Displaying publications 1 - 20 of 39 in total

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  1. Al-Raad AA, Hanafiah MM
    J Environ Manage, 2021 Dec 15;300:113696.
    PMID: 34509809 DOI: 10.1016/j.jenvman.2021.113696
    Electrocoagulation (ECoag) technique has shown considerable potential as an effective method in separating different types of pollutants (including inorganic pollutants) from various sources of water at a lower cost, and that is environmentally friendly. The EC method's performance depends on several significant parameters, including current density, reactor geometry, pH, operation time, the gap between electrodes, and agitation speed. There are some challenges related to the ECoag technique, for example, energy consumption, and electrode passivation as well as its implementation at a larger scale. This review highlights the recent studies published about ECoag capacity to remove inorganic pollutants (including salts), the emerging reactors, and the effect of reactor geometry designs. In addition, this paper highlights the integration of the ECoag technique with other advanced technologies such as microwave and ultrasonic to achieve higher removal efficiencies. This paper also presents a critical discussion of the major and minor reactions of the electrocoagulation technique with several significant operational parameters, emerging designs of the ECoag cell, operating conditions, and techno-economic analysis. Our review concluded that optimizing the operating parameters significantly enhanced the efficiency of the ECoag technique and reduced overall operating costs. Electrodes geometry has been recommended to minimize the passivation phenomenon, promote the conductivity of the cell, and reduce energy consumption. In this review, several challenges and gaps were identified, and insights for future development were discussed. We recommend that future studies investigate the effect of other emerging parameters like perforated and ball electrodes on the ECoag technique.
  2. Al-Raad AA, Hanafiah MM, Naje AS, Ajeel MA
    Environ Pollut, 2020 Oct;265(Pt B):115049.
    PMID: 32599327 DOI: 10.1016/j.envpol.2020.115049
    In this study, a novel rotating anode-based reactor (RAR) was designed to investigate its effectiveness in removing dissolved salts (i.e., Br-, Cl-, TDS, and SO42-) from saline water samples. Two configurations of an impeller's rotating anode with various operation factors, such as operating time (min), rotating speed (rpm), current density (mA/cm2), temperature (°C), pH, and inter-electrode space (cm), were used in the desalination process. The total cost consumed was calculated on the basis of the energy consumption and aluminum (Al) used in the desalination. In this respect, operating costs were calculated using optimal operating conditions. Salinity was removed electrochemically from saline water through electrocoagulation (EC). Results showed that the optimal adjustments for treating saline water were carried out at the following conditions: 150 and 75 rpm rotating speeds for the impeller's rod anode and plate anode designs, respectively; 2 mA/cm2 current density (I), 1 cm2 inter-electrode space, 25 °C temperature, 10 min operation time, and pH 8. The results indicated that EC technology with impeller plates of rotating anode can be considered a very cost-effective technique for treating saline water.
  3. Lim TW, Burhainuddin M, Abbas A
    Med J Malaya, 1972 Dec;27(2):147-9.
    PMID: 4268041
  4. Lim TW, Burhainuddin M, Abbas A
    Med J Malaysia, 1972 Dec;27(2):147-149.
    PMID: 35158495
    No abstract available.
  5. Hasan A, Abbas A, Akhtar MN
    Molecules, 2011 Sep 13;16(9):7789-802.
    PMID: 22143543 DOI: 10.3390/molecules16097789
    A series of 1,3,5-triaryl-2-pyrazolines was synthesized by dissolving the corresponding 4-alkoxychalcones in glacial acetic acid containing a few drops of concentrated hydrochloric acid. This step was followed by the addition of (3,4-dimethylphenyl) hydrazaine hydrochloride. Finally the target compounds were precipitated by pouring the reaction mixture onto crushed ice. The structures of the synthesized compounds were established by physicochemical and spectroscopic methods. The 1,3,5-triaryl-2-pyrazolines bearing homologous alkoxy groups were found to possess fluorescence properties in the blue region of the visible spectrum when irradiated with ultraviolet radiation. The fluorescent behavior of these compounds was studied by UV-Vis and emission spectroscopy, performed at room temperature.
