calculate eigen values for critical system. The aperture parameters concerned in this study are the selection of best aperture material, aperture thickness, aperture position and aperture center hole diameter. In these simulations, vacuum beam port medium was applied.
Muhammad Akmal Asraf Mohamad Sharom, Zainol Abidin Ibrahim, Wan Ahmad Tajuddin Wan Abdullah, Megat Harun Al Rashid Megat Ahmad, Faridah Mohamad Idris, Abdul Aziz Mohamed
Small angle neutron scattering (SANS) is used for probing the microstructure of materials in the range between 1-100 nm in dimension. The scattered neutrons from the target material were detected by a 128 x 128 array area sensitive, Helium gas-filled proportional counter, which is known as Position Sensitive Detector (PSD). The small angle neutron scattering (SANS) facility in Malaysian Nuclear Agency has been developed since 1995. The data acquisition system of this prototype facility consists of the two-dimensional Position Sensitive Detector (2D-PSD) and neutron monitor as a data grabber, TDC Histogram as a memory processing processor, two units of ORTEC 994 as a counter and timer and a computer as a data acquisition controller via GPIB interfacing protocol. This paper will describe on the development of GPIB interface for data acquisition of the SANS instrument on Windows based platform. The GPIB device interface and graphical user interface (GUI) for this data acquisition is developed using WaveMetrics Igor software.
One of the non-destructive methods used for the identification and verification of metals is by the energy-dispersive X-ray fluorescence (EDXRF) technique. EDXRF analysis provides several important advantages such as simultaneous determination of the elements present, enable to analyse a very wide concentration range, fast analysis with no tedious sample preparation. The paper shows how this technique is developed and applied in the identification and verification of different grades of stainless steels. Comparison of the results obtained from this analysis with certified reference standards show very small differences between them.
For more than two decades, biodosimetry has been used in biomonitoring of occupational and envir onmental exposure to ionising radiation. Chromosome aberration analysis is a method used to dete ct unstable aberrations in the lymphocytes of irradiated personnel. The Malaysian National Biodosi metry Laboratory is a referance centre for activity relating to biodosimetry in the country. This pap er aims at presenting dicentric assay technique for the assessment of whole body dose to low LET ra diation at the Malaysian National Biodosimetry Laboratory.
A month hourly measurement of radon concentration was taken in the bedroom of a two story link house in Kuala Lumpur. The house is a typical urban house in Malaysia, constructed with bricks, concrete and cement plaster. These materials are natural sources of radon in the house. The hourly radon concentration was found to vary from 0 pCiL-1 to 3 pCiL-1. It was found to peak during early morning and to minimize in the evening. The daily average radon concentration varied from 0.2 pCiL-1 to 1.0 pCiL-1.
Effect of AP+, Ca", Cu" and Fe" on the removal of radium-226 from radium-contaminated soil using humic acid extracted from a Malaysian peat soil was investigated using batch washing method. The concentration of Al,+ Ca", Cu" and Fe" ranged from 0 to 100 ppm. The radioactivity concentration of radium-226 was determined by gamma spectrometer. The removal of radium-226 was enhanced in the presence of AP' with concentration between 20 - 60 ppm. Meanwhile, higher concentration of 80 - 100 ppm did not lead to further increase in the removal of radium-226. The removal of radium-226 was decreased in the presence of Ca" and Cu". In the presence of Fe" with concentration between 20 - 60 ppm, decrease in the removal of radium-226 was also observed. Nevertheless, at concentration between 80 - 100 ppm, the presence of Fe" led to increase in the removal of radium-226.
β-tricalcium phosphate (β-TCP) powders were synthesized by using various particles sizes (40 nm – 780 μm) calcium carbonate (CaCO3) and phosphoric acid (H3PO4) at room temperature (25 ˚C). The synthesized powders were characterized by using X-Ray Diffraction (XRD) method. The purity of β-TCP powders were determined from XRD pattern while the crystallite size of β-TCP powders were calculated by using Scherrer equation. Results shows that the purity of β-TCP powders were ranged from 20.33 % to 81.94 % while the crystallite size of β- TCP powders were ranged from 0.04391 μm to 0.06751 μm. From this work, particle size of CaCO3 will influenced the purity but not the mean crystallite size of synthesized β-TCP.
