Displaying publications 141 - 160 of 170 in total

Abstract:
Sort:
  1. Khan MUA, Haider S, Shah SA, Razak SIA, Hassan SA, Kadir MRA, et al.
    Int J Biol Macromol, 2020 May 15;151:584-594.
    PMID: 32081758 DOI: 10.1016/j.ijbiomac.2020.02.142
    Arabinoxylan (AX) is a natural biological macromolecule with several potential biomedical applications. In this research, AX, nano-hydroxyapatite (n-HAp) and titanium dioxide (TiO2) based polymeric nanocomposite scaffolds were fabricated by the freeze-drying method. The physicochemical characterizations of these polymeric nanocomposite scaffolds were performed for surface morphology, porosity, swelling, biodegradability, mechanical, and biological properties. The scaffolds exhibited good porosity and rough surface morphology, which were efficiently controlled by TiO2 concentrations. MC3T3-E1 cells were employed to conduct the biocompatibility of these scaffolds. Scaffolds showed unique biocompatibility in vitro and was favorable for cell attachment and growth. PNS3 proved more biocompatible, showed interconnected porosity and substantial mechanical strength compared to PNS1, PNS2 and PNS4. Furthermore, it has also showed more affinity to cells and cell growth. The results illustrated that the bioactive nanocomposite scaffold has the potential to find applications in the tissue engineering field.
    Matched MeSH terms: Stress, Mechanical
  2. Shimoda K, Nishimura A, Sunggip C, Ito T, Nishiyama K, Kato Y, et al.
    Sci Rep, 2020 08 18;10(1):13926.
    PMID: 32811872 DOI: 10.1038/s41598-020-70956-5
    Cardiac tissue remodeling caused by hemodynamic overload is a major clinical outcome of heart failure. Uridine-responsive purinergic P2Y6 receptor (P2Y6R) contributes to the progression of cardiovascular remodeling in rodents, but it is not known whether inhibition of P2Y6R prevents or promotes heart failure. We demonstrate that inhibition of P2Y6R promotes pressure overload-induced sudden death and heart failure in mice. In neonatal cardiomyocytes, knockdown of P2Y6R significantly attenuated hypertrophic growth and cell death caused by hypotonic stimulation, indicating the involvement of P2Y6R in mechanical stress-induced myocardial dysfunction. Unexpectedly, compared with wild-type mice, deletion of P2Y6R promoted pressure overload-induced sudden death, as well as cardiac remodeling and dysfunction. Mice with cardiomyocyte-specific overexpression of P2Y6R also exhibited cardiac dysfunction and severe fibrosis. In contrast, P2Y6R deletion had little impact on oxidative stress-mediated cardiac dysfunction induced by doxorubicin treatment. These findings provide overwhelming evidence that systemic inhibition of P2Y6R exacerbates pressure overload-induced heart failure in mice, although P2Y6R in cardiomyocytes contributes to the progression of cardiac fibrosis.
    Matched MeSH terms: Stress, Mechanical
  3. Mehboob H, Tarlochan F, Mehboob A, Chang SH, Ramesh S, Harun WSW, et al.
    J Mater Sci Mater Med, 2020 Aug 20;31(9):78.
    PMID: 32816091 DOI: 10.1007/s10856-020-06420-7
    The current study is proposing a design envelope for porous Ti-6Al-4V alloy femoral stems to survive under fatigue loads. Numerical computational analysis of these stems with a body-centered-cube (BCC) structure is conducted in ABAQUS. Femoral stems without shell and with various outer dense shell thicknesses (0.5, 1.0, 1.5, and 2 mm) and inner cores (porosities of 90, 77, 63, 47, 30, and 18%) are analyzed. A design space (envelope) is derived by using stem stiffnesses close to that of the femur bone, maximum fatigue stresses of 0.3σys in the porous part, and endurance limits of the dense part of the stems. The Soderberg approach is successfully employed to compute the factor of safety Nf > 1.1. Fully porous stems without dense shells are concluded to fail under fatigue load. It is thus safe to use the porous stems with a shell thickness of 1.5 and 2 mm for all porosities (18-90%), 1 mm shell with 18 and 30% porosities, and 0.5 mm shell with 18% porosity. The reduction in stress shielding was achieved by 28%. Porous stems incorporated BCC structures with dense shells and beads were successfully printed.
    Matched MeSH terms: Stress, Mechanical
  4. Tilwani RK, Vessillier S, Pingguan-Murphy B, Lee DA, Bader DL, Chowdhury TT
    Inflamm Res, 2017 Jan;66(1):49-58.
    PMID: 27658702 DOI: 10.1007/s00011-016-0991-5
    OBJECTIVE AND DESIGN: Oxygen tension and biomechanical signals are factors that regulate inflammatory mechanisms in chondrocytes. We examined whether low oxygen tension influenced the cells response to TNFα and dynamic compression.

