Displaying publications 1 - 20 of 103 in total

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  1. Abubakar Z, Salema AA, Ani FN
    Bioresour Technol, 2013 Jan;128:578-85.
    PMID: 23211483 DOI: 10.1016/j.biortech.2012.10.084
    A new technique to pyrolyse biomass in microwave (MW) system is presented in this paper to solve the problem of bio-oil deposition. Pyrolysis of oil palm shell (OPS) biomass was conducted in 800 W and 2.45 GHz frequency MW system using an activated carbon as a MW absorber. The temperature profile, product yield and the properties of the products were found to depend on the stirrer speed and MW absorber percentage. The highest bio-oil yield of 28 wt.% was obtained at 25% MW absorber and 50 rpm stirrer speed. Bio-char showed highest calorific value of the 29.5 MJ/kg at 50% MW absorber and 100 rpm stirrer speed. Bio-oil from this study was rich in phenol with highest detected as 85 area% from the GC-MS results. Thus, OPS bio-oil can become potential alternative to petroleum-based chemicals in various phenolic based applications.
    Matched MeSH terms: Equipment Failure Analysis
  2. Afshar R, Fong TS, Latifi MH, Kanthan SR, Kamarul T
    J Hand Surg Eur Vol, 2012 Jun;37(5):396-401.
    PMID: 22019989 DOI: 10.1177/1753193411424557
    The use of bicortical screws to fix metacarpal fractures has been suggested to provide no added biomechanical advantage over unicortical screw fixation. However, this was only demonstrated in static loading regimes, which may not be representative of biological conditions. The present study was done to determine whether similar outcomes are obtained when cyclic loading is applied. Transverse midshaft osteotomies were created in 20 metacarpals harvested from three cadavers. Fractures were stabilised using 2.0 mm mini fragment plates fixed with either bicortical or unicortical screw fixation. These fixations were tested to failure with a three-point bending cyclic loading protocol using an electromechanical microtester and a 1 kN load cell. The mean load to failure was 370 N (SD 116) for unicortical fixation and 450 N (SD 135) for bicortical fixation. Significant differences between these two constructs were observed. A biomechanical advantage was found when using bicortical screws in metacarpal fracture plating.
    Matched MeSH terms: Equipment Failure Analysis
  3. Ahmad F, Yusof AP, Bainbridge M, Ab Ghani S
    Biosens Bioelectron, 2008 Jul 15;23(12):1862-8.
    PMID: 18440218 DOI: 10.1016/j.bios.2008.03.006
    The mechanisms involving insulin and anti-hypertensive drugs regulation for in vivo cerebral glucose metabolism are not well-understood. This might be due to lack of direct means of measuring cerebral glucose. It is known that the continuous delivery of glucose to the brain is critical for its normal metabolic function. In this study, we report the effect of insulin and anti-hypertensive drugs on glucose level in the striatum of rats. The rats were divided into two groups, i.e. hyperglycemia (14.8+/-0.3mM plasma glucose) and diabetic (10.8+/-0.2mM plasma glucose). A custom-built glucose microsensor was implanted at coordinates A/P 1.0 from bregma, M/L +2.5 and D/V -5.0 (from dura) in the striatum. The amperometric response obtained at +0.23 V vs. Ag|AgCl corresponded to the glucose level in striatum. By varying the concentrations of protaminc zinc insulin infused into the rats, striatum glucose level was found to remain constant throughout, i.e. 9.8+/-0.1 and 4.7+/-0.1mM for hyperglycemic rats and for diabetic rats, respectively. However, infusion of valsartan and felodipine has lowered the striatum glucose level significantly. These findings agreed with the hypothesis that suggested striatum glucose uptake do not depend on insulin but is clearly dependant on anti-hypertensive drugs administration.
    Matched MeSH terms: Equipment Failure Analysis
  4. Ahmad H, Thambiratnam K, Zulkifli AZ, Lawrence A, Jasim AA, Kunasekaran W, et al.
    Sensors (Basel), 2013 Sep 30;13(10):13276-88.