  6. Nisar A, Choon DS, Varaprasad M, Abbas AA
    Med J Malaysia, 2006 Feb;61 Suppl A:100-2.
    PMID: 17042242
    A variety of reconstructive options exist for revision of both femoral and acetabular components in total hip replacement surgery. The use of impaction bone grafting with morsellised allograft has shown promising results in revision total hip arthroplasty. It works as a biologic reconstitution of bone stock defects and provides a solid construct with stable fixation. We present a case of bilateral revision total hip arthroplasty with poor bone stock where reconstructive surgery was done by using impaction bone grafting, mesh and C-stem implants.
  7. Shahemi N, Liza S, Abbas AA, Merican AM
    J Mech Behav Biomed Mater, 2018 11;87:1-9.
    PMID: 30031358 DOI: 10.1016/j.jmbbm.2018.07.017
    A revision of a metal-on-ultra high molecular weight (UHMWPE) bearing couple for total hip replacement was performed due to aseptic loosening after 23 years in-vivo. It is a major long-term failure identified from wear generation. This study includes performing failure analysis of retrieved polyethylene acetabular cup from Zimmer Trilogy® Acetabular system. The UHMWPE acetabular cup was retrieved from a 61 years old male patient with ability to walk but limited leg movement when he presented to hospital in early 2016 with complaint left thigh pain. It was 23 years after his primary total hip replacement procedure. Surface roughness and morphology condition were measured using 3D laser microscope and Scanning Electron Microscope (SEM) to evaluate and characterize the wear features on polyethylene acetabular cup surface. ATR-Fourier Transform Infra-Red (ATR-FTIR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) were used to characterize the chemical composition of carbon-oxygen bonding, crystallinity percentage and molecular weight of the polymer liner that might changes the mechanical properties of polyethylene. Nano indentation is to measure hardness and elasticity modulus where the ratio of hardness to elastic modulus value can be reflected as the degradation of mechanical properties. A prominent difference of thickness between two regions resulted from acentric loading concentration was observed and wear rate were measured. The linear wear rate for thin side and thick side were 0.33 mm/year and 0.05 mm/year respectively. Molecular weight reduction of 57.5% and relatively low ratio of hardness to elastic modulus (3.59 × 10-3) were the indicator of major mechanical properties degradation happened on UHMWPE acetabular cup. This major degradation was contributed by oxidation and polishing wear feature accompanied with delamination, craters, ripple and cracks were the indication of extensive usage of UHMWPE from the suggested life span of acetabular cup application.
  8. Abbas AA, Guo X, Tan WH, Jalab HA
    J Med Syst, 2014 Aug;38(8):80.
    PMID: 24957396 DOI: 10.1007/s10916-014-0080-7
    In a computerized image analysis environment, the irregularity of a lesion border has been used to differentiate between malignant melanoma and other pigmented skin lesions. The accuracy of the automated lesion border detection is a significant step towards accurate classification at a later stage. In this paper, we propose the use of a combined Spline and B-spline in order to enhance the quality of dermoscopic images before segmentation. In this paper, morphological operations and median filter were used first to remove noise from the original image during pre-processing. Then we proceeded to adjust image RGB values to the optimal color channel (green channel). The combined Spline and B-spline method was subsequently adopted to enhance the image before segmentation. The lesion segmentation was completed based on threshold value empirically obtained using the optimal color channel. Finally, morphological operations were utilized to merge the smaller regions with the main lesion region. Improvement on the average segmentation accuracy was observed in the experimental results conducted on 70 dermoscopic images. The average accuracy of segmentation achieved in this paper was 97.21 % (where, the average sensitivity and specificity were 94 % and 98.05 % respectively).
  9. Abbas AA, Merican AM, Kwan MK, Mohamad JA
    Med J Malaysia, 2006 Feb;61 Suppl A:83-7.