    MATERIALS AND METHODS: Chondrocyte/agarose constructs were treated with varying concentrations of TNFα (0.1-100 ng/ml) and cultured at 5 and 21 % oxygen tension for 48 h. In separate experiments, constructs were subjected to dynamic compression (15 %) and treated with TNFα (10 ng/ml) and/or L-NIO (1 mM) at 5 and 21 % oxygen tension using an ex vivo bioreactor for 48 h. Markers for catabolic activity (NO, PGE2) and tissue remodelling (GAG, MMPs) were quantified by biochemical assay. ADAMTS-5 and MMP-13 expression were examined by real-time qPCR. 2-way ANOVA and a post hoc Bonferroni-corrected t test were used to analyse data.

    RESULTS: TNFα dose-dependently increased NO, PGE2 and MMP activity (all p 

    Matched MeSH terms: Stress, Mechanical
  5. Elshereksi NW, Ghazali MJ, Muchtar A, Azhari CH
    J Dent, 2017 Jan;56:121-132.
    PMID: 27916635 DOI: 10.1016/j.jdent.2016.11.012
    OBJECTIVES: This study aimed to fabricate and characterise silanated and titanated nanobarium titanate (NBT) filled poly(methyl methacrylate) (PMMA) denture base composites and to evaluate the behaviour of a titanate coupling agent (TCA) as an alternative coupling agent to silane. The effect of filler surface modification on fracture toughness was also studied.

    METHODS: Silanated, titanated and pure NBT at 5% were incorporated in PMMA matrix. Neat PMMA matrix served as a control. NBT was sonicated in MMA prior to mixing with the PMMA. Curing was carried out using a water bath at 75°C for 1.5h and then at 100°C for 30min. NBT was characterised via Fourier transform-infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis before and after surface modification. The porosity and fracture toughness of the PMMA nanocomposites (n=6, for each formulation and test) were also evaluated.

    RESULTS: NBT was successfully functionalised by the coupling agents. The TCA exhibited the lowest percentage of porosity (0.09%), whereas silane revealed 0.53% porosity. Statistically significant differences in fracture toughness were observed among the fracture toughness values of the tested samples (p<0.05). While the fracture toughness of untreated samples was reduced by 8%, an enhancement of 25% was achieved after titanation. In addition, the fracture toughness of the titanated samples was higher than the silanated ones by 10%.

    CONCLUSION: Formation of a monolayer on the surface of TCA enhanced the NBT dispersion, however agglomeration of silanated NBT was observed due to insufficient coverage of NBT surface. Such behaviour led to reducing the porosity level and improving fracture toughness of titanated NBT/PMMA composites. Thus, TCA seemed to be more effective than silane.

    CLINICAL SIGNIFICANCE: Minimising the porosity level could have the potential to reduce fungus growth on denture base resin to be hygienically accepTable Such enhancements obtained with Ti-NBT could lead to promotion of the composites' longevity.