    PMID: 24084118 DOI: 10.3390/s131013276
    An efficient and low cost optical method for directly measuring the concentration of homogenous biological solutes is proposed and demonstrated. The proposed system operates by Fresnel reflection, with a flat-cleaved single-mode fiber serving as the sensor probe. A laser provides a 12.9 dBm sensor signal at 1,550 nm, while a computer-controlled optical power meter measures the power of the signal returned by the probe. Three different mesenchymal stem cell (MSC) lines were obtained, sub-cultured and trypsinized daily over 9 days. Counts were measured using a haemocytometer and the conditioned media (CM) was collected daily and stored at -80 °C. MSCs release excretory biomolecules proportional to their growth rate into the CM, which changes the refractive index of the latter. The sensor is capable of detecting changes in the number of stem cells via correlation to the change in the refractive index of the CM, with the measured power loss decreasing approximately 0.4 dB in the CM sample per average 1,000 cells in the MSC subculture. The proposed system is highly cost-effective, simple to deploy, operate, and maintain, is non-destructive, and allows reliable real-time measurement of various stem cell proliferation parameters.
    Matched MeSH terms: Equipment Failure Analysis
  5. Ajiya M, Mahdi MA, Al-Mansoori MH, Hitam S, Mokhtar M
    Opt Express, 2009 Apr 13;17(8):5944-52.
    PMID: 19365413
    We experimentally demonstrate a simple widely tunable multiwavelength Brillouin/Erbium fiber laser that can be tuned over the entire C-band, thereby greatly improving the tuning range limitation faced by the previous Brillouin-erbium fiber laser architectures. Tuning range of 39 nm from 1527 nm to 1566 nm, which is only limited by the amplification bandwidth of the erbium gain was successfully achieved. At Brillouin pump wavelength of 1550 nm and 1480 nm laser pump and Brillouin pump powers of 130 mW and 2 mW respectively, all the generated output channels have peak power above 0 dBm, with the first output channel having a peak power of 8.52 dBm. The experimental set up that consists of only 4 optical components, is simple, devoid of the complex structure employed previously to enhance the tunability and feedback mechanism normally associated with multiwavelength Brillouin-erbium fiber laser sources. The generated output channels are stable, rigidly separated by 10 GHz (0.08 nm).
    Matched MeSH terms: Equipment Failure Analysis
  6. Akbari E, Buntat Z, Shahraki E, Parvaz R, Kiani MJ
    J Biomater Appl, 2016 Jan;30(6):677-85.
    PMID: 26024896 DOI: 10.1177/0885328215585682
    Graphene is another allotrope of carbon with two-dimensional monolayer honeycomb. Owing to its special characteristics including electrical, physical and optical properties, graphene is known as a more suitable candidate compared to other materials to be used in the sensor application. It is possible, moreover, to use biosensor by using electrolyte-gated field effect transistor based on graphene (GFET) to identify the alterations in charged lipid membrane properties. The current article aims to show how thickness and charges of a membrane electric can result in a monolayer graphene-based GFET while the emphasis is on the conductance variation. It is proposed that the thickness and electric charge of the lipid bilayer (LLP and QLP) are functions of carrier density, and to find the equation relating these suitable control parameters are introduced. Artificial neural network algorithm as well as support vector regression has also been incorporated to obtain other models for conductance characteristic. The results comparison between analytical models, artificial neural network and support vector regression with the experimental data extracted from previous work show an acceptable agreement.
    Matched MeSH terms: Equipment Failure Analysis
  7. Al-Asadi HA, Abu Bakar MH, Al-Mansoori MH, Adikan FR, Mahdi MA
    Opt Express, 2011 Dec 5;19(25):25741-8.
    PMID: 22273966 DOI: 10.1364/OE.19.025741
    This paper details a theoretical modeling of Brillouin ring fiber laser which incorporates the interaction between multiple Brillouin Stokes signals. The ring cavity was pumped at several Brillouin pump (BP) powers and the output was measured through an optical coupler with various coupling ratios. The first-order Brillouin Stokes signal was saturated with the presence of the second-order Stokes signal in the cavity as a result of energy transfer between them. The outcome of the study found that the optimum point for the first-order Stokes wave performance is at laser power reduction of 10%. Resultantly, at the optimum output coupling ratio of 90%, the BFL was able to produce 19.2 mW output power at BP power and Brillouin threshold power of 60 and 21.3 mW respectively. The findings also exhibited the feasibility of the theoretical models application to ring-type Brillouin fiber laser of various design parameters.
    Matched MeSH terms: Equipment Failure Analysis
  8. Al-Asadi HA, Al-Mansoori MH, Hitam S, Saripan MI, Mahdi MA
    Opt Express, 2011 Jan 31;19(3):1842-53.