Herein, we report on the optimum condition for TiO2, titania nanotubes formation and the effect of annealing on the formation of anatase and rutile titania. Anodic oxidation was carried out in two electrodes bath consisting of 5wt% NH4F ions. The anode was a 0.1mm thick Ti foil and the cathode was Pt electrode. Anodisation was conducted at 20V. The anodised foils were subjected to morphological and structural characterizations. As-anodised foil was found to be amorphous or weakly crystalline. When the oxide was heat treated, x-ray diffraction analysis revealed the presence of (101) anatase at annealing temperature from 400-500°C. This indicates that the transformation occurs at this range of temperatures. Raman spectroscopy analysis showed the diminishing of anatase peaks for samples annealed at 500°C. At above 600°C, x-ray diffraction pattern shows a peak belonging to the rutile peak. Transformation from anatase to rutile is thought to occur at about 500°C with a more complete transformation at higher temperature. Annealing at higher than 600°C induces thickening of the nanotubes wall and at above 700°C, the nanotubes structure has completely disappeared.
Silicon nanostructures have successfully been synthesized by thermal evaporation technique using nickel catalyst. Silicon powder served as starting source material was evaporated at high temperature (900-1100°C) in inert carrier gas. The grown silicon nanostructures were collected on (111) silicon substrate surface that positioned at varied location from source material. By controlling heating rate, gas flow rate, growth temperature and time, substrate position and location; to the optimum condition produced the best quality at silicon nanostructures. In this work, the best parameter to produce silicon nanostructures is system ramping up 1000°C at 20°C/min heating rate, N2 flow at 100ml/min; silicon needle-like one dimensional silicon nanostructures growth on vertically-positioned substrate located at 12cm from source material for 1 hour growth time. The effects of these parameters on the structures and physical of nanostructures were characterized by field emission scanning electron microscope and x-ray diffraction.
The microstructure, tensile fracture and creep fracture of as-cast beta phase contained γ-TiAl with nominal composition of Ti-48Al-4Cr (at.%) was investigated. The effect of beta phase on tensile and creep strength was determined from fracture analysis. Tensile test were performed at room temperature whereas constant load tensile creep test were performed at temperature 800 0 C and initial stress of 150MPa. Initial as-cast microstructure, microstructure and fracture surface after tensile and creep test were examined using scanning electron microscopy technique. Analysis shows brittle fracture after room temperature tensile test whereas ductile fracture after high temperature creep test. The role of beta phase was discussed. It is concluded that beta phase is sensitive to temperature and detrimental at both room and high temperature.
Currently, research in composite materials is being directed at using natural fibers instead of synthetics fibers. The use of natural fibers, derived from annually renewable resources, as reinforcing fibers in matrix provides positives environmental benefits with respect to ultimate disposability and raw material utilization. Natural fiber offers an alternative to the technical reinforcing fibers because of their low density, good mechanical performance, ultimate availability and disposability. Modifying the fiber surface by using chemical treatment can enhance bond strength between fiber and matrix. Chemical treatment also an effective way to clean the fiber surface, chemically modify the surface and increase the surface roughness. Surface analyses on fiber for before and after treatment were investigated using scanning electron microscopy (SEM).
This paper studies the use of gamma irradiation for textile waste water treatment. Prior to irradiation, the raw wastewa ter was diluted using tap water to targeted concentration of COD 400 mg/l. The sample was irradiated at selected dose between the ranges of 2kGy to 100kGy. The results showed that Irradiation was effective in removing the highly colored refractory organic pollutants. The COD removal at lowest dose, 2kGy is about 310 mg/l. Meanwhile, at highest dose, 1 00kGy the COD reduced to 100mg/l. The degree of removal influenced by the dose introduced during the treatment pro cess. As the dose increased, higher removal of organic pollutant was recorded. On the other hand, other properties of t he wastewater such as pH, turbidity, suspended solid, BOD and color shows tremendous changes as the dose increases. This shows the concentration of pollutants and dose of irradiation applied are directly proportional to each other.