    PMID: 17042237
    Total knee arthroplasty is the most preferred option for treatment of severe osteoarthritis of the knee. We report the short-term outcome of 48 total knee replacements in 31 patients utilizing the Apollo Total Knee System after an average follow-up of 48 months (range 15 to 70 months). Records of all patients who underwent TKA using Apollo Total Knee System were retrospectively reviewed. Functional outcome was evaluated using visual analogue scale for pain rating and the Oxford 12-item questionnaire. Postoperative radiographs of the replaced knees were assessed by using the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Degenerative osteoarthritis was the commonest indication for TKA. The average patient's age was 63.7 years (range, 30-77 years). The mean visual analogue scale for pre- and post-operative pain was eight and zero respectively. The mean Oxford 12-item questionnaire score pre- and post-operatively was 44.8 and 16.5 respectively. Patient satisfaction was notable in 98% of the cases with an average improvement in arc of flexion of 111 degrees. There were four failures; deep infection (one) and aseptic loosening (three) giving rise to a 94% implant survivor. The short-term results of this series is comparable with or better than a number of outcome studies of the Apollo Knee System or other implants of similar design.
  10. Zyroul R, Hossain MG, Azura M, Abbas AA, Kamarul T
    Knee, 2014 Mar;21(2):557-62.
    PMID: 23473894 DOI: 10.1016/j.knee.2012.12.013
    BACKGROUND: Knee laxity measurements have been shown to be associated with some medical conditions such as chronic joint pain and collagen tissue diseases. The aim of this study was to determine the effects of demographic factors and anthropometric measures on knee laxity.
    MATERIALS AND METHODS: Data were collected from 521 visitors, staffs and students from the University Malaya Medical Centre and University of Malaya between December 2009 and May 2010. Knee laxity was measured using a KT-1000 arthrometer. Multiple regression analysis was used to find the association of knee laxity with age and anthropometric measures.
    RESULTS: Using ANOVA, knee laxity did not show significant differences among ethnic groups for both genders. The average knee laxity in men was 3.47 mm (right) and 3.49 mm (left); while in women were 3.90 mm (right) and 3.67 mm (left). Knee laxity in women was significantly higher (right knee p<0.01 and left knee p<0.05) than men. Right knee laxity of men was negatively associated with height (p<0.05) and BMI (p<0.05); also a negative association was observed between left knee laxity and BMI (p<0.05). Overweight and obese men had less knee laxity than normal weight and underweight individuals. Elderly men and women (age 55 and above) had lower knee laxity (p<0.01) than young adults (ages 21-39).
    CONCLUSION: These results suggest that age and body size are important factors in predicting knee laxity.
    KEYWORDS: Age; Anthropometric measures; Joint mobility; KT 1000; Knee laxity
  11. Teh KH, Ruben JK, Chan CK, Abbas AA
    Malays Orthop J, 2020 Jul;14(2):134-137.
    PMID: 32983389 DOI: 10.5704/MOJ.2007.022
    Avascular necrosis and non-union are two most dreaded complications of femoral neck fracture fixations. Hip replacement seems to be a simple solution for this complex problem. However, the long-term efficacy of prosthetic replacement in the young population with higher functional demand is still questionable. Femoral head preserving valgus subtrochanteric osteotomies in properly selected cases have strong support from literature. The conventional technique of valgus subtrochanteric osteotomy involves lateral based wedge resection. Alternatively, a simpler sliding oblique subtrochanteric osteotomy without any wedge removal can also be performed. We hereby describe a successful case of sliding subtrochanteric osteotomy with 135° dynamic hip screw (DHS) plate fixation in treating non-union neck of femur fracture in a young gentleman.
  12. Abd Rahim MH, Lim EJ, Hasan H, Abbas A
    J Microbiol Methods, 2019 09;164:105672.
    PMID: 31326443 DOI: 10.1016/j.mimet.2019.105672
    PURPOSE: This study aimed to assess the effect of nitrogen, salt and pre-culture conditions on the production of lovastatin in A. terreus ATCC 20542.