    PMID: 21368999 DOI: 10.1364/OE.19.001842
    We implement a particle swarm optimization (PSO) algorithm to characterize stimulated Brillouin scattering phenomena in optical fibers. The explicit and strong dependence of the threshold exponential gain on the numerical aperture, the pump laser wavelength and the optical loss coefficient are presented. The proposed PSO model is also evaluated with the localized, nonfluctuating source model and the distributed (non-localized) fluctuating source model. Using our model, for fiber lengths from 1 km to 29 km, the calculated threshold exponential gain of stimulated Brillouin scattering is gradually decreased from 17.4 to 14.6 respectively. The theoretical results of Brillouin threshold power predicted by the proposed PSO model show a good agreement with the experimental results for different fiber lengths from 1 km to 12 km.
    Matched MeSH terms: Equipment Failure Analysis
  9. Al-Fakih EA, Osman NA, Eshraghi A, Adikan FR
    Sensors (Basel), 2013 Aug 12;13(8):10348-57.
    PMID: 23941909 DOI: 10.3390/s130810348
    This study presents the first investigation into the capability of fiber Bragg grating (FBG) sensors to measure interface pressure between the stump and the prosthetic sockets of a trans-tibial amputee. FBG element(s) were recoated with and embedded in a thin layer of epoxy material to form a sensing pad, which was in turn embedded in a silicone polymer material to form a pressure sensor. The sensor was tested in real time by inserting a heavy-duty balloon into the socket and inflating it by using an air compressor. This test was conducted to examine the sensitivity and repeatability of the sensor when subjected to pressure from the stump of the trans-tibial amputee and to mimic the actual environment of the amputee's Patellar Tendon (PT) bar. The sensor exhibited a sensitivity of 127 pm/N and a maximum FSO hysteresis of around ~0.09 in real-time operation. Very good reliability was achieved when the sensor was utilized for in situ measurements. This study may lead to smart FBG-based amputee stump/socket structures for pressure monitoring in amputee socket systems, which will result in better-designed prosthetic sockets that ensure improved patient satisfaction.
    Matched MeSH terms: Equipment Failure Analysis
  10. Al-Mansoori MH, Mahdi MA
    Opt Express, 2008 May 26;16(11):7649-54.
    PMID: 18545472
    We demonstrate an enhanced multiwavelength L-band Brillouin-erbium fiber laser (BEFL), in which the Brillouin pump is pre-amplified before entering the single-mode fiber. The Brillouin pump pre-amplification provided by the Erbium-doped fiber has created higher intensity of Brillouin Stokes line generated in the single-mode fiber that leads to the homogenous gain saturation. Thus the built-up of self-lasing cavity modes is suppressed in a wider wavelength range. In contrary to the conventional linear-cavity BEFL, the number of output channels is enhanced within the same tuning range.
    Matched MeSH terms: Equipment Failure Analysis
  11. Alajerami YS, Hashim S, Ramli AT, Saleh MA, Saripan MI, Alzimami K, et al.
    Appl Radiat Isot, 2013 Aug;78:21-5.
    PMID: 23644162 DOI: 10.1016/j.apradiso.2013.03.095
    New glasses Li2CO3-K2CO3-H3BO3 (LKB) co-doped with CuO and MgO, or with TiO2 and MgO, were synthesized by the chemical quenching technique. The thermoluminescence (TL) responses of LKB:Cu,Mg and LKB:Ti,Mg irradiated with 6 MV photons or 6 MeV electrons were compared in the dose range 0.5-4.0 Gy. The standard commercial dosimeter LiF:Mg,Ti (TLD-100) was used to calibrate the TL reader and as a reference in comparison of the TL properties of the new materials. The dependence of the responses of the new materials on (60)Co dose is linear in the range of 1-1000 Gy. The TL yields of both of the co-doped glasses and TLD-100 are greater for electron irradiation than for photon irradiation. The TL sensitivity of LKB:Ti,Mg is 1.3 times higher than the sensitivity of LKB:Cu,Mg and 12 times less than the sensitivity of TLD-100. The new TL dosimetric materials have low effective atomic numbers, good linearity of the dose responses, excellent signal reproducibility, and a simple glow curve structure. This combination of properties makes them suitable for radiation dosimetry.