    Matched MeSH terms: Stress, Mechanical
  6. Chasis JA, Mohandas N
    J. Cell Biol., 1986 Aug;103(2):343-50.
    PMID: 3733870
    Skeletal proteins play an important role in determining erythrocyte membrane biophysical properties. To study whether membrane deformability and stability are regulated by the same or different skeletal protein interactions, we measured these two properties, by means of ektacytometry, in biochemically perturbed normal membranes and in membranes from individuals with known erythrocyte abnormalities. Treatment with 2,3-diphosphoglycerate resulted in membranes with decreased deformability and decreased stability, whereas treatment with diamide produced decreased deformability but increased stability. N-ethylmaleimide induced time-dependent changes in membrane stability. Over the first minute, the stability increased; but with continued incubation, the membranes became less stable than control. Meanwhile, the deformability of these membranes decreased with no time dependence. Biophysical measurements were also carried out on pathologic erythrocytes. Membranes from an individual with hereditary spherocytosis and a defined abnormality in spectrin-protein 4.1 association showed decreased stability but normal deformability. In a family with hereditary elliptocytosis and an abnormality in spectrin self-association, the membranes had decreased deformability and stability. Finally, membranes from several individuals with Malaysian ovalocytosis had decreased deformability but increased stability. Our data from both pathologic membranes and biochemically perturbed membranes show that deformability and stability change with no fixed relationship to one another. These findings imply that different skeletal protein interactions regulate membrane deformability and stability. In light of these data, we propose a model of the role of skeletal protein interactions in deformability and stability.
    Matched MeSH terms: Stress, Mechanical
  7. Ooi CH, Ling YP, Abdullah WZ, Mustafa AZ, Pung SY, Yeoh FY
    J Mater Sci Mater Med, 2019 Mar 30;30(4):44.
    PMID: 30929088 DOI: 10.1007/s10856-019-6247-5
    Hydroxyapatite is an ideal biomaterial for bone tissue engineering due to its biocompatibility and hemocompatibility which have been widely studied by many researchers. The incorporation of nanoporosity into hydroxyapatite could transform the biomaterial into an effective adsorbent for uremic toxins removal especially in artificial kidney system. However, the effect of nanoporosity incorporation on the hemocompatibility of hydroxyapatite has yet to be answered. In this study, nanoporous hydroxyapatite was synthesized using hydrothermal technique and its hemocompatibility was determined. Non-ionic surfactants were used as soft templates to create porosity in the hydroxyapatite. The presence of pure hydroxyapatite phase in the synthesized samples is validated by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The TEM images show that the hydroxyapatite formed rod-like particles with the length of 21-90 nm and diameter of 11-70 nm. The hydroxyapatite samples exhibit BET surface area of 33-45 m2 g-1 and pore volume of 0.35-0.44 cm3 g-1. The hemocompatibility of the hydroxyapatite was determined via hemolysis test, platelet adhesion, platelet activation and blood clotting time measurement. The nanoporous hydroxyapatite shows less than 5% hemolysis, suggesting that the sample is highly hemocompatible. There is no activation and morphological change observed on the platelets adhered onto the hydroxyapatite. The blood clotting time demonstrates that the blood incubated with the hydroxyapatite did not coagulate. This study summarizes that the synthesized nanoporous hydroxyapatite is a highly hemocompatible biomaterial and could potentially be utilized in biomedical applications.