    METHODS: Different combinations of nitrogen sources, salts and pre-culture combinations were applied in the fermentation media and lovastatin yield was analysed chromatographically.

    RESULT: The exclusion of MnSO4 ·5H2O, CuSO4·5H2O and FeCl3·6H2O were shown to significantly improve lovastatin production (282%), while KH2PO4, MgSO4·7H2O, and NaCl and ZnSO4·7H2O were indispensable for good lovastatin production. Simple nitrogen source (ammonia) was unfavourable for morphology, growth and lovastatin production. In contrast, yeast extract (complex nitrogen source) produced the highest lovastatin yield (25.52 mg/L), while powdered soybean favoured the production of co-metabolites ((+)-geodin and sulochrin). Intermediate lactose: yeast extract (5:4) ratio produced the optimal lovastatin yield (12.33 mg/L) during pre-culture, while high (5:2) or low (5:6) lactose to yeast extract ratio produced significantly lower lovastatin yield (7.98 mg/L and 9.12 mg/L, respectively). High spore concentration, up to 107 spores/L was shown to be beneficial for lovastatin, but not for co-metabolite production, while higher spore age was shown to be beneficial for all of its metabolites.

    CONCLUSION: The findings from these investigations could be used for future cultivation of A. terreus in the production of desired metabolites.

  13. Rahim MHA, Hasan H, Harith HH, Abbas A
    Bioprocess Biosyst Eng, 2017 Dec;40(12):1753-1761.
    PMID: 28879627 DOI: 10.1007/s00449-017-1830-y
    This study investigates the effects of viscosity, friction, and sonication on the morphology and the production of lovastatin, (+)-geodin, and sulochrin by Aspergillus terreus ATCC 20542. Sodium alginate and gelatine were used to protect the fungal pellet from mechanical force by increasing the media viscosity. Sodium alginate stimulated the production of lovastatin by up to 329.0% and sulochrin by 128.7%, with inhibitory effect on (+)-geodin production at all concentrations used. However, the use of gelatine to increase viscosity significantly suppressed lovastatin, (+)-geodin, and sulochrin's production (maximum reduction at day 9 of 42.7, 60.8, and 68.3%, respectively), which indicated that the types of chemical play a major role in metabolite production. Higher viscosity increased both pellet biomass and size in all conditions. Friction significantly increased (+)-geodin's titre by 1527.5%, lovastatin by 511.1%, and sulochrin by 784.4% while reducing pellet biomass and size. Conversely, sonication produced disperse filamentous morphology with significantly lower metabolites. Sodium alginate-induced lovastatin and sulochrin production suggest that these metabolites are not affected by viscosity; rather, their production is affected by the specific action of certain chemicals. In contrast, low viscosity adversely affected (+)-geodin's production, while pellet disintegration can cause a significant production of (+)-geodin.
  14. Nam HY, Pingguan-Murphy B, Amir Abbas A, Mahmood Merican A, Kamarul T
    Biomech Model Mechanobiol, 2015 Jun;14(3):649-63.
    PMID: 25351891 DOI: 10.1007/s10237-014-0628-y
    It has been previously demonstrated that mechanical stimuli are important for multipotent human bone marrow-derived mesenchymal stromal cells (hMSCs) to maintain good tissue homeostasis and even to enhance tissue repair processes. In tendons, this is achieved by promoting the cellular proliferation and tenogenic expression/differentiation. The present study was conducted to determine the optimal loading conditions needed to achieve the best proliferation rates and tenogenic differentiation potential. The effects of mechanical uniaxial stretching using different rates and strains were performed on hMSCs cultured in vitro. hMSCs were subjected to cyclical uniaxial stretching of 4, 8 or 12 % strain at 0.5 or 1 Hz for 6, 24, 48 or 72 h. Cell proliferation was analyzed using alamarBlue[Formula: see text] assay, while hMSCs differentiation was analyzed using total collagen assay and specific tenogenic gene expression markers (type I collagen, type III collagen, decorin, tenascin-C, scleraxis and tenomodulin). Our results demonstrate that the highest cell proliferation is observed when 4 % strain [Formula: see text] 1 Hz was applied. However, at 8 % strain [Formula: see text] 1 Hz loading, collagen production and the tenogenic gene expression were highest. Increasing strain or rates thereafter did not demonstrate any significant increase in both cell proliferation and tenogenic differentiation. In conclusion, our results suggest that 4 % [Formula: see text] 1 Hz cyclic uniaxial loading increases cell proliferation, but higher strains are required for superior tenogenic expressions. This study suggests that selected loading regimes will stimulate tenogenesis of hMSCs.