    Matched MeSH terms: Equipment Failure Analysis
  12. Alanazi A, Alkhorayef M, Alzimami K, Jurewicz I, Abuhadi N, Dalton A, et al.
    Appl Radiat Isot, 2016 Nov;117:106-110.
    PMID: 26777569 DOI: 10.1016/j.apradiso.2016.01.001
    Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.
    Matched MeSH terms: Equipment Failure Analysis
  13. Alashrah S, Kandaiya S, Lum LS, Cheng SK
    Z Med Phys, 2013 Dec;23(4):270-8.
    PMID: 24113373 DOI: 10.1016/j.zemedi.2013.09.001
    One of the factors which influence the spatial resolution of a 2D detector array is the size of the single detector, another the transport of the secondary electrons from the walls into the measuring volume. In this study, the single ion chamber dose response function of an I'mRT MatriXX array was determined by comparison between slit beam dose profiles measured with the array and with EBT2 radiochromic film in a solid water-equivalent phantom at a shallow depth of 0.5cm and at a depth of 5cm beyond the depth dose maximum for a 6 MV photon beam. The dose response functions were obtained using two methods, the best fit method and the deconvolution method. At the shallow depth, a Lorentz function and at 5cm depth a Gaussian function, both with the same FWHM of 7.4mm within limits of uncertainty, were identified as the best suited dose response functions of the 4.5mm diameter single array chamber. These dose response functions were then tested on various dose profiles whose true shape had been determined with EBT2 film and with the IC03 ionization chamber. By convolving these with the Lorentz kernel (at shallow depth) and the Gaussian kernel (at 5cm depth) the signal profiles measured with the I'mRT MatriXX array were closely approximated. Thus, the convolution of TPS-calculated dose profiles with these dose response functions can minimize the differences between calculation and measurement which occur due to the limited spatial resolution of the I'mRT MatriXX detector.
    Matched MeSH terms: Equipment Failure Analysis
  14. Alawiah A, Bauk S, Marashdeh MW, Nazura MZ, Abdul-Rashid HA, Yusoff Z, et al.
    Appl Radiat Isot, 2015 Oct;104:197-202.
    PMID: 26188687 DOI: 10.1016/j.apradiso.2015.07.011
    In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.
    Matched MeSH terms: Equipment Failure Analysis
  15. Ali S, Osman NA, Mortaza N, Eshraghi A, Gholizadeh H, Wan Abas WA
    Clin Biomech (Bristol, Avon), 2012 Nov;27(9):943-8.
    PMID: 22795863 DOI: 10.1016/j.clinbiomech.2012.06.004
    The interface pressure between the residual limb and prosthetic socket has a significant effect on an amputee's satisfaction and comfort. Liners provide a comfortable interface by adding a soft cushion between the residual limb and the socket. The Dermo and the Seal-In X5 liner are two new interface systems and, due to their relative infancy, very little are known about their effect on patient satisfaction. The aim of this study was to compare the interface pressure with these two liners and their effect on patient satisfaction.
    Matched MeSH terms: Equipment Failure Analysis
  16. Alizadeh M, Kadir MR, Fadhli MM, Fallahiarezoodar A, Azmi B, Murali MR, et al.
    J Orthop Res, 2013 Sep;31(9):1447-54.
    PMID: 23640802 DOI: 10.1002/jor.22376
    Posterior instrumentation is a common fixation method used to treat thoracolumbar burst fractures. However, the role of different cross-link configurations in improving fixation stability in these fractures has not been established. A 3D finite element model of T11-L3 was used to investigate the biomechanical behavior of short (2 level) and long (4 level) segmental spine pedicle screw fixation with various cross-links to treat a hypothetical L1 vertebra burst fracture. Three types of cross-link configurations with an applied moment of 7.5 Nm and 200 N axial force were evaluated. The long construct was stiffer than the short construct irrespective of whether the cross-links were used (p < 0.05). The short constructs showed no significant differences between the cross-link configurations. The XL cross-link provided the highest stiffness and was 14.9% stiffer than the one without a cross-link. The long construct resulted in reduced stress to the adjacent vertebral bodies and screw necks, with 66.7% reduction in bending stress on L2 when the XL cross-link was used. Thus, the stability for L1 burst fracture fixation was best achieved by using long segmental posterior instrumentation constructs and an XL cross-link configuration. Cross-links did not improved stability when a short structure was used.