Triyttrium Pentairon (iii) Oxide (Y3Fe501,2) or familiar called as Yttrium Iron Garnet (YIG) is successfully prepared using a conventional mixed-oxide method of 5:3 Fe to Y ratios. YIG prepared from conventional mixed-oxide usually produced some associated phase which surely will affect electrical properties. In this study, various temperature used in the sintering process to induce associated phases (YIP) to be fully reacting to form single phase of YIG and the effect on resonance frequency is studied for resonator applications. The mixtures of oxide powders are calcined at 1100 "C and sintered at various temperatures of (1350, 1380, 1400, 1420 1450 QC, respectively). Cubic phase is detected from the formation of YIG. Some other phases such as YIP and hematite also present as secondary phase. However, it is seen that, based on the Rietvield refinement method, the total amount of secondary phase simulated are inversely proportional with sintering temperature. The powder was pressed into cylindrical pellet and tested as a microwave resonator in antenna application. It was found that, on the actual antenna circuit the operating frequencies measured are in the range of 10-12 GHz for all samples which suitable for X-band. At the end, overall radiation pattern for all samples exhibit an omnidirectional behavior.
Ceramic foams are a class of high porosity materials that are used or being considered for a wide range of technological applications. Ceramic foam was produce by polymer replication method. In this process, commercial polymeric sponge was use as template, dipping with ceramic particles slurry, drying and then sintered to yield a replica of the original foams. The study was focus on the fabrication of different density of ceramic foams by varying the density of ceramic slurries (1.1876, 1.2687, 1.3653 and 1.5295 g/cm3). Properties of ceramic foam produced such as density was characterized accordingly to ASTM C 271-94 and porosity were characterized using Archimedes methods. Compressive and bending strength was performed accordingly to ASTM C1161-94 and C773-88 (1999), respectively. The morphological study was performed using Scanning Electron Microscopy (SEM) and EDX. Density of ceramic foams produced was about 0.5588 and 1.1852 g/cm3, where as porosity was around 26.28 and 70.59 %. Compressive and bending strength was increase from strength also increases from 2.60 to 23.07 MPa and 1.20 to 11.10 MPa, respectively, with increasing of slurries density from 1.1876 to 1.3653 g/cm3. The SEM micrographs show that the cells structure become denser as the slurries density increased. EDX proved that the ceramic used is porcelain. As a conclusion, increasing in slurries density produced ceramic foams with good mechanical properties such as compressive and bending strength and denser body.
Various palm oil (RBD Palm Olein) based urethane acrylate prepolymers (UPs) having different structures and molecular weights were synthesised from palm oil based polyols, diisocyanate compounds and hydroxyl terminated acrylate monomers by following established synthesis procedures described elsewhere. The products (UPs) were compared with each other in terms of their molecular weights (MW), viscosities and UV curing performances of pressure sensitive adhesives (PSA) UP based formulations. The molecular structure of diisocyanate compounds and hydroxyl acrylate monomers tend to determine the molecular weights and hence viscosities of the final products of urethane acrylate prepolymers (UP), whereas, the MW of the UP has no direct effects on the coatings and adhesive properties of UV curable UP based PSA.
The extracellular matrix (ECM) is a complex structural entity surrounding and supporting cells that
are found within mammalian tissue. This study presents the effect of ionizing radiation on the physical
properties of elastin which is usually found within arteries, lung, skin, ligantum nuchae, vocal chords
and elastic cartilage as a function of their composition and organization or architecture. X-ray from
an electron linac were used to give doses of 10-50Gy to cover the range of irradiation exposure during
radiotherapy. A uniaxial mechanical testing protocol was used to characterize the fibrous protein. For
pericardial the major change was an increase in the elastic modulus in the toe region of the curve (≤
20% strain), from 23±18 kPa for controls to 57±22 kPa at a dose of 10 Gy (p=0.01, α=0.05). At a
larger strain (≤ 20%), the elastic modulus in the region decreased from 1.92±0.70 MPa for control
pericardium tissue to 1.31±0.56 MPa (p=0.01, α=0.05) for 10 Gy X-irradiated sample. For elastin,
the stress-strain relationship was linear up to 30% strain, but the elastic modulus decreased
significantly with irradiation (controls 626±65 kPa, irradiated 474±121 kPa (p=0.02, α=0.05). The
results suggest that for elastin chain scissions are the primary effect of irradiation. The Raman
microspectrometry was employed to characterize these changes on ECM conformation.