  15. Abbas A, Nazir H, Naseer MM, Bolte M, Hussain S, Hafeez N, et al.
    PMID: 24177882 DOI: 10.1016/j.saa.2013.10.023
    A series of new pyrazoline derivatives (1b-4c) bearing N-acyl arms and nine to twelve carbon long alkoxy side chains was synthesized and characterized on the basis of spectroscopic data and microanalysis. The nature of self-assembly to understand the interplay of alkoxy chain crystallization and various supramolecular interactions was investigated using single crystal X-ray diffraction studies. Interesting self-assembled supramolecular structures of 1b and 4c were observed in the crystal lattice owing to various CH⋯O, H⋯H, CH⋯π, lonepair⋯π and π⋯π interactions. Further, all the synthesized compounds (1b-4c) were screened for their in vitro antifungal and anti-inflammatory activities. Compounds 2b, 3b, 2c and 3c showed significant to moderate antifungal activity against Microsporum canis whereas most of the other compounds were found inactive against all the five tested fungal strains. Good anti-inflammatory activity was observed for compounds 1b with IC50 value 331 μM compared to 273 μM for Indomethacine, a standard reference drug. The bio-activity data demonstrates the relationship between lipophilicity, solubility and bioavailability.
  16. Lee SY, Pereira BP, Yusof N, Selvaratnam L, Yu Z, Abbas AA, et al.
    Acta Biomater, 2009 Jul;5(6):1919-25.
    PMID: 19289306 DOI: 10.1016/j.actbio.2009.02.014
    A poly(vinyl alcohol) (PVA) hydrogel composite scaffold containing N,O-carboxymethylated chitosan (NOCC) was tested to assess its potential as a scaffold for cartilage tissue engineering in a weight-bearing environment. The mechanical properties under unconfined compression for different hydration periods were investigated. The effect of supplementing PVA with NOCC (20wt.% PVA:5vol.% NOCC) produced a porosity of 43.3% and this was compared against a non-porous PVA hydrogel (20g PVA: 100ml of water, control). Under non-hydrated conditions, the porous PVA-NOCC hydrogel behaved in a similar way to the control non-porous PVA hydrogel, with similar non-linear stress-strain response under unconfined compression (0-30% strain). After 7days' hydration, the porous hydrogel demonstrated a reduced stiffness (0.002kPa, at 25% strain), resulting in a more linear stiffness relationship over a range of 0-30% strain. Poisson's ratio for the hydrated non-porous and porous hydrogels ranged between 0.73 and 1.18, and 0.76 and 1.33, respectively, suggesting a greater fluid flow when loaded. The stress relaxation function for the porous hydrogel was affected by the hydration period (from 0 to 600s); however the percentage stress relaxation regained by about 95%, after 1200s for all hydration periods assessed. No significant differences were found between the different hydration periods between the porous hydrogels and control. The calculated aggregate modulus, H(A), for the porous hydrogel reduced drastically from 10.99kPa in its non-hydrated state to about 0.001kPa after 7days' hydration, with the calculated shear modulus reducing from 30.92 to 0.14kPa, respectively. The porous PVA-NOCC hydrogel conformed to a biphasic, viscoelastic model, which has the desired properties required for any scaffold in cartilage tissue engineering.