    Matched MeSH terms: Stress, Mechanical
  8. Yusoff N, Abu Osman NA, Pingguan-Murphy B
    Med Eng Phys, 2011 Jul;33(6):782-8.
    PMID: 21356602 DOI: 10.1016/j.medengphy.2011.01.013
    A mechanical-conditioning bioreactor has been developed to provide bi-axial loading to three-dimensional (3D) tissue constructs within a highly controlled environment. The computer-controlled bioreactor is capable of applying axial compressive and shear deformations, individually or simultaneously at various regimes of strain and frequency. The reliability and reproducibility of the system were verified through validation of the spatial and temporal accuracy of platen movement, which was maintained over the operating length of the system. In the presence of actual specimens, the system was verified to be able to deliver precise bi-axial load to the specimens, in which the deformation of every specimen was observed to be relatively homogeneous. The primary use of the bioreactor is in the culture of chondrocytes seeded within an agarose hydrogel while subjected to physiological compressive and shear deformation. The system has been designed specifically to permit the repeatable quantification and characterisation of the biosynthetic activity of cells in response to a wide range of short and long term multi-dimensional loading regimes.
    Matched MeSH terms: Stress, Mechanical
  9. Madfa AA, Kadir MR, Kashani J, Saidin S, Sulaiman E, Marhazlinda J, et al.
    Med Eng Phys, 2014 Jul;36(7):962-7.
    PMID: 24834856 DOI: 10.1016/j.medengphy.2014.03.018
    Different dental post designs and materials affect the stability of restoration of a tooth. This study aimed to analyse and compare the stability of two shapes of dental posts (parallel-sided and tapered) made of five different materials (titanium, zirconia, carbon fibre and glass fibre) by investigating their stress transfer through the finite element (FE) method. Ten three-dimensional (3D) FE models of a maxillary central incisor restored with two different designs and five different materials were constructed. An oblique loading of 100 N was applied to each 3D model. Analyses along the centre of the post, the crown-cement/core and the post-cement/dentine interfaces were computed, and the means were calculated. One-way ANOVAs followed by post hoc tests were used to evaluate the effectiveness of the post materials and designs (p=0.05). For post designs, the tapered posts introduced significantly higher stress compared with the parallel-sided post (p<0.05), especially along the centre of the post. Of the materials, the highest level of stress was found for stainless steel, followed by zirconia, titanium, glass fibre and carbon fibre posts (p<0.05). The carbon and glass fibre posts reduced the stress distribution at the middle and apical part of the posts compared with the stainless steel, zirconia and titanium posts. The opposite results were observed at the crown-cement/core interface.
    Matched MeSH terms: Stress, Mechanical
  10. Beh YH, Halim MS, Ariffin Z
    PeerJ, 2023;11:e16469.
    PMID: 38025677 DOI: 10.7717/peerj.16469
    BACKGROUND: This study aimed to evaluate the load capacity of maxillary central incisors with simulated flared root canal restored with different fiber-reinforced composite (FRC) post cemented with either self-adhesive or self-etch resin cement and its mode of fracture.