    Matched MeSH terms: Equipment Failure Analysis
  17. Amjad RJ, Sahar MR, Dousti MR, Ghoshal SK, Jamaludin MN
    Opt Express, 2013 Jun 17;21(12):14282-90.
    PMID: 23787617 DOI: 10.1364/OE.21.014282
    We report significant enhancements in Er(3+) luminescence as well as in Raman intensity in silver nanoparticles embedded zinc-tellurite glass. Surface enhanced Raman scattering effect is highlighted for the first time in tellurite glass containing silver NPs resulting in an enhanced Raman signal (~10 times). SAED manifest the growth of Ag(0) nanoparticles along the (111) and (200) crystallographic planes having average diameter in the range 14-36 nm. Surface plasmon resonance bands are observed in the range 484-551 nm. Furthermore, four prominent photoluminescence bands undergo significant enhancements up to 3 times. The enhancement is majorly attributed to the local field effect of silver NPs.
    Matched MeSH terms: Equipment Failure Analysis
  18. An J, Nam J, Kim B, Lee HS, Kim BH, Chang IS
    Bioresour Technol, 2015 Aug;190:175-81.
    PMID: 25941759 DOI: 10.1016/j.biortech.2015.04.071
    The effect of two different anode-embedding orientations, lengthwise- and widthwise-embedded anodes was explored, on the performance of sediment microbial fuel cells (SMFCs) using a chessboard anode. The maximum current densities and power densities in SMFCs having lengthwise-embedded anodes (SLA1-SLA10) varied from 38.2mA/m(2) to 121mA/m(2) and from 5.5mW/m(2) to 20mW/m(2). In comparison, the maximum current densities and maximum power densities in SMFCs having anodes widthwise-embedded between 0cm to 8cm (SWA2-SWA5) increased from 82mA/m(2) to 140mA/m(2) and from 14.7mW/m(2) to 31.1mW/m(2) as the anode depth became deeper. Although there was a difference in the performance among SWA5-SWA10, it was considered negligible. Hence, it is concluded that it is important to embed anodes widthwise at the specific anode depths, in order to improve of SMFC performance. Chessboard anode used in this work could be a good option for the determination of optimal anode depths.
    Matched MeSH terms: Equipment Failure Analysis
  19. Azlan CA, Ng KH, Anandan S, Nizam MS
    Australas Phys Eng Sci Med, 2006 Sep;29(3):278-80.
    PMID: 17058591
    Illuminance level in the softcopy image viewing room is a very important factor to optimize productivity in radiological diagnosis. In today's radiological environment, the illuminance measurements are normally done during the quality control procedure and performed annually. Although the room is equipped with dimmer switches, radiologists are not able to decide the level of illuminance according to the standards. The aim of this study is to develop a simple real-time illuminance detector system to assist the radiologists in deciding an adequate illuminance level during radiological image viewing. The system indicates illuminance in a very simple visual form by using light emitting diodes. By employing the device in the viewing room, illuminance level can be monitored and adjusted effectively.
    Matched MeSH terms: Equipment Failure Analysis
  20. Bahadoran M, Noorden AF, Chaudhary K, Mohajer FS, Aziz MS, Hashim S, et al.
    Sensors (Basel), 2014;14(7):12885-99.
    PMID: 25046015 DOI: 10.3390/s140712885
    A new photonics biosensor configuration comprising a Double-side Ring Add-drop Filter microring resonator (DR-ADF) made from SiO2-TiO2 material is proposed for the detection of Salmonella bacteria (SB) in blood. The scattering matrix method using inductive calculation is used to determine the output signal's intensities in the blood with and without presence of Salmonella. The change in refractive index due to the reaction of Salmonella bacteria with its applied antibody on the flagellin layer loaded on the sensing and detecting microresonator causes the increase in through and dropper port's intensities of the output signal which leads to the detection of SB in blood. A shift in the output signal wavelength is observed with resolution of 0.01 nm. The change in intensity and shift in wavelength is analyzed with respect to the change in the refractive index which contributes toward achieving an ultra-high sensitivity of 95,500 nm/RIU which is almost two orders higher than that of reported from single ring sensors and the limit of detection is in the order of 1 × 10(-8) RIU. In applications, such a system can be employed for a high sensitive and fast detection of bacteria.
    Matched MeSH terms: Equipment Failure Analysis/methods
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