  17. Mohamad JA, Kwan MK, Merican AM, Abbas AA, Kamari ZH, Hisa MK, et al.
    Med J Malaysia, 2004 Dec;59 Suppl F:3-7.
    PMID: 15941153
    We report our early experience of 20 cases of metal on metal articulation total hip arthroplasty in 19 young patients. Avascular necrosis of the femoral head (63%) was the commonest diagnosis for patients undergoing this procedure, followed by osteoarthritis (21%). In general, most of the patients were young and physically active with an average age of 43.1 years (range, 25 to 58 years). The average follow-up period was 18 months (range, 7 to 46 months). The mean total Harris Hip Score preoperatively and at final follow-up was 31 points and 89 points respectively. The mean total Pain Score improved from an average of 11.5 to 41.1 points at final follow-up. Sixteen (84%) of the patients had a good to excellent hip score. There was one dislocation, which stabilized after reduction and conservative management. One case of early infection underwent a two-staged revision.
  18. Agi A, Junin R, Arsad A, Abbas A, Gbadamosi A, Azli NB, et al.
    PLoS One, 2019;14(9):e0220778.
    PMID: 31560699 DOI: 10.1371/journal.pone.0220778
    Ascorbic acid was used for the first time to synthesize cellulose nanoparticles (CNP) extracted from okra mucilage. The physical properties of the CNP including their size distribution, and crystalline structures were investigated. The rheological properties of the cellulose nanofluid (CNF) were compared with the bulk okra mucilage and commercial polymer xanthan. The interfacial properties of the CNF at the interface of oil-water (O/W) system were investigated at different concentrations and temperatures. The effects of the interaction between the electrolyte and ultrasonic were determined. Core flooding experiment was conducted at reservoir condition to justify the effect of the flow behaviour and disperse phase behaviour of CNF on additional oil recovery. The performance of the CNF was compared to conventional EOR chemical. The combined method of ultrasonic, weak-acid hydrolysis and nanoprecipitation were effective in producing spherical and polygonal nanoparticles with a mean diameter of 100 nm, increased yield of 51% and preserved crystallinity respectively. The zeta potential result shows that the CNF was stable, and the surface charge signifies long term stability of the fluid when injected into oil field reservoirs. The CNF, okra and xanthan exhibited shear-thinning and pseudoplastic behaviour. The IFT decreased with increase in concentration of CNF, electrolyte and temperature. The pressure drop data confirmed the stability of CNF at 120°C and the formation of oil bank was enough to increase the oil recovery by 20%. CNF was found to be very effective in mobilizing residual oil at high-temperature high-pressure (HTHP) reservoir condition. The energy and cost estimations have shown that investing in ultrasonic-assisted weak-acid hydrolysis is easier, cost-effective, and can reduce energy consumption making the method economically advantageous compared to conventional methods.
  19. Shahzad F, Du J, Khan I, Fateh A, Shahbaz M, Abbas A, et al.
    PMID: 32679748 DOI: 10.3390/ijerph17145102
    Historically, infectious diseases have been the leading cause of human psychosomatic strain and death tolls. This research investigated the recent threat of COVID-19 contagion, especially its impact among frontline paramedics treating patients with COVID-19, and their perception of self-infection, which ultimately increases their agonistic behaviour. Based on the stressor-strain-outcome paradigm, a research model was proposed and investigated using survey-based data through a structured questionnaire. The results found that the perceived threat of COVID-19 contagion (emotional and cognitive threat) was positively correlated with physiological anxiety, depression, and emotional exhaustion, which led toward agonistic behaviour. Further, perceived social support was a key moderator that negatively affected the relationships between agonistic behaviour and physiological anxiety, depression, and emotional exhaustion. These findings significantly contributed to the current literature concerning COVID-19 and pandemic-related effects on human behaviour. This study also theorized the concept of human agonistic behaviour, which has key implications for future researchers.
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