    METHODS: Sixty-five extracted maxillary incisors were decoronated, its canal was artificially flared and randomly categorized into group tFRC (tapered FRC post) (n = 22), mFRC (multi-FRC post) (n = 21), and DIS-FRC (direct individually shaped-FRC (DIS-FRC) post) (n = 22), which were further subdivided based on cementation resin. The posts were cemented and a standardized resin core was constructed. After thermocycling, the samples were loaded statically and the maximum load was recorded.

    RESULTS: The load capacity of the maxillary central incisor was influenced by the different FRC post system and not the resin cement (p = 0.289), and no significant interaction was found between them. Group mFRC (522.9N) yielded a significantly higher load capacity compared to DIS-FRC (421.1N). Overall, a 55% favorable fracture pattern was observed, and this was not statistically significant.

    CONCLUSION: Within the limitation of the study, it can be concluded that prefabricated FRC posts outperform DIS-FRC posts in terms of the load capacity of a maxillary central incisor with a simulated flared root canal. The cementation methods whether a self-adhesive or self-etch resin cement, was not demonstrated to influence the load capacity of a maxillary central incisor with a flared root canal. There were no significant differences between the favorable and non-favorable fracture when FRC post systems were used to restored a maxillary central incisor with a flared root canal.

    Matched MeSH terms: Stress, Mechanical
  11. Awang MA, Firdaus MA, Busra MB, Chowdhury SR, Fadilah NR, Wan Hamirul WK, et al.
    Biomed Mater Eng, 2014;24(4):1715-24.
    PMID: 24948455 DOI: 10.3233/BME-140983
    Earlier studies in our laboratory demonstrated that collagen extracted from ovine tendon is biocompatible towards human dermal fibroblast. To be able to use this collagen as a scaffold in skin tissue engineering, a mechanically stronger scaffold is required that can withstand manipulation before transplantation. This study was conducted to improve the mechanical strength of this collagen sponge using chemical crosslinkers, and evaluate their effect on physical, chemical and biocompatible properties. Collagen sponge was crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and glutaraldehyde (GA). Tensile test, FTIR study and mercury porosimetry were used to evaluate mechanical properties, chemical property and porosity, respectively. MTT assay was performed to evaluate the cytotoxic effect of crosslinked collagen sponge on human dermal fibroblasts. The FTIR study confirmed the successful crosslinking of collagen sponge. Crosslinking with EDC and GA significantly increased the mechanical strength of collagen sponge, with GA being more superior. Crosslinking of collagen sponge significantly reduced the porosity and the effect was predominant in GA-crosslinked collagen sponge. The GA-crosslinked collagen showed significantly lower, 60% cell viability towards human dermal fibroblasts compared to that of EDC-crosslinked collagen, 80% and non-crosslinked collagen, 100%. Although the mechanical strength was better when using GA but the more toxic effect on dermal fibroblast makes EDC a more suitable crosslinker for future skin tissue engineering.
    Matched MeSH terms: Stress, Mechanical
  12. Baharuddin MY, Salleh ShH, Zulkifly AH, Lee MH, Noor AM, A Harris AR, et al.
    PMID: 24484753 DOI: 10.1186/1471-2474-15-30
    Minimal available information concerning hip morphology is the motivation for several researchers to study the difference between Asian and Western populations. Current use of a universal hip stem of variable size is not the best option for all femur types. This present study proposed a new design process of the cementless femoral stem using a three dimensional model which provided more information and accurate analysis compared to conventional methods.
    Matched MeSH terms: Stress, Mechanical
  13. Purmal K, Sukumaran P
    Aust Orthod J, 2010 Nov;26(2):184-8.
    PMID: 21175030
    To investigate the shear bond strengths of buccal tubes and to determine the sites of failure.
    Matched MeSH terms: Stress, Mechanical
  14. Sia S, Shibazaki T, Koga Y, Yoshida N
    Am J Orthod Dentofacial Orthop, 2009 Jan;135(1):36-41.
    PMID: 19121498 DOI: 10.1016/j.ajodo.2007.01.034
    This study was designed to determine the optimum vertical height of the retraction force on the power arm that is required for efficient anterior tooth retraction during space closure with sliding mechanics.
    Matched MeSH terms: Stress, Mechanical
  15. Al-Makramani BMA, Razak AAA, Abu-Hassan MI
    J Prosthodont, 2008 Feb;17(2):120-124.
    PMID: 18047490 DOI: 10.1111/j.1532-849X.2007.00270.x
    PURPOSE: The current study investigated the effect of different luting agents on the fracture resistance of Procera AllCeram copings.

    METHODS: Six master dies were duplicated from the prepared maxillary first premolar tooth using nonprecious metal alloy (Wiron 99). Thirty copings (Procera AllCeram) of 0.6-mm thickness were manufactured. Three types of luting media were used: zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and dual-cured composite resin cement (Panavia F). Ten copings were cemented with each type. Two master dies were used for each group, and each of them was used to lute five copings. All groups were cemented according to manufacturer's instructions and received a static load of 5 kg during cementation. After 24 hours of distilled water storage at 37 degrees C, the copings were vertically compressed using a universal testing machine at a crosshead speed of 1 mm/min.

    RESULTS: ANOVA revealed significant differences in the load at fracture among the three groups (p < 0.001). The fracture strength results showed that the mean fracture strength of zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and resin luting cement (Panavia F) were 1091.9 N, 784.8 N, and 1953.5 N, respectively.

    CONCLUSION: Different luting agents have an influence on the fracture resistance of Procera AllCeram copings.