The effects of radiation on tissue have generally been investigated in the context of therapeutic
irradiations, radiation protection and exposure to solar radiation. Typically attention has
concentrated primarily on cells, less consideration being given to the extracellular matrix (ECM).
ECM consists of collagen and elastin fibers immersed in a viscoelastic gel composed principally of
hyaluronan (HA) and proteoglycans. The present study examines changes in the physical properties of
the principle matrix micromolecules due to exposure to ionizing radiation. Freeze-dried rooster-comb
HA (Sigma) were used to give doses of 10-100 Gy for HA, to cover the range of irradiation exposure
during radiotherapy. The viscosity of HA (at 1.25% and 0.125% w/v) was measured by both cone and
plate and capillary viscometry, the former providing measurement at uniform shear rate and the latter
providing a more sensitive indication of changes. The Raman microspectrometry was employed to
characterize these changes on ECM molecular conformation. In regard to the viscometry, both
techniques (cone and plate and capillary viscometry) reveal a dose-dependent reduction in viscosity
(from 340 ± 194 cP for controls to 1500 ± 88 cP at a shear rate of 2 s-1 and dose of 75 Gy), again
suggesting depolymerisation.
Among the challenges for superconducting devices to be applied in industry are the need for high transport critical current density (Jr) and sustainability of the device in different environment. For superconducting material to maintain high 4, effective flux pinning centers are needed. The addition of small size MgO particles in bulk Bi2Sr2CaCu2O8 (Bi-2212) superconductor has been proven to enhance the effective flux pinning centers in the superconducting material. Nevertheless, the flux pinning properties of the superconducting materials may change if they are exposed to radioactive environment. Electron irradiation is one of the common techniques that can be used to study the impact of irradiation on superconducting materials. In this work, a small amount of nanosize MgO particles were used as the flux pinning centers for Bi-2212 superconducting material. The Bi-2212/MgO composite was heat treated and followed by partial melting and slow cooling. Some of the samples were subjected to electron irradiation using the facility at the Malaysian Nuclear Agency. Characterizations of non-irradiated and irradiated samples were performed via X-ray Diffraction Patterns (XRD), Scanning Electron Microscopy (SEM) and measurements of J, dependence on temperature in self-field. Higher J, indicates better flux pinning properties in irradiated superconductor composite. This is achieved if defects with larger radius with dimension comparable to the coherence length of the superconducting material were created. On the other hand, decreased in Je indicates ineffective flux pinning and this is attributed to the overlapping of defects that break the superconducting region. Our study showed that electron irradiation deteriorated the flux pinning properties of the Bi-2212/MgO superconductor composite.
Protocorm-like bodies (PLBs) of an orchid (Oncidium lanceanum) were irradiated using 220 MeV 12 C 5+ ions, accelerated by AVF cyclotron at JAEA, Japan in 2005. Five different doses were applied to the PLBs; 0, 1.0, 2.0, 6.0 and 12.0 Gy. Following irradiation, these PLBs were maintained in cultures for germination and multiplication. Irradiation effects on growth and seedling regeneration patterns as well as molecular characteristics of the in vitro cultures were monitored and recorded. In general, average fresh weights of the irradiated PLBs increased progressively by irradiating the explants at 1.0, 2.0 and reached the maximum at 6.0 Gy. The figure however dropped when the explants were irradiated at 12 Gy. Surprisingly, although the highest average fresh weight was recorded on PLBs irradiated at 6.0 Gy, most of these PLBs were not able to regenerate into complete shoots. On average, after 4 months of irradiation, only 21 seedlings were successfully regenerated from each gram of these PLBs. The highest shoot regeneration was recorded on cultures irradiated at 2.0 Gy in which 102 seedlings were obtained from one gram of the PLBs. Some morphological changes were seen on in vitro plantlets derived from PLBs irradiated at doses of 1.0 and 2.0 Gy. Most of the regenerated seedlings have been transferred to glasshouse for further morphological selection. Molecular analysis showed the presence of DNA polymorphisms among the seedlings from different doses of irradiation.