    Matched MeSH terms: Stress, Mechanical
  16. Memon MS, Yunus N, Razak AA
    Int J Prosthodont, 2001 May-Jun;14(3):214-8.
    PMID: 11484567
    PURPOSE: The impact strength and the flexural properties of denture base materials are of importance in predicting their clinical performance upon sudden loading. This study compares the impact and transverse strengths and the flexural modulus of three denture base polymers.
    MATERIALS AND METHODS: The investigation included a relatively new microwave-polymerized polyurethane-based denture material processed by an injection-molding technique, a conventional microwave-polymerized denture material, and a heat-polymerized compression-molded poly(methyl methacrylate) (PMMA) denture material. Impact strength was determined using a Charpy-type impact tester. The transverse strength and the flexural modulus were assessed with a three-point bending test. The results were subjected to statistical analysis using a one-way analysis of variance and the Scheffé test for comparison.
    RESULTS: The impact strength of the microwave-polymerized injection-molded polymer was 6.3 kl/m2, while its flexural strength was 66.2 MPa. These values were lower than those shown by the two compression-molded PMMA-based polymers. The differences were statistically significant. The flexural modulus of the new denture material was 2,832 MPa, which was higher than the conventional heat-polymerized polymer but was comparable to the other microwave-polymerized PMMA-based polymer. The difference in the flexural modulus was statistically significant.
    CONCLUSION: In terms of the impact and flexural strengths, the new microwave-polymerized, injection-molded, polyurethane-based polymer offered no advantage over the existing heat- and microwave-polymerized PMMA-based denture base polymers. However, it has a rigidity comparable to that of the microwave-polymerized PMMA polymer.
    Matched MeSH terms: Stress, Mechanical
  17. Sulong MZ, Setchell DJ
    J Prosthet Dent, 1991 Dec;66(6):743-7.
    PMID: 1805022
    Adhesive bond strength studies for the tray adhesive of an addition vinyl polysiloxane (President) impression material were conducted with an acrylic resin, chromium-plated brass, and plastic trays. Tensile and shear stress studies were performed on the Instron Universal testing machine. Acrylic resin specimens roughened with 80-grit silicon carbide paper exhibited appreciably higher bond strengths compared with different types of tray material and methods of surface preparation.
    Matched MeSH terms: Stress, Mechanical
  18. Khalajabadi SZ, Abu ABH, Ahmad N, Yajid MAM, Hj Redzuan NB, Nasiri R, et al.
    J Mech Behav Biomed Mater, 2018 Jan;77:360-374.
    PMID: 28985616 DOI: 10.1016/j.jmbbm.2017.09.032
    This study was aimed to improve of the corrosion resistance and mechanical properties of Mg/15TiO2/5HA nanocomposite by silicon and magnesium oxide coatings prepared using a powder metallurgy method. The phase evolution, chemical composition, microstructure and mechanical properties of uncoated and coated samples were characterized. Electrochemical and immersion tests used to investigate the in vitro corrosion behavior of the fabricated samples. The adhesion strength of ~36MPa for MgO and ~32MPa for Si/MgO coatings to substrate was measured by adhesion test. Fabrication a homogenous double layer coating with uniform thicknesses consisting micro-sized particles of Si as outer layer and flake-like particles of MgO as the inner layer on the surface of Mg/15TiO2/5HA nanocomposite caused the corrosion resistance and ductility increased whereas the ultimate compressive stress decreased. However, after immersion in SBF solution, Si/MgO-coated sample indicates the best mechanical properties compared to those of the uncoated and MgO-coated samples. The increase of cell viability percentage of the normal human osteoblast (NHOst) cells indicates the improvement in biocompatibility of Mg/15TiO2/5HA nanocomposite by Si/MgO coating.
    Matched MeSH terms: Stress, Mechanical
  19. Gangoda SVS, Avadhanam B, Jufri NF, Sohn EH, Butlin M, Gupta V, et al.
    Sci Rep, 2018 01 26;8(1):1689.
    PMID: 29374229 DOI: 10.1038/s41598-018-20117-6
    Amyloid β (Aβ) deposition is a hallmark of Alzheimer's disease (AD). Vascular modifications, including altered brain endothelial cell function and structural viability of the blood-brain barrier due to vascular pulsatility, are implicated in AD pathology. Pulsatility of phenomena in the cerebral vasculature are often not considered in in vitro models of the blood-brain barrier. We demonstrate, for the first time, that pulsatile stretch of brain vascular endothelial cells modulates amyloid precursor protein (APP) expression and the APP processing enzyme, β-secretase 1, eventuating increased-Aβ generation and secretion. Concurrent modulation of intercellular adhesion molecule 1 and endothelial nitric oxide synthase (eNOS) signaling (expression and phosphorylation of eNOS) in response to pulsatile stretch indicates parallel activation of endothelial inflammatory pathways. These findings mechanistically support vascular pulsatility contributing towards cerebral Aβ levels.
    Matched MeSH terms: Stress, Mechanical
  20. Makinejad MD, Abu Osman NA, Abu Bakar Wan Abas W, Bayat M
    Clinics (Sao Paulo), 2013 Sep;68(9):1180-8.
    PMID: 24141832 DOI: 10.6061/clinics/2013(09)02
    This study provides an experimental and finite element analysis of knee-joint structure during extended-knee landing based on the extracted impact force, and it numerically identifies the contact pressure, stress distribution and possibility of bone-to-bone contact when a subject lands from a safe height.
    Matched MeSH terms: Stress, Mechanical
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links